Cisco IOS - ALCs and ICMP unreachables.

If you use ACL to block the traffic, IOS will reply with “ICMP destination unreachable” messages. To disable it you can use “no ip unreachables” command.

interface FastEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 ip access-group LAN_IN in
 no ip unreachables

Admin area