Enabling PVST+ Support Manually
To immediately enable PVST+ support on a port,
enter the pvst-mode command in interface configuration mode
device(config)# interface ethernet 1/1/1 device(config-if-1/1/1)# pvst-mode
Note: If you disable PVST+ support, by entering the
no pvst-mode command in interface configuration mode, the
software still automatically enables PVST+ support if the port receives a BPDU
with
PVST+ format. Note: If IEEE 802.1w and PVST+ (either by
auto-detection or by explicit configuration) are enabled on a tagged VLAN port,
IEEE
802.1w will treat the PVST BPDUs as legacy IEEE 802.1D BPDUs.