Re: Multipath (was: Re: Re-chartering for extension work)

[Olivier Bonaventure <[e-mail]>]

Dear Mirja,

>  
> As Tommy said, migration is already the first half of multipath support for QUIC. So I expect it will be easier to add it to QUIC than it was for TCP.

The main benefit of QUIC is that we do not need to take middleboxes into account and can reason about the transport layer directly. 

> I would at least be curious to spend some time on figuring out how much (or how less) effort it would be. Maybe there is also another step before going to full multipath support that could support the handover use case better, e.g. sending redundant data on multi paths or something. I think it worth think about it.


Please don’t do that. With QUIC,  have a unique opportunity to design an architecturally clean and easily deployable multipath transport protocol. We should not pollute this design with hacks and short term solutions that have been included in too many Internet protocols for various reasons. 

> However, while I would like to see this discussion starting now, I think it’s fine to wait for adoption of any draft until v1 is done.

As already explained in previous emails, Quentin De Coninck has leveraged all the lessons learned from Multipath TCP in a Multipath QUIC design that has evolved in parallel with the standardisation work of QUIC v1. The initial design was described in

https://multipath-quic.org/conext17-deconinck.pdf <https://multipath-quic.org/conext17-deconinck.pdf>  and in https://www.ietf.org/archive/id/draft-deconinck-multipath-quic-00.txt <https://www.ietf.org/archive/id/draft-deconinck-multipath-quic-00.txt>

There was a running implementation on top of quic-go that is available from https://multipath-quic.org <https://multipath-quic.org/>

The draft has evolved several times on https://datatracker.ietf.org/doc/draft-deconinck-quic-multipath/ <https://datatracker.ietf.org/doc/draft-deconinck-quic-multipath/> 

The recent draft has been implemented on top of picoquic and was released on pquic.org <http://pquic.org/> 

Quentin has studied these designs in details with many experiments, both in the lab and in the wild on smartphones. He’d be ready to present this in details to the working group if if eventually decides to work on the multipath item of its charter. I would encourage the working group members to start to read the last version of Quentin’s draft and provide comments.


Best regards,


Olivier


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