Introduction xxxiv Your Study Plan 2 Part I Introduction to Networking 15 Chapter 1 Introduction to TCP/IP Networking 16 "Do I Know This Already?" Quiz 17 Foundation Topics 18 Perspectives on Networking 18 TCP/IP Networking Model 19 History Leading to TCP/IP 20 Overview of the TCP/IP Networking Model 21 TCP/IP Application Layer 23 HTTP Overview 23 HTTP Protocol Mechanisms 23 TCP/IP Transport Layer 24 TCP Error Recovery Basics 25 Same-Layer and Adjacent-Layer Interactions 25 TCP/IP Network Layer 26 Internet Protocol and the Postal Service 26 Internet Protocol Addressing Basics 27 IP Routing Basics 28 TCP/IP Data-Link and Physical Layers 29 Data Encapsulation Terminology 31 Names of TCP/IP Messages 31 OSI Networking Model and Terminology 32 Comparing OSI and TCP/IP Layer Names and Numbers 33 Chapter Review 34 Chapter 2 Fundamentals of Ethernet LANs 36 "Do I Know This Already?" Quiz 36 Foundation Topics 38 An Overview of LANs 38 Typical SOHO LANs 39 Typical Enterprise LANs 40 The Variety of Ethernet Physical Layer Standards 41 Consistent Behavior over All Links Using the Ethernet Data-Link Layer 42 Building Physical Ethernet LANs with UTP 43 Transmitting Data Using Twisted Pairs 43 Breaking Down a UTP Ethernet Link 44 UTP Cabling Pinouts for 10BASE-T and 100BASE-T 46 Straight-Through Cable Pinout 46 Choosing the Right Cable Pinouts 48 Automatic Rewiring with Auto-MDIX 49 UTP Cabling Pinouts for 1000BASE-T 49 Building Physical Ethernet LANs with Fiber 50 Fiber Cabling Transmission Concepts 50 Using Fiber with Ethernet 52 Sending Data in Ethernet Networks 53 Ethernet Data-Link Protocols 53 Ethernet Addressing 54 Identifying Network Layer Protocols with the Ethernet Type Field 56 Error Detection with FCS 56 Sending Ethernet Frames with Switches and Hubs 57 Sending in Modern Ethernet LANs Using Full Duplex 57 Using Half Duplex with LAN Hubs 58 Chapter Review 60 Chapter 3 Fundamentals of WANs and IP Routing 62 "Do I Know This Already?" Quiz 62 Foundation Topics 64 Wide-Area Networks 64 Leased-Line WANs 64 Physical Details of Leased Lines 65 Data-Link Details of Leased Lines 66 How Routers Use a WAN Data Link 67 Ethernet as a WAN Technology 69 Ethernet WANs That Create a Layer 2 Service 70 How Routers Route IP Packets Using Ethernet WAN Links 70 IP Routing 71 Network Layer Routing (Forwarding) Logic 72 Host Forwarding Logic: Send the Packet to the Default Router 73 R1 and R2''s Logic: Routing Data Across the Network 73 R3''s Logic: Delivering Data to the End Destination 73 How Network Layer Routing Uses LANs and WANs 73 How IP Addressing Helps IP Routing 76 Rules for Groups of IP Addresses (Networks and Subnets) 76 The IP Header 77 How IP Routing Protocols Help IP Routing 77 Other Network Layer Features 79 Using Names and the Domain Name System 79 The Address Resolution Protocol 80 ICMP Echo and the ping Command 81 Chapter Review 82 Part I Review 84 Part II Implementing Ethernet LANs 87 Chapter 4 Using the Command-Line Interface 88 "Do I Know This Already?" Quiz 88 Foundation Topics 90 Accessing the Cisco Catalyst Switch CLI 90 Cisco Catalyst Switches 90 Accessing the Cisco IOS XE CLI 91 The Operating System in Cisco Catalyst Switches 92 Accessing the IOS XE CLI 92 Cabling the Console Connection 93 Configuring a Terminal Emulator 95 Accessing the CLI with Telnet and SSH 96 User and Enable (Privileged) Modes 96 Password Security for CLI Access from the Console 98 Accessing the CLI with the WebUI 99 CLI Help Features 101 The debug and show Commands 103 Configuring Cisco IOS Software 103 Configuration Submodes and Contexts 104 Storing Switch Configuration Files 106 Copying and Erasing Configuration Files 109 Chapter Review 109 Chapter 5 Analyzing Ethernet LAN Switching 112 "Do I Know This Already?" Quiz 112 Foundation Topics 114 LAN Switching Concepts 114 Overview of Switching Logic 115 Forwarding Known Unicast Frames 116 Learning MAC Addresses 118 Flooding Unknown Unicast and Broadcast Frames 119 Avoiding Loops Using Spanning Tree Protocol 120 LAN Switching Summary 121 Verifying and Analyzing Ethernet Switching 121 Demonstrating MAC Learning 122 Switch Interfaces 123 Finding Entries in the MAC Address Table 124 Managing the MAC Address Table (Aging, Clearing) 126 MAC Address Tables with Multiple Switches 127 Chapter Review 128 Chapter 6 Configuring Basic Switch Management 132 "Do I Know This Already?" Quiz 132 Foundation Topics 134 Securing the Switch CLI 134 Securing User Mode and Privileged Mode with Simple Passwords 135 Securing User Mode Access with Local Usernames and Passwords 139 Securing User Mode Access with External Authentication Servers 141 Securing Remote Access with Secure Shell 142 Enabling and Securing the WebUI 145 Enabling IPv4 for Remote Access 146 Host and Switch IP Settings 147 Configuring IPv4 on a Switch 149 Configuring a Switch to Learn Its IP Address with DHCP 150 Verifying IPv4 on a Switch 150 Miscellaneous Settings Useful in the Lab 151 History Buffer Commands 151 The logging synchronous, exec-timeout, and no ip domain-lookup Commands 152 Chapter Review 153 Chapter 7 Configuring and Verifying Switch Interfaces 158 "Do I Know This Already?" Quiz 158 Foundation Topics 161 Configuring Switch Interface Speed and Duplex 161 IEEE Autonegotiation Concepts 161 Autonegotiation Under Working Conditions 161 Autonegotiation Results When Only One Node Uses Autonegotiation 163 Autonegotiation and LAN Hubs 165 Configuring Autonegotiation, Speed, and Duplex 165 Using Autonegotiation on Cisco Switches 165 Setting Speed and Duplex Manually 169 Using Auto-MDIX on Cisco Switches 170 Managing Switch Interface Configuration 172 The Description and Interface Range Commands 172 Administratively Controlling Interface State with shutdown 173 Removing Configuration with the no Command 174 Analyzing Switch Interface Status and Statistics 176 Interface Status Codes 176 The Duplex Mismatch Issue 177 Common Layer 1 Problems on Working Interfaces 178 Chapter Review 180 Part II Review 184 Part III Implementing VLANs and STP 187 Chapter 8 Implementing Ethernet Virtual LANs 188 "Do I Know This Already?" Quiz 189 Foundation Topics 191 Virtual LAN Concepts 191 Creating Multiswitch VLANs Using Trunking 192 VLAN Tagging Concepts 193 The 802.1Q and ISL VLAN Trunking Protocols 194 Forwarding Data Between VLANs 195 The Need for Routing Between VLANs 195 Routing Packets Between VLANs with a Router 196 VLAN and VLAN Trunking Configuration and Verification 197 Creating VLANs and Assigning Access VLANs to an Interface 197 VLAN Configuration Example 1: Full VLAN Configuration 198 VLAN Configuration Example 2: Shorter VLAN Configuration 201 VLAN Trunking Protocol 201 VLAN Trunking Configuration 203 Implementing Interfaces Connected to Phones 207 Data and Voice VLAN Concepts 208 Data and Voice VLAN Configuration and Verification 209 Summary: IP Telephony Ports on Switches 212 Troubleshooting VLANs and VLAN Trunks 212 Confirm the Correct Access VLAN Is Assigned 213 Access VLANs Undefined or Disabled 213 Mismatched Trunking Operational States 215 The Supported VLAN List on Trunks 217 Mismatched Native VLAN on a Trunk 218 Chapter Review 218 Chapter 9 Spanning Tree Protocol Concepts 222 "Do I Know This Already?" Quiz 223 Foundation Topics 224 STP and RSTP Basics 224 The Need for Spanning Tree 225 What Spanning Tree Does 227 How Spanning Tree Works 228 The STP Bridge ID and Hello BPDU 229 Electing the Root Switch 230 Choosing Each Switch''s Root Port 232 Choosing the Designated Port on Each LAN Segment 234 Configuring to Influence the STP Topology 235 Details Specific to STP (and Not RSTP) 236 STP Activity When the Network Remains Stable 236 STP Timers That Manage STP Convergence 237 Changing Interface States with STP 238 Rapid STP Concepts 239 Comparing STP and RSTP 240 RSTP and the Alternate (Root) Port Role 241 RSTP States and Processes 243 RSTP and the Backup (Designated) Port Role 244 RSTP Port Types 245 Optional STP Features 246 EtherChannel 246 PortFast 247 BPDU Guard 248 BPDU Filter 248 BPDU Filter to Prevent Loops on PortFast Ports 249 BPDU Filter to Disable STP on a Port 249 Root Guard 250 Loop Guard 251 Chapter Review 254 Chapter 10 RSTP and EtherChannel Configuration 256 "Do I Know This Already?" Quiz 256 Foundation Topics 259 Understanding RSTP Through Configuration 259 The Need for Multiple Spanning Trees 260 STP Modes and Standards 260 The Bridge ID and System ID Extension 261 Identifying Switch Priority and the Root Switch 263 Switch Priority and Identifying the Root Switch 263 Switch Priority Using Root Primary and Secondary 265 RSTP (One Tree) and RPVST+ (One Tree P.