I'm interested in how anycast works. There are two ways how a transmitter sends a packet to the receiver. I'm interested in how anycast with controlled access works. How a destination host is chosen. Guess there should be a control terminal which distributes the packets. But how exactly this happens?
CloudFlare published a very informative blog post on how they're dealing with anycast. Only routing is involved. Each host is announcing a route via BGP and thus affecting the routing decision.
When a host goes down, the route is not announced so the router takes the next available route. Critical processes are also monitored and routes are announced or not depending on the server load.