COMPUTER NETWORK & ITS BUSINESS

APPLICATIONS
 COMPUTER NETWORK

• A computer network is a system of

interconnected computers and peripheral
devices.
• For example, it may connect computers,
printers, scanners and cameras.
 COMMUNICATIONS

• Communication is about the transfer of

information from a sender, across a distance, to
a receiver.
• Communication is an act of transmitting
messages.
COMPUTER NETWORK COMMUNICATION

• We transmit information or data by using two

types of signals, namely analog and digital.
• Computers communicate with digital
signals.
• The older forms of communication
technology, such as telephones and radios,
use analog signals.
 TYPES OF NETWORKS

LOCAL AREA METROPOLITAN WIDE AREA

NETWORK AREA NETWORK
NETWORK
 LOCAL AREA NETWORK (LAN)
• Smallest network compared to the other two
networks.
• The simplest form of LAN is to connect two
computers.
• LAN is operated within a limited physical area,
such as at home, school, a single building or
several buildings.
• A network that consists of less than 500
interconnected devices across several buildings, is
still recognized as a LAN.
 METROPOLITAN AREA
NETWORK (MAN)
• ‘Metropolitan' - describes important cities like
New Delhi, Mumbai, Kolkata, bangaluru,
Chennai etc.
• Companies that have several branches within
the Mumbai city such as banks, use a MAN.
• Can be a collection of several LANs within the
same city.
• MAN can be defined as a group of computers
and network devices connected together within a
large physical area.
 WIDE AREA NETWORK (WAN)
• The largest network of all network types.
• Internet is the largest WAN in the world.
• WAN generally covers large distances such as
states, countries or continents.
• Eg: Local banks have always maintained their
business online by connecting all computers of
their branches in the countries. International
banks also use WAN to connect their computers
all over the world.
• WAN is a group of MANs or LANs or the mixture
of both networks.
COMPARISON OF LAN, MAN,
WAN
NETWORK ARCHITECTURE
• Overall design of a computer network
that describes how a computer
network is configured and what
strategies are being used.
• Mainly focuses on the functions of
the networks.
•NETWORK
Also known as network model or
ARCHITECTURE
network design.
 CLIENT/SERVER NETWORK

• A client/server network is a network

in which the shared files and
applications are stored in the
server but network users (clients)
can still store files on their
individual PCs.
• A server is a computer that shares
information and resources with
other computers on a network.
• A client is a computer which
NETWORK
requests services orARCHITECTURE
files from a
server computer.
 Peer-to-peer or P2P
• It is a network with all the nodes
acting as both servers and
clients.
• A PC can access files
located
on another PC and can also
provide files to other PCs.
• All computers in the peer-
to-
peer network has equal
responsibilities and
NETWORK ARCHITECTURE
capabilities
to use the resources available
on the network.
• With peer-to-peer network, no
server is needed; each
DIFFERENCES
NETWORK TOPOLOGY
TOPOLOGY DEFINITION - 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 TRANSFER BETWEEN NETWORK NODES.
  BUS
DESCRIPTION OF TOPOLOGY
BUS TOPOLOGY

 Very common in LAN.

A bus topology consists of a single central cable to which
 Must have a common backbone (the central
all computers and other devices connect. A bus topology is
cable) to connect all devices.
also known as a bus network.
 All nodes share the backbone to
communicate with each other on the
network.
 Sometimes, a bus network has more than
one server. Sometimes, a server is not
needed on the network.

•
 RING TOPOLOGY

A ring topology consists of all computers and other

devices that are connected in a loop. Ring topology is also
known as a ring network.

DESCRIPTION OF RING TOPOLOGY

• Can be found in LAN.

• Each node directly connect to two
neighbouring nodes.
• A server may exist in a ring network,
but it will not connect to all the nodes in
the network.
• The server, like other nodes, will only
communicate to its two neighbouring
nodes
 STAR TOPOLOGY

A star topology consists of a central host which acts as the

centre, and all nodes connect to the host. A star topology is also
known as star network.

DESCRIPTION OF STAR TOPOLOGY

• A star network is found in a Local Area

Network setting.
• A star network must have a host which
acts as the centre.
• The host can be a server, hub or
router.
• In a star network, every node will not
connect to the neighbouring nodes.
• Every node must connect to the host in
order to communicate.
• The host will control the flow of
communication in the
 TREE TOPOLOGY
Tree topology is the combination of the bus and the star
topology. The tree like structure allows you to have many
servers on the network and you can branch out the network
on many ways. Also known as hierarchical network.
DESCRIPTION OF TREE TOPOLOGY
•Nodes of some devices are linked to a
centrally located hub which is called the active
hub.
•The active hub has a hardware device
called the repeater.
•This strengthens the transmission and
increase the travelling distance of a signal.
•The secondary hub can isolate
communications between different computers.
 MESS TOPOLOGY
Mesh Network is a network where all the nodes are connected
to each other and is a complete network. In a Mesh Network
every node is connected to other nodes on the network
through hops. It is called the self healing technology where it
receives data one way or the other.

DESCRIPTION OF MESS TOPOLOGY

•Data is automatically configured to reach
the destination by taking the shortest route.
•The reliability factor is high in any kind of
Mesh Network.
•The Mesh Network is based on a very
sensible concept and has lesser chances of
a network breakdown.
 DIFFERENCES
Bus Topology Ring Topology Star Topology
Structure there is a single all computers and other there is a central host and
central cable (backbone) devices are all nodes
and all computers and connected in a circle connect to it
other devices connect to
it
Host existence depends on network depends on network needs yes
needs
Connection It has no connection yes no
between nodes between the nodes.
Host failure network can still run network will fail network will fail
Node failure network can still run network will fail network can still run
Ease of difficult. Need to depends on backbone. If there depends on the host. It
troubleshooting search for the is a backbone, is easier to repair the
problematic node one by troubleshooting is problematic host. However,
one difficult. If there is no if the nodes fail, then each
backbone, the focus is on the node has to be searched
two nodes not communicating
Ease of adding easy difficult average
or removing nodes

Number of nodes many limited limited

when extending
network
APPLICATIONS OF COMPUTER NETWORK

• File sharing.
• Printer sharing.
• Communication and collaboration.
• Remote access.
• Data protection.
• Centralized Support and Administration.
Network devices are components used
to connect computers or other
electronic devices together so that they
can share files or resources like printers or
fax machines.
 HUB

SWITCH

GATEWAY

BRIDGE

ROUTER

REPEATE

R
A hub is a common connection point
for devices in a network. Hubs are
commonly used to connect segments of a
LAN.
A hub contains multiple ports. When a
packet arrives at one port, it is copied to
the other ports so that all segments of
the LAN can see all packets.
A network switch (also called switching hub,
bridging hub, officially MAC bridge) is a
computer networking device that connects
devices together on a computer network by
using packet switching to receive, process,
and forward data to the destination device.
A network gateway is an internetworking
system capable of joining together two
networks that use different base protocols. A
network gateway can be implemented
completely in software, completely in
hardware, or as a combination of both.
Depending on the types of protocols they
support, network gateways can operate at any
level of the OSI model.
A NETWORK BRIDGE IS A COMPUTER
NETWORKING DEVICE THAT CREATES A
SINGLE AGGREGATE NETWORK FROM
MULTIPLE COMMUNICATION
NETWORKS OR NETWORK SEGMENTS.
THIS FUNCTION IS CALLED NETWORK
BRIDGING.
A router is a networking device that
forwards data packets between
computernetworks.
Routers perform the traffic directing functions
on the Internet. A data packet is typically
forwarded from one router to another router
through the networks that constitute the
internetwork until it reaches its destination
node.
A NETWORK DEVICE USED TO REGENERATE OR
REPLICATE A SIGNAL. REPEATERS ARE USED IN
TRANSMISSION SYSTEMS TO REGENERATE
ANALOG OR DIGITAL SIGNALS DISTORTED BY
TRANSMISSION LOSS.
TOPIC

OSI MODEL VS. TCP/IP

MODEL
OSI
MODEL
 Introduction
 The Open Interconnection (OSI)
Systems
 model is a reference tool for understanding data communications
between any two networked systems.
 There are also some benefits of OSI Model.
SEVEN
LAYERS
THE PHYSICAL
LAYER
 Physical Layer is responsible for transmitting
row bit stream over the physical cable.
 Functions:
o Data encoding
o Transmission technique
o Physical medium transmission
DATA LINK
LAYER
 Data link layer is responsible for controlling
the error between adjacent nodes and transfer
the frames to other computer via physical
layer.
 Functions:
o Link establishment and termination
o Frame traffic control
o Frame acknowledgment
THE NETWORK
LAYER
 This layer is responsible for translating the
logical network address and names into their
physical address.
 Functions :
o Subnet traffic control
o Logical-physical address mapping
o Frame fragmentation
THE TRANSPORT
LAYER
 This layer is responsible for end-to-end
delivers of messages between the
networked hosts
 Functions:
o Message segmentation
o Message acknowledgment
o Session multiplexing
THE SESSION
LAYER
 This layer is responsible for establishing the
process-to-process communication between
the hosts in the network.
 Functions:
o Session establishment, maintenance and
termination
o Session support
THE PRESENTATION
LAYER
 The Presentation layer is responsible for
protocol conversion, date
encryption/decryption, Expanding graphics
command and the date compression.
 Functions:
o Character code translation
o Data conversion
o Data compression
THE APPLICATION
LAYER
 The application layer provider different
services to the application.
 Functions:
o Remote file access
o Electronic messaging
o Directory services
o Network management
TCP/IP
MODEL

 TCP/IP are two protocols of this model. TCP

stands for Transmission Control Protocol
and IP stands for Internet Protocol.
 There are 4 Layers in TCP/IP Model.
APPLICATION
LAYER
 The Application Layer in TCP/IP groups the
functions of OSI Application, Presentation
Layer and Session Layer.
 Functions:
o Refers to standard network services
o Also defines compatible representation of
all data
TRANSPORT
LAYER
 In TCP/IP architecture, there are two Transport
Layer protocols. The Transmission Control
Protocol (TCP) guarantees information
transmission
 Functions:
o Manages the transfer of data
o Manages the connections between networked
applications
INTERNET
LAYER
 The Internet Protocol (IP) is the primary
protocol in the TCP/IP Network Layer.
 Functions:
o Manages addressing of packets and delivery of
packets between networks
o Fragments packets so that they can be dealt
with by lower level layer
NETWORK
LAYER
 In the TCP/IP architecture, the Data Link
Layer and Physical Layer are normally
grouped together to become the Network
Access layer
 Functions:
o Delivers data via physical link
o Provides error detection and packet
framing
OSI MODEL VS.TCP/IP
MODEL

 The OSI model consists of 7 architectural

layers whereas the TCP/IP only has 4 layers.
 OSI is a reference model and TCP/IP is an
implementation of OSI model.
 The OSI model however is
a "generic, protocol-independent standard.
 TCP/IP REFERENCE
Sr. OSI Reference
MODEL
No. Model

1 Defined after the advent of Defined before advent of internet.

Internet.

Service interface and protocols were Service interface and protocols are
2 not clearly distinguished before clearly distinguished

3 TCP/IP supports Internet working Internet working not supported

4 Loosely Strict layering

layered

5 Protocol Dependant Protocol independent standard

standard
6 More Less Credible
Credible

TCP reliably delivers packets, IP does

7 not All packets are reliably
delivered
reliably deliver packets