Networks and Communication

Computer Networks and Communications

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Introduction

Sharing of information from one computer to other computer is possible if these computers are connected or linked with each other as network. This tutorial is dedicated to the computer networks and data communication.

Computer Networks

Most computer systems are now connected together in come way to form what is known as network. This ranges from a basic school or home network of only a few computers to large networks such as the Internet.

What is Network?

A computer network is interconnection of two or more computer systems located in a same room, building or at different places. computer network enables the sharing of information, programs and hardware components. 

A computer network in an office, company or in a computer lab connects many computers and other devices such as printers with each other using cables. 

Do you know?

“Internet is a worldwide collection of networks which allows a subscriber to send and receive e-mails, chat or brows the World Wide Web (www) to get information on different topics.”

Components of Computer Network

A computer network consists of the following four basic components:

  • Sending Device 
  • Receiving Device 
  • Transmission Media 
  • Communication Devices

Sending Device

A device that is used to send messages, data, or information to other devices connected to a network is called a sending device. In a computer network a sending device is usually a computer.

Receiving Device

In a computer network, a receiving device receives messages, data, or information from a sending device. The receiving device could be a computer, printer, or storage device. 

Transmission Media

Transmission Media is the channel or path through which the data or information is transferred from one place to another in a computer network. Networks are connected by a wired or wireless transmission medium. 

There are three common types of physical transmission media. 

  • Twisted Pair Cable 
  • Coaxial Cable 
  • Fiber Optics Cable

Twisted Pair Cable

Twisted Pair cables are the most popular transmission media for transferring data on a computer network. They are especially used in Local Area Networks. Twisted pair wires consist of two strands of copper twisted together. 

The twists allow the data signals to travel more as compared to a regular copper wire. The more twists per centimeter. the further the signal can travel Twisted pair cable is of two types:

  • Unshielded Twisted Pair (UTP)

If the wires are unshielded, they are called Unshielded Twisted Pair cables. 

  • Shielded Twisted Pair (STP)

If the wires are shielded, they are called Shielded Twisted Pair cables. 

Characteristics of Twisted Pair Cables

  • It is the least expensive type of cable. 
  • It is easy to install. 

Coaxial Cable

A type of wire that consists of a center wire surrounded by insulation and a shield of braided wire. The shield minimized electrical and radio frequency interference. 

Coaxial cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks. Plastic jacket, insulator, and braided shield in a coaxial cable ensure data transmission without interference from other cables. 

Characteristics of Coaxial Cables

  • It is more expensive than standard telephone wire. 
  • It is much at risk of interference than a twisted pair cable.
  • Its data transfer rate is higher than twisted pair cable. 
  • It is easy to install.

Fiber Optic Cable

Fiber Optic is a type of cable that uses glass (or plastic) threads to transmit data. It consists of a bundle of glass threads each of which is capable of transmitting messages in the form of light waves. 

Fiber optic cable consists of a center glass core surrounded by several layers of protective materials such as cladding and buffer coating. 

Characteristics of Fiber Optic Cable

  • It is more expensive as compared to other cables. 
  • It is difficult to install.
  • The data transfer rater of fiber optic cable is the highest.

Communication Device

Communication devices are used for communication between computers and other devices. The modem is a popular communication device that is used for internet communication. 

The most commonly used communication devices are below:

  • Dialup Modem 
  • Network Interface Card 

Dialup Modem

A dialup MODEM (Modulator-Demodulator) is a communication device. It is used to connect to the internet, exchange information, and send and receive data from one computer to the other. It translates computer information into a form that can be transmitted over telephone lines.

A modem can be located inside or outside the computer.  See below for different types of Modem.

router modem
dialup modem

In computers, information is stored digitally, whereas information transmitted over telephone lines is in the form of analog signals. A modem converts digital signals to analog signals (Modulation) and then analog signals to digital signals (Demodulation) 

Network Interface Card (NIC)

Network Interface Card (NIC) is an expansion card that enables a computer to connect to a network. This number is used to identify the computer on the network. 

A Network Interface Card must be installed in each computer on the network. 

Server and Clients

In a computer network, different computers perform different tasks or roles. According to these tasks and roles, computers can be categorized as either clients or servers.  

Server

A server is a powerful computer that facilitates the whole network by providing a variety of services to the computer or devices connected to the network. These services may include:

  • Processing Data 
  • User authentication 
  • Storing information 
  • Sharing software 
  • Controlling and managing network traffic, etc.

Client

The client is a less powerful computer as compared to the server computer. It relies on servers for resources, such as files, devices, and even processing power. 

Types of Computer Network

The computer networks are categorized into the following three types as given below:

  • LAN (Local Area Network)
  • MAN (Metropolitan Area Network)
  • WAN (Wide Area Network)

LAN (Local Area Network)

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a building or adjacent buildings. LAN is the most common type of network. Local area networks are usually owned by one organization. 

Advantages of LAN

  • Computers can share peripheral devices like printers, storage devices, scanning devices, CD-ROM, etc.
  • Users can save their work centrally on the network server. 
  • Users can communicate with each other and transfer data between computers very easilty. Application packages such as a word processor, spreadsheet, etc. in the server computer can be shared by all users. 

Disadvantages of LAN

  • Special security measures are needed to stop unauthorized users. 
  • LANs need to be maintained by skilled personnel.  

MAN (Metropolitan Area Network)

A large computer network that extends to a city or to a metropolitan region is termed a Metropolitan Area Network or MAN. A MAN connects two or more LANs to form a network spread over the whole city. 

A cable television network in a city is a good example of MAN. 

Advantages of MAN

  • It is bigger than LAN.
  • It transfers data at high speed.

Disadvantages of MAN

  • It is expensive.
  • It is difficult to maintain.

WAN (Wide Area Network)

A Wide Area Network is a very large computer network covering a large geographic area, such as a state, province, country, or the whole world, WANs often connect multiple smaller networks. Many large organizations develop their own private WANs. 

Advantages of WAN

  • It WAN, the users at different locations are connected to a central server. 
  • It is used to monitor distant locations and offices. 

Disadvantages of WAN

in WAN, security is a big issue. 

  • Setting up a network can be an expensive and complicated task. 
  • Management, maintenance, and troubleshooting WAN is a difficult task.

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