Matthew Prince von cloudflare.com hat eine gute Zusammenfassung zum Thema Loadbalancing über Anycast veröffentlicht. Leider ist die Lösung nicht für alles nutzbar, er beschreibt aber sehr gut was möglich ist bzw. was beireits bei CloudFlare eingesetzt wird.
[...] Using Anycast, each server within each of CloudFlare's data centers is setup to receive traffic from any of our public IP addresses. The routes to these servers are announced via the border gateway protocol (BGP) from the servers themselves. To do this we use a piece of software called Bird. (You can tell it's an awesomely intense piece of networking software just by looking at one of its developers.) While all servers announce a route across the LAN for all the IPs, each server assigns its own weight to each IPs route. The router is then configured such that the route with the lowest weight is preferred.
If a server crashes, Bird stops announcing the BGP route to the router. The router then begins sending traffic to the server with the next-lowest weighted route. We also monitor critical processes on each server. If any of these critical processes fails then it can signal Bird to withdraw a route.[...]