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packet to all the hosts. When a copy of this packet arrives at each end device, the devices recognize that it is addressed to all the devices and processes the packet.

Figure 6-7       Broadcast Communication

Source: 172.16.4.1

Destination: 255.255.255.255

A
172.16.4.1	B	C	172.16.4.253
	172.16.4.2	172.16.4.3

As presented earlier, when a packet is broadcast, it uses resources on the network and forces every host on the network that receives the packet to process it. Therefore, broadcast traffic should be limited so that it does not adversely affect the performance of the network or devices. Because routers separate broadcast domains, subdividing networks with exces-sive broadcast traffic can improve network performance.

Multicast Communication and Addresses

Multicast transmission is designed to conserve the bandwidth of the IPv4 network. It reduces traffic by allowing a host to send a single packet to a selected set of hosts. To reach multiple destination hosts using unicast communication, a source host would need to send an individual packet addressed to each host. With multicast, the source host can send a sin-gle packet that can reach thousands of destination hosts.

The following are some examples of multicast transmission:

■   Video and audio broadcasts

■   Routing information exchange by some routing protocols

■   Distribution of software

■   News feeds