Problem with full duplex with DEC 21143-PC CNET CN100TX(E)

Brian Dushaw
Thu Nov 5 23:20:16 1998

I have not been able to get my CNET CN100TX(E) fast ethernet
cards to operate at 100baseTx full duplex.  I presently have
four of these cards in two computers connected via null modem
cables.  I can rule out problems with the cables, and problems
with individual cards.  The driver I am using is tulip.c:v0.90
and "options=5,5" does not work.

half duplex is verified by ftp simultaneous in both directions,
as well as by netperf simultaneous in both directions.  Half
duplex works just fine.

I conclude that either this particular card/chip has a design flaw
or the present driver cannot enable full duplex.

To summarize:
This is a CNET CN100TX(E) card which has a
DEC 21143-PC chip on it with the date Dec 96

The documentation for the card specifically sez that full
duplex 100baseTx is supported, however.

It does not have MII.

I do not know if full duplex works under windows

They certainly are quirky cards - they appear to take considerable
time to "warm up"....
The card cost $15 each however. delivered
3 cards of my latest order of 4, and these cards are no longer listed 
on the jandr site.  It appears as if I got the last of 'em (for now)

However, thanks very much for the free driver software!