computer-networks lecture 2 slide

7/26/2019 Computer-Networks Lecture 2 Slide

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Lecture 2

Introduction to Computer Network


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Networking

Computer network A collection ofcomputing devices that are connected in

various ways in order to communicate and

share resources(printer, file, dataase,music, etc!"

#sually, the connections etween

computers in a network are made usingphysical wires or cales

$owever, some connections are wireless,

using radio waves, infrared signals, etc!


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Components of a computer

network

hosts (%Cs, laptops, handhelds" routers & switches (I% router, 'thernet

switch"

links (wired, wireless" protocols (I%, C%, )%, $% etc!" applications (network services" humans and service agents $osts, routers & links form the hardware side! %rotocols & applications form the software

side!


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Networking

A network consists of two or more entities or

o*ects sharing resources and information!

A computer network consists of two or more

computing devices connected to each otherto share resources and information!

he network ecomes a powerful tool when

computers communicate and shareresources with other computers on the

same network or entirely distinct networks


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Networking+

he generic term nodeor hostrefers to any

device on a network

Communication the process of sending data

etween sender and receiver

Bandwidth: rate of data transfer.he speed

with which data is moved from one place on a

network to another!

-ata transfer rate is a key issuein computer

networks!


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Networking +

Computer networks have opened up an

entire frontier in the world of computing

called the client/server model

Figure 15.1 Client/Server interaction


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Networking

File server A computer that stores and

manages files for multiple users on a

network

We server A computer dedicated to

responding to re.uests (from the rowser

client" for we pages


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Need for Networks

A computer that operates independently

from other computers is called a stand/

alone computer!

he process of printing or transferring data

from one system to another using various

storage devices is called sneakernet!


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Need for Networks

'nhance communication!

0hare resources!

)acilitate centrali1ed management!


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Classification of Networks

Classification y network geography!

Classification y component roles!


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Classification y Network

eography

Networks are fre.uently classified

according to the geographical oundaries

spanned y the network itself!

LAN, 3AN, and 4AN are the asic types

of classification, of which LAN and 3AN

are fre.uently used!


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LAN

!ocal"area network#!$%& A networkthat connects a relatively small numer of

machines in a relatively close

geographical area!


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LAN opology

5arious configurations, called topologies, have een

used to administer LANs

6 'ing topolog( A configuration that connects all nodes

in a closed loop on which messages travel in onedirection

6 Star topolog( A configuration that centers around one

node to which all others are connected and through

which all messages are sent

6 Bus topolog( All nodes are connected to a single

communication line that carries messages in oth

directions


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LAN opology +

A us technology called )thernethas ecome the

industry standard for local/area networks

*arious network topologies

15"1+


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4AN

4etropolitan"area network#,$%&is a

network that interconnects users with

computer resources in a geographic area

or region larger than that covered y even

a large local area network (LAN" ut

smaller than the area covered y a(3AN"!


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4AN +!


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3AN

Wide"area network#W$%&7 A network that

connects two or more local/area networks over a

potentially large geographic distance!

6 3ANs span a larger area than a single city!6 hese use long distance telecommunication networks

for connection, therey increasing the cost!


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Wide area network

3AN +


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Classification y Component

8oles

Networks can also e classified according

to the roles that the networked computers

play in the network9s operation!

%eer/to/peer, server/ased, and client/

ased are the types of roles into which

networks are classified!


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8oles

%eer/to/peer7In a peer/to/peer network, all computers are

considered e.ual!

'ach computer controls its own informationand is capale of functioning as either a client

or a server depending upon the re.uirement!%eer/to/peer networks are ine:pensive and

easy to install!hey are popular as home networks and for

use in small companies!


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8oles

Peer-to-peer network


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8oles

0erver/ased7

A server/ased network offers centrali1ed

control and is designed for secure operations!

In a server/ased network, a dedicated server

controls the network!


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8oles

0erver/ased (continued"7

A dedicated server is one that services the

network y storing data, applications,

resources, and also provides access to

resources re.uired y the client!

hese servers can also control the network9s

security from one centrali1ed location or shareit with other specially configured servers!


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8oles

Server-based network


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0ummary

A network consists of two or more entities

sharing resources and information!

A computer network consists of two ormore computers that are connected and

are ale to communicate!


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0ummary

he asic purpose of networks is to

enale effective communication, share

resources, and facilitate centrali1ed

management of data!

Networks can e classified according to

their geographical oundaries or theircomponent roles!

computer-networks lecture 2 slide

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