Date: Tue, 3 Aug 1999 16:31:57 -0400 From: Justin Wells <jread@semiotek.com> To: freebsd-net@freebsd.org Subject: how to configure FreeBSD for unreliable network Message-ID: <19990803163157.C17569@semiotek.com>
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I have a FreeBSD 3.2 box sitting on a network that has a reasonably fast connection to the outside world. Linux boxes on this network get 30-40k/sec, but my FreeBSD box gets less than 1k/sec on the same link. The link has fairly good bandwidth (2-3 Mbit) but horrible reliability (sometimes up to 20-30% packet loss). Basically it's an ADSL link operating a little too far away from the CO, so the cable length is longer than the spec says it should be--the consequence being a fast, but not very reliable link. Nevertheless, FreeBSD gets 1k/sec whereas Linux gets 30-40k/sec. (Actually, only recent Linux kernels perform well, older ones suffer the same way that FreeBSD does, making me think it's a tcp stack issue.) It seems that what's happening is that there's a long retry in FreeBSD, and a nearly instantaneous one in Linux. So while FreeBSD stops and waits for nearly a full second before retrying, Linux recovers and resumes. This is just my theory and may be full of BS. I don't really totally know what's going on--I do know that I can start a huge number of these 1k/sec transfers without slowing any of them down any further, so the bandwidth is obviously there. At any rate--what can I do to configure my FreeBSD boxes to work well across this lousy link? It's embarassing that Linux is showing better network performance ;-) Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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