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Network Working Group                                     H. Ould-BrahimRequest for Comments: 5543                               Nortel NetworksCategory: Standards Track                                       D. Fedyk                                                          Alcatel-Lucent                                                              Y. Rekhter                                                        Juniper Networks                                                                May 2009BGP Traffic Engineering AttributeStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (c) 2009 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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   This document defines a new BGP attribute, the Traffic Engineering   attribute, that enables BGP to carry Traffic Engineering information.   The scope and applicability of this attribute currently excludes its   use for non-VPN reachability information.Ould-Brahim, et al.         Standards Track                     [Page 1]

RFC 5543                    BGP TE Attribute                    May 20091.  Introduction   In certain cases (e.g., Layer-1 VPNs (L1VPNs) [RFC5195]), it may be   useful to augment the VPN reachability information carried in BGP   with Traffic Engineering information.   This document defines a new BGP attribute, the Traffic Engineering   attribute, that enables BGP [RFC4271] to carry Traffic Engineering   information.Section 4 of [RFC5195] describes one possible usage of this   attribute.   The scope and applicability of this attribute currently excludes its   use for non-VPN reachability information.   Procedures for modifying the Traffic Engineering attribute, when   re-advertising a route that carries such an attribute, are outside   the scope of this document.2.  Specification of Requirements   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described inRFC 2119 [RFC2119].3.  Traffic Engineering Attribute   The Traffic Engineering attribute is an optional, non-transitive BGP   attribute.   The information carried in this attribute is identical to what is   carried in the Interface Switching Capability Descriptor, as   specified in [RFC4203] and [RFC5307].   The attribute contains one or more of the following:Ould-Brahim, et al.         Standards Track                     [Page 2]

RFC 5543                    BGP TE Attribute                    May 2009       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      | Switching Cap |   Encoding    |           Reserved            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 0              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 1              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 2              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 3              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 4              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 5              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 6              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Max LSP Bandwidth at priority 7              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |             Switching Capability specific information         |      |                           (variable)                          |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   The Switching Capability (Switching Cap) field contains one of the   values specified inSection 3.1.1 of [RFC3471].   The Encoding field contains one of the values specified inSection3.1.1 of [RFC3471].   The Reserved field SHOULD be set to 0 on transmit and MUST be ignored   on receive.   Maximum LSP (Label Switched Path) Bandwidth is encoded as a list of   eight 4-octet fields in the IEEE floating point format [IEEE], with   priority 0 first and priority 7 last.  The units are bytes (not   bits!)  per second.   The content of the Switching Capability specific information field   depends on the value of the Switching Capability field.   When the Switching Capability field is PSC-1, PSC-2, PSC-3, or PSC-4,   the Switching Capability specific information field includes Minimum   LSP Bandwidth and Interface MTU.Ould-Brahim, et al.         Standards Track                     [Page 3]

RFC 5543                    BGP TE Attribute                    May 2009       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Minimum LSP Bandwidth                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |           Interface MTU       |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE   floating point format.  The units are bytes (not bits!) per second.   Interface MTU is encoded as a 2-octet integer.   When the Switching Capability field is Layer-2 Switch Capable (L2SC),   there is no Switching Capability specific information field present.   When the Switching Capability field is Time-Division-Multiplex (TDM)   capable, the Switching Capability specific information field includes   Minimum LSP Bandwidth and an indication of whether the interface   supports Standard or Arbitrary SONET/SDH (Synchronous Optical   Network / Synchronous Digital Hierarchy).       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                  Minimum LSP Bandwidth                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |   Indication  |      +-+-+-+-+-+-+-+-+   Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE   floating point format.  The units are bytes (not bits!) per second.   The indication of whether the interface supports Standard or   Arbitrary SONET/SDH is encoded as 1 octet.  The value of this octet   is 0 if the interface supports Standard SONET/SDH, and 1 if the   interface supports Arbitrary SONET/SDH.   When the Switching Capability field is Lambda Switch Capable (LSC),   there is no Switching Capability specific information field present.4.  Implication on Aggregation   Routes that carry the Traffic Engineering attribute have additional   semantics that could affect traffic-forwarding behavior.  Therefore,   such routes SHALL NOT be aggregated unless they share identical   Traffic Engineering attributes.Ould-Brahim, et al.         Standards Track                     [Page 4]

RFC 5543                    BGP TE Attribute                    May 2009   Constructing the Traffic Engineering attribute when aggregating   routes with identical Traffic Engineering attributes follows the   procedure of [RFC4201].5.  Implication on Scalability   The use of the Traffic Engineering attribute does not increase the   number of routes, but may increase the number of BGP Update messages   required to distribute the routes, depending on whether or not these   routes share the same BGP Traffic Engineering attribute (see below).   When the routes differ other than in the Traffic Engineering   attribute (e.g., differ in the set of Route Targets and/or NEXT_HOP),   use of the Traffic Engineering attribute has no impact on the number   of BGP Update messages required to carry the routes.  There is also   no impact when routes share all other attribute information and have   an aggregated or identical Traffic Engineering attribute.  When   routes share all other attribute information and have different   Traffic Engineering attributes, routes must be distributed in   per-route BGP Update messages, rather than in a single message.6.  IANA Considerations   This document defines a new BGP attribute, Traffic Engineering.  This   attribute is optional and non-transitive.7.  Security Considerations   This extension to BGP does not change the underlying security issues   currently inherent in BGP.  BGP security considerations are discussed   inRFC 4271.8.  Acknowledgements   The authors would like to thank John Scudder and Jeffrey Haas for   their review and comments.9.  References9.1.  Normative References   [IEEE]    IEEE, "IEEE Standard for Binary Floating-Point Arithmetic",             Standard 754-1985, 1985 (ISBN 1-5593-7653-8).   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate             Requirement Levels",BCP 14,RFC 2119, March 1997.Ould-Brahim, et al.         Standards Track                     [Page 5]

RFC 5543                    BGP TE Attribute                    May 2009   [RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label             Switching (GMPLS) Signaling Functional Description",RFC3471, January 2003.   [RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling in             MPLS Traffic Engineering (TE)",RFC 4201, October 2005.   [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border             Gateway Protocol 4 (BGP-4)",RFC 4271, January 2006.9.2.  Informative References   [RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions in             Support of Generalized Multi-Protocol Label Switching             (GMPLS)",RFC 4203, October 2005.   [RFC5195] Ould-Brahim, H., Fedyk, D., and Y. Rekhter, "BGP-Based             Auto-Discovery for Layer-1 VPNs",RFC 5195, June 2008.   [RFC5307] Kompella, K., Ed., and Y. Rekhter, Ed., "IS-IS Extensions             in Support of Generalized Multi-Protocol Label Switching             (GMPLS)",RFC 5307, October 2008.Authors' Addresses   Hamid Ould-Brahim   Nortel Networks   EMail: hbrahim@nortel.com   Don Fedyk   Alcatel-Lucent   EMail: donald.fedyk@alcatel-lucent.com   Phone: 978-467-5645   Yakov Rekhter   Juniper Networks, Inc.   EMail: yakov@juniper.netOuld-Brahim, et al.         Standards Track                     [Page 6]