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

Expires: January 6, April 19, 2016                                   July 6,                                October 19, 2015

                     YANG Data Model for TE Topologies
                       draft-ietf-teas-yang-te-topo-01
                      draft-ietf-teas-yang-te-topo-02

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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...............................................3
      1.2. Tree Structure - Legend...................................4
      1.3. Prefixes in Data Node Names...............................4 Names...............................5
   2. Characterizing TE Topologies...................................5
   3. Model Applicability............................................6
      3.1. Native TE Topologies......................................6
      3.2. Customized TE Topologies..................................8
   4. Modeling Considerations.......................................10
      4.1. Generic extensible Model.................................10 network topology building blocks.................10
      4.2. Model Structure..........................................10
       4.3. Technology agnostic TE Topology Identifiers.....................................11 model....................11
      4.3. Model Structure..........................................11
      4.4. Topology Identifiers.....................................12
      4.5. Generic TE Link Attributes...............................12
       4.5. Attributes...............................13
      4.6. Generic TE Node Attributes...............................12
       4.6. Attributes...............................13
      4.7. TED Information Sources..................................13
       4.7. Sources..................................14
      4.8. Overlay/Underlay Relationship............................14
       4.8. Scheduling Parameters....................................15
      4.9. Templates................................................15 Scheduling Parameters....................................16
      4.10. Notifications...........................................16 Templates...............................................16
      4.11. Notifications...........................................17
      4.12. Open Items..............................................17 Items..............................................18

   5. Tree Structure................................................17 Structure................................................18
   6. TE Topology Yang Module.......................................42 Module.......................................43
   7. Security Considerations.......................................78 Considerations.......................................79
   8. IANA Considerations...........................................78 Considerations...........................................79
   9. References....................................................78 References....................................................79
      9.1. Normative References.....................................78 References.....................................79
      9.2. Informative References...................................79 References...................................80
   10. Acknowledgments..............................................79 Acknowledgments..............................................80
   Appendix A - Schedule Model......................................80
      A.1 Tree Structure............................................80
      A.2 YANG Module...............................................81
   Contributors.....................................................82
   Authors' Addresses...............................................82

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.

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. 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 5 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
          ! 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.

   - 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.

3. Model Applicability

3.1. Native TE Topologies

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

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

                    Figure 1a: Example Network Topology

   Consider the network topology depicted in Figure 1a (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 1b. 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 1b: Native TE Topology as seen on Node R3

   Consider the network case of the topology depicted being split in Figure 1a (R1 .. R9 are a way that some
   nodes representing routers). participate in OSPF-TE while others participate in ISIS-TE
   (Figure 2a). An implementation MAY choose to construct a separate TE
   Topologies based on the information source. The native TE Topology Topologies
   constructed using all only nodes and links present in
    the given TED as that were learnt via a
   specific information source are depicted in Figure 1b. 2b. The data
   model proposed in this document can be used to retrieve/represent this
   these TE topology. 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.

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

                    Figure 2a: 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 2b: Native TE Topologies 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 2a). An implementation MAY choose to construct separate TE
    Topologies based on the information source. The native

3.2. Customized TE Topologies
    constructed using only nodes and links that were learnt via a
    specific information source are depicted in Figure 2b.

   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.

 3.2. Customized TE Topologies

    The model discussed 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.

                                  | +---+            /-\
                                  | |   | Router    (   ) WDM
                                  | +---+ Node       \-/  node
                                  |
                                  o----------------------------_____
   __
     +---+        /-\          /-\           /-\          +---+
     | R1|-------( A )--------( C )---------( E )---------| R3|
     +---+        \-/          \-/           \-/          +---+
                              /   \         /   \
                             /     \       /     \
                            /       \     /       \
                           /         \   /         \
                          /           \ /           \
         +---+          /-\           /-\           /-\          +---+
         | R2|---------( B )---------( D )---------( F )---------| R4|
         +---+          \-/           \-/           \-/          +---+

                 Figure 3: Example packet optical topology

   Consider the network topology depicted in Figure 3. 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 4a: Paths within the provider domain

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

         Figure 4b: Customized TE Topology provided to the Client

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

    Figure 4c: Customized TE Topology merged with the Client's Native TE
                                  Topology

   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 4a), a customized TE Topology as
   depicted in Figure 4b 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 4c.

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

   Figure 4c: 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 4b.

4. Modeling Considerations

4.1. Generic extensible network topology building blocks

   The generic 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].

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

          Figure 5: Augmenting the Generic Network Topology Model

4.2. Technology agnostic TE Topology model

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

                     +-------------------+
                     |     Generic       |
                     | TE Topology Model |
                     +-------------------+
                               |
            +-------------+-------------+-------------+
            |             |             |             |
            V             V             V             V
      +------------+                            +------------+
      | Technology |                            | Technology |
      |  Specific  |   ......................   |  Specific  |
      | TE Topology|                            | TE Topology|
      |   Model 1  |                            |   Model n  |
      +------------+                            +------------+

      Figure 5: Extending 6: Augmenting the generic Technology agnostic TE Topology model

 4.2.

4.3. Model Structure

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

   module: ietf-te-topology
   augment /nw:network/nw:network-types:
      +--rw te-topologies
       | te-topology!
   augment /nw:network:
      +--rw te!
         +--rw provider-id       te-global-id
         +--rw topology* [provider-id client-id te-topology-id]
       |  |  ..........
       |  |         te-global-id
         +--rw node* [te-node-id]
       |  |  |  ..........
       |  |  | te-topology-id    te-topology-id
         +--rw te-link* [te-link-id]
       |  |  |     .......... config
         |  ............
         +--ro state
         |  ............
         +--rw link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
       |  |  |  ..........
       | templates
            +--rw node-template* [name] {template}?
            |  |  ..........
       |  ............
            +--rw link-template* [name] {template}?
               ............

   augment /nw:network/nw:node:
      +--rw te!
         +--rw te-node-id    te-node-id
         +--rw config
         |  ............
         +--ro state
            ............

   augment /nw:network/nt:link:
      +--rw te!
         +--rw config
         |  ..........
         +--ro te-topologies-state
          +--ro topology* [provider-id client-id te-topology-id]
             |  ..........
             +--ro node* [te-node-id]
             |  |  ..........
             |  +--ro te-node-state
             |     ..........
             +--ro link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
             |  | state
            ..........

   augment /nw:network/nw:node/nt:termination-point:
      +--rw te!
         +--rw te-tp-id    te-tp-id
         +--rw config
         |  ............
         +--ro te-link-state
             |     .......... state
            ............

   notifications:
      +---n te-node-event
      |   ..........  ............
      +---n te-link-event
           ..........

 4.3.
         ............

4.4. 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:network:
      +--rw topology* [provider-id client-id te-topology-id]
       | te!
         +--rw provider-id       te-global-id
       |
         +--rw client-id         te-global-id
       |
         +--rw te-topology-id    te-topology-id

 4.4.

4.5. 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 performance-metric-throttle {te-performance-metric}?
        |  |  ..........
      |  .....................
        +--rw link-index?                       uint64
        +--rw administrative-group?             te-types:admin-groups
      |
        +--rw max-link-bandwidth?               decimal64
      |
        +--rw max-resv-link-bandwidth?          decimal64
      |
        +--rw unreserved-bandwidth* [priority]
        |  |  ..........
      |  .....................
        +--rw te-default-metric?                uint32
      |
        +--rw performance-metric {te-performance-metric}?
        |  |  ..........
      |  .....................
        +--rw link-protection-type?             enumeration
      |
        +--rw interface-switching-capabilities* interface-switching-capability* [switching-capability]
        |  |  ..........
      |  .....................
        +--rw te-srlgs
      |  |  ..........

 4.5.
           .....................

4.6. 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-matrix* [id]
        |  +--rw id            uint32
        |  +--rw from-link
      |     |  +--rw provider-id-ref?   leafref
      |     |  +--rw client-id-ref?     leafref from
        |  |  +--rw topology-id-ref? tp-ref?        leafref
        |  |  +--rw node-ref?      leafref
        |  |  +--rw link-end-ref?      leafref
      |     +--rw to-link
      |     |  +--rw provider-id-ref? network-ref?   leafref
        |     |  +--rw client-id-ref?     leafref to
        |  |  +--rw topology-id-ref? tp-ref?        leafref
        |  |  +--rw node-ref?      leafref
        |  |  +--rw link-end-ref? network-ref?   leafref
        |  +--rw is-allowed?   Boolean

 4.6.   boolean

4.7. 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.

   augment /nw:network/nw:node:
      +--rw te!
         ...........
         +--ro te-topologies-state
          +--ro topology* [provider-id client-id te-topology-id]
             |  ..........
             +--ro node* [te-node-id]
             |  ..........
             |  +--ro te-node-state
             |     +--ro information-source?         enumeration
             | state
            ........
            +--ro information-source-state
             |
               +--ro credibility-preference?   uint16
             |
               +--ro topology
               |        |  +--ro provider-id-ref?      leafref
               |        |  +--ro client-id-ref?        leafref
               |        |  +--ro topology-id-ref? te-topology-id-ref?   leafref
               |  +--ro network-id-ref?       leafref
               +--ro routing-instance?         string

   augment /nw:network/nt:link:
      +--rw te!
         ...........
         +--ro te-topologies-state
          +--ro topology* [provider-id client-id te-topology-id]
             |  ..........
             +--ro link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
             |  ..........
             |   +--ro te-link-state
             | state
            .........
            +--ro information-source?         enumeration
             |
            +--ro information-source-state
            |      |  +--ro credibility-preference?   uint16
            |      |  +--ro topology
            |  |  |  +--ro provider-id-ref?      leafref
            |  |  |  +--ro client-id-ref?        leafref
            |  |  |  +--ro topology-id-ref?   leafref
             |      |  +--ro routing-instance?         string
             |      +--ro alt-information-sources* [information-source]
             |         +--ro information-source
    enumeration
             |         +--ro information-source-state
             |         |  +--ro credibility-preference?   uint16
             |         |  +--ro topology
             |         |  |  +--ro provider-id-ref?   leafref
             |         |  |  +--ro client-id-ref? te-topology-id-ref?   leafref
            |  |  |  +--ro topology-id-ref? network-id-ref?       leafref
            |         |  +--ro routing-instance?         string
            +--ro alt-information-sources* [information-source]
            |         |  ..........

 4.7.  ............

4.8. 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:network/nw:node:
      +--rw node* [te-node-id] te!
         +--rw te-node-id    te-node-id
         +--rw config
         |  ..........  +--rw te-node-template*     leafref {template}?
         |  +--rw te-node-attributes
         |  |  ..........
      |     ....................
         |     +--rw underlay-topology {te-topology-hierarchy}?
         |  |  |        +--rw provider-id-ref?      leafref
         |  |  |        +--rw client-id-ref?        leafref
         |  |        +--rw te-topology-id-ref?   leafref
         |        +--rw topology-id-ref? network-id-ref?       leafref

   augment /nw:network/nt:link:
      +--rw link* [source-te-node-id source-te-link-id dest-te-node-id
    dest-te-link-id] te!
         +--rw config
         |  ..........  .........
         |  +--rw te-link-attributes
         |  |  .......
      |     ....................
         |     +--rw underlay! {te-topology-hierarchy}?
         |     |  |  +--rw underlay-primary-path
         |     |  |  |  +--rw provider-id-ref?      leafref
         |     |  |  |  +--rw client-id-ref?        leafref
         |     |  |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
         |     |  |  +--rw network-id-ref?       leafref
         |     |  |  +--rw path-element* [path-element-id]
         |     |  |  |     ..........
      |     ...............
         |     |  +--rw underlay-backup-path* [index]
         |     |  |  |  +--rw index                 uint32
         |     |  |  |  +--rw provider-id-ref?      leafref
         |     |  |  |  +--rw client-id-ref?        leafref
         |     |  |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
         |     |  |  +--rw network-id-ref?       leafref
         |     |  |  +--rw path-element* [path-element-id]
         |     |  |  |     ..........
      |     ...............
         |     |  +--rw underlay-protection-type?   uint16
         |     |  |  +--rw underlay-trail-src
         |     |  |     ..........  ...........
         |     |  |  +--rw underlay-trail-des network-ref?   leafref
         |     |  +--rw underlay-trail-des
         |     ..........

 4.8.     |     ...........

4.9. 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 and this functionality is tagged as a "feature"
   ("configuration-schedule"). [Editor's Note: The notion of
   "scheduling parameters" has wider applicability. The "schedules"
   module (which is imported by the TE Topology module) is discussed
   separately in Appendix A. The expectation is that this will
   eventually be discussed in a separate document.]

       +--rw schedules* [schedule-id] {configuration-schedule}?
       |  +--rw schedule-id          uint32
       |  +--rw start?               yang:date-and-time
       |  +--rw schedule-duration?   string
       |  +--rw repeat-interval?     string

 4.9.

4.10. 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}?
     |        ..........
     |
     +--rw node-template* [name] {template}?
     |  +--rw name                       te-template-name
     |  +--rw priority?                  uint16
     |  +--rw reference-change-policy?   enumeration
     |  +--rw te-node-template*          leafref
     |  +--rw te-node-attributes
     |     ..........
     +--rw link-template* [name] {template}?
        +--rw name                       te-template-name
        +--rw priority?                  uint16
        +--rw reference-change-policy?   enumeration
        +--rw te-link-template*          leafref
        +--rw te-link-attributes
           ..........

   A template can be constructed using multiple other templates. 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 node 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.]

 4.10.

4.11. Notifications

   Notifications are a key component of any topology data model.

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

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

   The authors would like to recommend the use of this mechanism for
   the TE-Topology notifications. They would also like to suggest the
   following extensions to [YANG-PUSH]

   - Specify specific entities that will trigger the push
     notifications. These entities can be specified by xpath, like the
     way a filter is specified.

   - Specify or limit the triggering event type, e.g. "add", "delete",
     "modify", or "all". The system sends the push notifications only
     when such events happen on the triggering entities.

   - Have an option to request either "incremental" or "full"
     notifications for an entity. For "incremental", the notification
     will contain only the changed attributes.

 4.11.

4.12. Open Items

   - Augmenting [YANG-NET-TOPO]: The generic network topology building
      blocks are discussed in [YANG-NET-TOPO]. This version of the
      document does not use any of those constructs. The next revision
      of this document should augment these constructs.

    - Coordinating changes to [YANG-PUSH]: The changes to [YANG-PUSH]
     discussed in Section 4.10 will need to be coordinated with the
     authors of that draft.

5. Tree Structure

   module: ietf-te-topology
   augment /nw:network/nw:network-types:
      +--rw te-topologies
       | te-topology!
   augment /nw:network:
      +--rw topology* [provider-id client-id te-topology-id]
       |  | te!
         +--rw provider-id       te-global-id
       |  |
         +--rw client-id         te-global-id
       |  |
         +--rw te-topology-id    te-topology-id
         +--rw config
         |  +--rw schedules
         |     +--rw schedules* schedule* [schedule-id] {configuration-schedule}?
       |  |
         |        +--rw schedule-id          uint32
         |  |  |        +--rw start?               yang:date-and-time
         |  |  |        +--rw schedule-duration?   string
         |  |  |        +--rw repeat-interval?     string
         +--ro state
         |  +--ro schedules
         |  +--rw topology-types
       |     +--ro schedule* [schedule-id]
         |        +--ro schedule-id          uint32
         |  +--rw te-topology!        +--ro start?               yang:date-and-time
         |        +--ro schedule-duration?   string
         |        +--ro repeat-interval?     string
         +--rw node* [te-node-id]
       |  |  | templates
            +--rw te-node-id            te-node-id
       |  | node-template* [name] {template}?
            |  +--rw te-node-template?     leafref {template}? name                       te-template-name
            |  +--rw priority?                  uint16
            |  +--rw reference-change-policy?   enumeration
            |  +--rw te-node-attributes
            |  |     +--rw schedules
            |     |  +--rw schedules* schedule* [schedule-id] {configuration-
    schedule}?
       |  |  |
            |     |     +--rw schedule-id          uint32
            |     |  |  |  |     +--rw start?               yang:date-and-time
            |     |  |  |  |     +--rw schedule-duration?   string
            |     |  |  |  |     +--rw repeat-interval?     string
            |  |  |  |     +--rw name?                  inet:domain-name
       |  |  | admin-status?          te-admin-status
            |     +--rw signaling-address*     inet:ip-address connectivity-matrix* [id]
            |     |  +--rw id            uint32
            |     |  +--rw flag*                  flag-type
       | from
            |     |  |  +--rw is-abstract?           boolean
       | tp-ref?        leafref
            |     |  |  +--rw underlay-topology {te-topology-hierarchy}?
       |  | node-ref?      leafref
            |     |  |  +--rw provider-id-ref? network-ref?   leafref
            |     |  +--rw to
            |     |  |  +--rw client-id-ref? tp-ref?        leafref
            |     |  |  |  |  +--rw topology-id-ref? node-ref?      leafref
            |     |  |  |  +--rw connectivity-matrix* [id]
       | network-ref?   leafref
            |     |  +--rw is-allowed?   boolean
            |     +--rw id domain-id?             uint32
            |  |  |  |     +--rw from-link flag*                  te-node-flag
            |     +--rw is-abstract?           empty
            |     +--rw name?                  inet:domain-name
            |     +--rw signaling-address*     inet:ip-address
            |     +--rw underlay-topology {te-topology-hierarchy}?
            |        +--rw provider-id-ref?      leafref
            |  |  |  |     |        +--rw client-id-ref?        leafref
            |  |  |  |     |        +--rw topology-id-ref? te-topology-id-ref?   leafref
            |  |  |  |     |        +--rw node-ref? network-id-ref?       leafref
       |  |  |  |     |
            +--rw link-end-ref?      leafref
       |  |  |  | link-template* [name] {template}?
               +--rw to-link
       |  |  |  |     |  +--rw provider-id-ref?   leafref
       |  |  |  |     |  +--rw client-id-ref?     leafref
       |  |  |  |     |  +--rw topology-id-ref?   leafref
       |  |  |  |     |  +--rw node-ref?          leafref
       |  |  |  |     |  +--rw link-end-ref?      leafref
       |  |  |  |     +--rw is-allowed?   boolean
       |  |  |  +--rw te-link* [te-link-id]
       |  |  |     +--rw te-link-id         te-link-id
       |  |  |     +--rw (stack-level)?
       |  |  |        +--:(bundle)
       |  |  |        |  +--rw bundled-links
       |  |  |        |     +--rw bundled-link* [sequence]
       |  |  |        |        +--rw sequence       uint32
       |  |  |        |        +--rw te-link-ref?   leafref
       |  |  |        +--:(component)
       |  |  |           +--rw component-links
       |  |  |              +--rw component-link* [sequence]
       |  |  |                 +--rw sequence              uint32
       |  |  |                 +--rw component-link-ref?   leafref
       |  |  +--rw link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
       |  |     +--rw source-te-node-id     leafref
       |  |     +--rw source-te-link-id     leafref
       |  |     +--rw dest-te-node-id       leafref
       |  | name                       te-template-name
               +--rw dest-te-link-id       leafref
       |  | priority?                  uint16
               +--rw te-link-template?     leafref {template}?
       |  | reference-change-policy?   enumeration
               +--rw te-link-attributes
       |
                  +--rw schedules
                  |  +--rw schedules* schedule* [schedule-id] {configuration-
    schedule}?
       |  |
                  |     +--rw schedule-id          uint32
                  |  |        |     +--rw start?               yang:date-and-time
                  |  |        |     +--rw schedule-duration?   string
                  |  |        |     +--rw repeat-interval?     string
       |  |
                  +--rw name?                               string
       |  | access-type?                      te-link-
   access-type
                  +--rw flag*                               flag-type
       |  |                             te-link-flag
                  +--rw is-abstract?                        boolean
       |  |                      empty
                  +--rw name?                             string
                  +--rw underlay! {te-topology-hierarchy}?
                  |  |        |  +--rw underlay-primary-path
                  |  |        |  |  +--rw provider-id-ref?      leafref
                  |  |        |  |  +--rw client-id-ref?        leafref
                  |  |        |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
                  |  |  +--rw network-id-ref?       leafref
                  |  |  +--rw path-element* [path-element-id]
                  |  |        |  |     +--rw path-element-id     uint32
                  |  |        |  |     +--rw (type)?
                  |  |        |  |        +--:(ipv4-address)
                  |  |        |  |        |  +--rw v4-address?         inet:ipv4-
   address
                  |  |        |  |        |  +--rw v4-prefix-length?   uint8
                  |  |        |  |        |  +--rw v4-loose?           boolean
                  |  |        |  |        +--:(ipv6-address)
                  |  |        |  |        |  +--rw v6-address?         inet:ipv6-
   address
                  |  |        |  |        |  +--rw v6-prefix-length?   uint8
                  |  |        |  |        |  +--rw v6-loose?           boolean
                  |  |        |  |        +--:(as-number)
                  |  |        |  |        |  +--rw as-number?          uint16
                  |  |        |  |        +--:(unnumbered-link)
                  |  |        |  |        |  +--rw router-id?          inet:ip-
   address
                  |  |        |  |        |  +--rw interface-id?       uint32
                  |  |        |  |        +--:(label)
                  |  |        |  |           +--rw value?              uint32
                  |  |        |  +--rw underlay-backup-path* [index]
                  |  |        |  |  +--rw index                 uint32
                  |  |        |  |  +--rw provider-id-ref?      leafref
                  |  |        |  |  +--rw client-id-ref?        leafref
                  |  |        |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
                  |  |  +--rw network-id-ref?       leafref
                  |  |  +--rw path-element* [path-element-id]
                  |  |        |  |     +--rw path-element-id     uint32
                  |  |        |  |     +--rw (type)?
                  |  |        |  |        +--:(ipv4-address)
                  |  |        |  |        |  +--rw v4-address?         inet:ipv4-
   address
                  |  |        |  |        |  +--rw v4-prefix-length?   uint8
                  |  |        |  |        |  +--rw v4-loose?           boolean
                  |  |        |  |        +--:(ipv6-address)
                  |  |        |  |        |  +--rw v6-address?         inet:ipv6-
   address
                  |  |        |  |        |  +--rw v6-prefix-length?   uint8
                  |  |        |  |        |  +--rw v6-loose?           boolean
                  |  |        |  |        +--:(as-number)
                  |  |        |  |        |  +--rw as-number?          uint16
                  |  |        |  |        +--:(unnumbered-link)
       |  |        +--:(unnumbered-link)
                  |  |        |  +--rw router-id?          inet:ip-
   address
                  |  |        |  |        |  +--rw interface-id?       uint32
                  |  |        |  |        +--:(label)
                  |  |        |  |           +--rw value?              uint32
                  |  |        |  +--rw underlay-protection-type?   uint16
                  |  |        |  +--rw underlay-trail-src
                  |  |        |  |  +--rw provider-id-ref?   leafref
       |  |        |  |  +--rw client-id-ref?     leafref
       |  |        |  |  +--rw topology-id-ref? tp-ref?        leafref
                  |  |        |  |  +--rw node-ref?      leafref
                  |  |        |  |  +--rw link-end-ref? network-ref?   leafref
                  |  |        |  +--rw underlay-trail-des
                  |  |        |     +--rw provider-id-ref?   leafref
       |  |        |     +--rw client-id-ref?     leafref
       |  |        |     +--rw topology-id-ref? tp-ref?        leafref
                  |  |        |     +--rw node-ref?      leafref
                  |  |        |     +--rw link-end-ref? network-ref?   leafref
       |  |
                  +--rw admin-status?                       enumeration
       |  |                     te-admin-
   status
                  +--rw performance-metric-throttle {te-performance-
   metric}?
                  |  |        |  +--rw unidirectional-delay-offset?
   uint32
                  |  |        |  +--rw measure-interval?
   uint32
                  |  |        |  +--rw advertisement-interval?
   uint32
                  |  |        |  +--rw suppression-interval?
   uint32
                  |  |        |  +--rw threshold-out
                  |  |        |  |  +--rw unidirectional-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-min-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-max-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-delay-variation?
   uint32
                  |  |        |  |  +--rw unidirectional-packet-loss?
   decimal64
                  |  |        |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-available-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
                  |  |        |  +--rw threshold-in
                  |  |        |  |  +--rw unidirectional-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-min-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-max-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-delay-variation?
   uint32
                  |  |        |  |  +--rw unidirectional-packet-loss?
   decimal64
                  |  |        |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-available-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
                  |  |        |  +--rw threshold-accelerated-advertisement
                  |  |        |     +--rw unidirectional-delay?
   uint32
                  |  |        |     +--rw unidirectional-min-delay?
   uint32
                  |  |        |     +--rw unidirectional-max-delay?
   uint32
                  |  |        |     +--rw unidirectional-delay-variation?
   uint32
                  |  |        |     +--rw unidirectional-packet-loss?
   decimal64
                  |  |        |     +--rw unidirectional-residual-bandwidth?
   decimal64
                  |  |        |     +--rw unidirectional-available-bandwidth?
   decimal64
                  |  |        |     +--rw unidirectional-utilized-bandwidth?
   decimal64
       |  |
                  +--rw link-index?                       uint64
       |  |
                  +--rw administrative-group?             te-
   types:admin-groups
       |  |
                  +--rw max-link-bandwidth?               decimal64
       |  |
                  +--rw max-resv-link-bandwidth?          decimal64
       |  |
                  +--rw unreserved-bandwidth* [priority]
                  |  |        |  +--rw priority     uint8
                  |  |        |  +--rw bandwidth?   decimal64
       |  |
                  +--rw te-default-metric?                uint32
       |  |
                  +--rw performance-metric {te-performance-metric}?
                  |  |        |  +--rw measurement
                  |  |        |  |  +--rw unidirectional-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-min-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-max-delay?
   uint32
                  |  |        |  |  +--rw unidirectional-delay-variation?
   uint32
                  |  |        |  |  +--rw unidirectional-packet-loss?
   decimal64
                  |  |        |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-available-bandwidth?
   decimal64
                  |  |        |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
                  |  |        |  +--rw normality
                  |  |        |     +--rw unidirectional-delay?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-min-delay?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-max-delay?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-delay-variation?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-packet-loss?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-residual-bandwidth?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-available-bandwidth?
   performance-metric-normality
                  |  |        |     +--rw unidirectional-utilized-bandwidth?
   performance-metric-normality
       |  |
                  +--rw link-protection-type?             enumeration
       |  |
                  +--rw interface-switching-capabilities* interface-switching-capability* [switching-
   capability]
                  |  |        |  +--rw switching-capability
   identityref
                  |  |        |  +--rw encoding?
   identityref
                  |  |        |  +--rw max-lsp-bandwidth* [priority]
                  |  |        |  |  +--rw priority     uint8
                  |  |        |  |  +--rw bandwidth?   decimal64
                  |  |        |  +--rw packet-switch-capable
                  |  |        |  |  +--rw minimum-lsp-bandwidth?   decimal64
                  |  |        |  |  +--rw interface-mtu?           uint16
                  |  |        |  +--rw time-division-multiplex-capable
                  |  |        |  +--rw minimum-lsp-bandwidth?   decimal64
                  |  |        |  +--rw indication?              enumeration
                  |  |  +--rw te-srlgs
       | interface-adjustment-capability* [upper-sc]
                  |     +--rw values*   te-types:srlg upper-sc             identityref
                  |     +--rw node-template* [name] {template}?
       | upper-encoding?      identityref
                  |     +--rw name                       te-template-name
       | max-lsp-bandwidth* [priority]
                  |        +--rw priority?                  uint16
       | priority     uint8
                  |        +--rw reference-change-policy?   enumeration
       | bandwidth?   decimal64
                  +--rw te-srlgs
                     +--rw values*   te-types:srlg
   augment /nw:network/nw:node:

      +--rw te!
         +--rw te-node-id    te-node-id
         +--rw config
         |  +--rw te-node-template*     leafref
       | {template}?
         |  +--rw te-node-attributes
         |     +--rw schedules
         |     |  +--rw schedules* schedule* [schedule-id] {configuration-schedule}?
       |  |
         |     |     +--rw schedule-id          uint32
         |     |  |  |     +--rw start?               yang:date-and-time
         |     |  |  |     +--rw schedule-duration?   string
         |     |  |  |     +--rw repeat-interval?     string
         |     +--rw admin-status?          te-admin-status
         |     +--rw connectivity-matrix* [id]
         |     |  +--rw name?                  inet:domain-name
       | id            uint32
         |     |  +--rw signaling-address*     inet:ip-address from
         |     |  |  +--rw flag*                  flag-type tp-ref?        leafref
         |     |  |  +--rw is-abstract?           boolean node-ref?      leafref
         |     |  |  +--rw underlay-topology {te-topology-hierarchy}?
       |  | network-ref?   leafref
         |     |  +--rw provider-id-ref?   leafref
       | to
         |     |  |  +--rw client-id-ref? tp-ref?        leafref
         |     |  |  |  +--rw topology-id-ref? node-ref?      leafref
         |     |  |  +--rw connectivity-matrix* [id] network-ref?   leafref
         |     |  +--rw is-allowed?   boolean
         |     +--rw id domain-id?             uint32
         |  |     +--rw flag*                  te-node-flag
         |     +--rw from-link is-abstract?           empty
         |     +--rw name?                  inet:domain-name
         |     +--rw signaling-address*     inet:ip-address
         |     +--rw underlay-topology {te-topology-hierarchy}?
         |        +--rw provider-id-ref?      leafref
         |        +--rw client-id-ref?        leafref
         |  |        +--rw te-topology-id-ref?   leafref
         |        +--rw client-id-ref? network-id-ref?       leafref
         +--ro state
            +--ro te-node-template*           leafref {template}?
            +--ro te-node-attributes
            |  +--ro schedules
            |  |  +--ro schedule* [schedule-id]
            |  |  +--rw topology-id-ref?   leafref     +--ro schedule-id          uint32
            |  |     +--ro start?               yang:date-and-time
            |  |  +--rw node-ref?          leafref     +--ro schedule-duration?   string
            |  |     +--ro repeat-interval?     string
            |  +--ro admin-status?          te-admin-status
            |  +--rw link-end-ref?      leafref  +--ro connectivity-matrix* [id]
            |  |  +--ro id            uint32
            |     +--rw to-link  |  +--ro from
            |  |  |  +--rw provider-id-ref?  +--ro tp-ref?        leafref
            |  |  |  +--ro node-ref?      leafref
            |  +--rw client-id-ref?  |  |  +--ro network-ref?   leafref
            |  |  +--ro to
            |  |  +--rw topology-id-ref?   leafref  |  +--ro tp-ref?        leafref
            |  |  |  +--rw  +--ro node-ref?      leafref
            |  |  |     |  +--rw link-end-ref?  +--ro network-ref?   leafref
            |  |  |     +--rw  +--ro is-allowed?   boolean
            |  +--ro domain-id?             uint32
            |  +--ro flag*                  te-node-flag
            |  +--rw te-link* [te-link-id]  +--ro is-abstract?           empty
            |  +--ro name?                  inet:domain-name
            |     +--rw te-link-id         te-link-id  +--ro signaling-address*     inet:ip-address
            |  +--ro underlay-topology {te-topology-hierarchy}?
            |     +--ro provider-id-ref?      leafref
            |     +--ro client-id-ref?        leafref
            |     +--ro te-topology-id-ref?   leafref
            |     +--ro network-id-ref?       leafref
            +--ro oper-status?                te-oper-status
            +--ro is-multi-access-dr?         empty
            +--ro information-source?         enumeration
            +--ro information-source-state
               +--ro credibility-preference?   uint16
               +--ro topology
               |  +--ro provider-id-ref?      leafref
               |  +--ro client-id-ref?        leafref
               |  +--ro te-topology-id-ref?   leafref
               |  +--ro network-id-ref?       leafref
               +--ro routing-instance?         string
   augment /nw:network/nt:link:
      +--rw te!
         +--rw config
         |  +--rw (stack-level)? (bundle-stack-level)?
         |  |  +--:(bundle)
         |  |  |  +--rw bundled-links
         |  |  |     +--rw bundled-link* [sequence]
         |  |  |        +--rw sequence      uint32
         |  |  |        +--rw te-link-ref? src-tp-ref?   leafref
         |  |  |        +--rw des-tp-ref?   leafref
         |  |  +--:(component)
         |  |     +--rw component-links
         |  |        +--rw component-link* [sequence]
         |  |           +--rw sequence             uint32
         |  |           +--rw component-link-ref?   leafref
       |  +--rw link-template* [name] {template}?
       |     +--rw name                       te-template-name src-interface-ref?   string
         |     +--rw priority?                  uint16  |           +--rw reference-change-policy?   enumeration des-interface-ref?   string
         |  +--rw te-link-template*     leafref {template}?
         |  +--rw te-link-attributes
         |     +--rw schedules* schedules
         |     |  +--rw schedule* [schedule-id] {configuration-schedule}?
         |     |     +--rw schedule-id          uint32
         |     |     +--rw start?               yang:date-and-time
         |     |     +--rw schedule-duration?   string
         |     |     +--rw repeat-interval?     string
         |     +--rw name?                               string access-type?                      te-link-access-
   type
         |     +--rw flag*                               flag-type                             te-link-flag
         |     +--rw is-abstract?                        boolean                      empty
         |     +--rw name?                             string
         |     +--rw underlay! {te-topology-hierarchy}?
         |     |  +--rw underlay-primary-path
         |     |  |  +--rw provider-id-ref?      leafref
         |     |  |  +--rw client-id-ref?        leafref
         |     |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
         |     |  |  +--rw network-id-ref?       leafref
         |     |  |  +--rw path-element* [path-element-id]
         |     |  |     +--rw path-element-id     uint32
         |     |  |     +--rw (type)?
         |     |  |        +--:(ipv4-address)
         |     |  |        |  +--rw v4-address?         inet:ipv4-
   address
         |     |  |        |  +--rw v4-prefix-length?   uint8
         |     |  |        |  +--rw v4-loose?           boolean
         |     |  |        +--:(ipv6-address)
         |     |  |        |  +--rw v6-address?         inet:ipv6-
   address
         |     |  |        |  +--rw v6-prefix-length?   uint8
         |     |  |        |  +--rw v6-loose?           boolean
         |     |  |        +--:(as-number)
         |     |  |        |  +--rw as-number?          uint16
         |     |  |        +--:(unnumbered-link)
         |     |  |        |  +--rw router-id?          inet:ip-address
         |     |  |        |  +--rw interface-id?       uint32
         |     |  |        +--:(label)
         |     |  |           +--rw value?              uint32
         |     |  +--rw underlay-backup-path* [index]
         |     |  |  +--rw index                 uint32
         |     |  |  +--rw provider-id-ref?      leafref
         |     |  |  +--rw client-id-ref?        leafref
         |     |  |  +--rw topology-id-ref? te-topology-id-ref?   leafref
         |     |  |  +--rw network-id-ref?       leafref
         |     |  |  +--rw path-element* [path-element-id]
         |     |  |     +--rw path-element-id     uint32
         |     |  |     +--rw (type)?
         |     |  |        +--:(ipv4-address)
         |     |  |        |  +--rw v4-address?         inet:ipv4-
   address
         |     |  |        |  +--rw v4-prefix-length?   uint8
         |     |  |        |  +--rw v4-loose?           boolean
         |     |  |        +--:(ipv6-address)
         |     |  |        |  +--rw v6-address?         inet:ipv6-
   address
         |     |  |        |  +--rw v6-prefix-length?   uint8
         |     |  |        |  +--rw v6-loose?           boolean
         |     |  |        +--:(as-number)
         |     |  |        |  +--rw as-number?          uint16
         |     |  |        +--:(unnumbered-link)
         |     |  |        |  +--rw router-id?          inet:ip-address
         |     |  |        |  +--rw interface-id?       uint32
         |     |  |        +--:(label)
         |     |  |           +--rw value?              uint32
         |     |  +--rw underlay-protection-type?   uint16
         |     |  +--rw underlay-trail-src
         |     |  |  +--rw provider-id-ref?   leafref
       |        |  |  +--rw client-id-ref?     leafref
       |        |  |  +--rw topology-id-ref? tp-ref?        leafref
         |     |  |  +--rw node-ref?      leafref
         |     |  |  +--rw link-end-ref? network-ref?   leafref
         |     |  +--rw underlay-trail-des
         |     |     +--rw provider-id-ref? tp-ref?        leafref
         |     |     +--rw client-id-ref? node-ref?      leafref
         |     |     +--rw topology-id-ref? network-ref?   leafref
         |        |     +--rw node-ref?          leafref
       |        |     +--rw link-end-ref?      leafref
       |        +--rw admin-status?                       enumeration admin-status?                     te-admin-status
         |     +--rw performance-metric-throttle {te-performance-
   metric}?
         |     |  +--rw unidirectional-delay-offset?           uint32
         |     |  +--rw measure-interval?                      uint32
         |     |  +--rw advertisement-interval?                uint32
         |     |  +--rw suppression-interval?                  uint32
         |     |  +--rw threshold-out
         |     |  |  +--rw unidirectional-delay?                 uint32
         |     |  |  +--rw unidirectional-min-delay?             uint32
         |     |  |  +--rw unidirectional-max-delay?             uint32
         |     |  |  +--rw unidirectional-delay-variation?       uint32
         |     |  |  +--rw unidirectional-packet-loss?
   decimal64
         |     |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-available-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
         |     |  +--rw threshold-in
         |     |  |  +--rw unidirectional-delay?                 uint32
         |     |  |  +--rw unidirectional-min-delay?             uint32
         |     |  |  +--rw unidirectional-max-delay?             uint32
         |     |  |  +--rw unidirectional-delay-variation?       uint32
         |     |  |  +--rw unidirectional-packet-loss?
   decimal64
         |     |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-available-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
         |     |  +--rw threshold-accelerated-advertisement
         |     |     +--rw unidirectional-delay?                 uint32
         |     |     +--rw unidirectional-min-delay?             uint32
         |     |     +--rw unidirectional-max-delay?             uint32
         |     |     +--rw unidirectional-delay-variation?       uint32
         |     |     +--rw unidirectional-packet-loss?
   decimal64
         |     |     +--rw unidirectional-residual-bandwidth?
   decimal64
         |     |     +--rw unidirectional-available-bandwidth?
   decimal64
         |     |     +--rw unidirectional-utilized-bandwidth?
   decimal64
         |     +--rw link-index?                       uint64
         |     +--rw administrative-group?               te-
    types:admin-groups             te-types:admin-
   groups
         |     +--rw max-link-bandwidth?               decimal64
         |     +--rw max-resv-link-bandwidth?          decimal64
         |     +--rw unreserved-bandwidth* [priority]
         |     |  +--rw priority     uint8
         |     |  +--rw bandwidth?   decimal64
         |     +--rw te-default-metric?                uint32
         |     +--rw performance-metric {te-performance-metric}?
         |     |  +--rw measurement
         |     |  |  +--rw unidirectional-delay?                 uint32
         |     |  |  +--rw unidirectional-min-delay?             uint32
         |     |  |  +--rw unidirectional-max-delay?             uint32
         |     |  |  +--rw unidirectional-delay-variation?       uint32
         |     |  |  +--rw unidirectional-packet-loss?
   decimal64
         |     |  |  +--rw unidirectional-residual-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-available-bandwidth?
   decimal64
         |     |  |  +--rw unidirectional-utilized-bandwidth?
   decimal64
         |     |  +--rw normality
         |     |     +--rw unidirectional-delay?
   performance-metric-normality
         |     |     +--rw unidirectional-min-delay?
   performance-metric-normality
         |     |     +--rw unidirectional-max-delay?
   performance-metric-normality
         |     |     +--rw unidirectional-delay-variation?
   performance-metric-normality
         |     |     +--rw unidirectional-packet-loss?
   performance-metric-normality
         |     |     +--rw unidirectional-residual-bandwidth?
   performance-metric-normality
         |     |     +--rw unidirectional-available-bandwidth?
   performance-metric-normality
         |     |     +--rw unidirectional-utilized-bandwidth?
   performance-metric-normality
         |     +--rw link-protection-type?             enumeration
         |     +--rw interface-switching-capabilities* interface-switching-capability* [switching-
   capability]
         |     |  +--rw switching-capability               identityref
         |     |  +--rw encoding?                          identityref
         |     |  +--rw max-lsp-bandwidth* [priority]
         |     |  |  +--rw priority     uint8
         |     |  |  +--rw bandwidth?   decimal64
         |     |  +--rw packet-switch-capable
         |     |  |  +--rw minimum-lsp-bandwidth?   decimal64
         |     |  |  +--rw interface-mtu?           uint16
         |     |  +--rw time-division-multiplex-capable
         |     |  |  +--rw minimum-lsp-bandwidth?   decimal64
         |     |  |  +--rw indication?              enumeration
         |     |  +--rw interface-adjustment-capability* [upper-sc]
         |     |     +--rw upper-sc             identityref
         |     |     +--rw upper-encoding?      identityref
         |     |     +--rw max-lsp-bandwidth* [priority]
         |     |        +--rw priority     uint8
         |     |        +--rw bandwidth?   decimal64
         |     +--rw te-srlgs
         |        +--rw values*   te-types:srlg
         +--ro te-topologies-state state
            +--ro topology* [provider-id client-id te-topology-id] (bundle-stack-level)?
            |  +--:(bundle)
            |  |  +--ro provider-id        te-global-id bundled-links
            |  |     +--ro client-id          te-global-id bundled-link* [sequence]
            |  |        +--ro te-topology-id     te-topology-id sequence      uint32
            |  |        +--ro server-provided?   boolean src-tp-ref?   leafref
            |  |        +--ro topology-types des-tp-ref?   leafref
            |  +--:(component)
            |     +--ro te-topology! component-links
            |        +--ro node* [te-node-id] component-link* [sequence]
            |           +--ro te-node-id            te-node-id sequence             uint32
            |           +--ro te-node-template? src-interface-ref?   string
            |           +--ro des-interface-ref?   string
            +--ro te-link-template*           leafref {template}?
            +--ro te-link-attributes
            |  +--ro te-node-attributes schedules
            |  |  +--ro schedules* schedule* [schedule-id] {configuration-
    schedule}?
             |
            |  |     +--ro schedule-id          uint32
            |  |  |     +--ro start?               yang:date-and-time
            |  |  |     +--ro schedule-duration?   string
            |  |  |     +--ro repeat-interval?     string
            |  |  +--ro name?                  inet:domain-name
             |  |  +--ro signaling-address*     inet:ip-address
             | access-type?                      te-link-access-
   type
            |  +--ro flag*                  flag-type
             |                             te-link-flag
            |  +--ro is-abstract?           boolean                      empty
            |  +--ro name?                             string
            |  +--ro underlay-topology underlay! {te-topology-hierarchy}?
            |  |  +--ro underlay-primary-path
            |  |  |  +--ro provider-id-ref?      leafref
            |  |  |  +--ro client-id-ref?        leafref
            |  |  |  +--ro topology-id-ref? te-topology-id-ref?   leafref
            |  |  |  +--ro connectivity-matrix* [id] network-id-ref?       leafref
            |  |  |  +--ro id            uint32 path-element* [path-element-id]
            |  |  |     +--ro from-link path-element-id     uint32
            |  |  |     +--ro provider-id-ref?   leafref (type)?
            |  |  |  +--ro client-id-ref?     leafref        +--:(ipv4-address)
            |  |  |        |  +--ro topology-id-ref?   leafref v4-address?         inet:ipv4-
   address
            |  |  |        |  +--ro node-ref?          leafref v4-prefix-length?   uint8
            |  |  |        |  +--ro link-end-ref?      leafref v4-loose?           boolean
            |  |     +--ro to-link  |        +--:(ipv6-address)
            |  |  |        |  +--ro provider-id-ref?   leafref v6-address?         inet:ipv6-
   address
            |  |  |        |  +--ro client-id-ref?     leafref v6-prefix-length?   uint8
            |  |  |        |  +--ro topology-id-ref?   leafref v6-loose?           boolean
            |  |  |  +--ro node-ref?          leafref        +--:(as-number)
            |  |  |        |  +--ro link-end-ref?      leafref as-number?          uint16
            |  |     +--ro is-allowed?   boolean  |  +--ro te-link* [te-link-id]        +--:(unnumbered-link)
            |  |  |        |  +--ro te-link-id         te-link-id router-id?          inet:ip-address
            |  |  |        |  +--ro (stack-level)? interface-id?       uint32
            |  |     +--:(bundle)  |        +--:(label)
            |  |  +--ro bundled-links  |           +--ro value?              uint32
            |  |  +--ro bundled-link* [sequence] underlay-backup-path* [index]
            |  |  |  +--ro sequence index                 uint32
            |  |  |  +--ro te-link-ref? provider-id-ref?      leafref
            |  |     +--:(component)
             |  |  +--ro component-links
             | client-id-ref?        leafref
            |           +--ro component-link* [sequence]  |  |  +--ro sequence              uint32 te-topology-id-ref?   leafref
            |  |  |  +--ro component-link-ref? network-id-ref?       leafref
            |  +--ro te-node-state  |     +--ro information-source?         enumeration  |  +--ro information-source-state path-element* [path-element-id]
            |  |        +--ro credibility-preference?   uint16  |     +--ro topology path-element-id     uint32
            |  |  |     +--ro provider-id-ref?   leafref (type)?
            |  |  |        +--:(ipv4-address)
            |  |  |        |  +--ro client-id-ref?     leafref v4-address?         inet:ipv4-
   address
            |  |  |        |  +--ro topology-id-ref?   leafref
             |        +--ro routing-instance?         string
             +--ro link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
                +--ro source-te-node-id     leafref
                +--ro source-te-link-id     leafref
                +--ro dest-te-node-id       leafref
                +--ro dest-te-link-id       leafref
                +--ro te-link-template?     leafref {template}?
                +--ro te-link-attributes
                |  +--ro schedules* [schedule-id] {configuration-
    schedule}?
                |  |  +--ro schedule-id          uint32
                |  |  +--ro start?               yang:date-and-time
                |  |  +--ro schedule-duration?   string
                |  |  +--ro repeat-interval?     string
                |  +--ro name?                               string
                |  +--ro flag*                               flag-type
                |  +--ro is-abstract?                        boolean
                |  +--ro underlay! {te-topology-hierarchy}?
                |  |  +--ro underlay-primary-path
                |  |  |  +--ro provider-id-ref?   leafref
                |  |  |  +--ro client-id-ref?     leafref
                |  |  |  +--ro topology-id-ref?   leafref
                |  |  |  +--ro path-element* [path-element-id]
                |  |  |     +--ro path-element-id     uint32
                |  |  |     +--ro (type)?
                |  |  |        +--:(ipv4-address)
                |  |  |        |  +--ro v4-address?         inet:ipv4-
    address
                |  |  |        |  +--ro v4-prefix-length?   uint8
                |  |  | v4-prefix-length?   uint8
            |  |  |        |  +--ro v4-loose?           boolean
            |  |  |        +--:(ipv6-address)
            |  |  |        |  +--ro v6-address?         inet:ipv6-
   address
            |  |  |        |  +--ro v6-prefix-length?   uint8
            |  |  |        |  +--ro v6-loose?           boolean
            |  |  |        +--:(as-number)
            |  |  |        |  +--ro as-number?          uint16
            |  |  |        +--:(unnumbered-link)
            |  |  |        |  +--ro router-id?          inet:ip-
    address          inet:ip-address
            |  |  |        |  +--ro interface-id?       uint32
            |  |  |        +--:(label)
            |  |  |           +--ro value?              uint32
            |  |  +--ro underlay-backup-path* [index]
                | underlay-protection-type?   uint16
            |  |  +--ro index              uint32 underlay-trail-src
            |  |  |  +--ro provider-id-ref? tp-ref?        leafref
            |  |  |  +--ro client-id-ref? node-ref?      leafref
            |  |  |  +--ro topology-id-ref? network-ref?   leafref
            |  |  |  +--ro path-element* [path-element-id]
                | underlay-trail-des
            |  |     +--ro path-element-id     uint32
                | tp-ref?        leafref
            |  |     +--ro (type)?
                | node-ref?      leafref
            |  |        +--:(ipv4-address)     +--ro network-ref?   leafref
            |  +--ro admin-status?                     te-admin-status
            |  +--ro performance-metric-throttle {te-performance-
   metric}?
            |  |  +--ro v4-address?         inet:ipv4-
    address unidirectional-delay-offset?           uint32
            |  |  +--ro measure-interval?                      uint32
            |  |  +--ro v4-prefix-length?   uint8 advertisement-interval?                uint32
            |  |  +--ro suppression-interval?                  uint32
            |  |  +--ro v4-loose?           boolean
                | threshold-out
            |  |        +--:(ipv6-address)  |  +--ro unidirectional-delay?                 uint32
            |  |  |  +--ro v6-address?         inet:ipv6-
    address
                | unidirectional-min-delay?             uint32
            |  |  |  +--ro v6-prefix-length?   uint8
                | unidirectional-max-delay?             uint32
            |  |  |  +--ro v6-loose?           boolean
                | unidirectional-delay-variation?       uint32
            |  |        +--:(as-number)  |  +--ro unidirectional-packet-loss?
   decimal64
            |  |  |  +--ro as-number?          uint16
                | unidirectional-residual-bandwidth?
   decimal64
            |  |        +--:(unnumbered-link)  |  +--ro unidirectional-available-bandwidth?
   decimal64
            |  |  |  +--ro router-id?          inet:ip-
    address unidirectional-utilized-bandwidth?
   decimal64
            |  |  +--ro threshold-in
            |  |  |  +--ro interface-id? unidirectional-delay?                 uint32
            |  |  |        +--:(label)  +--ro unidirectional-min-delay?             uint32
            |  |  |  +--ro value? unidirectional-max-delay?             uint32
            |  |  +--ro underlay-protection-type?   uint16
                |  |  +--ro underlay-trail-src unidirectional-delay-variation?       uint32
            |  |  |  +--ro provider-id-ref?   leafref unidirectional-packet-loss?
   decimal64
            |  |  |  +--ro client-id-ref?     leafref unidirectional-residual-bandwidth?
   decimal64
            |  |  |  +--ro topology-id-ref?   leafref unidirectional-available-bandwidth?
   decimal64
            |  |  |  +--ro node-ref?          leafref
                | unidirectional-utilized-bandwidth?
   decimal64
            |  |  +--ro link-end-ref?      leafref threshold-accelerated-advertisement
            |  |     +--ro underlay-trail-des
                |  |  |  +--ro provider-id-ref?   leafref
                |  |  |  +--ro client-id-ref?     leafref
                |  |  |  +--ro topology-id-ref?   leafref
                |  |  |  +--ro node-ref?          leafref
                |  |  |  +--ro link-end-ref?      leafref
                |  |  +--ro dynamic?                    boolean
                |  |  +--ro committed?                  boolean
                |  +--ro admin-status?                       enumeration
                |  +--ro performance-metric-throttle {te-performance-
    metric}?
                |  |  +--ro unidirectional-delay-offset?
    uint32
                |  |  +--ro measure-interval?
    uint32
                |  |  +--ro advertisement-interval?
    uint32
                |  |  +--ro suppression-interval?
    uint32
                |  |  +--ro threshold-out
                |  |  |  +--ro unidirectional-delay?
    uint32
                |  |  |  +--ro unidirectional-min-delay?
    uint32
                |  |  |  +--ro unidirectional-max-delay?
    uint32
                |  |  |  +--ro unidirectional-delay-variation?
    uint32
                |  |  |  +--ro unidirectional-packet-loss?
    decimal64
                |  |  |  +--ro unidirectional-residual-bandwidth?
    decimal64
                |  |  |  +--ro unidirectional-available-bandwidth?
    decimal64
                |  |  |  +--ro unidirectional-utilized-bandwidth?
    decimal64
                |  |  +--ro threshold-in
                |  |  |  +--ro unidirectional-delay?
    uint32
                |  |  |  +--ro unidirectional-min-delay?
    uint32
                |  |  |  +--ro unidirectional-max-delay?
    uint32
                |  |  |  +--ro unidirectional-delay-variation?
    uint32
                |  |  |  +--ro unidirectional-packet-loss?
    decimal64
                |  |  |  +--ro unidirectional-residual-bandwidth?
    decimal64
                |  |  |  +--ro unidirectional-available-bandwidth?
    decimal64
                |  |  |  +--ro unidirectional-utilized-bandwidth?
    decimal64
                |  |  +--ro threshold-accelerated-advertisement
                |  |     +--ro unidirectional-delay?
    uint32 unidirectional-delay?                 uint32
            |  |     +--ro unidirectional-min-delay?             uint32
            |  |     +--ro unidirectional-max-delay?             uint32
            |  |     +--ro unidirectional-delay-variation?       uint32
            |  |     +--ro unidirectional-packet-loss?
   decimal64
            |  |     +--ro unidirectional-residual-bandwidth?
   decimal64
            |  |     +--ro unidirectional-available-bandwidth?
   decimal64
            |  |     +--ro unidirectional-utilized-bandwidth?
   decimal64
            |  +--ro link-index?                       uint64
            |  +--ro administrative-group?               te-
    types:admin-groups             te-types:admin-
   groups
            |  +--ro max-link-bandwidth?               decimal64
            |  +--ro max-resv-link-bandwidth?          decimal64
            |  +--ro unreserved-bandwidth* [priority]
            |  |  +--ro priority     uint8
            |  |  +--ro bandwidth?   decimal64
            |  +--ro te-default-metric?                uint32
            |  +--ro performance-metric {te-performance-metric}?
            |  |  +--ro measurement
            |  |  |  +--ro unidirectional-delay?                 uint32
            |  |  |  +--ro unidirectional-min-delay?             uint32
            |  |  |  +--ro unidirectional-max-delay?             uint32
            |  |  |  +--ro unidirectional-delay-variation?       uint32
            |  |  |  +--ro unidirectional-packet-loss?
   decimal64
            |  |  |  +--ro unidirectional-residual-bandwidth?
   decimal64
            |  |  |  +--ro unidirectional-available-bandwidth?
   decimal64
            |  |  |  +--ro unidirectional-utilized-bandwidth?
   decimal64
            |  |  +--ro normality
            |  |     +--ro unidirectional-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-min-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-max-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-delay-variation?
   performance-metric-normality
            |  |     +--ro unidirectional-packet-loss?
   performance-metric-normality
            |  |     +--ro unidirectional-residual-bandwidth?
   performance-metric-normality
            |  |     +--ro unidirectional-available-bandwidth?
   performance-metric-normality
            |  |     +--ro unidirectional-utilized-bandwidth?
   performance-metric-normality
            |  +--ro link-protection-type?             enumeration
            |  +--ro interface-switching-capabilities* interface-switching-capability* [switching-
   capability]
            |  |  +--ro switching-capability               identityref
            |  |  +--ro encoding?                          identityref
            |  |  +--ro max-lsp-bandwidth* [priority]
            |  |  |  +--ro priority     uint8
            |  |  |  +--ro bandwidth?   decimal64
            |  |  +--ro packet-switch-capable
            |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
            |  |  |  +--ro interface-mtu?           uint16
            |  |  +--ro time-division-multiplex-capable
            |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
            |  |  |  +--ro indication?              enumeration
            |  |  +--ro interface-adjustment-capability* [upper-sc]
            |  |     +--ro upper-sc             identityref
            |  |     +--ro upper-encoding?      identityref
            |  |     +--ro max-lsp-bandwidth* [priority]
            |  |        +--ro priority     uint8
            |  |        +--ro bandwidth?   decimal64
            |  +--ro te-srlgs
            |     +--ro values*   te-types:srlg
            +--ro te-link-state
                   +--ro oper-status?                enumeration                te-oper-status
            +--ro information-source?         enumeration
            +--ro information-source-state
            |  +--ro credibility-preference?   uint16
            |  +--ro topology
            |  |  +--ro provider-id-ref?      leafref
            |  |  +--ro client-id-ref?        leafref
            |  |  +--ro topology-id-ref? te-topology-id-ref?   leafref
            |  |  +--ro network-id-ref?       leafref
            |  +--ro routing-instance?         string
            +--ro alt-information-sources* [information-source]
            |  +--ro information-source                enumeration
            |  +--ro information-source-state
            |  |  +--ro credibility-preference?   uint16
            |  |  +--ro topology
            |  |  |  +--ro provider-id-ref?      leafref
            |  |  |  +--ro client-id-ref?        leafref
            |  |  |  +--ro te-topology-id-ref?   leafref
            |  |  |  +--ro topology-id-ref? network-id-ref?       leafref
            |  |  +--ro routing-instance?         string
            |  +--ro link-index?                       uint64
            |  +--ro administrative-group?               te-
    types:admin-groups             te-types:admin-
   groups
            |  +--ro max-link-bandwidth?               decimal64
            |  +--ro max-resv-link-bandwidth?          decimal64
            |  +--ro unreserved-bandwidth* [priority]
            |  |  +--ro priority     uint8
            |  |  +--ro bandwidth?   decimal64
            |  +--ro te-default-metric?                uint32
            |  +--ro performance-metric {te-performance-metric}?
            |  |  +--ro measurement
            |  |  |  +--ro unidirectional-delay?                 uint32
            |  |  |  +--ro unidirectional-min-delay?             uint32
            |  |  |  +--ro unidirectional-max-delay?             uint32
            |  |  |  +--ro unidirectional-delay-variation?       uint32
            |  |  |  +--ro unidirectional-packet-loss?
   decimal64
            |  |  |  +--ro unidirectional-residual-bandwidth?
   decimal64
            |  |  |  +--ro unidirectional-available-bandwidth?
   decimal64
            |  |  |  +--ro unidirectional-utilized-bandwidth?
   decimal64
            |  |  +--ro normality
            |  |     +--ro unidirectional-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-min-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-max-delay?
   performance-metric-normality
            |  |     +--ro unidirectional-delay-variation?
   performance-metric-normality
            |  |     +--ro unidirectional-packet-loss?
   performance-metric-normality
            |  |     +--ro unidirectional-residual-bandwidth?
   performance-metric-normality
            |  |     +--ro unidirectional-available-bandwidth?
   performance-metric-normality
            |  |     +--ro unidirectional-utilized-bandwidth?
   performance-metric-normality
            |  +--ro link-protection-type?             enumeration
            |  +--ro interface-switching-capabilities*
    [switching-capability] interface-switching-capability* [switching-
   capability]
            |  |  +--ro switching-capability               identityref
            |  |  +--ro encoding?                          identityref
            |  |  +--ro max-lsp-bandwidth* [priority]
            |  |  |  +--ro priority     uint8
            |  |  |  +--ro bandwidth?   decimal64
            |  |  +--ro packet-switch-capable
            |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
            |  |  |  +--ro interface-mtu?           uint16
            |  |  +--ro time-division-multiplex-capable
            |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
            |  |  |  +--ro indication?              enumeration
            |  |  +--ro te-srlgs
                         +--ro values*   te-types:srlg
    notifications:
       +---n te-node-event interface-adjustment-capability* [upper-sc]
            |  |     +--ro event-type?           te-topology-event-type upper-sc             identityref
            |  |     +--ro provider-id-ref?      leafref upper-encoding?      identityref
            |  |     +--ro client-id-ref?        leafref max-lsp-bandwidth* [priority]
            |  |        +--ro topology-id-ref?      leafref priority     uint8
            |  |        +--ro node-ref?             leafref bandwidth?   decimal64
            |  +--ro te-topology! te-srlgs
            |     +--ro te-node-attributes values*   te-types:srlg
            +--ro recovery
            |  +--ro restoration-status?   te-recovery-status
            |  +--ro schedules* [schedule-id] {configuration-schedule}? protection-status?    te-recovery-status
            +--ro underlay {te-topology-hierarchy}?
               +--ro dynamic?     boolean
               +--ro committed?   boolean
   augment /nw:network/nw:node/nt:termination-point:
      +--rw te!
         +--rw te-tp-id    te-tp-id
         +--rw config
         |  +--rw schedules
         |     +--rw schedule* [schedule-id]
         |  +--ro        +--rw schedule-id          uint32
         |        +--rw start?               yang:date-and-time
         |        +--rw schedule-duration?   string
         |        +--rw repeat-interval?     string
         +--ro state
            +--ro schedules
               +--ro schedule* [schedule-id]
                  +--ro schedule-id          uint32
                  +--ro start?               yang:date-and-time
       |  |  |
                  +--ro schedule-duration?   string
       |  |  |
                  +--ro repeat-interval?     string
       |
   notifications:
      +---n te-node-event
      |  +--ro name?                  inet:domain-name
       | event-type?                 te-topology-event-type
      |  +--ro signaling-address*     inet:ip-address
       | node-ref?                   leafref
      |  +--ro flag*                  flag-type network-ref?                leafref
      |  +--ro te-topology!
      |  +--ro is-abstract?           boolean te-node-attributes
      |  |  +--ro underlay-topology {te-topology-hierarchy}? schedules
      |  |  |  +--ro provider-id-ref?   leafref schedule* [schedule-id]
      |  |  |     +--ro client-id-ref?     leafref schedule-id          uint32
      |  |  |     +--ro topology-id-ref?   leafref start?               yang:date-and-time
      |  |  |     +--ro connectivity-matrix* [id] schedule-duration?   string
      |  |  |     +--ro id            uint32 repeat-interval?     string
      |  |  +--ro from-link
       | admin-status?          te-admin-status
      |  |  +--ro provider-id-ref?   leafref connectivity-matrix* [id]
      |  |  |  +--ro client-id-ref?     leafref id            uint32
      |  |  |  +--ro topology-id-ref?   leafref from
      |  |  |  |  +--ro node-ref? tp-ref?        leafref
      |  |  |  |  +--ro link-end-ref? node-ref?      leafref
      |  |     +--ro to-link
       |  |  |  +--ro provider-id-ref? network-ref?   leafref
      |  |  |  +--ro client-id-ref?     leafref to
      |  |  |  |  +--ro topology-id-ref? tp-ref?        leafref
      |  |  |  |  +--ro node-ref?      leafref
      |  |  |  |  +--ro link-end-ref? network-ref?   leafref
      |  |  |  +--ro is-allowed?   boolean
      |  +--ro te-link* [te-link-id]
       |  |  +--ro te-link-id         te-link-id domain-id?             uint32
      |  |  +--ro (stack-level)?
       | flag*                  te-node-flag
      |     +--:(bundle)  |  +--ro is-abstract?           empty
      |  |  +--ro bundled-links
       | name?                  inet:domain-name
      |  |  +--ro bundled-link* [sequence]
       | signaling-address*     inet:ip-address
      |  |  +--ro sequence       uint32
       | underlay-topology {te-topology-hierarchy}?
      |  |     +--ro te-link-ref? provider-id-ref?      leafref
      |  |     +--:(component)
       |  |     +--ro component-links client-id-ref?        leafref
      |  |     +--ro component-link* [sequence] te-topology-id-ref?   leafref
      |  |     +--ro sequence              uint32
       | network-id-ref?       leafref
      |  +--ro component-link-ref?   leafref oper-status?                te-oper-status
      |  +--ro te-node-state is-multi-access-dr?         empty
      |  +--ro information-source?         enumeration
      |  +--ro information-source-state
      |     +--ro credibility-preference?   uint16
      |     +--ro topology
      |     |  +--ro provider-id-ref?      leafref
      |     |  +--ro client-id-ref?        leafref
      |     |  +--ro topology-id-ref? te-topology-id-ref?   leafref
      |     |  +--ro network-id-ref?       leafref
      |     +--ro routing-instance?         string
      +---n te-link-event
         +--ro event-type?                 te-topology-event-type
         +--ro provider-id-ref?         leafref
          +--ro client-id-ref?           leafref
          +--ro topology-id-ref?         leafref
          +--ro source-te-node-id-ref?   leafref
          +--ro source-te-link-id-ref?   leafref
          +--ro dest-te-node-id-ref? link-ref?                   leafref
         +--ro dest-te-link-id-ref? network-ref?                leafref
         +--ro te-topology!
         +--ro te-link-attributes
         |  +--ro schedules* schedules
         |  |  +--ro schedule* [schedule-id] {configuration-schedule}?
         |  |     +--ro schedule-id          uint32
         |  |     +--ro start?               yang:date-and-time
         |  |     +--ro schedule-duration?   string
         |  |     +--ro repeat-interval?     string
         |  +--ro name?                               string access-type?                      te-link-access-type
         |  +--ro flag*                               flag-type                             te-link-flag
         |  +--ro is-abstract?                        boolean                      empty
         |  +--ro name?                             string
         |  +--ro underlay! {te-topology-hierarchy}?
         |  |  +--ro underlay-primary-path
         |  |  |  +--ro provider-id-ref?      leafref
         |  |  |  +--ro client-id-ref?        leafref
         |  |  |  +--ro topology-id-ref? te-topology-id-ref?   leafref
         |  |  |  +--ro network-id-ref?       leafref
         |  |  |  +--ro path-element* [path-element-id]
         |  |  |     +--ro path-element-id     uint32
         |  |  |     +--ro (type)?
         |  |  |        +--:(ipv4-address)
         |  |  |        |  +--ro v4-address?         inet:ipv4-address
         |  |  |        |  +--ro v4-prefix-length?   uint8
         |  |  |        |  +--ro v4-loose?           boolean
         |  |  |        +--:(ipv6-address)
         |  |  |        |  +--ro v6-address?         inet:ipv6-address
         |  |  |        |  +--ro v6-prefix-length?   uint8
         |  |  |        |  +--ro v6-loose?           boolean
         |  |  |        +--:(as-number)
         |  |  |        |  +--ro as-number?          uint16
         |  |  |        +--:(unnumbered-link)
         |  |  |        |  +--ro router-id?          inet:ip-address
         |  |  |        |  +--ro interface-id?       uint32
         |  |  |        +--:(label)
         |  |  |           +--ro value?              uint32
         |  |  +--ro underlay-backup-path* [index]
         |  |  |  +--ro index                 uint32
         |  |  |  +--ro provider-id-ref?      leafref
         |  |  |  +--ro client-id-ref?        leafref
         |  |  |  +--ro topology-id-ref? te-topology-id-ref?   leafref
         |  |  |  +--ro network-id-ref?       leafref
         |  |  |  +--ro path-element* [path-element-id]
         |  |  |     +--ro path-element-id     uint32
         |  |  |     +--ro (type)?
         |  |  |        +--:(ipv4-address)
         |  |  |        |  +--ro v4-address?         inet:ipv4-address
         |  |  |        |  +--ro v4-prefix-length?   uint8
         |  |  |        |  +--ro v4-loose?           boolean
         |  |  |        +--:(ipv6-address)
         |  |  |        |  +--ro v6-address?         inet:ipv6-address
         |  |  |        |  +--ro v6-prefix-length?   uint8
         |  |  |        |  +--ro v6-loose?           boolean
         |  |  |        +--:(as-number)
         |  |  |        |  +--ro as-number?          uint16
         |  |  |        +--:(unnumbered-link)
         |  |  |        |  +--ro router-id?          inet:ip-address
         |  |  |        |  +--ro interface-id?       uint32
         |  |  |        +--:(label)
         |  |  |           +--ro value?              uint32
         |  |  +--ro underlay-protection-type?   uint16
         |  |  +--ro underlay-trail-src
         |  |  |  +--ro provider-id-ref? tp-ref?        leafref
         |  |  |  +--ro client-id-ref? node-ref?      leafref
         |  |  |  +--ro topology-id-ref?   leafref
          |  |  |  +--ro node-ref?          leafref
          |  |  |  +--ro link-end-ref? network-ref?   leafref
         |  |  +--ro underlay-trail-des
         |  |  |  +--ro provider-id-ref?   leafref
          |  |  |  +--ro client-id-ref?     leafref
          |  |  |  +--ro topology-id-ref? tp-ref?        leafref
         |  |  |  +--ro node-ref?      leafref
         |  |  |  +--ro link-end-ref? network-ref?   leafref
         |  |  +--ro dynamic?                    boolean
         |  |  +--ro committed?                  boolean
         |  +--ro admin-status?                       enumeration                     te-admin-status
         |  +--ro performance-metric-throttle {te-performance-metric}?
         |  |  +--ro unidirectional-delay-offset?           uint32
         |  |  +--ro measure-interval?                      uint32
         |  |  +--ro advertisement-interval?                uint32
         |  |  +--ro suppression-interval?                  uint32
         |  |  +--ro threshold-out
         |  |  |  +--ro unidirectional-delay?                 uint32
         |  |  |  +--ro unidirectional-min-delay?             uint32
         |  |  |  +--ro unidirectional-max-delay?             uint32
         |  |  |  +--ro unidirectional-delay-variation?       uint32
         |  |  |  +--ro unidirectional-packet-loss?           decimal64
         |  |  |  +--ro unidirectional-residual-bandwidth?    decimal64
         |  |  |  +--ro unidirectional-available-bandwidth?   decimal64
         |  |  |  +--ro unidirectional-utilized-bandwidth?    decimal64
         |  |  +--ro threshold-in
         |  |  |  +--ro unidirectional-delay?                 uint32
         |  |  |  +--ro unidirectional-min-delay?             uint32
         |  |  |  +--ro unidirectional-max-delay?             uint32
         |  |  |  +--ro unidirectional-delay-variation?       uint32
         |  |  |  +--ro unidirectional-packet-loss?           decimal64
         |  |  |  +--ro unidirectional-residual-bandwidth?    decimal64
         |  |  |  +--ro unidirectional-available-bandwidth?   decimal64
         |  |  |  +--ro unidirectional-utilized-bandwidth?    decimal64
         |  |  +--ro threshold-accelerated-advertisement
         |  |     +--ro unidirectional-delay?                 uint32
         |  |     +--ro unidirectional-min-delay?             uint32
         |  |     +--ro unidirectional-max-delay?             uint32
         |  |     +--ro unidirectional-delay-variation?       uint32
         |  |     +--ro unidirectional-packet-loss?           decimal64
         |  |     +--ro unidirectional-residual-bandwidth?    decimal64
         |  |     +--ro unidirectional-available-bandwidth?   decimal64
         |  |     +--ro unidirectional-utilized-bandwidth?    decimal64
         |  +--ro link-index?                       uint64
         |  +--ro administrative-group?             te-types:admin-
   groups
         |  +--ro max-link-bandwidth?               decimal64
         |  +--ro max-resv-link-bandwidth?          decimal64
         |  +--ro unreserved-bandwidth* [priority]
         |  |  +--ro priority     uint8
         |  |  +--ro bandwidth?   decimal64
         |  +--ro te-default-metric?                uint32
         |  +--ro performance-metric {te-performance-metric}?
         |  |  +--ro measurement
         |  |  |  +--ro unidirectional-delay?                 uint32
         |  |  |  +--ro unidirectional-min-delay?             uint32
         |  |  |  +--ro unidirectional-max-delay?             uint32
         |  |  |  +--ro unidirectional-delay-variation?       uint32
         |  |  |  +--ro unidirectional-packet-loss?           decimal64
         |  |  |  +--ro unidirectional-residual-bandwidth?    decimal64
         |  |  |  +--ro unidirectional-available-bandwidth?   decimal64
         |  |  |  +--ro unidirectional-utilized-bandwidth?    decimal64
         |  |  +--ro normality
         |  |     +--ro unidirectional-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-min-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-max-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-delay-variation?
   performance-metric-normality
         |  |     +--ro unidirectional-packet-loss?
   performance-metric-normality
         |  |     +--ro unidirectional-residual-bandwidth?
   performance-metric-normality
         |  |     +--ro unidirectional-available-bandwidth?
   performance-metric-normality
         |  |     +--ro unidirectional-utilized-bandwidth?
   performance-metric-normality
         |  +--ro link-protection-type?             enumeration
         |  +--ro interface-switching-capabilities* interface-switching-capability* [switching-
   capability]
         |  |  +--ro switching-capability               identityref
         |  |  +--ro encoding?                          identityref
         |  |  +--ro max-lsp-bandwidth* [priority]
         |  |  |  +--ro priority     uint8
         |  |  |  +--ro bandwidth?   decimal64
         |  |  +--ro packet-switch-capable
         |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
         |  |  |  +--ro interface-mtu?           uint16
         |  |  +--ro time-division-multiplex-capable
         |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
         |  |  |  +--ro indication?              enumeration
         |  |  +--ro interface-adjustment-capability* [upper-sc]
         |  |     +--ro upper-sc             identityref
         |  |     +--ro upper-encoding?      identityref
         |  |     +--ro max-lsp-bandwidth* [priority]
         |  |        +--ro priority     uint8
         |  |        +--ro bandwidth?   decimal64
         |  +--ro te-srlgs
         |     +--ro values*   te-types:srlg
         +--ro te-link-state
             +--ro oper-status?                enumeration                te-oper-status
         +--ro information-source?         enumeration
         +--ro information-source-state
         |  +--ro credibility-preference?   uint16
         |  +--ro topology
         |  |  +--ro provider-id-ref?      leafref
         |  |  +--ro client-id-ref?        leafref
         |  |  +--ro topology-id-ref? te-topology-id-ref?   leafref
         |  |  +--ro network-id-ref?       leafref
         |  +--ro routing-instance?         string
         +--ro alt-information-sources* [information-source]
         |  +--ro information-source                enumeration
         |  +--ro information-source-state
         |  |  +--ro credibility-preference?   uint16
         |  |  +--ro topology
         |  |  |  +--ro provider-id-ref?      leafref
         |  |  |  +--ro client-id-ref?        leafref
         |  |  |  +--ro te-topology-id-ref?   leafref
         |  |  |  +--ro topology-id-ref? network-id-ref?       leafref
         |  |  +--ro routing-instance?         string
         |  +--ro link-index?                       uint64
         |  +--ro administrative-group?               te-
    types:admin-groups             te-types:admin-
   groups
         |  +--ro max-link-bandwidth?               decimal64
         |  +--ro max-resv-link-bandwidth?          decimal64
         |  +--ro unreserved-bandwidth* [priority]
         |  |  +--ro priority     uint8
         |  |  +--ro bandwidth?   decimal64
         |  +--ro te-default-metric?                uint32
         |  +--ro performance-metric {te-performance-metric}?
         |  |  +--ro measurement
         |  |  |  +--ro unidirectional-delay?                 uint32
         |  |  |  +--ro unidirectional-min-delay?             uint32
         |  |  |  +--ro unidirectional-max-delay?             uint32
         |  |  |  +--ro unidirectional-delay-variation?       uint32
         |  |  |  +--ro unidirectional-packet-loss?           decimal64
         |  |  |  +--ro unidirectional-residual-bandwidth?    decimal64
         |  |  |  +--ro unidirectional-available-bandwidth?   decimal64
         |  |  |  +--ro unidirectional-utilized-bandwidth?    decimal64
         |  |  +--ro normality
         |  |     +--ro unidirectional-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-min-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-max-delay?
   performance-metric-normality
         |  |     +--ro unidirectional-delay-variation?
   performance-metric-normality
         |  |     +--ro unidirectional-packet-loss?
   performance-metric-normality
         |  |     +--ro unidirectional-residual-bandwidth?
   performance-metric-normality
         |  |     +--ro unidirectional-available-bandwidth?
   performance-metric-normality
         |  |     +--ro unidirectional-utilized-bandwidth?
   performance-metric-normality
         |  +--ro link-protection-type?             enumeration
         |  +--ro interface-switching-capabilities* interface-switching-capability* [switching-
   capability]
         |  |  +--ro switching-capability               identityref
         |  |  +--ro encoding?                          identityref
         |  |  +--ro max-lsp-bandwidth* [priority]
         |  |  |  +--ro priority     uint8
         |  |  |  +--ro bandwidth?   decimal64
         |  |  +--ro packet-switch-capable
         |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
         |  |  |  +--ro interface-mtu?           uint16
         |  |  +--ro time-division-multiplex-capable
         |  |  |  +--ro minimum-lsp-bandwidth?   decimal64
         |  |  |  +--ro indication?              enumeration
         |  |  +--ro interface-adjustment-capability* [upper-sc]
         |  |     +--ro upper-sc             identityref
         |  |     +--ro upper-encoding?      identityref
         |  |     +--ro max-lsp-bandwidth* [priority]
         |  |        +--ro priority     uint8
         |  |        +--ro bandwidth?   decimal64
         |  +--ro te-srlgs
         |     +--ro values*   te-types:srlg
         +--ro recovery
         |  +--ro restoration-status?   te-recovery-status
         |  +--ro protection-status?    te-recovery-status
         +--ro underlay {te-topology-hierarchy}?
            +--ro dynamic?     boolean
            +--ro committed?   boolean

6. TE Topology Yang Module

   <CODE BEGINS>

   module ietf-te-topology {
     yang-version 1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology";
     // replace with IANA namespace when assigned

     prefix "tet";

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

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

     import ietf-interfaces ietf-schedule {
       prefix "if"; "sch";
     }

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

     import ietf-network {
       prefix "nw";
     }

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

     organization "TBD";
     contact "TBD";
     description "TE topology model";

     revision "2015-07-02" "2015-10-16" {
       description "Initial revision";
       reference "TBD";
     }

     /*
      * Features
      */

     feature configuration-schedule {
       description
         "This feature indicates that the system supports
          configuration scheduling.";
     }

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

     feature te-performance-metric {
       description
         "This feature indicates that the system supports
          TE performance metric defined in
          draft-ietf-ospf-te-metric-extensions.";
      }

      feature configuration-schedule {
        description
          "This feature indicates that the system supports
          configuration scheduling.";
          RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
     }

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

     /*
      * Typedefs
      */
     typedef te-global-id performance-metric-normality {
       type uint32; enumeration {
         enum "unknown" {
           value 0;
           description
          "An identifier to uniquely identify an operator, which can be
          either a provider or a client.
             "Unknown.";
         }
         enum "normal" {
           value 1;
           description
             "Normal.";
         }
         enum "abnormal" {
           value 2;
           description
             "Abnormal. The definition of this type anomalous bit is taken from RFC6370 and RFC503. set.";
         }
       }
       description
         "Indicates whether a performance metric is normal, abnormal,
          or unknown.";
       reference
         "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
     }

     typedef te-admin-status {
       type enumeration {
         enum up {
           description
             "Enabled.";
         }
         enum down {
           description
             "Disabled.";
         }
         enum testing {
           description
             "In some test mode.";
         }
         enum preparing-maintenance {
           description
             "Resource is disabled in the control plane to prepare for
              graceful shutdown for maintenance purposes.";
           reference
             "RFC5817: Graceful Shutdown in MPLS and Generalized MPLS
              Traffic Engineering Networks";
         }
         enum maintenance {
           description
             "Resource is disabled in the data plane for maintenance
              purposes.";
         }
       }
       description
         "Defines a type representing the administrative status of
          a TE resource.";
     }

     typedef te-global-id {
       type uint32;
       description
         "An identifier to uniquely identify an operator, which can be
          either a provider or a client.
          The definition of this type is taken from RFC6370 and
          RFC5003. This attribute type is used solely to provide a
          globally unique context for TE topologies.";

     }

     typedef te-topology-id te-link-access-type {
       type string enumeration {
         enum point-to-point {
          pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
        }
           description
          "An identifier for a topology.";
             "The link is point-to-point.";
         }

      typedef te-template-name {
        type string
         enum multi-access {
          pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
           description
             "The link is multi-access, including broacast and NBMA.";
         }
       }
       description
          "A
         "Defines a type for representing the name access type of a TE node template or TE link
          template."; link.";
       reference
         "RFC3630: Traffic Engineering (TE) Extensions to OSPF
          Version 2.";
     }

     typedef te-node-id {
       type inet:ip-address;
       description
         "An identifier for a node in a topology.
          The identifier is represented as an IPv4 or IPv6 address.
           The identifier SHOULD be chosen such that the same node in a
           real network topology will always be identified through the
           same identifier, even if the model
          This attribute is instantiated in
           separate
           datastores. An implementation MAY choose mapped to capture semantics Router ID in the identifier, for example to indicate the type of node
           and/or the type of topology that the node is a part of.";
          RFC3630, RFC5329, RFC5305, and RFC 6119.";
     }

     typedef te-link-id te-oper-status {
       type union enumeration {
          type uint32;          // Unnumbered
          type inet:ip-address; // IPv4 or IPv6 address
         enum up {
           description
           "Operational up.";
         }
         enum down {
           description
          "An identifier for a TE link on a node.
           The identifier may be opaque.
           The identifier SHOULD be chosen such that the same TP in a
           real network topology will always
           "Operational down.";
         }
         enum testing {
           description
           "In some test mode.";
         }
         enum unknown {
           description
           "Status cannot be identified through the
           same identifier, even if the model determined for some reason.";

         }
         enum preparing-maintenance {
           description
             "Resource is instantiated disabled in
           separate
           datastores. An implementation MAY choose the control plane to capture semantics prepare for
              graceful shutdown for maintenance purposes.";
           reference
             "RFC5817: Graceful Shutdown in MPLS and Generalized MPLS
              Traffic Engineering Networks";
         }
         enum maintenance {
           description
             "Resource is disabled in the identifier, data plane for example to indicate maintenance
              purposes.";
         }
       }
       description
         "Defines a type representing the operational status of
          a TE resource.";
     }

     typedef te-recovery-status {
       type enumeration {
         enum normal {
           description
             "Both the recovery and working spans are fully
              allocated and active, data traffic is being
              transported over (or selected from) the working
              span, and no trigger events are reported.";
         }
         enum recovery-started {
           description
             "The recovery action has been started, but not
              completed.";
         }
         enum recovery-succeeded {
           description
             "The recovery action has succeeded. The working span has
              reported a failure/degrade condition and the user traffic
              is being transported (or selected) on the recovery
              span.";
         }
         enum recovery-failed {
           description
             "The recovery action has failed.";
         }
         enum reversion-started {
           description
             "The reversion has started.";
         }
         enum reversion-failed {
           description
             "The reversion has failed.";
         }
         enum recovery-unavailable {
           description
             "The recovery is unavailable -- either as a result of TP
           and/or an
              operator Lockout command or a failure condition detected
              on the type recovery span.";
         }
         enum recovery-admin {
           description
             "The operator has issued a command switching the user
              traffic to the recovery span.";
         }
         enum wait-to-restore {
           description
             "The recovery domain is recovering from a failuer/degrade
              condition on the working span that is being controlled by
              the Wait-to-Restore (WTR) timer.";
         }
       }
       description
         "Defines the status of node a recovery action.";
       reference
         "RFC4427: Recovery (Protection and topology that Restoration) Terminology
          for Generalized Multi-Protocol Label Switching (GMPLS).
          RFC6378: MPLS Transport Profile (MPLS-TP) Linear Protection";
     }

     typedef te-template-name {
       type string {
         pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
       }
       description
         "A type for the TP is name of a part
           of."; TE node template or TE link
          template.";
     }

     typedef te-topology-event-type {
       type enumeration {
         enum "add" {
           value 0;
           description
             "A TE node or te-link has been added"; added.";
         }
         enum "remove" {
           value 1;
           description
             "A TE node or te-link has been removed"; removed.";
         }
         enum "update" {
           value 2;
           description
             "A TE node or te-link has been updated"; updated.";
         }
       }
       description "TE  Event type for notifications";
     } // te-topology-event-type

     typedef performance-metric-normality te-topology-id {
       type enumeration {
          enum "unknown" string {
            value 0;
            description
              "Unknown";
         pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
       }
          enum "normal" {
            value 1;
       description
              "Normal";
          }
          enum "abnormal" {
            value 2;
            description
              "Abnormal. The anomalous bit is set.";
         "An identifier for a topology.";
     }

     typedef te-tp-id {
       type union {
         type uint32;          // Unnumbered
         type inet:ip-address; // IPv4 or IPv6 address
       }
       description
          "Indicates whether
         "An identifier for a performance metric TE link endpoint on a node.
          This attribute is normal, abnormal, mapped to local or unknown."; remote link identifier
          in RFC3630 and RFC5305.";
     }

     /*
      * Identities
      */

     identity flag-identity te-flag-base {
       description "Base type for flags"; flags.";
     }

     identity te-link-flag {
       base "te-flag-base";
       description "TE link flag.";
     }

     identity undefined-flag te-node-flag {
       base "flag-identity"; "te-flag-base";
       description "TE node flag.";
     }

     identity te-undefined-flag {
       base "te-flag-base";
       description "Undefined flag"; flag.";
     }

     typedef te-node-flag {
       type identityref {
         base "te-node-flag";
       }
       description "Type for TE node flags.";
     }

     typedef flag-type te-link-flag {
       type identityref {
         base "flag-identity"; "te-link-flag";
       }
       description "Type for flags"; TE link flags.";
     }

     /*
      * Groupings
      */
     grouping topo-ref network-ref {
       description
          "Grouping for an absolute reference
         "Contains the information necessary to reference a topology instance."; network,
          for example an underlay network.";
       leaf provider-id-ref network-ref {
         type leafref {
           path "/tet:te-topologies/tet:topology/tet:provider-id"; "/nw:network/nw:network-id";
         }
         description
            "An absolute reference
           "Used to reference a provider-id."; network, for example an underlay
            network.";
       }
        leaf client-id-ref {
          type leafref {
            path "/tet:te-topologies/tet:topology/tet:client-id";
     }

     grouping node-ref {
       description
            "An absolute reference
         "Contains the information necessary to reference a client-id.";
        } node.";
       leaf topology-id-ref node-ref {
         type leafref {
           path "/tet:te-topologies/tet:topology/tet:te-topology-id"; "/nw:network[nw:network-id=current()/../network-ref]"+
             "/nw:node/nw:node-id";
         }
         description
            "An absolute reference
           "Used to reference a te-topology-id."; node.
            Nodes are identified relative to the network they are
            contained in.";
       }
       uses network-ref;
     } // topo-ref

     grouping link-ref {
       description
          "Grouping for an absolute reference to
         "References a link instance.";
        uses topo-ref; in a specific network.";
       leaf source-te-node-id-ref link-ref {
         type leafref {
           path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:link/tet:source-te-node-id"; "/nw:network[nw:network-id=current()/../"+
             "network-ref]/nt:link/nt:link-id";
         }
         description
            "An
           "A type for an absolute reference to a link instance.";
        }
        leaf source-te-link-id-ref { instance.
            (This type leafref { should not be used for relative references.
            In such a case, a relative path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:link/tet:source-te-link-id"; should be used instead.)";
       }
          description
            "An absolute reference to a link instance.";
       uses network-ref;
     }
        leaf dest-te-node-id-ref {
          type leafref

     grouping tp-ref {
            path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:link/tet:dest-te-node-id";
          }
       description
            "An absolute reference to
         "References a link instance.";
        } termination point in a specific node.";
       leaf dest-te-link-id-ref tp-ref {
         type leafref {
           path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:link/tet:dest-te-link-id";
          }
          description
            "An absolute reference to a link instance.";
        } "/nw:network[nw:network-id=current()/../"+
             "network-ref]/nw:node[nw:node-id=current()/../"+
             "node-ref]/nt:termination-point/nt:tp-id";
         } // link-ref

      grouping node-ref {
         description
          "Grouping
           "A type for an absolute reference to a node instance.";
        uses topo-ref;
        leaf node-ref { termination point.
            (This type leafref { should not be used for relative references.
            In such a case, a relative path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:node/tet:te-node-id"; should be used instead.)";
       }
          description
            "An absolute reference to a node instance.";
        }
      } // node-ref

      grouping link-end-ref {
        description
          "Grouping for an absolute reference to a TE link end, which is
          the local representation of a TE link on a node.";
       uses node-ref;
        leaf link-end-ref {
          type leafref {
            path "/tet:te-topologies/tet:topology"
              +"[tet:provider-id = current()/../provider-id-ref]"
              +"[tet:client-id = current()/../client-id-ref]"
              +"[tet:te-topology-id = current()/../topology-id-ref]"
              +"/tet:node[tet:te-node-id = current()/../node-ref]"
              +"/tet:te-link/tet:te-link-id";
          }
          description
            "Grouping for an absolute reference to a TE link end.";
        }
      } // link-end-ref

      grouping te-topology-type {
        description
          "Identifies the TE topology type.";
        container te-topology {
          presence "indicates TE topology";
          description
            "Its presence identifies the TE topology type.";
        }
      } // te-topology-type

      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-subobject;
      } // te-path-element

      grouping config-schedule-attributes {
        description
          "A list of schedules defining when a particular
           configuration takes effect.";
        list schedules {
          if-feature configuration-schedule;
          key "schedule-id";
          description "A list of schedule elements.";

          leaf schedule-id {
            type uint32;
            description "Identifies the schedule element.";
          }
          leaf start {
            type yang:date-and-time;
            description "Start time.";

          }
          leaf schedule-duration {
            type string {
              pattern
                'P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?(\d+S)?';
            }
            description "Schedule duration in ISO 8601 format.";
          }
          leaf repeat-interval {
            type string {
              pattern
                'R\d*/P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?'
                + '(\d+S)?';
            }
            description "Repeat interval in ISO 8601 format.";
         }
        }
     } // config-schedule-attributes
     grouping information-source-attributes {
       description
         "The attributes identifying source that has provided the
          related information, and the source credibility.";
       leaf information-source {
         type enumeration {
           enum "unknown" {
             description "The source is unknown"; unknown.";
           }
           enum "locally-configured" {
             description "Configured entity"; entity.";
           }
           enum "ospfv2" {
             description "OSPFv2"; "OSPFv2.";
           }
           enum "ospfv3" {
             description "OSPFv3"; "OSPFv3.";
           }
           enum "isis" {
             description "ISIS"; "ISIS.";
           }
           enum "system-processed" {
             description "System processed entity.";
           }
           enum "other" {
             description "Other source"; source.";
           }
         }
         description
           "Indicates the source of the information.";
       }
       container information-source-state {
         description
           "The container contains state attributes related to
            the information source.";
         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.";
         }
         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.";
            leaf provider-id-ref {
              type leafref {
                path "/tet:te-topologies/tet:topology/tet:provider-id";
              }
              description
                "A reference to a provider-id.";
            }
            leaf client-id-ref {
              type leafref {
                path "/tet:te-topologies/tet:topology/tet:client-id";
              }
              description
                "A reference to a client-id.";
            }
            leaf topology-id-ref {
              type leafref {
                path "/tet:te-topologies/tet:topology"
                  +"/tet:te-topology-id";
              }
              description
                "A reference to a te-topology-id.";
            }
           uses te-topology-ref;
         } // topology
         leaf routing-instance {
           type string;
           description
             "When applicable, this is the name of a routing instance
              from which the information is learned.";
         } // routing-information
       }
     } // information-source-attributes

     grouping te-node-attributes performance-metric-attributes {
       description "Node attributes
         "Link performance information in a TE topology.";
        container te-node-attributes {
          description "Node attributes in a TE topology.";
          uses config-schedule-attributes; real time.";
       reference
         "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
       leaf name unidirectional-delay {
         type inet:domain-name;
            description "Node name.";
          }
          leaf-list signaling-address uint32 {
            type inet:ip-address;
            description "Node signaling address.";
           range 0..16777215;
         }
          leaf-list flag {
            type flag-type;
         description "Node operational flags."; "Delay or latency in micro seconds.";
       }
       leaf is-abstract unidirectional-min-delay {
         type boolean;
            description
              "true if the node is abstract, false when the node is
              actual.";
          }
          container underlay-topology uint32 {
            if-feature te-topology-hierarchy;
           range 0..16777215;
         }
         description
              "When an abstract node encapsulates a topology,
              the attributes "Minimum delay or latency in this container point to said topology."; micro seconds.";
       }
       leaf provider-id-ref unidirectional-max-delay {
         type leafref uint32 {
                path "/tet:te-topologies/tet:topology/tet:provider-id";
           range 0..16777215;
         }
         description
                "A reference to a provider-id."; "Maximum delay or latency in micro seconds.";
       }
       leaf client-id-ref unidirectional-delay-variation {
         type leafref uint32 {
                path "/tet:te-topologies/tet:topology/tet:client-id";
           range 0..16777215;
         }
         description
                "A reference to a client-id."; "Delay variation in micro seconds.";
       }
       leaf topology-id-ref unidirectional-packet-loss {
         type leafref decimal64 {
                path "/tet:te-topologies/tet:topology"
                  +"/tet:te-topology-id";
           fraction-digits 6;
           range "0 .. 50.331642";
         }
         description
                "A reference to
           "Packet loss as a te-topology-id.";
            }
          }

          list connectivity-matrix {
            key "id";
            description
              "Represents node's switching limitations, i.e. limitations
               in interconnecting network TE links across percentage of the node."; total traffic sent
            over a configurable interval. The finest precision is
            0.000003%.";
       }
       leaf id unidirectional-residual-bandwidth {
         type uint32;
              description "Identifies the connectivity-matrix entry.";
            }
            container from-link decimal64 {
              uses tet:link-end-ref;
              description
                "Reference to source NTP.";
           fraction-digits 2;
         }
            container to-link {
              uses tet:link-end-ref;
         description
                "Reference to destination NTP.";
           "Residual bandwidth that subtracts tunnel
            reservations from Maximum Bandwidth (or link capacity)
            [RFC3630] and provides an aggregated remainder across QoS
            classes.";
       }
       leaf is-allowed unidirectional-available-bandwidth {
         type boolean;
              description
                "true  - switching is allowed,
                 false - switching is disallowed.";
            }
          }
        }
        list te-link decimal64 {
          key "te-link-id";
           fraction-digits 2;
         }
         description
            "The local representation
           "Available bandwidth that is defined to be residual
            bandwidth minus the measured bandwidth used for the
            actual forwarding of non-RSVP-TE LSP packets.  For a TE
            bundled link, which
            interconnect TE nodes."; available bandwidth is defined to be the
            sum of the component link available bandwidths.";
       }
       leaf te-link-id unidirectional-utilized-bandwidth {
         type te-link-id;
            description
              "TE link identifier.";
          }
          choice stack-level decimal64 {
           fraction-digits 2;
         }
         description
              "The TE
           "Bandwidth utilization that represents the actual
            utilization of the link can be partitioned into (i.e. as measured in the router).
            For a bundled
              links, or link, bandwidth utilization is defined to
            be the sum of the component links.";
            case bundle {
              container bundled-links link bandwidth
            utilizations.";
       }
     } // performance-metric-attributes

     grouping performance-metric-normality-attributes {
       description
                  "A set of bundled links";
                list bundled-link
         "Link performance metric normality attributes.";
       reference
         "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
       leaf unidirectional-delay {
                  key "sequence";
         type performance-metric-normality;
         description
                    "Specify a bundled interface that is
                    further partitioned."; "Delay normality.";
       }
       leaf sequence unidirectional-min-delay {
         type uint32; performance-metric-normality;
         description
                      "Identify the sequence in the bundle."; "Minimum delay or latency normality.";
       }
       leaf te-link-ref unidirectional-max-delay {
         type leafref {
                      path "../../../te-link-id";
                      require-instance true;
                    } performance-metric-normality;
         description
                      "Reference to TE link on this node.";
                  }
                }
              } "Maximum delay or latency normality.";
       }
            case component {
              container component-links
       leaf unidirectional-delay-variation {
         type performance-metric-normality;
         description
                  "A set of component links";
                list component-link "Delay variation normality.";
       }
       leaf unidirectional-packet-loss {
                  key "sequence";
         type performance-metric-normality;
         description
                    "Specify a component interface that is
                    sufficient to unambiguously identify the
                    appropriate resources"; "Packet loss normality.";
       }
       leaf sequence unidirectional-residual-bandwidth {
         type uint32; performance-metric-normality;
         description
                      "Identify the sequence in the bundle."; "Residual bandwidth normality.";
       }
       leaf component-link-ref unidirectional-available-bandwidth {
         type leafref {
                      path "/if:interfaces/if:interface/if:name";
                      require-instance false;
                    } performance-metric-normality;
         description
                      "Reference to component link on this
                      node.";
                  }
                }
              }
            }
          }
        } "Available bandwidth normality.";
       } // te-node-attributes

      grouping te-node-state-attributes {
        description "Node state attributes in a TE topology.";
        container te-node-state
       leaf unidirectional-utilized-bandwidth {
         type performance-metric-normality;
         description "Node state attributes in a TE topology.";
          uses information-source-attributes; "Bandwidth utilization normality.";
       }
     } // te-node-state-attributes performance-metric-normality-attributes

     grouping te-link-underlay-attributes performance-metric-throttle-container {
       description "Attributes for  te-link underlay.";
         "A container underlay-primary-path controlling performance metric throttle.";
       container performance-metric-throttle {
         if-feature te-performance-metric;
         must "suppression-interval >= measure-interval" {
           error-message
             "suppression-interval cannot be less then
              measure-interval.";
           description
            "The service path
             "Constraint on the underlay topology that
             supports this link.";
          leaf provider-id-ref {
            type leafref {
              path "/tet:te-topologies/tet:topology/tet:provider-id";
              require-instance false; suppression-interval and
              measure-interval.";
         }
         description
              "A
           "Link performance information in real time.";
         reference to a provider-id.";
          }
           "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
         leaf client-id-ref unidirectional-delay-offset {
           type leafref uint32 {
              path "/tet:te-topologies/tet:topology/tet:client-id";
              require-instance false;
             range 0..16777215;
           }
           description
              "A reference
             "Offset value to be added to a client-id.";
          }
          leaf topology-id-ref {
            type leafref {
              path "/tet:te-topologies/tet:topology/tet:te-topology-id";
              require-instance false;
            }
            description
              "Identifies the topology where the path belongs."; measured delay value.";
         }
          list path-element {
            key "path-element-id";
            description
              "A list of path elements describing the service path";
         leaf path-element-id measure-interval {
           type uint32;
           default 30;
           description "To identify the element
             "Interval in a path.";
            }
            uses te-path-element;
          }
        } // underlay-primary-path
        list underlay-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, seconds to measure the list contains one or more
            elements."; extended metric
              values.";
         }
         leaf index advertisement-interval {
           type uint32;
           description
              "A sequence number
             "Interval in seconds to identify a backup path."; advertise the extended metric
              values.";
         }
         leaf provider-id-ref suppression-interval {
           type leafref uint32 {
              path "/tet:te-topologies/tet:topology/tet:provider-id";
              require-instance false;
             range "1 .. max";
           }
           default 120;
           description
              "A reference
             "Interval in seconds to a provider-id."; suppress advertising the extended
              metric values.";
         }
          leaf client-id-ref {
            type leafref
         container threshold-out {
              path "/tet:te-topologies/tet:topology/tet:client-id";
              require-instance false;
            }
           uses performance-metric-attributes;
           description
              "A reference to a client-id.";
             "If the measured parameter falls outside an upper bound
              for all but the min delay metric (or lower bound for
              min-delay metric only) and the advertised value is not
              already outside that bound, anomalous announcement will
              be triggered.";
         }
          leaf topology-id-ref {
            type leafref
         container threshold-in {
              path "/tet:te-topologies/tet:topology/tet:te-topology-id";
              require-instance false;
            }
           uses performance-metric-attributes;
           description
              "Identifies
             "If the topology where measured parameter falls inside an upper bound
              for all but the path belongs."; min delay metric (or lower bound for
              min-delay metric only) and the advertised value is not
              already inside that bound, normal (anomalous-flag
              cleared) announcement will be triggered.";
         }
          list path-element
         container threshold-accelerated-advertisement {
            key "path-element-id";
           description
              "A list of path elements describing
             "When the backup service
               path";
            leaf path-element-id {
              type uint32;
              description "To identify difference between the element in a path.";
            } last advertised value and
              current measured value exceed this threshold, anomalous
              announcement will be triggered.";
           uses te-path-element; performance-metric-attributes;
         }
       }
     } // underlay-backup-path
        leaf underlay-protection-type performance-metric-throttle-container

     grouping te-link-augment {
          type uint16;
       description
            "Underlay protection type desired
         "Augmentatin for this link";
        } TE link.";

       container underlay-trail-src te {
          uses tet:link-end-ref;
         presence "TE support.";
         description
            "Source
           "Indicates TE link of the underlay trail.";
        } support.";

         container underlay-trail-des config {
          uses tet:link-end-ref;
           description
            "Destination TE link of the underlay trail.";
        }
             "Configuration data.";
           uses te-link-config;
         } // te-link-underlay-attributes

      grouping te-link-state-underlay-attributes {
        description "State attributes for te-link underlay.";
        leaf dynamic config
         container state {
          type boolean;
           config false;
           description
            "true if the underlay is dynamically created.";
             "Operational state data.";
           uses te-link-config;
           uses te-link-state-derived;
         }
        leaf committed {
          type boolean;
          description
            "true if the underlay is committed."; // state
       } // te
     } // te-link-state-underlay-attributes te-link-augment

     grouping performance-metric-attributes te-link-config {
       description
          "Link performance information in real time.";
        reference
          "draft-ietf-ospf-te-metric-extensions.";
        leaf unidirectional-delay {
          type uint32
         "TE link configuration grouping.";
       choice bundle-stack-level {
            range 0..16777215;
          }
         description "Delay
           "The TE link can be partitioned into bundled
            links, or latency component links.";
         case bundle {
           container bundled-links {
             description
               "A set of bundled links.";
             reference
               "RFC4201: Link Bundling in micro seconds.";
        } MPLS Traffic Engineering
               (TE).";
             list bundled-link {
               key "sequence";
               description
                 "Specify a bundled interface that is
                  further partitioned.";
               leaf unidirectional-min-delay sequence {
                 type uint32 {
            range 0..16777215;
          } uint32;
                 description "Minimum delay or latency
                   "Identify the sequence in micro seconds."; the bundle.";
               }
               leaf unidirectional-max-delay src-tp-ref {
                 type uint32 leafref {
            range 0..16777215;
                   path "../../../../../../nw:node[nw:node-id = "
                     + "current()/../../../../../nt:source/"
                     + "nt:source-node]/"
                     + "nt:termination-point/nt:tp-id";
                   require-instance true;
                 }
                 description "Maximum delay or latency in micro seconds.";
                   "Reference to another TE termination point on the
                    same souruce node.";
               }
               leaf unidirectional-delay-variation des-tp-ref {
                 type uint32 leafref {
            range 0..16777215;
                   path "../../../../../../nw:node[nw:node-id = "
                     + "current()/../../../../../nt:destination/"
                     + "nt:dest-node]/"
                     + "nt:termination-point/nt:tp-id";
                   require-instance true;
                 }
                 description "Delay variation in micro seconds.";
                   "Reference to another TE termination point on the
                    same destination node.";
               }
        leaf unidirectional-packet-loss
             } // list bundled-link
           }
         }
         case component {
          type decimal64
           container component-links {
            fraction-digits 6;
            range "0 .. 50.331642";
          }
             description
            "Packet loss as a percentage
               "A set of the total traffic sent
            over component links";
             list component-link {
               key "sequence";
               description
                 "Specify a configurable interval. The finest precision component interface that is
            0.000003%.";
        }
                  sufficient to unambiguously identify the
                  appropriate resources";

               leaf unidirectional-residual-bandwidth sequence {
                 type decimal64 {
            fraction-digits 2;
          } uint32;
                 description
            "Residual bandwidth that subtracts tunnel
            reservations from Maximum Bandwidth (or link capacity)
            [RFC3630] and provides an aggregated remainder across QoS
            classes.";
                   "Identify the sequence in the bundle.";
               }
               leaf unidirectional-available-bandwidth src-interface-ref {
                 type decimal64 {
            fraction-digits 2;
          } string;
                 description
            "Available bandwidth that is defined
                   "Reference to be residual
            bandwidth minus component link interface on the measured bandwidth used for the
            actual forwarding of non-RSVP-TE LSP packets.  For a
            bundled link, available bandwidth is defined
                    source node.";
               }
               leaf des-interface-ref {
                 type string;
                 description
                   "Reference to be the
            sum of the component link available bandwidths."; interface on the
                    destinatioin node.";
               }
        leaf unidirectional-utilized-bandwidth
             }
           }
         }
       } // bundle-stack-level

       leaf-list te-link-template {
         if-feature template;
         type decimal64 leafref {
            fraction-digits 2;
           path "../../../../te/templates/link-template/name";
         }
         description
            "Bandwidth utilization that represents the actual
            utilization of the link (i.e. as measured in the router).
            For a bundled link, bandwidth utilization is defined
           "The reference to
            be the sum of the component a TE link bandwidth
            utilizations."; template.";
       }
       uses te-link-config-attributes;
     } // performance-metric-attributes te-link-config

     grouping performance-metric-normality-attributes te-link-config-attributes {
       description
         "Link performance metric normality attributes.";
        reference
          "draft-ietf-ospf-te-metric-extensions.";
        leaf unidirectional-delay configuration attributes in a TE topology.";
       container te-link-attributes {
          type performance-metric-normality;
         description "Delay normality.";
        } "Link attributes in a TE topology.";
         uses sch:schedules;
         leaf unidirectional-min-delay access-type {
           type performance-metric-normality; te-link-access-type;
           description "Minimum delay
             "Link access type, which can be point-to-point or latency normality.";
              multi-access.";
         }
        leaf unidirectional-max-delay
         leaf-list flag {
           type performance-metric-normality; te-link-flag;
           description "Maximum delay or latency normality."; "Link flags.";
         }
         leaf unidirectional-delay-variation is-abstract {
           type performance-metric-normality; empty;
           description "Delay variation normality."; "Present if the link is abstract.";
         }
         leaf unidirectional-packet-loss name {
           type performance-metric-normality; string;
           description "Packet loss normality."; "Link Name.";
         }
        leaf unidirectional-residual-bandwidth
         container underlay {
          type performance-metric-normality;
           if-feature te-topology-hierarchy;
           presence
             "Indicates the underlay exists for this link.";
           description "Residual bandwidth normality."; "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 unidirectional-available-bandwidth admin-status {
           type performance-metric-normality; te-admin-status;
           description "Available bandwidth normality.";
             "The administrative state of the link.";
         }
        leaf unidirectional-utilized-bandwidth {
          type performance-metric-normality;
          description "Bandwidth utilization normality.";

         uses performance-metric-throttle-container;
         uses te-link-info-attributes;
       }
     } // performance-metric-normality-attributes te-link-config-attributes

     grouping performance-metric-throttle-container te-link-info-attributes {
       description
          "A container controlling performance metric throttle.";
        container performance-metric-throttle {
          if-feature te-performance-metric;
          must "suppression-interval >= measure-interval" {
            error-message
              "suppression-interval cannot be less then
                measure-interval";
            description
              "Constraint on suppression-interval and
                measure-interval.";
          }
          description
            "Link performance information in real time.";
          reference
            "draft-ietf-ospf-te-metric-extensions.";
          leaf unidirectional-delay-offset {
            type uint32 {
              range 0..16777215;
            }
            description
              "Offset value to be added to the measured delay value.";
          }
          leaf measure-interval {
            type uint32;
            default 30;
            description
              "Interval in seconds to measure the extended metric
              values.";
          }
          leaf advertisement-interval {
            type uint32;
            description
              "Interval in seconds to advertise the extended metric
              values.";
          }
          leaf suppression-interval {
            type uint32 {
              range "1 .. max";
            }
            default 120;
            description
              "Interval in seconds to suppress advertising the extended
              metric values.";
          }
          container threshold-out {
            uses performance-metric-attributes;
            description
              "If the measured parameter falls outside an upper bound
              for all but the min delay metric (or lower bound for
              min-delay metric only) and the advertised value is not
              already outside that bound, anomalous announcement will be
              triggered.";
          }
          container threshold-in {
            uses performance-metric-attributes;
            description
              "If the measured parameter falls inside an upper bound
              for all but the min delay metric (or lower bound for
              min-delay metric only) and the advertised value is not
              already inside that bound, normal (anomalous-flag cleared)
              announcement will be triggered.";
          }
          container threshold-accelerated-advertisement {
            description
              "When the difference between the last advertised value and
              current measured value exceed this threshold, anomalous
              announcement will be triggered.";
            uses performance-metric-attributes;
          }
        }
      } // performance-metric-throttle-container

      grouping te-link-info-attributes {
        description
          "Advertised TE information attributes.";
        leaf link-index
         "Advertised TE information attributes.";
       leaf link-index {
         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).";
       }
       leaf max-link-bandwidth {
         type decimal64 {
           fraction-digits 2;
         }
         description
           "Maximum bandwidth that can be seen on this link in this
            direction. Units in bytes per second"; second.";
         reference
           "RFC3630: Traffic Engineering (TE) Extensions to OSPF
            Version 2.
            RFC5305: IS-IS Extensions for Traffic Engineering.";
       }
       leaf max-resv-link-bandwidth {
         type decimal64 {
           fraction-digits 2;
         }
         description
           "Maximum amount of bandwidth that can be reserved in this
            direction in this link. Units in bytes per second"; 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";
          leaf priority 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"; "Priority.";
         }
         leaf bandwidth {
           type decimal64 {
             fraction-digits 2;
           }
           description
             "Unreserved bandwidth for this level"; level.";
         }
       }
       leaf te-default-metric {
         type uint32;
         description
           "Traffic Engineering Metric"; Metric.";
       }
       container performance-metric {
         if-feature te-performance-metric;
         description
           "Link performance information in real time.";
         reference
            "draft-ietf-ospf-te-metric-extensions.";
           "RFC7471: OSPF Traffic Engineering (TE) Metric Extensions.";
         container measurement {
           description
             "Measured performance metric values. Static configuration
              and manual overrides of these measurements are also
              allowed.";
           uses performance-metric-attributes;
         }
         container normality
         {
           description
             "Performance metric normality values.";
           uses performance-metric-normality-attributes;
         }
       }
       leaf link-protection-type {
         type enumeration {
           enum "unprotected" {
             description "unprotected"; "Unprotected.";
           }
           enum "extra-traffic" {
             description "Extra traffic"; traffic.";
           }
           enum "shared" {
             description "Shared"; "Shared.";
           }
           enum "1-for-1" {
             description "One for one protection"; protection.";
           }
           enum "1-plus-1" {
             description "One plus one protection"; protection.";
           }
           enum "enhanced" {
             description "Enhanced protection"; protection.";
           }
         }
         description
           "Link Protection Type desired for this link"; link.";
         reference
           "RFC4202: Routing Extensions in Support of
            Generalized Multi-Protocol Label Switching (GMPLS).";
       }
       list interface-switching-capabilities interface-switching-capability {
         key "switching-capability";
         description
           "List of interface capabilities Interface Switching Capabilities Descriptors (ISCD)
            for this interface"; 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"; interface.";
         }
         leaf encoding {
           type identityref {
             base te-types:lsp-encoding-types;
           }
           description
             "Encoding supported by this interface"; interface.";
         }
         list max-lsp-bandwidth {
           key "priority";
           max-elements "8";
           description
             "Maximum LSP Bandwidth at priorities 0-7"; 0-7.";
           leaf priority {
             type uint8 {
               range "0..7";
             }
             description "Priority"; "Priority.";
           }
           leaf bandwidth {
             type decimal64 {
               fraction-digits 2;
             }
             description
               "Max LSP Bandwidth for this level";
           }
         }
         container packet-switch-capable {
           when "../switching-capability = 'PSC-1'  or "
             +"../switching-capability = 'PSC-2' or "
             +"../switching-capability = 'PSC-3' or "
             +"../switching-capability = 'PSC-4'" {
             description "Valid only for PSC";
           }
           description
             "Interface has packet-switching capabilities"; capabilities.";
           leaf minimum-lsp-bandwidth {
             type decimal64 {
               fraction-digits 2;
             }
             description
               "Minimum LSP Bandwidth. Units in bytes per second";
           }
           leaf interface-mtu {
             type uint16;
             description
               "Interface MTU"; MTU.";
           }
         }
         container time-division-multiplex-capable {
           when "../switching-capability = 'TDM'" {
             description "Valid only for TDM";
           }
           description
             "Interface has time-division multiplex capabilities"; capabilities.";

           leaf minimum-lsp-bandwidth {
             type decimal64 {
               fraction-digits 2;
             }
             description
               "Minimum LSP Bandwidth. Units in bytes per second"; second.";
           }
           leaf indication {
             type enumeration {
               enum "standard" {
                 description
                   "Indicates support of standard SONET/SDH"; SONET/SDH.";
               }
               enum "arbitrary" {
                 description
                   "Indicates support of arbitrary
                               SONET/SDH"; SONET/SDH.";
               }
             }
             description
               "Indication whether the interface supports Standard or
                Arbitrary SONET/SDH";
           }
         }
         list interface-adjustment-capability {
           key "upper-sc";
           description
             "List of Interface Adjustment Capability Descriptors
              (IACD)for this link.";
           reference
             "RFC6001: Generalized MPLS (GMPLS) Protocol Extensions
              for Multi-Layer and Multi-Region Networks (MLN/MRN).";
           leaf upper-sc {
             type identityref {
               base te-types:switching-capabilities;
             }
             description
               "Switching Capability for this interface.";
           }
           leaf upper-encoding {
             type identityref {
               base te-types:lsp-encoding-types;
             }
             description
               "Encoding supported by this interface.";
           }
           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.";
             }
             leaf bandwidth {
               type decimal64 {
                 fraction-digits 2;
               }
               description
                 "Max LSP Bandwidth for this level.";
             }
           }
         } // interface-adjustment-capability
       } // interface-switching-capability
       container te-srlgs {
         description
           "A list of SLRGs.";
         leaf-list values {
           type te-types:srlg;
           description "SRLG value"; value.";
           reference
             "RFC4202: Routing Extensions in Support of
              Generalized Multi-Protocol Label Switching (GMPLS).";
         }
       }
     } // te-link-info-attributes

     grouping te-link-attributes te-link-state-derived {
       description
         "Link state attributes in a TE topology.";
        container te-link-attributes
       leaf oper-status {
         type te-oper-status;
         description "Link attributes in a TE topology.";
           "The current operational state of the link.";
       }
       uses config-schedule-attributes;
          leaf name information-source-attributes;
       list alt-information-sources {
            type string;
         key "information-source";
         description "Link Name";
           "A list of information sources learned but not used.";
         uses information-source-attributes;
         uses te-link-info-attributes;
       }
          leaf-list flag
       container recovery {
         description
           "Status of the recovery process.";
         leaf restoration-status {
           type flag-type; te-recovery-status;
           description "Link flags";
             "Restoration status.";
         }
         leaf is-abstract protection-status {
           type boolean; te-recovery-status;
           description "true if the link is abstract.";
             "Protection status.";
         }
       }
       container underlay {
         if-feature te-topology-hierarchy;
            presence
              "Indicates the underlay exists for this link.";
         description "State of the underlay of this link."; attributes for te-link underlay.";
         uses te-link-underlay-attributes; te-link-state-underlay-attributes;
       }
     } // underlay te-link-state-derived

     grouping te-link-state-underlay-attributes {
       description "State attributes for te-link underlay.";
       leaf admin-status dynamic {
         type enumeration {
              enum up {
                value 1; boolean;
         description
                "Enabled.";
           "true if the underlay is dynamically created.";
       }
              enum down
       leaf committed {
                value 2;
         type boolean;
         description
                "Disabled.";
              }
              enum testing {
                value 3;
                description
                "In some test mode.";
              }
            }
            description
              "The desired state of
           "true if the link.";
          }

          uses performance-metric-throttle-container;
          uses te-link-info-attributes; underlay is committed.";
       }
     } // te-link-attributes te-link-state-underlay-attributes

     grouping te-link-state-attributes te-link-underlay-attributes {
       description
          "Link state attributes in a TE topology."; "Attributes for  te-link underlay.";
       reference
         "RFC4206: Label Switched Paths (LSP) Hierarchy with
          Generalized Multi-Protocol Label Switching (GMPLS)
          Traffic Engineering (TE)";
       container te-link-state underlay-primary-path {
         description "Link state attributes in a TE topology.";
           "The service path on the underlay topology that
            supports this link.";
         uses te-topology-ref;
         list path-element {
           key "path-element-id";
           description
             "A list of path elements describing the service path.";
           leaf oper-status path-element-id {
             type enumeration {
              enum up {
                value 1; uint32;
             description
                "Operational up"; "To identify the element in a path.";
           }
              enum down {
                value 2;
                description
                "Operational down.";
           uses te-path-element;
         }
              enum testing {
                value 3;
                description
                "In some test mode";
       }
              enum unknown // underlay-primary-path
       list underlay-backup-path {
                value 4;
                description
                "Status cannot be determined for some reason.";
              }
            }
         key "index";
         description
              "The current operational state
           "A list of backup service paths on the link."; 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 information-source-attributes; te-topology-ref;
         list alt-information-sources path-element {
           key "information-source"; "path-element-id";
           description
             "A list of information sources learned but not used.";
            uses information-source-attributes;
            uses te-link-info-attributes; 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;
         }

       } // te-link-state-attributes

      grouping template-attributes {
        description
          "Common attributes for all templates."; underlay-backup-path
       leaf priority underlay-protection-type {
         type uint16;
         description
            "The preference value to resolve conflicts between different
            templates. When two or more templates specify values
           "Underlay protection type desired for
            one configuration attribute, the value from this link";
       }
       container underlay-trail-src {
         uses tet:tp-ref;
         description
           "Source TE link of the template
            with underlay trail.";
       }
       container underlay-trail-des {
         uses tet:tp-ref;
         description
           "Destination TE link of the highest priority is used."; underlay trail.";
       }
        leaf reference-change-policy
     } // te-link-underlay-attributes

     grouping te-node-augment {
          type enumeration
       description
         "Augmentatin for TE node.";

       container te {
            enum no-action
         presence "TE support.";
         description
           "Indicates TE support.";

         leaf te-node-id {
           type te-node-id;
           mandatory true;
           description
                "When an attribute changes
             "The identifier of a node in this template, the
                configuration TE topology.
              A node referring is specific to this template does
                not take any action."; a topology to which it belongs.";
         }
            enum not-allowed

         container config {
           description
                "When any configuration object has a reference to this
                template, changing this template is not allowed.";
             "Configuration data.";
           uses te-node-config;
         }
            enum cascade // config
         container state {
           config false;
           description
                "When an attribute changes in this template, the
                configuration object referring to this template applies
                the new attribute value to the corresponding
                configuration.";
             "Operational state data.";

           uses te-node-config;
           uses te-node-state-derived;
         } // state
       } // te
     } // te-node-augment

     grouping te-node-config {
       description
            "This attribute specifies the action taken to a
    configuration "TE node that has a configuration grouping.";

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

      /*
       * Configuration data nodes
       */

      container te-topologies te-node-config

     grouping te-node-config-attributes {
       description
          "This "Configuration node attributes in a TE topology.";
       container acts as the top-level data element te-node-attributes {
         description "Containing node attributes in a TE topology.";
         uses sch:schedules;
         leaf admin-status {
           type te-admin-status;
           description
             "The administrative state of
           configuration data."; the link.";
         }
         list topology connectivity-matrix {
           key "provider-id client-id te-topology-id"; "id";
           description
            "This is the model of an abstract topology. A topology
            contains nodes and links. Each topology MUST be identified
            by a unique te-topology-id for reason that a
             "Represents node's switching limitations, i.e. limitations
              in interconnecting network could
            contain many topologies."; TE links across the node.";
           leaf provider-id id {
             type te-global-id; uint32;
             description
              "An identifier "Identifies the connectivity-matrix entry.";
           }
           container from {
             uses tet:tp-ref;
             description
               "Reference to uniquely identify a provider."; source NTP.";
           }
          leaf client-id
           container to {
            type te-global-id;
             uses tet:tp-ref;
             description
              "An identifier
               "Reference to uniquely identify a client."; destination NTP.";
           }
           leaf te-topology-id is-allowed {
             type te-topology-id; boolean;
             description
              "It
               "true  - switching is presumed that a datastore will contain many
              topologies. To distinguish between topologies it allowed,
                false - switching is
              vital to have UNIQUE topology identifiers."; disallowed.";
           }
          uses config-schedule-attributes;
          container topology-types
         }
         leaf domain-id {
           type uint32;
           description
              "This container is used to identify the type, or types (as
              a topology can support several types simultaneously), of
              the topology.
              Topology types are
             "Identifies the subject of several integrity
              constraints domain that an implementing server can validate in
              order to maintain integrity of the datastore.
              Topology types are indicated through separate data nodes;
              the set of topology types this node belongs.
              This attribute is expected used to increase over
              time.
              To add support inter-domain links.";
           reference
             "RFC5152: A Per-Domain Path Computation Method for a new topology, an augmenting module
              needs to augment this container with a new empty optional
              container to indicate the new topology type.
              The use of a container allows to indicate a
              subcategorization
              Establishing Inter-Domain Traffic Engineering (TE)
              Label Switched Paths (LSPs).
              RFC5392: OSPF Extensions in Support of topology types.
              The container SHALL NOT be augmented with any data nodes
              that serve a purpose other than identifying a particular
              topology type.";
            uses te-topology-type; // Defines the TE topology type. Inter-Autonomous
              System (AS) MPLS and GMPLS Traffic Engineering.
              RFC5316: ISIS Extensions in Support of Inter-Autonomous
              System (AS) MPLS and GMPLS Traffic Engineering.";
         }
          list node
         leaf-list flag {
            key "te-node-id";
           type te-node-flag;
           description "Node operational flags.";
         }
         leaf te-node-id is-abstract {
           type te-node-id; empty;
           description
                "The identifier of a node in
             "Present if the topology.
                A node is specific to 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 topology,
              the attributes in this container point to which it belongs."; said
   topology.";
           uses te-topology-ref;
         }
       }
     } // te-node-config-attributes

     grouping te-node-state-derived {
       description "Node state attributes in a TE topology.";
       leaf oper-status {
         type te-oper-status;
         description
           "The list current operational state of network nodes defined for the topology."; node.";
       }
       leaf te-node-template is-multi-access-dr {
              if-feature template;
         type leafref {
                path "/te-topologies/node-template/name";
              } empty;
         description
           "The presence of this attribute indicates that this TE node
            is a pseudonode elected as a designated router.";
         reference
           "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-attributes;
     } // te-node-state-derived

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

     grouping te-termination-point-augment {
            key "source-te-node-id source-te-link-id "
              + "dest-te-node-id dest-te-link-id";
       description
         "Augmentatin for TE termination point.";

       container te {
         presence "TE support.";
         description
           "Indicates TE support.";

         leaf source-te-node-id te-tp-id {
           type leafref {
                path "../../node/te-node-id";
              } te-tp-id;
           mandatory true;
           description
                "Source node identifier, must be in same topology.";
             "An identifier to uniquely identify a TE termination
              point.";
         }
            leaf source-te-link-id

         container config {
              type leafref
           description
             "Configuration data.";
           uses te-termination-point-config;
         } // config
         container state {
                path "../../node[te-node-id = "
                  + "current()/../source-te-node-id]/"
                  + "te-link/te-link-id";
           config false;
           description
             "Operational state data.";
           uses te-termination-point-config;
         }
              mandatory true; // state
       } // te
     } // te-termination-point-augment

     grouping te-termination-point-config {
       description
                "Source
         "TE termination point configuration grouping.";
       uses sch:schedules;
     } // te-termination-point-config

     grouping te-topology-augment {
       description
         "Augmentatin for TE link identifier, must be in same topology.";
            }

       container te {
         presence "TE support.";
         description
           "Indicates TE support.";

         leaf dest-te-node-id provider-id {
           type leafref {
                path "../../node/te-node-id";
              } te-global-id;
           mandatory true;
           description
                "Destination node identifier, must be in the same
                topology.";
             "An identifier to uniquely identify a provider.";
         }
         leaf dest-te-link-id client-id {
           type leafref {
                path "../../node[te-node-id = "
                  + "current()/../dest-te-node-id]/"
                  + "te-link/te-link-id";
              } te-global-id;
           mandatory true;
           description
                "Destination TE link identifier, must be in same
                topology.";
             "An identifier to uniquely identify a client.";

         }
         leaf te-topology-id {
           type te-topology-id;
           mandatory true;
           description
              "TE link
             "It is a logical construct that represents a way
              to group/map information about certain physical
              resources (and their properties) presumed that interconnect TE
              nodes.
              A Network Link connects a by Local (Source) node and
              a Remote (Destination) Network Nodes via a set of the
              nodes' TE links.
              As datastore will contain many
              topologies. To distinguish between topologies it is possible
              vital to have several links between the
              same source and destination nodes, and as a link
              could potentially be re-homed, to ensure that we
              would always know to distinguish between
              links, every link is identified by a dedicated link
              identifier.
              Note that a link models a point-to-point link, not a
              multipoint link.";
            leaf te-link-template {
              if-feature template;
              type leafref {
                path "/te-topologies/link-template/name"; UNIQUE topology identifiers.";
         }

         container config {
           description
                "The reference to a TE link template.";
            }
             "Configuration data.";
           uses te-link-attributes; te-topology-config;
         } // link config
         container state {
           config false;
           description
             "Operational state data.";
           uses te-topology-config;
         } // topology state

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

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

           list link-template {
             if-feature template;
             key "name";
             leaf name {
               type 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;
          leaf-list te-link-template
             uses te-link-config-attributes;
           } // link-template
         } // templates
       } // te
     } // te-topology-augment

     grouping te-topology-config {
       description
         "TE topology configuration grouping.";
       uses sch:schedules;
     } // te-topology-config

     grouping te-topology-ref {
       description
         "References a TE topology.";
       leaf provider-id-ref {
         type leafref {
           path "/te-topologies/link-template/name"; "/nw:network/tet:te/tet:provider-id";
           require-instance false;
         }
         description
              "The
           "A reference to a TE link template.";
          }
          uses te-link-attributes;
        } // link provider-id.";
       } // te-topologies

      /*
       * Operational state data nodes
       */

      container te-topologies-state
       leaf client-id-ref {
        config
         type leafref {
           path "/nw:network/tet:te/tet:client-id";
           require-instance false;
         }
         description
          "This container acts as the top-level state data element of
           operational data.";
        list topology {
          key "provider-id client-id te-topology-id";
          description
            "This is the model of an abstract topology. A topology
            contains nodes and links. Each topology MUST be identified
            by a unique te-topology-id for reason that
           "A reference to a network could
            contain many topologies."; client-id.";
       }
       leaf provider-id te-topology-id-ref {
         type te-global-id; leafref {
           path "/nw:network/tet:te/tet:te-topology-id";
           require-instance false;
         }
         description
              "An identifier
           "A reference to uniquely identify a provider."; te-topology-id.";

       }
       leaf client-id network-id-ref {
         type te-global-id; leafref {
           path "/nw:network/nw:network-id";
           require-instance false;
         }
         description
              "An identifier
           "A reference to uniquely identify a client."; network-id in base ietf-network module.";
       }
          leaf te-topology-id
     } // te-topology-ref

     grouping te-topology-type {
            type te-topology-id;
       description
              "It is presumed that a datastore will contain many
              topologies. To distinguish between topologies it is
              vital to have UNIQUE
         "Identifies the TE topology identifiers."; type.";
       container te-topology {
         presence "Indicates TE topology.";
         description
           "Its presence identifies the TE topology type.";
       }
     } // te-topology-type

     grouping template-attributes {
       description
         "Common attributes for all templates.";

       leaf server-provided priority {
         type boolean;
            config false; uint16;
         description
              "Indicates whether the topology is configurable by
              clients,
           "The preference value to resolve conflicts between different
            templates. When two or whether it is provided by more templates specify values for
            one configuration attribute, the server.  This leaf is
              populated by value from the server implementing template
            with the model.
              It is set to false for topologies that are created by a
              client; it is set to true otherwise.  If it highest priority is set to
    true,
              any attempt to edit the topology MUST be rejected."; used.";
       }
          container topology-types
       leaf reference-change-policy {
         type enumeration {
           enum no-action {
             description
              "This container is used to identify the type, or types (as
              a topology can support several types simultaneously), of
              the topology.
              Topology types are the subject of several integrity
              constraints that
               "When an implementing server can validate attribute changes in
              order to maintain integrity of this template, the datastore.
              Topology types are indicated through separate data nodes;
              the set of topology types is expected to increase over
              time.
              To add support for a new topology, an augmenting module
              needs
                configuration node referring to augment this container with a new empty optional
              container to indicate the new topology type.
              The use of a container allows to indicate a
              subcategorization of topology types.
              The container SHALL NOT be augmented with template does
                not take any data nodes
              that serve a purpose other than identifying a particular
              topology type.";
            uses te-topology-type; // Defines the TE topology type. action.";
           }
          list node {
            key "te-node-id";
            leaf te-node-id
           enum not-allowed {
              type te-node-id;
             description
                "The identifier of
               "When any configuration object has a node reference to this
                template, changing this template is not allowed.";
           }
           enum cascade {
             description
               "When an attribute changes in this template, the topology.
                A node is specific
                configuration object referring to a topology this template applies
                the new attribute value to which it belongs.";
            }
            description
              "The list of network nodes defined for the topology.";
            leaf te-node-template {
              if-feature template;
              type leafref {
                path "/te-topologies/node-template/name"; corresponding
                configuration.";
           }
         }
         description
                "The reference
           "This attribute specifies the action taken to a TE
            configuration node that has a reference to this template.";
       }
            uses te-node-attributes;
            uses te-node-state-attributes;
     }
          list link {
            key "source-te-node-id source-te-link-id "
              + "dest-te-node-id dest-te-link-id";
            leaf source-te-node-id {
              type leafref // template-attributes

     /*
      * Configuration data nodes
      */
     augment "/nw:network/nw:network-types" {
                path "../../node/te-node-id";
              }
              mandatory true;
       description
                "Source node identifier, must be in same topology.";
            }
            leaf source-te-link-id {
         "Introduce new network type leafref {
                path "../../node[te-node-id = "
                  + "current()/../source-te-node-id]/"
                  + "te-link/te-link-id";

              }
              mandatory true;
              description
                "Source for TE link identifier, must be in same topology.";
       uses te-topology-type;
     }
            leaf dest-te-node-id

     augment "/nw:network" {
              type leafref
       when "nw:network-types/te-topology" {
                path "../../node/te-node-id";
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
              mandatory true;
       description
                "Destination node identifier, must be in the same
         "Configuration parameters for TE topology.";
       uses te-topology-augment;
     }
            leaf dest-te-link-id

     augment "/nw:network/nw:node" {
              type leafref
       when "../nw:network-types/te-topology" {
                path "../../node[te-node-id = "
                  + "current()/../dest-te-node-id]/"
                  + "te-link/te-link-id";
              }
              mandatory true;
         description
                "Destination
           "Augmentation parameters apply only for networks with
            TE link identifier, must be in same
                topology."; topology type.";
       }
       description
              "TE link is a logical construct that represents a way
              to group/map information about certain physical
              resources (and their properties) that interconnect TE
              nodes.
              A Network Link connects a by Local (Source) node and
              a Remote (Destination) Network Nodes via a set of the
              nodes'
         "Configuration parameters for TE links.
              As it is possible to have several links between the
              same source and destination nodes, and as a link
              could potentially be re-homed, to ensure that we
              would always know to distinguish between
              links, every link is identified by a dedicated link
              identifier.
              Note that a link models a point-to-point link, not a
              multipoint link.";
            leaf te-link-template at node level.";
       uses te-node-augment;
     }

     augment "/nw:network/nt:link" {
              if-feature template;
              type leafref
       when "../nw:network-types/te-topology" {
                path "/te-topologies/link-template/name";
         description
           "Augmentation parameters apply only for networks with
            TE topology type.";
       }
       description
                "The reference to a
         "Configuration parameters for TE at link template.";
            }
            uses te-link-attributes; level";
       uses te-link-state-attributes; te-link-augment;
     } // link
        } // topology
      } // te-topologies

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

     /*
      * Operational state data nodes
      */

     /*
      * Notifications
      */

     notification te-node-event {
       description "Notification event for TE node"; node.";
       leaf event-type {
         type te-topology-event-type;
         description "Event type"; type.";
       }
       uses node-ref; tet:node-ref;
       uses te-topology-type;
       uses tet:te-node-attributes; tet:te-node-config-attributes;
       uses tet:te-node-state-attributes; tet:te-node-state-derived;
     }

     notification te-link-event {
       description "Notification event for TE link"; link.";
       leaf event-type {
         type te-topology-event-type;
         description "Event type";
       }
       uses link-ref; tet:link-ref;
       uses te-topology-type;
       uses tet:te-link-attributes; tet:te-link-config-attributes;
       uses tet:te-link-state-attributes; tet:te-link-state-derived;
     }

     augment "/te-link-event/te-link-attributes/underlay" {
       description "Add state attributes to te-link underlay.";
       uses te-link-state-underlay-attributes;
     }
   }

   <CODE ENDS>

7. 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.

8. 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.

   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

9. References

9.1. 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).

9.2. Informative References

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

10. 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.

Appendix A - Schedule Model

   A.1 Tree Structure

   module: ietf-schedule
   grouping schedules:
    +--rw schedules
       +--rw schedule* [schedule-id]
          +--rw schedule-id          uint32
          +--rw start?               yang:date-and-time
          +--rw schedule-duration?   string
          +--rw repeat-interval?     string

   A.2 YANG Module

   <CODE BEGINS>

   module ietf-schedule {
     yang-version 1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-schedule";
     // replace with IANA namespace when assigned

     prefix "sch";

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

     organization "TBD";
     contact "TBD";
     description
       "The model allows time scheduling parameters to be specified.";

     revision "2015-10-09" {
       description "Initial revision";
       reference "TBD";
     }

     /*
      * Groupings
      */

     grouping schedules {
       description
         "A list of schedules defining when a particular
          configuration takes effect.";
       container schedules {
         description
           "Container of a schedule list defining when a particular
            configuration takes effect.";
         list schedule {
           key "schedule-id";
           description "A list of schedule elements.";

           leaf schedule-id {
             type uint32;
             description "Identifies the schedule element.";

           }
           leaf start {
             type yang:date-and-time;
             description "Start time.";
           }
           leaf schedule-duration {
             type string {
               pattern
                 'P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?(\d+S)?';
             }
             description "Schedule duration in ISO 8601 format.";
           }
           leaf repeat-interval {
             type string {
               pattern
                 'R\d*/P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?'
                 + '(\d+S)?';
             }
             description "Repeat interval in ISO 8601 format.";
           }
         }
       }
     } // schedules
   }

   <CODE ENDS>

Contributors

   Sergio Belotti
   Alcatel Lucent
   Email: sergio.belotti@alcatel-lucent.com

   Dieter Beller
   Alcatel Lucent
   Email: dieter.beller@alcatel-lucent.com

Authors' Addresses

   Xufeng Liu
   Ericsson
   Email: xufeng.liu@ericsson.com

   Igor Bryskin
   ADVA Optical Networking
   Email: ibryskin@advaoptical.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