Problem
AP not getting associated while moving from one WLC to another WLC in mobility group.
Resolution
This problem occurs if the AP moves between WLCs that are running different WLC software versions. Ensure that WLCs are running the same version to solve the problem.
Also it is recommended, that High Availability (HA) is configured on all the APs, in order to decrease the time that it takes to move to a another controller and for wireless service to resume after a controller associated with another WLC.
FAQ
Q. Now another challenge is , i cannot upgrade the licenses from 5508-250 to 5508-500 , as minimum ios recommended is 7.0. ?
A. Yes.
http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn7.0.html#wp626190
Q. Is there any way, I can do to upload the license, without having downtime of wireless network?
A. It depends on the 7.0 code that you're running. if you're on 7.2.103.0 then you can apply adder licenses without rebooting the controller.
http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn7_2.html#wp855325
More Information
High Availability Enhancements in Wireless LAN Controller Software Release 5.0
In wireless network deployments that run controller versions earlier than 5.0, when a controller goes down, it takes a long time for all the APs and the associated clients to move to a backup controller and for wireless service to resume.
The features discussed in the document are implemented on the controller CLI in WLC software release 5.0 in order to decrease the time that it takes for access points and their associated clients to move to a backup controller and for wireless service to resume after a controller goes down:
- In order to reduce the controller failure detection time, you can configure the heartbeat interval between the controller and access point with a smaller timeout value.
- In addition to the option to configure primary, secondary, and tertiary controllers for a specific access point, you can now also configure primary and secondary backup controllers for a specific controller. If the local controller of the access point fails, it chooses an available controller from the backup controller list in this order:
- primary
- secondary
- tertiary
- primary backup
- secondary backup
- The access point maintains a list of backup controllers and periodically sends primary discovery requests to each entry on the list. You can now configure a primary discovery request timer in order to specify the amount of time that a controller has to respond to the discovery request of the access point before the access point assumes that the controller cannot be joined and waits for a discovery response from the next controller in the list.
Mobility group will only let the joined APs learn the WLC IPs on that mobility domain, for WLC selection you need to have HA configured on all the APs, without that configured APs will try to join least loaded wlc/master/backup wlcs that learnt through different mechanism however test capwap controller ip should let join the specific wlc.
Reference
High Availability Enhancements in Wireless LAN Controller
Source:cannot see access points when switched from one controller to another controller
