COMPUTER AND COMMUNICATION NETWORKS Nader F. Mir Upper Saddle River, NJ . Boston . Indianapolis . San Francisco . New York Toronto . Montreal . London . Munich . Paris . Madrid . Capetown Sydney . Tokyo . Singapore . Mexico City Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim, the designations have been printed with initial capital letters or in all capitals. The author and publisher have taken care in the preparation of this book, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of the use of the information or programs contained herein. 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First printing, November 2006 Contents Preface xxi About the Author xxxi PART I: Fundamental Concepts 1 1 Packet-Switched Networks 3 1.1 Basic Definitions in Data Networks 4 1.1.1 Packet Switching versus Circuit Switching 4 1.1.2 Messages, Packets, and Frames 5 1.1.3 The Internet 6 1.1.4 ISPs and Internetwork Components 9 1.2 Types of Packet-Switched Networks 10 1.2.1 Connectionless Networks 11 1.2.2 Connection-Oriented Networks 13 1.3 Packet Size and Optimizations 14 1.4 Summary 16 1.5 Exercises 17 2 Foundation of Networking Protocols 19 2.1 5-Layer TCP/IP Model 20 2.2 7-Layer OSI Model 22 2.3 Internet Protocols and Addressing 23 2.3.1 IP Packet 23 2.3.2 IP Addressing Scheme 24 2.3.3 Subnet Addressing and Masking 25 viii Contents 2.3.4 Classless Interdomain Routing (CIDR) 27 2.3.5 Packet Fragmentation and Reassembly 28 2.3.6 Internet Control Message Protocol (ICMP) 29 2.3.7 IP Version 6 (IPv6) 30 2.4 Equal-Sized Packets Model: ATM 33 2.4.1 ATM Protocol Structure 34 2.4.2 ATM Cell Structure 36 2.5 Summary 39 2.6 Exercises 39 3 Networking Devices 43 3.1 Multiplexers 43 3.1.1 Frequency-Division Multiplexing (FDM) 44 3.1.2 Wavelength-Division Multiplexing (WDM) 44 3.1.3 Time-Division Multiplexing 45 3.2 Modems and Internet Access Devices 50 3.2.1 Line Coding Methods 50 3.2.2 Digital Modulation Techniques 52 3.2.3 Digital Subscriber Line (DSL) Modems 54 3.2.4 Cable Modems 56 3.3 Switching and Routing Devices 57 3.3.1 Repeaters, Hubs, and Bridges 57 3.3.2 Routers and Higher-Layer Switches 59 3.4 Router Structure 60 3.4.1 Input Port Processor (IPP) 60 3.4.2 Switch Fabric 63 3.4.3 Switch Controller 64 3.4.4 Output Port Processors (OPP) 65 3.5 Summary 67 3.6 Exercises 67 4 Data Links and Transmission 71 4.1 Data Links 72 4.2 Wired Links and Transmission 73 4.2.1 Twisted-Pair Links 73 4.2.2 Coaxial Cable 73 4.2.3 Optical Fiber 73 4.3 Wireless Links and Transmission 74 4.3.1 Choice of Antenna 75 Contents ix 4.3.2 Wireless Channels 76 4.3.3 Capacity Limits of Wireless Channels 79 4.3.4 Channel Coding 79 4.3.5 Flat-Fading Countermeasures 79 4.3.6 Intersymbol Interference Countermeasures 80 4.3.7 Orthogonal Frequency Division Multiplexing (OFDM) 81 4.4 Methods of Channel Access on Links 82 4.4.1 Frequency-Division Multiple Access 83 4.4.2 Time-Division Multiple Access 83 4.4.3 Code-Division Multiple Access 85 4.4.4 Space-Division Multiple Access 87 4.4.5 Hybrid Multiple-Access Techniques 87 4.5 Error Detection and Correction 87 4.5.1 Error Detection Methods 89 4.5.2 Cyclic Redundancy Check (CRC) Algorithm 89 4.6 Link-Level Flow Control 94 4.6.1 Stop-and-Wait Flow Control 95 4.6.2 Sliding-Window Flow Control 96 4.7 Summary 98 4.8 Exercises 99 5 Local Area Networks and Networks of LANs 101 5.1 LANs and Basic Topologies 102 5.2 LAN Protocols 103 5.2.1 Logical-Link Layer (LLC) 103 5.2.2 Medium Access Control (MAC) 104 5.3 MAC and IP Addresses 104 5.3.1 Address Resolution Protocol (ARP) 105 5.3.2 Reverse Address Resolution Protocol (RARP) 106 5.4 Classification of MAC Protocols 106 5.5 Contention-Access MAC 107 5.5.1 Carrier Sense Multiple Access (CSMA) 108 5.5.2 Ethernet LAN: IEEE 802.3 Standard 113 5.6 Round-Robin-Access MAC 114 5.6.1 Token-Ring Access Protocol 114 5.6.2 Token-Ring: IEEE 802.5 Standard 116 5.7 Network of LANs 116 5.7.1 Using Repeaters, Hubs, and Bridges 117 5.7.2 Layers 2 and 3 Switches 124 x Contents 5.8 Summary 125 5.9 Exercises 126 6 Wireless Networks and Mobile IP 129 6.1 Infrastructure of Wireless Networks 130 6.2 Wireless LAN Technologies 131 6.2.1 Infrared LANs 132 6.2.2 Spread-Spectrum LANs 133 6.2.3 Narrowband RF LANs 133 6.2.4 Home RF and Bluetooth 134 6.3 IEEE 802.11 Wireless Standard 134 6.3.1 802.11 Physical Layer 136 6.3.2 802.11 MAC Layer 137 6.3.3 WiFi Technology and 802.11 141 6.4 Cellular Networks 142 6.4.1 Connectivity 143 6.4.2 Frequency Reuse 146 6.4.3 Local and Regional Handoffs 149 6.4.4 Mobility Management 150 6.4.5 Generations of Cellular Systems 154 6.4.6 CDMA-Based Mobile Wireless 154 6.5 Mobile IP 155 6.5.1 Addresses and Agents 156 6.5.2 Agent Discovery Phase 157 6.5.3 Registration 158 6.5.4 Mobile IP Routing 159 6.5.5 Security 163 6.6 Wireless Mesh Networks (WMNs) 163 6.6.1 WiMAX Technology and IEEE 802.16 163 6.6.2 Applications of Mesh Networks 164 6.6.3 Physical and MAC Layers of WMNs 167 6.7 Summary 168 6.8 Exercises 168 7 Routing and Internetworking 171 7.1 Network-Layer Routing 172 7.1.1 Assigning Addresses to Hosts and Routers, and DHCP 173 7.1.2 Network Address Translation (NAT) 174 7.1.3 Route Cost 176 7.1.4 Classification of Routing Algorithms 176 Contents xi 7.2 Least-Cost-Path Algorithms 177 7.2.1 Dijkstra’s Algorithm 177 7.2.2 Bellman-Ford Algorithm 178 7.3 Non-Least-Cost-Path Routing 180 7.3.1 Flood Routing 180 7.3.2 Deflection Routing 181 7.4 Intradomain Routing Protocols 182 7.4.1 Routing Information Protocol (RIP) 183 7.4.2 Open Shortest Path First (OSPF) 187 7.5 Interdomain Routing Protocols 190 7.5.1 Border Gateway Protocol (BGP) 190 7.6 Congestion Control at Network Layer 194 7.6.1 Unidirectional Congestion Control 196 7.6.2 Bidirectional Congestion Control 197 7.6.3 Random Early Detection (RED) 198 7.6.4 A Quick Estimation of Link Blocking 200 7.7 Summary 202 7.8 Exercises 203 8 Transport and End-to-End Protocols 207 8.1 Transport Layer 208 8.1.1 Interaction of Transport and Network Layers 209 8.2 Transmission Control Protocol (TCP) 209 8.2.1 TCP Segment 210 8.2.2 Connection Setup 212 8.3 User Datagram Protocol (UDP) 213 8.3.1 UDP Segment 213 8.3.2 Applications of TCP and UDP 214 8.4 Mobile Transport Protocols 215 8.4.1 TCP for Mobility 215 8.4.2 UDP for Mobility 216 8.5 TCP Congestion Control 217 8.5.1 Additive Increase, Multiplicative Decrease Control 217 8.5.2 Slow Start Method 219 8.5.3 Fast Retransmit Method 220 8.5.4 TCP Congestion Avoidance Methods 221 8.6 Summary 222 8.7 Exercises 223 xii Contents 9 Applications and Network Management 225 9.1 Application-Layer Overview 226 9.1.1 Client and Server Model 226 9.2 Domain Name System (DNS) 227 9.2.1 Domain Name Space 228 9.2.2 Name/Address Mapping 230 9.2.3 DNS Message Format 231 9.3 Remote Login Protocols 232 9.3.1 TELNET Protocol 233 9.3.2 Secure Shell (SSH) Protocol 234 9.4 Electronic Mail (E-mail) 235 9.4.1 Simple Mail Transfer Protocol (SMTP) and E-mail 235 9.5 File Transfer and FTP 237 9.5.1 File Transfer Protocol (FTP) 237 9.5.2 Secure Copy Protocol (SCP) 237 9.6 World Wide Web (WWW) and HTTP 237 9.6.1