restart lan connection

hi!
for my first question i really need a solution, an answer to the second would be nice but that's ot really urgent

1) does anyone know how to close and restart a lan connection?

2) how do I detect, for the current lan connection, the "classid of the adapter"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{"ClassID of the Adapter"}

thanks!

How to shutdown and not shutdown the lan adapter??I think it's impossible that using win32 api function.U can find something on the network!..I will find it!..