Wireless Access

Occasional Contributor II

Question on Controller discovery and Redundancy


I'm looking for some clarity around design in a 2 controller setup with multiple AP groups maping to different buildings on site, and a requirement to have both controllers active.

  1. How are AP's load balanced across the 2 controllers? I believe this is through the LMS IP and Backp-LMS IP. Is this accurate?
  2. Reading the guides, i'm a little confused on how Controller Redundancy, AP availability/redundancy, AP load balancing across controllers and Controller discovery work together. To further explain: 
  3. For controller availability, If I enable VRRP and use the virtual IP as the LMS IP, how can I use the Backup-LMS IP and the LMS IP settings to distrubute AP groups across controllers for load balancing? Assuming load balancing of AP's is configured using the Backup-LMS IP and LMS IP?
  4. For Controller discovery, If I had a master local setup, and the master was down can the AP boot via the local controller? If yes, what IP would I map the aruba-master dns entry to? Both controller IP's? Is it supported to dish both local and master IP's via the aruba-master dns querry? I guess if using VRRP i'd set the dns entry aruba-master to the VRRP virtual IP?
  5. I would like to use the High Availability feature instead of the LMS-IP for AP availability. Can i still use VRRP for controller availability, High Availability for AP availability and how can i also load balance AP's across controllers since using VRRP uses the virtual IP as opposed to the LMS-IP and Backup-LMS IP?

I hope this makes sense, feels like i spoke in circles.


Thanks all for your time/expertise.



MVP Expert

Re: Question on Controller discovery and Redundancy



I will try to summarize the answers in the below points:


1. Yes, AP can be redirected to different controllers based upon the LMS settings.


2. As you need both the controllers to be active, you would configure them in master-local topology.


As you are interested in using HA, the LMS IP can't be the VRRP IP.


However, VRRP IP can be used for controller discovery. basically, you can point the DNS entry for aruba-master to VRRP IP address.


Eg: - Master Local VRRP IP  (create DNS entry for aruba-master pointing to this address).


In case you do not plan to use VRRP, you can map IP's of both master/local controller to aruba-master. The response for aruba-master will contain both the IP's. AP will try to reach the first IP in the response. If it is unable to communicate with the 1st IP, it will then try to contact the 2nd IP.


Basically, your HA profile will have both the controllers set in dual role as shown in following example:


ha group-profile "HA"
controller role dual
controller role dual


You will need couple of AP system profiles:


AP System profile 1: Will be used in the AP-group where AP's need to use master controller as primary controller.





AP system profile 2: Will be used in the AP-group where AP's need to use local controller as primary controller.





Then you can make both the controllers member of this HA profile. You can also enable state-snchronization in the HA profile (explanation provided in the user guide).


Note: The above configuration will allow the AP's to make use of HA failover mechanism.


Please refer to UG for more details information.

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