chapter 1- NETWORKING (What is a network) ?

NETWORKING -

To communicate in an institution, Over the Internet, some mode of communication, arrangement of communication is required. This communication is accomplished through networking.

Network - A Computer network is a system in which computers are connected to share information and resources. This means that the computers can talk to each other. Computer network allow people and machines to communicate, using a number of services. Networking is done through different communications. Telephone lines, wires, cables, satellite links, radio frequency are various means of communications.

Need of Network -

There are various reasons which favour need of Network:

* To share data at different location of the organisation.

* To share information with other people on the network.

* To make quick line with the other person using network.

* To communicate in the form of mail message and chatting.

* To gain knowledge from the worldwide resources using the Internet.

Benefits of Network -

The benifits of networking in homes are:

* File sharing is possible. Not only can you share photos, music files and documents, you can also save copies of all your important data on a different computer.

* Printer/peripheral shareing is possible. It is easy to other set up all of the computers to share a single printer. Other computer peripherals can be shared similarly such as network scanners, Web cams and CD burners.

* Internet connection shareing is possible. Multiple family members or staff members in office, can access the Internet simultaneously without having to pay an ISP for multiple accounts.

* Multi - player games can be played.

* Many popular home computer games support LAN mode where friends and family can play together, if they have their computers networked.

Types of Networks -

There are mainly three types of Networks:

* LAN

* WAN

* MAN

Local Area Network (LAN) _

LAN is a system in which computers are interconnected. Under this technology, a number of terminals can be used in the whole building at various places with sharing means. All the terminals are connected to a main computer called server. With the use of this facility the bank can provide multi-services at any computer of the bank.

Elements of LAN :

LAN has following elements:

1. Server.                             2. Workstations

3. Network Internet Unit.  

4. Communication Channels

* Server -

It is the main computer which acts as a host and provides data, software etc. To the other terminals linked with it. It serves the work stations. A LAN can also have more than one server.

* Workstation -

Workstations means computer/s attached to LAN. Without workstations LAN cannot exist. It is not necessary that workstations should have hard disks.

* Network Interface Unit -

It establishes connection between the Networks. NIU is a device which is attached to each workstation and server.

* Communication Channels -

It means connecting with the cables. Three types of cables are used in LAN installations which are as following.

(1) Twisted pair cables: These are like telephone cables.

(2) Co-axial Cables : These are like TV cables.

(3) Fibre Optical Cables: These are newly introduced mode of plastic or glass.

These are durable.

Uses of LAN -

* Effective Customer service -

LAN is very beneficial in costomer service aspects. The customer has not to go to a particular terminal at a particular seat. He can approach to any terminal for multipurpose.

* Shared use of Hardware and Software -

Hardware and software can be shared. We do not need equal number of printers for equal number of terminals. By using some commands printout can be taken even in another room where the printer is kept. Similarly we have not to load the software in each terminal.

* Communication -

Terminals can do the job of intercom. Messages can be transferred across the users sitting in other rooms instantaneously.

* Security -

It is noted that users have users but the LAN system has in-built security and it is virtually not possible to get hold of other users.

* Additions/Removal of Terminals-

As and when needed, new terminals can be attached to the existing ones and old terminals can be detached.

Wide Area Network (WAN)-

It is a computer network that covers a far wider area than a LAN ( local Area Network). WANs cover cities, countries, continent and the whole world.

A WAN is formed by linking LANs together. For example, several major LANs in a city can cannot together forming a WAN . This Network uses telephone lines, satellite communication, microwave transmission etc. These transmission media are linked with router. A router is a device which interconnects two or more computer network.

Metropolitan Area Network -

It is a computer network usually spanning a campus or a city, which typically connects a few local Area Network. A MAN often provides efficient connections to a wide Area Network (WAN). Optical fibre is used in MAN. It is larger than LAN but smaller than WAN.

Cable TV network is a good example of MAN.

Types of Networks on The Basis of connectivity -

Depending on the needs of an organization, a Network May span a geographical divide or allow for interconnection between persons and devices within the same building. In this day and age, this interconnectivity is a matter of great importance because it facilitates the efficient running of an organization or helps it to maintain a competitive edge. 

Networks are of three types;. Internet, Intranet, and Extranet.

Internet -

Internet is a worldwide Network of Networks. It is also the Network of Networks that connects millions computers (called hosts).

When you connect two or more computers you form a Network. Computers in the Network can communicate with each other. Thousands of different computer types exist within this Internet work. These computers use variety of Network software. Internet is a Network of Networks that connects computers all over the world.

Intranet -

Intranet is a application of Internet to a closed networking system. It allows the organisation in a cost efficient manner to connect with the corporate Networks and distributed information.

The growth of intranet in the corporates is on tremendous increase. It is a cost efficient way to use internet-related services.

Extranet -

Extranet is that Network which links some of the Intranets of a company with its partners, customers etc. Who can access selected Intranet websites and company's database.

Communication devices -

Repeater -

A repeater connects two segments of your network cable. It retimes and regenerates the signals to proper amplitudes and sends them to the other segments.

Bridge -

A bridge is a device that connects one local Area Network (LAN) to another local Area Network that uses the same protocol.

Router -

A router is a device that determines the next Network point to which a packet (data) should be forwarded toward its destination. The router is connected to at least two Network and decides which way to send each information packet based on its current understanding of the state of the Network it is connected to. A router is located at gateways, the places where two or more Network connect, and are the critical device that keeps data flowing between Networks and keeps the Networks connected to the Internet.

Hub -

A Network hub is a device which is used to connect multiple twisted pair or fiber optic Ethernet devices together and makes them act as a single Network segment. In the present scenario, Network switches are replacing hubs are still seen in older installations and more specialised applications.

Server -

A server is itself a computer that provides services or resources to other computers connected with it by some networking mechanism. It is designated for running a specific server application.

When a server starts, it opens the door for incoming requests from its clients, but it never initiates a service until it is requested to do so. When server starts, it runs infinitely unless a problem arises. It waits for incoming requests from clients and when a request Aries, it responds to the request.

Switch -

When we have multiple devices, we face a problem to connect them to make one _on_one communication possible. The number and length of the links required for connecting them needs too much infrastructure.majority of the links remain idle for most of the time. A Network switch is a computer networking device that connects Network segments.

A switched Network consist of a series of interlinked nodes called switches. A switch may be hardware or a software device capable of creating temporary connection between two or more devices linked to the switch but not to each other.

LAN Card-

A local Area Network (LAN) card is used to provide access computers and servers on network. It works by exchanging signal with a router, which transmits the signals over a physically with line.

A LAN card communicates with the router. The computer converts data into binary form and sends it to the LAN Card, which in turn broadcasts the signal to be picked up by the router. The router sends the information in the form of packets of information and bundles information for return to the computer via the LAN cards in the same way.

Modem -

The word MODEM consist of MO+DEM. MO stand of MOdulator and DEM for Demodulator. The conversation of digital signals to analog signals is called modulation and the reverse process is called demodulation. Modems are connected both at sending and receiving ends. The modulator of sender changes the bit pattern to analog signals. The modem is connected between a terminal and telephone line. The signal is sent through telephone line and the modem at receiving end demodulates the wave pattern into digital signals and These signals are converted into output or stored in computer.