Enables fowarding of directed broadcasts. When this is turned on for an interface, the interface will respond to broadcast messages that are sent to its subnet.
In this example, IP directed-broadcasts is enabled on in fa0/0 on R2. A broadcast is sent and the response from both interfaces is received. Next, we issue an IP directed-broadcast to the subnet of fa0/0. Since ip directed-broadcast is enabled on this inteface, it responds.
R2#conf t Enter configuration commands, one per line. End with CNTL/Z. R2(config)#int fa0/0 R2(config-if)#ip directed-broadcast
R2(config-if)#do ping 255.255.255.255 repeat 1Type escape sequence to abort. Sending 1, 100-byte ICMP Echos to 255.255.255.255, timeout is 2 seconds: Reply to request 0 from 10.1.1.1, 28 ms Reply to request 0 from 10.2.2.3, 28 ms
R2(config-if)#do ping 10.1.1.255 repeat 1Type escape sequence to abort. Sending 1, 100-byte ICMP Echos to 10.1.1.255, timeout is 2 seconds: Reply to request 0 from 10.1.1.1, 24 ms