本书涵盖了MPLS的理论、配置和网络设计方面的主要内容以及一种主要的MPLS应用——基于MPLS的VPN。本书通过配置范例、设计和部署指南以及大量的案例研究，阐述了MPLS/VPN的体系结构及其所有的机制；同时介绍了MPLS故障诊断、MPLS/VPN故障诊断，并在每章的*后提供了自测题，以帮助读者准备CCIP MPLS考试。本书共17章。第1～7章介绍MPLS技术及其配置，包括帧模式MPLS和信元模式MPLS、在交换式WAN介质上运行帧模式MPLS、**MPLS主题、MPLS迁移和配置案例研究以及MPLS故障诊断等；第8-17章介绍了基于MPLS的虚拟专网，包括实现虚拟专网的方式、MPLS/VPN体系结构、提供商边缘到客户边缘的连接方式、**MPLS/VPN拓扑、**MPLS/VPN主题、MPLS/VPN部署指南、运营商的运营商VPN解决方案、IP隧道技术到MPLS/VPN的迁移案例研究以及MPLS/VPN故障诊断等。
本书是CCIP考生准备MPLS VPN考试的**教材，也是理解、设计和部署基于MPLS的VPN的实用指南。通过阅读本书，可极大地增加CCIP考生通过MPLS VPN考

Part I MPLS Technology and Configuration 3

Chapter 1 Multiprotocol Label Switching (MPLS) Architecture Overview 5
* Scalability and Flexibility of IP-based Forwarding 5
·Network Layer Routing Paradigm 5
·Differentiated Packet Servicing 9
·Independent Forwarding and Control 10
·External Routing Information Propagation 10
* Multiprotocol Label Switching (MPLS) Introduction 11
·MPLS Architecture-The Building Blocks 13
·Label Imposition at the Network Edge 15
·MPLS Packet Forwarding and Label Switched Paths 17
* Other MPLS Applications 19
* Summary 20
* Review Questions 21

Chapter 2 Frame-mode MPLS Operation 23
* Frame-mode MPLS Data Plane Operation 25
·MPLS Label Stack Header 26
·Label Switching in Frame-mode MPLS 28
* Label Bindings and Propagation in Frame-mode MPLS 31
·LDP/TDP Session Establishment 31
·Label Binding and Distribution 34
·Convergence in a Frame-mode MPLS Network 37
* Penultimate Hop Popping 40
* MPLS Interaction with Border Gateway Protocol 42
* Summary 45
* Review Questions 46

Chapter 3 Cell-mode MPLS Operation 49
* Control-plane Connectivity Across an LC-ATM Interface 51
·MPLS Control-plane Connectivity in Cisco IOS Software 52
·Control-plane Implementation in an ATM Switch 54
* Labeled Packet Forwarding Across an ATM-LSR Domain 55
* Label Allocation and Distribution Across an ATM-LSR Domain 56
·VC Merge 58
·Convergence Across an ATM-LSR Domain 61
* Summary 62
* Review Questions 63

Chapter 4 Running Frame-mode MPLS Across Switched WAN Media 65
* Frame-mode MPLS Operation Across Frame Relay 65
* Frame-mode MPLS Operation Across ATM PVCs 67
·Frame-mode and Cell-mode MPLS Across the Same ATM Interface 69
* Summary 70
* Review Questions 71

Chapter 5 Advanced MPLS Topics 73
* Controlling the Distribution of Label Mappings 73
* MPLS Encapsulation Across Ethernet Links 77
·IP MTU Path Discovery 78
·Ethernet Switches and MPLS MTU 80
* MPLS Loop Detection and Prevention 81
·Loop Detection and Prevention in Frame-mode MPLS 81
·Loop Detection and Prevention in Cell-mode MPLS 82
* Traceroute Across an MPLS-enabled Network 88
* Route Summarization Within an MPLS-enabled Network 92
* Summary 93
* Review Questions 94

Chapter 6 MPLS Migration and Configuration Case Study 97
* Migration of the Backbone to a Frame-mode MPLS Solution 97
* Pre-migration Infrastructure Checks 99
·Cisco Express Forwarding (CEF) Requirements 100
* Addressing the Internal BGP Structure 101
* Migration of Internal Links to MPLS 103
* Removal of Unnecessary BGP Peering Sessions 105
* Migration of an ATM-based Backbone to Frame-mode MPLS 106
·Cell-mode MPLS Migration 108
* Summary 110
* Review Questions 111

Part II MPLS-based Virtual Private Networks 113

Chapter 7 MPLS Troubleshooting 115
* Quick MPLS-related Checks 116
·Is CEF Enabled Globally? 116
·Is MPLS Enabled? 116
·Is MPLS Enabled on All Interfaces? 117
* MPLS Control Plane Troubleshooting 118
·Verify Local TDP/LDP Parameters 118
·Verify Correct Operation of TDP/LDP Hello Protocol 118
·Check TDP/LDP Sessions 120
·Check the Label Exchange 121
* MPLS Data Plane Troubleshooting 122
·Monitoring Interface-level CEF 122
·Monitoring End-to-end MPLS Path 123
·Oversized Packet Issues 124
* Summary 125
* Review Questions 126

Chapter 8 Virtual Private Network (VPN) Implementation Options 129
* Virtual Private Network Evolution 129
·Modern Virtual Private Networks 132
* Business Problem-based VPN Classification 132
* Overlay and Peer-to-peer VPN Model 135
·Overlay VPN Model 135
·Peer-to-peer VPN Model 138
* Typical VPN Network Topologies 143
·Hub-and-spoke Topology 144
·Partial- or Full-mesh Topology 148
·Hybrid Topology 150
·Simple Extranet Topology 150
·Central-services Extranet 152
·VPDN Topology 155
·Managed Network VPN Topology 157
* Summary 158
* Review Questions 159

Chapter 9 MPLS/VPN Architecture Overview 161
* Case Study: Virtual Private Networks in SuperCom Service Provider Network 162
* VPN Routing and Forwarding Tables 165
* Overlapping Virtual Private Networks 167
* Route Targets 171
* Propagation of VPN Routing Information in the Provider Network 172
·Multiprotocol BGP in the SuperCom Network 174
* VPN Packet Forwarding 177
* Summary 179
* Review Questions 180

Chapter 10 MPLS/VPN Architecture Operation 183
* Case Study: Basic MPLS/VPN Intranet Service 184
* Configuration of VRFs 186
* Route Distinguishers and VPN-IPv4 Address Prefixes 187
·Configuration of the Route Distinguisher 191
* BGP Extended Community Attribute 193
·Route Target BGP Extended Community 194
·Site of Origin BGP Extended Community 196
·BGP Extended Community Attribute Format 198
* Basic PE-to-CE Link Configuration 200
·PE-to-CE Link Configuration-Static Routing 200
·PE-to-CE Link Configuration-RIP Version 2 202
* Association of Interfaces to VRFs 204
* Multiprotocol BGP Usage and Deployment 204
·Configuration of Multiprotocol BGP 207
·Enhanced BGP Decision Process for VPN-IPv4 Prefixes 211
* Outbound Route Filtering (ORF) and Route Refresh Features 213
·Automatic Route Filtering on PE Routers 213
·Refreshing Routing Information Between PE Routers 215
·ORF for PE Routers 218
* MPLS/VPN Data Plane-Packet Forwarding 220
·Summary 221
·Review Questions 222

Chapter 11 Provider Edge (PE) to Customer Edge (CE) Connectivity Options 225
* VPN Customer Access into the MPLS/VPN Backbone 225
* BGP-4 Between Service Provider and Customer Networks 227
* Open Shortest Path First (OSPF) Between PE and CE Routers 230
* Separation of VPN Customer Routing Information 232
* Propagation of OSPF Routes Across the MPLS/VPN Backbone 235
·BGP Extended Community Attribute for OSPF Routes 237
* PE-to-CE Connectivity-OSPF with Site Area 0 Support 238
* PE-to-CE Connectivity-OSPF Without Site Area 0 Support 242
* VPN Customer Connectivity-MPLS/VPN Design Choices 244
·Migrating Customers Using iBGP in Their Network to MPLS/VPN Service 248
·Autonomous System Number Override 250
* Summary 253
* Review Questions 253

Chapter 12 Advanced MPLS/VPN Topologies 255
* Intranet and Extranet Integration 255
* Central Services Topology 258
* MPLS/VPN Hub-and-spoke Topology 261
·Deployment of the AllowAS-in Feature 264
* Summary 266
* Review Questions 267

Chapter 13 Advanced MPLS/VPN Topics 269
* MPLS/VPN: Scaling the Solution 271
* Routing Convergence Within an MPLS-enabled VPN Network 271
·Convergence Within the Service Provider Backbone 273
·Convergence Between VPN Sites 275
* Advertisement of Routes Across the Backbone 280
·BGP for VPN-IPv4 and IPv4 Routing Information 281
·Full Mesh of MP-iBGP Between PE Routers 285
·Separation of MP-iBGP Sessions Between PE Routers 286
* Introduction of Route Reflector Hierarchy 288
·Route Reflection of PE Routes to Aid Scaling 290
·Route Reflector Partitioning 292
·Standard Community Filtering on PE Routers 294
·Route Target Attribute-based Filtering on Route Reflectors 297
·Route Reflection and ORF Capability 299
* BGP Confederations Deployment 300
·BGP Confederations-Single IGP Environment 305
·BGP Confederations-Multiple IGP Environment 306
* PE Router Provisioning and Scaling 311
* Additional Connectivity Requirements-Internet Access 312
* Internet Connectivity Through Firewalls 313
* Internet Access-Static Default Routing 315
* Separate BGP Session Between PE and CE Routers 320
* Internet Connectivity Through Dynamic Default Routing 328
·Dynamic Default Routing-Route Target Assignment 328
·Association of the Global Routing Table with a VRF 330
* Additional Lookup in the Global Routing Table 334
* Internet Connectivity Through a Different Service Provider 335
* Summary 336
* Review Questions 337

Chapter 14 Guidelines for the Deployment of MPLS/VPN 339
* Introduction to MPLS/VPN Deployment 339
* IGP to BGP Migration of Customer Routes 339
* Multiprotocol BGP Deployment in an MPLS/VPN Backbone 344
·VPN Routes and Next-hop Forwarding 345
·PE Router Loopback Address Configuration 348
* MPLS/VPN Deployment on LAN Interfaces 355
* Network Management of Customer Links 358
·Advertisement of Routes with Different Extended Communities 359
·Use of Standard BGP Communities for Route Filtering 363
·Advertisement of Routes with Different Route Targets Using Export Maps 368
* Use of Traceroute Across an MPLS/VPN Backbone 371
* Summary 374
* Review Questions 375

Chapter 15 Carrier's Carrier and Inter-provider VPN Solutions 377
* Carrier's Carrier Solution Overview 378
* Carrier's Carrier Architecture-Topologies 381
·ISP with No MPLS Deployment Within POP Sites 382
·ISP with MPLS Deployed Within POP Sites 388
* Hierarchical Virtual Private Networks 392
* Inter-provider VPN Solutions 394
·Inter-provider VPN-Exchange of VPN-IPv4 Across Boundaries 396
·Inter-provider VPN-Multi-hop eBGP Between Customer Sites 402
* Summary 404
* Review Questions 405

Chapter 16 IP Tunneling to MPLS/VPN Migration Case Study 407
* Existing VPN Solution Deployment-IP Tunneling 408
* Definition of VPNs and Routing Policies for PE Routers 410
* Definition of VRFs Within the Backbone Network 411
* VRF and Routing Polices for SampleNet VPN Sites 412
* VRF and Routing Policies for SampleNet Internet Access 413
* VRF and Routing Policies for Internet Access Customers 414
* MPLS/VPN Migration-Staging and Execution 414
·Migration of the SampleNet Central Site 415
* Configuration of MP-iBGP on BGP Route Reflectors 418
* Configuration of MP-iBGP on TransitNet PE Routers 420
* Migration of VPN Sites onto the MPLS/VPN Solution 421
* Summary 421
* Review Questions 423

Chapter 17 MPLS VPN Troubleshooting 425
* Quick MPLS-related Checks 426
·Pinging Between the CE Routers 426
·Checking for an End-to-end LSP Between PE Routers 428
·Checking for CEF Switching 429
* In-depth MPLS VPN Troubleshooting 430
·Checking the Egress CE-to-PE Routing Exchange 432
·Checking the Route Export Functionality 434
·Checking the Propagation of MPLS VPN Routes 436
·Checking the Route Import Functionality 437
·Checking the Ingress PE-to-CE Routing Exchange 439
* Summary 441
* Review Questions 441

Appendix A Answers to Review Questions 443
Appendix B Tag-switching and MPLS Command Reference 461

Index 465