traffic limiting & QoS attributes (noob RADIUS question)

I'm looking up how RADIUS can limit / throttle various traffic, and I'm wondering what attributes there are that do this. The application would be for an ISP that wants to throttle users who attach to a certain access point. People who attach would then authenticate to RADIUS and then get assigned a certain profile (say, "best effort" and "premium"). I'm new to RADIUS, and I'm hoping to see what types of QoS is available at the RADIUS level so that I can see what other QoS stuff we might need to put in place. thx in advance! Rogelio