Problems with Tulip DS21143 on Kernel 2.2.3

[Roberto Mameli]

Hi all,

I have found a problem with linux tulip drivers.
My situation is the following. I have three Linux boxes (Kernel 2.2.3):
A, B and C

A ----- B ----- C

They are interconnected by means of 4 Tulip cards. Two of them are
Digital DS21143, while the others have Digital DS21140 chipset. On all
Linux boxes Tulip cards are installed as modules and the driver version
is 0.90q (the latest available). I have forced them to work in
100baseTx-FD mode by putting options=5 in the /etc/conf.modules file The
strange phenomenon is the following: if a TCP flow is exchanged between
two back-to-back cards the throughput depends on the types of cards
involved. More precisely:

    - from DS21140 to DS21140 the throughput reaches 95 Mb/s;
    - from DS21143 to DS21143 the throughput falls down to 800 Kb/s;
    - from DS21140 to DS21143 the throughput is again 800 Kb/s as
before;
    - from DS21143 to DS21140 the throughput has an intermediate value
of 26-27 Mb/s;

The same doesn't happen with UDP flows, since in all cases the
throughput is up to 95 Mb/s. I have tried to exchange cards between PCs
so as to test all possible configurations. I think it is a problem in
the driver. If you have any advice you can answer me in the mail box.

Thanks in advance
Roberto