Enabling and configuring PVST+ globally

Use this procedure to enable and set parameters for PVST+.

About this task

You can enable PVST+ with one or more parameters configured. The parameters can be configured or changed individually by entering the commands in steps 1 and 2, running the parameter command, verifying the result, and then saving the configuration.

For more information about spanning trees and spanning tree parameters, see the introductory sections in the Spanning Tree Protocol chapter.

Procedure

Enter global configuration mode.
```
device# configure terminal
```

Enable PVST+.

device(config)# protocol spanning-tree pvst

Configure the bridge priority for the common instance.
```
device(config-pvst)# bridge-priority 4096
```
Valid values range from 0 through 61440 in increments of 4096. Assigning a lower priority value indicates that the bridge might become root.
You can shut down PVST+ by entering the shutdown command when in PVST configuration mode.
Configure the forward delay parameter.
```
device(config-pvst)# forward-delay  11
```
Configure the hello time parameter.
```
device(config-pvst)# hello-time 2
```
Configure the maximum age parameter.
```
device(config-pvst)# max-age 7
```
Return to privileged exec mode.
```
device(config-pvst)# end
```

Verify the configuration.

device#  show spanning-tree brief
VLAN 1

 Spanning-tree Mode: PVST Protocol

      Root ID      Priority 4097
                   Address 01e0.5200.0180
                   Hello Time 2, Max Age 7, Forward Delay 11

      Bridge ID    Priority 4097
                   Address 01e0.5200.0180
                   Hello Time 2, Max Age 7, Forward Delay 11

 Interface     Role  Sts  Cost       Prio  Link-type        Edge
 ---------------------------------------------------------------------

VLAN 100

 Spanning-tree Mode: PVST Protocol

      Root ID      Priority 4196
                   Address 01e0.5200.0180
                   Hello Time 2, Max Age 7, Forward Delay 11

      Bridge ID    Priority 4196
                   Address 01e0.5200.0180
                   Hello Time 2, Max Age 7, Forward Delay 11

 Interface     Role  Sts  Cost       Prio  Link-type        Edge
 ---------------------------------------------------------------------

Observe that the settings comply with the formula set out in the STP parameters section, as:

(2 × (forward delay - 1)) ≥ maximum age ≥ (2 × (hello time + 1))

or in this case: 20 ≥7 ≥ 6.

Save the configuration.

device# copy running-config startup-config

PVST+ configuration example

device# configure terminal
device(config)# protocol spanning-tree pvst
device(config-pvst)# bridge-priority 4096
device(config-pvst)# forward-delay 11
device(config-pvst)# hello-time 2
device(config-pvst)# max-age 7
device(config-pvst)# end
device# show spanning-tree brief
device# copy running-config startup-config

What to do next

For more information about configuring PVST+ parameters, see STP parameters. PVST+, R-PVST+, and other types of spanning trees share many tasks with STP.