Re: [lwip-users] need urgent help in debugging retransmission issue

[Sergio R. Caprile]

If you are using the very same driver, it could still have been buggy
and happen to pass unnoticed until something triggered it.
The fact that the data gets lost when you call lpc_low_level_output()
means that it gets lost after it left lwIP. The only way I can see lwIP
running again (and destroying your data) between that call and the
Ethernet output is your driver returning control or your port (that
includes the RTOS) interrupting the driver when it should not.
Well, there is the possibility that "someone" writes when it shouldn't,
but that looks like a port bug again.

If your driver is DMA-based, then the picture is more complicated, and
if you have caches a bit more. In both cases, anyway, afaik, your port
and driver have the highest probability of being guilty.