RFC 9020: YANG Data Model for Segment Routing

RFC 9020	SR YANG Data Model	May 2021
Litkowski, et al.	Standards Track	[Page]

Abstract

This document defines three YANG data models. The first is for Segment Routing (SR) configuration and operation, which is to be augmented by different Segment Routing data planes. The next is a YANG data model that defines a collection of generic types and groupings for SR. The third module defines the configuration and operational states for the Segment Routing MPLS data plane.¶

Status of This Memo

This is an Internet Standards Track document.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9020.¶

Copyright Notice

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶

1. Introduction

This document defines three YANG data models [RFC7950]. The first one is for Segment Routing (SR) [RFC8402] configuration and operation. This document does not define the IGP extensions to support SR, but the second module defines generic groupings to be reused by IGP extension modules. The reason for this design choice is to not require implementations to support all IGP extensions. For example, an implementation may support the IS-IS extension but not the OSPF extension. The third YANG data model defines a module that is intended to be used on network elements to configure or operate the SR MPLS data plane [RFC8660].¶

The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342].¶

2. Terminology and Notation

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "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.¶

2.1. Tree Diagram

Tree diagrams used in this document follow the notation defined in [RFC8340].¶

2.2. Prefixes in Data Node Names

In this document, names of data nodes, actions, and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in Table 1.¶

Table 1: Prefixes and Corresponding YANG Modules
Prefix	YANG module	Reference
if	ietf-interfaces	[RFC8343]
rt	ietf-routing	[RFC8349]
rt-types	ietf-routing-types	[RFC8294]
yang	ietf-yang-types	[RFC6991]
inet	ietf-inet-types	[RFC6991]

3. Design of the Data Model

The ietf-segment-routing YANG module augments the routing container in the ietf-routing model [RFC8349] and defines generic SR configuration and operational state. This module is augmented by modules supporting different data planes.¶

Module ietf-segment-routing-mpls augments ietf-segment-routing and supports SR-MPLS data plane configuration and operational state.¶

Module ietf-segment-routing-common defines generic types and groupings that SHOULD be reused by IGP extension modules.¶

module: ietf-segment-routing
  augment /rt:routing:
    +--rw segment-routing

module: ietf-segment-routing-mpls
  augment /rt:routing/sr:segment-routing:
    +--rw sr-mpls
       +--rw bindings
       |  +--rw mapping-server {mapping-server}?
       |  |  +--rw policy* [name]
       |  |     +--rw name       string
       |  |     +--rw entries
       |  |        +--rw mapping-entry* [prefix algorithm]
       |  |           +--rw prefix        inet:ip-prefix
       |  |           +--rw value-type?   enumeration
       |  |           +--rw start-sid     uint32
       |  |           +--rw range?        uint32
       |  |           +--rw algorithm     identityref
       |  +--rw connected-prefix-sid-map
       |  |  +--rw connected-prefix-sid* [prefix algorithm]
       |  |     +--rw prefix               inet:ip-prefix
       |  |     +--rw value-type?          enumeration
       |  |     +--rw start-sid            uint32
       |  |     +--rw range?               uint32
       |  |     +--rw algorithm            identityref
       |  |     +--rw last-hop-behavior?   enumeration
       |  +--rw local-prefix-sid
       |     +--rw local-prefix-sid* [prefix algorithm]
       |        +--rw prefix        inet:ip-prefix
       |        +--rw value-type?   enumeration
       |        +--rw start-sid     uint32
       |        +--rw range?        uint32
       |        +--rw algorithm     identityref
       +--rw srgb
       |  +--rw srgb* [lower-bound upper-bound]
       |     +--rw lower-bound    uint32
       |     +--rw upper-bound    uint32
       +--rw srlb
       |  +--rw srlb* [lower-bound upper-bound]
       |     +--rw lower-bound    uint32
       |     +--rw upper-bound    uint32
       +--ro label-blocks* []
       |  +--ro lower-bound?   uint32
       |  +--ro upper-bound?   uint32
       |  +--ro size?          uint32
       |  +--ro free?          uint32
       |  +--ro used?          uint32
       |  +--ro scope?         enumeration
       +--ro sid-db
          +--ro sid* [target sid source source-protocol binding-type]
             +--ro target             string
             +--ro sid                uint32
             +--ro algorithm?         uint8
             +--ro source             inet:ip-address
             +--ro used?              boolean
             +--ro source-protocol    -> /rt:routing
                                         /control-plane-protocols
                                         /control-plane-protocol/name
             +--ro binding-type       enumeration
             +--ro scope?             enumeration

  notifications:
    +---n segment-routing-srgb-collision
    |  +--ro srgb-collisions* []
    |     +--ro lower-bound?          uint32
    |     +--ro upper-bound?          uint32
    |     +--ro routing-protocol?     -> /rt:routing
    |                                    /control-plane-protocols
    |                                    /control-plane-protocol/name
    |     +--ro originating-rtr-id?   router-or-system-id
    +---n segment-routing-global-sid-collision
    |  +--ro received-target?       string
    |  +--ro new-sid-rtr-id?        router-or-system-id
    |  +--ro original-target?       string
    |  +--ro original-sid-rtr-id?   router-or-system-id
    |  +--ro index?                 uint32
    |  +--ro routing-protocol?      -> /rt:routing
    |                                  /control-plane-protocols
    |                                  /control-plane-protocol/name
    +---n segment-routing-index-out-of-range
       +--ro received-target?    string
       +--ro received-index?     uint32
       +--ro routing-protocol?   -> /rt:routing
                                    /control-plane-protocols
                                    /control-plane-protocol/name

RFC 9020

YANG Data Model for Segment Routing