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 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 September 6, 2018. Sornin, et al. Expires September 6, 2018 [Page 1] Internet-Draft SCHC-over-LORA March 2018 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 Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of 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. 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 Sornin, et al. Expires September 6, 2018 [Page 2] Internet-Draft SCHC-over-LORA March 2018 [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. Sornin, et al. Expires September 6, 2018 [Page 3] Internet-Draft SCHC-over-LORA March 2018 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 Sornin, et al. Expires September 6, 2018 [Page 4] Internet-Draft SCHC-over-LORA March 2018 [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 Sornin, et al. Expires September 6, 2018 [Page 5] Internet-Draft SCHC-over-LORA March 2018 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 Sornin, et al. Expires September 6, 2018 [Page 6] Internet-Draft SCHC-over-LORA March 2018 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, . [RFC5795] Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust Header Compression (ROHC) Framework", RFC 5795, DOI 10.17487/RFC5795, March 2010, . [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, February 2014, . 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", . Appendix A. Examples Appendix B. Note Sornin, et al. Expires September 6, 2018 [Page 7] Internet-Draft SCHC-over-LORA March 2018 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 Sornin, et al. Expires September 6, 2018 [Page 8] Internet-Draft SCHC-over-LORA March 2018 Vincent AUDEBERT EDF R&D 7 bd Gaspard Monge 91120 PALAISEAU FRANCE Email: vincent.audebert@edf.fr Sornin, et al. Expires September 6, 2018 [Page 9]