Operation Manual – MulticastH3C S7500 Series Ethernet Switches Chapter 1 Multicast Overview1-5Multicast provides the following applications:z Applications of multimedia and flow media, such as Web TV, Web radio, andreal-time video/audio conferencing.z Communication for training and cooperative operations, such as remoteeducation.z Database and financial applications (stock), and so on.z Any point-to-multiple-point data application.1.2 Multicast ArchitectureIP multicast is designed to transmit information from a multicast source to receivers inthe multicast mode and to satisfy information requirements of receivers. You should beconcerned about:z Host registration: What receivers reside on the network?z Multicast source discovery: Which multicast source should the receivers receiveinformation from?z Multicast addressing mechanism: Where should the multicast source transmitinformation to?z Multicast routing: How is information transmitted?IP multicast is a kind of peer-to-peer service. Based on the protocol layer sequencefrom bottom to top, the multicast mechanism contains addressing mechanism, hostregistration, multicast routing, and multicast application.z Addressing mechanism: Information is sent from a multicast source to a group ofreceivers through multicast addresses.z Host registration: A receiving host joins and leaves a multicast group dynamicallyto implement multicast membership registration.z Multicast routing: A router or switch establishes a packet distribution tree andtransmits packets from a multicast source to receivers.z Multicast application: A multicast source must support multicast applications, suchas video conferencing. The TCP/IP protocol stack must support the function ofsending and receiving multicast information.1.2.1 Multicast AddressAs receivers are multiple hosts in a multicast group, you should be concerned about thefollowing questions:z What destination should the information source send the information to in themulticast mode?z How to select the destination address, that is, how does the information sourceknow who the user is?These questions are about multicast addressing. To enable the communicationbetween the information source and members of a multicast group (a group of
