I have two controllers running 7.6.MR3. The first controller is primary for all 2702i access points. The second is used for failover.
My question: If the primary controller crashes, how long does it take for the access points that were associated to the primary controller take to failover/accept clients on the secondary/failover controller?
This all depends if you have the WLC's configured for high availability (HA feature). If you do, the APs can failover in sub-seconds. Client re-association is avoided on switchover making the failover seamless for the APs as well as for the clients. This means zero client service downtime.
Take a look at this Cisco document:
Hope this helps!
How is your secondary "failover" controller setup? It can take some time to find your secondary wireless controller if the primary controller goes down. You can improve this time by properly setting up HA/failover. If you were to shut down the switch port on 1 access point and bring it back online, I would say it takes about 3 to 5 minutes or so to discover the controller, bring online its radios and SSIDs. Best thing to do is go to Wireless --> Click on the AP --> click on high availability tab and put in the ip address of the secondary AP. This way, at least the AP knows about the secondary AP IP address. I would also make sure your option43 or DNS entry is properly setup for both controller mgmt. ips.
The point I am trying to make is, depending on how your failover is setup, the time it takes for an AP to failover to another controller can be either not failover properly, take 3-5mins (finding another wireless controller on the network) or seamless (full HA failover)
When you talk about HA you have HA-SSO and regular HA N+1.
Regular HA N+1