PVST

Per VLAN Spanning Tree (PVST) is a protocol running a separate instance of the 802.1Q STP standard protocol per each VLAN configured on the device. RSTP standard protocol per each VLAN configured on the device. The PVST protocol is a protocol that was designed to address the problem that exist with STP/ RSTP standard based implementation - that in some cases a port that is in blocking mode (for more than 1 VLANs) may create an efficient usage of bandwidth since it cannot be used for any traffic forwarding.

PVST addresses this issue by assigning a separate spanning tree instance for each VLAN configured on the device. Up to 126 PVST instances are supported. this means that if more than 126 VLANs are configured on the device, PVST cannot be enabled. Likewise, if PVST is enabled you cannot configure more than 126 VLANs

The device supports the PVST/RPVST Plus flavor of the protocols. This section refers to PVST to describe both PVST+ and RPVST+ feature behavior.