draft-ietf-idr-link-bandwidth-03.txt   draft-ietf-idr-link-bandwidth-04.txt 
Network Working Group P. Mohapatra Network Working Group P. Mohapatra
Internet-Draft R. Fernando Internet-Draft R. Fernando
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: April 5, 2012 October 3, 2011 Expires: October 12, 2012 April 10, 2012
BGP Link Bandwidth Extended Community BGP Link Bandwidth Extended Community
draft-ietf-idr-link-bandwidth-03.txt draft-ietf-idr-link-bandwidth-04.txt
Abstract Abstract
This document describes an application of BGP extended communities This document describes an application of BGP extended communities
that allows a router to perform unequal cost load balancing. that allows a router to perform unequal cost load balancing.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 5, 2012. This Internet-Draft will expire on October 12, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . . 4 7. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
When a BGP speaker receives multiple paths from its internal peers, 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 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 it might be useful to provide the speaker with information that would
help it distribute the traffic unequally based on the bandwidth of help it distribute the traffic based on the bandwidth of the external
the external (DMZ) link. This document suggests that the external (DMZ) link. This document suggests that the external link bandwidth
link bandwidth be carried in the network using a new extended be carried in the network using a new extended community [RFC4360] -
community [RFC4360] - the link bandwidth extended community. the link bandwidth extended community.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Link Bandwidth Extended Community 2. Link Bandwidth Extended Community
When a BGP speaker receives a route from an external neighbor and When a BGP speaker receives a route from an external neighbor and
advertises this route (via IBGP) to internal neighbors, as part of advertises this route (via IBGP) to internal neighbors, as part of
this advertisement the router may carry the cost to reach the this advertisement the router may carry the cost to reach the
neighbor. The cost can be either configured per neighbor or derived external neighbor. The cost can be either configured per neighbor or
from the bandwidth of the link that connects the router to a directly derived from the bandwidth of the link that connects the router to a
connected external neighbor. This value is carried in the Link directly connected external neighbor. This value is carried in the
Bandwidth Extended Community. No more than one link bandwidth Link Bandwidth Extended Community. No more than one link bandwidth
extended community SHALL be attached to a route. Additionally, if a extended community SHALL be attached to a route. Additionally, if a
route is received with link bandwidth extended community and the BGP route is received with link bandwidth extended community and the BGP
speaker sets itself as next-hop while announcing that route to other speaker sets itself as next-hop while announcing that route to other
peers, the link bandwidth extended community should be removed. peers, the link bandwidth extended community should be removed.
The extended community is optional non-transitive. The value of the The extended community is optional non-transitive. The value of the
high-order octet of the extended Type Field is 0x40. The value of 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 the low-order octet of the extended type field for this community is
0x04. The value of the Global Administrator subfield in the Value 0x04. The value of the Global Administrator subfield in the Value
Field SHOULD represent the Autonomous System of the router that Field SHOULD represent the Autonomous System of the router that
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community, the receiver should not perform unequal cost load community, the receiver should not perform unequal cost load
balancing based on link bandwidths. balancing based on link bandwidths.
4. Acknowledgments 4. Acknowledgments
The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan The authors would like to thank Yakov Rekhter, Srihari Sangli and Dan
Tappan for proposing unequal cost load balancing as one possible Tappan for proposing unequal cost load balancing as one possible
application of the extended community attribute. application of the extended community attribute.
The authors would like to thank Bruno Decraene, Robert Raszuk, Joel The authors would like to thank Bruno Decraene, Robert Raszuk, Joel
Halpern, and Aleksi Suhonen for their useful comments and Halpern, Aleksi Suhonen, and Randy Bush for their useful comments and
discussions. discussions.
5. IANA Considerations 5. IANA Considerations
This document defines a specific application of the two-octet AS This document defines a specific application of the two-octet AS
specific extended community. IANA is requested to assign a sub- type specific extended community. IANA is requested to assign a sub- type
value of 0x04 for the link bandwidth extended community. value of 0x04 for the link bandwidth extended community.
Name Value Name Value
---- ----- ---- -----
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