Table 1-1An analogy between TV transmission and multicast transmission

 

Step

TV transmission

Multicast transmission

 

 

1

A TV station transmits a TV program

A multicast source sends multicast data to

 

 

through a television channel.

a multicast group.

 

 

 

 

 

 

 

 

 

 

2

A user tunes the TV set to the channel.

A receiver joins the multicast group.

 

 

 

 

 

 

 

 

The user starts to watch the TV program

The receiver starts to receive the multicast

 

 

3

transmitted by the TV station via the

data that the source sends to the multicast

 

 

 

channel.

group.

 

 

 

 

 

 

 

4

The user turns off the TV set.

The receiver leaves the multicast group.

 

 

 

 

 

 

 

 

 

 

 

z

z

A multicast source does not necessarily belong to a multicast group. Namely, a multicast source is not necessarily a multicast data receiver.

A multicast source can send data to multiple multicast groups at the same time, and multiple multicast sources can send data to the same multicast group at the same time.

Advantages and Applications of Multicast

Advantages of multicast

Advantages of multicast include:

z

z

z

Enhanced efficiency: Multicast decreases network traffic and reduces server load and CPU load.

Optimal performance: Multicast reduces redundant traffic.

Distributive application: Multicast makes multiple-point application possible.

Application of multicast

The multicast technology effectively addresses the issue of point-to-multipoint data transmission. By enabling high-efficiency point-to-multipoint data transmission, over an IP network, multicast greatly saves network bandwidth and reduces network load.

Multicast provides the following applications:

z

z z z

Applications of multimedia and flow media, such as Web TV, Web radio, and real-time video/audio conferencing.

Communication for training and cooperative operations, such as remote education. Database and financial applications (stock), and so on.

Any point-to-multiple-point data application.

Multicast Models

Based on the multicast source processing modes, there are three multicast models:

z

z

z

Any-Source Multicast (ASM)

Source-Filtered Multicast (SFM)

Source-Specific Multicast (SSM)

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