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Multiple Spanning Tree Protocol (MSTP)
Multiple spanning tree protocol (MSTP) specified in IEEE 802.1Q-2003 is a rapid spanning tree protocol (RSTP)-based
spanning tree variation that improves on per-VLAN spanning tree plus (PVST+).
Protocol Overview
MSTP allows multiple spanning tree instances and allows you to map many VLANs to one spanning tree instance to reduce the
total number of required instances.
In contrast, PVST+ allows a spanning tree instance for each VLAN. This 1:1 approach is not suitable if you have many VLANs,
because each spanning tree instance costs bandwidth and processing resources.
In the following illustration, three VLANs are mapped to two multiple spanning tree instances (MSTI). VLAN 100 traffic takes a
different path than VLAN 200 and 300 traffic. The behavior demonstrates how you can use MSTP to achieve load balancing.
Figure 85. MSTP with Three VLANs Mapped to TWO Spanning Tree Instances
Topics:
Spanning Tree Variations
Implementation Information
Configure Multiple Spanning Tree Protocol
Enable Multiple Spanning Tree Globally
Creating Multiple Spanning Tree Instances
Influencing MSTP Root Selection
Interoperate with Non-Dell Networking OS Bridges
Changing the Region Name or Revision
Modifying Global Parameters
Enable BPDU Filtering Globally
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490 Multiple Spanning Tree Protocol (MSTP)