Spanning Tree
VLANs to a MSTP Instance
231 Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x
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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 theVLANs to a MSTP Instance page.
Use this page if the system operates in MSTP mode.
To define MSTP:
STEP 1 Click Spanning Tree > STP Status and Global Settings.
STEP  2 Enable MSTP.
STEP  3 Click Spanning Tree > MSTP Properties.
STEP  4 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 from 0 to 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 from 1 to 40.
• IST Master—Displays the regions master. 
STEP  5 Click Apply. The MSTP properties are defined, and the Running Configuration file is updated.
VLANs to a MSTP Instance 
The VLAN to MSTP Instance page enables you to map each VLAN to a Multiple Spanning 
Tree Instance (MSTI). For devices to be in the same region, they must have the same mapping 
of VLANs to MSTIs. 
NOTE The same MSTI can be mapped to more than one VLAN, but each VLAN can only have one 
MST Instance attached to it.
Configuration on this page (and all of the MSTP pages) applies if the system STP mode is 
MSTP.
Up to 16 MST instances can be defined in addition to instance zero.