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lpwan Working Group                                       N. Sornin, Ed.
Internet-Draft                                                M. Coracin
Intended status: Informational                                   Semtech
Expires: September 6, 2018                                     I. Petrov
                                                                  Acklio
                                                                A. Yegin
                                                                Actility
                                                             J. Catalano
                                                                 Kerlink
                                                             V. Audebert
                                                                 EDF R&D
                                                          March 05, 2018


         Static Context Header Compression (SCHC) over LoRaWAN
              draft-petrov-lpwan-ipv6-schc-over-lorawan-01

Abstract

   The Static Context Header Compression (SCHC) specification describes
   generic header compression and fragmentation techniques for LPWAN
   (Low Power Wide Area Networks) technologies.  SCHC is a generic
   mechanism designed for great flexibility, so that it can be adapted
   for any of the LPWAN technologies.

   This document provides the adaptation of SCHC for use in LoRaWAN
   networks, and provides elements such as efficient parameterization
   and modes of operation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 6, 2018.






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Copyright Notice

   Copyright (c) 2018 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Static Context Header Compression Overview  . . . . . . . . .   3
   4.  LoRaWAN Architecture  . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Device classes (A, B, C) and interactions . . . . . . . .   5
     4.2.  Device addressing . . . . . . . . . . . . . . . . . . . .   5
     4.3.  General Message Types . . . . . . . . . . . . . . . . . .   6
     4.4.  LoRaWAN MAC Frames  . . . . . . . . . . . . . . . . . . .   6
   5.  SCHC over LoRaWAN . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Rule ID management  . . . . . . . . . . . . . . . . . . .   6
     5.2.  IID computation . . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Fragmentation . . . . . . . . . . . . . . . . . . . . . .   6
       5.3.1.  Reliability options . . . . . . . . . . . . . . . . .   6
       5.3.2.  Supporting multiple window sizes  . . . . . . . . . .   6
       5.3.3.  Downlink fragment transmission  . . . . . . . . . . .   6
       5.3.4.  SCHC behavior for devices in class A, B and C . . . .   6
   6.  Security considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   7
   Appendix B.  Note . . . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Static Context Header Compression (SCHC) specification
   [I-D.ietf-lpwan-ipv6-static-context-hc] describes generic header
   compression and fragmentation techniques that can be used on all
   LPWAN (Low Power Wide Area Networks) technologies defined in



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   [I-D.ietf-lpwan-overview].  Even though those technologies share a
   great number of common features like start-oriented topologies,
   network architecture, devices with mostly quite predictable
   communications, etc; they do have some slight differences in respect
   of payload sizes, reactiveness, etc.

   SCHC gives a generic framework that enables those devices to
   communicate with other Internet networks.  However, for efficient
   performance, some parameters and modes of operation need to be set
   appropriately for each of the LPWAN technologies.

   This document describes the efficient parameters and modes of
   operation when SCHC is used over LoRaWAN networks.

2.  Terminology

   This section defines the terminology and acronyms used in this
   document.  For all other definitions, please look up the SCHC
   specification [I-D.ietf-lpwan-ipv6-static-context-hc].

   o DevEUI: an IEEE EUI-64 identifier used to identify the device
   during the procedure while joining the network (Join Procedure)

   o DevAddr: a 32-bit non-unique identifier assigned to a device
   statically or dynamically after a Join Procedure (depending on the
   activation mode)

   o TBD: all significant LoRaWAN-related terms.

3.  Static Context Header Compression Overview

   This section contains a short overview of Static Context Header
   Compression (SCHC).  For a detailed description, refer to the full
   specification [I-D.ietf-lpwan-ipv6-static-context-hc].

   Static Context Header Compression (SCHC) avoids context
   synchronization, which is the most bandwidth-consuming operation in
   other header compression mechanisms such as RoHC [RFC5795].  Based on
   the fact that the nature of data flows is highly predictable in LPWAN
   networks, some static contexts may be stored on the Device (Dev).
   The contexts must be stored in both ends, and it can either be
   learned by a provisioning protocol or by out of band means or it can
   be pre-provisioned, etc.  The way the context is learned on both
   sides is out of the scope of this document.







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        Dev                                                 App
   +--------------+                                  +--------------+
   |APP1 APP2 APP3|                                  |APP1 APP2 APP3|
   |              |                                  |              |
   |      UDP     |                                  |     UDP      |
   |     IPv6     |                                  |    IPv6      |
   |              |                                  |              |
   |   SCHC C/D   |                                  |              |
   |   (context)  |                                  |              |
   +-------+------+                                  +-------+------+
            |   +--+     +----+     +---------+              .
            +~~ |RG| === |NGW | === |SCHC C/D |... Internet ..
                +--+     +----+     |(context)|
                                    +---------+

                          Figure 1: Architecture

   Figure 1 represents the architecture for compression/decompression,
   it is based on [I-D.ietf-lpwan-overview] terminology.  The Device is
   sending applications flows using IPv6 or IPv6/UDP protocols.  These
   flows are compressed by an Static Context Header Compression
   Compressor/Decompressor (SCHC C/D) to reduce headers size.  Resulting
   information is sent on a layer two (L2) frame to a LPWAN Radio
   Network (RG) which forwards the frame to a Network Gateway (NGW).
   The NGW sends the data to a SCHC C/D for decompression which shares
   the same rules with the Dev. The SCHC C/D can be located on the
   Network Gateway (NGW) or in another place as long as a tunnel is
   established between the NGW and the SCHC C/D.  The SCHC C/D in both
   sides must share the same set of Rules.  After decompression, the
   packet can be sent on the Internet to one or several LPWAN
   Application Servers (App).

   The SCHC C/D process is bidirectional, so the same principles can be
   applied in the other direction.

   In a LoRaWAN network, the RG is called a Gateway, the NGW is Network
   Server, and the SCHC C/D can be embedded in different places, for
   example in the Network Server and/or the Application Server.

   Next steps for this section: detailed overview of the LoRaWAN
   architecture and its mapping to the SCHC architecture.

4.  LoRaWAN Architecture

   An overview of LoRaWAN [lora-alliance-spec] protocol and architecture
   is described in [I-D.ietf-lpwan-overview].  Mapping between the LPWAN
   architecture entities as described in




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   [I-D.ietf-lpwan-ipv6-static-context-hc] and the ones in
   [lora-alliance-spec] is as follows:

   o Devices (Dev) are the end-devices or hosts (e.g. sensors,
   actuators, etc.).  There can be a very high density of devices per
   radio gateway.  This entity maps to the LoRaWAN End-device.

   o The Radio Gateway (RGW), which is the end point of the constrained
   link.  This entity maps to the LoRaWAN Gateway.

   o The Network Gateway (NGW) is the interconnection node between the
   Radio Gateway and the Internet.  This entity maps to the LoRaWAN
   Network Server.

   o LPWAN-AAA Server, which controls the user authentication and the
   applications.  This entity maps to the LoRaWAN Join Server.

   o Application Server (App).  The same terminology is used in LoRaWAN.

()   ()   ()       |                      +------+
 ()  () () ()     / \       +---------+   | Join |    () () () () () () /   \======|    ^    |===|Server|  +-----------+
()  ()   ()     |           | <--|--> |   +------+  |Application|    ()  ()  ()  ()  / \==========|    v    |=============|  Server   |
 ()  ()  ()   /   \         +---------+             +-----------+
End-Devices  Gateways     Network Server


                   Figure 1: LPWAN/LoRaWAN Architecture

   SCHC C/D (Compressor/Decompressor) and SCHC Fragmentation are
   performed on the LoRaWAN End-device and the Application Server.
   While the point-to-point link between the End-device and the
   Application Server constitutes single IP hop, the ultimate end-point
   of the IP communication may be an Internet node beyond the
   Application Server.  In other words, the LoRaWAN Application Server
   acts as the first hop IP router for the End-device.  Note that the
   Application Server and Network Server may be co-located, which
   effectively turns the Network/Application Server into the first hop
   IP router.

4.1.  Device classes (A, B, C) and interactions

   TBD

4.2.  Device addressing

   TBD





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4.3.  General Message Types

   TBD

4.4.  LoRaWAN MAC Frames

   TBD

5.  SCHC over LoRaWAN

5.1.  Rule ID management

   Rule ID can be stored and transported in the FPort field of the
   LoRaWAN MAC frame.

   TBD

5.2.  IID computation

   TBD

5.3.  Fragmentation

   TBD

5.3.1.  Reliability options

   TBD

5.3.2.  Supporting multiple window sizes

   TBD

5.3.3.  Downlink fragment transmission

   TBD

5.3.4.  SCHC behavior for devices in class A, B and C

   TBD

6.  Security considerations

   TBD







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7.  Acknowledgements

   TBD

8.  References

8.1.  Normative References

   [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>.

   [RFC5795]  Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
              Header Compression (ROHC) Framework", RFC 5795,
              DOI 10.17487/RFC5795, March 2010,
              <https://www.rfc-editor.org/info/rfc5795>.

   [RFC7136]  Carpenter, B. and S. Jiang, "Significance of IPv6
              Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136,
              February 2014, <https://www.rfc-editor.org/info/rfc7136>.

8.2.  Informative References

   [I-D.ietf-lpwan-ipv6-static-context-hc]
              Minaburo, A., Toutain, L., and C. Gomez, "LPWAN Static
              Context Header Compression (SCHC) and fragmentation for
              IPv6 and UDP", draft-ietf-lpwan-ipv6-static-context-hc-10
              (work in progress), February 2018.

   [I-D.ietf-lpwan-overview]
              Farrell, S., "LPWAN Overview", draft-ietf-lpwan-
              overview-10 (work in progress), February 2018.

   [lora-alliance-spec]
              Alliance, L., "LoRaWAN Specification Version V1.0.2",
              <http://portal.lora-
              alliance.org/DesktopModules/Inventures_Document/
              FileDownload.aspx?ContentID=1398>.

Appendix A.  Examples

Appendix B.  Note








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Authors' Addresses

   Nicolas Sornin (editor)
   Semtech
   14 Chemin des Clos
   Meylan
   France

   Email: nsornin@semtech.com


   Michael Coracin
   Semtech
   14 Chemin des Clos
   Meylan
   France

   Email: mcoracin@semtech.com


   Ivaylo Petrov
   Acklio
   2bis rue de la Chataigneraie
   35510 Cesson-Sevigne Cedex
   France

   Email: ivaylo@ackl.io


   Alper Yegin
   Actility
   .
   Paris, Paris
   France

   Email: alper.yegin@actility.com


   Julien Catalano
   Kerlink
   1 rue Jacqueline Auriol
   35235 Thorigne-Fouillard
   France

   Email: j.catalano@kerlink.fr






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   Vincent AUDEBERT
   EDF R&D
   7 bd Gaspard Monge
   91120 PALAISEAU
   FRANCE

   Email: vincent.audebert@edf.fr












































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