Network Working Group K. Patel
Internet-Draft R. Fernando
Intended status: Standards Track Cisco Systems
Expires: June 8, 2012 J. Scudder
J. Haas
Juniper Networks
December 6, 2011
Notification Message support for BGP Graceful Restart
draft-ietf-idr-bgp-gr-notification-00.txt
Abstract
The current BGP Graceful Restart mechanism limits the usage of BGP
Graceful Restart to BGP protocol messages other than a BGP
NOTIFICATION message. This document defines an extension to the BGP
Graceful Restart that permits the Graceful Restart procedures to be
performed when the BGP speaker receives a BGP NOTIFICATION Message.
This document also defines a new BGP NOTIFICATION Cease Error subcode
to prevent BGP speakers supporting the extension defined in this
document from performing a Graceful Restart.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 8, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
Patel, et al. Expires June 8, 2012 [Page 1]
Internet-Draft Notification support for BGP GR December 2011
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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Patel, et al. Expires June 8, 2012 [Page 2]
Internet-Draft Notification support for BGP GR December 2011
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 4
2. Modifications to BGP Graceful Restart Capability . . . . . . . 4
3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . . 5
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Patel, et al. Expires June 8, 2012 [Page 3]
Internet-Draft Notification support for BGP GR December 2011
1. Introduction
For many classes of errors, the BGP protocol must send a NOTIFICATION
message and reset the peering session to handle the error condition.
The BGP Graceful Restart extension defined in [RFC4724] requires that
normal BGP procedures defined in [RFC4271] be followed when a
NOTIFICATION message is sent or received. This document defines an
extension to BGP Graceful Restart that permits the Graceful Restart
procedures to be performed when the BGP speaker receives a
NOTIFICATION message. This permits the BGP speaker to avoid flapping
reachability and continue forwarding while the BGP speaker restarts
the session to handle errors detected in the BGP protocol.
This document defines a BGP NOTIFICATION cease Error subcode for the
Cease Error code to prevent BGP speakers supporting the extension
defined in this document from performing a Graceful Restart.
1.1. Requirements Language
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 [RFC2119].
2. Modifications to BGP Graceful Restart Capability
The BGP Graceful Restart Capability is augmented to signal the
Graceful Restart support for BGP NOTIFICATION messages. In
particular, the flags field for Address Family is augmented as
follows:
Patel, et al. Expires June 8, 2012 [Page 4]
Internet-Draft Notification support for BGP GR December 2011
+--------------------------------------------------+
| Restart Flags (4 bits) |
+--------------------------------------------------+
| Restart Time in seconds (12 bits) |
+--------------------------------------------------+
| Address Family Identifier (16 bits) |
+--------------------------------------------------+
| Subsequent Address Family Identifier (8 bits) |
+--------------------------------------------------+
| Flags for Address Family (8 bits) |
+--------------------------------------------------+
| ... |
+--------------------------------------------------+
| Address Family Identifier (16 bits) |
+--------------------------------------------------+
| Subsequent Address Family Identifier (8 bits) |
+--------------------------------------------------+
| Flags for Address Family (8 bits) |
+--------------------------------------------------+
Flags for Address Family:
This field contains bit flags relating to routes that were
advertised with the given AFI and SAFI.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|N| Reserved |
+-+-+-+-+-+-+-+-+
The second most significant bit "N" is defined as a BGP Graceful
Notification bit, which is used to indicate the Graceful Restart
support for BGP NOTIFICATION messages. BGP speaker indicates the
Graceful Restart support for BGP NOTIFICATION messages and its
ability to handle the new BGP NOTIFICATION Cease message subcode and
the format for a BGP NOTIFICATION Cease message defined in [RFC4486]
when the Graceful NOTIFICATION bit is set (value 1).
3. BGP Hard Reset Subcode
A new BGP Cease message subcode is defined known as BGP Hard Reset
Subcode. The value of this subcode is 9.
Whenever a BGP speaker receives a NOTIFICATION message with the Cease
Patel, et al. Expires June 8, 2012 [Page 5]
Internet-Draft Notification support for BGP GR December 2011
Error code and Hard Reset Error subcode, the speaker MUST terminate
the BGP session following the standard procedures in [RFC4271].
4. Operation
A BGP speaker that is willing to receive and send BGP NOTIFICATION
messages in Graceful mode should advertise the BGP Graceful
Notification Flag "N" using the Graceful Restart Capability as
defined in [RFC4724].
When a BGP Speaker receives a BGP NOTIFICATION message, it SHOULD
follow the standard rules of the receiving speaker mentioned in
[RFC4724] for all AFI/SAFIs for which it has announced the BGP
Graceful Notification flag. The BGP speaker generating a BGP
NOTIFICATION message SHOULD follow the standard rules of the
receiving Speaker in [RFC4724] for all AFI/SAFIs that were announced
with the BGP Graceful Notification flag.
Once the session is re-established, both BGP speakers MUST set their
"Forwarding State" bit to 1 if they want to apply planned graceful
restart. The handling of the "Forwarding State" bit should be done
as specified by the procedures of the Receiving speaker in [RFC4724]
are applied.
As part of this extension, possible consecutive restarts SHOULD NOT
delete a route (from the peer) previously marked as stale, until
required by rules mentioned in [RFC4724].
5. Acknowledgements
The authors would like to thank Robert Raszuk for the review and
comments.
6. IANA Considerations
This document defines a new BGP Cease message subcode known as BGP
Hard Reset Subcode. IANA mantains the list of existing BGP Cease
message subcodes. This document proposes defining a new BGP Cease
message subcode known as BGP Hard Reset Subcode with the value 9.
7. Security Considerations
This extension to BGP does not change the underlying security issues
inherent in the existing [RFC4724] and [RFC4271]
Patel, et al. Expires June 8, 2012 [Page 6]
Internet-Draft Notification support for BGP GR December 2011
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2842] Chandra, R. and J. Scudder, "Capabilities Advertisement
with BGP-4", RFC 2842, May 2000.
[RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement
with BGP-4", RFC 3392, November 2002.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease
Notification Message", RFC 4486, April 2006.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
January 2007.
8.2. Informative References
[RFC2858] Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
Authors' Addresses
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Rex Fernando
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: rex@cisco.com
Patel, et al. Expires June 8, 2012 [Page 7]
Internet-Draft Notification support for BGP GR December 2011
John Scudder
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089
USA
Email: jgs@juniper.net
Jeff Haas
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089
USA
Email: jhaas@juniper.net
Patel, et al. Expires June 8, 2012 [Page 8]