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Re: [RRG] Are we solving the wrong problem?



Mark,

right, but i think that what is missing in all these proposals [like HIP, SHIM6, etc] is to understand the interaction with congestion control, which may be critical if they get deployed.

Absolutely. The stable load-balancing properties come out of using multiple links simultaneously in such a way that congestion on one path causes more bytes to be sent the other way. But crucially it must not move all the traffic the other way, or the system is unstable and can oscillate backwards and forwards between the multiple paths.

So far I fully agree, even don't I cannot claim really understanding the issue. [Kelly & Voice is very next on my reading list; Bob B. commended it too, in addition to Marcelo.]

This is the reason why I think you can solve the problem at L4 without changing the apps (or at the application layer, but only if you change the apps), but I don't think you get the same properties if you solve the problem below layer 4.

Here I do not agree, due to a) signalling efficiency, b) mobility, c) path sharing within the network, and I guess a couple of other things I just don't remember this early moment.

I still think that we should reconsider the sublayering or location of functionality within layers 3/4, and rethink where to put congestion control. For congestion control, we should apparently separate flow-related functions (at transport) and path-related functions (at end-to-end), where path-related functions are shared by all flows going over the same path. [Consider also John Day's view in his new book, where he basically claims that logically layers 3 and 4 form just one single layer, and some of the layering we've done is just architecturally wrong due to us not understanding this.]

--Pekka


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