Directed Broadcast

A directed broadcast address for each physical network has all ones in the host ID part of the address. The packet originates from a network device that is not part of the destination subnet and is forwarded in the same manner as a unicast packet sent to its destination subnet. When the packet reaches the directed broadcast address, if directed broadcast is enabled on the device, it is sent to every host on the destination network or subnetwork by rewriting the directed broadcast address to that of the standard broadcast address on that destination subnet. If directed broadcast is disabled on the destination interface, directed broadcasts are dropped.

Use the ip directed-broadcast command, in interface configuration command mode, to enable directed broadcasts for directed broadcasts sent to this interface.