I have a (large) site that has been running for a couple years or so now without any network trouble. It is SiteScan but you can think of it as WEBctrl. It has a little over seventy IP attached devices using the private IP range 192.168.168.x and there is no connection to another network. We are running BACnet/IP 47808 and network number 5600 with device instances in the range of 560xxx.
Just this week we had a trane system add themselves to the network with unknown bacnet information, they didn't coordinate with us.
Now we have dead module alarms, failures to download memory to modules and most importantly to the customer the graphics for the system take a very long time to populate with information. Seems to point to network trouble.
I am thinking that the trane system should have coordinated with us to at least match the BACnet network number with our system because it is on the same network. Also should have reviewd device instances to make sure there weren't any duplicates but I think that is unlikely due to the range we are using.
You all agree/disagree using two different BACnet netowrk numbers on the same network is going to cause trouble like this?