Hi Christian, What about MPTCP? It would be good to know what MPTCP does in this case? Also does having a different packet number space create problems, or is it just your personal preference?
Behcet On Thu, Oct 1, 2020 at 2:58 AM Christian Huitema <[email protected]> wrote: > I am not sure that the current "mpquic" draft is the right approach. > Specifically, I do not agree that having one packet number space per path > is the right approach. This contradicts the design of QUIC V1, in which > data sent on multiple paths shares a common packet number space. For > example, in QUIC V1, we can start a connection on one path, migrate to > another path, and keep the same packet number space throughout. I find that > a very nice property -- and also an essential property if we want to > support NAT rebinding. Handling multipath with a single number space > requires some book-keeping on the sender side to match acknowledgements and > sending paths, but we have working code for that. > > I am also not convinced that we properly understand the concept of "path". > There is very little in the QUIC V1 protocol that requires transmission > paths to be symmetric: any packet sent from a node to a valid address of > the peer will be accepted, provided the crypto works. The linkage such > requirement comes from the statement that a server starts directing traffic > to a validated path when it sees the client using the same pair of > addresses. This is an "implicit" linkage; I would expect that the first > role of a multipoint extension would be to replace that by an "explicit" > statement of preferences. > > I am worried that we have a set of unresolved security issues around > paths, largely linked to the requirement to support NAT rebinding. If we > support NAT, the IP headers must be outside the authentication envelope of > the crypto. There are plausible attacks in which the attacker splices a > cryptographically valid packet and a forged IP header. We have some > defensive heuristics, but if we study multipath I hope we will end up with > something better. > > -- Christian Huitema > On 9/30/2020 5:51 PM, Ian Swett wrote: > > Given the responses, can we narrow down the way forward(ideally on a > different thread) to directions that are less open-ended? I'll suggest > some options, but the chairs and/or ADs need to decide. > 1) No future work on multipath in the QUIC WG, in the belief the existing > connection migration functionality is sufficient. > 2) Adopt the existing draft as a starting point for QUIC multipath( > draft-deconinck-multipath-quic > <https://tools.ietf.org/html/draft-deconinck-multipath-quic>), with the > explicit goal of not expanding the scope of the document. > 3) Adopting multipath as a core QUIC WG deliverable. > > I favor #2, but these may not be the right options. Normally I'd say > people should work this out in person, but that doesn't seem viable at > the moment. I'm happy to set up a long(3-4+hr) Google Meet to discuss this > via videoconference if that helps move the discussion forward. > > Or we can form a design team, which typically takes O(3 months) to finish. > > Ian > > On Wed, Sep 30, 2020 at 3:15 PM Spencer Dawkins at IETF < > [email protected]> wrote: > >> Hi, Martin, >> >> Just a couple of thoughts here: >> >> On Wed, Sep 30, 2020 at 12:16 PM Martin Duke <[email protected]> >> wrote: >> >>> (Speaking as an individual) >>> >>> There is some back-and-forth as to whether these are useful cases are >>> not. I'll take it on faith, given the proponents, that there is a real hope >>> of deploying this. However, I share the desire to not have the WG fully >>> consumed by MP-QUIC for the foreseeable future. >>> >> >> That sounds right. I'm assuming that getting the core QUIC specifications >> published and doing any cleanup work necessary SHOULD/MUST take priority, >> in the BCP 14 sense of those words. >> >> As Lars' initial note said, I'd also like to see the manageability, >> applicability, and datagram extension working group drafts, already adopted >> by QUIC, moving forward. >> >> >>> I don't think the community has well-established solutions for many >>> problems in this space (e.g. scheduling). However, I think QUIC is a far >>> better platform for experimentation than the alternatives, and would >>> support a draft similar to draft-deconinck-multipath-quic >>> <https://tools.ietf.org/html/draft-deconinck-multipath-quic> that >>> provided the required protocol extensions to make that happen [1]. >>> >> >> I agree that scheduling is challenging - 3GPP is certainly spending time >> defining different strategies for behaviors, even in addition to the ones >> we described in >> https://datatracker.ietf.org/doc/draft-bonaventure-quic-atsss-overview/. >> >> And I agree that the QUIC protocol would be a better platform for >> experimentation than anything I can think of (other suggestions are, of >> course, welcome). >> >> >>> IIUC the hard, unsolved problems are common to all MP protocols, so I >>> don't think further research and future standards in this area are specific >>> to QUIC or appropriate for the QUIC Working Group. But experimental QUIC >>> extensions would accelerate this work, are appropriate for the WG, and may >>> get us to a place where we could confidently develop standards about it. >>> >> >> Targeting Experimental status for work in this area sounds like a fine >> plan to me (much better than not thinking about multicast in the IETF for a >> while longer). >> >> I know you have a variety of tools at your disposal to direct this work >> (MP-TCP was done in its own working group, for both Experimental and >> Standards-Track versions of the protocol specifications). Do the right >> thing, of course. >> >> What do you and Magnus need from members of the community, to help move >> forward on this? >> >> Best, >> >> Spencer >> >> >>> Martin Duke >>> >>> [1] I would prefer that this draft be Experimental, and have numerous >>> nits about the design that are not relevant to this thread. >>> >> >> >> >
