> On 20. jul. 2016, at 09.22, Anna Brunstrom <[email protected]> wrote: > > On 2016-07-19 17:59, Michael Welzl wrote: > >>> On 19. jul. 2016, at 17.52, Joe Touch <[email protected]> wrote: >>> >>> >>> >>> On 7/19/2016 8:49 AM, Michael Welzl wrote: >>>>> On 19. jul. 2016, at 17.40, Joe Touch <[email protected]> wrote: >>>>> >>>>> >>>>> >>>>> On 7/19/2016 5:27 AM, Michael Welzl wrote: >>>>>> Thanks - I agree, it’s on the agenda for tomorrow’s MPTCP session, and >>>>>> TAPS is the day after, which fits nicely. >>>>>> >>>>>> Note, I phrased this controversial on purpose to generate a bit of list >>>>>> discussion: “abstracting away” something like usage of multiple paths >>>>>> should get some people to disagree?! Regarding the primitives we have so >>>>>> far, there doesn’t seem to be a compelling need for a TAPS system to >>>>>> expose them to an application I think. (again, such abstraction always >>>>>> comes with loss of some control - at one end of this, you want to be in >>>>>> control of which transport protocol is used, which we don’t want here). >>>>>> Decisions need to be made... >>>>>> >>>>>> >>>>>> Multi-streaming seems to me to be an easier case: I can’t see any reason >>>>>> why an application would need to be in control of this. Mapping >>>>>> communication channels between the same end hosts onto the same >>>>>> transport connection (whatever protocol provides it) should always be >>>>>> beneficial. >>>>> I'm not sure I understand how an app can/should know about any of this. >>>>> It strikes me as involving the app deep in "how" things are done in >>>>> other layers, rather than indicating a preference on behavior it sees >>>>> (it really shouldn't "see" any of this directly, IMO). >>>>> >>>>> I.e., this would be a good place to take a lesson from QoS - the key is >>>>> to indicate a preference to the net based on "application visible >>>>> behavior", not to try to map things so directly based on semantics. >>>> This sounds like a misunderstanding, maybe I didn’t make myself clear >>>> enough - because I think we agree: >>>> an application can / should not know about any of this, IMO. It should >>>> just see a communication channel. >>>> >>>> So mapping these channels onto a transport connection is what I thought a >>>> TAPS system underneath the application could do, and the application won’t >>>> need to be bothered. >>> I was speaking to the broader point of this thread and generalizing >>> your point about multi-streaming to the multiple path case as well. >>> >>> (I didn't know if you felt that both cases should be handled the same >>> way or whether you were using multi-streaming as an easier case to argue) >> I focused on multi-streaming now as an easier case to argue :-) >> >> Let’s focus on this one first and then get to multipath. Sorry for the mixup! > > The thing multi-streaming gives that I see could be useful for an application > is the ability to give different priorities to different streams/flows. You > could abstract that in different ways, but you need some scope for what > streams/flows you prioritize between that multi-streaming gives you.
I agree - but I haven’t yet stumbled over prioritization as a service to the application in one of the SCTP RFCs… probably it’s there somewhere. If it exists, wouldn’t the concept of prioritization within a definable group of flows be better to expose than multi-streaming as such? (e.g. this could just as well be mapped down to methods that couple the congestion control of multiple connections instead of real multi-streaming) Cheers, Michael _______________________________________________ Taps mailing list [email protected] https://www.ietf.org/mailman/listinfo/taps
