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How to troubleshoot spanning tree topology changes on SecureStack, N-Series and S-Series

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TitleHow to troubleshoot spanning tree topology changes on SecureStack, N-Series and S-Series
Objective
How to troubleshoot spanning tree topology changes on SecureStack and N/S-Series
Environment
  • N-Series - All firmware versions
  • S-Series - All firmware versions
  • SecureStack - Firmware version 06.61.xx and later
Procedure
  • On N/S-Series, review command output from show spantree stats active to see "Topology change count" and "Time Since Top Change":
C5(su)-> show spantree stats  active
.
.
Topology Change Count      - 1
Time Since Top Change      - 0 days 2:01:58
Max Hops                   - 20
 SID   Port         State              Role          Cost        Priority
 ---   ----------   ----------------   -----------   --------    --------
 0      ge.1.46      Forwarding         Root          20000       128
  • On N/S-Series, review "show spantree debug port *.*.* active" to find if we have any high counts on the section "Ports with Received TC BPDUs" section:
S-Series(su)-> show spantree debug port *.*.* active
.
.
Ports with Received TC BPDUs         Count
------------------------------------------------------------
ge.2.2                                  107
ge.2.40                                 5
  • On N/S-Series and Securestack, review the same show spantree debug port *.*.* active output to look for any type of TC or TCN received, or invalid / disputed or Message expiration  to help trace down any problematic ports:​
C5(su)-> show spantree debug port *.*.* active

STP Diagnostic Port Counters for SID 0 Port ge.1.46
---------------------------------------------------------
Port Role                  - Root
Message Expiration Count   - 0
Invalid BPDU Count         - 0
STP BPDU Rx Count          - 0
STP BPDU Tx Count          - 0
STP TCN BPDU Rx Count      - 0
STP TCN BPDU Tx Count      - 0
STP TC BPDU Rx Count       - 907
STP TC BPDU Tx Count       - 34
RST BPDU Rx Count          - 0
RST BPDU Tx Count          - 0
RST TC BPDU Rx Count       - 0
RST TC BPDU Tx Count       - 0
  • On N/S-Series, enable movedaddrtrap logging on all ports to determine if any type of loop is occurring, then review moved mac addresses through logging buffer:
S-Series(su)-> set movedaddrtrap enable
S-Series(su)-> set movedaddrtrap *.*.* enable
S-Series(su)-> show logging buffer

AddrNtfy[1]MAC: 00-11-22-33-44-55: moved to port lag.0.4, FID 1 
AddrNtfy[1]MAC: 00-11-22-33-44-55: moved to port lag.0.4, FID 1 
AddrNtfy[1]MAC: 00-11-22-33-44-55: moved to port ge.1.22, FID 1
  • Look for the same mac address moving to different ports, which at a slow rate of creation may be normal such as roaming wireless users
  • Moved mac addresses at a rapid rate and not with wireless client mac addresses would typically indicate an issue
  • On SecureStacks, It may be useful to elevate logging level of STP if on 06.42.xx code or earlier as we did not introduce spantree debug commands until 06.61.xx code:
  • On SecureStack switches the following commands provide 3 State changes of Discarding, Learning and Forwarding, and the commands are not STP changes but port state changes due to link down / link up
  • On SecureStack switches when using the same logging commands, you will still see the messages below but when a Topology Change Notification has happened, one of the messages would include a "TCN" signifying a Topology Change Notification at the end of the log.
C5(su)-> set logging default severity 8
C5(su)-> set logging application STP level 8
C5(su)-> show logging buffer

This is from manager 1 %% Setting Port(33) instance(0) State: DISCARDING
This is from manager 1 %% Setting Port(33) instance(0) State: LEARNING
This is from manager 1 %% Setting Port(33) instance(0) State: FORWARDING
Additional notes
There are additional FlexViews in Netsight Console in the flexview folder "Bridge" that can be useful in large network environments when troubleshooting Spanning Tree

and to view a video on the use of those fllexviews see the YouTube link below:

http://youtu.be/t6h475I6CAo

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