Date: Tue, 12 Jun 2007 13:13:20 -0400 From: Bill Moran <wmoran@collaborativefusion.com> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: Weird "ignoring syn" problem Message-ID: <20070612131320.c120cd00.wmoran@collaborativefusion.com> In-Reply-To: <466EBE3E.3050105@freebsd.org> References: <20070612101949.646dcaa5.wmoran@collaborativefusion.com> <466EBE3E.3050105@freebsd.org>
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In response to Andre Oppermann <andre@freebsd.org>: > > Before we go into more detail: > > a) the em(4) driver is most likely totally unrelated to this Are you saying it's more likely to be a tcp stack problem? As an experiment, I tried to reproduce it over the loopback and was unable to, which points back toward the em driver ... > b) you may run out of socket on the client side and reuse them > too fast. Try to lower net.inet.ip.portrange.first to 30,000 > or so. I find that unlikely. The problem usually occurs reliably after less than 200 connections, and frequently after less than 50. > c) related to (b) you may have a lot of connections in TIME_WAIT > on the server catching not really stray packets. Try it with > net.inet.tcp.nolocaltimewait=1 That's the default. Also, I see no change in the behaviour of TIME_WAIT states (based on the output of netstat -f inet) no matter what I change that value to. And, just to finish out the debugging steps, the problem occurs with nolocaltimewait set to both 0 and 1. > d) if the above didn't help then it'd be very helpful to test > against a server with FreeBSD-current (the future 7.0) on > it. In -current we've got detailed logging of LISTEN socket > failures that allow rapid analysis of the problem. This will take some time. Also, I'm not seeing the problem on other, similar hardware. I'm considering swapping out that NIC to see if it might be buggy HW. -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/ wmoran@collaborativefusion.com Phone: 412-422-3463x4023
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