RFC 8402 - Segment Routing Architecture

Request for Comments: 8402
Category: Standards Track
ISSN: 2070-1721

Editors:

• C. Filsfils, Cisco Systems, Inc.
• S. Previdi, Cisco Systems, Inc.

Authors:

• L. Ginsberg, Cisco Systems, Inc.
• B. Decraene, Orange
• S. Litkowski, Orange
• R. Shakir, Google, Inc.

Date: July 2018

Abstract

Segment Routing (SR) leverages the source routing paradigm. A node steers a packet through an ordered list of instructions, called "segments". A segment can represent any instruction, topological or service based. A segment can have a semantic local to an SR node or global within an SR domain. SR provides a mechanism that allows a flow to be restricted to a specific topological path, while maintaining per-flow state only at the ingress node(s) to the SR domain.

SR can be directly applied to the MPLS architecture with no change to the forwarding plane. A segment is encoded as an MPLS label. An ordered list of segments is encoded as a stack of labels. The segment to process is on the top of the stack. Upon completion of a segment, the related label is popped from the stack.

SR can be applied to the IPv6 architecture, with a new type of routing header. A segment is encoded as an IPv6 address. An ordered list of segments is encoded as an ordered list of IPv6 addresses in the routing header. The active segment is indicated by the Destination Address (DA) of the packet. The next active segment is indicated by a pointer in the new routing header.

Contents

• 1. Introduction
• 2. Terminology
• 3. Link-State IGP Segments
  • 3.1. IGP-Prefix Segment (Prefix-SID)
  • 3.2. IGP-Node Segment (Node-SID)
  • 3.3. IGP-Anycast Segment (Anycast-SID)
  • 3.4. IGP-Adjacency Segment (Adj-SID)
  • 3.5. Inter-Area Considerations
• 4. BGP Segments
  • 4.1. BGP-Prefix Segment
  • 4.2. BGP Peering Segments
• 5. Binding Segment
  • 5.1. IGP Mirroring Context Segment
• 6. Multicast
• 7. IANA Considerations
• 8. Security Considerations
  • 8.1. SR-MPLS
  • 8.2. SRv6
  • 8.3. Congestion Control
• 9. Manageability Considerations
• 10. References
  • 10.1. Normative References
  • 10.2. Informative References
• Acknowledgements
• Contributors
• Authors' Addresses

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/rfc8402.

Copyright Notice

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