Advertisement of Multiple Paths in BGP
RFC 7911
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Type |
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RFC - Proposed Standard
(July 2016; No errata)
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Last updated |
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2016-07-11
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Replaces |
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draft-walton-bgp-add-paths
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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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Russ White
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Shepherd write-up |
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Show
(last changed 2016-03-25)
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IESG state |
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RFC 7911 (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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Alia Atlas
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Send notices to |
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"Russ White" <russ@riw.us>
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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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RFC-Ed-Ack
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Internet Engineering Task Force (IETF) D. Walton
Request for Comments: 7911 Cumulus Networks
Category: Standards Track A. Retana
ISSN: 2070-1721 E. Chen
Cisco Systems, Inc.
J. Scudder
Juniper Networks
July 2016
Advertisement of Multiple Paths in BGP
Abstract
This document defines a BGP extension that allows the advertisement
of multiple paths for the same address prefix without the new paths
implicitly replacing any previous ones. The essence of the extension
is that each path is identified by a Path Identifier in addition to
the address prefix.
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
http://www.rfc-editor.org/info/rfc7911.
Copyright Notice
Copyright (c) 2016 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
(http://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.
Walton, et al. Standards Track [Page 1]
RFC 7911 ADD-PATH July 2016
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Specification of Requirements . . . . . . . . . . . . . . 2
2. How to Identify a Path . . . . . . . . . . . . . . . . . . . 3
3. Extended NLRI Encodings . . . . . . . . . . . . . . . . . . . 3
4. ADD-PATH Capability . . . . . . . . . . . . . . . . . . . . . 4
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Deployment Considerations . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The BGP specification [RFC4271] defines an Update-Send Process to
advertise the routes chosen by the Decision Process to other BGP
speakers. No provisions are made to allow the advertisement of
multiple paths for the same address prefix or Network Layer
Reachability Information (NLRI). In fact, a route with the same NLRI
as a previously advertised route implicitly replaces the previous
advertisement.
This document defines a BGP extension that allows the advertisement
of multiple paths for the same address prefix without the new paths
implicitly replacing any previous ones. The essence of the extension
is that each path is identified by a Path Identifier in addition to
the address prefix.
The availability of the additional paths can help reduce or eliminate
persistent route oscillations [RFC3345]. It can also help with
optimal routing and routing convergence in a network by providing
potential alternate or backup paths, respectively.
1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Walton, et al. Standards Track [Page 2]
RFC 7911 ADD-PATH July 2016
2. How to Identify a Path
As defined in [RFC4271], a path refers to the information reported in
the Path Attribute field of an UPDATE message. As the procedures
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