what is per vlan spanning tree
STP does not affect ports that connect to workstations or PCs. These ports remain forwarded. Note: The addition or removal of VLANs when STP runs in per-VLAN spanning tree (PVST / PVST+) mode triggers spanning tree recalculation for that VLAN instance and the traffic is disrupted only for that VLAN.The other VLAN parts of a trunk link can forward traffic normally.TP does not affect ports that connect to workstations or PCs. These ports remain forwarded. Note: The addition or removal of VLANs when STP runs in per-VLAN spanning tree (PVST / PVST+) mode triggers spanning tree recalculation for that VLAN instance and the traffic is disrupted only for that VLAN.