The Basics and Understanding of Computer Networking.pptx

The Basics of
Computer
Networking

1.0 The Computer Network
• Arguably, the greatest advancement in
technology and communication over the
past 20 years has been the development
and advancement of the computer
network.
• From emailing a friend to on-line bill
paying to downloading data off the
Internet to e-commerce, networking has

1.1 What is a Computer Network ?
• net·work: [net-wurk] – noun, a
system containing any combination
of computers, computer terminals,
printers, audio or visual display
devices, or telephones
interconnected by
telecommunication equipment or

1.1 What is a Computer Network ? …
• A computer network is a group of two
or more interconnected computer
systems.
• You can establish a network
connection using either cable or
wireless media.
• Every network involves hardware and

• A computer network is a set of devices connected
through links.
• A node can be computer, printer, or any other
device capable of sending or receiving the data.
• The links connecting the nodes are known as
communication channels.
• Computer Network uses distributed processing in
which task is divided among several computers.
• Instead, a single computer handles an entire task,
each separate computer handles a subset.

• Computer networks share common
devices, functions, and features
including servers, clients, transmission
media, shared data, shared printers
and other hardware and software
resources, network interface
card(NIC), local operating
system(LOS), and the network

1.2 Advantages of a Computer Network
• Here are the fundamental benefits/pros of using Computer
Networking:
 Helps you to connect with multiple computers
together to send and receive information
when accessing the network.
 Helps you to share printers, scanners, and
email.
 Helps you to share information at very fast
speed

1.3 Uses of Computer Network
 Resource sharing: Resource sharing is the sharing of
resources such as programs, printers, and data
among the users on the network without the
requirement of the physical location of the resource
and user.
 Server-Client model: Computer networking is used
in the server-client model.
 A server is a central computer used to store the
information and maintained by the system
administrator.

1.3 Uses of Computer Network …
 Communication medium: Computer network behaves
as a communication medium among the users.
 For example, a company contains more than one
computer has an email system which the
employees use for daily communication.
 E-commerce: Computer network is also important in
businesses.
 We can do the business over the internet.
 For example, amazon.com is doing their business
over the internet, i.e., they are doing their business

2.0 Clients and Servers
• An important relationship on networks is that of the server and
the client.
• A server is a computer that holds content and services such as a
website, a media file, or a chat application.
• A good example of a server is the computer that holds the
website for Google’s search page: http://www.google.com.
• The server holds that page, and sends it out when requested.
• A client is a different computer, such as your laptop or cell phone,
that requests to view, download, or use the content.
• The client can connect over a network to exchange
information.
• For instance, when you request Google’s search page with

2.0 Clients and Servers …
• In the example below, two computers are
connected together with an Ethernet cable.
• These computers are able to see each other
and communicate over the cable.
• The client computer asks for a website from the
server computer.
• The website is delivered from the server, and
displayed on the client’s web browser.

2.0 Clients and Servers …
• Most requests and content delivery on networks are similar
to, or are based on, a client to server relationship.
• On a network, the server can be located almost anywhere,
and if the client has the address, it can access the content on
the server.
• Activity: What is one real world example of a client and
server relationship:
• Example:
• client: radio receiver in your car
• server: radio station
Client: _________________
Server:_________________

3.0
Components
of Computer
Network

3.0 Components of Computer Network …
Switches:
 Switches work as a controller which connects computers,
printers, and other hardware devices to a network in a
campus or a building.
 It allows devices on your network to communicate with each
other, as well as with other networks.
 It helps you to share resources and reduce the costing of
any organization.

Routers:
 Routers help you to connect with multiple networks.
 It enables you to share a single internet connection with
multiple devices and saves money.
 This networking component acts as a dispatcher, which
allows you to analyze data sent across a network.
 It automatically selects the best route for data to travel and
send it on its way.

Servers:
• Servers are computers that hold shared programs, files,
and the network operating system.
• Servers allow access to network resources to all the
users of the network.
Clients:
• Clients are computer devices which access and uses the
network as well as shares network resources.
• They are also users of the network, as they can send and
receive requests from the server.

Transmission Media / Cables and connectors:

• Transmission media is a carrier used to interconnect
computers in a network, such as coaxial cable, twisted-
pair wire, and optical fiber cable.
• It is also known as links, channels, or lines.
• Cable is a transmission media that transmits the
communication signals.
• There are three types of cables:
 Twisted pair cable: It is a high-speed cable that
transmits the data over 1Gbps or more.

 Coaxial cable: Coaxial cable resembles like a TV
installation cable.
 Coaxial cable is more expensive than twisted pair
cable, but it provides the high data transmission
speed.
 Fiber optic cable: Fiber optic cable is a high-speed cable
that transmits the data using light beams.
 It provides high data transmission speed as compared
to other cables.
 It is more expensive as compared to other cables, so it

Access points:
• Access points allow devices to connect to the
wireless network without cables.
• A wireless network allows you to bring new
devices and provides flexible support to mobile
users.
Shared Data:
• Shared data are data which is shared between

NIC(National interface card)
• NIC is a device that helps the computer to communicate with
another device.
• The network interface card contains the hardware addresses,
the data-link layer protocol use this address to identify the
system on the network so that it transfers the data to the
correct destination.
• There are two types of NIC: wireless NIC and wired NIC.
• Wireless NIC: All the modern laptops use the wireless NIC.
• In Wireless NIC, a connection is made using the antenna that
employs the radio wave technology.
•

Local Operating System:
• A local OS which helps personal computers to
access files, print to a local printer and uses
one or more disk and CD drives which are
located on the computer.
Network Operating System:
• The network operating system is a program
which runs on computers and servers.

Protocol:
• A protocol is the set of defined rules that allows two entities to
communicate across the network.
• Some standard protocols used for this purpose are IP, TCP,
UDP, FTP, etc.
Hub:
• Hub is a device that splits network connection into multiple
computers.
• It acts a distribution center so whenever a computer requests
any information from a computer or from the network it
sends the request to the hub through a cable.
•

LAN Cable:
• Local Area Network(LAN) cable is also called as
Ethernet or data cable.
• It is used for connecting a device to the
internet.
OSI:
• OSI stands for Open Systems Interconnection.
• It is a reference model which allows you to
specify standards for communications.

3.1 Unique Identifiers of Network
Hostname:
• Every device of the network is associated with
a unique device, which is called hostname.
IP Address:
• IP (Internet Protocol) address is as a unique
identifier for each device on the Internet.
• Length of the IP address is 32-bits. IPv6
address is 64 bits.

3.1 Unique Identifiers of Network…
DNS Server:
• DNS stands for Domain Name System.
• It is a server which translates URL or web
addresses into their corresponding IP addresses.
MAC Address:
• MAC (Media Access Control Address) is known as a
physical address is a unique identifier of each host
and is associated with the NIC (Network Interface
Card).
• General length of MAC address is : 12-digit/ 6

Port:

Port:
• Port is a logical channel which allows network
users to send or receive data to an application.
• Every host can have multiple applications
running.
• Each of these applications are identified using
the port number on which they are running.

3.2 Other Important Network
Components
ARP:
• ARP stands for Address Resolution Protocol,
which helps network users to convert the IP
address into its corresponding Physical
Address.
RARP:
• Reverse Address Resolution Protocol gives
an IP address of the device with given a

3.3 Uses of Computer Networks
 Helps you to share resource such as printers.
 Allows you to share expensive software's and
database among network participants.
 Provides fast and effective communication
from one computer to another computer.
 Helps you to exchange data and information
among users via a network.

3.4 Disadvantages of using Computer
Networks
o Investment for hardware and software can be costly
for initial set-up.
o If you don't take proper security precautions like
file encryption, firewalls then your data will be at
risk.
o Some components of the network design may not
last for many years, and it will become useless or
malfunction and need to be replaced.
o Requires time for constant administration.
o Frequent server failure and issues of regular cable

3.5 Features of Computer Network
• A list Of Computer network features is given below.
 Communication speed
 File sharing
 Back up and Roll back is easy
 Software and Hardware
sharing
 Security
 Scalability
 Reliability

3.5 Features of Computer Network …
Communication speed
• Network provides us to communicate over the network in a
fast and efficient manner.
• For example, we can do video conferencing, email
messaging, etc. over the internet.
• Therefore, the computer network is a great way to share
our knowledge and ideas.
File sharing
• File sharing is one of the major advantage of the computer
network.
• Computer network provides us to share the files with

Back up and Roll back is easy
• Since the files are stored in the main server which is centrally
located.
• Therefore, it is easy to take the back up from the main server.
Software and Hardware sharing
• We can install the applications on the main server, therefore, the
user can access the applications centrally.
• So, we do not need to install the software on every machine.
Similarly, hardware can also be shared.
Security
• Network allows the security by ensuring that the user has the right to
access the certain files and applications.

Scalability
• Scalability means that we can add the new components on the
network.
• Network must be scalable so that we can extend the network
by adding new devices.
• But, it decreases the speed of the connection and data of the
transmission speed also decreases, this increases the
chances of error occurring.
• This problem can be overcome by using the routing or
switching devices.
Reliability
•

4.0 Types of Computer Network
• There are various types of computer networks
available.
• We can categorize them according to their size
as well as their purpose.
• The size of a network should be expressed by
the geographic area and number of computers,
which are a part of their networks.
• It includes devices housed in a single room to
millions of devices spread.

4.0 Types of Computer Network …

4.1 Types of Computer Network : PAN
(Personal Area Network)

4.1 Types of Computer Network : PAN
(Personal Area Network)
• PAN is a computer network formed around
a person.
• It generally consists of a computer,
mobile, or personal digital assistant.
• PAN can be used for establishing
communication among these personal
devices for connecting to a digital network

4.1 Types of Computer Network : Examples of
PAN
 Body Area Network: Body Area Network moves along
with a person like a smartphone or a watch that moves
with a person.
 He can also connect with other people to interlink
the device for sharing the data.
 Offline Network: The offline network can be deployed
inside the house which is also called a home network.
 It is planned to connect with television, printers
which are not accessible to the internet.
 Small Home Office: Small Home office is used to link the
devices to cyberspace via a VPN that is a virtual private

4.1 Types of Computer Network : PAN …
Characteristics of PAN:
 It is mostly personal devices network equipped
within a limited area.
 Allows you to handle the interconnection of IT
devices at the surrounding of a single user.
 PAN includes mobile devices, tablet, and laptop.
 It can be wirelessly connected to the internet called
WPAN.
 Appliances use for PAN: cordless mice, keyboards,

4.1 Types of Computer Network : PAN …
Advantages (pros / benefits) of PAN:
 PAN networks are relatively secure and safe
 It offers only short-range solution up to ten meters
 Strictly restricted to a small area
Disadvantages (cons / drawback )of PAN
 It may establish a bad connection to other networks at the
same radio bands.
 Distance limits.

4.2 Types of Computer Network : LAN
(Local Area Network)

4.2 Types of Computer Network : LAN …
• A Local Area Network (LAN) is a group of computer and
peripheral devices which are connected in a limited area such
as school, laboratory, home, and office building.
• It is a widely useful network for sharing resources like files,
printers, games, and other application.
• The simplest type of LAN network is to connect
computers and a printer in someone's home or office.
• In general, LAN will be used as one type of transmission
medium.
• It is a network which consists of less than 5000
interconnected devices across several buildings.

Characteristics of LAN:
It is a private network, so an outside
regulatory body never controls it.
LAN operates at a relatively higher
speed compared to other WAN
systems.
There are various kinds of media

Advantages (pros / benefits) of LAN:
 Computer resources like hard-disks, DVD-ROM, and printers can share
local area networks.
 This significantly reduces the cost of hardware purchases.
 You can use the same software over the network instead of purchasing
the licensed software for each client in the network.
 Data of all network users can be stored on a single hard disk of the
server computer.
 You can easily transfer data and messages over networked computers.
 It will be easy to manage data at only one place, which makes data
more secure.
 Local Area Network offers the facility to share a single internet

Disadvantages (cons / drawback )of PAN
 LAN will indeed save cost because of shared computer
resources, but the initial cost of installing Local Area
Networks is quite high.
 The LAN admin can check personal data files of every
LAN user, so it does not offer good privacy.
 Unauthorized users can access critical data of an
organization in case LAN admin is not able to secure
centralized data repository.
 Local Area Network requires a constant LAN

4.3 Types of
Computer
Network : WAN
(Wide Area
Network)

4.3 Types of Computer Network : WAN …
• WAN (Wide Area Network) is another
important computer network that which is
spread across a large geographical area.
• WAN network system could be a
connection of a LAN which connects with
other LAN's using telephone lines and
radio waves.
• It is mostly limited to an enterprise or an

Characteristics of WAN:
The software files will be shared
among all the users; therefore, all can
access to the latest files.
Any organization can form its global
integrated network using WAN.

Advantages (pros / benefits) of WAN:
 WAN helps you to cover a larger geographical
area.
 Therefore business offices situated at
longer distances can easily communicate.
 Contains devices like mobile phones, laptop,
tablet, computers, gaming consoles, etc.
 WLAN connections work using radio
transmitters and receivers built into client

Disadvantages (cons / drawback )of WAN
 The initial setup cost of investment is very high.
 It is difficult to maintain the WAN network.
 You need skilled technicians and network
administrators.
 There are more errors and issues because of the wide
coverage and the use of different technologies.
 It requires more time to resolve issues because of the
involvement of multiple wired and wireless
technologies.

4.4 Types of Computer Network : MAN
(Metropolitan Area Network)

4.4 Types of Computer Network : MAN …
• A Metropolitan Area Network or MAN is
consisting of a computer network across an
entire city, college campus, or a small
region.
• This type of network is large than a LAN,
which is mostly limited to a single building
or site.
• Depending upon the type of configuration,

Characteristics of MAN:
It mostly covers towns and cities in a
maximum 50 km range
Mostly used medium is optical fibers,
cables
Data rates adequate for distributed
computing applications.

Advantages (pros / benefits) of MAN:
 It offers fast communication using high-speed
carriers, like fiber optic cables.
 It provides excellent support for an extensive
size network and greater access to WANs.
 The dual bus in MAN network provides support
to transmit data in both directions concurrently.
 A MAN network mostly includes some areas of a
city or an entire city.

Disadvantages (cons / drawback )of MAN
You need more cable to establish MAN
connection from one place to another.
In MAN network it is tough to make the
system secure from hackers

4.5 Other types of Computer Networks
• Apart from above mentioned here, are some other important types of
networks:
1) WLAN (Wireless Local Area Network)
2) Storage Area Network
3) System Area Network
4) Home Area Network
5) POLAN- Passive Optical LAN
6) Enterprise private network
7) Campus Area Network
8) Virtual Area Network
• Let's see all of them in detail:

4.5 Other types of Computer Networks …
1) WLAN
• WLAN (Wireless Local Area Network) helps you to link single or
multiple devices using wireless communication within a limited
area like home, school, or office building.
• It gives users an ability to move around within a local coverage
area which may be connected to the network.
• Today most modern day's WLAN systems are based on IEEE
802.11 standards.
• Functioning like a LAN, WLANs make use of wireless network
technology, such as Wi-Fi.
• Typically seen in the same types of applications as LANs, these
types of networks don’t require that devices rely on physical

2) Storage-Area Network (SAN)
• A Storage Area Network is a type of network which allows
consolidated, block-level data storage.
• It is mainly used to make storage devices, like disk arrays, optical
jukeboxes, and tape libraries.
• As a dedicated high-speed network that connects shared pools of
storage devices to several servers, these types of networks don’t
rely on a LAN or WAN.
• Instead, they move storage resources away from the network and
place them into their own high-performance network.
• SANs can be accessed in the same fashion as a drive attached to
a server.

3) System-Area Network (also known as SAN)
• System Area Network is used for a local network.
• It offers high-speed connection in server-to-server and
processor-to-processor applications.
• The computers connected on a SAN network operate as a single
system at quite high speed.
• This term is fairly new within the past two decades.
• It is used to explain a relatively local network that is designed to
provide high-speed connection in server-to-server applications
(cluster environments), storage area networks (called “SANs” as
well) and processor-to-processor applications.
• The computers connected on a SAN operate as a single system at
very high speeds.

4) Passive Optical Local Area Network (POLAN)
• POLAN is a networking technology which helps you to integrate into
structured cabling.
• It allows you to resolve the issues of supporting Ethernet protocols
and network apps.
• POLAN allows you to use optical splitter which helps you to separate an
optical signal from a single-mode optical fiber. It converts this single
signal into multiple signals.
• As an alternative to traditional switch-based Ethernet LANs, POLAN
technology can be integrated into structured cabling to overcome
concerns about supporting traditional Ethernet protocols and network
applications such as PoE (Power over Ethernet).
• A point-to-multipoint LAN architecture, POLAN uses optical splitters to
split an optical signal from one strand of single-mode optical fiber into

5) Home Area Network (HAN):
• A Home Area Network is always built using two or more
interconnected computers to form a local area network
(LAN) within the home.
• For example, in the United States, about 15 million
homes have more than one computer.
• This type of network helps computer owners to
interconnect with multiple computers.
• This network allows sharing files, programs, printers,
and other peripherals.

6) Enterprise Private Network (EPN) :
• Enterprise private network (EPN) networks are
build and owned by businesses that want to
securely connect numerous locations in order
to share various computer resources.
• These types of networks are built and owned by
businesses that want to securely connect its
various locations to share computer resources.

7) Campus Area Network (CAN):

7) Campus Area Network (CAN):
• A Campus Area Network is made up of an
interconnection of LANs within a specific geographical
area.
• For example, a university campus can be linked with a
variety of campus buildings to connect all the academic
departments.
• Larger than LANs, but smaller than metropolitan area
networks (MANs, explained below), these types of
networks are typically seen in universities, large K-12
school districts or small businesses.

8) Virtual Private Network (VPN):

8) Virtual Private Network (VPN):
• A VPN is a private network which uses a public network to connect
remote sites or users together.
• The VPN network uses "virtual" connections routed through the
internet from the enterprise's private network or a third-party VPN
service to the remote site.
• It is a free or paid service that keeps your web browsing secure and
private over public Wi-Fi hotspots.
• By extending a private network across the Internet, a VPN lets its
users send and receive data as if their devices were connected to the
private network – even if they’re not.
• Through a virtual point-to-point connection, users can access a
private network remotely.

5.0 What does Network Topology mean?
• Network topology refers to the physical or logical layout of a
network.
• It defines the way different nodes are placed and
interconnected with each other.
• Alternately, network topology may describe how the data is
transferred between these nodes.
• There are two types of network topologies: physical and
logical.
• Physical topology emphasizes the physical layout of the
connected devices and nodes, while
• the logical topology focuses on the pattern of data

5.0 What does Network Topology mean?
…
• Computers in a network have to be connected in some
logical manner.
• The layout pattern of the interconnections between
computers in a network is called network topology.
• You can think of topology as the virtual shape or structure
of the network.
• Network topology is also referred to as 'network
architecture.'
• Devices on the network are referred to as 'nodes.'
• The most common nodes are computers and peripheral
devices.

5.0 Different types of Physical Topologies
are: P2P Topology
 Bus Topology
 Ring Topology
 Star Topology
 Tree Topology
 Mesh Topology
 Hybrid Topology

5.0 Different types of Physical Topologies
are:

5.1 Point to Point (P2P) Topology

5.1 Point to Point (P2P) Topology …
• Point-to-point topology is the simplest and
easiest of all the network topologies.
• In this method, the network consists of a direct
link between two computers.
• This is faster and more reliable than other
types of connections since there is a direct
connection.
• The disadvantage is that it can only be used for
small areas where computers are in close

Advantages:
 This is faster and highly reliable than other
types of connections since there is a direct
connection.
 No need for a network operating system.
 Does not need an expensive server as
individual workstations are used to access the
files.

Disadvantages:
 The biggest drawback is that it only be used
for small areas where computers are in close
proximity.
 You can't back up files and folders centrally.
 There is no security besides the permissions.
 Users often do not require to log onto their
workstations.

5.2 BUS Topology …
• Bus topology is a network type where every device is
connected to a single cable that runs from one end of the
network to the other.
• This type of network topology is often referred to as line
topology.
• In a bus topology, data is transmitted in one direction
only.
• If the bus topology has two endpoints then it is
referred to as a linear bus topology.
• Smaller networks with this type of topology use a coaxial
or RJ45 cable to link devices together.

Advantages (pros/benefits):
 Cost of the cable is very less as compared to other
topology, so it is widely used to build small networks.
 Famous for LAN network because they are inexpensive and
easy to install.
 It is widely used when a network installation is small,
simple, or temporary.
 It is one of the passive topologies.
 So computers on the bus only listen for data being
sent, that are not responsible for moving the data from
one computer to others.

Disadvantages (cons/drawbacks):
 In case if the common cable fails, then the entire
system will crash down.
 When network traffic is heavy, it develops
collisions in the network.
 Whenever network traffic is heavy, or nodes are
too many, the performance time of the network
significantly decreases.
 Cables are always of a limited length.

5.3 RING Topology …
• In a ring network, every device has exactly two
neighboring devices for communication purpose.
• It is called a ring topology as its formation is like a ring.
• In this topology, every computer is connected to
another computer.
• Here, the last node is combined with a first one.
• This topology uses token to pass the information from
one computer to another.
• In this topology, all the messages travel through a ring
in the same direction.

 Easy to install and reconfigure.
 Adding or deleting a device in-ring topology needs
you to move only two connections.
 The troubleshooting process is difficult in a ring
topology.
 Failure of one computer can disturb the whole
network.
 Offers equal access to all the computers of the
networks

 Unidirectional traffic.
 Break in a single ring can risk the breaking of the entire
network
 Modern days high-speed LANs made this topology less
popular.
 In the ring, topology signals are circulating at all times,
which develops unwanted power consumption.
 It is very difficult to troubleshoot the ring network.
 Adding or removing the computers can disturb the

5.4 STAR Topology …
• In the star topology, all the computers connect with the
help of a hub.
• This cable is called a central node, and all other nodes
are connected using this central node.
• It is most popular on LAN networks as they are
inexpensive and easy to install.
• In star topology, each computer is connected to a central
hub using a point-to-point connection.
• The central hub can be a computer server that
manages the network, or it can be a much simpler
device that only makes the connections between

• A star topology is a topology where every node in the
network is connected to one central switch.
• Every device in the network is directly connected to the
switch and indirectly connected to every other node.
• The relationship between these elements is that the
central network hub is a server and other devices are
treated as clients.
• The central node has the responsibility of managing data
transmissions across the whole network and acts as a
repeater.
• With star topologies, computers are connected with a

 Easy to troubleshoot, set up, and modify.
 Only those nodes are affected, that has failed.
 Other nodes still work.
 Fast performance with few nodes and very low
network traffic.
 In Star topology, addition, deletion, and moving
of the devices are easy.

 If the hub or concentrator fails, attached nodes are
disabled.
 Cost of installation of star topology is costly.
 Heavy network traffic can sometimes slow the bus
considerably.
 Performance depends on the hub's capacity
 A damaged cable or lack of proper termination may
bring the network down.

5.5 TREE Topology …
• As the name suggests, a tree topology network is a
structure that is shaped like a tree with its many
branches.
• Tree topologies have a root node that is connected to
another node hierarchy.
• The hierarchy is parent-child where there is only one
mutual connection between two connected nodes.
• As a general rule, a tree topology needs to have three
levels to the hierarchy to be classified this way.
• This form of topology is used within Wide Area Networks
to sustain lots of spread-out devices.

• Tree topologies have a root node, and all
other nodes are connected which form a
hierarchy.
• So it is also known as hierarchical topology.
• This topology integrates various star
topologies together in a single bus, so it is
known as a Star Bus topology.
• Tree topology is a very common network

Failure of one node never affects the rest
of the network.
Node expansion is fast and easy.
Detection of error is an easy process
It is easy to manage and maintain

It is heavily cabled topology
If more nodes are added, then its
maintenance is difficult
If the hub or concentrator fails, attached
nodes are also disabled.

5.6 MESH Topology …
• The mesh topology has a unique network
design in which each computer on the
network connects to every other.
• It is develops a P2P (point-to-point)
connection between all the devices of the
network.
• It offers a high level of redundancy, so
even if one network cable fails, still data

5.6 MESH Topology : Types of Mesh
Topology
• Partial Mesh Topology: In this type of topology, most of the
devices are connected almost similarly as full topology.
• The only difference is that few devices are connected with
just two or three devices.

5.6 MESH Topology : Types of Mesh
Topology
• Full Mesh Topology: In this topology, every nodes or device
are directly connected with each other.

 The network can be expanded without disrupting current
users.
 Need extra capable compared with other LAN topologies.
 Complicated implementation.
 No traffic problem as nodes has dedicated links.
 It has multiple links, so if any single route is blocked, then
other routes should be used for data communication.
 P2P links make the fault identification isolation process easy.
 It helps you to avoid the chances of network failure by

 Installation is complex because every node is connected to every node.
 Dedicated links help you to eliminate the traffic problem.
 A mesh topology is robust.
 Every system has its privacy and security
 It is expensive due to the use of more cables.
 No proper utilization of systems.
 It requires more space for dedicated links.
 Because of the amount of cabling and the number of input-outputs, it is
expensive to implement.
 It requires a large space to run the cables.

5.7 HYBRID Topology …
• Hybrid topology combines two or more
topologies.
• You can see in the above architecture in such a
manner that the resulting network does not
exhibit one of the standard topologies.
• For example, as you can see in the above image
that in an office in one department, Star, Ring
and Bus topology is used.
• A hybrid topology is always produced when two

Offers the easiest method for error
detecting and troubleshooting
Highly effective and flexible networking
topology
It is scalable so you can increase your
network size

The design of hybrid topology is complex
It is one of the costliest processes

5.8 Network Topology : Summary

6.0 Work Group Computing and
Groupware
Workgroup:
• Term used to describe a
collection of computers or
other hardware connected
to a network that are all
related.
• For example, a workgroup
may be dedicated to only
the marketing department
within a company.

6.1 Work Group Computing
• A workgroup is a collection of individuals
working together on a task.
• Workgroup computing occurs when all the
individuals have computers connected to a
network that allows them to send e-mail to one
another, share data files, and schedule
meetings.
• Sophisticated workgroup systems allow users
to define workflows so that data is

6.1 Work Group Computing …
• Workgroup computing refers to any computer system that
replicates the manual work process.
• Anytime two or more people work together sharing information on
a computer system it can be defined as group computing.
• It is a way to electronically process human transactions.
• The focus is on information sharing, coordination and
collaboration.
• When two people manually send letters or memos to each other, it
is called a workgroup process.
• When two people send the same letters or memos using e-
mail, it is referred to as workgroup computing.
• Any software that supports workgroup computing can be

6.2 Levels of Work Group Computing
• Workgroup computing is about working with other
people in an electronic work environment.
• This collaboration can take place in offices located
next to each other or in different parts of the world.
• There are three different levels of group
computing:
 Individual level
 Coordinated effort


6.2 Levels of Work Group Computing …
Individual level –
• On this level the members individually work
toward a group goal but there is no group
coordination.
• Members use word processors, spreadsheets
and databases, but do not coordinate their
efforts.
• Here, we find duplication and lack of sharing of
work that oftentimes produces inconsistent

Coordinated effort –
• On this level, the members coordinate and actively manage the flow of
work by structuring work processes.
• It goes beyond individual automation and provides a structured work
environment.
• The structures are the processes that need to be completed for a legal
function.
• It focuses on the communication in the transmitting and receiving of
messages.
• The basic tool for information sharing is e-mail.
• There are no time and place barriers.
• It pushes information to others.
• Other tools that support these coordinated efforts are schedulers, project

Collaborating –
• Members here make concerted efforts for information
sharing, discussions, and obtaining other information as
needed.
• It pulls information from many different data storage
areas for use by all the team members.
• It is a “virtual” workplace that allows collaborative
information exchanges without the constraints of time
and space.
• Shared whiteboards, electronic brainstorming, shared

6.3 Types of Work Group Computing
• Teleconferencing is a meeting among people in different
geographical locations using the telephone.
• Computer teleconferencing is a keyboard conference among
several users at computers linked through a network or the
Internet.
• Document conferencing participants not only see and hear each
other, but work on text and graphic projects at the same time.
• Application sharing is allowing all the participants to run a
software program that is located on one user’s machine.
• Application viewing is similar, but only one person can edit
the documents involved but everyone can see the document.
• Videoconferencing is where two or more people are sharing video
of each other or others.

6.4 Work Group Software
• A workgroup is a collection of individuals working
together on a task.
• This could be a formal unit in an organization,
such as a department, or a temporary group
working together on a specific project.
• Specialized workgroup software makes it possible for
workgroup members to share data files, to schedule
meetings, or to define workflows where files are
automatically forwarded to the right people at each
stage of a process.

6.4 Work Group Software …
• Many personal applications extend into workgroup
applications.
• For example, if everyone in a group is using the same
online calendar to schedule their meetings, then shared
access can be set up to create a common scheduling tool.
• However, there are also applications specifically
developed for workgroups.
• Workgroup software applications are also referred to as
collaborative software or groupware.
• There are several categories of workgroup applications,
including electronic communications, electronic
conferencing, and scheduling and coordination tools.

6.4 Work Group Software …
• Increasingly, workgroup applications have become
Web-based, meaning you can access the applications
using a Web browser.
• This makes it easier to work in groups of any size in
geographically separate locations.

6.5 Electronic Communications : Email
• Electronic communication applications send messages,
documents, and files between people on different computer
systems.
• This includes tools like email, voicemail, instant messaging,
and wikis.
• Email is short for electronic mail.
• It allows for the exchange of digital messages between
one sender and one or more recipients.
• There are a few strategies to make email more effective for
workgroups.
• One approach is to set up a group in your contacts.

6.5 Electronic Communications : Email …
• If many different individuals will be sending emails to
the group, another approach is to set up an
electronic mailing list, or listserv.
• Individuals are added to this list, and messages sent
to the listserv address are sent out to all list
members.
• This is particularly useful for very large groups and
groups whose membership constantly changes.
• Many organizations have an electronic mailing list of
all their employees so that one email message can

6.5 Electronic Communications : Email …
• Voicemail makes it possible for users to receive, send,
and store spoken messages.
• Voicemail is mostly used for you to record a message if
someone is not able to answer their phone, but some
voicemail systems can be set up for you to reach a group
of people with one message.
• Voicemail can be cumbersome to work with if you have a
large number of messages, since it may not always be
immediately clear who has called and what the message
is.
• Using a voicemail-to-text service, you can have your

6.5 Electronic Communications : Chat
• Instant messaging, or IM, is a widely-used form of
online chat, which refers to text-based
communication over the Internet in real time.
• This is similar to sending text messages on your
mobile phone.
• IM uses a software application to compose, send, and
receive messages.
• This sounds like email, but the difference is that IM
occurs in real time, so your messages appear
instantaneously and you can see who is online.

6.5 Electronic Communications : Chat …
• The software application for IM typically shows up as
a small window floating on top of your other
applications.
• This makes it possible to keep an eye on your
messages while continuing with your other tasks.
• Quite a few companies have an online chat option on
their website.
• Click on the link, and you actually get to chat with a
live person.

6.5 Electronic Communications : Electronic
Conferencing
• Electronic conferencing applications consist of software that
makes it possible to have meetings in real time without being
physically in the same location.
• This includes audio conferencing, video conferencing, and
electronic meeting systems.
• Audio conferencing allows for simultaneous two-way audio
transmissions between multiple parties.
• This is also referred to as a conference call.
• Typically, one party sets up the conference call, allowing
others to call in.
• This allows any number of participants to be part of the call.
• Audio conferencing typically relies on regular telephone lines for

6.5 Electronic Communications : Electronic
Conferencing
• Video conferencing uses interactive communications
technology to enable simultaneous two-way video
and audio transmissions.
• This has also become very popular for personal use
through services such as Skype and FaceTime, but it
is also widely used by organizations.
• Video conferencing can reduce travel time and costs
and provides a more personal connection between
team members relative to other communications
means.

7.0 What is a Virtual Office and What is
telecommuting?
• Many experts say that excessive traffic
congestion on roads and surging infrastructure
costs in almost all the major business cities of
the world are forcing companies to adopt
“virtual office” models in order to telecommute
to work.

telecommuting? …
• According to Wikipedia “A virtual office is a combination of off-
site live communication and address services that allows users to
reduce traditional office costs while maintaining business
professionalism.
• Frequently the term is confused with ‘office business centers’ or
‘executive suites’ which demand a conventional lease, whereas a
true virtual office does not require that expense.”
• One problem with the Wikipedia explanation is that the author of
the Wiki is mistakenly trying to compare a virtual office Toronto
to a Toronto office business center, when the top Toronto virtual
office locations operate out of an office business center.
• Without having your virtual office run from a business center,
there is no physical address for clients or customers to send

telecommuting? …
• Let’s first look at how large companies are using Toronto virtual
office solutions.
• Companies who do not have a local Toronto office space, but
require a prestigious Toronto address for employees who work
remotely, will use a virtual office address and telephone service
to maintain a corporate presence.
• All mail is sent to the Toronto virtual office location where it can
be picked up or forwarded to private homes of the workers.
• When a client or customer phones the local exchange telephone
number, their calls are routed through the central receptionist
who handles the calls in a manner that the client has requested.
• Calls to their Toronto virtual office can re-direct to individual
employees home or cell numbers, or sent to voicemail for them to

telecommuting? …
• When smaller businesses are looking to get started, the
budget for office space is low, so most entrepreneurs choose
to run their business out of their home.
• While this may save them money, it could also be costing
them credibility and potential customers.
• Without a professional appearance that comes with having a
business address, customers may overlook dealing with them
in favor of going with a provider who has a proper business
address.
• Having a virtual office Toronto with a Toronto mail service
address at a business center demonstrates to customers that
you have a proper Toronto business address.

telecommuting? …
• Telecommuting is a work arrangement in which full
or part-time employees enjoy flexibility in working
location and hours.
• They are able to avoid the daily commute to the
office and work remotely using telecommunications
technology and access to a centralized work space.
• Many Toronto virtual office users find themselves
working from home or other locations where they are
able to get work done as well as have internet
access.

telecommuting? …
• Toronto virtual offices are often used as mini hubs for
larger companies without a local office who has
telecommuters and wants to maintain the privacy of its
workers who work out of their homes – by having a
business address that is not the home address of the
workers.
• This is especially good for companies with multiple
Telecommuting workers.
• When a group of workers needs to get together for an in-
person meeting, they can reserve a boardroom and only
pay a daily or half day price.
• This saves the company money by not having to pay

telecommuting? …
• No matter what size the company, a virtual
office Toronto can be a great solution for those
who are working from non-tradition office
spaces.
• There are plenty of other benefits available to
Toronto virtual office clients at Telsec,
including access to boardrooms, Toronto
meeting rooms, large conference rooms and
day offices.

7.1 How is a ‘Virtual Office’ different than telecommuting or co-
working?
• Access Office Business Center’s Virtual Office
packages are similar to co-working or
telecommuting but not the same.
• Although co-working, telecommuting, and virtual
offices all are ways to save on the hard costs of
leasing a space and hiring staff, a virtual office
package with Access Office Business Center
portrays your business as professional and
polished through services such as a trained
receptionist, a private phone number with

working? …
• Similar to telecommuting, virtual offices offer the ability
for you to work anywhere, anytime.
• However, as a telecommuter you have no administrative
staff or a receptionist to deal with phone calls, mail, and
meetings.
• With a virtual office, instead of connecting directly to
your personal cell phone, your calls will be answered by
an operator with a customized company greeting.
• In addition, your mail will be handled by administrative
staff and you may reserve our professionally decorated
meeting room and conference room for important

working? …
• Although co-working instead of telecommuting
adds the ability to have a specific space for
working, these organizations often strive to
maintain a casual, free-flowing vibe that may
not be appropriate for the professional attitude
you want to portray to your clients.
• With a virtual office package, you are able to
depict your business as well-established,
professional, and polished – exactly what you
need to grow your company.

7.2 Virtual Office Assistants : Advantages and Disadvantages
• Gone are the days when office meant a specific location
where people gathered to work but with modern
advancement in thinking and technology, telecommuting
or virtual office have come into vogue.
• While many vouches for traditional office settings, there is
a considerable population that believes that any means is
good enough as long as the goal is achieved.
• In the last decade or so, there has been a huge increase in
virtual offices and it has worked well both for employers as
well as employees.
• A virtual office has both advantages and disadvantages
and while it works well for some organizations, it might

7.2 Virtual Office Assistants : Advantages and Disadvantages …
S.no Advantages Disadvantages
1  It can make environment smile  A greater chance of jobs being outsourced
2  Enhanced productivity  A chance of losing out on promotions
3  Work-Life Balance  They may not be accessible that promptly
4
 Improved retention rate in the number of
employees
 The danger of being labelled as
unprofessional
5  Decrease in the number of leaves  Lack of social interaction
6  Saves office space  Security related concerns
7  A variety of candidates to choose from  Lesser productivity
8  Saves time  Less professionalism
9
 Virtual office assistants or workers are a boon for
small and upcoming firms
 Chances of miscommunication are higher
10  Relocation issues do not exist  Too much dependence on technology
11  Helps scale up the business  Being isolated
12  Cost cutting in many areas
 Many do not get the recognition and respect
they deserve
13
 A Virtual office assistant or worker means a
dedicated professional
 Not all can become virtual office assistants or
workers
14
 Efficient but physically handicapped people can be
hired
 Team work takes a backseat with virtual
office assistants or workers
15
 Virtual office assistants or workers are better at
time management
 Scheduling Conflicts

8.0 Introduction to Network Security
• Network security is the security provided to a network
from unauthorized access and risks.
• It is the duty of network administrators to adopt
preventive measures to protect their networks from
potential security threats.
• Computer networks that are involved in regular
transactions and communication within the government,
individuals, or business require security.
• The most common and simple way of protecting a
network resource is by assigning it a unique name
and a corresponding password.

8.0 Introduction to Network Security …
• Network security is a broad term that covers a
multitude of technologies, devices and processes.
• In its simplest term, it is a set of rules and
configurations designed to protect the integrity,
confidentiality and accessibility of computer
networks and data using both software and hardware
technologies.
• Every organization, regardless of size, industry or
infrastructure, requires a degree of network security
solutions in place to protect it from the ever-growing
landscape of cyber threats in the wild today.

• Today's network architecture is complex and is faced with a
threat environment that is always changing and attackers
that are always trying to find and exploit vulnerabilities.
• These vulnerabilities can exist in a broad number of
areas, including devices, data, applications, users and
locations.
• For this reason, there are many network security
management tools and applications in use today that
address individual threats and exploits and also regulatory
non-compliance.
• When just a few minutes of downtime can cause
widespread disruption and massive damage to an

• We live in an age of information.
• Businesses these days are more digitally advanced
than ever, and as technology improves, organizations’
security postures must be enhanced as well.
• Now, with many devices communicating with each
other over wired, wireless, or cellular networks,
network security is an important concept.
• Network security is the process of taking preventative
measures to protect the underlying networking
infrastructure from unauthorized access, misuse,
malfunction, modification, destruction or improper

• The Internet has undoubtedly become a huge part of our lives.
• Many people in today’s generation rely on the Internet for
many of their professional, social and personal activities.
• But are you sure your network is secure?
• There are many people who attempt to damage our Internet-
connected computers, violate our privacy and make it impossible
to the Internet services.
• Given the frequency and variety of existing attacks as well as
the threat of new and more destructive future attacks,
network security has become a central topic in the field of
cybersecurity.
• Implementing network security measures allows computers,

• Computer network security consists of measures taken by
business or some organizations to monitor and prevent
unauthorized access from the outside attackers.
• Different approaches to computer network security
management have different requirements depending on the size
of the computer network.
• For example, a home office requires basic network security
while large businesses require high maintenance to prevent
the network from malicious attacks.
• Network Administrator controls access to the data and software
on the network.
• A network administrator assigns the user ID and password to

• Information security is the process of securing
information data from unauthorized access, use,
modification, tempering, or disclosure.
• With the increased use of electronics media in our
personal lives as well as businesses, the possibility of
security breach and its major impact has increased.
• The theft of personal identity, credit card information,
and other important data using hacked user names and
passwords have become common these days.
• In addition, the theft of confidential business data may
lead to loss of business for commercial organizations.

• Network security is an organization’s strategy
that enables guaranteeing the security of its
assets including all network traffic.
• It includes both software and hardware
technologies.
• Access to the network is managed by effective
network security, which targets a wide range of
threats and then arrests them from spreading
or entering in the network.

8.1 How can we ensure network security?
• We must ensure that the passwords are Strong
and Complex everywhere- within the network
too, not just on individual computers within an
org.
• These passwords cannot be simple , default and
easily guessable ones.
• This simple step can go a long way toward
securing your networks.

8.2 Why is security so important?
• Information security performs key roles such
as:
 The organization's ability to function
without any hindrance
 Enabling the safe operation of applications
implemented on the organization's IT
systems
 Protecting the data the organization
collects and its uses

8.3 What is Network security attack?
• A network attack can be defined as any method,
process, or means used to maliciously attempt to
compromise network security.
• Network security is the process of preventing network
attacks across a given network infrastructure, but the
techniques and methods used by the attacker further
distinguish whether the attack is an active cyber attack,
a passive type attack, or some combination of the two.
• Let’s consider a simple network attack example to
understand the difference between active and passive

8.3 Network security attack : i) Active Attacks
• An active attack is a network exploit in which attacker
attempts to make changes to data on the target or data en
route to the target.

8.3 Network security attack : i) Active Attacks …
• Meet Alice and Bob.
• Alice wants to communicate to Bob but distance is a
problem.
• So, Alice sends an electronic mail to Bob via a network
which is not secure against attacks.
• There is another person, Tom, who is on the same network
as Alice and Bob.
• Now, as the data flow is open to everyone on that
network, Tom alters some portion of an authorized
message to produce an unauthorized effect.
• For example, a message meaning “Allow BOB to read
confidential file X” is modified as “Allow Smith to read

8.3 Network security attack : i) Active Attacks …
• Active network attacks are often aggressive,
blatant attacks that victims immediately
become aware of when they occur.
• Active attacks are highly malicious in nature,
often locking out users, destroying memory or
files, or forcefully gaining access to a targeted
system or network.

8.3 Network security attack : ii) Passive Attacks
• A passive attack is a network attack in which a system is monitored
and sometimes scanned for open ports and vulnerabilities, but does
not affect system resources.
• Let’s consider the example we saw earlier:

8.3 Network security attack : ii) Passive Attacks …
• Alice sends an electronic mail to Bob via a network
which is not secure against attacks.
• Tom, who is on the same network as Alice and Bob,
monitors the data transfer that is taking place
between Alice and Bob.
• Suppose, Alice sends some sensitive information like
bank account details to Bob as plain text.
• Tom can easily access the data and use the data for
malicious purposes.
• So, the purpose of the passive attack is to gain access to
the computer system or network and to collect data

8.3 Network security attack : ii) Passive Attacks …
• So, network security includes implementing
different hardware and software techniques
necessary to guard underlying network
architecture.
• With the proper network security in place, you
can detect emerging threats before they
infiltrate your network and compromise your
data.

8.4 How does network security work?
• There are many layers to consider when addressing
network security across an organization.
• Attacks can happen at any layer in the network
security layers model, so your network security
hardware, software and policies must be designed to
address each area.
• Network security typically consists of three different
controls:
a) Physical,
b) Technical and

8.4 How does network security work? …
a) Physical Network Security
• Physical security controls are designed to
prevent unauthorized personnel from gaining
physical access to network components such as
routers, cabling cupboards and so on.
• Controlled access, such as locks, biometric
authentication and other devices, is essential in
any organization.

b) Technical Network Security
• Technical security controls protect data that is
stored on the network or which is in transit across,
into or out of the network.
• Protection is twofold;
 it needs to protect data and systems from
unauthorized personnel, and
 it also needs to protect against malicious
activities from employees.

c) Administrative Network Security
• Administrative security controls consist of
security policies and processes that control user
behavior, including how users are
authenticated, their level of access and also
how IT staff members implement changes to the
infrastructure.

8.5 Types of network security
i. Network Access Control (NAC)
ii. Antivirus and Antimalware Software /
Application Security
iii.Firewall Protection
iv.Virtual Private Networks (VPNs)
v. Behavioral Analytics
vi.Wireless Security
vii.Intrusion Prevention System

8.5 Types of network security …
i) Network Access Control (NAC)
• To ensure that potential attackers cannot infiltrate your network,
comprehensive access control policies need to be in place for both
users and devices.
• Network access control (NAC) can be set at the most granular
level.
• For example, you could grant administrators full access to the
network but deny access to specific confidential folders or prevent
their personal devices from joining the network.
• To keep out potential attackers, you should be able to block
unauthorized users and devices from accessing your network.
• Users that are permitted network access should only be able to

ii) Antivirus and Antimalware Software / Application
Security
• Antivirus and antimalware software protect an
organization from a range of malicious software,
including viruses, ransomware, worms and trojans.
• The best software not only scans files upon entry to
the network but continuously scans and tracks files.
• Application security includes the hardware, software,
and processes that can be used to track and lock
down application vulnerabilities that attackers can
use to infiltrate your network.

iii) Firewall Protection
• Firewalls, as their name suggests, act as a barrier between the
untrusted external networks and your trusted internal network.
• Administrators typically configure a set of defined rules that blocks
or permits traffic onto the network.
• For example, Forcepoint's Next Generation Firewall (NGFW) offers
seamless and centrally managed control of network traffic, whether
it is physical, virtual or in the cloud.
• A firewall is a device or service that acts as a gatekeeper, deciding
what enters and exits the network.
• They use a set of defined rules to allow or block traffic.
• A firewall can be hardware, software, or both.

iv) Virtual Private Networks (VPNs)
• Virtual private networks (VPNs) create a connection to the network from
another endpoint or site.
• For example, users working from home would typically connect to the
organization's network over a VPN.
• Data between the two points is encrypted and the user would need to
authenticate to allow communication between their device and the
network.
• Forcepoint's Secure Enterprise SD-WAN allows organizations to quickly
create VPNs using drag-and-drop and to protect all locations with our
Next Generation Firewall solution.
• A virtual private network encrypts the connection from an endpoint to a
network, often over the Internet.
• This way it authenticates the communication between a device and a

v) Behavioral Analytics
• You should know what normal network behavior looks like so
that you can spot anomalies or network breaches as they
happen.
• Behavioral analytics tools automatically identify activities
that deviate from the norm.
Vi) Wireless Security
• Wireless networks are not as secure as wired ones.
• Cybercriminals are increasingly targeting mobile devices and
apps.

vii) Intrusion Prevention System
• These systems scan network traffic to identify and block attacks, often
by correlating network activity signatures with databases of known
attack techniques.
• So, these are some ways of implementing network security.
• Apart from these, you’ll need a variety of software and hardware tools
in your toolkit to ensure network security, those are:
 Firewalls
 Packet crafters
 Web scanners
 Packet sniffers
 Intrusion detection system
 Penetration testing software

8.6 Network security for businesses and consumers
• Network security should be a high priority for any
organization that works with networked data and systems.
• In addition to protecting assets and the integrity of data from
external exploits, network security can also manage network
traffic more efficiently, enhance network performance and
ensure secure data sharing between employees and data
sources.
• There are many tools, applications and utilities available that
can help you to secure your networks from attack and
unnecessary downtime.
• Forcepoint offers a suite of network security solutions that
centralize and simplify what are often complex processes and

9.0 Introduction of Firewall in Computer
Network
• Access to e-mail and other Internet resources is very
much a necessity for conducting business and
accessing information.
• However, along with the convenience that
network connectivity brings, it also raises serious
security concerns.
• With always-on connections such as cable
modems and DSL lines, Internet users need to be
increasingly vigilant of security issues, as
network traffic coming into the computer can

Network …
• In a system that is not protected with any security measures,
malicious code such as viruses can infect systems and cause
damage that may be difficult to repair.
• Unscrupulous characters on the Internet are always
snooping around trying to find open computers from
which they can steal personal files, personal information
or create other forms of mischief.
• The loss of financial records, e-mail, customer files, can
be devastating to a business or to an individual.
• In conjunction with other security measures, firewalls can
help to prevent this devastation.

Network …
• Would-be busters are capitalizing on modern technology to exploit
businesses for financial gain and espionage.
• Cyber crime is an increasingly prolific and profitable option.
• It is the single greatest risk to most companies today.
• If you’re not already aware of the scope of the threat:
• 73% of organizations do not have sufficient network security
in place (Hiscox)
• Cyber-attacks have seen a 67% increase since 2014.
• Malware is the more common attack and the most
expensive to resolve. (Accenture)
• Almost half of the cyber attacks in the US were directed at
SMBs (CNBC)

Network …
• More than 4.1 billion records were exposed in data
breaches, just through the first half of 2019 (Risk Based
Security)
• The average cost per cyber attack against an American
company in 2018 came out to more than $500,000
(Hiscox)
• The U.S. is predicted to account for more than half of
breached data by 2023 (Norton)
• The cost of cybercrime comes from business disruption,
information loss, revenue loss, and equipment damage.

9.1 What are Firewalls ?
• Firewalls are tools that can be used to enhance the security of
computers connected to a network, such as a LAN or the
Internet.
• A firewall separates a computer from the Internet, inspecting
packets of data as they arrive at either side of the firewall ?
inbound to, or outbound from, your computer ? to determine
whether it should be allowed to pass or be blocked.
• Firewalls act as guards at the computer’s entry points (which
are called ‘ports’) where the computer exchanges data with
other devices on the network.
• Firewalls ensure that packets that are requesting permission
to enter the computer meet certain rules that are established

9.1 What are Firewalls ? …
• Firewalls operate in two ways, by either
denying or accepting all messages based on a
list of designated acceptable or unacceptable
sources, or by allowing or denying all messages
based on a list of designated acceptable or
unacceptable destination ports.
• Although they sound complex, firewalls are
relatively easy to install, setup and operate.

• A firewall is a network security device, either
hardware or software-based, which monitors all
incoming and outgoing traffic and based on a
defined set of security rules it accepts, rejects
or drops that specific traffic.
 Accept : allow the traffic
 Reject : block the traffic but reply with an
“unreachable error”
 Drop : block the traffic with no reply

• A firewall establishes a barrier between secured
internal networks and outside untrusted network,
such as the Internet.

10.0 Wireless Network vs Wired Network
• Increasingly, the needs of modern homes and work
spaces are for greater and more versatile internet
coverage than just having a single PC, or group of
PCs wired up to a router with ethernet cables.
• Wireless networks enable multiple devices to use the
same internet connection remotely, as well as share
files and other resources.
• They also allow mobile devices, such as laptops,
tablets and mobile phones to move around within the
network area freely and still maintain a connection to
the internet and the network.

10.0 Wireless Network vs Wired Network …
• There are also disadvantages to wireless networks,
however, especially when you compare them with
wired networks, which generally maintain a faster
internet speed and are more secure.
• Below, I have listed all of the above points, plus the
other main advantages and disadvantages of a
wireless network vs wired network.

10.1 Wired Network
• In computing terminology, the term "wired" is used to
differentiate between wireless connections and those that
involve cables.
• A wired setup uses physical cables to transfer data between
different devices and computer systems.
• The cables can be copper wire, twisted pair or fiber optic.
• Wired network is used to carry different forms of electrical
signals from one end to the other.
• Most wired networks use Ethernet cables to transfer data
between connected PCs.
• Ethernet works or operates in a narrow range and it is little
bit difficult to configure as compared to wireless networking

10.1 Types of Wired Connections
1) Twisted pair:
• Consists of a pair of wires that are twisted
together.
• The twisting reduces noise on the wires by
cancelling out, to a certain extent, the amount of
electromagnetic interference from the
environment and between transmit and receive.

10.1 Types of Wired Connections …
2) Coaxial Cable:
• Coaxial cables consist of a cylindrical wire running down
the middle of an insulating sheath.
• Surrounding the insulating sheath is a conductive
sheath, acting simultaneously as a shield and a return
path for the signal.
• Coax cables are highly resistant to noise due to the
shielding which keeps most of the EM energy inside the
surrounding conductive sheath.

10.1 Types of Wired Connections …
3) Fiber Optic Cable:
• A fiber optic cable consists of a very long thin fiber of glass
down which light pulses can be sent.
• The data rates supported by fiber optic networks are
incredibly fast.
• So fast in fact that most people involved in fiber optic
development now say that in relation to network speeds,
computers are hopelessly slow, and so we must try to avoid
computation at all costs.

10.2 Wireless Connections
• Wireless communication involves no physical link established
between two or more devices, communicating wirelessly.
• Wireless signals are spread over in the air and are received
and interpreted by appropriate antennas.
• When an antenna is attached to electrical circuit of a
computer or wireless device, it converts the digital data into
wireless signals and spread all over within its frequency
range.
• The receptor on the other end receives these signals and
converts them back to digital data.
• A little part of electromagnetic spectrum can be used for

10.2 Types of Wireless Connections
1) RADIO TRANSMISSION
• Radio frequency is easier to generate and because of its large
wavelength it can penetrate through walls and structures
alike.
• Radio waves can have wavelength from 1 mm – 100,000 km
and have frequency ranging from 3 Hz (Extremely Low
Frequency) to 300 GHz (Extremely High Frequency).
• Radio frequencies are sub-divided into six bands.
• Radio waves at lower frequencies can travel through walls
whereas higher RF can travel in straight line and bounce
back.
• The power of low frequency waves decreases sharply as they
cover long distance.

10.2 Types of Wireless Connections …
2) MICROWAVE TRANSMISSION
• Electromagnetic waves above 100 MHz tend to
travel in a straight line and signals over them can
be sent by beaming those waves towards one
particular station.
• Because Microwaves travels in straight lines,
both sender and receiver must be aligned to be
strictly in line-of-sight.
• Microwaves can have wavelength ranging from 1
mm – 1 meter and frequency ranging from 300

3) INFRARED TRANSMISSION
• Infrared wave lies in between visible light spectrum and
microwaves.
• It has wavelength of 700-nm to 1-mm and frequency
ranges from 300-GHz to 430-THz.
• Infrared wave is used for very short range
communication purposes such as television and it’s
remote.
• Infrared travels in a straight line hence it is directional
by nature.
• Because of high frequency range, Infrared cannot cross

4) LIGHT TRANSMISSION
• Highest most electromagnetic spectrum which can be used
for data transmission is light or optical signaling.
• This is achieved by means of LASER.
• Because of frequency light uses, it tends to travel strictly
in straight line.
• Hence the sender and receiver must be in the line-of-sight.
• Because laser transmission is unidirectional, at both ends
of communication the laser and the photo-detector needs
to be installed.
• Laser beam is generally 1mm wide hence it is a work of

10.3 What is Difference b/w Wired & Wireless
Network? ...
PARAMETER WIRED WIRELESS
• Communication
Medium Copper, Fiber etc. Air
• Standard IEEE 802.3 802.11 family
• Mobility and
Roaming Limited Higher
• Security High Lower than Wired. Also easy
to hack
• Speed / Bandwidth High Speed upto 1
Gbps
Lower speed than Wired
Network
• Access to Network
Physical Access
Required Proximity Required
• Delay Low High
• Reliability High Lower than Wired
• Flexibility to
change
Less flexible to changes More flexible configuration
• Working principle
CSMA/CD, operates by
detecting the
CSMA/CA , hence reduces
possibility of collision be

10.3 What is Difference b/w Wired & Wireless
Network?
PARAMETER WIRED WIRELESS
• Interference and
Fluctuations
vulnerability
Very Less High
• Installation activity
Cumbersome and
manpower intensive Less labor intensive and easy
• Installation Time Takes longer time to
perform
Very less deployment time
• Dedicated / Shared
Connection
Dedicated Shared
• Installation Cost High Low
• Maintenance (Upgrade)
cost
High Low
• Related equipment Router, Switch , Hub Wireless Router, Access Point
• Benefits
* Greater Speed
* Higher noise immunity
* Highly reliable
* Greater Security
* No Hassles of Cable
* Best for mobile devices
* Greater mobility
* Easy installation and
management

11.0 Generations of Mobile Networks
• Much of the conversation in the mobile industry at
the moment is around the benefits of 5G and when
we can expect to see a roll-out.
• But many consumers will remember when 2G, 3G
and 4G were the latest innovation in mobile
connectivity.
• Each generation of network brought with it a
significant milestone in the development of mobile
communications, the benefits of which we’ve outlined
below.

11.0 Generations of Mobile Networks …
First Generation (1G)
• First generation mobile networks were reliant upon analog radio
systems which meant that users could only make phone calls, they
couldn’t send or receive text messages.
• The 1G network was first introduced in Japan in 1979 before it was
rolled out in other countries such as the USA in 1980.
• In order to make it work, cell towers were built around the country
which meant that signal coverage could be obtained from greater
distances.
• However, the network was unreliable and had some security issues.
• For instance, cell coverage would often drop, it would experience
interference by other radio signals and due to a lack of encryption, it
could easily be hacked.

Second Generation (2G)
• The 1G network was not perfect, but it remained
until remained until 1991 when it was replaced with
2G.
• This new mobile network ran on digital signal, not
analog, which vastly improved its security but also its
capacity.
• On 2G, users could send SMS and MMS messages
(although slowly and often without success) and
when GPRS was introduced in 1997, users could

Third Generation (3G)
• Third generation mobile networks are still in use today, but
normally when the superior 4G signal fails.
• 3G revolutionized mobile connectivity and the capabilities of
cell-phones.
• In comparison to 2G, 3G was much faster and could transmit
greater amounts of data.
• This means that users could video call, share files, surf the
internet, watch TV online and play online games on their
mobiles for the first time.
• Under 3G, cell-phones where no longer just about calling and

Fourth Generation (4G)
• The introduction of 4G went one step further than the
revolutionary 3G.
• It’s five times faster than the 3G network – and can in
theory provide speeds of up to 100Mbps.
• All mobile models released from 2013 onwards should
support this network, which can offer connectivity for
tablets and laptops as well as smartphones.
• Under 4G, users can experience better latency (less
buffering), higher voice quality, easy access to instant
messaging services and social media, quality streaming

Fifth Generation (5G)
• The 5G network is yet to be released but is widely
anticipated by the mobile industry.
• Many experts claim that the network will change not just
how we use our mobiles, but how we connect our devices to
the internet.
• The improved speed and capacity of the network will signal
new IoT trends, such as connected cars, smart cities and IoT
in the home and office.
• Mobile network operators claim that 5G will be available by
2020 but nothing is certain just yet.

11.0 Comparison of Mobile Networks
Parameters 1G 2G 3G 4G
• Image
• Name
1st Generation Mobile
Network
2nd Generation
Mobile Network
3rd Generation
Mobile Network
4th Generation
Mobile Network
• Introduced in year 1980s 1993 2001 2009
• Location of first
commercialization
USA Finland Japan South Korea
• Technology
AMPS (Advanced
Mobile Phone
System), NMT, TACS
IS-95, GSM IMT2000, WCDMA LTE, WiMAX
• Multiple
Address/Access
system
FDMA TDMA, CDMA CDMA CDMA
• Switching type Circuit switching
Circuit switching for
Voice and Packet
switching for Data
Packet switching
except for Air
Interface
Packet switching
• Speed (data rates) 2.4 Kbps to 14.4 kbps 14.4 Kbps 3.1 Mbps 100 Mbps
• Special
Characteristic
First wireless
communication
Digital version of 1G
technology
Digital broadband,
speed increments
Very high speeds, All
IP

11.0 Comparison of Mobile Networks …
Parameters 1G 2G 3G 4G
• Image
• Name 1st Generation Mobile
Network
2nd Generation Mobile
Network
3rd Generation Mobile
Network
4th Generation Mobile
Network
• Features Voice only
Multiple users on single
channel
Multimedia features,
Video Call
High Speed, real time
streaming
• Supports Voice only Voice and Data Voice and Data Voice and Data
• Internet service No Internet Narrowband Broadband Ultra Broadband
• Bandwidth Analog 25 MHz 25 MHz 100 MHz
• Operating frequencies 800 MHz
GSM: 900MHZ,
1800MHz CDMA:
800MHz
2100 MHz 850 MHz, 1800 MHz
• Band (Frequency)
type
Narrow band Narrow band Wide band Ultra Wide Band
• Carrier frequency 30 KHZ 200 KHz 5 MHz 15 MHz
• Advantage
Simpler (less complex)
network elements
Multimedia features
(SMS, MMS), Internet
access and SIM
introduced
High security,
international roaming
Speed, High speed
handoffs, MIMO
technology, Global
mobility
• Disadvantages
Limited capacity, not
secure, poor battery life,
large phone size,
background interference
Low network range, slow
data rates
High power consumption,
Low network coverage,
High cost of spectrum
licence
Hard to implement,
complicated hardware
required
Voice calls, Short
Video conferencing,
High speed applications,

The Basics and Understanding of Computer Networking.pptx

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