No sure why someone want to reboot his APs every day but here my scenario.
Upgrade a controller pair to a newer release - set APs to controlled upgrade - so the APs don't upgrade to the new version and there is no service outage.
Then disable controlled upgrade and enable "AP Maintenance Cycle" so the APs reboot during the night (off-peak hours) to load the new software.
I've tried it in my lab and I don't like/unterstand the behavior.
In my lab setup I have only 15APs and only one with clients connected.
So in "phase#1" (= reboot APs with no connected clients) 14 of the APs reboot.
Before the APs were loaded with the new image and up&running also the AP with clients connected started the reboot.
Could you please explain it in more detail.
I.e. why the duration of 1-6 hours.
A AP need about 2 minutes to reboot and connect again to the controller.
Let's assume a C5210 with 900APs.
In phase#1 (no clients connected) let's say 1/3 have no clients and restart.
Then without any waiting time phase#2 is started and 100APs are in this category and reboot.
Next phase#3, my channel plan is 1/6/11 which would mean 3 groups with a 2minute waiting time between the groups.
Result is that all APs have restarted in timeframe of 10minutes.
My expection was that if I set the duration to 1hour that for example 15minutes are reserved for phase#1 - if some clients roam to another AP and so the AP has no clients connected.
Then another 15minutes to wait whether a AP would fit in phase#2 and the rest is for phase#3.
The conclusion is that this function is not useful in my scenario.
Or is my setup to small to see the "real" behavior of the feature.
Any whitepapers that explain the details/timers.