Date: Fri, 11 Apr 2008 04:55:48 -0700 From: Jeremy Chadwick <koitsu@freebsd.org> To: Damian Weber <dweber@htw-saarland.de> Cc: freebsd-stable@freebsd.org, Jack Vogel <jfvogel@gmail.com> Subject: Re: RELENG_6_3 ping and DUP packets Message-ID: <20080411115548.GA9854@eos.sc1.parodius.com> In-Reply-To: <Pine.BSO.4.64.0804110934440.20160@isl-s-02.htw-saarland.de> References: <396418019.20080409104542@serebryakov.spb.ru> <5f67a8c40804100944k3984ab8fp95b5d4b22f92dd30@mail.gmail.com> <Pine.BSO.4.64.0804102140550.30252@isl-s-02.htw-saarland.de> <C73D9407-5492-43F4-9BE6-E05C98661107@mac.com> <Pine.BSO.4.64.0804110842280.21736@isl-s-02.htw-saarland.de> <20080411065256.GA95213@eos.sc1.parodius.com> <Pine.BSO.4.64.0804110934440.20160@isl-s-02.htw-saarland.de>
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On Fri, Apr 11, 2008 at 11:51:15AM +0200, Damian Weber wrote: > On Thu, 10 Apr 2008, Jeremy Chadwick wrote: > > Date: Thu, 10 Apr 2008 23:52:56 -0700 > > From: Jeremy Chadwick <koitsu@freebsd.org> > > To: Damian Weber <dweber@htw-saarland.de> > > Cc: freebsd-stable@freebsd.org > > Subject: Re: RELENG_6_3 ping and DUP packets > > > > On Fri, Apr 11, 2008 at 08:48:10AM +0200, Damian Weber wrote: > > > > From: Chuck Swiger <cswiger@mac.com> > > > > To: Damian Weber <dweber@htw-saarland.de> > > > > Cc: freebsd-stable@freebsd.org > > > > Subject: Re: RELENG_6_3 ping and DUP packets > > > > > > > > On Apr 10, 2008, at 1:58 PM, Damian Weber wrote: > > > > > But here is the problem, pinging the machine from remote gives > > > > > > > > > > A.B.C.X$ ping A.B.C.D > > > > > PING A.B.C.D (A.B.C.D): 56 data bytes > > > > > 64 bytes from A.B.C.D: icmp_seq=0 ttl=64 time=0.272 ms > > > > > 64 bytes from A.B.C.D: icmp_seq=0 ttl=255 time=0.391 ms (DUP!) > > > > > > > > Please run "tcpdump -e icmp" on this box and repeat your testing. It > > > > will be most interesting to know whether you're seeing the same MAC > > > > address.... > > > > > > good point, but it's the same > > > > > > A.B.C.X# tcpdump -e icmp > > > tcpdump: listening on rl0, link-type EN10MB > > > 08:41:51.136023 0:20:ed:5f:3:3b 0:19:99:33:7c:9 ip 98: A.B.C.X > A.B.C.D: icmp: echo request > > > 08:41:51.136171 0:19:99:33:7c:9 0:20:ed:5f:3:3b ip 98: A.B.C.D: icmp: echo reply > > > 08:41:51.136343 0:19:99:33:7c:9 0:20:ed:5f:3:3b ip 98: A.B.C.D: icmp: echo reply > > > 08:41:52.138366 0:20:ed:5f:3:3b 0:19:99:33:7c:9 ip 98: A.B.C.X > A.B.C.D: icmp: echo request > > > 08:41:52.138447 0:19:99:33:7c:9 0:20:ed:5f:3:3b ip 98: A.B.C.D: icmp: echo reply > > > 08:41:52.138692 0:19:99:33:7c:9 0:20:ed:5f:3:3b ip 98: A.B.C.D: icmp: echo reply > > > ^C > > > 169 packets received by filter > > > 0 packets dropped by kernel > > > > Possibly an interrupt is being called twice on the same packet? > > > > Shot in the dark, but try disabling MSI/MSI-X and see if the problem > > recurs. Put this in /boot/loader.conf: > > > > hw.pci.enable_msi="0" > > hw.pci.enable_msix="0" > > > > Reboot, and see if the problem continues. > > Bingo! > > No duplicates anymore. > > Is this considered as a permanent solution or just a "hack"? > In any case, I've summarized it on > http://www-crypto.htw-saarland.de/weber/misc/unix/freebsd-dup-packets/ > > including the output of the mptable command (MSI disabled/enabled). > > Thanks a lot, We use MSI/MSI-X on our servers here, with em(4), and there's no problem. This leads me to believe that some motherboards vendors implement things oddly or incorrectly, or possibly it's a BIOS bug. I'm not really sure. Anyway, CC'ing Jack Vogel (em(4) maintainer), who can very likely answer this and/or help further. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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