Configure the Spanning Tree Mode
Specifies the Multiple Spanning Tree Protocol (MSTP) or Rapid Spanning Tree Protocol (RSTP) mode. If you do not specify a protocol, the switch uses the default mode, which is mstp. If you change the spanning tree mode, you must save the current configuration and restart the switch.
Procedure
Example
Configure the STP mode:
Switch:1(config)#
boot
config flags spanning-tree-mode mstp
Warning: Please save the configuration and reboot the switch for this to take effect. Warning: Please carefully save your configuration files before starting configuring the switch in RSTP or MSTP mode.