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Versions: (draft-busizheng-teas-mpls-tp-yang) 00

TEAS Working Group                                           Italo Busi
Internet Draft                                            Haomian Zheng
Intended status: Standard Track                                  Huawei
                                                              Aihua Guo
                                                              Futurewei
                                                             Xufeng Liu
                                                         Volta Networks


Expires: January 2021                                     July 13, 2020



                  A YANG Data Model for MPLS-TE Topology
               draft-busizheng-teas-yang-te-mpls-topology-00


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
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   This Internet-Draft will expire on January 13, 2021.

Copyright Notice

   Copyright (c) 2020 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




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   (http://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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Abstract

   This document describes a YANG data model for Multi-Protocol Label
   Switching (MPLS) with Traffic Engineering (MPLS-TE) networks.

Table of Contents


   1. Introduction...................................................2
      1.1. Tree Diagram..............................................3
      1.2. Prefixes in Data Node Names...............................3
   2. MPLS-TE Types Overview.........................................3
   3. MPLS-TE Topology Model Overview................................4
      3.1. TE Label Augmentations....................................6
      3.2. MPLS-TP Topology..........................................6
   4. YANG model for common MPLS-TE Types............................7
   5. YANG model for MPLS-TE Topology...............................12
      5.1. YANG Tree................................................12
      5.2. YANG Code................................................16
   6. Security Considerations.......................................27
   7. IANA Considerations...........................................27
   8. References....................................................27
      8.1. Normative References.....................................27
      8.2. Informative References...................................28
   Acknowledgments..................................................28
   Authors' Addresses...............................................29

1. Introduction

   This document describes a YANG data model for Multi-Protocol Label
   Switching (MPLS) with Traffic Engineering (MPLS-TE) networks.

   This document also defines a collection of common data types and
   groupings in YANG data modeling language for MPLS-TE networks.  These
   derived common types and groupings are intended to be imported by the
   MPLS-TE topology model, defined in this document, as well as by the
   MPLS-TE tunnel model, defined in [TE-MPLS].




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   Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a
   profile of the MPLS protocol that is used in packet switched
   transport networks and operated in a similar manner to other existing
   transport technologies (e.g., OTN), as described in RFC5921. The YANG
   model defined in this document can also be for MPLS-TP networks.

1.1. Tree Diagram

   A simplified graphical representation of the data model is used in
   section 5.1 of this this document.  The meaning of the symbols in
   these diagrams is defined in [RFC8340].

1.2. Prefixes 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 Table 1.

   +---------------+-------------------------+-----------------------+
   | Prefix        | YANG module             | Reference             |
   +---------------+-------------------------+-----------------------+
   | rt-types      | ietf-routing-types      | [RFC8294]             |
   | tet           | ietf-te-topology        | [TE-Topology]         |
   | tet-pkt       | ietf-te-topology-packet | [L3-TE-Topology]      |
   | mte-types     | ietf-mpls-te-types      | This document         |
   | tet-mpls      | ietf-te-mpls-topology   | This document         |
   +---------------+-------------------------+-----------------------+


                Table 1: Prefixes and corresponding YANG modules

2. MPLS-TE Types Overview

   The module ietf-mpls-te-types contains the following YANG reusable
   types and groupings:

   bandwidth-profile-type:

   This identity defines various bandwidth profiles specified by IETF
   and other organizations that may be used to limit bandwidth
   utilization of MPLS-TE LSPs.

   load-balancing-type

   This identify defines the types of load-balancing algorithms used on
   bundled MPLS-TE link.



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   te-packet-path-bandwidth

   This grouping defines the path bandwidth information and could be
   used in MPLS-TE topology model for the representation of MPLS-TE LSP
   bandwidth. All the path and LSP bandwidth related sections in generic
   module, [RFC8776], need to be augmented with this grouping for the
   usage of MPLS-TE.  This grouping is also applicable to set up the
   MPLS-TE tunnel.

   te-packet-link-bandwidth

   This grouping defines the link bandwidth information and could be
   used in MPLS-TE topology model for link bandwidth representation.
   All the link bandwidth related sections in generic module, [RFC8776],
   need to be augmented with this grouping for the usage of MPLS_TE.

   te-mpls-label-hop

   This grouping is used for the augmentation of TE label for MPLS_TE
   path.

3. MPLS-TE Topology Model Overview

   The MPLS-TE technology specific topology model augments the ietf-te-
   topology-packet YANG module, defined in [L3-TE-Topology], which in
   turns augment the generic ietf-te-topology YANG module, defined in
   [TE-Topology].






















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                     +------------------+    o: augment
        TE generic   | ietf-te-topology |
                     +------------------+
                               o
                               |
                               |
                               |
                  +-------------------------+
        Packet TE | ietf-te-topology-packet |
                  +-------------------------+
                               o
                               |
                               |
                               |
                   +-----------------------+
        MPLS-TE    | ietf-te-mpls-topology |
                   +-----------------------+

    Figure 1 - Relationship between MPLS-TE, Packet-TE and TE topology
                                    models

   Given the guidance for augmentation in [TE-Topology], the following
   technology-specific augmentations need to be provided:

   - A network-type to indicate that the TE topology is an MPLS-TE
     Topology, as follow:

    augment /nw:networks/nw:network/nw:network-types/tet:te-topology
              /tet-pkt:packet:
      +--rw mpls-topology!

   - TE Bandwidth Augmentations for paths and LSPs:

         +--:(packet)
            +--rw bandwidth-profile-name?   string
            +--rw bandwidth-profile-type?   identityref
            +--rw CIR?                      uint64
            +--rw EIR?                      uint64
            +--rw CBS?                      uint64
            +--rw EBS?                      uint64

   - TE Bandwidth Augmentations for links:

      +--:(packet)
         +--rw packet-bandwidth?   bandwidth-kbps




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   - TE Label Augmentations as described in section 3.2;

3.1. TE Label Augmentations

   In MPLS-TE, the label allocation is done by NE, information about
   label values availability is not necessary to be provided to the
   controller. Moreover, MPLS-TE tunnels are currently established
   within a single domain.

   Therefore this document does not define any MPLS-TE
   technology-specific augmentations, of the TE Topology model, for the
   TE label since no TE label related attributes should be instantiated
   for MPLS-TE Topologies.

   Open issue: shall this module allows the setup of MPLS-TE
   multi-domain tunnels?

3.2. MPLS-TP Topology

   Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a
   profile of the MPLS protocol that is used in packet switched
   transport networks and operated in a similar manner to other existing
   transport technologies (e.g., OTN), as described in [RFC5921].

   Therefore YANG model defined in this document can also be applicable
   for MPLS-TP networks.

   However, as described in [RFC5921], MPLS-TP networks support
   bidirectional LSPs and require no ECMP and no PHP. When reporting the
   topology for an MPLS-TP network, additional information is required
   to indicate whether the network support these MPLS-TP
   characteristics.

   It is worth noting that [TE-Topology] is already capable to model TE
   topologies supporting either unidirectional or bidirectional LSPs:
   all bidirectional TE links can support bidirectional LSPs and all the
   links can support unidirectional LSPs and it is always possible to
   associated unidirectional LSPs as long as they belong to the same
   tunnel.

   When setting up bidirectional LSPs (e.g., MPLS-TP LSPs) only
   bidirectional TE Links are selected by path computation.

   In order to allow reporting that ECMP is not affecting forwarding the
   packets of a given LSP, the load-balancing-type attribute reports




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   whether a LAG or TE Bundled Link performs load-balancing on a
   per-flow or per-top-label:

       augment /nw:networks/nw:network/nt:link/tet:te:
         +--rw load-balancing-type?   mte-types:load-balancing-type

   When setting up LSPs which do not requires ECMP (e.g., MPLS-TP LSPs)
   only Links that are not part of a LAG or TE Bundle or that performs
   per-top-label load balancing are selected by path computation.

   It is assumed that almost all the MPLS-TE nodes are capable to
   support Ultimate Hop Popping (UHP). However, if some interfaces are
   not able to support UHP, they can report it in the MPLS-TE topology:

       augment /nw:networks/nw:network/nw:node/nt:termination-point
                 /tet:te:
         +--ro uhp-incapable?   empty

   When setting up LSPs which do not requires PHP (e.g., MPLS-TP LSPs)
   only the interfaces (LTPs) which are capable to support UHP in the
   destination node are selected by path computation.

4. YANG model for common MPLS-TE Types

   <CODE BEGINS>file "ietf-mpls-te-types@2020-07-13.yang"
   module ietf-mpls-te-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-te-types";

     prefix "mte-types";

     import ietf-routing-types {
       prefix "rt-types";

     }

     import ietf-te-packet-types {
       prefix "te-packet-types";
       reference
         "RFC 8776: Common YANG Data Types for Traffic Engineering";
     }

     organization
       "Internet Engineering Task Force (IETF) TEAS WG";


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

        Editor: Italo Busi
          <mailto:italo.busi@huawei.com>

        Editor: Haomian Zheng
          <mailto:zhenghaomian@huawei.com>

        Editor: Aihua Guo
          <mailto:aihuaguo.ietf@gmail.com>

        Editor: Xufeng Liu
          <mailto:xufeng.liu.ietf@gmail.com>";

     description
       "This module defines technology-specific MPLS-TE types
        data model.

        Copyright (c) 2020 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
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX; see
        the RFC itself for full legal notices.";

     revision 2020-07-13 {
       description
         "Initial Version";
       reference
         "draft-busizheng-teas-yang-te-mpls-topology";
     }

   /*


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    * Identities (to be moved to te-packet-types?)
    */

     identity bandwidth-profile-type {
       description
         "Bandwidth Profile Types";
     }

     identity mef-10-bwp {
       base bandwidth-profile-type;
       description
         "MEF 10 Bandwidth Profile";
     }

     identity rfc-2697-bwp {
       base bandwidth-profile-type;
       description
         "RFC 2697 Bandwidth Profile";
     }

     identity rfc-2698-bwp {
       base bandwidth-profile-type;
       description
         "RFC 2698 Bandwidth Profile";
     }

     identity rfc-4115-bwp {
       base bandwidth-profile-type;
       description
         "RFC 4115 Bandwidth Profile";
     }

   /*
    * Type Definitions (MPLS-TE)
    */

     typedef load-balancing-type {
       type enumeration {
         enum per-flow {
           description
             "The load-balancing algorithm ensures that packets


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              characterized as the same flow (e.g. based on IP 5-tuple)
              that egress on a LAG or a bundled TE link are forwarded
              on the same component link.

              Packets for different flows within the same LSP can be
              forwarded on different component links.";
         }
         enum per-top-label {
           description
             "The load-balancing algorithm ensures incoming MPLS
              packets with the same top MPLS label and that egress on
              a on a LAG or bundled TE link are forwarded on the same
              component link.



              Packets for different flows within the same LSP are
              forwarded on the same component link.";
         }
       }
       description
         "The type of load balancing used on bundled links.";
     }  // typedef load-balancing-type

   /*
    * Groupings (to be moved to te-packet-types?)
    */

     grouping te-packet-path-bandwidth {
       description
         "Path bandwidth for Packet. ";
       leaf bandwidth-profile-name{
         type string;
         description "Name of Bandwidth Profile.";
       }
       leaf bandwidth-profile-type {
         type identityref {
           base bandwidth-profile-type;
         }
         description "Type of Bandwidth Profile.";
       }


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       leaf CIR {
         type uint64;
           description
             "Committed Information Rate in Kbps";
       }

       leaf EIR {
         type uint64;
         /*
           Need to indicate that EIR is not supported by RFC 2697

           must
               '../bw-profile-type = "etht-types:mef-10-bwp" or ' +
               '../bw-profile-type = "etht-types:rfc-2698-bwp" or ' +
               '../bw-profile-type = "etht-types:rfc-4115-bwp"'

           must
               '../bw-profile-type != "etht-types:rfc-2697-bwp"'
         */
         description
           "Excess Information Rate in Kbps
           In case of RFC 2698, PIR = CIR + EIR";
       }

       leaf CBS {
         type uint64;
         description
           "Committed Burst Size in in KBytes";
       }

       leaf EBS {
         type uint64;
         description
           "Excess Burst Size in KBytes.
             In case of RFC 2698, PBS = CBS + EBS";
       }
     }

     grouping te-packet-link-bandwidth {
       description


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         "Link Bandwidth for Packet. ";
       leaf packet-bandwidth {
         type te-packet-types:bandwidth-kbps;
         description
           "Available bandwith value expressed in kilobits per
            second";
       }
     }

   /*
    * Groupings (MPLS-TE)
    */

     grouping te-mpls-label-hop {
       description
         "MPLS-TE Label Hop.";

       leaf mpls-label {
         type rt-types:mpls-label;
         description
           "MPLS Label.";
       }
     }  // grouping te-mpls-label-hop
   }
   <CODE ENDS>

                   Figure 2 - MPLS-TE types YANG module

5. YANG model for MPLS-TE Topology

5.1. YANG Tree

   Figure 3 below shows the tree diagram of the YANG model defined in
   module ietf-te-mpls-topology.yang.


   module: ietf-te-mpls-topology
     augment /nw:networks/nw:network/nw:node/nt:termination-point/tet:te
               /tet:interface-switching-capability/tet:max-lsp-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw bandwidth-profile-name?   string


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          +--rw bandwidth-profile-type?   identityref
          +--rw CIR?                      uint64
          +--rw EIR?                      uint64
          +--rw CBS?                      uint64
          +--rw EBS?                      uint64
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:te-node-attributes/tet:connectivity-matrices
               /tet:path-constraints/tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:te-node-attributes/tet:connectivity-matrices
               /tet:connectivity-matrix/tet:path-constraints
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:information-source-entry/tet:connectivity-matrices
               /tet:path-constraints/tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:information-source-entry/tet:connectivity-matrices
               /tet:connectivity-matrix/tet:path-constraints
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:tunnel-termination-point/tet:client-layer-adaptation
               /tet:switching-capability/tet:te-bandwidth
               /tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:tunnel-termination-point
               /tet:local-link-connectivities/tet:path-constraints
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:node/tet:te
               /tet:tunnel-termination-point


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               /tet:local-link-connectivities
               /tet:local-link-connectivity/tet:path-constraints
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:te-link-attributes
               /tet:interface-switching-capability/tet:max-lsp-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw bandwidth-profile-name?   string
          +--rw bandwidth-profile-type?   identityref
          +--rw CIR?                      uint64
          +--rw EIR?                      uint64
          +--rw CBS?                      uint64
          +--rw EBS?                      uint64
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:te-link-attributes/tet:max-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:te-link-attributes/tet:max-resv-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:te-link-attributes/tet:unreserved-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:information-source-entry
               /tet:interface-switching-capability/tet:max-lsp-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro bandwidth-profile-name?   string
          +--ro bandwidth-profile-type?   identityref
          +--ro CIR?                      uint64
          +--ro EIR?                      uint64
          +--ro CBS?                      uint64


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          +--ro EBS?                      uint64
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:information-source-entry/tet:max-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:information-source-entry/tet:max-resv-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nt:link/tet:te
               /tet:information-source-entry/tet:unreserved-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--ro packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/tet:te/tet:templates/tet:link-template
               /tet:te-link-attributes
               /tet:interface-switching-capability/tet:max-lsp-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw bandwidth-profile-name?   string
          +--rw bandwidth-profile-type?   identityref
          +--rw CIR?                      uint64
          +--rw EIR?                      uint64
          +--rw CBS?                      uint64
          +--rw EBS?                      uint64
     augment /nw:networks/tet:te/tet:templates/tet:link-template
               /tet:te-link-attributes/tet:max-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/tet:te/tet:templates/tet:link-template
               /tet:te-link-attributes/tet:max-resv-link-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)
          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/tet:te/tet:templates/tet:link-template
               /tet:te-link-attributes/tet:unreserved-bandwidth
               /tet:te-bandwidth/tet:technology:
       +--:(packet)


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          +--rw packet-bandwidth?   te-packet-types:bandwidth-kbps
     augment /nw:networks/nw:network/nw:network-types/tet:te-topology
               /tet-pkt:packet:
       +--rw mpls-topology!
     augment /nw:networks/nw:network/nt:link/tet:te:
       +--rw load-balancing-type?   mte-types:load-balancing-type
     augment /nw:networks/nw:network/nw:node/nt:termination-point
               /tet:te:
       +--ro uhp-incapable?   empty

                   Figure 3 - MPLS-TE topology YANG tree

5.2. YANG Code

   <CODE BEGINS>file "ietf-te-mpls-topology@2020-07-13.yang"
   module ietf-te-mpls-topology {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-te-mpls-topology";

     prefix "tet-mpls";

     import ietf-network {
       prefix "nw";
     }

     import ietf-network-topology {
       prefix "nt";
     }

     import ietf-te-topology {
       prefix "tet";
     }

     import ietf-te-topology-packet {
       prefix "tet-pkt";
     }

     import ietf-mpls-te-types {
       prefix "mte-types";
     }




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     organization
       "Internet Engineering Task Force (IETF) TEAS WG";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/teas/>
        WG List:  <mailto:teas@ietf.org>

        Editor: Italo Busi
          <mailto:italo.busi@huawei.com>

        Editor: Haomian Zheng
          <mailto:zhenghaomian@huawei.com>

        Editor: Aihua Guo
          <mailto:aihuaguo.ietf@gmail.com>

        Editor: Xufeng Liu
          <mailto:xufeng.liu.ietf@gmail.com>";

     description
       "This module defines technology-specific MPLS-TE topology
        data model.

        Copyright (c) 2020 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
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX; see
        the RFC itself for full legal notices.";

     revision 2020-07-13 {
       description
         "Initial Version";
       reference
         "draft-busizheng-teas-yang-te-mpls-topology";
     }


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     /*
      * Augment TE bandwidth (to be moved to te-topology-packet?)
      */

     augment "/nw:networks/nw:network/nw:node/nt:termination-point/"
           + "tet:te/"
           + "tet:interface-switching-capability/tet:max-lsp-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum LSP TE bandwidth for the link termination
          point (LTP).";
       case packet {
         uses mte-types:te-packet-path-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:te-node-attributes/tet:connectivity-matrices/"
           + "tet:path-constraints/tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints of the TE node
          connectivity matrices.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"


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           + "tet:te-node-attributes/tet:connectivity-matrices/"
           + "tet:connectivity-matrix/"
           + "tet:path-constraints/tet:te-bandwidth/tet:technology" {
       when "../../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints of the
          connectivity matrix entry.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:information-source-entry/tet:connectivity-matrices/"
           + "tet:path-constraints/tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints of the TE node
          connectivity matrices information source.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:information-source-entry/tet:connectivity-matrices/"
           + "tet:connectivity-matrix/"
           + "tet:path-constraints/tet:te-bandwidth/tet:technology" {
       when "../../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description


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           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints of the
          connectivity matrix entry information source";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:tunnel-termination-point/"
           + "tet:client-layer-adaptation/tet:switching-capability/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment client TE bandwidth of the tunnel termination point
          (TTP)";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:tunnel-termination-point/"
           + "tet:local-link-connectivities/tet:path-constraints/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints for the TTP


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          Local Link Connectivities.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nw:node/tet:te/"
           + "tet:tunnel-termination-point/"
           + "tet:local-link-connectivities/"
           + "tet:local-link-connectivity/tet:path-constraints/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment TE bandwidth path constraints for the TTP
          Local Link Connectivity entry.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:te-link-attributes/"
           + "tet:interface-switching-capability/tet:max-lsp-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum LSP TE bandwidth for the TE link.";
       case packet {
         uses mte-types:te-packet-path-bandwidth;
       }
     }


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     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:te-link-attributes/"
           + "tet:max-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum TE bandwidth for the TE link";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:te-link-attributes/"
           + "tet:max-resv-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum reservable TE bandwidth for the TE link";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:te-link-attributes/"
           + "tet:unreserved-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {


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         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment unreserved TE bandwidth for the TE Link";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:information-source-entry/"
           + "tet:interface-switching-capability/"
           + "tet:max-lsp-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum LSP TE bandwidth for the TE link
          information source";
       case packet {
         uses mte-types:te-packet-path-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:information-source-entry/"
           + "tet:max-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description


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         "Augment maximum TE bandwidth for the TE link
          information source";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:information-source-entry/"
           + "tet:max-resv-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment maximum reservable TE bandwidth for the TE link
          information-source";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:information-source-entry/"
           + "tet:unreserved-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       when "../../../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet" {
         description
           "Augmentation parameters apply only for networks with
            Packet TE topology type.";
       }
       description
         "Augment unreserved TE bandwidth of the TE link
          information source";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }


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     }

     augment "/nw:networks/tet:te/tet:templates/"
           + "tet:link-template/tet:te-link-attributes/"
           + "tet:interface-switching-capability/"
           + "tet:max-lsp-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       description
         "Augment maximum LSP TE bandwidth of the TE link
          template";
       case packet {
         uses mte-types:te-packet-path-bandwidth;
       }
     }

     augment "/nw:networks/tet:te/tet:templates/"
           + "tet:link-template/tet:te-link-attributes/"
           + "tet:max-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       description
         "Augment maximum TE bandwidth the TE link template";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/tet:te/tet:templates/"
           + "tet:link-template/tet:te-link-attributes/"
           + "tet:max-resv-link-bandwidth/"
           + "tet:te-bandwidth/tet:technology" {
       description
         "Augment maximum reservable TE bandwidth for the TE link
          template.";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     augment "/nw:networks/tet:te/tet:templates/"
           + "tet:link-template/tet:te-link-attributes/"
           + "tet:unreserved-bandwidth/"


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           + "tet:te-bandwidth/tet:technology" {
       description
         "Augment unreserved TE bandwidth the TE link template";
       case packet {
         uses mte-types:te-packet-link-bandwidth;
       }
     }

     /*
      * Augmentations
      */

     augment "/nw:networks/nw:network/nw:network-types/"
           + "tet:te-topology/tet-pkt:packet" {
       description
         "Augment network types to include MPLS-TE Topology Type";
       container mpls-topology {
         presence
           "Indicates an MPLS-TE Topology Type.";
         description
           "Its presence indicates an MPLS-TE Topology";
       }
     }

     augment "/nw:networks/nw:network/nt:link/tet:te" {
       when "../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet/tet-mpls:mpls-topology"  {
         description
           "Augment MPLS-TE Topology.";
       }
       description
         "Augment TE Link.";

       leaf load-balancing-type {
         type mte-types:load-balancing-type;
         default 'per-flow';
         description
           "Indicates the type of load-balancing (per-flow or per-LSP)
            performed by the bundled TE Link.

            This leaf is not present when the TE Link is not bundled.";


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       }  // leaf load-balancing-type
     }

     augment "/nw:networks/nw:network/nw:node/nt:termination-point/"
           + "tet:te" {
       when "../../../nw:network-types/tet:te-topology/"
          + "tet-pkt:packet/tet-mpls:mpls-topology" {
         description "Augment MPLS-TE Topology.";
       }
       description "Augment LTP.";

       leaf uhp-incapable {
         type empty;
         config false;
         description
           "When present, indicates that the LTP is not capable to
            support Ultimate Hop Popping (UHP).";
       }   // leaf uhp-incapable
     }
   }
   <CODE ENDS>

                  Figure 4 - MPLS-TE topology YANG module

6. Security Considerations

   To be added

7. IANA Considerations

   To be added

8. References

8.1. Normative References

   [RFC6991] J. Schoenwaelder, "Common YANG Data Types", RFC6991.

   [RFC8294] X. Liu, et. al., "Common YANG Data Types for the Routing
             Area", RFC8294.

   [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP
             215, RFC 8340, March 2018.



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   [RFC8776] Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
             "Common YANG Data Types for Traffic Engineering", RFC8776,
             June 2020.

   [TE-Topology] X. Liu, et. al., "YANG Data Model for TE Topologies",
             draft-ietf-teas-yang-te-topo, work in progress.

   [L3-TE-Topology] X. Liu, et. al., "YANG Data Model for Layer 3 TE
             Topologies", draft-ietf-teas-yang-l3-te-topo, work in
             progress.

8.2. Informative References

   [RFC5921] M. Bocci, et., al., "A Framework for MPLS in Transport
             Networks", RFC5921.

   [TE-MPLS] T. Saad, et. al., "A YANG Data Model for MPLS Traffic
             Engineering Tunnels", draft-ietf-teas-yang-te-mpls, work in
             progress.

Acknowledgments

   The authors would also like to thank Tarek Saad, Vishnu Pavan Beeram,
   Rakesh Gandhi, Xufeng Liu, Igor Bryskin for their input on how to
   support MPLS-TP features (bidirectional LSPs, no ECMP, no PHP) using
   a common MPLS-TE topology model.

   We thank Loa Andersson and Igor Bryskin for providing useful
   suggestions for this draft.

   This document was prepared using 2-Word-v2.0.template.dot.


















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Authors' Addresses

   Italo Busi
   Huawei Technologies
   Email: italo.busi@huawei.com

   Haomian Zheng
   Huawei Technologies
   Email: zhenghaomian@huawei.com

   Aihua Guo
   Futurewei Inc.
   Email: aihuaguo.ietf@gmail.com

   Xufeng Liu
   Volta Networks
   Email: xufeng.liu.ietf@gmail.com
































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