--- 1/draft-ietf-6tisch-tsch-04.txt 2015-01-08 09:14:56.494776783 -0800 +++ 2/draft-ietf-6tisch-tsch-05.txt 2015-01-08 09:14:56.538777861 -0800 @@ -1,22 +1,22 @@ 6TiSCH T. Watteyne, Ed. Internet-Draft Linear Technology Intended status: Informational MR. Palattella -Expires: June 22, 2015 University of Luxembourg +Expires: July 12, 2015 University of Luxembourg LA. Grieco Politecnico di Bari - December 19, 2014 + January 8, 2015 Using IEEE802.15.4e TSCH in an IoT context: Overview, Problem Statement and Goals - draft-ietf-6tisch-tsch-04 + draft-ietf-6tisch-tsch-05 Abstract This document describes the environment, problem statement, and goals for using the IEEE802.15.4e TSCH MAC protocol in the context of LLNs. The set of goals enumerated in this document form an initial set only. Status of This Memo @@ -26,25 +26,25 @@ 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 June 22, 2015. + This Internet-Draft will expire on July 12, 2015. Copyright Notice - Copyright (c) 2014 IETF Trust and the persons identified as the + Copyright (c) 2015 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 (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 @@ -64,42 +64,42 @@ 4.6. Dataflow Control . . . . . . . . . . . . . . . . . . . . 8 4.7. Deterministic Behavior . . . . . . . . . . . . . . . . . 8 4.8. Scheduling Mechanisms . . . . . . . . . . . . . . . . . . 9 4.9. Secure Communication . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . 10 - 8.3. External Informative References . . . . . . . . . . . . . 13 - Appendix A. TSCH Protocol Highlights . . . . . . . . . . . . . . 15 - A.1. Timeslots . . . . . . . . . . . . . . . . . . . . . . . . 15 - A.2. Slotframes . . . . . . . . . . . . . . . . . . . . . . . 16 - A.3. Node TSCH Schedule . . . . . . . . . . . . . . . . . . . 16 - A.4. Cells and Bundles . . . . . . . . . . . . . . . . . . . . 16 - A.5. Dedicated vs. Shared Cells . . . . . . . . . . . . . . . 17 - A.6. Absolute Slot Number . . . . . . . . . . . . . . . . . . 17 - A.7. Channel Hopping . . . . . . . . . . . . . . . . . . . . . 18 - A.8. Time Synchronization . . . . . . . . . . . . . . . . . . 18 - A.9. Power Consumption . . . . . . . . . . . . . . . . . . . . 19 - A.10. Network TSCH Schedule . . . . . . . . . . . . . . . . . . 19 - A.11. Join Process . . . . . . . . . . . . . . . . . . . . . . 20 - A.12. Information Elements . . . . . . . . . . . . . . . . . . 20 - A.13. Extensibility . . . . . . . . . . . . . . . . . . . . . . 20 - Appendix B. TSCH Gotchas . . . . . . . . . . . . . . . . . . . . 21 - B.1. Collision Free Communication . . . . . . . . . . . . . . 21 - B.2. Multi-Channel vs. Channel Hopping . . . . . . . . . . . . 21 - B.3. Cost of (continuous) Synchronization . . . . . . . . . . 21 - B.4. Topology Stability . . . . . . . . . . . . . . . . . . . 22 - B.5. Multiple Concurrent Slotframes . . . . . . . . . . . . . 22 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 + 8.3. External Informative References . . . . . . . . . . . . . 12 + Appendix A. TSCH Protocol Highlights . . . . . . . . . . . . . . 13 + A.1. Timeslots . . . . . . . . . . . . . . . . . . . . . . . . 13 + A.2. Slotframes . . . . . . . . . . . . . . . . . . . . . . . 14 + A.3. Node TSCH Schedule . . . . . . . . . . . . . . . . . . . 14 + A.4. Cells and Bundles . . . . . . . . . . . . . . . . . . . . 14 + A.5. Dedicated vs. Shared Cells . . . . . . . . . . . . . . . 15 + A.6. Absolute Slot Number . . . . . . . . . . . . . . . . . . 15 + A.7. Channel Hopping . . . . . . . . . . . . . . . . . . . . . 16 + A.8. Time Synchronization . . . . . . . . . . . . . . . . . . 16 + A.9. Power Consumption . . . . . . . . . . . . . . . . . . . . 17 + A.10. Network TSCH Schedule . . . . . . . . . . . . . . . . . . 17 + A.11. Join Process . . . . . . . . . . . . . . . . . . . . . . 18 + A.12. Information Elements . . . . . . . . . . . . . . . . . . 18 + A.13. Extensibility . . . . . . . . . . . . . . . . . . . . . . 18 + Appendix B. TSCH Gotchas . . . . . . . . . . . . . . . . . . . . 19 + B.1. Collision Free Communication . . . . . . . . . . . . . . 19 + B.2. Multi-Channel vs. Channel Hopping . . . . . . . . . . . . 19 + B.3. Cost of (continuous) Synchronization . . . . . . . . . . 19 + B.4. Topology Stability . . . . . . . . . . . . . . . . . . . 20 + B.5. Multiple Concurrent Slotframes . . . . . . . . . . . . . 20 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 1. Introduction IEEE802.15.4e [IEEE802154e] was published in 2012 as an amendment to the Medium Access Control (MAC) protocol defined by the IEEE802.15.4-2011 [IEEE802154] standard. IEEE802.15.4e will be rolled into the next revision of IEEE802.15.4, scheduled to be published in 2015. The Timeslotted Channel Hopping (TSCH) mode of IEEE802.15.4e is the object of this document. @@ -381,25 +381,28 @@ 2. Provide a mechanism for such deterministic flows to coexist with bursty or infrequent traffic flows of different priorities. 4.8. Scheduling Mechanisms Several scheduling mechanisms can be envisioned, and possibly coexist in the same network. For example, [I-D.phinney-roll-rpl-industrial-applicability] describes how the allocation of bandwidth can be optimized by an external Path - Computation Element (PCE). Alternatively, two neighbor nodes can - adapt the number of cells autonomously by monitoring the amount of - traffic, and negotiating the allocation to extra cell when needed. - This mechanism can be used to establish multi-hop paths in a fashion - similar to RSVP. The LLC needs to: + Computation Element (PCE). Another centralized (PCE-based) traffic- + aware scheduling algorithm is defined in [TASA-PIMRC]. + Alternatively, two neighbor nodes can adapt the number of cells + autonomously by monitoring the amount of traffic, and negotiating the + allocation to extra cell when needed. An example of decentralized + algorithm is provided in [tinka10decentralized]. This mechanism can + be used to establish multi-hop paths in a fashion similar to RSVP. + The LLC needs to: 1. Provide a mechanism for two 6TiSCH devices to negotiate the allocation and deallocation of cells between them. 2. Provide a mechanism for device to monitor and manage the 6TiSCH capabilities of a node several hops away. 3. Define an mechanism for these different scheduling mechanisms to coexist in the same network. @@ -426,24 +429,25 @@ This memo is an informational overview of existing standards, and does define any new mechanisms or protocols. It does describe the need for the 6TiSCH WG to define a secure solution. In particular, Section 4.1 describes security in the join process. Section 4.9 discusses data frame protection. 7. Acknowledgments - Special thanks to Jonathan Simon for his review and valuable - comments. Thanks to Guillaume Gaillard and Dominique Barthel for - their in-depth review. Thanks to the IoT6 European Project (STREP) - of the 7th Framework Program (Grant 288445). + Special thanks to Dominique Barthel, Patricia Brett, Guillaume + Gaillard, Pat Kinney, Ines Robles, Timothy J. Salo, Jonathan Simon, + Rene Struik, Xavi Vilajosana for reviewing the document and providing + valuable feedback. Thanks to the IoT6 European Project (STREP) of + the 7th Framework Program (Grant 288445). 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 8.2. Informative References @@ -454,24 +458,20 @@ Constrained-Node Networks", RFC 7228, May 2014. [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and Lossy Networks", RFC 7102, January 2014. [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem Statement and Requirements for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Routing", RFC 6606, May 2012. - [RFC6568] Kim, E., Kaspar, D., and JP. Vasseur, "Design and - Application Spaces for IPv6 over Low-Power Wireless - Personal Area Networks (6LoWPANs)", RFC 6568, April 2012. - [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks", RFC 6550, March 2012. [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, September 2011. [RFC5867] Martocci, J., De Mil, P., Riou, N., and W. Vermeylen, @@ -503,101 +503,31 @@ Address Autoconfiguration", RFC 4862, September 2007. [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood, "Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July 2004. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. - [I-D.ietf-6tisch-6top-interface] - Wang, Q., Vilajosana, X., and T. Watteyne, "6TiSCH - Operation Sublayer (6top) Interface", draft-ietf-6tisch- - 6top-interface-02 (work in progress), October 2014. - - [I-D.ietf-6tisch-architecture] - Thubert, P., Watteyne, T., and R. Assimiti, "An - Architecture for IPv6 over the TSCH mode of IEEE - 802.15.4e", draft-ietf-6tisch-architecture-04 (work in - progress), October 2014. - - [I-D.ietf-6tisch-coap] - Sudhaakar, R. and P. Zand, "6TiSCH Resource Management and - Interaction using CoAP", draft-ietf-6tisch-coap-02 (work - in progress), December 2014. - - [I-D.ietf-6tisch-minimal] - Vilajosana, X. and K. Pister, "Minimal 6TiSCH - Configuration", draft-ietf-6tisch-minimal-04 (work in - progress), November 2014. - [I-D.ietf-6tisch-terminology] Palattella, M., Thubert, P., Watteyne, T., and Q. Wang, "Terminology in IPv6 over the TSCH mode of IEEE 802.15.4e", draft-ietf-6tisch-terminology-02 (work in progress), July 2014. [I-D.wang-6tisch-6top-sublayer] Wang, Q., Vilajosana, X., and T. Watteyne, "6TiSCH Operation Sublayer (6top)", draft-wang-6tisch-6top- sublayer-01 (work in progress), July 2014. - [I-D.thubert-roll-forwarding-frags] - Thubert, P. and J. Hui, "LLN Fragment Forwarding and - Recovery", draft-thubert-roll-forwarding-frags-02 (work in - progress), September 2013. - - [I-D.tsao-roll-security-framework] - Tsao, T., Alexander, R., Daza, V., and A. Lozano, "A - Security Framework for Routing over Low Power and Lossy - Networks", draft-tsao-roll-security-framework-02 (work in - progress), March 2010. - - [I-D.thubert-roll-asymlink] - Thubert, P., "RPL adaptation for asymmetrical links", - draft-thubert-roll-asymlink-02 (work in progress), - December 2011. - - [I-D.ietf-roll-terminology] - Vasseur, J., "Terms used in Routing for Low power And - Lossy Networks", draft-ietf-roll-terminology-13 (work in - progress), October 2013. - - [I-D.ietf-roll-p2p-rpl] - Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J. - Martocci, "Reactive Discovery of Point-to-Point Routes in - Low Power and Lossy Networks", draft-ietf-roll-p2p-rpl-17 - (work in progress), March 2013. - - [I-D.ietf-roll-trickle-mcast] - Hui, J. and R. Kelsey, "Multicast Protocol for Low power - and Lossy Networks (MPL)", draft-ietf-roll-trickle- - mcast-11 (work in progress), November 2014. - - [I-D.thubert-6lowpan-backbone-router] - Thubert, P., "6LoWPAN Backbone Router", draft-thubert- - 6lowpan-backbone-router-03 (work in progress), February - 2013. - - [I-D.sarikaya-core-sbootstrapping] - Sarikaya, B., Ohba, Y., Moskowitz, R., Cao, Z., and R. - Cragie, "Security Bootstrapping Solution for Resource- - Constrained Devices", draft-sarikaya-core- - sbootstrapping-04 (work in progress), April 2012. - - [I-D.gilger-smart-object-security-workshop] - Gilger, J. and H. Tschofenig, "Report from the 'Smart - Object Security Workshop', 23rd March 2012, Paris, - France", draft-gilger-smart-object-security-workshop-00 - (work in progress), October 2012. - [I-D.phinney-roll-rpl-industrial-applicability] Phinney, T., Thubert, P., and R. Assimiti, "RPL applicability in industrial networks", draft-phinney-roll- rpl-industrial-applicability-02 (work in progress), February 2013. 8.3. External Informative References [IEEE802154e] IEEE standard for Information Technology, "IEEE std. @@ -645,64 +575,35 @@ publications/2008/TSMP%20DSN08.pdf>. [watteyne09reliability] Watteyne, T., Mehta, A., and K. Pister, "Reliability Through Frequency Diversity: Why Channel Hopping Makes Sense", International Conference on Performance Evaluation of Wireless Ad Hoc, Sensor, and Ubiquitous Networks (PE- WASUN) 2009, Oct. 2009, . - [kerkez09feasibility] - Kerkez, B., Watteyne, T., and M. Magliocco, "Feasibility - analysis of controller design for adaptive channel - hopping", International Workshop on Performance - Methodologies and Tools for Wireless Sensor Networks - (WSNPERF) 2009, Oct. 2009, . - [TASA-PIMRC] Palattella, MR., Accettura, N., Dohler, M., Grieco, LA., and G. Boggia, "Traffic Aware Scheduling Algorithm for Multi-Hop IEEE 802.15.4e Networks", IEEE PIMRC 2012, Sept. 2012, < http://www.cttc.es/resources/ doc/120531-submitted-tasa-25511.pdf>. - [TASA-SENSORS] - Palattella, MR., Accettura, N., Dohler, M., Grieco, LA., - and G. Boggia, "Traffic-Aware Time-Critical Scheduling In - Heavily Duty-Cycled IEEE 802.15.4e For An Industrial IoT", - IEEE SENSORS 2012, Oct. 2012, < - http://www.cttc.es/resources/ - doc/120821-sensors2012-4396981770946977737.pdf>. - - [TASA-WCNC] - Accettura, N., Palattella, MR., Dohler, M., Grieco, LA., - and G. Boggia, "Standardized Power-Efficient and Internet- - Enabled Communication Stack for Capillary M2M Networks", - IEEE WCNC 2012, Apr. 2012, < http://www.cttc.es/resources/ - doc/120109-1569521283-submitted-58230.pdf>. - [palattella12standardized] Palattella, MR., Accettura, N., Vilajosana, X., Watteyne, T., Grieco, LA., Boggia, G., and M. Dohler, "Standardized Protocol Stack For The Internet Of (Important) Things", IEEE Communications Surveys and Tutorials 2012, Dec. 2012, < http://www.cttc.es/resources/doc/121025- completestackforiot-clean-4818610916636121981.pdf>. - [PANA] Kanda, M., Ohba, Y., Das, S., and S. Chasko, "PANA - applicability in constrained environments", Febr. 2012, . - Appendix A. TSCH Protocol Highlights This appendix gives an overview of the key features of the IEEE802.15.4e Timeslotted Channel Hopping (TSCH) amendment. It makes no attempt at repeating the standard, but rather focuses on the following: o Concepts which are sufficiently different from traditional IEEE802.15.4 networking that they may need to be defined and presented precisely. @@ -833,21 +734,22 @@ schedule for that scheduled cell, and the same ASN counter, they compute the same frequency. At the next iteration (cycle) of the slotframe, however, while the channelOffset is the same, the ASN has changed, resulting in the computation of a different frequency. This results in "channel hopping": even with a static schedule, pairs of neighbors "hop" between the different frequencies when communicating. A way of ensuring communication happens on all available frequencies is to set the number of timeslots in a slotframe to a prime number. Channel hopping is a technique known to - efficiently combat multi-path fading and external interference. + efficiently combat multi-path fading and external interference + [watteyne09reliability]. A.8. Time Synchronization Because of the slotted nature of communication in a TSCH network, nodes have to maintain tight synchronization. All nodes are assumed to be equipped with clocks to keep track of time. Yet, because clocks in different nodes drift with respect to one another, neighbor nodes need to periodically re-synchronize. Each node needs to periodically synchronize its network clock to