Multicasting in computer network is a group communication, where a sender(s) send data to multiple receivers simultaneously. It supports one – to – many and many – to – many data transmission across LANs or WANs. Through the process of multicasting, the communication and processing overhead of sending the same data packet or data frame in minimized.
Ethernet multicast constitutes multicasting at the data link layer of the OSI model for Ethernet networks. Ethernet frames for multicasting are identified by a 1 bit in the LSB (least significant bit) of the first byte of the destination address.
IP multicast provides one-to-many communication over an IP network. The destination nodes send join and leave messages that informs the routers whether they are correct recipients of the messages. The sender sends the data packet only once irrespective of the number of users. The routers in the network performs necessary replications so that the packet can reach multiple receivers simultaneously.