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ust as blue, green, and red are the primary colors, unicast,

multicast, and broadcast are the primary forms of communication on net-
works.

Today's Web and enterprise applications are directed to larger audiences

on the network than ever before, causing increased bandwidth requirements.
This increased demand on bandwidth can be accommodated with as little
cost increase as possible by using multicast. For example, voice and video are
being sourced for larger and larger audiences. One-on-one communications
can overwhelm both servers and network resources. Unlike unicast and
broadcast, however, multicast services can eliminate this problem.

This chapter will help you understand the differences in unicast, broad-

cast, and multicast communication methods and when each should be used.
Unicast is an excellent method of point-to-point communication, whereas
broadcast traffic is imperative for many systems and protocols to work on a
network. Multicast comes in as a bridge between these two communication
extremes by efficiently allowing point-to-multipoint data forwarding. It is
imperative that you understand how multicast addressing spans both layer 3
and layer 2 of the OSI model. You will also learn about the protocols and
tools used to implement and control multicast traffic on your network. As
with any service that runs on your network, you must understand the
resources needed and the implications of enabling multicast.

Multicast Overview

ust as blue, green, and red are different and each has its own place

within the spectrum of visible light, unicast, broadcast, and multicast are dif-
ferent in that each is used to achieve a specific purpose or fulfill requirements

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