File: rfc9132.html

package info (click to toggle)
doc-rfc 20230121-1
links: PTS, VCS
area: non-free
in suites: bookworm, forky, sid, trixie
size: 1,609,944 kB
file content (8004 lines) | stat: -rw-r--r-- 452,237 bytes
<!DOCTYPE html>
<html lang="en" class="RFC">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>RFC 9132: Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Specification</title>
<meta content="Mohamed Boucadair" name="author">
<meta content="Jon Shallow" name="author">
<meta content="Tirumaleswar Reddy.K" name="author">
<meta content="
       This document specifies the Distributed Denial-of-Service Open Threat
      Signaling (DOTS) signal channel, a protocol for signaling the need for
      protection against Distributed Denial-of-Service (DDoS) attacks to a
      server capable of enabling network traffic mitigation on behalf of the
      requesting client. 
       A companion document defines the DOTS data channel, a separate
      reliable communication layer for DOTS management and configuration
      purposes. 
       This document obsoletes RFC 8782. 
    " name="description">
<meta content="xml2rfc 3.9.1" name="generator">
<meta content="security" name="keyword">
<meta content="mitigation" name="keyword">
<meta content="service delivery" name="keyword">
<meta content="connectivity" name="keyword">
<meta content="anti-DDoS" name="keyword">
<meta content="automation" name="keyword">
<meta content="cooperation" name="keyword">
<meta content="resilience" name="keyword">
<meta content="filtering" name="keyword">
<meta content="security center" name="keyword">
<meta content="mitigator" name="keyword">
<meta content="scrubbing" name="keyword">
<meta content="dynamic service protection" name="keyword">
<meta content="dynamic mitigation" name="keyword">
<meta content="cooperative networking" name="keyword">
<meta content="protective networking" name="keyword">
<meta content="9132" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.9.1
    Python 3.6.10
    appdirs 1.4.4
    ConfigArgParse 1.2.3
    google-i18n-address 2.3.5
    html5lib 1.0.1
    intervaltree 3.0.2
    Jinja2 2.11.2
    kitchen 1.2.6
    lxml 4.4.2
    pycairo 1.19.0
    pycountry 19.8.18
    pyflakes 2.1.1
    PyYAML 5.3.1
    requests 2.22.0
    setuptools 40.6.2
    six 1.14.0
    WeasyPrint 51
-->
<link href="rfc9132.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">/*

  NOTE: Changes at the bottom of this file overrides some earlier settings.

  Once the style has stabilized and has been adopted as an official RFC style,
  this can be consolidated so that style settings occur only in one place, but
  for now the contents of this file consists first of the initial CSS work as
  provided to the RFC Formatter (xml2rfc) work, followed by itemized and
  commented changes found necssary during the development of the v3
  formatters.

*/

/* fonts */
@import url('https://fonts.googleapis.com/css?family=Noto+Sans'); /* Sans-serif */
@import url('https://fonts.googleapis.com/css?family=Noto+Serif'); /* Serif (print) */
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono'); /* Monospace */

@viewport {
  zoom: 1.0;
  width: extend-to-zoom;
}
@-ms-viewport {
  width: extend-to-zoom;
  zoom: 1.0;
}
/* general and mobile first */
html {
}
body {
  max-width: 90%;
  margin: 1.5em auto;
  color: #222;
  background-color: #fff;
  font-size: 14px;
  font-family: 'Noto Sans', Arial, Helvetica, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
  display: none;
}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
  margin: 1em 0 0.5em;
  font-weight: bold;
  line-height: 1.3;
}
#title {
  clear: both;
  border-bottom: 1px solid #ddd;
  margin: 0 0 0.5em 0;
  padding: 1em 0 0.5em;
}
.author {
  padding-bottom: 4px;
}
h1 {
  font-size: 26px;
  margin: 1em 0;
}
h2 {
  font-size: 22px;
  margin-top: -20px;  /* provide offset for in-page anchors */
  padding-top: 33px;
}
h3 {
  font-size: 18px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h4 {
  font-size: 16px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h5, h6 {
  font-size: 14px;
}
#n-copyright-notice {
  border-bottom: 1px solid #ddd;
  padding-bottom: 1em;
  margin-bottom: 1em;
}
/* general structure */
p {
  padding: 0;
  margin: 0 0 1em 0;
  text-align: left;
}
div, span {
  position: relative;
}
div {
  margin: 0;
}
.alignRight.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignRight.art-text pre {
  padding: 0;
}
.alignRight {
  margin: 1em 0;
}
.alignRight > *:first-child {
  border: none;
  margin: 0;
  float: right;
  clear: both;
}
.alignRight > *:nth-child(2) {
  clear: both;
  display: block;
  border: none;
}
svg {
  display: block;
}
.alignCenter.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignCenter.art-text pre {
  padding: 0;
}
.alignCenter {
  margin: 1em 0;
}
.alignCenter > *:first-child {
  border: none;
  /* this isn't optimal, but it's an existence proof.  PrinceXML doesn't
     support flexbox yet.
  */
  display: table;
  margin: 0 auto;
}

/* lists */
ol, ul {
  padding: 0;
  margin: 0 0 1em 2em;
}
ol ol, ul ul, ol ul, ul ol {
  margin-left: 1em;
}
li {
  margin: 0 0 0.25em 0;
}
.ulCompact li {
  margin: 0;
}
ul.empty, .ulEmpty {
  list-style-type: none;
}
ul.empty li, .ulEmpty li {
  margin-top: 0.5em;
}
ul.ulBare, li.ulBare {
  margin-left: 0em !important;
}
ul.compact, .ulCompact,
ol.compact, .olCompact {
  line-height: 100%;
  margin: 0 0 0 2em;
}

/* definition lists */
dl {
}
dl > dt {
  float: left;
  margin-right: 1em;
}
/* 
dl.nohang > dt {
  float: none;
}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
  margin-bottom: 0em;
}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0em;
}

/* links */
a {
  text-decoration: none;
}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
}
figcaption a[href],
a[href].selfRef {
  color: #222;
}
/* XXX probably not this:
a.selfRef:hover {
  background-color: transparent;
  cursor: default;
} */

/* Figures */
tt, code, pre, code {
  background-color: #f9f9f9;
  font-family: 'Roboto Mono', monospace;
}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
  max-width: 100%;
}
figure {
  margin: 0;
}
figure blockquote {
  margin: 0.8em 0.4em 0.4em;
}
figcaption {
  font-style: italic;
  margin: 0 0 1em 0;
}
@media screen {
  pre {
    overflow-x: auto;
    max-width: 100%;
    max-width: calc(100% - 22px);
  }
}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 1.2em 2em;
}
blockquote {
  background-color: #f9f9f9;
  color: #111; /* Arlen: WCAG 2019 */
  border: 1px solid #ddd;
  border-radius: 3px;
  margin: 1em 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}

/* tables */
table {
  width: 100%;
  margin: 0 0 1em;
  border-collapse: collapse;
  border: 1px solid #eee;
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.5em 0.75em;
}
th {
  text-align: left;
  background-color: #e9e9e9;
}
tr:nth-child(2n+1) > td {
  background-color: #f5f5f5;
}
table caption {
  font-style: italic;
  margin: 0;
  padding: 0;
  text-align: left;
}
table p {
  /* XXX to avoid bottom margin on table row signifiers. If paragraphs should
     be allowed within tables more generally, it would be far better to select on a class. */
  margin: 0;
}

/* pilcrow */
a.pilcrow {
  color: #666; /* Arlen: AHDJ 2019 */
  text-decoration: none;
  visibility: hidden;
  user-select: none;
  -ms-user-select: none;
  -o-user-select:none;
  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
@media screen {
  aside:hover > a.pilcrow,
  p:hover > a.pilcrow,
  blockquote:hover > a.pilcrow,
  div:hover > a.pilcrow,
  li:hover > a.pilcrow,
  pre:hover > a.pilcrow {
    visibility: visible;
  }
  a.pilcrow:hover {
    background-color: transparent;
  }
}

/* misc */
hr {
  border: 0;
  border-top: 1px solid #eee;
}
.bcp14 {
  font-variant: small-caps;
}

.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
  width: 3em;
  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
#identifiers .authors .author {
  display: inline-block;
  margin-right: 1.5em;
}
#identifiers .authors .org {
  font-style: italic;
}

/* The prepared/rendered info at the very bottom of the page */
.docInfo {
  color: #666; /* Arlen: WCAG 2019 */
  font-size: 0.9em;
  font-style: italic;
  margin-top: 2em;
}
.docInfo .prepared {
  float: left;
}
.docInfo .prepared {
  float: right;
}

/* table of contents */
#toc  {
  padding: 0.75em 0 2em 0;
  margin-bottom: 1em;
}
nav.toc ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
nav.toc li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
/* references */
.references dt {
  text-align: right;
  font-weight: bold;
  min-width: 7em;
}
.references dd {
  margin-left: 8em;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

.references .ascii {
  margin-bottom: 0.25em;
}

/* index */
.index ul {
  margin: 0 0 0 1em;
  padding: 0;
  list-style: none;
}
.index ul ul {
  margin: 0;
}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
  margin: 0.5em 0 1em;
}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
    -moz-column-count: 2;
    -moz-column-gap: 20px;
  }
  .index ul ul {
    -moz-column-count: 1;
    -moz-column-gap: 0;
  }
}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}

address.vcard .nameRole {
  font-weight: 700;
  margin-left: 0;
}
address.vcard .label {
  font-family: "Noto Sans",Arial,Helvetica,sans-serif;
  margin: 0.5em 0;
}
address.vcard .type {
  display: none;
}
.alternative-contact {
  margin: 1.5em 0 1em;
}
hr.addr {
  border-top: 1px dashed;
  margin: 0;
  color: #ddd;
  max-width: calc(100% - 16px);
}

/* temporary notes */
.rfcEditorRemove::before {
  position: absolute;
  top: 0.2em;
  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
  background-color: #ffd; /* Arlen: WCAG 2019 */
}
.rfcEditorRemove {
  position: relative;
  padding-top: 1.8em;
  background-color: #ffd; /* Arlen: WCAG 2019 */
  border-radius: 3px;
}
.cref {
  background-color: #ffd; /* Arlen: WCAG 2019 */
  padding: 2px 4px;
}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 1023px) {
  body {
    padding-top: 2em;
  }
  #title {
    padding: 1em 0;
  }
  h1 {
    font-size: 24px;
  }
  h2 {
    font-size: 20px;
    margin-top: -18px;  /* provide offset for in-page anchors */
    padding-top: 38px;
  }
  #identifiers dd {
    max-width: 60%;
  }
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    background-color: inherit;
    border-bottom: 1px solid #ccc;
  }
  #toc h2 {
    margin: -1px 0 0 0;
    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
    font-size: 1.1em;
    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
    position: relative;
    width: 1em;
    height: 1px;
    left: -164px;
    margin: 6px 0 0 0;
    background: white none repeat scroll 0 0;
    box-shadow: 0 4px 0 0 white, 0 8px 0 0 white;
    content: "";
  }
  #toc nav {
    display: none;
    padding: 0.5em 1em 1em;
    overflow: auto;
    height: calc(100vh - 48px);
    border-left: 1px solid #ddd;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
  body {
    max-width: 724px;
    margin: 42px auto;
    padding-left: 1.5em;
    padding-right: 29em;
  }
  #toc {
    position: fixed;
    top: 42px;
    right: 42px;
    width: 25%;
    margin: 0;
    padding: 0 1em;
    z-index: 1;
  }
  #toc h2 {
    border-top: none;
    border-bottom: 1px solid #ddd;
    font-size: 1em;
    font-weight: normal;
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 0;
    overflow: auto;
  }
  img { /* future proofing */
    max-width: 100%;
    height: auto;
  }
}

/* pagination */
@media print {
  body {

    width: 100%;
  }
  p {
    orphans: 3;
    widows: 3;
  }
  #n-copyright-notice {
    border-bottom: none;
  }
  #toc, #n-introduction {
    page-break-before: always;
  }
  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
    page-break-inside: avoid;
  }
  figure {
    overflow: scroll;
  }
  h1, h2, h3, h4, h5, h6 {
    page-break-after: avoid;
  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
  }
  table {
    border: 1px solid #ddd;
  }
  td {
    border-top: 1px solid #ddd;
  }
}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
  string-set: ears-top-left content();
}

.ears thead .center {
  string-set: ears-top-center content();
}

.ears thead .right {
  string-set: ears-top-right content();
}

.ears tfoot .left {
  string-set: ears-bottom-left content();
}

.ears tfoot .center {
  string-set: ears-bottom-center content();
}

.ears tfoot .right {
  string-set: ears-bottom-right content();
}
*/

@page :first {
  padding-top: 0;
  @top-left {
    content: normal;
    border: none;
  }
  @top-center {
    content: normal;
    border: none;
  }
  @top-right {
    content: normal;
    border: none;
  }
}

@page {
  size: A4;
  margin-bottom: 45mm;
  padding-top: 20px;
  /* The follwing is commented out here, but set appropriately by in code, as
     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-left {
    content: string(ears-top-left);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-center {
    content: string(ears-top-center);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-right {
    content: string(ears-top-right);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @bottom-left {
    content: string(ears-bottom-left);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-center {
    content: string(ears-bottom-center);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-right {
      content: '[Page ' counter(page) ']';
      vertical-align: top;
      border-top: solid 1px #ccc;
  }
  */

}

/* Changes introduced to fix issues found during implementation */
/* Make sure links are clickable even if overlapped by following H* */
a {
  z-index: 2;
}
/* Separate body from document info even without intervening H1 */
section {
  clear: both;
}


/* Top align author divs, to avoid names without organization dropping level with org names */
.author {
  vertical-align: top;
}

/* Leave room in document info to show Internet-Draft on one line */
#identifiers dt {
  width: 8em;
}

/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
  margin-left: 1em;
}

/* Give floating toc a background color (needed when it's a div inside section */
#toc {
  background-color: white;
}

/* Make the collapsed ToC header render white on gray also when it's a link */
@media screen and (max-width: 1023px) {
  #toc h2 a,
  #toc h2 a:link,
  #toc h2 a:focus,
  #toc h2 a:hover,
  #toc a.toplink,
  #toc a.toplink:hover {
    color: white;
    background-color: #444;
    text-decoration: none;
  }
}

/* Give the bottom of the ToC some whitespace */
@media screen and (min-width: 1024px) {
  #toc {
    padding: 0 0 1em 1em;
  }
}

/* Style section numbers with more space between number and title */
.section-number {
  padding-right: 0.5em;
}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
  font-size: 95%;
}

/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
.art-text pre {
  line-height: 1.12;
}


/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin-right: 0.5em;
}

/* Fix the dl styling to match the RFC 7992 attributes */
dl > dt,
dl.dlParallel > dt {
  float: left;
  margin-right: 1em;
}
dl.dlNewline > dt {
  float: none;
}

/* Provide styling for table cell text alignment */
table td.text-left,
table th.text-left {
  text-align: left;
}
table td.text-center,
table th.text-center {
  text-align: center;
}
table td.text-right,
table th.text-right {
  text-align: right;
}

/* Make the alternative author contact informatio look less like just another
   author, and group it closer with the primary author contact information */
.alternative-contact {
  margin: 0.5em 0 0.25em 0;
}
address .non-ascii {
  margin: 0 0 0 2em;
}

/* With it being possible to set tables with alignment
  left, center, and right, { width: 100%; } does not make sense */
table {
  width: auto;
}

/* Avoid reference text that sits in a block with very wide left margin,
   because of a long floating dt label.*/
.references dd {
  overflow: visible;
}

/* Control caption placement */
caption {
  caption-side: bottom;
}

/* Limit the width of the author address vcard, so names in right-to-left
   script don't end up on the other side of the page. */

address.vcard {
  max-width: 30em;
  margin-right: auto;
}

/* For address alignment dependent on LTR or RTL scripts */
address div.left {
  text-align: left;
}
address div.right {
  text-align: right;
}

/* Provide table alignment support.  We can't use the alignX classes above
   since they do unwanted things with caption and other styling. */
table.right {
 margin-left: auto;
 margin-right: 0;
}
table.center {
 margin-left: auto;
 margin-right: auto;
}
table.left {
 margin-left: 0;
 margin-right: auto;
}

/* Give the table caption label the same styling as the figcaption */
caption a[href] {
  color: #222;
}

@media print {
  .toplink {
    display: none;
  }

  /* avoid overwriting the top border line with the ToC header */
  #toc {
    padding-top: 1px;
  }

  /* Avoid page breaks inside dl and author address entries */
  .vcard {
    page-break-inside: avoid;
  }

}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* Make pilcrows on dd visible */
@media screen {
  dd:hover > a.pilcrow {
    visibility: visible;
  }
}
/* Make the placement of figcaption match that of a table's caption
   by removing the figure's added bottom margin */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
   margin-bottom: 0;
}
.alignLeft,
.alignCenter,
.alignRight {
  margin: 1em 0 0 0;
}
/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
   possibly even requiring a new line */
@media print {
  a.pilcrow {
    display: none;
  }
}
/* Styling for the external metadata */
div#external-metadata {
  background-color: #eee;
  padding: 0.5em;
  margin-bottom: 0.5em;
  display: none;
}
div#internal-metadata {
  padding: 0.5em;                       /* to match the external-metadata padding */
}
/* Styling for title RFC Number */
h1#rfcnum {
  clear: both;
  margin: 0 0 -1em;
  padding: 1em 0 0 0;
}
/* Make .olPercent look the same as <ol><li> */
dl.olPercent > dd {
  margin-bottom: 0.25em;
  min-height: initial;
}
/* Give aside some styling to set it apart */
aside {
  border-left: 1px solid #ddd;
  margin: 1em 0 1em 2em;
  padding: 0.2em 2em;
}
aside > dl,
aside > ol,
aside > ul,
aside > table,
aside > p {
  margin-bottom: 0.5em;
}
/* Additional page break settings */
@media print {
  figcaption, table caption {
    page-break-before: avoid;
  }
}
/* Font size adjustments for print */
@media print {
  body  { font-size: 10pt;      line-height: normal; max-width: 96%; }
  h1    { font-size: 1.72em;    padding-top: 1.5em; } /* 1*1.2*1.2*1.2 */
  h2    { font-size: 1.44em;    padding-top: 1.5em; } /* 1*1.2*1.2 */
  h3    { font-size: 1.2em;     padding-top: 1.5em; } /* 1*1.2 */
  h4    { font-size: 1em;       padding-top: 1.5em; }
  h5, h6 { font-size: 1em;      margin: initial; padding: 0.5em 0 0.3em; }
}
/* Sourcecode margin in print, when there's no pilcrow */
@media print {
  .artwork,
  .sourcecode {
    margin-bottom: 1em;
  }
}
/* Avoid narrow tables forcing too narrow table captions, which may render badly */
table {
  min-width: 20em;
}
/* ol type a */
ol.type-a { list-style-type: lower-alpha; }
ol.type-A { list-style-type: upper-alpha; }
ol.type-i { list-style-type: lower-roman; }
ol.type-I { list-style-type: lower-roman; }
/* Apply the print table and row borders in general, on request from the RPC,
and increase the contrast between border and odd row background sligthtly */
table {
  border: 1px solid #ddd;
}
td {
  border-top: 1px solid #ddd;
}
tr:nth-child(2n+1) > td {
  background-color: #f8f8f8;
}
/* Use style rules to govern display of the TOC. */
@media screen and (max-width: 1023px) {
  #toc nav { display: none; }
  #toc.active nav { display: block; }
}
/* Add support for keepWithNext */
.keepWithNext {
  break-after: avoid-page;
  break-after: avoid-page;
}
/* Add support for keepWithPrevious */
.keepWithPrevious {
  break-before: avoid-page;
}
/* Change the approach to avoiding breaks inside artwork etc. */
figure, pre, table, .artwork, .sourcecode  {
  break-before: avoid-page;
  break-after: auto;
}
/* Avoid breaks between <dt> and <dd> */
dl {
  break-before: auto;
  break-inside: auto;
}
dt {
  break-before: auto;
  break-after: avoid-page;
}
dd {
  break-before: avoid-page;
  break-after: auto;
  orphans: 3;
  widows: 3
}
span.break, dd.break {
  margin-bottom: 0;
  min-height: 0;
  break-before: auto;
  break-inside: auto;
  break-after: auto;
}
/* Undo break-before ToC */
@media print {
  #toc {
    break-before: auto;
  }
}
/* Text in compact lists should not get extra bottim margin space,
   since that would makes the list not compact */
ul.compact p, .ulCompact p,
ol.compact p, .olCompact p {
 margin: 0;
}
/* But the list as a whole needs the extra space at the end */
section ul.compact,
section .ulCompact,
section ol.compact,
section .olCompact {
  margin-bottom: 1em;                    /* same as p not within ul.compact etc. */
}
/* The tt and code background above interferes with for instance table cell
   backgrounds.  Changed to something a bit more selective. */
tt, code {
  background-color: transparent;
}
p tt, p code, li tt, li code {
  background-color: #f8f8f8;
}
/* Tweak the pre margin -- 0px doesn't come out well */
pre {
   margin-top: 0.5px;
}
/* Tweak the comact list text */
ul.compact, .ulCompact,
ol.compact, .olCompact,
dl.compact, .dlCompact {
  line-height: normal;
}
/* Don't add top margin for nested lists */
li > ul, li > ol, li > dl,
dd > ul, dd > ol, dd > dl,
dl > dd > dl {
  margin-top: initial;
}
/* Elements that should not be rendered on the same line as a <dt> */
/* This should match the element list in writer.text.TextWriter.render_dl() */
dd > div.artwork:first-child,
dd > aside:first-child,
dd > figure:first-child,
dd > ol:first-child,
dd > div:first-child > pre.sourcecode,
dd > table:first-child,
dd > ul:first-child {
  clear: left;
}
/* fix for weird browser behaviour when <dd/> is empty */
dt+dd:empty::before{
  content: "\00a0";
}
/* Make paragraph spacing inside <li> smaller than in body text, to fit better within the list */
li > p {
  margin-bottom: 0.5em
}
/* Don't let p margin spill out from inside list items */
li > p:last-of-type {
  margin-bottom: 0;
}
</style>
<link href="rfc-local.css" rel="stylesheet" type="text/css">
<link href="https://dx.doi.org/10.17487/rfc9132" rel="alternate">
  <link href="urn:issn:2070-1721" rel="alternate">
  <link href="https://datatracker.ietf.org/doc/draft-ietf-dots-rfc8782-bis-08" rel="prev">
  </head>
<body>
<script src="https://www.rfc-editor.org/js/metadata.min.js"></script>
<table class="ears">
<thead><tr>
<td class="left">RFC 9132</td>
<td class="center">DOTS Signal Channel Protocol</td>
<td class="right">September 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Boucadair, et al.</td>
<td class="center">Standards Track</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-stream">Stream:</dt>
<dd class="stream">Internet Engineering Task Force (IETF)</dd>
<dt class="label-rfc">RFC:</dt>
<dd class="rfc"><a href="https://www.rfc-editor.org/rfc/rfc9132" class="eref">9132</a></dd>
<dt class="label-obsoletes">Obsoletes:</dt>
<dd class="obsoletes">
<a href="https://www.rfc-editor.org/rfc/rfc8782" class="eref">8782</a> </dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2021-09" class="published">September 2021</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">M. Boucadair, <span class="editor">Ed.</span>
</div>
<div class="org">Orange</div>
</div>
<div class="author">
      <div class="author-name">J. Shallow</div>
</div>
<div class="author">
      <div class="author-name">T. Reddy.K</div>
<div class="org">Akamai</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9132</h1>
<h1 id="title">Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Specification</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document specifies the Distributed Denial-of-Service Open Threat
      Signaling (DOTS) signal channel, a protocol for signaling the need for
      protection against Distributed Denial-of-Service (DDoS) attacks to a
      server capable of enabling network traffic mitigation on behalf of the
      requesting client.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
<p id="section-abstract-2">A companion document defines the DOTS data channel, a separate
      reliable communication layer for DOTS management and configuration
      purposes.<a href="#section-abstract-2" class="pilcrow">¶</a></p>
<p id="section-abstract-3">This document obsoletes RFC 8782.<a href="#section-abstract-3" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This is an Internet Standards Track document.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            <span><a href="https://www.rfc-editor.org/info/rfc9132">https://www.rfc-editor.org/info/rfc9132</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2021 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Simplified BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Simplified BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1" class="keepWithNext"><a href="#section-2" class="xref">2</a>.  <a href="#name-terminology" class="xref">Terminology</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.3">
            <p id="section-toc.1-1.3.1"><a href="#section-3" class="xref">3</a>.  <a href="#name-design-overview" class="xref">Design Overview</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.3.2.1">
                <p id="section-toc.1-1.3.2.1.1" class="keepWithNext"><a href="#section-3.1" class="xref">3.1</a>.  <a href="#name-backward-compatibility-cons" class="xref">Backward Compatibility Considerations</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4">
            <p id="section-toc.1-1.4.1"><a href="#section-4" class="xref">4</a>.  <a href="#name-dots-signal-channel-message" class="xref">DOTS Signal Channel: Messages &amp; Behaviors</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.1">
                <p id="section-toc.1-1.4.2.1.1"><a href="#section-4.1" class="xref">4.1</a>.  <a href="#name-dots-servers-discovery" class="xref">DOTS Server(s) Discovery</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.2">
                <p id="section-toc.1-1.4.2.2.1"><a href="#section-4.2" class="xref">4.2</a>.  <a href="#name-coap-uris" class="xref">CoAP URIs</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.3">
                <p id="section-toc.1-1.4.2.3.1"><a href="#section-4.3" class="xref">4.3</a>.  <a href="#name-happy-eyeballs-for-dots-sig" class="xref">Happy Eyeballs for DOTS Signal Channel</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4">
                <p id="section-toc.1-1.4.2.4.1"><a href="#section-4.4" class="xref">4.4</a>.  <a href="#name-dots-mitigation-methods" class="xref">DOTS Mitigation Methods</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.1">
                    <p id="section-toc.1-1.4.2.4.2.1.1"><a href="#section-4.4.1" class="xref">4.4.1</a>.  <a href="#name-request-mitigation" class="xref">Request Mitigation</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.1.2.1">
                        <p id="section-toc.1-1.4.2.4.2.1.2.1.1"><a href="#section-4.4.1.1" class="xref">4.4.1.1</a>.  <a href="#name-building-mitigation-request" class="xref">Building Mitigation Requests</a></p>
</li>
                      <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.1.2.2">
                        <p id="section-toc.1-1.4.2.4.2.1.2.2.1"><a href="#section-4.4.1.2" class="xref">4.4.1.2</a>.  <a href="#name-server-domain-dots-gateways" class="xref">Server-Domain DOTS Gateways</a></p>
</li>
                      <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.1.2.3">
                        <p id="section-toc.1-1.4.2.4.2.1.2.3.1"><a href="#section-4.4.1.3" class="xref">4.4.1.3</a>.  <a href="#name-processing-mitigation-reque" class="xref">Processing Mitigation Requests</a></p>
</li>
                    </ul>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.2">
                    <p id="section-toc.1-1.4.2.4.2.2.1"><a href="#section-4.4.2" class="xref">4.4.2</a>.  <a href="#name-retrieve-information-relate" class="xref">Retrieve Information Related to a Mitigation</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.2.2.1">
                        <p id="section-toc.1-1.4.2.4.2.2.2.1.1"><a href="#section-4.4.2.1" class="xref">4.4.2.1</a>.  <a href="#name-dots-servers-sending-mitiga" class="xref">DOTS Servers Sending Mitigation Status</a></p>
</li>
                      <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.2.2.2">
                        <p id="section-toc.1-1.4.2.4.2.2.2.2.1"><a href="#section-4.4.2.2" class="xref">4.4.2.2</a>.  <a href="#name-dots-clients-polling-for-mi" class="xref">DOTS Clients Polling for Mitigation Status</a></p>
</li>
                    </ul>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.3">
                    <p id="section-toc.1-1.4.2.4.2.3.1"><a href="#section-4.4.3" class="xref">4.4.3</a>.  <a href="#name-efficacy-update-from-dots-c" class="xref">Efficacy Update from DOTS Clients</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.4.2.4">
                    <p id="section-toc.1-1.4.2.4.2.4.1"><a href="#section-4.4.4" class="xref">4.4.4</a>.  <a href="#name-withdraw-a-mitigation" class="xref">Withdraw a Mitigation</a></p>
</li>
                </ul>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.5">
                <p id="section-toc.1-1.4.2.5.1"><a href="#section-4.5" class="xref">4.5</a>.  <a href="#name-dots-signal-channel-session" class="xref">DOTS Signal Channel Session Configuration</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.5.2.1">
                    <p id="section-toc.1-1.4.2.5.2.1.1"><a href="#section-4.5.1" class="xref">4.5.1</a>.  <a href="#name-discover-configuration-para" class="xref">Discover Configuration Parameters</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.5.2.2">
                    <p id="section-toc.1-1.4.2.5.2.2.1"><a href="#section-4.5.2" class="xref">4.5.2</a>.  <a href="#name-convey-dots-signal-channel-" class="xref">Convey DOTS Signal Channel Session Configuration</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.5.2.3">
                    <p id="section-toc.1-1.4.2.5.2.3.1"><a href="#section-4.5.3" class="xref">4.5.3</a>.  <a href="#name-configuration-freshness-and" class="xref">Configuration Freshness and Notifications</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.5.2.4">
                    <p id="section-toc.1-1.4.2.5.2.4.1"><a href="#section-4.5.4" class="xref">4.5.4</a>.  <a href="#name-delete-dots-signal-channel-" class="xref">Delete DOTS Signal Channel Session Configuration</a></p>
</li>
                </ul>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.6">
                <p id="section-toc.1-1.4.2.6.1"><a href="#section-4.6" class="xref">4.6</a>.  <a href="#name-redirected-signaling" class="xref">Redirected Signaling</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.4.2.7">
                <p id="section-toc.1-1.4.2.7.1"><a href="#section-4.7" class="xref">4.7</a>.  <a href="#name-heartbeat-mechanism" class="xref">Heartbeat Mechanism</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.5">
            <p id="section-toc.1-1.5.1"><a href="#section-5" class="xref">5</a>.  <a href="#name-dots-signal-channel-yang-mo" class="xref">DOTS Signal Channel YANG Modules</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.5.2.1">
                <p id="section-toc.1-1.5.2.1.1"><a href="#section-5.1" class="xref">5.1</a>.  <a href="#name-tree-structure" class="xref">Tree Structure</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.5.2.2">
                <p id="section-toc.1-1.5.2.2.1"><a href="#section-5.2" class="xref">5.2</a>.  <a href="#name-iana-dots-signal-channel-ya" class="xref">IANA DOTS Signal Channel YANG Module</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.5.2.3">
                <p id="section-toc.1-1.5.2.3.1"><a href="#section-5.3" class="xref">5.3</a>.  <a href="#name-ietf-dots-signal-channel-ya" class="xref">IETF DOTS Signal Channel YANG Module</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-yang-json-mapping-parameter" class="xref">YANG/JSON Mapping Parameters to CBOR</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#section-7" class="xref">7</a>.  <a href="#name-dtls-protocol-profile-and-p" class="xref">(D)TLS Protocol Profile and Performance Considerations</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.7.2.1">
                <p id="section-toc.1-1.7.2.1.1"><a href="#section-7.1" class="xref">7.1</a>.  <a href="#name-dtls-protocol-profile" class="xref">(D)TLS Protocol Profile</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.7.2.2">
                <p id="section-toc.1-1.7.2.2.1"><a href="#section-7.2" class="xref">7.2</a>.  <a href="#name-dtls-13-considerations" class="xref">(D)TLS 1.3 Considerations</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.7.2.3">
                <p id="section-toc.1-1.7.2.3.1"><a href="#section-7.3" class="xref">7.3</a>.  <a href="#name-dtls-mtu-and-fragmentation" class="xref">DTLS MTU and Fragmentation</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#section-8" class="xref">8</a>.  <a href="#name-mutual-authentication-of-do" class="xref">Mutual Authentication of DOTS Agents &amp; Authorization of DOTS Clients</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#section-9" class="xref">9</a>.  <a href="#name-error-handling" class="xref">Error Handling</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-10" class="xref">10</a>. <a href="#name-iana-considerations" class="xref">IANA Considerations</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.1">
                <p id="section-toc.1-1.10.2.1.1"><a href="#section-10.1" class="xref">10.1</a>.  <a href="#name-dots-signal-channel-udp-and" class="xref">DOTS Signal Channel UDP and TCP Port Number</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.2">
                <p id="section-toc.1-1.10.2.2.1"><a href="#section-10.2" class="xref">10.2</a>.  <a href="#name-well-known-dots-uri" class="xref">Well-Known 'dots' URI</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.3">
                <p id="section-toc.1-1.10.2.3.1"><a href="#section-10.3" class="xref">10.3</a>.  <a href="#name-media-type-registration" class="xref">Media Type Registration</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.4">
                <p id="section-toc.1-1.10.2.4.1"><a href="#section-10.4" class="xref">10.4</a>.  <a href="#name-coap-content-formats-regist" class="xref">CoAP Content-Formats Registration</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.5">
                <p id="section-toc.1-1.10.2.5.1"><a href="#section-10.5" class="xref">10.5</a>.  <a href="#name-cbor-tag-registration" class="xref">CBOR Tag Registration</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6">
                <p id="section-toc.1-1.10.2.6.1"><a href="#section-10.6" class="xref">10.6</a>.  <a href="#name-dots-signal-channel-protoco" class="xref">DOTS Signal Channel Protocol Registry</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.1">
                    <p id="section-toc.1-1.10.2.6.2.1.1"><a href="#section-10.6.1" class="xref">10.6.1</a>.  <a href="#name-dots-signal-channel-cbor-ke" class="xref">DOTS Signal Channel CBOR Key Values Subregistry</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.1.2.1">
                        <p id="section-toc.1-1.10.2.6.2.1.2.1.1"><a href="#section-10.6.1.1" class="xref">10.6.1.1</a>.  <a href="#name-registration-template" class="xref">Registration Template</a></p>
</li>
                      <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.1.2.2">
                        <p id="section-toc.1-1.10.2.6.2.1.2.2.1"><a href="#section-10.6.1.2" class="xref">10.6.1.2</a>.  <a href="#name-update-subregistry-content" class="xref">Update Subregistry Content</a></p>
</li>
                    </ul>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.2">
                    <p id="section-toc.1-1.10.2.6.2.2.1"><a href="#section-10.6.2" class="xref">10.6.2</a>.  <a href="#name-status-codes-subregistry" class="xref">Status Codes Subregistry</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.3">
                    <p id="section-toc.1-1.10.2.6.2.3.1"><a href="#section-10.6.3" class="xref">10.6.3</a>.  <a href="#name-conflict-status-codes-subre" class="xref">Conflict Status Codes Subregistry</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.4">
                    <p id="section-toc.1-1.10.2.6.2.4.1"><a href="#section-10.6.4" class="xref">10.6.4</a>.  <a href="#name-conflict-cause-codes-subreg" class="xref">Conflict Cause Codes Subregistry</a></p>
</li>
                  <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.6.2.5">
                    <p id="section-toc.1-1.10.2.6.2.5.1"><a href="#section-10.6.5" class="xref">10.6.5</a>.  <a href="#name-attack-status-codes-subregi" class="xref">Attack Status Codes Subregistry</a></p>
</li>
                </ul>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.10.2.7">
                <p id="section-toc.1-1.10.2.7.1"><a href="#section-10.7" class="xref">10.7</a>.  <a href="#name-dots-signal-channel-yang-mod" class="xref">DOTS Signal Channel YANG Modules</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#section-11" class="xref">11</a>. <a href="#name-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.12">
            <p id="section-toc.1-1.12.1"><a href="#section-12" class="xref">12</a>. <a href="#name-references" class="xref">References</a></p>
<ul class="toc ulEmpty ulBare compact">
<li class="toc ulEmpty ulBare compact" id="section-toc.1-1.12.2.1">
                <p id="section-toc.1-1.12.2.1.1"><a href="#section-12.1" class="xref">12.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.12.2.2">
                <p id="section-toc.1-1.12.2.2.1"><a href="#section-12.2" class="xref">12.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.13">
            <p id="section-toc.1-1.13.1"><a href="#appendix-A" class="xref">Appendix A</a>.  <a href="#name-summary-of-changes-from-rfc" class="xref">Summary of Changes From RFC 8782</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.14">
            <p id="section-toc.1-1.14.1"><a href="#appendix-B" class="xref">Appendix B</a>.  <a href="#name-cuid-generation" class="xref">CUID Generation</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.15">
            <p id="section-toc.1-1.15.1"><a href="#appendix-C" class="xref">Appendix C</a>.  <a href="#name-summary-of-protocol-recomme" class="xref">Summary of Protocol Recommended/Default Values</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.16">
            <p id="section-toc.1-1.16.1"><a href="#appendix-D" class="xref"></a><a href="#name-acknowledgements" class="xref">Acknowledgements</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.17">
            <p id="section-toc.1-1.17.1"><a href="#appendix-E" class="xref"></a><a href="#name-contributors" class="xref">Contributors</a></p>
</li>
          <li class="toc ulEmpty ulBare compact" id="section-toc.1-1.18">
            <p id="section-toc.1-1.18.1"><a href="#appendix-F" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="introduction">
<section id="section-1">
      <h2 id="name-introduction">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
      </h2>
<p id="section-1-1">A Distributed Denial-of-Service (DDoS) attack is a distributed
      attempt to make machines or network resources unavailable to their
      intended users. In most cases, sufficient scale for an effective attack
      can be achieved by compromising enough end hosts and using those
      infected hosts to perpetrate and amplify the attack. The victim in this
      attack can be an application server, a host, a router, a firewall, or an
      entire network.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">Network applications have finite resources, like CPU cycles, the
      number of processes or threads they can create and use, the maximum
      number of simultaneous connections they can handle, the resources
      assigned to the control plane, etc. When processing network traffic,
      such applications are supposed to use these resources to provide the
      intended functionality in the most efficient manner. However, a DDoS
      attacker may be able to prevent an application from performing its
      intended task by making the application exhaust its finite
      resources.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">A TCP DDoS SYN flood <span>[<a href="#RFC4987" class="xref">RFC4987</a>]</span>, for example, is
      a memory-exhausting attack, while an ACK flood is a CPU-exhausting
      attack. Attacks on the link are carried out by sending enough traffic so
      that the link becomes congested, thereby likely causing packet loss for
      legitimate traffic. Stateful firewalls can also be attacked by sending
      traffic that causes the firewall to maintain an excessive number of
      states that may jeopardize the firewall's operation overall, in addition
      to likely performance impacts. The firewall then runs out of memory, and
      it can no longer instantiate the states required to process legitimate
      flows. Other possible DDoS attacks are discussed in <span>[<a href="#RFC4732" class="xref">RFC4732</a>]</span>.<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">In many cases, it may not be possible for network administrators to
      determine the cause(s) of an attack. They may instead just realize that
      certain resources seem to be under attack. This document defines a
      lightweight protocol that allows a DOTS client to request mitigation
      from one or more DOTS servers for protection against detected,
      suspected, or anticipated attacks. This protocol enables cooperation
      between DOTS agents to permit a highly automated network defense that is
      robust, reliable, and secure. Note that "secure" means the support of
      the features defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8612#section-2.4" class="relref">Section 2.4</a> of [<a href="#RFC8612" class="xref">RFC8612</a>]</span>.<a href="#section-1-4" class="pilcrow">¶</a></p>
<p id="section-1-5">In typical deployments, the DOTS client belongs to a different
      administrative domain than the DOTS server. For example, the DOTS client
      is embedded in a firewall-protected service owned and operated by a
      customer, while the DOTS server is owned and operated by a different
      administrative entity (service provider, typically) providing DDoS
      mitigation services. The latter might or might not provide connectivity
      services to the network hosting the DOTS client.<a href="#section-1-5" class="pilcrow">¶</a></p>
<p id="section-1-6">The DOTS server may or may not be co-located with the DOTS mitigator.
      In typical deployments, the DOTS server belongs to the same
      administrative domain as the mitigator. The DOTS client can communicate
      directly with a DOTS server or indirectly via a DOTS gateway.<a href="#section-1-6" class="pilcrow">¶</a></p>
<p id="section-1-7">An example of a network diagram that illustrates a deployment of DOTS
      agents is shown in <a href="#fig1" class="xref">Figure 1</a>. In this example, a DOTS
      server is operating on the access network. A DOTS client is located on
      the Local Area Network (LAN), while a DOTS gateway is embedded in the
      Customer Premises Equipment (CPE).<a href="#section-1-7" class="pilcrow">¶</a></p>
<span id="name-sample-dots-deployment-1"></span><div id="fig1">
<figure id="figure-1">
        <div class="artwork art-text alignLeft" id="section-1-8.1">
<pre>
   Network
   Resource          CPE Router      Access Network      __________
+-------------+   +--------------+   +-------------+    /          \
|             |   |              |   |             |    | Internet |
| DOTS Client +---+ DOTS Gateway +---+ DOTS Server +----+          |
|             |   |              |   |             |    |          |
+-------------+   +--------------+   +-------------+    \__________/
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-sample-dots-deployment-1" class="selfRef">Sample DOTS Deployment (1)</a>
        </figcaption></figure>
</div>
<p id="section-1-9">DOTS servers can also be reachable over the Internet, as depicted in
      <a href="#fig_blah" class="xref">Figure 2</a>.<a href="#section-1-9" class="pilcrow">¶</a></p>
<span id="name-sample-dots-deployment-2"></span><div id="fig_blah">
<figure id="figure-2">
        <div class="artwork art-text alignCenter" id="section-1-10.1">
<pre>
   Network                                          DDoS Mitigation
   Resource          CPE Router        _________        Service
+-------------+   +--------------+    /         \   +-------------+
|             |   |              |   |          |   |             |
| DOTS Client +---+ DOTS Gateway +---+ Internet +---+ DOTS Server |
|             |   |              |   |          |   |             |
+-------------+   +--------------+    \_________/   +-------------+
</pre>
</div>
<figcaption><a href="#figure-2" class="selfRef">Figure 2</a>:
<a href="#name-sample-dots-deployment-2" class="selfRef">Sample DOTS Deployment (2)</a>
        </figcaption></figure>
</div>
<p id="section-1-11">This document adheres to the DOTS architecture <span>[<a href="#RFC8811" class="xref">RFC8811</a>]</span>. The requirements for the DOTS signal channel
      protocol are documented in <span>[<a href="#RFC8612" class="xref">RFC8612</a>]</span>. This document
      satisfies all the use cases discussed in <span>[<a href="#RFC8903" class="xref">RFC8903</a>]</span>.<a href="#section-1-11" class="pilcrow">¶</a></p>
<p id="section-1-12">This document focuses on the DOTS signal channel. This is a companion
      document of the DOTS data channel specification <span>[<a href="#RFC8783" class="xref">RFC8783</a>]</span> that defines a configuration and a bulk data
      exchange mechanism supporting the DOTS signal channel.<a href="#section-1-12" class="pilcrow">¶</a></p>
<p id="section-1-13">Backward compatibility (including upgrade) considerations are
      discussed in <a href="#back" class="xref">Section 3.1</a>.<a href="#section-1-13" class="pilcrow">¶</a></p>
</section>
</div>
<div id="notation">
<section id="section-2">
      <h2 id="name-terminology">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-terminology" class="section-name selfRef">Terminology</a>
      </h2>
<p id="section-2-1">
    The key words "<span class="bcp14">MUST</span>", "<span class="bcp14">MUST NOT</span>", "<span class="bcp14">REQUIRED</span>", "<span class="bcp14">SHALL</span>", "<span class="bcp14">SHALL NOT</span>", "<span class="bcp14">SHOULD</span>", "<span class="bcp14">SHOULD NOT</span>", "<span class="bcp14">RECOMMENDED</span>", "<span class="bcp14">NOT RECOMMENDED</span>",
    "<span class="bcp14">MAY</span>", and "<span class="bcp14">OPTIONAL</span>" in this document are to be interpreted as
    described in BCP 14 <span>[<a href="#RFC2119" class="xref">RFC2119</a>]</span> <span>[<a href="#RFC8174" class="xref">RFC8174</a>]</span> 
    when, and only when, they appear in all capitals, as shown here.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">(D)TLS is used for statements that apply to both Transport Layer
      Security <span>[<a href="#RFC5246" class="xref">RFC5246</a>]</span> <span>[<a href="#RFC8446" class="xref">RFC8446</a>]</span>
      and Datagram Transport Layer Security <span>[<a href="#RFC6347" class="xref">RFC6347</a>]</span>.
      Specific terms are used for any statement that applies to either
      protocol alone.<a href="#section-2-2" class="pilcrow">¶</a></p>
<p id="section-2-3">The reader should be familiar with the terms defined in <span>[<a href="#RFC8612" class="xref">RFC8612</a>]</span> and <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>.<a href="#section-2-3" class="pilcrow">¶</a></p>
<p id="section-2-4">The meaning of the symbols in YANG tree diagrams are defined in <span>[<a href="#RFC8340" class="xref">RFC8340</a>]</span> and <span>[<a href="#RFC8791" class="xref">RFC8791</a>]</span>.<a href="#section-2-4" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-3">
      <h2 id="name-design-overview">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-design-overview" class="section-name selfRef">Design Overview</a>
      </h2>
<p id="section-3-1">The DOTS signal channel is built on top of the Constrained
      Application Protocol (CoAP) <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>, a
      lightweight protocol originally designed for constrained devices and
      networks. The many features of CoAP (expectation of packet loss, support
      for asynchronous Non-confirmable messaging, congestion control, small
      message overhead limiting the need for fragmentation, use of minimal
      resources, and support for (D)TLS) make it a good candidate upon which
      to build the DOTS signaling mechanism.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">DOTS clients and servers behave as CoAP endpoints. By default, a DOTS
      client behaves as a CoAP client and a DOTS server behaves as CoAP
      server. Nevertheless, a DOTS client (or server) behaves as a CoAP server
      (or client) for specific operations, such as DOTS heartbeat operations
      (<a href="#hb" class="xref">Section 4.7</a>).<a href="#section-3-2" class="pilcrow">¶</a></p>
<p id="section-3-3">The DOTS signal channel is layered on existing standards (see <a href="#fig_dots" class="xref">Figure 3</a>).<a href="#section-3-3" class="pilcrow">¶</a></p>
<span id="name-abstract-layering-of-dots-s"></span><div id="fig_dots">
<figure id="figure-3">
        <div class="artwork art-text alignCenter" id="section-3-4.1">
<pre>
+---------------------+
| DOTS Signal Channel |
+---------------------+
|         CoAP        |
+----------+----------+
|   TLS    |   DTLS   |
+----------+----------+
|   TCP    |   UDP    |
+----------+----------+
|          IP         |
+---------------------+
</pre>
</div>
<figcaption><a href="#figure-3" class="selfRef">Figure 3</a>:
<a href="#name-abstract-layering-of-dots-s" class="selfRef">Abstract Layering of DOTS Signal Channel over CoAP over (D)TLS</a>
        </figcaption></figure>
</div>
<p id="section-3-5">In some cases, a DOTS client and server may have a mutual agreement
      to use a specific port number, such as by explicit configuration or
      dynamic discovery <span>[<a href="#RFC8973" class="xref">RFC8973</a>]</span>. Absent such mutual
      agreement, the DOTS signal channel <span class="bcp14">MUST</span> run over 
      port number 4646, as
      defined in <a href="#port" class="xref">Section 10.1</a>, for both UDP and TCP (that is,
      the DOTS server listens on port number 4646). In order to use a distinct
      port number (as opposed to 4646), DOTS clients and servers <span class="bcp14">SHOULD</span>
      support a configurable parameter to supply the port number to
      use.<a href="#section-3-5" class="pilcrow">¶</a></p>
<aside id="section-3-6">
        <p id="section-3-6.1">Note: The rationale for not using the default port number 5684
        ((D)TLS CoAP) is to avoid the discovery of services and
        resources discussed in <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span> 
 and allow for differentiated
        behaviors in environments where both a DOTS gateway and an
        Internet of Things (IoT) gateway (e.g., Figure 3 of <span>[<a href="#RFC7452" class="xref">RFC7452</a>]</span>) are co-located.<a href="#section-3-6.1" class="pilcrow">¶</a></p>
<p id="section-3-6.2">Particularly, the use of a default port number is meant to
        simplify DOTS deployment in scenarios where no explicit IP
        address configuration is required.  For example, the use of the
        default router as the DOTS server aims to ease DOTS deployment
        within LANs (in which CPEs embed a DOTS gateway, as illustrated
        in Figures 1 and 2) without requiring a sophisticated discovery
        method and configuration tasks within the LAN.  It is also
        possible to use anycast addresses for DOTS servers to simplify
        DOTS client configuration, including service discovery.  In
        such an anycast-based scenario, a DOTS client initiating a DOTS
        session to the DOTS server anycast address may, for example, be
        (1) redirected to the DOTS server unicast address to be used by
        the DOTS client following the procedure discussed in
        <a href="#redirect" class="xref">Section 4.6</a> or (2) relayed to a unicast DOTS server.<a href="#section-3-6.2" class="pilcrow">¶</a></p>
</aside>
<p id="section-3-7">The signal channel uses the "coaps" URI scheme defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-6" class="relref">Section 6</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span> and the "coaps+tcp" URI scheme defined
      in <span><a href="https://www.rfc-editor.org/rfc/rfc8323#section-8.2" class="relref">Section 8.2</a> of [<a href="#RFC8323" class="xref">RFC8323</a>]</span> to identify DOTS server
      resources that are accessible using CoAP over UDP secured with DTLS and
      CoAP over TCP secured with TLS, respectively.<a href="#section-3-7" class="pilcrow">¶</a></p>
<p id="section-3-8">The DOTS signal channel can be established between two DOTS agents
      prior to or during an attack. The DOTS signal channel is initiated by
      the DOTS client. The DOTS client can then negotiate, configure, and
      retrieve the DOTS signal channel session behavior with its DOTS peer
      (<a href="#sigconfig" class="xref">Section 4.5</a>). Once the signal channel is
      established, the DOTS agents may periodically send heartbeats to keep
      the channel active (<a href="#hb" class="xref">Section 4.7</a>). At any time, the DOTS
      client may send a mitigation request message (<a href="#m_req" class="xref">Section 4.4</a>) to a DOTS server over the active signal channel.
      While mitigation is active (because of the higher likelihood of packet
      loss during a DDoS attack), the DOTS server periodically sends status
      messages to the client, including basic mitigation feedback details.
      Mitigation remains active until the DOTS client explicitly terminates
      mitigation or the mitigation lifetime expires. Also, the DOTS server may
      rely on the signal channel session loss to trigger mitigation for
      preconfigured mitigation requests (if any).<a href="#section-3-8" class="pilcrow">¶</a></p>
<p id="section-3-9">DOTS signaling can use DTLS over UDP and TLS over TCP. Likewise, DOTS
      requests may be sent using IPv4 or IPv6 transfer capabilities. A Happy
      Eyeballs procedure for the DOTS signal channel is specified in <a href="#HE" class="xref">Section 4.3</a>.<a href="#section-3-9" class="pilcrow">¶</a></p>
<p id="section-3-10">A DOTS client is entitled to access only the resources it creates. In
      particular, a DOTS client cannot retrieve data related to mitigation
      requests created by other DOTS clients of the same DOTS client
      domain.<a href="#section-3-10" class="pilcrow">¶</a></p>
<p id="section-3-11">Messages exchanged between DOTS agents are serialized using Concise
      Binary Object Representation (CBOR) <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>, a
      binary encoding scheme designed for small code and message size.
      CBOR-encoded payloads are used to carry signal-channel-specific payload
      messages that convey request parameters and response information, such as
      errors. In order to allow the reusing of data models across protocols,
      <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span> specifies the JavaScript Object Notation
      (JSON) encoding of YANG-modeled data. A similar effort for CBOR is
      defined in <span>[<a href="#I-D.ietf-core-yang-cbor" class="xref">CORE-YANG-CBOR</a>]</span>.<a href="#section-3-11" class="pilcrow">¶</a></p>
<p id="section-3-12">DOTS agents determine that a CBOR data structure is a DOTS signal
      channel object from the application context, such as from the port
      number assigned to the DOTS signal channel. The other method DOTS agents
      use to indicate that a CBOR data structure is a DOTS signal channel
      object is the use of the "application/dots+cbor" content type (<a href="#MediaReg" class="xref">Section 10.3</a>).<a href="#section-3-12" class="pilcrow">¶</a></p>
<p id="section-3-13">This document specifies a YANG module for representing DOTS
      mitigation scopes, DOTS signal channel session configuration data, and
      DOTS redirected signaling (<a href="#YANG" class="xref">Section 5</a>). All parameters
      in the payload of the DOTS signal channel are mapped to CBOR types, as
      specified in <a href="#table5" class="xref">Table 5</a> (<a href="#mapping" class="xref">Section 6</a>).<a href="#section-3-13" class="pilcrow">¶</a></p>
<p id="section-3-14">In order to prevent fragmentation, DOTS agents must follow the
      recommendations documented in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.6" class="relref">Section 4.6</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>.
      Refer to <a href="#mtu" class="xref">Section 7.3</a> for more
      details.<a href="#section-3-14" class="pilcrow">¶</a></p>
<p id="section-3-15">DOTS agents <span class="bcp14">MUST</span> support GET, PUT, and DELETE CoAP methods. The
      payload included in CoAP responses with 2.xx Response Codes <span class="bcp14">MUST</span> be of
      content type "application/dots+cbor". CoAP responses with 4.xx and 5.xx
      error Response Codes <span class="bcp14">MUST</span> include a diagnostic payload
      (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.5.2" class="relref">Section 5.5.2</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>). The diagnostic 
      payload may contain
      additional information to aid troubleshooting.<a href="#section-3-15" class="pilcrow">¶</a></p>
<p id="section-3-16">In deployments where multiple DOTS clients are enabled in a single
      network and administrative domain (called DOTS client domain), the DOTS
      server may detect conflicting mitigation requests from these clients.
      This document does not aim to specify a comprehensive list of conditions
      under which a DOTS server will characterize two mitigation requests from
      distinct DOTS clients as conflicting, nor does it recommend a DOTS
      server behavior for processing conflicting mitigation requests. Those
      considerations are implementation and deployment specific. Nevertheless,
      this document specifies the mechanisms to notify DOTS clients when
      conflicts occur, including the conflict cause (<a href="#pro-mit-req" class="xref">Section 4.4.1.3</a>).<a href="#section-3-16" class="pilcrow">¶</a></p>
<p id="section-3-17">In deployments where one or more translators (e.g., Traditional NAT
      <span>[<a href="#RFC3022" class="xref">RFC3022</a>]</span>, CGN <span>[<a href="#RFC6888" class="xref">RFC6888</a>]</span>,
      NAT64 <span>[<a href="#RFC6146" class="xref">RFC6146</a>]</span>, NPTv6 <span>[<a href="#RFC6296" class="xref">RFC6296</a>]</span>) are
      enabled between the client's network and
      the DOTS server, any DOTS signal channel messages forwarded to a DOTS
      server <span class="bcp14">MUST NOT</span> include internal IP addresses/prefixes and/or port
      numbers; instead, external addresses/prefixes and/or port numbers as
      assigned by the translator <span class="bcp14">MUST</span> be used. This document does not make any
      recommendations about possible translator discovery mechanisms. The
      following are some (non-exhaustive) deployment examples that may be
      considered:<a href="#section-3-17" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3-18.1">Port Control Protocol (PCP) <span>[<a href="#RFC6887" class="xref">RFC6887</a>]</span> or Session Traversal Utilities for NAT
          (STUN) <span>[<a href="#RFC8489" class="xref">RFC8489</a>]</span> may be used by the client to
          retrieve the external addresses/prefixes and/or port numbers.
          Information retrieved by means of PCP or STUN will be used to feed
          the DOTS signal channel messages that will be sent to a DOTS
          server.<a href="#section-3-18.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-3-18.2">A DOTS gateway may be co-located with the translator. The DOTS
          gateway will need to update the DOTS messages based upon the local
          translator's binding table.<a href="#section-3-18.2" class="pilcrow">¶</a>
</li>
      </ul>
<div id="back">
<section id="section-3.1">
        <h3 id="name-backward-compatibility-cons">
<a href="#section-3.1" class="section-number selfRef">3.1. </a><a href="#name-backward-compatibility-cons" class="section-name selfRef">Backward Compatibility Considerations</a>
        </h3>
<p id="section-3.1-1">The main changes to <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span> are listed in
        <a href="#changes" class="xref">Appendix A</a>. These modifications are made with the
        constraint to avoid changes to the mapping table defined in Table 5 of
        <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span> (see also <a href="#mapping" class="xref">Section 6</a> of the present document).<a href="#section-3.1-1" class="pilcrow">¶</a></p>
<p id="section-3.1-2">For both legacy <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span> and implementations
        that follow the present specification, a DOTS signal channel attribute
        will thus have the same CBOR key value and CBOR major type. The only
        upgrade that is required to <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span>
        implementations is to handle the CBOR key value range "128-255" as
        comprehension-optional instead of comprehension-required. Note that
        this range is anticipated to be used by the DOTS telemetry <span>[<a href="#I-D.ietf-dots-telemetry" class="xref">DOTS-TELEMETRY</a>]</span> in which the following means
        are used to prevent message processing failure of a DOTS signal
        channel message enriched with telemetry data: (1) DOTS agents use
        dedicated (new) path suffixes (<span><a href="https://datatracker.ietf.org/doc/html/draft-ietf-dots-telemetry-16#section-5" class="relref">Section 5</a> of [<a href="#I-D.ietf-dots-telemetry" class="xref">DOTS-TELEMETRY</a>]</span>) and (2) a DOTS server won't
        include telemetry attributes in its responses unless it is explicitly
        told to do so by a DOTS client (<span><a href="https://datatracker.ietf.org/doc/html/draft-ietf-dots-telemetry-16#section-6.1.2" class="relref">Section 6.1.2</a> of [<a href="#I-D.ietf-dots-telemetry" class="xref">DOTS-TELEMETRY</a>]</span>).<a href="#section-3.1-2" class="pilcrow">¶</a></p>
<p id="section-3.1-3">Future DOTS extensions that request a CBOR value in the range
        "128-255" <span class="bcp14">MUST</span> support means similar to the aforementioned DOTS
        telemetry ones.<a href="#section-3.1-3" class="pilcrow">¶</a></p>
</section>
</div>
</section>
<div id="sig">
<section id="section-4">
      <h2 id="name-dots-signal-channel-message">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-dots-signal-channel-message" class="section-name selfRef">DOTS Signal Channel: Messages &amp; Behaviors</a>
      </h2>
<div id="discover">
<section id="section-4.1">
        <h3 id="name-dots-servers-discovery">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-dots-servers-discovery" class="section-name selfRef">DOTS Server(s) Discovery</a>
        </h3>
<p id="section-4.1-1">This document assumes that DOTS clients are provisioned with the
        reachability information of their DOTS server(s) using any of a
        variety of means (e.g., local configuration or dynamic means, such as
        DHCP <span>[<a href="#RFC8973" class="xref">RFC8973</a>]</span>). The description of such means is
        out of scope of this document.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">Likewise, it is out of the scope of this document to specify the
        behavior to be followed by a DOTS client in order to send DOTS
        requests when multiple DOTS servers are provisioned (e.g., contact all
        DOTS servers, select one DOTS server among the list). Such behavior is
        specified in other documents (e.g., <span>[<a href="#I-D.ietf-dots-multihoming" class="xref">DOTS-MULTIHOMING</a>]</span>).<a href="#section-4.1-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="uri-path">
<section id="section-4.2">
        <h3 id="name-coap-uris">
<a href="#section-4.2" class="section-number selfRef">4.2. </a><a href="#name-coap-uris" class="section-name selfRef">CoAP URIs</a>
        </h3>
<p id="section-4.2-1">The DOTS server <span class="bcp14">MUST</span> support the use of the path prefix of
        "/.well-known/" as defined in <span>[<a href="#RFC8615" class="xref">RFC8615</a>]</span> and the
        registered name of "dots". Each DOTS operation is denoted by a path
        suffix that indicates the intended operation. The operation path
        (<a href="#table1" class="xref">Table 1</a>) is appended to the path prefix to form the
 URI used with a
        CoAP request to perform the desired DOTS operation.<a href="#section-4.2-1" class="pilcrow">¶</a></p>
<span id="name-operations-and-correspondin"></span><div id="table1">
<table class="center" id="table-1">
          <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-operations-and-correspondin" class="selfRef">Operations and Corresponding URIs</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Operation</th>
              <th class="text-left" rowspan="1" colspan="1">Operation Path</th>
              <th class="text-left" rowspan="1" colspan="1">Details</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Mitigation</td>
              <td class="text-left" rowspan="1" colspan="1">/mitigate</td>
              <td class="text-left" rowspan="1" colspan="1">
                <a href="#m_req" class="xref">Section 4.4</a>
</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Session configuration</td>
              <td class="text-left" rowspan="1" colspan="1">/config</td>
              <td class="text-left" rowspan="1" colspan="1">
                <a href="#sigconfig" class="xref">Section 4.5</a>
</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Heartbeat</td>
              <td class="text-left" rowspan="1" colspan="1">/hb</td>
              <td class="text-left" rowspan="1" colspan="1">
                <a href="#hb" class="xref">Section 4.7</a>
</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
<div id="HE">
<section id="section-4.3">
        <h3 id="name-happy-eyeballs-for-dots-sig">
<a href="#section-4.3" class="section-number selfRef">4.3. </a><a href="#name-happy-eyeballs-for-dots-sig" class="section-name selfRef">Happy Eyeballs for DOTS Signal Channel</a>
        </h3>
<p id="section-4.3-1"><span>[<a href="#RFC8612" class="xref">RFC8612</a>]</span> mentions that DOTS agents will have
        to support both connectionless and connection-oriented protocols. As
        such, the DOTS signal channel is designed to operate with DTLS over
        UDP and TLS over TCP. Further, a DOTS client may acquire a list of
        IPv4 and IPv6 addresses (<a href="#discover" class="xref">Section 4.1</a>), each of
        which can be used to contact the DOTS server using UDP and TCP. If no
        list of IPv4 and IPv6 addresses to contact the DOTS server is
        configured (or discovered), the DOTS client adds the IPv4/IPv6
        addresses of its default router to the candidate list to contact the
        DOTS server.<a href="#section-4.3-1" class="pilcrow">¶</a></p>
<p id="section-4.3-2">The following specifies the procedure to follow to select the
        address family and the transport protocol for sending DOTS signal
        channel messages.<a href="#section-4.3-2" class="pilcrow">¶</a></p>
<p id="section-4.3-3">Such a procedure is needed to avoid experiencing long connection
        delays. For example, if an IPv4 path to a DOTS server is functional,
        but the DOTS server's IPv6 path is nonfunctional, a dual-stack DOTS
        client may experience a significant connection delay compared to an
        IPv4-only DOTS client in the same network conditions. The other
        problem is that if a middlebox between the DOTS client and DOTS server
        is configured to block UDP traffic, the DOTS client will fail to
        establish a DTLS association with the DOTS server; consequently, it
        will have to fall back to TLS over TCP, thereby incurring significant
        connection delays.<a href="#section-4.3-3" class="pilcrow">¶</a></p>
<p id="section-4.3-4">To overcome these connection setup problems, the DOTS client
        attempts to connect to its DOTS server(s) using both IPv6 and IPv4,
        and it tries both DTLS over UDP and TLS over TCP following a DOTS
        Happy Eyeballs approach. To some extent, this approach is similar to
        the Happy Eyeballs mechanism defined in <span>[<a href="#RFC8305" class="xref">RFC8305</a>]</span>. The connection attempts are performed by the
        DOTS client when it initializes or, in general, when it has to select
        an address family and transport to contact its DOTS server. The
        results of the Happy Eyeballs procedure are used by the DOTS client
        for sending its subsequent messages to the DOTS server. The
        differences in behavior with respect to the Happy Eyeballs mechanism
        <span>[<a href="#RFC8305" class="xref">RFC8305</a>]</span> are listed below:<a href="#section-4.3-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.3-5.1">The order of preference of the DOTS signal channel address
            family and transport protocol (most preferred first) is the
            following: UDP over IPv6, UDP over IPv4, TCP over IPv6, and
            finally TCP over IPv4. This order adheres to the address
            preference order specified in <span>[<a href="#RFC6724" class="xref">RFC6724</a>]</span> and
            the DOTS signal channel preference that promotes the use of UDP
            over TCP (to avoid TCP's head of line blocking).<a href="#section-4.3-5.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-4.3-5.2">After successfully establishing a connection, the DOTS client
            <span class="bcp14">MUST</span> cache information regarding the outcome of each connection
            attempt for a specific time period; it uses that information to
            avoid thrashing the network with subsequent attempts. The cached
            information is flushed when its age exceeds a specific time period
            on the order of few minutes (e.g., 10 min). Typically, if the DOTS
            client has to reestablish the connection with the same DOTS server
            within a few seconds after the Happy Eyeballs mechanism is
            completed, caching avoids thrashing the network especially in the
            presence of DDoS attack traffic.<a href="#section-4.3-5.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-4.3-5.3">If a DOTS signal channel session is established with TLS (but
            DTLS failed), the DOTS client periodically repeats the mechanism
            to discover whether DOTS signal channel messages with DTLS over
            UDP become available from the DOTS server; this is so the DOTS
            client can migrate the DOTS signal channel from TCP to UDP. Such
            probing <span class="bcp14">SHOULD NOT</span> be done more frequently than every 24 hours and
            <span class="bcp14">MUST NOT</span> be done more frequently than every 5 minutes.<a href="#section-4.3-5.3" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-4.3-6">When connection attempts are made during an attack, the DOTS client
 <span class="bcp14">SHOULD</span>
        use a "Connection Attempt Delay" <span>[<a href="#RFC8305" class="xref">RFC8305</a>]</span> set to
        100 ms.<a href="#section-4.3-6" class="pilcrow">¶</a></p>
<p id="section-4.3-7">In <a href="#fig_happy_eyeballs" class="xref">Figure 4</a>, the DOTS client
        proceeds with the connection attempts following the rules in <span>[<a href="#RFC8305" class="xref">RFC8305</a>]</span>. In this example, it is assumed that the IPv6
        path is broken and UDP traffic is dropped by a middlebox, but this has
        little impact on the DOTS client because there is not a long delay
        before using IPv4 and TCP.<a href="#section-4.3-7" class="pilcrow">¶</a></p>
<span id="name-dots-happy-eyeballs-sample-"></span><div id="fig_happy_eyeballs">
<figure id="figure-4">
          <div class="artwork art-text alignCenter" id="section-4.3-8.1">
<pre>
+-----------+                                         +-----------+
|DOTS Client|                                         |DOTS Server|
+-----------+                                         +-----------+
      |                                                     |
   T0 |--DTLS ClientHello, IPv6 ----&gt;X                      |
   T1 |--DTLS ClientHello, IPv4 ----&gt;X                      |
   T2 |--TCP SYN, IPv6--------------&gt;X                      |
   T3 |--TCP SYN, IPv4-------------------------------------&gt;|
      |&lt;-TCP SYNACK-----------------------------------------|
      |--TCP ACK-------------------------------------------&gt;|
      |&lt;------------Establish TLS Session------------------&gt;|
      |----------------DOTS signal-------------------------&gt;|
      |                                                     |

 Note:
  * Retransmission messages are not shown.
  * T1-T0=T2-T1=T3-T2= Connection Attempt Delay.
</pre>
</div>
<figcaption><a href="#figure-4" class="selfRef">Figure 4</a>:
<a href="#name-dots-happy-eyeballs-sample-" class="selfRef">DOTS Happy Eyeballs (Sample Flow)</a>
          </figcaption></figure>
</div>
<p id="section-4.3-9">A single DOTS signal channel between DOTS agents can be used to
        exchange multiple DOTS signal messages. To reduce DOTS client and DOTS
        server workload, DOTS clients <span class="bcp14">SHOULD</span> reuse the (D)TLS session.<a href="#section-4.3-9" class="pilcrow">¶</a></p>
</section>
</div>
<div id="m_req">
<section id="section-4.4">
        <h3 id="name-dots-mitigation-methods">
<a href="#section-4.4" class="section-number selfRef">4.4. </a><a href="#name-dots-mitigation-methods" class="section-name selfRef">DOTS Mitigation Methods</a>
        </h3>
<p id="section-4.4-1">The following methods are used by a DOTS client to request,
        retrieve, or withdraw the status of mitigation requests:<a href="#section-4.4-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4-2">
          <dt id="section-4.4-2.1">PUT:</dt>
          <dd style="margin-left: 4.5em" id="section-4.4-2.2">DOTS clients use the PUT method to request
            mitigation from a DOTS server (<a href="#post" class="xref">Section 4.4.1</a>).
            During active mitigation, DOTS clients may use PUT requests to
            carry mitigation efficacy updates to the DOTS server (<a href="#put" class="xref">Section 4.4.3</a>).<a href="#section-4.4-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.4-2.3">GET:</dt>
          <dd style="margin-left: 4.5em" id="section-4.4-2.4">DOTS clients may use the GET method to retrieve
            the list of its mitigations maintained by a DOTS server (<a href="#get" class="xref">Section 4.4.2</a>) or to receive asynchronous DOTS server
            status messages (<a href="#obs" class="xref">Section 4.4.2.1</a>).<a href="#section-4.4-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.4-2.5">DELETE:</dt>
          <dd style="margin-left: 4.5em" id="section-4.4-2.6">DOTS clients use the DELETE method to
            withdraw a request for mitigation from a DOTS server (<a href="#del" class="xref">Section 4.4.4</a>).<a href="#section-4.4-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-4.4-3">Mitigation request and response messages are marked as
        Non-confirmable messages (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-2.2" class="relref">Section 2.2</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>).<a href="#section-4.4-3" class="pilcrow">¶</a></p>
<p id="section-4.4-4">DOTS agents <span class="bcp14">MUST NOT</span> send more than one UDP datagram per round-trip
        time (RTT) to the peer DOTS agent on average following the data
        transmission guidelines discussed in <span><a href="https://www.rfc-editor.org/rfc/rfc8085#section-3.1.3" class="relref">Section 3.1.3</a> of [<a href="#RFC8085" class="xref">RFC8085</a>]</span>.<a href="#section-4.4-4" class="pilcrow">¶</a></p>
<p id="section-4.4-5">Requests marked by the DOTS client as Non-confirmable messages are
        sent at regular intervals until a response is received from the DOTS
        server. If the DOTS client cannot maintain an RTT estimate, it <span class="bcp14">MUST NOT</span> send more than one Non-confirmable request every 3 seconds and
        <span class="bcp14">SHOULD</span> use an even less aggressive rate whenever possible (case 2 in
        <span><a href="https://www.rfc-editor.org/rfc/rfc8085#section-3.1.3" class="relref">Section 3.1.3</a> of [<a href="#RFC8085" class="xref">RFC8085</a>]</span>). Mitigation requests
        <span class="bcp14">MUST NOT</span> be delayed because of checks on probing rate 
        (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.7" class="relref">Section 4.7</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>).<a href="#section-4.4-5" class="pilcrow">¶</a></p>
<p id="section-4.4-6">JSON encoding of YANG-modeled data <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span>
        is used to illustrate the various methods defined in the following
        subsections. Also, the examples use the Labels defined in Sections
        <a href="#sc" class="xref">10.6.2</a>, <a href="#cs" class="xref">10.6.3</a>, <a href="#cc" class="xref">10.6.4</a>, and
        <a href="#as" class="xref">10.6.5</a>.<a href="#section-4.4-6" class="pilcrow">¶</a></p>
<p id="section-4.4-7">The DOTS client <span class="bcp14">MUST</span> authenticate itself to the DOTS server (<a href="#mutauth" class="xref">Section 8</a>). The DOTS server <span class="bcp14">MAY</span> use the algorithm
        presented in <span><a href="https://www.rfc-editor.org/rfc/rfc7589#section-7" class="relref">Section 7</a> of [<a href="#RFC7589" class="xref">RFC7589</a>]</span> to derive the
        DOTS client identity or username from the client certificate. The DOTS
        client identity allows the DOTS server to accept mitigation requests
        with scopes that the DOTS client is authorized to manage.<a href="#section-4.4-7" class="pilcrow">¶</a></p>
<div id="post">
<section id="section-4.4.1">
          <h4 id="name-request-mitigation">
<a href="#section-4.4.1" class="section-number selfRef">4.4.1. </a><a href="#name-request-mitigation" class="section-name selfRef">Request Mitigation</a>
          </h4>
<section id="section-4.4.1.1">
            <h5 id="name-building-mitigation-request">
<a href="#section-4.4.1.1" class="section-number selfRef">4.4.1.1. </a><a href="#name-building-mitigation-request" class="section-name selfRef">Building Mitigation Requests</a>
            </h5>
<p id="section-4.4.1.1-1">When a DOTS client requires mitigation for some reason, the
            DOTS client uses the CoAP PUT method to send a mitigation request
            to its DOTS server(s) (Figures <a href="#Figure1" class="xref">5</a> and <a href="#Figure1c" class="xref">6</a>).<a href="#section-4.4.1.1-1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-2">If a DOTS client is entitled to solicit the DOTS service, the
            DOTS server enables mitigation on behalf of the DOTS client by
            communicating the DOTS client's request to a mitigator (which may
            be co-located with the DOTS server) and relaying the feedback of
            the thus-selected mitigator to the requesting DOTS client.<a href="#section-4.4.1.1-2" class="pilcrow">¶</a></p>
<span id="name-put-to-convey-dots-mitigati"></span><div id="Figure1">
<figure id="figure-5">
              <div id="section-4.4.1.1-3.1">
<pre class="sourcecode">
  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=123"
  Content-Format: "application/dots+cbor"

  {
    ...
  }
</pre>
</div>
<figcaption><a href="#figure-5" class="selfRef">Figure 5</a>:
<a href="#name-put-to-convey-dots-mitigati" class="selfRef">PUT to Convey DOTS Mitigation Requests</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.1-4">The order of the Uri-Path options is important, as it defines
            the CoAP resource. In particular, 'mid' <span class="bcp14">MUST</span> follow 'cuid'.<a href="#section-4.4.1.1-4" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-5">The additional Uri-Path parameters to those defined in <a href="#uri-path" class="xref">Section 4.2</a> are as follows:<a href="#section-4.4.1.1-5" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.1-6">
              <dt id="section-4.4.1.1-6.1">cuid:</dt>
              <dd style="margin-left: 3.5em" id="section-4.4.1.1-6.2">
                <p id="section-4.4.1.1-6.2.1">Stands for Client Unique Identifier. A
                globally unique identifier that is meant to prevent collisions
                among DOTS clients, especially those from the same domain. It
                <span class="bcp14">MUST</span> be generated by DOTS clients.<a href="#section-4.4.1.1-6.2.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.2">For
                the reasons discussed in <a href="#motiv" class="xref">Appendix B</a>,
                implementations <span class="bcp14">SHOULD</span> set 'cuid' using the following
                procedure: first, the DOTS client inputs one of the following
                into the SHA-256 <span>[<a href="#RFC6234" class="xref">RFC6234</a>]</span> cryptographic
                hash: the DER-encoded ASN.1 representation of the Subject
                Public Key Info (SPKI) of its X.509 certificate <span>[<a href="#RFC5280" class="xref">RFC5280</a>]</span>, its raw public key <span>[<a href="#RFC7250" class="xref">RFC7250</a>]</span>, the "Pre-Shared Key (PSK) identity"
                it uses in the TLS 1.2 ClientKeyExchange message, or the
                "identity" it uses in the "pre_shared_key" TLS 1.3 extension.
                Then, the output of the cryptographic hash algorithm is
                truncated to 16 bytes; truncation is done by stripping off the
                final 16 bytes. The truncated output is base64url encoded
                (<span><a href="https://www.rfc-editor.org/rfc/rfc4648#section-5" class="relref">Section 5</a> of [<a href="#RFC4648" class="xref">RFC4648</a>]</span>) with the two
                trailing "=" removed from the encoding, and the resulting
                value used as the 'cuid'.<a href="#section-4.4.1.1-6.2.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.3">The 'cuid'
                is intended to be stable when communicating with a given DOTS
                server, i.e., the 'cuid' used by a DOTS client <span class="bcp14">SHOULD NOT</span>
                change over time. Distinct 'cuid' values <span class="bcp14">MAY</span> be used by a
                single DOTS client per DOTS server.<a href="#section-4.4.1.1-6.2.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.4">If a DOTS client has to change its 'cuid' for
                some reason, it <span class="bcp14">MUST NOT</span> do so when mitigations are still
                active for the old 'cuid'. The 'cuid' <span class="bcp14">SHOULD</span> be 22 characters
                to avoid DOTS signal message fragmentation over UDP.
                Furthermore, if that DOTS client created aliases and filtering
                entries at the DOTS server by means of the DOTS data channel,
                it <span class="bcp14">MUST</span> delete all the entries bound to the old 'cuid' and
                reinstall them using the new 'cuid'.<a href="#section-4.4.1.1-6.2.4" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.5">DOTS servers <span class="bcp14">MUST</span> return 4.09 (Conflict)
                error code to a DOTS peer to notify that the 'cuid' is already
                in use by another DOTS client. Upon receipt of that error
                code, a new 'cuid' <span class="bcp14">MUST</span> be generated by the DOTS peer (e.g.,
                using <span>[<a href="#RFC4122" class="xref">RFC4122</a>]</span>).<a href="#section-4.4.1.1-6.2.5" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.6">Client-domain DOTS gateways <span class="bcp14">MUST</span> handle
                'cuid' collision directly, and it is <span class="bcp14">RECOMMENDED</span> that 'cuid'
                collision is handled directly by server-domain DOTS
                gateways.<a href="#section-4.4.1.1-6.2.6" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.7">DOTS gateways <span class="bcp14">MAY</span> rewrite
                the 'cuid' used by peer DOTS clients. Triggers for such
                rewriting are out of scope.<a href="#section-4.4.1.1-6.2.7" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.2.8">This is a mandatory Uri-Path parameter.<a href="#section-4.4.1.1-6.2.8" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-6.3">mid:</dt>
              <dd style="margin-left: 3.5em" id="section-4.4.1.1-6.4">
                <p id="section-4.4.1.1-6.4.1">Identifier for the mitigation request
                represented with an integer. This identifier <span class="bcp14">MUST</span> be unique
                for each mitigation request bound to the DOTS client, i.e.,
                the 'mid' parameter value in the mitigation request needs to
                be unique (per 'cuid' and DOTS server) relative to the 'mid'
                parameter values of active mitigation requests conveyed from
                the DOTS client to the DOTS server.<a href="#section-4.4.1.1-6.4.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.4.2">In
                order to handle out-of-order delivery of mitigation requests,
                'mid' values <span class="bcp14">MUST</span> increase monotonically.<a href="#section-4.4.1.1-6.4.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.4.3">If the 'mid' value has reached 3/4 of (2<sup>(32)</sup>
                - 1) (i.e., 3221225471) and no attack is detected, the DOTS
                client <span class="bcp14">MUST</span> reset 'mid' to 0 to handle 'mid' rollover. If the
                DOTS client maintains mitigation requests with preconfigured
                scopes, it <span class="bcp14">MUST</span> recreate them with the 'mid' restarting at
                0.<a href="#section-4.4.1.1-6.4.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.4.4">This identifier <span class="bcp14">MUST</span> be generated
                by the DOTS client.<a href="#section-4.4.1.1-6.4.4" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-6.4.5">This is a
                mandatory Uri-Path parameter.<a href="#section-4.4.1.1-6.4.5" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
</dl>
<p id="section-4.4.1.1-7">'cuid' and 'mid' <span class="bcp14">MUST NOT</span> appear in the PUT request message
            body (<a href="#Figure1c" class="xref">Figure 6</a>). The schema in <a href="#Figure1c" class="xref">Figure 6</a> uses the types defined in <a href="#mapping" class="xref">Section 6</a>. Note that this figure (and other similar
            figures depicting a schema) are non-normative sketches of the
            structure of the message.<a href="#section-4.4.1.1-7" class="pilcrow">¶</a></p>
<span id="name-put-to-convey-dots-mitigatio"></span><div id="Figure1c">
<figure id="figure-6">
              <div id="section-4.4.1.1-8.1">
<pre class="sourcecode">
  {
    "ietf-dots-signal-channel:mitigation-scope": {
      "scope": [
        {
          "target-prefix": [
             "string"
           ],
          "target-port-range": [
             {
               "lower-port": number,
               "upper-port": number
             }
           ],
           "target-protocol": [
             number
           ],
           "target-fqdn": [
             "string"
           ],
           "target-uri": [
             "string"
           ],
           "alias-name": [
             "string"
           ],
          "lifetime": number,
          "trigger-mitigation": true|false
        }
      ]
    }
  }
</pre>
</div>
<figcaption><a href="#figure-6" class="selfRef">Figure 6</a>:
<a href="#name-put-to-convey-dots-mitigatio" class="selfRef">PUT to Convey DOTS Mitigation Requests (Message Body Schema)</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.1-9">The parameters in the CBOR body (<a href="#Figure1c" class="xref">Figure 6</a>) of the PUT request are described
            below:<a href="#section-4.4.1.1-9" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.1-10">
              <dt id="section-4.4.1.1-10.1">target-prefix:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.2">
                <p id="section-4.4.1.1-10.2.1">A list of prefixes identifying
                resources under attack. Prefixes are represented using
                Classless Inter-Domain Routing (CIDR) notation <span>[<a href="#RFC4632" class="xref">RFC4632</a>]</span>.<a href="#section-4.4.1.1-10.2.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.2.2">The prefix
                length must be less than or equal to 32 for IPv4 and 128 for
                IPv6.<a href="#section-4.4.1.1-10.2.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.2.3">The prefix list <span class="bcp14">MUST NOT</span> include
                broadcast, loopback, or multicast addresses. These addresses
                are considered to be invalid values. In addition, the DOTS
                server <span class="bcp14">MUST</span> validate that target prefixes are within the scope
                of the DOTS client domain. Other validation checks may be
                supported by DOTS servers.<a href="#section-4.4.1.1-10.2.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.2.4">This is an optional attribute.<a href="#section-4.4.1.1-10.2.4" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.3">target-port-range:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.4">
                <p id="section-4.4.1.1-10.4.1">A list of port numbers bound to resources under attack.<a href="#section-4.4.1.1-10.4.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.4.2">A port
                range is defined by two bounds: a lower port number
                ('lower-port') and an upper port number ('upper-port'). When
                only 'lower-port' is present, it represents a single port
                number.<a href="#section-4.4.1.1-10.4.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.4.3">For TCP, UDP, Stream Control
                Transmission Protocol (SCTP) <span>[<a href="#RFC4960" class="xref">RFC4960</a>]</span>,
                or Datagram Congestion Control Protocol (DCCP) <span>[<a href="#RFC4340" class="xref">RFC4340</a>]</span>, a range of ports can be, for
                example, 0-1023, 1024-65535, or 1024-49151.<a href="#section-4.4.1.1-10.4.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.4.4">This is an optional attribute.<a href="#section-4.4.1.1-10.4.4" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.5">target-protocol:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.6">
                <p id="section-4.4.1.1-10.6.1">A list of protocols involved in
                an attack. Values are integers in the range of 0 to 255. See
                <span>[<a href="#IANA-Proto" class="xref">IANA-Proto</a>]</span> for common values.<a href="#section-4.4.1.1-10.6.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.6.2">If 'target-protocol' is not specified, then
                the request applies to any protocol.<a href="#section-4.4.1.1-10.6.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.6.3">This is an optional attribute.<a href="#section-4.4.1.1-10.6.3" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.7">target-fqdn:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.8">
                <p id="section-4.4.1.1-10.8.1">A list of Fully Qualified Domain
                Names (FQDNs) identifying resources under attack <span>[<a href="#RFC8499" class="xref">RFC8499</a>]</span>.<a href="#section-4.4.1.1-10.8.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.8.2">How a name
                is passed to an underlying name resolution library is
                implementation and deployment specific. Nevertheless, once the
                name is resolved into one or multiple IP addresses, DOTS
                servers <span class="bcp14">MUST</span> apply the same validation checks as those for
                'target-prefix'. These validation checks are reiterated by
                DOTS servers each time a name is passed to an underlying name
                resolution library (e.g., upon expiry of DNS TTL).<a href="#section-4.4.1.1-10.8.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.8.3">The use of FQDNs may be suboptimal
                because:<a href="#section-4.4.1.1-10.8.3" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.4.1.1-10.8.4.1">It induces both an extra load and increased delays on
                    the DOTS server to handle and manage DNS resolution
                    requests.<a href="#section-4.4.1.1-10.8.4.1" class="pilcrow">¶</a>
</li>
                  <li class="normal" id="section-4.4.1.1-10.8.4.2">It does not guarantee that the DOTS server will resolve
                    a name to the same IP addresses that the DOTS client
                    does.<a href="#section-4.4.1.1-10.8.4.2" class="pilcrow">¶</a>
</li>
                </ul>
<p id="section-4.4.1.1-10.8.5">This is an optional
                attribute.<a href="#section-4.4.1.1-10.8.5" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.9">target-uri:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.10">
                <p id="section-4.4.1.1-10.10.1">A list of URIs <span>[<a href="#RFC3986" class="xref">RFC3986</a>]</span> identifying
 resources under attack.<a href="#section-4.4.1.1-10.10.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.10.2">The same validation checks used for
                'target-fqdn' <span class="bcp14">MUST</span> be followed by DOTS servers to validate a
                target URI.<a href="#section-4.4.1.1-10.10.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.10.3">This is an optional
                attribute.<a href="#section-4.4.1.1-10.10.3" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.11">alias-name:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.12">
                <p id="section-4.4.1.1-10.12.1">A list of aliases of resources for
                which the mitigation is requested. Aliases can be created
                using the DOTS data channel (<span><a href="https://www.rfc-editor.org/rfc/rfc8783#section-6.1" class="relref">Section 6.1</a> of [<a href="#RFC8783" class="xref">RFC8783</a>]</span>), direct configuration, or other
                means.<a href="#section-4.4.1.1-10.12.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.12.2">An alias is used in subsequent
                signal channel exchanges to refer more efficiently to the
                resources under attack.<a href="#section-4.4.1.1-10.12.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.12.3">This is an
                optional attribute.<a href="#section-4.4.1.1-10.12.3" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.13">lifetime:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.14">
                <p id="section-4.4.1.1-10.14.1">Lifetime of the mitigation request in
                seconds. The <span class="bcp14">RECOMMENDED</span> lifetime of a mitigation request is
                3600 seconds; this value was chosen to be long enough so that
                refreshing is not typically a burden on the DOTS client while
                still making the request expire in a timely manner when the
                client has unexpectedly quit. DOTS clients <span class="bcp14">MUST</span> include this
                parameter in their mitigation requests.<a href="#section-4.4.1.1-10.14.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.14.2">A lifetime of '0' in a mitigation request is
                an invalid value.<a href="#section-4.4.1.1-10.14.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.14.3">A lifetime of
                negative one (-1) indicates indefinite lifetime for the
                mitigation request. The DOTS server <span class="bcp14">MAY</span> refuse an indefinite
                lifetime, for policy reasons; the granted lifetime value is
                returned in the response. DOTS clients <span class="bcp14">MUST</span> be prepared to not
                be granted mitigations with indefinite lifetimes.<a href="#section-4.4.1.1-10.14.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.14.4">The DOTS server <span class="bcp14">MUST</span> always indicate the
                actual lifetime in the response and the remaining lifetime in
                status messages sent to the DOTS client.<a href="#section-4.4.1.1-10.14.4" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.14.5">Upon the expiry of the negotiated lifetime
                (i.e., the remaining lifetime reaches '0'), and if the request
                is not refreshed by the DOTS client, the mitigation request is
                removed by the DOTS server. The request can be refreshed by
                sending the same request again.<a href="#section-4.4.1.1-10.14.5" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.14.6">This
                is a mandatory attribute.<a href="#section-4.4.1.1-10.14.6" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-4.4.1.1-10.15">trigger-mitigation:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.1-10.16">
                <p id="section-4.4.1.1-10.16.1">If the parameter value is
                set to 'false', DDoS mitigation will not be triggered for the
                mitigation request unless the DOTS signal channel session is
                lost.<a href="#section-4.4.1.1-10.16.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.16.2">If the DOTS client ceases to
                respond to heartbeat messages, the DOTS server can detect that
                the DOTS signal channel session is lost. More details are
                discussed in <a href="#hb" class="xref">Section 4.7</a>.<a href="#section-4.4.1.1-10.16.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.16.3">The default value of the parameter is 'true'
                (that is, the mitigation starts immediately). If
                'trigger-mitigation' is not present in a request, this is
                equivalent to receiving a request with 'trigger-mitigation'
                set to 'true'.<a href="#section-4.4.1.1-10.16.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-10.16.4">This is an optional
                attribute.<a href="#section-4.4.1.1-10.16.4" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
</dl>
<p id="section-4.4.1.1-11">Because of the complexity of handling partial failure cases,
            this specification does not allow the inclusion of multiple
            mitigation requests in the same PUT request. Concretely, a DOTS
            client <span class="bcp14">MUST NOT</span> include multiple entries in the 'scope' array of
            the same PUT request.<a href="#section-4.4.1.1-11" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-12">FQDN and URI mitigation scopes may be thought of as a form of
            scope alias, in which the addresses associated with the domain
            name or URI (as resolved by the DOTS server) represent the scope
            of the mitigation. Particularly, the IP addresses to which the
            host subcomponent of authority component of a URI resolves
            represent the 'target-prefix', the URI scheme represents the
            'target-protocol', and the port subcomponent of authority component of
            a URI represents the 'target-port-range'. If the optional port
            information is not present in the authority component, the default
            port defined for the URI scheme represents the 'target-port'.<a href="#section-4.4.1.1-12" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-13">In the PUT request, at least one of the attributes
            'target-prefix', 'target-fqdn','target-uri', or 'alias-name' <span class="bcp14">MUST</span>
            be present.<a href="#section-4.4.1.1-13" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-14">Attributes and Uri-Path parameters with empty values <span class="bcp14">MUST NOT</span>
            be present in a request, as an empty value will render the entire
            request invalid.<a href="#section-4.4.1.1-14" class="pilcrow">¶</a></p>
<p id="section-4.4.1.1-15"><a href="#Figure2" class="xref">Figure 7</a> shows a PUT request example to
            signal that servers 2001:db8:6401::1 and 2001:db8:6401::2 are
            receiving attack traffic on TCP port numbers 80, 8080, and 443.
            The presence of 'cdid' indicates that a server-domain DOTS gateway
            has modified the initial PUT request sent by the DOTS client. Note
            that 'cdid' <span class="bcp14">MUST NOT</span> appear in the PUT request message body.<a href="#section-4.4.1.1-15" class="pilcrow">¶</a></p>
<span id="name-put-for-dots-mitigation-req"></span><div id="Figure2">
<figure id="figure-7">
              <div id="section-4.4.1.1-16.1">
<pre class="sourcecode">
  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cdid=7eeaf349529eb55ed50113"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=123"
  Content-Format: "application/dots+cbor"

  {
    "ietf-dots-signal-channel:mitigation-scope": {
      "scope": [
        {
          "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
           ],
          "target-port-range": [
            {
              "lower-port": 80
            },
            {
              "lower-port": 443
            },
            {
               "lower-port": 8080
            }
           ],
           "target-protocol": [
             6
           ],
          "lifetime": 3600
        }
      ]
    }
  }
</pre>
</div>
<figcaption><a href="#figure-7" class="selfRef">Figure 7</a>:
<a href="#name-put-for-dots-mitigation-req" class="selfRef">PUT for DOTS Mitigation Request (An Example)</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.1-17">The corresponding CBOR encoding format for the payload is shown
            in <a href="#Figure2a" class="xref">Figure 8</a>.<a href="#section-4.4.1.1-17" class="pilcrow">¶</a></p>
<span id="name-put-for-dots-mitigation-requ"></span><div id="Figure2a">
<figure id="figure-8">
              <div id="section-4.4.1.1-18.1">
<pre class="sourcecode lang-cbor">
   A1                                      # map(1)
      01                                   # unsigned(1)
      A1                                   # map(1)
         02                                # unsigned(2)
         81                                # array(1)
            A4                             # map(4)
               06                          # unsigned(6)
               82                          # array(2)
                  74                       # text(20)
                     323030313A6462383A363430313A3A312F313238
                  74                       # text(20)
                     323030313A6462383A363430313A3A322F313238
               07                          # unsigned(7)
               83                          # array(3)
                  A1                       # map(1)
                     08                    # unsigned(8)
                     18 50                 # unsigned(80)
                  A1                       # map(1)
                     08                    # unsigned(8)
                     19 01BB               # unsigned(443)
                  A1                       # map(1)
                     08                    # unsigned(8)
                     19 1F90               # unsigned(8080)
               0A                          # unsigned(10)
               81                          # array(1)
                  06                       # unsigned(6)
               0E                          # unsigned(14)
               19 0E10                     # unsigned(3600)
</pre>
</div>
<figcaption><a href="#figure-8" class="selfRef">Figure 8</a>:
<a href="#name-put-for-dots-mitigation-requ" class="selfRef">PUT for DOTS Mitigation Request (CBOR)</a>
              </figcaption></figure>
</div>
</section>
<section id="section-4.4.1.2">
            <h5 id="name-server-domain-dots-gateways">
<a href="#section-4.4.1.2" class="section-number selfRef">4.4.1.2. </a><a href="#name-server-domain-dots-gateways" class="section-name selfRef">Server-Domain DOTS Gateways</a>
            </h5>
<p id="section-4.4.1.2-1">In deployments where server-domain DOTS gateways are enabled,
            identity information about the origin source client domain
            ('cdid') <span class="bcp14">SHOULD</span> be propagated to the DOTS server. That information
            is meant to assist the DOTS server in enforcing some policies, such
            as grouping DOTS clients that belong to the same DOTS domain,
            limiting the number of DOTS requests, and identifying the
            mitigation scope. These policies can be enforced per client, per
            client domain, or both. Also, the identity information may be used
            for auditing and debugging purposes.<a href="#section-4.4.1.2-1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-2"><a href="#Figure1a" class="xref">Figure 9</a> shows an example of a request
            relayed by a server-domain DOTS gateway.<a href="#section-4.4.1.2-2" class="pilcrow">¶</a></p>
<span id="name-put-for-dots-mitigation-reque"></span><div id="Figure1a">
<figure id="figure-9">
              <div id="section-4.4.1.2-3.1">
<pre class="sourcecode">
  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cdid=7eeaf349529eb55ed50113"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=123"
  Content-Format: "application/dots+cbor"

  {
    ...
  }
</pre>
</div>
<figcaption><a href="#figure-9" class="selfRef">Figure 9</a>:
<a href="#name-put-for-dots-mitigation-reque" class="selfRef">PUT for DOTS Mitigation Request as Relayed by a DOTS Gateway</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.2-4">A server-domain DOTS gateway <span class="bcp14">SHOULD</span> add the following Uri-Path
            parameter:<a href="#section-4.4.1.2-4" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.2-5">
              <dt id="section-4.4.1.2-5.1">cdid:</dt>
              <dd style="margin-left: 3.5em" id="section-4.4.1.2-5.2">
                <p id="section-4.4.1.2-5.2.1">Stands for Client Domain Identifier. The
                'cdid' is conveyed by a server-domain DOTS gateway to
                propagate the source domain identity from the gateway's
                client-facing side to the gateway's server-facing side and
                from the gateway's server-facing side to the DOTS server.
                'cdid' may be used by the final DOTS server for policy-enforcement 
 purposes (e.g., enforce a quota on filtering
                rules). These policies are deployment specific.<a href="#section-4.4.1.2-5.2.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.2">Server-domain DOTS gateways <span class="bcp14">SHOULD</span> support a
                configuration option to instruct whether the 'cdid' parameter is
                to be inserted.<a href="#section-4.4.1.2-5.2.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.3">In order to
                accommodate deployments that require enforcing per-client
                policies, per-client domain policies, or a combination
                thereof, server-domain DOTS gateways instructed to insert the
                'cdid' parameter <span class="bcp14">MUST</span> supply the SPKI hash of the DOTS client
                X.509 certificate, the DOTS client raw public key, or the hash
                of the "PSK identity" in the 'cdid', following the same rules
                for generating the hash conveyed in 'cuid', which is then used
                by the ultimate DOTS server to determine the corresponding
                client's domain. The 'cdid' generated by a server-domain
                gateway is likely to be the same as the 'cuid' except the case
                in which the DOTS message was relayed by a client-domain DOTS
                gateway or the 'cuid' was generated by a rogue DOTS
                client.<a href="#section-4.4.1.2-5.2.3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.4">If a DOTS client is
                provisioned, for example, with distinct certificates to use to
                peer with distinct server-domain DOTS gateways that peer to
                the same DOTS server, distinct 'cdid' values may be supplied
                by the server-domain DOTS gateways to the server. The ultimate
                DOTS server <span class="bcp14">MUST</span> treat those 'cdid' values as equivalent.<a href="#section-4.4.1.2-5.2.4" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.5">The 'cdid' attribute <span class="bcp14">MUST NOT</span> be
                generated and included by DOTS clients.<a href="#section-4.4.1.2-5.2.5" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.6">DOTS servers <span class="bcp14">MUST</span> ignore 'cdid' attributes
                that are directly supplied by source DOTS clients or
                client-domain DOTS gateways. This implies that first
                server-domain DOTS gateways <span class="bcp14">MUST</span> strip 'cdid' attributes
                supplied by DOTS clients. DOTS servers <span class="bcp14">SHOULD</span> support a
                configuration parameter to identify DOTS gateways that are
                trusted to supply 'cdid' attributes.<a href="#section-4.4.1.2-5.2.6" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.7">Only single-valued 'cdid' are defined in this
                document. That is, only the first on-path server-domain DOTS
                gateway can insert a 'cdid' value. This specification does not
                allow multiple server-domain DOTS gateways, whenever involved
                in the path, to insert a 'cdid' value for each server-domain
                gateway.<a href="#section-4.4.1.2-5.2.7" class="pilcrow">¶</a></p>
<p id="section-4.4.1.2-5.2.8">This is an optional
                Uri-Path. When present, 'cdid' <span class="bcp14">MUST</span> be positioned before
                'cuid'.<a href="#section-4.4.1.2-5.2.8" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
</dl>
<p id="section-4.4.1.2-6">A DOTS gateway <span class="bcp14">SHOULD</span> add the CoAP Hop-Limit Option <span>[<a href="#RFC8768" class="xref">RFC8768</a>]</span>.<a href="#section-4.4.1.2-6" class="pilcrow">¶</a></p>
</section>
<div id="pro-mit-req">
<section id="section-4.4.1.3">
            <h5 id="name-processing-mitigation-reque">
<a href="#section-4.4.1.3" class="section-number selfRef">4.4.1.3. </a><a href="#name-processing-mitigation-reque" class="section-name selfRef">Processing Mitigation Requests</a>
            </h5>
<p id="section-4.4.1.3-1">The DOTS server couples the DOTS signal and data channel
            sessions using the DOTS client identity and optionally the 'cdid'
            parameter value, so the DOTS server can validate whether the
            aliases conveyed in the mitigation request were indeed created by
            the same DOTS client using the DOTS data channel session. If the
            aliases were not created by the DOTS client, the DOTS server <span class="bcp14">MUST</span>
            return 4.00 (Bad Request) in the response.<a href="#section-4.4.1.3-1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-2">The DOTS server couples the DOTS signal channel sessions using
            the DOTS client identity and optionally the 'cdid' parameter
            value, and the DOTS server uses 'mid' and 'cuid' Uri-Path
            parameter values to detect duplicate mitigation requests. If the
            mitigation request contains the 'alias-name' and other parameters
            identifying the target resources (such as 'target-prefix',
            'target-port-range', 'target-fqdn', or 'target-uri'), the DOTS
            server appends the parameter values associated with the
            'alias-name' with the corresponding parameter values in
            'target-prefix', 'target-port-range', 'target-fqdn', or
            'target-uri'.<a href="#section-4.4.1.3-2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-3">The DOTS server indicates the result of processing the PUT
            request using CoAP Response Codes. CoAP 2.xx codes are success.
            CoAP 4.xx codes are some sort of invalid requests (client errors).
            CoAP 5.xx codes are returned if the DOTS server is in an error
            state or is currently unavailable to provide mitigation in
            response to the mitigation request from the DOTS client.<a href="#section-4.4.1.3-3" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-4"><a href="#put_response" class="xref">Figure 10</a> shows an example response
            to a PUT request that is successfully processed by a DOTS server
            (i.e., CoAP 2.xx Response Codes). This version of the
            specification forbids 'cuid' and 'cdid' (if used) to be returned
            in a response message body.<a href="#section-4.4.1.3-4" class="pilcrow">¶</a></p>
<span id="name-2xx-response-body"></span><div id="put_response">
<figure id="figure-10">
              <div id="section-4.4.1.3-5.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:mitigation-scope": {
     "scope": [
        {
          "mid": 123,
          "lifetime": 3600
        }
      ]
   }
}
</pre>
</div>
<figcaption><a href="#figure-10" class="selfRef">Figure 10</a>:
<a href="#name-2xx-response-body" class="selfRef">2.xx Response Body</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.3-6">If the request is missing a mandatory attribute, does not
            include 'cuid' or 'mid' Uri-Path options, includes multiple
            'scope' parameters, or contains invalid or unknown parameters, the
            DOTS server <span class="bcp14">MUST</span> reply with 4.00 (Bad Request). DOTS agents can
            safely ignore comprehension-optional parameters they don't
            understand (<a href="#format" class="xref">Section 10.6.1.1</a>).<a href="#section-4.4.1.3-6" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-7">A DOTS server that receives a mitigation request with a
            'lifetime' set to '0' <span class="bcp14">MUST</span> reply with a 4.00 (Bad Request).<a href="#section-4.4.1.3-7" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-8">If the DOTS server does not find the 'mid' parameter value
            conveyed in the PUT request in its configuration data, it <span class="bcp14">MAY</span>
            accept the mitigation request by sending back a 2.01 (Created)
            response to the DOTS client; the DOTS server will consequently try
            to mitigate the attack. A DOTS server <span class="bcp14">MAY</span> reject mitigation
            requests when it is near capacity or needs to rate-limit a
            particular client, for example.<a href="#section-4.4.1.3-8" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-9">The relative order of two mitigation requests with the same
            'trigger- mitigation' type from a DOTS client is determined by
            comparing their respective 'mid' values. If two mitigation
            requests with the same 'trigger-mitigation' type have overlapping
            mitigation scopes, the mitigation request with the highest numeric
            'mid' value will override the other mitigation request. Two
            mitigation requests from a DOTS client have overlapping scopes if
            there is a common IP address, IP prefix, FQDN, URI, or alias. To
            avoid maintaining a long list of overlapping mitigation requests
            (i.e., requests with the same 'trigger-mitigation' type and
            overlapping scopes) from a DOTS client and to avoid error-prone
            provisioning of mitigation requests from a DOTS client, the
            overlapped lower numeric 'mid' <span class="bcp14">MUST</span> be automatically deleted and
            no longer available at the DOTS server. For example, if the DOTS
            server receives a mitigation request that overlaps with an
            existing mitigation with a higher numeric 'mid', the DOTS server
            rejects the request by returning 4.09 (Conflict) to the DOTS
            client. The response <span class="bcp14">MUST</span> include enough information for a DOTS
            client to recognize the source of the conflict, as described below
            in the 'conflict-information' subtree (<a href="#tree" class="xref">Section 5.1</a>),
     with only the relevant nodes listed:<a href="#section-4.4.1.3-9" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-10">
              <dt id="section-4.4.1.3-10.1">conflict-information:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.3-10.2">
                <p id="section-4.4.1.3-10.2.1">Indicates that a
                mitigation request is conflicting with another mitigation
                request. This attribute has the following structure:<a href="#section-4.4.1.3-10.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-10.2.2">
                  <dt id="section-4.4.1.3-10.2.2.1">conflict-cause:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-10.2.2.2">
                    <p id="section-4.4.1.3-10.2.2.2.1">Indicates the cause of the
                    conflict. The following value <span class="bcp14">MUST</span> be returned:<a href="#section-4.4.1.3-10.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-10.2.2.2.2">
                      <dt id="section-4.4.1.3-10.2.2.2.2.1">1:</dt>
                      <dd style="margin-left: 1.5em" id="section-4.4.1.3-10.2.2.2.2.2">Overlapping targets. 'conflict-scope'
     provides more
                        details about the conflicting target clauses.<a href="#section-4.4.1.3-10.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.4.1.3-10.2.2.3">conflict-scope:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-10.2.2.4">Characterizes the exact
                    conflict scope. It may include a list of IP addresses, a
                    list of prefixes, a list of target protocols, a list of
                    FQDNs, a list of URIs, a list of aliases, or a 'mid'. A
                    list of port numbers may also be included if there is a
                    common IP address, IP prefix, FQDN, URI, or alias.<a href="#section-4.4.1.3-10.2.2.4" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
<p id="section-4.4.1.3-11">If the DOTS server receives a mitigation request that overlaps
            with an active mitigation request, but both have distinct
            'trigger- mitigation' types, the DOTS server <span class="bcp14">SHOULD</span> deactivate
            (absent explicit policy/configuration otherwise) the mitigation
            request with 'trigger- mitigation' set to 'false'. Particularly,
            if the mitigation request with 'trigger-mitigation' set to 'false'
            is active, the DOTS server withdraws the mitigation request (i.e.,
            status code is set to '7' as defined in <a href="#table3" class="xref">Table 3</a>)
     and transitions
            the status of the mitigation request to '8'.<a href="#section-4.4.1.3-11" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-12">Upon DOTS signal channel session loss with a peer DOTS client,
            the DOTS server <span class="bcp14">SHOULD</span> withdraw (absent explicit
            policy/configuration otherwise) any active mitigation requests
            that overlap with mitigation requests having 'trigger-mitigation'
            set to 'false' from that DOTS client, as the loss of the session
            implicitly activates these preconfigured mitigation requests, and
            they take precedence. Note that the active-but-terminating period
            is not observed for mitigations withdrawn at the initiative of the
            DOTS server.<a href="#section-4.4.1.3-12" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-13">DOTS clients may adopt various strategies for setting the
            scopes of immediate and preconfigured mitigation requests to avoid
            potential conflicts. For example, a DOTS client may tweak
            preconfigured scopes so that the scope of any overlapping
            immediate mitigation request will be a subset of the preconfigured
            scopes. Also, if an immediate mitigation request overlaps with any
            of the preconfigured scopes, the DOTS client sets the scope of the
            overlapping immediate mitigation request to be a subset of the
            preconfigured scopes, so as to get a broad mitigation when the
            DOTS signal channel collapses and to maximize the chance of
            recovery.<a href="#section-4.4.1.3-13" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-14">If the request conflicts with an existing mitigation request
            from a different DOTS client, the DOTS server may return 2.01
            (Created) or 4.09 (Conflict) to the requesting DOTS client. If the
            DOTS server decides to maintain the new mitigation request, the
            DOTS server returns 2.01 (Created) to the requesting DOTS client.
            If the DOTS server decides to reject the new mitigation request,
            the DOTS server returns 4.09 (Conflict) to the requesting DOTS
            client. For both 2.01 (Created) and 4.09 (Conflict) responses, the
            response <span class="bcp14">MUST</span> include enough information for a DOTS client to
            recognize the source of the conflict as described below:<a href="#section-4.4.1.3-14" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-15">
              <dt id="section-4.4.1.3-15.1">conflict-information:</dt>
              <dd style="margin-left: 1.5em" id="section-4.4.1.3-15.2">
                <p id="section-4.4.1.3-15.2.1">Indicates that a
                mitigation request is conflicting with another mitigation
                request(s) from other DOTS client(s). This attribute has the
                following structure:<a href="#section-4.4.1.3-15.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-15.2.2">
                  <dt id="section-4.4.1.3-15.2.2.1">conflict-status:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-15.2.2.2">
                    <p id="section-4.4.1.3-15.2.2.2.1">Indicates the status of a
                    conflicting mitigation request. The following values are
                    defined:<a href="#section-4.4.1.3-15.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-15.2.2.2.2">
                      <dt id="section-4.4.1.3-15.2.2.2.2.1">1:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.2.2.2">DOTS server has detected conflicting mitigation
                        requests from different DOTS clients. This mitigation
                        request is currently inactive until the conflicts are
                        resolved. Another mitigation request is active.<a href="#section-4.4.1.3-15.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.2.2.3">2:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.2.2.4">DOTS server has detected conflicting mitigation
                        requests from different DOTS clients. This mitigation
                        request is currently active.<a href="#section-4.4.1.3-15.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.2.2.5">3:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.2.2.6">DOTS server has detected conflicting mitigation
                        requests from different DOTS clients. All conflicting
                        mitigation requests are inactive.<a href="#section-4.4.1.3-15.2.2.2.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.3">conflict-cause:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-15.2.2.4">
                    <p id="section-4.4.1.3-15.2.2.4.1">Indicates the cause of the
                    conflict. The following values are defined:<a href="#section-4.4.1.3-15.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.1.3-15.2.2.4.2">
                      <dt id="section-4.4.1.3-15.2.2.4.2.1">1:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.4.2.2">Overlapping targets. 'conflict-scope' provides more
                        details about the conflicting target clauses.<a href="#section-4.4.1.3-15.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.4.2.3">2:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.4.2.4">Conflicts with an existing accept-list. This code
                        is returned when the DDoS mitigation detects source
                        addresses/prefixes in the accept-listed Access Control
 Lists (ACLs) are attacking the target.<a href="#section-4.4.1.3-15.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.4.2.5">3:</dt>
                      <dd style="margin-left: 3.0em" id="section-4.4.1.3-15.2.2.4.2.6">CUID Collision. This code is returned when a DOTS
                        client uses a 'cuid' that is already used by another
                        DOTS client. This code is an indication that the
                        request has been rejected and a new request with a new
                        'cuid' is to be re-sent by the DOTS client (see the
                        example shown in <a href="#newcuid" class="xref">Figure 11</a>). Note
                        that 'conflict-status', 'conflict-scope', and
                        'retry-timer' <span class="bcp14">MUST NOT</span> be returned in the error
                        response.<a href="#section-4.4.1.3-15.2.2.4.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.5">conflict-scope:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-15.2.2.6">Characterizes the exact
                    conflict scope. It may include a list of IP addresses, a
                    list of prefixes, a list of target protocols, a list of
                    FQDNs, a list of URIs, a list of aliases, or references to
                    conflicting ACLs (by an 'acl-name', typically <span>[<a href="#RFC8783" class="xref">RFC8783</a>]</span>). A list of port numbers may also
                    be included if there is a common IP address, IP prefix,
                    FQDN, URI, or alias.<a href="#section-4.4.1.3-15.2.2.6" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.4.1.3-15.2.2.7">retry-timer:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.4.1.3-15.2.2.8">
                    <p id="section-4.4.1.3-15.2.2.8.1">Indicates, in seconds, the time
                    after which the DOTS client may reissue the same request.
                    The DOTS server returns 'retry-timer' only to DOTS
                    client(s) for which a mitigation request is deactivated.
                    Any retransmission of the same mitigation request before
                    the expiry of this timer is likely to be rejected by the
                    DOTS server for the same reasons.<a href="#section-4.4.1.3-15.2.2.8.1" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-15.2.2.8.2">The 'retry-timer' <span class="bcp14">SHOULD</span> be equal to the
                    lifetime of the active mitigation request resulting in the
                    deactivation of the conflicting mitigation request.<a href="#section-4.4.1.3-15.2.2.8.2" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-15.2.2.8.3">If the DOTS server decides to
                    maintain a state for the deactivated mitigation request,
                    the DOTS server updates the lifetime of the deactivated
                    mitigation request to 'retry-timer + 45 seconds' (that is,
                    this mitigation request remains deactivated for the entire
                    duration of 'retry-timer + 45 seconds') so that the DOTS
                    client can refresh the deactivated mitigation request
                    after 'retry-timer' seconds, but before the expiry of the
                    lifetime, and check if the conflict is resolved.<a href="#section-4.4.1.3-15.2.2.8.3" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
<span id="name-example-of-generating-a-new"></span><div id="newcuid">
<figure id="figure-11">
              <div id="section-4.4.1.3-16.1">
<pre class="sourcecode">
  (1) Request with a conflicting 'cuid'

  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=12"

  (2) Message body of the 4.09 (Conflict) response
      from the DOTS server

  {
    "ietf-dots-signal-channel:mitigation-scope": {
       "scope": [
          {
            "conflict-information": {
              "conflict-cause": "cuid-collision"
             }
          }
        ]
     }
  }

  (3) Request with a new 'cuid'

  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=f30d281ce6b64fc5a0b91e"
  Uri-Path: "mid=12"
</pre>
</div>
<figcaption><a href="#figure-11" class="selfRef">Figure 11</a>:
<a href="#name-example-of-generating-a-new" class="selfRef">Example of Generating a New 'cuid'</a>
              </figcaption></figure>
</div>
<p id="section-4.4.1.3-17">As an active attack evolves, DOTS clients can adjust
            the scope of requested mitigation as necessary, by refining the
            scope of resources requiring mitigation. This can be achieved by
            sending a PUT request with a new 'mid' value that will override
            the existing one with overlapping mitigation scopes.<a href="#section-4.4.1.3-17" class="pilcrow">¶</a></p>
<p id="section-4.4.1.3-18">For a mitigation request to
            continue beyond the initial negotiated lifetime, the DOTS client
            has to refresh the current mitigation request by sending a new PUT
            request. This PUT request <span class="bcp14">MUST</span> use the same 'mid' value, and it
            <span class="bcp14">MUST</span> repeat all the other parameters as sent in the original
            mitigation request apart from a possible change to the 'lifetime'
            parameter value. In such a case, the DOTS server <span class="bcp14">MAY</span> update the
            mitigation request by setting the remaining lifetime to the newly
            negotiated lifetime, and a 2.04 (Changed) response is returned to
            indicate a successful update of the mitigation request. If this is
            not the case, the DOTS server <span class="bcp14">MUST</span> reject the request with a 4.00
            (Bad Request).<a href="#section-4.4.1.3-18" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="get">
<section id="section-4.4.2">
          <h4 id="name-retrieve-information-relate">
<a href="#section-4.4.2" class="section-number selfRef">4.4.2. </a><a href="#name-retrieve-information-relate" class="section-name selfRef">Retrieve Information Related to a Mitigation</a>
          </h4>
<p id="section-4.4.2-1">A GET request is used by a DOTS client to retrieve information
          (including status) of DOTS mitigations from a DOTS server.<a href="#section-4.4.2-1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-2">'cuid' is a mandatory Uri-Path parameter for GET requests.<a href="#section-4.4.2-2" class="pilcrow">¶</a></p>
<p id="section-4.4.2-3">Uri-Path parameters with empty values <span class="bcp14">MUST NOT</span> be present in a
          request.<a href="#section-4.4.2-3" class="pilcrow">¶</a></p>
<p id="section-4.4.2-4">The same considerations for manipulating the 'cdid' parameter by
          server-domain DOTS gateways specified in <a href="#post" class="xref">Section 4.4.1</a>
            <span class="bcp14">MUST</span> be followed for GET requests.<a href="#section-4.4.2-4" class="pilcrow">¶</a></p>
<p id="section-4.4.2-5">The 'c' Uri-Query option is used to control selection of
          configuration and non-configuration data nodes. Concretely, the 'c'
          (content) parameter and its permitted values defined in Table 2 of
          <span>[<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span> can be used to retrieve
          non-configuration data (attack mitigation status), configuration
          data, or both. The DOTS server <span class="bcp14">MAY</span> support this optional filtering
          capability. It can safely ignore it if not supported. If the DOTS
          client supports the optional filtering capability, it <span class="bcp14">SHOULD</span> use
          "c=n" query (to get back only the dynamically changing data) or
          "c=c" query (to get back the static configuration values) when the
          DDoS attack is active to limit the size of the response.<a href="#section-4.4.2-5" class="pilcrow">¶</a></p>
<span id="name-permitted-values-of-the-c-p"></span><div id="table2">
<table class="center" id="table-2">
            <caption>
<a href="#table-2" class="selfRef">Table 2</a>:
<a href="#name-permitted-values-of-the-c-p" class="selfRef">Permitted Values of the 'c' Parameter</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Value</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">c</td>
                <td class="text-left" rowspan="1" colspan="1">Return only configuration descendant data nodes</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">n</td>
                <td class="text-left" rowspan="1" colspan="1">Return only non-configuration descendant data nodes</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">a</td>
                <td class="text-left" rowspan="1" colspan="1">Return all descendant data nodes</td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-4.4.2-7">The DOTS client can use block-wise transfer <span>[<a href="#RFC7959" class="xref">RFC7959</a>]</span> to get the list of all its mitigations
          maintained by a DOTS server; it can send a Block2 Option in a GET
          request with NUM = 0 to aid in limiting the size of the response. If
          the representation of all the active mitigation requests associated
          with the DOTS client does not fit within a single datagram, the DOTS
          server <span class="bcp14">MUST</span> use the Block2 Option with NUM = 0 in the GET response.
          The Size2 Option may be conveyed in the response to indicate the
          total size of the resource representation. The DOTS client retrieves
          the rest of the representation by sending additional GET requests
          with Block2 Options containing NUM values greater than zero. The
          DOTS client <span class="bcp14">MUST</span> adhere to the block size preferences indicated by
          the DOTS server in the response. If the DOTS server uses the Block2
          Option in the GET response, and the response is for a dynamically
          changing resource (e.g., "c=n" or "c=a" query), the DOTS server <span class="bcp14">MUST</span>
          include the ETag Option in the response. The DOTS client <span class="bcp14">MUST</span>
          include the same ETag value in subsequent GET requests to retrieve
          the rest of the representation.<a href="#section-4.4.2-7" class="pilcrow">¶</a></p>
<p id="section-4.4.2-8">The following examples illustrate how a DOTS client retrieves
          active mitigation requests from a DOTS server. In particular:<a href="#section-4.4.2-8" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.4.2-9.1">
              <a href="#Figure4" class="xref">Figure 12</a> shows the example of a GET
              request to retrieve all DOTS mitigation requests signaled by a
              DOTS client.<a href="#section-4.4.2-9.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.4.2-9.2">
              <a href="#Figure4a" class="xref">Figure 13</a> shows the example of a GET
              request to retrieve a specific DOTS mitigation request signaled
              by a DOTS client. The configuration data to be reported in the
              response is formatted in the same order as it was processed by
              the DOTS server in the original mitigation request.<a href="#section-4.4.2-9.2" class="pilcrow">¶</a>
</li>
          </ul>
<p id="section-4.4.2-10">These two examples assume the default of "c=a"; that is, the DOTS
          client asks for all data to be reported by the DOTS server.<a href="#section-4.4.2-10" class="pilcrow">¶</a></p>
<span id="name-get-to-retrieve-all-dots-mi"></span><div id="Figure4">
<figure id="figure-12">
            <div id="section-4.4.2-11.1">
<pre class="sourcecode">
  Header: GET (Code=0.01)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Observe: 0
</pre>
</div>
<figcaption><a href="#figure-12" class="selfRef">Figure 12</a>:
<a href="#name-get-to-retrieve-all-dots-mi" class="selfRef">GET to Retrieve All DOTS Mitigation Requests</a>
            </figcaption></figure>
</div>
<span id="name-get-to-retrieve-a-specific-"></span><div id="Figure4a">
<figure id="figure-13">
            <div id="section-4.4.2-12.1">
<pre class="sourcecode">
  Header: GET (Code=0.01)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=12332"
  Observe: 0
</pre>
</div>
<figcaption><a href="#figure-13" class="selfRef">Figure 13</a>:
<a href="#name-get-to-retrieve-a-specific-" class="selfRef">GET to Retrieve a Specific DOTS Mitigation Request</a>
            </figcaption></figure>
</div>
<p id="section-4.4.2-13">If the DOTS server does not find the 'mid' Uri-Path value
          conveyed in the GET request in its configuration data for the
          requesting DOTS client, it <span class="bcp14">MUST</span> respond with a 4.04 (Not Found)
          error Response Code. Likewise, the same error <span class="bcp14">MUST</span> be returned as a
          response to a request to retrieve all mitigation records (i.e.,
          'mid' Uri-Path is not defined) of a given DOTS client if the DOTS
          server does not find any mitigation record for that DOTS client. As
          a reminder, a DOTS client is identified by its identity (e.g.,
          client certificate, 'cuid') and optionally the 'cdid'.<a href="#section-4.4.2-13" class="pilcrow">¶</a></p>
<p id="section-4.4.2-14"><a href="#Figure5" class="xref">Figure 14</a> shows a response example of all
          active mitigation requests associated with the DOTS client, as
          maintained by the DOTS server. The response indicates the mitigation
          status of each mitigation request.<a href="#section-4.4.2-14" class="pilcrow">¶</a></p>
<span id="name-response-body-to-a-get-requ"></span><div id="Figure5">
<figure id="figure-14">
            <div id="section-4.4.2-15.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:mitigation-scope": {
    "scope": [
      {
        "mid": 12332,
        "mitigation-start": "1507818434",
        "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
        ],
        "target-protocol": [
          17
        ],
        "lifetime": 1756,
        "status": "attack-successfully-mitigated",
        "bytes-dropped": "134334555",
        "bps-dropped": "43344",
        "pkts-dropped": "333334444",
        "pps-dropped": "432432"
      },
      {
        "mid": 12333,
        "mitigation-start": "1507818393",
        "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
        ],
        "target-protocol": [
          6
        ],
        "lifetime": 1755,
        "status": "attack-stopped",
        "bytes-dropped": "0",
        "bps-dropped": "0",
        "pkts-dropped": "0",
        "pps-dropped": "0"
      }
    ]
  }
}
</pre>
</div>
<figcaption><a href="#figure-14" class="selfRef">Figure 14</a>:
<a href="#name-response-body-to-a-get-requ" class="selfRef">Response Body to a GET Request</a>
            </figcaption></figure>
</div>
<p id="section-4.4.2-16">The mitigation status parameters are described below:<a href="#section-4.4.2-16" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.4.2-17">
            <dt id="section-4.4.2-17.1">mitigation-start:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.2">
              <p id="section-4.4.2-17.2.1">Mitigation start time is
              expressed in seconds relative to 1970-01-01T00:00Z in UTC time
              (<span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-3.4.1" class="relref">Section 3.4.1</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>). The CBOR
              encoding is modified so that the leading tag 1 (epoch-based
              date/time) <span class="bcp14">MUST</span> be omitted.<a href="#section-4.4.2-17.2.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.2.2">This is a
              mandatory attribute when an attack mitigation is active.
              Particularly, 'mitigation-start' is not returned for a
              mitigation with 'status' code set to 8.<a href="#section-4.4.2-17.2.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.3">lifetime:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.4">
              <p id="section-4.4.2-17.4.1">The remaining lifetime of the mitigation
              request, in seconds.<a href="#section-4.4.2-17.4.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.4.2">This is a mandatory
              attribute.<a href="#section-4.4.2-17.4.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.5">status:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.6">
              <p id="section-4.4.2-17.6.1">Status of attack mitigation. The various
              possible values of 'status' parameter are explained in <a href="#table3" class="xref">Table 3</a>.<a href="#section-4.4.2-17.6.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.6.2">This is a mandatory attribute.<a href="#section-4.4.2-17.6.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.7">bytes-dropped:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.8">
              <p id="section-4.4.2-17.8.1">The total dropped byte count for
              the mitigation request since the attack mitigation was
              triggered. The count wraps around when it reaches the maximum
              value of unsigned integer64.<a href="#section-4.4.2-17.8.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.8.2">This is an
              optional attribute.<a href="#section-4.4.2-17.8.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.9">bps-dropped:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.10">
              <p id="section-4.4.2-17.10.1">The average number of dropped bytes
              per second for the mitigation request since the attack
              mitigation was triggered. This average <span class="bcp14">SHOULD</span> be over
              five-minute intervals (that is, measuring bytes into five-minute
              buckets and then averaging these buckets over the time since the
              mitigation was triggered).<a href="#section-4.4.2-17.10.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.10.2">This is an
              optional attribute.<a href="#section-4.4.2-17.10.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.11">pkts-dropped:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.12">
              <p id="section-4.4.2-17.12.1">The total number of dropped packet
              count for the mitigation request since the attack mitigation was
              triggered. The count wraps around when it reaches the maximum
              value of unsigned integer64.<a href="#section-4.4.2-17.12.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.12.2">This is an
              optional attribute.<a href="#section-4.4.2-17.12.2" class="pilcrow">¶</a></p>
</dd>
            <dd class="break"></dd>
<dt id="section-4.4.2-17.13">pps-dropped:</dt>
            <dd style="margin-left: 1.5em" id="section-4.4.2-17.14">
              <p id="section-4.4.2-17.14.1">The average number of dropped packets
              per second for the mitigation request since the attack
              mitigation was triggered. This average <span class="bcp14">SHOULD</span> be over
              five-minute intervals (that is, measuring packets into
              five-minute buckets and then averaging these buckets over the
              time since the mitigation was triggered).<a href="#section-4.4.2-17.14.1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-17.14.2">This is an optional attribute.<a href="#section-4.4.2-17.14.2" class="pilcrow">¶</a></p>
</dd>
          <dd class="break"></dd>
</dl>
<span id="name-values-of-status-parameter"></span><div id="table3">
<table class="center" id="table-3">
            <caption>
<a href="#table-3" class="selfRef">Table 3</a>:
<a href="#name-values-of-status-parameter" class="selfRef">Values of 'status' Parameter</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Parameter Value</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation setup is in progress (e.g.,      
         changing the network path to redirect the inbound  
          traffic to a DOTS mitigator).</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">Attack is being successfully mitigated (e.g.,      
          traffic is redirected to a DDoS mitigator and      
          attack traffic is dropped).</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">3</td>
                <td class="text-left" rowspan="1" colspan="1">Attack has stopped and the DOTS client can         
          withdraw the mitigation request.  This status code 
          will be transmitted for immediate mitigation       
          requests till the mitigation is withdrawn or the   
          lifetime expires.  For mitigation requests with    
          preconfigured scopes (i.e., 'trigger-mitigation'   
          set to 'false'), this status code will be          
          transmitted four times and then transition to '8'.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">4</td>
                <td class="text-left" rowspan="1" colspan="1">Attack has exceeded the mitigation provider        
          capability.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">5</td>
                <td class="text-left" rowspan="1" colspan="1">DOTS client has withdrawn the mitigation request   
          and the mitigation is active but terminating.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">6</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation is now terminated.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">7</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation is withdrawn (by the DOTS        
          server).  If a mitigation request with 'trigger-   
          mitigation' set to 'false' is withdrawn because it 
          overlaps with an immediate mitigation request,     
          this status code will be transmitted four times   
          and then transition to '8' for the mitigation      
          request with preconfigured scopes.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">8</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation will be triggered for the        
          mitigation request only when the DOTS signal       
          channel session is lost.</td>
              </tr>
            </tbody>
          </table>
</div>
<div id="obs">
<section id="section-4.4.2.1">
            <h5 id="name-dots-servers-sending-mitiga">
<a href="#section-4.4.2.1" class="section-number selfRef">4.4.2.1. </a><a href="#name-dots-servers-sending-mitiga" class="section-name selfRef">DOTS Servers Sending Mitigation Status</a>
            </h5>
<p id="section-4.4.2.1-1">The Observe Option defined in <span>[<a href="#RFC7641" class="xref">RFC7641</a>]</span>
            extends the CoAP core protocol with a mechanism for a CoAP client
            to "observe" a resource on a CoAP server: the client retrieves a
            representation of the resource and requests this representation be
            updated by the server as long as the client is interested in the
            resource. DOTS implementations <span class="bcp14">MUST</span> support the Observe Option for
            both 'mitigate' and 'config' (<a href="#uri-path" class="xref">Section 4.2</a>).<a href="#section-4.4.2.1-1" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-2">A DOTS client conveys the Observe Option set to '0' in the GET
            request to receive asynchronous notifications of attack mitigation
            status from the DOTS server.<a href="#section-4.4.2.1-2" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-3">Unidirectional mitigation notifications within the
            bidirectional signal channel enables asynchronous notifications
            between the agents. <span>[<a href="#RFC7641" class="xref">RFC7641</a>]</span> indicates that
            (1) a notification can be sent in a Confirmable or a
            Non-confirmable message and (2) the message type used is
            typically application dependent and may be determined by the
            server for each notification individually. For the DOTS server
            application, the message type <span class="bcp14">MUST</span> always be set to
            Non-confirmable even if the underlying CoAP library elects a
            notification to be sent in a Confirmable message. This overrides
            the behavior defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7641#section-4.5" class="relref">Section 4.5</a> of [<a href="#RFC7641" class="xref">RFC7641</a>]</span> 
     to send a Confirmable message instead of
            a Non-confirmable message at least every 24 hours for the
            following reasons: First, the DOTS signal channel uses a heartbeat
            mechanism to determine if the DOTS client is alive. Second,
            Confirmable messages are not suitable during an attack.<a href="#section-4.4.2.1-3" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-4">Due to the higher likelihood of packet loss during a DDoS
            attack, the DOTS server periodically sends attack mitigation
            status to the DOTS client and also notifies the DOTS client
            whenever the status of the attack mitigation changes. If the DOTS
            server cannot maintain an RTT estimate, it <span class="bcp14">MUST NOT</span> send more than
            one asynchronous notification every 3 seconds and <span class="bcp14">SHOULD</span> use an
            even less aggressive rate whenever possible (case 2 in
            <span><a href="https://www.rfc-editor.org/rfc/rfc8085#section-3.1.3" class="relref">Section 3.1.3</a> of [<a href="#RFC8085" class="xref">RFC8085</a>]</span>).<a href="#section-4.4.2.1-4" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-5">When conflicting requests are detected, the DOTS server
            enforces the corresponding policy (e.g., accept all requests,
            reject all requests, accept only one request but reject all the
            others). It is assumed that this policy is supplied by the DOTS
            server administrator or that it is a default behavior of the DOTS
            server implementation. Then, the DOTS server sends a notification
            message(s) to the DOTS client(s) at the origin of the conflict
            (refer to the conflict parameters defined in <a href="#post" class="xref">Section 4.4.1</a>). A conflict notification message includes
            information about the conflict cause, scope, and the status of the
            mitigation request(s). For example:<a href="#section-4.4.2.1-5" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.4.2.1-6.1">A notification message with 'status' code set to '7 (Attack
                mitigation is withdrawn)' and 'conflict-status' set to '1' is
                sent to a DOTS client to indicate that an active mitigation
                request is deactivated because a conflict is detected.<a href="#section-4.4.2.1-6.1" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-4.4.2.1-6.2">A notification message with 'status' code set to '1 (Attack
                mitigation is in progress)' and 'conflict-status' set to '2'
                is sent to a DOTS client to indicate that this mitigation
                request is in progress, but a conflict is detected.<a href="#section-4.4.2.1-6.2" class="pilcrow">¶</a>
</li>
            </ul>
<p id="section-4.4.2.1-7">Upon receipt of a conflict notification message indicating that
            a mitigation request is deactivated because of a conflict, a DOTS
            client <span class="bcp14">MUST NOT</span> resend the same mitigation request before the
            expiry of 'retry-timer'. It is also recommended that DOTS clients
            support the means to alert administrators about mitigation
            conflicts.<a href="#section-4.4.2.1-7" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-8">A DOTS client that is no longer interested in receiving
            notifications from the DOTS server can simply "forget" the
            observation. When the DOTS server sends the next notification, the
            DOTS client will not recognize the token in the message and, thus,
            will return a Reset message. This causes the DOTS server to remove
            the associated entry. Alternatively, the DOTS client can
            explicitly de-register itself by issuing a GET request that has
            the Token field set to the token of the observation to be canceled
            and includes an Observe Option with the value set to '1'
            (de-register). The latter is more deterministic and, thus, is
            <span class="bcp14">RECOMMENDED</span>.<a href="#section-4.4.2.1-8" class="pilcrow">¶</a></p>
<p id="section-4.4.2.1-9"><a href="#Figure6" class="xref">Figure 15</a> shows an example of a DOTS
            client requesting a DOTS server to send notifications related to a
            mitigation request. Note that for mitigations with preconfigured
            scopes (i.e., 'trigger-mitigation' set to 'false'), the state will
            need to transition from '3' (attack-stopped) to '8'
            (attack-mitigation-signal-loss).<a href="#section-4.4.2.1-9" class="pilcrow">¶</a></p>
<span id="name-notifications-of-attack-mit"></span><div id="Figure6">
<figure id="figure-15">
              <div class="artwork art-text alignCenter" id="section-4.4.2.1-10.1">
<pre>
+-----------+                              +-----------+
|DOTS Client|                              |DOTS Server|
+-----------+                              +-----------+
      |                                          |
      |  GET /&lt;mid&gt;                              |
      |  Token: 0x4a                             | Registration
      |  Observe: 0                              |
      +-----------------------------------------&gt;|
      |                                          |
      |  2.05 Content                            |
      |  Token: 0x4a                             | Notification of
      |  Observe: 12                             | the current state
      |  status: "attack-mitigation-in-progress" |
      |&lt;-----------------------------------------+
      |                                          |
      |  2.05 Content                            |
      |  Token: 0x4a                             | Notification upon
      |  Observe: 44                             | a state change
      |  status: "attack-successfully-mitigated" |
      |&lt;-----------------------------------------+
      |                                          |
      |  2.05 Content                            |
      |  Token: 0x4a                             | Notification upon
      |  Observe: 60                             | a state change
      |  status: "attack-stopped"                |
      |&lt;-----------------------------------------+
      |                                          |
                         ...
</pre>
</div>
<figcaption><a href="#figure-15" class="selfRef">Figure 15</a>:
<a href="#name-notifications-of-attack-mit" class="selfRef">Notifications of Attack Mitigation Status</a>
              </figcaption></figure>
</div>
</section>
</div>
<section id="section-4.4.2.2">
            <h5 id="name-dots-clients-polling-for-mi">
<a href="#section-4.4.2.2" class="section-number selfRef">4.4.2.2. </a><a href="#name-dots-clients-polling-for-mi" class="section-name selfRef">DOTS Clients Polling for Mitigation Status</a>
            </h5>
<p id="section-4.4.2.2-1">The DOTS client can send the GET request at frequent intervals
            without the Observe Option to retrieve the configuration data of
            the mitigation request and non-configuration data (i.e., the
            attack status). DOTS clients <span class="bcp14">MAY</span> be configured with a policy
            indicating the frequency of polling DOTS servers to get the
            mitigation status. This frequency <span class="bcp14">MUST NOT</span> be more than one UDP
            datagram per RTT, as discussed in <span><a href="https://www.rfc-editor.org/rfc/rfc8085#section-3.1.3" class="relref">Section 3.1.3</a> of [<a href="#RFC8085" class="xref">RFC8085</a>]</span>.<a href="#section-4.4.2.2-1" class="pilcrow">¶</a></p>
<p id="section-4.4.2.2-2">If the DOTS server has been able to mitigate the attack and the
            attack has stopped, the DOTS server indicates as such in the
            status. In such case, the DOTS client withdraws the mitigation
            request by issuing a DELETE request for this mitigation request
            (<a href="#del" class="xref">Section 4.4.4</a>).<a href="#section-4.4.2.2-2" class="pilcrow">¶</a></p>
<p id="section-4.4.2.2-3">A DOTS client <span class="bcp14">SHOULD</span> react to the status of the attack per the
            information sent by the DOTS server rather than performing its own
            detection that the attack has been mitigated. This ensures that
            the DOTS client does not withdraw a mitigation request prematurely
            because it is possible that the DOTS client does not sense the
            DDoS attack on its resources, but the DOTS server could be
            actively mitigating the attack because the attack is not
            completely averted.<a href="#section-4.4.2.2-3" class="pilcrow">¶</a></p>
</section>
</section>
</div>
<div id="put">
<section id="section-4.4.3">
          <h4 id="name-efficacy-update-from-dots-c">
<a href="#section-4.4.3" class="section-number selfRef">4.4.3. </a><a href="#name-efficacy-update-from-dots-c" class="section-name selfRef">Efficacy Update from DOTS Clients</a>
          </h4>
<p id="section-4.4.3-1">While DDoS mitigation is in progress, due to the likelihood of
          packet loss, a DOTS client <span class="bcp14">MAY</span> periodically transmit DOTS mitigation
          efficacy updates to the relevant DOTS server. A PUT request is used
          to convey the mitigation efficacy update to the DOTS server. This
          PUT request is treated as a refresh of the current mitigation.<a href="#section-4.4.3-1" class="pilcrow">¶</a></p>
<p id="section-4.4.3-2">The 'attack-status' parameter is a mandatory attribute when
          performing an efficacy update. The various possible values contained
          in the 'attack-status' parameter are described in 
   <a href="#table4" class="xref">Table 4</a>.<a href="#section-4.4.3-2" class="pilcrow">¶</a></p>
<span id="name-values-of-attack-status-par"></span><div id="table4">
<table class="center" id="table-4">
            <caption>
<a href="#table-4" class="selfRef">Table 4</a>:
<a href="#name-values-of-attack-status-par" class="selfRef">Values of 'attack-status' Parameter</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Parameter Value</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">The DOTS client determines that it  
          is still under attack.</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">The DOTS client determines that the 
            attack is successfully mitigated    
           (e.g., attack traffic is not seen).</td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-4.4.3-4">The PUT request used for the efficacy update <span class="bcp14">MUST</span> include all the
          parameters used in the PUT request to carry the DOTS mitigation
          request (<a href="#post" class="xref">Section 4.4.1</a>) unchanged apart from the
          'lifetime' parameter value. If this is not the case, the DOTS server
          <span class="bcp14">MUST</span> reject the request with a 4.00 (Bad Request).<a href="#section-4.4.3-4" class="pilcrow">¶</a></p>
<p id="section-4.4.3-5">The If-Match Option (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.10.8.1" class="relref">Section 5.10.8.1</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>) with an empty value is used to make the
          PUT request conditional on the current existence of the mitigation
          request. If UDP is used as transport, CoAP requests may arrive out
          of order. For example, the DOTS client may send a PUT request to
          convey an efficacy update to the DOTS server followed by a DELETE
          request to withdraw the mitigation request, but the DELETE request
          arrives at the DOTS server before the PUT request. To handle
          out-of-order delivery of requests, if an If-Match Option is present
          in the PUT request and the 'mid' in the request matches a mitigation
          request from that DOTS client, the request is processed by the DOTS
          server. If no match is found, the PUT request is silently ignored by
          the DOTS server.<a href="#section-4.4.3-5" class="pilcrow">¶</a></p>
<p id="section-4.4.3-6">An example of an efficacy update message, which includes an
          If-Match Option with an empty value, is depicted in <a href="#Figure7" class="xref">Figure 16</a>.<a href="#section-4.4.3-6" class="pilcrow">¶</a></p>
<span id="name-an-example-of-efficacy-upda"></span><div id="Figure7">
<figure id="figure-16">
            <div id="section-4.4.3-7.1">
<pre class="sourcecode">
   Header: PUT (Code=0.03)
   Uri-Path: ".well-known"
   Uri-Path: "dots"
   Uri-Path: "mitigate"
   Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
   Uri-Path: "mid=123"
   If-Match:
   Content-Format: "application/dots+cbor"

   {
    "ietf-dots-signal-channel:mitigation-scope": {
      "scope": [
        {
          "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
           ],
          "target-port-range": [
            {
              "lower-port": 80
            },
            {
              "lower-port": 443
            },
            {
               "lower-port": 8080
            }
          ],
          "target-protocol": [
             6
          ],
          "attack-status": "under-attack"
        }
      ]
    }
   }
</pre>
</div>
<figcaption><a href="#figure-16" class="selfRef">Figure 16</a>:
<a href="#name-an-example-of-efficacy-upda" class="selfRef">An Example of Efficacy Update</a>
            </figcaption></figure>
</div>
<p id="section-4.4.3-8">The DOTS server indicates the result of processing a PUT request
          using CoAP Response Codes. The Response Code 2.04 (Changed) is
          returned if the DOTS server has accepted the mitigation efficacy
          update. The error Response Code 5.03 (Service Unavailable) is
          returned if the DOTS server has erred or is incapable of performing
          the mitigation. As specified in <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>, 5.03
          uses Max-Age Option to indicate the number of seconds after which to
          retry.<a href="#section-4.4.3-8" class="pilcrow">¶</a></p>
</section>
</div>
<div id="del">
<section id="section-4.4.4">
          <h4 id="name-withdraw-a-mitigation">
<a href="#section-4.4.4" class="section-number selfRef">4.4.4. </a><a href="#name-withdraw-a-mitigation" class="section-name selfRef">Withdraw a Mitigation</a>
          </h4>
<p id="section-4.4.4-1">DELETE requests are used to withdraw DOTS mitigation requests
          from DOTS servers (<a href="#Figure3" class="xref">Figure 17</a>).<a href="#section-4.4.4-1" class="pilcrow">¶</a></p>
<p id="section-4.4.4-2">'cuid' and 'mid' are mandatory Uri-Path parameters for DELETE
          requests.<a href="#section-4.4.4-2" class="pilcrow">¶</a></p>
<p id="section-4.4.4-3">The same considerations for manipulating the 'cdid' parameter by DOTS
          gateways, as specified in <a href="#post" class="xref">Section 4.4.1</a>, <span class="bcp14">MUST</span> be
          followed for DELETE requests. Uri-Path parameters with empty values
          <span class="bcp14">MUST NOT</span> be present in a request.<a href="#section-4.4.4-3" class="pilcrow">¶</a></p>
<span id="name-withdraw-a-dots-mitigation"></span><div id="Figure3">
<figure id="figure-17">
            <div id="section-4.4.4-4.1">
<pre class="sourcecode">
  Header: DELETE (Code=0.04)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "mitigate"
  Uri-Path: "cuid=dz6pHjaADkaFTbjr0JGBpw"
  Uri-Path: "mid=123"
</pre>
</div>
<figcaption><a href="#figure-17" class="selfRef">Figure 17</a>:
<a href="#name-withdraw-a-dots-mitigation" class="selfRef">Withdraw a DOTS Mitigation</a>
            </figcaption></figure>
</div>
<p id="section-4.4.4-5">If the DELETE request does not include 'cuid' and 'mid'
          parameters, the DOTS server <span class="bcp14">MUST</span> reply with a 4.00 (Bad
          Request).<a href="#section-4.4.4-5" class="pilcrow">¶</a></p>
<p id="section-4.4.4-6">Once the request is validated, the DOTS server immediately
          acknowledges a DOTS client's request to withdraw the DOTS mitigation
          request using a 2.02 (Deleted) Response Code with no response payload.
          A 2.02 (Deleted) Response Code is returned even if the 'mid'
          parameter value conveyed in the DELETE request does not exist in its
          configuration data before the request.<a href="#section-4.4.4-6" class="pilcrow">¶</a></p>
<p id="section-4.4.4-7">If the DOTS server finds the 'mid' parameter value conveyed in
          the DELETE request in its configuration data for the DOTS client,
          then to protect against route or DNS flapping caused by a DOTS
          client rapidly removing a mitigation and to dampen the effect of
          oscillating attacks, the DOTS server <span class="bcp14">MAY</span> allow mitigation to
          continue for a limited period after acknowledging a DOTS client's
          withdrawal of a mitigation request. During this period, the DOTS
          server status messages <span class="bcp14">SHOULD</span> indicate that mitigation is active but
          terminating (<a href="#get" class="xref">Section 4.4.2</a>).<a href="#section-4.4.4-7" class="pilcrow">¶</a></p>
<p id="section-4.4.4-8">The initial active-but-terminating period <span class="bcp14">SHOULD</span> be sufficiently
          long to absorb latency incurred by route propagation. The
          active-but-terminating period <span class="bcp14">SHOULD</span> be set by default to 120
          seconds. If the client requests mitigation again before the initial
          active-but-terminating period elapses, the DOTS server <span class="bcp14">MAY</span>
          exponentially increase (the base of the exponent is 2) the
          active-but-terminating period up to a maximum of 300 seconds (5
          minutes).<a href="#section-4.4.4-8" class="pilcrow">¶</a></p>
<p id="section-4.4.4-9">Once the active-but-terminating period elapses, the DOTS server
          <span class="bcp14">MUST</span> treat the mitigation as terminated.<a href="#section-4.4.4-9" class="pilcrow">¶</a></p>
<p id="section-4.4.4-10">If a mitigation is triggered due to a signal channel loss, the
          DOTS server relies upon normal triggers to stop that mitigation
          (typically, receipt of a valid DELETE request, expiry of the
          mitigation lifetime, or scrubbing the traffic to the attack target).
          In particular, the DOTS server <span class="bcp14">MUST NOT</span> consider the signal channel
          recovery as a trigger to stop the mitigation.<a href="#section-4.4.4-10" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="sigconfig">
<section id="section-4.5">
        <h3 id="name-dots-signal-channel-session">
<a href="#section-4.5" class="section-number selfRef">4.5. </a><a href="#name-dots-signal-channel-session" class="section-name selfRef">DOTS Signal Channel Session Configuration</a>
        </h3>
<p id="section-4.5-1">A DOTS client can negotiate, configure, and retrieve the DOTS
        signal channel session behavior with its DOTS peers. The DOTS signal
        channel can be used, for example, to configure the following:<a href="#section-4.5-1" class="pilcrow">¶</a></p>
<ol start="1" type="a" class="normal type-a" id="section-4.5-2">
   <li id="section-4.5-2.1">Heartbeat interval ('heartbeat-interval'): DOTS agents
            regularly send heartbeats to each other after mutual
            authentication is successfully completed in order to keep the DOTS
            signal channel open. Heartbeat messages are exchanged between DOTS
            agents every 'heartbeat-interval' seconds to detect the current
            status of the DOTS signal channel session.<a href="#section-4.5-2.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.5-2.2">Missing heartbeats allowed ('missing-hb-allowed'): This
            variable indicates the maximum number of consecutive heartbeat
            messages for which a DOTS agent did not receive a response before
            concluding that the session is disconnected or defunct.<a href="#section-4.5-2.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.5-2.3">Acceptable probing rate ('probing-rate'): This parameter
            indicates the average data rate that must not be exceeded by a
            DOTS agent in sending to a peer DOTS agent that does not
            respond.<a href="#section-4.5-2.3" class="pilcrow">¶</a>
</li>
          <li id="section-4.5-2.4">Acceptable signal loss ratio: Maximum retransmissions
            ('max-retransmit'), retransmission timeout value ('ack-timeout'),
            and other message transmission parameters for Confirmable messages
            over the DOTS signal channel.<a href="#section-4.5-2.4" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.5-3">When the DOTS signal channel is established over a reliable
        transport (e.g., TCP), there is no need for the reliability mechanisms
        provided by CoAP over UDP since the underlying TCP connection provides
        retransmissions and deduplication <span>[<a href="#RFC8323" class="xref">RFC8323</a>]</span>. CoAP
        over reliable transports does not support Confirmable or
        Non-confirmable message types. As such, the transmission-related
        parameters ('missing-hb-allowed' and acceptable signal loss ratio) are
        negotiated only for DOTS over unreliable transports.<a href="#section-4.5-3" class="pilcrow">¶</a></p>
<p id="section-4.5-4">The same or distinct configuration sets may be used during times
        when a mitigation is active ('mitigating-config') and when no
        mitigation is active ('idle-config'). This is particularly useful for
        DOTS servers that might want to reduce heartbeat frequency or cease
        heartbeat exchanges when an active DOTS client has not requested
        mitigation. If distinct configurations are used, DOTS agents <span class="bcp14">MUST</span>
        follow the appropriate configuration set as a function of the
        mitigation activity (e.g., if no mitigation request is active (also
        referred to as 'idle' time), values related to 'idle-config' must be
        followed). Additionally, DOTS agents <span class="bcp14">MUST</span> automatically switch to the
        other configuration upon a change in the mitigation activity (e.g., if
        an attack mitigation is launched after an 'idle' time, the DOTS agent
        switches from values related to 'idle-config' to values related to
        'mitigating-config').<a href="#section-4.5-4" class="pilcrow">¶</a></p>
<p id="section-4.5-5">CoAP requests and responses are indicated for reliable delivery by
        marking them as Confirmable messages. DOTS signal channel session
        configuration requests and responses are marked as Confirmable
        messages. As explained in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-2.1" class="relref">Section 2.1</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>, 
 a Confirmable message is retransmitted using
        a default timeout and exponential backoff between retransmissions
        until the DOTS server sends an Acknowledgement message (ACK) with the
        same Message ID conveyed from the DOTS client.<a href="#section-4.5-5" class="pilcrow">¶</a></p>
<p id="section-4.5-6">Message transmission parameters are defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.8" class="relref">Section 4.8</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>. The DOTS server can either piggyback the
        response in the Acknowledgement message or, if the DOTS server cannot
        respond immediately to a request carried in a Confirmable message, it
        simply responds with an Empty Acknowledgement message so that the DOTS
        client can stop retransmitting the request. Empty Acknowledgement
        messages are explained in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-2.2" class="relref">Section 2.2</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>. When the response is ready, the server sends
        it in a new Confirmable message, which, in turn, needs to be
        acknowledged by the DOTS client (see Sections <a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.2.1" class="relref">5.2.1</a> and <a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.2.2" class="relref">5.2.2</a>
 of <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>). Requests and responses exchanged between
        DOTS agents during 'idle' time, except heartbeat messages, are marked
        as Confirmable messages.<a href="#section-4.5-6" class="pilcrow">¶</a></p>
<aside id="section-4.5-7">
          <p id="section-4.5-7.1">Implementation Note: A DOTS client that receives a response in
        a Confirmable message may want to clean up the message state
        right after sending the ACK.  If that ACK is lost and the DOTS
        server retransmits the Confirmable message, the DOTS client may
        no longer have any state that would help it correlate this
        response; from the DOTS client's standpoint, the retransmission
        message is unexpected.  The DOTS client will send a Reset
        message so it does not receive any more retransmissions.  This
        behavior is normal and not an indication of an error (see
        <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.3.2" class="relref">Section 5.3.2</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span> for more details).<a href="#section-4.5-7.1" class="pilcrow">¶</a></p>
</aside>
<div id="discovery">
<section id="section-4.5.1">
          <h4 id="name-discover-configuration-para">
<a href="#section-4.5.1" class="section-number selfRef">4.5.1. </a><a href="#name-discover-configuration-para" class="section-name selfRef">Discover Configuration Parameters</a>
          </h4>
<p id="section-4.5.1-1">A GET request is used to obtain acceptable (e.g., minimum and
          maximum values) and current configuration parameters on the DOTS
          server for DOTS signal channel session configuration. This procedure
          occurs between a DOTS client and its immediate peer DOTS server. As
          such, this GET request <span class="bcp14">MUST NOT</span> be relayed by a DOTS gateway.<a href="#section-4.5.1-1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-2"><a href="#Figure18" class="xref">Figure 18</a> shows how to obtain configuration
          parameters that the DOTS server will find acceptable.<a href="#section-4.5.1-2" class="pilcrow">¶</a></p>
<span id="name-get-to-retrieve-configurati"></span><div id="Figure18">
<figure id="figure-18">
            <div id="section-4.5.1-3.1">
<pre class="sourcecode">
  Header: GET (Code=0.01)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "config"
</pre>
</div>
<figcaption><a href="#figure-18" class="selfRef">Figure 18</a>:
<a href="#name-get-to-retrieve-configurati" class="selfRef">GET to Retrieve Configuration</a>
            </figcaption></figure>
</div>
<p id="section-4.5.1-4">The DOTS server in the 2.05 (Content) response conveys the
          current, minimum, and maximum attribute values acceptable by the
          DOTS server (<a href="#Figure19" class="xref">Figure 19</a>).<a href="#section-4.5.1-4" class="pilcrow">¶</a></p>
<span id="name-get-configuration-response-"></span><div id="Figure19">
<figure id="figure-19">
            <div id="section-4.5.1-5.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:signal-config": {
    "mitigating-config": {
      "heartbeat-interval": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "missing-hb-allowed": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "probing-rate": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "max-retransmit": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "ack-timeout": {
        "max-value-decimal": "string",
        "min-value-decimal": "string",
        "current-value-decimal": "string"
      },
      "ack-random-factor": {
        "max-value-decimal": "string",
        "min-value-decimal": "string",
        "current-value-decimal": "string"
      }
    },
    "idle-config": {
      "heartbeat-interval": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "missing-hb-allowed": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "probing-rate": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "max-retransmit": {
        "max-value": number,
        "min-value": number,
        "current-value": number
      },
      "ack-timeout": {
        "max-value-decimal": "string",
        "min-value-decimal": "string",
        "current-value-decimal": "string"
      },
      "ack-random-factor": {
        "max-value-decimal": "string",
        "min-value-decimal": "string",
        "current-value-decimal": "string"
      }
    }
  }
}
</pre>
</div>
<figcaption><a href="#figure-19" class="selfRef">Figure 19</a>:
<a href="#name-get-configuration-response-" class="selfRef">GET Configuration Response Body Schema</a>
            </figcaption></figure>
</div>
<p id="section-4.5.1-6">The parameters in <a href="#Figure19" class="xref">Figure 19</a> are described
          below:<a href="#section-4.5.1-6" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.5.1-7">
            <dt id="section-4.5.1-7.1">mitigating-config:</dt>
            <dd style="margin-left: 1.5em" id="section-4.5.1-7.2">
              <p id="section-4.5.1-7.2.1">Set of configuration parameters
              to use when a mitigation is active. The following parameters may
              be included:<a href="#section-4.5.1-7.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.5.1-7.2.2">
                <dt id="section-4.5.1-7.2.2.1">heartbeat-interval:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.2">
                  <p id="section-4.5.1-7.2.2.2.1">Time interval in seconds
                  between two consecutive heartbeat messages.<a href="#section-4.5.1-7.2.2.2.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.2.2">'0' is used to disable the heartbeat
                  mechanism.<a href="#section-4.5.1-7.2.2.2.2" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.2.3">This is an optional
                  attribute.<a href="#section-4.5.1-7.2.2.2.3" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
<dt id="section-4.5.1-7.2.2.3">missing-hb-allowed:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.4">
                  <p id="section-4.5.1-7.2.2.4.1">Maximum number of
                  consecutive heartbeat messages for which the DOTS agent did
                  not receive a response before concluding that the session is
                  disconnected.<a href="#section-4.5.1-7.2.2.4.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.4.2">This is an optional
                  attribute.<a href="#section-4.5.1-7.2.2.4.2" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
<dt id="section-4.5.1-7.2.2.5">probing-rate:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.6">
                  <p id="section-4.5.1-7.2.2.6.1">The average data rate, in
                  bytes/second, that must not be exceeded by a DOTS agent in
                  sending to a peer DOTS agent that does not respond (referred
                  to as PROBING_RATE parameter in CoAP).<a href="#section-4.5.1-7.2.2.6.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.6.2">This is an optional attribute.<a href="#section-4.5.1-7.2.2.6.2" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
<dt id="section-4.5.1-7.2.2.7">max-retransmit:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.8">
                  <p id="section-4.5.1-7.2.2.8.1">Maximum number of
                  retransmissions for a message (referred to as MAX_RETRANSMIT
                  parameter in CoAP).<a href="#section-4.5.1-7.2.2.8.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.8.2">This is an
                  optional attribute.<a href="#section-4.5.1-7.2.2.8.2" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
<dt id="section-4.5.1-7.2.2.9">ack-timeout:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.10">
                  <p id="section-4.5.1-7.2.2.10.1">Timeout value in seconds used to
                  calculate the initial retransmission timeout value (referred
                  to as ACK_TIMEOUT parameter in CoAP).<a href="#section-4.5.1-7.2.2.10.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.10.2">This is an optional attribute.<a href="#section-4.5.1-7.2.2.10.2" class="pilcrow">¶</a></p>
</dd>
                <dd class="break"></dd>
<dt id="section-4.5.1-7.2.2.11">ack-random-factor:</dt>
                <dd style="margin-left: 1.5em" id="section-4.5.1-7.2.2.12">
                  <p id="section-4.5.1-7.2.2.12.1">Random factor used to
                  influence the timing of retransmissions (referred to as
                  ACK_RANDOM_FACTOR parameter in CoAP).<a href="#section-4.5.1-7.2.2.12.1" class="pilcrow">¶</a></p>
<p id="section-4.5.1-7.2.2.12.2">This is an optional attribute.<a href="#section-4.5.1-7.2.2.12.2" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
<dt id="section-4.5.1-7.3">idle-config:</dt>
            <dd style="margin-left: 1.5em" id="section-4.5.1-7.4">Set of configuration parameters to
              use when no mitigation is active. This attribute has the same
              structure as 'mitigating-config'.<a href="#section-4.5.1-7.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
</dl>
<p id="section-4.5.1-8"><a href="#Figure17" class="xref">Figure 20</a> shows an example of acceptable
          and current configuration parameters on a DOTS server for DOTS
          signal channel session configuration. The same acceptable
          configuration is used during mitigation and idle times.<a href="#section-4.5.1-8" class="pilcrow">¶</a></p>
<span id="name-example-of-a-configuration-"></span><div id="Figure17">
<figure id="figure-20">
            <div id="section-4.5.1-9.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:signal-config": {
    "mitigating-config": {
      "heartbeat-interval": {
        "max-value": 240,
        "min-value": 15,
        "current-value": 30
      },
      "missing-hb-allowed": {
        "max-value": 20,
        "min-value": 3,
        "current-value": 15
      },
      "probing-rate": {
        "max-value": 20,
        "min-value": 5,
        "current-value": 15
      },
      "max-retransmit": {
        "max-value": 15,
        "min-value": 2,
        "current-value": 3
      },
      "ack-timeout": {
        "max-value-decimal": "30.00",
        "min-value-decimal": "1.00",
        "current-value-decimal": "2.00"
      },
      "ack-random-factor": {
        "max-value-decimal": "4.00",
        "min-value-decimal": "1.10",
        "current-value-decimal": "1.50"
      }
    },
    "idle-config": {
      "heartbeat-interval": {
        "max-value": 240,
        "min-value": 15,
        "current-value": 30
      },
      "missing-hb-allowed": {
        "max-value": 20,
        "min-value": 3,
        "current-value": 15
      },
      "probing-rate": {
        "max-value": 20,
        "min-value": 5,
        "current-value": 15
      },
      "max-retransmit": {
        "max-value": 15,
        "min-value": 2,
        "current-value": 3
      },
      "ack-timeout": {
        "max-value-decimal": "30.00",
        "min-value-decimal": "1.00",
        "current-value-decimal": "2.00"
      },
      "ack-random-factor": {
        "max-value-decimal": "4.00",
        "min-value-decimal": "1.10",
        "current-value-decimal": "1.50"
      }
    }
  }
}
</pre>
</div>
<figcaption><a href="#figure-20" class="selfRef">Figure 20</a>:
<a href="#name-example-of-a-configuration-" class="selfRef">Example of a Configuration Response Body</a>
            </figcaption></figure>
</div>
</section>
</div>
<div id="convey">
<section id="section-4.5.2">
          <h4 id="name-convey-dots-signal-channel-">
<a href="#section-4.5.2" class="section-number selfRef">4.5.2. </a><a href="#name-convey-dots-signal-channel-" class="section-name selfRef">Convey DOTS Signal Channel Session Configuration</a>
          </h4>
<p id="section-4.5.2-1">A PUT request (Figures <a href="#Figure13" class="xref">21</a> and <a href="#Figure13a" class="xref">22</a>) is used to convey the configuration
          parameters for the signal channel (e.g., heartbeat interval, maximum
          retransmissions). Message transmission parameters for CoAP are
          defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.8" class="relref">Section 4.8</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>. The
          <span class="bcp14">RECOMMENDED</span> values of transmission parameter values are
          'ack-timeout' (2 seconds), 'max-retransmit' (3), and
          'ack-random-factor' (1.5). In addition to those parameters, the
          <span class="bcp14">RECOMMENDED</span> specific DOTS transmission parameter values are
          'heartbeat-interval' (30 seconds) and 'missing-hb-allowed' (15).<a href="#section-4.5.2-1" class="pilcrow">¶</a></p>
<aside id="section-4.5.2-2">
            <p id="section-4.5.2-2.1">Note: 'heartbeat-interval' should be tweaked to also assist
        DOTS messages for NAT traversal (SIG-011 of <span>[<a href="#RFC8612" class="xref">RFC8612</a>]</span>).
        According to <span>[<a href="#RFC8085" class="xref">RFC8085</a>]</span>, heartbeat messages must not be
 sent
        more frequently than once every 15 seconds and should use
        longer intervals when possible.  Furthermore, <span>[<a href="#RFC4787" class="xref">RFC4787</a>]</span>
        recommends that NATs use a state timeout of 2 minutes or
        longer, but experience shows that sending packets every 15 to
        30 seconds is necessary to prevent the majority of middleboxes
        from losing state for UDP flows.  From that standpoint, the
        <span class="bcp14">RECOMMENDED</span> minimum 'heartbeat-interval' is 15 seconds and the
        <span class="bcp14">RECOMMENDED</span> maximum 'heartbeat-interval' is 240 seconds.  The
        recommended value of 30 seconds is selected to anticipate the
        expiry of NAT state.<a href="#section-4.5.2-2.1" class="pilcrow">¶</a></p>
<p id="section-4.5.2-2.2">A 'heartbeat-interval' of 30 seconds may be considered to be
        too chatty in some deployments.  For such deployments, DOTS
        agents may negotiate longer 'heartbeat-interval' values to
        prevent any network overload with too frequent heartbeats.<a href="#section-4.5.2-2.2" class="pilcrow">¶</a></p>
<p id="section-4.5.2-2.3">Different heartbeat intervals can be defined for 'mitigating-
        config' and 'idle-config' to reduce being too chatty during
        idle times.  If there is an on-path translator between the DOTS
        client (standalone or part of a DOTS gateway) and the DOTS
        server, the 'mitigating-config' 'heartbeat-interval' has to be
        smaller than the translator session timeout.  It is recommended
        that the 'idle-config' 'heartbeat-interval' also be smaller
        than the translator session timeout to prevent translator
        traversal issues or that it be disabled entirely.  Means to
        discover the lifetime assigned by a translator are out of
        scope.<a href="#section-4.5.2-2.3" class="pilcrow">¶</a></p>
<p id="section-4.5.2-2.4">Given that the size of the heartbeat request cannot exceed
        ('heartbeat-interval' * 'probing-rate') bytes, 'probing-rate'
        should be set appropriately to avoid slowing down heartbeat
        exchanges.  For example, 'probing-rate' may be set to 2 *
        ("size of encrypted DOTS heartbeat request"/'heartbeat-
        interval') or (("size of encrypted DOTS heartbeat request" +
        "average size of an encrypted mitigation request")/'heartbeat-
        interval').  Absent any explicit configuration or inability to
        dynamically adjust 'probing-rate' values (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.8.1" class="relref">Section 4.8.1</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>), DOTS agents use 5 bytes/second as a default
        'probing-rate' value.<a href="#section-4.5.2-2.4" class="pilcrow">¶</a></p>
</aside>
<p id="section-4.5.2-3">If the DOTS agent wishes to change the default values of message
          transmission parameters, it <span class="bcp14">SHOULD</span> follow the guidance given in
          <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-4.8.1" class="relref">Section 4.8.1</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>. 
   The DOTS agents
          <span class="bcp14">MUST</span> use the negotiated values for message transmission parameters
          and default values for non-negotiated message transmission
          parameters.<a href="#section-4.5.2-3" class="pilcrow">¶</a></p>
<p id="section-4.5.2-4">The signal channel session configuration is applicable to a
          single DOTS signal channel session between DOTS agents, so the
          'cuid' Uri-Path <span class="bcp14">MUST NOT</span> be used.<a href="#section-4.5.2-4" class="pilcrow">¶</a></p>
<span id="name-put-to-convey-the-dots-sign"></span><div id="Figure13">
<figure id="figure-21">
            <div id="section-4.5.2-5.1">
<pre class="sourcecode">
  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "config"
  Uri-Path: "sid=123"
  Content-Format: "application/dots+cbor"

  {
   ...
  }
</pre>
</div>
<figcaption><a href="#figure-21" class="selfRef">Figure 21</a>:
<a href="#name-put-to-convey-the-dots-sign" class="selfRef">PUT to Convey the DOTS Signal Channel Session Configuration Data</a>
            </figcaption></figure>
</div>
<p id="section-4.5.2-6">The additional Uri-Path parameter to those defined in 
   <a href="#table1" class="xref">Table 1</a> is as follows:<a href="#section-4.5.2-6" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.5.2-7">
            <dt id="section-4.5.2-7.1">sid:</dt>
            <dd style="margin-left: 3.0em" id="section-4.5.2-7.2">
              <p id="section-4.5.2-7.2.1">Session Identifier is an identifier for the
              DOTS signal channel session configuration data represented as an
              integer. This identifier <span class="bcp14">MUST</span> be generated by DOTS clients.
              'sid' values <span class="bcp14">MUST</span> increase monotonically (when a new PUT is
              generated by a DOTS client to convey the configuration
              parameters for the signal channel).<a href="#section-4.5.2-7.2.1" class="pilcrow">¶</a></p>
<p id="section-4.5.2-7.2.2">This is a mandatory attribute.<a href="#section-4.5.2-7.2.2" class="pilcrow">¶</a></p>
</dd>
          <dd class="break"></dd>
</dl>
<span id="name-put-to-convey-the-dots-signa"></span><div id="Figure13a">
<figure id="figure-22">
            <div id="section-4.5.2-8.1">
<pre class="sourcecode">
  {
    "ietf-dots-signal-channel:signal-config": {
      "mitigating-config": {
        "heartbeat-interval": {
          "current-value": number
        },
        "missing-hb-allowed": {
          "current-value": number
        },
        "probing-rate": {
          "current-value": number
        },
        "max-retransmit": {
          "current-value": number
        },
        "ack-timeout": {
          "current-value-decimal": "string"
        },
        "ack-random-factor": {
          "current-value-decimal": "string"
        }
      },
      "idle-config": {
        "heartbeat-interval": {
          "current-value": number
        },
        "missing-hb-allowed": {
          "current-value": number
        },
        "probing-rate": {
          "current-value": number
        },
        "max-retransmit": {
          "current-value": number
        },
        "ack-timeout": {
          "current-value-decimal": "string"
        },
        "ack-random-factor": {
          "current-value-decimal": "string"
        }
      }
    }
  }
</pre>
</div>
<figcaption><a href="#figure-22" class="selfRef">Figure 22</a>:
<a href="#name-put-to-convey-the-dots-signa" class="selfRef">PUT to Convey the DOTS Signal Channel Session Configuration Data (Message Body Schema)</a>
            </figcaption></figure>
</div>
<p id="section-4.5.2-9">The meaning of the parameters in the CBOR body (<a href="#Figure13a" class="xref">Figure 22</a>) is defined in <a href="#discovery" class="xref">Section 4.5.1</a>.<a href="#section-4.5.2-9" class="pilcrow">¶</a></p>
<p id="section-4.5.2-10">At least one of the attributes 'heartbeat-interval',
          'missing-hb-allowed', 'probing-rate', 'max-retransmit',
          'ack-timeout', and 'ack-random-factor' <span class="bcp14">MUST</span> be present in the PUT
          request. Note that 'heartbeat-interval', 'missing-hb-allowed',
          'probing-rate', 'max-retransmit', 'ack-timeout', and
          'ack-random-factor', if present, do not need to be provided for both
          'mitigating-config' and 'idle-config' in a PUT request. A request
          does not need to include both 'mitigating-config' and 'idle-config'
          attributes.<a href="#section-4.5.2-10" class="pilcrow">¶</a></p>
<p id="section-4.5.2-11">The PUT request with a higher numeric 'sid' value overrides the
          DOTS signal channel session configuration data installed by a PUT
          request with a lower numeric 'sid' value. That is, the configuration
          parameters that are included in the PUT request with a higher
          numeric 'sid' value will be used instead of the DOTS server's
          defaults. To avoid maintaining a long list of 'sid' requests from a
          DOTS client, the lower numeric 'sid' <span class="bcp14">MUST</span> be automatically deleted
          and no longer available at the DOTS server.<a href="#section-4.5.2-11" class="pilcrow">¶</a></p>
<p id="section-4.5.2-12"><a href="#Figure14" class="xref">Figure 23</a> shows a PUT request example to
          convey the configuration parameters for the DOTS signal channel. In
          this example, the heartbeat mechanism is disabled when no mitigation
          is active, while the heartbeat interval is set to '30' when a
          mitigation is active.<a href="#section-4.5.2-12" class="pilcrow">¶</a></p>
<span id="name-put-to-convey-the-configura"></span><div id="Figure14">
<figure id="figure-23">
            <div id="section-4.5.2-13.1">
<pre class="sourcecode">
  Header: PUT (Code=0.03)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "config"
  Uri-Path: "sid=123"
  Content-Format: "application/dots+cbor"

  {
    "ietf-dots-signal-channel:signal-config": {
      "mitigating-config": {
        "heartbeat-interval": {
          "current-value": 30
        },
        "missing-hb-allowed": {
          "current-value": 15
        },
        "probing-rate": {
          "current-value": 15
        },
        "max-retransmit": {
          "current-value": 3
        },
        "ack-timeout": {
          "current-value-decimal": "2.00"
        },
        "ack-random-factor": {
          "current-value-decimal": "1.50"
        }
      },
      "idle-config": {
        "heartbeat-interval": {
          "current-value": 0
        },
        "max-retransmit": {
          "current-value": 3
        },
        "ack-timeout": {
          "current-value-decimal": "2.00"
        },
        "ack-random-factor": {
          "current-value-decimal": "1.50"
        }
      }
    }
  }
</pre>
</div>
<figcaption><a href="#figure-23" class="selfRef">Figure 23</a>:
<a href="#name-put-to-convey-the-configura" class="selfRef">PUT to Convey the Configuration Parameters</a>
            </figcaption></figure>
</div>
<p id="section-4.5.2-14">The DOTS server indicates the result of processing the PUT
          request using CoAP Response Codes:<a href="#section-4.5.2-14" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.5.2-15.1">If the request is missing a mandatory attribute, does not
              include a 'sid' Uri-Path, or contains one or more invalid or
              unknown parameters, 4.00 (Bad Request) <span class="bcp14">MUST</span> be returned in the
              response.<a href="#section-4.5.2-15.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.5.2-15.2">If the DOTS server does not find the 'sid' parameter value
              conveyed in the PUT request in its configuration data and if the
              DOTS server has accepted the configuration parameters, then a
              Response Code 2.01 (Created) <span class="bcp14">MUST</span> be returned in the
              response.<a href="#section-4.5.2-15.2" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.5.2-15.3">If the DOTS server finds the 'sid' parameter value conveyed
              in the PUT request in its configuration data and if the DOTS
              server has accepted the updated configuration parameters, 2.04
              (Changed) <span class="bcp14">MUST</span> be returned in the response.<a href="#section-4.5.2-15.3" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.5.2-15.4">
              <p id="section-4.5.2-15.4.1">If any of the 'heartbeat-interval', 'missing-hb-allowed',
              'probing-rate', 'max-retransmit', 'target-protocol',
              'ack-timeout', and 'ack-random-factor' attribute values are not
              acceptable to the DOTS server, 4.22 (Unprocessable Entity) <span class="bcp14">MUST</span>
              be returned in the response. Upon receipt of this error code,
              the DOTS client <span class="bcp14">SHOULD</span> retrieve the maximum and minimum
              attribute values acceptable to the DOTS server (<a href="#discovery" class="xref">Section 4.5.1</a>).<a href="#section-4.5.2-15.4.1" class="pilcrow">¶</a></p>
<p id="section-4.5.2-15.4.2">The DOTS
              client may retry and send the PUT request with updated attribute
              values acceptable to the DOTS server.<a href="#section-4.5.2-15.4.2" class="pilcrow">¶</a></p>
</li>
          </ul>
<p id="section-4.5.2-16">A DOTS client may issue a GET message for 'config' with a 'sid'
          Uri-Path parameter to retrieve the negotiated configuration. The
          response does not need to include 'sid' in its message body.<a href="#section-4.5.2-16" class="pilcrow">¶</a></p>
</section>
</div>
<div id="update">
<section id="section-4.5.3">
          <h4 id="name-configuration-freshness-and">
<a href="#section-4.5.3" class="section-number selfRef">4.5.3. </a><a href="#name-configuration-freshness-and" class="section-name selfRef">Configuration Freshness and Notifications</a>
          </h4>
<p id="section-4.5.3-1">Max-Age Option (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.10.5" class="relref">Section 5.10.5</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>)
          <span class="bcp14">SHOULD</span> be returned by a DOTS server to associate a validity time
          with a configuration it sends. This feature forces the client to
          retrieve the updated configuration data if a change occurs at the
          DOTS server side. For example, the new configuration may instruct a
          DOTS client to cease heartbeats or reduce heartbeat frequency.<a href="#section-4.5.3-1" class="pilcrow">¶</a></p>
<p id="section-4.5.3-2">It is <span class="bcp14">NOT RECOMMENDED</span> to return a Max-Age Option set to 0.<a href="#section-4.5.3-2" class="pilcrow">¶</a></p>
<p id="section-4.5.3-3">Returning a Max-Age Option set to 2<sup>(32)</sup>-1 is equivalent to
          associating an infinite lifetime with the configuration.<a href="#section-4.5.3-3" class="pilcrow">¶</a></p>
<p id="section-4.5.3-4">If a non-zero value of Max-Age Option is received by a DOTS
          client, it <span class="bcp14">MUST</span> issue a GET request with a 'sid' Uri-Path parameter
          to retrieve the current and acceptable configuration before the
          expiry of the value enclosed in the Max-Age Option. This request is
          considered by the client and the server to be a means to refresh the
          configuration parameters for the signal channel. When a DDoS attack
          is active, refresh requests <span class="bcp14">MUST NOT</span> be sent by DOTS clients, and
          the DOTS server <span class="bcp14">MUST NOT</span> terminate the (D)TLS session after the
          expiry of the value returned in Max-Age Option.<a href="#section-4.5.3-4" class="pilcrow">¶</a></p>
<p id="section-4.5.3-5">If Max-Age Option is not returned in a response, the DOTS client
          initiates GET requests to refresh the configuration parameters each
          60 seconds (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.10.5" class="relref">Section 5.10.5</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>). To
          prevent such overload, it is <span class="bcp14">RECOMMENDED</span> that DOTS servers return a
          Max-Age Option in GET responses. Considerations related to which
          value to use and how such a value is set are implementation and
          deployment specific.<a href="#section-4.5.3-5" class="pilcrow">¶</a></p>
<p id="section-4.5.3-6">If an Observe Option set to 0 is included in the configuration
          request, the DOTS server sends notifications of any configuration
          change (<span><a href="https://www.rfc-editor.org/rfc/rfc7641#section-4.2" class="relref">Section 4.2</a> of [<a href="#RFC7641" class="xref">RFC7641</a>]</span>).<a href="#section-4.5.3-6" class="pilcrow">¶</a></p>
<p id="section-4.5.3-7">If a DOTS server detects that a misbehaving DOTS client does not
          contact the DOTS server after the expiry of Max-Age to retrieve the
          signal channel configuration data, it <span class="bcp14">MAY</span> terminate the (D)TLS
          session. A (D)TLS session is terminated by the receipt of an
          authenticated message that closes the connection (e.g., a fatal
          alert (<span><a href="https://www.rfc-editor.org/rfc/rfc8446#section-6" class="relref">Section 6</a> of [<a href="#RFC8446" class="xref">RFC8446</a>]</span>)).<a href="#section-4.5.3-7" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-4.5.4">
          <h4 id="name-delete-dots-signal-channel-">
<a href="#section-4.5.4" class="section-number selfRef">4.5.4. </a><a href="#name-delete-dots-signal-channel-" class="section-name selfRef">Delete DOTS Signal Channel Session Configuration</a>
          </h4>
<p id="section-4.5.4-1">A DELETE request is used to delete the installed DOTS signal
          channel session configuration data (<a href="#Figure15" class="xref">Figure 24</a>).<a href="#section-4.5.4-1" class="pilcrow">¶</a></p>
<span id="name-delete-configuration"></span><div id="Figure15">
<figure id="figure-24">
            <div id="section-4.5.4-2.1">
<pre class="sourcecode">
  Header: DELETE (Code=0.04)
  Uri-Path: ".well-known"
  Uri-Path: "dots"
  Uri-Path: "config"
  Uri-Path: "sid=123"
</pre>
</div>
<figcaption><a href="#figure-24" class="selfRef">Figure 24</a>:
<a href="#name-delete-configuration" class="selfRef">Delete Configuration</a>
            </figcaption></figure>
</div>
<p id="section-4.5.4-3">The DOTS server resets the DOTS signal channel session
          configuration back to the default values and acknowledges a DOTS
          client's request to remove the DOTS signal channel session
          configuration using a 2.02 (Deleted) Response Code.<a href="#section-4.5.4-3" class="pilcrow">¶</a></p>
<p id="section-4.5.4-4">Upon bootstrapping or reboot, a DOTS client <span class="bcp14">MAY</span> send a DELETE
          request to set the configuration parameters to default values. Such
          a request does not include any 'sid'.<a href="#section-4.5.4-4" class="pilcrow">¶</a></p>
</section>
</section>
</div>
<div id="redirect">
<section id="section-4.6">
        <h3 id="name-redirected-signaling">
<a href="#section-4.6" class="section-number selfRef">4.6. </a><a href="#name-redirected-signaling" class="section-name selfRef">Redirected Signaling</a>
        </h3>
<p id="section-4.6-1">Redirected DOTS signaling is discussed in detail in
        <span><a href="https://www.rfc-editor.org/rfc/rfc8811#section-3.2.2" class="relref">Section 3.2.2</a> of [<a href="#RFC8811" class="xref">RFC8811</a>]</span>.<a href="#section-4.6-1" class="pilcrow">¶</a></p>
<p id="section-4.6-2">To redirect a DOTS client to an alternative DOTS server, the DOTS
        server can return the error Response Code 5.03 (Service Unavailable)
        in response to a request from the DOTS client or convey the error
        Response Code 5.03 in a unidirectional notification response to the
        client.<a href="#section-4.6-2" class="pilcrow">¶</a></p>
<p id="section-4.6-3">The DOTS server in the error response conveys the alternate DOTS
        server's FQDN, and the alternate DOTS server's IP address(es) values
        in the CBOR body (<a href="#Figure20" class="xref">Figure 25</a>).<a href="#section-4.6-3" class="pilcrow">¶</a></p>
<span id="name-redirected-server-error-res"></span><div id="Figure20">
<figure id="figure-25">
          <div id="section-4.6-4.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:redirected-signal": {
    "alt-server": "string",
    "alt-server-record": [
       "string"
    ]
  }
}
</pre>
</div>
<figcaption><a href="#figure-25" class="selfRef">Figure 25</a>:
<a href="#name-redirected-server-error-res" class="selfRef">Redirected Server Error Response Body Schema</a>
          </figcaption></figure>
</div>
<p id="section-4.6-5">The parameters are described below:<a href="#section-4.6-5" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.6-6">
          <dt id="section-4.6-6.1">alt-server:</dt>
          <dd style="margin-left: 1.5em" id="section-4.6-6.2">
            <p id="section-4.6-6.2.1">FQDN of an alternate DOTS server.<a href="#section-4.6-6.2.1" class="pilcrow">¶</a></p>
<p id="section-4.6-6.2.2">This is a mandatory attribute.<a href="#section-4.6-6.2.2" class="pilcrow">¶</a></p>
</dd>
          <dd class="break"></dd>
<dt id="section-4.6-6.3">alt-server-record:</dt>
          <dd style="margin-left: 1.5em" id="section-4.6-6.4">
            <p id="section-4.6-6.4.1">A list of IP addresses of an
            alternate DOTS server.<a href="#section-4.6-6.4.1" class="pilcrow">¶</a></p>
<p id="section-4.6-6.4.2">This is an optional attribute.<a href="#section-4.6-6.4.2" class="pilcrow">¶</a></p>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-4.6-7">The DOTS server returns the Time to Live (TTL) of the alternate
        DOTS server in a Max-Age Option. That is, the time interval that the
        alternate DOTS server may be cached for use by a DOTS client. A Max-
        Age Option set to 2<sup>(32)</sup>-1 is equivalent to receiving an infinite TTL.
        This value means that the alternate DOTS server is to be used until
        the alternate DOTS server redirects the traffic with another 5.03
        response that conveys an alternate server's FQDN.<a href="#section-4.6-7" class="pilcrow">¶</a></p>
<p id="section-4.6-8">A Max-Age Option set to '0' may be returned for redirecting
        mitigation requests. Such a value means that the redirection applies
        only for the mitigation request in progress. Returning short TTL in a
        Max-Age Option may adversely impact DOTS clients on slow links.
        Returning short values should be avoided under such conditions.<a href="#section-4.6-8" class="pilcrow">¶</a></p>
<p id="section-4.6-9">If the alternate DOTS server TTL has expired, the DOTS client <span class="bcp14">MUST</span>
        use the DOTS server(s) that was provisioned using means discussed in
        <a href="#discover" class="xref">Section 4.1</a>. This fallback mechanism is triggered
        immediately upon expiry of the TTL, except when a DDoS attack is
        active.<a href="#section-4.6-9" class="pilcrow">¶</a></p>
<p id="section-4.6-10">Requests issued by misbehaving DOTS clients that do not honor the
        TTL conveyed in the Max-Age Option or react to explicit redirect
        messages <span class="bcp14">MAY</span> be rejected by DOTS servers.<a href="#section-4.6-10" class="pilcrow">¶</a></p>
<p id="section-4.6-11"><a href="#Figure21" class="xref">Figure 26</a> shows a 5.03 response example to
        convey the DOTS alternate server 'alt-server.example' together with
        its IP addresses 2001:db8:6401::1 and 2001:db8:6401::2.<a href="#section-4.6-11" class="pilcrow">¶</a></p>
<span id="name-example-of-redirected-serve"></span><div id="Figure21">
<figure id="figure-26">
          <div id="section-4.6-12.1">
<pre class="sourcecode">
{
  "ietf-dots-signal-channel:redirected-signal": {
    "alt-server": "alt-server.example",
    "alt-server-record": [
       "2001:db8:6401::1",
       "2001:db8:6401::2"
    ]
  }
}
</pre>
</div>
<figcaption><a href="#figure-26" class="selfRef">Figure 26</a>:
<a href="#name-example-of-redirected-serve" class="selfRef">Example of Redirected Server Error Response Body</a>
          </figcaption></figure>
</div>
<p id="section-4.6-13">When the DOTS client receives a 5.03 response with an alternate
        server included, it considers the current request to have failed, but
        it <span class="bcp14">SHOULD</span> try resending the request to the alternate DOTS server.
        During a DDoS attack, the DNS server may be the target of another DDoS
        attack; the alternate DOTS server's IP addresses conveyed in the 5.03
        response help the DOTS client skip the DNS lookup of the alternate
        DOTS server, at the cost of trusting the first DOTS server to provide
        accurate information. The DOTS client can then try to establish a UDP
        or a TCP session with the alternate DOTS server (<a href="#HE" class="xref">Section 4.3</a>). Note that state synchronization (e.g., signal
        session configuration, aliases) is assumed to be in place between the
        original and alternate DOTS servers; such synchronization means are
        out of scope. If session configuration refresh is needed while
        redirection is in place, the DOTS client follows the procedure defined
        in <a href="#update" class="xref">Section 4.5.3</a>. In 'idle' time and under some
        conditions (e.g., infinite configuration lifetime, infinite
        redirection TTL, and failure to refresh the configuration), the DOTS
        client follows the procedure defined in <a href="#convey" class="xref">Section 4.5.2</a>
        to negotiate the DOTS signal channel session configuration with the
        alternate server. The DOTS client <span class="bcp14">MAY</span> implement a method to construct
        IPv4-embedded IPv6 addresses <span>[<a href="#RFC6052" class="xref">RFC6052</a>]</span>; this is
        required to handle the scenario where an IPv6-only DOTS client
        communicates with an IPv4-only alternate DOTS server.<a href="#section-4.6-13" class="pilcrow">¶</a></p>
<p id="section-4.6-14">If the DOTS client has been redirected to a DOTS server with which
        it has already communicated within the last five (5) minutes, it <span class="bcp14">MUST</span>
        ignore the redirection and try to contact other DOTS servers listed in
        the local configuration or discovered using dynamic means, such as DHCP
        or SRV procedures <span>[<a href="#RFC8973" class="xref">RFC8973</a>]</span>. It is <span class="bcp14">RECOMMENDED</span>
        that DOTS clients support the means to alert administrators about
        redirect loops.<a href="#section-4.6-14" class="pilcrow">¶</a></p>
</section>
</div>
<div id="hb">
<section id="section-4.7">
        <h3 id="name-heartbeat-mechanism">
<a href="#section-4.7" class="section-number selfRef">4.7. </a><a href="#name-heartbeat-mechanism" class="section-name selfRef">Heartbeat Mechanism</a>
        </h3>
<p id="section-4.7-1">To provide an indication of signal health and to distinguish an
        'idle' signal channel from a 'disconnected' or 'defunct' session, the
        DOTS agent sends a heartbeat over the signal channel to maintain its
        half of the channel (also, aligned with the "consents" recommendation
        in <span><a href="https://www.rfc-editor.org/rfc/rfc8085#section-6" class="relref">Section 6</a> of [<a href="#RFC8085" class="xref">RFC8085</a>]</span>). The DOTS agent
        similarly expects a heartbeat from its peer DOTS agent, and it may
        consider a session terminated in the prolonged absence of a peer agent
        heartbeat. Concretely, while the communication between the DOTS agents
        is otherwise quiescent, the DOTS client will probe the DOTS server to
        ensure it has maintained cryptographic state and vice versa. Such
        probes can also keep the bindings of firewalls and/or stateful
        translators alive. This probing reduces the frequency of establishing
        a new handshake when a DOTS signal needs to be conveyed to the DOTS
        server.<a href="#section-4.7-1" class="pilcrow">¶</a></p>
<aside id="section-4.7-2">
          <p id="section-4.7-2.1">Implementation Note: Given that CoAP roles can be multiplexed
        over the same session as discussed in [RFC7252] and are already
        supported by CoAP implementations, both the DOTS client and
        server can send DOTS heartbeat requests.<a href="#section-4.7-2.1" class="pilcrow">¶</a></p>
</aside>
<p id="section-4.7-3">The DOTS heartbeat mechanism uses Non-confirmable PUT requests
        (<a href="#hbreq" class="xref">Figure 27</a>) with an expected 2.04 (Changed)
        Response Code (<a href="#hbrep" class="xref">Figure 28</a>). This procedure occurs
        between a DOTS agent and its immediate peer DOTS agent. As such, this
        PUT request <span class="bcp14">MUST NOT</span> be relayed by a DOTS gateway. The PUT request
        used for DOTS heartbeat <span class="bcp14">MUST NOT</span> have a 'cuid', 'cdid', or 'mid'
        Uri-Path.<a href="#section-4.7-3" class="pilcrow">¶</a></p>
<span id="name-put-to-check-peer-dots-agen"></span><div id="hbreq">
<figure id="figure-27">
          <div id="section-4.7-4.1">
<pre class="sourcecode">
     Header: PUT (Code=0.03)
     Uri-Path: ".well-known"
     Uri-Path: "dots"
     Uri-Path: "hb"
     Content-Format: "application/dots+cbor"

     {
       "ietf-dots-signal-channel:heartbeat": {
          "peer-hb-status": true
        }
     }
</pre>
</div>
<figcaption><a href="#figure-27" class="selfRef">Figure 27</a>:
<a href="#name-put-to-check-peer-dots-agen" class="selfRef">PUT to Check Peer DOTS Agent Is Responding</a>
          </figcaption></figure>
</div>
<p id="section-4.7-5">The mandatory 'peer-hb-status' attribute is set to 'true' (or
        'false') to indicate that a DOTS agent is (or is not) receiving
        heartbeat messages from its peer in the last (2 * 'heartbeat-
        interval') period. Such information can be used by a peer DOTS agent
        to detect or confirm connectivity issues and react accordingly. For
        example, if a DOTS client receives a 2.04 response for its heartbeat
        messages but no server-initiated heartbeat messages, the DOTS client
        sets 'peer-hb-status' to 'false' in its next heartbeat message. Upon
        receipt of this message, the DOTS server then will need to try another
        strategy for sending the heartbeats (e.g., adjust the heartbeat
        interval or send a server-initiated heartbeat immediately after
        receiving a client-initiated heartbeat message).<a href="#section-4.7-5" class="pilcrow">¶</a></p>
<span id="name-response-to-a-dots-heartbea"></span><div id="hbrep">
<figure id="figure-28">
          <div id="section-4.7-6.1">
<pre class="sourcecode">
     Header: (Code=2.04)
</pre>
</div>
<figcaption><a href="#figure-28" class="selfRef">Figure 28</a>:
<a href="#name-response-to-a-dots-heartbea" class="selfRef">Response to a DOTS Heartbeat Request (with an Empty Body)</a>
          </figcaption></figure>
</div>
<p id="section-4.7-7">DOTS servers <span class="bcp14">MAY</span> trigger their heartbeat requests immediately after
        receiving heartbeat probes from peer DOTS clients. It is the
        responsibility of DOTS clients to ensure that on-path
        translators/firewalls are maintaining a binding so that the same
        external IP address and/or port number is retained for the DOTS signal
        channel session.<a href="#section-4.7-7" class="pilcrow">¶</a></p>
<p id="section-4.7-8">Under normal traffic conditions (i.e., no attack is ongoing), if a
        DOTS agent does not receive any response from the peer DOTS agent for
        'missing-hb-allowed' number of consecutive heartbeat messages, it
        concludes that the DOTS signal channel session is disconnected. The
        DOTS client <span class="bcp14">MUST</span> then try to reestablish the DOTS signal channel
        session, preferably by resuming the (D)TLS session.<a href="#section-4.7-8" class="pilcrow">¶</a></p>
<aside id="section-4.7-9">
          <p id="section-4.7-9.1">Note: If a new DOTS signal channel session cannot be
    established, the DOTS client <span class="bcp14">SHOULD NOT</span> retry to establish the
    DOTS signal channel session more frequently than every 300
    seconds (5 minutes) and <span class="bcp14">MUST NOT</span> retry more frequently than
    every 60 seconds (1 minute).  It is recommended that DOTS
    clients support the means to alert administrators about the
    failure to establish a (D)TLS session.<a href="#section-4.7-9.1" class="pilcrow">¶</a></p>
</aside>
<p id="section-4.7-10">In case of a massive DDoS attack that saturates the incoming
        link(s) to the DOTS client, all traffic from the DOTS server to the
        DOTS client will likely be dropped, although the DOTS server receives
        heartbeat requests in addition to DOTS messages sent by the DOTS
        client. In this scenario, DOTS clients <span class="bcp14">MUST</span> behave differently to
        handle message transmission and DOTS signal channel session liveliness
        during link saturation:<a href="#section-4.7-10" class="pilcrow">¶</a></p>
<p style="margin-left: 2.5em" id="section-4.7-11">The DOTS client <span class="bcp14">MUST NOT</span> consider the DOTS signal channel
            session terminated even after a maximum 'missing-hb-allowed'
            threshold is reached. The DOTS client <span class="bcp14">SHOULD</span> keep on using the
            current DOTS signal channel session to send heartbeat requests
            over it so that the DOTS server knows the DOTS client has not
            disconnected the DOTS signal channel session.<a href="#section-4.7-11" class="pilcrow">¶</a></p>
<p style="margin-left: 2.5em" id="section-4.7-12">After the maximum 'missing-hb-allowed' threshold
            is reached, the DOTS client <span class="bcp14">SHOULD</span> try to establish a new DOTS
            signal channel session. The DOTS client <span class="bcp14">SHOULD</span> send mitigation
            requests over the current DOTS signal channel session and, in
            parallel, send the mitigation requests over the new DOTS signal
            channel session. This may be handled, for example, by resumption
            of the (D)TLS session or using 0-RTT mode in DTLS 1.3 to piggyback
            the mitigation request in the ClientHello message.<a href="#section-4.7-12" class="pilcrow">¶</a></p>
<p style="margin-left: 2.5em" id="section-4.7-13">As soon as the link is no longer
            saturated, if traffic from the DOTS server reaches the DOTS client
            over the current DOTS signal channel session, the DOTS client can
            stop the new DOTS signal channel session attempt or if a new DOTS
            signal channel session is successful then disconnect the current
            DOTS signal channel session.<a href="#section-4.7-13" class="pilcrow">¶</a></p>
<p id="section-4.7-14">If the DOTS server receives traffic from the peer DOTS client
        (e.g., peer DOTS client-initiated heartbeats) but the maximum
        'missing-hb- allowed' threshold is reached, the DOTS server <span class="bcp14">MUST NOT</span>
        consider the DOTS signal channel session disconnected. The DOTS server
        <span class="bcp14">MUST</span> keep on using the current DOTS signal channel session so that the
        DOTS client can send mitigation requests over the current DOTS signal
        channel session. In this case, the DOTS server can identify that the
        DOTS client is under attack and that the inbound link to the DOTS
        client (domain) is saturated. Furthermore, if the DOTS server does not
        receive a mitigation request from the DOTS client, it implies that the
        DOTS client has not detected the attack or, if an attack mitigation is
        in progress, it implies that the applied DDoS mitigation actions are
        not yet effectively handling the DDoS attack volume.<a href="#section-4.7-14" class="pilcrow">¶</a></p>
<p id="section-4.7-15">If the DOTS server does not receive any traffic from the peer DOTS
        client during the time span required to exhaust the maximum
        'missing-hb-allowed' threshold, the DOTS server concludes the session
        is disconnected. The DOTS server can then trigger preconfigured
        mitigation requests for this DOTS client (if any).<a href="#section-4.7-15" class="pilcrow">¶</a></p>
<p id="section-4.7-16">In DOTS over TCP, the sender of a DOTS heartbeat message has to
        allow up to 'heartbeat-interval' seconds when waiting for a heartbeat
        reply. When a failure is detected by a DOTS client, it proceeds with
        the session recovery, following the same approach as the one used for
        unreliable transports.<a href="#section-4.7-16" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="YANG">
<section id="section-5">
      <h2 id="name-dots-signal-channel-yang-mo">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-dots-signal-channel-yang-mo" class="section-name selfRef">DOTS Signal Channel YANG Modules</a>
      </h2>
<p id="section-5-1">This document defines a YANG module <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>
      for DOTS mitigation scope, DOTS signal channel session configuration
      data, DOTS redirection signaling, and DOTS heartbeats.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">This YANG module is not intended to be used via NETCONF/RESTCONF for
      DOTS server management purposes; such a module is out of the scope of
      this document. It serves only to provide abstract data structures. This
      document uses the "structure" extension specified in <span>[<a href="#RFC8791" class="xref">RFC8791</a>]</span>.<a href="#section-5-2" class="pilcrow">¶</a></p>
<p id="section-5-3">A companion YANG module is defined to include a collection of types
      defined by IANA: "iana-dots-signal-channel" (<a href="#iana-yang" class="xref">Section 5.2</a>).<a href="#section-5-3" class="pilcrow">¶</a></p>
<div id="tree">
<section id="section-5.1">
        <h3 id="name-tree-structure">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-tree-structure" class="section-name selfRef">Tree Structure</a>
        </h3>
<p id="section-5.1-1">This document defines the YANG module "ietf-dots-signal-channel",
        which has the following tree structure. A DOTS signal message can be a
        mitigation, a configuration, a redirect, or a heartbeat message.<a href="#section-5.1-1" class="pilcrow">¶</a></p>
<p id="section-5.1-2">This tree structure obsoletes the one described in
        <span><a href="https://www.rfc-editor.org/rfc/rfc8782#section-5.1" class="relref">Section 5.1</a> of [<a href="#RFC8782" class="xref">RFC8782</a>]</span>.<a href="#section-5.1-2" class="pilcrow">¶</a></p>
<div id="section-5.1-3">
<pre class="sourcecode lang-yangtree">
module: ietf-dots-signal-channel

  structure dots-signal:
    +-- (message-type)?
       +--:(mitigation-scope)
       |  +-- scope* []
       |     +-- target-prefix*                inet:ip-prefix
       |     +-- target-port-range* [lower-port]
       |     |  +-- lower-port    inet:port-number
       |     |  +-- upper-port?   inet:port-number
       |     +-- target-protocol*              uint8
       |     +-- target-fqdn*                  inet:domain-name
       |     +-- target-uri*                   inet:uri
       |     +-- alias-name*                   string
       |     +-- lifetime?                     union
       |     +-- trigger-mitigation?           boolean
       |     +-- (direction)?
       |        +--:(server-to-client-only)
       |        |  +-- mid?                    uint32
       |        |  +-- mitigation-start?       uint64
       |        |  +-- status?
       |        |  |       iana-dots-signal:status
       |        |  +-- conflict-information
       |        |  |  +-- conflict-status?
       |        |  |  |       iana-dots-signal:conflict-status
       |        |  |  +-- conflict-cause?
       |        |  |  |       iana-dots-signal:conflict-cause
       |        |  |  +-- retry-timer?       uint32
       |        |  |  +-- conflict-scope
       |        |  |     +-- target-prefix*       inet:ip-prefix
       |        |  |     +-- target-port-range* [lower-port]
       |        |  |     |  +-- lower-port    inet:port-number
       |        |  |     |  +-- upper-port?   inet:port-number
       |        |  |     +-- target-protocol*     uint8
       |        |  |     +-- target-fqdn*         inet:domain-name
       |        |  |     +-- target-uri*          inet:uri
       |        |  |     +-- alias-name*          string
       |        |  |     +-- acl-list* [acl-name]
       |        |  |     |  +-- acl-name    leafref
       |        |  |     |  +-- acl-type?   leafref
       |        |  |     +-- mid?                 uint32
       |        |  +-- bytes-dropped?
       |        |  |       yang:zero-based-counter64
       |        |  +-- bps-dropped?            yang:gauge64
       |        |  +-- pkts-dropped?
       |        |  |       yang:zero-based-counter64
       |        |  +-- pps-dropped?            yang:gauge64
       |        +--:(client-to-server-only)
       |           +-- attack-status?
       |                   iana-dots-signal:attack-status
       +--:(signal-config)
       |  +-- mitigating-config
       |  |  +-- heartbeat-interval
       |  |  |  +-- (direction)?
       |  |  |  |  +--:(server-to-client-only)
       |  |  |  |     +-- max-value?   uint16
       |  |  |  |     +-- min-value?   uint16
       |  |  |  +-- current-value?     uint16
       |  |  +-- missing-hb-allowed
       |  |  |  +-- (direction)?
       |  |  |  |  +--:(server-to-client-only)
       |  |  |  |     +-- max-value?   uint16
       |  |  |  |     +-- min-value?   uint16
       |  |  |  +-- current-value?     uint16
       |  |  +-- probing-rate
       |  |  |  +-- (direction)?
       |  |  |  |  +--:(server-to-client-only)
       |  |  |  |     +-- max-value?   uint16
       |  |  |  |     +-- min-value?   uint16
       |  |  |  +-- current-value?     uint16
       |  |  +-- max-retransmit
       |  |  |  +-- (direction)?
       |  |  |  |  +--:(server-to-client-only)
       |  |  |  |     +-- max-value?   uint16
       |  |  |  |     +-- min-value?   uint16
       |  |  |  +-- current-value?     uint16
       |  |  +-- ack-timeout
       |  |  |  +-- (direction)?
       |  |  |  |  +--:(server-to-client-only)
       |  |  |  |     +-- max-value-decimal?   decimal64
       |  |  |  |     +-- min-value-decimal?   decimal64
       |  |  |  +-- current-value-decimal?     decimal64
       |  |  +-- ack-random-factor
       |  |     +-- (direction)?
       |  |     |  +--:(server-to-client-only)
       |  |     |     +-- max-value-decimal?   decimal64
       |  |     |     +-- min-value-decimal?   decimal64
       |  |     +-- current-value-decimal?     decimal64
       |  +-- idle-config
       |     +-- heartbeat-interval
       |     |  +-- (direction)?
       |     |  |  +--:(server-to-client-only)
       |     |  |     +-- max-value?   uint16
       |     |  |     +-- min-value?   uint16
       |     |  +-- current-value?     uint16
       |     +-- missing-hb-allowed
       |     |  +-- (direction)?
       |     |  |  +--:(server-to-client-only)
       |     |  |     +-- max-value?   uint16
       |     |  |     +-- min-value?   uint16
       |     |  +-- current-value?     uint16
       |     +-- probing-rate
       |     |  +-- (direction)?
       |     |  |  +--:(server-to-client-only)
       |     |  |     +-- max-value?   uint16
       |     |  |     +-- min-value?   uint16
       |     |  +-- current-value?     uint16
       |     +-- max-retransmit
       |     |  +-- (direction)?
       |     |  |  +--:(server-to-client-only)
       |     |  |     +-- max-value?   uint16
       |     |  |     +-- min-value?   uint16
       |     |  +-- current-value?     uint16
       |     +-- ack-timeout
       |     |  +-- (direction)?
       |     |  |  +--:(server-to-client-only)
       |     |  |     +-- max-value-decimal?   decimal64
       |     |  |     +-- min-value-decimal?   decimal64
       |     |  +-- current-value-decimal?     decimal64
       |     +-- ack-random-factor
       |        +-- (direction)?
       |        |  +--:(server-to-client-only)
       |        |     +-- max-value-decimal?   decimal64
       |        |     +-- min-value-decimal?   decimal64
       |        +-- current-value-decimal?     decimal64
       +--:(redirected-signal)
       |  +-- (direction)?
       |     +--:(server-to-client-only)
       |        +-- alt-server           inet:domain-name
       |        +-- alt-server-record*   inet:ip-address
       +--:(heartbeat)
          +-- peer-hb-status             boolean
</pre><a href="#section-5.1-3" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="iana-yang">
<section id="section-5.2">
        <h3 id="name-iana-dots-signal-channel-ya">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-iana-dots-signal-channel-ya" class="section-name selfRef">IANA DOTS Signal Channel YANG Module</a>
        </h3>
<p id="section-5.2-1">This version obsoletes the version described in
        <span><a href="https://www.rfc-editor.org/rfc/rfc8782#section-5.2" class="relref">Section 5.2</a> of [<a href="#RFC8782" class="xref">RFC8782</a>]</span>.<a href="#section-5.2-1" class="pilcrow">¶</a></p>
<div id="section-5.2-2">
<pre class="sourcecode lang-yang">&lt;CODE BEGINS&gt; file "iana-dots-signal-channel@2021-09-02.yang"


module iana-dots-signal-channel {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:iana-dots-signal-channel";
  prefix iana-dots-signal;

  organization
    "IANA";
  contact
    "Internet Assigned Numbers Authority

     Postal: ICANN
          12025 Waterfront Drive, Suite 300
          Los Angeles, CA  90094-2536
          United States of America
     Tel:    +1 310 301 5800
     &lt;mailto:iana@iana.org&gt;";
  description
    "This module contains a collection of YANG data types defined
     by IANA and used for DOTS signal channel protocol.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9132; see
     the RFC itself for full legal notices.";

  revision 2021-09-02 {
    description
      "Updated the prefix used for the module.";
    reference
      "RFC 9132: Distributed Denial-of-Service Open Threat
                 Signaling (DOTS) Signal Channel Specification";
  }

  revision 2020-05-28 {
    description
      "Initial revision.";
    reference
      "RFC 8782: Distributed Denial-of-Service Open Threat
                 Signaling (DOTS) Signal Channel Specification";
  }

  typedef status {
    type enumeration {
      enum attack-mitigation-in-progress {
        value 1;
        description
          "Attack mitigation setup is in progress (e.g., changing
           the network path to reroute the inbound traffic
           to DOTS mitigator).";
      }
      enum attack-successfully-mitigated {
        value 2;
        description
          "Attack is being successfully mitigated (e.g., traffic
           is redirected to a DDoS mitigator and attack
           traffic is dropped).";
      }
      enum attack-stopped {
        value 3;
        description
          "Attack has stopped and the DOTS client can
           withdraw the mitigation request.";
      }
      enum attack-exceeded-capability {
        value 4;
        description
          "Attack has exceeded the mitigation provider
           capability.";
      }
      enum dots-client-withdrawn-mitigation {
        value 5;
        description
          "DOTS client has withdrawn the mitigation
           request and the mitigation is active but
           terminating.";
      }
      enum attack-mitigation-terminated {
        value 6;
        description
          "Attack mitigation is now terminated.";
      }
      enum attack-mitigation-withdrawn {
        value 7;
        description
          "Attack mitigation is withdrawn.";
      }
      enum attack-mitigation-signal-loss {
        value 8;
        description
          "Attack mitigation will be triggered
           for the mitigation request only when
           the DOTS signal channel session is lost.";
      }
    }
    description
      "Enumeration for status reported by the DOTS server.";
  }

  typedef conflict-status {
    type enumeration {
      enum request-inactive-other-active {
        value 1;
        description
          "DOTS server has detected conflicting mitigation
           requests from different DOTS clients.
           This mitigation request is currently inactive
           until the conflicts are resolved.  Another
           mitigation request is active.";
      }
      enum request-active {
        value 2;
        description
          "DOTS server has detected conflicting mitigation
           requests from different DOTS clients.
           This mitigation request is currently active.";
      }
      enum all-requests-inactive {
        value 3;
        description
          "DOTS server has detected conflicting mitigation
           requests from different DOTS clients.  All
           conflicting mitigation requests are inactive.";
      }
    }
    description
      "Enumeration for conflict status.";
  }

  typedef conflict-cause {
    type enumeration {
      enum overlapping-targets {
        value 1;
        description
          "Overlapping targets. conflict-scope provides
           more details about the exact conflict.";
      }
      enum conflict-with-acceptlist {
        value 2;
        description
          "Conflicts with an existing accept-list.

           This code is returned when the DDoS mitigation
           detects that some of the source addresses/prefixes
           listed in the accept-list ACLs are actually
           attacking the target.";
      }
      enum cuid-collision {
        value 3;
        description
          "Conflicts with the cuid used by another
           DOTS client.";
      }
    }
    description
      "Enumeration for conflict causes.";
  }

  typedef attack-status {
    type enumeration {
      enum under-attack {
        value 1;
        description
          "The DOTS client determines that it is still under
           attack.";
      }
      enum attack-successfully-mitigated {
        value 2;
        description
          "The DOTS client determines that the attack is
           successfully mitigated.";
      }
    }
    description
      "Enumeration for attack status codes.";
  }
}

&lt;CODE ENDS&gt;</pre><a href="#section-5.2-2" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="yrequest">
<section id="section-5.3">
        <h3 id="name-ietf-dots-signal-channel-ya">
<a href="#section-5.3" class="section-number selfRef">5.3. </a><a href="#name-ietf-dots-signal-channel-ya" class="section-name selfRef">IETF DOTS Signal Channel YANG Module</a>
        </h3>
<p id="section-5.3-1">This module uses the common YANG types defined in <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span> and types defined in <span>[<a href="#RFC8783" class="xref">RFC8783</a>]</span>.<a href="#section-5.3-1" class="pilcrow">¶</a></p>
<p id="section-5.3-2">This version obsoletes the version described in
        <span><a href="https://www.rfc-editor.org/rfc/rfc8782#section-5.3" class="relref">Section 5.3</a> of [<a href="#RFC8782" class="xref">RFC8782</a>]</span>.<a href="#section-5.3-2" class="pilcrow">¶</a></p>
<div id="section-5.3-3">
<pre class="sourcecode lang-yang">&lt;CODE BEGINS&gt; file "ietf-dots-signal-channel@2021-09-02.yang"


module ietf-dots-signal-channel {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-dots-signal-channel";
  prefix dots-signal;

  import ietf-inet-types {
    prefix inet;
    reference
      "Section 4 of RFC 6991";
  }
  import ietf-yang-types {
    prefix yang;
    reference
      "Section 3 of RFC 6991";
  }
  import ietf-dots-data-channel {
    prefix data-channel;
    reference
      "RFC 8783: Distributed Denial-of-Service Open Threat Signaling
                 (DOTS) Data Channel Specification";
  }
  import iana-dots-signal-channel {
    prefix iana-dots-signal;
    reference
      "RFC 9132: Distributed Denial-of-Service Open Threat Signaling
                 (DOTS) Signal Channel Specification";
  }
  import ietf-yang-structure-ext {
    prefix sx;
    reference
      "RFC 8791: YANG Data Structure Extensions";
  }

  organization
    "IETF DDoS Open Threat Signaling (DOTS) Working Group";
  contact
    "WG Web:   &lt;https://datatracker.ietf.org/wg/dots/&gt;
     WG List:  &lt;mailto:dots@ietf.org&gt;

     Editor:  Mohamed Boucadair
              &lt;mailto:mohamed.boucadair@orange.com&gt;

     Editor:  Jon Shallow
              &lt;mailto:supjps-ietf@jpshallow.com&gt;

     Author:  Konda, Tirumaleswar Reddy.K
              &lt;mailto:kondtir@gmail.com&gt;

     Author:  Prashanth Patil
              &lt;mailto:praspati@cisco.com&gt;

     Author:  Andrew Mortensen
              &lt;mailto:amortensen@arbor.net&gt;

     Author:  Nik Teague
              &lt;mailto:nteague@ironmountain.co.uk&gt;";
  description
    "This module contains YANG definition for the signaling
     messages exchanged between a DOTS client and a DOTS server.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9132; see
     the RFC itself for full legal notices.";

  revision 2021-09-02 {
    description
      "Updated revision to comply with RFC 8791.

       This version is not backward compatible with the version
       published in RFC 8782.";
    reference
      "RFC 9132: Distributed Denial-of-Service Open Threat
                 Signaling (DOTS) Signal Channel Specification";
  }
  revision 2020-05-28 {
    description
      "Initial revision.";
    reference
      "RFC 8782: Distributed Denial-of-Service Open Threat
                 Signaling (DOTS) Signal Channel Specification";
  }

  /*
   * Groupings
   */

  grouping mitigation-scope {
    description
      "Specifies the scope of the mitigation request.";
    list scope {
      description
        "The scope of the request.";
      uses data-channel:target;
      leaf-list alias-name {
        type string;
        description
          "An alias name that points to a resource.";
      }
      leaf lifetime {
        type union {
          type uint32;
          type int32 {
            range "-1";
          }
        }
        units "seconds";
        default "3600";
        description
          "Indicates the lifetime of the mitigation request.

           A lifetime of '0' in a mitigation request is an
           invalid value.

           A lifetime of negative one (-1) indicates indefinite
           lifetime for the mitigation request.

           Lifetime is mandatory in a mitigation request.

           The DOTS server must always indicate the actual lifetime
           in the response to an accepted mitigation request and the
           remaining lifetime in status messages sent to the
           DOTS client.";
      }
      leaf trigger-mitigation {
        type boolean;
        default "true";
        description
          "If set to 'false', DDoS mitigation will not be
           triggered unless the DOTS signal channel
           session is lost.";
      }
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf mid {
            type uint32;
            description
              "Mitigation request identifier.

               This identifier must be unique for each mitigation
               request bound to the DOTS client.";
          }
          leaf mitigation-start {
            type uint64;
            description
              "Mitigation start time is represented in seconds
               relative to 1970-01-01T00:00:00Z in UTC time.

               This is a mandatory attribute when an attack
               mitigation is active.  It must not be returned for
               a mitigation with 'status' code set to 8.";
          }
          leaf status {
            type iana-dots-signal:status;
            description
              "Indicates the status of a mitigation request.
               It must be included in responses only.

               This is a mandatory attribute if a mitigation
               request is accepted and processed by the server.";
          }
          container conflict-information {
            description
              "Indicates that a conflict is detected.";
            leaf conflict-status {
              type iana-dots-signal:conflict-status;
              description
                "Indicates the conflict status.";
            }
            leaf conflict-cause {
              type iana-dots-signal:conflict-cause;
              description
                "Indicates the cause of the conflict.";
            }
            leaf retry-timer {
              type uint32;
              units "seconds";
              description
                "The DOTS client must not resend the
                 same request that has a conflict before the expiry
                 of this timer.";
            }
            container conflict-scope {
              description
                "Provides more information about the conflict
                 scope.";
              uses data-channel:target {
                when "/dots-signal/scope/conflict-information/"
                   + "conflict-cause = 'overlapping-targets'";
              }
              leaf-list alias-name {
                when "../../conflict-cause = 'overlapping-targets'";
                type string;
                description
                  "Conflicting alias-name.";
              }
              list acl-list {
                when "../../conflict-cause ="
                   + " 'conflict-with-acceptlist'";
                key "acl-name";
                description
                  "List of conflicting ACLs, as defined in the DOTS
                   data channel.  These ACLs are uniquely defined by
                   cuid and acl-name.";
                leaf acl-name {
                  type leafref {
                    path "/data-channel:dots-data"
                       + "/data-channel:dots-client"
                       + "/data-channel:acls"
                       + "/data-channel:acl/data-channel:name";
                  }
                  description
                    "Reference to the conflicting ACL name bound to
                     a DOTS client.";
                }
                leaf acl-type {
                  type leafref {
                    path "/data-channel:dots-data"
                       + "/data-channel:dots-client"
                       + "/data-channel:acls"
                       + "/data-channel:acl/data-channel:type";
                  }
                  description
                    "Reference to the conflicting ACL type bound to
                     a DOTS client.";
                }
              }
              leaf mid {
                when "../../conflict-cause = 'overlapping-targets'";
                type uint32;
                description
                  "Reference to the conflicting 'mid' bound to
                   the same DOTS client.";
              }
            }
          }
          leaf bytes-dropped {
            type yang:zero-based-counter64;
            units "bytes";
            description
              "The total dropped byte count for the mitigation
               request since the attack mitigation was triggered.
               The count wraps around when it reaches the maximum
               value of counter64 for dropped bytes.";
          }
          leaf bps-dropped {
            type yang:gauge64;
            units "bytes per second";
            description
              "The average number of dropped bytes per second for
               the mitigation request since the attack
               mitigation was triggered.  This should be over
               five-minute intervals (that is, measuring bytes
               into five-minute buckets and then averaging these
               buckets over the time since the mitigation was
               triggered).";
          }
          leaf pkts-dropped {
            type yang:zero-based-counter64;
            description
              "The total number of dropped packet count for the
               mitigation request since the attack mitigation was
               triggered.  The count wraps around when it reaches
               the maximum value of counter64 for dropped packets.";
          }
          leaf pps-dropped {
            type yang:gauge64;
            units "packets per second";
            description
              "The average number of dropped packets per second
               for the mitigation request since the attack
               mitigation was triggered.  This should be over
               five-minute intervals (that is, measuring packets
               into five-minute buckets and then averaging these
               buckets over the time since the mitigation was
               triggered).";
          }
        }
        case client-to-server-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the client to the server.";
          leaf attack-status {
            type iana-dots-signal:attack-status;
            description
              "Indicates the status of an attack as seen by the
               DOTS client.

               This is a mandatory attribute when a client
               performs an efficacy update.";
          }
        }
      }
    }
  }

  grouping config-parameters {
    description
      "Subset of DOTS signal channel session configuration.";
    container heartbeat-interval {
      description
        "DOTS agents regularly send heartbeats to each other
         after mutual authentication is successfully
         completed in order to keep the DOTS signal channel
         open.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value {
            type uint16;
            units "seconds";
            description
              "Maximum acceptable heartbeat-interval value.";
          }
          leaf min-value {
            type uint16;
            units "seconds";
            description
              "Minimum acceptable heartbeat-interval value.";
          }
        }
      }
      leaf current-value {
        type uint16;
        units "seconds";
        default "30";
        description
          "Current heartbeat-interval value.

           '0' means that heartbeat mechanism is deactivated.";
      }
    }
    container missing-hb-allowed {
      description
        "Maximum number of missing heartbeats allowed.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value {
            type uint16;
            description
              "Maximum acceptable missing-hb-allowed value.";
          }
          leaf min-value {
            type uint16;
            description
              "Minimum acceptable missing-hb-allowed value.";
          }
        }
      }
      leaf current-value {
        type uint16;
        default "15";
        description
          "Current missing-hb-allowed value.";
      }
    }
    container probing-rate {
      description
        "The limit for sending Non-confirmable messages with
         no response.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value {
            type uint16;
            units "byte/second";
            description
              "Maximum acceptable probing-rate value.";
          }
          leaf min-value {
            type uint16;
            units "byte/second";
            description
              "Minimum acceptable probing-rate value.";
          }
        }
      }
      leaf current-value {
        type uint16;
        units "byte/second";
        default "5";
        description
          "Current probing-rate value.";
      }
    }
    container max-retransmit {
      description
        "Maximum number of retransmissions of a Confirmable
         message.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value {
            type uint16;
            description
              "Maximum acceptable max-retransmit value.";
          }
          leaf min-value {
            type uint16;
            description
              "Minimum acceptable max-retransmit value.";
          }
        }
      }
      leaf current-value {
        type uint16;
        default "3";
        description
          "Current max-retransmit value.";
      }
    }
    container ack-timeout {
      description
        "Initial retransmission timeout value.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            description
              "Maximum ack-timeout value.";
          }
          leaf min-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            units "seconds";
            description
              "Minimum ack-timeout value.";
          }
        }
      }
      leaf current-value-decimal {
        type decimal64 {
          fraction-digits 2;
        }
        units "seconds";
        default "2";
        description
          "Current ack-timeout value.";
      }
    }
    container ack-random-factor {
      description
        "Random factor used to influence the timing of
         retransmissions.";
      choice direction {
        description
          "Indicates the communication direction in which the
           data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
             sent from the server to the client.";
          leaf max-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            description
              "Maximum acceptable ack-random-factor value.";
          }
          leaf min-value-decimal {
            type decimal64 {
              fraction-digits 2;
            }
            description
              "Minimum acceptable ack-random-factor value.";
          }
        }
      }
      leaf current-value-decimal {
        type decimal64 {
          fraction-digits 2;
        }
        default "1.5";
        description
          "Current ack-random-factor value.";
      }
    }
  }

  grouping signal-config {
    description
      "DOTS signal channel session configuration.";
    container mitigating-config {
      description
        "Configuration parameters to use when a mitigation
         is active.";
      uses config-parameters;
    }
    container idle-config {
      description
        "Configuration parameters to use when no mitigation
         is active.";
      uses config-parameters;
    }
  }

  grouping redirected-signal {
    description
      "Grouping for the redirected signaling.";
    choice direction {
      description
        "Indicates the communication direction in which the
         data nodes can be included.";
      case server-to-client-only {
        description
          "These data nodes appear only in a mitigation message
           sent from the server to the client.";
        leaf alt-server {
          type inet:domain-name;
          mandatory true;
          description
            "FQDN of an alternate server.";
        }
        leaf-list alt-server-record {
          type inet:ip-address;
          description
            "List of records for the alternate server.";
        }
      }
    }
  }

  /*
   * DOTS Signal Channel Structure
   */

  sx:structure dots-signal {
    description
      "Main structure for DOTS signal message.

       A DOTS signal message can be a mitigation, a configuration,
       a redirected, or a heartbeat signal message.";
    choice message-type {
      description
        "Can be a mitigation, a configuration, a redirect, or
         a heartbeat message.";
      case mitigation-scope {
        description
          "Mitigation scope of a mitigation message.";
        uses mitigation-scope;
      }
      case signal-config {
        description
          "Configuration message.";
        uses signal-config;
      }
      case redirected-signal {
        description
          "Redirected signaling.";
        uses redirected-signal;
      }
      case heartbeat {
        description
          "DOTS heartbeats.";
        leaf peer-hb-status {
          type boolean;
          mandatory true;
          description
            "Indicates whether a DOTS agent receives heartbeats
             from its peer.  The value is set to 'true' if the
             DOTS agent is receiving heartbeat messages
             from its peer.";
        }
      }
    }
  }
}

&lt;CODE ENDS&gt;</pre><a href="#section-5.3-3" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="mapping">
<section id="section-6">
      <h2 id="name-yang-json-mapping-parameter">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-yang-json-mapping-parameter" class="section-name selfRef">YANG/JSON Mapping Parameters to CBOR</a>
      </h2>
<p id="section-6-1">All parameters in the payload of the DOTS signal channel <span class="bcp14">MUST</span> be
      mapped to CBOR types, as shown in <a href="#table5" class="xref">Table 5</a>, and are 
      assigned an integer key to save space.<a href="#section-6-1" class="pilcrow">¶</a></p>
<p style="margin-left: 1.5em" id="section-6-2">Note: Implementers must check that the mapping output provided by
          their YANG-to-CBOR encoding schemes is aligned with the content of
          <a href="#table5" class="xref">Table 5</a>. For example, some CBOR and 
   JSON types for enumerations and
          the 64-bit quantities can differ depending on the encoder used.<a href="#section-6-2" class="pilcrow">¶</a></p>
<p id="section-6-3">The CBOR key values are divided into two types:
      comprehension-required and comprehension-optional. DOTS agents can
      safely ignore comprehension-optional values they don't understand, but
      they cannot successfully process a request if it contains
      comprehension-required values that are not understood. The 4.00 response
      <span class="bcp14">SHOULD</span> include a diagnostic payload describing the unknown
      comprehension-required CBOR key values. The initial set of CBOR key
      values defined in this specification are of type
      comprehension-required.<a href="#section-6-3" class="pilcrow">¶</a></p>
<span id="name-cbor-key-values-used-in-dot"></span><div id="table5">
<table class="center" id="table-5">
        <caption>
<a href="#table-5" class="selfRef">Table 5</a>:
<a href="#name-cbor-key-values-used-in-dot" class="selfRef">CBOR Key Values Used in DOTS Signal Channel Messages &amp; Their Mappings to JSON and YANG</a>
        </caption>
<thead>
          <tr>
            <th class="text-left" rowspan="1" colspan="1">Parameter Name</th>
            <th class="text-left" rowspan="1" colspan="1">YANG Type</th>
            <th class="text-left" rowspan="1" colspan="1">CBOR Key</th>
            <th class="text-left" rowspan="1" colspan="1">CBOR Major Type &amp; Information</th>
            <th class="text-left" rowspan="1" colspan="1">JSON Type</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1"> ietf-dots-signal-channel:mitigation-scope</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">1</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">scope</td>
            <td class="text-left" rowspan="1" colspan="1">list</td>
            <td class="text-left" rowspan="1" colspan="1">2</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">cdid</td>
            <td class="text-left" rowspan="1" colspan="1">string</td>
            <td class="text-left" rowspan="1" colspan="1">3</td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">cuid</td>
            <td class="text-left" rowspan="1" colspan="1">string</td>
            <td class="text-left" rowspan="1" colspan="1">4</td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">mid</td>
            <td class="text-left" rowspan="1" colspan="1">uint32</td>
            <td class="text-left" rowspan="1" colspan="1">5</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">target-prefix</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">6</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">inet:ip-prefix</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">target-port-range</td>
            <td class="text-left" rowspan="1" colspan="1">list</td>
            <td class="text-left" rowspan="1" colspan="1">7</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">lower-port</td>
            <td class="text-left" rowspan="1" colspan="1">inet:port-number</td>
            <td class="text-left" rowspan="1" colspan="1">8</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">upper-port</td>
            <td class="text-left" rowspan="1" colspan="1">inet:port-number</td>
            <td class="text-left" rowspan="1" colspan="1">9</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">target-protocol</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">10</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">uint8</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">target-fqdn</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">11</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">inet:domain-name</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">target-uri</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">12</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">inet:uri</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">alias-name</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">13</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">string</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">lifetime</td>
            <td class="text-left" rowspan="2" colspan="1">union</td>
            <td class="text-left" rowspan="2" colspan="1">14</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">1 negative</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">mitigation-start</td>
            <td class="text-left" rowspan="1" colspan="1">uint64</td>
            <td class="text-left" rowspan="1" colspan="1">15</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">status</td>
            <td class="text-left" rowspan="1" colspan="1">enumeration</td>
            <td class="text-left" rowspan="1" colspan="1">16</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">conflict-information</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">17</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">conflict-status</td>
            <td class="text-left" rowspan="1" colspan="1">enumeration</td>
            <td class="text-left" rowspan="1" colspan="1">18</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">conflict-cause</td>
            <td class="text-left" rowspan="1" colspan="1">enumeration</td>
            <td class="text-left" rowspan="1" colspan="1">19</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">retry-timer</td>
            <td class="text-left" rowspan="1" colspan="1">uint32</td>
            <td class="text-left" rowspan="1" colspan="1">20</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">conflict-scope</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">21</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">acl-list</td>
            <td class="text-left" rowspan="1" colspan="1">list</td>
            <td class="text-left" rowspan="1" colspan="1">22</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">acl-name</td>
            <td class="text-left" rowspan="1" colspan="1">leafref</td>
            <td class="text-left" rowspan="1" colspan="1">23</td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">acl-type</td>
            <td class="text-left" rowspan="1" colspan="1">leafref</td>
            <td class="text-left" rowspan="1" colspan="1">24</td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">bytes-dropped</td>
            <td class="text-left" rowspan="1" colspan="1">yang:zero-based-counter64</td>
            <td class="text-left" rowspan="1" colspan="1">25</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">bps-dropped</td>
            <td class="text-left" rowspan="1" colspan="1">yang:gauge64</td>
            <td class="text-left" rowspan="1" colspan="1">26</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">pkts-dropped</td>
            <td class="text-left" rowspan="1" colspan="1">yang:zero-based-counter64</td>
            <td class="text-left" rowspan="1" colspan="1">27</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">pps-dropped</td>
            <td class="text-left" rowspan="1" colspan="1">yang:gauge64</td>
            <td class="text-left" rowspan="1" colspan="1">28</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">attack-status</td>
            <td class="text-left" rowspan="1" colspan="1">enumeration</td>
            <td class="text-left" rowspan="1" colspan="1">29</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ietf-dots-signal-channel:signal-config</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">30</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">sid</td>
            <td class="text-left" rowspan="1" colspan="1">uint32</td>
            <td class="text-left" rowspan="1" colspan="1">31</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">mitigating-config</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">32</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">heartbeat-interval</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">33</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">max-value</td>
            <td class="text-left" rowspan="1" colspan="1">uint16</td>
            <td class="text-left" rowspan="1" colspan="1">34</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">min-value</td>
            <td class="text-left" rowspan="1" colspan="1">uint16</td>
            <td class="text-left" rowspan="1" colspan="1">35</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">current-value</td>
            <td class="text-left" rowspan="1" colspan="1">uint16</td>
            <td class="text-left" rowspan="1" colspan="1">36</td>
            <td class="text-left" rowspan="1" colspan="1">0 unsigned</td>
            <td class="text-left" rowspan="1" colspan="1">Number</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">missing-hb-allowed</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">37</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">max-retransmit</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">38</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ack-timeout</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">39</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ack-random-factor</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">40</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">max-value-decimal</td>
            <td class="text-left" rowspan="1" colspan="1">decimal64</td>
            <td class="text-left" rowspan="1" colspan="1">41</td>
            <td class="text-left" rowspan="1" colspan="1">6 tag 4  [-2, integer]</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">min-value-decimal</td>
            <td class="text-left" rowspan="1" colspan="1">decimal64</td>
            <td class="text-left" rowspan="1" colspan="1">42</td>
            <td class="text-left" rowspan="1" colspan="1">6 tag 4 [-2, integer]</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">current-value-decimal</td>
            <td class="text-left" rowspan="1" colspan="1">decimal64</td>
            <td class="text-left" rowspan="1" colspan="1">43</td>
            <td class="text-left" rowspan="1" colspan="1">6 tag 4 [-2, integer]</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">idle-config</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">44</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">trigger-mitigation</td>
            <td class="text-left" rowspan="2" colspan="1">boolean</td>
            <td class="text-left" rowspan="2" colspan="1">45</td>
            <td class="text-left" rowspan="1" colspan="1">7 bits 20</td>
            <td class="text-left" rowspan="1" colspan="1">False</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">7 bits 21</td>
            <td class="text-left" rowspan="1" colspan="1">True</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ietf-dots-signal-channel:redirected-signal</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">46</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">alt-server</td>
            <td class="text-left" rowspan="1" colspan="1">inet:domain-name</td>
            <td class="text-left" rowspan="1" colspan="1">47</td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">alt-server-record</td>
            <td class="text-left" rowspan="1" colspan="1">leaf-list</td>
            <td class="text-left" rowspan="1" colspan="1">48</td>
            <td class="text-left" rowspan="1" colspan="1">4 array</td>
            <td class="text-left" rowspan="1" colspan="1">Array</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">inet:ip-address</td>
            <td class="text-left" rowspan="1" colspan="1"></td>
            <td class="text-left" rowspan="1" colspan="1">3 text string</td>
            <td class="text-left" rowspan="1" colspan="1">String</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ietf-dots-signal-channel:heartbeat</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">49</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">probing-rate</td>
            <td class="text-left" rowspan="1" colspan="1">container</td>
            <td class="text-left" rowspan="1" colspan="1">50</td>
            <td class="text-left" rowspan="1" colspan="1">5 map</td>
            <td class="text-left" rowspan="1" colspan="1">Object</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="2" colspan="1">peer-hb-status</td>
            <td class="text-left" rowspan="2" colspan="1">boolean</td>
            <td class="text-left" rowspan="2" colspan="1">51</td>
            <td class="text-left" rowspan="1" colspan="1">7 bits 20</td>
            <td class="text-left" rowspan="1" colspan="1">False</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">7 bits 21</td>
            <td class="text-left" rowspan="1" colspan="1">True</td>
          </tr>
        </tbody>
      </table>
</div>
</section>
</div>
<div id="profile">
<section id="section-7">
      <h2 id="name-dtls-protocol-profile-and-p">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-dtls-protocol-profile-and-p" class="section-name selfRef">(D)TLS Protocol Profile and Performance Considerations</a>
      </h2>
<section id="section-7.1">
        <h3 id="name-dtls-protocol-profile">
<a href="#section-7.1" class="section-number selfRef">7.1. </a><a href="#name-dtls-protocol-profile" class="section-name selfRef">(D)TLS Protocol Profile</a>
        </h3>
<p id="section-7.1-1">This section defines the (D)TLS protocol profile of DOTS signal
        channel over (D)TLS and DOTS data channel over TLS.<a href="#section-7.1-1" class="pilcrow">¶</a></p>
<p id="section-7.1-2">There are known attacks on (D)TLS, such as man-in-the-middle and
        protocol downgrade attacks. These are general attacks on (D)TLS and,
        as such, they are not specific to DOTS over (D)TLS; refer to the
        (D)TLS RFCs for discussion of these security issues. DOTS agents <span class="bcp14">MUST</span>
        adhere to the (D)TLS implementation recommendations and security
        considerations of <span>[<a href="#RFC7525" class="xref">RFC7525</a>]</span> except with respect
        to (D)TLS version. Because DOTS signal channel encryption relying upon
        (D)TLS is virtually a greenfield deployment, DOTS agents <span class="bcp14">MUST</span>
        implement only (D)TLS 1.2 or later.<a href="#section-7.1-2" class="pilcrow">¶</a></p>
<p id="section-7.1-3">When a DOTS client is configured with a domain name of the DOTS
        server, and it connects to its configured DOTS server, the server may
        present it with a PKIX certificate. In order to ensure proper
        authentication, a DOTS client <span class="bcp14">MUST</span> verify the entire
 certification
        path per <span>[<a href="#RFC5280" class="xref">RFC5280</a>]</span>. Additionally, the
 DOTS client
        <span class="bcp14">MUST</span> use <span>[<a href="#RFC6125" class="xref">RFC6125</a>]</span>
 validation techniques to
        compare the domain name with the certificate provided. Certification
        authorities that issue DOTS server certificates <span class="bcp14">SHOULD</span>
 support the
        DNS-ID and SRV-ID identifier types. DOTS servers <span class="bcp14">SHOULD</span>
 prefer the use
        of DNS-ID and SRV-ID over Common Name ID (CN-ID) identifier types in
 certificate
        requests (as described in <span><a href="https://www.rfc-editor.org/rfc/rfc6125#section-2.3" class="relref">Section 2.3</a> of [<a href="#RFC6125" class="xref">RFC6125</a>]</span>),
 and the wildcard character '*' <span class="bcp14">SHOULD NOT</span>
        be included in the presented identifier. DOTS doesn't use URI-IDs for
        server identity verification.<a href="#section-7.1-3" class="pilcrow">¶</a></p>
<p id="section-7.1-4">A key challenge to deploying DOTS is the provisioning of DOTS
        clients, including the distribution of keying material to DOTS clients
        to enable the required mutual authentication of DOTS agents.
        Enrollment over Secure Transport (EST) <span>[<a href="#RFC7030" class="xref">RFC7030</a>]</span>
        defines a method of certificate enrollment by which domains operating
        DOTS servers may provide DOTS clients with all the necessary
        cryptographic keying material, including a private key and a
        certificate, to authenticate themselves. One deployment option is to
        have DOTS clients behave as EST clients for certificate enrollment
        from an EST server provisioned by the mitigation provider. This
        document does not specify which EST or other mechanism the DOTS client
        uses to achieve initial enrollment.<a href="#section-7.1-4" class="pilcrow">¶</a></p>
<p id="section-7.1-5">The Server Name Indication (SNI) extension <span>[<a href="#RFC6066" class="xref">RFC6066</a>]</span> defines a mechanism for a client to tell a
        (D)TLS server the name of the server it wants to contact. This is a
        useful extension for hosting environments where multiple virtual
        servers are reachable over a single IP address. The DOTS client may or
        may not know if it is interacting with a DOTS server in a virtual
        server-hosting environment, so the DOTS client <span class="bcp14">SHOULD</span> include the DOTS
        server FQDN in the SNI extension.<a href="#section-7.1-5" class="pilcrow">¶</a></p>
<p id="section-7.1-6">Implementations compliant with this profile <span class="bcp14">MUST</span> implement all of
        the following items:<a href="#section-7.1-6" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-7.1-7.1">DTLS record replay detection (<span><a href="https://www.rfc-editor.org/rfc/rfc6347#section-3.3" class="relref">Section 3.3</a> of [<a href="#RFC6347" class="xref">RFC6347</a>]</span>) or an equivalent mechanism to protect
            against replay attacks.<a href="#section-7.1-7.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-7.1-7.2">DTLS session resumption without server-side state to resume
            session and convey the DOTS signal.<a href="#section-7.1-7.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-7.1-7.3">At least one of raw public keys <span>[<a href="#RFC7250" class="xref">RFC7250</a>]</span>
            or PSK handshake <span>[<a href="#RFC4279" class="xref">RFC4279</a>]</span> with
     (EC)DHE key
            exchange. This reduces the size of the ServerHello. Also, this can
            be used by DOTS agents that cannot obtain certificates.<a href="#section-7.1-7.3" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-7.1-8">Implementations compliant with this profile <span class="bcp14">SHOULD</span>
 implement all of
        the following items to reduce the delay required to deliver a DOTS
        signal channel message:<a href="#section-7.1-8" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-7.1-9.1">TLS False Start <span>[<a href="#RFC7918" class="xref">RFC7918</a>]</span>, which reduces
            round trips by allowing the TLS client's second flight of messages
            (ChangeCipherSpec) to also contain the DOTS signal. TLS False
            Start is formally defined for use with TLS, but the same technique
            is applicable to DTLS as well.<a href="#section-7.1-9.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-7.1-9.2">Cached Information Extension <span>[<a href="#RFC7924" class="xref">RFC7924</a>]</span>,
            which avoids transmitting the server's certificate and certificate
            chain if the client has cached that information from a previous
            TLS handshake.<a href="#section-7.1-9.2" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-7.1-10">Compared to UDP, DOTS signal channel over TCP requires an
        additional round-trip time (RTT) of latency to establish a TCP
        connection. DOTS implementations are encouraged to implement TCP Fast
        Open <span>[<a href="#RFC7413" class="xref">RFC7413</a>]</span> to eliminate that RTT.<a href="#section-7.1-10" class="pilcrow">¶</a></p>
</section>
<div id="DTLS">
<section id="section-7.2">
        <h3 id="name-dtls-13-considerations">
<a href="#section-7.2" class="section-number selfRef">7.2. </a><a href="#name-dtls-13-considerations" class="section-name selfRef">(D)TLS 1.3 Considerations</a>
        </h3>
<p id="section-7.2-1">TLS 1.3 provides useful latency improvements for connection
        establishment over TLS 1.2. The DTLS 1.3 protocol <span>[<a href="#I-D.ietf-tls-dtls13" class="xref">TLS-DTLS13</a>]</span> is based upon the TLS 1.3
        protocol and provides equivalent security guarantees. (D)TLS 1.3
        provides two basic handshake modes the DOTS signal channel can take
        advantage of:<a href="#section-7.2-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-7.2-2.1">A full handshake mode in which a DOTS client can send a DOTS
            mitigation request message after one round trip and the DOTS
            server immediately responds with a DOTS mitigation response. This
            assumes no packet loss is experienced.<a href="#section-7.2-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-7.2-2.2">0-RTT mode in which the DOTS client can authenticate itself and
            send DOTS mitigation request messages in the first message, thus
            reducing handshake latency. 0-RTT only works if the DOTS client
            has previously communicated with that DOTS server, which is very
            likely with the DOTS signal channel.<a href="#section-7.2-2.2" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-7.2-3">The DOTS client has to establish a (D)TLS session with the DOTS
        server during 'idle' time and share a PSK.<a href="#section-7.2-3" class="pilcrow">¶</a></p>
<p id="section-7.2-4">During a DDoS attack, the DOTS client can use the (D)TLS session to
        convey the DOTS mitigation request message and, if there is no
        response from the server after multiple retries, the DOTS client can
        resume the (D)TLS session in 0-RTT mode using PSK.<a href="#section-7.2-4" class="pilcrow">¶</a></p>
<p id="section-7.2-5">DOTS servers that support (D)TLS 1.3 <span class="bcp14">MAY</span> allow DOTS clients to send
        early data (0-RTT). DOTS clients <span class="bcp14">MUST NOT</span> send "CoAP Ping" as early
        data; such messages <span class="bcp14">MUST</span> be rejected by DOTS servers.
        <span><a href="https://www.rfc-editor.org/rfc/rfc8446#section-8" class="relref">Section 8</a> of [<a href="#RFC8446" class="xref">RFC8446</a>]</span> discusses some mechanisms to
 implement
        in order to limit the impact of replay attacks on 0-RTT data. If the
        DOTS server accepts 0-RTT, it <span class="bcp14">MUST</span> implement one of these mechanisms
        to prevent replay at the TLS layer. A DOTS server can reject 0-RTT by
        sending a TLS HelloRetryRequest.<a href="#section-7.2-5" class="pilcrow">¶</a></p>
<p id="section-7.2-6">The DOTS signal channel messages sent as early data by the DOTS
        client are idempotent requests. As a reminder, the Message ID 
        (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-3" class="relref">Section 3</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>) is changed each time a new CoAP
        request is sent, and the Token (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.3.1" class="relref">Section 5.3.1</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>) is randomized in each CoAP request. The DOTS
        server(s) <span class="bcp14">MUST</span> use the Message ID and the Token in the DOTS signal
        channel message to detect replay of early data at the application
        layer and accept 0-RTT data at most once from the same DOTS client.
        This anti-replay defense requires sharing the Message ID and the Token
        in the 0-RTT data between DOTS servers in the DOTS server domain. DOTS
        servers do not rely on transport coordinates to identify DOTS peers.
        As specified in <a href="#post" class="xref">Section 4.4.1</a>, DOTS servers couple the
        DOTS signal channel sessions using the DOTS client identity and
        optionally the 'cdid' parameter value. Furthermore, the 'mid' value is
        monotonically increased by the DOTS client for each mitigation
        request, thus attackers that replay mitigation requests with lower
        numeric 'mid' values and overlapping scopes with mitigation requests
        having higher numeric 'mid' values will be rejected systematically by
        the DOTS server. Likewise, the 'sid' value is monotonically increased
        by the DOTS client for each configuration request (<a href="#convey" class="xref">Section 4.5.2</a>); attackers replaying configuration requests
        with lower numeric 'sid' values will be rejected by the DOTS server if
        it maintains a higher numeric 'sid' value for this DOTS client.<a href="#section-7.2-6" class="pilcrow">¶</a></p>
<p id="section-7.2-7">Owing to the aforementioned protections, all DOTS signal channel
        requests are safe to transmit in TLS 1.3 as early data. Refer to <span>[<a href="#I-D.boucadair-dots-earlydata" class="xref">DOTS-EARLYDATA</a>]</span> for more details.<a href="#section-7.2-7" class="pilcrow">¶</a></p>
<p id="section-7.2-8">A simplified TLS 1.3 handshake with 0-RTT DOTS mitigation request
        message exchange is shown in <a href="#Figure24" class="xref">Figure 29</a>.<a href="#section-7.2-8" class="pilcrow">¶</a></p>
<span id="name-a-simplified-tls-13-handsha"></span><div id="Figure24">
<figure id="figure-29">
          <div class="artwork art-text alignLeft" id="section-7.2-9.1">
<pre>
    DOTS Client                                    DOTS Server

    ClientHello
    (0-RTT DOTS signal message)
                              --------&gt;
                                                    ServerHello
                                          {EncryptedExtensions}
                                                     {Finished}
                              &lt;--------   [DOTS signal message]
    (end_of_early_data)
    {Finished}                --------&gt;
    [DOTS signal message]     &lt;-------&gt;   [DOTS signal message]

Note that:
    () Indicates messages protected 0-RTT keys
    {} Indicates messages protected using handshake keys
    [] Indicates messages protected using 1-RTT keys
</pre>
</div>
<figcaption><a href="#figure-29" class="selfRef">Figure 29</a>:
<a href="#name-a-simplified-tls-13-handsha" class="selfRef">A Simplified TLS 1.3 Handshake with 0-RTT</a>
          </figcaption></figure>
</div>
</section>
</div>
<div id="mtu">
<section id="section-7.3">
        <h3 id="name-dtls-mtu-and-fragmentation">
<a href="#section-7.3" class="section-number selfRef">7.3. </a><a href="#name-dtls-mtu-and-fragmentation" class="section-name selfRef">DTLS MTU and Fragmentation</a>
        </h3>
<p id="section-7.3-1">To avoid DOTS signal message fragmentation and the subsequent
        decreased probability of message delivery, the DLTS records need to
        fit within a single datagram <span>[<a href="#RFC6347" class="xref">RFC6347</a>]</span>. DTLS
        handles fragmentation and reassembly only for handshake messages and
        not for the application data (<span><a href="https://www.rfc-editor.org/rfc/rfc6347#section-4.1.1" class="relref">Section 4.1.1</a> of [<a href="#RFC6347" class="xref">RFC6347</a>]</span>). If the Path MTU (PMTU) cannot be
        discovered, DOTS agents <span class="bcp14">MUST</span> assume a PMTU of 1280 bytes, as IPv6
        requires that every link in the Internet have an MTU of 1280 octets or
        greater, as specified in <span>[<a href="#RFC8200" class="xref">RFC8200</a>]</span>. If IPv4
        support on legacy or otherwise unusual networks is a consideration and
        the PMTU is unknown, DOTS implementations <span class="bcp14">MAY</span> assume a PMTU of 576
        bytes for IPv4 datagrams (see <span><a href="https://www.rfc-editor.org/rfc/rfc1122#section-3.3.3" class="relref">Section 3.3.3</a> of [<a href="#RFC1122" class="xref">RFC1122</a>]</span>).<a href="#section-7.3-1" class="pilcrow">¶</a></p>
<p id="section-7.3-2">The DOTS client must consider the amount of record expansion
        expected by the DTLS processing when calculating the size of the CoAP
        message that fits within the PMTU. The PMTU <span class="bcp14">MUST</span> be greater than or equal
        to [CoAP message size + DTLS 1.2 overhead of 13 octets +
        authentication overhead of the negotiated DTLS cipher suite + block
        padding] (<span><a href="https://www.rfc-editor.org/rfc/rfc6347#section-4.1.1.1" class="relref">Section 4.1.1.1</a> of [<a href="#RFC6347" class="xref">RFC6347</a>]</span>). If the
        total request size exceeds the PMTU, then the DOTS client <span class="bcp14">MUST</span> split
        the DOTS signal into separate messages; for example, the list of
        addresses in the 'target-prefix' parameter could be split into
        multiple lists and each list conveyed in a new PUT request.<a href="#section-7.3-2" class="pilcrow">¶</a></p>
<aside id="section-7.3-3">
          <p id="section-7.3-3.1">Implementation Note: DOTS choice of message size parameters
        works well with IPv6 and with most of today's IPv4 paths.
        However, with IPv4, it is harder to safely make sure that there
        is no IP fragmentation.  If the IPv4 PMTU is unknown,
        implementations may want to limit themselves to more
        conservative IPv4 datagram sizes, such as 576 bytes, per
        <span>[<a href="#RFC0791" class="xref">RFC0791</a>]</span>.<a href="#section-7.3-3.1" class="pilcrow">¶</a></p>
</aside>
</section>
</div>
</section>
</div>
<div id="mutauth">
<section id="section-8">
      <h2 id="name-mutual-authentication-of-do">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-mutual-authentication-of-do" class="section-name selfRef">Mutual Authentication of DOTS Agents &amp; Authorization of DOTS Clients</a>
      </h2>
<p id="section-8-1">(D)TLS based upon client certificates can be used for mutual
      authentication between DOTS agents. If, for example, a DOTS gateway is
      involved, DOTS clients and DOTS gateways must perform mutual
      authentication; only authorized DOTS clients are allowed to send DOTS
      signals to a DOTS gateway. The DOTS gateway and the DOTS server must
      perform mutual authentication; a DOTS server only allows DOTS signal
      channel messages from an authorized DOTS gateway, thereby creating a
      two-link chain of transitive authentication between the DOTS client and
      the DOTS server.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">The DOTS server should support certificate-based client
      authentication. The DOTS client should respond to the DOTS server's TLS
      CertificateRequest message with the PKIX certificate held by the DOTS
      client. DOTS client certificate validation must be performed per <span>[<a href="#RFC5280" class="xref">RFC5280</a>]</span>, and the DOTS client certificate must conform
      to the <span>[<a href="#RFC5280" class="xref">RFC5280</a>]</span> certificate profile. If a DOTS
      client does not support TLS client certificate authentication, it must
      support client authentication based on pre-shared key or raw public
      key.<a href="#section-8-2" class="pilcrow">¶</a></p>
<span id="name-example-of-authentication-a"></span><div id="Figure12">
<figure id="figure-30">
        <div class="artwork art-text alignCenter" id="section-8-3.1">
<pre>
+---------------------------------------------+
|       example.com domain       +---------+  |
|                                | AAA     |  |
| +---------------+              | Server  |  |
| | Application   |              +------+--+  |
| | server        +&lt;---------------+    ^     |
| | (DOTS client) |                |    |     |
| +---------------+                |    |     |
|                                  V    V     |   example.net domain
|                            +-----+----+--+  |    +---------------+
| +--------------+           |             |  |    |               |
| |   Guest      +&lt;----x----&gt;+    DOTS     +&lt;-----&gt;+    DOTS       |
| | (DOTS client)|           |    gateway  |  |    |    server     |
| +--------------+           |             |  |    |               |
|                            +----+--------+  |    +---------------+
|                                 ^           |
|                                 |           |
| +----------------+              |           |
| | DDoS detector  |              |           |
| | (DOTS client)  +&lt;-------------+           |
| +----------------+                          |
+---------------------------------------------+
</pre>
</div>
<figcaption><a href="#figure-30" class="selfRef">Figure 30</a>:
<a href="#name-example-of-authentication-a" class="selfRef">Example of Authentication and Authorization of DOTS Agents</a>
        </figcaption></figure>
</div>
<p id="section-8-4">In the example depicted in <a href="#Figure12" class="xref">Figure 30</a>, the DOTS
      gateway and DOTS clients within the 'example.com' domain proceed with
      mutual authentication. After the DOTS gateway validates the identity of
      a DOTS client, it communicates with the Authentication, Authorization, and
      Accounting (AAA) server in the 'example.com'
      domain to determine if the DOTS client is authorized to request DDoS
      mitigation. If the DOTS client is not authorized, a 4.01 (Unauthorized)
      is returned in the response to the DOTS client. In this example, the
      DOTS gateway only allows the application server and DDoS attack detector
      to request DDoS mitigation, but does not permit the user of type 'guest'
      to request DDoS mitigation.<a href="#section-8-4" class="pilcrow">¶</a></p>
<p id="section-8-5">Also, DOTS gateways and servers located in different domains must
      perform mutual authentication (e.g., using certificates). A DOTS server
      will only allow a DOTS gateway with a certificate for a particular
      domain to request mitigation for that domain. In reference to <a href="#Figure12" class="xref">Figure 30</a>, the DOTS server only allows the DOTS gateway
      to request mitigation for the 'example.com' domain and not for other
      domains.<a href="#section-8-5" class="pilcrow">¶</a></p>
</section>
</div>
<div id="errors">
<section id="section-9">
      <h2 id="name-error-handling">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-error-handling" class="section-name selfRef">Error Handling</a>
      </h2>
<p id="section-9-1">This section is a summary of the Error Code responses that can be
      returned by a DOTS server. These error responses must contain a CoAP
      4.xx or 5.xx Response Code.<a href="#section-9-1" class="pilcrow">¶</a></p>
<p id="section-9-2">In general, there may be an additional plain text diagnostic payload
      (<span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-5.5.2" class="relref">Section 5.5.2</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>) to help
      troubleshooting in the body of the response unless detailed
      otherwise.<a href="#section-9-2" class="pilcrow">¶</a></p>
<p id="section-9-3">Errors returned by a DOTS server can be broken into two categories:
      those associated with CoAP itself and those generated during the
      validation of the provided data by the DOTS server.<a href="#section-9-3" class="pilcrow">¶</a></p>
<p id="section-9-4">The following is a list of common CoAP errors that are implemented by DOTS
      servers. This list is not exhaustive; other errors defined by CoAP and
      associated RFCs may be applicable.<a href="#section-9-4" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-9-5">
        <dt id="section-9-5.1">4.00 (Bad Request)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.2">is returned by the DOTS server when
          the DOTS client has sent a request that violates the DOTS protocol
          (<a href="#sig" class="xref">Section 4</a>).<a href="#section-9-5.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.3">4.01 (Unauthorized)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.4">is returned by the DOTS server
          when the DOTS client is not authorized to access the DOTS server
          (<a href="#sig" class="xref">Section 4</a>).<a href="#section-9-5.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.5">4.02 (Bad Option)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.6">is returned by the DOTS server when
          one or more CoAP options are unknown or malformed by the CoAP layer
          <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>.<a href="#section-9-5.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.7">4.04 (Not Found)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.8">is returned by the DOTS server when
          the DOTS client is requesting a 'mid' or 'sid' that is not valid
          (<a href="#sig" class="xref">Section 4</a>).<a href="#section-9-5.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.9">4.05 (Method Not Allowed)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.10">is returned by the DOTS
          server when the DOTS client is requesting a resource by a method
          (e.g., GET) that is not supported by the DOTS server <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span>.<a href="#section-9-5.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.11">4.08 (Request Entity Incomplete)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.12">is returned by the
          DOTS server if one or multiple blocks of a block transfer request is
          missing <span>[<a href="#RFC7959" class="xref">RFC7959</a>]</span>.<a href="#section-9-5.12" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.13">4.09 (Conflict)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.14">is returned by the DOTS server if the
          DOTS server detects that a request conflicts with a previous
          request. The response body is formatted using
          "application/dots+cbor" and contains the "conflict-clause" (<a href="#pro-mit-req" class="xref">Section 4.4.1.3</a>).<a href="#section-9-5.14" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.15">4.13 (Request Entity Too Large)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.16">may be returned by the
          DOTS server during a block transfer request <span>[<a href="#RFC7959" class="xref">RFC7959</a>]</span>.<a href="#section-9-5.16" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.17">4.15 (Unsupported Content-Format)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.18">is returned by the
          DOTS server when the Content-Format is used but the request is not
          formatted as "application/dots+cbor" (<a href="#sig" class="xref">Section 4</a>).<a href="#section-9-5.18" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.19">4.22 (Unprocessable Entity)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.20">is returned by the DOTS
          server when one or more session configuration parameters are not
          valid (<a href="#sigconfig" class="xref">Section 4.5</a>).<a href="#section-9-5.20" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.21">5.03 (Service Unavailable)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.22">is returned by the DOTS
          server if the DOTS server is unable to handle the request (<a href="#sig" class="xref">Section 4</a>). An example is the DOTS server needs to
          redirect the DOTS client to use an alternate DOTS server (<a href="#redirect" class="xref">Section 4.6</a>). The response body is formatted using
          "application/dots+cbor" and contains how to handle the 5.03
          Response Code.<a href="#section-9-5.22" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-9-5.23">5.08 (Hop Limit Reached)</dt>
        <dd style="margin-left: 1.5em" id="section-9-5.24">is returned by the DOTS
          server if there is a data path loop through upstream DOTS gateways.
          The response body is formatted using plain text and contains a list
          of servers that are in the data path loop <span>[<a href="#RFC8768" class="xref">RFC8768</a>]</span>.<a href="#section-9-5.24" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
</section>
</div>
<div id="IANA">
<section id="section-10">
      <h2 id="name-iana-considerations">
<a href="#section-10" class="section-number selfRef">10. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<div id="port">
<section id="section-10.1">
        <h3 id="name-dots-signal-channel-udp-and">
<a href="#section-10.1" class="section-number selfRef">10.1. </a><a href="#name-dots-signal-channel-udp-and" class="section-name selfRef">DOTS Signal Channel UDP and TCP Port Number</a>
        </h3>
<p id="section-10.1-1">IANA has assigned the port number 4646 (the ASCII decimal value for
        ".." (DOTS)) to the DOTS signal channel protocol for both UDP and TCP
        from the "Service Name and Transport Protocol Port Number Registry"
        available at <span>&lt;<a href="https://www.iana.org/assignments/service-names-port-numbers/">https://www.iana.org/assignments/service-names-port-numbers/</a>&gt;</span>.<a href="#section-10.1-1" class="pilcrow">¶</a></p>
<p id="section-10.1-2">IANA has updated these entries to refer to this document and updated the Description as described below:<a href="#section-10.1-2" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.1-3">
          <dt id="section-10.1-3.1">Service Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.2">dots-signal<a href="#section-10.1-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.3">Port Number:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.4">4646<a href="#section-10.1-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.5">Transport Protocol:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.6">TCP<a href="#section-10.1-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.7">Description:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.8">Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Protocol. The service name is used to construct the SRV service names "_dots-signal._udp" and "_dots-signal._tcp" for discovering DOTS servers used to establish DOTS signal channel.<a href="#section-10.1-3.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.9">Assignee:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.10">IESG<a href="#section-10.1-3.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.11">Contact:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.12">IETF Chair<a href="#section-10.1-3.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.13">Registration Date:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.14">2020-01-16<a href="#section-10.1-3.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.15">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.16">[RFC8973][RFC9132]<a href="#section-10.1-3.16" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.1-4">
          <dt id="section-10.1-4.1">Service Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.2">dots-signal<a href="#section-10.1-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.3">Port Number:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.4">4646<a href="#section-10.1-4.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.5">Transport Protocol:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.6">UDP<a href="#section-10.1-4.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.7">Description:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.8">Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Protocol. The service name is used to construct the SRV service names "_dots-signal._udp" and "_dots-signal._tcp" for discovering DOTS servers used to establish DOTS signal channel.<a href="#section-10.1-4.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.9">Assignee:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.10">IESG<a href="#section-10.1-4.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.11">Contact:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.12">IETF Chair<a href="#section-10.1-4.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.13">Registration Date:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.14">2020-01-16<a href="#section-10.1-4.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.15">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.16">[RFC8973][RFC9132]<a href="#section-10.1-4.16" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="uri">
<section id="section-10.2">
        <h3 id="name-well-known-dots-uri">
<a href="#section-10.2" class="section-number selfRef">10.2. </a><a href="#name-well-known-dots-uri" class="section-name selfRef">Well-Known 'dots' URI</a>
        </h3>
<p id="section-10.2-1">IANA has updated the 'dots' well-known URI (<a href="#table6" class="xref">Table 6</a>)
        entry in the "Well-Known URIs" registry <span>[<a href="#URI" class="xref">URI</a>]</span> as
        follows:<a href="#section-10.2-1" class="pilcrow">¶</a></p>
<span id="name-dots-well-known-uri"></span><div id="table6">
<table class="center" id="table-6">
          <caption>
<a href="#table-6" class="selfRef">Table 6</a>:
<a href="#name-dots-well-known-uri" class="selfRef">'dots' Well-Known URI</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">URI Suffix</th>
              <th class="text-left" rowspan="1" colspan="1">Change Controller</th>
              <th class="text-left" rowspan="1" colspan="1">Reference</th>
              <th class="text-left" rowspan="1" colspan="1">Status</th>
              <th class="text-left" rowspan="1" colspan="1">Related information</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">dots</td>
              <td class="text-left" rowspan="1" colspan="1">IETF</td>
              <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              <td class="text-left" rowspan="1" colspan="1">permanent</td>
              <td class="text-left" rowspan="1" colspan="1">None</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
<div id="MediaReg">
<section id="section-10.3">
        <h3 id="name-media-type-registration">
<a href="#section-10.3" class="section-number selfRef">10.3. </a><a href="#name-media-type-registration" class="section-name selfRef">Media Type Registration</a>
        </h3>
<p id="section-10.3-1">IANA has updated the "application/dots+cbor" media type
        in the "Media Types" registry <span>[<a href="#IANA-MediaTypes" class="xref">IANA-MediaTypes</a>]</span>
        in the manner described in <span>[<a href="#RFC6838" class="xref">RFC6838</a>]</span>, which can
        be used to indicate that the content is a DOTS signal channel
        object:<a href="#section-10.3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-10.3-2">
          <dt id="section-10.3-2.1">Type name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.2">application<a href="#section-10.3-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.3">Subtype name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.4">dots+cbor<a href="#section-10.3-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.5">Required parameters:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.6">N/A<a href="#section-10.3-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.7">Optional parameters:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.8">N/A<a href="#section-10.3-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.9">Encoding considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.10">binary<a href="#section-10.3-2.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.11">Security considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.12">See the Security Considerations section of
   RFC 9132.<a href="#section-10.3-2.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.13">Interoperability considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.14">N/A<a href="#section-10.3-2.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.15">Published specification:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.16">RFC 9132<a href="#section-10.3-2.16" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.17">Applications that use this media type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.18">DOTS agents sending DOTS
   messages over CoAP over (D)TLS.<a href="#section-10.3-2.18" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.19">Fragment identifier considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.20">N/A<a href="#section-10.3-2.20" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlNewline" id="section-10.3-3">
          <dt id="section-10.3-3.1">Additional information:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-3.2">
            <span class="break"></span><dl class="dlParallel dlCompact" id="section-10.3-3.2.1">
              <dt id="section-10.3-3.2.1.1">Deprecated alias names for this type:</dt>
              <dd style="margin-left: 1.5em" id="section-10.3-3.2.1.2">N/A<a href="#section-10.3-3.2.1.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.3-3.2.1.3">Magic number(s):</dt>
              <dd style="margin-left: 1.5em" id="section-10.3-3.2.1.4">N/A<a href="#section-10.3-3.2.1.4" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.3-3.2.1.5">File extension(s):</dt>
              <dd style="margin-left: 1.5em" id="section-10.3-3.2.1.6">N/A<a href="#section-10.3-3.2.1.6" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.3-3.2.1.7">Macintosh file type code(s):</dt>
              <dd style="margin-left: 1.5em" id="section-10.3-3.2.1.8">N/A<a href="#section-10.3-3.2.1.8" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlParallel" id="section-10.3-4">
          <dt id="section-10.3-4.1">Person &amp; email address to contact for further information:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.2">
            <br>IESG, iesg@ietf.org<a href="#section-10.3-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-4.3">Intended usage:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.4">COMMON<a href="#section-10.3-4.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-4.5">Restrictions on usage:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.6">none<a href="#section-10.3-4.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-4.7">Author:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.8">See Authors' Addresses section.<a href="#section-10.3-4.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-4.9">Change controller:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.10">IESG<a href="#section-10.3-4.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-4.11">Provisional registration?</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-4.12">No<a href="#section-10.3-4.12" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="IANACoAPContentFormatRegistration">
<section id="section-10.4">
        <h3 id="name-coap-content-formats-regist">
<a href="#section-10.4" class="section-number selfRef">10.4. </a><a href="#name-coap-content-formats-regist" class="section-name selfRef">CoAP Content-Formats Registration</a>
        </h3>
<p id="section-10.4-1">IANA has updated the 
        "application/dots+cbor" media type in the "CoAP Content-Formats"
        registry <span>[<a href="#IANA-CoAP-Content-Formats" class="xref">IANA-CoAP-Content-Formats</a>]</span> as follows:<a href="#section-10.4-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.4-2">
          <dt id="section-10.4-2.1">Media Type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.4-2.2">application/dots+cbor<a href="#section-10.4-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.4-2.3">Encoding:</dt>
          <dd style="margin-left: 1.5em" id="section-10.4-2.4">-<a href="#section-10.4-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.4-2.5">ID:</dt>
          <dd style="margin-left: 1.5em" id="section-10.4-2.6">271<a href="#section-10.4-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.4-2.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.4-2.8">[RFC9132]<a href="#section-10.4-2.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="IANACBORTagAssignment">
<section id="section-10.5">
        <h3 id="name-cbor-tag-registration">
<a href="#section-10.5" class="section-number selfRef">10.5. </a><a href="#name-cbor-tag-registration" class="section-name selfRef">CBOR Tag Registration</a>
        </h3>
<p id="section-10.5-1">This section defines the DOTS CBOR tag as another means for
        applications to declare that a CBOR data structure is a DOTS signal
        channel object. Its use is optional and is intended for use in cases
        in which this information would not otherwise be known. The DOTS CBOR
        tag is not required for the DOTS signal channel protocol version specified
        in this document. If present, the DOTS tag <span class="bcp14">MUST</span> prefix a DOTS signal
        channel object.<a href="#section-10.5-1" class="pilcrow">¶</a></p>
<p id="section-10.5-2">IANA has updated the DOTS signal channel CBOR tag in the
        "CBOR Tags" registry <span>[<a href="#IANA-CBOR-Tags" class="xref">IANA-CBOR-Tags</a>]</span> as follows:<a href="#section-10.5-2" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.5-3">
          <dt id="section-10.5-3.1">Tag:</dt>
          <dd style="margin-left: 1.5em" id="section-10.5-3.2">271<a href="#section-10.5-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.5-3.3">Data Item:</dt>
          <dd style="margin-left: 1.5em" id="section-10.5-3.4">DDoS Open Threat Signaling (DOTS) signal channel object<a href="#section-10.5-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.5-3.5">Semantics:</dt>
          <dd style="margin-left: 1.5em" id="section-10.5-3.6">DDoS Open Threat Signaling (DOTS) signal channel
      object, as defined in [RFC9132]<a href="#section-10.5-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.5-3.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.5-3.8">[RFC9132]<a href="#section-10.5-3.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="reg">
<section id="section-10.6">
        <h3 id="name-dots-signal-channel-protoco">
<a href="#section-10.6" class="section-number selfRef">10.6. </a><a href="#name-dots-signal-channel-protoco" class="section-name selfRef">DOTS Signal Channel Protocol Registry</a>
        </h3>
<p id="section-10.6-1">The following sections update the "Distributed Denial-of-Service
        Open Threat Signaling (DOTS) Signal Channel" subregistries <span>[<a href="#REG-DOTS" class="xref">REG-DOTS</a>]</span>.<a href="#section-10.6-1" class="pilcrow">¶</a></p>
<div id="map">
<section id="section-10.6.1">
          <h4 id="name-dots-signal-channel-cbor-ke">
<a href="#section-10.6.1" class="section-number selfRef">10.6.1. </a><a href="#name-dots-signal-channel-cbor-ke" class="section-name selfRef">DOTS Signal Channel CBOR Key Values Subregistry</a>
          </h4>
<p id="section-10.6.1-1">The structure of this subregistry is provided in <a href="#format" class="xref">Section 10.6.1.1</a>.<a href="#section-10.6.1-1" class="pilcrow">¶</a></p>
<div id="format">
<section id="section-10.6.1.1">
            <h5 id="name-registration-template">
<a href="#section-10.6.1.1" class="section-number selfRef">10.6.1.1. </a><a href="#name-registration-template" class="section-name selfRef">Registration Template</a>
            </h5>
<p id="section-10.6.1.1-1">IANA has updated the allocation
            policy of "DOTS Signal Channel CBOR Key Values" registry as
            follows:<a href="#section-10.6.1.1-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlNewline" id="section-10.6.1.1-2">
              <dt id="section-10.6.1.1-2.1">Parameter name:</dt>
              <dd style="margin-left: 1.5em" id="section-10.6.1.1-2.2">Parameter name, as used
                in the DOTS signal channel.<a href="#section-10.6.1.1-2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.6.1.1-2.3">CBOR Key Value:</dt>
              <dd style="margin-left: 1.5em" id="section-10.6.1.1-2.4">
                <p id="section-10.6.1.1-2.4.1">Key value for the
                parameter. The key value <span class="bcp14">MUST</span> be an integer in the 1-65535
                range.<a href="#section-10.6.1.1-2.4.1" class="pilcrow">¶</a></p>
<p id="section-10.6.1.1-2.4.2">OLD:<a href="#section-10.6.1.1-2.4.2" class="pilcrow">¶</a></p>
<div id="old">
<table class="center" id="table-7">
                  <caption><a href="#table-7" class="selfRef">Table 7</a></caption>
<thead>
                    <tr>
                      <th class="text-left" rowspan="1" colspan="1">Range</th>
                      <th class="text-left" rowspan="1" colspan="1">Registration Procedures</th>
                      <th class="text-left" rowspan="1" colspan="1">Note</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">1-16383</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-required</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">16384-32767</td>
                      <td class="text-left" rowspan="1" colspan="1">Specification Required</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">32768-49151</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">49152-65535</td>
                      <td class="text-left" rowspan="1" colspan="1">Private Use</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                  </tbody>
                </table>
</div>
<p id="section-10.6.1.1-2.4.4">NEW:<a href="#section-10.6.1.1-2.4.4" class="pilcrow">¶</a></p>
<div id="new">
<table class="center" id="table-8">
                  <caption><a href="#table-8" class="selfRef">Table 8</a></caption>
<thead>
                    <tr>
                      <th class="text-left" rowspan="1" colspan="1">Range</th>
                      <th class="text-left" rowspan="1" colspan="1">Registration Procedures</th>
                      <th class="text-left" rowspan="1" colspan="1">Note</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">1-127</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-required</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">128-255</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">256-16383</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-required</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">16384-32767</td>
                      <td class="text-left" rowspan="1" colspan="1">Specification Required</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">32768-49151</td>
                      <td class="text-left" rowspan="1" colspan="1">IETF Review</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                    <tr>
                      <td class="text-left" rowspan="1" colspan="1">49152-65535</td>
                      <td class="text-left" rowspan="1" colspan="1">Private Use</td>
                      <td class="text-left" rowspan="1" colspan="1">comprehension-optional</td>
                    </tr>
                  </tbody>
                </table>
</div>
<p id="section-10.6.1.1-2.4.6">Registration requests for
                the 16384-32767 range are evaluated after a three-week review
                period on the dots-signal-reg-review@ietf.org mailing list, on
                the advice of one or more designated experts. However, to
                allow for the allocation of values prior to publication, the
                designated experts may approve registration once they are
                satisfied that such a specification will be published. New
                registration requests should be sent in the form of an email
                to the review mailing list; the request should use an
                appropriate subject (e.g., "Request to register CBOR Key Value
                for DOTS: example"). IANA will only accept new registrations
                from the designated experts, and it will check that review was
                requested on the mailing list in accordance with these
                procedures.<a href="#section-10.6.1.1-2.4.6" class="pilcrow">¶</a></p>
<p id="section-10.6.1.1-2.4.7">Within the review period,
                the designated experts will either approve or deny the
                registration request, communicating this decision to the
                review list and IANA. Denials should include an explanation
                and, if applicable, suggestions as to how to make the request
                successful. Registration requests that are undetermined for a
                period longer than 21 days can be brought to the IESG's
                attention (using the iesg@ietf.org mailing list) for
                resolution.<a href="#section-10.6.1.1-2.4.7" class="pilcrow">¶</a></p>
<p id="section-10.6.1.1-2.4.8">Criteria that should be
                applied by the designated experts include determining whether
                the proposed registration duplicates existing functionality,
                whether it is likely to be of general applicability or whether
                it is useful only for a single use case, and whether the
                registration description is clear. IANA must only accept
                registry updates to the 16384-32767 range from the designated
                experts and should direct all requests for registration to the
                review mailing list. It is suggested that multiple designated
                experts be appointed. In cases where a registration decision
                could be perceived as creating a conflict of interest for a
                particular expert, that expert should defer to the judgment of
                the other experts.<a href="#section-10.6.1.1-2.4.8" class="pilcrow">¶</a></p>
</dd>
              <dd class="break"></dd>
<dt id="section-10.6.1.1-2.5">CBOR Major Type:</dt>
              <dd style="margin-left: 1.5em" id="section-10.6.1.1-2.6">CBOR Major type and
                optional tag for the parameter.<a href="#section-10.6.1.1-2.6" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.6.1.1-2.7">Change Controller:</dt>
              <dd style="margin-left: 1.5em" id="section-10.6.1.1-2.8">For Standards Track
                RFCs, list the "IESG". For others, give the name of the
                responsible party. Other details (e.g., email address) may
                also be included.<a href="#section-10.6.1.1-2.8" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-10.6.1.1-2.9">Specification Document(s):</dt>
              <dd style="margin-left: 1.5em" id="section-10.6.1.1-2.10">Reference
                to the document or documents that specify the parameter,
                preferably including URIs that can be used to retrieve copies
                of the documents. An indication of the relevant sections may
                also be included but is not required.<a href="#section-10.6.1.1-2.10" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
</section>
</div>
<div id="initial">
<section id="section-10.6.1.2">
            <h5 id="name-update-subregistry-content">
<a href="#section-10.6.1.2" class="section-number selfRef">10.6.1.2. </a><a href="#name-update-subregistry-content" class="section-name selfRef">Update Subregistry Content</a>
            </h5>
<p id="section-10.6.1.2-1">IANA has updated entries in the "0-51" and
            "49152-65535" ranges from the "DOTS Signal Channel CBOR Key
            Values" registry to refer this RFC.<a href="#section-10.6.1.2-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="sc">
<section id="section-10.6.2">
          <h4 id="name-status-codes-subregistry">
<a href="#section-10.6.2" class="section-number selfRef">10.6.2. </a><a href="#name-status-codes-subregistry" class="section-name selfRef">Status Codes Subregistry</a>
          </h4>
<p id="section-10.6.2-1">IANA has updated the following entries from the "DOTS Signal
          Channel Status Codes" registry to refer to this RFC:<a href="#section-10.6.2-1" class="pilcrow">¶</a></p>
<span id="name-initial-dots-signal-channel"></span><div id="table7">
<table class="center" id="table-9">
            <caption>
<a href="#table-9" class="selfRef">Table 9</a>:
<a href="#name-initial-dots-signal-channel" class="selfRef">Initial DOTS Signal Channel Status Codes</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Code</th>
                <th class="text-left" rowspan="1" colspan="1">Label</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
                <th class="text-left" rowspan="1" colspan="1">Reference</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">0</td>
                <td class="text-left" rowspan="1" colspan="1">Reserved</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">attack-mitigation-in-progress</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation setup is in progress (e.g., changing the network path to redirect the inbound traffic to a DOTS mitigator).</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">attack-successfully-mitigated</td>
                <td class="text-left" rowspan="1" colspan="1">Attack is being successfully mitigated (e.g., traffic is redirected to a DDoS mitigator and attack traffic is dropped).</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">3</td>
                <td class="text-left" rowspan="1" colspan="1">attack-stopped</td>
                <td class="text-left" rowspan="1" colspan="1">Attack has stopped and the DOTS client can withdraw the mitigation request.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">4</td>
                <td class="text-left" rowspan="1" colspan="1">attack-exceeded-capability</td>
                <td class="text-left" rowspan="1" colspan="1">Attack has exceeded the mitigation provider capability.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">5</td>
                <td class="text-left" rowspan="1" colspan="1">dots-client-withdrawn-mitigation</td>
                <td class="text-left" rowspan="1" colspan="1">DOTS client has withdrawn the mitigation request and the mitigation is active but terminating.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">6</td>
                <td class="text-left" rowspan="1" colspan="1">attack-mitigation-terminated</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation is now terminated.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">7</td>
                <td class="text-left" rowspan="1" colspan="1">attack-mitigation-withdrawn</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation is withdrawn.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">8</td>
                <td class="text-left" rowspan="1" colspan="1">attack-mitigation-signal-loss</td>
                <td class="text-left" rowspan="1" colspan="1">Attack mitigation will be triggered for the mitigation request only when the DOTS signal channel session is lost.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">9-2147483647</td>
                <td class="text-left" rowspan="1" colspan="1">Unassigned</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1"></td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-10.6.2-3">New codes can be assigned via Standards Action <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-10.6.2-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="cs">
<section id="section-10.6.3">
          <h4 id="name-conflict-status-codes-subre">
<a href="#section-10.6.3" class="section-number selfRef">10.6.3. </a><a href="#name-conflict-status-codes-subre" class="section-name selfRef">Conflict Status Codes Subregistry</a>
          </h4>
<p id="section-10.6.3-1">IANA has updated the following entries from the "DOTS Signal
          Channel Conflict Status Codes" registry to refer to this RFC.<a href="#section-10.6.3-1" class="pilcrow">¶</a></p>
<span id="name-initial-dots-signal-channel-"></span><div id="table8">
<table class="center" id="table-10">
            <caption>
<a href="#table-10" class="selfRef">Table 10</a>:
<a href="#name-initial-dots-signal-channel-" class="selfRef">Initial DOTS Signal Channel Conflict Status Codes</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Code</th>
                <th class="text-left" rowspan="1" colspan="1">Label</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
                <th class="text-left" rowspan="1" colspan="1">Reference</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">0</td>
                <td class="text-left" rowspan="1" colspan="1">Reserved</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">request-inactive-other-active</td>
                <td class="text-left" rowspan="1" colspan="1">DOTS server has detected conflicting mitigation requests from different DOTS clients. This mitigation request is currently inactive until the conflicts are resolved. Another mitigation request is active.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">request-active</td>
                <td class="text-left" rowspan="1" colspan="1">DOTS server has detected conflicting mitigation requests from different DOTS clients. This mitigation request is currently active.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">3</td>
                <td class="text-left" rowspan="1" colspan="1">all-requests-inactive</td>
                <td class="text-left" rowspan="1" colspan="1">DOTS server has detected conflicting mitigation requests from different DOTS clients. All 
conflicting mitigation requests are inactive.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">4-2147483647</td>
                <td class="text-left" rowspan="1" colspan="1">Unassigned</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1"></td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-10.6.3-3">New codes can be assigned via Standards Action <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-10.6.3-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="cc">
<section id="section-10.6.4">
          <h4 id="name-conflict-cause-codes-subreg">
<a href="#section-10.6.4" class="section-number selfRef">10.6.4. </a><a href="#name-conflict-cause-codes-subreg" class="section-name selfRef">Conflict Cause Codes Subregistry</a>
          </h4>
<p id="section-10.6.4-1">IANA has updated the following entries from the "DOTS Signal
          Channel Conflict Cause Codes" registry to refer to this document:<a href="#section-10.6.4-1" class="pilcrow">¶</a></p>
<span id="name-initial-dots-signal-channel-c"></span><div id="table9">
<table class="center" id="table-11">
            <caption>
<a href="#table-11" class="selfRef">Table 11</a>:
<a href="#name-initial-dots-signal-channel-c" class="selfRef">Initial DOTS Signal Channel Conflict Cause Codes</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Code</th>
                <th class="text-left" rowspan="1" colspan="1">Label</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
                <th class="text-left" rowspan="1" colspan="1">Reference</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">0</td>
                <td class="text-left" rowspan="1" colspan="1">Reserved</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">overlapping-targets</td>
                <td class="text-left" rowspan="1" colspan="1">Overlapping targets.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">conflict-with-acceptlist</td>
                <td class="text-left" rowspan="1" colspan="1">Conflicts with an existing accept-list. This code is returned when the DDoS mitigation detects source addresses/prefixes in the accept-listed ACLs are attacking the target.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">3</td>
                <td class="text-left" rowspan="1" colspan="1">cuid-collision</td>
                <td class="text-left" rowspan="1" colspan="1">CUID Collision. This code is returned when a DOTS client uses a 'cuid' that is already used by another DOTS client.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">4-2147483647</td>
                <td class="text-left" rowspan="1" colspan="1">Unassigned</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1"></td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-10.6.4-3">New codes can be assigned via Standards Action <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-10.6.4-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="as">
<section id="section-10.6.5">
          <h4 id="name-attack-status-codes-subregi">
<a href="#section-10.6.5" class="section-number selfRef">10.6.5. </a><a href="#name-attack-status-codes-subregi" class="section-name selfRef">Attack Status Codes Subregistry</a>
          </h4>
<p id="section-10.6.5-1">IANA has updated the following entries from the "DOTS Signal
          Channel Attack Status Codes" registry to refer to this RFC:<a href="#section-10.6.5-1" class="pilcrow">¶</a></p>
<span id="name-initial-dots-signal-channel-a"></span><div id="table10">
<table class="center" id="table-12">
            <caption>
<a href="#table-12" class="selfRef">Table 12</a>:
<a href="#name-initial-dots-signal-channel-a" class="selfRef">Initial DOTS Signal Channel Attack Status Codes</a>
            </caption>
<thead>
              <tr>
                <th class="text-left" rowspan="1" colspan="1">Code</th>
                <th class="text-left" rowspan="1" colspan="1">Label</th>
                <th class="text-left" rowspan="1" colspan="1">Description</th>
                <th class="text-left" rowspan="1" colspan="1">Reference</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">0</td>
                <td class="text-left" rowspan="1" colspan="1">Reserved</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">1</td>
                <td class="text-left" rowspan="1" colspan="1">under-attack</td>
                <td class="text-left" rowspan="1" colspan="1">The DOTS client determines that it is still under attack.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">2</td>
                <td class="text-left" rowspan="1" colspan="1">attack-successfully-mitigated</td>
                <td class="text-left" rowspan="1" colspan="1">The DOTS client determines that the attack is successfully mitigated.</td>
                <td class="text-left" rowspan="1" colspan="1">[RFC9132]</td>
              </tr>
              <tr>
                <td class="text-left" rowspan="1" colspan="1">3-2147483647</td>
                <td class="text-left" rowspan="1" colspan="1">Unassigned</td>
                <td class="text-left" rowspan="1" colspan="1"></td>
                <td class="text-left" rowspan="1" colspan="1"></td>
              </tr>
            </tbody>
          </table>
</div>
<p id="section-10.6.5-3">New codes can be assigned via Standards Action <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-10.6.5-3" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="yang">
<section id="section-10.7">
        <h3 id="name-dots-signal-channel-yang-mod">
<a href="#section-10.7" class="section-number selfRef">10.7. </a><a href="#name-dots-signal-channel-yang-mod" class="section-name selfRef">DOTS Signal Channel YANG Modules</a>
        </h3>
<p id="section-10.7-1">IANA has registered the following URIs in the "ns" subregistry
        within the "IETF XML Registry" <span>[<a href="#RFC3688" class="xref">RFC3688</a>]</span>:<a href="#section-10.7-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.7-2">
          <dt id="section-10.7-2.1">URI:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-2.2">urn:ietf:params:xml:ns:yang:ietf-dots-signal-channel<a href="#section-10.7-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-2.3">Registrant Contact:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-2.4">The IESG.<a href="#section-10.7-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-2.5">XML:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-2.6">N/A; the requested URI is an XML namespace.<a href="#section-10.7-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.7-3">
          <dt id="section-10.7-3.1">URI:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-3.2">urn:ietf:params:xml:ns:yang:iana-dots-signal-channel<a href="#section-10.7-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-3.3">Registrant Contact:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-3.4">IANA.<a href="#section-10.7-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-3.5">XML:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-3.6">N/A; the requested URI is an XML namespace.<a href="#section-10.7-3.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-10.7-4">IANA has updated the following YANG
        module in the "YANG Module Names" subregistry <span>[<a href="#RFC6020" class="xref">RFC6020</a>]</span> within the "YANG Parameters" registry.<a href="#section-10.7-4" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.7-5">
          <dt id="section-10.7-5.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-5.2">iana-dots-signal-channel<a href="#section-10.7-5.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-5.3">Maintained by IANA:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-5.4">Y<a href="#section-10.7-5.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-5.5">Namespace:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-5.6">urn:ietf:params:xml:ns:yang:iana-dots-signal-channel<a href="#section-10.7-5.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-5.7">Prefix:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-5.8">iana-dots-signal<a href="#section-10.7-5.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-5.9">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-5.10">[RFC9132]<a href="#section-10.7-5.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-10.7-6">IANA has registered the additional following YANG module in the "YANG Module
 Names" subregistry <span>[<a href="#RFC6020" class="xref">RFC6020</a>]</span> within the "YANG Parameters" registry.  This obsoletes the registration in <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span>.<a href="#section-10.7-6" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-10.7-7">
          <dt id="section-10.7-7.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-7.2">ietf-dots-signal-channel<a href="#section-10.7-7.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-7.3">Maintained by IANA:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-7.4">N<a href="#section-10.7-7.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-7.5">Namespace:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-7.6">urn:ietf:params:xml:ns:yang:ietf-dots-signal-channel<a href="#section-10.7-7.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-7.7">Prefix:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-7.8">dots-signal<a href="#section-10.7-7.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-7.9">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.7-7.10">[RFC9132]<a href="#section-10.7-7.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-10.7-8">This document obsoletes the initial version of the IANA-maintained
        iana-dots-signal-channel YANG module (<span><a href="https://www.rfc-editor.org/rfc/rfc8782#section-5.2" class="relref">Section 5.2</a> of [<a href="#RFC8782" class="xref">RFC8782</a>]</span>). IANA is requested to maintain
        this note:<a href="#section-10.7-8" class="pilcrow">¶</a></p>
<p style="margin-left: 2.5em" id="section-10.7-9">Status, conflict status, conflict cause, and attack
   status
            values must not be directly added to the iana-dots-signal-channel
            YANG module. They must instead be respectively added to the "DOTS
            Status Codes", "DOTS Conflict Status Codes", "DOTS Conflict Cause
            Codes", and "DOTS Attack Status Codes" registries.<a href="#section-10.7-9" class="pilcrow">¶</a></p>
<p id="section-10.7-10">When a 'status', 'conflict-status', 'conflict-cause', or
        'attack-status' value is respectively added to the "DOTS Status
        Codes", "DOTS Conflict Status Codes", "DOTS Conflict Cause Codes", or
        "DOTS Attack Status Codes" registry, a new "enum" statement must be
        added to the iana-dots-signal-channel YANG module. The following
        "enum" statement, and substatements thereof, should be defined:<a href="#section-10.7-10" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-10.7-11">
          <dt id="section-10.7-11.1">"enum":</dt>
          <dd style="margin-left: 8.0em" id="section-10.7-11.2">Replicates the label from the
            registry.<a href="#section-10.7-11.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-11.3">"value":</dt>
          <dd style="margin-left: 8.0em" id="section-10.7-11.4">Contains the IANA-assigned value
            corresponding to the 'status', 'conflict-status',
            'conflict-cause', or 'attack-status'.<a href="#section-10.7-11.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-11.5">"description":</dt>
          <dd style="margin-left: 8.0em" id="section-10.7-11.6">Replicates the description
            from the registry.<a href="#section-10.7-11.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.7-11.7">"reference":</dt>
          <dd style="margin-left: 8.0em" id="section-10.7-11.8">Replicates the reference from
            the registry and adds the title of the document.<a href="#section-10.7-11.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-10.7-12">When the iana-dots-signal-channel YANG module is updated, a new
        "revision" statement must be added in front of the existing revision
        statements.<a href="#section-10.7-12" class="pilcrow">¶</a></p>
<p id="section-10.7-13">IANA has updated this note in "DOTS Status Codes", "DOTS
        Conflict Status Codes", "DOTS Conflict Cause Codes", and "DOTS Attack
        Status Codes" registries:<a href="#section-10.7-13" class="pilcrow">¶</a></p>
<p style="margin-left: 2.5em" id="section-10.7-14">When this registry is modified, the YANG module
            iana-dots-signal-channel must be updated as defined in
            [RFC9132].<a href="#section-10.7-14" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="security">
<section id="section-11">
      <h2 id="name-security-considerations">
<a href="#section-11" class="section-number selfRef">11. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-11-1">High-level DOTS security considerations are documented in <span>[<a href="#RFC8612" class="xref">RFC8612</a>]</span> and <span>[<a href="#RFC8811" class="xref">RFC8811</a>]</span>.<a href="#section-11-1" class="pilcrow">¶</a></p>
<p id="section-11-2">Authenticated encryption <span class="bcp14">MUST</span> be used for data confidentiality and
      message integrity. The interaction between the DOTS agents requires
      Datagram Transport Layer Security (DTLS) or Transport Layer Security
      (TLS) with a cipher suite offering confidentiality protection, and the
      guidance given in <span>[<a href="#RFC7525" class="xref">RFC7525</a>]</span> <span class="bcp14">MUST</span> be followed to
      avoid attacks on (D)TLS. The (D)TLS protocol profile used for the DOTS
      signal channel is specified in <a href="#profile" class="xref">Section 7</a>.<a href="#section-11-2" class="pilcrow">¶</a></p>
<p id="section-11-3">If TCP is used between DOTS agents, an attacker may be able to inject
      RST packets, bogus application segments, etc., regardless of whether TLS
      authentication is used. Because the application data is TLS protected,
      this will not result in the application receiving bogus data, but it
      will constitute a DoS on the connection. This attack can be countered by
      using TCP Authentication Option (TCP-AO) <span>[<a href="#RFC5925" class="xref">RFC5925</a>]</span>.
      Although not widely adopted, if TCP-AO is used, then any bogus packets
      injected by an attacker will be rejected by the TCP-AO integrity check
      and therefore will never reach the TLS layer.<a href="#section-11-3" class="pilcrow">¶</a></p>
<p id="section-11-4">If the 'cuid' is guessable, a misbehaving DOTS client from within the
      client's domain can use the 'cuid' of another DOTS client of the domain
      to delete or alter active mitigations. For this attack to succeed, the
      misbehaving client's messages need to pass the security validation
      checks by the DOTS server and, if the communication involves a
      client-domain DOTS gateway, the security checks of that gateway.<a href="#section-11-4" class="pilcrow">¶</a></p>
<p id="section-11-5">A similar attack can be achieved by a compromised DOTS client that
      can sniff the TLS 1.2 handshake: use the client certificate to identify
      the 'cuid' used by another DOTS client. This attack is not possible if
      algorithms such as version 4 Universally Unique IDentifiers (UUIDs) in
      <span><a href="https://www.rfc-editor.org/rfc/rfc4122#section-4.4" class="relref">Section 4.4</a> of [<a href="#RFC4122" class="xref">RFC4122</a>]</span> are used to generate the
      'cuid' because such UUIDs are not a deterministic function of the client
      certificate. Likewise, this attack is not possible with TLS 1.3 because
      most of the TLS handshake is encrypted and the client certificate is not
      visible to eavesdroppers.<a href="#section-11-5" class="pilcrow">¶</a></p>
<p id="section-11-6">A compromised DOTS client can collude with a DDoS attacker to send a
      mitigation request for a target resource, get the mitigation efficacy
      from the DOTS server, and convey the mitigation efficacy to the DDoS
      attacker to possibly change the DDoS attack strategy. Obviously,
      signaling an attack by the compromised DOTS client to the DOTS server
      will trigger attack mitigation. This attack can be prevented by
      monitoring and auditing DOTS clients to detect misbehavior and to deter
      misuse and by only authorizing the DOTS client to request mitigation
      for specific target resources (e.g., an application server is authorized
      to request mitigation for its IP addresses, but a DDoS mitigator can
      request mitigation for any target resource in the network). Furthermore,
      DOTS clients are typically co-located on network security services
      (e.g., firewall), and a compromised security service potentially can do
      a lot more damage to the network.<a href="#section-11-6" class="pilcrow">¶</a></p>
<p id="section-11-7">Rate-limiting DOTS requests, including those with new 'cuid' values,
      from the same DOTS client defend against DoS attacks that would result
      in varying the 'cuid' to exhaust DOTS server resources. Rate-limit
      policies <span class="bcp14">SHOULD</span> be enforced on DOTS gateways (if deployed) and DOTS
      servers.<a href="#section-11-7" class="pilcrow">¶</a></p>
<p id="section-11-8">In order to prevent leaking internal information outside a client's
      domain, DOTS gateways located in the client domain <span class="bcp14">SHOULD NOT</span> reveal the
      identification information that pertains to internal DOTS clients (e.g.,
      source IP address, client's hostname) unless explicitly configured to do
      so.<a href="#section-11-8" class="pilcrow">¶</a></p>
<p id="section-11-9">DOTS servers <span class="bcp14">MUST</span> verify that requesting DOTS clients are entitled to
      trigger actions on a given IP prefix. A DOTS server <span class="bcp14">MUST NOT</span> authorize
      actions due to a DOTS client request unless those actions are limited to
      that DOTS client's domain IP resources. The exact mechanism for the DOTS
      servers to validate that the target prefixes are within the scope of the
      DOTS client domain is deployment specific.<a href="#section-11-9" class="pilcrow">¶</a></p>
<p id="section-11-10">The presence of DOTS gateways may lead to infinite forwarding loops,
      which is undesirable. To prevent and detect such loops, this document
      uses the Hop-Limit Option.<a href="#section-11-10" class="pilcrow">¶</a></p>
<p id="section-11-11">When FQDNs are used as targets, the DOTS server <span class="bcp14">MUST</span> rely upon DNS
      privacy-enabling protocols (e.g., DNS over TLS <span>[<a href="#RFC7858" class="xref">RFC7858</a>]</span> or DNS over HTTPS (DoH) <span>[<a href="#RFC8484" class="xref">RFC8484</a>]</span>) to prevent eavesdroppers from possibly
      identifying the target resources protected by the DDoS mitigation
      service to ensure the target FQDN resolution is authentic (e.g., DNSSEC
      <span>[<a href="#RFC4034" class="xref">RFC4034</a>]</span>).<a href="#section-11-11" class="pilcrow">¶</a></p>
<p id="section-11-12">CoAP-specific security considerations are discussed in
      <span><a href="https://www.rfc-editor.org/rfc/rfc7252#section-11" class="relref">Section 11</a> of [<a href="#RFC7252" class="xref">RFC7252</a>]</span>, while CBOR-related security
      considerations are discussed in <span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-10" class="relref">Section 10</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>.<a href="#section-11-12" class="pilcrow">¶</a></p>
<p id="section-11-13">This document defines YANG data structures that are meant to be used
      as an abstract representation of DOTS signal channel messages. As such,
      the "ietf-dots-signal-channel" module does not introduce any new
      vulnerabilities beyond those specified above.<a href="#section-11-13" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-12">
      <h2 id="name-references">
<a href="#section-12" class="section-number selfRef">12. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-12.1">
        <h3 id="name-normative-references">
<a href="#section-12.1" class="section-number selfRef">12.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="RFC0791">[RFC0791]</dt>
        <dd>
<span class="refAuthor">Postel, J.</span>, <span class="refTitle">"Internet Protocol"</span>, <span class="seriesInfo">STD 5</span>, <span class="seriesInfo">RFC 791</span>, <span class="seriesInfo">DOI 10.17487/RFC0791</span>, <time datetime="1981-09" class="refDate">September 1981</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc791">https://www.rfc-editor.org/info/rfc791</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC1122">[RFC1122]</dt>
        <dd>
<span class="refAuthor">Braden, R., Ed.</span>, <span class="refTitle">"Requirements for Internet Hosts - Communication Layers"</span>, <span class="seriesInfo">STD 3</span>, <span class="seriesInfo">RFC 1122</span>, <span class="seriesInfo">DOI 10.17487/RFC1122</span>, <time datetime="1989-10" class="refDate">October 1989</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc1122">https://www.rfc-editor.org/info/rfc1122</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2119">[RFC2119]</dt>
        <dd>
<span class="refAuthor">Bradner, S.</span>, <span class="refTitle">"Key words for use in RFCs to Indicate Requirement Levels"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 2119</span>, <span class="seriesInfo">DOI 10.17487/RFC2119</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2119">https://www.rfc-editor.org/info/rfc2119</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3688">[RFC3688]</dt>
        <dd>
<span class="refAuthor">Mealling, M.</span>, <span class="refTitle">"The IETF XML Registry"</span>, <span class="seriesInfo">BCP 81</span>, <span class="seriesInfo">RFC 3688</span>, <span class="seriesInfo">DOI 10.17487/RFC3688</span>, <time datetime="2004-01" class="refDate">January 2004</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3688">https://www.rfc-editor.org/info/rfc3688</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3986">[RFC3986]</dt>
        <dd>
<span class="refAuthor">Berners-Lee, T.</span>, <span class="refAuthor">Fielding, R.</span>, and <span class="refAuthor">L. Masinter</span>, <span class="refTitle">"Uniform Resource Identifier (URI): Generic Syntax"</span>, <span class="seriesInfo">STD 66</span>, <span class="seriesInfo">RFC 3986</span>, <span class="seriesInfo">DOI 10.17487/RFC3986</span>, <time datetime="2005-01" class="refDate">January 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3986">https://www.rfc-editor.org/info/rfc3986</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4279">[RFC4279]</dt>
        <dd>
<span class="refAuthor">Eronen, P., Ed.</span> and <span class="refAuthor">H. Tschofenig, Ed.</span>, <span class="refTitle">"Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"</span>, <span class="seriesInfo">RFC 4279</span>, <span class="seriesInfo">DOI 10.17487/RFC4279</span>, <time datetime="2005-12" class="refDate">December 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4279">https://www.rfc-editor.org/info/rfc4279</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4632">[RFC4632]</dt>
        <dd>
<span class="refAuthor">Fuller, V.</span> and <span class="refAuthor">T. Li</span>, <span class="refTitle">"Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan"</span>, <span class="seriesInfo">BCP 122</span>, <span class="seriesInfo">RFC 4632</span>, <span class="seriesInfo">DOI 10.17487/RFC4632</span>, <time datetime="2006-08" class="refDate">August 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4632">https://www.rfc-editor.org/info/rfc4632</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4648">[RFC4648]</dt>
        <dd>
<span class="refAuthor">Josefsson, S.</span>, <span class="refTitle">"The Base16, Base32, and Base64 Data Encodings"</span>, <span class="seriesInfo">RFC 4648</span>, <span class="seriesInfo">DOI 10.17487/RFC4648</span>, <time datetime="2006-10" class="refDate">October 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4648">https://www.rfc-editor.org/info/rfc4648</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5246">[RFC5246]</dt>
        <dd>
<span class="refAuthor">Dierks, T.</span> and <span class="refAuthor">E. Rescorla</span>, <span class="refTitle">"The Transport Layer Security (TLS) Protocol Version 1.2"</span>, <span class="seriesInfo">RFC 5246</span>, <span class="seriesInfo">DOI 10.17487/RFC5246</span>, <time datetime="2008-08" class="refDate">August 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5246">https://www.rfc-editor.org/info/rfc5246</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5280">[RFC5280]</dt>
        <dd>
<span class="refAuthor">Cooper, D.</span>, <span class="refAuthor">Santesson, S.</span>, <span class="refAuthor">Farrell, S.</span>, <span class="refAuthor">Boeyen, S.</span>, <span class="refAuthor">Housley, R.</span>, and <span class="refAuthor">W. Polk</span>, <span class="refTitle">"Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"</span>, <span class="seriesInfo">RFC 5280</span>, <span class="seriesInfo">DOI 10.17487/RFC5280</span>, <time datetime="2008-05" class="refDate">May 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5280">https://www.rfc-editor.org/info/rfc5280</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6020">[RFC6020]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refTitle">"YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)"</span>, <span class="seriesInfo">RFC 6020</span>, <span class="seriesInfo">DOI 10.17487/RFC6020</span>, <time datetime="2010-10" class="refDate">October 2010</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6020">https://www.rfc-editor.org/info/rfc6020</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6066">[RFC6066]</dt>
        <dd>
<span class="refAuthor">Eastlake 3rd, D.</span>, <span class="refTitle">"Transport Layer Security (TLS) Extensions: Extension Definitions"</span>, <span class="seriesInfo">RFC 6066</span>, <span class="seriesInfo">DOI 10.17487/RFC6066</span>, <time datetime="2011-01" class="refDate">January 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6066">https://www.rfc-editor.org/info/rfc6066</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6125">[RFC6125]</dt>
        <dd>
<span class="refAuthor">Saint-Andre, P.</span> and <span class="refAuthor">J. Hodges</span>, <span class="refTitle">"Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)"</span>, <span class="seriesInfo">RFC 6125</span>, <span class="seriesInfo">DOI 10.17487/RFC6125</span>, <time datetime="2011-03" class="refDate">March 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6125">https://www.rfc-editor.org/info/rfc6125</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6347">[RFC6347]</dt>
        <dd>
<span class="refAuthor">Rescorla, E.</span> and <span class="refAuthor">N. Modadugu</span>, <span class="refTitle">"Datagram Transport Layer Security Version 1.2"</span>, <span class="seriesInfo">RFC 6347</span>, <span class="seriesInfo">DOI 10.17487/RFC6347</span>, <time datetime="2012-01" class="refDate">January 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6347">https://www.rfc-editor.org/info/rfc6347</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6991">[RFC6991]</dt>
        <dd>
<span class="refAuthor">Schoenwaelder, J., Ed.</span>, <span class="refTitle">"Common YANG Data Types"</span>, <span class="seriesInfo">RFC 6991</span>, <span class="seriesInfo">DOI 10.17487/RFC6991</span>, <time datetime="2013-07" class="refDate">July 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6991">https://www.rfc-editor.org/info/rfc6991</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7250">[RFC7250]</dt>
        <dd>
<span class="refAuthor">Wouters, P., Ed.</span>, <span class="refAuthor">Tschofenig, H., Ed.</span>, <span class="refAuthor">Gilmore, J.</span>, <span class="refAuthor">Weiler, S.</span>, and <span class="refAuthor">T. Kivinen</span>, <span class="refTitle">"Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"</span>, <span class="seriesInfo">RFC 7250</span>, <span class="seriesInfo">DOI 10.17487/RFC7250</span>, <time datetime="2014-06" class="refDate">June 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7250">https://www.rfc-editor.org/info/rfc7250</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7252">[RFC7252]</dt>
        <dd>
<span class="refAuthor">Shelby, Z.</span>, <span class="refAuthor">Hartke, K.</span>, and <span class="refAuthor">C. Bormann</span>, <span class="refTitle">"The Constrained Application Protocol (CoAP)"</span>, <span class="seriesInfo">RFC 7252</span>, <span class="seriesInfo">DOI 10.17487/RFC7252</span>, <time datetime="2014-06" class="refDate">June 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7252">https://www.rfc-editor.org/info/rfc7252</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7525">[RFC7525]</dt>
        <dd>
<span class="refAuthor">Sheffer, Y.</span>, <span class="refAuthor">Holz, R.</span>, and <span class="refAuthor">P. Saint-Andre</span>, <span class="refTitle">"Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"</span>, <span class="seriesInfo">BCP 195</span>, <span class="seriesInfo">RFC 7525</span>, <span class="seriesInfo">DOI 10.17487/RFC7525</span>, <time datetime="2015-05" class="refDate">May 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7525">https://www.rfc-editor.org/info/rfc7525</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7641">[RFC7641]</dt>
        <dd>
<span class="refAuthor">Hartke, K.</span>, <span class="refTitle">"Observing Resources in the Constrained Application Protocol (CoAP)"</span>, <span class="seriesInfo">RFC 7641</span>, <span class="seriesInfo">DOI 10.17487/RFC7641</span>, <time datetime="2015-09" class="refDate">September 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7641">https://www.rfc-editor.org/info/rfc7641</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7918">[RFC7918]</dt>
        <dd>
<span class="refAuthor">Langley, A.</span>, <span class="refAuthor">Modadugu, N.</span>, and <span class="refAuthor">B. Moeller</span>, <span class="refTitle">"Transport Layer Security (TLS) False Start"</span>, <span class="seriesInfo">RFC 7918</span>, <span class="seriesInfo">DOI 10.17487/RFC7918</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7918">https://www.rfc-editor.org/info/rfc7918</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7924">[RFC7924]</dt>
        <dd>
<span class="refAuthor">Santesson, S.</span> and <span class="refAuthor">H. Tschofenig</span>, <span class="refTitle">"Transport Layer Security (TLS) Cached Information Extension"</span>, <span class="seriesInfo">RFC 7924</span>, <span class="seriesInfo">DOI 10.17487/RFC7924</span>, <time datetime="2016-07" class="refDate">July 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7924">https://www.rfc-editor.org/info/rfc7924</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7950">[RFC7950]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refTitle">"The YANG 1.1 Data Modeling Language"</span>, <span class="seriesInfo">RFC 7950</span>, <span class="seriesInfo">DOI 10.17487/RFC7950</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7950">https://www.rfc-editor.org/info/rfc7950</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7959">[RFC7959]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span> and <span class="refAuthor">Z. Shelby, Ed.</span>, <span class="refTitle">"Block-Wise Transfers in the Constrained Application Protocol (CoAP)"</span>, <span class="seriesInfo">RFC 7959</span>, <span class="seriesInfo">DOI 10.17487/RFC7959</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7959">https://www.rfc-editor.org/info/rfc7959</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8085">[RFC8085]</dt>
        <dd>
<span class="refAuthor">Eggert, L.</span>, <span class="refAuthor">Fairhurst, G.</span>, and <span class="refAuthor">G. Shepherd</span>, <span class="refTitle">"UDP Usage Guidelines"</span>, <span class="seriesInfo">BCP 145</span>, <span class="seriesInfo">RFC 8085</span>, <span class="seriesInfo">DOI 10.17487/RFC8085</span>, <time datetime="2017-03" class="refDate">March 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8085">https://www.rfc-editor.org/info/rfc8085</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8126">[RFC8126]</dt>
        <dd>
<span class="refAuthor">Cotton, M.</span>, <span class="refAuthor">Leiba, B.</span>, and <span class="refAuthor">T. Narten</span>, <span class="refTitle">"Guidelines for Writing an IANA Considerations Section in RFCs"</span>, <span class="seriesInfo">BCP 26</span>, <span class="seriesInfo">RFC 8126</span>, <span class="seriesInfo">DOI 10.17487/RFC8126</span>, <time datetime="2017-06" class="refDate">June 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8126">https://www.rfc-editor.org/info/rfc8126</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
        <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8200">[RFC8200]</dt>
        <dd>
<span class="refAuthor">Deering, S.</span> and <span class="refAuthor">R. Hinden</span>, <span class="refTitle">"Internet Protocol, Version 6 (IPv6) Specification"</span>, <span class="seriesInfo">STD 86</span>, <span class="seriesInfo">RFC 8200</span>, <span class="seriesInfo">DOI 10.17487/RFC8200</span>, <time datetime="2017-07" class="refDate">July 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8200">https://www.rfc-editor.org/info/rfc8200</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8305">[RFC8305]</dt>
        <dd>
<span class="refAuthor">Schinazi, D.</span> and <span class="refAuthor">T. Pauly</span>, <span class="refTitle">"Happy Eyeballs Version 2: Better Connectivity Using Concurrency"</span>, <span class="seriesInfo">RFC 8305</span>, <span class="seriesInfo">DOI 10.17487/RFC8305</span>, <time datetime="2017-12" class="refDate">December 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8305">https://www.rfc-editor.org/info/rfc8305</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8323">[RFC8323]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span>, <span class="refAuthor">Lemay, S.</span>, <span class="refAuthor">Tschofenig, H.</span>, <span class="refAuthor">Hartke, K.</span>, <span class="refAuthor">Silverajan, B.</span>, and <span class="refAuthor">B. Raymor, Ed.</span>, <span class="refTitle">"CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets"</span>, <span class="seriesInfo">RFC 8323</span>, <span class="seriesInfo">DOI 10.17487/RFC8323</span>, <time datetime="2018-02" class="refDate">February 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8323">https://www.rfc-editor.org/info/rfc8323</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8446">[RFC8446]</dt>
        <dd>
<span class="refAuthor">Rescorla, E.</span>, <span class="refTitle">"The Transport Layer Security (TLS) Protocol Version 1.3"</span>, <span class="seriesInfo">RFC 8446</span>, <span class="seriesInfo">DOI 10.17487/RFC8446</span>, <time datetime="2018-08" class="refDate">August 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8446">https://www.rfc-editor.org/info/rfc8446</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8615">[RFC8615]</dt>
        <dd>
<span class="refAuthor">Nottingham, M.</span>, <span class="refTitle">"Well-Known Uniform Resource Identifiers (URIs)"</span>, <span class="seriesInfo">RFC 8615</span>, <span class="seriesInfo">DOI 10.17487/RFC8615</span>, <time datetime="2019-05" class="refDate">May 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8615">https://www.rfc-editor.org/info/rfc8615</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8768">[RFC8768]</dt>
        <dd>
<span class="refAuthor">Boucadair, M.</span>, <span class="refAuthor">Reddy.K, T.</span>, and <span class="refAuthor">J. Shallow</span>, <span class="refTitle">"Constrained Application Protocol (CoAP) Hop-Limit Option"</span>, <span class="seriesInfo">RFC 8768</span>, <span class="seriesInfo">DOI 10.17487/RFC8768</span>, <time datetime="2020-03" class="refDate">March 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8768">https://www.rfc-editor.org/info/rfc8768</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8783">[RFC8783]</dt>
        <dd>
<span class="refAuthor">Boucadair, M., Ed.</span> and <span class="refAuthor">T. Reddy.K, Ed.</span>, <span class="refTitle">"Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel Specification"</span>, <span class="seriesInfo">RFC 8783</span>, <span class="seriesInfo">DOI 10.17487/RFC8783</span>, <time datetime="2020-05" class="refDate">May 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8783">https://www.rfc-editor.org/info/rfc8783</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8791">[RFC8791]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span>, <span class="refAuthor">Björklund, M.</span>, and <span class="refAuthor">K. Watsen</span>, <span class="refTitle">"YANG Data Structure Extensions"</span>, <span class="seriesInfo">RFC 8791</span>, <span class="seriesInfo">DOI 10.17487/RFC8791</span>, <time datetime="2020-06" class="refDate">June 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8791">https://www.rfc-editor.org/info/rfc8791</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8949">[RFC8949]</dt>
      <dd>
<span class="refAuthor">Bormann, C.</span> and <span class="refAuthor">P. Hoffman</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR)"</span>, <span class="seriesInfo">STD 94</span>, <span class="seriesInfo">RFC 8949</span>, <span class="seriesInfo">DOI 10.17487/RFC8949</span>, <time datetime="2020-12" class="refDate">December 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8949">https://www.rfc-editor.org/info/rfc8949</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-12.2">
        <h3 id="name-informative-references">
<a href="#section-12.2" class="section-number selfRef">12.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="I-D.ietf-core-comi">[CORE-COMI]</dt>
        <dd>
<span class="refAuthor">Veillette, M., Ed.</span>, <span class="refAuthor">Stok, P., Ed.</span>, <span class="refAuthor">Pelov, A.</span>, <span class="refAuthor">Bierman, A.</span>, and <span class="refAuthor">I. Petrov</span>, <span class="refTitle">"CoAP Management Interface (CORECONF)"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-core-comi-11</span>, <time datetime="2021-01-17" class="refDate">17 January 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-core-comi-11">https://datatracker.ietf.org/doc/html/draft-ietf-core-comi-11</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.ietf-core-yang-cbor">[CORE-YANG-CBOR]</dt>
        <dd>
<span class="refAuthor">Veillette, M., Ed.</span>, <span class="refAuthor">Petrov, I., Ed.</span>, and <span class="refAuthor">A. Pelov</span>, <span class="refTitle">"CBOR Encoding of Data Modeled with YANG"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-core-yang-cbor-16</span>, <time datetime="2021-01-25" class="refDate">25 January 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-core-yang-cbor-16">https://datatracker.ietf.org/doc/html/draft-ietf-core-yang-cbor-16</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.boucadair-dots-earlydata">[DOTS-EARLYDATA]</dt>
        <dd>
<span class="refAuthor">Boucadair, M.</span> and <span class="refAuthor">T. Reddy.K</span>, <span class="refTitle">"Using Early Data in DOTS"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-boucadair-dots-earlydata-00</span>, <time datetime="2019-01-29" class="refDate">29 January 2019</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-boucadair-dots-earlydata-00">https://datatracker.ietf.org/doc/html/draft-boucadair-dots-earlydata-00</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.ietf-dots-multihoming">[DOTS-MULTIHOMING]</dt>
        <dd>
<span class="refAuthor">Boucadair, M.</span>, <span class="refAuthor">Reddy.K, T.</span>, and <span class="refAuthor">W. Pan</span>, <span class="refTitle">"Multi-homing Deployment Considerations for Distributed-Denial-of-Service Open Threat Signaling (DOTS)"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-dots-multihoming-07</span>, <time datetime="2021-07-06" class="refDate">6 July 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-dots-multihoming-07">https://datatracker.ietf.org/doc/html/draft-ietf-dots-multihoming-07</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.ietf-dots-telemetry">[DOTS-TELEMETRY]</dt>
        <dd>
<span class="refAuthor">Boucadair, M., Ed.</span>, <span class="refAuthor">Reddy.K, T., Ed.</span>, <span class="refAuthor">Doron, E.</span>, <span class="refAuthor">Chen, M.</span>, and <span class="refAuthor">J. Shallow</span>, <span class="refTitle">"Distributed Denial-of-Service Open Threat Signaling (DOTS) Telemetry"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-dots-telemetry-16</span>, <time datetime="2020-12-08" class="refDate">8 December 2020</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-dots-telemetry-16">https://datatracker.ietf.org/doc/html/draft-ietf-dots-telemetry-16</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA-CBOR-Tags">[IANA-CBOR-Tags]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR) Tags"</span>, <span>&lt;<a href="https://www.iana.org/assignments/cbor-tags">https://www.iana.org/assignments/cbor-tags</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA-CoAP-Content-Formats">[IANA-CoAP-Content-Formats]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"CoAP Content-Formats"</span>, <span>&lt;<a href="https://www.iana.org/assignments/core-parameters">https://www.iana.org/assignments/core-parameters</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA-MediaTypes">[IANA-MediaTypes]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Media Types"</span>, <span>&lt;<a href="https://www.iana.org/assignments/media-types">https://www.iana.org/assignments/media-types</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA-Proto">[IANA-Proto]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Protocol Numbers"</span>, <span>&lt;<a href="https://www.iana.org/assignments/protocol-numbers">https://www.iana.org/assignments/protocol-numbers</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="REG-DOTS">[REG-DOTS]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel"</span>, <span>&lt;<a href="https://www.iana.org/assignments/dots">https://www.iana.org/assignments/dots</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3022">[RFC3022]</dt>
        <dd>
<span class="refAuthor">Srisuresh, P.</span> and <span class="refAuthor">K. Egevang</span>, <span class="refTitle">"Traditional IP Network Address Translator (Traditional NAT)"</span>, <span class="seriesInfo">RFC 3022</span>, <span class="seriesInfo">DOI 10.17487/RFC3022</span>, <time datetime="2001-01" class="refDate">January 2001</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3022">https://www.rfc-editor.org/info/rfc3022</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4034">[RFC4034]</dt>
        <dd>
<span class="refAuthor">Arends, R.</span>, <span class="refAuthor">Austein, R.</span>, <span class="refAuthor">Larson, M.</span>, <span class="refAuthor">Massey, D.</span>, and <span class="refAuthor">S. Rose</span>, <span class="refTitle">"Resource Records for the DNS Security Extensions"</span>, <span class="seriesInfo">RFC 4034</span>, <span class="seriesInfo">DOI 10.17487/RFC4034</span>, <time datetime="2005-03" class="refDate">March 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4034">https://www.rfc-editor.org/info/rfc4034</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4122">[RFC4122]</dt>
        <dd>
<span class="refAuthor">Leach, P.</span>, <span class="refAuthor">Mealling, M.</span>, and <span class="refAuthor">R. Salz</span>, <span class="refTitle">"A Universally Unique IDentifier (UUID) URN Namespace"</span>, <span class="seriesInfo">RFC 4122</span>, <span class="seriesInfo">DOI 10.17487/RFC4122</span>, <time datetime="2005-07" class="refDate">July 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4122">https://www.rfc-editor.org/info/rfc4122</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4340">[RFC4340]</dt>
        <dd>
<span class="refAuthor">Kohler, E.</span>, <span class="refAuthor">Handley, M.</span>, and <span class="refAuthor">S. Floyd</span>, <span class="refTitle">"Datagram Congestion Control Protocol (DCCP)"</span>, <span class="seriesInfo">RFC 4340</span>, <span class="seriesInfo">DOI 10.17487/RFC4340</span>, <time datetime="2006-03" class="refDate">March 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4340">https://www.rfc-editor.org/info/rfc4340</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4732">[RFC4732]</dt>
        <dd>
<span class="refAuthor">Handley, M., Ed.</span>, <span class="refAuthor">Rescorla, E., Ed.</span>, and <span class="refAuthor">IAB</span>, <span class="refTitle">"Internet Denial-of-Service Considerations"</span>, <span class="seriesInfo">RFC 4732</span>, <span class="seriesInfo">DOI 10.17487/RFC4732</span>, <time datetime="2006-12" class="refDate">December 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4732">https://www.rfc-editor.org/info/rfc4732</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4787">[RFC4787]</dt>
        <dd>
<span class="refAuthor">Audet, F., Ed.</span> and <span class="refAuthor">C. Jennings</span>, <span class="refTitle">"Network Address Translation (NAT) Behavioral Requirements for Unicast UDP"</span>, <span class="seriesInfo">BCP 127</span>, <span class="seriesInfo">RFC 4787</span>, <span class="seriesInfo">DOI 10.17487/RFC4787</span>, <time datetime="2007-01" class="refDate">January 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4787">https://www.rfc-editor.org/info/rfc4787</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4960">[RFC4960]</dt>
        <dd>
<span class="refAuthor">Stewart, R., Ed.</span>, <span class="refTitle">"Stream Control Transmission Protocol"</span>, <span class="seriesInfo">RFC 4960</span>, <span class="seriesInfo">DOI 10.17487/RFC4960</span>, <time datetime="2007-09" class="refDate">September 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4960">https://www.rfc-editor.org/info/rfc4960</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4987">[RFC4987]</dt>
        <dd>
<span class="refAuthor">Eddy, W.</span>, <span class="refTitle">"TCP SYN Flooding Attacks and Common Mitigations"</span>, <span class="seriesInfo">RFC 4987</span>, <span class="seriesInfo">DOI 10.17487/RFC4987</span>, <time datetime="2007-08" class="refDate">August 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4987">https://www.rfc-editor.org/info/rfc4987</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5925">[RFC5925]</dt>
        <dd>
<span class="refAuthor">Touch, J.</span>, <span class="refAuthor">Mankin, A.</span>, and <span class="refAuthor">R. Bonica</span>, <span class="refTitle">"The TCP Authentication Option"</span>, <span class="seriesInfo">RFC 5925</span>, <span class="seriesInfo">DOI 10.17487/RFC5925</span>, <time datetime="2010-06" class="refDate">June 2010</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5925">https://www.rfc-editor.org/info/rfc5925</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6052">[RFC6052]</dt>
        <dd>
<span class="refAuthor">Bao, C.</span>, <span class="refAuthor">Huitema, C.</span>, <span class="refAuthor">Bagnulo, M.</span>, <span class="refAuthor">Boucadair, M.</span>, and <span class="refAuthor">X. Li</span>, <span class="refTitle">"IPv6 Addressing of IPv4/IPv6 Translators"</span>, <span class="seriesInfo">RFC 6052</span>, <span class="seriesInfo">DOI 10.17487/RFC6052</span>, <time datetime="2010-10" class="refDate">October 2010</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6052">https://www.rfc-editor.org/info/rfc6052</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6146">[RFC6146]</dt>
        <dd>
<span class="refAuthor">Bagnulo, M.</span>, <span class="refAuthor">Matthews, P.</span>, and <span class="refAuthor">I. van Beijnum</span>, <span class="refTitle">"Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers"</span>, <span class="seriesInfo">RFC 6146</span>, <span class="seriesInfo">DOI 10.17487/RFC6146</span>, <time datetime="2011-04" class="refDate">April 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6146">https://www.rfc-editor.org/info/rfc6146</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6234">[RFC6234]</dt>
        <dd>
<span class="refAuthor">Eastlake 3rd, D.</span> and <span class="refAuthor">T. Hansen</span>, <span class="refTitle">"US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)"</span>, <span class="seriesInfo">RFC 6234</span>, <span class="seriesInfo">DOI 10.17487/RFC6234</span>, <time datetime="2011-05" class="refDate">May 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6234">https://www.rfc-editor.org/info/rfc6234</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6296">[RFC6296]</dt>
        <dd>
<span class="refAuthor">Wasserman, M.</span> and <span class="refAuthor">F. Baker</span>, <span class="refTitle">"IPv6-to-IPv6 Network Prefix Translation"</span>, <span class="seriesInfo">RFC 6296</span>, <span class="seriesInfo">DOI 10.17487/RFC6296</span>, <time datetime="2011-06" class="refDate">June 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6296">https://www.rfc-editor.org/info/rfc6296</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6724">[RFC6724]</dt>
        <dd>
<span class="refAuthor">Thaler, D., Ed.</span>, <span class="refAuthor">Draves, R.</span>, <span class="refAuthor">Matsumoto, A.</span>, and <span class="refAuthor">T. Chown</span>, <span class="refTitle">"Default Address Selection for Internet Protocol Version 6 (IPv6)"</span>, <span class="seriesInfo">RFC 6724</span>, <span class="seriesInfo">DOI 10.17487/RFC6724</span>, <time datetime="2012-09" class="refDate">September 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6724">https://www.rfc-editor.org/info/rfc6724</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6838">[RFC6838]</dt>
        <dd>
<span class="refAuthor">Freed, N.</span>, <span class="refAuthor">Klensin, J.</span>, and <span class="refAuthor">T. Hansen</span>, <span class="refTitle">"Media Type Specifications and Registration Procedures"</span>, <span class="seriesInfo">BCP 13</span>, <span class="seriesInfo">RFC 6838</span>, <span class="seriesInfo">DOI 10.17487/RFC6838</span>, <time datetime="2013-01" class="refDate">January 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6838">https://www.rfc-editor.org/info/rfc6838</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6887">[RFC6887]</dt>
        <dd>
<span class="refAuthor">Wing, D., Ed.</span>, <span class="refAuthor">Cheshire, S.</span>, <span class="refAuthor">Boucadair, M.</span>, <span class="refAuthor">Penno, R.</span>, and <span class="refAuthor">P. Selkirk</span>, <span class="refTitle">"Port Control Protocol (PCP)"</span>, <span class="seriesInfo">RFC 6887</span>, <span class="seriesInfo">DOI 10.17487/RFC6887</span>, <time datetime="2013-04" class="refDate">April 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6887">https://www.rfc-editor.org/info/rfc6887</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6888">[RFC6888]</dt>
        <dd>
<span class="refAuthor">Perreault, S., Ed.</span>, <span class="refAuthor">Yamagata, I.</span>, <span class="refAuthor">Miyakawa, S.</span>, <span class="refAuthor">Nakagawa, A.</span>, and <span class="refAuthor">H. Ashida</span>, <span class="refTitle">"Common Requirements for Carrier-Grade NATs (CGNs)"</span>, <span class="seriesInfo">BCP 127</span>, <span class="seriesInfo">RFC 6888</span>, <span class="seriesInfo">DOI 10.17487/RFC6888</span>, <time datetime="2013-04" class="refDate">April 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6888">https://www.rfc-editor.org/info/rfc6888</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7030">[RFC7030]</dt>
        <dd>
<span class="refAuthor">Pritikin, M., Ed.</span>, <span class="refAuthor">Yee, P., Ed.</span>, and <span class="refAuthor">D. Harkins, Ed.</span>, <span class="refTitle">"Enrollment over Secure Transport"</span>, <span class="seriesInfo">RFC 7030</span>, <span class="seriesInfo">DOI 10.17487/RFC7030</span>, <time datetime="2013-10" class="refDate">October 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7030">https://www.rfc-editor.org/info/rfc7030</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7413">[RFC7413]</dt>
        <dd>
<span class="refAuthor">Cheng, Y.</span>, <span class="refAuthor">Chu, J.</span>, <span class="refAuthor">Radhakrishnan, S.</span>, and <span class="refAuthor">A. Jain</span>, <span class="refTitle">"TCP Fast Open"</span>, <span class="seriesInfo">RFC 7413</span>, <span class="seriesInfo">DOI 10.17487/RFC7413</span>, <time datetime="2014-12" class="refDate">December 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7413">https://www.rfc-editor.org/info/rfc7413</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7452">[RFC7452]</dt>
        <dd>
<span class="refAuthor">Tschofenig, H.</span>, <span class="refAuthor">Arkko, J.</span>, <span class="refAuthor">Thaler, D.</span>, and <span class="refAuthor">D. McPherson</span>, <span class="refTitle">"Architectural Considerations in Smart Object Networking"</span>, <span class="seriesInfo">RFC 7452</span>, <span class="seriesInfo">DOI 10.17487/RFC7452</span>, <time datetime="2015-03" class="refDate">March 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7452">https://www.rfc-editor.org/info/rfc7452</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7589">[RFC7589]</dt>
        <dd>
<span class="refAuthor">Badra, M.</span>, <span class="refAuthor">Luchuk, A.</span>, and <span class="refAuthor">J. Schoenwaelder</span>, <span class="refTitle">"Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"</span>, <span class="seriesInfo">RFC 7589</span>, <span class="seriesInfo">DOI 10.17487/RFC7589</span>, <time datetime="2015-06" class="refDate">June 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7589">https://www.rfc-editor.org/info/rfc7589</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7858">[RFC7858]</dt>
        <dd>
<span class="refAuthor">Hu, Z.</span>, <span class="refAuthor">Zhu, L.</span>, <span class="refAuthor">Heidemann, J.</span>, <span class="refAuthor">Mankin, A.</span>, <span class="refAuthor">Wessels, D.</span>, and <span class="refAuthor">P. Hoffman</span>, <span class="refTitle">"Specification for DNS over Transport Layer Security (TLS)"</span>, <span class="seriesInfo">RFC 7858</span>, <span class="seriesInfo">DOI 10.17487/RFC7858</span>, <time datetime="2016-05" class="refDate">May 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7858">https://www.rfc-editor.org/info/rfc7858</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7951">[RFC7951]</dt>
        <dd>
<span class="refAuthor">Lhotka, L.</span>, <span class="refTitle">"JSON Encoding of Data Modeled with YANG"</span>, <span class="seriesInfo">RFC 7951</span>, <span class="seriesInfo">DOI 10.17487/RFC7951</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7951">https://www.rfc-editor.org/info/rfc7951</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8340">[RFC8340]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span> and <span class="refAuthor">L. Berger, Ed.</span>, <span class="refTitle">"YANG Tree Diagrams"</span>, <span class="seriesInfo">BCP 215</span>, <span class="seriesInfo">RFC 8340</span>, <span class="seriesInfo">DOI 10.17487/RFC8340</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8340">https://www.rfc-editor.org/info/rfc8340</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8484">[RFC8484]</dt>
        <dd>
<span class="refAuthor">Hoffman, P.</span> and <span class="refAuthor">P. McManus</span>, <span class="refTitle">"DNS Queries over HTTPS (DoH)"</span>, <span class="seriesInfo">RFC 8484</span>, <span class="seriesInfo">DOI 10.17487/RFC8484</span>, <time datetime="2018-10" class="refDate">October 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8484">https://www.rfc-editor.org/info/rfc8484</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8489">[RFC8489]</dt>
        <dd>
<span class="refAuthor">Petit-Huguenin, M.</span>, <span class="refAuthor">Salgueiro, G.</span>, <span class="refAuthor">Rosenberg, J.</span>, <span class="refAuthor">Wing, D.</span>, <span class="refAuthor">Mahy, R.</span>, and <span class="refAuthor">P. Matthews</span>, <span class="refTitle">"Session Traversal Utilities for NAT (STUN)"</span>, <span class="seriesInfo">RFC 8489</span>, <span class="seriesInfo">DOI 10.17487/RFC8489</span>, <time datetime="2020-02" class="refDate">February 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8489">https://www.rfc-editor.org/info/rfc8489</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8499">[RFC8499]</dt>
        <dd>
<span class="refAuthor">Hoffman, P.</span>, <span class="refAuthor">Sullivan, A.</span>, and <span class="refAuthor">K. Fujiwara</span>, <span class="refTitle">"DNS Terminology"</span>, <span class="seriesInfo">BCP 219</span>, <span class="seriesInfo">RFC 8499</span>, <span class="seriesInfo">DOI 10.17487/RFC8499</span>, <time datetime="2019-01" class="refDate">January 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8499">https://www.rfc-editor.org/info/rfc8499</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8612">[RFC8612]</dt>
        <dd>
<span class="refAuthor">Mortensen, A.</span>, <span class="refAuthor">Reddy, T.</span>, and <span class="refAuthor">R. Moskowitz</span>, <span class="refTitle">"DDoS Open Threat Signaling (DOTS) Requirements"</span>, <span class="seriesInfo">RFC 8612</span>, <span class="seriesInfo">DOI 10.17487/RFC8612</span>, <time datetime="2019-05" class="refDate">May 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8612">https://www.rfc-editor.org/info/rfc8612</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8782">[RFC8782]</dt>
        <dd>
<span class="refAuthor">Reddy.K, T., Ed.</span>, <span class="refAuthor">Boucadair, M., Ed.</span>, <span class="refAuthor">Patil, P.</span>, <span class="refAuthor">Mortensen, A.</span>, and <span class="refAuthor">N. Teague</span>, <span class="refTitle">"Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel Specification"</span>, <span class="seriesInfo">RFC 8782</span>, <span class="seriesInfo">DOI 10.17487/RFC8782</span>, <time datetime="2020-05" class="refDate">May 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8782">https://www.rfc-editor.org/info/rfc8782</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8811">[RFC8811]</dt>
        <dd>
<span class="refAuthor">Mortensen, A., Ed.</span>, <span class="refAuthor">Reddy.K, T., Ed.</span>, <span class="refAuthor">Andreasen, F.</span>, <span class="refAuthor">Teague, N.</span>, and <span class="refAuthor">R. Compton</span>, <span class="refTitle">"DDoS Open Threat Signaling (DOTS) Architecture"</span>, <span class="seriesInfo">RFC 8811</span>, <span class="seriesInfo">DOI 10.17487/RFC8811</span>, <time datetime="2020-08" class="refDate">August 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8811">https://www.rfc-editor.org/info/rfc8811</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8903">[RFC8903]</dt>
        <dd>
<span class="refAuthor">Dobbins, R.</span>, <span class="refAuthor">Migault, D.</span>, <span class="refAuthor">Moskowitz, R.</span>, <span class="refAuthor">Teague, N.</span>, <span class="refAuthor">Xia, L.</span>, and <span class="refAuthor">K. Nishizuka</span>, <span class="refTitle">"Use Cases for DDoS Open Threat Signaling"</span>, <span class="seriesInfo">RFC 8903</span>, <span class="seriesInfo">DOI 10.17487/RFC8903</span>, <time datetime="2021-05" class="refDate">May 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8903">https://www.rfc-editor.org/info/rfc8903</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8973">[RFC8973]</dt>
        <dd>
<span class="refAuthor">Boucadair, M.</span> and <span class="refAuthor">T. Reddy.K</span>, <span class="refTitle">"DDoS Open Threat Signaling (DOTS) Agent Discovery"</span>, <span class="seriesInfo">RFC 8973</span>, <span class="seriesInfo">DOI 10.17487/RFC8973</span>, <time datetime="2021-01" class="refDate">January 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8973">https://www.rfc-editor.org/info/rfc8973</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.ietf-tls-dtls13">[TLS-DTLS13]</dt>
        <dd>
<span class="refAuthor">Rescorla, E.</span>, <span class="refAuthor">Tschofenig, H.</span>, and <span class="refAuthor">N. Modadugu</span>, <span class="refTitle">"The Datagram Transport Layer Security (DTLS) Protocol Version 1.3"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-tls-dtls13-43</span>, <time datetime="2021-04-30" class="refDate">30 April 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-tls-dtls13-43">https://datatracker.ietf.org/doc/html/draft-ietf-tls-dtls13-43</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="URI">[URI]</dt>
      <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Well-Known URIs"</span>, <span>&lt;<a href="https://www.iana.org/assignments/well-known-uris">https://www.iana.org/assignments/well-known-uris</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="changes">
<section id="appendix-A">
      <h2 id="name-summary-of-changes-from-rfc">
<a href="#appendix-A" class="section-number selfRef">Appendix A. </a><a href="#name-summary-of-changes-from-rfc" class="section-name selfRef">Summary of Changes From RFC 8782</a>
      </h2>
<p id="appendix-A-1">The main changes compared to <span>[<a href="#RFC8782" class="xref">RFC8782</a>]</span> are as
      follows:<a href="#appendix-A-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="appendix-A-2.1">
          <p id="appendix-A-2.1.1">Update the "ietf-dots-signal-channel" YANG module (<a href="#yrequest" class="xref">Section 5.3</a>) and the tree structure (<a href="#tree" class="xref">Section 5.1</a>) to follow the new YANG data structure
          specified in <span>[<a href="#RFC8791" class="xref">RFC8791</a>]</span>. In particular:<a href="#appendix-A-2.1.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="appendix-A-2.1.2.1">Add in 'choice' to indicate the communication direction in
              which a data node applies. If no 'choice' is indicated, a data
              node can appear in both directions (i.e., from DOTS clients to
              DOTS servers and vice versa).<a href="#appendix-A-2.1.2.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="appendix-A-2.1.2.2">Remove 'config' clauses. Note that 'config' statements will
              be ignored (if present) anyway, according to <span><a href="https://www.rfc-editor.org/rfc/rfc8791#section-4" class="relref">Section 4</a> of [<a href="#RFC8791" class="xref">RFC8791</a>]</span>. This supersedes the references to the
              use of 'ro' and 'rw', which are now covered by 'choice'
              above.<a href="#appendix-A-2.1.2.2" class="pilcrow">¶</a>
</li>
            <li class="normal" id="appendix-A-2.1.2.3">Remove 'cuid', 'cdid', and 'sid' data nodes from the
              structure because these data nodes are included as Uri-Path
              options, not within the message body.<a href="#appendix-A-2.1.2.3" class="pilcrow">¶</a>
</li>
            <li class="normal" id="appendix-A-2.1.2.4">Remove the list keys for the mitigation scope message type
              (i.e., 'cuid' and 'mid'). 'mid' is not indicated as a key
              because it is included as a Uri-Path option for requests and in
              the message body for responses. Note that <span><a href="https://www.rfc-editor.org/rfc/rfc8791#section-4" class="relref">Section 4</a> of [<a href="#RFC8791" class="xref">RFC8791</a>]</span> specifies that a list does not require
              to have a key statement defined.<a href="#appendix-A-2.1.2.4" class="pilcrow">¶</a>
</li>
          </ul>
</li>
        <li class="normal" id="appendix-A-2.2">Add a new section with a summary of the error code responses that
          can be returned by a DOTS server (<a href="#errors" class="xref">Section 9</a>).<a href="#appendix-A-2.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-A-2.3">Update the IANA section to allocate a new range for
          comprehension-optional attributes (<a href="#format" class="xref">Section 10.6.1.1</a>).
          This modification is motivated by the need to allow for compact DOTS
          signal messages that include a long list of comprehension-optional
          attributes, e.g., DOTS telemetry messages <span>[<a href="#I-D.ietf-dots-telemetry" class="xref">DOTS-TELEMETRY</a>]</span>.<a href="#appendix-A-2.3" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-A-2.4">Add <a href="#def" class="xref">Appendix C</a> to list recommended/default values
          of key DOTS signal channel parameters.<a href="#appendix-A-2.4" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-A-2.5">Add subsections to <a href="#post" class="xref">Section 4.4.1</a> for better
 readability.<a href="#appendix-A-2.5" class="pilcrow">¶</a>
</li>
      </ul>
</section>
</div>
<div id="motiv">
<section id="appendix-B">
      <h2 id="name-cuid-generation">
<a href="#appendix-B" class="section-number selfRef">Appendix B. </a><a href="#name-cuid-generation" class="section-name selfRef">CUID Generation</a>
      </h2>
<p id="appendix-B-1">The document recommends the use of SPKI to generate the 'cuid'. This
      design choice is motivated by the following reasons:<a href="#appendix-B-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="appendix-B-2.1">SPKI is globally unique.<a href="#appendix-B-2.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-B-2.2">It is deterministic.<a href="#appendix-B-2.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-B-2.3">It allows the avoidance of extra cycles that may be induced by
          'cuid' collision.<a href="#appendix-B-2.3" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-B-2.4">DOTS clients do not need to store the 'cuid' in a persistent
          storage.<a href="#appendix-B-2.4" class="pilcrow">¶</a>
</li>
        <li class="normal" id="appendix-B-2.5">It allows the detection of compromised DOTS clients that do not
          adhere to the 'cuid' generation algorithm.<a href="#appendix-B-2.5" class="pilcrow">¶</a>
</li>
      </ul>
</section>
</div>
<div id="def">
<section id="appendix-C">
      <h2 id="name-summary-of-protocol-recomme">
<a href="#appendix-C" class="section-number selfRef">Appendix C. </a><a href="#name-summary-of-protocol-recomme" class="section-name selfRef">Summary of Protocol Recommended/Default Values</a>
      </h2>
<table class="center" id="table-13">
        <caption><a href="#table-13" class="selfRef">Table 13</a></caption>
<thead>
          <tr>
            <th class="text-left" rowspan="1" colspan="1">Parameter</th>
            <th class="text-left" rowspan="1" colspan="1">Recommended/Default Value</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">Port number</td>
            <td class="text-left" rowspan="1" colspan="1">4646 (tcp/udp)</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">lifetime</td>
            <td class="text-left" rowspan="1" colspan="1">3600 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">active-but-terminating</td>
            <td class="text-left" rowspan="1" colspan="1">120 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">maximum active-but-terminating</td>
            <td class="text-left" rowspan="1" colspan="1">300 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">heartbeat-interval</td>
            <td class="text-left" rowspan="1" colspan="1">30 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">minimum 'heartbeat-interval'</td>
            <td class="text-left" rowspan="1" colspan="1">15 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">maximum 'heartbeat-interval'</td>
            <td class="text-left" rowspan="1" colspan="1">240 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">missing-hb-allowed</td>
            <td class="text-left" rowspan="1" colspan="1">15</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">max-retransmit</td>
            <td class="text-left" rowspan="1" colspan="1">3</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ack-timeout</td>
            <td class="text-left" rowspan="1" colspan="1">2 seconds</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">ack-random-factor</td>
            <td class="text-left" rowspan="1" colspan="1">1.5</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">probing-rate</td>
            <td class="text-left" rowspan="1" colspan="1">5 bytes/second</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">trigger-mitigation</td>
            <td class="text-left" rowspan="1" colspan="1">true</td>
          </tr>
        </tbody>
      </table>
</section>
</div>
<div id="ack">
<section id="appendix-D">
      <h2 id="name-acknowledgements">
<a href="#name-acknowledgements" class="section-name selfRef">Acknowledgements</a>
      </h2>
<p id="appendix-D-1">Many thanks to <span class="contact-name">Martin Björklund</span> for the suggestion to use
      <span>[<a href="#RFC8791" class="xref">RFC8791</a>]</span>.<a href="#appendix-D-1" class="pilcrow">¶</a></p>
<p id="appendix-D-2">Thanks to <span class="contact-name">Valery Smyslov</span> for the comments, guidance, and
      support.<a href="#appendix-D-2" class="pilcrow">¶</a></p>
<p id="appendix-D-3">Thanks to <span class="contact-name">Ebben Aries</span> for the yangdoctors review, 
      <span class="contact-name">Dan Romascanu</span> for
      the opsdir review, <span class="contact-name">Michael Tuexen</span> for the tsv-art review, 
      <span class="contact-name">Dale Worley</span>
      for the genart review, and <span class="contact-name">Donald Eastlake 3rd</span> for the secdir
      review.<a href="#appendix-D-3" class="pilcrow">¶</a></p>
<p id="appendix-D-4">Thanks to <span class="contact-name">Benjamin Kaduk</span> for the AD review.<a href="#appendix-D-4" class="pilcrow">¶</a></p>
<p id="appendix-D-5">Thanks to <span class="contact-name">Martin Duke</span>, <span class="contact-name">Lars Eggert</span>, 
      <span class="contact-name">Erik Kline</span>, <span class="contact-name">Murray Kucherawy</span>,
      <span class="contact-name">Éric Vyncke</span>, and <span class="contact-name">Robert Wilton</span> 
      for the IESG review.<a href="#appendix-D-5" class="pilcrow">¶</a></p>
<section id="appendix-D.1">
        <h3 id="name-acknowledgements-from-rfc-8">
<a href="#name-acknowledgements-from-rfc-8" class="section-name selfRef">Acknowledgements from RFC 8782</a>
        </h3>
<p id="appendix-D.1-1">Thanks to <span class="contact-name">Christian Jacquenet</span>, <span class="contact-name">Roland Dobbins</span>, <span class="contact-name">Roman Danyliw</span>,
        <span class="contact-name">Michael Richardson</span>, <span class="contact-name">Ehud Doron</span>, 
 <span class="contact-name">Kaname Nishizuka</span>, <span class="contact-name">Dave Dolson</span>, 
 <span class="contact-name">Liang Xia</span>, <span class="contact-name">Gilbert Clark</span>, 
 <span class="contact-name">Xialiang Frank</span>, <span class="contact-name">Jim Schaad</span>, 
 <span class="contact-name">Klaus Hartke</span>, <span class="contact-name">Nesredien Suleiman</span>, 
 <span class="contact-name">Stephen Farrell</span>, and <span class="contact-name">Yoshifumi Nishida</span> 
 for the discussion and comments.<a href="#appendix-D.1-1" class="pilcrow">¶</a></p>
<p id="appendix-D.1-2">The authors would like to give special thanks to <span class="contact-name">Kaname Nishizuka</span> and <span class="contact-name">Jon Shallow</span> 
 for their efforts in implementing the protocol and
        performing interop testing at IETF Hackathons.<a href="#appendix-D.1-2" class="pilcrow">¶</a></p>
<p id="appendix-D.1-3">Thanks to the core WG for the recommendations on Hop-Limit and
        redirect signaling.<a href="#appendix-D.1-3" class="pilcrow">¶</a></p>
<p id="appendix-D.1-4">Special thanks to <span class="contact-name">Benjamin Kaduk</span> for the detailed AD review.<a href="#appendix-D.1-4" class="pilcrow">¶</a></p>
<p id="appendix-D.1-5">Thanks to <span class="contact-name">Alexey Melnikov</span>, <span class="contact-name">Adam Roach</span>,
 <span class="contact-name">Suresh Krishnan</span>, <span class="contact-name">Mirja Kuehlewind</span>, and
 <span class="contact-name">Alissa Cooper</span> for the review.<a href="#appendix-D.1-5" class="pilcrow">¶</a></p>
<p id="appendix-D.1-6">Thanks to <span class="contact-name">Carsten Bormann</span> for his review of the DOTS heartbeat
        mechanism.<a href="#appendix-D.1-6" class="pilcrow">¶</a></p>
</section>
</section>
</div>
<div id="contr">
<section id="appendix-E">
      <h2 id="name-contributors">
<a href="#name-contributors" class="section-name selfRef">Contributors</a>
      </h2>
<p id="appendix-E-1">The authors of RFC 8782 are listed below:<a href="#appendix-E-1" class="pilcrow">¶</a></p>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Tirumaleswar Reddy.K (editor)</span></div>
<div dir="auto" class="left"><span class="org">McAfee, Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">Embassy Golf Link Business Park</span></div>
<div dir="auto" class="left">
<span class="locality">Bangalore</span> <span class="postal-code">560071</span>
</div>
<div dir="auto" class="left"><span class="region">Karnataka</span></div>
<div dir="auto" class="left"><span class="country-name">India</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:kondtir@gmail.com" class="email">kondtir@gmail.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Mohamed Boucadair (editor)</span></div>
<div dir="auto" class="left"><span class="org">Orange</span></div>
<div dir="auto" class="left">
<span class="postal-code">35000</span> <span class="locality">Rennes</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:mohamed.boucadair@orange.com" class="email">mohamed.boucadair@orange.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Prashanth Patil</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:praspati@cisco.com" class="email">praspati@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Andrew Mortensen</span></div>
<div dir="auto" class="left"><span class="org">Arbor Networks, Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">2727 S. State Street</span></div>
<div dir="auto" class="left">
<span class="locality">Ann Arbor</span>, <span class="region">MI</span> <span class="postal-code">48104</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:andrew@moretension.com" class="email">andrew@moretension.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Nik Teague</span></div>
<div dir="auto" class="left"><span class="org">Iron Mountain Data Centers</span></div>
<div dir="auto" class="left"><span class="country-name">United Kingdom</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:nteague@ironmountain.co.uk" class="email">nteague@ironmountain.co.uk</a>
</div>
</address>
<p id="appendix-E-2">The following individuals have contributed to RFC 8782:<a href="#appendix-E-2" class="pilcrow">¶</a></p>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Jon Shallow</span></div>
<div dir="auto" class="left"><span class="org">NCC Group</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:jon.shallow@nccgroup.trust" class="email">jon.shallow@nccgroup.trust</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Mike Geller</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div dir="auto" class="left">
<span class="region">FL</span> <span class="postal-code">33309</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:mgeller@cisco.com" class="email">mgeller@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Robert Moskowitz</span></div>
<div dir="auto" class="left"><span class="org">HTT Consulting</span></div>
<div dir="auto" class="left">
<span class="locality">Oak Park</span>, <span class="region">MI</span> <span class="postal-code">42837</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:rgm@htt-consult.com" class="email">rgm@htt-consult.com</a>
</div>
</address>
</section>
</div>
<div id="authors-addresses">
<section id="appendix-F">
      <h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Mohamed Boucadair (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Orange</span></div>
<div dir="auto" class="left">
<span class="postal-code">35000</span> <span class="locality">Rennes</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:mohamed.boucadair@orange.com" class="email">mohamed.boucadair@orange.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Jon Shallow</span></div>
<div dir="auto" class="left"><span class="country-name">United Kingdom</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:supjps-ietf@jpshallow.com" class="email">supjps-ietf@jpshallow.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Tirumaleswar Reddy.K</span></div>
<div dir="auto" class="left"><span class="org">Akamai</span></div>
<div dir="auto" class="left"><span class="street-address">Embassy Golf Link Business Park</span></div>
<div dir="auto" class="left">
<span class="locality">Bangalore</span> <span class="postal-code">560071</span>
</div>
<div dir="auto" class="left"><span class="region">Karnataka</span></div>
<div dir="auto" class="left"><span class="country-name">India</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:kondtir@gmail.com" class="email">kondtir@gmail.com</a>
</div>
</address>
</section>
</div>
<script>const toc = document.getElementById("toc");
toc.querySelector("h2").addEventListener("click", e => {
  toc.classList.toggle("active");
});
toc.querySelector("nav").addEventListener("click", e => {
  toc.classList.remove("active");
});
</script>
</body>
</html>