Data Communication ,Computer Network ,The Uses of a Network ,Types of Networks ,Network Topologies,Transmission Media,Guided Transmission Media ,Wireless Transmission,,INTRODUCTION TO INFORMATION TECHNOLOGY,COMPUTER BASICS,NME

1. UNIT III
INTRODUCTION TO INFORMATION TECHNOLOGY
R.SARASWATHI
SRI AKILANDESWARI WOMENS COLLEGE

2. UNIT III
• Data Communication
• Computer Network
• The Uses of a Network
• Types of Networks
• Network Topologies
• Transmission Media: Guided Transmission Media -Wireless
Transmission

3. Data Communication
• Data communication refers to the exchange of data between a source
and a receiver via form of transmission media such as a wired or
wireless.
• Data communication is said to be local if communicating devices are
in the same building or a similarly restricted geographical area.

4. Data Communication
• Datum mean the facts information statistics or the like derived by
calculation or experimentation.
• The term data used to describe information, under whatever form of
words you will be using.

5. Data Communication
• Characteristics
• Delivery: The data must be deliver in correct order with correct destination.
• Accuracy: The data must be deliver accurately.
• Timeliness: The data must be deliver in a timely manner.late delivered Data
useless.

6. Computer Network
• Open system:
A system which is connected to the network and is ready for
communication.
• Closed system:
A system which is not connected to the network and can’t be
communicated with.

7. Computer Network

8. Computer Network
• A computer network is a system in which multiple computers are
connected to each other to share information and resources.
• Share resources from one computer to another.
• Create files and store them in one computer, access those files from the
other computer(s) connected over the network.
• Connect a printer, scanner, or a fax machine to one computer within the
network and let other computers of the network use the machines available
over the network.

9. THE NETWORK USES
• Hardware
Computer Resources
Disks
Printers
• Software
• Application software
• Ms-word , Ms-Excel
• Anti virus

10. THE NETWORK USES
• Communication
• Email
• Message broadcast

11. Types of Networks
• A computer network is a group of computers linked to each
other that enables the computer to communicate with
another computer and share their resources, data, and
applications.
• A computer network can be categorized by their size.
A computer network is mainly of four types:
• LAN(Local Area Network)
• PAN(Personal Area Network)
• MAN(Metropolitan Area Network)
• WAN(Wide Area Network)

12. Types of Networks

13. LAN(Local Area Network)
• Local Area Network is a group of computers connected to each other in
a small area such as building, office.
• LAN is used for connecting two or more personal computers through a
communication medium such as twisted pair, coaxial cable, etc.
• It is less costly as it is built with inexpensive hardware such as hubs,
network adapters, and ethernet cables.
• The data is transferred at an extremely faster rate in Local Area
Network.
• Local Area Network provides higher security.

14. LAN

15. PAN (Personal Area Network)
• Personal Area Network is a network arranged within an
individual person, typically within a range of 10 meters.
• Personal Area Network is used for connecting the computer
devices of personal use is known as Personal Area Network.
• Personal Area Network covers an area of 30 feet.
• Personal computer devices that are used to develop the
personal area network are the laptop, mobile phones, media
player and play stations.

16. PAN

17. MAN(Metropolitan Are Network)
• A metropolitan area network is a network that covers a larger geographic area
by interconnecting a different LAN to form a larger network.
• Government agencies use MAN to connect to the citizens and private
industries.
• In MAN, various LANs are connected to each other through a telephone
exchange line.
• The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN,
OC-3, ADSL, etc.
• It has a higher range than Local Area Network(LAN).

18. MAN

19. WAN(Wide Area Network)
• A Wide Area Network is a network that extends over a large
geographical area such as states or countries.
• A Wide Area Network is quite bigger network than the LAN.
• A Wide Area Network is not limited to a single location, but it spans
over a large geographical area through a telephone line, fibre optic
cable or satellite links.
• The internet is one of the biggest WAN in the world.
• A Wide Area Network is widely used in the field of Business,
government, and education

20. WAN

21. Network Topologies
• Topology defines the structure of the network of how all
the components are interconnected to each other.

22. Bus Topology
• In case of Bus topology, all devices share single communication
line or cable.
• Bus topology may have problem while multiple hosts sending
data at the same time.
• It is one of the simple forms of networking where a failure of a
device does not affect the other devices. But failure of the
shared communication line can make all other devices stop
functioning.

23. Bus Topology

24. Star Topology
• All hosts in Star topology are connected to a central device,
known as hub device, using a point-to-point connection.
• That is, there exists a point to point connection between hosts
and hub.

25. Star Topology

26. Ring Topology
• In ring topology, each host machine connects to exactly two
other machines, creating a circular network structure.
• When one host tries to communicate or send message to a host
which is not adjacent to it, the data travels through all
intermediate hosts.
• To connect one more host in the existing structure, the
administrator may need only one more extra cable.

27. Ring Topology

28. Transmission Media
• The transmission medium can be defined as a pathway that can
transmit information from a sender to a receiver.
• Transmission media are located below the physical layer and are
controlled by the physical layer.
• Transmission media are also called communication channels.
• Transmission media are of two types −
• Guided Transmission Medium
• Unguided Transmission Medium

29. Transmission Media

30. GUIDED TRANSMISSION MEDIA
• Guided transmission media are also called bounded media or wired
media.
• They comprise cables or wires through which data is transmitted.

31. TWISTED PAIR
• One of the earliest guided transmission media is twisted pair cables. A
twisted pair cable comprises of two separate insulated copper wires,
which are twisted together and run in parallel.
• In telephone lines
• In DSL lines
• In LANs

32. TWISTED PAIR

33. COAXIAL CABLE
• Coax has a central core of stiff copper conductor for transmitting signals. This is covered by an insulating
material.
• The insulator is encased by a closely woven braided metal outer conductor that acts as a shield against noise.
• The outer conductor is again enclosed by a plastic insulating cover.

34. BASE BAND COAXIAL CABLE
• A baseband coaxial cable transmits a single signal at a time at very
high speed.

35. BROAD BAND COAXIAL CABLE
• A broadband coaxial cable can transmit many simultaneous signals
using different frequencies.