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 18.104.22.168/4 via 10.239.0.1