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1、Chapter 12 Multicasting and Multicast Routing Protocolsn nIntroductionn nMulticast addresses and IGMPn nMulticast routingn nMulticast routing protocoln nMBONE1 112.1 Introductionn nIP IP UnicastingUnicasting，IPIP单播通信单播通信单播通信单播通信n nOne source One source One destination in the InternetOne destination
2、in the Internet unicastunicast unicastunicast address address addressaddressn nIP MulticastingIP Multicasting，IPIP多播通信多播通信多播通信多播通信n nOne source One source A group of destinations in the Internet A group of destinations in the Internet unicastunicastmulticastmulticast address address address addressn
3、 nIP BroadcastingIP Broadcasting，IPIP广播通信广播通信广播通信广播通信n nOne source One source A All of destinations in one IP networkll of destinations in one IP network unicastunicastbroadcastbroadcast address address 2 2Data Link Layern nPhysical multicast supportn nMost Most LANsLANs supportsupport physical mult
4、icast addressing physical multicast addressingn nMappingMapping IP multicast addresses to physical IP multicast addresses to physical multicast addressesmulticast addressesn nNo physical multicast supportn nMost Most WANsWANs DO NOTDO NOT support physical multicast support physical multicast address
5、ingaddressingn nUsing Using tunnelingtunneling（隧道技术）（隧道技术）（隧道技术）（隧道技术）to encapsulate the to encapsulate the multicast IP packet in a multicast IP packet in a unicastunicast IP packet IP packet n nOr be encapsulated as Or be encapsulated as link layer broadcastlink layer 3 3Multicasting vs.Multiple U
6、nicastingLess bandwidthLess load of sourceLess delayMore 4 4Multicast Applicationsn nAccess to distributed databaseAccess to distributed databasen n访问分布式数据库访问分布式数据库访问分布式数据库访问分布式数据库n nInformation disseminationInformation disseminationn n信息传播信息传播信息传播信息传播n nDissemination of NewsDissemination of Newsn n
7、传播新闻传播新闻传播新闻传播新闻n nTeleconferencingTeleconferencingn n电视会议电视会议电视会议电视会议n nDistance learningDistance learningn n远程学习远程学习远程学习远程学习5 512.2 Multicast Address and IGMPn nMulticast addressn nFunction:define a host groupFunction:define a host groupn nIP multicast addressesIP multicast addressesn nMAC multica
8、st addressesMAC multicast addressesn nMapping class D to Ethernet MAC addressMapping class D to Ethernet MAC addressn nIGMPn nInternet Group Management ProtocolInternet Group Management Protocoln n网际组管理协议网际组管理协议网际组管理协议网际组管理协议6 612.2.1 IP Multicast Addressn nAllocation:IANA（RFC 3171）n nClass D:224.0.
9、0.0Class D:224.0.0.0239.255.255.255239.255.255.255n nLocal Network Control BlockLocal Network Control Blockn n224.0.0.0/24:224.0.0.0224.0.0.0/24:224.0.0.0224.0.0.255224.0.0.255n nNot be forwarded by routerNot be forwarded by routern nInternetwork Control BlockInternetwork Control Blockn n224.0.1.0/2
10、4:224.0.1.0224.0.1.0/24:224.0.1.0224.0.1.255224.0.1.255n nMust be forwarded through the InternetMust be forwarded through the Internetn nAdministratively Scoped Address BlockAdministratively Scoped Address Blockn n239.0.0.0/8:239.0.0.0239.0.0.0/8:239.0.0.0239.255.255.255239.255.255.255n n类似于私有类似于私有类
11、似于私有类似于私有IPIP单播地址（如单播地址（如单播地址（如单播地址（如10.0.0.0/810.0.0.0/8）7 712.2.2 MAC Multicast Addressn nIEEE MAC address formatIEEE MAC address formatn nStandard Group MAC AddressesStandard Group MAC Addressesn nAllocation:IEEE Registration AuthorityAllocation:IEEE Registration Authorityn nIEEE 802.1D MAC Bridg
12、e Filtered MAC Group AddressesIEEE 802.1D MAC Bridge Filtered MAC Group Addressesn n01-80-C2-00-00-0001-80-C2-00-00-0001-80-C2-00-00-0F01-80-C2-00-00-0Fn nStandard MAC Group AddressesStandard MAC Group Addressesn n01-80-C2-00-00-1001-80-C2-00-00-1001-80-C2-FF-FF-FF01-80-C2-FF-FF-FFn nOthersOthershtt
13、p:/http:/standards.ieee.org/regauthstandards.ieee.org/regauthn nIP-mapped Ethernet MAC group addressesIP-mapped Ethernet MAC group addressesn n01-00-5E01-00-5E-xx-xx-xx-xx-xx-xxxxxxxxxxxxxxxxxxxx1 1 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 8 812.2.3 Mapping Class D to Ethe
14、rnet MAC Addressn nExampleExamplen nProblem:Problem:不明确的不明确的不明确的不明确的MACMAC地址地址地址地址n nIPIP多播地址多播地址多播地址多播地址:MAC:MAC多播地址多播地址多播地址多播地址2 25 5:1:132:132:1n n例例例例:0 x0100.5E01.0101:0 x0100.5E01.0101表示表示表示表示3232个个个个IPIP多播地址多播地址多播地址多播地址n n224.1.1.1,224.128.1.1,225.1.1.1,225.128.1.1,239.128.1.1224.1.1.1,224.12
15、8.1.1,225.1.1.1,225.128.1.1,239.128.1.1239.255.0.1239.255.0.101-00-5E-7F-00-0101-00-5E-7F-00-0111101110Multicast ID:28 bits Multicast ID:28 bits Lost 5 bitsLost 5 bitsPrefix:25 bitsPrefix:25 bitsMulticast ID:23 bits Multicast ID:23 bits IP multicast addressIP multicast addressMACMACaddressaddressPre
16、fixP9 912.2.4 IGMPn nInternet Group Management ProtocolInternet Group Management Protocoln n网际组管理协议网际组管理协议网际组管理协议网际组管理协议n nVersion 1:RFC 1112Version 1:RFC 1112n nVersion 2:RFC 2236Version 2:RFC 2236n nVersion 3:RFC 3376,RFC 4604Version 3:RFC 3376,RFC 4604n nFunctionFunctionn nUsed Used betweenbetwee
17、n hosts and multicast routers on a single hosts and multicast routers on a single physical networkphysical networkn nHelpHelp the multicast routers create and update a list of the multicast routers create and update a list of loyal members related to each router interfaceloyal members related to eac
18、h router interfacen nNotNot a multicast routing protocol,a multicast routing protocol,butbut in conjunction with a in conjunction with a multicast routing protocol to support IP multicastingmulticast routing protocol to support IP 1010IGMP Operationn nIGMP operates locallyn nJoining a groupJoining a
19、 groupn nLeaving a groupLeaving a groupn nMonitoring membershipMonitoring 111112.3 Multicast Routingn nObjectives of multicastingn nOptimal routingn nMulticast 121212.3.1 Objectives of Multicastingn nEvery member of the group should receive one,and only one copy of the multicast packetn nNonmembers
20、must not receive a copyn nThere must be no loops in routing,that is,a packet must not visit a router more than oncen nThe path traveled from the source to each destination must be 131312.3.2 Optimal Routing:Shortest Path Trees n nShortest path tree in unicast routingn nEach router has a Each router
21、has a routingrouting tabletable that defines a that defines a shortest pathshortest path to to possible destinationspossible destinationsn nRoot:Root:each each router itselfrouter itselfn nLeafLeaf:possible destinations:possible destinationsn nShortest path tree in multicast routingn nEach Each invo
22、lvedinvolved router needs to construct a router needs to construct a shortest shortest path treepath tree for for each groupeach groupn nTwo types of trees:source-based,group-sharedTwo types of trees:source-based,group-1414Shortest Path Tree in Unicast R1515Flooding，洪泛，洪泛n nFlooding is related to bo
23、th multicasting and broadcastingn nMethodn nForwards a packet out of all of its interfaces Forwards a packet out of all of its interfaces except the one from which the packet cameexcept the one from which the packet camen nFeaturen nProvide broadcastingProvide broadcastingn nCreate loops and traffic
24、 jams:several copies of Create loops and traffic jams:several copies of the same packet are circulatedthe same packet are 1616Shortest Path Tree in Multicast Routingn nSource-Based TreeSource-Based Treen n源点基准树源点基准树源点基准树源点基准树 or or 有源树有源树有源树有源树n nEach combination of source and group has a single tre
25、eEach combination of source and group has a single treen nEx.:N groups and M sources Ex.:N groups and M sources N x M trees N x M treesn nNotation:(S,G)SNotation:(S,G)S多播源多播源多播源多播源IPIP地址，地址，地址，地址，G G多播组地址多播组地址多播组地址多播组地址n nGroup-Shared TreeGroup-Shared Treen n组共享树组共享树组共享树组共享树 or or 共享树共享树共享树共享树n nEac
26、h group shares the same treeEach group shares the same treen nSteiner tree,rendezvous-point treeSteiner tree,rendezvous-point tree（汇集点树，（汇集点树，（汇集点树，（汇集点树，RPTRPT）n nEx.:N groups Ex.:N groups N trees N treesn nNotation:(*,G)*Notation:(*,G)*所有的多播源，所有的多播源，所有的多播源，所有的多播源，G G多播组地址多播组地址多播组地址多播组地址1717Source-
27、Based Tree主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3假设：假设：A、B、C在多播在多播组组224.1.1.1中中 R1R5R3ABC(192.1.1.1,224.1.1.1)(192.1.1.1,224.1.1.1)R5R3R1BCA(192.1.1.2,224.1.1.1)(192.1.1.2,224.1.1.1)R3R1818Discuss:(S,G)n n（S,G）：最短路径树（）：最短路径树（SPT）n n树根：多播组树根：多播组树根：多播组树根：多播组G G的信息源（的信息源（的信息源（的信息源（S S）n n在具体
28、的多播路由协议中，在具体的多播路由协议中，在具体的多播路由协议中，在具体的多播路由协议中，S S通常指源子网通常指源子网通常指源子网通常指源子网n n树叶：多播组树叶：多播组树叶：多播组树叶：多播组G G的接收成员的接收成员的接收成员的接收成员n n（S,G）是单向树）是单向树n n多播信息流只能沿树的下行方向传播多播信息流只能沿树的下行方向传播多播信息流只能沿树的下行方向传播多播信息流只能沿树的下行方向传播n n典型的多播路由协议典型的多播路由协议n nDVMRPDVMRP：单播：单播：单播：单播D-VD-V路由选择的扩展路由选择的扩展路由选择的扩展路由选择的扩展n nMOSPFMOSPF：
29、单播：单播：单播：单播L-SL-S路由选择的扩展路由选择的扩展路由选择的扩展路由选择的扩展n nPIM-DMPIM-DM：根据需要使用单播路由选择协议：根据需要使用单播路由选择协议：根据需要使用单播路由选择协议：根据需要使用单播路由选择协议1919Group-Shared Tree:RPT主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3R3R5主机主机D192.4.4.4根根根根主机主机E192.5.5.5(*,224.2.2.2)(*,224.2.2.2)R5R2R4CR6 R3BD假设：假设：A、B、C、D、E在在多播组多播组224.2.
30、2.2中中 R1AE2020 Bidirectional RPT主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3假设：假设：A、B、C、D、E在在多播组多播组224.2.2.2中中 R3R5主机主机D192.4.4.4(*,224.2.2.2)(*,224.2.2.2)R5R2R1R4CAR6 R3EB根根根根主机主机E192.5.5.5D上行上行上行上行下行下行下行下行2121 Unidirectional RPT主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3假设：假设：A、B、C、D、
31、E在在多播组多播组224.2.2.2中中 R3R5主机主机D192.4.4.4(*,224.2.2.2)(*,224.2.2.2)R5R2R1R4CAR6 R3EB根根根根主机主机E192.5.5.5D下行下行下行下行多播源如何多播源如何多播源如何多播源如何将多播信息将多播信息将多播信息将多播信息流送至根流送至根流送至根流送至根?2222 Unidirectional RPT+Source-Based Tree主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3假设：假设：A、B、C、D、E在在多播组多播组224.2.2.2中中 R3R5主机主机
32、D192.4.4.4根根根根主机主机E192.5.5.5(*,224.2.2.2)(*,224.2.2.2)R5R2R1R4CAR6 R3EBDAR1R2R4(A,224.2.2.2)(A,224.2.2.2)2323 Unidirectional RPT+Unicast Tunneling主机主机A主机主机B主机主机CR1R2R4R6192.1.1.1192.2.2.2192.3.3.3假设：假设：A、B、C、D、E在在多播组多播组224.2.2.2中中 R3R5主机主机D192.4.4.4根根根根主机主机E192.5.5.5(*,224.2.2.2)(*,224.2.2.2)R5R2R1R
33、4CAR6 R3EBD单播单播单播单播隧道隧道隧道隧道2424Discuss:RPTn nRPT:RPT:（*,G,G）n n树根：多播组树根：多播组树根：多播组树根：多播组G G的汇集点（的汇集点（的汇集点（的汇集点（RPRP）路由器）路由器）路由器）路由器n n静态指定静态指定静态指定静态指定RPRP：管理员根据需要指定：管理员根据需要指定：管理员根据需要指定：管理员根据需要指定n n动态选取动态选取动态选取动态选取RPRP：最高：最高：最高：最高IPIP地址，地址，地址，地址，RPRP哈希算法（哈希算法（哈希算法（哈希算法（RFC 2362RFC 2362）n n树叶：多播组树叶：多播组
34、树叶：多播组树叶：多播组G G的接收成员的接收成员的接收成员的接收成员n n多播组多播组多播组多播组G G的信息源的信息源的信息源的信息源S S不一定不一定不一定不一定在（在（在（在（*,G,G）上）上）上）上n n多播信息源多播信息源多播信息源多播信息源S S在在在在RPTRPT上：适合使用双向上：适合使用双向上：适合使用双向上：适合使用双向RPTRPTn n多播信息源多播信息源多播信息源多播信息源S S不在不在不在不在RPTRPT上：适合使用单向上：适合使用单向上：适合使用单向上：适合使用单向RPTRPTn n典型的多播路由协议典型的多播路由协议典型的多播路由协议典型的多播路由协议n nC
35、BTCBT：双向：双向：双向：双向RPTRPT（单播隧道：信息源不在（单播隧道：信息源不在（单播隧道：信息源不在（单播隧道：信息源不在RPTRPT上）上）上）上）n nPIM-SMPIM-SM：单向：单向：单向：单向RPTRPT有源树有源树有源树有源树 汇集点路由器的最短路径树汇集点路由器的最短路径树汇集点路由器的最短路径树汇集点路由器的最短路径树2525有源树有源树 vs.共享树共享树n n树根与多播源树根与多播源树根与多播源树根与多播源n n有源树的树根就是多播源有源树的树根就是多播源有源树的树根就是多播源有源树的树根就是多播源n n无需静态指定或动态选取，多播源一定在有源树上无需静态指定
36、或动态选取，多播源一定在有源树上无需静态指定或动态选取，多播源一定在有源树上无需静态指定或动态选取，多播源一定在有源树上n n共享树的树根不是多播源共享树的树根不是多播源共享树的树根不是多播源共享树的树根不是多播源n n需静态指定或动态选取，多播源不一定在共享树上需静态指定或动态选取，多播源不一定在共享树上需静态指定或动态选取，多播源不一定在共享树上需静态指定或动态选取，多播源不一定在共享树上n n对多播路由器的影响对多播路由器的影响对多播路由器的影响对多播路由器的影响n n共享树对多播路由器的资源消耗少于有源树共享树对多播路由器的资源消耗少于有源树共享树对多播路由器的资源消耗少于有源树共享树
37、对多播路由器的资源消耗少于有源树n n有源树个数随（多播源，多播组）的增加而增加有源树个数随（多播源，多播组）的增加而增加有源树个数随（多播源，多播组）的增加而增加有源树个数随（多播源，多播组）的增加而增加n n共享树个数随多播组的增加而增加共享树个数随多播组的增加而增加共享树个数随多播组的增加而增加共享树个数随多播组的增加而增加n n多播数据流的传输延迟多播数据流的传输延迟多播数据流的传输延迟多播数据流的传输延迟n n共享树的多播数据流的传输延迟大于有源树共享树的多播数据流的传输延迟大于有源树共享树的多播数据流的传输延迟大于有源树共享树的多播数据流的传输延迟大于有源树n n有源树是从多播源到
38、所有组成员的最短路径树有源树是从多播源到所有组成员的最短路径树有源树是从多播源到所有组成员的最短路径树有源树是从多播源到所有组成员的最短路径树n n共享树只是从汇集点到所有组成员的最短路径树共享树只是从汇集点到所有组成员的最短路径树共享树只是从汇集点到所有组成员的最短路径树共享树只是从汇集点到所有组成员的最短路径树2626Pruning,剪枝剪枝n n剪掉树中没有多播接收成员分支的过程，有时效性剪掉树中没有多播接收成员分支的过程，有时效性剪掉树中没有多播接收成员分支的过程，有时效性剪掉树中没有多播接收成员分支的过程，有时效性n n例：例：例：例：接收站接收站接收站接收站A A，组，组，组，组G
39、 G源网络源网络源网络源网络S S，组，组，组，组G GR5R5R4R4R3R3R1R1R2R2R6R6R4R4R3R3R2R2S S R1R1R5R5R6R6（S S，G G）R3R3S S R1R1剪枝后的（剪枝后的（剪枝后的（剪枝后的（S S，G G）2727Grafting,嫁接嫁接n n剪掉的分支上如果又出现了多播接收成员，则将其剪掉的分支上如果又出现了多播接收成员，则将其剪掉的分支上如果又出现了多播接收成员，则将其剪掉的分支上如果又出现了多播接收成员，则将其快速接回树上的过程快速接回树上的过程快速接回树上的过程快速接回树上的过程n n例：例：例：例：接收站接收站接收站接收站A A，
40、组，组，组，组G G源网络源网络源网络源网络S S，组，组，组，组G GR5R5R4R4R3R3R1R1R2R2R6R6R3R3S S R1R1嫁接前的嫁接前的嫁接前的嫁接前的（S S，G G）接收站接收站接收站接收站B B，组组组组G GR4R4R3R3S S R1R1R6R6嫁接后的嫁接后的嫁接后的嫁接后的（S S，G G）2828Pruning and Graftingn nTo create a multicast shortest path tree that supports dynamic membership changesn nTo make multicasting mor
41、e 292912.3.3 Multicast Forwardingn nUnicastUnicast forwarding forwardingn nUse the Use the destinationdestination IP address in the IP packet to lookup IP address in the IP packet to lookup the the unicastunicast routing table routing table to decide to decide whether and howwhether and how to to fo
42、rwardforwardn nMulticast forwardingMulticast forwardingn nReverse path forwarding:Reverse path forwarding:逆向路径转发逆向路径转发逆向路径转发逆向路径转发,RPF,RPFn nUse theUse the source source IP address in the IP packet to lookup the IP address in the IP packet to lookup the multicast routing tablemulticast routing table
43、 or the or the unicastunicast routing table routing table to decide to decide whetherwhether to forward to forwardn nOutgoing interface list:Outgoing interface list:输出接口列表输出接口列表输出接口列表输出接口列表n nConstructed by the multicast tree to Constructed by the multicast tree to performperform the forwarding the
44、forwarding Multicast forwarding cacheMulticast forwarding 3030R1R1的路由表的路由表的路由表的路由表网络网络网络网络接口接口接口接口151.10.0.0/16198.14.32.0/24S0204.1.16.0/24E0RPF Check Example 1 源源源源151.10.3.21151.10.3.21的多播分组的多播分组的多播分组的多播分组分组到分组到分组到分组到达错误达错误达错误达错误接口接口接口接口丢弃丢弃丢弃丢弃S0E0S1S2R1S1PIMPIM、CBTCBT：单播路由表：单播路由表：单播路由表：单播路由表DVM
45、RPDVMRP：多播路由表：多播路由表：多播路由表：多播路由表3131R1R1的路由表的路由表的路由表的路由表网络网络网络网络接口接口接口接口151.10.0.0/16198.14.32.0/24S0204.1.16.0/24E0RPF Check Example 2 源源源源151.10.3.21151.10.3.21的多播分组的多播分组的多播分组的多播分组分组到分组到分组到分组到达正确达正确达正确达正确接口接口接口接口按输按输按输按输出接口出接口出接口出接口表表表表转发转发转发转发S1S0E0S2R1S3232Multicast Forwarding Cachen nMulticast f
46、orwarding cache entryMulticast forwarding cache entryn nMulticast tree,incoming interface:RPF checkMulticast tree,incoming interface:RPF checkn nOutgoing interface listOutgoing interface listn nExample:Cisco routerExample:Cisco router(*,224.1.1.1)(*,224.1.1.1),00:03:54/00:02:59,RP 10.1.5.1,00:03:54/
47、00:02:59,RP 10.1.5.1 Incoming interface:Serial0Incoming interface:Serial0,RPF,RPF nbrnbr 10.1.5.1 10.1.5.1 Outgoing interface list:Outgoing interface list:Serial1Serial1,Forward/Sparse,00:01:43/00:02:11,Forward/Sparse,00:01:43/00:02:11 Serial2Serial2,Forward/Sparse,00:03:54/00:02:06,Forward/Sparse,0
48、0:03:54/00:02:06(171.68.37.121/32,224.1.1.1)(171.68.37.121/32,224.1.1.1),00:00:25/00:02:53,00:00:25/00:02:53 Incoming interface:Serial0Incoming interface:Serial0,RPF,RPF nbrnbr 10.1.5.1 10.1.5.1 Outgoing interface list:Outgoing interface list:Serial2Serial2,Forward/Sparse,00:00:25/00:02:35,Forward/S
49、parse,00:00:25/00:02:333312.4 Multicast Routing ProtocolMulticast routing protocolsSource-Based TreeSource-Based Tree(S,G)(S,G)Group-Shared TreeGroup-Shared Tree(*,G)(*,G)MOSPFMOSPFPIM-DMPIM-DMPIM-SMPIM-SMCBTCBTDVMRPDVMRPPIMPIMDense Mode,DMDense Mode,DM密集模式协议密集模式协议密集模式协议密集模式协议Sparse Mode,SMSparse Mo
50、de,SM稀疏模式协议稀疏模式协议稀疏模式协议稀疏模式协议Link StateLink State链路状态协议链路状态协议链路状态协议链路状态协议3434LS,DM and SM Protocolsn nLSLS（Link StateLink State，链路状态）协议，链路状态）协议，链路状态）协议，链路状态）协议n n通过扩散多播链路状态信息形成（通过扩散多播链路状态信息形成（通过扩散多播链路状态信息形成（通过扩散多播链路状态信息形成（S,GS,G）n nDMDM（Dense ModeDense Mode，密集模式）协议，密集模式）协议，密集模式）协议，密集模式）协议n nPUSHPUSH