Static mroutes are similar to static unicast routes in that they override any dynamic route entries. The difference is that static mroutes are not used for any forwarding. Instead, they are used to statically configure the RPF interface for a source, overriding the information in the unicast routing table. The command ip mroute is used along with an IP address and mask to specify an address or range of addresses. An RPF interface or RPF neighbor address is also specified, just as a static unicast route specifies either an outgoing interface or a next-hop neighbor.
R1(config)# ip multicast-routing distributed
R1(config)# ip mroute 10.1.1.88 255.255.255.255 Tunnel0
R1(config)# exit