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Internet Engineering Task Force (IETF)                           E. ChenRequest for Comments: 6286                                       J. YuanUpdates:4271                                              Cisco SystemsCategory: Standards Track                                      June 2011ISSN: 2070-1721Autonomous-System-Wide Unique BGP Identifier for BGP-4Abstract   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 updatesRFC 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 inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://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 toBCP 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 20111.  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 20112.3.  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.comChen & Yuan                  Standards Track                    [Page 4]