PPP Dial-Up Sequence

 Last reviewed: March 25, 1997
Article ID: Q124036

The information in this article applies to:
  • Microsoft Windows NT Server versions 3.5 and 4.0
  • Microsoft Windows NT Workstation version 4.0

SUMMARY

This article defines Point-to-Point Protocol (PPP) and discusses its Dial Up sequence implemented with the Windows NT Server version 3.5 Remote Access Service (RAS).

MORE INFORMATION

What is PPP?

The Point-to-Point Protocol is a set of industry standard protocols that enable remote access solutions to interoperate in a multi-vendor network. PPP support in Windows NT version 3.5 ensures that Windows workstations can dial up to remote networks through any industry standard PPP remote access server. It also enables Windows NT Server to receive calls from, and provide network access to other vendors' remote access workstation software. PPP support for TCP/IP, IPX, and NetBEUI makes Windows NT version 3.5 an "Internet-ready" and ideal mobile computing operating system for networks ranging from small workgroups to large enterprises.

PPP Dial-Up Sequence

The dial up sequence for PPP involve the following:

  1. Negotiate Link Control Protocols (LCP). LCP is used to establish and configure link and framing parameters such as maximum frame size. For additional information, refer to the PPP Framing section below.

  2. Negotiate Authentication Protocols. Authentication protocols are used
to 
   determine what level security validation the remote access server can
   perform, and what the server requires. The level of security that can
be 
   negotiated ranges from clear text password authentication to encrypted
   authentication to callback security. For more information on each type
   of authentication protocol, refer to the Authentication Protocols
   section below.

  • Negotiate Network Control Protocols (NCP). NCPs are used to establish and configure different network protocol parameters, such as IP, IPX and 
       NBF. This includes negotiating protocol header compression and
   compression control protocol. For more information on each type of
    NCPs, 
       refer to the Network Control Protocols section below.
    After the above negotiations, the resulting connection remains active until the line is disconnected due to any of the following reasons:
    • User explicitly hangs up the line
    • Line drops due to idle time-out
    • Administrator hangs up the line or
    • An unrecoverable link error occurs

    PPP Framing

    PPP framing defines how data is encapsulated before transmission on the wide area network (WAN). By providing a standard framing format, PPP ensures that various vendors' remote access solutions can communicate and recognize data packets from each other. PPP uses HDLC framing for serial, ISDN and X.25 data transfers.

    Authentication Protocols

    Negotiation of authentication protocols occurs immediately after link quality determination and before network layer negotiation. The two most common types of authentication protocols are as follows:

    • Password Authentication Protocol (PAP) uses clear text passwords and is the least sophisticated authentication protocol. It is typically negotiated if the remote workstation and server cannot negotiate a more secure form of validation. The Windows NT RAS server has an option that prevents clear text passwords from being negotiated. This enables
    system 
       administrators to enforce a high level of security.
  • Challenge-Handshake Authentication Protocol (CHAP) uses a challenge response with a one way encryption on the response.

    Windows NT version 3.5 will always negotiate encrypted authentication when communicating with each other. When connecting to third-party remote access servers or client software, RAS may negotiate clear text authentication if the third-party product does not support encrypted authentication.

    Network Control Protocols

    The three most common types of Network Control protocols are as follows:

    • Internet Protocol Control Protocol (IPCP) is used for configuring, enabling, and disabling IP Protocol modules at both ends of the link.
    • Internet Packet eXchange Control Protocol (IPXCP) is used for configuring, enabling and disabling IPX protocol modules on both ends
    of 
       the Link. IPXCP is widely implemented by PPP vendors. IPX-WAN protocol
   is Novell's alternative to IPXCP. IPX-WAN is not compatible with IPXCP.
   Over time, IPX-WAN and IPXCP may converge to provide one standard for
   IPX network configuration over wide area network. Windows NT 3.5
   provides support for IPXCP which is implemented by the vast majority of
   remote access vendors today. Windows NT 3.5 does not yet support IPX-
   WAN.
  • NetBIOS Frames Control Protocol (NBF CP) is used for configuring, enabling and disabling NetBEUI protocol modules on both ends of the link. NBF CP is a Microsoft proposed protocol for NetBEUI configuration. 
       NBF CP is in "draft" status with the Internet Engineering Task Force
   (IETF).
   \* Include RFC 1717 - MultiLink and a RFC candidate for PPTP. This
   \* applies to NT 4.0
    <Type new or changed text here.> 

       The Microsoft NBF extension for PPP is documented at:

      FTP://FTP.MICROSOFT.COM/DEVELOPR/RFC/NBFCP.TXT.

   This document is a proposed RFC for the NBF control protocol.
    The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

    • Additional query words: prodnt slip
    Keywords : kbnetwork ntras NTSrvWkst
    Version : 3.5 4.0
    Platform : WinNT

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    Last reviewed: March 25, 1997
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