26.2.2 To set the enforcement mode

The operating mode of a switch can be set so that various Spanning Tree Protocols can be used. The table below describes the switch operating modes. If no operating mode is set, operation is performed in pvst mode.

Keep in mind that when rapid-pvst is specified for the operating mode, the Single Spanning Tree default is STP.

Table 26-9: Spanning Tree operation modes
Command name	Description
spanning-tree disable	Disables a Spanning Tree Protocol.
spanning-tree mode pvst	Allows Single Spanning Tree to be used with PVST+. PVST+ is used for operation by default. Single Spanning Tree does not run by default.
spanning-tree mode rapid-pvst	Allows Single Spanning Tree to be used with PVST+. Rapid PVST+ for a rapid Spanning Tree Protocol runs by default. Single Spanning Tree does not run by default.
spanning-tree mode mst	Runs Multiple Spanning Tree.

<Structure of this section>

(1) Operating-mode pvst setting

Points to note

The example below shows how to set the switch operating mode to pvst. When a port VLAN is created, PVST+ is automatically run on the VLAN. Each VLAN can be changed to Rapid PVST+.

Single Spanning Tree does not run by default, but can run through settings. Operation uses STP by default, but can be changed to Rapid STP.

Command examples

(config)# spanning-tree mode pvst

Sets the Spanning Tree operating mode to pvst. PVST+ is automatically run for port VLANs.
(config)# spanning-tree vlan 10 mode rapid-pvst

Changes the operating mode of VLAN 10 to Rapid PVST+. Other port VLANs are run using PVST+, and VLAN 10 runs using Rapid PVST+.
(config)# spanning-tree single

Runs Single Spanning Tree. This is applied to VLANs for which PVST+ is not used. By default, STP is used for operation.
(config)# spanning-tree single mode rapid-stp

Changes Single Spanning Tree to Rapid STP.

(2) Operating-mode rapid-pvst setting

Points to note

The example below shows how to set the switch operating mode to rapid-pvst. When a port VLAN is created, Rapid PVST+ is automatically run on the VLAN. Each VLAN can be changed to PVST+.

Single Spanning Tree does not run by default, but can run through settings. Keep in mind that when rapid-pvst is specified for the operating mode, the Single Spanning Tree default is STP.

Command examples

(config)# spanning-tree mode rapid-pvst

Sets the Spanning Tree operating mode to rapid-pvst. Rapid PVST+ is automatically run for port VLANs.
(config)# spanning-tree vlan 10 mode pvst

Changes the operating mode of VLAN 10 to PVST+. Other port VLANs are run using Rapid PVST+, and VLAN 10 runs using PVST+.
(config)# spanning-tree single

Runs Single Spanning Tree. This is applied to VLANs for which PVST+ is not used. By default, STP is used for operation.
(config)# spanning-tree single mode rapid-stp

Changes Single Spanning Tree to Rapid STP.

(3) Operating-mode mst setting

Points to note: When Multiple Spanning Tree is used, set the switch operating mode to mst. Multiple Spanning Tree is applied to all VLANs. When Multiple Spanning Tree is used, PVST+ and Single Spanning Tree cannot be used together.

Command examples

(config)# spanning-tree mode mst

Runs Multiple Spanning Tree.

(4) Setting to stop spanning tree

Points to note: If Spanning Tree Protocols are not used, disable can be set to stop all Spanning Tree Protocols on the Switch.

Command examples

(config)# spanning-tree disable

Stops all Spanning Tree operation.