LDAP : retrieving structure

Hi , I need to ask how to retrieving a LDAP db structure. I've reached this point: making a serach by ONE_LEVEL, and retrievind all objects in the first level using a base DN... after that , how i can see each structure of theese objects in their sub-levels? i've tried with a "ldap_first_entry( ...on the search result... )" and a "ldap_get_attributes" and i get a multidim. array that represents my record-list of each object of my ONE_LEVEL scope....thats right, but now, if I would to see each sub-tructure, witch scope and DN-type i must use into a ldap_search? Someone can giveme an algorithm??? plz, help me. Greetings, Gianluca.