WLC Discovery Issue - AP's connecting to wrong WLC when primary WLC becomes unavailable...

[NoProblemAtoll]

I am setup up a mesh wireless network with a Cisco 5508 Wireless Lan Controller (WLC) and (5)x Cisco 2602 AP's.  I having an issue with WLC Discovery that has me a bit stumped.  The WLC Discovery is working and the Cisco 2602's are finding, connecting to, and downloading the config from my Cisco 5508 WLC; however when I have had a something happen where my Cisco 5508 WLC went offline (lost connectivity or lost power) my AP's are connecting to an external WLC at my ISP and loading the ISP's AP config.  How do I go about preventing this from happening?  

[Ric Beeching]

Are these 2602s new or have they been previously joined to the ISP WLC? The APs use a number of discovery mechanisms to find WLCs such as DHCP, DNS and L2 broadcast (same subnet), but will also store their known joined WLC information. Additionally, if your WLC is in the same mobility group as the ISP one then the APs will be informed of that WLCs existence. When those APs lose connectivity to your 5508 they are running through those discovery mechanisms to join the ISP WLC so you need to remove that possibility. Can you simulate the experience and paste the output of an AP from its console port when the 5508 goes down?

Assuming that your DNS or DHCP servers aren't responding to AP discovery requests and pointing them to your ISP WLC, and the ISP WLC is not in the same subnet as those APs, you should be able to default the AP config and setup from fresh without anything in their DB falling back to the ISP WLC.

Ric