H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 311)

28-5
Table 28-1 An analogy between TV transmission and multicast transmission
Step TV transmission Multicast transmission
1
A TV station transmits a TV program through
a channel. A multicast source sends multicast data to a
multicast group.
2 A user tunes the TV set to the channel. A receiver joins the multicast group.
3
The user starts to watch the TV program
transmitted by the TV station via the channel.
The receiver starts to receive the multicast
data that the source sends to the multicast
group.
4
The user turns off the TV set or tunes to
another channel. The receiver leaves the multicast group or
joins another group.
z
A multicast source does not necessarily belong to a multicast group. Namely, a multicast source is
not necessarily a multicast data receiver.
z
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 the multicast technique include:
z
Enhanced efficiency: reduces the CPU load of information source servers and network devices.
z
Optimal performance: reduces redundant traffic.
z
Distributive application: Enables point-to-multiple-point applications at the price of the minimum
network resources.
Applications of multicast
Applications of the multicast technique include:
z
Multimedia and streaming applications, such as Web TV, Web radio, and real-time video/audio
conferencing.
z
Communication for training and cooperative operations, such as distance learning and
telemedicine.
z
Data warehouse and financial applications (stock quotes).
z
Any other point-to-multiple-point data distribution application.
Multicast Models
Based on how the receivers treat the multicast sources, there are two multicast models:
ASM model
In the ASM model, any sender can send information to a multicast group as a multicast source, and
numbers of receivers can join a multicast group identified by a group address and obtain multicast