Viewing debug counters for ports in an MST instance

The show spanning-tree debug-counters instance ports command displays 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 this command to troubleshoot at a finer level the more general MSTP diagnostic information displayed in the 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

Displays debug counters for MSTP activity on the specified ports configured for VLANs in the specified MST instance.

instanceinstance-id: The valid values for instance-id are from 0 to 16, where 0 specifies the default MST (CIST) instance and 1 to 16 specify an MST instance.
portsport-list: 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-a8 or trk1-trk3. Separate individual ports and series of ports with a comma; for example, a2-a8, a20, trk1, trk4-trk5.

Viewing debug counters for a CIST and MST instance

The following example 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.

switch(config)# show spanning-tree debug-counters instance 0 ports a15

 Status and Counters - CIST Port(s) Debug Counters Information

  MST Instance ID : 0
  Port : A15

  Counter Name                Value      Last Updated
  --------------------------- ---------- ----------------- 
  Invalid BPDUs               0
  Errant BPDUs                0
  MST Config Error BPDUs      0
  Looped-back BPDUs           0
  Starved BPDUs               0
  Exceeded Max Age BPDUs      0
  Exceeded Max Hops BPDUs     0
  Topology Changes Detected   1         02/09/07 17:40:59
  Topology Changes Tx         3         02/09/07 17:41:03
  Topology Changes Rx         2         02/09/07 17:41:01
  Topology Change ACKs Tx     0
  Topology Change ACKs Rx     0
  TCN BPDUs Tx                0
  TCN BPDUs Rx                0
  CFG BPDUs Tx                0
  CFG BPDUs Rx                0
  RST BPDUs Tx                0
  RST BPDUs Rx                0
  MST BPDUs Tx                5         02/09/07 17:41:03
  MST BPDUs Rx                173540    02/13/07 18:05:34

Viewing debug counters output for one port in an MST instance

The following example shows spanning tree debug-counters instance ports command output for one port in an MST instance.

switch(config)# show spanning-tree debug-counters instance 2 ports a15

 Status and Counters - MSTI Port(s) Debug Counters Information

   MST Instance ID : 2
   Port : A15

   Counter Name                Value      Last Updated
   --------------------------- ---------- ----------------- 
   Starved MSTI MSGs           0
   Exceeded Max Hops MSTI MSGs 0
   Topology Changes Detected   1          02/09/07 17:40:59
   Topology Changes Tx         3          02/09/07 17:41:03
   Topology Changes Rx         2          02/09/07 17:41:01
   MSTI MSGs Tx                5          02/09/07 17:41:03
   MSTI MSGs Rx                173489     02/13/07 18:03:52