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Network Working Group                                            E. ChenRequest for Comments: 4486                                 Cisco SystemsCategory: Standards Track                                      V. Gillet                                                          France Telecom                                                              April 2006Subcodes for BGP Cease Notification MessageStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   This document defines several subcodes for the BGP Cease NOTIFICATION   message that would provide more information to aid network operators   in correlating network events and diagnosing BGP peering issues.1.  Introduction   This document defines several subcodes for the BGP Cease NOTIFICATION   message that would provide more information to aid network operators   in correlating network events and diagnosing BGP peering issues.  It   also recommends that a BGP speaker implement a backoff mechanism in   re-trying a BGP connection after the speaker receives a NOTIFICATION   message with certain CEASE subcode.2.  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 inRFC 2119 [RFC-2119].Chen & Gillet               Standards Track                     [Page 1]

RFC 4486        BGP Cease Notification Message Subcodes       April 20063.  Subcode Definition   The following subcodes are defined for the Cease NOTIFICATION   message:      Subcode     Symbolic Name         1        Maximum Number of Prefixes Reached         2        Administrative Shutdown         3        Peer De-configured         4        Administrative Reset         5        Connection Rejected         6        Other Configuration Change         7        Connection Collision Resolution         8        Out of Resources4.  Subcode Usage   If a BGP speaker decides to terminate its peering with a neighbor   because the number of address prefixes received from the neighbor   exceeds a locally configured upper bound (as described in [BGP-4]),   then the speaker MUST send to the neighbor a NOTIFICATION message   with the Error Code Cease and the Error Subcode "Maximum Number of   Prefixes Reached".  The message MAY optionally include the Address   Family information [BGP-MP] and the upper bound in the "Data" field,   as shown in Figure 1, where the meaning and use of the <AFI, SAFI>   tuple is the same as defined in [BGP-MP], Section 7.                  +-------------------------------+                  | AFI (2 octets)                |                  +-------------------------------+                  | SAFI (1 octet)                |                  +-------------------------------+                  | Prefix upper bound (4 octets) |                  +-------------------------------+                     Figure 1: Optional Data Field   If a BGP speaker decides to administratively shut down its peering   with a neighbor, then the speaker SHOULD send a NOTIFICATION message   with the Error Code Cease and the Error Subcode "Administrative   Shutdown".   If a BGP speaker decides to de-configure a peer, then the speaker   SHOULD send a NOTIFICATION message with the Error Code Cease and the   Error Subcode "Peer De-configured".Chen & Gillet               Standards Track                     [Page 2]

RFC 4486        BGP Cease Notification Message Subcodes       April 2006   If a BGP speaker decides to administratively reset the peering with a   neighbor, then the speaker SHOULD send a NOTIFICATION message with   the Error Code Cease and the Error Subcode "Administrative Reset".   If a BGP speaker decides to disallow a BGP connection (e.g., the peer   is not configured locally) after the speaker accepts a transport   protocol connection, then the BGP speaker SHOULD send a NOTIFICATION   message with the Error Code Cease and the Error Subcode "Connection   Rejected".   If a BGP speaker decides to administratively reset the peering with a   neighbor due to a configuration change other than the ones described   above, then the speaker SHOULD send a NOTIFICATION message with the   Error Code Cease and the Error Subcode "Other Configuration Change".   If a BGP speaker decides to send a NOTIFICATION message with the   Error Code Cease as a result of the collision resolution procedure   (as described in [BGP-4]), then the subcode SHOULD be set to   "Connection Collision Resolution".   If a BGP speaker runs out of resources (e.g., memory) and decides to   reset a session, then the speaker MAY send a NOTIFICATION message   with the Error Code Cease and the Error Subcode "Out of Resources".   It is RECOMMENDED that a BGP speaker behave as though the   DampPeerOscillations attribute [BGP-4] were true for this peer when   re-trying a BGP connection after the speaker receives a Cease   NOTIFICATION message with a subcode of "Administrative Shutdown",   "Peer De-configured", "Connection Rejected", or "Out of Resources".   An implementation SHOULD impose an upper bound on the number of   consecutive automatic retries.  Once this bound is reached, the   implementation would stop re-trying any BGP connections until some   administrative intervention, i.e., set the AllowAutomaticStart   attribute [BGP-4] to FALSE.5.  IANA Considerations   This document defines the subcodes 1 - 8 for the BGP Cease   NOTIFICATION message.  Future assignments are to be made using either   the Standards Action process defined in [RFC-2434], or the Early IANA   Allocation process defined in [RFC-4020].  Assignments consist of a   name and the value.6.  Security Considerations   This extension to BGP does not change the underlying security issues   inherent in the existing BGP.Chen & Gillet               Standards Track                     [Page 3]

RFC 4486        BGP Cease Notification Message Subcodes       April 20067.  Acknowledgements   The authors would like to thank Yakov Rekhter, Pedro Marques, Andrew   Lange, and Don Goodspeed for their review and suggestions.8.  References8.1.  Normative References   [BGP-4]    Rekhter, Y., Li, T., and S. Hares, "A Border Gateway              Protocol 4 (BGP-4)",RFC 4271, January 2006.   [BGP-MP]   Bates, T., Rekhter, Y., Chandra, R., and D. Katz,              "Multiprotocol Extensions for BGP-4",RFC 2858, June 2000.   [RFC-2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 2434,              October 1998.   [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.8.2.  Informative References   [RFC-4020] Kompella, K. and A. Zinin, "Early IANA Allocation of              Standards Track Code Points",BCP 100,RFC 4020, February              2005.Chen & Gillet               Standards Track                     [Page 4]

RFC 4486        BGP Cease Notification Message Subcodes       April 2006Authors' Addresses   Enke Chen   Cisco Systems, Inc.   170 W. Tasman Dr.   San Jose, CA 95134   USA   EMail: enkechen@cisco.com   Vincent Gillet   France Telecom Longues Distances   61, rue des Archives   75003 Paris FRANCE   EMail: vgi@opentransit.netChen & Gillet               Standards Track                     [Page 5]

RFC 4486        BGP Cease Notification Message Subcodes       April 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Chen & Gillet               Standards Track                     [Page 6]