BACnet Explorer Start-up Guide
Page 22 of 24
Appendix B References
Appendix B.1. Understanding FDR
The BACnet Explorer doesn’t allow FDR, local IP and MSTP to co-exist because there is no guarantee
that two distinct BACnet networks will have unique Device Instances or Network Numbers. (Unique
Device Instances and Network Numbers are a requirement for BACnet to function properly). If local and
remote options were allowed concurrently, the BACnet Explorer would connect two networks that are
probably not designed to work together. Forcing this situation would create extremely difficult to diagnose
problems.
Appendix B.2. Understanding BACnet BBMD and NAT Routing
The BACnet Explorer does not support NAT routing. However the BACnet Explorer must have the
external IP Address and IP Port that the NAT router assigns to it, because these are inserted into the
BACnet/IP BVLC header as the source IP Address which a remote recipient can use to reach the BBMD
(BACnet Broadcast Management Device). This is necessary because the messages are distributed again
by a remote BBMD, and the remote recipient of a distributed broadcast needs to reach the originator of
the broadcast.
Figure 27: BBMD Scenario 1
– Interconnected IP Network
