Access Provisioning and N+1

Question

I have setup 3 new controllers in and N+1 configuration. Two are active and one is an HA-SKU backup controller which either of the primary's can failover to. The setup looks good and has been verified. Now it is time to provision access points. I have about 220 access points which sit in a different VLAN, and believe I need to configure a DHCP option to point towards a controller which brings these questions to mind. (I'd like to break these up between the primary controllers, 110 each)
If I create a DHCP option that forces the AP to register with one controller doesn't this defeat the purpose of N+1?
Or
After the AP botos this will allow me to provision it and then I can specify one of two primary's and the backup controller?
If I specify the primary controller for an AP which is booting via DHCP with an option to point it to the first controller will the AP config override that and allow it to operate on the other primary controller which I just defined?
The controller config was fairly easy, but this is where I got confused.

Answer 1

Hi Matthew,
So this is the setup:
Controller 1 <--> Controller 2 <--> SKU controller
220 APs in different vlans
now you want to laod balance the APs between the two active controllers and keep the SKU as backup for all the APs.
Use DHCP optin 43 to help the APs on each VLAN to learn about that controller
The AP will learn about this WLC and will join it
For other APs in different VLAN let them learn the IP for the other WLC and they will join it.
After the APs joined the correct WLC, you can add the backup controller for them (SKU) from the GUI
If you want each WLC to exculsively allow particular APs to join (and don't accept the other controller APs) you can use AP policy (security -> AAA -> AP policy)
Keep in mind that SKU WLC is just backup and wont allow APs to join if the primary WLC is active hence it wont affect the load balancing
After the AP joins the WLC you can indeed change the primary/ secondary WLC (Wireless -> access point -> select this one -> HA ) or you can do it globally (wireless -> access point -> global configurations -> HA part )
I hope this answered your question!
Cheers,
Nour