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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std" docName="draft-ietf-ospf-sr-yang-50"
number="9903" ipr="trust200902" obsoletes="" updates="" submissionType="IETF" xml:lang="en" tocInclude="true"
symRefs="true" sortRefs="true" consensus="true" version="3">
<!-- xml2rfc v2v3 conversion 3.16.0 -->
<!-- category values: std, bcp, info, exp, and historic
     ipr values: full3667, noModification3667, noDerivatives3667
     you can add the attributes updates="NNNN" and obsoletes="NNNN"
     they will automatically be output with "(if approved)" -->

<!-- ***** FRONT MATTER ***** -->

<front>
  <!-- The abbreviated title is used in the page header - it is only necessary if the
       full title is longer than 39 characters -->
  <title abbrev="OSPF SR MPLS SR-MPLS YANG" >
    A YANG Data Model for OSPF Segment Routing over the MPLS Data Plane
  </title>
  <seriesInfo name="Internet-Draft" value="draft-ietf-ospf-sr-yang-50"/>
  <!-- add 'role="editor"' below for the editors if appropriate -->

  <!-- Another author who claims to be an editor --> name="RFC" value="9903"/>
  <author fullname="Yingzhen Qu" initials="Y" surname="Qu">
    <organization>Futurewei Technologies</organization>
    <address>
      <phone/>
      <email>yingzhen.ietf@gmail.com</email>
      <!-- uri and facsimile elements may also be added -->
    </address>
  </author>
  <author fullname="Acee Lindem" initials="A." surname="Lindem">
    <organization>LabN Consulting, L.L.C.</organization>
    <address>
      <postal>
        <street>301 Midenhall Way</street>
        <city>Cary, NC 27513</city>
        <city>Cary</city><region>NC</region><code>27513</code>
	<country>United States of America</country>
      </postal>
      <email>acee.ietf@gmail.com</email>
    </address>
  </author>
  <author fullname="Jeffrey Zhang" initials="J" surname="Zhang">
    <organization>Juniper Networks</organization>
    <address>
      <postal>
        <street>10 Technology Park Drive</street>
        <!-- Reorder these if your country does things differently -->
        <city>Westford</city>
        <region>MA</region>
        <code>01886</code>
        <country>USA</country>
        <country>United States of America</country>
      </postal>
      <phone/>
      <email>zzhang@juniper.net</email>
      <!-- uri and facsimile elements may also be added -->
    </address>
  </author>
  <author fullname="Ing-Wher Chen" initials="I." surname="Chen">
    <organization>The MITRE Corporation</organization>
    <address>
      <email>ingwherchen@mitre.org</email>
    </address>
  </author>
  <date/>
  <date month="November" year="2025"/>
  <area>RTG</area>
  <workgroup>lsr</workgroup>

<!-- If the month and year are both specified and are the current ones, xml2rfc will fill
       in the current day for you. If only the current year is specified, xml2rfc will fill [rfced] Please insert any keywords (beyond those that appear in
the current day and month for you. If the year is not the current one, it is
       necessary to specify at least a month (xml2rfc assumes day="1" if not specified title) for the
       purpose of calculating the expiry date).  With drafts it is normally sufficient to
       specify just the year. -->

  <!-- Meta-data Declarations -->

  <area>General</area>
  <workgroup>Internet</workgroup>
  <!-- WG name at the upperleft corner of the doc,
       IETF is fine for individual submissions.
       If this element is not present, the default is "Network Working Group",
       which is used by the RFC Editor as a nod to the history of the IETF. -->

  <!-- Keywords will be incorporated into HTML output
       files in a meta tag but they have no effect use on text or nroff
       output. If you submit your draft to the RFC Editor, the
       keywords will be used for the search engine. https://www.rfc-editor.org/search. -->

<keyword>example</keyword>

  <abstract>
    <t>
      This document defines a YANG data model that can be
      used to manage OSPF Extensions extensions for Segment Routing over the MPLS data plane.
    </t>
  </abstract>
</front>
<middle>
  <section numbered="true" toc="default">
    <name>Overview</name>
    <t>
      This document defines a YANG data model <xref target="RFC7950" format="default"/> that can be used
      to manage OSPFv2 extensions for Segment Routing <xref target="RFC8665" format="default"/>
      and OSPFv3 extensions for Segment Routing <xref target="RFC8666" format="default"/>
      over the MPLS data plane.
      The defined YANG data model is an augmentation to the OSPF YANG data
      model <xref target="RFC9129" format="default"/>.
    </t>
    <t>
      The YANG data model in this document conforms to the Network Management
      Datastore Architecture (NMDA) <xref target="RFC8342" format="default"/>.
    </t>
    <section numbered="true" toc="default">
      <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" format="default"/> target="RFC2119"/> <xref target="RFC8174" format="default"/> target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.
        </t>
    </section>
    <section numbered="true" toc="default">
      <name>Tree Diagrams</name>
      <t>This document uses the graphical representation of a data model as
      defined in <xref target="RFC8340" format="default"/>.</t>
    </section>
  </section>
  <section numbered="true" toc="default"> <name>OSPF Segment Routing over MPLS YANG Data Model Scope</name>
    <t>
      The YANG data model in this document consists of a single YANG module, ietf-ospf-sr-mpls. "ietf-ospf-sr-mpls".
      The ietf-ospf-sr-mpls "ietf-ospf-sr-mpls" YANG module includes OSPF Segment Routing Extensions extensions for the MPLS
      data plane for both OSPFv2 <xref target="RFC8665" format="default"/> and
      OSPFv3 <xref target="RFC8666" format="default"/>.
    </t>
    <t>
      The ietf-ospf-sr-mpls "ietf-ospf-sr-mpls" YANG module requires support for the base segment
      routing Segment
      Routing module <xref target="RFC9020" format="default"/>,
      which defines the global segment routing Segment Routing configuration independent
      of any specific routing protocol configuration, and support of the OSPF base
      model <xref target="RFC9129" format="default"/> format="default"/>, which defines the basic
      OSPF configuration and state.
    </t>
    <t>
      The ietf-ospf-sr-mpls "ietf-ospf-sr-mpls" module defines both the data nodes to configure OSPF
      segment routing
      Segment Routing MPLS extensions and the additions to the OSPF Link State Advertisements (LSAs) necessary
      to support SR-MPLS. Segment Routing over MPLS (SR-MPLS). The OSPF configuration includes:
    </t>
    <ul spacing="normal">
      <li>
<!-- [rfced] We note that there is no mention of an "sr-protocol grouping"
in RFC 9020, but it does use "'sr-control-plane' grouping". Should the
parenthetical text below be updated to match what appears in RFC 9020?

Original:
   *  OSPF instance level configuration imported from the ietf-segment-routing-mpls ietf-segment-
      routing-mpls YANG module including the mapping server bindings and
      the per-protocol Segment Routing Global Block (SRGB) (refer to the
      sr-protocol grouping [RFC9020]).

Perhaps:
   *  OSPF instance level configuration imported from the ietf-segment-
      routing-mpls YANG module including the mapping server bindings and
      the per-protocol Segment Routing Global Block (SRGB) (refer to the
      "sr-control-plane" grouping [RFC9020]).
-->

      <li>
        OSPF instance level configuration imported from the "ietf-segment-routing-mpls"
        YANG module, including the mapping server bindings and the per-protocol Segment Routing
        Global Block (SRGB) (refer to the "sr-protocol" grouping <xref target="RFC9020"/>).
      </li>
      <li>
        OSPF area level configuration configuration, which enables segment routing Segment Routing over MPLS on all interfaces
        as wall well as advertisement of segment routing Segment Routing over MPLS information in
        Link State Advertisements (LSAs).
      </li>
      <li>
        OSPF interface level configuration for adjacency SIDs Adjacency Segment Identifiers (Adj-SIDs) corresponding to specific
        neighbors on multi-access interfaces (OSPF interface type broadcast or Non-Broadcast
        Multi-Access (NBMA)). The adjacency-sid definitions are imported from tht ietf-segment-routing-mpls the "ietf-segment-routing-mpls"
        YANG module (refer to the igp-interface "igp-interface" grouping <xref target="RFC9020"/>).
      </li>
      <li>
        OSPF interface level configuration for Topology-Independent Topology Independent Loop-Free Alternative (TI-LFA) using
        the MPLS data plane. TI-LFA is described in <xref target="I-D.ietf-rtgwg-segment-routing-ti-lfa"/>. target="RFC9855"/>.
      </li>
    </ul>
    <t>
     The operational state (read-only) additions to specifc specific to OSPFv2 LSA include:
    </t>
    <ul>
      <li>

<!-- [rfced] We note that RFCs 8665 and 8666 use "Extended Prefix Range TLV"
rather than "extended range TLV". May we update the two list items below
to match the corresponding RFCs?

Original:
   *  OSPFv2 extended range TLV encodings <xref target="RFC8665"/> [RFC8665] in the OSPF
      Extended-Prefix Opaque LSA <xref target="RFC7684"/>.
      </li>
      <li> [RFC7684].
   ...
   *  OSPFv3 extended range TLV encodings [RFC8666] in the OSPFv3 E-
      Intra-Area-Prefix-LSA, E-Inter-Area-Prefix-LSA, E-AS-External-LSA,
      and E-Type-7-LSA [RFC8362].

Perhaps:
   *  OSPFv2 Extended Prefix Range TLV encodings [RFC8665] in the OSPF
      Extended-Prefix Opaque LSA [RFC7684].
   ...
   *  OSPFv3 Extended Prefix Range TLV encodings [RFC8666] in the OSPFv3 E-
      Intra-Area-Prefix-LSA, E-Inter-Area-Prefix-LSA, E-AS-External-LSA,
      and E-Type-7-LSA [RFC8362].
-->

<!--[rfced] FYI - We have removed the following items from their
corresponding lists in Section 2 as they were each listed twice.

Original:
   *  OSPFv2 Prefix SID Sub-TLV encodings <xref target="RFC8665"/> [RFC8665] included the OSPF
      Extended Prefix TLV which is advertised in the OSPF Extended
      Prefix Opaque LSA [RFC7684].
   ...
   *  OSPFv3 extended range TLV encodings [RFC8666] in the OSPFv3 E-
      Intra-Area-Prefix-LSA, E-Inter-Area-Prefix-LSA, E-AS-External-LSA,
      and E-Type-7-LSA [RFC8362].
   ...
   *  OSPFv3 Adj-SID Sub-TLV [RFC8666] in the OSPFv3 Router-Link TLV
      [RFC8362].
-->

    <ul>
      <li>
        OSPFv2 extended range TLV encodings <xref target="RFC8665"/> in the OSPF
        Extended Prefix Opaque LSA <xref target="RFC7684"/>.
      </li>
      <li>
        OSPFv2 Prefix SID Prefix-SID Sub-TLV encodings <xref target="RFC8665"/> included target="RFC8665"/>, including
        the OSPF Extended Prefix TLV TLV, which is advertised in the OSPF Extended Prefix Opaque LSA
        <xref target="RFC7684"/>.
      </li>
      <li>
        OSPFv2 SR-Algorithm, SID/Label Range TLVs, TLV, SR Local Block TLVs, TLV, and Segment Routing Mapping Server (SRMS)
        preference
        Preference TLV <xref target="RFC8665"/> advertised in the OSPFv2 Router Information Opaque LSA
        <xref target="RFC7770"/>.
      </li>
    </ul>
    <t>
      The operational state (read-only) additions to specifc specific to OSPFv3 LSA include:
    </t>
    <ul>
      <li>
        OSPFv3 extended range TLV encodings <xref target="RFC8666"/> in the OSPFv3
        E-Intra-Area-Prefix-LSA, E-Inter-Area-Prefix-LSA, E-AS-External-LSA, and E-Type-7-LSA
        <xref target="RFC8362"/>.
      </li>
      <li>
        OSPFv3 extended range TLV encodings <xref target="RFC8666"/>

<!--[rfced] We note that there is no mention of "Extended Prefix Range TLV"
in the OSPFv3
        E-Intra-Area-Prefix-LSA, E-Inter-Area-Prefix-LSA, E-AS-External-LSA, RFC 8362, but it is defined in RFC 8666 (note that "Intra-Area-Prefix TLV",
"Inter-Area-Prefix TLV", and E-Type-7-LSA
        <xref target="RFC8362"/>.
      </li>
      <li> "External-Prefix TLV" are defined in RFC 8362).
Please review and let us know if/how the text or citation should be updated for
correctness.

Original:
   *  OSPFv3 Prefix-SID Sub-TLV encodings <xref target="RFC8666"/> [RFC8666] in the OSPFv3
        Intra-Area Intra-
      Area Prefix TLV, Inter-Area Prefix TLV, External Prefix TLV, and
      OSPFv3 Extended Prefix Range TLV <xref target="RFC8362"/>.
      </li> [RFC8362].
-->

      <li>
        OSPFv3 Adj-SID Prefix-SID Sub-TLV encodings <xref target="RFC8666"/> in the OSPFv3 Router-Link
        Intra-Area-Prefix TLV, Inter-Area-Prefix TLV, External-Prefix TLV, and
        OSPFv3 Extended Prefix Range TLV <xref target="RFC8362"/>.
      </li>
      <li>
        OSPFv3 Adj-SID Sub-TLV <xref target="RFC8666"/> in the
        OSPFv3 Router-Link TLV <xref target="RFC8362"/>.
      </li>
      <li>
        OSPFv3 LAN Adj-SID Sub-TLV <xref target="RFC8666"/> in the
        OSPFv3 Router-Link TLV <xref target="RFC8362"/>.
      </li>
      <li>
        OSPFv3 SR-Algorithm, SID/Label Range TLVs, TLV, SR Local Block TLVs, TLV, and Segment Routing Mapping Server (SRMS)
        preference
        Preference TLV <xref target="RFC8666"/> advertised in the OSPFv3 Router Information LSA
        <xref target="RFC7770"/>.
      </li>
    </ul>
  </section>

<section numbered="true" toc="default">
  <name>OSPF Segment Routing over MPLS YANG Module</name>

<!-- [rfced] We note that [RFC2328] and [RFC5340] are not referenced in the
YANG module but are listed in the introductory text for the YANG module.
Additionally, [RFC8665], [RFC8666], [RFC9020], and [RFC9129] are referenced
in the YANG module but are not listed in the introductory text. May we update
the introductory text as follows? Note that, if yes, we will also remove the
references for [RFC2328] and [RFC5340] from the Normative References section.

Original:
   [RFC2328], [RFC4915], [RFC5340], [RFC6991], [RFC8102], [RFC8294],
   [RFC8349], [RFC9587], and [I-D.ietf-rtgwg-segment-routing-ti-lfa] are
   referenced in the YANG module.

Perhaps:
   [RFC4915], [RFC6991], [RFC8102], [RFC8294], [RFC8349], [RFC8665],
   [RFC8666], [RFC9020]. [RFC9129], [RFC9587], and [RFC9855] are
   referenced in the YANG module.
-->

  <t>
    <xref target="RFC2328"/>, <xref target="RFC4915"/>, <xref target="RFC5340"/>,  <xref target="RFC6991"/>,
    <xref target="RFC8102"/>, <xref target="RFC8294"/>,
    <xref target="RFC8349"/>, <xref target="RFC9587"/>, and
    <xref target="I-D.ietf-rtgwg-segment-routing-ti-lfa" format="default"/> target="RFC9855"/>
    are referenced in the YANG module.
  </t>

<!--[rfced] We are having some difficulty parsing this description text
in the YANG module, particularly with "interface" repeated. Please review
and let us know how it should be updated for clarity.

Original:
   This augments broadcast and non-broadcast multi-access
   interface segment routing interface configuration.

Perhaps:
   This augments broadcast and non-broadcast multi-access
   interface Segment Routing and interface configuration.
-->

<!--[rfced] We have updated this description text in the YANG module for
clarity. Please review and confirm that the intended meaning has not been
altered.

Original:
   A path providing node a disjoint path for SRLG
   links from the primary path will be selected over
   one that doesn't provide an SRLG disjoint path.

Current:
   A path providing a node with a disjoint path for SRLG
   links from the primary path will be selected over
   a path that doesn't provide an SRLG disjoint path.
-->

<!--[rfced] We note that Derek Yeung is listed as an author in the
YANG module but is not listed as an author of this document. Should
we remove his name from the YANG module and add it to the
Acknowledgements section?

Original:
        Author:   Derek Yeung
                  <mailto:derek@arrcus.com>
-->

  <figure>
    <artwork><![CDATA[
<CODE BEGINS> file "ietf-ospf-sr-mpls@2025-05-09.yang"
    <sourcecode name="ietf-ospf-sr-mpls@2025-11-21.yang" type="yang" markers="true"><![CDATA[
module ietf-ospf-sr-mpls {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls";
  prefix ospf-sr-mpls;

  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types";
  }
  import ietf-routing-types {
    prefix rt-types;
    reference
      "RFC 8294: Common YANG Data Types for the Routing Area";
  }
  import iana-routing-types {
    prefix iana-rt-types;
    reference
      "RFC 8294: Common YANG Data Types for the Routing Area";
  }
  import ietf-routing {
    prefix rt;
    reference
      "RFC 8349: A YANG Data Model for Routing
                 Management (NMDA Version)";
  }
  import ietf-segment-routing-common {
    prefix sr-cmn;
    reference
      "RFC 9020: YANG Data Model for Segment Routing";
  }
  import ietf-segment-routing-mpls {
    prefix sr-mpls;
    reference
      "RFC 9020: YANG Data Model for Segment Routing";
  }
  import ietf-ospf {
    prefix ospf;
    reference
      "RFC 9129: YANG Data Model for the OSPF Protocol";
  }
  import ietf-ospfv3-extended-lsa {
    prefix ospfv3-e-lsa;
    reference
      "RFC 9587: YANG Data Model for OSPFv3 Extended LSAs";
  }

  organization
    "IETF LSR - Link State Routing Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/lsr/>
     WG List:  <mailto:lsr@ietf.org>

     Author:   Yingzhen Qu
               <mailto:yingzhen.ietf@gmail.com>
     Author:   Acee Lindem
               <mailto:acee.ietf@gmail.com>
     Author:   Derek Yeung
               <mailto:derek@arrcus.com>
     Author:   Jeffrey Zhang
               <mailto:zzhang@juniper.net>
     Author:   Ing-Wher Chen
               <mailto:ingwherchen@mitre.org>";
  description
    "This YANG module defines the generic configuration
     and operational state for OSPF Segment Routing (SR).

     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.

     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).

     All revisions of IETF and IANA published modules can be found
     at the YANG Parameters registry
     (https://www.iana.org/assignments/yang-parameters).

     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.

     This version of this YANG module is part of RFC XXXX; 9903; see
     the RFC itself for full legal notices.";

  // RFC Ed.: Replace XXXX with actual RFC number and remove
  // this note

  revision 2025-05-09 2025-11-21 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: 9903: A YANG Data Model for OSPF Segment Routing for
       over the MPLS Data Plane";
  }

  // RFC Ed.: Replace XXXX with actual RFC number.
  // Also, replace '2025-04-14' with the module publication date
  // in the format (YYYY-MM-DD) and remove this note.

  feature remote-lfa-sr {
    description
      "Enhance rLFA Remote Loop-Free Alternate (RLFA) to use an SR path.";
    reference
      "RFC 8102: Remote-LFA Node Protection and Manageability";
  }

  feature ti-lfa {
    description
      "Topology-Independent
      "Topology Independent Loop-Free Alternate (TI-LFA)
       computation using segment routing.";
    reference
      "draft-ietf-rtgwg-segment-routing-ti-lfa:
       Topology-Independent
      "RFC 9855: Topology Independent Fast Reroute using Using Segment
       Routing";
  }

  identity prefix-sid-flag {
    description
      "Base identity for prefix SID sub-TLV Prefix-SID Sub-TLV flags.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity np-flag {
    base prefix-sid-flag;
    description
      "No-PHP (No Penultimate Hop-Popping) flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity m-flag {
    base prefix-sid-flag;
    description
      "Mapping server flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity e-flag {
    base prefix-sid-flag;
    description
      "Explicit-NULL flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity v-flag {
    base prefix-sid-flag;
    description
      "Value/Index flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity l-flag {
    base prefix-sid-flag;
    description
      "Local flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 6";
  }

  identity extended-prefix-range-flag {
    description
      "Base identity for extended prefix range Extended Prefix Range TLV flags.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 4
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 5";
  }

  identity ia-flag {
    base extended-prefix-range-flag;
    description
      "Inter-Area flag.  Note that this is only applicable to OSPFv2
       since OSPFv3 advertises separate Inter-Area extended-LSA.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 4";
  }

  identity adj-sid-flag {
    description
      "Base identity for Adj-SID sub-TLV Sub-TLV flags.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  identity b-flag {
    base adj-sid-flag;
    description
      "Backup flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  identity vi-flag {
    base adj-sid-flag;
    description
      "Value/Index flag - corresponds to V-Flag in references.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  identity lg-flag {
    base adj-sid-flag;
    description
      "Local/Global flag - corresponds to L-flag L-Flag in references.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  identity g-flag {
    base adj-sid-flag;
    description
      "Group flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  identity p-flag {
    base adj-sid-flag;
    description
      "Persistent flag.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 6
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 7";
  }

  /* Groupings */

  grouping sid-tlv-encoding {
    description
      "SID TLV Encoding - 20-bit label or 32-bit SID index whose
       interpretation is dependent on the TLV length (3 for an
       MPLS label or 4 for a 32-bit value)  or the TLV V-Flag and
       L-Flag settings:

        If the V-Flag is set to 0 and L-Flag is set to 0:
        The SID/Index/Label field is a 4-octet index defining
        the offset in the SID/Label space advertised by this
        router.

        If the V-Flag is set to 1 and L-Flag is set to 1:
        The
        ID/Index/Label SID/Index/Label field is a 3-octet local label where the
        20 rightmost bits are used for encoding the label value.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing, Section 2.1
       RFC 8665: OSPF Extensions for Segment Routing, Section 5
       RFC 8666: OSPFv3 Extensions for Segment Routing, Section 3";
    choice sid {
      case sid-label {
        leaf label-value {
          type uint32 {
            range "0 .. 1048575";
          }
          description
            "A 20-bit MPLS Label"; label.";
        }
      }
      case sid-index {
        leaf index-value {
          type uint32;
          description
            "Index into a label space advertised by this router.";
        }
      }
      description
        "Choice of either a 20-bit MPLS label or 32-bit index into
         an advertised label space.";
    }
  }

  grouping ospfv2-prefix-sid-sub-tlvs {
    description
      "OSPFv2 Prefix Segment ID (SID) sub-TLVs."; Sub-TLVs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 5)"; Routing, Section 5";
    container prefix-sid-sub-tlvs {
      description
        "Prefix SID sub-TLV.";
        "Prefix-SID Sub-TLV.";
      list prefix-sid-sub-tlv {
        description
          "Prefix SID sub-TLV.";
          "Prefix-SID Sub-TLV.";
        container prefix-sid-flags {
          leaf-list flag {
            type identityref {
              base prefix-sid-flag;
            }
            description
              "Prefix SID
              "Prefix-SID Sub-TLV flags.";
          }
          description
            "Segment Identifier (SID) Flags."; flags.";
        }
        leaf mt-id {
          type uint8 {
            range "0 .. 127";
          }
          description
            "Multi-topology ID.";
          reference
            "RFC 4915: Multi-Topology (MT) Routing in OSPF";
        }
        leaf algorithm {
          type identityref {
            base sr-cmn:prefix-sid-algorithm;
          }
          description
            "Algorithm associated with the prefix-SID."; Prefix-SID.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping ospfv2-extended-prefix-range-tlvs {
    description
      "OSPFv2 Extended prefix range Prefix Range TLV grouping.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 4)"; Routing, Section 4";
    container extended-prefix-range-tlvs {
      description
        "List of range of prefixes.";
      list extended-prefix-range-tlv {
        description
          "Range of prefixes.";
        leaf prefix-length {
          type uint8;
          description
            "Length of prefix in bits.";
        }
        leaf af {
          type iana-rt-types:address-family;
          description
            "Address family for the prefix.";
        }
        leaf range-size {
          type uint16;
          description
            "Number of prefixes covered by the
             advertisement.";
        }
        container extended-prefix-range-flags {
          leaf-list flag {
            type identityref {
              base extended-prefix-range-flag;
            }
            description
              "Extended prefix range Prefix Range TLV flags.";
          }
          description
            "Extended Prefix Range TLV flags.";
        }
        leaf prefix {
          type inet:ipv4-prefix;
          description
            "IPv4 prefix.";
        }
        uses ospfv2-prefix-sid-sub-tlvs;
        uses ospf:unknown-tlvs;
      }
    }
  }

  grouping ospfv2-adj-sid-sub-tlvs {
    description
      "OSPFv2 Adj-SID sub-TLV Sub-TLV grouping.";
    container adj-sid-sub-tlvs {
      description
        "Adj-SID optional sub-TLVs.";
      list adj-sid-sub-tlv {
        description
          "List of Adj-SID sub-TLVs."; Sub-TLVs.";
        container adj-sid-flags {
          leaf-list flag {
            type identityref {
              base adj-sid-flag;
            }
            description
              "Adj-SID sub-TLV Sub-TLV flags.";
          }
          description
            "Adj-SID sub-TLV Sub-TLV flags.";
        }
        leaf mt-id {
          type uint8 {
            range "0 .. 127";
          }
          description
            "Multi-topology ID.  Topologies range from 0-127 and
             return of any other value would indicate an error.";
          reference
            "RFC 4915: Multi-Topology (MT) Routing in OSPF";
        }
        leaf weight {
          type uint8;
          description
            "Weight used for load-balancing.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping ospfv2-lan-adj-sid-sub-tlvs {
    description
      "OSPFv2 LAN Adj-SID sub-TLV Sub-TLV grouping.";
    container lan-adj-sid-sub-tlvs {
      description
        "LAN Adj-SID optional sub-TLVs.";
      reference
        "RFC 8665: OSPF Extensions for Segment Routing
         (Section 6)"; Routing, Section 6";
      list lan-adj-sid-sub-tlv {
        description
          "List of LAN Adj-SID sub-TLVs."; Sub-TLVs.";
        container lan-adj-sid-flags {
          leaf-list flag {
            type identityref {
              base adj-sid-flag;
            }
            description
              "LAN Adj-SID sub-TLV Sub-TLV flags.";
          }
          description
            "LAN Adj-SID sub-TLV Sub-TLV flags.";
        }
        leaf mt-id {
          type uint8 {
            range "0 .. 127";
          }
          description
            "Multi-topology ID.  Topologies range from 0-127 and
             return of any other value would indicate an error.";
          reference
            "RFC 4915: Multi-Topology (MT) Routing in OSPF";
        }
        leaf weight {
          type uint8;
          description
            "Weight used for load-balancing.";
        }
        leaf neighbor-router-id {
          type rt-types:router-id;
          description
            "Neighbor router ID.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping sr-algorithm-tlv {
    description
      "SR algorithm
      "SR-Algorithm TLV grouping.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 3.1)"; Routing, Section 3.1";
    container sr-algorithm-tlv {
      description
        "All SR algorithm SR-Algorithm TLVs.";
      leaf-list sr-algorithm {
        type identityref {
          base sr-cmn:prefix-sid-algorithm;
        }
        description
          "Segment Routing (SR) algorithms that the router is
           currently using.";
      }
    }
  }

  grouping sid-range-tlvs {
    description
      "SID Range TLV grouping.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 3.2)"; Routing, Section 3.2";
    container sid-range-tlvs {
      description
        "List of SID range Range TLVs.";
      list sid-range-tlv {
        description
          "SID range Range TLV.";
        leaf range-size {
          type rt-types:uint24;
          description
            "SID range.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping local-block-tlvs {
    description
      "The SR local block Local Block TLV contains the
       range of labels reserved for local SIDs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 3.3)"; Routing, Section 3.3";
    container local-block-tlvs {
      description
        "List of SRLB Segment Routing Local Block (SRLB) TLVs.";
      list local-block-tlv {
        description
          "SRLB TLV.";
        leaf range-size {
          type rt-types:uint24;
          description
            "SID range.  The return of a zero value would indicate
             an error.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping srms-preference-tlv {
    description
      "The SR Mapping Server (SRMS) preference Preference TLV is
       used to advertise a preference associated with
       the node that acts as an SR Mapping Server.  SR
       Mapping Server advertisements with a higher
       preference value are preferred over those with
       a lower preference value.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 3.4)"; Routing, Section 3.4";
    container srms-preference-tlv {
      description
        "SRMS Preference TLV.";
      leaf preference {
        type uint8;
        description
          "SRMS preference Preference TLV, value from 0 to 255 with
           255 being the most preferred.";
      }
    }
  }

  grouping ospfv3-prefix-sid-sub-tlvs {
    description
      "OSPFv3 Prefix Segment ID (SID) sub-TLVs."; Prefix-SID Sub-TLVs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    container prefix-sid-sub-tlvs {
      description
        "Prefix SID sub-TLV.";
        "Prefix-SID Sub-TLV.";
      list prefix-sid-sub-tlv {
        description
          "Prefix SID sub-TLV.";
          "Prefix-SID Sub-TLV.";
        container ospfv3-prefix-sid-flags {
          leaf-list flag {
            type identityref {
              base prefix-sid-flag;
            }
            description
              "Prefix SID sub-TLV
              "Prefix-SID Sub-TLV flags.";
          }
          description
            "Segment Identifier (SID) Flags."; flags.";
        }
        leaf algorithm {
          type identityref {
            base sr-cmn:prefix-sid-algorithm;
          }
          description
            "Algorithm associated with the prefix-SID."; Prefix-SID.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping ospfv3-extended-prefix-range-tlvs {
    description
      "OSPFv3 Extended prefix range Prefix Range TLV grouping.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 5)"; Routing, Section 5";
    container ospfv3-extended-prefix-range-tlvs {
      description
        "List of extended prefix range Extended Prefix Range TLVs.";
      list extended-prefix-range-tlv {
        description
          "Range of prefixes.";
        leaf prefix-length {
          type uint8;
          description
            "Length of prefix in bits.";
        }
        leaf af {
          type iana-rt-types:address-family;
          description
            "Address family for the prefix.";
        }
        leaf range-size {
          type uint16;
          description
            "Number of prefixes covered by the advertisement.
             The return of a value of zero would indicate an error.";
        }
        leaf prefix {
          type inet:ip-prefix;
          description
            "IPv4 or IPv6 prefix.";
        }
        uses ospfv3-prefix-sid-sub-tlvs;
        uses ospf:unknown-tlvs;
      }
    }
  }

  grouping ospfv3-adj-sid-sub-tlvs {
    description
      "OSPFv3 Adj-SID sub-TLV Sub-TLV grouping.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 7)"; Routing, Section 7";
    container adj-sid-sub-tlvs {
      description
        "Adj-SID optional sub-TLVs.";
      list adj-sid-sub-tlv {
        description
          "List of Adj-SID sub-TLVs."; Sub-TLVs.";
        container adj-sid-flags {
          leaf-list flag {
            type identityref {
              base adj-sid-flag;
            }
            description
              "Adj-SID sub-tlv Sub-tlv flags.";
          }
          description
            "Adj-sid sub-tlv
            "Adj-SID Sub-tlv flags.";
        }
        leaf weight {
          type uint8;
          description
            "Weight used for load-balancing.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping ospfv3-lan-adj-sid-sub-tlvs {
    description
      "OSPFv3 LAN Adj-SID sub-TLV Sub-TLV grouping.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 7)"; Routing, Section 7";
    container lan-adj-sid-sub-tlvs {
      description
        "LAN Adj-SID optional sub-TLVs.";
      list lan-adj-sid-sub-tlv {
        description
          "List of LAN Adj-SID sub-TLVs."; Sub-TLVs.";
        container lan-adj-sid-flags {
          leaf-list flag {
            type identityref {
              base adj-sid-flag;
            }
            description
              "LAN Adj-SID sub-TLV Sub-TLV flags.";
          }
          description
            "LAN Adj-SID sub-TLV Sub-TLV flags.";
        }
        leaf weight {
          type uint8;
          description
            "Weight used for load-balancing.";
        }
        leaf neighbor-router-id {
          type rt-types:router-id;
          description
            "Neighbor router ID.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  /*
   * Augmentations for OSPF SR MPLS SR-MPLS Configuration (read-write)
   * data nodes.
   */

  augment "/rt:routing/rt:control-plane-protocols"
        + "/rt:control-plane-protocol/ospf:ospf" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf')" {
      description
        "This augments the OSPF routing protocol when used.";
    }
    description
      "This augments the OSPF protocol configuration with segment
       routing Segment
       Routing over the MPLS data plane.  The following semantic
       validation is to be performed for the configuration data:
        - Assure the binding policies prefixes do not overlapp."; overlap.";
    reference
      "RFC 9020 - 9020: YANG Data Model for Segment Routing";
    uses sr-mpls:sr-control-plane;
    container protocol-srgb {
      if-feature "sr-mpls:protocol-srgb";
      uses sr-cmn:srgb;
      description
        "Per-protocol SRGB.";
    }
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/ospf:ospf/"
        + "ospf:areas/ospf:area" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf') and "
       + "/rt:routing/rt:control-plane-protocols"
       + "/rt:control-plane-protocol/ospf:ospf"
       + "/ospf-sr-mpls:segment-routing/"
       + "ospf-sr-mpls:enabled = 'true'" {
      description
        "This augments the OSPF area configuration when segment
         routing Segment
         Routing is enabled at the OSPF instance level.";
    }
    container segment-routing {
      presence "When present segment routing present, Segment Routing over MPLS is enabled
                for the area.";
      description
        "OSPF area level segment routing Segment Routing configuration. Enable
         segment routing  Enables
         Segment Routing over MPLS on all interfaces interfaces, and enables
         advertisement of Link State Advertisements (LSAs) and TLVs
         supporting segment routing Segment Routing over MPLS"; MPLS.";
    }
    description
      "This augments the OSPF protocol area configuration with
       segment routing.";
       Segment Routing.";
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/ospf:ospf/"
        + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf') and "
       + "/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/ospf:ospf/"
       + "ospf:areas/ospf:area/ospf-sr-mpls:segment-routing" {
      description
        "This augments the OSPF interface configuration when used.";
    }
    description
      "This augments the OSPF protocol interface
       configuration with segment routing."; Segment Routing.";
    reference
      "RFC 9020 - 9020: YANG Data Model for Segment Routing";
    uses sr-mpls:igp-interface {
      augment "segment-routing/adjacency-sid/adj-sids" {
        when "((../../../ospf:interface-type = 'broadcast') or
              (../../../ospf:interface-type = 'non-broadcast'))" {
          description
            "This augments broadcast and non-broadcast multi-access
             interface segment routing Segment Routing interface configuration.";
        }
        description
          "This augments LAN interface adj-sid with neighbor-id.";
        leaf neighbor-id {
          type inet:ip-address;
          mandatory true;
          description
            "Neighbor's Router ID, IPv4 address, or IPv6 address.
             Specification is optional and, if specified, SHOULD
             specify a neighbor reachable via the interface.";
        }
      }
    }
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/ospf:ospf/"
        + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface/"
        + "ospf:fast-reroute/ospf:lfa" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf')" {
      description
        "This augments the OSPF routing protocol when used.";
    }
    description
      "This augments the OSPF protocol IP-FRR IP Fast Reroute (IP-FRR) with
       TI-LFA.";
    container ti-lfa {
      if-feature "ti-lfa";
      description
        "Topology-Independent
        "Topology Independent Loop Free Alternate
         (TI-LFA) support.";
      reference
        "draft-ietf-rtgwg-segment-routing-ti-lfa:
         Topology-Independent
        "RFC 9855: Topology Independent Fast Reroute using Using Segment
         Routing";
      leaf enabled {
        type boolean;
        default "false";
        description
          "Enable TI-LFA computation.";
      }
      container selection-tie-breakers {
        container node-protection {
          presence "Presence of container enables the node
                    protection tie-breaker.";
          leaf priority {
            type uint8;
            default "128";
            description
              "Priority for node protection tie-breaker with
               a lower priority being more preferred.  By default,
               the priority is in the middle of the priority range.";
          }
          description
            "Enable node protection as a TI-LFA path
             selection tie-breaker.  A path providing node
             protection will be selected over one that
             doesn't provide node protection.";
        }
        container srlg-disjoint {
          presence "Presence of container enables the SRLG
                    disjoint tie-breaker"; tie-breaker.";
          leaf priority {
            type uint8;
            default "128";
            description
              "Priority for SRLG Shared Risk Link Group (SRLG)
               disjoint tie-breaker with a lower priority being
               more preferred.  By default, the priority is in the
               middle of the priority range.";
          }
          description
            "Enable SRLG (Sharsed Resource Link Group) disjoint as a TI-LFA path selection
             tie-breaker.  A path providing a node with a disjoint
             path for SRLG links from the primary path will be
             selected over
             one a path that doesn't provide an SRLG
             disjoint path.";
        }
        description
          "Configure path selection tie-breakers and their
           respective priorities for the TI-LFA computation.
           multiple
           Multiple tie-breakers and priorities configured may be configured.";
      }
    }
  }

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/ospf:ospf/"
        + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface/"
        + "ospf:fast-reroute/ospf:lfa/ospf:remote-lfa" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf')" {
      description
        "This augments the OSPF routing protocol when used.";
    }
    description
      "This augments the OSPF protocol IP-FRR with remote Remote LFA.";
    reference
      "draft-ietf-rtgwg-segment-routing-ti-lfa:
       Topology-Independent
      "RFC 9855: Topology Independent Fast Reroute using Using Segment
       Routing";
    leaf use-segment-routing-path {
      if-feature "remote-lfa-sr";
      type boolean;
      default "false";
      description
        "Force remote Remote LFA to use segment routing a Segment Routing path instead of an
         LDP path.  The value of this leaf is in effect only when
         remote-lfa is enabled.";
    }
  }

  /* Operational states */

  augment "/rt:routing/rt:control-plane-protocols/"
        + "rt:control-plane-protocol/ospf:ospf/"
        + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface/"
        + "ospf:neighbors/ospf:neighbor" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospf')" {
      description
        "This augments the OSPF routing protocol when used.";
    }
    description
      "This augments the OSPF interface adjancency-sid adjacency-sid state.";
    list adjacency-sid {
      description
        "List of adjacency Segment IDs.";
      leaf value {
        type uint32;
        description
          "Value of the Adj-SID.";
      }
      leaf weight {
        type uint8;
        description
          "Weight associated with the adjacency SID.";
      }
      leaf protection-requested {
        type boolean;
        description
          "Describe if the adjacency SID is protected.";
      }
    }
  }

  /*
   * Augmentations for read-only data nodes corresponding to Segment
   * Routing encodings in OSPFv2 and OSPFv3 Link State Advertisements
   * (LSAs) in OSPF Link State Databases (LSDBs) at the instance,
   * area, and interface level.
   */
  /* Augmentations for OSPFv2 LSAs. */

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/"
        + "ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/"
        + "ospf:extended-prefix-opaque" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR Extended Prefix Range TLV in OSPFv2 Type 10 (area-scoped)
       Extended Prefix Opaque LSAs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 4)"; Routing, Section 4";
    uses ospfv2-extended-prefix-range-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/"
        + "ospf:extended-prefix-opaque" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR Extended Prefix Range TLV in OSPFv2 Type 11 (AS-scoped)
       Extended Prefix Opaque LSAs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
       (Section 4)"; Routing, Section 4";
    uses ospfv2-extended-prefix-range-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/"
        + "ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/"
        + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR Prefix-SID sub-TLVs Sub-TLVs for OSPFv2 Extended Prefix TLVs
       in OSPFv2 Type 10 (area-scoped) Extended Prefix Opaque LSAs.";
    uses ospfv2-prefix-sid-sub-tlvs;
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 5)"; Routing, Section 5";
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/"
        + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR Prefix-SID sub-TLVs Sub-TLVs for OSPFv2 Extended Prefix TLVs
       in OSPFv2 Type 11 (AS-scoped) Extended Prefix Opaque LSAs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 5)"; Routing, Section 5";
    uses ospfv2-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/"
        + "ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/"
        + "ospf:extended-link-opaque/ospf:extended-link-tlv" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR TLVs for OSPFv2 Extended Link TLV in OSPFv2 Type 10
       (area-scoped) Extended Link Opaque LSAs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 6)"; Routing, Section 6";
    uses ospfv2-adj-sid-sub-tlvs;
    uses ospfv2-lan-adj-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/"
        + "ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR TLVs for OSPFv2 Router Information Type 10 (area-scoped)
       Opaque LSAs";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 3)"; Routing, Section 3";
    uses sr-algorithm-tlv;
    uses sid-range-tlvs;
    uses local-block-tlvs;
    uses srms-preference-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/"
        + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv2')" {
      description
        "This augmentation is only valid for OSPFv2.";
    }
    description
      "SR TLVs for OSPFv2 Router Information Type 11 (AS-scoped)
       Opaque LSAs"; LSAs.";
    reference
      "RFC 8665: OSPF Extensions for Segment Routing
        (Section 3)"; Routing, Section 3";
    uses sr-algorithm-tlv;
    uses sid-range-tlvs;
    uses local-block-tlvs;
    uses srms-preference-tlv;
  }

  /* Augmentations for OSPFv3 LSAs. */

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospf:router-information" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR-specific TLVs for OSPFv3 Router Information LSA
       (area-scoped).";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 4)"; Routing, Section 4";
    uses sr-algorithm-tlv;
    uses sid-range-tlvs;
    uses local-block-tlvs;
    uses srms-preference-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/"
        + "ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospf:router-information" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR-specific TLVs for OSPFv3 Router Information LSA
       (AS-scoped).";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 4)"; Routing, Section 4";
    uses sr-algorithm-tlv;
    uses sid-range-tlvs;
    uses local-block-tlvs;
    uses srms-preference-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-intra-area-prefix" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    uses ospfv3-extended-prefix-range-tlvs;
    description
      "SR Extended Prefix Range TLVs in OSPFv3
       E-Intra-Area-Prefix LSAs.";
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-inter-area-prefix" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Extended Prefix Range TLVs in OSPFv3
       E-Inter-Area-Prefix LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 5)"; Routing, Section 5";
    uses ospfv3-extended-prefix-range-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-as-external" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Extended Prefix Range TLVs in OSPFv3 E-AS-External LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 5)"; Routing, Section 5";
    uses ospfv3-extended-prefix-range-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-nssa" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Extended Prefix Range TLVs in OSPFv3 E-NSSA LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 5)"; Routing, Section 5";
    uses ospfv3-extended-prefix-range-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:interfaces/"
        + "ospf:interface/"
        + "ospf:database/ospf:link-scope-lsa-type/"
        + "ospf:link-scope-lsas/ospf:link-scope-lsa/"
        + "ospf:version/ospf:ospfv3/ospf:ospfv3/"
        + "ospf:body/ospfv3-e-lsa:e-link/"
        + "ospfv3-e-lsa:e-link-tlvs/ospfv3-e-lsa:intra-prefix-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Prefix-SID Sub-TLV in OSPFv3 Intra-Area
       Prefix Intra-Area-Prefix
       TLV for OSPFv3 E-Link LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    uses ospfv3-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-intra-area-prefix/"
        + "ospfv3-e-lsa:e-intra-prefix-tlvs/"
        + "ospfv3-e-lsa:intra-prefix-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3
         E-Router LSAs"; LSAs.";
    }
    description
      "SR Prefix-SID Sub-TLV in OSPFv3 Intra-Area
       Prefix Intra-Area-Prefix
       TLV for OSPFv3 E-Intra-Area-Prefix LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    uses ospfv3-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-inter-area-prefix/"
        + "ospfv3-e-lsa:e-inter-prefix-tlvs/"
        + "ospfv3-e-lsa:inter-prefix-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Prefix-SID Sub-TLV in OSPFv3 Link-Scoped Intra-Area
       Prefix Intra-Area-Prefix
       TLV for OSPFv3 E-Inter-Area-Prefix LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    uses ospfv3-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:database/"
        + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/"
        + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-as-external/"
        + "ospfv3-e-lsa:e-external-tlvs/"
        + "ospfv3-e-lsa:external-prefix-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Prefix-SID Sub-TLV in OSPFv3 External Prefix External-Prefix TLV
       for OSPFv3 E-AS-External LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    uses ospfv3-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-nssa/"
        + "ospfv3-e-lsa:e-external-tlvs/"
        + "ospfv3-e-lsa:external-prefix-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3.";
    }
    description
      "SR Prefix-SID Sub-TLV in OSPFv3 External Prefix External-Prefix TLV
       for OSPFv3 E-NSSA LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 6)"; Routing, Section 6";
    uses ospfv3-prefix-sid-sub-tlvs;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol/"
        + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"
        + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/"
        + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/"
        + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-router/"
        + "ospfv3-e-lsa:e-router-tlvs/ospfv3-e-lsa:link-tlv/"
        + "ospfv3-e-lsa:sub-tlvs" {
    when "derived-from(/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:type, 'ospf:ospfv3')" {
      description
        "This augmentation is only valid for OSPFv3
         E-Router LSAs"; LSAs.";
    }
    description
      "SR Sub-TLVs in OSPFv3 link-tlv for OSPFv3 E-Router LSAs"; LSAs.";
    reference
      "RFC 8666: OSPFv3 Extensions for Segment Routing
       (Section 7)"; Routing, Section 7";
    uses ospfv3-adj-sid-sub-tlvs;
    uses ospfv3-lan-adj-sid-sub-tlvs;
  }
}
<CODE ENDS>
]]></artwork>
]]></sourcecode>
</figure>
</section>

<section anchor="Security" numbered="true" toc="default">  <name>Security Considerations</name>

<!--[rfced] FYI, we have made some updates to the Security Considerations to
match Section 3.7 of draft-ietf-netmod-rfc8407bis-28. Please let us know
if any further updates are needed. Specifically:

- Should this sentence from the template be added? "There are no particularly sensitive RPC or action operations."

-->

<!-- DNE begins -->
<t>This section is modeled after the template described in <xref target="I-D.ietf-netmod-rfc8407bis" section="3.7" sectionFormat="of"/>.</t>

<t>
   The ietf-ospf-sr-mpls "ietf-ospf-sr-mpls" YANG module defines a data model that is
   designed to be accessed via YANG-based management protocols, such as
   NETCONF <xref target="RFC6241"/> and RESTCONF <xref target="RFC8040"/>.
   These YANG-based management protocols (1) have to use a secure transport layer (e.g., SSH
   <xref target="RFC4252"/>, TLS <xref target="RFC8446"/>, and
   QUIC <xref target="RFC9000"/>) and (2) have to use mutual authentication.
 </t>
 <t>
    The Network Configuration Access Control Model (NACM) <xref target="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>
   There are a number of data nodes defined in this YANG module that are
   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 following subtrees and data nodes
   have particular sensitivities/vulnerabilities:
 </t>
 <!-- DNE ends -->
 <ul empty="true" spacing="normal">
   <li>
     /ospf:ospf/segment-routing/enabled
   <li>/ospf:ospf/segment-routing/enabled - Modification to the
     enablement for SR could result in a Denial-of-Service (DoS)
     attack. If an attacker disables SR, it will cause traffic disruption.
   </li>
   <li>
     /ospf:ospf/segment-routing/bindings disruption.</li>
     <li>/ospf:ospf/segment-routing/bindings - Modification to the local
     bindings could result in a Denial-of-Service (DoS) attack.
   </li>
   <li>
     /ospf:ospf/protocol-srgb attack.</li>
     <li>/ospf:ospf/protocol-srgb - Modification of the protocol SRGB
     could be used to mount a DoS attack. For example, if the protocol
     SRBG
     SRGB size is reduced to a very small value, a lot of existing
     segments could no longer be installed installed, leading to a traffic disruption.
   </li>
   <li>
     /ospf:interfaces/ospf:interface/segment-routing disruption.</li>
     <li>/ospf:interfaces/ospf:interface/segment-routing - Modification of the
     Adjacency Segment Identifier (Adj-SID) could be used to mount a
     DoS attack. Change of an Adj-SID could be used to redirect traffic.
   </li>
   <li>
     /ospf:interfaces/ospf:interface/ospf:fast-reroute/ti-lfa traffic.</li>
     <li>/ospf:interfaces/ospf:interface/ospf:fast-reroute/ti-lfa - Modification
     of the TI-LFA enablement could lead to traffic disruption.
   </li> disruption.</li>
 </ul>
 <!-- DNE begins -->
  <t>
    Some of the readable data nodes in this YANG module may be considered
    sensitive or vulnerable in some network environments.  It is thus
    important to control read access (e.g., via get, get-config, or
    notification) to these data nodes. Specifically, the following
    subtrees and data nodes have particular sensitivities/
    vulnerabilities: sensitivities/vulnerabilities:
  </t>
<!-- DNE ends -->

 <ul empty="true" spacing="normal">
   <li>
     The "ietf-ospf-sr-mpls" module ietf-ospf-sr-mpls augments the base OSPF module Link State
     Database (LSDB) with various TLVs. Knowledge of these data nodes
     can be used to attack other routers in the OSPF domain. These attacks
     are documented in <xref target="RFC9129"/>.
   </li>
   <li>
     Knowledge of the Prefix and Adjacency SIDs advertised in LSAs
     could facilitate a targeted attack on the data-plane data plane by knowing the
     topology and path for MPLS segment-routed packets. Examples include
     the OSPFv2 extended-prefix-opaque-LSA/prefix-sid-sub-tlvs and
     OSPFv3 e-router-tlvs/link-tlv/sub-tlvs/ospfv3-lan-adj-sid-sub-tlvs.
   </li>
   <li>
     Knowledge of Prefix and Adjaceny Adjacency SIDs may also divulge a view of the segment
     routing Segment
     Routing network topology architecture architecture, which may be considered a proprietary
     asset.
   </li>
   <li>
     Knowledge of the advertised SID/Label Range TLVs,
     SR Local Block TLVs TLVs, and Segment Routing Mapping Server (SRMS) TLVs may facilitate
     a Denial of Service (DoS) attack on the advertising node's SR
     and SRMS functionality. Examples include augmentations to the
     OSPFv2 ri-opaque/sid-range-tlvs and OSPFv3 router-information/local-block-tlvs.
   </li>
 </ul>
<!-- DNE begins -->
 <t>
   This YANG module uses groupings from other YANG modules that
   define nodes that may be considered sensitive or vulnerable
   in network environments. Refer to the Security Considerations
   of <xref target="RFC9020"/> for information as to which nodes may
   be considered sensitive or vulnerable in network environments.
 </t>
</section>
    <section anchor="Acknowledgements" numbered="true" toc="default">
      <name>Acknowledgements</name>
      <t>
        The authors wish to thank Dean Bogdanovic and Kiran Koushik Agrahara Sreenivasa
        for their YANG module discussions.
      </t>
      <t>
        The authors wish to thank Yi Yang, Alexander Clemm,
        Gaurav Gupta, Ladislav Lhotka, Stephane Litkowski,
        Greg Hankins, Manish Gupta, Alan Davey, Divakaran Baskaran, Reshad Rahman, Tom Petch,
        and Corey Bonnell for their thorough reviews and helpful comments.
      </t>
      <t>
        The authors wish to thank Julien Meuric for a very meticulous Routing Directorate review.
      </t>
      <t>
        The authors wish to thank Mohamed Boucadair and Ketan Talaulikar
        for extensive AD reviews for the IESG Telechat. Thanks to Eric Vyncke and Mahesh
        Jethanandani for review comments.
      </t>
      <t>
        Author affiliation with The MITRE Corporation is provided for
        identification purposes only, and is not intended to convey or imply MITRE's
        concurrence with, or support for, the positions, opinions or viewpoints
        expressed.  MITRE has agreed to this document for Public Release,
        Distribution Unlimited, with Public Release Case Number 18-3281. This
        approval allows the MITRE employee to release contributions externally and
        does not assert authority to publish.
      </t>
<!-- DNE ends -->
</section>
    <section anchor="IANA" toc="default" numbered="true">
      <name>IANA Considerations</name>
      <t>
        This document registers a URI in the IETF "IETF XML registry Registry"
        <xref target="RFC3688" format="default"/>.  Following the format in <xref
        target="RFC3688" format="default"/>,
        the following registration is requested to be has been made:
      </t>
      <artwork name="" type="" align="left" alt=""><![CDATA[
      URI: urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls
      Registrant Contact: The IESG.
      XML: N/A,
      <dl spacing="compact" newline="false">
      <dt>URI:</dt><dd>urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls</dd>
      <dt>Registrant Contact:</dt><dd>The IESG.</dd>
      <dt>XML:</dt><dd>N/A; the requested URI is an XML namespace.
      ]]></artwork> namespace.</dd>
      </dl>
      <t>
        This document registers a YANG module in the YANG "YANG Module Names Names"
        registry <xref target="RFC6020" format="default"/>.
      </t>
      <artwork name="" type="" align="left" alt=""><![CDATA[
      name: ietf-ospf-sr-mpls
      namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls
      prefix: ospf-sr-mpls
      maintained
      <dl spacing="compact" newline="false">
      <dt>Name:</dt><dd>ietf-ospf-sr-mpls</dd>
      <dt>Maintained by IANA? N
      reference: RFC XXXX
      ]]></artwork> IANA?:</dt><dd>N</dd>
      <dt>Namespace:</dt><dd>urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls</dd>
      <dt>Prefix:</dt><dd>ospf-sr-mpls</dd>
      <dt>Reference:</dt><dd>RFC 9903</dd>
      </dl>
    </section>
  </middle>
  <!--  *****BACK MATTER ***** -->

  <back>
    <!-- References split into informative and normative -->

    <!-- There are 2 ways to insert reference entries from the citation libraries:
         1. define an ENTITY at the top, and use "ampersand character"RFC2629; here (as shown)
         2. simply use a PI "less than character"?rfc include="reference.RFC.2119.xml"?> here
         (for I-Ds: include="reference.I-D.narten-iana-considerations-rfc2434bis.xml")

Both are cited textually in the same manner: by using xref elements.
If you use the PI option, xml2rfc will, by default, try to find included files in the same
directory as the including file. You can also define the XML_LIBRARY environment variable
with a value containing a set of directories to search.  These can be either in the local
filing system or remote ones accessed by http (http://domain/dir/... ).-->
    <displayreference target="I-D.ietf-netmod-rfc8407bis" to="YANG-GUIDE"/>
    <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.2328.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2328.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3688.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3688.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4915.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4915.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5340.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5340.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6020.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6020.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6991.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6991.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7770.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7770.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7684.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7684.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7950.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7950.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8102.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8102.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.8294.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8294.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8341.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8341.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8362.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8362.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8349.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8349.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8665.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8665.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8666.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8666.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9020.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9020.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9129.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9129.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9587.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9587.xml"/>

<!-- draft-ietf-rtgwg-segment-routing-ti-lfa-21 companion doc published
as RFC 9855 as of 10/28/25
-->
         <xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-rtgwg-segment-routing-ti-lfa.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9855.xml"/>

      </references>
      <references>
        <name>Informative References</name>
        <!-- Here we use entities that we defined at the beginning. -->
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4252.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4252.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6241.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6241.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8040.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8040.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8340.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8340.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8342.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8342.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8446.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8446.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8792.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8792.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9000.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9000.xml"/>

<xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-netmod-rfc8407bis.xml"/>

      </references>
    </references>
    <section numbered="true" toc="default">
        <name>A Configuration Example</name>
        <t>The following is an XML example using the ietf-ospf-sr-mpls "ietf-ospf-sr-mpls" YANG module, module
           and RFC 9020.</t> <xref target="RFC9020"/>.</t>
        <t>Note: '\' line wrapping per <xref target="RFC8792" format="default"/>. </t>
        <artwork name="" type="" align="left" alt=""><![CDATA[
        <sourcecode type="xml"><![CDATA[
<?xml version='1.0' encoding='UTF-8'?>
  <routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <router-id>1.1.1.1</router-id>
    <control-plane-protocols>
      <control-plane-protocol>
        <type xmlns:ospf="urn:ietf:params:xml:ns:yang:ietf-ospf">\
          ospf:ospfv2</type>
        <name>OSPFv2</name>
        <ospf xmlns="urn:ietf:params:xml:ns:yang:ietf-ospf">
          <areas>
            <area>
              <area-id>0.0.0.0</area-id>
              <segment-routing xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-ospf-sr-mpls"></segment-routing>
              <interfaces>
                <interface>
                  <name>eth0</name>
                  <segment-routing xmlns="urn:ietf:params:xml:ns:\
                    yang:ietf-ospf-sr-mpls">
                    <adjacency-sid>
                      <adj-sids>
                        <value>3888</value>
                      </adj-sids>
                    </adjacency-sid>
                  </segment-routing>
                </interface>
              </interfaces>
            </area>
          </areas>
          <segment-routing xmlns="urn:ietf:params:xml:ns:yang:\
            ietf-ospf-sr-mpls">
            <enabled>true</enabled>
          </segment-routing>
          <protocol-srgb xmlns="urn:ietf:params:xml:ns:yang:\
            ietf-ospf-sr-mpls">
            <srgb>
              <lower-bound>4000</lower-bound>
              <upper-bound>5000</upper-bound>
            </srgb>
          </protocol-srgb>
        </ospf>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
  ]]></artwork>
  ]]></sourcecode>
      <t>The following is the same example using JSON format.</t>
      <artwork name="" type="" align="left" alt=""><![CDATA[
      <sourcecode type="json"><![CDATA[
{
  "ietf-routing:routing": {
    "router-id": "1.1.1.1",
    "control-plane-protocols": {
      "control-plane-protocol": [
        {
          "type": "ietf-ospf:ospfv2",
          "name": "OSPFv2",
          "ietf-ospf:ospf": {
            "areas": {
              "area": [
                {
                  "area-id": "0.0.0.0",
                  "interfaces": {
                    "interface": [
                      {
                        "name": "eth0",
                        "ietf-ospf-sr-mpls:segment-routing": {
                          "adjacency-sid": {
                            "adj-sids": [
                              {
                                "value": 3888
                              }
                            ]
                          }
                        }
                      }
                    ]
                  },
                  "ietf-ospf-sr-mpls:segment-routing": {}
                }
              ]
            },
            "ietf-ospf-sr-mpls:segment-routing": {
              "enabled": true
            },
            "ietf-ospf-sr-mpls:protocol-srgb": {
              "srgb": [
                {
                  "lower-bound": 4000,
                  "upper-bound": 5000
                }
              ]
            }
          }
        }
      ]
    }
  }
}
  ]]></artwork>
  ]]></sourcecode>
    </section>

<section numbered="true" toc="default"> <name>Full Tree Diagram</name>
<artwork align="left" name="" type="" alt=""><![CDATA[
<sourcecode type="yangtree"><![CDATA[
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf:
  +--rw segment-routing
  |  +--rw enabled?    boolean
  |  +--rw bindings {mapping-server}?
  |     +--rw advertise
  |     |  +--rw policies*   leafref
  |     +--rw receive?     boolean
  +--rw protocol-srgb {sr-mpls:protocol-srgb}?
     +--rw srgb* [lower-bound upper-bound]
        +--rw lower-bound    uint32
        +--rw upper-bound    uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area:
  +--rw segment-routing!
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:interfaces/ospf:interface:
  +--rw segment-routing
     +--rw adjacency-sid
        +--rw adj-sids* [value]
        |  +--rw value-type?    enumeration
        |  +--rw value          uint32
        |  +--rw protected?     boolean
        |  +--rw weight?        uint8
        |  +--rw neighbor-id    inet:ip-address
        +--rw advertise-adj-group-sid* [group-id]
        |  +--rw group-id    uint32
        +--rw advertise-protection?      enumeration
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:interfaces/ospf:interface
          /ospf:fast-reroute/ospf:lfa:
  +--rw ti-lfa {ti-lfa}?
     +--rw enabled?                  boolean
     +--rw selection-tie-breakers
        +--rw node-protection!
        |  +--rw priority?   uint8
        +--rw srlg-disjoint!
           +--rw priority?   uint8
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:interfaces/ospf:interface
          /ospf:fast-reroute/ospf:lfa/ospf:remote-lfa:
  +--rw use-segment-routing-path?   boolean {remote-lfa-sr}?
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:interfaces/ospf:interface/ospf:neighbors
          /ospf:neighbor:
  +--ro adjacency-sid* []
     +--ro value?                  uint32
     +--ro weight?                 uint8
     +--ro protection-requested?   boolean
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque
          /ospf:extended-prefix-opaque:
  +--ro extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?                 uint8
        +--ro af?
        |       iana-rt-types:address-family
        +--ro range-size?                    uint16
        +--ro extended-prefix-range-flags
        |  +--ro flag*   identityref
        +--ro prefix?                        inet:ipv4-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro mt-id?               uint8
        |     +--ro algorithm?           identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?   uint32
        |        +--:(sid-index)
        |           +--ro index-value?   uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2
          /ospf:body/ospf:opaque/ospf:extended-prefix-opaque:
  +--ro extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?                 uint8
        +--ro af?
        |       iana-rt-types:address-family
        +--ro range-size?                    uint16
        +--ro extended-prefix-range-flags
        |  +--ro flag*   identityref
        +--ro prefix?                        inet:ipv4-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro mt-id?               uint8
        |     +--ro algorithm?           identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?   uint32
        |        +--:(sid-index)
        |           +--ro index-value?   uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque
          /ospf:extended-prefix-opaque/ospf:extended-prefix-tlv:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro mt-id?               uint8
        +--ro algorithm?           identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?   uint32
           +--:(sid-index)
              +--ro index-value?   uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2
          /ospf:body/ospf:opaque/ospf:extended-prefix-opaque
          /ospf:extended-prefix-tlv:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro mt-id?               uint8
        +--ro algorithm?           identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?   uint32
           +--:(sid-index)
              +--ro index-value?   uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque
          /ospf:extended-link-opaque/ospf:extended-link-tlv:
  +--ro adj-sid-sub-tlvs
  |  +--ro adj-sid-sub-tlv* []
  |     +--ro adj-sid-flags
  |     |  +--ro flag*   identityref
  |     +--ro mt-id?               uint8
  |     +--ro weight?              uint8
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro lan-adj-sid-sub-tlvs
     +--ro lan-adj-sid-sub-tlv* []
        +--ro lan-adj-sid-flags
        |  +--ro flag*   identityref
        +--ro mt-id?                uint8
        +--ro weight?               uint8
        +--ro neighbor-router-id?   rt-types:router-id
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?    uint32
           +--:(sid-index)
              +--ro index-value?    uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque
          /ospf:ri-opaque:
  +--ro sr-algorithm-tlv
  |  +--ro sr-algorithm*   identityref
  +--ro sid-range-tlvs
  |  +--ro sid-range-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro local-block-tlvs
  |  +--ro local-block-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro srms-preference-tlv
     +--ro preference?   uint8
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2
          /ospf:body/ospf:opaque/ospf:ri-opaque:
  +--ro sr-algorithm-tlv
  |  +--ro sr-algorithm*   identityref
  +--ro sid-range-tlvs
  |  +--ro sid-range-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro local-block-tlvs
  |  +--ro local-block-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro srms-preference-tlv
     +--ro preference?   uint8
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3
          /ospf:body/ospf:router-information:
  +--ro sr-algorithm-tlv
  |  +--ro sr-algorithm*   identityref
  +--ro sid-range-tlvs
  |  +--ro sid-range-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro local-block-tlvs
  |  +--ro local-block-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro srms-preference-tlv
     +--ro preference?   uint8
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body
          /ospf:router-information:
  +--ro sr-algorithm-tlv
  |  +--ro sr-algorithm*   identityref
  +--ro sid-range-tlvs
  |  +--ro sid-range-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro local-block-tlvs
  |  +--ro local-block-tlv* []
  |     +--ro range-size?          rt-types:uint24
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro srms-preference-tlv
     +--ro preference?   uint8
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body
          /ospfv3-e-lsa:e-intra-area-prefix:
  +--ro ospfv3-extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?         uint8
        +--ro af?                    iana-rt-types:address-family
        +--ro range-size?            uint16
        +--ro prefix?                inet:ip-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro ospfv3-prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro algorithm?                 identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?         uint32
        |        +--:(sid-index)
        |           +--ro index-value?         uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body
          /ospfv3-e-lsa:e-inter-area-prefix:
  +--ro ospfv3-extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?         uint8
        +--ro af?                    iana-rt-types:address-family
        +--ro range-size?            uint16
        +--ro prefix?                inet:ip-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro ospfv3-prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro algorithm?                 identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?         uint32
        |        +--:(sid-index)
        |           +--ro index-value?         uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3
          /ospf:body/ospfv3-e-lsa:e-as-external:
  +--ro ospfv3-extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?         uint8
        +--ro af?                    iana-rt-types:address-family
        +--ro range-size?            uint16
        +--ro prefix?                inet:ip-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro ospfv3-prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro algorithm?                 identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?         uint32
        |        +--:(sid-index)
        |           +--ro index-value?         uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-nssa:
  +--ro ospfv3-extended-prefix-range-tlvs
     +--ro extended-prefix-range-tlv* []
        +--ro prefix-length?         uint8
        +--ro af?                    iana-rt-types:address-family
        +--ro range-size?            uint16
        +--ro prefix?                inet:ip-prefix
        +--ro prefix-sid-sub-tlvs
        |  +--ro prefix-sid-sub-tlv* []
        |     +--ro ospfv3-prefix-sid-flags
        |     |  +--ro flag*   identityref
        |     +--ro algorithm?                 identityref
        |     +--ro (sid)?
        |        +--:(sid-label)
        |        |  +--ro label-value?         uint32
        |        +--:(sid-index)
        |           +--ro index-value?         uint32
        +--ro unknown-tlvs
           +--ro unknown-tlv* []
              +--ro type?     uint16
              +--ro length?   uint16
              +--ro value?    yang:hex-string
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:interfaces/ospf:interface/ospf:database
          /ospf:link-scope-lsa-type/ospf:link-scope-lsas
          /ospf:link-scope-lsa/ospf:version/ospf:ospfv3
          /ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-link
          /ospfv3-e-lsa:e-link-tlvs/ospfv3-e-lsa:intra-prefix-tlv
          /ospfv3-e-lsa:sub-tlvs:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro ospfv3-prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro algorithm?                 identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?         uint32
           +--:(sid-index)
              +--ro index-value?         uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body
          /ospfv3-e-lsa:e-intra-area-prefix
          /ospfv3-e-lsa:e-intra-prefix-tlvs
          /ospfv3-e-lsa:intra-prefix-tlv/ospfv3-e-lsa:sub-tlvs:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro ospfv3-prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro algorithm?                 identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?         uint32
           +--:(sid-index)
              +--ro index-value?         uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body
          /ospfv3-e-lsa:e-inter-area-prefix
          /ospfv3-e-lsa:e-inter-prefix-tlvs
          /ospfv3-e-lsa:inter-prefix-tlv/ospfv3-e-lsa:sub-tlvs:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro ospfv3-prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro algorithm?                 identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?         uint32
           +--:(sid-index)
              +--ro index-value?         uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:database
          /ospf:as-scope-lsa-type/ospf:as-scope-lsas
          /ospf:as-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3
          /ospf:body/ospfv3-e-lsa:e-as-external
          /ospfv3-e-lsa:e-external-tlvs
          /ospfv3-e-lsa:external-prefix-tlv/ospfv3-e-lsa:sub-tlvs:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro ospfv3-prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro algorithm?                 identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?         uint32
           +--:(sid-index)
              +--ro index-value?         uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-nssa
          /ospfv3-e-lsa:e-external-tlvs
          /ospfv3-e-lsa:external-prefix-tlv/ospfv3-e-lsa:sub-tlvs:
  +--ro prefix-sid-sub-tlvs
     +--ro prefix-sid-sub-tlv* []
        +--ro ospfv3-prefix-sid-flags
        |  +--ro flag*   identityref
        +--ro algorithm?                 identityref
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?         uint32
           +--:(sid-index)
              +--ro index-value?         uint32
augment /rt:routing/rt:control-plane-protocols
          /rt:control-plane-protocol/ospf:ospf/ospf:areas
          /ospf:area/ospf:database/ospf:area-scope-lsa-type
          /ospf:area-scope-lsas/ospf:area-scope-lsa/ospf:version
          /ospf:ospfv3/ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-router
          /ospfv3-e-lsa:e-router-tlvs/ospfv3-e-lsa:link-tlv
          /ospfv3-e-lsa:sub-tlvs:
  +--ro adj-sid-sub-tlvs
  |  +--ro adj-sid-sub-tlv* []
  |     +--ro adj-sid-flags
  |     |  +--ro flag*   identityref
  |     +--ro weight?              uint8
  |     +--ro (sid)?
  |        +--:(sid-label)
  |        |  +--ro label-value?   uint32
  |        +--:(sid-index)
  |           +--ro index-value?   uint32
  +--ro lan-adj-sid-sub-tlvs
     +--ro lan-adj-sid-sub-tlv* []
        +--ro lan-adj-sid-flags
        |  +--ro flag*   identityref
        +--ro weight?               uint8
        +--ro neighbor-router-id?   rt-types:router-id
        +--ro (sid)?
           +--:(sid-label)
           |  +--ro label-value?    uint32
           +--:(sid-index)
              +--ro index-value?    uint32
]]></artwork>
]]></sourcecode>
    </section>
    <section anchor="Acknowledgements" numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t>
        The authors wish to thank <contact fullname="Dean Bogdanovic"/> and <contact fullname="Kiran Koushik Agrahara Sreenivasa"/>
        for their YANG module discussions.
      </t>
      <t>
        The authors wish to thank <contact fullname="Yi Yang"/>, <contact fullname="Alexander Clemm"/>,
        <contact fullname="Gaurav Gupta"/>, <contact fullname="Ladislav Lhotka"/>, <contact fullname="Stephane Litkowski"/>,
        <contact fullname="Greg Hankins"/>, <contact fullname="Manish Gupta"/>, <contact fullname="Alan Davey"/>, <contact fullname="Divakaran Baskaran"/>, <contact fullname="Reshad Rahman"/>, <contact fullname="Tom Petch"/>,
        and <contact fullname="Corey Bonnell"/> for their thorough reviews and helpful comments.
      </t>
      <t>
        The authors wish to thank <contact fullname="Julien Meuric"/> for a very meticulous Routing Directorate review.
      </t>
      <t>
        The authors wish to thank <contact fullname="Mohamed Boucadair"/> and <contact fullname="Ketan Talaulikar"/>
        for extensive AD reviews for the IESG Telechat. Thanks to <contact fullname="Éric Vyncke"/> and <contact fullname="Mahesh
        Jethanandani"/> for review comments.
      </t>
      <t>
        Author affiliation with The MITRE Corporation is provided for
        identification purposes only and is not intended to convey or imply MITRE's
        concurrence with, or support for, the positions, opinions, or viewpoints
        expressed.  MITRE has agreed to this document for Public Release,
        Distribution Unlimited, with Public Release Case Number 18-3281. This
        approval allows the MITRE employee to release contributions externally and
        does not assert authority to publish.
      </t>
    </section>
  </back>

<!--[rfced] Abbreviations

a) FYI - We have added expansions for the following abbreviations
per Section 3.6 of RFC 7322 ("RFC Style Guide"). Please review each
expansion in the document carefully to ensure correctness.

 IP Fast Reroute (IP-FRR)
 No Penultimate Hop-Popping) (No-PHP)
 Remote Loop-Free Alternate  (RLFA)
 Segment Routing Local Block (SRLB)

b) Both the expansion and the acronym for the following terms are used
throughout the document. Would you like to update to using the expansion
upon first usage and the acronym for the rest of the document for consistency?

 Adjacency Segment Identifier, adjacency Segment ID, adjacency SID (Adj-SID)
 Denial-of-Service (DoS)
 Remote LFA (RLFA)
 Segment ID, Segment Identifier (SID)
 Segment Routing Mapping Server, SR Mapping Server (SRMS)
 Segment Routing over MPLS (SR-MPLS)

c) FYI, we updated the expansion of "SRLG" from "Shared Resource Link
Group" to "Shared Risk Link Group" to match how it is expanded in
past RFCs.

d) FYI, we updated one instance of "SRBG" to "SRGB" (Section 4) to
match usage in the rest of the document.
-->

<!-- [rfced] Terminology

a) Throughout the text, the following terminology appears to be used
inconsistently. Please review these occurrences and let us know if/how they
may be made consistent.

 Segment Routing vs. segment routing

b) For consistency and to reflect how they appear in previously published
RFCs, we have updated the terminology to the form on the right. Please review
and let us know if any further updates are needed.

 Adj-SID sub-TLV, Adj-SID sub-tlv, Adj-sid sub-tlv > Adj-SID Sub-TLV

 Prefix SID Sub-TLV, prefix SID sub-TLV, Prefix SID sub-TLV > Prefix-SID Sub-TLV
-->

<!-- [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.
-->

</rfc>