Segment Routing Prefix Segment Identifier Extensions for BGP
RFC 8669
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Type |
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RFC - Proposed Standard
(December 2019; No errata)
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Last updated |
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2019-12-06
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Replaces |
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draft-keyupate-idr-bgp-prefix-sid
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IETF
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plain text
html
xml
pdf
htmlized
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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John Scudder
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Shepherd write-up |
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Show
(last changed 2018-05-18)
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| IESG |
IESG state |
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RFC 8669 (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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Susan Hares <shares@ndzh.com>, aretana.ietf@gmail.com, John Scudder <jgs@juniper.net>
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IANA review state |
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Version Changed - Review Needed
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IANA action state |
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RFC-Ed-Ack
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Internet Engineering Task Force (IETF) S. Previdi
Request for Comments: 8669 Huawei Technologies
Category: Standards Track C. Filsfils
ISSN: 2070-1721 A. Lindem, Ed.
Cisco Systems
A. Sreekantiah
H. Gredler
RtBrick Inc.
December 2019
Segment Routing Prefix Segment Identifier Extensions for BGP
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. The ingress node prepends an SR header to a packet
containing a set of segment identifiers (SIDs). Each SID represents
a topological or service-based instruction. Per-flow state is
maintained only on the ingress node of the SR domain. An "SR domain"
is defined as a single administrative domain for global SID
assignment.
This document defines an optional, transitive BGP attribute for
announcing information about BGP Prefix Segment Identifiers (BGP
Prefix-SIDs) and the specification for SR-MPLS SIDs.
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/rfc8669.
Copyright Notice
Copyright (c) 2019 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.
Table of Contents
1. Introduction
2. MPLS BGP Prefix-SID
3. BGP Prefix-SID Attribute
3.1. Label-Index TLV
3.2. Originator SRGB TLV
4. Receiving BGP Prefix-SID Attribute
4.1. MPLS Data Plane: Labeled Unicast
5. Advertising BGP Prefix-SID Attribute
5.1. MPLS Data Plane: Labeled Unicast
6. Error Handling of BGP Prefix-SID Attribute
7. IANA Considerations
8. Manageability Considerations
9. Security Considerations
10. References
10.1. Normative References
10.2. Informative References
Acknowledgements
Contributors
Authors' Addresses
1. Introduction
The Segment Routing (SR) architecture leverages the source-routing
paradigm. A segment represents either a topological instruction,
such as "go to prefix P following shortest path", or a service
instruction. Other types of segments may be defined in the future.
A segment is identified through a Segment Identifier (SID). An "SR
domain" is defined as a single administrative domain for global SID
assignment. It may be comprised of a single Autonomous System (AS)
or multiple ASes under consolidated global SID administration.
Typically, the ingress node of the SR domain prepends an SR header
containing SIDs to an incoming packet.
As described in [RFC8402], when SR is applied to the MPLS data plane
([RFC8660]), the SID consists of a label.
[RFC8402] also describes how Segment Routing can be applied to an
IPv6 data plane (SRv6) using an IPv6 routing header containing a
stack of SR SIDs encoded as IPv6 addresses [IPv6-SRH]. The
applicability and support for Segment Routing over IPv6 is beyond the
scope of this document.
A BGP Prefix Segment is a BGP prefix with a Prefix-SID attached. A
BGP Prefix-SID is always a global SID ([RFC8402]) within the SR
domain and identifies an instruction to forward the packet over the
Equal-Cost Multipath (ECMP) best path computed by BGP to the related
prefix. The BGP Prefix-SID is the identifier of the BGP Prefix
Segment. In this document, we always refer to the BGP Prefix Segment
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