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1 Multicast Overview
In this manual, the term “router” refers to a router in the generic sense or a Layer 3 Ethernet switch
running an IP multicast protocol.
Multicast Overview
With the development of the Internet, more and more interaction services such as data, voice, and
video services are running on the network. In addition, highly bandwidth- and time-critical services,
such as e-commerce, Web conferencing, online auctions, 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 for unicast, broadcast, and multicast traffic.
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 1-1:
Figure 1-1 Information transmission in the unicast mode
