I was recently asked for help to block Airdrop in a WLAN, there was a cause where a person transferred inappropriate content to another individual while being in an educational institution. Since Airplay can be blocked via mDNS profiles whether we assign it statically under the SSID settings or via attributes with a AAA Server, that discovery and traffics pass through the Wireless LAN Controller.
However, AirDrop is a different story, if you have used AirDrop before you know that as soon as you enable it, both, WiFI and Bluetooth are enabled. You may think that you need to be connected to your WiFi to be able to use it, however here is how it works..
Bluetooth: It is used to broadcast, discover, and negotiate connections to other AirDrop compatible devices.
WiFi: It is used to transfer data (point-to-point).
So, even if you are not connected to your home wifi router, or your company WiFi, the file transfer will happen via WiFi in a point to point connection between devices, no need of an AP/WLC.
If you want to test this, here is what you need to do.
Start AirDrop on both devices.
Try to transfer a file, AirDrop option will show you the device nearby, at this point, turn off Bluetooth on the other device, and you will see that the device will disappear from the device you were going to make the transfer from.
Enable Bluetooth back on the receiving device, it will be found again by the transmitting device.
Disconnect both devices from any WiFi network, if necessary remove/forget the SSID already saved on your devices, make sure they are not connected to any WiFI.
Start Airdrop on both devices.
Transfer a file.
The transfer was successful.
No need of an Access Point, communication happens point to point.
So, basically, since all communications happen between the devices, the WLC is not aware of that, and there is not way to block that traffic.
I know this might no be a big discovery for many, but I know some could be struggling with the idea of using mDNS Profiles to block it.
Apparently there is a way to detect Airdrop with Cisco MSE and wIPS, but I have not tested this yet.
I hope this can save you some time and thank you for reading.