Browse Prior Art Database

PPP Predictor Compression Protocol (RFC1978)

IP.com Disclosure Number: IPCOM000004196D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2019-Feb-14
Document File: 9 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. Rand: AUTHOR

Related Documents

10.17487/RFC1978: DOI

Abstract

This document describes the use of the Predictor data compression algorithm for compressing PPP encapsulated packets. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 20% of the total text.

Network Working Group D. Rand Request for Comments: 1978 Novell Category: Informational August 1996

PPP Predictor Compression Protocol

Status of This Memo

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

Abstract

The Point-to-Point Protocol (PPP) [1] provides a standard method of encapsulating multiple protocol datagrams over point-to-point links.

The PPP Compression Control Protocol [2] provides a method for transporting multi-protocol datagrams over PPP encapsulated links.

This document describes the use of the Predictor data compression algorithm for compressing PPP encapsulated packets.

Table of Contents

1. Introduction ...................................... 1 2. Licensing ......................................... 2 3. Predictor Packets ................................. 2 3.1 Predictor theory ............................ 2 3.2 Encapsulation for Predictor type 1 .......... 7 3.3 Encapsulation for Predictor type 2 .......... 8 4. Configuration Option Format ....................... 9 SECURITY CONSIDERATIONS .................................. 9 REFERENCES ............................................... 9 ACKNOWLEDGEMENTS ......................................... 9 CHAIR’S ADDRESS .......................................... 9 AUTHOR’S ADDRESS ......................................... 9

1. Introduction

Predictor is a high speed compression algorithm, available without license fees. The compression ratio obtained using predictor is not as good as other compression algorithms, but it remains one of the fastest algorithms available.

Note that although care has been taken to ensure that the following code does not infringe any patents, there is no assurance that it is

Rand Informational [Page 1]

RFC 1978 Predictor Protocol August 1996

not covered by a patent.

2. Licensing

There are no license fees or costs associated with using the Predictor algorithm.

Use the following code at your own risk.

3. Predictor Packets

Before any Predictor packets may be communicated, PPP must reach the Network-Layer Protocol phase, and the Compression Control Protocol must reach the Opened state.

Exactly one Predictor datagram is encapsulated in the PPP Information field, where the PPP Protocol field indicates type hex 00FD (compressed datagram).

The maximum length of the Predictor datagram transmitted over a PPP link is the same as the maximum length of the Information field of a PPP encapsulated packet.

Prior to compression, the uncompressed data begins with the PPP Protocol number. This value MAY be compressed when Protocol-Field- Compression is negotiated.

PPP Link Control Protocol packets MUST NOT be send within compressed data.

3.1. Predictor theory

Predictor works by filling a guess table with values, based on the hash of the previous characters seen. Since we are either emitting the source data, or depending on the guess table, we add a flag bit for ever...

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