draft-ietf-idr-bgp-gr-notification-05.txt   draft-ietf-idr-bgp-gr-notification-06.txt 
Network Working Group K. Patel Network Working Group K. Patel
Internet-Draft R. Fernando Internet-Draft R. Fernando
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: October 29, 2015 J. Scudder Expires: May 7, 2016 J. Scudder
J. Haas J. Haas
Juniper Networks Juniper Networks
April 27, 2015 November 4, 2015
Notification Message support for BGP Graceful Restart Notification Message support for BGP Graceful Restart
draft-ietf-idr-bgp-gr-notification-05.txt draft-ietf-idr-bgp-gr-notification-06.txt
Abstract Abstract
The current BGP Graceful Restart mechanism limits the usage of BGP The current BGP Graceful Restart mechanism limits the usage of BGP
Graceful Restart to BGP protocol messages other than a BGP Graceful Restart to BGP protocol messages other than a BGP
NOTIFICATION message. This document defines an extension to the BGP NOTIFICATION message. This document defines an extension to the BGP
Graceful Restart that permits the Graceful Restart procedures to be Graceful Restart that permits the Graceful Restart procedures to be
performed when the BGP speaker receives a BGP NOTIFICATION Message. performed when the BGP speaker receives a BGP NOTIFICATION Message or
This document also defines a new BGP NOTIFICATION Cease Error subcode the Hold Time expires. This document also defines a new BGP
to prevent BGP speakers supporting the extension defined in this NOTIFICATION Cease Error subcode to prevent BGP speakers supporting
document from performing a Graceful Restart. the extension defined in this document from performing a Graceful
Restart.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 29, 2015. This Internet-Draft will expire on May 7, 2016.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Modifications to BGP Graceful Restart Capability . . . . . . 3 2. Modifications to BGP Graceful Restart Capability . . . . . . 3
3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 4 3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 4
3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4 3.1. Sending a Hard Reset . . . . . . . . . . . . . . . . . . 4
3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 5 3.2. Receiving a Hard Reset . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 5 4.1. Rules for the Receiving Speaker . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . 6 8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
For many classes of errors, the BGP protocol must send a NOTIFICATION For many classes of errors, the BGP protocol must send a NOTIFICATION
message and reset the peering session to handle the error condition. message and reset the peering session to handle the error condition.
The BGP Graceful Restart extension defined in [RFC4724] requires that The BGP Graceful Restart extension defined in [RFC4724] requires that
normal BGP procedures defined in [RFC4271] be followed when a normal BGP procedures defined in [RFC4271] be followed when a
NOTIFICATION message is sent or received. This document defines an NOTIFICATION message is sent or received. This document defines an
extension to BGP Graceful Restart that permits the Graceful Restart extension to BGP Graceful Restart that permits the Graceful Restart
procedures to be performed when the BGP speaker receives a procedures to be performed when the BGP speaker receives a
NOTIFICATION message. This permits the BGP speaker to avoid flapping NOTIFICATION message or the Hold Time expires. This permits the BGP
reachability and continue forwarding while the BGP speaker restarts speaker to avoid flapping reachability and continue forwarding while
the session to handle errors detected in the BGP protocol. the BGP speaker restarts the session to handle errors detected in the
BGP protocol.
At a high level, this document can be summed up as follows. When a At a high level, this document can be summed up as follows. When a
BGP session is reset, both speakers operate as "Receiving Speakers" BGP session is reset, both speakers operate as "Receiving Speakers"
according to [RFC4724], meaning they retain each other's routes. according to [RFC4724], meaning they retain each other's routes.
This is also true for HOLDTIME expiration. The functionality can be This is also true for HOLDTIME expiration. The functionality can be
defeated using a "Hard Reset" subcode for the BGP NOTIFICATION Cease defeated using a "Hard Reset" subcode for the BGP NOTIFICATION Cease
Error code. If a Hard Reset is used, a full session reset is Error code. If a Hard Reset is used, a full session reset is
performed. performed.
1.1. Requirements Language 1.1. Requirements Language
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Flags for Address Family: Flags for Address Family:
This field contains bit flags relating to routes that were This field contains bit flags relating to routes that were
advertised with the given AFI and SAFI. advertised with the given AFI and SAFI.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|F|N| Reserved | |F|N| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
The usage of second most significant bit "N" is deprecated. This bit The usage of second most significant bit "N" (which was defined in a
MUST be advertised as 0 and MUST be ignored upon receipt. previous draft version of this specification) is deprecated. This
bit MUST be advertised as 0 and MUST be ignored upon receipt.
3. BGP Hard Reset Subcode 3. BGP Hard Reset Subcode
A new BGP NOTIFICATION Cease message subcode is defined known as the A new BGP NOTIFICATION Cease message subcode is defined known as the
BGP Hard Reset Subcode. The value of this subcode is discussed in BGP Hard Reset Subcode. The value of this subcode is discussed in
Section 6. We refer to a BGP NOTIFICATION Cease message with the Section 6. We refer to a BGP NOTIFICATION Cease message with the
Hard Reset subcode as a Hard Reset message, or just a Hard Reset. Hard Reset subcode as a Hard Reset message, or just a Hard Reset.
3.1. Sending a Hard Reset 3.1. Sending a Hard Reset
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3.2. Receiving a Hard Reset 3.2. Receiving a Hard Reset
Whenever a BGP speaker receives a Hard Reset, the speaker MUST Whenever a BGP speaker receives a Hard Reset, the speaker MUST
terminate the BGP session following the standard procedures in terminate the BGP session following the standard procedures in
[RFC4271]. [RFC4271].
4. Operation 4. Operation
A BGP speaker that is willing to receive and send BGP NOTIFICATION A BGP speaker that is willing to receive and send BGP NOTIFICATION
messages in Graceful mode MUST advertise the BGP Graceful messages in Graceful mode MUST advertise the BGP Graceful
Notification Flag "N" using the Graceful Restart Capability as Notification "N" bit using the Graceful Restart Capability as defined
defined in [RFC4724]. in [RFC4724].
When such a BGP Speaker receives a BGP NOTIFICATION message other When such a BGP speaker has received the "N" bit from its peer, and
than a Hard Reset, it MUST follow the rules for the Receiving Speaker receives from that peer a BGP NOTIFICATION message other than a Hard
mentioned in Section 4.1. The BGP speaker generating the BGP Reset, it MUST follow the rules for the Receiving Speaker mentioned
NOTIFICATION message MUST also follow the rules for the Receiving in Section 4.1. The BGP speaker generating the BGP NOTIFICATION
Speaker. message MUST also follow the rules for the Receiving Speaker.
When a BGP speaker resets its session due to a HOLDTIME expiry, it When a BGP speaker resets its session due to a HOLDTIME expiry, it
should generate the relevant BGP NOTIFICATION message as mentioned in should generate the relevant BGP NOTIFICATION message as mentioned in
[RFC4271], but subsequently it MUST follow the rules for the [RFC4271], but subsequently it MUST follow the rules for the
Receiving Speaker mentioned in Section 4.1. Receiving Speaker mentioned in Section 4.1.
A BGP speaker SHOULD NOT send a Hard Reset to a peer from which it
has not received the "N" bit. We note, however, that if it did so
the effect would be as desired in any case, since according to
[RFC4271] and [RFC4724] any NOTIFICATION message, whether recognized
or not, results in a session reset. Thus the only negative effect to
be expected from sending the Hard Reset to a peer that hasn't
advertised compliance to this specification would be that the peer
would be unable to properly log the associated information.
Once the session is re-established, both BGP speakers SHOULD set Once the session is re-established, both BGP speakers SHOULD set
their "Forwarding State" bit to 1. If the "Forwarding State" bit is their "Forwarding State" bit to 1. If the "Forwarding State" bit is
not set, then according to the procedures of [RFC4724] S. 4.2, the not set, then according to the procedures of [RFC4724] S. 4.2, the
relevant routes will be flushed, defeating the goals of this relevant routes will be flushed, defeating the goals of this
specification. specification.
4.1. Rules for the Receiving Speaker 4.1. Rules for the Receiving Speaker
[RFC4724] S. 4.2 defines rules for the Receiving Speaker. These are [RFC4724] S. 4.2 defines rules for the Receiving Speaker. These are
modified as follows. modified as follows.
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in the newly received Graceful Restart Capability, no new actions are in the newly received Graceful Restart Capability, no new actions are
triggered on the Receiving Speaker -- in particular, a clear "N" bit triggered on the Receiving Speaker -- in particular, a clear "N" bit
does not trigger deletion of stale routes. does not trigger deletion of stale routes.
Other than these modifications, the rules for the Receiving Speaker Other than these modifications, the rules for the Receiving Speaker
are as specified in [RFC4724] S. 4.2. are as specified in [RFC4724] S. 4.2.
5. Acknowledgements 5. Acknowledgements
The authors would like to thank Jim Uttaro for the suggestion, and The authors would like to thank Jim Uttaro for the suggestion, and
Chris Hall, Paul Mattes and Robert Raszuk for the review and Bruno Decraene, Chris Hall, Paul Mattes and Robert Raszuk for their
comments. review and comments.
6. IANA Considerations 6. IANA Considerations
IANA is requested to assign a new subcode in the "BGP Cease IANA is requested to assign a new subcode in the "BGP Cease
NOTIFICATION message subcodes" registry. The suggested name for the NOTIFICATION message subcodes" registry. The suggested name for the
code point is "Hard Reset". The suggested value is 9. code point is "Hard Reset". The suggested value is 9.
7. Security Considerations 7. Security Considerations
This extension to BGP does not change the underlying security issues This extension to BGP does not change the underlying security issues
inherent in the existing [RFC4724] and [RFC4271]. inherent in the existing [RFC4724] and [RFC4271].
8. Normative References 8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
[RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement <http://www.rfc-editor.org/info/rfc2119>.
with BGP-4", RFC 3392, November 2002.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Protocol 4 (BGP-4)", RFC 4271, January 2006. Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease [RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease
Notification Message", RFC 4486, April 2006. Notification Message", RFC 4486, DOI 10.17487/RFC4486,
April 2006, <http://www.rfc-editor.org/info/rfc4486>.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. [RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
January 2007. DOI 10.17487/RFC4724, January 2007,
<http://www.rfc-editor.org/info/rfc4724>.
Authors' Addresses Authors' Addresses
Keyur Patel Keyur Patel
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: keyupate@cisco.com Email: keyupate@cisco.com
Rex Fernando Rex Fernando
Cisco Systems Cisco Systems
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