Form4 cd5

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COMPUTER NETWORKSAND COMMUNICATIONS

LESSON 67INTRODUCTION TO COMPUTER NETWORKSAND COMMUNICATIONS

COMPUTER NETWORK

A computer network is a system of interconnected computers and peripheraldevices. For example, it may connect computers, printers, scanners andcameras.

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 the form ofcodes are transmitted through aphysical medium such as wire, 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 byusing two types of signals, namelyanalog and digital.

Computers communicate with digital signals. The older forms ofcommunications technology, such as telephones and radios, use analogsignals.

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Therefore, in order to makecommunications possible fromcomputers, across telephones andradios and back to computers andother digital devices again, theremust be a signal translator, whichwe call — a modem.

The modem, which is short formodulator or demodulator,converts digital signals into analogand back again into digital signalsfor information to move across thetelephone line.

CONNECTIONS FOR NETWORKINGCommunications among computingdevices in a network can only happenthrough defined rules ofcommunications and connections.

In general, for communications in anetwork to be possible, there must be:

a physical medium — to allowdata to travel across it fromdevice to devicea 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 datatransmission sent from onedevice is received by theintended receiver.

If any of these levels of connectivityis missing, communications fornetworking 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 ‘understood’between devices.

If there is no network managementapplication available, there will beno means of ensuring thatinformation from one device will besent to the correct receiving device.

ProtocolOften simply referred to as a protocol, a communications protocol is a set ofrules or standards designed so that computers can exchange information witha 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 ‘Hardware’category.

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Operating systems and applications fallunder the ‘Software’ category.

NETWORK COMMUNICATION CHANNELS

Signals which carry informationin a communications systemtravel through a physicalmedium.

This physical medium is called acommunications channel, or atother times a communications link,a communications line, or acommunications medium.

Some common types of networkcommunications channels arethe:

twisted-pair wirecoaxial cablefiber-optic cablesatellite systemswireless systems (namely using radiowaves, microwaves andinfrared)

Communications channels provide the most basic levelof connectivity medium for a network.

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NETWORK INTERFACE CARDS ANDNETWORKING DEVICES

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

The NIC provides connectionbetween the computer and thenetwork’s communications media.

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

The Network Interface Card also suppliesthe basic addressing system used to getdata from PC to PC across a network.

The other hardware component that isrequired for communications to workon 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 anetwork, we will need to have suitable software on thenetwork computers that would be able to provide some basicfunctions, such as connecting to other computers on thenetwork, sharing resources and files and providing fornetwork security for users who are online.

In general, network software must be able to handle networking protocolsand connections within the network and with other networks. Mostimportantly, it should also provide file systems functions to organise diskspace on the network computers for sharing purposes.

Since most computer networks are connected to the Internet, networksoftware must have some form of management and security services toprotect the network as well as computers on the network, fromunauthorised access.

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LESSON 69IMPORTANCE OF NETWORKS AND COMMUNICATIONS

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 banks afterthey 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 onlylimited to the desktop computer users but also thosewho have mobile phones with wireless technology. Atpresent there are more than 7 million such users acrossthe 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. Technologicalsolutions 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 networked computergo online and continue their path of lifelong educationanywhere, 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 patients’database for easy retrieval. Unlike in conventionalpractice, doctors and nurses have to look for apatient’s 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 sellingbut 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 to buy.Payment is usually via credit card.

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

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 balanceand 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 can bedone 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 making anormal phone call and definitely faster and moreeffective than corresponding via letters of fax.

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

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LESSON 70TYPES OF NETWORKS

TYPES OF NETWORKS

Three types of networks:Local Area Network or LANMetropolitan Area Network or MANWide Area Network or WAN

Here:LAN - the email system within the school lab in SMK KLMAN - the email system within KL cityWAN - 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 instancea city.

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.

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LESSON 71LOCAL AREA NETWORK (LAN)

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

The simplest form of LAN is to connect two computerstogether.

LAN is operated within a limited physical area, such asat home, school, a single building orseveral buildings.

A network which consists of lessthan 500 interconnected devicesacross several buildings is stillrecognised as a LAN.

Inexpensive hardware used in LAN previously includestwisted pair, coaxial cables and the higher end is fiberoptic or wireless.

However, coaxial cables are now being replaced by ahigher 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 a group of computersand network devices connectedtogether, usually within the samebuilding.

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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.

MAN is a network of computers located atdifferent sites within a large physical area, suchas a city. Companies that have several brancheswithin the Kuala Lumpur city such as banks mightfind 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 ofseveral 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 be definedas a group ofcomputers andnetwork devicesconnectedtogether within alarge physical area.

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.

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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 MANsand LANs all over a largephysical area. A router is aspecial networking devicethat connects two or moredifferent networks and keepsdata flowing between 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.

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

LAN is also frequently used to provide a sharedconnection to other networks using a link to a WAN.

A MAN often acts as a high speed network to allowsharing of regional resources (similar to a large LAN). For larger networkcoverage, MAN is a better choice for a higher speed connection compared toa 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.

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

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.

COMPARISON OF LAN, MAN AND WAN

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LESSON 75NETWORK ARCHITECTURE

TYPES OF NETWORK ARCHITECTURE

Network architecture is theoverall design of a computernetwork that describes how acomputer network is configuredand what strategies are beingused.

Network architecture mainlyfocuses on the functions of thenetworks. Network architecture isalso known as network model ornetwork design.

There are two main network architectures:client/server networkpeer-to-peer network

CLIENT/SERVER NETWORK

A client/server network is a network inwhich the shared files and applicationsare stored in the server but networkusers (clients) can still store files ontheir individual PCs.

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

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PEER-TO-PEER NETWORKPeer-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 have equal responsibilitiesand capabilities 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 NETWORKOn a client/server network, shared files andapplications are stored in the server but network userscan still store files on their individual PCs.

A smaller client/server network uses twisted-pair orcoaxial cables for networking but a larger andpowerful network will use fibre optics. A client/servernetwork is suitable for connecting 10 or morecomputers.

To set up a client/server network, you need to installa 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 emailprograms are examples ofsoftware applications for aclient/server network.

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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 tasks and 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.A network server manages network traffic.

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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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 adocument.

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

For example, you have to be a TMnet orJaring member to use the internet service.You need to logon to TMnet or Jaring’sserver by sending your username andpassword.

After yoursuccessfullogin process,then you canaccess theinternetthrough TMnetor Jaring’sserver.

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.

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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,connect it to an existing wirelessnetwork and resources can beshared

Limewire, Bearshare and Kazaa areall examples of software applicationsfor peer-to-peer (P2P) file sharing.

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THE DIFFERENCES BETWEEN CLIENT/SERVERAND PEER-TO-PEER

LESSON 78NETWORK TOPOLOGY

Now, imagine replacing the dinner table as yournetwork, and the chairs are your computers. Howwould you like your network to be? How wouldyou arrange the computers?

In networking terms, the structure you areplanning to connect the computers to be callednetwork 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.

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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

Ring Topology

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LESSON 79BUS TOPOLOGY

In communications technology, you think of abus as a common “highway” on which data istransmitted.

A bus refers to the main physical pathway orcentral cable where all other devices areconnected to it. Like a major motor highway,all traffic flow will be affected if this main“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 TOPOLOGYBus 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 thenetwork. Sometimes, a bus networkhas more than one server. Sometimes,a server is not needed on the network.

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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.

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.

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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. Ringtopology is also known as a ring network.

A ring network can be found in Local AreaNetworks. In a ring network each nodedirectly connect to two neighbouring nodes.A server may exist in a ring network, but it willnot connect to all the nodes in the network.

The server, like other nodes, willonly communicate to its twoneighbouring nodes.

DEPENDENCE OF A RINGTOPOLOGYIf one of the nodes fails, the network will fail tofunction.

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.

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DISADVANTAGES OF A RING TOPOLOGY

Implementation is difficult. Network administrator has to terminate theentire network to install a new node between existing nodes.A failing node will affect the entire LAN.Connecting or removing devices is difficult because networkadministrator needs to terminate the network in order to do it.Network speed decreases when the number of nodes increases.

LESSON 81STAR TOPOLOGY

In the early days of computernetworking, all computers wereconnected to a centralised mainframecomputer.

All resources and management ofinformation were centred in this maincomputer.

The idea of a centralised mainframecomputer 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.

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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 stillfunction as long as the host is working.

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

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ADVANTAGES AND DISADVANTAGES OFSTAR TOPOLOGY

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

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

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Each topology has an influence on:the type of equipment we will usethe potential of the network in accommodating more computersthe way we manage our networkthe 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 allnodesconnect 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 failNode failure network can still run network will fail network can still

runEase oftroubleshooting

difficult. Need tosearch for theproblematic node oneby one

depends onbackbone. Ifthere is abackbone,troubleshooting isdifficult.

If there is nobackbone, thefocus is on thetwo nodes notcommunicating

depends on thehost. It is easierto repair theproblematic host.

However, if thenodes fail, theneach node has tobe searched

Ease of addingor removingnodes

easy difficult average

Number ofnodes whenextendingnetwork

many limited limited

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LESSON 83INTRODUCTION 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 andElectronic Engineers (IEEE), is oneinternational organisation responsible for developing andproviding networking technology specifications forworldwide usage.

We call these networking technology specifications asnetwork standards.

COMMON NETWORK STANDARDSNetwork communications use a variety of standards toensure that data travels correctly to its destination.

Network standards define guidelines that specify theway computers access the mediumto which they are attached.

The guidelines also describe the type of medium used, the speeds used ondifferent types of networks and the type of physical cable or wirelesstechnology used.

The well-known standards adopted by the Institute ofElectrical 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:802.3802.7802.8802.11

802.3 ETHERNET LANThe 802.3 standard is the standard for an EthernetLAN. In 802.3, Ethernet refers to the physicalcabling, while the way data is transmitted throughthe cable is called Carrier Sense Multiple Access!Collision Detection (CSMA! CD).

This method of transmission requires that only onedevice on the network can be transmitted at a time. If another device cansense that a transmission is already in the cable, it will have to wait. All theother devices on the network will also sense and wait until the line is clearbefore 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.

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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.

802.11 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 84PROTOCOLS

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

THE IMPORTANCE OF PROTOCOLSBefore protocols were developed, intercommunicationbetween devices was not possible. Protocols are importantas they define how devices, applications or computerscommunicate 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 specifythe format that the information bits or packetsmust contain when traveling across thisconnection.

There are also protocols that are responsible forensuring that the information bits or datapackets are sent or received in a propersequence.

All these protocols worktogether as a group toprepare and processdata for an exchange ofinformation over anetwork. We call such agroup a protocol stackor 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 fortransferring e-mail between computers.

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File Transfer Protocol (FTP) — FTP isresponsible for allowing files to be copiedbetween devices.

Transmission Control Protocol (TCP) — This protocol 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.

TCP/IP stands for Transmission Control Protocol / Internet Protocol.186

TRANSMISSION CONTROL PROTOCOL /INTERNET PROTOCOLTCP/IP (Transmission ControlProtocol / Internet Protocol) is theinternet communication protocol.

It is 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 tosurf a network, you will use the internet browser. Your browser then usesTCP/IP to request services from Internet servers. These servers will useTCP/IP to send the 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.

TCP is responsible for breaking the data into packets before they are sent.TCP then assembles the packets when they reach a destination.

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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 toaccess the internet. Let say yours is192.168.0.1.

When you access a web page, forexample the Yahoo main page, theTCP/IP will make the communicationwork between your computer and theYahoo server.

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First, you type the URL address“www.yahoo.com”on the browser. TheTCP 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, allowsthis to happen simultaneously. Land-line telephone networks are full-duplex since theyallow both 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 to‘www.yahoo.com’ or 209.131.36.158.

The Internet is a huge collection ofnetworks. 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 twocomputers. TCP will close thecommunication link once the web pagehas reached your computer.

LESSON 87PRIVATE COMPUTER NETWORK SETTING

Similar to mobile phones, computers connected to a network have:A phone number (an IP address on a network).Service provider identification, for example Maxis 012, Digi 016and Celcom 019 (a subnet mask on a network).Antennas (a network gateway on a network).A phone book function to help user put names totelephone numbers (a DNS server on a network).

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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 onthe desktop and click the properties command.

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

3. In the network interface’s 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.

5. Type in the IP address in the IP address textbox, for example 172.28.11.100.

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

7. Enter a default gateway with your server’s IPaddress. Let’s say your server IP address is171.28.11.1.

8. Make sure Obtain DNS serveraddress automatically is chosen.

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

10.Click OK in the external interface’s Propertiesdialog 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 thee-banking services as shown in the video.

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

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INTERNETThe Internet, or the Net, is the worldwide, publiclyaccessible system of interconnected computernetworks that transmit data by packet switchingusing the standard Internet Protocol (IP).

It consists of millions of smaller business,academic, domestic and government networks,which together carry various information andservices, such as electronic mail, online chat, andthe interlinked Web pages and other documents ofthe World Wide Web.

Internet is one of the uses ofcommunication. Through the Internet,society has access to global informationand instant communication.

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 usesInternet protocols, network connectivity and possiblythe public telecommunication system to securelyshare part of an organisation’s information oroperation with its employees.

Intranet generally makes company information accessible to employees andfacilitates 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 business’s informationor 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 inscientific 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 world’slargest computer networkwhich connects millions ofcomputers all over the world.

Many organisations includingprivate as well as governmentagencies, educationalinstitutions and individuals areconnected to the Internet.

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Some of the many usages of the Internet are:Information; research & exchangeCommercereal time communicationbankingshoppingentertainmenteducationgaming

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 any otherorganisation specialising in providingaccess 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 is divided 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 browsingEmailFile transferNewsgroup; Message boardsMailing listsChat roomsInstant 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 of theInternet that exists within an organisation.

Intranet generally makes company informationaccessible to employees and facilitates working ingroups.

To access intranet, employees need to be online. To let theemployees access the intranet fro everywhere around theworld, every employee will be given the intranet address,user name and password.

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Intranet usually includes electronic publishing of materials related to anorganisation such as:

Telephone directoriesEvent calendarsEmployee handbookJob postingEmail servicesNews bulletinCompany formsStaff information

Intranets too are used to conduct moresophisticated tasks such as:

Groupware applications in projectmanagement.Remote discussion rooms (chat rooms)Group schedulingVideo conferencing

COMPARISON BETWEEN INTRANET ANDINTERNET

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