Ack! Full-Duplex and DEC DC21040 (rev 35)

tulip@duct.dhs.org tulip@duct.dhs.org
Thu Mar 18 21:30:37 1999


I have two machines with DEC DC21040 (rev 35)'s...  I just got a Kalpana
2015 switch and have been fooling with full-duplex.  My quick test has
been ftping from amchine to machine...  With full-duplex the transfer rate
goes down!  I have an Alpha and PII.  Both are running the same card
connected to the same switch.  I can get 800k/sec without FDX and anywhere
from 80->600k/sec with FDX enabled...  also the debug program says:

Index #1: Found a Digital DC21040 Tulip adapter at 0xec00.
 Port selection is 100mbps-SYM/PCS 100baseTx scrambler, half-duplex.
 Transmit started, Receive started, half-duplex.
  The Rx process state is 'Waiting for packets'.
  The Tx process state is 'Idle'.
  The transmit unit is set to store-and-forward.

Whats with the 100mbps? and yes I set the adapter back to half duplex...
that seems reported correctly.

here is my experimenation...
GD=Genaric Dec Driver
TP=Tulip Driver
FD=full duplex
HD=half duplex


Alpha			PII			Transfer Rate
TP,HD			GD,HD			800k/sec
TP,HD			TP,HD			800k/sec
TP,HD			GD,FD			80k/sec!!!
GD,FD			GD,FD			150K/sec
GD,FD			GD,HD			200k/sec
GD,FD			TP,FD			660k/sec


Ack!!!

I read somewhere abouit Kalpana and Dec chip incompatability...  Anyone
have word on this... 
				Keith