[lwip-users] Re: [lwip] lwIP 0.5.3 tcp Checksum issues?

[Kieran Mansley]

On Mon, 22 Jul 2002, Michael Portmann wrote:
>   What's even more annoying is that I have compared the ROM pbuf
> checksum total with the win32 port's ROM pbuf checksum total - they are
> equal. I have calculated manually the TCP pbuf checksum and added this
> all up with the pseudo header and get the same checksum as that which
> was sent with the packet !! Surely the packet sniffing software and
> windows 2000 checksum implementation is correct ? ! I can assume that
> can't I ? ! :-)

It sounds like the correct checksum is being calculated when the packet is
transmitted, but this doesn't match the checksum calculated when the
packet is received at the other end.  This would suggest there is some
data corruption, and the checksum is doing what it's supposed to.  Can you
check your physical layer?  It seems a bit odd that this is happening so
much, but it seems like the first thing to check.

Kieran

[This message was sent through the lwip discussion list.]