Cisco ENCOR Practice Exam 2025 – All-in-One Comprehensive Guide to Mastering Enterprise Network Core Technologies!

The function of RPF in multicast routing is Reverse Path Forwarding. This technique is crucial in ensuring that multicast packets are forwarded correctly across the network. RPF works by allowing a router to determine the best path to the source of the multicast traffic. When a router receives a multicast packet, it checks if the interface it received the packet on is the same interface that it would use to send a unicast packet back to the source. If it is, the multicast packet is forwarded out on the appropriate interfaces. This method helps to prevent loops and ensures that multicast packets are sent efficiently through the network.

By utilizing Reverse Path Forwarding, the multicast routing protocol can keep track of the source of the multicast traffic, thus ensuring that packets reach the intended receivers without unnecessary duplication or incorrect routing paths. This mechanism is fundamental in protocols like PIM (Protocol Independent Multicast), which rely on RPF as a method of decision-making for forwarding multicast packets.