In IGMPv2, what happens if a router does not receive Report messages?

In IGMPv2 (Internet Group Management Protocol version 2), if a router does not receive IGMP Report messages from hosts that are indicating their desire to join a multicast group, the router interprets this lack of response as an indication that there are no active members for that multicast group on the local network segment. Consequently, the router will delete the membership for that multicast group.

This mechanism is crucial for efficiently managing multicast traffic. By allowing the router to remove multicast group memberships when no hosts are actively participating, it helps in conserving network resources and reducing unnecessary multicast traffic on the network.

The process is time-sensitive; if the router does not receive Reports within a specific timeframe, it takes the action of deleting the membership associated with that multicast group. This ensures that the network only forwards multicast data to segments that have registered members, optimizing overall performance.