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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 9035: A Routing Protocol for Low-Power and Lossy Networks (RPL) Destination‑Oriented Directed Acyclic Graph (DODAG) Configuration Option for the 6LoWPAN Routing Header</title>
<meta content="Pascal Thubert" name="author">
<meta content="Li Zhao" name="author">
<meta content="
       
     This document updates RFC 8138 by defining a bit in the Routing Protocol for Low-Power and Lossy Networks (RPL) Destination-Oriented Directed Acyclic Graph (DODAG)
     Configuration option to indicate whether compression is used within the
     RPL Instance and to specify the behavior of nodes compliant with RFC 8138 
     when the bit is set and unset.
       
    " name="description">
<meta content="xml2rfc 3.7.0" name="generator">
<meta content="IoT" name="keyword">
<meta content="Header Compression" name="keyword">
<meta content="Source Routing Header" name="keyword">
<meta content="Hop-by-Hop Header" name="keyword">
<meta content="RPL artifacts" name="keyword">
<meta content="9035" name="rfc.number">
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<link href="rfc9035.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,
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<table class="ears">
<thead><tr>
<td class="left">RFC 9035</td>
<td class="center">Turn On 6LoRH Compression</td>
<td class="right">April 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Thubert &amp; Zhao</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/rfc9035" class="eref">9035</a></dd>
<dt class="label-updates">Updates:</dt>
<dd class="updates">
<a href="https://www.rfc-editor.org/rfc/rfc8138" class="eref">8138</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="2021-04" class="published">April 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">P. Thubert, <span class="editor">Ed.</span>
</div>
<div class="org">Cisco Systems</div>
</div>
<div class="author">
      <div class="author-name">L. Zhao</div>
<div class="org">Cisco Systems</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9035</h1>
<h1 id="title">A Routing Protocol for Low-Power and Lossy Networks (RPL) Destination‑Oriented Directed Acyclic Graph (DODAG) Configuration Option for the 6LoWPAN Routing Header</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">
     This document updates RFC 8138 by defining a bit in the Routing Protocol for Low-Power and Lossy Networks (RPL) Destination-Oriented Directed Acyclic Graph (DODAG)
     Configuration option to indicate whether compression is used within the
     RPL Instance and to specify the behavior of nodes compliant with RFC 8138 
     when the bit is set and unset.<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/rfc9035">https://www.rfc-editor.org/info/rfc9035</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2021 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Simplified BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Simplified BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
</li>
          <li class="toc compact ulEmpty" 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="toc compact ulEmpty">
<li class="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-related-documents" class="xref">Related Documents</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.2.2.2">
                <p id="section-toc.1-1.2.2.2.1" class="keepWithNext"><a href="#section-2.2" class="xref">2.2</a>.  <a href="#name-glossary" class="xref">Glossary</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.2.2.3">
                <p id="section-toc.1-1.2.2.3.1"><a href="#section-2.3" class="xref">2.3</a>.  <a href="#name-requirements-language" class="xref">Requirements Language</a></p>
</li>
            </ul>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.3">
            <p id="section-toc.1-1.3.1"><a href="#section-3" class="xref">3</a>.  <a href="#name-extending-rfc-6550" class="xref">Extending RFC 6550</a></p>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.4">
            <p id="section-toc.1-1.4.1"><a href="#section-4" class="xref">4</a>.  <a href="#name-updating-rfc-8138" class="xref">Updating RFC 8138</a></p>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.5">
            <p id="section-toc.1-1.5.1"><a href="#section-5" class="xref">5</a>.  <a href="#name-transition-scenarios" class="xref">Transition Scenarios</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.5.2.1">
                <p id="section-toc.1-1.5.2.1.1"><a href="#section-5.1" class="xref">5.1</a>.  <a href="#name-coexistence" class="xref">Coexistence</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.2">
                <p id="section-toc.1-1.5.2.2.1"><a href="#section-5.2" class="xref">5.2</a>.  <a href="#name-inconsistent-state-while-mi" class="xref">Inconsistent State While Migrating</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.3">
                <p id="section-toc.1-1.5.2.3.1"><a href="#section-5.3" class="xref">5.3</a>.  <a href="#name-rolling-back" class="xref">Rolling Back</a></p>
</li>
            </ul>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-iana-considerations" class="xref">IANA Considerations</a></p>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#section-7" class="xref">7</a>.  <a href="#name-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#section-8" class="xref">8</a>.  <a href="#name-references" class="xref">References</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.8.2.1">
                <p id="section-toc.1-1.8.2.1.1"><a href="#section-8.1" class="xref">8.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.8.2.2">
                <p id="section-toc.1-1.8.2.2.1"><a href="#section-8.2" class="xref">8.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#section-appendix.a" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a></p>
</li>
          <li class="toc compact ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-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">
    The design of Low-Power and Lossy Networks (LLNs) is generally focused on
    saving energy, which is the most constrained resource of all. The routing
    optimizations in "<a href="#RFC6550" class="xref">RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks</a>" <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>, such as routing along a
    Destination-Oriented Directed Acyclic Graph (DODAG) to a Root Node and the
    associated routing header compression and forwarding technique specified in
    <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>, derive from that primary concern.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">
    Enabling <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> on a running network requires a "flag day",
    where the network is upgraded and rebooted.
    Otherwise, if acting as a leaf, a node that does not
    support compression per <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> would fail to communicate; if acting as a router, it
    would drop the compressed packets and black-hole a portion of the network.
    This specification enables a hot upgrade where a live network is migrated. During the migration, compression remains inactive until all nodes are upgraded.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">
    This document complements <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> and signals whether it
    should be used within a RPL DODAG with a new flag in the RPL DODAG
    Configuration option.
    The setting of this new flag is controlled by the Root and propagates as
    is in the whole network as part of the normal RPL signaling.<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">
      The flag is cleared to ensure that compression remains inactive during
      the migration phase. When the migration is complete (e.g., as known by
      network management and/or inventory), the flag is set and compression
      is globally activated in the whole DODAG.<a href="#section-1-4" class="pilcrow">¶</a></p>
</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>
<div id="lo">
<section id="section-2.1">
        <h3 id="name-related-documents">
<a href="#section-2.1" class="section-number selfRef">2.1. </a><a href="#name-related-documents" class="section-name selfRef">Related Documents</a>
        </h3>
<p id="section-2.1-1">
   The terminology used in this document is consistent with, and incorporates
   the terms provided in, "<a href="#RFC7102" class="xref">Terms Used in Routing for Low-Power and Lossy Networks</a>" <span>[<a href="#RFC7102" class="xref">RFC7102</a>]</span>.
   Other terms in use as related to LLNs are found in "<a href="#RFC7228" class="xref">Terminology for Constrained-Node Networks</a>" <span>[<a href="#RFC7228" class="xref">RFC7228</a>]</span>.<a href="#section-2.1-1" class="pilcrow">¶</a></p>
<p id="section-2.1-2">"RPL", "RPL Packet Information" (RPI), and "RPL Instance" (indexed by a
   RPLInstanceID) are defined in "<a href="#RFC6550" class="xref">RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks</a>" <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>.
 The RPI is the abstract
   information that RPL defines to be placed in data packets, e.g., as the RPL
   Option <span>[<a href="#RFC6553" class="xref">RFC6553</a>]</span> within the IPv6 Hop-By-Hop Header.
   By extension, the term "RPI" is often used to refer to the RPL Option itself.
   The DODAG Information Solicitation (DIS), Destination Advertisement Object
   (DAO), and DODAG Information Object (DIO) messages are also specified in
   <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>.<a href="#section-2.1-2" class="pilcrow">¶</a></p>
<p id="section-2.1-3">

   This document uses the terms "RPL-Unaware Leaf" (RUL) and "RPL-Aware Leaf"
   (RAL) consistently with <span><a href="#RFC9008" class="xref">"Using RPI Option Type, Routing Header for Source Routes, and IPv6-in-IPv6 Encapsulation in the RPL Data Plane"</a> [<a href="#RFC9008" class="xref">RFC9008</a>]</span>.
   The term "RPL-Aware Node" (RAN) refers to a node that is either
   a RAL or a RPL router. A RAN manages the reachability of its addresses and
   prefixes by injecting them in RPL by itself. In contrast, a RUL leverages
   "<a href="#RFC8505" class="xref">Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery</a>" <span>[<a href="#RFC8505" class="xref">RFC8505</a>]</span>
   to obtain reachability services from its parent router(s)
    as specified in <span><a href="#RFC9010" class="xref">"Routing for RPL (Routing Protocol for Low-Power and Lossy Networks) Leaves"</a> [<a href="#RFC9010" class="xref">RFC9010</a>]</span>.<a href="#section-2.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="gloss">
<section id="section-2.2">
        <h3 id="name-glossary">
<a href="#section-2.2" class="section-number selfRef">2.2. </a><a href="#name-glossary" class="section-name selfRef">Glossary</a>
        </h3>
<p id="section-2.2-1"> This document often uses the following abbreviations:<a href="#section-2.2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-2.2-2">
          <dt id="section-2.2-2.1">6LoRH:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.2">6LoWPAN Routing Header<a href="#section-2.2-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.3">6LoWPAN:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.4">IPv6 over Low-Power Wireless Personal Area Network<a href="#section-2.2-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.5">DIO:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.6"> DODAG Information Object (a RPL message)<a href="#section-2.2-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.7">DODAG:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.8"> Destination-Oriented Directed Acyclic Graph<a href="#section-2.2-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.9">LLN:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.10"> Low-Power and Lossy Network<a href="#section-2.2-2.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.11">MOP:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.12"> RPL Mode of Operation<a href="#section-2.2-2.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.13">RAL:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.14"> RPL-Aware Leaf<a href="#section-2.2-2.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.15">RAN:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.16"> RPL-Aware Node<a href="#section-2.2-2.16" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.17">RPI:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.18"> RPL Packet Information<a href="#section-2.2-2.18" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.19">RPL:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.20"> IPv6 Routing Protocol for Low-Power and Lossy Networks<a href="#section-2.2-2.20" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.21">RUL:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.22"> RPL-Unaware Leaf<a href="#section-2.2-2.22" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.23">SRH:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.24">Source Routing Header<a href="#section-2.2-2.24" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-2.2-2.25">Sub-DODAG:</dt>
          <dd style="margin-left: 1.5em" id="section-2.2-2.26">The sub-DODAG of a node is a DODAG rooted at that node that is a subset of a main DODAG the node belongs to. It is formed by the other nodes in the
main DODAG whose paths to the main DODAG root pass through that node.<a href="#section-2.2-2.26" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="bcp">
<section id="section-2.3">
        <h3 id="name-requirements-language">
<a href="#section-2.3" class="section-number selfRef">2.3. </a><a href="#name-requirements-language" class="section-name selfRef">Requirements Language</a>
        </h3>
<p id="section-2.3-1">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-2.3-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
<section id="section-3">
      <h2 id="name-extending-rfc-6550">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-extending-rfc-6550" class="section-name selfRef">Extending RFC 6550</a>
      </h2>
<p id="section-3-1">
   The DODAG Configuration option is defined in <span><a href="https://www.rfc-editor.org/rfc/rfc6550#section-6.7.6" class="relref">Section 6.7.6</a> of [<a href="#RFC6550" class="xref">RFC6550</a>]</span>. Its purpose is extended to distribute configuration
   information affecting the construction and maintenance of the DODAG, as
   well as operational parameters for RPL on the DODAG, through the DODAG.

   The DODAG Configuration option was originally
   designed with four bit positions reserved for future use as flags.<a href="#section-3-1" class="pilcrow">¶</a></p>
<span id="name-dodag-configuration-option-"></span><div id="RPLDCO">
<figure id="figure-1">
        <div class="artwork art-text alignCenter" id="section-3-2.1">
<pre>
 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   Type = 0x04 |Opt Length = 14| | |T| |A|       ...           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     +
                                &lt;- flags -&gt;</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-dodag-configuration-option-" class="selfRef">DODAG Configuration Option (Partial View)</a>
        </figcaption></figure>
</div>
<p id="section-3-3">
   This specification defines a new flag, "Enable Compression per RFC 8138 (T)".
   The 'T' flag is set to turn on the use of
   <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> within the DODAG. The 'T' flag is encoded
   in position 2 of the reserved flags in the DODAG Configuration option (counting from bit 0 as the most significant bit) and set to 0 in
   legacy implementations as specified in 
Sections <a href="https://www.rfc-editor.org/rfc/rfc6550#section-20.14" class="relref">20.14</a> and <a href="https://www.rfc-editor.org/rfc/rfc6550#section-6.7.6" class="relref">6.7.6</a> of <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>, respectively.<a href="#section-3-3" class="pilcrow">¶</a></p>
<p id="section-3-4">
   <span><a href="https://www.rfc-editor.org/rfc/rfc9008#section-4.1.2" class="relref">Section 4.1.2</a> of [<a href="#RFC9008" class="xref">RFC9008</a>]</span>
 updates
   <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span> to indicate that the definition of the flags applies to Mode of Operation (MOP) values zero (0) to six (6) only.
   For a MOP value of 7, <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> <span class="bcp14">MUST</span> be used on links where 6LoWPAN Header
   Compression <span>[<a href="#RFC6282" class="xref">RFC6282</a>]</span> applies and <span class="bcp14">MUST NOT</span> be used otherwise.<a href="#section-3-4" class="pilcrow">¶</a></p>
<p id="section-3-5">
   The RPL DODAG Configuration option is typically placed in
   a DIO message. The DIO message propagates down the
   DODAG to form and then maintain its structure. The DODAG Configuration option
   is copied unmodified from parents to children.


   <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span> states that "Nodes other than the DODAG root
   <span class="bcp14">MUST NOT</span> modify this information when propagating the DODAG Configuration option."
   Therefore, a legacy parent propagates the 'T' flag as set by the Root, and
   when the 'T' flag is set, it is transparently flooded to all the nodes in the DODAG.<a href="#section-3-5" class="pilcrow">¶</a></p>
</section>
<section id="section-4">
      <h2 id="name-updating-rfc-8138">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-updating-rfc-8138" class="section-name selfRef">Updating RFC 8138</a>
      </h2>
<p id="section-4-1">
   A node <span class="bcp14">SHOULD</span> generate packets in compressed form using
   <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> if and only if the 'T' flag
   is set. This behavior can be overridden by configuration or network
   management. Overriding may be needed, e.g., to turn on compression in a
   network where all nodes support <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> but the Root does
   not support this specification and cannot set the 'T' flag, or to disable it
   locally in case of a problem.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">
   The decision to use <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> is made by the originator of
   the packet, depending on its capabilities and its knowledge of the state of
   the 'T' flag.
   A router encapsulating a packet is the originator of the resulting
   packet and is responsible for compressing the outer headers per 
   <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>, but it <span class="bcp14">MUST NOT</span> perform compression on the encapsulated packet.<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3">
   An external target <span>[<a href="#RFC9008" class="xref">RFC9008</a>]</span> is not
   expected to support <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>. In most cases, packets to and
   from an external target are tunneled back and forth between the border router
   (referred to as a 6LoWPAN Router (6LR)) that serves the external target and the Root, regardless
   of the MOP used in the RPL DODAG.
   The inner packet is typically not compressed per <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>,
   so for outgoing packets, the border router just needs to decapsulate the
   (compressed) outer header and forward the (uncompressed) inner packet towards
   the external target.<a href="#section-4-3" class="pilcrow">¶</a></p>
<p id="section-4-4">
   A border router that forwards a packet to an external target <span class="bcp14">MUST</span>
   uncompress the packet first. In all other cases, a router <span class="bcp14">MUST</span>
   forward a packet in the form that the source used, either compressed or 
   uncompressed.<a href="#section-4-4" class="pilcrow">¶</a></p>
<p id="section-4-5">
   A RUL <span>[<a href="#RFC9010" class="xref">RFC9010</a>]</span> is both a leaf and an
   external target. A RUL does not participate in RPL and
   depends on the parent router to obtain connectivity. In the case of a RUL,
   forwarding towards an external target actually means delivering the packet.<a href="#section-4-5" class="pilcrow">¶</a></p>
</section>
<section id="section-5">
      <h2 id="name-transition-scenarios">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-transition-scenarios" class="section-name selfRef">Transition Scenarios</a>
      </h2>
<p id="section-5-1">
   A node that supports <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> but not this specification
   can only be used in a homogeneous network.
   Enabling compression per <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> without a turn-on signaling
   method requires a flag day, by which time all nodes must be upgraded and
   at which point the network can be rebooted with 6LoRH compression <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> turned on.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">
   The intent of this specification is to perform a migration once and for all,
   without the need for a flag day. In particular, the intent is not to
   undo the setting of the 'T' flag.
   Though it is possible to roll back (see <a href="#rb" class="xref">Section 5.3</a>), the rollback
   operation <span class="bcp14">SHOULD</span> be complete before the network operator adds nodes
   that do not support <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>.<a href="#section-5-2" class="pilcrow">¶</a></p>
<div id="coex">
<section id="section-5.1">
        <h3 id="name-coexistence">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-coexistence" class="section-name selfRef">Coexistence</a>
        </h3>
<p id="section-5.1-1">
    A node that supports this specification can operate in a network with 6LoRH
    compression <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> turned on or off with the 'T' flag set
    accordingly and in a network in transition from off to on or on to off
    (see <a href="#mig" class="xref">Section 5.2</a>).<a href="#section-5.1-1" class="pilcrow">¶</a></p>
<p id="section-5.1-2">
    A node that does not support <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> can interoperate with
    nodes that do in a network with 6LoRH compression <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> turned
    off. If compression is turned on, all the RANs are expected
    to be able to handle packets in compressed form. A node that
    cannot do so may remain connected to the network as a RUL as described in
    <span>[<a href="#RFC9010" class="xref">RFC9010</a>]</span>.<a href="#section-5.1-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="mig">
<section id="section-5.2">
        <h3 id="name-inconsistent-state-while-mi">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-inconsistent-state-while-mi" class="section-name selfRef">Inconsistent State While Migrating</a>
        </h3>
<p id="section-5.2-1">
   When the 'T' flag is turned on by the Root, the
   information slowly percolates through the DODAG as the DIO gets propagated.
   Some nodes will see the flag and start sourcing packets in compressed
   form, while other nodes in the same RPL DODAG will still not be aware of it.
   In Non-Storing mode, the Root will start using
   <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> with a Source Routing Header 6LoRH (SRH-6LoRH)
   that routes all the way to the parent router or to the leaf.<a href="#section-5.2-1" class="pilcrow">¶</a></p>
<p id="section-5.2-2">
   To ensure that a packet is forwarded across the RPL DODAG in the form in
   which it was generated, it is required that all the RPL nodes support
   <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> at the time of the switch.<a href="#section-5.2-2" class="pilcrow">¶</a></p>
<p id="section-5.2-3">
   Setting the 'T' flag is ultimately the responsibility of the network
   administrator. The expectation is that the network management or upgrading
   tools in place enable the network administrator to know when all the nodes
   that may join a DODAG were migrated. In the case of a RPL Instance with
   multiple Roots, all nodes that participate in the RPL Instance may
   potentially join any DODAG.
   The network <span class="bcp14">MUST</span> be operated with the 'T' flag unset until all nodes in the
   RPL Instance are upgraded to support this specification.<a href="#section-5.2-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="rb">
<section id="section-5.3">
        <h3 id="name-rolling-back">
<a href="#section-5.3" class="section-number selfRef">5.3. </a><a href="#name-rolling-back" class="section-name selfRef">Rolling Back</a>
        </h3>
<p id="section-5.3-1">
   When turning 6LoRH compression <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> off in the network, the
   network administrator <span class="bcp14">MUST</span> wait until each node has its 'T' flag
   unset before allowing nodes that do not support compression in
   the network. Information regarding whether compression is active in a node
   <span class="bcp14">SHOULD</span> be exposed in the node's management interface.<a href="#section-5.3-1" class="pilcrow">¶</a></p>
<p id="section-5.3-2">
   Nodes that do not support <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span> <span class="bcp14">SHOULD NOT</span> be deployed
   in a network where compression is turned on. If that is done, the node
   can only operate as a RUL.<a href="#section-5.3-2" class="pilcrow">¶</a></p>
</section>
</div>
</section>
<div id="iana">
<section id="section-6">
      <h2 id="name-iana-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-6-1">
    This specification updates the "DODAG Configuration Option Flags for MOP      
0..6" registry <span>[<a href="#RFC9008" class="xref">RFC9008</a>]</span> (formerly the "DODAG Configuration Option Flags" registry, which was created for <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>), by allocating one
 new flag as follows:<a href="#section-6-1" class="pilcrow">¶</a></p>
<span id="name-new-dodag-configuration-opt"></span><div id="nexndopt">
<table class="center" id="table-1">
        <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-new-dodag-configuration-opt" class="selfRef">New DODAG Configuration Option Flag</a>
        </caption>
<thead>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">Bit Number</td>
            <td class="text-left" rowspan="1" colspan="1">Capability Description</td>
            <td class="text-left" rowspan="1" colspan="1">Reference</td>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">2</td>
            <td class="text-left" rowspan="1" colspan="1">Enable Compression per RFC 8138 (T)</td>
            <td class="text-left" rowspan="1" colspan="1">RFC 9035</td>
          </tr>
        </tbody>
      </table>
</div>
<p id="section-6-3">IANA has added this document as a reference for MOP 7 in the RPL "Mode of Operation" registry.<a href="#section-6-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="sec">
<section id="section-7">
      <h2 id="name-security-considerations">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-7-1">
   It is worth noting that in RPL <span>[<a href="#RFC6550" class="xref">RFC6550</a>]</span>, every node in the
   LLN that is RPL aware and has access to the RPL domain can inject any RPL-based attack in the network; see <span>[<a href="#RFC7416" class="xref">RFC7416</a>]</span> for details.
   This document typically applies to an existing deployment and does not change
   its security requirements and operations.
   It is assumed that the security mechanisms as defined for RPL are followed.<a href="#section-7-1" class="pilcrow">¶</a></p>
<p id="section-7-2">
    Setting the 'T' flag before all routers are upgraded may cause a loss
    of packets. The new bit benefits from the same protection as the rest of the
    information in the DODAG Configuration option that transports it. Touching
    the new bit is just one of the many attacks that can happen if an
    attacker manages to inject a corrupted configuration option in the network.<a href="#section-7-2" class="pilcrow">¶</a></p>
<p id="section-7-3">
    Setting and unsetting the 'T' flag may create inconsistencies in the network,
    but as long as all nodes are upgraded to provide support for <span>[<a href="#RFC8138" class="xref">RFC8138</a>]</span>, 
    they will be able to forward both forms. The source is responsible
    for selecting whether the packet is compressed or not, and all routers must
    use the format that the source selected. So, the result of an inconsistency
    is merely that both forms will be present in the network, at an additional
    cost of bandwidth for packets in uncompressed form.<a href="#section-7-3" class="pilcrow">¶</a></p>
<p id="section-7-4">
    An attacker may unset the 'T' flag to force additional energy consumption of child or descendant nodes in its sub-DODAG.
    Conversely, it may set the 'T' flag so
    that nodes located downstream would compress packets even when compression is not desired, potentially causing packet loss.  In a tree structure, the attacker would be in a position to drop the packets from and to the attacked nodes.  So, the attacks mentioned above would be more complex and more visible than simply dropping selected packets.  The downstream node may have other parents and see the bit with both
settings; such a situation may be detected, and an alert may be triggered.<a href="#section-7-4" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-8">
      <h2 id="name-references">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-8.1">
        <h3 id="name-normative-references">
<a href="#section-8.1" class="section-number selfRef">8.1. </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="RFC6550">[RFC6550]</dt>
        <dd>
<span class="refAuthor">Winter, T., Ed.</span>, <span class="refAuthor">Thubert, P., Ed.</span>, <span class="refAuthor">Brandt, A.</span>, <span class="refAuthor">Hui, J.</span>, <span class="refAuthor">Kelsey, R.</span>, <span class="refAuthor">Levis, P.</span>, <span class="refAuthor">Pister, K.</span>, <span class="refAuthor">Struik, R.</span>, <span class="refAuthor">Vasseur, JP.</span>, and <span class="refAuthor">R. Alexander</span>, <span class="refTitle">"RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks"</span>, <span class="seriesInfo">RFC 6550</span>, <span class="seriesInfo">DOI 10.17487/RFC6550</span>, <time datetime="2012-03" class="refDate">March 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6550">https://www.rfc-editor.org/info/rfc6550</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7102">[RFC7102]</dt>
        <dd>
<span class="refAuthor">Vasseur, JP.</span>, <span class="refTitle">"Terms Used in Routing for Low-Power and Lossy Networks"</span>, <span class="seriesInfo">RFC 7102</span>, <span class="seriesInfo">DOI 10.17487/RFC7102</span>, <time datetime="2014-01" class="refDate">January 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7102">https://www.rfc-editor.org/info/rfc7102</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8138">[RFC8138]</dt>
        <dd>
<span class="refAuthor">Thubert, P., Ed.</span>, <span class="refAuthor">Bormann, C.</span>, <span class="refAuthor">Toutain, L.</span>, and <span class="refAuthor">R. Cragie</span>, <span class="refTitle">"IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Routing Header"</span>, <span class="seriesInfo">RFC 8138</span>, <span class="seriesInfo">DOI 10.17487/RFC8138</span>, <time datetime="2017-04" class="refDate">April 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8138">https://www.rfc-editor.org/info/rfc8138</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
        <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8505">[RFC8505]</dt>
        <dd>
<span class="refAuthor">Thubert, P., Ed.</span>, <span class="refAuthor">Nordmark, E.</span>, <span class="refAuthor">Chakrabarti, S.</span>, and <span class="refAuthor">C. Perkins</span>, <span class="refTitle">"Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery"</span>, <span class="seriesInfo">RFC 8505</span>, <span class="seriesInfo">DOI 10.17487/RFC8505</span>, <time datetime="2018-11" class="refDate">November 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8505">https://www.rfc-editor.org/info/rfc8505</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9010">[RFC9010]</dt>
      <dd>
<span class="refAuthor">Thubert, P., Ed.</span> and <span class="refAuthor">M. Richardson</span>, <span class="refTitle">"Routing for RPL (Routing Protocol for Low-Power and Lossy Networks) Leaves"</span>, <span class="seriesInfo">RFC 9010</span>, <span class="seriesInfo">DOI 10.17487/RFC9010</span>, <time datetime="2021-04" class="refDate">April 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9010">https://www.rfc-editor.org/info/rfc9010</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-8.2">
        <h3 id="name-informative-references">
<a href="#section-8.2" class="section-number selfRef">8.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="RFC6282">[RFC6282]</dt>
        <dd>
<span class="refAuthor">Hui, J., Ed.</span> and <span class="refAuthor">P. Thubert</span>, <span class="refTitle">"Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks"</span>, <span class="seriesInfo">RFC 6282</span>, <span class="seriesInfo">DOI 10.17487/RFC6282</span>, <time datetime="2011-09" class="refDate">September 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6282">https://www.rfc-editor.org/info/rfc6282</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6553">[RFC6553]</dt>
        <dd>
<span class="refAuthor">Hui, J.</span> and <span class="refAuthor">JP. Vasseur</span>, <span class="refTitle">"The Routing Protocol for Low-Power and Lossy Networks (RPL) Option for Carrying RPL Information in Data-Plane Datagrams"</span>, <span class="seriesInfo">RFC 6553</span>, <span class="seriesInfo">DOI 10.17487/RFC6553</span>, <time datetime="2012-03" class="refDate">March 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6553">https://www.rfc-editor.org/info/rfc6553</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7228">[RFC7228]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span>, <span class="refAuthor">Ersue, M.</span>, and <span class="refAuthor">A. Keranen</span>, <span class="refTitle">"Terminology for Constrained-Node Networks"</span>, <span class="seriesInfo">RFC 7228</span>, <span class="seriesInfo">DOI 10.17487/RFC7228</span>, <time datetime="2014-05" class="refDate">May 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7228">https://www.rfc-editor.org/info/rfc7228</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7416">[RFC7416]</dt>
        <dd>
<span class="refAuthor">Tsao, T.</span>, <span class="refAuthor">Alexander, R.</span>, <span class="refAuthor">Dohler, M.</span>, <span class="refAuthor">Daza, V.</span>, <span class="refAuthor">Lozano, A.</span>, and <span class="refAuthor">M. Richardson, Ed.</span>, <span class="refTitle">"A Security Threat Analysis for the Routing Protocol for Low-Power and Lossy Networks (RPLs)"</span>, <span class="seriesInfo">RFC 7416</span>, <span class="seriesInfo">DOI 10.17487/RFC7416</span>, <time datetime="2015-01" class="refDate">January 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7416">https://www.rfc-editor.org/info/rfc7416</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9008">[RFC9008]</dt>
      <dd>
<span class="refAuthor">Robles, M.I.</span>, <span class="refAuthor">Richardson, M.</span>, and <span class="refAuthor">P. Thubert</span>, <span class="refTitle">"Using RPI Option Type, Routing Header for Source Routes, and IPv6-in-IPv6 Encapsulation in the RPL Data Plane"</span>, <span class="seriesInfo">RFC 9008</span>, <span class="seriesInfo">DOI 10.17487/RFC9008</span>, <time datetime="2021-04" class="refDate">April 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9008">https://www.rfc-editor.org/info/rfc9008</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<section id="section-appendix.a">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="section-appendix.a-1">
   The authors wish to thank
   <span class="contact-name">Murray Kucherawy</span>, <span class="contact-name">Meral Shirazipour</span>, <span class="contact-name">Barry Leiba</span>, <span class="contact-name">Tirumaleswar Reddy</span>,
   <span class="contact-name">Nagendra Kumar Nainar</span>, <span class="contact-name">Stewart Bryant</span>, <span class="contact-name">Carles Gomez</span>, <span class="contact-name">Éric Vyncke</span>,
   <span class="contact-name">Roman Danyliw</span>,
   and especially <span class="contact-name">Benjamin Kaduk</span>, <span class="contact-name">Alvaro Retana</span>, <span class="contact-name">Dominique Barthel</span>,
   and <span class="contact-name">Rahul Jadhav</span> for their in-depth reviews and constructive suggestions.<a href="#section-appendix.a-1" class="pilcrow">¶</a></p>
<p id="section-appendix.a-2">
   Also, many thanks to <span class="contact-name">Michael Richardson</span> for always being  helpful and responsive when the need arises.<a href="#section-appendix.a-2" class="pilcrow">¶</a></p>
</section>
<div id="authors-addresses">
<section id="section-appendix.b">
      <h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Pascal Thubert (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div dir="auto" class="left"><span class="extended-address">Building D</span></div>
<div dir="auto" class="left"><span class="street-address">45 Allee des Ormes - BP1200</span></div>
<div dir="auto" class="left">
<span class="postal-code">06254</span> <span class="locality">MOUGINS - Sophia Antipolis</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="tel">
<span>Phone:</span>
<a href="tel:+33%20497%2023%2026%2034" class="tel">+33 497 23 26 34</a>
</div>
<div class="email">
<span>Email:</span>
<a href="mailto:pthubert@cisco.com" class="email">pthubert@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Li Zhao</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems, Inc.</span></div>
<div dir="auto" class="left"><span class="extended-address">Xinsi Building</span></div>
<div dir="auto" class="left"><span class="street-address">No. 926 Yi Shan Rd</span></div>
<div dir="auto" class="left"><span class="locality">Shanghai</span></div>
<div dir="auto" class="left"><span class="postal-code">200233</span></div>
<div dir="auto" class="left"><span class="country-name">China</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:liz3@cisco.com" class="email">liz3@cisco.com</a>
</div>
</address>
</section>
</div>
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