Objective
At the end of this module, you should be able to:
- Define data, information and communication
- Know communication system and its basic elements
- Get an overview of a computer network
- Learn the advantages of computer networks
- Understand and explain the different types of networks
- Differentiate Virtual Private Network(VPN), Intranet and Extranet
- Identify different network topologies and their features
- Distinguish different network architectures
- Identify the network devices and their uses
Introduction
Today most of our businesses and daily activities depend on Information; therefore we are highly dependant on computers, communication devices and services that help in storing and processing information. There are more than 100 million computers and terminals at work in the world today. The overwhelming need of organizations and their workers now is for connectivity, for integration and for ease of access to information. The technology that is bringing all these together and making it possible is networking.
Data Communication
Data communication concerns itself with the transmission (sending and receiving) of information between two parties. This means sending information between machines which are connected together by physical wires or radio links (wireless). Physical wire can be twisted copper wire pair, coaxial cables or even fibre optics.
is an example of a wired network. All the computers are connected via a cable (wire) to a central Hub or Switch. Folder and printer can be shared over the network. Such network is also called Ethernet.
Figure1.4 is an example of wireless network, where connections between computers are done with help of radio signals using Wireless Access Point rather than physical wire.
An access point (AP) for wireless Ethernet is a device that communicates with wireless Ethernet cards and wireless-enabled notebook computers to transmit data via radio signals.
Communication System
There are FOUR basic elements involved in a Communication System.
Sender: Sender is the party which initiates the communication.Medium: Medium is the mechanism by which the communication is conveyed to the receiver.
Receiver: Receiver is the one who receives the signal sent by the sender.
Message: Message is the information content that is transferred between the sender and the receiver via the medium.
Network
network can be defined as a group of stations (computers, telephones or other devices) connected by communication facilities for exchanging information. A network can be connected to other network thus making a bigger network. For example, local telephone exchanges connect to the city main exchange, which itself connects to the main national telephone exchange. Sometimes a network can be a part of other networks; such network is called a sub-network
Why use Computer Networks
Sharing Information:
Once the network has been completed, information sharing can be easy. Information can be shared by posting it on a website, forum or discussion group.
Sharing Hardware:
Costly hardware like laser printers and DVD writers can be easily shared among office workers/departments to reduce cost. A common sharing device in an organization is the laser printer. Centralizing Administration and Support:
Networking PCs and devices reduce the need for decentralized IT resources by providing a single point of management for all users and computers. All authorized user accounts and necessary security features can be controlled by the network administrator from a centralized server.
Communication
Types of Networks
Depending on the size and coverage area of the network, it can be classified into following groups:
Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)