The broker server acts as a mediator for all the servers, you’d connect all media servers to this broker as well chat servers. You’d keep track of servers, rooms, broadcasts, subscriptions and more through this server.
A bit tough to explain but see it as if we had one room on two servers we’d need a mediator, we’d need to send the message to a server to fan it out.
So in this setup, broker calls every shot and may perform tasks like,
CloseBroadcaster, CloseConsumers all sorts and will need to know which server consumed/produced/etc.
As far as I’ve seen, there’s no solution ready-made for this type of stuff, so it’s all going to be custom generally for your app.