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Versions: 00 01 02

Network Working Group                                       R. Moskowitz
Internet-Draft                                                  S. Hares
Intended status: Standards Track                                  Huawei
Expires: December 29, 2017                                   I. Faynberg
                                              Stargazers Consulting, LLC
                                                                   H. Lu
                                                                 Retired
                                                             P. Giacomin
                                                               FreeLance
                                                           June 27, 2017


                                 GPCOMP
                     draft-moskowitz-gpcomp-02.txt

Abstract

   This document describes a protocol intended to provide lossless
   compression for use within any datagram.  It is particularly intended
   for use in encrypted datagrams where lower-level compression is
   ineffective.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 29, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements Terminology  . . . . . . . . . . . . . . . .   3
     2.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Compression Process . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Compressed Payload  . . . . . . . . . . . . . . . . . . .   3
     3.2.  Uncompressing Conundrum . . . . . . . . . . . . . . . . .   4
     3.3.  Non-Expansion Policy  . . . . . . . . . . . . . . . . . .   4
   4.  Compressed Datagram Structure . . . . . . . . . . . . . . . .   5
     4.1.  Implied Structure . . . . . . . . . . . . . . . . . . . .   5
     4.2.  GPComp header for Explicit Structure  . . . . . . . . . .   5
   5.  Negotiating GPComp  . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  The GPCA  . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  Using IKEv2 . . . . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Using HIP . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Generic payload compression is a protocol to reduce the size of most
   datagrams.  This protocol will increase the overall communication
   performance by compressing the datagrams, provided the participating
   devices have sufficient computation power, through either CPU
   capacity or a compression coprocessor, and the communication is over
   constrained links.

   Generic payload compression is especially useful when encryption is
   applied to datagrams.  Encrypting a datagram causes the data to be
   random in nature, rendering compression at lower protocol layers
   ineffective.

   This document defines the Generic payload compression protocol
   (GPComp), a GPComp packet structure, the GPComp Association (GPCA),
   and several methods to negotiate the GPCA.



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   Other documents shall specify how a specific compression algorithm
   can be used with the Generic payload compression protocol.  Such
   algorithms are beyond the scope of this document.

   This document draws heavily on IPCOMP [RFC3173].

2.  Terms and Definitions

2.1.  Requirements Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.2.  Definitions

   GPCA:  The Generic Payload Compression Protocol Association.  This is
      the collection of attributes and values that define how GPComp
      operates.

3.  Compression Process

   The compression processing has two phases: compressing of outbound
   datagrams ("compression") and decompressing of inbound datagrams
   ("decompression").  The compression processing MUST be lossless,
   ensuring that the datagram, after being compressed and decompressed,
   is identical to the original datagram.

   Each datagram is compressed and decompressed by itself without any
   relation to other datagrams ("stateless compression"), as datagrams
   may arrive out of order or not arrive at all.

   Processing of inbound datagrams MUST support both compressed and non-
   compressed datagrams, in order to meet the non-expansion policy
   requirements, as defined in Section 3.3.

3.1.  Compressed Payload

   Compression is applied to a single datagram.  The size of a
   compressed payload, generated by the compression algorithm, MUST be
   in whole octet units.

   As compression is optional for each datagram associated within the
   GPCA, an identification mechanism is REQUIRED for each datagram.
   Minimally this can be a single option bit within the datagram's
   header (if it has one).  Alternatively, the GPComp header, defined in
   Section 4.2, is inserted immediately preceding the compressed




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   payload.  The receiving side MUST be able to distinguish between
   compressed and uncompressed payloads.

3.2.  Uncompressing Conundrum

   The receiver MUST be able to recognize the condition of no
   compression for the case where there is no datagram header option
   flag for compression and only the presense of the GPComp header
   indicates a compressed payload.  In this case, the payload itself has
   no indication that GPComp is enabled for the payload, but there is
   nothing to decompress.  The receiving process has to be able to
   identify the payload as lacking the GPComp header and act
   appropriately.  Thus it is best if there is a datagram header
   compression flag (for example in SSE [I-D.moskowitz-sse]) and the
   GPComp header is not even used.

3.3.  Non-Expansion Policy

   If the total size of a compressed payload and the GPComp header (if
   present) is not smaller than the size of the original payload, the
   datagram MUST be sent in the original non-compressed form.  To
   clarify: If an datagram is sent non-compressed, no GPComp header is
   added to the datagram.  This policy ensures saving the decompression
   processing cycles and avoiding incurring datagram fragmentation if
   the expanded datagram is larger than the MTU.  It does present a
   potential conundrum Section 3.2 to the receiver.

   Small datagrams are likely to expand as a result of compression.
   Therefore, a numeric threshold should be applied before compression,
   where datagrams of size smaller than the threshold are sent in the
   original form without attempting compression.  The numeric threshold
   is implementation dependent.

   A datagram payload with compressed content tends not to compress any
   further.  The previously compressed payload may be the result of
   external processes, such as compression applied by an upper layer in
   the communication stack, or by an off-line compression utility.  An
   adaptive algorithm should be implemented to avoid the performance
   hit.  For example, if the compression of i consecutive IP datagrams
   of an GPCA fails, the next several datagrams, say k, are sent without
   attempting compression.  If then the next j datagrams also fail to
   compress, a larger number of datagrams, say k+n, are sent without
   attempting compression.  Once a datagram is compressed successfully,
   the normal process of IPComp restarts.  Such an adaptive algorithm,
   including all the related thresholds, is implementation dependent.

   During the processing of the payload, the compression algorithm MAY
   periodically apply a test to determine the compressibility of the



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   processed data, similar to the requirements of [V42BIS].  The nature
   of the test is algorithm dependent.  Once the compression algorithm
   detects that the data is non-compressible, the algorithm SHOULD stop
   processing the data, and the payload is sent in the original non-
   compressed form.

4.  Compressed Datagram Structure

   The compressed datagram structure for GPComp can be implied or
   explicit.  The implied structure is used with datagrams that have a
   header field with option flags and a length field or end-of-datagram
   identifier.  The explicit structure uses the GPComp header.

4.1.  Implied Structure

   The implied structure takes one option flag bit in the datagram
   header.  This bit is ONE if that datagram is compressed or ZERO if
   not compressed.  The compression algorithm is specified within the
   GPCA.  The implied structure can be used within SSE.

4.2.  GPComp header for Explicit Structure

   The GPComp header is used for datagrams that do not have a defined
   header with an options field, or do not have an available bit in the
   header to flag compression status.  IPFIX [RFC7011] and NETCONF
   [RFC6536] use such a datagram.

   The GPComp header is identical to the IPComp header [RFC3173].  This
   is for done for simplicity sake.  Although it is possible to design a
   GPComp header of only 2 bytes, this would break the typical 32 bit
   word alignment in Internet Protocol headers.  In many uses, the Next
   Header field will be NULL; this is set by the GPCA.

5.  Negotiating GPComp

   The use of GPComp and its options (e.g. compression algorithm) should
   be part of the communication start up process.  Although GPComp can
   be manually set up, this may result in a lack of agility in
   compression algorithm selection.  That is, only one algorithm is used
   and cannot easily be changed.  Thus manual set up for GPComp should
   be limited to testing needs.

   An application may use any internal set up mechanism for negotiating
   GPComp.  However, as compression is frequently used in conjunction
   with encryption, the application may call a Key Management Protocol
   (KMP) and request that the KMP set up GPComp.





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5.1.  The GPCA

   The GPCA is a data structure that controls the operation of GPComp.
   The content of the GPCA is application dependent but it will always
   include the Compression Parameter Index (CPI) as defined in IPCOMP.

5.2.  Using IKEv2

   At set up, and application may call IKEv2 [RFC7296].  This may be to
   enable ESP in Transport Mode [RFC4303] or SSE for secure
   communications.  It the same time, IKE may be instructed to negotiate
   IPCOMP, but the application will use the negotiated IPCOMP CPI for
   GPComp.

5.3.  Using HIP

   At set up, and application may call HIPv2 [RFC7401] or HIP-DEX
   [I-D.ietf-hip-dex].  This may be to enable ESP in BEET Mode [RFC7402]
   or SSE for secure communications.

   HIP does not currently include a negotiation for compression.  A
   GPCOMP_INFO parameter is proposed in [I-D.moskowitz-ssls-hip].  It is
   unclear at this time if this could also be used for IPCOMP, or if a
   separate parameter is needed for it.

6.  IANA Considerations

   In [I-D.moskowitz-ssls-hip], IANA is requested to assign a HIP
   parameter value for the Compression Transform.

7.  Security Considerations

   TBD

8.  Contributors

   TBD

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.





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   [RFC3173]  Shacham, A., Monsour, B., Pereira, R., and M. Thomas, "IP
              Payload Compression Protocol (IPComp)", RFC 3173,
              DOI 10.17487/RFC3173, September 2001,
              <http://www.rfc-editor.org/info/rfc3173>.

9.2.  Informative References

   [I-D.ietf-hip-dex]
              Moskowitz, R. and R. Hummen, "HIP Diet EXchange (DEX)",
              draft-ietf-hip-dex-05 (work in progress), February 2017.

   [I-D.moskowitz-sse]
              Moskowitz, R., Faynberg, I., Lu, H., Hares, S., and P.
              Giacomin, "Session Security Envelope", draft-moskowitz-
              sse-04 (work in progress), October 2016.

   [I-D.moskowitz-ssls-hip]
              Moskowitz, R., Xia, L., Faynberg, I., Hares, S., and P.
              Giacomin, "Secure Session Layer Services KMP via HIP",
              draft-moskowitz-ssls-hip-01 (work in progress), October
              2016.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <http://www.rfc-editor.org/info/rfc4303>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <http://www.rfc-editor.org/info/rfc6536>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <http://www.rfc-editor.org/info/rfc7011>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <http://www.rfc-editor.org/info/rfc7296>.

   [RFC7401]  Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
              Henderson, "Host Identity Protocol Version 2 (HIPv2)",
              RFC 7401, DOI 10.17487/RFC7401, April 2015,
              <http://www.rfc-editor.org/info/rfc7401>.





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   [RFC7402]  Jokela, P., Moskowitz, R., and J. Melen, "Using the
              Encapsulating Security Payload (ESP) Transport Format with
              the Host Identity Protocol (HIP)", RFC 7402,
              DOI 10.17487/RFC7402, April 2015,
              <http://www.rfc-editor.org/info/rfc7402>.

   [V42BIS]   CCITT, "Data Compression Procedures for Data Circuit
              Terminating Equipment (DCE) Using Error Correction
              Procedures", Recommendation V.42 bis, January 1990.

Authors' Addresses

   Robert Moskowitz
   Huawei
   Oak Park, MI  48237

   Email: rgm@labs.htt-consult.com


   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com


   Igor Faynberg
   Stargazers Consulting, LLC
   East Brunswick, NJ  08816
   USA

   Email: igorfaynberg@gmail.com


   Huilan Lu
   Retired

   Email: huilanlu2@gmail.com


   Pierpaolo Giacomin
   FreeLance

   Email: yrz@anche.no





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