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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" category="info"
    ipr="trust200902" consensus="true" docName="draft-ietf-opsec-ipv6-eh-filtering-10" > indexInclude="true" ipr="trust200902" number="9288" prepTime="2022-08-18T16:08:19" scripts="Common,Latin" sortRefs="true" submissionType="IETF" symRefs="true" tocDepth="2" tocInclude="true" xml:lang="en">
  <link href="https://datatracker.ietf.org/doc/draft-ietf-opsec-ipv6-eh-filtering-10" rel="prev"/>
  <link href="https://dx.doi.org/10.17487/rfc9288" rel="alternate"/>
  <link href="urn:issn:2070-1721" rel="alternate"/>
  <front>
    <title abbrev="Filtering of IPv6 packets Packets with EHs">Recommendations on the Filtering of IPv6 Packets Containing IPv6 Extension Headers at Transit Routers</title>

    <!-- add 'role="editor"' below for the editors if appropriate -->
    <seriesInfo name="RFC" value="9288" stream="IETF"/>
    <author fullname="Fernando Gont" initials="F." surname="Gont">
      <organization abbrev="EdgeUno">EdgeUno</organization> abbrev="SI6 Networks" showOnFrontPage="true">SI6 Networks</organization>
      <address>
        <postal>
          <street>Segurola y Habana 4310, 4310 7mo Piso</street>
          <city>Villa Devoto</city>
          <region>Ciudad piso</street>
          <city>Ciudad Autonoma de Buenos Aires</region> Aires</city>
          <country>Argentina</country>
        </postal>
        <email>fernando.gont@edgeuno.com</email>
        <uri>https://www.edgeuno.com</uri>
        <email>fgont@si6networks.com</email>
        <uri>https://www.si6networks.com</uri>
      </address>
    </author>
    <author fullname="Will (Shucheng) Liu" initials="W." surname="Liu">
      <organization>Huawei
      <organization showOnFrontPage="true">Huawei Technologies</organization>
      <address>
        <postal>
          <street>Bantian, Longgang District</street>
          <city>Shenzhen</city>
          <code>518129</code>
          <country>P.R. China</country>
          <country>China</country>
        </postal>
        <email>liushucheng@huawei.com</email>
      </address>
    </author>

<!--
    <author fullname="Ronald P. Bonica" initials="R." surname="Bonica">
      <organization>Juniper Networks</organization>

      <address>
        <postal>
          <street>2251 Corporate Park Drive</street>

          <city>Herndon</city>

          <region>VA</region>

          <code>20171</code>

          <country>US</country>
        </postal>

        <phone>571 250 5819</phone>

        <email>rbonica@juniper.net</email>
      </address>
    </author>
-->
    <date />
<!-- month="May" is no longer necessary note also, day="30" is optional --> month="08" year="2022"/>
    <area>Operations and Management (ops)</area>    <!-- WG name at the upperleft corner of the doc,
         IETF fine for individual submissions -->
    <workgroup>opsec</workgroup>

<abstract>
<t>
    <keyword>Denial of Service</keyword>
    <keyword>Distributed Denial of Service</keyword>
    <keyword>DoS</keyword>
    <keyword>DDoS</keyword>
    <keyword>ACL</keyword>
    <keyword>filtering policy</keyword>
    <abstract pn="section-abstract">
      <t indent="0" pn="section-abstract-1">
   This document analyzes the security implications of IPv6 Extension Headers and associated IPv6 options. Additionally, it discusses the operational and
   interoperability implications of discarding packets based on the
   IPv6 Extension Headers and IPv6 options they contain. Finally, it provides advice on the filtering of such IPv6
   packets at transit routers for traffic not directed to them, for those cases where such filtering is deemed as necessary.
</t>
    </abstract>
    <boilerplate>
      <section anchor="status-of-memo" numbered="false" removeInRFC="false" toc="exclude" pn="section-boilerplate.1">
        <name slugifiedName="name-status-of-this-memo">Status of This Memo</name>
        <t indent="0" pn="section-boilerplate.1-1">
            This document is not an Internet Standards Track specification; it is
            published for informational purposes.
        </t>
        <t indent="0" pn="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).  Not all documents
            approved by the IESG are candidates for any level of Internet
            Standard; see Section 2 of RFC 7841.
        </t>
        <t indent="0" pn="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
            <eref target="https://www.rfc-editor.org/info/rfc9288" brackets="none"/>.
        </t>
      </section>
      <section anchor="copyright" numbered="false" removeInRFC="false" toc="exclude" pn="section-boilerplate.2">
        <name slugifiedName="name-copyright-notice">Copyright Notice</name>
        <t indent="0" pn="section-boilerplate.2-1">
            Copyright (c) 2022 IETF Trust and the persons identified as the
            document authors. All rights reserved.
        </t>
        <t indent="0" pn="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<eref target="https://trustee.ietf.org/license-info" brackets="none"/>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Revised BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Revised BSD License.
        </t>
      </section>
    </boilerplate>
    <toc>
      <section anchor="toc" numbered="false" removeInRFC="false" toc="exclude" pn="section-toc.1">
        <name slugifiedName="name-table-of-contents">Table of Contents</name>
        <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1">
          <li pn="section-toc.1-1.1">
            <t indent="0" keepWithNext="true" pn="section-toc.1-1.1.1"><xref derivedContent="1" format="counter" sectionFormat="of" target="section-1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-introduction">Introduction</xref></t>
          </li>
          <li pn="section-toc.1-1.2">
            <t indent="0" pn="section-toc.1-1.2.1"><xref derivedContent="2" format="counter" sectionFormat="of" target="section-2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-terminology-and-assumptions">Terminology and Assumptions Employed in This Document</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.2.2">
              <li pn="section-toc.1-1.2.2.1">
                <t indent="0" keepWithNext="true" pn="section-toc.1-1.2.2.1.1"><xref derivedContent="2.1" format="counter" sectionFormat="of" target="section-2.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-terminology">Terminology</xref></t>
              </li>
              <li pn="section-toc.1-1.2.2.2">
                <t indent="0" keepWithNext="true" pn="section-toc.1-1.2.2.2.1"><xref derivedContent="2.2" format="counter" sectionFormat="of" target="section-2.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-applicability-statement">Applicability Statement</xref></t>
              </li>
              <li pn="section-toc.1-1.2.2.3">
                <t indent="0" pn="section-toc.1-1.2.2.3.1"><xref derivedContent="2.3" format="counter" sectionFormat="of" target="section-2.3"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-router-default-behavior-and">Router Default Behavior and Features</xref></t>
              </li>
            </ul>
          </li>
          <li pn="section-toc.1-1.3">
            <t indent="0" pn="section-toc.1-1.3.1"><xref derivedContent="3" format="counter" sectionFormat="of" target="section-3"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-ipv6-extension-headers">IPv6 Extension Headers</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.3.2">
              <li pn="section-toc.1-1.3.2.1">
                <t indent="0" pn="section-toc.1-1.3.2.1.1"><xref derivedContent="3.1" format="counter" sectionFormat="of" target="section-3.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-general-discussion">General Discussion</xref></t>
              </li>
              <li pn="section-toc.1-1.3.2.2">
                <t indent="0" pn="section-toc.1-1.3.2.2.1"><xref derivedContent="3.2" format="counter" sectionFormat="of" target="section-3.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-general-security-implicatio">General Security Implications</xref></t>
              </li>
              <li pn="section-toc.1-1.3.2.3">
                <t indent="0" pn="section-toc.1-1.3.2.3.1"><xref derivedContent="3.3" format="counter" sectionFormat="of" target="section-3.3"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-rationale-for-our-advice-on">Rationale for Our Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers</xref></t>
              </li>
              <li pn="section-toc.1-1.3.2.4">
                <t indent="0" pn="section-toc.1-1.3.2.4.1"><xref derivedContent="3.4" format="counter" sectionFormat="of" target="section-3.4"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-summary-of-advice-on-the-ha">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers</xref></t>
              </li>
              <li pn="section-toc.1-1.3.2.5">
                <t indent="0" pn="section-toc.1-1.3.2.5.1"><xref derivedContent="3.5" format="counter" sectionFormat="of" target="section-3.5"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-advice-on-the-handling-of-i">Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers</xref></t>
              </li>
              <li pn="section-toc.1-1.3.2.6">
                <t indent="0" pn="section-toc.1-1.3.2.6.1"><xref derivedContent="3.6" format="counter" sectionFormat="of" target="section-3.6"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-advice-on-the-handling-of-p">Advice on the Handling of Packets with Unknown IPv6 Extension Headers</xref></t>
              </li>
            </ul>
          </li>
          <li pn="section-toc.1-1.4">
            <t indent="0" pn="section-toc.1-1.4.1"><xref derivedContent="4" format="counter" sectionFormat="of" target="section-4"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-ipv6-options">IPv6 Options</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.4.2">
              <li pn="section-toc.1-1.4.2.1">
                <t indent="0" pn="section-toc.1-1.4.2.1.1"><xref derivedContent="4.1" format="counter" sectionFormat="of" target="section-4.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-general-discussion-2">General Discussion</xref></t>
              </li>
              <li pn="section-toc.1-1.4.2.2">
                <t indent="0" pn="section-toc.1-1.4.2.2.1"><xref derivedContent="4.2" format="counter" sectionFormat="of" target="section-4.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-general-security-implication">General Security Implications of IPv6 Options</xref></t>
              </li>
              <li pn="section-toc.1-1.4.2.3">
                <t indent="0" pn="section-toc.1-1.4.2.3.1"><xref derivedContent="4.3" format="counter" sectionFormat="of" target="section-4.3"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-summary-of-advice-on-the-hand">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 Options</xref></t>
              </li>
              <li pn="section-toc.1-1.4.2.4">
                <t indent="0" pn="section-toc.1-1.4.2.4.1"><xref derivedContent="4.4" format="counter" sectionFormat="of" target="section-4.4"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-advice-on-the-handling-of-pa">Advice on the Handling of Packets with Specific IPv6 Options</xref></t>
              </li>
              <li pn="section-toc.1-1.4.2.5">
                <t indent="0" pn="section-toc.1-1.4.2.5.1"><xref derivedContent="4.5" format="counter" sectionFormat="of" target="section-4.5"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-advice-on-the-handling-of-pac">Advice on the Handling of Packets with Unknown IPv6 Options</xref></t>
              </li>
            </ul>
          </li>
          <li pn="section-toc.1-1.5">
            <t indent="0" pn="section-toc.1-1.5.1"><xref derivedContent="5" format="counter" sectionFormat="of" target="section-5"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-iana-considerations">IANA Considerations</xref></t>
          </li>
          <li pn="section-toc.1-1.6">
            <t indent="0" pn="section-toc.1-1.6.1"><xref derivedContent="6" format="counter" sectionFormat="of" target="section-6"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-privacy-considerations">Privacy Considerations</xref></t>
          </li>
          <li pn="section-toc.1-1.7">
            <t indent="0" pn="section-toc.1-1.7.1"><xref derivedContent="7" format="counter" sectionFormat="of" target="section-7"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-security-considerations">Security Considerations</xref></t>
          </li>
          <li pn="section-toc.1-1.8">
            <t indent="0" pn="section-toc.1-1.8.1"><xref derivedContent="8" format="counter" sectionFormat="of" target="section-8"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-references">References</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.8.2">
              <li pn="section-toc.1-1.8.2.1">
                <t indent="0" pn="section-toc.1-1.8.2.1.1"><xref derivedContent="8.1" format="counter" sectionFormat="of" target="section-8.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-normative-references">Normative References</xref></t>
              </li>
              <li pn="section-toc.1-1.8.2.2">
                <t indent="0" pn="section-toc.1-1.8.2.2.1"><xref derivedContent="8.2" format="counter" sectionFormat="of" target="section-8.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-informative-references">Informative References</xref></t>
              </li>
            </ul>
          </li>
          <li pn="section-toc.1-1.9">
            <t indent="0" pn="section-toc.1-1.9.1"><xref derivedContent="" format="none" sectionFormat="of" target="section-appendix.a"/><xref derivedContent="" format="title" sectionFormat="of" target="name-acknowledgements">Acknowledgements</xref></t>
          </li>
          <li pn="section-toc.1-1.10">
            <t indent="0" pn="section-toc.1-1.10.1"><xref derivedContent="" format="none" sectionFormat="of" target="section-appendix.b"/><xref derivedContent="" format="title" sectionFormat="of" target="name-authors-addresses">Authors' Addresses</xref></t>
          </li>
        </ul>
      </section>
    </toc>
  </front>
  <middle>
    <section title="Introduction" anchor="intro">
<t>IPv6 anchor="intro" numbered="true" toc="include" removeInRFC="false" pn="section-1">
      <name slugifiedName="name-introduction">Introduction</name>
      <t indent="0" pn="section-1-1">IPv6 Extension Headers (EHs) allow for the extension of the IPv6
   protocol,
   protocol and provide support for core functionality functionality, such as IPv6
   fragmentation.  However, common implementation limitations suggest that EHs present a challenge for IPv6 packet routing equipment, particularly when the IPv6 header chain needs to be processed for e.g. for, as an example, enforcing ACLs Access Control Lists (ACLs) or implementing other functions <xref target="RFC9098"/>. target="RFC9098" format="default" sectionFormat="of" derivedContent="RFC9098"/>.
</t>

<t>Several
      <t indent="0" pn="section-1-2">Several studies (e.g. <xref target="Huston-2022"/>, (e.g., <xref target="I-D.vyncke-v6ops-james"/>, target="Huston-2022" format="default" sectionFormat="of" derivedContent="Huston-2022"/>, <xref target="I-D.vyncke-v6ops-james" format="default" sectionFormat="of" derivedContent="JAMES"/>, and <xref target="RFC7872"/>) target="RFC7872" format="default" sectionFormat="of" derivedContent="RFC7872"/>) suggest that there is widespread dropping of IPv6 packets that contain IPv6 Extension Headers (EHs). EHs. In some cases, such packet drops occur at transit routers. While some operators are known to intentionally drop packets that contain IPv6 EHs, it is possible that some of the measured packet drops are the result of inappropriate advice in this area.</t>

<t>This
      <t indent="0" pn="section-1-3">This document analyzes both the general security implications of
   IPv6 EHs, as well as the security implications of
   specific EH and Option option types. It also provides advice on the
   filtering of IPv6 packets based on the IPv6 EHs and
   the IPv6 options they contain. Since
   various protocols may use IPv6 EHs (possibly with IPv6
   options), discarding packets based on the IPv6 EHs or
   IPv6 options they contain can have implications on the proper
   functioning of such protocols.  Thus, this document also attempts to
   discuss the operational and interoperability implications of such
   filtering policies.</t>

<t>The
      <t indent="0" pn="section-1-4">The resulting packet filtering policy typically depends on where in the network such policy is enforced: when enforced. When the policy is enforced in a transit network, the policy typically follows a "deny-list" approach, where only packets with clear negative implications are dropped. On the other hand, when the policy is enforced closer to the destination systems, the policy typically follows an "accept-list" approach, where only traffic that is expected to be received is allowed. The advice in this document is aimed only at transit routers that may need to enforce a filtering policy based on the IPv6 EHs and IPv6 options a packet may contain, following a "deny-list" approach, and hence approach; hence, it is likely to be much more permissive than a filtering policy to be employed at e.g. at, for example, the edge of an enterprise network. The advice in this document is meant to improve the current situation of the dropping of packets with IPv6 EHs in the Internet <xref target="RFC7872"/> target="RFC7872" format="default" sectionFormat="of" derivedContent="RFC7872"/> in such cases where packets are being dropped due to inappropriate or missing guidelines.</t>

<t>This
      <t indent="0" pn="section-1-5">This document is similar in nature to
   <xref target="RFC7126"/>, target="RFC7126" format="default" sectionFormat="of" derivedContent="RFC7126"/>, which addresses the same problem for the IPv4 case. However, in IPv6, the problem space is compounded by the fact that IPv6 specifies a number of IPv6 EHs, EHs and a number of IPv6 options which that may be valid only when included in specific EH types.</t>

<t>This
      <t indent="0" pn="section-1-6">This document completes and complements the considerations for protecting the control plane from packets containing IP options that can be found in <xref target="RFC6192"/>.</t>

<t><xref target="terms"/> target="RFC6192" format="default" sectionFormat="of" derivedContent="RFC6192"/>.</t>
      <t indent="0" pn="section-1-7"><xref target="terms" format="default" sectionFormat="of" derivedContent="Section 2"/> specifies the terminology and conventions employed throughout this document. <xref target="ipv6-extension-headers-discussion"/> target="ipv6-extension-headers-discussion" format="default" sectionFormat="of" derivedContent="Section 3"/> discusses IPv6 EHs and provides advice in the area of filtering IPv6 packets that contain such IPv6 EHs. <xref target="ipv6-options-discussion"/> target="ipv6-options-discussion" format="default" sectionFormat="of" derivedContent="Section 4"/> discusses IPv6 options and provides advice in the area of filtering IPv6 packets that contain such options.  <!-- <xref target="upper-layer"/> specifies the filtering of packets based on the upper-layer protocol. Specifically, it identifies upper-layer protocols that, for different reasons, should not be present in IPv6 packets. -->
      </t>

<!--
<t>While this document is similar in structure and nature to <xref target="RFC7123"/>, we note that this document is aimed at firewall administrators, an hence tends to be more restrictive than what an IPv6-version of <xref target="RFC7123"/> would be.</t>
-->
    </section>
    <section title="Terminology anchor="terms" numbered="true" toc="include" removeInRFC="false" pn="section-2">
      <name slugifiedName="name-terminology-and-assumptions">Terminology and Assumptions Employed in This Document"
    anchor="terms"> Document</name>
      <section title="Terminology">

<t>The numbered="true" toc="include" removeInRFC="false" pn="section-2.1">
        <name slugifiedName="name-terminology">Terminology</name>
        <t indent="0" pn="section-2.1-1">The terms "permit" (allow the traffic), "drop" (drop with no notification to sender), and "reject" (drop with appropriate notification to sender) are employed as defined in <xref target="RFC3871"/>. target="RFC3871" format="default" sectionFormat="of" derivedContent="RFC3871"/>. Throughout this document document, we also employ the term "discard" as a generic term to indicate the act of discarding a packet, irrespective of whether the sender is notified of such drops, a drop and irrespective of whether the specific filtering action is logged.
</t>

<t>The
        <t indent="0" pn="section-2.1-2">
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
      "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
    "<bcp14>MAY</bcp14>", and "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP 14 BCP 14 <xref target='RFC2119' /> <xref target='RFC8174' /> target="RFC2119" format="default" sectionFormat="of" derivedContent="RFC2119"/> <xref target="RFC8174" format="default" sectionFormat="of" derivedContent="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.
        </t>
      </section>
      <section title="Applicability Statement">
<t>This numbered="true" toc="include" removeInRFC="false" pn="section-2.2">
        <name slugifiedName="name-applicability-statement">Applicability Statement</name>
        <t indent="0" pn="section-2.2-1">This document provides advice on the filtering of IPv6 packets with EHs at transit routers for traffic not explicitly destined to them, for cases in which such filtering is deemed as necessary.</t>
      </section>
      <section title="Router numbered="true" toc="include" removeInRFC="false" pn="section-2.3">
        <name slugifiedName="name-router-default-behavior-and">Router Default Behavior and Features">
<t>This Features</name>
        <t indent="0" pn="section-2.3-1">This document assumes that nodes comply with the requirements in <xref target="RFC7045"/>. target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>. Namely,
<list style="hanging">
<t>"If
        </t>
        <blockquote pn="section-2.3-2">If a forwarding node discards a packet containing a standard IPv6
   extension header, it MUST <bcp14>MUST</bcp14> be the result of a configurable policy and
   not just the result of a failure to recognise such a header.  This
   means that the discard policy for each standard type of extension
   header MUST <bcp14>MUST</bcp14> be individually configurable.  The default configuration
   SHOULD
   <bcp14>SHOULD</bcp14> allow all standard extension headers."</t>
</list> headers.</blockquote>
        <t indent="0" pn="section-2.3-3">

	  The advice provided in this document is only meant to guide an operator in configuring forwarding devices, devices and is not to be interpreted as advice regarding default configuration settings for network devices. That is, this document provides advice with respect to operational policies, policies but does not change the implementation defaults required by <xref target="RFC7045"/><!--  and <xref target="draft-gont-6man-ipv6-opt-transmit"/>-->. <!--We note that the advice provided in this document is *not* meant to be employed by transit routers for transit traffic, since such devices should not enforce this type of filtering policy on traffic not directed to them. --> target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>.

</t>

<t>We
        <t indent="0" pn="section-2.3-4">We recommend that configuration options are be made available to govern the processing of each IPv6 EH type and each IPv6 option type. Option Type. Such configuration options should include the following possible settings:
<list style="symbols">
<t>Permit
        </t>
        <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-2.3-5">
          <li pn="section-2.3-5.1">Permit this IPv6 EH or IPv6 Option type.</t>
<t>Drop Type.</li>
          <li pn="section-2.3-5.2">Drop packets containing this IPv6 EH or option type.</t>
<t>Reject IPv6 Option Type.</li>
          <li pn="section-2.3-5.3">Reject packets containing this IPv6 EH or option type IPv6 Option Type (where the packet drop is signaled with an ICMPv6 error message).</t>
<t>Rate-limit message).</li>
          <li pn="section-2.3-5.4">Rate-limit traffic containing this IPv6 EH or option type.</t>
<t>Ignore IPv6 Option Type.</li>
          <li pn="section-2.3-5.5">Ignore this IPv6 EH or option type IPv6 Option Type (as if it was not present) present), and process the packet according the rules for the remaining headers. We note that if a packet carries forwarding information (e.g., in an IPv6 Routing Header) Header (RH)), this might be an inappropriate or undesirable action.</t>
</list>
</t>

<t>We action.</li>
        </ul>
        <t indent="0" pn="section-2.3-6">We note that special care needs to be taken when devices log packet drops/rejects. Devices should count the number of packets dropped/rejected, but the logging of drop/reject events should be limited so as to not overburden device resources.</t>

<t>Finally,
        <t indent="0" pn="section-2.3-7">Finally, we note that when discarding packets, it is generally desirable that the sender be signaled of the packet drop, since this is of use for trouble-shooting purposes. However, throughout this document (when recommending that packets be discarded) discarded), we generically refer to the action as "discard" without specifying whether the sender is signaled of the packet drop.</t>
      </section>
    </section>
    <section title="IPv6 anchor="ipv6-extension-headers-discussion" numbered="true" toc="include" removeInRFC="false" pn="section-3">
      <name slugifiedName="name-ipv6-extension-headers">IPv6 Extension Headers" anchor="ipv6-extension-headers-discussion"> Headers</name>
      <section title="General Discussion">
<t>IPv6 <xref target="RFC8200"/> numbered="true" toc="include" removeInRFC="false" pn="section-3.1">
        <name slugifiedName="name-general-discussion">General Discussion</name>
        <t indent="0" pn="section-3.1-1">IPv6 EHs <xref target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/> allow for the extension of the IPv6 protocol. Since both IPv6 EHs and upper-layer protocols share the same namespace ("Next Header" registry/namespace), <xref target="RFC7045"/> target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/> identifies which of the currently assigned Internet Protocol numbers identify IPv6 EHs vs. upper-layer protocols. This document discusses the filtering of packets based on the IPv6 EHs (as specified by <xref target="RFC7045"/>) target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>) they contain. <!-- Filtering of IPv6 packets based on the upper-layer protocol is specified in <xref target="upper-layer"/>--></t>

<t>
<list style="hanging">
<t>
NOTE: <xref target="RFC8200"/>
        </t>
        <t indent="0" pn="section-3.1-2">
<xref target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/> specifies that non-fragmented IPv6 datagrams and IPv6 First-Fragments must contain the entire IPv6 header chain <xref target="RFC7112"/>. target="RFC7112" format="default" sectionFormat="of" derivedContent="RFC7112"/>. Therefore, intermediate systems can enforce the filtering policies discussed in this document, document or resort to simply discarding the offending packets when they fail to comply with include the requirements in entire IPv6 header chain <xref target="RFC8200"/>. target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>. </t>
        <t indent="0" pn="section-3.1-3">
We note that, that in order to implement filtering rules on the fast path, it may be necessary for the filtering device to limit the depth into the packet that can be inspected before giving up. In circumstances where such
      a limitation exists, it is recommended that implementations provide a
      configuration option that specifies whether to discard packets if
      the aforementioned limit is encountered.  Operators may then
      determine
      determine, according to their own circumstances circumstances, how such packets
      will be handled.
</t>
</list>
</t>
<!--
<t>When processing a non-fragmented IPv6 datagram or an IPv6 First-Fragment, the packet must contain the entire IPv6 header chain <xref target="RFC7112"/>. An intermediate system that processes a packet that fails to comply with this requirement should therefore drop the offending packets.
</t>
-->
      </section>
      <section title="General anchor="ipv6-eh-general-implications" numbered="true" toc="include" removeInRFC="false" pn="section-3.2">
        <name slugifiedName="name-general-security-implicatio">General Security Implications" anchor="ipv6-eh-general-implications">
<t>In Implications</name>
        <t indent="0" pn="section-3.2-1">In some device architectures, IPv6 packets that contain IPv6 EHs can cause the corresponding packets to be processed on the slow path, and hence path and, hence, may be leveraged for the purpose of Denial of Service Denial-of-Service (DoS) attacks <xref target="RFC9098"/> <xref target="Cisco-EH"/> <xref target="FW-Benchmark"/>. target="RFC9098" format="default" sectionFormat="of" derivedContent="RFC9098"/> <xref target="Cisco-EH" format="default" sectionFormat="of" derivedContent="Cisco-EH"/> <xref target="FW-Benchmark" format="default" sectionFormat="of" derivedContent="FW-Benchmark"/>.
</t>
<t>Operators
        <t indent="0" pn="section-3.2-2">Operators are urged to consider the IPv6 EH and IPv6 options handling capabilities of their devices as they make deployment decisions in the future.</t>
      </section>
      <section title="Rationale anchor="ipv6-ehs-rationale" numbered="true" toc="include" removeInRFC="false" pn="section-3.3">
        <name slugifiedName="name-rationale-for-our-advice-on">Rationale for Our Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers" anchor="ipv6-ehs-rationale">
<t>
<list style="symbols">
<t>IPv6 Packets Headers</name>
        <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-3.3-1">
          <li pn="section-3.3-1.1">IPv6 packets with IPv6 Extension Headers (or options) that are not expected to traverse transit routers should be dropped.</t>

  <t>IPv6 Packets dropped.</li>
          <li pn="section-3.3-1.2">IPv6 packets with IPv6 Extension Headers (or options) that are only
    expected to traverse transit routers when a specific technology is
    employed,
    employed should be permitted (or dropped) based on the knowledge
    regarding the use of such technology in the transit provider in question
    (i.e.
    (i.e., permit the packets if the technology is employed, or drop them)
    </t>

   <t>IPv6 Packets them).
    </li>
          <li pn="section-3.3-1.3">IPv6 packets with IPv6 Extension Headers (or options) that represent
    a concrete attack vector to network infrastructure devices should be dropped.</t>

  <t>IPv6 dropped.</li>
          <li pn="section-3.3-1.4">IPv6 packets with any other IPv6 Extension headers Headers (or options)
    should be permitted. This is an intentional  trade-off made to
    minimize ossification.</t>
</list>

</t> ossification.</li>
        </ul>
      </section>
      <section title="Summary numbered="true" toc="include" removeInRFC="false" pn="section-3.4">
        <name slugifiedName="name-summary-of-advice-on-the-ha">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers">
<t>This Headers</name>
        <t indent="0" pn="section-3.4-1">This section summarizes the advice provided in <xref target="advice-ehs"/>, target="advice-ehs" format="default" sectionFormat="of" derivedContent="Section 3.5"/>, providing references to the specific sections in which a detailed analysis can be found.</t>

    <texttable title="Summary
        <table anchor="eh-table" align="center" pn="table-1">
          <name slugifiedName="name-summary-of-advice-on-the-han">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers" style="all" anchor="eh-table">
        <ttcol align="center">EH type</ttcol>
        <ttcol align="center">Filtering policy</ttcol>
        <ttcol align="center">Reference</ttcol>
<c>IPv6 Hop-by-Hop Headers</name>
          <thead>
            <tr>
              <th align="center" colspan="1" rowspan="1">EH Type</th>
              <th align="center" colspan="1" rowspan="1">Filtering Policy</th>
              <th align="center" colspan="1" rowspan="1">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="center" colspan="1" rowspan="1">Hop-by-Hop Options (Proto=0)</c><c>Drop Header (Proto=0)</td>
              <td align="center" colspan="1" rowspan="1">Drop or Ignore</c><c><xref target="proto0"/></c>
<c>Routing Ignore</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto0" format="default" sectionFormat="of" derivedContent="Section 3.5.1"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Routing Header for IPv6 (Proto=43)</c><c>Drop (Proto=43)</td>
              <td align="center" colspan="1" rowspan="1">Drop only RHT0 Routing Type 0, Routing Type 1, and RHT1. Routing Type 3. Permit other RH Types</c><c><xref target="proto43"/></c>
<c>Fragment Routing Types</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto43" format="default" sectionFormat="of" derivedContent="Section 3.5.2"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Fragment Header for IPv6 (Proto=44)</c><c>Permit</c><c><xref target="proto44"/></c>
<c>Encapsulating (Proto=44)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto44" format="default" sectionFormat="of" derivedContent="Section 3.5.3"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Encapsulating Security Payload (Proto=50)</c><c>Permit</c><c><xref target="proto50"/></c>
<c>Authentication (Proto=50)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto50" format="default" sectionFormat="of" derivedContent="Section 3.5.4"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Authentication Header (Proto=51)</c><c>Permit</c><c><xref target="proto51"/></c>
<c>Destination (Proto=51)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto51" format="default" sectionFormat="of" derivedContent="Section 3.5.5"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Destination Options for IPv6 (Proto=60)</c><c>Permit</c><c><xref target="proto60"/></c>
<c>Mobility Header(Proto=60)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto60" format="default" sectionFormat="of" derivedContent="Section 3.5.6"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Mobility Header (Proto=135)</c><c>Permit</c><c><xref target="proto135"/></c>
<c>Host (Proto=135)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto135" format="default" sectionFormat="of" derivedContent="Section 3.5.7"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Host Identity Protocol (Proto=139)</c><c>Permit</c><c><xref target="proto139"/></c>
<c>Shim6 Protocol (Proto=140)</c><c>Permit</c><c><xref target="proto140"/></c>
<c>Use (Proto=139)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto139" format="default" sectionFormat="of" derivedContent="Section 3.5.8"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Shim6 Protocol (Proto=140)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto140" format="default" sectionFormat="of" derivedContent="Section 3.5.9"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Use for experimentation and testing (Proto=253 and
         254)</c><c>Drop</c><c><xref target="proto253254"/></c>
    </texttable>

</section>

<section title="Advice
         254)</td>
              <td align="center" colspan="1" rowspan="1">Drop</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="proto253254" format="default" sectionFormat="of" derivedContent="Section 3.5.10"/></td>
            </tr>
          </tbody>
        </table>
      </section>
      <section anchor="advice-ehs" numbered="true" toc="include" removeInRFC="false" pn="section-3.5">
        <name slugifiedName="name-advice-on-the-handling-of-i">Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers" anchor="advice-ehs"> Headers</name>
        <section title="IPv6 anchor="proto0" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1">
          <name slugifiedName="name-ipv6-hop-by-hop-options-pro">IPv6 Hop-by-Hop Options (Protocol Number=0)" anchor="proto0"> Number=0)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1.1">
            <name slugifiedName="name-uses">Uses</name>
            <t indent="0" pn="section-3.5.1.1-1">The Hop-by-Hop (HBH) Options header is used to carry optional information that may be examined by every node along a packet's delivery path. It is expected that nodes will examine the Hop-by-Hop Options header if explicitly configured to do so.</t>

<t>NOTE:
            <aside pn="section-3.5.1.1-2">
              <t indent="0" pn="section-3.5.1.1-2.1">NOTE: A previous revision of the IPv6 core specification, specification <xref target="RFC2460"/>, target="RFC2460" format="default" sectionFormat="of" derivedContent="RFC2460"/> originally required that all nodes examined to examine and processed process the Hop-by-Hop Options header. However, even before the publication of <xref target="RFC8200"/> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>, a number of implementations already provided the option of ignoring this header unless explicitly configured to examine it.
</t>
            </aside>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1.2">
            <name slugifiedName="name-specification">Specification</name>
            <t indent="0" pn="section-3.5.1.2-1">This EH is specified in <xref target="RFC8200"/>. target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>. As of May 2022, the following options have been specified for the Hop-by-Hop Options EH: header:
</t>
<t>
<list style="symbols">
<t>Type
            <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-3.5.1.2-2">
              <li pn="section-3.5.1.2-2.1">Type 0x00: Pad1 <xref target="RFC8200"/></t>
<t>Type target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/></li>
              <li pn="section-3.5.1.2-2.2">Type 0x01: PadN <xref target="RFC8200"/></t>
<t>Type target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/></li>
              <li pn="section-3.5.1.2-2.3">Type 0x05: Router Alert <xref target="RFC2711"/></t>
<t>Type target="RFC2711" format="default" sectionFormat="of" derivedContent="RFC2711"/></li>
              <li pn="section-3.5.1.2-2.4">Type 0x07: CALIPSO <xref target="RFC5570"/></t>
<t>Type target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/></li>
              <li pn="section-3.5.1.2-2.5">Type 0x08: SMF_DPD <xref target="RFC6621"/></t>
<t>Type target="RFC6621" format="default" sectionFormat="of" derivedContent="RFC6621"/></li>
              <li pn="section-3.5.1.2-2.6">Type 0x23: RPL Option <xref target="RFC9008"/></t>
<t>Type target="RFC9008" format="default" sectionFormat="of" derivedContent="RFC9008"/></li>
              <li pn="section-3.5.1.2-2.7">Type 0x26: Quick-Start <xref target="RFC4782"/></t>
<t>Type target="RFC4782" format="default" sectionFormat="of" derivedContent="RFC4782"/></li>
              <li pn="section-3.5.1.2-2.8">Type 0x4D: (Deprecated)</t>
<t>Type (Deprecated)</li>
              <li pn="section-3.5.1.2-2.9">Type 0x63: RPL Option <xref target="RFC6553"/></t>
<t>Type target="RFC6553" format="default" sectionFormat="of" derivedContent="RFC6553"/></li>
              <li pn="section-3.5.1.2-2.10">Type 0x6D: MPL Option <xref target="RFC7731"/></t>
<!-- [fgont] THis one is deprecated... I guess no need to mention it, right? -->
<t>Type target="RFC7731" format="default" sectionFormat="of" derivedContent="RFC7731"/></li>
              <li pn="section-3.5.1.2-2.11">Type 0x8A: Endpoint Identification (Deprecated) <xref target="draft-ietf-nimrod-eid"/></t>
<t>Type target="NIMROD-EID" format="default" sectionFormat="of" derivedContent="NIMROD-EID"/></li>
              <li pn="section-3.5.1.2-2.12">Type 0xC2: Jumbo Payload <xref target="RFC2675"/></t>
<t>Type target="RFC2675" format="default" sectionFormat="of" derivedContent="RFC2675"/></li>
              <li pn="section-3.5.1.2-2.13">Type 0xEE: IPv6 DFF Header <xref target="RFC6971"/></t>

<t>Type target="RFC6971" format="default" sectionFormat="of" derivedContent="RFC6971"/></li>
              <li pn="section-3.5.1.2-2.14">Type 0x1E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.15">Type 0x3E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.16">Type 0x5E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.17">Type 0x7E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.18">Type 0x9E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.19">Type 0xBE: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.20">Type 0xDE: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.1.2-2.21">Type 0xFE: RFC3692-style Experiment <xref target="RFC4727"/></t>
</list></t> target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
            </ul>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1.3">
            <name slugifiedName="name-specific-security-implicati">Specific Security Implications">
<t>Legacy Implications</name>
            <t indent="0" pn="section-3.5.1.3-1">Legacy nodes that process this extension header might be subject to Denial of Service DoS attacks.</t>
<t>NOTE:
            <aside pn="section-3.5.1.3-2">
              <t indent="0" pn="section-3.5.1.3-2.1">NOTE: While <xref target="RFC8200"/> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/> has removed this requirement, the requirement for all nodes to examine and process the Hop-by-Hop Options header, the deployed base may still reflect the classical legacy <xref target="RFC2460" format="default" sectionFormat="of" derivedContent="RFC2460"/> behavior for a while, and hence while; hence, the potential security problems of this EH are still of concern.
</t>
            </aside>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1.4">
            <name slugifiedName="name-operational-and-interoperab">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.1.4-1">Discarding packets containing a Hop-by-Hop Options EH header would break any of the protocols that rely on it for proper functioning. For example, it would break RSVP <xref target="RFC2205"/> target="RFC2205" format="default" sectionFormat="of" derivedContent="RFC2205"/> and multicast deployments, deployments and would cause IPv6 jumbograms to be discarded.</t>
          </section>
          <section title="Advice">
<t>Nodes numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.1.5">
            <name slugifiedName="name-advice">Advice</name>
            <t indent="0" pn="section-3.5.1.5-1">Nodes implementing <xref target="RFC8200"/> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/> would already ignore this extension header unless explicitly required to process it. For legacy (<xref target="RFC2460"/>) nodes, nodes <xref target="RFC2460" format="default" sectionFormat="of" derivedContent="RFC2460"/>, the recommended configuration for the processing of these packets depends on the features and capabilities of the underlying platform, the configuration of the platform, and also the deployment environment of the platform. On platforms that allow the forwarding of packets with IPv6 HBH Options headers on the fast path, we recommend that packets with a IPv6 HBH Options EH headers be forwarded as normal. Otherwise, on platforms in which the processing of packets with a IPv6 HBH Options EH headers is carried out in the slow path, path and an option is provided to rate-limit these packets, we recommend that this option be selected. Finally, when packets containing a IPv6 HBH Options EH headers are processed in the slow-path, slow path and the underlying platform does not have any mitigation options available for attacks based on these packets, we recommend that such platforms discard packets containing IPv6 HBH Options EHs.</t>

<t>Finally, headers.</t>
            <t indent="0" pn="section-3.5.1.5-2">Finally, we note that RPL (Routing the Routing Protocol for Low-Power and Lossy Networks) Networks (RPL) routers <xref target="RFC6550"/> target="RFC6550" format="default" sectionFormat="of" derivedContent="RFC6550"/>  must not discard packets based on the presence of an IPv6 Hop-by-Hop Options EH, header, as this would break the RPL.</t>
          </section>
        </section>
        <section title="Routing anchor="proto43" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2">
          <name slugifiedName="name-routing-header-protocol-num">Routing Header for IPv6 (Protocol Number=43)" anchor="proto43"> Number=43)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2.1">
            <name slugifiedName="name-uses-2">Uses</name>
            <t indent="0" pn="section-3.5.2.1-1">The Routing header Header is used by an IPv6 source to list one or more intermediate nodes to be "visited" on the way to a packet's destination. </t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2.2">
            <name slugifiedName="name-specification-2">Specification</name>
            <t indent="0" pn="section-3.5.2.2-1">This EH is specified in <xref target="RFC8200"/>. <xref target="RFC2460"/> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>. The Routing Type 0 had originally been specified the Routing Header Type 0, which in <xref target="RFC2460" format="default" sectionFormat="of" derivedContent="RFC2460"/> and was later obsoleted by <xref target="RFC5095"/>, and thus target="RFC5095" format="default" sectionFormat="of" derivedContent="RFC5095"/>; thus, it was removed from <xref target="RFC8200"/>.</t>

<t>At target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>.</t>
            <t indent="0" pn="section-3.5.2.2-2">As of May 2022, the following Routing Types have been specified:

<list style="symbols">
<t>Type specified:</t>
            <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-3.5.2.2-3">
              <li pn="section-3.5.2.2-3.1">Type 0: Source Route (DEPRECATED) <xref target="RFC2460"/> <xref target="RFC5095"/></t>
<t>Type target="RFC2460" format="default" sectionFormat="of" derivedContent="RFC2460"/> <xref target="RFC5095" format="default" sectionFormat="of" derivedContent="RFC5095"/></li>
              <li pn="section-3.5.2.2-3.2">Type 1: Nimrod (DEPRECATED)</t>
<t>Type (DEPRECATED)</li>
              <li pn="section-3.5.2.2-3.3">Type 2: Type 2 Routing Header <xref target="RFC6275"/></t>
<t>Type target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/></li>
              <li pn="section-3.5.2.2-3.4">Type 3: RPL Source Route Header <xref target="RFC6554"/></t>
<t>Type target="RFC6554" format="default" sectionFormat="of" derivedContent="RFC6554"/></li>
              <li pn="section-3.5.2.2-3.5">Type 4: Segment Routing Header (SRH) <xref target="RFC8754"/></t>
<t>Types target="RFC8754" format="default" sectionFormat="of" derivedContent="RFC8754"/></li>
              <li pn="section-3.5.2.2-3.6">Types 5-252: Unassigned </t>
<t>Type Unassigned</li>
              <li pn="section-3.5.2.2-3.7">Type 253: RFC3692-style Experiment 1 <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.2.2-3.8">Type 254: RFC3692-style Experiment 2 <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.2.2-3.9">Type 255: Reserved</t>
</list>
</t> Reserved</li>
            </ul>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2.3">
            <name slugifiedName="name-specific-security-implicatio">Specific Security Implications">
<t>The Implications</name>
            <t indent="0" pn="section-3.5.2.3-1">The security implications of RHT0 Routing Headers of Routing Type 0 have been discussed in detail in <xref target="Biondi2007"/> target="Biondi-2007" format="default" sectionFormat="of" derivedContent="Biondi-2007"/> and <xref target="RFC5095"/>. RHT1 target="RFC5095" format="default" sectionFormat="of" derivedContent="RFC5095"/>. Routing Type 1 was never widely implemented. The security implications of RHT2, RHT3, Routing Headers of Routing Type 2, Routing Type 3, and RHT4 Routing Type 4 (SRH) are discussed in <xref target="RFC6275"/>,  <xref target="RFC6554"/>, target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/>,  <xref target="RFC6554" format="default" sectionFormat="of" derivedContent="RFC6554"/>, and <xref target="RFC8754"/>, target="RFC8754" format="default" sectionFormat="of" derivedContent="RFC8754"/>, respectively.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2.4">
            <name slugifiedName="name-operational-and-interoperabi">Operational and Interoperability Impact if Blocked">
<t>Blocking If Blocked</name>
            <t indent="0" pn="section-3.5.2.4-1">Blocking packets containing a RHT0 Routing Headers of Routing Type 0 or RHT1 Routing Type 1 has no operational implications, since both have been deprecated. Blocking packets with a RHT2 containing Routing Headers of Routing Type 2 would break Mobile IPv6. Packets with a RHT3 containing Routing Headers of Routing Type 3 may be safely blocked at RPL domain boundaries, since RHT3 such headers are employed within a single RPL domain. Blocking packets with a RHT4 containing Routing Headers of Routing Type 4 (SRH) will break Segment Routing (SR) deployments, deployments if the filtering policy is enforced on packets being forwarded within an SR domain.</t>

<!--<t>However, blocking packets employing other routing header types will break the protocols that rely on them.</t> -->
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.2.5">
            <name slugifiedName="name-advice-2">Advice</name>
            <t indent="0" pn="section-3.5.2.5-1">Intermediate systems should discard packets containing a RHT0, RHT1, Routing Headers of Routing Type 0, Routing Type 1, or RHT3. Routing Type 3. Other routing header types Routing Types should be permitted, as required by <xref target="RFC7045"/>.</t> target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>.</t>
          </section>
        </section>
        <section title="Fragment anchor="proto44" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3">
          <name slugifiedName="name-fragment-header-protocol-nu">Fragment Header for IPv6 (Protocol Number=44)" anchor="proto44"> Number=44)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3.1">
            <name slugifiedName="name-uses-3">Uses</name>
            <t indent="0" pn="section-3.5.3.1-1">This EH provides the fragmentation and reassembly functionality for IPv6.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3.2">
            <name slugifiedName="name-specification-3">Specification</name>
            <t indent="0" pn="section-3.5.3.2-1">This EH is specified in <xref target="RFC8200"/>.</t> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3.3">
            <name slugifiedName="name-specific-security-implication">Specific Security Implications">
<t>The Implications</name>
            <t indent="0" pn="section-3.5.3.3-1">The security implications of the Fragment Header range from Denial of Service DoS attacks (e.g. (e.g., based on flooding a target with IPv6 fragments) to information leakage attacks <xref target="RFC7739"/>.</t> target="RFC7739" format="default" sectionFormat="of" derivedContent="RFC7739"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3.4">
            <name slugifiedName="name-operational-and-interoperabil">Operational and Interoperability Impact if Blocked">
<t>Blocking If Blocked</name>
            <t indent="0" pn="section-3.5.3.4-1">Blocking packets that contain a Fragment Header will break any protocol that may rely on fragmentation (e.g., the DNS <xref target="RFC1034"/>). target="RFC1034" format="default" sectionFormat="of" derivedContent="RFC1034"/>). However, IP fragmentation is known to introduce fragility to Internet communication <xref target="RFC8900"/>.</t> target="RFC8900" format="default" sectionFormat="of" derivedContent="RFC8900"/>.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.3.5">
            <name slugifiedName="name-advice-3">Advice</name>
            <t indent="0" pn="section-3.5.3.5-1">Intermediate systems should permit packets that contain a Fragment Header.</t>
          </section>
        </section>
        <section title="Encapsulating anchor="proto50" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4">
          <name slugifiedName="name-encapsulating-security-payl">Encapsulating Security Payload (Protocol Number=50)" anchor="proto50"> Number=50)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4.1">
            <name slugifiedName="name-uses-4">Uses</name>
            <t indent="0" pn="section-3.5.4.1-1">This EH is employed for the IPsec suite <xref target="RFC4303"/>.</t> target="RFC4303" format="default" sectionFormat="of" derivedContent="RFC4303"/>.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4.2">
            <name slugifiedName="name-specification-4">Specification</name>
            <t indent="0" pn="section-3.5.4.2-1">This EH is specified in <xref target="RFC4303"/>.</t> target="RFC4303" format="default" sectionFormat="of" derivedContent="RFC4303"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4.3">
            <name slugifiedName="name-specific-security-implications">Specific Security Implications">
<t>Besides Implications</name>
            <t indent="0" pn="section-3.5.4.3-1">Besides the general implications of IPv6 EHs, this EH could be employed to potentially perform a DoS attack at the destination system by wasting CPU resources in validating the contents of the packet.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4.4">
            <name slugifiedName="name-operational-and-interoperabili">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.4.4-1">Discarding packets that employ this EH would break IPsec deployments.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.4.5">
            <name slugifiedName="name-advice-4">Advice</name>
            <t indent="0" pn="section-3.5.4.5-1">Intermediate systems should permit packets containing the Encapsulating Security Payload EH.</t>
          </section>
        </section>
        <section title="Authentication anchor="proto51" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5">
          <name slugifiedName="name-authentication-header-proto">Authentication Header (Protocol Number=51)" anchor="proto51"> Number=51)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5.1">
            <name slugifiedName="name-uses-5">Uses</name>
            <t indent="0" pn="section-3.5.5.1-1">The Authentication Header can be employed for to provide authentication services in
   IPv4 and IPv6.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5.2">
            <name slugifiedName="name-specification-5">Specification</name>
            <t indent="0" pn="section-3.5.5.2-1">This EH is specified in <xref target="RFC4302"/>.</t> target="RFC4302" format="default" sectionFormat="of" derivedContent="RFC4302"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5.3">
            <name slugifiedName="name-specific-security-implications-2">Specific Security Implications">
<t>Besides Implications</name>
            <t indent="0" pn="section-3.5.5.3-1">Besides the general implications of IPv6 EHs, this EH could be employed to potentially perform a DoS attack at the destination system by wasting CPU resources in validating the contents of the packet.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5.4">
            <name slugifiedName="name-operational-and-interoperabilit">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.5.4-1">Discarding packets that employ this EH would break IPsec deployments.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.5.5">
            <name slugifiedName="name-advice-5">Advice</name>
            <t indent="0" pn="section-3.5.5.5-1">Intermediate systems should permit packets containing an Authentication Header.</t>
          </section>
        </section>
        <section title="Destination anchor="proto60" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6">
          <name slugifiedName="name-destination-options-protoco">Destination Options for IPv6 (Protocol Number=60)" anchor="proto60"> Number=60)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6.1">
            <name slugifiedName="name-uses-6">Uses</name>
            <t indent="0" pn="section-3.5.6.1-1">The Destination Options (DO) header is used to carry optional information that needs be examined only by a packet's destination node(s).</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6.2">
            <name slugifiedName="name-specification-6">Specification</name>
            <t indent="0" pn="section-3.5.6.2-1">This EH is specified in <xref target="RFC8200"/>. target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>. As of May 2022, the following options have been specified for this EH:

<list style="symbols">
<t>Type
</t>
            <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-3.5.6.2-2">
              <li pn="section-3.5.6.2-2.1">Type 0x00: Pad1 <xref target="RFC8200"/></t>
<t>Type target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/></li>
              <li pn="section-3.5.6.2-2.2">Type 0x01: PadN <xref target="RFC8200"/></t>
<t>Type target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/></li>
              <li pn="section-3.5.6.2-2.3">Type 0x04: Tunnel Encapsulation Limit <xref target="RFC2473"/></t>
<t>Type target="RFC2473" format="default" sectionFormat="of" derivedContent="RFC2473"/></li>
              <li pn="section-3.5.6.2-2.4">Type 0x0F: IPv6 Performance and Diagnostic Metrics (PDM) <xref target="RFC8250"/></t>
<t>Type target="RFC8250" format="default" sectionFormat="of" derivedContent="RFC8250"/></li>
              <li pn="section-3.5.6.2-2.5">Type 0x4D: (Deprecated)</t>

<t>Type (Deprecated)</li>
              <li pn="section-3.5.6.2-2.6">Type 0xC9: Home Address <xref target="RFC6275"/></t>
<t>Type target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/></li>
              <li pn="section-3.5.6.2-2.7">Type 0x8A: Endpoint Identification (Deprecated) <xref target="draft-ietf-nimrod-eid"/></t>

<t>Type target="NIMROD-EID" format="default" sectionFormat="of" derivedContent="NIMROD-EID"/></li>
              <li pn="section-3.5.6.2-2.8">Type 0x8B: ILNP Nonce <xref target="RFC6744"/></t>
<t>Type target="RFC6744" format="default" sectionFormat="of" derivedContent="RFC6744"/></li>
              <li pn="section-3.5.6.2-2.9">Type 0x8C: Line-Identification Option <xref target="RFC6788"/></t>
<t>Type target="RFC6788" format="default" sectionFormat="of" derivedContent="RFC6788"/></li>
              <li pn="section-3.5.6.2-2.10">Type 0x1E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.11">Type 0x3E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.12">Type 0x5E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.13">Type 0x7E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.14">Type 0x9E: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.15">Type 0xBE: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.16">Type 0xDE: RFC3692-style Experiment <xref target="RFC4727"/></t>
<t>Type target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
              <li pn="section-3.5.6.2-2.17">Type 0xFE: RFC3692-style Experiment <xref target="RFC4727"/></t>
</list>
</t> target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/></li>
            </ul>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6.3">
            <name slugifiedName="name-specific-security-implications-3">Specific Security Implications">
<t>No Implications</name>
            <t indent="0" pn="section-3.5.6.3-1">No security implications are known, other than the general security implications of IPv6 EHs. For a discussion of possible security implications of specific options specified for the DO header, please see the <xref target="opt-filtering"/>.</t> target="opt-filtering" format="default" sectionFormat="of" derivedContent="Section 4.4"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6.4">
            <name slugifiedName="name-operational-and-interoperability">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.6.4-1">Discarding packets that contain a Destination Options header would break protocols that rely on this EH type for conveying information, including protocols such information (such as ILNP the Identifier-Locator Network Protocol (ILNP) <xref target="RFC6740"/> target="RFC6740" format="default" sectionFormat="of" derivedContent="RFC6740"/> and Mobile IPv6 <xref target="RFC6275"/>, and target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/>), as well as IPv6 tunnels that employ the Tunnel Encapsulation Limit option.</t> option <xref target="RFC2473" format="default" sectionFormat="of" derivedContent="RFC2473"/>.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.6.5">
            <name slugifiedName="name-advice-6">Advice</name>
            <t indent="0" pn="section-3.5.6.5-1">Intermediate systems should permit packets that contain a Destination Options Header.</t> header.</t>
          </section>
        </section>
        <section title="Mobility anchor="proto135" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7">
          <name slugifiedName="name-mobility-header-protocol-nu">Mobility Header (Protocol Number=135)" anchor="proto135"> Number=135)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7.1">
            <name slugifiedName="name-uses-7">Uses</name>
            <t indent="0" pn="section-3.5.7.1-1">The Mobility Header is an EH used by mobile nodes, correspondent nodes, and home agents in all messaging related to the creation and management of bindings in Mobile IPv6.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7.2">
            <name slugifiedName="name-specification-7">Specification</name>
            <t indent="0" pn="section-3.5.7.2-1">This EH is specified in <xref target="RFC6275"/>.</t> target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7.3">
            <name slugifiedName="name-specific-security-implications-4">Specific Security Implications">
<t>A Implications</name>
            <t indent="0" pn="section-3.5.7.3-1">A thorough security assessment of the security implications of the Mobility Header and related mechanisms can be found in Section 15 of <xref target="RFC6275"/>.</t> target="RFC6275" sectionFormat="of" section="15" format="default" derivedLink="https://rfc-editor.org/rfc/rfc6275#section-15" derivedContent="RFC6275"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7.4">
            <name slugifiedName="name-operational-and-interoperability-">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.7.4-1">Discarding packets containing this EH would break Mobile IPv6.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.7.5">
            <name slugifiedName="name-advice-7">Advice</name>
            <t indent="0" pn="section-3.5.7.5-1">Intermediate systems should permit packets containing this EH.</t> that contain a Mobility Header.</t>
          </section>
        </section>
        <section title="Host anchor="proto139" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8">
          <name slugifiedName="name-host-identity-protocol-prot">Host Identity Protocol (Protocol Number=139)" anchor="proto139"> Number=139)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8.1">
            <name slugifiedName="name-uses-8">Uses</name>
            <t indent="0" pn="section-3.5.8.1-1">This EH is employed with the Host Identity Protocol (HIP), which is a protocol that allows consenting hosts to securely establish and maintain shared IP-layer state, allowing the separation of the identifier and locator roles of IP addresses, thereby enabling continuity of communications across IP address changes.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8.2">
            <name slugifiedName="name-specification-8">Specification</name>
            <t indent="0" pn="section-3.5.8.2-1">This EH is specified in <xref target="RFC7401"/>.</t> target="RFC7401" format="default" sectionFormat="of" derivedContent="RFC7401"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8.3">
            <name slugifiedName="name-specific-security-implications-5">Specific Security Implications">
<t>The Implications</name>
            <t indent="0" pn="section-3.5.8.3-1">The security implications of the HIP header are discussed in detail in Section 8 of <xref target="RFC6275"/>.</t> target="RFC7401" sectionFormat="of" section="8" format="default" derivedLink="https://rfc-editor.org/rfc/rfc7401#section-8" derivedContent="RFC7401"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8.4">
            <name slugifiedName="name-operational-and-interoperability-i">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.8.4-1">Discarding packets that contain the Host Identity Protocol a HIP header would break HIP deployments.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.8.5">
            <name slugifiedName="name-advice-8">Advice</name>
            <t indent="0" pn="section-3.5.8.5-1">Intermediate systems should permit packets that contain a Host Identity Protocol EH.</t> HIP header.</t>
          </section>
        </section>
        <section title="Shim6 anchor="proto140" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9">
          <name slugifiedName="name-shim6-protocol-protocol-num">Shim6 Protocol (Protocol Number=140)" anchor="proto140"> Number=140)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9.1">
            <name slugifiedName="name-uses-9">Uses</name>
            <t indent="0" pn="section-3.5.9.1-1">This EH is employed by the Shim6 protocol <xref target="RFC5533"/> Protocol.</t> target="RFC5533" format="default" sectionFormat="of" derivedContent="RFC5533"/>.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9.2">
            <name slugifiedName="name-specification-9">Specification</name>
            <t indent="0" pn="section-3.5.9.2-1">This EH is specified in <xref target="RFC5533"/>.</t> target="RFC5533" format="default" sectionFormat="of" derivedContent="RFC5533"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9.3">
            <name slugifiedName="name-specific-security-implications-6">Specific Security Implications">
<t>The Implications</name>
            <t indent="0" pn="section-3.5.9.3-1">The specific security implications are discussed in detail in Section 16 of <xref target="RFC5533"/>.</t> target="RFC5533" sectionFormat="of" section="16" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5533#section-16" derivedContent="RFC5533"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9.4">
            <name slugifiedName="name-operational-and-interoperability-im">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-3.5.9.4-1">Discarding packets that contain this EH will break Shim6.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.9.5">
            <name slugifiedName="name-advice-9">Advice</name>
            <t indent="0" pn="section-3.5.9.5-1">Intermediate systems should permit packets containing this EH.</t>
          </section>
        </section>
        <section title="Use anchor="proto253254" numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10">
          <name slugifiedName="name-use-for-experimentation-and">Use for experimentation Experimentation and testing Testing (Protocol Numbers=253 and 254)" anchor="proto253254"> 254)</name>
          <section title="Uses">
<t>These numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10.1">
            <name slugifiedName="name-uses-10">Uses</name>
            <t indent="0" pn="section-3.5.10.1-1">These IPv6 EHs are employed for performing RFC3692-Style RFC3692-style experiments (see <xref target="RFC3692"/> target="RFC3692" format="default" sectionFormat="of" derivedContent="RFC3692"/> for details).</t>
          </section>
          <section title="Specification">
<t>These numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10.2">
            <name slugifiedName="name-specification-10">Specification</name>
            <t indent="0" pn="section-3.5.10.2-1">These EHs are specified in <xref target="RFC3692"/> and <xref target="RFC4727"/>.</t>
</section>

<section title="Specific target="RFC3692" format="default" sectionFormat="of" derivedContent="RFC3692"/> and <xref target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/>.</t>
          </section>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10.3">
            <name slugifiedName="name-specific-security-implications-7">Specific Security Implications">
<t>The Implications</name>
            <t indent="0" pn="section-3.5.10.3-1">The security implications of these EHs will depend on their specific use.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10.4">
            <name slugifiedName="name-operational-and-interoperability-im-2">Operational and Interoperability Impact if Blocked">
<t>For If Blocked</name>
            <t indent="0" pn="section-3.5.10.4-1">For obvious reasons, discarding packets that contain these EHs limits the ability to perform legitimate experiments across IPv6 routers.
</t>
          </section>
          <section title="Advice">
<t>Operators numbered="true" toc="exclude" removeInRFC="false" pn="section-3.5.10.5">
            <name slugifiedName="name-advice-10">Advice</name>
            <t indent="0" pn="section-3.5.10.5-1">Operators should determine determine, according to their own circumstances circumstances, whether to discard packets containing these EHs.</t>
<!--
<t>Intermediate systems should discard packets containing these EHs. Only in specific scenarios in which RFC3692-Style experiments are to be performed should these EHs be permitted.</t> -->
          </section>
        </section>
      </section>
      <section title="Advice anchor="unknown-headers" numbered="true" toc="include" removeInRFC="false" pn="section-3.6">
        <name slugifiedName="name-advice-on-the-handling-of-p">Advice on the Handling of Packets with Unknown IPv6 Extension Headers" anchor="unknown-headers">
<t>We Headers</name>
        <t indent="0" pn="section-3.6-1">We refer to IPv6 EHs that have not been assigned an Internet Protocol Number number by IANA (and marked as such) in <xref target="IANA-PROTOCOLS"/> target="IANA-PROTOCOLS" format="default" sectionFormat="of" derivedContent="IANA-PROTOCOLS"/> as "unknown IPv6 extension headers" Extension Headers" ("unknown IPv6 EHs").
</t>
        <section title="Uses">
<t>New numbered="true" toc="exclude" removeInRFC="false" pn="section-3.6.1">
          <name slugifiedName="name-uses-11">Uses</name>
          <t indent="0" pn="section-3.6.1-1">New IPv6 EHs may be specified as part of future extensions to the IPv6 protocol.
</t>

<t>Since
          <t indent="0" pn="section-3.6.1-2">Since IPv6 EHs and Upper-layer upper-layer protocols employ the same namespace, it is impossible to tell whether an unknown "Internet Internet Protocol Number" number is being employed for an IPv6 EH or an Upper-Layer upper-layer protocol.
</t>
        </section>
        <section title="Specification">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-3.6.2">
          <name slugifiedName="name-specification-11">Specification</name>
          <t indent="0" pn="section-3.6.2-1">The processing of unknown IPv6 EHs is specified in <xref target="RFC7045"/>.</t> target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>.</t>
        </section>
        <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-3.6.3">
          <name slugifiedName="name-specific-security-implications-8">Specific Security Implications">
<t>For Implications</name>
          <t indent="0" pn="section-3.6.3-1">For obvious reasons, it is impossible to determine specific security implications of unknown IPv6 EHs.</t>
        </section>
        <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-3.6.4">
          <name slugifiedName="name-operational-and-interoperability-im-3">Operational and Interoperability Impact if Blocked">
<t>As If Blocked</name>
          <t indent="0" pn="section-3.6.4-1">As noted in <xref target="RFC7045"/>, target="RFC7045" format="default" sectionFormat="of" derivedContent="RFC7045"/>, discarding unknown IPv6 EHs may slow down the deployment of new IPv6 EHs and transport protocols. The corresponding IANA registry (<xref target="IANA-PROTOCOLS"/>) registry, which is <xref target="IANA-PROTOCOLS" format="default" sectionFormat="of" derivedContent="IANA-PROTOCOLS"/>, should be monitored such that filtering rules are updated as new IPv6 EHs are standardized.</t>

<t>We
          <t indent="0" pn="section-3.6.4-2">We note that since IPv6 EHs and upper-layer protocols share the same numbering space, discarding unknown IPv6 EHs may result in packets encapsulating unknown upper-layer protocols being discarded.
</t>
        </section>
        <section title="Advice">
<t>Operators numbered="true" toc="exclude" removeInRFC="false" pn="section-3.6.5">
          <name slugifiedName="name-advice-11">Advice</name>
          <t indent="0" pn="section-3.6.5-1">Operators should determine determine, according to their own circumstances circumstances, whether to discard packets containing unknown IPv6 EHs.</t>
        </section>
      </section>
    </section>
    <section title="IPv6 Options" anchor="ipv6-options-discussion">
<section title="General Discussion" anchor="ipv6-options-general-discussion">
<t>The anchor="ipv6-options-discussion" numbered="true" toc="include" removeInRFC="false" pn="section-4">
      <name slugifiedName="name-ipv6-options">IPv6 Options</name>
      <section anchor="ipv6-options-general-discussion" numbered="true" toc="include" removeInRFC="false" pn="section-4.1">
        <name slugifiedName="name-general-discussion-2">General Discussion</name>
        <t indent="0" pn="section-4.1-1">The following subsections describe specific security implications of different IPv6 options, options and provide advice regarding filtering packets that contain such options.
</t>
      </section>
      <section title="General anchor="ipv6-options-general-implications" numbered="true" toc="include" removeInRFC="false" pn="section-4.2">
        <name slugifiedName="name-general-security-implication">General Security Implications of IPv6 Options" anchor="ipv6-options-general-implications">
<t>The Options</name>
        <t indent="0" pn="section-4.2-1">The general security implications of IPv6 options are closely related to those discussed in <xref target="ipv6-eh-general-implications"/> target="ipv6-eh-general-implications" format="default" sectionFormat="of" derivedContent="Section 3.2"/> for IPv6 EHs. Essentially, packets that contain IPv6 options might need to be processed by an IPv6 router's general-purpose CPU,and hence CPU and, hence, could present a DDoS Distributed Denial-of-Service (DDoS) risk to that router's general-purpose CPU (and thus to the router itself). For some architectures, a possible mitigation would be to rate-limit the packets that are to be processed by the general-purpose CPU (see e.g. (see, e.g., <xref target="Cisco-EH"/>).</t> target="Cisco-EH" format="default" sectionFormat="of" derivedContent="Cisco-EH"/>).</t>
      </section>
      <section title="Summary numbered="true" toc="include" removeInRFC="false" pn="section-4.3">
        <name slugifiedName="name-summary-of-advice-on-the-hand">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 Extension Headers">
<t>This Options</name>
        <t indent="0" pn="section-4.3-1">This section summarizes the advice provided in <xref target="advice-ehs"/>, providing target="opt-filtering" format="default" sectionFormat="of" derivedContent="Section 4.4"/>, and it includes references to the specific sections in which a detailed analysis can be found.</t>

    <texttable title="Summary
        <table anchor="option-table" align="center" pn="table-2">
          <name slugifiedName="name-summary-of-advice-on-the-handl">Summary of Advice on the Handling of IPv6 Packets with Specific IPv6 options" style="all" anchor="option-table">
        <ttcol align="center">Option</ttcol>
        <ttcol align="center">Filtering policy</ttcol>
        <ttcol align="center">Reference</ttcol>
<c>Pad1 (Type=0x00)</c><c>Permit</c><c><xref target="x00"/></c>
<c>PadN (Type=0x01)</c><c>Permit</c><c><xref target="x01"/></c>
<c>Tunnel Options</name>
          <thead>
            <tr>
              <th align="center" colspan="1" rowspan="1">Option</th>
              <th align="center" colspan="1" rowspan="1">Filtering Policy</th>
              <th align="center" colspan="1" rowspan="1">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="center" colspan="1" rowspan="1">Pad1 (Type=0x00)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x00" format="default" sectionFormat="of" derivedContent="Section 4.4.1"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">PadN (Type=0x01)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x01" format="default" sectionFormat="of" derivedContent="Section 4.4.2"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Tunnel Encapsulation Limit (Type=0x04)</c><c>Permit</c><c><xref target="x04"/></c>
<c>Router (Type=0x04)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x04" format="default" sectionFormat="of" derivedContent="Section 4.4.3"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Router Alert (Type=0x05)</c><c>Permit (Type=0x05)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="x05"/></c>
<c>CALIPSO (Type=0x07)</c><c>Permit functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x05" format="default" sectionFormat="of" derivedContent="Section 4.4.4"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">CALIPSO (Type=0x07)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="x07"/></c>
<c>SMF_DPD (Type=0x08)</c><c>Permit functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x07" format="default" sectionFormat="of" derivedContent="Section 4.4.5"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">SMF_DPD (Type=0x08)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="x08"/></c>
<c>PDM functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x08" format="default" sectionFormat="of" derivedContent="Section 4.4.6"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">PDM Option (Type=0x0F)</c><c>Permit</c><c><xref target="x0F"/></c>
<c>RPL (Type=0x0F)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x0F" format="default" sectionFormat="of" derivedContent="Section 4.4.7"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">RPL Option (Type=0x23)</c><c>Permit</c><c><xref target="x23"/></c>
<c>Quick-Start (Type=0x26)</c><c>Permit</c><c><xref target="x26"/></c>
<c>Deprecated (Type=0x4D)</c><c>Drop</c><c><xref target="x4D"/></c>
<c>MPL (Type=0x23)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x23" format="default" sectionFormat="of" derivedContent="Section 4.4.8"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Quick-Start (Type=0x26)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x26" format="default" sectionFormat="of" derivedContent="Section 4.4.9"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Deprecated (Type=0x4D)</td>
              <td align="center" colspan="1" rowspan="1">Drop</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x4D" format="default" sectionFormat="of" derivedContent="Section 4.4.10"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">MPL Option (Type=0x6D)</c><c>Permit</c><c><xref target="x6D"/></c>
<c>Jumbo (Type=0x6D)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x6D" format="default" sectionFormat="of" derivedContent="Section 4.4.12"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Jumbo Payload (Type=0C2)</c><c>Permit (Type=0xC2)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="xC2"/></c>
<c>RPL functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="xC2" format="default" sectionFormat="of" derivedContent="Section 4.4.16"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">RPL Option (Type=0x63)</c><c>Drop in non-RPL routers</c><c><xref target="x63"/></c>
<c>Endpoint (Type=0x63)</td>
              <td align="center" colspan="1" rowspan="1">Drop</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x63" format="default" sectionFormat="of" derivedContent="Section 4.4.11"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Endpoint Identification (Type=0x8A)</c><c>Drop</c><c><xref target="x8A"/></c>
<c>ILNP (Type=0x8A)</td>
              <td align="center" colspan="1" rowspan="1">Drop</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x8A" format="default" sectionFormat="of" derivedContent="Section 4.4.13"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">ILNP Nonce (Type=0x8B)</c><c>Permit</c><c><xref target="x8B"/></c>
<c>Line-Identification (Type=0x8B)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x8B" format="default" sectionFormat="of" derivedContent="Section 4.4.14"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Line-Identification Option (Type=0x8C)</c><c>Drop</c><c><xref target="x8C"/></c>
<c>Home (Type=0x8C)</td>
              <td align="center" colspan="1" rowspan="1">Drop</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x8C" format="default" sectionFormat="of" derivedContent="Section 4.4.15"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">Home Address (Type=0xC9)</c><c>Permit</c><c><xref target="xC9"/></c>
<c>IP_DFF (Type=0xEE)</c><c>Permit (Type=0xC9)</td>
              <td align="center" colspan="1" rowspan="1">Permit</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="xC9" format="default" sectionFormat="of" derivedContent="Section 4.4.17"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">IP_DFF (Type=0xEE)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="xEE"/></c>
<c>RFC3692-style functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="xEE" format="default" sectionFormat="of" derivedContent="Section 4.4.18"/></td>
            </tr>
            <tr>
              <td align="center" colspan="1" rowspan="1">RFC3692-style Experiment (Types = 0x1E, 0x3E, 0x5E, 0x7E, 0x9E, 0xBE, 0xDE, 0xFE)</c><c>Permit 0xFE)</td>
              <td align="center" colspan="1" rowspan="1">Permit based on needed functionality</c><c><xref target="x1E"/></c>

    </texttable>

</section>

<section title="Advice functionality</td>
              <td align="center" colspan="1" rowspan="1">
                <xref target="x1E" format="default" sectionFormat="of" derivedContent="Section 4.4.19"/></td>
            </tr>
          </tbody>
        </table>
      </section>
      <section anchor="opt-filtering" numbered="true" toc="include" removeInRFC="false" pn="section-4.4">
        <name slugifiedName="name-advice-on-the-handling-of-pa">Advice on the Handling of Packets with Specific IPv6 Options" anchor="opt-filtering">
<t>The Options</name>
        <t indent="0" pn="section-4.4-1">The following subsections contain a description of each of the IPv6 options that have so far been specified, a summary of the security implications of each of such options, a discussion of possible
    interoperability implications if packets containing such options are
    discarded, and specific advice regarding whether packets containing these options should be permitted.</t>
        <section title="Pad1 (Type=0x00)"  anchor="x00">
<section title="Uses">
<t>This anchor="x00" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1">
          <name slugifiedName="name-pad1-type0x00">Pad1 (Type=0x00)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1.1">
            <name slugifiedName="name-uses-12">Uses</name>
            <t indent="0" pn="section-4.4.1.1-1">This option is used when necessary to align subsequent options and to pad out the containing header to a multiple of 8 octets in length.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1.2">
            <name slugifiedName="name-specification-12">Specification</name>
            <t indent="0" pn="section-4.4.1.2-1">This option is specified in <xref target="RFC8200"/>.</t> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1.3">
            <name slugifiedName="name-specific-security-implications-9">Specific Security Implications">
<t>None.</t> Implications</name>
            <t indent="0" pn="section-4.4.1.3-1">None.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1.4">
            <name slugifiedName="name-operational-and-interoperability-im-4">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.1.4-1">Discarding packets that contain this option would potentially break any protocol that relies on IPv6 options.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.1.5">
            <name slugifiedName="name-advice-12">Advice</name>
            <t indent="0" pn="section-4.4.1.5-1">Intermediate systems should not discard packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="PadN (Type=0x01)" anchor="x01">
<section title="Uses">
<t>This anchor="x01" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2">
          <name slugifiedName="name-padn-type0x01">PadN (Type=0x01)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2.1">
            <name slugifiedName="name-uses-13">Uses</name>
            <t indent="0" pn="section-4.4.2.1-1">This option is used when necessary to align subsequent options and to pad out the containing header to a multiple of 8 octets in length.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2.2">
            <name slugifiedName="name-specification-13">Specification</name>
            <t indent="0" pn="section-4.4.2.2-1">This option is specified in <xref target="RFC8200"/>.</t> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2.3">
            <name slugifiedName="name-specific-security-implications-10">Specific Security Implications">
<t>Because Implications</name>
            <t indent="0" pn="section-4.4.2.3-1">Because of the possible size of this option, it could be leveraged as a large-bandwidth covert channel.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2.4">
            <name slugifiedName="name-operational-and-interoperability-im-5">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.2.4-1">Discarding packets that contain this option would potentially break any protocol that relies on IPv6 options.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.2.5">
            <name slugifiedName="name-advice-13">Advice</name>
            <t indent="0" pn="section-4.4.2.5-1">Intermediate systems should not discard IPv6 packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="Tunnel anchor="x04" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3">
          <name slugifiedName="name-tunnel-encapsulation-limit-">Tunnel Encapsulation Limit (Type=0x04)"  anchor="x04"> (Type=0x04)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3.1">
            <name slugifiedName="name-uses-14">Uses</name>
            <t indent="0" pn="section-4.4.3.1-1">The Tunnel Encapsulation Limit option can be employed to specify how many further levels of nesting the packet is permitted to undergo.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3.2">
            <name slugifiedName="name-specification-14">Specification</name>
            <t indent="0" pn="section-4.4.3.2-1">This option is specified in <xref target="RFC2473"/>.</t> target="RFC2473" format="default" sectionFormat="of" derivedContent="RFC2473"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3.3">
            <name slugifiedName="name-specific-security-implications-11">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.3.3-1">These are discussed in <xref target="RFC2473"/>.</t> target="RFC2473" format="default" sectionFormat="of" derivedContent="RFC2473"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3.4">
            <name slugifiedName="name-operational-and-interoperability-im-6">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.3.4-1">Discarding packets based on the presence of this option could result in tunnel traffic being discarded.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.3.5">
            <name slugifiedName="name-advice-14">Advice</name>
            <t indent="0" pn="section-4.4.3.5-1">Intermediate systems should not discard packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="Router anchor="x05" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4">
          <name slugifiedName="name-router-alert-type0x05">Router Alert (Type=0x05)" anchor="x05"> (Type=0x05)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4.1">
            <name slugifiedName="name-uses-15">Uses</name>
            <t indent="0" pn="section-4.4.4.1-1">The Router Alert option <xref target="RFC2711"/> target="RFC2711" format="default" sectionFormat="of" derivedContent="RFC2711"/> is employed by a number of protocols, including the Resource reSerVation Protocol (RSVP) <xref target="RFC2205"/>, target="RFC2205" format="default" sectionFormat="of" derivedContent="RFC2205"/>, Multicast Listener Discovery (MLD) <xref target="RFC2710"/> <xref target="RFC3810"/>, target="RFC2710" format="default" sectionFormat="of" derivedContent="RFC2710"/> <xref target="RFC3810" format="default" sectionFormat="of" derivedContent="RFC3810"/>, Multicast Router Discovery (MRD) <xref target="RFC4286"/>, target="RFC4286" format="default" sectionFormat="of" derivedContent="RFC4286"/>, and General Internet Signaling Transport (GIST) <xref target="RFC5971"/>. target="RFC5971" format="default" sectionFormat="of" derivedContent="RFC5971"/>. Its usage is discussed in detail in <xref target="RFC6398"/>. target="RFC6398" format="default" sectionFormat="of" derivedContent="RFC6398"/>.
</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4.2">
            <name slugifiedName="name-specification-15">Specification</name>
            <t indent="0" pn="section-4.4.4.2-1">This option is specified in <xref target="RFC2711"/>.</t> target="RFC2711" format="default" sectionFormat="of" derivedContent="RFC2711"/>.</t>
          </section>
          <section title="Specific anchor="ra-usage" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4.3">
            <name slugifiedName="name-specific-security-implications-12">Specific Security Implications" anchor="ra-usage">
<t>Since Implications</name>
            <t indent="0" pn="section-4.4.4.3-1">Since this option causes the contents of the packet to be inspected by the handling device, this option could be leveraged for performing DoS attacks. The security implications of the Router Alert option are discussed in detail in <xref target="RFC6398"/>.</t> target="RFC6398" format="default" sectionFormat="of" derivedContent="RFC6398"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4.4">
            <name slugifiedName="name-operational-and-interoperability-im-7">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.4.4-1">Discarding packets that contain this option would break any protocols that rely on them, such as RSVP and multicast deployments. Please see <xref target="ra-usage"/> target="ra-usage" format="default" sectionFormat="of" derivedContent="Section 4.4.4.3"/> for further details.</t>
          </section>
          <section title="Advice">
<t>Packets numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.4.5">
            <name slugifiedName="name-advice-15">Advice</name>
            <t indent="0" pn="section-4.4.4.5-1">Packets containing this option should be permitted in environments where support for RSVP, multicast routing, or similar protocols is desired.</t> required.</t>
          </section>
        </section>
        <section title="CALIPSO (Type=0x07)"  anchor="x07">
<section title="Uses">
<t>This anchor="x07" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5">
          <name slugifiedName="name-calipso-type0x07">CALIPSO (Type=0x07)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5.1">
            <name slugifiedName="name-uses-16">Uses</name>
            <t indent="0" pn="section-4.4.5.1-1">This option is used for encoding explicit packet Sensitivity Labels on IPv6 packets.  It is intended for use only within Multi-Level Secure (MLS) networking environments that are both trusted and trustworthy.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5.2">
            <name slugifiedName="name-specification-16">Specification</name>
            <t indent="0" pn="section-4.4.5.2-1">This option is specified in <xref target="RFC5570"/>.</t> target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5.3">
            <name slugifiedName="name-specific-security-implications-13">Specific Security Implications">
          <t>Presence Implications</name>
            <t indent="0" pn="section-4.4.5.3-1">Presence of this option in a packet does not by itself create any
          specific new threat. Packets with this option ought not normally be
          seen on the global public Internet.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5.4">
            <name slugifiedName="name-operational-and-interoperability-im-8">Operational and Interoperability Impact if Blocked">
          <t>If If Blocked</name>
            <t indent="0" pn="section-4.4.5.4-1">If packets with this option are discarded or if the option is
          stripped from the packet during transmission from source to
          destination, then the packet itself is likely to be discarded by the
          receiver because it is not properly labeled. In some cases, the
          receiver might receive the packet but associate an incorrect
          sensitivity label
          Sensitivity Label with the received data from the packet whose CALIPSO Common Architecture Label
	  IPv6 Security Option (CALIPSO)
          was stripped by a middle-box middlebox (such as a packet-scrubber). packet scrubber). Associating an
          incorrect sensitivity label Sensitivity Label can cause the received information
          either
          to be handled either as more sensitive than it really is
          ("upgrading") or as less sensitive than it really is
            ("downgrading"), either of which is problematic. As noted in <xref target="RFC5570"/>, target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/>, IPsec <xref target="RFC4301"/> <xref target="RFC4302"/> <xref target="RFC4303"/> target="RFC4301" format="default" sectionFormat="of" derivedContent="RFC4301"/> <xref target="RFC4302" format="default" sectionFormat="of" derivedContent="RFC4302"/> <xref target="RFC4303" format="default" sectionFormat="of" derivedContent="RFC4303"/> can be employed to protect the CALIPSO option.</t> CALIPSO.</t>
          </section>
          <section title="Advice">
<t> numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.5.5">
            <name slugifiedName="name-advice-16">Advice</name>
            <t indent="0" pn="section-4.4.5.5-1">
Recommendations for handling the CALIPSO option depend on the deployment environment, environment rather than on whether an intermediate system
  happens to be deployed as a transit device (e.g., IPv6 transit router).</t>

<t>Explicit
            <t indent="0" pn="section-4.4.5.5-2">Explicit configuration is the only method via which an intermediate system
 can know whether that particular intermediate system has been
 deployed within a Multi-Level Secure (MLS) an MLS environment.  In many cases,
 ordinary commercial intermediate systems (e.g., IPv6 routers and firewalls)
 are the majority of the deployed intermediate systems inside an MLS
 network environment. </t>

<t>For Intermediate
            <t indent="0" pn="section-4.4.5.5-3">For intermediate systems that DO NOT implement <xref target="RFC5570"/>, target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/>, there
 should be a configuration option to EITHER either (a) drop packets containing
 the CALIPSO option OR or  (b) to ignore the presence of the CALIPSO option
 and forward the packets normally.  In non-MLS environments, such
 intermediate systems should have this configuration option set to (a)
 above.  In MLS environments, such intermediate systems should
 have this option set to (b) above.  The default setting for this configuration
 option should be set to (a) above, because MLS environments are much
 less common than non-MLS environments.
</t>

<t>For Intermediate
            <t indent="0" pn="section-4.4.5.5-4">For intermediate systems that DO implement <xref target="RFC5570"/>, target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/>, there should
 be configuration options (a) and (b) from the preceding paragraph and
 also a third configuration option (c) to process packets containing
 a CALIPSO option as per <xref target="RFC5570"/>. target="RFC5570" format="default" sectionFormat="of" derivedContent="RFC5570"/>.  When deployed in non-MLS
 environments, such intermediate systems should have this configuration
 option set to (a) above.  When deployed in MLS environments, such
 intermediate systems should have this configuration option set to (c).  The default setting
 for this configuration option MAY <bcp14>MAY</bcp14> be set to (a) above, because MLS
 environments are much less common than non-MLS environments.
</t>
          </section>
        </section>
        <section title="SMF_DPD (Type=0x08)"  anchor="x08">
<section title="Uses">
<t>This anchor="x08" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6">
          <name slugifiedName="name-smf_dpd-type0x08">SMF_DPD (Type=0x08)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6.1">
            <name slugifiedName="name-uses-17">Uses</name>
            <t indent="0" pn="section-4.4.6.1-1">This option is employed in the (experimental) Simplified Multicast Forwarding (SMF) for unique packet identification for IPv6 I-DPD, Identification-based DPD (I-DPD) and as a mechanism to guarantee non-collision of hash values for different packets when H-DPD Hash-based DPD (H-DPD) is used.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6.2">
            <name slugifiedName="name-specification-17">Specification</name>
            <t indent="0" pn="section-4.4.6.2-1">This option is specified in <xref target="RFC6621"/>.</t> target="RFC6621" format="default" sectionFormat="of" derivedContent="RFC6621"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6.3">
            <name slugifiedName="name-specific-security-implications-14">Specific Security Implications">
<t>None. Implications</name>
            <t indent="0" pn="section-4.4.6.3-1">None. The use of transient numeric identifiers is subject to the security and privacy considerations discussed in <xref target="I-D.irtf-pearg-numeric-ids-generation"/>.</t> target="I-D.irtf-pearg-numeric-ids-generation" format="default" sectionFormat="of" derivedContent="NUMERIC-IDS"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6.4">
            <name slugifiedName="name-operational-and-interoperability-im-9">Operational and Interoperability Impact if Blocked">
<t>Dropping If Blocked</name>
            <t indent="0" pn="section-4.4.6.4-1">Dropping packets containing this option within a MANET Mobile Ad Hoc Network (MANET) domain would break SMF. However, dropping such packets at the border of such domain would have no negative impact.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.6.5">
            <name slugifiedName="name-advice-17">Advice</name>
            <t indent="0" pn="section-4.4.6.5-1">Intermediate systems that are not within a MANET domain should discard packets that contain this option.</t>
          </section>
        </section>
        <section title="PDM (Type=0x0F)"  anchor="x0F">
<section title="Uses">
<t>This anchor="x0F" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7">
          <name slugifiedName="name-pdm-type0x0f">PDM (Type=0x0F)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7.1">
            <name slugifiedName="name-uses-18">Uses</name>
            <t indent="0" pn="section-4.4.7.1-1">This option is employed to convey sequence numbers and timing information in IPv6 packets as a basis for measurements.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7.2">
            <name slugifiedName="name-specification-18">Specification</name>
            <t indent="0" pn="section-4.4.7.2-1">This option is specified in <xref target="RFC8250"/>.</t> target="RFC8250" format="default" sectionFormat="of" derivedContent="RFC8250"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7.3">
            <name slugifiedName="name-specific-security-implications-15">Specific Security Implications">
<t>Those specified Implications</name>
            <t indent="0" pn="section-4.4.7.3-1">These are discussed in <xref target="RFC8250"/>. target="RFC8250" format="default" sectionFormat="of" derivedContent="RFC8250"/>. Additionally, since the options this option employs transient numeric identifiers, implementations may be subject to the issues discussed in <xref target="I-D.irtf-pearg-numeric-ids-generation"/>.</t> target="I-D.irtf-pearg-numeric-ids-generation" format="default" sectionFormat="of" derivedContent="NUMERIC-IDS"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7.4">
            <name slugifiedName="name-operational-and-interoperability-im-10">Operational and Interoperability Impact if Blocked">
<t>Dropping If Blocked</name>
            <t indent="0" pn="section-4.4.7.4-1">Dropping packets containing this option will result in negative interoperaiblity interoperability implications for traffic employing this option as a basis for measurements.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.7.5">
            <name slugifiedName="name-advice-18">Advice</name>
            <t indent="0" pn="section-4.4.7.5-1">Intermediate systems should not discard packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="RPL anchor="x23" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8">
          <name slugifiedName="name-rpl-option-type0x23">RPL Option (Type=0x23)" anchor="x23"> (Type=0x23)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8.1">
            <name slugifiedName="name-uses-19">Uses</name>
            <t indent="0" pn="section-4.4.8.1-1">The RPL Option provides a mechanism to include routing information with in each datagram that an a RPL router forwards.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8.2">
            <name slugifiedName="name-specification-19">Specification</name>
            <t indent="0" pn="section-4.4.8.2-1">This option is specified in <xref target="RFC9008"/>.</t> target="RFC9008" format="default" sectionFormat="of" derivedContent="RFC9008"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8.3">
            <name slugifiedName="name-specific-security-implications-16">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.8.3-1">These are discussed in <xref target="RFC9008"/>.</t> target="RFC9008" format="default" sectionFormat="of" derivedContent="RFC9008"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8.4">
            <name slugifiedName="name-operational-and-interoperability-im-11">Operational and Interoperability Impact if Blocked">
<t>This If Blocked</name>
            <t indent="0" pn="section-4.4.8.4-1">This option can survive outside of an a RPL instance. As a result, discarding packets based on the presence of this option would break some use cases for RPL (see <xref target="RFC9008"/>).</t> target="RFC9008" format="default" sectionFormat="of" derivedContent="RFC9008"/>).</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.8.5">
            <name slugifiedName="name-advice-19">Advice</name>
            <t indent="0" pn="section-4.4.8.5-1">Intermediate systems should not discard IPv6 packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="Quick-Start (Type=0x26)"  anchor="x26">
<section title="Uses">
          <t>This anchor="x26" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9">
          <name slugifiedName="name-quick-start-type0x26">Quick-Start (Type=0x26)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9.1">
            <name slugifiedName="name-uses-20">Uses</name>
            <t indent="0" pn="section-4.4.9.1-1">This IP Option option is used in the specification of Quick-Start for
          TCP and IP, which is an experimental mechanism that allows transport
          protocols, in cooperation with routers, to determine an allowed
          sending rate at the start and, at times, in the middle of a data
          transfer (e.g., after an idle period) <xref target="RFC4782"/>.</t> target="RFC4782" format="default" sectionFormat="of" derivedContent="RFC4782"/>.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9.2">
            <name slugifiedName="name-specification-20">Specification</name>
            <t indent="0" pn="section-4.4.9.2-1">This option is specified in <xref target="RFC4782"/>, target="RFC4782" format="default" sectionFormat="of" derivedContent="RFC4782"/> on the "Experimental" track.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9.3">
            <name slugifiedName="name-specific-security-implications-17">Specific Security Implications">
          <t>Section 9.6 of <xref target="RFC4782"/> Implications</name>
            <t indent="0" pn="section-4.4.9.3-1"><xref target="RFC4782" sectionFormat="of" section="9.6" format="default" derivedLink="https://rfc-editor.org/rfc/rfc4782#section-9.6" derivedContent="RFC4782"/> notes that Quick-Start is
          vulnerable to two kinds of attacks: <list style="symbols">
              <t>attacks </t>
            <ul spacing="normal" bare="false" empty="false" indent="3" pn="section-4.4.9.3-2">
              <li pn="section-4.4.9.3-2.1">attacks to increase the routers' processing and state load,
              and,</t>

              <t>attacks load
              and</li>
              <li pn="section-4.4.9.3-2.2">attacks with bogus Quick-Start Requests to temporarily tie up
              available Quick-Start bandwidth, preventing routers from
              approving Quick-Start Requests from other connections.</t>
            </list></t>

<t>We connections</li>
            </ul>
            <t indent="0" pn="section-4.4.9.3-3">We note that if routers in a given environment do not implement and enable the Quick-Start mechanism, only the general security
implications of IP options (discussed in <xref target="ipv6-options-general-implications"/>) target="ipv6-options-general-implications" format="default" sectionFormat="of" derivedContent="Section 4.2"/>) would apply.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9.4">
            <name slugifiedName="name-operational-and-interoperability-im-12">Operational and Interoperability Impact if Blocked">
          <t>The Quick-Start functionality would If Blocked</name>
            <t indent="0" pn="section-4.4.9.4-1">If packets with IPv6 Quick Start options are blocked, the host trying to establish a TCP
	    connection will fall back to not including the Quick Start option -- this means that the
	    feature will be disabled, and additional delays in TCP's connection establishment (for example) could
	    will be introduced.
          (Please see Section 4.7.2 of introduced (as discussed in <xref target="RFC4782"/>.) target="RFC4782" sectionFormat="of" section="4.7.2" format="default" derivedLink="https://rfc-editor.org/rfc/rfc4782#section-4.7.2" derivedContent="RFC4782"/>). We note,
          however, that Quick-Start has been proposed as a mechanism that could
          be of use in controlled environments, environments and not as a mechanism that
          would be intended or appropriate for ubiquitous deployment in the
          global Internet <xref target="RFC4782"/>.</t> target="RFC4782" format="default" sectionFormat="of" derivedContent="RFC4782"/>.</t>
          </section>
          <section title="Advice">
          <t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.9.5">
            <name slugifiedName="name-advice-20">Advice</name>
            <t indent="0" pn="section-4.4.9.5-1">Intermediate systems should not discard IPv6 packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="Deprecated (Type=0x4D)"  anchor="x4D">
<section title="Uses">
<t>No anchor="x4D" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10">
          <name slugifiedName="name-deprecated-type0x4d">Deprecated (Type=0x4D)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10.1">
            <name slugifiedName="name-uses-21">Uses</name>
            <t indent="0" pn="section-4.4.10.1-1">No information has been found about this option type.</t>
          </section>
          <section title="Specification">
<t>No numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10.2">
            <name slugifiedName="name-specification-21">Specification</name>
            <t indent="0" pn="section-4.4.10.2-1">No information has been found about this option type.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10.3">
            <name slugifiedName="name-specific-security-implications-18">Specific Security Implications">
<t>No Implications</name>
            <t indent="0" pn="section-4.4.10.3-1">No information has been found about this option type, and hence type; hence, it has been impossible to perform the corresponding security assessment.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10.4">
            <name slugifiedName="name-operational-and-interoperability-im-13">Operational and Interoperability Impact if Blocked">
<t>Unknown.</t>
</section>

<section title="Advice">
<t>Intermediate If Blocked</name>
            <t indent="0" pn="section-4.4.10.4-1">Unknown.</t>
          </section>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.10.5">
            <name slugifiedName="name-advice-21">Advice</name>
            <t indent="0" pn="section-4.4.10.5-1">Intermediate systems should discard packets that contain this option.</t>
          </section>
        </section>
        <section title="RPL anchor="x63" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11">
          <name slugifiedName="name-rpl-option-type0x63">RPL Option (Type=0x63)" anchor="x63"> (Type=0x63)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11.1">
            <name slugifiedName="name-uses-22">Uses</name>
            <t indent="0" pn="section-4.4.11.1-1">The RPL Option provides a mechanism to include routing information with in each datagram that an a RPL router forwards.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11.2">
            <name slugifiedName="name-specification-22">Specification</name>
            <t indent="0" pn="section-4.4.11.2-1">This option was originally specified in <xref target="RFC6553"/>. target="RFC6553" format="default" sectionFormat="of" derivedContent="RFC6553"/>. It has been deprecated by <xref target="RFC9008"/>.</t> target="RFC9008" format="default" sectionFormat="of" derivedContent="RFC9008"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11.3">
            <name slugifiedName="name-specific-security-implications-19">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.11.3-1">These are discussed in <xref target="RFC9008"/>.</t> target="RFC6553" sectionFormat="of" section="5" format="default" derivedLink="https://rfc-editor.org/rfc/rfc6553#section-5" derivedContent="RFC6553"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11.4">
            <name slugifiedName="name-operational-and-interoperability-im-14">Operational and Interoperability Impact if Blocked">
<t>This If Blocked</name>
            <t indent="0" pn="section-4.4.11.4-1">This option is meant to be employed within an a RPL instance. As a result, discarding packets based on the presence of this option outside of an a RPL instance will not result in interoperability implications.</t>
          </section>
          <section title="Advice">
<t>Non-RPL routers numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.11.5">
            <name slugifiedName="name-advice-22">Advice</name>
            <t indent="0" pn="section-4.4.11.5-1">Intermediate systems should discard packets that contain an a RPL option.</t> Option.</t>
          </section>
        </section>
        <section title="MPL anchor="x6D" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12">
          <name slugifiedName="name-mpl-option-type0x6d">MPL Option (Type=0x6D)"  anchor="x6D"> (Type=0x6D)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12.1">
            <name slugifiedName="name-uses-23">Uses</name>
            <t indent="0" pn="section-4.4.12.1-1">This option is used with the Multicast Protocol for Low power and Lossy Networks (MPL), that which provides IPv6 multicast forwarding in
   constrained networks.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12.2">
            <name slugifiedName="name-specification-23">Specification</name>
            <t indent="0" pn="section-4.4.12.2-1">This option is specified in <xref target="RFC7731"/>, target="RFC7731" format="default" sectionFormat="of" derivedContent="RFC7731"/> and is meant to be included only in Hop-by-Hop Option Options headers.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12.3">
            <name slugifiedName="name-specific-security-implications-20">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.12.3-1">These are discussed in <xref target="RFC7731"/>.</t> target="RFC7731" format="default" sectionFormat="of" derivedContent="RFC7731"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12.4">
            <name slugifiedName="name-operational-and-interoperability-im-15">Operational and Interoperability Impact if Blocked">
<t>Dropping If Blocked</name>
            <t indent="0" pn="section-4.4.12.4-1">Dropping packets that contain an MPL option Option within an MPL network would break the Multicast Protocol for Low power and Lossy Networks (MPL). MPL. However, dropping such packets at the border of such networks will have no negative impact.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.12.5">
            <name slugifiedName="name-advice-23">Advice</name>
            <t indent="0" pn="section-4.4.12.5-1">Intermediate systems should not discard packets based on the presence of this option. However, since this option has been specified for the Hop-by-Hop Options, Options header, such systems should consider the discussion in <xref target="proto0"/>.</t> target="proto0" format="default" sectionFormat="of" derivedContent="Section 3.5.1"/>.</t>
          </section>
        </section>
        <section title="Endpoint anchor="x8A" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13">
          <name slugifiedName="name-endpoint-identification-typ">Endpoint Identification (Type=0x8A)" anchor="x8A"> (Type=0x8A)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13.1">
            <name slugifiedName="name-uses-24">Uses</name>
            <t indent="0" pn="section-4.4.13.1-1">The Endpoint Identification option was meant to be used with the Nimrod routing architecture <xref target="NIMROD-DOC"/>, target="NIMROD-DOC" format="default" sectionFormat="of" derivedContent="NIMROD-DOC"/> but has never seen widespread deployment.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13.2">
            <name slugifiedName="name-specification-24">Specification</name>
            <t indent="0" pn="section-4.4.13.2-1">This option is specified in <xref target="NIMROD-DOC"/>.</t> target="NIMROD-DOC" format="default" sectionFormat="of" derivedContent="NIMROD-DOC"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13.3">
            <name slugifiedName="name-specific-security-implications-21">Specific Security Implications">
<t>Undetermined.</t> Implications</name>
            <t indent="0" pn="section-4.4.13.3-1">Undetermined.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13.4">
            <name slugifiedName="name-operational-and-interoperability-im-16">Operational and Interoperability Impact if Blocked">
<t>None.</t>
</section>

<section title="Advice">
<t>Intermediate If Blocked</name>
            <t indent="0" pn="section-4.4.13.4-1">None.</t>
          </section>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.13.5">
            <name slugifiedName="name-advice-24">Advice</name>
            <t indent="0" pn="section-4.4.13.5-1">Intermediate systems should discard packets that contain this option.</t>
          </section>
        </section>
        <section title="ILNP anchor="x8B" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14">
          <name slugifiedName="name-ilnp-nonce-type0x8b">ILNP Nonce (Type=0x8B)" anchor="x8B"> (Type=0x8B)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14.1">
            <name slugifiedName="name-uses-25">Uses</name>
            <t indent="0" pn="section-4.4.14.1-1">This option is employed by the Identifier-Locator Network Protocol for IPv6 (ILNPv6) for providing to provide protection against off-path attacks for packets when ILNPv6 is in use, use and as a signal during initial network-layer session creation that ILNPv6 is proposed for use with this network-layer session, rather than classic IPv6.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14.2">
            <name slugifiedName="name-specification-25">Specification</name>
            <t indent="0" pn="section-4.4.14.2-1">This option is specified in <xref target="RFC6744"/>.</t> target="RFC6744" format="default" sectionFormat="of" derivedContent="RFC6744"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14.3">
            <name slugifiedName="name-specific-security-implications-22">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.14.3-1">These are discussed in <xref target="RFC6744"/>.</t> target="RFC6744" format="default" sectionFormat="of" derivedContent="RFC6744"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14.4">
            <name slugifiedName="name-operational-and-interoperability-im-17">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.14.4-1">Discarding packets that contain this option will break INLPv6 ILNPv6 deployments.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.14.5">
            <name slugifiedName="name-advice-25">Advice</name>
            <t indent="0" pn="section-4.4.14.5-1">Intermediate systems should not discard packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="Line-Identification anchor="x8C" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15">
          <name slugifiedName="name-line-identification-option-">Line-Identification Option (Type=0x8C)" anchor="x8C"> (Type=0x8C)</name>
          <section title="Uses">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15.1">
            <name slugifiedName="name-uses-26">Uses</name>
            <t indent="0" pn="section-4.4.15.1-1">This option is used by an Edge Router to identify the subscriber premises in scenarios where several subscriber premises may be logically connected to the same interface of an Edge Router.</t>

<!--
   The Line-Identification Option (LIO) is a destination option that can
   be included in IPv6 datagrams that tunnel Router Solicitation and
   Router Advertisement messages.  The use of the Line-ID option in any
   other IPv6 datagrams is not defined by this document.  Multiple Line-
   ID destination options MUST NOT be present in the same IPv6 datagram.
   The LIO has no alignment requirement.
-->
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15.2">
            <name slugifiedName="name-specification-26">Specification</name>
            <t indent="0" pn="section-4.4.15.2-1">This option is specified in <xref target="RFC6788"/>.</t> target="RFC6788" format="default" sectionFormat="of" derivedContent="RFC6788"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15.3">
            <name slugifiedName="name-specific-security-implications-23">Specific Security Implications">
<t>Those described Implications</name>
            <t indent="0" pn="section-4.4.15.3-1">These are discussed in <xref target="RFC6788"/>.</t> target="RFC6788" format="default" sectionFormat="of" derivedContent="RFC6788"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15.4">
            <name slugifiedName="name-operational-and-interoperability-im-18">Operational and Interoperability Impact if Blocked">
<t>Since If Blocked</name>
            <t indent="0" pn="section-4.4.15.4-1">Since this option is meant to be employed used when tunneling Neighbor Discovery messages in Router Solicitation messages, some broadband network deployment scenarios, discarding packets based on the presence of this option at intermediate systems will result in no interoperability implications.</t>
          </section>
          <section title="Advice">
<t>Intermediate devices numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.15.5">
            <name slugifiedName="name-advice-26">Advice</name>
            <t indent="0" pn="section-4.4.15.5-1">Intermediate systems should discard packets that contain this option.</t>
          </section>
        </section>
        <section title="Jumbo anchor="xC2" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16">
          <name slugifiedName="name-jumbo-payload-type0xc2">Jumbo Payload (Type=0XC2)"  anchor="xC2"> (Type=0XC2)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16.1">
            <name slugifiedName="name-uses-27">Uses</name>
            <t indent="0" pn="section-4.4.16.1-1">The Jumbo payload Payload option provides the means of specifying for supporting payloads larger than 65535 bytes.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16.2">
            <name slugifiedName="name-specification-27">Specification</name>
            <t indent="0" pn="section-4.4.16.2-1">This option is specified in <xref target="RFC2675"/>.</t> target="RFC2675" format="default" sectionFormat="of" derivedContent="RFC2675"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16.3">
            <name slugifiedName="name-specific-security-implications-24">Specific Security Implications">
<t>There Implications</name>
            <t indent="0" pn="section-4.4.16.3-1">There are no specific issues arising from this option, except for improper validity checks of the option and associated packet lengths.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16.4">
            <name slugifiedName="name-operational-and-interoperability-im-19">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.16.4-1">Discarding packets based on the presence of this option will cause IPv6 jumbograms to be discarded.</t>
          </section>
          <section title="Advice">
<t>An numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.16.5">
            <name slugifiedName="name-advice-27">Advice</name>
            <t indent="0" pn="section-4.4.16.5-1">An operator should permit this option only in specific scenarios in which support for IPv6 jumbograms is desired. required.
</t>
          </section>
        </section>
        <section title="Home anchor="xC9" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17">
          <name slugifiedName="name-home-address-type0xc9">Home Address (Type=0xC9)" anchor="xC9"> (Type=0xC9)</name>
          <section title="Uses">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17.1">
            <name slugifiedName="name-uses-28">Uses</name>
            <t indent="0" pn="section-4.4.17.1-1">The Home Address option is used by a Mobile IPv6 node while away from home, home to inform the recipient of the mobile node's home address.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17.2">
            <name slugifiedName="name-specification-28">Specification</name>
            <t indent="0" pn="section-4.4.17.2-1">This option is specified in <xref target="RFC6275"/>.</t> target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17.3">
            <name slugifiedName="name-specific-security-implications-25">Specific Security Implications">
<t>No Implications</name>
            <t indent="0" pn="section-4.4.17.3-1">There are no (known) additional security implications implications, other than those described discussed in <xref target="RFC6275"/>.</t> target="RFC6275" format="default" sectionFormat="of" derivedContent="RFC6275"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17.4">
            <name slugifiedName="name-operational-and-interoperability-im-20">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
            <t indent="0" pn="section-4.4.17.4-1">Discarding IPv6 packets based on the presence of this option will break Mobile IPv6.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.17.5">
            <name slugifiedName="name-advice-28">Advice</name>
            <t indent="0" pn="section-4.4.17.5-1">Intermediate systems should not discard IPv6 packets based on the presence of this option.</t>
          </section>
        </section>
        <section title="IP_DFF (Type=0xEE)"  anchor="xEE">
<section title="Uses">
<t>This anchor="xEE" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18">
          <name slugifiedName="name-ip_dff-type0xee">IP_DFF (Type=0xEE)</name>
          <section numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18.1">
            <name slugifiedName="name-uses-29">Uses</name>
            <t indent="0" pn="section-4.4.18.1-1">This option is employed with the (Experimental) (experimental) Depth-First Forwarding (DFF) in Unreliable Networks.</t> unreliable networks.</t>
          </section>
          <section title="Specification">
<t>This numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18.2">
            <name slugifiedName="name-specification-29">Specification</name>
            <t indent="0" pn="section-4.4.18.2-1">This option is specified in <xref target="RFC6971"/>.</t> target="RFC6971" format="default" sectionFormat="of" derivedContent="RFC6971"/>.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18.3">
            <name slugifiedName="name-specific-security-implications-26">Specific Security Implications">
<t>Those Implications</name>
            <t indent="0" pn="section-4.4.18.3-1">These are specified in <xref target="RFC6971"/>.</t> target="RFC6971" format="default" sectionFormat="of" derivedContent="RFC6971"/>.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18.4">
            <name slugifiedName="name-operational-and-interoperability-im-21">Operational and Interoperability Impact if Blocked">
<t>Dropping If Blocked</name>
            <t indent="0" pn="section-4.4.18.4-1">Dropping packets containing this option within a routing domain that is running DFF would break DFF. However, dropping such packets at the border of such domains will have no security operational or interoperability implications.</t>
          </section>
          <section title="Advice">
<t>Intermediate numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.18.5">
            <name slugifiedName="name-advice-29">Advice</name>
            <t indent="0" pn="section-4.4.18.5-1">Intermediate systems that do not operate within a routing domain that is running DFF should discard packets containing this option.</t>
          </section>
        </section>
        <section title="RFC3692-style anchor="x1E" numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19">
          <name slugifiedName="name-rfc3692-style-experiment-ty">RFC3692-Style Experiment (Types = 0x1E, 0x3E, 0x5E, 0x7E, 0x9E, 0xBE, 0xDE, 0xFE)" anchor="x1E"> 0xFE)</name>
          <section title="Uses">
          <t>These numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19.1">
            <name slugifiedName="name-uses-30">Uses</name>
            <t indent="0" pn="section-4.4.19.1-1">These options can be employed for performing RFC3692-style experiments. It is only appropriate to use these values in
          explicitly configured experiments; they must not be shipped as defaults in implementations.</t>
          </section>
          <section title="Specification">
         <t>Specified numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19.2">
            <name slugifiedName="name-specification-30">Specification</name>
            <t indent="0" pn="section-4.4.19.2-1">These options are specified in RFC 4727 <xref target="RFC4727"/> target="RFC4727" format="default" sectionFormat="of" derivedContent="RFC4727"/> in the context of
          RFC3692-style experiments.</t>
          </section>
          <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19.3">
            <name slugifiedName="name-specific-security-implications-27">Specific Security Implications">
 <t>The Implications</name>
            <t indent="0" pn="section-4.4.19.3-1">The specific security implications will depend on the specific use of these options.</t>
          </section>
          <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19.4">
            <name slugifiedName="name-operational-and-interoperability-im-22">Operational and Interoperability Impact if Blocked">
<t>For If Blocked</name>
            <t indent="0" pn="section-4.4.19.4-1">For obvious reasons, discarding packets that contain these options limits the ability to perform legitimate experiments across IPv6 routers.</t>
          </section>
          <section title="Advice">
<t>Operators numbered="true" toc="exclude" removeInRFC="false" pn="section-4.4.19.5">
            <name slugifiedName="name-advice-30">Advice</name>
            <t indent="0" pn="section-4.4.19.5-1">Operators should determine determine, according to their own circumstances circumstances, whether to discard packets containing these IPv6 options.</t>
<!--
<t>Intermediate systems should discard packets that contain these options. Only in specific environments where RFC3692-style experiments are meant to be performed should these options be permitted.</t> -->
          </section>
        </section>
      </section>
      <section title="Advice numbered="true" toc="include" removeInRFC="false" pn="section-4.5">
        <name slugifiedName="name-advice-on-the-handling-of-pac">Advice on the handling Handling of Packets with Unknown IPv6 Options">

<t>We Options</name>
        <t indent="0" pn="section-4.5-1">We refer to IPv6 options that have not been assigned an IPv6 option type Option Type in the corresponding registry (<xref target="IANA-IPV6-PARAM"/>) registry, which is <xref target="IANA-IPV6-PARAM" format="default" sectionFormat="of" derivedContent="IANA-IPV6-PARAM"/>, as "unknown IPv6 options".</t>
        <section title="Uses">
          <t>New numbered="true" toc="exclude" removeInRFC="false" pn="section-4.5.1">
          <name slugifiedName="name-uses-31">Uses</name>
          <t indent="0" pn="section-4.5.1-1">New IPv6 options may be specified as part of future protocol work.</t>
        </section>
        <section title="Specification">
<t>The numbered="true" toc="exclude" removeInRFC="false" pn="section-4.5.2">
          <name slugifiedName="name-specification-31">Specification</name>
          <t indent="0" pn="section-4.5.2-1">The processing of unknown IPv6 options is specified in <xref target="RFC8200"/>.</t> target="RFC8200" format="default" sectionFormat="of" derivedContent="RFC8200"/>.</t>
        </section>
        <section title="Specific numbered="true" toc="exclude" removeInRFC="false" pn="section-4.5.3">
          <name slugifiedName="name-specific-security-implications-28">Specific Security Implications">
 <t>For Implications</name>
          <t indent="0" pn="section-4.5.3-1">For obvious reasons, it is impossible to determine specific security implications of unknown IPv6 options.</t>
        </section>
        <section title="Operational numbered="true" toc="exclude" removeInRFC="false" pn="section-4.5.4">
          <name slugifiedName="name-operational-and-interoperability-im-23">Operational and Interoperability Impact if Blocked">
<t>Discarding If Blocked</name>
          <t indent="0" pn="section-4.5.4-1">Discarding unknown IPv6 options may slow down the deployment of new IPv6 options. As noted in <xref target="draft-gont-6man-ipv6-opt-transmit"/>, target="I-D.gont-6man-ipv6-opt-transmit" format="default" sectionFormat="of" derivedContent="IPv6-OPTIONS"/>, the corresponding IANA registry (<xref target="IANA-IPV6-PARAM"/> registry, which is <xref target="IANA-IPV6-PARAM" format="default" sectionFormat="of" derivedContent="IANA-IPV6-PARAM"/>, should be monitored such that IPv6 option filtering rules are updated as new IPv6 options are standardized.</t>
        </section>
        <section title="Advice">

<t>Operators numbered="true" toc="exclude" removeInRFC="false" pn="section-4.5.5">
          <name slugifiedName="name-advice-31">Advice</name>
          <t indent="0" pn="section-4.5.5-1">Operators should determine determine, according to their own circumstances circumstances, whether to discard packets containing unknown IPv6 options.</t>
        </section>
      </section>
    </section>
    <section anchor="IANA" title="IANA Considerations">
    <t>This numbered="true" toc="include" removeInRFC="false" pn="section-5">
      <name slugifiedName="name-iana-considerations">IANA Considerations</name>
      <t indent="0" pn="section-5-1">This document has no actions for IANA.</t> IANA actions.</t>
    </section>
    <section title="Privacy Considerations" anchor="Privacy" >
<t> numbered="true" toc="include" removeInRFC="false" pn="section-6">
      <name slugifiedName="name-privacy-considerations">Privacy Considerations</name>
      <t indent="0" pn="section-6-1">
There are no privacy considerations associated with this document.
</t>
    </section>
    <section title="Security Considerations" anchor="Security" >
<t> numbered="true" toc="include" removeInRFC="false" pn="section-7">
      <name slugifiedName="name-security-considerations">Security Considerations</name>
      <t indent="0" pn="section-7-1">
This document provides advice on the filtering of IPv6 packets that contain IPv6 EHs (and possibly IPv6 options) at IPv6 transit routers. It is meant to improve the current situation of widespread dropping of such IPv6 packets in those cases where the drops result from improper configuration defaults, defaults or inappropriate advice in this area.
</t>
<t>
      <t indent="0" pn="section-7-2">
   As discussed in Section <xref target="ipv6-ehs-rationale"/> of this document, target="ipv6-ehs-rationale" format="default" sectionFormat="of" derivedContent="Section 3.3"/>, one of the
   underlying principles for the advice provided in this document is
   that IPv6 packets with specific EHs or options which that may represent an
   attack vector for infrastructure devices should be dropped. While
   this policy helps mitigate some specific attack vectors, the
   recommendations in this document will not help to mitigate
   vulnerabilities based on implementation errors <xref target="RFC9098"/>. target="RFC9098" format="default" sectionFormat="of" derivedContent="RFC9098"/>.
</t>

<t>We
      <t indent="0" pn="section-7-3">We also note that depending on the router architecture, attempts to filter packets ased based on the presence of IPv6 EHs or options might itself represent an attack vector to network infrastructure devices <xref target="RFC9098"/>.</t> target="RFC9098" format="default" sectionFormat="of" derivedContent="RFC9098"/>.</t>
    </section>

<section title="Acknowledgements">
<t>The
  </middle>
  <back>
    <displayreference target="I-D.irtf-pearg-numeric-ids-generation" to="NUMERIC-IDS"/>
    <displayreference target="I-D.vyncke-v6ops-james" to="JAMES"/>
    <displayreference target="I-D.gont-6man-ipv6-opt-transmit" to="IPv6-OPTIONS"/>
    <references pn="section-8">
      <name slugifiedName="name-references">References</name>
      <references pn="section-8.1">
        <name slugifiedName="name-normative-references">Normative References</name>
        <reference anchor="RFC1034" target="https://www.rfc-editor.org/info/rfc1034" quoteTitle="true" derivedAnchor="RFC1034">
          <front>
            <title>Domain names - concepts and facilities</title>
            <author initials="P." surname="Mockapetris" fullname="P. Mockapetris">
              <organization showOnFrontPage="true"/>
            </author>
            <date year="1987" month="November"/>
            <abstract>
              <t indent="0">This RFC is the revised basic definition of The Domain Name System.  It obsoletes RFC-882.  This memo describes the domain style names and their used for host address look up and electronic mail forwarding.  It discusses the clients and servers in the domain name system and the protocol used between them.</t>
            </abstract>
          </front>
          <seriesInfo name="STD" value="13"/>
          <seriesInfo name="RFC" value="1034"/>
          <seriesInfo name="DOI" value="10.17487/RFC1034"/>
        </reference>
        <reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2119" quoteTitle="true" derivedAnchor="RFC2119">
          <front>
            <title>Key words for use in RFCs to Indicate Requirement Levels</title>
            <author fullname="S. Bradner" initials="S" surname="Bradner"/>
            <date month="March" year="1997"/>
            <abstract>
              <t indent="0">In many standards track documents several words are used to signify the requirements in the specification.  These words are often capitalized.  This document defines these words as they should be interpreted in IETF documents.  This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="14"/>
          <seriesInfo name="RFC" value="2119"/>
          <seriesInfo name="DOI" value="10.17487/RFC2119"/>
        </reference>
        <reference anchor="RFC2205" target="https://www.rfc-editor.org/info/rfc2205" quoteTitle="true" derivedAnchor="RFC2205">
          <front>
            <title>Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification</title>
            <author fullname="R. Braden" initials="R" role="editor" surname="Braden"/>
            <author fullname="L. Zhang" initials="L" surname="Zhang"/>
            <author fullname="S. Berson" initials="S" surname="Berson"/>
            <author fullname="S. Herzog" initials="S" surname="Herzog"/>
            <author fullname="S. Jamin" initials="S" surname="Jamin"/>
            <date month="September" year="1997"/>
            <abstract>
              <t indent="0">This memo describes version 1 of RSVP, a resource reservation setup protocol designed for an integrated services Internet.  RSVP provides receiver-initiated setup of resource reservations for multicast or unicast data flows, with good scaling and robustness properties. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2205"/>
          <seriesInfo name="DOI" value="10.17487/RFC2205"/>
        </reference>
        <reference anchor="RFC2473" target="https://www.rfc-editor.org/info/rfc2473" quoteTitle="true" derivedAnchor="RFC2473">
          <front>
            <title>Generic Packet Tunneling in IPv6 Specification</title>
            <author fullname="A. Conta" initials="A" surname="Conta"/>
            <author fullname="S. Deering" initials="S" surname="Deering"/>
            <date month="December" year="1998"/>
            <abstract>
              <t indent="0">This document defines the model and generic mechanisms for IPv6 encapsulation of Internet packets, such as IPv6 and IPv4. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2473"/>
          <seriesInfo name="DOI" value="10.17487/RFC2473"/>
        </reference>
        <reference anchor="RFC2675" target="https://www.rfc-editor.org/info/rfc2675" quoteTitle="true" derivedAnchor="RFC2675">
          <front>
            <title>IPv6 Jumbograms</title>
            <author fullname="D. Borman" initials="D" surname="Borman"/>
            <author fullname="S. Deering" initials="S" surname="Deering"/>
            <author fullname="R. Hinden" initials="R" surname="Hinden"/>
            <date month="August" year="1999"/>
            <abstract>
              <t indent="0">This document describes the IPv6 Jumbo Payload option, which provides the means of specifying such large payload lengths.  It also describes the changes needed to TCP and UDP to make use of jumbograms. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2675"/>
          <seriesInfo name="DOI" value="10.17487/RFC2675"/>
        </reference>
        <reference anchor="RFC2710" target="https://www.rfc-editor.org/info/rfc2710" quoteTitle="true" derivedAnchor="RFC2710">
          <front>
            <title>Multicast Listener Discovery (MLD) for IPv6</title>
            <author fullname="S. Deering" initials="S" surname="Deering"/>
            <author fullname="W. Fenner" initials="W" surname="Fenner"/>
            <author fullname="B. Haberman" initials="B" surname="Haberman"/>
            <date month="October" year="1999"/>
            <abstract>
              <t indent="0">This document specifies the protocol used by an IPv6 router to discover the presence of multicast listeners (that is, nodes wishing to receive multicast packets) on its directly attached links, and to discover specifically which multicast addresses are of interest to those neighboring nodes. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2710"/>
          <seriesInfo name="DOI" value="10.17487/RFC2710"/>
        </reference>
        <reference anchor="RFC2711" target="https://www.rfc-editor.org/info/rfc2711" quoteTitle="true" derivedAnchor="RFC2711">
          <front>
            <title>IPv6 Router Alert Option</title>
            <author fullname="C. Partridge" initials="C" surname="Partridge"/>
            <author fullname="A. Jackson" initials="A" surname="Jackson"/>
            <date month="October" year="1999"/>
            <abstract>
              <t indent="0">This memo describes a new IPv6 Hop-by-Hop Option type that alerts transit routers to more closely examine the contents of an IP datagram. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2711"/>
          <seriesInfo name="DOI" value="10.17487/RFC2711"/>
        </reference>
        <reference anchor="RFC3692" target="https://www.rfc-editor.org/info/rfc3692" quoteTitle="true" derivedAnchor="RFC3692">
          <front>
            <title>Assigning Experimental and Testing Numbers Considered Useful</title>
            <author fullname="T. Narten" initials="T" surname="Narten"/>
            <date month="January" year="2004"/>
            <abstract>
              <t indent="0">When experimenting with or extending protocols, it is often necessary to use some sort of protocol number or constant in order to actually test or experiment with the new function, even when testing in a closed environment.  For example, to test a new DHCP option, one needs an option number to identify the new function.  This document recommends that when writing IANA Considerations sections, authors would like should consider assigning a small range of numbers for experimentation purposes that implementers can use when testing protocol extensions or other new features.  This document reserves some ranges of numbers for experimentation purposes in specific protocols where the need to thank Ron Bonica support experimentation has been identified.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="82"/>
          <seriesInfo name="RFC" value="3692"/>
          <seriesInfo name="DOI" value="10.17487/RFC3692"/>
        </reference>
        <reference anchor="RFC3810" target="https://www.rfc-editor.org/info/rfc3810" quoteTitle="true" derivedAnchor="RFC3810">
          <front>
            <title>Multicast Listener Discovery Version 2 (MLDv2) for his work IPv6</title>
            <author fullname="R. Vida" initials="R" role="editor" surname="Vida"/>
            <author fullname="L. Costa" initials="L" role="editor" surname="Costa"/>
            <date month="June" year="2004"/>
            <abstract>
              <t indent="0">This document updates RFC 2710, and it specifies Version 2 of the ulticast Listener Discovery Protocol (MLDv2).  MLD is used by an IPv6 router to discover the presence of multicast listeners on earlier versions directly attached links, and to discover which multicast addresses are of interest to those neighboring nodes.  MLDv2 is designed to be interoperable with MLDv1.  MLDv2 adds the ability for a node to report interest in listening to packets with a particular multicast address only from specific source addresses or from all sources except for specific source addresses. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="3810"/>
          <seriesInfo name="DOI" value="10.17487/RFC3810"/>
        </reference>
        <reference anchor="RFC4286" target="https://www.rfc-editor.org/info/rfc4286" quoteTitle="true" derivedAnchor="RFC4286">
          <front>
            <title>Multicast Router Discovery</title>
            <author fullname="B. Haberman" initials="B" surname="Haberman"/>
            <author fullname="J. Martin" initials="J" surname="Martin"/>
            <date month="December" year="2005"/>
            <abstract>
              <t indent="0">The concept of Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) snooping requires the ability to identify the location of multicast routers. Since snooping is not standardized, there are many mechanisms in use to identify the multicast routers. However, this document.</t>
<t>The authors can lead to interoperability issues between multicast routers and snooping switches from different vendors.</t>
              <t indent="0">This document introduces a general mechanism that allows for the discovery of multicast routers. This new mechanism, Multicast Router Discovery (MRD), introduces a standardized means of identifying multicast routers without a dependency on particular multicast routing protocols. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4286"/>
          <seriesInfo name="DOI" value="10.17487/RFC4286"/>
        </reference>
        <reference anchor="RFC4301" target="https://www.rfc-editor.org/info/rfc4301" quoteTitle="true" derivedAnchor="RFC4301">
          <front>
            <title>Security Architecture for the Internet Protocol</title>
            <author fullname="S. Kent" initials="S" surname="Kent"/>
            <author fullname="K. Seo" initials="K" surname="Seo"/>
            <date month="December" year="2005"/>
            <abstract>
              <t indent="0">This document describes an updated version of the "Security Architecture for IP", which is designed to provide security services for traffic at the IP layer.  This document obsoletes RFC 2401 (November 1998). [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4301"/>
          <seriesInfo name="DOI" value="10.17487/RFC4301"/>
        </reference>
        <reference anchor="RFC4302" target="https://www.rfc-editor.org/info/rfc4302" quoteTitle="true" derivedAnchor="RFC4302">
          <front>
            <title>IP Authentication Header</title>
            <author fullname="S. Kent" initials="S" surname="Kent"/>
            <date month="December" year="2005"/>
            <abstract>
              <t indent="0">This document describes an updated version of the IP Authentication Header (AH), which is designed to provide authentication services in IPv4 and IPv6.  This document obsoletes RFC 2402 (November 1998). [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4302"/>
          <seriesInfo name="DOI" value="10.17487/RFC4302"/>
        </reference>
        <reference anchor="RFC4303" target="https://www.rfc-editor.org/info/rfc4303" quoteTitle="true" derivedAnchor="RFC4303">
          <front>
            <title>IP Encapsulating Security Payload (ESP)</title>
            <author fullname="S. Kent" initials="S" surname="Kent"/>
            <date month="December" year="2005"/>
            <abstract>
              <t indent="0">This document describes an updated version of the Encapsulating Security Payload (ESP) protocol, which is designed to provide a mix of security services in IPv4 and IPv6.  ESP is used to provide confidentiality, data origin authentication, connectionless integrity, an anti-replay service (a form of partial sequence integrity), and limited traffic flow confidentiality.  This document obsoletes RFC 2406 (November 1998). [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4303"/>
          <seriesInfo name="DOI" value="10.17487/RFC4303"/>
        </reference>
        <reference anchor="RFC4727" target="https://www.rfc-editor.org/info/rfc4727" quoteTitle="true" derivedAnchor="RFC4727">
          <front>
            <title>Experimental Values In IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP Headers</title>
            <author fullname="B. Fenner" initials="B" surname="Fenner"/>
            <date month="November" year="2006"/>
            <abstract>
              <t indent="0">When experimenting with or extending protocols, it is often necessary to use some sort of protocol number or constant in order to actually test or experiment with the new function, even when testing in a closed environment.  This document reserves some ranges of numbers for experimentation purposes in specific protocols where the need to support experimentation has been identified, and it describes the numbers that have already been reserved by other documents. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4727"/>
          <seriesInfo name="DOI" value="10.17487/RFC4727"/>
        </reference>
        <reference anchor="RFC4782" target="https://www.rfc-editor.org/info/rfc4782" quoteTitle="true" derivedAnchor="RFC4782">
          <front>
            <title>Quick-Start for TCP and IP</title>
            <author fullname="S. Floyd" initials="S" surname="Floyd"/>
            <author fullname="M. Allman" initials="M" surname="Allman"/>
            <author fullname="A. Jain" initials="A" surname="Jain"/>
            <author fullname="P. Sarolahti" initials="P" surname="Sarolahti"/>
            <date month="January" year="2007"/>
            <abstract>
              <t indent="0">This document specifies an optional Quick-Start mechanism for transport protocols, in cooperation with routers, to determine an allowed sending rate at the start and, at times, in the middle of a data transfer (e.g., after an idle period). While Quick-Start is designed to be used by a range of transport protocols, in this document we only specify its use with TCP. Quick-Start is designed to allow connections to use higher sending rates when there is significant unused bandwidth along the path, and the sender and all of the routers along the path approve the Quick-Start Request.</t>
              <t indent="0">This document describes many paths where Quick-Start Requests would not be approved. These paths include all paths containing routers, IP tunnels, MPLS paths, and the like that do not support Quick- Start. These paths also include paths with routers or middleboxes that drop packets containing IP options. Quick-Start Requests could be difficult to thank (in alphabetical order) Mikael Abrahamsson, Brian Carpenter, Tim Chown, Roman Danyliw, Darren Dukes, Lars Eggert, David Farmer, Mike Heard, Bob Hinden, Christian Huitema, Benjamin Kaduk, Erik Kline, Murray Kucherawy, Jen Linkova, Carlos Pignataro, Alvaro Retana, Maria Ines Robles, Zaheduzzaman Sarker, Donald Smith, Pascal Thubert, Ole Troan, Gunter Van De Velde, Eric Vyncke, approve over paths that include multi-access layer- two networks. This document also describes environments where the Quick-Start process could fail with false positives, with the sender incorrectly assuming that the Quick-Start Request had been approved by all of the routers along the path. As a result of these concerns, and as a result of the difficulties and Robert Wilton, seeming absence of motivation for routers, such as core routers to deploy Quick-Start, Quick-Start is being proposed as a mechanism that could be of use in controlled environments, and not as a mechanism that would be intended or appropriate for ubiquitous deployment in the global Internet. This memo defines an Experimental Protocol for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4782"/>
          <seriesInfo name="DOI" value="10.17487/RFC4782"/>
        </reference>
        <reference anchor="RFC5095" target="https://www.rfc-editor.org/info/rfc5095" quoteTitle="true" derivedAnchor="RFC5095">
          <front>
            <title>Deprecation of Type 0 Routing Headers in IPv6</title>
            <author fullname="J. Abley" initials="J" surname="Abley"/>
            <author fullname="P. Savola" initials="P" surname="Savola"/>
            <author fullname="G. Neville-Neil" initials="G" surname="Neville-Neil"/>
            <date month="December" year="2007"/>
            <abstract>
              <t indent="0">The functionality provided by IPv6's Type 0 Routing Header can be exploited in order to achieve traffic amplification over a remote path for the purposes of generating denial-of-service traffic.  This document updates the IPv6 specification to deprecate the use of IPv6 Type 0 Routing Headers, in light of this security concern. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5095"/>
          <seriesInfo name="DOI" value="10.17487/RFC5095"/>
        </reference>
        <reference anchor="RFC5533" target="https://www.rfc-editor.org/info/rfc5533" quoteTitle="true" derivedAnchor="RFC5533">
          <front>
            <title>Shim6: Level 3 Multihoming Shim Protocol for IPv6</title>
            <author fullname="E. Nordmark" initials="E" surname="Nordmark"/>
            <author fullname="M. Bagnulo" initials="M" surname="Bagnulo"/>
            <date month="June" year="2009"/>
            <abstract>
              <t indent="0">This document defines the Shim6 protocol, a layer 3 shim for providing valuable comments locator agility below the transport protocols, so that multihoming can be provided for IPv6 with failover and load-sharing properties, without assuming that a multihomed site will have a provider-independent IPv6 address prefix announced in the global IPv6 routing table.  The hosts in a site that has multiple provider- allocated IPv6 address prefixes will use the Shim6 protocol specified in this document to set up state with peer hosts so that the state can later be used to failover to a different locator pair, should the original one stop working. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5533"/>
          <seriesInfo name="DOI" value="10.17487/RFC5533"/>
        </reference>
        <reference anchor="RFC5570" target="https://www.rfc-editor.org/info/rfc5570" quoteTitle="true" derivedAnchor="RFC5570">
          <front>
            <title>Common Architecture Label IPv6 Security Option (CALIPSO)</title>
            <author fullname="M. StJohns" initials="M" surname="StJohns"/>
            <author fullname="R. Atkinson" initials="R" surname="Atkinson"/>
            <author fullname="G. Thomas" initials="G" surname="Thomas"/>
            <date month="July" year="2009"/>
            <abstract>
              <t indent="0">This document describes an optional method for encoding explicit packet Sensitivity Labels on earlier versions IPv6 packets.  It is intended for use only within Multi-Level Secure (MLS) networking environments that are both trusted and trustworthy.  This memo provides information for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5570"/>
          <seriesInfo name="DOI" value="10.17487/RFC5570"/>
        </reference>
        <reference anchor="RFC5971" target="https://www.rfc-editor.org/info/rfc5971" quoteTitle="true" derivedAnchor="RFC5971">
          <front>
            <title>GIST: General Internet Signalling Transport</title>
            <author fullname="H. Schulzrinne" initials="H" surname="Schulzrinne"/>
            <author fullname="R. Hancock" initials="R" surname="Hancock"/>
            <date month="October" year="2010"/>
            <abstract>
              <t indent="0">This document specifies protocol stacks for the routing and transport of per-flow signalling messages along the path taken by that flow through the network.  The design uses existing transport and security protocols under a common messaging layer, the General Internet Signalling Transport (GIST), which provides a common service for diverse signalling applications.  GIST does not handle signalling application state itself, but manages its own internal state and the configuration of the underlying transport and security protocols to enable the transfer of messages in both directions along the flow path.  The combination of GIST and the lower layer transport and security protocols provides a solution for the base protocol component of the "Next Steps in Signalling" (NSIS) framework.  This document defines an Experimental Protocol for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5971"/>
          <seriesInfo name="DOI" value="10.17487/RFC5971"/>
        </reference>
        <reference anchor="RFC6275" target="https://www.rfc-editor.org/info/rfc6275" quoteTitle="true" derivedAnchor="RFC6275">
          <front>
            <title>Mobility Support in IPv6</title>
            <author fullname="C. Perkins" initials="C" role="editor" surname="Perkins"/>
            <author fullname="D. Johnson" initials="D" surname="Johnson"/>
            <author fullname="J. Arkko" initials="J" surname="Arkko"/>
            <date month="July" year="2011"/>
            <abstract>
              <t indent="0">This document specifies Mobile IPv6, a protocol that allows nodes to remain reachable while moving around in the IPv6 Internet.  Each mobile node is always identified by its home address, regardless of its current point of attachment to the Internet.  While situated away from its home, a mobile node is also associated with a care-of address, which provides information about the mobile node's current location.  IPv6 packets addressed to a mobile node's home address are transparently routed to its care-of address.  The protocol enables IPv6 nodes to cache the binding of a mobile node's home address with its care-of address, and to then send any packets destined for the mobile node directly to it at this document.</t>
<t>This care-of address.  To support this operation, Mobile IPv6 defines a new IPv6 protocol and a new destination option.  All IPv6 nodes, whether mobile or stationary, can communicate with mobile nodes.  This document borrows some text obsoletes RFC 3775. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6275"/>
          <seriesInfo name="DOI" value="10.17487/RFC6275"/>
        </reference>
        <reference anchor="RFC6398" target="https://www.rfc-editor.org/info/rfc6398" quoteTitle="true" derivedAnchor="RFC6398">
          <front>
            <title>IP Router Alert Considerations and analysis from <xref target="RFC7126"/>, authored by Fernando Gont, Randall Atkinson, and Carlos Pignataro.</t>

<t>The authors would like Usage</title>
            <author fullname="F. Le Faucheur" initials="F" role="editor" surname="Le Faucheur"/>
            <date month="October" year="2011"/>
            <abstract>
              <t indent="0">The IP Router Alert Option is an IP option that alerts transit routers to thank Warren Kumari more closely examine the contents of an IP packet.  The Resource reSerVation Protocol (RSVP), Pragmatic General Multicast (PGM), the Internet Group Management Protocol (IGMP), Multicast Listener Discovery (MLD), Multicast Router Discovery (MRD), and Eric Vyncke General Internet Signaling Transport (GIST) are some of the protocols that make use of the IP Router Alert Option.  This document discusses security aspects and usage guidelines around the use of the current IP Router Alert Option, thereby updating RFC 2113 and RFC 2711.  Specifically, it provides recommendations against using the Router Alert in the end-to-end open Internet and identifies controlled environments where protocols depending on Router Alert can be used safely.  It also provides recommendations about protection approaches for service providers.  Finally, it provides brief guidelines for Router Alert implementation on routers.  This memo documents an Internet Best Current Practice.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="168"/>
          <seriesInfo name="RFC" value="6398"/>
          <seriesInfo name="DOI" value="10.17487/RFC6398"/>
        </reference>
        <reference anchor="RFC6550" target="https://www.rfc-editor.org/info/rfc6550" quoteTitle="true" derivedAnchor="RFC6550">
          <front>
            <title>RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks</title>
            <author fullname="T. Winter" initials="T" role="editor" surname="Winter"/>
            <author fullname="P. Thubert" initials="P" role="editor" surname="Thubert"/>
            <author fullname="A. Brandt" initials="A" surname="Brandt"/>
            <author fullname="J. Hui" initials="J" surname="Hui"/>
            <author fullname="R. Kelsey" initials="R" surname="Kelsey"/>
            <author fullname="P. Levis" initials="P" surname="Levis"/>
            <author fullname="K. Pister" initials="K" surname="Pister"/>
            <author fullname="R. Struik" initials="R" surname="Struik"/>
            <author fullname="JP. Vasseur" initials="JP" surname="Vasseur"/>
            <author fullname="R. Alexander" initials="R" surname="Alexander"/>
            <date month="March" year="2012"/>
            <abstract>
              <t indent="0">Low-Power and Lossy Networks (LLNs) are a class of network in which both the routers and their guidance during interconnect are constrained.  LLN routers typically operate with constraints on processing power, memory, and energy (battery power).  Their interconnects are characterized by high loss rates, low data rates, and instability.  LLNs are comprised of anything from a few dozen to thousands of routers.  Supported traffic flows include point-to-point (between devices inside the publication process LLN), point-to-multipoint (from a central control point to a subset of this document.</t>

<t>Fernando would devices inside the LLN), and multipoint-to-point (from devices inside the LLN towards a central control point).  This document specifies the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL), which provides a mechanism whereby multipoint-to-point traffic from devices inside the LLN towards a central control point as well as point-to-multipoint traffic from the central control point to the devices inside the LLN are supported.  Support for point-to-point traffic is also like available. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6550"/>
          <seriesInfo name="DOI" value="10.17487/RFC6550"/>
        </reference>
        <reference anchor="RFC6553" target="https://www.rfc-editor.org/info/rfc6553" quoteTitle="true" derivedAnchor="RFC6553">
          <front>
            <title>The Routing Protocol for Low-Power and Lossy Networks (RPL) Option for Carrying RPL Information in Data-Plane Datagrams</title>
            <author fullname="J. Hui" initials="J" surname="Hui"/>
            <author fullname="JP. Vasseur" initials="JP" surname="Vasseur"/>
            <date month="March" year="2012"/>
            <abstract>
              <t indent="0">The Routing Protocol for Low-Power and Lossy Networks (RPL) includes routing information in data-plane datagrams to thank Brian Carpenter quickly identify inconsistencies in the routing topology.  This document describes the RPL Option for use among RPL routers to include such routing information. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6553"/>
          <seriesInfo name="DOI" value="10.17487/RFC6553"/>
        </reference>
        <reference anchor="RFC6554" target="https://www.rfc-editor.org/info/rfc6554" quoteTitle="true" derivedAnchor="RFC6554">
          <front>
            <title>An IPv6 Routing Header for Source Routes with the Routing Protocol for Low-Power and Ran Atkinson who, over Lossy Networks (RPL)</title>
            <author fullname="J. Hui" initials="J" surname="Hui"/>
            <author fullname="JP. Vasseur" initials="JP" surname="Vasseur"/>
            <author fullname="D. Culler" initials="D" surname="Culler"/>
            <author fullname="V. Manral" initials="V" surname="Manral"/>
            <date month="March" year="2012"/>
            <abstract>
              <t indent="0">In Low-Power and Lossy Networks (LLNs), memory constraints on routers may limit them to maintaining, at most, a few routes.  In some configurations, it is necessary to use these memory-constrained routers to deliver datagrams to nodes within the years, have answered many questions LLN.  The Routing Protocol for Low-Power and provided valuable comments Lossy Networks (RPL) can be used in some deployments to store most, if not all, routes on one (e.g., the Directed Acyclic Graph (DAG) root) or a few routers and forward the IPv6 datagram using a source routing technique to avoid large routing tables on memory-constrained routers.  This document specifies a new IPv6 Routing header type for delivering datagrams within a RPL routing domain. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6554"/>
          <seriesInfo name="DOI" value="10.17487/RFC6554"/>
        </reference>
        <reference anchor="RFC6621" target="https://www.rfc-editor.org/info/rfc6621" quoteTitle="true" derivedAnchor="RFC6621">
          <front>
            <title>Simplified Multicast Forwarding</title>
            <author fullname="J. Macker" initials="J" role="editor" surname="Macker"/>
            <date month="May" year="2012"/>
            <abstract>
              <t indent="0">This document describes a Simplified Multicast Forwarding (SMF) mechanism that have benefited his protocol-related provides basic Internet Protocol (IP) multicast forwarding suitable for limited wireless mesh and mobile ad hoc network (MANET) use.  It is mainly applicable in situations where efficient flooding represents an acceptable engineering design trade-off.  It defines techniques for multicast duplicate packet detection (DPD), to be applied in the forwarding process, for both IPv4 and IPv6 protocol use.  This document also specifies optional mechanisms for using reduced relay sets to achieve more efficient multicast data distribution within a mesh topology as compared to Classic Flooding.  Interactions with other protocols, such as use of information provided by concurrently running unicast routing protocols or interaction with other multicast protocols, as well as multiple deployment approaches are also described.  Distributed algorithms for selecting reduced relay sets and related discussion are provided in the appendices.  Basic issues relating to the operation of multicast MANET border routers are discussed, but ongoing work (including remains in this area and is beyond the present document).</t>
</section>

</middle>

<back>
<references title="Normative References">
    <?rfc include="reference.RFC.1034" ?>
    <?rfc include="reference.RFC.5570" ?>
    <?rfc include="reference.RFC.2119" ?>
    <?rfc include="reference.RFC.8174" ?>

    <?rfc include="reference.RFC.2205" ?>

    <?rfc include="reference.RFC.2675" ?>
    <?rfc include="reference.RFC.4301" ?>
    <?rfc include="reference.RFC.4302" ?>
    <?rfc include="reference.RFC.4303" ?>

    <?rfc include="reference.RFC.6275" ?>
    <?rfc include="reference.RFC.7401" ?>
    <?rfc include="reference.RFC.5533" ?>
    <?rfc include="reference.RFC.3692" ?>
    <?rfc include="reference.RFC.4727" ?>
    <?rfc include="reference.RFC.2710" ?>
    <?rfc include="reference.RFC.3810" ?>
    <?rfc include="reference.RFC.4286" ?>
    <?rfc include="reference.RFC.5971" ?>
    <?rfc include="reference.RFC.2711" ?>
    <?rfc include="reference.RFC.5095" ?>
    <?rfc include="reference.RFC.6550" ?>
    <?rfc include="reference.RFC.6621" ?>
    <?rfc include="reference.RFC.6971" ?>
    <?rfc include="reference.RFC.7045" ?>
    <?rfc include="reference.RFC.7112" ?>
    <?rfc include="reference.RFC.4782" ?>
    <?rfc include="reference.RFC.6788" ?>
    <?rfc include="reference.RFC.6740" ?>
    <?rfc include="reference.RFC.6744" ?>
    <?rfc include="reference.RFC.2473" ?>
    <?rfc include="reference.RFC.6553" ?>
    <?rfc include="reference.RFC.6554" ?>
    <?rfc include="reference.RFC.6398" ?>
    <?rfc include="reference.RFC.8754" ?>

    <?rfc include="reference.RFC.9008" ?>

    <?rfc include="reference.RFC.7731" ?>
    <?rfc include="reference.RFC.8200" ?>
    <?rfc include="reference.RFC.8250" ?>
    <?rfc include="reference.RFC.8900" ?>
</references>

<references title="Informative References">
    <?rfc include="reference.RFC.2460" ?>
    <?rfc include="reference.RFC.3871" ?>
    <?rfc include="reference.RFC.6192" ?>
    <?rfc include="reference.RFC.7126" ?>
    <?rfc include="reference.RFC.7739" ?>

    <?rfc include="reference.I-D.irtf-pearg-numeric-ids-generation" ?>

    <?rfc include="reference.RFC.9098" ?>

    <?rfc include="reference.RFC.7872" ?>

    <?rfc include="reference.I-D.vyncke-v6ops-james" ?> scope of this document.  This document defines an Experimental Protocol for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6621"/>
          <seriesInfo name="DOI" value="10.17487/RFC6621"/>
        </reference>
        <reference anchor="Huston-2022" target="https://iepg.org/2022-03-20-ietf113/huston-v6frag.pdf"> anchor="RFC6740" target="https://www.rfc-editor.org/info/rfc6740" quoteTitle="true" derivedAnchor="RFC6740">
          <front>
          <title>IPv6 Fragmentation
            <title>Identifier-Locator Network Protocol (ILNP) Architectural Description</title>
            <author fullname="RJ Atkinson" initials="RJ" surname="Atkinson"/>
            <author fullname="SN Bhatti" initials="SN" surname="Bhatti"/>
            <date month="November" year="2012"/>
            <abstract>
              <t indent="0">This document provides an architectural description and EH Behaviours</title> the concept of operations for the Identifier-Locator Network Protocol (ILNP), which is an experimental, evolutionary enhancement to IP.  This is a product of the IRTF Routing Research Group.  This document defines an Experimental Protocol for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6740"/>
          <seriesInfo name="DOI" value="10.17487/RFC6740"/>
        </reference>
        <reference anchor="RFC6744" target="https://www.rfc-editor.org/info/rfc6744" quoteTitle="true" derivedAnchor="RFC6744">
          <front>
            <title>IPv6 Nonce Destination Option for the Identifier-Locator Network Protocol for IPv6 (ILNPv6)</title>
            <author fullname="Geoff Huston" initials="G." surname="Huston">
      <organization abbrev="APNIC"/>
      <address>
        <email>gih@apnic.net</email>
        <uri>https://www.apnic.net</uri>
      </address>
    </author> fullname="RJ Atkinson" initials="RJ" surname="Atkinson"/>
            <author fullname="Joao Damas" initials="J." surname="Damas">
      <organization abbrev="APNIC"/>
    </author> fullname="SN Bhatti" initials="SN" surname="Bhatti"/>
            <date month="March" year="2022"/> month="November" year="2012"/>
            <abstract>
              <t indent="0">The Identifier-Locator Network Protocol (ILNP) is an experimental, evolutionary enhancement to IP.  ILNP has multiple instantiations.  This document describes an experimental Nonce Destination Option used only with ILNP for IPv6 (ILNPv6).  This document is a product of the IRTF Routing Research Group.  This document defines an Experimental Protocol for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name=""
                    value="IEPG Meeting - March 2022 @ IETF 113"/> name="RFC" value="6744"/>
          <seriesInfo name="DOI" value="10.17487/RFC6744"/>
        </reference>

<!--
        <reference anchor="Vyncke-2022" target="https://iepg.org/2022-03-20-ietf113/james-IEPG.pdf"> anchor="RFC6788" target="https://www.rfc-editor.org/info/rfc6788" quoteTitle="true" derivedAnchor="RFC6788">
          <front>
          <title>Just Another Measurement
            <title>The Line-Identification Option</title>
            <author fullname="S. Krishnan" initials="S" surname="Krishnan"/>
            <author fullname="A. Kavanagh" initials="A" surname="Kavanagh"/>
            <author fullname="B. Varga" initials="B" surname="Varga"/>
            <author fullname="S. Ooghe" initials="S" surname="Ooghe"/>
            <author fullname="E. Nordmark" initials="E" surname="Nordmark"/>
            <date month="November" year="2012"/>
            <abstract>
              <t indent="0">In Ethernet-based aggregation networks, several subscriber premises may be logically connected to the same interface of an Edge Router.  This document proposes a method for the Edge Router to identify the subscriber premises using the contents of the received Router Solicitation messages.  The applicability is limited to broadband network deployment scenarios in which multiple user ports are mapped to the same virtual interface on the Edge Router. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6788"/>
          <seriesInfo name="DOI" value="10.17487/RFC6788"/>
        </reference>
        <reference anchor="RFC6971" target="https://www.rfc-editor.org/info/rfc6971" quoteTitle="true" derivedAnchor="RFC6971">
          <front>
            <title>Depth-First Forwarding (DFF) in Unreliable Networks</title>
            <author fullname="U. Herberg" initials="U" role="editor" surname="Herberg"/>
            <author fullname="A. Cardenas" initials="A" surname="Cardenas"/>
            <author fullname="T. Iwao" initials="T" surname="Iwao"/>
            <author fullname="M. Dow" initials="M" surname="Dow"/>
            <author fullname="S. Cespedes" initials="S" surname="Cespedes"/>
            <date month="June" year="2013"/>
            <abstract>
              <t indent="0">This document specifies the Depth-First Forwarding (DFF) protocol for IPv6 networks, a data-forwarding mechanism that can increase reliability of data delivery in networks with dynamic topology and/or lossy links.  The protocol operates entirely on the forwarding plane but may interact with the routing plane.  DFF forwards data packets using a mechanism similar to a "depth-first search" for the destination of a packet.  The routing plane may be informed of failures to deliver a packet or loops.  This document specifies the DFF mechanism both for IPv6 networks (as specified in RFC 2460) and for "mesh-under" Low-Power Wireless Personal Area Networks (LoWPANs), as specified in RFC 4944.  The design of DFF assumes that the underlying link layer provides means to detect if a packet has been successfully delivered to the Next Hop or not.  It is applicable for networks with little traffic and is used for unicast transmissions only.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6971"/>
          <seriesInfo name="DOI" value="10.17487/RFC6971"/>
        </reference>
        <reference anchor="RFC7045" target="https://www.rfc-editor.org/info/rfc7045" quoteTitle="true" derivedAnchor="RFC7045">
          <front>
            <title>Transmission and Processing of IPv6 Extension Headers</title>
            <author fullname="B. Carpenter" initials="B" surname="Carpenter"/>
            <author fullname="S. Jiang" initials="S" surname="Jiang"/>
            <date month="December" year="2013"/>
            <abstract>
              <t indent="0">Various IPv6 extension headers have been standardised since the IPv6 standard was first published.  This document updates RFC 2460 to clarify how intermediate nodes should deal with such extension headers and with any that are defined in the future.  It also specifies how extension headers should be registered by IANA, with a corresponding minor update to RFC 2780.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7045"/>
          <seriesInfo name="DOI" value="10.17487/RFC7045"/>
        </reference>
        <reference anchor="RFC7112" target="https://www.rfc-editor.org/info/rfc7112" quoteTitle="true" derivedAnchor="RFC7112">
          <front>
            <title>Implications of Oversized IPv6 Header Survivability (JAMES)</title> Chains</title>
            <author fullname="Eric Vyncke" initials="E." surname="Vyncke">

    </author> fullname="F. Gont" initials="F" surname="Gont"/>
            <author fullname="Raphael Leas" initials="R." surname="Leas">
      <organization/>
    </author> fullname="V. Manral" initials="V" surname="Manral"/>
            <author fullname="Justin Iurman" initials="J." surname="Iurman">
      <organization/>
    </author> fullname="R. Bonica" initials="R" surname="Bonica"/>
            <date month="March" year="2022"/> month="January" year="2014"/>
            <abstract>
              <t indent="0">The IPv6 specification allows IPv6 Header Chains of an arbitrary size.  The specification also allows options that can, in turn, extend each of the headers.  In those scenarios in which the IPv6 Header Chain or options are unusually long and packets are fragmented, or scenarios in which the fragment size is very small, the First Fragment of a packet may fail to include the entire IPv6 Header Chain.  This document discusses the interoperability and security problems of such traffic, and updates RFC 2460 such that the First Fragment of a packet is required to contain the entire IPv6 Header Chain.</t>
            </abstract>
          </front>
          <seriesInfo name=""
                    value="IEPG Meeting - March 2022 @ IETF 113"/> name="RFC" value="7112"/>
          <seriesInfo name="DOI" value="10.17487/RFC7112"/>
        </reference>
-->
        <reference anchor="draft-ietf-nimrod-eid"> anchor="RFC7401" target="https://www.rfc-editor.org/info/rfc7401" quoteTitle="true" derivedAnchor="RFC7401">
          <front>
          <title>Endpoint Identifier
            <title>Host Identity Protocol Version 2 (HIPv2)</title>
            <author fullname="R. Moskowitz" initials="R" role="editor" surname="Moskowitz"/>
            <author fullname="T. Heer" initials="T" surname="Heer"/>
            <author fullname="P. Jokela" initials="P" surname="Jokela"/>
            <author fullname="T. Henderson" initials="T" surname="Henderson"/>
            <date month="April" year="2015"/>
            <abstract>
              <t indent="0">This document specifies the details of the Host Identity Protocol (HIP). HIP allows consenting hosts to securely establish and maintain shared IP-layer state, allowing separation of the identifier and locator roles of IP addresses, thereby enabling continuity of communications across IP address changes. HIP is based on a Diffie-Hellman key exchange, using public key identifiers from a new Host Identity namespace for mutual peer authentication. The protocol is designed to be resistant to denial-of-service (DoS) and man-in-the-middle (MitM) attacks. When used together with another suitable security protocol, such as the Encapsulating Security Payload (ESP), it provides integrity protection and optional encryption for upper-layer protocols, such as TCP and UDP.</t>
              <t indent="0">This document obsoletes RFC 5201 and addresses the concerns raised by the IESG, particularly that of crypto agility. It also incorporates lessons learned from the implementations of RFC 5201.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7401"/>
          <seriesInfo name="DOI" value="10.17487/RFC7401"/>
        </reference>
        <reference anchor="RFC7731" target="https://www.rfc-editor.org/info/rfc7731" quoteTitle="true" derivedAnchor="RFC7731">
          <front>
            <title>Multicast Protocol for Low-Power and Lossy Networks (MPL)</title>
            <author fullname="J. Hui" initials="J" surname="Hui"/>
            <author fullname="R. Kelsey" initials="R" surname="Kelsey"/>
            <date month="February" year="2016"/>
            <abstract>
              <t indent="0">This document specifies the Multicast Protocol for Low-Power and Lossy Networks (MPL), which provides IPv6 multicast forwarding in constrained networks. MPL avoids the need to construct or maintain any multicast forwarding topology, disseminating messages to all MPL Forwarders in an MPL Domain.</t>
              <t indent="0">MPL has two modes of operation. One mode uses the Trickle algorithm to manage control-plane and data-plane message transmissions and is applicable for deployments with few multicast sources. The other mode uses classic flooding. By providing both modes and parameterization of the Trickle algorithm, an MPL implementation can be used in a variety of multicast deployments and can trade between dissemination latency and transmission efficiency.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7731"/>
          <seriesInfo name="DOI" value="10.17487/RFC7731"/>
        </reference>
        <reference anchor="RFC8174" target="https://www.rfc-editor.org/info/rfc8174" quoteTitle="true" derivedAnchor="RFC8174">
          <front>
            <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
            <author fullname="B. Leiba" initials="B" surname="Leiba"/>
            <date month="May" year="2017"/>
            <abstract>
              <t indent="0">RFC 2119 specifies common key words that may be used in protocol specifications.  This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="14"/>
          <seriesInfo name="RFC" value="8174"/>
          <seriesInfo name="DOI" value="10.17487/RFC8174"/>
        </reference>
        <reference anchor="RFC8200" target="https://www.rfc-editor.org/info/rfc8200" quoteTitle="true" derivedAnchor="RFC8200">
          <front>
            <title>Internet Protocol, Version 6 (IPv6) Specification</title>
            <author fullname="S. Deering" initials="S" surname="Deering"/>
            <author fullname="R. Hinden" initials="R" surname="Hinden"/>
            <date month="July" year="2017"/>
            <abstract>
              <t indent="0">This document specifies version 6 of the Internet Protocol (IPv6).  It obsoletes RFC 2460.</t>
            </abstract>
          </front>
          <seriesInfo name="STD" value="86"/>
          <seriesInfo name="RFC" value="8200"/>
          <seriesInfo name="DOI" value="10.17487/RFC8200"/>
        </reference>
        <reference anchor="RFC8250" target="https://www.rfc-editor.org/info/rfc8250" quoteTitle="true" derivedAnchor="RFC8250">
          <front>
            <title>IPv6 Performance and Diagnostic Metrics (PDM) Destination Option</title>
            <author fullname="Charles Lynn" initials="C.L." surname="Lynn">
            <organization>BBN Systems fullname="N. Elkins" initials="N" surname="Elkins"/>
            <author fullname="R. Hamilton" initials="R" surname="Hamilton"/>
            <author fullname="M. Ackermann" initials="M" surname="Ackermann"/>
            <date month="September" year="2017"/>
            <abstract>
              <t indent="0">To assess performance problems, this document describes optional headers embedded in each packet that provide sequence numbers and Technologies</organization>
          </author> timing information as a basis for measurements.  Such measurements may be interpreted in real time or after the fact.  This document specifies the Performance and Diagnostic Metrics (PDM) Destination Options header.  The field limits, calculations, and usage in measurement of PDM are included in this document.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="8250"/>
          <seriesInfo name="DOI" value="10.17487/RFC8250"/>
        </reference>
        <reference anchor="RFC8754" target="https://www.rfc-editor.org/info/rfc8754" quoteTitle="true" derivedAnchor="RFC8754">
          <front>
            <title>IPv6 Segment Routing Header (SRH)</title>
            <author fullname="C. Filsfils" initials="C" role="editor" surname="Filsfils"/>
            <author fullname="D. Dukes" initials="D" role="editor" surname="Dukes"/>
            <author fullname="S. Previdi" initials="S" surname="Previdi"/>
            <author fullname="J. Leddy" initials="J" surname="Leddy"/>
            <author fullname="S. Matsushima" initials="S" surname="Matsushima"/>
            <author fullname="D. Voyer" initials="D" surname="Voyer"/>
            <date month="November" year="1995"/> month="March" year="2020"/>
            <abstract>
              <t indent="0">Segment Routing can be applied to the IPv6 data plane using a new type of Routing Extension Header called the Segment Routing Header (SRH).  This document describes the SRH and how it is used by nodes that are Segment Routing (SR) capable.</t>
            </abstract>
          </front>
          <seriesInfo name=""
                    value="IETF name="RFC" value="8754"/>
          <seriesInfo name="DOI" value="10.17487/RFC8754"/>
        </reference>
        <reference anchor="RFC8900" target="https://www.rfc-editor.org/info/rfc8900" quoteTitle="true" derivedAnchor="RFC8900">
          <front>
            <title>IP Fragmentation Considered Fragile</title>
            <author fullname="R. Bonica" initials="R" surname="Bonica"/>
            <author fullname="F. Baker" initials="F" surname="Baker"/>
            <author fullname="G. Huston" initials="G" surname="Huston"/>
            <author fullname="R. Hinden" initials="R" surname="Hinden"/>
            <author fullname="O. Troan" initials="O" surname="Troan"/>
            <author fullname="F. Gont" initials="F" surname="Gont"/>
            <date month="September" year="2020"/>
            <abstract>
              <t indent="0">This document describes IP fragmentation and explains how it introduces fragility to Internet Draft, draft-ietf-nimrod-eid-00.txt"/> communication.</t>
              <t indent="0">This document also proposes alternatives to IP fragmentation and provides recommendations for developers and network operators.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="230"/>
          <seriesInfo name="RFC" value="8900"/>
          <seriesInfo name="DOI" value="10.17487/RFC8900"/>
        </reference>
        <reference anchor="NIMROD-DOC"> anchor="RFC9008" target="https://www.rfc-editor.org/info/rfc9008" quoteTitle="true" derivedAnchor="RFC9008">
          <front>
			<title>http://ana-3.lcs.mit.edu/~jnc/nimrod/</title>
            <title>Using RPI Option Type, Routing Header for Source Routes, and IPv6-in-IPv6 Encapsulation in the RPL Data Plane</title>
            <author initials="" surname="Nimrod Documentation Page" fullname="Nimrod Documentation Page">
				<organization></organization> initials="M.I." surname="Robles" fullname="M.I. Robles">
              <organization showOnFrontPage="true"/>
            </author>
            <author initials="M." surname="Richardson" fullname="M. Richardson">
              <organization showOnFrontPage="true"/>
            </author>
            <author initials="P." surname="Thubert" fullname="P. Thubert">
              <organization showOnFrontPage="true"/>
            </author>
            <date year=""/> year="2021" month="April"/>
            <abstract>
              <t indent="0">This document looks at different data flows through Low-Power and Lossy Networks (LLN) where RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) is used to establish routing. The document enumerates the cases where RPL Packet Information (RPI) Option Type (RFC 6553), RPL Source Route Header (RFC 6554), and IPv6-in-IPv6 encapsulation are required in the data plane. This analysis provides the basis upon which to design efficient compression of these headers. This document updates RFC 6553 by adding a change to the RPI Option Type. Additionally, this document updates RFC 6550 by defining a flag in the DODAG Information Object (DIO) Configuration option to indicate this change and updates RFC 8138 as well to consider the new Option Type when the RPL Option is decompressed.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="9008"/>
          <seriesInfo name="DOI" value="10.17487/RFC9008"/>
        </reference>
      </references>
      <references pn="section-8.2">
        <name slugifiedName="name-informative-references">Informative References</name>
        <reference anchor="Biondi2007" target="http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf"> anchor="Biondi-2007" target="http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf" quoteTitle="true" derivedAnchor="Biondi-2007">
          <front>
            <title>IPv6 Routing Header Security</title>
            <author fullname="P. Biondi" initials="P." surname="Biondi">
            <organization/>
              <organization showOnFrontPage="true"/>
            </author>
            <author fullname="A. Ebalard" initials="A." surname="Ebalard">
            <organization/>
              <organization showOnFrontPage="true"/>
            </author>
            <date month="April" year="2007"/>
          </front>

        <seriesInfo name="CanSecWest 2007"
                    value="Security Conference"/>
      </reference>

      <reference anchor="IANA-PROTOCOLS"
                 target="https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml">
        <front>
          <title>Protocol Numbers</title>

          <author fullname="">
            <organization>Internet Assigned Numbers Authority</organization>
          </author>

          <date year="2014"/>
        </front>

        <format target="https://www.iana.org/assignments/protocol-numbers/protocol-numbers.txt"
                type="TXT"/>
          <refcontent>CanSecWest Security Conference</refcontent>
        </reference>
        <reference anchor="IANA-IPV6-PARAM"
                 target="https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml"> anchor="Cisco-EH" target="https://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd8054d37d.pdf" quoteTitle="true" derivedAnchor="Cisco-EH">
          <front>
          <title>Internet Protocol Version 6 (IPv6) Parameters</title>
            <title abbrev="Cisco IPv6 EH">IPv6 Extension Headers Review and Considerations</title>
            <author initials="" surname="" fullname="">
            <organization>Internet Assigned Numbers Authority</organization>
              <organization showOnFrontPage="true">Cisco Systems</organization>
            </author>
            <date month="December" year="2013"/> month="October" year="2006"/>
          </front>
          <refcontent>Whitepaper</refcontent>
        </reference>
        <reference anchor="FW-Benchmark" target="https://www.ipv6hackers.org/files/meetings/ipv6-hackers-1/zack-ipv6hackers1-firewall-security-assessment-and-benchmarking.pdf"> target="https://www.ipv6hackers.org/files/meetings/ipv6-hackers-1/zack-ipv6hackers1-firewall-security-assessment-and-benchmarking.pdf" quoteTitle="true" derivedAnchor="FW-Benchmark">
          <front>
            <title abbrev="Firewall Benchmarking">Firewall Security Assessment and Benchmarking IPv6 Firewall Load Tests</title>
            <author initials="E." surname="Zack" fullname="Eldad Zack">
  </author>
            <date year=""/> month="June" year="2013"/>
          </front>
		<seriesInfo name="" value="IPv6
          <refcontent>IPv6 Hackers Meeting #1, Berlin, Germany. June 30, 2013"/>
<!-- July 27 - August 1 --> Germany</refcontent>
        </reference>
        <reference anchor="Cisco-EH" target="https://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd8054d37d.pdf"> anchor="Huston-2022" target="https://iepg.org/2022-03-20-ietf113/huston-v6frag.pdf" quoteTitle="true" derivedAnchor="Huston-2022">
          <front>
  <title abbrev="Cisco IPv6 EH">IPv6 Extension Headers Review
            <title>IPv6 Fragmentation and Considerations</title> EH Behaviours</title>
            <author initials="" surname="Cisco Systems" fullname="Cisco Systems"> fullname="Geoff Huston" initials="G." surname="Huston">
              <organization abbrev="APNIC" showOnFrontPage="true"/>
              <address>
                <email>gih@apnic.net</email>
                <uri>https://www.apnic.net</uri>
              </address>
            </author>
            <author fullname="Joao Damas" initials="J." surname="Damas">
              <organization abbrev="APNIC" showOnFrontPage="true"/>
            </author>
            <date year=""/> month="March" year="2022"/>
          </front>
		<seriesInfo name="" value="Whitepaper. October 2006"/>
<!-- July 27 - August 1 -->
          <refcontent>IEPG Meeting at IETF 113"</refcontent>
        </reference>
        <reference anchor="draft-gont-6man-ipv6-opt-transmit"> anchor="IANA-IPV6-PARAM" target="https://www.iana.org/assignments/ipv6-parameters" quoteTitle="true" derivedAnchor="IANA-IPV6-PARAM">
          <front>
            <title>Internet Protocol Version 6 (IPv6) Parameters</title>
            <author>
              <organization showOnFrontPage="true">IANA</organization>
            </author>
          </front>
        </reference>
        <reference anchor="IANA-PROTOCOLS" target="https://www.iana.org/assignments/protocol-numbers" quoteTitle="true" derivedAnchor="IANA-PROTOCOLS">
          <front>
            <title>Protocol Numbers</title>
            <author>
              <organization showOnFrontPage="true">IANA</organization>
            </author>
          </front>
        </reference>
        <reference anchor="I-D.gont-6man-ipv6-opt-transmit" quoteTitle="true" target="https://datatracker.ietf.org/doc/html/draft-gont-6man-ipv6-opt-transmit-02" derivedAnchor="IPv6-OPTIONS">
          <front>
            <title>Transmission and Processing of IPv6 Options</title>
            <author fullname="Fernando Gont" initials="F." surname="Gont">
            <organization>SI6 Networks / UTN-FRH</organization> Gont">
	 </author>
            <author fullname="Will Liu" initials="W." surname="Liu">
            <organization></organization> fullname="Will(Shucheng) Liu">
	 </author>
            <author fullname="Ron Bonica" initials="R." surname="Bonica">
            <organization></organization> fullname="Ronald P. Bonica">
	 </author>
            <date month="August" day="21" year="2015"/>
            <abstract>
              <t indent="0">   Various IPv6 options have been standardized since the core IPv6
   standard was first published.  This document updates RFC 2460 to
   clarify how nodes should deal with such IPv6 options and with any
   options that are defined in the future.  It complements [RFC7045],
   which offers a similar clarification regarding IPv6 Extension
   Headers.

              </t>
            </abstract>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-gont-6man-ipv6-opt-transmit-02"/>
          <format type="TXT" target="https://www.ietf.org/archive/id/draft-gont-6man-ipv6-opt-transmit-02.txt"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
        <reference anchor="I-D.vyncke-v6ops-james" quoteTitle="true" target="https://datatracker.ietf.org/doc/html/draft-vyncke-v6ops-james-02" derivedAnchor="JAMES">
          <front>
            <title>Just Another Measurement of Extension header Survivability (JAMES)</title>
            <author fullname="Justin Iurman">
	 </author>
            <date month="July" day="11" year="2022"/>
            <abstract>
              <t indent="0">   In 2016, RFC7872 has measured the drop of packets with IPv6 extension
   headers.  This document presents a slightly different methodology
   with more recent results.  It is still work in progress.

              </t>
            </abstract>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-vyncke-v6ops-james-02"/>
          <format type="TXT" target="https://www.ietf.org/archive/id/draft-vyncke-v6ops-james-02.txt"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
        <reference anchor="NIMROD-DOC" target="http://ana-3.lcs.mit.edu/~jnc/nimrod" quoteTitle="true" derivedAnchor="NIMROD-DOC">
          <front>
            <title>Nimrod Documentation</title>
            <author/>
          </front>
        </reference>
        <reference anchor="NIMROD-EID" quoteTitle="true" target="https://datatracker.ietf.org/doc/html/draft-ietf-nimrod-eid-00" derivedAnchor="NIMROD-EID">
          <front>
            <title>Endpoint Identifier Destination Option</title>
            <author initials="C." surname="Lynn" fullname="Dr. Charles W. Lynn Jr.">
         </author>
            <date month="March" day="2" year="1996"/>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-ietf-nimrod-eid-00"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
        <reference anchor="I-D.irtf-pearg-numeric-ids-generation" quoteTitle="true" target="https://datatracker.ietf.org/doc/html/draft-irtf-pearg-numeric-ids-generation-11" derivedAnchor="NUMERIC-IDS">
          <front>
            <title>On the Generation of Transient Numeric Identifiers</title>
            <author fullname="Fernando Gont">
              <organization showOnFrontPage="true">SI6 Networks</organization>
            </author>
            <author fullname="Ivan Arce">
              <organization showOnFrontPage="true">Quarkslab</organization>
            </author>
            <date month="July" day="11" year="2022"/>
            <abstract>
              <t indent="0">   This document performs an analysis of the security and privacy
   implications of different types of "transient numeric identifiers"
   used in IETF protocols, and tries to categorize them based on their
   interoperability requirements and their associated failure severity
   when such requirements are not met.  Subsequently, it provides advice
   on possible algorithms that could be employed to satisfy the
   interoperability requirements of each identifier category, while
   minimizing the negative security and privacy implications, thus
   providing guidance to protocol designers and protocol implementers.
   Finally, it describes a number of algorithms that have been employed
   in real implementations to generate transient numeric identifiers,
   and analyzes their security and privacy properties.  This document is
   a product of the Privacy Enhancement and Assessment Research Group
   (PEARG) in the IRTF.

              </t>
            </abstract>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-irtf-pearg-numeric-ids-generation-11"/>
          <format type="TXT" target="https://www.ietf.org/archive/id/draft-irtf-pearg-numeric-ids-generation-11.txt"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
        <reference anchor="RFC2460" target="https://www.rfc-editor.org/info/rfc2460" quoteTitle="true" derivedAnchor="RFC2460">
          <front>
            <title>Internet Protocol, Version 6 (IPv6) Specification</title>
            <author fullname="S. Deering" initials="S" surname="Deering"/>
            <author fullname="R. Hinden" initials="R" surname="Hinden"/>
            <date month="December" year="1998"/>
            <abstract>
              <t indent="0">This document specifies version 6 of the Internet Protocol (IPv6), also sometimes referred to as IP Next Generation or IPng. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2460"/>
          <seriesInfo name="DOI" value="10.17487/RFC2460"/>
        </reference>
        <reference anchor="RFC3871" target="https://www.rfc-editor.org/info/rfc3871" quoteTitle="true" derivedAnchor="RFC3871">
          <front>
            <title>Operational Security Requirements for Large Internet Service Provider (ISP) IP Network Infrastructure</title>
            <author fullname="G. Jones" initials="G" role="editor" surname="Jones"/>
            <date month="September" year="2004"/>
            <abstract>
              <t indent="0">This document defines a list of operational security requirements for the infrastructure of large Internet Service Provider (ISP) IP networks (routers and switches).  A framework is defined for specifying "profiles", which are collections of requirements applicable to certain network topology contexts (all, core-only, edge-only...).  The goal is to provide network operators a clear, concise way of communicating their security requirements to vendors.  This memo provides information for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="3871"/>
          <seriesInfo name="DOI" value="10.17487/RFC3871"/>
        </reference>
        <reference anchor="RFC6192" target="https://www.rfc-editor.org/info/rfc6192" quoteTitle="true" derivedAnchor="RFC6192">
          <front>
            <title>Protecting the Router Control Plane</title>
            <author fullname="D. Dugal" initials="D" surname="Dugal"/>
            <author fullname="C. Pignataro" initials="C" surname="Pignataro"/>
            <author fullname="R. Dunn" initials="R" surname="Dunn"/>
            <date month="March" year="2011"/>
            <abstract>
              <t indent="0">This memo provides a method for protecting a router's control plane from undesired or malicious traffic. In this approach, all legitimate router control plane traffic is identified. Once legitimate traffic has been identified, a filter is deployed in the router's forwarding plane. That filter prevents traffic not specifically identified as legitimate from reaching the router's control plane, or rate-limits such traffic to an acceptable level.</t>
              <t indent="0">Note that the filters described in this memo are applied only to traffic that is destined for the router, and not to all traffic that is passing through the router. This document is not an Internet Standards Track specification; it is published for informational purposes.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6192"/>
          <seriesInfo name="DOI" value="10.17487/RFC6192"/>
        </reference>
        <reference anchor="RFC7126" target="https://www.rfc-editor.org/info/rfc7126" quoteTitle="true" derivedAnchor="RFC7126">
          <front>
            <title>Recommendations on Filtering of IPv4 Packets Containing IPv4 Options</title>
            <author fullname="F. Gont" initials="F" surname="Gont"/>
            <author fullname="R. Atkinson" initials="R" surname="Atkinson"/>
            <author fullname="C. Pignataro" initials="C" surname="Pignataro"/>
            <date month="February" year="2014"/>
            <abstract>
              <t indent="0">This document provides advice on the filtering of IPv4 packets based on the IPv4 options they contain.  Additionally, it discusses the operational and interoperability implications of dropping packets based on the IP options they contain.</t>
            </abstract>
          </front>
          <seriesInfo name=""
                    value="IETF name="BCP" value="186"/>
          <seriesInfo name="RFC" value="7126"/>
          <seriesInfo name="DOI" value="10.17487/RFC7126"/>
        </reference>
        <reference anchor="RFC7739" target="https://www.rfc-editor.org/info/rfc7739" quoteTitle="true" derivedAnchor="RFC7739">
          <front>
            <title>Security Implications of Predictable Fragment Identification Values</title>
            <author fullname="F. Gont" initials="F" surname="Gont"/>
            <date month="February" year="2016"/>
            <abstract>
              <t indent="0">IPv6 specifies the Fragment Header, which is employed for the fragmentation and reassembly mechanisms.  The Fragment Header contains an "Identification" field that, together with the IPv6 Source Address and the IPv6 Destination Address of a packet, identifies fragments that correspond to the same original datagram, such that they can be reassembled together by the receiving host.  The only requirement for setting the Identification field is that the corresponding value must be different than that employed for any other fragmented datagram sent recently with the same Source Address and Destination Address.  Some implementations use a simple global counter for setting the Identification field, thus leading to predictable Identification values.  This document analyzes the security implications of predictable Identification values, and provides implementation guidance for setting the Identification field of the Fragment Header, such that the aforementioned security implications are mitigated.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7739"/>
          <seriesInfo name="DOI" value="10.17487/RFC7739"/>
        </reference>
        <reference anchor="RFC7872" target="https://www.rfc-editor.org/info/rfc7872" quoteTitle="true" derivedAnchor="RFC7872">
          <front>
            <title>Observations on the Dropping of Packets with IPv6 Extension Headers in the Real World</title>
            <author fullname="F. Gont" initials="F" surname="Gont"/>
            <author fullname="J. Linkova" initials="J" surname="Linkova"/>
            <author fullname="T. Chown" initials="T" surname="Chown"/>
            <author fullname="W. Liu" initials="W" surname="Liu"/>
            <date month="June" year="2016"/>
            <abstract>
              <t indent="0">This document presents real-world data regarding the extent to which packets with IPv6 Extension Headers (EHs) are dropped in the Internet Draft, work (as originally measured in August 2014 and later in June 2015, with similar results) and where in progress"/> the network such dropping occurs.  The aforementioned results serve as a problem statement that is expected to trigger operational advice on the filtering of IPv6 packets carrying IPv6 EHs so that the situation improves over time.  This document also explains how the results were obtained, such that the corresponding measurements can be reproduced by other members of the community and repeated over time to observe changes in the handling of packets with IPv6 EHs.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7872"/>
          <seriesInfo name="DOI" value="10.17487/RFC7872"/>
        </reference>
        <reference anchor="RFC9098" target="https://www.rfc-editor.org/info/rfc9098" quoteTitle="true" derivedAnchor="RFC9098">
          <front>
            <title>Operational Implications of IPv6 Packets with Extension Headers</title>
            <author fullname="F. Gont" initials="F" surname="Gont"/>
            <author fullname="N. Hilliard" initials="N" surname="Hilliard"/>
            <author fullname="G. Doering" initials="G" surname="Doering"/>
            <author fullname="W. Kumari" initials="W" surname="Kumari"/>
            <author fullname="G. Huston" initials="G" surname="Huston"/>
            <author fullname="W. Liu" initials="W" surname="Liu"/>
            <date month="September" year="2021"/>
            <abstract>
              <t indent="0">This document summarizes the operational implications of IPv6 extension headers specified in the IPv6 protocol specification (RFC 8200) and attempts to analyze reasons why packets with IPv6 extension headers are often dropped in the public Internet.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="9098"/>
          <seriesInfo name="DOI" value="10.17487/RFC9098"/>
        </reference>
      </references>
    </references>
    <section numbered="false" toc="include" removeInRFC="false" pn="section-appendix.a">
      <name slugifiedName="name-acknowledgements">Acknowledgements</name>
      <t indent="0" pn="section-appendix.a-1">The authors would like to thank <contact fullname="Ron Bonica"/> for his work on earlier draft versions of this document.</t>
      <t indent="0" pn="section-appendix.a-2">The authors of this document would like to thank (in alphabetical order) <contact fullname="Mikael Abrahamsson"/>, <contact fullname="Brian Carpenter"/>, <contact fullname="Tim Chown"/>, <contact fullname="Roman Danyliw"/>, <contact fullname="Darren Dukes"/>, <contact fullname="Lars Eggert"/>, <contact fullname="David Farmer"/>, <contact fullname="Mike Heard"/>, <contact fullname="Bob Hinden"/>, <contact fullname="Christian Huitema"/>, <contact fullname="Benjamin Kaduk"/>, <contact fullname="Erik Kline"/>, <contact fullname="Murray Kucherawy"/>, <contact fullname="Jen Linkova"/>, <contact fullname="Carlos Pignataro"/>, <contact fullname="Alvaro Retana"/>, <contact fullname="Maria Ines Robles"/>, <contact fullname="Zaheduzzaman Sarker"/>, <contact fullname="Donald Smith"/>, <contact fullname="Pascal Thubert"/>, <contact fullname="Ole Troan"/>, <contact fullname="Gunter Van de Velde"/>, <contact fullname="Éric Vyncke"/>, and <contact fullname="Robert Wilton"/> for providing valuable comments on earlier draft versions of this document.</t>
      <t indent="0" pn="section-appendix.a-3">This document borrows some text and analysis from <xref target="RFC7126" format="default" sectionFormat="of" derivedContent="RFC7126"/>, which is authored by <contact fullname="Fernando Gont"/>, <contact fullname="Randall Atkinson"/>, and <contact fullname="Carlos Pignataro"/>.</t>
      <t indent="0" pn="section-appendix.a-4">The authors would like to thank <contact fullname="Warren Kumari"/> and <contact fullname="Éric Vyncke"/> for their guidance during the publication process for this document.</t>
      <t indent="0" pn="section-appendix.a-5">Fernando would also like to thank <contact fullname="Brian Carpenter"/> and <contact fullname="Ran Atkinson"/> who, over the years, have answered many questions and provided valuable comments that have benefited his protocol-related work (including the present document).</t>
    </section>
    <section anchor="authors-addresses" numbered="false" removeInRFC="false" toc="include" pn="section-appendix.b">
      <name slugifiedName="name-authors-addresses">Authors' Addresses</name>
      <author fullname="Fernando Gont" initials="F." surname="Gont">
        <organization abbrev="SI6 Networks" showOnFrontPage="true">SI6 Networks</organization>
        <address>
          <postal>
            <street>Segurola y Habana 4310 7mo piso</street>
            <city>Ciudad Autonoma de Buenos Aires</city>
            <country>Argentina</country>
          </postal>
          <email>fgont@si6networks.com</email>
          <uri>https://www.si6networks.com</uri>
        </address>
      </author>
      <author fullname="Will (Shucheng) Liu" initials="W." surname="Liu">
        <organization showOnFrontPage="true">Huawei Technologies</organization>
        <address>
          <postal>
            <street>Bantian, Longgang District</street>
            <city>Shenzhen</city>
            <code>518129</code>
            <country>China</country>
          </postal>
          <email>liushucheng@huawei.com</email>
        </address>
      </author>
    </section>
  </back>
</rfc>