With the introduction of ISE 1.3 and the rewritten guest portal configuration experience, we have the option to send a guest to a specific URL instead of the typical success page. However, it often doesn’t work. The typical wireless guest ACL used with CWA looks something like this:
But, in order to direct the successful guest to a specific URL instead of the typical success page, you need to allow the guest endpoint to reach the PSNs on tcp 8443:
You configure the URL to direct the successful guest attempt from within ISE, and the PSN is the ISE persona that the endpoint actually communicates with. So, you need to allow the guest endpoint to speak with the PSNs via tcp 8443 for this to work properly. In the above screen shot, 172.20.1.34 is the PSN. If you have multiple PSNs, you need to add an entry into the ACL like this for each one.
As of the writing of this blog entry, the details above were not available in any Cisco documentation (that I could find), so I opened a TAC case and asked them to file a document bug for this to be better documented in future versions.
Update: The document bugID for this is CSCux16046.