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To: Juliusz Chroboczek <jch@irif.fr>, bloat <bloat@lists.bufferbloat.net>
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Date: Mon, 01 Apr 2024 22:33:13 +0200
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Subject: Re: [Bloat] The sad state of MP-TCP
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Juliusz Chroboczek via Bloat <bloat@lists.bufferbloat.net> writes:

> Unfortunately, MP-TCP does not replace TCP in Linux, it's implemented as
> a separate transport protocol.  That means that in order to use MP-TCP,
> every application needs to be patched to use PROT_MPTCP instead of
> PROT_TCP.  Go applications need to call SetMultipathTCP(true) on every
> net.Conn and every net.Listener.
>
> There should be a knob in the kernel to transparently replace TCP with
> MP-TCP, but I couldn't find one.

There is, sorta. Specifically, a BPF hook that can override the protocol
(added in kernel 6.6):

https://lore.kernel.org/all/cover.1692147782.git.geliang.tang@suse.com/

-Toke