draft-ietf-idr-link-bandwidth-00.txt   draft-ietf-idr-link-bandwidth-01.txt 
Network Working Group P. Mohapatra Network Working Group P. Mohapatra
Internet-Draft Cisco Systems Internet-Draft R. Fernando
Intended status: Standards Track R. Fernando Intended status: Standards Track Cisco Systems
Expires: October 23, 2009 Juniper Networks Expires: August 28, 2010 February 24, 2010
April 21, 2009
BGP Link Bandwidth Extended Community 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 Status of this Memo
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Copyright Notice 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. 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
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Abstract 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 This document may contain material from IETF Documents or IETF
that allows a router to perform unequal cost load balancing. 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 Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3 2. Link Bandwidth Extended Community . . . . . . . . . . . . . . . 3
3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 4 3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 3
4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . . . . . . . . . . . . 4
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 cost of the help it distribute the traffic unequally based on the cost of the
external (DMZ) link. This document suggests that the external link external (DMZ) link. This document suggests that the external link
bandwidth be carried in the network using a new extended community bandwidth be carried in the network using a new extended community
[RFC4360] - the link bandwidth extended community. [RFC4360] - the link bandwidth extended community.
skipping to change at page 3, line 31 skipping to change at page 3, line 31
2. Link Bandwidth Extended Community 2. Link Bandwidth Extended Community
When a BGP speaker receives a route from a directly connected When a BGP speaker receives a route from a directly connected
external neighbor (the external neighbor that is one IP hop away) and external neighbor (the external neighbor that is one IP hop away) 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 bandwidth of the link this advertisement the router may carry the bandwidth of the link
that connects the router with the external neighbor. The bandwidth that connects the router with the external neighbor. The bandwidth
of such a link is carried in the Link Bandwidth Community. The of such a link is carried in the Link Bandwidth Community. The
community is optional non-transitive. A border router MUST strip the community is optional non-transitive. A border router MUST strip the
link bandwidth community from a route when it advertises the route to link bandwidth community from a route when it advertises the route to
an external neighbor. 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
It is noteworthy that the bandwidth carried in the Link Bandwidth extended type field for this community is 0x04. The value of the
extended community is the configured bandwidth of the EBGP link. It Global Administrator subfield in the Value Field SHOULD represent the
does not depend on the amount of traffic transiting that link. Autonomous System of the router that attaches the Link Bandwidth
Community. If four octet AS numbering scheme is used [RFC4893],
The value of the high-order octet of the extended Type Field is 0x40. AS_TRANS should be used in the Global Administrator subfield. The
The value of the low-order octet of the extended type field for this bandwidth of the link is expressed as 4 octets in IEEE floating point
community is 0x04. format, units being bytes per second. It is carried in the Local
Administrator subfield of the Value Field.
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 3. Deployment Considerations
This document proposes to use the Link Bandwidth extended community The usage of this community is restricted to the cases where BGP
for the purpose of load balancing in the following two scenarios. multipath can be safely deployed. In other words, the IGP distance
The first scenario is when the candidate paths are identical until between the load balancing router and the exit points should be the
and including the IGP distance step in the BGP decision process. The same. Alternatively, the path between the load sharing router and
second scenario is when the traffic goes via a tunneled network, in the exit points could be label switched. If there are multiple paths
which case the candidate paths are identical for all steps before the to reach a destination and if only some of them have link bandwidth
IGP distance step in the BGP decision process. Use of this community community, the receiver should not perform unequal cost load
for other scenarios is outside the scope of this document. balancing based on link bandwidths.
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 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.
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
skipping to change at page 5, line 20 skipping to change at page 5, line 17
Pradosh Mohapatra Pradosh Mohapatra
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
USA USA
Phone: Phone:
Email: pmohapat@cisco.com Email: pmohapat@cisco.com
Rex Fernando Rex Fernando
Juniper Networks Cisco Systems
1194 N. Mathilda Ave 170 W. Tasman Drive
Sunnyvale, CA 94089 San Jose, CA 95134
USA USA
Phone: Phone:
Email: rex@juniper.net Email: rex@cisco.com
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