3Com Switch 8800 Advanced Software V5 Configuration Guide

37
MULTICAST OVERVIEW
n
■ The term "router" in this document refers to a router in a generic sense or a
Switch 8800 running the multicast routing protocol.
■ Unless otherwise stated, the term "multicast" in this document refers to IP
multicast.
Introduction to
Multicast
As a technique coexisting with unicast and broadcast, the multicast technique
effectively addresses the issue of point-to-multipoint data transmission. By
allowing high-efficiency point-to-multipoint data transmission over a network,
multicast greatly saves network bandwidth and reduces network load.
With the 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 videoconferencing, and other information
services that have high demands on the bandwidth and real-time data
communication.
Comparison of
Information
Transmission Techniques
Unicast
In unicast, the information source sends a separate copy of information to each
host that needs the information, as shown in
Figure 155.
Figure 155 Unicast transmission
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