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Chapter 9 
Spanning Tree Protocol Concepts 210
“Do I Know This Already?” Quiz 210
Foundation Topics 212
STP and RSTP Basics 212
The Need for Spanning Tree 213
What Spanning Tree Does 215
How Spanning Tree Works 216
The STP Bridge ID and Hello BPDU 218
Electing the Root Switch 218
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Choosing Each Switch’s Root Port 220
Choosing the Designated Port on Each LAN Segment 222
Configuring to Influence the STP Topology 223
Details Specific to STP (and Not RSTP) 224
STP Activity When the Network Remains Stable 224
STP Timers That Manage STP Convergence 225
Changing Interface States with STP 227
Rapid STP Concepts 228
Comparing STP and RSTP 229
RSTP and the Alternate (Root) Port Role 230
RSTP States and Processes 232
RSTP and the Backup (Designated) Port Role 233
RSTP Port Types 233
Optional STP Features 234
EtherChannel 234
PortFast 235
BPDU Guard 236
Chapter Review 236
Chapter 10 RSTP and EtherChannel Configuration 238
“Do I Know This Already?” Quiz 238
Foundation Topics 240
Understanding RSTP Through Configuration 240
The Need for Multiple Spanning Trees 241
STP Modes and Standards 242
The Bridge ID and System ID Extension 243
How Switches Use the Priority and System ID Extension 245
RSTP Methods to Support Multiple Spanning Trees 246
Other RSTP Configuration Options 247
Configuring Layer 2 EtherChannel 247
Configuring a Manual Layer 2 EtherChannel 248
Configuring Dynamic EtherChannels 250
Physical Interface Configuration and EtherChannels 251
EtherChannel Load Distribution 253
Configuration Options for EtherChannel Load Distribution 254
The Effects of the EtherChannel Load Distribution Algorithm 255
Chapter Review 257
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