Date: Mon, 14 Oct 1996 10:45:20 -0600 (MDT) From: Nate Williams <nate@mt.sri.com> To: question@freebsd.org Cc: Luigi Rizzo <luigi@labinfo.iet.unipi.it>, isp@freebsd.org Subject: Modem latencies (was Re: ppp over vty possible ? ) Message-ID: <199610141645.KAA00802@rocky.mt.sri.com> In-Reply-To: <199610141531.IAA20691@root.com> References: <199610141429.PAA13506@labinfo.iet.unipi.it> <199610141531.IAA20691@root.com>
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David Greenman writes: > >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 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. FWIW, my connection to home is using 2-28.8K USR Sportster's. I'm using SLIP and running both ends at 115K and have compression enabled. PING trout.mt.sri.com (206.127.76.104): 56 data bytes 64 bytes from 206.127.76.104: icmp_seq=0 ttl=255 time=156.701 ms 64 bytes from 206.127.76.104: icmp_seq=1 ttl=255 time=150.206 ms 64 bytes from 206.127.76.104: icmp_seq=2 ttl=255 time=132.611 ms 64 bytes from 206.127.76.104: icmp_seq=3 ttl=255 time=124.156 ms 64 bytes from 206.127.76.104: icmp_seq=4 ttl=255 time=124.328 ms 64 bytes from 206.127.76.104: icmp_seq=5 ttl=255 time=123.549 ms 64 bytes from 206.127.76.104: icmp_seq=6 ttl=255 time=120.484 ms 64 bytes from 206.127.76.104: icmp_seq=7 ttl=255 time=120.429 ms 64 bytes from 206.127.76.104: icmp_seq=8 ttl=255 time=120.162 ms 64 bytes from 206.127.76.104: icmp_seq=9 ttl=255 time=120.413 ms 64 bytes from 206.127.76.104: icmp_seq=10 ttl=255 time=118.633 ms 64 bytes from 206.127.76.104: icmp_seq=11 ttl=255 time=118.503 ms 64 bytes from 206.127.76.104: icmp_seq=12 ttl=255 time=118.059 ms I usually average around ~120ms, although I have seen it drop to 115ms at times. If I turned off modem compression I think I could get it down to 110ms. Nate
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