The BBMD processing is now extended to forward broadcast messages not only to remote subnets but also to foreign devices. There are two cases where this happens:
We have already covered the situation where this broadcast message is forwarded to peer BBMD subnets. But the foreign device will never receive the broadcast message so it must be sent to it directly so:
Upon receipt of a local broadcast message, a BBMD shall construct a Forwarded-NPDU message and send it to each foreign device currently in the BBMD's FDT.
A foreign device has no way to broadcast a message to the other devices on the B/IP network it has joined so it relies on its BBMD to make sure it gets to any other registered foreign devices as well to all the other subnets.
Upon receipt of a BVLL Distribute-Broadcast-To-Network message from a foreign device, the receiving BBMD shall transmit a BVLL Forwarded-NPDU message on its local IP subnet using the local B/IP broadcast address as the destination address. In addition, a Forwarded-NPDU message shall be sent to each entry in its BDT as described above ... as well as directly to each foreign device currently in the BBMD's FDT except the originating node. If the BBMD is unable to perform the forwarding function, it shall return a BVLC-Result message to the foreign device with a result code of X'0060' indicating that the forwarding attempt was unsuccessful.