Introduction
BeforetheinventionofwirelesslocalareanetworkWLAN,peoplemustfirstusephysicalcables-copperstrandedwirestoformanelectronicoperatingpathinordertoimproveEfficiencyandspeed,andlaterinventedopticalfiber.Whenthenetworkhasdevelopedtoacertainscale,peoplehavediscoveredthatthiskindofwirednetworkisverydifficulttobuild,disassemble,orre-layoutandrebuildontheoriginalbasis,andthecostandpricearealsoveryhigh,sotheWLANnetworkingmethodCameintobeing.
WLANstartedin1997.InJuneofthatyear,thefirstwirelessLANstandardIEEE802.11wasformallypromulgatedandimplemented,providingaunifiedstandardforwirelessLANtechnology,butthetransmissionrateatthattimewasonly1~2Mbit/s.Subsequently,theIEEEcommitteebegantoformulatenewWLANstandards,whichwerenamedIEEE802.11aandIEEE802.11b.TheIEEE802.llbstandardwasfirstformallypromulgatedinSeptember1999,anditsrateis11Mbit/s.TheimprovedIEEE802.11astandardwasofficiallypromulgatedattheendof2001,anditstransmissionratecanreach54Mbit/s,whichisalmost5timesthatoftheIEEE802.11bstandard.Nevertheless,theapplicationofWLANhasnotreallystarted,becausetheentireWLANapplicationenvironmentisimmature.
TherealdevelopmentofWLANstartedinMarch2003whenIntelfirstlaunchedtheCentrinoprocessorwithaWLANwirelessnetworkcardchipmodule.Althoughthewirelessnetworkenvironmentatthattimewasstillveryimmature,themostdevelopedUnitedStateswasnoexception.However,duetoIntel’sbundlingsales,coupledwiththeobviousadvantagesofCentrinochipssuchashighperformanceandlowpowerconsumption,manywirelessnetworkserviceprovidershaveseenbusinessopportunities.Atthesametime,theaccessrateof11Mbit/scanalsobeusedingeneralsmallLANs.Carryingoutsomedailyapplications,wirelessnetworkserviceprovidersinvariouscountriesbegantoprovideaccesstohotspotsinpublicplaces(suchasairports,hotels,coffeeshops,etc.).Infact,theysetupsomewirelessaccesspoints(AccessPoints,AP)tofacilitatemobilebusinesspeoplewirelessly.Goonline.
Aftermorethantwoyearsofdevelopment,wirelessnetworkproductsandapplicationsbasedontheIEEE802.llbstandardhavebeenquitemature,butafterall,theaccessrateof11Mbit/sisfarfrombeingabletomeetactualnetworkapplicationrequirements.
InJune2003,aftermorethantwoyearsofdevelopmentandseveralimprovements,anewstandard-IEEE802thatiscompatiblewiththeoriginalIEEE802.llbstandardandcanalsoprovide54Mbit/saccessrate.11gwasofficiallyreleasedundertheeffortsoftheIEEEcommittee.
Atpresent,the802.11n(fourthgeneration)and802.11ac(fifthgeneration)standardsarethemostwidelyused.Theycanworkinboththe2.4GHzfrequencybandandthe5GHzfrequencyband.ThetransmissionrateisUpto600Mbit/s(theoreticalvalue).Butstrictlyspeaking,onlythosethatsupport802.11acarereal5G.NowIamtalkingaboutroutersthatsupport2.4Gand5Gdual-band.Infact,manyroutersonlysupportthefourth-generationwirelessstandard,thatis,thedual-bandof802.11n.Thecheapestroutethatreallysupportsac5Gisfourtofivehundredyuanoreventhousandsofyuan.
Advantagesanddisadvantages
Advantages
⑴Flexibilityandmobility.Inawirednetwork,theplacementofnetworkequipmentisrestrictedbythelocationofthenetwork,whileawirelesslocalareanetworkcanbeconnectedtothenetworkatanylocationwithinthewirelesssignalcoveragearea.Anotherbiggestadvantageofwirelesslocalareanetworkisitsmobility.Usersconnectedtothewirelesslocalareanetworkcanmoveandstayconnectedtothenetworkatthesametime.
⑵Easytoinstall.Awirelesslocalareanetworkcaneliminateorminimizetheworkloadofnetworkwiring.Generally,aslongasoneormoreaccesspointdevicesareinstalled,alocalareanetworkcoveringtheentireareacanbeestablished.
3Itiseasytocarryoutnetworkplanningandadjustment.Forwirednetworks,changesinofficelocationsornetworktopologyusuallymeanrebuildingthenetwork.Rewiringisanexpensive,time-consuming,wastefulandtrivialprocess.WirelessLANcanavoidorreducetheoccurrenceoftheabovesituations.
⑷Easytolocatefaults.Onceaphysicalfailureoccursinawirednetwork,especiallyanetworkinterruptioncausedbyapoorlineconnection,itisoftendifficulttofindout,andahighpriceisrequiredtorepairtheline.Thewirelessnetworkiseasytolocatethefault,andthenetworkconnectioncanberestoredbyreplacingthefaultydevice.
⑸Easytoexpand.Therearemanyconfigurationsofwirelesslocalareanetworks,whichcanquicklyexpandfromasmalllocalareanetworkwithonlyafewuserstoalargenetworkwiththousandsofusers,andcanprovidefeaturesthatcannotbeachievedbywirednetworkssuchas"roaming"betweennodes.Becauseofthemanyadvantagesofwirelesslocalareanetwork,itsdevelopmentisveryrapid.Inrecentyears,wirelesslocalareanetworkshavebeenwidelyusedinenterprises,hospitals,shops,factoriesandschools.
Insufficiency
Insufficiencyofwirelesslocalareanetwork:Whilewirelesslocalareanetworkcanbringconvenienceandpracticalitytonetworkusers,italsohassomeshortcomings.Theshortcomingsofwirelesslocalareanetworkarereflectedinthefollowingaspects:(1)Performance.Wirelesslocalareanetworksrelyonradiowavesfortransmission.Thesewavesaretransmittedthroughwirelesstransmitters,andbuildings,vehicles,trees,andotherobstaclesmayhinderthetransmissionofelectromagneticwaves,whichwillaffecttheperformanceofthenetwork.⑵Speed.Thetransmissionrateofthewirelesschannelismuchlowerthanthatofthewiredchannel.Themaximumtransmissionrateofwirelesslocalareanetworkis1Gbit/s,whichisonlysuitableforpersonalterminalsandsmall-scalenetworkapplications.⑶Security.Inessence,radiowavesdonotrequiretheestablishmentofaphysicalconnectionchannel,andwirelesssignalsaredivergent.Intheory,itiseasytomonitoranysignalwithintheradiowavebroadcastrange,causingcommunicationinformationtoleak.
WirelessLANtopology
WirelesslocalareanetworkbasedonIEEE802.11standardallowstheuseof2.4GHzor5GHzradiofrequencybandintheISMfrequencybandthatdoesnotneedtobeauthorizedinthelocalareanetworkenvironmentforwirelessconnection.Theyarewidelyused,fromhomestobusinessestoInternetaccesshotspots.
SimplehomewirelessWLAN:InthemostcommonandcheapestexampleofhomewirelessLAN,adeviceactsasafirewall,router,switchandwirelessaccesspoint.Thesewirelessrouterscanprovideawiderangeoffunctions,suchasprotectingthehomenetworkfromoutsideintrusions.ItisallowedtoshareasingleIPaddressofanISP(InternetServiceProvider).ItcanprovidewiredEthernetservicesfor4computers,butitcanalsobeextendedwithanotherEthernetswitchorhub.Makeawirelessaccesspointformultiplewirelesscomputers.UsuallythebasicmoduleprovidesWi-Fifor2.4GHz802.11b/goperation,whilethehigher-endmodulewillprovidedual-bandWi-Fiorhigh-speedMIMOperformance.
Dual-bandaccesspointsprovide2.4GHz802.11b/g/nand5.8GHz802.11aperformance,whileMIMOaccesspointscanusemultipleradiofrequenciesinthe2.4GHzrangetoimproveperformance.Dual-bandaccesspointsareessentiallytwoaccesspointsasoneandcanprovidetwonon-interferingfrequenciesatthesametime,whilenewerMIMOdevicesincreasethespeedinthe2.4GHzrangeorhigher.The2.4GHzrangeisoftencrowdedandduetocostissues,manufacturershaveavoideddual-bandMIMOdevices.Dual-banddevicesdonothavethehighestperformanceorrange,butallowyoutooperateintherelativelylesscrowded5.8GHzrange,andiftwodevicesareondifferentbands,allowthemtooperateatfullspeedatthesametime.Examplesinhomenetworksarenotcommon.Thistopologyismoreexpensivebutprovidesgreaterflexibility.Routersandwirelessdevicesmaynotprovideallthefeaturesthatadvanceduserswant.Inthisconfiguration,thecostofsuchanaccesspointmayexceedthepriceofacomparablerouterandAPall-in-onemachine,duetothefactthattherearefewersuchproductsinthemarket,becausemostpeopleliketocombinefunctions.Somepeopleneedhigherterminalroutersandswitchesbecausethesedeviceshavefeaturessuchasbandwidthcontrol,GigabitEthernet,andstandarddesignsthatallowthemtohavetheflexibilitytheyneed.
Wirelessbridging
WhenwiredtoEthernetorneedtoestablishasecondredundantconnectionforthewiredconnectionasabackup,wirelessbridgingallowswirelessconnectionsbetweenbuildings.802.11devicesareusuallyusedforthisapplicationaswellaswirelessfiberbridges.Basic802.11solutionsaregenerallycheaperanddonotrequiredirectvisibilitybetweenantennas,butaremuchslowerthanfiberopticsolutions.802.11solutionstypicallyoperateintherangeof5to30mbps,whilefiberopticsolutionsoperateintherangeof100to1000mbps.Theoperatingdistanceofthesetwobridgescanexceed10miles,andthe802.11-basedsolutioncanreachthisdistance,anditdoesnotrequireacableconnection.Butthedisadvantagesof802.11-basedsolutionsareslowspeedandinterference,whilefiberopticsolutionswillnot.Thedisadvantagesoffiberopticsolutionsarethehighpriceandthelackofdirectvisibilitybetweenthetwolocations.
Medium-sizedWLAN
Medium-sizedenterprisestraditionallyuseasimpledesign.Theysimplyprovidemultipleaccesspointstoallfacilitiesthatrequirewirelesscoverage.Thisparticularmethodisprobablythemostversatilebecauseofitslowentrycost,althoughitbecomesdifficulttomanageoncethenumberofaccesspointsexceedsacertainlimit.MostofthesewirelessLANsallowyoutoroambetweenaccesspointsbecausetheyareconfiguredonthesameEthernetsubnetandSSID.Fromamanagementperspective,eachaccesspointandtheinterfaceconnectedtoitaremanagedseparately.InmoreadvancedoperationsthatsupportmultiplevirtualSSIDs,VLANchannelsareusedtoconnectaccesspointstomultiplesubnets,butrequireEthernetconnectionstohavemanageableswitchports.TheswitchinthiscaseneedstobeconfiguredtosupportmultipleVLANsonasingleport.
Althoughitispossibletoconfiguremultipleaccesspointswithonetemplate,whenthefirmwareandconfigurationneedtobeupgraded,itstillbecomesdifficulttomanagealargenumberofaccesspoints.Fromasecurityperspective,eachaccesspointmustbeconfiguredtobeabletohandleitsownaccesscontrolandauthentication.TheRADIUSservermakesthistaskeasier,becausetheaccesspointcandelegateaccesscontrolandauthenticationtoacentralizedRADIUSserver,whichinturncanconnecttoacentraluserdatabasesuchasWindowsActiveDirectory.Butevenso,itisstillnecessarytoestablishaRADIUSassociationbetweeneachaccesspointandeachRADIUSserver,whichbecomesverycomplicatedifthenumberofaccesspointsislarge.
Large-scaleWLAN
Switchingwirelesslocalareanetworkisthelatestdevelopmentofwirelessnetworking.Thesimplifiedaccesspointiscontrolledbyseveralcentralizedwirelesscontrollers.DataistransmittedandmanagedthroughcentralizedwirelesscontrollersfrommanufacturerssuchasCisco,ArubaNetworks,Symbol,andTrapezeNetworks.Theaccesspointinthiscasehasasimplerdesigntosimplifythecomplexoperatingsystem,andmorecomplexlogicisembeddedinthewirelesscontroller.Accesspointsareusuallynotphysicallyconnectedtothewirelesscontroller,buttheyarelogicallyswitchedandroutedthroughthewirelesscontroller.TosupportmultipleVLANs,dataisencapsulatedinatunnelinsomeform,soevenifthedevicesareindifferentsubnets,thereisadirectlogicalconnectionfromtheaccesspointtothewirelesscontroller.Fromamanagementperspective,administratorsonlyneedtomanagewirelessLANcontrollersthatcancontrolhundredsofaccesspointsinturn.TheseaccesspointscanusesomecustomDHCPattributestodeterminewherethewirelesscontrolleris,andautomaticallyconnecttoittobecomeanextensionofthecontroller.ThisgreatlyimprovesthescalabilityofswitchedwirelessLANs,becausetheadditionalaccesspointsareessentiallyplug-and-play.TosupportmultipleVLANs,theaccesspointnolongerneedsaspecialVLANtunnelportontheswitchtowhichitisconnected,andcanuseanyoldaccessportonanyswitchorevenaneasy-to-managehub.TheVLANdataisencapsulatedandsenttothecentralwirelesscontroller,whichhandlesasinglehigh-speedmulti-VLANconnectiontothecorenetworkswitch.Securitymanagementhasalsobeenreinforced,becauseallaccesscontrolandauthenticationarehandledinacentralizedcontroller,ratherthanateachaccesspoint.OnlythecentralizedwirelesscontrollerneedstoconnecttotheRADIUSserver,andtheseserversareconnectedtotheActiveDirectoryinturnintheexampleshowninFigure6.
AnotherbenefitofswitchingwirelessLANsislow-latencyroaming.Thisallowsdelay-sensitiveapplicationssuchasVoIPandCitrix.Theswitchingtimewilloccurwithinapproximately50milliseconds,whichisusuallynotobvious.Thetraditionalwirelesslocalareanetworkwhereeachaccesspointisindependentlyconfiguredhasaswitchingtimeintherangeof1000milliseconds,whichwilldisruptphonecallsanddiscardapplicationsessionsonwirelessdevices.ThemaindisadvantageofswitchingwirelessLANsistheadditionalcostduetotheadditionalcostofthewirelesscontroller.ButinalargewirelessLANconfiguration,theseadditionalcostscaneasilybeoffsetbyeaseofmanagement.
Requirementsforestablishingawirelessnetwork
Aswirelesslocalareanetworksneedtosupporthigh-speedandburstdataservices,indoorusealsoneedstosolveproblemssuchasmultipathfadingandcrosstalkbetweensubnets.Specifically,thewirelesslocalareanetworkmustmeetthefollowingtechnicalrequirements:
1.Reliability:ThepacketlossrateofthewirelessLANsystemshouldbelessthan10-5,andthebiterrorrateshouldbelessthan10-8.
2.Compatibility:ForindoorwirelessLAN,itshouldbeascompatibleaspossiblewiththeexistingwiredLANinthenetworkoperatingsystemandnetworksoftware.
3.Datarate:InordertomeettheneedsofLANtraffic,thedatatransmissionrateofwirelessLANshouldbeabove54Mbps.
4.Communicationconfidentiality:Asdataistransmittedintheairthroughwirelessmedia,wirelesslocalareanetworksmusttakeeffectivemeasuresatdifferentlevelstoimprovecommunicationconfidentialityanddatasecurity.
5.Mobility:Supportfullmobilenetworkorsemi-mobilenetwork.
6.Energy-savingmanagement:Whenthereisnodatatransmissionandreception,thesitemachineisputintoasleepstate,anditisactivatedwhenthereisdatatransmissionandreception,soastoachievethepurposeofsavingpowerconsumption.
7.Miniaturizationandlowprice:Thisisthekeytothepopularizationofwirelesslocalareanetworks.
8.Electromagneticenvironment:Thewirelesslocalareanetworkshouldconsidertheinfluenceofelectromagneticonthehumanbodyandthesurroundingenvironment.
WhensettingupawirelessLAN,itisoftennecessarytocarefullyconsidermanydetailsinordertosuccessfullybuildawirelessLANandensureitshighperformance.
1.WhenconnectingtoaremoteLANthroughawirelessLAN,thebuildingwheretheremoteLANislocatedshouldbeasvisibleaspossible.IfthewirelessLANneedstopassthroughobstaclessuchastallbuildingsordensetrees,thenbuildWirelessLANtransmissionperformancewillbeaffected,afterall,thoseobstacleswilldirectlyaffectthenormaltransmissionofwirelessLANdatasignals.
2.WhenthedistancebetweentheremotenetworkandthelocalLANisrelativelylong,thenetworktransmissionbandwidthcanbeappropriatelyreducedtoachievethepurposeoflong-distancedatatransmission.Ifyoureallyneedtocarryoutlong-distancewirelesstransmission,youmightaswelltrySetupawirelessLANrelaytransferstationinthemiddletoallowInternetsignalstobypassobstacles.Inawirelesslocalareanetwork,whennetworksignalsaretransmittedinshortdistances,inordertoensurethatthemaximumtransmissionbandwidthcanbeobtained,severalwirelessnetworkbridgesmustbeintegratedwitheachother,andtheantennaheightofthewirelesslocalareanetworkisbasicallynotaffected.
3.ItisalsoveryimportanttoproperlysettheantennaheightofthewirelessLAN.IftheantennaheightofthewirelessLANdeviceisnotsetappropriately,simplyrelyonmethodssuchasincreasingtheantennagainorincreasingthepoweramplification.Thewirelesstransmissioneffectwillbeverylimited.Thenyoucanconsiderarrangingtheantennaofthewirelessnodedeviceonthetopfloorofthebuilding,andtrytouseasmallantennatoensuretherelativeconcentrationofradiowaves,whichisbeneficialtoeffectivelyavoidinterferencefromotherwirelessLANsignals.
4.AlthoughthefrequencyhoppingtechnologyisusedforwirelessLANtransmission,itisdifficulttodetectthefrequencycarrieroftheInternetsignal.Inthisway,onlywhenbothpartieshavesetthesamenetworkIDnumber,wirelessInternetcanbeaccessed.Safetransmissionofsignals.IfyouwanttofurtherensuretheoperationalsafetyofthewirelessLAN,youcanalsoencryptthewirelessInternetsignal.
Networkingmode
CombineseveraldevicesinWLANtoformamulti-layered,wirelessandwiredcomputernetwork.Generallyspeaking,therearetwonetworkingmodesforwirelesslocalareanetworks,oneisaWLANwithoutafixedbasestation,andtheotherisaWLANwithafixedbasestation.
WLANwithoutafixedbasestationisaself-containednetwork,whichismainlysuitableforapeer-to-peernetworkformedbetweencomputerswithwirelessnetworkcards.AWLANwithafixedbasestationissimilartothemechanismofmobilecommunication.Thecomputerwithawirelessnetworkcardisconnectedtothenetworkthroughabasestation(wirelessAPorwirelessrouter).ThiskindofnetworkiswidelyusedandisusuallyusedtoextendthecoverageofawiredLANorasabroadbandTheaccessmethodofwirelessInternet.
WLANwithoutafixedbasestation
AWLANwithoutafixedbasestationisalsocalledawirelesspeer-to-peernetwork,whichisthesimplesttypeofwirelesslocalareanetworkstructure.TheWLANstructurewithoutafixedbasestationisacenterlesstopology.Thecommunicationrelationshipbetweenthedevicesconnectedthroughthenetworkisequal,butitisonlysuitableforasmallnumberofcomputerwirelessconnectionmethods(usually5hosts).Orwithinthedevice).
Thisnetworkingmodedoesnotrequirefixedfacilities.Itcanbeimplementedonlybyinstallingawirelessnetworkcardineachcomputer,soitisverysuitablefortheformationofsometemporarynetworks.
WLANwithfixedbasestations
Whenthenumberofcomputerusersinthenetworkreachesacertainnumber,orwhenastablewirelessnetworkplatformneedstobeestablished,theAPisgenerallyusedasThenetworkmodeofthecenter.
TheAP-centricnetworkingmodeisalsothemostcommonnetworkingmodeforwirelesslocalareanetworks.Inthismode,anAPisrequiredtoactasacentralstation,andallsites'accesstothenetworkissubjecttothisCentralcontrol.
Hardwareequipment
1.Wirelessnetworkcard.TheroleofthewirelessnetworkcardisbasicallythesameasthatofthenetworkcardintheEthernet.Astheinterfaceofthewirelesslocalareanetwork,itcanrealizetheconnectionandcommunicationbetweentheclientsofthewirelesslocalareanetwork.
2.WirelessAP.APistheabbreviationofAccessPoint.WirelessAPistheaccesspointandwirelessgatewayofthewirelesslocalareanetwork.Itsfunctionissimilartothehubinthewirednetwork.
3.Wirelessantenna.Whenthenetworkdevicesinthewirelessnetworkarefarapart,asthesignalweakens,thetransmissionratewilldropsignificantlysothatthenormalcommunicationofthewirelessnetworkcannotberealized.Atthistime,thereceivedortransmittedsignalmustbeenhancedwiththehelpofthewirelessantenna.
UserManagement
ThecontentoftheusermanagementofthewirelessLANincludestheemphasisonthemanagementofthefilesandchangerecordsofmobilephoneusersinthemobilecommunicationandthemanagementoftheuserdataoftheexchange;UsermanagementinbroadbandADSLnetworksemphasizesuserauthenticationmanagementandbillingmanagement,andofcoursealsoincludesuserinformationmanagement;distributedsystemsemphasizeusercreation,deletion,permissionsetting,registration,connection,andaccounting.ButallusermanagementisnothingmorethanthemaincontentthatusuallyincludessystemIPaddressallocation,userdatabasemanagement,userregistration,userlevelmanagement,userauthoritysettings,userlogs,andsystemworkingstatusmonitoring.
AftertheintroductionofthenewgenerationofInternetprotocolIPv6,theusermanagementofwirelessLANmainlydealswiththefollowingaspects:
IPaddressallocation
Thereisawirelesslinktothewirelessaccesspoint,sothereisnoIPaddressallocationproblem,butonceitenterstheaccessnetwork,theAPthataccessesthenetworkwillassignatemporaryIPtotheuser.ThisIPwillbeusedduringthecommunicationphase,andtheIPwillbeautomaticallyreleaseduntiltheuserleavesthenetwork.IPaddressallocationandmanagementinIPv6networksmainlyincludepassiveallocationandactiveacquisition.ActiveacquisitioniscalculatedthroughtherelevantprotocolsoftheIPv6protocolsuite,andismainlyobtainedthroughtheMACaddressofthenetworkcardusingaspecificalgorithm.PassiveallocationisObtainedbyrequestingaDHCPv6serverinthenetwork.
Database
Theuserdatabaseissetuptosavetheuser’sbasicpersonnelinformationsuchasname,gender,etc.Thepurposeistoforcetheusertoregisterwithrealname,andtochecktheuser’sinputwhenregisteringIsyourprofilecorrect.Whenauserlogsintothewebsiteforthefirsttimeforuserregistration,theentireregistrationprocesscanonlybecompletedwhentheenteredpersonalinformationisconsistentwiththecontentstoredinthedatabase,otherwisetheregistrationcannotbesuccessful.ThispartbelongstothecontentofapplicationlayermanagementanddoesnotrequiremuchchangeafterbeingcombinedwithIPv6.
Registration
Userregistrationisthebasisforclassificationandhierarchicalmanagementofenduserstoensuretheorderlyoperationofthesystem.Userregistrationinformationisthebasisforthesystemtodeterminewhetheravisitinguserisaregistereduser.Inordertopreventemployeeswithulteriormotivesfromregisteringunderfalsenames,theclient'sIPaddressandusername,userpasswordandotherpersonalinformationcanbebundledforverification.AfterbeingcombinedwithIPv6,theIPv6protocolitselfprovidesgoodsecurity,andwecanmakefulluseofsomeoftheadvantagesofIPv6tomakeuserregistrationmorecomplete.
Login
Whentheterminalaccessesthenetwork,thenetworkcanautomaticallyobtaintheIPaddressofthevisitingclient,andcomparetheIPaddresswiththerecordintheuserregistrationdatabasetoDeterminewhetherthevisitorisaregistereduser.Iftheclient’sIPaddress-relatedinformationisnotfoundinthedatabase,itindicatesthatitisaterminalthathasnotbeenregistered,anditwillbeguidedtoperformuserregistration:IftheIPaddressregistrationinformationexistsintheuserregistry,itindicatesthattheclienthasbeenregisteredAfterregistering,theuserwillbepromptedtoenterhispersonalinformation,name,password,etc.,andthencompareitwiththerecordintheuserregistrationdatabasetoverifytheuser'spasswordtoconfirmtheuser'sidentity.Theconfirmeduserwillbeautomaticallygivenanidentitybythesystem,andtheuser’sidentityinformationwhoselifetimecannotbeobtainedandchangedontheterminalcanbecontrolledbythesystem.
Levelsettings
Usersusuallyhaveaclearandfixedjobpositioninunitsandorganizations,belongingtoacertaindepartmentandgroup,andlocatedatacertainadministrativelevel.Differentlevelsofusersaresetbythesystemadministratorbasedonpersonnelinformationanduserregistrationinformation.AfterthispartiscombinedwithIPv6,thereisbasicallynochange,thatis,therewillnotbemuchchangeintheaccessWLANnetworkinthenext-generationall-IPnetwork.
Permissionsettings
Inordertopreventusersfromunauthorizedaccessandarbitraryinformationpublishingactivities,userpermissionsmustberestricted.Ofcourse,thishasnothingtodowiththespecificnetworkprotocol,sothereisnochangeinthenext-generationIPv6network.
Log
Userlogisthefirst-handdatatorecordtheclick-throughrateofuseractivitystatisticscolumnandanalyzeandimprovenetworkutilization.Theuserlogissavedinthedatabase,whichisconvenientforfuturestatisticalanalysis.Theuserloginformationcanbeusedforstatisticalanalysissuchastheinformationpublishedbythesiteandcolumnbrowsedbytheuserduringthelogintime.Thispartbelongstotheoperationoftheapplicationlayer.AftertheintroductionofIPv6technology,nochangesarerequired.
Applications
TherearemanyWLANimplementationprotocols,amongwhichthemostfamousandwidelyusedwirelessfidelitytechnologyisWi-Fi,whichactuallyprovidesaThetechnologythatuseswirelessinterconnectionofvariousterminalshasshieldedusersfromthedifferencesbetweenvariousterminals.
Inpracticalapplications,theaccessmethodofWLANisverysimple.TakingahomeWLANasanexample,onlyawirelessaccessdevice-arouter,andacomputerorterminal(mobilephoneorPAD)withwirelessfunctionsarerequired.Thecomputerwithoutwirelessfunctiononlyneedstopluginawirelessnetworkcard.Afterhavingtheaboveequipment,thespecificoperationisasfollows:Usetheroutertoconnectthehotspot(otherwirelessnetworksthathavebeenestablishedandinthereceivingrange)orwirednetworktothehome,andfollowtheinstructionsprovidedbythenetworkserviceprovidertoconfiguretherouting.Placethereceivingterminalwithinthecoveragearea(thestablecoverageoftheWLANisabout20m~50m),turnonthewirelessfunctionoftheterminal,andentertheusernameandpasswordgivenbytheserviceprovidertoaccesstheWLAN.
ThetypicalapplicationscenariosofWLANareasfollows:
(1)Betweenbuildings:Buildingnetworkconnectionsbetweenbuildingsinsteadofdedicatedlines,whichissimpleandcheap.
(2)Cateringandretail:Thecateringserviceindustrycanusewirelesslocalareanetworkproductstoinputandtransmitthecontentofguests’ordersdirectlyfromthediningtabletothekitchenandcounter.Retailerscanusewirelesslocalareanetworkproductstosetuptemporarycashiercounterswhenpromotingsales.
(3)Medicaltreatment:Useportablecomputerswithwirelesslocalareanetworkproductstoobtainreal-timeinformation,sothatmedicalstaffcanavoiddelaysintreatingpatients,unnecessarypaperwork,anddelaysindocumentcirculationAndmisdiagnosis,etc.,toimprovethequalityofcarefortheinjured.
(4)Enterprise:Whenemployeesintheenterpriseusewirelesslocalareanetworkproducts,nomatterwheretheyareinanycorneroftheoffice,theycansende-mails,sharefilesandsharefilesatwill.Browsetheweb.
(5)Warehousingmanagement:Forgeneralwarehousingpersonnel,throughtheapplicationofwirelessnetwork,thelatestdatacanbeinputintothecomputerwarehousingsystemimmediately.
(6)Containerterminal:Thebridgecranetruckofthegeneralcontainerterminalcantransmitreal-timeinformationbacktotheofficewhenthecontainersaremobilizedtofacilitatetheprogressofrelatedoperations.
(7)Surveillancesystem:Generallylocatedinaremoteplacewherethesiteneedstobemonitored.Duetothedifficultyofwiring,theremoteimagecanbetransmittedbacktothemaincontrolstationthroughthewirelessnetwork.
(8)Exhibitionvenues:suchasgeneralelectronicsexhibitionsandcomputerexhibitions.Duetotheextremelyhighnetworkrequirementsandthewiringwillmakethevenueappearmessy,itwouldbebetterifyoucanuseawirelessnetworkchoose.