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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPWAVE Working Group J. Jeong, Ed. 3 Internet-Draft Sungkyunkwan University 4 Intended status: Informational July 7, 2020 5 Expires: January 8, 2021 7 IPv6 Wireless Access in Vehicular Environments (IPWAVE): Problem 8 Statement and Use Cases 9 draft-ietf-ipwave-vehicular-networking-16 11 Abstract 13 This document discusses the problem statement and use cases of 14 IPv6-based vehicular networking for Intelligent Transportation 15 Systems (ITS). The main scenarios of vehicular communications are 16 vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and 17 vehicle-to-everything (V2X) communications. First, this document 18 explains use cases using V2V, V2I, and V2X networking. Next, for 19 IPv6-based vehicular networks, it makes a gap analysis of current 20 IPv6 protocols (e.g., IPv6 Neighbor Discovery, Mobility Management, 21 and Security & Privacy), and then lists up requirements for the 22 extensions of those IPv6 protocols for IPv6-based vehicular 23 networking. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on January 8, 2021. 42 Copyright Notice 44 Copyright (c) 2020 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6 62 3.1. V2V . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 63 3.2. V2I . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 64 3.3. V2X . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 65 4. Vehicular Networks . . . . . . . . . . . . . . . . . . . . . 11 66 4.1. Vehicular Network Architecture . . . . . . . . . . . . . 12 67 4.2. V2I-based Internetworking . . . . . . . . . . . . . . . . 16 68 4.3. V2V-based Internetworking . . . . . . . . . . . . . . . . 19 69 5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 20 70 5.1. Neighbor Discovery . . . . . . . . . . . . . . . . . . . 21 71 5.1.1. Link Model . . . . . . . . . . . . . . . . . . . . . 22 72 5.1.2. MAC Address Pseudonym . . . . . . . . . . . . . . . . 24 73 5.1.3. Routing . . . . . . . . . . . . . . . . . . . . . . . 25 74 5.2. Mobility Management . . . . . . . . . . . . . . . . . . . 25 75 6. Security Considerations . . . . . . . . . . . . . . . . . . . 26 76 7. Informative References . . . . . . . . . . . . . . . . . . . 29 77 Appendix A. Changes from draft-ietf-ipwave-vehicular- 78 networking-15 . . . . . . . . . . . . . . . . . . . 36 79 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 36 80 Appendix C. Contributors . . . . . . . . . . . . . . . . . . . . 36 81 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 39 83 1. Introduction 85 Vehicular networking studies have mainly focused on improving safety 86 and efficiency, and also enabling entertainment in vehicular 87 networks. The Federal Communications Commission (FCC) in the US 88 allocated wireless channels for Dedicated Short-Range Communications 89 (DSRC) [DSRC] in the Intelligent Transportation Systems (ITS) with 90 the frequency band of 5.850 - 5.925 GHz (i.e., 5.9 GHz band). DSRC- 91 based wireless communications can support vehicle-to-vehicle (V2V), 92 vehicle-to-infrastructure (V2I), and vehicle-to-everything (V2X) 93 networking. The European Union (EU) allocated radio spectrum for 94 safety-related and non-safety-related applications of ITS with the 95 frequency band of 5.875 - 5.905 GHz, as part of the Commission 96 Decision 2008/671/EC [EU-2008-671-EC]. 98 For direct inter-vehicular wireless connectivity, IEEE has amended 99 standard 802.11 (commonly known as Wi-Fi) to enable safe driving 100 services based on DSRC for the Wireless Access in Vehicular 101 Environments (WAVE) system. The Physical Layer (L1) and Data Link 102 Layer (L2) issues are addressed in IEEE 802.11p [IEEE-802.11p] for 103 the PHY and MAC of the DSRC, while IEEE 1609.2 [WAVE-1609.2] covers 104 security aspects, IEEE 1609.3 [WAVE-1609.3] defines related services 105 at network and transport layers, and IEEE 1609.4 [WAVE-1609.4] 106 specifies the multi-channel operation. IEEE 802.11p was first a 107 separate amendment, but was later rolled into the base 802.11 108 standard (IEEE 802.11-2012) as IEEE 802.11 Outside the Context of a 109 Basic Service Set (OCB) in 2012 [IEEE-802.11-OCB]. 111 3GPP has standardized Cellular Vehicle-to-Everything (C-V2X) 112 communications to support V2X in LTE mobile networks (called LTE V2X) 113 and V2X in 5G mobile networks (called 5G V2X) [TS-23.285-3GPP] 114 [TR-22.886-3GPP][TS-23.287-3GPP]. With C-V2X, vehicles can directly 115 communicate with each other without relay nodes (e.g., eNodeB in LTE 116 and gNodeB in 5G). 118 Along with these WAVE standards and C-V2X standards, regardless of a 119 wireless access technology under the IP stack of a vehicle, vehicular 120 networks can operate IP mobility with IPv6 [RFC8200] and Mobile IPv6 121 protocols (e.g., Mobile IPv6 (MIPv6) [RFC6275], Proxy MIPv6 (PMIPv6) 122 [RFC5213], Distributed Mobility Management (DMM) [RFC7333], Locator/ 123 ID Separation Protocol (LISP) [RFC6830BIS], and Asymmetric Extended 124 Route Optimization (AERO) [RFC6706BIS]). In addition, ISO has 125 approved a standard specifying the IPv6 network protocols and 126 services to be used for Communications Access for Land Mobiles (CALM) 127 [ISO-ITS-IPv6] [ISO-ITS-IPv6-AMD1]. 129 This document describes use cases and a problem statement about 130 IPv6-based vehicular networking for ITS, which is named IPv6 Wireless 131 Access in Vehicular Environments (IPWAVE). First, it introduces the 132 use cases for using V2V, V2I, and V2X networking in ITS. Next, for 133 IPv6-based vehicular networks, it makes a gap analysis of current 134 IPv6 protocols (e.g., IPv6 Neighbor Discovery, Mobility Management, 135 and Security & Privacy), and then lists up requirements for the 136 extensions of those IPv6 protocols, which are tailored to IPv6-based 137 vehicular networking. Thus, this document is intended to motivate 138 development of key protocols for IPWAVE. 140 2. Terminology 142 This document uses the terminology described in [RFC8691]. In 143 addition, the following terms are defined below: 145 o Class-Based Safety Plan: A vehicle can make a safety plan by 146 classifying the surrounding vehicles into different groups for 147 safety purposes according to the geometrical relationship among 148 them. The vehicle groups can be classified as Line-of-Sight 149 Unsafe, Non-Line-of-Sight Unsafe, and Safe groups [CASD]. 151 o Context-Awareness: A vehicle can be aware of spatial-temporal 152 mobility information (e.g., position, speed, direction, and 153 acceleration/deceleration) of surrounding vehicles for both safety 154 and non-safety uses through sensing or communication [CASD]. 156 o DMM: "Distributed Mobility Management" [RFC7333][RFC7429]. 158 o Edge Computing (EC): It is the local computing near an access 159 network (i.e., edge network) for the sake of vehicles and 160 pedestrians. 162 o Edge Computing Device (ECD): It is a computing device (or server) 163 for edge computing for the sake of vehicles and pedestrians. 165 o Edge Network (EN): It is an access network that has an IP-RSU for 166 wireless communication with other vehicles having an IP-OBU and 167 wired communication with other network devices (e.g., routers, IP- 168 RSUs, ECDs, servers, and MA). It may have a Global Positioning 169 System (GPS) radio receiver for its position recognition and the 170 localization service for the sake of vehicles. 172 o IP-OBU: "Internet Protocol On-Board Unit": An IP-OBU denotes a 173 computer situated in a vehicle (e.g., car, bicycle, autobike, 174 motor cycle, and a similar one) and a device (e.g., smartphone and 175 IoT device). It has at least one IP interface that runs in IEEE 176 802.11-OCB and has an "OBU" transceiver. Also, it may have an IP 177 interface that runs in Cellular V2X (C-V2X) [TS-23.285-3GPP] 178 [TR-22.886-3GPP][TS-23.287-3GPP]. See the definition of the term 179 "OBU" in [RFC8691]. 181 o IP-RSU: "IP Roadside Unit": An IP-RSU is situated along the road. 182 It has at least two distinct IP-enabled interfaces. The wireless 183 PHY/MAC layer of at least one of its IP-enabled interfaces is 184 configured to operate in 802.11-OCB mode. An IP-RSU communicates 185 with the IP-OBU over an 802.11 wireless link operating in OCB 186 mode. Also, it may have an IP interface that runs in C-V2X along 187 with an "RSU" transceiver. An IP-RSU is similar to an Access 188 Network Router (ANR), defined in [RFC3753], and a Wireless 189 Termination Point (WTP), defined in [RFC5415]. See the definition 190 of the term "RSU" in [RFC8691]. 192 o LiDAR: "Light Detection and Ranging". It is a scanning device to 193 measure a distance to an object by emitting pulsed laser light and 194 measuring the reflected pulsed light. 196 o Mobility Anchor (MA): A node that maintains IPv6 addresses and 197 mobility information of vehicles in a road network to support 198 their IPv6 address autoconfiguration and mobility management with 199 a binding table. An MA has End-to-End (E2E) connections (e.g., 200 tunnels) with IP-RSUs under its control for the address 201 autoconfiguration and mobility management of the vehicles. This 202 MA is similar to a Local Mobility Anchor (LMA) in PMIPv6 [RFC5213] 203 for network-based mobility management. 205 o OCB: "Outside the Context of a Basic Service Set - BSS". It is a 206 mode of operation in which a Station (STA) is not a member of a 207 BSS and does not utilize IEEE Std 802.11 authentication, 208 association, or data confidentiality [IEEE-802.11-OCB]. 210 o 802.11-OCB: It refers to the mode specified in IEEE Std 211 802.11-2016 [IEEE-802.11-OCB] when the MIB attribute 212 dot11OCBActivited is 'true'. 214 o Platooning: Moving vehicles can be grouped together to reduce air- 215 resistance for energy efficiency and reduce the number of drivers 216 such that only the leading vehicle has a driver, and the other 217 vehicles are autonomous vehicles without a driver and closely 218 follow the leading vehicle [Truck-Platooning]. 220 o Traffic Control Center (TCC): A system that manages road 221 infrastructure nodes (e.g., IP-RSUs, MAs, traffic signals, and 222 loop detectors), and also maintains vehicular traffic statistics 223 (e.g., average vehicle speed and vehicle inter-arrival time per 224 road segment) and vehicle information (e.g., a vehicle's 225 identifier, position, direction, speed, and trajectory as a 226 navigation path). TCC is part of a vehicular cloud for vehicular 227 networks. 229 o Vehicle: A Vehicle in this document is a node that has an IP-OBU 230 for wireless communication with other vehicles and IP-RSUs. It 231 has a GPS radio navigation receiver for efficient navigation. Any 232 device having an IP-OBU and a GPS receiver (e.g., smartphone and 233 table PC) can be regarded as a vehicle in this document. 235 o Vehicular Ad Hoc Network (VANET): A network that consists of 236 vehicles interconnected by wireless communication. Two vehicles 237 in a VANET can communicate with each other using other vehicles as 238 relays even where they are out of one-hop wireless communication 239 range. 241 o Vehicular Cloud: A cloud infrastructure for vehicular networks, 242 having compute nodes, storage nodes, and network forwarding 243 elements (e.g., switch and router). 245 o V2D: "Vehicle to Device". It is the wireless communication 246 between a vehicle and a device (e.g., smartphone and IoT device). 248 o V2I2D: "Vehicle to Infrastructure to Device". It is the wireless 249 communication between a vehicle and a device (e.g., smartphone and 250 IoT device) via an infrastructure node (e.g., IP-RSU). 252 o V2I2V: "Vehicle to Infrastructure to Vehicle". It is the wireless 253 communication between a vehicle and another vehicle via an 254 infrastructure node (e.g., IP-RSU). 256 o V2I2X: "Vehicle to Infrastructure to Everything". It is the 257 wireless communication between a vehicle and another entity (e.g., 258 vehicle, smartphone, and IoT device) via an infrastructure node 259 (e.g., IP-RSU). 261 o V2X: "Vehicle to Everything". It is the wireless communication 262 between a vehicle and any entity (e.g., vehicle, infrastructure 263 node, smartphone, and IoT device), including V2V, V2I, and V2D. 265 o VIP: "Vehicular Internet Protocol". It is an IPv6 extension for 266 vehicular networks including V2V, V2I, and V2X. 268 o VMM: "Vehicular Mobility Management". It is an IPv6-based 269 mobility management for vehicular networks. 271 o VND: "Vehicular Neighbor Discovery". It is an IPv6 ND extension 272 for vehicular networks. 274 o VSP: "Vehicular Security and Privacy". It is an IPv6-based 275 security and privacy for vehicular networks. 277 o WAVE: "Wireless Access in Vehicular Environments" [WAVE-1609.0]. 279 3. Use Cases 281 This section explains use cases of V2V, V2I, and V2X networking. The 282 use cases of the V2X networking exclude the ones of the V2V and V2I 283 networking, but include Vehicle-to-Pedestrian (V2P) and Vehicle-to- 284 Device (V2D). 286 IP is widely used among popular end-user devices (e.g., smartphone 287 and tablet) in the Internet. Applications (e.g., navigator 288 application) for those devices can be extended such that the V2V use 289 cases in this section can work with IPv6 as a network layer protocol 290 and IEEE 802.11-OCB as a link layer protocol. In addition, IPv6 291 security needs to be extended to support those V2V use cases in a 292 safe, secure, privacy-preserving way. 294 The use cases presented in this section serve as the description and 295 motivation for the need to extend IPv6 and its protocols to 296 facilitate "Vehicular IPv6". Section 5 summarizes the overall 297 problem statement and IPv6 requirements. Note that the adjective 298 "Vehicular" in this document is used to represent extensions of 299 existing protocols such as IPv6 Neighbor Discovery, IPv6 Mobility 300 Management (e.g., PMIPv6 [RFC5213] and DMM [RFC7429]), and IPv6 301 Security and Privacy Mechanisms rather than new "vehicular-specific" 302 functions. Refer to Section 5 for the problem statement of the 303 requirements of vehicular IPv6. 305 3.1. V2V 307 The use cases of V2V networking discussed in this section include 309 o Context-aware navigation for safe driving and collision avoidance; 311 o Cooperative adaptive cruise control in a roadway; 313 o Platooning in a highway; 315 o Cooperative environment sensing; 317 o Collision avoidance service of end systems of Urban Air Mobility 318 (UAM). 320 These five techniques will be important elements for autonomous 321 vehicles, which may be either terrestrial vehicles or UAM end 322 systems. 324 Context-Aware Safety Driving (CASD) navigator [CASD] can help drivers 325 to drive safely by alerting them to dangerous obstacles and 326 situations. That is, a CASD navigator displays obstacles or 327 neighboring vehicles relevant to possible collisions in real-time 328 through V2V networking. CASD provides vehicles with a class-based 329 automatic safety action plan, which considers three situations, 330 namely, the Line-of-Sight unsafe, Non-Line-of-Sight unsafe, and safe 331 situations. This action plan can be put into action among multiple 332 vehicles using V2V networking. 334 Cooperative Adaptive Cruise Control (CACC) [CA-Cruise-Control] helps 335 individual vehicles to adapt their speed autonomously through V2V 336 communication among vehicles according to the mobility of their 337 predecessor and successor vehicles in an urban roadway or a highway. 338 Thus, CACC can help adjacent vehicles to efficiently adjust their 339 speed in an interactive way through V2V networking in order to avoid 340 a collision. 342 Platooning [Truck-Platooning] allows a series (or group) of vehicles 343 (e.g., trucks) to follow each other very closely. Trucks can use V2V 344 communication in addition to forward sensors in order to maintain 345 constant clearance between two consecutive vehicles at very short 346 gaps (from 3 meters to 10 meters). Platooning can maximize the 347 throughput of vehicular traffic in a highway and reduce the gas 348 consumption because the leading vehicle can help the following 349 vehicles to experience less air resistance. 351 Cooperative-environment-sensing use cases suggest that vehicles can 352 share environmental information (e.g., air pollution, hazards/ 353 obstacles, slippery areas by snow or rain, road accidents, traffic 354 congestion, and driving behaviors of neighboring vehicles) from 355 various vehicle-mounted sensors, such as radars, LiDARs, and cameras, 356 with other vehicles and pedestrians. [Automotive-Sensing] introduces 357 millimeter-wave vehicular communication for massive automotive 358 sensing. A lot of data can be generated by those sensors, and these 359 data typically need to be routed to different destinations. In 360 addition, from the perspective of driverless vehicles, it is expected 361 that driverless vehicles can be mixed with driver-operated vehicles. 362 Through cooperative environment sensing, driver-operated vehicles can 363 use environmental information sensed by driverless vehicles for 364 better interaction with the other vehicles and environment. Vehicles 365 can also share their intended maneuvering information (e.g., lane 366 change, speed change, ramp in-and-out, cut-in, and abrupt braking) 367 with neighboring vehicles. Thus, this information sharing can help 368 the vehicles behave as more efficient traffic flows and minimize 369 unnecessary acceleration and deceleration to achieve the best ride 370 comfort. 372 A collision avoidance service of UAM end systems in air can be 373 envisioned as a use case in air vehicular environments. This use 374 case is similar to the context-aware navigator for terrestrial 375 vehicles. Through V2V coordination, those UAM end systems (e.g., 376 drones) can avoid a dangerous situation (e.g., collision) in three- 377 dimensional space rather than two-dimensional space for terrestrial 378 vehicles. Also, UAM end systems (e.g., flying car) with only a few 379 meters off the ground can communicate with terrestrial vehicles with 380 wireless communication technologies (e.g., DSRC, LTE, and C-V2X). 381 Thus, V2V means any vehicle to any vehicle, whether the vehicles are 382 ground-level or not. 384 To encourage more vehicles to participate in this cooperative 385 environmental sensing, a reward system will be needed. Sensing 386 activities of each vehicle need to be logged in either a central way 387 through a logging server (e.g., TCC) in the vehicular cloud or a 388 distributed way (e.g., blockchain [Bitcoin]) through other vehicles 389 or infrastructure. In the case of a blockchain, each sensing message 390 from a vehicle can be treated as a transaction and the neighboring 391 vehicles can play the role of peers in a consensus method of a 392 blockchain [Bitcoin][Vehicular-BlockChain]. 394 The existing IPv6 protocol does not support wireless single-hop V2V 395 communications as well as wireless multihop V2V communications. 396 Thus, the IPv6 needs to support both single-hop and multihop 397 communications in a wireless medium so that vehicles can communicate 398 with each other by V2V communications to share either an emergency 399 situation or road hazard in a highway. 401 To support applications of these V2V use cases, the functions of IPv6 402 such as VND and VSP are prerequisites for IPv6-based packet exchange 403 and secure, safe communication between two vehicles. 405 3.2. V2I 407 The use cases of V2I networking discussed in this section include 409 o Navigation service; 411 o Energy-efficient speed recommendation service; 413 o Accident notification service; 415 o Electric vehicle (EV) charging service; 417 o UAM navigation service with efficient battery charging. 419 A navigation service, for example, the Self-Adaptive Interactive 420 Navigation Tool(SAINT) [SAINT], using V2I networking interacts with a 421 TCC for the large-scale/long-range road traffic optimization and can 422 guide individual vehicles along appropriate navigation paths in real 423 time. The enhanced version of SAINT [SAINTplus] can give fast moving 424 paths to emergency vehicles (e.g., ambulance and fire engine) to let 425 them reach an accident spot while redirecting other vehicles near the 426 accident spot into efficient detour paths. 428 Either a TCC or an ECD can recommend an energy-efficient speed to a 429 vehicle that depends on its traffic environment and traffic signal 430 scheduling [SignalGuru]. For example, when a vehicle approaches an 431 intersection area and a red traffic light for the vehicle becomes 432 turned on, it needs to reduce its speed to save fuel consumption. In 433 this case, either a TCC or an ECD, which has the up-to-date 434 trajectory of the vehicle and the traffic light schedule, can notify 435 the vehicle of an appropriate speed for fuel efficiency. 436 [Fuel-Efficient] studies fuel-efficient route and speed plans for 437 platooned trucks. 439 The emergency communication between accident vehicles (or emergency 440 vehicles) and a TCC can be performed via either IP-RSU or 4G-LTE 441 networks. The First Responder Network Authority (FirstNet) 442 [FirstNet] is provided by the US government to establish, operate, 443 and maintain an interoperable public safety broadband network for 444 safety and security network services, e.g., emergency calls. The 445 construction of the nationwide FirstNet network requires each state 446 in the US to have a Radio Access Network (RAN) that will connect to 447 the FirstNet's network core. The current RAN is mainly constructed 448 using 4G-LTE for the communication between a vehicle and an 449 infrastructure node (i.e., V2I) [FirstNet-Report], but it is expected 450 that DSRC-based vehicular networks [DSRC] will be available for V2I 451 and V2V in the near future. 453 An EV charging service with V2I can facilitates the efficient battery 454 charging of EVs. In the case where an EV charging station is 455 connected to an IP-RSU, an EV can be guided toward the deck of the EV 456 charging station through a battery charging server connected to the 457 IP-RSU. In addition to this EV charging service, other value-added 458 services (e.g., air firmware/software update and media streaming) can 459 be provided to an EV while it is charging its battery at the EV 460 charging station. 462 A UAM navigation service with efficient battery charging can make the 463 battery charging schedule of UAM end systems (e.g., drone) for long- 464 distance flying [CBDN]. For this battery charging schedule, a UAM 465 end system can communicate with an infrastructure node (e.g., IP-RSU) 466 toward a cloud server via V2I communications. This cloud server can 467 coordinate the battery charging schedules of multiple UAM end systems 468 for their efficient navigation path, considering flight time from 469 their current position to a battery charging station, waiting time in 470 a waiting queue at the station, and battery charging time at the 471 station. 473 The existing IPv6 protocol does not support wireless multihop V2I 474 communications in a highway where RSUs are sparsely deployed, so a 475 vehicle can reach the wireless coverage of an RSU through the 476 multihop data forwarding of intermediate vehicles. Thus, IPv6 needs 477 to be extended for multihop V2I communications. 479 To support applications of these V2I use cases, the functions of IPv6 480 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 481 exchange, transport-layer session continuity, and secure, safe 482 communication between a vehicle and a server in the vehicular cloud. 484 3.3. V2X 486 The use case of V2X networking discussed in this section is for a 487 pedestrian protection service. 489 A pedestrian protection service, such as Safety-Aware Navigation 490 Application (SANA) [SANA], using V2I2P networking can reduce the 491 collision of a vehicle and a pedestrian carrying a smartphone 492 equipped with a network device for wireless communication (e.g., Wi- 493 Fi) with an IP-RSU. Vehicles and pedestrians can also communicate 494 with each other via an IP-RSU. An edge computing device behind the 495 IP-RSU can collect the mobility information from vehicles and 496 pedestrians, compute wireless communication scheduling for the sake 497 of them. This scheduling can save the battery of each pedestrian's 498 smartphone by allowing it to work in sleeping mode before the 499 communication with vehicles, considering their mobility. 501 For Vehicle-to-Pedestrian (V2P), a vehicle can directly communicate 502 with a pedestrian's smartphone by V2X without IP-RSU relaying. 503 Light-weight mobile nodes such as bicycles may also communicate 504 directly with a vehicle for collision avoidance using V2V. 506 The existing IPv6 protocol does not support wireless multihop V2X (or 507 V2I2X) communications in an urban road network where RSUs are 508 deployed at intersections, so a vehicle (or a pedestrian's 509 smartphone) can reach the wireless coverage of an RSU through the 510 multihop data forwarding of intermediate vehicles (or pedestrians' 511 smartphones). Thus, IPv6 needs to be extended for multihop V2X (or 512 V2I2X) communications. 514 To support applications of these V2X use cases, the functions of IPv6 515 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 516 exchange, transport-layer session continuity, and secure, safe 517 communication between a vehicle and a pedestrian either directly or 518 indirectly via an IP-RSU. 520 4. Vehicular Networks 522 This section describes an example vehicular network architecture 523 supporting V2V, V2I, and V2X communications in vehicular networks. 524 It describes an internal network within a vehicle or an edge network 525 (called EN). It explains not only the internetworking between the 526 internal networks of a vehicle and an EN via wireless links, but also 527 the internetworking between the internal networks of two vehicles via 528 wireless links. 530 Traffic Control Center in Vehicular Cloud 531 ******************************************* 532 +-------------+ * * 533 |Corresponding| * +-----------------+ * 534 | Node |<->* | Mobility Anchor | * 535 +-------------+ * +-----------------+ * 536 * ^ * 537 * | * 538 * v * 539 ******************************************* 540 ^ ^ ^ 541 | | | 542 | | | 543 v v v 544 +---------+ +---------+ +---------+ 545 | IP-RSU1 |<--------->| IP-RSU2 |<--------->| IP-RSU3 | 546 +---------+ +---------+ +---------+ 547 ^ ^ ^ 548 : : : 549 +-----------------+ +-----------------+ +-----------------+ 550 | : V2I | | : V2I | | : V2I | 551 | v | | v | | v | 552 +--------+ | +--------+ | | +--------+ | | +--------+ | 553 |Vehicle1|===> |Vehicle2|===>| | |Vehicle3|===>| | |Vehicle4|===>| 554 +--------+<...>+--------+<........>+--------+ | | +--------+ | 555 V2V ^ V2V ^ | | ^ | 556 | : V2V | | : V2V | | : V2V | 557 | v | | v | | v | 558 | +--------+ | | +--------+ | | +--------+ | 559 | |Vehicle5|===> | | |Vehicle6|===>| | |Vehicle7|==>| 560 | +--------+ | | +--------+ | | +--------+ | 561 +-----------------+ +-----------------+ +-----------------+ 562 Subnet1 Subnet2 Subnet3 563 (Prefix1) (Prefix2) (Prefix3) 565 <----> Wired Link <....> Wireless Link ===> Moving Direction 567 Figure 1: An Example Vehicular Network Architecture for V2I and V2V 569 4.1. Vehicular Network Architecture 571 Figure 1 shows an example vehicular network architecture for V2I and 572 V2V in a road network [OMNI-Interface]. The vehicular network 573 architecture contains vehicles (including IP-OBU), IP-RSUs, Mobility 574 Anchor, Traffic Control Center, and Vehicular Cloud as components. 576 Note that the components of the vehicular network architecture can be 577 mapped to those of an IP-based aeronautical network architecture in 578 [OMNI-Interface], as shown in Figure 2. 580 +-------------------+------------------------------------+ 581 | Vehicular Network | Aeronautical Network | 582 +===================+====================================+ 583 | IP-RSU | Access Router (AR) | 584 +-------------------+------------------------------------+ 585 | Vehicle (IP-OBU) | Mobile Node (MN) | 586 +-------------------+------------------------------------+ 587 | Moving Network | End User Network (EUN) | 588 +-------------------+------------------------------------+ 589 | Mobility Anchor | Mobility Service Endpoint (MSE) | 590 +-------------------+------------------------------------+ 591 | Vehicular Cloud | Internetwork (INET) Routing System | 592 +-------------------+------------------------------------+ 594 Figure 2: Mapping between Vehicular Network Components and 595 Aeronautical Network Components 597 These components are not mandatory, and they can be deployed into 598 vehicular networks in various ways. Some of them (e.g., Mobility 599 Anchor, Traffic Control Center, and Vehicular Cloud) may not be 600 needed for the vehicular networks according to target use cases in 601 Section 3. 603 An existing network architecture (e.g., an IP-based aeronautical 604 network architecture [OMNI-Interface][UAM-ITS], a network 605 architecture of PMIPv6 [RFC5213], and a low-power and lossy network 606 architecture [RFC6550]) can be extended to a vehicular network 607 architecture for multihop V2V, V2I, and V2X, as shown in Figure 1. 608 In a highway scenario, a vehicle may not access an RSU directly 609 because of the distance of the DSRC coverage (up to 1 km). For 610 example, RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) 611 [RFC6550] can be extended to support a multihop V2I since a vehicle 612 can take advantage of other vehicles as relay nodes to reach the RSU. 613 Also, RPL can be extended to support both multihop V2V and V2X in the 614 similar way. 616 Wireless communications needs to be considered for end systems for 617 Urban Air Mobility (UAM) such as flying cars and taxis [UAM-ITS]. 618 These UAM end systems may have multiple wireless transmission media 619 interfaces (e.g., cellular, communications satellite (SATCOM), short- 620 range omni-directional interfaces), which are offered by different 621 data link service providers. To support not only the mobility 622 management of the UAM end systems, but also the multihop and 623 multilink communications of the UAM interfaces, the UAM end systems 624 can employ an Overlay Multilink Network (OMNI) interface 625 [OMNI-Interface] as a virtual Non-Broadcast Multiple Access (NBMA) 626 connection to a serving ground domain infrastructure. This 627 infrastructure can be configured over the underlying data links. The 628 OMNI interface and its link model provide a means of multilink, 629 multihop and mobility coordination to the legacy IPv6 ND messaging 630 [RFC4861] according to the NBMA principle. Thus, the OMNI link model 631 can support efficient UAM internetworking services without additional 632 mobility messaging, and without any modification to the IPv6 ND 633 messaging services or link model. 635 As shown in this figure, IP-RSUs as routers and vehicles with IP-OBU 636 have wireless media interfaces for VANET. Furthermore, the wireless 637 media interfaces are autoconfigured with a global IPv6 prefix (e.g., 638 2001:DB8:1:1::/64) to support both V2V and V2I networking. Note that 639 2001:DB8::/32 is a documentation prefix [RFC3849] for example 640 prefixes in this document, and also that any routable IPv6 address 641 needs to be routable in a VANET and a vehicular network including IP- 642 RSUs. 644 In Figure 1, three IP-RSUs (IP-RSU1, IP-RSU2, and IP-RSU3) are 645 deployed in the road network and are connected with each other 646 through the wired networks (e.g., Ethernet). A Traffic Control 647 Center (TCC) is connected to the Vehicular Cloud for the management 648 of IP-RSUs and vehicles in the road network. A Mobility Anchor (MA) 649 may be located in the TCC as a mobility management controller. 650 Vehicle2, Vehicle3, and Vehicle4 are wirelessly connected to IP-RSU1, 651 IP-RSU2, and IP-RSU3, respectively. The three wireless networks of 652 IP-RSU1, IP-RSU2, and IP-RSU3 can belong to three different subnets 653 (i.e., Subnet1, Subnet2, and Subnet3), respectively. Those three 654 subnets use three different prefixes (i.e., Prefix1, Prefix2, and 655 Prefix3). 657 Multiple vehicles under the coverage of an RSU share a prefix such 658 that mobile nodes share a prefix of a Wi-Fi access point in a 659 wireless LAN. This is a natural characteristic in infrastructure- 660 based wireless networks. For example, in Figure 1, two vehicles 661 (i.e., Vehicle2, and Vehicle5) can use Prefix 1 to configure their 662 IPv6 global addresses for V2I communication. 664 A single subnet prefix announced by an RSU can span multiple vehicles 665 in VANET. For example, in Figure 1, for Prefix 1, three vehicles 666 (i.e., Vehicle1, Vehicle2, and Vehicle5) can construct a connected 667 VANET. Also, for Prefix 2, two vehicles (i.e., Vehicle3 and 668 Vehicle6) can construct another connected VANET, and for Prefix 3, 669 two vehicles (i.e., Vehicle4 and Vehicle7) can construct another 670 connected VANET. 672 In wireless subnets in vehicular networks (e.g., Subnet1 and Subnet2 673 in Figure 1), vehicles can construct a connected VANET (with an 674 arbitrary graph topology) and can communicate with each other via V2V 675 communication. Vehicle1 can communicate with Vehicle2 via V2V 676 communication, and Vehicle2 can communicate with Vehicle3 via V2V 677 communication because they are within the wireless communication 678 range of each other. On the other hand, Vehicle3 can communicate 679 with Vehicle4 via the vehicular infrastructure (i.e., IP-RSU2 and IP- 680 RSU3) by employing V2I (i.e., V2I2V) communication because they are 681 not within the wireless communication range of each other. 683 For IPv6 packets transported over IEEE 802.11-OCB, [RFC8691] 684 specifies several details, including Maximum Transmission Unit (MTU), 685 frame format, link-local address, address mapping for unicast and 686 multicast, stateless autoconfiguration, and subnet structure. An 687 Ethernet Adaptation (EA) layer is in charge of transforming some 688 parameters between the IEEE 802.11 MAC layer and the IPv6 network 689 layer, which is located between the IEEE 802.11-OCB's logical link 690 control layer and the IPv6 network layer. This IPv6 over 802.11-OCB 691 can be used for both V2V and V2I in IPv6-based vehicular networks. 693 An IPv6 mobility solution is needed for the guarantee of 694 communication continuity in vehicular networks so that a vehicle's 695 TCP session can be continued, or UDP packets can be delivered to a 696 vehicle as a destination without loss while it moves from an IP-RSU's 697 wireless coverage to another IP-RSU's wireless coverage. In 698 Figure 1, assuming that Vehicle2 has a TCP session (or a UDP session) 699 with a corresponding node in the vehicular cloud, Vehicle2 can move 700 from IP-RSU1's wireless coverage to IP-RSU2's wireless coverage. In 701 this case, a handover for Vehicle2 needs to be performed by either a 702 host-based mobility management scheme (e.g., MIPv6 [RFC6275]) or a 703 network-based mobility management scheme (e.g., PMIPv6 [RFC5213]). 705 In the host-based mobility scheme (e.g., MIPv6), an IP-RSU plays a 706 role of a home agent. On the other hand, in the network-based 707 mobility scheme (e.g., PMIPv6, an MA plays a role of a mobility 708 management controller such as a Local Mobility Anchor (LMA) in 709 PMIPv6, which also serves vehicles as a home agent, and an IP-RSU 710 plays a role of an access router such as a Mobile Access Gateway 711 (MAG) in PMIPv6 [RFC5213]. The host-based mobility scheme needs 712 client functionality in IPv6 stack of a vehicle as a mobile node for 713 mobility signaling message exchange between the vehicle and home 714 agent. On the other hand, the network-based mobility scheme does not 715 need such a client functionality for a vehicle because the network 716 infrastructure node (e.g., MAG in PMIPv6) as a proxy mobility agent 717 handles the mobility signaling message exchange with the home agent 718 (e.g., LMA in PMIPv6) for the sake of the vehicle. 720 There are a scalability issue and a route optimization issue in the 721 network-based mobility scheme (e.g., PMIPv6) when an MA covers a 722 large vehicular network governing many IP-RSUs. In this case, a 723 distributed mobility scheme (e.g., DMM [RFC7429]) can mitigate the 724 scalability issue by distributing multiple MAs in the vehicular 725 network such that they are positioned closer to vehicles for route 726 optimization and bottleneck mitigation in a central MA in the 727 network-based mobility scheme. All these mobility approaches (i.e., 728 a host-based mobility scheme, network-based mobility scheme, and 729 distributed mobility scheme) and a hybrid approach of a combination 730 of them need to provide an efficient mobility service to vehicles 731 moving fast and moving along with the relatively predictable 732 trajectories along the roadways. 734 In vehicular networks, the control plane can be separated from the 735 data plane for efficient mobility management and data forwarding by 736 using the concept of Software-Defined Networking (SDN) 737 [RFC7149][DMM-FPC]. Note that Forwarding Policy Configuration (FPC) 738 in [DMM-FPC], which is a flexible mobility management system, can 739 manage the separation of data-plane and control-plane in DMM. In 740 SDN, the control plane and data plane are separated for the efficient 741 management of forwarding elements (e.g., switches and routers) where 742 an SDN controller configures the forwarding elements in a centralized 743 way and they perform packet forwarding according to their forwarding 744 tables that are configured by the SDN controller. An MA as an SDN 745 controller needs to efficiently configure and monitor its IP-RSUs and 746 vehicles for mobility management, location management, and security 747 services. 749 The mobility information of a GPS receiver mounted in its vehicle 750 (e.g., position, speed, and direction) can be used to accommodate 751 mobility-aware proactive handover schemes, which can perform the 752 handover of a vehicle according to its mobility and the wireless 753 signal strength of a vehicle and an IP-RSU in a proactive way. 755 Vehicles can use the TCC as their Home Network having a home agent 756 for mobility management as in MIPv6 [RFC6275] and PMIPv6 [RFC5213], 757 so the TCC (or an MA inside the TCC) maintains the mobility 758 information of vehicles for location management. IP tunneling over 759 the wireless link should be avoided for performance efficiency. 760 Also, in vehicular networks, asymmetric links sometimes exist and 761 must be considered for wireless communications such as V2V and V2I. 763 4.2. V2I-based Internetworking 765 This section discusses the internetworking between a vehicle's 766 internal network (i.e., moving network) and an EN's internal network 767 (i.e., fixed network) via V2I communication. The internal network of 768 a vehicle is nowadays constructed with Ethernet by many automotive 769 vendors [In-Car-Network]. Note that an EN can accommodate multiple 770 routers (or switches) and servers (e.g., ECDs, navigation server, and 771 DNS server) in its internal network. 773 A vehicle's internal network often uses Ethernet to interconnect 774 Electronic Control Units (ECUs) in the vehicle. The internal network 775 can support Wi-Fi and Bluetooth to accommodate a driver's and 776 passenger's mobile devices (e.g., smartphone or tablet). The network 777 topology and subnetting depend on each vendor's network configuration 778 for a vehicle and an EN. It is reasonable to consider the 779 interaction between the internal network and an external network 780 within another vehicle or an EN. 782 +-----------------+ 783 (*)<........>(*) +----->| Vehicular Cloud | 784 2001:DB8:1:1::/64 | | | +-----------------+ 785 +------------------------------+ +---------------------------------+ 786 | v | | v v | 787 | +-------+ +-------+ | | +-------+ +-------+ | 788 | | Host1 | |IP-OBU1| | | |IP-RSU1| | Host3 | | 789 | +-------+ +-------+ | | +-------+ +-------+ | 790 | ^ ^ | | ^ ^ | 791 | | | | | | | | 792 | v v | | v v | 793 | ---------------------------- | | ------------------------------- | 794 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:20:1::/64 | 795 | | | | | | 796 | v | | v | 797 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 798 | | Host2 | |Router1| | | |Router2| |Server1|...|ServerN| | 799 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 800 | ^ ^ | | ^ ^ ^ | 801 | | | | | | | | | 802 | v v | | v v v | 803 | ---------------------------- | | ------------------------------- | 804 | 2001:DB8:10:2::/64 | | 2001:DB8:20:2::/64 | 805 +------------------------------+ +---------------------------------+ 806 Vehicle1 (Moving Network1) EN1 (Fixed Network1) 808 <----> Wired Link <....> Wireless Link (*) Antenna 810 Figure 3: Internetworking between Vehicle and Edge Network 812 As shown in Figure 3, as internal networks, a vehicle's moving 813 network and an EN's fixed network are self-contained networks having 814 multiple subnets and having an edge router (e.g., IP-OBU and IP-RSU) 815 for the communication with another vehicle or another EN. The 816 internetworking between two internal networks via V2I communication 817 requires the exchange of the network parameters and the network 818 prefixes of the internal networks. For the efficiency, the network 819 prefixes of the internal networks (as a moving network) in a vehicle 820 need to be delegated and configured automatically. Note that a 821 moving network's network prefix can be called a Mobile Network Prefix 822 (MNP) [OMNI-Interface]. 824 Figure 3 also shows the internetworking between the vehicle's moving 825 network and the EN's fixed network. There exists an internal network 826 (Moving Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and 827 Host2), and two routers (IP-OBU1 and Router1). There exists another 828 internal network (Fixed Network1) inside EN1. EN1 has one host 829 (Host3), two routers (IP-RSU1 and Router2), and the collection of 830 servers (Server1 to ServerN) for various services in the road 831 networks, such as the emergency notification and navigation. 832 Vehicle1's IP-OBU1 (as a mobile router) and EN1's IP-RSU1 (as a fixed 833 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 834 V2I networking. Thus, a host (Host1) in Vehicle1 can communicate 835 with a server (Server1) in EN1 for a vehicular service through 836 Vehicle1's moving network, a wireless link between IP-OBU1 and IP- 837 RSU1, and EN1's fixed network. 839 For the IPv6 communication between an IP-OBU and an IP-RSU or between 840 two neighboring IP-OBUs, they need to know the network parameters, 841 which include MAC layer and IPv6 layer information. The MAC layer 842 information includes wireless link layer parameters, transmission 843 power level, and the MAC address of an external network interface for 844 the internetworking with another IP-OBU or IP-RSU. The IPv6 layer 845 information includes the IPv6 address and network prefix of an 846 external network interface for the internetworking with another IP- 847 OBU or IP-RSU. 849 Through the mutual knowledge of the network parameters of internal 850 networks, packets can be transmitted between the vehicle's moving 851 network and the EN's fixed network. Thus, V2I requires an efficient 852 protocol for the mutual knowledge of network parameters. 854 As shown in Figure 3, global IPv6 addresses are used for the wireless 855 link interfaces for IP-OBU and IP-RSU, but IPv6 Unique Local 856 Addresses (ULAs) [RFC4193] can also be used for those wireless link 857 interfaces as long as IPv6 packets can be routed to them in the 858 vehicular networks [OMNI-Interface]. For the guarantee of the 859 uniqueness of an IPv6 address, the configuration and control overhead 860 of the DAD of the wireless link interfaces should be minimized to 861 support the V2I and V2X communications of vehicles moving fast along 862 roadways. 864 4.3. V2V-based Internetworking 866 This section discusses the internetworking between the moving 867 networks of two neighboring vehicles via V2V communication. 869 (*)<..........>(*) 870 2001:DB8:1:1::/64 | | 871 +------------------------------+ +------------------------------+ 872 | v | | v | 873 | +-------+ +-------+ | | +-------+ +-------+ | 874 | | Host1 | |IP-OBU1| | | |IP-OBU2| | Host3 | | 875 | +-------+ +-------+ | | +-------+ +-------+ | 876 | ^ ^ | | ^ ^ | 877 | | | | | | | | 878 | v v | | v v | 879 | ---------------------------- | | ---------------------------- | 880 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:30:1::/64 | 881 | | | | | | 882 | v | | v | 883 | +-------+ +-------+ | | +-------+ +-------+ | 884 | | Host2 | |Router1| | | |Router2| | Host4 | | 885 | +-------+ +-------+ | | +-------+ +-------+ | 886 | ^ ^ | | ^ ^ | 887 | | | | | | | | 888 | v v | | v v | 889 | ---------------------------- | | ---------------------------- | 890 | 2001:DB8:10:2::/64 | | 2001:DB8:30:2::/64 | 891 +------------------------------+ +------------------------------+ 892 Vehicle1 (Moving Network1) Vehicle2 (Moving Network2) 894 <----> Wired Link <....> Wireless Link (*) Antenna 896 Figure 4: Internetworking between Two Vehicles 898 Figure 4 shows the internetworking between the moving networks of two 899 neighboring vehicles. There exists an internal network (Moving 900 Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and Host2), 901 and two routers (IP-OBU1 and Router1). There exists another internal 902 network (Moving Network2) inside Vehicle2. Vehicle2 has two hosts 903 (Host3 and Host4), and two routers (IP-OBU2 and Router2). Vehicle1's 904 IP-OBU1 (as a mobile router) and Vehicle2's IP-OBU2 (as a mobile 905 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 906 V2V networking. Thus, a host (Host1) in Vehicle1 can communicate 907 with another host (Host3) in Vehicle2 for a vehicular service through 908 Vehicle1's moving network, a wireless link between IP-OBU1 and IP- 909 OBU2, and Vehicle2's moving network. 911 As a V2V use case in Section 3.1, Figure 5 shows the linear network 912 topology of platooning vehicles for V2V communications where Vehicle3 913 is the leading vehicle with a driver, and Vehicle2 and Vehicle1 are 914 the following vehicles without drivers. 916 (*)<..................>(*)<..................>(*) 917 | | | 918 +-----------+ +-----------+ +-----------+ 919 | | | | | | 920 | +-------+ | | +-------+ | | +-------+ | 921 | |IP-OBU1| | | |IP-OBU2| | | |IP-OBU3| | 922 | +-------+ | | +-------+ | | +-------+ | 923 | ^ | | ^ | | ^ | 924 | | |=====> | | |=====> | | |=====> 925 | v | | v | | v | 926 | +-------+ | | +-------+ | | +-------+ | 927 | | Host1 | | | | Host2 | | | | Host3 | | 928 | +-------+ | | +-------+ | | +-------+ | 929 | | | | | | 930 +-----------+ +-----------+ +-----------+ 931 Vehicle1 Vehicle2 Vehicle3 933 <----> Wired Link <....> Wireless Link ===> Moving Direction 934 (*) Antenna 936 Figure 5: Multihop Internetworking between Two Vehicle Networks 938 As shown in Figure 5, multihop internetworking is feasible among the 939 moving networks of three vehicles in the same VANET. For example, 940 Host1 in Vehicle1 can communicate with Host3 in Vehicle3 via IP-OBU1 941 in Vehicle1, IP-OBU2 in Vehicle2, and IP-OBU3 in Vehicle3 in the 942 linear network, as shown in the figure. 944 5. Problem Statement 946 In order to specify protocols using the architecture mentioned in 947 Section 4.1, IPv6 core protocols have to be adapted to overcome 948 certain challenging aspects of vehicular networking. Since the 949 vehicles are likely to be moving at great speed, protocol exchanges 950 need to be completed in a time relatively short compared to the 951 lifetime of a link between a vehicle and an IP-RSU, or between two 952 vehicles. 954 Note that if two vehicles are moving in the opposite directions in a 955 roadway, the relative speed of this case is two times the relative 956 speed of a vehicle passing through an RSU. The time constraint of a 957 wireless link between two nodes needs to be considered because it may 958 affect the lifetime of a session involving the link. 960 The lifetime of a session varies depending on the session's type such 961 as a web surfing, voice call over IP, and DNS query. Regardless of a 962 session's type, to guide all the IPv6 packets to their destination 963 host, IP mobility should be supported for the session. 965 Thus, the time constraint of a wireless link has a major impact on 966 IPv6 Neighbor Discovery (ND). Mobility Management (MM) is also 967 vulnerable to disconnections that occur before the completion of 968 identity verification and tunnel management. This is especially true 969 given the unreliable nature of wireless communication. This section 970 presents key topics such as neighbor discovery and mobility 971 management. 973 5.1. Neighbor Discovery 975 IPv6 ND [RFC4861][RFC4862] is a core part of the IPv6 protocol suite. 976 IPv6 ND is designed for point-to-point links and transit links (e.g., 977 Ethernet). It assumes the efficient and reliable support of 978 multicast and unicast from the link layer for various network 979 operations such as MAC Address Resolution (AR), Duplicate Address 980 Detection (DAD), and Neighbor Unreachability Detection (NUD). 982 Vehicles move quickly within the communication coverage of any 983 particular vehicle or IP-RSU. Before the vehicles can exchange 984 application messages with each other, they need to be configured with 985 a link-local IPv6 address or a global IPv6 address, and run IPv6 ND. 987 The requirements for IPv6 ND for vehicular networks are efficient DAD 988 and NUD operations. An efficient DAD is required to reduce the 989 overhead of the DAD packets during a vehicle's travel in a road 990 network, which guaranteeing the uniqueness of a vehicle's global IPv6 991 address. An efficient NUD is required to reduce the overhead of the 992 NUD packets during a vehicle's travel in a road network, which 993 guaranteeing the accurate neighborhood information of a vehicle in 994 terms of adjacent vehicles and RSUs. 996 The legacy DAD assumes that a node with an IPv6 address can reach any 997 other node with the scope of its address at the time it claims its 998 address, and can hear any future claim for that address by another 999 party within the scope of its address for the duration of the address 1000 ownership. However, the partitioning and merging of VANETs makes 1001 this assumption frequently invalid in vehicular networks. The 1002 merging and partitioning of VANETs frequently occurs in vehicular 1003 networks. This merging and partitioning should be considered for the 1004 IPv6 ND such as IPv6 Stateless Address Autoconfiguration (SLAAC) 1005 [RFC4862]. Due to the merging of VANETs, two IPv6 addresses may 1006 conflict with each other though they were unique before the merging. 1007 Also, the partitioning of a VANET may make vehicles with the same 1008 prefix be physically unreachable. Also, SLAAC needs to prevent IPv6 1009 address duplication due to the merging of VANETs. According to the 1010 merging and partitioning, a destination vehicle (as an IPv6 host) 1011 needs to be distinguished as either an on-link host or an off-link 1012 host even though the source vehicle uses the same prefix as the 1013 destination vehicle. 1015 To efficiently prevent IPv6 address duplication due to the VANET 1016 partitioning and merging from happening in vehicular networks, the 1017 vehicular networks need to support a vehicular-network-wide DAD by 1018 defining a scope that is compatible with the legacy DAD. In this 1019 case, two vehicles can communicate with each other when there exists 1020 a communication path over VANET or a combination of VANETs and IP- 1021 RSUs, as shown in Figure 1. By using the vehicular-network-wide DAD, 1022 vehicles can assure that their IPv6 addresses are unique in the 1023 vehicular network whenever they are connected to the vehicular 1024 infrastructure or become disconnected from it in the form of VANET. 1026 ND time-related parameters such as router lifetime and Neighbor 1027 Advertisement (NA) interval need to be adjusted for vehicle speed and 1028 vehicle density. For example, the NA interval needs to be 1029 dynamically adjusted according to a vehicle's speed so that the 1030 vehicle can maintain its neighboring vehicles in a stable way, 1031 considering the collision probability with the NA messages sent by 1032 other vehicles. 1034 For IPv6-based safety applications (e.g., context-aware navigation, 1035 adaptive cruise control, and platooning) in vehicular networks, the 1036 delay-bounded data delivery is critical. IPv6 ND needs to work to 1037 support those IPv6-based safety applications efficiently. 1039 Thus, in IPv6-based vehicular networking, IPv6 ND should have minimum 1040 changes for the interoperability with the legacy IPv6 ND used in the 1041 Internet, including the DAD and NUD operations. 1043 5.1.1. Link Model 1045 A prefix model for a vehicular network needs to facilitate the 1046 communication between two vehicles with the same prefix regardless of 1047 the vehicular network topology as long as there exist bidirectional 1048 E2E paths between them in the vehicular network including VANETs and 1049 IP-RSUs. This prefix model allows vehicles with the same prefix to 1050 communicate with each other via a combination of multihop V2V and 1051 multihop V2I with VANETs and IP-RSUs. Note that the OMNI link model 1052 supports these multihop V2V and V2I through an OMNI multilink service 1053 [OMNI-Interface]. 1055 IPv6 protocols work under certain assumptions for the link model that 1056 do not necessarily hold in a vehicular wireless link 1057 [VIP-WAVE][RFC5889]. For instance, some IPv6 protocols assume 1058 symmetry in the connectivity among neighboring interfaces [RFC6250]. 1059 However, radio interference and different levels of transmission 1060 power may cause asymmetric links to appear in vehicular wireless 1061 links. As a result, a new vehicular link model needs to consider the 1062 asymmetry of dynamically changing vehicular wireless links. 1064 There is a relationship between a link and a prefix, besides the 1065 different scopes that are expected from the link-local and global 1066 types of IPv6 addresses. In an IPv6 link, it is assumed that all 1067 interfaces which are configured with the same subnet prefix and with 1068 on-link bit set can communicate with each other on an IPv6 link. 1069 However, the vehicular link model needs to define the relationship 1070 between a link and a prefix, considering the dynamics of wireless 1071 links and the characteristics of VANET. 1073 A VANET can have a single link between each vehicle pair within 1074 wireless communication range, as shown in Figure 5. When two 1075 vehicles belong to the same VANET, but they are out of wireless 1076 communication range, they cannot communicate directly with each 1077 other. Suppose that a global-scope IPv6 prefix (or an IPv6 ULA 1078 prefix) is assigned to VANETs in vehicular networks. Even though two 1079 vehicles in the same VANET configure their IPv6 addresses with the 1080 same IPv6 prefix, they may not communicate with each other not in one 1081 hop in the same VANET because of the multihop network connectivity 1082 between them. Thus, in this case, the concept of an on-link IPv6 1083 prefix does not hold because two vehicles with the same on-link IPv6 1084 prefix cannot communicate directly with each other. Also, when two 1085 vehicles are located in two different VANETs with the same IPv6 1086 prefix, they cannot communicate with each other. When these two 1087 VANETs converge to one VANET, the two vehicles can communicate with 1088 each other in a multihop fashion, for example, when they are Vehicle1 1089 and Vehicle3, as shown in Figure 5. 1091 From the previous observation, a vehicular link model should consider 1092 the frequent partitioning and merging of VANETs due to vehicle 1093 mobility. Therefore, the vehicular link model needs to use an on- 1094 link prefix and off-link prefix according to the network topology of 1095 vehicles such as a one-hop reachable network and a multihop reachable 1096 network (or partitioned networks). If the vehicles with the same 1097 prefix are reachable from each other in one hop, the prefix should be 1098 on-link. On the other hand, if some of the vehicles with the same 1099 prefix are not reachable from each other in one hop due to either the 1100 multihop topology in the VANET or multiple partitions, the prefix 1101 should be off-link. 1103 The vehicular link model needs to support multihop routing in a 1104 connected VANET where the vehicles with the same global-scope IPv6 1105 prefix (or the same IPv6 ULA prefix) are connected in one hop or 1106 multiple hops. It also needs to support the multihop routing in 1107 multiple connected VANETs through infrastructure nodes (e.g., IP-RSU) 1108 where they are connected to the infrastructure. For example, in 1109 Figure 1, suppose that Vehicle1, Vehicle2, and Vehicle3 are 1110 configured with their IPv6 addresses based on the same global-scope 1111 IPv6 prefix. Vehicle1 and Vehicle3 can also communicate with each 1112 other via either multihop V2V or multihop V2I2V. When Vehicle1 and 1113 Vehicle3 are connected in a VANET, it will be more efficient for them 1114 to communicate with each other directly via VANET rather than 1115 indirectly via IP-RSUs. On the other hand, when Vehicle1 and 1116 Vehicle3 are far away from direct communication range in separate 1117 VANETs and under two different IP-RSUs, they can communicate with 1118 each other through the relay of IP-RSUs via V2I2V. Thus, two 1119 separate VANETs can merge into one network via IP-RSU(s). Also, 1120 newly arriving vehicles can merge two separate VANETs into one VANET 1121 if they can play the role of a relay node for those VANETs. 1123 Thus, in IPv6-based vehicular networking, the vehicular link model 1124 should have minimum changes for the interoperability with the legacy 1125 IPv6 link model in an efficient fashion to support the IPv6 DAD and 1126 NUD operations. 1128 5.1.2. MAC Address Pseudonym 1130 For the protection of drivers' privacy, a pseudonym of a MAC address 1131 of a vehicle's network interface should be used, so that the MAC 1132 address can be changed periodically. However, although such a 1133 pseudonym of a MAC address can protect to some extent the privacy of 1134 a vehicle, it may not be able to resist attacks on vehicle 1135 identification by other fingerprint information, for example, the 1136 scrambler seed embedded in IEEE 802.11-OCB frames [Scrambler-Attack]. 1137 The pseudonym of a MAC address affects an IPv6 address based on the 1138 MAC address, and a transport-layer (e.g., TCP and SCTP) session with 1139 an IPv6 address pair. However, the pseudonym handling is not 1140 implemented and tested yet for applications on IP-based vehicular 1141 networking. 1143 In the ETSI standards, for the sake of security and privacy, an ITS 1144 station (e.g., vehicle) can use pseudonyms for its network interface 1145 identities (e.g., MAC address) and the corresponding IPv6 addresses 1146 [Identity-Management]. Whenever the network interface identifier 1147 changes, the IPv6 address based on the network interface identifier 1148 needs to be updated, and the uniqueness of the address needs to be 1149 checked through the DAD procedure. For vehicular networks with high 1150 mobility and density, this DAD needs to be performed efficiently with 1151 minimum overhead so that the vehicles can exchange application 1152 messages (e.g., collision avoidance and accident notification) with 1153 each other with a short interval (e.g., 0.5 second) 1154 [NHTSA-ACAS-Report]. 1156 5.1.3. Routing 1158 For multihop V2V communications in either a VANET or VANETs via IP- 1159 RSUs, a vehicular ad hoc routing protocol (e.g., AODV or OLSRv2) may 1160 be required to support both unicast and multicast in the links of the 1161 subnet with the same IPv6 prefix. However, it will be costly to run 1162 both vehicular ND and a vehicular ad hoc routing protocol in terms of 1163 control traffic overhead [ID-Multicast-Problems]. 1165 A routing protocol for a VANET may cause redundant wireless frames in 1166 the air to check the neighborhood of each vehicle and compute the 1167 routing information in a VANET with a dynamic network topology 1168 because the IPv6 ND is used to check the neighborhood of each 1169 vehicle. Thus, the vehicular routing needs to take advantage of the 1170 IPv6 ND to minimize its control overhead. 1172 5.2. Mobility Management 1174 The seamless connectivity and timely data exchange between two end 1175 points requires efficient mobility management including location 1176 management and handover. Most vehicles are equipped with a GPS 1177 receiver as part of a dedicated navigation system or a corresponding 1178 smartphone App. Note that the GPS receiver may not provide vehicles 1179 with accurate location information in adverse environments such as a 1180 building area or a tunnel. The location precision can be improved 1181 with assistance of the IP-RSUs or a cellular system with a GPS 1182 receiver for location information. 1184 With a GPS navigator, efficient mobility management can be performed 1185 with the help of vehicles periodically reporting their current 1186 position and trajectory (i.e., navigation path) to the vehicular 1187 infrastructure (having IP-RSUs and an MA in TCC). This vehicular 1188 infrastructure can predict the future positions of the vehicles from 1189 their mobility information (i.e., the current position, speed, 1190 direction, and trajectory) for efficient mobility management (e.g., 1191 proactive handover). For a better proactive handover, link-layer 1192 parameters, such as the signal strength of a link-layer frame (e.g., 1193 Received Channel Power Indicator (RCPI) [VIP-WAVE]), can be used to 1194 determine the moment of a handover between IP-RSUs along with 1195 mobility information. 1197 By predicting a vehicle's mobility, the vehicular infrastructure 1198 needs to better support IP-RSUs to perform efficient SLAAC, data 1199 forwarding, horizontal handover (i.e., handover in wireless links 1200 using a homogeneous radio technology), and vertical handover (i.e., 1201 handover in wireless links using heterogeneous radio technologies) in 1202 advance along with the movement of the vehicle. 1204 For example, as shown in Figure 1, when a vehicle (e.g., Vehicle2) is 1205 moving from the coverage of an IP-RSU (e.g., IP-RSU1) into the 1206 coverage of another IP-RSU (e.g., IP-RSU2) belonging to a different 1207 subnet, the IP-RSUs can proactively support the IPv6 mobility of the 1208 vehicle, while performing the SLAAC, data forwarding, and handover 1209 for the sake of the vehicle. 1211 For a mobility management scheme in a shared link, where the wireless 1212 subnets of multiple IP-RSUs share the same prefix, an efficient 1213 vehicular-network-wide DAD is required. If DHCPv6 is used to assign 1214 a unique IPv6 address to each vehicle in this shared link, the DAD is 1215 not required. On the other hand, for a mobility management scheme 1216 with a unique prefix per mobile node (e.g., PMIPv6 [RFC5213] and OMNI 1217 [OMNI-Interface]), DAD is not required because the IPv6 address of a 1218 vehicle's external wireless interface is guaranteed to be unique. 1219 There is a tradeoff between the prefix usage efficiency and DAD 1220 overhead. Thus, the IPv6 address autoconfiguration for vehicular 1221 networks needs to consider this tradeoff to support efficient 1222 mobility management. 1224 Therefore, for the proactive and seamless IPv6 mobility of vehicles, 1225 the vehicular infrastructure (including IP-RSUs and MA) needs to 1226 efficiently perform the mobility management of the vehicles with 1227 their mobility information and link-layer information. Also, in 1228 IPv6-based vehicular networking, IPv6 mobility management should have 1229 minimum changes for the interoperability with the legacy IPv6 1230 mobility management schemes such as PMIPv6, DMM, LISP, and AERO. 1232 6. Security Considerations 1234 This section discusses security and privacy for IPv6-based vehicular 1235 networking. Security and privacy are key components of IPv6-based 1236 vehicular networking along with neighbor discovery and mobility 1237 management. 1239 Security and privacy are paramount in V2I, V2V, and V2X networking. 1240 Vehicles and infrastructure must be authenticated in order to 1241 participate in vehicular networking. Also, in-vehicle devices (e.g., 1242 ECU) and a driver/passenger's mobile devices (e.g., smartphone and 1243 tablet PC) in a vehicle need to communicate with other in-vehicle 1244 devices and another driver/passenger's mobile devices in another 1245 vehicle, or other servers behind an IP-RSU in a secure way. Even 1246 though a vehicle is perfectly authenticated and legitimate, it may be 1247 hacked for running malicious applications to track and collect its 1248 and other vehicles' information. In this case, an attack mitigation 1249 process may be required to reduce the aftermath of malicious 1250 behaviors. 1252 Strong security measures shall protect vehicles roaming in road 1253 networks from the attacks of malicious nodes, which are controlled by 1254 hackers. For safe driving applications (e.g., context-aware 1255 navigation, cooperative adaptive cruise control, and platooning), as 1256 explained in Section 3.1, the cooperative action among vehicles is 1257 assumed. Malicious nodes may disseminate wrong driving information 1258 (e.g., location, speed, and direction) for disturbing safe driving. 1259 For example, a Sybil attack, which tries to confuse a vehicle with 1260 multiple false identities, may disturb a vehicle from taking a safe 1261 maneuver. 1263 Even though vehicles can be authenticated with valid certificates by 1264 an authentication server in the vehicular cloud, the authenticated 1265 vehicles may harm other vehicles, so their communication activities 1266 need to be logged in either a central way through a logging server 1267 (e.g., TCC) in the vehicular cloud or a distributed way (e.g., 1268 blockchain [Bitcoin]) along with other vehicles or infrastructure. 1269 For the non-repudiation of the harmful activities of malicious nodes, 1270 a blockchain technology can be used [Bitcoin]. Each message from a 1271 vehicle can be treated as a transaction and the neighboring vehicles 1272 can play the role of peers in a consensus method of a blockchain 1273 [Bitcoin][Vehicular-BlockChain]. For a blockchain's efficient 1274 consensus in vehicular networks having fast moving vehicles, a new 1275 consensus algorithm needs to be developed or an existing consensus 1276 algorithm needs to be enhanced. 1278 To identify malicious vehicles among vehicles, an authentication 1279 method is required. A Vehicle Identification Number (VIN) and a user 1280 certificate (e.g., X.509 certificate [RFC5280]) along with an in- 1281 vehicle device's identifier generation can be used to efficiently 1282 authenticate a vehicle or its driver (having a user certificate) 1283 through a road infrastructure node (e.g., IP-RSU) connected to an 1284 authentication server in the vehicular cloud. This authentication 1285 can be used to identify the vehicle that will communicate with an 1286 infrastructure node or another vehicle. In the case where a vehicle 1287 has an internal network (called Moving Network) and elements in the 1288 network (e.g., in-vehicle devices and a user's mobile devices), as 1289 shown in Figure 3, the elements in the network need to be 1290 authenticated individually for safe authentication. Also, Transport 1291 Layer Security (TLS) certificates [RFC8446][RFC5280] can be used for 1292 an element's authentication to allow secure E2E vehicular 1293 communications between an element in a vehicle and another element in 1294 a server in a vehicular cloud, or between an element in a vehicle and 1295 another element in another vehicle. 1297 For secure V2I communication, a secure channel (e.g., IPsec) between 1298 a mobile router (i.e., IP-OBU) in a vehicle and a fixed router (i.e., 1299 IP-RSU) in an EN needs to be established, as shown in Figure 3 1300 [RFC4301][RFC4302][RFC4303][RFC4308][RFC7296]. Also, for secure V2V 1301 communication, a secure channel (e.g., IPsec) between a mobile router 1302 (i.e., IP-OBU) in a vehicle and a mobile router (i.e., IP-OBU) in 1303 another vehicle needs to be established, as shown in Figure 4. For 1304 secure communication, an element in a vehicle (e.g., an in-vehicle 1305 device and a driver/passenger's mobile device) needs to establish a 1306 secure connection (e.g., TLS) with another element in another vehicle 1307 or another element in a vehicular cloud (e.g., a server). Even 1308 though IEEE 1609.2 [WAVE-1609.2] specifies security services for 1309 applications and management messages. This WAVE specification is 1310 optional, so if WAVE does not support the security of a WAVE frame, 1311 either the network layer or the transport layer needs to support 1312 security services for the WAVE frames. 1314 For the setup of a secure channel over IPsec or TLS, the multihop V2I 1315 communications over DSRC is required in a highway for the 1316 authentication by involving multiple intermediate vehicles as relay 1317 nodes toward an IP-RSU connected to an authentication server in the 1318 vehicular cloud. The V2I communications over 5G V2X (or LTE V2X) is 1319 required to allow a vehicle to communicate directly with a gNodeB (or 1320 eNodeB) connected to an authentication server in the vehicular cloud. 1322 To prevent an adversary from tracking a vehicle with its MAC address 1323 or IPv6 address, especially for a long-living transport-layer session 1324 (e.g., voice call over IP and video streaming service), a MAC address 1325 pseudonym needs to be provided to each vehicle; that is, each vehicle 1326 periodically updates its MAC address and its IPv6 address needs to be 1327 updated accordingly by the MAC address change [RFC4086][RFC4941]. 1328 Such an update of the MAC and IPv6 addresses should not interrupt the 1329 E2E communications between two vehicles (or between a vehicle and an 1330 IP-RSU) for a long-living transport-layer session. However, if this 1331 pseudonym is performed without strong E2E confidentiality (using 1332 either IPsec or TLS), there will be no privacy benefit from changing 1333 MAC and IPv6 addresses, because an adversary can observe the change 1334 of the MAC and IPv6 addresses and track the vehicle with those 1335 addresses. Thus, the MAC address pseudonym and the IPv6 address 1336 update should be performed with strong E2E confidentiality. 1338 For the IPv6 ND, the DAD is required to ensure the uniqueness of the 1339 IPv6 address of a vehicle's wireless interface. This DAD can be used 1340 as a flooding attack that uses the DAD-related ND packets 1341 disseminated over the VANET or vehicular networks. Thus, the 1342 vehicles and IP-RSUs need to filter out suspicious ND traffic in 1343 advance. 1345 For mobility management, a malicious vehicle can construct multiple 1346 virtual bogus vehicles, and register them with IP-RSUs and MA. This 1347 registration makes the IP-RSUs and MA waste their resources. The IP- 1348 RSUs and MA need to determine whether a vehicle is genuine or bogus 1349 in mobility management. Also, the confidentiality of control packets 1350 and data packets among IP-RSUs and MA, the E2E paths (e.g., tunnels) 1351 need to be protected by secure communication channels. In addition, 1352 to prevent bogus IP-RSUs and MA from interfering with the IPv6 1353 mobility of vehicles, mutual authentication among them needs to be 1354 performed by certificates (e.g., TLS certificate). 1356 7. Informative References 1358 [Automotive-Sensing] 1359 Choi, J., Va, V., Gonzalez-Prelcic, N., Daniels, R., R. 1360 Bhat, C., and R. W. Heath, "Millimeter-Wave Vehicular 1361 Communication to Support Massive Automotive Sensing", 1362 IEEE Communications Magazine, December 2016. 1364 [Bitcoin] Nakamoto, S., "Bitcoin: A Peer-to-Peer Electronic Cash 1365 System", URL: https://bitcoin.org/bitcoin.pdf, May 2009. 1367 [CA-Cruise-Control] 1368 California Partners for Advanced Transportation Technology 1369 (PATH), "Cooperative Adaptive Cruise Control", [Online] 1370 Available: 1371 http://www.path.berkeley.edu/research/automated-and- 1372 connected-vehicles/cooperative-adaptive-cruise-control, 1373 2017. 1375 [CASD] Shen, Y., Jeong, J., Oh, T., and S. Son, "CASD: A 1376 Framework of Context-Awareness Safety Driving in Vehicular 1377 Networks", International Workshop on Device Centric Cloud 1378 (DC2), March 2016. 1380 [CBDN] Kim, J., Kim, S., Jeong, J., Kim, H., Park, J., and T. 1381 Kim, "CBDN: Cloud-Based Drone Navigation for Efficient 1382 Battery Charging in Drone Networks", IEEE Transactions on 1383 Intelligent Transportation Systems, November 2019. 1385 [DMM-FPC] Matsushima, S., Bertz, L., Liebsch, M., Gundavelli, S., 1386 Moses, D., and C. Perkins, "Protocol for Forwarding Policy 1387 Configuration (FPC) in DMM", draft-ietf-dmm-fpc-cpdp-13 1388 (work in progress), March 2020. 1390 [DSRC] ASTM International, "Standard Specification for 1391 Telecommunications and Information Exchange Between 1392 Roadside and Vehicle Systems - 5 GHz Band Dedicated Short 1393 Range Communications (DSRC) Medium Access Control (MAC) 1394 and Physical Layer (PHY) Specifications", 1395 ASTM E2213-03(2010), October 2010. 1397 [EU-2008-671-EC] 1398 European Union, "Commission Decision of 5 August 2008 on 1399 the Harmonised Use of Radio Spectrum in the 5875 - 5905 1400 MHz Frequency Band for Safety-related Applications of 1401 Intelligent Transport Systems (ITS)", EU 2008/671/EC, 1402 August 2008. 1404 [FirstNet] 1405 U.S. National Telecommunications and Information 1406 Administration (NTIA), "First Responder Network Authority 1407 (FirstNet)", [Online] 1408 Available: https://www.firstnet.gov/, 2012. 1410 [FirstNet-Report] 1411 First Responder Network Authority, "FY 2017: ANNUAL REPORT 1412 TO CONGRESS, Advancing Public Safety Broadband 1413 Communications", FirstNet FY 2017, December 2017. 1415 [Fuel-Efficient] 1416 van de Hoef, S., H. Johansson, K., and D. V. Dimarogonas, 1417 "Fuel-Efficient En Route Formation of Truck Platoons", 1418 IEEE Transactions on Intelligent Transportation Systems, 1419 January 2018. 1421 [ID-Multicast-Problems] 1422 Perkins, C., McBride, M., Stanley, D., Kumari, W., and JC. 1423 Zuniga, "Multicast Considerations over IEEE 802 Wireless 1424 Media", draft-ietf-mboned-ieee802-mcast-problems-11 (work 1425 in progress), December 2019. 1427 [Identity-Management] 1428 Wetterwald, M., Hrizi, F., and P. Cataldi, "Cross-layer 1429 Identities Management in ITS Stations", The 10th 1430 International Conference on ITS Telecommunications, 1431 November 2010. 1433 [IEEE-802.11-OCB] 1434 "Part 11: Wireless LAN Medium Access Control (MAC) and 1435 Physical Layer (PHY) Specifications", IEEE Std 1436 802.11-2016, December 2016. 1438 [IEEE-802.11p] 1439 "Part 11: Wireless LAN Medium Access Control (MAC) and 1440 Physical Layer (PHY) Specifications - Amendment 6: 1441 Wireless Access in Vehicular Environments", IEEE Std 1442 802.11p-2010, June 2010. 1444 [In-Car-Network] 1445 Lim, H., Volker, L., and D. Herrscher, "Challenges in a 1446 Future IP/Ethernet-based In-Car Network for Real-Time 1447 Applications", ACM/EDAC/IEEE Design Automation Conference 1448 (DAC), June 2011. 1450 [ISO-ITS-IPv6] 1451 ISO/TC 204, "Intelligent Transport Systems - 1452 Communications Access for Land Mobiles (CALM) - IPv6 1453 Networking", ISO 21210:2012, June 2012. 1455 [ISO-ITS-IPv6-AMD1] 1456 ISO/TC 204, "Intelligent Transport Systems - 1457 Communications Access for Land Mobiles (CALM) - IPv6 1458 Networking - Amendment 1", ISO 21210:2012/AMD 1:2017, 1459 September 2017. 1461 [NHTSA-ACAS-Report] 1462 National Highway Traffic Safety Administration (NHTSA), 1463 "Final Report of Automotive Collision Avoidance Systems 1464 (ACAS) Program", DOT HS 809 080, August 2000. 1466 [OMNI-Interface] 1467 Templin, F. and A. Whyman, "Transmission of IPv6 Packets 1468 over Overlay Multilink Network (OMNI) Interfaces", draft- 1469 templin-6man-omni-interface-24 (work in progress), June 1470 2020. 1472 [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- 1473 Demand Distance Vector (AODV) Routing", RFC 3561, July 1474 2003. 1476 [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", 1477 RFC 3753, June 2004. 1479 [RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix 1480 Reserved for Documentation", RFC 3849, July 2004. 1482 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1483 "Randomness Requirements for Security", RFC 4086, June 1484 2005. 1486 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 1487 Addresses", RFC 4193, October 2005. 1489 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1490 Internet Protocol", RFC 4301, December 2005. 1492 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, December 1493 2005. 1495 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1496 RFC 4303, December 2005. 1498 [RFC4308] Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308, 1499 December 2005. 1501 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1502 "Neighbor Discovery for IP Version 6 (IPv6)", RFC 4861, 1503 September 2007. 1505 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1506 Address Autoconfiguration", RFC 4862, September 2007. 1508 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1509 Extensions for Stateless Address Autoconfiguration in 1510 IPv6", RFC 4941, September 2007. 1512 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1513 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1514 RFC 5213, August 2008. 1516 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1517 Housley, R., and W. Polk, "Internet X.509 Public Key 1518 Infrastructure Certificate and Certificate Revocation List 1519 (CRL) Profile", RFC 5280, May 2008. 1521 [RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And 1522 Provisioning of Wireless Access Points (CAPWAP) Protocol 1523 Specification", RFC 5415, March 2009. 1525 [RFC5889] Baccelli, E. and M. Townsley, "IP Addressing Model in Ad 1526 Hoc Networks", RFC 5889, September 2010. 1528 [RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250, May 1529 2011. 1531 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1532 Support in IPv6", RFC 6275, July 2011. 1534 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 1535 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 1536 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 1537 Lossy Networks", RFC 6550, March 2012. 1539 [RFC6706BIS] 1540 Templin, F., "Asymmetric Extended Route Optimization 1541 (AERO)", draft-templin-intarea-6706bis-58 (work in 1542 progress), June 2020. 1544 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 1545 "Neighbor Discovery Optimization for IPv6 over Low-Power 1546 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 1547 November 2012. 1549 [RFC6830BIS] 1550 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 1551 Cabellos, "The Locator/ID Separation Protocol (LISP)", 1552 draft-ietf-lisp-rfc6830bis-32 (work in progress), March 1553 2020. 1555 [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined 1556 Networking: A Perspective from within a Service Provider 1557 Environment", RFC 7149, March 2014. 1559 [RFC7181] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg, 1560 "The Optimized Link State Routing Protocol Version 2", 1561 RFC 7181, April 2014. 1563 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1564 Kivinen, "Internet Key Exchange Protocol Version 2 1565 (IKEv2)", RFC 7296, October 2014. 1567 [RFC7333] Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen, 1568 "Requirements for Distributed Mobility Management", 1569 RFC 7333, August 2014. 1571 [RFC7429] Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ. 1572 Bernardos, "Distributed Mobility Management: Current 1573 Practices and Gap Analysis", RFC 7429, January 2015. 1575 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1576 (IPv6) Specification", RFC 8200, July 2017. 1578 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 1579 Version 1.3", RFC 8446, August 2018. 1581 [RFC8691] Benamar, N., Haerri, J., Lee, J., and T. Ernst, "Basic 1582 Support for IPv6 Networks Operating Outside the Context of 1583 a Basic Service Set over IEEE Std 802.11", RFC 8691, 1584 December 2019. 1586 [SAINT] Jeong, J., Jeong, H., Lee, E., Oh, T., and D. Du, "SAINT: 1587 Self-Adaptive Interactive Navigation Tool for Cloud-Based 1588 Vehicular Traffic Optimization", IEEE Transactions on 1589 Vehicular Technology, Vol. 65, No. 6, June 2016. 1591 [SAINTplus] 1592 Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., and D. 1593 Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+ 1594 for Emergency Service Delivery Optimization", 1595 IEEE Transactions on Intelligent Transportation Systems, 1596 June 2017. 1598 [SANA] Hwang, T. and J. Jeong, "SANA: Safety-Aware Navigation 1599 Application for Pedestrian Protection in Vehicular 1600 Networks", Springer Lecture Notes in Computer Science 1601 (LNCS), Vol. 9502, December 2015. 1603 [Scrambler-Attack] 1604 Bloessl, B., Sommer, C., Dressier, F., and D. Eckhoff, 1605 "The Scrambler Attack: A Robust Physical Layer Attack on 1606 Location Privacy in Vehicular Networks", IEEE 2015 1607 International Conference on Computing, Networking and 1608 Communications (ICNC), February 2015. 1610 [SignalGuru] 1611 Koukoumidis, E., Peh, L., and M. Martonosi, "SignalGuru: 1612 Leveraging Mobile Phones for Collaborative Traffic Signal 1613 Schedule Advisory", ACM MobiSys, June 2011. 1615 [TR-22.886-3GPP] 1616 3GPP, "Study on Enhancement of 3GPP Support for 5G V2X 1617 Services", 3GPP TR 22.886/Version 16.2.0, December 2018. 1619 [Truck-Platooning] 1620 California Partners for Advanced Transportation Technology 1621 (PATH), "Automated Truck Platooning", [Online] Available: 1622 http://www.path.berkeley.edu/research/automated-and- 1623 connected-vehicles/truck-platooning, 2017. 1625 [TS-23.285-3GPP] 1626 3GPP, "Architecture Enhancements for V2X Services", 3GPP 1627 TS 23.285/Version 16.2.0, December 2019. 1629 [TS-23.287-3GPP] 1630 3GPP, "Architecture Enhancements for 5G System (5GS) to 1631 Support Vehicle-to-Everything (V2X) Services", 3GPP 1632 TS 23.287/Version 16.2.0, March 2020. 1634 [UAM-ITS] Templin, F., "Urban Air Mobility Implications for 1635 Intelligent Transportation Systems", draft-templin-ipwave- 1636 uam-its-03 (work in progress), July 2020. 1638 [Vehicular-BlockChain] 1639 Dorri, A., Steger, M., Kanhere, S., and R. Jurdak, 1640 "BlockChain: A Distributed Solution to Automotive Security 1641 and Privacy", IEEE Communications Magazine, Vol. 55, No. 1642 12, December 2017. 1644 [VIP-WAVE] 1645 Cespedes, S., Lu, N., and X. Shen, "VIP-WAVE: On the 1646 Feasibility of IP Communications in 802.11p Vehicular 1647 Networks", IEEE Transactions on Intelligent Transportation 1648 Systems, vol. 14, no. 1, March 2013. 1650 [WAVE-1609.0] 1651 IEEE 1609 Working Group, "IEEE Guide for Wireless Access 1652 in Vehicular Environments (WAVE) - Architecture", IEEE Std 1653 1609.0-2013, March 2014. 1655 [WAVE-1609.2] 1656 IEEE 1609 Working Group, "IEEE Standard for Wireless 1657 Access in Vehicular Environments - Security Services for 1658 Applications and Management Messages", IEEE Std 1659 1609.2-2016, March 2016. 1661 [WAVE-1609.3] 1662 IEEE 1609 Working Group, "IEEE Standard for Wireless 1663 Access in Vehicular Environments (WAVE) - Networking 1664 Services", IEEE Std 1609.3-2016, April 2016. 1666 [WAVE-1609.4] 1667 IEEE 1609 Working Group, "IEEE Standard for Wireless 1668 Access in Vehicular Environments (WAVE) - Multi-Channel 1669 Operation", IEEE Std 1609.4-2016, March 2016. 1671 Appendix A. Changes from draft-ietf-ipwave-vehicular-networking-15 1673 The following changes are made from draft-ietf-ipwave-vehicular- 1674 networking-15: 1676 o This version is revised based on the further comments from the 1677 following reviewers: Fred L. Templin (The Boeing Company) and 1678 YongJoon Joe (LSware). 1680 o According to the comments from Fred L. Templin, in Section 3.1 1681 and Section 3.2, UAM (Urban Air Mobility) end systems are 1682 considered for new V2V and V2I use cases. 1684 o According to the comments from YongJoon Joe, in Section 3.1 and 1685 Section 6, the text about a consensus method of a blockchain in 1686 vehicular networks is revised such that a consensus algorithm 1687 needs to be efficient for fast moving vehicles. 1689 Appendix B. Acknowledgments 1691 This work was supported by Institute of Information & Communications 1692 Technology Planning & Evaluation (IITP) grant funded by the Korea 1693 MSIT (Ministry of Science and ICT) (R-20160222-002755, Cloud based 1694 Security Intelligence Technology Development for the Customized 1695 Security Service Provisioning). 1697 This work was supported in part by the MSIT (Ministry of Science and 1698 ICT), Korea, under the ITRC (Information Technology Research Center) 1699 support program (IITP-2019-2017-0-01633) supervised by the IITP 1700 (Institute for Information & communications Technology Promotion). 1702 This work was supported in part by the French research project 1703 DataTweet (ANR-13-INFR-0008) and in part by the HIGHTS project funded 1704 by the European Commission I (636537-H2020). 1706 Appendix C. Contributors 1708 This document is a group work of IPWAVE working group, greatly 1709 benefiting from inputs and texts by Rex Buddenberg (Naval 1710 Postgraduate School), Thierry Ernst (YoGoKo), Bokor Laszlo (Budapest 1711 University of Technology and Economics), Jose Santa Lozanoi 1712 (Universidad of Murcia), Richard Roy (MIT), Francois Simon (Pilot), 1713 Sri Gundavelli (Cisco), Erik Nordmark, Dirk von Hugo (Deutsche 1714 Telekom), Pascal Thubert (Cisco), Carlos Bernardos (UC3M), Russ 1715 Housley (Vigil Security), Suresh Krishnan (Kaloom), Nancy Cam-Winget 1716 (Cisco), Fred L. Templin (The Boeing Company), Jung-Soo Park (ETRI), 1717 Zeungil (Ben) Kim (Hyundai Motors), Kyoungjae Sun (Soongsil 1718 University), Zhiwei Yan (CNNIC), YongJoon Joe (LSware), and Peter E. 1719 Yee (Akayla). The authors sincerely appreciate their contributions. 1721 The following are co-authors of this document: 1723 Nabil Benamar 1724 Department of Computer Sciences 1725 High School of Technology of Meknes 1726 Moulay Ismail University 1727 Morocco 1729 Phone: +212 6 70 83 22 36 1730 EMail: benamar73@gmail.com 1732 Sandra Cespedes 1733 NIC Chile Research Labs 1734 Universidad de Chile 1735 Av. Blanco Encalada 1975 1736 Santiago 1737 Chile 1739 Phone: +56 2 29784093 1740 EMail: scespede@niclabs.cl 1742 Jerome Haerri 1743 Communication Systems Department 1744 EURECOM 1745 Sophia-Antipolis 1746 France 1748 Phone: +33 4 93 00 81 34 1749 EMail: jerome.haerri@eurecom.fr 1751 Dapeng Liu 1752 Alibaba 1753 Beijing, Beijing 100022 1754 China 1756 Phone: +86 13911788933 1757 EMail: max.ldp@alibaba-inc.com 1759 Tae (Tom) Oh 1760 Department of Information Sciences and Technologies 1761 Rochester Institute of Technology 1762 One Lomb Memorial Drive 1763 Rochester, NY 14623-5603 1764 USA 1766 Phone: +1 585 475 7642 1767 EMail: Tom.Oh@rit.edu 1769 Charles E. Perkins 1770 Futurewei Inc. 1771 2330 Central Expressway 1772 Santa Clara, CA 95050 1773 USA 1775 Phone: +1 408 330 4586 1776 EMail: charliep@computer.org 1778 Alexandre Petrescu 1779 CEA, LIST 1780 CEA Saclay 1781 Gif-sur-Yvette, Ile-de-France 91190 1782 France 1784 Phone: +33169089223 1785 EMail: Alexandre.Petrescu@cea.fr 1787 Yiwen Chris Shen 1788 Department of Computer Science & Engineering 1789 Sungkyunkwan University 1790 2066 Seobu-Ro, Jangan-Gu 1791 Suwon, Gyeonggi-Do 16419 1792 Republic of Korea 1794 Phone: +82 31 299 4106 1795 Fax: +82 31 290 7996 1796 EMail: chrisshen@skku.edu 1797 URI: http://iotlab.skku.edu/people-chris-shen.php 1799 Michelle Wetterwald 1800 FBConsulting 1801 21, Route de Luxembourg 1802 Wasserbillig, Luxembourg L-6633 1803 Luxembourg 1804 EMail: Michelle.Wetterwald@gmail.com 1806 Author's Address 1808 Jaehoon Paul Jeong (editor) 1809 Department of Computer Science and Engineering 1810 Sungkyunkwan University 1811 2066 Seobu-Ro, Jangan-Gu 1812 Suwon, Gyeonggi-Do 16419 1813 Republic of Korea 1815 Phone: +82 31 299 4957 1816 Fax: +82 31 290 7996 1817 EMail: pauljeong@skku.edu 1818 URI: http://iotlab.skku.edu/people-jaehoon-jeong.php