Lan protocol - How to send messages to a GROUP?

To send a message to each bulb in a group you craft and send a unicast packet to each bulb in the group. The 16 byte ID is just a label on the bulb, the application handles all the multiplexing. Originally we did support talking to groups using broadcast messages, but on 802.11 networks broadcast messages are unreliable often reaching some bulbs later, and sometimes not at all. In the end our applications had to track group members and retransmissions to each member anyway, and when we switched to unicast the efficiency improved by leaps and bounds.

Not that I’m aware of.

Sending unicast messages directly to each individual bulb is hands down the best way to get the best synchronicity and response time. Make sure your application tracks the replies (or acks) from each message and resends it if it doesn’t get one. Of course the hard part here is tuning the timeout so that you resend fast enough, while not sending duplicates.