Internet DRAFT - draft-gomez-6lo-schc-dispatch

draft-gomez-6lo-schc-dispatch







6lo Working Group                                               C. Gomez
Internet-Draft                                                       UPC
Intended status: Standards Track                      September 21, 2020
Expires: March 25, 2021


 IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Dispatch
                             Type for SCHC
                    draft-gomez-6lo-schc-dispatch-01

Abstract

   A new framework called Static Context Header Compression (SCHC) has
   been designed with the primary goal of supporting IPv6 over Low Power
   Wide Area Network (LPWAN) technologies [RFC8724].  One of the SCHC
   components is a header compression mechanism.  If used properly, SCHC
   header compression allows a greater compression ratio than that
   achievable with traditional 6LoWPAN header compression [RFC6282].
   For this reason, it may make sense to use SCHC header compression in
   some 6LoWPAN environments.  This document defines a 6LoWPAN Dispatch
   Type to signal when a packet header has been compressed by using SCHC
   header compression.

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 https://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 March 25, 2021.

Copyright Notice

   Copyright (c) 2020 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
   (https://trustee.ietf.org/license-info) in effect on the date of



Gomez                    Expires March 25, 2021                 [Page 1]

Internet-Draft       6LoWPAN Dispatch Type for SCHC       September 2020


   publication of this document.  Please review these documents
   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.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  Frame Format  . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  SCHC Dispatch Type  . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   RFC 6282 is the main specification for IPv6 over Low power Wireless
   Personal Area Network (6LoWPAN) IPv6 header compression [RFC6282].
   This RFC was designed assuming IEEE 802.15.4 as the layer below the
   6LoWPAN adaptation layer, and it has also been reused (with proper
   adaptations) for IPv6 header compression over many other technologies
   relatively similar to IEEE 802.15.4 in terms of characteristics such
   as physical layer bit rate, layer 2 maximum payload size, etc.
   Examples of such technologies comprise BLE, DECT-ULE, ITU G.9959, MS/
   TP, NFC, and PLC.  RFC 6282 provides additional functionality, such
   as a mechanism for UDP header compression.

   In the best cases, RFC 6282 allows to compress a 40-byte IPv6 header
   down to a 2-byte compressed header (for link-local interactions) or a
   3-byte compressed header (when global IPv6 addresses are used).  On
   the other hand, an RFC 6282 compressed UDP header has a typical size
   of 4 bytes.  Therefore, in advantageous conditions, a 48-byte
   uncompressed IPv6/UDP header may be compressed down to a 6-byte
   format (when using link-local addresses) or a 7-byte format (for
   global interactions) by using RFC 6282.

   Recently, a new framework called Static Context Header Compression
   (SCHC) has been designed with the primary goal of supporting IPv6
   over Low Power Wide Area Network (LPWAN) technologies [RFC8724].
   SCHC comprises header compression and fragmentation functionality
   tailored to the extraordinary constraints of LPWAN technologies,



Gomez                    Expires March 25, 2021                 [Page 2]

Internet-Draft       6LoWPAN Dispatch Type for SCHC       September 2020


   which are more severe than those exhibited by IEEE 802.15.4 or other
   relatively similar technologies.

   SCHC header compression allows a greater compression ratio than that
   of RFC 6282.  If used properly, SCHC allows to compress an IPv6/UDP
   header down to e.g. a single byte.  Therefore, it may make sense to
   use SCHC header compression in some 6LoWPAN environments [I-
   D.toutain-6lo-6lo-and-schc], considering its greater efficiency.

   If SCHC header compression is added to the panoply of header
   compression mechanisms used in 6LoWPAN environments, then there is a
   need to signal when a packet header has been compressed by using
   SCHC.  To this end, in its current form, the present document
   specifies a 6LoWPAN Dispatch Type for SCHC header compression, based
   on exploiting RFC 8025 Dispatch type space [RFC8025].

2.  Conventions used in this document

   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 [RFC2119].

3.  Frame Format

   Figure 1 illustrates the content of an encapsulated, SCHC compressed,
   IPv6 datagram:


            +---------------+-------------+---------+
            | SCHC Dispatch | SCHC Header | Payload |
            +---------------+-------------+---------+


           Figure 1: Encapsulated, SCHC compressed IPv6 datagram

   The SCHC Dispatch is a 6LoWPAN Dispatch Type that indicates that the
   next field is a SCHC Header.  The latter corresponds to a packet
   header that has been compressed by using SCHC.  As defined in
   [RFC8724], the SCHC Header comprises a Rule ID, and a compression
   residue.  (Note: more details, including a discussion on padding, to
   be added.)

4.  SCHC Dispatch Type

   This section defines the 6LoWPAN Dispatch Type called "SCHC
   Dispatch", by using the RFC 8025 concept of "pages".  With the aim to
   minimize overhead, the present document allocates a whole page (Page
   2) for the SCHC Dispatch Type:



Gomez                    Expires March 25, 2021                 [Page 3]

Internet-Draft       6LoWPAN Dispatch Type for SCHC       September 2020


   SCHC Dispatch Type bit pattern: 11110010 (Page 2 (Note: to be
   confirmed by IANA))

   For example, two bytes may be used for the SCHC Dispatch plus the
   Rule ID, which offers a Rule ID space of 256 possible Rule IDs.

5.  IANA Considerations

   This document requests the allocation of the Dispatch Type Field bit
   pattern 11110010 (Page 2) as SCHC Dispatch Type.

6.  Security Considerations

   TBD

7.  Acknowledgments

   Ana Minaburo and Laurent Toutain suggested for the first time the use
   of SCHC in environments where 6LoWPAN has traditionally been used.
   Laurent Toutain made comments that helped shape this document.

   Carles Gomez has been funded in part by the Spanish Government
   through project PID2019-106808RA-I00, and by Secretaria
   d'Universitats i Recerca del Departament d'Empresa i Coneixement de
   la Generalitat de Catalunya 2017 through grant SGR 376.

8.  References

8.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <https://www.rfc-editor.org/info/rfc4944>.

   [RFC6282]  Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              DOI 10.17487/RFC6282, September 2011,
              <https://www.rfc-editor.org/info/rfc6282>.







Gomez                    Expires March 25, 2021                 [Page 4]

Internet-Draft       6LoWPAN Dispatch Type for SCHC       September 2020


   [RFC8025]  Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
              Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
              RFC 8025, DOI 10.17487/RFC8025, November 2016,
              <https://www.rfc-editor.org/info/rfc8025>.

   [RFC8724]  Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
              Zuniga, "SCHC: Generic Framework for Static Context Header
              Compression and Fragmentation", RFC 8724,
              DOI 10.17487/RFC8724, April 2020,
              <https://www.rfc-editor.org/info/rfc8724>.

8.2.  Informative References

   [I-D.toutain-6lo-6lo-and-schc]
              Minaburo, A. and L. Toutain, "Comparison of 6lo and SCHC",
              draft-toutain-6lo-6lo-and-schc-00 (work in progress),
              November 2019.

Author's Address

   Carles Gomez
   UPC
   C/Esteve Terradas, 7
   Castelldefels  08860
   Spain

   Email: carlesgo@entel.upc.edu
























Gomez                    Expires March 25, 2021                 [Page 5]