General problems with checksums (txcsum/rxcsum) on FreeBSD 8.0?

alan bryan alan.bryan at
Fri Jan 15 19:12:46 UTC 2010

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.


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