Cisco Wireless question about client disassociation

[subevenis]

So something I've been noticing a lot when attempting to troubleshoot clients through Prime Infrastructure... a lot of wireless clients seem to disassociate fairly frequently and then immediate associate again... usually to a different AP. The association history in Prime for the client ends up looking like a repeating wave between three APs. The durations between association times usually seem to always be around an a factor of 5 minutes... so 15 min 14 sec, 10 min 14 sec, 25 min 39 sec, 1 hr 10 min 55 sec, etc.

I've been wondering what this is about and how it probably affects the end-user experience. My assumption is it is disruptive due to the client having to move between APs... so anything real-time and/or latency sensitive like video chat or online gaming might be affected. I figured at first it may be due to a system default of 5 minutes on the User Session Idle but I adjusted it up to an hour and didn't see a noticeable difference. DCA is currently set on an interval of 10 minutes and I have EDRRM on so it seems like it wouldn't always happen in a factor of 5 between changes.

I can see a ton of RRM events for 2.4ghz, so many so that Prime is saying there are to many unique events per device, so I think I may need to tweak 2.4ghz RRM sensitivity down but the clients I'm seeing are also 5ghz which doesn't have nearly as much of an interference or co-channel utilization issue at our location and no where near the number of events.

Anyone have any thoughts or experience with this or is this just normal?

[MHM Cisco World]

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/116493-technote-technology-00.html

This doc. For why there is associate and disassociate.

[Flavio Miranda]

Hi

 The roaming is an expected behavior but with some space between roaming. In your case, seems to me not normal. Although I´ve seen worst.

 The roaming should not cause service interruption IF clients dont need to re-authenticate. If the PMK (Pair Wise Master Key) is present on the Access Point candidate, clients can smootly roaming between AP pretty fast and maybe client loose one ping on this process. Considering 802.1X.

 The problem is related to the client, always. But, for sure,the network can help. Changing  RRM interval is not recommended. 

I´d start with checking client roaming sensibility and set it to lower sensibility if that the case.  Keep client driver uptade and use good wireless adpter.

  The problem is that client will prefer higher RSSI dont matter what. This is odd because higher RSSI does not means that the AP has better condition. So, it is important to have an balanced environment in terms of AP distribuition.  The WLC will work better when the environment allows it with enough AP and no obstacle between then.

[Arshad Safrulla]

First I would start by increasing the DCA timer to somewhere north of 4 hours. Without proper understanding or logs, we will not be able to tell you what caused the disconnection. So if you want to know the reason what caused the disconnections please post a radio active trace from an offending client.

As you correctly said looking at configured timeout values, session timeout must be set to the maximum possible value in your WLC (in 9800 do not set this to 0, recommendation is 86400, In older AireOS you can set unlimited or 65535). Session Timeout will make sure that the Wireless client is deauthenticated after the set timer even it is actively transmitting and receiving data.

Idle Timeout is there to make sure that the wireless client is deauthenitcated after client is idle for certain time, where the time is defined in the WLC. Set this to somewhere around 30 mins to 1 hour.

Also most importantly make sure that the clients are running the latest wlan driver.