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Versions: 00 01 02 03 04 RFC 5543

Network Working Group              Hamid Ould-Brahim (Nortel Networks)
Internet Draft                             Don Fedyk (Nortel Networks)
Expiration Date: June 2009            Yakov Rekhter (Juniper Networks)
Intended Status: Proposed Standard

                   BGP Traffic Engineering Attribute

              draft-ietf-softwire-bgp-te-attribute-04.txt


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Abstract

   This document defines a new BGP attribute, 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.












1. 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 in RFC 2119 [RFC2119].


2. Introduction

   In certain cases (e.g., L1VPN [RFC5195]) it may be useful to augment
   VPN reachability information carried in BGP with the Traffic
   Engineering information.

   This document defines a new BGP attribute, 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 attribute are outside the scope
   of this document.


3. Traffic Engineering Attribute

   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], [RFC5307].

   The attribute contains one or more of the following:

       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 in Section 3.1.1 of [RFC3471].

   The Encoding field contains one of the values specified in Section
   3.1.1 of [RFC3471].

   The Reserved field SHOULD be set to 0 on transmit and MUST be ignored
   on receive.

   Maximum LSP 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.

       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       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 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 Interface MTU is encoded as a 2 octet integer.

   When the Switching Capability field is L2SC, there is no Switching
   Capability specific information field present.

   When the Switching Capability field is TDM, the Switching Capability
   specific information field includes Minimum LSP Bandwidth and an
   indication of whether the interface supports Standard or Arbitrary
   SONET/SDH.

       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  |
      +-+-+-+-+-+-+-+-+

   The 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 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.

   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 these routes
   share the same BGP Traffic Engineering attribute or not (see below).

   When the routes differ in other than the Traffic Engineering
   Attribute (e.g., differ in the set of Route Targets, and/or
   NEXT_HOP), use of 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 a single message.


6. IANA Considerations

   This document defines a new BGP attribute. 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
   in RFC 4271



8. Acknowledgements

   The authors would like to thank John Scudder and Jeffrey Haas for
   their review and comments.









9. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4201] Kompella, K., Rekhter, Y., Berger, L., "Link Bundling in
   MPLS Traffic Engineering (TE)", RFC 4201, October 2005<P>

   [RFC4271] Rekhter, Y., T. Li, Hares, S., "A Border Gateway Protocol 4
   (BGP-4)", RFC4271, January 2006.

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
   (GMPLS) Signaling Functional Description", RFC 3471, January 2003.

   [IEEE] IEEE, "IEEE Standard for Binary Floating-Point Arithmetic",
   Standard 754-1985, 1985 (ISBN 1-5593-7653-8).


10. Non-Normative References

   [RFC4203] Kompella, K., Rekhter, Y., "OSPF Extensions in Support of
   Generalized Multi-Protocol Label Switching (GMPLS)", RFC4203, October
   2005

   [RFC5307] Kompella, K., Rekhter, Y., "Intermediate System to
   Intermediate System (IS-IS) Extensions in Support of Generalized
   Multi-Protocol Label Switching (GMPLS)", RFC5307, October 2005

   [RFC5195] Ould-Brahim, H., Fedyk, D., Rekhter, Y., "BGP-Based Auto-
   Discovery for Layer-1 VPNs", RFC5195, June 2008


11. Author Information


   Hamid Ould-Brahim
   Nortel Networks
   Email: hbrahim@nortel.com

   Don Fedyk
   Nortel Networks
   Email: dwfedyk@nortel.com

   Yakov Rekhter
   Juniper Networks, Inc.
   email: yakov@juniper.com


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