draft-ietf-idr-add-paths-14.txt   draft-ietf-idr-add-paths-15.txt 
Network Working Group D. Walton Network Working Group D. Walton
Internet-Draft Cumulus Networks Internet-Draft Cumulus Networks
Intended status: Standards Track A. Retana Intended status: Standards Track A. Retana
Expires: November 1, 2016 E. Chen Expires: November 24, 2016 E. Chen
Cisco Systems, Inc. Cisco Systems, Inc.
J. Scudder J. Scudder
Juniper Networks Juniper Networks
April 30, 2016 May 23, 2016
Advertisement of Multiple Paths in BGP Advertisement of Multiple Paths in BGP
draft-ietf-idr-add-paths-14 draft-ietf-idr-add-paths-15
Abstract Abstract
This document defines a BGP extension that allows the advertisement This document defines a BGP extension that allows the advertisement
of multiple paths for the same address prefix without the new paths of multiple paths for the same address prefix without the new paths
implicitly replacing any previous ones. The essence of the extension implicitly replacing any previous ones. The essence of the extension
is that each path is identified by a path identifier in addition to is that each path is identified by a path identifier in addition to
the address prefix. the address prefix.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on November 1, 2016. This Internet-Draft will expire on November 24, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3. Extended NLRI Encodings . . . . . . . . . . . . . . . . . . . 3 3. Extended NLRI Encodings . . . . . . . . . . . . . . . . . . . 3
4. ADD-PATH Capability . . . . . . . . . . . . . . . . . . . . . 3 4. ADD-PATH Capability . . . . . . . . . . . . . . . . . . . . . 3
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Deployment Considerations . . . . . . . . . . . . . . . . . . 5 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
The BGP specification [RFC4271] defines an Update-Send Process to The BGP specification [RFC4271] defines an Update-Send Process to
advertise the routes chosen by the Decision Process to other BGP advertise the routes chosen by the Decision Process to other BGP
speakers. No provisions are made to allow the advertisement of speakers. No provisions are made to allow the advertisement of
multiple paths for the same address prefix, or Network Layer multiple paths for the same address prefix, or Network Layer
Reachability Information (NLRI). In fact, a route with the same NLRI Reachability Information (NLRI). In fact, a route with the same NLRI
as a previously advertised route implicitly replaces the previous as a previously advertised route implicitly replaces the previous
advertisement. advertisement.
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unless the BGP speaker advertises the ADD-PATH Capability to the peer unless the BGP speaker advertises the ADD-PATH Capability to the peer
indicating its ability to send multiple paths for the <AFI, SAFI>, indicating its ability to send multiple paths for the <AFI, SAFI>,
and also receives the ADD-PATH Capability from the peer indicating and also receives the ADD-PATH Capability from the peer indicating
its ability to receive multiple paths for the <AFI, SAFI>, in which its ability to receive multiple paths for the <AFI, SAFI>, in which
case the speaker MUST generate a route update for the <AFI, SAFI> case the speaker MUST generate a route update for the <AFI, SAFI>
based on the combination of the address prefix and the Path based on the combination of the address prefix and the Path
Identifier, and use the extended NLRI encodings specified in this Identifier, and use the extended NLRI encodings specified in this
document. The peer SHALL act accordingly in processing an UPDATE document. The peer SHALL act accordingly in processing an UPDATE
message related to a particular <AFI, SAFI>. message related to a particular <AFI, SAFI>.
A BGP speaker SHOULD include the bestpath when more than one path are A BGP speaker SHOULD include the best route [RFC4271] when more than
advertised to a neighbor unless the bestpath is a path received from one path is advertised to a neighbor, unless it is a path received
that neighbor. from that neighbor.
As the Path Identifiers are locally assigned, and may or may not be As the Path Identifiers are locally assigned, and may or may not be
persistent across a control plane restart of a BGP speaker, an persistent across a control plane restart of a BGP speaker, an
implementation SHOULD take special care so that the underlying implementation SHOULD take special care so that the underlying
forwarding plane of a "Receiving Speaker" as described in [RFC4724] forwarding plane of a "Receiving Speaker" as described in [RFC4724]
is not affected during the graceful restart of a BGP session. is not affected during the graceful restart of a BGP session.
6. Deployment Considerations 6. Deployment Considerations
The extension proposed in this document provides a mechanism for a The extension proposed in this document provides a mechanism for a
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described in this document. This registration is in the BGP described in this document. This registration is in the BGP
Capability Codes registry. Capability Codes registry.
8. Security Considerations 8. Security Considerations
This document defines a BGP extension that allows the advertisement This document defines a BGP extension that allows the advertisement
of multiple paths for the same address prefix without the new paths of multiple paths for the same address prefix without the new paths
implicitly replacing any previous ones. As a result, multiple paths implicitly replacing any previous ones. As a result, multiple paths
for a large number of prefixes may be received by a BGP speaker for a large number of prefixes may be received by a BGP speaker
potentially depleting memory resources or even causing network-wide potentially depleting memory resources or even causing network-wide
instability. The use of the ADD-PATH Capability is intended to instability, which can be considered a denial of service attack.
address specific needs related to, for example, eliminating the MED- Note that this is not a new vulnerability, but one that is present in
induced route oscillations in a network the base BGP specification [RFC4272].
[I-D.ietf-idr-route-oscillation-stop]. While describing the
applications for the ADD-PATH Capability is outside the scope of this
document, users are encouraged to examine their behavior and
potential impact by studying the best practices described in
[I-D.ietf-idr-add-paths-guidelines].
This document introduces no new security concerns in the base The use of the ADD-PATH Capability is intended to address specific
operation of BGP [RFC4271]. needs related to, for example, eliminating the MED-induced route
oscillations in a network [I-D.ietf-idr-route-oscillation-stop].
While describing the applications for the ADD-PATH Capability is
outside the scope of this document, users are encouraged to examine
their behavior and potential impact by studying the best practices
described in [I-D.ietf-idr-add-paths-guidelines].
Security concerns in the base operation of BGP [RFC4271] also apply.
9. Acknowledgments 9. Acknowledgments
We would like to thank David Cook and Naiming Shen for their We would like to thank David Cook and Naiming Shen for their
contributions to the design and development of the extension. contributions to the design and development of the extension.
Many people have made valuable comments and suggestions, including Many people have made valuable comments and suggestions, including
Rex Fernando, Eugene Kim, Danny McPherson, Dave Meyer, Pradosh Rex Fernando, Eugene Kim, Danny McPherson, Dave Meyer, Pradosh
Mohapatra, Keyur Patel, Robert Raszuk, Eric Rosen, Srihari Sangli, Mohapatra, Keyur Patel, Robert Raszuk, Eric Rosen, Srihari Sangli,
Dan Tappan, Mark Turner, Jeff Haas, Jay Borkenhagen, Mach Chen, Denis Dan Tappan, Mark Turner, Jeff Haas, Jay Borkenhagen, Mach Chen, Denis
Ovsienko, Carlos Pignataro and Meral Shirazipour. Ovsienko, Carlos Pignataro, Meral Shirazipour and Kathleen Moriarty.
10. References 10. References
10.1. Normative References 10.1. 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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
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[I-D.ietf-idr-add-paths-guidelines] [I-D.ietf-idr-add-paths-guidelines]
Uttaro, J., Francois, P., Patel, K., Haas, J., Simpson, Uttaro, J., Francois, P., Patel, K., Haas, J., Simpson,
A., and R. Fragassi, "Best Practices for Advertisement of A., and R. Fragassi, "Best Practices for Advertisement of
Multiple Paths in IBGP", draft-ietf-idr-add-paths- Multiple Paths in IBGP", draft-ietf-idr-add-paths-
guidelines-08 (work in progress), April 2016. guidelines-08 (work in progress), April 2016.
[I-D.ietf-idr-route-oscillation-stop] [I-D.ietf-idr-route-oscillation-stop]
Walton, D., Retana, A., Chen, E., and J. Scudder, "BGP Walton, D., Retana, A., Chen, E., and J. Scudder, "BGP
Persistent Route Oscillation Solutions", draft-ietf-idr- Persistent Route Oscillation Solutions", draft-ietf-idr-
route-oscillation-stop-02 (work in progress), April 2016. route-oscillation-stop-03 (work in progress), April 2016.
[I-D.pmohapat-idr-fast-conn-restore] [I-D.pmohapat-idr-fast-conn-restore]
Mohapatra, P., Fernando, R., Filsfils, C., and R. Raszuk, Mohapatra, P., Fernando, R., Filsfils, C., and R. Raszuk,
"Fast Connectivity Restoration Using BGP Add-path", draft- "Fast Connectivity Restoration Using BGP Add-path", draft-
pmohapat-idr-fast-conn-restore-03 (work in progress), pmohapat-idr-fast-conn-restore-03 (work in progress),
January 2013. January 2013.
[RFC3345] McPherson, D., Gill, V., Walton, D., and A. Retana, [RFC3345] McPherson, D., Gill, V., Walton, D., and A. Retana,
"Border Gateway Protocol (BGP) Persistent Route "Border Gateway Protocol (BGP) Persistent Route
Oscillation Condition", RFC 3345, DOI 10.17487/RFC3345, Oscillation Condition", RFC 3345, DOI 10.17487/RFC3345,
August 2002, <http://www.rfc-editor.org/info/rfc3345>. August 2002, <http://www.rfc-editor.org/info/rfc3345>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>.
[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,
DOI 10.17487/RFC4724, January 2007, DOI 10.17487/RFC4724, January 2007,
<http://www.rfc-editor.org/info/rfc4724>. <http://www.rfc-editor.org/info/rfc4724>.
Authors' Addresses Authors' Addresses
Daniel Walton Daniel Walton
Cumulus Networks Cumulus Networks
185 E. Dana Street 185 E. Dana Street
Mountain View, CA 94041 Mountain View, CA 94041
US US
Email: dwalton@cumulusnetworks.com Email: dwalton@cumulusnetworks.com
Alvaro Retana Alvaro Retana
Cisco Systems, Inc. Cisco Systems, Inc.
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