The Point-to-Point Protocol (PPP) provides a standard method for transporting multiprotocol datagrams over point-to-point links. PPP does so by establishing and configuring different link and network-layer protocols to carry traffic from point to point. Control and data flow modules make up the PPP control protocols as illustrated in the following figure.
MHMiriam HarlineFigure 4.5 Microsoft PPP control modules
The preceding art shows Password Authentication Protocol (PAP), Challenge Handshake Authentication (CHAP), and Shiva Password Authentication Protocol (SPAP), which perform password authentication of RAS clients. Compression Control Protocol (CCP) is used to negotiate encryption with RAS clients. IPCP, IPXCP, NBFCP, and Other are the Internet Protocol (IP), NetWare IPX, NetBIOS Extended User Interface (NetBEUI), and Other protocol modules, which control RAS client sessions. HDLC stands for the High-level Data Link Control protocol.
PPP running under Windows NT Server supports external and internal ISDN adapters. The key difference for PPP between an external ISDN adapter and an internal ISDN adapter is that the external device sends byte-level PPP (also known as asynchronous PPP). The internal ISDN device, which uses an NDIS and WAN miniport driver, sends bit-level PPP (also known as synchronous PPP).
For compatibility with Windows NT Server, Microsoft recommends that external ISDN devices provide an asynchronous-to-synchronous PPP conversion feature. For information about external ISDN devices that can be used on a computer running Windows NT Server, see the Windows NT Hardware Compatibility List.