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A YANG Module for IS-IS Reverse Metric
draft-ietf-lsr-yang-isis-reverse-metric-06

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9194.
Author Christian Hopps
Last updated 2022-10-19 (Latest revision 2022-01-01)
Replaces draft-hopps-lsr-yang-isis-reverse-metric
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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Additional resources Yang catalog entry for ietf-isis-reverse-metric@2020-07-28.yang
Yang impact analysis for draft-ietf-lsr-yang-isis-reverse-metric
Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Acee Lindem
Shepherd write-up Show Last changed 2021-08-16
IESG IESG state Became RFC 9194 (Proposed Standard)
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Responsible AD John Scudder
Send notices to acee@cisco.com, jgs@juniper.net
IANA IANA review state IANA OK - Actions Needed
IANA action state RFC-Ed-Ack
IANA expert review state Expert Reviews OK
draft-ietf-lsr-yang-isis-reverse-metric-06
Network Working Group                                           C. Hopps
Internet-Draft                                   LabN Consulting, L.L.C.
Intended status: Standards Track                          1 January 2022
Expires: 5 July 2022

                  YANG Module for IS-IS Reverse Metric
               draft-ietf-lsr-yang-isis-reverse-metric-06

Abstract

   This document defines a YANG module for managing the reverse metric
   extension to the Intermediate System to Intermediate System intra-
   domain routeing information exchange protocol (IS-IS).

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 5 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.
   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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  YANG Management . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  YANG Tree . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Updates to the IETF XML Registry  . . . . . . . . . . . .   8
     3.2.  Updates to the YANG Module Names Registry . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .  10
   6.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  12
     A.1.  Enablement Example using XML YANG Instance Data . . . . .  12
     A.2.  Usage Example using XML YANG Instance Data  . . . . . . .  13
     A.3.  Usage Example using JSON YANG Instance Data . . . . . . .  14
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   This document defines a YANG module for managing the reverse metric
   extension to IS-IS [RFC8500], [ISO10589].  Please refer to [RFC8500]
   for the description and definition of the functionality managed by
   this module.

   The YANG data model described in this document conforms to the
   Network Management Datastore Architecture defined in [RFC8342].

2.  YANG Management

2.1.  YANG Tree

   The following is the YANG tree diagram ([RFC8340]) for the IS-IS
   reverse metric extension additions.

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   module: ietf-isis-reverse-metric
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/isis:isis:
       +--rw reverse-metric
          +--rw enable-receive?   boolean
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/isis:isis/isis:interfaces
               /isis:interface:
       +--rw reverse-metric
          +--rw metric?              isis:wide-metric
          +--rw flags
          |  +--rw whole-lan?           boolean
          |  +--rw allow-unreachable?   boolean
          +--rw exclude-te-metric?   boolean
          +--rw level-1
          |  +--rw metric?              isis:wide-metric
          |  +--rw flags
          |  |  +--rw whole-lan?           boolean
          |  |  +--rw allow-unreachable?   boolean
          |  +--rw exclude-te-metric?   boolean
          +--rw level-2
             +--rw metric?              isis:wide-metric
             +--rw flags
             |  +--rw whole-lan?           boolean
             |  +--rw allow-unreachable?   boolean
             +--rw exclude-te-metric?   boolean
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/isis:isis/isis:interfaces
               /isis:interface/isis:adjacencies/isis:adjacency:
       +--ro reverse-metric
          +--ro metric?      isis:wide-metric
          +--ro flags
          |  +--ro whole-lan?           boolean
          |  +--ro allow-unreachable?   boolean
          +--ro te-metric?   uint32

2.2.  YANG Module

   The following is the YANG module for managing the IS-IS reverse
   metric functionality defined in [RFC8500].  It imports modules from
   the following RFCs: [RFC8349], [I-D.ietf-isis-yang-isis-cfg].

   This YANG module uses the same "Per-Level" hierarchical configuration
   structure as is defined in the augmented base module.

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   <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

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        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

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           "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" {

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       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/"

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       +"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>

3.  IANA Considerations

3.1.  Updates to the IETF XML Registry

   This document registers a URI in the "IETF XML Registry" [RFC3688].
   Following the format in [RFC3688], the following registration has
   been made:

   URI  urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric

   Registrant Contact  The IESG.

   XML  N/A; the requested URI is an XML namespace.

3.2.  Updates to the YANG Module Names Registry

   This document registers one YANG module in the "YANG Module Names"
   registry [RFC6020].  Following the format in [RFC6020], the following
   registration has been made:

   name  ietf-isis-reverse-metric

   namespace  urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric

   prefix  isis-rmetric

   reference  RFC XXXX (RFC Ed.: replace XXX with actual RFC number and
      remove this note.)

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4.  Security Considerations

   The YANG module specified in this document defines 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 access control model [RFC8341] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.

   The YANG module defined in this document can enable, disable and
   modify the behavior of metrics used by routing.  For the security
   implications regarding these types of changes consult [RFC8500] which
   defines the functionality as well as [I-D.ietf-isis-yang-isis-cfg].

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., "config true", which is the
   default).  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 YANG nodes correspond directly
   to the RFC 8500 functionality and the security considerations of the
   functionality are described in RFC 8500.

   These are the subtrees and data nodes:

   Under "/rt:routing/rt:control-plane-protocols/" +
         "rt:control-plane-protocol/isis:isis"

     - /isis-rmetric:reverse-metric/isis-rmetric:enable-receive

   Under "/rt:routing/rt:control-plane-protocols/" +
         "rt:control-plane-protocol/isis:isis/" +
         "isis:interfaces/isis:interface/" +
         "isis-rmetric:reverse-metric"

     - /isis-rmetric:metric
     - /isis-rmetric:flags/isis-rmetric:whole-lan
     - /isis-rmetric:flags/isis-rmetric:allow-unreachable
     - /isis-rmetric:exclude-te-metric

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   Under "/rt:routing/rt:control-plane-protocols/" +
         "rt:control-plane-protocol/isis:isis/" +
         "isis:interfaces/isis:interface/" +
         "isis-rmetric:reverse-metric/" +
         "isis-rmetric:level-1/"

     - /isis-rmetric:metric
     - /isis-rmetric:flags/isis-rmetric:whole-lan
     - /isis-rmetric:flags/isis-rmetric:allow-unreachable
     - /isis-rmetric:exclude-te-metric

   Under "/rt:routing/rt:control-plane-protocols/" +
         "rt:control-plane-protocol/isis:isis/" +
         "isis:interfaces/isis:interface/" +
         "isis-rmetric:reverse-metric/" +
         "isis-rmetric:level-2/"

     - /isis-rmetric:metric
     - /isis-rmetric:flags/isis-rmetric:whole-lan
     - /isis-rmetric:flags/isis-rmetric:allow-unreachable
     - /isis-rmetric:exclude-te-metric

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These YANG nodes correspond
   directly to the RFC 8500 functionality and the security
   considerations of the functionality are described in RFC 8500.  These
   are the subtrees and data nodes:

   Under "/rt:routing/rt:control-plane-protocols/" +
         "rt:control-plane-protocol/isis:isis/" +
         "isis:interfaces/isis:interface/" +
         "isis:adjacencies/isis:adjacency/" +
         "isis-rmetric:reverse-metric"

       - /isis-rmetric:metric
       - /isis-rmetric:flags/isis-rmetric:whole-lan
       - /isis-rmetric:flags/isis-rmetric:allow-unreachable
       - /isis-rmetric:te-metric

5.  Normative References

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   [ISO10589] International Organization for Standardization,
              "Intermediate System to Intermediate System intra-domain
              routeing information exchange protocol for use in
              conjunction with the protocol for providing the
              connectionless-mode network service (ISO 8473)", ISO
              Standard 10589:2002, 2002.

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

   [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>.

   [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>.

   [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>.

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

   [RFC8500]  Shen, N., Amante, S., and M. Abrahamsson, "IS-IS Routing
              with Reverse Metric", RFC 8500, DOI 10.17487/RFC8500,
              February 2019, <https://www.rfc-editor.org/info/rfc8500>.

   [I-D.ietf-isis-yang-isis-cfg]
              Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L.
              Lhotka, "YANG Data Model for IS-IS Protocol", Work in
              Progress, Internet-Draft, draft-ietf-isis-yang-isis-cfg-
              42, 15 October 2019,
              <https://datatracker.ietf.org/doc/html/draft-ietf-isis-
              yang-isis-cfg-42>.

6.  Informative References

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   [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>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

   [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>.

   [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>.

   [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>.

Appendix A.  Examples

A.1.  Enablement Example using XML YANG Instance Data

   Below is an example of XML YANG instance data [RFC8342] to enable
   reverse metric processing.

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   <rt:routing
       xmlns:rt="urn:ietf:params:xml:ns:yang:ietf-routing"
       xmlns:isis="urn:ietf:params:xml:ns:yang:ietf-isis"
       xmlns:isis-rmetric=
       "urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric">
     <rt:control-plane-protocols>
       <rt:control-plane-protocol>
         <rt:type>isis:isis</rt:type>
         <rt:name>default</rt:name>
         <isis:isis>
           <isis:area-address>00</isis:area-address>
           <isis-rmetric:reverse-metric>
        <isis-rmetric:enable-receive>true</isis-rmetric:enable-receive>
           </isis-rmetric:reverse-metric>
         </isis:isis>
       </rt:control-plane-protocol>
     </rt:control-plane-protocols>
   </rt:routing>

      Figure 1: Example XML data to enable reverse metric processing.

A.2.  Usage Example using XML YANG Instance Data

   Below is an example of XML YANG instance data [RFC8342] for the ietf-
   isis-reverse-metric module.

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   <if:interfaces
       xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces"
       xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
     <if:interface>
       <if:name>eth0</if:name>
       <if:type>ianaift:ethernetCsmacd</if:type>
     </if:interface>
   </if:interfaces>
   <rt:routing
       xmlns:rt="urn:ietf:params:xml:ns:yang:ietf-routing"
       xmlns:isis="urn:ietf:params:xml:ns:yang:ietf-isis"
       xmlns:isis-rmetric=
       "urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric">
     <rt:control-plane-protocols>
       <rt:control-plane-protocol>
         <rt:type>isis:isis</rt:type>
         <rt:name>default</rt:name>
         <isis:isis>
           <isis:area-address>00</isis:area-address>
           <isis:interfaces>
             <isis:interface>
               <isis:name>eth0</isis:name>
               <isis-rmetric:reverse-metric>
                 <isis-rmetric:metric>
                   65535
                 </isis-rmetric:metric>
               </isis-rmetric:reverse-metric>
             </isis:interface>
           </isis:interfaces>
         </isis:isis>
       </rt:control-plane-protocol>
     </rt:control-plane-protocols>
   </rt:routing>

      Figure 2: Example XML data for ietf-isis-reverse-metric module.

A.3.  Usage Example using JSON YANG Instance Data

   Below is an example of JSON YANG instance data [RFC7951] for the
   ietf-isis-reverse-metric module.

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Internet-Draft    YANG Module for IS-IS Reverse Metric      January 2022

   {
     "ietf-interfaces:interfaces": {
       "interface": [
         {
           "name": "eth0",
           "type": "iana-if-type:ethernetCsmacd"
         }
       ]
     },
     "ietf-routing:routing": {
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-isis:isis",
             "name": "default",
             "ietf-isis:isis": {
               "area-address": [
                 "00"
               ],
               "interfaces": {
                 "interface": [
                   {
                     "name": "eth0",
                     "ietf-isis-reverse-metric:reverse-metric": {
                       "level-1": {
                         "metric": 65535,
                         "exclude-te-metric": true
                       }
                     }
                   }
                 ]
               }
             }
           }
         ]
       }
     }
   }

        Figure 3: Example JSON data for level-1 only reverse metric.

Author's Address

   Christian Hopps
   LabN Consulting, L.L.C.

   Email: chopps@chopps.org

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