X Port-Based Authentication 73
Summary of Securing the Expanded Network 76
xii
Troubleshooting Switched Networks 76
Troubleshooting Switches 76
Troubleshooting Port Connectivity 77
Hardware Issues 78
Configuration Issues 79
Troubleshooting VLANs and Trunking 80
Native VLAN Mismatches 80
Trunk Mode Mismatches 81
VLANs and IP Subnets 81
Inter-VLAN Connectivity 81
Troubleshooting VTP 82
Unable to See VLAN Details in the show run Command Output 82
Cisco Catalyst Switches Do Not Exchange VTP Information 83
Recently Installed Switch Causes Network Problems 84
All Ports Inactive After Power Cycle 84
Troubleshooting Spanning Tree 85
Use the Diagram of the Network 85
Identify a Bridging Loop 86
Log STP Events 86
Temporarily Disable Unnecessary Features 87
Designate the Root Bridge 87
Verify the Configuration of RSTP 87
Summary of Troubleshooting Switched Networks 87
Chapter Summary 88
Review Questions 88
Chapter 3 Medium-Sized Routed Network Construction 97
Chapter Objectives 97
Reviewing Dynamic Routing 98
Understanding Distance Vector Routing Protocols 103
Route Discovery, Selection, and Maintenance 104
Routing Loops 105
Route Maintenance Using Hold-Down Timers 110
Route Maintenance Using Triggered Updates 111
Route Maintenance Using Hold-Down Timers with Triggered Updates 112
Link-State and Advanced Distance Vector Protocols 115
Link-State Routing Protocol Algorithms 118
Advanced Distance Vector Protocol Algorithm 122
Summary of Reviewing Routing Operations 122
Implementing Variable-Length Subnet Masks 123
Reviewing Subnets 123
Computing Usable Subnetworks and Hosts 123
Introducing VLSMs 125
Route Summarization with VLSM 128
Summary of Implementing Variable-Length Subnet Masks 132
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Chapter Summary 133
Review Questions 133
Chapter 4 Single-Area OSPF Implementation 139
Chapter Objectives 139
Introducing OSPF 139
Establishing OSPF Neighbor Adjacencies 141
SPF Algorithm 143
Configuring and Verifying OSPF 144
Loopback Interfaces 145
Verifying the OSPF Configuration 146
Using OSPF debug Commands 152
Load Balancing with OSPF 154
OSPF Authentication 156
Types of Authentication 156
Configuring Plaintext Password Authentication 157
Example: Plaintext Password Authentication Configuration 158
Verifying Plaintext Password Authentication 159
Summary of OSPF Introduction 159
Troubleshooting OSPF 160
Components of Troubleshooting OSPF 160
Troubleshooting OSPF Neighbor Adjacencies 161
Troubleshooting OSPF Routing Tables 164
Troubleshooting Plaintext Password Authentication 165
Summary of Troubleshooting OSPF 167
Chapter Summary 167
Review Questions 167
Chapter 5 Implementing EIGRP 171
Chapter Objectives 171
Implementing EIGRP 171
Introducing EIGRP 171
Configuring and Verifying EIGRP 174
Load Balancing with EIGRP 181
EIGRP Metric 181
Load Balancing Across Equal Paths 182
Configuring Load Balancing Across Unequal-Cost Paths 182
Example: Variance 183
EIGRP Authentication 184
Creating a Key Chain 185
Configuring MD5 Authentication for EIGRP 188
Example: MD5 Authentication Configuration 188
Verifying MD5 Authentication 190
Summary of Implementing EIGRP 191
xiv
Troubleshooting EIGRP 192
Components of Troubleshooting EIGRP 192
Troubleshooting EIGRP Neighbor Relationships 192
Troubleshooting EIGRP Routing Tables 195
Troubleshooting EIGRP Authentication 198
Example: Successful MD5 Authentication 198
Example: Troubleshooting MD5 Authentication Problems 199
Summary of Troubleshooting EIGRP 200
Chapter Summary 200
Review Questions 201
Chapter 6 Managing Traffic with Access Control Lists 205
Chapter Objectives 205
Access Control List Operation 205
Understanding ACLs 206
ACL Operation 208
Types of ACLs 211
ACL Identification 211
Additional Types of ACLs 214
Dynamic ACLs 214
Reflexive ACLs 216
Time-Based ACLs 217
ACL Wildcard Masking 219
Summary of ACL Operations 221
Configuring ACLs 222
Configuring Numbered Standard IPv4 ACLs 222
Example: Numbered Standard IPv4 ACL??”Permit My Network Only 223
Example: Numbered Standard IPv4 ACL??”Deny a Specific Host 224
Example: Numbered Standard IPv4 ACL??”Deny a Specific Subnet 225
Controlling Access to the Router Using ACLs 227
Configuring Numbered Extended IPv4 ACLs 227
Extended ACL with the established Parameter 229
Numbered Extended IP ACL: Deny FTP from Subnets 231
Numbered Extended ACL: Deny Only Telnet from Subnet 232
Configuring Named ACLs 233
Creating Named Standard IP ACLs 234
Creating Named Extended IP ACLs 235
Named Extended ACL: Deny a Single Host from a Given Subnet 237
Named Extended ACL??”Deny a Telnet from a Subnet 238
Adding Comments to Named or Numbered ACLs 238
Summary of Configuring ACLs 239
Troubleshooting ACLs 239
Problem: Host Connectivity 241
Summary of Troubleshooting ACLs 243
xv
Chapter Summary 244
Review Questions 244
Chapter 7 Managing Address Spaces with NAT and IPv6 249
Chapter Objectives 249
Scaling the Network with NAT and PAT 249
Introducing NAT and PAT 250
Translating Inside Source Addresses 253
Static NAT Address Mapping 256
Dynamic Address Translation 257
Overloading an Inside Global Address 258
Resolving Translation Table Issues 262
Resolving Issues with Using the Correct Translation Entry 264
Summary of Scaling the Network with NAT and PAT 269
Transitioning to IPv6 270
Reasons for Using IPv6 270
Understanding IPv6 Addresses 273
Global Addresses 275
Reserved Addresses 275
Private Addresses 275
Loopback Address 276
Unspecified Address 276
IPv6 over Data Link Layers 277
Assigning IPv6 Addresses 278
Manual Interface ID Assignment 279
EUI-64 Interface ID Assignment 279
Stateless Autoconfiguration 279
DHCPv6 (Stateful) 279
Use of EUI-64 Format in IPv6 Addresses 280
Routing Considerations with IPv6 282
Strategies for Implementing IPv6 283
Configuring IPv6 287
Configuring and Verifying RIPng for IPv6 287
Example: RIPng for IPv6 Configuration 288
Summary of Transitioning to IPv6 289
Chapter Summary 289
Review Questions 290
Chapter 8 Extending the Network into the WAN 297
Chapter Objectives 297
Introducing VPN Solutions 298
VPNs and Their Benefits 298
Types of VPNs 299
xvi
Benefits 302
Restrictions 303
IPsec SSL VPN (WebVPN) 304
Benefits 304
Restrictions 305
Components of VPNs 305
Introducing IPsec 307
IPsec Protocol Framework 313
Summary of Introducing VPN Solutions 314
Establishing a Point-to-Point WAN Connection with PPP 315
Understanding WAN Encapsulations 315
Overview of PPP 317
Configuring and Verifying PPP 320
Example: PPP and CHAP Configuration 322
Example: Verifying PPP Encapsulation Configuration 322
Example: Verifying PPP Authentication 323
Summary of Establishing a Point-to-Point WAN Connection with PPP 324
Establishing a WAN Connection with Frame Relay 325
Understanding Frame Relay 325
Example: Frame Relay Terminology??”DLCI 328
Example: Frame Relay Address Mapping 331
Configuring Frame Relay 334
Example: Configuring Frame Relay Point-to-Point Subinterfaces 336
Example: Configuring Frame Relay Multipoint Subinterfaces 338
Verifying Frame Relay 340
Summary of Establishing a WAN Connection with Frame Relay 347
Troubleshooting Frame Relay WANs 347
Components of Troubleshooting Frame Relay 347
Troubleshooting Frame Relay Connectivity Issues 348
Summary of Troubleshooting Frame Relay WANs 354
Chapter Summary 354
Review Questions 355
Appendix Answers to Chapter Review Questions 361
Index 368
xvii
Icons Used in This Book
Command Syntax Conventions
The conventions used to present command syntax in this book are the same conventions
used in the IOS Command Reference.
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