Radius + SAMBA PDC + LDAP

[Andreas Rudat]

Hi,

I'm using samba as pdc and ldap as user database. That all works fine. 
Now I want to use the ldap database for user auth. for radius.
But when I'm looking here 
http://deployingradius.com/documents/configuration/active_directory.html 
and some other sources, I read everywhere the same. "Konfiguration of 
Kerberos" but why? I think it should also with ntlm only? And does this 
paper is the correct for me? Caus if I understand it correctly in that 
scenario they are using a MS AD?

Thanks
Andreas