Date: Thu, 2 Aug 2012 10:23:50 -0700 From: YongHyeon PYUN <pyunyh@gmail.com> To: John <jwd@freebsd.org> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: 0 frame length? Message-ID: <20120802172350.GA3097@michelle.cdnetworks.com> In-Reply-To: <20120801221240.GA24976@FreeBSD.org> References: <20120801221240.GA24976@FreeBSD.org>
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On Wed, Aug 01, 2012 at 10:12:40PM +0000, John wrote: > Hi Folks, > > On a Dell R610 system, I've been tracking down some nework issues > and ran across this in a tcpdump: > > 0000 84 2b 2b fd be 2e f0 4d a2 08 c4 13 08 00 45 00 .++....M ......E. > 0010 00 00 f0 2a 40 00 40 06 00 00 0a 18 09 ee 0a 18 ...*@.@. ........ > 0020 1e 08 58 57 14 02 5e 30 ea dc 61 84 62 b3 80 18 ..XW..^0 ..a.b... > 0030 08 00 42 10 00 00 01 01 08 0a 1e 67 b2 58 dc 56 ..B..... ...g.X.V > 0040 81 12 4e 45 54 50 41 43 4b 04 00 00 00 00 00 00 ..NETPAC K....... > .... additional packet data > > offset 0x10 should be the frame length - not 0. This only seems to happen > in packets being sent from this system/interface. > > Corresponding interface: > > bce0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500 > options=c01bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE> > ether f0:4d:a2:08:c4:13 > inet 10.24.9.238 netmask 0xffff0000 broadcast 10.24.255.255 > media: Ethernet autoselect (1000baseT <full-duplex,flowcontrol,rxpause,txpause>) > status: active > > > 8.2-RELEASE > > Wireshark reports: > > Bogus IP len (0, less than header length 20) > > > In googling, I've seen comments about lro/tso & the *csum options. > I have those set to off for the next time the systems get rebooted. > The firmware is also slightly out-of-date and I'll probably update > that also after finding out what the updates target. > > > Does anyone have any ideas what the problem might be, or place > I might want to look? I have a 9.1 system being put in to run some > comparison benchmarks against to see if the same problem occurs. > Try disabling TSO and see whether that makes any difference. (You don't need to reboot the box) I recall there were several reports that frames generated via TSO had bad IP length. And the issue seems to happen on several ethernet drivers. Unfortunately I was not able to reproduce that.
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