Enabling PVST+ support manually
To immediately enable PVST+ support on a port, enter commands such as the following.
device(config)# interface ethernet 1/1/1 device(config-if-1/1/1)# pvst-mode
NOTE
If you disable PVST+ support, the software still automatically enables PVST+ support if the port receives a BPDU with PVST+ format.
NOTE
If 802.1W and pvst-mode (either by auto-detection or by explicit configuration) are enabled on a tagged VLAN port, 802.1W will treat the PVST BPDUs as legacy 802.1D BPDUs.