OSPFv3 Extensions for Segment Routing
RFC 8666
Internet Engineering Task Force (IETF) P. Psenak, Ed.
Request for Comments: 8666 S. Previdi, Ed.
Category: Standards Track Cisco Systems, Inc.
ISSN: 2070-1721 December 2019
OSPFv3 Extensions for Segment Routing
Abstract
Segment Routing (SR) allows a flexible definition of end-to-end paths
within IGP topologies by encoding paths as sequences of topological
subpaths called "segments". These segments are advertised by the
link-state routing protocols (IS-IS and OSPF).
This document describes the OSPFv3 extensions required for Segment
Routing with the 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/rfc8666.
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Table of Contents
1. Introduction
2. Terminology
3. Segment Routing Identifiers
3.1. SID/Label Sub-TLV
4. Segment Routing Capabilities
5. OSPFv3 Extended Prefix Range TLV
6. Prefix-SID Sub-TLV
7. Adjacency Segment Identifier (Adj-SID)
7.1. Adj-SID Sub-TLV
7.2. LAN Adj-SID Sub-TLV
8. Elements of Procedure
8.1. Intra-area Segment Routing in OSPFv3
8.2. Inter-area Segment Routing in OSPFv3
8.3. Segment Routing for External Prefixes
8.4. Advertisement of Adj-SID
8.4.1. Advertisement of Adj-SID on Point-to-Point Links
8.4.2. Adjacency SID on Broadcast or NBMA Interfaces
9. IANA Considerations
9.1. "OSPFv3 Extended-LSA TLVs" Registry
9.2. "OSPFv3 Extended-LSA Sub-TLVs" Registry
10. TLV/Sub-TLV Error Handling
11. Security Considerations
12. References
12.1. Normative References
12.2. Informative References
Contributors
Authors' Addresses
1. Introduction
Segment Routing (SR) allows a flexible definition of end-to-end paths
within IGP topologies by encoding paths as sequences of topological
subpaths called "segments". These segments are advertised by the
link-state routing protocols (IS-IS and OSPF). Prefix segments
represent an ECMP-aware shortest path to a prefix (or a node) as per
the state of the IGP topology. Adjacency segments represent a hop
over a specific adjacency between two nodes in the IGP. A prefix
segment is typically a multi-hop path while an adjacency segment, in
most cases, is a one-hop path. SR's control plane can be applied to
both IPv6 and MPLS data planes, and it does not require any
additional signaling (other than IGP extensions). The IPv6 data
plane is out of the scope of this specification; the OSPFv3 extension
for SR with the IPv6 data plane will be specified in a separate
document. When used in MPLS networks, SR paths do not require any
LDP or RSVP-TE signaling. However, SR can interoperate in the
presence of Label Switched Paths (LSPs) established with RSVP or LDP.
This document describes the OSPFv3 extensions required for Segment
Routing with the MPLS data plane.
Segment Routing architecture is described in [RFC8402].
Segment Routing use cases are described in [RFC7855].
2. Terminology
This section lists some of the terminology used in this document:
ABR: Area Border Router
Adj-SID: Adjacency Segment Identifier
AS: Autonomous System
ASBR: Autonomous System Boundary Router
DR: Designated Router
IS-IS: Intermediate System to Intermediate System
LDP: Label Distribution Protocol
LSP: Label Switched Path
MPLS: Multiprotocol Label Switching
OSPF: Open Shortest Path First
SPF: Shortest Path First
RSVP: Resource Reservation Protocol
SID: Segment Identifier
SR: Segment Routing
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