File: rfc8801.html

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<!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 8801: Discovering Provisioning Domain Names and Data</title>
<meta content="Pierre Pfister" name="author">
<meta content="Éric Vyncke" name="author">
<meta content="Tommy Pauly" name="author">
<meta content="David Schinazi" name="author">
<meta content="Wenqin Shao" name="author">
<meta content="
       Provisioning Domains (PvDs) are defined as consistent
sets of network configuration information. PvDs allows hosts to manage
connections to multiple networks and interfaces simultaneously, such as
when a home router provides connectivity through both a broadband and
cellular network provider. 
       This document defines a mechanism for explicitly identifying PvDs
      through
a Router Advertisement (RA) option. This RA option announces a PvD identifier,
which hosts can compare to differentiate between PvDs. The option can directly
carry some information about a PvD and can optionally point to
PvD Additional Information that can be retrieved using HTTP over TLS. 
    " name="description">
<meta content="xml2rfc 2.47.0" name="generator">
<meta content="IPv6" name="keyword">
<meta content="Provisioning" name="keyword">
<meta content="DHCP" name="keyword">
<meta content="PvD" name="keyword">
<meta content="8801" name="rfc.number">
<link href="rfc8801.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.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 {
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<link href="https://dx.doi.org/10.17487/rfc8801" rel="alternate">
  <link href="urn:issn:2070-1721" rel="alternate">
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<table class="ears">
<thead><tr>
<td class="left">RFC 8801</td>
<td class="center">Provisioning Domains</td>
<td class="right">July 2020</td>
</tr></thead>
<tfoot><tr>
<td class="left">Pfister, 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/rfc8801" class="eref">8801</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="2020-07" class="published">July 2020</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">P. Pfister</div>
<div class="org">Cisco</div>
</div>
<div class="author">
      <div class="author-name">É. Vyncke</div>
<div class="org">Cisco</div>
</div>
<div class="author">
      <div class="author-name">T. Pauly</div>
<div class="org">Apple Inc.</div>
</div>
<div class="author">
      <div class="author-name">D. Schinazi</div>
<div class="org">Google LLC</div>
</div>
<div class="author">
      <div class="author-name">W. Shao</div>
<div class="org">Cisco</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 8801</h1>
<h1 id="title">Discovering Provisioning Domain Names and Data</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">Provisioning Domains (PvDs) are defined as consistent
sets of network configuration information. PvDs allows hosts to manage
connections to multiple networks and interfaces simultaneously, such as
when a home router provides connectivity through both a broadband and
cellular network provider.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
<p id="section-abstract-2">This document defines a mechanism for explicitly identifying PvDs
      through
a Router Advertisement (RA) option. This RA option announces a PvD identifier,
which hosts can compare to differentiate between PvDs. The option can directly
carry some information about a PvD and can optionally point to
PvD Additional Information that can be retrieved using HTTP over TLS.<a href="#section-abstract-2" 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>
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            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/rfc8801">https://www.rfc-editor.org/info/rfc8801</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
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<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
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            This document is subject to BCP 78 and the IETF Trust's Legal
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            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 compact">
<li class="toc ulEmpty 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><a href="#section-toc.1-1.1.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.1.2.1">
                <p id="section-toc.1-1.1.2.1.1" class="keepWithNext"><a href="#section-1.1" class="xref">1.1</a>.  <a href="#name-specification-of-requiremen" class="xref">Specification of Requirements</a><a href="#section-toc.1-1.1.2.1.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty 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><a href="#section-toc.1-1.2.1" class="pilcrow">¶</a></p>
</li>
          <li class="toc ulEmpty 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-provisioning-domain-identif" class="xref">Provisioning Domain Identification Using Router
      Advertisements</a><a href="#section-toc.1-1.3.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.3.2.1">
                <p id="section-toc.1-1.3.2.1.1"><a href="#section-3.1" class="xref">3.1</a>.  <a href="#name-pvd-option-for-router-adver" class="xref">PvD Option for Router Advertisements</a><a href="#section-toc.1-1.3.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.2">
                <p id="section-toc.1-1.3.2.2.1"><a href="#section-3.2" class="xref">3.2</a>.  <a href="#name-router-behavior" class="xref">Router Behavior</a><a href="#section-toc.1-1.3.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.3">
                <p id="section-toc.1-1.3.2.3.1"><a href="#section-3.3" class="xref">3.3</a>.  <a href="#name-non-pvd-aware-host-behavior" class="xref">Non-PvD-Aware Host Behavior</a><a href="#section-toc.1-1.3.2.3.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.4">
                <p id="section-toc.1-1.3.2.4.1"><a href="#section-3.4" class="xref">3.4</a>.  <a href="#name-pvd-aware-host-behavior" class="xref">PvD-Aware Host Behavior</a><a href="#section-toc.1-1.3.2.4.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.3.2.4.2.1">
                    <p id="section-toc.1-1.3.2.4.2.1.1"><a href="#section-3.4.1" class="xref">3.4.1</a>.  <a href="#name-dhcpv6-configuration-associ" class="xref">DHCPv6 Configuration Association</a><a href="#section-toc.1-1.3.2.4.2.1.1" class="pilcrow">¶</a></p>
</li>
                  <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.4.2.2">
                    <p id="section-toc.1-1.3.2.4.2.2.1"><a href="#section-3.4.2" class="xref">3.4.2</a>.  <a href="#name-dhcpv4-configuration-associ" class="xref">DHCPv4 Configuration Association</a><a href="#section-toc.1-1.3.2.4.2.2.1" class="pilcrow">¶</a></p>
</li>
                  <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.4.2.3">
                    <p id="section-toc.1-1.3.2.4.2.3.1"><a href="#section-3.4.3" class="xref">3.4.3</a>.  <a href="#name-connection-sharing-by-the-h" class="xref">Connection Sharing by the Host</a><a href="#section-toc.1-1.3.2.4.2.3.1" class="pilcrow">¶</a></p>
</li>
                  <li class="toc ulEmpty compact" id="section-toc.1-1.3.2.4.2.4">
                    <p id="section-toc.1-1.3.2.4.2.4.1"><a href="#section-3.4.4" class="xref">3.4.4</a>.  <a href="#name-usage-of-dns-servers" class="xref">Usage of DNS Servers</a><a href="#section-toc.1-1.3.2.4.2.4.1" class="pilcrow">¶</a></p>
</li>
                </ul>
</li>
            </ul>
</li>
          <li class="toc ulEmpty 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-provisioning-domain-additio" class="xref">Provisioning Domain Additional Information</a><a href="#section-toc.1-1.4.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty 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-retrieving-the-pvd-addition" class="xref">Retrieving the PvD Additional Information</a><a href="#section-toc.1-1.4.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty 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-operational-consideration-t" class="xref">Operational Consideration to Providing the PvD Additional
 Information</a><a href="#section-toc.1-1.4.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty 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-pvd-additional-information-" class="xref">PvD Additional Information Format</a><a href="#section-toc.1-1.4.2.3.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.4.2.3.2.1">
                    <p id="section-toc.1-1.4.2.3.2.1.1"><a href="#section-4.3.1" class="xref">4.3.1</a>.  <a href="#name-example" class="xref">Example</a><a href="#section-toc.1-1.4.2.3.2.1.1" class="pilcrow">¶</a></p>
</li>
                </ul>
</li>
              <li class="toc ulEmpty 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-detecting-misconfiguration-" class="xref">Detecting Misconfiguration and Misuse</a><a href="#section-toc.1-1.4.2.4.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty 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-operational-considerations" class="xref">Operational Considerations</a><a href="#section-toc.1-1.5.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty 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-exposing-extra-ra-options-t" class="xref">Exposing Extra RA Options to PvD-Aware Hosts</a><a href="#section-toc.1-1.5.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty 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-different-ras-for-pvd-aware" class="xref">Different RAs for PvD-Aware and Non-PvD-Aware Hosts</a><a href="#section-toc.1-1.5.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty 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-enabling-multihoming-for-pv" class="xref">Enabling Multihoming for PvD-Aware Hosts</a><a href="#section-toc.1-1.5.2.3.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.5.2.4">
                <p id="section-toc.1-1.5.2.4.1"><a href="#section-5.4" class="xref">5.4</a>.  <a href="#name-providing-additional-inform" class="xref">Providing Additional Information to PvD-Aware Hosts</a><a href="#section-toc.1-1.5.2.4.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty 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-security-considerations" class="xref">Security Considerations</a><a href="#section-toc.1-1.6.1" class="pilcrow">¶</a></p>
</li>
          <li class="toc ulEmpty 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-privacy-considerations" class="xref">Privacy Considerations</a><a href="#section-toc.1-1.7.1" class="pilcrow">¶</a></p>
</li>
          <li class="toc ulEmpty 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-iana-considerations" class="xref">IANA Considerations</a><a href="#section-toc.1-1.8.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.8.2.1">
                <p id="section-toc.1-1.8.2.1.1"><a href="#section-8.1" class="xref">8.1</a>.  <a href="#name-change-to-ipv6-neighbor-dis" class="xref">Change to IPv6 Neighbor Discovery Option Formats Registry</a><a href="#section-toc.1-1.8.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.8.2.2">
                <p id="section-toc.1-1.8.2.2.1"><a href="#section-8.2" class="xref">8.2</a>.  <a href="#name-new-entry-in-the-well-known" class="xref">New Entry in the Well-Known URIs Registry</a><a href="#section-toc.1-1.8.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.8.2.3">
                <p id="section-toc.1-1.8.2.3.1"><a href="#section-8.3" class="xref">8.3</a>.  <a href="#name-new-additional-information-" class="xref">New Additional Information PvD Keys Registry</a><a href="#section-toc.1-1.8.2.3.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.8.2.4">
                <p id="section-toc.1-1.8.2.4.1"><a href="#section-8.4" class="xref">8.4</a>.  <a href="#name-new-pvd-option-flags-regist" class="xref">New PvD Option Flags Registry</a><a href="#section-toc.1-1.8.2.4.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.8.2.5">
                <p id="section-toc.1-1.8.2.5.1"><a href="#section-8.5" class="xref">8.5</a>.  <a href="#name-pvd-json-media-type-registr" class="xref">PvD JSON Media Type Registration</a><a href="#section-toc.1-1.8.2.5.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty 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-references" class="xref">References</a><a href="#section-toc.1-1.9.1" class="pilcrow">¶</a></p>
<ul class="toc ulEmpty compact">
<li class="toc ulEmpty compact" id="section-toc.1-1.9.2.1">
                <p id="section-toc.1-1.9.2.1.1"><a href="#section-9.1" class="xref">9.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a><a href="#section-toc.1-1.9.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc ulEmpty compact" id="section-toc.1-1.9.2.2">
                <p id="section-toc.1-1.9.2.2.1"><a href="#section-9.2" class="xref">9.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a><a href="#section-toc.1-1.9.2.2.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="toc ulEmpty compact" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-appendix.a" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a><a href="#section-toc.1-1.10.1" class="pilcrow">¶</a></p>
</li>
          <li class="toc ulEmpty compact" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#section-appendix.b" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a><a href="#section-toc.1-1.11.1" class="pilcrow">¶</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">Provisioning Domains (PvDs) are defined in <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span> as consistent
sets of network configuration information. This information includes
properties that are traditionally associated with a single networking
interface, such as source addresses, DNS configuration, proxy configuration,
and gateway addresses.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">Clients that are aware of PvDs can take advantage of multiple network
interfaces simultaneously. This enables using two PvDs in parallel for
separate connections or for multi-path transports.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">While most PvDs today are discovered implicitly (such as by receiving
information via Router Advertisements from a router on a network
that a client host directly connects to), <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span> also defines the notion
of Explicit PvDs. IPsec Virtual Private Networks are considered Explicit PvDs,
but Explicit PvDs can also be discovered via the local network router.
Discovering Explicit PvDs allows two key advancements in managing multiple
      PvDs:<a href="#section-1-3" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-1-4">
        <li id="section-1-4.1">The ability to discover and use multiple PvDs on a single
 interface,
such as when a local router can provide connectivity to two different
Internet Service Providers.<a href="#section-1-4.1" class="pilcrow">¶</a>
</li>
        <li id="section-1-4.2">The ability to associate Additional Information about PvDs to
 describe
the properties of the network.<a href="#section-1-4.2" class="pilcrow">¶</a>
</li>
      </ol>
<p id="section-1-5">While <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span> defines the concept
      of Explicit PvDs, it does not define
the mechanism for discovering multiple Explicit PvDs on a single network
and their Additional Information.<a href="#section-1-5" class="pilcrow">¶</a></p>
<p id="section-1-6">This document specifies a way to identify PvDs with Fully Qualified
Domain Names (FQDNs), called PvD IDs. Those identifiers are advertised in
a new Router Advertisement (RA) <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span>
option called
the PvD Option, which, when present, associates
the PvD ID with all the information present in the Router Advertisement
as well as any configuration object, such as addresses, derived from
it. The PvD Option may also contain a set of
other RA options, along with an optional inner Router Advertisement
message header. These options and optional inner header are only visible
to 'PvD-aware' hosts, allowing such hosts to have a specialized view of the
network configuration.<a href="#section-1-6" class="pilcrow">¶</a></p>
<p id="section-1-7">Since PvD IDs are used to identify different ways to access the
Internet, multiple PvDs (with different PvD IDs) can be provisioned on
a single host interface. Similarly, the same PvD ID could be used on
different interfaces of a host in order to inform that those PvDs
ultimately provide equivalent services.<a href="#section-1-7" class="pilcrow">¶</a></p>
<p id="section-1-8">This document also introduces a mechanism for hosts to retrieve
      optional Additional Information related to a specific PvD by means of an
      HTTP-over-TLS query using a URI derived from the PvD ID. The retrieved
      JSON object contains Additional Information that would typically be
      considered too large to be directly included in the Router
      Advertisement but might be considered useful to the applications, or
      even sometimes users, when choosing which PvD should be used.<a href="#section-1-8" class="pilcrow">¶</a></p>
<p id="section-1-9">For example, if Alice has both a cellular network provider and a
broadband provider in her home, her PvD-aware devices and applications
would be aware of both available uplinks. These applications
could fail-over between these networks or run connections over both
(potentially using multi-path transports). Applications could also select
specific uplinks based on the properties of the network; for example,
if the cellular network provides free high-quality video streaming,
a video-streaming application could select that network while most of the
other traffic on Alice's device uses the broadband provider.<a href="#section-1-9" class="pilcrow">¶</a></p>
<div id="specification-of-requirements">
<section id="section-1.1">
        <h3 id="name-specification-of-requiremen">
<a href="#section-1.1" class="section-number selfRef">1.1. </a><a href="#name-specification-of-requiremen" class="section-name selfRef">Specification of Requirements</a>
        </h3>
<p id="section-1.1-1">
    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-1.1-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="terminology">
<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">This document uses the following terminology:<a href="#section-2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-2-2">
        <dt id="section-2-2.1">Provisioning Domain (PvD):</dt>
        <dd id="section-2-2.2">
  A set of network configuration information; for more information, see <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-2-2.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.3">PvD ID:</dt>
        <dd id="section-2-2.4">
  A Fully Qualified Domain Name (FQDN) used to identify a PvD.<a href="#section-2-2.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.5">Explicit PvD:</dt>
        <dd id="section-2-2.6">
  A PvD uniquely identified with a PvD ID. For more information, see <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-2-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.7">Implicit PvD:</dt>
        <dd id="section-2-2.8">
  A PvD that, in the absence of a PvD ID,
is identified by the host interface to which it is attached and the
address of the advertising router. See also <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-2-2.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.9">PvD-aware host:</dt>
        <dd id="section-2-2.10">
  A host that supports the association of
network configuration information into PvDs and the use of these
PvDs as described in this document. Also named "PvD-aware node" in <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-2-2.10" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
</section>
</div>
<div id="ra">
<section id="section-3">
      <h2 id="name-provisioning-domain-identif">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-provisioning-domain-identif" class="section-name selfRef">Provisioning Domain Identification Using Router
      Advertisements</a>
      </h2>
<p id="section-3-1">Explicit PvDs are identified by a PvD ID. The PvD ID is a Fully
Qualified Domain Name (FQDN) that identifies the network operator.
Network operators <span class="bcp14">MUST</span> use names that they own or manage to
avoid naming conflicts. The same PvD ID <span class="bcp14">MAY</span> be used in
several access networks when they ultimately provide identical services
(e.g., in all home networks subscribed to the same service); else, the
PvD ID <span class="bcp14">MUST</span> be different to follow <span><a href="https://www.rfc-editor.org/rfc/rfc7556#section-2.4" class="relref">Section 2.4</a> of [<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-3-1" class="pilcrow">¶</a></p>
<div id="pvd-id-option-for-router-advertisements">
<section id="section-3.1">
        <h3 id="name-pvd-option-for-router-adver">
<a href="#section-3.1" class="section-number selfRef">3.1. </a><a href="#name-pvd-option-for-router-adver" class="section-name selfRef">PvD Option for Router Advertisements</a>
        </h3>
<p id="section-3.1-1">This document introduces a Router Advertisement (RA) option called
the PvD Option. It is used to convey the FQDN identifying a given PvD (see
<a href="#format" class="xref">Figure 1</a>), bind the PvD ID with configuration
information received over DHCPv4 (see <a href="#dhcpv4" class="xref">Section 3.4.2</a>), enable
the use of HTTP over TLS to retrieve the PvD Additional Information
JSON object (see <a href="#data" class="xref">Section 4</a>), as well as contain
any other
RA options that would otherwise be valid in the RA.<a href="#section-3.1-1" class="pilcrow">¶</a></p>
<span id="name-pvd-option-format"></span><div id="format">
<figure id="figure-1">
          <div class="artwork art-text alignLeft" id="section-3.1-2.1">
<pre>
 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Type      |    Length     |H|L|R|     Reserved    | Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Sequence Number         |                             ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                             ...
...                         PvD ID FQDN                       ...
...             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...             |                  Padding                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                             ...
...            Router Advertisement message header            ...
...             (Only present when R-flag is set)             ...
...                                                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-pvd-option-format" class="selfRef">PvD Option Format</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-3.1-3">
          <dt id="section-3.1-3.1">Type:</dt>
          <dd id="section-3.1-3.2">
  (8 bits) Set to 21.<a href="#section-3.1-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.3">Length:</dt>
          <dd id="section-3.1-3.4">
  (8 bits) The length of the option in
units of 8 octets, including the Type and Length fields, the
Router Advertisement message header, if any, as well as the RA
options that are included within the PvD Option.<a href="#section-3.1-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.5">H-flag:</dt>
          <dd id="section-3.1-3.6">
  (1 bit) 'HTTP' flag stating whether some PvD Additional Information is made
  available through HTTP over TLS, as described in <a href="#data" class="xref">Section 4</a>.<a href="#section-3.1-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.7">L-flag:</dt>
          <dd id="section-3.1-3.8">
  (1 bit) 'Legacy' flag stating whether the PvD is associated with
IPv4 information assigned using DHCPv4 (see <a href="#dhcpv4" class="xref">Section 3.4.2</a>).<a href="#section-3.1-3.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.9">R-flag:</dt>
          <dd id="section-3.1-3.10">
  (1 bit) 'Router Advertisement' flag stating whether the PvD Option header is
  followed (right after padding to the next 64-bit boundary) by a Router
  Advertisement message header (see <span><a href="https://www.rfc-editor.org/rfc/rfc4861#section-4.2" class="relref">Section 4.2</a> of [<a href="#RFC4861" class="xref">RFC4861</a>]</span>). The usage of the inner message header
  is described in
  <a href="#host" class="xref">Section 3.4</a>.<a href="#section-3.1-3.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.11">Reserved:</dt>
          <dd id="section-3.1-3.12">
  (9 bits) Reserved for later use. It
<span class="bcp14">MUST</span> be set to zero by the sender and ignored by the
   receiver.<a href="#section-3.1-3.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.13">Delay:</dt>
          <dd id="section-3.1-3.14">
  (4 bits) Unsigned integer used to delay HTTP GET queries from hosts by a
  randomized backoff (see <a href="#retr" class="xref">Section 4.1</a>). If the
  H-flag is not set, senders <span class="bcp14">SHOULD</span> set the delay to zero, and
  receivers <span class="bcp14">SHOULD</span> ignore the value.<a href="#section-3.1-3.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.15">Sequence Number:</dt>
          <dd id="section-3.1-3.16">
  (16 bits) Sequence number for the PvD Additional Information, as described
  in
  <a href="#data" class="xref">Section 4</a>. If the H-flag is not set, senders
  <span class="bcp14">SHOULD</span> set the Sequence Number to zero, and receivers
  <span class="bcp14">SHOULD</span> ignore the value.<a href="#section-3.1-3.16" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.17">PvD ID FQDN:</dt>
          <dd id="section-3.1-3.18">
  The FQDN used as PvD ID encoded in DNS format, as described in <span><a href="https://www.rfc-editor.org/rfc/rfc1035#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC1035" class="xref">RFC1035</a>]</span>. Domain name compression
  as described in <span><a href="https://www.rfc-editor.org/rfc/rfc1035#section-4.1.4" class="relref">Section 4.1.4</a> of [<a href="#RFC1035" class="xref">RFC1035</a>]</span>
            <span class="bcp14">MUST NOT</span> be used.<a href="#section-3.1-3.18" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.19">Padding:</dt>
          <dd id="section-3.1-3.20">
  Zero or more padding octets to the next 8-octet boundary (see <span><a href="https://www.rfc-editor.org/rfc/rfc4861#section-4.6" class="relref">Section 4.6</a> of [<a href="#RFC4861" class="xref">RFC4861</a>]</span>). It <span class="bcp14">MUST</span>
  be set to zero by the sender and ignored by the receiver.<a href="#section-3.1-3.20" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.21">RA message header:</dt>
          <dd id="section-3.1-3.22">
  (16 octets) When the R-flag is set, a full Router Advertisement message
  header as specified in <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span>. The sender
  <span class="bcp14">MUST</span> set the Type field to 134 (the value for "Router
  Advertisement") and set the Code field to 0.  Receivers <span class="bcp14">MUST</span>
  ignore both of these fields. The Checksum field <span class="bcp14">MUST</span> be set
  to 0
  by the sender; non-zero checksums <span class="bcp14">MUST</span> be ignored by the
  receiver without causing the processing of the message to fail.  All other
  fields are to be set and parsed as specified in <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span> or any updating documents.<a href="#section-3.1-3.22" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.1-3.23">Options:</dt>
          <dd id="section-3.1-3.24">
  Zero or more RA options that would otherwise be valid as part of the Router
  Advertisement main body but are instead included in the PvD Option so as to
  be ignored by hosts that are not PvD aware.<a href="#section-3.1-3.24" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-3.1-4"><a href="#pvd_example" class="xref">Figure 2</a> shows an example of a
        PvD Option with "example.org" as the PvD ID FQDN and includes both a
        Recursive DNS Server (RDNSS) option and a Prefix Information
        Option. It has a Sequence Number of 123 and indicates the presence of
        PvD Additional Information that is expected to be fetched with a delay
        factor of 1.<a href="#section-3.1-4" class="pilcrow">¶</a></p>
<span id="name-example-pvd-option"></span><div id="pvd_example">
<figure id="figure-2">
          <div class="artwork art-text alignLeft" id="section-3.1-5.1">
<pre>
 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+-----------------------------------------------+
| Type: 21      |  Length: 12   |1|0|0|     Reserved    |Delay:1|
+---------------+-------------------------------+---------------+
|       Seq number: 123         |      7        |       e       |
+---------------+-----------------------------------------------+
|      x        |       a       |      m        |       p       |
+---------------------------------------------------------------+
|      l        |       e       |      3        |       o       |
+---------------------------------------------------------------+
|      r        |       g       |      0        |   0 (padding) |
+---------------------------------------------------------------+
|   0 (padding) |  0 (padding)  |   0 (padding) |   0 (padding) |
+---------------+---------------+---------------+---------------+
|  RDNSS option (RFC 8106) length: 5                          ...
...                                                           ...
...                                                             |
+---------------------------------------------------------------+
| Prefix Information Option (RFC 4861) length: 4              ...
...                                                             |
...                                                             |
+---------------------------------------------------------------+
</pre>
</div>
<figcaption><a href="#figure-2" class="selfRef">Figure 2</a>:
<a href="#name-example-pvd-option" class="selfRef">Example PvD Option</a>
          </figcaption></figure>
</div>
</section>
</div>
<div id="router">
<section id="section-3.2">
        <h3 id="name-router-behavior">
<a href="#section-3.2" class="section-number selfRef">3.2. </a><a href="#name-router-behavior" class="section-name selfRef">Router Behavior</a>
        </h3>
<p id="section-3.2-1">A router <span class="bcp14">MAY</span> send RAs containing one PvD Option but
        <span class="bcp14">MUST NOT</span> include more than one PvD Option in each
        RA. The PvD Option <span class="bcp14">MUST NOT</span> contain further PvD
        Options.<a href="#section-3.2-1" class="pilcrow">¶</a></p>
<p id="section-3.2-2">The PvD Option <span class="bcp14">MAY</span> contain zero, one, or more RA
        options that would otherwise be valid as part of the same RA. Such
        options are processed by PvD-aware hosts and ignored by other hosts as
        per <span><a href="https://www.rfc-editor.org/rfc/rfc4861#section-4.2" class="relref">Section 4.2</a> of [<a href="#RFC4861" class="xref">RFC4861</a>]</span>.<a href="#section-3.2-2" class="pilcrow">¶</a></p>
<p id="section-3.2-3">In order to provide multiple different PvDs, a router
        <span class="bcp14">MUST</span> send multiple RAs. RAs sent from different
        link-local source addresses establish distinct Implicit PvDs in the
        absence of a PvD Option. Explicit PvDs <span class="bcp14">MAY</span> share
        link-local source addresses with an Implicit PvD and any number of
        other Explicit PvDs.<a href="#section-3.2-3" class="pilcrow">¶</a></p>
<p id="section-3.2-4">In other words, different Explicit PvDs <span class="bcp14">MAY</span> be
        advertised with RAs using the same link-local source address, but
        different Implicit PvDs, advertised by different RAs,
        <span class="bcp14">MUST</span> use different link-local addresses because these
        Implicit PvDs are identified by the source addresses of the RAs. If a
        link-local address on the router is changed, then any new RA will be
        interpreted as a different Implicit PvD by PvD-aware hosts.<a href="#section-3.2-4" class="pilcrow">¶</a></p>
<p id="section-3.2-5">As specified in <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span> and <span>[<a href="#RFC6980" class="xref">RFC6980</a>]</span>, when the set of options causes
        the size of an advertisement to exceed the link MTU, multiple router
        advertisements <span class="bcp14">MUST</span> be sent to avoid fragmentation,
        each containing a subset of the options. In such cases, the PvD Option
        header (i.e., all fields except the Options field)
        <span class="bcp14">MUST</span> be repeated in all the transmitted RAs. 
The options within the Options field <span class="bcp14">MAY</span> be transmitted only
once, included in one of the transmitted PvD Options.<a href="#section-3.2-5" class="pilcrow">¶</a></p>
</section>
</div>
<div id="non-pvd-aware-host-behavior">
<section id="section-3.3">
        <h3 id="name-non-pvd-aware-host-behavior">
<a href="#section-3.3" class="section-number selfRef">3.3. </a><a href="#name-non-pvd-aware-host-behavior" class="section-name selfRef">Non-PvD-Aware Host Behavior</a>
        </h3>
<p id="section-3.3-1">As the PvD Option has a new option code, non-PvD-aware hosts will
        simply ignore the PvD Option and all the options it contains (see
        <span><a href="https://www.rfc-editor.org/rfc/rfc4861#section-4.2" class="relref">Section 4.2</a> of [<a href="#RFC4861" class="xref">RFC4861</a>]</span>). This
        ensures the backward compatibility required in <span><a href="https://www.rfc-editor.org/rfc/rfc7556#section-3.3" class="relref">Section 3.3</a> of [<a href="#RFC7556" class="xref">RFC7556</a>]</span>.  This behavior allows for a
        mixed-mode network where a mix of PvD-aware and non-PvD-aware hosts
        coexist.<a href="#section-3.3-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="host">
<section id="section-3.4">
        <h3 id="name-pvd-aware-host-behavior">
<a href="#section-3.4" class="section-number selfRef">3.4. </a><a href="#name-pvd-aware-host-behavior" class="section-name selfRef">PvD-Aware Host Behavior</a>
        </h3>
<p id="section-3.4-1">Hosts <span class="bcp14">MUST</span> associate received RAs and included
        configuration information (e.g., Router Valid Lifetime, Prefix
        Information <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span>, Recursive DNS
        Server <span>[<a href="#RFC8106" class="xref">RFC8106</a>]</span>, and Routing
 Information
        <span>[<a href="#RFC4191" class="xref">RFC4191</a>]</span> options) with the Explicit
        PvD identified by the first PvD Option present in the received RA, if
        any, or with the Implicit PvD identified by the host interface and the
        source address of the received RA otherwise.  If an RA message header
        is present both within the PvD Option and outside it, the header
        within the PvD Option takes precedence.<a href="#section-3.4-1" class="pilcrow">¶</a></p>
<p id="section-3.4-2">In case multiple PvD Options are found in a given RA, hosts
        <span class="bcp14">MUST</span> ignore all but the first PvD Option.<a href="#section-3.4-2" class="pilcrow">¶</a></p>
<p id="section-3.4-3">If a host receives PvD Options flags that it does not recognize
        (currently in the Reserved field), it <span class="bcp14">MUST</span> ignore these
        flags.<a href="#section-3.4-3" class="pilcrow">¶</a></p>
<p id="section-3.4-4">Similarly, hosts <span class="bcp14">MUST</span> associate all network
        configuration objects (e.g., default routers, addresses, more specific
        routes, and DNS Recursive Resolvers) with the PvD associated with the
        RA that provisioned the object. For example, addresses that are
        generated using a received Prefix Information Option (PIO) are
        associated with the PvD of the last received RA that included the
        given PIO.<a href="#section-3.4-4" class="pilcrow">¶</a></p>
<p id="section-3.4-5">PvD IDs <span class="bcp14">MUST</span> be compared in a case-insensitive
 manner as defined by
<span>[<a href="#RFC4343" class="xref">RFC4343</a>]</span>. For example, "pvd.example.com." or
"PvD.Example.coM."
would refer to the same PvD.<a href="#section-3.4-5" class="pilcrow">¶</a></p>
<p id="section-3.4-6">While performing PvD-specific operations such as resolving names,
        executing the default address selection algorithm <span>[<a href="#RFC6724" class="xref">RFC6724</a>]</span>, or executing the default router
        selection algorithm when forwarding packets <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span> <span>[<a href="#RFC4191" class="xref">RFC4191</a>]</span>
          <span>[<a href="#RFC8028" class="xref">RFC8028</a>]</span>, hosts and applications
        <span class="bcp14">MAY</span> consider only the configuration associated with any
        non-empty subset of PvDs. For example, a host <span class="bcp14">MAY</span>
        associate a given process with a specific PvD, or a specific set of
        PvDs, while associating another process with another PvD. A PvD-aware
        application might also be able to select, on a per-connection basis,
        which PvDs should be used. In particular, constrained devices such as
        small battery-operated devices (e.g., Internet of Things (IoT)) or
 devices with limited
        CPU or memory resources may purposefully use a single PvD while
        ignoring some received RAs containing different PvD IDs.<a href="#section-3.4-6" class="pilcrow">¶</a></p>
<p id="section-3.4-7">The way an application expresses its desire to use a given PvD, or
        a set of PvDs, and the way this selection is enforced are out of the
        scope of this document. Useful insights about these considerations can
        be found in <span>[<a href="#I-D.kline-mif-mpvd-api-reqs" class="xref">MPVD-API</a>]</span>.<a href="#section-3.4-7" class="pilcrow">¶</a></p>
<div id="dhcpv6">
<section id="section-3.4.1">
          <h4 id="name-dhcpv6-configuration-associ">
<a href="#section-3.4.1" class="section-number selfRef">3.4.1. </a><a href="#name-dhcpv6-configuration-associ" class="section-name selfRef">DHCPv6 Configuration Association</a>
          </h4>
<p id="section-3.4.1-1">When a host retrieves stateless configuration elements using
          DHCPv6 (e.g., DNS recursive resolvers or DNS domain search lists
          <span>[<a href="#RFC3646" class="xref">RFC3646</a>]</span>), they <span class="bcp14">MUST</span>
          be associated with all the Explicit and Implicit PvDs received on
          the same interface and contained in an RA with the O-flag set <span>[<a href="#RFC4861" class="xref">RFC4861</a>]</span>.<a href="#section-3.4.1-1" class="pilcrow">¶</a></p>
<p id="section-3.4.1-2">When a host retrieves stateful assignments using DHCPv6, such
assignments <span class="bcp14">MUST</span> be associated with the received PvD that was
received with RAs with the M-flag set and including a matching PIO.
A PIO is considered to match a DHCPv6 assignment when the IPv6 prefix
from the PIO includes the assignment from DHCPv6. For example,
if a PvD's associated PIO defines the prefix <code>2001:db8:cafe::/64</code>,
a DHCPv6 IA_NA message that assigns the address
<code>2001:db8:cafe::1234:4567</code>
would be considered to match.<a href="#section-3.4.1-2" class="pilcrow">¶</a></p>
<p id="section-3.4.1-3">In cases where an address would be assigned by DHCPv6 and no
   matching
PvD could be found, hosts <span class="bcp14">MAY</span> associate the assigned address
with any
Implicit PvD received on the same interface or to multiple Implicit PvDs
received on the same interface. This is intended to resolve
backward-compatibility
issues with rare deployments choosing to assign addresses with DHCPv6 while
not sending any matching PIO. Implementations are suggested to flag or log
such scenarios as errors to help detect misconfigurations.<a href="#section-3.4.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="dhcpv4">
<section id="section-3.4.2">
          <h4 id="name-dhcpv4-configuration-associ">
<a href="#section-3.4.2" class="section-number selfRef">3.4.2. </a><a href="#name-dhcpv4-configuration-associ" class="section-name selfRef">DHCPv4 Configuration Association</a>
          </h4>
<p id="section-3.4.2-1">Associating DHCPv4 <span>[<a href="#RFC2131" class="xref">RFC2131</a>]</span>
          configuration elements with Explicit PvDs allows hosts to treat a
          set of IPv4 and IPv6 configurations as a single PvD with shared
          properties. For example, consider a router that provides two
          different uplinks. One could be a broadband network that has data
          rate and streaming properties described in PvD Additional
          Information and that provides both IPv4 and IPv6 network access. The
          other could be a cellular network that provides only IPv6 network
          access and uses NAT64 <span>[<a href="#RFC6146" class="xref">RFC6146</a>]</span>. The
          broadband network can be represented by an Explicit PvD that points
          to the Additional Information and also marks association with DHCPv4
          information. The cellular network can be represented by a different
          Explicit PvD that is not associated with DHCPv4.<a href="#section-3.4.2-1" class="pilcrow">¶</a></p>
<p id="section-3.4.2-2">When a PvD-aware host retrieves configuration elements from
          DHCPv4, the information is associated either with a single Explicit
          PvD on that interface or else with all Implicit PvDs on the same
          interface.<a href="#section-3.4.2-2" class="pilcrow">¶</a></p>
<p id="section-3.4.2-3">An Explicit PvD indicates its association with DHCPv4 information
          by setting the L-flag in the PvD Option. If there is exactly one
          Explicit PvD that sets this flag, hosts <span class="bcp14">MUST</span>
          associate the DHCPv4 information with that PvD. Multiple Explicit
          PvDs on the same interface marking this flag is a misconfiguration,
          and hosts <span class="bcp14">SHOULD NOT</span> associate the DHCPv4 information
          with any Explicit PvD in this case.<a href="#section-3.4.2-3" class="pilcrow">¶</a></p>
<p id="section-3.4.2-4">If no single Explicit PvD claims association with DHCPv4, the
          configuration elements coming from DHCPv4 <span class="bcp14">MUST</span> be
          associated with all Implicit PvDs identified by the interface on
          which the DHCPv4 transaction happened. This maintains existing host
          behavior.<a href="#section-3.4.2-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="connection-sharing-by-the-host">
<section id="section-3.4.3">
          <h4 id="name-connection-sharing-by-the-h">
<a href="#section-3.4.3" class="section-number selfRef">3.4.3. </a><a href="#name-connection-sharing-by-the-h" class="section-name selfRef">Connection Sharing by the Host</a>
          </h4>
<p id="section-3.4.3-1">The situation in which a host shares connectivity from an
          upstream interface (e.g., cellular) to a downstream interface (e.g.,
          Wi-Fi) is known as 'tethering'. Techniques such as ND Proxy <span>[<a href="#RFC4389" class="xref">RFC4389</a>]</span>, 64share <span>[<a href="#RFC7278" class="xref">RFC7278</a>]</span>, or prefix delegation (e.g., using DHCPv6-PD
          <span>[<a href="#RFC8415" class="xref">RFC8415</a>]</span>) may be used for that
          purpose.<a href="#section-3.4.3-1" class="pilcrow">¶</a></p>
<p id="section-3.4.3-2">Whenever the RAs received from the upstream interface contain a
          PvD Option, hosts that are sharing connectivity
          <span class="bcp14">SHOULD</span> include a PvD Option within the RAs sent
          downstream with:<a href="#section-3.4.3-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3.4.3-3.1">The same PvD ID FQDN<a href="#section-3.4.3-3.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-3.4.3-3.2">The same H-flag, Delay, and Sequence Number values<a href="#section-3.4.3-3.2" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-3.4.3-3.3">The L-flag set whenever the host is sharing IPv4 connectivity
received from the same upstream interface<a href="#section-3.4.3-3.3" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-3.4.3-3.4">The bits in the Reserved field set to 0<a href="#section-3.4.3-3.4" class="pilcrow">¶</a>
</li>
          </ul>
<p id="section-3.4.3-4">The values of the R-flag, Router Advertisement message
header, and Options field depend on whether or not the connectivity should
be shared only with PvD-aware hosts (see <a href="#router" class="xref">Section 3.2</a>). In particular,
all options received within the upstream PvD Option and included in
the downstream RA <span class="bcp14">SHOULD</span> be included in the downstream PvD
   Option.<a href="#section-3.4.3-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="usage-of-dns-servers">
<section id="section-3.4.4">
          <h4 id="name-usage-of-dns-servers">
<a href="#section-3.4.4" class="section-number selfRef">3.4.4. </a><a href="#name-usage-of-dns-servers" class="section-name selfRef">Usage of DNS Servers</a>
          </h4>
<p id="section-3.4.4-1">PvD-aware hosts can be provisioned with recursive DNS servers via
RA options passed within an Explicit PvD, via RA options associated
with an Implicit PvD, via DHCPv6 or DHCPv4, or from some other
provisioning mechanism that creates an Explicit PvD (such as a VPN).
In all of these cases, the recursive DNS server addresses
<span class="bcp14">SHOULD</span> be
associated with the corresponding PvD. Specifically, queries sent
to a configured recursive DNS server <span class="bcp14">SHOULD</span> be sent from a
local IP
address that was provisioned for the PvD via RA or DHCP. Answers
received from the DNS server <span class="bcp14">SHOULD</span> only be used on the same
   PvD.<a href="#section-3.4.4-1" class="pilcrow">¶</a></p>
<p id="section-3.4.4-2">PvD-aware applications will be able to select which PvD(s) to use
          for DNS resolution and connections, which allows them to effectively
          use multiple Explicit PvDs. In order to support non-PvD-aware
          applications, however, PvD-aware hosts <span class="bcp14">SHOULD</span> ensure
          that non-PvD-aware name resolution APIs like "getaddrinfo" only use
          resolvers from a single PvD for a given query.  Handling DNS across
          PvDs is discussed in <span><a href="https://www.rfc-editor.org/rfc/rfc7556#section-5.2.1" class="relref">Section 5.2.1</a> of [<a href="#RFC7556" class="xref">RFC7556</a>]</span>, and PvD APIs are discussed in <span><a href="https://www.rfc-editor.org/rfc/rfc7556#section-6" class="relref">Section 6</a> of [<a href="#RFC7556" class="xref">RFC7556</a>]</span>.<a href="#section-3.4.4-2" class="pilcrow">¶</a></p>
<p id="section-3.4.4-3">Maintaining the correct usage of DNS within PvDs avoids various
practical errors such as:<a href="#section-3.4.4-3" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3.4.4-4.1">A PvD associated with a VPN or otherwise private network may
provide DNS answers that contain addresses inaccessible over
another PvD. This includes the DNS queries to retrieve PvD
Additional Information, which could otherwise send identifying
information to the recursive DNS system (see <a href="#retr" class="xref">Section 4.1</a>).<a href="#section-3.4.4-4.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-3.4.4-4.2">A PvD that uses a NAT64 <span>[<a href="#RFC6146" class="xref">RFC6146</a>]</span> and DNS64
<span>[<a href="#RFC6147" class="xref">RFC6147</a>]</span> will synthesize IPv6 addresses in
DNS
answers that are not globally routable and would be invalid on
other PvDs. Conversely, an IPv4 address resolved via DNS on
another PvD cannot be directly used on a NAT64 network.<a href="#section-3.4.4-4.2" class="pilcrow">¶</a>
</li>
          </ul>
</section>
</div>
</section>
</div>
</section>
</div>
<div id="data">
<section id="section-4">
      <h2 id="name-provisioning-domain-additio">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-provisioning-domain-additio" class="section-name selfRef">Provisioning Domain Additional Information</a>
      </h2>
<p id="section-4-1">Additional information about the network characteristics can be
      retrieved based on the PvD ID. This set of information is called PvD
      Additional Information and is encoded as a JSON object <span>[<a href="#RFC8259" class="xref">RFC8259</a>]</span>.  This JSON object is restricted to
      the Internet JSON (I-JSON) profile, as defined in <span>[<a href="#RFC7493" class="xref">RFC7493</a>]</span>.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">The purpose of this JSON object is to provide Additional Information
      to applications on a client host about the connectivity that is provided
      using a given interface and source address. It typically includes data
      that would be considered too large, or not critical enough, to be
      provided within an RA option. The information contained in this object
      <span class="bcp14">MAY</span> be used by the operating system, network libraries,
      applications, or users in order to decide which set of PvDs should be
      used for which connection, as described in <a href="#host" class="xref">Section 3.4</a>.<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3">The Additional Information related to a PvD is specifically intended
      to be optional and is targeted at optimizing or informing the behavior
      of user-facing hosts. This information can be extended to provide hints
      for host system behavior (such as captive portal or walled-garden PvD
      detection) or application behavior (describing application-specific
      services offered on a given PvD). This content may not be appropriate
      for light-weight IoT devices. IoT devices might
      need only a subset of the information and would in some cases prefer a
      smaller representation like Concise Binary Object Representation (CBOR)
      <span>[<a href="#RFC7049" class="xref">RFC7049</a>]</span>. Delivering a reduced version
      of the PvD Additional Information designed for such devices is not
      defined in this document.<a href="#section-4-3" class="pilcrow">¶</a></p>
<div id="retr">
<section id="section-4.1">
        <h3 id="name-retrieving-the-pvd-addition">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-retrieving-the-pvd-addition" class="section-name selfRef">Retrieving the PvD Additional Information</a>
        </h3>
<p id="section-4.1-1">When the H-flag of the PvD Option is set, hosts <span class="bcp14">MAY</span>
        attempt to retrieve the PvD Additional Information associated with a
        given PvD by performing an HTTP-over-TLS <span>[<a href="#RFC2818" class="xref">RFC2818</a>]</span> GET query to
        <code>https://&lt;PvD-ID&gt;/.well-known/pvd</code>.  Inversely, hosts
        <span class="bcp14">MUST NOT</span> do so whenever the H-flag is not set.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">Recommendations for how to use TLS securely can be found in <span>[<a href="#RFC7525" class="xref">RFC7525</a>]</span>.<a href="#section-4.1-2" class="pilcrow">¶</a></p>
<p id="section-4.1-3">When a host retrieves the PvD Additional Information, it
 <span class="bcp14">MUST</span>
verify that the TLS server certificate is valid for the performed
request, specifically, that a DNS-ID <span>[<a href="#RFC6125" class="xref">RFC6125</a>]</span>
on the certificate is equal to
the PvD ID expressed as an FQDN. This validation indicates that the
owner of the FQDN authorizes its use with the prefix advertised by the router.
If this validation fails, hosts <span class="bcp14">MUST</span> close the connection and
treat the PvD
as if it has no Additional Information.<a href="#section-4.1-3" class="pilcrow">¶</a></p>
<p id="section-4.1-4">HTTP requests and responses for PvD Additional Information use the
"application/pvd+json" media type (see <a href="#pvd-json-media-type-registration" class="xref">Section 8.5</a>). Clients
<span class="bcp14">SHOULD</span> include this media type as an Accept header field in
their GET
requests, and servers <span class="bcp14">MUST</span> mark this media type as their
Content-Type
header field in responses.<a href="#section-4.1-4" class="pilcrow">¶</a></p>
<p id="section-4.1-5">Note that the DNS name resolution of the PvD ID, any connections
 made
for certificate validation (such as Online Certificate Status Protocol (OCSP)
<span>[<a href="#RFC6960" class="xref">RFC6960</a>]</span>), and
the HTTP request itself <span class="bcp14">MUST</span> be performed using the considered
PvD.
In other words, the name resolution, PKI checks, source address
selection, as well as the next-hop router selection <span class="bcp14">MUST</span> be
performed
while exclusively using the set of configuration information attached
with the PvD, as defined in <a href="#host" class="xref">Section 3.4</a>. In some
cases, it
may therefore be necessary to wait for an address to be available for
use (e.g., once the Duplicate Address Detection or DHCPv6 processes
are complete) before initiating the HTTP-over-TLS query. In order to
address privacy concerns around linkability of the PvD HTTP connection
with future user-initiated connections, if the host has a temporary address
per <span>[<a href="#RFC4941" class="xref">RFC4941</a>]</span> in this PvD, then it
<span class="bcp14">SHOULD</span> use a temporary address
to fetch the PvD Additional Information and <span class="bcp14">MAY</span> deprecate the
used
temporary address and generate a new temporary address afterward.<a href="#section-4.1-5" class="pilcrow">¶</a></p>
<p id="section-4.1-6">If the HTTP status of the answer is greater than or equal to 400,
        the host <span class="bcp14">MUST</span> close its connection and consider that
        there is no PvD Additional Information. If the HTTP status of the
        answer is between 300 and 399, inclusive, it <span class="bcp14">MUST</span>
        follow the redirection(s). If the HTTP status of the answer is between
        200 and 299, inclusive, the response is expected to be a single JSON
        object.<a href="#section-4.1-6" class="pilcrow">¶</a></p>
<p id="section-4.1-7">After retrieval of the PvD Additional Information, hosts
 <span class="bcp14">MUST</span> remember
the last Sequence Number value received in an RA including the same
PvD ID. Whenever a new RA for the same PvD is received with a different
Sequence Number value, or whenever the expiry date for the additional
information is reached, hosts <span class="bcp14">MUST</span> deprecate the Additional
Information
and stop using it.<a href="#section-4.1-7" class="pilcrow">¶</a></p>
<p id="section-4.1-8">Hosts retrieving a new PvD Additional Information object
 <span class="bcp14">MUST</span> check
for the presence and validity of the mandatory fields specified in
<a href="#aiformat" class="xref">Section 4.3</a>. A retrieved object including an
expiration
time that is already past or missing a mandatory element <span class="bcp14">MUST</span>
be
ignored.<a href="#section-4.1-8" class="pilcrow">¶</a></p>
<p id="section-4.1-9">In order to avoid synchronized queries toward the server hosting
the PvD Additional Information when an object expires, object updates
are delayed by a randomized backoff time.<a href="#section-4.1-9" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.1-10.1">When a host performs a JSON object update after it detected a
change in the PvD Option Sequence Number, it <span class="bcp14">MUST</span> add a delay
before sending the query. The target time for the delay is calculated
as a random time between zero and 2<sup>(10 + Delay)</sup> milliseconds,
where 'Delay' corresponds to the 4-bit unsigned integer in
the last received PvD Option.<a href="#section-4.1-10.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-4.1-10.2">When a host last retrieved a JSON object at time A that includes
   an
expiry time B using the "expires" key, and the host is configured to keep
the PvD Additional Information up to date, it <span class="bcp14">MUST</span> add some
randomness into
its calculation of the time to fetch the update. The target time for
fetching the updated object is calculated as a uniformly random time
in the interval [(B-A)/2,B].<a href="#section-4.1-10.2" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-4.1-11">In the example in <a href="#pvd_example" class="xref">Figure 2</a>,
 the
        Delay field value is 1; this means that the host calculates its delay
        by choosing a uniformly random time between 0 and 2<sup>(10 + 1)</sup>
        milliseconds, i.e., between 0 and 2048 milliseconds.<a href="#section-4.1-11" class="pilcrow">¶</a></p>
<p id="section-4.1-12">Since the Delay value is directly within the PvD Option rather
        than the object itself, an operator may perform a push-based update by
        incrementing the Sequence Number value while changing the Delay value
        depending on the criticality of the update and the capacity of its
        PvD Additional Information servers.<a href="#section-4.1-12" class="pilcrow">¶</a></p>
<p id="section-4.1-13">In addition to adding a random delay when fetching Additional
 Information, hosts
<span class="bcp14">MUST</span> enforce a minimum time between requesting Additional
Information
for a given PvD on the same network. This minimum time is
<span class="bcp14">RECOMMENDED</span>
to be 10 seconds, in order to avoid hosts causing a denial-of-service on the
PvD server. Hosts also <span class="bcp14">MUST</span> limit the number of requests that
are made to
different PvD Additional Information servers on the same network within a
short
period of time. A <span class="bcp14">RECOMMENDED</span> value is to issue no more than
five PvD
Additional Information requests in total on a given network within 10 seconds.
For more discussion, see <a href="#security" class="xref">Section 6</a>.<a href="#section-4.1-13" class="pilcrow">¶</a></p>
<p id="section-4.1-14">The PvD Additional Information object includes a set of IPv6
prefixes (under the key "prefixes") that <span class="bcp14">MUST</span> be checked
against all
the Prefix Information Options advertised in the RA. If any of the
prefixes included in any associated PIO is not covered by at least one of the
listed prefixes, the PvD Additional Information <span class="bcp14">MUST</span> be
considered
to be a misconfiguration and <span class="bcp14">MUST NOT</span> be used by the host. See
<a href="#misconfig" class="xref">Section 4.4</a> for more discussion on handling
such misconfigurations.<a href="#section-4.1-14" class="pilcrow">¶</a></p>
<p id="section-4.1-15">If the request for PvD Additional Information fails due to a TLS
 certificate validation
error, an HTTP error, or because the retrieved file does not contain valid PvD
JSON,
hosts <span class="bcp14">MUST</span> close any connection used to fetch the PvD
Additional Information
and <span class="bcp14">MUST NOT</span> request the information for that PvD ID again for
the duration
of the local network attachment. If a host detects 10 or more such failures
to fetch PvD Additional Information, the local network is assumed to be
misconfigured or under attack and the host <span class="bcp14">MUST NOT</span> make any
further
requests for any PvD Additional Information, belonging to any PvD ID, for
the duration of the local network attachment. For more discussion, see <a href="#security" class="xref">Section 6</a>.<a href="#section-4.1-15" class="pilcrow">¶</a></p>
</section>
</div>
<div id="serverop">
<section id="section-4.2">
        <h3 id="name-operational-consideration-t">
<a href="#section-4.2" class="section-number selfRef">4.2. </a><a href="#name-operational-consideration-t" class="section-name selfRef">Operational Consideration to Providing the PvD Additional
 Information</a>
        </h3>
<p id="section-4.2-1">Whenever the H-flag is set in the PvD Option, a valid PvD
        Additional Information object <span class="bcp14">MUST</span> be made available to
        all hosts receiving the RA by the network operator. In particular,
        when a captive portal is present, hosts <span class="bcp14">MUST</span> still be
        allowed to perform DNS, certificate validation, and HTTP-over-TLS
        operations related to the retrieval of the object, even before logging
        into the captive portal.<a href="#section-4.2-1" class="pilcrow">¶</a></p>
<p id="section-4.2-2">Routers <span class="bcp14">SHOULD</span> increment the PvD Option Sequence
        Number by one whenever a new PvD Additional Information object is
        available and should be retrieved by hosts. If the value exceeds what
        can be stored in the Sequence Number field, it <span class="bcp14">MUST</span>
        wrap back to zero.<a href="#section-4.2-2" class="pilcrow">¶</a></p>
<p id="section-4.2-3">The server providing the JSON files <span class="bcp14">SHOULD</span> also
        check whether the client address is contained by the prefixes listed
        in the Additional Information and <span class="bcp14">SHOULD</span> return a 403
        response code if there is no match.<a href="#section-4.2-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="aiformat">
<section id="section-4.3">
        <h3 id="name-pvd-additional-information-">
<a href="#section-4.3" class="section-number selfRef">4.3. </a><a href="#name-pvd-additional-information-" class="section-name selfRef">PvD Additional Information Format</a>
        </h3>
<p id="section-4.3-1">The PvD Additional Information is a JSON object.<a href="#section-4.3-1" class="pilcrow">¶</a></p>
<p id="section-4.3-2">The following table presents the mandatory keys, which
        <span class="bcp14">MUST</span> be included in the object:<a href="#section-4.3-2" class="pilcrow">¶</a></p>
<table class="center" id="table-1">
          <caption><a href="#table-1" class="selfRef">Table 1</a></caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">JSON key</th>
              <th class="text-left" rowspan="1" colspan="1">Description</th>
              <th class="text-left" rowspan="1" colspan="1">Type</th>
              <th class="text-left" rowspan="1" colspan="1">Example</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">identifier</td>
              <td class="text-left" rowspan="1" colspan="1">PvD ID FQDN</td>
              <td class="text-left" rowspan="1" colspan="1">String</td>
              <td class="text-left" rowspan="1" colspan="1">"pvd.example.com."</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">expires</td>
              <td class="text-left" rowspan="1" colspan="1">Date after which this object is no longer
       valid</td>
              <td class="text-left" rowspan="1" colspan="1">
                <span>[<a href="#RFC3339" class="xref">RFC3339</a>]</span> Date</td>
              <td class="text-left" rowspan="1" colspan="1">"2020-05-23T06:00:00Z"</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">prefixes</td>
              <td class="text-left" rowspan="1" colspan="1">Array of IPv6 prefixes valid for this PvD</td>
              <td class="text-left" rowspan="1" colspan="1">Array of strings</td>
              <td class="text-left" rowspan="1" colspan="1">["2001:db8:1::/48", "2001:db8:4::/48"]</td>
            </tr>
          </tbody>
        </table>
<p id="section-4.3-4">A retrieved object that does not include all three of these keys at
the root of the JSON object <span class="bcp14">MUST</span> be ignored. All three keys
need
to be validated; otherwise, the object <span class="bcp14">MUST</span> be ignored. The
value stored
for "identifier" <span class="bcp14">MUST</span> be matched against the PvD ID FQDN
presented in the
PvD Option using the comparison mechanism described in <a href="#host" class="xref">Section 3.4</a>.
The value stored for "expires" <span class="bcp14">MUST</span> be a valid date in the
future.
If the PIO of the received RA is not covered by at least one of the "prefixes"
key, the retrieved object <span class="bcp14">SHOULD</span> be ignored.<a href="#section-4.3-4" class="pilcrow">¶</a></p>
<p id="section-4.3-5">The following table presents some optional keys that
 <span class="bcp14">MAY</span> be
included in the object.<a href="#section-4.3-5" class="pilcrow">¶</a></p>
<table class="center" id="table-2">
          <caption><a href="#table-2" class="selfRef">Table 2</a></caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">JSON key</th>
              <th class="text-left" rowspan="1" colspan="1">Description</th>
              <th class="text-left" rowspan="1" colspan="1">Type</th>
              <th class="text-left" rowspan="1" colspan="1">Example</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">dnsZones</td>
              <td class="text-left" rowspan="1" colspan="1">DNS zones searchable and accessible</td>
              <td class="text-left" rowspan="1" colspan="1">Array of strings</td>
              <td class="text-left" rowspan="1" colspan="1">["example.com", "sub.example.com"]</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">noInternet</td>
              <td class="text-left" rowspan="1" colspan="1">No Internet; set to "true" when the PvD is
       restricted</td>
              <td class="text-left" rowspan="1" colspan="1">Boolean</td>
              <td class="text-left" rowspan="1" colspan="1">true</td>
            </tr>
          </tbody>
        </table>
<p id="section-4.3-7">It is worth noting that the JSON format allows for extensions.
Whenever an unknown key is encountered, it <span class="bcp14">MUST</span> be ignored
along with
its associated elements.<a href="#section-4.3-7" class="pilcrow">¶</a></p>
<p id="section-4.3-8">Private-use or experimental keys <span class="bcp14">MAY</span> be used in the
 JSON
dictionary. In order to avoid such keys colliding with the keys registered by
IANA,
implementers or vendors defining private-use or experimental
keys <span class="bcp14">MUST</span> create sub-dictionaries. If a set of PvD Additional
Information keys
are defined by an organization that has a formal URN namespace <span>[<a href="#IANA-URN" class="xref">IANA-URN</a>]</span>,
the URN namespace <span class="bcp14">SHOULD</span> be used as the top-level JSON key for
the sub-dictionary. For other private uses, the sub-dictionary key
<span class="bcp14">SHOULD</span> follow the format of "vendor-*", where the "*" is
replaced by the
implementer's or vendor's identifier. For example, keys specific to the FooBar
organization could use "vendor-foobar". If a host receives a sub-dictionary
with
an unknown key, the host <span class="bcp14">MUST</span> ignore the contents of the
 sub-dictionary.<a href="#section-4.3-8" class="pilcrow">¶</a></p>
<div id="example">
<section id="section-4.3.1">
          <h4 id="name-example">
<a href="#section-4.3.1" class="section-number selfRef">4.3.1. </a><a href="#name-example" class="section-name selfRef">Example</a>
          </h4>
<p id="section-4.3.1-1">The following two examples show how the JSON keys defined in this
document can be used:<a href="#section-4.3.1-1" class="pilcrow">¶</a></p>
<div id="section-4.3.1-2">
<pre class="sourcecode lang-json">
{
  "identifier": "cafe.example.com.",
  "expires": "2020-05-23T06:00:00Z",
  "prefixes": ["2001:db8:1::/48", "2001:db8:4::/48"],
}

{
  "identifier": "company.foo.example.com.",
  "expires": "2020-05-23T06:00:00Z",
  "prefixes": ["2001:db8:1::/48", "2001:db8:4::/48"],
  "vendor-foo":
    {
        "private-key": "private-value",
    },
}
</pre><a href="#section-4.3.1-2" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="misconfig">
<section id="section-4.4">
        <h3 id="name-detecting-misconfiguration-">
<a href="#section-4.4" class="section-number selfRef">4.4. </a><a href="#name-detecting-misconfiguration-" class="section-name selfRef">Detecting Misconfiguration and Misuse</a>
        </h3>
<p id="section-4.4-1">Hosts <span class="bcp14">MUST</span> validate the TLS server certificate when
 retrieving PvD
Additional Information, as detailed in <a href="#retr" class="xref">Section 4.1</a>.<a href="#section-4.4-1" class="pilcrow">¶</a></p>
<p id="section-4.4-2">Hosts <span class="bcp14">MUST</span> verify that all prefixes in all the RA
 PIOs are covered by a
prefix from the PvD Additional Information. An adversarial router
attempting to spoof the definition of an Explicit PvD, without the ability to
modify the PvD Additional Information, would need to perform IPv6-to-IPv6
Network
Prefix Translation (NPTv6) <span>[<a href="#RFC6296" class="xref">RFC6296</a>]</span> in order
to circumvent this check.
Thus, this check cannot prevent all spoofing, but it can detect
misconfiguration
or mismatched routers that are not adding a NAT.<a href="#section-4.4-2" class="pilcrow">¶</a></p>
<p id="section-4.4-3">If NPTv6 is being added in order to spoof PvD ownership, the HTTPS
        server for Additional Information can detect this misconfiguration.
        The HTTPS server <span class="bcp14">SHOULD</span> validate the source addresses
        of incoming connections (see <a href="#retr" class="xref">Section 4.1</a>). This check gives reasonable assurance that
 NPTv6 was not used and restricts the information to the valid network
 users.If the PvD does not
        provision IPv4 (it does not include the L-flag in the RA), the server
        cannot validate the source addresses of connections using IPv4. Thus,
        the PvD ID FQDN for such PvDs <span class="bcp14">SHOULD NOT</span> have a DNS A
        record.<a href="#section-4.4-3" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="operational-considerations">
<section id="section-5">
      <h2 id="name-operational-considerations">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-operational-considerations" class="section-name selfRef">Operational Considerations</a>
      </h2>
<p id="section-5-1">This section describes some example use cases of PvDs. For the sake
      of
simplicity, the RA messages will not be described in the usual ASCII art
but rather in an indented list. Values in the PvD Option header that are not
included in the example are assumed to be zero or false (such as the
H-flag, Sequence Number, and Delay fields).<a href="#section-5-1" class="pilcrow">¶</a></p>
<div id="exposing-extra-ra-options-to-pvd-aware-hosts">
<section id="section-5.1">
        <h3 id="name-exposing-extra-ra-options-t">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-exposing-extra-ra-options-t" class="section-name selfRef">Exposing Extra RA Options to PvD-Aware Hosts</a>
        </h3>
<p id="section-5.1-1">In this example, there is one RA message sent by the router. This
        message contains some options applicable to all hosts on the network
        and also a PvD Option that also contains other options only visible to
        PvD-aware hosts.<a href="#section-5.1-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.1-2.1">RA Header: router lifetime = 6000<a href="#section-5.1-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.1-2.2">Prefix Information Option: length = 4, prefix =
2001:db8:cafe::/64<a href="#section-5.1-2.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.1-2.3">
            <p id="section-5.1-2.3.1">PvD Option header: length = 3 + 5 + 4, PvD ID FQDN =
example.org., R-flag = 0 (actual length of the header with padding
24 bytes = 3 * 8 bytes)<a href="#section-5.1-2.3.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.1-2.3.2.1">Recursive DNS Server: length = 5, addresses =
       [2001:db8:cafe::53, 2001:db8:f00d::53]<a href="#section-5.1-2.3.2.1" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-5.1-2.3.2.2">Prefix Information Option: length = 4, prefix =
       2001:db8:f00d::/64<a href="#section-5.1-2.3.2.2" class="pilcrow">¶</a>
</li>
            </ul>
</li>
        </ul>
<p id="section-5.1-3">Note that a PvD-aware host will receive two different prefixes,
        <code>2001:db8:cafe::/64</code> and <code>2001:db8:f00d::/64</code>, both
 associated
        with the same PvD (identified by "example.org.").  A non-PvD-aware
        host will only receive one prefix, <code>2001:db8:cafe::/64</code>.<a href="#section-5.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="different-ras-for-pvd-aware-and-non-pvd-aware-hosts">
<section id="section-5.2">
        <h3 id="name-different-ras-for-pvd-aware">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-different-ras-for-pvd-aware" class="section-name selfRef">Different RAs for PvD-Aware and Non-PvD-Aware Hosts</a>
        </h3>
<p id="section-5.2-1">It is expected that for some years, networks will have a mixed
environment of PvD-aware hosts and non-PvD-aware hosts. If there is a
need to give specific information to PvD-aware hosts only, then it is
<span class="bcp14">RECOMMENDED</span> to send two RA messages, one for each class of
hosts.
This approach allows for two distinct sets of configuration information
to be sent in a way that will not disrupt non-PvD-aware hosts. It also
lowers the risk that a single RA message will approach its MTU limit due
to duplicated information.<a href="#section-5.2-1" class="pilcrow">¶</a></p>
<p id="section-5.2-2">If two RA messages are sent for this reason, they
 <span class="bcp14">MUST</span> be sent from two
different link-local source addresses (<a href="#router" class="xref">Section 3.2</a>). For example, here is the
RA sent for non-PvD-aware hosts:<a href="#section-5.2-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.2-3.1">RA Header: router lifetime = 6000 (non-PvD-aware hosts will use
          this router as a default router)<a href="#section-5.2-3.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.2-3.2">Prefix Information Option: length = 4, prefix =
   2001:db8:cafe::/64<a href="#section-5.2-3.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.2-3.3">Recursive DNS Server Option: length = 3, addresses =
   [2001:db8:cafe::53]<a href="#section-5.2-3.3" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.2-3.4">
            <p id="section-5.2-3.4.1">PvD Option header: length = 3 + 2, PvD ID FQDN =
     foo.example.org., R-flag = 1 (actual length of the header 24 bytes
     = 3 * 8 bytes)<a href="#section-5.2-3.4.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.2-3.4.2.1">RA Header: router lifetime = 0 (PvD-aware hosts will not use
              this router as a default router), implicit length = 2<a href="#section-5.2-3.4.2.1" class="pilcrow">¶</a>
</li>
            </ul>
</li>
        </ul>
<p id="section-5.2-4">And here is the RA sent for PvD-aware hosts:<a href="#section-5.2-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.2-5.1">RA Header: router lifetime = 0 (non-PvD-aware hosts will not use
          this router as a default router)<a href="#section-5.2-5.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.2-5.2">
            <p id="section-5.2-5.2.1">PvD Option header: length = 3 + 2 + 4 + 3, PvD ID FQDN =
            bar.example.org., R-flag = 1 (actual length of the header 24 bytes
            = 3 * 8 bytes)<a href="#section-5.2-5.2.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.2-5.2.2.1">RA Header: router lifetime = 1600 (PvD-aware hosts will use
              this router as a default router), implicit length = 2<a href="#section-5.2-5.2.2.1" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-5.2-5.2.2.2">Prefix Information Option: length = 4, prefix =
       2001:db8:f00d::/64<a href="#section-5.2-5.2.2.2" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-5.2-5.2.2.3">Recursive DNS Server Option: length = 3, addresses =
       [2001:db8:f00d::53]<a href="#section-5.2-5.2.2.3" class="pilcrow">¶</a>
</li>
            </ul>
</li>
        </ul>
<p id="section-5.2-6">In the above example, non-PvD-aware hosts will only use the first
        listed RA sent by their default router and use the
        <code>2001:db8:cafe::/64</code> prefix.  PvD-aware hosts will autonomously
        configure addresses from both PIOs but will only use the source
        address in <code>2001:db8:f00d::/64</code> to communicate past the
 first-hop router
        since only the router sending the second RA will be used as the
 default
        router; similarly, they will use the DNS server
 <code>2001:db8:f00d::53</code> when
        communicating from this address.<a href="#section-5.2-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="enabling-multi-homing-for-pvd-aware-hosts">
<section id="section-5.3">
        <h3 id="name-enabling-multihoming-for-pv">
<a href="#section-5.3" class="section-number selfRef">5.3. </a><a href="#name-enabling-multihoming-for-pv" class="section-name selfRef">Enabling Multihoming for PvD-Aware Hosts</a>
        </h3>
<p id="section-5.3-1">In this example, the goal is to have one prefix from one RA be
        usable by both non-PvD-aware and PvD-aware hosts and to have another
        prefix usable only by PvD-aware hosts. This allows PvD-aware hosts to
        be able to effectively multihome on the network.<a href="#section-5.3-1" class="pilcrow">¶</a></p>
<p id="section-5.3-2">The first RA is usable by all hosts. The only difference for
        PvD-aware hosts is that they can explicitly identify the PvD ID
        associated with the RA.  PvD-aware hosts will also use this prefix to
        communicate with non-PvD-aware hosts on the same network.<a href="#section-5.3-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.3-3.1">RA Header: router lifetime = 6000 (non-PvD-aware hosts will use
          this router as a default router)<a href="#section-5.3-3.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.3-3.2">Prefix Information Option: length = 4, prefix =
   2001:db8:cafe::/64<a href="#section-5.3-3.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.3-3.3">Recursive DNS Server Option: length = 3, addresses =
   [2001:db8:cafe::53]<a href="#section-5.3-3.3" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.3-3.4">PvD Option header: length = 3, PvD ID FQDN = foo.example.org.,
   R-flag = 0 (actual length of the header 24 bytes = 3 * 8 bytes)<a href="#section-5.3-3.4" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-5.3-4">The second RA contains a prefix usable only by PvD-aware
 hosts. Non-PvD-aware
hosts will ignore this RA; hence, only the PvD-aware hosts will be
 multihomed.<a href="#section-5.3-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.3-5.1">RA Header: router lifetime = 0 (non-PvD-aware hosts will not use
this router as a default router)<a href="#section-5.3-5.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.3-5.2">
            <p id="section-5.3-5.2.1">PvD Option header: length = 3 + 2 + 4 + 3, PvD ID FQDN =
     bar.example.org., R-flag = 1 (actual length of the header 24 bytes
     = 3 * 8 bytes)<a href="#section-5.3-5.2.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.3-5.2.2.1">RA Header: router lifetime = 1600 (PvD-aware hosts will use
              this router as a default router), implicit length = 2<a href="#section-5.3-5.2.2.1" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-5.3-5.2.2.2">Prefix Information Option: length = 4, prefix =
       2001:db8:f00d::/64<a href="#section-5.3-5.2.2.2" class="pilcrow">¶</a>
</li>
              <li class="normal" id="section-5.3-5.2.2.3">Recursive DNS Server Option: length = 3, addresses =
       [2001:db8:f00d::53]<a href="#section-5.3-5.2.2.3" class="pilcrow">¶</a>
</li>
            </ul>
</li>
        </ul>
<p id="section-5.3-6">Note: the above examples assume that the router has received its
 PvD IDs from upstream routers
or via some other configuration mechanism. Another document could define ways
for the router
to generate its own PvD IDs to allow the above scenario in the absence of PvD
ID provisioning.<a href="#section-5.3-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="providing-additional-information-to-pvd-aware-hosts">
<section id="section-5.4">
        <h3 id="name-providing-additional-inform">
<a href="#section-5.4" class="section-number selfRef">5.4. </a><a href="#name-providing-additional-inform" class="section-name selfRef">Providing Additional Information to PvD-Aware Hosts</a>
        </h3>
<p id="section-5.4-1">In this example, the router indicates that it provides Additional
 Information using the H-flag.
The Sequence Number on the PvD Option is set to 7 in this example.<a href="#section-5.4-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.4-2.1">RA Header: router lifetime = 6000<a href="#section-5.4-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.4-2.2">Prefix Information Option: length = 4, prefix =
   2001:db8:cafe::/64<a href="#section-5.4-2.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.4-2.3">Recursive DNS Server Option: length = 3, addresses =
   [2001:db8:cafe::53]<a href="#section-5.4-2.3" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.4-2.4">PvD Option header: length = 3, PvD ID FQDN = cafe.example.com.,
Sequence Number = 7, R-flag = 0, H-flag = 1 (actual length of the header with
padding
24 bytes = 3 * 8 bytes)<a href="#section-5.4-2.4" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-5.4-3">A PvD-aware host will fetch
        &lt;https://cafe.example.com/.well-known/pvd&gt; to get the additional
        information. The following example shows a GET request that the host
        sends, in HTTP/2 syntax <span>[<a href="#RFC7540" class="xref">RFC7540</a>]</span>:<a href="#section-5.4-3" class="pilcrow">¶</a></p>
<div id="section-5.4-4">
<pre class="sourcecode">
:method = GET
:scheme = https
:authority = cafe.example.com
:path = /.well-known/pvd
accept = application/pvd+json
</pre><a href="#section-5.4-4" class="pilcrow">¶</a>
</div>
<p id="section-5.4-5">The HTTP server will respond with the JSON Additional
 Information:<a href="#section-5.4-5" class="pilcrow">¶</a></p>
<div id="section-5.4-6">
<pre class="sourcecode lang-json">
:status = 200
content-type = application/pvd+json
content-length = 116

{
  "identifier": "cafe.example.com.",
  "expires": "2020-05-23T06:00:00Z",
  "prefixes": ["2001:db8:cafe::/48"],
}
</pre><a href="#section-5.4-6" class="pilcrow">¶</a>
</div>
<p id="section-5.4-7">At this point, the host has the PvD Additional Information and
 knows
        the expiry time.  When either the expiry time passes or a new
        Sequence Number is provided in an RA, the host will re-fetch the
        Additional Information.<a href="#section-5.4-7" class="pilcrow">¶</a></p>
<p id="section-5.4-8">For example, if the router sends a new RA with the Sequence Number
 set to 8,
the host will re-fetch the Additional Information:<a href="#section-5.4-8" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.4-9.1">PvD Option header: length = 3 + 5 + 4 , PvD ID FQDN =
   cafe.example.com.,
Sequence Number = 8, R-flag = 0, H-flag = 1 (actual length of the header with
padding
24 bytes = 3 * 8 bytes)<a href="#section-5.4-9.1" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-5.4-10">However, if the router sends a new RA, but the Sequence Number has
 not changed,
the host would not re-fetch the Additional Information (until and unless the
expiry time
of the Additional Information has passed).<a href="#section-5.4-10" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="security">
<section id="section-6">
      <h2 id="name-security-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-6-1">Since the PvD Option can contain an RA header and other RA options,
any security considerations that apply for specific RA options continue to
apply when used within a PvD Option.<a href="#section-6-1" class="pilcrow">¶</a></p>
<p id="section-6-2">Although some solutions such as IPsec or SEcure Neighbor Discovery
      (SeND) <span>[<a href="#RFC3971" class="xref">RFC3971</a>]</span> can be used in order to
      secure the IPv6 Neighbor Discovery Protocol, in practice, actual
      deployments largely rely on link-layer or physical-layer security
      mechanisms (e.g., 802.1x <span>[<a href="#IEEE8021X" class="xref">IEEE8021X</a>]</span>) in
      conjunction with RA-Guard <span>[<a href="#RFC6105" class="xref">RFC6105</a>]</span>.<a href="#section-6-2" class="pilcrow">¶</a></p>
<p id="section-6-3">If multiple RAs are sent for a single PvD to avoid fragmentation,
      dropping packets
can lead to processing only part of a PvD Option, which could lead to hosts
receiving only part of the contained options. As discussed in <a href="#router" class="xref">Section 3.2</a>, routers
<span class="bcp14">MUST</span> include the PvD Option in all fragments generated.<a href="#section-6-3" class="pilcrow">¶</a></p>
<p id="section-6-4">This specification does not improve the Neighbor Discovery Protocol
security model but simply validates that the owner of the PvD FQDN
authorizes its use with the prefix advertised by the router. In
combination with implicit trust in the local router (if present), this
gives the host some level of assurance that the PvD is authorized for
use in this environment. However, when the local router cannot be
trusted, no such guarantee is available.<a href="#section-6-4" class="pilcrow">¶</a></p>
<p id="section-6-5">It must be noted that <a href="#misconfig" class="xref">Section 4.4</a> of
      this document
only provides reasonable assurance against misconfiguration but does not
prevent a hostile network access provider from advertising incorrect
information that could lead applications or hosts to select a hostile PvD.
However, a host that correctly implements the multiple PvD architecture <span>[<a href="#RFC7556" class="xref">RFC7556</a>]</span>
using the mechanism described in this document will be less susceptible to
some attacks than a host that does not by being able to check for the various
misconfigurations or inconsistencies described in this document.<a href="#section-6-5" class="pilcrow">¶</a></p>
<p id="section-6-6">Since expiration times provided in PvD Additional Information use
      absolute time, these values can be skewed due to clock skew or for hosts
      without an accurate time base. Such time values <span class="bcp14">MUST NOT</span>
      be used for security-sensitive functionality or decisions.<a href="#section-6-6" class="pilcrow">¶</a></p>
<p id="section-6-7">An attacker generating RAs on a local network can use the H-flag and
      the PvD ID
to cause hosts on the network to make requests for PvD Additional Information
from servers. This can become a denial-of-service attack, in which an attacker
can amplify its attack by triggering TLS connections to arbitrary servers in
response
to sending UDP packets containing RA messages. To mitigate this attack, hosts
<span class="bcp14">MUST</span>:<a href="#section-6-7" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6-8.1">limit the rate at which they fetch a particular PvD's Additional
 Information;<a href="#section-6-8.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-6-8.2">limit the rate at which they fetch any PvD Additional Information
 on a given local
network;<a href="#section-6-8.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-6-8.3">stop making requests for a PvD ID that does not respond with valid
 JSON; and<a href="#section-6-8.3" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-6-8.4">stop making requests for all PvD IDs once a certain number of
 failures is reached
on a particular network.<a href="#section-6-8.4" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-6-9">Details are provided in <a href="#retr" class="xref">Section 4.1</a>. This
      attack can be targeted at generic web servers,
in which case the host behavior of stopping requesting for any server that
doesn't
behave like a PvD Additional Information server is critical. Limiting requests
for
a specific PvD ID might not be sufficient if the attacker changes the PvD ID
values
quickly, so hosts also need to stop requesting if they detect consistent
failure when
on a network that is under attack. For cases in which an attacker is pointing
hosts at
a valid PvD Additional Information server (but one that is not actually
associated
with the local network), the server <span class="bcp14">SHOULD</span> reject any requests
that do not originate
from the expected IPv6 prefix as described in <a href="#serverop" class="xref">Section 4.2</a>.<a href="#section-6-9" class="pilcrow">¶</a></p>
</section>
</div>
<div id="privacy-considerations">
<section id="section-7">
      <h2 id="name-privacy-considerations">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-privacy-considerations" class="section-name selfRef">Privacy Considerations</a>
      </h2>
<p id="section-7-1">Retrieval of the PvD Additional Information over HTTPS requires early
      communications between the connecting host and a server that may be
      located further than the first-hop router. Although this server is
      likely to be located within the same administrative domain as the
      default router, this property can't be ensured. To minimize the leakage
      of identity information while retrieving the PvD Additional Information,
      hosts <span class="bcp14">SHOULD</span> make use of an IPv6 temporary address and
      <span class="bcp14">SHOULD NOT</span> include any privacy-sensitive data, such as a
      User-Agent header field or an HTTP cookie.<a href="#section-7-1" class="pilcrow">¶</a></p>
<p id="section-7-2">Hosts might not always fetch PvD Additional Information, depending on
      whether or not they expect to use the information. However, if a host
      allows requesting Additional Information for certain PvD IDs,
      an attacker could send various PvD IDs in RAs to detect
      which PvD IDs are allowed by the client. To avoid this, hosts
      <span class="bcp14">SHOULD</span> either fetch Additional Information for all
      eligible PvD IDs on a given local network or fetch the information for
      none of them.<a href="#section-7-2" class="pilcrow">¶</a></p>
<p id="section-7-3">From a user privacy perspective, retrieving the PvD Additional
      Information
is not different from establishing a first connection to a remote
server or even performing a single DNS lookup. For example, most
operating systems already perform early queries to static web sites,
such as &lt;http://captive.example.com/hotspot-detect.html&gt;, in order to
detect the presence of a captive portal.<a href="#section-7-3" class="pilcrow">¶</a></p>
<p id="section-7-4">The DNS queries associated with the PvD Additional Information
      <span class="bcp14">MUST</span>
use the DNS servers indicated by the associated PvD, as described in
<a href="#retr" class="xref">Section 4.1</a>. This ensures the name of the PvD
Additional Information server
is not unintentionally sent on another network, thus leaking identifying
information about the networks with which the client is associated.<a href="#section-7-4" class="pilcrow">¶</a></p>
<p id="section-7-5">There may be some cases where hosts, for privacy reasons, should
refrain from accessing servers that are located outside a certain
network boundary. In practice, this could be implemented as an allowed list
of 'trusted' FQDNs and/or IP prefixes that the host is allowed to
communicate with. In such scenarios, the host <span class="bcp14">SHOULD</span> check that
the
provided PvD ID, as well as the IP address that it resolves into, are
part of the allowed list.<a href="#section-7-5" class="pilcrow">¶</a></p>
<p id="section-7-6">Network operators <span class="bcp14">SHOULD</span> restrict access to PvD
      Additional
Information to only expose it to hosts that are connected to the local
network, especially if the Additional Information would provide information
about local network configuration to attackers. This can be implemented by
allowing access from the addresses and prefixes that the router provides
for the PvD, which will match the prefixes contained in the PvD Additional
Information. This technique is described in <a href="#serverop" class="xref">Section 4.2</a>.<a href="#section-7-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="iana">
<section id="section-8">
      <h2 id="name-iana-considerations">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<div id="change-to-ipv6-neighbor-discovery-option-formats-registry">
<section id="section-8.1">
        <h3 id="name-change-to-ipv6-neighbor-dis">
<a href="#section-8.1" class="section-number selfRef">8.1. </a><a href="#name-change-to-ipv6-neighbor-dis" class="section-name selfRef">Change to IPv6 Neighbor Discovery Option Formats Registry</a>
        </h3>
<p id="section-8.1-1">IANA has removed the
'reclaimable' tag for value 21 for the PvD Option in the 
"IPv6 Neighbor Discovery Option Formats" registry.<a href="#section-8.1-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="new-entry-in-the-well-known-uris-registry">
<section id="section-8.2">
        <h3 id="name-new-entry-in-the-well-known">
<a href="#section-8.2" class="section-number selfRef">8.2. </a><a href="#name-new-entry-in-the-well-known" class="section-name selfRef">New Entry in the Well-Known URIs Registry</a>
        </h3>
<p id="section-8.2-1">IANA has added a new entry in the "Well-Known URIs" registry
        <span>[<a href="#RFC8615" class="xref">RFC8615</a>]</span> with the following
        information:<a href="#section-8.2-1" class="pilcrow">¶</a></p>
<p id="section-8.2-2">URI suffix: pvd<a href="#section-8.2-2" class="pilcrow">¶</a></p>
<p id="section-8.2-3">Change controller: IETF<a href="#section-8.2-3" class="pilcrow">¶</a></p>
<p id="section-8.2-4">Specification document: RFC 8801<a href="#section-8.2-4" class="pilcrow">¶</a></p>
<p id="section-8.2-5">Status: permanent<a href="#section-8.2-5" class="pilcrow">¶</a></p>
<p id="section-8.2-6">Related information: N/A<a href="#section-8.2-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="additional-information-pvd-keys-registry">
<section id="section-8.3">
        <h3 id="name-new-additional-information-">
<a href="#section-8.3" class="section-number selfRef">8.3. </a><a href="#name-new-additional-information-" class="section-name selfRef">New Additional Information PvD Keys Registry</a>
        </h3>
<p id="section-8.3-1">IANA has created and will maintain a new registry called
        "Additional Information PvD Keys", which reserves JSON keys for use in
        PvD Additional Information. The initial contents of this registry are
        given in <a href="#aiformat" class="xref">Section 4.3</a> (both
        the table of mandatory keys and the table of optional keys).<a href="#section-8.3-1" class="pilcrow">¶</a></p>
<p id="section-8.3-2">The status of a key as mandatory or optional is intentionally not
        denoted in the table to allow for flexibility in future use cases.
        Any new assignments of keys will be considered as optional for the
        purpose of the mechanism described in this document.<a href="#section-8.3-2" class="pilcrow">¶</a></p>
<p id="section-8.3-3">New assignments in the "Additional Information PvD Keys" registry
        will be administered by IANA through Expert Review <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.  Experts are requested to ensure
        that defined keys do not overlap in names or semantics and that they
 represent
        non-vendor-specific use cases. Vendor-specific keys
        <span class="bcp14">SHOULD</span> use sub-dictionaries, as described in <a href="#aiformat" class="xref">Section 4.3</a>.<a href="#section-8.3-3" class="pilcrow">¶</a></p>
<p id="section-8.3-4">IANA has placed the "Additional Information PvD Keys" registry
        within a new registry entitled "Provisioning Domains (PvDs)".<a href="#section-8.3-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="pvd-option-flags-registry">
<section id="section-8.4">
        <h3 id="name-new-pvd-option-flags-regist">
<a href="#section-8.4" class="section-number selfRef">8.4. </a><a href="#name-new-pvd-option-flags-regist" class="section-name selfRef">New PvD Option Flags Registry</a>
        </h3>
<p id="section-8.4-1">IANA has also created and will maintain a new registry entitled
        "PvD Option Flags". This new registry reserves bit positions from 0
        to 11 to be used in the PvD Option bitmask. This document assigns bit
        positions 0, 1, and 2 as shown in the table below. Future assignments
        require Standards Action <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-8.4-1" class="pilcrow">¶</a></p>
<div id="iana-flags">
<table class="center" id="table-3">
          <caption><a href="#table-3" class="selfRef">Table 3</a></caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Bit</th>
              <th class="text-left" rowspan="1" colspan="1">Name</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">H-flag</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 8801</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">1</td>
              <td class="text-left" rowspan="1" colspan="1">L-flag</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 8801</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">2</td>
              <td class="text-left" rowspan="1" colspan="1">R-flag</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 8801</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">3-11</td>
              <td class="text-left" rowspan="1" colspan="1">Unassigned</td>
              <td class="text-left" rowspan="1" colspan="1"></td>
            </tr>
          </tbody>
        </table>
</div>
<p id="section-8.4-3">Since these flags apply to an IPv6 Router Advertisement Option,
        IANA has placed this registry under the existing "Internet
        Control Message Protocol version 6 (ICMPv6) Parameters" registry and
        provided a link on the new "Provisioning Domains (PvDs)" registry.<a href="#section-8.4-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="pvd-json-media-type-registration">
<section id="section-8.5">
        <h3 id="name-pvd-json-media-type-registr">
<a href="#section-8.5" class="section-number selfRef">8.5. </a><a href="#name-pvd-json-media-type-registr" class="section-name selfRef">PvD JSON Media Type Registration</a>
        </h3>
<p id="section-8.5-1">This document registers the media type for PvD JSON text,
"application/pvd+json".<a href="#section-8.5-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-8.5-2">
          <dt id="section-8.5-2.1">Type name:</dt>
          <dd id="section-8.5-2.2">application<a href="#section-8.5-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.3">Subtype name:</dt>
          <dd id="section-8.5-2.4">pvd+json<a href="#section-8.5-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.5">Required parameters:</dt>
          <dd id="section-8.5-2.6">N/A<a href="#section-8.5-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.7">Optional parameters:</dt>
          <dd id="section-8.5-2.8">N/A<a href="#section-8.5-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.9">Encoding considerations:</dt>
          <dd id="section-8.5-2.10">Encoding considerations are
 identical to
those specified for the "application/json" media type.<a href="#section-8.5-2.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.11">Security considerations:</dt>
          <dd id="section-8.5-2.12">See <a href="#security" class="xref">Section 6</a> of RFC 8801.<a href="#section-8.5-2.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.13">Interoperability considerations:</dt>
          <dd id="section-8.5-2.14">This document specifies
 the format of
conforming messages and the interpretation thereof.<a href="#section-8.5-2.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.15">Published specification:</dt>
          <dd id="section-8.5-2.16">RFC 8801<a href="#section-8.5-2.16" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.17">Applications that use this media type:</dt>
          <dd id="section-8.5-2.18">This media type is
 intended
        to be used by networks advertising additional Provisioning Domain
        information and clients looking up such information.<a href="#section-8.5-2.18" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.19">Fragment identifier considerations:</dt>
          <dd id="section-8.5-2.20">N/A<a href="#section-8.5-2.20" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.21">Additional information:</dt>
          <dd id="section-8.5-2.22">N/A<a href="#section-8.5-2.22" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.23">Person &amp; email address to contact for further
 information:</dt>
          <dd id="section-8.5-2.24">See
Authors' Addresses section<a href="#section-8.5-2.24" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.25">Intended usage:</dt>
          <dd id="section-8.5-2.26">COMMON<a href="#section-8.5-2.26" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.27">Restrictions on usage:</dt>
          <dd id="section-8.5-2.28">N/A<a href="#section-8.5-2.28" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.29">Author:</dt>
          <dd id="section-8.5-2.30">IETF<a href="#section-8.5-2.30" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-8.5-2.31">Change controller:</dt>
          <dd id="section-8.5-2.32">IETF<a href="#section-8.5-2.32" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
</section>
</div>
<section id="section-9">
      <h2 id="name-references">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-9.1">
        <h3 id="name-normative-references">
<a href="#section-9.1" class="section-number selfRef">9.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="RFC1035">[RFC1035]</dt>
        <dd>
<span class="refAuthor">Mockapetris, P.</span>, <span class="refTitle">"Domain names - implementation and specification"</span>, <span class="seriesInfo">STD 13</span>, <span class="seriesInfo">RFC 1035</span>, <span class="seriesInfo">DOI 10.17487/RFC1035</span>, <time datetime="1987-11" class="refDate">November 1987</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc1035">https://www.rfc-editor.org/info/rfc1035</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="RFC2818">[RFC2818]</dt>
        <dd>
<span class="refAuthor">Rescorla, E.</span>, <span class="refTitle">"HTTP Over TLS"</span>, <span class="seriesInfo">RFC 2818</span>, <span class="seriesInfo">DOI 10.17487/RFC2818</span>, <time datetime="2000-05" class="refDate">May 2000</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2818">https://www.rfc-editor.org/info/rfc2818</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3339">[RFC3339]</dt>
        <dd>
<span class="refAuthor">Klyne, G.</span><span class="refAuthor"> and C. Newman</span>, <span class="refTitle">"Date and Time on the Internet: Timestamps"</span>, <span class="seriesInfo">RFC 3339</span>, <span class="seriesInfo">DOI 10.17487/RFC3339</span>, <time datetime="2002-07" class="refDate">July 2002</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3339">https://www.rfc-editor.org/info/rfc3339</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4191">[RFC4191]</dt>
        <dd>
<span class="refAuthor">Draves, R.</span><span class="refAuthor"> and D. Thaler</span>, <span class="refTitle">"Default Router Preferences and More-Specific Routes"</span>, <span class="seriesInfo">RFC 4191</span>, <span class="seriesInfo">DOI 10.17487/RFC4191</span>, <time datetime="2005-11" class="refDate">November 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4191">https://www.rfc-editor.org/info/rfc4191</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4343">[RFC4343]</dt>
        <dd>
<span class="refAuthor">Eastlake 3rd, D.</span>, <span class="refTitle">"Domain Name System (DNS) Case Insensitivity Clarification"</span>, <span class="seriesInfo">RFC 4343</span>, <span class="seriesInfo">DOI 10.17487/RFC4343</span>, <time datetime="2006-01" class="refDate">January 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4343">https://www.rfc-editor.org/info/rfc4343</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4861">[RFC4861]</dt>
        <dd>
<span class="refAuthor">Narten, T.</span><span class="refAuthor">, Nordmark, E.</span><span class="refAuthor">, Simpson, W.</span><span class="refAuthor">, and H. Soliman</span>, <span class="refTitle">"Neighbor Discovery for IP version 6 (IPv6)"</span>, <span class="seriesInfo">RFC 4861</span>, <span class="seriesInfo">DOI 10.17487/RFC4861</span>, <time datetime="2007-09" class="refDate">September 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4861">https://www.rfc-editor.org/info/rfc4861</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4941">[RFC4941]</dt>
        <dd>
<span class="refAuthor">Narten, T.</span><span class="refAuthor">, Draves, R.</span><span class="refAuthor">, and S. Krishnan</span>, <span class="refTitle">"Privacy Extensions for Stateless Address Autoconfiguration in IPv6"</span>, <span class="seriesInfo">RFC 4941</span>, <span class="seriesInfo">DOI 10.17487/RFC4941</span>, <time datetime="2007-09" class="refDate">September 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4941">https://www.rfc-editor.org/info/rfc4941</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><span class="refAuthor">, and 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="RFC6980">[RFC6980]</dt>
        <dd>
<span class="refAuthor">Gont, F.</span>, <span class="refTitle">"Security Implications of IPv6 Fragmentation with IPv6 Neighbor Discovery"</span>, <span class="seriesInfo">RFC 6980</span>, <span class="seriesInfo">DOI 10.17487/RFC6980</span>, <time datetime="2013-08" class="refDate">August 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6980">https://www.rfc-editor.org/info/rfc6980</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7493">[RFC7493]</dt>
        <dd>
<span class="refAuthor">Bray, T., Ed.</span>, <span class="refTitle">"The I-JSON Message Format"</span>, <span class="seriesInfo">RFC 7493</span>, <span class="seriesInfo">DOI 10.17487/RFC7493</span>, <time datetime="2015-03" class="refDate">March 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7493">https://www.rfc-editor.org/info/rfc7493</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><span class="refAuthor">, and 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="RFC7556">[RFC7556]</dt>
        <dd>
<span class="refAuthor">Anipko, D., Ed.</span>, <span class="refTitle">"Multiple Provisioning Domain Architecture"</span>, <span class="seriesInfo">RFC 7556</span>, <span class="seriesInfo">DOI 10.17487/RFC7556</span>, <time datetime="2015-06" class="refDate">June 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7556">https://www.rfc-editor.org/info/rfc7556</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8028">[RFC8028]</dt>
        <dd>
<span class="refAuthor">Baker, F.</span><span class="refAuthor"> and B. Carpenter</span>, <span class="refTitle">"First-Hop Router Selection by Hosts in a Multi-Prefix Network"</span>, <span class="seriesInfo">RFC 8028</span>, <span class="seriesInfo">DOI 10.17487/RFC8028</span>, <time datetime="2016-11" class="refDate">November 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8028">https://www.rfc-editor.org/info/rfc8028</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><span class="refAuthor">, and 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="RFC8259">[RFC8259]</dt>
        <dd>
<span class="refAuthor">Bray, T., Ed.</span>, <span class="refTitle">"The JavaScript Object Notation (JSON) Data Interchange Format"</span>, <span class="seriesInfo">STD 90</span>, <span class="seriesInfo">RFC 8259</span>, <span class="seriesInfo">DOI 10.17487/RFC8259</span>, <time datetime="2017-12" class="refDate">December 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8259">https://www.rfc-editor.org/info/rfc8259</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>
</dl>
</section>
<section id="section-9.2">
        <h3 id="name-informative-references">
<a href="#section-9.2" class="section-number selfRef">9.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="IANA-URN">[IANA-URN]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Uniform Resource Names (URN) Namespaces"</span>, <span>&lt;<a href="https://www.iana.org/assignments/urn-namespaces/">https://www.iana.org/assignments/urn-namespaces/</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IEEE8021X">[IEEE8021X]</dt>
        <dd>
<span class="refAuthor">IEEE</span>, <span class="refTitle">"IEEE Standard for Local and Metropolitan Area Networks -- Port-Based Network Access Control"</span>, <span class="seriesInfo">IEEE 802.1X-2020</span>, <span class="seriesInfo">DOI 10.1109/IEEESTD.2020.9018454</span>, <span>&lt;<a href="https://ieeexplore.ieee.org/document/9018454">https://ieeexplore.ieee.org/document/9018454</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.kline-mif-mpvd-api-reqs">[MPVD-API]</dt>
        <dd>
<span class="refAuthor">Kline, E.</span>, <span class="refTitle">"Multiple Provisioning Domains API Requirements"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-kline-mif-mpvd-api-reqs-00</span>, <time datetime="2015-11-01" class="refDate">1 November 2015</time>, <span>&lt;<a href="https://tools.ietf.org/html/draft-kline-mif-mpvd-api-reqs-00">https://tools.ietf.org/html/draft-kline-mif-mpvd-api-reqs-00</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.stenberg-mif-mpvd-dns">[MPVD-DNS]</dt>
        <dd>
<span class="refAuthor">Stenberg, M.</span><span class="refAuthor"> and S. Barth</span>, <span class="refTitle">"Multiple Provisioning Domains using Domain Name System"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-stenberg-mif-mpvd-dns-00</span>, <time datetime="2015-10-15" class="refDate">15 October 2015</time>, <span>&lt;<a href="https://tools.ietf.org/html/draft-stenberg-mif-mpvd-dns-00">https://tools.ietf.org/html/draft-stenberg-mif-mpvd-dns-00</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2131">[RFC2131]</dt>
        <dd>
<span class="refAuthor">Droms, R.</span>, <span class="refTitle">"Dynamic Host Configuration Protocol"</span>, <span class="seriesInfo">RFC 2131</span>, <span class="seriesInfo">DOI 10.17487/RFC2131</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2131">https://www.rfc-editor.org/info/rfc2131</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3646">[RFC3646]</dt>
        <dd>
<span class="refAuthor">Droms, R., Ed.</span>, <span class="refTitle">"DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"</span>, <span class="seriesInfo">RFC 3646</span>, <span class="seriesInfo">DOI 10.17487/RFC3646</span>, <time datetime="2003-12" class="refDate">December 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3646">https://www.rfc-editor.org/info/rfc3646</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3971">[RFC3971]</dt>
        <dd>
<span class="refAuthor">Arkko, J., Ed.</span><span class="refAuthor">, Kempf, J.</span><span class="refAuthor">, Zill, B.</span><span class="refAuthor">, and P. Nikander</span>, <span class="refTitle">"SEcure Neighbor Discovery (SEND)"</span>, <span class="seriesInfo">RFC 3971</span>, <span class="seriesInfo">DOI 10.17487/RFC3971</span>, <time datetime="2005-03" class="refDate">March 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3971">https://www.rfc-editor.org/info/rfc3971</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4389">[RFC4389]</dt>
        <dd>
<span class="refAuthor">Thaler, D.</span><span class="refAuthor">, Talwar, M.</span><span class="refAuthor">, and C. Patel</span>, <span class="refTitle">"Neighbor Discovery Proxies (ND Proxy)"</span>, <span class="seriesInfo">RFC 4389</span>, <span class="seriesInfo">DOI 10.17487/RFC4389</span>, <time datetime="2006-04" class="refDate">April 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4389">https://www.rfc-editor.org/info/rfc4389</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6105">[RFC6105]</dt>
        <dd>
<span class="refAuthor">Levy-Abegnoli, E.</span><span class="refAuthor">, Van de Velde, G.</span><span class="refAuthor">, Popoviciu, C.</span><span class="refAuthor">, and J. Mohacsi</span>, <span class="refTitle">"IPv6 Router Advertisement Guard"</span>, <span class="seriesInfo">RFC 6105</span>, <span class="seriesInfo">DOI 10.17487/RFC6105</span>, <time datetime="2011-02" class="refDate">February 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6105">https://www.rfc-editor.org/info/rfc6105</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6125">[RFC6125]</dt>
        <dd>
<span class="refAuthor">Saint-Andre, P.</span><span class="refAuthor"> and 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="RFC6146">[RFC6146]</dt>
        <dd>
<span class="refAuthor">Bagnulo, M.</span><span class="refAuthor">, Matthews, P.</span><span class="refAuthor">, and 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="RFC6147">[RFC6147]</dt>
        <dd>
<span class="refAuthor">Bagnulo, M.</span><span class="refAuthor">, Sullivan, A.</span><span class="refAuthor">, Matthews, P.</span><span class="refAuthor">, and I. van Beijnum</span>, <span class="refTitle">"DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers"</span>, <span class="seriesInfo">RFC 6147</span>, <span class="seriesInfo">DOI 10.17487/RFC6147</span>, <time datetime="2011-04" class="refDate">April 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6147">https://www.rfc-editor.org/info/rfc6147</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6296">[RFC6296]</dt>
        <dd>
<span class="refAuthor">Wasserman, M.</span><span class="refAuthor"> and 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="RFC6960">[RFC6960]</dt>
        <dd>
<span class="refAuthor">Santesson, S.</span><span class="refAuthor">, Myers, M.</span><span class="refAuthor">, Ankney, R.</span><span class="refAuthor">, Malpani, A.</span><span class="refAuthor">, Galperin, S.</span><span class="refAuthor">, and C. Adams</span>, <span class="refTitle">"X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP"</span>, <span class="seriesInfo">RFC 6960</span>, <span class="seriesInfo">DOI 10.17487/RFC6960</span>, <time datetime="2013-06" class="refDate">June 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6960">https://www.rfc-editor.org/info/rfc6960</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7049">[RFC7049]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span><span class="refAuthor"> and P. Hoffman</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR)"</span>, <span class="seriesInfo">RFC 7049</span>, <span class="seriesInfo">DOI 10.17487/RFC7049</span>, <time datetime="2013-10" class="refDate">October 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7049">https://www.rfc-editor.org/info/rfc7049</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7278">[RFC7278]</dt>
        <dd>
<span class="refAuthor">Byrne, C.</span><span class="refAuthor">, Drown, D.</span><span class="refAuthor">, and A. Vizdal</span>, <span class="refTitle">"Extending an IPv6 /64 Prefix from a Third Generation Partnership Project (3GPP) Mobile Interface to a LAN Link"</span>, <span class="seriesInfo">RFC 7278</span>, <span class="seriesInfo">DOI 10.17487/RFC7278</span>, <time datetime="2014-06" class="refDate">June 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7278">https://www.rfc-editor.org/info/rfc7278</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7540">[RFC7540]</dt>
        <dd>
<span class="refAuthor">Belshe, M.</span><span class="refAuthor">, Peon, R.</span><span class="refAuthor">, and M. Thomson, Ed.</span>, <span class="refTitle">"Hypertext Transfer Protocol Version 2 (HTTP/2)"</span>, <span class="seriesInfo">RFC 7540</span>, <span class="seriesInfo">DOI 10.17487/RFC7540</span>, <time datetime="2015-05" class="refDate">May 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7540">https://www.rfc-editor.org/info/rfc7540</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8106">[RFC8106]</dt>
        <dd>
<span class="refAuthor">Jeong, J.</span><span class="refAuthor">, Park, S.</span><span class="refAuthor">, Beloeil, L.</span><span class="refAuthor">, and S. Madanapalli</span>, <span class="refTitle">"IPv6 Router Advertisement Options for DNS Configuration"</span>, <span class="seriesInfo">RFC 8106</span>, <span class="seriesInfo">DOI 10.17487/RFC8106</span>, <time datetime="2017-03" class="refDate">March 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8106">https://www.rfc-editor.org/info/rfc8106</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8415">[RFC8415]</dt>
      <dd>
<span class="refAuthor">Mrugalski, T.</span><span class="refAuthor">, Siodelski, M.</span><span class="refAuthor">, Volz, B.</span><span class="refAuthor">, Yourtchenko, A.</span><span class="refAuthor">, Richardson, M.</span><span class="refAuthor">, Jiang, S.</span><span class="refAuthor">, Lemon, T.</span><span class="refAuthor">, and T. Winters</span>, <span class="refTitle">"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"</span>, <span class="seriesInfo">RFC 8415</span>, <span class="seriesInfo">DOI 10.17487/RFC8415</span>, <time datetime="2018-11" class="refDate">November 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8415">https://www.rfc-editor.org/info/rfc8415</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="acknowledgments">
<section id="section-appendix.a">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="section-appendix.a-1">Many thanks to <span class="contact-name">Markus Stenberg</span> and <span class="contact-name">Steven Barth</span> for their earlier work on <span>[<a href="#I-D.stenberg-mif-mpvd-dns" class="xref">MPVD-DNS</a>]</span>, as well as to
      <span class="contact-name">Basile Bruneau</span>, who was author of an early draft
      version
      of this document.<a href="#section-appendix.a-1" class="pilcrow">¶</a></p>
<p id="section-appendix.a-2">Thanks also to <span class="contact-name">Marcus Keane</span>, <span class="contact-name">Mikael Abrahamsson</span>, <span class="contact-name">Ray Bellis</span>,
      <span class="contact-name">Zhen Cao</span>, <span class="contact-name">Tim Chown</span>,
      <span class="contact-name">Lorenzo Colitti</span>, <span class="contact-name">Michael Di       Bartolomeo</span>, <span class="contact-name">Ian Farrer</span>, <span class="contact-name">Phillip Hallam-Baker</span>, <span class="contact-name">Bob Hinden</span>,
      <span class="contact-name">Tatuya Jinmei</span>, <span class="contact-name">Erik Kline</span>,
      <span class="contact-name">Ted Lemon</span>, <span class="contact-name">Paul Hoffman</span>,
      <span class="contact-name">Dave Thaler</span>, <span class="contact-name">Suresh       Krishnan</span>, <span class="contact-name">Gorry Fairhurst</span>, <span class="contact-name">Jen Lenkova</span>, <span class="contact-name">Veronika McKillop</span>,
      <span class="contact-name">Mark Townsley</span>, and <span class="contact-name">James       Woodyatt</span> for useful and interesting discussions and reviews.<a href="#section-appendix.a-2" class="pilcrow">¶</a></p>
<p id="section-appendix.a-3">Finally, special thanks to <span class="contact-name">Thierry Danis</span> for
      his valuable input and implementation efforts, <span class="contact-name">Tom       Jones</span> for his integration effort into the NEAT project, and <span class="contact-name">Rigil Salim</span> for his implementation work.<a href="#section-appendix.a-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="section-appendix.b">
      <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">Pierre Pfister</span></div>
<div dir="auto" class="left"><span class="org">Cisco</span></div>
<div dir="auto" class="left"><span class="street-address">11 Rue Camille Desmoulins</span></div>
<div dir="auto" class="left">
<span class="postal-code">92130</span> <span class="locality">Issy-les-Moulineaux</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ppfister@cisco.com" class="email">ppfister@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Éric Vyncke</span></div>
<div dir="auto" class="left"><span class="org">Cisco</span></div>
<div dir="auto" class="left"><span class="street-address">De Kleetlaan, 6</span></div>
<div dir="auto" class="left">
<span class="postal-code">1831</span> <span class="locality">Diegem</span>
</div>
<div dir="auto" class="left"><span class="country-name">Belgium</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:evyncke@cisco.com" class="email">evyncke@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Tommy Pauly</span></div>
<div dir="auto" class="left"><span class="org">Apple Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">One Apple Park Way</span></div>
<div dir="auto" class="left">
<span class="locality">Cupertino</span>, <span class="region">California</span> <span class="postal-code">95014</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:tpauly@apple.com" class="email">tpauly@apple.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">David Schinazi</span></div>
<div dir="auto" class="left"><span class="org">Google LLC</span></div>
<div dir="auto" class="left"><span class="street-address">1600 Amphitheatre Parkway</span></div>
<div dir="auto" class="left">
<span class="locality">Mountain
   View</span>, <span class="region">California</span> <span class="postal-code">94043</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:dschinazi.ietf@gmail.com" class="email">dschinazi.ietf@gmail.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Wenqin Shao</span></div>
<div dir="auto" class="left"><span class="org">Cisco</span></div>
<div dir="auto" class="left"><span class="street-address">11 Rue Camille Desmoulins</span></div>
<div dir="auto" class="left">
<span class="postal-code">92130</span> <span class="locality">Issy-les-Moulineaux</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:wenshao@cisco.com" class="email">wenshao@cisco.com</a>
</div>
</address>
</section>
</div>
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