YANG Module for IS-IS Reverse Metric

<CODE BEGINS> file "ietf-isis-reverse-metric@2022-01-01.yang"
module ietf-isis-reverse-metric {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric";
  prefix isis-rmetric;

  import ietf-routing {
    prefix rt;
    reference
      "RFC8349:
       A YANG Data Model for Routing Management (NMDA Version)";
  }
  import ietf-isis {
    prefix isis;
    reference
      "draft-ietf-isis-yang-isis-cfg-42:
       YANG Data Model for IS-IS Protocol";
  }

  organization
    "IETF LSR Working Group (LSR)";

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

     Author: Christian Hopps
             <mailto:chopps@chopps.org>";

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

  description
    "This module defines the configuration and operational state for
     managing the IS-IS reverse metric functionality [RFC8500].

     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
     the license terms contained in, the Simplified 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.";

  revision 2022-01-01 {
    description "Initial Revision";
    reference "RFC XXXX: YANG IS-IS Reverse Metric";
  }

  grouping reverse-metric-data {
    description "IS-IS reverse metric data.";
    leaf metric {
      type isis:wide-metric;
      description "The reverse metric value.";
      reference "RFC8500, Section 2";
    }
    container flags {
      description "The reverse metric flag values.";
      leaf whole-lan {
        type boolean;
        description
            "The 'whole LAN' or W-bit. If true then a DIS processing
            this reverse metric will add the metric value to all the
            nodes it advertises in the pseudo-node LSP for this
            interface. Otherwise, it will only increment the metric
            for the advertising node in the pseudo-node LSP for this
            interface.";
        reference "RFC8500, Section 2";
      }
      leaf allow-unreachable {
        type boolean;
        description
            "The 'allow-unreachable' or U-bit. If true it allows the
            neighbor to increment the overall metric up to 2^24-1
            rather than the lesser maximum of 2^24-2. If the metric
            is then set by the neighbor to 2^24-1, it will cause
            traffic to stop using, rather than avoid using, the
            interface.";
        reference "RFC8500, Section 2";
      }
    }
  }

  grouping reverse-metric-if-config-data {
    description "IS-IS reverse metric config data.";
    uses reverse-metric-data;
    leaf exclude-te-metric {
      type boolean;
      default false;
      description
        "If true and there is a TE metric defined for this
         interface then do not send the TE metric sub-TLV in the
         reverse metric TLV.";

      reference "RFC8500, Section 2";
    }
  }

  grouping tlv16-reverse-metric {
    description "IS-IS reverse metric TLV data.";
    uses reverse-metric-data;
    leaf te-metric {
      type uint32;
      description
        "The TE metric value from the sub-TLV if present.";
      reference "RFC8500, Section 2";
    }
  }

  augment "/rt:routing/rt:control-plane-protocols/"
    +"rt:control-plane-protocol/"
    +"isis:isis" {
    when "derived-from-or-self(../rt:type, 'isis:isis')" {
      description
        "This augment is only valid when routing protocol instance
         type is 'isis'.";
    }

    description
      "The reverse metric configuration for an IS-IS instance.";

    container reverse-metric {
      description "Global reverse metric configuration.";
      leaf enable-receive {
        type boolean;
        default false;
        description
          "Enable handling of reverse metric announcements from
           neighbors. By default, reverse metric handling is disabled
           and must be explicitly enabled through this
           configuration.";
      }
    }
  }

  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 augment is only valid when routing protocol instance
         type is 'isis'.";
    }

    description
      "The reverse metric configuration for an interface.";

    container reverse-metric {
      description
        "Announce a reverse metric to neighbors. The configuration
         is hierarchical and follows the same behavior as defined
         for 'Per-Level' values in the augmented base module.

         Reverse metric operation is enabled by the configuration of
         a reverse-metric metric value at either the top level or
         under a level-specific container node. If a reverse-metric
         metric value is only specified under a level-specific
         container node then operation is only enabled at the
         specified level.

         As the reverse metric is advertised in IIH PDUs, level
         specific configuration is only available for broadcast
         interface types";
      uses reverse-metric-if-config-data {
        refine "flags/whole-lan" {
          default false;
        }
        refine "flags/allow-unreachable" {
          default false;
        }
      }
      container level-1 {
        when '../../isis:interface-type = "broadcast"';
        description
          "Announce a reverse metric to level-1 neighbors.";
        uses reverse-metric-if-config-data;
      }
      container level-2 {
        when '../../isis:interface-type = "broadcast"';
        description
          "Announce a reverse metric to level-2 neighbors.";
        uses reverse-metric-if-config-data;
      }
    }
  }
  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 augment is only valid when routing protocol instance
         type is 'isis'";
    }

    description
      "The reverse metric state advertised by an adjacency.";
    container reverse-metric {
      description "IS-IS reverse metric TLV data.";
      uses tlv16-reverse-metric;
    }
  }
}
<CODE ENDS>