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Re: [multipathtcp] Consensus call on potential MPTCP proxy work

Joe Touch <touch@isi.edu> Wed, 19 April 2017 18:12 UTC

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To: mohamed.boucadair@orange.com, Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
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From: Joe Touch <touch@isi.edu>
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Date: Wed, 19 Apr 2017 11:11:58 -0700
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Subject: Re: [multipathtcp] Consensus call on potential MPTCP proxy work
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On 4/18/2017 10:46 PM, mohamed.boucadair@orange.com wrote:
> ...
>
> Using the SYN data as control information is the hazardous part.
>
> [Med] It isn’t for the for the simple reason that legacy Internet
> nodes will never receive a SYN with CPE-supplied data and that the TCP
> peer is known to process the supplied data. A Guard against
> misconfigurations is supported: echo in a SYN/ACK.
>

The idea of using a magic number to protect against miscommunication
virtually ensures that there will be reliable connections with errors.
That changes TCPs semantics.

Putting data in the SYN of TFO is permitted only because of previous state.

MPTCP doesn't have that state and so it is hazardous to put data in the
SYN.

I.e., if you want TFO-like performance, figure out how to use TFO. Period.

Joe

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