Media Access Control Layer

Because the NDIS interface handles raw packets, the protocol stack is normally responsible for building each frame, including Media Access Control (MAC) layer headers. This means that the protocol stack must explicitly support each media type. Microsoft 32-bit TCP/IP for Windows NT versions 4.0 and 3.5x provides support for:

• Ethernet (and 802.3 SNAP)
• FDDI
• Token Ring (802.5)
• ARCNET
• WAN (switched virtual circuit wide area media, such as ISDN, X.25, and dial-up or dedicated asynchronous lines)

In addition, there are now asynchronous transfer mode (ATM) adapters available for Windows NT. The drivers for these adapters use "LAN emulation" to appear to the protocol stack as a supported media type, such as Ethernet.