高级网络技术-upper_layers(思科教材)

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1、UpperLayers(上层)Objectives（目标）RolesoftheTransportLayer（传输层的角色）TheTCPProtocol–CommunicatingwithReliability（TCP协议-可靠传输）MostusedApplicationLayerProtocols（常用应用层协议）ARealCase（实例）RolesoftheTransportLayerTwoDifferentTransportServicesTCPandUDPTCPConnection-ori

2、ented(面向连接)Reliabledelivery(可靠传输)Flowcontrol(流控)ApplicationsthatuseTCP:WebBrowsers;E-mailFileTransfersUDPSimpleConnectionless(无连接)Lowoverhead(低开销)Besteffort(尽力而为)ApplicationsthatuseUDP:DomainNameSystem(DNS);VideoStreaming;VoiceoverIP(VoIP)PortAddress

3、ingUsedforIdentifyingtheConversationsPortAddressingTypesofportnumbersPortAddressingnetstatCommandTheTCPProtocol–CommunicatingwithReliabilityTCP–MakingConversationsReliableTCPsegment(分割)TCPServerProcessTCPConnectionEstablishment(确定)andTermination（终止）E

4、stablishmentofTCPsessionsTCPConnectionEstablishmentandTerminationTerminationofTCPsessionsApplicationLayerProtocolsandServicesTCP/IPapplicationlayerprotocolsfitroughlyintotheframeworkofthetopthreelayersoftheOSImodel:Application,PresentationandSessionl

5、ayers.OSIandTCP/IPModelComparisonMostWidely-knownTCP/IPApplicationLayerProtocolsTheClient-SeverModelIntheclient/servermodel,thedevicerequestingtheinformationiscalledaclientandthedevicerespondingtotherequestiscalledaserver.Domainnameswerecreatedtoconv

6、ert（转换）thenumeric（数字的）addressintoasimple,recognizablename.DNSServicesandProtocolDNSServicesandProtocolnslookupcommandDNSServicesandProtocolTheDNSserverstoresdifferenttypesofresourcerecordsusedtoresolvenames.Theserecordscontainthename,address,andtypeo

7、frecord.DNSServicesandProtocolAhierarchyofDNSserverscontainstheresourcerecordsthatmatchnameswithaddresses.WWWServiceandHTTPEntering‘http://www.cisco.com’intheaddressbarofawebbrowsergeneratestheHTTP‘GET’Message.WWWServiceandHTTPInresponsetotherequest,

8、theHTTPserverreturnscodeforawebpage.WWWServiceandHTTPThebrowserinterpretstheHTMLcodeanddisplaysawebpage.E-mailServicesandSMTP/POPProtocolsClientssende-mailstoaserverusingSMTPandreceivee-mailsusingPOP3.E-mailServicesandSMTP/POPProtocolsE-mailServer–MT