(Step 3)interface vlan 100tagged 1/0/31tagged 1/0/32exitinterface vlan 200tagged 1/0/31tagged 1/0/32exitinterface vlan 300tagged 1/0/31tagged 1/0/32exitDebugging and Verifying MSTP ConfigurationsTo debut and verify MSTP configuration, use the following commands.• Display BPDUs.EXEC Privilege modedebug spanning-tree mstp bpdu• Display MSTP-triggered topology change messages.debug spanning-tree mstp eventsExamples of Viewing MSTP ConfigurationsTo ensure all the necessary parameters match (region name, region version, and VLAN to instancemapping), 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-configurationspanning-tree mstp in EXEC Privilege mode.To monitor and verify that the MSTP configuration is connected and communicating as desired, use thedebug 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 thekey 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 wasnot 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) 525
