Linkage Subkey

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

HKLM\SYSTEM\CurrentControlSet\Control\Class\{Class-GUID}\Device-number (000n)

Description

The Linkage subkey stores configuration data for binding network components. It exists only for net class (adapters) devices that have a class globally unique identifier (GUID) of {4D36E972-E325-11CE-BFC1-08002bE10318}. The bindings associate devices and services with the transport protocols they use.

A binding consists of three entries: UpperBind, Export, and RootDevice. Each of these entries can include more than one component. The entries list the components in a precise order, so the first component in one entry corresponds with the first component in the other entries, and each subsequent component corresponds with subsequent components in the other entries.

In Windows NT 4.0 and earlier, all Linkage subkeys were stored in subkeys of the Services subkey (HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Service-name). In Windows Server 2003, the Linkage subkeys for services are still in the Services subkey, but Linkage subkeys for devices are stored in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\{Class-GUID}, in the numeric subkey representing the particular device.

Notes

  • A valid binding requires a value for three entries: UpperBind, Export, and RootDevice.

  • This information is provided only for reference. Use only published application programming interfaces. Do not include the Linkage subkey in Windows programs. This subkey might not be included in future versions of Windows.

Tip

  • To determine the type of hardware device represented by a class-GUID subkey, use the registry editor Regedit.exe. Click the name of the class-GUID subkey (it appears as a 16-byte alphanumeric string within brackets). The device type appears in the value of the first, unnamed entry in the subkey.

  • Many digits in the GUID are unique to your system. However, the three digits preceding the first hyphen are specific to the device class and are the same on all systems. For example, the three digits preceding the first hyphen in the DVD/CD-ROM drives class are always 965.

Caution

  • Do not change any entries in the Class subkey or any subkey within it. The system configures these subkeys to comply with Plug and Play standards. Changing any data can prevent your computer devices from starting or operating properly.

  • This value is maintained by the Network Configuration subsystem. Do not specify this value in an .inf file.