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A YANG Data Model for OSPF Segment Routing for the MPLS Data Plane
draft-ietf-ospf-sr-yang-35

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9903.
Authors Yingzhen Qu , Acee Lindem , Zhaohui (Jeffrey) Zhang , Ing-Wher (Helen) Chen
Last updated 2025-03-28 (Latest revision 2025-02-07)
RFC stream Internet Engineering Task Force (IETF)
Formats
Reviews
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Associated WG milestone
Jan 2025
OSPF Segment Routing YANG Model
Document shepherd Christian Hopps
Shepherd write-up Show Last changed 2025-01-15
IESG IESG state Became RFC 9903 (Proposed Standard)
Consensus boilerplate Yes
Telechat date (None)
Has enough positions to pass.
Responsible AD Gunter Van de Velde
Send notices to Christian Hopps <chopps@chopps.org>
IANA IANA review state Version Changed - Review Needed
IANA expert review state Expert Reviews OK
draft-ietf-ospf-sr-yang-35
Internet                                                           Y. Qu
Internet-Draft                                    Futurewei Technologies
Intended status: Standards Track                               A. Lindem
Expires: 29 September 2025                       LabN Consulting, L.L.C.
                                                                J. Zhang
                                                        Juniper Networks
                                                                 I. Chen
                                                   The MITRE Corporation
                                                           28 March 2025

   A YANG Data Model for OSPF Segment Routing for the MPLS Data Plane
                       draft-ietf-ospf-sr-yang-35

Abstract

   This document defines a YANG data module that can be used to
   configure and manage OSPF Extensions for Segment Routing for the MPLS
   data plane.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 29 September 2025.

Copyright Notice

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

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
     1.2.  YANG Data Module Scope  . . . . . . . . . . . . . . . . .   3
     1.3.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
   2.  OSPF Segment Routing  . . . . . . . . . . . . . . . . . . . .   4
     2.1.  OSPF Segment Routing YANG Module  . . . . . . . . . . . .  15
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  41
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  42
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  43
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  43
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  43
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  46
   Appendix A.  A Configuration Example  . . . . . . . . . . . . . .  47
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  49

1.  Overview

   This document defines a YANG data model [RFC7950] that can be used to
   configure and manage OSPFv2 extensions for Segment Routing [RFC8665]
   and OSPFv3 extensions for Segment Routing [RFC8666] for the MPLS data
   plane.  It is an augmentation to the OSPF YANG data model [RFC9129].

   The YANG module in this document conforms to the Network Management
   Datastore Architecture (NMDA) [RFC8342].

1.1.  Requirements Language

   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 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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1.2.  YANG Data Module Scope

   The ietf-ospf-sr-mpls data module defines both the data nodes to
   configure OSPF segment routing MPLS extensions and the additions to
   the OSPF Link State Advertisements (LSAs) necessary to support MPLS
   segment routing.  The OSPF configuration includes:

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

   *  OSPF interface level configuration for adjacency 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 data module (refer to the igp-protocol
      grouping [RFC9020]).

   *  OSPF interface level configuration for Topology-Independent Loop-
      Free Alternative (TI-LFA) using the MPLS data plane.  TI-LFA is
      described in [I-D.ietf-rtgwg-segment-routing-ti-lfa].

   The operational state (read-only) additions to specifc to OSPFv2 LSA
   include:

   *  OSPFv2 extended range TLV encodings [RFC8665] in the OSPF
      Extended-Prefix Opaque LSA [RFC7684].

   *  OSPFv2 Prefix SID Sub-TLV encodings [RFC8665] included the OSPF
      Extended Prefix TLV which is advertised in the OSPF Extended
      Prefix Opaque LSA [RFC7684].

   *  OSPFv2 Prefix SID Sub-TLV encodings [RFC8665] included the OSPF
      Extended Prefix TLV which is advertised in the OSPF Extended
      Prefix Opaque LSA [RFC7684].

   *  OSPFv2 SR-Algorithm, SID/Label Range TLVs, SR Local Block TLVs,
      Segment Routing Mapping Server (SRMS) preference TLV [RFC8665]
      advertised in the OSPFv2 Router Information Opaque LSA [RFC7770].

   The operational state (read-only) additions to specifc to OSPFv3 LSA
   include:

   *  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].

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   *  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 Prefix-SID Sub-TLV encodings [RFC8666] in the OSPFv3 Intra-
      Area Prefix TLV, Inter-Area Prefix TLV, External Prefix TLV, and
      OSPFv3 Extended Prefix Range TLV [RFC8362].

   *  OSPFv3 Adj-SID Sub-TLV in the OSPFv3 Router-Link TLV [RFC8362].

   *  OSPFv3 Adj-SID Sub-TLV in the OSPFv3 Router-Link TLV [RFC8362].

   *  OSPFv3 Lan Adj-SID Sub-TLV in the OSPFv3 Router-Link TLV
      [RFC8362].

   *  OSPFv3 SR-Algorithm, SID/Label Range TLVs, SR Local Block TLVs,
      Segment Routing Mapping Server (SRMS) preference TLV [RFC8666]
      advertised in the OSPFv3 Router Information LSA [RFC7770].

1.3.  Tree Diagrams

   This document uses the graphical representation of data models
   defined in [RFC8340].

2.  OSPF Segment Routing

   This document defines a model for OSPF Segment Routing Extensions for
   both OSPFv2 [RFC8665] and OSPFv3 [RFC8666].  It is an augmentation of
   the OSPF base model.

   The OSPF SR YANG module requires support for the base segment routing
   module [RFC9020], which defines the global segment routing
   configuration independent of any specific routing protocol
   configuration, and support of OSPF base model [RFC9129] which defines
   basic OSPF configuration and state.

   module: ietf-ospf-sr-mpls
   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

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           +--rw upper-bound    uint32
   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: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 flags*   identityref
           +--ro prefix?                        inet:ipv4-prefix
           +--ro prefix-sid-sub-tlvs
           |  +--ro prefix-sid-sub-tlv* []

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           |     +--ro prefix-sid-flags
           |     |  +--ro flags*   identityref
           |     +--ro mt-id?              uint8
           |     +--ro algorithm?          identityref
           |     +--ro sid?                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 flags*   identityref
           +--ro prefix?                        inet:ipv4-prefix
           +--ro prefix-sid-sub-tlvs
           |  +--ro prefix-sid-sub-tlv* []
           |     +--ro prefix-sid-flags
           |     |  +--ro flags*   identityref
           |     +--ro mt-id?              uint8
           |     +--ro algorithm?          identityref
           |     +--ro sid?                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 flags*   identityref
           +--ro mt-id?              uint8
           +--ro algorithm?          identityref

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           +--ro sid?                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 flags*   identityref
           +--ro mt-id?              uint8
           +--ro algorithm?          identityref
           +--ro sid?                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 flags*   identityref
     |     +--ro mt-id?           uint8
     |     +--ro weight?          uint8
     |     +--ro sid?             uint32
     +--ro lan-adj-sid-sub-tlvs
        +--ro lan-adj-sid-sub-tlv* []
           +--ro lan-adj-sid-flags
           |  +--ro flags*   identityref
           +--ro mt-id?                uint8
           +--ro weight?               uint8
           +--ro neighbor-router-id?   rt-types:router-id
           +--ro sid?                  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-sub-tlv
     |        +--ro length?               uint16

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     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-value?   uint32
     +--ro local-block-tlvs
     |  +--ro local-block-tlv* []
     |     +--ro range-size?    rt-types:uint24
     |     +--ro sid-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-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-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-value?   uint32
     +--ro local-block-tlvs
     |  +--ro local-block-tlv* []
     |     +--ro range-size?    rt-types:uint24
     |     +--ro sid-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-value?   uint32

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     +--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-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-value?   uint32
     +--ro local-block-tlvs
     |  +--ro local-block-tlv* []
     |     +--ro range-size?    rt-types:uint24
     |     +--ro sid-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-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-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?

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     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-value?   uint32
     +--ro local-block-tlvs
     |  +--ro local-block-tlv* []
     |     +--ro range-size?    rt-types:uint24
     |     +--ro sid-sub-tlv
     |        +--ro length?               uint16
     |        +--ro sid-raw?              uint32
     |        +--ro (sid-value)?
     |           +--:(label-sid)
     |           |  +--ro label-value?    uint32
     |           +--:(offset-sid)
     |              +--ro offset-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 flags*   identityref
           |     +--ro algorithm?                 identityref
           |     +--ro sid-raw?                   uint32
           |     +--ro (sid-value)?
           |        +--:(label-sid)
           |        |  +--ro label-value?         uint32
           |        +--:(offset-sid)
           |           +--ro offset-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

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             /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 flags*   identityref
           |     +--ro algorithm?                 identityref
           |     +--ro sid-raw?                   uint32
           |     +--ro (sid-value)?
           |        +--:(label-sid)
           |        |  +--ro label-value?         uint32
           |        +--:(offset-sid)
           |           +--ro offset-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 flags*   identityref
           |     +--ro algorithm?                 identityref
           |     +--ro sid-raw?                   uint32
           |     +--ro (sid-value)?
           |        +--:(label-sid)
           |        |  +--ro label-value?         uint32
           |        +--:(offset-sid)
           |           +--ro offset-value?        uint32
           +--ro unknown-tlvs

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              +--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 flags*   identityref
           |     +--ro algorithm?                 identityref
           |     +--ro sid-raw?                   uint32
           |     +--ro (sid-value)?
           |        +--:(label-sid)
           |        |  +--ro label-value?         uint32
           |        +--:(offset-sid)
           |           +--ro offset-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 flags*   identityref
           +--ro algorithm?                 identityref
           +--ro sid-raw?                   uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?         uint32
              +--:(offset-sid)

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                 +--ro offset-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 flags*   identityref
           +--ro algorithm?                 identityref
           +--ro sid-raw?                   uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?         uint32
              +--:(offset-sid)
                 +--ro offset-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 flags*   identityref
           +--ro algorithm?                 identityref
           +--ro sid-raw?                   uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?         uint32
              +--:(offset-sid)
                 +--ro offset-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* []

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           +--ro ospfv3-prefix-sid-flags
           |  +--ro flags*   identityref
           +--ro algorithm?                 identityref
           +--ro sid-raw?                   uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?         uint32
              +--:(offset-sid)
                 +--ro offset-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 flags*   identityref
           +--ro algorithm?                 identityref
           +--ro sid-raw?                   uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?         uint32
              +--:(offset-sid)
                 +--ro offset-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 flags*   identityref
     |     +--ro weight?               uint8
     |     +--ro sid-raw?              uint32
     |     +--ro (sid-value)?
     |        +--:(label-sid)
     |        |  +--ro label-value?    uint32
     |        +--:(offset-sid)
     |           +--ro offset-value?   uint32
     +--ro lan-adj-sid-sub-tlvs
        +--ro lan-adj-sid-sub-tlv* []
           +--ro lan-adj-sid-flags

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           |  +--ro flags*   identityref
           +--ro weight?               uint8
           +--ro neighbor-router-id?   rt-types:router-id
           +--ro sid-raw?              uint32
           +--ro (sid-value)?
              +--:(label-sid)
              |  +--ro label-value?    uint32
              +--:(offset-sid)
                 +--ro offset-value?   uint32

2.1.  OSPF Segment Routing YANG Module

   [RFC2328], [RFC4750], [RFC4915], [RFC5340], [RFC5643], [RFC5838],
   [RFC6991], [RFC8102], [RFC8294], [RFC8343], [RFC8476], [RFC8349],
   [RFC9587], and [I-D.ietf-rtgwg-segment-routing-ti-lfa] are referenced
   in the YANG data model.

   <CODE BEGINS> file "ietf-ospf-sr-mpls@2025-03-27.yang"
   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";

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     }
     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), which
        is common across all of the vendor implementations. It is
        intended that the module will be extended by vendors to
        define vendor-specific OSPF Segment Routing configuration
        and operational parameters for the MPLS data plane.

        This YANG model conforms to the Network Management
        Datastore Architecture (NMDA) as described in RFC 8342.

        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

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

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

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

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

     revision 2025-03-28 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for OSPF Segment Routing for
          the MPLS Data Plane";
     }

     feature remote-lfa-sr {
       description
         "Enhance rLFA to use SR path.";
       reference
         "RFC 8102: Remote-LFA Node Protection and Manageability";
     }

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

     identity prefix-sid-flag {
       description

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         "Base identity for prefix SID sub-TLV flags.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing
          RFC 8666: OSPFv3 Extensions for Segment Routing";
     }

     identity np-flag {
       base prefix-sid-flag;
       description
         "No-PHP flag.";
     }

     identity m-flag {
       base prefix-sid-flag;
       description
         "Mapping server flag.";
     }

     identity e-flag {
       base prefix-sid-flag;
       description
         "Explicit-NULL flag.";
     }

     identity v-flag {
       base prefix-sid-flag;
       description
         "Value/Index flag.";
     }

     identity l-flag {
       base prefix-sid-flag;
       description
         "Local flag.";
     }

     identity extended-prefix-range-flag {
       description
         "Base identity for extended prefix range TLV flags.";
     }

     identity ia-flag {
       base extended-prefix-range-flag;
       description
         "Inter-Area flag. If set, advertisement is of
          inter-area type.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing";

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     }

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

     identity b-flag {
       base adj-sid-flag;
       description
         "Backup flag.";
     }

     identity vi-flag {
       base adj-sid-flag;
       description
         "Value/Index flag.";
     }

     identity lo-flag {
       base adj-sid-flag;
       description
         "Local/Global flag.";
     }

     identity g-flag {
       base adj-sid-flag;
       description
         "Group flag.";
     }

     identity p-flag {
       base adj-sid-flag;
       description
         "Persistent flag.";
     }

     /* Groupings */
     grouping sid-tlv-encoding {
       leaf sid-raw {
         type uint32;
         description
           "Raw SID value - labels are in the rightmost 20 bits of
           the value";
       }

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       choice sid-value {
         case label-sid {
           leaf label-value {
             type uint32 {
                 range "0 .. 1048575";
             }
             description
               "A 20-bit MPLS Label";
           }
         }
         case offset-sid {
           leaf offset-value {
             type uint32;
             description
               "Offset into a label space advertised by this router.";
           }
         }
         description
           "Choice of either a 20-bit MPLS lable or 32-bit offset into
            an advertised label space.";
       }
       description
         "SID TLV Encoding -  20-bit label or 32-bit SID 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 V-Flag is set to 1 and L-Flag is set to 1: The
           ID/Index/Label field is a 3-octet local label where the
           20 rightmost bits are used for encoding the label value.";
     }

     grouping sid-sub-tlv {
       description
         "SID/Label sub-TLV grouping.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing
          (Section 6)";
       container sid-sub-tlv {
         description
           "Used to advertise the SID/Label associated with a
            prefix or adjacency.";

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         leaf length {
           type uint16;
           description
             "Length of the SID value. YANG model specification
              is necessary since it dictates the semantics of the
              SID.";
         }
         uses sid-tlv-encoding;
       }
     }

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

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           }
           leaf sid {
             type uint32;
             description
               "Segment Identifier (SID) - A 20 bit label or
                an index into the SID/Label space.

                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 V-Flag is set to 1 and L-Flag is set to 1: The
                SID/Index/Label field is a 3-octet local label where
                the 20 rightmost bits are used for encoding the label
                value.";
           }
         }
       }
     }

     grouping ospfv2-extended-prefix-range-tlvs {
       description
         "Extended prefix range TLV grouping.";
       reference
         "RFC 8665: OSPF Extensions for Segment 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.";

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           }
           container extended-prefix-range-flags {
             leaf-list flags {
               type identityref {
                 base extended-prefix-range-flag;
               }
               description
                 "Extended 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 sr-algorithm-tlv {
       description
         "SR algorithm TLV grouping.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing
          (Section 3.1)";
       container sr-algorithm-tlv {
         description
           "All 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

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          (Section 3.2)";
       container sid-range-tlvs {
         description
           "List of SID range TLVs. Note that the order of advertised
            SID ranges is implementation dependent.";
         list sid-range-tlv {
           description
             "SID range TLV.";
           leaf range-size {
             type rt-types:uint24;
             description
               "SID range.";
           }
           uses sid-sub-tlv;
         }
       }
     }

     grouping local-block-tlvs {
       description
         "The SR local block TLV contains the
          range of labels reserved for local SIDs.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing
          (Section 3.3)";
       container local-block-tlvs {
         description
           "List of 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-sub-tlv;
         }
       }
     }

     grouping srms-preference-tlv {
       description
         "The SR Mapping Server (SRMS) 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

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          preference value are preferred over those with
          a lower preference value.";
       reference
         "RFC 8665: OSPF Extensions for Segment Routing
          (Section 3.4)";
       container srms-preference-tlv {
         description
           "SRMS Preference TLV.";
         leaf preference {
           type uint8;
           description
             "SRMS preference TLV, value from 0 to 255 with
              255 being the most preferred.";
         }
       }
     }

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

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         }
       }
     }

     grouping ospfv3-extended-prefix-range-tlvs {
       description
         "Extended prefix range TLV grouping.";
       reference
         "RFC 8666: OSPFv3 Extensions for Segment Routing
          (Section 5)";
       container ospfv3-extended-prefix-range-tlvs {
         description
           "List of 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
         "Adj-SID sub-TLV grouping.";
       reference
         "RFC 8666: OSPFv3 Extensions for Segment Routing

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          (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.";
           container adj-sid-flags {
             leaf-list flags {
               type identityref {
                 base adj-sid-flag;
               }
               description
                 "Adj-SID sub-tlv flags.";
             }
             description
               "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
         "LAN Adj-SID sub-TLV grouping.";
       reference
         "RFC 8666: OSPFv3 Extensions for Segment 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.";
           container lan-adj-sid-flags {
             leaf-list flags {
               type identityref {
                 base adj-sid-flag;
               }
               description
                 "LAN Adj-SID sub-TLV flags.";
             }

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             description
               "LAN Adj-SID 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 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 for the MPLS data plane. The following semantic
          validation be performed for the configuration data:
           - Assure the binding policies prefixes do not overlapp.";
       uses sr-mpls:sr-control-plane;
       container protocol-srgb {
         if-feature "sr-mpls:protocol-srgb";
         uses sr-cmn:srgb;
         description
           "Per-protocol SRGB.";
       }
       reference
         "RFC 9020 - YANG Data Model for Segment Routing";
   }

     augment "/rt:routing/rt:control-plane-protocols/"
           + "rt:control-plane-protocol/ospf:ospf/"
           + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface" {

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       when "derived-from(/rt:routing/rt:control-plane-protocols/"
          + "rt:control-plane-protocol/rt:type, 'ospf:ospf')" {
         description
           "This augments the OSPF interface configuration
            when used.";
       }
       description
         "This augments the OSPF protocol interface
          configuration with 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 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.";
           }
         }
       }
       reference
         "RFC 9020 - YANG Data Model for Segment Routing";
     }

     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 with TI-LFA.";
       container ti-lfa {
         if-feature "ti-lfa";
         leaf enabled {
           type boolean;

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           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.";
             }
             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";
             leaf priority {
               type uint8;
               default "128";
               description
                 "Priority for SRLG disjoint tie-breaker with
                  a lower priority being more preferred.";
             }
             description
               "Enable SRLG (Sharsed Resource Link Group)
                disjoint as a TI-LFA path selection tie-breaker.
                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.";
           }
           description
             "Configure path selection tie-breakers and their
              respective priorities for the TI-LFA computation.
              multiple tie-breakers and priorities configured may
              be configured.";
         }
         description
           "Topology-Independent Loop Free Alternate
            (TI-LFA) support.";
         reference

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           "draft-ietf-rtgwg-segment-routing-ti-lfa -
            Topology-Independent Fast Reroute using Segment Routing";
       }
     }

     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 LFA.";
       leaf use-segment-routing-path {
         if-feature "remote-lfa-sr";
         type boolean;
         default "false";
         description
           "Force remote LFA to use segment routing path instead of LDP
            path. The value of this leaf is in effect only when
            remote-lfa is enabled.";
       }
     }

     /*
      * 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

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         "SR Extended Prefix Range TLV in OSPFv2 Type 10 (area-scoped)
          Extended Prefix Opaque LSAs.";
       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.";
       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 for OSPFv2 Extended Prefix TLVs
         in OSPFv2 Type 10 (area-scoped) Extended Prefix Opaque LSAs.";
       uses ospfv2-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:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/"

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           + "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 for OSPFv2 Extended Prefix TLVs
         in OSPFv2 Type 11 (AS-scoped) Extended Prefix Opaque LSAs.";
      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.";
       container adj-sid-sub-tlvs {
         description
           "Adj-SID optional sub-TLVs.";
         list adj-sid-sub-tlv {
           description
             "List of Adj-SID sub-TLVs.";
           container adj-sid-flags {
             leaf-list flags {
               type identityref {
                 base adj-sid-flag;
               }
               description
                 "Adj-SID sub-TLV flags.";
             }
             description
               "Adj-SID sub-TLV flags.";
           }
           leaf mt-id {
             type uint8;
             description

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               "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 sid {
             type uint32;
             description
               "Segment Identifier (SID) - A 20 bit label or
                an index into the SID/Label space.

                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 V-Flag is set to 1 and L-Flag is set to 1: The
                SID/Index/Label field is a 3-octet local label where
                the 20 rightmost bits are used for encoding the label
                value.";
           }
         }
       }
       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.";
           container lan-adj-sid-flags {
             leaf-list flags {
               type identityref {
                 base adj-sid-flag;
               }
               description
                 "LAN Adj-SID sub-TLV flags.";
             }
             description
               "LAN Adj-SID sub-TLV flags.";
           }
           leaf mt-id {
             type uint8;
             description

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               "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.";
           }
           leaf sid {
             type uint32;
             description
               "Segment Identifier (SID) - A 20 bit label or
                an index into the SID/Label space.

                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 V-Flag is set to 1 and L-Flag is set to 1: The
                SID/Index/Label field is a 3-octet local label where
                the 20 rightmost bits are used for encoding the label
                value.";
           }
         }
       }
     }

     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

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         "SR TLVs for OSPFv2 Router Information Type 10 (area-scoped)
         Opaque LSAs";
       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";
       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).";
       uses sr-algorithm-tlv;
       uses sid-range-tlvs;
       uses local-block-tlvs;
       uses srms-preference-tlv;
     }

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     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).";
       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.";

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       }
       uses ospfv3-extended-prefix-range-tlvs;
       description
         "SR Extended Prefix Range TLVs in OSPFv3
         E-Inter-Area-Prefix 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/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.";
       }
       uses ospfv3-extended-prefix-range-tlvs;
       description
         "SR Extended Prefix Range TLVs in OSPFv3 E-AS-External 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-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.";
       }
       uses ospfv3-extended-prefix-range-tlvs;
       description
         "SR Extended Prefix Range TLVs in OSPFv3 E-NSSA LSAs.";
     }

     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/"

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           + "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.";
       }
       uses ospfv3-prefix-sid-sub-tlvs;
       description
         "SR Prefix-SID Sub-TLV in OSPFv3 Intra-Area
         Prefix TLV for OSPFv3 E-Link 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-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";
       }
       uses ospfv3-prefix-sid-sub-tlvs;
       description
         "SR Prefix-SID Sub-TLV in OSPFv3 Intra-Area
          Prefix TLV for 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/"
           + "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.";
       }
       uses ospfv3-prefix-sid-sub-tlvs;

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       description
         "SR Prefix-SID Sub-TLV in OSPFv3 Link-Scoped Intra-Area
          Prefix TLV for OSPFv3 E-Inter-Area-Prefix 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/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.";
       }
       uses ospfv3-prefix-sid-sub-tlvs;
       description
         "SR Prefix-SID Sub-TLV in OSPFv3 External Prefix TLV
          for OSPFv3 E-AS-External 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-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.";
       }
       uses ospfv3-prefix-sid-sub-tlvs;
       description
         "SR Prefix-SID Sub-TLV in OSPFv3 External Prefix TLV
          for OSPFv3 E-NSSA LSAs.";
     }

     augment "/rt:routing/"
           + "rt:control-plane-protocols/rt:control-plane-protocol/"
           + "ospf:ospf/ospf:areas/ospf:area/ospf:database/"

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           + "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";
       }
       uses ospfv3-adj-sid-sub-tlvs;
       uses ospfv3-lan-adj-sid-sub-tlvs;
       description
         "SR Sub-TLVs in OSPFv3 link-tlv for OSPFv3 E-Router LSAs";
     }
   }
   <CODE ENDS>

                                  Figure 1

3.  Security Considerations

   The YANG module specified in this document define a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The NETCONF Configuration Access Control model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a pre-configured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are a number of data nodes defined in the module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      /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.

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      /ospf:ospf/segment-routing/bindings - Modification to the local
      bindings could result in a Denial-of-Service (DoS) attack.

      /ospf:ospf/protocol-srgb - Modification of the protocol SRGB could
      be used to mount a DoS attack.  For example, if the protocol SRBG
      size is reduced to a very small value, a lot of existing segments
      could no longer be installed leading to a traffic disruption.

      /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.

      /ospf:interfaces/ospf:interface/ospf:fast-reroute/ti-lfa -
      Modification of the TI-LFA enablement could lead to traffic
      disruption.

   Some of the readable data nodes in the 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.

   The module ietf-ospf-sr-mpls augments base OSPF module data base with
   various TLVs.  Knowledge of these data nodes can be used to attack
   other routers in the OSPF domain.

4.  Acknowledgements

   The authors wish to thank Dean Bogdanovic and Kiran Koushik Agrahara
   Sreenivasa for their YANG model discussions.

   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.

   The authors wish to thank Julien Meuric for a very meticulous Routing
   Directorate review.

   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 approved this document for Public
   Release, Distribution Unlimited, with Public Release Case Number
   18-3281.

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5.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registration is
   requested to be made:

         URI: urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls
         Registrant Contact: The IESG.
         XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

         name: ietf-ospf-sr-mpls
         namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-sr-mpls
         prefix: ospf-sr-mpls
         reference: RFC XXXX

6.  References

6.1.  Normative References

   [I-D.ietf-rtgwg-segment-routing-ti-lfa]
              Bashandy, A., Litkowski, S., Filsfils, C., Francois, P.,
              Decraene, B., and D. Voyer, "Topology Independent Fast
              Reroute using Segment Routing", Work in Progress,
              Internet-Draft, draft-ietf-rtgwg-segment-routing-ti-lfa-
              21, 12 February 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-rtgwg-
              segment-routing-ti-lfa-21>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC4750]  Joyal, D., Ed., Galecki, P., Ed., and S. Giacalone, Ed.,
              "OSPF Version 2 Management Information Base", RFC 4750,
              DOI 10.17487/RFC4750, December 2006,
              <https://www.rfc-editor.org/info/rfc4750>.

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   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <https://www.rfc-editor.org/info/rfc4915>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <https://www.rfc-editor.org/info/rfc5340>.

   [RFC5643]  Joyal, D., Ed. and V. Manral, Ed., "Management Information
              Base for OSPFv3", RFC 5643, DOI 10.17487/RFC5643, August
              2009, <https://www.rfc-editor.org/info/rfc5643>.

   [RFC5838]  Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and
              R. Aggarwal, "Support of Address Families in OSPFv3",
              RFC 5838, DOI 10.17487/RFC5838, April 2010,
              <https://www.rfc-editor.org/info/rfc5838>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7684]  Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
              Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
              Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
              2015, <https://www.rfc-editor.org/info/rfc7684>.

   [RFC7770]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
              February 2016, <https://www.rfc-editor.org/info/rfc7770>.

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   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8102]  Sarkar, P., Ed., Hegde, S., Bowers, C., Gredler, H., and
              S. Litkowski, "Remote-LFA Node Protection and
              Manageability", RFC 8102, DOI 10.17487/RFC8102, March
              2017, <https://www.rfc-editor.org/info/rfc8102>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8294]  Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger,
              "Common YANG Data Types for the Routing Area", RFC 8294,
              DOI 10.17487/RFC8294, December 2017,
              <https://www.rfc-editor.org/info/rfc8294>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/info/rfc8343>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8362]  Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
              F. Baker, "OSPFv3 Link State Advertisement (LSA)
              Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
              2018, <https://www.rfc-editor.org/info/rfc8362>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

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   [RFC8476]  Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
              "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
              DOI 10.17487/RFC8476, December 2018,
              <https://www.rfc-editor.org/info/rfc8476>.

   [RFC8665]  Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
              H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
              Extensions for Segment Routing", RFC 8665,
              DOI 10.17487/RFC8665, December 2019,
              <https://www.rfc-editor.org/info/rfc8665>.

   [RFC8666]  Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
              for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
              December 2019, <https://www.rfc-editor.org/info/rfc8666>.

   [RFC9020]  Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J.
              Tantsura, "YANG Data Model for Segment Routing", RFC 9020,
              DOI 10.17487/RFC9020, May 2021,
              <https://www.rfc-editor.org/info/rfc9020>.

   [RFC9129]  Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
              "YANG Data Model for the OSPF Protocol", RFC 9129,
              DOI 10.17487/RFC9129, October 2022,
              <https://www.rfc-editor.org/info/rfc9129>.

   [RFC9587]  Lindem, A., Palani, S., and Y. Qu, "YANG Data Model for
              OSPFv3 Extended Link State Advertisements (LSAs)",
              RFC 9587, DOI 10.17487/RFC9587, June 2024,
              <https://www.rfc-editor.org/info/rfc9587>.

6.2.  Informative References

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8792]  Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
              "Handling Long Lines in Content of Internet-Drafts and
              RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
              <https://www.rfc-editor.org/info/rfc8792>.

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Appendix A.  A Configuration Example

   The following is an XML example using the OSPF SR YANG module, and
   RFC 9020.

   Note: '\' line wrapping per [RFC8792].

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   <?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>
                 <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>

   The following is the same example using JSON format.

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   {
     "routing": {
       "router-id": "1.1.1.1",
       "control-plane-protocols": {
         "control-plane-protocol": {
           "type": "ospf:ospfv2",
           "name": "OSPFv2",
           "ospf": {
             "areas": {
               "area": {
                 "area-id": "0.0.0.0",
                 "interfaces": {
                   "interface": {
                     "name": "eth0",
                     "segment-routing": {
                       "adjacency-sid": {
                         "adj-sids": {
                           "value": 3888
                         }
                       }
                     }
                   }
                 }
               }
             },
             "segment-routing": {
               "enabled": true
             },
             "protocol-srgb": {
               "srgb": {
                 "lower-bound": 4000,
                 "upper-bound": 5000
               }
             }
           }
         }
       }
     }
   }

Authors' Addresses

   Yingzhen Qu
   Futurewei Technologies
   2330 Central Expressway
   Santa Clara, CA 95050
   United States of America
   Email: yingzhen.ietf@gmail.com

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   Acee Lindem
   LabN Consulting, L.L.C.
   301 Midenhall Way
   Cary, NC 27513
   Email: acee.ietf@gmail.com

   Jeffrey Zhang
   Juniper Networks
   10 Technology Park Drive
   Westford, MA 01886
   United States of America
   Email: zzhang@juniper.net

   Ing-Wher Chen
   The MITRE Corporation
   Email: ingwherchen@mitre.org

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