Windows 2000 supports Media Sensing . Media sensing is used under TCP/IP to detect whether your nic is or is not in a link state . A link state is when the physical media inserts itself onto the network. Token Ring and Ethernet network adapters and hubs typically have a link light to indicate the current connection status. Windows 2000 detects link state and whenever it detects a down state, it removes the bound protocols from that adapter until it re-enters up state. When using loopback, you may want to disable state detection using the following Windows 2000 registry hack:

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\Tcpip\Parameters
Name: DisableDHCPMediaSense
Type: REG_DWORD
Value: 0 disabled
Value: 1 enabled

Be careful! Whats disabled? Whats enabled? To disable media sense, set=1.

Note: Media sense is available under TCP/IP only. Not available under ipx or netbuei protocols.

Caution: If you have multiple adapters with multiple routes, this setting would leave a disfunctional link active. Also, if you are a portable user, this feature provides the ability to connect to any network and have everything work, without restarting, release and renewing, and so on.