> Peter Broadbery <pab@obscurity.demon.co.uk> writes:
> >
> > I've noticed that I'm getting a lot of TCP bad checksums when
> > connecting to the net via PPP. These started when I upgraded to
> > 2.1.108 from 2.1.99.
>
> TCP checksum errors occur naturally under VJ compression when an
> earlier frame is dropped because it fails the PPP CRC check. The most
> likely cause is dropping of received characters because of missed
> interrupts. Disabling VJ compression will make the symptom disappear
> but will not fix the underlying problem.
>
> In particular, somewhere in the 2.1.92 to 2.1.106 transition, most
> SCSI drivers were modified to be more SMP-friendly. The result was
> that some drivers, in particular "fdomain.c", now disable interrupts
> for extended periods of time. It's possible that "fdomain" has been
> fixed---I submitted a patch to Linus about this---but I haven't
> checked. However, there are probably other SCSI drivers with the same
> problem.
>
> Can I ask, are you using SCSI disks and, if so, does the number of
> checksum errors noticeably increase when the disks are active?
Sorry to ruin your theory, but I am also seeing the PPP checksum
problems and I do not use SCSI anything nor VJ compression. In fact,
ifconfig shows these errors on my eth0 (3COM 3C509 NIC) and loopback
devices also. I have pppd 2.3.5 and the latest iptools, which I upgraded
to in an attempt to fix this problem. Didn't help.
Jon
--- 'Cloning and the reprogramming of DNA is the first serious step in becoming one with God.' - Scientist G. Richard Seed
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