Issue
Need to perform a diagnostic verification as a preventative measure during routine maintenance or reactively in response to cabling that is causing RSTP issues.
Product Line
EcoStruxure Building Operation
Environment
- Multi-purpose Controller (MP-C)
- Multi-purpose VAV (MP-V)
- Room Controller (RPC)
- IP-IO
Cause
Cabling or cabling terminations between controllers in the RSTP loop can cause issues.
Resolution
- Reference RSTP Troubleshooting for BACnet/IP Controllers - Schneider Electric Community to ensure that:
- the managed switch is appropriately configured for RSTP
- all SpaceLogic controllers, on the RSTP loop, report RSTP Status = Operational
- Leave one side connected to the managed switch, plug the free end into the laptop running Wireshark, and take a capture.
- Ensure both ends are unplugged
- Plug the other side into the managed switch, plug the free end into the laptop running Wireshark, and take a capture.
- Evaluate based on the information below
- If either evaluation fails, check the cables based on Message Age using a cable tester. It is optional but highly recommended to use a cable tester that displays cable length, as it tends to be more accurate and can point out failures that other testers may report as passing.
- If it passes the evaluation on both ends, then one can plug both ends into the managed switch
Evaluation
This capture shows a topology change (TC + Root) in RSTP, then settles out to a consistent Root Bridge Priority and Message Age. Your capture should only show a topology change when Wireshark is capturing on one end and the other end is connecting/disconnecting from the managed switch.
Review the following fields:
- Root Bridge Priority - should be consistent and show the Priority of the Root Bridge. The root bridge can be the switch to which the RSTP loop is connected or a managed switch upstream.
- If it shows 32768, then another SpaceLogic controller assumed the root because it is not communicating properly back to the root bridge. (See Message Age Note)
- Message Age - should be consistent and show the expected number of controllers away from the root bridge.
- When Root Bridge Priority is 32768, you can use Message Age to determine how many controllers away the issue is occurring, and check the cabling connected to or near that controller.
