INTRODUCTION TO COMPUTER NETWORKS

A Computer network consists of two or more autonomous computers that are linked (connected) together in order to:

• Share resources (files, printers, modems, fax machines).

• Share Application software like MS Office.

• Allow Electronic communication.

• Increase productivity (makes it easier to share data amongst users).

The Computers on a network may be linked through Cables, telephones lines, radio waves, satellites etc.

A Computer network includes, the network operating system in the client and server machines, the cables, which connect different computers and all supporting hardware in between such as bridges, routers and switches. In wireless systems, antennas and towers are also part of the network.

Computer networks are generally classified according to their structure and the area they are localised in as:

• Local Area Network (LAN): The network that spans a relatively small area that is, in the single building or campus is known as LAN.

• Metropolitan Area Network (MAN): The type of computer network that is, designed for a city or town is known as MAN.

• Wide Area Network (WAN): A network that covers a large geographical area and covers different cities, states and sometimes even countries, is known as WAN.

CLASSIFICATION OF NETWORKS

Depending on the transmission technology i.e., whether the network contains switching elements or not, we have two types of networks:

·             Broadcast networks.

·             Point-to-point or Switched networks.

Broadcast networks have a single communication channel that is shared by all the machines on the network. In this type of network, short messages sent by any machine are received by all the machines on the network. 

The different types of Broadcast networks are:

1)               Packet Radio Networks.

2)               Satellite Networks.

3)               Local Area Networks.

Point-to-Point or Switched Networks

Point–to-point or switched, networks are those in which there are many connections between individual pairs of machines. In these networks, when a packet travels from source to destination it may have to first visit one or more intermediate machines.

Routing algorithms play an important role in Point-to-point or Switched networks because often multiple routes of different lengths are available.

An example of a switched network is the international dial-up telephone system. The different types of Point-to-point or Switched networks are:

• Circuit Switched Networks.
• Packet Switched Networks.

NETWORK TOPOLOGY

Some of the most common network topologies are:

• Bus topology
• Star topology
• Ring topology
• Tree topology 
• Mesh topology
• Cellular topology