Need a way to disconnect idle iPads after a certain time period

[spfister336]

We have iPads on our WLAN (5520 WLC with 2802i APs) that stay connected long after they have been used. We tried setting the idle timeout on a test LAN (1800 seconds, 1024000 bytes), but it doesn't seem to work reliably. It will stay connected long after the 30 minutes are up, and when the number of bytes received and sent are far below the threshold specified (2-3k in that half hour). Is this something that's possible?

[balaji.bandi]

you need to troubleshoot the clients why it was not disconnected.

there 2 things you can focus on user idle timeout and session timeout

i would suggest to run debug as mentioned below see the reason :

https://www.borderlessccie.net/?p=220

[Rich R]

Just because the device appears idle (nobody using it) doesn't mean it's idle on the WiFi.  Apps and system processes will be constantly connecting and updating so from WLC point of view the device is not idle.  If you want to disconnect after 30 minutes use that's an absolute session timeout not an idle timeout.  But the device can reconnect again straight after you disconnect it.

So what behaviour are you actually trying to achieve?

[spfister336]

There is some concern here about individual APs that have high numbers of clients associated. Most of our users are students in classrooms of about 30, with an AP in the ceiling of each classroom. The vast majority of classroom APs have no more than 30 to 35 clients maximum, but a handful can have 50 to 60. We have found that in most cases, the issue is a cart full of iPads charging sitting inside the classroom, while the teacher is having the student working on chromebooks. We were hoping the cart full of idle iPads could be timed out in some way so they weren't raising the number of clients on the AP

[Scott Fella]

This is normal and in my past experience in K-12, these carts will stay connected.  You either have to account for density for these devices, but should not really be hogging up any bandwidth, or else you make sure these devices are powered off prior to them going into the charging cart.  What I have also seen, is that these carts will move around to different classrooms, so you will always see higher than usual device counts depending on where these carts are placed.

[Prince.O]

Hello,

As Richard & Scott stated above, because it's idle (not in use) does not indicate it's not sending some traffic to keep it active on the WIFI. Devices tend to go to sleep and wake up from time to time to stay connected. If that is the behavior , the AP/WLC won't disassociate them. 

If the concern is solely the number of clients on the Ap , total of about 50 to 60 and half the devices are not in use and are charging, that won't be a huge issue on the AP . These are considered background devices. The Ap is capable of handling that. The concern arises when you have about 60 active devices being used. Even then , it depends on the application/use case of those devices that will determine if the AP is getting overwhelmed.

[spfister336]

The thing I don't understand is, I've been watching some test iPads and they don't really get to the threshold that's set (currently trying 1Mb of traffic and 30 minutes idle). As a last test, I'm setting the session timeout to 30 minutes as well. I agree it's not really a big issue, but management is requesting this.

[Scott Fella]

You need to share how these devices work with management.  if your idle timer is set to 5 minutes and your session timer is set to 30 minutes as an example, what prevents the iPad from reconnecting?  Nothing, that is what the iPad does, it's always connected in the background.  So power off these devices and that would be your best solution.

[Rich R]

Exactly as Scott says - if management are asking you to do something because they don't understand the technology then you have to explain it to them not just blindly do things that don't serve any useful purpose and could start breaking things!