Re: TCPv4 bad checksum in 2.1.131-ac8/9/10

Paul Flinders (paul@dawa.demon.co.uk)
16 Dec 1998 08:26:14 +0000


Jamie Lokier writes:
> On Tue, Dec 15, 1998 at 08:18:56AM +0000, Paul Flinders wrote:
> > Is anyone else seeing bad checksums in recent kernels?
>
> Yes. The recent slews really are bad packets coming in.
> I.e., someone (me) did some checksums by hand on raw packets to check.

I now think it _is_ probably hardware, although I've got ISDN I use an
external TA so an RS232 connection is involved (and RS232 is almost
inherantly unreliable :-( )

>
> (Unless there's something really subtle going on in the kernel,
> corrupting the raw packet data but passing the PPP CRC).

I did think of checking that - I'm not seeing ppp checksum errors but...

>
> > I don't seem to have lost any data so I'm wondering if it's a hardware
> > problem but I've only noticed it in the last 2 days (since I installed
> > ac 8 or 9)
>
> Do you get it consistently enough to check if using an older kernel
> makes it go away?

Yes I get it very consistently and using an older kernel does make it
"go away" but only because 2.0.36 doesn't bother reporting them!

If I patch the kernel to include a bad checksum error message I see
them in 2.0.36 as well

I'll do a bit more digging but I think that it's probably hardware -
time to buy an ISDN card methinks (although where I'll find an IRQ for
it...)

-- 
Paul

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