Re: TCP checksum errors on mec0 on an O2

[Andy Ruhl <acruhl%gmail.com@localhost>]

On Fri, Nov 22, 2019 at 9:17 AM George Harvey <fr30%dial.pipex.com@localhost> wrote:
>
> Hi,
>
> I'm running NetBSD 8.1 on a R5000/180 O2 and seeing a lot of stalls and
> hangs when using FTP to send files over the mec0 Ethernet interface.
> Small files (less than around 4k) transfer successfully, anything much
> larger fails. On the receiving machine, the files are truncated at
> exactly 2896 bytes.
>
> Using WireShark on a separate machine, to sample the packets on the
> wire, I see that the first two packets are sent correctly and the third
> packet has a TCP checksum error. Data size in the packets is 1448
> bytes, which explains the 2896 bytes at the receiving end. I've had a
> look in if_mec.c and I can see the receive checksum routine,
> mec_rxcsum, but I don't see the transmit checksum. Is it done by the
> MACE chip or is it somewhere else in the code?

Possibly not much help but if you look at "ifconfig" output you might
see if checksum is being done in the card or not.

Andy