Authenticating R/3 users using LDAP

Hi,

We are trying to authenticate SAP R/3 users using an already built Microsoft ADS.

We have looked into configuration using trx. LDAP.

But seems like this only helps to synchronize user data between the LDAP and the R/3 system.

We are more looking for the authentication itself being handled by the ADS system.

We do not want to go through the portal for authenticating these users.

Is it possible to do this.?