Operation Manual – MulticastH3C S7500 Series Ethernet Switches Chapter 1 Multicast Overview1-4z Multiple receivers receiving the same information form a multicast group. Multicastgroup is not limited by physical area.z Each receiver receiving multicast information is a multicast group member.z A router providing multicast routing is a multicast router. The multicast router canbe a member of one or multiple multicast groups, and it can also managemembers of the multicast groups.For a better understanding of the multicast concepts, you can assimilate a multicastgroup to a TV channel. A TV station is a multicast source. It sends data to the channel.The audience are the receivers. After turning on a TV set (a computer), they can selecta channel to receive a program (namely join in a group) and then watch the program.Therefore, a multicast group should be an agreement between the sender and thereceivers, like the frequency of a channel.Caution:A multicast source does not necessarily belong to a multicast group. A multicast sourcesends data to a multicast group, and it is not necessarily a receiver. Multiple multicastsources can send packets to the same multicast group at the same time.There may be routers that do not support multicast on the network. A multicast routerencapsulates multicast packets in unicast IP packets in the tunnel mode, and thensends them to the neighboring multicast routers through the routers that do no supportmulticast. The neighboring multicast routers remove the header of the unicast IPpackets, and then continue to multicast the packets, thus avoiding changing thenetwork structure greatly.1.1.4 Advantages and Applications of MulticastI. Advantages of multicastAdvantages of multicast include:z Enhanced efficiency: Multicast decreases network traffic and reduces server loadand CPU load.z Optimal performance: Multicast reduces redundant traffic.z Distributive application: Multicast makes multiple-point application possible.II. Application of multicastThe multicast technology effectively addresses the issue of point-to-multipoint datatransmission. By enabling high-efficiency point-to-multipoint data transmission, over anIP network, multicast greatly saves network bandwidth and reduces network load.
