PPPoE feature - idle timeout

Hi,         

         We are looking for functionality that would disconnect the PPPoE session if the link is idle (no traffic seen from and to ethernet interface for a period of time, so called timeout)  and restore it once activity in the link is detected. It's very useful when WISPs have a large number of clients and ipv4 resource allocation should be very efficient.

Looking forward for a fast implementation,

Andrei