Multipath TCP: an overview [LWN.net]

Multipath TCP: an overview

Posted Mar 27, 2013 9:03 UTC (Wed) by christophpaasch (subscriber, #54567)
In reply to: Multipath TCP: an overview by gylle
Parent article: Multipath TCP: an overview

If the paths have different delays (e.g., WiFi vs. 3G), the Head-of-line blocking is "fixed" by reinjecting the blocking segment on the faster subflow.

You can have a look at the scientific paper, which describes this mechanism:
http://inl.info.ucl.ac.be/publications/how-hard-can-it-be...

(Section 4.2)

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Multipath TCP: an overview

Posted Mar 27, 2013 11:46 UTC (Wed) by gylle (subscriber, #15057) [Link]

Thanks! That was what I was looking for. Quite a costly fix though.

Multipath TCP: an overview

Posted Mar 27, 2013 12:43 UTC (Wed) by christophpaasch (subscriber, #54567) [Link]

Costly, in terms of what?
Because we reinject the data on another subflow and thus use its bandwidth?

Multipath TCP: an overview

Posted Mar 27, 2013 12:45 UTC (Wed) by christophpaasch (subscriber, #54567) [Link]

Actually, I agree that the stack should reinject as few packets as possible to prevent wasting bandwidth.

But there won't ever be more than one reinjection per RTT of the fast subflow.