Network Working Group A. Retana Internet-Draft A. Kapoor Intended status: Informational K. Patel Expires: April 24, 2014 Cisco Systems, Inc. October 21, 2013 Use of the Cost Community to carry the Accumulated IGP Metric draft-retana-idr-aigp-cost-community-00 Abstract This document explains the use of the Cost Community to flexibly carry the Accumulated IGP Metric. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 24, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Retana, et al. Expires April 24, 2014 [Page 1] Internet-Draft Cost Community for AIGP October 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2 3. Use of the Cost Community to carry the AIGP . . . . . . . . . 2 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 7.1. Normative References . . . . . . . . . . . . . . . . . . 3 7.2. Informative References . . . . . . . . . . . . . . . . . 3 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction The Accumulated IGP Metric (AIGP) Attribute [I-D.ietf-idr-aigp] has been defined with the purpose of carrying an AIGP. The attribute is used in the BGP selection process before the tie braking procedures [RFC4271], effectively after the LOCAL_PREF comparison. The Cost Community [I-D.ietf-idr-custom-decision] can provide a flexible mechanism to carry the AIGP. It can se used both at a different point in the selection process, or as a direct replacement for the AIGP attribute in networks that don't fully support it. 2. Requirements Language 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 [RFC2119]. 3. Use of the Cost Community to carry the AIGP The applicability and procedures defined in [I-D.ietf-idr-aigp] for originating and modifying the AIGP value are not changed in this document. The value is used as the Cost of the Cost Community. The Point of Insertion (POI) can be set to any of the values defined in [I-D.ietf-idr-custom-decision]. Note that the use of the LOCAL_PREF POI is equivalent to using the AIGP Attribute in routers that don't support it. If the Cost Community is used to carry the AIGP velue, then the AIGP Attribute SHOULD NOT be used. If used, then the high-order bit of the Community-ID MUST be set in a Cost Community with a POI of AIGP to avoid an inconsistent selection process. Note that this operation doesn't preclude using a Cost Community with a Cost of the AIGP at a different POI. Retana, et al. Expires April 24, 2014 [Page 2] Internet-Draft Cost Community for AIGP October 2013 4. Security Considerations This document explains the use of the Cost Community to provide flexibility in the application of routing policy related to the accumulated IGP metric of a route. As such, it does not introduce new security risks than the ones considered in [I-D.ietf-idr-custom-decision] or [I-D.ietf-idr-aigp]. 5. IANA Considerations This document has no IANA actions. 6. Acknowledgements TBD 7. References 7.1. Normative References [I-D.ietf-idr-aigp] Mohapatra, P., Fernando, R., Rosen, E., and J. Uttaro, "The Accumulated IGP Metric Attribute for BGP", draft- ietf-idr-aigp-10 (work in progress), May 2013. [I-D.ietf-idr-custom-decision] Retana, A. and R. White, "BGP Custom Decision Process", draft-ietf-idr-custom-decision-03 (work in progress), May 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. Authors' Addresses Alvaro Retana Cisco Systems, Inc. 7025 Kit Creek Rd. Research Triangle Park, NC 27709 USA Email: aretana@cisco.com Retana, et al. Expires April 24, 2014 [Page 3] Internet-Draft Cost Community for AIGP October 2013 Anoop Kapur Cisco Systems, Inc. 170 Tasman Drive San Jose, CA 95134 USA Email: ankapoor@cisco.com Keyur Patel Cisco Systems, Inc. 170 Tasman Drive San Jose, CA 95134 USA Email: keyupate@cisco.com Retana, et al. Expires April 24, 2014 [Page 4]