Operation Manual – MulticastH3C S5600 Series Ethernet Switches Chapter 1 Multicast Overview1-4SourceServerReceiverReceiverReceiverHost AHost BHost CHost DHost EPackets for the multicast groupFigure 1-3 Information transmission in the multicast modeAssume that Hosts B, D and E need the information. To transmit the information to theright users, it is necessary to group Hosts B, D and E into a receiver set. The routers onthe network duplicate and distribute the information based on the distribution of thereceivers in this set. Finally, the information is correctly delivered to Hosts B, D, and E.The advantages of multicast over unicast are as follows:z No matter how many receivers exist, there is only one copy of the same multicastdata flow on each link.z With the multicast mode used to transmit information, an increase of the number ofusers does not add to the network burden remarkably.The advantages of multicast over broadcast are as follows:z A multicast data flow can be sent only to the receiver that requires the data.z Multicast brings no waste of network resources and makes proper use ofbandwidth.1.1.4 Roles in MulticastThe following roles are involved in multicast transmission:z An information sender is referred to as a multicast source (“Source” in Figure 1-3).z Each receiver is a multicast group member (“Receiver” in Figure 1-3).z All receivers interested in the same information form a multicast group. Multicastgroups are not subject to geographic restrictions.
