Network Working Group Enke Chen
Internet Draft Cisco Systems
Expiration Date: July 2006 Vincent Gillet
France Telecom
Subcodes for BGP Cease Notification Message
draft-ietf-idr-cease-subcode-07.txt
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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.
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1. 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].
2. 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.
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, sect. 7].
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+-------------------------------+
| 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".
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 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] was true for this peer when
re-trying a BGP connection after the speaker receives a Cease
NOTIFICATION message with subcode of "Administrative Shutdown", or
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"Peer De-configured", or "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.
7. Acknowledgments
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] Y. Rekhter, T. Li and S. Hares, Eds., "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[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.
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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.
9. Author Information
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
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11. Full Copyright Notice
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