GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc6286

Internet Engineering Task Force (IETF) E. Chen Request for Comments: 6286 J. Yuan Updates: 4271 Cisco Systems Category: Standards Track June 2011 ISSN: 2070-1721

       Autonomous-System-Wide Unique BGP Identifier for BGP-4

Abstract

 To accommodate situations where the current requirements for the BGP
 Identifier are not met, this document relaxes the definition of the
 BGP Identifier to be a 4-octet, unsigned, non-zero integer and
 relaxes the "uniqueness" requirement so that only Autonomous-System-
 wide (AS-wide) uniqueness of the BGP Identifiers is required.  These
 revisions to the base BGP specification do not introduce any backward
 compatibility issues.   This document updates RFC 4271.

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 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/rfc6286.

Copyright Notice

 Copyright (c) 2011 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.

Chen & Yuan Standards Track [Page 1] RFC 6286 AS-Wide Unique BGP ID for BGP-4 June 2011

1. Introduction

 Currently, the BGP Identifier of a BGP speaker is specified as a
 valid IPv4 host address assigned to the BGP speaker [RFC4271].  In
 addition, the deployed BGP code requires that two BGP speakers be of
 distinct BGP Identifiers in order to establish a BGP connection.
 To accommodate situations where the current requirements for the BGP
 Identifier are not met (such as in the case of an IPv6-only network),
 this document relaxes the definition of the BGP Identifier to be a
 4-octet, unsigned, non-zero integer and relaxes the "uniqueness"
 requirement so that only AS-wide uniqueness of the BGP Identifiers is
 required.  These revisions to the base BGP specification do not
 introduce any backward compatibility issues.

2. Protocol Revisions

 The revisions to the base BGP specification [RFC4271] include the
 definition of the BGP Identifier and procedures for a BGP speaker
 that supports the AS-wide Unique BGP Identifier.

2.1. Definition of the BGP Identifier

 For a BGP speaker that supports the AS-wide Unique BGP Identifier,
 the BGP Identifier is specified as the following:
    The BGP Identifier is a 4-octet, unsigned, non-zero integer that
    should be unique within an AS.  The value of the BGP Identifier
    for a BGP speaker is determined on startup and is the same for
    every local interface and every BGP peer.

2.2. Open Message Error Handling

 For a BGP speaker that supports the AS-wide Unique BGP Identifier,
 the OPEN message error handling related to the BGP Identifier is
 modified as follows:
    If the BGP Identifier field of the OPEN message is zero, or if it
    is the same as the BGP Identifier of the local BGP speaker and the
    message is from an internal peer, then the Error Subcode is set to
    "Bad BGP Identifier".

Chen & Yuan Standards Track [Page 2] RFC 6286 AS-Wide Unique BGP ID for BGP-4 June 2011

2.3. Connection Collision Resolution

 For a BGP speaker that supports the AS-wide Unique BGP Identifier,
 the procedures for connection collision resolution are extended as
 follows to deal with the case in which the two BGP speakers share the
 same BGP Identifier (thus, it is only applicable to an external
 peer):
    If the BGP Identifiers of the peers involved in the connection
    collision are identical, then the connection initiated by the BGP
    speaker with the larger AS number is preserved.
 This extension covers cases in which the 4-octet AS numbers are
 involved [RFC4893].

3. Remarks

 It is noted that a BGP Identifier allocated based on [RFC4271] fits
 the revised definition.
 In case of BGP Confederation, the whole confederation is considered
 as one AS for the purpose of supporting the AS-wide Unique BGP
 Identifier.
 A BGP speaker that supports the AS-wide Unique BGP Identifier cannot
 share a BGP Identifier with its external neighbor until the remote
 BGP speaker is upgraded with software that supports the specified
 revisions.
 In addition to the OPEN message, the BGP Identifier is currently also
 used in the following areas:
 o In the AGGREAGTOR attribute of a route where the combination of a
   BGP Identifier and an AS number uniquely identifies the BGP speaker
   that performs the route aggregation.
 o In the Route Reflection within an AS, where only the BGP Identifier
   of an internal neighbor may be propagated in the route reflection
   related attributes.
 o In the route selection, where the BGP Identifier is not used in
   comparing a route from an internal neighbor and a route from an
   external neighbor.  In addition, routes from BGP speakers with
   identical BGP Identifiers have been dealt with (e.g., parallel BGP
   sessions between two BGP speakers).

Chen & Yuan Standards Track [Page 3] RFC 6286 AS-Wide Unique BGP ID for BGP-4 June 2011

 Therefore, it is concluded that the revisions specified in this
 document do not introduce any backward compatibility issues with the
 current usage of the BGP Identifier.

4. Security Considerations

 This extension to BGP does not introduce new security considerations.
 BGP security considerations are discussed in [RFC4271].

5. Acknowledgments

 The authors would like to thank members of the IDR Working Group for
 discussions on the "IPv6-only Network" related issues that inspired
 this document.

6. Normative References

 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
           Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.
 [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
           Number Space", RFC 4893, May 2007.

Authors' Addresses

 Enke Chen
 Cisco Systems, Inc.
 170 W. Tasman Dr.
 San Jose, CA 95134
 EMail: enkechen@cisco.com
 Jenny Yuan
 Cisco Systems, Inc.
 170 W. Tasman Dr.
 San Jose, CA 95134
 EMail: jenny@cisco.com

Chen & Yuan Standards Track [Page 4]

/data/webs/external/dokuwiki/data/pages/rfc/rfc6286.txt · Last modified: 2011/06/17 16:46 (external edit)