PPP LCP Extensions
RFC 1570
Document | Type |
RFC - Proposed Standard
(January 1994; No errata)
Updated by RFC 2484
Updates RFC 1548
|
|
---|---|---|---|
Author | William Simpson | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 1570 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group W. Simpson, Editor Request for Comments: 1570 Daydreamer Updates: 1548 January 1994 Category: Standards Track PPP LCP Extensions Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract The Point-to-Point Protocol (PPP) [1] provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP defines an extensible Link Control Protocol (LCP) for establishing, configuring, and testing the data-link connection. This document defines several additional LCP features which have been suggested over the past few years. This document is the product of the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the ietf-ppp@ucdavis.edu mailing list. Table of Contents 1. Additional LCP Packets ................................ 1 1.1 Identification .................................. 1 1.2 Time-Remaining .................................. 3 2. Additional LCP Configuration Options .................. 6 2.1 FCS-Alternatives ................................ 6 2.1.1 LCP considerations .............................. 7 2.1.2 Null FCS ........................................ 8 2.2 Self-Describing-Padding ......................... 9 2.3 Callback ........................................ 11 2.4 Compound-Frames ................................. 12 2.4.1 LCP considerations .............................. 14 APPENDICES ................................................... 15 A. Fast Frame Check Sequence (FCS) Implementation ........ 15 A.1 32-bit FCS Computation Method ................... 15 SECURITY CONSIDERATIONS ...................................... 17 REFERENCES ................................................... 17 ACKNOWLEDGEMENTS ............................................. 18 CHAIR'S ADDRESS .............................................. 18 EDITOR'S ADDRESS ............................................. 18 Simpson [Page i] RFC 1570 PPP LCP extensions January 1994 1. Additional LCP Packets The Packet format and basic facilities are already defined for LCP [1]. Up-to-date values of the LCP Code field are specified in the most recent "Assigned Numbers" RFC [2]. This specification concerns the following values: 12 Identification 13 Time-Remaining 1.1. Identification Description This Code provides a method for an implementation to identify itself to its peer. This Code might be used for many diverse purposes, such as link troubleshooting, license enforcement, etc. Identification is a Link Maintenance packet. Identification packets MAY be sent at any time, including before LCP has reached the Opened state. The sender transmits a LCP packet with the Code field set to 12 (Identification), the Identifier field set, the local Magic-Number (if any) inserted, and the Message field filled with any desired data, but not exceeding the default MRU minus eight. Receipt of an Identification packet causes the RXR or RUC event. There is no response to the Identification packet. Receipt of a Code-Reject for the Identification packet SHOULD generate the RXJ+ (permitted) event. Rationale: This feature is defined as part of LCP, rather than as a separate PPP Protocol, in order that its benefits may be available during the earliest possible stage of the Link Establishment phase. It allows an operator to learn the identification of the peer even when negotiation is not converging. Non-LCP packets cannot be sent during the Link Establishment phase. Simpson [Page 1] RFC 1570 PPP LCP extensions January 1994 This feature is defined as a separate LCP Code, rather than a Configuration-Option, so that the peer need not include it with other items in configuration packet exchanges, and handle "corrected" values or "rejection", since its generation is both rare and in one direction. It is recommended thatShow full document text