Discovery-Routing-Switching-Chapter-1-EN（思科网络技术学院CCNA4.0 官方资料-CCNA Discovery- CAC建议版Discovery- 英文版-D3-Routing-Switching-EN）

NetworkingintheEnterpriseIntroducingRoutingandSwitchingintheEnterprise–Chapter1ObjectivesDescribethelogicalarchitectureandcomponentsofanenterprisenetworkExplainthetypesofapplicationsandtrafficflowspresentonanenterprisenetworkExaminehowenterprisesintegrateremoteworkersintotheirnetworks-Definetheroleandimportanceofatelecommuter-DescribethefunctionandimportanceofVPNsContextIndex1.1DescribingtheEnterpriseNetwork1.2IdentifyingEnterpriseApplications1.3SupportingRemoteWorkers1.1DescribingtheEnterpriseNetwork1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-Asmallsinglelocationcompany.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-ThecompanyIncreasesitsnumberofemployees.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-Thecompanygrowstomultiplelocationsinthesamecity.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-Theenterprisegrowstomultiplecities.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-Theenterprisehiresteleworkers.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-Theenterpriseexpandstoothercountries.1.1.1SupportingtheBusinessEnterpriseAnexampleofthegrowthofabusinessintoanenterprise.-TheenterprisecentralizesnetworkmanagementinaNetworkOperationCenter(NOC).1.1.1SupportingtheBusinessEnterpriseNetworkinfrastructure99.999%uptimeHigh-endequipmentFail-overcapabilitiesRedundancyUsingthethree-layer

hierarchicaldesignmodelhelpsorganizethenetwork.1.1.2TrafficFlowinEnterpriseNetworkTheCiscoEnterpriseArchitecturesdividesthenetworkintofunctionalcomponents:

EnterpriseCampus:Consistsofthecampusinfrastructurewithserverfarmsandnetworkmanagement.

EnterpriseEdge:ConsistsoftheInternet,VPN,andWANmodulesconnectingtheenterprisewiththeserviceprovider'snetwork.

ServiceProviderEdge:ProvidesInternet,PublicSwitchedTelephoneNetwork(PSTN),andWANservices.1.1.2TrafficFlowinEnterpriseNetworkCiscoEnterpriseArchitectures1.1.2TrafficFlowinEnterpriseNetworkAwell-designednetworknotonlycontrolstrafficbutalsolimitsthesizeoffailuredomains.-Afailuredomainistheareaofanetworkimpactedwhenakeydeviceorserviceexperiencesproblems.Theuseofredundantlinksandreliableenterprise-classequipmentminimizethechanceofdisruptioninanetwork.1.1.2TrafficFlowinEnterpriseNetworkEnterprisenetworksincorporatebothtraditionalLANandWANtechnologies.Inatypicalenterprisenetwork,multiplelocalnetworksatasinglecampusinterconnectateithertheDistributionLayerortheCoreLayertoformaLAN.

TheselocalLANsinterconnectwithothersiteswhicharemoregeographicallydispersedtoformaWAN.1.1.3EnterpriseLANsandWANFeaturesofaLAN:-Theorganizationhastheresponsibilityofinstallingandmanagingtheinfrastructure.-Ethernetisthemostcommontechnologyused.-ThefocusofthenetworkisintheAccessandDistributionLayers.-TheLANconnectsusers,providessupportforlocalizedapplicationsandserverfarms.-Connecteddevicesareusuallyinthesamelocalarea,suchasabuildingoracampus.1.1.3EnterpriseLANsandWANFeaturesofaWAN:-Connectedsitesareusuallygeographicallydispersed.-ConnectivitytotheWANrequiresadevicesuchasamodemorCSU/DSUtoputthedatainaformacceptabletothenetworkoftheserviceprovider.-ServicesareprovidedbyanISP.WANservicesincludeT1/T3,E1/E3,DSL,Cable,FrameRelay,andATM.-TheISPhastheresponsibilityofinstallingandmanagingtheinfrastructure.-TheedgedevicesmodifytheEthernetencapsulationtoaserialWANencapsulation.1.1.3EnterpriseLANsandWAN1.1.4IntranetsandExtranetsIntranet-Provideaccesstolocalandremoteemployees-Privatenetwork-ControlledbyfirewallsExtranet-Privilegedaccessforbusinesspartners-Privatenetwork-Controlledaccess1.1.4IntranetsandExtranets1.2IdentifyingEnterpriseApplications1.2.1TrafficFlowPatternsAproperlydesignedenterprisenetworkhasdefinedandpredictabletrafficflowpatterns.Differenttrafficflows:-LAN1.2.1TrafficFlowPatternsAproperlydesignedenterprisenetworkhasdefinedandpredictabletrafficflowpatterns.Differenttrafficflows:-WAN1.2.1TrafficFlowPatternsAproperlydesignedenterprisenetworkhasdefinedandpredictabletrafficflowpatterns.Differenttrafficflows:-External1.2.2ApplicationandTrafficonanEnterpriseNetworkNewtechnologysupportsaconvergednetwork,wherevoice,video,anddataflowacrossthesamemedium.Thisconvergencepresentsmanydesignandbandwidthmanagementchallenges.Todeterminetrafficflowpatterns,itisimportantto:Capturetrafficduringpeakutilizationtimestogetagoodrepresentationofthedifferenttraffictypes.Performthecaptureondifferentnetworksegments,becausesometrafficwillbelocaltoaparticularsegment.1.2.3NetworkTrafficPrioritizationNotalltypesofnetworktraffichavethesamerequirementsorbehaveinthesamemanner.DataTrafficMostnetworkapplicationsutilizedatatraffic.DatatrafficusuallyemploysTransmissionControlProtocol(TCP).VoiceandVideoTrafficVoiceandvideoapplicationsrequireanuninterruptedstreamofdatatoensurehighqualityconversationsandimages.VoiceandvideoapplicationsemployUserDatagramProtocol(UDP)insteadofTCP.SinceUDPdoesnothavemechanismsforretransmittinglostpackets,itminimizesdelays.1.2.3NetworkTrafficPrioritizationItisimportanttoreducetheimpactofdelay,latency,andjitterontime-sensitivetraffic.QualityofService(QoS)isaprocessusedtoguaranteeaspecifieddataflow.QoSmechanismssorttrafficintoqueues,basedonpriority.1.2.3NetworkTrafficPrioritizationTrafficbeingprioritized1.2.3NetworkTrafficPrioritizationTrafficbeingprioritized1.2.3NetworkTrafficPrioritizationTrafficbeingprioritized1.2.3NetworkTrafficPrioritizationTrafficbeingprioritized1.3SupportingRemoteWorkers1.3.1TeleworkingTeleworking,alsoreferredtoastelecommutingande-commuting,allowsemployeestousetelecommunicationstechnologytoworkfromtheirhomesorotherremotelocations.1.3.1TeleworkingRemoteworkerapplications1.3.2VirtualPrivateNetworksEncryptalltraff