Replication of a LDAP Server

Hello all,
I work for a school and here's my case :

I need to synchronise my clearos main LDAP server to different slaves at different locations and configurations.

Here's the situation :

At the head office of the school, I'm not responsible for the network infrastructure. I just have the management of a specific vlan (without the management of a firewall). Inside this vlan, I've a Cleaors acting as a dhcp and ldap server to authenticate MAC computers. Everynight, my ldap is synchronized with an export of a udge AD system from my government . So, this first ClearOS is my master. Inside that VLAN, I'd lo install a second system in case of failure.


I'm not allowed to do any incoming communication from the internet in this vlan. However, I do have a DMZ available. So I would like to install a second server in my DMZ for replication. In my DMZ, I'll have other servers (like Moodle) wich are going to connect to my LDAP for the authentication ; so they'll have to authenticate to the one installed in my DMZ.

Finally, I've a part of the school in another city. There, I've a clearos system acting as a gateway and I've the full control of the infrastructure. I'd like that the ldap of this system is the slave of the one in my DMZ (students and teachers are the same).

So, is it possible to install 4 clearOS system (2 in my main vlan), 1 in my DMZ and 1 (existing) in the other city and configure them in the way : vlan --> DMZ ---> other city ?

of, for the one in the dmz, can I just install a basic centos server with openldap and than make the same synchronisation : VLAN (Clearos) --> DMZ (basic centos) --> Other city (ClearOS)

Per advance, thanks for your help
Arnaud