2. Computer Network
A computer
network is a set
of computers
connected together.
Computers on a Network
called Nodes.
Connection Can be done
via cabling or wireless.
4. Data Communication Model
Source
Transmitter
Transmission System
Receiver
Destination
Generates the data
to be transmitted
Transforms and
encodes the
information
Complex Network
Connecting Source &
destination
Converts the received
signal into data
Takes incoming data
6. Topology
Topology refers to
the layout of
connected devices
on a network.
Here, some logical
layout of topology.
Mesh Star
Bus Ring
Hybrid
7. Mesh Topology
Here every
device has a
point to point
link to every
other device.
All the nodes are
connected to
other nodes with
a dedicated
connection.
8. Advantages And Disadvantages of Mesh
Topology
Advantages:
If any one link get damaged it
cannot affect others. It gives
privacy and security.(Message
travels along a dedicated link)
Disadvantages:
The amount of cabling and the number
of I/O ports required are very large.
Since every device is connected to each
devices through dedicated links.
9. Star Topology
Here each device has
a dedicated point-to-
point link to the
central controller
called “Hub”(Act as a
Exchange).
There is no direct
traffic between
devices.
The transmission are
occurred only through
the central “hub”.
Message to
PC 3
1 2
3 4
Hub
10. Advantages And Disadvantages of
Star Topology
Advantages:
If one device goes down, it has no
affect on the whole network.
Installation and configuration are
easy.
Less cabling is need then mesh.
Disadvantages:
Dependency (whole n/w
dependent on one single
point(hub). When it goes down.
The whole system is dead.
11. Bus Topology
A bus topology is
multipoint.
Here one long cable
act as a backbone to
link all the devices
are connected to the
backbone by drop
lines and taps.
Drop line- is the
connection b/w the
devices and the cable.
Tap- is the splitter
that cut the main
link.
This allows only one
device to transmit at
a time
P
1
P
2
P
3
P
4
Message to pc 3
T T
12. Advantages And Disadvantages of Bus
Topology
Advantages:
Easy for installation
Less cabling
If any station lies down it
has no affect on the
network.
Disadvantages:
If any fault in backbone can
stops all transmission.
P
1
P
2
P
3
P
4
TT
13. Ring Topology
The signal is passed in one
direction from device to
device until it reaches the
destination and each device
have repeater.
To add or delete a device
requires changing only
two connections.
1
2
3
4
Message to pc 3
14. Advantages And Disadvantages of Ring
Topology
Advantages:
1. Easy to install.
2. Easy to reconfigure.
3. Fault identification is
easy.
Disadvantages:
1. Unidirectional traffic.
2. Break in a single ring can
break entire network.
15. Hybrid Topology
A network which
contain all type of
physical structure
and connected
under a single
backbone channel.
16. OSI MOdel
Open Systems Interconnection Basic Reference Model (OSI Reference Model
or OSI Model) is an abstract description for layered communications and
computer network protocol design. It was developed as part of the Open
Systems Interconnection (OSI) initiative. In its most basic form, it divides
network architecture into seven layers which, from top to bottom, are the
Application, Presentation, Session, Transport, Network, Data-Link, and
Physical Layers. It is therefore often referred to as the OSI Seven Layer
Model.
18. Working of OSI Model
APPLICATION
PRESENTATION
SESSION
TRANSPORT
NETWORK
DATA LINK
PHYSICAL
APPLICATION
PRESENTATION
SESSION
TRANSPORT
NETWORK
DATA LINK
PHYSICAL
20. TCP/IP Model Layers
5
1
2
3
4
Application Layer
The Application layer provides applications the ability to access the
services of the other layers and defines the protocols that applications use
to exchange data.
Network Access Layer
Lowest layer of the all.
Protocol is used to connect to the host, so that the packets can be sent over
it. Varies from host to host and network to network
Physical Layer
This layer is generally thought of as referring to all hardware under the
Network Layer. This is the physical connection whether using a Network
Interface Card (NIC) or with a modem to connect to the local network.
Transport Layer
It decides if data transmission should be on parallel path or single path.
Functions such as multiplexing, segmenting or splitting on the data is done
by transport layer
Internet Layer
Selection of a packet switching network which is based on a connectionless
internetwork layer is called a internet layer.
It is the layer which holds the whole architecture together.
21. Working of TCP/IP
Model
Application Layer
Transport Layer
Network Access
Layer
Internet Layer
Physical Layer
Application Layer
Transport Layer
Network Access
Layer
Internet Layer
Physical Layer
22. TRansMIssIon MedIa
Transmission media is a pathway that carries the information
from sender to receiver.
We use different types of cables or waves to transmit data.
Data is transmitted normally through electrical or electromagnetic
signals.
23. Transmission media are located below the physical layer
Computers use signals to represent data.
Signals are transmitted in form of electromagnetic
energy.
Description
25. Guided Media - Twisted-pair cable
A twisted pair consists of two conductors
Basically copper based
With its own plastic insulation, twisted together
26. Provide protection against cross talk or interference(noise)
One wire use to carry signals to the receiver
Second wire used as a ground reference
For twisting, after receiving the signal remains same.
Therefore number of twists per unit length, determines the quality of cable.
Twisted Pair Description
Advantages:
Cheap
Easy to work with
Disadvantages:
Low data rate
Short range
27. Co-axial Cable
Co-axial cable carries signal of higher frequency ranges than twisted pair cable.
Inner conductor is a solid wire
Outer conductor serves as a shield against noise and a second conductor
28. Most versatile medium
Television distribution
Long distance telephone transmission
Can carry 10,000 voice calls simultaneously
Short distance computer systems links
Local area networks
Coaxial Cable Applications
ADVANTAGES
Easy to wire
Easy to expand
Moderate level of Electro Magnetic
Interference
DISADVANTAGE
Single cable failure can take down an
entire network
Cost of installation of a coaxial cable is
high due to its thickness and stiffness
Cost of maintenance is also high
29. Fiber-Optic Cable
A fiber optic cable is made of glass or plastic and transmit signals in the
form of light.
Nature of light:
Light travels in a straight line
If light goes from one substance to another then the ray of
light changes direction
Ray of light changes direction when goes from more dense to
a less dense substance
iber – Optic cable Connectors:
30. Areas of Application
• Telecommunications
• Local Area Networks
• Cable TV
• CCTV
• Medical Education
Advantages:
Greater capacity
Example: Data rates at 100 Gbps
Smaller size & light weight
Lower attenuation
Electromagnetic isolation
More resistance to corrosive
materials
Greater repeater spacing facility
Example: After every 10s of km
at least
Disadvantages:
Installation and maintenance need
expertise
Only Unidirectional light propagation
Much more expensive
31. Unguided Media – Radio Waves
Omnidirectional
Antenna
Frequencies between 3
KHz and 1 GHz.
Used for
multicasts(multiple way)
communications, such
as radio and television,
and paging system.
Radio waves can
penetrate buildings
easily, so that widely
use for indoors &
32. Antennas
An Antenna is a structure that is generally a metallic object may be a
wire or group of wires, used to convert high frequency current into
electromagnetic waves.
Antenna are two types:
Transmission antenna
Transmit radio frequency from transmitter
Radio frequency then
Convert to electromagnetic energy by antenna
Then, radiate into surrounding environment
Reception antenna
Electromagnetic energy get in antenna
Then Antenna convert radio frequency to electrical energy
Then, Goes to receiver
same antenna can be used for both purposes
33. Infrared
Frequencies between 300 GHz to 400 THz.
Used for short-range communication
Example: Night Vision Camera, Remote control, File sharing between two phones,
Communication between a PC and peripheral device,
