I know that this subject line might be taken to be inflammatory, but no point in burying the lede.
The original charter for QUIC included multipath, partial reliability, and FEC. Multipath was definitely firmer than the others, but it was still aspirational. As part of a larger package deal, it seemed OK at the time. What has become clear to me over time is that there are only a small number of people who want to pursue multipath. And I don't know whether those people have common use cases or even if a single solution is appropriate for all of those use cases. Right now, it is not clear to me that we have the right combination of problem statements (or use cases), plausible solutions, and participants to successfully drive toward a design. I've followed the discussion recently and this has become increasingly apparent. The IETF processes for deciding whether to take on new work are designed to prove that there is a need for a standard. That need depends on proof of three things: supporting use cases, credible solutions, and interested participants. That process, by which I mean BoFs, is imperfect, but they are the best we have. And it looks like this working group is on a path to avoid that process. That would be a mistake. By coasting into a decision here, we risk confusing enthusiasm for QUIC as a whole for interest in this one feature. I appreciate that some people believe that there was an understanding reached on this topic. I know we've talked about this a number of times. But discussion was always about deferral in the past. We're now talking about concretely committing time to this. If the group had nothing else to do, then I'd be less concerned about the time being spent on this. I have no real interest, but I could go elsewhere. But QUICv1 is hardly done. We have more deployment experience to learn from, version negotiation, datagrams, performance tuning, and enough stuff to keep this community busy. If this community is not committed to building multipath capabilities, then forcing that upon them would be counterproductive. If the community is indeed committed, then a demonstration of that commitment should not be difficult to muster. Deciding whether the IETF should design a multipath QUIC needs to go to a BoF.
