A device, system and method for controlling the flow of multicast data packets from sources sending data to hosts requesting the data. In one implementation, a router is situated in a data network between sources that send multicast data packets directed to a multicast group and hosts requesting to receive the multicast data packets. The router has one or more network interfaces in the direction of the hosts and stores for each network interface, each multicast group address and each host at least one data record arising from one or more data requests made by the hosts which includes multicast group and source information. The router stores executable instructions to receive messages originating from a host, update the status of the data sources for that host and implement the actions according to one or a combination of Tables 3, 4, 5, 6 and 7 disclosed herein.