I am in the situation where I have a number of CentOS Linux servers which all have two NIC interfaces. Currently one of these interfaces is used for internal communication, the other is used for external (internet) communication. Both of the NIC's are connected to the same switch.
My intention is to move both of these tasks to the first NIC and assigning it both an internal and external IP. Doing this will free the second NIC from all of its tasks, which then will be available for being connected to a second (back-up) switch.
The second NIC should the also receive an internal and a external IP address. My question is this: What should I do regarding the IP addressing on the second NIC? When the first switch or NIC breaks is there a way to automatically assign the IP info of NIC1 to NIC2? Or could I always give the the same IP information and let the switches work out the best route? What are proven techniques to accomplish this?