One LDAP server, Multiple Domains ( baseDN )

[Saeed Khademi]

Hello,
I am new to this list, and my question maybe asked before.
Sorry if this is a duplicate.

I have one LDAP server, with multiple domain names on it:

LDAP server : A.COM

Domains : A.com
                B.com
                C.com

now I am trying to get it work and authenticate users of all 3 domains correctly. At the same time,
I like to keep the configuration as short & simple as possible.
Tried many scenario’s, the only one that worked was this:
==============
in mods-available/LDAP :

ldap A.com {
.....
}

ldap B.com {
....
}

ldap C.com {
....
}
-----------
in sites-enable/default

authorize {
     pap
     eap
     ....
     A.com
     B.com
     C.com
.....
}


authenticate {
......
    Auth_type ldap {
        A.com
        B.com
        C.com
    }
-----------------
in sites-enabled/inner_tunnel

the same as sites-enable/default

======================================
and it works.
Since all the configuration for all three domains are the same, except for base_DN, what I’d like to have is
to use something like this:
switch ( “&Realm” ) {
      case “A.com”  {  base_dn = {"ou=people,dc=A,dc=com" }
      case “A.com”  {  base_dn = {"ou=people,dc=B,dc=com" }
      case “A.com”  {  base_dn = {"ou=people,dc=C,dc=com" }
}


is it possible to do it? 
if YES, then where should I put it? and what happens for authorize and authentication sections?

Regards,
Saeed.