3Com 3C905B performance on 100TXFD

[Daniel =?iso-8859-1?Q?Kr=F6ning?=]

Hello,

I have three machines:

A: Pentium 166, Linux 2.0.35, 3Com 3C905 (not B), Driver v0.99E
B: Pentium II 333, Linux 2.0.35, 3Com 3C905B, Driver v0.99H
C: Pentium II 350, Linux 2.0.35, 3Com 3C905B, Driver v0.99H

All connected with a D-Link 8 Port 100 mbit/s switch via twisted pair.

Machine A runs very stable at 100 mbit/s full-duplex, as expected, with
great performance. The problem are machines B and C. With v0.99E,
machines B and C negotiated 10 mbit/s half-duplex with the switch as
soon as the interface went up with ifconfig. Forcing it to 100 mbit/s FD
in the driver, the performance was too bad because of excessive
collisons, since the switch did not recognize the FD-setting.

This was fixed with v.099H. Both the cards and the switch now
automatically negotiate 100mbit/s full duplex. Unfortunately, the
performance of the machines with the 3C905B cards is very poor, about
200kb/s on ftp. In fact, it was faster with 10mbit/s half duplex, always
above 900kb/s.

Neither the switch nor the cards reports collisions. Replacing a 3C905B
with the 3C905 (not B) fixes the performance problem. However, I am
unable to find a vendor for more 3C905 cards.

Thank you for your help,

Daniel Kröning