[root@localhost tftpboot]# nano /etc/sysconfig/network-scripts/route-eth0
GATEWAY0=172.33.55.16
NETMASK0=255.255.0.0
ADDRESS0=10.5.0.0
GATEWAY1=172.33.55.16
NETMASK1=255.255.0.0
ADDRESS1=10.100.0.0
Save it with CTRL + O.
Exit with CTRL + X
You can do a test by rebooting the network service using the command below:
service network restart
If you see the routes like below, you are good to go.
[root@localhost tftpboot]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
172.33.55.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
10.100.0.0 172.33.55.16 255.255.0.0 UG 0 0 0 eth0
10.5.0.0 172.33.55.16 255.255.0.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
0.0.0.0 172.33.55.254 0.0.0.0 UG 0 0 0 eth0
[root@localhost tftpboot]#