Dell EMC SmartFabric OS10 User Guide Release 10.5.0

Use the debug spanning-tree bpdu command to monitor and verify that the MST configuration is communicating as configured. To ensure all necessary parameters match — region name, region version, and VLAN to instance mapping, examine your individual devices. Use the show spanning-tree mst command to view the MST configuration, or use the show running-configuration command to view the overall MST configuration.

MST flags for communication received from the same region

The MST routers are located in the same region. If the debug logs indicate that packets are coming from a Different Region, one of the key parameters does not match.

MST region name and revision

The configured name and revisions must be identical among all devices. If the region name is blank, a name was configured on one device and was not configured or was configured differently on another — spelling and capitalization count.

MST instances

Verify the VLAN-to-MST instance mapping using the show commands. If you see extra MST instances in the Sending or Received logs, an additional MST instance was configured on one router but not the others.

• View BPDUs in EXEC mode.

  debug spanning-tree bpdu

• View MST-triggered topology change messages in EXEC mode.

  debug spanning-tree events

View MST configuration

OS10# show spanning-tree mst configuration
Region Name: force10
Revision: 100
MSTI    VID
0       1,31-4093
1       2-10
2       11-20
3       21-30