Date: Fri, 31 Oct 2003 02:44:31 -0500 (EST) From: Daniel Eischen <eischen@vigrid.com> To: Lars Eggert <larse@ISI.EDU> Cc: current@freebsd.org Subject: Re: wi problem with message > 7400 bytes Message-ID: <Pine.GSO.4.10.10310310224150.9071-100000@pcnet5.pcnet.com> In-Reply-To: <3FA1EF1A.7070000@isi.edu>
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On Thu, 30 Oct 2003, Lars Eggert wrote: > Daniel Eischen wrote: > >> > >>Could you post a tcpdump for each case? I wonder if this is related to a > >>fragmentation issue I've seen in the past. > > > > 22:46:43.513038 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52198:1480@0+) > > 22:46:48.522475 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52199:1480@0+) > > 22:46:53.532018 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52200:1480@0+) > > 22:46:58.541178 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52201:1480@0+) > > 22:47:03.553048 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52202:1480@0+) > > 22:47:08.568862 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52203:1480@0+) > > 22:47:13.583328 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52204:1480@0+) > > 22:47:18.578512 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52205:1480@0+) > > 22:47:23.609098 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52206:1480@0+) > > 22:47:28.597680 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52207:1480@0+) > > 22:47:33.607059 gpz.foo.bar.com.38340 > vespa.12345: udp 7393 (frag 52208:1480@0+) > > It's not what I've seen in the past - but also pretty strange! Only the > first fragment seems to be received. Wonder what happened to the other > fragments... > > If you tcpdump on gpz, does the output look the same? Also, you may want I'll try that tomorrow. gpz is a Sun Solaris 9 box at work, but before you say "try another BSD box", I already did. I tried 2 other FreeBSD boxes in place of gpz and I had the same results. > to run the tcpdump without a filter (if you don't do this already) to > see if the other fragments show up as corrputed frames or something. > > (As an aside, fragmentation on a lossy link compounds throughput issues, > but of course you know that already.) Everything is behind Cisco 10/100 switches and doing 10/100 full duplex except for the laptop (vespa) which is through a Dell TrueMobile wireless access point. The access point is connected to a switch and is about 10 feet away from the laptop. I tried this test at home with a different setup: orion - laptop with D-Link DWL-650H PC-Card (wi) sirius - FreeBSD current box with em interface Linksys WRT-54g router/access point with builtin 10/100 switch There is no other traffic on this network; orion and sirius are standalone. sirius is wired to a 10/100 port in the router/access point and is at 100 full-duplex. Repeating the same test lets me send messages up to 25152 bytes in length, much better than 7400. This seems to be about the same limit I hit in VxWorks (which supposedly has the BSD 4.4 IP stack). I'll see if I can get my hands on a different access point at work to see if that makes a difference. Here's the tcpdump from the above setup with message size 25153: 05:27:59.632708 sirius.49245 > orion-home.12345: udp 25153 (frag 19970:1480@0+) 05:27:59.815829 sirius > orion-home: udp (frag 19970:1480@1480+) 05:28:00.023248 sirius > orion-home: udp (frag 19970:1480@2960+) 05:28:00.216317 sirius > orion-home: udp (frag 19970:1480@4440+) 05:28:00.404066 sirius > orion-home: udp (frag 19970:1480@5920+) 05:28:00.583116 sirius > orion-home: udp (frag 19970:1480@7400+) 05:28:00.777315 sirius > orion-home: udp (frag 19970:1480@8880+) 05:28:00.950056 sirius > orion-home: udp (frag 19970:1480@10360+) 05:28:01.129616 sirius > orion-home: udp (frag 19970:1480@11840+) 05:28:01.327645 sirius > orion-home: udp (frag 19970:1480@13320+) 05:28:01.560564 sirius > orion-home: udp (frag 19970:1480@14800+) 05:28:01.769612 sirius > orion-home: udp (frag 19970:1480@16280+) 05:28:01.945923 sirius > orion-home: udp (frag 19970:1480@17760+) 05:28:02.128897 sirius > orion-home: udp (frag 19970:1480@19240+) 05:28:02.309202 sirius > orion-home: udp (frag 19970:1480@20720+) 05:28:02.514941 sirius > orion-home: udp (frag 19970:1480@22200+) 05:28:02.731612 sirius > orion-home: udp (frag 19970:1480@23680+) 05:28:02.907988 sirius > orion-home: udp (frag 19970:1@25160) 05:28:07.982121 sirius.49245 > orion-home.12345: udp 25153 (frag 20226:1480@0+) 05:28:08.150171 sirius > orion-home: udp (frag 20226:1480@1480+) 05:28:08.357960 sirius > orion-home: udp (frag 20226:1480@2960+) 05:28:08.551270 sirius > orion-home: udp (frag 20226:1480@4440+) 05:28:08.754906 sirius > orion-home: udp (frag 20226:1480@5920+) 05:28:08.953891 sirius > orion-home: udp (frag 20226:1480@7400+) 05:28:09.145286 sirius > orion-home: udp (frag 20226:1480@8880+) 05:28:09.365111 sirius > orion-home: udp (frag 20226:1480@10360+) 05:28:09.577964 sirius > orion-home: udp (frag 20226:1480@11840+) 05:28:09.795675 sirius > orion-home: udp (frag 20226:1480@13320+) 05:28:09.973760 sirius > orion-home: udp (frag 20226:1480@14800+) 05:28:10.167432 sirius > orion-home: udp (frag 20226:1480@16280+) 05:28:10.362543 sirius > orion-home: udp (frag 20226:1480@17760+) 05:28:10.559922 sirius > orion-home: udp (frag 20226:1480@19240+) 05:28:10.775048 sirius > orion-home: udp (frag 20226:1480@20720+) 05:28:10.937800 sirius > orion-home: udp (frag 20226:1480@22200+) 05:28:11.115078 sirius > orion-home: udp (frag 20226:1480@23680+) 05:28:11.300522 sirius > orion-home: udp (frag 20226:1@25160) -- Dan Eischen
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