I have some major problems using a DECchip 21140 NIC in an AlphaStation
500/266 under 1.6P. (I've written about this earlier, too). I'm using
tlp driver, and here's what dmesg says about the card

tlp1 at pci0 dev 12 function 0: DECchip 21140 Ethernet, pass 1.2
tlp1: interrupting at kn20aa irq 4
tlp1: DEC DE500-XA, Ethernet address 00:00:f8:30:28:35
tlp1: 10baseT, 100baseTX, 100baseTX-FDX, 10baseT-FDX

(Should I use de? I haven't tried it.)

The problem is that the NIC doesn't play very nice with my switch,
which is a DLink DES 1008D: I can't make the 21140 run reliably
in 100base mode.

I've been instructed earlier that I should let the NIC and switch
negotiate automatically the communications method they'll use,
but there are two problems

 a) When I boot the alpha, and boot NetBSD, either the switch and
    the NIC decide to use 10baseT, or then the NIC independently
    just likes 10baseT.
 b) I don't know how to make the card select media automatically.
    That is: if I start playing with the media options, I can't
    reset the card to renegotiate with the switch.

So, currently in my ifconfig.tlp1 I force the NIC to use
100baseTX. This ~works. When I first boot up, and the NIC is
configured, I need to unplug and replug the cable so that the
NIC would see the carrier. After this it works nicely. However,
it seems that if there's no network traffic on the NIC, it does
something very strange which effectively stops all traffic
at the switch. I've got all in all four machines connected to
the switch, and at some point all traffic just mysteriously
stop: any of the machines can't talk to any other. Doing
"ifconfig tlp1 down" resurrects the traffic for other machines.

Currently, I'm running the NIC at 10baseT which seems to work
nicely all the time. This is however quite suboptimal...