Enabling and configuring PVST+ globally

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

1. Enter global configuration mode.
   

   device# configure terminal
   

2. Enable PVST+.
   

   device(config)# protocol spanning-tree pvst
   

3. 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.

4. Configure the forward delay parameter.
   

   device(config-pvst)# forward-delay  11
   

5. Configure the hello time parameter.
   

   device(config-pvst)# hello-time 2
   

6. Configure the maximum age parameter.
   

   device(config-pvst)# max-age 7
   

7. Return to privileged exec mode.
   

   device(config-pvst)# end
   

8. 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.

9. 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