how to migrate an openldap server to a new linux server

[xpzhang1971]

I have an openldap server I want to clone it to another linux server. However, 
I can't access it by login but can just run ldapsearch because this source 
openldap server only open port 389. 
Now I installed openldap-servers package to target linux server, then what? I 
appreciate if anybody can instruct me or direct me to useful documents.