Limit users traffic quota via radius

[Anonymous <anonymous@netpacket.it>]

Hi,

I'm trying to close the connection of a pre-paid mobile user, after he 
reached a limited amount of traffic (ie. 100 megabytes), the network 
device is a Cisco router.
I've found may way to rate-limit the traffic bandwidth but not one to do 
this.
Is radius the correct way to achieve this goal? It'all about vsa?

Thanks all,


Massimiliano