Wendell Odom, CCIE Enterprise No. 1624, was the first Cisco Press author for Cisco certification guides. He wrote all prior editions of this book, along with books on topics ranging from introductory networking to CCENT, CCNA R&S, CCNA DC, CCNP ROUTE, CCNP QoS, and CCIE R&S. In his four decades as a networker, he has worked as a network engineer, consultant, systems engineer, instructor, and course developer. He now spends his time focused on updating the CCNA books, his blog ([...] building his new CCNA YouTube channel ([...] and teaching online ([...] You can find him at [...] Twitter (@WendellOdom), and at his blog, which provides a variety of free CCNA learning resources.

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 R2s Logic: Routing Data Across the Network 73
R3s 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 Switchs 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 Per VLAN) 266
Identifying Port Cost, Role, and State 266
Identifying Optional STP Features 269
PortFast and BPDU Guard 269
PortFast and BPDU Guard on an Access Port with One Endpoint 269
PortFast on VLAN Trunks and Voice Pseudo-Trunks 271
Global Configuration of PortFast and BPDU Guard...