Multicast PIM Assert and dense mode
PIM assert is a multicast feature that is used to eliminate duplicate multicast traffic coming from two or more multicast routers connected to a single network segment. PIM Assert is only useful in a multicast environment where dense mode is being used.
The PIM forwarder should not be confused with the PIM designated router (DR). The PIM forwarder forwards the actual multicast traffic while the DR is responsible for forwarding the PIM join messages.