We recently upgraded our MR36 fleet to firmware version 30.5. I don't know if it's coincidental, a result of the upgrade, or if it's always been like this and I just now noticed it, but the APs have gotten "chatty" with communicating with Meraki infrastructure, to the tune that traffic to Meraki sites is now our 4th highest bandwidth utilization according to our content filter (we have over 1,000 MR36's deployed across our network).
It seems to be in bursts, but traffic will average 500MB - 1GB per day per AP, with most traffic going to usw.nt.meraki.com and use.nt.meraki.com. There is more upload traffic than download, around a 2-1 ratio.
Has anyone else noticed this? Is this normal?