28.1.2 Type of spanning tree

The Switch supports three types of Spanning Tree Protocols: PVST+, Single Spanning Tree, and Multiple Spanning Tree. Each Spanning Tree Protocol is built differently. The following table provides an overview of the types of Spanning Tree Protocols.

Table 28-1: Spanning Tree types
Name	Build unit	Overview
PVST+	Per-VLAN	This kind of tree is built per VLAN. If multiple VLANs belong to a single port, different tree build results are applied to each VLAN.
Single Spanning Tree	Per switch	This kind of tree is built with all ports on the switch as targets. The tree build results are applied to all ports on the switch regardless of the VLAN configuration.
Multiple Spanning Tree	Per-MST-instance	This kind of Spanning Tree Protocol is built by groups of multiple VLANs, called MST instances. If multiple VLANs belong to a single port, different tree build results are applied to each MST instance.

The Switch allows the above Spanning Tree Protocols to be used as standalone or together. The following table describes which Spanning Tree combinations can be applied.

Table 28-2: Spanning Tree combinations and application ranges
Tree building condition	Applicable topology calculation results
Standalone PVST+	A Spanning Tree Protocol for each VLAN is applied to VLANs for which PVST+ is running. The Spanning Tree Protocol is not applied to other VLANs. PVST+ runs by default on port VLANs for the Switch.
Standalone Single Spanning Tree	Single Spanning Tree is applied to all VLANs. All PVST+ instances are stopped in this configuration.
Combination of PVST+ and Single Spanning Tree	A Spanning Tree Protocol for each VLAN is applied to VLANs for which PVST+ is running. Single Spanning Tree is applied to other VLANs.
Standalone Multiple Spanning Tree	Multiple Spanning Tree is applied to all VLANs.

Note: Multiple Spanning Tree cannot be used in combination with other trees.