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Point-to-Point Tunneling Protocol (PPTP)
RFC 2637

Document type: RFC - Informational (July 1999)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 2637 (Informational)
Responsible AD: (None)
Send notices to: No addresses provided

Network Working Group                                          K. Hamzeh
Request for Comments: 2637                         Ascend Communications
Category: Informational                                          G. Pall
                                                   Microsoft Corporation
                                                             W. Verthein
                                                                    3Com
                                                               J. Taarud
                                                Copper Mountain Networks
                                                               W. Little
                                                          ECI Telematics
                                                                 G. Zorn
                                                   Microsoft Corporation
                                                               July 1999

                Point-to-Point Tunneling Protocol (PPTP)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

IESG Note

   The PPTP protocol was developed by a vendor consortium. The
   documentation of PPTP is provided as information to the Internet
   community. The PPP WG is currently defining a Standards Track
   protocol (L2TP) for tunneling PPP across packet-switched networks.

Abstract

   This document specifies a protocol which allows the Point to Point
   Protocol (PPP) to be tunneled through an IP network.  PPTP does not
   specify any changes to the PPP protocol but rather describes a new
   vehicle for carrying PPP.  A client-server architecture is defined in
   order to decouple functions which exist in current Network Access
   Servers (NAS) and support Virtual Private Networks (VPNs).  The PPTP
   Network Server (PNS) is envisioned to run on a general purpose
   operating system while the client, referred to as a PPTP Access
   Concentrator (PAC) operates on a dial access platform.  PPTP
   specifies a call-control and management protocol which allows the
   server to control access for dial-in circuit switched calls
   originating from a PSTN or ISDN or to initiate outbound circuit-

Hamzeh, et al.               Informational                      [Page 1]
RFC 2637        Point-to-Point Tunneling Protocol (PPTP)       July 1999

   switched connections.  PPTP uses an enhanced GRE (Generic Routing
   Encapsulation) mechanism to provide a flow- and congestion-controlled
   encapsulated datagram service for carrying PPP packets.

Specification of Requirements

   In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
   "recommended", "SHOULD", and "SHOULD NOT" are to be interpreted as
   described in [12].

   The words "silently discard", when used in reference to the behavior
   of an implementation upon receipt of an incoming packet, are to be
   interpreted as follows: the implementation discards the datagram
   without further processing, and without indicating an error to the
   sender.  The implementation SHOULD provide the capability of logging
   the error, including the contents of the discarded datagram, and
   SHOULD record the event in a statistics counter.

Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   1.1.  Protocol Goals and Assumptions . . . . . . . . . . . . . .   4
   1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .   5
   1.3.  Protocol Overview  . . . . . . . . . . . . . . . . . . . .   6
   1.3.1.  Control Connection Overview  . . . . . . . . . . . . . .   7
   1.3.2.  Tunnel Protocol Overview . . . . . . . . . . . . . . . .   7
   1.4.  Message Format and Protocol Extensibility  . . . . . . . .   8
   2.  Control Connection Protocol Specification  . . . . . . . . .  10
   2.1.  Start-Control-Connection-Request . . . . . . . . . . . . .  10
   2.2.  Start-Control-Connection-Reply . . . . . . . . . . . . . .  12
   2.3.  Stop-Control-Connection-Request  . . . . . . . . . . . . .  15
   2.4.  Stop-Control-Connection-Reply  . . . . . . . . . . . . . .  16
   2.5.  Echo-Request . . . . . . . . . . . . . . . . . . . . . . .  17
   2.6.  Echo-Reply . . . . . . . . . . . . . . . . . . . . . . . .  18
   2.7.  Outgoing-Call-Request  . . . . . . . . . . . . . . . . . .  19
   2.8.  Outgoing-Call-Reply  . . . . . . . . . . . . . . . . . . .  22
   2.9.  Incoming-Call-Request  . . . . . . . . . . . . . . . . . .  25
   2.10.  Incoming-Call-Reply . . . . . . . . . . . . . . . . . . .  28
   2.11.  Incoming-Call-Connected . . . . . . . . . . . . . . . . .  29

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