ask for some tips of unified identity using LDAP

["ntyunaka@uol.com.br" <yunakaof@usp.br>]

Hi,

I would like to ask for tips, on how people make a directory system to
make an unique login/password relating all individual information
relating to autorization for each service that an individual could
access.
As service I mean physical access control to a room or building,
e-mail system authentication, dial-up authentication, RADIUS
authentication for other services depends on RADIUS, computer
use access by login in any computer anywhere in a university
campus, administrative system access login, intranet web access
by login, employee entrance control, etc.
This type of directory system exist ?
It can be done using LDAP ?
There is any similar system using OpenLDAP ?

How Universities and big companies do to implement an unique ID
for individuals in fact ?

Sorry for long mail,

Nelson