Chapter 1 Multicast Overview; Information Transmission In The Unicast Mode - H3C S7500 Series Operation Manual

Operation Manual – Multicast
H3C S7500 Series Ethernet Switches

Chapter 1 Multicast Overview

1.1 Multicast Overview
With development of networks on the Internet, more and more interaction services
such as data, voice, and video services are running on the networks. In addition,
services highly dependent on bandwidth and real-time data interaction, such as
e-commerce, web conference, online auction, 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 in unicast,
broadcast, and multicast.

1.1.1 Information Transmission in the Unicast Mode

In unicast, the system establishes a separate data transmission channel for each user
requiring this information, and sends separate copy information to the user, as shown in
Figure 1-1:
Source
Server
Figure 1-1 Information transmission in the unicast mode
Assume that users B, D and E need this information. The source server establishes
transmission channels for the devices of these users respectively. As the transmitted
traffic over the network is proportional to the number of users that receive this
Packets for Host B
Packets for Host D
Packets for Host E
Host A
Receiver
Receiver
Receiver
Host E
1-1
Chapter 1 Multicast Overview
Host B
Host C
Host D