Consider a video stream that needs to be sent to multiple recipients in a company. One approach is to unicast the traffic. The source server sends a copy of every packet to every receiver. Obviously, this approach has serious scalability limitations.
An alternative approach is to broadcast the video stream so that the source server has to send each packet only one time. However, everyone in the network receives the packet in that scenario, even if they do not want it.
IP multicast technologies provide the best of both worlds. With IP multicast, the source server sends only one copy of each packet, and packets are sent only to intended recipients.
Specifically, receivers join a multicast group, denoted by ...