Administrator Guide

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 Congurations
To debut and verify MSTP conguration, 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 Congurations
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 conguration, use the show spanning-tree mst commands.
To view the overall MSTP conguration on the router, use the show running-configuration spanning-tree mstp in EXEC
Privilege mode.
To monitor and verify that the MSTP conguration 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 ags 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 “Dierent Region”? If so, one of the key parameters is not matching.
• MSTP Region Name and Revision.
• The congured name and revisions must be identical among all the routers.
• Is the Region name blank? That may mean that a name was congured on one router and but was not congured or was
congured dierently on another router (spelling and capitalization counts).
• MSTP Instances.
• To verify the VLAN to MSTP instance mapping, use the show commands.
• Are there “extra” MSTP instances in the Sending or Received logs? This may mean that an additional MSTP instance was
congured on one router but not the others.
The following example shows the show run spanning-tree mstp command.
Dell#show run spanning-tree mstp
!
protocol spanning-tree mstp
name Tahiti
revision 123
MSTI 1 VLAN 100
MSTI 2 VLAN 200,300
The following example shows viewing the debug log of a successful MSTP conguration.
Dell#debug spanning-tree mstp bpdu
MSTP debug bpdu is ON
590
Multiple Spanning Tree Protocol (MSTP)