YANG Data Models for requesting Path Computation in Optical Networks
draft-gbb-ccamp-optical-path-computation-yang-00

Document Type Active Internet-Draft (individual)
Authors Italo Busi  , Aihua Guo  , Sergio Belotti 
Last updated 2021-10-22
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CCAMP Working Group                                              I. Busi
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                  A. Guo
Expires: 25 April 2022                            Futurewei Technologies
                                                              S. Belotti
                                                                   Nokia
                                                         22 October 2021

  YANG Data Models for requesting Path Computation in Optical Networks
            draft-gbb-ccamp-optical-path-computation-yang-00

Abstract

   This document describes YANG data models for Remote Procedure Calls
   (RPCs) to request Path Computation in Optical Networks (OTN, WSON and
   Flexi-grid).

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

Status of This Memo

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

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 25 April 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology and Notations . . . . . . . . . . . . . . . .   3
     1.2.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Prefix in Data Node Names . . . . . . . . . . . . . . . .   3
   2.  YANG Data Models for Optical Path Computation . . . . . . . .   4
     2.1.  YANG Models Overview  . . . . . . . . . . . . . . . . . .   4
     2.2.  Attributes Augmentation . . . . . . . . . . . . . . . . .   5
     2.3.  Bandwidth Augmentation  . . . . . . . . . . . . . . . . .   6
     2.4.  Label Augmentations . . . . . . . . . . . . . . . . . . .   6
   3.  Optical Path Computation Tree Diagrams  . . . . . . . . . . .   6
     3.1.  WSON Path Computation Tree Diagrams . . . . . . . . . . .   6
     3.2.  Flexi-grid Path Computation Tree Diagrams . . . . . . . .  10
     3.3.  OTN Path Computation Tree Diagrams  . . . . . . . . . . .  13
   4.  YANG Models for Optical Path Computation  . . . . . . . . . .  17
     4.1.  YANG Model for WSON Path Computation  . . . . . . . . . .  17
     4.2.  YANG Model for Flexi-grid Path Computation  . . . . . . .  23
     4.3.  YANG Model for OTN Path Computation . . . . . . . . . . .  29
   5.  Manageability Considerations  . . . . . . . . . . . . . . . .  35
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  35
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  35
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  35
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  35
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  37
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  37
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  37
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  37

1.  Introduction

   [I-D.ietf-teas-yang-path-computation] describes some use cases, where
   a client needs to request underlying SDN controllers for path
   computation.  In some of these use cases the underlying SDN
   controller can control a single-layer (OTN, WSON or Flexi-grid) or
   multi-layer Optical network.

   This document define YANG data models, which augment the generic Path
   Computation RPC defined in [I-D.ietf-teas-yang-path-computation],
   with technology-specific augmentations required to request path
   computation to an underlying Optical SDN controller.  These models
   allow a client to delegate path computation tasks to the underlying
   Optical SDN controller without having to obtain optical-layer
   information from the controller and performing feasible path

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   computation itself.  This is especially helpful in cases where
   computing optically-feasible paths requires knowledge of physical-
   layer states, such as optical impairments, which are visible only to
   the Optical controller.

   The YANG data model defined in this document conforms to the Network
   Management Datastore Architecture [RFC8342].

1.1.  Terminology and Notations

   Refer to [RFC7446] and [RFC7581] for the key terms used in this
   document.  The following terms are defined in [RFC7950] and are not
   redefined here:

   *  client

   *  server

   *  augment

   *  data model

   *  data node

   The following terms are defined in [RFC6241] and are not redefined
   here:

   *  configuration data

   *  state data

   The terminology for describing YANG data models is found in
   [RFC7950].

1.2.  Tree Diagram

   A simplified graphical representation of the data model is used in
   Section 3 of this document.  The meaning of the symbols in these
   diagrams is defined in [RFC8340].

1.3.  Prefix in Data Node Names

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

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      +==============+==================================+===========+
      | Prefix       | YANG module                      | Reference |
      +==============+==================================+===========+
      | l0-types     | ietf-layer0-types                | [RFC9093] |
      +--------------+----------------------------------+-----------+
      | l0-types-ext | ietf-layer0-types-ext            | [RFCYYYY] |
      +--------------+----------------------------------+-----------+
      | l0-types     | ietf-layer0-types                | [RFC8776] |
      +--------------+----------------------------------+-----------+
      | l1-types     | ietf-layer1-types                | [RFCZZZZ] |
      +--------------+----------------------------------+-----------+
      | te           | ietf-te                          | [RFCKKKK] |
      +--------------+----------------------------------+-----------+
      | tep          | ietf-te-path-computation         | [RFCJJJJ] |
      +--------------+----------------------------------+-----------+
      | flexg-pc     | ietf-flexi-grid-path-computation | RFCXXXX   |
      +--------------+----------------------------------+-----------+
      | wson-pc      | ietf-wson-path-computation       | RFCXXXX   |
      +--------------+----------------------------------+-----------+
      | otn-pc       | ietf-otn-path-computation        | RFCXXXX   |
      +--------------+----------------------------------+-----------+

              Table 1: Prefixes and corresponding YANG modules

   RFC Editor Note: Please replace XXXX with the RFC number assigned to
   this document.  Please replace YYYY with the RFC number assigned to
   [I-D.ietf-ccamp-layer0-types-ext].  Please replace ZZZZ with the RFC
   number assigned to [I-D.ietf-ccamp-layer1-types].  Please replace
   KKKK with the RFC number assigned to [I-D.ietf-teas-yang-te].  Please
   replace JJJJ with the RFC number assigned to
   [I-D.ietf-teas-yang-path-computation].  Please remove this note.

2.  YANG Data Models for Optical Path Computation

2.1.  YANG Models Overview

   The YANG data models for requesting WSON, Flexi-grid and OTN path
   computation are defined as augmentations of the generic Path
   Computation RPC defined in [I-D.ietf-teas-yang-path-computation], as
   shown in Figure 1.

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                       +--------------------------+    o: augment
          TE generic   | ietf-te-path-computation |
                       +--------------------------+
                             o      o      o
                             |      |      |
                             |      |      |
                 +-----------+      |      +-----------+
                 |                  |                  |
                 |                  |                  |
                 |                  |                  |
                 |    +---------------------------+    |
                 |    | ietf-otn-path-computation |    |
                 |    +---------------------------+    |
                 |                 OTN                 |
                 |                                     |
                 |                                     |
   +----------------------------+                      |
   | ietf-wson-path-computation |                      |
   +----------------------------+                      |
               WSON                                    |
                                   +----------------------------------+
                                   | ietf-flexi-grid-path-computation |
                                   +----------------------------------+
                                               Flexi-grid

      Figure 1: Relationship between WSON, Flexi-grid, OTN and TE path
                             computation models

   The entities and TE attributes, such as requested path and tunnel
   attributes, defined in [I-D.ietf-teas-yang-path-computation], are
   still applicable when requestiong WSON, Flexi-grid and OTN path
   computation and the models defined in this document only specifies
   the additional technology-specific attributes/information, using the
   attributes defined in [RFC9093], [I-D.ietf-ccamp-layer0-types-ext]
   and [I-D.ietf-ccamp-layer1-types].

   The YANG modules ietf-wson-path-computation, ietf-flexi-grid-path-
   computation and ietf-otn-path-computation defined in this document
   conforms to the Network Management Datastore Architecture (NMDA)
   defined in [RFC8342].

2.2.  Attributes Augmentation

   The common characteristics for layer 0 (WSON and Flexi-grid) tunnels
   are under definition in [I-D.ietf-ccamp-layer0-types-ext] and re-used
   in the ietf-wson-path-computation and ietf-flexi-grid-path-
   computation YANG models

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2.3.  Bandwidth Augmentation

   As described in Section 4.2 of [RFC7699], there is some overlap
   between bandwidth and label in layer0.

   The WSON and flexi-grid label resource information described in
   Section 2.4, is sufficient to describe also the spectrum resources
   within WSON and flexi-grid networks.  Therefore, the model does not
   define any augmentation for the te-bandwidth containers defined in
   [I-D.ietf-teas-yang-path-computation].

   The OTN path computation model augments all the occurrences of the
   te-bandwidth container with the OTN technology specific attributes
   using the otn-link-bandwidth and otn-path-bandwidth groupings defined
   in [I-D.ietf-ccamp-layer1-types].

2.4.  Label Augmentations

   The models augment all the occurrences of the label-restriction list
   with WSON, Flexi-grid and OTN technology specific attributes using
   the l0-label-range-info and flexi-grid-label-range-info groupings
   defined in [RFC9093] and the otn-label-range-info grouping defined in
   [I-D.ietf-ccamp-layer1-types].

   Moreover, the models augment all the occurrences of the te-label
   container with the WSON, Flexi-grid and OTN technology specific
   attributes using the wson-label-start-end, wson-label-hop, wson-
   label-step, flexi-grid-label-start-end, flexi-grid-label-hop and
   flexi-grid-label-step defined in [RFC9093] and the otn-label-start-
   end, otn-label-hop and otn-label-step groupings defined in
   [I-D.ietf-ccamp-layer1-types].

3.  Optical Path Computation Tree Diagrams

3.1.  WSON Path Computation Tree Diagrams

   Figure 2 below shows the tree diagram of the YANG data model defined
   in module ietf-wson-path-computation.yang.

   module: ietf-wson-path-computation

     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request:
       +-- fec-type?                identityref
       +-- termination-type?        identityref
       +-- bit-stuffing?            boolean
       +-- wavelength-assignment?   identityref
     augment /te:tunnels-path-compute/te:input/te:path-compute-info

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               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- grid-type?   identityref
       +-- priority?    uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- grid-type?   identityref
       +-- priority?    uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-exclude-objects
               /tepc:route-object-exclude-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- (single-or-super-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +-- subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?                    l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-include-objects
               /tepc:route-object-include-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- (single-or-super-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +-- subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?                    l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-exclude-always/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)

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             |  +-- (single-or-super-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +-- subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?                    l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-include-exclude/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- (single-or-super-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +-- subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?                    l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- dwdm-n?   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?   l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- dwdm-n?   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?   l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(wson)
          +-- (l0-grid-type)?
             +--:(dwdm)

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             |  +-- wson-dwdm-channel-spacing?   identityref
             +--:(cwdm)
                +-- wson-cwdm-channel-spacing?   identityref
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- dwdm-n?   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?   l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- dwdm-n?   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?   l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(wson)
          +-- (l0-grid-type)?
             +--:(dwdm)
             |  +-- wson-dwdm-channel-spacing?   identityref
             +--:(cwdm)
                +-- wson-cwdm-channel-spacing?   identityref
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:synchronization/tepc:exclude-objects/tepc:excludes
               /tepc:type/tepc:label/tepc:label-hop/tepc:te-label
               /tepc:technology:
       +--:(wson)
          +-- (grid-type)?
             +--:(dwdm)
             |  +-- (single-or-super-channel)?
             |     +--:(single)
             |     |  +-- dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +-- subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +-- cwdm-n?                    l0-types:cwdm-n
     augment /te:tunnels-path-compute/te:output/te:path-compute-result

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               /tepc:response/tepc:computed-paths-properties
               /tepc:computed-path-properties/tepc:path-properties
               /tepc:path-route-objects/tepc:path-route-object/tepc:type
               /tepc:label/tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(wson)
          +--ro (grid-type)?
             +--:(dwdm)
             |  +--ro (single-or-super-channel)?
             |     +--:(single)
             |     |  +--ro dwdm-n?              l0-types:dwdm-n
             |     +--:(super)
             |        +--ro subcarrier-dwdm-n*   l0-types:dwdm-n
             +--:(cwdm)
                +--ro cwdm-n?                    l0-types:cwdm-n

                Figure 2: WSON path computation tree diagram

3.2.  Flexi-grid Path Computation Tree Diagrams

   Figure 3 below shows the tree diagram of the YANG data model defined
   in module ietf-flexi-grid-path-computation.yang.

   module: ietf-flexi-grid-path-computation

     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request:
       +-- fec-type?                identityref
       +-- termination-type?        identityref
       +-- bit-stuffing?            boolean
       +-- wavelength-assignment?   identityref
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- grid-type?    identityref
       +-- priority?     uint8
       +-- flexi-grid
          +-- slot-width-granularity?   identityref
          +-- min-slot-width-factor?    uint16
          +-- max-slot-width-factor?    uint16
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- grid-type?    identityref
       +-- priority?     uint8
       +-- flexi-grid
          +-- slot-width-granularity?   identityref
          +-- min-slot-width-factor?    uint16
          +-- max-slot-width-factor?    uint16

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     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-exclude-objects
               /tepc:route-object-exclude-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- (single-or-super-channel)?
             +--:(single)
             |  +-- flexi-n?              l0-types:flexi-n
             |  +-- flexi-m?              l0-types:flexi-m
             +--:(super)
                +-- subcarrier-flexi-n* [flexi-n]
                   +-- flexi-n    l0-types:flexi-n
                   +-- flexi-m?   l0-types:flexi-m
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-include-objects
               /tepc:route-object-include-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- (single-or-super-channel)?
             +--:(single)
             |  +-- flexi-n?              l0-types:flexi-n
             |  +-- flexi-m?              l0-types:flexi-m
             +--:(super)
                +-- subcarrier-flexi-n* [flexi-n]
                   +-- flexi-n    l0-types:flexi-n
                   +-- flexi-m?   l0-types:flexi-m
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-exclude-always/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- (single-or-super-channel)?
             +--:(single)
             |  +-- flexi-n?              l0-types:flexi-n
             |  +-- flexi-m?              l0-types:flexi-m
             +--:(super)
                +-- subcarrier-flexi-n* [flexi-n]
                   +-- flexi-n    l0-types:flexi-n
                   +-- flexi-m?   l0-types:flexi-m
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-include-exclude/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(flexi-grid)

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          +-- (single-or-super-channel)?
             +--:(single)
             |  +-- flexi-n?              l0-types:flexi-n
             |  +-- flexi-m?              l0-types:flexi-m
             +--:(super)
                +-- subcarrier-flexi-n* [flexi-n]
                   +-- flexi-n    l0-types:flexi-n
                   +-- flexi-m?   l0-types:flexi-m
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-n?   l0-types:flexi-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-n?   l0-types:flexi-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-grid-channel-spacing?   identityref
          +-- flexi-n-step?                 uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-n?   l0-types:flexi-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-n?   l0-types:flexi-n
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(flexi-grid)
          +-- flexi-grid-channel-spacing?   identityref
          +-- flexi-n-step?                 uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:synchronization/tepc:exclude-objects/tepc:excludes

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               /tepc:type/tepc:label/tepc:label-hop/tepc:te-label
               /tepc:technology:
       +--:(flexi-grid)
          +-- (single-or-super-channel)?
             +--:(single)
             |  +-- flexi-n?              l0-types:flexi-n
             |  +-- flexi-m?              l0-types:flexi-m
             +--:(super)
                +-- subcarrier-flexi-n* [flexi-n]
                   +-- flexi-n    l0-types:flexi-n
                   +-- flexi-m?   l0-types:flexi-m
     augment /te:tunnels-path-compute/te:output/te:path-compute-result
               /tepc:response/tepc:computed-paths-properties
               /tepc:computed-path-properties/tepc:path-properties
               /tepc:path-route-objects/tepc:path-route-object/tepc:type
               /tepc:label/tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(flexi-grid)
          +--ro (single-or-super-channel)?
             +--:(single)
             |  +--ro flexi-n?              l0-types:flexi-n
             |  +--ro flexi-m?              l0-types:flexi-m
             +--:(super)
                +--ro subcarrier-flexi-n* [flexi-n]
                   +--ro flexi-n    l0-types:flexi-n
                   +--ro flexi-m?   l0-types:flexi-m

             Figure 3: Flexi-grid path computation tree diagram

3.3.  OTN Path Computation Tree Diagrams

   Figure 4 below shows the tree diagram of the YANG data model defined
   in module ietf-otn-path-computation.yang.

   module: ietf-otn-path-computation

     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:te-bandwidth/tepc:technology:
       +--:(otn)
          +-- otn
             +-- odu-type?                     identityref
             +-- (oduflex-type)?
                +--:(generic)
                |  +-- nominal-bit-rate        uint64
                +--:(cbr)
                |  +-- client-type             identityref
                +--:(gfp-n-k)
                |  +-- gfp-n                   uint8
                |  +-- gfp-k?                  gfp-k

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                +--:(flexe-client)
                |  +-- flexe-client            flexe-client-rate
                +--:(flexe-aware)
                |  +-- flexe-aware-n           uint16
                +--:(packet)
                   +-- opuflex-payload-rate    uint64
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:tunnel-attributes/tepc:te-bandwidth
               /tepc:technology:
       +--:(otn)
          +-- otn
             +-- odu-type?                     identityref
             +-- (oduflex-type)?
                +--:(generic)
                |  +-- nominal-bit-rate        uint64
                +--:(cbr)
                |  +-- client-type             identityref
                +--:(gfp-n-k)
                |  +-- gfp-n                   uint8
                |  +-- gfp-k?                  gfp-k
                +--:(flexe-client)
                |  +-- flexe-client            flexe-client-rate
                +--:(flexe-aware)
                |  +-- flexe-aware-n           uint16
                +--:(packet)
                   +-- opuflex-payload-rate    uint64
     augment /te:tunnels-path-compute/te:output/te:path-compute-result
               /tepc:response/tepc:computed-paths-properties
               /tepc:computed-path-properties/tepc:path-properties
               /tepc:te-bandwidth/tepc:technology:
       +--:(otn)
          +--ro otn
             +--ro odu-type?                     identityref
             +--ro (oduflex-type)?
                +--:(generic)
                |  +--ro nominal-bit-rate        uint64
                +--:(cbr)
                |  +--ro client-type             identityref
                +--:(gfp-n-k)
                |  +--ro gfp-n                   uint8
                |  +--ro gfp-k?                  gfp-k
                +--:(flexe-client)
                |  +--ro flexe-client            flexe-client-rate
                +--:(flexe-aware)
                |  +--ro flexe-aware-n           uint16
                +--:(packet)
                   +--ro opuflex-payload-rate    uint64
     augment /te:tunnels-path-compute/te:input/te:path-compute-info

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               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- range-type?      otn-label-range-type
       +-- tsg?             identityref
       +-- odu-type-list*   identityref
       +-- priority?        uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction:
       +-- range-type?      otn-label-range-type
       +-- tsg?             identityref
       +-- odu-type-list*   identityref
       +-- priority?        uint8
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-exclude-objects
               /tepc:route-object-exclude-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- otn-tpn?   otn-tpn
          +-- tsg?       identityref
          +-- ts-list?   string
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:optimizations/tepc:algorithm
               /tepc:metric/tepc:optimization-metric
               /tepc:explicit-route-include-objects
               /tepc:route-object-include-object/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- otn-tpn?   otn-tpn
          +-- tsg?       identityref
          +-- ts-list?   string
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-exclude-always/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- otn-tpn?   otn-tpn
          +-- tsg?       identityref
          +-- ts-list?   string
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:explicit-route-objects-always
               /tepc:route-object-include-exclude/tepc:type/tepc:label
               /tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- otn-tpn?   otn-tpn
          +-- tsg?       identityref

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          +-- ts-list?   string
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)
             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)
             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-in-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)
             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-start/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)
             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-end/tepc:te-label/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)

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             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:path-request/tepc:path-out-segment
               /tepc:label-restrictions/tepc:label-restriction
               /tepc:label-step/tepc:technology:
       +--:(otn)
          +-- (range-type)?
             +--:(trib-port)
             |  +-- otn-tpn?   otn-tpn
             +--:(trib-slot)
                +-- otn-ts?    otn-ts
     augment /te:tunnels-path-compute/te:input/te:path-compute-info
               /tepc:synchronization/tepc:exclude-objects/tepc:excludes
               /tepc:type/tepc:label/tepc:label-hop/tepc:te-label
               /tepc:technology:
       +--:(otn)
          +-- otn-tpn?   otn-tpn
          +-- tsg?       identityref
          +-- ts-list?   string
     augment /te:tunnels-path-compute/te:output/te:path-compute-result
               /tepc:response/tepc:computed-paths-properties
               /tepc:computed-path-properties/tepc:path-properties
               /tepc:path-route-objects/tepc:path-route-object/tepc:type
               /tepc:label/tepc:label-hop/tepc:te-label/tepc:technology:
       +--:(otn)
          +--ro otn-tpn?   otn-tpn
          +--ro tsg?       identityref
          +--ro ts-list?   string

                Figure 4: OTN path computation tree diagram

4.  YANG Models for Optical Path Computation

4.1.  YANG Model for WSON Path Computation

   <CODE BEGINS> file "ietf-wson-path-computation@2021-10-15.yang"
   module ietf-wson-path-computation {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-wson-path-computation";
     prefix "wson-pc";

     import ietf-te-path-computation {
       prefix "tepc";
       revision-date "2021-09-06";
       reference
       "I-D.ietf-teas-yang-path-computation-14: Yang model

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       for requesting Path Computation.";
     }

     import ietf-te {
       prefix "te";
       revision-date "2021-02-20";
       reference
         "I-D.ietf-teas-yang-te-19: A YANG Data Model for Traffic
         Engineering Tunnels and Interfaces. ";
     }

     import ietf-layer0-types {
       prefix "l0-types";
     }

     import ietf-layer0-types-ext {
       prefix "l0-types-ext";
     }

     organization
       "IETF CCAMP Working Group";
     contact
       "WG Web:   <http://tools.ietf.org/wg/ccamp/>
        WG List:  <mailto:ccamp@ietf.org>

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

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

        Editor:   Sergio Belotti
                  <mailto:sergio.belotti@nokia.com>";

     description
       "This module defines a model for requesting
       WSON Path Computation.

       The model fully conforms to the Network Management
       Datastore Architecture (NMDA).

       Copyright (c) 2021 IETF Trust and the persons
       identified as authors of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD License
       set forth in Section 4.c of the IETF Trust's Legal Provisions

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       Relating to IETF Documents
       (https://trustee.ietf.org/license-info).

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

     revision "2021-10-15" {
       description
         "Initial version.";
       reference
         "RFC XXXX: YANG Model for OTN and Optical Path Computation";
       // RFC Ed.: replace XXXX with actual RFC number, update date
       // information and remove this note
     }

    /*
     * Data nodes
     */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request" {
       description
          "Augment with additional constraints for WSON paths.";
       uses l0-types-ext:l0-tunnel-attributes;
       uses l0-types-ext:l0-path-constraints;
     }

     /*
      * Augment TE label range information
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the ingress segment
         of the requested path.";
       uses l0-types:l0-label-range-info;
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the egress segment
         of the requested path.";
       uses l0-types:l0-label-range-info;
     }

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     /*
      * Augment TE label.
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"
           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-exclude-objects/"
           + "tepc:route-object-exclude-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects excluded by the path computation of the requested
         path.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"
           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-include-objects/"
           + "tepc:route-object-include-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects included by the path computation of the requested
         path.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"
           + "tepc:route-object-exclude-always/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects always
         excluded by the path computation of the requested path.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"

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           + "tepc:route-object-include-exclude/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects included
         or excluded by the path computation of the requested path.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range start for the ingress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range end for the ingress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range step for the ingress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"

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           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range start for the egress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range end for the egress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range end for the egress segment
         of the requested path.";
       case wson {
         uses l0-types:wson-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:synchronization/tepc:exclude-objects/tepc:excludes/"
           + "tepc:type/tepc:label/tepc:label-hop/"
           + "tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects to always
         exclude from synchronized path computation.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:output/"
           + "te:path-compute-result/tepc:response/"

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           + "tepc:computed-paths-properties/"
           + "tepc:computed-path-properties/tepc:path-properties/"
           + "tepc:path-route-objects/tepc:path-route-object/"
           + "tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the route object of the computed
         path.";
       case wson {
         uses l0-types:wson-label-hop;
       }
     }
   }
   <CODE ENDS>

                Figure 5: WSON path computation YANG module

4.2.  YANG Model for Flexi-grid Path Computation

   <CODE BEGINS> file "ietf-flexi-grid-path-computation@2021-10-15.yang"
   module ietf-flexi-grid-path-computation {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-flexi-grid-path-computation";
     prefix "flexg-pc";

     import ietf-te-path-computation {
       prefix "tepc";
       revision-date "2021-09-06";
       reference
       "I-D.ietf-teas-yang-path-computation-14: Yang model
       for requesting Path Computation.";
     }

     import ietf-te {
       prefix "te";
       revision-date "2021-02-20";
       reference
         "I-D.ietf-teas-yang-te-19: A YANG Data Model for Traffic
         Engineering Tunnels and Interfaces. ";
     }

     import ietf-layer0-types {
       prefix "l0-types";
     }

     import ietf-layer0-types-ext {
       prefix "l0-types-ext";

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     }

     organization
       "IETF CCAMP Working Group";
     contact
       "WG Web:   <http://tools.ietf.org/wg/ccamp/>
        WG List:  <mailto:ccamp@ietf.org>

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

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

        Editor:   Sergio Belotti
                  <mailto:sergio.belotti@nokia.com>";

     description
       "This module defines a model for requesting
       Flexi-grid Path Computation.

       The model fully conforms to the Network Management
       Datastore Architecture (NMDA).

       Copyright (c) 2021 IETF Trust and the persons
       identified as authors of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD License
       set forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents
       (https://trustee.ietf.org/license-info).

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

     revision "2021-10-15" {
       description
         "Initial version.";
       reference
         "RFC XXXX: YANG Model for OTN and Optical Path Computation";
       // RFC Ed.: replace XXXX with actual RFC number, update date
       // information and remove this note
     }

    /*
     * Data nodes

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     */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request" {
       description
          "Augment with additional constraints flexi-grid
           media channel.";
       uses l0-types-ext:l0-tunnel-attributes;
       uses l0-types-ext:l0-path-constraints;
     }

     /*
      * Augment TE label range information
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the ingress segment
         of the requested path.";
       uses l0-types:flexi-grid-label-range-info;
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the egress segment
         of the requested path.";
       uses l0-types:flexi-grid-label-range-info;
     }

     /*
      * Augment TE label.
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"
           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-exclude-objects/"
           + "tepc:route-object-exclude-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects excluded by the path computation of the requested
         path.";
       case flexi-grid {

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         uses l0-types:flexi-grid-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"
           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-include-objects/"
           + "tepc:route-object-include-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects included by the path computation of the requested
         path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"
           + "tepc:route-object-exclude-always/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects always
         excluded by the path computation of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"
           + "tepc:route-object-include-exclude/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects included
         or excluded by the path computation of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description

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         "Augment TE label range start for the ingress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range end for the ingress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range step for the ingress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range start for the egress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description

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         "Augment TE label range end for the egress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range end for the egress segment
         of the requested path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:synchronization/tepc:exclude-objects/tepc:excludes/"
           + "tepc:type/tepc:label/tepc:label-hop/"
           + "tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects to always
         exclude from synchronized path computation.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:output/"
           + "te:path-compute-result/tepc:response/"
           + "tepc:computed-paths-properties/"
           + "tepc:computed-path-properties/tepc:path-properties/"
           + "tepc:path-route-objects/tepc:path-route-object/"
           + "tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the route object of the computed
         path.";
       case flexi-grid {
         uses l0-types:flexi-grid-label-hop;
       }
     }
   }
   <CODE ENDS>

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             Figure 6: Flexi-grid path computation YANG module

4.3.  YANG Model for OTN Path Computation

   <CODE BEGINS> file "ietf-otn-path-computation@2021-10-07.yang"
   module ietf-otn-path-computation {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-otn-path-computation";
     prefix "otn-pc";

     import ietf-te-path-computation {
       prefix "tepc";
       revision-date "2021-09-06";
       reference
       "I-D.ietf-teas-yang-path-computation-14: Yang model
       for requesting Path Computation.";
     }

     import ietf-te {
       prefix "te";
       revision-date "2021-02-20";
       reference
         "I-D.ietf-teas-yang-te-19: A YANG Data Model for Traffic
         Engineering Tunnels and Interfaces. ";
     }

     import ietf-layer1-types {
       prefix "l1-types";
       reference
       "I-D.ietf-ccamp-layer1-types:
        A YANG Data Model for Layer 1 Types. ";
     }

     organization
       "IETF CCAMP Working Group";
     contact
       "WG Web:   <http://tools.ietf.org/wg/ccamp/>
        WG List:  <mailto:ccamp@ietf.org>

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

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

        Editor:   Sergio Belotti
                  <mailto:sergio.belotti@nokia.com>";

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     description
       "This module defines a model for requesting
       OTN Path Computation.

       The model fully conforms to the Network Management
       Datastore Architecture (NMDA).

       Copyright (c) 2021 IETF Trust and the persons
       identified as authors of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD License
       set forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents
       (https://trustee.ietf.org/license-info).

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

     revision "2021-10-07" {
       description
         "Initial version.";
       reference
         "RFC XXXX: YANG Model for OTN and Optical Path Computation";
       // RFC Ed.: replace XXXX with actual RFC number, update date
       // information and remove this note
     }

    /*
     * Data nodes
     */

     /*
      * Augment TE bandwidth
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:te-bandwidth/tepc:technology" {
       description
         "Augment TE bandwidth of the requested path.";
       case otn {
         uses l1-types:otn-path-bandwidth;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:tunnel-attributes/tepc:te-bandwidth/"

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           + "tepc:technology" {
       description
         "Augment TE bandwidth of the requested tunnel attributes.";
       case otn {
         uses l1-types:otn-path-bandwidth;
       }
     }

     augment "/te:tunnels-path-compute/te:output/"
           + "te:path-compute-result/tepc:response/"
           + "tepc:computed-paths-properties/"
           + "tepc:computed-path-properties/tepc:path-properties/"
           + "tepc:te-bandwidth/tepc:technology" {
       description
         "Augment TE bandwidth of the computed path properties.";
       case otn {
         uses l1-types:otn-path-bandwidth;
       }
     }

     /*
      * Augment TE label range information
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the ingress segment
         of the requested path.";
       uses l1-types:otn-label-range-info;
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction" {
       description
         "Augment TE label range information for the egress segment
         of the requested path.";
       uses l1-types:otn-label-range-info;
     }

     /*
      * Augment TE label.
      */

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"

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           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-exclude-objects/"
           + "tepc:route-object-exclude-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects excluded by the path computation of the requested
         path.";
       case otn {
         uses l1-types:otn-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:optimizations/tepc:algorithm/"
           + "tepc:metric/tepc:optimization-metric/"
           + "tepc:explicit-route-include-objects/"
           + "tepc:route-object-include-object/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the optimization of the explicit
         route objects included by the path computation of the requested
         path.";
       case otn {
         uses l1-types:otn-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"
           + "tepc:route-object-exclude-always/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects always
         excluded by the path computation of the requested path.";
       case otn {
         uses l1-types:otn-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:explicit-route-objects-always/"
           + "tepc:route-object-include-exclude/tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects included
         or excluded by the path computation of the requested path.";
       case otn {

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         uses l1-types:otn-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range start for the ingress segment
         of the requested path.";
       case otn {
         uses l1-types:otn-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range end for the ingress segment
         of the requested path.";
       case otn {
         uses l1-types:otn-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-in-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range step for the ingress segment
         of the requested path.";
       case otn {
         uses l1-types:otn-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-start/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range start for the egress segment
         of the requested path.";
       case otn {

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         uses l1-types:otn-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-end/tepc:te-label/tepc:technology" {
       description
         "Augment TE label range end for the egress segment
         of the requested path.";
       case otn {
         uses l1-types:otn-label-start-end;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:path-request/tepc:path-out-segment/"
           + "tepc:label-restrictions/tepc:label-restriction/"
           + "tepc:label-step/tepc:technology" {
       description
         "Augment TE label range end for the egress segment
         of the requested path.";
       case otn {
         uses l1-types:otn-label-step;
       }
     }

     augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
           + "tepc:synchronization/tepc:exclude-objects/tepc:excludes/"
           + "tepc:type/tepc:label/tepc:label-hop/"
           + "tepc:te-label/tepc:technology" {
       description
         "Augment TE label hop for the explicit route objects to always
         exclude from synchronized path computation.";
       case otn {
         uses l1-types:otn-label-hop;
       }
     }

     augment "/te:tunnels-path-compute/te:output/"
           + "te:path-compute-result/tepc:response/"
           + "tepc:computed-paths-properties/"
           + "tepc:computed-path-properties/tepc:path-properties/"
           + "tepc:path-route-objects/tepc:path-route-object/"
           + "tepc:type/tepc:label/"
           + "tepc:label-hop/tepc:te-label/tepc:technology" {
       description

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         "Augment TE label hop for the route object of the computed
         path.";
       case otn {
         uses l1-types:otn-label-hop;
       }
     }
   }
   <CODE ENDS>

                 Figure 7: OTN path computation YANG module

5.  Manageability Considerations

   TBD.

6.  Security Considerations

   <Add any security considerations>

7.  IANA Considerations

   <Add any IANA considerations>

8.  References

8.1.  Normative References

   [I-D.ietf-ccamp-layer0-types-ext]
              Beller, D., Belotti, S., Zheng, H., Busi, I., and E. L.
              Rouzic, "A YANG Data Model for Layer 0 Types - Revision
              2", Work in Progress, Internet-Draft, draft-ietf-ccamp-
              layer0-types-ext-00, 10 August 2021,
              <https://www.ietf.org/archive/id/draft-ietf-ccamp-layer0-
              types-ext-00.txt>.

   [I-D.ietf-ccamp-layer1-types]
              Zheng, H. and I. Busi, "A YANG Data Model for Layer 1
              Types", Work in Progress, Internet-Draft, draft-ietf-
              ccamp-layer1-types-11, 7 September 2021,
              <https://www.ietf.org/archive/id/draft-ietf-ccamp-layer1-
              types-11.txt>.

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   [I-D.ietf-teas-yang-path-computation]
              Busi, I., Belotti, S., Lopez, V., Sharma, A., and Y. Shi,
              "YANG Data Model for requesting Path Computation", Work in
              Progress, Internet-Draft, draft-ietf-teas-yang-path-
              computation-16, 6 September 2021,
              <https://www.ietf.org/archive/id/draft-ietf-teas-yang-
              path-computation-16.txt>.

   [I-D.ietf-teas-yang-te]
              Saad, T., Gandhi, R., Liu, X., Beeram, V. P., Bryskin, I.,
              and O. G. D. Dios, "A YANG Data Model for Traffic
              Engineering Tunnels, Label Switched Paths and Interfaces",
              Work in Progress, Internet-Draft, draft-ietf-teas-yang-te-
              27, 8 July 2021, <https://www.ietf.org/archive/id/draft-
              ietf-teas-yang-te-27.txt>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC7699]  Farrel, A., King, D., Li, Y., and F. Zhang, "Generalized
              Labels for the Flexi-Grid in Lambda Switch Capable (LSC)
              Label Switching Routers", RFC 7699, DOI 10.17487/RFC7699,
              November 2015, <https://www.rfc-editor.org/info/rfc7699>.

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

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8776]  Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
              "Common YANG Data Types for Traffic Engineering",
              RFC 8776, DOI 10.17487/RFC8776, June 2020,
              <https://www.rfc-editor.org/info/rfc8776>.

   [RFC9093]  Zheng, H., Lee, Y., Guo, A., Lopez, V., and D. King, "A
              YANG Data Model for Layer 0 Types", RFC 9093,
              DOI 10.17487/RFC9093, August 2021,
              <https://www.rfc-editor.org/info/rfc9093>.

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8.2.  Informative References

   [I-D.ietf-teas-actn-poi-applicability]
              Peruzzini, F., Bouquier, J., Busi, I., King, D., and D.
              Ceccarelli, "Applicability of Abstraction and Control of
              Traffic Engineered Networks (ACTN) to Packet Optical
              Integration (POI)", Work in Progress, Internet-Draft,
              draft-ietf-teas-actn-poi-applicability-03, 12 July 2021,
              <https://www.ietf.org/archive/id/draft-ietf-teas-actn-poi-
              applicability-03.txt>.

   [RFC7446]  Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
              "Routing and Wavelength Assignment Information Model for
              Wavelength Switched Optical Networks", RFC 7446,
              DOI 10.17487/RFC7446, February 2015,
              <https://www.rfc-editor.org/info/rfc7446>.

   [RFC7581]  Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
              J. Han, "Routing and Wavelength Assignment Information
              Encoding for Wavelength Switched Optical Networks",
              RFC 7581, DOI 10.17487/RFC7581, June 2015,
              <https://www.rfc-editor.org/info/rfc7581>.

Acknowledgments

   The authors of this document would like to thank the authors of
   [I-D.ietf-teas-actn-poi-applicability] for having identified the gap
   and requirements to trigger this work.

   This document was prepared using kramdown.

Contributors

   Daniel King
   Old Dog Consulting

   Email: daniel@olddog.co.uk

Authors' Addresses

   Italo Busi
   Huawei Technologies

   Email: italo.busi@huawei.com

Busi, et al.              Expires 25 April 2022                [Page 37]
Internet-Draft      Yang for Optical Path Computation       October 2021

   Aihua Guo
   Futurewei Technologies

   Email: aihuaguo.ietf@gmail.com

   Sergio Belotti
   Nokia

   Email: sergio.belotti@nokia.com

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