Distribution of Diverse BGP Paths
RFC 6774
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RFC - Informational
(November 2012; No errata)
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2018-12-20
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IETF
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RFC 6774 (Informational)
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Ron Bonica
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Internet Engineering Task Force (IETF) R. Raszuk, Ed.
Request for Comments: 6774 NTT MCL
Category: Informational R. Fernando
ISSN: 2070-1721 K. Patel
Cisco Systems
D. McPherson
Verisign
K. Kumaki
KDDI Corporation
November 2012
Distribution of Diverse BGP Paths
Abstract
The BGP4 protocol specifies the selection and propagation of a single
best path for each prefix. As defined and widely deployed today, BGP
has no mechanisms to distribute alternate paths that are not
considered best path between its speakers. This behavior results in
a number of disadvantages for new applications and services.
The main objective of this document is to observe that by simply
adding a new session between a route reflector and its client, the
Nth best path can be distributed. This document also compares
existing solutions and proposed ideas that enable distribution of
more paths than just the best path.
This proposal does not specify any changes to the BGP protocol
definition. It does not require a software upgrade of provider edge
(PE) routers acting as route reflector clients.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
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). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
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/rfc6774.
Raszuk, et al. Informational [Page 1]
RFC 6774 Diverse-BGP-Path Distribution November 2012
Copyright Notice
Copyright (c) 2012 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.
Table of Contents
1. Introduction ....................................................2
2. History .........................................................3
2.1. BGP Add-Paths Proposal .....................................3
3. Goals ...........................................................5
4. Multi-Plane Route Reflection ....................................6
4.1. Co-located Best- and Backup-Path RRs .......................8
4.2. Randomly Located Best- and Backup-Path RRs ................10
4.3. Multi-Plane Route Servers for Internet Exchanges ..........12
5. Discussion on Current Models of IBGP Route Distribution ........13
5.1. Full Mesh .................................................13
5.2. Confederations ............................................14
5.3. Route Reflectors ..........................................15
6. Deployment Considerations ......................................15
7. Summary of Benefits ............................................17
8. Applications ...................................................18
9. Security Considerations ........................................19
10. Contributors ..................................................19
11. Acknowledgments ...............................................20
12. References ....................................................20
12.1. Normative References ....................................20
12.2. Informative References ..................................20
1. Introduction
The current BGP4 protocol specification [RFC4271] allows for the
selection and propagation of only one best path for each prefix. As
defined today, the BGP protocol has no mechanism to distribute paths
other than best path between its speakers. This behavior results in
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