Table of Contents Chapter 1 Computer Networks and the Internet 1 1.1 What Is the Internet? 2 1.1.1 A Nuts-and-Bolts Description 2 1.1.2 A Services Description 5 1.1.3 What Is a Protocol? 7 1.2 The Network Edge 9 1.2.1 Access Networks 12 1.2.3 Physical Media 18 1.3 The Network Core 22 1.3.1 Packet Switching 22 1.3.2 Circuit Switching 27 1.3.3 A Network of Networks 32 1.4 Delay, Loss, and Throughput in Packet-Switched Networks 35 1.4.1 Overview of Delay in Packet-Switched Networks 35 1.4.2 Queuing Delay and Packet Loss 39 1.4.3 End-to-End Delay 42 1.4.4 Throughput in Computer Networks 44 1.5 Protocol Layers and Their Service Models 47 1.5.1 Layered Architecture 47 1.5.2 Encapsulation 53 1.6 Networks Under Attack 55 1.7 History of Computer Networking and the Internet 60 1.7.1 The Development of Packet Switching: 1961—1972 60 1.7.2 Proprietary Networks and Internetworking: 1972—1980 62 1.7.3 A Proliferation of Networks: 1980—1990 63 1.7.4 The Internet Explosion: The 1990s 64 1.7.5 The New Millennium 65 1.8 Summary 66 Homework Problems and Questions 68 Problems 70 Wireshark Lab 78 Interview: Leonard Kleinrock 80 Chapter 2 Application Layer 83 2.1 Principles of Network Applications 84 2.1.1 Network Application Architectures 86 2.1.2 Processes Communicating 88 2.1.3 Transport Services Available to Applications 91 2.1.4 Transport Services Provided by the Internet 93 2.1.5 Application-Layer Protocols 96 2.1.6 Network Applications Covered in This Book 97 2.2 The Web and HTTP 98 2.2.1 Overview of HTTP 98 2.2.2 Non-Persistent and Persistent Connections 100 2.2.3 HTTP Message Format 103 2.2.4 User-Server Interaction: Cookies 108 2.2.5 Web Caching 110 2.2.6 The Conditional GET 114 2.3 File Transfer: FTP 116 2.3.1 FTP Commands and Replies 118 2.4 Electronic Mail in the Internet 118 2.4.1 SMTP 121 2.4.2 Comparison with HTTP 124 2.4.3 Mail Message Format 125 2.4.4 Mail Access Protocols 125 2.5 DNS–The Internet’s Directory Service 130 2.5.1 Services Provided by DNS 131 2.5.2 Overview of How DNS Works 133 2.5.3 DNS Records and Messages 139 2.6 Peer-to-Peer Applications 144 2.6.1 P2P File Distribution 145 2.6.2 Distributed Hash Tables (DHTs) 151 2.6.3 Case Study: P2P Internet Telephony with Skype 158 2.7 Socket Programming: Creating Network Applications 156 2.7.1 Socket Programming with UDP 157 2.7.2 Socket Programming with TCP 163 2.8 Summary 168 Homework Problems and Questions 169 Problems 171 Socket Programming Assignments 179 Wireshark Labs 181 Interview: Bram Cohen 182 Chapter 3 Transport Layer 185 3.1 Introduction and Transport-Layer Services 186 3.1.1 Relationship Between Transport and Network Layers 186 3.1.2 Overview of the Transport Layer in the Internet 189 3.2 Multiplexing and Demultiplexing 191 3.3 Connectionless Transport: UDP 198 3.3.1 UDP Segment Structure 202 3.3.2 UDP Checksum 202 3.4 Principles of Reliable Data Transfer 204 3.4.1 Building a Reliable Data Transfer Protocol 206 3.4.2 Pipelined Reliable Data Transfer Protocols 215 3.4.3 Go-Back-N (GBN) 218 3.4.4 Selective Repeat (SR) 223 3.5 Connection-Oriented Transport: TCP 230 3.5.1 The TCP Connection 231 3.5.2 TCP Segment Structure 233 3.5.3 Round-Trip Time Estimation and Timeout 238 3.5.4 Reliable Data Transfer 242 3.5.5 Flow Control 250 3.5.6 TCP Connection Management 252 3.6 Principles of Congestion Control 259 3.6.1 The Causes and the Costs of Congestion 259 3.6.2 Approaches to Congestion Control 265 3.6.3 Network-Assisted Congestion-Control Example: ATM ABR Congestion Control 266 3.7 TCP Congestion Control 269 3.7.1 Fairness 279 3.8 Summary 283 Homework Problems and Questions 285 Problems 288 Programming Assignments 300 Wireshark Lab: Exploring TCP 301 Wireshark Lab: Exploring UDP 301 Interview: Sally Floyd 302 Chapter 4 The Network Layer 305 4.1 Introduction 306 4.1.1 Forwarding and Routing 308 4.1.2 Network Service Models 310 4.2 Virtual Circuit and Datagram Networks 313 4.2.1 Virtual-Circuit Networks 314 4.2.2 Datagram Networks 317 4.2.3 Origins of VC and Datagram Networks 319 4.3 What’s Inside a Router? 320 4.3.1 Input Processing 322 4.3.2 Switching 324 4.3.3 Output Processing 326 4.3.4 Where Does Queuing Occur? 327 4.3.5 The Routing Control Plane 331 4.4 The Internet Protocol (IP): Forwarding and Addressing in the Internet 331 4.4.1 Datagram Format 332 4.4.2 IPv4 Addressing 338 4.4.3 Internet Control Message Protocol (ICMP) 353 4.4.4 IPv6 356 4.4.5 A Brief Introduction into IP Security 362 4.5 Routing Algorithms 363 4.5.1 The Link-State (LS) Routing Algorithm 366 4.5.2 The Distance-Vector (DV) Routing Algorithm 371 4.5.3 Hierarchical Routing 379 4.6 Routing in the Internet 383 4.6.1 Intra-AS Routing in the Internet: RIP 384 4.6.2 Intra-AS Routing in the Internet: OSPF 388 4.6.3 Inter-AS Routing: BGP 390 4.7 Broadcast and Multicast Routing 399 4.7.1 Broadcast Routing Algorithms 400 4.7.2 Multicast 405 4.8 Summary 412 Homework Problems and Questions 413 Problems 416 Socket Programming Assignment 428 Programming Assignment 429 Wireshark Labs 430 Interview: Vinton G. Cerf 431 Chapter 5 The Link Layer: Links, Access Networks, and LANs 433 5.1 Introduction to the Link Layer 434 5.1.1 The Services Provided by the Link Layer 436 5.1.2 Where Is the Link Layer Implemented? 437 5.2 Error-Detection and -Correction Techniques 438 5.2.1 Parity Checks 440 5.2.2 Checksumming Methods 442 5.2.3 Cyclic Redundancy Check (CRC) 443 5.3 Multiple Access Links and Protocols 445 5.3.1 Channel Partitioning Protocols 448 5.3.2 Random Access Protocols 449 5.3.3 Taking-Turns Protocols 459 5.3.4 DOCSIS: The Link-Layer Protocol for Cable Internet Access 460 5.4 Switched Local Area Networks 461 5.4.1 Link-Layer Addressing and ARP 462 5.4.2 Ethernet 469 5.4.3 Link-Layer Switches 476 5.4.4 Virtual Local Area Networks (VLANs) 482 5.5 Link Virtualization: A Network as a Link Layer 486 5.5.1 Multiprotocol Label Switching (MPLS) 487 5.6 Data Center Networking 490 5.7 Retrospective: A Day in the Life of a Web Page Request 495 5.7.1 Getting Started: DHCP, UDP, IP, and Ethernet 495 5.7.2 Still Getting Started: DNS, ARP 497 5.7.3 Still Getting Started: Intra-Domain Routing to the DNS Server 498 5.7.4 Web Client-Server Interaction: TCP and HTTP 499 5.8 Summary 500 Homework Problems and Questions 502 Problems 503 Wireshark Labs 510 Interview: Simon S. Lam 511 Chapter 6 Wireless and Mobile Networks 513 6.1 Introduction 514 6.2 Wireless Links and Network Characteristics 519 6.2.1 CDMA 522 6.3 WiFi: 802.11 Wireless LANs 526 6.3.1 The 802.11 Architecture 527 6.3.2 The 802.11 MAC Protocol 531 6.3.3 The IEEE 802.11 Frame 537 6.3.4 Mobility in the Same IP Subnet 541 6.3.5 Advanced Features in 802.11 542 6.3.6 Personal Area Networks: Bluetooth and Zipbee 544 6.4 Cellular Internet Access 546 6.4.1 An Overview of Cellular Network Architecture 547 6.4.2 3G Cellular Data Networks: Extending the Internet to Cellular Subscribers 550 6.4.3 On to 4G: LTE 553 6.5 Mobility Management: Principles 555 6.5.1 Addressing 557 6.5.2 Routing to a Mobile Node 559 6.6 Mobile IP 564 6.7 Managing Mobility in Cellular Networks 570 6.7.1 Routing Calls to a Mobile User 571 6.7.2 Handoffs in GSM 572 6.8 Wireless and Mobility: Impact on Higher-Layer Protocols 575 6.9 Summary 578 Homework Problems and Questions 578 Problems 580 Wireshark Labs 583 Interview: Deborah Estrin 584 Chapter 7 Multimedia Networking 587 7.1 Multimedia Networking Applications 588 7.1.1 Properties of Video 588 7.1.2 Properties of Audio 590 7.1.3 Types of Multimedia Network Applications 591 7.2 Streaming Stored Video 593 7.2.1 UDP Streaming 595 7.2.2 HTTP Streaming 596 7.2.3 Adaptive Streaming and DASH 600 7.2.4 Content Distribution Networks 602 7.2.5 Case Studies: Netflix, YouTube, and KanKan 608 7.3 Voice-over-IP 612 7.3.1 Limitations of the Best-Effort IP Service 612 7.3.2 Removing Jitter at the Receiver for Audio 614 7.3.3 Recovering from Packet Loss 618 7.3.4 Case Study: Internet Telephony with Skype 621 7.4 Protocols for Real-Time Interactive Applications 623 7.4.1 RTP 623 7.4.2 SIP 626 7.5 Network Support for Multimedia 632 7.5.1 Dimensioning Best-Effort Networks 634 7.5.2 Providing Multiple Classes of Service 636 7.5.3 Diffserv 648 7.5.4 Per-Connection Quality-of-Service (QoS) Guarantees: Resource Reservation and Call Admission 652 7.6 Summary 655 Homework Problems and Questions 656 Problems 658 Programming Assignment 666 Interview: Henning Schulzrinne 668 Chapter 8 Security in Computer Networks 671 8.1 What Is Network Security? 672 8.2 Principles of Cryptography 675 8.2.1 Symmetric Key Cryptography 676 8.2.2 Public Key Encryption 683 8.3 Message Integrity and Digital Signatures 688 8.3.1 Cryptographic Hash Functions 689 8.3.2 Message Authentication Code 691 8.3.3 Digital Signatures 693 8.4 End-Point Authentication 700 8.4.1 Authentication Protocol ap1.0 700 8.4.2 Authentication Protocol ap2.0 701 8.4.3 Authentication Protocol ap3.0 701 8.4.4 Authentication Protocol ap3.1 703 8.4.5 Authentication Protocol ap4.0 703 8.5 Securing E-mail 705 8.5.1 Secure E-mail 706 8.5.2 PGP 710 8.6 Securing TCP Connections: SSL 711 8.6.1 The Big Picture 713 8.6.2 A More Complete Picture 716 8.7 Network-Layer Security: IPsec and Virtual Private Networks 718 8.7.1 IPsec and Virtual Private Networks (VPNs) 718 8.7.2 The AH and ESP Protocols 720 8.7.3 Security Associations 720 8.7.4 The IPsec Datagram 721 8.7.5 IKE: Key Management in IPsec 725 8.8 Securing Wireless LANs 726 8.8.1 Wired Equivalent Privacy (WEP) 726 8.8.2 IEEE802.11i 728 8.9 Operational Security: Firewalls and Intrusion Detection Systems 731 8.9.1 Firewalls 731 8.9.2 Intrusion Detection Systems 739 8.10 Summary 742 Homework Problems and Questions 744 Problems 746 Wireshark Lab 752 IPsec Lab 752 Interview: Steven M. Bellovin 753 Chapter 9 Network Management 755 9.1 What Is Network Management? 756 9.2 The Infrastructure for Network Management 760 9.3 The Internet-Standard Management Framework 764 9.3.1 Structure of Management Information: SMI 766 9.3.2 Management Information Base: MIB 770 9.3.3 SNMP Protocol Operations and Transport Mappings 772 9.3.4 Security and Administration 775 9.4 ASN.1 778 9.5 Conclusion 783 Homework Problems and Questions 783 Problems 784 Interview: Jennifer Rexford 786 References 789 Index 823