HA SKU for two Cisco WLCs

[rbncarvalho]

Hi all,

I'm deploying a High Availability solution for a customer who wants that the secondary WLC assures the two primary WLCs.

The two primary WLCs are at distinct sites, and their management IP Addresses are different, as well as the layer 3 interfaces.

The doubt is how will this scenario will influence the secondary controller configuration?

I've saw at the cisco.com that the SKU WLC has to have the same configuration of the primary, with exception of the management IP, so I don't know and I haven't find the any document that shows the configurations needed for deploy this solution with more than one primary controller.

The solution N+1 is supposed to have more than one primary controller, and rely on one for backup, but I'm having many doubts before move on with this.

Could you guys help me on this?

Thank you,

Best Regards, 

Rúben Carvalho

[Leo Laohoo]

The Redundant Port of the Primary and HA unit must be connected using copper link.  Management IP address must be in the same subnet and the same VLAN.

[rbncarvalho]

So if you have to use the RP port for back to back connectivity, how will you reach the N+1 scenario if you only have one RP per WLC.

Also this solution is supposed to be for a deployment where you have N controllers and one backup.

It assumes that they are not on the same HQ but deployed over branches, so the copper link will not be possible in this scenario.

This is my doubts regarding this scenario. In your answer it assumes only 1:1 redundancy and that's not the purpose of N+1 HA scenario.

If you are able to go further on this subject please post it here, my hands are tied right now.

Thank you for your answer.

[Leo Laohoo]

Also this solution is supposed to be for a deployment where you have N controllers and one backup.

N+1?  How many APs can the HA SKU support?

[rbncarvalho]

Hi Leo,

Please go through this document, http://www.cisco.com/c/en/us/td/docs/wireless/technology/hi_avail/N1_High_Availability_Deployment_Guide/N1_HA_Overview.html

In here you'll find all the details of this solution, as well as regarding the licensing of the HA SKU, but on the document you can read this:

"In the N+1 HA redundancy model, one WLC serves as the backup controller for N primary controllers. When any of the primary WLCs fail, the APs connected to that controller fall back to the backup controller. The AP has to restart its CAPWAP state machine and go through a complete discovery phase before it joins the backup controller. The available AP count on the backup controller is reduced by the number of APs that fall back from the primary WLC to the backup WLC.

For example, when the primary controller supporting 90 APs fails, these APs fall back to the backup controller that has a maximum AP support of 500. The backup WLC is left with an available AP count of 500 - 90 = 410 APs. (See Figure 3-5.)"