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Palattella, Ed. 3 Internet-Draft SnT/Univ. of Luxembourg 4 Intended status: Informational P. Thubert 5 Expires: September 11, 2013 cisco 6 T. Watteyne 7 Linear Technology / Dust Networks 8 Q. Wang 9 Univ. of Sci. and Tech. Beijing 10 March 10, 2013 12 Terminology in IPv6 over Time Slotted Channel Hopping 13 draft-palattella-6tsch-terminology-00 15 Abstract 17 6TSCH proposes an architecture for an IPv6 multilink subnet that is 18 composed of a high speed powered backbone and a number of 19 IEEE802.15.4e TSCH wireless networks attached and synchronized by 20 backbone routers. This document extends existing terminology 21 documents available for Low-power and Lossy Networks to provide 22 additional terminology elements. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 28 "OPTIONAL" in this document are to be interpreted as described in RFC 29 2119 [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on September 11, 2013. 48 Copyright Notice 50 Copyright (c) 2013 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 68 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 69 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 70 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 71 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 72 6.2. Informative References . . . . . . . . . . . . . . . . . 6 73 6.3. External Informative References . . . . . . . . . . . . . 7 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 76 1. Introduction 78 A new breed of Time Sensitive Networks is being developped to enable 79 traffic that is highly sensitive to jitter and quite sensitive to 80 latency. Such traffic is not limited to voice and video, but also 81 includes command and control operations such as found in industrial 82 automation or in-vehicule sensors and actuators. 84 At IEEE802.1, the "Audio/Video Task Group", was rename TSN for Time 85 Sensitive Networking. The IEEE802.15.4 Medium Access Control (MAC) 86 has evolved with IEEE802.15.4e which provides in particular the Time 87 Slotted Channel Hopping (TSCH) mode for industrial-type applications. 88 Both provide Deterministic capabities to the point that a packet that 89 pertains to a certain flow crosses the network from node to node 90 following a very precise schedule, like a train leaves intermediate 91 stations at precise times along its path. 93 This document provides additional terminology elements to cover terms 94 that are new to the context of TSCH wireless networks and other 95 deterministic networks. 97 2. Terminology 99 The draft extends [I-D.ietf-roll-terminology] which is included here 100 by reference. 102 The draft does not reuse terms from IEEE802.15.4e such as "path" or 103 "link" which bear a meaning that is quite different from classical 104 IETF parlance. 106 This document adds the following terms: 108 6TSCH: Entity that sets up the schedule, controls the 109 connectivity graph of the network, and the resources 110 allocated to each scheduled cell in that connectivity 111 graph. It may be an adaptation layer, a distributed 112 reservation protocol, a centralized path computation 113 entity, or any combination thereof. 115 6tus: 6tus (pronounced "sixtus") is the adaptation layer 116 between TSCH and upper layers like 6LoWPAN and RPL. It 117 is defined in [I-D.draft-wang-6tsch-6tus]. 119 6tus Data Convey Model: Model describing how the 6tus adaptation 120 layer feeds the data flow coming from upper layers into 121 TSCH. It is composed by an I-MUX module, a MUX module, a 122 set of priority queues, and a PDU (Payload Data Unit). 124 ASN: Absolute Slot Number, the timeslot counter, incremented 125 by one at each timeslot. It is wide enough to not roll 126 over in practice. See 127 [I-D.watteyne-6tsch-tsch-lln-context]. 129 Blacklisting: Set of frequencies which should not be used for 130 communication. 132 Bundle: A group of equivalent scheduled cells, i.e. cells 133 identified by different (slotOffset, channelOffset), 134 which are scheduled for a same purpose, with the same 135 neighbor, with the same flags, and the same slotframe. 136 The size of the bundle refers to the number of cells it 137 contains. Given the length of the slotframe, the size of 138 the bundle translates directly into bandwidth, either 139 logical, or physical. 141 Cell: A single element in the TSCH schedule, identified by a 142 slotOffset and a channelOffset value. A cell can be 143 scheduled or unscheduled. During an unscheduled cell, 144 the node does not communicate. When a cell is scheduled, 145 it is assigned a MAC-layer slotframe identifier, a 146 neighbor MAC address (which can be the broadcast 147 address), and one or more of the following flags: TX, RX, 148 shared, timeskeeping, hard. A broadcast cell is an alias 149 for "a scheduled cell with neighbor address the broadcast 150 address". 152 ChannelOffset: Identifies a row in the TSCH schedule. The number of 153 available channelOffsets is equal to the number of 154 available frequencies. The channelOffset translates into 155 a frequency when the communication takes place, resulting 156 in channel hopping, as detailed in 157 [I-D.watteyne-6tsch-tsch-lln-context]. 159 Dedicated Cell: A cell that is reserved for a given node to transmit 160 to a specific neigbor. 162 Distributed cell reservation: A reservation of a cell done by one or 163 more in-network entities (typically a connection 164 endpoint). 166 Distributed track reservation: A reservation of a track done by one 167 or more in-network entities (typically a connection 168 endpoint). 170 EB: Enhanced Beacon frame used by an avertising node to 171 announce the presence of the network. It contains 172 information about timeslot length, current ASN value, 173 slotframes and timeslots the beaconing mote is listening 174 on, and a 1-byte join priority (i.e., number of hops 175 separating the node sending the EB, and the PAN 176 coordinator). 178 GMPLS: Generalized Multi-Protocol Label Switching, a 2.5 layer 179 service that is used to forward packets based on the 180 concept of generalized labels. 182 Hard Cell: A scheduled cell that is locked, i.e., it cannot be moved 183 by 6tus in the schedule. See 184 [I-D.draft-wang-6tsch-6tus]. 186 IE: Information Elements, a list of Type-Length-Value 187 containers placed at the end of the MAC header, used to 188 pass data between layers or devices. A small number of 189 types are defined by TSCH, but a range of types is 190 available for extensions, and thus, is exploitable by 191 6TSCH. See [I-D.watteyne-6tsch-tsch-lln-context]. 193 I-MUX module: Inverse-Multiplexer, a classifier that receives 194 6LoWPAN frames and places them into priority queues. 196 Logical Cell: A cell that correspond to granted bandwidth but is 197 only lazily associated to a physical cell, based on 198 usage. 200 MUX module: Multiplexer, the entity that dequeues frames from 201 priority queues and associates them to a cell for 202 transmission. 204 PCE: Path Computation Entity, the entity in the network which 205 is responsible for building and maintaining the TSCH 206 schedule, when centralized scheduling is used. 208 PCE cell reservation: The reservation of a cell done by the PCE. 210 PCE track reservation: The reservation of a track done by the PCE. 212 Provisioned Cell: A soft cell which provides redundancy above the 213 required bandwidth to ensure some QoS level. 215 QoS: Quality of Service. 217 Shared Cell: A cell that is used by transmitted nodes at the same 218 time and on the same channelOffset. Only cells with TX 219 flag can be marked as "shared". A backoff algorithm is 220 used to resolve contention. 222 SlotOffset: Identifies a column in the TSCH schedule, i.e. the 223 number of timeslots since the beginning of the current 224 iteration of the slotframe. 226 Slotframe: A MAC-level abstraction that is internal to the node and 227 contains a series of timeslots of equal length and 228 priority. Multiple slotframes can coexist in a node's 229 schedule, i.e., a node can have multiple activities 230 scheduled in different slotframes, based on the priority 231 of its packets/traffic flows. The timeslots in the 232 Slotframe are indexed by the SlotOffset; the first 233 timeslot is at SlotOffset 0. 235 Soft Cell: A scheduled cell that is not locked, i.e., it may be 236 moved in the schedule within a same slotframe by 6tus 237 [I-D.draft-wang-6tsch-6tus]. 239 Timeslot: A basic communication unit in TSCH which allows a 240 transmitter node to send a frame to a receiver neighbor, 241 and that receiver neighbor to optionally send back an 242 acknowledgment. The length of the timeslot determines 243 the maximum size of the frame and the number of 244 acknowledgements (in case multiple are used, e.g., 245 duocast), that can be exchanged. 247 Time Source Neighbor: A neighbor a node uses as its time reference, 248 and to which it needs to keep its clock synchronized. A 249 node can have one or more time source neighbors. 251 Track: A determined sequence of cells along a multi-hop path. 252 This is typically the result of a reservation. 254 TSCH: Time Slotted Channel Hopping, a medium access mode of the 255 [IEEE802154e] standard which uses time synchronization to 256 achieve ultra low-power operation and channel hopping to 257 enable high reliability. 259 TSCH Schedule: A matrix of cells, each cells indexed by a slotOffset 260 and a channelOffset. The slotframe size (the "width" of 261 the matrix) is the number of timeslots it contains. The 262 number of channelOffset values (the "height" of the 263 matrix) is equal to the number of available frequencies. 264 The TSCH schedule contains all the scheduled cells from 265 all slotframes and is sufficient to qualify the 266 communication in the TSCH network. 268 3. IANA Considerations 270 This specification does not require IANA action. 272 4. Security Considerations 274 This specification is not found to introduce new security threat. 276 5. Acknowledgements 278 6. References 280 6.1. Normative References 282 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 283 Requirement Levels", BCP 14, RFC 2119, March 1997. 285 6.2. Informative References 287 [I-D.draft-thubert-6tsch-architecture] 288 Thubert, P., Ed., Assimiti, R., and T. Watteyne, "An 289 Architecture for IPv6 over Time Synchronized Channel 290 Hopping. draft-thubert-6tsch-architecture-00 (work in 291 progress) ", March 2013. 293 [I-D.draft-wang-6tsch-6tus] 294 Wang, Q., Ed., Vilajosana, X., and T. Watteyne, "6tus 295 Adaptation Layer Specification. draft-wang-6tsch-6tus-00 296 (work in progress) ", March 2013. 298 [I-D.ietf-roll-terminology] 299 Vasseur, J., "Terminology in Low power And Lossy 300 Networks", draft-ietf-roll-terminology-11 (work in 301 progress), February 2013. 303 [I-D.watteyne-6tsch-tsch-lln-context] 304 Watteyne, T., "Using IEEE802.15.4e TSCH in an LLN context: 305 Overview, Problem Statement and Goals", draft-watteyne- 306 6tsch-tsch-lln-context-01 (work in progress), February 307 2013. 309 6.3. External Informative References 311 [IEEE802154e] 312 IEEE standard for Information Technology, "IEEE std. 313 802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area 314 Networks (LR-WPANs) Amendament 1: MAC sublayer", April 315 2012. 317 Authors' Addresses 319 Maria Rita Palattella (editor) 320 University of Luxembourg 321 Interdisciplinary Centre for Security, Reliability and Trust 322 4, rue Alphonse Weicker 323 Luxembourg L-2721 324 LUXEMBOURG 326 Phone: (+352) 46 66 44 5841 327 Email: maria-rita.palattella@uni.lu 328 Pascal Thubert 329 Cisco Systems, Inc 330 Village d'Entreprises Green Side 331 400, Avenue de Roumanille 332 Batiment T3 333 Biot - Sophia Antipolis 06410 334 FRANCE 336 Phone: +33 497 23 26 34 337 Email: pthubert@cisco.com 339 Thomas Watteyne 340 Linear Technology / Dust Networks 341 30695 Huntwood Avenue 342 Hayward, CA 94544 343 USA 345 Phone: +1 (510) 400-2978 346 Email: twatteyne@linear.com 348 Qin Wang 349 Univ. of Sci. and Tech. Beijing 350 30 Xueyuan Road 351 Beijing, Hebei 100083 352 China 354 Phone: +86 (10) 6233 4781 355 Email: wangqin@ies.ustb.edu.cn