Internet-Draft Yang for Optical Path Computation October 2023
Busi, et al. Expires 22 April 2024 [Page]
Workgroup:
CCAMP Working Group
Internet-Draft:
draft-ietf-ccamp-optical-path-computation-yang-02
Published:
Intended Status:
Standards Track
Expires:
Authors:
I. Busi
Huawei Technologies
A. Guo
Futurewei Technologies
S. Belotti
Nokia

YANG Data Models for requesting Path Computation in Optical Networks

Abstract

This document provides a mechanism to request path computation in Optical Networks (WSON and Flexi-grid) by augmenting the Remote Procedure Calls (RPCs) defined in RFC YYYY.

[RFC EDITOR NOTE: Please replace RFC YYYY with the RFC number of draft-ietf-teas-yang-path-computation once it has been published.

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). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 22 April 2024.

1. Introduction

[I-D.ietf-teas-yang-path-computation] describes key 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 optical technologies, including Optical Transport Network (OTN), Wavelength Switched Optical Networks (WSON), Flexi-grid, and multi-layer Optical network.

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

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 Table 1.

Table 1: Prefixes and corresponding YANG modules
Prefix YANG module Reference
l0-types ietf-layer0-types [RFCZZZZ]
te ietf-te [RFCKKKK]
tepc ietf-te-path-computation [RFCYYYY]
wson-pc ietf-wson-path-computation RFCXXXX
flexg-pc ietf-flexi-grid-path-computation RFCXXXX

RFC Editor Note: Please replace XXXX with the RFC number assigned to this document. Please replace ZZZZ with the RFC number assigned to [I-D.ietf-ccamp-rfc9093-bis]. Please replace KKKK with the RFC number assigned to [I-D.ietf-teas-yang-te]. Please replace YYYY 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 and Flexi-grid 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.

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

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

The entities and Traffic Engineering (TE) attributes, such as requested path and tunnel attributes, defined in [I-D.ietf-teas-yang-path-computation], are still applicable when requesting WSON and Flexi-grid path computation and the models defined in this document only specifies the additional technology-specific attributes/information, using the attributes defined in [I-D.ietf-ccamp-rfc9093-bis].

2.2. Attributes Augmentation

The common characteristics for layer 0 (WSON and Flexi-grid) tunnels are under definition in [I-D.ietf-ccamp-rfc9093-bis] and re-used in the ietf-wson-path-computation and ietf-flexi-grid-path-computation YANG models

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].

2.4. Label Augmentations

The models augment all the occurrences of the label-restriction list with WSON and Flexi-grid technology-specific attributes using the l0-label-range-info and flexi-grid-label-range-info groupings defined in [I-D.ietf-ccamp-rfc9093-bis].

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 [I-D.ietf-ccamp-rfc9093-bis].

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:
    +-- bit-stuffing?            boolean
    +-- wavelength-assignment?   identityref
    +-- gsnr-margin?             snr
  augment /te:tunnels-path-compute/te:output/te:path-compute-result
            /tepc:response/tepc:computed-paths-properties
            /tepc:computed-path-properties/tepc:path-properties:
    +--ro estimated-gsnr?   snr
  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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   string
  augment /te:tunnels-path-compute/te:input/te:path-compute-info
            /tepc:synchronization/tepc:exclude-objects/tepc:excludes
            /tepc:type:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +--ro oms-element-uid?   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:
    +-- 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)
          |  +-- (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)
          |  +-- 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
            /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:
    +-- bit-stuffing?            boolean
    +-- wavelength-assignment?   identityref
    +-- gsnr-margin?             snr
  augment /te:tunnels-path-compute/te:output/te:path-compute-result
            /tepc:response/tepc:computed-paths-properties
            /tepc:computed-path-properties/tepc:path-properties:
    +--ro estimated-gsnr?   snr
  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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +-- oms-element-uid?   string
  augment /te:tunnels-path-compute/te:input/te:path-compute-info
            /tepc:synchronization/tepc:exclude-objects/tepc:excludes
            /tepc:type:
    +--:(oms-element)
       +-- oms-element-uid?   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:
    +--:(oms-element)
       +--ro oms-element-uid?   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:
    +-- 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
  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)
       +-- (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
            /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

4. YANG Models for Optical Path Computation

4.1. YANG Model for WSON Path Computation

<CODE BEGINS> file "ietf-wson-path-computation@2022-09-08.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
      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";
    reference
      "I-D.ietf-ccamp-rfc9093-bis: A YANG Data Model for Layer 0
      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>";

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

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

    Copyright (c) 2022 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 Revised 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 "2022-09-08" {
    description
      "Initial version.";
    reference
      "RFC XXXX: YANG Data Models for requesting Path Computation
      in Optical Networks.";
    // 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:l0-tunnel-attributes;
    uses l0-types:l0-path-constraints;
  }

  augment "/te:tunnels-path-compute/te:output/"
        + "te:path-compute-result/tepc:response/"
        + "tepc:computed-paths-properties/"
        + "tepc:computed-path-properties/tepc:path-properties" {
    description
       "Augment with additional properties for WSON paths.";
    uses l0-types:l0-path-properties;
  }

  /*
   * Augment Route 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-exclude-objects/"
        + "tepc:route-object-exclude-object/tepc:type" {
    description
      "Augment the route hop for the optimization of the explicit
      route objects excluded by the path computation of the requested
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the optimization of the explicit
      route objects included by the path computation of the requested
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the explicit route objects always
      excluded by the path computation of the requested path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the explicit route objects included
      or excluded by the path computation of the requested path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
        + "tepc:synchronization/tepc:exclude-objects/tepc:excludes/"
        + "tepc:type" {
    description
      "Augment the route hop for the explicit route objects to always
      exclude from synchronized path computation.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the route object of the computed
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  /*
   * 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;
  }

  /*
   * 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/"
        + "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/"
        + "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/"
        + "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 4: WSON path computation YANG module

4.2. YANG Model for Flexi-grid Path Computation

<CODE BEGINS> file "ietf-flexi-grid-path-computation@2022-09-08.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";
    reference
      "I-D.ietf-ccamp-rfc9093-bis: A YANG Data Model for Layer 0
      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>";

  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) 2022 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 Revised 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 "2022-09-08" {
    description
      "Initial version.";
    reference
      "RFC XXXX: YANG Data Models for requesting Path Computation
      in Optical Networks.";
    // 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 flexi-grid
        media channel.";
    uses l0-types:l0-tunnel-attributes;
    uses l0-types:l0-path-constraints;
  }

  augment "/te:tunnels-path-compute/te:output/"
        + "te:path-compute-result/tepc:response/"
        + "tepc:computed-paths-properties/"
        + "tepc:computed-path-properties/tepc:path-properties" {
    description
       "Augment with additional properties for Flexi-grid paths.";
    uses l0-types:l0-path-properties;
  }

  /*
   * Augment Route 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-exclude-objects/"
        + "tepc:route-object-exclude-object/tepc:type" {
    description
      "Augment the route hop for the optimization of the explicit
      route objects excluded by the path computation of the requested
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the optimization of the explicit
      route objects included by the path computation of the requested
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the explicit route objects always
      excluded by the path computation of the requested path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the explicit route objects included
      or excluded by the path computation of the requested path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  augment "/te:tunnels-path-compute/te:input/te:path-compute-info/"
        + "tepc:synchronization/tepc:exclude-objects/tepc:excludes/"
        + "tepc:type" {
    description
      "Augment the route hop for the explicit route objects to always
      exclude from synchronized path computation.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  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" {
    description
      "Augment the route hop for the route object of the computed
      path.";
    case oms-element {
      leaf oms-element-uid {
        type string;
        description
          "The unique id of the OMS element.";
      }
      description
        "The OMS element route hop type";
    }
  }

  /*
   * 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 {
      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
      "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
      "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>
Figure 5: Flexi-grid path computation YANG module

5. Manageability Considerations

This document provides a method for requesting path computations for WSON and Flexi-Grid tunnels. Consideration of mechanisms to gather and collate information required for the path computations will be necessary. Furthermore, storing path computation requests and responses and triggering actions will also need to be carefully managed and secured.

Future versions of this document will contain additional information.

6. Security Considerations

The YANG module defined in this document will be accessed via the NETCONF protocol [RFC6241] or RESTCONF protocol [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS and the mandatory-to-implement secure transport is TLS [RFC8446].

The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access to particular NETCONF or RESTCONF users to a pre-configured subset of all available NETCONF or RESTCONF protocol operations and content.

Some of the RPC operations defined in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus essential to control access to these operations.

Operations defined in this document, and their sensitivities and possible vulnerabilities, will be discussed further in future versions of this document.

7. IANA Considerations

This document registers the following URIs in the "ns" subregistry within the "IETF XML registry" [RFC3688].

  URI: urn:ietf:params:xml:ns:yang:ietf-wson-path-computation
  Registrant Contact:  The IESG.
  XML: N/A, the requested URI is an XML namespace.

  URI: urn:ietf:params:xml:ns:yang:ietf-flexi-grid-path-computation
  Registrant Contact:  The IESG.
  XML: N/A, the requested URI is an XML namespace.

This document registers the following YANG module in the "YANG Module Names" registry [RFC7950].

  name:      ietf-wson-path-computation
  namespace: urn:ietf:params:xml:ns:yang:ietf-wson-path-computation
  prefix:    wson-pc
  reference: this document

  name:      ietf-flexi-grid-path-computation
  namespace: ietf:params:xml:ns:yang:ietf-flexi-grid-path-computation
  prefix:    flexg-pc
  reference: this document

8. References

8.1. Normative References

[I-D.ietf-ccamp-rfc9093-bis]
Belotti, S., Busi, I., Beller, D., Zheng, H., Le Rouzic, E., Guo, A., and D. King, "A YANG Data Model for Layer 0 Types", Work in Progress, Internet-Draft, draft-ietf-ccamp-rfc9093-bis-05, , <https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-rfc9093-bis-05>.
[I-D.ietf-teas-yang-path-computation]
Busi, I., Belotti, S., de Dios, O. G., Sharma, A., and Y. Shi, "A YANG Data Model for requesting path computation", Work in Progress, Internet-Draft, draft-ietf-teas-yang-path-computation-21, , <https://datatracker.ietf.org/doc/html/draft-ietf-teas-yang-path-computation-21>.
[I-D.ietf-teas-yang-te]
Saad, T., Gandhi, R., Liu, X., Beeram, V. P., and I. Bryskin, "A YANG Data Model for Traffic Engineering Tunnels, Label Switched Paths and Interfaces", Work in Progress, Internet-Draft, draft-ietf-teas-yang-te-34, , <https://datatracker.ietf.org/doc/html/draft-ietf-teas-yang-te-34>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[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, , <https://www.rfc-editor.org/info/rfc7699>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/info/rfc8040>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/info/rfc8341>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.

8.2. Informative References

[I-D.draft-gbb-ccamp-otn-path-computation-yang]
Busi, I., Guo, A., and S. Belotti, "A YANG Data Model for requesting Path Computation in an Optical Transport Network (OTN)", Work in Progress, Internet-Draft, draft-gbb-ccamp-otn-path-computation-yang-02, , <https://datatracker.ietf.org/doc/html/draft-gbb-ccamp-otn-path-computation-yang-02>.
[I-D.ietf-ccamp-flexigrid-tunnel-yang]
de Madrid, U. A., Burrero, D. P., King, D., Lopez, V., Busi, I., Belotti, S., and G. Galimberti, "A YANG Data Model for Flexi-Grid Tunnels", Work in Progress, Internet-Draft, draft-ietf-ccamp-flexigrid-tunnel-yang-03, , <https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-flexigrid-tunnel-yang-03>.
[I-D.ietf-ccamp-wson-tunnel-model]
Lee, Y., Zheng, H., Guo, A., Lopez, V., King, D., Yoon, B. Y., and R. Vilalta, "A Yang Data Model for WSON Tunnel", Work in Progress, Internet-Draft, draft-ietf-ccamp-wson-tunnel-model-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-wson-tunnel-model-09>.
[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-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-teas-actn-poi-applicability-09>.
[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, , <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, , <https://www.rfc-editor.org/info/rfc7581>.

Appendix A. Change Log

The initial YANG data model requesting path computation in optical networks was draft-gbb-ccamp-optical-path-computation-yang-00. This document included path computation request capabilities for WSON, Flexi-Grid and OTN technologies. However, it was proposed at IETF 113 (March 25, 2022) to split the initial document into separate documents for WDM (WSON and Flexi-Grid) and OTN technologies, as each technology may be developed and implemented separately.

The WDM technology capabilities were kept in this document, and the OTN capabilities were moved into [I-D.draft-gbb-ccamp-otn-path-computation-yang].

Editors note, please remove this appendix before publication.

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.

The authors of this document would also like to thank Young Lee, Haomian Zheng, Victor Lopex, Ricard Vilalta, Bin Yeong Yoon, Jorge E. Lopez de Vergara Mendez, Daniel Perdices Burrero, Oscar Gonzalez de Dios, Gabriele Galimberti, Zafar Ali, Daniel Michaud Vallinoto and Dhruv Dhody who have contributed to the development of path computation augmentations for WSON and Flexi-grid topology in earlier versions of [I-D.ietf-ccamp-wson-tunnel-model] and of [I-D.ietf-ccamp-flexigrid-tunnel-yang].

This document was prepared using kramdown.

Contributors

Daniel King
Old Dog Consulting

Authors' Addresses

Italo Busi
Huawei Technologies
Aihua Guo
Futurewei Technologies
Sergio Belotti
Nokia