not needed due to Auto-RP, R4 will convert to sparse mode

R3#sh run int fa 0/1
Building configuration...

Current configuration : 142 bytes
!
interface FastEthernet0/1
 ip address 180.40.7.129 255.255.255.224
 ip pim dense-mode proxy-register list 102
 duplex auto
 speed auto
end

R3#sh access-list 102
Extended IP access list 102
    10 permit ip any any