[FreeRADIUS and PPPd] How to limit the bandwidth?

Hello there, I'm currently setting up FreeRADIUS as authentication/authorization backend for a PPPoE Server running with the ppp Daemon. I've managed to get the ppp Daemon to work with my working FreeRADIUS 1.0.3 Server but now have to solve another problem. Is it possible to limit the bandwidth the ppp channel allocated via an attribute in FreeRADIUS? Or has someone another Idea how to manage a bandwidth cap? Sincerely, Sebastian Mauer