PRESENTATION ON

First slide 1

Data communication

Data communication technologies deal with means and methods of data transfer from one location to another. Marriage between

computing and data communication technologies is one of the most exciting developments that has revolutionized

information age. This development gave birth to computer network.

Second slide 2

COMPUTER NETWORKS

A computer network is a network of computers that are geographically distributed, but connected in a manner to enable meaningful transmission and exchange of data among them.

Third slide3

TYPES OF COMPUTER NETWORKS

Based on characteristics such as geographic distribution of nodes, data rate, error rate, communication link, ownership, and communication cost, networks are classified broadly into two types:

LAN AND WAN.

Networks that share some of the characteristics of both LANs and WANs are sometimes refered to as MANs.

Fourth slide 4

LANA lan connects computers located near each other. In

some cases “local” means within the same room orbuilding. In other cases “local” refers to computerslocated several miles apart.

WANIn contrast WAN consists of computers in different cities,

states or even countries. We can refer to WAN as long-haulnetworks because of the great distance the information they

exchange must travel.

Fifth slide 5

A sender (source) that creates and sends a

message.

Sixth slide6

A medium that carries the message.

A receiver (sink) that receives the message.

Basic elements of communication system are

graphically shown here.

Basic elements of any communication system are shown in this figure:

SEVENTH SLIDE 7

SENDER(SOURCE)

RECEIVER(SINK)

MEDIUMCarries message

Data transmission modes

Three modes of data transmission are:

EIGHTTH SLIDE 8

simplex Half-duplex

Full-duplex

NINETH SLIDE

9

There are three modes of data transmission. These are

simplex

Half-duplex

Full-duplex

simplex: A simplex communication system can transmit data in one direction only. Devices connected to such a circuit are either send only(such as keyboard) or receive only (as printer). As in figure below

sender receiversimplex

HALF-DUPLEX

A half-duplex communication system can transmitdata in both directions, but in only one direction only at atime. Hence it can alternately send and receive data. Exampleis wireless set.

TENTH SLIDE

10

Sender or

receiver

Sender or

receiver

Half duplex

FULL-DUPLEXA full-duplex system needs to switch direction each

time the direction of data transfer reverses. A full-duplex communication system allows data to flow in both the directions simultaneously.

ELEVENTH SLIDE11

SenderAnd

receiver

ReceiverAnd

Sender

Full-duplex

DATA TRANSMISSION MEDIA

There are several types of physical channels (communication media) through which data can be transmitted from one point to another. Some of the most commonly used data transmission media are

Twisted pair wire (UTP cable).

Coaxial cable.

Microwave system.

Communication satellite.

Optical fibres.

TWELVETH SLIDE 12

NETWORK TOPOLOGIES

Network topology refers to a network shape or geometicarrangement of computers. Topology gives a way to compare andclassify different networks. Choice of a topology for a computernetwork depends on a combination of factors such as:

Desired performance of the system.

Desired realiability of the system.

Size of the system.

Expandability of the system.

Availability of communication lines.

THIRTEENTH SLIDE 13

FOUR MAJOR TOPOLOGIES

FOIRTEEHTH SLIDE 14

STAR TOPOLOGY

FIFTEENTH SLIDE

15

HOST NODE

COMPUTER

1

COMPUTER

2

COMPUTER

3

COMPUTER

4

RING TOPOLOGY

COMP

1

COMP

2

COMP

3COMP

4

COMP

5

16

COMPLETELY CONNECTED NETWORK

SEVENTEENTH SLIDE 17

COMP1

COMP5

COMP2

COMP4

COMPLETELY CONNECTED NETWORK

COMP3

MULT-ACCESS BUS NETWORK

EIGHTEENTH SLIDE 18

COMP1

COMP3

COMP4

FOURTH TOPOLOGY

COMP2

THANK YOU

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