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