第12章-多播路由協(xié)議要點(diǎn)課件

Chapter12MulticastingandMulticastRoutingProtocolsIntroductionMulticastaddressesandIGMPMulticastroutingMulticastroutingprotocolMBONEyn@112.1IntroductionIPUnicasting，IP單播通信OnesourceOnedestinationintheInternet

unicast

unicastaddress addressIPMulticasting，IP多播通信OnesourceAgroupofdestinationsintheInternet

unicast multicastaddress addressIPBroadcasting，IP廣播通信OnesourceAllofdestinationsinoneIPnetwork

unicast broadcastaddress addressyn@2DataLinkLayerPhysicalmulticastsupportMostLANs

supportphysicalmulticastaddressingMappingIPmulticastaddressestophysicalmulticastaddressesNophysicalmulticastsupportMostWANs

DONOTsupportphysicalmulticastaddressingUsingtunneling（隧道技術(shù)）toencapsulatethemulticastIPpacketinaunicastIPpacketOrbeencapsulatedaslinklayerbroadcastyn@3Multicastingvs.MultipleUnicastingLessbandwidthLessloadofsourceLessdelayMoreefficientyn@4MulticastApplicationsAccesstodistributeddatabase訪問(wèn)分布式數(shù)據(jù)庫(kù)Informationdissemination信息傳播DisseminationofNews傳播新聞Teleconferencing電視會(huì)議Distancelearning遠(yuǎn)程學(xué)習(xí)yn@512.2MulticastAddressandIGMPMulticastaddressFunction:defineahostgroupIPmulticastaddressesMACmulticastaddressesMappingclassDtoEthernetMACaddressIGMPInternetGroupManagementProtocol網(wǎng)際組管理協(xié)議yn@612.2.1IPMulticastAddressAllocation:IANA（RFC3171）ClassD:～55LocalNetworkControlBlock/24:～55NotbeforwardedbyrouterInternetworkControlBlock/24:～55MustbeforwardedthroughtheInternetAdministrativelyScopedAddressBlock/8:～55類似于私有IP單播地址（如/8）yn@712.2.2MACMulticastAddressIEEEMACaddressformatStandardGroupMACAddressesAllocation:IEEERegistrationAuthorityIEEE802.1DMACBridgeFilteredMACGroupAddresses01-80-C2-00-00-00～01-80-C2-00-00-0FStandardMACGroupAddresses01-80-C2-00-00-10～01-80-C2-FF-FF-FFOthers－h(huán)ttp:///regauthIP-mappedEthernetMACgroupaddresses01-00-5E-xx-xx-xxxxxxxxxxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxbitsyn@812.2.3MappingClassDtoEthernetMACAddressExampleProblem:不明確的MAC地址IP多播地址:MAC多播地址＝25:1＝32:1例:0x0100.5E01.0101表示32個(gè)IP多播地址,,,,…01-00-5E-7F-00-011110MulticastID:28bitsLost5bitsPrefix:25bitsMulticastID:23bitsIPmulticastaddressMACaddressPrefixyn@912.2.4IGMPInternetGroupManagementProtocol網(wǎng)際組管理協(xié)議Version1:RFC1112Version2:RFC2236Version3:RFC3376,RFC4604FunctionUsedbetweenhostsandmulticastroutersonasinglephysicalnetworkHelpthemulticastrouterscreateandupdatealistofloyalmembersrelatedtoeachrouterinterfaceNotamulticastroutingprotocol,butinconjunctionwithamulticastroutingprotocoltosupportIPmulticastingyn@10IGMPOperationIGMPoperateslocallyJoiningagroupLeavingagroupMonitoringmembershipyn@1112.3MulticastRoutingObjectivesofmulticastingOptimalroutingMulticastforwardingyn@1212.3.1ObjectivesofMulticastingEverymemberofthegroupshouldreceiveone,andonlyonecopyofthemulticastpacketNonmembersmustnotreceiveacopyTheremustbenoloopsinrouting,thatis,apacketmustnotvisitaroutermorethanonceThepathtraveledfromthesourcetoeachdestinationmustbeoptimalyn@1312.3.2OptimalRouting:ShortestPathTreesShortestpathtreeinunicastroutingEachrouterhasarouting

tablethatdefinesashortestpathtopossibledestinationsRoot:eachrouteritselfLeaf:possibledestinationsShortestpathtreeinmulticastroutingEachinvolvedrouterneedstoconstructashortestpathtreeforeachgroupTwotypesoftrees:source-based,group-sharedyn@14ShortestPathTreeinUnicastRoutingyn@15Flooding，洪泛FloodingisrelatedtobothmulticastingandbroadcastingMethodForwardsapacketoutofallofitsinterfacesexcepttheonefromwhichthepacketcameFeatureProvidebroadcastingCreateloopsandtrafficjams:severalcopiesofthesamepacketarecirculatedyn@16ShortestPathTreeinMulticastRoutingSource-BasedTree源點(diǎn)基準(zhǔn)樹(shù)or有源樹(shù)EachcombinationofsourceandgrouphasasingletreeEx.:NgroupsandMsourcesNxMtreesNotation:(S,G)——S＝多播源IP地址，G＝多播組地址Group-SharedTree組共享樹(shù)or共享樹(shù)EachgroupsharesthesametreeSteinertree,rendezvous-pointtree（匯集點(diǎn)樹(shù)，RPT）Ex.:NgroupsNtreesNotation:(*,G)——*＝所有的多播源，G＝多播組地址yn@17Source-BasedTree主機(jī)A主機(jī)B主機(jī)CR1R2R4R6假設(shè)：A、B、C在多播組中

R1R5R3ABC(,)R5R3R1BCA(,)R3R5yn@18Discuss:(S,G)（S,G）：最短路徑樹(shù)（SPT）樹(shù)根：多播組G的信息源（S）在具體的多播路由協(xié)議中，S通常指源子網(wǎng)樹(shù)葉：多播組G的接收成員（S,G）是單向樹(shù)多播信息流只能沿樹(shù)的下行方向傳播典型的多播路由協(xié)議DVMRP：?jiǎn)尾-V路由選擇的擴(kuò)展MOSPF：?jiǎn)尾-S路由選擇的擴(kuò)展PIM-DM：根據(jù)需要使用單播路由選擇協(xié)議yn@19Group-SharedTree:RPT主機(jī)A主機(jī)B主機(jī)CR1R2R4R6R3R5主機(jī)D根主機(jī)E(*,)R5R2R4CR6R3BD假設(shè)：A、B、C、D、E在多播組中

R1AEyn@20BidirectionalRPT主機(jī)A主機(jī)B主機(jī)CR1R2R4R6假設(shè)：A、B、C、D、E在多播組中

R3R5主機(jī)D(*,)R5R2R1R4CAR6R3EB根主機(jī)ED上行下行yn@21UnidirectionalRPT主機(jī)A主機(jī)B主機(jī)CR1R2R4R6假設(shè)：A、B、C、D、E在多播組中

R3R5主機(jī)D(*,)R5R2R1R4CAR6R3EB根主機(jī)ED下行多播源如何將多播信息流送至根?yn@22UnidirectionalRPT

+Source-BasedTree主機(jī)A主機(jī)B主機(jī)CR1R2R4R6假設(shè)：A、B、C、D、E在多播組中

R3R5主機(jī)D根主機(jī)E(*,)R5R2R1R4CAR6R3EBDAR1R2R4(A,)yn@23

UnidirectionalRPT

+UnicastTunneling主機(jī)A主機(jī)B主機(jī)CR1R2R4R6假設(shè)：A、B、C、D、E在多播組中

R3R5主機(jī)D根主機(jī)E(*,)R5R2R1R4CAR6R3EBD單播隧道yn@24Discuss:RPTRPT:（*,G）樹(shù)根：多播組G的匯集點(diǎn)（RP）路由器靜態(tài)指定RP：管理員根據(jù)需要指定動(dòng)態(tài)選取RP：最高IP地址，RP哈希算法（RFC2362）樹(shù)葉：多播組G的接收成員多播組G的信息源S不一定在（*,G）上多播信息源S在RPT上：適合使用雙向RPT多播信息源S不在RPT上：適合使用單向RPT典型的多播路由協(xié)議CBT：雙向RPT（＋單播隧道：信息源不在RPT上）PIM-SM：?jiǎn)蜗騌PT＋有源樹(shù)——匯集點(diǎn)路由器的最短路徑樹(shù)yn@25有源樹(shù)vs.共享樹(shù)樹(shù)根與多播源有源樹(shù)的樹(shù)根就是多播源無(wú)需靜態(tài)指定或動(dòng)態(tài)選取，多播源一定在有源樹(shù)上共享樹(shù)的樹(shù)根不是多播源需靜態(tài)指定或動(dòng)態(tài)選取，多播源不一定在共享樹(shù)上對(duì)多播路由器的影響共享樹(shù)對(duì)多播路由器的資源消耗少于有源樹(shù)有源樹(shù)個(gè)數(shù)隨（多播源，多播組）的增加而增加共享樹(shù)個(gè)數(shù)隨多播組的增加而增加多播數(shù)據(jù)流的傳輸延遲共享樹(shù)的多播數(shù)據(jù)流的傳輸延遲大于有源樹(shù)有源樹(shù)是從多播源到所有組成員的最短路徑樹(shù)共享樹(shù)只是從匯集點(diǎn)到所有組成員的最短路徑樹(shù)yn@26Pruning,剪枝剪掉樹(shù)中沒(méi)有多播接收成員分支的過(guò)程，有時(shí)效性例：接收站A，組G源網(wǎng)絡(luò)S，組GR5R4R3R1R2R6R4R3R2SR1R5R6（S，G）R3SR1剪枝后的（S，G）yn@27Grafting,嫁接剪掉的分支上如果又出現(xiàn)了多播接收成員，則將其快速接回樹(shù)上的過(guò)程例：接收站A，組G源網(wǎng)絡(luò)S，組GR5R4R3R1R2R6R3SR1嫁接前的（S，G）接收站B，組GR4R3SR1R6嫁接后的（S，G）yn@28PruningandGraftingTocreateamulticastshortestpathtreethatsupportsdynamicmembershipchangesTomakemulticastingmoreefficientyn@2912.3.3MulticastForwardingUnicastforwardingUsethedestinationIPaddressintheIPpackettolookuptheunicastroutingtabletodecidewhetherandhowtoforwardMulticastforwardingReversepathforwarding:逆向路徑轉(zhuǎn)發(fā),RPFUsethesourceIPaddressintheIPpackettolookupthemulticastroutingtableortheunicastroutingtabletodecidewhethertoforwardOutgoinginterfacelist:輸出接口列表ConstructedbythemulticasttreetoperformtheforwardingMulticastforwardingcacheyn@30R1的路由表網(wǎng)絡(luò)接口/16/24S0/24E0RPFCheckExample1

源1的多播分組分組到達(dá)錯(cuò)誤接口丟棄S0E0S1S2R1S1PIM、CBT：?jiǎn)尾ヂ酚杀鞤VMRP：多播路由表yn@31R1的路由表網(wǎng)絡(luò)接口/16/24S0/24E0RPFCheckExample2

源1的多播分組分組到達(dá)正確接口按輸出接口表轉(zhuǎn)發(fā)S1S0E0S2R1S1yn@32MulticastForwardingCacheMulticastforwardingcacheentryMulticasttree,incominginterface:RPFcheckOutgoinginterfacelistExample:Ciscorouter

(*,),00:03:54/00:02:59,RP

Incominginterface:Serial0,RPFnbr

Outgoinginterfacelist:

Serial1,Forward/Sparse,00:01:43/00:02:11

Serial2,Forward/Sparse,00:03:54/00:02:06

(21/32,),00:00:25/00:02:53

Incominginterface:Serial0,RPFnbr

Outgoinginterfacelist:

Serial2,Forward/Sparse,00:00:25/00:02:35yn@3312.4MulticastRoutingProtocolMulticastroutingprotocolsSource-BasedTree(S,G)Group-SharedTree(*,G)MOSPFPIM-DMPIM-SMCBTDVMRPPIMDenseMode,DM密集模式協(xié)議SparseMode,SM稀疏模式協(xié)議LinkState鏈路狀態(tài)協(xié)議yn@34LS,DMandSMProtocolsLS（LinkState，鏈路狀態(tài)）協(xié)議通過(guò)擴(kuò)散多播鏈路狀態(tài)信息形成（S,G）DM（DenseMode，密集模式）協(xié)議PUSH原理：假設(shè)網(wǎng)絡(luò)中的每個(gè)子網(wǎng)內(nèi)至少有一個(gè)多播數(shù)據(jù)流的接收站類比：電臺(tái)廣播或電視廣播特性：（S,G），周期性的擴(kuò)散和剪枝SM（SparseMode，稀疏模式）協(xié)議PULL原理：假設(shè)網(wǎng)絡(luò)中初始沒(méi)有多播接收站，除非顯式加入類比：有線電視特性：（*,G），周期性的顯式加入和剪枝yn@35MOSPFMulticastOpenShortestPathFirst多播開(kāi)放最短路徑優(yōu)先，RFC1584，RFC1585AnenhancementofOSPFv2UsesIGMPtomonitormulticastgroupmembershipFloodsthegroup-membership-LSA(type6)throughouttheroutingdomainAseparateshortest-pathtreeisbuiltondemandforeach[sourcenetwork,multicastgroup]combinationFeatureL-S,IGP,(S,G),LSForwardingcacheentrylocalgroupdatabase–IGMPlinkstatedatabase–OSPFtype6LSAyn@36DVMRPDistanceVectorMulticastRoutingProtocol距離向量多播路由選擇協(xié)議，RFC1075CombinemanyfeaturesofRIPwiththetruncatedreversepathbroadcasting(TRPB,截?cái)喾聪蚵窂綇V播)algorithmUsesIGMPtoexchangeroutingmessagesSourcenetworkaddress,sourcenetworkmask,hopcountMaintainsamulticastroutingtabletokeeptrackofthereturnpathstothesourceofmulticastpacketsFeatureD-V,IGP,(S,G),DMForwardingcacheentryMulticastroutingtableyn@37PIM-DMProtocolIndependentMulticast–DenseMode協(xié)議無(wú)關(guān)多播－密集模式，RFC3973Usestheunderlyingunicastroutinginformationbaseoraseparatemulticast-capableroutinginformationbaseNotoexchangeroutingmessagesNomulticastroutingtableFeatureProtocolindependent(S,G),DMForwardingcacheentryPIMHello,Prune,andGraftmessages:build(S,G)Unicastroutingtable:performRP