Which function do reverse path forwarding mechanisms perform in a multicast deployment?

PIM prune messages are generated by PIM protocol to stop unwanted multicast traffic on a branch, a separate mechanism from the RPF lookup process.

When a router receives a multicast packet, RPF checks whether it arrived on the interface that the router's unicast routing table identifies as the best path back to the source. If the check fails, the packet is discarded, which eliminates loops and prevents the same packet from being forwarded multiple times on different interfaces.

Overlapping multicast group addresses are managed through address allocation and rendezvous point design, not by RPF mechanisms.

RPF is a local per-packet check; it does not send notifications to upstream routers - PIM join/prune messages serve that upstream signaling function.