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


   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

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   This Internet-Draft will expire on September 3, 2018.

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   include Simplified BSD License text as described in Section 4.e of
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   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

   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

   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

   6P (6top Protocol):  Allows neighbor nodes to communicate to add/
               delete cells to one another in their TSCH schedule.

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   6P Transaction:  Part of 6P, the action of two neighbors exchanging a
               6P request message and the corresponding 6P response

   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  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.

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   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

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               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

   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

   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.

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   (to) relocate a cell:  The action operated by the 6top sublayer of
               changing the slotOffset and/or channelOffset of a soft

   (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

   timeslot:   A basic communication unit in TSCH which allows a
               transmitter node to send a frame to a receiver neighbor,

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               and that receiver neighbor to optionally send back an

   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

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,

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   [RFC7102]  Vasseur, JP., "Terms Used in Routing for Low-Power and
              Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
              2014, <https://www.rfc-editor.org/info/rfc7102>.

4.2.  Informative References

              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.

              Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", draft-ietf-
              detnet-architecture-04 (work in progress), October 2017.

              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

              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

   Phone: (+352) 275 888-5055
   Email: mariarita.palattella@list.lu

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   Pascal Thubert
   Cisco Systems, Inc
   Village d'Entreprises Green Side
   400, Avenue de Roumanille
   Batiment T3
   Biot - Sophia Antipolis  06410

   Phone: +33 497 23 26 34
   Email: pthubert@cisco.com

   Thomas Watteyne
   Analog Devices
   32990 Alvarado-Niles Road, Suite 910
   Union City, CA  94587

   Email: thomas.watteyne@analog.com

   Qin Wang
   Univ. of Sci. and Tech. Beijing
   30 Xueyuan Road
   Beijing  100083

   Phone: +86 (10) 6233 4781
   Email: wangqin@ies.ustb.edu.cn

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