There are presently two ways that BACnet can be “spoken” over the public network, and these two methods are prescribed in the BACnet standard in Annex H and Annex J (BACnet/IP). For Annex H communication, a BACnet message destined for a remote BACnet network that must traverse a public network is sent by a tunneling mechanism. A device called a “BACnet/Internet Protocol Packet-Assembler-Disassembler” (B/IP PAD) exists on both networks, keeps track of all other B/IP PADs, and inspects the destination network (DNET) field of packets to see if they are destined for a remote network. If so, the B/IP.
