VPN connection remains active after removing smart card

Hi,

I configured a Microsoft Windows Server 2008 R2 as a remote access server (VPN Server). the only allowed authentication method is "microsoft: Smart Card or other certificate." I deployed an enterprise CA in this machine and everything is working properly.

Now, the problem is that when I remove the smart card from the client while the client is connected to the VPN server, it won't be disconnected. For some security's issues I need the connection get disconnect after removing the authentication certificate (Smart Card), immediately or with expiring a timeout. How can it be done?