Microsoft Point-To-Point Compression (MPPC) Protocol
RFC 2118
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RFC - Informational
(March 1997; No errata)
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2013-03-02
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RFC 2118 (Informational)
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Network Working Group G. Pall
Request for Comments: 2118 Microsoft Corporation
Category: Informational March 1997
Microsoft Point-To-Point Compression (MPPC) 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 for
transporting multi-protocol datagrams over point-to-point links.
The PPP Compression Control Protocol [2] provides a method to
negotiate and utilize compression protocols over PPP encapsulated
links.
This document describes the use of the Microsoft Point to Point
Compression protocol (also referred to as MPPC in this document) for
compressing PPP encapsulated packets.
Table of Contents
1. Introduction .......................................... 2
1.1 Licensing ....................................... 2
1.2. Specification of Requirements ................... 2
2. Configuration Option Format ........................... 3
3. MPPC Packets .......................................... 4
3.1 Packet Format.................................... 5
4. Description of Compressor and Encoding .................... 6
4.1 Literal Encoding ................................ 7
4.2 Copy Tuple Encoding ............................. 7
4.2.1 Offset Encoding ............................. 7
4.2.2 Length-of-Match Encoding .................... 7
4.3 Synchronization ................................. 8
SECURITY CONSIDERATIONS ...................................... 8
REFERENCES ................................................... 9
ACKNOWLEDGEMENTS ............................................. 9
CHAIR'S ADDRESS ........................................... 9
AUTHORS' ADDRESS ............................................. 9
Pall Informational [Page 1]
RFC 2118 MPPC Protocol March 1997
1. Introduction
The Microsoft Point to Point Compression scheme is a means of
representing arbitrary Point to Point Protocol (PPP) packets in a
compressed form. The MPPC algorithm is designed to optimize processor
utilization and bandwidth utilization in order to support large
number of simultaneous connections. The MPPC algorithm is also
optimized to work efficiently in typical PPP scenarios
(1500 byte MTU, etc.).
The MPPC algorithm uses an LZ [3] based algorithm with a sliding
window history buffer.
The MPPC algorithm keeps a continous history so that after 8192 bytes
of data has been transmitted compressed there is always 8192 bytes of
history to use for compressing, except when the history is flushed.
1.1. Licensing
MPPC can only be used in products that implement the Point to Point
Protocol AND for the sole purpose of interoperating with other MPPC
and Point to Point Protocol implementations.
Source and object licenses are available on a non-discriminatory
basis from Stac Electronics. Please contact:
Cheryl Poland
Stac Electronics
12636 High Bluff Drive,
San Deigo, CA 92130
Phone: (619)794-4534
Email: cherylp@stac.com
1.2. Specification of Requirements
In this document, several words are used to signify the requirements
of the specification. These words are often capitalized.
MUST This word, or the adjective "required", means that the
definition is an absolute requirement of the specification.
MUST NOT This phrase means that the definition is an absolute
prohibition of the specification.
Pall Informational [Page 2]
RFC 2118 MPPC Protocol March 1997
SHOULD This word, or the adjective "recommended", means that there
may exist valid reasons in particular circumstances to
ignore this item, but the full implications MUST be
understood and carefully weighed before choosing a
different course.
MAY This word, or the adjective "optional", means that this
item is one of an allowed set of alternatives. An
implementation which does not include this option MUST be
prepared to interoperate with another implementation which
does include the option.
2. Configuration Option Format
Description
The CCP Configuration Option negotiates the use of MPPC on the
link. By default or ultimate disagreement, no compression is
used.
A summary of the CCP Configuration Option format is shown below.
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