I've installed a Secondary Ldap Server in another machine and configured it to point at the Master Server with the appropiate password and port.
Although I see the changes I perform on the Primary Server (i.e. modifying a password) on the Secondary Ldap Server by typing: zmprov gaa, I see the "status" of the "ldap2" DOWN in the Administration Console.
There is no firewall or SELinux enabled in both machines.
Here I attach the screenshot.