You report on the status of an interface using the show interfaces command. The command reports on the administrative status of the interface, its operational status, and its extended operational status (the ICMP keepalive status). For information about ICMP keepalive status, refer to ICMP keepalive.

For example, if an interface is enabled but normal keepalive packets are failing, show interfaces displays:

FastEthernet 10/3 is up, line protocol is down

However, if normal keepalive reports that the connection is up but ICMP keepalive fails, the following is displayed:

FastEthernet 10/3 is up, line protocol is down (no KeepAlive)