A YANG Data Model for IS-IS Segment Routing over the MPLS Data Plane

    <CODE BEGINS> file "ietf-isis-sr-mpls@2025-04-22.yang"
module ietf-isis-sr-mpls {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-isis-sr-mpls";
  prefix isis-sr-mpls;

  import ietf-routing {
    prefix rt;
    reference
      "RFC 8349: A YANG Data Model for Routing
                  Management (NMDA Version)";
  }
  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types";
  }
  import ietf-segment-routing-common {
    prefix sr-cmn;
    reference
      "RFC 9020: YANG Data Model for Segment Routing";
  }
  import ietf-segment-routing-mpls {
    prefix sr-mpls;
    reference
      "RFC 9020: YANG Data Model for Segment Routing";
  }
  import ietf-isis {
    prefix isis;
    reference
      "RFC 9130: YANG Data Model for IS-IS Protocol";
  }
  import iana-routing-types {
    prefix iana-rt-types;
    reference
      "RFC 8294: Common YANG Data Types for the Routing Area";
  }
  import ietf-routing-types {
    prefix rt-types;
    reference
      "RFC 8294: Common YANG Data Types for the Routing Area";
  }

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

     Author:    Stephane Litkowski
                <mailto:slitkows.ietf@gmail.com>
     Author:    Yingzhen Qu
                <mailto:yingzhen.ietf@gmail.com>
     Author:    Acee Lindem
                <mailto:acee.ietf@gmail.com>
     Author:    Ing-Wher Chen
                <mailto:ingwherchen@mitre.org>
     Author:    Jeff Tantsura
                <mailto:jefftant.ietf@gmail.com>
    ";
  description
    "The YANG module defines the generic configuration and
     operational state for Segment Routing ISIS extensions 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
     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.";

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

  revision 2025-04-22 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: A YANG Data Model for IS-IS Segment Routing over the
                 MPLS Data Plane";
  }

  // RFC Ed.: Replace XXXX with actual RFC number.
  // Also, replace '2025-04-22' with the module publication date
  // in the format (YYYY-MM-DD) and remove this note.

  /* Features */

  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";
  }

  /* Identities */

  identity sr-capability {
    description
      "Base identity for ISIS SR-Capabilities sub-TLV flags";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing";
  }

  identity mpls-ipv4 {
    base sr-capability;
    description
      "If set, then the router is capable of
       processing SR MPLS encapsulated IPv4 packets
       on all interfaces.";
  }

  identity mpls-ipv6 {
    base sr-capability;
    description
      "If set, then the router is capable of
       processing SR MPLS encapsulated IPv6 packets
       on all interfaces.";
  }

  identity prefix-sid-flag {
    description
      "Base identity for prefix SID sub-TLV flags.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity r-flag {
    base prefix-sid-flag;
    description
      "Re-advertisement Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity n-flag {
    base prefix-sid-flag;
    description
      "Node-SID Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity p-flag {
    base prefix-sid-flag;
    description
      "No-PHP (No Penultimate Hop-Popping) Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity e-flag {
    base prefix-sid-flag;
    description
      "Explicit NULL Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity v-flag {
    base prefix-sid-flag;
    description
      "Value Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity l-flag {
    base prefix-sid-flag;
    description
      "Local Flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
  }

  identity adj-sid-flag {
    description
      "Base identity for Adj-SID sub-TLV flags.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity f-flag {
    base adj-sid-flag;
    description
      "Address-Family flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity b-flag {
    base adj-sid-flag;
    description
      "Backup flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity vi-flag {
    base adj-sid-flag;
    description
      "Value/Index flag - corresponds to V-Flag in reference.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity lg-flag {
    base adj-sid-flag;
    description
      "Local/Global flag - corresponds to L-Flag in reference.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity s-flag {
    base adj-sid-flag;
    description
      "Set flag - corresponds to S-Flag in reference..";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity pe-flag {
    base adj-sid-flag;
    description
      "Persistent flag - corresponds to P-Flag in reference.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
  }

  identity sid-binding-flag {
    description
      "Base identity for sid binding tlv flags.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  identity af-flag {
    base sid-binding-flag;
    description
      "Address-Family flag - corresponds to F-Flag in reference.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  identity m-flag {
    base sid-binding-flag;
    description
      "Mirror Context flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  identity sf-flag {
    base sid-binding-flag;
    description
      "S flag. If set, the binding label TLV should be flooded
       across the entire routing domain - corresponds to S-Flag in
       reference.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  identity d-flag {
    base sid-binding-flag;
    description
      "Leaking flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  identity a-flag {
    base sid-binding-flag;
    description
      "Attached flag.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
  }

  /* Groupings */

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

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

        If 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.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1.1.1";
    choice sid {
      case sid-label {
        leaf label-value {
          type uint32 {
            range "0 .. 1048575";
          }
          description
            "A 20-bit MPLS Label";
        }
      }
      case sid-index {
        leaf index-value {
          type uint32;
          description
            "Index into a label space advertised by this router.";
        }
      }
      description
        "Choice of either a 20-bit MPLS label or 32-bit index into
         an advertised label space.";
    }
  }

  grouping sid-sub-tlv {
    description
      "SID/Label sub-TLV grouping.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.4";
    container sid-sub-tlv {
      description
        "Used to advertise the SID/Label associated with a
         prefix or adjacency.";
      leaf length {
        type uint8;
        description
          "Length of the SID value. YANG model specification
           is necessary since it dictates the semantics of the
           SID.";
      }
      uses sid-tlv-encoding;
    }
  }

  grouping sr-capability {
    description
      "SR capability grouping.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 3.1";
    container sr-capability {
      description
        "SR Capability Flags.";
      leaf-list sr-capability-flag {
        type identityref {
          base sr-capability;
        }
        description
          "SR Capability sub-TLV flags.";
      }
      container global-blocks {
        description
          "Segment Routing Global Blocks.";
        list global-block {
          description
            "Segment Routing Global Block.";
          leaf range-size {
            type rt-types:uint24;
            description
              "The SID range.";
          }
          uses sid-sub-tlv;
        }
      }
    }
  }

  grouping sr-algorithm {
    description
      "SR algorithm grouping.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 3.2";
    container sr-algorithms {
      description
        "All SR algorithms.";
      leaf-list sr-algorithm {
        type identityref {
          base sr-cmn:prefix-sid-algorithm;
        }
        description
          "The Segment Routing (SR) algorithms that the router is
           currently using.";
      }
    }
  }

  grouping srlb {
    description
      "SR Local Block grouping.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 3.3";
    container local-blocks {
      description
        "List of SRLBs.";
      list local-block {
        description
          "Segment Routing Local Block.";
        leaf range-size {
          type rt-types:uint24;
          description
            "The SID range.";
        }
        uses sid-sub-tlv;
      }
    }
  }

  grouping srms-preference {
    description
      "The SRMS preference TLV is used to advertise
       a preference associated with the node that acts
       as an SR Mapping Server.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 3.4";
    container srms-preference {
      description
        "SRMS Preference TLV.";
      leaf preference {
        type uint8;
        description
          "SRMS preference TLV, value from 0 to 255 with
           255 being the most preferred.";
      }
    }
  }

  grouping adjacency-state {
    description
      "This grouping extends adjacency state.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
    list adjacency-sid {
      config false;
      description
        "List of adjacency Segment IDs.";
      leaf value {
        type uint32;
        description
          "Value of the Adj-SID.";
      }
      leaf address-family {
        type iana-rt-types:address-family;
        description
          "Address-family associated with the
           segment ID";
      }
      leaf weight {
        type uint8;
        description
          "Weight associated with
           the adjacency SID.";
      }
      leaf protection-requested {
        type boolean;
        description
          "Describe if the adjacency SID
           must be protected.";
      }
    }
  }

  grouping prefix-sid-sub-tlv {
    description
      "This grouping defines segment routing prefix segment
       identifier (prefix-sid) sub-tlv.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.1";
    container prefix-sid-sub-tlvs {
      description
        "PrefixSID sub-tlvs.";
      list prefix-sid-sub-tlv {
        description
          "List of prefix-sid sub-tlvs.";
        container prefix-sid-flags {
          description
            "Describes flags associated with the
             segment ID.";
          leaf-list flag {
            type identityref {
              base prefix-sid-flag;
            }
            description
              "Prefix SID sub-TLV flags.";
          }
        }
        leaf algorithm {
          type identityref {
            base sr-cmn:prefix-sid-algorithm;
          }
          description
            "Algorithm to be used for path computation.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping adjacency-segment-id {
    description
      "This grouping defines segment routing extensions
       for adjacencies.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing, Section 2.2";
    container adj-sid-sub-tlvs {
      description
        "Adj-SID optional sub-TLVs.";
      list adj-sid-sub-tlv {
        description
          "List of segments.";
        container adj-sid-flags {
          description
            "Adj-SID sub-TLV flags.";
          leaf-list flag {
            type identityref {
              base adj-sid-flag;
            }
            description
              "Adj-SID sub-TLV flags list.";
          }
        }
        leaf weight {
          type uint8;
          description
            "The value represents the weight of the Adj-SID
             for the purpose of load balancing.";
        }
        leaf neighbor-id {
          type isis:system-id;
          description
            "Describes the system ID of the neighbor
             associated with the SID value. This is only
             used on LAN adjacencies.";
        }
        uses sid-tlv-encoding;
      }
    }
  }

  grouping sid-binding-tlv {
    description
      "SID/Label binding TLV, type 149.";
    reference
      "RFC 8667: IS-IS Extensions for Segment Routing,
       Section 2.4";
    leaf prefix {
      type inet:ip-prefix;
      description
        "The prefix represents the Forwarding Equivalence
         Class at the tail end of the advertised path.";
    }
    leaf range {
      type uint16;
      description
        "Provides the ability to specify a range of addresses
         and their associated prefix-sids.";
    }
    container sid-binding-flags {
      description
        "Binding TLV flags.";
      leaf-list flag {
        type identityref {
          base sid-binding-flag;
        }
        description
          "SID Binding TLV flags.";
      }
    }
    list prefix-sid-sub-tlvs {
      description
        "List of prefix-sid sub-tlvs.";
      reference
        "RFC 8667: IS-IS Extensions for Segment Routing,
         Section 2.4.4";
      uses prefix-sid-sub-tlv;
    }
    list sid-sub-tlv {
      description
        "List of prefix-sid sub-tlvs.";
      reference
        "RFC 8667: IS-IS Extensions for Segment Routing,
         Section 2.4.5";
      uses sid-sub-tlv;
    }
    uses isis:unknown-tlvs;
  }

  /* Configuration */

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis" {
    when "derived-from-or-self(../rt:type, 'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol configuration
       with segment routing for the MPLS data plane.";
    uses sr-mpls:sr-control-plane;
    container protocol-srgb {
      if-feature "sr-mpls:protocol-srgb";
      description
        "Per-protocol Segment Routing Global Block (SRGB).";
      reference
        "RFC 8402: Segment Routing Architecture, Section 2";
      uses sr-cmn:srgb;
    }
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface" {
    when "derived-from-or-self(../../../rt:type, 'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol configuration
       with segment routing.";
    uses sr-mpls:igp-interface {
      augment "segment-routing/adjacency-sid/adj-sids" {
        when "../../../isis:interface-type = 'broadcast'" {
          description
            "This augments broadcast interface.";
        }
        description
          "This augments LAN interface adj-sid with system-id.";
        leaf neighbor-system-id {
          type isis:system-id;
          mandatory true;
          description
            "Neighbor system ID.";
        }
      }
    }
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface"
        + "/isis:fast-reroute/isis:lfa" {
    when "derived-from-or-self(../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS interface IP FRR with TILFA.";
    container ti-lfa {
      if-feature "ti-lfa";
      description
        "Topology Independent Loop Free Alternate
         (TI-LFA) support.";
      leaf enabled {
        type boolean;
        default "false";
        description
          "Enables TI-LFA computation.";
      }
      container selection-tie-breakers {
        description
          "Configure path selection tie-breakers and their
           respective priorities for the TI-LFA computation.";
        container node-protection {
          presence "Presence of container enables the node
                    protection tie-breaker";
          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.";
          leaf priority {
            type uint8;
            default "128";
            description
              "Priority for node protection tie-breaker with
               a lower priority being more preferred.";
          }
        }
        container srlg-disjoint {
          presence "Presence of container enables the SRLG
                    disjoint tie-breaker";
          description
            "Enable SRLG (Shared 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.";
          leaf priority {
            type uint8;
            default "128";
            description
              "Priority for SRLG disjoint tie-breaker with
               a lower priority being more preferred.";
          }
        }
      }
    }
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface"
        + "/isis:fast-reroute/isis:lfa/isis:level-1" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS interface level-1 IP FRR with TILFA.";
    container ti-lfa {
      if-feature "ti-lfa";
      description
        "TI-LFA configuration.";
      leaf enabled {
        type boolean;
        default "false";
        description
          "Enables TI-LFA computation.";
      }
    }
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface"
        + "/isis:fast-reroute/isis:lfa/isis:level-2" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS IP interface level-2 FRR with TILFA.";
    container ti-lfa {
      if-feature "ti-lfa";
      description
        "TI-LFA configuration.";
      leaf enabled {
        type boolean;
        default "false";
        description
          "Enables TI-LFA computation.";
      }
    }
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface"
        + "/isis:fast-reroute/isis:lfa/isis:remote-lfa" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS remoteLFA config with
       use of segment-routing path.";
    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.";
    }
  }

  /* Operational states */

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:interfaces/isis:interface"
        + "/isis:adjacencies/isis:adjacency" {
    when "derived-from-or-self(../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol configuration
       with segment routing.";
    uses adjacency-state;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:router-capabilities/isis:router-capability" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB router capability.";
    uses sr-capability;
    uses sr-algorithm;
    uses srlb;
    uses srms-preference;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:extended-is-neighbor/isis:neighbor/isis:instances"
        + "/isis:instance" {
    when "derived-from-or-self(../../../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB neighbor.";
    uses adjacency-segment-id;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:mt-is-neighbor/isis:neighbor/isis:instances"
        + "/isis:instance" {
    when "derived-from-or-self(../../../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB neighbor.";
    uses adjacency-segment-id;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:extended-ipv4-reachability/isis:prefixes" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB prefix.";
    uses prefix-sid-sub-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:mt-extended-ipv4-reachability/isis:prefixes" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB prefix.";
    uses prefix-sid-sub-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:ipv6-reachability/isis:prefixes" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB prefix.";
    uses prefix-sid-sub-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp"
        + "/isis:mt-ipv6-reachability/isis:prefixes" {
    when "derived-from-or-self(../../../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB prefix.";
    uses prefix-sid-sub-tlv;
  }

  augment "/rt:routing/"
        + "rt:control-plane-protocols/rt:control-plane-protocol"
        + "/isis:isis/isis:database/isis:levels/isis:lsp" {
    when "derived-from-or-self(../../../../rt:type,"
       + "'isis:isis')" {
      description
        "This augments ISIS routing protocol when used";
    }
    description
      "This augments ISIS protocol LSDB.";
    container sid-binding-tlvs {
      description
        "List of sid/label binding TLVs.";
      list sid-binding-tlv {
        key "prefix";
        description
          "Sid/label binding TLV, type 149.";
        uses sid-binding-tlv;
      }
    }
    container mt-sid-binding-tlvs {
      description
        "List of multi-topology sid/label binding TLVs.";
      list mt-sid-binding-tlv {
        key "prefix mt-id";
        description
          "Multi-Topology SID/Label binding TLV, type 150.";
        reference
          "RFC 8667: IS-IS Extensions for Segment Routing,
           Section 2.5";
        uses sid-binding-tlv;
        leaf mt-id {
          type uint16;
          description
            "A 12-bit field containing the non-zero ID
             of the topology.";
        }
      }
    }
  }
}
<CODE ENDS>