How to differeniate types of users

I have Radius v1.1.7 working great with eDirectory/LDAP, both running on SLES 10 SP3. Right now we use it to control access to our wireless in the district, but its sort an all-or-nothing approach right now. What we are trying to accomplish is to have two SSIDs - one for students and one for staff. As its setup now, anybody can connect to either one. How would I be able to differeniate the two users? I can use attributes and such, but how/where would that be defined? Thanks for your help! -Rob