LAN Switching and Wireless -

CCNA Exploration Companion Guide

Wayne Lewis, Ph.D.

Cisco Press 800 East 96th Street

Indianapolis, Indiana 46240 USA

x LAN Switching and Wireless, CCNA Exploration Companion Guide

Contents

Introduction xx

Chapter 1 LAN Design 1

Objectives 1

Key Terms 1

Switched LAN Architecture 2 The Hierarchical Network Model 2

Access Layer 2 Distribution Layer 3 Core Layer 3 A Hierarchical Network in a Medium-Sized Business 4 Benefits of a Hierarchical Network 4

Principles of Hierarchical Network Design 6 Network Diameter 7 Bandwidth Aggregation 8 Redundancy 9

What Is a Converged Network? 10 Legacy Equipment 10 Advanced Technology 11 New Options 12 Separate Voice, Video, and Data Networks 13

Matching Switches to Specific LAN Functions 15 Considerations for Hierarchical Network Switches 15

Traffic Flow Analysis 15 User Community Analysis 17 Data Stores and Data Servers Analysis 19 Topology Diagrams 20

Switch Features 22 Switch Form Factors 22 Switch Performance 24 Power over Ethernet and Layer 3 Functionality 26

Switch Features in a Hierarchical Network 28 Access Layer Switch Features 28 Distribution Layer Switch Features 30 Core Layer Switch Features 31

Switches for Small and Medium Sized Business (SMB) 33 Catalyst Express 500 33 Catalyst 2960 34 Catalyst 3560 35 Catalyst 3750 36

XI

Catalyst 4500 36 Catalyst 4900 37 Catalyst 6500 38 Comparing Switches 39

Summary 40

Labs 40

Check Your Understanding 41

Challenge Questions and Activities 44

Chapter 2 Basic Swi tch Concepts and Conf igurat ion 45

Objectives 45

Key Terms 45

Introduction to Ethernet/802.3 LANs 46

Key Elements of Ethernet/802.3 Networks 46 CSMA/CD 46 Ethernet Communications 47 Duplex Settings 49 Switch Port Settings 50 Switch MAC Address Table 51

Design Considerations for Ethernet/802.3 Networks 52 Bandwidth and Throughput 52 Collision Domains 53 Broadcast Domains 54 Network Latency 54 Network Congestion 55 LAN Segmentation 55

LAN Design Considerations 56

Forwarding Frames Using a Switch 58

Switch Forwarding Methods 59

Symmetric and Asymmetric Switching 60

Memory Buffering 60

Layer 2 and Layer 3 Switching 62

Switch Management Configuration 63

Navigating Command-Line Interface Modes 63

GUI-Based Alternatives to the CLl 65

Using the Help Facility 68

Accessing the Command History 70

Switch Boot Sequence 71

Prepare to Configure the Switch 72

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Basic Switch Configuration 72 Management Interface 73 Default Gateway 74 Duplex and Speed 75 HTTP Access 76 MAC Address Table Management 77

Verifying Switch Configuration 78 Basic Switch Management 80

Backing Up and Restoring Switch Configuration Files 80 Using a TFTP Server with Switch Configuration Files 82 Clearing Switch Configuration Information 84

Configuring Switch Security 85 Configuring Password Options 85

Securing Console Access 85 Securing Virtual Terminal Access 87 Securing Privileged EXEC Access 88 Encrypting Switch Passwords 89 Password Recovery 90

Login Banners 92 Configure Telnet and SSH 93

Configuring Telnet 93 Configuring SSH 94

Common Security Attacks 96 MAC Address Flooding 96 Spoofing Attacks 100 С DP Attacks 101 Telnet Attacks 102

Security Tools 103 Configuring Port Security 105 Securing Unused Ports 110

Summary 111 Labs 111 Check Your Understanding 112

Challenge Questions and Activities 117

Chapter 3 VLANs 121 Objectives 121

Key Terms 121

Introducing VLANs 122 Defining VLANs 122 Benefits of VLANs 124

XIII

VLAN ID Ranges 126

Types of VLANs 126

Voice VLANs 131

Network Application Traffic Types 133

Switch Port Membership Modes 136

Controlling Broadcast Domains with VLANs 138

VLANTrunking 143

VLAN Trunks 144 IEEE 802.1Q Frame Tagging 145 Native VLANs 147

Trunking Operation 148

Trunking Modes 149

Configure VLANs and Trunks 151

Configure a VLAN 152

Managing VLANs 155

Managing VLAN Memberships 158

Configure a Trunk 160

Troubleshooting VLANs and Trunks 164

Common Problems with Trunks 165

A Common Problem with VLAN Configurations 171

Summary 173

Labs 173

Check Your Understanding 174

Challenge Questions and Activities 178

Chapter 4 VTP 181

Objectives 181

Key Terms 181

VTP Concepts 182

What Is VTP? 182 Benefits of VTP 184 VTP Components 184

VTP Operation 186

Default VTP Configuration 186

VTP Domains 188

VTP Advertising 190 VTP Configuration Revision Number 192 VTP Advertisement Types 193

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VTP Modes 197 VTP Server-to-Client Behavior 198 VTP Server-to-Transparent-to-Client Behavior 199

VTP Pruning 201 VTP Pruning in Action 202

Configure VTP 204

Configuring VTP 204 Steps to Configuring VTP 206

Troubleshooting VTP Configurations 212 Incompatible VTP Versions 212 VTP Password Issues 212 Incorrect VTP Domain Name 213 All Switches Set to VTP Client Mode 214 VTP Troubleshooting Example 215

Managing VLANs on a VTP Server 217

Summary 219

Labs 219

Check Your Understanding 220

Challenge Questions and Activities 224

Chapter 5 STP 227

Objectives 227

Key Terms 227

Redundant Layer 2 Topologies 229

Redundancy 229

Issues with Redundancy 234 Broadcast Storms 238 Duplicate Unicast Frames 240

Real-World Redundancy Issues 241 Loops in the Wiring Closet 242 Loops in Cubicles 243

Introduction to STP 244

Spanning-Tree Algorithm (STA) 244 STP Topology 245 Port Types in the Spanning-Tree Algorithm 247 Root Bridge 248 Best Paths 249

STP BPDU 252 BPDU Process 253

Bridge ID 258 Configure and Verify the BID 261

Port Roles 263 Configure Port Priority 265 Port Role Decisions 266

STP Port States and BPDU Timers 268 Cisco PortFast 271

STP Convergence 273

Step 1. Elect a Root Bridge 273 Verify Root Bridge Election 274

Step 2. Elect Root Ports 276 Verify Root Port Election 278

Step 3. Elect Designated and Nondesignated Ports 279

Verify Designated and Nondesignated Port Election 283 STP Topology Change 285

PVST+, RSTP, and Rapid PVST+ 286

Cisco and IEEE STP Variants 287 Per-VLAN Spanning-Tree (PVST) Overview 287 Per-VLAN Spanning-Tree Plus (PVST+) Overview 287 Rapid Spanning-Tree Protocol (RSTP) Overview 288 Multiple Spanning-Tree Protocol (MSTP) Overview 288

PVST+ 288 Configure PVST+ 291

RSTP 294 RSTP BPDU 295

Edge Ports 296

Link Types 297

RSTP Port States and Port Roles 298 RSTP Proposal and Agreement Process 301

Configuring Rapid PVST+ 309

Design STP for Trouble Avoidance 312 Minimize the Number of Blocked Ports 313 Use Layer 3 Switching 314 Keep STP Even if It Is Unnecessary 316 Keep Traffic off of the Management VLAN 316

Troubleshoot STP Operation 316 PortFast Configuration Error 317 Network Diameter Issues 318

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Summary 320

Labs 320

Check Your Understanding 321

Challenge Questions and Activities 327

Chapter 6 Inter-VLAN Routing 331

Objectives 331

Key Terms 331

Inter-VLAN Routing 332 Introducing Inter-VLAN Routing 332

One-Router-lnterface-per-VLAN 332 Router-on-a-Stick 334 Layer 3 Switch 336

Interfaces and Subinterfaces 337 One-Router-lnterface-per-VLAN 338 Router-on-a-Stick 341 Considerations for Inter- VLAN Routing Methods 345

Configuring Inter-VLAN Routing 347

Configure Inter-VLAN Routing 347

Configure Router-on-a-Stick Inter-VLAN Routing 351

Troubleshooting Inter-VLAN Routing 356

Switch Configuration Issues 356 Switch Cisco IOS Commands for Troubleshooting 359

Router Configuration Issues 360 Router Cisco IOS Commands for Troubleshooting 361

IP Addressing Issues 362

IP Addressing Cisco IOS Verification Commands 364

Summary 366

Labs 366

Check Your Understanding 367

Challenge Questions and Activities 373

Chapter 7 Basic Wireless Concepts and Configuration 377

Objectives 377

Key Terms 377

The Wireless LAN 379 Why Use Wireless? 379

Wireless LANs 380 Comparing a WLAN to a LAN 381 Wireless LAN Components 383

XVII

Wireless LAN Standards 383 Wi-Fi Certification 386

Wireless Infrastructure Components 387 Wireless NICs 387 Wireless Access Points 388 Wireless Routers 390

Wireless Operation 391 Configurable Wireless Parameters 391 Wireless Topologies 393 Wireless Association 396

Planning the Wireless LAN 399

Wireless LAN Security 402

Threats to Wireless Security 402 Rogue Access Points 402 Man-in-the-Middle Attacks 403 Denial of Service 404

Wireless Security Protocols 405 Authenticating the Wireless LAN 407 Wireless Encryption 408 Controlling Access to the WLAN 409

Configure Wireless LAN Access 410

Configuring the Wireless Access Point 410 Configuring Basic Wireless Settings 413 Configuring Wireless Security 415

Configuring a Wireless NIC 418 Scan for SSlDs 418 Select the Wireless Security Protocol 420 Verify Connectivity to the WLAN 423

Troubleshooting Simple WLAN Problems 424

A Systematic Approach to WLAN Troubleshooting 424

Solve Access Point Radio and Firmware Issues 426

Channel Settings 426

RF Interference 429

Access Point Placement 431

Authentication and Encryption 434

Summary 436

Labs 436

Check Your Understanding 437

Challenge Questions and Activities 441

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Appendix Check Your Understanding and Challenge Questions

Answer Key 445

Glossary 461

Index 475