WISPr is a draft protocol that enables users to roam between different wireless service providers. Some devices (For example, Apple iOS devices) have a mechanism using which they can determine if the device is connected to Internet, based on an HTTP WISPr request made to a designated URL. This mechanism is used to allow users to launch the web browser if they need to provide credentials to access Internet, and the actual authentication is done in the background every time the device connects to a new SSID.
This HTTP request triggers a webauth interception in the controller as any other page requests are performed by a wireless client. This interception leads to a webauth process, which will be completed normally. If the webauth is being used with any of the controller splash page features (URL provided by a configured RADIUS server), the splash page may never be displayed because the WISPr requests are made at very short intervals, and as soon as one of the queries is able to reach the designated server, any web redirection or splash page display process that is performed in the background is aborted, and the device processes the page request, thus breaking the splash page functionality.
For example, Apple introduced an iOS feature to facilitate network access when captive portals are present. This feature detects the presence of a captive portal by sending a web request on connecting to a wireless network and directs the request to http://www.apple.com/library/test/success.html. If a response is received, then the Internet access is assumed to be available and no further interaction is required. If no response is received, then the Internet access is assumed to be blocked by the captive portal and Apples’s Captive Network Assistant (CNA) auto-launches the pseudo-browser to request portal login in a controlled window. The CNA may break when redirecting to an ISE captive portal. The controller prevents this pseudo-browser from popping up.
You can now configure the controller to bypass WISPr detection process, so the webauth interception is only done when a user requests a webpage leading to splash page load in user context, without the WISPr detection being performed in the background.