North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: NAP/ISP Saturation WAS: Re: Exchanges that matter...
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 <[email protected]> wrote: > > >> 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. > > >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!). > > >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) - - - - - - - - - - - - - - - - -
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