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WiSM Switch - Questions about Client Connections


i?m planning a worst case scenario for a customer site. They got a couple of 6500?s with WiSM Modules installed. Now I?m sitting over a instruction of what to do when a WiSM breaks down and I got a few questions regarding the clients.

In the case a Controller stops responding, the AP?s are automatically switched to the secondary Controllers. What happens when the Primary Controller returns - they automatically switch back, right? Is this automatic switch combined with a loss of wireless connectivity? (LWAPP tunnel gets torn down, and a new LWAPP connection must be established - that is basically the same if I restarted the AP, isn?t it? ) If so, how long does it take for the connectivity to return? Is it possible to manually do the switch to a later time (late in the evening..) to minimize the effects for the clients? The Goal is to keep the clients up and running, without termination of the wireless connection - if this is possible.


Re: WiSM Switch - Questions about Client Connections

It is my understanding that once the primary controller comes back online, the lightweight APs will disconnect from the secondary controller, dropping client traffic as they reattach to the primary.

I suppose the easiest way to accomplish what you want is to wait until an after-hours service window before bringing the repaired/replaced primary controller online.



Re: WiSM Switch - Questions about Client Connections

Also, after checking my WLC's Controller->General config screen, you will find a parameter called "AP Fallback".

It can be either "Enabled" or "disabled" and determines whether or not an access point that lost a primary controller connection automatically returns to service when the primary controller becomes functional again.

I suppose that if you set this parameter to "Disabled" in the secondary controller, before activating the repaired/replaced primary controller that this would also accomplish what you want.

It is not clear if the same setting would also need to be applied to the primary controller. You may need to test this aspect first to be sure.

Presumably, you could then re-enable "AP fallback" when you are ready to force the LWAPs back to the primary.

I hope this helps,

- John