Re: [multipathtcp] draft-boucadair-mptcp-plain-mode-07

Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> Fri, 01 July 2016 07:01 UTC

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From: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Date: Fri, 1 Jul 2016 09:01:01 +0200
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Subject: Re: [multipathtcp] draft-boucadair-mptcp-plain-mode-07
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Hello,
>
> In the paired MPTCP proxies mechanism, there is user's TCP session and there is also multipath TCP session. It is a TCP over TCP idea, correct?

No, there are three TCP connections in this scenario :

- one (regular) TCP connection between client and CPE
- one Multipath TCP connection between the CPE and the Concentrator
- one (regular) TCP connection between the Concentrator and the remote 
server

> As for TCP over TCP, the following page explains why an internal meltdown effect would take place due to the interaction between two leveled retransmission mechanisms.
> http://sites.inka.de/bigred/devel/tcp-tcp.html

This is a well known issue.

> Do we have solid solutions for this issue nowadays?

The solution is to terminate the TCP connections transparently. This is 
what most TCP optimisers used in mobile networks do already.


Olivier