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1. Overview

This document defines a YANG data model [RFC7950] that can be used to configure and manage OSPFv2 Segment Routing extensions [RFC2328] [RFC8665] and OSPFv3 Segment Routing extensions [RFC5340] [RFC8666] over the MPLS data plane. The defined YANG data model is an augmentation of the OSPF YANG data model [RFC9129].

1.1. Requirements Language​

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.

1.2. Tree Diagrams​

This document uses the graphical representation of data models defined in [RFC8340].

YANG Module Overview​

The ietf-ospf-sr-mpls YANG module contains the MPLS data plane Segment Routing extensions for both OSPFv2 [RFC8665] and OSPFv3 [RFC8666].

Key Features​

This YANG module provides the following key capabilities:

  1. Support for OSPFv2 and OSPFv3 - A unified data model supports Segment Routing extensions for both OSPF versions
  2. Complete Configuration Support - Includes instance-level, area-level, and interface-level Segment Routing configuration
  3. LSA State Information - Provides operational state data for Segment Routing-related information in OSPF Link State Advertisements (LSAs)

Module Dependencies​

The ietf-ospf-sr-mpls YANG module requires the following support:

  • Base Segment Routing Module [RFC9020] - Defines global Segment Routing configuration independent of any specific routing protocol
  • OSPF Base Model [RFC9129] - Defines basic OSPF configuration and state
  • OSPFv3 Extended LSA Module [RFC9587] - Data model for OSPFv3 Extended LSAs

OSPF Configuration Includes​

  1. OSPF Instance-Level Configuration - Imported from the "ietf-segment-routing-mpls" YANG module, including mapping server bindings and per-protocol Segment Routing Global Block (SRGB)
  2. OSPF Area-Level Configuration - Enable SR-MPLS on all interfaces and advertise SR-MPLS information in LSAs
  3. OSPF Interface-Level Configuration - Adjacency Segment Identifier (Adj-SID) configuration for specific neighbors on multi-access interfaces
  4. TI-LFA Configuration - Topology-Independent Loop-Free Alternate interface-level configuration using the MPLS data plane

LSA Operational State​

The module provides operational state (read-only) additions for OSPFv2 and OSPFv3 LSAs:

OSPFv2 Specific:

  • Extended Prefix Range TLV encoding
  • Prefix-SID sub-TLV encoding
  • SR Algorithm, SID/Label Range TLV, etc.

OSPFv3 Specific:

  • Extended Prefix Range TLV encoding
  • Prefix-SID sub-TLV encoding
  • Adj-SID and LAN Adj-SID sub-TLVs
  • SR Algorithm, SID/Label Range TLV, etc.

Through this YANG model, network operators can configure and manage Segment Routing capabilities in OSPF networks using a standardized approach, enabling flexible traffic engineering and fast reroute capabilities.

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