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8/13/2019 A Basic Concept of Network
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3.0 COMPUTER NETWORKS&
COMMUNICATION
3.1 Basic concepts of networks
and communication
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3.1.1 Definition
Computer networks
Definition : A collection of computers and devices
connected together via communication devices and
transmission media
Communication
Definition : A process in which two or morecomputers or devices transfer data, instructions and
information
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3.1.2 Importance of Computer Networks
Importance of
Computer
Network and
Communication
Share hardware,
Software andinformation
Cost reductionEasy to communicate
Can access
information
communicate with
each other from different
place
Data delivery
e.g: Email
Make a new
friends
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3.1.3 Types of Networks
LAN (Local Area Network)
MAN (Metropolitan Area Network) WAN (Wide Area Network)
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LAN (Local Area Network)
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A MAN is a high-speed network that
connects local area network in a metropolitanarea such as city or town an handles the bulk
of communication activity across that region.
A MAN typically includes one or more LANs,
but cover a smalller geographic area than aWAN.
MAN (Metropolitan Area Network)
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MAN (Metropolitan Area Network)
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WAN (Wide Area Network)
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Test your mind
computer server city Different country
2 3
1
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3.1.4 Network Architecture
The design of computers, devices, and
media in a network, sometimes called thenetwork architecture, is categorized as
Client/server
Peer-to-peer
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On a client/server network, one or more
computer act as server, and the othercomputers on the network request service
from the server
Client/server
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Client/serverThe file servers become the heart of the system,
providing access to resources and providing security.
Individual workstations (clients) have access to the
resources available on the file servers.
SERVER
CLIENT
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Peer-to-peer
Peer-to-peer network is asimple, inexpensive networkthat typically connects fewerthat 10 computers
Each computer (peer) hasequal responsibilities andcapabilities, sharinghardware (such as printer),
data or information withother computers
Each computer stores fileson its own storage devices
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TYPES OF
TOPOLOGY
NETWORK TOPOLOGY
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STAR TOPOLOGY
- nodes on a network are connected to hubor switch
- to prevent from collision- use dedicated link
- common network layout used today in LANlayout
- each workstation is connected point-to-pointto a single
central location
NETWORK TOPOLOGY
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Advantages Disadvantages
Easy to install and wire.
No disruptions to the network
then connecting or removing
devices.
Easy to detect faults and to
remove parts.
Requires more cable lengththan a linear topology.
If the hub or concentrator fails,
nodes attached are disabled.
More expensive than linear
bus topologies because of thecost of the concentrators.
STAR TOPOLOGY
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- Simpledesign
- Consists of a single cablethat forms the main data
path in the shape of a ring
- Each device is connected to a closed loopof cable
- Signals travel in one directionfrom one node to all
other nodes around the loop
- To prevent from collision
RING TOPOLOGY
NETWORK TOPOLOGY
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RING TOPOLOGY
Advantages Disadvantages
Since data travels in only one
direction, there is no danger of
data collision.
A failure in any cable or device
breaks the loop and can take
down the entire network.
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BUS TOPOLOGY
- The serveris at one end
- The client PCs(devices) are connected at different pointsor positions along the network
- All signals pass through eachof the devices
- It is easy get collision
NETWORK TOPOLOGY
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BUS TOPOLOGY
Advantages Disadvantages
Easy to connect a computer or
peripheral to a linear bus.
Requires less cable length
than a star topology.
Entire network shuts down if
there is a break in the maincable.
Terminators are required at
both ends of the backbone
cable.
Difficult to identify the problemif the entire network shuts down.
Not meant to be used as a
stand-alone solution in a large
building.
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DIFFERENTIATE
ASPECT RING BUS STAR
ARCHITECTURE
TRANSMISSION
OF DATA
Travel from device
to device around the
entire ring
The bus is the
physical cable that
connects thecomputers other
devices
Data transfers from
one node to another
note with passthrough the hub
RESPONS TME
Slowest Fast Faster
DISTRUPTION OF
NETWORK
AFFECTEDAffected Not Affected Not Affected
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3.1.6 Protocol
TCP/IP is a network standard or protocol that defines
how messages (data) are routed from one end of a
network to the other, ensuring the data arrivescorrectly
TCP/IP has been adopted as a network standard for
internet communication. Thus, all hosts on the
internet follow the rules defined in this standard
TCP/IP(Transmission Control Protocol/ Internet Protocol)
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3.1.7 Internet, Intranet, Extranet
Internetworldwide collection of networks
that links millions of businesses, government
agencies, educational institutions, and
individuals
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IntranetAn internal network in organization thatuses Internet technologies
Intranet generally make company informationaccessible to employees and facilitate working ingroups.
Intranet applications :1. Electronic publishing of organizational material such
as telephone directories, event calendars, proceduremanuals, employee benefits information, and job posting
2. Connection to internet
3. Groupware applicationssuch as project management,chat rooms, newsgroups, group scheduling, and videoconferencing
3.1.7 Internet, Intranet, Extranet
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Extranetpart of intranet that a company
allows its customer or supplier to access
Example : Package shipping companies,
allow customers to access their intranet to
print air bills, schedule pickups, and track
shipped packages as the packages travel totheir destinations.
3.1.7 Internet, Intranet, Extranet