Re: Re: HighSpeed TCP for Large Congestion Windows
Sally Floyd <floyd <at> icir.org>
2002-08-01 18:05:31 GMT
>My read was somewhat different. While some were interested in exploring
>this (IMO, 'academically'), most felt that because it wasn't of
>near-term utility it was premature for the WG.
>My own thoughts, as mentioned at the IETF, are that there are
>interesting aspects to this, but I'm uncomfortable with proposing three
>modifications at once. That either means there's a more fundamental
>problem, or that some of the solutions are marginal, or both.
I think that there are two completely separate fundamental problems.
One is that the current TCP response function requires unrealistically
low packet drop rates to sustain congestion windows of thousands
or tens of thousands of packets. The second fundamental problem
is that if best-effort connections want to *start* with large
windows, then they need explicit permission from all of the
routers along the path (in my view).
I think these are separate problems, with completely separate time
scales, as I thought I made clear in my presentation. That is, it
would make sense to me for the HighSpeed TCP draft to be mulled
over and then, in the fullness of time, if it is judged by the
community not to be unduly dangerous and/or unfair, to become an
Experimental RFC, so that more real-world experience can be gathered.
The Limited Slow-Start draft is a small, completely optional proposal
that, in my view, is useful to allow TCP connections to effectively
slow-start up to those very large congestion windows. It is a
separate draft from the HighSpeed draft, however, because it could
be useful with or without the modified response function of HighSpeed
TCP. Just a small piece that, in a reasonably simple and low-overhead