According to Microsoft, pre-Beta development milestones of Windows 7 fail to play nice with USB network adapters that rely on pre-Windows Vista drivers. The symptoms involve NDIS 5.x USB network adapters not being displayed in the Windows 7 Performance Monitor. NDIS refers to the Network Driver Interface Specification library, which, following the transition from Windows XP to Windows Vista, evolved to version 6.0. Version 5 of NDIS was used by Windows operating systems before Vista. 

“Perfmon only shows adapters that indicate that they have a physical, hardware connector. Windows Vista and Windows Server 2008 introduced a new Network Driver Interface Specification (NDIS) known as NDIS version 6. Network driver developers are encouraged to move their drivers to this new specification,” Microsoft revealed.

The Redmond company does not have an update to resolve the issue, nor does it indicate that it plans a resolve. With not even a workaround made available for Windows 7, Microsoft is only advising users to make sure that the network adapter comes with drivers updated for NDIS version 6. The Redmond company explained that Windows 7 would be aware of all physical connectors as long as they were plugged in via NDIS miniports built especially for NDIS 6. Only in this context would Perfmon be able to display all physical connectors. Fact is that NDIS in Windows 7 comes with limited support for legacy USB Network Adapters, but only limited.

“While NDIS supports NDIS 5 drivers, it does so in a legacy, compatibility layer and does best-effort to determine if the adapter has a physical connector. If the adapter does not have any hardware resources assigned to it, which is the case for USB NICs, NDIS assumes that the NIC does not have a connector. Perfmon, as a result, will not list the NIC as an available network interface,” Microsoft added.