Basic Multicast Framework

This section describes the basic multicast framework and key multicast techniques that transmit multicast data from a source to multiple receivers. Table 1 shows the key multicast techniques.

**Table 1** Key multicast techniques
Multicast Technique	Description
Host registration	Determines whether a receiver exists.
Multicast source discovery technology	Determines the multicast source.
Multicast addressing mechanism	Determines the multicast data destination.
Multicast routing	Forwards multicast data.

IP multicast is an end-to-end service. Figure 1 shows the four IP multicast functions from the lower protocol layer to the upper protocol layer.

Figure 1 IP multicast basic framework

The four functions operate as follows:

Addressing mechanism: transmits data to multicast groups based on multicast destination addresses.
Host registration: allows a host to dynamically join or leave a group, implementing group member management.
Multicast routing: sets up a distribution tree to transmit packets from a source to receivers.
Multicast application: To work together, multicast sources and receivers must support the same multicast application software, such as a video conferencing application. The TCP/IP protocol suite must support multicast data transmission and receipt.