Spanning Tree Protocol
Configuring Multiple Spanning Tree
Cisco 220 Series Smart Switches Administration Guide Release 1.1.0.x 155
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• Max Hops—Enter 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. The default is 20. 
STEP  3 Click Apply. The MSTP properties are defined, and the Running Configuration file 
is updated.
Mapping VLANs to MST Instance
Use the VLAN to MSTP Instance page to map VLANs to MSTP instances. For 
devices to be in the same region, they must have the same VLAN to MSTP 
instance mappings. 
NOTE The same MSTP instance can be mapped with more than one VLAN, but each 
VLAN can only have one MSTP instance attached to it.
Up to 16 MSTP instances can be defined on the switch. For those VLANs that are 
not explicitly mapped to one of the MSTP instances, the switch automatically 
maps them to the Core and Internal Spanning Tree (CIST) instance. The CIST 
instance is MSTP instance 0.
To map VLANs to MSTP instances: 
STEP 1 Click Spanning Tree > VLAN to MSTP Instance. 
STEP  2 To add VLANs to an MSTP instance, select the desired MSTP instance and click 
Edit. 
STEP  3 Enter the following information: 
• MSTP Instance ID—Select the MSTP instance.
• VLANs—Enter the VLANs being mapped to this MSTP instance.
• Action—Select either Add or Remove to map or remove the VLANs to or 
from the MSTP instance.
STEP  4 Click Apply. The VLAN-to-MSTP instance mapping is defined, and the Running 
Configuration file is updated.