Static routes will be added usually through "route add" command. The drawback of 'route' command is that, when Linux reboots it will forget static routes. But to make it persistent across reboots, you have to add it to /etc/sysconfig/network-scripts/route-<eth> .
To add static route using "route add":
# route add -net 192.168.100.0 netmask 255.255.255.0 gw 192.168.10.1 dev eth0
Adding Persistent static route:
You need to edit /etc/sysconfig/network-scripts/route-eth0 file to define static routes for eth0 interface.
Save and close the file. Restart networking:
# service network restart
Verify new routing table:
# route –n
# netstat –nr