Lec 01 - Introduction to Computer Network.pptx

INTRODUCTION TO
COMPUTER NETWORK
ES/CIT/06 – COMPUTER NETWORKS AND APPLICATIONS

OBJECTIVES
• Identify data communication process and methods
• Identify computer network
• Understand computer network architectures
• Understand computer network types
• Identify computer network topologies
ES/CIT/006 - COMPUTER NETWORKS AND APPLICATIONS 2

DATA COMMUNICATION

WHAT IS DATA COMMUNICATION?
• Data communications (DC) is the process of using computing
and communication technologies to transfer data from one
place to another, or between participating parties.

COMPONENTS OF DATA COMMUNICATION
• Sender
• Medium
• Receiver
• Protocol
• Message

DATA COMMUNICATION TYPES
•Simplex
•Half-Duplex
•Full-Duplex

• Simplex
• It is a one way or unidirectional communication between two devices in
which one device is sender and other one is receiver.

• Half-duplex
• It is two way or bidirectional communication between two devices in
which both the devices can send and receive data or control signals in
both directions, but not at the same time

• Full-duplex
• It is two way or bidirectional communication in which both devices can
send and receive data simultaneously

DATA COMMUNICATION MEDIA

GUIDED MEDIA
• Twisted Pair Cable
• A twisted-pair consists of two copper wires twisted like a DNA helical
structure. Both the copper wires are insulated with plastic covers.
Usually, a number of such pairs are combined together and covered with
a protective outer wrapping

GUIDED MEDIA
• Co-axial Cable
• Coaxial cable is another type of data transmission medium. It is better
shielded and has more bandwidth than a twisted pair

GUIDED MEDIA
• Optical Fiber Cable
• The optical fiber cable carries data as light, which travels inside a thin
fiber of glass. Optic fiber uses refraction to direct the light through the
media.

UN-GUIDED MEDIA (WIRELESS MEDIA)
Electromagnetic wave spectrum

• Radio Wave
• Waves of frequency range 3 KHz - 1 GHz
• Omni-directional, these waves can move in all directions
• Radio waves of frequency 300KHz-30MHz can travel long distance
• Susceptible to interference
• Radio waves of frequency 3-300KHz can penetrate walls
• These waves are used in AM and FM radio, television, cordless phones

• Microwaves
• Electromagnetic waves of frequency range 1GHz - 300GHz.
• Unidirectional, can move in only one direction.
• Cannot penetrate solid objects such as walls, hills or mountains.
• Needs line-of-sight propagation i.e. both communicating antenna must
be in the direction of each other.
• Used in point-to-point communication or unicast communication such
as radar and satellite.
• Provide very large information-carrying capacity.

• Infrared Waves
• Electromagnetic waves of frequency range 300GHz - 400THz.
• Very high frequency waves.
• Cannot penetrate solid objects such as walls.
• Used for short-distance point-to-point communication such as mobile
to-mobile, mobile-to-printer, remote-control-to-TV, and Bluetooth
enabled devices to other devices like mouse, keyboards etc

WIRELESS TECHNOLOGIES
• Wi-Fi
• Bluetooth
• Mobile Network Technologies (2G/3G/4G/LTE)
• Global Position System (GPS)

COMPUTER NETWORK

WHAT IS A COMPUTER NETWORK?
• A computer network is a system that connects two or more
computer devices through data communication media to
transmit and share information or resources.

KEY COMPONENTS OF COMPUTER
NETWORK
•Network Devices
•Links
•Communication Protocols
•Network Defense

NETWORK
• Network Devices
• Network devices or nodes are computing devices that need to be linked
in the network.
• Computers
• Servers
• Switches
• Routers

NETWORK
• Links
• Links are the transmission media which can be of two types
• Wired media (Guided Media)
• Wireless Media (Un-guided Media)
• Communication Protocols
• A communication protocol is a set of rules followed by all nodes involved in
the information transfer. Some common protocols include the internet
protocol suite (TCP/IP), IEEE 802, Ethernet, wireless LAN, and cellular
standards. TCP/IP is a conceptual model that standardizes communication in
a modern network.

NETWORK
• Network Defense (Network Security)
• While nodes, links, and protocols form the foundation of a network, a
modern network cannot exist without its defenses. Security is critical
when unprecedented amounts of data are generated, moved, and
processed across networks.
• Ex: Firewall, Intrusion Prevention System (IPS), Intrusion Detection System
(IDS), Network Access Control (NAC), Content Filters, Proxy Servers, Load
Balancers

WHY COMPUTER NETWORKING?
• Sharing Information

• Sharing hardware and software

• Centralized administration and support
• Internet Banking
• E-commerce
• Fuel Pass

ADVANTAGES OF COMPUTER NETWORK
Accessing databases, transferring, processing and retrieval of data can be done on-
line
Online credit card checking, e-commerce and Electronic Fund Transfer are possible.
Easily administered
Provides an efficient means of communication such as e-mail, Voice mail and
Video conferencing.
 Tasks of distributed nature can be processed by distributed computer systems by
exchanging data.
Provides a way to share data, programs, peripherals, computing power and
information.
Provides data security (Comparing to other communication devices)

NETWORK CONNECTION TYPES
• There are different types of communication connections in
existence between two endpoints.
• Point-to-point Connection
• A point-to-point connection is a direct link between two devices such as a
computer and a printer.
• It uses dedicated link between the devices.
• The entire capacity of the link is used for the transmission between those
two devices.

NETWORK CONNECTION TYPES
• Multi-point Connection
• A multipoint connection is a link between three or more devices.
• It is also known as Multi-drop configuration.

COMPUTER NETWORK ARCHITECTURE
• Computer Network Architecture is defined as the physical and logical design
of the software, hardware, protocols, and media of the transmission of
data. Simply we can say that how computers are organized and how
tasks are allocated to the computer.
• The two types of network architectures are used:
• Peer-To-Peer network architecture
• Client/Server network architecture

PEER-TO-PEER ARCHITECTURE
• The peers referred to here are the individual devices
linked together directly, having equal responsibilities
and equal powers without the presence of any central
authority.
• Due to the absence of a central device in charge of
tasks, this architecture is also known as
decentralized architecture.
• Each computer has special rights for resource
sharing, however this might cause issues if the
computer with the resource is unavailable.
• Useful in smaller environments with less number of
computers.

PEER-TO-PEER ARCHITECTURE
• Advantages of peer-to-peer architecture
• No particular device is a client or a server, the tasks and responsibilities of
servers are distributed among all the devices, which also act as clients.
• Very inexpensive to set up, as there is no requirement of a centralized
server, and this also ensures that in case of any failure in the network, all
unaffected devices continue to operate normally.
• It’s simple to set up and maintain because each computer runs
independently.
• Disadvantages of peer-to-peer architecture
• No centralized system, thus difficult to keep a backup of the data in case of
any fault.
• It has a security flaw because the computers are self-managed.
• With a growth in the number of machines on this network, performance,
security, and access may all become big issues.

CLIENT / SERVER NETWORK ARCHITECTURE
• This is also known as centralized architecture, as one
powerful central computer is in charge of serving all the
requests from the client computers. This central
computer is a server.
• The client computers connect to the server as and when
they require the use of shared resources or shared data.
All of the shared data is stored solely in the server, and
not on any other computer.
• A server handles all of the key tasks, such as security
and network administration.
• All of the clients interact with one another via a server.

• Advantages of client / server architecture
• This type of architecture is much easier to scale since it is much more
convenient to add more server computers than configure the network on
each and every computer (as is the case in peer-to-peer architecture).
• Much faster network speeds.
• Because a single server manages the shared resources in a Client/Server
network, there is improvement in security.
• Backing up data is easy because of the centralized system.
• The server provides a customized Network Operating System (NOS) to
offer resources to a large number of users that want them.

• Disadvantages of client / server architecture
• More prone to downtime because if the server fails, none of the client
machines are able to get their requests served.
• Requirement of a dedicated network administrator to handle all of the
resources.
• It is far more expensive than P2P. This is due to the requirement for a
server with more RAM, as well as the necessity for several networking
devices such as hubs, routers, switches, and so on.

NETWORK TYPES
• Local Area Network (LAN)
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)

LOCAL AREA 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.
• 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.

METROPOLITAN AREA 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,
this type of network allows you to cover an
area from several miles to tens of miles.

WIDE AREA NETWORK (WAN)
• It is called a wide-area network
because it spans beyond a single
building or large campus to
include multiple locations spread
across a specific geographic area,
or even the world.

NETWORK TOPOLOGY
• Topology defines the structure of the network of how all the
components are interconnected to each other.
• Star Topology
• Bus Topology
• Ring Topology
• Tree Topology
• Mesh Topology

STAR TOPOLOGY
• Star topology is an arrangement of the network in
which every node is connected to the central hub,
switch or a central computer.
• The central computer is known as a server, and
the peripheral devices attached to the server are
known as clients.
• Coaxial cable or RJ-45 cables are used to connect
the computers.
• Hubs or Switches are mainly used as connection
devices in a physical star topology.
• Star topology is the most popular topology in
network implementation.

ADVANTAGES OF STAR TOPOLOGY
• Efficient troubleshooting
• Easy to control
• Limited failure
• Easily expandable
• Cost effective
• High data speeds

DISADVANTAGES OF STAR TOPOLOGY
• If the central hub or switch goes down, then all the connected
nodes will not be able to communicate with each other
• Sometimes cable routing becomes difficult when a significant
amount of routing is required.

BUS TOPOLOGY (LINE TOPOLOGY)
• Bus topology is a network setup where each computer and
network device is connected to a single cable or backbone.
• Depending on the type of computer network card, a coaxial
cable or an RJ-45 (Twisted-pair cable) network cable is used to
connect them together

ADVANTAGES OF BUS TOPOLOGY
• It is the easiest network topology for connecting peripherals or computers in
a linear fashion.
• It works very efficiently well when there is a small network.
• The length of cable required is less than a star topology.
• It is easy to connect or remove devices in this network without affecting any
other device.
• Very cost-effective as compared to other network topology
• It is easy to understand topology.
• Easy to expand by joining the two cables together.

DISADVANTAGES OF BUS TOPOLOGY
• Bus topology is not great for large networks.
• Identification of problems becomes difficult if the whole network goes
down.
• Troubleshooting individual device issues is very hard.
• Need terminators are required at both ends of the main cable.
• Additional devices slow the network down.
• If the main cable is damaged, the whole network fails or splits into two.
• Packet loss is high.
• This network topology is very slow as compared to other topologies.

RING TOPOLOGY
• A ring topology is a network
configuration where device
connections create a circular data
path. Each networked device is
connected to two others, like points
on a circle. Together, devices in a
ring topology are called a ring
network.
• In a ring network, packets of data
travel from one device to the next
until they reach their destination.

ADVANTAGES OF RING TOPOLOGY
• All data flows in one direction, reducing the chance of packet
collisions.
• A network server is not needed to control network connectivity
between each workstation.
• Data can transfer between workstations at high speeds.
• Additional workstations can be added without impacting
performance of the network.

DISADVANTAGES OF RING TOPOLOGY
• All data being transferred over the network must pass through
each workstation on the network, which can make it slower
than a star topology.
• The entire network will be impacted if one workstation shuts
down.
• The hardware needed to connect each workstation to the
network is more expensive than Ethernet cards and
hubs/switches.

TREE TOPOLOGY
• Tree topology is also known as a
star bus topology. It incorporates
elements of both a bus topology and
a star topology.
• If the main cable (trunk) between the
two star topology networks failed,
those networks would be unable to
communicate with each other.

ADVANTAGES OF TREE TOPOLOGY
• As the leaf nodes can add one or more nodes in the hierarchical chain, this topology
provides high scalability.
• The other nodes in a network are not affected if one of their nodes gets damaged or does
not work.
• Tree topology provides easy maintenance and easy fault identification can be done.
• A callable topology. Leaf nodes can hold more nodes.
• Supported by several hardware and software vendors.
• Point-to-point wiring for individual segments.
• Tree Topology is highly secure.
• It is used in WAN.
• Tree Topology is reliable.

DISADVANTAGES OF TREE TOPOLOGY
• This network is very difficult to configure as compared to the
other network topologies
• The establishment cost increases as well.
• Due to the presence of a large number of nodes, the network
performance of tree topology becomes a bit slow.
• Requires a large number of cables compared to star and ring
topology.

MESH TOPOLOGY
• Mesh topology is a type of
network topology in which all
devices in the network are
interconnected. In a mesh
topology, data can be
transmitted by routing (sent the
shortest distance) and flooding
(sent to all devices).

ADVANTAGES OF MESH TOPOLOGY
• Multiple devices can transmit data at the same time, allowing
for high amounts of traffic
• If one device fails, data transmission is not impacted in the rest
of the network
• Adding devices to the network does not disrupt data
transmission
• Troubleshooting is easier than with alternative topologies

DISADVANTAGES OF MESH TOPOLOGY
• Network installation and maintenance is time and resource
intensive
• High power requirement due to all the devices needing to
remain active all the time
• Requires a large amount of cables and ports
• The potential for a large amount of redundant connections
increases costs and reduces efficiency

Q & A

THANK YOU!

Lec 01 - Introduction to Computer Network.pptx

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