Maybe I did not enabled all options as I have not seen
the ASSERT() message.
[..]
Today I discovered some more interesting points about the TCP checksum
problem: the content of the packet sometimes changes with each
retransmission. The first as lost of zeros at the end. The later one
less zeros and - unfortunately not in the capture I send you - I've seen
retransmissions without zeros and correct checksum. This is something I
don't understand at all:
a) If there is any memory problem, I would assume, that the packet
content gets worth every retransmission.
b) If there is any DMA problem (pbuf is send to EMAC using DMA on
LPC1768) I would assume some DMA errors but not all zero content.
Do you have any idea whats going on there?