ne2000 / Checksum errors

Erik M Pennebaker (
Mon, 7 Apr 1997 10:30:38 -0500 (CDT)

I appologize if this has been covered; I've been a little spotty
keeping up with the list.

I have 2 linux boxes connected via coax to an ISDN router. The
ISDN routers has been annoying me for longer than the problem I'm
about to describe; it seems to hit 40 - 50 % packet loss for brief
perdiods of time, and my boxes don't recover well. This happened
on my original setup with 2 3c509 cards ( 1 on each machine ).
Both machines had some timeout problems with the 3c509s.
The 3c509s were borrowed, and I had to give one back to the owner. I
replaced it with a PCI ne2000 clone from Best Buy, thinking I just
needed something cheap...

I can only get it to detect on the 2.1.x I need to give
more info to the 2.0.x kernels? I've been doing some big renderings,
and the 2.1 kernels are getting frustrated...

More intersting question:

After the PCI ne2000 was installed, I noticed this (2.1.29/30 kernels):

Apr 7 10:08:16 jericho kernel: TCPv4 bad checksum from c726ae80:0050 to da1311c0:3a0e, len=1480/1480/1500
Apr 7 10:08:17 jericho kernel: TCPv4 bad checksum from a30829c0:0050 to da1311c0:38c1, len=249/249/269
Apr 7 10:08:17 jericho kernel: TCPv4 bad checksum from a30829c0:0050 to da1311c0:38f5, len=247/247/267

[ etc ]

These come often and in big spurts. The hex ip addresses always corelate
to a session that is having problems...

My question, than is:

1) Do the 2.0 kernels not log TCP checksum errors, and I've been getting
errors before the PCI ne2000/2.1 kernels, and not noticing? I've
gotten 20 ICMP checksum errors in total on the 2.0.28/ISA card machine
since Jan. 22; nothing like above.


2) Is this a 2.1 kernel prob?


3) Is my card shitty/broken/dumb?

I'm really hoping number 1 is the case, since that would imply that
the ISDN line has a problem corrupting packets.

Again, sorry if some of this has been covered. I'd really appreciate
your help! It gets frustrating looking at 4 windows, all frozen...


Erik Pennebaker  |  |
              If bushes were trees, trees would be fallin'.
CCSO Workstation Support Group, University of Illinois         My opinions