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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6TiSCH MR. Palattella, Ed. 3 Internet-Draft SnT/Univ. of Luxembourg 4 Intended status: Informational P. Thubert 5 Expires: August 17, 2014 cisco 6 T. Watteyne 7 Linear Technology / Dust Networks 8 Q. Wang 9 Univ. of Sci. and Tech. Beijing 10 February 13, 2014 12 Terminology in IPv6 over the TSCH mode of IEEE 802.15.4e 13 draft-ietf-6tisch-terminology-01 15 Abstract 17 6TiSCH 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 August 17, 2014. 48 Copyright Notice 50 Copyright (c) 2014 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 . . . . . . . . . . . . . . . . . . . . . 9 68 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 69 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 70 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 71 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 72 6.2. Informative References . . . . . . . . . . . . . . . . . 10 73 6.3. External Informative References . . . . . . . . . . . . . 11 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 76 1. Introduction 78 A new breed of Time Sensitive Networks is being developed 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 in industrial 82 automation or in-vehicle sensors and actuators. 84 At IEEE802.1, the "Audio/Video Task Group", was renamed 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 capabilities to the point that a packet 89 that 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] and use terms from RFC 100 6550 [RFC6550] and RFC 6552 [RFC6552], which are all included here by 101 reference. 103 The draft does not reuse terms from IEEE802.15.4e such as "path" or 104 "link" which bear a meaning that is quite different from classical 105 IETF parlance. 107 This document adds the following terms: 109 6TiSCH: IPv6 over the Timeslotted Channel Hopping (TSCH) mode of 110 IEEE 802.15.4e. It defines a set of IETF sublayers and 111 protocols (in particular, for setting up a schedule with 112 a centralized or distributed approach, managing the 113 resource allocation), as well as the architecture to bind 114 them together, for use in IPv6 TSCH based networks. 116 6F: IPv6 Forwarding. One of the three forwarding model 117 supported by 6TiSCH. Packets are routed at layer 3, 118 where QoS and RED operations are expected to prioritize 119 flows with differentiated services. 121 6top: 6top is the adaptation layer between TSCH and upper 122 layers like 6LoWPAN and RPL. It is defined in 123 [I-D.draft-wang-6tsch-6top]. 125 6top Data Convey Model: Model describing how the 6top adaptation 126 layer feeds the data flow coming from upper layers into 127 TSCH. It is composed by an I-MUX module, a MUX module, a 128 set of priority queues, and a PDU (Payload Data Unit). 130 ASN: Absolute Slot Number, the timeslot counter, incremented 131 by one at each timeslot. It is wide enough to not roll 132 over in practice. See 133 [I-D.watteyne-6tsch-tsch-lln-context]. 135 Blacklist: Set of frequencies which should not be used for 136 communication. 138 BBR: Backbone Router. In the 6TiSCH architecture, it is an 139 LBR and also a NEAR. It performs ND proxy operations 140 between registered devices and classical ND devices that 141 are located over the backbone. 143 Broadcast cell: A scheduled cell whose neighbor MAC address is set 144 to the broadcast address. 146 Bundle: A group of equivalent scheduled cells, i.e. cells 147 identified by different [slotOffset, channelOffset], 148 which are scheduled for a same purpose, with the same 149 neighbor, with the same flags, and the same slotframe. 150 The size of the bundle refers to the number of cells it 151 contains. Given the length of the slotframe, the size of 152 the bundle translates directly into bandwidth, either 153 logical, or physical. 155 Cell: A single element in the TSCH schedule, identified by a 156 slotOffset, a channelOffset, a slotframeHandle. A cell 157 can be scheduled or unscheduled. 159 ChannelOffset: Identifies a row in the TSCH slotframe. The number 160 of available channelOffsets is equal to the number of 161 available frequencies. The channelOffset translates into 162 a frequency when the communication takes place, resulting 163 in channel hopping, as detailed in 164 [I-D.watteyne-6tsch-tsch-lln-context]. 166 Channel distribution/usage (CDU) matrix: : Matrix of height equal to 167 the number of available channels (i.e, ChannelOffsets), 168 representing the spectrum(channel) distribution among the 169 different (RPL parent) nodes in the networks. Every 170 single element of the matrix belongs to a specific chunk. 171 It has to be noticed that such matrix, even though it 172 includes all the cells grouped in chunks, belonging to 173 different slotframes, is different from the TSCH 174 schedule. 176 Chunk: A well-known list of cells, well-distributed in time and 177 frequency, within a slotframe; a chunk represents a 178 portion of a slotframe that is globally known by all the 179 nodes in the network, but it can be managed separately by 180 a single node. A node can have multiple chunks, and use 181 them according to a specific policy. Chunks may overlap. 182 They can be pre-programmed, or can be computed by an 183 external entity at the network bootstrap. 185 Chunk ownership appropriation: The process by which an individual 186 node obtains a chunk to manage based on peer-to-peer 187 interaction with its neighbors. 189 Chunk ownership delegation: The process by which an individual node 190 obtains a chunk to manage based on point-to-point 191 interaction with an external entity. 193 Communication Paradigm: It is Associated with the Information Model 194 [RFC3444] of the state that is exchanged, and indicates: 195 the location of that state (e.g., centralized vs. 196 distributed, RESTful, etc.), the numbers of parties 197 (e.g., P2P vs. P2MP) and the relationship between parties 198 (e.g., master/slave vs. peers) at a high level of 199 protocol abstraction. Layer 5 client/server REST is a 200 typical communication paradigm, but industrial protocols 201 also use publish/subscribe which is P2MP and source/sink 202 which is MP2MP and primarily used for alarms and alerts 203 at the application layer. At layer 3, basic flooding, 204 P2P synchronization and path-marking (RSVP-like) are 205 commonly used paradigms, whereas at layer 2, master/slave 206 polling and peer-to-peer forwarding are classical 207 examples. 209 Dedicated Cell: A cell that is reserved for a given node to transmit 210 to a specific neighbor. 212 Distributed cell reservation: A reservation of a cell done by one or 213 more in-network entities (typically a connection 214 endpoint). 216 Distributed track reservation: A reservation of a track done by one 217 or more in-network entities (typically a connection 218 endpoint). 220 EB: Enhanced Beacon frame used by an advertising node to 221 announce the presence of the network. It contains 222 information about the timeslot length, the current ASN 223 value, the slotframes and timeslots the beaconing mote is 224 listening on, and a 1-byte join priority (i.e., number of 225 hops separating the node sending the EB, and the PAN 226 coordinator). 228 FF: 6LoWPAN Fragment Forwarding. It is one of the three 229 forwarding model supported by 6TiSCH. The 6LoWPAN 230 Fragment is used as a label for switching at the 6LoWPAN 231 sublayer, as defined in 232 [I-D.thubert-roll-forwarding-frags]. 234 GMPLS: Generalized Multi-Protocol Label Switching, a 2.5 layer 235 service that is used to forward packets based on the 236 concept of generalized labels. 238 Hard Cell: A scheduled cell which the 6top sublayer cannot 239 reallocate. See [I-D.draft-wang-6tsch-6top]. 241 Hopping Sequence: Sequence of frequencies, identified by a 242 Hopping_Sequence_ID, used for channel hopping, when 243 translating the channel offset value into a frequency 244 (i.e., PHY channel). See 245 [I-D.watteyne-6tsch-tsch-lln-context]. 247 IE: Information Elements, a list of Type-Length-Value 248 containers placed at the end of the MAC header, used to 249 pass data between layers or devices. A small number of 250 types are defined by TSCH, but a range of types is 251 available for extensions, and thus, is exploitable by 252 6TiSCH. See [I-D.watteyne-6tsch-tsch-lln-context]. 254 I-MUX module: Inverse-Multiplexer, a classifier that receives 255 6LoWPAN frames and places them into priority queues. 257 Interaction Model: It is a particular way of implementing a 258 communication paradigm. Defined at a lower level of 259 abstraction, it includes protocol-specific details such 260 as a particular method (e.g., a REST GET) and a Data 261 Model for the state to be exchanged. 263 KMP: Key Managment Protocol. 265 LBR: LLN Border Router. It is an LLN device, usually powered, 266 that acts as a Border Router to the outside within the 267 6TiSCH architecture. 269 Link: A communication facility or medium over which nodes can 270 communicate at the link layer, i.e., the layer 271 immediately below IP. Thus, the IETF parlance for the 272 term "Link" is adopted, as opposed to the incompatible 273 IEEE802.15.4e terminology. In the context of the 6TiSCH 274 architecture, which applies to Low Power Lossy Networks 275 (LLNs), an IPv6 subnet is usually not congruent to a 276 single link and techniques such as IPv6 Neighbor 277 Discovery Proxying and Routing Over LLNs are required to 278 achieve reachability within the multilink subnet. A link 279 is distinct from a track. In fact, link local addresses 280 are not expected to be used over a track for end to end 281 communication. Finally, from the Layer 3 perspective 282 (where the inner complexities of TSCH operations are 283 hidden to enable classical IP routing and Forwarding), a 284 single radio interface may be seen as a number of Links 285 with different capabilities for unicast or multicast 286 services. 288 Logical Cell: A cell that corresponds to granted bandwidth but is 289 only lazily associated to a physical cell, based on 290 usage. 292 MAC: Medium Access Control. 294 MUX module: Multiplexer, the entity that dequeues frames from 295 priority queues and associates them to a cell for 296 transmission. 298 NEAR: Energy Aware Default Router, as defined in 299 [I-D.chakrabarti-nordmark-6man-efficient-nd]. 301 NME: Network Management Entity, the entity in the network 302 managing cells and other device resources. It may 303 cooperate with the PCE. It interacts with LLN nodes 304 through the backbone router. 306 PANA: Protocol for carrying Authentication for Network Access, 307 as defined in [RFC5191] . It is the protocol used in the 308 6TiSCH architecture for handling authentication during 309 the join process. 311 PCE: Path Computation Element, the entity in the network which 312 is responsible for building and maintaining the TSCH 313 schedule, when centralized scheduling is used. 315 PCE cell reservation: The reservation of a cell done by the PCE. 317 PCE track reservation: The reservation of a track done by the PCE. 319 QoS: Quality of Service. 321 (to) reallocate a cell: The action operated by the 6top sublayer of 322 changing the slotOffset and/or channelOffset of a soft 323 cell. 325 SA: Security Association. 327 (to) Schedule a cell: The action of turning an unscheduled cell into 328 a scheduled cell. 330 Scheduled cell: A cell which is assigned a neighbor MAC address 331 (broadcast address is also possible), and one or more of 332 the following flags: TX, RX, shared, timeskeeping. A 333 scheduled cell can be used by the IEEE802.15.4e TSCH 334 implementation to communicate. A scheduled cell can be a 335 hard cell or a soft cell. 337 Shared Cell: A cell that is used by more than one transmitter nodes 338 at the same time and on the same channelOffset. Only 339 cells with TX flag can be marked as "shared". A backoff 340 algorithm is used to resolve contention. 342 SlotOffset: Identifies a column in the TSCH schedule, i.e., the 343 number of timeslots since the beginning of the current 344 iteration of the slotframe. 346 Slotframe: A MAC-level abstraction that is internal to the node and 347 contains a series of timeslots of equal length and 348 priority. It is characterized by a slotframe_ID, and a 349 slotframe_size. Multiple slotframes can coexist in a 350 node's schedule, i.e., a node can have multiple 351 activities scheduled in different slotframes, based on 352 the priority of its packets/traffic flows. The timeslots 353 in the Slotframe are indexed by the SlotOffset; the first 354 timeslot is at SlotOffset 0. 356 Soft Cell: A scheduled cell which the 6top sublayer can reallocate, 357 as described in [I-D.draft-wang-6tsch-6top]. 359 TF: Track Forwarding. It is the simplest and fastest 360 forwarding model supported by 6TiSCH. It is a G-MPLS- 361 like forwarding model. The input cell characterises the 362 flow and indicates the output cell. 364 Timeslot: A basic communication unit in TSCH which allows a 365 transmitter node to send a frame to a receiver neighbor, 366 and that receiver neighbor to optionally send back an 367 acknowledgment. The length of the timeslot determines 368 the maximum size of the frame that can be exchanged. 370 Time Source Neighbor: A neighbor a node uses as its time reference, 371 and to which it needs to keep its clock synchronized. A 372 node can have one or more time source neighbors. 374 Track: A determined sequence of cells along a multi-hop path. 375 It is typically the result of a reservation. The node 376 that initializes the process for establishing a track is 377 the owner of the track. The latter assigns a unique 378 identifier to the track, called TrackID. 380 TrackID: Unique identifier of a track, assigned by the owner of 381 the track. 383 TSCH: Time Slotted Channel Hopping, a medium access mode of the 384 [IEEE802154e] standard which uses time synchronization to 385 achieve ultra low-power operation and channel hopping to 386 enable high reliability. 388 TSCH Schedule: A matrix of cells, each cell indexed by a slotOffset 389 and a channelOffset. The slotframe size (the "width" of 390 the matrix) is the number of timeslots it contains. The 391 number of channelOffset values (the "height" of the 392 matrix) is equal to the number of available frequencies. 393 The TSCH schedule contains all the scheduled cells from 394 all slotframes and is sufficient to qualify the 395 communication in the TSCH network. 397 unscheduled cell: A cell which is not used by the IEEE802.15.4e TSCH 398 implementation. 400 3. IANA Considerations 402 This specification does not require IANA action. 404 4. Security Considerations 406 This specification is not found to introduce new security threat. 408 5. Acknowledgements 410 Thanks to the IoT6 European Project (STREP) of the 7th Framework 411 Program (Grant 288445). 413 6. References 415 6.1. Normative References 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", BCP 14, RFC 2119, March 1997. 420 [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between 421 Information Models and Data Models", RFC 3444, January 422 2003. 424 [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. 425 Yegin, "Protocol for Carrying Authentication for Network 426 Access (PANA)", RFC 5191, May 2008. 428 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 429 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 430 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 431 Lossy Networks", RFC 6550, March 2012. 433 [RFC6552] Thubert, P., "Objective Function Zero for the Routing 434 Protocol for Low-Power and Lossy Networks (RPL)", RFC 435 6552, March 2012. 437 6.2. Informative References 439 [I-D.chakrabarti-nordmark-6man-efficient-nd] 440 Chakrabarti, S., Nordmark, E., Thubert, P., and M. 441 Wasserman, "Wired and Wireless IPv6 Neighbor Discovery 442 Optimizations", draft-chakrabarti-nordmark-6man-efficient- 443 nd-04 (work in progress), October 2013. 445 [I-D.draft-sudhaakar-6tisch-coap] 446 Sudhaakar, R., Ed. and P. Zand, "6TiSCH Data Model for 447 CoAP-00 (work in progress)", October 2013. 449 [I-D.draft-wang-6tsch-6top] 450 Wang, Q., Ed., Vilajosana, X., and T. Watteyne, "6TiSCH 451 Operation Sublayer (6top). draft-wang-6tisch-6top-00 (work 452 in progress)", October 2013. 454 [I-D.ietf-roll-terminology] 455 Vasseur, J., "Terms used in Routing for Low power And 456 Lossy Networks", draft-ietf-roll-terminology-13 (work in 457 progress), October 2013. 459 [I-D.ohba-6tsch-security] 460 Chasko, S., Das, S., Lopez, R., Ohba, Y., Thubert, P., and 461 A. Yegin, "Security Framework and Key Management Protocol 462 Requirements for 6TSCH", draft-ohba-6tsch-security-01 463 (work in progress), July 2013. 465 [I-D.thubert-6tisch-architecture] 466 Thubert, P., Watteyne, T., and R. Assimiti, "An 467 Architecture for IPv6 over the TSCH mode of IEEE 468 802.15.4e", draft-thubert-6tisch-architecture-01 (work in 469 progress), October 2013. 471 [I-D.thubert-roll-forwarding-frags] 472 Thubert, P. and J. Hui, "LLN Fragment Forwarding and 473 Recovery", draft-thubert-roll-forwarding-frags-02 (work in 474 progress), September 2013. 476 [I-D.vilajosana-6tisch-minimal] 477 Vilajosana, X. and K. Pister, "Minimal 6TiSCH 478 Configuration", draft-vilajosana-6tisch-minimal-00 (work 479 in progress), October 2013. 481 [I-D.watteyne-6tsch-tsch-lln-context] 482 Watteyne, T., Palattella, M., and L. Grieco, "Using 483 IEEE802.15.4e TSCH in an LLN context: Overview, Problem 484 Statement and Goals", draft-watteyne-6tsch-tsch-lln- 485 context-02 (work in progress), May 2013. 487 6.3. External Informative References 489 [IEEE802154e] 490 IEEE standard for Information Technology, "IEEE std. 491 802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area 492 Networks (LR-WPANs) Amendament 1: MAC sublayer", April 493 2012. 495 Authors' Addresses 497 Maria Rita Palattella (editor) 498 University of Luxembourg 499 Interdisciplinary Centre for Security, Reliability and Trust 500 4, rue Alphonse Weicker 501 Luxembourg L-2721 502 LUXEMBOURG 504 Phone: (+352) 46 66 44 5841 505 Email: maria-rita.palattella@uni.lu 507 Pascal Thubert 508 Cisco Systems, Inc 509 Village d'Entreprises Green Side 510 400, Avenue de Roumanille 511 Batiment T3 512 Biot - Sophia Antipolis 06410 513 FRANCE 515 Phone: +33 497 23 26 34 516 Email: pthubert@cisco.com 518 Thomas Watteyne 519 Linear Technology / Dust Networks 520 30695 Huntwood Avenue 521 Hayward, CA 94544 522 USA 524 Phone: +1 (510) 400-2978 525 Email: twatteyne@linear.com 526 Qin Wang 527 Univ. of Sci. and Tech. Beijing 528 30 Xueyuan Road 529 Beijing, Hebei 100083 530 China 532 Phone: +86 (10) 6233 4781 533 Email: wangqin@ies.ustb.edu.cn