Networking Notes

Introduction

A collection of two or more computers interconnected by the telephone lines, co-axial cable, satellite links, radio and microwave transmission and some other communication techniques.  A computer network is a group of computers that are connected together and that communicate with one another for a common purpose.

Although the computer industry is young compared to anther industries (e.g., automobiles air transportation), computer have made spectacular progress in a short time.  During the first two decades of their extrinsic, computer system highly centralized, usually a single large room.  A medium size company or university might have had one or two computers, while large instructions had at most a few dozen. The idea that with in 20 years equally powerful computers smaller than postage stamps would be mass produced by the millions was pure science fiction.

The merging of computers & communications has had a profound influence on the way computer systems are organized. The concept of the computer center as a room with a large computer to which users bring their work for processing is now totally obsolete. The old model of single computer serving all of the organizations computational needs has been replaced by one in which a large number of separate but interconnected computers do the job. These systems are called computer networks.

Two computers are said to be interconnected if they are able to exchange information’s. The connection need not be via a copper wire; fiber optics, microwaves, and communication satellites can also be used. By requiring the computer to be autonomous, we which to execute from our definitions systems in which there is a clear master/slave relation. If one computer can forcibly starts , stop, or control another one, the computers are not autonomous. A system with one control unit and many slaves is not a network; nor is a large computer with remote printers and terminals.