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rfc:rfc4486

Network Working Group E. Chen Request for Comments: 4486 Cisco Systems Category: Standards Track V. Gillet

                                                        France Telecom
                                                            April 2006
            Subcodes for BGP Cease Notification Message

Status 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 in RFC 2119 [RFC-2119].

Chen & Gillet Standards Track [Page 1] RFC 4486 BGP Cease Notification Message Subcodes April 2006

3. 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 Resources

4. 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 2006

7. Acknowledgements

 The authors would like to thank Yakov Rekhter, Pedro Marques, Andrew
 Lange, and Don Goodspeed for their review and suggestions.

8. References

8.1. 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 2006

Authors' 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.net

Chen & Gillet Standards Track [Page 5] RFC 4486 BGP Cease Notification Message Subcodes April 2006

Full Copyright Statement

 Copyright (C) The Internet Society (2006).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 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.

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Acknowledgement

 Funding for the RFC Editor function is provided by the IETF
 Administrative Support Activity (IASA).

Chen & Gillet Standards Track [Page 6]

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