lan switching and wireless - gbv
TRANSCRIPT
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
xii LAN Switching and Wireless, CCNA Exploration Companion Guide
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
xiv LAN Switching and Wireless, CCNA Exploration Connpanion Guide
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
xvi LAN Switching and Wireless, CCNA Exploration Companion Guide
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
xviii LAN Switching and Wireless, CCNA Exploration Companion Guide
Appendix Check Your Understanding and Challenge Questions
Answer Key 445
Glossary 461
Index 475