数据与计算机通信第19章

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1、WilliamStallingsDataandComputerCommunications7thEditionChapter19InternetworkProtocols内容19.1Multicasting19.2RoutingProtocols19.3IntegratedServicesArchitecture19.4DifferentiatedServices19.1MulticastingAddressesthatrefertogroupofhostsononeormorenetworksApplication

2、Multimedia“broadcast”TeleconferencingDatabaseDistributedcomputingRealtimeworkgroupsExampleConfigSupposethatmulticastserveronthenetworkN1istransmittingpacketstoamulticastaddressthatrepesentstheworkstationsindicatedonnetworksN3,N5,N6.SeeP617倒数第二段中间BroadcastandMult

3、ipleUnicastBroadcastacopyofpackettoeachnetworkRequires13copiesofpacketMultipleUnicastSendpacketonlytonetworksthathavehostsingroup11packetsTrueMulticastDetermineleastcostpathtoeachnetworkthathashostingroupGivesspanningtreeconfigurationcontainingnetworkswithgroupm

4、embersTransmitsinglepacketalongspanningtreeRoutersreplicatepacketsatbranchpointsofspanningtree8packetsrequiredMulticastExampleRequirementsforMulticasting(1)RoutermayhavetoforwardmorethanonecopyofpacketConventionneededtoidentifymulticastaddressesIPv4-ClassD-star

5、t1110IPv6-8bitprefix,all1,4bitflagsfield,4bitscopefield,112bitgroupidentifierNodesmusttranslatebetweenIPmulticastaddressesandlistofnetworkscontaininggroupmembersRoutermusttranslatebetweenIPmulticastaddressandnetworkmulticastaddressRequirementsforMulticasting(2)

6、MechanismrequiredforhoststojoinandleavemulticastgroupRoutersmustexchangeinfoWhichnetworksincludemembersofgivengroupSufficientinfotoworkoutshortestpathtoeachnetworkRoutingalgorithmtoworkoutshortestpathRoutersmustdetermineroutingpathsbasedonsourceanddestinationadd

7、ressesSpanningTreefromRouterCtoMulticastGroupInternetGroupManagementProtocol(IGMP)RFC3376HostandrouterexchangeofmulticastgroupinfoUsebroadcastLANtotransferinfoamongmultiplehostsandroutersPrincipleOperationsHostssendmessagestorouterstosubscribetoandunsubscribefro

8、mmulticastgroupGroupdefinedbymulticastaddressRouterscheckwhichmulticastgroupsofinteresttowhichhostsIGMPcurrentlyversion3IGMPv1HostscouldjoingroupRoutersusedtimertouns