Routable protocols enable the transmission of data between
computers in different segments of a network. However, high
volumes of certain kinds of network traffic, such as the
deployment of multimedia applications, can affect network
efficiency because it slows down transmission speed. The amount
of network traffic generated varies with the three types of data
transmissions: unicast, broadcast, or multicast. To understand
how each transmission type affects network traffic, you must be
familiar with the characteristics of each type of transmission.
Unicast
In a unicast transmission, a separate copy of the data is sent
from the source to each client computer requesting it. No other
computer on the network needs to process the traffic. However,
unicast transmission is not as efficient when multiple computers
request the same data because the source transmits multiple
copies of the data. Unicast transmission works best when just a
small number of client computers request the data. Unicast
transmission is also referred to as directed transmission. Most
traffic on networks today is unicast.
Broadcast
When data is broadcast, a single copy of the data is sent to all
clients on the same network segment as the sending computer.
However, if that data must be sent to only a portion of the
network segment, broadcast transmission is not an efficient
transmission method because data is sent to the whole segment
irrespective of whether it is required. This needlessly slows
the performance of the network because each client must process
the broadcast data.
Multicast
In a multicast transmission, a single copy of the data is sent
only to client computers requesting it. Multiple copies of data
are not sent across the network. This minimizes the network
traffic and enables the deployment of multimedia applications on
the network without overburdening the network. Many Internet
services use multicasting to communicate with client computers.
