21143 specific problems

Donald Becker becker@cesdis1.gsfc.nasa.gov
Tue Sep 28 15:35:21 1999

On Tue, 28 Sep 1999, David Sean Friedman wrote:

> I've been having some problems with the tulip driver on 21143-based
> cards. The problem is that the cards seem unable to sustain more than 1
> Mb/s on a 100 Mb link when transmitting tcp traffic.

What driver version?

Only v0.91 and later does autonegotiation correctly when using a 21143 with
a SYM mode transceiver that requires specific output value on the
general-purpose pins.

(Yes, that's a very specific set of conditions.  Two years ago MII
transceivers were the common connection type, and the older driver works
correctly with them.  The changes in the newer 21143 chips and the lower
cost of SYM mode transceivers has made 21143+SYM designs popular.)

> However, if I use a 21140-based SMC NIC, the TCP transmit traffic is ~60Mb/s.

My guess is that the link partner is seeing the autonegotiation complete,
but then isn't getting the 100Mbps link beat quickly enough.  It then drops
to speed-sensing mode and ends up with a 100baseTx half duplex link.
Getting the updated driver should fix this problem.

Donald Becker					  becker@cesdis.gsfc.nasa.gov
USRA-CESDIS, Center of Excellence in Space Data and Information Sciences.
Code 930.5, Goddard Space Flight Center,  Greenbelt, MD.  20771
301-286-0882	     http://cesdis.gsfc.nasa.gov/people/becker/whoiam.html