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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.