6Lo C. Bormann Internet-Draft Universitaet Bremen TZI Intended status: Standards Track April 03, 2016 Expires: October 5, 2016 Constrained Application Protocol (CoAP) over IEEE 802.15.4 Information Element for IETF draft-bormann-6lo-coap-802-15-ie-00.txt Abstract IEEE Std. 802.15.4-2015 defines Information Elements (IE), and draft- kivinen-802-15-ie defines a framework for using these IEs in IETF protocols. The present specification defines a way to transport CoAP messages in IEs. This can be used to perform CoAP exchanges with neighboring IEEE 802.15.4 nodes before there is IP connectivity, e.g., to configure that IP connectivity. draft-wang-6tisch-6top-coapie demonstrates example applications of this for 6TiSCH. Other areas of application are conceivable even in classic 6LoWPAN networks. 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 October 5, 2016. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. Bormann Expires October 5, 2016 [Page 1] Internet-Draft CoAP over IETF IE April 2016 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 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 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 2. CoAP over IETF IE . . . . . . . . . . . . . . . . . . . . . . 2 3. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction (See abstract for now.) 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. In this specification, the term "byte" is used in its now customary sense as a synonym for "octet". 2. CoAP over IETF IE The format of the IETF IE is defined in [I-D.kivinen-802-15-ie] as follows: Bormann Expires October 5, 2016 [Page 2] Internet-Draft CoAP over IETF IE April 2016 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-Type ID | | +-+-+-+-+-+-+-+-+ | ~ Sub-Type Content ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IETF IE Subtype Format Here, Sub-Type ID is the IANA allocated number specifying the sub- type of the IETF IE. The CoAP message is embedded in the IETF IE as follows: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver| T | TKL | Code | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Token (if any, TKL bytes) ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options (if any) ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 1 1 1 1 1| Payload (if any) ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IETF IE Subtype Format for CoAP This means that the combinations of Ver, T, TKL used by CoAP need to be allocated as Sub-Type IDs. Ver is always 1; T can be 0, 1, 2, 3, and TKL can be between 0 and 8 for T in 0..2 and 0 only for T = 3. This means that 3*9+1 = 28 Sub-Type IDs are needed. 3. Benefits Allocating 11 % of the code points (28 out of the 256) available for IETF IEs may seem like a large chunk. However, it enables the embedding of CoAP messages into IEs in an efficient way; any smaller allocation would need additional complexity for variable length encoding or would even always need an additional byte of overhead. 4. IANA Considerations This specification requests IANA to assign the following 28 code points in the registry for IETF IE Sub-type IDs to this specification: Bormann Expires October 5, 2016 [Page 3] Internet-Draft CoAP over IETF IE April 2016 +--------+-------------+ | Value | Sub-type ID | +--------+-------------+ | 64-72 | CoAP | | 80-88 | CoAP | | 96-104 | CoAP | | 112 | CoAP | +--------+-------------+ 5. Security Considerations The security considerations of [I-D.kivinen-802-15-ie] apply. Specifically, this means that object security (intrinsic in the resources accessed or explicit on the CoAP level) may be required. 6. Acknowledgments Much of the text here is taken from [I-D.kivinen-802-15-ie]. 7. References 7.1. Normative References [I-D.kivinen-802-15-ie] Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information Element for IETF", draft-kivinen-802-15-ie-00 (work in progress), March 2016. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 7.2. Informative References [I-D.wang-6tisch-6top-coapie] Wang, Q., Vilajosana, X., Watteyne, T., Sudhaakar, R., and P. Zand, "Transporting CoAP Messages over IEEE802.15.4e Information Elements", draft-wang-6tisch-6top-coapie-01 (work in progress), July 2015. Author's Address Bormann Expires October 5, 2016 [Page 4] Internet-Draft CoAP over IETF IE April 2016 Carsten Bormann Universitaet Bremen TZI Postfach 330440 Bremen D-28359 Germany Phone: +49-421-218-63921 Email: cabo@tzi.org Bormann Expires October 5, 2016 [Page 5]