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Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: draft-ietf-6lo-blemesh has been published as RFC 9159 == Outdated reference: A later version (-11) exists of draft-ietf-6lo-plc-05 == Outdated reference: draft-ietf-roll-useofrplinfo has been published as RFC 9008 == Outdated reference: draft-ietf-roll-unaware-leaves has been published as RFC 9010 == Outdated reference: draft-ietf-roll-turnon-rfc8138 has been published as RFC 9035 Summary: 1 error (**), 0 flaws (~~), 6 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6Lo Working Group Y-G. Hong 3 Internet-Draft 4 Intended status: Informational C. Gomez 5 Expires: August 25, 2021 UPC 6 Y-H. Choi 7 ETRI 8 AR. Sangi 9 Huaiyin Institute of Technology 10 S. Chakrabarti 11 February 21, 2021 13 IPv6 over Constrained Node Networks (6lo) Applicability & Use cases 14 draft-ietf-6lo-use-cases-10 16 Abstract 18 This document describes the applicability of IPv6 over constrained 19 node networks (6lo) and provides practical deployment examples. In 20 addition to IEEE 802.15.4, various link layer technologies such as 21 ITU-T G.9959 (Z-Wave), Bluetooth Low Energy, DECT-ULE, MS/TP, NFC, 22 and PLC are used as examples. The document targets an audience who 23 would like to understand and evaluate running end-to-end IPv6 over 24 the constrained node networks for local or Internet connectivity. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on August 25, 2021. 43 Copyright Notice 45 Copyright (c) 2021 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. 6lo Link layer technologies . . . . . . . . . . . . . . . . . 4 62 2.1. ITU-T G.9959 . . . . . . . . . . . . . . . . . . . . . . 4 63 2.2. Bluetooth LE . . . . . . . . . . . . . . . . . . . . . . 4 64 2.3. DECT-ULE . . . . . . . . . . . . . . . . . . . . . . . . 5 65 2.4. MS/TP . . . . . . . . . . . . . . . . . . . . . . . . . . 5 66 2.5. NFC . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 67 2.6. PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 2.7. Comparison between 6lo link layer technologies . . . . . 8 69 3. Guidelines for adopting IPv6 stack (6lo) . . . . . . . . . . 9 70 4. 6lo Deployment Scenarios . . . . . . . . . . . . . . . . . . 11 71 4.1. Wi-SUN usage of 6lo in network layer . . . . . . . . . . 11 72 4.2. Thread usage of 6lo in network layer . . . . . . . . . . 13 73 4.3. G3-PLC usage of 6lo in network layer . . . . . . . . . . 13 74 4.4. Netricity usage of 6lo in network layer . . . . . . . . . 14 75 5. 6lo Use Case Examples . . . . . . . . . . . . . . . . . . . . 15 76 5.1. Use case of ITU-T G.9959: Smart Home . . . . . . . . . . 15 77 5.2. Use case of Bluetooth LE: Smartphone-based Interaction . 16 78 5.3. Use case of DECT-ULE: Smart Home . . . . . . . . . . . . 16 79 5.4. Use case of MS/TP: Building Automation Networks . . . . . 17 80 5.5. Use case of NFC: Alternative Secure Transfer . . . . . . 18 81 5.6. Use case of PLC: Smart Grid . . . . . . . . . . . . . . . 18 82 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 83 7. Security Considerations . . . . . . . . . . . . . . . . . . . 19 84 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 85 9. Informative References . . . . . . . . . . . . . . . . . . . 20 86 Appendix A. Design Space Dimensions for 6lo Deployment . . . . . 25 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 89 1. Introduction 91 Running IPv6 on constrained node networks presents challenges, due to 92 the characteristics of these networks such as small packet size, low 93 power, low bandwidth, low cost, and large number of devices, among 94 others [RFC4919][RFC7228]. For example, many IEEE 802.15.4 variants 95 [IEEE802154] exhibit a frame size of 127 octets, whereas IPv6 96 requires its underlying layer to support an MTU of 1280 bytes. 97 Furthermore, those IEEE 802.15.4 variants do not offer fragmentation 98 and reassembly functionality. Therefore, an appropriate adaptation 99 layer supporting fragmentation and reassembly must be provided below 100 IPv6. Also, the limited IEEE 802.15.4 frame size and low energy 101 consumption requirements motivate the need for packet header 102 compression. The IETF IPv6 over Low-Power WPAN (6LoWPAN) working 103 group published a suite of specification that provide an adaptation 104 layer to support IPv6 over IEEE 802.15.4 comprising the following 105 functionality: 107 o Fragmentation and reassembly, address autoconfiguration, and a 108 frame format [RFC4944], 110 o IPv6 (and UDP) header compression [RFC6282], 112 o Neighbor Discovery Optimization for 6LoWPAN [RFC6775][RFC8505]. 114 As Internet of Things (IoT) services become more popular, the IETF 115 6lo working group [IETF_6lo] has defined adaptation layer 116 functionality to support IPv6 over various link layer technologies 117 other than IEEE 802.15.4, such as Bluetooth Low Energy (Bluetooth 118 LE), ITU-T G.9959 (Z-Wave), Digital Enhanced Cordless 119 Telecommunications - Ultra Low Energy (DECT-ULE), Master-Slave/Token 120 Passing (MS/TP), Near Field Communication (NFC), and Power Line 121 Communication (PLC). The 6lo adaptation layers use a variation of 122 the 6LoWPAN stack applied to each particular link layer technology. 124 The 6LoWPAN working group produced the document entitled "Design and 125 Application Spaces for 6LoWPANs" [RFC6568], which describes potential 126 application scenarios and use cases for low-power wireless personal 127 area networks. The present document aims to provide guidance to an 128 audience who are new to the IPv6 over constrained node networks (6lo) 129 concept and want to assess its application to the constrained node 130 network of their interest. This 6lo applicability document describes 131 a few sets of practical 6lo deployment scenarios and use cases 132 examples. In addition, it considers various network design space 133 dimensions such as deployment, network size, power source, 134 connectivity, multi-hop communication, traffic pattern, security 135 level, mobility, and QoS requirements etc. 137 This document provides the applicability and use cases of 6lo, 138 considering the following aspects: 140 o It covers various IoT-related wired/wireless link layer 141 technologies providing practical information of such technologies. 143 o It provides a general guideline on how the 6LoWPAN stack can be 144 modified for a given L2 technology. 146 o Various 6lo use cases and practical deployment examples are 147 described. 149 2. 6lo Link layer technologies 151 2.1. ITU-T G.9959 153 The ITU-T G.9959 Recommendation [G.9959] targets low-power Wireless 154 Personal Area Networks (WPANs), and defines physical layer and link 155 layer functionality. Physical layers of 9.6 kbit/s, 40 kbit/s and 156 100 kbit/s are supported. G.9959 defines how a unique 32-bit HomeID 157 network identifier is assigned by a network controller and how an 158 8-bit NodeID host identifier is allocated to each node. NodeIDs are 159 unique within the network identified by the HomeID. The G.9959 160 HomeID represents an IPv6 subnet that is identified by one or more 161 IPv6 prefixes [RFC7428]. The ITU-T G.9959 can be used for smart home 162 applications. 164 2.2. Bluetooth LE 166 Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth 167 4.1, and developed further in successive versions. Bluetooth SIG has 168 also published the Internet Protocol Support Profile (IPSP). The 169 IPSP enables discovery of IP-enabled devices and establishment of 170 link-layer connection for transporting IPv6 packets. IPv6 over 171 Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or 172 newer. 174 Many devices such as mobile phones, notebooks, tablets and other 175 handheld computing devices which support Bluetooth 4.0 or subsequent 176 versions also support the low-energy variant of Bluetooth. Bluetooth 177 LE is also being included in many different types of accessories that 178 collaborate with mobile devices. An example of a use case for a 179 Bluetooth LE accessory is a heart rate monitor that sends data via 180 the mobile phone to a server on the Internet [RFC7668]. A typical 181 usage of Bluetooth LE is smartphone-based interaction with 182 constrained devices. Bluetooth LE was originally designed to enable 183 star topology networks. However, recent Bluetooth versions support 184 the formation of extended topologies, and IPv6 support for mesh 185 networks of Bluetooth LE devices is being developed 186 [I-D.ietf-6lo-blemesh] 188 2.3. DECT-ULE 190 DECT-ULE is a low power air interface technology that is designed to 191 support both circuit switched services, such as voice communication, 192 and packet mode data services at modest data rate. 194 The DECT-ULE protocol stack consists of the physical layer operating 195 at frequencies in the dedicated 1880 - 1920 MHz frequency band 196 depending on the region and uses a symbol rate of 1.152 Mbps. Radio 197 bearers are allocated by use of FDMA/TDMA/TDD techniques. 199 In its generic network topology, DECT is defined as a cellular 200 network technology. However, the most common configuration is a star 201 network with a single Fixed Part (FP) defining the network with a 202 number of Portable Parts (PP) attached. The Medium Access Control 203 (MAC) layer supports traditional DECT as this is used for services 204 like discovery, pairing, security features etc. All these features 205 have been reused from DECT. 207 The DECT-ULE device can switch to the ULE mode of operation, 208 utilizing the new ULE MAC layer features. The DECT-ULE Data Link 209 Control (DLC) provides multiplexing as well as segmentation and re- 210 assembly for larger packets from layers above. The DECT-ULE layer 211 also implements per-message authentication and encryption. The DLC 212 layer ensures packet integrity and preserves packet order, but 213 delivery is based on best effort. 215 The current DECT-ULE MAC layer standard supports low bandwidth data 216 broadcast. However the usage of this broadcast service has not yet 217 been standardized for higher layers [RFC8105]. DECT-ULE can be used 218 for smart metering in a home. 220 2.4. MS/TP 222 MS/TP is a MAC protocol for the RS-485 [TIA-485-A] physical layer and 223 is used primarily in building automation networks. 225 An MS/TP device is typically based on a low-cost microcontroller with 226 limited processing power and memory. These constraints, together 227 with low data rates and a small MAC address space, are similar to 228 those faced in 6LoWPAN networks. MS/TP differs significantly from 229 6LoWPAN in at least three respects: a) MS/TP devices are typically 230 mains powered, b) all MS/TP devices on a segment can communicate 231 directly so there are no hidden node or mesh routing issues, and c) 232 the latest MS/TP specification provides support for large payloads, 233 eliminating the need for fragmentation and reassembly below IPv6. 235 MS/TP is designed to enable multidrop networks over shielded twisted 236 pair wiring. It can support network segments up to 1000 meters in 237 length at a data rate of 115.2 kbit/s or segments up to 1200 meters 238 in length at lower bit rates. An MS/TP interface requires only a 239 Universal Asynchronous Receiver-Transmitter (UART), an RS-485 240 [TIA-485-A] transceiver with a driver that can be disabled, and a 5 241 ms resolution timer. The MS/TP MAC is typically implemented in 242 software. 244 Because of its superior "range" (~1 km) compared to many low power 245 wireless data links, MS/TP may be suitable to connect remote devices 246 (such as district heating controllers) to the nearest building 247 control infrastructure over a single link [RFC8163]. 249 2.5. NFC 251 NFC technology enables simple and safe two-way interactions between 252 electronic devices, allowing consumers to perform contactless 253 transactions, access digital content, and connect electronic devices 254 with a single touch. NFC complements many popular consumer level 255 wireless technologies, by utilizing the key elements in existing 256 standards for contactless card technology (ISO/IEC 14443 A&B and 257 JIS-X 6319-4). 259 Extending the capability of contactless card technology, NFC also 260 enables devices to share information at a distance that is less than 261 10 cm with a maximum communication speed of 424 kbps. Users can 262 share business cards, make transactions, access information from a 263 smart poster or provide credentials for access control systems with a 264 simple touch. 266 NFC's bidirectional communication ability is ideal for establishing 267 connections with other technologies by the simplicity of touch. In 268 addition to the easy connection and quick transactions, simple data 269 sharing is also available [I-D.ietf-6lo-nfc]. NFC can be used for 270 secure transfer in healthcare services. 272 2.6. PLC 274 PLC is a data transmission technique that utilizes power conductors 275 as medium [I-D.ietf-6lo-plc]. Unlike other dedicated communication 276 infrastructure, power conductors are widely available indoors and 277 outdoors. Moreover, wired technologies cause less interference to 278 the radio medium than wireless technologies and are more reliable 279 than their wireless counterparts. 281 The below table shows some available open standards defining PLC. 283 +-------------+-----------------+------------+-----------+----------+ 284 | PLC Systems | Frequency Range | Type | Data Rate | Distance | 285 +-------------+-----------------+------------+-----------+----------+ 286 | IEEE1901 | <100MHz | Broadband | 200Mbps | 1000m | 287 | | | | | | 288 | IEEE1901.1 | <12MHz | PLC-IoT | 10Mbps | 2000m | 289 | | | | | | 290 | IEEE1901.2 | <500kHz | Narrowband | 200kbps | 3000m | 291 | | | | | | 292 | G3-PLC | <500kHz | Narrowband | 234kbps | 3000m | 293 +-------------+-----------------+------------+-----------+----------+ 295 Table 1: Some Available Open Standards in PLC 297 IEEE 1901 [IEEE1901] defines a broadband variant of PLC but is 298 effective within short range. This standard addresses the 299 requirements of applications with high data rate such as: Internet, 300 HDTV, Audio, Gaming etc. Broadband operates on Orthogonal Frequency 301 Division Multiplexing (OFDM) modulation. 303 IEEE 1902.1 [IEEE1901.1] defines a medium frequency band (less than 304 12 MHz) broadband PLC technology for smart grid applications based on 305 OFDM. By achieving an extended communication range with medium 306 speeds, this standard can be applied both in indoor and outdoor 307 scenarios, such as Advanced Metering Infrastructure (AMI), street 308 lighting, electric vehicle charging, smart city etc. 310 IEEE 1902.2 [IEEE1901.2] defines a narrowband variant of PLC with 311 less data rate but significantly higher transmission range that could 312 be used in an indoor or even an outdoor environment. It is 313 applicable to typical IoT applications such as: Building Automation, 314 Renewable Energy, Advanced Metering, Street Lighting, Electric 315 Vehicle, Smart Grid etc. Moreover, IEEE 1901.2 standard is based on 316 the 802.15.4 MAC sub-layer and fully endorses the security scheme 317 defined in 802.15.4 [RFC8036]. A typical use case of PLC is smart 318 grid. 320 G3-PLC [G3-PLC] is a narrowband PLC technology that is based on the 321 ITU-T G.9903 Recommendation [G.9903]. The ITU-T G.9903 322 Recommendation contains the physical layer and data link layer 323 specification for the G3-PLC narrowband OFDM power line communication 324 transceivers, for communications via alternating current and direct 325 current electric power lines over frequencies below 500 kHz. 327 2.7. Comparison between 6lo link layer technologies 329 In above clauses, various 6lo link layer technologies are described. 330 The following table shows dominant parameters of each use case 331 corresponding to the 6lo link layer technology. 333 +--------------+---------+---------+---------+---------+---------+---------+ 334 | | Z-Wave | BLE | DECT-ULE| MS/TP | NFC | PLC | 335 +--------------+---------+---------+---------+---------+---------+---------+ 336 | | Home | Interact| | Building| Health- | | 337 | Usage | Auto- | w/ Smart| Meter | Auto- | care | Smart | 338 | | mation | Phone | Reading | mation | Service | Grid | 339 +--------------+---------+---------+---------+---------+---------+---------+ 340 | Topology | L2-mesh | Star | Star | MS/TP | P2P | Star | 341 | & | or | & | | | | Tree | 342 | Subnet | L3-mesh | Mesh | No mesh | No mesh | L2-mesh | Mesh | 343 +--------------+---------+---------+---------+---------+---------+---------+ 344 | | | | | | | | 345 | Mobility | No | Low | No | No | Moderate| No | 346 | Requirement | | | | | | | 347 +--------------+---------+---------+---------+---------+---------+---------+ 348 | | High + | | High + | High + | | High + | 349 | Security | Privacy |Partially| Privacy | Authen. | High | Encrypt.| 350 | Requirement | required| | required| required| | required| 351 +--------------+---------+---------+---------+---------+---------+---------+ 352 | | | | | | | | 353 | Buffering | Low | Low | Low | Low | Low | Low | 354 | Requirement | | | | | | | 355 +--------------+---------+---------+---------+---------+---------+---------+ 356 | Latency, | | | | | | | 357 | QoS | High | Low | Low | High | High | Low | 358 | Requirement | | | | | | | 359 +--------------+---------+---------+---------+---------+---------+---------+ 360 | | | | | | | | 361 | Data | Infrequ-| Infrequ-| Infrequ-| Frequent| Small | Infrequ-| 362 | Rate | ent | ent | ent | | | ent | 363 +--------------+---------+---------+---------+---------+---------+---------+ 364 | RFC # | | RFC7668,| | | draft- | draft- | 365 | or | RFC7428 | ietf-6lo| RFC8105 | RFC8163 | ietf-6lo| ietf-6lo| 366 | Draft | | -blemesh| | | -nfc | -plc | 367 +--------------+---------+---------+---------+---------+---------+---------+ 369 Table 2: Comparison between 6lo link layer technologies 371 3. Guidelines for adopting IPv6 stack (6lo) 373 6lo aims at reusing and/or adapting existing 6LoWPAN functionality in 374 order to efficiently support IPv6 over a variety of IoT L2 375 technologies. The following guideline targets new candidate 376 constrained L2 technologies that may be considered for running a 377 modified 6LoWPAN stack on top. The modification of 6LoWPAN stack 378 should be based on the following: 380 o Addressing Model: Addressing model determines whether the device 381 is capable of forming IPv6 link-local and global addresses and 382 what is the best way to derive the IPv6 addresses for the 383 constrained L2 devices. L2-address-derived IPv6 addresses are 384 specified in [RFC4944], but there exist implications for privacy. 385 For global usage, a unique IPv6 address must be derived using an 386 assigned prefix and a unique interface ID. [RFC8065] provides 387 such guidelines. For MAC-derived IPv6 addresses, please refer to 388 [RFC8163] for IPv6 address mapping examples. Broadcast and 389 multicast support are dependent on the L2 networks. Most low- 390 power L2 implementations map multicast to broadcast networks. So 391 care must be taken in the design when to use broadcast and try to 392 stick to unicast messaging whenever possible. 394 o MTU Considerations: The deployment should consider packet maximum 395 transmission unit (MTU) needs over the link layer and should 396 consider if fragmentation and reassembly of packets are needed at 397 the 6LoWPAN layer. For example, if the link layer supports 398 fragmentation and reassembly of packets, then the 6LoWPAN layer 399 may not need to support fragmentation/reassembly. In fact, for 400 most efficiency, choosing a low-power link layer that can carry 401 unfragmented application packets would be optimum for packet 402 transmission if the deployment can afford it. Please refer to 6lo 403 RFCs [RFC7668], [RFC8163], [RFC8105] for example guidance. 405 o Mesh or L3-Routing: 6LoWPAN specifications provide mechanisms to 406 support mesh routing at L2, a configuration called mesh-under 407 [RFC6606]. It is also possible to use an L3 routing protocol in 408 6LoWPAN, an approach known as route-over. [RFC6550] defines RPL, 409 a L3 routing protocol for low power and lossy networks using 410 directed acyclic graphs. 6LoWPAN is routing-protocol-agnostic and 411 does not specify any particular L2 or L3 routing protocol to use 412 with a 6LoWPAN stack. 414 o Address Assignment: 6LoWPAN developed a new version of IPv6 415 Neighbor Discovery [RFC4861][RFC4862]. 6LoWPAN Neighbor Discovery 416 [RFC6775][RFC8505] inherits from IPv6 Neighbor Discovery for 417 mechanisms such as Stateless Address Autoconfiguration (SLAAC) and 418 Neighbor Unreachability Detection (NUD). A 6LoWPAN node is also 419 expected to be an IPv6 host per [RFC8200] which means it should 420 ignore consumed routing headers and Hop-by-Hop options; when 421 operating in a RPL network [RFC6550], it is also beneficial to 422 support IP-in-IP encapsulation [I-D.ietf-roll-useofrplinfo]. The 423 6LoWPAN node should also support [RFC8505] and use it as the 424 default Neighbor Discovery method. It is the responsibility of 425 the deployment to ensure unique global IPv6 addresses for Internet 426 connectivity. For local-only connectivity IPv6 Unique Local 427 Address (ULA) may be used. [RFC6775][RFC8505] specifies the 428 6LoWPAN border router (6LBR), which is responsible for prefix 429 assignment to the 6LoWPAN network. A 6LBR can be connected to the 430 Internet or to an enterprise network via one of the interfaces. 431 Please refer to [RFC7668] and [RFC8105] for examples of address 432 assignment considerations. In addition, privacy considerations 433 [RFC8065] must be consulted for applicability. In certain 434 scenarios, the deployment may not support IPv6 address 435 autoconfiguration due to regulatory and business reasons and may 436 choose to offer a separate address assignment service. Address 437 Protection for 6LoWPAN Neighbor Discovery (AP-ND) [RFC8928] 438 enables Source Address Validation [RFC6620] and protects the 439 address ownership against impersonation attacks. 441 o Broadcast Avoidance: 6LoWPAN Neighbor Discovery aims at reducing 442 the amount of multicast traffic of classical Neighbor Discovery, 443 since IP-level multicast translates into L2 broadcast in many L2 444 technologies. 6LoWPAN Neighbor Discovery relies on a proactive 445 registration to avoid the use of multicast for address resolution. 446 It also uses a unicast method for Duplicate Address Detection 447 (DAD), and avoids multicast lookups from all nodes by using non- 448 onlink prefixes. Router Advertisements (RAs) are also sent in 449 unicast, in response to Router Solicitations (RSs) 451 o Host-to-Router interface: 6lo has defined registration extensions 452 for 6LoWPAN Neighbor Discovery [RFC8505]. This effort provides a 453 host-to-router interface by which a host can request its router to 454 ensure reachability for the address registered with the router. 455 Note that functionality has been developed to ensure that such a 456 host can benefit from routing services in a RPL network 457 [I-D.ietf-roll-unaware-leaves] 459 o Proxy Neighbor Discovery: Further functionality also allows a 460 device (e.g. an energy-constrained device that needs to sleep most 461 of the time) to request proxy Neighbor Discovery services from a 462 6LoWPAN Backbone Router (6BBR) [RFC8505][RFC8929]. The latter 463 federates a number of links into a multilink subnet. 465 o Header Compression: IPv6 header compression [RFC6282] is a vital 466 part of IPv6 over low power communication. Examples of header 467 compression over different link-layer specifications are found in 468 [RFC7668], [RFC8163], [RFC8105]. A generic header compression 469 technique is specified in [RFC7400]. For 6LoWPAN networks where 470 RPL is the routing protocol, there exist 6LoWPAN header 471 compression extensions which allow to compress also the RPL 472 artifacts used when forwarding packets in the route-over mesh 473 [RFC8138] [I-D.ietf-roll-turnon-rfc8138] 475 o Security and Encryption: Though 6LoWPAN basic specifications do 476 not address security at the network layer, the assumption is that 477 L2 security must be present. In addition, application-level 478 security is highly desirable. The working groups [IETF_ace] and 479 [IETF_core] should be consulted for application and transport 480 level security. 6lo working group is working on address 481 authentication [RFC8928] and secure bootstrapping is also being 482 discussed at IETF. However, there may be different levels of 483 security available in a deployment through other standards such as 484 hardware-level security or certificates for initial booting 485 process. Encryption is important if the implementation can afford 486 it. 488 o Additional processing: [RFC8066] defines guidelines for ESC 489 dispatch octets use in the 6LoWPAN header. An implementation may 490 take advantage of ESC header to offer a deployment specific 491 processing of 6LoWPAN packets. 493 4. 6lo Deployment Scenarios 495 4.1. Wi-SUN usage of 6lo in network layer 497 Wireless Smart Ubiquitous Network (Wi-SUN)[Wi-SUN] is a technology 498 based on the IEEE 802.15.4g standard. Wi-SUN networks support star 499 and mesh topologies, as well as hybrid star/mesh deployments, but 500 these are typically laid out in a mesh topology where each node 501 relays data for the network to provide network connectivity. Wi-SUN 502 networks are deployed on both powered and battery-operated devices 503 [RFC8376]. 505 The main application domains targeted by Wi-SUN are smart utility and 506 smart city networks. This includes, but is not limited to the 507 following applications: 509 o Advanced Metering Infrastructure 511 o Distribution Automation 513 o Home Energy Management 514 o Infrastructure Management 516 o Intelligent Transportation Systems 518 o Smart Street Lighting 520 o Agriculture 522 o Structural health (bridges, buildings) 524 o Monitoring and Asset Management 526 o Smart Thermostats, Air Conditioning and Heat Controls 528 o Energy Usage Information Displays 530 The Wi-SUN Alliance Field Area Network (FAN) covers primarily outdoor 531 networks, and its specification is oriented towards meeting the more 532 rigorous challenges of these environments. It has the following 533 features: 535 o Open standards based on IEEE802, IETF, TIA, ETSI 537 o Architecture based on an IPv6 frequency hopping wireless mesh 538 network with enterprise-level security 540 o Simple infrastructure of low cost, low complexity 542 o Enhanced network robustness, reliability, and resilience to 543 interference, due to high redundancy and frequency hopping 545 o Enhanced scalability, long range, and energy friendliness 547 o Supports multiple global license-exempt sub-GHz bands 549 o Multi-vendor interoperability 551 o Very low power modes in development permitting long term battery 552 operation of network nodes 554 The Wi-SUN FAN specification defines an IPv6-based protocol suite 555 including TCP/UDP, IPv6, 6lo adaptation layer, DHCPv6 for IPv6 556 address management, RPL, and ICMPv6. 558 4.2. Thread usage of 6lo in network layer 560 Thread is an IPv6-based networking protocol stack built on open 561 standards, designed for smart home environments, and based on low- 562 power IEEE 802.15.4 mesh networks. Because of its IPv6 foundation, 563 Thread can support existing popular application layers and IoT 564 platforms, provide end-to-end security, ease development and enable 565 flexible and future-proof designs [Thread]. 567 The Thread specification uses the IEEE 802.15.4 [IEEE802154] physical 568 and MAC layers operating at 250 kbps in the 2.4 GHz band. The IEEE 569 802.15.4-2006 and IEEE 802.15.4-2015 versions of the specification 570 are used by Thread. 572 Thread devices use 6LoWPAN, as defined in [RFC4944][RFC6282], for 573 transmission of IPv6 Packets over IEEE 802.15.4 networks. Header 574 compression is used within the Thread network and devices 575 transmitting messages compress the IPv6 header to minimize the size 576 of the transmitted packet. The mesh header is supported for link- 577 layer (i.e., mesh under) forwarding. The mesh header as used in 578 Thread also allows efficient end-to-end fragmentation of messages 579 rather than the hop-by-hop fragmentation specified in [RFC4944]. 580 Mesh under routing in Thread is based on a distance vector protocol 581 in a full mesh topology. 583 4.3. G3-PLC usage of 6lo in network layer 585 G3-PLC [G3-PLC] is a narrowband PLC technology that is based on the 586 ITU-T G.9903 Recommendation [G.9903]. G3-PLC supports multi-hop mesh 587 network topology, and facilitates highly-reliable, long-range 588 communication. With the abilities to support IPv6 and to cross 589 transformers, G3-PLC is regarded as one of the next-generation 590 narrowband PLC technologies. G3-PLC has got massive deployments over 591 several countries, e.g. Japan and France. 593 The main application domains targeted by G3-PLC are smart grid and 594 smart cities. This includes, but is not limited to the following 595 applications: 597 o Smart Metering 599 o Vehicle-to-Grid Communication 601 o Demand Response 603 o Distribution Automation 605 o Home/Building Energy Management Systems 606 o Smart Street Lighting 608 o Advanced Metering Infrastructure (AMI) backbone network 610 o Wind/Solar Farm Monitoring 612 In the G3-PLC specification, the 6lo adaption layer utilizes the 613 6LoWPAN functions (e.g. header compression, fragmentation and 614 reassembly). However, due to the different characteristics of the 615 PLC media, the 6LoWPAN adaptation layer cannot perfectly fulfill the 616 requirements [I-D.ietf-6lo-plc]. The ESC dispatch type is used in 617 the G3-PLC to provide native mesh routing and bootstrapping 618 functionalities [RFC8066]. 620 4.4. Netricity usage of 6lo in network layer 622 The Netricity program in HomePlug Powerline Alliance [NETRICITY] 623 promotes the adoption of products built on the IEEE 1901.2 low- 624 frequency narrowband PLC standard, which provides for urban and long 625 distance communications and propagation through transformers of the 626 distribution network using frequencies below 500 kHz. The technology 627 also addresses requirements that assure communication privacy and 628 secure networks. 630 The main application domains targeted by Netricity are smart grid and 631 smart cities. This includes, but is not limited to the following 632 applications: 634 o Utility grid modernization 636 o Distribution automation 638 o Meter-to-Grid connectivity 640 o Micro-grids 642 o Grid sensor communications 644 o Load control 646 o Demand response 648 o Net metering 650 o Street Lighting control 652 o Photovoltaic panel monitoring 653 Netricity system architecture is based on the physical and MAC layers 654 of IEEE 1901.2 PLC standard. Regarding the 6lo adaptation layer and 655 IPv6 network layer, Netricity utilizes IPv6 protocol suite including 656 6lo/6LoWPAN header compression, DHCPv6 for IP address management, RPL 657 routing protocol, ICMPv6, and unicast/multicast forwarding. Note 658 that the L3 routing in Netricity uses RPL in non-storing mode with 659 the MRHOF objective function based on the own defined Estimated 660 Transmission Time (ETT) metric. 662 5. 6lo Use Case Examples 664 As IPv6 stacks for constrained node networks use a variation of the 665 6LoWPAN stack applied to each particular link layer technology, 666 various 6lo use cases can be provided. In this section, various 6lo 667 use cases which are based on different link layer technologies are 668 described. 670 5.1. Use case of ITU-T G.9959: Smart Home 672 Z-Wave is one of the main technologies that may be used to enable 673 smart home applications. Born as a proprietary technology, Z-Wave 674 was specifically designed for this particular use case. Recently, 675 the Z-Wave radio interface (physical and MAC layers) has been 676 standardized as the ITU-T G.9959 specification. 678 Example: Use of ITU-T G.9959 for Home Automation 680 Variety of home devices (e.g. light dimmers/switches, plugs, 681 thermostats, blinds/curtains and remote controls) are augmented with 682 ITU-T G.9959 interfaces. A user may turn on/off or may control home 683 appliances by pressing a wall switch or by pressing a button in a 684 remote control. Scenes may be programmed, so that after a given 685 event, the home devices adopt a specific configuration. Sensors may 686 also periodically send measurements of several parameters (e.g. gas 687 presence, light, temperature, humidity, etc.) which are collected at 688 a sink device, or may generate commands for actuators (e.g. a smoke 689 sensor may send an alarm message to a safety system). 691 The devices involved in the described scenario are nodes of a network 692 that follows the mesh topology, which is suitable for path diversity 693 to face indoor multipath propagation issues. The multihop paradigm 694 allows end-to-end connectivity when direct range communication is not 695 possible. Security support is required, specially for safety-related 696 communication. When a user interaction (e.g. a button press) 697 triggers a message that encapsulates a command, if the message is 698 lost, the user may have to perform further interactions to achieve 699 the desired effect (e.g. turning off a light). A reaction to a user 700 interaction will be perceived by the user as immediate as long as the 701 reaction takes place within 0.5 seconds [RFC5826]. 703 5.2. Use case of Bluetooth LE: Smartphone-based Interaction 705 The key feature behind the current high Bluetooth LE momentum is its 706 support in a large majority of smartphones in the market. Bluetooth 707 LE can be used to allow the interaction between the smartphone and 708 surrounding sensors or actuators. Furthermore, Bluetooth LE is also 709 the main radio interface currently available in wearables. Since a 710 smartphone typically has several radio interfaces that provide 711 Internet access, such as Wi-Fi or 4G, the smartphone can act as a 712 gateway for nearby devices such as sensors, actuators or wearables. 713 Bluetooth LE may be used in several domains, including healthcare, 714 sports/wellness and home automation. 716 Example: Use of Bluetooth LE-based Body Area Network for fitness 718 A person wears a smartwatch for fitness purposes. The smartwatch has 719 several sensors (e.g. heart rate, accelerometer, gyrometer, GPS, 720 temperature, etc.), a display, and a Bluetooth LE radio interface. 721 The smartwatch can show fitness-related statistics on its display. 722 However, when a paired smartphone is in the range of the smartwatch, 723 the latter can report almost real-time measurements of its sensors to 724 the smartphone, which can forward the data to a cloud service on the 725 Internet. 6lo enables this use case by providing efficient end-to-end 726 IPv6 support. In addition, the smartwatch can receive notifications 727 (e.g. alarm signals) from the cloud service via the smartphone. On 728 the other hand, the smartphone may locally generate messages for the 729 smartwatch, such as e-mail reception or calendar notifications. 731 The functionality supported by the smartwatch may be complemented by 732 other devices such as other on-body sensors, wireless headsets or 733 head-mounted displays. All such devices may connect to the 734 smartphone creating a star topology network whereby the smartphone is 735 the central component. Support for extended network topologies (e.g. 736 mesh networks) is being developed as of the writing. 738 5.3. Use case of DECT-ULE: Smart Home 740 DECT is a technology widely used for wireless telephone 741 communications in residential scenarios. Since DECT-ULE is a low- 742 power variant of DECT, DECT-ULE can be used to connect constrained 743 devices such as sensors and actuators to a Fixed Part, a device that 744 typically acts as a base station for wireless telephones. Therefore, 745 DECT-ULE is specially suitable for the connected home space in 746 application areas such as home automation, smart metering, safety, 747 healthcare, etc. Since DECT-ULE uses dedicated bandwidth, it avoids 748 the coexistence issues suffered by other technologies that use e.g. 749 ISM frequency bands. 751 Example: Use of DECT-ULE for Smart Metering 753 The smart electricity meter of a home is equipped with a DECT-ULE 754 transceiver. This device is in the coverage range of the Fixed Part 755 of the home. The Fixed Part can act as a router connected to the 756 Internet. This way, the smart meter can transmit electricity 757 consumption readings through the DECT-ULE link with the Fixed Part, 758 and the latter can forward such readings to the utility company using 759 Wide Area Network (WAN) links. The meter can also receive queries 760 from the utility company or from an advanced energy control system 761 controlled by the user, which may also be connected to the Fixed Part 762 via DECT-ULE. 764 5.4. Use case of MS/TP: Building Automation Networks 766 The primary use case for IPv6 over MS/TP (6LoBAC) is in building 767 automation networks. [BACnet] is the open international standard 768 protocol for building automation, and MS/TP is defined in [BACnet] 769 Clause 9. MS/TP was designed to be a low cost multi-drop field bus 770 to inter-connect the most numerous elements (sensors and actuators) 771 of a building automation network to their controllers. A key aspect 772 of 6LoBAC is that it is designed to co-exist with BACnet MS/TP on the 773 same link, easing the ultimate transition of some BACnet networks to 774 native end-to-end IPv6 transport protocols. New applications for 775 6LoBAC may be found in other domains where low cost, long distance, 776 and low latency are required. Note that BACnet comprises various 777 networking solutions other than MS/TP, including the recently emerged 778 BACnet IP. However, the latter is based on high speed Ethernet 779 infrastructure, and thus it falls outside of the constrained node 780 network scope. 782 Example: Use of 6LoBAC in Building Automation Networks 784 The majority of installations for MS/TP are for "terminal" or 785 "unitary" controllers, i.e. single zone or room controllers that may 786 connect to HVAC or other controls such as lighting or blinds. The 787 economics of daisy-chaining a single twisted-pair between multiple 788 devices is often preferred over home-run Cat-5 style wiring. 790 A multi-zone controller might be implemented as an IP router between 791 a traditional Ethernet link and several 6LoBAC links, fanning out to 792 multiple terminal controllers. 794 The superior distance capabilities of MS/TP (~1 km) compared to other 795 6lo media may suggest its use in applications to connect remote 796 devices to the nearest building infrastructure. For example, remote 797 pumping or measuring stations with moderate bandwidth requirements 798 can benefit from the low cost and robust capabilities of MS/TP over 799 other wired technologies such as DSL, and without the line-of-sight 800 restrictions or hop-by-hop latency of many low cost wireless 801 solutions. 803 5.5. Use case of NFC: Alternative Secure Transfer 805 In different applications, a variety of secured data can be handled 806 and transferred. Depending on the security level of the data, 807 different transfer methods can be alternatively selected. 809 Example: Use of NFC for Secure Transfer in Healthcare Services with 810 Tele-Assistance 812 A senior citizen who lives alone wears one to several wearable 6lo 813 devices to measure heartbeat, pulse rate, etc. The 6lo devices are 814 densely installed at home for movement detection. A 6LBR at home 815 will send the sensed information to a connected healthcare center. 816 Portable base stations with LCDs may be used to check the data at 817 home, as well. Data is gathered in both periodic and event-driven 818 fashion. In this application, event-driven data can be very time- 819 critical. In addition, privacy also becomes a serious issue in this 820 case, as the sensed data is very personal. 822 While the senior citizen is provided audio and video healthcare 823 services by a tele-assistance based on LTE connections, the senior 824 citizen can alternatively use NFC connections to transfer the 825 personal sensed data to the tele-assistance. Hidden hackers can 826 overhear the data based on the LTE connection, but they cannot gather 827 the personal data over the NFC connection. 829 5.6. Use case of PLC: Smart Grid 831 The smart grid concept is based on deploying numerous operational and 832 energy measuring sub-systems in an electricity grid system. It 833 comprises multiple administrative levels/segments to provide 834 connectivity among these numerous components. Last mile connectivity 835 is established over the Low Voltage (LV) segment, whereas 836 connectivity over electricity distribution takes place in the High 837 Voltage (HV) segment. Smart grid systems include Advanced Metering 838 Infrastructure (AMI), Demand Response (DR), Home Energy Management 839 System (HEMS), Wide Area Situational Awareness (WASA), among others. 841 Although other wired and wireless technologies are also used in Smart 842 Grid, PLC enjoys the advantage of reliable data communication over 843 electrical power lines that are already present, and the deployment 844 cost can be comparable to wireless technologies. The 6lo-related 845 scenarios for PLC mainly lie in the LV PLC networks with most 846 applications in the area of Advanced Metering Infrastructure, 847 Vehicle-to-Grid communications, in-home energy management and smart 848 street lighting. 850 Example: Use of PLC for Advanced Metering Infrastructure 852 Household electricity meters transmit time-based data of electric 853 power consumption through PLC. Data concentrators receive all the 854 meter data in their corresponding living districts and send them to 855 the Meter Data Management System (MDMS) through WAN network (e.g. 856 Medium-Voltage PLC, Ethernet or GPRS) for storage and analysis. Two- 857 way communications are enabled which means smart meters can do 858 actions like notification of electricity charges according to the 859 commands from the utility company. 861 With the existing power line infrastructure as communication medium, 862 cost on building up the PLC network is naturally saved, and more 863 importantly, labor operational costs can be minimized from a long- 864 term perspective. Furthermore, this AMI application speeds up 865 electricity charge, reduces losses by restraining power theft and 866 helps to manage the health of the grid based on line loss analysis. 868 Example: Use of PLC (IEEE1901.1) for WASA in Smart Grid 870 Many sub-systems of Smart Grid require low data rate and narrowband 871 variants (e.g., IEEE1901.1) of PLC fulfill such requirements. 872 Recently, more complex scenarios are emerging that require higher 873 data rates. 875 WASA sub-system is an appropriate example that collects large amount 876 of information about the current state of the grid over wide area 877 from electric substations as well as power transmission lines. The 878 collected feedback is used for monitoring, controlling and protecting 879 all the sub-systems. 881 6. IANA Considerations 883 There are no IANA considerations related to this document. 885 7. Security Considerations 887 Security considerations are not directly applicable to this document. 888 For the use cases, the security requirements described in the 889 protocol specifications apply. 891 8. Acknowledgements 893 Carles Gomez has been funded in part by the Spanish Government 894 through the Jose Castillejo CAS15/00336 grant, the TEC2016-79988-P 895 grant, and the PID2019-106808RA-I00 grant, and by Secretaria 896 d'Universitats i Recerca del Departament d'Empresa i Coneixement de 897 la Generalitat de Catalunya 2017 through grant SGR 376. His 898 contribution to this work has been carried out in part during his 899 stay as a visiting scholar at the Computer Laboratory of the 900 University of Cambridge. 902 Thomas Watteyne, Pascal Thubert, Xavier Vilajosana, Daniel Migault, 903 Jianqiang Hou, Kerry Lynn, S.V.R. Anand, and Seyed Mahdi Darroudi 904 have provided valuable feedback for this draft. 906 Das Subir and Michel Veillette have provided valuable information of 907 jupiterMesh and Paul Duffy has provided valuable information of Wi- 908 SUN for this draft. Also, Jianqiang Hou has provided valuable 909 information of G3-PLC and Netricity for this draft. Take Aanstoot, 910 Kerry Lynn, and Dave Robin have provided valuable information of MS/ 911 TP and practical use case of MS/TP for this draft. 913 Deoknyong Ko has provided relevant text of LTE-MTC and he shared his 914 experience to deploy IPv6 and 6lo technologies over LTE MTC in SK 915 Telecom. 917 9. Informative References 919 [BACnet] "ASHRAE, "BACnet-A Data Communication Protocol for 920 Building Automation and Control Networks", ANSI/ASHRAE 921 Standard 135-2016", January 2016, 922 . 925 [G.9903] "International Telecommunication Union, "Narrowband 926 orthogonal frequency division multiplexing power line 927 communication transceivers for G3-PLC networks", ITU-T 928 Recommendation", August 2017. 930 [G.9959] "International Telecommunication Union, "Short range 931 narrow-band digital radiocommunication transceivers - PHY 932 and MAC layer specifications", ITU-T Recommendation", 933 January 2015. 935 [G3-PLC] "G3-PLC Alliance", . 937 [IEEE1901] 938 "IEEE Standard, IEEE Std. 1901-2010 - IEEE Standard for 939 Broadband over Power Line Networks: Medium Access Control 940 and Physical Layer Specifications", 2010, 941 . 944 [IEEE1901.1] 945 "IEEE Standard, IEEE Std. 1901.1-2018 - IEEE Standard for 946 Medium Frequency (less than 12 MHz) Power Line 947 Communications for Smart Grid Applications", 2018, 948 . 950 [IEEE1901.2] 951 "IEEE Standard, IEEE Std. 1901.2-2013 - IEEE Standard for 952 Low-Frequency (less than 500 kHz) Narrowband Power Line 953 Communications for Smart Grid Applications", 2013, 954 . 957 [IEEE802154] 958 IEEE standard for Information Technology, "IEEE Std. 959 802.15.4, Part. 15.4: Wireless Medium Access Control (MAC) 960 and Physical Layer (PHY) Specifications for Low-Rate 961 Wireless Personal Area Networks". 963 [I-D.ietf-6lo-blemesh] 964 Gomez, C., Darroudi, S., Savolainen, T., and M. Spoerk, 965 "IPv6 Mesh over BLUETOOTH(R) Low Energy using IPSP", 966 draft-ietf-6lo-blemesh-09 (work in progress), December 967 2020. 969 [I-D.ietf-6lo-nfc] 970 Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi, 971 "Transmission of IPv6 Packets over Near Field 972 Communication", draft-ietf-6lo-nfc-17 (work in progress), 973 August 2020. 975 [I-D.ietf-6lo-plc] 976 Hou, J., Liu, B., Hong, Y., Tang, X., and C. Perkins, 977 "Transmission of IPv6 Packets over PLC Networks", draft- 978 ietf-6lo-plc-05 (work in progress), October 2020. 980 [I-D.ietf-roll-useofrplinfo] 981 Robles, I., Richardson, M., and P. Thubert, "Using RPI 982 Option Type, Routing Header for Source Routes and IPv6-in- 983 IPv6 encapsulation in the RPL Data Plane", draft-ietf- 984 roll-useofrplinfo-44 (work in progress), January 2021. 986 [I-D.ietf-roll-unaware-leaves] 987 Thubert, P. and M. Richardson, "Routing for RPL Leaves", 988 draft-ietf-roll-unaware-leaves-30 (work in progress), 989 January 2021. 991 [I-D.ietf-roll-turnon-rfc8138] 992 Thubert, P. and L. Zhao, "A RPL DODAG Configuration Option 993 for the 6LoWPAN Routing Header", draft-ietf-roll-turnon- 994 rfc8138-18 (work in progress), December 2020. 996 [IETF_6lo] 997 "IETF IPv6 over Networks of Resource-constrained Nodes 998 (6lo) working group", 999 . 1001 [IETF_ace] 1002 "IETF Authentication and Authorization for Constrained 1003 Environments (ace) working group", 1004 . 1006 [IETF_core] 1007 "IETF Constrained RESTful Environments (core) working 1008 group", . 1010 [Wi-SUN] "Wi-SUN Alliance", . 1012 [Thread] "Thread Group", . 1014 [NETRICITY] 1015 "Netricity program in HomePlug Powerline Alliance", 1016 . 1018 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1019 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1020 DOI 10.17487/RFC4861, September 2007, 1021 . 1023 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1024 Address Autoconfiguration", RFC 4862, 1025 DOI 10.17487/RFC4862, September 2007, 1026 . 1028 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 1029 over Low-Power Wireless Personal Area Networks (6LoWPANs): 1030 Overview, Assumptions, Problem Statement, and Goals", 1031 RFC 4919, DOI 10.17487/RFC4919, August 2007, 1032 . 1034 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 1035 "Transmission of IPv6 Packets over IEEE 802.15.4 1036 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 1037 . 1039 [RFC5826] Brandt, A., Buron, J., and G. Porcu, "Home Automation 1040 Routing Requirements in Low-Power and Lossy Networks", 1041 RFC 5826, DOI 10.17487/RFC5826, April 2010, 1042 . 1044 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 1045 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 1046 DOI 10.17487/RFC6282, September 2011, 1047 . 1049 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1050 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1051 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1052 Low-Power and Lossy Networks", RFC 6550, 1053 DOI 10.17487/RFC6550, March 2012, 1054 . 1056 [RFC6568] Kim, E., Kaspar, D., and JP. Vasseur, "Design and 1057 Application Spaces for IPv6 over Low-Power Wireless 1058 Personal Area Networks (6LoWPANs)", RFC 6568, 1059 DOI 10.17487/RFC6568, April 2012, 1060 . 1062 [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem 1063 Statement and Requirements for IPv6 over Low-Power 1064 Wireless Personal Area Network (6LoWPAN) Routing", 1065 RFC 6606, DOI 10.17487/RFC6606, May 2012, 1066 . 1068 [RFC6620] Nordmark, E., Bagnulo, M., and E. Levy-Abegnoli, "FCFS 1069 SAVI: First-Come, First-Served Source Address Validation 1070 Improvement for Locally Assigned IPv6 Addresses", 1071 RFC 6620, DOI 10.17487/RFC6620, May 2012, 1072 . 1074 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1075 Bormann, "Neighbor Discovery Optimization for IPv6 over 1076 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1077 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1078 . 1080 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 1081 Constrained-Node Networks", RFC 7228, 1082 DOI 10.17487/RFC7228, May 2014, 1083 . 1085 [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for 1086 IPv6 over Low-Power Wireless Personal Area Networks 1087 (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 1088 2014, . 1090 [RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets 1091 over ITU-T G.9959 Networks", RFC 7428, 1092 DOI 10.17487/RFC7428, February 2015, 1093 . 1095 [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B., 1096 Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low 1097 Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015, 1098 . 1100 [RFC8036] Cam-Winget, N., Ed., Hui, J., and D. Popa, "Applicability 1101 Statement for the Routing Protocol for Low-Power and Lossy 1102 Networks (RPL) in Advanced Metering Infrastructure (AMI) 1103 Networks", RFC 8036, DOI 10.17487/RFC8036, January 2017, 1104 . 1106 [RFC8065] Thaler, D., "Privacy Considerations for IPv6 Adaptation- 1107 Layer Mechanisms", RFC 8065, DOI 10.17487/RFC8065, 1108 February 2017, . 1110 [RFC8066] Chakrabarti, S., Montenegro, G., Droms, R., and J. 1111 Woodyatt, "IPv6 over Low-Power Wireless Personal Area 1112 Network (6LoWPAN) ESC Dispatch Code Points and 1113 Guidelines", RFC 8066, DOI 10.17487/RFC8066, February 1114 2017, . 1116 [RFC8105] Mariager, P., Petersen, J., Ed., Shelby, Z., Van de Logt, 1117 M., and D. Barthel, "Transmission of IPv6 Packets over 1118 Digital Enhanced Cordless Telecommunications (DECT) Ultra 1119 Low Energy (ULE)", RFC 8105, DOI 10.17487/RFC8105, May 1120 2017, . 1122 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 1123 "IPv6 over Low-Power Wireless Personal Area Network 1124 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 1125 April 2017, . 1127 [RFC8163] Lynn, K., Ed., Martocci, J., Neilson, C., and S. 1128 Donaldson, "Transmission of IPv6 over Master-Slave/Token- 1129 Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163, 1130 May 2017, . 1132 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1133 (IPv6) Specification", STD 86, RFC 8200, 1134 DOI 10.17487/RFC8200, July 2017, 1135 . 1137 [RFC8352] Gomez, C., Kovatsch, M., Tian, H., and Z. Cao, Ed., 1138 "Energy-Efficient Features of Internet of Things 1139 Protocols", RFC 8352, DOI 10.17487/RFC8352, April 2018, 1140 . 1142 [RFC8376] Farrell, S., Ed., "Low-Power Wide Area Network (LPWAN) 1143 Overview", RFC 8376, DOI 10.17487/RFC8376, May 2018, 1144 . 1146 [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. 1147 Perkins, "Registration Extensions for IPv6 over Low-Power 1148 Wireless Personal Area Network (6LoWPAN) Neighbor 1149 Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, 1150 . 1152 [RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik, 1153 "Address-Protected Neighbor Discovery for Low-Power and 1154 Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November 1155 2020, . 1157 [RFC8929] Thubert, P., Ed., Perkins, C., and E. Levy-Abegnoli, "IPv6 1158 Backbone Router", RFC 8929, DOI 10.17487/RFC8929, November 1159 2020, . 1161 [TIA-485-A] 1162 "TIA, "Electrical Characteristics of Generators and 1163 Receivers for Use in Balanced Digital Multipoint Systems", 1164 TIA-485-A (Revision of TIA-485)", March 2003, 1165 . 1168 Appendix A. Design Space Dimensions for 6lo Deployment 1170 The [RFC6568] lists the dimensions used to describe the design space 1171 of wireless sensor networks in the context of the 6LoWPAN working 1172 group. The design space is already limited by the unique 1173 characteristics of a LoWPAN (e.g. low power, short range, low bit 1174 rate). In [RFC6568], the following design space dimensions are 1175 described: Deployment, Network size, Power source, Connectivity, 1176 Multi-hop communication, Traffic pattern, Mobility, Quality of 1177 Service (QoS). However, in this document, the following design space 1178 dimensions are considered: 1180 o Deployment/Bootstrapping: 6lo nodes can be connected randomly, or 1181 in an organized manner. The bootstrapping has different 1182 characteristics for each link layer technology. 1184 o Topology: Topology of 6lo networks may inherently follow the 1185 characteristics of each link layer technology. Point-to-point, 1186 star, tree or mesh topologies can be configured, depending on the 1187 link layer technology considered. 1189 o L2-Mesh or L3-Mesh: L2-mesh and L3-mesh may inherently follow the 1190 characteristics of each link layer technology. Some link layer 1191 technologies may support L2-mesh and some may not support. 1193 o Multi-link subnet, single subnet: The selection of multi-link 1194 subnet and single subnet depends on connectivity and the number of 1195 6lo nodes. 1197 o Data rate: Typically, the link layer technologies of 6lo have low 1198 rate of data transmission. But, by adjusting the MTU, it can 1199 deliver higher upper layer data rate. 1201 o Buffering requirements: Some 6lo use case may require more data 1202 rate than the link layer technology support. In this case, a 1203 buffering mechanism to manage the data is required. 1205 o Security and Privacy Requirements: Some 6lo use case can involve 1206 transferring some important and personal data between 6lo nodes. 1207 In this case, high-level security support is required. 1209 o Mobility across 6lo networks and subnets: The movement of 6lo 1210 nodes depends on the 6lo use case. If the 6lo nodes can move or 1211 moved around, a mobility management mechanism is required. 1213 o Time synchronization requirements: The requirement of time 1214 synchronization of the upper layer service is dependent on the 6lo 1215 use case. For some 6lo use case related to health service, the 1216 measured data must be recorded with exact time and must be 1217 transferred with time synchronization. 1219 o Reliability and QoS: Some 6lo use case requires high reliability, 1220 for example real-time service or health-related services. 1222 o Traffic patterns: 6lo use cases may involve various traffic 1223 patterns. For example, some 6lo use case may require short data 1224 length and random transmission. Some 6lo use case may require 1225 continuous data and periodic data transmission. 1227 o Security Bootstrapping: Without the external operations, 6lo nodes 1228 must have the security bootstrapping mechanism. 1230 o Power use strategy: to enable certain use cases, there may be 1231 requirements on the class of energy availability and the strategy 1232 followed for using power for communication [RFC7228]. Each link 1233 layer technology defines a particular power use strategy which may 1234 be tuned [RFC8352]. Readers are expected to be familiar with 1235 [RFC7228] terminology. 1237 o Update firmware requirements: Most 6lo use cases will need a 1238 mechanism for updating firmware. In these cases support for over 1239 the air updates are required, probably in a broadcast mode when 1240 bandwidth is low and the number of identical devices is high. 1242 o Wired vs. Wireless: Plenty of 6lo link layer technologies are 1243 wireless, except MS/TP and PLC. The selection of wired or 1244 wireless link layer technology is mainly dependent on the 1245 requirement of 6lo use cases and the characteristics of wired/ 1246 wireless technologies. For example, some 6lo use cases may 1247 require easy and quick deployment, whereas others may need a 1248 continuous source of power. 1250 Authors' Addresses 1252 Yong-Geun Hong 1253 Daejeon 1254 Korea 1256 Email: yonggeun.hong@gmail.com 1258 Carles Gomez 1259 Universitat Politecnica de Catalunya/Fundacio i2cat 1260 C/Esteve Terradas, 7 1261 Castelldefels 08860 1262 Spain 1264 Email: carlesgo@entel.upc.edu 1265 Younghwan Choi 1266 ETRI 1267 218 Gajeongno, Yuseong 1268 Daejeon 34129 1269 Korea 1271 Phone: +82 42 860 1429 1272 Email: yhc@etri.re.kr 1274 Abdur Rashid Sangi 1275 Huaiyin Institute of Technology 1276 No.89 North Beijing Road, Qinghe District 1277 Huaian 223001 1278 P.R. China 1280 Email: sangi_bahrian@yahoo.com 1282 Samita Chakrabarti 1283 San Jose, CA 1284 USA 1286 Email: samitac.ietf@gmail.com