[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-rfernando-idr-link-bandwidth) 00 01 02 03 04 05 06 07

Network Working Group                                       P. Mohapatra
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-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.

   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 August 28, 2010.

Copyright Notice

   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
   (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



Mohapatra & Fernando     Expires August 28, 2010                [Page 1]


Internet-Draft               Link Bandwidth                February 2010


   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 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 . . . . . . . . . . . . . . . . . . . 3
   4.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 4























Mohapatra & Fernando     Expires August 28, 2010                [Page 2]


Internet-Draft               Link Bandwidth                February 2010


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.

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 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.  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

   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



Mohapatra & Fernando     Expires August 28, 2010                [Page 3]


Internet-Draft               Link Bandwidth                February 2010


   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
   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 August 28, 2010                [Page 4]


Internet-Draft               Link Bandwidth                February 2010


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 August 28, 2010                [Page 5]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/