< draft-ietf-pppext-pptp-09.txt   draft-ietf-pppext-pptp-10.txt >
Network Working Group K. Hamzeh Network Working Group K. Hamzeh
Internet-Draft Ascend Communications Internet-Draft Ascend Communications
Category: Informational G. S. Pall Category: Informational G. S. Pall
<draft-ietf-pppext-pptp-09.txt> Microsoft Corporation <draft-ietf-pppext-pptp-10.txt> Microsoft Corporation
W. Verthein W. Verthein
3Com 3Com
J. Taarud J. Taarud
Copper Mountain Networks Copper Mountain Networks
W. A. Little W. A. Little
ECI Telematics ECI Telematics
G. Zorn G. Zorn
Microsoft Corporation Microsoft Corporation
April 1999 April 1999
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documents at any time. It is inappropriate to use Internet- Drafts documents at any time. It is inappropriate to use Internet- Drafts
as reference material or to cite them other than as "work in as reference material or to cite them other than as "work in
progress." progress."
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This memo provides information for the Internet community. This This memo provides information for the Internet community. This
memo does not specify an Internet standard of any kind. The memo does not specify an Internet standard of any kind. The
distribution of this memo is unlimited. It is filed as <draft- distribution of this memo is unlimited. It is filed as <draft-
ietf-pppext-pptp-09.txt> and expires October 27, 1999. Please send ietf-pppext-pptp-10.txt> and expires October 30, 1999. Please send
comments to the PPP Extensions Working Group mailing list (ietf- comments to the PPP Extensions Working Group mailing list (ietf-
ppp@merit.edu). ppp@merit.edu).
Abstract Abstract
This document specifies a protocol which allows the Point to Point This document specifies a protocol which allows the Point to Point
Protocol (PPP) to be tunneled through an IP network. PPTP does not Protocol (PPP) to be tunneled through an IP network. PPTP does not
specify any changes to the PPP protocol but rather describes a new specify any changes to the PPP protocol but rather describes a new
vehicle for carrying PPP. A client-server architecture is defined vehicle for carrying PPP. A client-server architecture is defined
in order to decouple functions which exist in current Network in order to decouple functions which exist in current Network
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The words "silently discard", when used in reference to the The words "silently discard", when used in reference to the
behavior of an implementation upon receipt of an incoming packet, behavior of an implementation upon receipt of an incoming packet,
are to be interpreted as follows: the implementation discards the are to be interpreted as follows: the implementation discards the
datagram without further processing, and without indicating an datagram without further processing, and without indicating an
error to the sender. The implementation SHOULD provide the error to the sender. The implementation SHOULD provide the
capability of logging the error, including the contents of the capability of logging the error, including the contents of the
discarded datagram, and SHOULD record the event in a statistics discarded datagram, and SHOULD record the event in a statistics
counter. counter.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1. Protocol Goals and Assumptions . . . . . . . . . . . . . . . . 7 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1. Protocol Goals and Assumptions . . . . . . . . . . . . . . . . 7
1.3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 9 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.1. Control Connection Overview . . . . . . . . . . . . . . . . 9 1.3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 9
1.3.2. Tunnel Protocol Overview . . . . . . . . . . . . . . . . . . 10 1.3.1. Control Connection Overview . . . . . . . . . . . . . . . . 9
1.4. Message Format and Protocol Extensibility . . . . . . . . . . 10 1.3.2. Tunnel Protocol Overview . . . . . . . . . . . . . . . . . . 10
2. Control Connection Protocol Specification . . . . . . . . . . . 12 1.4. Message Format and Protocol Extensibility . . . . . . . . . . 10
2.1. Start-Control-Connection-Request . . . . . . . . . . . . . . . 12 2. Control Connection Protocol Specification . . . . . . . . . . . 12
2.2. Start-Control-Connection-Reply . . . . . . . . . . . . . . . . 14 2.1. Start-Control-Connection-Request . . . . . . . . . . . . . . . 12
2.3. Stop-Control-Connection-Request . . . . . . . . . . . . . . . 17 2.2. Start-Control-Connection-Reply . . . . . . . . . . . . . . . . 14
2.4. Stop-Control-Connection-Reply . . . . . . . . . . . . . . . . 18 2.3. Stop-Control-Connection-Request . . . . . . . . . . . . . . . 17
2.5. Echo-Request . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.4. Stop-Control-Connection-Reply . . . . . . . . . . . . . . . . 18
2.6. Echo-Reply . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.5. Echo-Request . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.7. Outgoing-Call-Request . . . . . . . . . . . . . . . . . . . . 21 2.6. Echo-Reply . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.8. Outgoing-Call-Reply . . . . . . . . . . . . . . . . . . . . . 23 2.7. Outgoing-Call-Request . . . . . . . . . . . . . . . . . . . . 21
2.9. Incoming-Call-Request . . . . . . . . . . . . . . . . . . . . 26 2.8. Outgoing-Call-Reply . . . . . . . . . . . . . . . . . . . . . 23
2.10. Incoming-Call-Reply . . . . . . . . . . . . . . . . . . . . . 28 2.9. Incoming-Call-Request . . . . . . . . . . . . . . . . . . . . 26
2.11. Incoming-Call-Connected . . . . . . . . . . . . . . . . . . . 30 2.10. Incoming-Call-Reply . . . . . . . . . . . . . . . . . . . . . 28
2.12. Call-Clear-Request . . . . . . . . . . . . . . . . . . . . . 32 2.11. Incoming-Call-Connected . . . . . . . . . . . . . . . . . . . 30
2.13. Call-Disconnect-Notify . . . . . . . . . . . . . . . . . . . 32 2.12. Call-Clear-Request . . . . . . . . . . . . . . . . . . . . . 32
2.14. WAN-Error-Notify . . . . . . . . . . . . . . . . . . . . . . 34 2.13. Call-Disconnect-Notify . . . . . . . . . . . . . . . . . . . 32
2.15. Set-Link-Info . . . . . . . . . . . . . . . . . . . . . . . . 36
2.16. General Error Codes . . . . . . . . . . . . . . . . . . . . . 37 2.14. WAN-Error-Notify . . . . . . . . . . . . . . . . . . . . . . 34
2.15. Set-Link-Info . . . . . . . . . . . . . . . . . . . . . . . . 36
3. Control Connection Protocol Operation . . . . . . . . . . . . . 37 2.16. General Error Codes . . . . . . . . . . . . . . . . . . . . . 37
3.1. Control Connection States . . . . . . . . . . . . . . . . . . 38 3. Control Connection Protocol Operation . . . . . . . . . . . . . 37
3.1.1. Control Connection Originator (may be PAC or PNS) . . . . . 38 3.1. Control Connection States . . . . . . . . . . . . . . . . . . 38
3.1.2. Control connection Receiver (may be PAC or PNS) . . . . . . 39 3.1.1. Control Connection Originator (may be PAC or PNS) . . . . . 38
3.1.3. Start Control Connection Initiation Request Collision . . . 40 3.1.2. Control connection Receiver (may be PAC or PNS) . . . . . . 39
3.1.4. Keep Alives and Timers . . . . . . . . . . . . . . . . . . . 41 3.1.3. Start Control Connection Initiation Request Collision . . . 40
3.2. Call States . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.1.4. Keep Alives and Timers . . . . . . . . . . . . . . . . . . . 41
3.2.1. Timing considerations . . . . . . . . . . . . . . . . . . . 41 3.2. Call States . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.2. Call ID Values . . . . . . . . . . . . . . . . . . . . . . . 42 3.2.1. Timing considerations . . . . . . . . . . . . . . . . . . . 41
3.2.3. Incoming Calls . . . . . . . . . . . . . . . . . . . . . . . 42 3.2.2. Call ID Values . . . . . . . . . . . . . . . . . . . . . . . 42
3.2.3.1. PAC Incoming Call States . . . . . . . . . . . . . . . . . 43 3.2.3. Incoming Calls . . . . . . . . . . . . . . . . . . . . . . . 42
3.2.3.2. PNS Incoming Call States . . . . . . . . . . . . . . . . . 44 3.2.3.1. PAC Incoming Call States . . . . . . . . . . . . . . . . . 43
3.2.4. Outgoing Calls . . . . . . . . . . . . . . . . . . . . . . . 45 3.2.3.2. PNS Incoming Call States . . . . . . . . . . . . . . . . . 44
3.2.4.1. PAC Outgoing Call States . . . . . . . . . . . . . . . . . 45 3.2.4. Outgoing Calls . . . . . . . . . . . . . . . . . . . . . . . 45
3.2.4.2. PNS Outgoing Call States . . . . . . . . . . . . . . . . . 46 3.2.4.1. PAC Outgoing Call States . . . . . . . . . . . . . . . . . 45
4. Tunnel Protocol Operation . . . . . . . . . . . . . . . . . . . 47 3.2.4.2. PNS Outgoing Call States . . . . . . . . . . . . . . . . . 46
4.1. Enhanced GRE header . . . . . . . . . . . . . . . . . . . . . 48 4. Tunnel Protocol Operation . . . . . . . . . . . . . . . . . . . 47
4.2. Sliding Window Protocol . . . . . . . . . . . . . . . . . . . 50 4.1. Enhanced GRE header . . . . . . . . . . . . . . . . . . . . . 48
4.2.1. Initial Window Size . . . . . . . . . . . . . . . . . . . . 50 4.2. Sliding Window Protocol . . . . . . . . . . . . . . . . . . . 50
4.2.2. Closing the Window . . . . . . . . . . . . . . . . . . . . . 50 4.2.1. Initial Window Size . . . . . . . . . . . . . . . . . . . . 50
4.2.3. Opening the Window . . . . . . . . . . . . . . . . . . . . . 50 4.2.2. Closing the Window . . . . . . . . . . . . . . . . . . . . . 50
4.2.4. Window Overflow . . . . . . . . . . . . . . . . . . . . . . 51 4.2.3. Opening the Window . . . . . . . . . . . . . . . . . . . . . 50
4.2.5. Multi-packet Acknowledgment . . . . . . . . . . . . . . . . 51
4.3. Out-of-sequence Packets . . . . . . . . . . . . . . . . . . . 51 4.2.4. Window Overflow . . . . . . . . . . . . . . . . . . . . . . 51
4.2.5. Multi-packet Acknowledgment . . . . . . . . . . . . . . . . 51
4.4. Acknowledgment Time-Outs . . . . . . . . . . . . . . . . . . . 52 4.3. Out-of-sequence Packets . . . . . . . . . . . . . . . . . . . 51
4.4.1. Calculating Adaptive Acknowledgment Time-Out . . . . . . . . 53 4.4. Acknowledgment Time-Outs . . . . . . . . . . . . . . . . . . . 52
4.4.2. Congestion Control: Adjusting for Time-Out . . . . . . . . . 54 4.4.1. Calculating Adaptive Acknowledgment Time-Out . . . . . . . . 53
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 55 4.4.2. Congestion Control: Adjusting for Time-Out . . . . . . . . . 54
6. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 55 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 55
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 6. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 55
8. Expiration Date . . . . . . . . . . . . . . . . . . . . . . . . 57 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8. Expiration Date . . . . . . . . . . . . . . . . . . . . . . . . 57
1. Introduction 1. Introduction
PPTP allows existing Network Access Server (NAS) functions to be PPTP allows existing Network Access Server (NAS) functions to be
separated using a client-server architecture. Traditionally, the separated using a client-server architecture. Traditionally, the
following functions are implemented by a NAS: following functions are implemented by a NAS:
1) Physical native interfacing to PSTN or ISDN and control of 1) Physical native interfacing to PSTN or ISDN and control of
external modems or terminal adapters. external modems or terminal adapters.
A NAS may interface directly to a telco analog or digital circuit A NAS may interface directly to a telco analog or digital circuit
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(EAP)", RFC 2284, March 1998 (EAP)", RFC 2284, March 1998
[11] Stevens, R., "TCP/IP Illustrated, Volume 1", p. 300, Addison- [11] Stevens, R., "TCP/IP Illustrated, Volume 1", p. 300, Addison-
Wesley, 1994 Wesley, 1994
[12] Bradner, S., "Key words for use in RFCs to Indicate Requirement [12] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997 Levels", BCP 14, RFC 2119, March 1997
8. Expiration Date 8. Expiration Date
This memo is filed as <draft-ietf-pppext-pptp-09.txt> and expires This memo is filed as <draft-ietf-pppext-pptp-10.txt> and expires
October 27, 1999. October 30, 1999.
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