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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 29, 2020 5 Expires: January 30, 2021 7 IPv6 Wireless Access in Vehicular Environments (IPWAVE): Problem 8 Statement and Use Cases 9 draft-ietf-ipwave-vehicular-networking-18 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 30, 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. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 77 8. Informative References . . . . . . . . . . . . . . . . . . . 30 78 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 37 79 Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 37 80 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 39 82 1. Introduction 84 Vehicular networking studies have mainly focused on improving safety 85 and efficiency, and also enabling entertainment in vehicular 86 networks. The Federal Communications Commission (FCC) in the US 87 allocated wireless channels for Dedicated Short-Range Communications 88 (DSRC) [DSRC] in the Intelligent Transportation Systems (ITS) with 89 the frequency band of 5.850 - 5.925 GHz (i.e., 5.9 GHz band). DSRC- 90 based wireless communications can support vehicle-to-vehicle (V2V), 91 vehicle-to-infrastructure (V2I), and vehicle-to-everything (V2X) 92 networking. The European Union (EU) allocated radio spectrum for 93 safety-related and non-safety-related applications of ITS with the 94 frequency band of 5.875 - 5.905 GHz, as part of the Commission 95 Decision 2008/671/EC [EU-2008-671-EC]. 97 For direct inter-vehicular wireless connectivity, IEEE has amended 98 standard 802.11 (commonly known as Wi-Fi) to enable safe driving 99 services based on DSRC for the Wireless Access in Vehicular 100 Environments (WAVE) system. The Physical Layer (L1) and Data Link 101 Layer (L2) issues are addressed in IEEE 802.11p [IEEE-802.11p] for 102 the PHY and MAC of the DSRC, while IEEE 1609.2 [WAVE-1609.2] covers 103 security aspects, IEEE 1609.3 [WAVE-1609.3] defines related services 104 at network and transport layers, and IEEE 1609.4 [WAVE-1609.4] 105 specifies the multi-channel operation. IEEE 802.11p was first a 106 separate amendment, but was later rolled into the base 802.11 107 standard (IEEE 802.11-2012) as IEEE 802.11 Outside the Context of a 108 Basic Service Set (OCB) in 2012 [IEEE-802.11-OCB]. 110 3GPP has standardized Cellular Vehicle-to-Everything (C-V2X) 111 communications to support V2X in LTE mobile networks (called LTE V2X) 112 and V2X in 5G mobile networks (called 5G V2X) [TS-23.285-3GPP] 113 [TR-22.886-3GPP][TS-23.287-3GPP]. With C-V2X, vehicles can directly 114 communicate with each other without relay nodes (e.g., eNodeB in LTE 115 and gNodeB in 5G). 117 Along with these WAVE standards and C-V2X standards, regardless of a 118 wireless access technology under the IP stack of a vehicle, vehicular 119 networks can operate IP mobility with IPv6 [RFC8200] and Mobile IPv6 120 protocols (e.g., Mobile IPv6 (MIPv6) [RFC6275], Proxy MIPv6 (PMIPv6) 121 [RFC5213], Distributed Mobility Management (DMM) [RFC7333], Locator/ 122 ID Separation Protocol (LISP) [RFC6830BIS], and Asymmetric Extended 123 Route Optimization (AERO) [RFC6706BIS]). In addition, ISO has 124 approved a standard specifying the IPv6 network protocols and 125 services to be used for Communications Access for Land Mobiles (CALM) 126 [ISO-ITS-IPv6] [ISO-ITS-IPv6-AMD1]. 128 This document describes use cases and a problem statement about 129 IPv6-based vehicular networking for ITS, which is named IPv6 Wireless 130 Access in Vehicular Environments (IPWAVE). First, it introduces the 131 use cases for using V2V, V2I, and V2X networking in ITS. Next, for 132 IPv6-based vehicular networks, it makes a gap analysis of current 133 IPv6 protocols (e.g., IPv6 Neighbor Discovery, Mobility Management, 134 and Security & Privacy), and then lists up requirements for the 135 extensions of those IPv6 protocols, which are tailored to IPv6-based 136 vehicular networking. Thus, this document is intended to motivate 137 development of key protocols for IPWAVE. 139 2. Terminology 141 This document uses the terminology described in [RFC8691]. In 142 addition, the following terms are defined below: 144 o Class-Based Safety Plan: A vehicle can make a safety plan by 145 classifying the surrounding vehicles into different groups for 146 safety purposes according to the geometrical relationship among 147 them. The vehicle groups can be classified as Line-of-Sight 148 Unsafe, Non-Line-of-Sight Unsafe, and Safe groups [CASD]. 150 o Context-Awareness: A vehicle can be aware of spatial-temporal 151 mobility information (e.g., position, speed, direction, and 152 acceleration/deceleration) of surrounding vehicles for both safety 153 and non-safety uses through sensing or communication [CASD]. 155 o DMM: "Distributed Mobility Management" [RFC7333][RFC7429]. 157 o Edge Computing (EC): It is the local computing near an access 158 network (i.e., edge network) for the sake of vehicles and 159 pedestrians. 161 o Edge Computing Device (ECD): It is a computing device (or server) 162 for edge computing for the sake of vehicles and pedestrians. 164 o Edge Network (EN): It is an access network that has an IP-RSU for 165 wireless communication with other vehicles having an IP-OBU and 166 wired communication with other network devices (e.g., routers, IP- 167 RSUs, ECDs, servers, and MA). It may have a Global Positioning 168 System (GPS) radio receiver for its position recognition and the 169 localization service for the sake of vehicles. 171 o IP-OBU: "Internet Protocol On-Board Unit": An IP-OBU denotes a 172 computer situated in a vehicle (e.g., car, bicycle, autobike, 173 motor cycle, and a similar one) and a device (e.g., smartphone and 174 IoT device). It has at least one IP interface that runs in IEEE 175 802.11-OCB and has an "OBU" transceiver. Also, it may have an IP 176 interface that runs in Cellular V2X (C-V2X) [TS-23.285-3GPP] 177 [TR-22.886-3GPP][TS-23.287-3GPP]. See the definition of the term 178 "OBU" in [RFC8691]. 180 o IP-RSU: "IP Roadside Unit": An IP-RSU is situated along the road. 181 It has at least two distinct IP-enabled interfaces. The wireless 182 PHY/MAC layer of at least one of its IP-enabled interfaces is 183 configured to operate in 802.11-OCB mode. An IP-RSU communicates 184 with the IP-OBU over an 802.11 wireless link operating in OCB 185 mode. Also, it may have an IP interface that runs in C-V2X along 186 with an "RSU" transceiver. An IP-RSU is similar to an Access 187 Network Router (ANR), defined in [RFC3753], and a Wireless 188 Termination Point (WTP), defined in [RFC5415]. See the definition 189 of the term "RSU" in [RFC8691]. 191 o LiDAR: "Light Detection and Ranging". It is a scanning device to 192 measure a distance to an object by emitting pulsed laser light and 193 measuring the reflected pulsed light. 195 o Mobility Anchor (MA): A node that maintains IPv6 addresses and 196 mobility information of vehicles in a road network to support 197 their IPv6 address autoconfiguration and mobility management with 198 a binding table. An MA has End-to-End (E2E) connections (e.g., 199 tunnels) with IP-RSUs under its control for the address 200 autoconfiguration and mobility management of the vehicles. This 201 MA is similar to a Local Mobility Anchor (LMA) in PMIPv6 [RFC5213] 202 for network-based mobility management. 204 o OCB: "Outside the Context of a Basic Service Set - BSS". It is a 205 mode of operation in which a Station (STA) is not a member of a 206 BSS and does not utilize IEEE Std 802.11 authentication, 207 association, or data confidentiality [IEEE-802.11-OCB]. 209 o 802.11-OCB: It refers to the mode specified in IEEE Std 210 802.11-2016 [IEEE-802.11-OCB] when the MIB attribute 211 dot11OCBActivited is 'true'. 213 o Platooning: Moving vehicles can be grouped together to reduce air- 214 resistance for energy efficiency and reduce the number of drivers 215 such that only the leading vehicle has a driver, and the other 216 vehicles are autonomous vehicles without a driver and closely 217 follow the leading vehicle [Truck-Platooning]. 219 o Traffic Control Center (TCC): A system that manages road 220 infrastructure nodes (e.g., IP-RSUs, MAs, traffic signals, and 221 loop detectors), and also maintains vehicular traffic statistics 222 (e.g., average vehicle speed and vehicle inter-arrival time per 223 road segment) and vehicle information (e.g., a vehicle's 224 identifier, position, direction, speed, and trajectory as a 225 navigation path). TCC is part of a vehicular cloud for vehicular 226 networks. 228 o Vehicle: A Vehicle in this document is a node that has an IP-OBU 229 for wireless communication with other vehicles and IP-RSUs. It 230 has a GPS radio navigation receiver for efficient navigation. Any 231 device having an IP-OBU and a GPS receiver (e.g., smartphone and 232 table PC) can be regarded as a vehicle in this document. 234 o Vehicular Ad Hoc Network (VANET): A network that consists of 235 vehicles interconnected by wireless communication. Two vehicles 236 in a VANET can communicate with each other using other vehicles as 237 relays even where they are out of one-hop wireless communication 238 range. 240 o Vehicular Cloud: A cloud infrastructure for vehicular networks, 241 having compute nodes, storage nodes, and network forwarding 242 elements (e.g., switch and router). 244 o V2D: "Vehicle to Device". It is the wireless communication 245 between a vehicle and a device (e.g., smartphone and IoT device). 247 o V2I2D: "Vehicle to Infrastructure to Device". It is the wireless 248 communication between a vehicle and a device (e.g., smartphone and 249 IoT device) via an infrastructure node (e.g., IP-RSU). 251 o V2I2V: "Vehicle to Infrastructure to Vehicle". It is the wireless 252 communication between a vehicle and another vehicle via an 253 infrastructure node (e.g., IP-RSU). 255 o V2I2X: "Vehicle to Infrastructure to Everything". It is the 256 wireless communication between a vehicle and another entity (e.g., 257 vehicle, smartphone, and IoT device) via an infrastructure node 258 (e.g., IP-RSU). 260 o V2X: "Vehicle to Everything". It is the wireless communication 261 between a vehicle and any entity (e.g., vehicle, infrastructure 262 node, smartphone, and IoT device), including V2V, V2I, and V2D. 264 o VIP: "Vehicular Internet Protocol". It is an IPv6 extension for 265 vehicular networks including V2V, V2I, and V2X. 267 o VMM: "Vehicular Mobility Management". It is an IPv6-based 268 mobility management for vehicular networks. 270 o VND: "Vehicular Neighbor Discovery". It is an IPv6 ND extension 271 for vehicular networks. 273 o VSP: "Vehicular Security and Privacy". It is an IPv6-based 274 security and privacy for vehicular networks. 276 o WAVE: "Wireless Access in Vehicular Environments" [WAVE-1609.0]. 278 3. Use Cases 280 This section explains use cases of V2V, V2I, and V2X networking. The 281 use cases of the V2X networking exclude the ones of the V2V and V2I 282 networking, but include Vehicle-to-Pedestrian (V2P) and Vehicle-to- 283 Device (V2D). 285 IP is widely used among popular end-user devices (e.g., smartphone 286 and tablet) in the Internet. Applications (e.g., navigator 287 application) for those devices can be extended such that the V2V use 288 cases in this section can work with IPv6 as a network layer protocol 289 and IEEE 802.11-OCB as a link layer protocol. In addition, IPv6 290 security needs to be extended to support those V2V use cases in a 291 safe, secure, privacy-preserving way. 293 The use cases presented in this section serve as the description and 294 motivation for the need to extend IPv6 and its protocols to 295 facilitate "Vehicular IPv6". Section 5 summarizes the overall 296 problem statement and IPv6 requirements. Note that the adjective 297 "Vehicular" in this document is used to represent extensions of 298 existing protocols such as IPv6 Neighbor Discovery, IPv6 Mobility 299 Management (e.g., PMIPv6 [RFC5213] and DMM [RFC7429]), and IPv6 300 Security and Privacy Mechanisms rather than new "vehicular-specific" 301 functions. Refer to Section 5 for the problem statement of the 302 requirements of vehicular IPv6. 304 3.1. V2V 306 The use cases of V2V networking discussed in this section include 308 o Context-aware navigation for safe driving and collision avoidance; 310 o Cooperative adaptive cruise control in a roadway; 312 o Platooning in a highway; 314 o Cooperative environment sensing; 316 o Collision avoidance service of end systems of Urban Air Mobility 317 (UAM) [UAM-ITS]. 319 These five techniques will be important elements for autonomous 320 vehicles, which may be either terrestrial vehicles or UAM end 321 systems. 323 Context-Aware Safety Driving (CASD) navigator [CASD] can help drivers 324 to drive safely by alerting them to dangerous obstacles and 325 situations. That is, a CASD navigator displays obstacles or 326 neighboring vehicles relevant to possible collisions in real-time 327 through V2V networking. CASD provides vehicles with a class-based 328 automatic safety action plan, which considers three situations, 329 namely, the Line-of-Sight unsafe, Non-Line-of-Sight unsafe, and safe 330 situations. This action plan can be put into action among multiple 331 vehicles using V2V networking. 333 Cooperative Adaptive Cruise Control (CACC) [CA-Cruise-Control] helps 334 individual vehicles to adapt their speed autonomously through V2V 335 communication among vehicles according to the mobility of their 336 predecessor and successor vehicles in an urban roadway or a highway. 337 Thus, CACC can help adjacent vehicles to efficiently adjust their 338 speed in an interactive way through V2V networking in order to avoid 339 a collision. 341 Platooning [Truck-Platooning] allows a series (or group) of vehicles 342 (e.g., trucks) to follow each other very closely. Trucks can use V2V 343 communication in addition to forward sensors in order to maintain 344 constant clearance between two consecutive vehicles at very short 345 gaps (from 3 meters to 10 meters). Platooning can maximize the 346 throughput of vehicular traffic in a highway and reduce the gas 347 consumption because the leading vehicle can help the following 348 vehicles to experience less air resistance. 350 Cooperative-environment-sensing use cases suggest that vehicles can 351 share environmental information (e.g., air pollution, hazards/ 352 obstacles, slippery areas by snow or rain, road accidents, traffic 353 congestion, and driving behaviors of neighboring vehicles) from 354 various vehicle-mounted sensors, such as radars, LiDARs, and cameras, 355 with other vehicles and pedestrians. [Automotive-Sensing] introduces 356 millimeter-wave vehicular communication for massive automotive 357 sensing. A lot of data can be generated by those sensors, and these 358 data typically need to be routed to different destinations. In 359 addition, from the perspective of driverless vehicles, it is expected 360 that driverless vehicles can be mixed with driver-operated vehicles. 361 Through cooperative environment sensing, driver-operated vehicles can 362 use environmental information sensed by driverless vehicles for 363 better interaction with the other vehicles and environment. Vehicles 364 can also share their intended maneuvering information (e.g., lane 365 change, speed change, ramp in-and-out, cut-in, and abrupt braking) 366 with neighboring vehicles. Thus, this information sharing can help 367 the vehicles behave as more efficient traffic flows and minimize 368 unnecessary acceleration and deceleration to achieve the best ride 369 comfort. 371 A collision avoidance service of UAM end systems in air can be 372 envisioned as a use case in air vehicular environments. This use 373 case is similar to the context-aware navigator for terrestrial 374 vehicles. Through V2V coordination, those UAM end systems (e.g., 375 drones) can avoid a dangerous situation (e.g., collision) in three- 376 dimensional space rather than two-dimensional space for terrestrial 377 vehicles. Also, UAM end systems (e.g., flying car) with only a few 378 meters off the ground can communicate with terrestrial vehicles with 379 wireless communication technologies (e.g., DSRC, LTE, and C-V2X). 380 Thus, V2V means any vehicle to any vehicle, whether the vehicles are 381 ground-level or not. 383 To encourage more vehicles to participate in this cooperative 384 environmental sensing, a reward system will be needed. Sensing 385 activities of each vehicle need to be logged in either a central way 386 through a logging server (e.g., TCC) in the vehicular cloud or a 387 distributed way (e.g., blockchain [Bitcoin]) through other vehicles 388 or infrastructure. In the case of a blockchain, each sensing message 389 from a vehicle can be treated as a transaction and the neighboring 390 vehicles can play the role of peers in a consensus method of a 391 blockchain [Bitcoin][Vehicular-BlockChain]. 393 The existing IPv6 protocol must be augmented through the addition of 394 an Overlay Multilink Network (OMNI) Interface [OMNI] and/or protocol 395 changes in order to support wireless single-hop V2V communications as 396 well as wireless multihop V2V communications. Thus, the IPv6 needs 397 to support both single-hop and multihop communications in a wireless 398 medium so that vehicles can communicate with each other by V2V 399 communications to share either an emergency situation or road hazard 400 in a highway. 402 To support applications of these V2V use cases, the functions of IPv6 403 such as VND and VSP are prerequisites for IPv6-based packet exchange 404 and secure, safe communication between two vehicles. 406 3.2. V2I 408 The use cases of V2I networking discussed in this section include 410 o Navigation service; 412 o Energy-efficient speed recommendation service; 414 o Accident notification service; 416 o Electric vehicle (EV) charging service; 418 o UAM navigation service with efficient battery charging. 420 A navigation service, for example, the Self-Adaptive Interactive 421 Navigation Tool(SAINT) [SAINT], using V2I networking interacts with a 422 TCC for the large-scale/long-range road traffic optimization and can 423 guide individual vehicles along appropriate navigation paths in real 424 time. The enhanced version of SAINT [SAINTplus] can give fast moving 425 paths to emergency vehicles (e.g., ambulance and fire engine) to let 426 them reach an accident spot while redirecting other vehicles near the 427 accident spot into efficient detour paths. 429 Either a TCC or an ECD can recommend an energy-efficient speed to a 430 vehicle that depends on its traffic environment and traffic signal 431 scheduling [SignalGuru]. For example, when a vehicle approaches an 432 intersection area and a red traffic light for the vehicle becomes 433 turned on, it needs to reduce its speed to save fuel consumption. In 434 this case, either a TCC or an ECD, which has the up-to-date 435 trajectory of the vehicle and the traffic light schedule, can notify 436 the vehicle of an appropriate speed for fuel efficiency. 437 [Fuel-Efficient] studies fuel-efficient route and speed plans for 438 platooned trucks. 440 The emergency communication between accident vehicles (or emergency 441 vehicles) and a TCC can be performed via either IP-RSU or 4G-LTE 442 networks. The First Responder Network Authority (FirstNet) 443 [FirstNet] is provided by the US government to establish, operate, 444 and maintain an interoperable public safety broadband network for 445 safety and security network services, e.g., emergency calls. The 446 construction of the nationwide FirstNet network requires each state 447 in the US to have a Radio Access Network (RAN) that will connect to 448 the FirstNet's network core. The current RAN is mainly constructed 449 using 4G-LTE for the communication between a vehicle and an 450 infrastructure node (i.e., V2I) [FirstNet-Report], but it is expected 451 that DSRC-based vehicular networks [DSRC] will be available for V2I 452 and V2V in the near future. 454 An EV charging service with V2I can facilitates the efficient battery 455 charging of EVs. In the case where an EV charging station is 456 connected to an IP-RSU, an EV can be guided toward the deck of the EV 457 charging station through a battery charging server connected to the 458 IP-RSU. In addition to this EV charging service, other value-added 459 services (e.g., air firmware/software update and media streaming) can 460 be provided to an EV while it is charging its battery at the EV 461 charging station. 463 A UAM navigation service with efficient battery charging can make the 464 battery charging schedule of UAM end systems (e.g., drone) for long- 465 distance flying [CBDN]. For this battery charging schedule, a UAM 466 end system can communicate with an infrastructure node (e.g., IP-RSU) 467 toward a cloud server via V2I communications. This cloud server can 468 coordinate the battery charging schedules of multiple UAM end systems 469 for their efficient navigation path, considering flight time from 470 their current position to a battery charging station, waiting time in 471 a waiting queue at the station, and battery charging time at the 472 station. 474 The existing IPv6 protocol must be augmented through the addition of 475 an OMNI interface and/or protocol changes in order to support 476 wireless multihop V2I communications in a highway where RSUs are 477 sparsely deployed, so a vehicle can reach the wireless coverage of an 478 RSU through the multihop data forwarding of intermediate vehicles. 479 Thus, IPv6 needs to be extended for multihop V2I communications. 481 To support applications of these V2I use cases, the functions of IPv6 482 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 483 exchange, transport-layer session continuity, and secure, safe 484 communication between a vehicle and a server in the vehicular cloud. 486 3.3. V2X 488 The use case of V2X networking discussed in this section is for a 489 pedestrian protection service. 491 A pedestrian protection service, such as Safety-Aware Navigation 492 Application (SANA) [SANA], using V2I2P networking can reduce the 493 collision of a vehicle and a pedestrian carrying a smartphone 494 equipped with a network device for wireless communication (e.g., Wi- 495 Fi) with an IP-RSU. Vehicles and pedestrians can also communicate 496 with each other via an IP-RSU. An edge computing device behind the 497 IP-RSU can collect the mobility information from vehicles and 498 pedestrians, compute wireless communication scheduling for the sake 499 of them. This scheduling can save the battery of each pedestrian's 500 smartphone by allowing it to work in sleeping mode before the 501 communication with vehicles, considering their mobility. 503 For Vehicle-to-Pedestrian (V2P), a vehicle can directly communicate 504 with a pedestrian's smartphone by V2X without IP-RSU relaying. 505 Light-weight mobile nodes such as bicycles may also communicate 506 directly with a vehicle for collision avoidance using V2V. 508 The existing IPv6 protocol must be augmented through the addition of 509 an OMNI interface and/or protocol changes in order to support 510 wireless multihop V2X (or V2I2X) communications in an urban road 511 network where RSUs are deployed at intersections, so a vehicle (or a 512 pedestrian's smartphone) can reach the wireless coverage of an RSU 513 through the multihop data forwarding of intermediate vehicles (or 514 pedestrians' smartphones). Thus, IPv6 needs to be extended for 515 multihop V2X (or V2I2X) communications. 517 To support applications of these V2X use cases, the functions of IPv6 518 such as VND, VMM, and VSP are prerequisites for IPv6-based packet 519 exchange, transport-layer session continuity, and secure, safe 520 communication between a vehicle and a pedestrian either directly or 521 indirectly via an IP-RSU. 523 4. Vehicular Networks 525 This section describes an example vehicular network architecture 526 supporting V2V, V2I, and V2X communications in vehicular networks. 527 It describes an internal network within a vehicle or an edge network 528 (called EN). It explains not only the internetworking between the 529 internal networks of a vehicle and an EN via wireless links, but also 530 the internetworking between the internal networks of two vehicles via 531 wireless links. 533 Traffic Control Center in Vehicular Cloud 534 ******************************************* 535 +-------------+ * * 536 |Corresponding| * +-----------------+ * 537 | Node |<->* | Mobility Anchor | * 538 +-------------+ * +-----------------+ * 539 * ^ * 540 * | * 541 * v * 542 ******************************************* 543 ^ ^ ^ 544 | | | 545 | | | 546 v v v 547 +---------+ +---------+ +---------+ 548 | IP-RSU1 |<--------->| IP-RSU2 |<--------->| IP-RSU3 | 549 +---------+ +---------+ +---------+ 550 ^ ^ ^ 551 : : : 552 +-----------------+ +-----------------+ +-----------------+ 553 | : V2I | | : V2I | | : V2I | 554 | v | | v | | v | 555 +--------+ | +--------+ | | +--------+ | | +--------+ | 556 |Vehicle1|===> |Vehicle2|===>| | |Vehicle3|===>| | |Vehicle4|===>| 557 +--------+<...>+--------+<........>+--------+ | | +--------+ | 558 V2V ^ V2V ^ | | ^ | 559 | : V2V | | : V2V | | : V2V | 560 | v | | v | | v | 561 | +--------+ | | +--------+ | | +--------+ | 562 | |Vehicle5|===> | | |Vehicle6|===>| | |Vehicle7|==>| 563 | +--------+ | | +--------+ | | +--------+ | 564 +-----------------+ +-----------------+ +-----------------+ 565 Subnet1 Subnet2 Subnet3 566 (Prefix1) (Prefix2) (Prefix3) 568 <----> Wired Link <....> Wireless Link ===> Moving Direction 570 Figure 1: An Example Vehicular Network Architecture for V2I and V2V 572 4.1. Vehicular Network Architecture 574 Figure 1 shows an example vehicular network architecture for V2I and 575 V2V in a road network [OMNI]. The vehicular network architecture 576 contains vehicles (including IP-OBU), IP-RSUs, Mobility Anchor, 577 Traffic Control Center, and Vehicular Cloud as components. Note that 578 the components of the vehicular network architecture can be mapped to 579 those of an IP-based aeronautical network architecture in [OMNI], as 580 shown in Figure 2. 582 +-------------------+------------------------------------+ 583 | Vehicular Network | Aeronautical Network | 584 +===================+====================================+ 585 | IP-RSU | Access Router (AR) | 586 +-------------------+------------------------------------+ 587 | Vehicle (IP-OBU) | Mobile Node (MN) | 588 +-------------------+------------------------------------+ 589 | Moving Network | End User Network (EUN) | 590 +-------------------+------------------------------------+ 591 | Mobility Anchor | Mobility Service Endpoint (MSE) | 592 +-------------------+------------------------------------+ 593 | Vehicular Cloud | Internetwork (INET) Routing System | 594 +-------------------+------------------------------------+ 596 Figure 2: Mapping between Vehicular Network Components and 597 Aeronautical Network Components 599 These components are not mandatory, and they can be deployed into 600 vehicular networks in various ways. Some of them (e.g., Mobility 601 Anchor, Traffic Control Center, and Vehicular Cloud) may not be 602 needed for the vehicular networks according to target use cases in 603 Section 3. 605 An existing network architecture (e.g., an IP-based aeronautical 606 network architecture [OMNI][UAM-ITS], a network architecture of 607 PMIPv6 [RFC5213], and a low-power and lossy network architecture 608 [RFC6550]) can be extended to a vehicular network architecture for 609 multihop V2V, V2I, and V2X, as shown in Figure 1. In a highway 610 scenario, a vehicle may not access an RSU directly because of the 611 distance of the DSRC coverage (up to 1 km). For example, the OMNI 612 interface and/or RPL (IPv6 Routing Protocol for Low-Power and Lossy 613 Networks) [RFC6550] can be extended to support a multihop V2I since a 614 vehicle can take advantage of other vehicles as relay nodes to reach 615 the RSU. Also, RPL can be extended to support both multihop V2V and 616 V2X in the similar way. 618 Wireless communications needs to be considered for end systems for 619 Urban Air Mobility (UAM) such as flying cars and taxis [UAM-ITS]. 621 These UAM end systems may have multiple wireless transmission media 622 interfaces (e.g., cellular, communications satellite (SATCOM), short- 623 range omni-directional interfaces), which are offered by different 624 data link service providers. To support not only the mobility 625 management of the UAM end systems, but also the multihop and 626 multilink communications of the UAM interfaces, the UAM end systems 627 can employ an Overlay Multilink Network (OMNI) interface [OMNI] as a 628 virtual Non-Broadcast Multiple Access (NBMA) connection to a serving 629 ground domain infrastructure. This infrastructure can be configured 630 over the underlying data links. The OMNI interface and its link 631 model provide a means of multilink, multihop and mobility 632 coordination to the legacy IPv6 ND messaging [RFC4861] according to 633 the NBMA principle. Thus, the OMNI link model can support efficient 634 UAM internetworking services without additional mobility messaging, 635 and without any modification to the IPv6 ND messaging services or 636 link model. 638 As shown in this figure, IP-RSUs as routers and vehicles with IP-OBU 639 have wireless media interfaces for VANET. Furthermore, the wireless 640 media interfaces are autoconfigured with a global IPv6 prefix (e.g., 641 2001:DB8:1:1::/64) to support both V2V and V2I networking. Note that 642 2001:DB8::/32 is a documentation prefix [RFC3849] for example 643 prefixes in this document, and also that any routable IPv6 address 644 needs to be routable in a VANET and a vehicular network including IP- 645 RSUs. 647 In Figure 1, three IP-RSUs (IP-RSU1, IP-RSU2, and IP-RSU3) are 648 deployed in the road network and are connected with each other 649 through the wired networks (e.g., Ethernet). A Traffic Control 650 Center (TCC) is connected to the Vehicular Cloud for the management 651 of IP-RSUs and vehicles in the road network. A Mobility Anchor (MA) 652 may be located in the TCC as a mobility management controller. 653 Vehicle2, Vehicle3, and Vehicle4 are wirelessly connected to IP-RSU1, 654 IP-RSU2, and IP-RSU3, respectively. The three wireless networks of 655 IP-RSU1, IP-RSU2, and IP-RSU3 can belong to three different subnets 656 (i.e., Subnet1, Subnet2, and Subnet3), respectively. Those three 657 subnets use three different prefixes (i.e., Prefix1, Prefix2, and 658 Prefix3). 660 Multiple vehicles under the coverage of an RSU share a prefix such 661 that mobile nodes share a prefix of a Wi-Fi access point in a 662 wireless LAN. This is a natural characteristic in infrastructure- 663 based wireless networks. For example, in Figure 1, two vehicles 664 (i.e., Vehicle2, and Vehicle5) can use Prefix 1 to configure their 665 IPv6 global addresses for V2I communication. Alternatively, mobile 666 nodes can employ an OMNI interface and use their own IPv6 Unique 667 Local Addresses (ULAs) [RFC4193] over the wireless network without 668 requiring the messaging of IPv6 Stateless Address Autoconfiguration 669 (SLAAC) [RFC4862], which uses an on-link prefix provided by the 670 (visited) wireless LAN; this technique is known as "Bring-Your-Own- 671 Addresses". 673 A single subnet prefix announced by an RSU can span multiple vehicles 674 in VANET. For example, in Figure 1, for Prefix 1, three vehicles 675 (i.e., Vehicle1, Vehicle2, and Vehicle5) can construct a connected 676 VANET. Also, for Prefix 2, two vehicles (i.e., Vehicle3 and 677 Vehicle6) can construct another connected VANET, and for Prefix 3, 678 two vehicles (i.e., Vehicle4 and Vehicle7) can construct another 679 connected VANET. Alternatively, each vehicle could employ an OMNI 680 interface with their own ULAs such that no topologically-oriented 681 subnet prefixes need be announced by the RSU. 683 In wireless subnets in vehicular networks (e.g., Subnet1 and Subnet2 684 in Figure 1), vehicles can construct a connected VANET (with an 685 arbitrary graph topology) and can communicate with each other via V2V 686 communication. Vehicle1 can communicate with Vehicle2 via V2V 687 communication, and Vehicle2 can communicate with Vehicle3 via V2V 688 communication because they are within the wireless communication 689 range of each other. On the other hand, Vehicle3 can communicate 690 with Vehicle4 via the vehicular infrastructure (i.e., IP-RSU2 and IP- 691 RSU3) by employing V2I (i.e., V2I2V) communication because they are 692 not within the wireless communication range of each other. 694 For IPv6 packets transported over IEEE 802.11-OCB, [RFC8691] 695 specifies several details, including Maximum Transmission Unit (MTU), 696 frame format, link-local address, address mapping for unicast and 697 multicast, stateless autoconfiguration, and subnet structure. An 698 Ethernet Adaptation (EA) layer is in charge of transforming some 699 parameters between the IEEE 802.11 MAC layer and the IPv6 network 700 layer, which is located between the IEEE 802.11-OCB's logical link 701 control layer and the IPv6 network layer. This IPv6 over 802.11-OCB 702 can be used for both V2V and V2I in IPv6-based vehicular networks. 704 An IPv6 mobility solution is needed for the guarantee of 705 communication continuity in vehicular networks so that a vehicle's 706 TCP session can be continued, or UDP packets can be delivered to a 707 vehicle as a destination without loss while it moves from an IP-RSU's 708 wireless coverage to another IP-RSU's wireless coverage. In 709 Figure 1, assuming that Vehicle2 has a TCP session (or a UDP session) 710 with a corresponding node in the vehicular cloud, Vehicle2 can move 711 from IP-RSU1's wireless coverage to IP-RSU2's wireless coverage. In 712 this case, a handover for Vehicle2 needs to be performed by either a 713 host-based mobility management scheme (e.g., MIPv6 [RFC6275]) or a 714 network-based mobility management scheme (e.g., PMIPv6 [RFC5213] and 715 AERO [RFC6706BIS]). 717 In the host-based mobility scheme (e.g., MIPv6), an IP-RSU plays a 718 role of a home agent. On the other hand, in the network-based 719 mobility scheme (e.g., PMIPv6, an MA plays a role of a mobility 720 management controller such as a Local Mobility Anchor (LMA) in 721 PMIPv6, which also serves vehicles as a home agent, and an IP-RSU 722 plays a role of an access router such as a Mobile Access Gateway 723 (MAG) in PMIPv6 [RFC5213]. The host-based mobility scheme needs 724 client functionality in IPv6 stack of a vehicle as a mobile node for 725 mobility signaling message exchange between the vehicle and home 726 agent. On the other hand, the network-based mobility scheme does not 727 need such a client functionality for a vehicle because the network 728 infrastructure node (e.g., MAG in PMIPv6) as a proxy mobility agent 729 handles the mobility signaling message exchange with the home agent 730 (e.g., LMA in PMIPv6) for the sake of the vehicle. 732 There are a scalability issue and a route optimization issue in the 733 network-based mobility scheme (e.g., PMIPv6) when an MA covers a 734 large vehicular network governing many IP-RSUs. In this case, a 735 distributed mobility scheme (e.g., DMM [RFC7429]) can mitigate the 736 scalability issue by distributing multiple MAs in the vehicular 737 network such that they are positioned closer to vehicles for route 738 optimization and bottleneck mitigation in a central MA in the 739 network-based mobility scheme. All these mobility approaches (i.e., 740 a host-based mobility scheme, network-based mobility scheme, and 741 distributed mobility scheme) and a hybrid approach of a combination 742 of them need to provide an efficient mobility service to vehicles 743 moving fast and moving along with the relatively predictable 744 trajectories along the roadways. 746 In vehicular networks, the control plane can be separated from the 747 data plane for efficient mobility management and data forwarding by 748 using the concept of Software-Defined Networking (SDN) 749 [RFC7149][DMM-FPC]. Note that Forwarding Policy Configuration (FPC) 750 in [DMM-FPC], which is a flexible mobility management system, can 751 manage the separation of data-plane and control-plane in DMM. In 752 SDN, the control plane and data plane are separated for the efficient 753 management of forwarding elements (e.g., switches and routers) where 754 an SDN controller configures the forwarding elements in a centralized 755 way and they perform packet forwarding according to their forwarding 756 tables that are configured by the SDN controller. An MA as an SDN 757 controller needs to efficiently configure and monitor its IP-RSUs and 758 vehicles for mobility management, location management, and security 759 services. 761 The mobility information of a GPS receiver mounted in its vehicle 762 (e.g., position, speed, and direction) can be used to accommodate 763 mobility-aware proactive handover schemes, which can perform the 764 handover of a vehicle according to its mobility and the wireless 765 signal strength of a vehicle and an IP-RSU in a proactive way. 767 Vehicles can use the TCC as their Home Network having a home agent 768 for mobility management as in MIPv6 [RFC6275] and PMIPv6 [RFC5213], 769 so the TCC (or an MA inside the TCC) maintains the mobility 770 information of vehicles for location management. IP tunneling over 771 the wireless link should be avoided for performance efficiency. 772 Also, in vehicular networks, asymmetric links sometimes exist and 773 must be considered for wireless communications such as V2V and V2I. 775 4.2. V2I-based Internetworking 777 This section discusses the internetworking between a vehicle's 778 internal network (i.e., moving network) and an EN's internal network 779 (i.e., fixed network) via V2I communication. The internal network of 780 a vehicle is nowadays constructed with Ethernet by many automotive 781 vendors [In-Car-Network]. Note that an EN can accommodate multiple 782 routers (or switches) and servers (e.g., ECDs, navigation server, and 783 DNS server) in its internal network. 785 A vehicle's internal network often uses Ethernet to interconnect 786 Electronic Control Units (ECUs) in the vehicle. The internal network 787 can support Wi-Fi and Bluetooth to accommodate a driver's and 788 passenger's mobile devices (e.g., smartphone or tablet). The network 789 topology and subnetting depend on each vendor's network configuration 790 for a vehicle and an EN. It is reasonable to consider the 791 interaction between the internal network and an external network 792 within another vehicle or an EN. 794 +-----------------+ 795 (*)<........>(*) +----->| Vehicular Cloud | 796 (2001:DB8:1:1::/64) | | | +-----------------+ 797 +------------------------------+ +---------------------------------+ 798 | v | | v v | 799 | +-------+ +-------+ | | +-------+ +-------+ | 800 | | Host1 | |IP-OBU1| | | |IP-RSU1| | Host3 | | 801 | +-------+ +-------+ | | +-------+ +-------+ | 802 | ^ ^ | | ^ ^ | 803 | | | | | | | | 804 | v v | | v v | 805 | ---------------------------- | | ------------------------------- | 806 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:20:1::/64 | 807 | | | | | | 808 | v | | v | 809 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 810 | | Host2 | |Router1| | | |Router2| |Server1|...|ServerN| | 811 | +-------+ +-------+ | | +-------+ +-------+ +-------+ | 812 | ^ ^ | | ^ ^ ^ | 813 | | | | | | | | | 814 | v v | | v v v | 815 | ---------------------------- | | ------------------------------- | 816 | 2001:DB8:10:2::/64 | | 2001:DB8:20:2::/64 | 817 +------------------------------+ +---------------------------------+ 818 Vehicle1 (Moving Network1) EN1 (Fixed Network1) 820 <----> Wired Link <....> Wireless Link (*) Antenna 822 Figure 3: Internetworking between Vehicle and Edge Network 824 As shown in Figure 3, as internal networks, a vehicle's moving 825 network and an EN's fixed network are self-contained networks having 826 multiple subnets and having an edge router (e.g., IP-OBU and IP-RSU) 827 for the communication with another vehicle or another EN. The 828 internetworking between two internal networks via V2I communication 829 requires the exchange of the network parameters and the network 830 prefixes of the internal networks. For the efficiency, the network 831 prefixes of the internal networks (as a moving network) in a vehicle 832 need to be delegated and configured automatically. Note that a 833 moving network's network prefix can be called a Mobile Network Prefix 834 (MNP) [OMNI]. 836 Figure 3 also shows the internetworking between the vehicle's moving 837 network and the EN's fixed network. There exists an internal network 838 (Moving Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and 839 Host2), and two routers (IP-OBU1 and Router1). There exists another 840 internal network (Fixed Network1) inside EN1. EN1 has one host 841 (Host3), two routers (IP-RSU1 and Router2), and the collection of 842 servers (Server1 to ServerN) for various services in the road 843 networks, such as the emergency notification and navigation. 844 Vehicle1's IP-OBU1 (as a mobile router) and EN1's IP-RSU1 (as a fixed 845 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 846 V2I networking. Thus, a host (Host1) in Vehicle1 can communicate 847 with a server (Server1) in EN1 for a vehicular service through 848 Vehicle1's moving network, a wireless link between IP-OBU1 and IP- 849 RSU1, and EN1's fixed network. 851 For the IPv6 communication between an IP-OBU and an IP-RSU or between 852 two neighboring IP-OBUs, they need to know the network parameters, 853 which include MAC layer and IPv6 layer information. The MAC layer 854 information includes wireless link layer parameters, transmission 855 power level, and the MAC address of an external network interface for 856 the internetworking with another IP-OBU or IP-RSU. The IPv6 layer 857 information includes the IPv6 address and network prefix of an 858 external network interface for the internetworking with another IP- 859 OBU or IP-RSU. 861 Through the mutual knowledge of the network parameters of internal 862 networks, packets can be transmitted between the vehicle's moving 863 network and the EN's fixed network. Thus, V2I requires an efficient 864 protocol for the mutual knowledge of network parameters. 866 As shown in Figure 3, the addresses used for IPv6 transmissions over 867 the wireless link interfaces for IP-OBU and IP-RSU can be either 868 global IPv6 addresses, or IPv6 ULAs as long as IPv6 packets can be 869 routed within vehicular networks [OMNI]. When global IPv6 addresses 870 are used, wireless interface configuration and control overhead for 871 Duplicate Address Detection (DAD) [RFC4862] and Multicast Listener 872 Discovery (MLD) [RFC2710][RFC3810] should be minimized to support V2I 873 and V2X communications for vehicles moving fast along roadways; when 874 ULAs and the OMNI interface are used, no DAD nor MLD messaging is 875 needed. 877 4.3. V2V-based Internetworking 879 This section discusses the internetworking between the moving 880 networks of two neighboring vehicles via V2V communication. 882 (*)<..........>(*) 883 (2001:DB8:1:1::/64) | | 884 +------------------------------+ +------------------------------+ 885 | v | | v | 886 | +-------+ +-------+ | | +-------+ +-------+ | 887 | | Host1 | |IP-OBU1| | | |IP-OBU2| | Host3 | | 888 | +-------+ +-------+ | | +-------+ +-------+ | 889 | ^ ^ | | ^ ^ | 890 | | | | | | | | 891 | v v | | v v | 892 | ---------------------------- | | ---------------------------- | 893 | 2001:DB8:10:1::/64 ^ | | ^ 2001:DB8:30:1::/64 | 894 | | | | | | 895 | v | | v | 896 | +-------+ +-------+ | | +-------+ +-------+ | 897 | | Host2 | |Router1| | | |Router2| | Host4 | | 898 | +-------+ +-------+ | | +-------+ +-------+ | 899 | ^ ^ | | ^ ^ | 900 | | | | | | | | 901 | v v | | v v | 902 | ---------------------------- | | ---------------------------- | 903 | 2001:DB8:10:2::/64 | | 2001:DB8:30:2::/64 | 904 +------------------------------+ +------------------------------+ 905 Vehicle1 (Moving Network1) Vehicle2 (Moving Network2) 907 <----> Wired Link <....> Wireless Link (*) Antenna 909 Figure 4: Internetworking between Two Vehicles 911 Figure 4 shows the internetworking between the moving networks of two 912 neighboring vehicles. There exists an internal network (Moving 913 Network1) inside Vehicle1. Vehicle1 has two hosts (Host1 and Host2), 914 and two routers (IP-OBU1 and Router1). There exists another internal 915 network (Moving Network2) inside Vehicle2. Vehicle2 has two hosts 916 (Host3 and Host4), and two routers (IP-OBU2 and Router2). Vehicle1's 917 IP-OBU1 (as a mobile router) and Vehicle2's IP-OBU2 (as a mobile 918 router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC) for 919 V2V networking. Alternatively, Vehicle1 and Vehicle2 employ an OMNI 920 interface and use IPv6 ULAs for V2V networking. Thus, a host (Host1) 921 in Vehicle1 can communicate with another host (Host3) in Vehicle2 for 922 a vehicular service through Vehicle1's moving network, a wireless 923 link between IP-OBU1 and IP-OBU2, and Vehicle2's moving network. 925 As a V2V use case in Section 3.1, Figure 5 shows the linear network 926 topology of platooning vehicles for V2V communications where Vehicle3 927 is the leading vehicle with a driver, and Vehicle2 and Vehicle1 are 928 the following vehicles without drivers. 930 (*)<..................>(*)<..................>(*) 931 | | | 932 +-----------+ +-----------+ +-----------+ 933 | | | | | | 934 | +-------+ | | +-------+ | | +-------+ | 935 | |IP-OBU1| | | |IP-OBU2| | | |IP-OBU3| | 936 | +-------+ | | +-------+ | | +-------+ | 937 | ^ | | ^ | | ^ | 938 | | |=====> | | |=====> | | |=====> 939 | v | | v | | v | 940 | +-------+ | | +-------+ | | +-------+ | 941 | | Host1 | | | | Host2 | | | | Host3 | | 942 | +-------+ | | +-------+ | | +-------+ | 943 | | | | | | 944 +-----------+ +-----------+ +-----------+ 945 Vehicle1 Vehicle2 Vehicle3 947 <----> Wired Link <....> Wireless Link ===> Moving Direction 948 (*) Antenna 950 Figure 5: Multihop Internetworking between Two Vehicle Networks 952 As shown in Figure 5, multihop internetworking is feasible among the 953 moving networks of three vehicles in the same VANET. For example, 954 Host1 in Vehicle1 can communicate with Host3 in Vehicle3 via IP-OBU1 955 in Vehicle1, IP-OBU2 in Vehicle2, and IP-OBU3 in Vehicle3 in the 956 linear network, as shown in the figure. 958 5. Problem Statement 960 In order to specify protocols using the architecture mentioned in 961 Section 4.1, IPv6 core protocols have to be adapted to overcome 962 certain challenging aspects of vehicular networking. Since the 963 vehicles are likely to be moving at great speed, protocol exchanges 964 need to be completed in a time relatively short compared to the 965 lifetime of a link between a vehicle and an IP-RSU, or between two 966 vehicles. 968 Note that if two vehicles are moving in the opposite directions in a 969 roadway, the relative speed of this case is two times the relative 970 speed of a vehicle passing through an RSU. The time constraint of a 971 wireless link between two nodes needs to be considered because it may 972 affect the lifetime of a session involving the link. 974 The lifetime of a session varies depending on the session's type such 975 as a web surfing, voice call over IP, and DNS query. Regardless of a 976 session's type, to guide all the IPv6 packets to their destination 977 host, IP mobility should be supported for the session. 979 Thus, the time constraint of a wireless link has a major impact on 980 IPv6 Neighbor Discovery (ND). Mobility Management (MM) is also 981 vulnerable to disconnections that occur before the completion of 982 identity verification and tunnel management. This is especially true 983 given the unreliable nature of wireless communication. This section 984 presents key topics such as neighbor discovery and mobility 985 management. 987 5.1. Neighbor Discovery 989 IPv6 ND [RFC4861][RFC4862] is a core part of the IPv6 protocol suite. 990 IPv6 ND is designed for link types including point-to-point, 991 multicast-capable (e.g., Ethernet) and Non-Broadcast Multiple Access 992 (NBMA). It assumes the efficient and reliable support of multicast 993 and unicast from the link layer for various network operations such 994 as MAC Address Resolution (AR), DAD, MLD and Neighbor Unreachability 995 Detection (NUD). 997 Vehicles move quickly within the communication coverage of any 998 particular vehicle or IP-RSU. Before the vehicles can exchange 999 application messages with each other, they need to be configured with 1000 a link-local IPv6 address or a global IPv6 address, and run IPv6 ND. 1002 The requirements for IPv6 ND for vehicular networks are efficient DAD 1003 and NUD operations. An efficient DAD is required to reduce the 1004 overhead of the DAD packets during a vehicle's travel in a road 1005 network, which guaranteeing the uniqueness of a vehicle's global IPv6 1006 address. An efficient NUD is required to reduce the overhead of the 1007 NUD packets during a vehicle's travel in a road network, which 1008 guaranteeing the accurate neighborhood information of a vehicle in 1009 terms of adjacent vehicles and RSUs. 1011 The legacy DAD assumes that a node with an IPv6 address can reach any 1012 other node with the scope of its address at the time it claims its 1013 address, and can hear any future claim for that address by another 1014 party within the scope of its address for the duration of the address 1015 ownership. However, the partitioning and merging of VANETs makes 1016 this assumption frequently invalid in vehicular networks. The 1017 merging and partitioning of VANETs frequently occurs in vehicular 1018 networks. This merging and partitioning should be considered for the 1019 IPv6 ND such as IPv6 Stateless Address Autoconfiguration (SLAAC) 1020 [RFC4862]. Due to the merging of VANETs, two IPv6 addresses may 1021 conflict with each other though they were unique before the merging. 1022 Also, the partitioning of a VANET may make vehicles with the same 1023 prefix be physically unreachable. Also, SLAAC needs to prevent IPv6 1024 address duplication due to the merging of VANETs. According to the 1025 merging and partitioning, a destination vehicle (as an IPv6 host) 1026 needs to be distinguished as either an on-link host or an off-link 1027 host even though the source vehicle uses the same prefix as the 1028 destination vehicle. 1030 To efficiently prevent IPv6 address duplication due to the VANET 1031 partitioning and merging from happening in vehicular networks, the 1032 vehicular networks need to support a vehicular-network-wide DAD by 1033 defining a scope that is compatible with the legacy DAD. In this 1034 case, two vehicles can communicate with each other when there exists 1035 a communication path over VANET or a combination of VANETs and IP- 1036 RSUs, as shown in Figure 1. By using the vehicular-network-wide DAD, 1037 vehicles can assure that their IPv6 addresses are unique in the 1038 vehicular network whenever they are connected to the vehicular 1039 infrastructure or become disconnected from it in the form of VANET. 1041 ND time-related parameters such as router lifetime and Neighbor 1042 Advertisement (NA) interval need to be adjusted for vehicle speed and 1043 vehicle density. For example, the NA interval needs to be 1044 dynamically adjusted according to a vehicle's speed so that the 1045 vehicle can maintain its neighboring vehicles in a stable way, 1046 considering the collision probability with the NA messages sent by 1047 other vehicles. 1049 For IPv6-based safety applications (e.g., context-aware navigation, 1050 adaptive cruise control, and platooning) in vehicular networks, the 1051 delay-bounded data delivery is critical. IPv6 ND needs to work to 1052 support those IPv6-based safety applications efficiently. 1054 Thus, in IPv6-based vehicular networking, IPv6 ND should have minimum 1055 changes for the interoperability with the legacy IPv6 ND used in the 1056 Internet, including the DAD and NUD operations. 1058 5.1.1. Link Model 1060 A prefix model for a vehicular network needs to facilitate the 1061 communication between two vehicles with the same prefix regardless of 1062 the vehicular network topology as long as there exist bidirectional 1063 E2E paths between them in the vehicular network including VANETs and 1064 IP-RSUs. This prefix model allows vehicles with the same prefix to 1065 communicate with each other via a combination of multihop V2V and 1066 multihop V2I with VANETs and IP-RSUs. Note that the OMNI interface 1067 supports an NBMA link model where multihop V2V and V2I communications 1068 use each mobile node's ULAs without need for any DAD or MLD 1069 messaging. 1071 IPv6 protocols work under certain assumptions that do not necessarily 1072 hold for vehicular wireless access link types other than OMNI/NBMA 1073 [VIP-WAVE][RFC5889]; the rest of this section discusses implications 1074 for those link types that do not apply when the OMNI/NBMA link model 1075 is used. For instance, some IPv6 protocols assume symmetry in the 1076 connectivity among neighboring interfaces [RFC6250]. However, radio 1077 interference and different levels of transmission power may cause 1078 asymmetric links to appear in vehicular wireless links. As a result, 1079 a new vehicular link model needs to consider the asymmetry of 1080 dynamically changing vehicular wireless links. 1082 There is a relationship between a link and a prefix, besides the 1083 different scopes that are expected from the link-local and global 1084 types of IPv6 addresses. In an IPv6 link, it is assumed that all 1085 interfaces which are configured with the same subnet prefix and with 1086 on-link bit set can communicate with each other on an IPv6 link. 1087 However, the vehicular link model needs to define the relationship 1088 between a link and a prefix, considering the dynamics of wireless 1089 links and the characteristics of VANET. 1091 A VANET can have a single link between each vehicle pair within 1092 wireless communication range, as shown in Figure 5. When two 1093 vehicles belong to the same VANET, but they are out of wireless 1094 communication range, they cannot communicate directly with each 1095 other. Suppose that a global-scope IPv6 prefix (or an IPv6 ULA 1096 prefix) is assigned to VANETs in vehicular networks. Even though two 1097 vehicles in the same VANET configure their IPv6 addresses with the 1098 same IPv6 prefix, they may not communicate with each other not in one 1099 hop in the same VANET because of the multihop network connectivity 1100 between them. Thus, in this case, the concept of an on-link IPv6 1101 prefix does not hold because two vehicles with the same on-link IPv6 1102 prefix cannot communicate directly with each other. Also, when two 1103 vehicles are located in two different VANETs with the same IPv6 1104 prefix, they cannot communicate with each other. When these two 1105 VANETs converge to one VANET, the two vehicles can communicate with 1106 each other in a multihop fashion, for example, when they are Vehicle1 1107 and Vehicle3, as shown in Figure 5. 1109 From the previous observation, a vehicular link model should consider 1110 the frequent partitioning and merging of VANETs due to vehicle 1111 mobility. Therefore, the vehicular link model needs to use an on- 1112 link prefix and off-link prefix according to the network topology of 1113 vehicles such as a one-hop reachable network and a multihop reachable 1114 network (or partitioned networks). If the vehicles with the same 1115 prefix are reachable from each other in one hop, the prefix should be 1116 on-link. On the other hand, if some of the vehicles with the same 1117 prefix are not reachable from each other in one hop due to either the 1118 multihop topology in the VANET or multiple partitions, the prefix 1119 should be off-link. 1121 The vehicular link model needs to support multihop routing in a 1122 connected VANET where the vehicles with the same global-scope IPv6 1123 prefix (or the same IPv6 ULA prefix) are connected in one hop or 1124 multiple hops. It also needs to support the multihop routing in 1125 multiple connected VANETs through infrastructure nodes (e.g., IP-RSU) 1126 where they are connected to the infrastructure. For example, in 1127 Figure 1, suppose that Vehicle1, Vehicle2, and Vehicle3 are 1128 configured with their IPv6 addresses based on the same global-scope 1129 IPv6 prefix. Vehicle1 and Vehicle3 can also communicate with each 1130 other via either multihop V2V or multihop V2I2V. When Vehicle1 and 1131 Vehicle3 are connected in a VANET, it will be more efficient for them 1132 to communicate with each other directly via VANET rather than 1133 indirectly via IP-RSUs. On the other hand, when Vehicle1 and 1134 Vehicle3 are far away from direct communication range in separate 1135 VANETs and under two different IP-RSUs, they can communicate with 1136 each other through the relay of IP-RSUs via V2I2V. Thus, two 1137 separate VANETs can merge into one network via IP-RSU(s). Also, 1138 newly arriving vehicles can merge two separate VANETs into one VANET 1139 if they can play the role of a relay node for those VANETs. 1141 Thus, in IPv6-based vehicular networking, the vehicular link model 1142 should have minimum changes for interoperability with standard IPv6 1143 links in an efficient fashion to support IPv6 DAD, MLD and NUD 1144 operations. When the OMNI NBMA link model is used, there are no link 1145 model changes nor DAD/MLD messaging required. 1147 5.1.2. MAC Address Pseudonym 1149 For the protection of drivers' privacy, a pseudonym of a MAC address 1150 of a vehicle's network interface should be used, so that the MAC 1151 address can be changed periodically. However, although such a 1152 pseudonym of a MAC address can protect to some extent the privacy of 1153 a vehicle, it may not be able to resist attacks on vehicle 1154 identification by other fingerprint information, for example, the 1155 scrambler seed embedded in IEEE 802.11-OCB frames [Scrambler-Attack]. 1156 The pseudonym of a MAC address affects an IPv6 address based on the 1157 MAC address, and a transport-layer (e.g., TCP and SCTP) session with 1158 an IPv6 address pair. However, the pseudonym handling is not 1159 implemented and tested yet for applications on IP-based vehicular 1160 networking. 1162 In the ETSI standards, for the sake of security and privacy, an ITS 1163 station (e.g., vehicle) can use pseudonyms for its network interface 1164 identities (e.g., MAC address) and the corresponding IPv6 addresses 1165 [Identity-Management]. Whenever the network interface identifier 1166 changes, the IPv6 address based on the network interface identifier 1167 needs to be updated, and the uniqueness of the address needs to be 1168 checked through the DAD procedure. For vehicular networks with high 1169 mobility and density, this DAD needs to be performed efficiently with 1170 minimum overhead so that the vehicles can exchange application 1171 messages (e.g., collision avoidance and accident notification) with 1172 each other with a short interval (e.g., 0.5 second) 1173 [NHTSA-ACAS-Report]. 1175 5.1.3. Routing 1177 For multihop V2V communications in either a VANET or VANETs via IP- 1178 RSUs, a vehicular Mobile Ad Hoc Networks (MANET) routing protocol may 1179 be required to support both unicast and multicast in the links of the 1180 subnet with the same IPv6 prefix. However, it will be costly to run 1181 both vehicular ND and a vehicular ad hoc routing protocol in terms of 1182 control traffic overhead [ID-Multicast-Problems]. 1184 A routing protocol for a VANET may cause redundant wireless frames in 1185 the air to check the neighborhood of each vehicle and compute the 1186 routing information in a VANET with a dynamic network topology 1187 because the IPv6 ND is used to check the neighborhood of each 1188 vehicle. Thus, the vehicular routing needs to take advantage of the 1189 IPv6 ND to minimize its control overhead. 1191 5.2. Mobility Management 1193 The seamless connectivity and timely data exchange between two end 1194 points requires efficient mobility management including location 1195 management and handover. Most vehicles are equipped with a GPS 1196 receiver as part of a dedicated navigation system or a corresponding 1197 smartphone App. Note that the GPS receiver may not provide vehicles 1198 with accurate location information in adverse environments such as a 1199 building area or a tunnel. The location precision can be improved 1200 with assistance of the IP-RSUs or a cellular system with a GPS 1201 receiver for location information. 1203 With a GPS navigator, efficient mobility management can be performed 1204 with the help of vehicles periodically reporting their current 1205 position and trajectory (i.e., navigation path) to the vehicular 1206 infrastructure (having IP-RSUs and an MA in TCC). This vehicular 1207 infrastructure can predict the future positions of the vehicles from 1208 their mobility information (i.e., the current position, speed, 1209 direction, and trajectory) for efficient mobility management (e.g., 1210 proactive handover). For a better proactive handover, link-layer 1211 parameters, such as the signal strength of a link-layer frame (e.g., 1212 Received Channel Power Indicator (RCPI) [VIP-WAVE]), can be used to 1213 determine the moment of a handover between IP-RSUs along with 1214 mobility information. 1216 By predicting a vehicle's mobility, the vehicular infrastructure 1217 needs to better support IP-RSUs to perform efficient SLAAC, data 1218 forwarding, horizontal handover (i.e., handover in wireless links 1219 using a homogeneous radio technology), and vertical handover (i.e., 1220 handover in wireless links using heterogeneous radio technologies) in 1221 advance along with the movement of the vehicle. 1223 For example, as shown in Figure 1, when a vehicle (e.g., Vehicle2) is 1224 moving from the coverage of an IP-RSU (e.g., IP-RSU1) into the 1225 coverage of another IP-RSU (e.g., IP-RSU2) belonging to a different 1226 subnet, the IP-RSUs can proactively support the IPv6 mobility of the 1227 vehicle, while performing the SLAAC, data forwarding, and handover 1228 for the sake of the vehicle. 1230 For a mobility management scheme in a shared link, where the wireless 1231 subnets of multiple IP-RSUs share the same prefix, an efficient 1232 vehicular-network-wide DAD is required. If DHCPv6 is used to assign 1233 a unique IPv6 address to each vehicle in this shared link, the DAD is 1234 not required. On the other hand, for a mobility management scheme 1235 with a unique prefix per mobile node (e.g., PMIPv6 [RFC5213] and OMNI 1236 [OMNI]), DAD is not required because the IPv6 address of a vehicle's 1237 external wireless interface is guaranteed to be unique. There is a 1238 tradeoff between the prefix usage efficiency and DAD overhead. Thus, 1239 the IPv6 address autoconfiguration for vehicular networks needs to 1240 consider this tradeoff to support efficient mobility management. 1242 Therefore, for the proactive and seamless IPv6 mobility of vehicles, 1243 the vehicular infrastructure (including IP-RSUs and MA) needs to 1244 efficiently perform the mobility management of the vehicles with 1245 their mobility information and link-layer information. Also, in 1246 IPv6-based vehicular networking, IPv6 mobility management should have 1247 minimum changes for the interoperability with the legacy IPv6 1248 mobility management schemes such as PMIPv6, DMM, LISP, and AERO. 1250 6. Security Considerations 1252 This section discusses security and privacy for IPv6-based vehicular 1253 networking. Security and privacy are key components of IPv6-based 1254 vehicular networking along with neighbor discovery and mobility 1255 management. 1257 Security and privacy are paramount in V2I, V2V, and V2X networking. 1258 Vehicles and infrastructure must be authenticated in order to 1259 participate in vehicular networking. Also, in-vehicle devices (e.g., 1260 ECU) and a driver/passenger's mobile devices (e.g., smartphone and 1261 tablet PC) in a vehicle need to communicate with other in-vehicle 1262 devices and another driver/passenger's mobile devices in another 1263 vehicle, or other servers behind an IP-RSU in a secure way. Even 1264 though a vehicle is perfectly authenticated and legitimate, it may be 1265 hacked for running malicious applications to track and collect its 1266 and other vehicles' information. In this case, an attack mitigation 1267 process may be required to reduce the aftermath of malicious 1268 behaviors. 1270 Strong security measures shall protect vehicles roaming in road 1271 networks from the attacks of malicious nodes, which are controlled by 1272 hackers. For safe driving applications (e.g., context-aware 1273 navigation, cooperative adaptive cruise control, and platooning), as 1274 explained in Section 3.1, the cooperative action among vehicles is 1275 assumed. Malicious nodes may disseminate wrong driving information 1276 (e.g., location, speed, and direction) for disturbing safe driving. 1277 For example, a Sybil attack, which tries to confuse a vehicle with 1278 multiple false identities, may disturb a vehicle from taking a safe 1279 maneuver. 1281 Even though vehicles can be authenticated with valid certificates by 1282 an authentication server in the vehicular cloud, the authenticated 1283 vehicles may harm other vehicles, so their communication activities 1284 need to be logged in either a central way through a logging server 1285 (e.g., TCC) in the vehicular cloud or a distributed way (e.g., 1286 blockchain [Bitcoin]) along with other vehicles or infrastructure. 1287 For the non-repudiation of the harmful activities of malicious nodes, 1288 a blockchain technology can be used [Bitcoin]. Each message from a 1289 vehicle can be treated as a transaction and the neighboring vehicles 1290 can play the role of peers in a consensus method of a blockchain 1291 [Bitcoin][Vehicular-BlockChain]. For a blockchain's efficient 1292 consensus in vehicular networks having fast moving vehicles, a new 1293 consensus algorithm needs to be developed or an existing consensus 1294 algorithm needs to be enhanced. 1296 To identify malicious vehicles among vehicles, an authentication 1297 method is required. A Vehicle Identification Number (VIN) and a user 1298 certificate (e.g., X.509 certificate [RFC5280]) along with an in- 1299 vehicle device's identifier generation can be used to efficiently 1300 authenticate a vehicle or its driver (having a user certificate) 1301 through a road infrastructure node (e.g., IP-RSU) connected to an 1302 authentication server in the vehicular cloud. This authentication 1303 can be used to identify the vehicle that will communicate with an 1304 infrastructure node or another vehicle. In the case where a vehicle 1305 has an internal network (called Moving Network) and elements in the 1306 network (e.g., in-vehicle devices and a user's mobile devices), as 1307 shown in Figure 3, the elements in the network need to be 1308 authenticated individually for safe authentication. Also, Transport 1309 Layer Security (TLS) certificates [RFC8446][RFC5280] can be used for 1310 an element's authentication to allow secure E2E vehicular 1311 communications between an element in a vehicle and another element in 1312 a server in a vehicular cloud, or between an element in a vehicle and 1313 another element in another vehicle. 1315 For secure V2I communication, a secure channel (e.g., IPsec) between 1316 a mobile router (i.e., IP-OBU) in a vehicle and a fixed router (i.e., 1317 IP-RSU) in an EN needs to be established, as shown in Figure 3 1318 [RFC4301][RFC4302][RFC4303][RFC4308][RFC7296]. Also, for secure V2V 1319 communication, a secure channel (e.g., IPsec) between a mobile router 1320 (i.e., IP-OBU) in a vehicle and a mobile router (i.e., IP-OBU) in 1321 another vehicle needs to be established, as shown in Figure 4. For 1322 secure communication, an element in a vehicle (e.g., an in-vehicle 1323 device and a driver/passenger's mobile device) needs to establish a 1324 secure connection (e.g., TLS) with another element in another vehicle 1325 or another element in a vehicular cloud (e.g., a server). Even 1326 though IEEE 1609.2 [WAVE-1609.2] specifies security services for 1327 applications and management messages. This WAVE specification is 1328 optional, so if WAVE does not support the security of a WAVE frame, 1329 either the network layer or the transport layer needs to support 1330 security services for the WAVE frames. 1332 For the setup of a secure channel over IPsec or TLS, the multihop V2I 1333 communications over DSRC is required in a highway for the 1334 authentication by involving multiple intermediate vehicles as relay 1335 nodes toward an IP-RSU connected to an authentication server in the 1336 vehicular cloud. The V2I communications over 5G V2X (or LTE V2X) is 1337 required to allow a vehicle to communicate directly with a gNodeB (or 1338 eNodeB) connected to an authentication server in the vehicular cloud. 1340 To prevent an adversary from tracking a vehicle with its MAC address 1341 or IPv6 address, especially for a long-living transport-layer session 1342 (e.g., voice call over IP and video streaming service), a MAC address 1343 pseudonym needs to be provided to each vehicle; that is, each vehicle 1344 periodically updates its MAC address and its IPv6 address needs to be 1345 updated accordingly by the MAC address change [RFC4086][RFC4941]. 1346 Such an update of the MAC and IPv6 addresses should not interrupt the 1347 E2E communications between two vehicles (or between a vehicle and an 1348 IP-RSU) for a long-living transport-layer session. However, if this 1349 pseudonym is performed without strong E2E confidentiality (using 1350 either IPsec or TLS), there will be no privacy benefit from changing 1351 MAC and IPv6 addresses, because an adversary can observe the change 1352 of the MAC and IPv6 addresses and track the vehicle with those 1353 addresses. Thus, the MAC address pseudonym and the IPv6 address 1354 update should be performed with strong E2E confidentiality. 1356 For the IPv6 ND, the DAD is required to ensure the uniqueness of the 1357 IPv6 address of a vehicle's wireless interface. This DAD can be used 1358 as a flooding attack that uses the DAD-related ND packets 1359 disseminated over the VANET or vehicular networks. Thus, the 1360 vehicles and IP-RSUs need to filter out suspicious ND traffic in 1361 advance. 1363 For mobility management, a malicious vehicle can construct multiple 1364 virtual bogus vehicles, and register them with IP-RSUs and MA. This 1365 registration makes the IP-RSUs and MA waste their resources. The IP- 1366 RSUs and MA need to determine whether a vehicle is genuine or bogus 1367 in mobility management. Also, the confidentiality of control packets 1368 and data packets among IP-RSUs and MA, the E2E paths (e.g., tunnels) 1369 need to be protected by secure communication channels. In addition, 1370 to prevent bogus IP-RSUs and MA from interfering with the IPv6 1371 mobility of vehicles, mutual authentication among them needs to be 1372 performed by certificates (e.g., TLS certificate). 1374 7. IANA Considerations 1376 This document does not require any IANA actions. 1378 8. Informative References 1380 [Automotive-Sensing] 1381 Choi, J., Va, V., Gonzalez-Prelcic, N., Daniels, R., R. 1382 Bhat, C., and R. W. Heath, "Millimeter-Wave Vehicular 1383 Communication to Support Massive Automotive Sensing", 1384 IEEE Communications Magazine, December 2016. 1386 [Bitcoin] Nakamoto, S., "Bitcoin: A Peer-to-Peer Electronic Cash 1387 System", URL: https://bitcoin.org/bitcoin.pdf, May 2009. 1389 [CA-Cruise-Control] 1390 California Partners for Advanced Transportation Technology 1391 (PATH), "Cooperative Adaptive Cruise Control", Available: 1392 http://www.path.berkeley.edu/research/automated-and- 1393 connected-vehicles/cooperative-adaptive-cruise-control, 1394 2017. 1396 [CASD] Shen, Y., Jeong, J., Oh, T., and S. Son, "CASD: A 1397 Framework of Context-Awareness Safety Driving in Vehicular 1398 Networks", International Workshop on Device Centric Cloud 1399 (DC2), March 2016. 1401 [CBDN] Kim, J., Kim, S., Jeong, J., Kim, H., Park, J., and T. 1402 Kim, "CBDN: Cloud-Based Drone Navigation for Efficient 1403 Battery Charging in Drone Networks", IEEE Transactions on 1404 Intelligent Transportation Systems, November 2019. 1406 [DMM-FPC] Matsushima, S., Bertz, L., Liebsch, M., Gundavelli, S., 1407 Moses, D., and C. Perkins, "Protocol for Forwarding Policy 1408 Configuration (FPC) in DMM", draft-ietf-dmm-fpc-cpdp-13 1409 (work in progress), March 2020. 1411 [DSRC] ASTM International, "Standard Specification for 1412 Telecommunications and Information Exchange Between 1413 Roadside and Vehicle Systems - 5 GHz Band Dedicated Short 1414 Range Communications (DSRC) Medium Access Control (MAC) 1415 and Physical Layer (PHY) Specifications", 1416 ASTM E2213-03(2010), October 2010. 1418 [EU-2008-671-EC] 1419 European Union, "Commission Decision of 5 August 2008 on 1420 the Harmonised Use of Radio Spectrum in the 5875 - 5905 1421 MHz Frequency Band for Safety-related Applications of 1422 Intelligent Transport Systems (ITS)", EU 2008/671/EC, 1423 August 2008. 1425 [FirstNet] 1426 U.S. National Telecommunications and Information 1427 Administration (NTIA), "First Responder Network Authority 1428 (FirstNet)", Available: https://www.firstnet.gov/, 2012. 1430 [FirstNet-Report] 1431 First Responder Network Authority, "FY 2017: ANNUAL REPORT 1432 TO CONGRESS, Advancing Public Safety Broadband 1433 Communications", FirstNet FY 2017, December 2017. 1435 [Fuel-Efficient] 1436 van de Hoef, S., H. Johansson, K., and D. V. Dimarogonas, 1437 "Fuel-Efficient En Route Formation of Truck Platoons", 1438 IEEE Transactions on Intelligent Transportation Systems, 1439 January 2018. 1441 [ID-Multicast-Problems] 1442 Perkins, C., McBride, M., Stanley, D., Kumari, W., and JC. 1443 Zuniga, "Multicast Considerations over IEEE 802 Wireless 1444 Media", draft-ietf-mboned-ieee802-mcast-problems-11 (work 1445 in progress), December 2019. 1447 [Identity-Management] 1448 Wetterwald, M., Hrizi, F., and P. Cataldi, "Cross-layer 1449 Identities Management in ITS Stations", The 10th 1450 International Conference on ITS Telecommunications, 1451 November 2010. 1453 [IEEE-802.11-OCB] 1454 "Part 11: Wireless LAN Medium Access Control (MAC) and 1455 Physical Layer (PHY) Specifications", IEEE Std 1456 802.11-2016, December 2016. 1458 [IEEE-802.11p] 1459 "Part 11: Wireless LAN Medium Access Control (MAC) and 1460 Physical Layer (PHY) Specifications - Amendment 6: 1461 Wireless Access in Vehicular Environments", IEEE Std 1462 802.11p-2010, June 2010. 1464 [In-Car-Network] 1465 Lim, H., Volker, L., and D. Herrscher, "Challenges in a 1466 Future IP/Ethernet-based In-Car Network for Real-Time 1467 Applications", ACM/EDAC/IEEE Design Automation Conference 1468 (DAC), June 2011. 1470 [ISO-ITS-IPv6] 1471 ISO/TC 204, "Intelligent Transport Systems - 1472 Communications Access for Land Mobiles (CALM) - IPv6 1473 Networking", ISO 21210:2012, June 2012. 1475 [ISO-ITS-IPv6-AMD1] 1476 ISO/TC 204, "Intelligent Transport Systems - 1477 Communications Access for Land Mobiles (CALM) - IPv6 1478 Networking - Amendment 1", ISO 21210:2012/AMD 1:2017, 1479 September 2017. 1481 [NHTSA-ACAS-Report] 1482 National Highway Traffic Safety Administration (NHTSA), 1483 "Final Report of Automotive Collision Avoidance Systems 1484 (ACAS) Program", DOT HS 809 080, August 2000. 1486 [OMNI] Templin, F. and A. Whyman, "Transmission of IPv6 Packets 1487 over Overlay Multilink Network (OMNI) Interfaces", draft- 1488 templin-6man-omni-interface-27 (work in progress), June 1489 2020. 1491 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1492 Listener Discovery (MLD) for IPv6", RFC 2710, October 1493 1999. 1495 [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", 1496 RFC 3753, June 2004. 1498 [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery 1499 Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. 1501 [RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix 1502 Reserved for Documentation", RFC 3849, July 2004. 1504 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1505 "Randomness Requirements for Security", RFC 4086, June 1506 2005. 1508 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 1509 Addresses", RFC 4193, October 2005. 1511 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1512 Internet Protocol", RFC 4301, December 2005. 1514 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, December 1515 2005. 1517 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1518 RFC 4303, December 2005. 1520 [RFC4308] Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308, 1521 December 2005. 1523 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1524 "Neighbor Discovery for IP Version 6 (IPv6)", RFC 4861, 1525 September 2007. 1527 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1528 Address Autoconfiguration", RFC 4862, September 2007. 1530 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1531 Extensions for Stateless Address Autoconfiguration in 1532 IPv6", RFC 4941, September 2007. 1534 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1535 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1536 RFC 5213, August 2008. 1538 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1539 Housley, R., and W. Polk, "Internet X.509 Public Key 1540 Infrastructure Certificate and Certificate Revocation List 1541 (CRL) Profile", RFC 5280, May 2008. 1543 [RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And 1544 Provisioning of Wireless Access Points (CAPWAP) Protocol 1545 Specification", RFC 5415, March 2009. 1547 [RFC5889] Baccelli, E. and M. Townsley, "IP Addressing Model in Ad 1548 Hoc Networks", RFC 5889, September 2010. 1550 [RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250, May 1551 2011. 1553 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1554 Support in IPv6", RFC 6275, July 2011. 1556 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 1557 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 1558 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 1559 Lossy Networks", RFC 6550, March 2012. 1561 [RFC6706BIS] 1562 Templin, F., "Asymmetric Extended Route Optimization 1563 (AERO)", draft-templin-intarea-6706bis-58 (work in 1564 progress), June 2020. 1566 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 1567 "Neighbor Discovery Optimization for IPv6 over Low-Power 1568 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 1569 November 2012. 1571 [RFC6830BIS] 1572 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 1573 Cabellos, "The Locator/ID Separation Protocol (LISP)", 1574 draft-ietf-lisp-rfc6830bis-32 (work in progress), March 1575 2020. 1577 [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined 1578 Networking: A Perspective from within a Service Provider 1579 Environment", RFC 7149, March 2014. 1581 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1582 Kivinen, "Internet Key Exchange Protocol Version 2 1583 (IKEv2)", RFC 7296, October 2014. 1585 [RFC7333] Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen, 1586 "Requirements for Distributed Mobility Management", 1587 RFC 7333, August 2014. 1589 [RFC7429] Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ. 1590 Bernardos, "Distributed Mobility Management: Current 1591 Practices and Gap Analysis", RFC 7429, January 2015. 1593 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1594 (IPv6) Specification", RFC 8200, July 2017. 1596 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 1597 Version 1.3", RFC 8446, August 2018. 1599 [RFC8691] Benamar, N., Haerri, J., Lee, J., and T. Ernst, "Basic 1600 Support for IPv6 Networks Operating Outside the Context of 1601 a Basic Service Set over IEEE Std 802.11", RFC 8691, 1602 December 2019. 1604 [SAINT] Jeong, J., Jeong, H., Lee, E., Oh, T., and D. Du, "SAINT: 1605 Self-Adaptive Interactive Navigation Tool for Cloud-Based 1606 Vehicular Traffic Optimization", IEEE Transactions on 1607 Vehicular Technology, Vol. 65, No. 6, June 2016. 1609 [SAINTplus] 1610 Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., and D. 1611 Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+ 1612 for Emergency Service Delivery Optimization", 1613 IEEE Transactions on Intelligent Transportation Systems, 1614 June 2017. 1616 [SANA] Hwang, T. and J. Jeong, "SANA: Safety-Aware Navigation 1617 Application for Pedestrian Protection in Vehicular 1618 Networks", Springer Lecture Notes in Computer Science 1619 (LNCS), Vol. 9502, December 2015. 1621 [Scrambler-Attack] 1622 Bloessl, B., Sommer, C., Dressier, F., and D. Eckhoff, 1623 "The Scrambler Attack: A Robust Physical Layer Attack on 1624 Location Privacy in Vehicular Networks", IEEE 2015 1625 International Conference on Computing, Networking and 1626 Communications (ICNC), February 2015. 1628 [SignalGuru] 1629 Koukoumidis, E., Peh, L., and M. Martonosi, "SignalGuru: 1630 Leveraging Mobile Phones for Collaborative Traffic Signal 1631 Schedule Advisory", ACM MobiSys, June 2011. 1633 [TR-22.886-3GPP] 1634 3GPP, "Study on Enhancement of 3GPP Support for 5G V2X 1635 Services", 3GPP TR 22.886/Version 16.2.0, December 2018. 1637 [Truck-Platooning] 1638 California Partners for Advanced Transportation Technology 1639 (PATH), "Automated Truck Platooning", Available: 1640 http://www.path.berkeley.edu/research/automated-and- 1641 connected-vehicles/truck-platooning, 2017. 1643 [TS-23.285-3GPP] 1644 3GPP, "Architecture Enhancements for V2X Services", 3GPP 1645 TS 23.285/Version 16.2.0, December 2019. 1647 [TS-23.287-3GPP] 1648 3GPP, "Architecture Enhancements for 5G System (5GS) to 1649 Support Vehicle-to-Everything (V2X) Services", 3GPP 1650 TS 23.287/Version 16.2.0, March 2020. 1652 [UAM-ITS] Templin, F., "Urban Air Mobility Implications for 1653 Intelligent Transportation Systems", draft-templin-ipwave- 1654 uam-its-03 (work in progress), July 2020. 1656 [Vehicular-BlockChain] 1657 Dorri, A., Steger, M., Kanhere, S., and R. Jurdak, 1658 "BlockChain: A Distributed Solution to Automotive Security 1659 and Privacy", IEEE Communications Magazine, Vol. 55, No. 1660 12, December 2017. 1662 [VIP-WAVE] 1663 Cespedes, S., Lu, N., and X. Shen, "VIP-WAVE: On the 1664 Feasibility of IP Communications in 802.11p Vehicular 1665 Networks", IEEE Transactions on Intelligent Transportation 1666 Systems, vol. 14, no. 1, March 2013. 1668 [WAVE-1609.0] 1669 IEEE 1609 Working Group, "IEEE Guide for Wireless Access 1670 in Vehicular Environments (WAVE) - Architecture", IEEE Std 1671 1609.0-2013, March 2014. 1673 [WAVE-1609.2] 1674 IEEE 1609 Working Group, "IEEE Standard for Wireless 1675 Access in Vehicular Environments - Security Services for 1676 Applications and Management Messages", IEEE Std 1677 1609.2-2016, March 2016. 1679 [WAVE-1609.3] 1680 IEEE 1609 Working Group, "IEEE Standard for Wireless 1681 Access in Vehicular Environments (WAVE) - Networking 1682 Services", IEEE Std 1609.3-2016, April 2016. 1684 [WAVE-1609.4] 1685 IEEE 1609 Working Group, "IEEE Standard for Wireless 1686 Access in Vehicular Environments (WAVE) - Multi-Channel 1687 Operation", IEEE Std 1609.4-2016, March 2016. 1689 Appendix A. 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 B. 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 1777 Alexandre Petrescu 1778 CEA, LIST 1779 CEA Saclay 1780 Gif-sur-Yvette, Ile-de-France 91190 1781 France 1783 Phone: +33169089223 1784 EMail: Alexandre.Petrescu@cea.fr 1786 Yiwen Chris Shen 1787 Department of Computer Science & Engineering 1788 Sungkyunkwan University 1789 2066 Seobu-Ro, Jangan-Gu 1790 Suwon, Gyeonggi-Do 16419 1791 Republic of Korea 1793 Phone: +82 31 299 4106 1794 Fax: +82 31 290 7996 1795 EMail: chrisshen@skku.edu 1796 URI: http://iotlab.skku.edu/people-chris-shen.php 1798 Michelle Wetterwald 1799 FBConsulting 1800 21, Route de Luxembourg 1801 Wasserbillig, Luxembourg L-6633 1802 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