I've seen this too - it happens every time an iOS device goes to sleep. In this case, I'm running an iPod Touch and an iPad Air with iOS7, connecting to a new RB951G with the latest OS. It's running as a switch with wireless AP, as routing is provided by a RB2011 in another rack. Syslog fills up with this:
2 192.168.1.42 wireless,info B0:34:95:xx:xx:xx@wlan1: disconnected, extensive data loss
39 192.168.1.42 wireless,info wlan1: data from unknown device B0:34:95:xx:xx:xx, sent deauth
1 192.168.1.42 wireless,info B0:34:95:xx:xx:xx@wlan1: connected
In the example, there were 39 deauth requests sent within a few minutes, which completely shut down the wireless portion of my network.
Interestingly enough, when I watch the signal indicators in Webfig/Quick Set, I see the Apple devices actually drop off the network - that is, IP address disappears from the list. The lease is still good - they have static DHCP leases assigned by a remote router. Other devices, such as an android phone, will sleep but do not reject their address. All wireless devices are in ACL, and ACL is in use.
I seem to remember something from the original iPad days where networks would be flooded with address requests from devices, perhaps this has something to do with it? In any event, I can't use the device as is. It's currently boxed up for return, but I'd love to keep it. Is there a fix?