Internet DRAFT - draft-ogondio-opsawg-isis-topology

draft-ogondio-opsawg-isis-topology







opsawg                                                     O. G. D. Dios
Internet-Draft                                                Telefonica
Intended status: Standards Track                           S. B. Giraldo
Expires: 25 April 2024                                          V. Lopez
                                                                   Nokia
                                                           D. Ceccarelli
                                                                   Cisco
                                                               B. Claise
                                                                  Huawei
                                                         23 October 2023


A YANG Data Model for Intermediate System to intermediate System (IS-IS)
                                Topology
                 draft-ogondio-opsawg-isis-topology-01

Abstract

   This document defines a YANG data model for representing an
   abstracted view of a network topology that contains Intermediate
   System to Intermediate System (IS-IS).  This document augments the
   'ietf-network' data model by adding IS-IS concepts and explains how
   the data model can be used to represent the IS-IS topology.

   The YANG data model defined in this document conforms to the Network
   Management Datastore Architecture (NMDA).

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 25 April 2024.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology and Notations . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.3.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   3
     1.4.  Prefix in Data Node Names . . . . . . . . . . . . . . . .   4
   2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Relationship with the IS-IS YANG Model  . . . . . . . . .   5
     2.2.  Relationship with Digital Map . . . . . . . . . . . . . .   5
   3.  Use of IETF-Topology for Representing an IP/MPLS network
           domain  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  YANG Data Model for IS-IS Topology  . . . . . . . . . . . . .   6
   5.  IS-IS Topology Tree Diagram . . . . . . . . . . . . . . . . .   8
   6.  YANG Model for IS-IS topology . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  15
   Appendix A.  Implementation Status  . . . . . . . . . . . . . . .  17
     A.1.  Implementation Status in Telefonica Group . . . . . . . .  17
     A.2.  Huawei Digital Map PoC Status . . . . . . . . . . . . . .  17
     A.3.  Implementation Status in E-lighthouse Network
           Solutions . . . . . . . . . . . . . . . . . . . . . . . .  17
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  18
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   Network operators perform the capacity planning for their networks
   and run regular what-if scenarios analysis based on representations
   of the real network.  Those what-if analysis and capacity planning
   processes require, among other information, a topological view
   (domains, nodes, links, network interconnection) of the deployed
   network.

   This document defines a YANG data model representing an abstracted
   view of a network topology containing Intermediate System to
   Intermediate System (IS-IS).  It covers the topology of IP/MPLS



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   networks running IS-IS as Interior Gateway Protocol (IGP) protocol.
   The proposed YANG mode augments the "A YANG Data Model for Network
   Topologies" [RFC8345] and"A YANG Data Model for Layer 3 Topologies"
   [RFC8346] by adding IS-IS concepts.  This YANG data model is used to
   export the IS-IS related topology directly from a network controller
   to an Operation Support System (OSS) tools.

   Note that the YANG model is in this document strictly adheres to the
   concepts (and the YANG module) in "A YANG Data Model for Network
   Topologies" [RFC8345] and"A YANG Data Model for Layer 3 Topologies"
   [RFC8346].  While investigating the IS-IS topology, some limitations
   have discovered in [RFC8345], regarding how the digital map can be
   represented.  Those limitations (and potential improvements) are
   covered in [I-D.draft-havel-opsawg-digital-map].

   This document explains the scope and purpose of the IS-IS topology
   model and how the topology and service models fit together.  The YANG
   data model defined in this document conforms to the Network
   Management Datastore Architecture [RFC8342].

1.1.  Terminology and Notations

   This document assumes that the reader is familiar with IS-IS and the
   contents of [RFC8345].  The document uses terms from those documents.

   The terminology for describing YANG data models is found in
   [RFC7950], [RFC8795] and [RFC8346].

   The term Digital Twin, Digital Map, Digital Map Modelling, Digital
   Map Model, Digital Map Data, and Topology are specified in
   [I-D.draft-havel-opsawg-digital-map].

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119], [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.3.  Tree Diagram

   Authors include a simplified graphical representation of the data
   model is used in Section 5 of this document.  The meaning of the
   symbols in these diagrams is defined in [RFC8340].






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1.4.  Prefix in Data Node Names

   In this document, names of data nodes and other data model objects
   are prefixed using the standard prefix associated with the
   corresponding YANG imported modules, as shown in the following table.

              +========+=======================+===========+
              | Prefix | Yang Module           | Reference |
              +========+=======================+===========+
              | isisnt | ietf-l3-isis-topology | RFCXXX    |
              +--------+-----------------------+-----------+
              | yang   | ietf-yang-types       | [RFC6991] |
              +--------+-----------------------+-----------+

                 Table 1: Prefixes and corresponding YANG
                                 modules

   RFC Editor Note: Please replace XXXX with the RFC number assigned to
   this document.  Please remove this note.

2.  Use Cases

   This information is required in the IP/MPLS planning process to
   properly assess the required network resources to meet the traffic
   demands in normal and failure scenarios.  Network operators perform
   the capacity planning for their networks and run regular what-if
   scenarios analysis based on representations of the real network.
   Those what-if analysis and capacity planning processes require, among
   other information, a topological view (domains, nodes, links, network
   interconnection) of the deployed network.

   The standardization of an abstracted view of the IS-IS topology model
   as NorthBound Interface (NBI) of Software Defined Networking (SDN)
   controllers allows the inject this information into third party tools
   covering specialized cases.

   The IS-IS topological model should export enough IS-IS information to
   permit these tools simulating the IP routing.  By adding the traffic
   demand, ideally at the IP flow level, we can simulate the traffic
   growth and its effect on the routing.  That is, simulating how IP-
   level traffic demands would be forwarded, after IS-IS convergence is
   reached, and from there estimating, using appropriate mathematical
   models, related KPIs like the occupation in the links or end-to-end
   latencies.

   In summary, the network-wide view of the IS-IS topology enables
   multiple use cases:




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   *  Network design: verifying that the actual deployed IS-IS network
      conforms to the planned design

   *  Failure analysis.  Systematic and massive test of the network
      under multiple simulated failure situations, evaluating the
      network fault tolerance properties, and using mathematical models
      to derive statistical network availability metrics.

   *  What-if analysis.  Estimation of the network KPIs in modified
      network situations.  For instance, failure situations, traffic
      anomaly situations, addition or deletion of new adjacencies, IGP
      weight reconfigurations.

   *  Capacity planning.  Dimensioning or redesign of the IP
      infrastructure to satisfy target KPI metrics under existing or
      forecasted traffic demands.

2.1.  Relationship with the IS-IS YANG Model

   [RFC9130] specifies a YANG data model that can be used to configure
   and manage the IS-IS protocol on network elements.  This data model
   covers the configuration of an IS-IS routing protocol instance, as
   well as the retrieval of IS-IS operational states.  [RFC9130] is
   still expected to be used for individual network elements
   configuration and monitoring.  On the other hand, the proposed YANG
   model in this document covers the abstracted view of the entire
   network topology containing IS-IS.  As such, this model is available
   via the NBI of SDN controllers.

2.2.  Relationship with Digital Map

   As described in [I-D.draft-havel-opsawg-digital-map], the Digital Map
   provides the core multi-layer topology model and data for the digital
   twin and connects them to the other digital twin models and data.

   The Digital Map Modelling defines the core topological entities,
   their role in the network, core properties, and relationships both
   inside each layer and between the layers.

   The Digital Map Model is a basic topological model that is linked to
   other functional parts of the digital twin and connects them all:
   configuration, maintenance, assurance (KPIs, status, health,
   symptoms), Traffic Engineering (TE), different behaviors and actions,
   simulation, emulation, mathematical abstractions, AI algorithms, etc.







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   As such the IGP topology of the Digital Map (in this case, IS-IS) is
   just one of the layers of the Digital Map, for specific user (the
   network operator in charge of the IGP) for specific IGP use cases as
   described before.

3.  Use of IETF-Topology for Representing an IP/MPLS network domain

   IP/MPLS Networks can contain multiple domain IGP domains.  We can
   define an IGP domain as the collection of nodes and links that
   participate in the same IGP process.  The topology information of a
   domain can be structured according to ietf-network-topology data
   model [RFC8345].  For example, if BGP-LS is used to collect the
   information, the nodes and links that are announced with the same
   combination of AS number / domain ID are considered to belong to the
   same domain.

   If a node and/or layer termination point participates in more than
   one IGP it will be present in multiple IGP domain networks.

   The ietf-network instance MUST include the following properties to
   indicate it is a domain running an IGP instance:

   A network-id that uniquely identifies such domain in the network.
   The "network-types" property should include the l3t:l3-unicast-
   topology, to indicate it is a network in which the nodes are capable
   of forwarding unicast packet.  Also, this draft proposed to add a new
   property, "isis-topology", to indicate the topology being represented
   is running the IS-IS IGP process.

   Also, should the topology include information such as bandwidth,
   delay information or color, it must include tet:te-topology.  To
   include delay and bandwdith performance measurements , MUST include
   tet-pkt:te-packet under the previous property The supporting-network
   property can include the network-id of a base layer-3 network.  The
   node property should include the list of nodes as described below.
   The ietf-network-topology:link MUST be present, with one link per
   each IP adjacency (one link for each direction of the adjancency).

4.  YANG Data Model for IS-IS Topology

   The abstract (base) network data model is defined in the "ietf-
   network" and "ietf-network-topology" modules of [RFC8345].  The L3
   topology module is defined in the "ietf-l3-unicast-topology" module
   of [RFC8346].  The ietf-l3-isis-topology builds on the data models
   defined in [RFC8345] and [RFC8346], augmenting the nodes with IS-IS
   information.





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   There is a set of parameters and augmentations that are included at
   the node level.  Each parameter and description are detailed
   following:

   *  Network-types: Its presence identifies the IS-IS topology type.
      Thus, the network type MUST be isis-topology.

   *  IS-IS timer attributes: Identifies the node timer attributes
      configured in the network element.  They are LSP lifetime and the
      LSP refresh interval.

   *  IS-IS status: contains the IS-IS status attributes (level, area-
      address and neighbours).

   The following figure is based on the Figure 1 from [RFC8346], where
   the example-ospf-topology is replaced with ietf-l3-isis-topology and
   where arrows show how the modules augment each other.

                         +-----------------------------+
                         |  +-----------------------+  |
                         |  |      ietf-network     |  |
                         |  +----------^------------+  |
                         |             |               |
                         |  +-----------------------+  |
                         |  | ietf-network-topology |  |
                         |  +----------+------------+  |
                         +-------------^---------------+
                                       |
                                       |
                          +------------^-------------+
                          | ietf-l3-unicast-topology |
                          +------------^-------------+
                                       |
                                       |
                           +-----------^-----------+
                           | ietf-l3-isis-topology |
                           +-----------------------+

                 Figure 1: IS-IS Topology module structure

   There are some limitations in the [RFC8345] that are explained in
   more detail in [I-D.draft-havel-opsawg-digital-map].  The current
   version of the ietf-l3-isis-topology module is based on the current
   version of [RFC8345].  The following will be addressed when [RFC8345]
   is extended to support the identified limitations:

   *  Both IS-IS domain and IS-IS areas could be modelled as networks




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   *  The IS-IS Areas will be connected via IS-IS links

   *  IS-IS nodes could belong to multiple IS-IS networks

   There is a set of parameters and augmentations that are included at
   the network level.

   *  Network-types: Its presence identifies the IS-IS topology type.
      Thus, the network type MUST be isis-topology.

   There is a set of parameters and augmentations that are included at
   the node level.  Each parameter and description are detailed
   following:

   *  IS-IS node core attributes: contains the IS-IS core attributes
      (system-id, level, area-address).

   *  IS-IS timer attributes: Identifies the node timer attributes
      configured in the network element.  They are LSP lifetime and the
      LSP refresh interval.

   There is a set of parameters and augmentations that are included at
   the link level.  Each parameter and description are detailed
   following:

   *  IS-IS link level.  The level must be the same as the termination
      points at each end for Level 1 and Level 2 interfaces.  There may
      be 2 links between the Level1-2 IS-IS interfaces, one for Level 1
      adjacency and one for Level 2 adjacency.

   *  IS-IS link metric.  Added on top of metric1 and metric2 of the l3-
      link-attributes

   There is a set of parameters and augmentations are included at the
   termination point level.  Each parameter is listed as follows:

   *  Interface-type: point-to point or braodcast

   *  Level.  The level must be the same as for the node, except when
      node is Level 1-2 and the interfaces can only be Level 1 or Level
      2.

   *  Passive mode

5.  IS-IS Topology Tree Diagram

   Figure 2 below shows the tree diagram of the YANG data model defined
   in module ietf-l3-isis-topology.yang (Figure 3).



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module: ietf-l3-isis-topology

  augment /nw:networks/nw:network/nw:network-types:
    +--rw isis-topology!
  augment /nw:networks/nw:network/nw:node/l3t:l3-node-attributes:
    +--rw isis-node-attributes
       +--rw system-id?              ietf-isis:system-id
       +--rw level?                  ietf-isis:level
       +--rw area-address*           ietf-isis:area-address
       +--rw lsp-lifetime?           uint16
       +--rw lsp-refresh-interval?   uint16
    +--rw isis-timer-attributes
    |  +--rw lsp-lifetime?           uint16
    |  +--rw lsp-refresh-interval?   uint16
    +--rw isis-status
       +--rw level?          ietf-isis:level
       +--rw area-address*   ietf-isis:area-address
       +--rw system-id?      ietf-isis:system-id
       +--ro neighbors*      inet:ip-address
  augment /nw:networks/nw:network/nt:link/l3t:l3-link-attributes:
    +--rw isis-termination-point-attributes
       +--rw interface-type?   ietf-isis:interface-type
       +--rw level?            ietf-isis:level
       +--rw metric?           uint32
       +--rw is-passive?       boolean
  augment /nw:networks/nw:network/nw:node/nt:termination-point/l3t:l3-termination-point-attributes:
    +--rw isis-termination-point-attributes
       +--rw interface-type?   ietf-isis:interface-type
       +--rw level?            ietf-isis:level
       +--rw metric?           uint32
       +--rw is-passive?       boolean

                Figure 2: IS-IS Topology tree diagram

6.  YANG Model for IS-IS topology

   This module imports types from [RFC8343] and [RFC8345].  Following
   the YANG model is presented.

   <CODE BEGINS> file "ietf-l3-isis-topology@2023-10-23.yang"
   module ietf-l3-isis-topology {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-l3-isis-topology";
     prefix "isisnt";

     import ietf-network {
       prefix "nw";



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       reference
         "RFC 8345: A YANG Data Model for Network Topologies";
     }

     import ietf-network-topology {
       prefix "nt";
       reference
         "RFC 8345: A YANG Data Model for Network Topologies";
     }

     import ietf-l3-unicast-topology {
       prefix "l3t";
       reference
         "RFC 8346: A YANG Data Model for Layer 3 Topologies";
     }

     import ietf-isis {
       prefix "ietf-isis";
       reference
         "RFC 9130: YANG Data Model for the IS-IS Protocols";
     }

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

     organization
       "IETF OPSA (Operations and Management Area) Working Group";
     contact
       "WG Web:  <https://datatracker.ietf.org/wg/opsawg/>
       WG List:  <mailto:opsawg@ietf.org>

       Editor:   Oscar Gonzalez de Dios
                 <mailto:oscar.gonzalezdedios@telefonica.com>
       Editor:   Samier Barguil
                 <mailto:samier.barguil_giraldo@nokia.com>
       Editor:   Victor Lopez
                 <mailto:victor.lopez@nokia.com>
       Editor:   Benoit Claise
                 <mailto:benoit.claise@huwaei.com>";
     description
       "This module defines a model for Layer 3 ISIS
        topologies.

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



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        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.";

     revision 2022-09-21 {
       description
         "Initial version";
       reference
         "RFC XXXX: A YANG Data Model for Intermediate System to
          Intermediate System (ISIS) Topology";
     }

     grouping isis-topology-type {
       description "Identifies the topology type to be ISIS.";
       container isis-topology {
         presence "indicates ISIS topology";
         description
           "The presence of the container node indicates ISIS
           topology";
       }
     }

     grouping isis-link-attributes {
        description "Identifies the IS-IS link attributes.";
        container isis-link-attributes {
        leaf metric {
         type uint32 {
            range "0 .. 16777215";
          }
         description
           "This type defines wide style format of IS-IS metric.";
        }
        leaf level {
         type ietf-isis:level;
         description
           "Level of an IS-IS node - can be level-1,
           level-2 or level-all.";
       }
       }
     }




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     grouping isis-node-attributes {
       description "isis node scope attributes";
       container isis-timer-attributes {
         description
           "Contains node timer attributes";
         uses ietf-isis:lsp-parameters;
       }
       container isis-node-attributes {
         leaf system-id {
             type ietf-isis:system-id;
             description
               "System-id of the node.";
           }
         leaf level {
             type ietf-isis:level;
             description
               "Level of an IS-IS node - can be level-1,
               level-2 or level-all.";
           }
         leaf-list area-address {
             type ietf-isis:area-address;
             description
               "List of areas supported by the protocol instance.";
           }
         leaf lsp-lifetime {
             type uint16 {
                range "1..65535";
              }
             units "seconds";
             description
               "Lifetime of the router's LSPs in seconds.";
           }
         leaf lsp-refresh-interval {
             type uint16 {
                range "1..65535";
              }
             units "seconds";
             description
               "Refresh interval of the router's LSPs in seconds.";
           }
         }
     }

   grouping isis-termination-point-attributes {
       description "IS-IS termination point scope attributes";
       container isis-termination-point-attributes {
          description
         "Indicates the termination point from the



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         which the IS-IS is configured. A termination
         point can be a physical port, an interface, etc.";

       leaf interface-type {
         type ietf-isis:interface-type;
         description
           "Type of adjacency (broadcast or point-to-point) to be established
           for the interface.
           This dictates the type of hello messages that are used.";
       }

       leaf level {
         type ietf-isis:level;
         description
           "Level of an IS-IS node - can be level-1,
           level-2 or level-all.";
       }

       leaf is-passive{
         type boolean;
         description
           "Indicates whether the interface is in passive mode (IS-IS
           not running but network is advertised).";
         }
       }
     }

     augment "/nw:networks/nw:network/nw:network-types" {
       description
         "Introduces new network type for L3 Unicast topology";
       uses isis-topology-type;
     }

     augment "/nw:networks/nw:network/nw:node/l3t:l3-node-attributes" {
       when "/nw:networks/nw:network/nw:network-types/isisnt:isis-topology" {
         description
           "Augmentation parameters apply only for networks with
           isis topology";
       }
       description
         "isis node-level attributes ";
       uses isis-node-attributes;
     }

     augment "/nw:networks/nw:network/nt:link/l3t:l3-link-attributes" {
       when "/nw:networks/nw:network/nw:network-types/isisnt:isis-topology" {
         description
           "Augmentation parameters apply only for networks with



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           IS-IS topology";
       }
       description
         "Augments topology link configuration";
       uses isis-link-attributes;
     }



     augment "/nw:networks/nw:network/nw:node/nt:termination-point"+
     "/l3t:l3-termination-point-attributes" {
       when "/nw:networks/nw:network/nw:network-types/isisnt:isis-topology" {
         description
           "Augmentation parameters apply only for networks with
           IS-IS topology";
       }
       description
         "Augments topology termination point configuration";
       uses isis-termination-point-attributes;
     }
   }
   <CODE ENDS>

                    Figure 3: IS-IS Topology YANG module

7.  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 Network Configuration Access Control Model (NACM) [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.

   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.





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8.  IANA Considerations

   This document registers the following namespace URIs in the IETF XML
   registry [RFC3688]:

   --------------------------------------------------------------------
   URI: urn:ietf:params:xml:ns:yang:ietf-l3-isis-topology
   Registrant Contact: The IESG.
   XML: N/A, the requested URI is an XML namespace.
   --------------------------------------------------------------------

   This document registers the following YANG module in the YANG Module
   Names registry [RFC6020]:

   --------------------------------------------------------------------
   name:         ietf-l3-isis-topology
   namespace:    urn:ietf:params:xml:ns:yang:ietf-l3-isis-topology
   maintained by IANA: N
   prefix:       ietf-l3-isis-topology
   reference:    RFC XXXX
   --------------------------------------------------------------------

9.  Normative References

   [I-D.draft-havel-opsawg-digital-map]
              Havel, O., Claise, B., de Dios, O. G., Elhassany, A.,
              Graf, T., and M. Boucadair, "Modeling the Digital Map
              based on RFC 8345: Sharing Experience and Perspectives",
              Work in Progress, Internet-Draft, draft-havel-opsawg-
              digital-map-01, 23 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-havel-opsawg-
              digital-map-01>.

   [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/rfc/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/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/rfc/rfc6020>.





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

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

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

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

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

   [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/rfc/rfc8340>.

   [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/rfc/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/rfc/rfc8342>.

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

   [RFC8345]  Clemm, A., Medved, J., Varga, R., Bahadur, N.,
              Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
              Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
              2018, <https://www.rfc-editor.org/rfc/rfc8345>.

   [RFC8346]  Clemm, A., Medved, J., Varga, R., Liu, X.,
              Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model
              for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346,
              March 2018, <https://www.rfc-editor.org/rfc/rfc8346>.




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   [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/rfc/rfc8446>.

   [RFC8795]  Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
              O. Gonzalez de Dios, "YANG Data Model for Traffic
              Engineering (TE) Topologies", RFC 8795,
              DOI 10.17487/RFC8795, August 2020,
              <https://www.rfc-editor.org/rfc/rfc8795>.

   [RFC9130]  Litkowski, S., Ed., Yeung, D., Lindem, A., Zhang, J., and
              L. Lhotka, "YANG Data Model for the IS-IS Protocol",
              RFC 9130, DOI 10.17487/RFC9130, October 2022,
              <https://www.rfc-editor.org/rfc/rfc9130>.

Appendix A.  Implementation Status

   Note to the RFC-Editor: Please remove this section before publishing.

A.1.  Implementation Status in Telefonica Group

   The Yang based topology model proposed in this draft is being used
   today in one of the Telefonica operations to export the Multi-vendor
   IP/MPLS topology based on multiple IS-IS domains to several Operation
   Support System tools for visualization, capacity planning and
   simulation.  A commercial controller has implemented the exposure of
   the information.  It is one of the building blocks to expose the
   network capabilities, together with other models which cover the
   inventory and service provisioning in a vendor-agnostic fashion.

A.2.  Huawei Digital Map PoC Status

   As mentioned in [I-D.draft-havel-opsawg-digital-map], a Digital Map
   PoC with a real lab has been built, based on multi- vendor devices,
   with [RFC8345] as the base YANG module for the topology building
   blocks.  This PoC successfully modelled IS-IS routing (among other
   technologies and layers), but it needs to be further aligned with
   this latest developments in this draft.

A.3.  Implementation Status in E-lighthouse Network Solutions

   E-lighthouse Network Solutions (https://e-lighthouse.com/)
   implementation is consuming the IS-IS network topology information
   exported by a commercial controller, using the Yang model proposed in
   this draft.  It is able to simulate the network behavior under
   different changes, covering the what-if, failure analysis,
   dimensioning and other use cases mentioned in this draft.




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Acknowledgments

   The authors would like to thank Pierre Francois for the review and
   suggestions the document.

   This work is partially supported by the European Commission under
   grant agreement No. 101092766 (ALLEGRO Project) and Horizon 2020
   Secured autonomic traffic management for a Tera of SDN flows
   (Teraflow) project (grant agreement number 101015857).

Contributors

   Olga Havel
   Huawei
   Email: olga.havel@huawei.com


   Pablo Pavon
   Universidad Politecnica de Cartegena
   Email: pablo.pavon@upct.es


Authors' Addresses

   Oscar González de Dios
   Telefonica
   Email: oscar.gonzalezdedios@telefonica.com


   Samier Barguil Giraldo
   Nokia
   Email: samier.barguil_giraldo@nokia.com


   Victor Lopez
   Nokia
   Email: victor.lopez@nokia.com


   Daniele Ceccarelli
   Cisco
   Email: dceccare@cisco.com


   Benoit Claise
   Huawei
   Email: benoit.claise@huawei.com




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