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]