presentation on copy
TRANSCRIPT
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
19