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Multipath TCP: an overview

Multipath TCP: an overview

Posted Mar 27, 2013 14:47 UTC (Wed) by christophpaasch (subscriber, #54567)
In reply to: Multipath TCP: an overview by nhorman
Parent article: Multipath TCP: an overview

An MPTCP-api is standardized in [1].

Yes, it could be useful for some applications to have better control on the paths being used. But, this assumes that applications actually know what they want... ;)

Right now, the implementation automatically creates a full mesh among the availabe IP-addresses on the client and the server.
More heuristics on when to create and destroy additional subflows are still under research.

Concerning your use-case where one wants to push more traffic on WiFi than 3G:
The coupled congestion control RFC 6356 [2] takes care about the congestion-windows of each subflow. In such a way, that traffic is pushed away from congested links to the non-congested ones. Additionally, it makes sure that MPTCP is fair to regular TCP flows across shared bottleneck links.

[1] https://datatracker.ietf.org/doc/draft-ietf-mptcp-api/
[2] https://datatracker.ietf.org/doc/rfc6356/


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Multipath TCP: an overview

Posted Apr 1, 2013 20:55 UTC (Mon) by cesarb (subscriber, #6266) [Link]

It is not "more traffic on wifi". If your 3G is metered and you are connected to wifi, _all_ traffic should be on wifi.

Multipath TCP: an overview

Posted Apr 1, 2013 21:08 UTC (Mon) by christophpaasch (subscriber, #54567) [Link]

The protocol allows to not use 3G for data-traffic with the "backup-flag" (MP_PRIO-option in RFC 6824).

Or, it is also possible to simply not open up a subflow across 3G and only create it after the phone lost the WiFi connection. MPTCP supports break-before-make scenarios.

It is simply a question of instructing the kernel to do one or the other through some kind of configuration interface (may it be sockopts, sysctl,...)

Multipath TCP: an overview

Posted Apr 1, 2013 22:11 UTC (Mon) by marcH (subscriber, #57642) [Link]

Just FYI: my home Wifi is routed to... a 3G, metered connection.

Far from ideal, but less and less unusual:

https://www.google.ie/search?q=3g+hotspot

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