RFC 2637 (rfc2637) - Page 2 of 57
Point-to-Point Tunneling Protocol
Alternative Format: Original Text Document
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 2.12. Call-Clear-Request . . . . . . . . . . . . . . . . . . . 31 2.13. Call-Disconnect-Notify . . . . . . . . . . . . . . . . . 32 2.14. WAN-Error-Notify . . . . . . . . . . . . . . . . . . . . 33 2.15. Set-Link-Info . . . . . . . . . . . . . . . . . . . . . . 35 2.16. General Error Codes . . . . . . . . . . . . . . . . . . . 36 3. Control Connection Protocol Operation . . . . . . . . . . . 36 3.1. Control Connection States . . . . . . . . . . . . . . . . 37 3.1.1. Control Connection Originator (may be PAC or PNS) . . . 37 3.1.2. Control connection Receiver (may be PAC or PNS) . . . . 39 Hamzeh, et al. Informational



