--- 1/draft-ietf-idr-link-bandwidth-00.txt 2010-02-24 21:10:46.000000000 +0100 +++ 2/draft-ietf-idr-link-bandwidth-01.txt 2010-02-24 21:10:46.000000000 +0100 @@ -1,80 +1,85 @@ Network Working Group P. Mohapatra -Internet-Draft Cisco Systems -Intended status: Standards Track R. Fernando -Expires: October 23, 2009 Juniper Networks - April 21, 2009 +Internet-Draft R. Fernando +Intended status: Standards Track Cisco Systems +Expires: August 28, 2010 February 24, 2010 BGP Link Bandwidth Extended Community - draft-ietf-idr-link-bandwidth-00.txt + draft-ietf-idr-link-bandwidth-01.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 to IETF in full conformance with the - provisions of BCP 78 and BCP 79. This document may contain material - from IETF Documents or IETF Contributions published or made publicly - available before November 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. + provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on October 23, 2009. + This Internet-Draft will expire on August 28, 2010. Copyright Notice - Copyright (c) 2009 IETF Trust and the persons identified as the + Copyright (c) 2010 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 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 + 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 BSD License. - This document describes an application of BGP extended communities - that allows a router to perform unequal cost load balancing. + This document may contain material from IETF Documents or IETF + Contributions published or made publicly available before November + 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 . . . . . . . . . . . . . . . . . . . 4 + 3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 7. Normative References . . . . . . . . . . . . . . . . . . . . . 4 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 4 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 unequally based on the cost 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. @@ -88,54 +93,41 @@ 2. Link Bandwidth Extended Community When a BGP speaker receives a route from a directly connected external neighbor (the external neighbor that is one IP hop away) and advertises this route (via IBGP) to internal neighbors, as part of this advertisement the router may carry the bandwidth of the link that connects the router with the external neighbor. The bandwidth of such a link is carried in the Link Bandwidth Community. The community is optional non-transitive. A border router MUST strip the link bandwidth community from a route when it advertises the route to - an external neighbor. - - It is noteworthy that the bandwidth carried in the Link Bandwidth - extended community is the configured bandwidth of the EBGP link. It - does not depend on the amount of traffic transiting that link. - - 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 per second. It is carried in the - Local Administrator subfield of the Value Field. + an external neighbor. 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 per second. It is carried in the Local + Administrator subfield of the Value Field. 3. Deployment Considerations - This document proposes to use the Link Bandwidth extended community - for the purpose of load balancing in the following two scenarios. - The first scenario is when the candidate paths are identical until - and including the IGP distance step in the BGP decision process. The - second scenario is when the traffic goes via a tunneled network, in - which case the candidate paths are identical for all steps before the - IGP distance step in the BGP decision process. Use of this community - for other scenarios is outside the scope of this document. - - 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. + The usage of this community is restricted to the cases where BGP + multipath can be safely deployed. In other words, the IGP distance + 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 label switched. 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. 5. IANA Considerations This document defines a specific application of the two-octet AS @@ -166,17 +158,17 @@ Pradosh Mohapatra Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Phone: Email: pmohapat@cisco.com Rex Fernando - Juniper Networks - 1194 N. Mathilda Ave - Sunnyvale, CA 94089 + Cisco Systems + 170 W. Tasman Drive + San Jose, CA 95134 USA Phone: - Email: rex@juniper.net + Email: rex@cisco.com