1.0 Objectives

The main objectives of this unit are to:

Understand the concepts of data and information.
Explain data communication and its basic components.
Describe the different modes of data flow.
Define computer networks and explain their major categories.
Understand the concept of protocols and their essential elements.
Explain the importance and types of standards in computer networking.

1.1 Introduction

Data communication and networking provide the foundation for exchanging information between computers and other digital devices. They enable devices located in the same room, building, city, country, or even different parts of the world to communicate with one another.

A computer network is a collection of interconnected devices, commonly called nodes, connected through communication links for the purpose of exchanging data and sharing resources.

The fundamental goal of data communication is to ensure that information is transmitted reliably, accurately, and on time from a sender to the intended receiver.

1.2 Data and Information

Data

Data refers to raw facts, figures, symbols, or observations that have not yet been processed into a meaningful form.

Information

Information is data that has been processed, organized, or interpreted so that it becomes meaningful and useful for decision-making.

Example

Marks obtained by all students in an examination = Data
A student’s final result showing Pass or Fail = Information

Key Point:
Data → Processing → Information

In simple terms, data serves as the input, while meaningful information is the output obtained after processing.

1.3 Data Communication

Data communication is the exchange of data between two or more devices through a suitable transmission medium.

A data communication system generally involves both:

Hardware: Sender, receiver, and transmission medium.
Software: Protocols and rules that control communication.

1.3.1 Characteristics of Effective Data Communication

An effective data communication system should possess the following characteristics:

Delivery: Data must be delivered to the correct destination or intended user.
Accuracy: Data must reach the receiver without errors, alteration, or loss.
Timeliness: Data must reach its destination within the required time.
Jitter: Variations in the arrival time of data packets should be minimal, particularly in real-time audio and video communication.

1.3.2 Components of Data Communication

A data communication system consists of five basic components:

Message: The information or data that is to be communicated.
Sender: The device that sends the message.
Receiver: The device that receives the message.
Transmission Medium: The physical or wireless path through which data travels.
Protocol: A set of rules that governs communication between devices.

Key Point:
Successful data communication requires a message, sender, receiver, transmission medium, and protocol.

1.4 Data Representation

Computers can communicate different types of data. The major forms of data representation are as follows:

1. Text

Text consists of letters, words, numbers, and other characters. Computers represent text through coding systems such as:

ASCII
Unicode

2. Numbers

Numerical data consists of digits and mathematical values. Internally, computers represent numbers in binary form (0s and 1s).

3. Images

Digital images consist of tiny picture elements known as pixels. Image quality is influenced by factors such as resolution and color depth.

Common image formats include:

JPG/JPEG
PNG
BMP

4. Audio

Audio represents sound in digital form. Examples include:

Speech
Music
Recorded sound
Radio and digital audio streams

5. Video

Video consists of a sequence of images or frames displayed rapidly to create the impression of motion. It may also contain synchronized audio.

Examples include movies, video lectures, video calls, and animations.

1.5 Data Flow

Data flow refers to the direction in which data moves between two communicating devices.

There are three basic modes of data flow:

1.5.1 Simplex

In simplex communication, data flows in one direction only.

The sender can only send, while the receiver can only receive.

Example:
Keyboard → Computer

1.5.2 Half-Duplex

In half-duplex communication, both devices can send and receive data, but not at the same time.

When one device is transmitting, the other must wait.

Example:
Walkie-talkie

1.5.3 Full-Duplex

In full-duplex communication, both devices can send and receive data simultaneously.

Example:
Telephone or mobile-phone conversation

Quick Comparison:
Simplex = One-way
Half-Duplex = Two-way, one at a time
Full-Duplex = Two-way, simultaneously

1.6 Computer Network

A computer network is a collection of interconnected computers and other devices that communicate with one another and share data, information, and resources.

Networked devices may share:

Files and information
Printers and other hardware
Software and applications
Internet connections
Communication services

Important Features of a Network

A well-designed network should provide:

Performance: Efficient and fast transmission of data.
Reliability: Consistent operation with minimum failures.
Security: Protection of data and network resources from unauthorized access.

1.6.1 Categories of Networks

Networks can be classified according to their geographical coverage.

1. LAN – Local Area Network

A Local Area Network (LAN) covers a relatively small geographical area.

Examples: Office, laboratory, school, building, or campus.

2. MAN – Metropolitan Area Network

A Metropolitan Area Network (MAN) covers a larger area than a LAN and may extend across a city or metropolitan region.

Example: A network connecting different organizational branches across a city.

3. WAN – Wide Area Network

A Wide Area Network (WAN) covers a very large geographical area and may connect networks across cities, countries, or continents.

Example: The Internet is the most prominent example of a global interconnected network.

Remember:
LAN → Small Area
MAN → City/Metropolitan Area
WAN → Large Geographical Area

1.7 Protocol

A protocol is a set of rules and conventions that govern communication between two or more devices on a network.

Protocols determine:

What data should be communicated.
How the data should be communicated.
When the data should be communicated.

Elements of a Protocol

Every communication protocol involves three fundamental elements:

1. Syntax

Syntax refers to the structure or format of data.

It determines how information is arranged and represented during communication.

2. Semantics

Semantics refers to the meaning of each section of data and determines how the information should be interpreted.

3. Timing

Timing determines when data should be sent, the rate at which it should be transmitted, and how communicating devices remain synchronized.

Key Point:
Protocol = Syntax + Semantics + Timing

1.8 Standards in Networking

Networking standards are established specifications, rules, and guidelines that enable devices, software, and communication systems from different manufacturers to communicate effectively.

Standards are important because they promote:

Compatibility
Interoperability
Reliability
Uniformity
Technological development

1.8.1 Types of Standards

1. De Facto Standard

A de facto standard becomes accepted because of widespread use, market practice, or industry adoption rather than formal approval by an official standards organization.

De facto = Standard by practice or widespread acceptance

2. De Jure Standard

A de jure standard is formally approved and recognized by an authorized standards organization or regulatory body.

De jure = Standard by formal approval

1.8.2 Standards Organizations and Bodies

Several organizations contribute to the development, regulation, and implementation of communication and networking standards.

Major Standards Organizations

ISO – International Organization for Standardization
ITU-T – International Telecommunication Union, Telecommunication Standardization Sector
ANSI – American National Standards Institute
IEEE – Institute of Electrical and Electronics Engineers
EIA – Electronic Industries Alliance

Industry Forums

Industry forums have historically supported the development and implementation of networking technologies. Examples include:

ATM Forum
MPLS Forum
Frame Relay Forum

Regulatory Agencies

FCC – Federal Communications Commission

The FCC regulates interstate and international communications in the United States through radio, television, wire, satellite, and cable.

Key Points to Remember

Data consists of raw facts and figures, while information is processed and meaningful data.
Data communication means the exchange of data between two or more devices.
Effective data communication requires delivery, accuracy, timeliness, and minimum jitter.
The five components of data communication are message, sender, receiver, transmission medium, and protocol.
Data may be represented as text, numbers, images, audio, and video.
The three modes of data flow are Simplex, Half-Duplex, and Full-Duplex.
The major network categories are LAN, MAN, and WAN.
A protocol is a set of rules governing communication between devices.
The three basic protocol elements are Syntax, Semantics, and Timing.
Networking standards ensure compatibility and interoperability among different devices and systems.
Standards may be classified as de facto or de jure.
Important standards organizations include ISO, ITU-T, ANSI, IEEE, and EIA.