Internet-Draft YANG Data Model for SR Policy March 2024
Raza, et al. Expires 5 September 2024 [Page]
Workgroup:
SPRING Working Group
Internet-Draft:
draft-ietf-spring-sr-policy-yang-03
Published:
Intended Status:
Standards Track
Expires:
Authors:
K. Raza, Ed.
Cisco Systems
T. Saleh
Cisco Systems
Z. Shunwan
Huawei Technologies
D. Voyer
Bell Canada
M. Durrani
Equinix
S. Matsushima
SoftBank
V. Beeram
Juniper Networks

YANG Data Model for Segment Routing Policy

Abstract

This document defines a YANG data model for Segment Routing (SR) Policy that can be used for configuring, instantiating, and managing SR policies. The model is generic and applies equally to the MPLS and SRv6 instantiations of SR policies.

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/.

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This Internet-Draft will expire on 5 September 2024.

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Table of Contents

1. Introduction

The Network Configuration Protocol (NETCONF) [RFC6241] defines mechanisms to manage network devices. YANG [RFC6020] is a modular language that represents data structures in an XML tree format, and is used as a data modeling language for NETCONF.

Segment Routing (SR), as defined in [RFC8402], allows a headend node to steer a packet flow along any topological path and/or service chain. The headend node is said to steer a flow into a Segment Routing Policy (SR Policy). An SR policy is a framework that enables instantiation of an ordered list of segments on a node for implementing a policy [RFC9256].

This document introduces a YANG data model for SR policy framework for instantiating, configuring and managing SR policies along with its attributes. It is also expected that other companion models, such as BGP SR Policy [I-D.ietf-idr-segment-routing-te-policy], will be defined and/or augmented accordingly in their respective areas.

This model defines the following constructs for managing an SR policy:

This document expects and requires the reader to be well familiar with the concepts and constructs of an SR policy [RFC9256] as well as the YANG modeling language and its presentation [RFC6020].

2. Specification of Requirements

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. Building Blocks

Before looking into the YANG model for SR policy, it is important to recall and highlight the major building blocks and constructs that constitute and contribute to an SR policy, as described in [RFC9256].

4. YANG Model

The modeling in this document complies with the Network Management Datastore Architecture (NMDA) [RFC8342]. The operational state data is combined with the associated configuration data in the same hierarchy [RFC8407]. When protocol states are retrieved from the NMDA operational state datastore, the returned states cover all "config true" (rw) and "config false" (ro) nodes defined in the schema.

For SR policy YANG specification, this document defines following new YANG modules:

Table 1
Module Name Purpose
ietf-sr-policy-types defines common and basic types related to an SR policy and related constructs
ietf-sr-policy defines the model for SR policy instantiation, configuration, and management

4.1. Types and Definitions

SR policy common types and definitions are defined in the new module "ietf-sr-policy-types". The main types defined in this module include:

The associated YANG specification for this module is captured in Section 7.1.

4.2. SR Policy

The base SR policy model is captured in ietf-sr-policy module. This base module augments "/rt:routing" and specifies the configuration, operational state, executables/rpcs, and notification events required to manage SR policies.

The associated YANG specification for this module is captured in Section 7.2.

4.2.1. Configuration

In terms of configuration hierarchy, SR policy configuration tree has following two main areas:

  • attributes: container that defines common constructs that could be used across policies. Examples of such a construct include segment-lists, affinity-map etc. In future revision of this document, it is expected that this container will have more constructs defined.

  • policies: container that defines list of policies with their attributes such as BSID, candidate-paths etc.

Following diagram depicts high level yang organization and hierarchy for an SR policy specification:

segment-routing
   traffic-engineering
      + attributes
      |   + affinity-map
      |   |  ....
      |   |
      |   + segment-lists
      |   |    segment-list* [name]
      |   |        segments
      |   |            segment* [index]
      |   |                ...
      |   + explicit-binding-sid-rules
      |        ...
      |
      + policies
           policy* [color endpoint]
              + ...
              |
              + binding-sid
              | ...
              |
              + candidate-paths
                  candidate-path* [protocol-origin originator discriminator]
                      + ...
                      |
                      + type
                          + explicit
                          |   segment-lists
                          |        segment-list* [ref]
                          |             ...
                          + dynamic
                        constraints
                                   ...
Figure 1: SR Policy - Hierarchy

The complete YANG tree can be found in Figure 3.

Please take note of the following important points regarding the configurations:

  • This model supports both MPLS and SRv6 dataplane for SR -- i.e. items like segments and BSID can be defined as MPLS label or SRv6 SIDs.

  • Specification of a segment supports all the types defined in SR policy base specification document

  • The above model supports explicit BSID specification on SR policy level as the main mode of specification. The model also allows explicit BSID per candidate-path as an if-feature capability that is optional for implementations

  • The above model will be extended in future revisions of this document to enhance constraints specification for dynamic type of candidate-path, as well as add traffic-steering controls.

4.2.2. State

As per NMDA model, the state related to configuration items specified in earlier Section 4.2.1 can be retrieved from the same tree. This section defines the other operational state items related to SR policy.

In addition to configured state, the operational state corresponding to the SR policy includes:

  • policy operational state

  • policy up/down timestamps

  • policy BSID info such as alloc mode, actual value in-use, operational state, and forwarding stats

  • Per candidate-path info such as:

    • Whether candidate-path is the best candidate-path

    • In case of non-best, the reason for such non-selection

    • Type of candidate-path - explicit or dynamic

    • Per segment-list information - such as validity of the segment-list, as well as forwarding state for a valid segment-list. The forwarding state is represented in terms of per forwarding path info that includes nexthop address, outgoing interface, protection information, and encapsulation (label stack or SRv6 SID stack) etc.

The complete YANG tree can be found in Figure 3.

4.2.3. Notification

This model defines a list of notifications to inform an operator of important events detected regarding an SR policy. These events include events related to:

  • policy status: policy operational state changes

  • Candidate-path active status and changes

  • Explicit Binding SID collision/unavailability events

Following is a simplified graphical representation of the data model for SR policy notifications:

module: ietf-sr-policy

  notifications:
    +---n sr-policy-oper-state-change-event
    |  +--ro policy-name-ref?         -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
    |  +--ro policy-color-ref?        -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
    |  +--ro policy-endpoint-ref?     -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
    |  +--ro policy-new-oper-state?   sr-policy-types:policy-oper-state
    |  +--ro policy-down-reason?      identityref
    +---n sr-policy-candidate-path-change-event
    |  +--ro policy-name-ref?       -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
    |  +--ro policy-color-ref?      -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
    |  +--ro policy-endpoint-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
    |  +--ro existing-preference?   uint32
    |  +--ro new-preference?        uint32
    +---n sr-policy-binding-sid-unavailable-event
    |  +--ro policy-name-ref?                -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
    |  +--ro policy-color-ref?               -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
    |  +--ro policy-endpoint-ref?            -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
    |  +--ro policy-binding-sid-value-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/binding-sid/value
    |  +--ro reason?                         identityref
    +---n sr-policy-candidate-path-binding-sid-mismatch-event
       +--ro policy-color-ref?                                    -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
       +--ro policy-endpoint-ref?                                 -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
       +--ro existing-candidate-path-protocol-origin-ref?         -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/protocol-origin
       +--ro existing-candidate-path-preference-ref?              -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/preference
       +--ro existing-candidate-path-binding-sid-dataplane-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/binding-sid/dataplane
       +--ro existing-candidate-path-binding-sid-value-ref?       -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/binding-sid/value
       +--ro conflicting-candidate-path-protocol-origin?          uint8
       +--ro conflicting-candidate-path-preference?               uint32
       +--ro conflicting-candidate-path-binding-sid-dataplane?    sr-policy-types:dataplane-type
       +--ro conflicting-candidate-path-binding-sid-value?        sr-policy-types:sid-value-type
Figure 2: SR Policy - Notification Tree

5. Pending Items

Following are the items that will be addressed in future revisions of this document:

6. YANG Tree

Using the building blocks described in Section 3, following is the complete graphical representation of the data model for SR policy:

module: ietf-sr-policy
augment /rt:routing:
   +--rw segment-routing
      +--rw traffic-engineering
         +--rw attributes
         |  +--rw segment-lists
         |  |  +--rw segment-list* [name]
         |  |     +--rw name        string
         |  |     +--rw segments
         |  |        +--rw segment* [index]
         |  |           +--rw index       uint32
         |  |           +--rw type        identityref
         |  |           +--rw sr-mpls
         |  |           |  +--rw Type-A
         |  |           |  |  +--rw value?   rt-types:mpls-label
         |  |           |  +--rw Type-C
         |  |           |  |  +--rw ipv4-address?   inet:ipv4-address
         |  |           |  |  +--rw algorithm?      uint8
         |  |           |  +--rw Type-D
         |  |           |  |  +--rw ipv6-address?   inet:ipv6-address
         |  |           |  |  +--rw algorithm?      uint8
         |  |           |  +--rw Type-E
         |  |           |  |  +--rw ipv4-address?           inet:ipv4-address
         |  |           |  |  +--rw interface-identifier?   uint32
         |  |           |  +--rw Type-F
         |  |           |  |  +--rw local-ipv4-address?    inet:ipv4-address
         |  |           |  |  +--rw remote-ipv4-address?   inet:ipv4-address
         |  |           |  +--rw Type-G
         |  |           |  |  +--rw local-ipv6-address?            inet:ipv6-address
         |  |           |  |  +--rw local-interface-identifier?    uint32
         |  |           |  |  +--rw remote-ipv6-address?           inet:ipv6-address
         |  |           |  |  +--rw remote-interface-identifier?   uint32
         |  |           |  +--rw Type-H
         |  |           |     +--rw local-ipv6-address?    inet:ipv6-address
         |  |           |     +--rw remote-ipv6-address?   inet:ipv6-address
         |  |           +--rw srv6
         |  |           |  +--rw Type-B
         |  |           |  |  +--rw value?           srv6-types:srv6-sid
         |  |           |  |  +--rw sid-behavior?    identityref
         |  |           |  |  +--rw sid-structure
         |  |           |  |     +--rw locator-block-length?   srv6-types:srv6-locator-block-len
         |  |           |  |     +--rw locator-node-length?    srv6-types:srv6-locator-node-len
         |  |           |  |     +--rw function-length?        srv6-types:srv6-function-len
         |  |           |  |     +--rw argument-length?        srv6-types:srv6-argument-len
         |  |           |  +--rw Type-I
         |  |           |  |  +--rw ipv6-address?   inet:ipv6-address
         |  |           |  |  +--rw algorithm?      uint8
         |  |           |  +--rw Type-J
         |  |           |  |  +--rw local-ipv6-address?            inet:ipv6-address
         |  |           |  |  +--rw local-interface-identifier?    uint32
         |  |           |  |  +--rw remote-ipv6-address?           inet:ipv6-address
         |  |           |  |  +--rw remote-interface-identifier?   uint32
         |  |           |  +--rw Type-K
         |  |           |     +--rw local-ipv6-address?    inet:ipv6-address
         |  |           |     +--rw remote-ipv6-address?   inet:ipv6-address
         |  |           +--rw validate?   boolean
         |  +--rw explicit-binding-sid-rules* [index]
         |     +--rw index    uint32
         |     +--rw rule     sr-policy-types:explicit-binding-sid-rule-type
         +--rw policies
            +--rw policy* [color endpoint]
               +--rw name?               sr-policy-types:name-type
               +--rw color               sr-policy-types:color-type
               +--rw endpoint            inet:ip-address
               +--rw description?        string
               +--rw admin-state?        sr-policy-types:policy-admin-state
               +--rw priority?           uint8
               +--ro oper-state?         sr-policy-types:policy-oper-state
               +--ro transition-count?   uint32
               +--ro up-time?            yang:date-and-time
               +--ro down-time?          yang:date-and-time
               +--rw binding-sid
               |  +--rw dataplane?       sr-policy-types:dataplane-type
               |  +--rw value?           sr-policy-types:sid-value-type
               |  +--rw srv6
               |  |  +--rw locator-name?    srv6-types:locator-name-type
               |  |  +--rw sid-behavior?    identityref
               |  |  +--rw sid-structure
               |  |     +--rw locator-block-length?   srv6-types:srv6-locator-block-len
               |  |     +--rw locator-node-length?    srv6-types:srv6-locator-node-len
               |  |     +--rw function-length?        srv6-types:srv6-function-len
               |  |     +--rw argument-length?        srv6-types:srv6-argument-len
               |  +--ro alloc-mode?      sr-policy-types:binding-sid-alloc-mode
               |  +--ro allocated-sid?   sr-policy-types:sid-value-type
               |  +--ro oper-state?      sr-policy-types:binding-sid-oper-state
               +--ro counters
               |  +--ro pkts?     yang:counter64
               |  +--ro octets?   yang:counter64
               +--rw candidate-paths
                  +--rw candidate-path* [protocol-origin originator-asn originator-node-address discriminator]
                     +--rw protocol-origin            identityref
                     +--rw originator-asn             uint32
                     +--rw originator-node-address    sr-policy-types:node-address-type
                     +--rw discriminator              uint32
                     +--rw preference                 uint32
                     +--rw name?                      string
                     +--rw description?               string
                     +--rw drop-upon-invalid?         boolean
                     +--rw admin-state?               boolean
                     +--rw binding-sid {capability-candidate-path-binding-sid}?
                     |  +--rw dataplane?   sr-policy-types:dataplane-type
                     |  +--rw value?       sr-policy-types:sid-value-type
                     |  +--rw srv6
                     |     +--rw locator-name?    srv6-types:locator-name-type
                     |     +--rw sid-behavior?    identityref
                     |     +--rw sid-structure
                     |        +--rw locator-block-length?   srv6-types:srv6-locator-block-len
                     |        +--rw locator-node-length?    srv6-types:srv6-locator-node-len
                     |        +--rw function-length?        srv6-types:srv6-function-len
                     |        +--rw argument-length?        srv6-types:srv6-argument-len
                     +--rw (type)?
                     |  +--:(explicit)
                     |  |  +--rw segment-lists
                     |  |     +--rw segment-list* [name-ref]
                     |  |        +--rw name-ref    -> /rt:routing/sr-policy:segment-routing/traffic-engineering/attributes/segment-lists/segment-list/name
                     |  |        +--rw weight?     uint32
                     |  |        +--ro is-valid?   boolean
                     |  +--:(dynamic)
                     |  |  +--rw segment-list
                     |  |  |  +--rw segment-list-dataplane-type    sr-policy-types:dataplane-type
                     |  |  |  +--ro is-valid?                      boolean
                     |  |  +--rw optimization-objectives
                     |  |  |  +--rw minimize-metric
                     |  |  |     +--rw metric-type?   sr-policy-types:metric-type
                     |  |  |     +--rw margin
                     |  |  |        +--rw type?             sr-policy-types:margin-type
                     |  |  |        +--rw value?            uint32
                     |  |  |        +--ro computed-value?   uint32
                     |  |  +--rw constraints
                     |  |     +--rw srlg
                     |  |     |  +--rw exclude-any*   string
                     |  |     |  +--rw include-any*   string
                     |  |     |  +--rw include-all*   string
                     |  |     +--rw affinity
                     |  |     |  +--rw exclude-any*   string
                     |  |     |  +--rw include-any*   string
                     |  |     |  +--rw include-all*   string
                     |  |     +--rw ip-address
                     |  |     |  +--rw exclude*       inet:ip-address
                     |  |     |  +--rw include-any*   inet:ip-address
                     |  |     |  +--rw include-all*   inet:ip-address
                     |  |     +--rw upper-bounds
                     |  |     |  +--rw cumulative-metric
                     |  |     |  |  +--rw metric-type?   sr-policy-types:metric-type
                     |  |     |  |  +--rw value?         uint32
                     |  |     |  +--rw max-sids?            uint32
                     |  |     +--rw segment-rules
                     |  |     |  +--rw sid-algorithm?                sr-policy-types:sid-algorithm-type
                     |  |     |  +--rw sid-protection-eligibility?   sr-policy-types:sid-protection-eligibility-type
                     |  |     +--rw disjoint-path
                     |  |     |  +--rw disjointness-type?         te-types:te-path-disjointness
                     |  |     |  +--rw association-group-id       uint16
                     |  |     |  +--rw association-source         inet:ip-address
                     |  |     |  +--rw association-extended-id?   yang:hex-string
                     |  |     +--rw bandwidth
                     |  |     |  +--rw requested?   uint32
                     |  |     |  +--ro reserved?    uint32
                     |  |     +--rw max-sids?        uint32
                     |  +--:(composite)
                     |     +--rw constituent-policies
                     |        +--rw constituent-policy* [color]
                     |           +--rw color     sr-policy-types:color-type
                     |           +--rw weight?   uint32
                     +--ro is-best-candidate-path?    boolean
                     +--ro non-selection-reason?      identityref
                     +--ro is-active?                 boolean
                     +--ro is-valid?                  boolean
                     +--ro forwarding-paths
                        +--ro forwarding-path* [path-id]
                           +--ro path-id              uint8
                           +--ro next-hop-address?    inet:ip-address
                           +--ro next-hop-table-id?   uint32
                           +--ro interface?           if:interface-ref
                           +--ro sid-list
                           |  +--ro (dataplanetype)?
                           |     +--:(mpls)
                           |     |  +--ro labels* [index]
                           |     |     +--ro index    uint32
                           |     |     +--ro label?   rt-types:mpls-label
                           |     +--:(srv6)
                           |        +--ro sids* [index]
                           |           +--ro index    uint32
                           |           +--ro sid?     srv6-types:srv6-sid
                           +--ro is-protected?        boolean
                           +--ro is-pure-backup?      boolean
                           +--ro backup-path-id?      uint8
                           +--ro weight?              uint32
notifications:
   +---n sr-policy-oper-state-change-event
   |  +--ro policy-name-ref?         -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
   |  +--ro policy-color-ref?        -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
   |  +--ro policy-endpoint-ref?     -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
   |  +--ro policy-new-oper-state?   sr-policy-types:policy-oper-state
   |  +--ro policy-down-reason?      identityref
   +---n sr-policy-candidate-path-change-event
   |  +--ro policy-name-ref?       -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
   |  +--ro policy-color-ref?      -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
   |  +--ro policy-endpoint-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
   |  +--ro existing-preference?   uint32
   |  +--ro new-preference?        uint32
   +---n sr-policy-binding-sid-unavailable-event
   |  +--ro policy-name-ref?                -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/name
   |  +--ro policy-color-ref?               -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
   |  +--ro policy-endpoint-ref?            -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
   |  +--ro policy-binding-sid-value-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/binding-sid/value {capability-candidate-path-binding-sid}?
   |  +--ro reason?                         identityref
   +---n sr-policy-candidate-path-binding-sid-mismatch-event
      +--ro policy-color-ref?                                    -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/color
      +--ro policy-endpoint-ref?                                 -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/endpoint
      +--ro existing-candidate-path-protocol-origin-ref?         -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/protocol-origin
      +--ro existing-candidate-path-preference-ref?              -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/preference
      +--ro existing-candidate-path-binding-sid-dataplane-ref?   -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/binding-sid/dataplane {capability-candidate-path-binding-sid}?
      +--ro existing-candidate-path-binding-sid-value-ref?       -> /rt:routing/sr-policy:segment-routing/traffic-engineering/policies/policy/candidate-paths/candidate-path/binding-sid/value {capability-candidate-path-binding-sid}?
      +--ro conflicting-candidate-path-protocol-origin?          uint8
      +--ro conflicting-candidate-path-preference?               uint32
      +--ro conflicting-candidate-path-binding-sid-dataplane?    sr-policy-types:dataplane-type
      +--ro conflicting-candidate-path-binding-sid-value?        sr-policy-types:sid-value-type
Figure 3: SR Policy - YANG Tree

7. YANG Specification

Following are actual YANG definition for the modules defined earlier in the document.

7.1. Types 

<CODE BEGINS> file "ietf-sr-policy-types@2024-03-04.yang"

module ietf-sr-policy-types {
  namespace "urn:ietf:params:xml:ns:yang:ietf-sr-policy-types";

  prefix "sr-policy-types";

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

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

  import ietf-srv6-types {
    prefix "srv6-types";
  }

  organization "IETF SPRING Working Group";

  contact
      "WG Web:   <http://tools.ietf.org/wg/spring/>
       WG List:  <mailto:spring@ietf.org>
       Editor:   Kamran Raza
                 <mailto:skraza@cisco.com>
       Editor:   Robert Sawaya
                 <mailto:rsawaya@cisco.com>
       Editor:   Zhuang Shunwan
                 <mailto:zhuangshunwa@huawei.com>
       Editor:   Daniel Voyer
                 <mailto:daniel.voyer@bell.ca>
       Editor:   Muhammad Durrani
                 <mailto:mdurrani@equinix.com>
       Editor:   Satoru Matsushima
                 <mailto:satoru.matsushima@g.softbank.co.jp>
       Editor:   Pavan Vishnu Beeram
                 <mailto:vbeeram@juniper.net>
       ";

  description
    "This YANG module defines the essential types for the management
     of SR policy module.
     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 Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

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

    // RFC Editor: replace XXXX with actual RFC number and remove
    // this note

  revision 2024-03-04 {
    // RFC Editor: replace the above date 2024-03-04 with the date of
    // publication and remove this note.

    description
      "Alignment with SR policy architecture RFC9256";
    reference
      "RFC XXXX: YANG Data Model for Segment-routing Policy Types";
     // RFC Editor: replace XXXX with actual RFC number and remove
     // this note
  }

  revision "2022-03-28" {
    description
      "Alignment with SR policy architecture";
    reference
      "draft-ietf-spring-sr-policy-yang";
  }

  revision "2019-11-04" {
    description
      "New editor added";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  revision "2019-07-08" {
    description
      "Dynamic TE candidate-path support";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  revision "2018-07-01" {
    description
      "Initial version";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  /* Identities */
  identity candidate-path-not-selected-reason {
    description
      "Base identity for which reasons for not selecting
      candidate path are derived from";
  }
  identity candidate-path-not-selected-not-best {
    base candidate-path-not-selected-reason;
    description
      "Higher preference path exists";
  }
  identity candidate-path-not-selected-no-valid-segment-list {
    base candidate-path-not-selected-reason;
    description
      "Candidate path has no valid segment list(s)";
  }
  identity candidate-path-not-selected-empty-segment-list {
    base candidate-path-not-selected-reason;
    description
      "Candidate path has empty segment list(s)";
  }
  identity candidate-path-not-selected-invalid-binding-sid {
    base candidate-path-not-selected-reason;
    description
      "Candidate path has invalid binding SID";
  }

  identity policy-down-reason {
   description
      "Base identity for the reasons why SR policy is operationally
      down";
  }
  identity policy-down-reason-admin-down {
    base policy-down-reason;
    description "Policy is administrately down";
  }
  identity policy-down-reason-no-source-address {
    base policy-down-reason;
    description "Policy has no source address";
  }
  identity policy-down-reason-no-endpoint {
    base policy-down-reason;
    description "Policy has no end-point";
  }
  identity policy-down-reason-no-candidate-path {
    base policy-down-reason;
    description "Policy has no candidate path";
  }
  identity policy-down-reason-no-valid-candidate-path {
    base policy-down-reason;
    description "Policy has no valid candidate path";
  }
  identity policy-down-reason-candidate-path-invalid-segment-list {
    base policy-down-reason;
    description "Policy's candidate path has invalid segment list";
  }
  identity policy-down-reason-policy-unconfigured {
    base policy-down-reason;
    description "Policy is unconfigured";
  }
  identity policy-down-reason-policy-color-endpoint-updated {
    base policy-down-reason;
    description "Policy's color and end-point are updated";
  }
  identity policy-down-reason-local-label-setup-failed {
    base policy-down-reason;
    description "Policy's local label setup (allocation/rewrite)
    failed";
  }
  identity policy-down-reason-forwarding-rewrite-failed {
    base policy-down-reason;
    description "Policy's forwarding rewrite installation failed";
  }
  identity policy-down-reason-internal-error {
    base policy-down-reason;
    description "Infra related internal error";
  }

  identity binding-sid-unavailable-reason {
    description
      "Base identity for binding sid unavailable reason types";
  }
  identity binding-sid-allocation-error {
    base binding-sid-unavailable-reason;
    description "SID allocator returned an error";
  }
  identity binding-sid-already-exists {
    base binding-sid-unavailable-reason;
    description "Binding sid already exists/allocated";
  }
  identity binding-sid-internal-error {
    base binding-sid-unavailable-reason;
    description "Internal error with binding sid allocation";
  }
  identity binding-sid-color-endpoint-conflict {
    base binding-sid-unavailable-reason;
    description "Binding sid already allocated by another sr-policy
    with different color/endpoint";
  }
  identity binding-sid-rewrite-error {
    base binding-sid-unavailable-reason;
    description "Binding sid forwarding rewrite error";
  }
  identity binding-sid-outside-srlb-range {
    base binding-sid-unavailable-reason;
    description "Binding sid outside SRLB range";
  }

  identity segment-type {
    description
      "Base identity for the segment type";
  }
  identity segment-type-A {
    base segment-type;
    description "SR-MPLS Label";
  }
  identity segment-type-B {
    base segment-type;
    description "SRv6 SID";
  }
  identity segment-type-C {
    base segment-type;
    description "IPv4 Prefix with optional SR Algorithm";
  }
  identity segment-type-D {
    base segment-type;
    description "IPv6 Global Prefix with optional SR Algorithm for
    SR-MPLS";
  }
  identity segment-type-E {
    base segment-type;
    description "IPv4 Prefix with Local Interface ID";
  }
  identity segment-type-F {
    base segment-type;
    description "IPv4 Addresses for link endpoints as Local,
    Remote pair";
  }
  identity segment-type-G {
    base segment-type;
    description
      "IPv6 Prefix and Interface ID for link endpoints as Local,
      Remote pair for SR-MPLS";
  }
  identity segment-type-H {
    base segment-type;
    description
      "IPv6 Addresses for link endpoints as Local,
      Remote pair for SR-MPLS";
  }
  identity segment-type-I {
    base segment-type;
    description
      "IPv6 Global Prefix with optional SR Algorithm for SRv6";
  }
  identity segment-type-J {
    base segment-type;
    description
      "IPv6 Prefix and Interface ID for link endpoints as Local,
      Remote pair for SRv6";
  }
  identity segment-type-K {
    base segment-type;
    description
      "IPv6 Addresses for link endpoints as Local, Remote pair for
      SRv6";
  }

  identity protocol-origin-type {
    description "Base identity for originating protocol type";
  }
  identity protocol-origin-type-pcep {
    base protocol-origin-type;
    description
      "PCEP used as signalling mechanism for the candidate path";
  }
  identity protocol-origin-type-bgp {
    base protocol-origin-type;
    description
      "BGP used as signalling mechanism for the candidate path";
  }
  identity protocol-origin-type-local {
    base protocol-origin-type;
    description
      "CLI, Yang model via Netconf, gRPC, etc used for candidate path
      instantiation";
  }

  /* Typdefs */
  typedef sid-value-type {
    type union {
      type rt-types:mpls-label;
      type srv6-types:srv6-sid;
    }
    description "The SID value type";
  }

  typedef binding-sid-oper-state {
    type enumeration {
      enum ALLOC-PENDING {
        value 1;
        description "SID allocation pending for Binding SID";
      }
      enum PROGRAMMED {
        value 3;
        description "Binding SID is programmed in forwarding";
      }
      enum CONFLICT {
        value 4;
        description "Binding SID is in-conflict state with
        regards to SID allocation. This also means that SID
        allocation is pending";
      }
    }
    description
      "Binding SID operational state type";
  }

  typedef policy-admin-state {
    type enumeration {
      enum UP {
        value 1;
        description "SR policy is administratively up";
      }
      enum DOWN {
        value 2;
        description "SR policy is administratively down";
      }
    }
    description "SR policy admin state";
  }

  typedef policy-oper-state {
    type enumeration {
      enum UP {
        value 1;
        description "SR policy is operationally up";
      }
      enum DOWN {
        value 2;
        description "SR policy is operationally down";
      }
    }
    description "SR policy oper state";
  }

  typedef metric-type {
    type enumeration {
      enum te { value 1; description "TE metric"; }
      enum igp { value 2; description "IGP metric"; }
      enum latency { value 3; description "Latency metric"; }
    }
    description "Metric type";
  }

  typedef margin-type {
    type enumeration {
      enum absolute { value 1; description "Absolute value"; }
      enum relative { value 2; description "Relative value"; }
    }
    description "Margin type";
  }

  typedef dataplane-type {
    type enumeration {
      enum mpls {
        value 1;
        description "Segment-routing MPLS";
      }
      enum srv6 {
        value 2;
        description "Segment-routing v6";
      }
    }
    description "Dataplane type of the segments";
  }

  typedef binding-sid-alloc-mode {
    type enumeration {
      enum explicit {
        value 1;
        description "Explicitly specified BSID";
      }
      enum dynamic {
        value 2;
        description "Dynamically allocated BSID";
      }
    }
    description "binding SID allocation mode";
  }

  typedef explicit-binding-sid-rule-type {
    type enumeration {
      enum enforce-srlb {
        value 1;
        description
            "Explicit Binding SID is enforced with no
             fallback if label does not fall in SRLB or
             if no SRLB is configured";
      }
      enum fallback-dynamic {
        value 2;
        description
            "Explicit Binding SID falls back to dynamic in
            case explicit label is not available.";
      }
    }
    description "Explicit binding sid rule types";
  }

  typedef sid-protection-eligibility-type {
    type enumeration {
      enum protected-preferred {
        value 1;
        description "Prefer protected SID";
      }
      enum protected-only {
        value 2;
        description "Protected SID only";
      }
      enum unprotected-preferred {
        value 3;
        description "Prefer unprotected SID";
      }
      enum unprotected-only {
        value 4;
        description "Unprotected SID only";
      }
    }
    description "Types for SID protection eligibility";
  }

  typedef node-address-type {
    type inet:ipv6-address;
    description "Originator node address";
  }

  typedef sid-algorithm-type {
      type uint8 {
        range "0..255";
      }
    description "SID algorithm type";
  }

  typedef color-type {
    type uint32 {
      range "1..4294967295";
    }
    description "SID algorithm type";
  }

  typedef name-type {
    type string {
      length "1..59";
    }
    description "Policy name type";
  }
}

<CODE ENDS>
Figure 4: ietf-sr-policy-types.yang

7.2. SR Policy 

<CODE BEGINS> file "ietf-sr-policy@2024-03-04.yang"

module ietf-sr-policy {

  namespace "urn:ietf:params:xml:ns:yang:ietf-sr-policy";

  prefix "sr-policy";

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

  import ietf-interfaces {
    prefix if;
  }

  import ietf-routing {
    prefix "rt";
  }

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

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

  import ietf-srv6-types {
    prefix "srv6-types";
  }

  import ietf-sr-policy-types {
    prefix "sr-policy-types";
  }

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

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

    Editor:   Kamran Raza
    <mailto:skraza@cisco.com>

    Editor:   Robert Sawaya
    <mailto:rsawaya@cisco.com>

    Editor:   Zhuang Shunwan
    <mailto:zhuangshunwa@huawei.com>

    Editor:   Daniel Voyer
    <mailto:daniel.voyer@bell.ca>

    Editor:   Muhammad Durrani
    <mailto:mdurrani@equinix.com>

    Editor:   Satoru Matsushima
    <mailto:satoru.matsushima@g.softbank.co.jp>

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

  description
    "This module contains a collection of YANG definitions
    for SR policy module.

    Copyright (c) 2019 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
    (http://trustee.ietf.org/license-info).

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

    // RFC Editor: replace XXXX with actual RFC number and remove
    // this note

  revision 2024-03-04 {
    // RFC Editor: replace the above date 2024-03-04 with the date of
    // publication and remove this note.

    description
      "Alignment with SR policy architecture RFC9256";
    reference
      "RFC XXXX: YANG Data Model for Segment-routing Policy";
     // RFC Editor: replace XXXX with actual RFC number and remove
     // this note
  }

  revision "2022-03-28" {
    description
      "Alignment with SR policy architecture";
    reference
      "draft-ietf-spring-sr-policy-yang";
  }

  revision "2019-11-04" {
    description
      "Changes in keys for policy and its candidate paths";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  revision "2019-07-08" {
    description
      "Dynamic TE candidate-path support";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  revision "2018-07-01" {
    description
      "Initial version";
    reference
      "draft-raza-spring-sr-policy-yang";
  }

  // TODO: Move this grouping to ietf-srv6-types
  grouping srv6-sid-structure {
    description "SRv6 SID structure grouping";

    leaf locator-block-length {
      type srv6-types:srv6-locator-block-len;
      description "SRv6 SID locator block length in bits";
    }
    leaf locator-node-length {
      type srv6-types:srv6-locator-node-len;
      description "SRv6 SID locator node length in bits";
    }
    leaf function-length {
      type srv6-types:srv6-function-len;
      description "SRv6 SID function length in bits";
    }
    leaf argument-length {
      type srv6-types:srv6-argument-len;
      description "SRv6 SID argument length in bits";
    }
  }

  grouping srv6-sid-type-b-config {
    description "SRv6 SID Type-B config grouping";

    leaf sid-behavior {
      type identityref {
        base srv6-types:srv6-endpoint-type;
      }
      description "SRv6 SID behavior";
    }

    container sid-structure {
      description "SRv6 SID structure";
      uses srv6-sid-structure;
      // uses srv6-types:srv6-sid-structure;
    }
  }

  grouping segment_config {
    description "Segment properties grouping";
    leaf index {
      type uint32;
      description "Segment index";
    }
    leaf type {
      type identityref {
        base sr-policy-types:segment-type;
      }
      mandatory true;
      description "Segment type";
    }

    container sr-mpls {
      description "SR-MPLS specific types";

      container Type-A {
        description
          "Segment declared by MPLS label";
        leaf value {
          type rt-types:mpls-label;
          description "MPLS label value";
        }
      }

      container Type-C {
        description
          "Segment declared by IPv4 Prefix with optional SR Algorithm
          for SR-MPLS";
        leaf ipv4-address {
          type inet:ipv4-address;
          description "Segment IPv4 address";
        }
        leaf algorithm {
          type uint8;
          description "Prefix SID algorithm identifier";
        }
      }

      container Type-D {
        description
          "Segment declared by IPv6 Global Prefix with optional
          SR Algorithm for SR-MPLS";
        leaf ipv6-address {
          type inet:ipv6-address;
          description "Segment IPv6 address";
        }
        leaf algorithm {
          type uint8;
          description "Prefix SID algorithm identifier";
        }
      }

      container Type-E {
        description
          "Segment declared by IPv4 Prefix with Local Interface ID -
          SR-MPLS";
        leaf ipv4-address {
          type inet:ipv4-address;
          description "Node IPv4 address";
        }
        leaf interface-identifier {
          type uint32;
          description "local interface identifier";
        }
      }

      container Type-F {
        description
          "Segment declared by IPv4 Addresses for link endpoints
          as Local, Remote pair - SR-MPLS";
        leaf local-ipv4-address {
          type inet:ipv4-address;
          description "Segment local IPv4 adjacency address";
        }
        leaf remote-ipv4-address {
          type inet:ipv4-address;
          description "Segment remote IPv4 adjacency address";
        }
      }

      container Type-G {
        description
          "Segment declared by IPv6 Prefix and Interface ID for
          link endpoints as Local, Remote pair for SR-MPLS";
        leaf local-ipv6-address {
          type inet:ipv6-address;
          description "Local link IPv6 address";
        }
        leaf local-interface-identifier {
          type uint32;
          description "Local interface identifier";
        }
        leaf remote-ipv6-address {
          type inet:ipv6-address;
          description "Remote link IPv6 address";
        }
        leaf remote-interface-identifier {
          type uint32;
          description "Remote interface identifier";
        }
      }

      container Type-H {
        description
          "Segment declared by IPv6 Addresses for link endpoints as
          Local, Remote pair for SR-MPLS";
        leaf local-ipv6-address {
          type inet:ipv6-address;
          description "Segment local IPv6 adjacency address";
        }
        leaf remote-ipv6-address {
          type inet:ipv6-address;
          description "Segment remote IPv6 adjacency address";
        }
      }
    } // sr-mpls

    container srv6 {
      description "SRv6 specific types";

      container Type-B {
        description
          "Segment declared by SRv6 SID value";
        leaf value {
          type srv6-types:srv6-sid;
          description "SRv6 SID value";
        }

        // TODO FIX: uses srv6-types:srv6-sid-type-b-config;
      }

      container Type-I {
        description
          "Segment declared by IPv6 Global Prefix with optional
          SR Algorithm for SRv6";
        leaf ipv6-address {
          type inet:ipv6-address;
          description "Segment IPv6 prefix";
        }
        leaf algorithm {
          type uint8;
          description "Prefix SID algorithm identifier";
        }
      }
      container Type-J {
        description
          "Segment declared by IPv6 Prefix and Interface ID for
          link endpoints as Local, Remote pair for SRv6";
        leaf local-ipv6-address {
          type inet:ipv6-address;
          description "Local link IPv6 address";
        }
        leaf local-interface-identifier {
          type uint32;
          description "Local interface identifier";
        }
        leaf remote-ipv6-address {
          type inet:ipv6-address;
          description "Remote link IPv6 address";
        }
        leaf remote-interface-identifier {
          type uint32;
          description "Remote interface identifier";
        }
      }
      container Type-K {
        description
          "Segment declared by IPv6 Addresses for link endpoints as
          Local, Remote pair for SRv6";
        leaf local-ipv6-address {
          type inet:ipv6-address;
          description "Segment local IPv6 adjacency address";
        }
        leaf remote-ipv6-address {
          type inet:ipv6-address;
          description "Segment remote IPv6 adjacency address";
        }
      }
    } // srv6

    leaf validate {
      type boolean;
      default 'false';
      description
        "Indicates whether the segment should be validated.
        The default applies to all segments other than the first
        segment. For the first segment, validation is always done.";
    }
  }

  grouping segment-properties {
    description
      "SR segment properties grouping";
    uses segment_config;
  }

  grouping attributes {
    description
      "Grouping containing attributes applicable to all SR policies";

    container attributes {
      description
        "Attributes applicable to SR policies";

      /*      uses srlg;
              uses affinity-mapping;
       */ // TODO: Beyond the scope of this model
      uses segment-lists;
      uses explicit-binding-sid-rules;
    }
  }

  grouping segment-lists {
    description
      "Segment lists grouping";
    container segment-lists {
      description "Segment-lists properties";

      list segment-list {
        key "name";
        description "Segment-list properties";
        leaf name {
          type string;
          description "Segment-list name";
        }
        container segments {
          description
            "Segments for given segment list";

          list segment {
            key "index";
            description "Configure Segment/hop at the index";
            uses segment-properties;
          }
        }
      }
    }
  }

  grouping binding-sid_config {
    description
      "Binding SID configuration properties grouping";
    leaf dataplane {
      type sr-policy-types:dataplane-type;
      description "Binding SID dataplane type";
    }
    leaf value {
      type sr-policy-types:sid-value-type;
      description "Binding SID value";
    }

    container srv6 {
      description "SRv6 BSID";

      leaf locator-name {
        type string;
        // type srv6-types:locator-name-type;
        description "Locator name used to allocate SRv6 binding SID";
      }
      uses srv6-types:srv6-sid-type-b-config;
    }
  }

  grouping forwarding-counters {
    description
      "Grouping for counters";
    container counters {
      config false;
      description
        "Counters containing stats related to forwarding";

      leaf pkts {
        type yang:counter64;
        description "Number of packets forwarded";
      }
      leaf octets {
        type yang:counter64;
        units "byte";
        description "Number of bytes forwarded";
      }
    }
  }

  grouping binding-sid_state {
    description
      "Binding SID state properties grouping";
    leaf alloc-mode {
      type sr-policy-types:binding-sid-alloc-mode;
      config false;
      description "Binding SID type";
    }
    leaf allocated-sid {
      type sr-policy-types:sid-value-type;
      config false;
      description "Allocated SID value for the Binding SID";
    }
    leaf oper-state {
      type sr-policy-types:binding-sid-oper-state;
      config false;
      description
        "Binding SID operational state";
    }
  }

  grouping binding-sid-properties {
    description
      "Binding SID properties grouping";
    container binding-sid {
      description "Binding Segment ID";
      uses binding-sid_config;
      uses binding-sid_state;
    }
  }

  grouping mpls-label-stack {
    description
      "Grouping for MPLS label stack";

    list labels {
      key "index";
      description
        "Stack containing MPLS labels";

      leaf index {
        type uint32;
        description "A unique ID of an MPLS label in labels list";
      }
      leaf label {
        type rt-types:mpls-label;
        description
          "MPLS label value";
      }
    }
  }

  grouping srv6-sid-stack {
    description
      "Grouping for SRv6 label stack";

    list sids {
      key "index";
      description
        "Stack containing SRv6 SIDs";

      leaf index {
        type uint32;
        description "A unique ID of an SRv6 sid in sid list";
      }
      leaf sid {
        type srv6-types:srv6-sid;
        description
          "SRv6 sid value";
      }
    }
  }

  grouping path-forwarding_state {
    description "Policy Forwarding path information";
    leaf path-id {
      type uint8;
      description "Primary path id";
    }
    leaf next-hop-address {
      type inet:ip-address;
      description "Nexthop address";
    }
    leaf next-hop-table-id {
      type uint32;
      description "Table ID for nexthop address";
    }
    leaf interface {
      type if:interface-ref;
      description "Outgoing interface handle";
    }
    container sid-list {
      description
        "Outgoing sid stack";
      choice dataplanetype {
        description
          "Outgoing sids dataplane choice";
        case mpls {
          uses mpls-label-stack;
        }
        case srv6 {
          uses srv6-sid-stack;
        }
      }
    }
    leaf is-protected {
      type boolean;
      description "Is this path protected ?";
    }
    leaf is-pure-backup {
      type boolean;
      description "Is this path a pure backup ?";
    }
    leaf backup-path-id {
      type uint8;
      description "Backup path id";
    }
    leaf weight {
      type uint32;
      description "Path's weight for W-ECMP balancing";
    }
  }

  grouping cpath-cmn-properties {
    description
      "Common properties of the candidate path";

    leaf is-active {
      type boolean;
      config false;
      description
        "True if the candidate path is valid and used to forward
        traffic, False otherwise";
    }

    leaf is-valid {
      type boolean;
      config false;
      description
        "True if at least one segment-list is valid,
        False otherwise";
    }

    container forwarding-paths {
      config false;
      description
        "Forwarding state of paths";
      list forwarding-path {
        key "path-id";
        description "Forwarding path";
        uses path-forwarding_state;
      }
    }
  }

  grouping explicit-path-properties {
    description
      "Explicit path properties of the candidate path";
    container segment-lists {
      description
        "Path segment list(s) properties";
      list segment-list {
        key "name-ref";
        description "SR policy candidate path segment lists";

        leaf name-ref {
          type leafref {
            path "/rt:routing/"
              + "sr-policy:segment-routing/"
              + "sr-policy:traffic-engineering/"
              + "sr-policy:attributes/"
              + "sr-policy:segment-lists/"
              + "sr-policy:segment-list/"
              + "sr-policy:name";
          }
          description "Reference to segment-list name";
        }
        leaf weight {
          type uint32;
          default 1;
          description "Segment-list weighted loadshare";
        }
        leaf is-valid {
          type boolean;
          config false;
          description
            "True if the segment-list is valid, False otherwise";
        }
      }
    }
  }

  grouping affinity-mapping {
    description "Affinity-map grouping";

    container affinity-map {
      description
        "Mapping of affinity names to bit position";
      list affinity {
        key "name";
        unique "bit-position";
        leaf name {
          type string;
          description
            "Name of the affinity";
        }
        leaf bit-position {
          type uint16;
          description
            "The affinity entry in this list is mapped to the this
            bit-position in the affinity bitmap";
        }

        description "Affinity";
      }
    }
  }

  grouping srlg {
    description "SRLG grouping";

    container srlgs {
      description "SRLG";
      list srlg {
        key "name";

        leaf name {
          type string;
          description
            "Name of the SRLG";
        }

        leaf description {
          type string;
          description
            "Description of the SRLG";
        }
        leaf value {
          type uint32;
          mandatory true;
          description
            "The associated value (for advertisements etc.) ";
        }

        description "SRLG";
      }
    }
  }

  grouping cpath-optimization-objs {
    description "Candidate-path optimization objective grouping";

    container optimization-objectives {
      description
        "Optimization objectives for the dynamic path computation";
      container minimize-metric {
        description "The metric for which the path is optimized";
        leaf metric-type {
          type sr-policy-types:metric-type;
          description "Metric type";
        }

        container margin {
          description
            "The margin by which two paths with similar metric-type
            would be considered equal";
          leaf type {
            type sr-policy-types:margin-type;
            description "Margin type";
          }
          leaf value {
            type uint32;
            description "Margin value";
          }
          leaf computed-value {
            config false;BSID";

      leaf locator-name {
        type string;
        // type srv6-types:locator-name-type;
        description "Locator name used to allocate SRv6 binding SID";
      }
      uses srv6-types:srv6-sid-type-b-config;
    }
  }

  grouping forwarding-counters {
    description
      "Grouping for counters";
    container counters {
      config false;
      description
        "Counters containing stats related to forwarding";

      leaf pkts {
        type yang:counter64;
        description "Number of packets forwarded";
      }
      leaf octets {
        type yang:counter64;
        units "byte";
        description "Number of bytes forwarded";
      }
    }
  }

  grouping binding-sid_state {
    description
      "Binding SID state properties grouping";
    leaf alloc-mode {
      type sr-policy-types:binding-sid-alloc-mode;
      config false;
      description "Binding SID type";
    }
    leaf allocated-sid {
      type sr-policy-types:sid-value-type;
      config false;
      description "Allocated SID value for the Binding SID";
    }
    leaf oper-state {
      type sr-policy-types:binding-sid-oper-state;
      config false;
      description
        "Binding SID operational state";
    }
  }

  grouping binding-sid-properties {
    description
      "Binding SID properties grouping";
    container binding-sid {
      description "Binding Segment ID";
      uses binding-sid_config;
      uses binding-sid_state;
    }
  }

  grouping mpls-label-stack {
    description
      "Grouping for MPLS label stack";

    list labels {
      key "index";
      description
        "Stack containing MPLS labels";

      leaf index {
        type uint32;
        description "A unique ID of an MPLS label in labels list";
      }
      leaf label {
        type rt-types:mpls-label;
        description
          "MPLS label value";
      }
    }
  }

  grouping srv6-sid-stack {
    description
      "Grouping for SRv6 label stack";

    list sids {
      key "index";
      description
        "Stack containing SRv6 SIDs";

      leaf index {
        type uint32;
        description "A unique ID of an SRv6 sid in sid list";
      }
      leaf sid {
        type srv6-types:srv6-sid;
        description
          "SRv6 sid value";
      }
    }
  }

  grouping path-forwarding_state {
    description "Policy Forwarding path information";
    leaf path-id {
      type uint8;
      description "Primary path id";
    }
    leaf next-hop-address {
      type inet:ip-address;
      description "Nexthop address";
    }
    leaf next-hop-table-id {
      type uint32;
      description "Table ID for nexthop address";
    }
    leaf interface {
      type if:interface-ref;
      description "Outgoing interface handle";
    }
    container sid-list {
      description
        "Outgoing sid stack";
      choice dataplanetype {
        description
          "Outgoing sids dataplane choice";
        case mpls {
          uses mpls-label-stack;
        }
        case srv6 {
          uses srv6-sid-stack;
        }
      }
    }
    leaf is-protected {
      type boolean;
      description "Is this path protected ?";
    }
    leaf is-pure-backup {
      type boolean;
      description "Is this path a pure backup ?";
    }
    leaf backup-path-id {
      type uint8;
      description "Backup path id";
    }
    leaf weight {
      type uint32;
      description "Path's weight for W-ECMP balancing";
    }
  }

  grouping cpath-cmn-properties {
    description
      "Common properties of the candidate path";

    leaf is-active {
      type boolean;
      config false;
      description
        "True if the candidate path is valid and used to forward
        traffic, False otherwise";
    }

    leaf is-valid {
      type boolean;
      config false;
      description
        "True if at least one segment-list is valid,
        False otherwise";
    }

    container forwarding-paths {
     description
        "Forwarding state of paths";

      config false;

      list forwarding-path {
        key "path-id";
        description "Forwarding path";
        uses path-forwarding_state;
      }
    }
  }

  grouping explicit-path-properties {
    description
      "Explicit path properties of the candidate path";
    container segment-lists {
      description
        "Path segment list(s) properties";
      list segment-list {
        key "name-ref";
        description "SR policy candidate path segment lists";

        leaf name-ref {
          type leafref {
            path "/rt:routing/"
              + "sr-policy:segment-routing/"
              + "sr-policy:traffic-engineering/"
              + "sr-policy:attributes/"
              + "sr-policy:segment-lists/"
              + "sr-policy:segment-list/"
              + "sr-policy:name";
          }
          description "Reference to segment-list name";
        }
        leaf weight {
          type uint32;
          default 1;
          description "Segment-list weighted loadshare";
        }
        leaf is-valid {
          type boolean;
          config false;
          description
            "True if the segment-list is valid, False otherwise";
        }
      }
    }
  }

  grouping affinity-mapping {
    description "Affinity-map grouping";

    container affinity-map {
      description
        "Mapping of affinity names to bit position";
      list affinity {
        key "name";
        unique "bit-position";
        leaf name {
          type string;
          description
            "Name of the affinity";
        }
        leaf bit-position {
          type uint16;
          description
            "The affinity entry in this list is mapped to the this
            bit-position in the affinity bitmap";
        }

        description "Affinity";
      }
    }
  }

  grouping srlg {
    description "SRLG grouping";

    container srlgs {
      description "SRLG";
      list srlg {
        key "name";

        leaf name {
          type string;
          description
            "Name of the SRLG";
        }

        leaf description {
          type string;
          description
            "Description of the SRLG";
        }
        leaf value {
          type uint32;
          mandatory true;
          description
            "The associated value (for advertisements etc.) ";
        }

        description "SRLG";
      }
    }
  }

  grouping cpath-optimization-objs {
    description "Candidate-path optimization objective grouping";

    container optimization-objectives {
      description
        "Optimization objectives for the dynamic path computation";
      container minimize-metric {
        description "The metric for which the path is optimized";
        leaf metric-type {
          type sr-policy-types:metric-type;
          description "Metric type";
        }

        container margin {
          description
            "The margin by which two paths with similar metric-type
            would be considered equal";
          leaf type {
            type sr-policy-types:margin-type;
            description "Margin type";
          }
          leaf value {
            type uint32;
            description "Margin value";
          }
          leaf computed-value {
            type uint32;
            config false;
            description "Computed metric value";
          }
        }
      }
    }
  }

  grouping cpath-constraints {
    description "Candidate-path constraints grouping";

    container constraints {
      description "Constraints for the dynamic path computation";

      container srlg { // the rule applies per link
        description "SRLG constraints on the computed dynamic path";

        leaf-list exclude-any {
          type string;
          description
            "The link is excluded if it has any of these SRLG.";
        }
        leaf-list include-any {
          type string;
          description
            "The link is accepted if it has any of these SRLG";
        }

        leaf-list include-all {
          type string;
          description
            "The link is accepted if it has all these SRLG";
        }
      }

      container affinity {  // the rule applies per link
        description
          "Affinity constraints on the computed dynamic path";

        leaf-list exclude-any {
          type string;
          description
            "The link is excluded if it has any of these affinities."
            ;
        }

        leaf-list include-any {
          type string;
          description
            "The link is accepted if it has any of these affinities";
        }
        leaf-list include-all {
          type string;
          description
            "The link is accepted if it has all these affinities";
        }
      }

      container ip-address {
        // the rule applies to e2e path and not per link
        description
          "IP address constraints on the computed dynamic path";

        leaf-list exclude {
          type inet:ip-address;
          description
            "Must exclude the links that has any of these IP
            addresses.";
        }
        leaf-list include-any {
          type inet:ip-address;
          description
            "Must include atleast 1 link (or possibly more) with any
            of these IP addresses.";
        }
        leaf-list include-all {
          type inet:ip-address;
          description
            "Must include all the links that have any of these IP
            addresses.";
        }
      }

      container upper-bounds {
        description
          "Upper-bound constraints on the computed dynamic path";

        container cumulative-metric {
          description
            "Path is invalid if its metric exceeds this value";

          leaf metric-type {
            type sr-policy-types:metric-type;
            description "Metric type";
          }

          leaf value { type uint32; description "Cumulative value"; }
        }

        leaf max-sids {
          type uint32;
          description
            "Path is invalid if it has more SIDs than this value";
        }
      }

      container segment-rules {
        description
          "Constraints on the segments to be used in the path";
        leaf sid-algorithm {
          type sr-policy-types:sid-algorithm-type;
          description
            "The prefix-sid algorithm to be used in

            path calculation";
        }

        leaf sid-protection-eligibility {
          // currently applies to adj-sid segments only
          type sr-policy-types:sid-protection-eligibility-type;
          description "SID protection eligibility";
        }
      }

      container disjoint-path {
        description "Path disjointness constraints";

        leaf disjointness-type {
          type te-types:te-path-disjointness;
          description
            "Type of disjointness computation used to find the path";
        }

        leaf association-group-id {
          type uint16;
          mandatory true;
          description "Association group Id";
        }

        leaf association-source {
          type inet:ip-address;
          mandatory true;
          description "Association source address";
        }

        leaf association-extended-id {
          type yang:hex-string;
          description
            "Association extended identifier.";
          reference
            "RFC6780";
        }
      }

      container bandwidth {
        description "Bandwidth constraints";

        leaf requested {
          type uint32;
          description
            "Requested bandwidth expressed in bytes per second";
        }
        leaf reserved {
          config false;
          type uint32;
          description
            "Reserved bandwidth expressed in bytes per second";
        }
      }

      leaf max-sids {
        type uint32;
        description "Maximum number of SIDs in a segment-list";
      }
    }
  }

  grouping dynamic-path-properties {
    description
      "Dynamic path properties of the candidate path";
    container segment-list {
      leaf segment-list-dataplane-type {
        type sr-policy-types:dataplane-type;
        mandatory true;
        description
          "The dataplane type for the segment-list";
      }
      leaf is-valid {
        type boolean;
        config false;
        description
          "True if the segment-list is valid, False otherwise";
      }
    }

    uses cpath-optimization-objs;
    uses cpath-constraints;
  }

  grouping composite-path-properties {
    description
      "Composite path properties of the candidate path";

    container constituent-policies {
      description "Constituent SR policies";

      list constituent-policy {
        key "color";
        description "List of constituent SR policies";

        leaf color {
          type sr-policy-types:color-type;
          description
            "Color associated with the constituent policy
            (the endpoint is same as the parent policy)";
        }
        leaf weight {
          type uint32;
          default 1;
          description "Constituent policy weighted loadshare";
        }
      }
    }
  }

  grouping candidate-path_state {
    description
      "Candidate path state properties grouping";
    leaf is-best-candidate-path {
      type boolean;
      default 'false';
      config false;
      description
        "True if the candidate path is the best candidate path,
        False otherwise";
    }
    leaf non-selection-reason {
      type identityref {
        base sr-policy-types:candidate-path-not-selected-reason;
      }
      config false;
      description
        "Candidate path not selected reason";
    }
  }

  grouping policy-properties_config {
    description
      "SR policy configuration grouping";
    leaf name {
      type sr-policy-types:name-type;
      description "SR policy name";
    }
    leaf color {
      type sr-policy-types:color-type;
      description "Color associated with the policy";
    }
    leaf endpoint {
      type inet:ip-address;
      description "Policy end point IP address";
    }
    leaf description {
      type string;
      description "Description of the policy";
    }
    leaf admin-state {
      type sr-policy-types:policy-admin-state;
      default 'UP';
      description
        "SR policy administrative state, true for
        enabled, false for disabled";
    }
    leaf priority {
      type uint8;
      default 128;
      description
        "Priority considered when policy is recomputed due to
        topology changes";
    }
  }

  grouping policy-properties_state {
    description
      "SR policy property grouping";
    leaf oper-state {
      type sr-policy-types:policy-oper-state;
      config false;
      description
        "SR policy operational state";
    }
    leaf transition-count {
      type uint32;
      config false;
      description "Indicates number of up/down transitions";
    }
    leaf up-time {
      type yang:date-and-time;
      config false;
      description "Policy up time in seconds";
    }
    leaf down-time {
      type yang:date-and-time;
      config false;
      description "Policy down time in seconds";
    }
  }

  grouping policy-properties {
    description
      "SR policy properties";
    uses policy-properties_config;
    uses policy-properties_state;
    uses binding-sid-properties;
    uses forwarding-counters;
  }

  grouping candidate-path-type {
    description "Candidate path type grouping";
    choice type {
      description
        "Type of candidate paths";
      case explicit {
        description
          "Candidate path with explicitly defined set/s of
          segment-lists";
        uses explicit-path-properties;
      }
      case dynamic {
        description
          "Candidate path with dynamic computed segment-lists";
        uses dynamic-path-properties;
      }
      case composite {
        description
          "Candidate path that groups SR policies each with explicit
          and/or dynamic candidate path with potentially different
          optimization objectives and constraints";
        uses composite-path-properties;
      }

    }
  }

  grouping candidate-paths {
    description "SR policy candidate path grouping";
    container candidate-paths {
      description "SR policy candidate path(s) ";

      list candidate-path {
        key "protocol-origin originator-asn originator-node-address
          discriminator";
        unique "preference";

        description "SR policy Candidate path(s) list entry";

        leaf protocol-origin {
          type identityref {
            base sr-policy-types:protocol-origin-type;
          }
          description
            "Instantiation mechanism used to create the candidate
            path";
        }
        leaf originator-asn {
          type uint32;
          description
            "The autonomous system number (ASN) of the provisioning
            node. If 2-byte ASNs are in use, the low-order 16 bits
            MUST be used, and the high-order bits MUST be set to 0";
        }
        leaf originator-node-address {
          type sr-policy-types:node-address-type;
          description
            "represented as a 128-bit value. IPv4 addresses MUST be
            encoded in the lowest 32 bits, and the high-order bits
            MUST be set to 0";
        }
        leaf discriminator {
          type uint32;
          description "Candidate path distinguisher";
        }
        leaf preference {
          type uint32 {
            range "1..65535";
          }
          mandatory true;
          description "Candidate path preference";
        }
        leaf name {
          type string;
          description "Candidate path name";
        }
        leaf description {
          type string;
          description "Candidate path description";
        }
        leaf drop-upon-invalid {
          type boolean;
          description "Enable traffic dropping when LSP is invalid";
        }
        leaf admin-state {
          type boolean;
          description "Shutdown the candidate-path";
        }
        container binding-sid {
          if-feature capability-candidate-path-binding-sid;
          description
            "Binding segment ID";
          uses binding-sid_config;
        }

        uses candidate-path-type;
        uses candidate-path_state;
        uses cpath-cmn-properties;
      }
    }
  }

  grouping policies {
    description "SR policy grouping";
    container policies {
      description "SR Policy container";

      list policy {
        key "color endpoint";
        unique "name";

        description "SR Policy properties";

        uses policy-properties;
        uses candidate-paths;
      }
    }
  }

  grouping explicit-binding-sid-rules {
    description
      "Grouping for explicit binding sid rules";

    list explicit-binding-sid-rules {
      key "index";
      description
        "Explicit binding sid rules applicable for all policies";
      leaf index {
        type uint32;
        description "Explicit binding SID rules list index";
      }
      leaf rule {
        type sr-policy-types:explicit-binding-sid-rule-type;
        mandatory true;
        description "Explicit binding sid rule";
      }
    }
  }

  augment "/rt:routing" {
    description
      "This augments routing-instance configuration with
      segment-routing sr-policy.";
    container segment-routing {
      description "Main segment routing container";
      container traffic-engineering {
        description "Traffic-engineering container";

        uses attributes;

        uses policies;
      }
    }
  }

  /* Notifications */

  notification sr-policy-oper-state-change-event {
    description
      "Notification event when the operational state of the SR policy
      changes";

    leaf policy-name-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:name";
      }
      description "Reference to sr-policy name";
    }

    leaf policy-color-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:color";
      }
      description "Reference to sr-policy color";
    }

    leaf policy-endpoint-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:endpoint";
      }
      description "Reference to sr-policy endpoint";
    }

    leaf policy-new-oper-state  {
      type sr-policy-types:policy-oper-state;
      description "New operational state of the SR policy";
    }

    leaf policy-down-reason {
      type identityref {
        base sr-policy-types:policy-down-reason;
      }
      description
        "Down reason if the SR policy's new operational state is
        down";
    }
  }

  notification sr-policy-candidate-path-change-event {
    description
      "Notification event when candidate path changes for SR policy";

    leaf policy-name-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:name";
      }
      description "Reference to sr-policy name";
    }

    leaf policy-color-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:color";
      }
      description "Reference to sr-policy color";
    }

    leaf policy-endpoint-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:endpoint";
      }
      description "Reference to sr-policy endpoint";
    }

    leaf existing-preference {
      type uint32;
      description "Existing candidate path preference";
    }

    leaf new-preference {
      type uint32;
      description "New candidate path preference";
    }
  }

  notification sr-policy-binding-sid-unavailable-event {
    description
      "Notification event when the binding sid of sr-policy is
      unavailable";

    leaf policy-name-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:name";
      }
      description "Reference to sr-policy name";
    }

    leaf policy-color-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:color";
      }
      description "Reference to sr-policy color";
    }

    leaf policy-endpoint-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:endpoint";
      }
      description "Reference to sr-policy endpoint";
    }

    leaf policy-binding-sid-value-ref {
      if-feature capability-candidate-path-binding-sid;
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:binding-sid/"
          + "sr-policy:value";
      }
      description "Reference to sr-policy binding-sid value";
    }

    leaf reason {
      type identityref {
        base sr-policy-types:binding-sid-unavailable-reason;
      }
      description
        "Reason why the binding sid is unavailable";
    }
  }

  notification sr-policy-candidate-path-binding-sid-mismatch-event {
    description
      "Notification event when binding sid of requested candidate
      path is different from the binding sid of the existing
      candidate path";

    leaf policy-color-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:color";
      }
      description "Reference to sr-policy color";
    }

    leaf policy-endpoint-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:endpoint";
      }
      description "Reference to sr-policy endpoint";
    }

    leaf existing-candidate-path-protocol-origin-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:candidate-paths/"
          + "sr-policy:candidate-path/"
          + "sr-policy:protocol-origin";
      }
      description
        "Reference to existing candidate path protocol origin";
    }

    leaf existing-candidate-path-preference-ref {
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:candidate-paths/"
          + "sr-policy:candidate-path/"
          + "sr-policy:preference";
      }
      description "Reference to existing candidate path preference";
    }

    leaf existing-candidate-path-binding-sid-dataplane-ref {
      if-feature capability-candidate-path-binding-sid;
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:candidate-paths/"
          + "sr-policy:candidate-path/"
          + "sr-policy:binding-sid/"
          + "sr-policy:dataplane";
      }
      description
        "Reference to existing candidate path binding sid dataplane
        type";
    }

    leaf existing-candidate-path-binding-sid-value-ref {
      if-feature capability-candidate-path-binding-sid;
      type leafref {
        path "/rt:routing/"
          + "sr-policy:segment-routing/"
          + "sr-policy:traffic-engineering/"
          + "sr-policy:policies/"
          + "sr-policy:policy/"
          + "sr-policy:candidate-paths/"
          + "sr-policy:candidate-path/"
          + "sr-policy:binding-sid/"
          + "sr-policy:value";
      }
      description
        "Reference to existing candidate path binding sid value";
    }

    leaf conflicting-candidate-path-protocol-origin {
      type uint8;
      description "Conflicting candidate path protocol origin";
    }

    leaf conflicting-candidate-path-preference {
      type uint32;
      description "Conflicting candidate path preference";
    }

    leaf conflicting-candidate-path-binding-sid-dataplane {
      type sr-policy-types:dataplane-type;
      description
        "Conflicting candidate path binding sid dataplane type";
    }

    leaf conflicting-candidate-path-binding-sid-value {
      type sr-policy-types:sid-value-type;
      description "Conflicting candidate path binding sid value";
    }
  }

  /* Features */

  feature capability-candidate-path-binding-sid {
    description
      "This feature enables the capability of specifying binding-sid
      for a candidate path.";
  }
}

<CODE ENDS>
Figure 5: ietf-sr-policy.yang

8. Security Considerations

The configuration, state, and notification data defined using YANG data models in this document are likely to be accessed via the protocols such as NETCONF [RFC6241] etc.

Hence, YANG implementations MUST comply with the security requirements specified in section 15 of [RFC6020]. Additionally, NETCONF implementations MUST comply with the security requirements specified in sections 2.2, 2.3 and 9 of [RFC6241] as well as section 3.7 of [RFC8341].

9. IANA Considerations

This document requests the registration of the following URIs in the IETF "XML registry" [RFC3688]:

Table 2
URI Registrant XML
urn:ietf:params:xml:ns:yang:ietf-sr-policy-types The IESG N/A
urn:ietf:params:xml:ns:yang:ietf-sr-policy The IESG N/A

This document requests the registration of the following YANG modules in the "YANG Module Names" registry [RFC6020]:

Table 3
Name Namespace Prefix Reference
ietf-sr-policy-types urn:ietf:params:xml:ns:yang:ietf-sr-policy-types sr-policy-types This document
ietf-sr-policy urn:ietf:params:xml:ns:yang:ietf-sr-policy sr-policy This document

10. Acknowledgments

The authors of this document/YANG model would like to acknowledge the contributions/reviews by Johnson Thomas, Clarence Filsfils, Siva Sivabalan, Tarek Saad, Kris Michielsen, Dhanendra Jain, Ketan Talaulikar, Bhupendra Yadav, and Bruno Decraene.

11. References

11.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[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>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[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>.
[RFC8342]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/info/rfc8342>.
[RFC8402]
Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, , <https://www.rfc-editor.org/info/rfc8402>.
[RFC8407]
Bierman, A., "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", BCP 216, RFC 8407, DOI 10.17487/RFC8407, , <https://www.rfc-editor.org/info/rfc8407>.
[RFC9256]
Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov, A., and P. Mattes, "Segment Routing Policy Architecture", RFC 9256, DOI 10.17487/RFC9256, , <https://www.rfc-editor.org/info/rfc9256>.

11.2. Informative References

[I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., and D. Jain, "Advertising Segment Routing Policies in BGP", Work in Progress, Internet-Draft, draft-ietf-idr-segment-routing-te-policy-26, , <https://datatracker.ietf.org/doc/html/draft-ietf-idr-segment-routing-te-policy-26>.

Appendix A. Contributors

Robert Sawaya Cisco Systems Email: rsawaya@cisco.com

Authors' Addresses

Kamran Raza (editor)
Cisco Systems
Tarik Saleh
Cisco Systems
Zhuang Shunwan
Huawei Technologies
Daniel Voyer
Bell Canada
Muhammad Durrani
Equinix
Satoru Matsushima
SoftBank
Vishnu Pavan Beeram
Juniper Networks