Date: Mon, 14 Oct 1996 16:30:15 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: dg@root.com Cc: exidor@nimbus.superior.net, question@FreeBSD.org, isp@FreeBSD.org Subject: Re: ppp over vty possible ? Message-ID: <199610141530.QAA13670@labinfo.iet.unipi.it> In-Reply-To: <199610141531.IAA20691@root.com> from "David Greenman" at Oct 14, 96 08:31:00 am
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> >large block to attempt compression. But -- apart for this being a > >symptom of poor design in the modem -- what is intriguing me is > >the delay -- 200ms -- so close to what is a TCP_FASTTIMEOUT. > > fastimeout can't be involved with pings since they use ICMP, not TCP. 14.4K I was not using ping, I have a modified kernel which prints out the current RTT and bandwidth for every connection (I am doing some experiments on congestion control stuff right now). The same could be seen with tcpdump, I guess, just a bit more annoying to do time differences. BTW the same kernel showed that using "telnet", a large number of telnet options (31 bytes if I remember well) is exchanged at every newline. Not that one should care much (at least, with a symmetrical channel), but it is impressive how many things occur behind (or below) you. > modems usually have large delays due to buffering and compression delays. Some > are better than others. I used to see 170ms on certain Intel modes, and as low > as 110ms on certain 28.8K Hayes modems. Supra's are usually about the worst > at near 200ms. Thanks for these data points. How did you get them, using ping or something else ? Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================
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