MSTP Properties

The global MSTP configures a separate Spanning Tree for each VLAN group and blocks all but one of the possible alternate paths within each spanning tree instance. MSTP enables formation of MST regions that can run multiple MST instances (MSTI). Multiple regions and other STP bridges are interconnected using one single common spanning tree (CST).

MSTP is fully compatible with RSTP bridges, in that an MSTP BPDU can be interpreted by an RSTP bridge as an RSTP BPDU. This not only enables compatibility with RSTP bridges without configuration changes, but also causes any RSTP bridges outside of an MSTP region to see the region as a single RSTP bridge, regardless of the number of MSTP bridges inside the region itself. For two or more switches to be in the same MST region, they must have the same VLANs to MST instance mapping, configuration revision number, and region name. Switches intended to be in the same MST region are never separated by switches from another MST region. If they are separated, the region becomes two separate regions.

This mapping can be done in the MSTP Instance Settings. Use this page if the system operates in MSTP mode.

To define MSTP, follow these steps:

Procedure

Step 1

Click Spanning Tree > MSTP > MSTP Properties.

Step 2

Enter the parameters.

  • Region Name—Define an MSTP region name.

  • Revision—Define an unsigned 16-bit number that identifies the revision of the current MST configuration. The field range is 0–65535.

  • Max Hops—Set the total number of hops that occur in a specific region before the BPDU is discarded. Once the BPDU is discarded, the port information is aged out. The field range is 1–40.

Step 3

Click Apply. The MSTP properties are defined, and the Running Configuration file is updated.