Re: Ping flooding

[Vern Paxson <vern () ee lbl gov>]

> Really, consider a link where the path carrying most of the data has
> a time of N and the path carrying the ack has a path 2N or N + 1/2N
> You are computing an average which seems like it could be skewed based
> on the path the ack takes.

This doesn't matter.  The key notions for TCP are (1) what's the time scale
for feedback, and (2) what's the pipe size (= bandwidth-delay product).
Both of these are determined by the RTT and not the one-way prop time.

> Does anyone know of any papers on the effect of asymetric paths on TCP
> performance?

Well, I thought about this quite a bit for my end-to-end routing study
(ftp://ftp.ee.lbl.gov/papers/routing.SIGCOMM.ps.Z).  I really wanted to
come up with some reason why asymmetric routing has serious implications
for TCP performance, but wasn't able to.  I guess this is a good thing,
since 50% of the paths in my study were asymmetric in terms of visiting
at least one different city in the two directions.  30% visited at least
one different AS.

                Vern
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