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Multicast overview
NOTE:
This document focuses on the IP multicast technology and device operations. Unless otherwise
stated, the term
multicast
in this document refers to IP multicast.
Introduction to multicast
As a technique that coexists with unicast and broadcast, the multicast technique effectively
addresses the issue of point-to-multipoint data transmission. By enabling high-efficiency
point-to-multipoint data transmission over a network, multicast greatly saves network bandwidth and
reduces network load.
The multicast technology enables a network operator to easily provide new value-added services,
such as live webcasting, web TV, distance learning, telemedicine, web radio, real-time video
conferencing, and other bandwidth-critical and time-critical information services.
Information transmission techniques
Unicast
In unicast transmission, the information source must send a separate copy of information to each
host that needs the information.
Figure 1 Unicast transmission
In
, assume that Host B, Host D and Host E need the information. A separate transmission
channel must be established from the information source to each of these hosts.
In unicast transmission, the traffic transmitted over the network is proportional to the number of hosts
that need the information. If a large number of hosts need the information, the information source