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Multicast overview
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.
By using multicast technology, a network operator can 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.
The term "router " in this document refers to both routers and Layer 3 switches.
Unless otherwise stated, the term "multicast" in this document refers to IP multicast.
Information transmission techniques
The information transmission techniques include unicast, broadcast, and multicast.
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
, 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.
Source
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
IP network
