Internet 路由结构 英文版PDF电子书下载

Part I The Contemporary Internet 3

Chapter1 Evolution of the Internet 5

Origins and Recent History of the Internet 5

From ARPANET to NSFNET 7

The Internet Today 8

NSFNET Solicitations 10

Network Access Points 10

NAP Manager Solicitation 11

What Is a NAP? 11

Federal Internet eXchange 12

Commercial Internet eXchange 12

Current Physical Configurations at the NAP 13

An Alternative to NAPs: Direct Interconnections 14

Routing Arbiter Project 14

The Very High-Speed Backbone Network Service 18

Transitioning the Regional Networks from the NSFNET 21

NSF Solicits NIS Managers 22

Directory and Database Services 23

Network Information Services 23

Creation of the InterNIC 23

Registration Services 25

NIC Support Services 25

Other Internet Registries 25

ARIN 26

RIPE NCC 26

APNIC 27

Internet Routing Registries 27

The Once and Future Internet 28

Next-Generation Internet Initiative 28

Internet2 30

Abilene 31

Looking Ahead 32

Frequently Asked Questions 34

References 35

ISP Services 37

Dedicated Internet Access 37

Chapter2 ISP Services and Characteristics 37

Frame Relay and ATM Internet Access 38

Dialup Services 39

Digital Subscriber Line 40

Cable Modems 41

Dedicated Hosting Services 41

ISP Service Pricing, Service-Level Agreements, and Technical Characteristics 42

ISP Service Pricing 42

Other ISP Services 42

Service-Level Agreements 43

ISP Backbone Selection Criteria 43

Demarcation Point 50

Looking Ahead 53

Frequently Asked Questions 54

Chapter3 IP Addressing and Allocation Techniques 57

History of Internet Addressing 57

Basic IP Addressing 57

Basic IP Subnetting 60

VLSMs 62

IP Address Space Depletion 65

IP Address Allocation 66

Classless Interdomain Routing 67

Private Addressing and Network Address Translation 79

IP Version6 82

Looking Ahead 86

Frequently Asked Questions 87

References 89

Part II Routing Protocol Basics 91

Chapter4 Interdomain Routing Basics 93

Overview of Routers and Routing 93

Basic Routing Example 94

Routing Protocol Concepts 96

Distance Vector Routing Protocols 96

Link-State Routing Protocols 99

Segregating the World into Autonomous Systems 101

Static Routing, Default Routing, and Dynamic Routing 101

Autonomous Systems 102

Looking Ahead 107

Frequently Asked Questions 108

References 109

Chapter5 Border Gateway Protocol Version 4 111

How BGP Works 112

BGP Message Header Format 115

BGP Neighbor Negotiation 116

Finite State Machine Perspective 118

NOTIFICATION Message 120

UPDATE Message and Routing Information 122

KEEPALIVE Message 122

BGP Capabilities Negotiation 127

Multiprotocol Extensions for BGP 128

TCP MD5 Signature Option 129

Looking Ahead 131

Frequently Asked Questions 132

References 133

Part III Effective Internet Routing Designs 135

Building Peer Sessions 137

Chapter 6 Chapter Tuning BGP Capabilities 137

Physical Versus Logical Connections 139

Obtaining an IP Address 140

Authenticating the BGP Session 140

BGP Continuity Inside an AS 141

Synchronization Within an AS 142

Sources of Routing Updates 144

Injecting Information Dynamically into BGP 144

Injecting Information Statically into BGP 147

ORIGIN of Routes 148

An Example of Static Versus Dynamic Routing: Mobile Networks 150

Overlapping Protocols: Backdoors 150

The Routing Process Simplified 152

BGP Routes: Advertisement and Storage 153

The BGP Routing Information Bases 154

Routes Received from Peers 155

Input Policy Engine 155

Routes Used by the Router 155

Sample Routing Environment 156

Output Policy Engine 156

Routes Advertised to Peers 156

BGP Decision Process Summary 158

Controlling BGP Routes 159

BGP Path Attributes 160

NEXT_HOP Behavior on Multiaccess Media 172

NEXT_HOP Behavior Over Nonbroadcast Multiaccess Media 173

Use of next-hop-self versus Advertising DMZ 174

Using Private Ass 175

AS_PATH and Route Aggregation Issues 177

AS_PATH Manipulation 178

Route Filtering and Attribute Manipulation 180

Inbound and Outbound Filtering 181

The Route Filtering and Manipulation Process 182

Peer Groups 190

BGP-4 Aggregation 192

Aggregate Only, Suppressing the More-Specific Routes 192

Aggregate Plus More-Specific Routes 193

Aggregate with a Subset of the More-Specific Routes 195

Loss of Information Inside Aggregates 196

Changing the Attributes of the Aggregate 196

Forming the Aggregate Based on a Subset of the More-Specific Routes 196

Looking Ahead 197

Frequently Asked Questions 199

References 201

Chapter 7 Redundancy, Symmetry, and Load Balancing 203

Redundancy 203

Geographical Restrictions Pressure 204

Setting Default Routes 205

Symmetry 210

Load Balancing 210

Specific Scenarios: Designing Redundancy, Symmetry, and Load Balancing 212

Scenario1 : Single-Homing 213

Scenario2: Multihoming to a Single Provider 213

Scenario3: Multihoming to Different Providers 223

Scenario4: Customers of the Same Provider with a Backup Link 228

Scenario5: Customers of Different Providers with a Backup Link 231

Looking Ahead 236

Frequently Asked Questions 237

References 239

Chapter8 Controlling Routing Inside the Autonomous System 241

Interaction of Non-BGP Routers with BGP Routers 241

Injecting BGP into the IGP 241

Following Defaults Inside an AS 242

Defaults Inside the AS: Primary/Backup BGP Policy 244

BGP Policies Conflicting with Internal Defaults 244

Defaults Inside the AS: Other BGP Policies 250

Policy Routing 252

Policy Routing Based on Traffic Source 252

Policy Routing Based on Traffic Source/Destination 253

Policy Routing Defaults to Dynamic Routing 254

Other Applications of Policy Routing 255

Looking Ahead 257

Frequently Asked Questions 258

Route Reflectors 261

Chapter 9 Controlling Large-Scale Autonomous Systems 261

Internal Peers Without Route Reflectors 262

Internal Peers with Route Reflectors 263

Naming Conventions and Rules of Operation 264

Redundancy Issues and Multiple Route Reflectors in an AS 265

Route Reflection Topology Models 266

Route Reflectors and Peer Groups 269

Confederations 271

Confederation Drawbacks 273

Recommended Confederation Design 274

Route Exchange and BGP Decisions with Confederations 274

Confederations Versus Route Reflectors 275

Controlling IGP Expansion 275

Segmenting the AS with Multiple Regions Separated by IBGP 277

Segmenting the AS with Multiple Regions Separated by EBGP 279

Looking Ahead 283

Frequently Asked Questions 284

References 285

IGP Instability 287

Chapter 10 Designing Stable Internets 287

Route Instabilities on the Internet 287

Faulty Hardware 288

Software Problems 288

Insufficient CPU Power 288

Insufficient Memory 289

Network Upgrades and Routine Maintenance 289

Link Congestion 290

BGP Stability Features 290

Human Error 290

Controlling Route and Cache Invalidation 291

BGP Route Refresh 291

Route Dampening 292

Looking Ahead 296

Frequently Asked Questions 297

Part IV Internet Routing Device Configuration 299

Chapter 11 Configuring Basic BGP Functions and Attributes 301

Building Peering Sessions 301

BGP Route Maps 308

Route Filtering and Attribute Manipulation 308

Prefix Lists 310

Identifying and Filtering Routes Based on the NLRI 312

Identifying and Filtering Routes Based on the AS_PATH 315

Peer Groups 316

Sources of Routing Updates 318

Injecting Information Dynamically into BGP 318

Injecting Information Statically into BGP 325

Overlapping Protocols: Backdoors 326

BGP Attributes 328

The NEXT_HOP Attribute 331

The AS_PATH Attribute 332

The LOCAL_PREF Attribute 335

The MULTI_EXIT_DISC Attribute 337

The COMMUNITY Attribute 340

BGP-4 Aggregation 342

Aggregate Only, Suppressing the More-Specific 343

Aggregate Plus More-Specific Routes 346

Aggregate with a Subset of the More-Specific Routes 350

Loss of Information Inside Aggregates 354

Changing the Aggregate s Attributes 357

Forming the Aggregate Based on a Subset of Specific Routes 359

Looking Ahead 361

Chapter 12 Configuring Effective Internet Routing Policies 365

Redundancy, Symmetry, and Load Balancing 365

Dynamically Learned Defaults 365

Statically Set Defaults 367

Multihoming to a Single Provider 370

Multihoming to Different Providers 384

Customers of the Same Provider with a Backup Link 388

Customers of Different Providers with a Backup Link 391

Following Defaults Inside an AS 395

BGP Policies Conflicting with the Internal Default 398

Policy Routing 411

Route Reflectors 415

Confederations 419

Controlling Route and Cache Invalidation 424

BGP Soft Reconfiguration 425

Outbound Soft Reconfiguration 425

Inbound Soft Reconfiguration 425

BGP Route Refresh 429

BGP Outbound Request Filter Capability 431

Route Dampening 432

Looking Ahead 435

Part V Appendixes 439

Appendix A BGP Command Reference 441

Interesting Organizations 449

Research and Education 449

Miscellaneous 449

Books 450

TCP/IP-Related Sources 450

Routing-Related Sources 450

Internet Request For Comments 450

When to Use BGP ORF 455

Appendix C BGP Outbound Route Filter (ORF) 455

Configuration 456

Enabling the BGP ORF Capability as Send-Mode 456

Enabling the BGP ORF Capability as Receive-Mode 456

Ensuring Backward Compatibility of the Old Knobs 457

EXEC Commands 457

Pushing Out A Prefix List and Receiving a Route Refresh from a Neighbor 457

Closing Remarks 458

Displaying Changes to the Neighbor BGP Table 458

Displaying the Prefix List Received from a Neighbor 458

Appendix D Multiprotocol BGP (MBGP) 461

The Motivation Behind the New Command-Line Interface 461

Organizing Command Groups in the New Configuration 462

activate 464

Old Style 464

AF Style 464

Peer Groups 465

AF Style 465

network 465

Old Style 465

Old Style 466

AF Style 466

Route Maps 466

Old Style 466

AF Style 467

Old Style 468

AF Style 468

Redistribution 468

Route Reflector 469

Old Style 469

AF Style 469

Aggregation 469

Old Style 470

AF Style 470

List of BGP Commands 470

Upgrading to the AF Style 472

References 473

Index 475