The following diagram illustrates how filtering of IP directed broadcast traffic is enabled on the Router 3 interface. To enable filtering of IP directed broadcast traffic on Router 3 interface 1/2, configure a bACL permitting source IP address 10.1.1.2, and apply it that interface. Router 3 then allows IP broadcast packets from 10.1.1.2 and drops IP broadcast packets from other sources.
To configure a bACL on Router 3 interface 1/2, enter the following commands.
device# configure terminal device(config)# ip access-list standard bACL_int_3 device(conf-ipacl-std)# permit host 10.1.1.2 device(conf-ipacl-std)# exit device(config)# interface ethernet 1/1 device(conf-if-eth-1/1)# enable device(conf-if-eth-1/1)# ip address 10.1.1.1/24 device(conf-if-eth-1/1)# exit device(config)# interface ethernet 1/2 device(conf-if-eth-1/2)# enable device(conf-if-eth-1/2)# ip address 10.1.1.1/24 device(conf-if-eth-1/2)# ip subnet-broadcast-acl bACL_int_3 device(conf-if-eth-1/2)# exit