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Hong 3 Internet-Draft ETRI 4 Intended status: Informational C. Gomez 5 Expires: January 1, 2019 UPC 6 Y-H. Choi 7 ETRI 8 AR. Sangi 9 Huaiyin Institute of Technology 10 T. Aanstoot 11 Modio AB 12 S. Chakrabarti 13 June 30, 2018 15 IPv6 over Constrained Node Networks (6lo) Applicability & Use cases 16 draft-ietf-6lo-use-cases-05 18 Abstract 20 This document describes the applicability of IPv6 over constrained 21 node networks (6lo) and provides practical deployment examples. In 22 addition to IEEE 802.15.4, various link layer technologies such as 23 ITU-T G.9959 (Z-Wave), BLE, DECT-ULE, MS/TP, NFC, PLC (IEEE 1901.2), 24 and IEEE 802.15.4e (6tisch) are used as examples. The document 25 targets an audience who like to understand and evaluate running end- 26 to-end IPv6 over the constrained node networks connecting devices to 27 each other or to other devices on the Internet (e.g. cloud 28 infrastructure). 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on January 1, 2019. 47 Copyright Notice 49 Copyright (c) 2018 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4 66 3. 6lo Link layer technologies and possible candidates . . . . . 4 67 3.1. ITU-T G.9959 (specified) . . . . . . . . . . . . . . . . 4 68 3.2. Bluetooth LE (specified) . . . . . . . . . . . . . . . . 4 69 3.3. DECT-ULE (specified) . . . . . . . . . . . . . . . . . . 5 70 3.4. MS/TP (specified) . . . . . . . . . . . . . . . . . . . . 5 71 3.5. NFC (specified) . . . . . . . . . . . . . . . . . . . . . 6 72 3.6. PLC (specified) . . . . . . . . . . . . . . . . . . . . . 7 73 3.7. IEEE 802.15.4e (specified) . . . . . . . . . . . . . . . 7 74 3.8. Comparison between 6lo Link layer technologies . . . . . 8 75 4. 6lo Deployment Scenarios . . . . . . . . . . . . . . . . . . 9 76 4.1. jupitermesh in Smart Grid using 6lo in network layer . . 9 77 4.2. Wi-SUN usage of 6lo stacks . . . . . . . . . . . . . . . 11 78 4.3. G3-PLC usage of 6lo in network layer . . . . . . . . . . 12 79 4.4. Netricity usage of 6lo in network layer . . . . . . . . . 13 80 5. Design Space and Guidelines for 6lo Deployment . . . . . . . 14 81 5.1. Design Space Dimensions for 6lo Deployment . . . . . . . 14 82 5.2. Guidelines for adopting IPv6 stack (6lo/6LoWPAN) . . . . 16 83 6. 6lo Use Case Examples . . . . . . . . . . . . . . . . . . . . 17 84 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 85 8. Security Considerations . . . . . . . . . . . . . . . . . . . 18 86 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 87 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 88 10.1. Normative References . . . . . . . . . . . . . . . . . . 19 89 10.2. Informative References . . . . . . . . . . . . . . . . . 21 90 Appendix A. Other 6lo Use Case Examples . . . . . . . . . . . . 23 91 A.1. Use case of ITU-T G.9959: Smart Home . . . . . . . . . . 23 92 A.2. Use case of DECT-ULE: Smart Home . . . . . . . . . . . . 24 93 A.3. Use case of MS/TP: Building Automation Networks . . . . . 25 94 A.4. Use case of NFC: Alternative Secure Transfer . . . . . . 25 95 A.5. Use case of PLC: Smart Grid . . . . . . . . . . . . . . . 26 96 A.6. Use case of IEEE 802.15.4e: Industrial Automation . . . . 27 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 99 1. Introduction 101 Running IPv6 on constrained node networks has different features from 102 general node networks due to the characteristics of constrained node 103 networks such as small packet size, short link-layer address, low 104 bandwidth, network topology, low power, low cost, and large number of 105 devices [RFC4919][RFC7228]. For example, some IEEE 802.15.4 link 106 layers have a frame size of 127 octets and IPv6 requires the layer 107 below to support an MTU of 1280 bytes, therefore an appropriate 108 fragmentation and reassembly adaptation layer must be provided at the 109 layer below IPv6. Also, the limited size of IEEE 802.15.4 frame and 110 low energy consumption requirements make the need for header 111 compression. The IETF 6LoPWAN (IPv6 over Low powerWPAN) working 112 group published an adaptation layer for sending IPv6 packets over 113 IEEE 802.15.4 [RFC4944], which includes a compression format for IPv6 114 datagrams over IEEE 802.15.4-based networks [RFC6282], and Neighbor 115 Discovery Optimization for 6LoPWAN [RFC6775]. 117 As IoT (Internet of Things) services become more popular, IPv6 over 118 various link layer technologies such as Bluetooth Low Energy 119 (Bluetooth LE), ITU-T G.9959 (Z-Wave), Digital Enhanced Cordless 120 Telecommunications - Ultra Low Energy (DECT-ULE), Master-Slave/Token 121 Passing (MS/TP), Near Field Communication (NFC), Power Line 122 Communication (PLC), and IEEE 802.15.4e (TSCH), have been defined at 123 [IETF_6lo] working group. IPv6 stacks for constrained node networks 124 use a variation of the 6LoWPAN stack applied to each particular link 125 layer technology. 127 In the 6LoPWAN working group, the [RFC6568], "Design and Application 128 Spaces for 6LoWPANs" was published and it describes potential 129 application scenarios and use cases for low-power wireless personal 130 area networks. Hence, this 6lo applicability document aims to 131 provide guidance to an audience who are new to IPv6-over-low-power 132 networks concept and want to assess if variance of 6LoWPAN stack 133 [6lo] can be applied to the constrained layer two (L2) network of 134 their interest. This 6lo applicability document puts together 135 various design space dimensions such as deployment, network size, 136 power source, connectivity, multi-hop communication, traffic pattern, 137 security level, mobility, and QoS requirements etc. In addition, it 138 describes a few set of 6LoPWAN application scenarios and practical 139 deployment as examples. 141 This document provides the applicability and use cases of 6lo, 142 considering the following aspects: 144 o 6lo applicability and use cases MAY be uniquely different from 145 those of 6LoWPAN defined for IEEE 802.15.4. 147 o It SHOULD cover various IoT related wire/wireless link layer 148 technologies providing practical information of such technologies. 150 o A general guideline on how the 6LoWPAN stack can be modified for a 151 given L2 technology. 153 o Example use cases and practical deployment examples. 155 2. Conventions and Terminology 157 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 158 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 159 document are to be interpreted as described in [RFC2119]. 161 3. 6lo Link layer technologies and possible candidates 163 3.1. ITU-T G.9959 (specified) 165 The ITU-T G.9959 Recommendation [G.9959] targets low-power Personal 166 Area Networks (PANs), and defines physical layer and link layer 167 functionality. Physical layers of 9.6 kbit/s, 40 kbit/s and 100 168 kbit/s are supported. G.9959 defines how a unique 32-bit HomeID 169 network identifier is assigned by a network controller and how an 170 8-bit NodeID host identifier is allocated to each node. NodeIDs are 171 unique within the network identified by the HomeID. The G.9959 172 HomeID represents an IPv6 subnet that is identified by one or more 173 IPv6 prefixes [RFC7428]. The ITU-T G.9959 can be used for smart home 174 applications. 176 3.2. Bluetooth LE (specified) 178 Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth 179 4.1, and developed even further in successive versions. Bluetooth 180 SIG has also published Internet Protocol Support Profile (IPSP). The 181 IPSP enables discovery of IP-enabled devices and establishment of 182 link-layer connection for transporting IPv6 packets. IPv6 over 183 Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or 184 newer. 186 Many Devices such as mobile phones, notebooks, tablets and other 187 handheld computing devices which support Bluetooth 4.0 or subsequent 188 chipsets also support the low-energy variant of Bluetooth. Bluetooth 189 LE is also being included in many different types of accessories that 190 collaborate with mobile devices such as phones, tablets and notebook 191 computers. An example of a use case for a Bluetooth LE accessory is 192 a heart rate monitor that sends data via the mobile phone to a server 193 on the Internet [RFC7668]. A typical usage of Bluetooth LE is 194 smartphone-based interaction with constrained devices. Bluetooth LE 195 was originally designed to enable star topology networks. However, 196 recent Bluetooth versions support the formation of extended 197 topologies, and IPv6 support for mesh networks of Bluetooth LE 198 devices is being developed [I-D.ietf-6lo-blemesh] 200 3.3. DECT-ULE (specified) 202 DECT ULE is a low power air interface technology that is designed to 203 support both circuit switched services, such as voice communication, 204 and packet mode data services at modest data rate. 206 The DECT ULE protocol stack consists of the PHY layer operating at 207 frequencies in the 1880 - 1920 MHz frequency band depending on the 208 region and uses a symbol rate of 1.152 Mbps. Radio bearers are 209 allocated by use of FDMA/TDMA/TDD techniques. 211 In its generic network topology, DECT is defined as a cellular 212 network technology. However, the most common configuration is a star 213 network with a single Fixed Part (FP) defining the network with a 214 number of Portable Parts (PP) attached. The MAC layer supports 215 traditional DECT as this is used for services like discovery, 216 pairing, security features etc. All these features have been reused 217 from DECT. 219 The DECT ULE device can switch to the ULE mode of operation, 220 utilizing the new ULE MAC layer features. The DECT ULE Data Link 221 Control (DLC) provides multiplexing as well as segmentation and re- 222 assembly for larger packets from layers above. The DECT ULE layer 223 also implements per-message authentication and encryption. The DLC 224 layer ensures packet integrity and preserves packet order, but 225 delivery is based on best effort. 227 The current DECT ULE MAC layer standard supports low bandwidth data 228 broadcast. However the usage of this broadcast service has not yet 229 been standardized for higher layers [RFC8105]. DECT-ULE can be used 230 for smart metering in a home. 232 3.4. MS/TP (specified) 234 Master-Slave/Token-Passing (MS/TP) is a Medium Access Control (MAC) 235 protocol for the RS-485 [TIA-485-A] physical layer and is used 236 primarily in building automation networks. 238 An MS/TP device is typically based on a low-cost microcontroller with 239 limited processing power and memory. These constraints, together 240 with low data rates and a small MAC address space, are similar to 241 those faced in 6LoWPAN networks. MS/TP differs significantly from 242 6LoWPAN in at least three respects: a) MS/TP devices are typically 243 mains powered, b) all MS/TP devices on a segment can communicate 244 directly so there are no hidden node or mesh routing issues, and c) 245 the latest MS/TP specification provides support for large payloads, 246 eliminating the need for fragmentation and reassembly below IPv6. 248 MS/TP is designed to enable multidrop networks over shielded twisted 249 pair wiring. It can support network segments up to 1000 meters in 250 length at a data rate of 115.2 kbit/s or segments up to 1200 meters 251 in length at lower bit rates. An MS/TP interface requires only a 252 UART, an RS-485 [TIA-485-A] transceiver with a driver that can be 253 disabled, and a 5 ms resolution timer. The MS/TP MAC is typically 254 implemented in software. 256 Because of its superior "range" (~1 km) compared to many low power 257 wireless data links, MS/TP may be suitable to connect remote devices 258 (such as district heating controllers) to the nearest building 259 control infrastructure over a single link [RFC8163]. MS/TP can be 260 used for building automation networks. 262 3.5. NFC (specified) 264 NFC technology enables simple and safe two-way interactions between 265 electronic devices, allowing consumers to perform contactless 266 transactions, access digital content, and connect electronic devices 267 with a single touch. NFC complements many popular consumer level 268 wireless technologies, by utilizing the key elements in existing 269 standards for contactless card technology (ISO/IEC 14443 A&B and 270 JIS-X 6319-4). NFC can be compatible with existing contactless card 271 infrastructure and it enables a consumer to utilize one device across 272 different systems. 274 Extending the capability of contactless card technology, NFC also 275 enables devices to share information at a distance that is less than 276 10 cm with a maximum communication speed of 424 kbps. Users can 277 share business cards, make transactions, access information from a 278 smart poster or provide credentials for access control systems with a 279 simple touch. 281 NFC's bidirectional communication ability is ideal for establishing 282 connections with other technologies by the simplicity of touch. In 283 addition to the easy connection and quick transactions, simple data 284 sharing is also available [I-D.ietf-6lo-nfc]. NFC can be used for 285 secure transfer in healthcare services. 287 3.6. PLC (specified) 289 PLC is a data transmission technique that utilizes power conductors 290 as medium. Unlike other dedicated communication infrastructure, 291 power conductors are widely available indoors and outdoors. 292 Moreover, wired technologies are more susceptible to cause 293 interference but are more reliable than their wireless counterparts. 294 PLC is a data transmission technique that utilizes power conductors 295 as medium. 297 The below table shows some available open standards defining PLC. 299 +-------------+-----------------+------------+-----------+----------+ 300 | PLC Systems | Frequency Range | Type | Data Rate | Distance | 301 +-------------+-----------------+------------+-----------+----------+ 302 | IEEE1901 | <100MHz | Broadband | 200Mbps | 1000m | 303 | | | | | | 304 | IEEE1901.1 | <15MHz | PLC-IoT | 10Mbps | 2000m | 305 | | | | | | 306 | IEEE1901.2 | <500kHz | Narrowband | 200Kbps | 3000m | 307 +-------------+-----------------+------------+-----------+----------+ 309 Table 1: Some Available Open Standards in PLC 311 [IEEE1901] defines a broadband variant of PLC but is effective within 312 short range. This standard addresses the requirements of 313 applications with high data rate such as: Internet, HDTV, Audio, 314 Gaming etc. Broadband operates on OFDM (Orthogonal Frequency 315 Division Multiplexing) modulation. 317 [IEEE1901.2] defines a narrowband variant of PLC with less data rate 318 but significantly higher transmission range that could be used in an 319 indoor or even an outdoor environment. It is applicable to typical 320 IoT applications such as: Building Automation, Renewable Energy, 321 Advanced Metering, Street Lighting, Electric Vehicle, Smart Grid etc. 322 Moreover, IEEE 1901.2 standard is based on the 802.15.4 MAC sub-layer 323 and fully endorses the security scheme defined in 802.15.4 [RFC8036]. 324 A typical use case of PLC is smart grid. 326 3.7. IEEE 802.15.4e (specified) 328 The Time Slotted Channel Hopping (TSCH) mode was introduced in the 329 IEEE 802.15.4-2015 standard. In a TSCH network, all nodes are 330 synchronized. Time is sliced up into timeslots. The duration of a 331 timeslot, typically 10ms, is large enough for a node to send a full- 332 sized frame to its neighbor, and for that neighbor to send back an 333 acknowledgment to indicate successful reception. Timeslots are 334 grouped into one of more slotframes, which repeat over time. 336 All the communication in the network is orchestrated by a 337 communication schedule which indicates to each node what to do in 338 each of the timeslots of a slotframe: transmit, listen or sleep. The 339 communication schedule can be built so that the right amount of link- 340 layer resources (the cells in the schedule) are scheduled to satisfy 341 the communication needs of the applications running on the network, 342 while keeping the energy consumption of the nodes very low. Cells 343 can be scheduled in a collision-free way, introducing a high level of 344 determinism to the network. 346 A TSCH network exploits channel hopping: subsequent packet exchanges 347 between neighbor nodes are done on a different frequency. This means 348 that, if a frame isn't received, the transmitter node will re- 349 transmitt the frame on a different frequency. The resulting "channel 350 hopping" efficiently combats external interference and multi-path 351 fading. 353 The main benefits of IEEE 802.15.4 TSCH are: 355 - ultra high reliability. Off-the-shelf commercial products offer 356 over 99.999% end-to-end reliability. 358 - ultra low-power consumption. Off-the-shelf commercial products 359 offer over a decade of battery lifetime. 361 - 6TiSCH at IETF defines communications of TSCH network and it 362 uses 6LoWPAN stack [RFC7554]. 364 IEEE 802.15.4e can be used for industrial automation. 366 3.8. Comparison between 6lo Link layer technologies 368 In above clauses, various 6lo Link layer technologies and a possible 369 candidate are described. The following table shows that dominant 370 paramters of each use case corresponding to the 6lo link layer 371 technology. 373 +-----------+--------+--------+--------+--------+--------+--------+--------+ 374 | | Z-Wave | BLE |DECT-ULE| MS/TP | NFC | PLC | TSCH | 375 +-----------+--------+--------+--------+--------+--------+--------+--------+ 376 | | Home |Interact| |Building| Health-| |Industr-| 377 | Usage | Auto- |w/ Smart| Meter | Auto- | care | Smart |ial Aut-| 378 | | mation | Phone | Reading| mation | Service| Grid | mation | 379 +-----------+--------+--------+--------+--------+--------+--------+--------+ 380 | Topology | L2-mesh| Star | Star | MS/TP | P2P | Star | | 381 | & | or | & | | | | Tree | Mesh | 382 | Subnet | L3-mesh| Mesh | No mesh| No mesh| L2-mesh| Mesh | | 383 +-----------+--------+--------+--------+--------+--------+--------+--------+ 384 | | | | | | | | | 385 | Mobility | No | Low | No | No |Moderate| No | No | 386 | Reqmt | | | | | | | | 387 +-----------+--------+--------+--------+--------+--------+--------+--------+ 388 | | High + | | High + | High + | | High + | High + | 389 | Security | Privacy| Parti- | Privacy| Authen.| High |Encrypt.| Privacy| 390 | Reqmt |required| ally |required|required| |required|required| 391 +-----------+--------+--------+--------+--------+--------+--------+--------+ 392 | | | | | | | | | 393 | Buffering | Low | Low | Low | Low | Low | Low | Low | 394 | Reqmt | | | | | | | | 395 +-----------+--------+--------+--------+--------+--------+--------+--------+ 396 | Latency, | | | | | | | | 397 | QoS | High | Low | Low | High | High | Low | High | 398 | Reqmt | | | | | | | | 399 +-----------+--------+--------+--------+--------+--------+--------+--------+ 400 | | | | | | | | | 401 | Data |Infrequ-|Infrequ-|Infrequ-|Frequent| Small |Infrequ-|Infrequ-| 402 | Rate | ent | ent | ent | | | ent | ent | 403 +-----------+--------+--------+--------+--------+--------+--------+--------+ 404 | RFC # | | | | | draft- | draft- | | 405 | or | RFC7428| RFC7668| RFC8105| RFC8163|ietf-6lo|hou-6lo-| RFC7554| 406 | Draft | | | | | -nfc | plc | | 407 +-----------+--------+--------+--------+--------+--------+--------+--------+ 409 Table 2: Comparison between 6lo Link layer technologies 411 4. 6lo Deployment Scenarios 413 4.1. jupitermesh in Smart Grid using 6lo in network layer 415 jupiterMesh is a multi-hop wireless mesh network specification 416 designed mainly for deployment in large geographical areas. Each 417 subnet in jupiterMesh is able to cover an entire neighborhood with 418 thousands of nodes consisting of IPv6-enabled routers and end-points 419 (e.g. hosts). Automated network joining and load balancing allows a 420 seamless deployment of a large number of subnets. 422 The main application domains targeted by jupiterMesh are smart grid 423 and smart cities. This includes, but is not limited to the following 424 applications: 426 o Automated meter reading 428 o Distribution Automation (DA) 430 o Demand-side management (DSM) 432 o Demand-side response (DSR) 434 o Power outage reporting 436 o Street light monitoring and control 438 o Transformer load management 440 o EV charging coordination 442 o Energy theft 444 o Parking space locator 446 jupiterMesh specification is based on the following technologies: 448 o The PHY layer is based on IEEE 802.15.4 SUN specification [IEEE 449 802.15.4-2015], supporting multiple operating modes for deployment 450 in different regulatory domains and deployment scenarios in terms 451 of density and bandwidth requirements. jupiterMesh supports bit 452 rates from 50 kbps to 800 kbps, frame size up to 2048 bytes, up to 453 11 different RF bands and 3 modulation types (i.e., FSK, OQPSK and 454 OFDM). 456 o The MAC layer is based on IEEE 802.15.4 TSCH specification [IEEE 457 802.15.4-2015]. With frequency hopping capability, TSCH MAC 458 supports scheduling of dedicated timeslot enabling bandwidth 459 management and QoS. 461 o The security layer consists of a certificate-based (i.e. X.509) 462 network access authentication using EAP-TLS, with IEEE 463 802.15.9-based KMP (Key Management Protocol) transport, and PANA 464 and link layer encryption using AES-128 CCM as specified in IEEE 465 802.15.4-2015 [IEEE 802.15.4-2015]. 467 o Address assignment and network configuration are specified using 468 DHCPv6 [RFC3315]. Neighbor Discovery (ND) [RFC6775] and stateless 469 address auto-configuration (SLAAC) are not supported. 471 o The network layer consists of IPv6, ICMPv6 and 6lo/6LoPWAN header 472 compression [RFC6282]. Multicast is supported using MPL. Two 473 domains are supported, a delay sensitive MPL domain for low 474 latency applications (e.g. DSM, DSR) and a delay insensitive one 475 for less stringent applications (e.g. OTA file transfers). 477 o The routing layer uses RPL [RFC6550] in non-storing mode with the 478 MRHOF objective function based on the ETX metric. 480 4.2. Wi-SUN usage of 6lo stacks 482 Wireless Smart Ubiquitous Network (Wi-SUN) is a technology based on 483 the IEEE 802.15.4g standard. Wi-SUN networks support star and mesh 484 topologies, as well as hybrid star/mesh deployments, but are 485 typically laid out in a mesh topology where each node relays data for 486 the network to provide network connectivity. Wi-SUN networks are 487 deployed on both powered and battery-operated devices. 489 The main application domains targeted by Wi-SUN are smart utility and 490 smart city networks. This includes, but is not limited to the 491 following applications: 493 o Advanced Metering Infrastructure (AMI) 495 o Distribution Automation 497 o Home Energy Management 499 o Infrastructure Management 501 o Intelligent Transportation Systems 503 o Smart Street Lighting 505 o Agriculture 507 o Structural health (bridges, buildings etc) 509 o Monitoring and Asset Management 511 o Smart Thermostats, Air Conditioning and Heat Controls 513 o Energy Usage Information Displays 514 The Wi-SUN Alliance Field Area Network (FAN) covers primarily outdoor 515 networks, and its specification is oriented towards meeting the more 516 rigorous challenges of these environments. Examples include from 517 meter to outdoor access point/router for AMI and DR, or between 518 switches for DA. However, nothing in the profile restricts it to 519 outdoor use. It has the following features; 521 o Open standards based on IEEE802, IETF, TIA, ETSI 523 o Architecture is an IPv6 frequency hopping wireless mesh network 524 with enterprise level security 526 o Simple infrastructure which is low cost, low complexity 528 o Enhanced network robustness, reliability, and resilience to 529 interference, due to high redundancy and frequency hopping 531 o Enhaced scalability, long range, and energy friendliness 533 o Supports multiple global license-exempt sub GHz bands 535 o Multi-vendor interoperability 537 o Very low power modes in development permitting long term battery 538 operation of network nodes 540 In the Wi-SUN FAN specification, adaptation layer based on 6lo and 541 IPv6 network layer are described. So, IPv6 protocol suite including 542 TCP/UDP, 6lo Adaptation, Header Compression, DHCPv6 for IP address 543 management, Routing using RPL, ICMPv6, and Unicast/Multicast 544 forwarding is utilized. 546 4.3. G3-PLC usage of 6lo in network layer 548 G3-PLC [G3-PLC] is a narrow-band PLC technology that is based on 549 ITU-T G.9903 Recommendation [G.9903]. G3-PLC supports multi-hop mesh 550 network, and facilitates highly-reliable, long-range communication. 551 With the abilities to support IPv6 and to cross transformers, G3-PLC 552 is regarded as one of the next-generation NB-PLC technologies. 553 G3-PLC has got massive deployments over several countries, e.g. 554 Japan and France. 556 The main application domains targeted by G3-PLC are smart grid and 557 smart cities. This includes, but is not limited to the following 558 applications: 560 o Smart Metering 561 o Vehicle-to-Grid Communication 563 o Demand Response (DR) 565 o Distribution Automation 567 o Home/Building Energy Management Systems 569 o Smart Street Lighting 571 o Advanced Metering Infrastructure (AMI) backbone network 573 o Wind/Solar Farm Monitoring 575 In the G3-PLC specification, the 6lo adaptation layer utilizes the 576 6LoWPAN functions (e.g. header compression, fragmentation and 577 reassembly) so as to enable IPv6 packet transmission. LOADng, which 578 is a lightweight variant of AODV, is applied as the mesh-under 579 routing protocol in G3-PLC networks. Address assignment and network 580 configuration are based on the bootstrapping protocol specified in 581 ITU-T G.9903. The network layer consists of IPv6 and ICMPv6 while 582 the transport protocol UDP is used for data transmission. 584 4.4. Netricity usage of 6lo in network layer 586 The Netricity program in HomePlug Powerline Alliance [NETRICITY] 587 promotes the adoption of products built on the IEEE 1901.2 Low- 588 Frequency Narrow-Band PLC standard, which provides for urban and long 589 distance communications and propagation through transformers of the 590 distribution network using frequencies below 500 kHz. The technology 591 also addresses requirements that assure communication privacy and 592 secure networks. 594 The main application domains targeted by Netricity are smart grid and 595 smart cities. This includes, but is not limited to the following 596 applications: 598 o Utility grid modernization 600 o Distribution automation 602 o Meter-to-Grid connectivity 604 o Micro-grids 606 o Grid sensor communications 608 o Load control 609 o Demand response 611 o Net metering 613 o Street Lighting control 615 o Photovoltaic panel monitoring 617 Netricity system architecture is based on the PHY and MAC layers of 618 IEEE 1901.2 PLC standard. Regarding the 6lo adaptation layer and 619 IPv6 network layer, Netricity utilizes IPv6 protocol suite including 620 6lo/6LoWPAN header compression, DHCPv6 for IP address management, RPL 621 routing protocol, ICMPv6, and unicast/multicast forwarding. Note 622 that the layer 3 routing in Netricity uses RPL in non-storing mode 623 with the MRHOF objective function based on the own defined Estimated 624 Transmission Time (ETT) metric. 626 5. Design Space and Guidelines for 6lo Deployment 628 5.1. Design Space Dimensions for 6lo Deployment 630 The [RFC6568] lists the dimensions used to describe the design space 631 of wireless sensor networks in the context of the 6LoWPAN working 632 group. The design space is already limited by the unique 633 characteristics of a LoWPAN (e.g. low power, short range, low bit 634 rate). In [RFC6568], the following design space dimensions are 635 described: Deployment, Network size, Power source, Connectivity, 636 Multi-hop communication, Traffic pattern, Mobility, Quality of 637 Service (QoS). However, in this document, the following design space 638 dimensions are considered: 640 o Deployment/Bootstrapping: 6lo nodes can be connected randomly, or 641 in an organized manner. The bootstrapping has different 642 characteristics for each link layer technology. 644 o Topology: Topology of 6lo networks may inherently follow the 645 characteristics of each link layer technology. Point-to-point, 646 star, tree or mesh topologies can be configured, depending on the 647 link layer technology considered. 649 o L2-Mesh or L3-Mesh: L2-mesh and L3-mesh may inherently follow the 650 characteristics of each link layer technology. Some link layer 651 technologies may support L2-mesh and some may not support. 653 o Multi-link subnet, single subnet: The selection of multi-link 654 subnet and single subnet depends on connectivity and the number of 655 6lo nodes. 657 o Data rate: Typically, the link layer technologies of 6lo have low 658 rate of data transmission. But, by adjusting the MTU, it can 659 deliver higher upper layer data rate. 661 o Buffering requirements: Some 6lo use case may require more data 662 rate than the link layer technology support. In this case, a 663 buffering mechanism to manage the data is required. 665 o Security and Privacy Requirements: Some 6lo use case can involve 666 transferring some important and personal data between 6lo nodes. 667 In this case, high-level security support is required. 669 o Mobility across 6lo networks and subnets: The movement of 6lo 670 nodes depends on the 6lo use case. If the 6lo nodes can move or 671 moved around, a mobility management mechanism is required. 673 o Time synchronization requirements: The requirement of time 674 synchronization of the upper layer service is dependent on the 6lo 675 use case. For some 6lo use case related to health service, the 676 measured data must be recorded with exact time and must be 677 transferred with time synchronization. 679 o Reliability and QoS: Some 6lo use case requires high reliability, 680 for example real-time service or health-related services. 682 o Traffic patterns: 6lo use cases may involve various traffic 683 patterns. For example, some 6lo use case may require short data 684 length and random transmission. Some 6lo use case may require 685 continuous data and periodic data transmission. 687 o Security Bootstrapping: Without the external operations, 6lo nodes 688 must have the security bootstrapping mechanism. 690 o Power use strategy: to enable certain use cases, there may be 691 requirements on the class of energy availability and the strategy 692 followed for using power for communication [RFC7228]. Each link 693 layer technology defines a particular power use strategy which may 694 be tuned [I-D.ietf-lwig-energy-efficient]. Readers are expected 695 to be familiar with [RFC7228] terminology. 697 o Update firmware requirements: Most 6lo use cases will need a 698 mechanism for updating firmware. In these cases support for over 699 the air updates are required, probably in a broadcast mode when 700 bandwith is low and the number of identical devices is high. 702 o Wired vs. Wireless: Plenty of 6lo link layer technologies are 703 wireless, except MS/TP and PLC. The selection of wired or 704 wireless link layer technology is mainly dependent on the 705 requirement of 6lo use cases and the characteristics of wired/ 706 wireless technologies. For example, some 6lo use cases may 707 require easy and quick deployment, whereas others may need a 708 continuous source of power. 710 5.2. Guidelines for adopting IPv6 stack (6lo/6LoWPAN) 712 The following guideline targets new candidate constrained L2 713 technologies that may be considered for running modified 6LoWPAN 714 stack on top. The modification of 6LoWPAN stack should be based on 715 the following: 717 o Addressing Model: Addressing model determines whether the device 718 is capable of forming IPv6 Link-local and global addresses and 719 what is the best way to derive the IPv6 addresses for the 720 constrained L2 devices. Whether the device is capable of forming 721 IPv6 Link-local and global addresses, L2-address-derived IPv6 722 addresses are specified in [RFC4944], but there exist implications 723 for privacy. For global usage, a unique IPv6 address must be 724 derived using an assigned prefix and a unique interface ID. 725 [RFC8065] provides such guidelines. For MAC derived IPv6 address, 726 please refer to [RFC8163] for IPv6 address mapping examples. 727 Broadcast and multicast support are dependent on the L2 networks. 728 Most low-power L2 implementations map multicast to broadcast 729 networks. So care must be taken in the design when to use 730 broadcast and try to stick to unicast messaging whenever possible. 732 o MTU Considerations: The deployment SHOULD consider their need for 733 maximum transmission unit (MTU) of a packet over the link layer 734 and should consider if fragmentation and reassembly of packets are 735 needed at the 6LoWPAN layer. For example, if the link layer 736 supports fragmentation and reassembly of packets, then 6LoWPAN 737 layer may skip supporting fragmentation/reassembly. In fact, for 738 most efficiency, choosing a low-power link layer that can carry 739 unfragmented application packets would be optimum for packet 740 transmission if the deployment can afford it. Please refer to 6lo 741 RFCs [RFC7668], [RFC8163], [RFC8105] for example guidance. 743 o Mesh or L3-Routing: 6LoWPAN specifications do provide mechanisms 744 to support for mesh routing at L2. [RFC6550] defines layer three 745 (L3) routing for low power lossy networks using directed graphs. 746 6LoWPAN is routing protocol agnostic and other L2 or L3 routing 747 protocols can be run using a 6LoWPAN stack. 749 o Address Assignment: 6LoWPAN requires that IPv6 Neighbor Discovery 750 for low power networks [RFC6775] be used for autoconfiguration of 751 stateless IPv6 address assignment. Considering the energy 752 sensitive networks [RFC6775] makes optimization from classical 753 IPv6 ND [RFC4861] protocol. It is the responsibility of the 754 deployment to ensure unique global IPv6 addresses for the Internet 755 connectivity. For local-only connectivity IPv6 ULA may be used. 756 [RFC6775] specifies the 6LoWPAN border router(6LBR) which is 757 responsible for prefix assignment to the 6lo/6LoWPAN network. 6LBR 758 can be connected to the Internet or Enterprise network via its one 759 of the interfaces. Please refer to [RFC7668] and [RFC8105] for 760 examples of address assignment considerations. In addition, 761 privacy considerations [RFC8065] must be consulted for 762 applicability. In certain scenarios, the deployment may not 763 support autoconfiguration of IPv6 addressing due to regulatory and 764 business reasons and may choose to offer a separate address 765 assignment service. 767 o Header Compression: IPv6 header compression [RFC6282] is a vital 768 part of IPv6 over low power communication. Examples of header 769 compression for different link-layers specifications are found in 770 [RFC7668], [RFC8163], [RFC8105]. A generic header compression 771 technique is specified in [RFC7400]. 773 o Security and Encryption: Though 6LoWPAN basic specifications do 774 not address security at the network layer, the assumption is that 775 L2 security must be present. In addition, application level 776 security is highly desirable. The working groups [ace] and [core] 777 should be consulted for application and transport level security. 778 6lo working group is working on address authentication [6lo-ap-nd] 779 and secure bootstrapping is also being discussed at IETF. 780 However, there may be different levels of security available in a 781 deployment through other standards such as hardware level security 782 or certificates for initial booting process. Encryption is 783 important if the implementation can afford it. 785 o Additional processing: [RFC8066] defines guidelines for ESC 786 dispatch octets use in the 6LoWPAN header. An implementation may 787 take advantage of ESC header to offer a deployment specific 788 processing of 6LoWPAN packets. 790 6. 6lo Use Case Examples 792 As IPv6 stacks for constrained node networks use a variation of the 793 6LoWPAN stack applied to each particular link layer technology, 794 various 6lo use cases can be provided. In this clause, one 6lo use 795 case example of Bluetooth LE (Smartphone-Based Interaction with 796 Constrained Devices) is described. Other 6lo use case examples are 797 described in Appendix. 799 The key feature behind the current high Bluetooth LE momentum is its 800 support in a large majority of smartphones in the market. Bluetooth 801 LE can be used to allow the interaction between the smartphone and 802 surrounding sensors or actuators. Furthermore, Bluetooth LE is also 803 the main radio interface currently available in wearables. Since a 804 smartphone typically has several radio interfaces that provide 805 Internet access, such as Wi-Fi or 4G, the smartphone can act as a 806 gateway for nearby devices such as sensors, actuators or wearables. 807 Bluetooth LE may be used in several domains, including healthcare, 808 sports/wellness and home automation. 810 Example: Use of Bluetooth LE-based Body Area Network for fitness 812 A person wears a smartwatch for fitness purposes. The smartwatch has 813 several sensors (e.g. heart rate, accelerometer, gyrometer, GPS, 814 temperature, etc.), a display, and a Bluetooth LE radio interface. 815 The smartwatch can show fitness-related statistics on its display. 816 However, when a paired smartphone is in the range of the smartwatch, 817 the latter can report almost real-time measurements of its sensors to 818 the smartphone, which can forward the data to a cloud service on the 819 Internet. In addition, the smartwatch can receive notifications 820 (e.g. alarm signals) from the cloud service via the smartphone. On 821 the other hand, the smartphone may locally generate messages for the 822 smartwatch, such as e-mail reception or calendar notifications. 824 The functionality supported by the smartwatch may be complemented by 825 other devices such as other on-body sensors, wireless headsets or 826 head-mounted displays. All such devices may connect to the 827 smartphone creating a star topology network whereby the smartphone is 828 the central component. Support for extended network topologies (e.g. 829 mesh networks) is being developed as of the writing. 831 7. IANA Considerations 833 There are no IANA considerations related to this document. 835 8. Security Considerations 837 Security considerations are not directly applicable to this document. 838 The use cases will use the security requirements described in the 839 protocol specifications. 841 9. Acknowledgements 843 Carles Gomez has been funded in part by the Spanish Government 844 through the Jose Castillejo CAS15/00336 grant, and through the 845 TEC2016-79988-P grant. His contribution to this work has been 846 carried out in part during his stay as a visiting scholar at the 847 Computer Laboratory of the University of Cambridge. 849 Thomas Watteyne, Pascal Thubert, Xavier Vilajosana, Daniel Migault, 850 and Jianqiang HOU have provided valuable feedback for this draft. 852 Das Subir and Michel Veillette have provided valuable information of 853 jupiterMesh and Paul Duffy has provided valuable information of Wi- 854 SUN for this draft. Also, Jianqiang Hou has provided valuable 855 information of G3-PLC and Netricity for this draft. Kerry Lynn and 856 Dave Robin have provided valuable information of MS/TP and practical 857 use case of MS/TP for this draft. 859 Deoknyong Ko has provided relevant text of LTE-MTC and he shared his 860 experience to deploy IPv6 and 6lo technologies over LTE MTC in SK 861 Telecom. 863 10. References 865 10.1. Normative References 867 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 868 Requirement Levels", BCP 14, RFC 2119, 869 DOI 10.17487/RFC2119, March 1997, 870 . 872 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 873 over Low-Power Wireless Personal Area Networks (6LoWPANs): 874 Overview, Assumptions, Problem Statement, and Goals", 875 RFC 4919, DOI 10.17487/RFC4919, August 2007, 876 . 878 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 879 "Transmission of IPv6 Packets over IEEE 802.15.4 880 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 881 . 883 [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation 884 Routing Requirements in Low-Power and Lossy Networks", 885 RFC 5826, DOI 10.17487/RFC5826, April 2010, 886 . 888 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 889 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 890 DOI 10.17487/RFC6282, September 2011, 891 . 893 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 894 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 895 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 896 Low-Power and Lossy Networks", RFC 6550, 897 DOI 10.17487/RFC6550, March 2012, 898 . 900 [RFC6568] Kim, E., Kaspar, D., and JP. Vasseur, "Design and 901 Application Spaces for IPv6 over Low-Power Wireless 902 Personal Area Networks (6LoWPANs)", RFC 6568, 903 DOI 10.17487/RFC6568, April 2012, 904 . 906 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 907 Bormann, "Neighbor Discovery Optimization for IPv6 over 908 Low-Power Wireless Personal Area Networks (6LoWPANs)", 909 RFC 6775, DOI 10.17487/RFC6775, November 2012, 910 . 912 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 913 Constrained-Node Networks", RFC 7228, 914 DOI 10.17487/RFC7228, May 2014, 915 . 917 [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for 918 IPv6 over Low-Power Wireless Personal Area Networks 919 (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 920 2014, . 922 [RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets 923 over ITU-T G.9959 Networks", RFC 7428, 924 DOI 10.17487/RFC7428, February 2015, 925 . 927 [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using 928 IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the 929 Internet of Things (IoT): Problem Statement", RFC 7554, 930 DOI 10.17487/RFC7554, May 2015, 931 . 933 [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B., 934 Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low 935 Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015, 936 . 938 [RFC8036] Cam-Winget, N., Ed., Hui, J., and D. Popa, "Applicability 939 Statement for the Routing Protocol for Low-Power and Lossy 940 Networks (RPL) in Advanced Metering Infrastructure (AMI) 941 Networks", RFC 8036, DOI 10.17487/RFC8036, January 2017, 942 . 944 [RFC8065] Thaler, D., "Privacy Considerations for IPv6 Adaptation- 945 Layer Mechanisms", RFC 8065, DOI 10.17487/RFC8065, 946 February 2017, . 948 [RFC8066] Chakrabarti, S., Montenegro, G., Droms, R., and J. 949 Woodyatt, "IPv6 over Low-Power Wireless Personal Area 950 Network (6LoWPAN) ESC Dispatch Code Points and 951 Guidelines", RFC 8066, DOI 10.17487/RFC8066, February 952 2017, . 954 [RFC8105] Mariager, P., Petersen, J., Ed., Shelby, Z., Van de Logt, 955 M., and D. Barthel, "Transmission of IPv6 Packets over 956 Digital Enhanced Cordless Telecommunications (DECT) Ultra 957 Low Energy (ULE)", RFC 8105, DOI 10.17487/RFC8105, May 958 2017, . 960 [RFC8163] Lynn, K., Ed., Martocci, J., Neilson, C., and S. 961 Donaldson, "Transmission of IPv6 over Master-Slave/Token- 962 Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163, 963 May 2017, . 965 10.2. Informative References 967 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 968 C., and M. Carney, "Dynamic Host Configuration Protocol 969 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 970 2003, . 972 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 973 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 974 DOI 10.17487/RFC4861, September 2007, 975 . 977 [I-D.ietf-6lo-nfc] 978 Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi, 979 "Transmission of IPv6 Packets over Near Field 980 Communication", draft-ietf-6lo-nfc-09 (work in progress), 981 January 2018. 983 [I-D.ietf-lwig-energy-efficient] 984 Gomez, C., Kovatsch, M., Tian, H., and Z. Cao, "Energy- 985 Efficient Features of Internet of Things Protocols", 986 draft-ietf-lwig-energy-efficient-08 (work in progress), 987 October 2017. 989 [I-D.ietf-roll-aodv-rpl] 990 Anamalamudi, S., Zhang, M., Sangi, A., Perkins, C., Anand, 991 S., and B. Liu, "Asymmetric AODV-P2P-RPL in Low-Power and 992 Lossy Networks (LLNs)", draft-ietf-roll-aodv-rpl-03 (work 993 in progress), March 2018. 995 [I-D.ietf-6tisch-6top-sfx] 996 Dujovne, D., Grieco, L., Palattella, M., and N. Accettura, 997 "6TiSCH Experimental Scheduling Function (SFX)", draft- 998 ietf-6tisch-6top-sfx-01 (work in progress), March 2018. 1000 [I-D.ietf-6lo-blemesh] 1001 Gomez, C., Darroudi, S., and T. Savolainen, "IPv6 Mesh 1002 over BLUETOOTH(R) Low Energy using IPSP", draft-ietf-6lo- 1003 blemesh-02 (work in progress), September 2017. 1005 [I-D.satish-6tisch-6top-sf1] 1006 Anamalamudi, S., Liu, B., Zhang, M., Sangi, A., Perkins, 1007 C., and S. Anand, "Scheduling Function One (SF1): hop-by- 1008 hop Scheduling with RSVP-TE in 6tisch Networks", draft- 1009 satish-6tisch-6top-sf1-04 (work in progress), October 1010 2017. 1012 [IETF_6lo] 1013 "IETF IPv6 over Networks of Resource-constrained Nodes 1014 (6lo) working group", 1015 . 1017 [TIA-485-A] 1018 "TIA, "Electrical Characteristics of Generators and 1019 Receivers for Use in Balanced Digital Multipoint Systems", 1020 TIA-485-A (Revision of TIA-485)", March 2003, 1021 . 1024 [G3-PLC] "G3-PLC Alliance", . 1026 [NETRICITY] 1027 "Netricity program in HomePlug Powerline Alliance", 1028 . 1030 [G.9959] "International Telecommunication Union, "Short range 1031 narrow-band digital radiocommunication transceivers - PHY 1032 and MAC layer specifications", ITU-T Recommendation", 1033 January 2015. 1035 [G.9903] "International Telecommunication Union, "Narrowband 1036 orthogonal frequency division multiplexing power line 1037 communication transceivers for G3-PLC networks", ITU-T 1038 Recommendation", August 2017. 1040 [IEEE1901] 1041 "IEEE Standard, IEEE Std. 1901-2010 - IEEE Standard for 1042 Broadband over Power Line Networks: Medium Access Control 1043 and Physical Layer Specifications", 2010, 1044 . 1047 [IEEE1901.1] 1048 "IEEE Standard (work-in-progress), IEEE-SA Standards 1049 Board", . 1051 [IEEE1901.2] 1052 "IEEE Standard, IEEE Std. 1901.2-2013 - IEEE Standard for 1053 Low-Frequency (less than 500 kHz) Narrowband Power Line 1054 Communications for Smart Grid Applications", 2013, 1055 . 1058 [BACnet] "ASHRAE, "BACnet-A Data Communication Protocol for 1059 Building Automation and Control Networks", ANSI/ASHRAE 1060 Standard 135-2016", January 2016, 1061 . 1064 Appendix A. Other 6lo Use Case Examples 1066 A.1. Use case of ITU-T G.9959: Smart Home 1068 Z-Wave is one of the main technologies that may be used to enable 1069 smart home applications. Born as a proprietary technology, Z-Wave 1070 was specifically designed for this particular use case. Recently, 1071 the Z-Wave radio interface (physical and MAC layers) has been 1072 standardized as the ITU-T G.9959 specification. 1074 Example: Use of ITU-T G.9959 for Home Automation 1076 Variety of home devices (e.g. light dimmers/switches, plugs, 1077 thermostats, blinds/curtains and remote controls) are augmented with 1078 ITU-T G.9959 interfaces. A user may turn on/off or may control home 1079 appliances by pressing a wall switch or by pressing a button in a 1080 remote control. Scenes may be programmed, so that after a given 1081 event, the home devices adopt a specific configuration. Sensors may 1082 also periodically send measurements of several parameters (e.g. gas 1083 presence, light, temperature, humidity, etc.) which are collected at 1084 a sink device, or may generate commands for actuators (e.g. a smoke 1085 sensor may send an alarm message to a safety system). 1087 The devices involved in the described scenario are nodes of a network 1088 that follows the mesh topology, which is suitable for path diversity 1089 to face indoor multipath propagation issues. The multihop paradigm 1090 allows end-to-end connectivity when direct range communication is not 1091 possible. Security support is required, specially for safety-related 1092 communication. When a user interaction (e.g. a button press) 1093 triggers a message that encapsulates a command, if the message is 1094 lost, the user may have to perform further interactions to achieve 1095 the desired effect (e.g. a light is turned off). A reaction to a 1096 user interaction will be perceived by the user as immediate as long 1097 as the reaction takes place within 0.5 seconds [RFC5826]. 1099 A.2. Use case of DECT-ULE: Smart Home 1101 DECT is a technology widely used for wireless telephone 1102 communications in residential scenarios. Since DECT-ULE is a low- 1103 power variant of DECT, DECT-ULE can be used to connect constrained 1104 devices such as sensors and actuators to a Fixed Part, a device that 1105 typically acts as a base station for wireless telephones. Therefore, 1106 DECT-ULE is specially suitable for the connected home space in 1107 application areas such as home automation, smart metering, safety, 1108 healthcare, etc. 1110 Example: Use of DECT-ULE for Smart Metering 1112 The smart electricity meter of a home is equipped with a DECT-ULE 1113 transceiver. This device is in the coverage range of the Fixed Part 1114 of the home. The Fixed Part can act as a router connected to the 1115 Internet. This way, the smart meter can transmit electricity 1116 consumption readings through the DECT-ULE link with the Fixed Part, 1117 and the latter can forward such readings to the utility company using 1118 Wide Area Network (WAN) links. The meter can also receive queries 1119 from the utility company or from an advanced energy control system 1120 controlled by the user, which may also be connected to the Fixed Part 1121 via DECT-ULE. 1123 A.3. Use case of MS/TP: Building Automation Networks 1125 The primary use case for IPv6 over MS/TP (6LoBAC) is in building 1126 automation networks. [BACnet] is the open international standard 1127 protocol for building automation, and MS/TP is defined in [BACnet] 1128 Clause 9. MS/TP was designed to be a low cost multi-drop field bus 1129 to inter-connect the most numerous elements (sensors and actuators) 1130 of a building automation network to their controllers. A key aspect 1131 of 6LoBAC is that it is designed to co-exist with BACnet MS/TP on the 1132 same link, easing the ultimate transition of some BACnet networks to 1133 native end-to-end IPv6 transport protocols. New applications for 1134 6LoBAC may be found in other domains where low cost, long distance, 1135 and low latency are required. 1137 Example: Use of 6LoBAC in Building Automation Networks 1139 The majority of installations for MS/TP are for "terminal" or 1140 "unitary" controllers, i.e. single zone or room controllers that may 1141 connect to HVAC or other controls such as lighting or blinds. The 1142 economics of daisy-chaining a single twisted-pair between multiple 1143 devices is often preferred over home-run Cat-5 style wiring. 1145 A multi-zone controller might be implemented as an IP router between 1146 a traditional Ethernet link and several 6LoBAC links, fanning out to 1147 multiple terminal controllers. 1149 The superior distance capabilities of MS/TP (~1 km) compared to other 1150 6lo media may suggest its use in applications to connect remote 1151 devices to the nearest building infrastructure. for example, remote 1152 pumping or measuring stations with moderate bandwidth requirements 1153 can benefit from the low cost and robust capabilities of MS/TP over 1154 other wired technologies such as DSL, and without the line-of-site 1155 restrictions or hop-by-hop latency of many low cost wireless 1156 solutions. 1158 A.4. Use case of NFC: Alternative Secure Transfer 1160 According to applications, various secured data can be handled and 1161 transferred. Depending on security level of the data, methods for 1162 transfer can be alternatively selected. 1164 Example: Use of NFC for Secure Transfer in Healthcare Services with 1165 Tele-Assistance 1167 A senior citizen who lives alone wears one to several wearable 6lo 1168 devices to measure heartbeat, pulse rate, etc. The 6lo devices are 1169 densely installed at home for movement detection. An LoWPAN Border 1170 Router (LBR) at home will send the sensed information to a connected 1171 healthcare center. Portable base stations with LCDs may be used to 1172 check the data at home, as well. Data is gathered in both periodic 1173 and event-driven fashion. In this application, event-driven data can 1174 be very time-critical. In addition, privacy also becomes a serious 1175 issue in this case, as the sensed data is very personal. 1177 While the senior citizen is provided audio and video healthcare 1178 services by a tele-assistance based on LTE connections, the senior 1179 citizen can alternatively use NFC connections to transfer the 1180 personal sensed data to the tele-assistance. At this moment, hidden 1181 hackers can overhear the data based on the LTE connection, but they 1182 cannot gather the personal data over the NFC connection. 1184 A.5. Use case of PLC: Smart Grid 1186 Smart grid concept is based on numerous operational and energy 1187 measuring sub-systems of an electric grid. It comprises of multiple 1188 administrative levels/segments to provide connectivity among these 1189 numerous components. Last mile connectivity is established over LV 1190 segment, whereas connectivity over electricity distribution takes 1191 place in HV segment. 1193 Although other wired and wireless technologies are also used in Smart 1194 Grid (Advance Metering Infrastructure - AMI, Demand Response - DR, 1195 Home Energy Management System - HEMS, Wide Area Situational Awareness 1196 - WASA etc), PLC enjoys the advantage of existing (power conductor) 1197 medium and better reliable data communication. PLC is a promising 1198 wired communication technology in that the electrical power lines are 1199 already there and the deployment cost can be comparable to wireless 1200 technologies. The 6lo related scenarios lie in the low voltage PLC 1201 networks with most applications in the area of Advanced Metering 1202 Infrastructure, Vehicle-to-Grid communications, in-home energy 1203 management and smart street lighting. 1205 Example: Use of PLC for Advanced Metering Infrastructure 1207 Household electricity meters transmit time-based data of electric 1208 power consumption through PLC. Data concentrators receive all the 1209 meter data in their corresponding living districts and send them to 1210 the Meter Data Management System (MDMS) through WAN network (e.g. 1211 Medium-Voltage PLC, Ethernet or GPRS) for storage and analysis. Two- 1212 way communications are enabled which means smart meters can do 1213 actions like notification of electricity charges according to the 1214 commands from the utility company. 1216 With the existing power line infrastructure as communication medium, 1217 cost on building up the PLC network is naturally saved, and more 1218 importantly, labor operational costs can be minimized from a long- 1219 term perspective. Furthermore, this AMI application speeds up 1220 electricity charge, reduces losses by restraining power theft and 1221 helps to manage the health of the grid based on line loss analysis. 1223 Example: Use of PLC (IEEE1901.1) for WASA in Smart Grid 1225 Many sub-systems of Smart Grid require low data rate and narrowband 1226 variant (IEEE1901.2) of PLC fulfils such requirements. Recently, 1227 more complex scenarios are emerging that require higher data rates. 1229 WASA sub-system is an appropriate example that collects large amount 1230 of information about the current state of the grid over wide area 1231 from electric substations as well as power transmission lines. The 1232 collected feedback is used for monitoring, controlling and protecting 1233 all the sub-systems. 1235 A.6. Use case of IEEE 802.15.4e: Industrial Automation 1237 Typical scenario of Industrial Automation where sensor and actuators 1238 are connected through the time-slotted radio access (IEEE 802.15.4e). 1239 For that, there will be a point-to-point control signal exchange in 1240 between sensors and actuators to trigger the critical control 1241 information. In such scenarios, point-to-point traffic flows are 1242 significant to exchange the controlled information in between sensors 1243 and actuators within the constrained networks. 1245 Example: Use of IEEE 802.15.4e for P2P communication in closed-loop 1246 application 1248 AODV-RPL [I-D.ietf-roll-aodv-rpl] is proposed as a standard P2P 1249 routing protocol to provide the hop-by-hop data transmission in 1250 closed-loop constrained networks. Scheduling Functions i.e. SF0 1251 [I-D.ietf-6tisch-6top-sfx] and SF1 [I-D.satish-6tisch-6top-sf1] is 1252 proposed to provide distributed neighbor-to-neighbor and end-to-end 1253 resource reservations, respectively for traffic flows in 1254 deterministic networks (6TiSCH). 1256 The potential scenarios that can make use of the end-to-end resource 1257 reservations can be in health-care and industrial applications. 1258 AODV-RPL and SF0/SF1 are the significant routing and resource 1259 reservation protocols for closed-loop applications in constrained 1260 networks. 1262 Authors' Addresses 1263 Yong-Geun Hong 1264 ETRI 1265 161 Gajeong-Dong Yuseung-Gu 1266 Daejeon 305-700 1267 Korea 1269 Phone: +82 42 860 6557 1270 Email: yghong@etri.re.kr 1272 Carles Gomez 1273 Universitat Politecnica de Catalunya/Fundacio i2cat 1274 C/Esteve Terradas, 7 1275 Castelldefels 08860 1276 Spain 1278 Email: carlesgo@entel.upc.edu 1280 Younghwan Choi 1281 ETRI 1282 218 Gajeongno, Yuseong 1283 Daejeon 305-700 1284 Korea 1286 Phone: +82 42 860 1429 1287 Email: yhc@etri.re.kr 1289 Abdur Rashid Sangi 1290 Huaiyin Institute of Technology 1291 No.89 North Beijing Road, Qinghe District 1292 Huaian 223001 1293 P.R. China 1295 Email: sangi_bahrian@yahoo.com 1297 Take Aanstoot 1298 Modio AB 1299 S:t Larsgatan 15, 582 24 1300 Linkoping 1301 Sweden 1303 Email: take@modio.se 1304 Samita Chakrabarti 1305 San Jose, CA 1306 USA 1308 Email: samitac.ietf@gmail.com