Open Stack

Hi there..!!

I am new in openstack. We are planning to implement Openstack Nova and 
Swift too.  So we are in designing and planning stage. So i am in need 
of help for Ldap issue.
As i understand LDAP is required for Openstack compute. So i want to 
know, is LDAP inbuilt/integrated with Compute package..?
If not then what is recommended LDAP to be used for openstack 
compute...like OpenLDAP, OpenDS, Apache Directory etc.....?

Thanks,
Sonali Jadhav