Assign IP Addresses to an Ethernet Interface

From privileged EXEC mode, access global configuration mode.
```
device# configure terminal
```
Access the interface to which you are assigning the IP addresses.
```
device(config)# interface ethernet 0/1
```

Assign one or more IP addresses, with a CIDR network mask.

device(config-if-eth-0/1)# ip address 11.1.1.11/24
device(config-if-eth-0/1)# ip address 11.11.1.11/24

To assign a secondary IP address, include the secondary keyword.
```
device(config-if-eth-0/1)# ip address 10.53.5.4/24 secondary
```
Note
You can configure a secondary IP address only if the primary IP address is already configured in the same subnet.
Activate the interface.
```
device(config-if-eth-0/1)# no shutdown
```

Verify that the IP addresses are assigned to the interface.

device(config-if-eth-0/1)# do show ip interface ethernet 3/14
 Ethernet 3/14 is up protocol is up
 Primary Internet Address is 11.1.1.11/24 broadcast is 11.1.1.255
 Primary Internet Address is 11.11.1.11/24 broadcast is 11.11.1.255
 Secondary Internet Address is 11.11.1.12/24 broadcast is 11.11.1.255
 IP MTU is 1500
 Proxy Arp is Enabled
 ICMP unreachables are always sent
 ICMP mask replies are never sent
 IP fast switching is enabled
 Vrf : default-vrf