Subject: [multipathtcp] Multipath congestion control

From: Mark Handley <[email-masked]>
Date: Mon, 27 Jul 2009 09:07:44 +0100

We finished a paper on Saturday on how to link the congestion
controllers of the subflows in a multipath TCP session.  Basically we:

 - link the increases of the subflows to the *total* window (not the
subflow window) to achieve reasonable resource pooling in the network
 - compensate for differing RTTs, which would otherwise cause a
multipath flow to do worse than a single-path flow.
 - use the additive increase constant as an aggressiveness controller,
to ensure we do at least as well (in terms of rate) as a single-path
flow, while ensuring we impose no more load on any single bottleneck
than a single-path TCP would.

I'm sure this won't be the last word on multi-path congestion control,
but it does show that there is a conservative solution that works well
and is safe enough for deployment.  Costin Raiciu will talk briefly
about this problem and how to solve it on Thursday.  As the paper is
under anonymous submission, I'm reluctant to send it directly to this
list, but if you want a copy privately, please send me email.

 - Mark