Communication is the desire
The transmission of data from
one computer to another, or from
one device to another.
What is Communication?
Data in a computer is transmitted to another
computer located across continents almost
instantaneously using telephone,microwave or
A large number of computers are
interconnected by copperwire,fibre
optic cable,microwave and infrared or
A system consisting of connected
nodes made to share data, hardware
and software is called a Computer
Reasons for Networking
Sharing of Resources:
Primary goal of a computer network is to share
resources. For example several PCs can be connected to
a single expensive line printer.
Information on a single computer can be accessed by
other computers in the network.Duplication of data file
on separate PCs can be avoided.
When several PCs are
connected to each other
messages can be sent
From a remote location a mobile salesman
relay important messages to the central
office regarding orders. Relevant databases
are updated and the business commitments
Applications of Network
Electronic data interchange
Financial services,marketing and sales
Reservation of Airlines, trains, Theatres
Several educational institutions,
businesses and other organizations have
discovered the benefits of computer
Users can share data and programmes.
They can co-operate on projects to
maximize the usage of available expertise
Benefits of Network
Effective handling of personal
Allowing several users to access
simultaneously important programs and data
Making it easy for the users to keep all
critical data on shared storage device and
safeguard the data
Allowing people to share costly equipment.
The computer communication should
ensure safe,secure and reliable data
Safe: The data received is the same as the
Secure: The data being transferred cannot be
changed either will fully or accidentally.
Reliable: Both the sender and the receiver
knows the status of the data sent.Thus the sender
knows whether the receiver got the correct data
Local Area Network (LAN)
A local area network is a computer network that connects computer in a
limited area such as home, school, office building. A LAN is useful for
sharing resource like files, printers, games and other application.
Metropolitan Area Network(MAN)
A metropolitan area network is a network that
interconnects users with computer resource in a
geographical area or a region than that covered by even
a large local area network but smaller area network
covered by WAN .
It is used for interconnection of several local area
networks by bridging them backbone line.
Wide Area Network(WAN)
A WAN spans a large geographical area, such as
a state, country.
WAN connects multiple smaller networks such
as local area network or metro area networks.