Date: Mon, 11 Jan 2010 15:38:33 -0800 From: David Ehrmann <ehrmann@gmail.com> To: pyunyh@gmail.com Cc: freebsd-current@freebsd.org Subject: Re: vge traffic problem Message-ID: <4B4BB679.2060500@gmail.com> In-Reply-To: <20100111203557.GB1228@michelle.cdnetworks.com> References: <4B40AFFA.6090706@gmail.com> <20100103221630.GV1166@michelle.cdnetworks.com> <4B47B4F6.8030106@gmail.com> <20100109013145.GG18529@michelle.cdnetworks.com> <4B4ACD68.5030907@gmail.com> <20100111203557.GB1228@michelle.cdnetworks.com>
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Pyun YongHyeon wrote: > If receiver drops TX UDP frame sent by vge(4) would you try > disabling TX checksum offloading of vge(4)? If packet drop happens > only with UDP frames it could be checksum offload bug. Does your > controller is VT6130(PCIe)? > First, netstat before and after the test: share2# netstat -I vge0 -d Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll Drop vge0 1500 <Link#1> 00:40:63:xx:xx:xx 38940717 0 0 55913584 0 0 0 vge0 1500 10.0.0.0/22 share2 38886994 - - 55898223 - - - share2# netstat -I vge0 -d Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll Drop vge0 1500 <Link#1> 00:40:63:xx:xx:xx 38942065 0 0 55914869 0 0 0 vge0 1500 10.0.0.0/22 share2 38888320 - - 55899491 - - - The error counters were uninteresting. Here's what the internal counters said, but they weren't very interesting, either: http://pastebin.com/m20114095 I ran the test, again, and had tcpdump capture the packets (on the host with the vge interface). tcpdump -i vge0 -w dump.cap -K -s 0 host 10.0.1.2 When I opened it up in Wireshark, it's reporting that the outgoing UDP checksums are incorrect; they're always 0x1ae3. That said, maybe the checksums are done in hardware AFTER tcpdump sees them. I set net.inet.udp.checksum to 0. The bad checksums are gone, but I still see dropped packets. It's on the motherboard, probably wired directly to a PCI-E connection, but yes, it is a VT6130.
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