Foreword xxiii
Preface xxv
Chapter 1 Introduction And Overview 1
1.1 The Motivation For Internetworking 1
1.2 The TCP/IP Internet 2
1.3 Internet Services 2
1.4 History And Scope Of The Internet 6
1.5 The Internet Architecture Board 7
1.6 The IAB Reorganization 8
1.7 Internet Request For Comments (RFCs) 8
1.8 Internet Growth 9
1.9 Transition To IPv6 12
1.10 Committee Design And The New Version of IP 12
1.11 Relationship Between IPv4 And IPv6 13
1.12 IPv6 Migration 14
1.13 Dual Stack Systems 15
1.14 Organization Of The Text 15
1.15 Summary 16
Chapter 2 Overview Of Underlying Network Technologies 19
2.1 Introduction 19
2.2 Two Approaches To Network Communication 20
2.3 WAN And LAN 21
2.4 Hardware Addressing Schemes 21
2.5 Ethernet (IEEE 802.3) 22
2.6 Wi-Fi (IEEE 802.11) 26
2.7 ZigBee (IEEE 802.15.4) 26
2.8 Optical Carrier And Packet Over SONET (OC, POS) 27
2.9 Point-To-Point Networks 28
2.10 VLAN Technology And Broadcast Domains 28
2.11 Bridging 29
2.12 Congestion And Packet Loss 30
2.13 Summary 31
Chapter 3 Internetworking Concept And Architectural Model 35
3.1 Introduction 35
3.2 Application-Level Interconnection 35
3.3 Network-Level Interconnection 37
3.4 Properties Of The Internet 38
3.5 Internet Architecture 39
3.6 Interconnection Of Multiple Networks With IP Routers 39
3.7 The User's View 41
3.8 All Networks Are Equal 42
3.9 The Unanswered Questions 43
3.10 Summary 43
Chapter 4 Protocol Layering 47
4.1 Introduction 47
4.2 The Need For Multiple Protocols 47
4.3 The Conceptual Layers Of Protocol Software 49
4.4 Functionality Of The Layers 49
4.5 ISO 7-Layer Reference Model 50
4.6 X.25 And Its Relation To The ISO Model 51
4.7 The TCP/IP 5-Layer Reference Model 52
4.8 Locus Of Intelligence 56
4.9 The Protocol Layering Principle 57
4.10 The Layering Principle Applied To A Network 58
4.11 Layering In Mesh Networks 60
4.12 Two Important Boundaries In The TCP/IP Model 62
4.13 Cross-Layer Optimizations 63
4.14 The Basic Idea Behind Multiplexing And Demultiplexing 64
4.15 Summary 66
Chapter 5 Internet Addressing 69
5.1 Introduction 69
5.2 Universal Host Identifiers 69
5.3 The Original IPv4 Classful Addressing Scheme 71
5.4 Dotted Decimal Notation Used With IPv4 72
5.5 IPv4 Subnet Addressing 72
5.6 Fixed Length IPv4 Subnets 75
5.7 Variable-Length IPv4 Subnets 77
5.8 Implementation Of IPv4 Subnets With Masks 77
5.9 IPv4 Subnet Mask Representation And Slash Notation 78
5.10 The Current Classless IPv4 Addressing Scheme 79
5.11 IPv4 Address Blocks And CIDR Slash Notation 82
5.12 A Classless IPv4 Addressing Example 82
5.13 IPv4 CIDR Blocks Reserved For Private Networks 83
5.14 The IPv6 Addressing Scheme 84
5.15 IPv6 Colon Hexadecimal Notation 84
5.16 IPv6 Address Space Assignment 85
5.17 Embedding IPv4 Addresses In IPv6 For Transition 86
5.18 IPv6 Unicast Addresses And /64 87
5.19 IPv6 Interface Identifiers And MAC Addresses 88
5.20 IP Addresses, Hosts, And Network Connections 89
5.21 Special Addresses 90
5.22 Weaknesses In Internet Addressing 94
5.23 Internet Address Assignment And Delegation Of Authority 96
5.24 An Example IPv4 Address Assignment 96
5.25 Summary 98
Chapter 6 Mapping Internet Addresses To Physical Addresses (ARP) 101
6.1 Introduction 101
6.2 The Address Resolution Problem 101
6.3 Two Types Of Hardware Addresses 102
6.4 Resolution Through Direct Mapping 102
6.5 Resolution In A Direct-Mapped Network 103
6.6 IPv4 Address Resolution Through Dynamic Binding 104
6.7 The ARP Cache 105
6.8 ARP Cache Timeout 106
6.9 ARP Refinements 106
6.10 Relationship Of ARP To Other Protocols 108
6.11 ARP Implementation 108
6.12 ARP Encapsulation And Identification 110
6.13 ARP Message Format 110
6.14 Automatic ARP Cache Revalidation 112
6.15 Reverse Address Resolution (RARP) 112
6.16 ARP Caches In Layer 3 Switches 113
6.17 Proxy ARP 114
6.18 IPv6 Neighbor Discovery 115
6.19 Summary 116
Chapter 7 Internet Protocol: Connectionless Datagram Delivery (IPv4, 119
IPv6)
7.1 Introduction 119
7.2 A Virtual Network 119
7.3 Internet Architecture And Philosophy 120
7.4 Principles Behind The Structure 120
7.5 Connectionless Delivery System Characteristics 121
7.6 Purpose And Importance Of The Internet Protocol 122
7.7 The IP Datagram 122
7.8 Datagram Type Of Service And Differentiated Services 127
7.9 Datagram Encapsulation 129
7.10 Datagram Size, Network MTU, and Fragmentation 130
7.11 Datagram Reassembly 134
7.12 Header Fields Used For Datagram Reassembly 135
7.13 Time To Live (IPv4) And Hop Limit (IPv6) 136
7.14 Optional IP Items 137
7.15 Options Processing During Fragmentation 141
7.16 Network Byte Order 143
7.17 Summary 144
Chapter 8 Internet Protocol: Forwarding IP Datagrams 147
8.1 Introduction 147
8.2 Forwarding In An Internet 147
8.3 Direct And Indirect Delivery 149
8.4 Transmission Across A Single Network 150
8.5 Indirect Delivery 151
8.6 Table-Driven IP Forwarding 152
8.7 Next-Hop Forwarding 153
8.8 Default Routes And A Host Example 155
8.9 Host-Specific Routes 156
8.10 The IP Forwarding Algorithm 157
8.11 Longest-Prefix Match Paradigm 158
8.12 Forwarding Tables And IP Addresses 160
8.13 Handling Incoming Datagrams 161
8.14 Forwarding In The Presence Of Broadcast And Multicast 162
8.15 Software Routers And Sequential Lookup 163
8.16 Establishing Forwarding Tables 163
8.17 Summary 163
Chapter 9 Internet Protocol: Error And Control Messages (ICMP) 167
9.1 Introduction 167
9.2 The Internet Control Message Protocol 167
9.3 Error Reporting Vs. Error Correction 169
9.4 ICMP Message Delivery 170
9.5 Conceptual Layering 171
9.6 ICMP Message Format 171
9.7 Example ICMP Message Types Used With IPv4 And IPv6 172
9.8 Testing Destination Reachability And Status (Ping) 173
9.9 Echo Request And Reply Message Format 174
9.10 Checksum Computation And The IPv6 Pseudo-Header 175
9.11 Reports Of Unreachable Destinations 176
9.12 ICMP Error Reports Regarding Fragmentation 178
9.13 Route Change Requests From Routers 178
9.14 Detecting Circular Or Excessively Long Routes 180
9.15 Reporting Other Problems 181
9.16 Older ICMP Messages Used At Startup 182
9.17 Summary 182
Chapter 10 User Datagram Protocol (UDP) 185
10.1 Introduction 185
10.2 Using A Protocol Port As An Ultimate Destination 185
10.3 The User Datagram Protocol 186
10.4 UDP Message Format 187
10.5 Interpretation Of the UDP Checksum 188
10.6 UDP Checksum Computation And The Pseudo-Header 189
10.7 IPv4 UDP Pseudo-Header Format 189
10.8 IPv6 UDP Pseudo-Header Format 190
10.9 UDP Encapsulation And Protocol Layering 190
10.10 Layering And The UDP Checksum Computation 192
10.11 UDP Multiplexing, Demultiplexing, And Protocol Ports 193
10.12 Reserved And Available UDP Port Numbers 194
10.13 Summary 196
Chapter 11 Reliable Stream Transport Service (TCP) 199
11.1 Introduction 199
11.2 The Need For Reliable Service 199
11.3 Properties Of The Reliable Delivery Service 200
11.4 Reliability: Acknowledgements And Retransmission 201
11.5 The Sliding Window Paradigm 203
11.6 The Transmission Control Protocol 205
11.7 Layering, Ports, Connections, And Endpoints 206
11.8 Passive And Active Opens 208
11.9 Segments, Streams, And Sequence Numbers 208
11.10 Variable Window Size And Flow Control 209
11.11 TCP Segment Format 210
11.12 Out Of Band Data 212
11.13 TCP Options 212
11.14 TCP Checksum Computation 214
11.15 Acknowledgements, Retransmission, And Timeouts 216
11.16 Accurate Measurement Of Round Trip Samples 218
11.17 Karn's Algorithm And Timer Backoff 219
11.18 Responding To High Variance In Delay 220
11.19 Response To Congestion 223
11.20 Fast Recovery And Other Response Modifications 225
11.21 Explicit Feedback Mechanisms (SACK and ECN) 227
11.22 Congestion, Tail Drop, And TCP 228
11.23 Random Early Detection (RED) 229
11.24 Establishing A TCP Connection 231
11.25 Initial Sequence Numbers 232
11.26 Closing a TCP Connection 233
11.27 TCP Connection Reset 234
11.28 TCP State Machine 235
11.29 Forcing Data Delivery 236
11.30 Reserved TCP Port Numbers 237
11.31 Silly Window Syndrome And Small Packets 238
11.32 Avoiding Silly Window Syndrome 239
11.33 Buffer Bloat And Its Effect On Latency 242
11.34 Summary 243
Chapter 12 Routing Architecture: Cores, Peers, And Algorithms 247
12.1 Introduction 247
12.2 The Origin Of Forwarding Tables 248
12.3 Forwarding With Partial Information 249
12.4 Original Internet Architecture And Cores 251
12.5 Beyond The Core Architecture To Peer Backbones 253
12.6 Automatic Route Propagation And A FIB 254
12.7 Distance-Vector (Bellman-Ford) Routing 255
12.8 Reliability And Routing Protocols 257
12.9 Link-State (SPF) Routing 258
12.10 Summary 259
Chapter 13 Routing Among Autonomous Systems (BGP) 263
13.1 Introduction 263
13.2 The Scope Of A Routing Update Protocol 263
13.3 Determining A Practical Limit On Group Size 264
13.4 A Fundamental Idea: Extra Hops 266
13.5 Autonomous System Concept 267
13.6 Exterior Gateway Protocols And Reachability 268
13.7 BGP Characteristics 269
13.8 BGP Functionality And Message Types 270
13.9 BGP Message Header 271
13.10 BGP OPEN Message 272
13.11 BGP UPDATE Message 273
13.12 Compressed IPv4 Mask-Address Pairs 274
13.13 BGP Path Attributes 274
13.14 BGP KEEPALIVE Message 276
13.15 Information From The Receiver's Perspective 277
13.16 The Key Restriction Of Exterior Gateway Protocols 278
13.17 The Internet Routing Architecture And Registries 280
13.18 BGP NOTIFICATION Message 280
13.19 BGP Multiprotocol Extensions For IPv6 281
13.20 Multiprotocol Reachable NLRI Attribute 283
13.21 Internet Routing And Economics 284
13.22 Summary 285
Chapter 14 Routing Within An Autonomous System (RIP, RIPng, 289
OSPF, IS-IS)
14.1 Introduction 289
14.2 Static Vs. Dynamic Interior Routes 289
14.3 Routing Information Protocol (RIP) 293
14.4 Slow Convergence Problem 294
14.5 Solving The Slow Convergence Problem 296
14.6 RIP Message Format (IPv4) 297
14.7 Fields In A RIP Message 299
14.8 RIP For IPv6 (RIPng) 299
14.9 The Disadvantage Of Using Hop Counts 301
14.10 Delay Metric (HELLO) 301
14.11 Delay Metrics, Oscillation, And Route Flapping 302
14.12 The Open SPF Protocol (OSPF) 303
14.13 OSPFv2 Message Formats (IPv4) 305
14.14 Changes In OSPFv3 To Support IPv6 310
14.15 IS-IS Route Propagation Protocol 312
14.16 Trust And Route Hijacking 313
14.17 Gated: A Routing Gateway Daemon 313
14.18 Artificial Metrics And Metric Transformation 314
14.19 Routing With Partial Information 315
14.20 Summary 315
Chapter 15 Internet Multicasting 319
15.1 Introduction 319
15.2 Hardware Broadcast 319
15.3 Hardware Multicast 320
15.4 Ethernet Multicast 321
15.5 The Conceptual Building Blocks Of Internet Multicast 321
15.6 The IP Multicast Scheme 322
15.7 IPv4 And IPv6 Multicast Addresses 323
15.8 Multicast Address Semantics 326
15.9 Mapping IP Multicast To Ethernet Multicast 327
15.10 Hosts And Multicast Delivery 328
15.11 Multicast Scope 328
15.12 Host Participation In IP Multicasting 329
15.13 IPv4 Internet Group Management Protocol (IGMP) 330
15.14 IGMP Details 331
15.15 IGMP Group Membership State Transitions 332
15.16 IGMP Membership Query Message Format 333
15.17 IGMP Membership Report Message Format 334
15.18 IPv6 Multicast Group Membership With MLDv2 335
15.19 Multicast Forwarding And Routing Information 337
15.20 Basic Multicast Forwarding Paradigms 339
15.21 Consequences Of TRPF 341
15.22 Multicast Trees 342
15.23 The Essence Of Multicast Route Propagation 343
15.24 Reverse Path Multicasting 344
15.25 Example Multicast Routing Protocols 345
15.26 Reliable Multicast And ACK Implosions 347
15.27 Summary 349
Chapter 16 Label Switching, Flows, And MPLS 353
16.1 Introduction 353
16.2 Switching Technology 353
16.3 Flows And Flow Setup 355
16.4 Large Networks, Label Swapping, And Paths 355
16.5 Using Switching With IP 357
16.6 IP Switching Technologies And MPLS 357
16.7 Labels And Label Assignment 359
16.8 Hierarchical Use Of MPLS And A Label Stack 359
16.9 MPLS Encapsulation 360
16.10 Label Semantics 361
16.11 Label Switching Router 362
16.12 Control Processing And Label Distribution 363
16.13 MPLS And Fragmentation 364
16.14 Mesh Topology And Traffic Engineering 364
16.15 Summary 365
Chapter 17 Packet Classification 369
17.1 Introduction 369
17.2 Motivation For Classification 370
17.3 Classification Instead Of Demultiplexing 371
17.4 Layering When Classification Is Used 372
17.5 Classification Hardware And Network Switches 372
17.6 Switching Decisions And VLAN Tags 374
17.7 Classification Hardware 375
17.8 High-Speed Classification And TCAM 375
17.9 The Size Of A TCAM 377
17.10 Classification-Enabled Generalized Forwarding 378
17.11 Summary 379
Chapter 18 Mobility And Mobile IP 381
18.1 Introduction 381
18.2 Mobility, Addressing, And Routing 381
18.3 Mobility Via Host Address Change 382
18.4 Mobility Via Changes In Datagram Forwarding 383
18.5 The Mobile IP Technology 383
18.6 Overview Of Mobile IP Operation 384
18.7 Overhead And Frequency Of Change 384
18.8 Mobile IPv4 Addressing 385
18.9 IPv4 Foreign Agent Discovery 386
18.10 IPv4 Registration 387
18.11 IPv4 Registration Message Format 388
18.12 Communication With An IPv4 Foreign Agent 388
18.13 IPv6 Mobility Support 389
18.14 Datagram Transmission, Reception, And Tunneling 390
18.15 Assessment Of IP Mobility And Unsolved Problems 391
18.16 Alternative Identifier-Locator Separation Technologies 395
18.17 Summary 396
Chapter 19 Network Virtualization: VPNs, NATs, And Overlays 399
19.1 Introduction 399
19.2 Virtualization 399
19.3 Virtual Private Networks (VPNs) 400
19.4 VPN Tunneling And IP-in-IP Encapsulation 401
19.5 VPN Addressing And Forwarding 402
19.6 Extending VPN Technology To Individual Hosts 404
19.7 Using A VPN With Private IP Addresses 404
19.8 Network Address Translation (NAT) 405
19.9 NAT Translation Table Creation 407
19.10 Variant Of NAT 409
19.11 An Example Of NAT Translation 409
19.12 Interaction Between NAT And ICMP 411
19.13 Interaction Between NAT And Applications 411
19.14 NAT In The Presence Of Fragmentation 412
19.15 Conceptual Address Domains 413
19.16 Linux, Windows And Mac Versions Of NAT 413
19.17 Overlay Networks 413
19.18 Multiple Simultaneous Overlays 415
19.19 Summary 415
Chapter 20 Client-Server Model Of Interaction 419
20.1 Introduction 419
20.2 The Client-Server Model 420
20.3 A Trivial Example: UDP Echo Server 420
20.4 Time And Date Service 422
20.5 Sequential And Concurrent Servers 423
20.6 Server Complexity 425
20.7 Broadcasting Requests 426
20.8 Client-Server Alternatives And Extensions 426
20.9 Summary 428
Chapter 21 The Socket API 431
21.1 Introduction 431
21.2 Versions Of The Socket API 432
21.3 The UNIX I/O Paradigm And Network I/O 432
21.4 Adding Network I/O to UNIX 432
21.5 The Socket Abstraction And Socket Operations 433
21.6 Obtaining And Setting Socket Options 438
21.7 How A Server Accepts TCP Connections 439
21.8 Servers That Handle Multiple Services 440
21.9 Obtaining And Setting The Host Name 441
21.10 Library Functions Related To Sockets 442
21.11 Network Byte Order And Conversion Routines 443
21.12 IP Address Manipulation Routines 444
21.13 Accessing The Domain Name System 444
21.14 Obtaining Information About Hosts 446
21.15 Obtaining Information About Networks 447
21.16 Obtaining Information About Protocols 447
21.17 Obtaining Information About Network Services 447
21.18 An Example Client 448
21.19 An Example Server 453
21.20 Summary 460
Chapter 22 Bootstrap And Autoconfiguration (DHCP, NDP or IPv6-ND) 463
22.1 Introduction 463
22.2 History Of IPv4 Bootstrapping 464
22.3 Using IP To Determine An IP Address 464
22.4 DHCP Retransmission And Randomization 465
22.5 DHCP Message Format 465
22.6 The Need For Dynamic Configuration 468
22.7 DHCP Leases And Dynamic Address Assignment 469
22.8 Multiple Addresses And Relays 469
22.9 DHCP Address Acquisition States 470
22.10 Early Lease Termination 471
22.11 Lease Renewal States 472
22.12 DHCP Options And Message Type 473
22.13 DHCP Option Overload 474
22.14 DHCP And Domain Names 474
22.15 Managed And Unmanaged Configuration 474
22.16 Managed And Unmanaged Configuration For IPv6 475
22.17 IPv6 Configuration Options And Potential Conflicts 476
22.18 IPv6 Neighbor Discovery Protocol (NDP) 477
22.19 ICMPv6 Router Solicitation Message 478
22.20 ICMPv6 Router Advertisement Message 478
22.21 ICMPv6 Neighbor Solicitation Message 479
22.22 ICMPv6 Neighbor Advertisement Message 480
22.23 ICMPv6 Redirect Message 480
22.24 Summary 481
Chapter 23 The Domain Name System (DNS) 485
23.1 Introduction 485
23.2 Names For Computers 486
23.3 Flat Namespace 486
23.4 Hierarchical Names 487
23.5 Delegation Of Authority For Names 488
23.6 Subset Authority 488
23.7 Internet Domain Names 489
23.8 Top-Level Domains 490
23.9 Name Syntax And Type 492
23.10 Mapping Domain Names To Addresses 493
23.11 Domain Name Resolution 495
23.12 Efficient Translation 496
23.13 Caching: The Key To Efficiency 497
23.14 Domain Name System Message Format 498
23.15 Compressed Name Format 501
23.16 Abbreviation Of Domain Names 501
23.17 Inverse Mappings 502
23.18 Pointer Queries 503
23.19 Object Types And Resource Record Contents 504
23.20 Obtaining Authority For A Subdomain 505
23.21 Server Operation And Replication 505
23.22 Dynamic DNS Update And Notification 506
23.23 DNS Security Extensions (DNSSEC) 506
23.24 Multicast DNS And Service Discovery 507
23.25 Summary 508
Chapter 24 Electronic Mail (SMTP, POP, IMAP, MIME) 511
24.1 Introduction 511
24.2 Electronic Mail 511
24.3 Mailbox Names And Aliases 512
24.4 Alias Expansion And Mail Forwarding 513
24.5 TCP/IP Standards For Electronic Mail Service 514
24.6 Simple Mail Transfer Protocol (SMTP) 515
