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 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, 2016                                   July 6, 2015
 
 
                      YANG Data Model for TE Topologies
                       draft-ietf-teas-yang-te-topo-01
 
 
 Status of this Memo
 
    This Internet-Draft is submitted in full conformance with the
    provisions of BCP 78 and BCP 79.
 
    Internet-Drafts are working documents of the Internet Engineering
    Task Force (IETF), its areas, and its working groups.  Note that
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    Drafts.
 
    Internet-Drafts are draft documents valid for a maximum of six
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    reference material or to cite them other than as "work in progress."
 
    The list of current Internet-Drafts can be accessed at
    http://www.ietf.org/ietf/1id-abstracts.txt
 
    The list of Internet-Draft Shadow Directories can be accessed at
    http://www.ietf.org/shadow.html
 
    This Internet-Draft will expire on January 6, 2016.
 
 Copyright Notice
 
    Copyright (c) 2015 IETF Trust and the persons identified as the
    document authors. All rights reserved.
 
 
 
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    This document is subject to BCP 78 and the IETF Trust's Legal
    Provisions Relating to IETF Documents
    (http://trustee.ietf.org/license-info) in effect on the date of
    publication of this document. Please review these documents
    carefully, as they describe your rights and restrictions with
    respect to this document.  Code Components extracted from this
    document must include Simplified BSD License text as described in
    Section 4.e of the Trust Legal Provisions and are provided without
    warranty as described in the Simplified BSD License.
 
 Abstract
 
    This document defines a YANG data model for representing, retrieving
    and manipulating TE Topologies. The model serves as a base model
    that other technology specific TE Topology models can augment.
 
 Conventions used in this document
 
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
    "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
    document are to be interpreted as described in RFC-2119 [RFC2119].
 
 
 Table of Contents
 
    1. Introduction...................................................3
       1.1. Terminology...............................................3
       1.2. Tree Structure - Legend...................................4
       1.3. Prefixes in Data Node Names...............................4
    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
       4.2. Model Structure..........................................10
       4.3. Topology Identifiers.....................................11
       4.4. Generic TE Link Attributes...............................12
       4.5. Generic TE Node Attributes...............................12
       4.6. TED Information Sources..................................13
       4.7. Overlay/Underlay Relationship............................14
       4.8. Scheduling Parameters....................................15
       4.9. Templates................................................15
       4.10. Notifications...........................................16
       4.11. Open Items..............................................17
    5. Tree Structure................................................17
 
 
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    6. TE Topology Yang Module.......................................42
    7. Security Considerations.......................................78
    8. IANA Considerations...........................................78
    9. References....................................................78
       9.1. Normative References.....................................78
       9.2. Informative References...................................79
    10. Acknowledgments..............................................79
 
 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.
 
 
 
 
 
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 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.
 
 
 
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                +--------+-----------------+-----------+
                | 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.
 
 
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    - 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
 
 
           ---------------
           | 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
 
 
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    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.
 
                                      :
    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
 
 
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    (Figure 2a). An implementation MAY choose to construct separate TE
    Topologies based on the information source. The native TE Topologies
    constructed using only nodes and links that were learnt via a
    specific information source are depicted in Figure 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 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
 
 
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    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
 
 
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    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.
 
    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 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 the generic model
 
 4.2. Model Structure
 
    The high-level model structure proposed by this document is as shown
    below:
 
       +--rw te-topologies
       |  +--rw topology* [provider-id client-id te-topology-id]
 
 
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       |  |  ..........
       |  |  +--rw node* [te-node-id]
       |  |  |  ..........
       |  |  |  +--rw te-link* [te-link-id]
       |  |  |     ..........
       |  |  +--rw link* [source-te-node-id source-te-link-id dest-te-
    node-id dest-te-link-id]
       |  |  |  ..........
       |  +--rw node-template* [name] {template}?
       |  |  ..........
       |  +--rw link-template* [name] {template}?
       |  |  ..........
       +--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]
             |  |  ..........
             |  +--ro te-link-state
             |     ..........
 
    notifications:
       +---n te-node-event
       |   ..........
       +---n te-link-event
           ..........
 
 4.3. 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.
 
       +--rw topology* [provider-id client-id te-topology-id]
       |  +--rw provider-id       te-global-id
       |  +--rw client-id         te-global-id
       |  +--rw te-topology-id    te-topology-id
 
 
 
 
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 4.4. 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 performance-metric-throttle {te-performance-metric}?
      |  |  ..........
      |  +--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* [switching-capability]
      |  |  ..........
      |  +--rw te-srlgs
      |  |  ..........
 
 4.5. 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
      |     |  +--rw topology-id-ref?   leafref
      |     |  +--rw node-ref?          leafref
      |     |  +--rw link-end-ref?      leafref
      |     +--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
 
 
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 4.6. 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.
 
       +--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
             |     +--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 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
             |      +--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
 
 
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             |         |  +--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
             |         |  ..........
 
 4.7. 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").
 
      +--rw node* [te-node-id]
      |  ..........
      |  +--rw te-node-attributes
      |  |  ..........
      |  |  +--rw underlay-topology {te-topology-hierarchy}?
      |  |  |  +--rw provider-id-ref?   leafref
      |  |  |  +--rw client-id-ref?     leafref
      |  |  |  +--rw topology-id-ref?   leafref
 
 
      +--rw link* [source-te-node-id source-te-link-id dest-te-node-id
    dest-te-link-id]
      |  ..........
      |  +--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?   leafref
      |  |  |  |  +--rw path-element* [path-element-id]
      |  |  |  |     ..........
      |  |  |  +--rw underlay-backup-path* [index]
      |  |  |  |  +--rw index              uint32
 
 
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      |  |  |  |  +--rw provider-id-ref?   leafref
      |  |  |  |  +--rw client-id-ref?     leafref
      |  |  |  |  +--rw topology-id-ref?   leafref
      |  |  |  |  +--rw path-element* [path-element-id]
      |  |  |  |     ..........
      |  |  |  +--rw underlay-protection-type?   uint16
      |  |  |  +--rw underlay-trail-src
      |  |  |     ..........
      |  |  |  +--rw underlay-trail-des
      |  |  |     ..........
 
 
 
 4.8. 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 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. 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}?
      |        ..........
 
 
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      |
      +--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. 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.
 
 
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    - 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. 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
       +--rw te-topologies
       |  +--rw topology* [provider-id client-id te-topology-id]
       |  |  +--rw provider-id       te-global-id
       |  |  +--rw client-id         te-global-id
       |  |  +--rw te-topology-id    te-topology-id
       |  |  +--rw schedules* [schedule-id] {configuration-schedule}?
       |  |  |  +--rw schedule-id          uint32
       |  |  |  +--rw start?               yang:date-and-time
       |  |  |  +--rw schedule-duration?   string
       |  |  |  +--rw repeat-interval?     string
       |  |  +--rw topology-types
       |  |  |  +--rw te-topology!
       |  |  +--rw node* [te-node-id]
       |  |  |  +--rw te-node-id            te-node-id
       |  |  |  +--rw te-node-template?     leafref {template}?
       |  |  |  +--rw te-node-attributes
       |  |  |  |  +--rw schedules* [schedule-id] {configuration-
    schedule}?
       |  |  |  |  |  +--rw schedule-id          uint32
       |  |  |  |  |  +--rw start?               yang:date-and-time
       |  |  |  |  |  +--rw schedule-duration?   string
       |  |  |  |  |  +--rw repeat-interval?     string
 
 
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       |  |  |  |  +--rw name?                  inet:domain-name
       |  |  |  |  +--rw signaling-address*     inet:ip-address
       |  |  |  |  +--rw flag*                  flag-type
       |  |  |  |  +--rw is-abstract?           boolean
       |  |  |  |  +--rw underlay-topology {te-topology-hierarchy}?
       |  |  |  |  |  +--rw provider-id-ref?   leafref
       |  |  |  |  |  +--rw client-id-ref?     leafref
       |  |  |  |  |  +--rw topology-id-ref?   leafref
       |  |  |  |  +--rw connectivity-matrix* [id]
       |  |  |  |     +--rw id            uint32
       |  |  |  |     +--rw from-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 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
       |  |     +--rw dest-te-link-id       leafref
       |  |     +--rw te-link-template?     leafref {template}?
       |  |     +--rw te-link-attributes
       |  |        +--rw schedules* [schedule-id] {configuration-
    schedule}?
 
 
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       |  |        |  +--rw schedule-id          uint32
       |  |        |  +--rw start?               yang:date-and-time
       |  |        |  +--rw schedule-duration?   string
       |  |        |  +--rw repeat-interval?     string
       |  |        +--rw name?                               string
       |  |        +--rw flag*                               flag-type
       |  |        +--rw is-abstract?                        boolean
       |  |        +--rw underlay! {te-topology-hierarchy}?
       |  |        |  +--rw underlay-primary-path
       |  |        |  |  +--rw provider-id-ref?   leafref
       |  |        |  |  +--rw client-id-ref?     leafref
       |  |        |  |  +--rw topology-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?   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
 
 
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       |  |        |  |        +--:(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?   leafref
       |  |        |  |  +--rw node-ref?          leafref
       |  |        |  |  +--rw link-end-ref?      leafref
       |  |        |  +--rw underlay-trail-des
       |  |        |     +--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 admin-status?                       enumeration
       |  |        +--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
 
 
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       |  |        |  |  +--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
 
 
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       |  |        +--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* [switching-
    capability]
       |  |        |  +--rw switching-capability
    identityref
 
 
 
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       |  |        |  +--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
       |  |           +--rw values*   te-types:srlg
       |  +--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 schedules* [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
       |  |  |  +--rw signaling-address*     inet:ip-address
       |  |  |  +--rw flag*                  flag-type
       |  |  |  +--rw is-abstract?           boolean
       |  |  |  +--rw underlay-topology {te-topology-hierarchy}?
       |  |  |  |  +--rw provider-id-ref?   leafref
       |  |  |  |  +--rw client-id-ref?     leafref
       |  |  |  |  +--rw topology-id-ref?   leafref
       |  |  |  +--rw connectivity-matrix* [id]
       |  |  |     +--rw id            uint32
       |  |  |     +--rw from-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 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
 
 
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       |  |  |     +--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-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
       |        +--rw schedules* [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
       |        +--rw flag*                               flag-type
       |        +--rw is-abstract?                        boolean
       |        +--rw underlay! {te-topology-hierarchy}?
       |        |  +--rw underlay-primary-path
       |        |  |  +--rw provider-id-ref?   leafref
       |        |  |  +--rw client-id-ref?     leafref
       |        |  |  +--rw topology-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
 
 
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       |        |  |        +--:(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?   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?   leafref
       |        |  |  +--rw node-ref?          leafref
       |        |  |  +--rw link-end-ref?      leafref
       |        |  +--rw underlay-trail-des
       |        |     +--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 admin-status?                       enumeration
 
 
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       |        +--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
 
 
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       |        +--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* [switching-
    capability]
       |        |  +--rw switching-capability               identityref
       |        |  +--rw encoding?                          identityref
       |        |  +--rw max-lsp-bandwidth* [priority]
       |        |  |  +--rw priority     uint8
 
 
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       |        |  |  +--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
       |           +--rw values*   te-types:srlg
       +--ro te-topologies-state
          +--ro topology* [provider-id client-id te-topology-id]
             +--ro provider-id        te-global-id
             +--ro client-id          te-global-id
             +--ro te-topology-id     te-topology-id
             +--ro server-provided?   boolean
             +--ro topology-types
             |  +--ro te-topology!
             +--ro node* [te-node-id]
             |  +--ro te-node-id            te-node-id
             |  +--ro te-node-template?     leafref {template}?
             |  +--ro te-node-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?                  inet:domain-name
             |  |  +--ro signaling-address*     inet:ip-address
             |  |  +--ro flag*                  flag-type
             |  |  +--ro is-abstract?           boolean
             |  |  +--ro underlay-topology {te-topology-hierarchy}?
             |  |  |  +--ro provider-id-ref?   leafref
             |  |  |  +--ro client-id-ref?     leafref
             |  |  |  +--ro topology-id-ref?   leafref
             |  |  +--ro connectivity-matrix* [id]
             |  |     +--ro id            uint32
             |  |     +--ro from-link
             |  |     |  +--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 to-link
             |  |     |  +--ro provider-id-ref?   leafref
             |  |     |  +--ro client-id-ref?     leafref
 
 
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             |  |     |  +--ro topology-id-ref?   leafref
             |  |     |  +--ro node-ref?          leafref
             |  |     |  +--ro link-end-ref?      leafref
             |  |     +--ro is-allowed?   boolean
             |  +--ro te-link* [te-link-id]
             |  |  +--ro te-link-id         te-link-id
             |  |  +--ro (stack-level)?
             |  |     +--:(bundle)
             |  |     |  +--ro bundled-links
             |  |     |     +--ro bundled-link* [sequence]
             |  |     |        +--ro sequence       uint32
             |  |     |        +--ro te-link-ref?   leafref
             |  |     +--:(component)
             |  |        +--ro component-links
             |  |           +--ro component-link* [sequence]
             |  |              +--ro sequence              uint32
             |  |              +--ro component-link-ref?   leafref
             |  +--ro te-node-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 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
 
 
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                |  |  |  +--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
                |  |  |        |  +--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?   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
 
 
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                |  |  |        |  +--ro interface-id?       uint32
                |  |  |        +--:(label)
                |  |  |           +--ro value?              uint32
                |  |  +--ro underlay-protection-type?   uint16
                |  |  +--ro underlay-trail-src
                |  |  |  +--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 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
 
 
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                |  |  +--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
 
 
 
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                |  |  |  +--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]
                |  |  +--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
 
 
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                |  |  +--ro time-division-multiplex-capable
                |  |     +--ro minimum-lsp-bandwidth?   decimal64
                |  |     +--ro indication?              enumeration
                |  +--ro te-srlgs
                |     +--ro values*   te-types:srlg
                +--ro te-link-state
                   +--ro oper-status?                enumeration
                   +--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?     leafref
                      |  |  +--ro topology-id-ref?   leafref
                      |  +--ro routing-instance?         string
                      +--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
 
 
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                      |  |  +--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]
                      |  +--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
 
 
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 Internet-Draft            YANG - TE Topology                  July 2015
 
 
       |  +--ro event-type?           te-topology-event-type
       |  +--ro provider-id-ref?      leafref
       |  +--ro client-id-ref?        leafref
       |  +--ro topology-id-ref?      leafref
       |  +--ro node-ref?             leafref
       |  +--ro te-topology!
       |  +--ro te-node-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?                  inet:domain-name
       |  |  +--ro signaling-address*     inet:ip-address
       |  |  +--ro flag*                  flag-type
       |  |  +--ro is-abstract?           boolean
       |  |  +--ro underlay-topology {te-topology-hierarchy}?
       |  |  |  +--ro provider-id-ref?   leafref
       |  |  |  +--ro client-id-ref?     leafref
       |  |  |  +--ro topology-id-ref?   leafref
       |  |  +--ro connectivity-matrix* [id]
       |  |     +--ro id            uint32
       |  |     +--ro from-link
       |  |     |  +--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 to-link
       |  |     |  +--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 is-allowed?   boolean
       |  +--ro te-link* [te-link-id]
       |  |  +--ro te-link-id         te-link-id
       |  |  +--ro (stack-level)?
       |  |     +--:(bundle)
       |  |     |  +--ro bundled-links
       |  |     |     +--ro bundled-link* [sequence]
       |  |     |        +--ro sequence       uint32
       |  |     |        +--ro te-link-ref?   leafref
       |  |     +--:(component)
       |  |        +--ro component-links
       |  |           +--ro component-link* [sequence]
 
 
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       |  |              +--ro sequence              uint32
       |  |              +--ro component-link-ref?   leafref
       |  +--ro te-node-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
       +---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?     leafref
          +--ro dest-te-link-id-ref?     leafref
          +--ro te-topology!
          +--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
          |  |  |        |  +--ro v4-loose?           boolean
          |  |  |        +--:(ipv6-address)
          |  |  |        |  +--ro v6-address?         inet:ipv6-address
          |  |  |        |  +--ro v6-prefix-length?   uint8
          |  |  |        |  +--ro v6-loose?           boolean
 
 
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          |  |  |        +--:(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?   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?   leafref
          |  |  |  +--ro client-id-ref?     leafref
          |  |  |  +--ro topology-id-ref?   leafref
          |  |  |  +--ro node-ref?          leafref
          |  |  |  +--ro link-end-ref?      leafref
          |  |  +--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
 
 
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          |  +--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
 
 
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          |  |  |  +--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]
          |  |  +--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
          +--ro te-link-state
             +--ro oper-status?                enumeration
             +--ro information-source?         enumeration
             +--ro information-source-state
             |  +--ro credibility-preference?   uint16
             |  +--ro topology
             |  |  +--ro provider-id-ref?   leafref
             |  |  +--ro client-id-ref?     leafref
 
 
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             |  |  +--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?     leafref
                |  |  +--ro topology-id-ref?   leafref
                |  +--ro routing-instance?         string
                +--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
 
 
 
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                |     +--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]
                |  +--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
 
 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 {
        prefix "if";
      }
 
 
 
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      import ietf-te-types {
        prefix "te-types";
      }
 
      organization "TBD";
      contact "TBD";
      description "TE topology model";
 
      revision "2015-07-02" {
        description "Initial revision";
        reference "TBD";
      }
 
      /*
       * Features
       */
 
      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.";
      }
 
      feature template {
        description
          "This feature indicates that the system supports
          template configuration.";
      }
 
      /*
       * Typedefs
       */
 
 
 
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      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 RFC503.
          This attribute type is used solely to provide a globally
          unique context for TE topologies.";
      }
 
      typedef te-topology-id {
        type string {
          pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
        }
        description
          "An identifier for a topology.";
      }
 
      typedef te-template-name {
        type string {
          pattern '/?([a-zA-Z0-9\-_.]+)(/[a-zA-Z0-9\-_.]+)*';
        }
        description
          "A type for the name of a TE node template or TE link
          template.";
      }
 
      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 is instantiated in
           separate
           datastores. An implementation MAY choose to capture semantics
           in the identifier, for example to indicate the type of node
           and/or the type of topology that the node is a part of.";
      }
 
      typedef te-link-id {
        type union {
          type uint32;          // Unnumbered
          type inet:ip-address; // IPv4 or IPv6 address
        }
 
 
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        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 be identified through the
           same identifier, even if the model is instantiated in
           separate
           datastores. An implementation MAY choose to capture semantics
           in the identifier, for example to indicate the type of TP
           and/or the type of node and topology that the TP is a part
           of.";
      }
 
      typedef te-topology-event-type {
        type enumeration {
          enum "add" {
            value 0;
            description
              "A TE node or te-link has
              been added";
          }
          enum "remove" {
            value 1;
            description
              "A TE node or te-link has
              been removed";
          }
          enum "update" {
            value 2;
            description
              "A TE node or te-link has
              been updated";
          }
        }
        description "TE  Event type for notifications";
      } // te-topology-event-type
 
      typedef performance-metric-normality {
        type enumeration {
          enum "unknown" {
            value 0;
            description
              "Unknown";
          }
          enum "normal" {
            value 1;
 
 
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            description
              "Normal";
          }
          enum "abnormal" {
            value 2;
            description
              "Abnormal. The anomalous bit is set.";
          }
        }
        description
          "Indicates whether a performance metric is normal, abnormal,
          or unknown.";
      }
 
      /*
       * Identities
       */
 
      identity flag-identity {
        description "Base type for flags";
      }
 
      identity undefined-flag {
        base "flag-identity";
        description "Undefined flag";
      }
 
      typedef flag-type {
        type identityref {
          base "flag-identity";
        }
        description "Type for flags";
      }
 
      /*
       * Groupings
       */
 
      grouping topo-ref {
        description
          "Grouping for an absolute reference to a topology instance.";
        leaf provider-id-ref {
          type leafref {
            path "/tet:te-topologies/tet:topology/tet:provider-id";
          }
 
 
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          description
            "An absolute reference to a provider-id.";
        }
        leaf client-id-ref {
          type leafref {
            path "/tet:te-topologies/tet:topology/tet:client-id";
          }
          description
            "An absolute reference to a client-id.";
        }
        leaf topology-id-ref {
          type leafref {
            path "/tet:te-topologies/tet:topology/tet:te-topology-id";
          }
          description
            "An absolute reference to a te-topology-id.";
        }
      } // topo-ref
 
      grouping link-ref {
        description
          "Grouping for an absolute reference to a link instance.";
        uses topo-ref;
        leaf source-te-node-id-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";
          }
          description
            "An absolute reference to a link instance.";
        }
        leaf source-te-link-id-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-link-id";
          }
          description
            "An absolute reference to a link instance.";
        }
        leaf dest-te-node-id-ref {
 
 
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          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-node-id";
          }
          description
            "An absolute reference to a link instance.";
        }
        leaf dest-te-link-id-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.";
        }
      } // link-ref
 
      grouping node-ref {
        description
          "Grouping for an absolute reference to a node instance.";
        uses topo-ref;
        leaf node-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";
          }
          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 {
 
 
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          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.";
 
 
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          }
          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";
            }
            enum "locally-configured" {
              description "Configured entity";
            }
            enum "ospfv2" {
              description "OSPFv2";
            }
            enum "ospfv3" {
              description "OSPFv3";
            }
            enum "isis" {
              description "ISIS";
            }
            enum "system-processed" {
              description "System processed entity.";
            }
            enum "other" {
              description "Other source";
            }
 
 
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          }
          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.";
            }
          } // topology
          leaf routing-instance {
 
 
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            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 {
        description "Node attributes in a TE topology.";
        container te-node-attributes {
          description "Node attributes in a TE topology.";
          uses config-schedule-attributes;
          leaf name {
            type inet:domain-name;
            description "Node name.";
          }
          leaf-list signaling-address {
            type inet:ip-address;
            description "Node signaling address.";
          }
          leaf-list flag {
            type flag-type;
            description "Node operational flags.";
          }
          leaf is-abstract {
            type boolean;
            description
              "true if the node is abstract, false when the node is
              actual.";
          }
          container underlay-topology {
            if-feature te-topology-hierarchy;
            description
              "When an abstract node encapsulates a topology,
              the attributes in this container point to said topology.";
            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";
 
 
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              }
              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.";
            }
          }
 
          list connectivity-matrix {
            key "id";
            description
              "Represents node's switching limitations, i.e. limitations
               in interconnecting network TE links across the node.";
            leaf id {
              type uint32;
              description "Identifies the connectivity-matrix entry.";
            }
            container from-link {
              uses tet:link-end-ref;
              description
                "Reference to source NTP.";
            }
            container to-link {
              uses tet:link-end-ref;
              description
                "Reference to destination NTP.";
            }
            leaf is-allowed {
              type boolean;
              description
                "true  - switching is allowed,
                 false - switching is disallowed.";
            }
          }
        }
        list te-link {
          key "te-link-id";
          description
            "The local representation of a TE link, which
            interconnect TE nodes.";
 
 
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          leaf te-link-id {
            type te-link-id;
            description
              "TE link identifier.";
          }
          choice stack-level {
            description
              "The TE link can be partitioned into bundled
              links, or component links.";
            case bundle {
              container bundled-links {
                description
                  "A set of bundled links";
                list bundled-link {
                  key "sequence";
                  description
                    "Specify a bundled interface that is
                    further partitioned.";
                  leaf sequence {
                    type uint32;
                    description
                      "Identify the sequence in the bundle.";
                  }
                  leaf te-link-ref {
                    type leafref {
                      path "../../../te-link-id";
                      require-instance true;
                    }
                    description
                      "Reference to TE link on this node.";
                  }
                }
              }
            }
            case component {
              container component-links {
                description
                  "A set of component links";
                list component-link {
                  key "sequence";
                  description
                    "Specify a component interface that is
                    sufficient to unambiguously identify the
                    appropriate resources";
 
                  leaf sequence {
 
 
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                    type uint32;
                    description
                      "Identify the sequence in the bundle.";
                  }
                  leaf component-link-ref {
                    type leafref {
                      path "/if:interfaces/if:interface/if:name";
                      require-instance false;
                    }
                    description
                      "Reference to component link on this
                      node.";
                  }
                }
              }
            }
          }
        }
      } // te-node-attributes
 
      grouping te-node-state-attributes {
        description "Node state attributes in a TE topology.";
        container te-node-state {
          description "Node state attributes in a TE topology.";
          uses information-source-attributes;
        }
      } // te-node-state-attributes
 
      grouping te-link-underlay-attributes {
        description "Attributes for  te-link underlay.";
        container underlay-primary-path {
          description
            "The service path 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;
            }
            description
              "A reference to a provider-id.";
          }
          leaf client-id-ref {
            type leafref {
              path "/tet:te-topologies/tet:topology/tet:client-id";
              require-instance false;
 
 
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            }
            description
              "A reference 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.";
          }
          list path-element {
            key "path-element-id";
            description
              "A list of path elements describing the service path";
            leaf path-element-id {
              type uint32;
              description "To identify the element in a path.";
            }
            uses te-path-element;
          }
        } // 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, the list contains one or more
            elements.";
          leaf index {
            type uint32;
            description
              "A sequence number to identify a backup path.";
          }
          leaf provider-id-ref {
            type leafref {
              path "/tet:te-topologies/tet:topology/tet:provider-id";
              require-instance false;
            }
            description
              "A reference to a provider-id.";
          }
          leaf client-id-ref {
 
 
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            type leafref {
              path "/tet:te-topologies/tet:topology/tet:client-id";
              require-instance false;
            }
            description
              "A reference 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.";
          }
          list path-element {
            key "path-element-id";
            description
              "A list of path elements describing the backup service
               path";
            leaf path-element-id {
              type uint32;
              description "To identify the element in a path.";
            }
            uses te-path-element;
          }
        } // underlay-backup-path
        leaf underlay-protection-type {
          type uint16;
          description
            "Underlay protection type desired for this link";
        }
        container underlay-trail-src {
          uses tet:link-end-ref;
          description
            "Source TE link of the underlay trail.";
        }
        container underlay-trail-des {
          uses tet:link-end-ref;
          description
            "Destination TE link of the underlay trail.";
        }
      } // te-link-underlay-attributes
 
      grouping te-link-state-underlay-attributes {
        description "State attributes for te-link underlay.";
 
 
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        leaf dynamic {
          type boolean;
          description
            "true if the underlay is dynamically created.";
        }
        leaf committed {
          type boolean;
          description
            "true if the underlay is committed.";
        }
      } // te-link-state-underlay-attributes
 
      grouping performance-metric-attributes {
        description
          "Link performance information in real time.";
        reference
          "draft-ietf-ospf-te-metric-extensions.";
        leaf unidirectional-delay {
          type uint32 {
            range 0..16777215;
          }
          description "Delay or latency in micro seconds.";
        }
        leaf unidirectional-min-delay {
          type uint32 {
            range 0..16777215;
          }
          description "Minimum delay or latency in micro seconds.";
        }
        leaf unidirectional-max-delay {
          type uint32 {
            range 0..16777215;
          }
          description "Maximum delay or latency in micro seconds.";
        }
        leaf unidirectional-delay-variation {
          type uint32 {
            range 0..16777215;
          }
          description "Delay variation in micro seconds.";
        }
        leaf unidirectional-packet-loss {
          type decimal64 {
            fraction-digits 6;
            range "0 .. 50.331642";
          }
 
 
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          description
            "Packet loss as a percentage of the total traffic sent
            over a configurable interval. The finest precision is
            0.000003%.";
        }
        leaf unidirectional-residual-bandwidth {
          type decimal64 {
            fraction-digits 2;
          }
          description
            "Residual bandwidth that subtracts tunnel
            reservations from Maximum Bandwidth (or link capacity)
            [RFC3630] and provides an aggregated remainder across QoS
            classes.";
        }
        leaf unidirectional-available-bandwidth {
          type decimal64 {
            fraction-digits 2;
          }
          description
            "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
            bundled link, available bandwidth is defined to be the
            sum of the component link available bandwidths.";
        }
        leaf unidirectional-utilized-bandwidth {
          type decimal64 {
            fraction-digits 2;
          }
          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 to
            be the sum of the component link bandwidth
            utilizations.";
        }
      } // performance-metric-attributes
 
      grouping performance-metric-normality-attributes {
        description
          "Link performance metric normality attributes.";
        reference
          "draft-ietf-ospf-te-metric-extensions.";
        leaf unidirectional-delay {
          type performance-metric-normality;
 
 
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          description "Delay normality.";
        }
        leaf unidirectional-min-delay {
          type performance-metric-normality;
          description "Minimum delay or latency normality.";
        }
        leaf unidirectional-max-delay {
          type performance-metric-normality;
          description "Maximum delay or latency normality.";
        }
        leaf unidirectional-delay-variation {
          type performance-metric-normality;
          description "Delay variation normality.";
        }
        leaf unidirectional-packet-loss {
          type performance-metric-normality;
          description "Packet loss normality.";
        }
        leaf unidirectional-residual-bandwidth {
          type performance-metric-normality;
          description "Residual bandwidth normality.";
        }
        leaf unidirectional-available-bandwidth {
          type performance-metric-normality;
          description "Available bandwidth normality.";
        }
        leaf unidirectional-utilized-bandwidth {
          type performance-metric-normality;
          description "Bandwidth utilization normality.";
        }
      } // performance-metric-normality-attributes
 
      grouping performance-metric-throttle-container {
        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
 
 
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            "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
 
 
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              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 {
          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";
        }
        leaf max-resv-link-bandwidth {
          type decimal64 {
            fraction-digits 2;
          }
          description
 
 
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            "Maximum amount of bandwidth that can be reserved in this
             direction in this link. Units in bytes per second";
        }
        list unreserved-bandwidth {
          key "priority";
          max-elements "8";
          description
            "Unreserved bandwidth for 0-7 priority levels. Units in
            bytes per second";
          leaf priority {
            type uint8 {
              range "0..7";
            }
            description "Priority";
          }
          leaf bandwidth {
            type decimal64 {
              fraction-digits 2;
            }
            description
              "Unreserved bandwidth for this level";
          }
        }
        leaf te-default-metric {
          type uint32;
          description
            "Traffic Engineering Metric";
        }
        container performance-metric {
          if-feature te-performance-metric;
          description
            "Link performance information in real time.";
          reference
            "draft-ietf-ospf-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;
 
 
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          }
        }
        leaf link-protection-type {
          type enumeration {
            enum "unprotected" {
              description "unprotected";
            }
            enum "extra-traffic" {
              description "Extra traffic";
            }
            enum "shared" {
              description "Shared";
            }
            enum "1-for-1" {
              description "One for one protection";
            }
            enum "1-plus-1" {
              description "One plus one protection";
            }
            enum "enhanced" {
              description "Enhanced protection";
            }
          }
          description
            "Link Protection Type desired for this link";
        }
        list interface-switching-capabilities {
          key "switching-capability";
          description
            "List of interface capabilities for this interface";
          leaf switching-capability {
            type identityref {
              base te-types:switching-capabilities;
            }
            description
              "Switching Capability for this interface";
          }
          leaf encoding {
            type identityref {
              base te-types:lsp-encoding-types;
            }
            description
              "Encoding supported by this interface";
          }
          list max-lsp-bandwidth {
            key "priority";
 
 
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            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";
            }
          }
          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";
            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";
            }
          }
          container time-division-multiplex-capable {
            when "../switching-capability = 'TDM'" {
              description "Valid only for TDM";
            }
            description
              "Interface has time-division multiplex capabilities";
 
 
 
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            leaf minimum-lsp-bandwidth {
              type decimal64 {
                fraction-digits 2;
              }
              description
                "Minimum LSP Bandwidth. Units in bytes per second";
            }
            leaf indication {
              type enumeration {
                enum "standard" {
                  description "Indicates support of standard SONET/SDH";
                }
                enum "arbitrary" {
                  description "Indicates support of arbitrary
                               SONET/SDH";
                }
              }
              description
                "Indication whether the interface supports Standard or
                 Arbitrary SONET/SDH";
            }
          }
        }
        container te-srlgs {
          description
            "A list of SLRGs.";
          leaf-list values {
            type te-types:srlg;
            description "SRLG value";
          }
        }
      } // te-link-info-attributes
 
      grouping te-link-attributes {
        description
          "Link attributes in a TE topology.";
        container te-link-attributes {
          description "Link attributes in a TE topology.";
          uses config-schedule-attributes;
          leaf name {
            type string;
            description "Link Name";
          }
          leaf-list flag {
            type flag-type;
            description "Link flags";
 
 
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          }
          leaf is-abstract {
            type boolean;
            description "true if the link is abstract.";
          }
          container underlay {
            if-feature te-topology-hierarchy;
            presence
              "Indicates the underlay exists for this link.";
            description "State of the underlay of this link.";
 
            uses te-link-underlay-attributes;
          } // underlay
          leaf admin-status {
            type enumeration {
              enum up {
                value 1;
                description
                "Enabled.";
              }
              enum down {
                value 2;
                description
                "Disabled.";
              }
              enum testing {
                value 3;
                description
                "In some test mode.";
              }
            }
            description
              "The desired state of the link.";
          }
 
          uses performance-metric-throttle-container;
          uses te-link-info-attributes;
        }
      } // te-link-attributes
 
      grouping te-link-state-attributes {
        description
          "Link state attributes in a TE topology.";
        container te-link-state {
          description "Link state attributes in a TE topology.";
          leaf oper-status {
 
 
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            type enumeration {
              enum up {
                value 1;
                description
                "Operational up";
              }
              enum down {
                value 2;
                description
                "Operational down.";
              }
              enum testing {
                value 3;
                description
                "In some test mode";
              }
              enum unknown {
                value 4;
                description
                "Status cannot be determined for some reason.";
              }
            }
            description
              "The current operational state of the link.";
          }
          uses information-source-attributes;
          list alt-information-sources {
            key "information-source";
            description
              "A list of information sources learned but not used.";
            uses information-source-attributes;
            uses te-link-info-attributes;
          }
        }
      } // te-link-state-attributes
 
      grouping template-attributes {
        description
          "Common attributes for all templates.";
 
        leaf priority {
          type uint16;
          description
            "The preference value to resolve conflicts between different
            templates. When two or more templates specify values for
            one configuration attribute, the value from the template
 
 
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            with the highest priority is used.";
        }
        leaf reference-change-policy {
          type enumeration {
            enum no-action {
              description
                "When an attribute changes in this template, the
                configuration node referring to this template does
                not take any action.";
            }
            enum not-allowed {
              description
                "When any configuration object has a reference to this
                template, changing this template is not allowed.";
            }
            enum cascade {
              description
                "When an attribute changes in this template, the
                configuration object referring to this template applies
                the new attribute value to the corresponding
                configuration.";
            }
          }
          description
            "This attribute specifies the action taken to a
    configuration
            node that has a reference to this template.";
        }
      } // template-attributes
 
      /*
       * Configuration data nodes
       */
 
      container te-topologies {
        description
          "This container acts as the top-level data element of
           configuration 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 network could
            contain many topologies.";
          leaf provider-id {
 
 
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            type te-global-id;
            description
              "An identifier to uniquely identify a provider.";
          }
          leaf client-id {
            type te-global-id;
            description
              "An identifier to uniquely identify a client.";
          }
          leaf te-topology-id {
            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 topology identifiers.";
          }
          uses config-schedule-attributes;
          container topology-types {
            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 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 is expected to increase over
              time.
              To add support 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 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.
          }
          list node {
            key "te-node-id";
            leaf te-node-id {
              type te-node-id;
              description
                "The identifier of a node in the topology.
                A node is specific to a topology to which it belongs.";
            }
 
 
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            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";
              }
              description
                "The reference to a TE node template.";
            }
            uses te-node-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 {
                path "../../node/te-node-id";
              }
              mandatory true;
              description
                "Source node identifier, must be in same topology.";
            }
            leaf source-te-link-id {
              type leafref {
                path "../../node[te-node-id = "
                  + "current()/../source-te-node-id]/"
                  + "te-link/te-link-id";
              }
              mandatory true;
              description
                "Source TE link identifier, must be in same topology.";
            }
            leaf dest-te-node-id {
              type leafref {
                path "../../node/te-node-id";
              }
              mandatory true;
              description
                "Destination node identifier, must be in the same
                topology.";
            }
            leaf dest-te-link-id {
              type leafref {
                path "../../node[te-node-id = "
                  + "current()/../dest-te-node-id]/"
 
 
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                  + "te-link/te-link-id";
              }
              mandatory true;
              description
                "Destination TE link identifier, must be in same
                topology.";
            }
            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' 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 {
              if-feature template;
              type leafref {
                path "/te-topologies/link-template/name";
              }
              description
                "The reference to a TE link template.";
            }
            uses te-link-attributes;
          } // link
        } // 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.";
 
 
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          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;
        } // node
 
        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 {
            type leafref {
              path "/te-topologies/link-template/name";
            }
            description
              "The reference to a TE link template.";
          }
          uses te-link-attributes;
        } // link
      } // te-topologies
 
      /*
       * Operational state data nodes
       */
 
      container te-topologies-state {
        config 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
 
 
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            "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 network could
            contain many topologies.";
          leaf provider-id {
            type te-global-id;
            description
              "An identifier to uniquely identify a provider.";
          }
          leaf client-id {
            type te-global-id;
            description
              "An identifier to uniquely identify a client.";
          }
          leaf te-topology-id {
            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 topology identifiers.";
          }
          leaf server-provided {
            type boolean;
            config false;
            description
              "Indicates whether the topology is configurable by
              clients,
              or whether it is provided by the server.  This leaf is
              populated by the server implementing the model.
              It is set to false for topologies that are created by a
              client; it is set to true otherwise.  If it is set to
    true,
              any attempt to edit the topology MUST be rejected.";
          }
          container topology-types {
            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 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 is expected to increase over
              time.
              To add support for a new topology, an augmenting module
 
 
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              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 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.
          }
          list node {
            key "te-node-id";
            leaf te-node-id {
              type te-node-id;
              description
                "The identifier of a node in the topology.
                A node is specific to a topology 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";
              }
              description
                "The reference to a TE node 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 {
                path "../../node/te-node-id";
              }
              mandatory true;
              description
                "Source node identifier, must be in same topology.";
            }
            leaf source-te-link-id {
              type leafref {
                path "../../node[te-node-id = "
                  + "current()/../source-te-node-id]/"
                  + "te-link/te-link-id";
 
 
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              }
              mandatory true;
              description
                "Source TE link identifier, must be in same topology.";
            }
            leaf dest-te-node-id {
              type leafref {
                path "../../node/te-node-id";
              }
              mandatory true;
              description
                "Destination node identifier, must be in the same
                topology.";
            }
            leaf dest-te-link-id {
              type leafref {
                path "../../node[te-node-id = "
                  + "current()/../dest-te-node-id]/"
                  + "te-link/te-link-id";
              }
              mandatory true;
              description
                "Destination TE link identifier, must be in same
                topology.";
            }
            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' 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 {
              if-feature template;
              type leafref {
                path "/te-topologies/link-template/name";
              }
 
 
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              description
                "The reference to a TE link template.";
            }
            uses te-link-attributes;
            uses te-link-state-attributes;
          } // link
        } // topology
      } // te-topologies
 
      augment "/te-topologies-state/topology/link/te-link-attributes/"
        + "underlay" {
        description "Add state attributes to te-link underlay.";
        uses te-link-state-underlay-attributes;
      }
 
      /*
       * Notifications
       */
 
      notification te-node-event {
        description "Notification event for TE node";
        leaf event-type {
          type te-topology-event-type;
          description "Event type";
        }
        uses node-ref;
        uses te-topology-type;
        uses tet:te-node-attributes;
        uses tet:te-node-state-attributes;
      }
 
      notification te-link-event {
        description "Notification event for TE link";
        leaf event-type {
          type te-topology-event-type;
          description "Event type";
        }
        uses link-ref;
        uses te-topology-type;
        uses tet:te-link-attributes;
        uses tet:te-link-state-attributes;
      }
 
      augment "/te-link-event/te-link-attributes/underlay" {
        description "Add state attributes to te-link underlay.";
        uses te-link-state-underlay-attributes;
 
 
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      }
    }
 
    <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.
 
 
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    [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.
 
 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
 
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