B/IP Broadcast...

In addition to devices talking directly to each other, there needs to be a mechanism to broadcast a message so that all B/IP devices receive it. We will use the existing standard for broadcasting UDP packets.

A UDP broadcast packet is 'sent' to an IP address with the subnet of the broadcasting device and all 1's in the host portion. For example, if a device has an address and a subnet mask, it can use the broadcast address Although most networks also allow the use of the IP broadcast address, we have ruled this out for BACnet/IP because of some IP protocol stack limitations that certain implementors have encountered.

The BVLCI indicates that this is an Original-Broadcast-NPDU.


The NPCI shows that this is not "data expecting a reply," i.e., a broadcast.