6TiSCH MR. Palattella, Ed. Internet-Draft LIST Intended status: Informational P. Thubert Expires: September 3, 2018 cisco T. Watteyne Analog Devices Q. Wang Univ. of Sci. and Tech. Beijing March 2, 2018 Terms Used in IPv6 over the TSCH mode of IEEE 802.15.4e draft-ietf-6tisch-terminology-10 Abstract This document provides a glossary of terminology used in IPv6 over the TSCH mode of IEEE 802.15.4e (6TiSCH). This document extends existing terminology documents for Low-power and Lossy 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 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 3, 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 Palattella, et al. Expires September 3, 2018 [Page 1] Internet-Draft 6TiSCH Terminology March 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 4. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Normative References . . . . . . . . . . . . . . . . . . 7 4.2. Informative References . . . . . . . . . . . . . . . . . 8 4.3. External Informative References . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction The IEEE802.15.4 Medium Access Control (MAC) has evolved with the Time Slotted Channel Hopping (TSCH) mode for industrial-type applications. This document provides additional terminology elements to cover terms that are new to the context of TSCH wireless networks and other deterministic networks. 2. Terminology The draft extends [RFC7102] and use terms from [RFC6550] and [RFC6552], which are all included here by reference. The draft does not reuse terms from IEEE802.15.4 such as "path" or "link" which bear a meaning that is quite different from classical IETF parlance. This document adds the following terms: 6TiSCH (IPv6 over the TSCH mode of IEEE 802.15.4e): It defines the 6top sublayer, a set of protocols for setting up a TSCH schedule in distributed approach, and a security solution. 6top (6TiSCH Operation Sublayer): The next highest layer of the IEEE802.15.4 TSCH medium access control layer. It implements and terminates 6P, and contains at least one SF. 6P (6top Protocol): Allows neighbor nodes to communicate to add/ delete cells to one another in their TSCH schedule. Palattella, et al. Expires September 3, 2018 [Page 2] Internet-Draft 6TiSCH Terminology March 2018 6P Transaction: Part of 6P, the action of two neighbors exchanging a 6P request message and the corresponding 6P response message. ASN (Absolute Slot Number): The total number of timeslots that have elapsed since the PAN coordinator has started the TSCH network. Incremented by one at each timeslot. It is wide enough to not roll over in practice. BBR (Backbone Router): An LBR and also a IPv6 ND-efficiency-aware Router (NEAR) [I-D.chakrabarti-nordmark-6man-efficient-nd]. Performs ND proxy operations between registered devices and classical ND devices that are located on the backbone. blacklist of frequencies: A set of frequencies which should not be used for communication. broadcast cell: A scheduled cell used for broadcast transmission. bundle: A group of equivalent scheduled cells, i.e. cells identified by different [slotOffset, channelOffset], which are scheduled for a same purpose, with the same neighbor, with the same flags, and the same slotframe. The size of the bundle refers to the number of cells it contains. For a given slotframe length, the size of the bundle translates directly into bandwidth. A bundle is a local abstraction that represents a half-duplex link for either sending or receiving, with bandwidth that amounts to the sum of the cells in the bundle. CCA (Clear Channel Assessment): Mechanism defined in [IEEE802154-2015], section 6.2.5.2. In a TSCH network, CCA can be used to detect other radio networks in vicinity. Nodes listen the channel before sending, to detect other ongoing transmissions. Because the network is synchronized, CCA cannot be used to detect colliding transmission within the same network. cell: A single element in the TSCH schedule, identified by a slotOffset, a channelOffset, a slotframeHandle. A cell can be scheduled or unscheduled. centralized cell reservation: A reservation of a cell done by a centralized entity (e.g., a PCE) in the network. centralized track reservation: A reservation of a track done by a centralized entity (e.g., a PCE) in the network. Palattella, et al. Expires September 3, 2018 [Page 3] Internet-Draft 6TiSCH Terminology March 2018 Channel Distribution/Usage (CDU) matrix: : Matrix of cells (i,j) representing the spectrum (channel) distribution among the different nodes in the 6TiSCH network. The CDU matrix has width in timeslots, equal to the period of the network scheduling operation, and height equal to the number of available channels. Every cell (i,j) in the CDU, identified by (slotOffset, channelOffset), belongs to a specific chunk. It has to be noticed that such a matrix which includes all the cells grouped in chunks, belonging to different slotframes, is different from the TSCH schedule. channelOffset: Identifies a row in the TSCH schedule. The number of available channelOffset values is equal to the number of available frequencies. The channelOffset translates into a frequency when the communication takes place, resulting in channel hopping. chunk: A well-known list of cells, distributed in time and frequency, within a CDU matrix. A chunk represents a portion of a CDU matrix. The partition of the CDU matrix in chunks is globally known by all the nodes in the network to support the appropriation process, which is a negotiation between nodes within an interference domain. A node that manages to appropriate a chunk gets to decide which transmissions will occur over the cells in the chunk within its interference domain (i.e., a parent node will decide when the cells within the appropriated chunk are used and by which node, among its children. dedicated cell: A cell that is reserved for a given node to transmit to a specific neighbor. deterministic network: The generic concept of deterministic network is defined in [I-D.ietf-detnet-architecture]. When applied to 6TiSCH, it refers to the reservation of tracks which guarantee an end-to-end latency and optimize the PDR for well-characterized flows. distributed cell reservation: A reservation of a cell done by one or more in-network entities. distributed track reservation: A reservation of a track done by one or more in-network entities. EB (Enhanced Beacon): A special frame defined used by a node, including the JP, to announce the presence of the Palattella, et al. Expires September 3, 2018 [Page 4] Internet-Draft 6TiSCH Terminology March 2018 network. It contains enough information for a pledge to synchronize to the network. hard cell: A scheduled cell which the 6top sublayer cannot relocate. hopping sequence: Ordered sequence of frequencies, identified by a Hopping_Sequence_ID, used for channel hopping when translating the channel offset value into a frequency. IE (Information Element): Type-Length-Value containers placed at the end of the MAC header, used to pass data between layers or devices. Some IE identifiers are managed by the IEEE [IEEE802154-2015]. Some IE identifiers are managed by the IETF [I-D.kivinen-802-15-ie]. join process: The overall process that includes the discovery of the network by pledge(s) and the execution of the join protocol. join protocol: The protocol that allows the pledge to join the network. The join protocol encompasses authentication, authorization and parameter distribution. The join protocol is executed between the pledge and the JRC. joined node: The new device, after having completed the join process, often just called a node. JP (Join Proxy): Node already part of the 6TiSCH network that serves as a relay to provide connectivity between the pledge and the JRC. The JP announces the presence of the network by regularly sending EB frames. JRC (Join Registrar/Coordinator): Central entity responsible for the authentication, authorization and configuration of the pledge. LBR: Low-power Lossy Network (LLN) Border Router. It is an LLN device, usually powered, that acts as a Border Router to the outside within the 6TiSCH architecture. link: A communication facility or medium over which nodes can communicate at the link layer, the layer immediately below IP. The IETF parlance for the term "Link" is adopted, as opposed to the IEEE802.15.4 terminology. pledge: A new device that attempts to join a 6TiSCH network. Palattella, et al. Expires September 3, 2018 [Page 5] Internet-Draft 6TiSCH Terminology March 2018 (to) relocate a cell: The action operated by the 6top sublayer of changing the slotOffset and/or channelOffset of a soft cell. (to) schedule a cell: The action of turning an unscheduled cell into a scheduled cell. scheduled cell: A cell which is assigned a neighbor MAC address (broadcast address is also possible), and one or more of the following flags: TX, RX, shared, timeskeeping. A scheduled cell can be used by the IEEE802.15.4 TSCH implementation to communicate. A scheduled cell can either be a hard or a soft cell. SF (6top Scheduling Function): The cell management entity that adds or deletes cells dynamically based on application networking requirements. The cell negotiation with a neighbor is done using 6P. SFID (6top Scheduling Function Identifier): A 4-bit field identifying an SF. shared cell: A cell marked with both the "TX" and "shared" flags. This cell can be used by more than one transmitter node. A back-off algorithm is used to resolve contention. slotframe: A collection of timeslots repeating in time, analogous to a superframe in that it defines periods of communication opportunities. It is characterized by a slotframe_ID, and a slotframe_size. Multiple slotframes can coexist in a node's schedule, i.e., a node can have multiple activities scheduled in different slotframes, based on the priority of its packets/traffic flows. The timeslots in the Slotframe are indexed by the SlotOffset; the first timeslot is at SlotOffset 0. slotOffset: A column in the TSCH schedule, i.e. the number of timeslots since the beginning of the current iteration of the slotframe. soft cell: A scheduled cell which the 6top sublayer can relocate. time source neighbor: A neighbor that a node uses as its time reference, and to which it needs to keep its clock synchronized. timeslot: A basic communication unit in TSCH which allows a transmitter node to send a frame to a receiver neighbor, Palattella, et al. Expires September 3, 2018 [Page 6] Internet-Draft 6TiSCH Terminology March 2018 and that receiver neighbor to optionally send back an acknowledgment. track: A determined sequence of cells along a multi-hop path. It is typically the result of a track reservation. The node that initializes the process of establishing a track is the owner of the track. The latter assigns a unique identifier to the track, called TrackID. TrackID: Unique identifier of a track. TSCH (6top Scheduling Function Identifier): A medium access mode of the [IEEE802154-2015] standard which uses time synchronization to achieve ultra low-power operation, and channel hopping to enable high reliability. TSCH Schedule: A matrix of cells, each cell indexed by a slotOffset and a channelOffset. The TSCH schedule contains all the scheduled cells from all slotframes and is sufficient to qualify the communication in the TSCH network. The number of channelOffset values (the "height" of the matrix) is equal to the number of available frequencies. Unscheduled Cell: A cell which is not used by the IEEE802.15.4 TSCH implementation. 3. Security Considerations Since this document specifies terminology and does not specify new procedures or protocols, it raises no new security issues. 4. References 4.1. Normative References [RFC6550] Winter, T., Ed., Thubert, P., Ed., 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, DOI 10.17487/RFC6550, March 2012, . [RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing Protocol for Low-Power and Lossy Networks (RPL)", RFC 6552, DOI 10.17487/RFC6552, March 2012, . Palattella, et al. Expires September 3, 2018 [Page 7] Internet-Draft 6TiSCH Terminology March 2018 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 2014, . 4.2. Informative References [I-D.chakrabarti-nordmark-6man-efficient-nd] Chakrabarti, S., Nordmark, E., Thubert, P., and M. Wasserman, "IPv6 Neighbor Discovery Optimizations for Wired and Wireless Networks", draft-chakrabarti-nordmark- 6man-efficient-nd-07 (work in progress), February 2015. [I-D.ietf-detnet-architecture] Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", draft-ietf- detnet-architecture-04 (work in progress), October 2017. [I-D.kivinen-802-15-ie] Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information Element for IETF", draft-kivinen-802-15-ie-06 (work in progress), March 2017. 4.3. External Informative References [IEEE802154-2015] IEEE standard for Information Technology, "IEEE Std 802.15.4-2015 Standard for Low-Rate Wireless Personal Area Networks (WPANs)", December 2015. Authors' Addresses Maria Rita Palattella (editor) Luxembourg Institute of Science and Technology Department 'Environmental Research and Innovation' (ERIN) 41, rue du Brill Belvaux L-4422 Luxembourg Phone: (+352) 275 888-5055 Email: mariarita.palattella@list.lu Palattella, et al. Expires September 3, 2018 [Page 8] Internet-Draft 6TiSCH Terminology March 2018 Pascal Thubert Cisco Systems, Inc Village d'Entreprises Green Side 400, Avenue de Roumanille Batiment T3 Biot - Sophia Antipolis 06410 France Phone: +33 497 23 26 34 Email: pthubert@cisco.com Thomas Watteyne Analog Devices 32990 Alvarado-Niles Road, Suite 910 Union City, CA 94587 USA Email: thomas.watteyne@analog.com Qin Wang Univ. of Sci. and Tech. Beijing 30 Xueyuan Road Beijing 100083 China Phone: +86 (10) 6233 4781 Email: wangqin@ies.ustb.edu.cn Palattella, et al. Expires September 3, 2018 [Page 9]