We've been experiencing some interesting quirks getting BACnet talking between devices. We have tested between two separate Mango servers, and thought we'd resolved the issue, but when a customer ran into it, (Mango as BACnet publisher, 3rd party software client) I had to dig back in.
To make a long story medium, our EdgeServer has multiple interfaces:
- eth0 (Device Area Network) for industrial devices (PLCs, etc)
- eth1 (LAN/WAN) for interwebz routing
- wwan0 (4GLTE) for wireless interwebz
As I was exploring, I noticed that default routes for both eth1 and wwan0. This is to be expected, since both get gateway settings from DHCP. What was unexpected was how the BACnet publisher was horribly unreliable when the wwan0 route had a lower metric (higher priority) than the eth1 route (client is on the LAN with eth1, same subnet). There is no way the gateway route should even come into play when there is an explicit route for the subnet. But when I changed the priorities of the default routes, the results speak for themselves.
Any thoughts or explanations for this behavior? Suggestions? Has anyone come across this?