Segment Routing Architecture
RFC 8402
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Type |
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RFC - Proposed Standard
(July 2018; No errata)
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Last updated |
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2018-07-24
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Replaces |
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draft-filsfils-spring-segment-routing
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Stream |
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IETF
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plain text
pdf
html
bibtex
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Reviews |
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WG state
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Submitted to IESG for Publication
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Document shepherd |
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Martin Vigoureux
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Shepherd write-up |
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Show
(last changed 2017-02-21)
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| IESG |
IESG state |
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RFC 8402 (Proposed Standard)
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Consensus Boilerplate |
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Yes
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Telechat date |
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Responsible AD |
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Alvaro Retana
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Send notices to |
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aretana.ietf@gmail.com
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| IANA |
IANA review state |
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Version Changed - Review Needed
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IANA action state |
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No IANA Actions
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Internet Engineering Task Force (IETF) C. Filsfils, Ed.
Request for Comments: 8402 S. Previdi, Ed.
Category: Standards Track L. Ginsberg
ISSN: 2070-1721 Cisco Systems, Inc.
B. Decraene
S. Litkowski
Orange
R. Shakir
Google, Inc.
July 2018
Segment Routing Architecture
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.
Filsfils, et al. Standards Track [Page 1]
RFC 8402 Segment Routing July 2018
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
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
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.
Filsfils, et al. Standards Track [Page 2]
RFC 8402 Segment Routing July 2018
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Link-State IGP Segments . . . . . . . . . . . . . . . . . . . 9
3.1. IGP-Prefix Segment (Prefix-SID) . . . . . . . . . . . . . 9
3.1.1. Prefix-SID Algorithm . . . . . . . . . . . . . . . . 9
3.1.2. SR-MPLS . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.3. SRv6 . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2. IGP-Node Segment (Node-SID) . . . . . . . . . . . . . . . 13
3.3. IGP-Anycast Segment (Anycast-SID) . . . . . . . . . . . . 13
3.3.1. Anycast-SID in SR-MPLS . . . . . . . . . . . . . . . 13
3.4. IGP-Adjacency Segment (Adj-SID) . . . . . . . . . . . . . 15
3.4.1. Parallel Adjacencies . . . . . . . . . . . . . . . . 17
3.4.2. LAN Adjacency Segments . . . . . . . . . . . . . . . 18
3.5. Inter-Area Considerations . . . . . . . . . . . . . . . . 18
4. BGP Segments . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1. BGP-Prefix Segment . . . . . . . . . . . . . . . . . . . 19
4.2. BGP Peering Segments . . . . . . . . . . . . . . . . . . 20
5. Binding Segment . . . . . . . . . . . . . . . . . . . . . . . 21
5.1. IGP Mirroring Context Segment . . . . . . . . . . . . . . 21
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