RSTP Troubleshooting for BACnet/IP Controllers

[David_Purser]

Issue

BACnet/IP controllers are not configured in RSTP Mode by default, therefore must be configured during installation. Having RSTP Mode disabled by default allows one to connect BACnet/IP controllers to any switch, even with port security configured to detect BPDU packets and disable the port.

Product Line

EcoStruxure Building Operation, TAC IA Series

Environment

• Multi-purpose Controller (MP-C)
• Multi-purpose VAV (MP-V)
• Room Controller
• IP-IO
• I/A Series N4 Jace8000
• SmartX IP Driver for Niagara

Cause

RSTP protocol requires that controllers, switches, and network architecture are configured to ensure the protocol will operate as expected. 

Resolution

Setting RSTP Mode for BACnet/IP Controllers

ALL devices in the RSTP loop MUST BE IN RSTP MODE to function properly. This is not a huge issue because during startup you can unplug 2nd side of the loop and it will function properly in a daisy chain.

1. Ensure the SmartX Controllers are configured correctly Configuring BACnet/IP Controller Device Settings
1. A factory or network reset returns the RSTP setting to Disabled.
2. Important: Whenever you change RSTP settings, the controller MUST be WARM START. If you fail to perform this restart, the BACnet/IP controller will continue communicating using its previous RSTP settings. 'Activate IP Changes' does not affect RSTP mode.
2. Ensure the switch is configured correctly per Configuring RSTP on a Managed Switch for SmartX IP Controllers. If asked to review this for a case, please provide PSS screenshots from the switch configuration page(s). 
   • Bridge Priority = 4096
   • Hello Time = 2 sec
   • Max Age = 40  (40 is the maximum value allowed by the protocol. Default is 20)
   • Forward Delay = 21 sec
   1. Bridge Priority Considerations
      1. Change Bridge Priority by adding 4096 as switches get further away from AS. (8192, 12288, 16384, 20480, 24576, 28672)
      2. DO NOT set the priority as 32768 or higher because that is the built-in Bridge Priority of BACnet/IP Controllers.
      3. First, configure the Root Bridge Switch (closest to the Automation Server) settings. Then, configure the additional Switches in order of increasing Bridge Priority.
   2. Plug in 2nd side of the RSTP Loop
   1. If all devices stay online, then it is working properly. Now test line breaks or controllers that are powered off.
   2. If all devices go offline and/or the switch LED is flashing rapidly, then go to RSTP Troubleshooting.

Managed Switch Troubleshooting

1. Consult the documentation or contact the vendor or manufacturer to assist with configuration for the items below.
2. Ensure the switch is IEEE 802.1D - 2004 capable. BACnet/IP Controller Networking Term Definitions RSTP Ring mentions the Rapid Spanning Tree Protocol is specified in IEEE 802.1D - 2004.
3. Ensure the firmware is up-to-date by contacting the vendor or manufacturer or downloading it from its website.
4. Ensure ports not participating in RSTP are configured as Edge Port, Admin port, or have STP disabled. Nomenclature for those settings on your specific managed switch may vary.
5. Adding BACnet/IP controllers to site-managed switches, work with Local IT to add these devices to their network. They will need to work with their switch vendor/manufacturer/support group to ensure the configuration of those switches because it could be more complex than changing the minimum recommended four settings above. Also, since RSTP Protocol is limited to Max Age = 40 (hops including site switches and BACnet/IP controllers), each loop's size may be limited based on their site switch network configuration and architecture. 
6. Determined the proper configuration (or disable) for the following features.
   1. DHCP snooping
   2. Dynamic ARP inspection
   3. Denial-of-service (DOS) mitigations
   4. BPDU Guard
   5. BPDU Filter

RSTP Troubleshooting

Check each BACnet/IP Controller -> Diagnostics -> Device Report to confirm in RSTP Mode

1. MANUAL CHECKOUT
   1. Double-click MP - Diagnostics Files - Device Report
   2. It will open in the default text editor
   3. Review the Device Settings section near the bottom.
   4. In firmware 1.00.0x, the report should report RSTP Mode: Enable
   5. In firmware 2.00.0x or higher, RSTP: Enabled and RSTP Status: Operational
   6. If it reports disabled, then perform Setting RSTP Mode for BACnet IP Controllers Step 1 until RSTP is working properly.
2. USE SEARCH & EVENTS
   1. EBO 2.x MP Device IP and Settings.xml for EBO 2.0 as it only includes MP controllers
   2. EBO 3.x SmartX Device IP and Settings.xml for EBO 3.x or higher
   3. Import attached search
3. USE RSTP STATUS GRAPHIC IN WEBSTATION
   1. MUST BE EBO 3.1 or higher which includes ClientAPI support
   2. Frontline Fridays Episode 02 - Rapid Spanning Tree Protocol (RSTP)
      1. Date: 2022-11-11
      2. Mike Botens posted the following in the thread:
         1. RSTP Status TGML dated 2022-11-09
         2. PDF of the presentation
   3. Fusion Fridays - Session 07 ​​​​
      1. Date: 2020-05-28
      2. The start of the video shows the graphics page in use
      3. RSTP Status.zip is downloaded via the link below the video.
      4. Extract the TGML and drop it on the AS to import. The suggestion is to store TGML directly under the AS to help with navigation in Webstation.
      5. bind Network to the BACnet/IP network with the BACnet/IP Controllers. (You may need a second TGML page if BACnet/IP controllers are on Primary and Secondary IP)
      6. Run from web browser via WebStation because utilizes ClientAPI

KNOWN ISSUES

• Offline controllers that are scattered are NOT an RSTP issue. Check to see if there is a possible DHCP issue by verifying controllers are still at their AUTO-IP address (IP 169.254.nnn.nnnn Subnet Mask 255.255.0.0). RSTP communications issues affect the entire RSTP loop or one contiguous group of controllers.
• Factory Reset or controller replacement should leave one ethernet cable unplugged until configured for RSTP per these articles: Replace a BACnet/IP Controller in an RSTP Ring Network Workflow and MP Controller Reset Modes
• If BACnet/IP Controller Device Report OR RSTP Graphic reports RSTP Status: Changes Pending instead of RSTP Status: Operational, disable RSTP Mode, Warm Start, re-enable RSTP Mode, Warm Start, and check again.
• SmartX is now SpaceLogic.
• KNOWN ISSUES with Firmware affecting RSTP:
  • If Firmware 3.02.01 is installed, please upgrade to 3.02.02.
  • RSTP not performing as expected with Static IP addressing
  • RSTP does not work well on RPC HW RPC-16-B HW revision 6