You posted this question in the controllerless forum. Is your question about Instant (controllerless) or controller networks?
If you have many Aruba Instant clusters, you should have a look at Aruba Central (cloud management) or Aruba Airwave if you prefer on-premise solutions.
In case of controllers, you probably want to look at the ArubaOS 8 architecture which as a Mobility Master, which does what you describe. Check here for the ArubaOS 8 Fundamentals Guide.