This document provides an overview of computer networks. It discusses different types of networks including LAN, MAN, WAN and examples of their usage. Key topics covered include network hardware, services, cables, architectures, topologies and protocols. Specific network topologies such as bus, star, ring, tree and mesh are defined along with their advantages and disadvantages. The importance of networking and reasons to share networks are also mentioned.

1. Network of Networks
Computer Networks

2. Types of networks
Comparison of different networks
Difference between
LAN MAN WAN
Internet
Define Computer Networks
A Network of Networks
State Importance of Computer
network and communication
Network classification
p. 1.2
LEARNING OUTCOMES

3. The Digital Revolution
Where can you find computers?
 Computers are everywhere
Computer Networks

4. INTERNET
 A network formed by
the co-operative
interconnection of a
large no. of computer
networks.
 Since Internet is
formed by the
interconnection of
no. of networks,
sometimes its also
called as network of
networks
Computer Networks

5.  E-mail
 Information
 Shopping
 Meeting
people
 Entertainment
 E-mail
 Information
 Shopping
 Meeting people
 Entertainment
Networks and the Internet
Why do users access the Internet?
p. 1.17 Fig. 1-18
Computer Networks

6. Step 1
Step 2
Step 1
Step 3
Step 2
Step 1Step 1
Step 2
Step 3
Step 4
How do you connect
to the Internet and
display a Web page?
Networks and the Internet
Step 4 : The
Web browser
locates the
Web site for
the entered
address and
displays a
Web page on
your screen
Step 3 : Enter
the address of
the Web site
you wish to
visit
Step 2 : A Web
browser such
as Internet
Explorer
displays a Web
page on your
screen
Step 1 : Use
your computer
to make a local
telephone call
to an online
service
Computer Networks

7. COMPUTE
R NETWORK
What is…

8. Computer network
• A computer
network is a system
of interconnected
computers and
peripheral devices.
• For example, it may
connect computers,
printers, scanners
and cameras.
Computer Networks

9. Advantages and disadvantages
of computer network
Advantages of computer network:-
 Speed
 Cost
 Security
 Centralized software
management
 Resources sharing
 Electronic mail
 Flexible access
Disadvantages of computer:-
network:-
 Expensive to install
 Requires administrative time
 File server may fail
 Cables may break
Computer Networks

10. WHAT ARE THE REASONS to…
SHARE NETWORKS

11. Networks
What are the reasons to network?
Software
programs
Hardware
devices
Data
Information
To save
time and
money
To share
resources
Computer Networks

12. COMMUNICATION
S
What is…

13. Communications
• Communications is
about the transfer of
information from a
sender, across a
distance, to a
receiver.
• Communication is an
act of transmitting
messages.
Computer Networks

14. Computer Network
Communication
• We transmit information or data by using
two types of signals, namely analog and
digital.
• Computers communicate with digital
signals.
• The older forms of communications
technology, such as telephones and radios,
use analog signals.
Computer Networks

15. Computer Networks
Network Classification
• Connection method
Computer networks can also be classified according to the hardware and software
technology that is used to interconnect the individual devices in the network, such as
Optical fiber, Ethernet, Wireless LAN, Home-PNA, Power line communication .
• Scale
Based on their scale, networks can be classified as Local Area Network (LAN),
Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area
Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN),
Storage Area Network (SAN), etc.
• Functional relationship (network architecture)
Computer networks may be classified according to the functional relationships
which exist among the elements of the network, e.g., Active Networking, Client-
server and Peer-to-peer (workgroup) architecture.
• Network topology
Computer networks may be classified according to the network topology upon
which the network is based, such as bus network, star network, ring network, mesh
network, star-bus network, tree or hierarchical topology network.

16. Types of
NetworksComputer Networks
• Local area network(LAN)
• Metropolitan area network(MAN)
• Wide area network(WAN)
• Personal area network (PAN)
• Campus area network (CAN)
• Global area networks (GAN)
• Virtual private network (VPN)

17. • Smallest network compared to the
other two networks.
• The simplest form of LAN is to
connect two computers together.
• LAN is operated within a limited
physical area, such as at home,
school, a single building or several
buildings.
• A network which consists of less
than 500 interconnected devices
across several buildings, is still
recognised as a LAN.
LOCAL AREA NETWORK
(LAN)
Computer Networks

18. Web access
spreadsheet
What hardware and software is
available for a small office/home
user?
Examples of LAN Usage
 Desktop usage
 Local Area
Network (Lan)
 Productivity
software
 Specialty
software
 Web usage
Computer Networks

19. METROPOLITAN AREA
NETWORK (MAN)
 A metropolitan area network (MAN) is
a network that connects two or more
local area networks or campus area
networks together but does not extend
beyond the boundaries of the
immediate town/city. MANs provide
Internet connectivity for LANs in a
metropolitan region, and connect them
to wider area networks like the
Internet
 A MAN is made from switches or
routers connected to one another with
high-speed links (usually fiber optic
cables).
 Metropolitan Area Networks (MANs)
are networks that connect LANs
together within a city.
Computer Networks

20. WIDE AREA NETWORK
(WAN)• The largest network of all network
types.
• Internet is the largest WAN in the
world.
• WAN generally covers large
distances such as states, countries
or continents.
• This is network which covers a large
geographical area, and use
communications circuits to connect
the intermediate nodes.
• In other words this is in contrast to
both the local area network and the
metropolitan area network, which
provides communication within a
restricted geographic area.
• WAN is a group of MANs or LANs or
the mixture of both networks.
Computer Networks

21. Examples of WAN Usage
What are the needs of the
large business user?
 Network
• Local area network (LAN)
• Wide Area Network (WAN)
 Large business Web site
 Sales management
 Accounting
 Desktop publishing
 Information systems
department
 Productivity software
 Scheduling
 Web access
Computer Networks

22. Comparison of LAN, MAN,
WAN
Computer Networks

23. DIFFERENCE BETWEEN
LAN MAN WAN
LAN MAN WAN
1. LAN stands for Local
Area Network.
1. MAN stands for
Metropolitan Area Network.
1. WAN stands for Wide
Area Network.
2. Used Guided Media 2. Use may be Guided or
may be Unguided media.
2. Used Unguided media.
3. A communication
network linking a number of
stations in same local area.
3. This network shares the
characteristics of packet
broadcasting networks.
3. A communication
network distinguished from
a Local Area Network.
4. LAN generally provides a
high-speed 100 Kbps to
100 Mbps.
4. A MAN is optimized for a
large geographical area
than LAN.
4. Its long distance
communications, which
may or may not be
provided by public packet
network.
Computer Networks

24. Personal area network
 A personal area network (PAN)
is a computer network used for
communication among
computer devices close to one
person. Some examples of
devices that are used in a PAN
are printers, fax machines,
telephones, and scanners. The
reach of a PAN is typically
about 20-30 feet
(approximately 6-9 meters),
but this is expected to increase
with technology
improvements.
Computer Networks

25. CAN GAN VPN NETWORKS
• A campus area network (CAN) is a
computer network made up of an
interconnection of local area networks
(LANs) within a limited geographical area. It
can be considered one form of a
metropolitan area network, specific to an
academic setting.
• A global area networks (GAN) specification
is in development by several groups, and
there is no common definition. In general,
however, a GAN is a model for supporting
mobile communications across an arbitrary
number of wireless LANs, satellite coverage
areas, etc.
• A virtual private network (VPN) is a
computer network in which some of the
links between nodes are carried by open
connections or virtual circuits in some
larger network (e.g., the Internet) instead
of by physical wires.
Computer Networks

26. NETWORKING ELEMENTS
All networks require the following
three elements:-
 1.At least two individuals who
have something to share.
 2.A method or pathway for
contacting each other.
 3.Rules so that two or more
individuals can
communicate(protocols).
Definition of Protocol:-A Protocol is a
set of rules that governs the
communications between
computers on a network. These
rules include guidelines that
regulate the characteristics of a
network such as access method,
allowed physical topologies, types
of cabling, and speed of data
transfer.
Computer Networks
Step
1
Step
2
Step
3

27. NETWORKING HARDWARE
 Networking hardware includes all
computers,peripherals,interface cards and other
equipment needed to perform data processing and
communications within the network.
 Some of the important components that are included
are:-
 File servers
 Workstations
 Network Interface
 Cards
 Switches
 Repeaters
 Bridges
 Routers
Computer Networks

28. NETWORK SERVICES
 Network services are the capabilities
that networked computers
share.Networks services are provided
by numerous combinations of
computer hardware and software.
 Computers networks are valuable
because of the services that they are
provide or manage.
 Among the many possibilities are the
following networks services.
 File services
 Print services and similar network fax
services
 Message services
 Applications services
 Database services
Computer Networks

29. NETWORK CABLES
 Network cable is medium
through which information
usually moves from one
network devices to another.
The type of cable chosen for a
network is related to the
network’s topology, protocol
and size.
 Some of the types of cables
used in networks are:-
 Unshielded Twisted
pair(UTP)Cable
 Shielded Twisted pair(STP)
 Coaxial cable
 Fiber optic cable
Computer Networks

30. Network architecture
• Overall design of a
computer network that
describes how a computer
network is configured and
what strategies are being
used.
• mainly focuses on the
functions of the networks.
• Also known as network
model or network design.
• They are two types
– Client / Server Network
– Peer-to-peer or P2P
Network
Computer Networks

31. CLIENT/SERVER NETWORK
• A client/server network
is a network in which
the shared files and
applications are stored
in the server but
network users (clients)
can still store files on
their individual PCs.
• A server is a computer
that shares information
and resources with
other computers on a
network.
• A client is a computer
which requests services
or files from a server
computer.
Computer Networks

32. Peer-to-peer or P2P
• It is a network with all the
nodes acting as both
servers and clients.
• A PC can access files
located on another PC
and can also provide files
to other PCs.
• All computers in the peer-
to-peer network has equal
responsibilities and
capabilities to use the
resources available on
the network.
• With peer-to-peer
network, no server is
needed; each computer in
the network is called a
peer.
Computer Networks

33. DifferencesComputer Networks

34. Network topology
• Computer networks may
be classified according to
the network topology
upon which the network
is based, such as bus
network, star network,
ring network, mesh
network, star-bus
network, tree or
hierarchical topology
network.
• Network topology
signifies the way in which
devices in the network
see their logical relations
Computer Networks

35. Bus Topology
 The linear bus topology connects all
the nodes to common straight
cable. All the nodes on network
share the common bus. This
topology is very reliable since a
failure of one or more nodes doesn’t
effect the Bus.
 Advantages of a Linear Bus
Topology
 Easy to connect a computer or
peripheral to a linear bus.
 Requires less cable length than a star
topology.
 Disadvantages of a Linear Bus
Topology
 Entire network shuts down if there is a
break in the main cable.
 Terminators are required at both ends
of the backbone cable.
Computer Networks

36. Star Topology
 A star topology is designed with each
node (file server, workstations, and
peripherals) connected directly to a
central network hub or switch.
 Data on a star network passes
through the hub or switch before
continuing to its destination. The hub,
switch, or concentrator manages and
controls all functions of the network.
It also acts as a repeater for the data
flow.
Advantages of a Star Topology
 Easy to install and wire.
 No disruptions to the network when
connecting or removing devices.
Disadvantages of a Star Topology
 Requires more cable length than a
linear topology.
 If the hub, switch, or concentrator
fails, nodes attached are disabled.
Computer Networks

37. Ring Topology
Ring topology
 In a ring topology all the nodes are
connected together in a loop. Data is
transmitted from node to node in a
single direction.
Advantages
 As all the data can only travel in one
direction the transmission of messages
is simple and high rates can be
achieved.
 There is no dependence or need of a
central computer or mainframe.
Disadvantages
 If on node or line fails then data cannot
continue to be transmitted between all
the rest of the nodes in the network.
 Harder to add new nodes into the
system, requires the network to be
disrupted.
Computer Networks

38. Tree Topology
 A tree topology combines
characteristics of linear bus and star
topologies. It consists of groups of
star-configured workstations connected
to a linear bus backbone cable. Tree
topologies allow for the expansion of
an existing network, and enable
schools to configure a network to meet
their needs.
Advantages of a Tree Topology
 Point-to-point wiring for individual
segments.
 Supported by several hardware and
software venders.
Disadvantages of a Tree Topology
 Overall length of each segment is
limited by the type of cabling used.
 If the backbone line breaks, the entire
segment goes down.
Computer Networks

39. MESH TOPOLOGY
 A pure mesh networks has a point to
point connections between every node in
the network. Pure mesh architectures
are not usually consider practical. One
problem is that each devices required an
interface every other device on the
network. Another problem is that amount
of cable for a large network(in terms of
no. of unit connected) is tremendous.
Advantages of Mesh topology
1) Data can be transmitted from different
devices simultaneously. This topology
can withstand high traffic.
2) Even if one of the components fails
there is always an alternative present. So
data transfer doesn’t get affected.
Disadvantages of Mesh topology
1) There are high chances of redundancy
in many of the network connections.
2) Overall cost of this network is way too
high as compared to other network
topologies.
Computer Networks

40. MESH TOPOLOGY
 A pure mesh networks has a point to
point connections between every node in
the network. Pure mesh architectures
are not usually consider practical. One
problem is that each devices required an
interface every other device on the
network. Another problem is that amount
of cable for a large network(in terms of
no. of unit connected) is tremendous.
Advantages of Mesh topology
1) Data can be transmitted from different
devices simultaneously. This topology
can withstand high traffic.
2) Even if one of the components fails
there is always an alternative present. So
data transfer doesn’t get affected.
Disadvantages of Mesh topology
1) There are high chances of redundancy
in many of the network connections.
2) Overall cost of this network is way too
high as compared to other network
topologies.
Computer Networks