This documentation is archived and is not being maintained.

Environment for WAN Network Drivers (NDIS 5.1)

Note   NDIS 5. x has been deprecated and is superseded by NDIS 6. x. For new NDIS driver development, see Network Drivers Starting with Windows Vista. For information about porting NDIS 5. x drivers to NDIS 6. x, see Porting NDIS 5.x Drivers to NDIS 6.0.

Windows 2000 and later operating systems support wide area network (WAN) connections over both connectionless and connection-oriented media. The following figure shows the WAN environment.Diagram illustrating the WAN environment for Windows 2000 and later operating systems

The WAN environment includes the following components:

  • Remote Access Service (RAS)

    RAS allows user-mode applications to make dial-up connections. After a RAS connection has been established, a user application can connect to network services through a standard network interface, such as Windows Sockets, NetBIOS, Named Pipes, or RPC.

  • TAPI service provider

    The TAPI service provider is a user-mode component that accepts call setup and tear-down requests from RAS clients and from TAPI-aware applications through the Service Provider Interface (SPI). The TAPI service provider converts such SPI requests to TAPI requests and sends the requests to NDISTAPI if the call is over connectionless media or to TAPI Proxy if the call is over connection-oriented media.


    NDISTAPI is a kernel-mode component that exposes connectionless miniport drivers to the TAPI device space. NDISTAPI accepts call setup and tear-down requests from the TAPI service provider and directs such requests through NDISWAN to the correct miniport driver to set up, monitor, and tear down lines and calls.


    The TAPI proxy is a kernel-mode component that exposes connection-oriented miniport drivers to the TAPI device space. NDPROXY serves as a call manager to NDISWAN and as a connection-oriented client to connection-oriented miniport drivers. For more information about the connection-oriented network environment, see Connection-Oriented Environment for Network Drivers.


    NDISWAN is an intermediate NDIS driver that performs PPP protocol/link framing, compression, and encryption. NDISWAN converts an NDIS_PACKET from an upper-layer transport driver to an NDIS_WAN_PACKET and passes the reformatted packet to an underlying WAN miniport driver. NDISWAN supports both connectionless and connection-oriented miniport drivers.

    When functioning in a connection-oriented environment, NDISWAN acts as a connection-oriented client with respect to the TAPI proxy driver, which presents a call manager interface to NDISWAN.

  • WAN miniport driver

    A WAN miniport driver calls many of the same NDIS functions and supplies many of the same handlers as does a non-WAN NDIS miniport driver. A WAN miniport driver, however, calls special WAN-related NDIS functions when sending packets and when indicating receive packets to overlying protocols. WAN miniport drivers also use an NDIS_WAN_PACKET structure instead of an NDIS_PACKET structure. In addition, WAN miniport drivers maintain WAN-specific information and respond to WAN-specific queries of this information. A WAN miniport driver can support connectionless or connection-oriented media.

  • Serial driver

    The serial driver is a standard device driver for internal serial ports or multiport serial cards. The built-in asynchronous WAN miniport driver for Windows 2000 and later operating systems uses the internal serial driver for modem communications.



Send comments about this topic to Microsoft