IPWAVE Working Group                                       J. Jeong, Ed.
Internet-Draft                                   Sungkyunkwan University
Intended status: Informational                            March                              May 24, 2019
Expires: September November 25, 2019

IP Wireless Access in Vehicular Environments (IPWAVE): Problem Statement
                             and Use Cases
               draft-ietf-ipwave-vehicular-networking-08
               draft-ietf-ipwave-vehicular-networking-09

Abstract

   This document discusses the problem statement and use cases of IP-
   based vehicular networking for 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 explains 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,  Next, it
   presents makes a problem exploration for
   statement about 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 specifies requirements in IP-based
   vehicular networking. networking, and suggests the direction of solutions
   satisfying those requirements.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4   3
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  V2V . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  V2I . . . . . . . . . . . . . . . . . . . . . . . . . . .   7   6
     3.3.  V2X . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Analysis for Existing Protocols  Vehicular Networks  . . . . . . . . . . . . . . .   8
     4.1.  Existing Protocols for Vehicular Networking . . . . . .   7
     4.1.  Vehicular Network Architecture  .   8
       4.1.1.  IP Address Autoconfiguration . . . . . . . . . . . .   8
       4.1.2.  Routing Protocol  . .
     4.2.  V2I-based Internetworking . . . . . . . . . . . . . . . .   9
       4.1.3.  Mobility Management . . . . . . . . . . . . . . . . .  10
       4.1.4.  DNS Naming Service  .
     4.3.  V2V-based Internetworking . . . . . . . . . . . . . . . .  11
       4.1.5.  Service Discovery . . . . . . . . . . . . . . . . . .  12
       4.1.6.  Security and Privacy  . . . . . . . . . . . . . .
   5.  Problem Statement . .  12
     4.2.  General Problems . . . . . . . . . . . . . . . . . . . .  13
       4.2.1.  Vehicular Network Architecture  . . . . . . . . . . .  14
       4.2.2.  Latency . . . . .
     5.1.  Neighbor Discovery  . . . . . . . . . . . . . . . . . .  19
       4.2.3.  Security .  13
       5.1.1.  Link Model  . . . . . . . . . . . . . . . . . . . . .  20
       4.2.4.  14
       5.1.2.  MAC Address Pseudonym Handling  . . . . . . . . . . . . . . . . .  20
   5.  Problem Exploration . . . . . . . . . . . .  16
       5.1.3.  Prefix Dissemination/Exchange . . . . . . . . .  20
     5.1.  Neighbor Discovery . . .  16
       5.1.4.  Routing . . . . . . . . . . . . . . . .  20
       5.1.1.  Link Model . . . . . . .  17
     5.2.  Mobility Management . . . . . . . . . . . . . .  21
       5.1.2.  MAC Address Pseudonym . . . . .  17
     5.3.  Security and Privacy  . . . . . . . . . . .  22
       5.1.3.  Prefix Dissemination/Exchange . . . . . . .  18
   6.  Security Considerations . . . . .  22
       5.1.4.  Routing . . . . . . . . . . . . . .  19
   7.  Informative References  . . . . . . . . .  22
     5.2.  Mobility Management . . . . . . . . . .  19
   Appendix A.  Changes from draft-ietf-ipwave-vehicular-
                networking-08  . . . . . . . . .  23
     5.3.  Security and Privacy . . . . . . . . . .  25
   Appendix B.  Acknowledgments  . . . . . . . .  24
   6.  Security Considerations . . . . . . . . . .  25
   Appendix C.  Contributors . . . . . . . . .  24
   7.  Informative References . . . . . . . . . . .  25
   Author's Address  . . . . . . . .  25
   Appendix A.  Relevant Topics to IPWAVE Working Group . . . . . .  33
     A.1.  Vehicle Identity Management . . . . . . . . . . . . . . .  33
     A.2.  Multihop V2X  . . . . . . . . . . . . . . . . . . . . . .  33
     A.3.  Multicast . . . . . . . . . . . . . . . . . . . . . . . .  33
     A.4.  DNS Naming Services and Service Discovery . . . . . . . .  34
     A.5.  IPv6 over Cellular Networks . . . . . . . . . . . . . . .  34
       A.5.1.  Cellular V2X (C-V2X) Using 4G-LTE . . . . . . . . . .  34
       A.5.2.  Cellular V2X (C-V2X) Using 5G . . . . . . . . . . . .  35
   Appendix B.  Changes from draft-ietf-ipwave-vehicular-
                networking-07  . . . . . . . . . . . . . . . . . . .  35
   Appendix C.  Acknowledgments  . . . . . . . . . . . . . . . . . .  35
   Appendix D.  Contributors . . . . . . . . . . . . . . . . . . . .  36
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  38  27

1.  Introduction

   Vehicular networking studies have mainly focused on improving safety
   and efficiency, and also enabling entertainment in vehicular
   networks.  The Federal Communications Commission (FCC) in the US
   allocated wireless channels for Dedicated Short-Range Communications
   (DSRC) [DSRC], service [DSRC] in the Intelligent Transportation Systems (ITS) Radio Service in with
   the frequency band of 5.850 - 5.925 GHz band (5.9 (i.e., 5.9 GHz band).
   DSRC-based  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 a 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.  The Physical Layer (L1) and Data Link
   Layer (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 was a
   separate standard, but was later enrolled into the base 802.11
   standard (IEEE 802.11-2012) as IEEE 802.11 Outside the Context of a
   Basic Service Set in 2012 [IEEE-802.11-OCB].

   Along with these WAVE standards, IPv6 [RFC8200] and Mobile IP
   protocols (e.g., MIPv4 [RFC5944], MIPv6 [RFC6275], and Proxy MIPv6
   (PMIPv6) [RFC5213][RFC5844]) 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) [ISO-ITS-IPv6].

   This document discusses problem statements and explains use cases related to
   IP-based and a problem statement about IP-
   based vehicular networking for Intelligent Transportation Systems
   (ITS), ITS, which is denoted as named IP Wireless Access
   in Vehicular Environments (IPWAVE).  First, it surveys introduces the use
   cases for using V2V, V2I, and V2X networking in the ITS.  Second, for literature
   review,  Next, it analyzes proposed protocols for IP-based vehicular
   networking and highlights the limitations and difficulties found on
   those protocols.  Third, for
   makes a problem statement, it presents a problem
   exploration with statement about 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 this document specifies
   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, networking, and IPv6 over Cellular Networks. proposes the
   direction of solutions fulfilling those requirements.  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
   networks.
   networks in near future.

2.  Terminology

   This document uses the following definitions:

   o  DMM: Acronym for "Distributed Mobility Management"
      [RFC7333][RFC7429].

   o  LiDAR: Acronym for "Light Detection and Ranging".  It is a
      scanning device to measure a distance to an object by emitting
      pulsed laser light and measuring the reflected pulsed light.

   o  Mobility Anchor (MA): A node that maintains IP addresses and
      mobility information of vehicles in a road network to support
      their address autoconfiguration and mobility management with a
      binding table.  It has end-to-end connections with RSUs under its
      control.

   o  On-Board Unit (OBU): A node that has physical communication
      devices (e.g., IEEE 802.11-OCB and Cellular V2X (C-V2X)
      [TS-23.285-3GPP]) 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  OCB: Acronym for "Outside the Context of a Basic Service Set"
      [IEEE-802.11-OCB].

   o  Road-Side Unit (RSU): A node that has physical communication
      devices (e.g., IEEE 802.11-OCB and C-V2X) 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  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.

   o  Vehicle: A node that has an OBU for wireless communication with
      other vehicles and RSUs.  It has a radio navigation receiver of
      Global Positioning System (GPS) for efficient navigation.

   o  Vehicular Ad Hoc Network (VANET): A network that consists of
      vehicles interconnected by wireless communication.  Since VANET is
      a connected network component, two vehicles in a VANET can
      communicate with each other through ad hoc routing via other
      vehicles as relays even where they are out of one-hop wireless
      communication range.

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

   o  Vehicle Detection Loop (or (i.e., Loop Detector): An inductive device
      used for detecting vehicles passing or arriving at a certain
      point, for instance approaching a instance, at an intersection with traffic light lights or in motorway
      traffic. at
      a ramp toward a highway.  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  V2I2P: Acronym for "Vehicle to Infrastructure to Pedestrian".

   o  V2I2V: Acronym for "Vehicle to Infrastructure to Vehicle".

   o  WAVE: Acronym for "Wireless Access in Vehicular Environments"
      [WAVE-1609.0].

3.  Use Cases

   This section provides explains 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
      avoidance;

   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
   vehicles.

   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 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.  Thus, CACC can
   help adjacent vehicles to efficiently adjust their speed in an
   interactive way through V2V networking in order to avoid collision.

   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 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 the
   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 version of SAINT
   [SAINTplus] can give the fast moving paths to emergency vehicles
   (e.g., ambulance and fire engine) to let them reach an accident spots spot
   while providing other vehicles near the accident spot 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 the 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 a network device for wireless communication (e.g.,
   WiFi) with an RSU (e.g., WiFi). RSU.  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 the 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  IP address autoconfiguration;

   o  Routing protocol;

   o  Mobility management;

   o  DNS naming service;

   o  Service discovery;

   o  Security and privacy.

4.1.1.  IP Address Autoconfiguration

   For IP address autoconfiguration, Fazio et al. proposed Networks

   This section describes 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 network architecture supporting
   V2V, V2I, 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 V2X communications in vehicular
   networks (i.e., employing multiple access technologies) networks.  Also, it
   describes an internal network within a
   comprehensive study of vehicle or RSU, and the cross-layer identity management, which
   constitutes a fundamental element of
   internetworking between the ITS architecture
   [Identity-Management]. internal networks via DSRC links.

                     Traffic Control Center in Vehicular Cloud
                    *-----------------------------------------*
                   *                                           *
                  *             +----------------+              *
                 *              | Mobility Anchor|               *
                 *              +----------------+               *
                  *                      ^                      *
                   *                     |                     *
                    *--------------------v--------------------*
                    ^               ^                        ^
                    |               |                        |
                    |               |                        |
                    v               v                        v
               +--------+ Ethernet +--------+            +--------+
               |  RSU1  |<-------->|  RSU2  |<---------->|  RSU3  |
               +--------+          +--------+            +--------+
                  ^                     ^                    ^
                  :                     :                    :
           +-----------------+ +-----------------+   +-----------------+
           |      : V2I      | |    V2I :        |   |   V2I :         |
           |      v          | |        v        |   |       v         |
+--------+ |   +--------+    | |   +--------+    |   |   +--------+    |
|Vehicle1|===> |Vehicle2|===>| |   |Vehicle3|===>|   |   |Vehicle4|===>|
|        |<...>|        |<........>|        |    |   |   |        |    |
+--------+ V2V +--------+    V2V   +--------+    |   |   +--------+    |
           |                 | |                 |   |                 |
           +-----------------+ +-----------------+   +-----------------+
                 Subnet1              Subnet2              Subnet3

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

   Figure 1: A server-based address autoconfiguration such as VAC
   [Address-Autoconf] takes some delay Vehicular Network Architecture for V2I and V2V Networking

4.1.  Vehicular Network Architecture

   Figure 1 shows an architecture for V2I and V2V networking in a vehicle to join a new
   cluster (i.e., a connected VANET) road
   network.  As shown in this figure, RSUs as routers and communicate with neighboring
   vehicles.  This delay may prevent vehicles from exchaning safety
   messages with each other in a prompty way.  It will be good
   OBU have wireless media interfaces for a
   vehicle to maintain its IP address even when VANET.  Also, it joins another
   cluster.  A geographical-position-based address autoconfiguration, is assumed
   that such as the wireless media interfaces are autoconfigured with a
   global IPv6 prefix allocation per lane [Address-Assignment] (e.g., 2001:DB8:1:1::/64) to support both V2V and a
   prefix allocation per geographic region [GeoSAC], causes the frequent
   change of a vehicle's IP
   V2I networking.

   Especially, 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 and requires the DAD
   mapping for the
   uniqueness test unicast and multicast, stateless autoconfiguration, and
   subnet structure.  Especially, an Ethernet Adaptation (EA) layer is
   in charge of a new IP address.  This transforming some parameters between IEEE 802.11 MAC
   layer and IPv6 network layer, which is significant overhead
   for high-speed moving vehicles.  It will located between IEEE
   802.11-OCB's logical link control layer and IPv6 network layer.  This
   IPv6 over 802.11-OCB can be efficient used for a vehicle
   to be able to use its IP address while moving across the clusters both V2V and
   geographical regions.  For V2I in IP-based
   vehicular networks.

   In Figure 1, three RSUs (RSU1, RSU2, and RSU3) are deployed in the cross-layer identity management with
   multiple wireless interfaces [Identity-Management], it will be
   necessary
   road network and are connected to maintain an upper-layer session (e.g., TCP session) of a
   vehicle with multiple IP addresses corresponing Vehicular Cloud through the
   Internet.  A Traffic Control Center (TCC) is connected to the multiple
   wireless interfaces.

4.1.2.  Routing Protocol

   For vehicular routing, Abboud et al. proposed a cluster-based routing
   [Cluster-Based-Routing].  Vehicles construct clusters along with
   their location and speed information
   Vehicular Cloud for fast data dissemination
   among the clusters.  They consist management of cluster headers, cluster
   gateways and cluster members for intra-cluster and inter-cluster
   communications.  Tsukada et al. presented a work that aims at
   combining IPv6 networking RSUs and a Car-to-Car Network (called C2CNet)
   routing protocol proposed by the Car-to-Car Communication Consortium
   (C2C-CC).  Note that C2CNet is vehicles in the network layer of road
   network.  A Mobility Anchor (MA) is located in the C2C-CC
   communication system and uses a geographic routing protocol for
   vehicular networks [VANET-Geo-Routing].  Abrougui et al. presented a
   gateway discovery scheme TCC as its key
   component for the mobility management of vehicles.  Two vehicles
   (Vehicle1 and Vehicle2) are wirelessly connected to access the Internet via a
   gateway, called Location-Aided Gateway Advertisement RSU1, and Discovery
   (LAGAD) mechanism [LAGAD].  A one
   vehicle (as a packet source) multihop
   away from a gateway can discover the gateway and deliver its packets (Vehicle3) is wirelessly connected to the gateway through the packet forwarding RSU2.  The wireless
   networks of intermediate vehicles
   (as relay vehicles) RSU1 and RSU2 belong to two different subnets (denoted as
   Subnet1 and Subnet2), respectively.  Also, another vehicle (Vehicle4)
   is wireless connected to RSU3, belonging to another subnet (denoted
   as Subnet3).

   In wireless subnets in vehicular networks (e.g., Subnet1 and Subnet2
   in Figure 1), vehicles can construct a connected VANET.  Those intermediate
   vehicles VANET (with an
   arbitrary graph topology) and can communicate with each other via V2V
   communication.  Vehicle1 can communicate with Vehicle2 via V2V
   communication, and Vehicle2 can communicate with Vehicle3 via V2V
   communication because they are located between within the packet source vehicle and wireless communication
   range for each other.  On the other hand, Vehicle3 can communicate
   with Vehicle4 via the
   gateway.

   For data packet routing in vehicular networks, multihop V2V infrastructure (i.e., RSU2 and
   multihop RSU3)
   by employing V2I communications (i.e., V2I2V) communication because they are required.  For multihop V2V
   communications not
   within a connected VANET, a cluster-based routing like
   [Cluster-Based-Routing] the wireless communication range for each other.

   In vehicular networks, unidirectional links exist and must be
   considered for wireless communications.  Also, in the vehicular
   networks, control plane can play a role of be separated from data plane for
   efficient mobility management and data forwarding
   through a virtual backbone of cluster headers and cluster gateways.
   For this, an efficient cluster formation is performed through sharing
   the using Software-
   Defined Networking (SDN) [SDN-DMM].  The mobility information (e.g., position, direction, and speed) of
   vehicles.  But the pure VANET-based clustering will cause significant
   control messages and need some delay for cluster formation, so
   vehicles can perform clustering through infrastructure nodes a
   GPS receiver mounted in its vehicle (e.g.,
   RSUs trajectory, position,
   speed, and base stations) via cellular links, which guarantees always-
   network-connection.

   For multihop V2I communications, a gateway discovery scheme like
   LAGAD [LAGAD] direction) can be used through a connected VANET having a
   connection with an Internet gateway.  However, this reactive gateway
   discovery causes much control messages for the discovery and need
   some delay until a packet source vehicle accommodation of mobility-
   aware proactive protocols.  Vehicles can transmit its packets
   toward use the gateway.  Thus, a proactive gateway discovery is required
   over a connected VANET where vehicles share routes towards gateways
   (e.g., distance vector information to gateways) in TCC as their Home
   Network having a proactive
   manner.

4.1.3.  Mobility Management

   For home agent for mobility management, Chen et al. tackled the issue of network
   fragmentation management as in VANET environments [IP-Passing-Protocol] by
   proposing a protocol that can postpone the time to release IP
   addresses to the DHCP server MIPv6
   [RFC6275] and select a faster way to get the
   vehicle's new IP address, when PMIPv6 [RFC5213], so the vehicle density is low or TCC maintains the
   speeds mobility
   information of vehicles are highly variable.  Nguyen et al. proposed a
   hybrid centralized-distributed mobility management called H-DMM to
   support for location management.  Also, IP tunneling
   over the mobility of high-speed mobile vehicles, which is based on
   both DMM and PMIPv6 [H-DMM].  They also proposed a hybrid
   centralized-distributed mobility management wireless link should be avoided for network mobility
   called H-NEMO to support performance efficiency.

4.2.  V2I-based Internetworking

   This section discusses the efficient mobility of mobile nodes and
   mobile routers internetworking between different subnets, which is based on both DMM
   and PMIPv6 [H-NEMO].

   [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 vehicle's
   internal network mobility protocol to reduce handoff delay (i.e., moving network) and maintain Internet connectivity an RSU's internal network
   (i.e., fixed network) via V2I communication.

                                                    +-----------------+
                           (*)<........>(*)  +----->| Vehicular Cloud |
          2001:DB8:1:1::/64 |            |   |      +-----------------+
   +------------------------------+  +---------------------------------+
   |                        v     |  |   v   v                         |
   | +-------+ +------+ +-------+ |  | +-------+ +------+ +-------+    |
   | | Host1 | | DNS1 | |Router1| |  | |Router3| | DNS2 | | 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

   Nowadays, a vehicle's internal network tends to moving vehicles be Ethernet to
   interconnect electronic control units in a highway
   [NEMO-VANET].  Lee et al. proposed P-NEMO, which is a PMIPv6-based IP
   mobility management scheme vehicle.  It can also
   support WiFi and Bluetooth to maintain the Internet connectivity at
   the vehicle as accommodate a driver's and passenger's
   mobile network, devices (e.g., smartphone and provides a make-before-break
   mechanism when vehicles switch tablet).  In this trend, it is
   reasonable to consider 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].  This scheme uses both a road vehicle's internal network layout (i.e., moving
   network) and also the
   wireless coverage of multiple base stations in order to improve the
   connectivity of vehicles to interaction between the Internet internal network and decrease an
   external network within another vehicle or RSU.

   As shown in Figure 2, the overhead of
   mobility management.  Nguyen et al. extended their previous works
   (i.e., H-DMM [H-DMM] vehicle's moving network and H-NEMO [H-NEMO]) on a vehicular DMM by using
   a Software-Defined Networking (SDN) architecture, which separates the
   control plane RSU's
   fixed network are self-contained networks having multiple subnets and
   having an edge router for the data plane in network functionality [SDN-DMM].

   A communication with another vehicle can have an or
   RSU.  Internetworking between two internal network for its in-vehicle devices and
   passengers' mobile devices.  In this case, vehicular networks need to
   support not only the host mobility for the vehicle, but also the
   network mobility of such via V2I
   communication requires an internet exchange of network within the vehicle.  The
   current mobility management schemes, prefix and other
   parameters through a prefix discovery mechanism, such as [H-DMM] and [H-NEMO],
   are not enough to support both ND-based
   prefix discovery [ID-Vehicular-ND].  For the host mobility and ND-based prefix
   discovery, network mobility
   in an efficient way.  An efficient mobility management scheme can
   take advantage of prefixs and parameters should be registered into a
   vehicle's mobility information (e.g., position,
   direction, and speed) router and partial or full trajectory (i.e., a
   navigation path in a road network) an RSU router with an external network interface
   in order to perform operations advance.

   The network parameter discovery collects networking information for
   mobility management proactively.  For this proactive mobility
   management,
   an SDN-based mobility management scheme like [SDN-DMM]
   will be promising because SDN controllers can proactively set up
   forwarding tables for traffic flows of vehicles with their mobility IP communication between a vehicle and trajectory an RSU or between two
   neighboring vehicles, such as link layer, MAC layer, and IP layer
   information.

4.1.4.  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 link layer information includes wireless link layer
   parameters, such as wireless media (e.g., IEEE 802.11-OCB and LTE-
   V2X) and a transmission power level.  The MAC layer information
   includes the corresponding IP MAC address in multicast.  DNS Name
   Autoconfiguration (DNSNA) [ID-DNSNA] proposes a DNS naming service of an external network interface for Internet-of-Things (IoT) devices in a large-scale network.

   A DNS name resolution service needs to support DNS name resolution the
   internetworking with another vehicle or RSU.  The IP layer
   information includes the IP address and prefix of an external network
   interface for in-vehicle devices the internetworking with another vehicle or RSU.

   Once the network parameter discovery and passengers' mobile devices within a
   vehicle's internal network, which prefix exchange operations
   have been performed, packets can be called intra-vehicle DNS
   name resolution.  Also, it needs to support DNS name resolution transmitted between devices (e.g., cooperative cruise control device) existing in
   different vehicles, which can be called inter-vehicle the vehicle's
   moving network and the RSU's fixed network.  DNS name
   resolution.  In addition, it need services should be
   supported to support DNS enable name resolution in for hosts or servers as corresponding nodes residing
   either in the Internet, which can be
   called global DNS name resolution.

   For vehicle's moving network or the RSU's fixed network.
   It is assumed that the intra-vehicle DNS name resolution names of in-vehicle devices and inter-vehicle DNS name
   resolution, both mDNS [RFC6762] and DNSNA [ID-DNSNA] can be used, but
   they perform DNS name resolution in a reactive way.  That is, when a
   DNS query is given by a querier, it will be multicasted to devices
   through mDNS or be unicasted to a dedicated their
   service names are registered into a DNS server through DNSNA,
   respectively.

   For the inter-vehicle DNS name resolution in fast-moving vehicles, a
   proactive DNS resolution can be performed by the help of an RSU that
   collects the DNS information of vehicles and disseminate it to
   vehicles under its coverage.

   For the global DNS name resolution, a vehicle can use an RSU's DNS
   server (or a DNS server close to or an RSU
   RSU, as shown in the wired network) to
   perform a DNS resolution for the sake of Figure 2.

   Figure 2 shows internetworking between the vehicle's device during
   its travel.  When the DNS resolution is finished by moving network
   and the RSU's DNS
   server, fixed network.  There exists an internal network
   (Moving Network1) inside Vehicle1.  Vehicle1 has the DNS server can forward Server
   (DNS1), the DNS resolution result to two hosts (Host1 and Host2), and the
   vehicle through two routers (Router1
   and Router2).  There exists another internal network (Fixed Network1)
   inside RSU1.  RSU1 has the current RSU providing DNS Server (DNS2), one host (Host3), the vehicle with
   two routers (Router3 and Router4), and the
   Internet connectivity.

4.1.5.  Service Discovery

   To discover instances collection of a demanded service servers
   (Server1 to ServerN) for various services in vehicular the road 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 such
   as the prefix emergency notification and service discovery
   with new ND options.

   For vehicular networks, DNSNA can navigation.  Vehicle1's Router1
   (called mobile router) and RSU1's Router3 (called fixed router) use a dedicated DNS server residing
   in an RSU or close to
   2001:DB8:1:1::/64 for an RSU in the wired network [ID-DNSNA].  In
   this case, in-vehicle devices can register their services external link (e.g.,
   cooperative cruise control service and navigation service) into the
   DNS server.  When the DNS server can receive a service discovery
   query from vehicles via an RSU, it can resolve it quickly for them.
   In DNSNA, these DNS query and response messages are delivered in
   unicast rather than multicast, so the wireless channel will be
   utilized efficiently DSRC) for DNS resolution including service discovery. I2V
   networking.  Thus, DNSNA will provide a more efficient service discovery to
   vehicles one host (Host1) in a high-vehicle-density environment than mDNS [RFC6762]
   and Vehicular ND [ID-Vehicular-ND].  This is because a DNS query for
   service discovery is unicasted by DNSNA, but it is multicasted by
   both mDNS and Vehicular ND.

   In a V2V scenario such as the case where a dedicated DNS Vehicle1 can communicate with
   one server (Server1) in an
   RSU is not available RSU1 for the registration and sharing of service
   information, Vehicular ND can provide vehicles with rapid service
   discovery by letting vehicles proactively advertise their service
   information with Neighbor Advertisement (NA) messages.  Thus,
   considering both V2I and V2V scenarios, an efficient service
   discovery scheme can be designed.

4.1.6.  Security and Privacy

   For security and privacy, Fernandez et al. proposed a secure vehicular IPv6 communication scheme using Internet Key Exchange
   version 2 (IKEv2) service through
   Vehicle1's moving network, a wireless link between Vehicle1 and Internet Protocol Security (IPsec) for
   vehiculer networks. RSU1,
   and RSU1's fixed network.

4.3.  V2V-based Internetworking

   This scheme provides section discusses the secure communication
   channel internetworking between a home agent and a mobile router to support the
   network mobility of a vehicle's internal network [Securing-VCOMM].
   Moustafa et al. proposed a security scheme providing authentication,
   authorization, and accounting (AAA) services in vehicular networks

   [VNET-AAA].  The vehicular moving
   networks consist of VANETs as a front end
   and an access network as a back end via an access point.  The
   security scheme provides two neighboring vehicles with an efficient AAA service for
   the network connectivity during their movement in the road network.

   Security services in vehicular networks need to support an efficient
   AAA for the accommodation of only valid vehicles and a secure
   communication with IKEv2 and IPsec between vehicles or between a
   vehicle and the corresponding node in the Internet.  For the
   efficiency, these security services need to take advantage of a
   vehicular network architecture having a TCC and RSUs as well as a
   vehicle's mobility and trajectory information.

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
                    *-----------------------------------------*
                   *                                           *
                  *             +----------------+              *
                 * via V2V communication.

                           (*)<..........>(*)
          2001:DB8:1:1::/64 |              |
   +------------------------------+  +------------------------------+
   |                        v     |  |     v                        |
   | +-------+ +------+ +-------+ |  | +-------+ +------+ +-------+ |
   | | Host1 | | DNS1 | |Router1| |  | |Router5| | DNS3 | | Host4 | |
   | +-------+ +------+ +-------+ |  | +-------+ +------+ +-------+ |
   | Mobility Anchor|               *
                 *              +----------------+               *
                  *     ^                      *
                   *        ^         ^     |  |                     *
                    *--------------------v--------------------*     ^         ^        ^     |
   |     |        |         |     |  |     |         |        |     |
   |     v        v         v
               +--------+ Ethernet +--------+            +--------+     |  RSU1  |<-------->|  RSU2  |<---------->|  RSU3  |
               +--------+          +--------+            +--------+
                  ^     v         v        v     |
   | ---------------------------- |  | ---------------------------- |
   | 2001:DB8:10:1::/64 ^         |  |         ^
                  :                     :                    :
           +--------------------------------------+ +------------------+ 2001:DB8:30:1::/64 |
   |                    |         |      : V2I             V2I :  |         |    V2I :                    |
   |      v                    v         |  |         v                    |
+--------+
   |   +--------+          +--------+ +-------+      +-------+     |  |    +--------+     +-------+      +-------+ |
|Vehicle1|===> |Vehicle2|===>      |Vehicle3|===>
   | |    |Vehicle4|===>| Host2 |        |<...>|        |<........>|      |Router2|     |  |     |Router6|      | Host5 | |
   |
+--------+ V2V +--------+    V2V   +--------+ +-------+      +-------+     |  |    +--------+     +-------+      +-------+ |
   |     ^              ^         |  |         ^              ^     |
           +--------------------------------------+ +------------------+
                           Subnet1                         Subnet2

        <---->
   |     |              |         |  |         |              |     |
   |     v              v         |  |         v              v     |
   | ---------------------------- |  | ---------------------------- |
   |      2001:DB8:10:2::/64      |  |       2001:DB8:30:2::/64     |
   +------------------------------+  +------------------------------+
      Vehicle1 (Moving Network1)        Vehicle2 (Moving Network2)

      <----> Wired Link   <....> Wireless Link   ===> Moving Direction   (*) Antenna

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

4.2.1.  Vehicular Network Architecture 3: Internetworking between Two Vehicle Networks

   Figure 1 3 shows internetworking between the moving networks of two
   neighboring vehicles.  There exists an architecture for V2I internal network (Moving
   Network1) inside Vehicle1.  Vehicle1 has the DNS Server (DNS1), the
   two hosts (Host1 and V2V networking in a road
   network.  As shown in this figure, RSUs as Host2), and the two routers (Router1 and vehicles with
   OBU have wireless media interfaces for VANET.  Also, it is assumed
   that such
   Router2).  There exists another internal network (Moving Network2)
   inside Vehicle2.  Vehicle2 has the wireless media interfaces are autoconfigured with a
   global IPv6 prefix (e.g., 2001:DB8:1:1::/64) to support both V2V DNS Server (DNS3), the two hosts
   (Host4 and
   V2I networking.

   Especially, 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 Host5), and multicast, stateless autoconfiguration, the two routers (Router5 and
   subnet structure.  Especially, Router6).
   Vehicle1's Router1 (called mobile router) and Vehicle2's Router5
   (called mobile router) use 2001:DB8:1:1::/64 for an Ethernet Adaptation (EA) layer is external link
   (e.g., DSRC) for V2V networking.  Thus, one host (Host1) in charge of transforming some parameters Vehicle1
   can communicate with one host (Host4) in Vehicle1 for a vehicular
   service through Vehicle1's moving network, a wireless link between IEEE 802.11 MAC
   layer and IPv6 network layer, which is located between IEEE
   802.11-OCB's logical link control layer
   Vehicle1 and IPv6 network layer.  This
   IPv6 over 802.11-OCB can be used for both V2V Vehicle2, and V2I in IP-based
   vehicular networks.

   In Vehicle2's moving network.

        (*)<..................>(*)<..................>(*)
         |                      |                      |
   +-----------+          +-----------+          +-----------+
   |           |          |           |          |           |
   | +-------+ |          | +-------+ |          | +-------+ |
   | |Router1| |          | |Router5| |          | |Router7| |
   | +-------+ |          | +-------+ |          | +-------+ |
   |           |          |           |          |           |
   | +-------+ |          | +-------+ |          | +-------+ |
   | | Host1 | |          | | Host4 | |          | | Host6 | |
   | +-------+ |          | +-------+ |          | +-------+ |
   |           |          |           |          |           |
   +-----------+          +-----------+          +-----------+
      Vehicle1               Vehicle2               Vehicle3

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

      Figure 1, three RSUs (RSU1, RSU2, and RSU3) are deployed in the
   road network and are connected to a Vehicular Cloud through the
   Internet.  A Traffic Control Center (TCC) is connected to the
   Vehicular Cloud for 4: Multihop Internetworking between Two Vehicle Networks

   Figure 4 shows multihop internetworking between the management moving networks
   of RSUs and two vehicles in the road
   network.  A Mobility Anchor (MA) is located same VANET.  For example, Host1 in the TCC as its key
   component for the mobility management of vehicles.  Two vehicles
   (Vehicle1 and Vehicle2) are wirelessly connected to RSU1, and one
   vehicle (Vehicle3) Vehicle1
   can communicate with Host6 in Vehicle3 via Router 5 in Vehicle2 that
   is wirelessly an intermediate vehicle being connected to RSU2.  The wireless
   networks of RSU1 Vehicle1 and RSU2 belong to Vehicle3
   in a multi-link subnet (denoted linear topology as
   Subnet1) with shown in the same network prefix.  Thus, these three vehicles
   are within the same subnet.  On figure.

5.  Problem Statement

   This section makes a problem statement about key topics for IPWAVE
   WG, such as neighbor discovery, mobility management, and security &
   privacy.

5.1.  Neighbor Discovery

   IPv6 Neighbor Discovery (IPv6 ND) [RFC4861][RFC4862] is a core part
   of the other hand, another vehicle
   (Vehicle4) IPv6 protocol suite.  IPv6 ND is wireless connected designed for point-to-point
   links and transit links (e.g., Ethernet).  It assumes an efficient
   and reliable support of multicast from the link layer for various
   network operations such as MAC Address Resolution (AR) and Duplicate
   Address Detection (DAD).

   IPv6 ND needs to RSU4, belonging be extended to another subnet
   (denoted as Subnet2).  That is, the first three vehicles (i.e.,
   Vehicle1, Vehicle2, vehicular networking (e.g., V2V, V2I,
   and Vehicle3) V2X) in terms of DAD and the last vehicle (i.e.,
   Vehicle4) ND-related parameters (e.g., Router
   Lifetime).  The vehicles are located in moving fast within the two different subnets.

   In wireless subnets in communication
   coverage of a vehicular networks node (e.g., Subnet 1 vehicle and Subnet
   2 in Figure 1), RSU).  Before the
   vehicles can construct exchange application messages with each other, they need
   to be configured with a connected VANET (as an
   arbitrary graph topology) link-local IPv6 address or a global IPv6
   address, and can communicate with recognize each other via V2V
   communication.  Vehicle1 in the aspect of IPv6 ND.

   The legacy DAD assumes that a node with an IPv6 address can communicate reach any
   other node with Vehicle2 via V2V
   communication, the scope of its address at the time it claims its
   address, and Vehicle2 can communicate with Vehicle3 via V2V
   communication because they are hear any future claim for that address by another
   party within the same subnet along their
   IPv6 addresses, which are based on scope of its address for the same prefix.  On duration of the other
   hand, Vehicle3 address
   ownership.  However, the partioning and merging of VANETs makes this
   assumption frequently invalid in vehicular networks.

   The vehicular networks need to support a vehicular-network-wide DAD
   by defining a scope that is compatible with the legacy DAD, and two
   vehicles can communicate with Vehicle4 via RSU2 and RSU3
   employing V2I (i.e., V2I2V) each other when there exists a
   communication because they are within path over VANET or a combination of VANETs and RSUs, as
   shown in Figure 1.  By using the
   two different subnets along with vehicular-network-wide DAD, vehicles
   can assure that their IPv6 addresses, which addresses are
   based on unique in the two different prefixes.

   In vehicular networks, unidirectional links exist and must be
   considered for wireless communications.  Also, in
   network whenever they are connected to the vehicular
   networks, control plane must be separated infrastructure
   or become disconnected from data plane for
   efficient mobility management and data forwarding using Software-
   Defined Networking (SDN) [SDN-DMM].  The mobility information it in the form of VANET.  Even though a
   GPS receiver mounted in its vehicle (e.g., trajectory, position,
   speed, and direction)
   unique IPv6 address can be used for the accommodation derived from a globally unique MAC
   address, this derivation yields a privacy issue of mobility-
   aware proactive protocols.  Vehicles can use the TCC as their Home
   Network having a home agent for mobility management vehicle as in MIPv6
   [RFC6275] an
   IPv6 node.  The vehicular infrastructure having RSUs and PMIPv6 [RFC5213], so an MA can
   participate in the TCC maintains vehicular-network-wide DAD for the mobility
   information sake of
   vehicles for location management.  Also, IP tunneling
   over the wireless link [RFC6775][RFC8505].

   ND time-related parameters such as router lifetime and Neighbor
   Advertisement (NA) interval should be avoided for performance efficiency.

   Cespedes et al. proposed a vehicular IP in WAVE called VIP-WAVE adjusted for
   I2V high-speed
   vehicles 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 density.  As vehicles move faster, the NA
   interval should decrease (e.g., RSU), either.  To overcome these limitations of from 1 sec to 0.5 sec) for the standard
   WAVE, VIP-WAVE enhances NA
   messages to reach the standard WAVE by neighboring vehicles promptly.  Also, as
   vehicle density is higher, the following three
   schemes:

   1.  An efficient mechanism NA interval should increase (e.g.,
   from 0.5 sec to 1 sec) for the IPv6 address assignment and DAD

   2.  An on-demand IP mobility management based on PMIPv6 [RFC5213]

   3.  One-hop and two-hop communication scheme for V2I networking

   Note that VIP-WAVE supports at most two-hop V2I communication for
   simple forwarding operations in VANET.  This NA messages to reduce collision
   probability with other NA messages.

   When ND is because used in vehicular networks, the multi-hop
   V2I communication with more than delay (i.e.,
   latency) between two hops requires an additional
   VANET routing protocol.  Such a multi-hop V2I communication will be
   required for vehicles in a highway with sparsely deployed RSUs in
   order to provide them with the Internet connectivity via V2I.

   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] be bounded to a certain
   threshold (e.g., 500 ms) for nodes' mobility collision-avoidance message exchange
   [CASD].  For IP-based safety applications (e.g., context-aware
   navigation, adaptive cruise control, and link variability.
   However, platooning) in vehicular
   network, this ad-hoc link model bounded data delivery is critical.  The real
   implementations for such applications are not clearly defined available yet.  Thus,
   ND needs to appropriately operate to support the
   efficient V2V and V2I for vehicles with a wireless interface
   configured with an IP-based safety
   applications.

5.1.1.  Link Model

   IPv6 address.

   Petrescu et al. proposed the joint IP networking and radio
   architecture protocols work under certain assumptions for V2V and V2I communication the link model that
   do not necessarily hold in [Joint-IP-Networking].
   The radio architecture uses Wi-Fi for a vehicular wireless link rather than IEEE
   802.11-OCB.  The proposed architecture considers an IP topology [VIP-WAVE]
   [RFC5889].  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
   similar way as result, a radio new vehicular
   link topology, in model is required for a dynamically changing vehicular wireless
   link.

   There is a relationship between a link and prefix, besides the sense
   different scopes that an IP subnet
   would correspond to are expected from the range of 1-hop vehicular communication.  This
   architecture defines three link-local and global
   types of vehicles: Leaf Vehicle, Range
   Extending Vehicle, and Internet Vehicle.  Leaf Vehicle IPv6 addresses.  In an IPv6 link, it is like a
   vehicle assumed that all
   interfaces which are configured with OBU the same subnet prefix and has one external WiFi interface along with
   on-link bit set can communicate with each other on an
   MR.  This MR supports the network mobility IP link.

   A VANET can have multiple links between pairs of a user's mobile device
   and in-vehicle devices vehicles within
   wireless communication range, as shown in the vehicle's internal network.  Range
   Extending Vehicles has Figure 4.  When two external Wi-Fi interfaces
   vehicles belong to connect two
   Wi-Fi subnets the same VANET, but they are out of cars in a train.  Internet Vehicle has one Wi-Fi
   interface for wireless
   communication range, they cannot communicate directly with each
   other.  Assume that a car's subnet and one Wireless Metropolitan Area
   Network (WMAN) interface for the Internet connectivity.  However,
   this architecture global-scope IPv6 prefix is not suitable for assigned to VANETs
   in vehicular networks.  Even though two vehicles with a small size and
   with a wireless interface for V2V and V2I in vehicular links.

4.2.1.1.  V2I-based Internetworking

   This section discusses the internetworking between same VANET
   configure their IPv6 addresses with the same IPv6 prefix, they may
   not communicate with each other not in a vehicle's moving one hop in the same VANET
   because of the multihop network connectivity.  Thus, in this case,
   the concept of a on-link IPv6 prefix does not hold because two
   vehicles with the same on-link IPv6 prefix cannot communicate
   directly with each other.  Also, when two vehicles are located in two
   different VANETs with the same IPv6 prefix, they cannot communicate
   with each other.  When these two VANETs are converged into one VANET,
   the two vehicles can communicate with each other in a multihop
   fashion.  Therefore, a vehicular link model should consider the
   frequent partitioning and merging of VANETs due to vehicle mobility.

   An IPv6 prefix can be used in a multi-link subnet as an RSU's fixed extended
   subnet.  IPv6 Stateless Address Autoconfiguration (SLAAC) needs to be
   performed even in the multiple links where all of the links are
   configured with the same subnet prefix [RFC4861][RFC4862].  Thus, a
   vehicular link model can consider a multi-hop V2V (or V2I) over a
   multi-link subnet in a vehicular network having multiple VANETs and
   RSUs, as shown in Figure 1.  For example, in this figure, vehicles
   (i.e., Vehicle1, Vehicle2, and Vehicle3) in Subnet1 and Subnet2
   having RSU1 and RSU2, respectively, construct a multi-link subnet
   with VANETs and RSUs.  Vehicle1 and Vehicle3 can also communicate
   with each other via V2I communication.

                                                    +-----------------+
                           (*)<........>(*)  +----->| Vehicular Cloud |
          2001:DB8:1:1::/64 |            |   |      +-----------------+
   +------------------------------+  +---------------------------------+
   |                        v     |  |   v   v                         |
   | +-------+ +------+ +-------+ |  | +-------+ +------+ +-------+    |
   | | Host1 | | DNS1 | |Router1| |  | |Router3| | DNS2 | | 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        |
   +------------------------------+  +---------------------------------+ either multi-hop V2V or multi-hop V2I2V.  When
   two vehicles (e.g., Vehicle1 (Moving Network1)            RSU1 (Fixed Network1)

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

     Figure 2: Internetworking between Vehicle Network and RSU Network

   As shown Vehicle3 in Figure 2, 1) are connected
   in a VANET, it will be more efficient for them to communicate with
   each other via VANET rather than RSUs.  On the vehicle's moving network other hand, when two
   vehicles (e.g., Vehicle1 and the RSU's
   fixed network Vehicle3) are self-contained networks having multiple subnets and
   having an edge router for far away from the
   communication with another vehicle or
   RSU.  Internetworking between two internal networks via V2I
   communication requires an exchange of network prefix range in separate VANETs and under two different RSUs,
   they can communicate with each other
   parameters through a prefix discovery mechanism, such as ND-based
   prefix discovery [ID-Vehicular-ND].  For the ND-based prefix
   discovery, network prefixs and parameters should relay of RSUs via
   V2I2V.

   Therefore, IPv6 ND needs to 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 extended for an IP communication between a vehicle and efficient Vehicular
   Neighbor Discovey (VND) to support the concept of an RSU or between two
   neighboring vehicles, such as link layer, MAC layer, and IP layer
   information.  The link layer information includes wireless IPv6 link layer
   parameters, such as wireless media (e.g., IEEE 802.11-OCB and LTE-
   V2X) and
   corresponding to an IPv6 prefix even in a transmission power level.  The multi-link subnet
   consisting of multiple vehicles and RSUs [ID-Vehicular-ND].

5.1.2.  MAC layer information
   includes Address Pseudonym

   For the protection of drivers' privacy, the pseudonym of a MAC
   address of an external a vehicle's network interface for the
   internetworking should be used, with another vehicle or RSU.  The IP layer
   information includes the IP address and prefix
   help of an external network
   interface for the internetworking with another vehicle or RSU.

   Once which the network parameter discovery and prefix exchange operations
   have been performed, packets MAC address can be transmitted between changed periodically.  The
   pseudonym of a MAC address affects an IPv6 address based on the vehicle's
   moving network MAC
   address, and a transport-layer (e.g., TCP) session with an IPv6
   address pair.  However, the RSU's fixed network.  DNS services should be
   supported to enable name resolution pseudonym handling is not implemented and
   tested yet for hosts or servers residing
   either in applications on IP-based vehicular networking.

   In the vehicle's moving ETSI standards, for the sake of security and privacy, an ITS
   station (e.g., vehicle) can use pseudonyms for its network or interface
   identities (e.g., MAC address) and the RSU's fixed network.
   It is assumed that corresponding IPv6 addresses
   [Identity-Management].  Whenever the DNS names network interface identifier
   changes, the IPv6 address based on the network interface identifier
   should be updated, and the uniqueness of in-vehicle devices the address should be
   performed through the DAD procedure.  For vehicular networks with
   high-mobility, this DAD should be performed efficiently with minimum
   overhead.

   For the continuity of an end-to-end (E2E) transport-layer (e.g., TCP,
   UDP, and their
   service names are registered into a DNS server in SCTP) session, with a vehicle or an
   RSU, as shown in Figure 2.  For service discovery, those DNS names mobility management scheme (e.g.,
   MIPv6 and service names PMIPv6), the new IP address for the transport-layer session
   can be advertised notified to neighboring vehicles through
   either DNS-based service discovery mechanisms
   [RFC6762][RFC6763][ID-DNSNA] an appropriate end point, and ND-based service discovery
   [ID-Vehicular-ND].  For the ND-based service discovery, service names packets of the
   session should be registered into a vehicle's router and an RSU router forwarded to their destinations with
   an external the changed
   network interface identifier and IPv6 address.  This mobiliy
   management overhead for pseudonyms should be minimized for efficient
   operations in advance.  For this service
   discovery, each vehicular networks having lots of vehicles.

5.1.3.  Prefix Dissemination/Exchange

   A vehicle and each an RSU should can have its dedicated DNS
   server within its their internal network, respectively, as shown in
   Figure 2.

   Figure 2 shows internetworking between the vehicle's moving network and Figure 3.  In this case, nodes in within the RSU's fixed network.  There exists an internal network
   (Moving Network1) inside Vehicle1.  Vehicle1 has the DNS Server
   (DNS1), the
   networks of two hosts (Host1 and Host2), vehicular nodes (e.g., vehicle and RSU) want to
   communicate with each other.  For this communication on the wireless
   link, the two routers (Router1
   and Router2).  There exists another internal network (Fixed Network1)
   inside RSU1.  RSU1 prefix dissemination or exchange is required.  It
   is assumed that a vehicular node has the DNS Server (DNS2), one host (Host3), the
   two routers (Router3 an external network interface
   and Router4), its internal network, as shown in Figure 2 and Figure 3.  The
   vehicular ND (VND) [ID-Vehicular-ND] can support the collection communication
   between the internal-network nodes (e.g., an in-vehicle device in a
   vehicle and a server in an RSU) of servers
   (Server1 to ServerN) vehicular nodes with a vehicular
   prefix information option.  Thus, this ND extension for various services routing
   functionality can reduce control traffic for routing in the road networks, such
   as the emergency notification and navigation.  Vehicle1's Router1
   (called mobile router) vehicular
   networks without a vehicular ad hoc routing protocol (e.g., AODV
   [RFC3561] and RSU1's Router3 (called fixed router) use
   2001:DB8:1:1::/64 for an external link OLSRv2 [RFC7181]).

5.1.4.  Routing

   For multihop V2V communications in a VANET (or a multi-link subnet),
   a vehicular ad hoc routing protocol (e.g., DSRC) for I2V
   networking.

4.2.1.2.  V2V-based Internetworking

   This section discusses the internetworking between AODV and OLSRv2) may be
   required to support both unicast and multicast in the moving
   networks links of two neighboring vehicles via V2V communication.

                           (*)<..........>(*)
          2001:DB8:1:1::/64 |              |
   +------------------------------+  +------------------------------+
   |                        v     |  |     v                        |
   | +-------+ +------+ +-------+ |  | +-------+ +------+ +-------+ |
   | | Host1 | | DNS1 | |Router1| |  | |Router5| | DNS3 | | 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

   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 (DNS1), 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 (DNS3), 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.

4.2.2.  Latency

   The communication delay (i.e., latency) between two vehicles should
   be bounded to a certain threshold (e.g., 500 ms) for collision-
   avoidance message exchange [CASD].  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 yet.  Thus, the feasibility of IP-based safety applications
   is not tested yet in the real world.

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.  This sybil
   attack should be prevented through the cooperation between good
   vehicles and RSUs.  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, the pseudonym of a MAC
   address of a vehicle's network interface should be used, with the
   help of which the MAC address can be changed periodically.  The
   pseudonym of a MAC address affects an IPv6 address based on the MAC
   address, and a transport-layer (e.g., TCP) session with an IPv6
   address pair.  However, 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 (e.g., from 1 sec to 0.5 sec) for the NA
   messages to reach the neighboring vehicles promptly.  Also, as
   vehicle density is higher, the NA interval should increase (e.g.,
   from 0.5 sec to 1 sec) 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 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 result, a new vehicular link model
   is required for a dynamically changing 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 into a multi-link subnet with an
   extended subnet concept [RFC6775].  Also, note that IPv6 Stateless
   Address Autoconfiguration (SLAAC) 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 vehicular link model needs to consider a multi-hop V2V (or V2I)
   over a multi-link subnet as shown in Figure 1.  In this figure,
   vehicles in Subnet1 having RSU1 and RSU2 construct a multi-link
   subnet called Subnet1 with VANETs and RSUs.  Vehicle1 and Vehicle3
   can communicate with each other via multi-hop V2V or multi-hop V2I2V.
   When two vehicles (e.g., Vehicle1 and Vehicle3 in Figure 1) are
   connected in a VANET, they can communicate with each other via VANET
   rather than RSUs.  On the other hand, when two vehicles (e.g.,
   Vehicle1 and Vehicle3) are far away from the communication range in
   separate VANETs and under two different RSUs, they can communicate
   with each other through the relay of RSUs via V2I2V.

   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, and the uniqueness of the address should be
   performed through the DAD procedure.  For vehicular networks with
   high-mobility, this DAD should be performed efficiently with minimum
   overhead.

   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 address for the transport-layer session
   can be notified to an appropriate end point, and the packets of the
   session should be forwarded to their destinations with the changed
   network interface identifier and IPv6 address.  This mobiliy
   management overhead for pseudonyms should be minimized for efficient
   operations in vehicular networks having lots of vehicles.

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, as shown in Figure 2 and Figure 3.  The
   vehicular ND (VND) [ID-Vehicular-ND] can support 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 with a vehicular
   prefix information option.  Thus, this ND extension for routing
   functionality can reduce control traffic for routing in vehicular
   networks without a vehicular ad hoc routing protocol (e.g., AODV
   [RFC3561] and OLSRv2 [RFC7181]).

5.1.4.  Routing

   For multihop V2V communications in a multi-link subnet (as a
   connected VANET), a vehicular ad hoc routing protocol (e.g., AODV and
   OLSRv2) may be required to support both unicast and multicast in the
   links of the subnet with the same IPv6 prefix.  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].  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 in a multi-link
   subnet to prevent or reduce IPv6 address conflicts in such a subnet
   by using a multi-hop DAD optimization [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.  The GPS receiver may not provide vehicles with
   accurate location information in adverse, local environments such as
   building area and tunnel.  The location precision can be improved by
   the assistance from the RSUs or a cellular system with a 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.  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 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, 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.  Even though a vehicle moves
   into the wireless link under another RSU belonging to a different
   subnet, the RSU can proactively perform the DAD for the sake of the
   vehicle, reducing IPv6 control traffic overhead in the wireless link
   [ID-Vehicular-ND].  To prevent a hacker from impersonating RSUs as
   bogus RSUs, RSUs and MA should have secure channels via IPsec.

   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 along with the MA.  Thus, a
   moving vehicle can communicate with its corresponding vehicle in the
   vehicular network or a host/server in the Internet along its
   trajectory.

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
   addresses.

6.  Security Considerations

   This document discussed security and privacy for IP-based vehicular
   networking.

   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

   [Address-Assignment]
              Kato, T., Kadowaki, K., Koita, T., and K. Sato, "Routing
              and Address Assignment using Lane/Position Information in
              a Vehicular Ad-hoc Network", IEEE Asia-Pacific Services
              Computing Conference, December 2008.

   [Address-Autoconf]
              Fazio, M., Palazzi, C., Das, S., and M. Gerla, "Automatic
              IP Address Configuration in VANETs", ACM International
              Workshop on Vehicular Inter-Networking, September 2016.

   [Automotive-Sensing]
              Choi, J., Va, V., Gonzalez-Prelcic, N., Daniels, R., R.
              Bhat, C., and R. W. Heath, "Millimeter-Wave Vehicular
              Communication to Support Massive Automotive Sensing",
              IEEE Communications Magazine, December 2016.

   [Broadcast-Storm]
              Wisitpongphan, N., K. Tonguz, O., S. Parikh, J., Mudalige,
              P., Bai, F., and V. Sadekar, "Broadcast Storm Mitigation
              Techniques in Vehicular Ad Hoc Networks", IEEE Wireless
              Communications, December 2007.

   [CA-Cruise-Control]
              California Partners for Advanced Transportation Technology
              (PATH), "Cooperative Adaptive Cruise Control", [Online]
              Available:
              http://www.path.berkeley.edu/research/automated-and-
              connected-vehicles/cooperative-adaptive-cruise-control,
              2017.

   [CASD]     Shen, Y., Jeong, J., Oh, T., and S. Son, "CASD: A
              Framework of Context-Awareness Safety Driving in Vehicular
              Networks", International Workshop on Device Centric Cloud
              (DC2), March 2016.

   [Cluster-Based-Routing]
              Abboud, K. and W. Zhuang, "Impact of Microscopic Vehicle
              Mobility on Cluster-Based Routing Overhead in VANETs",
              IEEE Transactions on Vehicular Technology, Vol. 64, No.
              12, December 2015.

   [DSRC]     ASTM International, "Standard Specification for
              Telecommunications and Information Exchange Between
              Roadside and Vehicle Systems - 5 GHz Band Dedicated Short
              Range Communications (DSRC) Medium Access Control (MAC)
              and Physical Layer (PHY) Specifications",
              ASTM E2213-03(2010), October 2010.

   [ETSI-GeoNetwork-IP]
              ETSI Technical Committee Intelligent Transport Systems,
              "Intelligent Transport Systems (ITS); Vehicular
              Communications; GeoNetworking; Part 6: Internet
              Integration; Sub-part 1: Transmission of IPv6 Packets over
              GeoNetworking Protocols", ETSI EN 302 636-6-1, October
              2013.

   [ETSI-GeoNetworking]
              ETSI Technical Committee Intelligent Transport Systems,
              "Intelligent Transport Systems (ITS); Vehicular
              Communications; GeoNetworking; Part 4: Geographical
              addressing and forwarding for point-to-point and point-to-
              multipoint communications; Sub-part 1: Media-Independent
              Functionality", ETSI EN 302 636-4-1, May 2014.

   [EU-2008-671-EC]
              European Union, "Commission Decision of 5 August 2008 on
              the Harmonised Use of Radio Spectrum in the 5875 - 5905
              MHz Frequency Band for Safety-related Applications of
              Intelligent Transport Systems (ITS)", EU 2008/671/EC,
              August 2008.

   [FirstNet]
              U.S. National Telecommunications and Information
              Administration (NTIA), "First Responder Network Authority
              (FirstNet)", [Online]
              Available: https://www.firstnet.gov/, 2012.

   [FirstNet-Report]
              First Responder Network Authority, "FY 2017: ANNUAL REPORT
              TO CONGRESS, Advancing Public Safety Broadband
              Communications", FirstNet FY 2017, December 2017.

   [Fuel-Efficient]
              van de Hoef, S., H. Johansson, K., and D. V. Dimarogonas,
              "Fuel-Efficient En Route Formation of Truck Platoons",
              IEEE Transactions on Intelligent Transportation Systems,
              January 2018.

   [GeoSAC]   Baldessari, R., Bernardos, C., and M. Calderon, "GeoSAC -
              Scalable Address Autoconfiguration for VANET Using
              Geographic Networking Concepts", IEEE International
              Symposium on Personal, Indoor and Mobile Radio
              Communications, September 2008.

   [H-DMM]    Nguyen, T. and C. Bonnet, "A Hybrid Centralized-
              Distributed Mobility Management for Supporting Highly
              Mobile Users", IEEE International Conference on
              Communications, June 2015.

   [H-NEMO]   Nguyen, T. and C. Bonnet, "A Hybrid Centralized-
              Distributed Mobility Management Architecture for Network
              Mobility", IEEE International Symposium on A World of
              Wireless, Mobile and Multimedia Networks, June 2015.

   [ID-DNSNA]
              Jeong, J., Ed., Lee, S., and J. Park, "DNS Name
              Autoconfiguration for Internet of Things Devices", draft-
              jeong-ipwave-iot-dns-autoconf-04 (work in progress),
              October 2018.

   [ID-Vehicular-ND]
              Jeong, J., Ed., Shen, Y., and Z. Xiang, "IPv6 Neighbor
              Discovery for IP-Based Vehicular Networks", draft-jeong-
              ipwave-vehicular-neighbor-discovery-06 (work in progress),
              March 2019.

   [Identity-Management]
              Wetterwald, M., Hrizi, F., and P. Cataldi, "Cross-layer
              Identities Management in ITS Stations", The 10th
              International Conference on ITS Telecommunications,
              November 2010.

   [IEEE-802.11-OCB]
              "Part 11: Wireless LAN Medium Access Control (MAC) and
              Physical Layer (PHY) Specifications", IEEE Std
              802.11-2016, December 2016.

   [IEEE-802.11p]
              "Part 11: Wireless LAN Medium Access Control (MAC) and
              Physical Layer (PHY) Specifications - Amendment 6:
              Wireless Access in Vehicular Environments", IEEE Std
              802.11p-2010, June 2010.

   [Intro-to-Algorithms]
              H. Cormen, T., E. Leiserson, C., L. Rivest, R., and C.
              Stein, "Introduction to Algorithms, 3rd ed.", The
              MIT Press, July 2009.

   [IP-Passing-Protocol]
              Chen, Y., Hsu, C., and W. Yi, "An IP Passing Protocol for
              Vehicular Ad Hoc Networks with Network Fragmentation",
              Elsevier Computers & Mathematics the
   subnet with Applications,
              January 2012.

   [IPv6-over-802.11-OCB]
              Petrescu, A., Benamar, N., Haerri, J., Lee, J., and T.
              Ernst, "Transmission of IPv6 Packets over IEEE 802.11
              Networks operating in mode Outside the Context of a Basic
              Service Set (IPv6-over-80211-OCB)", draft-ietf-ipwave-
              ipv6-over-80211ocb-34 (work in progress), December 2018.

   [IPv6-WAVE]
              Baccelli, E., Clausen, T., and R. Wakikawa, "IPv6
              Operation for WAVE - Wireless Access in Vehicular
              Environments", IEEE Vehicular Networking Conference,
              December 2010.

   [ISO-ITS-IPv6]
              ISO/TC 204, "Intelligent Transport Systems -
              Communications Access for Land Mobiles (CALM) - IPv6
              Networking", ISO 21210:2012, June 2012.

   [Joint-IP-Networking]
              Petrescu, A., Boc, M., and C. Ibars, "Joint IP Networking
              and Radio Architecture for Vehicular Networks",
              11th International Conference on ITS Telecommunications,
              August 2011.

   [LAGAD]    Abrougui, K., Boukerche, A., and R. Pazzi, "Location-Aided
              Gateway Advertisement and Discovery Protocol for VANets",
              IEEE Transactions on Vehicular Technology, Vol. 59, No. 8,
              October 2010.

   [Multicast-802]
              Perkins, C., Stanley, D., Kumari, W., and JC. Zuniga,
              "Multicast Considerations over IEEE 802 Wireless Media",
              draft-perkins-intarea-multicast-ieee802-03 (work in
              progress), July 2017.

   [Multicast-Alert]
              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.

   [NEMO-LMS]
              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.

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

   [PMIP-NEMO-Analysis]
              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.

   [RFC3561]  Perkins, C., Belding-Royer, E., same IPv6 prefix.  However, it will be costly to run
   both vehicular ND and S. Das, "Ad a vehicular ad hoc On-
              Demand Distance Vector (AODV) Routing", RFC 3561, July
              2003.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", RFC 4086, June
              2005.

   [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.

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.

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

   [RFC5944]  Perkins, C., Ed., "IP Mobility Support terms of
   control traffic overhead.  As a feasible approach, Vehicular ND can
   be extended to accommodate routing functionality with a prefix
   discovery option.  In this case, there is no need to run a separate
   vehicular ad hoc routing protocol in IPv4, Revised",
              RFC 5944, November 2010.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support VANETs.  The ND extension can
   allow vehicles to exchange their prefixes 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 a multihop fashion
   [ID-Vehicular-ND].  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 needs to be supported in a vehicular
   network having multiple VANETs (or a multi-link subnet) to prevent or
   reduce IPv6 over Low-Power
              Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
              November 2012.

   [RFC7181]  Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
              "The Optimized Link State Routing Protocol Version 2",
              RFC 7181, April 2014.

   [RFC7333]  Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements address conflicts in such a subnet.  A feasible approach
   is to use a multi-hop DAD optimization for Distributed the efficient vehicular-
   network-wide DAD [RFC6775][RFC8505].

5.2.  Mobility Management",
              RFC 7333, August 2014.

   [RFC7429]  Liu, D., Zuniga, JC., Seite, P., Chan, H., Management

   The seamless connectivity and CJ.
              Bernardos, "Distributed Mobility Management: Current
              Practices timely data exchange between two end
   points requires an efficient mobility management including location
   management and Gap Analysis", RFC 7429, January 2015.

   [RFC8200]  Deering, S. handover.  Most of vehicles are equipped with a GPS
   receiver as part of a dedicated navigation system or a corresponding
   smartphone App.  The GPS receiver may not provide vehicles with
   accurate location information in adverse, local environments such as
   building area and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 8200, July 2017.

   [SAINT]    Jeong, J., Jeong, H., Lee, E., Oh, T., tunnel.  The location precision can be improved by
   the assistance from the RSUs or a cellular system with a GPS receiver
   for location information.

   With a GPS navigator, an efficient mobility management will be
   possible by vehicles periodically reporting their current position
   and D. Du, "SAINT:
              Self-Adaptive Interactive Navigation Tool trajectory (i.e., navigation path) to the vehicular
   infrastructure (having RSUs and an MA in TCC) [ID-Vehicular-MM].
   This vehicular infrastructure can predict the future positions of the
   vehicles with their mobility information (i.e., the current position,
   speed, direction, and trajectory) for Cloud-Based
              Vehicular Traffic Optimization", IEEE Transactions on
              Vehicular Technology, Vol. 65, No. 6, June 2016.

   [SAINTplus]
              Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., 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.

   With the prediction of the vehicle mobility, the vehicular
   infrastructure needs to support RSUs to perform efficient DAD, data
   packet routing, horizontal handover (i.e., handover in wireless links
   using a homogeneous radio technology), and D.
              Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+ vertical handover (i.e.,
   handover in wireless links using heterogeneous radio technologies) in
   a proactive manner [ID-Vehicular-MM].  For example, when a vehicle is
   moving into the wireless link under another RSU belonging to a
   different subnet, the RSU can proactively perform the DAD for Emergency Service Delivery Optimization",
              IEEE Transactions on Intelligent Transportation Systems,
              June 2017.

   [SANA]     Hwang, T. the
   sake of the vehicle, reducing IPv6 control traffic overhead in the
   wireless link.  To prevent a hacker from impersonating RSUs as bogus
   RSUs, RSUs and MA in the vehicular infrastructure need to have secure
   channels via IPsec.

   Therefore, with a proactive handover and J. Jeong, "SANA: Safety-Aware Navigation
              Application for Pedestrian Protection a multihop DAD in Vehicular
              Networks", Springer Lecture Notes vehicular
   networks, RSUs needs to efficiently forward data packets from the
   wired network (or the wireless network) to a moving destination
   vehicle along its trajectory.  As a result, a moving vehicle can
   communicate with its corresponding vehicle 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.

   [Securing-VCOMM]
              Fernandez, P., Santa, J., Bernal, F., and A. Skarmeta,
              "Securing Vehicular IPv6 Communications",
              IEEE Transactions on Dependable the vehicular network
   or a host/server in the Internet along its trajectory.

5.3.  Security and Secure Computing,
              January 2016.

   [TR-22.886-3GPP]
              3GPP, "Study on Enhancement Privacy

   Strong security measures shall protect vehicles roaming in road
   networks from the attacks of 3GPP Support for 5G V2X
              Services", 3GPP TS 22.886, June 2018.

   [Truck-Platooning]
              California Partners for Advanced Transportation Technology
              (PATH), "Automated Truck Platooning", [Online] Available:
              http://www.path.berkeley.edu/research/automated-and-
              connected-vehicles/truck-platooning, 2017.

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

   [VANET-Geo-Routing]
              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.

   [VIP-WAVE]
              Cespedes, S., Lu, N., 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 X. Shen, "VIP-WAVE: On 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.  This sybil
   attack should be prevented through the
              Feasibility of IP Communications in 802.11p Vehicular
              Networks", IEEE Transactions on Intelligent Transportation
              Systems, vol. 14, no. 1, March 2013.

   [VMaSC-LTE]
              Ucar, S., Ergen, S., and O. Ozkasap, "Multihop-Cluster-
              Based IEEE 802.11p cooperation between good
   vehicles and LTE Hybrid Architecture for VANET
              Safety Message Dissemination", IEEE Transactions RSUs.  Applications on
              Vehicular Technology, April 2016.

   [VNET-AAA]
              Moustafa, H., Bourdon, G., and Y. Gourhant, "Providing
              Authentication IP-based vehicular networking,
   which are resilient to such a sybil attack, are not developed and Access Control in Vehicular Network
              Environment", IFIP TC-11 International Information
   tested yet.

   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.

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

   [WAVE-1609.2]
              IEEE 1609 Working Group, "IEEE Standard for Wireless
              Access privacy are paramount in Vehicular Environments - Security Services for
              Applications the V2I, V2V, and Management Messages", IEEE Std
              1609.2-2016, March 2016.

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

   [WAVE-1609.4]
              IEEE 1609 Working Group, "IEEE Standard for Wireless
              Access V2X
   networking 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 vehicular networks.  Only authorized vehicles should be
   allowed to IPWAVE WG: (i) vehicle
   identity management; (ii) multihop V2X; (iii) multicast; (iv) DNS
   naming services use vehicular networking.  Also, in-vehicle devices and service discovery; (v) IPv6 over cellular
   networks.

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
   mobile devices in a vehicle need to communicate with
   multiple indenties, 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
   as to
   efficiently authenticate a globally unique vehicle identifier.

   To support the seamless connectivity over the multiple identities, or a
   cross-layer network architecture is required with vertical handover
   functionality [Identity-Management]. 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 AAA service RSU should be
   established, as shown in Figure 2.  Also, for
   multiple identities secure V2V
   communication, a secure channel between a mobile router in a vehicle
   and a mobile router in another vehicle should be provided to vehicles established, as
   shown in Figure 3.

   To prevent an efficient
   way adversary from tracking a vehicle with its MAC address
   or IPv6 address, MAC address pseudonym should be provided to allow horizontal handover as well as vertical handover; note the
   vehicle; that AAA stands 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
   addresses.

6.  Security Considerations

   This document discussed security and privacy for Authentication, Authorization, IP-based vehicular
   networking.

   The security and Accounting.

A.2.  Multihop V2X

   Multihop packet forwarding among vehicles privacy for key components in 802.11-OCB mode shows an
   unfavorable performance due IP-based vehicular
   networking, such as neighbor discovery and mobility management, need
   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 analyzed in a
   connected VANET or an RSU depth.

7.  Informative References

   [Automotive-Sensing]
              Choi, J., Va, V., Gonzalez-Prelcic, N., Daniels, R., R.
              Bhat, C., and R. W. Heath, "Millimeter-Wave Vehicular
              Communication to Support Massive Automotive Sensing",
              IEEE Communications Magazine, December 2016.

   [CA-Cruise-Control]
              California Partners for Advanced Transportation Technology
              (PATH), "Cooperative Adaptive Cruise Control", [Online]
              Available:
              http://www.path.berkeley.edu/research/automated-and-
              connected-vehicles/cooperative-adaptive-cruise-control,
              2017.

   [CASD]     Shen, Y., Jeong, J., Oh, T., and S. Son, "CASD: A
              Framework of Context-Awareness Safety Driving in an intersection area, where the cluster
   head can work as a coodinator Vehicular
              Networks", International Workshop on Device Centric Cloud
              (DC2), March 2016.

   [DSRC]     ASTM International, "Standard Specification for
              Telecommunications and Information Exchange Between
              Roadside and Vehicle Systems - 5 GHz Band Dedicated Short
              Range Communications (DSRC) Medium Access Control (MAC)
              and Physical Layer (PHY) Specifications",
              ASTM E2213-03(2010), October 2010.

   [ETSI-GeoNetwork-IP]
              ETSI Technical Committee Intelligent Transport Systems,
              "Intelligent Transport Systems (ITS); Vehicular
              Communications; GeoNetworking; Part 6: Internet
              Integration; Sub-part 1: Transmission of IPv6 Packets over
              GeoNetworking Protocols", ETSI EN 302 636-6-1, October
              2013.

   [ETSI-GeoNetworking]
              ETSI Technical Committee Intelligent Transport Systems,
              "Intelligent Transport Systems (ITS); Vehicular
              Communications; GeoNetworking; Part 4: Geographical
              addressing and forwarding for point-to-point and point-to-
              multipoint communications; Sub-part 1: Media-Independent
              Functionality", ETSI EN 302 636-4-1, May 2014.

   [EU-2008-671-EC]
              European Union, "Commission Decision of 5 August 2008 on
              the access to wireless channels.

A.3.  Multicast

   IP multicast Harmonised Use of Radio Spectrum in vehicular network environments is especially useful the 5875 - 5905
              MHz Frequency Band for various services.  For instance, an automobile manufacturer can
   multicast a particular group/class/type Safety-related Applications 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
              Intelligent Transport Systems (ITS)", EU 2008/671/EC,
              August 2008.

   [FirstNet]
              U.S. National Telecommunications and
   functions based Information
              Administration (NTIA), "First Responder Network Authority
              (FirstNet)", [Online]
              Available: https://www.firstnet.gov/, 2012.

   [FirstNet-Report]
              First Responder Network Authority, "FY 2017: ANNUAL REPORT
              TO CONGRESS, Advancing Public Safety Broadband
              Communications", FirstNet FY 2017, December 2017.

   [Fuel-Efficient]
              van de Hoef, S., H. Johansson, K., and D. V. Dimarogonas,
              "Fuel-Efficient En Route Formation of Truck Platoons",
              IEEE Transactions on IPv6 use multicast Intelligent Transportation Systems,
              January 2018.

   [ID-Vehicular-MM]
              Jeong, J., Ed., Shen, Y., and Z. Xiang, "Vehicular
              Mobility Management for control-plane messages,
   such as IP-Based Vehicular Networks",
              draft-jeong-ipwave-vehicular-mobility-management-00 (work
              in progress), March 2019.

   [ID-Vehicular-ND]
              Jeong, J., Ed., Shen, Y., and Z. Xiang, "IPv6 Neighbor
              Discovery (ND) for IP-Based Vehicular Networks", draft-jeong-
              ipwave-vehicular-neighbor-discovery-06 (work in progress),
              March 2019.

   [Identity-Management]
              Wetterwald, M., Hrizi, F., and P. Cataldi, "Cross-layer
              Identities Management in ITS Stations", The 10th
              International Conference on ITS Telecommunications,
              November 2010.

   [IEEE-802.11-OCB]
              "Part 11: Wireless LAN Medium Access Control (MAC) and
              Physical Layer (PHY) Specifications", IEEE Std
              802.11-2016, December 2016.

   [IEEE-802.11p]
              "Part 11: Wireless LAN Medium Access Control (MAC) and
              Physical Layer (PHY) Specifications - Amendment 6:
              Wireless Access in Vehicular Environments", IEEE Std
              802.11p-2010, June 2010.

   [Intro-to-Algorithms]
              H. Cormen, T., E. Leiserson, C., L. Rivest, R., and Service Discovery,
   [Multicast-802] describes that the ND process may fail due C.
              Stein, "Introduction to
   unreliable wireless link, causing failure Algorithms, 3rd ed.", The
              MIT Press, July 2009.

   [IPv6-over-802.11-OCB]
              Benamar, N., Haerri, J., Lee, J., and T. Ernst,
              "Transmission of the DAD process.  Also,
   the Router Advertisement messages can be lost IPv6 Packets over IEEE 802.11 Networks
              operating in multicasting.

A.4.  DNS Naming Services and Service Discovery

   When two vehicular nodes communicate with each other using mode Outside the DNS
   name Context of the partner node, DNS naming service (i.e., DNS name
   resolution) is required.  As shown a Basic Service
              Set (IPv6-over-80211-OCB)", draft-ietf-ipwave-ipv6-over-
              80211ocb-45 (work in Figure 2 progress), April 2019.

   [ISO-ITS-IPv6]
              ISO/TC 204, "Intelligent Transport Systems -
              Communications Access for Land Mobiles (CALM) - IPv6
              Networking", ISO 21210:2012, June 2012.

   [RFC3561]  Perkins, C., Belding-Royer, E., and Figure 3, a DNS
   server within an internal network can perform such DNS name
   resolution S. Das, "Ad hoc On-
              Demand Distance Vector (AODV) Routing", RFC 3561, July
              2003.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for the sake of other vehicular nodes.

   A service discovery service is required Security", RFC 4086, June
              2005.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for an application 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 a
   vehicular node to search
              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.

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for another application or server Proxy
              Mobile IPv6", RFC 5844, May 2010.

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

   [RFC5944]  Perkins, C., Ed., "IP Mobility Support in either the same internal network or
   the other internal network.  In V2I or V2V networking, as shown IPv4, Revised",
              RFC 5944, November 2010.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in
   Figure 2 IPv6", RFC 6275, July 2011.

   [RFC6775]  Shelby, Z., Chakrabarti, S., Nordmark, E., and Figure 3, such a service discovery service can be
   provided by either DNS-based Service C. Bormann,
              "Neighbor Discovery (DNS-SD) [RFC6763]
   with mDNS [RFC6762] or the vehicular ND with a new option Optimization for service
   discovery [ID-Vehicular-ND].

A.5. IPv6 over Cellular Low-Power
              Wireless Personal Area Networks

   Recently, 3GPP has announced a set of new technical specifications,
   such as Release 14 (3GPP-R14) [TS-23.285-3GPP], which proposes an
   architecture enhancements for V2X services using the modified
   sidelink interface that originally is designed for the LTE-Device-to-
   Device (D2D) communications.  3GPP-R14 specifies that the V2X
   services only support IPv6 implementation.  3GPP is also
   investigating (6LoWPANs)", RFC 6775,
              November 2012.

   [RFC7181]  Clausen, T., Dearlove, C., Jacquet, P., and discussing the evolved V2X services in the next
   generation cellular networks, i.e., 5G new radio (5G-NR), U. Herberg,
              "The Optimized Link State Routing Protocol Version 2",
              RFC 7181, April 2014.

   [RFC7333]  Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for
   advanced V2X communications Distributed Mobility Management",
              RFC 7333, August 2014.

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

   [RFC8200]  Deering, S. and LTE for safety
   message dissemination.  Most of the research considers a short
   message service R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 8200, July 2017.

   [RFC8505]  Thubert, P., Nordmark, E., Chakrabarti, S., and C.
              Perkins, "Registration Extensions for safety instead of IP datagram forwarding.  In
   other C-V2X research, the standard IPv6 is assumed.

   The 3GPP technical specification of [TS-23.285-3GPP] states that both
   IP based over Low-Power
              Wireless Personal Area Network (6LoWPAN) Neighbor
              Discovery", RFC 8505, November 2018.

   [SAINT]    Jeong, J., Jeong, H., Lee, E., Oh, T., and non-IP based V2X messages are supported, 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.

   [SAINTplus]
              Shen, Y., Lee, J., Jeong, H., Jeong, J., Lee, E., and only IPv6
   is supported D.
              Du, "SAINT+: Self-Adaptive Interactive Navigation Tool+
              for IP based messages.  Moreover, [TS-23.285-3GPP]
   instructs that a UE autoconfigures a link-local IPv6 address by
   following SLAAC 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 [RFC4862], but without sending Neighbor
   Solicitation Vehicular
              Networks", Springer Lecture Notes in Computer Science
              (LNCS), Vol. 9502, December 2015.

   [SDN-DMM]  Nguyen, T., Bonnet, C., and Neighbor Advertisement messages J. Harri, "SDN-based
              Distributed Mobility Management 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 Networks",
              IEEE Wireless Communications and efficient
   communication infrastructure Networking Conference,
              April 2016.

   [Truck-Platooning]
              California Partners for Advanced Transportation Technology
              (PATH), "Automated Truck Platooning", [Online] Available:
              http://www.path.berkeley.edu/research/automated-and-
              connected-vehicles/truck-platooning, 2017.

   [TS-23.285-3GPP]
              3GPP, "Architecture Enhancements for road networks.  Correspondingly,
   enhanced V2X (eV2X)-based services can be supported by 5G systems.
   The Services", 3GPP Technical Report of [TR-22.886-3GPP] is studying new use
   cases
              TS 23.285, June 2018.

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

   [WAVE-1609.0]
              IEEE 1609 Working Group, "IEEE Guide for V2X (including
   V2V and V2I) using 5G Wireless Access
              in both infrastructure mode Vehicular Environments (WAVE) - Architecture", IEEE Std
              1609.0-2013, March 2014.

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

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

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

Appendix B. A.  Changes from draft-ietf-ipwave-vehicular-networking-07 draft-ietf-ipwave-vehicular-networking-08

   The following changes are made from draft-ietf-ipwave-vehicular-
   networking-07:
   networking-08:

   o  This version is revised based on the comments from Charlie Perkins
      and Sri Gundavelli.

   o  In Section 4.1, the existing protocols relevant to IP vehicular
      networking are summarized and analyzed with pros and cons.  This
      subsection addresses version focuses on the requirements for IP vehicular networking.

   o  In Figure 1, a vehicular network architecture is modified to
      clarify a multi-link subnet consisting of problem statement about IP-based
      vehicular wireless
      links, networking, such as IPv6 neighbor discovery, mobility
      management, and to provide efficient vehicular communications for V2I security &
      V2V to vehicles whose wireless interface is configured with a
      global IP address. privacy.

Appendix C. B.  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 MSIT (Ministry of Science and ICT (MSIT)
   (NRF-2013K1A1A2A02078326) and by
   ICT), Korea, under the DGIST R&D Program of ITRC (Information Technology Research Center)
   support program (IITP-2019-2017-0-01633) supervised by the MSIT
   (18-EE-01). IITP
   (Institute for Information & communications Technology Promotion).

   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. C.  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).
   Telekom), and Pascal Thubert (Cisco).  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
   Morocco

   Phone: +212 6 70 83 22 36
   EMail: benamar73@gmail.com
   Sandra Cespedes
   NIC Chile Research Labs
   Universidad de Chile
   Av.  Blanco Encalada 1975
   Santiago
   Chile

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

   Jerome Haerri
   Communication Systems Department
   EURECOM
   Sophia-Antipolis
   France

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

   Dapeng Liu
   Alibaba
   Beijing, Beijing 100022
   China

   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
   USA

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

   Charles E.  Perkins
   Futurewei Inc.
   2330 Central Expressway
   Santa Clara, CA 95050
   USA
   Phone: +1 408 330 4586
   EMail: charliep@computer.org

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

   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
   FBConsulting
   21, Route de Luxembourg
   Wasserbillig, Luxembourg L-6633
   Luxembourg

   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