Oh! That seems too simple. 🙂 Silly me. I guess I was thinking that wouldn’t work because any iTunes clients would only look for/connect to servers that offer this on port 3689 (the iTunes default). Obviously I’m mistaken. Does the mt-daapd server announce (broadcast) it’s availability/existence via tcp/ip or udp? Including, of course, the port it’s running on…? (Just because I’m curious.)
Yup, that’s what mdns does. iTunes just asks the network who is running daap services, and the server responds with the ip address and port and whatnot — so it’s the mdns component that does that. And by way of information, it’s multicast as opposed to broadcast.
wrt to running mt-daapd on multiple ports, you’ll want to have different database directories (db_parms), different ports, and different log files. That should really be it.