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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 28, 2020 5 Expires: January 29, 2021 7 IPv6 Wireless Access in Vehicular Environments (IPWAVE): Problem 8 Statement and Use Cases 9 draft-ietf-ipwave-vehicular-networking-17 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 29, 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 . . . . . . . . . . . . . . . . . . . . . 12 66 4.1. Vehicular Network Architecture . . . . . . . . . . . . . 13 67 4.2. V2I-based Internetworking . . . . . . . . . . . . . . . . 17 68 4.3. V2V-based Internetworking . . . . . . . . . . . . . . . . 19 69 5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 21 70 5.1. Neighbor Discovery . . . . . . . . . . . . . . . . . . . 22 71 5.1.1. Link Model . . . . . . . . . . . . . . . . . . . . . 23 72 5.1.2. MAC Address Pseudonym . . . . . . . . . . . . . . . . 25 73 5.1.3. Routing . . . . . . . . . . . . . . . . . . . . . . . 26 74 5.2. Mobility Management . . . . . . . . . . . . . . . . . . . 26 75 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27 76 7. Informative References . . . . . . . . . . . . . . . . . . . 30 77 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 38 78 Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 38 79 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 40 81 1. Introduction 83 Vehicular networking studies have mainly focused on improving safety 84 and efficiency, and also enabling entertainment in vehicular 85 networks. The Federal Communications Commission (FCC) in the US 86 allocated wireless channels for Dedicated Short-Range Communications 87 (DSRC) [DSRC] in the Intelligent Transportation Systems (ITS) with 88 the frequency band of 5.850 - 5.925 GHz (i.e., 5.9 GHz band). DSRC- 89 based wireless communications can support vehicle-to-vehicle (V2V), 90 vehicle-to-infrastructure (V2I), and vehicle-to-everything (V2X) 91 networking. The European Union (EU) allocated radio spectrum for 92 safety-related and non-safety-related applications of ITS with the 93 frequency band of 5.875 - 5.905 GHz, as part of the Commission 94 Decision 2008/671/EC [EU-2008-671-EC]. 96 For direct inter-vehicular wireless connectivity, IEEE has amended 97 standard 802.11 (commonly known as Wi-Fi) to enable safe driving 98 services based on DSRC for the Wireless Access in Vehicular 99 Environments (WAVE) system. The Physical Layer (L1) and Data Link 100 Layer (L2) issues are addressed in IEEE 802.11p [IEEE-802.11p] for 101 the PHY and MAC of the DSRC, while IEEE 1609.2 [WAVE-1609.2] covers 102 security aspects, IEEE 1609.3 [WAVE-1609.3] defines related services 103 at network and transport layers, and IEEE 1609.4 [WAVE-1609.4] 104 specifies the multi-channel operation. IEEE 802.11p was first a 105 separate amendment, but was later rolled into the base 802.11 106 standard (IEEE 802.11-2012) as IEEE 802.11 Outside the Context of a 107 Basic Service Set (OCB) in 2012 [IEEE-802.11-OCB]. 109 3GPP has standardized Cellular Vehicle-to-Everything (C-V2X) 110 communications to support V2X in LTE mobile networks (called LTE V2X) 111 and V2X in 5G mobile networks (called 5G V2X) [TS-23.285-3GPP] 112 [TR-22.886-3GPP][TS-23.287-3GPP]. With C-V2X, vehicles can directly 113 communicate with each other without relay nodes (e.g., eNodeB in LTE 114 and gNodeB in 5G). 116 Along with these WAVE standards and C-V2X standards, regardless of a 117 wireless access technology under the IP stack of a vehicle, vehicular 118 networks can operate IP mobility with IPv6 [RFC8200] and Mobile IPv6 119 protocols (e.g., Mobile IPv6 (MIPv6) [RFC6275], Proxy MIPv6 (PMIPv6) 120 [RFC5213], Distributed Mobility Management (DMM) [RFC7333], Locator/ 121 ID Separation Protocol (LISP) [RFC6830BIS], and Asymmetric Extended 122 Route Optimization (AERO) [RFC6706BIS]). In addition, ISO has 123 approved a standard specifying the IPv6 network protocols and 124 services to be used for Communications Access for Land Mobiles (CALM) 125 [ISO-ITS-IPv6] [ISO-ITS-IPv6-AMD1]. 127 This document describes use cases and a problem statement about 128 IPv6-based vehicular networking for ITS, which is named IPv6 Wireless 129 Access in Vehicular Environments (IPWAVE). First, it introduces the 130 use cases for using V2V, V2I, and V2X networking in ITS. Next, for 131 IPv6-based vehicular networks, it makes a gap analysis of current 132 IPv6 protocols (e.g., IPv6 Neighbor Discovery, Mobility Management, 133 and Security & Privacy), and then lists up requirements for the 134 extensions of those IPv6 protocols, which are tailored to IPv6-based 135 vehicular networking. Thus, this document is intended to motivate 136 development of key protocols for IPWAVE. 138 2. Terminology 140 This document uses the terminology described in [RFC8691]. In 141 addition, the following terms are defined below: 143 o Class-Based Safety Plan: A vehicle can make a safety plan by 144 classifying the surrounding vehicles into different groups for 145 safety purposes according to the geometrical relationship among 146 them. The vehicle groups can be classified as Line-of-Sight 147 Unsafe, Non-Line-of-Sight Unsafe, and Safe groups [CASD]. 149 o Context-Awareness: A vehicle can be aware of spatial-temporal 150 mobility information (e.g., position, speed, direction, and 151 acceleration/deceleration) of surrounding vehicles for both safety 152 and non-safety uses through sensing or communication [CASD]. 154 o DMM: "Distributed Mobility Management" [RFC7333][RFC7429]. 156 o Edge Computing (EC): It is the local computing near an access 157 network (i.e., edge network) for the sake of vehicles and 158 pedestrians. 160 o Edge Computing Device (ECD): It is a computing device (or server) 161 for edge computing for the sake of vehicles and pedestrians. 163 o Edge Network (EN): It is an access network that has an IP-RSU for 164 wireless communication with other vehicles having an IP-OBU and 165 wired communication with other network devices (e.g., routers, IP- 166 RSUs, ECDs, servers, and MA). It may have a Global Positioning 167 System (GPS) radio receiver for its position recognition and the 168 localization service for the sake of vehicles. 170 o IP-OBU: "Internet Protocol On-Board Unit": An IP-OBU denotes a 171 computer situated in a vehicle (e.g., car, bicycle, autobike, 172 motor cycle, and a similar one) and a device (e.g., smartphone and 173 IoT device). It has at least one IP interface that runs in IEEE 174 802.11-OCB and has an "OBU" transceiver. Also, it may have an IP 175 interface that runs in Cellular V2X (C-V2X) [TS-23.285-3GPP] 176 [TR-22.886-3GPP][TS-23.287-3GPP]. See the definition of the term 177 "OBU" in [RFC8691]. 179 o IP-RSU: "IP Roadside Unit": An IP-RSU is situated along the road. 180 It has at least two distinct IP-enabled interfaces. The wireless 181 PHY/MAC layer of at least one of its IP-enabled interfaces is 182 configured to operate in 802.11-OCB mode. An IP-RSU communicates 183 with the IP-OBU over an 802.11 wireless link operating in OCB 184 mode. Also, it may have an IP interface that runs in C-V2X along 185 with an "RSU" transceiver. An IP-RSU is similar to an Access 186 Network Router (ANR), defined in [RFC3753], and a Wireless 187 Termination Point (WTP), defined in [RFC5415]. See the definition 188 of the term "RSU" in [RFC8691]. 190 o LiDAR: "Light Detection and Ranging". It is a scanning device to 191 measure a distance to an object by emitting pulsed laser light and 192 measuring the reflected pulsed light. 194 o Mobility Anchor (MA): A node that maintains IPv6 addresses and 195 mobility information of vehicles in a road network to support 196 their IPv6 address autoconfiguration and mobility management with 197 a binding table. An MA has End-to-End (E2E) connections (e.g., 198 tunnels) with IP-RSUs under its control for the address 199 autoconfiguration and mobility management of the vehicles. This 200 MA is similar to a Local Mobility Anchor (LMA) in PMIPv6 [RFC5213] 201 for network-based mobility management. 203 o OCB: "Outside the Context of a Basic Service Set - BSS". It is a 204 mode of operation in which a Station (STA) is not a member of a 205 BSS and does not utilize IEEE Std 802.11 authentication, 206 association, or data confidentiality [IEEE-802.11-OCB]. 208 o 802.11-OCB: It refers to the mode specified in IEEE Std 209 802.11-2016 [IEEE-802.11-OCB] when the MIB attribute 210 dot11OCBActivited is 'true'. 212 o Platooning: Moving vehicles can be grouped together to reduce air- 213 resistance for energy efficiency and reduce the number of drivers 214 such that only the leading vehicle has a driver, and the other 215 vehicles are autonomous vehicles without a driver and closely 216 follow the leading vehicle [Truck-Platooning]. 218 o Traffic Control Center (TCC): A system that manages road 219 infrastructure nodes (e.g., IP-RSUs, MAs, traffic signals, and 220 loop detectors), and also maintains vehicular traffic statistics 221 (e.g., average vehicle speed and vehicle inter-arrival time per 222 road segment) and vehicle information (e.g., a vehicle's 223 identifier, position, direction, speed, and trajectory as a 224 navigation path). TCC is part of a vehicular cloud for vehicular 225 networks. 227 o Vehicle: A Vehicle in this document is a node that has an IP-OBU 228 for wireless communication with other vehicles and IP-RSUs. It 229 has a GPS radio navigation receiver for efficient navigation. Any 230 device having an IP-OBU and a GPS receiver (e.g., smartphone and 231 table PC) can be regarded as a vehicle in this document. 233 o Vehicular Ad Hoc Network (VANET): A network that consists of 234 vehicles interconnected by wireless communication. Two vehicles 235 in a VANET can communicate with each other using other vehicles as 236 relays even where they are out of one-hop wireless communication 237 range. 239 o Vehicular Cloud: A cloud infrastructure for vehicular networks, 240 having compute nodes, storage nodes, and network forwarding 241 elements (e.g., switch and router). 243 o V2D: "Vehicle to Device". It is the wireless communication 244 between a vehicle and a device (e.g., smartphone and IoT device). 246 o V2I2D: "Vehicle to Infrastructure to Device". It is the wireless 247 communication between a vehicle and a device (e.g., smartphone and 248 IoT device) via an infrastructure node (e.g., IP-RSU). 250 o V2I2V: "Vehicle to Infrastructure to Vehicle". It is the wireless 251 communication between a vehicle and another vehicle via an 252 infrastructure node (e.g., IP-RSU). 254 o V2I2X: "Vehicle to Infrastructure to Everything". It is the 255 wireless communication between a vehicle and another entity (e.g., 256 vehicle, smartphone, and IoT device) via an infrastructure node 257 (e.g., IP-RSU). 259 o V2X: "Vehicle to Everything". It is the wireless communication 260 between a vehicle and any entity (e.g., vehicle, infrastructure 261 node, smartphone, and IoT device), including V2V, V2I, and V2D. 263 o VIP: "Vehicular Internet Protocol". It is an IPv6 extension for 264 vehicular networks including V2V, V2I, and V2X. 266 o VMM: "Vehicular Mobility Management". It is an IPv6-based 267 mobility management for vehicular networks. 269 o VND: "Vehicular Neighbor Discovery". It is an IPv6 ND extension 270 for vehicular networks. 272 o VSP: "Vehicular Security and Privacy". It is an IPv6-based 273 security and privacy for vehicular networks. 275 o WAVE: "Wireless Access in Vehicular Environments" [WAVE-1609.0]. 277 3. Use Cases 279 This section explains use cases of V2V, V2I, and V2X networking. The 280 use cases of the V2X networking exclude the ones of the V2V and V2I 281 networking, but include Vehicle-to-Pedestrian (V2P) and Vehicle-to- 282 Device (V2D). 284 IP is widely used among popular end-user devices (e.g., smartphone 285 and tablet) in the Internet. Applications (e.g., navigator 286 application) for those devices can be extended such that the V2V use 287 cases in this section can work with IPv6 as a network layer protocol 288 and IEEE 802.11-OCB as a link layer protocol. In addition, IPv6 289 security needs to be extended to support those V2V use cases in a 290 safe, secure, privacy-preserving way. 292 The use cases presented in this section serve as the description and 293 motivation for the need to extend IPv6 and its protocols to 294 facilitate "Vehicular IPv6". Section 5 summarizes the overall 295 problem statement and IPv6 requirements. Note that the adjective 296 "Vehicular" in this document is used to represent extensions of 297 existing protocols such as IPv6 Neighbor Discovery, IPv6 Mobility 298 Management (e.g., PMIPv6 [RFC5213] and DMM [RFC7429]), and IPv6 299 Security and Privacy Mechanisms rather than new "vehicular-specific" 300 functions. Refer to Section 5 for the problem statement of the 301 requirements of vehicular IPv6. 303 3.1. V2V 305 The use cases of V2V networking discussed in this section include 307 o Context-aware navigation for safe driving and collision avoidance; 309 o Cooperative adaptive cruise control in a roadway; 311 o Platooning in a highway; 313 o Cooperative environment sensing; 315 o Collision avoidance service of end systems of Urban Air Mobility 316 (UAM) [UAM-ITS]. 318 These five techniques will be important elements for autonomous 319 vehicles, which may be either terrestrial vehicles or UAM end 320 systems. 322 Context-Aware Safety Driving (CASD) navigator [CASD] can help drivers 323 to drive safely by alerting them to dangerous obstacles and 324 situations. That is, a CASD navigator displays obstacles or 325 neighboring vehicles relevant to possible collisions in real-time 326 through V2V networking. CASD provides vehicles with a class-based 327 automatic safety action plan, which considers three situations, 328 namely, the Line-of-Sight unsafe, Non-Line-of-Sight unsafe, and safe 329 situations. This action plan can be put into action among multiple 330 vehicles using V2V networking. 332 Cooperative Adaptive Cruise Control (CACC) [CA-Cruise-Control] helps 333 individual vehicles to adapt their speed autonomously through V2V 334 communication among vehicles according to the mobility of their 335 predecessor and successor vehicles in an urban roadway or a highway. 336 Thus, CACC can help adjacent vehicles to efficiently adjust their 337 speed in an interactive way through V2V networking in order to avoid 338 a collision. 340 Platooning [Truck-Platooning] allows a series (or group) of vehicles 341 (e.g., trucks) to follow each other very closely. Trucks can use V2V 342 communication in addition to forward sensors in order to maintain 343 constant clearance between two consecutive vehicles at very short 344 gaps (from 3 meters to 10 meters). Platooning can maximize the 345 throughput of vehicular traffic in a highway and reduce the gas 346 consumption because the leading vehicle can help the following 347 vehicles to experience less air resistance. 349 Cooperative-environment-sensing use cases suggest that vehicles can 350 share environmental information (e.g., air pollution, hazards/ 351 obstacles, slippery areas by snow or rain, road accidents, traffic 352 congestion, and driving behaviors of neighboring vehicles) from 353 various vehicle-mounted sensors, such as radars, LiDARs, and cameras, 354 with other vehicles and pedestrians. [Automotive-Sensing] introduces 355 millimeter-wave vehicular communication for massive automotive 356 sensing. A lot of data can be generated by those sensors, and these 357 data typically need to be routed to different destinations. In 358 addition, from the perspective of driverless vehicles, it is expected 359 that driverless vehicles can be mixed with driver-operated vehicles. 360 Through cooperative environment sensing, driver-operated vehicles can 361 use environmental information sensed by driverless vehicles for 362 better interaction with the other vehicles and environment. Vehicles 363 can also share their intended maneuvering information (e.g., lane 364 change, speed change, ramp in-and-out, cut-in, and abrupt braking) 365 with neighboring vehicles. Thus, this information sharing can help 366 the vehicles behave as more efficient traffic flows and minimize 367 unnecessary acceleration and deceleration to achieve the best ride 368 comfort. 370 A collision avoidance service of UAM end systems in air can be 371 envisioned as a use case in air vehicular environments. This use 372 case is similar to the context-aware navigator for terrestrial 373 vehicles. Through V2V coordination, those UAM end systems (e.g., 374 drones) can avoid a dangerous situation (e.g., collision) in three- 375 dimensional space rather than two-dimensional space for terrestrial 376 vehicles. Also, UAM end systems (e.g., flying car) with only a few 377 meters off the ground can communicate with terrestrial vehicles with 378 wireless communication technologies (e.g., DSRC, LTE, and C-V2X). 379 Thus, V2V means any vehicle to any vehicle, whether the vehicles are 380 ground-level or not. 382 To encourage more vehicles to participate in this cooperative 383 environmental sensing, a reward system will be needed. Sensing 384 activities of each vehicle need to be logged in either a central way 385 through a logging server (e.g., TCC) in the vehicular cloud or a 386 distributed way (e.g., blockchain [Bitcoin]) through other vehicles 387 or infrastructure. In the case of a blockchain, each sensing message 388 from a vehicle can be treated as a transaction and the neighboring 389 vehicles can play the role of peers in a consensus method of a 390 blockchain [Bitcoin][Vehicular-BlockChain]. 392 The existing IPv6 protocol must be augmented through the addition of 393 an Overlay Multilink Network (OMNI) Interface [OMNI] and/or protocol 394 changes in order to support wireless single-hop V2V communications as 395 well as wireless multihop V2V communications. Thus, the IPv6 needs 396 to support both single-hop and multihop communications in a wireless 397 medium so that vehicles can communicate with each other by V2V 398 communications to share either an emergency situation or road hazard 399 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 must be augmented through the addition of 474 an OMNI interface and/or protocol changes in order to support 475 wireless multihop V2I communications in a highway where RSUs are 476 sparsely deployed, so a vehicle can reach the wireless coverage of an 477 RSU through the multihop data forwarding of intermediate vehicles. 478 Thus, IPv6 needs to be extended for multihop V2I communications. 480 To support applications of these V2I use cases, the functions of IPv6 481 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 482 exchange, transport-layer session continuity, and secure, safe 483 communication between a vehicle and a server in the vehicular cloud. 485 3.3. V2X 487 The use case of V2X networking discussed in this section is for a 488 pedestrian protection service. 490 A pedestrian protection service, such as Safety-Aware Navigation 491 Application (SANA) [SANA], using V2I2P networking can reduce the 492 collision of a vehicle and a pedestrian carrying a smartphone 493 equipped with a network device for wireless communication (e.g., Wi- 494 Fi) with an IP-RSU. Vehicles and pedestrians can also communicate 495 with each other via an IP-RSU. An edge computing device behind the 496 IP-RSU can collect the mobility information from vehicles and 497 pedestrians, compute wireless communication scheduling for the sake 498 of them. This scheduling can save the battery of each pedestrian's 499 smartphone by allowing it to work in sleeping mode before the 500 communication with vehicles, considering their mobility. 502 For Vehicle-to-Pedestrian (V2P), a vehicle can directly communicate 503 with a pedestrian's smartphone by V2X without IP-RSU relaying. 504 Light-weight mobile nodes such as bicycles may also communicate 505 directly with a vehicle for collision avoidance using V2V. 507 The existing IPv6 protocol must be augmented through the addition of 508 an OMNI interface and/or protocol changes in order to support 509 wireless multihop V2X (or V2I2X) communications in an urban road 510 network where RSUs are deployed at intersections, so a vehicle (or a 511 pedestrian's smartphone) can reach the wireless coverage of an RSU 512 through the multihop data forwarding of intermediate vehicles (or 513 pedestrians' smartphones). Thus, IPv6 needs to be extended for 514 multihop V2X (or V2I2X) communications. 516 To support applications of these V2X use cases, the functions of IPv6 517 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 518 exchange, transport-layer session continuity, and secure, safe 519 communication between a vehicle and a pedestrian either directly or 520 indirectly via an IP-RSU. 522 4. Vehicular Networks 524 This section describes an example vehicular network architecture 525 supporting V2V, V2I, and V2X communications in vehicular networks. 526 It describes an internal network within a vehicle or an edge network 527 (called EN). It explains not only the internetworking between the 528 internal networks of a vehicle and an EN via wireless links, but also 529 the internetworking between the internal networks of two vehicles via 530 wireless links. 532 Traffic Control Center in Vehicular Cloud 533 ******************************************* 534 +-------------+ * * 535 |Corresponding| * +-----------------+ * 536 | Node |<->* | Mobility Anchor | * 537 +-------------+ * +-----------------+ * 538 * ^ * 539 * | * 540 * v * 541 ******************************************* 542 ^ ^ ^ 543 | | | 544 | | | 545 v v v 546 +---------+ +---------+ +---------+ 547 | IP-RSU1 |<--------->| IP-RSU2 |<--------->| IP-RSU3 | 548 +---------+ +---------+ +---------+ 549 ^ ^ ^ 550 : : : 551 +-----------------+ +-----------------+ +-----------------+ 552 | : V2I | | : V2I | | : V2I | 553 | v | | v | | v | 554 +--------+ | +--------+ | | +--------+ | | +--------+ | 555 |Vehicle1|===> |Vehicle2|===>| | |Vehicle3|===>| | |Vehicle4|===>| 556 +--------+<...>+--------+<........>+--------+ | | +--------+ | 557 V2V ^ V2V ^ | | ^ | 558 | : V2V | | : V2V | | : V2V | 559 | v | | v | | v | 560 | +--------+ | | +--------+ | | +--------+ | 561 | |Vehicle5|===> | | |Vehicle6|===>| | |Vehicle7|==>| 562 | +--------+ | | +--------+ | | +--------+ | 563 +-----------------+ +-----------------+ +-----------------+ 564 Subnet1 Subnet2 Subnet3 565 (Prefix1) (Prefix2) (Prefix3) 567 <----> Wired Link <....> Wireless Link ===> Moving Direction 569 Figure 1: An Example Vehicular Network Architecture for V2I and V2V 571 4.1. Vehicular Network Architecture 573 Figure 1 shows an example vehicular network architecture for V2I and 574 V2V in a road network [OMNI]. The vehicular network architecture 575 contains vehicles (including IP-OBU), IP-RSUs, Mobility Anchor, 576 Traffic Control Center, and Vehicular Cloud as components. Note that 577 the components of the vehicular network architecture can be mapped to 578 those of an IP-based aeronautical network architecture in [OMNI], as 579 shown in Figure 2. 581 +-------------------+------------------------------------+ 582 | Vehicular Network | Aeronautical Network | 583 +===================+====================================+ 584 | IP-RSU | Access Router (AR) | 585 +-------------------+------------------------------------+ 586 | Vehicle (IP-OBU) | Mobile Node (MN) | 587 +-------------------+------------------------------------+ 588 | Moving Network | End User Network (EUN) | 589 +-------------------+------------------------------------+ 590 | Mobility Anchor | Mobility Service Endpoint (MSE) | 591 +-------------------+------------------------------------+ 592 | Vehicular Cloud | Internetwork (INET) Routing System | 593 +-------------------+------------------------------------+ 595 Figure 2: Mapping between Vehicular Network Components and 596 Aeronautical Network Components 598 These components are not mandatory, and they can be deployed into 599 vehicular networks in various ways. Some of them (e.g., Mobility 600 Anchor, Traffic Control Center, and Vehicular Cloud) may not be 601 needed for the vehicular networks according to target use cases in 602 Section 3. 604 An existing network architecture (e.g., an IP-based aeronautical 605 network architecture [OMNI][UAM-ITS], a network architecture of 606 PMIPv6 [RFC5213], and a low-power and lossy network architecture 607 [RFC6550]) can be extended to a vehicular network architecture for 608 multihop V2V, V2I, and V2X, as shown in Figure 1. In a highway 609 scenario, a vehicle may not access an RSU directly because of the 610 distance of the DSRC coverage (up to 1 km). For example, the OMNI 611 interface and/or RPL (IPv6 Routing Protocol for Low-Power and Lossy 612 Networks) [RFC6550] can be extended to support a multihop V2I since a 613 vehicle can take advantage of other vehicles as relay nodes to reach 614 the RSU. Also, RPL can be extended to support both multihop V2V and 615 V2X in the similar way. 617 Wireless communications needs to be considered for end systems for 618 Urban Air Mobility (UAM) such as flying cars and taxis [UAM-ITS]. 620 These UAM end systems may have multiple wireless transmission media 621 interfaces (e.g., cellular, communications satellite (SATCOM), short- 622 range omni-directional interfaces), which are offered by different 623 data link service providers. To support not only the mobility 624 management of the UAM end systems, but also the multihop and 625 multilink communications of the UAM interfaces, the UAM end systems 626 can employ an Overlay Multilink Network (OMNI) interface [OMNI] as a 627 virtual Non-Broadcast Multiple Access (NBMA) connection to a serving 628 ground domain infrastructure. This infrastructure can be configured 629 over the underlying data links. The OMNI interface and its link 630 model provide a means of multilink, multihop and mobility 631 coordination to the legacy IPv6 ND messaging [RFC4861] according to 632 the NBMA principle. Thus, the OMNI link model can support efficient 633 UAM internetworking services without additional mobility messaging, 634 and without any modification to the IPv6 ND messaging services or 635 link model. 637 As shown in this figure, IP-RSUs as routers and vehicles with IP-OBU 638 have wireless media interfaces for VANET. Furthermore, the wireless 639 media interfaces are autoconfigured with a global IPv6 prefix (e.g., 640 2001:DB8:1:1::/64) to support both V2V and V2I networking. Note that 641 2001:DB8::/32 is a documentation prefix [RFC3849] for example 642 prefixes in this document, and also that any routable IPv6 address 643 needs to be routable in a VANET and a vehicular network including IP- 644 RSUs. 646 In Figure 1, three IP-RSUs (IP-RSU1, IP-RSU2, and IP-RSU3) are 647 deployed in the road network and are connected with each other 648 through the wired networks (e.g., Ethernet). A Traffic Control 649 Center (TCC) is connected to the Vehicular Cloud for the management 650 of IP-RSUs and vehicles in the road network. A Mobility Anchor (MA) 651 may be located in the TCC as a mobility management controller. 652 Vehicle2, Vehicle3, and Vehicle4 are wirelessly connected to IP-RSU1, 653 IP-RSU2, and IP-RSU3, respectively. The three wireless networks of 654 IP-RSU1, IP-RSU2, and IP-RSU3 can belong to three different subnets 655 (i.e., Subnet1, Subnet2, and Subnet3), respectively. Those three 656 subnets use three different prefixes (i.e., Prefix1, Prefix2, and 657 Prefix3). 659 Multiple vehicles under the coverage of an RSU share a prefix such 660 that mobile nodes share a prefix of a Wi-Fi access point in a 661 wireless LAN. This is a natural characteristic in infrastructure- 662 based wireless networks. For example, in Figure 1, two vehicles 663 (i.e., Vehicle2, and Vehicle5) can use Prefix 1 to configure their 664 IPv6 global addresses for V2I communication. Alternatively, mobile 665 nodes can employ an OMNI interface and use their own IPv6 Unique 666 Local Addresses (ULAs) [RFC4193] over the wireless network without 667 requiring the messaging of IPv6 Stateless Address Autoconfiguration 668 (SLAAC) [RFC4862], which uses an on-link prefix provided by the 669 (visited) wireless LAN; this technique is known as "Bring-Your-Own- 670 Addresses". 672 A single subnet prefix announced by an RSU can span multiple vehicles 673 in VANET. For example, in Figure 1, for Prefix 1, three vehicles 674 (i.e., Vehicle1, Vehicle2, and Vehicle5) can construct a connected 675 VANET. Also, for Prefix 2, two vehicles (i.e., Vehicle3 and 676 Vehicle6) can construct another connected VANET, and for Prefix 3, 677 two vehicles (i.e., Vehicle4 and Vehicle7) can construct another 678 connected VANET. Alternatively, each vehicle could employ an OMNI 679 interface with their own ULAs such that no topologically-oriented 680 subnet prefixes need be announced by the RSU. 682 In wireless subnets in vehicular networks (e.g., Subnet1 and Subnet2 683 in Figure 1), vehicles can construct a connected VANET (with an 684 arbitrary graph topology) and can communicate with each other via V2V 685 communication. Vehicle1 can communicate with Vehicle2 via V2V 686 communication, and Vehicle2 can communicate with Vehicle3 via V2V 687 communication because they are within the wireless communication 688 range of each other. On the other hand, Vehicle3 can communicate 689 with Vehicle4 via the vehicular infrastructure (i.e., IP-RSU2 and IP- 690 RSU3) by employing V2I (i.e., V2I2V) communication because they are 691 not within the wireless communication range of each other. 693 For IPv6 packets transported over IEEE 802.11-OCB, [RFC8691] 694 specifies several details, including Maximum Transmission Unit (MTU), 695 frame format, link-local address, address mapping for unicast and 696 multicast, stateless autoconfiguration, and subnet structure. An 697 Ethernet Adaptation (EA) layer is in charge of transforming some 698 parameters between the IEEE 802.11 MAC layer and the IPv6 network 699 layer, which is located between the IEEE 802.11-OCB's logical link 700 control layer and the IPv6 network layer. This IPv6 over 802.11-OCB 701 can be used for both V2V and V2I in IPv6-based vehicular networks. 703 An IPv6 mobility solution is needed for the guarantee of 704 communication continuity in vehicular networks so that a vehicle's 705 TCP session can be continued, or UDP packets can be delivered to a 706 vehicle as a destination without loss while it moves from an IP-RSU's 707 wireless coverage to another IP-RSU's wireless coverage. In 708 Figure 1, assuming that Vehicle2 has a TCP session (or a UDP session) 709 with a corresponding node in the vehicular cloud, Vehicle2 can move 710 from IP-RSU1's wireless coverage to IP-RSU2's wireless coverage. In 711 this case, a handover for Vehicle2 needs to be performed by either a 712 host-based mobility management scheme (e.g., MIPv6 [RFC6275]) or a 713 network-based mobility management scheme (e.g., PMIPv6 [RFC5213] and 714 AERO [RFC6706BIS]). 716 In the host-based mobility scheme (e.g., MIPv6), an IP-RSU plays a 717 role of a home agent. On the other hand, in the network-based 718 mobility scheme (e.g., PMIPv6, an MA plays a role of a mobility 719 management controller such as a Local Mobility Anchor (LMA) in 720 PMIPv6, which also serves vehicles as a home agent, and an IP-RSU 721 plays a role of an access router such as a Mobile Access Gateway 722 (MAG) in PMIPv6 [RFC5213]. The host-based mobility scheme needs 723 client functionality in IPv6 stack of a vehicle as a mobile node for 724 mobility signaling message exchange between the vehicle and home 725 agent. On the other hand, the network-based mobility scheme does not 726 need such a client functionality for a vehicle because the network 727 infrastructure node (e.g., MAG in PMIPv6) as a proxy mobility agent 728 handles the mobility signaling message exchange with the home agent 729 (e.g., LMA in PMIPv6) for the sake of the vehicle. 731 There are a scalability issue and a route optimization issue in the 732 network-based mobility scheme (e.g., PMIPv6) when an MA covers a 733 large vehicular network governing many IP-RSUs. In this case, a 734 distributed mobility scheme (e.g., DMM [RFC7429]) can mitigate the 735 scalability issue by distributing multiple MAs in the vehicular 736 network such that they are positioned closer to vehicles for route 737 optimization and bottleneck mitigation in a central MA in the 738 network-based mobility scheme. All these mobility approaches (i.e., 739 a host-based mobility scheme, network-based mobility scheme, and 740 distributed mobility scheme) and a hybrid approach of a combination 741 of them need to provide an efficient mobility service to vehicles 742 moving fast and moving along with the relatively predictable 743 trajectories along the roadways. 745 In vehicular networks, the control plane can be separated from the 746 data plane for efficient mobility management and data forwarding by 747 using the concept of Software-Defined Networking (SDN) 748 [RFC7149][DMM-FPC]. Note that Forwarding Policy Configuration (FPC) 749 in [DMM-FPC], which is a flexible mobility management system, can 750 manage the separation of data-plane and control-plane in DMM. In 751 SDN, the control plane and data plane are separated for the efficient 752 management of forwarding elements (e.g., switches and routers) where 753 an SDN controller configures the forwarding elements in a centralized 754 way and they perform packet forwarding according to their forwarding 755 tables that are configured by the SDN controller. An MA as an SDN 756 controller needs to efficiently configure and monitor its IP-RSUs and 757 vehicles for mobility management, location management, and security 758 services. 760 The mobility information of a GPS receiver mounted in its vehicle 761 (e.g., position, speed, and direction) can be used to accommodate 762 mobility-aware proactive handover schemes, which can perform the 763 handover of a vehicle according to its mobility and the wireless 764 signal strength of a vehicle and an IP-RSU in a proactive way. 766 Vehicles can use the TCC as their Home Network having a home agent 767 for mobility management as in MIPv6 [RFC6275] and PMIPv6 [RFC5213], 768 so the TCC (or an MA inside the TCC) maintains the mobility 769 information of vehicles for location management. IP tunneling over 770 the wireless link should be avoided for performance efficiency. 771 Also, in vehicular networks, asymmetric links sometimes exist and 772 must be considered for wireless communications such as V2V and V2I. 774 4.2. V2I-based Internetworking 776 This section discusses the internetworking between a vehicle's 777 internal network (i.e., moving network) and an EN's internal network 778 (i.e., fixed network) via V2I communication. The internal network of 779 a vehicle is nowadays constructed with Ethernet by many automotive 780 vendors [In-Car-Network]. Note that an EN can accommodate multiple 781 routers (or switches) and servers (e.g., ECDs, navigation server, and 782 DNS server) in its internal network. 784 A vehicle's internal network often uses Ethernet to interconnect 785 Electronic Control Units (ECUs) in the vehicle. The internal network 786 can support Wi-Fi and Bluetooth to accommodate a driver's and 787 passenger's mobile devices (e.g., smartphone or tablet). The network 788 topology and subnetting depend on each vendor's network configuration 789 for a vehicle and an EN. It is reasonable to consider the 790 interaction between the internal network and an external network 791 within another vehicle or an EN. 793 +-----------------+ 794 (*)<........>(*) +----->| Vehicular Cloud | 795 (2001:DB8:1:1::/64) | | | +-----------------+ 796 +------------------------------+ +---------------------------------+ 797 | v | | v v | 798 | +-------+ +-------+ | | +-------+ +-------+ | 799 | | Host1 | |IP-OBU1| | | |IP-RSU1| | Host3 | | 800 | +-------+ +-------+ | | +-------+ +-------+ | 801 | ^ ^ | | ^ ^ | 802 | | | | | | | | 803 | v v | | v v | 804 | ---------------------------- | | ------------------------------- | 805 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:20:1::/64 | 806 | | | | | | 807 | v | | v | 808 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 809 | | Host2 | |Router1| | | |Router2| |Server1|...|ServerN| | 810 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 811 | ^ ^ | | ^ ^ ^ | 812 | | | | | | | | | 813 | v v | | v v v | 814 | ---------------------------- | | ------------------------------- | 815 | 2001:DB8:10:2::/64 | | 2001:DB8:20:2::/64 | 816 +------------------------------+ +---------------------------------+ 817 Vehicle1 (Moving Network1) EN1 (Fixed Network1) 819 <----> Wired Link <....> Wireless Link (*) Antenna 821 Figure 3: Internetworking between Vehicle and Edge Network 823 As shown in Figure 3, as internal networks, a vehicle's moving 824 network and an EN's fixed network are self-contained networks having 825 multiple subnets and having an edge router (e.g., IP-OBU and IP-RSU) 826 for the communication with another vehicle or another EN. The 827 internetworking between two internal networks via V2I communication 828 requires the exchange of the network parameters and the network 829 prefixes of the internal networks. For the efficiency, the network 830 prefixes of the internal networks (as a moving network) in a vehicle 831 need to be delegated and configured automatically. Note that a 832 moving network's network prefix can be called a Mobile Network Prefix 833 (MNP) [OMNI]. 835 Figure 3 also shows the internetworking between the vehicle's moving 836 network and the EN's fixed network. There exists an internal network 837 (Moving Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and 838 Host2), and two routers (IP-OBU1 and Router1). There exists another 839 internal network (Fixed Network1) inside EN1. EN1 has one host 840 (Host3), two routers (IP-RSU1 and Router2), and the collection of 841 servers (Server1 to ServerN) for various services in the road 842 networks, such as the emergency notification and navigation. 843 Vehicle1's IP-OBU1 (as a mobile router) and EN1's IP-RSU1 (as a fixed 844 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 845 V2I networking. Thus, a host (Host1) in Vehicle1 can communicate 846 with a server (Server1) in EN1 for a vehicular service through 847 Vehicle1's moving network, a wireless link between IP-OBU1 and IP- 848 RSU1, and EN1's fixed network. 850 For the IPv6 communication between an IP-OBU and an IP-RSU or between 851 two neighboring IP-OBUs, they need to know the network parameters, 852 which include MAC layer and IPv6 layer information. The MAC layer 853 information includes wireless link layer parameters, transmission 854 power level, and the MAC address of an external network interface for 855 the internetworking with another IP-OBU or IP-RSU. The IPv6 layer 856 information includes the IPv6 address and network prefix of an 857 external network interface for the internetworking with another IP- 858 OBU or IP-RSU. 860 Through the mutual knowledge of the network parameters of internal 861 networks, packets can be transmitted between the vehicle's moving 862 network and the EN's fixed network. Thus, V2I requires an efficient 863 protocol for the mutual knowledge of network parameters. 865 As shown in Figure 3, the addresses used for IPv6 transmissions over 866 the wireless link interfaces for IP-OBU and IP-RSU can be either 867 global IPv6 addresses, or IPv6 ULAs as long as IPv6 packets can be 868 routed within vehicular networks [OMNI]. When global IPv6 addresses 869 are used, wireless interface configuration and control overhead for 870 Duplicate Address Detection (DAD) [RFC4862] and Multicast Listener 871 Discovery (MLD) [RFC2710][RFC3810] should be minimized to support V2I 872 and V2X communications for vehicles moving fast along roadways; when 873 ULAs and the OMNI interface are used, no DAD nor MLD messaging is 874 needed. 876 4.3. V2V-based Internetworking 878 This section discusses the internetworking between the moving 879 networks of two neighboring vehicles via V2V communication. 881 (*)<..........>(*) 882 (2001:DB8:1:1::/64) | | 883 +------------------------------+ +------------------------------+ 884 | v | | v | 885 | +-------+ +-------+ | | +-------+ +-------+ | 886 | | Host1 | |IP-OBU1| | | |IP-OBU2| | Host3 | | 887 | +-------+ +-------+ | | +-------+ +-------+ | 888 | ^ ^ | | ^ ^ | 889 | | | | | | | | 890 | v v | | v v | 891 | ---------------------------- | | ---------------------------- | 892 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:30:1::/64 | 893 | | | | | | 894 | v | | v | 895 | +-------+ +-------+ | | +-------+ +-------+ | 896 | | Host2 | |Router1| | | |Router2| | Host4 | | 897 | +-------+ +-------+ | | +-------+ +-------+ | 898 | ^ ^ | | ^ ^ | 899 | | | | | | | | 900 | v v | | v v | 901 | ---------------------------- | | ---------------------------- | 902 | 2001:DB8:10:2::/64 | | 2001:DB8:30:2::/64 | 903 +------------------------------+ +------------------------------+ 904 Vehicle1 (Moving Network1) Vehicle2 (Moving Network2) 906 <----> Wired Link <....> Wireless Link (*) Antenna 908 Figure 4: Internetworking between Two Vehicles 910 Figure 4 shows the internetworking between the moving networks of two 911 neighboring vehicles. There exists an internal network (Moving 912 Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and Host2), 913 and two routers (IP-OBU1 and Router1). There exists another internal 914 network (Moving Network2) inside Vehicle2. Vehicle2 has two hosts 915 (Host3 and Host4), and two routers (IP-OBU2 and Router2). Vehicle1's 916 IP-OBU1 (as a mobile router) and Vehicle2's IP-OBU2 (as a mobile 917 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 918 V2V networking. Alternatively, Vehicle1 and Vehicle2 employ an OMNI 919 interface and use IPv6 ULAs for V2V networking. Thus, a host (Host1) 920 in Vehicle1 can communicate with another host (Host3) in Vehicle2 for 921 a vehicular service through Vehicle1's moving network, a wireless 922 link between IP-OBU1 and IP-OBU2, and Vehicle2's moving network. 924 As a V2V use case in Section 3.1, Figure 5 shows the linear network 925 topology of platooning vehicles for V2V communications where Vehicle3 926 is the leading vehicle with a driver, and Vehicle2 and Vehicle1 are 927 the following vehicles without drivers. 929 (*)<..................>(*)<..................>(*) 930 | | | 931 +-----------+ +-----------+ +-----------+ 932 | | | | | | 933 | +-------+ | | +-------+ | | +-------+ | 934 | |IP-OBU1| | | |IP-OBU2| | | |IP-OBU3| | 935 | +-------+ | | +-------+ | | +-------+ | 936 | ^ | | ^ | | ^ | 937 | | |=====> | | |=====> | | |=====> 938 | v | | v | | v | 939 | +-------+ | | +-------+ | | +-------+ | 940 | | Host1 | | | | Host2 | | | | Host3 | | 941 | +-------+ | | +-------+ | | +-------+ | 942 | | | | | | 943 +-----------+ +-----------+ +-----------+ 944 Vehicle1 Vehicle2 Vehicle3 946 <----> Wired Link <....> Wireless Link ===> Moving Direction 947 (*) Antenna 949 Figure 5: Multihop Internetworking between Two Vehicle Networks 951 As shown in Figure 5, multihop internetworking is feasible among the 952 moving networks of three vehicles in the same VANET. For example, 953 Host1 in Vehicle1 can communicate with Host3 in Vehicle3 via IP-OBU1 954 in Vehicle1, IP-OBU2 in Vehicle2, and IP-OBU3 in Vehicle3 in the 955 linear network, as shown in the figure. 957 5. Problem Statement 959 In order to specify protocols using the architecture mentioned in 960 Section 4.1, IPv6 core protocols have to be adapted to overcome 961 certain challenging aspects of vehicular networking. Since the 962 vehicles are likely to be moving at great speed, protocol exchanges 963 need to be completed in a time relatively short compared to the 964 lifetime of a link between a vehicle and an IP-RSU, or between two 965 vehicles. 967 Note that if two vehicles are moving in the opposite directions in a 968 roadway, the relative speed of this case is two times the relative 969 speed of a vehicle passing through an RSU. The time constraint of a 970 wireless link between two nodes needs to be considered because it may 971 affect the lifetime of a session involving the link. 973 The lifetime of a session varies depending on the session's type such 974 as a web surfing, voice call over IP, and DNS query. Regardless of a 975 session's type, to guide all the IPv6 packets to their destination 976 host, IP mobility should be supported for the session. 978 Thus, the time constraint of a wireless link has a major impact on 979 IPv6 Neighbor Discovery (ND). Mobility Management (MM) is also 980 vulnerable to disconnections that occur before the completion of 981 identity verification and tunnel management. This is especially true 982 given the unreliable nature of wireless communication. This section 983 presents key topics such as neighbor discovery and mobility 984 management. 986 5.1. Neighbor Discovery 988 IPv6 ND [RFC4861][RFC4862] is a core part of the IPv6 protocol suite. 989 IPv6 ND is designed for link types including point-to-point, 990 multicast-capable (e.g., Ethernet) and Non-Broadcast Multiple Access 991 (NBMA). It assumes the efficient and reliable support of multicast 992 and unicast from the link layer for various network operations such 993 as MAC Address Resolution (AR), DAD, MLD and Neighbor Unreachability 994 Detection (NUD). 996 Vehicles move quickly within the communication coverage of any 997 particular vehicle or IP-RSU. Before the vehicles can exchange 998 application messages with each other, they need to be configured with 999 a link-local IPv6 address or a global IPv6 address, and run IPv6 ND. 1001 The requirements for IPv6 ND for vehicular networks are efficient DAD 1002 and NUD operations. An efficient DAD is required to reduce the 1003 overhead of the DAD packets during a vehicle's travel in a road 1004 network, which guaranteeing the uniqueness of a vehicle's global IPv6 1005 address. An efficient NUD is required to reduce the overhead of the 1006 NUD packets during a vehicle's travel in a road network, which 1007 guaranteeing the accurate neighborhood information of a vehicle in 1008 terms of adjacent vehicles and RSUs. 1010 The legacy DAD assumes that a node with an IPv6 address can reach any 1011 other node with the scope of its address at the time it claims its 1012 address, and can hear any future claim for that address by another 1013 party within the scope of its address for the duration of the address 1014 ownership. However, the partitioning and merging of VANETs makes 1015 this assumption frequently invalid in vehicular networks. The 1016 merging and partitioning of VANETs frequently occurs in vehicular 1017 networks. This merging and partitioning should be considered for the 1018 IPv6 ND such as IPv6 Stateless Address Autoconfiguration (SLAAC) 1019 [RFC4862]. Due to the merging of VANETs, two IPv6 addresses may 1020 conflict with each other though they were unique before the merging. 1021 Also, the partitioning of a VANET may make vehicles with the same 1022 prefix be physically unreachable. Also, SLAAC needs to prevent IPv6 1023 address duplication due to the merging of VANETs. According to the 1024 merging and partitioning, a destination vehicle (as an IPv6 host) 1025 needs to be distinguished as either an on-link host or an off-link 1026 host even though the source vehicle uses the same prefix as the 1027 destination vehicle. 1029 To efficiently prevent IPv6 address duplication due to the VANET 1030 partitioning and merging from happening in vehicular networks, the 1031 vehicular networks need to support a vehicular-network-wide DAD by 1032 defining a scope that is compatible with the legacy DAD. In this 1033 case, two vehicles can communicate with each other when there exists 1034 a communication path over VANET or a combination of VANETs and IP- 1035 RSUs, as shown in Figure 1. By using the vehicular-network-wide DAD, 1036 vehicles can assure that their IPv6 addresses are unique in the 1037 vehicular network whenever they are connected to the vehicular 1038 infrastructure or become disconnected from it in the form of VANET. 1040 ND time-related parameters such as router lifetime and Neighbor 1041 Advertisement (NA) interval need to be adjusted for vehicle speed and 1042 vehicle density. For example, the NA interval needs to be 1043 dynamically adjusted according to a vehicle's speed so that the 1044 vehicle can maintain its neighboring vehicles in a stable way, 1045 considering the collision probability with the NA messages sent by 1046 other vehicles. 1048 For IPv6-based safety applications (e.g., context-aware navigation, 1049 adaptive cruise control, and platooning) in vehicular networks, the 1050 delay-bounded data delivery is critical. IPv6 ND needs to work to 1051 support those IPv6-based safety applications efficiently. 1053 Thus, in IPv6-based vehicular networking, IPv6 ND should have minimum 1054 changes for the interoperability with the legacy IPv6 ND used in the 1055 Internet, including the DAD and NUD operations. 1057 5.1.1. Link Model 1059 A prefix model for a vehicular network needs to facilitate the 1060 communication between two vehicles with the same prefix regardless of 1061 the vehicular network topology as long as there exist bidirectional 1062 E2E paths between them in the vehicular network including VANETs and 1063 IP-RSUs. This prefix model allows vehicles with the same prefix to 1064 communicate with each other via a combination of multihop V2V and 1065 multihop V2I with VANETs and IP-RSUs. Note that the OMNI interface 1066 supports an NBMA link model where multihop V2V and V2I communications 1067 use each mobile node's ULAs without need for any DAD or MLD 1068 messaging. 1070 IPv6 protocols work under certain assumptions that do not necessarily 1071 hold for vehicular wireless access link types other than OMNI/NBMA 1072 [VIP-WAVE][RFC5889]; the rest of this section discusses implications 1073 for those link types that do not apply when the OMNI/NBMA link model 1074 is used. For instance, some IPv6 protocols assume symmetry in the 1075 connectivity among neighboring interfaces [RFC6250]. However, radio 1076 interference and different levels of transmission power may cause 1077 asymmetric links to appear in vehicular wireless links. As a result, 1078 a new vehicular link model needs to consider the asymmetry of 1079 dynamically changing vehicular wireless links. 1081 There is a relationship between a link and a prefix, besides the 1082 different scopes that are expected from the link-local and global 1083 types of IPv6 addresses. In an IPv6 link, it is assumed that all 1084 interfaces which are configured with the same subnet prefix and with 1085 on-link bit set can communicate with each other on an IPv6 link. 1086 However, the vehicular link model needs to define the relationship 1087 between a link and a prefix, considering the dynamics of wireless 1088 links and the characteristics of VANET. 1090 A VANET can have a single link between each vehicle pair within 1091 wireless communication range, as shown in Figure 5. When two 1092 vehicles belong to the same VANET, but they are out of wireless 1093 communication range, they cannot communicate directly with each 1094 other. Suppose that a global-scope IPv6 prefix (or an IPv6 ULA 1095 prefix) is assigned to VANETs in vehicular networks. Even though two 1096 vehicles in the same VANET configure their IPv6 addresses with the 1097 same IPv6 prefix, they may not communicate with each other not in one 1098 hop in the same VANET because of the multihop network connectivity 1099 between them. Thus, in this case, the concept of an on-link IPv6 1100 prefix does not hold because two vehicles with the same on-link IPv6 1101 prefix cannot communicate directly with each other. Also, when two 1102 vehicles are located in two different VANETs with the same IPv6 1103 prefix, they cannot communicate with each other. When these two 1104 VANETs converge to one VANET, the two vehicles can communicate with 1105 each other in a multihop fashion, for example, when they are Vehicle1 1106 and Vehicle3, as shown in Figure 5. 1108 From the previous observation, a vehicular link model should consider 1109 the frequent partitioning and merging of VANETs due to vehicle 1110 mobility. Therefore, the vehicular link model needs to use an on- 1111 link prefix and off-link prefix according to the network topology of 1112 vehicles such as a one-hop reachable network and a multihop reachable 1113 network (or partitioned networks). If the vehicles with the same 1114 prefix are reachable from each other in one hop, the prefix should be 1115 on-link. On the other hand, if some of the vehicles with the same 1116 prefix are not reachable from each other in one hop due to either the 1117 multihop topology in the VANET or multiple partitions, the prefix 1118 should be off-link. 1120 The vehicular link model needs to support multihop routing in a 1121 connected VANET where the vehicles with the same global-scope IPv6 1122 prefix (or the same IPv6 ULA prefix) are connected in one hop or 1123 multiple hops. It also needs to support the multihop routing in 1124 multiple connected VANETs through infrastructure nodes (e.g., IP-RSU) 1125 where they are connected to the infrastructure. For example, in 1126 Figure 1, suppose that Vehicle1, Vehicle2, and Vehicle3 are 1127 configured with their IPv6 addresses based on the same global-scope 1128 IPv6 prefix. Vehicle1 and Vehicle3 can also communicate with each 1129 other via either multihop V2V or multihop V2I2V. When Vehicle1 and 1130 Vehicle3 are connected in a VANET, it will be more efficient for them 1131 to communicate with each other directly via VANET rather than 1132 indirectly via IP-RSUs. On the other hand, when Vehicle1 and 1133 Vehicle3 are far away from direct communication range in separate 1134 VANETs and under two different IP-RSUs, they can communicate with 1135 each other through the relay of IP-RSUs via V2I2V. Thus, two 1136 separate VANETs can merge into one network via IP-RSU(s). Also, 1137 newly arriving vehicles can merge two separate VANETs into one VANET 1138 if they can play the role of a relay node for those VANETs. 1140 Thus, in IPv6-based vehicular networking, the vehicular link model 1141 should have minimum changes for interoperability with standard IPv6 1142 links in an efficient fashion to support IPv6 DAD, MLD and NUD 1143 operations. When the OMNI NBMA link model is used, there are no link 1144 model changes nor DAD/MLD messaging required. 1146 5.1.2. MAC Address Pseudonym 1148 For the protection of drivers' privacy, a pseudonym of a MAC address 1149 of a vehicle's network interface should be used, so that the MAC 1150 address can be changed periodically. However, although such a 1151 pseudonym of a MAC address can protect to some extent the privacy of 1152 a vehicle, it may not be able to resist attacks on vehicle 1153 identification by other fingerprint information, for example, the 1154 scrambler seed embedded in IEEE 802.11-OCB frames [Scrambler-Attack]. 1155 The pseudonym of a MAC address affects an IPv6 address based on the 1156 MAC address, and a transport-layer (e.g., TCP and SCTP) session with 1157 an IPv6 address pair. However, the pseudonym handling is not 1158 implemented and tested yet for applications on IP-based vehicular 1159 networking. 1161 In the ETSI standards, for the sake of security and privacy, an ITS 1162 station (e.g., vehicle) can use pseudonyms for its network interface 1163 identities (e.g., MAC address) and the corresponding IPv6 addresses 1164 [Identity-Management]. Whenever the network interface identifier 1165 changes, the IPv6 address based on the network interface identifier 1166 needs to be updated, and the uniqueness of the address needs to be 1167 checked through the DAD procedure. For vehicular networks with high 1168 mobility and density, this DAD needs to be performed efficiently with 1169 minimum overhead so that the vehicles can exchange application 1170 messages (e.g., collision avoidance and accident notification) with 1171 each other with a short interval (e.g., 0.5 second) 1172 [NHTSA-ACAS-Report]. 1174 5.1.3. Routing 1176 For multihop V2V communications in either a VANET or VANETs via IP- 1177 RSUs, a vehicular Mobile Ad Hoc Networks (MANET) routing protocol may 1178 be required to support both unicast and multicast in the links of the 1179 subnet with the same IPv6 prefix. However, it will be costly to run 1180 both vehicular ND and a vehicular ad hoc routing protocol in terms of 1181 control traffic overhead [ID-Multicast-Problems]. 1183 A routing protocol for a VANET may cause redundant wireless frames in 1184 the air to check the neighborhood of each vehicle and compute the 1185 routing information in a VANET with a dynamic network topology 1186 because the IPv6 ND is used to check the neighborhood of each 1187 vehicle. Thus, the vehicular routing needs to take advantage of the 1188 IPv6 ND to minimize its control overhead. 1190 5.2. Mobility Management 1192 The seamless connectivity and timely data exchange between two end 1193 points requires efficient mobility management including location 1194 management and handover. Most vehicles are equipped with a GPS 1195 receiver as part of a dedicated navigation system or a corresponding 1196 smartphone App. Note that the GPS receiver may not provide vehicles 1197 with accurate location information in adverse environments such as a 1198 building area or a tunnel. The location precision can be improved 1199 with assistance of the IP-RSUs or a cellular system with a GPS 1200 receiver for location information. 1202 With a GPS navigator, efficient mobility management can be performed 1203 with the help of vehicles periodically reporting their current 1204 position and trajectory (i.e., navigation path) to the vehicular 1205 infrastructure (having IP-RSUs and an MA in TCC). This vehicular 1206 infrastructure can predict the future positions of the vehicles from 1207 their mobility information (i.e., the current position, speed, 1208 direction, and trajectory) for efficient mobility management (e.g., 1209 proactive handover). For a better proactive handover, link-layer 1210 parameters, such as the signal strength of a link-layer frame (e.g., 1211 Received Channel Power Indicator (RCPI) [VIP-WAVE]), can be used to 1212 determine the moment of a handover between IP-RSUs along with 1213 mobility information. 1215 By predicting a vehicle's mobility, the vehicular infrastructure 1216 needs to better support IP-RSUs to perform efficient SLAAC, data 1217 forwarding, horizontal handover (i.e., handover in wireless links 1218 using a homogeneous radio technology), and vertical handover (i.e., 1219 handover in wireless links using heterogeneous radio technologies) in 1220 advance along with the movement of the vehicle. 1222 For example, as shown in Figure 1, when a vehicle (e.g., Vehicle2) is 1223 moving from the coverage of an IP-RSU (e.g., IP-RSU1) into the 1224 coverage of another IP-RSU (e.g., IP-RSU2) belonging to a different 1225 subnet, the IP-RSUs can proactively support the IPv6 mobility of the 1226 vehicle, while performing the SLAAC, data forwarding, and handover 1227 for the sake of the vehicle. 1229 For a mobility management scheme in a shared link, where the wireless 1230 subnets of multiple IP-RSUs share the same prefix, an efficient 1231 vehicular-network-wide DAD is required. If DHCPv6 is used to assign 1232 a unique IPv6 address to each vehicle in this shared link, the DAD is 1233 not required. On the other hand, for a mobility management scheme 1234 with a unique prefix per mobile node (e.g., PMIPv6 [RFC5213] and OMNI 1235 [OMNI]), DAD is not required because the IPv6 address of a vehicle's 1236 external wireless interface is guaranteed to be unique. There is a 1237 tradeoff between the prefix usage efficiency and DAD overhead. Thus, 1238 the IPv6 address autoconfiguration for vehicular networks needs to 1239 consider this tradeoff to support efficient mobility management. 1241 Therefore, for the proactive and seamless IPv6 mobility of vehicles, 1242 the vehicular infrastructure (including IP-RSUs and MA) needs to 1243 efficiently perform the mobility management of the vehicles with 1244 their mobility information and link-layer information. Also, in 1245 IPv6-based vehicular networking, IPv6 mobility management should have 1246 minimum changes for the interoperability with the legacy IPv6 1247 mobility management schemes such as PMIPv6, DMM, LISP, and AERO. 1249 6. Security Considerations 1251 This section discusses security and privacy for IPv6-based vehicular 1252 networking. Security and privacy are key components of IPv6-based 1253 vehicular networking along with neighbor discovery and mobility 1254 management. 1256 Security and privacy are paramount in V2I, V2V, and V2X networking. 1257 Vehicles and infrastructure must be authenticated in order to 1258 participate in vehicular networking. Also, in-vehicle devices (e.g., 1259 ECU) and a driver/passenger's mobile devices (e.g., smartphone and 1260 tablet PC) in a vehicle need to communicate with other in-vehicle 1261 devices and another driver/passenger's mobile devices in another 1262 vehicle, or other servers behind an IP-RSU in a secure way. Even 1263 though a vehicle is perfectly authenticated and legitimate, it may be 1264 hacked for running malicious applications to track and collect its 1265 and other vehicles' information. In this case, an attack mitigation 1266 process may be required to reduce the aftermath of malicious 1267 behaviors. 1269 Strong security measures shall protect vehicles roaming in road 1270 networks from the attacks of malicious nodes, which are controlled by 1271 hackers. For safe driving applications (e.g., context-aware 1272 navigation, cooperative adaptive cruise control, and platooning), as 1273 explained in Section 3.1, the cooperative action among vehicles is 1274 assumed. Malicious nodes may disseminate wrong driving information 1275 (e.g., location, speed, and direction) for disturbing safe driving. 1276 For example, a Sybil attack, which tries to confuse a vehicle with 1277 multiple false identities, may disturb a vehicle from taking a safe 1278 maneuver. 1280 Even though vehicles can be authenticated with valid certificates by 1281 an authentication server in the vehicular cloud, the authenticated 1282 vehicles may harm other vehicles, so their communication activities 1283 need to be logged in either a central way through a logging server 1284 (e.g., TCC) in the vehicular cloud or a distributed way (e.g., 1285 blockchain [Bitcoin]) along with other vehicles or infrastructure. 1286 For the non-repudiation of the harmful activities of malicious nodes, 1287 a blockchain technology can be used [Bitcoin]. Each message from a 1288 vehicle can be treated as a transaction and the neighboring vehicles 1289 can play the role of peers in a consensus method of a blockchain 1290 [Bitcoin][Vehicular-BlockChain]. For a blockchain's efficient 1291 consensus in vehicular networks having fast moving vehicles, a new 1292 consensus algorithm needs to be developed or an existing consensus 1293 algorithm needs to be enhanced. 1295 To identify malicious vehicles among vehicles, an authentication 1296 method is required. A Vehicle Identification Number (VIN) and a user 1297 certificate (e.g., X.509 certificate [RFC5280]) along with an in- 1298 vehicle device's identifier generation can be used to efficiently 1299 authenticate a vehicle or its driver (having a user certificate) 1300 through a road infrastructure node (e.g., IP-RSU) connected to an 1301 authentication server in the vehicular cloud. This authentication 1302 can be used to identify the vehicle that will communicate with an 1303 infrastructure node or another vehicle. In the case where a vehicle 1304 has an internal network (called Moving Network) and elements in the 1305 network (e.g., in-vehicle devices and a user's mobile devices), as 1306 shown in Figure 3, the elements in the network need to be 1307 authenticated individually for safe authentication. Also, Transport 1308 Layer Security (TLS) certificates [RFC8446][RFC5280] can be used for 1309 an element's authentication to allow secure E2E vehicular 1310 communications between an element in a vehicle and another element in 1311 a server in a vehicular cloud, or between an element in a vehicle and 1312 another element in another vehicle. 1314 For secure V2I communication, a secure channel (e.g., IPsec) between 1315 a mobile router (i.e., IP-OBU) in a vehicle and a fixed router (i.e., 1316 IP-RSU) in an EN needs to be established, as shown in Figure 3 1317 [RFC4301][RFC4302][RFC4303][RFC4308][RFC7296]. Also, for secure V2V 1318 communication, a secure channel (e.g., IPsec) between a mobile router 1319 (i.e., IP-OBU) in a vehicle and a mobile router (i.e., IP-OBU) in 1320 another vehicle needs to be established, as shown in Figure 4. For 1321 secure communication, an element in a vehicle (e.g., an in-vehicle 1322 device and a driver/passenger's mobile device) needs to establish a 1323 secure connection (e.g., TLS) with another element in another vehicle 1324 or another element in a vehicular cloud (e.g., a server). Even 1325 though IEEE 1609.2 [WAVE-1609.2] specifies security services for 1326 applications and management messages. This WAVE specification is 1327 optional, so if WAVE does not support the security of a WAVE frame, 1328 either the network layer or the transport layer needs to support 1329 security services for the WAVE frames. 1331 For the setup of a secure channel over IPsec or TLS, the multihop V2I 1332 communications over DSRC is required in a highway for the 1333 authentication by involving multiple intermediate vehicles as relay 1334 nodes toward an IP-RSU connected to an authentication server in the 1335 vehicular cloud. The V2I communications over 5G V2X (or LTE V2X) is 1336 required to allow a vehicle to communicate directly with a gNodeB (or 1337 eNodeB) connected to an authentication server in the vehicular cloud. 1339 To prevent an adversary from tracking a vehicle with its MAC address 1340 or IPv6 address, especially for a long-living transport-layer session 1341 (e.g., voice call over IP and video streaming service), a MAC address 1342 pseudonym needs to be provided to each vehicle; that is, each vehicle 1343 periodically updates its MAC address and its IPv6 address needs to be 1344 updated accordingly by the MAC address change [RFC4086][RFC4941]. 1345 Such an update of the MAC and IPv6 addresses should not interrupt the 1346 E2E communications between two vehicles (or between a vehicle and an 1347 IP-RSU) for a long-living transport-layer session. However, if this 1348 pseudonym is performed without strong E2E confidentiality (using 1349 either IPsec or TLS), there will be no privacy benefit from changing 1350 MAC and IPv6 addresses, because an adversary can observe the change 1351 of the MAC and IPv6 addresses and track the vehicle with those 1352 addresses. Thus, the MAC address pseudonym and the IPv6 address 1353 update should be performed with strong E2E confidentiality. 1355 For the IPv6 ND, the DAD is required to ensure the uniqueness of the 1356 IPv6 address of a vehicle's wireless interface. This DAD can be used 1357 as a flooding attack that uses the DAD-related ND packets 1358 disseminated over the VANET or vehicular networks. Thus, the 1359 vehicles and IP-RSUs need to filter out suspicious ND traffic in 1360 advance. 1362 For mobility management, a malicious vehicle can construct multiple 1363 virtual bogus vehicles, and register them with IP-RSUs and MA. This 1364 registration makes the IP-RSUs and MA waste their resources. The IP- 1365 RSUs and MA need to determine whether a vehicle is genuine or bogus 1366 in mobility management. Also, the confidentiality of control packets 1367 and data packets among IP-RSUs and MA, the E2E paths (e.g., tunnels) 1368 need to be protected by secure communication channels. In addition, 1369 to prevent bogus IP-RSUs and MA from interfering with the IPv6 1370 mobility of vehicles, mutual authentication among them needs to be 1371 performed by certificates (e.g., TLS certificate). 1373 7. Informative References 1375 [Automotive-Sensing] 1376 Choi, J., Va, V., Gonzalez-Prelcic, N., Daniels, R., R. 1377 Bhat, C., and R. W. Heath, "Millimeter-Wave Vehicular 1378 Communication to Support Massive Automotive Sensing", 1379 IEEE Communications Magazine, December 2016. 1381 [Bitcoin] Nakamoto, S., "Bitcoin: A Peer-to-Peer Electronic Cash 1382 System", URL: https://bitcoin.org/bitcoin.pdf, May 2009. 1384 [CA-Cruise-Control] 1385 California Partners for Advanced Transportation Technology 1386 (PATH), "Cooperative Adaptive Cruise Control", [Online] 1387 Available: 1388 http://www.path.berkeley.edu/research/automated-and- 1389 connected-vehicles/cooperative-adaptive-cruise-control, 1390 2017. 1392 [CASD] Shen, Y., Jeong, J., Oh, T., and S. Son, "CASD: A 1393 Framework of Context-Awareness Safety Driving in Vehicular 1394 Networks", International Workshop on Device Centric Cloud 1395 (DC2), March 2016. 1397 [CBDN] Kim, J., Kim, S., Jeong, J., Kim, H., Park, J., and T. 1398 Kim, "CBDN: Cloud-Based Drone Navigation for Efficient 1399 Battery Charging in Drone Networks", IEEE Transactions on 1400 Intelligent Transportation Systems, November 2019. 1402 [DMM-FPC] Matsushima, S., Bertz, L., Liebsch, M., Gundavelli, S., 1403 Moses, D., and C. Perkins, "Protocol for Forwarding Policy 1404 Configuration (FPC) in DMM", draft-ietf-dmm-fpc-cpdp-13 1405 (work in progress), March 2020. 1407 [DSRC] ASTM International, "Standard Specification for 1408 Telecommunications and Information Exchange Between 1409 Roadside and Vehicle Systems - 5 GHz Band Dedicated Short 1410 Range Communications (DSRC) Medium Access Control (MAC) 1411 and Physical Layer (PHY) Specifications", 1412 ASTM E2213-03(2010), October 2010. 1414 [EU-2008-671-EC] 1415 European Union, "Commission Decision of 5 August 2008 on 1416 the Harmonised Use of Radio Spectrum in the 5875 - 5905 1417 MHz Frequency Band for Safety-related Applications of 1418 Intelligent Transport Systems (ITS)", EU 2008/671/EC, 1419 August 2008. 1421 [FirstNet] 1422 U.S. National Telecommunications and Information 1423 Administration (NTIA), "First Responder Network Authority 1424 (FirstNet)", [Online] 1425 Available: https://www.firstnet.gov/, 2012. 1427 [FirstNet-Report] 1428 First Responder Network Authority, "FY 2017: ANNUAL REPORT 1429 TO CONGRESS, Advancing Public Safety Broadband 1430 Communications", FirstNet FY 2017, December 2017. 1432 [Fuel-Efficient] 1433 van de Hoef, S., H. Johansson, K., and D. V. Dimarogonas, 1434 "Fuel-Efficient En Route Formation of Truck Platoons", 1435 IEEE Transactions on Intelligent Transportation Systems, 1436 January 2018. 1438 [ID-Multicast-Problems] 1439 Perkins, C., McBride, M., Stanley, D., Kumari, W., and JC. 1440 Zuniga, "Multicast Considerations over IEEE 802 Wireless 1441 Media", draft-ietf-mboned-ieee802-mcast-problems-11 (work 1442 in progress), December 2019. 1444 [Identity-Management] 1445 Wetterwald, M., Hrizi, F., and P. Cataldi, "Cross-layer 1446 Identities Management in ITS Stations", The 10th 1447 International Conference on ITS Telecommunications, 1448 November 2010. 1450 [IEEE-802.11-OCB] 1451 "Part 11: Wireless LAN Medium Access Control (MAC) and 1452 Physical Layer (PHY) Specifications", IEEE Std 1453 802.11-2016, December 2016. 1455 [IEEE-802.11p] 1456 "Part 11: Wireless LAN Medium Access Control (MAC) and 1457 Physical Layer (PHY) Specifications - Amendment 6: 1458 Wireless Access in Vehicular Environments", IEEE Std 1459 802.11p-2010, June 2010. 1461 [In-Car-Network] 1462 Lim, H., Volker, L., and D. Herrscher, "Challenges in a 1463 Future IP/Ethernet-based In-Car Network for Real-Time 1464 Applications", ACM/EDAC/IEEE Design Automation Conference 1465 (DAC), June 2011. 1467 [ISO-ITS-IPv6] 1468 ISO/TC 204, "Intelligent Transport Systems - 1469 Communications Access for Land Mobiles (CALM) - IPv6 1470 Networking", ISO 21210:2012, June 2012. 1472 [ISO-ITS-IPv6-AMD1] 1473 ISO/TC 204, "Intelligent Transport Systems - 1474 Communications Access for Land Mobiles (CALM) - IPv6 1475 Networking - Amendment 1", ISO 21210:2012/AMD 1:2017, 1476 September 2017. 1478 [NHTSA-ACAS-Report] 1479 National Highway Traffic Safety Administration (NHTSA), 1480 "Final Report of Automotive Collision Avoidance Systems 1481 (ACAS) Program", DOT HS 809 080, August 2000. 1483 [OMNI] Templin, F. and A. Whyman, "Transmission of IPv6 Packets 1484 over Overlay Multilink Network (OMNI) Interfaces", draft- 1485 templin-6man-omni-interface-24 (work in progress), June 1486 2020. 1488 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1489 Listener Discovery (MLD) for IPv6", RFC 2710, October 1490 1999. 1492 [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- 1493 Demand Distance Vector (AODV) Routing", RFC 3561, July 1494 2003. 1496 [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", 1497 RFC 3753, June 2004. 1499 [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery 1500 Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. 1502 [RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix 1503 Reserved for Documentation", RFC 3849, July 2004. 1505 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1506 "Randomness Requirements for Security", RFC 4086, June 1507 2005. 1509 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 1510 Addresses", RFC 4193, October 2005. 1512 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1513 Internet Protocol", RFC 4301, December 2005. 1515 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, December 1516 2005. 1518 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1519 RFC 4303, December 2005. 1521 [RFC4308] Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308, 1522 December 2005. 1524 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1525 "Neighbor Discovery for IP Version 6 (IPv6)", RFC 4861, 1526 September 2007. 1528 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1529 Address Autoconfiguration", RFC 4862, September 2007. 1531 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1532 Extensions for Stateless Address Autoconfiguration in 1533 IPv6", RFC 4941, September 2007. 1535 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1536 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1537 RFC 5213, August 2008. 1539 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1540 Housley, R., and W. Polk, "Internet X.509 Public Key 1541 Infrastructure Certificate and Certificate Revocation List 1542 (CRL) Profile", RFC 5280, May 2008. 1544 [RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And 1545 Provisioning of Wireless Access Points (CAPWAP) Protocol 1546 Specification", RFC 5415, March 2009. 1548 [RFC5889] Baccelli, E. and M. Townsley, "IP Addressing Model in Ad 1549 Hoc Networks", RFC 5889, September 2010. 1551 [RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250, May 1552 2011. 1554 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1555 Support in IPv6", RFC 6275, July 2011. 1557 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 1558 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 1559 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 1560 Lossy Networks", RFC 6550, March 2012. 1562 [RFC6706BIS] 1563 Templin, F., "Asymmetric Extended Route Optimization 1564 (AERO)", draft-templin-intarea-6706bis-58 (work in 1565 progress), June 2020. 1567 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 1568 "Neighbor Discovery Optimization for IPv6 over Low-Power 1569 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 1570 November 2012. 1572 [RFC6830BIS] 1573 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 1574 Cabellos, "The Locator/ID Separation Protocol (LISP)", 1575 draft-ietf-lisp-rfc6830bis-32 (work in progress), March 1576 2020. 1578 [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined 1579 Networking: A Perspective from within a Service Provider 1580 Environment", RFC 7149, March 2014. 1582 [RFC7181] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg, 1583 "The Optimized Link State Routing Protocol Version 2", 1584 RFC 7181, April 2014. 1586 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1587 Kivinen, "Internet Key Exchange Protocol Version 2 1588 (IKEv2)", RFC 7296, October 2014. 1590 [RFC7333] Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen, 1591 "Requirements for Distributed Mobility Management", 1592 RFC 7333, August 2014. 1594 [RFC7429] Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ. 1595 Bernardos, "Distributed Mobility Management: Current 1596 Practices and Gap Analysis", RFC 7429, January 2015. 1598 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1599 (IPv6) Specification", RFC 8200, July 2017. 1601 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 1602 Version 1.3", RFC 8446, August 2018. 1604 [RFC8691] Benamar, N., Haerri, J., Lee, J., and T. Ernst, "Basic 1605 Support for IPv6 Networks Operating Outside the Context of 1606 a Basic Service Set over IEEE Std 802.11", RFC 8691, 1607 December 2019. 1609 [SAINT] Jeong, J., Jeong, H., Lee, E., Oh, T., and D. Du, "SAINT: 1610 Self-Adaptive Interactive Navigation Tool for Cloud-Based 1611 Vehicular Traffic Optimization", IEEE Transactions on 1612 Vehicular Technology, Vol. 65, No. 6, June 2016. 1614 [SAINTplus] 1615 Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., and D. 1616 Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+ 1617 for Emergency Service Delivery Optimization", 1618 IEEE Transactions on Intelligent Transportation Systems, 1619 June 2017. 1621 [SANA] Hwang, T. and J. Jeong, "SANA: Safety-Aware Navigation 1622 Application for Pedestrian Protection in Vehicular 1623 Networks", Springer Lecture Notes in Computer Science 1624 (LNCS), Vol. 9502, December 2015. 1626 [Scrambler-Attack] 1627 Bloessl, B., Sommer, C., Dressier, F., and D. Eckhoff, 1628 "The Scrambler Attack: A Robust Physical Layer Attack on 1629 Location Privacy in Vehicular Networks", IEEE 2015 1630 International Conference on Computing, Networking and 1631 Communications (ICNC), February 2015. 1633 [SignalGuru] 1634 Koukoumidis, E., Peh, L., and M. Martonosi, "SignalGuru: 1635 Leveraging Mobile Phones for Collaborative Traffic Signal 1636 Schedule Advisory", ACM MobiSys, June 2011. 1638 [TR-22.886-3GPP] 1639 3GPP, "Study on Enhancement of 3GPP Support for 5G V2X 1640 Services", 3GPP TR 22.886/Version 16.2.0, December 2018. 1642 [Truck-Platooning] 1643 California Partners for Advanced Transportation Technology 1644 (PATH), "Automated Truck Platooning", [Online] Available: 1645 http://www.path.berkeley.edu/research/automated-and- 1646 connected-vehicles/truck-platooning, 2017. 1648 [TS-23.285-3GPP] 1649 3GPP, "Architecture Enhancements for V2X Services", 3GPP 1650 TS 23.285/Version 16.2.0, December 2019. 1652 [TS-23.287-3GPP] 1653 3GPP, "Architecture Enhancements for 5G System (5GS) to 1654 Support Vehicle-to-Everything (V2X) Services", 3GPP 1655 TS 23.287/Version 16.2.0, March 2020. 1657 [UAM-ITS] Templin, F., "Urban Air Mobility Implications for 1658 Intelligent Transportation Systems", draft-templin-ipwave- 1659 uam-its-03 (work in progress), July 2020. 1661 [Vehicular-BlockChain] 1662 Dorri, A., Steger, M., Kanhere, S., and R. Jurdak, 1663 "BlockChain: A Distributed Solution to Automotive Security 1664 and Privacy", IEEE Communications Magazine, Vol. 55, No. 1665 12, December 2017. 1667 [VIP-WAVE] 1668 Cespedes, S., Lu, N., and X. Shen, "VIP-WAVE: On the 1669 Feasibility of IP Communications in 802.11p Vehicular 1670 Networks", IEEE Transactions on Intelligent Transportation 1671 Systems, vol. 14, no. 1, March 2013. 1673 [WAVE-1609.0] 1674 IEEE 1609 Working Group, "IEEE Guide for Wireless Access 1675 in Vehicular Environments (WAVE) - Architecture", IEEE Std 1676 1609.0-2013, March 2014. 1678 [WAVE-1609.2] 1679 IEEE 1609 Working Group, "IEEE Standard for Wireless 1680 Access in Vehicular Environments - Security Services for 1681 Applications and Management Messages", IEEE Std 1682 1609.2-2016, March 2016. 1684 [WAVE-1609.3] 1685 IEEE 1609 Working Group, "IEEE Standard for Wireless 1686 Access in Vehicular Environments (WAVE) - Networking 1687 Services", IEEE Std 1609.3-2016, April 2016. 1689 [WAVE-1609.4] 1690 IEEE 1609 Working Group, "IEEE Standard for Wireless 1691 Access in Vehicular Environments (WAVE) - Multi-Channel 1692 Operation", IEEE Std 1609.4-2016, March 2016. 1694 Appendix A. Acknowledgments 1696 This work was supported by Institute of Information & Communications 1697 Technology Planning & Evaluation (IITP) grant funded by the Korea 1698 MSIT (Ministry of Science and ICT) (R-20160222-002755, Cloud based 1699 Security Intelligence Technology Development for the Customized 1700 Security Service Provisioning). 1702 This work was supported in part by the MSIT (Ministry of Science and 1703 ICT), Korea, under the ITRC (Information Technology Research Center) 1704 support program (IITP-2019-2017-0-01633) supervised by the IITP 1705 (Institute for Information & communications Technology Promotion). 1707 This work was supported in part by the French research project 1708 DataTweet (ANR-13-INFR-0008) and in part by the HIGHTS project funded 1709 by the European Commission I (636537-H2020). 1711 Appendix B. Contributors 1713 This document is a group work of IPWAVE working group, greatly 1714 benefiting from inputs and texts by Rex Buddenberg (Naval 1715 Postgraduate School), Thierry Ernst (YoGoKo), Bokor Laszlo (Budapest 1716 University of Technology and Economics), Jose Santa Lozanoi 1717 (Universidad of Murcia), Richard Roy (MIT), Francois Simon (Pilot), 1718 Sri Gundavelli (Cisco), Erik Nordmark, Dirk von Hugo (Deutsche 1719 Telekom), Pascal Thubert (Cisco), Carlos Bernardos (UC3M), Russ 1720 Housley (Vigil Security), Suresh Krishnan (Kaloom), Nancy Cam-Winget 1721 (Cisco), Fred L. Templin (The Boeing Company), Jung-Soo Park (ETRI), 1722 Zeungil (Ben) Kim (Hyundai Motors), Kyoungjae Sun (Soongsil 1723 University), Zhiwei Yan (CNNIC), YongJoon Joe (LSware), and Peter E. 1724 Yee (Akayla). The authors sincerely appreciate their contributions. 1726 The following are co-authors of this document: 1728 Nabil Benamar 1729 Department of Computer Sciences 1730 High School of Technology of Meknes 1731 Moulay Ismail University 1732 Morocco 1734 Phone: +212 6 70 83 22 36 1735 EMail: benamar73@gmail.com 1737 Sandra Cespedes 1738 NIC Chile Research Labs 1739 Universidad de Chile 1740 Av. Blanco Encalada 1975 1741 Santiago 1742 Chile 1744 Phone: +56 2 29784093 1745 EMail: scespede@niclabs.cl 1747 Jerome Haerri 1748 Communication Systems Department 1749 EURECOM 1750 Sophia-Antipolis 1751 France 1753 Phone: +33 4 93 00 81 34 1754 EMail: jerome.haerri@eurecom.fr 1756 Dapeng Liu 1757 Alibaba 1758 Beijing, Beijing 100022 1759 China 1761 Phone: +86 13911788933 1762 EMail: max.ldp@alibaba-inc.com 1764 Tae (Tom) Oh 1765 Department of Information Sciences and Technologies 1766 Rochester Institute of Technology 1767 One Lomb Memorial Drive 1768 Rochester, NY 14623-5603 1769 USA 1771 Phone: +1 585 475 7642 1772 EMail: Tom.Oh@rit.edu 1774 Charles E. Perkins 1775 Futurewei Inc. 1776 2330 Central Expressway 1777 Santa Clara, CA 95050 1778 USA 1780 Phone: +1 408 330 4586 1781 EMail: charliep@computer.org 1782 Alexandre Petrescu 1783 CEA, LIST 1784 CEA Saclay 1785 Gif-sur-Yvette, Ile-de-France 91190 1786 France 1788 Phone: +33169089223 1789 EMail: Alexandre.Petrescu@cea.fr 1791 Yiwen Chris Shen 1792 Department of Computer Science & Engineering 1793 Sungkyunkwan University 1794 2066 Seobu-Ro, Jangan-Gu 1795 Suwon, Gyeonggi-Do 16419 1796 Republic of Korea 1798 Phone: +82 31 299 4106 1799 Fax: +82 31 290 7996 1800 EMail: chrisshen@skku.edu 1801 URI: http://iotlab.skku.edu/people-chris-shen.php 1803 Michelle Wetterwald 1804 FBConsulting 1805 21, Route de Luxembourg 1806 Wasserbillig, Luxembourg L-6633 1807 Luxembourg 1809 EMail: Michelle.Wetterwald@gmail.com 1811 Author's Address 1813 Jaehoon Paul Jeong (editor) 1814 Department of Computer Science and Engineering 1815 Sungkyunkwan University 1816 2066 Seobu-Ro, Jangan-Gu 1817 Suwon, Gyeonggi-Do 16419 1818 Republic of Korea 1820 Phone: +82 31 299 4957 1821 Fax: +82 31 290 7996 1822 EMail: pauljeong@skku.edu 1823 URI: http://iotlab.skku.edu/people-jaehoon-jeong.php