Networking: A Beginner's Guide

BY
YASHWANT IMBA/40534/11
PRASOON KUMAR IMBA/40535/11
AMIT KESARWANI IMBA/40547/11
AKASH MISHRA IMBA/40550/11
SHUBHAM IMBA/40551/11
ASHISH KR. SINHA IMBA/40555/11

NETWORKING
DATA COMMUNICATION:
CONCEPTS
COMPONENTS
DATA MEASUREMENT
TRANSMISSION MODE
TRANSMISSION MEDIA
TRANSMISSION
METHODS
MODULATION
TECHNIQUES
COMPUTER NETWORK
TYPES: LANs & WANs
INTRANET & EXTRANET
TOPOLOGIES
PROTOCOL & THE OSI
MODEL
NETWORK DEVICES

What is Data Communication?
DATA COMMUNICATION: CONCEPTS
Data communication is the exchange of data between 2 devices via
some form of wired or wireless transmission medium.
It includes the transfer of data, methods of transfer, and the
preservation of data during the transfer process.
The hardware and software, that facilitate data communication,
taken together forms a communication system.
To initiate data communication, the communicating devices should be
a part of an existing communication system.
For effective data communication, the following 3 fundamental
characteristics should be considered:-
1) Delivery
2) Accuracy
3) Timeliness

PROTOCPL PROTOCPL
Step-1
Step-2
…..
…..
…..
Step-7
Data communication
components:-
5 basic components in data
communication system
are:
1. Message
2. Sender
3. Receiver
4. Medium
5. Protocol
Step-1
Step-2
…..
…..
…..
Step-7
MESSAGE
SENDER
TRANSMISSION
MEDIUM RECEIVER

Measurement of Data :-
 The rate of data transmission is measured in Bandwidth.
 Bandwidth refers to the maximum volume of information
that can be transferred over any communication medium.
 The more the information needed to transmit in a given
period, the more the bandwidth required.
 On digital circuits, bandwidth is measured in bits per
second (bps). 1,000 bps = 1 Kbps.
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The level of Bandwidths falls into 3 categories:
1) Narrow Band
 There is a single transmission channel of 64Kbps or less.
 There can be a number of 64Kbps transmission (N*64Kbps)
but not more than 1.544Mbps (also called T1 line).
2) Wide Band
 Bandwidth capacity lies between 1.544Mbps – 45Mbps.
3) Broad Band
 The bandwidth capacity is equal to 45Mbps or a T3 line.
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Measurement of Data :-

Data Transmission Mode :-
Data transmission mode refers to the direction
of signal flow between 2 linked devices. There
are 3 types of transmission modes:
Simplex
Half -
Duplex
Full –
Duplex

SIMPLEX
DIRECTION OF DATA
 Simplex transmission is unidirectional, i.e., the
information flows in one direction across the circuit,
with no capability to support response in the other
direction.
 Only one of the communicating devices transmits
information, the other can only receive it. E.g.- TV
communication.

HALF- DUPLEX
DIRECTION OF DATA AT T1
DIRECTION OF DATA AT T2
 In Half-Duplex mode, each communicating device
can receive and transmit information, but not at the
same time.
When one device is sending, the other can only
receive at that point of time. E.g. – wireless handsets
(generally used by military personnel).

FULL- DUPLEX
DIRECTION OF DATA AT ALL TIME
 It is also known as simply the Duplex mode. It allows
both communicating devices to transmit and receive
data simultaneously.
E.g. – Telephone network.

Transmission Media refers to
the physical media through
which signals are transmitted.
It can be wired or wireless.
The signal transmitted from
one device to another is
through Electromagnetic
waves.
An electromagnetic signal is
the combination of electric and
magnetic fields, vibrating in
conjugation with each other.
EM signals include power,
voice, radio waves, infrared
light, visible light, UV light, X-rays,
Gamma-rays. All these
together constitute an EM
spectrum.
These signals can travel
through vacuum, air or any
other transmission medium.
Media
Guided
Media
Open Wire
Twisted
Pair
UTP Cable
STP Cable
Coaxial
Wire
Optical
Fiber
Unguided
Media
E.g.-Radio
Frequency
Propagation
Ground
Wave
Ionospheric
Propagation
Line of Sight
E.g.-FM
Radio
E.g.-
Microwave
E.g.-
Satellite
Data
Transmission
Media

Guided Media (Bound Media) – Wired Media
Guided Transmission Media use a cabling system that guide the data signals along
a specified path through the cables. Hence they are also called bound media. 4
basic types are- Open Wire, Coaxial Wire, Twisted Pair, and Optical Fiber.
Type 1- Open Wire
Open wire is used to
transmit power through
wires strung along
power poles.
Not recommended for
long data transmission.
The reasons are:-
1. Loss of energy
problem.
2. It can easily be tapped.
3. No shielding from
noise interference.
Type 2- Coaxial Wire
Coaxial cables have a single
central conductor, which is
made up of solid wire
(usually Cu).
Features:-
1. It is very robust and is
used in Cable TV network.
2. It offers a bandwidth of
10Mbps.

Type 3- Twisted Pair
Pairs of wires are twisted together which are surrounded by an insulating material and an
outer layer called jacket. They are twisted to reduce noise.
Each pair consist of wire, for receiving data signal, and a wire for transmitting data signal.
Like open wire, these also transmit data in the form of current.
Twisted pairs are used in a short distance communication (less than 100m) and they are
available in 2 forms:- unshielded twisted pair (UTP) & shielded twisted pair (STP) cables.
UTP:-
STP:-
It is the most common
STP cable has a metal foil
type of telecommunication
that covers each pair of
medium in use today.
insulated conductors.
It is most suited for both
data & voice transmission
The metal foil prevents
and hence commonly used
infiltration of EM noise.
in telephone systems.
The shield also helps to
They have a transmission
eliminate crosstalk.
speed of up to 9600bps.

Type 4- Optical Fiber
Optical fiber consists of thin glass fibers that
can carry information in the form of visible light,
unlike coaxial wire & twisted pair which carry
signal as electrical current.
The main components of an optical fiber are:
Core- it is a very narrow stand of glass.
Cladding- it is a concentric layer of glass around the
core.
Jacket- it is a protective coating of plastic which
covers the cladding.
Optical fiber works on the principle that the
core refracts the light and the cladding reflects the
light; the core refracts the light and guides the
light along its path. Whereas the cladding reflects
any light back into the core and stops it from
escaping through the medium. This principle is
called TOTAL INTERNAL REFLECTION.
The light pulses, which can be carried over long
distances via optical fiber cable, carry information.

Type 4- Optical Fiber
Advantages of optical fiber:-
1. Since transmission is light-based rather
than electricity, it is immune to noise
interference.
2. Transmission distance is greater than
other guided media because of les
signal attenuation (degradation of
quality over distance).
3. It is more secure because cable can not
be tapped.
4. They are smaller and lighter than
Copper wire and are free from
corrosion as well.
5. Fiber optic offers, by far, the greatest
bandwidth of any transmission system
Disadvantages of optical fiber:-
1. Fiber optic is expensive as it is costly to
produce, maintain, and install.
2. They are more fragile as fiber optic
tends to break easily as compared to
Copper wire.

Unguided Media – Wireless Media
Unguided Transmission Media is data signals that flow through the air.
They are not bound to a fixed channel to flow.
One of the most common unguided media of transmission is- radio frequency
propagation.
Radio frequency propagation: In RF propagation, the signal is carried over
carrier Type waves 1-Open (waves Wire
which carry signals over them), which have frequencies in the
range of radio frequency spectrum.
There are 3 types of RF propagation:
1. Ground wave propagation
2. Ionospheric propagation
3. Line of sight propagation
1. Ground wave propagation:
 It follows the curvature of the
earth
 They have carrier frequencies of
up to 2MHz
 E.g.- AM Radio
Type 2- Coaxial Wire
2. Ionospheric propagation:
 The signal waves bounces off the
earth’s ionosphere layer
 Frequency range is 30-85MHz

3. Line of Sight Propagation-
 It transmits exactly in the line of sight .
 The receiving station must be in the view of transmitting
station.
 Typically the line of sight due to the earth’s curvature is
50km to the horizon
 E.g.- FM Radio, Microwave, & Satellite.
Microwave:
•Microwave transmission is line of sight
transmission.
•The transmit station must be in visible
contact with the receiving station.
•Since the line of sight due to earth’s
curvature is only 50 km to the horizon,
repeater stations must be placed so the
data signal can travel farther than the
distance limit.
Satellite:
•Satellites are set in geostationary orbits which are
placed 36,000 km above the earth’s surface, and
rotates in synchronization to earth.
•The communication is carried through uplinks and
downlinks. The uplink transmits the data to the
satellite and downlink receives the data from the
satellite.
•Uplinks and downlinks are also called earth’s
stations because they are located on earth.
•The area shadowed by the satellite in which the data
can be transferred is called the footprint.

Data Transmission Methods :-
 Any information to be transmitted from one communicating device to
another, by any media (wired or wireless), is first transformed into
electromagnetic signals. Information is transmitted by 2 methods:
ANALOG & DIGITAL.
 Analog signals:
An analog signal is a continuous waveform
that changes smoothly over time.
Most fundamental form of an analog signal
is- the Sine Wave.
Sine waves have 3 main characteristics:
amplitude, frequency, & wavelength.
 Digital Signals:
Digital data is the data stored in the
form of 0 and 1. When a signal is at high
point, its value is 1 and when it is low, its
value is 0.
For data to be processed by computer
or any digital device, they are converted
into digital (machine readable) formats.
1 1 1
0 0
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e Digital Signal Wave

Modulation Techniques
Before an information is transmitted in a wide communication system, the information
or modulating signals are superimposed on a carrier signal, which propagates by means
of an electromagnetic wave. This process is called modulation.
The carrier waves carry the signals to travel over ling distances.
Generally, there are 2 forms of modulation- amplitude & frequency.
Amplitude Modulation:
DATA COMMUNICATION:
In this modulation, the frequency
of the carrier remains the same,
only the amplitude changes to
follow variation in the signal.
CONCEPTS
Frequency Modulation:
In this modulation, the amplitude of
the carrier remains the same. The
frequency change to follow
variation in the signal.

COMPUTER NETWORK
What is a Computer Network ?
A computer network is simply two or more computers
connected together to share information and
resources.
The network connection can be through some wired
media such as telephone lines, coaxial cables, or
through wireless media such as satellite links, radio,
an/or some other communication technique.
The purpose of connection is to share information an
resources.

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TYPES OF NETWORKS
Broadly there are two types of network on the basis of various factors like the size of
the network, the distance it covers, and the type of link used in the interconnection:
LAN- Local Area Network
WAN- Wide Area Network
LAN:
A LAN is a computer network that spans
only a small geographical area, such as
an office, home or building.
Of the many computers connected, one
computer is designated as the file server,
which stores all the software that controls
the network along with the software that
can be shared by the computers attached
to the network. Other computers
connected to the file server are called
workstations.
Most LANs use cable – connectivity.
Bandwidth- 10 to 100 Mbps.
The cost of setting a LAN is low.
WAN:
It is a connection of multiple LANs
which are geographically separate.
They span over a large geographical
area such as cities, states, countries or
even the whole world.
MANs use long-range
communication technologies such as
telephone lines, satellite links, etc.
Transmission speed is much higher as
compared to LAN.
Cost of setting up a WAN is very high.
There are several types of WAN:
Metropolitan area network(MAN)
Public Access Network(PAN)
Value Added Network(VAN)
Virtual Private Network(VPN)
INTERNET (largest WAN in existence)

INTRANET TYPES OF
NETWORKS
INTRANET & EXTRANET
EXTRANET
 Intranet – An intranet is a private LAN designed for use by
everyone within an organization. An intranet might consist of an
internal e-mail system, a message board and one or more Web
site portals that contain company news, forms, and personnel
information.
Access to an intranet’s web site is restricted by a firewall.
 Extranet – a network that connects people within your
company with people who are outside your company--all within
a secure, password-protected network that can be accessed
from anywhere.
C O M P U T E R N E T W O R K

EXAMPLE OF FIREWALL
 Firewalls are systems that establish access control policies
among networks.
 They can block information from entering a network or from
getting out of that network, they can permit different users to
perform different kinds of operations, according to the user's
authorizations.
C O M P U T E R N E T W O R K

BENEFITS OF A NETWORK
Information sharing: Authorized users can use other
computers on the network to access and share information and
data. This could include special group projects, databases, etc.
Hardware sharing: One device connected to a network,
such as a printer or scanner, can be shared by many users.
Software sharing: Instead of purchasing and installing a
software program on each computer, it can be installed on the
server. All of the users can then access the program from a single
location.
Collaborative environment: Users can work
together on group projects by combining the power and
capabilities of diverse equipment.

RISKS OF NETWORK COMPUTING
The security of a computer network is challenged
everyday by:
• Equipment malfunctions
• System failures
Note: equipment malfunctions and system failures
may be caused by natural disasters such as floods,
storms, or fires, and electrical disturbances
• Computer hackers
• Virus attacks

Network Topologies
The term topology refers to the way a network is laid out, either
physically or logically.
It can be considered as the network’s shape.
It is the geometric representation of the relationship of all the
links.
There are 5 basic topologies-
Bus
Ring
Star
Tree
Mesh
COMPUTER NETWORK

•Connecting to a
computer or peripheral to
a linear bus is easy.
•It requires least amount
of cabling, and hence is
les expensive.
•Entire network shuts
down if there is a failure
in the common bus or
backbone (single cable).
•Heavy traffic can slow
down a bus.
Bus Topology
All stations are connected to a single long cable.
Any station can send a signal along the cable,
which all other stations will receive. Unlike ring
topologies, the cable doesn't close a loop.

•It is easy to install and
reconfigure.
•Every computer is given
equal access to the ring.
Hence, no single computer
can monopolise the
network.
•Failure in any cable or
node breaks the loop and
can take down the entire
network.
•Maximum ring length and
number of nodes are
limited.
RING Topology
In ring topology, computers are connected in a
cable-loop.
All messages travel through a ring in the same
direction (clockwise or counterclockwise) until it
reaches its destination.

•It is easy to install and wire.
•The network is not disrupted
even if a node fails or is
removed from the network.
•Fault detection and removal
of faulty parts is easier.
•It requires a longer length of
cable.
•If the hub fails, nodes
attached to it are disabled.
•The hub is costly, making the
network expensive as
compared to bus and ring
topology.
STAR Topology
File Server
Computers and devices are connected via a
centralised network component called HUB, which
acts as a central controller.
It uses mostly twisted pair cables. Other cables
are also used.

tree Topology It is a combination of linear bus and
•The signal transmission distance
increases as the signal passes through a
chain of hubs.
•It allows for easy expansion of an
existing network.
star topologies.
It consists of groups of star-configured
workstations connected
to a bus backbone cable .
Not every node plugs directly to
the central hub. The majority of
nodes connect to a secondary hub
that in turn is connected to the
central hub.
Each secondary hub in this
topology functions as the
originating point of a branch to
which other nodes connect.
•If the backbone line breaks, the
entire segment goes down.
•It is more difficult to configure
and wire than other topologies.
Secondary Hub

•The use of large number of
links eliminates network
congestion.
•If one link becomes unstable,
it does not disable the entire
system.
•The amount of required cabling
is very large.
•As every node is connected to
the other, installation and
reconfiguration is very difficult
•The amount of hardware
required can make this topology
expensive.
MESH Topology
Every node has a point-to-point link to every other
node.
Messages sent on a mesh network can take any of
several possible paths from source to destination.

NETWORK / COMMUNICATION PROTOCOLS
A computer protocol is simply a set of rules and procedures for
transmitting data between two or more devices. They define the
manner in which the data communication takes place.
If one computer is sending information to another and they both
follow the same protocol, the message gets through; regardless of what
type of machines they are and on what operating system they are
running.
As long as the machines have software that can manage the protocol,
communication is possible.
• Features determined by the protocol are-
– How the sending device indicates it has finished sending the
message.
– How the receiving device indicates it has received the message.
– The type of error checking to be used.

The OSI Model NETWORK/COMMUNICATION PROTOCOLS
Open Systems Interconnection (OSI) is a basic reference model for
communication between 2 end users in a network.
The model lays a framework for the design of network systems that
allow for communication across all types of computer systems.
OSI model is a structure that applies (fully or in parts) for any digital
communication network.
It is a prescription of characterizing and standardizing the functions of
a communication system in terms of abstraction layers.
It consists of separate but related 7 Layers that represent a functional
division of the tasks needed to implement a network. They are- Physical,
Data Link, Network, Transport, Session, Presentation, Application . Each
layer consists of a set of specific protocols.
Similar communication functions are grouped into logical layers. A
layer serves the layer above it and is served by the layer below it.
For example- the 4th layer, which provides error-free
communications across a network, avails the path needed by
applications of 5th layer, while it instructs the 3rd layer to send and
receive packets that make up the contents of that path.

Categories of the OSI layer:
NETWORK/COMMUNICATION
The OSI Model PROTOCOLS
These layers deal with application
issues, and are implemented only
in the software.
The highest layer- Application, is
closest to the end user.

These layers handle the data
transport issues.

The Physical and Data-Link layer
are implemented in both hardware
and software.

Network & Transport layers are
implemented only in software.

The lowest layer- Physical layer is
closest to the cabling and places the
information on the cables.

Layer Breakdown
 Layer 1: Physical
– The physical network hardware, medium.
 Layer 2: Data Link
– How data is organized into frames, and how to
transmit those frames. Byte/bit stuffing, checksums.
 Layer 3: Network
– How addresses are assigned, and how packets are
transmitted from one end of the network to the
other.

Layer Breakdown (cont.)
 Layer 4: Transport
– How to reliably transfer data.
 Layer 5: Session
– How to start sessions (connections) with remote devices,
machines. (Sockets)
 Layer 6: Presentation
– How to represent data. Does int, char replacements.
 Layer 7: Application
– How one user-level program requests a connection to another
machine, and how the machine responds.

NETWORK
INTERFACE
CARD (NIC)
NETWORK
DEVICES
HUB
REPEATER
BRIDGE
SWITCH
MODEM
ROUTER
GATEWAY
THE NETWORK
DEVICES
INTERCONNECT
INDIVIDUAL
COMPUTERS
AND ENSURE
THAT THEY
COMMUNICATE
EFFICIENTLY
COMPUTER NETWORK

NETWORK
INTERFACE
CARD (NIC)
•NIC is the first contact between the machine and the
network. It connects clients, servers and peripherals to
the network via a port.
•They are small circuit boards that can be inserted onto
one of the computer motherboard’s slot.

HUB
(connectors)
•A HUB is a small box that connects individual devices on a
network so that they can communicate with one another.
•The hub's major function is to replicate data it receives from
one device attached to it to all others.
•It is also called CONNECTOR, it works on the physical layer
of the OSI model.

REPEATER
•A repeater is an electronic device that that operates on
the physical layer of the OSI model.
•Signals that carry information within a network can
travel a fixed distance before attenuation weakens them
enough to be disintegrated. A repeater installed on the
link receives the signal, regenerates it, and sends the
refreshed copy back to the link.

SWITCH
•Like a hub, a switch too connects individual devices on
a network so that they can communicate with one
another.
•Switches work on the data link layer of the OSI model.
•They are ‘intelligent’ HUBS. Unlike hubs, network
switches can inspect the data packet as they are
received, determine the source and the destination
device, and forward the packet appropriately.

BRIDGE
BRIDGE
•A bridge filters data traffic at a network boundary.
•It reduces the amount of traffic on a LAN by dividing it
into segments.
•It inspects incoming traffic and decides whether to
forward or discard it.
•Bridges operate at the data link layer of the OSI model.

ROUTER
Router/firewall
•Routers connect two or more networks and forward data
packets between them.
•A router creates and/or maintains a table, called a ‘routing
table’ that stores the best routes to certain network
destinations.
•Router’s sole aim is to trace the best route for information to
travel.

GATEWAY
(PROTOCOL
CONVERTERS)
•Gateways are protocol converters. It accepts the packet
formatted for one protocol and converts the formatted
packet into another protocol.
•It is an internetworking device, which joins two different
network protocols together.
•It works on all the 7 layers of the OSI model.
GATEWAY

MODEMS
An illustration of data sent using a modem and a
regular telephone line.
A modem is a device that converts digital data
originating from a terminal or computer, to analog
signals used by voice communication networks such as
the telephone system.
At one end, modems convert the digital pulses to
audible tones and convert audio tones back to digital
pulses at the other.
The word "Modem" stands for:
"Modulator- Demodulator"

 Transmission speed
Modems are available in different transmission speeds,
which are measured in BPS (bits per second) also called
BAUD rate.
Standard modems speeds: 9600 baud, 14400 baud, 28800
baud, 33600 baud, 56800 baud.
 TYPES- Internal/External
Internal modems are electronic cards. An internal modem
is installed in one of the computer's expansion slot.
External modems are fully functioning external devices.
The external modem is connected to a computer using a
serial cable to one of the computer's serial ports, and
draws power from an external power source.
THANK YOU
MODEMS

Networking: A Beginner's Guide

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