draft-ietf-idr-dynamic-cap-09.txt   draft-ietf-idr-dynamic-cap-10.txt 
Network Working Group Enke Chen Network Working Group E. Chen
Internet Draft S. Sangli Internet Draft S. Sangli
Expiration Date: May 2007 Cisco Systems Expiration Date: July 16, 2010 Cisco Systems
January 15, 2010
Dynamic Capability for BGP-4 Dynamic Capability for BGP-4
draft-ietf-idr-dynamic-cap-10.txt
draft-ietf-idr-dynamic-cap-09.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any This Internet-Draft is submitted to IETF in full conformance with the
applicable patent or other IPR claims of which he or she is aware provisions of BCP 78 and BCP 79.
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html
This Internet-Draft will expire on July 16, 2010.
Copyright Notice
Copyright (c) 2010 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 in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract Abstract
This document defines a new BGP capability termed "Dynamic This document defines a new BGP capability termed "Dynamic
Capability", which would allow the dynamic update of capabilities Capability", which would allow the dynamic update of capabilities
over an established BGP session. This capability would facilitate over an established BGP session. This capability would facilitate
non-disruptive capability changes by BGP speakers. non-disruptive capability changes by BGP speakers.
1. Introduction 1. Introduction
Currently BGP capabilities [BGP-CAP] are only advertised in the OPEN Currently BGP capabilities [RFC5492] are only advertised in the OPEN
message during the session initialization. In order to enable a new message during the session initialization. In order to enable a new
capability or remove an existing capability (such as an Address capability or remove an existing capability (such as an Address
Family support [BGP-MP]), an established session needs to be reset, Family support [RFC4760]), an established session needs to be reset,
which may disrupt other services running over the session. which may disrupt other services running over the session.
This document defines a new BGP capability termed "Dynamic This document defines a new BGP capability termed "Dynamic
Capability", which would allow the dynamic update of capabilities Capability", which would allow the dynamic update of capabilities
over an established BGP session. This capability would facilitate over an established BGP session. This capability would facilitate
non-disruptive capability changes by BGP speakers. non-disruptive capability changes by BGP speakers.
2. Specification of Requirements 1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC-2119]. document are to be interpreted as described in [RFC2119].
3. Dynamic Capability 2. Dynamic Capability
The Dynamic Capability is a new BGP capability [BGP-CAP]. The The Dynamic Capability is a new BGP capability [RFC5492]. The
Capability Code for this capability is specified in the "IANA Capability Code for this capability is specified in the "IANA
Considerations" section of this document. The Capability Value field Considerations" section of this document. The Capability Value field
consists of a list of capability codes (one-octet for each) that consists of a list of capability codes (one-octet for each) that
specify the capabilities that MAY be revised dynamically by the specify the capabilities that MAY be revised dynamically by the
remote speaker. remote speaker.
By advertising the Dynamic Capability to a peer in the OPEN, a BGP By advertising the Dynamic Capability to a peer in the OPEN, a BGP
speaker conveys to the peer that the speaker is capable of receiving speaker conveys to the peer that the speaker is capable of receiving
and properly handling the CAPABILITY message (as defined in the next and properly handling the CAPABILITY message (as defined in the next
Section) from the peer after the BGP session has been established. Section) from the peer after the BGP session has been established.
4. Capability Message 3. Capability Message
The CAPABILITY Message is a new BGP message type with type code 6. The CAPABILITY Message is a new BGP message type with type code 6.
In addition to the fixed-size BGP header [BGP-4], the CAPABILITY In addition to the fixed-size BGP header [RFC4271], the CAPABILITY
message contains one or more of the following tuples of capability message contains one or more of the following tuples of capability
revisions: revisions:
+------------------------------+ +------------------------------+
| Init/Ack (1 bit) | | Init/Ack (1 bit) |
+------------------------------+ +------------------------------+
| Ack Request (1 bit) | | Ack Request (1 bit) |
+------------------------------+ +------------------------------+
| Reserved (5 bits) | | Reserved (5 bits) |
+------------------------------+ +------------------------------+
skipping to change at page 3, line 26 skipping to change at page 4, line 26
| Capability Code (1 octet) | | Capability Code (1 octet) |
+------------------------------+ +------------------------------+
| Capability Length (2 octets) | | Capability Length (2 octets) |
+------------------------------+ +------------------------------+
| Capability Value (variable) | | Capability Value (variable) |
+------------------------------+ +------------------------------+
The Init/Ack bit indicates whether a capability revision is being The Init/Ack bit indicates whether a capability revision is being
initiated (when set to 0), or being acknowledged (when set to 1). initiated (when set to 0), or being acknowledged (when set to 1).
The Ack Request bit indicates whether an acknowledgement is requested The Ack Request bit indicates whether an acknowledgment is requested
(when set to 1), or not (when set to 0) for a capability revision (when set to 1), or not (when set to 0) for a capability revision
being initiated. being initiated.
The Reserved bits should be set to zero by the sender and ignored by The Reserved bits should be set to zero by the sender and ignored by
the receiver. the receiver.
The Action bit is 0 for advertising a capability, and 1 for removing The Action bit is 0 for advertising a capability, and 1 for removing
a capability. a capability.
The Sequence Number field can be used by a BGP speaker to match an The Sequence Number field can be used by a BGP speaker to match an
acknowledgement with a capability revision that the speaker initiated acknowledgment with a capability revision that the speaker initiated
previously. previously.
Conceptually the triple <Capability Code, Capability Length, Conceptually the triple <Capability Code, Capability Length,
Capability Value> is the same as the one defined in [BGP-CAP], and it Capability Value> is the same as the one defined in [RFC5492], and it
specifies a capability for which the "Action" shall be applied. The specifies a capability for which the "Action" shall be applied. The
triple is optional when the Init/Ack bit is set to 1. triple is optional when the Init/Ack bit is set to 1.
5. Operation 4. Operation
A BGP speaker that is willing to receive the CAPABILITY message (for A BGP speaker that is willing to receive the CAPABILITY message (for
one or more capability codes) from its peer SHOULD use the BGP one or more capability codes) from its peer SHOULD use the BGP
Capabilities Advertisement [BGP-CAP] to advertise the Dynamic Capabilities Advertisement [RFC5492] to advertise the Dynamic
Capability for these capability codes. Capability for these capability codes.
A BGP speaker MAY send to its peer a CAPABILITY message to initiate A BGP speaker MAY send to its peer a CAPABILITY message to initiate
revisions for one or more capability codes only if these capability revisions for one or more capability codes only if these capability
codes are listed in the Dynamic Capability of the OPEN message codes are listed in the Dynamic Capability of the OPEN message
received from its peer. received from its peer.
A CAPABILITY message MAY be received only in the Established state. A CAPABILITY message MAY be received only in the Established state.
Receiving a CAPABILITY message in any other state is a Finite State Receiving a CAPABILITY message in any other state is a Finite State
Machine Error as defined in [BGP-4]. A BGP speaker SHOULD reset the Machine Error as defined in [RFC4271]. A BGP speaker SHOULD reset the
HoldTimer upon receiving a CAPABILITY message from its peer. HoldTimer upon receiving a CAPABILITY message from its peer.
When a BGP speaker sends a CAPABILITY message to its peer to initiate When a BGP speaker sends a CAPABILITY message to its peer to initiate
a capability revision, the Init/Ack bit for the capability revision a capability revision, the Init/Ack bit for the capability revision
in the message MUST be set to 0. The setting of the Ack Request bit in the message MUST be set to 0. The setting of the Ack Request bit
is capability specific. The assignment of the Sequence Number is a is capability specific. The assignment of the Sequence Number is a
local matter, but MUST allow the BGP speaker to unambiguously local matter, but MUST allow the BGP speaker to unambiguously
identify a capability revision it initiated previously based on the identify a capability revision it initiated previously based on the
Sequence Number carried in the acknowledgement from the peer. Sequence Number carried in the acknowledgment from the peer.
If the Init/Ack bit is set to 1 for a capability revision in a If the Init/Ack bit is set to 1 for a capability revision in a
CAPABILITY message received by a BGP speaker, then the BGP speaker CAPABILITY message received by a BGP speaker, then the BGP speaker
SHALL treat the capability revision as an acknowledgement of the SHALL treat the capability revision as an acknowledgment of the
receipt of a capability revision initiated by the BGP speaker. The receipt of a capability revision initiated by the BGP speaker. The
BGP speaker MUST ignore the Ack Request bit, and SHALL use the BGP speaker MUST ignore the Ack Request bit, and SHALL use the
Sequence Number carried in the capability revision to match with the Sequence Number carried in the capability revision to match with the
capability revision previously initiated. The BGP speaker SHALL capability revision previously initiated. The BGP speaker SHALL
ignore an acknowledgement for a capability revision in which an ignore an acknowledgment for a capability revision in which an
acknowledgement was not requested by the BGP speaker. If the acknowledgment was not requested by the BGP speaker. If the Sequence
Sequence Number carried in the capability revision does not match any Number carried in the capability revision does not match any of the
of the the Sequence Numbers used in the capability revisions the Sequence Numbers used in the capability revisions initiated by
initiated by the BGP speaker, then the BGP speaker SHOULD send a the BGP speaker, then the BGP speaker SHOULD send a NOTIFICATION
NOTIFICATION message as specified in the Error Handling section. message as specified in the Error Handling section.
If the Init/Ack bit is set to 0 for a capability revision in a If the Init/Ack bit is set to 0 for a capability revision in a
CAPABILITY message received by a BGP speaker, then the BGP speaker CAPABILITY message received by a BGP speaker, then the BGP speaker
SHOULD first validate the capability code in the message. If the SHOULD first validate the capability code in the message. If the
capability code is not listed in the Dynamic Capability advertised by capability code is not listed in the Dynamic Capability advertised by
the speaker to the peer, the BGP speaker SHOULD send a NOTIFICATION the speaker to the peer, the BGP speaker SHOULD send a NOTIFICATION
message as specified in the Error Handling section. For a valid message as specified in the Error Handling section. For a valid
capability code, if the Ack Request bit is set to 1, the BGP speaker capability code, if the Ack Request bit is set to 1, the BGP speaker
MUST first send a CAPABILITY message to acknowledge the receipt of MUST first send a CAPABILITY message to acknowledge the receipt of
the capability revision. The Init/Ack bit in the acknowledgement the capability revision. The Init/Ack bit in the acknowledgment MUST
MUST be set to 1, and all the other fields in the capability revision be set to 1, and all the other fields in the capability revision MUST
MUST be kept unchanged except that the triple <Capability Code, be kept unchanged except that the triple <Capability Code, Capability
Capability Length, Capability Value> MAY be optionally excluded. Length, Capability Value> MAY be optionally excluded.
After receiving a capability revision initiated by a peer, the BGP After receiving a capability revision initiated by a peer, the BGP
speaker SHALL update the capability previously received from that speaker SHALL update the capability previously received from that
peer based on the Action bit in the message, and then function in peer based on the Action bit in the message, and then function in
accordance with the revised capability for the peer. The procedures accordance with the revised capability for the peer. The procedures
specified in the "Error Handling" section SHOULD be followed when an specified in the "Error Handling" section SHOULD be followed when an
error is detected in processing the CAPABILITY message. error is detected in processing the CAPABILITY message.
In order to avoid ambiguities in sending and processing UPDATE In order to avoid ambiguities in sending and processing UPDATE
messages, certain capability revisions may require close coordination messages, certain capability revisions may require close coordination
between the BGP speaker (the Initiator) that initiates the capability between the BGP speaker (the Initiator) that initiates the capability
revisions and another BGP speaker (the Receiver) that receives the revisions and another BGP speaker (the Receiver) that receives the
capability revisions. The mechanism of acknowledgement defined in capability revisions. The mechanism of acknowledgment defined in
this document SHALL be used for the revision of such a capability. this document SHALL be used for the revision of such a capability.
For the Initiator, the capability revision SHALL take effect (for For the Initiator, the capability revision SHALL take effect (for
sending updates) immediately after the capability revision is sent, sending updates) immediately after the capability revision is sent,
and the capability revision SHALL take effect (for receiving updates) and the capability revision SHALL take effect (for receiving updates)
immediately after an acknowledgement is received from the Receiver. immediately after an acknowledgment is received from the Receiver.
For the Receiver, the capability revision SHALL take effect (for For the Receiver, the capability revision SHALL take effect (for
receiving updates) immediately after the capability revision is receiving updates) immediately after the capability revision is
received from the Initiator, and the capability revision SHALL take received from the Initiator, and the capability revision SHALL take
effect (for sending updates) immediately after an acknowledgement is effect (for sending updates) immediately after an acknowledgment is
sent. sent.
6. Error Handling 5. Error Handling
This document defines a new NOTIFICATION error code: This document defines a new NOTIFICATION error code:
Error Code Symbolic Name Error Code Symbolic Name
7 CAPABILITY Message Error 7 CAPABILITY Message Error
The following error subcodes are defined as well: The following error subcodes are defined as well:
Subcode Symbolic Name Subcode Symbolic Name
skipping to change at page 6, line 11 skipping to change at page 7, line 11
4 Unsupported Capability Code 4 Unsupported Capability Code
If a BGP speaker detects an error while processing a CAPABILITY If a BGP speaker detects an error while processing a CAPABILITY
message, it MUST send a NOTIFICATION message with Error Code message, it MUST send a NOTIFICATION message with Error Code
CAPABILITY Message Error. If any of the defined error subcode is CAPABILITY Message Error. If any of the defined error subcode is
applicable, the Data field of the NOTIFICATION message MUST contain applicable, the Data field of the NOTIFICATION message MUST contain
the tuple for the capability revision that causes the speaker to send the tuple for the capability revision that causes the speaker to send
the message. the message.
If the Sequence Number carried in a capability revision marked as If the Sequence Number carried in a capability revision marked as
acknowledgement does not match any of the the Sequence Numbers used acknowledgment does not match any of the the Sequence Numbers used in
in the capability revisions initiated by the BGP speaker, then the the capability revisions initiated by the BGP speaker, then the error
error subcode is set to Unknown Sequence Number. subcode is set to Unknown Sequence Number.
If the Capability Length field in the CAPABILITY message is incorrect If the Capability Length field in the CAPABILITY message is incorrect
for a Capability Code, then the error subcode is set to Invalid for a Capability Code, then the error subcode is set to Invalid
Capability Length. Capability Length.
If the Capability Value field in the CAPABILITY message is malformed If the Capability Value field in the CAPABILITY message is malformed
(the definition of "malformed" depends on the Capability Code), then (the definition of "malformed" depends on the Capability Code), then
the error subcode is set to Malformed Capability Value. the error subcode is set to Malformed Capability Value.
If the Capability Code in the CAPABILITY message is not any of the If the Capability Code in the CAPABILITY message is not any of the
capability codes advertised in the Dynamic Capability by the speaker, capability codes advertised in the Dynamic Capability by the speaker,
then the error subcode is set to Unsupported Capability Code. then the error subcode is set to Unsupported Capability Code.
7. IANA Considerations 6. IANA Considerations
This document defines the CAPABILITY message type for BGP with type This document defines the CAPABILITY message type for BGP with type
code 6, and a NOTIFICATION error code and subcodes for the errors in code 6, and a NOTIFICATION error code and subcodes for the errors in
a CAPABILITY message. a CAPABILITY message.
This document uses a BGP capability code to indicate that a BGP This document uses a BGP capability code to indicate that a BGP
speaker supports the Dynamic Capability. The capability code needs speaker supports the Dynamic Capability. The capability code needs
to be assigned by IANA per RFC 2842. to be assigned by IANA per RFC 2842.
8. 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.
9. Acknowledgments 8. Acknowledgments
The authors would like to thank Yakov Rekhter, Ravi Chandra, Dino The authors would like to thank Yakov Rekhter, Ravi Chandra, Dino
Farinacci, Pedro Marques, Chandrashekhar Appanna, Derek Yeung, Bruno Farinacci, Pedro Marques, Chandrashekhar Appanna, Derek Yeung, Bruno
Rijsman and John Scudder for their review and comments. Rijsman and John Scudder for their review and comments.
10. Normative References 9. Normative References
[BGP-4] Rekhter, Y., T. Li, and S. Hares, "A Border Gateway Protocol [RFC4271] Rekhter, Y., T. Li, and S. Hares, "A Border Gateway
4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)," RFC 4271, January 2006.
[BGP-MP] T. Bates, R. Chandra, D. Katz, and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Rekhter, Y., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. "Multiprotocol Extensions for BGP-4", RFC 4760, January 2007.
[BGP-CAP] R. Chandra, J. Scudder, "Capabilities Advertisement with [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
BGP-4", RFC 2842, May 2000. with BGP-4", RFC 5492, February 2009.
[RFC-2119] 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, March 1997.
11. Author Information 10. Authors' Addresses
Enke Chen Enke Chen
Cisco Systems, Inc. Cisco Systems, Inc.
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
Email: enkechen@cisco.com Email: enkechen@cisco.com
Srihari R. Sangli Srihari R. Sangli
Cisco Systems, Inc. Cisco Systems, Inc.
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
Email: rsrihari@cisco.com Email: rsrihari@cisco.com
12. Intellectual Property Considerations
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
13. Full Copyright Notice
Copyright (C) The IETF Trust (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, THE IETF TRUST 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.
 End of changes. 41 change blocks. 
57 lines changed or deleted 68 lines changed or added

This html diff was produced by rfcdiff 1.37b. The latest version is available from http://tools.ietf.org/tools/rfcdiff/