Re: [Fwd: New Liaison Statement, "LS on need for Multi-Path QUIC for ATSSS"]

[Spencer Dawkins at IETF <[e-mail]>]

Hi, Martin,

On Wed, Apr 1, 2020 at 6:56 PM Martin Thomson <[e-mail]> wrote:

> If I read this liaison correctly, this is effectively a request to keep
> 3GPP in the loop.  The request to do multipath is more implied than
> anything else.  I think that the explicit request is fine.  The implicit
> one maybe less so.
>
> I suspect that work here would go faster if we had more input on the hard
> multipath problems.  That's not the spelling of the protocol (that's almost
> trivial, as demonstrated in proposals), but the assignment of different
> information elements paths that might have different characteristics.  What
> I heard in Zürich was that this was less of an engineering problem than a
> research one.
>
> I'd be interested in having active engagement from people who have use
> cases. Specifically, I would seek to learn whether this is truly a research
> question or whether there are simplifying assumptions that might make the
> problem tractable for some use cases.
>
> The more I think on this subject, the more that I think it was a mistake
> to charter to do multipath.  I don't believe that we properly answered the
> standard BoF questions with respect to this topic.
>

You rang? :-)

Multipath has been in the QUIC charter since the first proposed version
(see https://datatracker.ietf.org/doc/charter-ietf-quic/00-00/), at my
urging, because I couldn't imagine chartering a new transport protocol in
2016 without multipath, given that we'd had to retrofit that into both TCP
and SCTP. So this might have been a mistake, but it's not a recent one, and
I made it (and achieved IETF consensus, of course :-)

When we chartered QUIC, I don't think we had a clear picture of how much
MP-TCP was going to depend on use cases in order to justify deployment. I
think that now, if we know anything about multipath, we know that.

I agree that this could be a research topic (in at least one of two or
three existing research groups).

I note that 3GPP has been relying on MP-TCP for ATSSS, and I hope that we
might be able to better than that, for their use case.

But we definitely have some talking to do with them about their use case.

Best,

Spencer, who hopes Mirja told Magnus and Martin that they can ALWAYS blame
the previous AD ;-)

On Thu, Apr 2, 2020, at 01:15, Magnus Westerlund wrote:
> > QUIC WG,
> >
> > The IETF has received the attached Liasion statement (
> > https://datatracker.ietf.org/liaison/1678/) that is intended for the
> QUIC WG.
> > Please review it and the WG should considerd sending information to 3GPP
> as
> > requested at key points in the process of the multi-path
> extension/version of
> > QUIC.
> >
> > Cheers
> >
> > Magnus Westerlund
> > TSV AD
> >
> >
> > Attachments:
> > * Email.eml
> > * smime.p7s
>
>