several LDAP servers to authenticate ?

Hello I actually use freeradius to authenticate wi-fi users thru the chillispot software. Our freeradius server use our LDAP as backend and everything runs well now I would like to know if it is possible to use _several_ LDAP servers with freeradius with a kind of the following mechanism : If the login is not found on our local LDAP server it will be search on the next LDAP server in a list and so on until all LDAP servers have been searched ? Thanks a lot -- Regards Frank