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Multiple Cisco Controllers Single DNS structure.

We are installing a set of 5508 controllers at one site in Tennessee.

At another divisional site we have another controller that covers that division.

Both sites utilize the same DNS structure and would like to use the DNS entry CISCO-CAPWAP-CONTROLLER

entry for bringing new APs onto the controllers at their sites, how would we go about configuring this?

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Multiple Cisco Controllers Single DNS structure.

This link should help:

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Multiple Cisco Controllers Single DNS structure.

According to this link. If you add the same hostname the AP will resolve all of them and continue with normal join proces like it does with multiple controllers with DHCP option 43. So the comment below is slightly inaccurate according to this. I am doing a test right now I will post the results.

a quote from the link that Scott sent:

When an AP receives an IP address and DNS information from a       DHCP server, it contacts the DNS to resolve       CISCO-LWAPP-CONTROLLER.localdomain. When the DNS sends a list       of controller IP addresses, the AP sends discovery requests to the       controllers.

The AP will attempt to resolve the DNS name       CISCO-LWAPP-CONTROLLER.localdomain. When the AP is able to       resolve this name to one or more IP addresses, the AP sends a unicast LWAPP       Discovery Message to the resolved IP address(es). Each WLC that receives the       LWAPP Discovery Request Message replies with a unicast LWAPP Discovery Response       to the AP.

Multiple Cisco Controllers Single DNS structure.

I just finished my test. I had one DHCP pool with a seperate dns sufix and forward lookup zone on Microsoft DNS.

I created 2 hosts cisco-capwap-controler with different IP addresses. A host reccord.

I pointed 4 capwaps to this DNS. And they load ballanced 2 on each controller. So for me it is proved that the capwap gets knowledge of both controllers and continues normal join process where it joines the least loaded WLC.

It doesn´t show on the AP console what Controller it resloves. Just says (OK) I wonder how that can be seen. Perhaps some debugs on the WLC´s at the same time or to a packet capture on the CAPwap switchport. But I am happy for now.

Multiple Cisco Controllers Single DNS structure.

You can add multiple entries for the same host name in the DNS.

You create two entries for same name for both your controllers. If one is not reachable by the AP then the other one will be tried.

If both WLCs are reachable to the AP then you need to check with microsoft is the retrieved name lookup can be determined based on the source request.




WLC tries two names for name lookup:



If the AP is reachable to only one WLC then one of the solutions would be to configure one name with first WLC ip and the other name with the second WLC ip addresses.

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Multiple Cisco Controllers Single DNS structure.

Do your sites utilize different DNS suffixes? When the AP looks for CISCO-CAPWAP-CONTROLLER it will append whatever DNS suffix was assigned to it during DHCP assignment. So for the main site you could have DHCP return division1.domain which then gets translated as CISCO-CAPWAP-CONTROLLER.division1.domain. The next site would return division2.domain, etc.

Is there a reason why you are using DNS over DHCP? Merely curious, most all sites I've ever worked with have gone the DHCP route, only time looking at DNS was when they were using Infoblox and had issues getting the DHCP options going.

Multiple Cisco Controllers Single DNS structure.

if you are on the console of the AP, you can do show capwap client rcb, or show capwap client config.

this will show you what WLC the AP is joined to as well as which others it knows about.


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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
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