draft-ietf-idr-add-paths-11.txt   draft-ietf-idr-add-paths-12.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: April 9, 2016 E. Chen Expires: May 7, 2016 E. Chen
Cisco Systems, Inc. Cisco Systems, Inc.
J. Scudder J. Scudder
Juniper Networks Juniper Networks
October 7, 2015 November 4, 2015
Advertisement of Multiple Paths in BGP Advertisement of Multiple Paths in BGP
draft-ietf-idr-add-paths-11 draft-ietf-idr-add-paths-12
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 April 9, 2016. This Internet-Draft will expire on May 7, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Specification of Requirements . . . . . . . . . . . . . . 2 1.1. Specification of Requirements . . . . . . . . . . . . . . 2
2. How to Identify a Path . . . . . . . . . . . . . . . . . . . 3 2. How to Identify a Path . . . . . . . . . . . . . . . . . . . 3
3. Extended NLRI Encodings . . . . . . . . . . . . . . . . . . . 3 3. Extended NLRI Encodings . . . . . . . . . . . . . . . . . . . 3
4. ADD-PATH Capability . . . . . . . . . . . . . . . . . . . . . 4 4. ADD-PATH Capability . . . . . . . . . . . . . . . . . . . . . 3
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Applications . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Applications . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Deployment Considerations . . . . . . . . . . . . . . . . . . 6 7. Deployment Considerations . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
11.1. Normative References . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . 6
11.2. Informative References . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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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in such a way that the BGP speaker is able to use the (prefix, path in such a way that the BGP speaker is able to use the (prefix, path
identifier) to uniquely identify a path advertised to a neighbor. A identifier) to uniquely identify a path advertised to a neighbor. A
BGP speaker that re-advertises a route MUST generate its own Path BGP speaker that re-advertises a route MUST generate its own Path
Identifier to be associated with the re-advertised route. A BGP Identifier to be associated with the re-advertised route. A BGP
speaker that receives a route SHOULD NOT assume that the identifier speaker that receives a route SHOULD NOT assume that the identifier
carries any particular semantics; it SHOULD be treated as an opaque carries any particular semantics; it SHOULD be treated as an opaque
value. value.
3. Extended NLRI Encodings 3. Extended NLRI Encodings
In order to carry the Path Identifier in an UPDATE message, the In order to carry the Path Identifier in an UPDATE message, the NLRI
existing NLRI encodings are extended by prepending the Path encoding MUST be extended by prepending the Path Identifier field,
Identifier field, which is of four-octets. which is of four-octets.
For example, the NLRI encodings specified in [RFC4271] and [RFC4760]
are extended as the following:
+--------------------------------+
| Path Identifier (4 octets) |
+--------------------------------+
| Length (1 octet) |
+--------------------------------+
| Prefix (variable) |
+--------------------------------+
and the NLRI encoding specified in [RFC3107] is extended as the For example, the NLRI encoding specified in [RFC4271] is extended as
following: the following:
+--------------------------------+ +--------------------------------+
| Path Identifier (4 octets) | | Path Identifier (4 octets) |
+--------------------------------+ +--------------------------------+
| Length (1 octet) | | Length (1 octet) |
+--------------------------------+ +--------------------------------+
| Label (3 octets) |
+--------------------------------+
| ... |
+--------------------------------+
| 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 Section 5.
Operation section.
4. ADD-PATH Capability 4. ADD-PATH Capability
The ADD-PATH Capability is a new BGP capability [RFC5492]. 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:
+------------------------------------------------+ +------------------------------------------------+
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11. References 11. References
11.1. Normative References 11.1. 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>.
[RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in
BGP-4", RFC 3107, DOI 10.17487/RFC3107, May 2001,
<http://www.rfc-editor.org/info/rfc3107>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>. <http://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, "Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007, DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>. <http://www.rfc-editor.org/info/rfc4760>.
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[I-D.ietf-idr-add-paths-guidelines] [I-D.ietf-idr-add-paths-guidelines]
Uttaro, J., Francois, P., Patel, K., Mohapatra, P., Haas, Uttaro, J., Francois, P., Patel, K., Mohapatra, P., Haas,
J., Simpson, A., and R. Fragassi, "Best Practices for J., Simpson, A., and R. Fragassi, "Best Practices for
Advertisement of Multiple Paths in IBGP", draft-ietf-idr- Advertisement of Multiple Paths in IBGP", draft-ietf-idr-
add-paths-guidelines-07 (work in progress), December 2014. add-paths-guidelines-07 (work in progress), December 2014.
[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-00 (work in progress), February route-oscillation-stop-01 (work in progress), October
2015. 2015.
[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
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