Each interface has its own context in the CLI, which you use to manage the interface. The set of commands related to an interface are only accessible from its interface context. For example, in order to configure the Loopback interface, you must first enter the Loopback context. You enter the Loopback context using the interface command with an interface identifier such as interface loopback 1.

When an interface has only one sub-interface, the commands for the sub-interface are available from the context of the parent interface. This is called unified configuration. When there are multiple sub-interfaces, you must enter the context of a particular sub-interface in order to configure the sub-interface.

For example, when you create a new VLAN interface 1, the sub-interface VLAN 1.0 is also created. In this case, you can execute sub-interface context commands such as ip admin-state from the parent context. If you add a second sub-interface VLAN 1.1, then you can only execute sub-interface commands from the context of the sub-interface.

If you are in Supervisor or Privileged mode, you can enter any of the following interface contexts:

• Interface USB-modem

• Interface Dialer

• Interface FastEthernet

• Interface VLAN

• Interface Loopback

• Interface Tunnel