Re: PPP --- TCP bad checksums

Kevin Buhr (buhr@stat.wisc.edu)
12 Aug 1998 02:53:51 -0500


"Jon M. Taylor" <taylorj@ecs.csus.edu> writes:
>
> 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.

There's not only one way to lose interrupts. I was losing them on my
IDE interface when I upgraded to a fast disk on my slow 486/33
machine. I had slews of checksum errors until I finally figured out
why it was happening, tried "hdparm -u1" to enable interrupts during
IDE transfers, and watched my checksum errors disappear.

The only reason I suggested the SCSI interface as the culprit is
because it underwent exactly the right kind of modification around the
time Peter was talking about.

Of course, it's possible that *other* parts of the kernel underwent
changes that increased interrupt latency.

Kevin <buhr@stat.wisc.edu>

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