How to get user Group from LDAP server


We are using LDAP to authenticate users for our application. After migrate to IS 6.5, the LDAP information is no longer stored in the IS server. And now, after moving the IS server to version 6.5, we can get the user authenticated via the configured LDAP server. However, we could not get the user groups information from the LDAP. We can get the user object from the current InvokeState object. The problem is there is no membership information associated with the user object.

Is there a way to get the user group information from the default (configured) LDAP server on the IS? Or we have to set up another LDAP connection in a service to query the groups data for a user?

Any help will be appreciated. Thanks,