计算机网络与因特网PDF电子书下载

Chapter 1 Introduction 1

1．1 Growth Of Computer Networking 1

1．1 Growth Of Computer Networking 1

Chapter Contents 1

1．2 Complexity in Network Systems 2

1．3 Mastering The Complexity 2

1．3 Mastering The Complexity 2

1．2 Complexity In Network Systems 2

1．4 Concepts And Terminology 3

1．5 Organization Of The Text 3

1．5 Organization Of The Text 3

1．4 Concepts And Terminology 3

1．6 Summary 4

1．6 Summary 4

7．8 An Example Frame Format 7

2．2 Copper Wires 7

2．1 Introduction 7

Chapter 2 Transmission Media 7

PART 1 Data Transmission 7

2．3 Glass Fibers 9

2．4 Radio 10

2．5 Microwave 10

2．8 Summary 12

2．7 Laser 12

2．6 Infrared 12

3．1 Introduction 15

Chapter 3 Local Asynchronous Communication (RS-232) 15

3．3 Using Electric Current To Send Bits 16

3．2 The Need For Asynchronous Communication 16

3．5 Asynchronous Character Transmission With RS-232 17

3．4 Standards For Communication 17

3．6 Baud Rate, Framing , And Errors 19

3．7 Full Duplex Asynchronous Communication 20

3．9 Hardware Bandwidth And The Transmission Of Bits 21

3．8 Limitations Of Real Hardware 21

3．10 Summary 22

Chapter 4 Long-Distance Communication (Carriers And Modems) 25

4．1 Introduction 25

4．2 Sending Signals Across Long Distances 25

4．3 Modem Hardware Used For Modulation And Demodulation 28

4．5 Optical, Radio,And Dialup Modems 29

4．4 Leased Serial Data Circuits 29

4．6 Carrier Frequencies And Multiplexing 31

4．8 Summary 33

4．7 Time Division Multiplexing 33

PARTⅡ Packet Transmission 37

Chapter 5 Packets, Frames, And Error Detection 37

5．1 Introduction 37

5．2 The Concept Of Packets 37

5．3 Packets And Time-Division Multiplexing 39

5．4 Packets And Hardware Frames 40

5．5 Byte Stuffing 41

5．6 Transmission Errors 43

5．7 Parity Bits And Parity Checking 43

5．8 Probability,Mathematics,And Error Detection 44

5．9 Detecting Errors With Checksums 45

5．10 Detecting Errors With Cyclic Redundancy Checks 46

5．11 Combining Building Blocks 47

5．13 Summary 49

5．12 Frame Format And Error Detection Mechanisms 49

6．2 Direct Point-to-Point Communication 53

Chapter 6 LAN Technologies And Network Topology 53

6．1 Introduction 53

6．3 Shared Communication Channels 55

6．4 Significance Of LANs And locality Of Reference 56

6．5 LAN Topologies 57

6．6 Example Bus Network : Ethernet 59

6．7 Carrier Sense On Multi-Access Networks(CSMA) 60

6．8 Collision Detection And Backoff(CSMA/CD) 61

6．9 Another Example Bus Network :LocalTalk 62

6．10 Example Ring Network :IBM Token Ring 63

6．11 Another Example Ring Network :FDDI 64

6．12 Example Star Network :ATM 66

6．13 Summary 67

7．1 Introduction 71

Chapter 7 Hardware Addressing And Frame Type Identification 71

7．3 How LAN Hardware Uses Addresses To Filter Packets 72

7．2 Specifying A Recipient 72

7．4 Format Of A Physical Address 74

7．5 Broadcasting And A Broadcast Address 75

7．7 Frame Headers And Frame Format 76

7．6 Identifying Packet Contents 76

7．9 Using Networks That Do Not Have Self-identifying Frames 78

7．10 Network Analyzers, Physical Addresses,Frame Types 80

7．11 Summary 82

7．12 Ethernet Address Assignment 83

8．2 Speeds Of LANs And Computers 85

Chapter 8 LAN Wiring , Physical Topology , And Interface Hardware 85

8．1 Introduction 85

8．3 Network Interface Hardware 86

8．4 The Connection Between A NIC And A Network 88

8．5 Original Thick Ethernet Wiring 88

8．6 Connection Multiplexing 90

8．7 Thin Ethernet Wiring 91

8．8 Twisted Pair Ethernet 92

8．9 Advantages And Disadvantages Of Wiring Schemes 94

8．11 Network Interface Cards And Wiring Schemes 96

8．10 The Topology Paradox 96

8．12 Wiring Schemes And Other Network Technologies 98

8．13 Summary 99

9．2 Distance Limitation And LAN Design 101

9．1 Introduction 101

Chapter 9 Extending LANs : Fiber Modems, Repeaters,Bridges ,and Switches 101 101

9．3 Fiber Optic Extensions 102

9．4 Repeaters 103

9．5 Bridges 106

9．6 Frame Filtering 107

9．8 Planning A Bridged Network 108

9．7 Startup And Steady State Behavior of Bridged Networks 108

9．9 Bridging Between Buildings 109

9．10 Bridging Across Longer Distances 110

9．11 A Cycle Of Bridges 112

9．12 Distributed Spanning Tree 113

9．13 Switching 113

9．14 Combining Switches And Hubs 114

9．16 Summary 115

9．15 Bridging And Switching With Other Technologies 115

Chapter 10 WAN Technologies And Routing 119

10．1 Introduction 119

10．2 Large Networks And Wide Areas 119

10．3 Packet Switches 120

10．4 Forming A WAN 121

10．5 Store And Forward 122

10．6 Physical Addressing In A WAN 123

10．7 Next-Hop Forwarding 123

10．8 Source Independence 125

10．9 Relationship Of Hierarchical Addresses To Routing 125

10．10 Routing In A WAN 126

10．11 Use Of Default Routes 128

10．13 Shortest Path Computation In A Graph 129

10．12 Routing Table Computation 129

10．15 Vector Distance Routing 132

10．14 Distributed Route Computation 132

10．17 Example WAN Technologies 134

10．16 Link-State Routing(SPF ) 134

10．18 Summary 137

Chapter 11 Network Ownership, Service Paradlgm, And Performance 141

11．1 Introduction 141

11．2 Network Ownership 142

11．3 Service Paradigm 143

11．4 Connection Duration And Persistence 144

11．5 Examples of Service Paradigms 146

11．6 Addresses And Connection Identifiers 147

11．7 Network Performance Characteristics 148

11．8 Summary 151

12．2 The Need For Protocols 155

12．1 Introduction 155

Chapter 12 Protocois And Layering 155

12．3 Protocol Suites 156

12．5 The Seven Layers 157

12．4 A Plan For Protocol Design 157

12．6 Stacks : Layered Software 159

12．7 How Layered Software Works 160

12．9 The Scientific Basis For Layering 161

12．8 Multiple,Nested Headers 161

12．10 Techniques Protocols Use 162

12．11 The Art Of Protocol Design 170

12．12 Summary 171

PARTⅢ Internetworking 175

13．2 The Motivation For Internetworking 175

13．1 Introduction 175

Chapter 13 Internetworking : Concepts, Architecture,and Protocols 175

13．4 Universal Service In A Heterogeneous World 176

13．3 The Concept Of Universal Service 176

13．6 Physical Network Connection With Routers 177

13．5 Internetworking 177

13．7 Internet Architecture 178

13．8 Achieving Universal Service 179

13．9 A Virtual Network 179

13．11 Significance Of Internetworking And TCP/IP 181

13．10 Protocols For Internetworking 181

13．12 Layering And TCP/IP Protocols 182

13．13 Host Computers, Routers, And Protocol Layers 183

13．14 Summary 184

14．2 Addresses For The Virtual Internet 187

Chapter 14 IP : Internet Protocol Addresses 187

14．1 Introduction 187

14．3 The IP Addressing Scheme 188

14．4 The IP Address Hierarchy 189

14．5 Classes Of IP Addresses 189

14．6 Computing The Class of An Address 191

14．7 Dotted Decimal Notation 192

14．8 Classes And Dotted Decimal Notation 192

14．9 Division Of The Address Space 193

14．11 An Addressing Example 194

14．10 Authority For Addresses 194

14．12 Special IP Addresses 195

14．13 Summary Of Special IP Addresses 197

14．15 Routers And The IP Addressing Principle 198

14．14 The Berkeley Broadcast Address Form 198

14．16 Multi-Homed Hosts 199

14．17 Summary 200

15．1 Introduction 203

Chapter 15 Binding Protocol Addresses(ARP) 203

15．2 Protocol Addresses And Packet Delivery 204

15．3 Address Resolution 204

15．4 Address Resolution Techniques 205

15．5 Address Resolution With Table Lookup 206

15．6 Address Resolution With Closed-Form Computation 207

15．7 Address Resolution With Message Exchange 208

15．8 Address Resolution Protocol 209

15．9 ARP Message Delivery 210

15．10 ARP Message Format 211

15．11 Sending An ARP Message 212

15．12 Identifying ARP Frames 213

15．14 Processing An Incoming ARP Message 213

15．13 Caching ARP Responses 213

15．15 Layering, Address Resolution,Protocol Addresses 214

15．16 Summary 215

16．1 Introduction 219

16．2 Connectionless Service 219

Chapter 16 IP Datagrams And Datagram Forwarding 219

16．3 Virtual Packets 220

16．4 The IP Datagram 221

16．5 Forwarding An IP Datagram 222

16．6 IP Addresses And Routing Table Entries 223

16．8 Destination And Next-Hop Addresses 224

16．7 The Mask Field And Datagram Forwarding 224

16．9 Best-Effort Delivery 225

16．10 The IP Datagram Header Format 226

16．11 Summary 227

Chapter 17 IP Encapsulation,Fragmentation,And Reassembly 229

17．2 Datagram Transmission And Frames 229

17．1 Introduction 229

17．3 Encapsulation 230

17．4Transmission Across An Internet 231

17．5 MTU,Datagram Size, And Encapsulation 232

17．6 Reassembly 234

17．7 Identifying A Datagram 234

17．9 Fragmenting A Fragment 235

17．8 Fragment Loss 235

17．10 Summary 236

18．2 The Success Of IP 239

18．1 Introduction 239

Chapter 18 The Future IP(Ipv6) 239

18．3 The Mot?vation For Change 240

18．4 A Name And A Version Number 241

18．5 Characterization Of Features In Ipv6 241

18．6 IPv6 Datagram Format 242

18．7 IPv6 Base Header Format 242

18．8 How IPv6 Handles Multiple Headers 244

18．9 Fragmentation, Reassembly,And Path MTU 245

18．10 The Purpose Of Multiple Headers 246

18．11 IPv6 Addressing 247

18．13 Summary 248

18．12 IPv6 Colon Hexadecimal Notation 248

Chapter 19 An Error Reporting Mechanism(ICMP) 251

19．1 Introduction 251

19．2 Best-Effort Semantics And Error Detection 251

19．3 Internet Control Message Protocol 252

19．4 ICMP Message Transport 254

19．6 Using ICMP To Trace A Route 255

19．5 Using ICMP Messages To Test Reachability 255

19．7 Using ICMP For Path MTU Discovery 256

19．8 Summary 257

20．2 The Need For Reliable Transport 259

20．1 Introduction 259

Chapter 20 TCP : Reliable Transport Service 259

20．3 The Transmission Control Protocol 260

20．4 The Service TCP Provides To Applications 260

20．5 End-To-End Service And Datagrams 261

20．6 Achieving Reliability 262

20．7 Packet Loss And Retransmission 263

20．8 Adaptive Retransmission 264

20．10 Buffers．Flow Control,And Windows 265

20．9 Compar?son Of Retransmission Times 265

20．11 Three-Way Handshake 267

20．12 Congestion Control 268

20．13 TCP Segment Format 268

20．14 Summary 269

Chapter 21 Client-Server interaction 273

PART Ⅳ Network Applications 273

21．1 Introduction 273

21．2 The Functionality Application Software Provides 274

21．3 The Functionality An Internet Provides 274

21．4 Making Contact 275

21．5 The Client-Server Paradigm 275

21．6 Characteristics Of Clients And Servers 275

21．8 Requests, Responses,And Direction Of Data Flow 276

21．7 Server Programs And Server-Class Computers 276

21．9 Transport Protocols and Client-Server Interaction 277

21．10 Multiple Services On One Computer 278

21．11 Identifying A Particular Service 279

21．12 Multiple Copies of A Server For A Single Service 279

21．13 Dynamic Server Creation 280

21．14 Transport Protocols And Unambiguous Communication 280

21．15 Connection-Oriented And Connectionless Transport 281

21．16 A Service Reachable Through Multiple Protocols 282

21．17 Complex Client-Server Interactions 282

21．18 Interactions And Circular Dependencies 283

21．19 Summary 283

22．2 Application Program Interface 285

22．1 Introduction 285

Chapter 22 The Socket Interface 285

22．3 The Socket API 286

22．4 Sockets And Socket Libraries 286

22．5 Socket Communication And UNIX I/O 287

22．6 Sockets, Descriptors, And Network I/O 288

22．7 Parameters And The Socket API 288

22．8 Procedures That Implement The Socket API 289

22．9 Read And Write With Sockets 295

22．10 Other Socket Procedures 295

22．11 Sockets,Threads,And Inheritance 296

22．12 Summary 296

23．2 Connection-Oriented Communication 299

23．1 Introduction 299

Chapter 23 Example Of A Client And A Server 299

23．5 Sequence Of Socket Procedure Calls 300

23．4 Command-Line Arguments For The Example Programs 300

23．3 An Example Service 300

23．6 Code For Example Client 302

23．7 Code For Example Server 305

23．8 Stream Service And Multiple Recv Calls 307

23．9 Socket Procedures And Blocking 308

23．10 Size Of The Code And Error Reporting 308

23．11 Using The Example Client With Another Service 309

23．12 Using Another Client To Test The Server 309

23．13 Summary 310

24．1 Introduction 313

Chapter 24 Naming With The Domain Name System 313

24．2 Structure Of Computer Names 314

24．3 Geographic Structure 315

24．4 Domain Names Within An Organization 316

24．5 The DNS Client-Server Model 318

24．6 The DNS Server Hierarchy 318

24．8 Locality Of Reference And Multiple Servers 320

24．7 Server Architectures 320

24．10 Resolving A Name 321

24．9 Links Among Servers 321

24．12 Types Of DNS Entries 323

24．11 Optimization Of DNS Performance 323

24．13 Aliases Using The CNAME Type 324

24．14 An Important Consequence Of Multiple Types 324

24．16 Summary 325

24．15 Abbreviations And The DNS 325

25．2 The Electronic Mail Paradigm 329

25．1 Introduction 329

Chapter 25 Eiectronic Mail Representation And Transfer 329

25．3 Electronic Mailboxes And Addresses 330

25．4 Electronic Mail Message Format 331

25．5 Carbon Copies 333

25．6 Multipurpose Internet Mail Extensions 333

25．8 Mail Transfer 335

25．7 E-mail And Application Programs 335

25．9 The Simple Mail Transfer Protocol 336

25．10 Optimizing For Multiple Recipients On A Computer 336

25．11 Mail Exploders, Lists ,And Forwarders 336

25．12 Mail Gateways 337

25．13 Automated Mailing Lists 338

25．14 Mail R?lays And E-mail Addresses 339

25．15 Mailbox Access 340

25．16 Dialup Connections And POP 342

25．17 Summary 342

Chapter 26 File Transfer And Remote File Access 345

26．1 Introduction 345

26．2 Data Transfer And Distributed Computation 345

26．4 Generalized File Transfer 346

26．3 Saving Intermediate Results 346

26．5 Interactive And Batch Transfer Paradigms 347

26．7 FTP General Model And User Interface 348

26．6 The File Transfer Protocol 348

26．8 FTP Commands 349

26．9 Connections , Authorization, And File Permissions 350

26．11File Transfer In Either Direction 351

26．10 Anonymous File Access 351

26．14 Changing Directories And Listing Contents 352

26．12 Wildcard Expansion In File Names 352

26．13 File Name Translation 352

26．15 File Types And Transfer Modes 353

26．16 Example Of Using FTP 354

26．18 Client-Server Interaction In FTP 356

26．17 Verbose Output 356

26．19 Control And Data Connections 356

26．20 Data Connections And End Of File 357

26．22 Network File System 358

26．21 Trivial File Transfer Protocol 358

26．23 Summary 359

27．2 Browser interface 363

Chapter 27 World Wide Web Pages And Browsing 363

27．1 Introduction 363

27．3 Hypertext And Hypermedia 364

27．4 Document Representation 364

27．5 HTML Format And Representation 365

27．7 Headings 367

27．6 Example HTML Formatting Tags 367

27．9 Embedding Graphics Images in A Web Page 368

27．8 Lists 368

27．10 Identifying A Page 369

27．11 Hypertext Links From One Document To Another 370

27．12 Client-Server Interaction 371

27．13 Web Document Transport And HTTP 372

27．14 Browser Architecture 372

27．15 Optional Clients 373

27．16 Caching In Web Browsers 374

27．27 Summary 375

Chapter 28 CGI Technology For Dynamic Web Documents 379

28．1 Introduction 379

28．2 Three Basic Types of Web Documents 380

28．3 Advantages And Disadvantages Of Each Document Type 380

28．4 Implementation Of Dynamic Documents 382

28．5 The CGI Standard 383

28．6 Output From A CGI Program 383

28．7 An Example CGI Program 384

28．8 Parameters And Environment Variables 386

28．10 A CGI Script With Long-Term State Information 387

28．9 State Information 387

28．11 A CGI Script With Short-Term State Information 389

28．12 Forms And Interaction 392

28．13 Summary 392

29．1 Introduction 395

Chapter 29 Java Technology For Active Web Documents 395

29．2 An Early Form of Continuous Update 396

29．3 Active Documents And Server Overhead 397

29．4 Active Document Representation And Translation 397

29．5 Java Technology 399

29．6 The Java Programming Language 399

29．7 The Java Run-Time Environment 401

29．8 The Java Library 402

29．9 A Graphics Toolkit 403

29．10 Using Java Graphics on A Particular Computer 404

29．12 Compiling A Java Program 405

29．11 Java Interpreters And Browsers 405

29．13 An Example Applet 406

29．14 Invoking An Applet 408

29．15 Example Of Interaction With A Browser 409

29．16 Errors And Exception Handling 411

29．17 Alternatives And Variations 411

29．18 Summary 412

Chapter 30 Network Management(SNMP) 415

30．1 Introduction 415

30．2 Managing An Internet 415

30．3 The Danger Of Hidden Failures 416

30．4 Network Management Software 417

30．5 Clients, Servers, Managers,And Agents 417

30．6 Simple Network Management Protocol 418

30．7 Fetch-Store Paradigm 418

30．8 The MIB And Object Names 419

30．10 MIB Variables That Correspond To Arrays 420

30．9 The Variety Of MIB Variables 420

30．11 Summary 421

31．2 Secure Networks And Policies 423

Chapter 31 Network Security 423

31．1 Introductionk 423

31．3 Aspects Of Security 424

31．5 Integrity Mechanisms 425

31．4 Responsibility And Control 425

31．7 Encryption And Privacy 426

31．6 Access Control And Passwords 426

31．9 Authentication With Digital Signatures 427

31．8 Public Key Encryption 427

31．10 Packet Filtering 428

31．11 Internet Firewall Concept 430

31．12 Summary 431

Chapter 32 Initialization (Configuration) 433

32．2 Bootstrapping 433

32．1 Introduction 433

32．3 Starting Protocol Software 434

32．4 Protocol Parameters 434

32．6 Examples Of Items That Need To Be Configured 435

32．5 Protocol Configuration 435

32．7 Example Configuration : Using A Disk File 436

32．8 The Need To Automate Protocol Configuration 437

32．9 Methods For Automated Protocol Configuration 437

32．10 The Address Used To Find An Address 438

32．11 A Sequence Of Protocols Used During Bootstrap 439

32．12 Bootstrap Protocol(BOOTP) 439

32．13 Automatic Address Assignment 441

32．15 Optimizations In DHCP 442

32．14 Dynamic Host Configuration Protocol(DHCP) 442

32．16 DHCP Message Format 443

32．18 Summary 444

32．17 DHCP And Domain Names 444

Appendix 1 Glossary Of Networking Terms And Abbreviations 447

Appendix 2 The ASCII Character Set 477

Appendix3 How To Use The CD-ROM Included With This Book 479

Bibliography 485

Index 495