Linkage

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

Description

The Linkage subkey stores configuration data for binding network components. The bindings associate devices and services with the transport protocols they use.

Network services, such as Dynamic Host Configuration Protocol (DHCP), and transport protocols, such as TCP/IP, also have Linkage subkeys. Those Linkage subkeys store data about bindings from the perspective of the service. They associate network services and protocols with the devices that support them.

A binding consists of three entries: BindExport and Route . 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 2000, 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.

Change method

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.

Note

A valid binding requires a value for three entries: BindExport and Route .

Tip

To determine the type of hardware device represented by a class-GUID subkey, use a registry editor. 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 globally unique identifier (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.

Related Entries

Linkage subkeys for services