R1# sh run | b interface Ethernet0/0
interface Ethernet0/0
 ip address 17.57.100.1 255.255.255.0
 ip pim sparse-dense-mode
 ip igmp access-group 1
 half-duplex
!

!
access-list 1 deny   224.20.73.1 15.128.20.0
access-list 1 permit any