Chuck Swiger wrote: > Denis Shaposhnikov wrote: > > tcpdump of one of failed requests: > > > > 10:35:03.592164 IP 192.168.0.100.1035 > 192.168.0.2.3128: S > > 1423332:1423332(0) win 8192 <mss 536,nop,nop,sackOK> > > 10:35:03.592274 IP 192.168.0.2.3128 > 192.168.0.100.1035: S > > 2428819522:2428819522(0) ack 1423333 win 0 <mss 536> > > It's interesting that it responds with a zero window size. That is > typically used by the network stack to indicate extreme congestion > and to have the other side wait for some seconds without sending any > more data. > > BTW, why are you using such a small MTU? 576 is Windows' default MTU/MRU for slow PPP (over serial) connections. I think it used to be even less for very slow links (296 bytes, IIRC). The purpose is to reduce the amount of data lost when a spike in the telephone line destroys a packet. That's especially important when using analogue equipment (modems) and old telephone lines. For example, if you have a bad telephone line with an average of one spike (or other kind of glitch) every 2 seconds, that amounts to 16% packet loss on a 38.4k connection with 1500 bytes MTU. With 576 bytes that's only 6% packet loss, and with 296 bytes it's only 3%. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "Being really good at C++ is like being really good at using rocks to sharpen sticks." -- Thant TessmanReceived on Fri Jan 12 2007 - 07:02:56 UTC
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