1
Unit 1. Introduction to data
communications and networking
1
NETWORKING FUNDAMENTALS
Unit Structure
1.0 Objectives
1.1 Introduction
1.2 Data & Information
1.3 Data Communication
1.3.1 Characteristics of Data Communication
1.3.2 Components of Data Communication
1.4 Data Representation
1.5 Data Flow
1.5.1. Simplex
1.52. Half Duplex
1.5.3. Full Duplex
1.6 Computer Network
1.6.1 Categories of a network
1.7 Protocol
1.7.1 Elements of a Protocol
1.8 Standards In Networking
1.8.1 Concept of Standard
1.8.2 Standard Organizations in field of Networking
1.9 Review Questions
1.10 References
1.0 OBJECTIVES:
Introduce the readers to data communication and its
fundamentals
Define networks
Define protocols
Standards in networking
, 2
1.1 INTRODUCTION
This chapter provides an introduction to Computer networks and
covers fundamental topics like data, information to the definition
of communication and computer networks.
The main objective of data communication and networking is to
enable seamless exchange of data between any two points in
the world.
This exchange of data takes place over a computer network.
1.2 DATA & INFORMATION
Data refers to the raw facts that are collected while information
refers to processed data that enables us to take decisions.
Ex. When result of a particular test is declared it contains data
of all students, when you find the marks you have scored you
have the information that lets you know whether you have
passed or failed.
The word data refers to any information which is presented in a
form that is agreed and accepted upon by is creators and users.
1.3 DATA COMMUNICATION
Data Communication is a process of exchanging data or
information
In case of computer networks this exchange is done between
two devices over a transmission medium.
This process involves a communication system which is made
up of hardware and software. The hardware part involves the
sender and receiver devices and the intermediate devices
through which the data passes. The software part involves
certain rules which specify what is to be communicated, how it
is to be communicated and when. It is also called as a Protocol.
The following sections describes the fundamental
characteristics that are important for the effective working of
data communication process and is followed by the components
that make up a data communications system.
1.3.1 Characteristics of Data Communication
The effectiveness of any data communications system depends
upon the following four fundamental characteristics:
, 3
1. Delivery: The data should be delivered to the correct
destination and correct user.
2. Accuracy: The communication system should deliver the data
accurately, without introducing any errors. The data may get
corrupted during transmission affecting the accuracy of the
delivered data.
3. Timeliness: Audio and Video data has to be delivered in a
timely manner without any delay; such a data delivery is called
real time transmission of data.
4. Jitter: It is the variation in the packet arrival time. Uneven Jitter
may affect the timeliness of data being transmitted.
1.3.2 Components of Data Communication
A Data Communication system has five components as
shown in the diagram below:
Fig. Components of a Data Communication System
1. Message
Message is the information to be communicated by the sender to
the receiver.
2. Sender
The sender is any device that is capable of sending the data
(message).
3. Receiver
The receiver is a device that the sender wants to communicate the
data (message).
4. Transmission Medium
It is the path by which the message travels from sender to receiver.
It can be wired or wireless and many subtypes in both.
, 4
5. Protocol
It is an agreed upon set or rules used by the sender and
receiver to communicate data.
A protocol is a set of rules that governs data communication.
A Protocol is a necessity in data communications without
which the communicating entities are like two persons trying
to talk to each other in a different language without know the
other language.
1.4 DATA REPRESENTATION
Data is collection of raw facts which is processed to deduce
information.
There may be different forms in which data may be represented.
Some of the forms of data used in communications are as follows:
1. Text
Text includes combination of alphabets in small case as well
as upper case.
It is stored as a pattern of bits. Prevalent encoding system :
ASCII, Unicode
2. Numbers
Numbers include combination of digits from 0 to 9.
It is stored as a pattern of bits. Prevalent encoding system :
ASCII, Unicode
3. Images
―An image is worth a thousand words‖ is a very famous saying.
In computers images are digitally stored.
A Pixel is the smallest element of an image. To put it in simple
terms, a picture or image is a matrix of pixel elements.
The pixels are represented in the form of bits. Depending upon
the type of image (black n white or color) each pixel would
require different number of bits to represent the value of a pixel.
The size of an image depends upon the number of pixels (also
called resolution) and the bit pattern used to indicate the value
of each pixel.
Example: if an image is purely black and white (two color) each
pixel can be represented by a value either 0 or 1, so an image
made up of 10 x 10 pixel elements would require only 100 bits in
memory to be stored.
On the other hand an image that includes gray may require 2
bits to represent every pixel value (00 - black, 01 – dark gray, 10
Unit 1. Introduction to data
communications and networking
1
NETWORKING FUNDAMENTALS
Unit Structure
1.0 Objectives
1.1 Introduction
1.2 Data & Information
1.3 Data Communication
1.3.1 Characteristics of Data Communication
1.3.2 Components of Data Communication
1.4 Data Representation
1.5 Data Flow
1.5.1. Simplex
1.52. Half Duplex
1.5.3. Full Duplex
1.6 Computer Network
1.6.1 Categories of a network
1.7 Protocol
1.7.1 Elements of a Protocol
1.8 Standards In Networking
1.8.1 Concept of Standard
1.8.2 Standard Organizations in field of Networking
1.9 Review Questions
1.10 References
1.0 OBJECTIVES:
Introduce the readers to data communication and its
fundamentals
Define networks
Define protocols
Standards in networking
, 2
1.1 INTRODUCTION
This chapter provides an introduction to Computer networks and
covers fundamental topics like data, information to the definition
of communication and computer networks.
The main objective of data communication and networking is to
enable seamless exchange of data between any two points in
the world.
This exchange of data takes place over a computer network.
1.2 DATA & INFORMATION
Data refers to the raw facts that are collected while information
refers to processed data that enables us to take decisions.
Ex. When result of a particular test is declared it contains data
of all students, when you find the marks you have scored you
have the information that lets you know whether you have
passed or failed.
The word data refers to any information which is presented in a
form that is agreed and accepted upon by is creators and users.
1.3 DATA COMMUNICATION
Data Communication is a process of exchanging data or
information
In case of computer networks this exchange is done between
two devices over a transmission medium.
This process involves a communication system which is made
up of hardware and software. The hardware part involves the
sender and receiver devices and the intermediate devices
through which the data passes. The software part involves
certain rules which specify what is to be communicated, how it
is to be communicated and when. It is also called as a Protocol.
The following sections describes the fundamental
characteristics that are important for the effective working of
data communication process and is followed by the components
that make up a data communications system.
1.3.1 Characteristics of Data Communication
The effectiveness of any data communications system depends
upon the following four fundamental characteristics:
, 3
1. Delivery: The data should be delivered to the correct
destination and correct user.
2. Accuracy: The communication system should deliver the data
accurately, without introducing any errors. The data may get
corrupted during transmission affecting the accuracy of the
delivered data.
3. Timeliness: Audio and Video data has to be delivered in a
timely manner without any delay; such a data delivery is called
real time transmission of data.
4. Jitter: It is the variation in the packet arrival time. Uneven Jitter
may affect the timeliness of data being transmitted.
1.3.2 Components of Data Communication
A Data Communication system has five components as
shown in the diagram below:
Fig. Components of a Data Communication System
1. Message
Message is the information to be communicated by the sender to
the receiver.
2. Sender
The sender is any device that is capable of sending the data
(message).
3. Receiver
The receiver is a device that the sender wants to communicate the
data (message).
4. Transmission Medium
It is the path by which the message travels from sender to receiver.
It can be wired or wireless and many subtypes in both.
, 4
5. Protocol
It is an agreed upon set or rules used by the sender and
receiver to communicate data.
A protocol is a set of rules that governs data communication.
A Protocol is a necessity in data communications without
which the communicating entities are like two persons trying
to talk to each other in a different language without know the
other language.
1.4 DATA REPRESENTATION
Data is collection of raw facts which is processed to deduce
information.
There may be different forms in which data may be represented.
Some of the forms of data used in communications are as follows:
1. Text
Text includes combination of alphabets in small case as well
as upper case.
It is stored as a pattern of bits. Prevalent encoding system :
ASCII, Unicode
2. Numbers
Numbers include combination of digits from 0 to 9.
It is stored as a pattern of bits. Prevalent encoding system :
ASCII, Unicode
3. Images
―An image is worth a thousand words‖ is a very famous saying.
In computers images are digitally stored.
A Pixel is the smallest element of an image. To put it in simple
terms, a picture or image is a matrix of pixel elements.
The pixels are represented in the form of bits. Depending upon
the type of image (black n white or color) each pixel would
require different number of bits to represent the value of a pixel.
The size of an image depends upon the number of pixels (also
called resolution) and the bit pattern used to indicate the value
of each pixel.
Example: if an image is purely black and white (two color) each
pixel can be represented by a value either 0 or 1, so an image
made up of 10 x 10 pixel elements would require only 100 bits in
memory to be stored.
On the other hand an image that includes gray may require 2
bits to represent every pixel value (00 - black, 01 – dark gray, 10
