<?xml version='1.0' encoding='utf-8'?>
<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" category="std" docName="draft-ietf-bfd-large-packets-16" number="9764" consensus="true" ipr="trust200902" submissionType="IETF" xml:lang="en" tocInclude="true" tocDepth="4" updates="" obsoletes="" symRefs="true" sortRefs="true" prepTime="2025-04-04T10:31:51" indexInclude="true" scripts="Common,Latin">
  <link href="https://datatracker.ietf.org/doc/draft-ietf-bfd-large-packets-16" rel="prev"/>
  <link href="https://dx.doi.org/10.17487/rfc9764" rel="alternate"/>
  <link href="urn:issn:2070-1721" rel="alternate"/>
  <front>
    <title abbrev="BFD Encapsulated in Large Packets">Bidirectional Forwarding Detection (BFD) Encapsulated in Large Packets</title>
    <seriesInfo name="RFC" value="9764" stream="IETF"/>
    <author fullname="Jeffrey Haas" initials="J." surname="Haas">
      <organization showOnFrontPage="true">Juniper Networks, Inc.</organization>
      <address>
        <postal>
          <street>1133 Innovation Way</street>
          <city>Sunnyvale</city>
          <region>CA</region>
          <code>94089</code>
          <country>United States of America</country>
        </postal>
        <email>jhaas@juniper.net</email>
      </address>
    </author>
    <author fullname="Albert Fu" initials="A." surname="Fu">
      <organization showOnFrontPage="true">Bloomberg L.P.</organization>
      <address>
        <postal>
          <street>731 Lexington Avenue</street>
          <city>New York</city>
          <region>NY</region>
          <code>10022</code>
          <country>United States of America</country>
        </postal>
        <email>afu14@bloomberg.net</email>
      </address>
    </author>
    <date month="04" year="2025"/>
    <area>RTG</area>
    <workgroup>bfp</workgroup>
    <abstract pn="section-abstract">
      <t indent="0" pn="section-abstract-1">
	    The Bidirectional Forwarding Detection (BFD) protocol is commonly used to verify
	    connectivity between two systems.  BFD packets are typically very small.  It is
	    desirable in some circumstances to know not only that the path between two systems is
	    reachable, but also that it is capable of carrying a payload of a particular size.
	    This document specifies how to implement such a mechanism using BFD in Asynchronous
	    mode.
      </t>
      <t indent="0" pn="section-abstract-2">
	    YANG modules for managing this mechanism are also defined in this document.  These
	    YANG modules augment the existing BFD YANG modules defined in RFC 9314.
	    The YANG modules in this document conform to the Network Management Datastore
	    Architecture (NMDA) (RFC 8342).
      </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 is an Internet Standards Track document.
        </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).  Further
            information on Internet Standards is available in 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/rfc9764" 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) 2025 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" 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" keepWithNext="true" 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-bfd-encapsulated-in-large-p">BFD Encapsulated in Large Packets</xref></t>
          </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-implementation-and-deployme">Implementation and Deployment Considerations</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-implementations-that-do-not">Implementations That Do Not Support Large BFD Packets</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-selecting-mtu-size-to-be-de">Selecting MTU Size To Be Detected</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-detecting-mtu-mismatches">Detecting MTU Mismatches</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-detecting-mtu-changes">Detecting MTU Changes</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-equal-cost-multipath-ecmp-o">Equal-Cost Multipath (ECMP) or Other Load-Balancing Considerations</xref></t>
              </li>
              <li pn="section-toc.1-1.4.2.6">
                <t indent="0" pn="section-toc.1-1.4.2.6.1"><xref derivedContent="4.6" format="counter" sectionFormat="of" target="section-4.6"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-s-bfd">S-BFD</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-bfd-encapsulated-in-large-pa">BFD Encapsulated in Large Packets YANG Module</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.5.2">
              <li pn="section-toc.1-1.5.2.1">
                <t indent="0" pn="section-toc.1-1.5.2.1.1"><xref derivedContent="5.1" format="counter" sectionFormat="of" target="section-5.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-data-model-overview">Data Model Overview</xref></t>
              </li>
              <li pn="section-toc.1-1.5.2.2">
                <t indent="0" pn="section-toc.1-1.5.2.2.1"><xref derivedContent="5.2" format="counter" sectionFormat="of" target="section-5.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-yang-module">YANG Module</xref></t>
              </li>
            </ul>
          </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-security-considerations">Security Considerations</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-yang-security-consideration">YANG Security Considerations</xref></t>
              </li>
            </ul>
          </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-iana-considerations">IANA Considerations</xref></t>
            <ul bare="true" empty="true" indent="2" spacing="compact" pn="section-toc.1-1.7.2">
              <li pn="section-toc.1-1.7.2.1">
                <t indent="0" pn="section-toc.1-1.7.2.1.1"><xref derivedContent="7.1" format="counter" sectionFormat="of" target="section-7.1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-the-ietf-xml-registry">The "IETF XML" Registry</xref></t>
              </li>
              <li pn="section-toc.1-1.7.2.2">
                <t indent="0" pn="section-toc.1-1.7.2.2.1"><xref derivedContent="7.2" format="counter" sectionFormat="of" target="section-7.2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-the-yang-module-names-regis">The "YANG Module Names" Registry</xref></t>
              </li>
            </ul>
          </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-acknowledgments">Acknowledgments</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 anchor="intro" numbered="true" removeInRFC="false" toc="include" pn="section-1">
      <name slugifiedName="name-introduction">Introduction</name>
      <t indent="0" pn="section-1-1">
	    The Bidirectional Forwarding Detection (BFD) <xref target="RFC5880" format="default" sectionFormat="of" derivedContent="RFC5880"/> protocol is commonly
	    used to verify connectivity between two systems.  However, some applications may require
	    that the Path MTU <xref target="RFC1191" format="default" sectionFormat="of" derivedContent="RFC1191"/> between those two systems meets a certain
	    minimum criterion.  When the Path MTU decreases below the minimum threshold, those
	    applications may wish to consider the path unusable.
      </t>
      <t indent="0" pn="section-1-2">
	    BFD may be encapsulated in a number of transport protocols.  An example is
	    single-hop BFD <xref target="RFC5881" format="default" sectionFormat="of" derivedContent="RFC5881"/>.  In that case, the link MTU configuration is
	    typically enough to guarantee communication between the two systems for that size MTU.
	    BFD Echo mode (<xref target="RFC5880" sectionFormat="of" section="6.4" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5880#section-6.4" derivedContent="RFC5880"/>) is sufficient to permit
	    verification of the Path MTU of such directly connected systems.  Previous proposals 
	    (e.g., <xref target="I-D.haas-xiao-bfd-echo-path-mtu" format="default" sectionFormat="of" derivedContent="BFD-ECHO-PATH-MTU"/>)
	    have been made for testing Path MTU for such directly connected systems.
	    However, in the case of multihop BFD <xref target="RFC5883" format="default" sectionFormat="of" derivedContent="RFC5883"/>, this guarantee does not hold.
      </t>
      <t indent="0" pn="section-1-3">
	    The encapsulation of BFD in multihop sessions is a simple UDP packet.  The BFD elements
	    of procedure (<xref target="RFC5880" sectionFormat="of" section="6.8.6" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5880#section-6.8.6" derivedContent="RFC5880"/>) cover validating the BFD
	    payload.  However, the specification is silent on the length of the encapsulation that is
	    carrying the BFD PDU.  While it is most common that the transport protocol payload (i.e.,
	    UDP) length is the exact size of the BFD PDU, this is not required by the elements of
	    procedure.  This leads to the possibility that the transport protocol length may be
	    larger than the contained BFD PDU.
      </t>
    </section>
    <section numbered="true" removeInRFC="false" toc="include" 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 numbered="true" removeInRFC="false" toc="include" pn="section-3">
      <name slugifiedName="name-bfd-encapsulated-in-large-p">BFD Encapsulated in Large Packets</name>
      <t indent="0" pn="section-3-1">
	    Support for BFD between two systems is typically configured, even if the actual session
	    may be dynamically created by a client protocol.  A new BFD variable is defined in this
	    document:
      </t>
      <dl newline="true" indent="3" spacing="normal" pn="section-3-2">
        <dt pn="section-3-2.1">bfd.PaddedPduSize</dt>
        <dd pn="section-3-2.2">
            The BFD transport protocol payload size (in bytes) is increased to this value.  The
            contents of this additional payload <bcp14>MUST</bcp14> be zero.  The contents of this additional
            payload <bcp14>SHOULD NOT</bcp14> be validated by the receiver. 

The minimum size of this variable
            <bcp14>MUST NOT</bcp14> be smaller than 24 or 26 bytes, as permitted by the element of BFD procedure; see
            <xref target="RFC5880" sectionFormat="of" section="6.8.6" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5880#section-6.8.6" derivedContent="RFC5880"/>.
	    </dd>
      </dl>
      <t indent="0" pn="section-3-3">
	    The Don't Fragment bit (<xref target="RFC0791" sectionFormat="of" section="2.3" format="default" derivedLink="https://rfc-editor.org/rfc/rfc791#section-2.3" derivedContent="RFC0791"/>)
	    of the IP payload, when using IPv4 encapsulation, <bcp14>MUST</bcp14> be set.
      </t>
    </section>
    <section numbered="true" removeInRFC="false" toc="include" pn="section-4">
      <name slugifiedName="name-implementation-and-deployme">Implementation and Deployment Considerations</name>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.1">
        <name slugifiedName="name-implementations-that-do-not">Implementations That Do Not Support Large BFD Packets</name>
        <t indent="0" pn="section-4.1-1">
	      While this document proposes no change to the BFD protocol, implementations may not
	      permit arbitrarily padded transport PDUs to carry BFD packets.  While  
	      <xref target="RFC5880" sectionFormat="of" section="6" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5880#section-6" derivedContent="RFC5880"/> warns against excessive pedantry, implementations may not work
	      with this mechanism without additional support.
        </t>
        <t indent="0" pn="section-4.1-2">
	      <xref target="RFC5880" sectionFormat="of" section="6.8.6" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5880#section-6.8.6" derivedContent="RFC5880"/> discusses the procedures for receiving
	      BFD Control packets.  The length of the BFD Control packet is validated to be less
              than or equal to the payload of the encapsulating protocol. When a receiving
              implementation is incapable of processing large BFD packets, it could manifest in one
              of two possible ways:
        </t>
        <ul bare="false" empty="false" indent="3" spacing="normal" pn="section-4.1-3">
          <li pn="section-4.1-3.1">
	      A receiving BFD implementation is incapable of accepting large BFD packets.
	      This is identical to the packet being discarded.
	      </li>
          <li pn="section-4.1-3.2">
	      A receiving BFD implementation is capable of accepting large BFD packets,
	      but the Control packet is improperly rejected during validation procedures.
	      This is identical to the packet being discarded.
	      </li>
        </ul>
        <t indent="0" pn="section-4.1-4">
	      In each of these cases, the BFD state machine would behave as if it were not
	      receiving Control packets, and the receiving implementation would follow normal BFD
	      procedures regarding not having received Control packets.
        </t>
        <t indent="0" pn="section-4.1-5">
              If large BFD packets is enabled on a session that is already in the Up state
              and the remote BFD system does not (or cannot) support receiving the padded
              BFD control packets, the session will go Down.
        </t>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.2">
        <name slugifiedName="name-selecting-mtu-size-to-be-de">Selecting MTU Size To Be Detected</name>
        <t indent="0" pn="section-4.2-1">
	      Since the consideration is Path MTU, BFD sessions using this feature only need to use an appropriate value of 
	      bfd.PaddedPduSize to exercise the Path MTU for the desired application.
	      This may be significantly smaller than the system's link MTU, e.g., desired Path MTU is
	      1512 bytes, while the interface MTU that BFD with large packets is running on is 9000
	      bytes.
        </t>
        <t indent="0" pn="section-4.2-2">
	      In the case multiple BFD clients desire to test the same BFD endpoints using
	      different bfd.PaddedPduSize parameters, implementations <bcp14>SHOULD</bcp14> select the largest
	      bfd.PaddedPduSize parameter from the configured sessions.  This is similar to
	      how implementations of BFD select the most aggressive timing parameters for multiple
	      sessions to the same endpoint.  Failure to select the largest size will result in BFD
	      sessions going to the Up state and dependent applications not having their MTU
	      requirements satisfied.
        </t>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.3">
        <name slugifiedName="name-detecting-mtu-mismatches">Detecting MTU Mismatches</name>
        <t indent="0" pn="section-4.3-1">
	      The accepted MTU for an interface is impacted by packet encapsulation
	      considerations at a given layer, e.g., Layer 2, Layer 3, tunnel, etc.  A common
	      misconfiguration of interface parameters is inconsistent MTU.  In the presence
	      of inconsistent MTU, it is possible for applications to have unidirectional
	      connectivity.
        </t>
        <t indent="0" pn="section-4.3-2">
	      When it is necessary for an application using BFD with Large Packets to test
              the bidirectional Path MTU, it is necessary to configure the
              bfd.PaddedPduSize parameter on each side of the BFD session. For example, if
	      the desire is to verify a 1512-byte MTU in both directions on an Ethernet or
              point-to-point link, each side of the BFD session must have bfd.PaddedPduSize
	      set to 1512.  In the absence of such consistent configuration, BFD with 
	      Large Packets may correctly determine unidirectional connectivity at the
	      tested MTU, but bidirectional MTU may not be properly validated.
        </t>
        <t indent="0" pn="section-4.3-3">
	      It should be noted that some interfaces may intentionally have different MTUs.
	      Setting the bfd.PaddedPduSize appropriately for each side of the BFD session
	      supports such scenarios.
        </t>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.4">
        <name slugifiedName="name-detecting-mtu-changes">Detecting MTU Changes</name>
        <t indent="0" pn="section-4.4-1">
              Once BFD sessions using Large Packets has reached the Up state,
              connectivity at the tested MTU(s) for the session is being
              validated.  If the Path MTU tested by the BFD with Large Packets
              session falls below the tested MTU, the BFD session will go Down.
        </t>
        <t indent="0" pn="section-4.4-2">
              In the opposite circumstance (where the Path MTU increases), the
              BFD session will continue without being impacted.  BFD for Large
              Packets only ensures that the minimally acceptable MTU for the
              session can be used.
        </t>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.5">
        <name slugifiedName="name-equal-cost-multipath-ecmp-o">Equal-Cost Multipath (ECMP) or Other Load-Balancing Considerations</name>
        <t indent="0" pn="section-4.5-1">
	      Various mechanisms are utilized to increase throughput between two endpoints
	      at various network layers.  Such features include Link Aggregation Groups (LAGs)
	      or ECMP forwarding. Such mechanisms balance traffic across multiple physical
	      links while hiding the details of that balancing from the higher networking
	      layers.  The details of that balancing are highly implementation specific.
        </t>
        <t indent="0" pn="section-4.5-2">
	      In the presence of such load-balancing mechanisms, it is possible to have
	      member links that are not properly forwarding traffic.  In such circumstances,
	      this will result in dropped traffic when traffic is chosen to be load balanced
	      across those member links.
        </t>
        <t indent="0" pn="section-4.5-3">
	      Such load-balancing mechanisms may not permit all link members to be properly
	      tested by BFD.  This is because the BFD Control packets may be forwarded only
	      along links that are up.  BFD on LAG interfaces, <xref target="RFC7130" format="default" sectionFormat="of" derivedContent="RFC7130"/>, was developed
	      to help cover one such scenario.  However, for testing forwarding over
	      multiple hops, there is no such specified general-purpose BFD mechanism for
	      exercising all links in an ECMP.  This may result in a BFD session being in
	      the Up state while some traffic may be dropped or otherwise negatively
	      impacted along some component links.
        </t>
        <t indent="0" pn="section-4.5-4">
	      Some BFD implementations utilize their internal understanding of the component
	      links and their resultant forwarding to exercise BFD in such a way to better
	      test the ECMP members and to tie the BFD session state to the health of that
	      ECMP.  Due to implementation-specific load balancing, it is not possible
	      to standardize such additional mechanisms for BFD.
        </t>
        <t indent="0" pn="section-4.5-5">
	      Misconfiguration of some member MTUs may lead to load balancing that may have
	      an inconsistent Path MTU depending on how the traffic is balanced.  While the
	      intent of BFD with large packets is to verify Path MTU, it is subject to the
	      same considerations above.
        </t>
        <t indent="0" pn="section-4.5-6">
	      This section applies to most, if not all, BFD techniques.
        </t>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-4.6">
        <name slugifiedName="name-s-bfd">S-BFD</name>
        <t indent="0" pn="section-4.6-1">
	    This mechanism also can be applied to other forms of BFD, including 
	    Seamless BFD (S-BFD) <xref target="RFC7880" format="default" sectionFormat="of" derivedContent="RFC7880"/>.
        </t>
      </section>
    </section>
    <section anchor="yang-module" numbered="true" removeInRFC="false" toc="include" pn="section-5">
      <name slugifiedName="name-bfd-encapsulated-in-large-pa">BFD Encapsulated in Large Packets YANG Module</name>
      <section anchor="data-model-overview" numbered="true" removeInRFC="false" toc="include" pn="section-5.1">
        <name slugifiedName="name-data-model-overview">Data Model Overview</name>
        <t indent="0" pn="section-5.1-1">
                This YANG module augments the "ietf-bfd" module to add a flag
                'padding' to enable this feature. The feature statement
                'padding' needs to be enabled to indicate that BFD encapsulated
                in large packets is supported by the implementation.
        </t>
        <t indent="0" pn="section-5.1-2">
                Further, this YANG module augments the YANG modules for single-hop,
                multihop, LAG, and MPLS to add the "pdu-size"
                parameter to those session types to configure large BFD packets.
        </t>
        <t indent="0" pn="section-5.1-3">
                Finally, similar to the grouping "client-cfg-parms" defined in 
                <xref section="2.1" target="RFC9314" format="default" sectionFormat="of" derivedLink="https://rfc-editor.org/rfc/rfc9314#section-2.1" derivedContent="RFC9314"/>, this YANG module defines a grouping
                "bfd-large-common" that may be utilized by BFD clients using
                "client-cfg-params" to uniformly add support for the feature
                defined in this RFC.
        </t>
        <figure align="left" suppress-title="false" pn="figure-1">
          <sourcecode type="yangtree" markers="false" pn="section-5.1-4.1">
module: ietf-bfd-large

  augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
            /bfd-ip-sh:sessions/bfd-ip-sh:session:
    +--rw pdu-size?   padded-pdu-size {padding}?
  augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh
            /bfd-ip-mh:session-groups/bfd-ip-mh:session-group:
    +--rw pdu-size?   padded-pdu-size {padding}?
  augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
            /bfd-lag:sessions/bfd-lag:session:
    +--rw pdu-size?   padded-pdu-size {padding}?
  augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls
            /bfd-mpls:session-groups/bfd-mpls:session-group:
    +--rw pdu-size?   padded-pdu-size {padding}?
</sourcecode>
        </figure>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-5.2">
        <name slugifiedName="name-yang-module">YANG Module</name>
        <t indent="0" pn="section-5.2-1">
                This YANG module imports 
                <xref target="RFC8349" format="default" sectionFormat="of" derivedContent="RFC8349">"A YANG Data Model for Routing Management (NMDA Version)"</xref>
                and 
                <xref target="RFC9314" format="default" sectionFormat="of" derivedContent="RFC9314">"YANG Data Model for Bidirectional Forwarding Detection (BFD)"</xref>.
        </t>
        <figure align="left" suppress-title="false" pn="figure-2">
          <sourcecode type="yang" markers="true" name="ietf-bfd-large@2025-04-04.yang" pn="section-5.2-2.1">
module ietf-bfd-large {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-large";
  prefix bfdl;

  import ietf-routing {
    prefix rt;
    reference
      "RFC 8349: A YANG Data Model for Routing Management
       (NMDA version)";
  }

  import ietf-bfd {
    prefix bfd;
    reference
      "RFC 9314: YANG Data Model for Bidirectional
       Forwarding Detection.";
  }

  import ietf-bfd-ip-sh {
    prefix bfd-ip-sh;
    reference
      "RFC 9314: YANG Data Model for Bidirectional
       Forwarding Detection.";
  }

  import ietf-bfd-ip-mh {
    prefix bfd-ip-mh;
    reference
      "RFC 9314: YANG Data Model for Bidirectional
       Forwarding Detection.";
  }

  import ietf-bfd-lag {
    prefix bfd-lag;
    reference
      "RFC 9314: YANG Data Model for Bidirectional
       Forwarding Detection.";
  }

  import ietf-bfd-mpls {
    prefix bfd-mpls;
    reference
      "RFC 9314: YANG Data Model for Bidirectional
       Forwarding Detection.";
  }

  organization
    "IETF BFD Working Group";

  contact
    "WG Web:   &lt;https://datatracker.ietf.org/wg/bfd&gt;
     WG List:  &lt;rtg-bfd@ietf.org&gt;

     Authors: Jeffrey Haas (jhaas@juniper.net)
              Albert Fu (afu14@bloomberg.net).";

  description
    "This YANG module augments the base BFD YANG module to add
     attributes related to support for BFD Encapsulated in Large
     Packets.  In particular, it adds a per-session parameter for the
     BFD Padded PDU Size.

     Copyright (c) 2025 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject to
     the license terms contained in, the Revised BSD License set
     forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9764
     (https://www.rfc-editor.org/info/rfc9764); see the RFC itself
     for full legal notices.

     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
     'MAY', and 'OPTIONAL' in this document are to be interpreted as
     described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.";

  revision 2025-04-04 {
    description
      "Initial Version.";
    reference
      "RFC 9764, Bidirectional Forwarding Detection (BFD)
       Encapsulated in Large Packets.";
  }

  feature padding {
    description
      "If supported, the feature allows for BFD sessions to be
       configured with padded PDUs in support of BFD Encapsulated in
       Large Packets.";
  }

  typedef padded-pdu-size {
    type uint16 {
      range "24..65535";
    }
    units "bytes";
    description
      "The size of the padded and encapsulated BFD control packets
       to be transmitted at Layer 3.  The BFD minimum control packet
       size is 24 or 26 octets; see Section 6.8.6 of RFC 5880.

       If the configured padded PDU size is smaller than the minimum
       sized packet of a given BFD session, then the minimum sized
       packet for the session will be used.

       The maximum padded PDU size may be limited by the supported
       interface MTU of the system.";
    reference
      "RFC 9764, Bidirectional Forwarding Detection (BFD)
       Encapsulated in Large Packets.";
  }

  grouping bfd-large-common {
    description
      "Common configuration and operational state for BFD
       Encapsulated in Large Packets.";
    reference
      "RFC 9764, Bidirectional Forwarding Detection (BFD)
       Encapsulated in Large Packets.";
    leaf pdu-size {
      if-feature "padding";
      type padded-pdu-size;
      description
        "If set, this configures the padded PDU size for the
         Asynchronous mode BFD session. By default, no additional
         padding is added to such packets.";
    }
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/"
        + "bfd-ip-sh:sessions/bfd-ip-sh:session" {
    uses bfd-large-common;
    description
      "Augment the 'bfd' container to add attributes related to BFD
       Encapsulated in Large Packets.";
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/"
        + "bfd-ip-mh:session-groups/bfd-ip-mh:session-group" {
    uses bfd-large-common;
    description
      "Augment the 'bfd' container to add attributes related to BFD
       Encapsulated in Large Packets.";
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/"
        + "bfd-lag:sessions/bfd-lag:session" {
    uses bfd-large-common;
    description
      "Augment the 'bfd' container to add attributes related to BFD
       Encapsulated in Large Packets.";
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/"
        + "bfd-mpls:session-groups/bfd-mpls:session-group" {
    uses bfd-large-common;
    description
      "Augment the 'bfd' container to add attributes related to BFD
       Encapsulated in Large Packets.";
  }
}

</sourcecode>
        </figure>
      </section>
    </section>
    <section numbered="true" removeInRFC="false" toc="include" pn="section-6">
      <name slugifiedName="name-security-considerations">Security Considerations</name>
      <t indent="0" pn="section-6-1">
	    This document does not change the underlying security considerations of the BFD protocol
	    or its encapsulations.
      </t>
      <t indent="0" pn="section-6-2">
	    On-path attackers that can selectively drop BFD packets, including those with large
	    MTUs, can cause BFD sessions to go Down.
      </t>
      <t indent="0" pn="section-6-3">
            The contents of the padding payload are set to zero.  This avoids implementation issues
            where the local uninitialized data may be leaked.
      </t>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-6.1">
        <name slugifiedName="name-yang-security-consideration">YANG Security Considerations</name>
        <t indent="0" pn="section-6.1-1">
                This section is modeled after the template described in
                <xref target="I-D.ietf-netmod-rfc8407bis" sectionFormat="of" section="3.7" format="default" derivedLink="https://datatracker.ietf.org/doc/html/draft-ietf-netmod-rfc8407bis-22#section-3.7" derivedContent="YANG-GUIDELINES"/>.
        </t>
        <t indent="0" pn="section-6.1-2">
                The "ietf-bfd-large" YANG module defines a data model that is
                designed to be accessed via YANG-based management protocols, such as
                NETCONF <xref target="RFC6241" format="default" sectionFormat="of" derivedContent="RFC6241"/> and RESTCONF <xref target="RFC8040" format="default" sectionFormat="of" derivedContent="RFC8040"/>. These protocols have to
                use a secure transport layer (e.g., SSH <xref target="RFC4252" format="default" sectionFormat="of" derivedContent="RFC4252"/>, TLS <xref target="RFC8446" format="default" sectionFormat="of" derivedContent="RFC8446"/>, and
                QUIC <xref target="RFC9000" format="default" sectionFormat="of" derivedContent="RFC9000"/>) and have to use mutual authentication.
        </t>
        <t indent="0" pn="section-6.1-3">
                The Network Configuration Access Control Model (NACM) <xref target="RFC8341" format="default" sectionFormat="of" derivedContent="RFC8341"/>
                provides the means to restrict access for particular NETCONF or
                RESTCONF users to a preconfigured subset of all available NETCONF or
                RESTCONF protocol operations and content.
        </t>
        <t indent="0" pn="section-6.1-4">
                There is one data node defined in this YANG module that is
                writable/creatable/deletable (i.e., "config true", which is the
                default).  All writable data nodes are likely to be reasonably
                sensitive or vulnerable in some network environments.  Write
                operations (e.g., edit-config) and delete operations to these data
                nodes without proper protection or authentication can have a negative
                effect on network operations.  The data node
                has particular sensitivities/vulnerabilities:
        </t>
        <ul bare="false" empty="false" indent="3" spacing="normal" pn="section-6.1-5">
          <li pn="section-6.1-5.1">
                    'pdu-size' specifies the targeted size of BFD control packets
                    encapsulated according to this proposal.  Changing this value for a
                    session in the Up state may cause the session to go down, perhaps
                    intentionally, if the session cannot accommodate such BFD control
                    packets.  Operators should be mindful that multiple BFD clients may
                    rely on the status of a given BFD session when changing this value.
                  </li>
        </ul>
        <t indent="0" pn="section-6.1-6">
                There are no particularly sensitive readable data nodes.
        </t>
        <t indent="0" pn="section-6.1-7">
                There are no particularly sensitive RPC or action operations.
        </t>
        <t indent="0" pn="section-6.1-8">
		  Modules that use the groupings that are defined in this document
		  should identify the corresponding security considerations.  For
		  example, reusing some of these groupings will expose privacy-related
		  information (e.g., 'node-example').  This module defines one such grouping,
		  "bfd-large-common", which contains the "pdu-size" data node whose security
		  considerations are documented above.
        </t>
      </section>
    </section>
    <section numbered="true" removeInRFC="false" toc="include" pn="section-7">
      <name slugifiedName="name-iana-considerations">IANA Considerations</name>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-7.1">
        <name slugifiedName="name-the-ietf-xml-registry">The "IETF XML" Registry</name>
        <t indent="0" pn="section-7.1-1">IANA has registered the following URI in the "ns" subregistry of the
                "IETF XML Registry" <xref target="RFC3688" format="default" sectionFormat="of" derivedContent="RFC3688"/>.</t>
        <dl spacing="compact" newline="false" indent="3" pn="section-7.1-2">
          <dt pn="section-7.1-2.1">URI:</dt>
          <dd pn="section-7.1-2.2">urn:ietf:params:xml:ns:yang:ietf-bfd-large</dd>
          <dt pn="section-7.1-2.3">Registrant Contact:</dt>
          <dd pn="section-7.1-2.4">The IESG</dd>
          <dt pn="section-7.1-2.5">XML:</dt>
          <dd pn="section-7.1-2.6">N/A; the requested URI is an XML namespace.</dd>
        </dl>
      </section>
      <section numbered="true" removeInRFC="false" toc="include" pn="section-7.2">
        <name slugifiedName="name-the-yang-module-names-regis">The "YANG Module Names" Registry</name>
        <t indent="0" pn="section-7.2-1">IANA has registered the following YANG module in the "YANG Module Names"
                registry <xref target="RFC6020" format="default" sectionFormat="of" derivedContent="RFC6020"/>.</t>
        <dl spacing="compact" newline="false" indent="3" pn="section-7.2-2">
          <dt pn="section-7.2-2.1">Name:</dt>
          <dd pn="section-7.2-2.2">ietf-bfd-large</dd>
          <dt pn="section-7.2-2.3">Maintained by IANA:</dt>
          <dd pn="section-7.2-2.4">N</dd>
          <dt pn="section-7.2-2.5">Namespace:</dt>
          <dd pn="section-7.2-2.6">urn:ietf:params:xml:ns:yang:ietf-bfd-large</dd>
          <dt pn="section-7.2-2.7">Prefix:</dt>
          <dd pn="section-7.2-2.8">bfdl</dd>
          <dt pn="section-7.2-2.9">Reference:</dt>
          <dd pn="section-7.2-2.10">RFC 9764</dd>
        </dl>
      </section>
    </section>
  </middle>
  <back>
    <displayreference target="I-D.haas-xiao-bfd-echo-path-mtu" to="BFD-ECHO-PATH-MTU"/>
    <displayreference target="I-D.ietf-netmod-rfc8407bis" to="YANG-GUIDELINES"/>
    <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="RFC0791" target="https://www.rfc-editor.org/info/rfc791" quoteTitle="true" derivedAnchor="RFC0791">
          <front>
            <title>Internet Protocol</title>
            <author fullname="J. Postel" initials="J." surname="Postel"/>
            <date month="September" year="1981"/>
          </front>
          <seriesInfo name="STD" value="5"/>
          <seriesInfo name="RFC" value="791"/>
          <seriesInfo name="DOI" value="10.17487/RFC0791"/>
        </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="RFC3688" target="https://www.rfc-editor.org/info/rfc3688" quoteTitle="true" derivedAnchor="RFC3688">
          <front>
            <title>The IETF XML Registry</title>
            <author fullname="M. Mealling" initials="M." surname="Mealling"/>
            <date month="January" year="2004"/>
            <abstract>
              <t indent="0">This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="81"/>
          <seriesInfo name="RFC" value="3688"/>
          <seriesInfo name="DOI" value="10.17487/RFC3688"/>
        </reference>
        <reference anchor="RFC5880" target="https://www.rfc-editor.org/info/rfc5880" quoteTitle="true" derivedAnchor="RFC5880">
          <front>
            <title>Bidirectional Forwarding Detection (BFD)</title>
            <author fullname="D. Katz" initials="D." surname="Katz"/>
            <author fullname="D. Ward" initials="D." surname="Ward"/>
            <date month="June" year="2010"/>
            <abstract>
              <t indent="0">This document describes a protocol intended to detect faults in the bidirectional path between two forwarding engines, including interfaces, data link(s), and to the extent possible the forwarding engines themselves, with potentially very low latency. It operates independently of media, data protocols, and routing protocols. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5880"/>
          <seriesInfo name="DOI" value="10.17487/RFC5880"/>
        </reference>
        <reference anchor="RFC5881" target="https://www.rfc-editor.org/info/rfc5881" quoteTitle="true" derivedAnchor="RFC5881">
          <front>
            <title>Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6 (Single Hop)</title>
            <author fullname="D. Katz" initials="D." surname="Katz"/>
            <author fullname="D. Ward" initials="D." surname="Ward"/>
            <date month="June" year="2010"/>
            <abstract>
              <t indent="0">This document describes the use of the Bidirectional Forwarding Detection (BFD) protocol over IPv4 and IPv6 for single IP hops. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5881"/>
          <seriesInfo name="DOI" value="10.17487/RFC5881"/>
        </reference>
        <reference anchor="RFC5883" target="https://www.rfc-editor.org/info/rfc5883" quoteTitle="true" derivedAnchor="RFC5883">
          <front>
            <title>Bidirectional Forwarding Detection (BFD) for Multihop Paths</title>
            <author fullname="D. Katz" initials="D." surname="Katz"/>
            <author fullname="D. Ward" initials="D." surname="Ward"/>
            <date month="June" year="2010"/>
            <abstract>
              <t indent="0">This document describes the use of the Bidirectional Forwarding Detection (BFD) protocol over multihop paths, including unidirectional links. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5883"/>
          <seriesInfo name="DOI" value="10.17487/RFC5883"/>
        </reference>
        <reference anchor="RFC6020" target="https://www.rfc-editor.org/info/rfc6020" quoteTitle="true" derivedAnchor="RFC6020">
          <front>
            <title>YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)</title>
            <author fullname="M. Bjorklund" initials="M." role="editor" surname="Bjorklund"/>
            <date month="October" year="2010"/>
            <abstract>
              <t indent="0">YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6020"/>
          <seriesInfo name="DOI" value="10.17487/RFC6020"/>
        </reference>
        <reference anchor="RFC7130" target="https://www.rfc-editor.org/info/rfc7130" quoteTitle="true" derivedAnchor="RFC7130">
          <front>
            <title>Bidirectional Forwarding Detection (BFD) on Link Aggregation Group (LAG) Interfaces</title>
            <author fullname="M. Bhatia" initials="M." role="editor" surname="Bhatia"/>
            <author fullname="M. Chen" initials="M." role="editor" surname="Chen"/>
            <author fullname="S. Boutros" initials="S." role="editor" surname="Boutros"/>
            <author fullname="M. Binderberger" initials="M." role="editor" surname="Binderberger"/>
            <author fullname="J. Haas" initials="J." role="editor" surname="Haas"/>
            <date month="February" year="2014"/>
            <abstract>
              <t indent="0">This document defines a mechanism to run Bidirectional Forwarding Detection (BFD) on Link Aggregation Group (LAG) interfaces. It does so by running an independent Asynchronous mode BFD session on every LAG member link.</t>
              <t indent="0">This mechanism allows the verification of member link continuity, either in combination with, or in absence of, Link Aggregation Control Protocol (LACP). It provides a shorter detection time than what LACP offers. The continuity check can also cover elements of Layer 3 (L3) bidirectional forwarding.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7130"/>
          <seriesInfo name="DOI" value="10.17487/RFC7130"/>
        </reference>
        <reference anchor="RFC7880" target="https://www.rfc-editor.org/info/rfc7880" quoteTitle="true" derivedAnchor="RFC7880">
          <front>
            <title>Seamless Bidirectional Forwarding Detection (S-BFD)</title>
            <author fullname="C. Pignataro" initials="C." surname="Pignataro"/>
            <author fullname="D. Ward" initials="D." surname="Ward"/>
            <author fullname="N. Akiya" initials="N." surname="Akiya"/>
            <author fullname="M. Bhatia" initials="M." surname="Bhatia"/>
            <author fullname="S. Pallagatti" initials="S." surname="Pallagatti"/>
            <date month="July" year="2016"/>
            <abstract>
              <t indent="0">This document defines Seamless Bidirectional Forwarding Detection (S-BFD), a simplified mechanism for using BFD with a large proportion of negotiation aspects eliminated, thus providing benefits such as quick provisioning, as well as improved control and flexibility for network nodes initiating path monitoring.</t>
              <t indent="0">This document updates RFC 5880.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="7880"/>
          <seriesInfo name="DOI" value="10.17487/RFC7880"/>
        </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="RFC8341" target="https://www.rfc-editor.org/info/rfc8341" quoteTitle="true" derivedAnchor="RFC8341">
          <front>
            <title>Network Configuration Access Control Model</title>
            <author fullname="A. Bierman" initials="A." surname="Bierman"/>
            <author fullname="M. Bjorklund" initials="M." surname="Bjorklund"/>
            <date month="March" year="2018"/>
            <abstract>
              <t indent="0">The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model.</t>
              <t indent="0">This document obsoletes RFC 6536.</t>
            </abstract>
          </front>
          <seriesInfo name="STD" value="91"/>
          <seriesInfo name="RFC" value="8341"/>
          <seriesInfo name="DOI" value="10.17487/RFC8341"/>
        </reference>
        <reference anchor="RFC8349" target="https://www.rfc-editor.org/info/rfc8349" quoteTitle="true" derivedAnchor="RFC8349">
          <front>
            <title>A YANG Data Model for Routing Management (NMDA Version)</title>
            <author fullname="L. Lhotka" initials="L." surname="Lhotka"/>
            <author fullname="A. Lindem" initials="A." surname="Lindem"/>
            <author fullname="Y. Qu" initials="Y." surname="Qu"/>
            <date month="March" year="2018"/>
            <abstract>
              <t indent="0">This document specifies three YANG modules and one submodule. Together, they form the core routing data model that serves as a framework for configuring and managing a routing subsystem. It is expected that these modules will be augmented by additional YANG modules defining data models for control-plane protocols, route filters, and other functions. The core routing data model provides common building blocks for such extensions -- routes, Routing Information Bases (RIBs), and control-plane protocols.</t>
              <t indent="0">The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA). This document obsoletes RFC 8022.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="8349"/>
          <seriesInfo name="DOI" value="10.17487/RFC8349"/>
        </reference>
        <reference anchor="RFC9314" target="https://www.rfc-editor.org/info/rfc9314" quoteTitle="true" derivedAnchor="RFC9314">
          <front>
            <title>YANG Data Model for Bidirectional Forwarding Detection (BFD)</title>
            <author fullname="M. Jethanandani" initials="M." role="editor" surname="Jethanandani"/>
            <author fullname="R. Rahman" initials="R." role="editor" surname="Rahman"/>
            <author fullname="L. Zheng" initials="L." role="editor" surname="Zheng"/>
            <author fullname="S. Pallagatti" initials="S." surname="Pallagatti"/>
            <author fullname="G. Mirsky" initials="G." surname="Mirsky"/>
            <date month="September" year="2022"/>
            <abstract>
              <t indent="0">This document defines a YANG data model that can be used to configure and manage Bidirectional Forwarding Detection (BFD).</t>
              <t indent="0">The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) (RFC 8342). This document updates "YANG Data Model for Bidirectional Forwarding Detection (BFD)" (RFC 9127).</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="9314"/>
          <seriesInfo name="DOI" value="10.17487/RFC9314"/>
        </reference>
      </references>
      <references pn="section-8.2">
        <name slugifiedName="name-informative-references">Informative References</name>
        <reference anchor="I-D.haas-xiao-bfd-echo-path-mtu" target="https://datatracker.ietf.org/doc/html/draft-haas-xiao-bfd-echo-path-mtu-01" quoteTitle="true" derivedAnchor="BFD-ECHO-PATH-MTU">
          <front>
            <title>Application of the BFD Echo function for Path MTU Verification or Detection</title>
            <author initials="X." surname="Min" fullname="Xiao Min" role="editor">
              <organization showOnFrontPage="true">ZTE Corporation</organization>
            </author>
            <author initials="J." surname="Haas" fullname="Jeffrey Haas" role="editor">
              <organization showOnFrontPage="true">Juniper Networks</organization>
            </author>
            <date month="July" day="11" year="2011"/>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-haas-xiao-bfd-echo-path-mtu-01"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
        <reference anchor="RFC1191" target="https://www.rfc-editor.org/info/rfc1191" quoteTitle="true" derivedAnchor="RFC1191">
          <front>
            <title>Path MTU discovery</title>
            <author fullname="J. Mogul" initials="J." surname="Mogul"/>
            <author fullname="S. Deering" initials="S." surname="Deering"/>
            <date month="November" year="1990"/>
            <abstract>
              <t indent="0">This memo describes a technique for dynamically discovering the maximum transmission unit (MTU) of an arbitrary internet path. It specifies a small change to the way routers generate one type of ICMP message. For a path that passes through a router that has not been so changed, this technique might not discover the correct Path MTU, but it will always choose a Path MTU as accurate as, and in many cases more accurate than, the Path MTU that would be chosen by current practice. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="1191"/>
          <seriesInfo name="DOI" value="10.17487/RFC1191"/>
        </reference>
        <reference anchor="RFC4252" target="https://www.rfc-editor.org/info/rfc4252" quoteTitle="true" derivedAnchor="RFC4252">
          <front>
            <title>The Secure Shell (SSH) Authentication Protocol</title>
            <author fullname="T. Ylonen" initials="T." surname="Ylonen"/>
            <author fullname="C. Lonvick" initials="C." role="editor" surname="Lonvick"/>
            <date month="January" year="2006"/>
            <abstract>
              <t indent="0">The Secure Shell Protocol (SSH) is a protocol for secure remote login and other secure network services over an insecure network. This document describes the SSH authentication protocol framework and public key, password, and host-based client authentication methods. Additional authentication methods are described in separate documents. The SSH authentication protocol runs on top of the SSH transport layer protocol and provides a single authenticated tunnel for the SSH connection protocol. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="4252"/>
          <seriesInfo name="DOI" value="10.17487/RFC4252"/>
        </reference>
        <reference anchor="RFC6241" target="https://www.rfc-editor.org/info/rfc6241" quoteTitle="true" derivedAnchor="RFC6241">
          <front>
            <title>Network Configuration Protocol (NETCONF)</title>
            <author fullname="R. Enns" initials="R." role="editor" surname="Enns"/>
            <author fullname="M. Bjorklund" initials="M." role="editor" surname="Bjorklund"/>
            <author fullname="J. Schoenwaelder" initials="J." role="editor" surname="Schoenwaelder"/>
            <author fullname="A. Bierman" initials="A." role="editor" surname="Bierman"/>
            <date month="June" year="2011"/>
            <abstract>
              <t indent="0">The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="6241"/>
          <seriesInfo name="DOI" value="10.17487/RFC6241"/>
        </reference>
        <reference anchor="RFC8040" target="https://www.rfc-editor.org/info/rfc8040" quoteTitle="true" derivedAnchor="RFC8040">
          <front>
            <title>RESTCONF Protocol</title>
            <author fullname="A. Bierman" initials="A." surname="Bierman"/>
            <author fullname="M. Bjorklund" initials="M." surname="Bjorklund"/>
            <author fullname="K. Watsen" initials="K." surname="Watsen"/>
            <date month="January" year="2017"/>
            <abstract>
              <t indent="0">This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF).</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="8040"/>
          <seriesInfo name="DOI" value="10.17487/RFC8040"/>
        </reference>
        <reference anchor="RFC8446" target="https://www.rfc-editor.org/info/rfc8446" quoteTitle="true" derivedAnchor="RFC8446">
          <front>
            <title>The Transport Layer Security (TLS) Protocol Version 1.3</title>
            <author fullname="E. Rescorla" initials="E." surname="Rescorla"/>
            <date month="August" year="2018"/>
            <abstract>
              <t indent="0">This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.</t>
              <t indent="0">This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="8446"/>
          <seriesInfo name="DOI" value="10.17487/RFC8446"/>
        </reference>
        <reference anchor="RFC9000" target="https://www.rfc-editor.org/info/rfc9000" quoteTitle="true" derivedAnchor="RFC9000">
          <front>
            <title>QUIC: A UDP-Based Multiplexed and Secure Transport</title>
            <author fullname="J. Iyengar" initials="J." role="editor" surname="Iyengar"/>
            <author fullname="M. Thomson" initials="M." role="editor" surname="Thomson"/>
            <date month="May" year="2021"/>
            <abstract>
              <t indent="0">This document defines the core of the QUIC transport protocol. QUIC provides applications with flow-controlled streams for structured communication, low-latency connection establishment, and network path migration. QUIC includes security measures that ensure confidentiality, integrity, and availability in a range of deployment circumstances. Accompanying documents describe the integration of TLS for key negotiation, loss detection, and an exemplary congestion control algorithm.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="9000"/>
          <seriesInfo name="DOI" value="10.17487/RFC9000"/>
        </reference>
        <reference anchor="I-D.ietf-netmod-rfc8407bis" target="https://datatracker.ietf.org/doc/html/draft-ietf-netmod-rfc8407bis-22" quoteTitle="true" derivedAnchor="YANG-GUIDELINES">
          <front>
            <title>Guidelines for Authors and Reviewers of Documents Containing YANG Data Models</title>
            <author initials="A." surname="Bierman" fullname="Andy Bierman">
              <organization showOnFrontPage="true">YumaWorks</organization>
            </author>
            <author initials="M." surname="Boucadair" fullname="Mohamed Boucadair" role="editor">
              <organization showOnFrontPage="true">Orange</organization>
            </author>
            <author initials="Q." surname="Wu" fullname="Qin Wu">
              <organization showOnFrontPage="true">Huawei</organization>
            </author>
            <date month="January" day="14" year="2025"/>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-ietf-netmod-rfc8407bis-22"/>
          <refcontent>Work in Progress</refcontent>
        </reference>
      </references>
    </references>
    <section numbered="false" removeInRFC="false" toc="include" pn="section-appendix.a">
      <name slugifiedName="name-acknowledgments">Acknowledgments</name>
      <t indent="0" pn="section-appendix.a-1">
	    The authors would like to thank <contact fullname="Les      Ginsberg"/>, <contact fullname="Mahesh Jethanandani"/>, <contact fullname="Robert Raszuk"/>, and <contact fullname="Ketan      Talaulikar"/>, for their valuable feedback on this proposal.
      </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="Jeffrey Haas" initials="J." surname="Haas">
        <organization showOnFrontPage="true">Juniper Networks, Inc.</organization>
        <address>
          <postal>
            <street>1133 Innovation Way</street>
            <city>Sunnyvale</city>
            <region>CA</region>
            <code>94089</code>
            <country>United States of America</country>
          </postal>
          <email>jhaas@juniper.net</email>
        </address>
      </author>
      <author fullname="Albert Fu" initials="A." surname="Fu">
        <organization showOnFrontPage="true">Bloomberg L.P.</organization>
        <address>
          <postal>
            <street>731 Lexington Avenue</street>
            <city>New York</city>
            <region>NY</region>
            <code>10022</code>
            <country>United States of America</country>
          </postal>
          <email>afu14@bloomberg.net</email>
        </address>
      </author>
    </section>
  </back>
</rfc>
