I have configured open ladp on Ubuntu 14.04 sever with phpldapadmin, i want to configure a secondary ldap so that if the primary goes down then no user will affect and secondary will start work with the same . And i want to sonfigure the auto sync so if i made any changes on primary ldap or add any user that will automaticaly sync with secondary ldap. How to do the replication over two ldaps

Please help me to configure this .

Thank You in advance