300-425 · Question #216
A customer has multiple WLCs running in N+1 redundancy with APs load balanced between the WLCs. The customer performs AP failover testing between the WLCs and notices that some of the APs do not…
The correct answer is B. APs do not have their secondary WLC information configured correctly. E. APs do not have their primary WLC information configured correctly. When APs fail to return to their primary WLC after recovery, the root cause is misconfigured primary and secondary WLC information on the APs themselves.
Question
A customer has multiple WLCs running in N+1 redundancy with APs load balanced between the WLCs. The customer performs AP failover testing between the WLCs and notices that some of the APs do not move back to their primary WLC after it recovers. What are two points that must be addressed in the design? (Choose two.)
Options
- ADHCP Option 43 information is incorrect.
- BAPs do not have their secondary WLC information configured correctly.
- CAPs failover priorities are set to Low.
- DAP Fallback is not enabled on one of the WLCs.
- EAPs do not have their primary WLC information configured correctly.
How the community answered
(40 responses)- A10% (4)
- B80% (32)
- C8% (3)
- D3% (1)
Why each option
When APs fail to return to their primary WLC after recovery, the root cause is misconfigured primary and secondary WLC information on the APs themselves.
DHCP Option 43 assists with initial AP discovery at boot time and does not govern primary or secondary WLC preferences used during failover and fallback.
If an AP's secondary WLC is configured incorrectly, it may join an unintended WLC during the failover event, placing it in a state where it has no valid path back to its designated primary controller.
AP failover priority (Low/Medium/High) determines the order in which a WLC accepts APs during a failover event, but it does not prevent an AP with correct WLC configuration from returning to its primary.
AP Fallback controls whether APs actively seek to return to their primary WLC after recovery, but the scenario's N+1 load-balanced design points to misconfigured WLC assignments as the more fundamental issue to address.
If the primary WLC name or address is not correctly configured on an AP, the AP cannot identify which controller to return to when that controller comes back online, so it remains wherever it landed during failover.
Concept tested: AP primary and secondary WLC assignment for N+1 failback
Source: https://www.cisco.com/c/en/us/support/docs/wireless/4400-series-wireless-lan-controllers/107606-ApJoinProcess-107606.html
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