MSTP based on the basic STP/RSTP function divides a switching network into multiple regions, each of which has multiple spanning trees that are independent of each other. MSTP isolates different VLANs' traffic, and load-balances VLAN traffic. MSTP is configured on switches to trim a ring network to a loop-free network. Devices start spanning tree calculation after the working mode is set and MSTP is enabled. To intervene in the spanning tree calculation, use any of the following methods:
Manually configure the root bridge and secondary root bridge.
Set a priority for a switch in an MSTI. The lower the numerical value, the higher the priority of the switch and the more likely the switch becomes a root bridge.
Set a path cost for a port in an MSTI. The lower the numerical value, the smaller the cost of the path from the port to the root bridge and the more likely the port becomes a root port (assuming the same calculation method is used).
Set a priority for a port in an MSTI. The lower the numerical value, the more likely the port becomes a designated port.