When a router receives a multicast packet, RPF will check the routing table and check which interface it would use if it were to send traffic back to the multicast sender. If the interface matches the interface that the multicast packet was just received on, then the packet is accepted, otherwise it is dropped.
1.6c i Sparse Mode Instead of flooding multicast traffic to all potential receivers, PIM Sparse Mode builds explicit multicast distribution trees from the receivers to the sources. To build an explicit tree to the source, receivers and sources should have a way to dynamically discover each other – Rendezvous Points. The biggest challenge facing PIM… read more »
1.6.a i IGMPv2, IGMPv3 IGMP (Internet Group Management Protocol) is used to dynamically register individual hosts in a multicast group on a particular LAN. Hosts identify group membership by sending IGMP packets to their local multicast router. Under IGMP, routers listen to IGMP packets and periodically send queries to discover which groups are active/inactive on… read more »