Chapter 23 Ip Multicast Overview; Ip Multicast Overview; Problems With Unicast/Broadcast - 3Com 8800 Configuration Manual

3Com Switch 8800 Configuration Guide

Chapter 23 IP Multicast Overview

Note:
An Ethernet switch functions as a router when it runs IP multicast protocol. A router that
is referred to in the following represents a generalized router or a layer 3 Ethernet
switch running IP multicast protocol.

23.1 IP Multicast Overview

23.1.1 Problems with Unicast/Broadcast

The constant development of the Internet and increasing interaction of versatile data,
voice and vedio information over the network, has promoted the emergence of new
services like e-commerce, network conference, online auction, vedio on demand (VoD),
and tele-education. These services require higher information security and greater
rewards.
I. Data transmission in unicast mode
In unicast mode, every user that needs the inforamtion receives a copy through the
channels the system separately establishes for them. See Figure 23-1.
Unicast
Server
Figure 23-1 Data transmission in unicast mode
Suppose that Users B, D, and E need the information, the information source Server
establishes transmision channels with every of them. Since the traffic in transmission
increases with the number of users, excessive copies of the information would spread
Chapter 23 IP Multicast Overview
User A
User B
User C
User D
User E
23-1