What you're asking can be done a number of ways with different levels of complexity, the simplest using routing tables and IPTABLES. Instead of asking this list how to technically do this, I'd suggest that first you describe what you're trying to accomplish at a higher level. And be very specific. Then you will/should receive technical advice better suited to your problem.
I have a server with two NICs. One NIC is already configured for network A, but the second is disabled at the moment. I want to enable it too, but put it on network B. Unfortunately, I don't know how to do that. Well, what I've tried hasn't worked anyway.
Each NIC is plugged into a separate switch, and each network has it's own gateway. But, I can only set one default gateway. What parameters do I need to use in the NIC config file to force NIC 1 to use gateway 1, and NIC 2 to use gateway 2? I tried using "GATEWAY=blah" in each config file (ifcfg-eth0 and ifcfg-eth1), but it didn't work.
I'm over looking something.
Regards,
Ranbir