Re: [multipathtcp] potential MPTCP proxy charter item

Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be> Mon, 07 November 2016 07:50 UTC

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To: Alan Ford <alan.ford@gmail.com>
From: Olivier Bonaventure <Olivier.Bonaventure@uclouvain.be>
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Date: Mon, 7 Nov 2016 08:50:17 +0100
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Subject: Re: [multipathtcp] potential MPTCP proxy charter item
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Alan,

>>
>> Indeed, the same could apply for TCP, SCTP and probably any transport
>> protocol.
>
> Good, I’m glad we agree here :-)
>
>>> Why are you trying to make it a MPTCP option?
>>
>> The need comes from MPTCP. It could be defined as a TCP option instead
>> of an MPTCP option. I think that explicitly specifying a proxy node is
>> a useful feature that should be part of the transport protocol and not
>> tied to a specific application. We are less and less in a pure
>> end-to-end deployment model for the Internet and making those
>> transport proxies explicit would make sense.
>
> Why is it an /option/, however? When you are explicitly targeting a
> proxy node, surely the proxy is just as capable of pulling the data out
> of the payload here?
>

Because the addressing information that is used for the proxy is part of 
the control plane and not part of the bytestream. I think that it is 
very important from an architectural viewpoint to maintain a clean 
separation between the byte stream that is exchanged between the 
applications and all control information that should be placed inside 
options.

We explore the possibility of adding information in the bytestream for 
MPTCP and eventually decided to place all control information in 
options. If you look at HTTP, proxy-related information is part of the 
HTTP headers and not part of the payload. This is the same type of problem.


Olivier