module 4-mplshc120118000 mpls协议原理

1、MPLS协议原理Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.前言本课程分析了传统IP在转发速率、Qos和流量工程方面的缺陷，介绍了MPLS转发的基本特点。Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page1培训目标学完本课程后，您应该能： 描述IP转发流程 描述IP转发的缺点 解释MPLS转发基本原理 描述MPLS应用Copyright 2012 Huawei Technologies Co.,

2、 Ltd. All rights reserved.Page2目录MPLS概述MPLS基本原理MPLS环路检测Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page3目录MPLS 概述1.1 传统IP转发1.2 MPLS 转发特点1.3 MPLS应用Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page4传统IP转发SWDSWASWBSWC v1v1 /30 v2v2 /30 v3v3 10.1.

3、1.8/30/24/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page5/30/30Data传统IP转发(SWA)SWA v/30/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page6/30 DataNetworkNexthop/2410

4、.1.0.1/3/30/3/30/30/24传统IP转发(SWB)SWB v1 /30 v/30Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page7NetworkNexthop/24/30/310.1

5、.1.4/30/3/30/24传统IP转发(SWC)SWC v2 /30 v3/30Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page8NetworkNexthop/24/30/30/3/3010.1.1

6、.10/30/240传统IP转发(SWD)SWD v3 /30/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page9/30NetworkNexthop/24/30/30/300/3/24/3210.2

7、.0.1传统IP转发在流量工程方面的缺陷Network A100% TrafficSWCGEGESWASWESWDSWBSWFFEFENetwork C100% TrafficFESWGSWHNetwork BCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page10MPLS标签转发/32SWA v1v1 /30SWBSWCSWD v2v2 /30 v3v3 /30MPLS Domain/24/24MPLS Heade

8、rDataIP HeaderCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page11IPHeaderDataIPHeaderData1039IPHeaderData1029IPHeaderData1024IPHeaderDataMPLS VPN应用VPNAVPNACECEPEPPPEVPNBVPNBCECEPEPPPECECEVPNAVPNACEMPLS DomainCEVPNBVPNBCopyright 2012 Huawei Technologies Co., Ltd. All rights reserv

9、ed.Page12MPLS TE应用Network ASWC70% TrafficSWA30% TrafficGEGESWDSWESWBSWFFE70% TrafficFENetwork CFE30% TrafficSWGSWHNetwork BCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page13MPLS Qos应用Classify TrafficMap Map Mapto DSCPPQ/CQ/CBQaccordinginto DSCPlabeltoEXPtoEXPPEPPPEMPLS DomainNet

10、work ANetwork BCECECopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page14目录MPLS概述MPLS基本原理MPLS环路检测Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page15目录MPLS基本原理2.1 MPLS基本结构2.2 MPLS标签格式2.3 MPLS转发流程传统IP转发Copyright 2012 Huawei Technologies Co., Ltd. All rights reserve

11、d.Page16MPLS网络模型SWFSWGSWDSWASWBSWCLSPLERLERLSRSWEMPLS DomainLER LSRLSPLabel Edge Router Label Switch RouterLabel Switch PathIP NetworkIP NetworkCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page17IPHeaderDataIPHeaderData1039IPHeaderData1029IPHeaderData1024IPHeaderDataMPLS结构交换路由信息标

12、签交换接收IP报文发送IP报文接收带标签报文发送带标签报文Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page18控制平面数据平面Label Forwarding TableIP Forwarding TableLabel Distribution ProtocolIP Routing TableRouting Protocol目录MPLS基本原理2.1 MPLS基本结构2.2 MPLS标签格式2.3 MPLS转发流程传统IP转发Copyright 2012 Huawei Technologies Co.,

13、Ltd. All rights reserved.Page19帧模式MPLS二层帧格式MPLS帧模式封装Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page20Frame HeaderMPLSHeaderIP HeaderPayloadFrame HeaderIP HeaderPayloadMPLS Header0192022232431 MPLS头部总长度为4bytes (32bits) 标签Label长度20bits EXP（Experimental Use）长度3bits S（Bottom of Sta

14、ck）长度1bit TTL长度8bitsCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page21LABELEXPSTTLMPLS标签嵌套PID=MPLS-IPS=1S=0S=0PID 标识二层头部后面的报文类型 Ethernet 0x0800 IPv4 0x8847 MPLS 单播报文 0x8848 MPLS多播报文 PPP 0x8021 IPv4 0x8281 MPLS 单播报文 0x8283 MPLS多播报文S 标识是否是栈底标签标签嵌套应用 MPLS VPN MPLS TECopyright 2012

15、Huawei Technologies Co., Ltd. All rights reserved.Page22Frame HeaderLabel 1Label 2Label 3IP HeaderPayload目录MPLS基本原理2.1 MPLS基本结构2.2 MPLS标签格式2.3 MPLS转发流程传统IP转发Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page23MPLS转发Ingress LER/32SWA v1v1 /30SWDSWBSWC v2v2 /3

16、0 v3v3/30MPLS Domain/24/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page24/30/30 Data1030IPHeaderDataMPLS转发Ingress LERdisplaympls lsp include 24verboseLSPInformation: LDPLSPNo VrfIndex Fec Nexthop In-Label Out-LabelIn-In

17、terface Out-Interface LspIndex TokenLsrType:/24NULL 1030-Vlanif1102490x22005Ingress 0x0 PUSH 1500822secOutgoingtokenLabel Operation Mpls-Mtu TimeStamp FEC：Forwarding Equivalence Classes（转发等价类） NHLFE：Next Hop Label Forwarding Entry （下一跳标签转发表项）Copyright 2012 Huawei Technologies Co., L

18、td. All rights reserved.Page25MPLS转发Ingress LER（SWA）FTN：FEC to NHLFE（FEC到NHLFE）/32SWASWBSWCSWD v1v1 /30 v2v2 /30 v3v3 /30MPLS Domain/24/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page26/30/30 DataFECNHLFEN

19、extHopOut InterfaceLabel OperationOthersVlanif1Push1030IPHeaderDataMPLS转发LSR （SWB）/32SWA v1v1 /30SWDSWBSWC v2v2 /30 v3v3 /30MPLS Domain/24/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page27/30/3010.

20、2.0.1 Data1030IPHeaderData1030IPHeaderDataMPLS转发LSR (SWB)ILM Incoming Label Mapdisplaympls lsp include 24in-label1030verboseLSPInformation: LDPLSPNo VrfIndex Fec Nexthop In-Label Out-LabelIn-Interface Out-Interface LspIndex TokenLsrType:/2410301030-Vlanif2102560x2200cTransi

21、t 0x0 SWAP 150011100secOutgoingtokenLabel Operation Mpls-Mtu TimeStampCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page28MPLS转发LSR (SWC)/32SWAv1SWBSWCSWDv1v2v2v3v3/30/30/30MPLS Domain/24/24Copyright 2012 Huawei Technologies Co., Ltd.

22、 All rights reserved.Page29/30/30DataInLabelNHLFENextHopOut InterfaceLabel OperationOthers10300Vlanif3SWAP11003320IPHeaderData1030IPHeaderData1030IPHeaderDataMPLS数据转发LSR （SWC）displaympls lsp include 24in-label1030verboseLSPInformation: LDPLSPNo VrfIndex Fec N

23、exthop In-Label Out-LabelIn-Interface Out-Interface LspIndex Token LsrType:/24010301032-Vlanif3102680x22015Transit 0x0 SWAP 150040secOutgoingtokenLabel Operation Mpls-Mtu TimeStampCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page30MPLS转发Egress LER （SWD）/32

24、SWA v1v1 /30SWBSWCSWD v2v2 /30 v3v3 /30MPLS Domain/24/24Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page3 Data/30/30 DataInLabelNHLFENextHopOut InterfaceLabel OperationOthers103-POP103Data

25、1030 Data1030 Data1030DataMPLS转发Egress LER （SWD）displaympls lsp include 24in-label1032verboseLSPInformation: LDPLSPNo VrfIndex Fec Nexthop In-Label Out-LabelIn-Interface Out-Interface LspIndex Token LsrType:/241032NULL- 102580x0 Egress 0x0 POP-924sec

26、 40secOutgoingtokenLabel Operation Mpls-Mtu TimeStamp TimeStampCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page32目录MPLS概述MPLS基本原理MPLS环路检测Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page33目录MPLS环路检测3.1 MPLS TTL环路检测3.2 LDP环路检测Copyright 2012 Huawei Technologies

27、 Co., Ltd. All rights reserved.Page34MPLS环路检测IGP环路检测机制TTL环路检测 帧模式的MPLS中使用TTL 信元模式的MPLS中无TTLLDP环路检测机制 距离向量法 最大跳数法Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page35MPLS对TTL的处理Label TTL 减1，拷贝回 IP TTL.IP TTL 减1，并拷贝到Label TTLIP TTL 不变，Label TTL 减/32SWB/32SWC/32S

28、WD/32SWA v1v1 /30 v2v2 /30 v3v3 /30MPLS Domain/24/24Label TTLIP TTLCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page36791010108810MPLS TTL配置与实例分析/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v

29、3v3 /30v1v3MPLS Domainv3v1ping-h11 SWJSWKCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page37/30/30MPLS TTL配置与实例分析debug mpls packetdebug ipterminalterminalpacket acl 3000 monitor debugging*0.86297391 SWA IP/8/debug_case: Receiving, interface = Seria

30、l3, version =4, headlen = 20, tos= 0,pktlen = 84, pktid = 2273, offset = 0, ttl = 11, protocol = 1,checksum = 37572, s = , d = prompt: Receiving IP packet from Serial3*0.86297391 SWA IP/8/debug_case:Sending, pktlen = checksuminterface = Serial3, version = 4, headlen = 20, tos =0,84,

31、pktid = 2273, offset = 0, ttl = 10, protocol= 37572, s = , d = =1,prompt: Sending the packet by lsp*0.86297391 SWA MFW/8/MPLSFW PACKET:PUSH Label=1030, EXP=0, TTL=10Sending to V1, PktLen=88, Label(s)=1030, EXP=0, TTL=10Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.

32、Page38MPLS TTL配置与实例分析debug mpls packetdebug ipterminalterminalpacket acl 3000 monitor debugging*0.189653734 SWB MFW/8/MPLSFW PACKET:Receiving from V1, PktLen=88, Label(s)=1030, SWAP Label=1029, EXP=0, TTL=9EXP=0, TTL=10Sending toV2, PktLen=88, Label(s)=1029,EXP=0, TTL=9debugdebugmpls packetippacket

33、acl 3000 monitor debuggingterminalterminal*0.189533719 SWC MFW/8/MPLSFWReceiving from V2, PktLen=88, SWAP Label=3, TTL=8Sending to V3, Dest=,PACKET:Label(s)=1029, EXP=0, TTL=9Nexthop=0Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page39MPLS TTL配置与实例分析debug mpls pac

34、ketdebug ipterminalterminalpacket acl 3000 monitor debugging*0.64991297 SWD IP/8/debug_case:Receiving, interface = Serial3, version = 4, headlen = 20, tos= 0,pktlen = 84, pktid = 2273, offset = 0, ttl = 8, protocolchecksum = 38340, s = , d = prompt: Receiving IP packet from Serial3*0

35、.64991297 SWD IP/8/debug_case:Sending, interface = Serial1, version = 4, headlen = 20,pktlen = 84, pktid = 2273, offset = 0, ttl = 7, protocolchecksum = 38596, s = , d = prompt: Sending the packet from Serial3 at Serial1= 1,tos = 1,0,tracert tracerouteto 316294(10.2.0

36、.1) 30 hops max,40 bytespacket12345ms ms ms329494ms ms ms1 ms6294msms ms0 125 ms125125 ms 156 ms156 ms156 msCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page40MPLS对TTL的处理Label TTL 减1，去掉标签。IP TTL 减1，但不拷贝Label TTL。Label TTL 强制设为255IP TTL 不变，L

37、abel TTL 减1。/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30MPLS Domain/24/24Label TTLIP TTLCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page41925410255101025310MPLS TTL配置与实例分析SWmplsSW-mplsundo ttlpropagatepub

38、lic/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30v3v1MPLS Domainv3v1ping-h 11 SWJSWKCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page4/30/30MPLS TTL配置与实例分析debug mpls packetdebug ipterminalterminalpa

39、cket acl 3000 monitor debugging*0.81886516 SWA IP/8/debug_case: Receiving, interface = Serial3, version =4, headlen = 20, tos= 0,pktlen = 84, pktid = 1318, offset = 0, ttl = 11, protocol = 1,checksum = 38527, s = , d = prompt: Receiving IP packet from Serial3*0.81886516 SWA IP/8/debu

40、g_case:Sending, pktlen = checksuminterface = Serial3, version = 4, headlen = 20, tos = 84, pktid = 1318, offset = 0, ttl = 10, protocol = 1,= 38527, s = , d = 0,prompt: Sending the packet by lsp*0.81886516 SWA MFW/8/MPLSFW PACKET:PUSH Label=1030, EXP=0, TTL=255Sending to V1, PktLen=8

41、8, Label(s)=1030, EXP=0, TTL=255Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page43MPLS TTL配置与实例分析debug mpls packetdebug ipterminalterminalpacket acl 3000 monitor debugging*0.99910344 SWD IP/8/debug_case: Receiving, interface = Serial3, version =4, headlen = 20, tos= 0,pktlen = 8

42、4, pktid = 9625, offset = 0, ttl = 10, protocol = 1,checksum = 30476, s = , d = prompt: Receiving IP packet from Serial3*0.99910344 SWD IP/8/debug_case:Sending, pktlen = checksuminterface = Serial1, version = 4, headlen = 20, tos = 84, pktid = 9625, offset = 0, ttl = 9, protocol = 1,

43、= 30732, s = , d = 0,prompt: Sending the packet from Serial3 at Serial1Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page44MPLS TTL配置与实例分析/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30v3v1MPLS Domainv3v1SWJtr

44、acertSWKtraceroute to()30hops max,40 bytespacket123 31 ms31 ms32 ms125 ms125 ms0 156 ms94 ms 125 ms125 msCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page45/30/30MPLS TTL配置与实例分析The first traceroute packet with TTL=1

45、is dropped by SwitchA/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30v3v1MPLS Domainv3v1DiscardSWJSWKCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page46/30/301MPLS TTL配置与实例分析DiscardThe first traceroute packet

46、with TTL=1 is dropped by SwitchA/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30v3v1MPLS Domainv3v1SWJSWKCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page47/30/302125412551TTL和环路检测/32SWB/32SWC4.4

47、.4.4/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30MPLS Domain/24/24Label TTLIP TTLCopyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page48.11071081079101010目录MPLS环路检测3.1 MPLS TTL环路检测3.2 LDP环路检测Copyright 2012 Huawei Technologies Co., Ltd. All rights reserved.Page49LDP路径向量法Label Request (length 3) )(,,)Label Request(length 2) )(,)Label Request (length 1 )()/32SWB/32SWC/32SWD/32SWA v1v1 /30 v2v2 /30 v3v3 /30MPLS Doma