> It would be interesting to know what the collision rate was like.

Nil.  I ran netstat -i 5 on the -current machine and got on the order of
300 packets in 5 seconds with 6-10 collisions, then nothing for the next
interval, then another 300 / 6-10, then nothing, etc...

I should mention that I ran tcpdump on the -current machine (the
one running ftpd), not the 1.3.1 machine (running the ftp client).  I
don't know if running ping would have had the same effect.  I can try to
reproduce the behavior.  Both systems do hard-code the media type to
100baseTX, but I have seen the odd behavior with the media auto-detection.
I'm seeing the de0 driver change the Tx threshold a couple times:

de0: abnormal interrupt: transmit underflow (raising TX threshold to 8|512)
de0: abnormal interrupt: transmit underflow (raising TX threshold to 1024)

Does this help?

-allen

-- 
                    Allen Briggs - briggs@ninthwonder.com