As for me, congestion exists if long TCP sessions can't adapt their window sizes and packet drop if more than 3 - 5 % over connection line. This means more than 1,000 - 2,000 tcp sessions through 2 Mbit link, for example. Yes, IP is connectionless protocol, but Internet is not connectioonless network in real life...

Craig Nordin <cnordin@vni.net> wrote:

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Er. There's no such thing as perfect transport as long as TCP is concerned. If end-hosts support large windows, even a single TCP session will load the network to the point where it'll lose packets.

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What you say here makes sense to me. But, out of a 500 ping sample over the course of half a day, I was getting well below one percent loss -- six months ago.

Most TCP sessins are pretty short, in fact. They simply have no chance to open window. Also, there's a lot of old TCP implementations which have window limited to 64Kb (or less!).

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Now, my same sample group is going for more than three percent, with many ten percent loss routes showing...

Well, nobody argues that Internet is overloaded. But the question of how to measure the congestion is not as simple as just pinging.

The problem is that there's no reasonable way to learn loss statistics from routers.

--vadim

--- Aleksei Roudnev, Network Operations Center, Relcom, Moscow (+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 239-10-10, N 13729 (pager) (+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)