Data communications and networking.pdf

Data communications and networking are changing the way wedo business and the way
welive. Business decisions have to be madeever morequickly, and the decision makers
require immediate access to accurate information. Why wait a weekfor that report
from Germany to arrive by mail whenit could appear almost instantaneously through
computer networks? Businesses today rely on computer networks and internetworks.
But before weask how quickly wecan gethooked up, weneed to know how networks
operate, what types of technologies are available, and which design best fills which set
of needs.

The developmentof the personal computer broughtabout tremendous changes for
business, industry, science, and education. A similar revolution is occurringin data
communications and networking. Technological advances are makingit possible for
communications links to carrymoreand faster signals. Asa result, services are evolving
to allow use of this expanded capacity. For example, established telephone services
such as conference calling,call waiting,voicemail,and caller ID have been extended.
Research in data communications and networking has resulted in new technolo-
gies. One goal is to be able to exchange data such as text, audio, and video from all
points in the world. Wewant to access the Internet to download and upload information
quicklyand accurately and at any time.
This chapteraddresses four issues: data communications,networks, the Internet,
and protocols and standards. First wegive a broad definition of data communications.
Thenwedefine networks as a highway on which data can travel. The Internet is dis-
cussed as a goodexample of an internetwork (i.e., a network of networks). Finally,we
discuss different types of protocols,the difference between protocols and standards,
and the organizations that setthose standards.