讲座：计算机网络历史,现状与未来

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1、计算机网络（Internet）历史，现状与未来舒炎泰2010计算机网络Transportationservice:moveobjectshorse,train,truck,airplane...Communicationnetwork:moveinformationbird,fire,telegraph,telephone,计算机网络…Internet…Communicationnetworkscanbeclassifiedbasedonthewayinwhichthenodesexchangeinformation:ATaxono

2、myofCommunicationNetworksCommunicationNetworkSwitchedCommunicationNetworkBroadcastCommunicationNetwork广播，电视Circuit-SwitchedCommunicationNetwork电话Packet-SwitchedCommunicationNetworkDatagramNetworkVirtualCircuitNetworkInternetCircuitSwitching（电路交换-电话）Anode(switch)in

3、acircuitswitchingnetworkincominglinksoutgoinglinksNodeTheexample通话在C到D(只经过一个本地交换机)的连接上进行通话在A到B(经过四个交换机)的连接上进行思考：电话交换对于计算机网络是否适合？效率/成本应用－实时((((交换机交换机交换机交换机用户线用户线中继线中继线BDCATiminginCircuitSwitchingpropagationdelaybetweenHost1andNode1propagationdelaybetweenHost2andNode1DAT

4、ACircuitEstablishmentDataTransmissionCircuitTerminationHost1Host2Node1Node2processingdelayatNode1Computernetworksself-development----packetswitching报文在发送端，先把较长的报文划分成较短的、固定长度的数据段。1101000110101010110101011100010011010010假定这个报文较长不便于传输Computernetworksself-development-

5、---packetswitching分组交换网以“分组”(也称包)作为数据传输单元依次把各分组发送到接收端（假定接收端在左边）。数据首部分组1数据首部分组2数据首部分组3Computernetworksdevelopment----packetswitching最后，在接收端把收到的数据恢复成为原来的报文。这里我们假定分组在传输过程中没有出现差错，在转发时也没有被丢弃。数据数据数据报文1101000110101010110101011100010011010010RouterCongestedRouterARouterBRoute

6、rCRouterDRouterEPacketSwitching-ExampleRouterFTimingofDatagramPacketSwitchingPacket3Packet3Packet1Packet2Packet1Packet2Packet1Packet2Packet3processingdelayofPacket1atNode2Host1Host2Node1Node2propagationdelaybetweenHost1andNode2transmissiontimeofPacket1atHost1PacketSwi

7、tching（分组/包交换）1961AnodeinapacketswitchingnetworkincominglinksoutgoinglinksNodeMemoryUseQueuingmodelstoDescribethebehaviorofqueuingsystemsEvaluatesystemperformanceModel:QueuingSystemQueuingSystemQueueServerCustomersResponseTimevs.ArrivalsInternet历史(1)Sep691stIMPinUCLA,O

8、ct692ndIMPinSRIInternet之父--L.Kleinrock19991969HistoryoftheInternet(2)HistoryoftheInternet(3)Sep691stIMPinUCLAOct692n