Cisco Nexus 5000 Series Switch CLI Software Configuration Guide (OL-16597-01, July 2009)

Information About Rapid PVST+ 149
Understanding STP 150
STP Overview 150
Understanding How a Topology is Created 150
Understanding the Bridge ID 150
Bridge Priority Value 151
Extended System ID 151
STP MAC Address Allocation 151
Understanding BPDUs 152
Election of the Root Bridge 153
Creating the Spanning Tree Topology 153
Understanding Rapid PVST+ 154
Rapid PVST+ Overview 154
Rapid PVST+ BPDUs 156
Proposal and Agreement Handshake 157
Protocol Timers 158
Port Roles 158
Port States 159
Rapid PVST+ Port State Overview 159
Blocking State 160
Learning State 160
Forwarding State 160
Disabled State 161
Summary of Port States 161
Synchronization of Port Roles 161
Processing Superior BPDU Information 162
Processing Inferior BPDU Information 162
Detecting Unidirectional Link Failure 163
Port Cost 163
Port Priority 164
Rapid PVST+ and IEEE 802.1Q Trunks 164
Rapid PVST+ Interoperation with Legacy 802.1D STP 164
Rapid PVST+ Interoperation with 802.1s MST 165
Configuring Rapid PVST+ 165
Enabling Rapid PVST+ 165
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01 xi
Contents