Hello,

Ok here is another thought :

after some more measurements, and 2 box connected w/ a crosscable,
I had a really strange big loss of a thousand packets, that are not 
reported even in the internal counters  (systat inet.ip 1 :run).

sending 10 000 000 udp packets at 40 000 p/s rate :

I'm speaking about internal counters only :

sender reports 10 000 000 packets sent
received reports 9 993 728 (missing 6272)

and my udp server test code reports
6272 missing.

It doesn't happend all the time, just since i'm stress testing.

is it possible that the nic card drops packets before passing to the 
driver ? like too much interrupts etc.. ?(that would explain the 
"missing" number in internal counters) ?.

the nic card used on the server side is a realtek (rtk0).

Regards,
Eric.