27.4.2 Configuring PVST+

Points to note

When the pvst or rapid-pvst operating mode is set, PVST+ automatically runs on port VLANs, but the mode can be changed and PVST+ can be set to start or stop per VLAN. The no spanning-tree vlan command is used to stop operation.

To prevent PVST+ operation for a newly created VLAN, use the no spanning-tree vlan command to set this before the VLAN is created.

Command examples

1. (config)# no spanning-tree vlan 20

   Stops VLAN 20 PVST+ operation.

2. (config)# spanning-tree vlan 20

   Runs the stopped VLAN 20 PVST+.

Notes

• PVST+ runs automatically when nothing is displayed for the configuration. The no spanning-tree vlan command can be used to stop it, and the configuration can be checked to make sure it has stopped.

• The maximum number of port VLANs on which PVST+ can run is 250. It will not run automatically on any subsequently created port VLANs.