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COMPUTER NETWORKS (F4CD5)AND COMMUNICATIONS

LESSON 67INTRODUCTION TO COMPUTER NETWORKS AND

COMMUNICATIONS

COMPUTER NETWORK

A computer network is a system of interconnected computers and peripheral

devices. For example, it may connect computers, printers, scanners andcameras.

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Using hardware and software, these interconnected computing devices cancommunicate with each other through defined rules of data communications.In a network, computers can exchange and share information and resources.

A computer network may operate on wired connections or wirelessconnections.

When two or more networks are linked or connected and are able tocommunicate with one another using suitable hardware and software, it iscalled an internetwork.

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COMMUNICATIONSCommunications is about thetransfer of information from asender, across a distance, to areceiver.

Using electricity, radio waves or

light, information and data in theform of codes are transmittedthrough a physical medium such aswire, cable, or even the atmosphere.

The information that is transmitted(sent) can be text, voice, sound,video, graphics and images, or acombination of all these, which wecall multimedia.

We transmit information or data by

using two types of signals, namelyanalog and digital.

Computers communicate with digitalsignals.The older forms of communications technology, such as telephonesand radios, use analog signals.

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Therefore, in order to makecommunications possible fromcomputers, across telephonesand radios and back to computersand other digital devices again,there must be a signal translator,which we call a modem.

The modem, which is short formodulator or demodulator,converts digital signals intoanalog and back again intodigital signals for information tomove across the telephone line.

CONNECTIONS FOR NETWORKING

Communications among computingdevices in a network can onlyhappen through defined rules ofcommunications and connections.Ingeneral, for communications in anetwork to be possible, there mustbe:

a physical medium to allowdata to travel across it fromdevice to device

a set of rules called protocolsto ensure that interconnectedcomputing devices have thesame standards for exchangeof information to occursmoothly.

a system application formanaging network informationflow to ensure that data transmission sent from one device isreceived by the intended receiver.

If any of these levels of connectivityis missing, communications for

networking will not be possible.For example, if the physical mediumis cut off, there will be nocommunications.

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If protocol between interconnecteddevices are not the same, datatransmission will not be understoodbetween devices. If there is nonetwork management applicationavailable, there will be no means ofensuring that information from one

device will be sent to the correctreceiving device.

ProtocolOften simply referred to as a protocol, a communications protocol is a set ofrules or standards designed so that computers can exchange informationwith a minimal errors.

LESSON 68COMPONENTS OF COMMUNICATIONS

INTRODUCTION

In order for a network to properly operate, two categories of networkcommunications components are needed; Hardware and Software.

Computers, hub, switch, router,

network interface cards and bothwired and wireless communicationsmedia fall under the Hardwarecategory.

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Operating systems and applications fallunder the Software category.

NETWORK COMMUNICATION CHANNELS

Signals which carry informationin a communications systemtravel through a physical

medium.

This physical medium is calleda communications channel, or atother times a communicationslink, a communications line, ora communications medium.

Some common types of networkcommunications channels are

the: twisted-pair wire

coaxial cable

fiber-optic cable

satelite systems

wireless systems (namely using radiowaves, microwaves andinfrared)

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Communications channels provide the most basic level ofconnectivity medium for a network.

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NETWORK INTERFACE CARDS AND NETWORKINGDEVICES

The Network Interface Card or NIC is one of the mostimportant communications devices for a PC.

The NIC provides connectionbetween the computer and thenetworks communications media.

This connection is necessary becausethe NIC functions as a data conversiondevice to move data from the PCssystem to the network medium andvice versa.

The Network Interface Card alsosupplies the basic addressing systemused to get data from PC to PC across anetwork.

The other hardware component that isrequired for communications to work

on a network is the networking device,such as the hub, switch, router andeven the modem.

The function of these devices isgenerally to control the flow of data ona network.

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NETWORK SOFTWARE

How do computers communicate on a network?

Once we have got the necessary hardware set up for a network, we will needto have suitable software on the network computers that would be able toprovide some basic functions, such as connecting to other

computers on the network, sharing resources and files andproviding for network security for users who are online.

In general, a network software must be able to handlenetworking protocols and connections within the network and with othernetworks.Most importantly, it should also provide file systems functions toorganise disk space on the network computers for sharing purposes.

Since most computer networks are connected to the Internet, a networksoftware must have some form of management and security services to

protect the network as well as computers on the network, fromunauthorised access.

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LESSON 69APPLICATION SOFTWARE: ADVANCED FEATURES OFPRESENTATION SOFTWARE

Networking and communications technology is fast changing the way peopleview society and how we plan our daily social activities.

Through networking technology alone, many today arefinding friends online, visiting a library in anothercountry. Some people are able to go to the banksafter they are closed, as well as getting the latestdevelopment in news from within and outside thecountry.

Mobile communications today is also based on thenetworking technology. Surfing the internet is not only

limited to the desktop computer users but also thosewho have mobile phones with wireless technology. Atpresent there are more than 7 million such usersacross the world.

The internet has helped science and medical researchprogress further as doctors and researchers fromanywhere in the world can contribute and cooperate inany problem brought to their attention. Technological

solutions can be discovered quickly as individualscome forward to offer their help through the internet.

Homemakers, students, teachers, business people,and almost anyone with access to networkedcomputer go online and continue their path of lifelongeducation anywhere, anytime.

Organisations and individuals can make connectionsand establish communications within seconds withpeople nearby or overseas. Online communities can beformed and important issues and opinions to difficultproblems can be discussed without a threateningenvironment.

All these are now possible because of networks and communicationstechnology.

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IMPORTANCE OF NETWORKS ANDCOMMUNICATIONSInformation is now made easy with the availability of networkcommunications.

In a clinic for example, network communicationsplays an important part in keeping patientsdatabase for easy retrieval.Unlike in conventionalpractice, doctors and nurses have to look for apatients personal file from hundreds or maybethousands of records.With networkcommunication, the clinic saves time andmanpower allocation can be effectively planned.

E-BusinessE-business or electronic business refers toconducting business transactions on theinternet, not only limited to buying and selling

but also servicing customers and collaboratingwith business partners.

E-business supports many types of businesstransactions, including online shopping, sellingand renting. Users can browse the website andchoose from the list of items or services tobuy. Payment is usually via credit card.

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Online EducationWith a network connections, onlineeducation is made possible.Students at any location around theworld can participate in an onlineclassroom, download tutorialquestions and submit their

assignments.

E-BankingE-banking or electronic banking is the mostpopular banking facility nowadays. It handlesall types of banking transactions like accountmanagement, fund transfer and paymentsprimarily over the internet.

User can pay bills, check the account balance

and transfer money to other parties, using e-banking facilities twenty four hours a day andseven days a week.

With e-banking, most of the transactions canbe done at home or from the office, thus userssave time on traveling and queuing at the bankcounters.

Long Distance CommunicationLong distance communication is made easy vianetwork availability. Communication is possiblevia voice, text or video. The cost of having thistype of communication is cheaper than makinga normal phone call and definitely faster andmore effective than corresponding via letters offax.

In business, important decisions can effectivelymade through video conference meeting.

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TYPES OF NETWORKS

TYPES OF NETWORKS

Three types of networks:

Local Area Network or LAN

Metropolitan Area Network or MAN

Wide Area Network or WAN

Here:

LAN - the email system within the school lab in SMK KL

MAN - the email system within KL city

WAN - the email system between KL and London

A LAN covers a small region of space, typically a single building.

A MAN is a collection of LANs with the same geographical area, for instance acity.

A WAN can be a collection of LANs or MANs or the mix of two with a verylarge geographical area, for instance a country or even beyond the border.

LESSON 71LOCAL AREA NETWORK (LAN)

Local Area Network (LAN) is the smallest networkcompared to the other two networks.

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The simplest form of LAN is to connect two computers together.

LAN is operated within a limited physical area, such as at home, school, asingle building or several buildings.

A network which consists of less

than 500 interconnected devicesacross several buildings, is stillrecognised as a LAN.

Inexpensive hardware used in LAN previously includetwisted pair, coaxial cables and the higher end is fiberoptic or wireless. However, coaxial cables are nowbeing replaced by a higher speed cabling systemsuch as CAT5 using RJ45 connectors.

LAN is a very high speed network (from previously10Mbps) to 100Mbps, which is faster than MAN and WAN.

Local AreaNetwork is agroup of computers andnetwork devices connectedtogether, usually within the

same building.

LESSON 72METROPOLITAN AREA NETWORK (MAN)

First, you have to understand the wordmetropolitan. Metropolitan describesimportant cities such as Kuala Lumpur, Manila,Singapore, Tokyo, London and New York.

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MAN is a network of computers located at different sites within a largephysical area, such as a city. Companies that have several branches withinthe Kuala Lumpur city such as banks, might find a MAN useful to them.

In this case, setting up a MAN across longdistances can be best connected using fiberoptics. Sometimes, a MAN can be a collection of

several LANs within the same city.

MAN often acts as a high speed network(although not as fast as a LAN) to allowsharing of regional resources.

MAN can bedefined as a groupof computers andnetwork devices

connectedtogether within alarge physicalarea.

LESSON 73WIDE AREA NETWORK (WAN)

Wide Area Network (WAN) is the largest networkof all network types.The Internet is the largestWAN in the world.WAN generally covers largedistances such as states, countries orcontinents.

An example in the society using WAN is thebanking organisation. Local banks have alwaysmaintained their business online by connectingall computers of their branches in the countries.International banks also use WAN to connecttheir computers all over the world.

Actually, WAN is a group of MANs or LANs or themixture of both networks.

A device called a router isneeded to connect the MANs

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and LANs all over a large physical area.A router is a special networkingdevice that connects two or more different networks and keeps data flowingbetween them.

A router makes all the different networks communicate,such as connecting LAN to LAN, LAN to WAN or WAN toWAN.

The transmission media in WAN uses the fibre opticcable.WAN is still considered a fast network with speeds20 2000 Kbps, but slower than LAN and MAN.

LESSON 74DIFFERENCES BETWEEN TYPES OF NETWORK

SETTING UP COST

Setting up a MAN network is more expensive than a LANbut less than a WAN. Managers have to consider the costof buying the necessary hardware, software, medium andmaintenance service for the desired network.

NETWORK SIZEThe network size of a MAN falls between LANand WAN.As you know, a LAN usually coversonly a limited area such as a school lab; a MANwill cover a greater area such as a city while aWAN will cover the largest geographical areasuch as the size of Malaysia.

SPEEDLAN offers the best speed in transmitting information

followed by MAN and WAN. In addition, LANs arecapable of transmitting data at very fast rates, muchfaster than data which is transmitted over atelephone line although the distances are limited.

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LAN is also frequently used to provide a shared connection to other networksusing a link to a WAN.

A MAN often acts as a high speed network to allow sharing of regionalresources (similar to a large LAN). For larger network coverage, MAN is abetter choice for a higher speed connection compared to a WAN.

TRANSMISSION MEDIAA LAN uses the cheapest transmission mediacompared to MAN and WAN.Generally LAN only usescommunication media such as twisted-pair cables.

A MAN might have more than one transmission media since it involves acombination of two or more LANs and the media used depends on thenetwork coverage. Here, a MAN might use the twisted-pair and fibre-opticscables.

A WAN might use costlytransmission medias such asfibre-optics, radio waves andsatellites, depending on their

coverage.

CONNECTION LIMITThe number of computers that can be attached to a single LAN is limited.

A MAN can have a large number of computers compared to a LAN but lessthan a WAN.

A WAN can have up to billions of computers attached to it.

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COMPARISON OF LAN, MAN AND WAN

LESSON 75NETWORK ARCHITECTURE

TYPES OF NETWORK ARCHITECTURENetwork architecture is theoverall design of a computernetwork that describes how acomputer network is configured

and what strategies are beingused.

Network architecture mainlyfocuses on the functions of thenetworks.Network architectureis also known as network modelor network design.

There are two main network architectures:

client/server network

peer-to-peer network

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CLIENT/SERVER NETWORKA client/server network is a networkin which the shared files andapplications are stored in the serverbut network users (clients) can stillstore files on their individual PCs.

A server is a computer that sharesinformation and resources with othercomputers on a network. A client isa computer which requests servicesor files from a server computer.

PEER-TO-PEER NETWORK

Peer-to-peer or P2P network is anetwork with all the nodes acting asboth servers and clients. A PC canaccess files located on another PC andcan also provide files to other PCs.

All computers in the peer-to-peernetwork has equal responsibilities andcapabilities to use the resourcesavailable on the network.

With peer-to-peer network, no serveris needed; each computer in thenetwork is called a peer.

LESSON 76CLIENT / SERVER

CLIENT / SERVER NETWORK

On a client/server network, shared files andapplications are stored in the server but network userscan still store files on their individual PCs.

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A smaller client/server network uses twisted-pair orcoaxial cables for networking but a larger and powerful network will use fibreoptics. A client/server network is suitable for connecting 10 or morecomputers.

To set up a client/server network, you need to install

a server program for the server and a client programfor the clients. A network administrator needs toconfigure access rights on the server side to allowaccess for the clients to use the resources.

An email program is an exampleof a client program, as it sendsemail requests to a mail server.

IRC (Internet Relay Chat),

Internet browser and emailprogram are examples ofsoftware applications for aclient/server network.

SERVERA server is sometimes called ahost computer.A server is acomputer that providesservices to other computerscalled clients.A server controlsaccess to the hardware,software and other resourceson the network.

It provides a centralisedstorage area for programs,

data and information.

DEDICATED SERVERDedicated servers perform specific tasksand usually execute only one job.

For example, a file server stores andmanages files, a print server managesprinters and print jobs. A database serverstores and provides access to a database.

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A network server manages network traffic.

CLIENTThe client computers are computers on thenetwork that rely on the server for itsresources and services.

Client computers send requests to a serverfor resources or services to perform theirjob. For example, a client computer cansend a request asking permission to use theprinter attached to the server, to print a

document.

Usually a client computer has to log ontothe network using a user name andpassword to use the servers resources andservices.

For example,you have tobe a TMnet orJaringmember touse theinternet

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A dedicated server helps savetime and storage space in onecomputer. It will not put thewhole network at risk if it fails.

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service. You need to logon to TMnet or Jarings server by sending yourusername and password.

After your successful login process, then you can access the internet throughTMnet or Jarings server.

LESSON 77PEER-TO-PEER

PEER-TO-PEER FUNCTIONSPeer-to-peer (P2P) network is anetwork with all the nodesacting as both servers andclients. A PC can access fileslocated on another PC and canalso provide files to other PCs.

A P2P network usually usestwisted-pair or coaxial cablebecause these cables arecheaper and easier to workwith.

P2P network is the best choiceto set up a network with lessthan 10 computers.

P2P network is easier to manage aslong as there are network cardsinstalled on the PCs and connectioncan be done with a network cable.To share the resources, each PCmust have the necessary program.

There is no central server or centralrouter managing a P2P network.

Wireless networking can be anexample of a P2P network asyou only need a wireless card,

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connect it to an existing wireless network and resources can be shared

Limewire, Bearshare and Kazaa are all examples of software applications forpeer-to-peer (P2P) file sharing.

THE DIFFERENCES BETWEEN CLIENT/SERVER ANDPEER-TO-PEER

LESSON 78NETWORK TOPOLOGY

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Now, imagine replacing the dinner table as your network, and the chairs areyour computers.How would you like your network to be? How would youarrange the computers?

In networking terms, the structure you are planning to connect thecomputers to, is called network topology.

Network topology is alsoreferred to as the configurationof a network.

It usually refers to the physicalarrangement of the computersand other networking devicesthat are linked together.

It defines how nodes are connected to oneanother in a communication network.A networktopology must show the nodes and the linksbetween them.The nodes must be an activedevice connected to the network, such as acomputer, printer, hub or a router.

To see a network topology clearly, always apply it on a Local Area Network(LAN).According to the needs, there are three main types of networktopology. They are bus topology, star topology and ring topology.

Bus Topology

Star Topology

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Ring Topology

LESSON 79BUS TOPOLOGY

In communications technology, you think of abus as a common highway on which data istransmitted.A bus refers to the main physicalpathway or central cable where all otherdevices are connected to it.Like a major motorhighway, all traffic flow will be affected if thismain road is broken.

A bus topology consists of a single central cable to which all computers andother devices connect.A bus topology is also known as a bus network.

DESCRIPTION OF BUS TOPOLOGY

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Bus networks are very common in LocalArea Networks (LAN).A bus networkmust have a common backbone (thecentral cable) to connect all devices.

All nodes share the backbone tocommunicate with each other on the

network.Sometimes, a bus networkhas more than one server.Sometimes, aserver is not needed on the network.

DEPENDENCE OF A BUS TOPOLOGYIf one of the nodes fails, the bus network would still function as long as thebackbone is working.If the backbone fails, the network will fail to function.

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ADVANTAGES OF BUS TOPOLOGY

Easy implementation. New devices can be added to the backbone or tothe existing nodes.

Failure of a node doesn't affect the entire LAN.

No disruptions to the network when connecting or removing devices.

Network can easily be extended, by adding new devices to thebackbone or existing nodes.

DISADVANTAGES OF BUS TOPOLOGY

If the backbone fails, the entire bus network will be affected.

Network speed decreases when the number of nodes increases.

Troubleshooting is difficult when one of the nodes fails.

LESSON 80RING TOPOLOGY

A ring topology consists of all computers andother devices that are connected in a loop.Ring topology is also known as a ring network.

A ring network can be found in Local AreaNetworks.In a ring network each node

directly connect to two neighbouring nodes.A server may exist in a ring network, but it willnot connect to all the nodes in the network.

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The server, like other nodes,will only communicate to its twoneighbouring nodes.

DEPENDENCE OF A RING TOPOLOGYIf one of the nodes fails, the network will fail to function.

ADVANTAGES OF A RING TOPOLOGY

Troubleshooting is easy when one of the nodes fails.Repair or remove the failing nodes and the networkwill continue to function.

DISADVANTAGES OF A RING TOPOLOGY

Implementation is difficult.Network administrator has toterminate the entire network toinstall a new node betweenexisting nodes.

A failing node will affect theentire LAN.

Connecting or removing devicesis difficult because network administrator needs to terminate thenetwork in order to do it.

Network speed decreases when the number of nodes increases.

LESSON 81STAR TOPOLOGY

In the early days of computer

networking, all computers wereconnected to a centralised mainframecomputer.

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All resources and management of information were centred in this maincomputer.

The idea of a centralised mainframe computer is where the basic concept ofa star topology comes from.

A star topology consists of a central host which acts as the centre, and allnodes 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 neighbouringnodes.

Every node must connect to the host in order to communicate.

The host will control the flow of communication in the network.

DEPENDENCE OF A STAR TOPOLOGY

If one of the nodes fails, the star network can still

function as long as the host isworking.

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If the host fails, the network will fail to function.

ADVANTAGES AND DISADVANTAGES OF STARTOPOLOGY

Advantages

It is easy to implement. You only add nodes tothe host.

The failure of a node does not affect the entireLAN.

There are no disruptions to the network whenconnecting or removing devices.

The network can be extended by adding newdevices to the host or nodes.

Troubleshooting is easy when the host fails. Simply repair or replacethe host and the network will continue to function.

Disadvantages

If the host fails, the entire LAN will beaffected.

Network speed decreases when the numberof nodes increases.

Troubleshooting is difficult when one of thenodes fails.

A host must be installed to control thenetwork.

LESSON 82DIFFERENCES OF NETWORK TOPOLOGIES

UNDERSTANDING DIFFERENT TOPOLOGIES

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Understanding differences in network topologies helps us to see what eachtopology is able to do.

Each topology has an influence on:

the type of equipment we will use the potential of the network in accommodating more computers

the way we manage our network

the capabilities of the hardware to manage the flow of information

THE STRUCTURE NETWORK TOPOLOGYThe following table compares the structures of the three main types of thenetwork topologies:

BusTopology

RingTopology

StarTopology

Structure there is a singlecentral cable(backbone) and allcomputers and otherdevices connect to it

all computers andother devices areconnected in acircle

there is a centralhost and all nodesconnect to it

Host existence depends on networkneeds

depends onnetwork needs

yes

Connectionbetween nodes

It has no connectionbetween the nodes.

yes no

Host failure network can still run network will fail network will fail

Node failure network can still run network will fail network can stillrun

Ease oftroubleshooting

difficult. Need tosearch for theproblematic node oneby one

depends onbackbone. If thereis a backbone,troubleshooting isdifficult. If there is

no backbone, thefocus is on thetwo nodes notcommunicating

depends on thehost. Itis easier to repairthe problematichost. However, if

the nodes fail,then each nodehas to be searched

Ease of addingor removingnodes

easy difficult average

Number ofnodes whenextending

network

many limited limited

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LESSON 83

INTRODUCTION TO NETWORK STANDARDS

Network architectures are defined by exact anddetailed specifications regarding the physical layout,cabling and methods used to access and maintaincommunications in and between network media.

The Institute of Electrical and

Electronic Engineers (IEEE), is oneinternational organisation responsible for developing andproviding networking technology specifications forworldwide usage.

We call these networking technology specifications asnetwork standards.

COMMON NETWORK STANDARDS

Network communications use a variety of standardsto ensure that data travels correctly to itsdestination.Network standards define guidelines thatspecify the way computers access the mediumto which they are attached. The guidelines alsodescribe the type of medium used, the speeds usedon different types of networks and the type ofphysical cable or wireless technology used.

The well-known standards adopted by the Institute of

Electrical and Electronic Engineers (IEEE) are the 802standards.These are the standards that define therequirements for physical cabling and specify the way data istransmitted.

The ones we will get to know here are:

802.3

802.7

802.8

802.11

02.3 ETHERNET LANThe 802.3 standard is the standard for an EthernetLAN.In 802.3, Ethernet refers to the physical

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cabling, while the way data is transmitted through the cable is called CarrierSense Multiple Access/ Collision Detection (CSMA/ CD).

This method of transmission requires that only one device on the networkcan be transmitted at a time.If another device can sense that a transmissionis already in the cable, it will have to wait.All the other devices on thenetwork will also sense and wait until the line is clear before one of them can

transmit data along the cable.

802.7 BROADBAND LAN802.7 is the standard specifications for a Broadband LAN.This 802.7standard provides specifications for the design, installation and testingneeded for broadband transmissions.Broadband transmissions allowsimultaneous multiple transmissions or signals using differentcommunications channels at the same time.

802.8 FIBRE-OPTIC LAN AND MANSpecifications for a Fibre-Optic LAN and MAN are givenunder the 802.8 standard.This standard gives therecommendations for the configuration and testing offibre-optic Local Area Networks and Metropolitan AreaNetworks.

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802.8 WIRELESS LANThis standard defines communication between a wireless computer or clientand an access point or between two wireless computers or clients.

The 802.11 standard uses the 2.4GHz frequency band to transmit data up to2Mbps.

LESSON 84

PROTOCOLS

PROTOCOLSProtocols provide the rules on how computerscommunicate. They define how devicesintercommunicate in a network environment.

THE IMPORTANCE OF PROTOCOLSBefore protocols were developed, intercommunication

between devices was not possible.Protocols areimportant as they define how devices, applications orcomputers communicate in a network.

When two computers on a network perform a singleexchange of data or information, they will be busylooking for the best communication process betweenthem.

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For example, there will be a protocol to specify the format that theinformation bits or packets must contain when traveling across thisconnection.

There are also protocols that are responsible forensuring that the information bits or data packetsare sent or received in a proper sequence.

All these protocols worktogether as a group toprepare and processdata for an exchange ofinformation over anetwork.We call such agroup a protocol stack or

a protocol suite.

SOME TYPES OF PROTOCOLS

Hypertext Transfer Protocol (HTTP) This protocol is used to access,send and receive Hypertext Markup Language files (HTML) files on theInternet.

Simple Mail Transfer Protocol (SMTP) This protocol is used for transferring e-mailbetween computers.

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File Transfer Protocol (FTP) FTP is responsible for allowing files to becopied between devices.

Transmission ControlProtocol (TCP) Thisprotocol ensures the deliveryof information packets

across network.

Internet Protocol (IP) This important protocol is responsible forproviding logical addressing called IP address to route information betweennetworks.

LESSON 85INTRODUCTION TO TCP/IP

For communications across the Internet, we need to have protocols todemonstrate how data should be packaged and sent. TCP/IP is thecommunication protocol suite on the internet. It has a number of protocolscontrolling and handling data communication on the internet.

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TCP/IP stands for Transmission Control Protocol / Internet Protocol.

TRANSMISSION CONTROL PROTOCOL / INTERNET

PROTOCOLTCP/IP (Transmission ControlProtocol / Internet Protocol) is theinternet communication protocol. Itis a standard that sets the rulescomputers must follow incommunicating with each other ona network. Some refer TCP/IP asthe Internet Protocol Suite.

When you use any applications orprograms to access the Internet,these application will use TCP/IP toachieve the task. For example,when you want to surf a network,you will use the internet browser.Your browser then uses TCP/IP torequest services from Internet servers. These servers will use TCP/IP to sendthe web pages you requested back to your browser.

TRANSMISSION CONTROL PROTOCOL

TCP (Transmission Control Protocol) is the protocol that sets thecommunication rules between computers. Here, TCP establishes connectionbetween two computers, protects against data loss and data corruption.

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TCP is responsible for breaking the data into packets before they are sent.

TCP then assembles the packets when they reach a destination.

INTERNET PROTOCOL

IP (Internet Protocol) is the protocol that transfers data from node to node.Here, IP takes care of delivering data packets between two computers.IP isresponsible for sending the packets from sender to receiver.

LESSON 86THE WAY TCP AND IP WORK

Each computer must have an IP addressassigned by the network administrator to

access the internet. Let say yours is192.168.0.1.

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When you access a web page, for example the Yahoo main page, the TCP/IPwill make the communication work between your computer and the Yahooserver.

First, you type the URL addresswww.yahoo.comon the browser. The

TCP will send a request for the web pageon Yahoo server according to the addressyou typed in.

TCP will establish a connection betweentwo computers which is yours and Yahooserver and it will prepare the full-duplexcommunication.

A full-duplex system allows communication in both directions, and unlike half-duplex, allows

this to happen simultaneously. Land-line telephone networks are full-duplex since they allowboth callers to speak and be heard at the same time. A good analogy for a full-duplexsystem would be a two lane road with one lane for each direction

The IP will begin sending the datarequest from 192.168.0.1 towww.yahoo.com or 209.131.36.158.

The Internet is a huge collection of

networks. There are many routes fromyour computer to the server. IP willsend the data packets through theseroutes as fast as possible. It willconstantly use several different routesto deliver the packets to thedestination.

Meanwhile, TCP will continue tomaintain the link between the two

computers. TCP will close thecommunication link once the web pagehas reached your computer.

LESSON 87PRIVATE COMPUTER NETWORKSETTING

Similar to mobile phones, computersconnected to a network have:

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A phone number (an IP address on a network).

Service provider identification, for example Maxis 012, Digi 016 andCelcom 019 ( a subnet mask on a network).

Antennas ( a network gateway on a network).

A phone book function to help user put names to telephone numbers( a DNS server on a network).

STEPS TO SETTING UP PRIVATE NETWORKWhen you want to set up a private network for the school, you will need toinstall the network card, IP address, Subnet mask and Default gateway.

1. Right click on the My Network Places icon on thedesktop and click the properties command.

2. In the Network Connections window, right clickon the network interface and click theproperties command.

3. In the network interfaces Properties dialogbox, click the Internet Protocol (TCP/IP) entryand then click the Properties button.

4. In the Internet Protocol (TCP/IP) Propertiesdialog box, select the Use the following IPaddress option.

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5. Type in the IP address in the IP address text box, for example172.28.11.100.

6. Type in the Subnet mask in the subnet masktext box with 255.255.255.0

7. Enter a default gateway with your servers IPaddress. Lets say your server IP address is171.28.11.1.

8. Make sure Obtain DNS server addressautomatically is chosen.

9. Click OK in the Internet Protocol (TCP/IP)

Properties dialog box.

10. Click OK in the external interfacesProperties

dialog box.

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LESSON 88TYPES OF NETWORK COMMUNICATION TECHNOLOGY

The Internet has become one of thenecessary things in our daily lives. A lot canbe done via the Internet.

We use the Internet to communicate with each other,deal with money transaction, surfing for entertainmentand education.

For example, we can pay our utility bills using the

e-banking services as shown in the video.

The Internet is one of the types of networkcommunications technology besides intranet andextranet.

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The Internet, or the Net, is the worldwide, publicly accessible system ofinterconnected computer networks that transmit data by packet switchingusing the standard Internet Protocol (IP).

It consists of millions of smaller business, academic, domestic andgovernment networks, which together carry various information andservices, such as electronic mail, online chat, and the interlinked Web pages

and other documents of the World Wide Web.

Internet is one of the uses ofcommunication. Through theInternet, society has access toglobal information and instantcommunication.

INTRANET

An Intranet (intra means within) is an internal network that uses Internettechnologies and it is a small version of the Internet that exists within anorganisation.

An intranet is a private computer network that uses

Internet protocols, network connectivity andpossibly the public telecommunication system tosecurely share part of an organisations informationor operation with its employees.

Intranet generally make company information accessible to employees andfacilitate working in groups.

Simple intranet applications include electronic publishing of organisationalmaterials such as telephone directories, event calendars and job postings.

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EXTRANETAn extranet is a private network thatuses Internet protocols, networkconnectivity, and possibly the publictelecommunication system to securelyshare part of a businesss information

or operations with suppliers, vendors,partners, customers or otherbusinesses.

Package shipping companies, forexample, allow customers to accesstheir network to print air bills, schedule pickups,and even track shipped packages as the packagestravel to their destinations.

LESSON 89INTERNET

The Internet was created in the 1960s by people with great vision. They sawthe great potential value in allowing computers toshare information on research and development in

scientific and military fields.

Nowadays, when Internet is mentioned, it meansconvenience, speed and economical. Many tasks canbe accomplished without having to travel far, spendtoo much money or even wait for responses.

INTERNET

The Internet is the worldslargest computer network whichconnects millions of computersall over the world.Manyorganisations including privateas well as governmentagencies, educationalinstitutions and individuals areconnected to the Internet.

Some of the many usages of the Internet are: Information; research & exchange

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Commerce

real time communication

banking

shopping

entertainment

education

gaming

Internet transmits data by using Internet Protocol (IP).

INTERNET ACCESSTo access the Internet, users need tosubscribe services to an Internet ServiceProvider (ISP).An ISP can either be atelecommunication company or anyother organisation specialising inproviding access to Internet services.

Our Ministry of Energy, Water and Communications has licensed 6telecommunication companies to provide telephony services in Malaysia.Currently, only four of them are providing Internet services, they are Jaringby MIMOS, TMnet by Telekom Malaysia Berhad, Maxisnet by MaxisCommunications Bhd and Time.net by Time dotcom Berhad.

Internet connection isdivided into two

categories; dial-up or broadband.

For dial-up connections, a phone line and modem are needed to access theInternet while broadband connections use cable modem or router.

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INTERNET SERVICESInternet users can access services like:

Web browsing

Email

File transfer

Newsgroup&Message boards

Mailing lists

Chat rooms Instant messaging.

LESSON 90INTRANET

INTRANETWith new technologies many of our tasks canbe performed with a click of a few buttons.

Company operations are now not just limitedwithin very tall buildings or between twobuildings located within the city. They are alsoavailable between cities, states and evencountries.

The intranet technology allows sharing of valuable information and letsbusiness activities carry on even without a key personnel present at thebusiness premises.

USES OF INTRANETAn Intranet is an internal network that usesInternet technologies. It is a small version ofthe Internet that exists within an organisation.

Intranet generally make company informationaccessible to employees and facilitate working

in groups.

To access intranet, employees need to be online. To let theemployees access the intranet fro everywhere around the

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world, every employee will be given the intranet address, user name andpassword.

Intranet usually includes electronic publishingof materials related to an organisation suchas:

Telephone directories

Event calendars

Employee handbook

Job posting Email services

News bulletin

Company forms

Staff information

Intranets too are used to conduct moresophisticated tasks such as:

Groupware applications in projectmanagement.

Remote discussion rooms (chat rooms) Group scheduling

Video conferencing

COMPARISON BETWEEN INTRANET AND INTERNET

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