Introduction

Computer Network

A network also known as data network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the networks. Computer network is a telecommunication channel through which we can share our data. The best example of computer network is Internet.

Data Communication

Data communications are the transfer of data from one device to another device via some form of transmission medium such as a wire, cable...etc. For data communications to occur, the communicating devices must be part of a communication system, made up of a combination of hardware (physical equipment) and software (programs). The effectiveness of data communication system depends on four fundamental characteristics:-

Delivery:- The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user.

Accuracy:- The system must deliver the data accurately. Data that have been altered in transmission and left uncorrected are unusable.

Timeliness:- The system must deliver data in a timely manner. Data delivered late are useless. In the case of video and audio, timely delivery means delivering data as they are produced, in the same order that they are produced, and without significant delay. This time of delivery is called real time transmission.

Jitter:- Jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of audio or video packets. For example, let us assume that video packets are sent every 30ms. If some of packets arrive with 30ms delay and others with 40ms delay, an uneven quality in the video in the result.

Data Communication Components

Data communication is made up of a five components:-

Message:- The message is the information or data to be communicated between sender and receiver. Popular forms of data or information include text, numbers, pictures, audio, and video.

Sender:- The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, video camera etc.

Receiver:- The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, television etc.

Transmission Medium:- The transmission medium is the physical path by which a message travels from sender to receiver. It can be a twisted-pair wire, coaxial cable, fiber-optical cable, radio waves etc.

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