If you are planning to install oracle Forms, Reports, Portal and Discoverer 11g, few core components including Oracle Internet Directory (OID), Oracle Single Sign-On (OSSO) with Delegated Administration services and Oracle Weblogic server must be installed and configured before running installer for oracle Forms, Reports, Portal and Discoverer 11g. You can skip these except Weblogic server if you have decided to install only Forms and Reports and you do not require Sign Sign-on in Reports and Forms.
In case of OID, you can install either Oracle Internet Directory 11g or Oracle Internet Directory 10g (10.1.4.3.0). Until now, Oracle Fusion Middleware has no Single sign-on, so you must install single Sign-on version 10g (10.1.4.0) with Delegated Administration services.
If you want to use OID 11g you can install it with Oracle Database 11g (126.96.36.199.0) or Oracle Database 10g (10.2.0.4). For OID 10g you should use Oracle Database 10g (10.2.0.4). Although OID 10g(10.1.4.3.0) can be installed on 10.1.0.5 or higher version but Portal 11g and Discover 11g repositories support only Oracle Database 10g (10.2.0.4) or oracle Database 11g (188.8.131.52.0) or higher.
Weblogic server is required for Oracle Internet Directory 11g and for Forms, Reports, Portal and Discoverer 11g.
If you have decided to proceed with Oracle Internet Directory 11g, visit following links to view step by step installation guide,
If you have decided to proceed with Oracle Internet Directory 10g, visit following link