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MULTICAST OVERVIEW
Multicast Overview With development of networks on the Internet, more and more interaction
services such as data, voice, and video services are running on the networks. In
addition, highly bandwidth- and time-critical services, such as e-commerce, Web
conference, online auction, video on demand (VoD), and tele-education have
come into being. These services have higher requirements for information security,
legal use of paid services, and network bandwidth.
In the network, packets are sent in three modes: unicast, broadcast and multicast.
The following sections describe and compare data interaction processes in unicast,
broadcast, and multicast.
Information
Transmission in the
Unicast Mode
In unicast, the system establishes a separate data transmission channel for each
user requiring this information, and sends a separate copy of the information to
the user, as shown in
Figure 55:
Figure 55 Information transmission in the unicast mode
Assume that Hosts B, D and E need this information. The source server establishes
transmission channels for the devices of these users respectively. As the
transmitted traffic over the network is in direct proportion to the number of users
that receive this information, when a large number of users need this information,
Source
Server
Receiver
Receiver
Receiver
Host A
Host B
Host C
Host D
Host E
Packets for Host B
Packets for Host D
Packets for Host E
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