The PPP Compression Control Protocol (CCP)
RFC 1962

Network Working Group                                            D. Rand
Request for Comments: 1962                                        Novell
Category: Standards Track                                      June 1996

               The PPP Compression Control Protocol (CCP)

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
   also defines an extensible Link Control Protocol.

   This document defines a method for negotiating data compression over
   PPP links.

Table of Contents

   1.     Introduction ..........................................    1
   2.     Compression Control Protocol (CCP) ....................    2
      2.1       Sending Compressed Datagrams ....................    3
   3.     Additional Packets ....................................    4
      3.1       Reset-Request and Reset-Ack .....................    4
   4.     CCP Configuration Options .............................    5
      4.1       Proprietary Compression OUI .....................    7
      4.2       Other Compression Types .........................    8
   SECURITY CONSIDERATIONS ......................................    9
   REFERENCES ...................................................    9
   ACKNOWLEDGEMENTS .............................................    9
   CHAIR'S ADDRESS ..............................................    9
   AUTHOR'S ADDRESS .............................................    9

1.  Introduction

   In order to establish communications over a PPP link, each end of the
   link must first send LCP packets to configure and test the data link
   during Link Establishment phase.  After the link has been
   established, optional facilities may be negotiated as needed.

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RFC 1962                    PPP Compression                    June 1996

   One such facility is data compression.  A wide variety of compression
   methods may be negotiated, although typically only one method is used
   in each direction of the link.

   A different compression algorithm may be negotiated in each
   direction, for speed, cost, memory or other considerations, or only
   one direction may be compressed.

2.  Compression Control Protocol (CCP)

   The Compression Control Protocol (CCP) is responsible for
   configuring, enabling, and disabling data compression algorithms on
   both ends of the point-to-point link.  It is also used to signal a
   failure of the compression/decompression mechanism in a reliable
   manner.

   CCP uses the same packet exchange mechanism as the Link Control
   Protocol (LCP).  CCP packets may not be exchanged until PPP has
   reached the Network-Layer Protocol phase.  CCP packets received
   before this phase is reached should be silently discarded.

   The Compression Control Protocol is exactly the same as the Link
   Control Protocol [1] with the following exceptions:

   Frame Modifications

      The packet may utilize any modifications to the basic frame format
      which have been negotiated during the Link Establishment phase.

   Data Link Layer Protocol Field

      Exactly one CCP packet is encapsulated in the PPP Information
      field, where the PPP Protocol field indicates type hex 80FD
      (Compression Control Protocol).

      When individual link data compression is used in a multiple link
      connection to a single destination, the PPP Protocol field
      indicates type hex 80FB (Individual link Compression Control
      Protocol).

   Code field

      In addition to Codes 1 through 7 (Configure-Request, Configure-
      Ack, Configure-Nak, Configure-Reject, Terminate-Request,
      Terminate-Ack and Code-Reject), two additional Codes 14 and 15
      (Reset-Request and Reset-Ack) are defined for this protocol.
      Other Codes should be treated as unrecognized and should result in
      Code-Rejects.

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RFC 1962                    PPP Compression                    June 1996

   Timeouts

      CCP packets may not be exchanged until PPP has reached the
      Network-Layer Protocol phase.  An implementation should be
      prepared to wait for Authentication and Link Quality Determination
      to finish before timing out waiting for a Configure-Ack or other