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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="info" ipr="trust200902" docName="draft-ietf-bier-oam-requirements-21" number="9974" consensus="true" obsoletes="" updates="" submissionType="IETF" xml:lang="en" tocInclude="true" tocDepth="3" symRefs="true" sortRefs="true" version="3">
  <!-- xml2rfc v2v3 conversion 3.6.0 -->
  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

  <front>
    <title abbrev="OAM Requirements for BIER">Operations, Administration Administration, and Maintenance (OAM) Requirements for the Bit Index Explicit Replication (BIER) Layer</title>
    <seriesInfo name="RFC" value="9974"/>
    <author initials="G." surname="Mirsky" fullname="Greg Mirsky" role="editor">
      <organization>Ericsson</organization>
      <address>
	<email>gregimirsky@gmail.com</email>
      </address>
    </author>

    <author initials="N." surname="Kumar" fullname="Nagendra Kumar">
      <organization>Oracle</organization>
      <address>
	<email>nagendrakumar.nainar@gmail.com</email>
      </address>
    </author>

    <author initials="M." surname="Chen" fullname="Mach Chen">
      <organization>Huawei Technologies</organization>
      <address>
	<email>mach.chen@huawei.com</email>
      </address>
    </author>

    <author initials="S" surname="Pallagatti" fullname="Santosh Pallagatti" role="editor">
      <organization>VMware</organization>
      <address>
	<email>santosh.pallagatti@gmail.com</email>
      </address>
    </author>

    <date year="2025"/>

    <area>Routing</area>

    <workgroup>BIER  Working Group</workgroup>

    <keyword>Internet-Draft</keyword> month="May" year="2026"/>

    <area>RTG</area>
    <workgroup>bier</workgroup>

    <keyword>BIER</keyword>
    <keyword>OAM</keyword>

	<abstract>
	<t>
	   This document specifies a list of functional requirements for Operations, Administration, and Maintenance
	   mechanisms, protocols, and tools that support operations in the Bit Index Explicit Replication layer of a network.
	 </t>
	</abstract>
  </front>

<middle>
  <section anchor="intro" title="Introduction"> anchor="intro">
    <name>Introduction</name>
        <t>
   <xref target="RFC8279"/> specifies a Bit Index Explicit Replication (BIER)
   architecture and how it supports forwarding of multicast data packets.
       </t>
       <t>
   This document lists the Operations, Administration, and Maintenance (OAM) requirements for the BIER layer
  (Section 4.2 of
  (see <xref target="RFC8279"/>) target="RFC8279" section="4.2"/>) of the multicast domain.
   The list can further be used for gap analysis of available OAM tools to identify
   whether possible enhancements of existing or whether new OAM tools are required to
   support proactive and on-demand path monitoring and service validation.
          </t>

     <section title="Conventions used

     <section>
       <name>Conventions Used in this document"> This Document</name>
         <section anchor="term-sec" title="Terminology"> anchor="term-sec">
	   <name>Terminology</name>
<t>The reader is expected to be familiar with:</t>
<ul spacing="normal">
<li><xref target="RFC7799"/>, particularly definitions of Active, Passive, and Hybrid measurement methods and metrics.</li>
<li>The definitions and calculation of performance metrics, e.g., throughput, loss, delay, and delay variation metrics, are defined in <xref target="RFC6374"/>.</li>
<li>The definitions, applicability, and examples of the Continuity Check and Connectivity Verification mechanisms, components of the Fault Management OAM,
can be found in  <xref target="RFC5860"/>,<xref target="RFC5860"/>, <xref target="RFC6371"/>, and <xref target="RFC7276"/>.</li>
<li>A multicast domain is a network segment that defines the scope for the multicast traffic, allowing it to be exchanged only among systems within the domain <xref target="RFC8279"/>.</li>
<li>The term "BIER OAM" is used in this document interchangeably with "a set of OAM protocols, methods, and tools for the BIER layer".</li>
<li>Downstream - is the direction from the ingress toward the egress endpoints of a multicast distribution tree.</li>
<li>Egress endpoint is a router to which the packet needs to be sent <xref target="RFC8279"/>.</li>
<li>Ingress endpoint is a router that encapsulates a packet in a BIER header <xref target="RFC8279"/>.</li>
<li>
   A BIER OAM session is a communication established between Bit-Forwarding Routers (BFR) to perform OAM
   functions like fault detection, performance monitoring, and localization <xref target="RFC7276"/>.
   These sessions can be proactive (continuous, persistent configuration) or on-demand (manual, temporary diagnostics).
 </li>
      </ul>

         </section>

        <section title="Requirements Language">

        <section>
	  <name>Requirements Language</name>
        <t>
    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&nbsp;14 <xref target="RFC2119"/> <xref
    target="RFC8174"/> when, and only when, they appear in all capitals, as
    shown here.
        </t>

    <t>The requirements language is used in <xref target="req-list"/> and applies to implementations
    of BIER OAM conformant to the listed requirements.</t>
          </section>
         <section title="Acronyms">
            <t>BFD:       Bidirectional
         <section>
	   <name>Acronyms</name>
	   <dl spacing="normal" newline="false">
             <dt>BFD:</dt><dd>Bidirectional Forwarding Detection <xref target="RFC8562"/></t>
            <t>BFR:       Bit-Forwarding target="RFC8562"/></dd>
             <dt>BFR:</dt><dd>Bit-Forwarding Router <xref target="RFC8279"/></t>
            <t>BFER:    Bit-Forwarding target="RFC8279"/></dd>
             <dt>BFER:</dt><dd>Bit-Forwarding Egress Router <xref target="RFC8279"/></t>
            <t>BIER:     Bit target="RFC8279"/></dd>
             <dt>BIER:</dt><dd>Bit Index Explicit Replication <xref target="RFC8279"/></t>
            <t>OAM:      Operations, target="RFC8279"/></dd>
             <dt>OAM:</dt><dd>Operations, Administration, and Maintenance <xref target="RFC6291"/></t>
            <t>PMTUD:  Path target="RFC6291"/></dd>
             <dt>PMTUD:</dt><dd>Path Maximum Transmission Unit Discovery <xref target="RFC1191"/></t>
            <t>p2mp:      Point-to-Multipoint <xref target="RFC8562"/></t>
            <t>RDI:        Remote target="RFC1191"/></dd>
             <dt>P2MP:</dt><dd>Point-to-Multipoint <xref target="RFC8562"/></dd>
             <dt>RDI:</dt><dd>Remote Defect Indication <xref target="RFC6428"/></t>
            <t>STAMP:   Simple target="RFC6428"/></dd>
             <dt>STAMP:</dt><dd>Simple Two-way Active Measurement Protocol <xref target="RFC8762"/></t> target="RFC8762"/></dd>
	   </dl>
         </section>
      </section>
     </section>

  <section anchor="req-list" title="Requirements"> anchor="req-list">
    <name>Requirements</name>
  <t>
  This section lists the requirements for OAM of the BIER layer:
  </t>
  <ol type="1">
  <li>
  The
    <li>The listed requirements MUST <bcp14>MUST</bcp14> be supported with any
    routing underlay <xref target="RFC8279"/> over which the BIER layer can be realized.
  </li>
  <li>
  It MUST
    realized.</li>
    <li>It <bcp14>MUST</bcp14> be possible to initialize a BIER OAM session
    from any BFR of the given BIER domain.
  </li>
  <li>
  It MUST domain.</li>
    <li>It <bcp14>MUST</bcp14> be possible to initialize a BIER OAM session from a controller.
  </li>
  <li>
  BIER controller.</li>
    <li>BIER OAM MUST <bcp14>MUST</bcp14> support proactive OAM monitoring and measurement methods.
  </li>
    <li>
  BIER methods.</li>
    <li>BIER OAM MUST <bcp14>MUST</bcp14> support on-demand OAM monitoring and measurement methods.
  </li>
   <li>
  BIER methods.</li>
    <li>BIER OAM MUST <bcp14>MUST</bcp14> support active performance measurement methods <xref target="RFC7799"/>.
  </li>
   <li>
  BIER target="RFC7799"/>.</li>
    <li>BIER OAM MUST <bcp14>MUST</bcp14> support passive performance measurement methods <xref target="RFC7799"/>.
  </li> target="RFC7799"/>.</li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support the ability of any BFR in the
      given BIER domain to proactively monitor Bit-Forwarding Egress Router (BFER) availability proactively.
</li>
</ol>
<t>
This
      availability.</t>

      <t>This requirement provides helpful clarification to the combination of
      Requirements 2 and 4. The p2mp P2MP BFD with active tail support <xref
      target="RFC9780"/> is an example of a protocol that provides
      notifications about the loss of connectivity in a multicast distribution tree.
</t>
<ol start="9" type="1">
      tree.</t>
    </li>
    <li>
  BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support downstream path continuity check.
  </li>
  </ol>
  <t>
  Bidirectional checking.</t>
      <t>Bidirectional Forwarding Detection (BFD) <xref target="RFC8562"/> is
      an example of a protocol that monitors the continuity of a multicast
      distribution tree.
  </t>
  <ol type="1" start="10"> tree.</t>
    </li>
    <li>
  BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support downstream performance measurement.
  </li>
  </ol>
  <t>
    Simple measurement.</t>
      <t>Simple Two-way Active Measurement Protocol (STAMP) <xref
      target="RFC8762"/> is an example of a protocol that supports measurement
      of performance metrics, e.g., packet loss ratio, delay, and delay variation.
  </t>
  <ol start="11" type="1">
      variation.</t>
    </li>
    <li>
  In
      <t>In the downstream direction, a BIER OAM solution MUST <bcp14>MUST</bcp14>
      support transmission of OAM packets to traverse the same set of nodes
      and links and receive the same forwarding treatment (including QoS) as
      the monitored BIER flow.
    </li>
    </ol>
    <t> flow.</t>
<!-- [rfced] Note that we have expanded CoS as "Class-of-Service" upon first use.  Please let us know if this is incorrect.

Original:
    In some cases, e.g., when monitoring a composite data flow that
   includes several sub-flows characterized by different CoS marking, an
   operator may choose to monitor the continuity of the path at the
   highest CoS, not at every CoS value in the data flow.
-->

      <t>In some cases, e.g., when monitoring a composite data flow that
      includes several sub-flows characterized by different Class-of-Service (CoS) marking, an
      operator may choose to monitor the continuity of the path at the highest
      CoS, not at every CoS value in the data flow. In that case, BIER OAM
      packets traverse the same set of nodes and links as the composite data
      flow while receiving the same forwarding treatment as the highest CoS
      sub-flow. In this scenario, the state of path continuity for lower CoS
      sub-flows can be derived from the state of the highest CoS, as
      determined by the BIER OAM protocol performing continuity verification
      (e.g., BFD).
    </t>
    <ol start="12" type="1"> BFD).</t>
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support bidirectional OAM methods. In
      the downstream direction, these methods of monitoring or measurement MUST
      <bcp14>MUST</bcp14> conform to Requirement 11.  In the reverse direction
      (i.e., from the egress toward the ingress endpoint of the BIER OAM test
      session), BIER OAM packets MAY <bcp14>MAY</bcp14> deviate from traversing
      the same set of nodes and links, or receive a different forwarding
      treatment (including QoS) as the monitored BIER flow.
  </li>
  </ol> flow.</t>
      <t>Point-to-Multipoint (p2mp) (P2MP) BFD with active tail <xref target="RFC9780"/>)
      target="RFC9780"/> is an example of the bidirectional mechanism of
      continuity checking.
  </t>

<ol start="13" type="1"> checking.</t>
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support Path Maximum Transmission Unit discovery (PMTUD).
</li>
</ol>
<t>
The
      Discovery (PMTUD).</t>
      <t>The PMTUD using ICMP <xref target="RFC1191"/> is an example of the mechanism.
</t>
<ol start="14" type="1">
      mechanism.</t>
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support an RDI mechanism to notify the
      BFR, the source of the continuity checking by BFERs.
</li>
</ol>
<t>
The BFERs.</t>
      <t>The Diagnostic field in p2mp P2MP BFD with active tail support, as
      described in Section 5
of <xref section="5" target="RFC9780"/>, is an example of the
      RDI mechanism.
</t>
<ol start="15" type="1"> mechanism.</t>
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support downstream performance
      measurement method(s) that (together) calculate performance metrics,
      e.g., throughput, loss, delay, and delay variation metrics <xref target="RFC6374"/>.
</li>
</ol>
<t>
STAMP
      target="RFC6374"/>.</t>

      <t>STAMP (<xref target="RFC8762"/> and <xref target="RFC8972"/>) is an
      example of an active performance measurement method of performance
      metrics that may be applied in a BIER domain. The Alternate Marking Alternate-Marking
      Method, described in <xref target="RFC9341"/> and <xref
      target="RFC9342"/>, is an example of a hybrid measurement method (<xref target="RFC7799"/>) <xref
      target="RFC7799"/> that may be applied in a BIER domain.
</t>
<ol start="16" type="1"> domain.</t>
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support defect notification mechanism(s).
</li>
</ol>
      mechanism(s).</t>
      <t>Alarm Indication Signal <xref target="RFC6427"/> is an example of the
      defect notification mechanism.</t>
<ol start="17" type="1">
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support a way for any BFR in the given
      BIER domain to originate a fault management message addressed to any
      subset of BFRs within the domain.
</li>
</ol> domain.</t>
      <t><xref target="RFC6427"/> provides an example of a Fault Management
      messaging mechanism.</t>
<ol start="18" type="1">
    </li>
    <li>
BIER
      <t>BIER OAM MUST <bcp14>MUST</bcp14> support methods to enable the
      survivability of a BIER layer.
</li>
  </ol> layer.</t>
      <t>Protection switching and restoration are examples of survivability
      methods.</t>
    </li>
  </ol>

</section>

  <section anchor="iana-considerations" title="IANA Considerations"> anchor="iana-considerations">
    <name>IANA Considerations</name>

  <t>
This document does not propose any has no IANA consideration. This section may be removed. actions.
  </t>
  </section>

   <section anchor="security-considerations" title="Security Considerations"> anchor="security-considerations">
     <name>Security Considerations</name>
   <t>
   This document lists the OAM requirements for a BIER-enabled domain and
  it thus inherits the security considerations discussed in <xref target="RFC8279"/> and <xref target="RFC8296"/>.
  Another general security aspect results from using active OAM protocols (<xref target="RFC7799"/>) <xref target="RFC7799"/> in a multicast network.
  </t>
<!-- [rfced] What does the "echo request/reply principle" refer to?  Please consider whether a reference should be added for the reader.

Original:
   Some
   active OAM protocols are based on the echo request/reply principle of
   using those test packets.
-->
  <t>
  Active OAM protocols inject specially constructed test packets.
  Some active OAM protocols are based on the echo request/reply principle of using those test packets.
In the multicast network, test packets are replicated as data packets,
thus creating a possible amplification effect of multiple echo replies being
transmitted to the sender of the echo request. Thus, Therefore, the following security-related requirements are defined for BIER OAM:
  </t>

<ul spacing="normal">
<li>A BIER OAM solution MUST <bcp14>MUST</bcp14> protect the control plane by controlling the rate of echo request transmission.</li>
<li>A BIER OAM solution MUST <bcp14>MUST</bcp14> provide control of the number of BIER OAM messages sent to the control plane.</li>
</ul>
   </section>

      <section anchor="Acknowledgements" numbered="true" toc="default">
      <name>Acknowledgements</name>
      <t>The authors would like to thank the comments and suggestions
	from Gunter van de Velde that helped improve this document.</t>
    </section>

  </middle>

    <back>
    <references title="Normative References">

    <references>
     <name>References</name>
    <references>
     <name>Normative References</name>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7799.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7799.xml"/>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6374.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6374.xml"/>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8279.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8279.xml"/>
     <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8296.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8296.xml"/>
    </references>

    <references title="Informative References">

    <references>
      <name>Informative References</name>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8762.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8762.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8972.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8972.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9341.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9341.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9342.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9342.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6291.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6291.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7276.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7276.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8562.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8562.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9780.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9780.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.1191.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.1191.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6428.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6428.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5860.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5860.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6371.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6371.xml"/>
      <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6427.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6427.xml"/>
    </references>
    </references>

    <section anchor="Acknowledgements" numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t>The authors would like to thank <contact fullname="Gunter van de Velde"/> for the comments and suggestions that helped improve this
      document.</t>
    </section>

    <section anchor="contr-sec" numbered="false" toc="default">
        <name>Contributors' Addresses</name>
        <name>Contributors</name>
        <author initials="E." surname="Nordmark" fullname="Erik Nordmark">
	  <organization/>
	  <address>
	    <email>nordmark@acm.org</email>
	  </address>
	</author>

	<author initials="S." surname="Aldrin" fullname="Sam Aldrin">
	  <organization>Google</organization>
	  <address>
	    <email>aldrin.ietf@gmail.com</email>
	  </address>
	</author>

	<author initials="L." surname="Zheng" fullname="Lianshu Zheng">
	  <organization/>
	  <address>
	    <email>veronique_cheng@hotmail.com</email>
	  </address>
	</author>

	<author initials="N." surname="Akiya" fullname="Nobo Akiya">
	  <organization/>
	  <address>
	    <email>nobo.akiya.dev@gmail.com</email>
	  </address>
	</author>
        </section>

<!-- [rfced] Please review the "Inclusive Language" portion of the online
Style Guide <https://www.rfc-editor.org/styleguide/part2/#inclusive_language>
and let us know if any changes are needed.  Updates of this nature typically
result in more precise language, which is helpful for readers.

Note that our script did not flag any words in particular, but this should
still be reviewed as a best practice.
-->

 </back>
 </rfc>