I have a server and want to build redundancy at network level and its running RHEL 4.5
My server has two NIC cards and one(Primary)ETH0 would be used for actual application and other(Backup)ETH1 for the data backup and they both are isolated.
I cannot insert one more NIC card into the system so there is no way i can use network bonding.
I want to develop a mechanism where in if the primary NIC fails it should automatically bring up the IP of the Primary NIC as virtual interface on ETH1 as ETH1:1 and when the Primay NIC card ETH0 is back it should fall back to ETH0.
There are multi-port (4) network cards available fairly cheap. Intel comes to mind as a good choice. The Intel cards come with the driver and admin programs to do the virtual IP and fail-over you're seeking.
Is the IP failover on Intel cards also available under Linux? The OP is using RHEL 4.5, and I have had significant stability problems in the past with Intel network card drivers under Linux. There used to be two separate development efforts of Intel network drivers for Linux with each their own problems and functionality.