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YANG Data Model for OSPF Segment Routing
draft-ietf-ospf-sr-yang-17

Document Type Active Internet-Draft (lsr WG)
Authors Derek M. Yeung , Yingzhen Qu , Zhaohui (Jeffrey) Zhang , Ing-Wher Chen , Acee Lindem
Last updated 2022-01-02
Stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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draft-ietf-ospf-sr-yang-17
Internet                                                        D. Yeung
Internet-Draft                                                    Arrcus
Intended status: Standards Track                                   Y. Qu
Expires: 6 July 2022                                           Futurewei
                                                                J. Zhang
                                                        Juniper Networks
                                                                 I. Chen
                                                   The MITRE Corporation
                                                               A. Lindem
                                                           Cisco Systems
                                                          2 January 2022

                YANG Data Model for OSPF Segment Routing
                       draft-ietf-ospf-sr-yang-17

Abstract

   This document defines a YANG data module that can be used to
   configure and manage OSPF Extensions for Segment Routing.  It also
   defines a module for management of Signaling Maximum SID Depth (MSD)
   Using OSPF.

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 6 July 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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.

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   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 . . . . . . . . . . . . . . . . . .   3
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   3
   2.  OSPF MSD  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  OSPF MSD YANG Module  . . . . . . . . . . . . . . . . . .   4
   3.  OSPF Segment Routing  . . . . . . . . . . . . . . . . . . . .  11
     3.1.  OSPF Segment Routing YANG Module  . . . . . . . . . . . .  16
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  31
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  31
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  32
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  34
   Appendix A.  Contributors' Addreses . . . . . . . . . . . . . . .  34
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  34

1.  Overview

   YANG [RFC7950] is a data definition language used to define the
   contents of a conceptual data store that allows networked devices to
   be managed using NETCONF [RFC6241].  YANG is proving relevant beyond
   its initial confines, as bindings to other interfaces (e.g., ReST)
   and encodings other than XML (e.g., JSON) are being defined.
   Furthermore, YANG data models can be used as the basis for
   implementation of other interfaces, such as CLI and programmatic
   APIs.

   This document defines a YANG data model that can be used to configure
   and manage OSPFv2 extensions for Segment Routing [RFC8665] and it is
   an augmentation to the OSPF YANG data model.

   This document also defines a YANG data model for Signaling Maximum
   SID Depth (MSD) Using OSPF [RFC8476], which augments the base OSPF
   YANG data model.

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

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1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

1.2.  Tree Diagrams

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

2.  OSPF MSD

   This document defines a model for Signaling Maximum SID Depth (MSD)
   Using OSPF [RFC8476].  It is an augmentation of the OSPF base model.

  module: ietf-ospf-msd
    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 node-msd-tlv
         +--ro node-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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 node-msd-tlv
         +--ro node-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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 node-msd-tlv
         +--ro node-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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

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            /ospf:router-information:
      +--ro node-msd-tlv
         +--ro node-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   uint8
    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:ospfv2/ospf:ospfv2
            /ospf:body/ospf:opaque/ospf:extended-link-opaque
            /ospf:extended-link-tlv:
      +--ro link-msd-sub-tlv
         +--ro link-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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:ospfv2/ospf:ospfv2
            /ospf:body/ospf:opaque/ospf:extended-link-opaque
            /ospf:extended-link-tlv:
      +--ro link-msd-sub-tlv
         +--ro link-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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:extended-link-opaque/ospf:extended-link-tlv:
      +--ro link-msd-sub-tlv
         +--ro link-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   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-router/ospfv3-e-lsa:e-router-tlvs:
      +--ro link-msd-sub-tlv
         +--ro link-msds* [msd-type]
            +--ro msd-type     identityref
            +--ro msd-value?   uint8

2.1.  OSPF MSD YANG Module

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   <CODE BEGINS> file "ietf-ospf-msd@2022-01-02.yang"
   module ietf-ospf-msd {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-msd";
     prefix ospf-msd;

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

     import ietf-ospf {
       prefix ospf;
     }

     import ietf-ospfv3-extended-lsa {
       prefix ospfv3-e-lsa;
     }

     organization
       "IETF LSR - LSR Working Group";
     contact
       "WG Web:   <https://tools.ietf.org/wg/mpls/>
        WG List:  <mailto:mpls@ietf.org>

        Author:    Yingzhen Qu
                  <mailto:yingzhen.qu@futurewei.com>
        Author:    Acee Lindem
                  <mailto:acee@cisco.com>
        Author:    Stephane Litkowski
                  <mailto:slitkows.ietf@gmail.com>
        Author:    Jeff Tantsura
                  <jefftant.ietf@gmail.com>

       ";
     description
       "The YANG module augments the base OSPF model to
        manage different types of MSDs.

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

        Copyright (c) 2022 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to

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        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;
        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.";

     reference "RFC XXXX: YANG Data Model for OSPF MSD.";

     revision 2022-01-02 {
       description
         "Initial Version";
       reference "RFC XXXX: YANG Data Model for OSPF MSD.";
     }

     identity msd-base-type {
       description
         "Base identity for MSD Type";
     }

     identity base-mpls-msd {
       base msd-base-type;
       description
         "Base MPLS Imposition MSD.";
       reference
         "RFC 8491: Singling MSD using IS-IS.";
     }

     identity erld-msd {
       base msd-base-type;
       description
         "ERLD-MSD is defined to advertise the ERLD.";
       reference
         "RFC 8662: Entropy Label for Source Packet Routing in
                    Networking (SPRING) Tunnels";
     }

     grouping node-msd-tlv {
       description
         "Grouping for node MSD.";

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       container node-msd-tlv {
         list node-msds {
           key "msd-type";
           leaf msd-type {
             type identityref {
             base msd-base-type;
             }
             description
               "MSD-Types";
           }
           leaf msd-value {
             type uint8;
             description
               "MSD value, in the range of 0-255.";
           }
           description
             "Node MSD is the smallest link MSD supported by
              the node.";
         }
         description
           "Node MSD is the number of SIDs supported by a node.";
         reference
           "RFC 8476: Signaling Maximum SID Depth (MSD) Using OSPF";
       }
     }

     grouping link-msd-sub-tlv {
       description
         "Link Maximum SID Depth (MSD) grouping for an interface.";
       container link-msd-sub-tlv {
         list link-msds {
           key "msd-type";
           leaf msd-type {
             type identityref {
               base msd-base-type;
             }
             description
               "MSD-Types";
           }
           leaf msd-value {
             type uint8;
             description
               "MSD value, in the range of 0-255.";
           }
           description
             "List of link MSDs";
         }
         description

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           "Link MSD sub-tlvs.";
       }
     }

     /* Node MSD 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:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:ri-opaque" {
       when "../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "Node MSD TLV is an optional TLV of OSPFv2 RI Opaque
          LSA (RFC7770) and has a type of 12.";

       uses node-msd-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 "../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "Node MSD TLV is an optional TLV of OSPFv2 RI Opaque
          LSA (RFC7770) and has a type of 12.";

       uses node-msd-tlv;
     }

     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/ospf:router-information" {
       when "../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv3'" {
         description
           "This augmentation is only valid for OSPFv3.";
       }
       description
         "Node MSD TLV is an optional TLV of OSPFv3 RI Opaque
          LSA (RFC7770) and has a type of 12.";

       uses node-msd-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:ospfv3/"
           + "ospf:ospfv3/ospf:body/ospf:router-information" {
       when "../../../../../../../../"
          + "rt:type = 'ospf:ospfv3'" {
         description
           "This augmentation is only valid for OSPFv3.";
       }
       description
         "Node MSD TLV is an optional TLV of OSPFv3 RI Opaque
          LSA (RFC7770) and has a type of 12.";

       uses node-msd-tlv;
     }

     /* link MSD sub-tlv */
     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:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:extended-link-opaque/ospf:extended-link-tlv" {
       when "../../../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description

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         "Link MSD sub-TLV is an optional sub-TLV of OSPFv2 extended
          link TLV as defined in RFC 7684 and has a type of 6.";

       uses link-msd-sub-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:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:extended-link-opaque/ospf:extended-link-tlv" {
       when "../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "Link MSD sub-TLV is an optional sub-TLV of OSPFv2 extended
          link TLV as defined in RFC 7684 and has a type of 6.";

       uses link-msd-sub-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:extended-link-opaque/ospf:extended-link-tlv" {
       when "../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "Link MSD sub-TLV is an optional sub-TLV of OSPFv2 extended
          link TLV as defined in RFC 7684 and has a type of 6.";

       uses link-msd-sub-tlv;
     }

     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" {
          when "'ospf:../../../../../../../../"
            + "rt:type' = 'ospf:ospfv3'" {
            description
              "This augmentation is only valid for OSPFv3
               E-Router LSAs";
          }
       description
         "Augment OSPFv3 Area scope router-link TLV.";

       uses link-msd-sub-tlv;
     }
   }
   <CODE ENDS>

3.  OSPF Segment Routing

   This document defines a model for OSPF Segment Routing feature
   [RFC8665].  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[I-D.ietf-ospf-yang]
   which defines basic OSPF configuration and state.

  module: ietf-ospf-sr
    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*   -> /rt:routing/sr:segment-routing
      |     |                       /sr-mpls:sr-mpls/bindings
      |     |                       /mapping-server/policy/name
      |     +--rw receive?     boolean
      +--rw protocol-srgb {sr-mpls:protocol-srgb}?
         +--rw srgb* [lower-bound upper-bound]
            +--rw lower-bound    uint32
            +--rw upper-bound    uint32
    augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area
            /ospf:interfaces/ospf:interface:

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      +--rw segment-routing
         +--rw adjacency-sid
            +--rw adj-sids* [value]
            |  +--rw value-type?   enumeration
            |  +--rw value         uint32
            |  +--rw protected?    boolean
            |  +--rw weight?       uint8
            +--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:
      +--rw ti-lfa {ti-lfa}?
         +--rw enable?   boolean
    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: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?                            uint8
            +--ro range-size?                    uint16
            +--ro extended-prefix-range-flags
            |  +--ro bits*   identityref
            +--ro prefix?                        inet:ip-prefix
            +--ro prefix-sid-sub-tlvs
            |  +--ro prefix-sid-sub-tlv* []
            |     +--ro prefix-sid-flags
            |     |  +--ro bits*   identityref
            |     +--ro mt-id?              uint8
            |     +--ro algorithm?          uint8
            |     +--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:
      +--ro extended-prefix-range-tlvs
         +--ro extended-prefix-range-tlv* []

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            +--ro prefix-length?                 uint8
            +--ro af?                            uint8
            +--ro range-size?                    uint16
            +--ro extended-prefix-range-flags
            |  +--ro bits*   identityref
            +--ro prefix?                        inet:ip-prefix
            +--ro prefix-sid-sub-tlvs
            |  +--ro prefix-sid-sub-tlv* []
            |     +--ro prefix-sid-flags
            |     |  +--ro bits*   identityref
            |     +--ro mt-id?              uint8
            |     +--ro algorithm?          uint8
            |     +--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?                            uint8
            +--ro range-size?                    uint16
            +--ro extended-prefix-range-flags
            |  +--ro bits*   identityref
            +--ro prefix?                        inet:ip-prefix
            +--ro prefix-sid-sub-tlvs
            |  +--ro prefix-sid-sub-tlv* []
            |     +--ro prefix-sid-flags
            |     |  +--ro bits*   identityref
            |     +--ro mt-id?              uint8
            |     +--ro algorithm?          uint8
            |     +--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:interfaces/ospf:interface/ospf:database
            /ospf:link-scope-lsa-type/ospf:link-scope-lsas
            /ospf:link-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2

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            /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 bits*   identityref
            +--ro mt-id?              uint8
            +--ro algorithm?          uint8
            +--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-prefix-opaque
            /ospf:extended-prefix-tlv:
      +--ro prefix-sid-sub-tlvs
         +--ro prefix-sid-sub-tlv* []
            +--ro prefix-sid-flags
            |  +--ro bits*   identityref
            +--ro mt-id?              uint8
            +--ro algorithm?          uint8
            +--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 bits*   identityref
            +--ro mt-id?              uint8
            +--ro algorithm?          uint8
            +--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 bits*   identityref
      |     +--ro mt-id?           uint8
      |     +--ro weight?          uint8
      |     +--ro sid?             uint32
      +--ro lan-adj-sid-sub-tlvs

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         +--ro lan-adj-sid-sub-tlv* []
            +--ro lan-adj-sid-flags
            |  +--ro bits*   identityref
            +--ro mt-id?                uint8
            +--ro weight?               uint8
            +--ro neighbor-router-id?   yang:dotted-quad
            +--ro sid?                  uint32
    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:ospfv2/ospf:ospfv2
            /ospf:body/ospf:opaque/ospf:ri-opaque:
      +--ro sr-algorithm-tlv
      |  +--ro sr-algorithm*   uint8
      +--ro sid-range-tlvs
      |  +--ro sid-range-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   uint32
      +--ro local-block-tlvs
      |  +--ro local-block-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   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:ospfv2/ospf:ospfv2
            /ospf:body/ospf:opaque/ospf:ri-opaque:
      +--ro sr-algorithm-tlv
      |  +--ro sr-algorithm*   uint8
      +--ro sid-range-tlvs
      |  +--ro sid-range-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   uint32
      +--ro local-block-tlvs
      |  +--ro local-block-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   uint32
      +--ro srms-preference-tlv
         +--ro preference?   uint8
    augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol/ospf:ospf/ospf:database

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            /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*   uint8
      +--ro sid-range-tlvs
      |  +--ro sid-range-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   uint32
      +--ro local-block-tlvs
      |  +--ro local-block-tlv* []
      |     +--ro range-size?    uint24
      |     +--ro sid-sub-tlv
      |        +--ro sid?   uint32
      +--ro srms-preference-tlv
         +--ro preference?   uint8

3.1.  OSPF Segment Routing YANG Module

   <CODE BEGINS> file "ietf-ospf-sr@2022-01-02.yang"
   module ietf-ospf-sr {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-sr";

     prefix ospf-sr;

     import ietf-inet-types {
       prefix "inet";
       reference "RFC 6991 - Common YANG Data Types";
     }

     import ietf-yang-types {
       prefix "yang";
       reference "RFC 6991 - Common YANG Data Types";
     }

     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";
     }

     organization
       "IETF LSR - Link State Routing Working Group";

     contact
        "WG Web:   <http://tools.ietf.org/wg/lsr/>
         WG List:  <mailto:lsr@ietf.org>

         Editor:   Derek Yeung
                   <mailto:derek@arrcus.com>
         Author:   Derek Yeung
                   <mailto:derek@arrcus.com>
         Author:   Yingzhen Qu
                   <mailto:yingzhen.qu@futurewei.com>
         Author:   Acee Lindem
                   <mailto:acee@cisco.com>
         Author:   Jeffrey Zhang
                   <mailto:zzhang@juniper.net>
         Author:   Ing-Wher Chen
                   <mailto:ingwherchen@mitre.org>
         Author:   Greg Hankins
                   <mailto:greg.hankins@alcatel-lucent.com>";

     description
       "This YANG module defines the generic configuration
        and operational state for OSPF Segment Routing, 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 and policies.

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

        Copyright (c) 2022 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to

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        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 2022-01-02 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for OSPF Segment Routing.";
     }

     feature ti-lfa {
       description
         "Topology-Independent Loop-Free Alternate (TI-LFA)
          computation using segment routing.";
     }

     identity prefix-sid-bit {
       description
         "Base identity for prefix sid sub-tlv bits.";
     }

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

     identity m-bit {
       base prefix-sid-bit;
       description

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         "Mapping server flag.";
     }

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

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

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

     identity extended-prefix-range-bit {
       description
         "Base identity for extended prefix range TLV bits.";
     }

     identity ia-bit {
       base extended-prefix-range-bit;
       description
         "Inter-Area flag. If set, advertisement is of inter-area type.";
     }

     identity adj-sid-bit {
       description
         "Base identity for adj sid sub-tlv bits.";
     }

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

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

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

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

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

     typedef uint24 {
       type uint32 {
         range "0 .. 16777215";
       }
       description
         "24-bit unsigned integer.";
     }

     /* Groupings */
     grouping sid-sub-tlv {
       description "SID/Label sub-TLV grouping.";
       container sid-sub-tlv {
         description
           "Used to advertise the SID/Label associated with a
            prefix or adjacency.";
         leaf sid {
           type uint32;
           description
             "Segment Identifier (SID) - A 20 bit label or
              32 bit SID.";
         }
       }
     }

     grouping prefix-sid-sub-tlvs {
       description "Prefix Segment ID (SID) sub-TLVs.";
       container prefix-sid-sub-tlvs{
         description "Prefix SID sub-TLV.";
         list prefix-sid-sub-tlv {
           description "Prefix SID sub-TLV.";

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           container prefix-sid-flags {
             leaf-list bits {
               type identityref {
                 base prefix-sid-bit;
               }
               description
                 "Prefix SID Sub-TLV flag bits list.";
             }
             description "Segment Identifier (SID) Flags.";
           }
           leaf mt-id {
             type uint8;
             description "Multi-topology ID.";
           }
           leaf algorithm {
             type uint8;
             description
               "The algorithm associated with the prefix-SID.";
           }
           leaf sid {
             type uint32;
             description "An index or label.";
           }
         }
       }
     }

     grouping extended-prefix-range-tlvs {
       description "Extended prefix range TLV grouping.";

       container extended-prefix-range-tlvs {
         description "The list of range of prefixes.";
         list extended-prefix-range-tlv {
           description "The range of prefixes.";
           leaf prefix-length {
             type uint8;
             description "Length of prefix in bits.";
           }
           leaf af {
             type uint8;
             description "Address family for the prefix.";
           }
           leaf range-size {
             type uint16;
             description "The number of prefixes covered by the
                          advertisement.";
           }
           container extended-prefix-range-flags {

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             leaf-list bits {
               type identityref {
                 base extended-prefix-range-bit;
               }
               description "Extended prefix range TLV flags list.";
             }
             description "Extended Prefix Range TLV flags.";
           }
           leaf prefix {
             type inet:ip-prefix;
             description "Address prefix.";
           }
           uses prefix-sid-sub-tlvs;
           uses ospf:unknown-tlvs;
         }
       }
     }

     grouping sr-algorithm-tlv {
       description "SR algorithm TLV grouping.";
       container sr-algorithm-tlv {
         description "All SR algorithm TLVs.";
         leaf-list sr-algorithm {
           type uint8;
           description
             "The Segment Routing (SR) algorithms that the router is
              currently using.";
         }
       }
     }

     grouping sid-range-tlvs {
       description "SID Range TLV grouping.";
       container sid-range-tlvs {
         description "List of SID range TLVs.";
         list sid-range-tlv {
           description "SID range TLV.";
           leaf range-size {
             type uint24;
             description "The SID range.";
           }
           uses sid-sub-tlv;
         }
       }
     }

     grouping local-block-tlvs {
       description "The SR local block TLV contains the

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                    range of labels reserved for local SIDs.";
       container local-block-tlvs {
         description "List of SRLB TLVs.";
         list local-block-tlv {
           description "SRLB TLV.";
           leaf range-size {
             type uint24;
             description "The SID range.";
           }
           uses sid-sub-tlv;
         }
       }
     }

     grouping srms-preference-tlv {
       description "The SRMS preference TLV is used to advertise
                    a preference associated with the node that acts
                    as an SR Mapping Server.";
       container srms-preference-tlv {
         description "SRMS Preference TLV.";
         leaf preference {
           type uint8 {
             range "0 .. 255";
           }
           description "SRMS preference TLV, value from 0 to 255.";
         }
       }
     }

     /* Configuration */
     augment "/rt:routing/rt:control-plane-protocols"
           + "/rt:control-plane-protocol/ospf:ospf" {
       when "../rt:type = 'ospf:ospfv2' or "
          + "../rt:type = 'ospf:ospfv3'" {
         description
           "This augments the OSPF routing protocol when used.";
       }
       description
         "This augments the OSPF protocol configuration
          with segment routing.";
       uses sr-mpls:sr-control-plane;
       container protocol-srgb {
         if-feature sr-mpls:protocol-srgb;
         uses sr-cmn:srgb;
         description
           "Per-protocol SRGB.";
       }
     }

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     augment "/rt:routing/rt:control-plane-protocols/"
           + "rt:control-plane-protocol/ospf:ospf/"
           + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface" {
       when "../../../../../rt:type = 'ospf:ospfv2' or "
          + "../../../../../rt:type = 'ospf:ospfv3'" {
         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 "/rt:routing/rt:control-plane-protocols/"
           + "rt:control-plane-protocol/ospf:ospf/"
           + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface/"
           + "ospf:fast-reroute" {
       when "../../../../../../rt:type = 'ospf:ospfv2' or "
          + "../../../../../../rt:type = 'ospf:ospfv3'" {
         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 enable {
           type boolean;
           description
            "Enables TI-LFA computation.";
         }
         description
           "Topology Independent Loop Free Alternate
            (TI-LFA) support.";
       }
     }

     /* Database */
     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:ospfv2/"

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           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:extended-prefix-opaque" {
       when "../../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix LSA
          in type 9 opaque LSA.";

       uses 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" {
       when "../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix LSA
          in type 10 opaque LSA.";

       uses 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 "../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix LSA

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          in type 11 opaque LSA.";

       uses extended-prefix-range-tlvs;
     }

     augment "/rt:routing/"
           + "rt:control-plane-protocols/rt:control-plane-protocol/"
           + "ospf:ospf/ospf:areas/ospf:area/"
           + "ospf:interfaces/ospf:interface/ospf:database/"
           + "ospf:link-scope-lsa-type/ospf:link-scope-lsas/"
           + "ospf:link-scope-lsa/ospf:version/ospf:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" {
       when "../../../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix TLV
          in type 9 opaque LSA.";
       uses 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-prefix-opaque/ospf:extended-prefix-tlv" {
       when "../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix TLV
          in type 10 opaque LSA.";
       uses 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/"

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           + "ospf:ospfv2/ospf:body/ospf:opaque/"
           + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" {
       when "../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended prefix TLV
          in type 11 opaque LSA.";
       uses 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 "../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 extended link TLV
          in type 10 opaque LSA.";

       container adj-sid-sub-tlvs {
         description "Adjacency SID optional sub-TLVs.";
         list adj-sid-sub-tlv {
           description "List of Adjacency SID sub-TLVs.";
           container adj-sid-flags {
             leaf-list bits {
               type identityref {
                 base adj-sid-bit;
               }
               description "Adj sid sub-tlv flags list.";
             }
             description "Adj-sid sub-tlv flags.";
           }
           leaf mt-id {
             type uint8;
             description "Multi-topology ID.";
           }
           leaf weight {

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             type uint8;
             description "Weight used for load-balancing.";
           }
           leaf sid {
             type uint32;
             description "Segment Identifier (SID) index/label.";
           }
         }
       }

       container lan-adj-sid-sub-tlvs {
         description "LAN Adjacency SID optional sub-TLVs.";
         list lan-adj-sid-sub-tlv {
           description "List of LAN adjacency SID sub-TLVs.";
           container lan-adj-sid-flags {
             leaf-list bits {
               type identityref {
                 base adj-sid-bit;
               }
               description "LAN adj sid sub-tlv flags list.";
             }
             description "LAN adj-sid sub-tlv flags.";
           }
           leaf mt-id {
             type uint8;
             description "Multi-topology ID.";
           }
           leaf weight {
             type uint8;
             description "Weight used for load-balancing.";
           }
           leaf neighbor-router-id {
             type yang:dotted-quad;
             description "Neighbor router ID.";
           }
           leaf sid {
             type uint32;
             description "Segment Identifier (SID) index/label.";
           }
         }
       }
     }

     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/"

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           + "ospf:link-scope-lsa/ospf:version/ospf:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" {
       when "../../../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }

       description
         "SR specific TLVs for OSPFv2 type 9 opaque LSA.";

       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:ospfv2/"
           + "ospf:ospfv2/ospf:body/ospf:opaque/ospf:ri-opaque" {
       when "../../../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description
           "This augmentation is only valid for OSPFv2.";
       }

       description
         "SR specific TLVs for OSPFv2 type 10 opaque LSA.";

       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 "../../../../../../../../../"
          + "rt:type = 'ospf:ospfv2'" {
         description

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           "This augmentation is only valid for OSPFv2.";
       }
       description
         "SR specific TLVs for OSPFv2 type 11 opaque LSA.";

       uses sr-algorithm-tlv;
       uses sid-range-tlvs;
       uses local-block-tlvs;
       uses srms-preference-tlv;
     }
   }
   <CODE ENDS>

4.  Security Considerations

   The YANG modules 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 modules 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.

      /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.

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      /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 modules 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.

   Both module ietf-ospf-sr and ietf-ospf-msd augment base OSPF module
   data base with various TLVs.  Knowledge of these data nodes ca be
   used to attack other routers in the OSPF domain.

5.  Acknowledgements

   The authors wish to thank Yi Yang, Alexander Clemm, Gaurav Gupta,
   Ladislav Lhotka, Stephane Litkowski, Greg Hankins, Manish Gupta and
   Alan Davey for their thorough reviews and helpful comments.

   This document was produced using Marshall Rose's xml2rfc tool.

   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.

6.  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
      Registrant Contact: The IESG.
      XML: N/A, the requested URI is an XML namespace.

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

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

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

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

7.  References

7.1.  Normative References

   [I-D.ietf-ospf-yang]
              Yeung, D., Qu, Y., Zhang, J., Chen, I., and A. Lindem,
              "YANG Data Model for OSPF Protocol", Work in Progress,
              Internet-Draft, draft-ietf-ospf-yang-29, 17 October 2019,
              <https://www.ietf.org/archive/id/draft-ietf-ospf-yang-
              29.txt>.

   [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., Giacalone, S., Ed.,
              Coltun, R., and F. Baker, "OSPF Version 2 Management
              Information Base", RFC 4750, DOI 10.17487/RFC4750,
              December 2006, <https://www.rfc-editor.org/info/rfc4750>.

   [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>.

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   [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>.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <https://www.rfc-editor.org/info/rfc7223>.

   [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>.

   [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>.

   [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>.

   [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>.

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   [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>.

   [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>.

7.2.  Informative References

   [RFC8022]  Lhotka, L. and A. Lindem, "A YANG Data Model for Routing
              Management", RFC 8022, DOI 10.17487/RFC8022, November
              2016, <https://www.rfc-editor.org/info/rfc8022>.

   [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>.

Appendix A.  Contributors' Addreses

   Dean Bogdanovic
   Volta Networks, Inc.

   EMail: dean@voltanet.io

   Kiran Koushik Agrahara Sreenivasa
   Cisco Systems
   12515 Research Blvd, Bldg 4
   Austin, TX  78681
   USA

   EMail: kkoushik@cisco.com

Authors' Addresses

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   Derek Yeung
   Arrcus

   Email: derek@arrcus.com

   Yingzhen Qu
   Futurewei
   2330 Central Expressway
   Santa Clara, CA 95050
   United States of America

   Email: yingzhen.qu@futurewei.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

   Acee Lindem
   Cisco Systems
   301 Midenhall Way
   Cary, NC 27513

   Email: acee@cisco.com

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