Detected Circular Networks

Overview

• Circular networks happen when you have two or more routes to the same controller.
• Look at the Hop Count value of every packet. Would need to be BACnet IP.
• If the Hop Count drops below 10, it gets flagged as a Circular Network.
• Will always also trigger the Low Hop Count check.
• Could happen with BACnet MS/TP, but it is rarer.
• Typically, the routes are BACnet/IP and BACnet/Ethernet and both are communicating on both networks.

Why it fails

• Checked both boxes on the manufacturer’s controllers.
• Migrated a site from Ethernet to IP.
• Kept the Ethernet network because it is easy to connect to.

How to fix it

• Circular Network will be causing such a traffic storm you won’t be able to reach any of the controllers.
• Need to unplug one of the problematic controllers, isolate it from the network, and reconfigure it.
• You can then add it back onto the network.