F新版CCNA培训教材ch01

1NetworkingTechnologiesCERTIFICATIONOBJECTIVES1.01Networks1.02Topologies1.03NetworkTypes✓Two-MinuteDrillQ&ASelfTestCertPrs8/CCNACiscoCertifiedNetworkAssociateStudyGuide/Deal/222934-9/Chapter1BlindFolio1:1D:\omh\CertPrs8\934-9\ch01.vpMonday,August04,200310:00:42AMColorprofile:GenericCMYKprinterprofileCompositeDefaultscreenThischapteroffersabriefintroductiontonetworkingandsomebasicnetworkingtermsandconcepts.Thismaterialshouldbeareviewofmanyalreadyknownconcepts.Youshouldbefamiliarwiththevariousnetworkingtopologiesusedinnetworks,aswellasdifferenttypesofnetworks,suchaslocalareanetworks(LANs)andwideareanetworks(WANs).CERTIFICATIONOBJECTIVE1.01NetworksAnetworkisbasicallyallofthecomponents(hardwareandsoftware)involvedinconnectingcomputersacrosssmallandlargedistances.Networksareusedtoprovideeasyaccesstoinformation,thusincreasingproductivityforusers.Thissectioncoverssomeofthecomponentsinvolvedwithnetworking,aswellasthebasictypesoftopologiesusedtoconnectnetworkingdevices,includingcomputers.ComponentsOneofthemaincomponentsofnetworkingisapplications,whichenableuserstoperformvarioustasks.Manyapplicationsarenetwork-aware.Theseapplicationsallowyoutoaccessanduseresourcesthatarenotlocatedonyourlocalcomputer.Someofthemorecommonnetworkingapplicationsincludee-mail(sendingmailelectronically),FTP(transferringfiles),and(providingagraphicalrepresentationtoinformation).Thenumberofnetworkingapplicationsrangesinthethousands,butthoselistedarethemostcommonlyused.Tobuildanetwork,youneedthreetypesofdevicesorcomponents:computers,networkingdevices,andcabling.Computers—devicessuchasPCsandfileserversrunningMicrosoftWindows,MacintoshOS,Unix(includingLinux),orotheroperatingsystems—areresponsibleforprovidingapplicationstotheusers.Networkingdevices—suchashubs,bridges,switches,routers,firewalls,modems,NT1s(anISDNnetworkterminationdevice),andchannelserviceunits/dataserviceunits(CSU/DSUs)—areresponsibleformovinginformationbetweencomputers..Cabling,suchascopperorfibercabling,isneededtoconnectthecomputersandnetworkingdevicessothatinformationcanbesharedbetweencomponents.Wirelesscommunicationalsofallsinthiscategory.2Chapter1:NetworkingTechnologiesCertPrs8/CCNACiscoCertifiedNetworkAssociateStudyGuide/Deal/222934-9/Chapter1D:\omh\CertPrs8\934-9\ch01.vpMonday,August04,200310:00:42AMColorprofile:GenericCMYKprinterprofileCompositeDefaultscreenLocationsNetworkcomponentscanbelocatedinvariouslocations.Table1-1showssomecommontermsusedtodescribethelocationofnetworkcomponents.CERTIFICATIONOBJECTIVE1.02TopologiesWhenyouarecablingupyourcomputersandnetworkingdevices,varioustypesoftopologiescanbeused.Atopologydefineshowthedevicesareconnected.Figure1-1showsexamplesoftopologiesthatdifferentmediatypesuse.Apoint-to-pointtopologyhasasingleconnectionbetweentwodevices.Inthistopology,twodevicescandirectlycommunicatewithoutinterferencefromotherdevices.Thesetypesofconnectionsarenotcommonwhenmanydevicesneedtobeconnectedtogether.Anexampleofapoint-to-pointtopologyiswhenyouconnecttworoutersacrossadedicatedWANcircuit.Inastartopology,acentraldevicehasmanypoint-to-pointconnectionstootherdevices.Startopologiesareusedinenvironmentswheremanydevicesneedtobeconnected.Anexampleofamediatypethatusesastartopologyis10BaseTEthernet.Whenconnectingdevicestogether,youconnectyourcomputerstoahuborswitch(thecenterofthestar).Anextendedstartopologyisbasicallymultiplestartopologiesinterconnected.Abustopologyusesasingleconnectionorwiretoconnectalldevices.Certainmediatypes,like10Base5and10Base2Ethernet,useabustopology.Typically,specialTopologies3CertPrs8/CCNACiscoCertifiedNetworkAssociateStudyGuide/Deal/222934-9/Chapter1TermDefinitionSmalloffice/homeoffice(SOHO)Usersworkingfromahomeorsmalloffice(ahandfulofpeople)BranchofficeAsmallgroupofusersconnectedinasmallarea,calledaLAN,geographicallyseparatedfromacorporateofficeMobileusersUserswhocanconnecttoanetworkfromanylocation,LANorWANCorporateofficeThelocationwheremostusersinanorganizationandtheirresourcesarelocatedTABLE1-1NetworkingLocationsD:\omh\CertPrs8\934-9\ch01.vpMonday,August04,200310:00:43AMColorprofile:GenericCMYKprinterprofileCompositeDefaultscreentypesofconnectorsortransceiversareusedtoconnectthecablesinordertoprovidethebustopology.In10Base2,forexample,eachdeviceconnectstoasinglestrandofcoaxialcableviaavampiretap.Thisdevicetapsintothesinglestrandofcoaxialcableandprovidesthephysicalconnectionfromanetworkingdevicetothesinglestrandofcable.Inaringtopology,deviceoneconnectstodevicetwo,devicetwoconnectstodevicethree,andsoontothelastdevice,whichconnectsbacktodeviceone.Ringtopologiescanbeimplementedwithasingleringoradualring.Dualringsaretypicallyusedwhenyouneedredundancy.Forexample,ifoneofthedevicesfailsinthering,theringcanwrapitself,asshowninFigure1-2,toprovideasingle,functional,ring.FiberDistributedDataInterface(FDDI)isanexampleofamediatechnologythatusesdualringstoconnectcomputerdevices.4Chapter1:NetworkingTechnologiesCertPrs8/CCNACiscoCertifiedNetworkAssociateStudyGuide/Deal/222934-9/Chapter1FIGURE1-1NetworktopologiesD:\omh\CertPrs8\934-9\ch01.vpMonday