Well don't know if this is complex or not, but here goes
I have a number of Linux servers sitting behind a PIX in a datacenter. They're all on a private address range. THis is all working fine. The pix connects to the ISP's router. All well and good.
However, as the datacentre is 4 hours drive away, I'm paranoid that should the PIX fail, i'm in trouble.
What I want to do to mitigate any outages, is to connect the second NIC on each server to the ISP's switch.
Question: Can I set the second NIC to a public IP address given by the ISP and route traffic to the application on the server and still maintain the private subnet on the first?
In otherwords, if the PIX fails, is it possible to still have connectivity with the server and can they co-exist? Can I isolate routing, so that traffic on eth0 goes via the pix and eth1 (ip tables) routes via the direct connection?