The scenario is as follows:
Initially the customer had a single 7510 Flex WLC deployed servicing 605 APs at 60 sites. A second 7510 Flex WLC was purchased direct from Cisco, but it was an HA (no AP license) version. When the customer discovered they could not do AP SSO across two geographically separate locations, they proceeded to deploy the new WLC at their DR site, with the assurance that even without AP licenses, the HA WLC would accept AP registrations as a backup WLC for up to 90 days.
Configured the primary WLC with the Global Configuration defining the new WLC as the Primary Backup WLC. Placed both WLCs into the same Mobility Group. Tested the failover by blocking traffic to the primary WLC, and the APs at one location failed over to the new WLC as expected.
However, they do not fail back to the Primary WLC when it comes back online.
Nothing was defined in the Primary, Secondary, and Tertiary fields on the individual APs, so as a test I defined the Primary and Secondary WLCs. Rebooting that AP, it rejoined the Secondary WLC, even though the Primary WLC is available and reachable (5246 isn’t blocked, etc.) –it had just been joined to it previously. I thought this may be a case of the AP choosing the least-loaded WLC in the Mobility Group, so I removed/decoupled the mobility group, placing the DR WLC in its own Mob. Group. Rebooting the AP again yielded the same results.
For some reason it is discounting the Primary WLC completely even though it knows it’s the WLC of choice through Option 43 on DHCP, and by defining it specifically as Primary under the AP’s High Availability tab.
I had the onsite resource do a “Clear Config” then reboot of an AP to see if the behavior corrects itself, and capture the console output of the AP during the reboot. This appears to have fixed the immediate issue, but doesn’t answer why.
Any suggestions or comments are welcome.
Thanks in advance.