At Thu, 10 Jul 2008 11:43:23 +0100 (BST), rwatson wrote: > > On Wed, 9 Jul 2008, [EMAIL PROTECTED] wrote: > > > I would assume that if a card, say the em, has hardware TX checksum that > > the > > UDP checksum could be calculated by the hardware, but this seems not to be > > the case. The manual pages are unhelpful in this regard. > > On the whole, they should be generated in hardware as long as it's > not administratively disabled with ifconfig, and as long as there > aren't know bugs in the hardware for the rev you're using. Just for > example, hardware checksumming is disabled in software for quite a > few early 1gbps cards due to bugs in the hardware causing rather > nasty side effects. What specific problem are you seeing? We do do > a software checksum of the pseudo-header, but the UDP data should be > checksummed by hardware. > > (The usual test for hardware checksum being enabled on transmit is > to tcpdump the interface and see tcpdump reporting lots of bad > checksums, as the BPF capture happens before hardware checksumming > is run -- in principle on the receive side that shouldn't happen!) >
If the sysctl it turned off on the transmitter then the receiving machine sees UDP checksums of 0. Best, George _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
