network collisions, only with FreeBSD

[Ondrej Suchy]

Hi,

I recently ran across interesting problem, never seen anything like this.

I have 4.8-RELEASE with two ethernet NIC, one is 3Com 3c905-TX using xl 
driver, second is onboard Intel Pro/100 using fxp.

The network is *very* slow via xl0 interface. scp'ing file over 100mbit 
network from a host just one hop away, I get around 10 kbps (!). 
Changing mediaopt from autoselect (=> full-duplex) to half-duplex I get
slightly better results, but still very poor. Over fxp0 it is much 
better, but still not perfect.

dmesg:

netstat -in:
Name Mtu  Network       Ipkts Ierrs    Opkts Oerrs  Coll
xl0* 1500 <Link#1>       3253   626     2547     0   496
xl0* 1500 fe80:1::260       0     -        0     -     -
xl0* 1500 192.168.3         0     -        0     -     -
fxp0 1500 <Link#2>      37696   461    26505     0 26544
fxp0 1500 fe80:2::207       0     -        0     -     -
fxp0 1500 192.168.3     37694     -    26499     -     -

As you see, there is many input errors and many collisions. However, 
other computers with various operating systems behave normally when
plugged into the same cable.

I have tried multiple cards, all 3Com behave the same way. 
Interestingly, the server didn't detect Realtek card, this
makes me thing there might be some hw problems or IRQ
collisions (how do I find that?)

I don't know what else should I try, does anyone have any idea?

Thanks and have a nice day
   Ondrej