<?xml version='1.0' encoding='utf-8'?>
<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" category="info" docName="draft-liu-lsr-p2poverlan-12" indexInclude="true" ipr="trust200902" number="9296" prepTime="2022-08-23T15:43:55" scripts="Common,Latin" sortRefs="true" submissionType="independent" symRefs="true" tocDepth="3" tocInclude="true" xml:lang="en">
  <link href="https://datatracker.ietf.org/doc/draft-liu-lsr-p2poverlan-12" rel="prev"/>
  <link href="https://dx.doi.org/10.17487/rfc9296" rel="alternate"/>
  <link href="urn:issn:2070-1721" rel="alternate"/>
  <front>
    <title abbrev="IfStackTable for P2poverLAN interface">ifStackTable for the Point-to-Point (P2P) Interface over a LAN Type: Definition and Examples</title>
    <seriesInfo name="RFC" value="9296" stream="independent"/>
    <author initials="D." surname="Liu" fullname="Daiying Liu">
      <organization showOnFrontPage="true">Ericsson</organization>
      <address>
        <postal>
          <street>No.5 Lize East Street</street>
          <code>100102</code>
          <city>Beijing</city>
          <country>China</country>
        </postal>
        <email>harold.liu@ericsson.com</email>
      </address>
    </author>
    <author initials="J." surname="Halpern" fullname="Joel Halpern">
      <organization showOnFrontPage="true">Ericsson</organization>
      <address>
        <email>joel.halpern@ericsson.com</email>
      </address>
    </author>
    <author initials="C." surname="Zhang" fullname="Congjie Zhang">
      <organization showOnFrontPage="true">Ericsson</organization>
      <address>
        <email>congjie.zhang@ericsson.com</email>
      </address>
    </author>
    <date month="08" year="2022"/>
    <abstract pn="section-abstract">
      <t indent="0" pn="section-abstract-1">RFC 5309 defines the Point-to-Point (P2P) circuit type, one of the two circuit types used in the link-state routing protocols, and
				 highlights that it is important to identify the correct circuit type when forming adjacencies, flooding 
         link-state database packets, and monitoring the link state.
      </t>
      <t indent="0" pn="section-abstract-2">
         This document provides advice about the ifStack for the P2P interface over a LAN Type
         to facilitate operational control, maintenance, and statistics. 
      </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 is a contribution to the RFC Series, independently of any
            other RFC stream.  The RFC Editor has chosen to publish this
            document at its discretion and makes no statement about its value
            for implementation or deployment.  Documents approved for
            publication by the RFC Editor are not 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/rfc9296" 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.
        </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" keepWithNext="true" 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-requirements-language">Requirements Language</xref></t>
          </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-interface-stack-table-for-p">Interface Stack Table for P2P Interface Type</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" keepWithNext="true" 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-p2p-interface-higher-layer-">P2P Interface: higher-layer-if and lower-layer-if</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-p2p-interface-statistics">P2P Interface Statistics</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-p2p-interface-administrativ">P2P Interface Administrative State</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-security-considerations">Security Considerations</xref></t>
          </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-references">References</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.6.2">
              <li pn="section-toc.1-1.6.2.1">
                <t indent="0" pn="section-toc.1-1.6.2.1.1"><xref derivedContent="6.1" format="counter" sectionFormat="of" target="section-6.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-normative-references">Normative References</xref></t>
              </li>
              <li pn="section-toc.1-1.6.2.2">
                <t indent="0" pn="section-toc.1-1.6.2.2.1"><xref derivedContent="6.2" format="counter" sectionFormat="of" target="section-6.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-informative-references">Informative References</xref></t>
              </li>
            </ul>
          </li>
          <li pn="section-toc.1-1.7">
            <t indent="0" pn="section-toc.1-1.7.1"><xref derivedContent="Appendix A" format="default" sectionFormat="of" target="section-appendix.a"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-examples">Examples</xref></t>
          </li>
          <li pn="section-toc.1-1.8">
            <t indent="0" pn="section-toc.1-1.8.1"><xref derivedContent="" format="none" sectionFormat="of" target="section-appendix.b"/><xref derivedContent="" format="title" sectionFormat="of" target="name-acknowledgements">Acknowledgements</xref></t>
          </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.c"/><xref derivedContent="" format="title" sectionFormat="of" target="name-authors-addresses">Authors' Addresses</xref></t>
          </li>
        </ul>
      </section>
    </toc>
  </front>
  <middle>
    <section numbered="true" toc="include" removeInRFC="false" pn="section-1">
      <name slugifiedName="name-introduction">Introduction</name>
      <t indent="0" pn="section-1-1"><xref target="RFC5309" format="default" sectionFormat="of" derivedContent="RFC5309"/> defines the Point-to-Point (P2P) circuit type and highlights that it is important to identify the correct circuit type when forming adjacencies, flooding link-state database packets, and monitoring the link state.
      </t>
      <t indent="0" pn="section-1-2">
      	 To simplify configuration and operational control, it is helpful
      	 to represent the fact that an interface is to be considered
      	 a P2P interface over a LAN type explicitly in the interface stack. This
      	 enables, for example, routing protocols to automatically inherit 
      	 the correct operating mode from the interface stack without further configuration (i.e., there is no need to explicitly configure the P2P interface in routing protocols).
      </t>
      <t indent="0" pn="section-1-3">It is helpful to map the P2P interface over a LAN type in the interface management stack table. If no entry specifies the lower layer of the P2P interface, then management tools lose the ability to 
      	 retrieve and measure properties specific to lower layers.
      </t>
      <t indent="0" pn="section-1-4">In standard network management protocols that make use of
  ifStackTables, the P2P interface over a LAN type is intended to be used
  solely as a means to signal that the upper-layer interface of link-data layer is a P2P interface. Thus, the upper and lower layers of P2P over a LAN type are
  expected to apply appropriate semantics.  In general, the higher layer of a P2P over a LAN type <bcp14>SHOULD</bcp14> be "ipForward" (value 142 in
   <xref target="Assignment" format="default" sectionFormat="of" derivedContent="Assignment"/>), and the lower layer of P2P over a LAN type <bcp14>SHOULD</bcp14> be any appropriate link-data layer of "ipForward".
      </t>
      <t indent="0" pn="section-1-5">The assignment of 303 as the value for the p2pOverLan ifType was made by Expert Review (see <xref target="Assignment" format="default" sectionFormat="of" derivedContent="Assignment"/> and <xref target="RFC8126" format="default" sectionFormat="of" derivedContent="RFC8126"/>).
The purpose of this document is to serve as a reference for ifType 303 by suggesting how the ifStackTable for the P2P interface over a LAN type is to be used and providing examples.
      </t>
      <t indent="0" pn="section-1-6">It should be noted that this document reflects the operating model used on some routers. Other routers that use different models may not represent a P2P as a separate interface.
      </t>
    </section>
    <section numbered="true" toc="include" removeInRFC="false" pn="section-2">
      <name slugifiedName="name-requirements-language">Requirements Language</name>
      <t indent="0" pn="section-2-1">
    The key words "<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 "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP 14 <xref 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 anchor="sec3" numbered="true" toc="include" removeInRFC="false" pn="section-3">
      <name slugifiedName="name-interface-stack-table-for-p">Interface Stack Table for P2P Interface Type</name>
      <section anchor="sec3_1" numbered="true" toc="include" removeInRFC="false" pn="section-3.1">
        <name slugifiedName="name-p2p-interface-higher-layer-">P2P Interface: higher-layer-if and lower-layer-if</name>
        <t indent="0" pn="section-3.1-1">If a device implements the IF-MIB <xref target="RFC2863" format="default" sectionFormat="of" derivedContent="RFC2863"/>, then each entry in the "/interfaces/interface" list (see "A YANG Data Model for Interface Management" <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/>) in the operational state is typically
mapped to one ifEntry as required in <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/>. Therefore, the P2P interface over a LAN type should also be fully mapped to one ifEntry by defining the "ifStackTable" ("higher-layer-if" and "lower-layer-if", defined in <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/>).
        </t>
        <t indent="0" pn="section-3.1-2">In the ifStackTable, the higher layer of the P2P interface over a LAN type <bcp14>SHALL</bcp14> be network layer "ipForward" to enable IP routing, and the lower layer of the P2P interface over a LAN type <bcp14>SHOULD</bcp14> be any link-data layer that can be bound to "ipForward", including "ethernetCsmacd", "ieee8023adLag", "l2vlan", and so on (defined in the iana-if-type YANG module <xref target="IANA-ifTYPE" format="default" sectionFormat="of" derivedContent="IANA-ifTYPE"/>).
        </t>
        <t indent="0" pn="section-3.1-3">The P2P interface over the LAN type ifStackTable can be defined along the lines of the following example, which complies with <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/> and <xref target="RFC6991" format="default" sectionFormat="of" derivedContent="RFC6991"/>.
      		In the example, "lower-layer-if" takes "ethernetCsmacd", but, in fact, "lower-layer-if" can be any other available link-data layer. See <xref target="sec7" format="default" sectionFormat="of" derivedContent="Appendix A"/> for more examples.
        </t>
        <figure anchor="xml_happy_1" align="left" suppress-title="false" pn="figure-1">
          <sourcecode name="" type="" markers="true" pn="section-3.1-4.1">

            &lt;interface&gt;
              &lt;name&gt;isis_int&lt;/name&gt;
              &lt;type&gt;ianaift:ipForward&lt;/type&gt;
            &lt;/interface&gt;

            &lt;interface&gt;
              &lt;name&gt;eth1&lt;/name&gt;
              &lt;type&gt;ianaift:ethernetCsmacd&lt;/type&gt;
            &lt;/interface&gt;

            &lt;interface&gt;
              &lt;name&gt;p2p&lt;/name&gt;
              &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
              &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
              &lt;lower-layer-if&gt;eth1&lt;/lower-layer-if&gt;
              &lt;enabled&gt;false&lt;/enabled&gt;
              &lt;admin-status&gt;down&lt;/admin-status&gt;
              &lt;oper-status&gt;down&lt;/oper-status&gt;
              &lt;statistics&gt;
                &lt;discontinuity-time&gt;
                  2021-04-01T03:00:00+00:00
                &lt;/discontinuity-time&gt;
                &lt;!-- counters now shown here --&gt;
              &lt;/statistics&gt;
            &lt;/interface&gt;

</sourcecode>
        </figure>
      </section>
      <section anchor="sec3_2" numbered="true" toc="include" removeInRFC="false" pn="section-3.2">
        <name slugifiedName="name-p2p-interface-statistics">P2P Interface Statistics</name>
        <t indent="0" pn="section-3.2-1">Because multiple IP interfaces can be bound to one physical port, 
      		 the statistics on the physical port <bcp14>SHOULD</bcp14> be a complete set that includes statistics of all upper-layer interfaces. 
      		 Therefore, each P2P interface collects and displays traffic that has been sent to it via 
      		 higher layers or received from it via lower layers.
        </t>
      </section>
      <section anchor="sec3_3" numbered="true" toc="include" removeInRFC="false" pn="section-3.3">
        <name slugifiedName="name-p2p-interface-administrativ">P2P Interface Administrative State</name>
        <t indent="0" pn="section-3.3-1">The P2P interface can be shut down independently of the underlying interface.
        </t>
        <t indent="0" pn="section-3.3-2">If the P2P interface is administratively up, 
      		 then the "oper-status" (defined in <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/>) of that interface <bcp14>SHALL</bcp14> fully reflect the state of the underlying interface; 
      		 if the P2P interface is administratively down, 
      		 then the "oper-status" of that interface <bcp14>SHALL</bcp14> be down. Examples can be found in <xref target="sec7" format="default" sectionFormat="of" derivedContent="Appendix A"/>.
        </t>
      </section>
    </section>
    <section numbered="true" toc="include" removeInRFC="false" pn="section-4">
      <name slugifiedName="name-security-considerations">Security Considerations</name>
      <t indent="0" pn="section-4-1">The writable attribute "admin-status" of the p2povervlan ifType is inherited from <xref target="RFC8343" format="default" sectionFormat="of" derivedContent="RFC8343"/>. 
      	 Other objects associated with the p2povervlan ifType are read-only. 
      	 With this in mind, the considerations discussed in <xref target="RFC8343" sectionFormat="of" section="7" format="default" derivedLink="https://rfc-editor.org/rfc/rfc8343#section-7" derivedContent="RFC8343"/> otherwise apply to the p2povervlan ifType.
      </t>
    </section>
    <section numbered="true" toc="include" removeInRFC="false" pn="section-5">
      <name slugifiedName="name-iana-considerations">IANA Considerations</name>
      <t indent="0" pn="section-5-1">In the "Interface Types (ifType)" registry, value 303 is assigned 
      to p2pOverLan <xref target="Assignment" format="default" sectionFormat="of" derivedContent="Assignment"/>. As this document explains how the p2pOverLan (303) ifType is to be used, IANA has amended the reference for p2pOverLan (303) to point to this document (instead of <xref target="RFC5309" format="default" sectionFormat="of" derivedContent="RFC5309"/>) and
made a similar amendment in the YANG iana-if-type module <xref target="IANA-ifTYPE" format="default" sectionFormat="of" derivedContent="IANA-ifTYPE"/> (originally specified in <xref target="RFC7224" format="default" sectionFormat="of" derivedContent="RFC7224"/>).
      </t>
    </section>
  </middle>
  <back>
    <references pn="section-6">
      <name slugifiedName="name-references">References</name>
      <references pn="section-6.1">
        <name slugifiedName="name-normative-references">Normative References</name>
        <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="RFC2863" target="https://www.rfc-editor.org/info/rfc2863" quoteTitle="true" derivedAnchor="RFC2863">
          <front>
            <title>The Interfaces Group MIB</title>
            <author fullname="K. McCloghrie" initials="K" surname="McCloghrie"/>
            <author fullname="F. Kastenholz" initials="F" surname="Kastenholz"/>
            <date month="June" year="2000"/>
            <abstract>
              <t indent="0">This memo discusses the 'interfaces' group of MIB-II, especially the experience gained from the definition of numerous media-specific MIB modules for use in conjunction with the 'interfaces' group for managing various sub-layers beneath the internetwork-layer.  It specifies clarifications to, and extensions of, the architectural issues within the MIB-II model of the 'interfaces' group. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2863"/>
          <seriesInfo name="DOI" value="10.17487/RFC2863"/>
        </reference>
        <reference anchor="RFC5309" target="https://www.rfc-editor.org/info/rfc5309" quoteTitle="true" derivedAnchor="RFC5309">
          <front>
            <title>Point-to-Point Operation over LAN in Link State Routing Protocols</title>
            <author fullname="N. Shen" initials="N" role="editor" surname="Shen"/>
            <author fullname="A. Zinin" initials="A" role="editor" surname="Zinin"/>
            <date month="October" year="2008"/>
            <abstract>
              <t indent="0">The two predominant circuit types used by link state routing protocols are point-to-point and broadcast.  It is important to identify the correct circuit type when forming adjacencies, flooding link state database packets, and representing the circuit topologically.  This document describes a simple mechanism to treat the broadcast network as a point-to-point connection from the standpoint of IP routing.  This memo provides information for the Internet community.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5309"/>
          <seriesInfo name="DOI" value="10.17487/RFC5309"/>
        </reference>
        <reference anchor="RFC7224" target="https://www.rfc-editor.org/info/rfc7224" quoteTitle="true" derivedAnchor="RFC7224">
          <front>
            <title>IANA Interface Type YANG Module</title>
            <author fullname="M. Bjorklund" initials="M" surname="Bjorklund"/>
            <date month="May" year="2014"/>
            <abstract>
              <t indent="0">This document defines the initial version of the iana-if-type YANG module.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7224"/>
          <seriesInfo name="DOI" value="10.17487/RFC7224"/>
        </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="RFC8343" target="https://www.rfc-editor.org/info/rfc8343" quoteTitle="true" derivedAnchor="RFC8343">
          <front>
            <title>A YANG Data Model for Interface Management</title>
            <author fullname="M. Bjorklund" initials="M" surname="Bjorklund"/>
            <date month="March" year="2018"/>
            <abstract>
              <t indent="0">This document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics).</t>
              <t indent="0">The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342.</t>
              <t indent="0">This document obsoletes RFC 7223.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="8343"/>
          <seriesInfo name="DOI" value="10.17487/RFC8343"/>
        </reference>
      </references>
      <references pn="section-6.2">
        <name slugifiedName="name-informative-references">Informative References</name>
        <reference anchor="Assignment" target="https://www.iana.org/assignments/smi-numbers" quoteTitle="true" derivedAnchor="Assignment">
          <front>
            <title>Interface Types (ifType)</title>
            <author>
              <organization showOnFrontPage="true">IANA</organization>
            </author>
          </front>
        </reference>
        <reference anchor="IANA-ifTYPE" target="https://www.iana.org/assignments/yang-parameters" quoteTitle="true" derivedAnchor="IANA-ifTYPE">
          <front>
            <title>YANG Module Names</title>
            <author>
              <organization showOnFrontPage="true">IANA</organization>
            </author>
          </front>
        </reference>
        <reference anchor="RFC6991" target="https://www.rfc-editor.org/info/rfc6991" quoteTitle="true" derivedAnchor="RFC6991">
          <front>
            <title>Common YANG Data Types</title>
            <author fullname="J. Schoenwaelder" initials="J" role="editor" surname="Schoenwaelder"/>
            <date month="July" year="2013"/>
            <abstract>
              <t indent="0">This document introduces a collection of common data types to be used with the YANG data modeling language.  This document obsoletes RFC 6021.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6991"/>
          <seriesInfo name="DOI" value="10.17487/RFC6991"/>
        </reference>
        <reference anchor="RFC8126" target="https://www.rfc-editor.org/info/rfc8126" quoteTitle="true" derivedAnchor="RFC8126">
          <front>
            <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
            <author fullname="M. Cotton" initials="M" surname="Cotton"/>
            <author fullname="B. Leiba" initials="B" surname="Leiba"/>
            <author fullname="T. Narten" initials="T" surname="Narten"/>
            <date month="June" year="2017"/>
            <abstract>
              <t indent="0">Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA).</t>
              <t indent="0">To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry.</t>
              <t indent="0">This is the third edition of this document; it obsoletes RFC 5226.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="26"/>
          <seriesInfo name="RFC" value="8126"/>
          <seriesInfo name="DOI" value="10.17487/RFC8126"/>
        </reference>
      </references>
    </references>
    <section anchor="sec7" numbered="true" toc="include" removeInRFC="false" pn="section-appendix.a">
      <name slugifiedName="name-examples">Examples</name>
      <t indent="0" pn="section-appendix.a-1">If the underlying interface is a VLAN sub-interface, the ifStackTable should be defined as:
      </t>
      <figure anchor="xml_happy_2" align="left" suppress-title="false" pn="figure-2">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-2.1">

          &lt;interface&gt;
            &lt;name&gt;isis_int&lt;/name&gt;
            &lt;type&gt;ianaift:ipForward&lt;/type&gt;
          &lt;/interface&gt;

          &lt;interface&gt;
            &lt;name&gt;eth1_valn1&lt;/name&gt;
            &lt;type&gt;ianaift:l2vlan&lt;/type&gt;
          &lt;/interface&gt;

          &lt;interface&gt;
            &lt;name&gt;p2p&lt;/name&gt;
            &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
            &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
            &lt;lower-layer-if&gt;eth1_valn1&lt;/lower-layer-if&gt;
            &lt;enabled&gt;false&lt;/enabled&gt;
            &lt;admin-status&gt;down&lt;/admin-status&gt;
            &lt;oper-status&gt;down&lt;/oper-status&gt;
            &lt;statistics&gt;
              &lt;discontinuity-time&gt;
                2021-04-01T03:00:00+00:00
              &lt;/discontinuity-time&gt;
              &lt;!-- counters now shown here --&gt;
            &lt;/statistics&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
      <t indent="0" pn="section-appendix.a-3">If the underlying interface is Link Aggregation Group (LAG), the ifStackTable should be defined as:
      </t>
      <figure anchor="xml_happy_3" align="left" suppress-title="false" pn="figure-3">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-4.1">

          &lt;interface&gt;
            &lt;name&gt;isis_int&lt;/name&gt;
            &lt;type&gt;ianaift:ipForward&lt;/type&gt;
          &lt;/interface&gt;

          &lt;interface&gt;
            &lt;name&gt;eth1_lag1&lt;/name&gt;
            &lt;type&gt;ianaift:ieee8023adLag&lt;/type&gt;
          &lt;/interface&gt;

          &lt;interface&gt;
            &lt;name&gt;p2p&lt;/name&gt;
            &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
            &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
            &lt;lower-layer-if&gt;eth1_lag1&lt;/lower-layer-if&gt;
            &lt;enabled&gt;false&lt;/enabled&gt;
            &lt;admin-status&gt;down&lt;/admin-status&gt;
            &lt;oper-status&gt;down&lt;/oper-status&gt;
            &lt;statistics&gt;
              &lt;discontinuity-time&gt;
                2021-04-01T03:00:00+00:00
              &lt;/discontinuity-time&gt;
              &lt;!-- counters now shown here --&gt;
            &lt;/statistics&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
      <t indent="0" pn="section-appendix.a-5">If the P2P interface and underlying interface are both administratively up and the underlying interface operational status is up:
      </t>
      <figure anchor="xml_happy_4" align="left" suppress-title="false" pn="figure-4">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-6.1">

          &lt;interface&gt;
             &lt;name&gt;p2p&lt;/name&gt;
             &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
             &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
             &lt;lower-layer-if&gt;eth1&lt;/lower-layer-if&gt;
             &lt;admin-status&gt;up&lt;/admin-status&gt;
             &lt;oper-status&gt;up&lt;/oper-status&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
      <t indent="0" pn="section-appendix.a-7">If the P2P interface and underlying interface are administratively up but the underlying interface operational status is down:
      </t>
      <figure anchor="xml_happy_5" align="left" suppress-title="false" pn="figure-5">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-8.1">

          &lt;interface&gt;
             &lt;name&gt;p2p&lt;/name&gt;
             &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
             &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
             &lt;lower-layer-if&gt;eth1&lt;/lower-layer-if&gt;
             &lt;admin-status&gt;up&lt;/admin-status&gt;
             &lt;oper-status&gt;down&lt;/oper-status&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
      <t indent="0" pn="section-appendix.a-9">If the P2P interface is administratively down:
      </t>
      <figure anchor="xml_happy_6" align="left" suppress-title="false" pn="figure-6">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-10.1">

          &lt;interface&gt;
             &lt;name&gt;p2p&lt;/name&gt;
             &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
             &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
             &lt;lower-layer-if&gt;eth1&lt;/lower-layer-if&gt;
             &lt;admin-status&gt;down&lt;/admin-status&gt;
             &lt;oper-status&gt;down&lt;/oper-status&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
      <t indent="0" pn="section-appendix.a-11">If the P2P interface is administratively up but the underlying interface is administratively down:
      </t>
      <figure anchor="xml_happy_7" align="left" suppress-title="false" pn="figure-7">
        <sourcecode name="" type="" markers="true" pn="section-appendix.a-12.1">

          &lt;interface&gt;
             &lt;name&gt;p2p&lt;/name&gt;
             &lt;type&gt;ianaift:p2pOverLan&lt;/type&gt;
             &lt;higher-layer-if&gt;isis_int&lt;/higher-layer-if&gt;
             &lt;lower-layer-if&gt;eth1&lt;/lower-layer-if&gt;
             &lt;admin-status&gt;up&lt;/admin-status&gt;
             &lt;oper-status&gt;down&lt;/oper-status&gt;
          &lt;/interface&gt;

</sourcecode>
      </figure>
    </section>
    <section anchor="sec8" numbered="false" toc="include" removeInRFC="false" pn="section-appendix.b">
      <name slugifiedName="name-acknowledgements">Acknowledgements</name>
      <t indent="0" pn="section-appendix.b-1">The authors would like to thank <contact fullname="Rob Wilton"/> for his reviews and valuable comments and suggestions.</t>
    </section>
    <section anchor="authors-addresses" numbered="false" removeInRFC="false" toc="include" pn="section-appendix.c">
      <name slugifiedName="name-authors-addresses">Authors' Addresses</name>
      <author initials="D." surname="Liu" fullname="Daiying Liu">
        <organization showOnFrontPage="true">Ericsson</organization>
        <address>
          <postal>
            <street>No.5 Lize East Street</street>
            <code>100102</code>
            <city>Beijing</city>
            <country>China</country>
          </postal>
          <email>harold.liu@ericsson.com</email>
        </address>
      </author>
      <author initials="J." surname="Halpern" fullname="Joel Halpern">
        <organization showOnFrontPage="true">Ericsson</organization>
        <address>
          <email>joel.halpern@ericsson.com</email>
        </address>
      </author>
      <author initials="C." surname="Zhang" fullname="Congjie Zhang">
        <organization showOnFrontPage="true">Ericsson</organization>
        <address>
          <email>congjie.zhang@ericsson.com</email>
        </address>
      </author>
    </section>
  </back>
</rfc>
