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BGP Multipath in Inter-AS Option-B

Document Type Expired Internet-Draft (individual)
Expired & archived
Authors , Arjun Sreekantiah , Dhananjaya Rao , Keyur Patel
Last updated 2018-04-19 (Latest revision 2017-09-11)
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


By default, The Border Gateway Protocol, BGP only installs the best- path to the IP Routing Table. BGP multi-path is a well known feature that enables installation of multiple paths to the IP Routing Table. This is done to achieve load balancing while forwarding traffic. For a path to be eligible as a multi-path, certain criteria need to be fulfilled. Inter-AS VPNs are commonly deployed to span organizations across Service Provider boundaries. In this draft, we describe an issue relating to multi-path load balancing that can arise in an Option B Inter-AS Deployment. With the help of a representative topology, we illustrate the problem and then present two simple schemes as the solution to the problem. We also note as a matter of independent interest that the same underlying issue is applicable to deployments that employ next-hop-self behavior (implicit or explicit) downstream and the multi-path feature upstream.

Arjun Sreekantiah
Dhananjaya Rao
Keyur Patel

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)