If you have activated the BBMD function on the gateway in the BACnet configuration, the BBMD button will appear in the System->Manage menu. When you click on the BBMD button, a popup window with two tables in two tabs opens.

BDT table

The broadcast distribution table (BDT) lists the BBMDs on the network. Each BBMD on each network should (but do not have to) have the same broadcast distribution table. The subnet mask is a bit mask that applies against the BBMD address. Combining the two allows the gateway to find the address to send broadcast packages. Unless you have routers that permit remote broadcasts to their local networks (rare), you’ll need to broadcast directly to the BBMD. Because the gateway is BBMD and BACnet device, you must also insert the gateway's IP address into the BDT table!

FDT table

The foreign device table (FDT) shows a list of foreign devices that have registered on the CB-200 gateway. This table is read only.