File: rfc9294.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 9294: Application-Specific Link Attributes Advertisement Using the Border Gateway Protocol - Link State (BGP‑LS)</title>
<meta content="Ketan Talaulikar" name="author">
<meta content="Peter Psenak" name="author">
<meta content="Jeff Tantsura" name="author">
<meta content="
       Extensions have been defined for link-state routing protocols that
      enable distribution of application-specific link attributes for existing
      as well as newer applications such as Segment Routing (SR). This document
      defines extensions to the Border Gateway Protocol - Link State (BGP-LS) to enable the advertisement of these
      application-specific attributes as a part of the topology information
      from the network. 
    " name="description">
<meta content="xml2rfc 3.14.0" name="generator">
<meta content="BGP-LS" name="keyword">
<meta content="Segment Routing" name="keyword">
<meta content="IS-IS" name="keyword">
<meta content="OSPF" name="keyword">
<meta content="OSPFv3" name="keyword">
<meta content="9294" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.14.0
    Python 3.9.13
    appdirs 1.4.4
    ConfigArgParse 1.5.3
    google-i18n-address 2.5.1
    html5lib 1.1
    intervaltree 3.1.0
    Jinja2 3.1.2
    kitchen 1.2.6
    lxml 4.9.0
    MarkupSafe 2.1.1
    pycountry 22.3.5
    PyYAML 6.0
    requests 2.28.0
    setuptools 44.1.1
    six 1.16.0
    weasyprint 56.1
-->
<link href="rfc9294.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 {
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}
h1 {
  font-size: 26px;
  margin: 1em 0;
}
h2 {
  font-size: 22px;
  margin-top: -20px;  /* provide offset for in-page anchors */
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}
h3 {
  font-size: 18px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
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h4 {
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  padding-top: 42px;
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h5, h6 {
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}
#n-copyright-notice {
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/* general structure */
p {
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}
div, span {
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}
div {
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.alignRight.art-text pre {
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.alignRight {
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}
.alignRight > *:first-child {
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}
.alignRight > *:nth-child(2) {
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}
svg {
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}
.alignCenter.art-text {
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  border: 1px solid #eee;
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.alignCenter.art-text pre {
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.alignCenter {
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/* lists */
ol, ul {
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}
ol ol, ul ul, ol ul, ul ol {
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li {
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.ulCompact li {
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ul.empty, .ulEmpty {
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}
ul.empty li, .ulEmpty li {
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ul.ulBare, li.ulBare {
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}
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 {
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}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
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}
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 {
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  font-family: 'Roboto Mono', monospace;
}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
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}
figure {
  margin: 0;
}
figure blockquote {
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}
figcaption {
  font-style: italic;
  margin: 0 0 1em 0;
}
@media screen {
  pre {
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    max-width: 100%;
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}

/* aside, blockquote */
aside, blockquote {
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  padding: 1.2em 2em;
}
blockquote {
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  color: #111; /* Arlen: WCAG 2019 */
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  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 {
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}
tr:nth-child(2n+1) > td {
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}
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. */
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}

/* pilcrow */
a.pilcrow {
  color: #666; /* Arlen: AHDJ 2019 */
  text-decoration: none;
  visibility: hidden;
  user-select: none;
  -ms-user-select: none;
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  -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;
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  a.pilcrow:hover {
    background-color: transparent;
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}

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

.role {
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}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
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  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
/* Fix PDF info block run off issue */
@media print {
  #identifiers dd {
    float: none;
  }
}
#identifiers .authors .author {
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  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;
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}

/* 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;
  }
  pre.breakable {
    break-inside: auto;
  }
  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 {
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  @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;
}
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<table class="ears">
<thead><tr>
<td class="left">RFC 9294</td>
<td class="center">App-Specific Link Attributes Using BGP-L</td>
<td class="right">August 2022</td>
</tr></thead>
<tfoot><tr>
<td class="left">Talaulikar, 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/rfc9294" class="eref">9294</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="2022-08" class="published">August 2022</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">K. Talaulikar, <span class="editor">Ed.</span>
</div>
<div class="org">Arrcus Inc.</div>
</div>
<div class="author">
      <div class="author-name">P. Psenak</div>
<div class="org">Cisco Systems</div>
</div>
<div class="author">
      <div class="author-name">J. Tantsura</div>
<div class="org">Microsoft</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9294</h1>
<h1 id="title">Application-Specific Link Attributes Advertisement Using the Border Gateway Protocol - Link State (BGP‑LS)</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">Extensions have been defined for link-state routing protocols that
      enable distribution of application-specific link attributes for existing
      as well as newer applications such as Segment Routing (SR). This document
      defines extensions to the Border Gateway Protocol - Link State (BGP-LS) to enable the advertisement of these
      application-specific attributes as a part of the topology information
      from the network.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This is an Internet Standards Track document.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
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</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2022 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Revised BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Revised 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="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" 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-requirements-language" class="xref">Requirements Language</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" 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-application-specific-link-a" class="xref">Application-Specific Link Attributes TLV</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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-application-specific-link-att" class="xref">Application-Specific Link Attributes</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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-procedures" class="xref">Procedures</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" 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-illustration-for-is-is" class="xref">Illustration for IS-IS</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" 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-deployment-considerations" class="xref">Deployment Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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-iana-considerations" class="xref">IANA Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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-manageability-consideration" class="xref">Manageability Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" 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></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" 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></p>
</li>
              <li class="compact toc ulBare ulEmpty" 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></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#appendix-A" class="xref"></a><a href="#name-acknowledgements" class="xref">Acknowledgements</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#appendix-B" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="INTRO">
<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">The Border Gateway Protocol - Link State (BGP-LS) <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span> enables the distribution of
      the link-state topology information from link-state routing protocols
      (viz., IS-IS <span>[<a href="#RFC1195" class="xref">RFC1195</a>]</span>, OSPFv2 <span>[<a href="#RFC2328" class="xref">RFC2328</a>]</span>,
      and OSPFv3 <span>[<a href="#RFC5340" class="xref">RFC5340</a>]</span>) to an application like a controller
      or Path Computation Engine (PCE) via BGP. The controller or PCE gets the
      end-to-end topology information across IGP domains so it can perform
      path computations for use cases like end-to-end traffic engineering
      (TE).<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">The link-state topology information distributed via BGP-LS includes
      link attributes that were originally defined for MPLS TE (i.e., using RSVP-TE <span>[<a href="#RFC3209" class="xref">RFC3209</a>]</span> or GMPLS <span>[<a href="#RFC4202" class="xref">RFC4202</a>]</span> applications). In recent years, applications,
      such as Segment Routing (SR) Policy <span>[<a href="#RFC8402" class="xref">RFC8402</a>]</span> and
      Loop-Free Alternates (LFA) <span>[<a href="#RFC5286" class="xref">RFC5286</a>]</span>, which also make use
      of link attributes, have been introduced. <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> and
      <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span> define extensions for IS-IS and OSPF,
      respectively, that enable advertising application-specific link
      attributes for these and other future applications. This has resulted in
      the need for a similar BGP-LS extension to include this additional
      link-state topology information from the link-state routing
      protocols.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">This document defines the BGP-LS extensions for the advertisement of
      application-specific link attributes. It describes the advertisement of
      these link attributes as top-level TLVs (i.e., as TLVs of the BGP-LS
      Attribute) and as sub-TLVs of the (top-level) Application-Specific Link
      Attributes (ASLA) TLV. The document also describes the procedures for the
      advertisement of these attributes from the underlying IGPs and discusses
      their deployment aspects.<a href="#section-1-3" class="pilcrow">¶</a></p>
<section id="section-1.1">
        <h3 id="name-requirements-language">
<a href="#section-1.1" class="section-number selfRef">1.1. </a><a href="#name-requirements-language" class="section-name selfRef">Requirements Language</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>
</section>
</div>
<div id="ASLATLV">
<section id="section-2">
      <h2 id="name-application-specific-link-a">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-application-specific-link-a" class="section-name selfRef">Application-Specific Link Attributes TLV</a>
      </h2>
<p id="section-2-1">BGP-LS <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span> specifies the Link Network Layer
      Reachability Information (NLRI) for the advertisement of links and their
      attributes using the BGP-LS Attribute. The ASLA TLV is an optional top-level BGP-LS Attribute TLV that
      is introduced for Link NLRIs. It is defined such that it may act as a
      container for certain existing and future link attributes that require
      application-specific definition.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">The format of this TLV is as follows and is similar to the
      corresponding ASLA sub-TLVs defined for OSPF and IS-IS in <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span> and <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span>, respectively.<a href="#section-2-2" class="pilcrow">¶</a></p>
<span id="name-application-specific-link-at"></span><div id="ASLA-TLV">
<figure id="figure-1">
        <div class="alignCenter art-text artwork" id="section-2-3.1">
<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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | SABM Length   | UDABM Length  |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Standard Application Identifier Bit Mask (variable)      //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    User-Defined Application Identifier Bit Mask (variable)   //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Link Attribute sub-TLVs                 //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-application-specific-link-at" class="selfRef">Application-Specific Link Attributes TLV</a>
        </figcaption></figure>
</div>
<p id="section-2-4">where:<a href="#section-2-4" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-2-5">
        <dt id="section-2-5.1">Type:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.2">1122<a href="#section-2-5.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.3">Length:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.4">variable<a href="#section-2-5.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.5">SABM Length:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.6">1-octet field that carries the Standard Application
          Identifier Bit Mask Length in octets as defined in <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>.<a href="#section-2-5.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.7">UDABM Length:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.8">1-octet field that carries the User-Defined
          Application Identifier Bit Mask Length in octets as defined in <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>.<a href="#section-2-5.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.9">Reserved:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.10">2-octet field that <span class="bcp14">MUST</span> be set to zero on transmission
          and <span class="bcp14">MUST</span> be ignored on reception.<a href="#section-2-5.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.11">Standard Application Identifier Bit Mask:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.12">An optional set of
          bits (of size 0, 4, or 8 octets as indicated by the SABM Length),
          where each bit represents a single standard application as defined
          in <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span>.<a href="#section-2-5.12" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.13">User-Defined Application Identifier Bit Mask:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.14">An optional set of
          bits (of size 0, 4, or 8 octets as indicated by the UDABM Length),
          where each bit represents a single user-defined application as
          defined in <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> and <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>.<a href="#section-2-5.14" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-5.15">Link Attribute sub-TLVs:</dt>
        <dd style="margin-left: 1.5em" id="section-2-5.16">BGP-LS Attribute TLVs corresponding to
          the Link NLRI that are application-specific (including existing ones
          as specified in <a href="#APPSPECATTRS" class="xref">Section 3</a>) are included as
          sub-TLVs of the ASLA TLV.<a href="#section-2-5.16" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
<p id="section-2-6">The semantics associated with the standard and user-defined bit masks
      as well as the encoding scheme for application-specific attributes are
      as specified in <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>.<a href="#section-2-6" class="pilcrow">¶</a></p>
<p id="section-2-7">The ASLA TLV and its sub-TLVs can only be added to the BGP-LS
      Attribute associated with the Link NLRI of the node that originates the
      underlying IGP link attribute TLVs and sub-TLVs. The procedures for
      originating link attributes in the ASLA TLV from underlying IGPs are
      specified in <a href="#PROCEDURES" class="xref">Section 4</a>.<a href="#section-2-7" class="pilcrow">¶</a></p>
</section>
</div>
<div id="APPSPECATTRS">
<section id="section-3">
      <h2 id="name-application-specific-link-att">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-application-specific-link-att" class="section-name selfRef">Application-Specific Link Attributes</a>
      </h2>
<p id="section-3-1">Several BGP-LS Attribute TLVs corresponding to the Link NLRI are
      defined in BGP-LS <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>, and more may be added in the future. Those attributes
      that have been determined to be, and advertised as, application-specific
      in the underlying IGPs are also encoded similarly in BGP-LS.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">The following table lists the currently defined BGP-LS Attribute
      TLVs corresponding to Link NLRI that can have application-specific
      semantics based on the underlying IGP specifications <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>. These were originally
      defined with semantics for RSVP-TE and GMPLS applications in BGP-LS by
      the respective reference documents.<a href="#section-3-2" class="pilcrow">¶</a></p>
<span id="name-existing-bgp-ls-tlvs-identi"></span><div id="APPSPECATTR">
<table class="center" id="table-1">
        <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-existing-bgp-ls-tlvs-identi" class="selfRef">Existing BGP-LS TLVs Identified as Application-Specific</a>
        </caption>
<thead>
          <tr>
            <th class="text-center" rowspan="1" colspan="1">TLV Code Point</th>
            <th class="text-left" rowspan="1" colspan="1">Description</th>
            <th class="text-left" rowspan="1" colspan="1">Reference Document</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1088</td>
            <td class="text-left" rowspan="1" colspan="1">Administrative group (color)</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1092</td>
            <td class="text-left" rowspan="1" colspan="1">TE Default Metric</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1096</td>
            <td class="text-left" rowspan="1" colspan="1">Shared Risk Link Group</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1114</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Link Delay</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1115</td>
            <td class="text-left" rowspan="1" colspan="1">Min/Max Unidirectional Link Delay</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1116</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Delay Variation</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1117</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Link Loss</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1118</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Residual Bandwidth</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1119</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Available Bandwidth</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1120</td>
            <td class="text-left" rowspan="1" colspan="1">Unidirectional Utilized Bandwidth</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>
</td>
          </tr>
          <tr>
            <td class="text-center" rowspan="1" colspan="1">1173</td>
            <td class="text-left" rowspan="1" colspan="1">Extended Administrative Group</td>
            <td class="text-left" rowspan="1" colspan="1">
              <span>[<a href="#RFC9104" class="xref">RFC9104</a>]</span>
</td>
          </tr>
        </tbody>
      </table>
</div>
<p id="section-3-4">All the BGP-LS Attribute TLVs listed in the table above are <span class="bcp14">REQUIRED</span>
      to be advertised as a top-level TLV in the BGP-LS Attribute when used to
      carry link attributes specific to RSVP-TE.<a href="#section-3-4" class="pilcrow">¶</a></p>
<p id="section-3-5">BGP-LS Attribute TLVs corresponding to Link NLRI that are advertised
      in the underlying IGP as application-specific are <span class="bcp14">REQUIRED</span> to be encoded
      within an ASLA TLV.<a href="#section-3-5" class="pilcrow">¶</a></p>
<p id="section-3-6">Link attributes that do not have application-specific semantics <span class="bcp14">MUST NOT</span> be advertised within the ASLA TLV.<a href="#section-3-6" class="pilcrow">¶</a></p>
<p id="section-3-7">When the same application-specific link attributes are advertised
      both within the ASLA TLV and as top-level TLVs in the BGP-LS Attribute,
      the attributes advertised within the ASLA TLV take precedence for the
      applications indicated in the ASLA TLV encoding.<a href="#section-3-7" class="pilcrow">¶</a></p>
</section>
</div>
<div id="PROCEDURES">
<section id="section-4">
      <h2 id="name-procedures">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-procedures" class="section-name selfRef">Procedures</a>
      </h2>
<p id="section-4-1">The BGP-LS originator learns of the association of an
      application-specific attribute to one or more applications from the
      underlying IGP protocol Link State Advertisements (LSAs) or Link State Packets (LSPs) from which it is advertising the
      topology information. <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span> and <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> specify the mechanisms for advertising
      application-specific link attributes in OSPF and IS-IS, respectively.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">Application-specific link attributes received from an IGP node
      without the use of ASLA encodings continue to be encoded using the
      respective BGP-LS top-level TLVs listed in <a href="#APPSPECATTR" class="xref">Table 1</a>
      as specified in their respective reference documents.<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3">While the ASLA encoding in OSPF is similar to that of BGP-LS, the
      encoding in IS-IS differs and requires additional procedures when
      conveying information into BGP-LS. One of these differences arises from
      the presence of the L-flag in the IS-IS encoding. Another difference
      arises due to the requirement to collate information from two types of
      IS-IS encodings for application-specific link information (i.e., the
      IS-IS ASLA sub-TLV and the IS-IS Application-Specific Shared Risk Link Group (SRLG) TLV) <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> and to carry them together in the BGP-LS ASLA
      TLV.<a href="#section-4-3" class="pilcrow">¶</a></p>
<p id="section-4-4">A BGP-LS originator node that is advertising link-state information
      from the underlying IGP using ASLA encodings determines their BGP-LS
      encoding based on the following rules:<a href="#section-4-4" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4-5">
<li id="section-4-5.1">Application-specific link attributes received from an OSPF node
          using an ASLA sub-TLV or from an IS-IS node using either an ASLA sub-TLV
          or an Application-Specific SRLG TLV <span class="bcp14">MUST</span> be encoded in the BGP-LS ASLA
          TLV as sub-TLVs. Exceptions to this rule are specified in (2)(F) and
          (2)(G) below.<a href="#section-4-5.1" class="pilcrow">¶</a>
</li>
        <li id="section-4-5.2">
          <p id="section-4-5.2.1">In the case of IS-IS, the specific procedures below are to be
          followed:<a href="#section-4-5.2.1" class="pilcrow">¶</a></p>
<ol start="1" type="A" class="normal type-A" id="section-4-5.2.2">
<li id="section-4-5.2.2.1">When application-specific link attributes are received from a
              node with the L-flag set in the IS-IS ASLA sub-TLV and when
              application bits (other than RSVP-TE) are set in the application
              bit masks, then the application-specific link attributes
              advertised in the corresponding legacy IS-IS TLVs and sub-TLVs <span class="bcp14">MUST</span>
              be encoded within the BGP-LS ASLA TLV as sub-TLVs with the
              application bits (other than the RSVP-TE bit) copied from the
              IS-IS ASLA sub-TLV. The link attributes advertised in the legacy
              IS-IS TLVs and sub-TLVs are also advertised in BGP-LS top-level TLVs
              as per <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>, <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>, and <span>[<a href="#RFC9104" class="xref">RFC9104</a>]</span>. The same procedure also applies for the
              advertisement of the SRLG values from the IS-IS
              Application-Specific SRLG TLV.<a href="#section-4-5.2.2.1" class="pilcrow">¶</a>
</li>
            <li id="section-4-5.2.2.2">When the IS-IS ASLA sub-TLV has the RSVP-TE application bit
              set, then the link attributes for the corresponding IS-IS ASLA
              sub-TLVs <span class="bcp14">MUST</span> be encoded using the respective BGP-LS top-level
              TLVs as per <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>, <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>, and
              <span>[<a href="#RFC9104" class="xref">RFC9104</a>]</span>. Similarly, when the IS-IS
              Application-Specific SRLG TLV has the RSVP-TE application bit
              set, then the SRLG values within it <span class="bcp14">MUST</span> be encoded using the
              top-level BGP-LS SRLG TLV (1096) as per <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>.<a href="#section-4-5.2.2.2" class="pilcrow">¶</a>
</li>
            <li id="section-4-5.2.2.3">
              <p id="section-4-5.2.2.3.1">The SRLGs advertised in one or more IS-IS Application-Specific SRLG
              TLVs and the other link attributes advertised in one or more IS-IS ASLA
              sub-TLVs are <span class="bcp14">REQUIRED</span> to be collated, on a per-application
              basis, only for those applications that meet all the following
              criteria:<a href="#section-4-5.2.2.3.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4-5.2.2.3.2.1">their bit is set in the SABM or UDABM in one of the two
                  types of IS-IS encodings (e.g., IS-IS ASLA sub-TLV)<a href="#section-4-5.2.2.3.2.1" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-4-5.2.2.3.2.2">the other encoding type (e.g., IS-IS Application Specific
                  SRLG TLV) has an advertisement with zero-length application
                  bit masks<a href="#section-4-5.2.2.3.2.2" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-4-5.2.2.3.2.3">there is no corresponding advertisement of that other
                  encoding type (following the example, IS-IS Application
                  Specific SRLG TLV) with that specific application bit
                  set<a href="#section-4-5.2.2.3.2.3" class="pilcrow">¶</a>
</li>
              </ul>
<p id="section-4-5.2.2.3.3">For each such application, its collated information
              <span class="bcp14">MUST</span> be carried in a BGP-LS ASLA TLV with that application's bit
              set in the SABM or UDABM. See the illustration in <a href="#EXAMPLE" class="xref">Section 4.1</a>.<a href="#section-4-5.2.2.3.3" class="pilcrow">¶</a></p>
</li>
            <li id="section-4-5.2.2.4">If the resulting set of collated link attributes and SRLG
              values is common across multiple applications, they <span class="bcp14">MAY</span> be
              advertised in a common BGP-LS ASLA TLV instance where the bits
              for all such applications would be set in the application bit
              mask.<a href="#section-4-5.2.2.4" class="pilcrow">¶</a>
</li>
            <li id="section-4-5.2.2.5">Both the SRLG values from IS-IS Application-Specific SRLG
              TLVs and the link attributes from IS-IS ASLA sub-TLVs, with the
              zero-length application bit mask, <span class="bcp14">MUST</span> be advertised into a
              BGP-LS ASLA TLV with a zero-length application bit mask,
              independent of the collation described above.<a href="#section-4-5.2.2.5" class="pilcrow">¶</a>
</li>
            <li id="section-4-5.2.2.6">
              <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> allows the advertisement of the
              Maximum Link Bandwidth within an IS-IS ASLA sub-TLV even though
              it is not an application-specific attribute. However, when
              originating the Maximum Link Bandwidth into BGP-LS, the
              attribute <span class="bcp14">MUST</span> be encoded only in the top-level BGP-LS Maximum
              Link Bandwidth TLV (1089) and <span class="bcp14">MUST NOT</span> be advertised within the
              BGP-LS ASLA TLV.<a href="#section-4-5.2.2.6" class="pilcrow">¶</a>
</li>
            <li id="section-4-5.2.2.7">
              <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> also allows the advertisement of the
              Maximum Reservable Link Bandwidth and the Unreserved Bandwidth
              within an IS-IS ASLA sub-TLV even though these attributes are
              specific to RSVP-TE application. However, when originating the
              Maximum Reservable Link Bandwidth and Unreserved Bandwidth into
              BGP-LS, these attributes <span class="bcp14">MUST</span> be encoded only in the BGP-LS
              top-level Maximum Reservable Link Bandwidth TLV (1090) and
              Unreserved Bandwidth TLV (1091), respectively, and not within the
              BGP-LS ASLA TLV.<a href="#section-4-5.2.2.7" class="pilcrow">¶</a>
</li>
          </ol>
</li>
      </ol>
<p id="section-4-6">These rules ensure that a BGP-LS originator performs the
      advertisement for all application-specific link attributes from the IGP
      nodes that support the ASLA extension. Furthermore, it also ensures that
      the top-level BGP-LS TLVs defined for RSVP-TE and GMPLS applications
      continue to be used for advertisement of their application-specific
      attributes.<a href="#section-4-6" class="pilcrow">¶</a></p>
<p id="section-4-7">A BGP-LS speaker would normally advertise all the
      application-specific link attributes corresponding to RSVP-TE and GMPLS
      applications as existing top-level BGP-LS TLVs while for other
      applications they are encoded in the ASLA TLV(s) with appropriate applicable
      bit mask setting. An application-specific attribute value received via a
      sub-TLV within the ASLA TLV has precedence over the value received via a
      top-level TLV.<a href="#section-4-7" class="pilcrow">¶</a></p>
<div id="EXAMPLE">
<section id="section-4.1">
        <h3 id="name-illustration-for-is-is">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-illustration-for-is-is" class="section-name selfRef">Illustration for IS-IS</a>
        </h3>
<p id="section-4.1-1">This section illustrates the procedure for the advertisement of
        application-specific link attributes from IS-IS into BGP-LS.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">Consider the following advertisements for a link in IS-IS. We start
        with this set:<a href="#section-4.1-2" class="pilcrow">¶</a></p>
<ol start="1" type="a" class="normal type-a" id="section-4.1-3">
<li id="section-4.1-3.1">IS-IS ASLA sub-TLV with the S, F, and X bits set on it that carries
            certain application-specific link attributes<a href="#section-4.1-3.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-3.2">IS-IS Application-Specific SRLG TLV with zero-length bit
            masks with a set of application-specific SRLGs<a href="#section-4.1-3.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-3.3">IS-IS Application-Specific SRLG TLV with the X bit set on it
            with a set of application-specific SRLGs<a href="#section-4.1-3.3" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.1-4">The corresponding BGP-LS advertisements for that link are
        determined as follows:<a href="#section-4.1-4" class="pilcrow">¶</a></p>
<p id="section-4.1-5">First, based on rule (1), the advertisements are conveyed to BGP-LS
        to get the following "updated set":<a href="#section-4.1-5" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.1-6">
<li id="section-4.1-6.1">ASLA with the S, F, and X bits set on it that carries link attributes
            from IS-IS advertisement (a)<a href="#section-4.1-6.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-6.2">ASLA SRLG with zero-length bit masks with a set of SRLGs from
            IS-IS advertisement (b)<a href="#section-4.1-6.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-6.3">ASLA SRLG with the X bit set on it with a set of SRLGs from
            IS-IS advertisement (c)<a href="#section-4.1-6.3" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.1-7">Next, we apply the rules from (2) to this "updated set", because
        all of them were sourced from IS-IS, to derive a new set.<a href="#section-4.1-7" class="pilcrow">¶</a></p>
<p id="section-4.1-8">The next rule that applies is (2)(c), and it is determined that
        collation is required for applications S and F; therefore, we get the
        following "final set":<a href="#section-4.1-8" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.1-9">
<li id="section-4.1-9.1">ASLA with the S bit set on it that carries link attributes from
            IS-IS advertisement (a) and SRLGs from IS-IS advertisement (b)
            (this is collation for application S based on (2)(c))<a href="#section-4.1-9.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-9.2">ASLA with the F bit set on it that carries link attributes from
            IS-IS advertisement (a) and SRLGs from IS-IS advertisement (b)
            (this is collation for application F based on (2)(c))<a href="#section-4.1-9.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-9.3">ASLA with the X bit set on it that carries link attributes from
            IS-IS advertisement (a) (remaining application not affected by
            collation based on (2)(c))<a href="#section-4.1-9.3" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-9.4">ASLA with zero-length bit masks with SRLGs from IS-IS
            advertisement (b) (not affected by (2)(c) and therefore carried
            forward unchanged from the "updated set")<a href="#section-4.1-9.4" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-9.5">ASLA with the X bit set on it with SRLGs from IS-IS
            advertisement (c) (not affected by (2)(c) and therefore carried
            forward unchanged from the "updated set")<a href="#section-4.1-9.5" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.1-10">Implementations may optionally perform further consolidation by
        processing the "final set" above based on (2)(d) to determine the
        following "consolidated final set":<a href="#section-4.1-10" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.1-11">
<li id="section-4.1-11.1">ASLA with the S and F bits set on it that carries application-specific
            link attributes from IS-IS advertisement (a) and SRLGs from IS-IS
            advertisement (b) (this is the consolidation of items 1 and 2 of
            the "final set" based on (2)(d))<a href="#section-4.1-11.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-11.2">ASLA with the X bit set on it that carries certain
            application-specific link attributes from IS-IS advertisement (a)
            (it is unaffected by this consolidation)<a href="#section-4.1-11.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-11.3">ASLA with zero-length bit masks with a set of
            application-specific SRLGs from IS-IS advertisement (b) (this is
            retained based on (2)(e) and is unaffected by any further
            consolidation)<a href="#section-4.1-11.3" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-11.4">ASLA with the X bit set on it with a set of
            application-specific SRLGs from IS-IS advertisement (c) (it is
            unaffected by this consolidation)<a href="#section-4.1-11.4" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.1-12">Further optimization (e.g., combining (2) and (4) from the
        "consolidated final set" above into a single BGP-LS ASLA TLV) may be
        possible while ensuring that the semantics are preserved between the
        IS-IS and BGP-LS advertisements. Such optimizations are outside the
        scope of this document.<a href="#section-4.1-12" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="DEPLOY">
<section id="section-5">
      <h2 id="name-deployment-considerations">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-deployment-considerations" class="section-name selfRef">Deployment Considerations</a>
      </h2>
<p id="section-5-1">BGP-LS sources the link-state topology information (including the
      extensions introduced by this document) from the underlying link-state
      IGP protocols. The various deployment aspects related to the
      advertisement and use of application-specific link attributes are
      discussed in the Deployment Considerations sections of <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span> and <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span>. The IGP backward-compatibility aspects
      described in those documents associated with
      application-specific link attributes along with the BGP-LS procedures
      specified in this document enable backward compatibility in deployments
      of existing implementations of <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>, <span>[<a href="#RFC8571" class="xref">RFC8571</a>]</span>, and <span>[<a href="#RFC9104" class="xref">RFC9104</a>]</span> for applications such as
      RSVP-TE, SR Policy, and LFA.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">It is recommended that only nodes supporting this specification are
      selected as originators of BGP-LS information when advertising the
      link-state information from the IGPs in deployments supporting
      application-specific link attributes.<a href="#section-5-2" class="pilcrow">¶</a></p>
<p id="section-5-3">BGP-LS consumers that do not support this specification can continue
      to use the existing top-level TLVs for link attributes for existing
      applications as discussed above. However, they would be able to support
      neither the application-specific link attributes nor newer applications
      that may be encoded only using the ASLA TLV.<a href="#section-5-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="IANA">
<section id="section-6">
      <h2 id="name-iana-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-6-1">IANA has assigned a
      code point from the "BGP-LS Node Descriptor, Link Descriptor,
      Prefix Descriptor, and Attribute TLVs" registry as described in the following table. There is no "IS-IS TLV/Sub-TLV" value for this entry.<a href="#section-6-1" class="pilcrow">¶</a></p>
<span id="name-asla-tlv-code-point-allocat"></span><div id="code-point">
<table class="center" id="table-2">
        <caption>
<a href="#table-2" class="selfRef">Table 2</a>:
<a href="#name-asla-tlv-code-point-allocat" class="selfRef">ASLA TLV Code Point Allocation</a>
        </caption>
<thead>
          <tr>
            <th class="text-left" rowspan="1" colspan="1">TLV Code Point</th>
            <th class="text-left" rowspan="1" colspan="1">Description</th>
            <th class="text-left" rowspan="1" colspan="1">Reference</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">1122</td>
            <td class="text-left" rowspan="1" colspan="1">Application-Specific Link Attributes</td>
            <td class="text-left" rowspan="1" colspan="1">RFC 9294</td>
          </tr>
        </tbody>
      </table>
</div>
</section>
</div>
<div id="Manageability">
<section id="section-7">
      <h2 id="name-manageability-consideration">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-manageability-consideration" class="section-name selfRef">Manageability Considerations</a>
      </h2>
<p id="section-7-1">The protocol extensions introduced in this document augment the
      existing IGP topology information defined in <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>.
      Procedures and protocol extensions defined in this document do not
      affect the BGP protocol operations and management other than as
      discussed in the Manageability Considerations section of <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>. Specifically, the malformed NLRI attribute tests in
      the Fault Management section of <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span> now encompass
      the BGP-LS TLVs defined in this document.<a href="#section-7-1" class="pilcrow">¶</a></p>
<p id="section-7-2">The extensions specified in this document do not specify any new
      configuration or monitoring aspects in BGP or BGP-LS. The specification
      of BGP models is an ongoing work based on <span>[<a href="#I-D.ietf-idr-bgp-model" class="xref">IDR-BGP-MODEL</a>]</span>.<a href="#section-7-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="Security">
<section id="section-8">
      <h2 id="name-security-considerations">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-8-1">Security considerations for acquiring and distributing BGP-LS
      information are discussed in <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>. Specifically, the
      considerations related to topology information, which are related to traffic engineering, apply.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">The TLVs introduced in this document are used to propagate the
      application-specific link attributes IGP extensions defined in <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> and <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>. It is assumed that the
      IGP instances originating these TLVs will support all the required
      security (as described in <span>[<a href="#RFC8919" class="xref">RFC8919</a>]</span> and <span>[<a href="#RFC8920" class="xref">RFC8920</a>]</span>).<a href="#section-8-2" class="pilcrow">¶</a></p>
<p id="section-8-3">This document defines a new way to advertise link attributes.
      Tampering with the information defined in this document may affect
      applications using it, including impacting traffic engineering, which
      uses various link attributes for its path computation. As the
      advertisements defined in this document limit the scope to specific
      applications, the impact of tampering is similarly limited in scope. The
      advertisement of the link attribute information defined in this document
      presents no significant additional risk beyond that associated with the
      existing link attribute information already supported in <span>[<a href="#RFC7752" class="xref">RFC7752</a>]</span>.<a href="#section-8-3" class="pilcrow">¶</a></p>
</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="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="RFC7752">[RFC7752]</dt>
        <dd>
<span class="refAuthor">Gredler, H., Ed.</span>, <span class="refAuthor">Medved, J.</span>, <span class="refAuthor">Previdi, S.</span>, <span class="refAuthor">Farrel, A.</span>, and <span class="refAuthor">S. Ray</span>, <span class="refTitle">"North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP"</span>, <span class="seriesInfo">RFC 7752</span>, <span class="seriesInfo">DOI 10.17487/RFC7752</span>, <time datetime="2016-03" class="refDate">March 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7752">https://www.rfc-editor.org/info/rfc7752</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="RFC8571">[RFC8571]</dt>
        <dd>
<span class="refAuthor">Ginsberg, L., Ed.</span>, <span class="refAuthor">Previdi, S.</span>, <span class="refAuthor">Wu, Q.</span>, <span class="refAuthor">Tantsura, J.</span>, and <span class="refAuthor">C. Filsfils</span>, <span class="refTitle">"BGP - Link State (BGP-LS) Advertisement of IGP Traffic Engineering Performance Metric Extensions"</span>, <span class="seriesInfo">RFC 8571</span>, <span class="seriesInfo">DOI 10.17487/RFC8571</span>, <time datetime="2019-03" class="refDate">March 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8571">https://www.rfc-editor.org/info/rfc8571</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8919">[RFC8919]</dt>
        <dd>
<span class="refAuthor">Ginsberg, L.</span>, <span class="refAuthor">Psenak, P.</span>, <span class="refAuthor">Previdi, S.</span>, <span class="refAuthor">Henderickx, W.</span>, and <span class="refAuthor">J. Drake</span>, <span class="refTitle">"IS-IS Application-Specific Link Attributes"</span>, <span class="seriesInfo">RFC 8919</span>, <span class="seriesInfo">DOI 10.17487/RFC8919</span>, <time datetime="2020-10" class="refDate">October 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8919">https://www.rfc-editor.org/info/rfc8919</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8920">[RFC8920]</dt>
        <dd>
<span class="refAuthor">Psenak, P., Ed.</span>, <span class="refAuthor">Ginsberg, L.</span>, <span class="refAuthor">Henderickx, W.</span>, <span class="refAuthor">Tantsura, J.</span>, and <span class="refAuthor">J. Drake</span>, <span class="refTitle">"OSPF Application-Specific Link Attributes"</span>, <span class="seriesInfo">RFC 8920</span>, <span class="seriesInfo">DOI 10.17487/RFC8920</span>, <time datetime="2020-10" class="refDate">October 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8920">https://www.rfc-editor.org/info/rfc8920</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9104">[RFC9104]</dt>
      <dd>
<span class="refAuthor">Tantsura, J.</span>, <span class="refAuthor">Wang, Z.</span>, <span class="refAuthor">Wu, Q.</span>, and <span class="refAuthor">K. Talaulikar</span>, <span class="refTitle">"Distribution of Traffic Engineering Extended Administrative Groups Using the Border Gateway Protocol - Link State (BGP-LS)"</span>, <span class="seriesInfo">RFC 9104</span>, <span class="seriesInfo">DOI 10.17487/RFC9104</span>, <time datetime="2021-08" class="refDate">August 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9104">https://www.rfc-editor.org/info/rfc9104</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="I-D.ietf-idr-bgp-model">[IDR-BGP-MODEL]</dt>
        <dd>
<span class="refAuthor">Jethanandani, M.</span>, <span class="refAuthor">Patel, K.</span>, <span class="refAuthor">Hares, S.</span>, and <span class="refAuthor">J. Haas</span>, <span class="refTitle">"BGP YANG Model for Service Provider Networks"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-idr-bgp-model-14</span>, <time datetime="2022-07-03" class="refDate">3 July 2022</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-model-14">https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-model-14</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC1195">[RFC1195]</dt>
        <dd>
<span class="refAuthor">Callon, R.</span>, <span class="refTitle">"Use of OSI IS-IS for routing in TCP/IP and dual environments"</span>, <span class="seriesInfo">RFC 1195</span>, <span class="seriesInfo">DOI 10.17487/RFC1195</span>, <time datetime="1990-12" class="refDate">December 1990</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc1195">https://www.rfc-editor.org/info/rfc1195</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2328">[RFC2328]</dt>
        <dd>
<span class="refAuthor">Moy, J.</span>, <span class="refTitle">"OSPF Version 2"</span>, <span class="seriesInfo">STD 54</span>, <span class="seriesInfo">RFC 2328</span>, <span class="seriesInfo">DOI 10.17487/RFC2328</span>, <time datetime="1998-04" class="refDate">April 1998</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2328">https://www.rfc-editor.org/info/rfc2328</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3209">[RFC3209]</dt>
        <dd>
<span class="refAuthor">Awduche, D.</span>, <span class="refAuthor">Berger, L.</span>, <span class="refAuthor">Gan, D.</span>, <span class="refAuthor">Li, T.</span>, <span class="refAuthor">Srinivasan, V.</span>, and <span class="refAuthor">G. Swallow</span>, <span class="refTitle">"RSVP-TE: Extensions to RSVP for LSP Tunnels"</span>, <span class="seriesInfo">RFC 3209</span>, <span class="seriesInfo">DOI 10.17487/RFC3209</span>, <time datetime="2001-12" class="refDate">December 2001</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3209">https://www.rfc-editor.org/info/rfc3209</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4202">[RFC4202]</dt>
        <dd>
<span class="refAuthor">Kompella, K., Ed.</span> and <span class="refAuthor">Y. Rekhter, Ed.</span>, <span class="refTitle">"Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)"</span>, <span class="seriesInfo">RFC 4202</span>, <span class="seriesInfo">DOI 10.17487/RFC4202</span>, <time datetime="2005-10" class="refDate">October 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4202">https://www.rfc-editor.org/info/rfc4202</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5286">[RFC5286]</dt>
        <dd>
<span class="refAuthor">Atlas, A., Ed.</span> and <span class="refAuthor">A. Zinin, Ed.</span>, <span class="refTitle">"Basic Specification for IP Fast Reroute: Loop-Free Alternates"</span>, <span class="seriesInfo">RFC 5286</span>, <span class="seriesInfo">DOI 10.17487/RFC5286</span>, <time datetime="2008-09" class="refDate">September 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5286">https://www.rfc-editor.org/info/rfc5286</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5340">[RFC5340]</dt>
        <dd>
<span class="refAuthor">Coltun, R.</span>, <span class="refAuthor">Ferguson, D.</span>, <span class="refAuthor">Moy, J.</span>, and <span class="refAuthor">A. Lindem</span>, <span class="refTitle">"OSPF for IPv6"</span>, <span class="seriesInfo">RFC 5340</span>, <span class="seriesInfo">DOI 10.17487/RFC5340</span>, <time datetime="2008-07" class="refDate">July 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5340">https://www.rfc-editor.org/info/rfc5340</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8402">[RFC8402]</dt>
      <dd>
<span class="refAuthor">Filsfils, C., Ed.</span>, <span class="refAuthor">Previdi, S., Ed.</span>, <span class="refAuthor">Ginsberg, L.</span>, <span class="refAuthor">Decraene, B.</span>, <span class="refAuthor">Litkowski, S.</span>, and <span class="refAuthor">R. Shakir</span>, <span class="refTitle">"Segment Routing Architecture"</span>, <span class="seriesInfo">RFC 8402</span>, <span class="seriesInfo">DOI 10.17487/RFC8402</span>, <time datetime="2018-07" class="refDate">July 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8402">https://www.rfc-editor.org/info/rfc8402</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="ACK">
<section id="appendix-A">
      <h2 id="name-acknowledgements">
<a href="#name-acknowledgements" class="section-name selfRef">Acknowledgements</a>
      </h2>
<p id="appendix-A-1">The authors would like to thank <span class="contact-name">Les Ginsberg</span>, <span class="contact-name">Baalajee S.</span>, <span class="contact-name">Amalesh       Maity</span>, <span class="contact-name">Acee Lindem</span>, <span class="contact-name">Keyur Patel</span>, <span class="contact-name">Paul Wouters</span>, <span class="contact-name">Rudy Selderslaghs</span>, <span class="contact-name">Kristy       Paine</span>, and <span class="contact-name">Shraddha Hegde</span> for their review and feedback on this
      document. The authors would like to thank <span class="contact-name">Alvaro Retana</span> for his very
      detailed AD review and comments that improved this document. The authors
      would also like to thank <span class="contact-name">John Scudder</span> for his detailed review and
      feedback on clarifying the procedures along with the example in <a href="#PROCEDURES" class="xref">Section 4</a>.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="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">Ketan Talaulikar (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Arrcus Inc.</span></div>
<div dir="auto" class="left"><span class="country-name">India</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ketant.ietf@gmail.com" class="email">ketant.ietf@gmail.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Peter Psenak</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems</span></div>
<div dir="auto" class="left"><span class="country-name">Slovakia</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ppsenak@cisco.com" class="email">ppsenak@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Jeff Tantsura</span></div>
<div dir="auto" class="left"><span class="org">Microsoft</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:jefftant.ietf@gmail.com" class="email">jefftant.ietf@gmail.com</a>
</div>
</address>
</section>
</div>
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