rfc2395.txt

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4.5 Compressibility test

   There is no adaptive algorithm embodied in the LZS algorithm, for
   compressibility testing, as referenced in [IPCOMP].

5. Security Considerations

   This document does not add any further security considerations that
   [IPCOMP] and [Deutsch96] have already declared.

6. Acknowledgments

   The LZS details presented here are similar to those in PPP LZS-DCP
   Compression Protocol (LZS-DCP), [RFC-1967].

   The author wishes to thank the participants of the IPPCP working
   group mailing list whose discussion is currently active and is
   working to generate the protocol specification for integrating
   compression with IP.








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RFC 2395            IP Payload Compression Using LZS       December 1998


7. References

   [AH]       Kent, S., and R., Atkinson, "IP Authentication Header",
              RFC 2402, November 1998.

   [ANSI94]   American National Standards Institute, Inc., "Data
              Compression Method for Information Systems," ANSI X3.241-
              1994, August 1994.

   [Calgary]  Text Compression Corpus, University of Calgary, available
              at ftp://ftp.cpsc.ucalgary.ca/pub/projects/text.
              compression.corpus.

   [IPCOMP]   Shacham, A., "IP Payload Compression Protocol (IPComp)",
              RFC 2393, December 1998.

   [LZ1]      Lempel, A., and Ziv, J., "A Universal Algorithm for
              Sequential Data Compression", IEEE Transactions On
              Information Theory, Vol.  IT-23, No. 3, May 1977.

   [RFC-1962] Rand, D., "The PPP Compression Control Protocol (CCP)",
              RFC 1962, June 1996.

   [RFC-1967] Schneider, K., and R. Friend, "PPP LZS-DCP Compression
              Protocol (LZS-DCP)", RFC 1967, August 1996.

   [RFC-2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
              October 1996.

   [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [SECDOI]   Piper, D., "The Internet IP Security Domain of
              Interpretation for ISAKMP", RFC 2407, November 1998.

















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RFC 2395            IP Payload Compression Using LZS       December 1998


8. Authors' Addresses

   Robert Friend
   Hi/fn Inc.
   5973 Avenida Encinas
   Suite 110
   Carlsbad, CA  92008

   EMail: [e-mail]


   Robert Monsour
   Hi/fn Inc.
   2105 Hamilton Avenue
   Suite 230
   San Jose, CA 95125

   EMail: [e-mail]

































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RFC 2395            IP Payload Compression Using LZS       December 1998


9. Appendix: Compression Efficiency versus Datagram Size

   The following table offers some guidance on the compression
   efficiency that can be achieved as a function of datagram size.  Each
   entry in the table shows the compression ratio that was achieved when
   LZS was applied to a test file using datagrams of a specified size.

   The test file was the University of Calgary Text Compression Corpus
   [Calgary].  The Calgary Corpus consists of 18 files with a total size
   (all files) of 3.278MB.

    Datagram size,|
    bytes         |  64   128   256   512  1024  2048  4096  8192 16384
    --------------|----------------------------------------------------
    Compression   |1.18  1.28  1.43  1.58  1.74  1.91  2.04  2.11  2.14
    ratio         |



































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10.  Full Copyright Statement

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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