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


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


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



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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.


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A Basic Concept of Network