NdisIfAllocateNetLuidIndex function

The NdisIfAllocateNetLuidIndex function allocates a NET_LUID index for an NDIS network interface provider.


NDIS_STATUS NdisIfAllocateNetLuidIndex(
  NET_IFTYPE ifType,
  PUINT32    pNetLuidIndex



The Internet Assigned Numbers Authority (IANA) interface type for an index. For example, IF_TYPE_ETHERNET_CSMACD (6) is the value for IfType that is assigned to any Ethernet-like interface. For a list of interface types, see NDIS Interface Types.


A pointer to a caller-supplied NET_LUID index variable. If allocation is successful, NdisIfAllocateNetLuidIndex sets this variable to the allocated 24-bit NET_LUID index value.

Return Value

NdisIfAllocateNetLuidIndex returns one of the following values:

Return code Description
The operation completed successfully.
The operation failed because of insufficient resources.


NDIS interface providers call the NdisIfAllocateNetLuidIndex function to allocate a NET_LUID index. An interface provider must allocate a NET_LUID index before the interface provider can register an interface.

NdisIfAllocateNetLuidIndex attempts to allocate a 24-bit NET_LUID index that is unique to the local computer and is associated with the interface type that the IfType parameter specifies. NDIS records the NET_LUID index in persistent storage so that the index can remain associated with the same interface even after the computer restarts. NDIS will not allocate the same NET_LUID index to future callers of NdisIfAllocateNetLuidIndex until after the interface provider calls the NdisIfFreeNetLuidIndex function to free the index.

To build a NET_LUID value from the NET_LUID index and the interface type, an interface provider calls the NDIS_MAKE_NET_LUID macro.

The interface provider must store the NET_LUID values that it allocates in persistent storage. For example, if there is a loss of computer power, the provider should have stored the NET_LUID values in persistent storage so it can call NdisIfFreeNetLuidIndex later to free any indexes that are no longer in use. Also, the provider should use the same NET_LUID value whenever it registers the same interface with the NdisIfRegisterInterface function.


Minimum supported client Supported in NDIS 6.0 and later.
Target Platform Desktop
Header ndis.h (include Ndis.h)
Library Ndis.lib
DDI compliance rules Irql_Interfaces_Function

See Also