Enabling PIM SM Snooping
Use PIM SM snooping only in topologies where multiple PIM sparse routers connect through a device. PIM SM snooping does not work on a PIM dense mode router which does not send join messages and traffic to PIM dense ports is stopped. A PIM SM snooping-enabled device displays a warning if it receives PIM dense join or prune messages.
The PIM SM traffic snooping feature assumes that the network has routers that are running PIM SM.