RFC 1962 (rfc1962) - Page 2 of 9

The PPP Compression Control Protocol (CCP)

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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