(Step 3)
interface vlan 100
tagged 1/0/31
tagged 1/0/32
exit
interface vlan 200
tagged 1/0/31
tagged 1/0/32
exit
interface vlan 300
tagged 1/0/31
tagged 1/0/32
exit
Debugging and Verifying MSTP Configurations
To debut and verify MSTP configuration, use the following commands.
• Display BPDUs.
EXEC Privilege mode
debug spanning-tree mstp bpdu
• Display MSTP-triggered topology change messages.
debug spanning-tree mstp events
Examples of Viewing MSTP Information
To ensure all the necessary parameters match (region name, region version, and VLAN to instance
mapping), examine your individual routers.
To show various portions of the MSTP configuration, use the show spanning-tree mst commands.
To view the overall MSTP configuration on the router, use the show running-configuration
spanning-tree mstp in EXEC Privilege mode.
To monitor and verify that the MSTP configuration is connected and communicating as desired, use the
debug spanning-tree mstp bpdu command.
Key items to look for in the debug report include:
• MSTP flags indicate communication received from the same region.
– As shown in the following, the MSTP routers are located in the same region.
– Does the debug log indicate that packets are coming from a “Different Region”? If so, one of the
key parameters is not matching.
• MSTP Region Name and Revision.
– The configured name and revisions must be identical among all the routers.
– Is the Region name blank? That may mean that a name was configured on one router and but was
not configured or was configured differently on another router (spelling and capitalization counts).
• MSTP Instances.
– To verify the VLAN to MSTP instance mapping, use the show commands.
Multiple Spanning Tree Protocol (MSTP) 607