draft-ietf-idr-add-paths-00.txt   draft-ietf-idr-add-paths-01.txt 
Network Working Group D. Walton Network Working Group D. Walton
Internet Draft A. Retana Internet Draft A. Retana
Expiration Date: June 2009 E. Chen Intended Status: Standards Track E. Chen
Cisco Systems Expiration Date: December 2009 Cisco Systems
J. Scudder J. Scudder
Juniper Networks Juniper Networks
December 19, 2008 July 27, 2009
Advertisement of Multiple Paths in BGP Advertisement of Multiple Paths in BGP
draft-ietf-idr-add-paths-00.txt draft-ietf-idr-add-paths-01.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF 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
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.
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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/1id-abstracts.html 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 June 19, 2009. This Internet-Draft will expire on December 28, 2009.
Abstract Abstract
In this document we propose a BGP extension that allows the In this document we propose a BGP extension that allows the
advertisement of multiple paths for the same address prefix without advertisement of multiple paths for the same address prefix without
the new paths implicitly replacing any previous ones. The essence of the new paths implicitly replacing any previous ones. The essence of
the extension is that each path is identified by a path identifier in the extension is that each path is identified by a path identifier in
addition to the address prefix. addition to the address prefix.
1. Introduction 1. Introduction
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| ... | | ... |
+--------------------------------+ +--------------------------------+
| Prefix (variable) | | Prefix (variable) |
+--------------------------------+ +--------------------------------+
The usage of the extended NLRI encodings is specified in the The usage of the extended NLRI encodings is specified in the
Operation section. Operation section.
5. ADD-PATH Capability 5. ADD-PATH Capability
The ADD-PATH Capability is a new BGP capability [RFC3392]. The The ADD-PATH 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 Length field Considerations section of this document. The Capability Length field
of this capability is variable. The Capability Value field consists of this capability is variable. The Capability Value field consists
of one or more of the following tuples: of one or more of the following tuples:
+------------------------------------------------+ +------------------------------------------------+
| Address Family Identifier (2 octets) | | Address Family Identifier (2 octets) |
+------------------------------------------------+ +------------------------------------------------+
| Subsequent Address Family Identifier (1 octet) | | Subsequent Address Family Identifier (1 octet) |
+------------------------------------------------+ +------------------------------------------------+
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subsequent advertisements replacing the previous ones. Apart from subsequent advertisements replacing the previous ones. Apart from
the fact that this is now possible, the route advertisement rules of the fact that this is now possible, the route advertisement rules of
[RFC4271] are not changed. In particular, a new advertisement for a [RFC4271] are not changed. In particular, a new advertisement for a
given address prefix and a given path identifier replaces a previous given address prefix and a given path identifier replaces a previous
advertisement for the given address prefix and the given path advertisement for the given address prefix and the given path
identifier. identifier.
A BGP speaker that is willing to receive multiple paths from its A BGP speaker that is willing to receive multiple paths from its
peer, or would like to send multiple paths to its peer, SHOULD peer, or would like to send multiple paths to its peer, SHOULD
advertise the ADD-PATH Capability to the peer using BGP Capabilities advertise the ADD-PATH Capability to the peer using BGP Capabilities
advertisement [RFC3392]. advertisement [RFC5492].
A BGP speaker MUST follow the existing procedures in generating an A BGP speaker MUST follow the existing procedures in generating an
UPDATE message for a particular <AFI, SAFI> to a peer unless the BGP UPDATE message for a particular <AFI, SAFI> to a peer unless the BGP
speaker advertises the ADD-PATH Capability to the peer indicating its speaker advertises the ADD-PATH Capability to the peer indicating its
desire to send multiple paths for the <AFI, SAFI>, and also receives desire to send multiple paths for the <AFI, SAFI>, and also receives
the ADD-PATH Capability from the peer indicating its willingness to the ADD-PATH Capability from the peer indicating its willingness to
receive multiple paths for the <AFI, SAFI>, in which case the speaker receive multiple paths for the <AFI, SAFI>, in which case the speaker
MUST generate a route update for the <AFI, SAFI> based on the MUST generate a route update for the <AFI, SAFI> based on the
combination of the address prefix and the Path Identifier, and use combination of the address prefix and the Path Identifier, and use
the extended NLRI encodings specified in this document. The peer the extended NLRI encodings specified in this document. The peer
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Many people have made valuable comments and suggestions, including Many people have made valuable comments and suggestions, including
Dave Meyer, Srihari Sangli, Eric Rosen, Dan Tappan, Robert Raszuk, Dave Meyer, Srihari Sangli, Eric Rosen, Dan Tappan, Robert Raszuk,
Mark Turner, Danny McPherson, Eugene Kim, Pradosh Mohapatra, Rex Mark Turner, Danny McPherson, Eugene Kim, Pradosh Mohapatra, Rex
Fernando, and Keyur Patel. Fernando, and Keyur Patel.
12. Normative References 12. Normative References
[RFC4271] Rekhter, Y., T. Li, and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., T. Li, and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)," RFC 4271, January 2006. Protocol 4 (BGP-4)," RFC 4271, January 2006.
[RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4," RFC 3392, November 2002. with BGP-4", RFC 5492, February 2009.
[RFC4760] Bates, T., Chandra, R., Rekhter, Y., and D. Katz, [RFC4760] Bates, T., Chandra, R., Rekhter, Y., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 4760, January 2007. "Multiprotocol Extensions for BGP-4", RFC 4760, January 2007.
[RFC3107] Rekhter, R. and E. Rosen, "Carrying Label Information in [RFC3107] Rekhter, R. and E. Rosen, "Carrying Label Information in
BGP-4," RFC 3107, May 2001. BGP-4," RFC 3107, May 2001.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," RFC 2119, BCP 14, March 1997. Requirement Levels," RFC 2119, BCP 14, March 1997.
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Email: enkechen@cisco.com Email: enkechen@cisco.com
John Scudder John Scudder
Juniper Networks Juniper Networks
Email: jgs@juniper.net Email: jgs@juniper.net
15. Copyright Notice 15. Copyright Notice
Copyright (c) 2008 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents in effect on the date of
(http://trustee.ietf.org/license-info) in effect on the date of publication of this document (http://trustee.ietf.org/license-info).
publication of this document. Please review these documents Please review these documents carefully, as they describe your rights
carefully, as they describe your rights and restrictions with respect and restrictions with respect to this document.
to this document.
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