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On Jul 29 2007 08:45, Willy Tarreau wrote: >On Sun, Jul 29, 2007 at 06:59:26AM +0100, Darryl L. Miles wrote: >> CLIENT = Linux 2.6.20.1-smp [Customer build]>> SERVER = Linux 2.6.9-55.ELsmp [Red Hat Enterprise Linux AS release 4 >> (Nahant Update 5)]>> >> The problems start around time index 09:21:39.860302 when the CLIENT issues >> a TCP packet with SACK option set (seemingly for a data segment which has >> already been seen) from that point on the connection hangs.>>Where was the capture taken ? on CLIENT or on SERVER (I suspect client from >the timers) ? A possible, but very unlikely reason would be an MTU limitation >somewhere, because the segment which never gets correctly ACKed is also the >largest one in this trace.[...] I had something similar (and most strangely enough, it only seemed to happen when the source and/or destination address was outside a given subnet). It boiled down to that some switch acted really strange and God knows why. A tcpdump on *both* sides (server+client) each showed that the *other* peer sent a FIN/RST. Well in the end I settled with setting sys.net.ipv4.tcp_sack=0, no idea if the broken switch got replaced in the meantime. Well, just letting you know that it is not limited to computers. Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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