This presentation covers, what is a network, types of networks, and different topologies of networking and modes of communication.

1. Networks
BY
NAJEEB SAFI
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NAJEEB SAFI

2. NAJEEB SAFI
Computer Networks
 A computer network or simply a
network is a collection of computers,
printers, scanners and other devices
interconnected by communications
channels.
 It facilitate communication among
users and allows users to share
resources and information.
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3. NAJEEB SAFI
Uses of Networks
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• Computer networks are used everywhere. Computer network mostly
used for the following purposes.
a) Resource Sharing
b) Communication
c) Data Sharing
d) Video Conferencing
e) Internet Service

4. NAJEEB SAFI
Resource Sharing
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• Resource sharing is one the most popular uses of computer networks
in various fields. For example, a printer is share in a network and
hence saves a lot of investment in hardware. Computer connected in a
network can make use of the printer in the network instead of having
separate printers for every computer.

5. NAJEEB SAFI
Communication
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• Communication is one of the biggest advantages provided by the
computer networks. People from the same or different organization
can communicate to exchange the work activities. In
offices/organizations computer networks are serving as the backbone
of the daily communication from top to bottom level of organization.

6. NAJEEB SAFI
Data Sharing
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• Another important advantage of computer networks is the data
sharing. All the data such as documents, files, accounts information,
reports, multimedia, etc. can be shared with the help computer
networks.
• Application sharing is also allowed in many organizations such as
banks and small firms.

7. NAJEEB SAFI
Video Conferencing
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• Before the arrival of the computer networks there was no concept of
the video conferencing.
• LAN and WAN have made it possible for the organizations and
business sectors to call the live video conferencing for important
discussions and meetings.

8. NAJEEB SAFI
Internet Service
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• Computer networks provide internet sharing over the entire network.
• Every single computer attached to the network can experience the high
speed internet.

9. NAJEEB SAFI
Data Transmission Modes
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• the term transmission mode defines the direction of data flow between
two linked devices.
• The manner or way in which data is transmitted from one place to
another is called Data Transmission Mode. There are three ways for
transmitting data from one location to another.
1. Simplex Mode
2. Half-Duplex Mode
3. Full-Duplex Mode

10. NAJEEB SAFI
Simplex Mode
• In simplex transmission, data flow only in
one direction from the sending device to
the receiving device.
• Simplex transmission is used only when
the sending device does not require a
response from the receiving device.
• It means that simplex is unidirectional.
• Radio and T.V transmission are the
examples of simplex mode.
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11. NAJEEB SAFI
Half-Duplex Mode
• In half-duplex transmission, can flow in
both directions from sending device to
receiving device, and back but only in one
direction at a time.
• In this mode data is sent and received
alternatively.
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12. NAJEEB SAFI
Full-Duplex Mode
• In full-duplex mode, data can flow in both
directions at the same time.
• It is the fastest transmission mode of
communication.
• A regular telephone line supports full-
duplex transmission so that both parties
can talk at the same time.
• E.g. regular telephone line supports full-
duplex transmission.
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13. NAJEEB SAFI
Network Architecture
• Network architecture is the design of communication network. It is a
framework for the specification of network’s physical components
and their functional organization and configuration, its operational
principles and procedures, as well as data formats used in its
operation.
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14. NAJEEB SAFI
Types Of Network
• Networks which consist of various combinations of computers, storage
devices, and communication devices, are divided into three main
categories, differing primarily in their geographic range or spatial
distance. They are:
• Local Area Network (LAN)
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)
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15. NAJEEB SAFI
Metropolitan Area
Network
 MAN network covers a larger
geographic area by interconnecting a
different LAN to form a larger
network.
 Government agencies make use
MAN to connect the citizens and
private industries.
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16. NAJEEB SAFI
Wide Area Network
 A wide area network is a network that
extends over a large geographical area
such as states or countries.
 WAN is quite bigger network than the
LAN.
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17. NAJEEB SAFI
Personal Area Network
• PAN is network arranged within an
individual person. Typical within the
range of 10 meters.
• PAN is used to connecting computer or
computing devices for personal use.
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18. NAJEEB SAFI
Network Topologies
• Topology is derived from two Greek words “Topo” and “Logy”.
Where topo means “Place” and logy means “study”.
• In computer networks, a topology is used to explain how a network is
physically connected and the logical flow of information in the
network.
• There are five types of topology, which are discussed one by one
below.
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19. NAJEEB SAFI
1. Bus Topology
• In bus topology, all nodes are connected
to a common communication medium or
central cable.
• The central physical cable that connects
the nodes is called Bus.
• The data is communicated between nodes
in both directions through bus. The
central cable or bus acts like backbone to
link all the devices to the network.
• When a computer send message to a
computer, it also attaches the address of
destination computer and is known as
token passing.
• In bus topology, on both ends terminators
are attached, which stops the network
signals.
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20. NAJEEB SAFI
2. Ring Topology
 Ring network topology is shaped like ring
which is shown in the figure.
 It is like a bus with both ends connected
together.
 All the messages travels in the same
direction from one node to another.
 If it match the address the node will
receive the message, otherwise the
message will be ignored and passed on to
the next until the destination is reached.
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21. NAJEEB SAFI
3. Star Topology
 In star topology all the nodes are
connected to a central device called
switch or hub as shown in fig.
 It is one of the most commonly used
network topology.
 A switch can connect 4, 16, 24 or 32
nodes.
 A switch can be connected to another
switch to expand the network.
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22. NAJEEB SAFI
4. Mesh Topology
 In mesh topology, all the network nodes
are connected to all the other nodes as
shown in figure.
 Message sent on a mesh network, can take
any possible path from source to
destination.
 It is not commonly used since it is costly
and difficult to implement.
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23. NAJEEB SAFI
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NAJEEB SAFI
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THANK YOU