Hello, thanks for communicating with the cisco community below a small explanation
Multicast is used to send the same data packets to multiple receivers.
By sending to multiple receivers, the packets are not duplicated for every receiver. Instead, they are sent in a single stream, where downstream routers perform packet multiplication over receiving links.
Routers process fewer packets because they receive only a single copy of the packet. This packet is then multiplied and sent on outgoing interfaces where there are receivers.
Because downstream routers perform packet multiplication and delivery to receivers, the sender or source of multicast traffic does not have to know the unicast addresses of the receiver.
Simulcast, simultaneous delivery for a group of receivers, may be used for several purposes including audio and video streaming, news and similar data delivery, and software upgrade deployment.
Unicast vs. Multicast
Unicast transmission sends multiple copies of data, one copy for each receiver. In other words, in unicast, the source sends a separate copy of packet to each host that needs the information. Multicast transmission sends a single copy of data to multiple receivers.
The upper part of the figure shows a host transmitting three copies of data, and a network forwarding each packet to three separate receivers. The host may only send to one receiver at a time, because it must create a different packet destination address for each receiver.
The lower part of figure shows a host transmitting one copy of data, and a network replicating the packet at the last possible hop for each receiver. Each packet exists only in a single copy on any given network. The host may send to multiple receivers simultaneously because it is sending only one packet.
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