R3#sh run | b ip pim bi
ip pim bidir-enable
ip pim spt-threshold 1
ip pim rp-candidate FastEthernet0/1 group-list 1 interval 10 bidir


R2#sh run | b ip pim bi
ip pim bidir-enable
ip pim spt-threshold 1
ip pim bsr-candidate FastEthernet0/1 0

on all other routers


ip pim bidir-enable