Firmware update procedure for always on AP's
I would like to know how the update procedure works for AP's that are always on.
I have an ap running a fictive firmware version, let's call it AA. My AP is always on, so when firmware BB is released my ap downloads the new firmware, and put's it on it's second partition. If my AP reboots, it will start up with firmware BB, correct?
What if it is never rebooted? Will it keep running firmware AA, or is there a timeout, X seconds from sucessfully downloading firmware BB, ap will reboot and install it?
What will hapen if firmware CC is released? My AP is running firmware AA, and it has downloaded firmware BB. Must it reboot and install the firmware that is downloaded, or will it overwrite firmware BB with firmware CC?
Most AP's are always on, and scheduled reboots are once a year. If AP's don't overwrite whatever firmware they have downloaded, when a new firmware is released, we could end up with AP's running very very old firmwares.