Enabling PIM on every interface
IOS:
G1R1(config)#ip multicast-routing
G1R1(config)#int eth0/0
G1R1(config-if)#ip pim sparse-mode
G1R1(config-if)#ip mroute-cache
..rinse. Repeat.
Pro1:
G1R1(config)#int range all
G1R1(config-if-range)#ip pim sparse-mode