Changing the Spanning-Tree Mode The switch supports three spanning-tree modes: per-VLAN spanning tree plus (PVST+), Rapid PVST+, or Multiple Spanning Tree Protocol (MSTP). By default, the device runs the Rapid PVST+ protocol. If you want to enable a mode that is different from the default mode, this procedure is required. Procedure Configuring Spanning Tree Protocol Changing the Spanning-Tree Mode Command or Action Purpose Step 1 enable Example: Device> enable Enables privileged EXEC mode. Enter your password if prompted. Step 2 configure terminal Example: Device# configure terminal Enters global configuration mode. Step 3 spanning-tree mode {pvst | mst | rapid-pvst} Example:
Device(config)# spanning-tree mode pvst Configures a spanning-tree mode. All stack members run the same version of spanning tree. • Select pvst to enable PVST+. • Select mst to enable MSTP. • Select rapid-pvst to enable rapid PVST+. Step 4 interface interface-id Example: Device(config)# interface GigabitEthernet1/0/1 Specifies an interface to configure, and enters interface configuration mode. Valid interfaces include physical ports, VLANs, and port channels. The VLAN ID range is 1 to 4094. The port-channel range is 1 to 48. Step 5 spanning-tree link-type point-to-point Example:
Device(config-if)# spanning-tree link-type point-to-point Specifies that the link type for this port is point-to-point. If you connect this port (local port) to a remote port through a point-to-point link and the local port becomes a designated port, the device negotiates with the remote port and rapidly changes the local port to the forwarding state. Step 6 end Example: Device(config-if)# end Returns to privileged EXEC mode. Step 7 clear spanning-tree detected-protocols Example: If any port on the device is connected to a port on a legacy IEEE 802.1D device, this command Configuring Spanning Tree Protocol 12