BBMD stands for BACnet Broadcast Management Device. Messages such as "Who-Is" and "I-Am" are
broadcast. Most routers, however, to not pass broadcast messages along. The BBMD solves this problem
by explicitly directing broadcast messages to a specific IP address.
A Broadcast Distribution Table (BDT) defines a list of IP addresses that the BBMD should send broadcast
messages to. It is important to note that a BBMD only forwards broadcast messages. It does not do full
routing. If you are attempting to connect two networks across a NAT router, you must get a full BACnet
Router to accomplish this. For this reason, the BDT has limited usefulness when only BBMD is present. The
BB2-7010 only includes BBMD, not full routing. Use the BB2-7030 if you need full routing.
If you have a remote BB2-7010 that needs to connect via router, including NAT router, to a local network,
use Foreign Device Registration. There will typically be a master device, such as operator station or other
front end, that includes BBMD. The IP address of this device is the one that should be given as the
BBMD address for foreign device registration.
Broadcast distribution will result in device discover, but you will not be able to read/write properties in the
remote device without full routing. Foreign device registration does result in being able to fully
communicate with the foreign device from the local network.
The screen shot below shows a BB2-7010 that has successfully registered with a BBMD at the IP address
shown.
13. BBMD Configuration
file:///C:/AAA_CSI/Literature/2015 User Guides/BB2-7010/BB2-7010 ...
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