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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 9081: Interoperation between Multicast Virtual Private Network (MVPN) and Multicast Source Directory Protocol (MSDP) Source-Active Routes</title>
<meta content="Zhaohui Zhang" name="author">
<meta content="Lenny Giuliano" name="author">
<meta content="
       This document specifies the procedures for interoperation between
         Multicast Virtual Private Network (MVPN) Source-Active (SA) routes and
       customer Multicast Source Discovery Protocol (MSDP) SA routes,
         which is useful for MVPN provider networks offering services to
         customers with an existing MSDP infrastructure. 
  Without the procedures
         described in this document, VPN-specific MSDP sessions are required
         among the Provider Edge (PE) routers that are customer MSDP peers. This
  document updates RFC 6514.
       
    " name="description">
<meta content="xml2rfc 3.9.1" name="generator">
<meta content="9081" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.9.1
    Python 3.6.10
    appdirs 1.4.4
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    WeasyPrint 51
-->
<link href="rfc9081.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 {
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  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 {
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}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
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  font-weight: bold;
  line-height: 1.3;
}
#title {
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svg {
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/* definition lists */
dl {
}
dl > dt {
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/* 
dl.nohang > dt {
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}
*/
dl > dd {
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dl > dd > dl {
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/* links */
a {
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a[href] {
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}
a[href]:hover {
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figcaption a[href],
a[href].selfRef {
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/* XXX probably not this:
a.selfRef:hover {
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} */

/* Figures */
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/* aside, blockquote */
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cite {
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/* tables */
table {
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/* pilcrow */
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.role {
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#identifiers .authors .author {
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#identifiers .authors .org {
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/* The prepared/rendered info at the very bottom of the page */
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}
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/* table of contents */
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nav.toc ul {
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}
nav.toc li {
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}
/* references */
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}
.references dd {
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.refInstance {
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.references .ascii {
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}

/* index */
.index ul {
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}
.index ul ul {
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}
.index li {
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.indexIndex {
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.index a {
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}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
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/* authors */
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address.vcard .nameRole {
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address.vcard .label {
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address.vcard .type {
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.alternative-contact {
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hr.addr {
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/* temporary notes */
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  padding: 0.2em;
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  color: #9e2a00; /* Arlen: WCAG 2019 */
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}
.rfcEditorRemove {
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  background-color: #ffd; /* Arlen: WCAG 2019 */
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.cref {
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.crefSource {
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}
/* alternative layout for smaller screens */
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    padding-top: 2em;
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  #title {
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  h1 {
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  #toc {
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  #toc h2 {
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    padding: 4px 0 4px 6px;
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  #toc h2::before { /* css hamburger */
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}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
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    padding-right: 29em;
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  #toc {
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    right: 42px;
    width: 25%;
    margin: 0;
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  img { /* future proofing */
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}

/* pagination */
@media print {
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  #toc {
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}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
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.ears thead .center {
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.ears tfoot .right {
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*/

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@page {
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  @top-left {
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    vertical-align: bottom;
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}

/* 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 */
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/* Leave room in document info to show Internet-Draft on one line */
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/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
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/* 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,
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  #toc h2 a:hover,
  #toc a.toplink,
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    background-color: #444;
    text-decoration: none;
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}

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

/* Style section numbers with more space between number and title */
.section-number {
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/* prevent monospace from becoming overly large */
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/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
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}


/* 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 {
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}
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
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table {
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}

/* 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 {
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}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* Make pilcrows on dd visible */
@media screen {
  dd:hover > a.pilcrow {
    visibility: visible;
  }
}
/* Make the placement of figcaption match that of a table's caption
   by removing the figure's added bottom margin */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
   margin-bottom: 0;
}
.alignLeft,
.alignCenter,
.alignRight {
  margin: 1em 0 0 0;
}
/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
   possibly even requiring a new line */
@media print {
  a.pilcrow {
    display: none;
  }
}
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<table class="ears">
<thead><tr>
<td class="left">RFC 9081</td>
<td class="center">MVPN and MSDP SA Interoperation</td>
<td class="right">July 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Zhang &amp; Giuliano</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/rfc9081" class="eref">9081</a></dd>
<dt class="label-updates">Updates:</dt>
<dd class="updates">
<a href="https://www.rfc-editor.org/rfc/rfc6514" class="eref">6514</a> </dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2021-07" class="published">July 2021</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">Z. Zhang</div>
<div class="org">Juniper Networks</div>
</div>
<div class="author">
      <div class="author-name">L. Giuliano</div>
<div class="org">Juniper Networks</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9081</h1>
<h1 id="title">Interoperation between Multicast Virtual Private Network (MVPN) and Multicast Source Directory Protocol (MSDP) Source-Active Routes</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document specifies the procedures for interoperation between
         Multicast Virtual Private Network (MVPN) Source-Active (SA) routes and
       customer Multicast Source Discovery Protocol (MSDP) SA routes,
         which is useful for MVPN provider networks offering services to
         customers with an existing MSDP infrastructure. 
  Without the procedures
         described in this document, VPN-specific MSDP sessions are required
         among the Provider Edge (PE) routers that are customer MSDP peers. This
  document updates RFC 6514.<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="https://www.rfc-editor.org/info/rfc9081">https://www.rfc-editor.org/info/rfc9081</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2021 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Simplified BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Simplified BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="compact ulEmpty ulBare toc">
<li class="compact ulEmpty ulBare toc" 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="ulBare toc compact ulEmpty">
<li class="ulBare toc compact 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-mvpn-rpt-spt-mode" class="xref">MVPN RPT-SPT Mode</a></p>
</li>
            </ul>
</li>
          <li class="compact ulEmpty ulBare toc" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1"><a href="#section-2" class="xref">2</a>.  <a href="#name-terminology" class="xref">Terminology</a></p>
<ul class="ulBare toc compact ulEmpty">
<li class="ulBare toc compact ulEmpty" id="section-toc.1-1.2.2.1">
                <p id="section-toc.1-1.2.2.1.1" class="keepWithNext"><a href="#section-2.1" class="xref">2.1</a>.  <a href="#name-requirements-language" class="xref">Requirements Language</a></p>
</li>
            </ul>
</li>
          <li class="compact ulEmpty ulBare toc" 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-specification" class="xref">Specification</a></p>
</li>
          <li class="compact ulEmpty ulBare toc" 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-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="compact ulEmpty ulBare toc" 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-iana-considerations" class="xref">IANA Considerations</a></p>
</li>
          <li class="compact ulEmpty ulBare toc" 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-references" class="xref">References</a></p>
<ul class="ulBare toc compact ulEmpty">
<li class="ulBare toc compact ulEmpty" id="section-toc.1-1.6.2.1">
                <p id="section-toc.1-1.6.2.1.1"><a href="#section-6.1" class="xref">6.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="ulBare toc compact ulEmpty" id="section-toc.1-1.6.2.2">
                <p id="section-toc.1-1.6.2.2.1"><a href="#section-6.2" class="xref">6.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="compact ulEmpty ulBare toc" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#appendix-A" class="xref"></a><a href="#name-acknowledgements" class="xref">Acknowledgements</a></p>
</li>
          <li class="compact ulEmpty ulBare toc" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#appendix-B" class="xref"></a><a href="#name-authors-addresses" class="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">Section <span><a href="https://www.rfc-editor.org/rfc/rfc6514#section-14" class="relref">14</a> (<a href="https://www.rfc-editor.org/rfc/rfc6514#section-14" class="relref"> "Supporting 
      PIM-SM without Inter-Site Shared C-Trees"</a>)</span> of
       <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> specifies the procedures for MVPN PEs to discover (C-S,C-G)
       via MVPN Source-Active A-D routes and then send Source Tree Join (C-S,C-G) C-multicast
       routes towards the ingress PEs to establish shortest path trees (SPTs) for customer Any-Source Multicast (ASM) flows
       for which they have downstream receivers.
       (C-*,C-G) C-multicast routes are not sent among the PEs, so inter-site
       shared C-Trees are not used, and the method is generally referred to as
       "spt-only" mode.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">With this mode, the MVPN Source-Active routes are functionally similar to
       MSDP Source-Active messages. For a VPN,
    one or more of the PEs, say PE1,
       either acts as a C-RP and learns of (C-S,C-G) via PIM Register messages
       or has MSDP sessions with some MSDP peers and learns of (C-S,C-G) via
       MSDP SA messages. In either case, PE1 will then originate MVPN SA
       routes for other PEs to learn (C-S,C-G).<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3"><span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> only specifies that a PE receiving the MVPN SA routes,
       say PE2,  will advertise Source Tree Join (C-S,C-G) C-multicast routes if it has
       corresponding (C-*,C-G) state learnt from its Customer Edge (CE). PE2 may also have MSDP
       sessions for the VPN with other C-RPs at its site, but
       <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> does not specify that PE2 advertises MSDP SA messages to those
       MSDP peers for the (C-S,C-G) that it learns via MVPN SA routes. 
       PE2 would need to have an MSDP session with PE1 (that advertised the
       MVPN SA messages) to learn the sources via MSDP SA messages for it to
       advertise the MSDP SA to its local peers. To make things worse, unless
       blocked by policy control, PE2 would in turn advertise MVPN SA routes
       because of those MSDP SA messages that it receives from PE1, which are
       redundant and unnecessary. Also notice that the PE1-PE2 MSDP
       session is VPN specific (i.e., only for a single VPN),
    while the BGP sessions over which the MVPN
       routes are advertised are not.<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">If a PE does advertise MSDP SA messages based on received  MVPN SA
       routes, the VPN-specific MSDP sessions with other PEs are no longer needed.
       Additionally, this MVPN/MSDP SA interoperation has the following
       inherent benefits for a BGP-based solution.<a href="#section-1-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-1-5.1">MSDP SA refreshes are replaced with BGP hard state.<a href="#section-1-5.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-1-5.2">Route reflectors can be used instead of having peer-to-peer sessions.<a href="#section-1-5.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-1-5.3">VPN extranet <span>[<a href="#RFC2764" class="xref">RFC2764</a>]</span> mechanisms can be used to propagate (C-S,C-G)
             information across VPNs with flexible policy control.<a href="#section-1-5.3" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-1-6">While MSDP Source-Active routes contain the 
source, group, and RP addresses of a given multicast flow, MVPN Source-Active 
routes only contain the source and group.  MSDP requires the RP address 
information in order to perform MSDP peer Reverse Path Forwarding (RPF).  Therefore, this document 
describes how to convey the RP address information into the MVPN Source-Active 
route using an Extended Community so this information can be shared 
with an existing MSDP infrastructure.<a href="#section-1-6" class="pilcrow">¶</a></p>
<p id="section-1-7">The procedures apply to Global Table Multicast (GTM) <span>[<a href="#RFC7716" class="xref">RFC7716</a>]</span> as well.<a href="#section-1-7" class="pilcrow">¶</a></p>
<section id="section-1.1">
        <h3 id="name-mvpn-rpt-spt-mode">
<a href="#section-1.1" class="section-number selfRef">1.1. </a><a href="#name-mvpn-rpt-spt-mode" class="section-name selfRef">MVPN RPT-SPT Mode</a>
        </h3>
<p id="section-1.1-1">For comparison, another method of supporting customer ASM is generally
       referred to as "rpt-spt" mode. Section <span><a href="https://www.rfc-editor.org/rfc/rfc6514#section-13" class="relref">13</a> (<a href="https://www.rfc-editor.org/rfc/rfc6514#section-13" class="relref">"Switching from a Shared 
       C-Tree to a Source C-Tree"</a>)</span> of <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> specifies the MVPN SA procedures
       for that mode, but those SA routes are a replacement for PIM-ASM
       assert and (s,g,rpt) prune mechanisms, not for source discovery purposes.
       MVPN/MSDP SA interoperation for the "rpt-spt" mode is outside the scope
       of this document. In the rest of the document, the "spt-only" mode is
       assumed.<a href="#section-1.1-1" class="pilcrow">¶</a></p>
</section>
</section>
<section id="section-2">
      <h2 id="name-terminology">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-terminology" class="section-name selfRef">Terminology</a>
      </h2>
<p id="section-2-1">Familiarity with MVPN <span>[<a href="#RFC6513" class="xref">RFC6513</a>]</span> <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> and MSDP <span>[<a href="#RFC3618" class="xref">RFC3618</a>]</span> protocols and procedures is assumed.
       Some terminology is listed below for convenience.<a href="#section-2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-2-2">
        <dt id="section-2-2.1">ASM:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.2">Any-Source Multicast<a href="#section-2-2.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.3">SPT:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.4">source-specific Shortest Path Tree<a href="#section-2-2.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.5">RPT:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.6">Rendezvous Point Tree<a href="#section-2-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.7">C-S:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.8">a multicast source address, identifying a multicast source
            located at a VPN customer site<a href="#section-2-2.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.9">C-G:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.10">a multicast group address used by a VPN customer<a href="#section-2-2.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.11">C-RP:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.12">a multicast Rendezvous Point for a VPN customer<a href="#section-2-2.12" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.13">C-multicast:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.14">a multicast for a VPN customer<a href="#section-2-2.14" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.15">EC:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.16">Extended Community<a href="#section-2-2.16" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-2.17">GTM:</dt>
        <dd style="margin-left: 7.0em" id="section-2-2.18">Global Table Multicast, i.e., a multicast in the default or global
 routing table vs. a VPN Routing and Forwarding (VRF) table<a href="#section-2-2.18" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
<section id="section-2.1">
        <h3 id="name-requirements-language">
<a href="#section-2.1" class="section-number selfRef">2.1. </a><a href="#name-requirements-language" class="section-name selfRef">Requirements Language</a>
        </h3>
<p id="section-2.1-1"> 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-2.1-1" class="pilcrow">¶</a></p>
</section>
</section>
<section id="section-3">
      <h2 id="name-specification">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-specification" class="section-name selfRef">Specification</a>
      </h2>
<p id="section-3-1">The MVPN PEs that act as customer RPs or have one or more MSDP sessions
       in a VPN (or the global table in case of GTM) are treated as an MSDP
       mesh group for that VPN (or the global table). In the rest of the
       document, it is referred to as the PE mesh group. This PE mesh group
    <span class="bcp14">MUST NOT</span> include other MSDP speakers and is integrated
       into the rest of the MSDP infrastructure for the VPN (or the global table)
       following normal MSDP rules and practices.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">When an MVPN PE advertises an MVPN SA route following procedures in
       <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> for the "spt-only" mode,
       it <span class="bcp14">MUST</span> attach an "MVPN SA RP-address Extended Community". This
       is a Transitive IPv4-Address-Specific Extended Community. 
       The Local
       Administrator field is set to zero, and the Global Administrator field
       is set to an RP address determined as the following:<a href="#section-3-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3-3.1">If the (C-S,C-G) is learnt as a result of the PIM Register
             mechanism, the local RP address for the C-G is used.<a href="#section-3-3.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-3-3.2">If the (C-S,C-G) is learnt as a result of incoming MSDP SA messages,
             the RP address in the selected MSDP SA message is used.<a href="#section-3-3.2" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-3-4">In addition to the procedures in <span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span>, an MVPN PE may be provisioned
       to generate MSDP SA messages from received MVPN SA routes, with or
       without local policy control. If a received MVPN SA route triggers an
       MSDP SA message, the MVPN SA route is treated as if a corresponding MSDP SA message
       was received from within the PE mesh group and normal MSDP procedure
       is followed (e.g., an MSDP SA message is advertised to other MSDP peers
       outside the PE mesh group). The (S,G) information comes from the
       (C-S,C-G) encoding in the MVPN SA Network Layer Reachability Information 
       (NLRI), and the RP address comes from
       the "MVPN SA RP-address EC" mentioned above.
       If the received MVPN SA route does not have the EC (this could
       be from a legacy PE that does not have the capability to attach the EC),
       the local RP address for the C-G is used. In that case,
   it is possible that the RP inserted into the MSDP SA message for the C-G is actually the MSDP peer
   to which the generated MSDP message is advertised, causing the peer to
   discard it due to RPF failure. To get around that problem, the peer <span class="bcp14">SHOULD</span>
   use local policy to accept the MSDP SA message.<a href="#section-3-4" class="pilcrow">¶</a></p>
<p id="section-3-5">An MVPN PE <span class="bcp14">MAY</span> treat only the best MVPN SA route selected by the BGP route
       selection process (instead of all
       MVPN SA routes) for a given (C-S,C-G) as a received MSDP SA message (and
       advertise the corresponding MSDP message). In that case, if the selected
       best MVPN SA route does not have the "MVPN SA RP-address
       EC" but another route for the same (C-S, C-G) does, then the next
       best route with the EC <span class="bcp14">SHOULD</span> be chosen.  As a result, if/when the
       best MVPN SA route with the EC changes, a new MSDP SA message is 
 advertised if the RP address determined according to the newly selected
 MVPN SA route is different from before. The MSDP SA state associated with
 the previously advertised MSDP SA message with the older RP address will be timed out.<a href="#section-3-5" class="pilcrow">¶</a></p>
</section>
<div id="Security">
<section id="section-4">
      <h2 id="name-security-considerations">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-4-1">
<span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> specifies the procedure for a PE to generate an MVPN SA upon 
discovering a (C-S,C-G) flow (e.g., via a received MSDP SA message) in a VPN.
This document extends this capability in the reverse direction --
upon receiving an MVPN SA route in a VPN, generate a
corresponding MSDP SA and advertise it to MSDP peers in the same VPN.  
As such, the capabilities specified in this document introduce no 
additional security considerations beyond those already specified in 
<span>[<a href="#RFC6514" class="xref">RFC6514</a>]</span> and <span>[<a href="#RFC3618" class="xref">RFC3618</a>]</span>.  Moreover, the 
capabilities specified in this document 
actually eliminate the control message amplification that exists today 
where VPN-specific MSDP sessions are required among the PEs that are 
customer MSDP peers, which lead to redundant messages (MSDP SAs and MVPN 
SAs) being carried in parallel between PEs.<a href="#section-4-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="sarpec">
<section id="section-5">
      <h2 id="name-iana-considerations">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-5-1">
      IANA registered the following in the "Transitive IPv4-Address-Specific Extended Community Sub-Types" registry:<a href="#section-5-1" class="pilcrow">¶</a></p>
<div id="table_1">
<table class="center" id="table-1">
        <caption><a href="#table-1" class="selfRef">Table 1</a></caption>
<thead>
          <tr>
            <th class="text-left" rowspan="1" colspan="1">Value</th>
            <th class="text-left" rowspan="1" colspan="1">Description</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">0x20</td>
            <td class="text-left" rowspan="1" colspan="1">MVPN SA RP-address Extended Community</td>
          </tr>
        </tbody>
      </table>
</div>
</section>
</div>
<section id="section-6">
      <h2 id="name-references">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-6.1">
        <h3 id="name-normative-references">
<a href="#section-6.1" class="section-number selfRef">6.1. </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="RFC3618">[RFC3618]</dt>
        <dd>
<span class="refAuthor">Fenner, B., Ed.</span> and <span class="refAuthor">D. Meyer, Ed.</span>, <span class="refTitle">"Multicast Source Discovery Protocol (MSDP)"</span>, <span class="seriesInfo">RFC 3618</span>, <span class="seriesInfo">DOI 10.17487/RFC3618</span>, <time datetime="2003-10" class="refDate">October 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3618">https://www.rfc-editor.org/info/rfc3618</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6514">[RFC6514]</dt>
        <dd>
<span class="refAuthor">Aggarwal, R.</span>, <span class="refAuthor">Rosen, E.</span>, <span class="refAuthor">Morin, T.</span>, and <span class="refAuthor">Y. Rekhter</span>, <span class="refTitle">"BGP Encodings and Procedures for Multicast in MPLS/BGP IP VPNs"</span>, <span class="seriesInfo">RFC 6514</span>, <span class="seriesInfo">DOI 10.17487/RFC6514</span>, <time datetime="2012-02" class="refDate">February 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6514">https://www.rfc-editor.org/info/rfc6514</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>
</dl>
</section>
<section id="section-6.2">
        <h3 id="name-informative-references">
<a href="#section-6.2" class="section-number selfRef">6.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="RFC2764">[RFC2764]</dt>
        <dd>
<span class="refAuthor">Gleeson, B.</span>, <span class="refAuthor">Lin, A.</span>, <span class="refAuthor">Heinanen, J.</span>, <span class="refAuthor">Armitage, G.</span>, and <span class="refAuthor">A. Malis</span>, <span class="refTitle">"A Framework for IP Based Virtual Private Networks"</span>, <span class="seriesInfo">RFC 2764</span>, <span class="seriesInfo">DOI 10.17487/RFC2764</span>, <time datetime="2000-02" class="refDate">February 2000</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2764">https://www.rfc-editor.org/info/rfc2764</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6513">[RFC6513]</dt>
        <dd>
<span class="refAuthor">Rosen, E., Ed.</span> and <span class="refAuthor">R. Aggarwal, Ed.</span>, <span class="refTitle">"Multicast in MPLS/BGP IP VPNs"</span>, <span class="seriesInfo">RFC 6513</span>, <span class="seriesInfo">DOI 10.17487/RFC6513</span>, <time datetime="2012-02" class="refDate">February 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6513">https://www.rfc-editor.org/info/rfc6513</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7716">[RFC7716]</dt>
      <dd>
<span class="refAuthor">Zhang, J.</span>, <span class="refAuthor">Giuliano, L.</span>, <span class="refAuthor">Rosen, E., Ed.</span>, <span class="refAuthor">Subramanian, K.</span>, and <span class="refAuthor">D. Pacella</span>, <span class="refTitle">"Global Table Multicast with BGP Multicast VPN (BGP-MVPN) Procedures"</span>, <span class="seriesInfo">RFC 7716</span>, <span class="seriesInfo">DOI 10.17487/RFC7716</span>, <time datetime="2015-12" class="refDate">December 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7716">https://www.rfc-editor.org/info/rfc7716</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="Acknowledgements">
<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 thank <span class="contact-name">Eric Rosen</span>,
         <span class="contact-name">Vinod Kumar</span>, <span class="contact-name">Yajun Liu</span>,
         <span class="contact-name">Stig Venaas</span>,
         <span class="contact-name">Mankamana Mishra</span>,
         <span class="contact-name">Gyan Mishra</span>, <span class="contact-name">Qin Wu</span>,
         and <span class="contact-name">Jia He</span> for their reviews, comments,
         questions, and suggestions for this document.<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">Zhaohui Zhang</span></div>
<div dir="auto" class="left"><span class="org">Juniper Networks</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:zzhang@juniper.net" class="email">zzhang@juniper.net</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Lenny Giuliano</span></div>
<div dir="auto" class="left"><span class="org">Juniper Networks</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:lenny@juniper.net" class="email">lenny@juniper.net</a>
</div>
</address>
</section>
</div>
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