Network Working Group Enke Chen
Internet Draft Redback Networks
Expiration Date: October 2004 Vincent Gillet
France Telecom
Subcodes for BGP Cease Notification Message
draft-ietf-idr-cease-subcode-05.txt
1. Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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The list of current Internet-Drafts can be accessed at
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The list of Internet-Draft Shadow Directories can be accessed at
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2. Abstract
This document defines several subcodes for the BGP Cease NOTIFICATION
message that would provide more information to aid network operators
in co-relating network events and diagnosing BGP peering issues.
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3. 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].
4. Introduction
This document defines several subcodes for the BGP Cease NOTIFICATION
message that would provide more information to aid network operators
in co-relating network events and diagnosing BGP peering issues.
5. 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 Unconfigured
4 Administrative Reset
5 Connection Rejected
6 Other Configuration Change
7 Connection Collision Resolution
8 Out of Resource
6. 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
with the following format:
+-------------------------------+
| AFI (2 octets) |
+-------------------------------+
| SAFI (1 octet) |
+-------------------------------+
| Prefix upper bound (4 octets) |
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+-------------------------------+
where the meaning and use of the <AFI, SAFI> tuple is the same as
defined in [BGP-MP, sect. 7].
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 unconfigure a peer, then the speaker
SHOULD send a NOTIFICATION message with the Error Code Cease, and the
Error Subcode "Peer Unconfigured".
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 dis-allow 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 resource (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 Resource".
It is RECOMMENDED that a BGP speaker implement a backoff mechanism in
re-trying a BGP connection after the speaker receives a Cease
NOTIFICATION message with subcode of "Administrative Shutdown", or
"Peer Unconfigured", or "Connection Rejected", or "Out of Resource".
An implementation MAY 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.
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7. IANA Considerations
This document defines several subcodes for the BGP Cease NOTIFICATION
messsage. New subcodes MUST only be introduced using the Standards
Action process defined in [RFC-2434].
8. Security Considerations
This extension to BGP does not change the underlying security issues
inherent in the existing BGP.
9. Acknowledgments
The authors would like to thank Yakov Rekhter, Pedro Marques, Andrew
Lange and Don Goodspeed for their review and suggestions.
10. References
[BGP-4] Y. Rekhter, T. Li and S. Hares, "A Border Gateway Protocol 4
(BGP-4)", <draft-ietf-idr-bgp4-23.txt>, November 2003.
[BGP-MP] Bates, T., Chandra, R., Katz, D. and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
[RFC-2434] Narten, T., Alvestrand, H., "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434, October 1998.
[RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
11. Author Information
Enke Chen
Redback Networks, Inc.
300 Holger Way
San Jose, CA 95134
Email: enke@redback.com
Vincent Gillet
France Telecom Longues Distances
246 rue de Bercy
75594 Paris Cedex 12 FRANCE
Email: vgi@opentransit.net
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