Dear Sir;
i want to discuss one thing,
currently we working in multiple authentication environment where each service like library server,web server,it help desk server and LMS require separate authentication system.
for this purpose we are using active directory and open LDAP.

Now we want to shift it on single sign on environment where user authentication once and he/she can utilize all services.
Sir how it is possible and which authentication service can do it.currently i am studying open source directory structure.