help regarding PPPOE Server

[Tears !]

Dear Members!

  I have configured PPPoE server with FreeRadius on my FreeBSD 6.2 machine
and client side i am using RASPPPOE on windows machine. Its working fine but
a issue has been occurred.

Some time if my client shutdown there PC without properly disconnecting
pppoe session then my PPPOE server didn't  close the session.

---------------------------------------------
tun1: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
        inet 192.168.1.1 --> 192.168.1.196 netmask 0xffffffff
        Opened by PID 1024
tun2: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
        inet 192.168.1.1 --> 192.168.1.227 netmask 0xffffffff
        Opened by PID 1100
tun3: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
        inet 192.168.1.1 --> 192.168.1.27 netmask 0xffffffff
        Opened by PID 1180
tun4: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
        inet 192.168.1.1 --> 192.168.1.59 netmask 0xffffffff
        Opened by PID 1204

--------------------------------------------

Then i manually killed the PID of (tun1, tun2, tun3 , tun4) because if my
any client trying connect my PPPOE server they will get tun5 with new IP. so
previous 4 session will be there until i manually kill that.

So please help me what should i do ?

Regards,

-----
Umar Draz