BGP Link Bandwidth Extended Community
draft-ietf-idr-link-bandwidth-05
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
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Authors | Prodosh Mohapatra , Rex Fernando | ||
Last updated | 2012-11-05 | ||
Replaces | draft-rfernando-idr-link-bandwidth | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Additional resources | Mailing list discussion | ||
Stream | WG state | WG Document | |
Document shepherd | (None) | ||
IESG | IESG state | I-D Exists | |
Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | (None) | ||
Send notices to | (None) |
draft-ietf-idr-link-bandwidth-05
Network Working Group P. Mohapatra Internet-Draft R. Fernando Intended status: Standards Track Cisco Systems Expires: May 9, 2013 November 5, 2012 BGP Link Bandwidth Extended Community draft-ietf-idr-link-bandwidth-05.txt Abstract This document describes an application of BGP extended communities that allows a router to perform unequal cost load balancing. 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 May 9, 2013. Copyright Notice Copyright (c) 2012 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November Mohapatra & Fernando Expires May 9, 2013 [Page 1] Internet-Draft Link Bandwidth November 2012 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3 3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 7. Normative References . . . . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Mohapatra & Fernando Expires May 9, 2013 [Page 2] Internet-Draft Link Bandwidth November 2012 1. Introduction When a BGP speaker receives multiple paths from its internal peers, it could select more than one path to send traffic to. In doing so, it might be useful to provide the speaker with information that would help it distribute the traffic based on the bandwidth of the external (DMZ) link. This document suggests that the external link bandwidth be carried in the network using a new extended community [RFC4360] - the link bandwidth extended community. 1.1. 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 RFC 2119 [RFC2119]. 2. Link Bandwidth Extended Community When a BGP speaker receives a route from an external neighbor and advertises this route (via IBGP) to internal neighbors, as part of this advertisement the router may carry the cost to reach the external neighbor. The cost can be either configured per neighbor or derived from the bandwidth of the link that connects the router to a directly connected external neighbor. This value is carried in the Link Bandwidth Extended Community. No more than one link bandwidth extended community SHALL be attached to a route. Additionally, if a route is received with link bandwidth extended community and the BGP speaker sets itself as next-hop while announcing that route to other peers, the link bandwidth extended community should be removed. The extended community is optional non-transitive. The value of the high-order octet of the extended Type Field is 0x40. The value of the low-order octet of the extended type field for this community is 0x04. The value of the Global Administrator subfield in the Value Field SHOULD represent the Autonomous System of the router that attaches the Link Bandwidth Community. If four octet AS numbering scheme is used [RFC4893], AS_TRANS should be used in the Global Administrator subfield. The bandwidth of the link is expressed as 4 octets in IEEE floating point format, units being bytes (not bits!) per second. It is carried in the Local Administrator subfield of the Value Field. 3. Deployment Considerations The usage of this community is restricted to the cases where BGP multipath can be safely deployed. In other words, the IGP distance Mohapatra & Fernando Expires May 9, 2013 [Page 3] Internet-Draft Link Bandwidth November 2012 between the load balancing router and the exit points should be the same. Alternatively, the path between the load sharing router and the exit points could be tunneled. If there are multiple paths to reach a destination and if only some of them have link bandwidth community, the receiver should not perform unequal cost load balancing based on link bandwidths. 4. Acknowledgments The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan Tappan for proposing unequal cost load balancing as one possible application of the extended community attribute. The authors would like to thank Bruno Decraene, Robert Raszuk, Joel Halpern, Aleksi Suhonen, and Randy Bush for their useful comments and discussions. 5. IANA Considerations This document defines a specific application of the two-octet AS specific extended community. IANA is requested to assign a sub- type value of 0x04 for the link bandwidth extended community. Name Value ---- ----- non-transitive Link Bandwidth Ext. Community 0x4004 6. Security Considerations There are no additional security risks introduced by this design. 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, February 2006. [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS Number Space", RFC 4893, May 2007. Mohapatra & Fernando Expires May 9, 2013 [Page 4] Internet-Draft Link Bandwidth November 2012 Authors' Addresses Pradosh Mohapatra Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Phone: Email: pmohapat@cisco.com Rex Fernando Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Phone: Email: rex@cisco.com Mohapatra & Fernando Expires May 9, 2013 [Page 5]