This command is used to set IP addresses on an interface.
R1(config)#ip address <IP address> <subnet mask> <secondary>
|<IP address>||IP address for the interface|
|<subnet mask>||IP address for the interface|
|<secondary>||Sets the IP address as a secondary IP address, you can have many secondary IP addresses on an interface if required. Though some routing protocols do not function properly with secondary addresses.|
In this example, we set the ip address of int fa0/0 on R2.
Next, to test it out, we do a quick ping to the new ip address.
R2(config-if)#ip add 188.8.131.52 255.255.255.240 secondary
R2(config-if)#do ping 184.108.40.206
Type escape sequence to abort.