Provider(互联网服务供应商).ppt

S3ComputerLiteracy InternetTechnology ConnectingtotheInternet HardwareRequirement MODEM56KorBroadbandMOdulationandDEModulationTelephoneLine ConnectingtotheInternet ISP ISP InternetServiceProvider 互聯網服務供應商 WhathasISPdoneforyou Itsendsandreceivesdataforyou ItprovidesaconnectionbetweenyouandtheotheroftheInternet Asshownintheanimationbelow thedataisinfacthandledbyanumberofISP AnimationforconnectiontotheInternet IsISPrunningtheInternet NosingleorganizationrunstheInternet Itisalargenetworkofnetworks Thesenetworksarelinkedbyhigh speedcommunicationchannelscalledbackbones EachInternetcomputer calledahost isindependent ConnectingtotheInternet TypeofAccess Dial upAccess 撥號上網 ItneedsatelephonelineMODEMUserdialsatelephonenumbergivenbytheISPtoconnecttotheserveroftheISP ausernameandpasswordtoauthenticatetheuser UsercanaccesshostsontheInternetDatatransferratemaximumof56Kbps ConnectingtotheInternet TypeofAccess BroadbandAccessItsspeedismeasuredinMbps i e Megabitpersecond Unlikedial upaccess itrequiresanetworkcard LANcardbutnomodemrequired BroadbandAccess ADSL ADSLatechnologyfortransmittingdigitalinformationatahighbandwidthonexistingphonelinestohomesandbusinesses ISPadoptingthistechnologyinHK Netvigator 網上行 GettotheInternet PPPoESomebroadbandInternetserviceproviders ISPs identifyyourcomputerontheirnetworksusingPointtoPointProtocoloverEthernet PPPoE IfyourISPrequiresyoutosupplyanameandpasswordtoaccesstheInternet itmostlikelyusesthisprotocol 議定 BroadbandAccess ADSL ADSL AsymmetricDigitalSubscriberLine Asymmetric 不對稱 betweendownloadspeedisfaster DownloadSpeed 1 5Mbpsto8MbpsUploadSpeed 16Kbpsto640KbpsComponents Networkcard ADSLMODEM TelephoneLine BroadbandAccess CableTVNetwork CableTVNetworkACableMODEMisusedtoenablesusertoconnectthePCtoalocalcableTVlineandreceivedataatabout10Mbps ISPadoptingthistechnologyinHK iCable 有線寬頻 BroadbandAccess CableTVNetwork CableTVNetworkDownloadanduploadspeedarethesame butthebandwidth 10Mbps issharedamongusersatthesamelocation e g thesamebuilding Hardwareused NetworkCard CableMODEM BroadbandvsDial upAccess Fasterconnectionspeed upto1 5Mbpsto10Mbps Nodialingrequired Simultaneoususeofdataandvoiceconnectionsie unlikedial upaccess usercantalkonthephonewhilesurfingtheInternet HowcanweshareInternetaccessinaLANtoaBroadband Arouter 路由器 isneededtoconnectaLANtotheInternet ItwillsharethebroadbandaccessfromoneInternetaccountamongallusersintheLAN CommunicationProtocol TCP IP TCP IPcommunicationprotocoloftheInternetsetofrulesusedinmessagetransmissionontheIputersneedtousethesameprotocoliftheyneedtocommunicate TCPandIP AdvantagesofTCP IP Ifwesendthewholefilewithoutbreakingitintopackets thewholemessagethenhastobere sentifthefullmessagefailstoreachitsdestinationifitisbrokendownintopackets thenonlythepacketthatfailtobesentareresent PacketAnimation AdvantagesofTCP IP Transmissionofdataisnotaffectedbythefailureofanypath therearemorethanonepath Packetsofdatacanberoutedaroundtheproblem theloadofthelineisevenlydistributed AslongastheoperatingsystemsupportsTCP IP thecomputerscancommunicatethroughLANandInternet TCPAnimation IPAddress Itidentifieseveryhost computer inanynetwork WhenapacketistransmittedovertheInternet itmustcarrytheaddressesofthesenderandreceivercomputerssothattherouterscanchoosethebestpath IPAddress Format TheIPaddresssystemcurrentlyusingiscalledtheIPv4addressingsystem QuestionregardingIPAddress Whatistherangeoftheeachsetofnumbers AseachcomputerintheInternethasauniqueIPaddress howmanycomputercanberepresentedintheInternet WhatcanwedoifthenumberofIPaddressesisnotenough RealIPandVirtualIP ImagineiftherearenotenoughIPaddressesinanetwork whatcanwedo ThesolutionistouseVirtualIP HowVirtualIPworks SomeoftheIPaddressesarereservedforprivatenetwork ie LAN E g 10 X X Xor192 168 X XTherouterwillnotroutetheseIPstotheInternet ie itwillroutethedatasendingtotheseIPsinsidetheLAN StaticIPandDynamicIP StaticIPIPaddressesthatarefixedeverytimewhentheuserconnecttotheInternet DynamicIPIPaddressesthatchangeseverytimetheuserconnecttotheInternet DomainNameSystem DNS Atthecommandwindow typeinthecommand hk whatdidyoufind Why Toconnecttoaspecificcomputer weneedtoknowitsIPaddress ConnecttotheYahoo webpage weneedtoknowitsaddress ie typehttp 68 142 226 41intheInternetbrowser ItisinconvenienttorememberthemeaninglessIPaddress DNSServer DNSServerresponsiblefortranslatingtheaddressintothecorrespondingIPaddress T WebServer WebServerisacomputerthatdeliversWebpages AcomputercanbecomeawebserverbyinstallingWebServerProgramlikeApacheandIIS InternetInformationServer WebBrowser AsoftwareapplicationusedtodisplayWebpages TwomostpopularbrowsersareNetscapeNavigatorandMicrosoftInternetExplorer IE Plug in 外掛程式 Thebrowsercannotplayallformatofaudioorvideofiles soaplug inprogramisneededtoaddsupporttothesetypesoffiles Casestudies Ifthehosts PCs cancommunicatewellintheLANbuttheyhavedifficultiestogettotheInternet whatwouldbetheproblem Ifyouareateacheran