公务员考试行测真题答案及解析ppt课件.ppt

概述 第1章 计算机网络的应用 商业应用家庭应用移动用户社会问题 网络的商业应用 1 带有两台客户机和一台服务器的网络 网络的商业应用 2 客户 服务器模型的请求和应答模式 家庭应用 访问远程信息个人之间的通信交互式娱乐电子商务 家庭应用 2 在对等系统中没有固定的客户和服务器 家庭应用 3 电子商务的一些形式 移动网络用户 无线网络和移动用户的组合 网络硬件 局域网络 LocalAreaNetworks 城域网 MetropolitanAreaNetworks 广域网 WideAreaNetworks 无线网络 WirelessNetworks 家庭网络 HomeNetworks 互联网 Internetworks 传输技术 广播链接 Broadcastlinks 点到点链接 Point to pointlinks 发送者和接收者的对应关系 或编址方式 单播 unicast 1对1 1个站点发送 1个站点接收 多播 multicast 1对多 1个站点发送 多个站点接收 广播 broadcast 1对所有 1个站点发送 所有站点接收 Classificationofinterconnectedprocessorsbyscale 网络分类 LocalAreaNetworks Twobroadcastnetworks a Bus 802 3 b Ring 802 5 FDDI MetropolitanAreaNetworks AmetropolitanareanetworkbasedoncableTV WideAreaNetworks RelationbetweenhostsonLANsandthesubnet 存储 转发 store and forward 分组交换 packet switched 路由算法 routingalgorithm WideAreaNetworks 2 Astreamofpacketsfromsendertoreceiver WirelessNetworks Categoriesofwirelessnetworks SysteminterconnectionWirelessLANs 802 11WirelessWANs 802 16 WirelessNetworks 2 a Bluetoothconfiguration b WirelessLAN WirelessNetworks 3 a Individualmobilecomputers b AflyingLAN HomeNetworkCategories Computers desktopPC PDA sharedperipheralsEntertainment TV DVD VCR camera stereo MP3 Telecomm telephone cellphone intercom fax Appliances microwave fridge clock furnace airco Telemetry utilitymeter burglaralarm babycam NetworkSoftware ProtocolHierarchiesDesignIssuesfortheLayersConnection OrientedandConnectionlessServicesServicePrimitivesTheRelationshipofServicestoProtocols NetworkSoftware协议层次 ProtocolHierarchies Layers protocols andinterfaces peerentity 协议层次 ProtocolHierarchies 2 Thephilosopher translator secretaryarchitecture 协议层次ProtocolHierarchies 3 支持第5层虚拟通信的信息流例子 协议栈 protocolstack 各层的设计问题 编址机制 Addressing 差错检测 ErrorDetection 差错控制 ErrorControl 流控制 FlowControl 多路复用 Multiplexing 路由选择 Routing 路由 route 面向连接和无连接服务Connection OrientedandConnectionlessServices 6种类型的服务 有连接无连接 有确认无确认 服务原语ServicePrimitives 5个服务原语实现简单的面向连接的服务 请求 Request 指示 Indication 响应 Response 确认 Confirm ServicePrimitives 2 Packetssentinasimpleclient serverinteractiononaconnection orientednetwork ServicestoProtocolsRelationship 服务与协议之间的关系 SDU PDU SAP PCI ICI ReferenceModels TheOSIReferenceModelTheTCP IPReferenceModelAComparisonofOSIandTCP IPACritiqueoftheOSIModelandProtocolsACritiqueoftheTCP IPReferenceModel ReferenceModels TheOSIreferencemodel ReferenceModels 2 TheTCP IPreferencemodel ReferenceModels 3 ProtocolsandnetworksintheTCP IPmodelinitially ComparingOSIandTCP IPModels ConceptscentraltotheOSImodelServicesInterfacesProtocols ACritiqueoftheOSIModelandProtocols WhyOSIdidnottakeovertheworldBadtimingBadtechnologyBadimplementationsBadpolitics BadTiming Theapocalypseofthetwoelephants ACritiqueoftheTCP IPReferenceModel Problems Service interface andprotocolnotdistinguishedNotageneralmodelHost to network layer notreallyalayerNomentionofphysicalanddatalinklayersMinorprotocolsdeeplyentrenched hardtoreplace HybridModel Thehybridreferencemodeltobeusedinthisbook ExampleNetworks TheInternetConnection OrientedNetworks X 25 FrameRelay andATMEthernetWirelessLANs 802 11 TheARPANET a Structureofthetelephonesystem b Baran sproposeddistributedswitchingsystem TheARPANET 2 TheoriginalARPANETdesign TheARPANET 3 GrowthoftheARPANET a December1969 b July1970 c March1971 d April1972 e September1972 NSFNET TheNSFNETbackbonein1988 InternetUsage Traditionalapplications 1970 1990 E mailNewsRemotelogin ArchitectureoftheInternet OverviewoftheInternet ATMVirtualCircuits Avirtualcircuit ATMVirtualCircuits 2 AnATMcell TheATMReferenceModel TheATMreferencemodel TheATMReferenceModel 2 TheATMlayersandsublayersandtheirfunctions Ethernet ArchitectureoftheoriginalEthernet WirelessLANs a Wirelessnetworkingwithabasestation b Adhocnetworking WirelessLANs 2 Therangeofasingleradiomaynotcovertheentiresystem WirelessLANs 3 Amulticell802 11network NetworkStandardization Who sWhointheTelecommunicationsWorldWho sWhointheInternationalStandardsWorldWho sWhointheInternetStandardsWorld ITU MainsectorsRadiocommunicationsTelecommunicationsStandardizationDevelopmentClassesofMembersNationalgovernmentsSectormembersAssociatemembers