Multiple Instance Spanning-Tree Operation
Troubleshooting an MSTP Configuration
Displaying Debug Counters for Ports in an MST
Instance
The show spanning-tree debug-counters instance ports command allows you to display the aggregate values of all MSTP debug counters maintained on one or more ports used by a specified spanning-tree instance. These aggregate values are a summary of information collected from the specified ports that have VLANs assigned to the specified instance.
Use the show spanning-tree debug-counters instance ports command to troubleshoot at a finer level the more general MSTP diagnostic information displayed in show spanning-tree debug-counters instance command output when you suspect unauthorized MSTP activity on one or more MST ports in an MST instance.
Syntax: show spanning-tree debug-counters instance <instance-id> ports <port-list>
This command displays debug counters for MSTP activity on the specified ports configured for VLANs in the specified MST instance.
The valid values for instance <instance-id>are from 0 to 16:
•0 specifies the default MST (CIST) instance.
•1 to 16 specify an MST instance.
The ports <port-list>parameter specifies one or more MST ports or trunk ports.
In the port list, enter a series of ports by separating the first and last ports in the series with a dash (-); for example, a2-a8or trk1-trk3. Separate individual ports and series of ports with
acomma; for example, a2-a8, a20, trk1, trk4-trk5.
The following examples shows sample output of the show spanning-tree debug- counters instance ports command for both the CIST (default MST instance 0) and an MST instance (instance 2) on port A15. For a description of each counter, refer to Table 4-1 on page 4-66.