multi user group mapping to radius server

Hello everybody,

i have few user group in the radius server (windows server base) and would like to assign different access permission for those group.

When i configure user group with radius and the group configure "specify", the authentication is not working. If i put any in the group option that is working fine but that is not fulfil the design (assign  different user group with different access permission) May i know is there pre-requisite requirement to configure "specify group?

I did some research that said use "AVP" to mapping radius user group. May i know is that compulsory use "AVP or other way can map the radius user group?

Thanks.