[En-Nut-Discussion] changes in nicrtl driver

[Harald Kipp]

Hi Stephen,

thanks, that was very helpful. I should have spent more time reading
your previous postings. Somehow I've been on the wrong track. I wasn't
aware, that the Realtek doesn't support link negotiation at all.

I can confirm your's and Damian's observation. Full duplex seems to
be possible only with our manageable switch, which allows to force
ports to full duplex.

However, still I do not fully understand, why collisions appear.
The original Ethernet coaxial cable obviously did not support full
duplex. Twisted pair with separate transmit and receive lines
offers this option. But even if the switch is in half duplex
mode, there should be no collisions when Ethernut starts transmitting
a packet while the switch is transmitting another. Of course the
switch's hardware is able to detect this, but it doesn't make
sense to me.

Harald