WhatisaNetwork?Anetworkconsistsoftwoormorecomputersthatarelinkedinordertoshareresources(suchasprintersandCDs),exchangefiles,orallowelectroniccommunications.Thecomputersonanetworkmaybelinkedthroughcables,telephonelines,radiowaves,satellites,orinfraredlightbeams.Thetwobasictypesofnetworksinclude:LocalAreaNetwork(LAN)WideAreaNetwork(WAN)YoumayalsoseereferencestoaMetropolitanAreaNetworks(MAN),aWirelessLAN(WLAN),oraWirelessWAN(WWAN).LocalAreaNetworkALocalAreaNetwork(LAN)isanetworkthatisconfinedtoarelativelysmallarea.Itisgenerallylimitedtoageographicareasuchasawritinglab,school,orbuilding.RarelyareLANcomputersmorethanamileapart.InatypicalLANconfiguration,onecomputerisdesignatedasthefileserver.Itstoresallofthesoftwarethatcontrolsthenetwork,aswellasthesoftwarethatcanbesharedbythecomputersattachedtothenetwork.Computersconnectedtothefileserverarecalledworkstations.Theworkstationscanbelesspowerfulthanthefileserver,andtheymayhaveadditionalsoftwareontheirharddrives.OnmanyLANs,cablesareusedtoconnectthenetworkinterfacecardsineachcomputer;otherLANsmaybewireless.SeetheTopology,Cabling,andHardwaresectionsofthistutorialformoreinformationontheconfigurationofaLAN.WideAreaNetworkWideAreaNetworks(WANs)connectlargergeographicareas,suchasFlorida,theUnitedStates,ortheworld.Dedicatedtransoceaniccablingorsatelliteuplinksmaybeusedtoconnectthistypeofnetwork.UsingaWAN,schoolsinFloridacancommunicatewithplaceslikeTokyoinamatterofminutes,withoutpayingenormousphonebills.AWANiscomplicated.ItusesmultiplexerstoconnectlocalandmetropolitannetworkstoglobalcommunicationsnetworksliketheInternet.Tousers,however,aWANwillnotappeartobemuchdifferentthanaLAN.AdvantagesofInstallingaSchoolNetworkSpeed.Networksprovideaveryrapidmethodforsharingandtransferringfiles.Withoutanetwork,filesaresharedbycopyingthemtomemorycardsordiscs,thencarryingorsendingthediscsfromonecomputertoanother.Thismethodoftransferringfiles(referredtoassneaker-net)canbeverytime-consuming.Cost.Networkableversionsofmanypopularsoftwareprogramsareavailableatconsiderablesavingswhencomparedtobuyingindividuallylicensedcopies.Security.Filesandprogramsonanetworkcanbedesignatedas"copyinhibit,"sothatyoudonothavetoworryaboutillegalcopyingofprograms.Also,passwordscanbeestablishedforspecificdirectoriestorestrictaccesstoauthorizedusers.CentralizedSoftwareManagement.Oneofthegreatestbenefitsofinstallinganetworkataschoolisthefactthatallofthesoftwarecanbeloadedononecomputer(thefileserver).Thiseliminatesthatneedtospendtimeandenergyinstallingupdatesandtrackingfilesonindependentcomputersthroughoutthebuilding.ResourceSharing.Sharingresourcesisanotheradvantageofschoolnetworks.Mostschoolscannotaffordenoughlaserprinters,faxmachines,modems,scanners,andCDplayersforeachcomputer.However,iftheseorsimilarperipheralsareaddedtoanetwork,theycanbesharedbymanyusers.ElectronicMail.Thepresenceofanetworkprovidesthehardwarenecessarytoinstallane-mailsystem.E-mailaidsinpersonalandprofessionalcommunicationforallschoolpersonnel,anditfacilitatesthedisseminationofgeneralinformationtotheentireschoolstaff.ElectronicmailonaLANcanenablestudentstocommunicatewithteachersandpeersattheirownschool.IftheLANisconnectedtotheInternet,studentscancommunicatewithothersthroughouttheworld.FlexibleAccess.Schoolnetworksallowstudentstoaccesstheirfilesfromcomputersthroughouttheschool.Studentscanbeginanassignmentintheirclassroom,savepartofitonapublicaccessareaofthenetwork,thengotothemediacenterafterschooltofinishtheirwork.Studentscanalsoworkcooperativelythroughthenetwork.WorkgroupComputing.Collaborativesoftwareallowsmanyuserstoworkonadocumentorprojectconcurrently.Forexample,educatorslocatedatvariousschoolswithinacountycouldsimultaneouslycontributetheirideasaboutnewcurriculumstandardstothesamedocument,spreadsheets,orwebsite.DisadvantagesofInstallingaSchoolNetworkExpensivetoInstall.Althoughanetworkwillgenerallysavemoneyovertime,theinitialcostsofinstallationcanbeprohibitive.Cables,networkcards,routers,andsoftwareareexpensive,andtheinstallationmayrequiretheservicesofatechnician.RequiresAdministrativeTime.Propermaintenanceofanetworkrequiresconsiderabletimeandexpertise.Manyschoolshaveinstalledanetwork,onlytofindthattheydidnotbudgetforthenecessaryadministrativesupport.FileServerMayFail.Althoughafileserverisnomoresusceptibletofailurethananyothercomputer,whenthefilesserver"goesdown,"theentirenetworkmaycometoahalt.Whenthishappens,theentireschoolmayloseaccesstonecessaryprogramsandfiles.CablesMayBreak.TheTopologychapterpresentsinformationaboutthevariousconfigurationsofcables.Someoftheconfigurationsaredesignedtominimizetheinconvenienceofabrokencable;withotherconfigurations,onebrokencablecanstoptheentirenetwork.MustMonitorSecurityIssues.Wirelessnetworksarebecomingincreasinglycommon;however,securitycanbeanissuewithwirelessnetworks.