Wireless Access

We have noticed that if an iDevice goes to sleep and when the user wakes it up. It redisplays the Captive Portal login screen. I have the DHCP time out at 4 hours. The iPhone and iPad after being asleep for about 45 minutes, when woken up goes to the Captive Portal page. We have only noticed this on iDevices Any ideas why?

This is not unique to iDevices; but rather they often go to sleep so it is more noticeable.   The timeout you are seeing is not DHCP related, but rather the timeout of the user in the active user table.    

The setting is under Configuration --> Authentication --> Advanced --> User Idle Timeout (default is 300 seconds).

When this idle threshold is reached, the controller will send a probe request to see if the device is still there.   If it is, the timer is reset.  If it is not (ie. iPas asleep) then the user is dropped from the user table.  Extending this too long however will keep disconnected users in the table for that time period as well.

If you have ClearPass you can manipulate this by pairing a guest with their mac address; and then doing mac authentication on the guest network; so when the iPad comes back online, it will pass mac authentication, rather than go to the Captive Portal page.

Thanks. I tried to extend the time but the highest it will let is 300 seconds.

Do it from the CLI.   If I remember correclty, if you try from the WebUI, it complains about one of the other settings on the page, which prevents you from saving it.

aaa timers idle-timeout XXXX seconds

We use a value of 25 min. Seems high but when you're dealing with hotspots in coffee shops. When a user connects, goes to get coffee then comes back sometimes its more than 5, 10 or 15 min..

:)