AP reboot & image download

[Bob Greer]

Hi there,

Thanks for reading!

We have a new site with 3800 APs which are flex connected to a remote location's WLC 2504.  The remote location had power issues which took the HA controllers offline for hours.  Locals rebooted the APs as a troubleshooting test.  Once power was restored, the APs joined but then took 75 minutes to download software from the WLC over the WAN.

Is this behavior a default which can be edited or something I have to live with?

Thanks again!

Bob

[Haydn Andrews]

Make sure that all the controllers that the APs can register to are running the same software version.

This is for APs with primary/ secondary/ tertiary controllers configures

Controllers in the mobility group same mobility group

Controllers that DNS or DHCP Option 43/60 points to for those APs

Controllers on the same broadcast domain as the AP.

If this is correct the APs should not need to pull down a new image if they reboot. They only get a new image when the WLC they are registering to is different to the one they are running.

Side not, you can configure a master AP under a Flex connect group that will then download a new image and distribute it to the APs in the AP group when you do a controller code upgrade. This will reduce the load required on the WAN as only one AP will download it accross the WAN

Reference to this is here: https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_010010001.html

[Haydn Andrews]

Add to this if all WLCs are running the same code that was on the APs then this sounds like a bug and you might want to raise a TAC case

[Leo Laohoo]

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@Bob Greer wrote:

Once power was restored, the APs joined but then took 75 minutes to download software from the WLC over the WAN.

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I think I know the reason why. 

The controller was probably configured to boot the secondary image after a reboot.  Let's say the WLC has two images:  Primary is 8.5.140 and the Secondary was 8.3.143.0. 

So when the controller came online, it loaded 8.3.143.0.  

When the APs came up, they loaded 8.5.140.0 but were instructed by the controller to load 8.3.143.0.  So this means ALL the APs scrambled to load the other firmware.  And if the WAN link is congested, 75 minutes can be possible.