On Fri, Jan 15, 2010 at 11:12:43AM -0800, alan bryan wrote: > I just read a different thread about problems with checksums on vge (and nfe > in the replies). > > I'll just chime in here with some more information - I have a couple other > message threads going about some weird high packet volumes on my new FreeBSD > 8.0-Release NFS server. I thought it might be an issue with the igb driver > so I put in a new card using em instead and got the exact same behavior. I'm > currently sifting through a tcpdump in wireshark and there are all sorts of > messages in there about checksums being incorrect - both TCP and UDP. This > is for communications between this client machine (FreeBSD 7.0-Release) and > any of the 8.0 machines I have. The packets going to non-8.0 machines (at > least so far) appear to be fine. > > I'll defer to those who know more than I about the networking code, but is > there perhaps an issue in general with the checksuming and not specific to > one card or driver - is that even possible? That's now 4 different drivers > all with various checksum problem reports. > > I'm going to be working on this all day today (and likely over the weekend) > so if I can help by supplying information please let me know what you need. >
If you are seeing bad checksum reported by tcpdump/wireshark for TX frames on checksum capable controller, it's normal. bpf(4) just sees TX frames before inserting checksum computed by hardware so tcpdump/wireshark reports invalid checksum. You can safely ignore that. If you want to verify whether sending host generated correct checksum, you should capture the frame on receive side. If tcpdump/ wireshark reports bad checksummed frame on received frames it's real bad checksummed frame. _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
