COMPUTER NETWORKS AND COMMUNICATIONS

LESSON 67INTRODUCTION TO COMPUTER NETWORKS ANDCOMMUNICATIONS

COMPUTER NETWORK

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

Us

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ing 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.

Computers communicate withdigital signals. The older forms ofcommunications technology, suchas telephones and radios, useanalog signals.

Therefore, in order to make

We transmit information or data byusing two types of signals, namelyanalog and digital.

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communications possible from computers, across telephones and radios and back to computers and other digital devices again, theremust be a signal translator, which we call – a modem.

The modem, which is short for modulator or demodulator, converts digital signals into analog and back again into digital signals for information to move across the telephone line.

CONNECTIONS FOR NETWORKINGCommunications 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 allow data to travel across it fromdevice to devicea set of rules called protocolsto ensure that interconnected computing 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.

If protocol between interconnecteddevices are not the same, datatransmission will not be ‘understood’between devices. If there is nonetwork management application

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available, there will be no means of ensuring that information from onedevice will be sent 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 informationwith a minimal errors.

LESSON 68COMPONENTS OF COMMUNICATIONS

INTRODUCTION

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

Computers, hub, switch, router, network interface cards and both wired and wireless communicationsmedia fall under the ‘Hardware’ category.

Operating systems and applications fallunder the ‘Software’ category.

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NETWORK COMMUNICATION CHANNELS

Signals which carry information in a communications system travel through a physicalmedium.

This physical medium is called a communications channel, or at other times a communications link, a communications line, or a communications medium.

Some common types of network communications channels arethe:

twisted-pair wirecoaxial cablefiber-optic cablesatelite systems wireless systems (namely using radiowaves, microwaves andinfrared)

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

NETWORK INTERFACE CARDS AND NETWORKINGDEVICES

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

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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 supplies the basic addressing systemused to get data from PC to PC across anetwork.

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 is generally to control the flow of data ona network.

NETWORK SOFTWARE

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The NIC provides connection between the computer and the network’s communications media.

How do computers communicate on a network?

Once we have got the necessary hardware set up for a network, we willneed to have suitable software on the network computers that would beable to provide some basic functions, such as connecting toother computers on the network, sharing resources andfiles and providing for network security for users who areonline.

In general, a network software must be able to handle networking protocols and connections within the network and with other networks. Mostimportantly, it should also provide file systems functions to organise 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 toprotect the network as well as computers on the network, fromunauthorised access.

LESSON 69

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APPLICATION 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 onlylimited 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. 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 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 ANDCOMMUNICATIONS Information 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 tobuy. Payment is usually via credit card.

Online Education160

With a network connections, online education is made possible. Students atany location around the world can participate in an online classroom,download tutorial questions 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 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 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.

LESSON 70TYPES OF NETWORKS

TYPES OF NETWORKS

Three types of networks:

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Here:

Local Area Network or LANMetropolitan Area Network or MANWide Area Network or WAN

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.

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 devices across several buildings, is still recognised 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 system such as CAT5 using RJ45 connectors.

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

Local Area Network is a groupof computers and networkdevices connected together,usually within the samebuilding.

LESSON 72METROPOLITAN AREA NETWORK (MAN)

First, you have to understand the wordmetropolitan. Metropolitan describes important 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 ofseveral LANs within the same city.

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

MAN can bedefined as a groupof computers andnetwork devicesconnectedtogether 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.

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A device called a router isthe MANs and LANs all over aA router is a specialthat connects two or moreand keeps data flowing

A router makes all thedifferent networkscommunicate, such as connecting LAN to LAN, LAN toWAN or WAN to WAN.

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 74

needed to connectlarge physical area.networking devicedifferent networksbetween them.

DIFFERENCES 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 informationfollowed by MAN and WAN. In addition, LANs arecapable of transmitting data at very fast rates, much

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faster than data which is transmitted over a telephone line although thedistances are limited.

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 as fibre-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 less than 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 configuredand what strategies are beingused.

Network architecture mainlyfocuses on the functions of thenetworks. Network architecture

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is also known as network model or network design.

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

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 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 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 76

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CLIENT / 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 or coaxial 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 install a server program for the server and a client program for the clients. A network administrator needs to configure access rights on the server side to allow access 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 email

program are examples of software applications for a client/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 SERVER

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Dedicated 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.

CLIENT The 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.

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For example, you have to be a TMnet or Jaring member to use the internetservice. You need to logon to TMnet or Jaring’s server by sending yourusername and password.

After youryou canTMnet orJaring’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 can also 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.

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successful login process, thenaccess the internet through

Wireless networking can be an example of a P2P network as you 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.

THE DIFFERENCES BETWEEN CLIENT/SERVER ANDPEER-TO-PEER

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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, is 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.

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 network topology. They are bus topology, star topology and ring topology.

Bus Topology

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Star Topology

LESSON 79BUS TOPOLOGY

Ring 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.

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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 to communicate with each other on thenetwork. Sometimes, a bus networkhas more than one server. Sometimes,a server 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.

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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.

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 to install 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.

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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.

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.

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.

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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 willfail 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

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UNDERSTANDING DIFFERENT TOPOLOGIES

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

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:

Structure

BusTopology

there is a single central cable(backbone) and allcomputers and otherdevices connect to it

RingTopology

all computers andother devices are connected in acircle

StarTopology

there is a centralhost and all nodes connect to it

Host existence depends on network needs

depends onnetwork needs

yes

Connection between nodes

It has no connectionbetween the nodes.

yes no

Host failureNode failure

network can still run network will failnetwork can still run network will fail

network will failnetwork can stillrun

Ease of troubleshooting

difficult. Need to search for the problematic node one

depends onbackbone. If thereis a backbone,

depends on thehost. It is easier to repair

by one troubleshooting is the problematicdifficult. If there is host. However, ifno backbone, the the nodes fail,focus is on the then each node

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Ease of adding or removing nodesNumber ofnodes whenextending network

easy

many

two nodes notcommunicatingdifficult

limited

has to be searched

average

limited

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

We call these networking technology specifications as network standards.

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

The well-known standards adopted by the Institute of Electrical and Electronic Engineers (IEEE) are the 802

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standards.These are the standards that define the requirements for physicalcabling and specify the way data is transmitted.

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.

802.8 WIRELESS LAN This 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

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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 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.

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

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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.

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

Transmission Control Protocol (TCP) – This protocol ensures thedelivery of information packets across network.

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

LESSON 85

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INTRODUCTION 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.

TRANSMISSION CONTROL PROTOCOL / INTERNETPROTOCOLTCP/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 tosend the web pages you requested back to your browser.

TRANSMISSION CONTROL PROTOCOL

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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.

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

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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.

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.

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maintain the linktwo computers. TCPcommunication linkpage has reached

LESSON 87

The Internet is a huge collection of networks. Thereare many routes from your computer to the server.IP will send the data packets through these routes asfast as possible. It will constantly use severaldifferent routes to deliver the packets to thedestination.

Meanwhile, TCPwill continue tobetween thewill close theonce the webyour computer.

PRIVATE COMPUTER NETWORK SETTING

Similar to mobile phones, computers connected to a network have:A phone number (an IP address on anetwork).Service provider identification, forexample Maxis 012, Digi 016 andCelcom 019 ( a subnet mask on anetwork).Antennas ( a network gateway on anetwork).A phone book function to help user putnames to telephone numbers ( a DNSserver 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 onthe desktop and click the properties command.

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

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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.

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

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7. Enter a default gateway with your server’s IP address. Let’s say yourserver IP address is 171.28.11.1.

8. Make sure Obtain DNS server addressautomatically is chosen.

9. Click OK in the(TCP/IP)

10.

Internet ProtocolProperties dialog box.

Click OK in the external interface’s

LESSON 88

Properties dialog box.

TYPES OF NETWORK COMMUNICATION TECHNOLOGY

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

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We use the Internet to communicate with each other, deal with moneytransaction, surfing for entertainment and 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.

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 theInternet, society has access to

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global information and 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 andpossibly the public telecommunication system tosecurely share part of an organisation’s 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.

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.

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Package shipping companies, for example, allow customers to access theirnetwork to print air bills, schedule pickups, and even track shipped packagesas the packages travel 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 network whichconnects millions of computersall over the world. Manyorganisations including privateas well as governmentagencies, educationalinstitutions and individuals are connected to the Internet.

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

Internet transmits data by using Internet Protocol (IP).

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To 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 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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LESSON 90INTRANET

INTRANET

INTERNET SERVICESInternet users can access services like:

Web browsingEmailFile transferNewsgroup&Message boardsMailing listsChat roomsInstant messaging.

With new technologies many of our taskscan be performed with a click of a fewbuttons. Company operations are nownot just limited within very tall buildingsor between two buildings located withinthe city. They are also available betweencities, states and even countries.

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

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USES OF INTRANET An 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 workingin groups.

To access intranet, employees need to be online. To letthe employees access the intranet fro everywhere aroundthe world, every employee will be given the intranetaddress, user name and password.

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

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 AND INTERNET

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