IPWAVE Working Group                                       J. Jeong, Ed.
Internet-Draft                                   Sungkyunkwan University
Intended status: Informational                          October 22,                          November 4, 2018
Expires: April 25, May 8, 2019

IP Wireless Access in Vehicular Environments (IPWAVE): Problem Statement
                             and Use Cases


   This document discusses the problem statement and use cases on IP-
   based vehicular networks, which are considered a key component of
   Intelligent Transportation Systems (ITS).  The main scenarios of
   vehicular communications are vehicle-to-vehicle (V2V), vehicle-to-
   infrastructure (V2I), and vehicle-to-everything (V2X) communications.
   First, this document surveys use cases using V2V, V2I, and V2X
   networking.  Second, it analyzes proposed protocols for IP-based
   vehicular networking and highlights the limitations and difficulties
   found on those protocols.  Third, it presents a problem exploration
   for key aspects in IP-based vehicular networking, such as IPv6
   Neighbor Discovery, Mobility Management, and Security & Privacy.  For
   each key aspect, this document discusses a problem statement to
   evaluate the gap between the state-of-the-art techniques and
   requirements in IP-based vehicular networking.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  V2V . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  V2I . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.3.  V2X . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Analysis for Existing Protocols . . . . . . . . . . . . . . .   7   8
     4.1.  Existing Protocols for Vehicular Networking . . . . . . .   8
       4.1.1.  IPv6 over 802.11-OCB  . . . . . . . . . . . . . . . .   8
       4.1.2.  IP Address Autoconfiguration  . . . . . . . . . . . .   8
       4.1.3.  Routing . . . . . . . . . . . . . . . . . . . . . . .   9
       4.1.4.  Mobility Management . . . . . . . . . . . . . . . . .   9
       4.1.5.  DNS Naming Service  . . . . . . . . . . . . . . . . .   9
       4.1.6.  Service Discovery . . . . . . . . . . . . . . . . . .   9
       4.1.7.  Security and Privacy  . . . . . . . . . . . . . . . .  10
     4.2.  General Problems  . . . . . . . . . . . . . . . . . . . .  10
       4.2.1.  Vehicular Network Architecture  . . . . . . . . . . .  11
       4.2.2.  Latency . . . . . . . . . . . . . . . . . . . . . . .  15  16
       4.2.3.  Security  . . . . . . . . . . . . . . . . . . . . . .  15  16
       4.2.4.  Pseudonym Handling  . . . . . . . . . . . . . . . . .  15  16
   5.  Problem Exploration . . . . . . . . . . . . . . . . . . . . .  16  17
     5.1.  Neighbor Discovery  . . . . . . . . . . . . . . . . . . .  16  17
       5.1.1.  Link Model  . . . . . . . . . . . . . . . . . . . . .  16  17
       5.1.2.  MAC Address Pseudonym . . . . . . . . . . . . . . . .  17  18
       5.1.3.  Prefix Dissemination/Exchange . . . . . . . . . . . .  17  18
       5.1.4.  Routing . . . . . . . . . . . . . . . . . . . . . . .  17  18
     5.2.  Mobility Management . . . . . . . . . . . . . . . . . . .  17  19
     5.3.  Security and Privacy  . . . . . . . . . . . . . . . . . .  18  20
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  19  20
   7.  Informative References  . . . . . . . . . . . . . . . . . . .  19  21
   Appendix A.  Relevant Topics to IPWAVE Working Group  . . . . . .  27  29
     A.1.  Vehicle Identity Management . . . . . . . . . . . . . . .  27  29
     A.2.  Multihop V2X  . . . . . . . . . . . . . . . . . . . . . .  27  29
     A.3.  Multicast . . . . . . . . . . . . . . . . . . . . . . . .  27  29
     A.4.  DNS Naming Services and Service Discovery . . . . . . . .  28  30
     A.5.  IPv6 over Cellular Networks . . . . . . . . . . . . . . .  28  30
       A.5.1.  Cellular V2X (C-V2X) Using 4G-LTE . . . . . . . . . .  28  30
       A.5.2.  Cellular V2X (C-V2X) Using 5G . . . . . . . . . . . .  29  31
   Appendix B.  Changes from draft-ietf-ipwave-vehicular-
                networking-06  . . . . . . . . . . . . . . . . . . .  29  31
   Appendix C.  Acknowledgments  . . . . . . . . . . . . . . . . . .  29  31
   Appendix D.  Contributors . . . . . . . . . . . . . . . . . . . .  29  32
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  31  34

1.  Introduction

   Vehicular networking studies have mainly focused on driving safety,
   driving efficiency, and entertainment in road networks.  The Federal
   Communications Commission (FCC) in the US allocated wireless channels
   for Dedicated Short-Range Communications (DSRC) [DSRC], service in
   the Intelligent Transportation Systems (ITS) Radio Service in the
   5.850 - 5.925 GHz band (5.9 GHz band).  DSRC-based wireless
   communications can support vehicle-to-vehicle (V2V), vehicle-to-
   infrastructure (V2I), and vehicle-to-everything (V2X) networking.
   Also, the European Union (EU) passed a decision to allocate radio
   spectrum for safety-related and non-safety-related applications of
   ITS with the frequency band of 5.875 - 5.905 GHz, which is called
   Commission Decision 2008/671/EC [EU-2008-671-EC].

   For direct inter-vehicular wireless connectivity, IEEE has amended
   WiFi standard 802.11 to enable driving safety services based on the
   DSRC in terms of standards for the Wireless Access in Vehicular
   Environments (WAVE) system.  L1 and L2 issues are addressed in IEEE
   802.11p [IEEE-802.11p] for the PHY and MAC of the DSRC, while IEEE
   1609.2 [WAVE-1609.2] covers security aspects, IEEE 1609.3
   [WAVE-1609.3] defines related services at network and transport
   layers, and IEEE 1609.4 [WAVE-1609.4] specifies the multi-channel
   operation.  Note that IEEE 802.11p has been published as IEEE 802.11
   Outside the Context of a Basic Service Set (OCB) called IEEE
   802.11-OCB [IEEE-802.11-OCB] in 2012.

   Along with these WAVE standards, IPv6 [RFC8200] and Mobile IP
   protocols (e.g., MIPv4 [RFC5944] and MIPv6 [RFC6275]) can be applied
   (or easily modified) to vehicular networks.  In Europe, ETSI has
   standardized a GeoNetworking (GN) protocol [ETSI-GeoNetworking] and a
   protocol adaptation sub-layer from GeoNetworking to IPv6
   [ETSI-GeoNetwork-IP].  Note that a GN protocol is useful to route an
   event or notification message to vehicles around a geographic
   position, such as an acciendent area in a roadway.  In addition, ISO
   has approved a standard specifying the IPv6 network protocols and
   services to be used for Communications Access for Land Mobiles (CALM)

   This document discusses problem statements and use cases related to
   IP-based vehicular networking for Intelligent Transportation Systems
   (ITS), which is denoted as IP Wireless Access in Vehicular
   Environments (IPWAVE).  First, it surveys the use cases for using
   V2V, V2I, and V2X networking in the ITS.  Second, for literature
   review, it analyzes proposed protocols for IP-based vehicular
   networking and highlights the limitations and difficulties found on
   those protocols.  Third, for problem statement, it presents a problem
   exploration with key aspects in IPWAVE, such as IPv6 Neighbor
   Discovery, Mobility Management, and Security & Privacy.  For each key
   aspect of the problem statement, it analyzes the gap between the
   state-of-the-art techniques and the requirements in IP-based
   vehicular networking.  It also discusses potential topics relevant to
   IPWAVE Working Group (WG), such as Vehicle Identities Management,
   Multihop V2X Communications, Multicast, DNS Naming Services, Service
   Discovery, and IPv6 over Cellular Networks.  Therefore, with the
   problem statement, this document will open a door to develop key
   protocols for IPWAVE that will be essential to IP-based vehicular

2.  Terminology

   This document uses the following definitions:

   o  WAVE: Acronym for "Wireless Access in Vehicular Environments"

   o  DMM: Acronym for "Distributed Mobility Management"

   o  Road-Side Unit (RSU): A node that has physical communication
      devices (e.g., DSRC, Visible Light Communication, 802.15.4, LTE-
      V2X, etc.) for wireless communications with vehicles and is also
      connected to the Internet as a router or switch for packet
      forwarding.  An RSU is typically deployed on the road
      infrastructure, either at an intersection or in a road segment,
      but may also be located in car parking area.

   o  On-Board Unit (OBU): A node that has a DSRC device for wireless
      communications with other OBUs and RSUs, and may be connected to
      in-vehicle devices or networks.  An OBU is mounted on a vehicle.
      It is assumed that a radio navigation receiver (e.g., Global
      Positioning System (GPS)) is included in a vehicle with an OBU for
      efficient navigation.

   o  Vehicle Detection Loop (or Loop Detector): An inductive device
      used for detecting vehicles passing or arriving at a certain
      point, for instance approaching a traffic light or in motorway
      traffic.  The relatively crude nature of the loop's structure
      means that only metal masses above a certain size are capable of
      triggering the detection.

   o  Mobility Anchor (MA): A node that maintains IP addresses and
      mobility information of vehicles in a road network to support the
      address autoconfiguration and mobility management of them.  It has
      end-to-end connections with RSUs under its control.  It maintains
      a DAD table having the IP addresses of the vehicles moving within
      the communication coverage of its RSUs.

   o  Vehicular Cloud: A cloud infrastructure for vehicular networks,
      having compute nodes, storage nodes, and network nodes.

   o  Traffic Control Center (TCC): A node that maintains road
      infrastructure information (e.g., RSUs, traffic signals, and loop
      detectors), vehicular traffic statistics (e.g., average vehicle
      speed and vehicle inter-arrival time per road segment), and
      vehicle information (e.g., a vehicle's identifier, position,
      direction, speed, and trajectory as a navigation path).  TCC is
      included in a vehicular cloud for vehicular networks.

3.  Use Cases

   This section provides use cases of V2V, V2I, and V2X networking.  The
   use cases of the V2X networking exclude the ones of the V2V and V2I
   networking, but include Vehicle-to-Pedestrian (V2P) and Vehicle-to-
   Device (V2D).

3.1.  V2V

   The use cases of V2V networking discussed in this section include

   o  Context-aware navigation for driving safety and collision

   o  Cooperative adaptive cruise control in an urban roadway;

   o  Platooning in a highway;

   o  Cooperative environment sensing.

   These four techniques will be important elements for self-driving

   Context-Aware Safety Driving (CASD) navigator [CASD] can help drivers
   to drive safely by letting the drivers recognize dangerous obstacles
   and situations.  That is, CASD navigator displays obstables or
   neighboring vehicles relevant to possible collisions in real-time
   through V2V networking.  CASD provides vehicles with a class-based
   automatic safety action plan, which considers three situations, such
   as the Line-of-Sight unsafe, Non-Line-of-Sight unsafe and safe
   situations.  This action plan can be performed among vehicles through
   V2V networking.

   Cooperative Adaptive Cruise Control (CACC) [CA-Cruise-Control] helps
   vehicles to adapt their speed autonomously through V2V communication
   among vehicles according to the mobility of their predecessor and
   successor vehicles in an urban roadway or a highway.  CACC can help
   adjacent vehicles to efficiently adjust their speed in a cascade way
   through V2V networking.

   Platooning [Truck-Platooning] allows a series of vehicles (e.g.,
   trucks) to move together with a very short inter-distance.  Trucks
   can use V2V communication in addition to forward sensors in order to
   maintain constant clearance between two consecutive vehicles at very
   short gaps (from 3 meters to 10 meters).  This platooning can
   maximize the throughput of vehicular traffic in a highway and reduce
   the gas consumption because the leading vehicle can help the
   following vehicles to experience less air resistance.

   Cooperative-environment-sensing use cases suggest that vehicles can
   share environmental information from various vehicle-mounted sensors,
   such as radars, LiDARs and cameras with other vehicles and
   pedestrians.  [Automotive-Sensing] introduces a millimeter-wave
   vehicular communication for massive automotive sensing.  Data
   generated by those sensors can be substantially large, and these data
   shall be routed to different destinations.  In addition, from the
   perspective of driverless vehicles, it is expected that driverless
   vehicles can be mixed with driver-operated vehicles.  Through
   cooperative environment sensing, driver-operated vehicles can use
   environmental information sensed by driverless vehicles for better
   interaction with the context.

3.2.  V2I

   The use cases of V2I networking discussed in this section include

   o  Navigation service;

   o  Energy-efficient speed recommendation service;

   o  Accident notification service.

   A navigation service, such as the Self-Adaptive Interactive
   Navigation Tool (called SAINT) [SAINT], using V2I networking
   interacts with TCC for the large-scale/long-range road traffic
   optimization and can guide individual vehicles for appropriate
   navigation paths in real time.  The enhanced SAINT (called SAINT+)
   [SAINTplus] can give the fast moving paths for emergency vehicles
   (e.g., ambulance and fire engine) toward accident spots while
   providing other vehicles with efficient detour paths.

   A TCC can recommend an energy-efficient speed to a vehicle driving in
   different traffic environments.  [Fuel-Efficient] studies fuel-
   efficient route and speed plans for platooned trucks.

   The emergency communication between accident vehicles (or emergency
   vehicles) and TCC can be performed via either RSU or 4G-LTE networks.
   The First Responder Network Authority (FirstNet) [FirstNet] is
   provided by the US government to establish, operate, and maintain an
   interoperable public safety broadband network for safety and security
   network services, such as emergency calls.  The construction of the
   nationwide FirstNet network requires each state in the US to have a
   Radio Access Network (RAN) that will connect to FirstNet's network
   core.  The current RAN is mainly constructed by 4G-LTE for the
   communication between a vehicle and an infrastructure node (i.e.,
   V2I) [FirstNet-Report], but it is expected that DSRC-based vehicular
   networks [DSRC] will be available for V2I and V2V in near future.

3.3.  V2X

   The use case of V2X networking discussed in this section is
   pedestrian protection service.

   A pedestrian protection service, such as Safety-Aware Navigation
   Application (called SANA) [SANA], using V2I2P networking can reduce
   the collision of a vehicle and a pedestrian carrying a smartphone
   equipped with the access technology with an RSU (e.g., WiFi).
   Vehicles and pedestrians can also communicate with each other via an
   RSU that delivers scheduling information for wireless communication
   in order to save the smartphones' battery through sleeping mode.

   For Vehicle-to-Pedestrian (V2P), a vehicle and a pedestrian's
   smartphone can directly communicate with each other via V2X without
   the relaying of an RSU as in a V2V scenario such that the
   pedestrian's smartphone is regarded as a vehicle with a wireless
   media interface to be able to communicate with another vehicle.  In
   Vehicle-to-Device (V2D), a device can be a mobile node such as
   bicycle and motorcycle, and can communicate directly with a vehicle
   for collision avoidance.

4.  Analysis for Existing Protocols

4.1.  Existing Protocols for Vehicular Networking

   We describe some currently existing protocols and proposed solutions
   with respect to the following aspects that are relevant and essential
   for vehicular networking:

   o  IPv6 over 802.11-OCB;

   o  IP address autoconfiguration;

   o  Routing;

   o  Mobility management;

   o  DNS naming service;

   o  Service discovery;

   o  Security and privacy.

4.1.1.  IPv6 over 802.11-OCB

   For IPv6 packets transporting over IEEE 802.11-OCB,
   [IPv6-over-802.11-OCB] specifies several details, such as Maximum
   Transmission Unit (MTU), frame format, link-local address, address
   mapping for unicast and multicast, stateless autoconfiguration, and
   subnet structure.  Especially, an Ethernet Adaptation (EA) layer is
   in charge of transforming some parameters between IEEE 802.11 MAC
   layer and IPv6 network layer, which is located between IEEE
   802.11-OCB's logical link control layer and IPv6 network layer.

4.1.2.  IP Address Autoconfiguration

   For IP address autoconfiguration, Fazio et al. proposed a vehicular
   address configuration (VAC) scheme using DHCP where elected leader-
   vehicles provide unique identifiers for IP address configurations in
   vehicles [Address-Autoconf].  Kato et al. proposed an IPv6 address
   assignment scheme using lane and position information
   [Address-Assignment].  Baldessari et al. proposed an IPv6 scalable
   address autoconfiguration scheme called GeoSAC for vehicular networks
   [GeoSAC].  Wetterwald et al. conducted for heterogeneous vehicular
   networks (i.e., employing multiple access technologies) a
   comprehensive study of the cross-layer identities management, which
   constitutes a fundamental element of the ITS architecture

4.1.3.  Routing

   For routing, Tsukada et al. presented a work that aims at combining
   IPv6 networking and a Car-to-Car Network routing protocol (called
   C2CNet) proposed by the Car2Car Communication Consortium (C2C-CC),
   which is an architecture using a geographic routing protocol
   [VANET-Geo-Routing].  Abrougui et al. presented a gateway discovery
   scheme for VANET, called Location-Aided Gateway Advertisement and
   Discovery (LAGAD) mechanism [LAGAD].

4.1.4.  Mobility Management

   For mobility management, Chen et al. tackled the issue of network
   fragmentation in VANET environments [IP-Passing-Protocol] by
   proposing a protocol that can postpone the time to release IP
   addresses to the DHCP server and select a faster way to get the
   vehicle's new IP address, when the vehicle density is low or the
   speeds of vehicles are highly variable.  Nguyen et al. proposed a
   hybrid centralized-distributed mobility management called H-DMM to
   support highly mobile vehicles [H-DMM].  [NEMO-LMS] proposed an
   architecture to enable IP mobility for moving networks using a
   network-based mobility scheme based on PMIPv6.  Chen et al. proposed
   a network mobility protocol to reduce handoff delay and maintain
   Internet connectivity to moving vehicles in a highway [NEMO-VANET].
   Lee et al. proposed P-NEMO, which is a PMIPv6-based IP mobility
   management scheme to maintain the Internet connectivity at the
   vehicle as a mobile network, and provides a make-before-break
   mechanism when vehicles switch to a new access network
   [PMIP-NEMO-Analysis].  Peng et al. proposed a novel mobility
   management scheme for integration of VANET and fixed IP networks
   [VNET-MM].  Nguyen et al. extended their previous works on a
   vehicular adapted DMM considering a Software-Defined Networking (SDN)
   architecture [SDN-DMM].

4.1.5.  DNS Naming Service

   For DNS naming service, Multicast DNS (mDNS) [RFC6762] allows devices
   in one-hop communication range to resolve each other's DNS name into
   the corresponding IP address in multicast.  DNS Name
   Autoconfiguration (DNSNA) [ID-DNSNA] proposes a DNS naming service
   for Internet-of-Things (IoT) devices in a large-scale network.

4.1.6.  Service Discovery

   To discover instances of a demanded service in vehicular networks,
   DNS-based Service Discovery (DNS-SD) [RFC6763] with either DNSNA
   [ID-DNSNA] or mDNS [RFC6762] provides vehicles with service discovery
   by using standard DNS queries.  Vehicular ND [ID-Vehicular-ND]
   proposes an extension of IPv6 ND for the prefix and service
   discovery. discovery
   with new ND options [ID-VND-Discovery].  Note that a DNS query for
   service discovery is unicasted in DNSNA, but it is multicasted in
   both mDNS and Vehicular ND.

4.1.7.  Security and Privacy

   For security and privacy, Fernandez et al. proposed a secure
   vehicular IPv6 communication scheme using Internet Key Exchange
   version 2 (IKEv2) and Internet Protocol Security (IPsec)
   [Securing-VCOMM].  Moustafa et al. proposed a security scheme
   providing authentication, authorization, and accounting (AAA)
   services in vehicular networks [VNET-AAA].


4.2.  General Problems

   This section describes a possible vehicular network architecture for
   V2V, V2I, and V2X communications.  Then it analyzes the limitations
   of the current protocols for vehicular networking.

                     Traffic Control Center in Vehicular Cloud
                   *                                           *         +-------+
                  * Vehicular Cloud *<------>|  TCC             +----------------+              *
                 *              | Mobility Anchor|               *
                 *              +----------------+               *
                  *                      ^                      *
                   *                     |                     *         +_______+
                    ^               ^                        ^
                    |               |                        |
+------------------ |  -------------|-------------+ +------------------+
|                   v               v             | |        v         |
|           +--------+  Ethernet   +--------+     | |    +--------+    |
|           |  RSU1  |<----------->|  RSU2  |<---------->|  RSU3  |
                      +________+             +________+    |
|           +--------+             +--------+     | |    +--------+    |
|           ^        ^                  ^         | |        ^         |
|           :        :                  :         | |        :         |
|       V2I :        : V2I          V2I :         | |    V2I :         |
|           v        v                  v         | |        v         |
|   +--------+      +--------+      +--------+
              |Vehicle1|==>   |Vehicle2|==>   |Vehicle3|==>    | |    +--------+    |
|   |Vehicle1|===>  |Vehicle2|===>  |Vehicle3|===>| |    |Vehicle4|===>|
|   |        |<....>|        |<....>|        |
              +________+    | |    |        |    |
|   +--------+ V2V  +________+  +--------+ V2V  +________+  +--------+    | |    +--------+    |
|                                                 | |                  |
+-------------------------------------------------+ +------------------+
                      Subnet1                              Subnet2

   <----> Wired Link   <....> Wireless Link   ==>   ===> Moving Direction

   Figure 1: A Vehicular Network Architecture for V2I and V2V Networking

4.2.  General Problems

   This section describes a possible vehicular network architecture for
   V2V, V2I, and V2X communications.  Then it analyzes the limitations
   of the current protocols for vehicular networking.

4.2.1.  Vehicular Network Architecture

   Figure 1 shows a possible architecture for V2I and V2V networking in
   a road network.  It is assumed that RSUs as routers and vehicles with
   OBU have wireless media interfaces (e.g., IEEE 802.11-OCB, LTE Uu and
   Device-to-Device (D2D) (also known as PC5 [TS-23.285-3GPP]),
   Bluetooth, and Light Fidelity (Li-Fi)) for V2I and V2V communication.
   Also, it is assumed that such the wireless media interfaces are
   autoconfigured with a global IPv6 prefix (e.g., 2001:DB8:1:1::/64) to
   support both V2V and V2I networking.  The two  Three RSUs (RSU1 (RSU1, RSU2, and RSU2)
   RSU3) are deployed in the road network and are connected to a
   Vehicular Cloud through the Internet.  TCC  A Traffic Control Center (TCC)
   is connected to the Vehicular Cloud
   and for the two vehicles (Vehicle1 and management of RSUs and
   vehicles in the road network.  A Mobility Anchor (MA) is located in
   the TCC as its key component for the mobility management of vehicles.
   Two vehicles (Vehicle1 and Vehicle2) are wirelessly connected to
   RSU1, and the last one vehicle (Vehicle3) is wirelessly connected to RSU2.
   The wireless networks of RSU1 and RSU2 belong to a multi-link subnet
   (denoted as Subnet1) with the same network prefix.  Thus, these three
   vehicles are within the same subnet.  On the other hand, another
   vehicle (Vehicle4) is wireless connected to RSU4, belonging to
   another subnet (denoted as Subnet2).  That is, the first three
   vehicles (i.e., Vehicle1, Vehicle2, and Vehicle3) and the last
   vehicle (i.e., Vehicle4) are located in the two different subnets.
   Vehicle1 can communicate with Vehicle2 via V2V communication, and
   Vehicle2 can communicate with Vehicle3 via V2V communication.
   Vehicle1 communication because
   they are within the same subnet along their IPv6 addresses, which are
   based on the same prefix.  On the other hand, Vehicle3 can
   communicate with Vehicle3 Vehicle4 via RSU1 and RSU2 and RSU3 employing V2I (i.e.,
   V2I2V) communication. communication because they are within the two different
   subnets along with their IPv6 addresses, which are based on the two
   different prefixes.

   In vehicular networks, unidirectional links exist and must be
   considered for wireless communications.  Also, in the vehicular
   networks, control plane must be separated from data plane for
   efficient mobility management and data forwarding using Software-
   Defined Networking (SDN) [SDN-DMM].  ID/Pseudonym change for privacy
   requires a lightweight DAD.  IP tunneling over the wireless link
   should be avoided for performance efficiency.  The mobility
   information of a mobile (e.g., vehicle-mounted) device through a GPS
   receiver in its vehicle, such as trajectory, position, speed, and
   direction, can be used by the mobile device and infrastructure nodes
   (e.g., TCC and RSU) for the accommodation of mobility-aware proactive
   protocols.  Vehicles can use the TCC as their Home Network having a
   home agent for mobility management as in MIPv6 [RFC6275] and Proxy
   Mobile IPv6 (PMIPv6) [RFC5213], so the TCC maintains the mobility
   information of vehicles for location management.

   Cespedes et al. proposed a vehicular IP in WAVE called VIP-WAVE for
   I2V and V2I networking [VIP-WAVE].  The standard WAVE does not
   support both seamless communications for Internet services and multi-
   hop communications between a vehicle and an infrastructure node
   (e.g., RSU), either.  To overcome these limitations of the standard
   WAVE, VIP-WAVE enhances the standard WAVE by the following three
   schemes: (i) an efficient mechanism for the IPv6 address assignment
   and DAD, (ii) on-demand IP mobility based on PMIPv6 [RFC5213], and
   (iii) one-hop and two-hop communications for I2V and V2I networking.

   Baccelli et al. provided an analysis of the operation of IPv6 as it
   has been described by the IEEE WAVE standards 1609 [IPv6-WAVE].  This
   analysis confirms that the use of the standard IPv6 protocol stack in
   WAVE is not sufficient.  It recommends that the IPv6 addressing
   assignment should follow considerations for ad-hoc link models,
   defined in [RFC5889] for nodes' mobility and link variability.

   Petrescu et al. proposed the joint IP networking and radio
   architecture for V2V and V2I communication in [Joint-IP-Networking].
   The proposed architecture considers an IP topology in a similar way
   as a radio link topology, in the sense that an IP subnet would
   correspond to the range of 1-hop vehicular communication.  This
   architecture defines three types of vehicles: Leaf Vehicle, Range
   Extending Vehicle, and Internet Vehicle.

                           (*)<........>(*)  +----->| Vehicular Cloud|
          2001:DB8:1:1::/64 |            |   |      +----------------+
   +------------------------------+  +---------------------------------+
   |                        v     |  |   v   v                         |
   | .-------. .------. .-------. |  | .-------. .------. .-------.    |
   | | Host1 | |RDNSS1| |Router1| |  | |Router3| |RDNSS2| | Host3 |    |
   | ._______. .______. ._______. |  | ._______. .______. ._______.    |
   |     ^        ^         ^     |  |     ^         ^        ^        |
   |     |        |         |     |  |     |         |        |        |
   |     v        v         v     |  |     v         v        v        |
   | ---------------------------- |  | ------------------------------- |
   | 2001:DB8:10:1::/64 ^         |  |     ^ 2001:DB8:20:1::/64        |
   |                    |         |  |     |                           |
   |                    v         |  |     v                           |
   | .-------.      .-------.     |  | .-------. .-------.   .-------. |
   | | Host2 |      |Router2|     |  | |Router4| |Server1|...|ServerN| |
   | ._______.      ._______.     |  | ._______. ._______.   ._______. |
   |     ^              ^         |  |     ^         ^           ^     |
   |     |              |         |  |     |         |           |     |
   |     v              v         |  |     v         v           v     |
   | ---------------------------- |  | ------------------------------- |
   |  2001:DB8:10:2::/64          |  |       2001:DB8:20:2::/64        |
   +______________________________+  +_________________________________+
      Vehicle1 (Moving Network1)            RSU1 (Fixed Network1)

      <----> Wired Link   <....> Wireless Link   (*) Antenna

     Figure 2: Internetworking between Vehicle Network and RSU Network  V2I-based Internetworking

   This section discusses the internetworking between a vehicle's moving
   network and an RSU's fixed network via V2I communication.

   As shown in Figure 2, the vehicle's moving network and the RSU's
   fixed network are self-contained networks having multiple subnets and
   having an edge router for the communication with another vehicle or
   RSU.  The method of prefix assignment for each subnet inside the
   vehicle's mobile network and the RSU's fixed network is out of scope
   for this document.  Internetworking between two internal networks via
   V2I communication requires an exchange of network prefix and other
   parameters through a prefix discovery mechanism, such as ND-based
   prefix discovery [ID-Vehicular-ND]. [ID-VND-Discovery].  For the ND-based prefix
   discovery, network prefixs and parameters should be registered into a
   vehicle's router and an RSU router with an external network interface
   in advance.

   The network parameter discovery collects networking information for
   an IP communication between a vehicle and an RSU or between two
   neighboring vehicles, such as link layer, MAC layer, and IP layer
   information.  The link layer information includes wireless link layer
   parameters, such as wireless media (e.g., IEEE 802.11-OCB, LTE Uu and
   D2D, Bluetooth, and LiFi) and a transmission power level.  Note that
   LiFi is a technology for light-based wireless communication between
   devices in order to transmit both data and position.  The MAC layer
   information includes the MAC address of an external network interface
   for the internetworking with another vehicle or RSU.  The IP layer
   information includes the IP address and prefix of an external network
   interface for the internetworking with another vehicle or RSU.

   Once the network parameter discovery and prefix exchange operations
   have been performed, packets can be transmitted between the vehicle's
   moving network and the RSU's fixed network.  DNS services should be
   supported to enable name resolution for hosts or servers residing
   either in the vehicle's moving network or the RSU's fixed network.
   It is assumed that the DNS names of in-vehicle devices and their
   service names are registered into a DNS server (i.e., recursive DNS
   server called RDNSS) in a vehicle or an RSU, as shown in Figure 2.
   For service discovery, those DNS names and service names can be
   advertised to neighboring vehicles through either DNS-based service
   discovery mechanisms [RFC6762][RFC6763][ID-DNSNA] and ND-based
   service discovery [ID-Vehicular-ND]. [ID-Vehicular-ND][ID-VND-Discovery].  For the ND-based ND-
   based service discovery, service names should be registered into a
   vehicle's router and an RSU router with an external network interface
   in advance.  Refer to Section 4.1.5 and Section 4.1.6 for detailed
   information.  For these DNS services, an RDNSS within each internal
   network of a vehicle or RSU can be used for the hosts or servers.

   Figure 2 shows internetworking between the vehicle's moving network
   and the RSU's fixed network.  There exists an internal network
   (Moving Network1) inside Vehicle1.  Vehicle1 has the DNS Server
   (RDNSS1), the two hosts (Host1 and Host2), and the two routers
   (Router1 and Router2).  There exists another internal network (Fixed
   Network1) inside RSU1.  RSU1 has the DNS Server (RDNSS2), one host
   (Host3), the two routers (Router3 and Router4), and the collection of
   servers (Server1 to ServerN) for various services in the road
   networks, such as the emergency notification and navigation.
   Vehicle1's Router1 (called mobile router) and RSU1's Router3 (called
   fixed router) use 2001:DB8:1:1::/64 for an external link (e.g., DSRC)
   for I2V networking.

          2001:DB8:1:1::/64 |              |
   +------------------------------+  +---------------------------------+
   |                        v     |  |     v                           |
   | .-------. .------. .-------. |  | .-------. .------. .-------.    |
   | | Host1 | |RDNSS1| |Router1| |  | |Router5| |RDNSS3| | Host4 |    |
   | ._______. .______. ._______. |  | ._______. .______. ._______.    |
   |     ^        ^         ^     |  |     ^         ^        ^        |
   |     |        |         |     |  |     |         |        |        |
   |     v        v         v     |  |     v         v        v        |
   | ---------------------------- |  | ------------------------------- |
   | 2001:DB8:10:1::/64 ^         |  |     ^ 2001:DB8:30:1::/64        |
   |                    |         |  |     |                           |
   |                    v         |  |     v                           |
   | .-------.      .-------.     |  | .-------.      .-------.        |
   | | Host2 |      |Router2|     |  | |Router6|      | Host5 |        |
   | ._______.      ._______.     |  | ._______.      ._______.        |
   |     ^              ^         |  |     ^              ^            |
   |     |              |         |  |     |              |            |
   |     v              v         |  |     v              v            |
   | ---------------------------- |  | ------------------------------- |
   |  2001:DB8:10:2::/64          |  |       2001:DB8:30:2::/64        |
   +______________________________+  +_________________________________+
      Vehicle1 (Moving Network1)        Vehicle2 (Moving Network2)

      <----> Wired Link   <....> Wireless Link   (*) Antenna

          Figure 3: Internetworking between Two Vehicle Networks  V2V-based Internetworking

   This section discusses the internetworking between the moving
   networks of two neighboring vehicles via V2V communication.

   Figure 3 shows internetworking between the moving networks of two
   neighboring vehicles.  There exists an internal network (Moving
   Network1) inside Vehicle1.  Vehicle1 has the DNS Server (RDNSS1), the
   two hosts (Host1 and Host2), and the two routers (Router1 and
   Router2).  There exists another internal network (Moving Network2)
   inside Vehicle2.  Vehicle2 has the DNS Server (RDNSS3), the two hosts
   (Host4 and Host5), and the two routers (Router5 and Router6).

   Vehicle1's Router1 (called mobile router) and Vehicle2's Router5
   (called mobile router) use 2001:DB8:1:1::/64 for an external link
   (e.g., DSRC) for V2V networking.

   The differences between IPWAVE (including Vehicular Ad Hoc Networks
   (VANET)) and Mobile Ad Hoc Networks (MANET) are as follows:

   o  IPWAVE is not power-constrained operation;

   o  Traffic can be sourced or sinked outside of IPWAVE;

   o  IPWAVE shall support both distributed and centralized operations;

   o  No "sleep" period operation is required for energy saving.

4.2.2.  Latency

   The communication delay (i.e., latency) between two vehicular nodes
   (vehicle and RSU) should be bounded to a certain threshold.  For IP-
   based safety applications (e.g., context-aware navigation, adaptive
   cruise control, and platooning) in vehicular network, this bounded
   data delivery is critical.  The real implementations for such
   applications are not available, so the feasibility of IP-based safety
   applications is not tested yet.

4.2.3.  Security

   Strong security measures shall protect vehicles roaming in road
   networks from the attacks of malicious nodes, which are controlled by
   hackers.  For safety applications, the cooperation among vehicles is
   assumed.  Malicious nodes may disseminate wrong driving information
   (e.g., location, speed, and direction) to make driving be unsafe.
   Sybil attack, which tries to illude a vehicle with multiple false
   identities, disturbs a vehicle in taking a safe maneuver.
   Applications on IP-based vehicular networking, which are resilient to
   such a sybil attack, are not developed and tested yet.

4.2.4.  Pseudonym Handling

   For the protection of drivers' privacy, pseudonym for a vehicle's
   network interface should be used, with the help of which the
   interface's identifier can be changed periodically.  Such a pseudonym
   affects an IPv6 address based on the network interface's identifier,
   and a transport-layer (e.g., TCP) session with an IPv6 address pair.
   The pseudonym handling is not implemented and tested yet for
   applications on IP-based vehicular networking.

5.  Problem Exploration

   This section discusses key topics for IPWAVE WG, such as neighbor
   discovery, mobility management, and security & privacy.

5.1.  Neighbor Discovery

   Neighbor Discovery (ND) [RFC4861] is a core part of the IPv6 protocol
   suite.  This section discusses the need for modifying ND for use with
   vehicular networking (e.g., V2V, V2I, and V2X).  The vehicles are
   moving fast within the communication coverage of a vehicular node
   (e.g., vehicle and RSU).  The external wireless link between two
   vehicular nodes can be used for vehicular networking, as shown in
   Figure 2 and Figure 3.

   ND time-related parameters such as router lifetime and Neighbor
   Advertisement (NA) interval should be adjusted for high-speed
   vehicles and vehicle density.  As vehicles move faster, the NA
   interval should decrease for the NA messages to reach the neighboring
   vehicles promptly.  Also, as vehicle density is higher, the NA
   interval should increase for the NA messages to reduce collision
   probability with other NA messages.

5.1.1.  Link Model

   IPv6 protocols work under certain assumptions for the link model that
   do not necessarily hold in WAVE [IPv6-WAVE]. a vehicular wireless link [VIP-WAVE].  For
   instance, some IPv6 protocols assume symmetry in the connectivity
   among neighboring interfaces.  However, interference and different
   levels of transmission power may cause unidirectional links to appear
   in vehicular wireless links.  As a WAVE result, a new vehicular link model. model
   is required for the vehicular wireless link.

   There is a relationship between a link and prefix, besides the
   different scopes that are expected from the link-local and global
   types of IPv6 addresses.  In an IPv6 link, it is assumed that all
   interfaces which are configured with the same subnet prefix and with
   on-link bit set can communicate with each other on an IP link or
   extended IP links via ND proxy.  Note that a subnet prefix can be
   used by spanning multiple links as a multi-link subnet [RFC6775].
   Also, note that IPv6 Stateless Address Autoconfiguration can be
   performed in the multiple links where each of them is not assigned
   with a unique subnet prefix, that is, all of them are configured with
   the same subnet prefix [RFC4861][RFC4862].  A WAVE vehicular link model
   needs to consider a multi-hop VANET over a multi-link subnet.  Such a
   VANET is usually a multi-link subnet consisting of multiple vehicles
   interconnected by wireless communication range.  Such a subnet has a
   highly dynamic topology over time due to node mobility.

   Thus, IPv6 ND should be extended into a Vehicular Neighbor Discovey
   (VND) [ID-Vehicular-ND] to support the concept of an IPv6 link
   corresponding to an IPv6 prefix even in a multi-link subnet
   consisting of multiple vehicles and RSUs that are interconnected with
   wireless communication range in IP-based vehicular networks.

5.1.2.  MAC Address Pseudonym

   In the ETSI standards, for the sake of security and privacy, an ITS
   station (e.g., vehicle) can use pseudonyms for its network interface
   identities (e.g., MAC address) and the corresponding IPv6 addresses
   [Identity-Management].  Whenever the network interface identifier
   changes, the IPv6 address based on the network interface identifier
   should be updated.  For the continuity of an end-to-end (E2E)
   transport-layer (e.g., TCP, UDP, and SCTP) session, with a mobility
   management scheme (e.g., MIPv6 and PMIPv6), the new IP
   addresses of address for
   the transport-layer session should be notified to both
   the an appropriate end points
   point, and the packets of the session should be forwarded to their
   destinations with the changed network interface identifier and IPv6

5.1.3.  Prefix Dissemination/Exchange

   A vehicle and an RSU can have their internal network, as shown in
   Figure 2 and Figure 3.  In this case, nodes in within the internal
   networks of two vehicular nodes (e.g., vehicle and RSU) want to
   communicate with each other.  For this communication on the wireless
   link, the network prefix dissemination or exchange is required.  It
   is assumed that a vehicular node has an external network interface
   and its internal network.  The standard legacy IPv6 ND [RFC4861] needs to be
   extended to a vehicular ND (VND) [ID-Vehicular-ND] for the
   communication between the internal-network nodes (e.g., an in-vehicle
   device in a vehicle and a server in an RSU) of vehicular nodes by
   letting each of them know the other side's prefix with a new ND
   option [ID-Vehicular-ND]. [ID-VND-Discovery].  Thus, this ND extension for routing
   functionality can reduce control traffic for routing in vehicular
   networks without an additional vehicular ad hoc routing protocol

5.1.4.  Routing

   For Neighbor Discovery multihop V2V communications in a multi-link subnet (as a
   connected VANET), a vehicular networks (called vehicular ND),
   Ad Hoc ad hoc routing is protocol (e.g.,
   geographic routing) may be required for either to support both unicast or and
   multicast in the links in a connected VANET of the subnet with the same IPv6 prefix [GeoSAC].  Also,
   [VANET-Geo-Routing].  Instead of the vehicular ad hoc routing
   protocol, Vehicular ND along with a prefix discovery option can be
   used to let vehicles exchange their prefixes in a multihop fashion

   [ID-Vehicular-ND][ID-VND-Discovery].  With the exchanged prefixes,
   they can compute their routing table (or IPv6 ND's neighbor cache)
   for the multi-link subnet with a distance-vector algorithm
   [Intro-to-Algorithms].  Also, an efficient, rapid DAD should be
   supported to prevent or reduce IPv6 address conflicts in a multi-link the multi-
   link subnet for both V2V and V2I by using a DAD optimization [RFC6775]. [ID-Vehicular-ND][RFC6775] or
   an IPv6 geographic-routing-based address autoconfiguration [GeoSAC].

5.2.  Mobility Management

   The seamless connectivity and timely data exchange between two end
   points requires an efficient mobility management including location
   management and handover.  Most of vehicles are equipped with a GPS
   receiver as part of a dedicated navigation system or a corresponding
   smartphone App.  In the case where the provided location information
   is precise enough, well-known temporary degradations in precision may
   occur due to system configuration or the adverse local environment.
   This precision is improved thanks to assistance by the RSUs or a
   cellular system with this navigation system.  With this GPS
   navigator, an efficient mobility management is possible by vehicles
   periodically reporting their current position and trajectory (i.e.,
   navigation path) to RSUs and a Mobility Anchor (MA) in TCC.  TCC  The RSUs
   and MA can predict the future positions of the vehicles with their
   mobility information (i.e., the current position, speed, direction,
   and trajectory) for location management. the efficient mobility management (e.g.,
   proactive handover).  For a better proactive handover, link-layer
   parameters, such as the signal strength of a link-layer frame (e.g.,
   Received Channel Power Indicator (RCPI) [VIP-WAVE]), can be used to
   determine the moment of a handover between RSUs along with mobility
   information [ID-Vehicular-ND].

   With the prediction of the vehicle mobility, TCC MA can support RSUs to
   perform DAD, data packet routing, horizontal handover (i.e., handover
   in wireless links using a homogeneous radio technology), and vertical
   handover (i.e., handover in wireless links using heterogeneous radio
   technologies) in a proactive manner.  When it is assigned  Even though a new IPv6
   address vehicle moves
   into the wireless link under another RSU belonging to a different
   subnet, a vehicle the RSU can skip proactively perform the DAD
   operation, for the sake of the
   vehicle, reducing IPv6 control traffic overhead. overhead in the wireless link

   Therefore, with a proactive handover and a multihop DAD in vehicular
   networks [ID-Vehicular-ND], RSUs can efficiently forward data packets
   from the wired network (or the wireless network) to a moving
   destination vehicle along its trajectory.  RSUs can smoothly perform
   handover for trajectory along with the sake of MA.  Thus, a
   moving vehicle can communicate with its corresponding vehicle in the
   vehicular network or a host/server in the Internet along its

5.3.  Security and Privacy

   Security and privacy are paramount in the V2I, V2V, and V2X
   networking in vehicular networks.  Only authorized vehicles should be
   allowed to use vehicular networking.  Also, in-vehicle devices and
   mobile devices in a vehicle need to communicate with other in-vehicle
   devices and mobile devices in another vehicle, and other servers in
   an RSU in a secure way.

   A Vehicle Identification Number (VIN) and a user certificate along
   with in-vehicle device's identifier generation can be used to
   efficiently authenticate a vehicle or a user through a road
   infrastructure node (e.g., RSU) connected to an authentication server
   in TCC.  Also, Transport Layer Security (TLS) certificates can be
   used for secure E2E vehicle communications.

   For secure V2I communication, a secure channel between a mobile
   router in a vehicle and a fixed router in an RSU should be
   established, as shown in Figure 2.  Also, for secure V2V
   communication, a secure channel between a mobile router in a vehicle
   and a mobile router in another vehicle should be established, as
   shown in Figure 3.

   To prevent an adversary from tracking a vehicle with its MAC address
   or IPv6 address, MAC address pseudonym should be provided to the
   vehicle; that is, each vehicle should periodically update its MAC
   address and the corresponding IPv6 address as suggested in
   [RFC4086][RFC4941].  Such an update of the MAC and IPv6 addresses
   should not interrupt the E2E communications between two vehicular
   nodes (e.g., vehicle and RSU) in terms of transport layer for a long-
   living higher-layer session.  However, if this pseudonym is performed
   without strong E2E confidentiality, there will be no privacy benefit
   from changing MAC and IP addresses, because an adversary can see the
   change of the MAC and IP addresses and track the vehicle with those

6.  Security Considerations

   This document discussed security and privacy for IP-based vehicular

   The security and privacy for key components in IP-based vehicular
   networking, such as neighbor discovery and mobility management, need
   to be analyzed in depth.

7.  Informative References

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              Fazio, M., Palazzi, C., Das, S., and M. Gerla, "Automatic
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              progress), July 2017.

              Camara, D., Bonnet, C., Nikaein, N., and M. Wetterwald,
              "Multicast and Virtual Road Side Units for Multi
              Technology Alert Messages Dissemination", IEEE 8th
              International Conference on Mobile Ad-Hoc and Sensor
              Systems, October 2011.

              Soto, I., Bernardos, C., Calderon, M., Banchs, A., and A.
              Azcorra, "NEMO-Enabled Localized Mobility Support for
              Internet Access in Automotive Scenarios",
              IEEE Communications Magazine, May 2009.

              Chen, Y., Hsu, C., and C. Cheng, "Network Mobility
              Protocol for Vehicular Ad Hoc Networks",
              Wiley International Journal of Communication Systems,
              November 2014.

              Lee, J., Ernst, T., and N. Chilamkurti, "Performance
              Analysis of PMIPv6-Based Network Mobility for Intelligent
              Transportation Systems", IEEE Transactions on Vehicular
              Technology, January 2012.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", RFC 4086, June

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP Version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, September 2007.

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for Stateless Address Autoconfiguration in
              IPv6", RFC 4941, September 2007.

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
              RFC 5213, August 2008.

   [RFC5889]  Baccelli, E. and M. Townsley, "IP Addressing Model in Ad
              Hoc Networks", RFC 5889, September 2010.

   [RFC5944]  Perkins, C., Ed., "IP Mobility Support in IPv4, Revised",
              RFC 5944, November 2010.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, July 2011.

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              February 2013.

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, February 2013.

   [RFC6775]  Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
              "Neighbor Discovery Optimization for IPv6 over Low-Power
              Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
              November 2012.

   [RFC7333]  Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for Distributed Mobility Management",
              RFC 7333, August 2014.

   [RFC7429]  Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ.
              Bernardos, "Distributed Mobility Management: Current
              Practices and Gap Analysis", RFC 7429, January 2015.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 8200, July 2017.

   [SAINT]    Jeong, J., Jeong, H., Lee, E., Oh, T., and D. Du, "SAINT:
              Self-Adaptive Interactive Navigation Tool for Cloud-Based
              Vehicular Traffic Optimization", IEEE Transactions on
              Vehicular Technology, Vol. 65, No. 6, June 2016.

              Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., and D.
              Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+
              for Emergency Service Delivery Optimization",
              IEEE Transactions on Intelligent Transportation Systems,
              June 2017.

   [SANA]     Hwang, T. and J. Jeong, "SANA: Safety-Aware Navigation
              Application for Pedestrian Protection in Vehicular
              Networks", Springer Lecture Notes in Computer Science
              (LNCS), Vol. 9502, December 2015.

   [SDN-DMM]  Nguyen, T., Bonnet, C., and J. Harri, "SDN-based
              Distributed Mobility Management for 5G Networks",
              IEEE Wireless Communications and Networking Conference,
              April 2016.

              Fernandez, P., Santa, J., Bernal, F., and A. Skarmeta,
              "Securing Vehicular IPv6 Communications",
              IEEE Transactions on Dependable and Secure Computing,
              January 2016.

              3GPP, "Study on Enhancement of 3GPP Support for 5G V2X
              Services", 3GPP TS 22.886, June 2018.

              California Partners for Advanced Transportation Technology
              (PATH), "Automated Truck Platooning", [Online] Available:
              connected-vehicles/truck-platooning, 2017.

              3GPP, "Architecture Enhancements for V2X Services", 3GPP
              TS 23.285, June 2018.

              Tsukada, M., Jemaa, I., Menouar, H., Zhang, W., Goleva,
              M., and T. Ernst, "Experimental Evaluation for IPv6 over
              VANET Geographic Routing", IEEE International Wireless
              Communications and Mobile Computing Conference, June 2010.

              Cespedes, S., Lu, N., and X. Shen, "VIP-WAVE: On the
              Feasibility of IP Communications in 802.11p Vehicular
              Networks", IEEE Transactions on Intelligent Transportation
              Systems, vol. 14, no. 1, March 2013.

              Ucar, S., Ergen, S., and O. Ozkasap, "Multihop-Cluster-
              Based IEEE 802.11p and LTE Hybrid Architecture for VANET
              Safety Message Dissemination", IEEE Transactions on
              Vehicular Technology, April 2016.

              Moustafa, H., Bourdon, G., and Y. Gourhant, "Providing
              Authentication and Access Control in Vehicular Network
              Environment", IFIP TC-11 International Information
              Security Conference, May 2006.

   [VNET-MM]  Peng, Y. and J. Chang, "A Novel Mobility Management Scheme
              for Integration of Vehicular Ad Hoc Networks and Fixed IP
              Networks", Springer Mobile Networks and Applications,
              February 2010.

              IEEE 1609 Working Group, "IEEE Guide for Wireless Access
              in Vehicular Environments (WAVE) - Architecture", IEEE Std
              1609.0-2013, March 2014.

              IEEE 1609 Working Group, "IEEE Standard for Wireless
              Access in Vehicular Environments - Security Services for
              Applications and Management Messages", IEEE Std
              1609.2-2016, March 2016.

              IEEE 1609 Working Group, "IEEE Standard for Wireless
              Access in Vehicular Environments (WAVE) - Networking
              Services", IEEE Std 1609.3-2016, April 2016.

              IEEE 1609 Working Group, "IEEE Standard for Wireless
              Access in Vehicular Environments (WAVE) - Multi-Channel
              Operation", IEEE Std 1609.4-2016, March 2016.

Appendix A.  Relevant Topics to IPWAVE Working Group

   This section discusses topics relevant to IPWAVE WG: (i) vehicle
   identity management; (ii) multihop V2X; (iii) multicast; (iv) DNS
   naming services and service discovery; (v) IPv6 over cellular

A.1.  Vehicle Identity Management

   A vehicle can have multiple network interfaces using different access
   network technologies [Identity-Management].  These multiple network
   interfaces mean multiple identities.  To identify a vehicle with
   multiple indenties, a Vehicle Identification Number (VIN) can be used
   as a globally unique vehicle identifier.

   To support the seamless connectivity over the multiple identities, a
   cross-layer network architecture is required with vertical handover
   functionality [Identity-Management].  Also, an AAA service for
   multiple identities should be provided to vehicles in an efficient
   way to allow horizontal handover as well as vertical handover; note
   that AAA stands for Authentication, Authorization, and Accounting.

A.2.  Multihop V2X

   Multihop packet forwarding among vehicles in 802.11-OCB mode shows an
   unfavorable performance due to the common known broadcast-storm
   problem [Broadcast-Storm].  This broadcast-storm problem can be
   mitigated by the coordination (or scheduling) of a cluster head in a
   connected VANET or an RSU in an intersection area, where the cluster
   head can work as a coodinator for the access to wireless channels.

A.3.  Multicast

   IP multicast in vehicular network environments is especially useful
   for various services.  For instance, an automobile manufacturer can
   multicast a particular group/class/type of vehicles for service
   notification.  As another example, a vehicle or an RSU can
   disseminate alert messages in a particular area [Multicast-Alert].

   In general IEEE 802 wireless media, some performance issues about
   multicast are found in [Multicast-802].  Since several procedures and
   functions based on IPv6 use multicast for control-plane messages,
   such as Neighbor Discovery (ND) and Service Discovery,
   [Multicast-802] describes that the ND process may fail due to
   unreliable wireless link, causing failure of the DAD process.  Also,
   the Router Advertisement messages can be lost in multicasting.

A.4.  DNS Naming Services and Service Discovery

   When two vehicular nodes communicate with each other using the DNS
   name of the partner node, DNS naming service (i.e., DNS name
   resolution) is required.  As shown in Figure 2 and Figure 3, a
   recursive DNS server (RDNSS) within an internal network can perform
   such DNS name resolution for the sake of other vehicular nodes.

   A service discovery service is required for an application in a
   vehicular node to search for another application or server in another
   vehicular node, which resides in either the same internal network or
   the other internal network.  In V2I or V2V networking, as shown in
   Figure 2 and Figure 3, such a service discovery service can be
   provided by either DNS-based Service Discovery (DNS-SD) [RFC6763]
   with mDNS [RFC6762] or the vehicular ND with a new option for service
   discovery [ID-Vehicular-ND]. [ID-Vehicular-ND][ID-VND-Discovery].

A.5.  IPv6 over Cellular Networks

   Recently, 3GPP has announced a set of new technical specifications,
   such as Release 14 (3GPP-R14), which proposes an architecture
   enhancements for V2X services using the modified sidelink interface
   that originally is designed for the LTE-D2D communications. 3GPP-R14
   specifies that the V2X services only support IPv6 implementation.
   3GPP is also investigating and discussing the evolved V2X services in
   the next generation cellular networks, i.e., 5G new radio (5G-NR),
   for advanced V2X communications and automated vehicles' applications.

A.5.1.  Cellular V2X (C-V2X) Using 4G-LTE

   Before 3GPP-R14, some researchers have studied the potential usage of
   C-V2X communications.  For example, [VMaSC-LTE] explores a multihop
   cluster-based hybrid architecture using both DSRC and LTE for safety
   message dissemination.  Most of the research considers a short
   message service for safety instead of IP datagram forwarding.  In
   other C-V2X research, the standard IPv6 is assumed.

   The 3GPP technical specification [TS-23.285-3GPP] states that both IP
   based and non-IP based V2X messages are supported, and only IPv6 is
   supported for IP based messages.  Moreover, [TS-23.285-3GPP]
   instructs that a UE autoconfigures a link-local IPv6 address by
   following [RFC4862], but without sending Neighbor Solicitation and
   Neighbor Advertisement messages for DAD.  This is because a unique
   prefix is allocated to each node by the 3GPP network, so the IPv6
   addresses cannot be duplicate.

A.5.2.  Cellular V2X (C-V2X) Using 5G

   The emerging services, functions, and applications, which are
   developped in automotive industry, demand reliable and efficient
   communication infrastructure for road networks.  Correspondingly, the
   support of enhanced V2X (eV2X)-based services by future converged and
   interoperable 5G systems is required.  The 3GPP Technical Report
   [TR-22.886-3GPP] is studying new use cases and the corresponding
   service requirements for V2X (including V2V and V2I) using 5G in both
   infrastructure mode and the sidelink variations in the future.

Appendix B.  Changes from draft-ietf-ipwave-vehicular-networking-05 draft-ietf-ipwave-vehicular-networking-06

   The following changes are made from draft-ietf-ipwave-vehicular-

   o  In Figure 2 1, a vehicular network architecture is modified to show
      a vehicular link model in a multi-link subnet with vehicular
      wireless links.

   o  In Section 5.1, a Vehicular Neighbor Discovery (VND)
      [ID-Vehicular-ND] is introduced along with a vehicular link model
      in a multi-link subnet.  In such a subnet, the description of MAC
      Address Pseudonym, Prefix Dissemination/Exchange, and Figure 3, Routing is

   o  In Section 5.2, a proactive handover is introduced for an
      efficient mobility management with the vehicle networks cooperation among vehicles,
      RSUs, and RSU network are
      updated. MA along with link-layer parameters, such as Received
      Channel Power Indicator (RCPI).

Appendix C.  Acknowledgments

   This work was supported by Basic Science Research Program through the
   National Research Foundation of Korea (NRF) funded by the Ministry of
   Education (2017R1D1A1B03035885).

   This work was supported in part by Global Research Laboratory Program
   through the NRF funded by the Ministry of Science and ICT (MSIT)
   (NRF-2013K1A1A2A02078326) and by the DGIST R&D Program of the MSIT

   This work was supported in part by the French research project
   DataTweet (ANR-13-INFR-0008) and in part by the HIGHTS project funded
   by the European Commission I (636537-H2020).

Appendix D.  Contributors

   This document is a group work of IPWAVE working group, greatly
   benefiting from inputs and texts by Rex Buddenberg (Naval
   Postgraduate School), Thierry Ernst (YoGoKo), Bokor Laszlo (Budapest
   University of Technology and Economics), Jose Santa Lozanoi
   (Universidad of Murcia), Richard Roy (MIT), Francois Simon (Pilot),
   Sri Gundavelli (Cisco), Erik Nordmark, and Dirk von Hugo (Deutsche
   Telekom).  The authors sincerely appreciate their contributions.

   The following are co-authors of this document:

   Nabil Benamar
   Department of Computer Sciences
   High School of Technology of Meknes
   Moulay Ismail University

   Phone: +212 6 70 83 22 36
   EMail: benamar73@gmail.com

   Sandra Cespedes
   Department of Electrical Engineering
   NIC Chile Research Labs
   Universidad de Chile
   Av.  Tupper 2007, Of. 504
   Santiago, 8370451  Blanco Encalada 1975

   Phone: +56 2 29784093
   EMail: scespede@niclabs.cl

   Jerome Haerri
   Communication Systems Department

   Phone: +33 4 93 00 81 34
   EMail: jerome.haerri@eurecom.fr

   Dapeng Liu
   Beijing, Beijing 100022
   Phone: +86 13911788933
   EMail: max.ldp@alibaba-inc.com

   Tae (Tom) Oh
   Department of Information Sciences and Technologies
   Rochester Institute of Technology
   One Lomb Memorial Drive
   Rochester, NY 14623-5603

   Phone: +1 585 475 7642
   EMail: Tom.Oh@rit.edu

   Charles E.  Perkins
   Futurewei Inc.
   2330 Central Expressway
   Santa Clara, CA 95050

   Phone: +1 408 330 4586
   EMail: charliep@computer.org

   Alexandre Petrescu
   CEA Saclay
   Gif-sur-Yvette, Ile-de-France 91190

   Phone: +33169089223
   EMail: Alexandre.Petrescu@cea.fr

   Yiwen Chris Shen
   Department of Computer Science & Engineering
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do 16419
   Republic of Korea

   Phone: +82 31 299 4106
   Fax: +82 31 290 7996
   EMail: chrisshen@skku.edu
   URI: http://iotlab.skku.edu/people-chris-shen.php
   Michelle Wetterwald
   21, Route de Luxembourg
   Wasserbillig, Luxembourg L-6633

   EMail: Michelle.Wetterwald@gmail.com

Author's Address

   Jaehoon Paul Jeong (editor)
   Department of Software
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 299 4957
   Fax:   +82 31 290 7996
   EMail: pauljeong@skku.edu
   URI:   http://iotlab.skku.edu/people-jaehoon-jeong.php