Freeradius + PPPOE tun interface

[bishal at baayu.com.np]

I am using PPPOE + Freeradius on Freebsd 6 for adsl connection. Whenever
there is power failure or somebody pull of the network cable at the
client end the user get disconnected from the internet connection.
            and when I checked on pppoe server with ifconfig, I can see
the tun0 interface still hanging on and when the clients connect again
he get connected on the same tun0 interface with the same ip the user
can't browse the net. I tried by kill the tunnel interface but this
doesn't solve my problem.

 Is there any scrips or something that can automatically remove the stale
tunnel interface.