INTRODUCTION

INTRODUCTIONThe overwhelming need of organizations and

their workers is for connectivity, integration & ease of access to information.

The technology that is bringing all these together & making it possible is NETWORKING !

A Bank NetworkUses communication channel to connect Automated

Teller Machine (ATM) to its branch computer.Branch computers are connected to Headquaters

computers to update information.The network can be integrated with other bank to

share data & make transactions benefiting both banks.

Bank Branch Bank HQ

wire wire

ATM

DefinitionInformation

Is the result of processing, manipulating & organizing data in a many way that adds to the knowledge of a person receiving it.

Ex: of information is a picture, news, population of a country.

DataInformation stored on the computer system

used by applications to accomplish tasks.Ex : numbers & characters.

Need of Today’s Organization compared with Bank NetworkEasy storage, protection & retrieval of data

Ex: bank account holder data is protected & coded inside the chip of ATM/Smart card. The data is easily retrievable by trusted bank ATM.

Data sharing among its users & departmentsEx: the data (account holder information &

bank information) can be shared among bank employees from all over the branches.

Need of Today’s Organization compared with Bank NetworkFaster & safer flow of data

Ex: whole banking network system work fast & safe allowing KL customer to withdraw in any ATM in Kedah.

Management of huge volumes of data & across long distance.Ex: banking system holds account information,

profile data & transactions of millions of its customer in Malaysia.

Need of Today’s Organization compared with Bank NetworkInterconnectivity with other existing

technologies & inter exchange of data.One bank network is connected to other bank

network allowing Maybank customer to with draw money from HSBC ATM.

Ease of use & easy to learnATM is user friendly and has multiple language

option.

Data CommunicationDefinition : concerns itself with transmission

(sending/receiving) of information between 2 parties.

This means sending information between machines which are connected together by physical wires or radio links (wireless).

Physical wire can be twisted copper wire pair, coaxial cables or even fiber optics.

Ethernet hub/switch

Wireless Access Point

Communication System4 basic elements involved in a Communication

System;Sender –the party which initiates communicationMedium – the mechanism by which the

communication is conveyed to the receiverReceiver – the one who receives the signal sent by

the sender.Message – the information content that is transferred

between sender & receiver via the medium.

MESSAGE

mediumsender receiver

NetworksDefinition : a group of stations (computers,

telephone & other devices) connected by communication facilities for exchanging information.

A network can be connected to another network, thus making a bigger network.

A network can be part of other networks & it is known as sub-network.

Computer NetworkDefinition : a data communication system which

interconnects computer systems at various locations with the help of communication devices like hubs, router, cables & NICs.

Networking is done to facilitate data flow, implement security, share applications, resources & hardware.

Common computer networks are; Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Virtual Private Network (VPN), Intranet & Internet.

Why use a computer networks?Resource sharing

Ex: sharing of information, sharing hardware, sharing software & application

Centralizing administration & support

CommunicationEx : Email, IRC, Voice/Video conferencing,

Internet phone/VoIP)

Types of networksDepending on the size & coverage area of the

network, it can be classified into following groups.

Local Area Network - LANDef: Connects a group of computers in a small

geographical area such as in a building or office.Also known as high speed networks that connects

PC, printers & other network devices together in an organization.

Usually controlled by a single administrator due to its size.

Types of networksMetropolitan Area Network – MAN

Def : a backbone network that connects LANs in a metropolitan area such as a city or town.

It handles many communication activities or traffic.

Storage Area Network (SAN) – network designed to attach computer storage devices such as disk array controllers & tape libraries to servers.

Types of networksWide Area Network – WAN

Def : a computer network covering broad geographical areas such as state or country.

Data & information delivery is made via telephone lines, microwaves or satellites.

WAN is used to connect LANs & also MANs.The largest & well known WAN is Internet.

Types of networksVirtual Private Network – VPN

Def : private data networks that makes use of the public telecommunication infrastructures.

It is also a WAN but it is private & only that particular company people have access to it.

It maintains data privacy through the use of security procedures.

To give the company the capabilities of full access at much lower cost by using the shared public infrastructure like public telephone lines or internet rather than their own.

Types of networksIntranet

Def : private network of any organization which is only accessed by allowed users from the organization itself.

Main aim : to share part of the organization’s information & computer resources among its employees geographically dispersed.

Also used to monitor workgroup or teleconferencing within the organization.

External users can not access the company data.Ex : leave management system, human resource

system

Types of networksExtranet

Def : private network of an organization that allows trusted external partners or clients such as suppliers, customer or business partners to access the network.

An intranet extended to trusted external parties becomes extranet !

External parties would have limited access as compared to internal employee.

Network topology Def : the method used to do the physical

configuration of cables, computer & network devices.

Choice of topology is dependent upon:Type & number of equipment being used.Planned applications & rate of data transfer.Required response times.Cost

Ex of network topologies : linear bus, star, ring, mesh, hybrid, tree.

Linear Bus TopologyDef : all devices are connected to a central

cable, called the bus or backbone.Advantages: inexpensive & easy to install for

small networks.It has a single cable with terminator at each

end.

T-connector

Terminator

Linear Bus topologyFeatures:

Requires less cable length than star topologyEasy to connect a computer / peripheral to a

linear busEntire network shuts down if there a break in

the main cable.Difficult to identify the problem if the entire

network shuts down.Not meant to be used as a stand alone

solution in a large building.

Star TopologyFeatures a central connection point called a

hub.Many offices prefer to use star topologyDevices connected to the hub with

Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP).

hub

Star TopologyFeatures ;

All devices revolve around a central hub / switch.Switch / hub controls the network communications

& can communicate with other hubs.Easy to install.No disruptions to the network when connecting /

removing devices.Requires more cable length than bus topology.A failure in any network cable will only take down

one computer’s network access & not entire LAN.If hub fails = entire LAN fails !

Ring topologyEvery device has exactly 2 neighbours for

communication purposes.All messages travel through a ring in the same

direction (clockwise / anti clockwise).A Data Token is used to grant permission for

each computer to communicate.A failure in any cable or device breaks the loop

& can take down the entire network.Commonly used in campuses, school, buildings.

Ring topology

Mesh TopologyEach computer is connected to every other

computer by a separate cable.This configuration provides redundant paths,

so when one computer encounters problem, the entire network still works.

On large scale, multiple LANs can be connected using mesh topology with the help of telephone lines, coaxial cable or fiber optic cable.

Mesh topology

Tree TopologyCombines characteristics of linear bus and

star topologies.Consists of groups of star configured

workstations connected to a linear bus backbone cable.

Allows for expansion of existing network

Hybrid TopologyA combination of two or more of the previous

topologies.

Network ArchitecturesPeer -To-Peer Networks

Type of network in which each workstation has equivalent capabilities & responsibilities.

Individual computers may share hard drives, CDROM drives & other storage devices with other computers in the network. (Different from client/server set up)

8-port hubUTP Cat-5 cabling

Peer to Peer NetworksFeatures :

Peers acts as equals, merging the roles of clients & server

There is no central server managing the network

There is no central routerEvery computer can share the resources it has.

Network ArchitecturesClient-Server Network

A computer network where one or more computers are formed to be the server.

Other computers (clients) can request resources from the server.

Clients depends on the server for few resources such as files, devices, processing power & storage space.

The server controls access towards devices & software in the network & offers storage capacity for program, data & information.

Client-Server NetworksFeatures:

A well planned client/server system provides inexpensive networks.

The servers are easier to secure & maintain from one location.

Client/server computing uses a powerful server to store data.

Data is more secure in a client/server environment.Server backups can be scheduled to occur automatically.A server based networks can support thousand of users.Servers can be physically isolated for additional security.Sensitive data can be secure from unauthorized users.

Network DevicesNetwork Interface CardsHubSwitchRepeaterBridge RouterBrouterGatewayCable

Assignment 1 :

Explain what each devices !