Problem with full duplex or MII with DEC 21143

[Brian Dushaw]

I have a pair of DEC 21143 cards connected via a null modem
cable.  These work fine at 100baseTX, except that I can't
get full duplex to enable.  I can set options=14, in which
case full duplex is reported by tulip-diag, but then the
cards will not communicate.  I have tried a variety of options,
(including no options) and a variety of driver versions (0.88 0.89L 0.90
etc) all to no avail.  Any ideas?

A related problem may be that MII appears not to be recognized.
dmesg reports:

tulip.c:v0.89L 10/9/98 becker@cesdis.gsfc.nasa.gov
eth1: Digital DS21143 Tulip at 0xc000, 00 80 ad 22 13 53, IRQ 10.
eth1:  EEPROM default media type Autosense.
eth1:  Index #0 - Media 10baseT (#0) described by a 21142 Serial PHY (2)
block.
eth1:  Index #1 - Media 10baseT-FD (#4) described by a 21142 Serial PHY
(2) block.
eth1:  Index #2 - Media 100baseTx (#3) described by a 21143 SYM PHY (4)
block.
eth1:  Index #3 - Media 100baseTx-FD (#5) described by a 21143 SYM PHY (4)
block.

and that's all.  On the mailing list archive someone showed another line
concerning MII, that I do not appear to have.

These were $15 cards, so perhaps I am paying for this now....
The card is CNET CN100TX, it advertises full duplex capability.

Thanks,
Brian Dushaw