File: rfc7911.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 7911: Advertisement of Multiple Paths in BGP</title>
<meta content="Daniel Walton" name="author">
<meta content="Alvaro Retana" name="author">
<meta content="Enke Chen" name="author">
<meta content="John Scudder" name="author">
<meta content="
       This document defines a BGP extension that allows the advertisement
      of multiple paths for the same address prefix without the new paths
      implicitly replacing any previous ones. The essence of the extension is
      that each path is identified by a Path Identifier in addition to the
      address prefix. 
    " name="description">
<meta content="xml2rfc 3.22.0" name="generator">
<meta content="7911" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.22.0
    Python 3.12.4
    ConfigArgParse 1.7
    google-i18n-address 3.1.0
    intervaltree 3.1.0
    Jinja2 3.1.4
    lxml 4.9.4
    platformdirs 4.2.2
    pycountry 24.6.1
    pydyf 0.10.0
    PyYAML 6.0.2
    requests 2.32.3
    setuptools 72.2.0
    wcwidth 0.2.13
    weasyprint 61.2
-->
<link href="tests/input/rfc7911.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 necessary 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 */

:root {
  --font-sans: 'Noto Sans', Arial, Helvetica, sans-serif;
  --font-serif: 'Noto Serif', 'Times', 'Times New Roman', serif;
  --font-mono: 'Roboto Mono', Courier, 'Courier New', monospace;
}

@viewport {
  zoom: 1.0;
}
@-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: var(--font-sans);
  line-height: 1.6;
  scroll-behavior: smooth;
  overflow-wrap: break-word;
}
.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;
}
svg[font-family~="serif" i], svg [font-family~="serif" i] {
  font-family: var(--font-serif);
}
svg[font-family~="sans-serif" i], svg [font-family~="sans-serif" i] {
  font-family: var(--font-sans);
}
svg[font-family~="monospace" i], svg [font-family~="monospace" i] {
  font-family: var(--font-mono);
}
.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 {
  display: table;
  border: none;
  margin: 0 auto;
}

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

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

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

/* Figures */
tt, code, pre {
  background-color: #f9f9f9;
  font-family: var(--font-mono);
}
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;
}
blockquote > *:last-child {
  margin-bottom: 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}
.xref {
  overflow-wrap: normal;
}

/* 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;
}
/* Fix PDF info block run off issue */
@media print {
  #identifiers dd {
    float: none;
  }
}
#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;
}

.refSubseries {
  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: var(--font-sans);
  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;
  }
  .breakable pre {
    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 {
  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 following 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 {
  font-size: 95%;
}

/* Fix the height/width aspect for ascii art*/
.sourcecode pre,
.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 information 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;
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<table class="ears">
<thead><tr>
<td class="left">RFC 7911</td>
<td class="center">ADD-PATH</td>
<td class="right">July 2016</td>
</tr></thead>
<tfoot><tr>
<td class="left">Walton, 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/rfc7911" class="eref">7911</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="2016-07" class="published">July 2016</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">D. Walton</div>
<div class="org">Cumulus Networks</div>
</div>
<div class="author">
      <div class="author-name">A. Retana</div>
<div class="org">Cisco Systems, Inc.</div>
</div>
<div class="author">
      <div class="author-name">E. Chen</div>
<div class="org">Cisco Systems, Inc.</div>
</div>
<div class="author">
      <div class="author-name">J. Scudder</div>
<div class="org">Juniper Networks</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 7911</h1>
<h1 id="title">Advertisement of Multiple Paths in BGP</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document defines a BGP extension that allows the advertisement
      of multiple paths for the same address prefix without the new paths
      implicitly replacing any previous ones. The essence of the extension is
      that each path is identified by a Path Identifier in addition to the
      address prefix.<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
            <span><a href="http://www.rfc-editor.org/info/rfc7911">http://www.rfc-editor.org/info/rfc7911</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2016 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="http://trustee.ietf.org/license-info">http://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="auto internal xref">1</a>.  <a href="#name-introduction" class="internal 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="auto internal xref">1.1</a>.  <a href="#name-specification-of-requiremen" class="internal xref">Specification of Requirements</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="auto internal xref">2</a>.  <a href="#name-how-to-identify-a-path" class="internal xref">How to Identify a Path</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="auto internal xref">3</a>.  <a href="#name-extended-nlri-encodings" class="internal xref">Extended NLRI Encodings</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="auto internal xref">4</a>.  <a href="#name-add-path-capability" class="internal xref">ADD-PATH Capability</a></p>
</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="auto internal xref">5</a>.  <a href="#name-operation" class="internal xref">Operation</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="auto internal xref">6</a>.  <a href="#name-deployment-considerations" class="internal xref">Deployment 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="auto internal xref">7</a>.  <a href="#name-iana-considerations" class="internal xref">IANA 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="auto internal xref">8</a>.  <a href="#name-security-considerations" class="internal 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="auto internal xref">9</a>.  <a href="#name-references" class="internal 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="auto internal xref">9.1</a>.  <a href="#name-normative-references" class="internal 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="auto internal xref">9.2</a>.  <a href="#name-informative-references" class="internal 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="auto internal xref"></a><a href="#name-acknowledgments" class="internal xref">Acknowledgments</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="auto internal xref"></a><a href="#name-authors-addresses" class="internal xref">Authors' Addresses</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<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 BGP specification <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> defines an Update-Send Process to advertise the
      routes chosen by the Decision Process to other BGP speakers. No
      provisions are made to allow the advertisement of multiple paths for the
      same address prefix or Network Layer Reachability Information (NLRI).
      In fact, a route with the same NLRI as a previously advertised route
      implicitly replaces the previous advertisement.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">This document defines a BGP extension that allows the advertisement
      of multiple paths for the same address prefix without the new paths
      implicitly replacing any previous ones. The essence of the extension is
      that each path is identified by a Path Identifier in addition to the
      address prefix.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">The availability of the additional paths can help reduce or eliminate
      persistent route oscillations <span>[<a href="#RFC3345" class="cite xref">RFC3345</a>]</span>.  It can also help with optimal routing and routing 
      convergence in a network by providing potential alternate or backup paths, 
      respectively.<a href="#section-1-3" class="pilcrow">¶</a></p>
<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 "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
        "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
        document are to be interpreted as described in <span>[<a href="#RFC2119" class="cite xref">RFC2119</a>]</span>.<a href="#section-1.1-1" class="pilcrow">¶</a></p>
</section>
</section>
<section id="section-2">
      <h2 id="name-how-to-identify-a-path">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-how-to-identify-a-path" class="section-name selfRef">How to Identify a Path</a>
      </h2>
<p id="section-2-1">As defined in <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span>, a path refers to the information reported in the
      Path Attribute field of an UPDATE message. As the procedures specified
      in <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> allow only
      the advertisement of one path for a particular address prefix, a path
      for an address prefix from a BGP peer can be keyed on the address
      prefix.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">In order for a BGP speaker to advertise multiple paths for the same
      address prefix, a new identifier (termed "Path Identifier" hereafter)
      needs to be introduced so that a particular path for an address prefix
      can be identified by the combination of the address prefix and the Path
      Identifier.<a href="#section-2-2" class="pilcrow">¶</a></p>
<p id="section-2-3">The assignment of the Path Identifier for a path by a BGP speaker is
      purely a local matter. However, the Path Identifier MUST be assigned in
      such a way that the BGP speaker is able to use the (Prefix, Path
      Identifier) to uniquely identify a path advertised to a neighbor. A BGP
      speaker that re-advertises a route MUST generate its own Path Identifier
      to be associated with the re-advertised route. A BGP speaker that
      receives a route should not assume that the identifier carries any
      particular semantics.<a href="#section-2-3" class="pilcrow">¶</a></p>
</section>
<div id="code">
<section id="section-3">
      <h2 id="name-extended-nlri-encodings">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-extended-nlri-encodings" class="section-name selfRef">Extended NLRI Encodings</a>
      </h2>
<p id="section-3-1">In order to carry the Path Identifier in an UPDATE message, the NLRI
      encoding MUST be extended by prepending the Path Identifier field, which
      is of four octets.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">For example, the NLRI encoding specified in <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> is extended as the following:<a href="#section-3-2" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-3-3">
<pre>
               +--------------------------------+
               | Path Identifier (4 octets)     |
               +--------------------------------+
               | Length (1 octet)               |
               +--------------------------------+
               | Prefix (variable)              |
               +--------------------------------+</pre><a href="#section-3-3" class="pilcrow">¶</a>
</div>
<p id="section-3-4">The usage of the extended NLRI encodings is specified in <a href="#ops" class="auto internal xref">Section 5</a>.<a href="#section-3-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="capa">
<section id="section-4">
      <h2 id="name-add-path-capability">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-add-path-capability" class="section-name selfRef">ADD-PATH Capability</a>
      </h2>
<p id="section-4-1">The ADD-PATH Capability is a BGP capability <span>[<a href="#RFC5492" class="cite xref">RFC5492</a>]</span>, with Capability Code
      69. The Capability Length field of this capability is
      variable. The Capability Value field consists of one or more of the
      following tuples:<a href="#section-4-1" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-4-2">
<pre>
             +------------------------------------------------+
             | Address Family Identifier (2 octets)           |
             +------------------------------------------------+
             | Subsequent Address Family Identifier (1 octet) |
             +------------------------------------------------+
             | Send/Receive (1 octet)                         |
             +------------------------------------------------+</pre><a href="#section-4-2" class="pilcrow">¶</a>
</div>
<p id="section-4-3">The meaning and use of the fields are as follows:<a href="#section-4-3" class="pilcrow">¶</a></p>
<ul class="normal ulEmpty">
<li class="normal ulEmpty" id="section-4-4.1">
          <p id="section-4-4.1.1">Address Family Identifier (AFI):<a href="#section-4-4.1.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4-4.1.2.1">
              <p id="section-4-4.1.2.1.1">This field is the same as the one used in <span>[<a href="#RFC4760" class="cite xref">RFC4760</a>]</span>.<a href="#section-4-4.1.2.1.1" class="pilcrow">¶</a></p>
</li>
          </ul>
</li>
        <li class="normal ulEmpty" id="section-4-4.2">
          <p id="section-4-4.2.1">Subsequent Address Family Identifier (SAFI):<a href="#section-4-4.2.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4-4.2.2.1">
              <p id="section-4-4.2.2.1.1">This field is the same as the one used in <span>[<a href="#RFC4760" class="cite xref">RFC4760</a>]</span>.<a href="#section-4-4.2.2.1.1" class="pilcrow">¶</a></p>
</li>
          </ul>
</li>
        <li class="normal ulEmpty" id="section-4-4.3">
          <p id="section-4-4.3.1">Send/Receive:<a href="#section-4-4.3.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4-4.3.2.1">
              <p id="section-4-4.3.2.1.1">This field indicates whether the sender is (a) able to
              receive multiple paths from its peer (value 1), (b) able to send
              multiple paths to its peer (value 2), or (c) both (value 3) for
              the &lt;AFI, SAFI&gt;.<a href="#section-4-4.3.2.1.1" class="pilcrow">¶</a></p>
</li>
            <li class="normal" id="section-4-4.3.2.2">
              <p id="section-4-4.3.2.2.1">If any other value is received, then the capability SHOULD be
              treated as not understood and ignored <span>[<a href="#RFC5492" class="cite xref">RFC5492</a>]</span>.<a href="#section-4-4.3.2.2.1" class="pilcrow">¶</a></p>
</li>
          </ul>
</li>
      </ul>
<p id="section-4-5">A BGP speaker that wishes to indicate support for multiple
      AFI/SAFIs MUST do so by including the information in a single instance of
      the ADD-PATH Capability.<a href="#section-4-5" class="pilcrow">¶</a></p>
</section>
</div>
<div id="ops">
<section id="section-5">
      <h2 id="name-operation">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-operation" class="section-name selfRef">Operation</a>
      </h2>
<p id="section-5-1">The Path Identifier specified in <a href="#code" class="auto internal xref">Section 3</a> can be used to
      advertise multiple paths for the same address prefix without subsequent
      advertisements replacing the previous ones. Apart from the fact that
      this is now possible, the route advertisement rules of <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> are not changed. In
      particular, a new advertisement for a given address prefix and a given
      Path Identifier replaces a previous advertisement for the same address
      prefix and Path Identifier. If a BGP speaker receives a message to
      withdraw a prefix with a Path Identifier not seen before, it SHOULD
      silently ignore it.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">For a BGP speaker to be able to send multiple paths to its peer, that
      BGP speaker MUST advertise the ADD-PATH Capability with the Send/Receive
      field set to either 2 or 3, and MUST receive from its peer the ADD-PATH
      Capability with the Send/Receive field set to either 1 or 3, for the
      corresponding &lt;AFI, SAFI&gt;.<a href="#section-5-2" class="pilcrow">¶</a></p>
<p id="section-5-3">A BGP speaker MUST follow the procedures defined in <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> when generating an
      UPDATE message for a particular &lt;AFI, SAFI&gt; to a peer unless the
      BGP speaker advertises the ADD-PATH Capability to the peer indicating
      its ability to send multiple paths for the &lt;AFI, SAFI&gt;, and also
      receives the ADD-PATH Capability from the peer indicating its ability to
      receive multiple paths for the &lt;AFI, SAFI&gt;, in which case the
      speaker MUST generate a route update for the &lt;AFI, SAFI&gt; based on
      the combination of the address prefix and the Path Identifier, and use
      the extended NLRI encodings specified in this document. The peer SHALL
      act accordingly in processing an UPDATE message related to a particular
      &lt;AFI, SAFI&gt;.<a href="#section-5-3" class="pilcrow">¶</a></p>
<p id="section-5-4">A BGP speaker SHOULD include the best route <span>[<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> when more than one path is
      advertised to a neighbor, unless it is a path received from
      that neighbor.<a href="#section-5-4" class="pilcrow">¶</a></p>
<p id="section-5-5">As the Path Identifiers are locally assigned, and may or may not be
      persistent across a control plane restart of a BGP speaker, an
      implementation SHOULD take special care so that the underlying
      forwarding plane of a "Receiving Speaker" as described in <span>[<a href="#RFC4724" class="cite xref">RFC4724</a>]</span> is not affected
      during the graceful restart of a BGP session.<a href="#section-5-5" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-6">
      <h2 id="name-deployment-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-deployment-considerations" class="section-name selfRef">Deployment Considerations</a>
      </h2>
<p id="section-6-1">The extension proposed in this document provides a mechanism for a
      BGP speaker to advertise multiple paths over a BGP session. Care needs
      to be taken in its deployment to ensure consistent routing and
      forwarding in a network <span>[<a href="#ADDPATH" class="cite xref">ADDPATH</a>]</span>.<a href="#section-6-1" class="pilcrow">¶</a></p>
<p id="section-6-2">The only explicit indication that the encoding described in <a href="#code" class="auto internal xref">Section 3</a>
      is in use in a particular BGP session is the exchange of Capabilities
      described in <a href="#capa" class="auto internal xref">Section 4</a>.  If the exchange is successful <span>[<a href="#RFC5492" class="cite xref">RFC5492</a>]</span>, then the BGP speakers
      will be able to process all BGP UPDATES properly, as described in <a href="#ops" class="auto internal xref">Section 5</a>.
      However, if, for example, a packet analyzer is used on the wire to examine 
      an active BGP session, it may not be able to properly decode the BGP UPDATES
      because it lacks prior knowledge of the exchanged Capabilities.<a href="#section-6-2" class="pilcrow">¶</a></p>
<p id="section-6-3">When deployed as a provider edge router or a peering router that
      interacts with external neighbors, a BGP speaker usually advertises at
      most one path to the internal neighbors in a network. In the case where the
      speaker is configured to advertise multiple paths to the internal
      neighbors, and additional information is needed for the application, the
      speaker could use attributes such as the Edge_Discriminator attribute
      <span>[<a href="#FAST" class="cite xref">FAST</a>]</span>. The use of that type of
      additional information is outside the scope of this document.<a href="#section-6-3" class="pilcrow">¶</a></p>
</section>
<section id="section-7">
      <h2 id="name-iana-considerations">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-7-1">IANA has assigned the value 69 for the ADD-PATH Capability
      described in this document. This registration is in the "Capability
      Codes" registry.<a href="#section-7-1" class="pilcrow">¶</a></p>
</section>
<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">This document defines a BGP extension that allows the advertisement
      of multiple paths for the same address prefix without the new paths
      implicitly replacing any previous ones. As a result, multiple paths for
      a large number of prefixes may be received by a BGP speaker, potentially
      depleting memory resources or even causing network-wide instability, which
      can be considered a denial-of-service attack.  Note that this is not a new
      vulnerability, but one that is present in the base BGP specification <span>[<a href="#RFC4272" class="cite xref">RFC4272</a>]</span>.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">
  The use of the ADD-PATH Capability is intended to address specific
  needs related to, for example, <span><a href="#STOP-OSC" class="internal xref">eliminating route oscillations that
  were induced by the MULTI_EXIT_DISC (MED) attribute</a> [<a href="#STOP-OSC" class="cite xref">STOP-OSC</a>]</span>.

  While describing the applications for the
      ADD-PATH Capability is outside the scope of this document, users
      are encouraged to examine their behavior and potential impact by
      studying the best practices described in <span>[<a href="#ADDPATH" class="cite xref">ADDPATH</a>]</span>.<a href="#section-8-2" class="pilcrow">¶</a></p>
<p id="section-8-3">Security concerns in the base operation of <span><a href="#RFC4271" class="internal xref">BGP</a> [<a href="#RFC4271" class="cite xref">RFC4271</a>]</span> also apply.<a href="#section-8-3" class="pilcrow">¶</a></p>
</section>
<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="RFC4271">[RFC4271]</dt>
        <dd>
<span class="refAuthor">Rekhter, Y., Ed.</span>, <span class="refAuthor">Li, T., Ed.</span>, and <span class="refAuthor">S. Hares, Ed.</span>, <span class="refTitle">"A Border Gateway Protocol 4 (BGP-4)"</span>, <span class="seriesInfo">RFC 4271</span>, <span class="seriesInfo">DOI 10.17487/RFC4271</span>, <time datetime="2006-01" class="refDate">January 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4271">https://www.rfc-editor.org/info/rfc4271</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4760">[RFC4760]</dt>
        <dd>
<span class="refAuthor">Bates, T.</span>, <span class="refAuthor">Chandra, R.</span>, <span class="refAuthor">Katz, D.</span>, and <span class="refAuthor">Y. Rekhter</span>, <span class="refTitle">"Multiprotocol Extensions for BGP-4"</span>, <span class="seriesInfo">RFC 4760</span>, <span class="seriesInfo">DOI 10.17487/RFC4760</span>, <time datetime="2007-01" class="refDate">January 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4760">https://www.rfc-editor.org/info/rfc4760</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5492">[RFC5492]</dt>
      <dd>
<span class="refAuthor">Scudder, J.</span> and <span class="refAuthor">R. Chandra</span>, <span class="refTitle">"Capabilities Advertisement with BGP-4"</span>, <span class="seriesInfo">RFC 5492</span>, <span class="seriesInfo">DOI 10.17487/RFC5492</span>, <time datetime="2009-02" class="refDate">February 2009</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5492">https://www.rfc-editor.org/info/rfc5492</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="ADDPATH">[ADDPATH]</dt>
        <dd>
<span class="refAuthor">Uttaro, J.</span>, <span class="refAuthor">Francois, P.</span>, <span class="refAuthor">Patel, K.</span>, <span class="refAuthor">Haas, J.</span>, <span class="refAuthor">Simpson, A.</span>, and <span class="refAuthor">R. Fragassi</span>, <span class="refTitle">"Best Practices for Advertisement of Multiple Paths in IBGP"</span>, <span class="seriesInfo">Work in Progress, draft-ietf-idr-add-paths-guidelines-08</span>, <time datetime="2016-04-25" class="refDate">25 April 2016</time>. </dd>
<dd class="break"></dd>
<dt id="FAST">[FAST]</dt>
        <dd>
<span class="refAuthor">Mohapatra, P.</span>, <span class="refAuthor">Fernando, R.</span>, <span class="refAuthor">Filsfils, C.</span>, and <span class="refAuthor">R. Raszuk</span>, <span class="refTitle">"Fast Connectivity Restoration Using BGP Add-path"</span>, <span class="seriesInfo">Work in Progress, draft-pmohapat-idr-fast-conn-restore-03</span>, <time datetime="2013-01-22" class="refDate">22 January 2013</time>. </dd>
<dd class="break"></dd>
<dt id="RFC3345">[RFC3345]</dt>
        <dd>
<span class="refAuthor">McPherson, D.</span>, <span class="refAuthor">Gill, V.</span>, <span class="refAuthor">Walton, D.</span>, and <span class="refAuthor">A. Retana</span>, <span class="refTitle">"Border Gateway Protocol (BGP) Persistent Route Oscillation Condition"</span>, <span class="seriesInfo">RFC 3345</span>, <span class="seriesInfo">DOI 10.17487/RFC3345</span>, <time datetime="2002-08" class="refDate">August 2002</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3345">https://www.rfc-editor.org/info/rfc3345</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4272">[RFC4272]</dt>
        <dd>
<span class="refAuthor">Murphy, S.</span>, <span class="refTitle">"BGP Security Vulnerabilities Analysis"</span>, <span class="seriesInfo">RFC 4272</span>, <span class="seriesInfo">DOI 10.17487/RFC4272</span>, <time datetime="2006-01" class="refDate">January 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4272">https://www.rfc-editor.org/info/rfc4272</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4724">[RFC4724]</dt>
        <dd>
<span class="refAuthor">Sangli, S.</span>, <span class="refAuthor">Chen, E.</span>, <span class="refAuthor">Fernando, R.</span>, <span class="refAuthor">Scudder, J.</span>, and <span class="refAuthor">Y. Rekhter</span>, <span class="refTitle">"Graceful Restart Mechanism for BGP"</span>, <span class="seriesInfo">RFC 4724</span>, <span class="seriesInfo">DOI 10.17487/RFC4724</span>, <time datetime="2007-01" class="refDate">January 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4724">https://www.rfc-editor.org/info/rfc4724</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="STOP-OSC">[STOP-OSC]</dt>
      <dd>
<span class="refAuthor">Walton, D.</span>, <span class="refAuthor">Retana, A.</span>, <span class="refAuthor">Chen, E.</span>, and <span class="refAuthor">J. Scudder</span>, <span class="refTitle">"BGP Persistent Route Oscillation Solutions"</span>, <span class="seriesInfo">Work in Progress, draft-ietf-idr-route-oscillation-stop-03</span>, <time datetime="2016-04-30" class="refDate">30 April 2016</time>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<section id="appendix-A">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="appendix-A-1">We would like to thank David Cook and Naiming Shen for their
      contributions to the design and development of the extension.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
<p id="appendix-A-2">Many people have made valuable comments and suggestions, including
      Rex Fernando, Eugene Kim, Danny McPherson, Dave Meyer, Pradosh
      Mohapatra, Keyur Patel, Robert Raszuk, Eric Rosen, Srihari Sangli, Dan
      Tappan, Mark Turner, Jeff Haas, Jay Borkenhagen, Mach Chen, Denis Ovsienko,
      Carlos Pignataro, Meral Shirazipour, and Kathleen Moriarty.<a href="#appendix-A-2" class="pilcrow">¶</a></p>
</section>
<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">Daniel Walton</span></div>
<div dir="auto" class="left"><span class="org">Cumulus Networks</span></div>
<div dir="auto" class="left"><span class="street-address">185 E. Dana Street</span></div>
<div dir="auto" class="left">
<span class="locality">Mountain View</span>, <span class="region">CA</span> <span class="postal-code">94041</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:dwalton@cumulusnetworks.com" class="email">dwalton@cumulusnetworks.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Alvaro Retana</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">Kit Creek Rd.</span></div>
<div dir="auto" class="left">
<span class="locality">Research Triangle Park</span>, <span class="region">NC</span> <span class="postal-code">27709</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:aretana@cisco.com" class="email">aretana@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Enke Chen</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">170 W. Tasman Dr.</span></div>
<div dir="auto" class="left">
<span class="locality">San Jose</span>, <span class="region">CA</span> <span class="postal-code">95134</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:enkechen@cisco.com" class="email">enkechen@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">John Scudder</span></div>
<div dir="auto" class="left"><span class="org">Juniper Networks</span></div>
<div dir="auto" class="left"><span class="street-address">1194 N. Mathilda Ave</span></div>
<div dir="auto" class="left">
<span class="locality">Sunnyvale</span>, <span class="region">CA</span> <span class="postal-code">94089</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:jgs@juniper.net" class="email">jgs@juniper.net</a>
</div>
</address>
</section>
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