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Versions: (draft-liu-teas-yang-te-topo) 00 01 02 03 04 05 06 07 08 09 10 11 12 13

TEAS Working Group                                           Xufeng Liu
Internet Draft                                                    Jabil
Intended status: Standards Track                           Igor Bryskin
                                                    Huawei Technologies
                                                    Vishnu Pavan Beeram
                                                       Juniper Networks
                                                             Tarek Saad
                                                      Cisco Systems Inc
                                                          Himanshu Shah
                                                                  Ciena
                                                 Oscar Gonzalez De Dios
                                                             Telefonica

Expires: January 17, 2018                                 July 17, 2017


                     YANG Data Model for TE Topologies
                      draft-ietf-teas-yang-te-topo-12


Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on January 17, 2018.

Copyright Notice

   Copyright (c) 2017 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
   (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 defines a YANG data model for representing, retrieving
   and manipulating TE Topologies. The model serves as a base model that
   other technology specific TE Topology models can augment.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].


Table of Contents

   1. Introduction...................................................3
      1.1. Terminology...............................................4
      1.2. Tree Structure - Legend...................................4
      1.3. Prefixes in Data Node Names...............................5
   2. Characterizing TE Topologies...................................5
   3. Modeling Abstractions and Transformations......................7
      3.1. TE Topology...............................................7
      3.2. TE Node...................................................7
      3.3. TE Link...................................................8
      3.4. Transitional TE Link for Multi-Layer Topologies...........8
      3.5. TE Link Termination Point (LTP)...........................9
      3.6. TE Tunnel Termination Point (TTP)........................10
      3.7. TE Node Connectivity Matrix..............................10
      3.8. TTP Local Link Connectivity List (LLCL)..................10
      3.9. TE Path..................................................10
      3.10. TE Inter-Layer Lock.....................................11
      3.11. Underlay TE topology....................................12
      3.12. Overlay TE topology.....................................12
      3.13. Abstract TE topology....................................12
   4. Model Applicability...........................................13
      4.1. Native TE Topologies.....................................13
      4.2. Customized TE Topologies.................................15


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      4.3. Merging TE Topologies Provided by Multiple Providers.....18
      4.4. Dealing with Multiple Abstract TE Topologies Provided by the
      Same Provider.................................................21
   5. Modeling Considerations.......................................24
      5.1. Network topology building blocks.........................24
      5.2. Technology agnostic TE Topology model....................24
      5.3. Model Structure..........................................25
      5.4. Topology Identifiers.....................................26
      5.5. Generic TE Link Attributes...............................26
      5.6. Generic TE Node Attributes...............................27
      5.7. TED Information Sources..................................28
      5.8. Overlay/Underlay Relationship............................29
      5.9. Templates................................................30
      5.10. Scheduling Parameters...................................31
      5.11. Notifications...........................................31
   6. Tree Structure................................................32
   7. TE Topology Yang Module.......................................68
   8. Security Considerations......................................115
   9. IANA Considerations..........................................115
   10. References..................................................116
      10.1. Normative References...................................116
      10.2. Informative References.................................116
   11. Acknowledgments.............................................117
   Appendix A. Companion YANG Model for Non-NMDA Compliant
   Implementations.................................................118
      A.1. TE Topology State Yang Module...........................118
   Contributors....................................................125
   Authors' Addresses..............................................126

1. Introduction

   The Traffic Engineering Database (TED) is an essential component of
   Traffic Engineered (TE) systems that are based on MPLS-TE [RFC2702]
   and GMPLS [RFC3945]. The TED is a collection of all TE information
   about all TE nodes and TE links in the network. The TE Topology is a
   schematic arrangement of TE nodes and TE links present in a given
   TED. There could be one or more TE Topologies present in a given
   Traffic Engineered system. The TE Topology is the topology on which
   path computational algorithms are run to compute Traffic Engineered
   Paths (TE Paths).

   This document defines a YANG [RFC6020] data model for representing
   and manipulating TE Topologies. This model contains technology
   agnostic TE Topology building blocks that can be augmented and used
   by other technology-specific TE Topology models.




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1.1. Terminology

   TED: The Traffic Engineering Database is a collection of all TE
   information about all TE nodes and TE links in a given network.

   TE-Topology: The TE Topology is a schematic arrangement of TE nodes
   and TE links in a given TED. It forms the basis for a graph suitable
   for TE path computations.

   Native TE Topology: Native TE Topology is a topology that is native
   to a given provider network. Native TE topology could be discovered
   via various routing protocols and/or subscribe/publish techniques.
   This is the topology on which path computational algorithms are run
   to compute TE Paths.

   Customized TE Topology: Customized TE Topology is a custom topology
   that is produced by a provider for a given Client. This topology
   typically augments the Client's Native TE Topology. Path
   computational algorithms aren't typically run on the Customized TE
   Topology; they are run on the Client's augmented Native TE Topology.

1.2. Tree Structure - Legend

   A simplified graphical representation of the data model is presented
   in Section 6. of this document. The following notations are used for
   the YANG model data tree representation.

      <status> <flags> <name> <opts> <type>

        <status> is one of:
          +  for current
          x  for deprecated
          o  for obsolete

        <flags> is one of:
          rw  for read-write configuration data
          ro  for read-only non-configuration data
          -x  for execution rpcs
          -n  for notifications

        <name> is the name of the node

         If the node is augmented into the tree from another module, its
         name is printed as <prefix>:<name>

        <opts> is one of:
          ? for an optional leaf or node


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          ! for a presence container
          * for a leaf-list or list
          Brackets [<keys>] for a list's keys
          Curly braces {<condition>} for optional feature that make node
          conditional

          Colon : for marking case nodes
          Ellipses ("...") subtree contents not shown

          Parentheses enclose choice and case nodes, and case nodes are
          also marked with a colon (":").

        <type> is the name of the type for leafs and leaf-lists.

1.3. 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 |
               +--------+-----------------+-----------+
               | yang   | ietf-yang-types | [RFC6991] |
               | inet   | ietf-inet-types | [RFC6991] |
               +--------+-----------------+-----------+

             Table 1: Prefixes and corresponding YANG modules

2. Characterizing TE Topologies

   The data model proposed by this document takes the following
   characteristics of TE Topologies into account:

   - TE Topology is an abstract control-plane representation of the
     data-plane topology. Hence attributes specific to the data-plane
     must make their way into the corresponding TE Topology modeling.
     The TE Topology comprises of dynamic auto-discovered data (data
     that may change frequently - example: unreserved bandwidth
     available on data-plane links) as well as fairly static data (data
     that rarely changes- examples: layer network identification,
     switching and adaptation capabilities and limitations, fate
     sharing, administrative colors) associated with data-plane nodes
     and links. It is possible for a single TE Topology to encompass TE
     information at multiple switching layers.




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   - TE Topologies are protocol independent. Information about
     topological elements may be learnt via link-state protocols, but
     the topology can exist without being dependent on any particular
     protocol.

   - TE Topology may not be congruent to the routing topology (topology
     constructed based on routing adjacencies) in a given TE System.
     There isn't always a one-to-one association between a TE-link and
     a routing adjacency. For example, the presence of a TE link
     between a pair of nodes doesn't necessarily imply the existence of
     a routing-adjacency between these nodes.

   - Each TE Topological element has an information source associated
     with it. In some scenarios, there could be more than one
     information source associated with each topological element.

   - TE Topologies can be hierarchical. Each node and link of a given
     TE Topology can be associated with respective underlay topology.
     This means that each node and link of a given TE Topology can be
     associated with an independent stack of supporting TE Topologies.

   - TE Topologies can be customized. TE topologies of a given network
     presented by the network provider to its client could be
     customized on per-client request basis. This customization could
     be performed by provider, by client or by provider/client
     negotiation. The relationship between a customized topology (as
     presented to the client) and provider's native topology (as known
     in its entirety to the provider itself) could be captured as
     hierarchical (overlay-underlay), but otherwise the two topologies
     are decoupled from each other.



















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3. Modeling Abstractions and Transformations

      Node-1                                            Node-3
   +------------+                                    +------------+
   |    TTP-1   |                                    |    TTP-1   |
   |LTP  __     |           TE-Tunel-1               |     __     |
   |-6   \/@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\/     |
   o    *  *    oLTP-1           Node-2         LTP-6o    *  *    o
   |   *    *   |           +------------+           |   *    *   |
   |  * TTP-2*  |           |            |           |  * TTP-2*  |
   | *   __   * |LTP-2 LTP-6|            |LTP-1 LTP-5| *   __   * |
   o*    \/    *o-----------o************o-----------o*    \/    *o
   |LTP *  *    | Link-12   |          * | Link-23   |    *  *    |
   |-5 *    *   |      LTP-5|        *   |LTP-2      |   *    *   |
   +--o------o--+           o************o           +--o------o--+
    LTP-4  LTP-3            | *   *    * |            LTP-4  LTP-3
                            |  **     *  |
                            +--o------o--+
                             LTP-4  LTP-3

                Figure 1: TE Topology Modeling Abstractions

3.1. TE Topology

   TE topology is a traffic engineering representation of one or more
   layers of network topologies. TE topology is comprised of TE nodes
   (TE graph vertices) interconnected via TE links (TE graph edges). A
   TE topology is mapped to a TE graph.

3.2. TE Node

   TE node is an element of a TE topology (presented as a vertex on TE
   graph). TE node represents one or several nodes (physical switches),
   or a fraction of a node. TE node belongs to and is fully defined in
   exactly one TE topology. TE node is assigned with the TE topology
   scope unique ID. TE node attributes include information related to
   the data plane aspects of the associated node(s) (e.g. connectivity
   matrix), as well as configuration data (such as TE node name). A
   given TE node can be reached on the TE graph over one of TE links
   terminated by the TE node.

   Multi-layer TE nodes providing switching functions at multiple
   network layers are an example where a physical node can be decomposed
   into multiple logical TE nodes (fractions of a node). Some of these
   (logical) TE nodes may reside in the client layer TE topology while
   the remaining TE nodes belong to the server layer TE topology.



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   In Figure 1, Node-1, Node-2, and Node-3 are TE nodes.

3.3. TE Link

   TE link is an element of a TE topology (presented as an edge on TE
   graph, arrows indicate one or both directions of the TE link). TE
   link represents one or several (physical) links or a fraction of a
   link.  TE link belongs to and is fully defined in exactly one TE
   topology. TE link is assigned with the TE topology scope unique ID.
   TE link attributes include parameters related to the data plane
   aspects of the associated link(s) (e.g. unreserved bandwidth,
   resource maps/pools, etc.), as well as the configuration data (such
   as remote node/link IDs, SRLGs, administrative colors, etc.). TE link
   is connected to TE node, terminating the TE link via exactly one TE
   link termination point (LTP).

   In Figure 1, Link-12 and Link-23 are TE links.

3.4. Transitional TE Link for Multi-Layer Topologies

   Networks are typically composed of multiple network layers where one
   or multiple signals in the client layer network can be multiplexed
   and encapsulated into a server layer signal. The server layer signal
   can be carried in the server layer network across multiple nodes
   until the server layer signal is terminated and the client layer
   signals reappear in the node that terminates the server layer signal.
   Examples of multi-layer networks are: IP over MPLS over Ethernet, low
   order ODUk signals multiplexed into a high order ODUl (l>k) carried
   over an OCh signal (optical transport network).

   TE links as defined in 3.3. can be used to represent links within a
   network layer. In case of a multi-layer network, TE nodes and TE
   links only allow representation of each network layer as a separate
   TE topology Each of these single layer TE topologies would be
   isolated from their client and their server layer TE topology, if
   present (the highest and the lowest network layer in the hierarchy
   only have a single adjacent layer below or above, respectively).
   Multiplexing of client layer signals and encapsulating them into a
   server layer signal requires a function that is provided inside a
   node (typically realized in hardware). This function is also called
   layer transition.

   One of the key requirements for path computation is to be able to
   calculate a path between two endpoints across a multi-layer network
   based on the TE topology representing this multi-layer network. This
   means that an additional TE construct is needed that represents
   potential layer transitions in the multi-layer TE-topology that


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   connects the TE-topologies representing each separate network layer.
   The so-called transitional TE link is such a construct and it
   represents the layer transition function residing inside a node that
   is decomposed into multiple logical nodes that are represented as TE
   nodes. Hence, a transitional TE link connects a client layer node
   with a server layer node. A TE link as defined in 3.3. has LTPs of
   exactly the same kind on each link end whereas the transitional TE
   link has client layer LTPs on the client side of the transitional
   link and in most cases a single server layer LTP on the server side.
   It should be noted that transitional links are a helper construct in
   the multi-layer TE topology and they only exist as long as they are
   not in use (as they represent potential connectivity). When the
   server layer trail has been established between the server layer LTP
   of two transitional links in the server layer network, the resulting
   client layer link in the data plane will be represented as a normal
   TE link in the client layer topology. The transitional TE links will
   re-appear when the server layer trail has been torn down.

      +------------------+
      | +------+         |                          +------+
   -----|Client|------+  |              Client -----|Client|
      | |Layer |---+  |  |              Layer       |Layer |
   -----|Switch|-+ |  |  |              Links  -----|Node  |
      | +------+ | |  |  |                          +------+
      |          | |  |  | Client                    | |  |
      |          | | ---_| Layer                     --- ---
   ***|**********|*| \ /*|***************************\ /*\ /****
      |          ---  |  | Server       Transitional  |   |
      |    Layer \ /  |  | Layer               Links  |   |
      |    Term.  |   |  |                            |   |
      |           |   |  |                            |   |
      |         +------+ |                          +------+
   =============|Server|=====            Server ====|Server|====
      |         |Layer | |               Layer      |Layer |
   =============|Switch|=====            Links  ====|Node  |====
      |         +------+ |                          +------+
      +------------------+

       Physical Node View                       TE-Topology View

       Figure 2: Modeling a Multi-Layer Node (Dual-Layer Example)

3.5. TE Link Termination Point (LTP)

   TE link termination point (LTP) is a conceptual point of connection
   of a TE node to one of the TE links, terminated by the TE node.
   Cardinality between an LTP and the associated TE link is 1:0..1.


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   In Figure 1, Node-2 has six LTPs: LTP-1 to LTP-6.

3.6. TE Tunnel Termination Point (TTP)

   TE tunnel termination point (TTP) is an element of TE topology
   representing one or several of potential transport service
   termination points (i.e. service client adaptation points such as
   WDM/OCh transponder). TTP is associated with (hosted by) exactly one
   TE node. TTP is assigned with the TE node scope unique ID. Depending
   on the TE node's internal constraints, a given TTP hosted by the TE
   node could be accessed via one, several or all TE links terminated by
   the TE node.

   In Figure 1, Node-1 has two TTPs: TTP-1 and TTP-2.

3.7. TE Node Connectivity Matrix

   TE node connectivity matrix is a TE node's attribute describing the
   TE node's switching limitations in a form of valid switching
   combinations of the TE node's LTPs (see below). From the point of
   view of a potential TE path arriving at the TE node at a given
   inbound LTP, the node's connectivity matrix describes valid
   (permissible) outbound LTPs for the TE path to leave the TE node
   from.

   In Figure 1, the connectivity matrix on Node-2 is:
   {<LTP-6, LTP-1>, <LTP-5, LTP-2>, <LTP-5, LTP-4>, <LTP-4, LTP-1>,
   <LTP-3, LTP-2>}

3.8. TTP Local Link Connectivity List (LLCL)

   TTP Local Link Connectivity List (LLCL) is a List of TE links
   terminated by the TTP hosting TE node (i.e. list of the TE link
   LTPs), which the TTP could be connected to. From the point of view of
   a potential TE path LLCL provides a list of valid TE links the TE
   path needs to start/stop on for the connection, taking the TE path,
   to be successfully terminated on the TTP in question.

   In Figure 1, the LLCL on Node-1 is:
   {<TTP-1, LTP-5>, <TTP-1, LTP-2>, <TTP-2, LTP-3>, <TTP-2, LTP4>}

3.9. TE Path

   TE path is an ordered list of TE links and/or TE nodes on the TE
   topology graph, inter-connecting a pair of TTPs to be taken by a
   potential connection. TE paths, for example, could be a product of
   successful path computation performed for a given transport service.


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   In Figure 1, the TE Path for TE-Tunnel-1 is:
   {Node-1:TTP-1, Link-12, Node-2, Link-23, Node-3:TTP1}

3.10. TE Inter-Layer Lock

   TE inter-layer lock is a modeling concept describing client-server
   layer adaptation relationships and hence important for the multi-
   layer traffic engineering. It is an association of M client layer
   LTPs and N server layer TTPs, within which data arriving at any of
   the client layer LTPs could be adopted onto any of the server layer
   TTPs. TE inter-layer lock is identified by inter-layer lock ID, which
   is unique across all TE topologies provided by the same provider. The
   client layer LIPs and the server layer TTPs associated within a given
   TE inter-layer lock are decorated with the same inter-layer lock ID
   attribute.

             (IL-1) C-LTP-1 +------------+   C-LTP-2 (IL-1)
                    --------O   (IL-1)   O--------
             (IL-1) C-LTP-3 |   S-TTP-1  |   C-LTP-4 (IL-1)
                    --------O     __     0--------
             (IL-1) C-LTP-5 |    *\/*    |   C-LTP-5 (IL-1)
                    --------O   *    *   O--------
                            |  *(IL-1)*  |
                    S-LTP-3 | * S-TTP-2* |   S-LTP-4
                    --------o*    __    *o--------
                            |    *\/*    |
                            |   *    *   |
                            +--o------o--+
                       S-LTP-1 |      | S-LTP-2

             Figure 3: TE Inter-Layer Lock ID Associations

   On the picture above a TE inter-layer lock with IL_1 ID associates 6
   client layer LTPs (C-LTP-1 - C-LTP-6) with two server layer TTPs (S-
   TTP-1 and S-TTP-2). They all have the same attribute - TE inter-layer
   lock ID:  IL-1, which is the only thing that indicates the
   association. A given LTP may have 0, 1 or more inter-layer lock IDs.
   In the latter case this means that the data arriving at the LTP may
   be adopted onto any of TTPs associated with all specified inter-layer
   locks. For example, C-LTP-1 could have two inter-layer lock IDs - IL-
   1 and IL-2. This would mean that C-LTP-1 for adaptation purposes
   could use not just TTPs associated with inter-layer lock IL-1 (i.e.
   S-TTP-1 and S-TTP-2 on the picture), but any of TTPs associated with
   inter-layer lock IL-2 as well. Likewise, a given TTP may have one or
   more inter-layer lock IDs, meaning that it can offer the adaptation
   service to any of client layer LTPs with inter-layer lock ID matching
   one of its own. Additionally, each TTP has an attribute - Unreserved


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   Adaptation Bandwidth, which announces its remaining adaptation
   resources sharable between all potential client LTPs.

   LTPs and TTPs associated within the same TE inter-layer lock may be
   hosted by the same (hybrid, multi-layer) TE node or multiple TE nodes
   located in the same or separate TE topologies. The latter is
   especially important since TE topologies of different layer networks
   could be modeled by separate augmentations of the basic (common to
   all layers) TE topology model.

3.11. Underlay TE topology

   Underlay TE topology is a TE topology that serves as a base for
   constructing of overlay TE topologies

3.12. Overlay TE topology

   Overlay TE topology is a TE topology constructed based on one or more
   underlay TE topologies. Each TE node of the overlay TE topology
   represents an arbitrary segment of an underlay TE topology; each TE
   link of the overlay TE topology represents an arbitrary TE path in
   one of the underlay TE topologies. The overlay TE topology and the
   supporting underlay TE topologies may represent distinct layer
   networks (e.g. OTN/ODUk and WDM/OCh respectively) or the same layer
   network.

3.13. Abstract TE topology

   Abstract TE topology is a topology that contains abstract topological
   elements (nodes, links, tunnel termination points). Abstract TE
   topology is an overlay TE topology created by a topology provider and
   customized for a topology provider's client based on one or more of
   the provider's native TE topologies (underlay TE topologies), the
   provider's policies and the client's preferences. For example, a
   first level topology provider (such as Domain Controller) can create
   an abstract TE topology for its client (e.g. Multi-Domain Service
   Coordinator) based on the provider's one or more native TE
   topologies, local policies/profiles and the client's TE topology
   configuration requests

   Figure 4 shows an example of abstract TE topology.








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     +---+              +---+
     |s31|--------------|S5 |
     +---+\           / +---+
           \         /
            \       /
             \+---+/                +---+
             /|AN1|\----------------|S8 |
            / +---+ \               +---+
     +---+ /         \ +---+
     |S9 |-------------|S11|
     +---+             +---+
           Abstract TE Topology


            +---+                    +---+
            |S1 |--------------------|S2 |
            +---+                    +---+
             /                          \
            /                            \
     +---+ /                  +---+       \ +---+
     |s3 |--------------------|S4 |---------|S5 |
     +---+\                   +---+         +---+
           \                      \             \
            \                      \             \
             \+---+                 +---+         +---+
             /|S6 |\                |S7 |---------|S8 |
            / +---+ \               +---+\       /+---+
     +---+ /         \ +---+              +---+ /
     |S9 |-------------|S10|--------------|S11|/
     +---+             +---+              +---+
           Native TE Topology

         Figure 4: Abstract TE Topology

4. Model Applicability

4.1. Native TE Topologies

   The model discussed in this draft can be used to represent and
   retrieve native TE topologies on a given TE system.









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     +---+       +---+        +---+         +---+         +---+
     | R1|-------| R2|--------| R3|---------| R4|---------| R5|
     +---+       +---+        +---+         +---+         +---+
       |                      /   \         /   \         /
       |                     /     \       /     \       /
       |                    /       \     /       \     /
       |                   /         \   /         \   /
       |                  /           \ /           \ /
     +---+             +---+         +---+         +---+
     | R6|-------------| R7|         | R8|---------| R9|
     +---+             +---+         +---+         +---+

               Figure 5a: Example Network Topology

   Consider the network topology depicted in Figure 5a (R1 .. R9 are
   nodes representing routers). An implementation MAY choose to
   construct a native TE Topology using all nodes and links present in
   the given TED as depicted in Figure 5b. The data model proposed in
   this document can be used to retrieve/represent this TE topology.

          ---------------
          | Native      |                   |  [ ] TE Node
          | TE-Topology |                   |  +++ TE Link
          ---------------                   o--------------

      [R1] ++++ [R2] ++++ [R3] ++++ [R4] ++++ [R5]
        +                +    +    +    +    +
        +               +      +  +      +  +
        +              +        ++        ++
      [R6] +++++++++ [R7]      [R8] ++++ [R9]

               Figure 5b: Native TE Topology as seen on Node R3

   Consider the case of the topology being split in a way that some
   nodes participate in OSPF-TE while others participate in ISIS-TE
   (Figure 6a). An implementation MAY choose to construct separate TE
   Topologies based on the information source. The native TE Topologies
   constructed using only nodes and links that were learnt via a
   specific information source are depicted in Figure 6b. The data model
   proposed in this document can be used to retrieve/represent these TE
   topologies.

   Similarly, the data model can be used to represent/retrieve a TE
   Topology that is constructed using only nodes and links that belong
   to a particular technology layer. The data model is flexible enough
   to retrieve and represent many such native TE Topologies.



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                                     :
   TE info distributed via ISIS-TE   :  TE info distributed via OSPF-TE
                                     :
          +---+       +---+        +---+         +---+         +---+
          | R1|-------| R2|--------| R3|---------| R4|---------| R5|
          +---+       +---+        +---+         +---+         +---+
            |                      / : \         /   \         /
            |                     /  :  \       /     \       /
            |                    /   :   \     /       \     /
            |                   /    :    \   /         \   /
            |                  /     :     \ /           \ /
          +---+             +---+    :    +---+         +---+
          | R6|-------------| R7|    :    | R8|---------| R9|
          +---+             +---+    :    +---+         +---+
                                     :


                    Figure 6a: Example Network Topology


           -----------------------   :  -----------------------
           |Native TE Topology   |   :  |Native TE Topology   |
           |Info-Source: ISIS-TE |   :  |Info-Source: OSPF-TE |
           -----------------------   :  -----------------------
                                     :
            [R1] ++++ [R2] ++++ [R3] : [R3'] ++++ [R4] ++++ [R5]
             +                +      :      +    +    +    +
             +               +       :       +  +      +  +
             +              +        :        ++        ++
            [R6] +++++++++ [R7]      :       [R8] ++++ [R9]


               Figure 6b: Native TE Topologies as seen on Node R3


4.2. Customized TE Topologies

   Customized TE topology is a topology that was modified by the
   provider to honor a particular client's requirements or preferences.
   The model discussed in this draft can be used to represent, retrieve
   and manipulate customized TE Topologies. The model allows the
   provider to present the network in abstract TE Terms on a per client
   basis. These customized topologies contain sufficient information for
   the path computing client to select paths according to its policies.





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                                  | +---+            /-\
                                  | |   | Router    (   ) WDM
                                  | +---+ Node       \-/  node
                                  |
                                  o----------------------------

     +---+        /-\          /-\           /-\          +---+
     | R1|-------( A )--------( C )---------( E )---------| R3|
     +---+        \-/          \-/           \-/          +---+
                              /   \         /   \
                             /     \       /     \
                            /       \     /       \
                           /         \   /         \
                          /           \ /           \
         +---+          /-\           /-\           /-\          +---+
         | R2|---------( B )---------( D )---------( F )---------| R4|
         +---+          \-/           \-/           \-/          +---+

               Figure 7: Example packet optical topology

   Consider the network topology depicted in Figure 7. This is a typical
   packet optical transport deployment scenario where the WDM layer
   network domain serves as a Server Network Domain providing transport
   connectivity to the packet layer network Domain (Client Network
   Domain). Nodes R1, R2, R3 and R4 are IP routers that are connected to
   an Optical WDM transport network. A, B, C, D, E and F are WDM nodes
   that constitute the Server Network Domain.

                                            | *****  B-F WDM Path
                                            | @@@@@  B-E WDM Path
                                            | $$$$$  A-E WDM Path
                                            o--------------------

     +---+        /-\ $$$$$$$$ /-\ $$$$$$$$$ /-\          +---+
     | R1|-------( A )--------( C )---------( E )---------| R3|
     +---+        \-/         @\-/ @@@@@@@@@ \-/          +---+
                             @/   \         /   \
                            @/     \       /     \
                           @/       \     /       \
                          @/         \   /         \
                         @/           \ /           \
         +---+          /-\ ********* /-\ ********* /-\          +---+
         | R2|---------( B )---------( D )---------( F )---------| R4|
         +---+          \-/           \-/           \-/          +---+

                Figure 8a: Paths within the provider domain



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                 ++++++++ [A] ++++++++++++++++++++ [E] +++++++++
                                              +++++
                                          ++++
                                      ++++
                                  ++++
                              ++++
                 ++++++++ [B] ++++++++++++++++++++ [F] +++++++++

         Figure 8b: Customized TE Topology provided to the Client

   The goal here is to augment the Client TE Topology with a customized
   TE Topology provided by the WDM network. Given the availability of
   the paths A-E, B-F and B-E (Figure 8a), a customized TE Topology as
   depicted in Figure 8b is provided to the Client. This customized TE
   Topology is merged with the Client's Native TE Topology and the
   resulting topology is depicted in Figure 8c.


            [R1] ++++++++ [A] ++++++++++++++++++++ [E] +++++++++ [R3]
                                              +++++
                                          ++++
                                      ++++
                                  ++++
                              ++++
            [R2] ++++++++ [B] ++++++++++++++++++++ [F] +++++++++ [R4]

   Figure 8c: Customized TE Topology merged with the Client's Native TE
                                 Topology


   The data model proposed in this document can be used to
   retrieve/represent/manipulate the customized TE Topology depicted in
   Figure 8b.

   A customized TE topology is not necessarily an abstract TE topology.
   he provider may produce, for example, an abstract TE topology of
   certain type (e.g. single-abstract-node-with-connectivit-matrix
   topology, a border_nodes_connected_via_mesh_of_abstract_links
   topology, etc.) and expose it to all/some clients in expectation that
   the clients will use it without customization.
   On the other hand, a client may request a customized version of the
   provider's native TE topology (e.g. by requesting removal of TE links
   which belong to certain layers, are too slow, not protected and/or
   have a certain affinity). Note that the resulting TE topology will



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   not be abstract (because it will not contain abstract elements), but
   customized (modified upon client's instructions).

   The client ID field in the TE topology identifier (Section 5.4.
   indicates which client the TE topology is customized for. Although a
   authorized client MAY receive a TE topology with the client ID field
   matching some other client, the client can customize only TE
   topologies with the client ID field either 0 or matching the ID of
   the client in question. If the client starts reconfiguration of a
   topology its client ID will be automatically set in the topology ID
   field for all future configurations and updates wrt. the topology in
   question.

   The provider MAY tell the client that a given TE topology cannot be
   re-negotiated, by setting its own (provider's) ID in the client ID
   field of the topology ID.

4.3. Merging TE Topologies Provided by Multiple Providers

   A client may receive TE topologies provided by multiple providers,
   each of which managing a separate domain of multi-domain network. In
   order to make use of said topologies, the client is expected to merge
   the provided TE topologies into one or more client's native TE
   topologies, each of which homogeneously representing the multi-domain
   network. This makes it possible for the client to select end-to-end
   TE paths for its services traversing multiple domains.

   In particular, the process of merging TE topologies includes:

   - Identifying neighboring domains and locking their topologies
     horizontally by connecting their inter-domain open-ended TE links;
   - Renaming TE node, link, and SRLG IDs to ones allocated from a
     separate name space; this is necessary because all TE topologies
     are considered to be, generally speaking, independent with a
     possibility of clashes among TE node, link or SRLG IDs;
   - Locking, vertically, TE topologies associated with different layer
     networks, according to provided topology inter-layer locks; this is
     to facilitate inter-layer path computations across multiple TE
     topologies provided by the same topology provider.









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     /---\      +---+    +---+      +---+    +---+      /---\
     |s3 |------|S13|----|S15|------|S23|----|S25|------|C21|
     \---/      +---+\   +---+      +---+   /+---+      \---/
                      \                    /
                       \                  /
                        \+---+      +---+/   +---+      /---\
                         |S18|------|S24|    |S28|------|C22|
                         +---+      +---+\  /+---+      \---/
                                          \/
                                          /\
     /---\      +---+    +---+      +---+/  \+---+      /---\
     |C12|------|S19|----|S17|------|S29|----|S27|------|C23|
     \---/      +---+    +---+      +---+    +---+      \---/


        Domain 1 TE Topology              Domain 2 TE Topology

             +---+    +---+                  +---+    +---+
        -----|S13|----|S15|----          ----|S23|----|S25|----
             +---+\   +---+                  +---+   /+---+
                   \                                /
                    \                              /
                     \+---+                  +---+/   +---+
                      |S18|----          ----|S24|    |S28|----
                      +---+                  +---+\  /+---+
                                                   \/
                                                   /\
             +---+    +---+                  +---+/  \+---+
        -----|S19|----|S17|----          ----|S29|----|S27|----
             +---+    +---+                  +---+    +---+

         Figure 9: Merging Domain TE Topologies

   Figure 9 illustrates the process of merging, by the client, of TE
   topologies provided by the client's providers. In the Figure, each of
   the two providers caters to the client (abstract or native) TE
   topology, describing the network domain under the respective
   provider's control. The client, by consulting the attributes of the
   inter-domain TE links - such as inter-domain plug IDs or remote TE
   node/link IDs (as defined by the TE Topology model) - is able to
   determine that:

   a) the two domains are adjacent and are inter-connected via three
     inter-domain TE links, and;




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   b) each domain is connected to a separate customer site, connecting
     the left domain in the Figure to customer devices C-11 and C-12,
     and the right domain to customer devices C-21, C-22 and C-23.

   Therefore, the client inter-connects the open-ended TE links, as
   shown on the upper part of the Figure.

   As mentioned, one way to inter-connect the open-ended inter-domain TE
   links of neighboring domains is to mandate the providers to specify
   remote nodeID/linkID attribute in the provided inter-domain TE links.
   This, however, may prove to be not flexible. For example, the
   providers may not know the respective remote nodeIDs/ linkIDs. More
   importantly, this option does not allow for the client to mix-n-match
   multiple (more than one) topologies catered by the same providers
   (see below). Another, more flexible, option to resolve the open-ended
   inter-domain TE links is by decorating them with the inter-domain
   plug ID attribute. Inter-domain plug ID is a network-wide unique
   number that identifies on the network a connectivity supporting a
   given inter-domain TE link. Instead of specifying remote node ID/link
   ID, an inter-domain TE link may provide a non-zero inert-domain plug
   ID. It is expected that two neighboring domain TE topologies
   (provided by separate providers) will have each at least one open-
   ended inter-domain TE link with an inter-domain plug ID matching to
   one provided by its neighbor. For example, the inter-domain TE link
   originating from node S5 of the Domain 1 TE topology (Figure 1) and
   the inter-domain TE link coming from node S3 of Domain2 TE topology
   may specify matching inter-domain plug ID (e.g. 175344)  This allows
   for the client to identify adjacent nodes in the separate neighboring
   TE topologies and resolve the inter-domain TE links connecting them
   regardless of their respective nodeIDs/linkIDs (which, as mentioned,
   could be allocated from independent name spaces). Inter-domain plug
   IDs may be assigned and managed by a central network authority.
   Alternatively, inter-domain plug IDs could be dynamically auto-
   discovered (e.g. via LMP protocol).

   Furthermore, the client renames the TE nodes, links and SRLGs offered
   in the abstract TE topologies by assigning to them IDs allocated from
   a separate name space managed by the client. Such renaming is
   necessary, because the two abstract TE topologies may have their own
   name spaces, generally speaking, independent one from another; hence,
   ID overlaps/clashes are possible. For example, both TE topologies
   have TE nodes named S7, which, after renaming, appear in the merged
   TE topology as S17 and S27, respectively.

   Once the merging process is complete, the client can use the merged
   TE topology for path computations across both domains, for example,
   to compute a TE path connecting C-11 to C-23.


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4.4. Dealing with Multiple Abstract TE Topologies Provided by the Same
   Provider

      Domain 1 Abstract TE Topology 1   Domain 2 Abstract TE Topology 1

             +---+    +---+                  +---+    +---+
        -----|S13|----|S15|----          ----|S23|----|S25|----
             +---+\   +---+                  +---+   /+---+
                   \                                /
                    \                              /
                     \+---+                  +---+/   +---+
                      |S18|----          ----|S24|    |S28|----
                      +---+                  +---+\  /+---+
                                                   \/
                                                   /\
             +---+    +---+                  +---+/  \+---+
        -----|S19|----|S17|----          ----|S29|----|S27|----
             +---+    +---+                  +---+    +---+


      Domain 1 Abstract TE Topology 1   Domain 2 Abstract TE Topology 1

             +------------+                  +------------+
        -----|            |----          ----|            |----
             |            |                  |            |
             |    AN1     |----          ----|    AN1     |----
             |            |                  |            |
        -----|            |----          ----|            |----
             +------------+                  +------------+

         Figure 10: Merging Domain TE Topologies

   Based on local configuration, templates and/or policies pushed by the
   client, a given provider may expose more than one abstract TE
   topology to the client. For example, one abstract TE topology could
   be optimized based on a lowest-cost criterion, while another one
   could be based on best possible delay metrics, while yet another one
   could be based on maximum bandwidth availability for the client
   services. Furthermore, the client may request all or some providers
   to expose additional abstract TE topologies, possibly of a different
   type and/or optimized differently, as compared to already-provided TE
   topologies. In any case, the client should be prepared for a provider
   to offer to the client more than one abstract TE topology.


   It should be up to the client (based on the client's local
   configuration and/or policies conveyed to the client by the client's


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   clients) to decide how to mix-and-match multiple abstract TE
   topologies provided by each or some of the providers, as well as how
   to merge them into the client's native TE topologies. The client also
   decides how many such merged TE topologies it needs to produce and
   maintain. For example, in addition to the merged TE topology depicted
   in the upper part of Figure 1, the client may merge the abstract TE
   topologies received from the two providers, as shown in Figure 10,
   into the client's additional native TE topologies, as shown in Figure
   11.

   Note that allowing for the client mix-n-matching of multiple TE
   topologies assumes that inter-domain plug IDs (rather than remote
   nodeID/linkID) option is used for identifying neighboring domains and
   inter-domain TE link resolution.



































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                Client's Merged TE Topology 2

     /---\      +------------+      +------------+      /---\
     |s3 |------|            |------|            |------|C21|
     \---/      |            |      |            |      \---/
                |            |      |            |
                |            |      |            |
                |            |      |            |      /---\
                |    AN11    |------|    AN21    |------|C22|
                |            |      |            |      \---/
                |            |      |            |
                |            |      |            |
     /---\      |            |      |            |      /---\
     |C12|------|            |------|            |------|C23|
     \---/      +------------+      +------------+      \---/


                Client's Merged TE Topology 3

     /---\      +------------+      +---+    +---+      /---\
     |s3 |------|            |------|S23|----|S25|------|C21|
     \---/      |            |      +---+   /+---+      \---/
                |            |             /
                |            |            /
                |            |      +---+/   +---+      /---\
                |    AN11    |------|S24|    |S28|------|C22|
                |            |      +---+\  /+---+      \---/
                |            |            \/
                |            |            /\
     /---\      |            |      +---+/  \+---+      /---\
     |C12|------|            |------|S29|----|S27|------|C23|
     \---/      +------------+      +---+    +---+      \---/

     Figure 11: Multiple Native (Merged) Client's TE Topologies

   It is important to note that each of the three native (merged) TE
   topologies could be used by the client for computing TE paths for any
   of the multi-domain services. The choice as to which topology to use
   for a given service depends on the service parameters/requirements
   and the topology's style, optimization criteria and the level of
   details.








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5. Modeling Considerations

5.1. Network topology building blocks

   The network topology building blocks are discussed in [YANG-NET-
   TOPO]. The TE Topology model proposed in this document augments and
   uses the ietf-network-topology module defined in [YANG-NET-TOPO].

                  +------------------------+
                  |                        |
                  | Network Topology Model |
                  | (ietf-network-topology)|
                  +------------------------+
                               |
                               |
                               |
                               V
                  +------------------------+
                  |       TE Topology      |
                  |         Model          |
                  |                        |
                  +------------------------+

             Figure 12: Augmenting the Network Topology Model


5.2. Technology agnostic TE Topology model

   The TE Topology model proposed in this document is meant to be
   network technology agnostic. Other technology specific TE Topology
   models can augment and use the building blocks provided by the
   proposed model.

















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                  +-----------------------------+
                  |      TE Topology Model      |
                  | (Defined in This Document)  |
                  +-----------------------------+
                                 |
            +-------------+-------------+-------------+
            |             |             |             |
            V             V             V             V
      +------------+                            +------------+
      | Technology |                            | Technology |
      |  Specific  |   ......................   |  Specific  |
      | TE Topology|                            | TE Topology|
      |   Model 1  |                            |   Model n  |
      +------------+                            +------------+

   Figure 13: Augmenting the Technology agnostic TE Topology model

5.3. Model Structure

   The high-level model structure proposed by this document is as shown
   below:

   module: ietf-te-topology
   augment /nw:networks/nw:network/nw:network-types:
      +--rw te-topology!

   augment /nw:networks:
      +--rw te!
         +--rw templates
            +--rw node-template* [name] {template}?
            |  ............
            +--rw link-template* [name] {template}?
               ............

   augment /nw:networks/nw:network:
      +--rw provider-id?      te-types:te-global-id
      +--rw client-id?        te-types:te-global-id
      +--rw te-topology-id?   te-types:te-topology-id
      +--rw te!
         |  ............

   augment /nw:networks/nw:network/nw:node:
      +--rw te-node-id?   te-types:te-node-id
      +--rw te!
         |  ............
         +--rw tunnel-termination-point* [tunnel-tp-id]
            +--rw tunnel-tp-id    binary


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            |  ............
            +--rw supporting-tunnel-termination-point* [node-ref tunnel-
   tp-ref]
               |  ............


   augment /nw:networks/nw:network/nt:link:
      +--rw te!
         |  ..........

   augment /nw:networks/nw:network/nw:node/nt:termination-point:
      +--rw te-tp-id?   te-types:te-tp-id
      +--rw te!
         |  ............

5.4. Topology Identifiers

   The TE-Topology is uniquely identified by a key that has 3
   constituents - te-topology-id, provider-id and client-id. The
   combination of provider-id and te-topology-id uniquely identifies a
   native TE Topology on a given provider. The client-id is used only
   when Customized TE Topologies come into play; a value of "0" is used
   as the client-id for native TE Topologies.

   augment /nw:networks/nw:network:
      +--rw te!
         +--rw provider-id       te-global-id
         +--rw client-id         te-global-id
         +--rw te-topology-id    te-topology-id

5.5. Generic TE Link Attributes

   The model covers the definitions for generic TE Link attributes -
   bandwidth, admin groups, SRLGs, switching capabilities, TE metric
   extensions etc.

     +--rw te-link-attributes
        .....................
        +--rw admin-status?                     te-admin-status
        |  .....................
        +--rw link-index?                       uint64
        +--rw administrative-group?             te-types:admin-groups
        +--rw link-protection-type?             enumeration
        +--rw max-link-bandwidth?               te-bandwidth
        +--rw max-resv-link-bandwidth?          te-bandwidth
        +--rw unreserved-bandwidth* [priority]
        |  .....................


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        +--rw te-default-metric?                uint32
        |  .....................
        +--rw te-srlgs
        +--rw te-nsrlgs {nsrlg}?        .....................


5.6. Generic TE Node Attributes

   The model covers the definitions for generic TE Node attributes.

   The definition of a generic connectivity matrix is shown below:

     +--rw te-node-attributes
        ...........
        +--rw connectivity-matrices
        ...........
        |  +--rw connectivity-matrix* [id]
        |  |  +--rw id            uint32
        |  |  +--rw from
        |  |  |  +--rw tp-ref?        leafref
        |  |  |  +--rw label-restriction* [inclusive-exclusive label-
   start]
        |  |  +--rw to
        |  |  |  +--rw tp-ref?        leafref
        |  |  |  +--rw label-restriction* [inclusive-exclusive label-
   start]
        |  |  +--rw is-allowed?   boolean
        ...........
        |  |  +--rw underlay! {te-topology-hierarchy}?
        ...........
        |  |  +--rw path-constraints
        ...........
        |  |  +--rw optimizations
        ...........
        |  |  +--ro computed-path-properties
        ...........

   The definition of a TTP Local Link Connectivity List is shown below:

     +--rw tunnel-termination-point* [tunnel-tp-id]
        +--rw tunnel-tp-id               binary
        +--rw admin-status?              te-types:te-admin-status
        +--rw name?                      string
        +--rw switching-capability?      identityref
        +--rw encoding?                  identityref
        +--rw inter-layer-lock-id?       uint32
        +--rw protection-type?           Identityref


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        +--rw client-layer-adaptation
        ...........
        +--rw local-link-connectivities
        ...........
        |  +--rw local-link-connectivity* [link-tp-ref]
        |     +--rw link-tp-ref                leafref
        |     +--rw label-restriction* [inclusive-exclusive label-start]
        ...........
        |     +--rw is-allowed?                 boolean
        |     +--rw underlay {te-topology-hierarchy}?
        ...........
        |     +--rw path-constraints
        ...........
        |     +--rw optimizations
        ...........
        |     +--ro computed-path-properties
        ...........
        +--rw supporting-tunnel-termination-point* [node-ref tunnel-tp-
   ref]
           +--rw node-ref         inet:uri
           +--rw tunnel-tp-ref    binary

   The attributes directly under container connectivity-matrices are the
   default attributes for all connectivity-matrix entries when the per
   entry corresponding attribute is not specified. When a per entry
   attribute is specified, it overrides the cooresponding attribute
   directly under the container connectivity-matrices. The same rule
   applies to the attributes directly under container local-link-
   connectivities.

   Each TTP (Tunnel Termination Point) MAY be supported by one or more
   supporting TTPs. If the TE node hosting the TTP in question refers to
   a supporting TE node, then the supporting TTPs are hosted by the
   supporting TE node. If the TE node refers to an underlay TE topology,
   the supporting TTPs are hosted by one or more specified TE nodes of
   the underlay TE topology.

5.7. TED Information Sources

   The model allows each TE topological element to have multiple TE
   information sources (OSPF-TE, ISIS-TE, BGP-LS, User-Configured,
   System-Processed, Other). Each information source is associated with
   a credibility preference to indicate precedence. In scenarios where a
   customized TE Topology is merged into a Client's native TE Topology,
   the merged topological elements would point to the corresponding
   customized TE Topology as its information source.



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   augment /nw:networks/nw:network/nw:node:
      +--rw te!
         ...........
         +--ro information-source?         te-info-source
         +--ro information-source-state
         |  +--ro credibility-preference?    uint16
         |  +--ro logical-network-element?   string
         |  +--ro network-instance?          string
         |  +--ro topology
         |     +--ro node-ref?      leafref
         |     +--ro network-ref?   leafref
         +--ro information-source-entry* [information-source]
         |  +--ro information-source          te-info-source
               ............

   augment /nw:networks/nw:network/nt:link:
      +--rw te!
         ...........
         +--ro information-source?         te-info-source
         +--ro information-source-state
         |  +--ro credibility-preference?    uint16
         |  +--ro logical-network-element?   string
         |  +--ro network-instance?          string
         |  +--ro topology
         |     +--ro link-ref?      leafref
         |     +--ro network-ref?   leafref
         +--ro information-source-entry* [information-source]
         |  +--ro information-source                te-info-source
               ............

5.8. Overlay/Underlay Relationship

   The model captures overlay and underlay relationship for TE
   nodes/links. For example - in networks where multiple TE Topologies
   are built hierarchically, this model allows the user to start from a
   specific topological element in the top most topology and traverse
   all the way down to the supporting topological elements in the bottom
   most topology.

   This relationship is captured via the "underlay-topology" field for
   the node and via the "underlay" field for the link. The use of these
   fields is optional and this functionality is tagged as a "feature"
   ("te-topology-hierarchy").

   augment /nw:networks/nw:network/nw:node:
      +--rw te-node-id?   te-types:te-node-id
      +--rw te!


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         +--rw te-node-template*           leafref {template}?
         +--rw te-node-attributes
         |  +--rw admin-status?            te-types:te-admin-status
         |  |  ....................
         |  +--rw underlay-topology {te-topology-hierarchy}?
         |     +--rw network-ref?   leafref

   augment /nw:networks/nw:network/nt:link:
      +--rw te!
         +--rw te-link-attributes
         |  ....................
         |  +--rw underlay {te-topology-hierarchy}?
         |  |  +--rw enabled?                     boolean
         |  |  +--rw primary-path
         |  |  |  +--rw network-ref?    leafref
         |  |  |     ....................
         |  |  +--rw backup-path* [index]
         |  |  |  +--rw index           uint32
         |  |  |  +--rw network-ref?    leafref
         |  |  |     ....................
         |  |  +--rw protection-type?             identityref
         |  |  +--rw tunnel-termination-points
         |  |  |  +--rw source?        binary
         |  |  |  +--rw destination?   binary
         |  |  +--rw tunnels
         |  |  |  ....................

5.9. Templates

   The data model provides the users with the ability to define
   templates and apply them to link and node configurations. The use of
   "template" configuration is optional and this functionality is tagged
   as a "feature" ("template").

     +--rw topology* [provider-id client-id te-topology-id]
     |  ...........
     |  +--rw node* [te-node-id]
     |  |  +--rw te-node-template?     leafref {template}?
     |  |     ..........
     |  +--rw link* [source-te-node-id source-te-link-id dest-te-node-id
   dest-te-link-id]
     |     +--rw te-link-template?     leafref {template}?
     |        ..........

   augment /nw:networks:
      +--rw te!
         +--rw templates


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            +--rw node-template* [name] {template}?
            |  +--rw name                       te-types:te-template-
   name
            |  +--rw priority?                  uint16
            |  +--rw reference-change-policy?   enumeration
            |  +--rw te-node-attributes
               ..........
            +--rw link-template* [name] {template}?
               +--rw name                       te-types:te-template-
   name
               +--rw priority?                  uint16
               +--rw reference-change-policy?   enumeration
               +--rw te-link-attributes
               ..........

   Multiple templates can be specified to a configuration element. When
   two or more templates specify values for the same configuration
   field, the value from the template with the highest priority is used.
   The reference-change-policy specifies the action that needs to be
   taken when the template changes on a configuration element that has a
   reference to this template. The choices of action include taking no
   action, rejecting the change to the template and applying the change
   to the corresponding configuration. [Editor's Note: The notion of
   "templates" has wider applicability. It is possible for this to be
   discussed in a separate document.]

5.10. Scheduling Parameters

   The model allows time scheduling parameters to be specified for each
   topological element or for the topology as a whole. These parameters
   allow the provider to present different topological views to the
   client at different time slots. The use of "scheduling parameters" is
   optional.

   The YANG data model for configuration scheduling is defined in [YANG-
   SCHEDULE], which allows specifying configuration schedules without
   altering this data model.

5.11. Notifications

   Notifications are a key component of any topology data model.

   [YANG-PUSH] and [RFC5277bis] define a subscription and push mechanism
   for YANG datastores. This mechanism currently allows the user to:

   - Subscribe notifications on a per client basis



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   - Specify subtree filters or xpath filters so that only interested
     contents will be sent.
   - Specify either periodic or on-demand notifications.

6. Tree Structure

   module: ietf-te-topology
   augment /nw:networks/nw:network/nw:network-types:
      +--rw te-topology!
   augment /nw:networks:
      +--rw te!
         +--rw templates
            +--rw node-template* [name] {template}?
            |  +--rw name                       te-types:te-template-
   name
            |  +--rw priority?                  uint16
            |  +--rw reference-change-policy?   enumeration
            |  +--rw te-node-attributes
            |     +--rw admin-status?        te-types:te-admin-status
            |     +--rw domain-id?           uint32
            |     +--rw is-abstract?         empty
            |     +--rw name?                inet:domain-name
            |     +--rw signaling-address*   inet:ip-address
            |     +--rw underlay-topology {te-topology-hierarchy}?
            |        +--rw network-ref?   leafref
            +--rw link-template* [name] {template}?
               +--rw name                       te-types:te-template-
   name
               +--rw priority?                  uint16
               +--rw reference-change-policy?   enumeration
               +--rw te-link-attributes
                  +--rw access-type?                      te-types:te-
   link-access-type
                  +--rw external-domain
                  |  +--rw network-ref?            leafref
                  |  +--rw remote-te-node-id?      te-types:te-node-id
                  |  +--rw remote-te-link-tp-id?   te-types:te-tp-id
                  |  +--rw plug-id?                uint32
                  +--rw is-abstract?                      empty
                  +--rw name?                             string
                  +--rw underlay {te-topology-hierarchy}?
                  |  +--rw enabled?                     boolean
                  |  +--rw primary-path
                  |  |  +--rw network-ref?    leafref
                  |  |  +--rw path-element* [path-element-id]
                  |  |     +--rw path-element-id    uint32
                  |  |     +--rw index?             uint32


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                  |  |     +--rw (type)?
                  |  |        +--:(numbered)
                  |  |        |  +--rw numbered-hop
                  |  |        |     +--rw address?    te-types:te-tp-id
                  |  |        |     +--rw hop-type?   te-hop-type
                  |  |        +--:(as-number)
                  |  |        |  +--rw as-number-hop
                  |  |        |     +--rw as-number?   binary
                  |  |        |     +--rw hop-type?    te-hop-type
                  |  |        +--:(unnumbered)
                  |  |        |  +--rw unnumbered-hop
                  |  |        |     +--rw node-id?      te-types:te-
   node-id
                  |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
                  |  |        |     +--rw hop-type?     te-hop-type
                  |  |        +--:(label)
                  |  |        |  +--rw label-hop
                  |  |        |     +--rw value?   rt-types:generalized-
   label
                  |  |        +--:(sid)
                  |  |           +--rw sid-hop
                  |  |              +--rw sid?   rt-types:generalized-
   label
                  |  +--rw backup-path* [index]
                  |  |  +--rw index           uint32
                  |  |  +--rw network-ref?    leafref
                  |  |  +--rw path-element* [path-element-id]
                  |  |     +--rw path-element-id    uint32
                  |  |     +--rw index?             uint32
                  |  |     +--rw (type)?
                  |  |        +--:(numbered)
                  |  |        |  +--rw numbered-hop
                  |  |        |     +--rw address?    te-types:te-tp-id
                  |  |        |     +--rw hop-type?   te-hop-type
                  |  |        +--:(as-number)
                  |  |        |  +--rw as-number-hop
                  |  |        |     +--rw as-number?   binary
                  |  |        |     +--rw hop-type?    te-hop-type
                  |  |        +--:(unnumbered)
                  |  |        |  +--rw unnumbered-hop
                  |  |        |     +--rw node-id?      te-types:te-
   node-id
                  |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
                  |  |        |     +--rw hop-type?     te-hop-type
                  |  |        +--:(label)


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                  |  |        |  +--rw label-hop
                  |  |        |     +--rw value?   rt-types:generalized-
   label
                  |  |        +--:(sid)
                  |  |           +--rw sid-hop
                  |  |              +--rw sid?   rt-types:generalized-
   label
                  |  +--rw protection-type?             identityref
                  |  +--rw tunnel-termination-points
                  |  |  +--rw source?        binary
                  |  |  +--rw destination?   binary
                  |  +--rw tunnels
                  |     +--rw sharing?   boolean
                  |     +--rw tunnel* [tunnel-name]
                  |        +--rw tunnel-name    string
                  |        +--rw sharing?       boolean
                  +--rw admin-status?                     te-types:te-
   admin-status
                  +--rw link-index?                       uint64
                  +--rw administrative-group?             te-
   types:admin-groups
                  +--rw interface-switching-capability* [switching-
   capability encoding]
                  |  +--rw switching-capability    identityref
                  |  +--rw encoding                identityref
                  |  +--rw max-lsp-bandwidth* [priority]
                  |     +--rw priority     uint8
                  |     +--rw bandwidth
                  |        +--rw te-bandwidth
                  |           +--rw (technology)?
                  |              +--:(psc)
                  |              |  +--rw psc?       rt-types:bandwidth-
   ieee-float32
                  |              +--:(otn)
                  |              |  +--rw otn* [rate-type]
                  |              |     +--rw rate-type    identityref
                  |              |     +--rw counter?     uint16
                  |              +--:(lsc)
                  |              |  +--rw wdm* [spectrum slot]
                  |              |     +--rw spectrum    identityref
                  |              |     +--rw slot        int16
                  |              |     +--rw width?      uint16
                  |              +--:(generic)
                  |                 +--rw generic?   te-bandwidth
                  +--rw label-restriction* [inclusive-exclusive label-
   start]
                  |  +--rw inclusive-exclusive    enumeration


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                  |  +--rw label-start            rt-types:generalized-
   label
                  |  +--rw label-end?             rt-types:generalized-
   label
                  |  +--rw range-bitmap?          binary
                  +--rw link-protection-type?             enumeration
                  +--rw max-link-bandwidth
                  |  +--rw te-bandwidth
                  |     +--rw (technology)?
                  |        +--:(psc)
                  |        |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
                  |        +--:(otn)
                  |        |  +--rw otn* [rate-type]
                  |        |     +--rw rate-type    identityref
                  |        |     +--rw counter?     uint16
                  |        +--:(lsc)
                  |        |  +--rw wdm* [spectrum slot]
                  |        |     +--rw spectrum    identityref
                  |        |     +--rw slot        int16
                  |        |     +--rw width?      uint16
                  |        +--:(generic)
                  |           +--rw generic?   te-bandwidth
                  +--rw max-resv-link-bandwidth
                  |  +--rw te-bandwidth
                  |     +--rw (technology)?
                  |        +--:(psc)
                  |        |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
                  |        +--:(otn)
                  |        |  +--rw otn* [rate-type]
                  |        |     +--rw rate-type    identityref
                  |        |     +--rw counter?     uint16
                  |        +--:(lsc)
                  |        |  +--rw wdm* [spectrum slot]
                  |        |     +--rw spectrum    identityref
                  |        |     +--rw slot        int16
                  |        |     +--rw width?      uint16
                  |        +--:(generic)
                  |           +--rw generic?   te-bandwidth
                  +--rw unreserved-bandwidth* [priority]
                  |  +--rw priority     uint8
                  |  +--rw bandwidth
                  |     +--rw te-bandwidth
                  |        +--rw (technology)?
                  |           +--:(psc)



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                  |           |  +--rw psc?       rt-types:bandwidth-
   ieee-float32
                  |           +--:(otn)
                  |           |  +--rw otn* [rate-type]
                  |           |     +--rw rate-type    identityref
                  |           |     +--rw counter?     uint16
                  |           +--:(lsc)
                  |           |  +--rw wdm* [spectrum slot]
                  |           |     +--rw spectrum    identityref
                  |           |     +--rw slot        int16
                  |           |     +--rw width?      uint16
                  |           +--:(generic)
                  |              +--rw generic?   te-bandwidth
                  +--rw te-default-metric?                uint32
                  +--rw te-delay-metric?                  uint32
                  +--rw te-igp-metric?                    uint32
                  +--rw te-srlgs
                  |  +--rw value*   te-types:srlg
                  +--rw te-nsrlgs {nsrlg}?
                     +--rw id*   uint32
   augment /nw:networks/nw:network:
      +--rw provider-id?      te-types:te-global-id
      +--rw client-id?        te-types:te-global-id
      +--rw te-topology-id?   te-types:te-topology-id
      +--rw te!
         +--rw preference?               uint8
         +--rw optimization-criterion?   identityref
         +--rw nsrlg* [id] {nsrlg}?
         |  +--rw id              uint32
         |  +--rw disjointness?   te-types:te-path-disjointness
         +--ro geolocation
            +--ro altitude?    int64
            +--ro latitude?    geographic-coordinate-degree
            +--ro longitude?   geographic-coordinate-degree
   augment /nw:networks/nw:network/nw:node:
      +--rw te-node-id?   te-types:te-node-id
      +--rw te!
         +--rw te-node-template*           leafref {template}?
         +--rw te-node-attributes
         |  +--rw admin-status?            te-types:te-admin-status
         |  +--rw connectivity-matrices
         |  |  +--rw number-of-entries?          uint16
         |  |  +--rw label-restriction* [inclusive-exclusive label-
   start]
         |  |  |  +--rw inclusive-exclusive    enumeration
         |  |  |  +--rw label-start            rt-types:generalized-
   label


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         |  |  |  +--rw label-end?             rt-types:generalized-
   label
         |  |  |  +--rw range-bitmap?          binary
         |  |  +--rw is-allowed?                 boolean
         |  |  +--rw underlay {te-topology-hierarchy}?
         |  |  |  +--rw enabled?                     boolean
         |  |  |  +--rw primary-path
         |  |  |  |  +--rw network-ref?    leafref
         |  |  |  |  +--rw path-element* [path-element-id]
         |  |  |  |     +--rw path-element-id    uint32
         |  |  |  |     +--rw index?             uint32
         |  |  |  |     +--rw (type)?
         |  |  |  |        +--:(numbered)
         |  |  |  |        |  +--rw numbered-hop
         |  |  |  |        |     +--rw address?    te-types:te-tp-id
         |  |  |  |        |     +--rw hop-type?   te-hop-type
         |  |  |  |        +--:(as-number)
         |  |  |  |        |  +--rw as-number-hop
         |  |  |  |        |     +--rw as-number?   binary
         |  |  |  |        |     +--rw hop-type?    te-hop-type
         |  |  |  |        +--:(unnumbered)
         |  |  |  |        |  +--rw unnumbered-hop
         |  |  |  |        |     +--rw node-id?      te-types:te-node-id
         |  |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
         |  |  |  |        |     +--rw hop-type?     te-hop-type
         |  |  |  |        +--:(label)
         |  |  |  |        |  +--rw label-hop
         |  |  |  |        |     +--rw value?   rt-types:generalized-
   label
         |  |  |  |        +--:(sid)
         |  |  |  |           +--rw sid-hop
         |  |  |  |              +--rw sid?   rt-types:generalized-label
         |  |  |  +--rw backup-path* [index]
         |  |  |  |  +--rw index           uint32
         |  |  |  |  +--rw network-ref?    leafref
         |  |  |  |  +--rw path-element* [path-element-id]
         |  |  |  |     +--rw path-element-id    uint32
         |  |  |  |     +--rw index?             uint32
         |  |  |  |     +--rw (type)?
         |  |  |  |        +--:(numbered)
         |  |  |  |        |  +--rw numbered-hop
         |  |  |  |        |     +--rw address?    te-types:te-tp-id
         |  |  |  |        |     +--rw hop-type?   te-hop-type
         |  |  |  |        +--:(as-number)
         |  |  |  |        |  +--rw as-number-hop
         |  |  |  |        |     +--rw as-number?   binary
         |  |  |  |        |     +--rw hop-type?    te-hop-type


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         |  |  |  |        +--:(unnumbered)
         |  |  |  |        |  +--rw unnumbered-hop
         |  |  |  |        |     +--rw node-id?      te-types:te-node-id
         |  |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
         |  |  |  |        |     +--rw hop-type?     te-hop-type
         |  |  |  |        +--:(label)
         |  |  |  |        |  +--rw label-hop
         |  |  |  |        |     +--rw value?   rt-types:generalized-
   label
         |  |  |  |        +--:(sid)
         |  |  |  |           +--rw sid-hop
         |  |  |  |              +--rw sid?   rt-types:generalized-label
         |  |  |  +--rw protection-type?             identityref
         |  |  |  +--rw tunnel-termination-points
         |  |  |  |  +--rw source?        binary
         |  |  |  |  +--rw destination?   binary
         |  |  |  +--rw tunnels
         |  |  |     +--rw sharing?   boolean
         |  |  |     +--rw tunnel* [tunnel-name]
         |  |  |        +--rw tunnel-name    string
         |  |  |        +--rw sharing?       boolean
         |  |  +--rw path-constraints
         |  |  |  +--rw path-metric-bound* [metric-type]
         |  |  |  |  +--rw metric-type    identityref
         |  |  |  |  +--rw upper-bound?   uint64
         |  |  |  +--rw topology-id?         te-types:te-topology-id
         |  |  |  +--rw ignore-overload?     boolean
         |  |  |  +--rw bandwidth-generic
         |  |  |  |  +--rw te-bandwidth
         |  |  |  |     +--rw (technology)?
         |  |  |  |        +--:(psc)
         |  |  |  |        |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
         |  |  |  |        +--:(otn)
         |  |  |  |        |  +--rw otn* [rate-type]
         |  |  |  |        |     +--rw rate-type    identityref
         |  |  |  |        |     +--rw counter?     uint16
         |  |  |  |        +--:(lsc)
         |  |  |  |        |  +--rw wdm* [spectrum slot]
         |  |  |  |        |     +--rw spectrum    identityref
         |  |  |  |        |     +--rw slot        int16
         |  |  |  |        |     +--rw width?      uint16
         |  |  |  |        +--:(generic)
         |  |  |  |           +--rw generic?   te-bandwidth
         |  |  |  +--rw disjointness?        te-types:te-path-
   disjointness
         |  |  |  +--rw setup-priority?      uint8


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         |  |  |  +--rw hold-priority?       uint8
         |  |  |  +--rw signaling-type?      identityref
         |  |  |  +--rw path-affinities
         |  |  |  |  +--rw constraint* [usage]
         |  |  |  |     +--rw usage    identityref
         |  |  |  |     +--rw value?   admin-groups
         |  |  |  +--rw path-srlgs
         |  |  |     +--rw usage?    identityref
         |  |  |     +--rw values*   srlg
         |  |  +--rw optimizations
         |  |  |  +--rw (algorithm)?
         |  |  |     +--:(metric) {path-optimization-metric}?
         |  |  |     |  +--rw optimization-metric* [metric-type]
         |  |  |     |  |  +--rw metric-type    identityref
         |  |  |     |  |  +--rw weight?        uint8
         |  |  |     |  +--rw tiebreakers
         |  |  |     |     +--rw tiebreaker* [tiebreaker-type]
         |  |  |     |        +--rw tiebreaker-type    identityref
         |  |  |     +--:(objective-function) {path-optimization-
   objective-function}?
         |  |  |        +--rw objective-function
         |  |  |           +--rw objective-function-type?   identityref
         |  |  +--ro computed-path-properties
         |  |  |  +--ro path-metric* [metric-type]
         |  |  |  |  +--ro metric-type           identityref
         |  |  |  |  +--ro accumulative-value?   uint64
         |  |  |  +--ro path-affinities
         |  |  |  |  +--ro constraint* [usage]
         |  |  |  |     +--ro usage    identityref
         |  |  |  |     +--ro value?   admin-groups
         |  |  |  +--ro path-srlgs
         |  |  |  |  +--ro usage?    identityref
         |  |  |  |  +--ro values*   srlg
         |  |  |  +--ro path-computed-route-objects
         |  |  |     +--ro path-computed-route-object* [index]
         |  |  |        +--ro index             uint32
         |  |  |        +--ro (type)?
         |  |  |           +--:(numbered)
         |  |  |           |  +--ro numbered-hop
         |  |  |           |     +--ro address?    te-types:te-tp-id
         |  |  |           |     +--ro hop-type?   te-hop-type
         |  |  |           +--:(as-number)
         |  |  |           |  +--ro as-number-hop
         |  |  |           |     +--ro as-number?   binary
         |  |  |           |     +--ro hop-type?    te-hop-type
         |  |  |           +--:(unnumbered)
         |  |  |           |  +--ro unnumbered-hop


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         |  |  |           |     +--ro node-id?      te-types:te-node-id
         |  |  |           |     +--ro link-tp-id?   te-types:te-tp-id
         |  |  |           |     +--ro hop-type?     te-hop-type
         |  |  |           +--:(label)
         |  |  |           |  +--ro label-hop
         |  |  |           |     +--ro value?   rt-types:generalized-
   label
         |  |  |           +--:(sid)
         |  |  |              +--ro sid-hop
         |  |  |                 +--ro sid?   rt-types:generalized-label
         |  |  +--rw connectivity-matrix* [id]
         |  |     +--rw id                          uint32
         |  |     +--rw from
         |  |     |  +--rw tp-ref?              leafref
         |  |     |  +--rw label-restriction* [inclusive-exclusive
   label-start]
         |  |     |     +--rw inclusive-exclusive    enumeration
         |  |     |     +--rw label-start            rt-
   types:generalized-label
         |  |     |     +--rw label-end?             rt-
   types:generalized-label
         |  |     |     +--rw range-bitmap?          binary
         |  |     +--rw to
         |  |     |  +--rw tp-ref?              leafref
         |  |     |  +--rw label-restriction* [inclusive-exclusive
   label-start]
         |  |     |     +--rw inclusive-exclusive    enumeration
         |  |     |     +--rw label-start            rt-
   types:generalized-label
         |  |     |     +--rw label-end?             rt-
   types:generalized-label
         |  |     |     +--rw range-bitmap?          binary
         |  |     +--rw is-allowed?                 boolean
         |  |     +--rw underlay {te-topology-hierarchy}?
         |  |     |  +--rw enabled?                     boolean
         |  |     |  +--rw primary-path
         |  |     |  |  +--rw network-ref?    leafref
         |  |     |  |  +--rw path-element* [path-element-id]
         |  |     |  |     +--rw path-element-id    uint32
         |  |     |  |     +--rw index?             uint32
         |  |     |  |     +--rw (type)?
         |  |     |  |        +--:(numbered)
         |  |     |  |        |  +--rw numbered-hop
         |  |     |  |        |     +--rw address?    te-types:te-tp-id
         |  |     |  |        |     +--rw hop-type?   te-hop-type
         |  |     |  |        +--:(as-number)
         |  |     |  |        |  +--rw as-number-hop


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         |  |     |  |        |     +--rw as-number?   binary
         |  |     |  |        |     +--rw hop-type?    te-hop-type
         |  |     |  |        +--:(unnumbered)
         |  |     |  |        |  +--rw unnumbered-hop
         |  |     |  |        |     +--rw node-id?      te-types:te-
   node-id
         |  |     |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
         |  |     |  |        |     +--rw hop-type?     te-hop-type
         |  |     |  |        +--:(label)
         |  |     |  |        |  +--rw label-hop
         |  |     |  |        |     +--rw value?   rt-types:generalized-
   label
         |  |     |  |        +--:(sid)
         |  |     |  |           +--rw sid-hop
         |  |     |  |              +--rw sid?   rt-types:generalized-
   label
         |  |     |  +--rw backup-path* [index]
         |  |     |  |  +--rw index           uint32
         |  |     |  |  +--rw network-ref?    leafref
         |  |     |  |  +--rw path-element* [path-element-id]
         |  |     |  |     +--rw path-element-id    uint32
         |  |     |  |     +--rw index?             uint32
         |  |     |  |     +--rw (type)?
         |  |     |  |        +--:(numbered)
         |  |     |  |        |  +--rw numbered-hop
         |  |     |  |        |     +--rw address?    te-types:te-tp-id
         |  |     |  |        |     +--rw hop-type?   te-hop-type
         |  |     |  |        +--:(as-number)
         |  |     |  |        |  +--rw as-number-hop
         |  |     |  |        |     +--rw as-number?   binary
         |  |     |  |        |     +--rw hop-type?    te-hop-type
         |  |     |  |        +--:(unnumbered)
         |  |     |  |        |  +--rw unnumbered-hop
         |  |     |  |        |     +--rw node-id?      te-types:te-
   node-id
         |  |     |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
         |  |     |  |        |     +--rw hop-type?     te-hop-type
         |  |     |  |        +--:(label)
         |  |     |  |        |  +--rw label-hop
         |  |     |  |        |     +--rw value?   rt-types:generalized-
   label
         |  |     |  |        +--:(sid)
         |  |     |  |           +--rw sid-hop
         |  |     |  |              +--rw sid?   rt-types:generalized-
   label


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         |  |     |  +--rw protection-type?             identityref
         |  |     |  +--rw tunnel-termination-points
         |  |     |  |  +--rw source?        binary
         |  |     |  |  +--rw destination?   binary
         |  |     |  +--rw tunnels
         |  |     |     +--rw sharing?   boolean
         |  |     |     +--rw tunnel* [tunnel-name]
         |  |     |        +--rw tunnel-name    string
         |  |     |        +--rw sharing?       boolean
         |  |     +--rw path-constraints
         |  |     |  +--rw path-metric-bound* [metric-type]
         |  |     |  |  +--rw metric-type    identityref
         |  |     |  |  +--rw upper-bound?   uint64
         |  |     |  +--rw topology-id?         te-types:te-topology-id
         |  |     |  +--rw ignore-overload?     boolean
         |  |     |  +--rw bandwidth-generic
         |  |     |  |  +--rw te-bandwidth
         |  |     |  |     +--rw (technology)?
         |  |     |  |        +--:(psc)
         |  |     |  |        |  +--rw psc?       rt-types:bandwidth-
   ieee-float32
         |  |     |  |        +--:(otn)
         |  |     |  |        |  +--rw otn* [rate-type]
         |  |     |  |        |     +--rw rate-type    identityref
         |  |     |  |        |     +--rw counter?     uint16
         |  |     |  |        +--:(lsc)
         |  |     |  |        |  +--rw wdm* [spectrum slot]
         |  |     |  |        |     +--rw spectrum    identityref
         |  |     |  |        |     +--rw slot        int16
         |  |     |  |        |     +--rw width?      uint16
         |  |     |  |        +--:(generic)
         |  |     |  |           +--rw generic?   te-bandwidth
         |  |     |  +--rw disjointness?        te-types:te-path-
   disjointness
         |  |     |  +--rw setup-priority?      uint8
         |  |     |  +--rw hold-priority?       uint8
         |  |     |  +--rw signaling-type?      identityref
         |  |     |  +--rw path-affinities
         |  |     |  |  +--rw constraint* [usage]
         |  |     |  |     +--rw usage    identityref
         |  |     |  |     +--rw value?   admin-groups
         |  |     |  +--rw path-srlgs
         |  |     |     +--rw usage?    identityref
         |  |     |     +--rw values*   srlg
         |  |     +--rw optimizations
         |  |     |  +--rw (algorithm)?
         |  |     |     +--:(metric) {path-optimization-metric}?


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         |  |     |     |  +--rw optimization-metric* [metric-type]
         |  |     |     |  |  +--rw metric-type    identityref
         |  |     |     |  |  +--rw weight?        uint8
         |  |     |     |  +--rw tiebreakers
         |  |     |     |     +--rw tiebreaker* [tiebreaker-type]
         |  |     |     |        +--rw tiebreaker-type    identityref
         |  |     |     +--:(objective-function) {path-optimization-
   objective-function}?
         |  |     |        +--rw objective-function
         |  |     |           +--rw objective-function-type?
   identityref
         |  |     +--ro computed-path-properties
         |  |        +--ro path-metric* [metric-type]
         |  |        |  +--ro metric-type           identityref
         |  |        |  +--ro accumulative-value?   uint64
         |  |        +--ro path-affinities
         |  |        |  +--ro constraint* [usage]
         |  |        |     +--ro usage    identityref
         |  |        |     +--ro value?   admin-groups
         |  |        +--ro path-srlgs
         |  |        |  +--ro usage?    identityref
         |  |        |  +--ro values*   srlg
         |  |        +--ro path-computed-route-objects
         |  |           +--ro path-computed-route-object* [index]
         |  |              +--ro index             uint32
         |  |              +--ro (type)?
         |  |                 +--:(numbered)
         |  |                 |  +--ro numbered-hop
         |  |                 |     +--ro address?    te-types:te-tp-id
         |  |                 |     +--ro hop-type?   te-hop-type
         |  |                 +--:(as-number)
         |  |                 |  +--ro as-number-hop
         |  |                 |     +--ro as-number?   binary
         |  |                 |     +--ro hop-type?    te-hop-type
         |  |                 +--:(unnumbered)
         |  |                 |  +--ro unnumbered-hop
         |  |                 |     +--ro node-id?      te-types:te-
   node-id
         |  |                 |     +--ro link-tp-id?   te-types:te-tp-
   id
         |  |                 |     +--ro hop-type?     te-hop-type
         |  |                 +--:(label)
         |  |                 |  +--ro label-hop
         |  |                 |     +--ro value?   rt-types:generalized-
   label
         |  |                 +--:(sid)
         |  |                    +--ro sid-hop


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         |  |                       +--ro sid?   rt-types:generalized-
   label
         |  +--rw domain-id?               uint32
         |  +--rw is-abstract?             empty
         |  +--rw name?                    inet:domain-name
         |  +--rw signaling-address*       inet:ip-address
         |  +--rw underlay-topology {te-topology-hierarchy}?
         |     +--rw network-ref?   leafref
         +--ro oper-status?                te-types:te-oper-status
         +--ro geolocation
         |  +--ro altitude?    int64
         |  +--ro latitude?    geographic-coordinate-degree
         |  +--ro longitude?   geographic-coordinate-degree
         +--ro is-multi-access-dr?         empty
         +--ro information-source?         te-info-source
         +--ro information-source-state
         |  +--ro credibility-preference?    uint16
         |  +--ro logical-network-element?   string
         |  +--ro network-instance?          string
         |  +--ro topology
         |     +--ro node-ref?      leafref
         |     +--ro network-ref?   leafref
         +--ro information-source-entry* [information-source]
         |  +--ro information-source          te-info-source
         |  +--ro information-source-state
         |  |  +--ro credibility-preference?    uint16
         |  |  +--ro logical-network-element?   string
         |  |  +--ro network-instance?          string
         |  |  +--ro topology
         |  |     +--ro node-ref?      leafref
         |  |     +--ro network-ref?   leafref
         |  +--ro connectivity-matrices
         |  |  +--ro number-of-entries?          uint16
         |  |  +--ro label-restriction* [inclusive-exclusive label-
   start]
         |  |  |  +--ro inclusive-exclusive    enumeration
         |  |  |  +--ro label-start            rt-types:generalized-
   label
         |  |  |  +--ro label-end?             rt-types:generalized-
   label
         |  |  |  +--ro range-bitmap?          binary
         |  |  +--ro is-allowed?                 boolean
         |  |  +--ro underlay {te-topology-hierarchy}?
         |  |  |  +--ro enabled?                     boolean
         |  |  |  +--ro primary-path
         |  |  |  |  +--ro network-ref?    leafref
         |  |  |  |  +--ro path-element* [path-element-id]


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         |  |  |  |     +--ro path-element-id    uint32
         |  |  |  |     +--ro index?             uint32
         |  |  |  |     +--ro (type)?
         |  |  |  |        +--:(numbered)
         |  |  |  |        |  +--ro numbered-hop
         |  |  |  |        |     +--ro address?    te-types:te-tp-id
         |  |  |  |        |     +--ro hop-type?   te-hop-type
         |  |  |  |        +--:(as-number)
         |  |  |  |        |  +--ro as-number-hop
         |  |  |  |        |     +--ro as-number?   binary
         |  |  |  |        |     +--ro hop-type?    te-hop-type
         |  |  |  |        +--:(unnumbered)
         |  |  |  |        |  +--ro unnumbered-hop
         |  |  |  |        |     +--ro node-id?      te-types:te-node-id
         |  |  |  |        |     +--ro link-tp-id?   te-types:te-tp-id
         |  |  |  |        |     +--ro hop-type?     te-hop-type
         |  |  |  |        +--:(label)
         |  |  |  |        |  +--ro label-hop
         |  |  |  |        |     +--ro value?   rt-types:generalized-
   label
         |  |  |  |        +--:(sid)
         |  |  |  |           +--ro sid-hop
         |  |  |  |              +--ro sid?   rt-types:generalized-label
         |  |  |  +--ro backup-path* [index]
         |  |  |  |  +--ro index           uint32
         |  |  |  |  +--ro network-ref?    leafref
         |  |  |  |  +--ro path-element* [path-element-id]
         |  |  |  |     +--ro path-element-id    uint32
         |  |  |  |     +--ro index?             uint32
         |  |  |  |     +--ro (type)?
         |  |  |  |        +--:(numbered)
         |  |  |  |        |  +--ro numbered-hop
         |  |  |  |        |     +--ro address?    te-types:te-tp-id
         |  |  |  |        |     +--ro hop-type?   te-hop-type
         |  |  |  |        +--:(as-number)
         |  |  |  |        |  +--ro as-number-hop
         |  |  |  |        |     +--ro as-number?   binary
         |  |  |  |        |     +--ro hop-type?    te-hop-type
         |  |  |  |        +--:(unnumbered)
         |  |  |  |        |  +--ro unnumbered-hop
         |  |  |  |        |     +--ro node-id?      te-types:te-node-id
         |  |  |  |        |     +--ro link-tp-id?   te-types:te-tp-id
         |  |  |  |        |     +--ro hop-type?     te-hop-type
         |  |  |  |        +--:(label)
         |  |  |  |        |  +--ro label-hop
         |  |  |  |        |     +--ro value?   rt-types:generalized-
   label


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         |  |  |  |        +--:(sid)
         |  |  |  |           +--ro sid-hop
         |  |  |  |              +--ro sid?   rt-types:generalized-label
         |  |  |  +--ro protection-type?             identityref
         |  |  |  +--ro tunnel-termination-points
         |  |  |  |  +--ro source?        binary
         |  |  |  |  +--ro destination?   binary
         |  |  |  +--ro tunnels
         |  |  |     +--ro sharing?   boolean
         |  |  |     +--ro tunnel* [tunnel-name]
         |  |  |        +--ro tunnel-name    string
         |  |  |        +--ro sharing?       boolean
         |  |  +--ro path-constraints
         |  |  |  +--ro path-metric-bound* [metric-type]
         |  |  |  |  +--ro metric-type    identityref
         |  |  |  |  +--ro upper-bound?   uint64
         |  |  |  +--ro topology-id?         te-types:te-topology-id
         |  |  |  +--ro ignore-overload?     boolean
         |  |  |  +--ro bandwidth-generic
         |  |  |  |  +--ro te-bandwidth
         |  |  |  |     +--ro (technology)?
         |  |  |  |        +--:(psc)
         |  |  |  |        |  +--ro psc?       rt-types:bandwidth-ieee-
   float32
         |  |  |  |        +--:(otn)
         |  |  |  |        |  +--ro otn* [rate-type]
         |  |  |  |        |     +--ro rate-type    identityref
         |  |  |  |        |     +--ro counter?     uint16
         |  |  |  |        +--:(lsc)
         |  |  |  |        |  +--ro wdm* [spectrum slot]
         |  |  |  |        |     +--ro spectrum    identityref
         |  |  |  |        |     +--ro slot        int16
         |  |  |  |        |     +--ro width?      uint16
         |  |  |  |        +--:(generic)
         |  |  |  |           +--ro generic?   te-bandwidth
         |  |  |  +--ro disjointness?        te-types:te-path-
   disjointness
         |  |  |  +--ro setup-priority?      uint8
         |  |  |  +--ro hold-priority?       uint8
         |  |  |  +--ro signaling-type?      identityref
         |  |  |  +--ro path-affinities
         |  |  |  |  +--ro constraint* [usage]
         |  |  |  |     +--ro usage    identityref
         |  |  |  |     +--ro value?   admin-groups
         |  |  |  +--ro path-srlgs
         |  |  |     +--ro usage?    identityref
         |  |  |     +--ro values*   srlg


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         |  |  +--ro optimizations
         |  |  |  +--ro (algorithm)?
         |  |  |     +--:(metric) {path-optimization-metric}?
         |  |  |     |  +--ro optimization-metric* [metric-type]
         |  |  |     |  |  +--ro metric-type    identityref
         |  |  |     |  |  +--ro weight?        uint8
         |  |  |     |  +--ro tiebreakers
         |  |  |     |     +--ro tiebreaker* [tiebreaker-type]
         |  |  |     |        +--ro tiebreaker-type    identityref
         |  |  |     +--:(objective-function) {path-optimization-
   objective-function}?
         |  |  |        +--ro objective-function
         |  |  |           +--ro objective-function-type?   identityref
         |  |  +--ro computed-path-properties
         |  |  |  +--ro path-metric* [metric-type]
         |  |  |  |  +--ro metric-type           identityref
         |  |  |  |  +--ro accumulative-value?   uint64
         |  |  |  +--ro path-affinities
         |  |  |  |  +--ro constraint* [usage]
         |  |  |  |     +--ro usage    identityref
         |  |  |  |     +--ro value?   admin-groups
         |  |  |  +--ro path-srlgs
         |  |  |  |  +--ro usage?    identityref
         |  |  |  |  +--ro values*   srlg
         |  |  |  +--ro path-computed-route-objects
         |  |  |     +--ro path-computed-route-object* [index]
         |  |  |        +--ro index             uint32
         |  |  |        +--ro (type)?
         |  |  |           +--:(numbered)
         |  |  |           |  +--ro numbered-hop
         |  |  |           |     +--ro address?    te-types:te-tp-id
         |  |  |           |     +--ro hop-type?   te-hop-type
         |  |  |           +--:(as-number)
         |  |  |           |  +--ro as-number-hop
         |  |  |           |     +--ro as-number?   binary
         |  |  |           |     +--ro hop-type?    te-hop-type
         |  |  |           +--:(unnumbered)
         |  |  |           |  +--ro unnumbered-hop
         |  |  |           |     +--ro node-id?      te-types:te-node-id
         |  |  |           |     +--ro link-tp-id?   te-types:te-tp-id
         |  |  |           |     +--ro hop-type?     te-hop-type
         |  |  |           +--:(label)
         |  |  |           |  +--ro label-hop
         |  |  |           |     +--ro value?   rt-types:generalized-
   label
         |  |  |           +--:(sid)
         |  |  |              +--ro sid-hop


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         |  |  |                 +--ro sid?   rt-types:generalized-label
         |  |  +--ro connectivity-matrix* [id]
         |  |     +--ro id                          uint32
         |  |     +--ro from
         |  |     |  +--ro tp-ref?              leafref
         |  |     |  +--ro label-restriction* [inclusive-exclusive
   label-start]
         |  |     |     +--ro inclusive-exclusive    enumeration
         |  |     |     +--ro label-start            rt-
   types:generalized-label
         |  |     |     +--ro label-end?             rt-
   types:generalized-label
         |  |     |     +--ro range-bitmap?          binary
         |  |     +--ro to
         |  |     |  +--ro tp-ref?              leafref
         |  |     |  +--ro label-restriction* [inclusive-exclusive
   label-start]
         |  |     |     +--ro inclusive-exclusive    enumeration
         |  |     |     +--ro label-start            rt-
   types:generalized-label
         |  |     |     +--ro label-end?             rt-
   types:generalized-label
         |  |     |     +--ro range-bitmap?          binary
         |  |     +--ro is-allowed?                 boolean
         |  |     +--ro underlay {te-topology-hierarchy}?
         |  |     |  +--ro enabled?                     boolean
         |  |     |  +--ro primary-path
         |  |     |  |  +--ro network-ref?    leafref
         |  |     |  |  +--ro path-element* [path-element-id]
         |  |     |  |     +--ro path-element-id    uint32
         |  |     |  |     +--ro index?             uint32
         |  |     |  |     +--ro (type)?
         |  |     |  |        +--:(numbered)
         |  |     |  |        |  +--ro numbered-hop
         |  |     |  |        |     +--ro address?    te-types:te-tp-id
         |  |     |  |        |     +--ro hop-type?   te-hop-type
         |  |     |  |        +--:(as-number)
         |  |     |  |        |  +--ro as-number-hop
         |  |     |  |        |     +--ro as-number?   binary
         |  |     |  |        |     +--ro hop-type?    te-hop-type
         |  |     |  |        +--:(unnumbered)
         |  |     |  |        |  +--ro unnumbered-hop
         |  |     |  |        |     +--ro node-id?      te-types:te-
   node-id
         |  |     |  |        |     +--ro link-tp-id?   te-types:te-tp-
   id
         |  |     |  |        |     +--ro hop-type?     te-hop-type


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         |  |     |  |        +--:(label)
         |  |     |  |        |  +--ro label-hop
         |  |     |  |        |     +--ro value?   rt-types:generalized-
   label
         |  |     |  |        +--:(sid)
         |  |     |  |           +--ro sid-hop
         |  |     |  |              +--ro sid?   rt-types:generalized-
   label
         |  |     |  +--ro backup-path* [index]
         |  |     |  |  +--ro index           uint32
         |  |     |  |  +--ro network-ref?    leafref
         |  |     |  |  +--ro path-element* [path-element-id]
         |  |     |  |     +--ro path-element-id    uint32
         |  |     |  |     +--ro index?             uint32
         |  |     |  |     +--ro (type)?
         |  |     |  |        +--:(numbered)
         |  |     |  |        |  +--ro numbered-hop
         |  |     |  |        |     +--ro address?    te-types:te-tp-id
         |  |     |  |        |     +--ro hop-type?   te-hop-type
         |  |     |  |        +--:(as-number)
         |  |     |  |        |  +--ro as-number-hop
         |  |     |  |        |     +--ro as-number?   binary
         |  |     |  |        |     +--ro hop-type?    te-hop-type
         |  |     |  |        +--:(unnumbered)
         |  |     |  |        |  +--ro unnumbered-hop
         |  |     |  |        |     +--ro node-id?      te-types:te-
   node-id
         |  |     |  |        |     +--ro link-tp-id?   te-types:te-tp-
   id
         |  |     |  |        |     +--ro hop-type?     te-hop-type
         |  |     |  |        +--:(label)
         |  |     |  |        |  +--ro label-hop
         |  |     |  |        |     +--ro value?   rt-types:generalized-
   label
         |  |     |  |        +--:(sid)
         |  |     |  |           +--ro sid-hop
         |  |     |  |              +--ro sid?   rt-types:generalized-
   label
         |  |     |  +--ro protection-type?             identityref
         |  |     |  +--ro tunnel-termination-points
         |  |     |  |  +--ro source?        binary
         |  |     |  |  +--ro destination?   binary
         |  |     |  +--ro tunnels
         |  |     |     +--ro sharing?   boolean
         |  |     |     +--ro tunnel* [tunnel-name]
         |  |     |        +--ro tunnel-name    string
         |  |     |        +--ro sharing?       boolean


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         |  |     +--ro path-constraints
         |  |     |  +--ro path-metric-bound* [metric-type]
         |  |     |  |  +--ro metric-type    identityref
         |  |     |  |  +--ro upper-bound?   uint64
         |  |     |  +--ro topology-id?         te-types:te-topology-id
         |  |     |  +--ro ignore-overload?     boolean
         |  |     |  +--ro bandwidth-generic
         |  |     |  |  +--ro te-bandwidth
         |  |     |  |     +--ro (technology)?
         |  |     |  |        +--:(psc)
         |  |     |  |        |  +--ro psc?       rt-types:bandwidth-
   ieee-float32
         |  |     |  |        +--:(otn)
         |  |     |  |        |  +--ro otn* [rate-type]
         |  |     |  |        |     +--ro rate-type    identityref
         |  |     |  |        |     +--ro counter?     uint16
         |  |     |  |        +--:(lsc)
         |  |     |  |        |  +--ro wdm* [spectrum slot]
         |  |     |  |        |     +--ro spectrum    identityref
         |  |     |  |        |     +--ro slot        int16
         |  |     |  |        |     +--ro width?      uint16
         |  |     |  |        +--:(generic)
         |  |     |  |           +--ro generic?   te-bandwidth
         |  |     |  +--ro disjointness?        te-types:te-path-
   disjointness
         |  |     |  +--ro setup-priority?      uint8
         |  |     |  +--ro hold-priority?       uint8
         |  |     |  +--ro signaling-type?      identityref
         |  |     |  +--ro path-affinities
         |  |     |  |  +--ro constraint* [usage]
         |  |     |  |     +--ro usage    identityref
         |  |     |  |     +--ro value?   admin-groups
         |  |     |  +--ro path-srlgs
         |  |     |     +--ro usage?    identityref
         |  |     |     +--ro values*   srlg
         |  |     +--ro optimizations
         |  |     |  +--ro (algorithm)?
         |  |     |     +--:(metric) {path-optimization-metric}?
         |  |     |     |  +--ro optimization-metric* [metric-type]
         |  |     |     |  |  +--ro metric-type    identityref
         |  |     |     |  |  +--ro weight?        uint8
         |  |     |     |  +--ro tiebreakers
         |  |     |     |     +--ro tiebreaker* [tiebreaker-type]
         |  |     |     |        +--ro tiebreaker-type    identityref
         |  |     |     +--:(objective-function) {path-optimization-
   objective-function}?
         |  |     |        +--ro objective-function


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         |  |     |           +--ro objective-function-type?
   identityref
         |  |     +--ro computed-path-properties
         |  |        +--ro path-metric* [metric-type]
         |  |        |  +--ro metric-type           identityref
         |  |        |  +--ro accumulative-value?   uint64
         |  |        +--ro path-affinities
         |  |        |  +--ro constraint* [usage]
         |  |        |     +--ro usage    identityref
         |  |        |     +--ro value?   admin-groups
         |  |        +--ro path-srlgs
         |  |        |  +--ro usage?    identityref
         |  |        |  +--ro values*   srlg
         |  |        +--ro path-computed-route-objects
         |  |           +--ro path-computed-route-object* [index]
         |  |              +--ro index             uint32
         |  |              +--ro (type)?
         |  |                 +--:(numbered)
         |  |                 |  +--ro numbered-hop
         |  |                 |     +--ro address?    te-types:te-tp-id
         |  |                 |     +--ro hop-type?   te-hop-type
         |  |                 +--:(as-number)
         |  |                 |  +--ro as-number-hop
         |  |                 |     +--ro as-number?   binary
         |  |                 |     +--ro hop-type?    te-hop-type
         |  |                 +--:(unnumbered)
         |  |                 |  +--ro unnumbered-hop
         |  |                 |     +--ro node-id?      te-types:te-
   node-id
         |  |                 |     +--ro link-tp-id?   te-types:te-tp-
   id
         |  |                 |     +--ro hop-type?     te-hop-type
         |  |                 +--:(label)
         |  |                 |  +--ro label-hop
         |  |                 |     +--ro value?   rt-types:generalized-
   label
         |  |                 +--:(sid)
         |  |                    +--ro sid-hop
         |  |                       +--ro sid?   rt-types:generalized-
   label
         |  +--ro domain-id?                  uint32
         |  +--ro is-abstract?                empty
         |  +--ro name?                       inet:domain-name
         |  +--ro signaling-address*          inet:ip-address
         |  +--ro underlay-topology {te-topology-hierarchy}?
         |     +--ro network-ref?   leafref
         +--ro statistics


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         |  +--ro discontinuity-time           yang:date-and-time
         |  +--ro node
         |  |  +--ro disables?             yang:counter32
         |  |  +--ro enables?              yang:counter32
         |  |  +--ro maintenance-sets?     yang:counter32
         |  |  +--ro maintenance-clears?   yang:counter32
         |  |  +--ro modifies?             yang:counter32
         |  +--ro connectivity-matrix-entry
         |     +--ro creates?    yang:counter32
         |     +--ro deletes?    yang:counter32
         |     +--ro disables?   yang:counter32
         |     +--ro enables?    yang:counter32
         |     +--ro modifies?   yang:counter32
         +--rw tunnel-termination-point* [tunnel-tp-id]
            +--rw tunnel-tp-id                           binary
            +--rw admin-status?                          te-types:te-
   admin-status
            +--rw name?                                  string
            +--rw switching-capability?                  identityref
            +--rw encoding?                              identityref
            +--rw inter-layer-lock-id*                   uint32
            +--rw protection-type?                       identityref
            +--rw client-layer-adaptation
            |  +--rw switching-capability* [switching-capability
   encoding]
            |     +--rw switching-capability    identityref
            |     +--rw encoding                identityref
            |     +--rw bandwidth
            |        +--rw te-bandwidth
            |           +--rw (technology)?
            |              +--:(psc)
            |              |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
            |              +--:(otn)
            |              |  +--rw otn* [rate-type]
            |              |     +--rw rate-type    identityref
            |              |     +--rw counter?     uint16
            |              +--:(lsc)
            |              |  +--rw wdm* [spectrum slot]
            |              |     +--rw spectrum    identityref
            |              |     +--rw slot        int16
            |              |     +--rw width?      uint16
            |              +--:(generic)
            |                 +--rw generic?   te-bandwidth
            +--rw local-link-connectivities
            |  +--rw number-of-entries?          uint16



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            |  +--rw label-restriction* [inclusive-exclusive label-
   start]
            |  |  +--rw inclusive-exclusive    enumeration
            |  |  +--rw label-start            rt-types:generalized-
   label
            |  |  +--rw label-end?             rt-types:generalized-
   label
            |  |  +--rw range-bitmap?          binary
            |  +--rw is-allowed?                 boolean
            |  +--rw underlay {te-topology-hierarchy}?
            |  |  +--rw enabled?                     boolean
            |  |  +--rw primary-path
            |  |  |  +--rw network-ref?    leafref
            |  |  |  +--rw path-element* [path-element-id]
            |  |  |     +--rw path-element-id    uint32
            |  |  |     +--rw index?             uint32
            |  |  |     +--rw (type)?
            |  |  |        +--:(numbered)
            |  |  |        |  +--rw numbered-hop
            |  |  |        |     +--rw address?    te-types:te-tp-id
            |  |  |        |     +--rw hop-type?   te-hop-type
            |  |  |        +--:(as-number)
            |  |  |        |  +--rw as-number-hop
            |  |  |        |     +--rw as-number?   binary
            |  |  |        |     +--rw hop-type?    te-hop-type
            |  |  |        +--:(unnumbered)
            |  |  |        |  +--rw unnumbered-hop
            |  |  |        |     +--rw node-id?      te-types:te-node-id
            |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
            |  |  |        |     +--rw hop-type?     te-hop-type
            |  |  |        +--:(label)
            |  |  |        |  +--rw label-hop
            |  |  |        |     +--rw value?   rt-types:generalized-
   label
            |  |  |        +--:(sid)
            |  |  |           +--rw sid-hop
            |  |  |              +--rw sid?   rt-types:generalized-label
            |  |  +--rw backup-path* [index]
            |  |  |  +--rw index           uint32
            |  |  |  +--rw network-ref?    leafref
            |  |  |  +--rw path-element* [path-element-id]
            |  |  |     +--rw path-element-id    uint32
            |  |  |     +--rw index?             uint32
            |  |  |     +--rw (type)?
            |  |  |        +--:(numbered)
            |  |  |        |  +--rw numbered-hop
            |  |  |        |     +--rw address?    te-types:te-tp-id


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            |  |  |        |     +--rw hop-type?   te-hop-type
            |  |  |        +--:(as-number)
            |  |  |        |  +--rw as-number-hop
            |  |  |        |     +--rw as-number?   binary
            |  |  |        |     +--rw hop-type?    te-hop-type
            |  |  |        +--:(unnumbered)
            |  |  |        |  +--rw unnumbered-hop
            |  |  |        |     +--rw node-id?      te-types:te-node-id
            |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
            |  |  |        |     +--rw hop-type?     te-hop-type
            |  |  |        +--:(label)
            |  |  |        |  +--rw label-hop
            |  |  |        |     +--rw value?   rt-types:generalized-
   label
            |  |  |        +--:(sid)
            |  |  |           +--rw sid-hop
            |  |  |              +--rw sid?   rt-types:generalized-label
            |  |  +--rw protection-type?             identityref
            |  |  +--rw tunnel-termination-points
            |  |  |  +--rw source?        binary
            |  |  |  +--rw destination?   binary
            |  |  +--rw tunnels
            |  |     +--rw sharing?   boolean
            |  |     +--rw tunnel* [tunnel-name]
            |  |        +--rw tunnel-name    string
            |  |        +--rw sharing?       boolean
            |  +--rw path-constraints
            |  |  +--rw path-metric-bound* [metric-type]
            |  |  |  +--rw metric-type    identityref
            |  |  |  +--rw upper-bound?   uint64
            |  |  +--rw topology-id?         te-types:te-topology-id
            |  |  +--rw ignore-overload?     boolean
            |  |  +--rw bandwidth-generic
            |  |  |  +--rw te-bandwidth
            |  |  |     +--rw (technology)?
            |  |  |        +--:(psc)
            |  |  |        |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
            |  |  |        +--:(otn)
            |  |  |        |  +--rw otn* [rate-type]
            |  |  |        |     +--rw rate-type    identityref
            |  |  |        |     +--rw counter?     uint16
            |  |  |        +--:(lsc)
            |  |  |        |  +--rw wdm* [spectrum slot]
            |  |  |        |     +--rw spectrum    identityref
            |  |  |        |     +--rw slot        int16
            |  |  |        |     +--rw width?      uint16


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            |  |  |        +--:(generic)
            |  |  |           +--rw generic?   te-bandwidth
            |  |  +--rw disjointness?        te-types:te-path-
   disjointness
            |  |  +--rw setup-priority?      uint8
            |  |  +--rw hold-priority?       uint8
            |  |  +--rw signaling-type?      identityref
            |  |  +--rw path-affinities
            |  |  |  +--rw constraint* [usage]
            |  |  |     +--rw usage    identityref
            |  |  |     +--rw value?   admin-groups
            |  |  +--rw path-srlgs
            |  |     +--rw usage?    identityref
            |  |     +--rw values*   srlg
            |  +--rw optimizations
            |  |  +--rw (algorithm)?
            |  |     +--:(metric) {path-optimization-metric}?
            |  |     |  +--rw optimization-metric* [metric-type]
            |  |     |  |  +--rw metric-type    identityref
            |  |     |  |  +--rw weight?        uint8
            |  |     |  +--rw tiebreakers
            |  |     |     +--rw tiebreaker* [tiebreaker-type]
            |  |     |        +--rw tiebreaker-type    identityref
            |  |     +--:(objective-function) {path-optimization-
   objective-function}?
            |  |        +--rw objective-function
            |  |           +--rw objective-function-type?   identityref
            |  +--ro computed-path-properties
            |  |  +--ro path-metric* [metric-type]
            |  |  |  +--ro metric-type           identityref
            |  |  |  +--ro accumulative-value?   uint64
            |  |  +--ro path-affinities
            |  |  |  +--ro constraint* [usage]
            |  |  |     +--ro usage    identityref
            |  |  |     +--ro value?   admin-groups
            |  |  +--ro path-srlgs
            |  |  |  +--ro usage?    identityref
            |  |  |  +--ro values*   srlg
            |  |  +--ro path-computed-route-objects
            |  |     +--ro path-computed-route-object* [index]
            |  |        +--ro index             uint32
            |  |        +--ro (type)?
            |  |           +--:(numbered)
            |  |           |  +--ro numbered-hop
            |  |           |     +--ro address?    te-types:te-tp-id
            |  |           |     +--ro hop-type?   te-hop-type
            |  |           +--:(as-number)


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            |  |           |  +--ro as-number-hop
            |  |           |     +--ro as-number?   binary
            |  |           |     +--ro hop-type?    te-hop-type
            |  |           +--:(unnumbered)
            |  |           |  +--ro unnumbered-hop
            |  |           |     +--ro node-id?      te-types:te-node-id
            |  |           |     +--ro link-tp-id?   te-types:te-tp-id
            |  |           |     +--ro hop-type?     te-hop-type
            |  |           +--:(label)
            |  |           |  +--ro label-hop
            |  |           |     +--ro value?   rt-types:generalized-
   label
            |  |           +--:(sid)
            |  |              +--ro sid-hop
            |  |                 +--ro sid?   rt-types:generalized-label
            |  +--rw local-link-connectivity* [link-tp-ref]
            |     +--rw link-tp-ref                 leafref
            |     +--rw label-restriction* [inclusive-exclusive label-
   start]
            |     |  +--rw inclusive-exclusive    enumeration
            |     |  +--rw label-start            rt-types:generalized-
   label
            |     |  +--rw label-end?             rt-types:generalized-
   label
            |     |  +--rw range-bitmap?          binary
            |     +--rw is-allowed?                 boolean
            |     +--rw underlay {te-topology-hierarchy}?
            |     |  +--rw enabled?                     boolean
            |     |  +--rw primary-path
            |     |  |  +--rw network-ref?    leafref
            |     |  |  +--rw path-element* [path-element-id]
            |     |  |     +--rw path-element-id    uint32
            |     |  |     +--rw index?             uint32
            |     |  |     +--rw (type)?
            |     |  |        +--:(numbered)
            |     |  |        |  +--rw numbered-hop
            |     |  |        |     +--rw address?    te-types:te-tp-id
            |     |  |        |     +--rw hop-type?   te-hop-type
            |     |  |        +--:(as-number)
            |     |  |        |  +--rw as-number-hop
            |     |  |        |     +--rw as-number?   binary
            |     |  |        |     +--rw hop-type?    te-hop-type
            |     |  |        +--:(unnumbered)
            |     |  |        |  +--rw unnumbered-hop
            |     |  |        |     +--rw node-id?      te-types:te-
   node-id



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            |     |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
            |     |  |        |     +--rw hop-type?     te-hop-type
            |     |  |        +--:(label)
            |     |  |        |  +--rw label-hop
            |     |  |        |     +--rw value?   rt-types:generalized-
   label
            |     |  |        +--:(sid)
            |     |  |           +--rw sid-hop
            |     |  |              +--rw sid?   rt-types:generalized-
   label
            |     |  +--rw backup-path* [index]
            |     |  |  +--rw index           uint32
            |     |  |  +--rw network-ref?    leafref
            |     |  |  +--rw path-element* [path-element-id]
            |     |  |     +--rw path-element-id    uint32
            |     |  |     +--rw index?             uint32
            |     |  |     +--rw (type)?
            |     |  |        +--:(numbered)
            |     |  |        |  +--rw numbered-hop
            |     |  |        |     +--rw address?    te-types:te-tp-id
            |     |  |        |     +--rw hop-type?   te-hop-type
            |     |  |        +--:(as-number)
            |     |  |        |  +--rw as-number-hop
            |     |  |        |     +--rw as-number?   binary
            |     |  |        |     +--rw hop-type?    te-hop-type
            |     |  |        +--:(unnumbered)
            |     |  |        |  +--rw unnumbered-hop
            |     |  |        |     +--rw node-id?      te-types:te-
   node-id
            |     |  |        |     +--rw link-tp-id?   te-types:te-tp-
   id
            |     |  |        |     +--rw hop-type?     te-hop-type
            |     |  |        +--:(label)
            |     |  |        |  +--rw label-hop
            |     |  |        |     +--rw value?   rt-types:generalized-
   label
            |     |  |        +--:(sid)
            |     |  |           +--rw sid-hop
            |     |  |              +--rw sid?   rt-types:generalized-
   label
            |     |  +--rw protection-type?             identityref
            |     |  +--rw tunnel-termination-points
            |     |  |  +--rw source?        binary
            |     |  |  +--rw destination?   binary
            |     |  +--rw tunnels
            |     |     +--rw sharing?   boolean


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            |     |     +--rw tunnel* [tunnel-name]
            |     |        +--rw tunnel-name    string
            |     |        +--rw sharing?       boolean
            |     +--rw path-constraints
            |     |  +--rw path-metric-bound* [metric-type]
            |     |  |  +--rw metric-type    identityref
            |     |  |  +--rw upper-bound?   uint64
            |     |  +--rw topology-id?         te-types:te-topology-id
            |     |  +--rw ignore-overload?     boolean
            |     |  +--rw bandwidth-generic
            |     |  |  +--rw te-bandwidth
            |     |  |     +--rw (technology)?
            |     |  |        +--:(psc)
            |     |  |        |  +--rw psc?       rt-types:bandwidth-
   ieee-float32
            |     |  |        +--:(otn)
            |     |  |        |  +--rw otn* [rate-type]
            |     |  |        |     +--rw rate-type    identityref
            |     |  |        |     +--rw counter?     uint16
            |     |  |        +--:(lsc)
            |     |  |        |  +--rw wdm* [spectrum slot]
            |     |  |        |     +--rw spectrum    identityref
            |     |  |        |     +--rw slot        int16
            |     |  |        |     +--rw width?      uint16
            |     |  |        +--:(generic)
            |     |  |           +--rw generic?   te-bandwidth
            |     |  +--rw disjointness?        te-types:te-path-
   disjointness
            |     |  +--rw setup-priority?      uint8
            |     |  +--rw hold-priority?       uint8
            |     |  +--rw signaling-type?      identityref
            |     |  +--rw path-affinities
            |     |  |  +--rw constraint* [usage]
            |     |  |     +--rw usage    identityref
            |     |  |     +--rw value?   admin-groups
            |     |  +--rw path-srlgs
            |     |     +--rw usage?    identityref
            |     |     +--rw values*   srlg
            |     +--rw optimizations
            |     |  +--rw (algorithm)?
            |     |     +--:(metric) {path-optimization-metric}?
            |     |     |  +--rw optimization-metric* [metric-type]
            |     |     |  |  +--rw metric-type    identityref
            |     |     |  |  +--rw weight?        uint8
            |     |     |  +--rw tiebreakers
            |     |     |     +--rw tiebreaker* [tiebreaker-type]
            |     |     |        +--rw tiebreaker-type    identityref


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            |     |     +--:(objective-function) {path-optimization-
   objective-function}?
            |     |        +--rw objective-function
            |     |           +--rw objective-function-type?
   identityref
            |     +--ro computed-path-properties
            |        +--ro path-metric* [metric-type]
            |        |  +--ro metric-type           identityref
            |        |  +--ro accumulative-value?   uint64
            |        +--ro path-affinities
            |        |  +--ro constraint* [usage]
            |        |     +--ro usage    identityref
            |        |     +--ro value?   admin-groups
            |        +--ro path-srlgs
            |        |  +--ro usage?    identityref
            |        |  +--ro values*   srlg
            |        +--ro path-computed-route-objects
            |           +--ro path-computed-route-object* [index]
            |              +--ro index             uint32
            |              +--ro (type)?
            |                 +--:(numbered)
            |                 |  +--ro numbered-hop
            |                 |     +--ro address?    te-types:te-tp-id
            |                 |     +--ro hop-type?   te-hop-type
            |                 +--:(as-number)
            |                 |  +--ro as-number-hop
            |                 |     +--ro as-number?   binary
            |                 |     +--ro hop-type?    te-hop-type
            |                 +--:(unnumbered)
            |                 |  +--ro unnumbered-hop
            |                 |     +--ro node-id?      te-types:te-
   node-id
            |                 |     +--ro link-tp-id?   te-types:te-tp-
   id
            |                 |     +--ro hop-type?     te-hop-type
            |                 +--:(label)
            |                 |  +--ro label-hop
            |                 |     +--ro value?   rt-types:generalized-
   label
            |                 +--:(sid)
            |                    +--ro sid-hop
            |                       +--ro sid?   rt-types:generalized-
   label
            +--ro oper-status?                           te-types:te-
   oper-status
            +--ro geolocation
            |  +--ro altitude?    int64


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            |  +--ro latitude?    geographic-coordinate-degree
            |  +--ro longitude?   geographic-coordinate-degree
            +--ro statistics
            |  +--ro discontinuity-time          yang:date-and-time
            |  +--ro tunnel-termination-point
            |  |  +--ro disables?             yang:counter32
            |  |  +--ro enables?              yang:counter32
            |  |  +--ro maintenance-clears?   yang:counter32
            |  |  +--ro maintenance-sets?     yang:counter32
            |  |  +--ro modifies?             yang:counter32
            |  |  +--ro downs?                yang:counter32
            |  |  +--ro ups?                  yang:counter32
            |  |  +--ro in-service-clears?    yang:counter32
            |  |  +--ro in-service-sets?      yang:counter32
            |  +--ro local-link-connectivity
            |     +--ro creates?    yang:counter32
            |     +--ro deletes?    yang:counter32
            |     +--ro disables?   yang:counter32
            |     +--ro enables?    yang:counter32
            |     +--ro modifies?   yang:counter32
            +--rw supporting-tunnel-termination-point* [node-ref tunnel-
   tp-ref]
               +--rw node-ref         inet:uri
               +--rw tunnel-tp-ref    binary
   augment /nw:networks/nw:network/nt:link:
      +--rw te!
         +--rw (bundle-stack-level)?
         |  +--:(bundle)
         |  |  +--rw bundled-links
         |  |     +--rw bundled-link* [sequence]
         |  |        +--rw sequence      uint32
         |  |        +--rw src-tp-ref?   leafref
         |  |        +--rw des-tp-ref?   leafref
         |  +--:(component)
         |     +--rw component-links
         |        +--rw component-link* [sequence]
         |           +--rw sequence             uint32
         |           +--rw src-interface-ref?   string
         |           +--rw des-interface-ref?   string
         +--rw te-link-template*           leafref {template}?
         +--rw te-link-attributes
         |  +--rw access-type?                      te-types:te-link-
   access-type
         |  +--rw external-domain
         |  |  +--rw network-ref?            leafref
         |  |  +--rw remote-te-node-id?      te-types:te-node-id
         |  |  +--rw remote-te-link-tp-id?   te-types:te-tp-id


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         |  |  +--rw plug-id?                uint32
         |  +--rw is-abstract?                      empty
         |  +--rw name?                             string
         |  +--rw underlay {te-topology-hierarchy}?
         |  |  +--rw enabled?                     boolean
         |  |  +--rw primary-path
         |  |  |  +--rw network-ref?    leafref
         |  |  |  +--rw path-element* [path-element-id]
         |  |  |     +--rw path-element-id    uint32
         |  |  |     +--rw index?             uint32
         |  |  |     +--rw (type)?
         |  |  |        +--:(numbered)
         |  |  |        |  +--rw numbered-hop
         |  |  |        |     +--rw address?    te-types:te-tp-id
         |  |  |        |     +--rw hop-type?   te-hop-type
         |  |  |        +--:(as-number)
         |  |  |        |  +--rw as-number-hop
         |  |  |        |     +--rw as-number?   binary
         |  |  |        |     +--rw hop-type?    te-hop-type
         |  |  |        +--:(unnumbered)
         |  |  |        |  +--rw unnumbered-hop
         |  |  |        |     +--rw node-id?      te-types:te-node-id
         |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
         |  |  |        |     +--rw hop-type?     te-hop-type
         |  |  |        +--:(label)
         |  |  |        |  +--rw label-hop
         |  |  |        |     +--rw value?   rt-types:generalized-label
         |  |  |        +--:(sid)
         |  |  |           +--rw sid-hop
         |  |  |              +--rw sid?   rt-types:generalized-label
         |  |  +--rw backup-path* [index]
         |  |  |  +--rw index           uint32
         |  |  |  +--rw network-ref?    leafref
         |  |  |  +--rw path-element* [path-element-id]
         |  |  |     +--rw path-element-id    uint32
         |  |  |     +--rw index?             uint32
         |  |  |     +--rw (type)?
         |  |  |        +--:(numbered)
         |  |  |        |  +--rw numbered-hop
         |  |  |        |     +--rw address?    te-types:te-tp-id
         |  |  |        |     +--rw hop-type?   te-hop-type
         |  |  |        +--:(as-number)
         |  |  |        |  +--rw as-number-hop
         |  |  |        |     +--rw as-number?   binary
         |  |  |        |     +--rw hop-type?    te-hop-type
         |  |  |        +--:(unnumbered)
         |  |  |        |  +--rw unnumbered-hop


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         |  |  |        |     +--rw node-id?      te-types:te-node-id
         |  |  |        |     +--rw link-tp-id?   te-types:te-tp-id
         |  |  |        |     +--rw hop-type?     te-hop-type
         |  |  |        +--:(label)
         |  |  |        |  +--rw label-hop
         |  |  |        |     +--rw value?   rt-types:generalized-label
         |  |  |        +--:(sid)
         |  |  |           +--rw sid-hop
         |  |  |              +--rw sid?   rt-types:generalized-label
         |  |  +--rw protection-type?             identityref
         |  |  +--rw tunnel-termination-points
         |  |  |  +--rw source?        binary
         |  |  |  +--rw destination?   binary
         |  |  +--rw tunnels
         |  |     +--rw sharing?   boolean
         |  |     +--rw tunnel* [tunnel-name]
         |  |        +--rw tunnel-name    string
         |  |        +--rw sharing?       boolean
         |  +--rw admin-status?                     te-types:te-admin-
   status
         |  +--rw link-index?                       uint64
         |  +--rw administrative-group?             te-types:admin-
   groups
         |  +--rw interface-switching-capability* [switching-capability
   encoding]
         |  |  +--rw switching-capability    identityref
         |  |  +--rw encoding                identityref
         |  |  +--rw max-lsp-bandwidth* [priority]
         |  |     +--rw priority     uint8
         |  |     +--rw bandwidth
         |  |        +--rw te-bandwidth
         |  |           +--rw (technology)?
         |  |              +--:(psc)
         |  |              |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
         |  |              +--:(otn)
         |  |              |  +--rw otn* [rate-type]
         |  |              |     +--rw rate-type    identityref
         |  |              |     +--rw counter?     uint16
         |  |              +--:(lsc)
         |  |              |  +--rw wdm* [spectrum slot]
         |  |              |     +--rw spectrum    identityref
         |  |              |     +--rw slot        int16
         |  |              |     +--rw width?      uint16
         |  |              +--:(generic)
         |  |                 +--rw generic?   te-bandwidth
         |  +--rw label-restriction* [inclusive-exclusive label-start]


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         |  |  +--rw inclusive-exclusive    enumeration
         |  |  +--rw label-start            rt-types:generalized-label
         |  |  +--rw label-end?             rt-types:generalized-label
         |  |  +--rw range-bitmap?          binary
         |  +--rw link-protection-type?             enumeration
         |  +--rw max-link-bandwidth
         |  |  +--rw te-bandwidth
         |  |     +--rw (technology)?
         |  |        +--:(psc)
         |  |        |  +--rw psc?       rt-types:bandwidth-ieee-float32
         |  |        +--:(otn)
         |  |        |  +--rw otn* [rate-type]
         |  |        |     +--rw rate-type    identityref
         |  |        |     +--rw counter?     uint16
         |  |        +--:(lsc)
         |  |        |  +--rw wdm* [spectrum slot]
         |  |        |     +--rw spectrum    identityref
         |  |        |     +--rw slot        int16
         |  |        |     +--rw width?      uint16
         |  |        +--:(generic)
         |  |           +--rw generic?   te-bandwidth
         |  +--rw max-resv-link-bandwidth
         |  |  +--rw te-bandwidth
         |  |     +--rw (technology)?
         |  |        +--:(psc)
         |  |        |  +--rw psc?       rt-types:bandwidth-ieee-float32
         |  |        +--:(otn)
         |  |        |  +--rw otn* [rate-type]
         |  |        |     +--rw rate-type    identityref
         |  |        |     +--rw counter?     uint16
         |  |        +--:(lsc)
         |  |        |  +--rw wdm* [spectrum slot]
         |  |        |     +--rw spectrum    identityref
         |  |        |     +--rw slot        int16
         |  |        |     +--rw width?      uint16
         |  |        +--:(generic)
         |  |           +--rw generic?   te-bandwidth
         |  +--rw unreserved-bandwidth* [priority]
         |  |  +--rw priority     uint8
         |  |  +--rw bandwidth
         |  |     +--rw te-bandwidth
         |  |        +--rw (technology)?
         |  |           +--:(psc)
         |  |           |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
         |  |           +--:(otn)
         |  |           |  +--rw otn* [rate-type]


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         |  |           |     +--rw rate-type    identityref
         |  |           |     +--rw counter?     uint16
         |  |           +--:(lsc)
         |  |           |  +--rw wdm* [spectrum slot]
         |  |           |     +--rw spectrum    identityref
         |  |           |     +--rw slot        int16
         |  |           |     +--rw width?      uint16
         |  |           +--:(generic)
         |  |              +--rw generic?   te-bandwidth
         |  +--rw te-default-metric?                uint32
         |  +--rw te-delay-metric?                  uint32
         |  +--rw te-igp-metric?                    uint32
         |  +--rw te-srlgs
         |  |  +--rw value*   te-types:srlg
         |  +--rw te-nsrlgs {nsrlg}?
         |     +--rw id*   uint32
         +--ro oper-status?                te-types:te-oper-status
         +--ro is-transitional?            empty
         +--ro information-source?         te-info-source
         +--ro information-source-state
         |  +--ro credibility-preference?    uint16
         |  +--ro logical-network-element?   string
         |  +--ro network-instance?          string
         |  +--ro topology
         |     +--ro link-ref?      leafref
         |     +--ro network-ref?   leafref
         +--ro information-source-entry* [information-source]
         |  +--ro information-source                te-info-source
         |  +--ro information-source-state
         |  |  +--ro credibility-preference?    uint16
         |  |  +--ro logical-network-element?   string
         |  |  +--ro network-instance?          string
         |  |  +--ro topology
         |  |     +--ro link-ref?      leafref
         |  |     +--ro network-ref?   leafref
         |  +--ro link-index?                       uint64
         |  +--ro administrative-group?             te-types:admin-
   groups
         |  +--ro interface-switching-capability* [switching-capability
   encoding]
         |  |  +--ro switching-capability    identityref
         |  |  +--ro encoding                identityref
         |  |  +--ro max-lsp-bandwidth* [priority]
         |  |     +--ro priority     uint8
         |  |     +--ro bandwidth
         |  |        +--ro te-bandwidth
         |  |           +--ro (technology)?


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         |  |              +--:(psc)
         |  |              |  +--ro psc?       rt-types:bandwidth-ieee-
   float32
         |  |              +--:(otn)
         |  |              |  +--ro otn* [rate-type]
         |  |              |     +--ro rate-type    identityref
         |  |              |     +--ro counter?     uint16
         |  |              +--:(lsc)
         |  |              |  +--ro wdm* [spectrum slot]
         |  |              |     +--ro spectrum    identityref
         |  |              |     +--ro slot        int16
         |  |              |     +--ro width?      uint16
         |  |              +--:(generic)
         |  |                 +--ro generic?   te-bandwidth
         |  +--ro label-restriction* [inclusive-exclusive label-start]
         |  |  +--ro inclusive-exclusive    enumeration
         |  |  +--ro label-start            rt-types:generalized-label
         |  |  +--ro label-end?             rt-types:generalized-label
         |  |  +--ro range-bitmap?          binary
         |  +--ro link-protection-type?             enumeration
         |  +--ro max-link-bandwidth
         |  |  +--ro te-bandwidth
         |  |     +--ro (technology)?
         |  |        +--:(psc)
         |  |        |  +--ro psc?       rt-types:bandwidth-ieee-float32
         |  |        +--:(otn)
         |  |        |  +--ro otn* [rate-type]
         |  |        |     +--ro rate-type    identityref
         |  |        |     +--ro counter?     uint16
         |  |        +--:(lsc)
         |  |        |  +--ro wdm* [spectrum slot]
         |  |        |     +--ro spectrum    identityref
         |  |        |     +--ro slot        int16
         |  |        |     +--ro width?      uint16
         |  |        +--:(generic)
         |  |           +--ro generic?   te-bandwidth
         |  +--ro max-resv-link-bandwidth
         |  |  +--ro te-bandwidth
         |  |     +--ro (technology)?
         |  |        +--:(psc)
         |  |        |  +--ro psc?       rt-types:bandwidth-ieee-float32
         |  |        +--:(otn)
         |  |        |  +--ro otn* [rate-type]
         |  |        |     +--ro rate-type    identityref
         |  |        |     +--ro counter?     uint16
         |  |        +--:(lsc)
         |  |        |  +--ro wdm* [spectrum slot]


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         |  |        |     +--ro spectrum    identityref
         |  |        |     +--ro slot        int16
         |  |        |     +--ro width?      uint16
         |  |        +--:(generic)
         |  |           +--ro generic?   te-bandwidth
         |  +--ro unreserved-bandwidth* [priority]
         |  |  +--ro priority     uint8
         |  |  +--ro bandwidth
         |  |     +--ro te-bandwidth
         |  |        +--ro (technology)?
         |  |           +--:(psc)
         |  |           |  +--ro psc?       rt-types:bandwidth-ieee-
   float32
         |  |           +--:(otn)
         |  |           |  +--ro otn* [rate-type]
         |  |           |     +--ro rate-type    identityref
         |  |           |     +--ro counter?     uint16
         |  |           +--:(lsc)
         |  |           |  +--ro wdm* [spectrum slot]
         |  |           |     +--ro spectrum    identityref
         |  |           |     +--ro slot        int16
         |  |           |     +--ro width?      uint16
         |  |           +--:(generic)
         |  |              +--ro generic?   te-bandwidth
         |  +--ro te-default-metric?                uint32
         |  +--ro te-delay-metric?                  uint32
         |  +--ro te-igp-metric?                    uint32
         |  +--ro te-srlgs
         |  |  +--ro value*   te-types:srlg
         |  +--ro te-nsrlgs {nsrlg}?
         |     +--ro id*   uint32
         +--ro recovery
         |  +--ro restoration-status?   te-types:te-recovery-status
         |  +--ro protection-status?    te-types:te-recovery-status
         +--ro underlay {te-topology-hierarchy}?
         |  +--ro dynamic?     boolean
         |  +--ro committed?   boolean
         +--ro statistics
            +--ro discontinuity-time                 yang:date-and-time
            +--ro disables?                          yang:counter32
            +--ro enables?                           yang:counter32
            +--ro maintenance-clears?                yang:counter32
            +--ro maintenance-sets?                  yang:counter32
            +--ro modifies?                          yang:counter32
            +--ro downs?                             yang:counter32
            +--ro ups?                               yang:counter32
            +--ro fault-clears?                      yang:counter32


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            +--ro fault-detects?                     yang:counter32
            +--ro protection-switches?               yang:counter32
            +--ro protection-reverts?                yang:counter32
            +--ro restoration-failures?              yang:counter32
            +--ro restoration-starts?                yang:counter32
            +--ro restoration-successes?             yang:counter32
            +--ro restoration-reversion-failures?    yang:counter32
            +--ro restoration-reversion-starts?      yang:counter32
            +--ro restoration-reversion-successes?   yang:counter32
   augment /nw:networks/nw:network/nw:node/nt:termination-point:
      +--rw te-tp-id?   te-types:te-tp-id
      +--rw te!
         +--rw admin-status?                     te-types:te-admin-
   status
         +--rw name?                             string
         +--rw interface-switching-capability* [switching-capability
   encoding]
         |  +--rw switching-capability    identityref
         |  +--rw encoding                identityref
         |  +--rw max-lsp-bandwidth* [priority]
         |     +--rw priority     uint8
         |     +--rw bandwidth
         |        +--rw te-bandwidth
         |           +--rw (technology)?
         |              +--:(psc)
         |              |  +--rw psc?       rt-types:bandwidth-ieee-
   float32
         |              +--:(otn)
         |              |  +--rw otn* [rate-type]
         |              |     +--rw rate-type    identityref
         |              |     +--rw counter?     uint16
         |              +--:(lsc)
         |              |  +--rw wdm* [spectrum slot]
         |              |     +--rw spectrum    identityref
         |              |     +--rw slot        int16
         |              |     +--rw width?      uint16
         |              +--:(generic)
         |                 +--rw generic?   te-bandwidth
         +--rw inter-layer-lock-id*              uint32
         +--ro oper-status?                      te-types:te-oper-status
         +--ro geolocation
            +--ro altitude?    int64
            +--ro latitude?    geographic-coordinate-degree
            +--ro longitude?   geographic-coordinate-degree





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7. TE Topology Yang Module

   <CODE BEGINS> file "ietf-te-topology@2017-07-12.yang"
   module ietf-te-topology {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology";

     prefix "tet";

     import ietf-yang-types {
       prefix "yang";
     }

     import ietf-inet-types {
       prefix "inet";
     }

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

     import ietf-network {
       prefix "nw";
     }

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

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

     organization
       "IETF Traffic Engineering Architecture and Signaling (TEAS)
        Working Group";

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




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        WG Chair: Lou Berger
                  <mailto:lberger@labn.net>

        WG Chair: Vishnu Pavan Beeram
                  <mailto:vbeeram@juniper.net>

        Editor:   Xufeng Liu
                  <mailto:Xufeng_Liu@jabil.com>

        Editor:   Igor Bryskin
                  <mailto:Igor.Bryskin@huawei.com>

        Editor:   Vishnu Pavan Beeram
                  <mailto:vbeeram@juniper.net>

        Editor:   Tarek Saad
                  <mailto:tsaad@cisco.com>

        Editor:   Himanshu Shah
                  <mailto:hshah@ciena.com>

        Editor:   Oscar Gonzalez De Dios
                  <mailto:oscar.gonzalezdedios@telefonica.com>";

     description "TE topology model";

     revision "2017-07-12" {
       description "Initial revision";
       reference "RFC XXXX: YANG Data Model for TE Topologies";
     // RFC Ed.: replace XXXX with actual RFC number and remove
     // this note
     }

     /*
      * Features
      */
     feature nsrlg {
       description
         "This feature indicates that the system supports NSRLG
          (Not Sharing Risk Link Group).";
     }


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     feature te-topology-hierarchy {
       description
         "This feature indicates that the system allows underlay
          and/or overlay TE topology hierarchy.";
     }

     feature template {
       description
         "This feature indicates that the system supports
          template configuration.";
     }

     /*
      * Typedefs
      */
     typedef geographic-coordinate-degree {
         type decimal64 {
           fraction-digits 8;
         }
         description
           "Decimal degree (DD) used to express latitude and longitude
            geographic coordinates.";
     } // geographic-coordinate-degree

     typedef te-info-source {
       type enumeration {
         enum "unknown" {
           description "The source is unknown.";
         }
         enum "locally-configured" {
           description "Configured entity.";
         }
         enum "ospfv2" {
           description "OSPFv2.";
         }
         enum "ospfv3" {
           description "OSPFv3.";
         }
         enum "isis" {
           description "ISIS.";


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         }
         enum "bgp-ls" {
           description "BGP-LS.";
           reference
             "RFC7752: North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP";
         }
         enum "system-processed" {
           description "System processed entity.";
         }
         enum "other" {
           description "Other source.";
         }
       }
       description
         "Describining the type of source that has provided the
          related information, and the source credibility.";
     } // te-info-source

     /*
      * Groupings
      */
     grouping connectivity-label-restriction-list {
       description
         "List of abel restrictions specifying what labels may or may
          not be used on a link connectivity.";
       list label-restriction {
         key "inclusive-exclusive label-start";
         description
           "List of abel restrictions specifying what labels may or may
            not be used on a link connectivity.";
         reference
           "RFC7579: General Network Element Constraint Encoding
            for GMPLS-Controlled Networks";
         leaf inclusive-exclusive {
           type enumeration {
             enum inclusive {
               description "The label or label range is inclusive.";
             }
             enum exclusive {
               description "The label or label range is exclusive.";


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             }
           }
           description
             "Whether the list item is inclusive or exclusive.";
         }
         leaf label-start {
           type rt-types:generalized-label;
           description
             "This is the starting lable if a lable range is specified.
              This is the lable value if a single lable is specified,
              in which case, attribute 'label-end' is not set.";
         }
         leaf label-end {
           type rt-types:generalized-label;
           description
             "The ending lable if a lable range is specified;
              This attribute is not set, If a single lable is
              specified.";
         }
         leaf range-bitmap {
           type binary;
           description
             "When there are gaps between label-start and label-end,
              this attribute is used to specified the possitions
              of the used labels.";
         }
       }
     } // connectivity-label-restriction-list

     grouping connectivity-matrix-entry-path-attributes {
       description
         "Attributes of connectivity matrix entry.";
       leaf is-allowed {
         type boolean;
         description
           "true  - switching is allowed,
            false - switching is disallowed.";
       }
       container underlay {
         if-feature te-topology-hierarchy;
         description "Attributes of the te-link underlay.";


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         reference
           "RFC4206: Label Switched Paths (LSP) Hierarchy with
            Generalized Multi-Protocol Label Switching (GMPLS)
            Traffic Engineering (TE)";

         uses te-link-underlay-attributes;
       } // underlay

       uses te-types:generic-path-constraints;
       uses te-types:generic-path-optimization;
       uses te-types:generic-computed-path-properties;
     } // connectivity-matrix-entry-path-attributes

     grouping geolocation-container {
       description
         "A container containing a GPS location.";
       container geolocation{
         config false;
         description
           "A container containing a GPS location.";
         leaf altitude {
           type int64;
           units millimeter;
           description
             "Distance above the sea level.";
         }
         leaf latitude {
           type geographic-coordinate-degree {
             range "-90..90";
           }
           description
             "Relative position north or south on the Earth's surface.";
         }
         leaf longitude {
           type geographic-coordinate-degree {
             range "-180..180";
           }
           description
             "Angular distance east or west on the Earth's surface.";
         }
       } // gps-location


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     } // geolocation-container

     grouping information-source-state-attributes {
       description
         "The attributes identifying source that has provided the
          related information, and the source credibility.";
       leaf credibility-preference {
         type uint16;
         description
           "The preference value to calculate the traffic
            engineering database credibility value used for
            tie-break selection between different
            information-source values.
            Higher value is more preferable.";
       }
       leaf logical-network-element {
         type string;
         description
           "When applicable, this is the name of a logical network
            element from which the information is learned.";
       } // logical-network-element
       leaf network-instance {
         type string;
         description
           "When applicable, this is the name of a network-instance
            from which the information is learned.";
       } // network-instance
     } // information-source-state-attributes

     grouping information-source-per-link-attributes {
       description
         "Per node container of the attributes identifying source that
          has provided the related information, and the source
          credibility.";
       leaf information-source {
         type te-info-source;
         config false;
         description
           "Indicates the source of the information.";
       }
       container information-source-state {


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         config false;
         description
           "The container contains state attributes related to
            the information source.";
         uses information-source-state-attributes;
         container topology {
           description
             "When the information is processed by the system,
              the attributes in this container indicate which topology
              is used to process to generate the result information.";
           uses nt:link-ref;
         } // topology
       } // information-source-state
     } // information-source-per-link-attributes

     grouping information-source-per-node-attributes {
       description
         "Per node container of the attributes identifying source that
          has provided the related information, and the source
          credibility.";
       leaf information-source {
         type te-info-source;
         config false;
         description
           "Indicates the source of the information.";
       }
       container information-source-state {
         config false;
         description
           "The container contains state attributes related to
            the information source.";
         uses information-source-state-attributes;
         container topology {
           description
             "When the information is processed by the system,
              the attributes in this container indicate which topology
              is used to process to generate the result information.";
           uses nw:node-ref;
         } // topology
       } // information-source-state
     } // information-source-per-node-attributes


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     grouping interface-switching-capability-list {
       description
         "List of Interface Switching Capabilities Descriptors (ISCD)";
       list interface-switching-capability {
         key "switching-capability encoding";
         description
           "List of Interface Switching Capabilities Descriptors (ISCD)
            for this link.";
         reference
           "RFC3471: Generalized Multi-Protocol Label Switching (GMPLS)
            Signaling Functional Description.
            RFC4203: OSPF Extensions in Support of Generalized
            Multi-Protocol Label Switching (GMPLS).";
         leaf switching-capability {
           type identityref {
             base te-types:switching-capabilities;
           }
           description
             "Switching Capability for this interface.";
         }
         leaf encoding {
           type identityref {
             base te-types:lsp-encoding-types;
           }
           description
             "Encoding supported by this interface.";
         }
         uses te-link-iscd-attributes;
       } // interface-switching-capability
     } // interface-switching-capability-list

     grouping statistics-per-link {
       description
         "Statistics attributes per TE link.";
       leaf discontinuity-time {
         type yang:date-and-time;
         mandatory true;
         description
           "The time on the most recent occasion at which any one or
            more of this interface's counters suffered a


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            discontinuity.  If no such discontinuities have occurred
            since the last re-initialization of the local management
            subsystem, then this node contains the time the local
            management subsystem re-initialized itself.";
       }
       /* Administrative attributes */
       leaf disables {
         type yang:counter32;
         description
           "Number of times that link was disabled.";
       }
       leaf enables {
         type yang:counter32;
         description
           "Number of times that link was enabled.";
       }
       leaf maintenance-clears {
         type yang:counter32;
         description
           "Number of times that link was put out of maintenance.";
       }
       leaf maintenance-sets {
         type yang:counter32;
         description
           "Number of times that link was put in maintenance.";
         }
       leaf modifies {
         type yang:counter32;
         description
           "Number of times that link was modified.";
       }
       /* Operational attributes */
       leaf downs {
         type yang:counter32;
         description
           "Number of times that link was set to operational down.";
       }
       leaf ups {
         type yang:counter32;
         description
           "Number of times that link was set to operational up.";


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       }
       /* Recovery attributes */
       leaf fault-clears {
         type yang:counter32;
         description
           "Number of times that link experienced fault clear event.";
       }
       leaf fault-detects {
         type yang:counter32;
         description
           "Number of times that link experienced fault detection.";
       }
       leaf protection-switches {
         type yang:counter32;
         description
           "Number of times that link experienced protection
            switchover.";
       }
       leaf protection-reverts {
         type yang:counter32;
         description
           "Number of times that link experienced protection
            reversion.";
       }
       leaf restoration-failures {
         type yang:counter32;
         description
           "Number of times that link experienced restoration
            failure.";
       }
       leaf restoration-starts {
         type yang:counter32;
         description
           "Number of times that link experienced restoration
            start.";
       }
       leaf restoration-successes {
         type yang:counter32;
         description
           "Number of times that link experienced restoration
            success.";


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       }
       leaf restoration-reversion-failures {
         type yang:counter32;
         description
           "Number of times that link experienced restoration reversion
            failure.";
       }
       leaf restoration-reversion-starts {
         type yang:counter32;
         description
           "Number of times that link experienced restoration reversion
            start.";
       }
       leaf restoration-reversion-successes {
         type yang:counter32;
         description
           "Number of times that link experienced restoration reversion
            success.";
       }
     } // statistics-per-link

     grouping statistics-per-node {
       description
         "Statistics attributes per TE node.";
       leaf discontinuity-time {
         type yang:date-and-time;
         mandatory true;
         description
           "The time on the most recent occasion at which any one or
            more of this interface's counters suffered a
            discontinuity.  If no such discontinuities have occurred
            since the last re-initialization of the local management
            subsystem, then this node contains the time the local
            management subsystem re-initialized itself.";
       }
       container node {
         description
           "Containing TE node level statistics attributes.";
         leaf disables {
           type yang:counter32;
           description


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             "Number of times that node was disabled.";
         }
         leaf enables {
           type yang:counter32;
           description
             "Number of times that node was enabled.";
         }
         leaf maintenance-sets {
           type yang:counter32;
           description
             "Number of times that node was put in maintenance.";
         }
         leaf maintenance-clears {
           type yang:counter32;
           description
             "Number of times that node was put out of maintenance.";
         }
         leaf modifies {
           type yang:counter32;
           description
             "Number of times that node was modified.";
         }
       } // node
       container connectivity-matrix-entry {
         description
           "Containing connectivity matrix entry level statistics
            attributes.";
         leaf creates {
           type yang:counter32;
           description
             "Number of times that a connectivity matrix entry was
              created.";
           reference
             "RFC6241. Section 7.2 for 'create' operation. ";
         }
         leaf deletes {
           type yang:counter32;
           description
             "Number of times that a connectivity matrix entry was
              deleted.";
           reference


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             "RFC6241. Section 7.2 for 'delete' operation. ";
         }
         leaf disables {
           type yang:counter32;
           description
             "Number of times that a connectivity matrix entry was
              disabled.";
         }
         leaf enables {
           type yang:counter32;
           description
             "Number of times that a connectivity matrix entry was
              enabled.";
         }
         leaf modifies {
           type yang:counter32;
           description
             "Number of times that a connectivity matrix entry was
              modified.";
         }
       } // connectivity-matrix-entry
     } // statistics-per-node

     grouping statistics-per-ttp {
       description
         "Statistics attributes per TE TTP (Tunnel Termination Point).";
       leaf discontinuity-time {
         type yang:date-and-time;
         mandatory true;
         description
           "The time on the most recent occasion at which any one or
            more of this interface's counters suffered a
            discontinuity.  If no such discontinuities have occurred
            since the last re-initialization of the local management
            subsystem, then this node contains the time the local
            management subsystem re-initialized itself.";
       }
       container tunnel-termination-point {
         description
           "Containing TE TTP (Tunnel Termination Point) level
            statistics attributes.";


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         /* Administrative attributes */
         leaf disables {
           type yang:counter32;
           description
             "Number of times that TTP was disabled.";
         }
         leaf enables {
           type yang:counter32;
           description
             "Number of times that TTP was enabled.";
         }
         leaf maintenance-clears {
           type yang:counter32;
           description
             "Number of times that TTP was put out of maintenance.";
         }
         leaf maintenance-sets {
           type yang:counter32;
           description
             "Number of times that TTP was put in maintenance.";
         }
         leaf modifies {
           type yang:counter32;
           description
             "Number of times that TTP was modified.";
         }
         /* Operational attributes */
         leaf downs {
           type yang:counter32;
           description
             "Number of times that TTP was set to operational down.";
         }
         leaf ups {
           type yang:counter32;
           description
             "Number of times that TTP was set to operational up.";
         }
         leaf in-service-clears {
           type yang:counter32;
           description
             "Number of times that TTP was taken out of service


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              (TE tunnel was released).";
         }
         leaf in-service-sets {
           type yang:counter32;
           description
             "Number of times that TTP was put in service by a TE
              tunnel (TE tunnel was set up).";
         }
       } // tunnel-termination-point

       container local-link-connectivity {
         description
           "Containing TE LLCL (Local Link Connectivity List) level
            statistics attributes.";
         leaf creates {
           type yang:counter32;
           description
             "Number of times that an LLCL entry was created.";
           reference
             "RFC6241. Section 7.2 for 'create' operation. ";
         }
         leaf deletes {
           type yang:counter32;
           description
             "Number of times that an LLCL entry was deleted.";
           reference
             "RFC6241. Section 7.2 for 'delete' operation.";
         }
         leaf disables {
           type yang:counter32;
           description
             "Number of times that an LLCL  entry was disabled.";
         }
         leaf enables {
           type yang:counter32;
           description
             "Number of times that an LLCL  entry was enabled.";
         }
         leaf modifies {
           type yang:counter32;
           description


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             "Number of times that an LLCL  entry was modified.";
         }
       } // local-link-connectivity
     } // statistics-per-ttp

     grouping te-link-augment {
       description
         "Augmentation for TE link.";
       uses te-link-config;
       uses te-link-state-derived;
       container statistics {
         config false;
         description
           "Statistics data.";
         uses statistics-per-link;
       } // statistics
     } // te-link-augment

     grouping te-link-config {
       description
         "TE link configuration grouping.";
       choice bundle-stack-level {
         description
           "The TE link can be partitioned into bundled
            links, or component links.";
         case bundle {
           container bundled-links {
             description
               "A set of bundled links.";
             reference
               "RFC4201: Link Bundling in MPLS Traffic Engineering
               (TE).";
             list bundled-link {
               key "sequence";
               description
                 "Specify a bundled interface that is
                  further partitioned.";
               leaf sequence {
                 type uint32;
                 description
                   "Identify the sequence in the bundle.";


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               }
             } // list bundled-link
           }
         }
         case component {
           container component-links {
             description
               "A set of component links";
             list component-link {
               key "sequence";
               description
                 "Specify a component interface that is
                  sufficient to unambiguously identify the
                  appropriate resources";

               leaf sequence {
                 type uint32;
                 description
                   "Identify the sequence in the bundle.";
               }
               leaf src-interface-ref {
                 type string;
                 description
                   "Reference to component link interface on the
                    source node.";
               }
               leaf des-interface-ref {
                 type string;
                 description
                   "Reference to component link interface on the
                    destinatioin node.";
               }
             }
           }
         }
       } // bundle-stack-level

       leaf-list te-link-template {
         if-feature template;
         type leafref {
           path "../../../../te/templates/link-template/name";


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         }
         description
           "The reference to a TE link template.";
       }
       uses te-link-config-attributes;
     } // te-link-config

     grouping te-link-config-attributes {
       description
         "Link configuration attributes in a TE topology.";
       container te-link-attributes {
         description "Link attributes in a TE topology.";
         leaf access-type {
           type te-types:te-link-access-type;
           description
             "Link access type, which can be point-to-point or
              multi-access.";
         }
         container external-domain {
           description
             "For an inter-domain link, specify the attributes of
              the remote end of link, to facilitate the signalling at
              local end.";
           uses nw:network-ref;
           leaf remote-te-node-id {
             type te-types:te-node-id;
             description
               "Remote TE node identifier, used together with
                remote-te-link-id to identify the remote link
                termination point in a different domain.";
           }
           leaf remote-te-link-tp-id {
             type te-types:te-tp-id;
             description
               "Remote TE link termination point identifier, used
                together with remote-te-node-id to identify the remote
                link termination point in a different domain.";
           }
           leaf plug-id {
             type uint32;
             description


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               "A topology-wide unique number that identifies on the
                network a connectivity supporting a given inter-domain
                TE link. This is more flexible alternative to specifying
                remote-te-node-id and remote-te-link-tp-id, when the
                provider does not know remote-te-node-id and
                remote-te-link-tp-id or need to give client the
                flexibility to mix-n-match multiple topologies.";
           }
         }
         leaf is-abstract {
           type empty;
           description "Present if the link is abstract.";
         }
         leaf name {
           type string;
           description "Link Name.";
         }
         container underlay {
           if-feature te-topology-hierarchy;
           description "Attributes of the te-link underlay.";
           reference
             "RFC4206: Label Switched Paths (LSP) Hierarchy with
              Generalized Multi-Protocol Label Switching (GMPLS)
              Traffic Engineering (TE)";

           uses te-link-underlay-attributes;
         } // underlay
         leaf admin-status {
           type te-types:te-admin-status;
           description
             "The administrative state of the link.";
         }

         uses te-link-info-attributes;
       } // te-link-attributes
     } // te-link-config-attributes

     grouping te-link-info-attributes {
       description
         "Advertised TE information attributes.";
       leaf link-index {


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         type uint64;
         description
           "The link identifier.  If OSPF is used, this represents an
            ospfLsdbID.  If IS-IS is used, this represents an isisLSPID.
            If a locally configured link is used, this object represents
            a unique value, which is locally defined in a router.";
       }
       leaf administrative-group {
         type te-types:admin-groups;
         description
           "Administrative group or color of the link.
            This attribute covers both administrative group (defined in
            RFC3630, RFC5329, and RFC5305), and extended administrative
            group (defined in RFC7308).";
       }

       uses interface-switching-capability-list;
       uses connectivity-label-restriction-list;

       leaf link-protection-type {
         type enumeration {
           enum "unprotected" {
             description "Unprotected.";
           }
           enum "extra-traffic" {
             description "Extra traffic.";
           }
           enum "shared" {
             description "Shared.";
           }
           enum "1-for-1" {
             description "One for one protection.";
           }
           enum "1-plus-1" {
             description "One plus one protection.";
           }
           enum "enhanced" {
             description "Enhanced protection.";
           }
         }
         description


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           "Link Protection Type desired for this link.";
         reference
           "RFC4202: Routing Extensions in Support of
            Generalized Multi-Protocol Label Switching (GMPLS).";
       }

       container max-link-bandwidth {
         uses te-types:te-bandwidth;
         description
           "Maximum bandwidth that can be seen on this link in this
            direction. Units in bytes per second.";
         reference
           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC5305: IS-IS Extensions for Traffic Engineering.";
       }
       container max-resv-link-bandwidth {
         uses te-types:te-bandwidth;
         description
           "Maximum amount of bandwidth that can be reserved in this
            direction in this link. Units in bytes per second.";
         reference
           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC5305: IS-IS Extensions for Traffic Engineering.";
       }
       list unreserved-bandwidth {
         key "priority";
         max-elements "8";
         description
           "Unreserved bandwidth for 0-7 priority levels. Units in
            bytes per second.";
         reference
           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC5305: IS-IS Extensions for Traffic Engineering.";
         leaf priority {
           type uint8 {
             range "0..7";
           }
           description "Priority.";


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         }
         container bandwidth {
           uses te-types:te-bandwidth;
           description
             "Unreserved bandwidth for this level.";
         }
       }
       leaf te-default-metric {
         type uint32;
         description
           "Traffic engineering metric.";
         reference
           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC5305: IS-IS Extensions for Traffic Engineering.";
       }
       leaf te-delay-metric {
         type uint32;
         description
           "Traffic engineering delay metric.";
         reference
           "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
       }
       leaf te-igp-metric {
         type uint32;
         description
           "IGP metric used for traffic engineering.";
         reference
           "RFC3785: Use of Interior Gateway Protocol (IGP) Metric as a
            Second MPLS Traffic Engineering (TE) Metric.";
       }
       container te-srlgs {
         description
           "Containing a list of SLRGs.";
         leaf-list value {
           type te-types:srlg;
           description "SRLG value.";
           reference
             "RFC4202: Routing Extensions in Support of
              Generalized Multi-Protocol Label Switching (GMPLS).";
         }


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       }
       container te-nsrlgs {
         if-feature nsrlg;
         description
           "Containing a list of NSRLGs (Not Sharing Risk Link
            Groups).
            When an abstract TE link is configured, this list specifies
            the request that underlay TE paths need to be mutually
            disjoint with other TE links in the same groups.";
         leaf-list id {
           type uint32;
           description
             "NSRLG ID, uniquely configured within a topology.";
           reference
             "RFC4872: RSVP-TE Extensions in Support of End-to-End
              Generalized Multi-Protocol Label Switching (GMPLS)
              Recovery";
         }
       }
     } // te-link-info-attributes

     grouping te-link-iscd-attributes {
       description
         "TE link ISCD (Interface Switching Capability Descriptor)
          attributes.";
       reference
         "Sec 1.4, RFC4203: OSPF Extensions in Support of Generalized
          Multi-Protocol Label Switching (GMPLS). Section 1.4.";
       list max-lsp-bandwidth {
         key "priority";
         max-elements "8";
         description
           "Maximum LSP Bandwidth at priorities 0-7.";
         leaf priority {
           type uint8 {
             range "0..7";
           }
           description "Priority.";
         }
         container bandwidth {
           uses te-types:te-bandwidth;


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           description
             "Max LSP Bandwidth for this level";
         }
       }
     } // te-link-iscd-attributes

     grouping te-link-state-derived {
       description
         "Link state attributes in a TE topology.";
       leaf oper-status {
         type te-types:te-oper-status;
         config false;
         description
           "The current operational state of the link.";
       }
       leaf is-transitional {
         type empty;
         config false;
         description
           "Present if the link is transitional, used as an
            alternative approach in lieu of inter-layer-lock-id
            for path computation in a TE topology covering multiple
            layers or multiple regions.";
         reference
           "RFC5212: Requirements for GMPLS-Based Multi-Region and
            Multi-Layer Networks (MRN/MLN).
            RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
            for Multi-Layer and Multi-Region Networks (MLN/MRN).";
       }
       uses information-source-per-link-attributes;
       list information-source-entry {
         key "information-source";
         config false;
         description
           "A list of information sources learned, including the one
            used.";
         uses information-source-per-link-attributes;
         uses te-link-info-attributes;
       }
       container recovery {
         config false;


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         description
           "Status of the recovery process.";
         leaf restoration-status {
           type te-types:te-recovery-status;
           description
             "Restoration status.";
         }
         leaf protection-status {
           type te-types:te-recovery-status;
           description
             "Protection status.";
         }
       }
       container underlay {
         if-feature te-topology-hierarchy;
         config false;
         description "State attributes for te-link underlay.";
         leaf dynamic {
           type boolean;
           description
             "true if the underlay is dynamically created.";
         }
         leaf committed {
           type boolean;
           description
             "true if the underlay is committed.";
         }
       }
     } // te-link-state-derived

     grouping te-link-underlay-attributes {
       description "Attributes for  te-link underlay.";
       reference
         "RFC4206: Label Switched Paths (LSP) Hierarchy with
          Generalized Multi-Protocol Label Switching (GMPLS)
          Traffic Engineering (TE)";
       leaf enabled {
         type boolean;
         description
           "'true' if the underlay is enabled.
            'false' if the underlay is disabled.";


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       }
       container primary-path {
         description
           "The service path on the underlay topology that
            supports this link.";
         uses nw:network-ref;
         list path-element {
           key "path-element-id";
           description
             "A list of path elements describing the service path.";
           leaf path-element-id {
             type uint32;
             description "To identify the element in a path.";
           }
           uses te-path-element;
         }
       } // primary-path
       list backup-path {
         key "index";
         description
           "A list of backup service paths on the underlay topology that
            protect the underlay primary path. If the primary path is
            not protected, the list contains zero elements. If the
            primary path is protected, the list contains one or more
            elements.";
         leaf index {
           type uint32;
           description
             "A sequence number to identify a backup path.";
         }
         uses nw:network-ref;
         list path-element {
           key "path-element-id";
           description
             "A list of path elements describing the backup service
              path";
           leaf path-element-id {
             type uint32;
             description "To identify the element in a path.";
           }
           uses te-path-element;


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         }
       } // underlay-backup-path
       leaf protection-type {
         type identityref {
           base te-types:lsp-prot-type;
         }
         description
           "Underlay protection type desired for this link.";
       }
       container tunnel-termination-points {
         description
           "Underlay TTP(Tunnel Termination Points) desired for this
            link.";
         leaf source {
           type binary;
           description
             "Source tunnel termination point identifier.";
         }
         leaf destination {
           type binary;
           description
             "Destination tunnel termination point identifier.";
         }
       }
       container tunnels {
         description
           "Underlay TE tunnels supporting this TE link.";
         leaf sharing {
           type boolean;
           default true;
           description
             "'true' if the underlay tunnel can be shared with other
              TE links;
              'false' if the underlay tunnel is dedicated to this
              TE link.
              This leaf is the default option for all TE tunnels,
              and may be overridden by the per TE tunnel value.";
         }
         list tunnel {
           key "tunnel-name";
           description


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             "Zero, one or more underlay TE tunnels that support this TE
              link.";
           leaf tunnel-name {
             type string;
             description
               "A tunnel name uniquely identifies an underlay TE tunnel,
                used together with the source-node of this link.
                The detailed information of this tunnel can be retrieved
                from the ietf-te model.";
             reference "RFC3209";
           }
           leaf sharing {
             type boolean;
             description
               "'true' if the underlay tunnel can be shared with other
                TE links;
                'false' if the underlay tunnel is dedicated to this
                TE link.";
           }
         } // tunnel
       } // tunnels
     } // te-link-underlay-attributes

     grouping te-node-augment {
       description
         "Augmentation for TE node.";
       uses te-node-config;
       uses te-node-state-derived;
       container statistics {
         config false;
         description
           "Statistics data.";
         uses statistics-per-node;
       } // statistics

       list tunnel-termination-point {
         key "tunnel-tp-id";
         description
           "A termination point can terminate a tunnel.";
         leaf tunnel-tp-id {
           type binary;


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           description
             "Tunnel termination point identifier.";
         }

         uses te-node-tunnel-termination-point-config;
         leaf oper-status {
           type te-types:te-oper-status;
           config false;
           description
             "The current operational state of the tunnel
              termination point.";
         }
         uses geolocation-container;
         container statistics {
           config false;
           description
             "Statistics data.";
           uses statistics-per-ttp;
         } // statistics

         // Relations to other tunnel termination points
         list supporting-tunnel-termination-point {
           key "node-ref tunnel-tp-ref";
           description
             "Identifies the tunnel termination points, that this
              tunnel termination point is depending on.";
           leaf node-ref {
             type inet:uri;
             description
               "This leaf identifies the node in which the supporting
                tunnel termination point is present.
                This node is either the supporting node or a node in
                an underlay topology.";
           }
           leaf tunnel-tp-ref {
             type binary;
             description
               "Reference to a tunnel terminiation point, which is
                either in the supporting node or a node in an
                underlay topology.";
           }


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         } // supporting-tunnel-termination-point
       } // tunnel-termination-point
     } // te-node-augment

     grouping te-node-config {
       description "TE node configuration grouping.";
       leaf-list te-node-template {
         if-feature template;
         type leafref {
           path "../../../../te/templates/node-template/name";
         }
         description
           "The reference to a TE node template.";
       }
       uses te-node-config-attributes;
     } // te-node-config

     grouping te-node-config-attributes {
       description "Configuration node attributes in a TE topology.";
       container te-node-attributes {
         description "Containing node attributes in a TE topology.";
         leaf admin-status {
           type te-types:te-admin-status;
           description
             "The administrative state of the link.";
         }
         uses te-node-connectivity-matrices;
         uses te-node-info-attributes;
       } // te-node-attributes
     } // te-node-config-attributes

     grouping te-node-config-attributes-template {
       description
         "Configuration node attributes for template in a TE topology.";
       container te-node-attributes {
         description "Containing node attributes in a TE topology.";
         leaf admin-status {
           type te-types:te-admin-status;
           description
             "The administrative state of the link.";
         }


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         uses te-node-info-attributes;
       } // te-node-attributes
     } // te-node-config-attributes-template

     grouping te-node-connectivity-matrices {
       description "Connectivity matrix on a TE node.";
       container connectivity-matrices {
         description
           "Containing connectivity matrix on a TE node.";
         leaf number-of-entries {
           type uint16;
           description
             "The number of connectivity matrix entries.
              If this number is speficied in the configuration request,
              the number is requested number of entries, which may not
              all be listed in the list;
              if this number is reported in the state data,
              the number is the current number of operational entries.";
         }
         uses connectivity-label-restriction-list;
         uses connectivity-matrix-entry-path-attributes;
         list connectivity-matrix {
           key "id";
           description
             "Represents node's switching limitations, i.e. limitations
              in interconnecting network TE links across the node.";
           reference
             "RFC7579: General Network Element Constraint Encoding
              for GMPLS-Controlled Networks.";
           leaf id {
             type uint32;
             description "Identifies the connectivity-matrix entry.";
           }
         } // connectivity-matrix
       } // connectivity-matrices
     } // te-node-connectivity-matrices

     grouping te-node-connectivity-matrix-attributes {
       description
         "Termination point references of a connectivity matrix entry.";
       container from {


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         description
           "Reference to source link termination point.";
         leaf tp-ref {
           type leafref {
             path "../../../../../../nt:termination-point/nt:tp-id";
           }
           description
             "Relative reference to a termination point.";
         }
         uses connectivity-label-restriction-list;
       }
       container to {
         description
           "Reference to destination link termination point.";
         leaf tp-ref {
           type leafref {
             path "../../../../../../nt:termination-point/nt:tp-id";
           }
           description
             "Relative reference to a termination point.";
         }
         uses connectivity-label-restriction-list;
       }
       uses connectivity-matrix-entry-path-attributes;
     } // te-node-connectivity-matrix-attributes

     grouping te-node-info-attributes {
       description
         "Advertised TE information attributes.";
       leaf domain-id {
         type uint32;
         description
           "Identifies the domain that this node belongs.
            This attribute is used to support inter-domain links.";
         reference
           "RFC5152: A Per-Domain Path Computation Method for
            Establishing Inter-Domain Traffic Engineering (TE)
            Label Switched Paths (LSPs).
            RFC5392: OSPF Extensions in Support of Inter-Autonomous
            System (AS) MPLS and GMPLS Traffic Engineering.
            RFC5316: ISIS Extensions in Support of Inter-Autonomous


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            System (AS) MPLS and GMPLS Traffic Engineering.";
       }
       leaf is-abstract {
         type empty;
         description
           "Present if the node is abstract, not present if the node
            is actual.";
       }
       leaf name {
         type inet:domain-name;
         description "Node name.";
       }
       leaf-list signaling-address {
         type inet:ip-address;
         description "Node signaling address.";
       }
       container underlay-topology {
         if-feature te-topology-hierarchy;
         description
           "When an abstract node encapsulates a topology,
            the attributes in this container point to said topology.";
         uses nw:network-ref;
       }
     } // te-node-info-attributes

     grouping te-node-state-derived {
       description "Node state attributes in a TE topology.";
       leaf oper-status {
         type te-types:te-oper-status;
         config false;
         description
           "The current operational state of the node.";
       }
       uses geolocation-container;
       leaf is-multi-access-dr {
         type empty;
         config false;
         description
           "The presence of this attribute indicates that this TE node
            is a pseudonode elected as a designated router.";
         reference


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           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC1195: Use of OSI IS-IS for Routing in TCP/IP and Dual
            Environments.";
       }
       uses information-source-per-node-attributes;
       list information-source-entry {
         key "information-source";
         config false;
         description
           "A list of information sources learned, including the one
            used.";
         uses information-source-per-node-attributes;
         uses te-node-connectivity-matrices;
         uses te-node-info-attributes;
       }
     } // te-node-state-derived

     grouping te-node-tunnel-termination-point-config {
       description
         "Termination capability of a tunnel termination point on a
          TE node.";
       uses te-node-tunnel-termination-point-config-attributes;
       container local-link-connectivities {
         description
           "Containing local link connectivity list for
            a tunnel termination point on a TE node.";
         leaf number-of-entries {
           type uint16;
           description
             "The number of local link connectivity list entries.
              If this number is speficied in the configuration request,
              the number is requested number of entries, which may not
              all be listed in the list;
              if this number is reported in the state data,
              the number is the current number of operational entries.";
         }
         uses connectivity-label-restriction-list;
         uses connectivity-matrix-entry-path-attributes;
       } // local-link-connectivities
     } // te-node-tunnel-termination-point-config


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     grouping te-node-tunnel-termination-point-config-attributes {
       description
         "Configuration attributes of a tunnel termination point on a
          TE node.";
       leaf admin-status {
         type te-types:te-admin-status;
         description
           "The administrative state of the tunnel termination point.";
       }
       leaf name {
         type string;
         description
           "A descriptive name for the tunnel termination point.";
       }
       leaf switching-capability {
         type identityref {
           base te-types:switching-capabilities;
         }
         description
           "Switching Capability for this interface.";
       }
       leaf encoding {
         type identityref {
           base te-types:lsp-encoding-types;
         }
         description
           "Encoding supported by this interface.";
       }
       leaf-list inter-layer-lock-id {
         type uint32;
         description
           "Inter layer lock ID, used for path computation in a TE
            topology covering multiple layers or multiple regions.";
         reference
           "RFC5212: Requirements for GMPLS-Based Multi-Region and
            Multi-Layer Networks (MRN/MLN).
            RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
            for Multi-Layer and Multi-Region Networks (MLN/MRN).";
       }
       leaf protection-type {


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         type identityref {
           base te-types:lsp-prot-type;
         }
         description
           "The protection type that this tunnel termination point
            is capable of.";
       }

       container client-layer-adaptation {
         description
           "Containing capability information to support a client layer
            adaption in multi-layer topology.";
         list switching-capability {
           key "switching-capability encoding";
           description
             "List of supported switching capabilities";
           reference
             "RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
              for Multi-Layer and Multi-Region Networks (MLN/MRN).
              RFC4202: Routing Extensions in Support of
              Generalized Multi-Protocol Label Switching (GMPLS).";
           leaf switching-capability {
             type identityref {
               base te-types:switching-capabilities;
             }
             description
               "Switching Capability for the client layer adaption.";
           }
           leaf encoding {
             type identityref {
               base te-types:lsp-encoding-types;
             }
             description
               "Encoding supported by the client layer adaption.";
           }
           container bandwidth {
             uses te-types:te-bandwidth;
             description
               "Bandwidth available for the client layer adaption.";
           }
         }


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       }
     } // te-node-tunnel-termination-point-config-attributes

     grouping te-node-tunnel-termination-point-llc-list {
       description
         "Local link connectivity list of a tunnel termination
          point on a TE node.";
       list local-link-connectivity {
         key "link-tp-ref";
         description
           "The termination capabilities between
            tunnel-termination-point and link termination-point.
            The capability information can be used to compute
            the tunnel path.
            The Interface Adjustment Capability Descriptors (IACD)
            [RFC6001] on each link-tp can be derived from this
            local-link-connectivity list.";
         reference
           "RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
            for Multi-Layer and Multi-Region Networks (MLN/MRN).";

         leaf link-tp-ref {
           type leafref {
             path "../../../../../nt:termination-point/nt:tp-id";
           }
           description
             "Link termination point.";
         }
         uses connectivity-label-restriction-list;
         uses connectivity-matrix-entry-path-attributes;
       } // local-link-connectivity
     } // te-node-tunnel-termination-point-config

     grouping te-path-element {
       description
         "A group of attributes defining an element in a TE path
          such as TE node, TE link, TE atomic resource or label.";
       uses te-types:explicit-route-hop_config;
     } // te-path-element

     grouping te-termination-point-augment {


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       description
         "Augmentation for TE termination point.";
       leaf te-tp-id {
         type te-types:te-tp-id;
         description
           "An identifier to uniquely identify a TE termination
            point.";
       }
       container te {
         must "../te-tp-id";
         presence "TE support.";
         description
           "Indicates TE support.";

         uses te-termination-point-config;
         leaf oper-status {
           type te-types:te-oper-status;
           config false;
           description
             "The current operational state of the link termination
              point.";
         }
         uses geolocation-container;
       } // te
     } // te-termination-point-augment

     grouping te-termination-point-config {
       description
         "TE termination point configuration grouping.";
       leaf admin-status {
         type te-types:te-admin-status;
         description
           "The administrative state of the link termination point.";
       }
       leaf name {
         type string;
         description
           "A descriptive name for the link termination point.";
       }
       uses interface-switching-capability-list;
       leaf-list inter-layer-lock-id {


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         type uint32;
         description
           "Inter layer lock ID, used for path computation in a TE
            topology covering multiple layers or multiple regions.";
         reference
           "RFC5212: Requirements for GMPLS-Based Multi-Region and
            Multi-Layer Networks (MRN/MLN).
            RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
            for Multi-Layer and Multi-Region Networks (MLN/MRN).";
       }
     } // te-termination-point-config

     grouping te-topologies-augment {
       description
         "Augmentation for TE topologies.";
       container te {
         presence "TE support.";
         description
           "Indicates TE support.";

         container templates {
           description
             "Configuration parameters for templates used for TE
              topology.";

           list node-template {
             if-feature template;
             key "name";
             leaf name {
               type te-types:te-template-name;
               description
                 "The name to identify a TE node template.";
             }
             description
               "The list of TE node templates used to define sharable
                and reusable TE node attributes.";
             uses template-attributes;
             uses te-node-config-attributes-template;
           } // node-template

           list link-template {


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             if-feature template;
             key "name";
             leaf name {
               type te-types:te-template-name;
               description
                 "The name to identify a TE link template.";
             }
             description
               "The list of TE link templates used to define sharable
                and reusable TE link attributes.";
             uses template-attributes;
             uses te-link-config-attributes;
           } // link-template
         } // templates
       } // te
     } // te-topologies-augment

     grouping te-topology-augment {
       description
         "Augmentation for TE topology.";
       leaf provider-id {
         type te-types:te-global-id;
         description
           "An identifier to uniquely identify a provider.";
       }
       leaf client-id {
         type te-types:te-global-id;
         description
           "An identifier to uniquely identify a client.";
       }
       leaf te-topology-id {
         type te-types:te-topology-id;
         description
           "It is presumed that a datastore will contain many
            topologies. To distinguish between topologies it is
            vital to have UNIQUE topology identifiers.";
       }

       container te {
         must "../provider-id and ../client-id and ../te-topology-id";
         presence "TE support.";


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         description
           "Indicates TE support.";

         uses te-topology-config;
         uses geolocation-container;
       } // te
     } // te-topology-augment

     grouping te-topology-config {
       description
         "TE topology configuration grouping.";
       leaf preference {
         type uint8 {
           range "1..255";
         }
         description
           "Specifies a preference for this topology. A lower number
            indicates a higher preference.";
       }
       leaf optimization-criterion {
         type identityref {
           base te-types:te-optimization-criterion;
         }
         description
           "Optimization criterion applied to this topology.";
         reference
           "RFC3272: Overview and Principles of Internet Traffic
            Engineering.";
       }
       list nsrlg {
         if-feature nsrlg;
         key "id";
         description
           "List of NSRLGs (Not Sharing Risk Link Groups).";
         reference
           "RFC4872: RSVP-TE Extensions in Support of End-to-End
            Generalized Multi-Protocol Label Switching (GMPLS)
            Recovery";
         leaf id {
           type uint32;
           description


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             "Identify the NSRLG entry.";
         }
         leaf disjointness {
           type te-types:te-path-disjointness;
           description
             "The type of resource disjointness.";
         }
       } // nsrlg
     } // te-topology-config

     grouping template-attributes {
       description
         "Common attributes for all templates.";
       leaf priority {
         type uint16;
         description
           "The preference value to resolve conflicts between different
            templates. When two or more templates specify values for
            one configuration attribute, the value from the template
            with the highest priority is used.";
       }
       leaf reference-change-policy {
         type enumeration {
           enum no-action {
             description
               "When an attribute changes in this template, the
                configuration node referring to this template does
                not take any action.";
           }
           enum not-allowed {
             description
               "When any configuration object has a reference to this
                template, changing this template is not allowed.";
           }
           enum cascade {
             description
               "When an attribute changes in this template, the
                configuration object referring to this template applies
                the new attribute value to the corresponding
                configuration.";
           }


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         }
         description
           "This attribute specifies the action taken to a configuration
            node that has a reference to this template.";
       }
     } // template-attributes

     /*
      * Data nodes
      */
     augment "/nw:networks/nw:network/nw:network-types" {
       description
         "Introduce new network type for TE topology.";
       container te-topology {
         presence "Indicates TE topology.";
         description
           "Its presence identifies the TE topology type.";
       }
     }

     augment "/nw:networks" {
       description
         "Augmentation parameters for TE topologies.";
       uses te-topologies-augment;
     }

     augment "/nw:networks/nw:network" {
       when "nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE topology.";
       uses te-topology-augment;
     }

     augment "/nw:networks/nw:network/nw:node" {
       when "../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with


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            TE topology type.";
       }
       description
         "Configuration parameters for TE at node level.";
       leaf te-node-id {
         type te-types:te-node-id;
         description
           "The identifier of a node in the TE topology.
            A node is specific to a topology to which it belongs.";
       }
       container te {
         must "../te-node-id" {
           description
             "te-node-id is mandatory.";
         }
         must "count(../nw:supporting-node)<=1" {
           description
             "For a node in a TE topology, there cannot be more
              than 1 supporting node. If multiple nodes are abstracted,
              the underlay-topology is used.";
         }
         presence "TE support.";
         description
           "Indicates TE support.";
         uses te-node-augment;
       } // te
     }

     augment "/nw:networks/nw:network/nt:link" {
       when "../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE at link level.";
       container te {
         must "count(../nt:supporting-link)<=1" {
           description
             "For a link in a TE topology, there cannot be more
              than 1 supporting link. If one or more link paths are


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              abstracted, the underlay is used.";
         }
         presence "TE support.";
         description
           "Indicates TE support.";
         uses te-link-augment;
       } // te
     }

     augment "/nw:networks/nw:network/nw:node/"
           + "nt:termination-point" {
       when "../../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE at termination point level.";
       uses te-termination-point-augment;
     }

     augment
       "/nw:networks/nw:network/nt:link/te/bundle-stack-level/"
       + "bundle/bundled-links/bundled-link" {
       when "../../../../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE link bundled link.";
       leaf src-tp-ref {
         type leafref {
           path "../../../../../nw:node[nw:node-id = "
             + "current()/../../../../nt:source/"
             + "nt:source-node]/"
             + "nt:termination-point/nt:tp-id";
           require-instance true;
         }
         description
           "Reference to another TE termination point on the


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            same souruce node.";
       }
       leaf des-tp-ref {
         type leafref {
           path "../../../../../nw:node[nw:node-id = "
             + "current()/../../../../nt:destination/"
             + "nt:dest-node]/"
             + "nt:termination-point/nt:tp-id";
           require-instance true;
         }
         description
           "Reference to another TE termination point on the
            same destination node.";
       }
     }

     augment
       "/nw:networks/nw:network/nw:node/te/"
       + "information-source-entry/connectivity-matrices/"
       + "connectivity-matrix" {
       when "../../../../../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE node connectivity-matrix.";
       uses te-node-connectivity-matrix-attributes;
     }

     augment
       "/nw:networks/nw:network/nw:node/te/te-node-attributes/"
       + "connectivity-matrices/connectivity-matrix" {
       when "../../../../../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE node connectivity-matrix.";
       uses te-node-connectivity-matrix-attributes;


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     }

     augment
       "/nw:networks/nw:network/nw:node/te/"
       + "tunnel-termination-point/local-link-connectivities" {
       when "../../../../nw:network-types/tet:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE node tunnel termination point LLCs
         (Local Link Connectivities).";
       uses te-node-tunnel-termination-point-llc-list;
     }
   }
   <CODE ENDS>

8. Security Considerations

   The transport protocol used for retrieving/manipulating the TE
   topology data MUST support authentication and SHOULD support
   encryption. The data-model by itself does not create any security
   implications.

9. IANA Considerations

   This document registers the following URIs in the IETF XML registry
   [RFC3688]. Following the format in [RFC3688], the following
   registration is requested to be made.

   URI: urn:ietf:params:xml:ns:yang:ietf-te-topology
   XML: N/A, the requested URI is an XML namespace.

   URI: urn:ietf:params:xml:ns:yang:ietf-te-topology-state
   XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   name: ietf-te-topology
   namespace: urn:ietf:params:xml:ns:yang:ietf-te-topology
   prefix: tet




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   name: ietf-te-topology-state
   namespace: urn:ietf:params:xml:ns:yang:ietf-te-topology-state
   prefix: tet-s

10. References

10.1. Normative References

   [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3688]   Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
               January 2004.

   [RFC6020]   Bjorklund, M., "YANG - A Data Modeling Language for the
               Network Configuration Protocol (NETCONF)", RFC 6020,
               October 2010.

   [RFC6991]   Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
               July 2013.

   [RFC3945]   Mannie, E., "Generalized Multi-Protocol Label Switching
               (GMPLS) Architecture", October 2004.

   [YANG-NET-TOPO]   Clemm, A., "A Data Model for Network Topologies",
               draft-ietf-i2rs-yang-network-topo (Work in Progress).

   [YANG-PUSH] Clemm, A., "Subscribing to YANG datastore push updates",
               draft-clemm-netconf-yang-push (Work in Progress).

   [RFC5277bis]     Clemm, A., "Subscribing to Event Notifications",
               draft-ietf-netconf-rfc5277bis (Work in Progress).

   [YANG-SCHEDULE]   Liu, X., "A YANG Data Model for Configuration
               Scheduling", draft-liu-netmod-yang-schedule (Work in
               Progress).

   [YANG-NMDA]       Bjorklund, M., Schoenwaelder, J., Shafer, P.,
               Watsen, K., and R. Wilton, "Network Management Datastore
               Architecture", draft-ietf-netmod-revised-datastores (Work
               in Progress).

10.2. Informative References

   [RFC2702]   Awduche, D., "Requirements for Traffic Engineering Over
               MPLS", RFC 2702, September 1999.



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11. Acknowledgments

   The authors would like to thank Lou Berger, Sue Hares, Mazen Khaddam,
   Cyril Margaria and Zafar Ali for participating in design discussions
   and providing valuable insights.












































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Appendix A. Companion YANG Model for Non-NMDA Compliant Implementations

   The YANG module ietf-te-topology defined in this document is designed
   to be used in conjunction with implementations that support the
   Network Management Datastore Architecture (NMDA) defined in [YANG-
   NMDA]. In order to allow implementations to use the model even in
   cases when NMDA is not supported, the following companion module
   ietf-te-topology-state is defined as a state model, which mirrors the
   module ietf-te-topology defined earlier in this document. However,
   all data nodes in the companion module are non-configurable, to
   represent the applied configuration or the derived operational
   states.

   The companion module, ietf-te-topology-state, is redundant and SHOULD
   NOT be supported by implementations that support NMDA.

   As the structure of the module ietf-te-topology-state mirrors that of
   the module ietf-te-topology. The YANG tree of the module ietf-te-
   topology-state is not depicted separately.

A.1. TE Topology State Yang Module

   <CODE BEGINS> file "ietf-te-topology-state@2017-07-12.yang"
   module ietf-te-topology-state {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology-state";

     prefix "tet-s";

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

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

     import ietf-network-state {
       prefix "nw-s";
     }

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


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     organization
       "IETF Traffic Engineering Architecture and Signaling (TEAS)
        Working Group";

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

        WG Chair: Lou Berger
                  <mailto:lberger@labn.net>

        WG Chair: Vishnu Pavan Beeram
                  <mailto:vbeeram@juniper.net>

        Editor:   Xufeng Liu
                  <mailto:Xufeng_Liu@jabil.com>

        Editor:   Igor Bryskin
                  <mailto:Igor.Bryskin@huawei.com>

        Editor:   Vishnu Pavan Beeram
                  <mailto:vbeeram@juniper.net>

        Editor:   Tarek Saad
                  <mailto:tsaad@cisco.com>

        Editor:   Himanshu Shah
                  <mailto:hshah@ciena.com>

        Editor:   Oscar Gonzalez De Dios
                  <mailto:oscar.gonzalezdedios@telefonica.com>";

     description "TE topology state model";

     revision "2017-07-12" {
       description "Initial revision";
       reference "RFC XXXX: YANG Data Model for TE Topologies";
     // RFC Ed.: replace XXXX with actual RFC number and remove
     // this note
     }


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     /*
      * Groupings
      */
     grouping te-node-connectivity-matrix-attributes {
       description
         "Termination point references of a connectivity matrix entry.";
       container from {
         description
           "Reference to source link termination point.";
         leaf tp-ref {
           type leafref {
             path "../../../../../../nt-s:termination-point/nt-s:tp-id";
           }
           description
             "Relative reference to a termination point.";
         }
         uses tet:connectivity-label-restriction-list;
       }
       container to {
         description
           "Reference to destination link termination point.";
         leaf tp-ref {
           type leafref {
             path "../../../../../../nt-s:termination-point/nt-s:tp-id";
           }
           description
             "Relative reference to a termination point.";
         }
         uses tet:connectivity-label-restriction-list;
       }
       uses tet:connectivity-matrix-entry-path-attributes;
     } // te-node-connectivity-matrix-attributes

     grouping te-node-tunnel-termination-point-llc-list {
       description
         "Local link connectivity list of a tunnel termination
          point on a TE node.";
       list local-link-connectivity {
         key "link-tp-ref";
         description


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           "The termination capabilities between
            tunnel-termination-point and link termination-point.
            The capability information can be used to compute
            the tunnel path.
            The Interface Adjustment Capability Descriptors (IACD)
            [RFC6001] on each link-tp can be derived from this
            local-link-connectivity list.";
         reference
           "RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
            for Multi-Layer and Multi-Region Networks (MLN/MRN).";

         leaf link-tp-ref {
           type leafref {
             path "../../../../../nt-s:termination-point/nt-s:tp-id";
           }
           description
             "Link termination point.";
         }
         uses tet:connectivity-label-restriction-list;
         uses tet:connectivity-matrix-entry-path-attributes;
       } // local-link-connectivity
     } // te-node-tunnel-termination-point-config

     /*
      * Data nodes
      */
     augment "/nw-s:networks/nw-s:network/nw-s:network-types" {
       description
         "Introduce new network type for TE topology.";
       container te-topology {
         presence "Indicates TE topology.";
         description
           "Its presence identifies the TE topology type.";
       }
     }

     augment "/nw-s:networks" {
       description
         "Augmentation parameters for TE topologies.";
       uses tet:te-topologies-augment;
     }


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     augment "/nw-s:networks/nw-s:network" {
       when "nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE topology.";
       uses tet:te-topology-augment;
     }

     augment "/nw-s:networks/nw-s:network/nw-s:node" {
       when "../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE at node level.";
       leaf te-node-id {
         type te-types:te-node-id;
         description
           "The identifier of a node in the TE topology.
            A node is specific to a topology to which it belongs.";
       }
       container te {
         must "../te-node-id" {
           description
             "te-node-id is mandatory.";
         }
         must "count(../nw-s:supporting-node)<=1" {
           description
             "For a node in a TE topology, there cannot be more
              than 1 supporting node. If multiple nodes are abstracted,
              the underlay-topology is used.";
         }
         presence "TE support.";
         description
           "Indicates TE support.";
         uses tet:te-node-augment;


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       } // te
     }

     augment "/nw-s:networks/nw-s:network/nt-s:link" {
       when "../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE at link level.";
       container te {
         must "count(../nt-s:supporting-link)<=1" {
           description
             "For a link in a TE topology, there cannot be more
              than 1 supporting link. If one or more link paths are
              abstracted, the underlay is used.";
         }
         presence "TE support.";
         description
           "Indicates TE support.";
         uses tet:te-link-augment;
       } // te
     }

     augment "/nw-s:networks/nw-s:network/nw-s:node/"
           + "nt-s:termination-point" {
       when "../../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Configuration parameters for TE at termination point level.";
       uses tet:te-termination-point-augment;
     }

     augment
       "/nw-s:networks/nw-s:network/nt-s:link/te/bundle-stack-level/"
       + "bundle/bundled-links/bundled-link" {
       when "../../../../nw-s:network-types/tet-s:te-topology" {


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         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE link bundled link.";
       leaf src-tp-ref {
         type leafref {
           path "../../../../../nw-s:node[nw-s:node-id = "
             + "current()/../../../../nt-s:source/"
             + "nt-s:source-node]/"
             + "nt-s:termination-point/nt-s:tp-id";
           require-instance true;
         }
         description
           "Reference to another TE termination point on the
            same souruce node.";
       }
       leaf des-tp-ref {
         type leafref {
           path "../../../../../nw-s:node[nw-s:node-id = "
             + "current()/../../../../nt-s:destination/"
             + "nt-s:dest-node]/"
             + "nt-s:termination-point/nt-s:tp-id";
           require-instance true;
         }
         description
           "Reference to another TE termination point on the
            same destination node.";
       }
     }

     augment
       "/nw-s:networks/nw-s:network/nw-s:node/te/"
       + "information-source-entry/connectivity-matrices/"
       + "connectivity-matrix" {
       when "../../../../../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }


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       description
         "Augment TE node connectivity-matrix.";
       uses te-node-connectivity-matrix-attributes;
     }

     augment
       "/nw-s:networks/nw-s:network/nw-s:node/te/te-node-attributes/"
       + "connectivity-matrices/connectivity-matrix" {
       when "../../../../../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE node connectivity-matrix.";
       uses te-node-connectivity-matrix-attributes;
     }

     augment
       "/nw-s:networks/nw-s:network/nw-s:node/te/"
       + "tunnel-termination-point/local-link-connectivities" {
       when "../../../../nw-s:network-types/tet-s:te-topology" {
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
         "Augment TE node tunnel termination point LLCs
         (Local Link Connectivities).";
       uses te-node-tunnel-termination-point-llc-list;
     }
   }
   <CODE ENDS>

Contributors

   Sergio Belotti
   Nokia
   Email: sergio.belotti@nokia.com

   Dieter Beller
   Nokia


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   Email: Dieter.Beller@nokia.com

   Carlo Perocchio
   Ericsson
   Email: carlo.perocchio@ericsson.com

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

Authors' Addresses

   Xufeng Liu
   Jabil
   Email: Xufeng_Liu@jabil.com

   Igor Bryskin
   Huawei Technologies
   Email: Igor.Bryskin@huawei.com

   Vishnu Pavan Beeram
   Juniper Networks
   Email: vbeeram@juniper.net

   Tarek Saad
   Cisco Systems Inc
   Email: tsaad@cisco.com

   Himanshu Shah
   Ciena
   Email: hshah@ciena.com

   Oscar Gonzalez De Dios
   Telefonica
   Email: oscar.gonzalezdedios@telefonica.com














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