Enables the ICMP keepalive mechanism on an interface. ICMP keepalive is a mechanism that reports on the status of an IP address and its next hop. The destination interface is only declared to be alive if the next hop is also reachable. This feature is critical for mechanisms such as policy-based routing that must guarantee service on a particular path. Use no keepalive-icmp to disable extended keepalive on the interface.
Note:
You cannot configure both keepalive-icmp and ip address dhcp (DHCP Client) on the WAN FastEthernet interface.