Oracle Application 11.5.9CU2 upgrade to Oracle application R12.1.3. This upgrade includes upgrade from Portal 3.0.9 , Portal Login server/SSL to Portal 10g/SSO/SSL. Also database upgrade from 220.127.116.11 to 10.2.0.4 patchset. Also I am going to discuss about various paths to upgrade to R12..
The most important aspect of the upgrade to assess you current EBS 11i system techinically and functionally.
Here in the article will be going to cover the technically aspect but will give some guidance on functional aspect.