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Chapter 9
Multicast
F I G U R E 9 . 1
Unicast communication
The unicast process, then, is a two-way communication. These two hosts
are interested only in communicating with one another. So what happens
when one host wants to talk to multiple hosts or all of the hosts on the same
network segment? That is where broadcast communications come in.
Broadcast
Now that you have a good understanding of unicast, we can discuss the prin-
ciple of broadcast communication on networks. Whereas unicast messages
target a single host on a network (unicast communication can be compared
to sending an e-mail to a friend; the mail is addressed to the friend, and it is
sent from you),
broadcast
messages are meant to reach all hosts on a broad-
cast domain. Figure 9.2 depicts a broadcast message sent from HostX to all
machines within the same broadcast domain.
F I G U R E 9 . 2
Broadcast message on a network
Server
172.16.1.0/24
HostC
HostB
HostA
HostX
Server
172.16.1.0/24
HostC
HostB
HostA
HostX
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