Using the 2 P5WDH NICS simultaneously?

[limini]

I've got 2 gigabit NICS on my P5WDH: one hooked up to a network via a gigabit switch, and the other connected to a local second computer also equipped with a gigabit NIC using a Cat 6 crossover cable. Under XP, I have both P5WDH NICs bridged and I don't have any issues seeing any computer on the network and their shares from any other. The network uses fixed IP addresses.

 

But when running OSX (Jas 10.4.8), as long as the local computer connected directly to the P5WDH is off, I have no issues with connectivity to the internet or with any other shares on the network. However if I have this local computer on when booting into OSX, OSX sees this computer but fails to see anything else. Every item in the OSX Network panel has its own unique IP address but switching between them does nothing: I just can't see the network.

 

If I shutdown the second computer the network stays unavailable, but if I reverse the two network cables around the network is back: this is what I'm calling the "OSX 2-NIC ping-pong effect". Interestingly shutting down the P5WDH doesn't reset the cable switching as OSX seems to remember which was the last "valid" NIC.

 

So the question is really this: is it possible on a P5WDH under OSX to use and access 2 NICs and network branches at the same time? Or is there something I'm missing?

 

Thanks for any pointers!