If you want IP routes that persist across network restarts and system reboots do the following. Create a file in /etc/sysconfig/network-scripts called route-ethX. Where X is whatever the number of the specific ethernet device you want to store routes for. Here is a sample of my route-eth1 file.

10.100.41.0/24 via 10.239.0.1
224.0.0.0/4 via 10.239.0.1