Aruba - Controllers

Aruba Controllers - as other brands of controllers - serve as a single point of configuration and monitoring of access points.
Aruba have som stand-alone APs (Instant APs) - but all other APs will not function without a controller. When the AP boots it looks for the controller (on the same network as the AP, either L2 or L3), and asks for its configuration - when controller accepts the AP as one of its own - it will push configuration to the AP which then completes boot and start serving clients.
The benefit is that you can change configuration on all APs from just one location, you can troubleshoot connectivity and performance problems from one location, as opposed to do this one time on every AP you've got.
You will also get better use of radio spectrum since the controller controls all APs and can dynamically change channels all the way.

When buying Aruba controllers look at how many APs they can serve at max. The MBC 650 have 16 APs max, and if you need 17 - you need to buy MBC 3200 - you cannot upgrade a controller beyond its AP limit.

thanks
I have few clarifications.
For making any changes to any AP do i need to make changes at the controller & then push the configuration to the AP or i can make changes to the AP directly.

Do controller have all the configuration backup of the APs.?

Yes - you can do very little on APs - All you can do on APs is clear configuration. All settings is done on controller - which instantly push these to APs
COntroller has all configuration for all APs. Need a new AP - connect it and a couple of minutes later, it's configured and up and running

do any one has the feature comparison between Aruba wireless network & Cisco wireless network solution.

Thanks