Internet DRAFT - draft-jeong-ipwave-vehicular-neighbor-discovery
draft-jeong-ipwave-vehicular-neighbor-discovery
IPWAVE Working Group J. Jeong, Ed.
Internet-Draft Y. Shen
Intended status: Standards Track Sungkyunkwan University
Expires: 11 August 2024 S. Cespedes
NIC Chile Research Labs
8 February 2024
Vehicular Neighbor Discovery for IP-Based Vehicular Networks
draft-jeong-ipwave-vehicular-neighbor-discovery-17
Abstract
This document specifies a Vehicular Neighbor Discovery (VND) as an
extension of IPv6 Neighbor Discovery (ND) for IP-based vehicular
networks. An optimized Address Registration and a multihop Duplicate
Address Detection (DAD) mechanism are performed for having operation
efficiency and also saving both wireless bandwidth and vehicle
energy. In addition, three new ND options for prefix discovery,
service discovery, and mobility information report are defined to
announce the network prefixes and services inside a vehicle (i.e., a
vehicle's internal network).
Status of This Memo
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This Internet-Draft will expire on 11 August 2024.
Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Link Model . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. ND Optimization . . . . . . . . . . . . . . . . . . . . . 5
4.3. Design Goals . . . . . . . . . . . . . . . . . . . . . . 6
5. Vehicular Network Architecture . . . . . . . . . . . . . . . 6
6. ND Extension for Prefix and Service Discovery . . . . . . . . 8
6.1. Vehicular Prefix Information Option . . . . . . . . . . . 8
6.2. Vehicular Service Information Option . . . . . . . . . . 9
6.3. Vehicular Mobility Information Option . . . . . . . . . . 10
6.4. Vehicular Neighbor Discovery . . . . . . . . . . . . . . 11
6.5. Message Exchange Procedure for V2I Networking . . . . . . 12
7. Address Registration and Duplicate Address Detection . . . . 13
7.1. Address Autoconfiguration . . . . . . . . . . . . . . . . 14
7.2. Address Registration . . . . . . . . . . . . . . . . . . 14
7.3. Multihop Duplicate Address Detection . . . . . . . . . . 15
7.3.1. DAD without Intermediate Vehicle . . . . . . . . . . 15
7.3.2. DAD with one Intermediate Vehicle . . . . . . . . . . 17
7.3.3. DAD with multiple Intermediate Vehicles . . . . . . . 18
7.4. Pseudonym Handling . . . . . . . . . . . . . . . . . . . 19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 22
Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 22
Appendix C. Changes from
draft-jeong-ipwave-vehicular-neighbor-discovery-16 . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
Vehicular Ad Hoc Networks (VANET) have been researched for
Intelligent Transportation System (ITS) such as driving safety,
efficient driving and entertainment. Considering the high-speed
mobility of vehicular network based on Dedicated Short-Range
Communications (DSRC) [DSRC-WAVE], IEEE has standardized IEEE 802.11p
[IEEE-802.11p] as a MAC protocol for vehicles in Wireless Access in
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Vehicular Environments (WAVE). IEEE 802.11p was renamed IEEE 802.11
Outside the Context of a Basic Service Set (OCB) [IEEE-802.11-OCB].
In addition, IEEE has also standardized a family standard suite of
WAVE as IEEE 1609. This IEEE 1609 standard suite is considered as a
key component for ITS. IEEE 1609 standards include IEEE 1609.0
[WAVE-1609.0], 1609.2 [WAVE-1609.2], 1609.3 [WAVE-1609.3], and 1609.4
[WAVE-1609.4], which provide a low-latency and alternative network
for vehicular communications. What is more, IP-based vehicular
networks specialized as IP Wireless Access in Vehicular Environments
(IPWAVE) [RFC9365] can enable many use cases over vehicle-to-vehicle
(V2V), vehicle-to-infrastructure (V2I), and vehicle-to-everything
(V2X) communications. IETF has standardized an IPv6 packet delivery
protocol over IEEE 802.11-OCB [RFC8691].
VANET features high mobility dynamics, asymmetric and lossy
connections, and moderate power constraint (e.g., electric cars and
unmanned aerial vehicles). Links among hosts and routers in VANET
can be considered as undetermined connectivities with constantly
changing neighbors described in [RFC5889]. IPv6 [RFC8200] is
selected as the network-layer protocol for Internet applications by
IEEE 1609.0 and 1609.3. However, the relative long-time Neighbor
Discovery (ND) process in IPv6 [RFC4861] is not suitable in VANET
scenarios.
To better support the interaction between vehicles or between
vehicles and Rode-Side Units (RSUs), this document specifies a
Vehicular Neighbor Discovery (VND) procedure as an extension of IPv6
ND for IP-based vehicular networks. VND provides vehicles with an
optimized Address Registration and a multihop Duplicate Address
Detection (DAD) mechanism. In addition, an efficient mobility
management scheme is specified to support efficient V2V, V2I, and V2X
communications. Detailed statements of the mobility management are
addressed in [I-D.jeong-ipwave-vehicular-mobility-management] .
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Terminology
This document uses the terminology described in [RFC4861], [RFC4862],
[RFC6775], and [RFC8691]. In addition, the following new terms are
defined as below:
* WAVE: Acronym for "Wireless Access in Vehicular Environments"
[WAVE-1609.0].
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* Mobility Anchor (MA): A node that maintains IP addresses and
mobility information of vehicles in a road network to support the
address autoconfiguration and mobility management of them. It has
end-to-end connections with RSUs under its control. It maintains
a DAD Table recording the IP addresses of vehicles moving within
the communication coverage of its RSUs.
* Vehicular Cloud: A cloud infrastructure for vehicular networks,
including compute nodes, storage nodes, and network nodes.
* 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 and has MAs
under its management.
4. Overview
This document proposes an optimized ND with a more adaptive structure
for vehicular networks compared to [RFC4861] by considering dynamic
vehicle mobility and overhead of control message traffic in wireless
environments. Furthermore, prefix and service discovery can be
implemented as part of the ND's process along with an efficient
Address Registration procedure and a DAD mechanism for moving
vehicles. This document specifies a set of behaviors between
vehicles and RSUs to accomplish these goals.
4.1. Link Model
There is a relationship between a link and a network prefix along
with reachability scopes, such as link-local and global scopes. The
legacy IPv6 ND protocol [RFC4861] has the following link model. All
IPv6 nodes in the same on-link subnet, which use the same subnet
prefix with the on-link bit set, are reachable with each other by
one-hop links. The symmetry of the connectivity among the nodes is
assumed, that is, bidirectional connectivity between two on-link
nodes. However, a link model in vehicular networks (called vehicular
link model) should consider the asymmetry of the connectivity that
unidirectional links can exist due to interference in wireless
channels and the different levels of transmission power employed by
wireless network interfaces.
The on-link subnet can be constructed by one link (as a basic service
set) or multiple links (as an extended service set) called a multi-
link subnet [RFC6775]. In this multi-link subnet, an all-node-
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multicasted packet is copied and related to other links by an ND
proxy. On the other hand, in vehicular networks having fast moving
vehicles, multiple links can share the same subnet prefix for
operation efficiency. For example, if two wireless links under two
adjacent RSUs are in the same subnet, a vehicle as an IPv6 host does
not need to reconfigure its IPv6 address during handover between
those RSUs. However, the packet relay by an RSU as an ND proxy is
not required because such a relay can cause a broadcast storm in the
extended subnet. Thus, in the multi-link subnet, all-node-
multicasting needs to be well-calibrated to either being confined to
multicasting in the current link or being disseminated to other links
in the same subnet.
In a connected multihop VANET, for efficient communication, vehicles
in the same link of an RSU can communicate directly with each other,
not through the serving RSU. This direct wireless communication is
similar to the direct wired communication in an on-link subnet using
Ethernet as a wired network. The vehicular link model needs to
accommodate both the ad-hoc communication between vehicles and
infrastructure communication between a vehicle and an RSU in an
efficient and flexible way. Therefore, the IPv6 ND should be
extended to accommodate the concept of a new IPv6 link model in
vehicular networks.
To support multi-link subnet, this specification employs the Shared-
Prefix model for prefix assignments. A Shared-Prefix model refers to
an addressing model where the prefix(es) are shared by more than one
node. In this document, we assume that in a specified subnet, all
interfaces of RSUs responding for prefix assignments to vehicles hold
the same prefix, which ensure vehicles obtain and maintain the same
prefix in this subnet scope.
4.2. ND Optimization
This document takes advantage of the optimized ND for Low-Power
Wireless Personal Area Network (6LoWPAN) [RFC6775] because vehicular
environments have common parts with 6LoWPAN, such as the reduction of
unnecessary wireless traffic by multicasting and the energy saving in
battery. Note that vehicles tend to be electric vehicles whose
energy source is from their battery.
In the optimized IPv6 ND for 6LoWPAN, the connections among nodes are
assumed to be asymmetric and unidirectional because of changing radio
environment and loss signal. The authors proposed an optimized IPv6
ND which greatly eliminates link-scope multicast to save energy by
constructing new options and a new scheme for address configurations.
Similarly, this document proposes an improved IPv6 ND by eliminating
many link-scope-multicast-based ND operations, such as DAD for IPv6
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Stateless Address Autoconfiguration (SLAAC) [RFC4862]. Thus, this
document suggests an extension of IPv6 ND as vehicular ND tailored
for vehicular networks along with new ND options (e.g., prefix
discovery, service discovery, and mobility information options).
4.3. Design Goals
The vehicular ND in this document has the following design goals:
* To perform prefix and service discovery through ND procedure;
* To implement host-initiated refresh of Router Advertisement (RA)
and remove the necessity for routers to use periodic or
unsolicited multicast RA to find hosts;
* To replace Neighbor Unreachable Detection(NUD) and create Neighbor
Cache Entries (NCE) for all registered vehicles in RSUs and MA by
appending Address Registration Option (ARO) in Neighbor
Solicitation (NS) and Neighbor Advertisement (NA) messages;
* To support a multihop DAD by conveying ND messages received from
vehicles to MA to eliminate multicast storms and save energy; and
* To support multihop communication for vehicles outside the
coverage of RSUs to communicate with the serving RSU via a relay
neighbor.
5. Vehicular Network Architecture
A vehicular network architecture for V2I and V2V is illustrated in
Figure 1. Three RSUs are deployed along roadsides and are connected
to an MA through wired links. There are two subnets such as Subnet1
and Subnet2. The wireless links of RSU1 and RSU2 belong to the same
subnet named Subnet1, but the wireless link of RSU3 belongs to
another subnet named Subnet2. Vehicle2 is wirelessly connected to
RSU1 while Vehicle3 and Vehicle4 are connected to RSU2 and RSU3,
respectively. Vehicles can directly communicate with each other
through V2V connection (e.g., Vehicle1 and Vehicle2) to share driving
information. In addition, vehicles not in the range of any RSU may
connect with RSU in multihop connection via relay vehicle (e.g.,
Vehicle1 can contact RSU1 via Vehicle2). Vehicles are assumed to
start the connection to an RSU when they entered the coverage of the
RSU.
This document recommends a multi-link subnet involving multiple RSUs
as shown in Figure 1. This recommendation aims at the reduction of
the frequency with which vehicles have to change their IP address
during handover between two adjacent RSUs. To construct this multi-
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link subnet, a Shared-Prefix model is proposed. That is, for RSUs in
the same subnet, the interfaces responsible for prefix assignment for
vehicles should hold the same prefix in their global address. This
also promises vehicles achieve the same prefix in this scope. When
they pass through RSUs in the same subnet, vehicles do not need to
perform the Address Registration and DAD again because they can use
their current IP address in the wireless coverage of the next RSU.
Moreover, this proposal accords with the assumption that nodes
belonging to the same IP prefix domain are able to communicate with
each other directly without the intervention of RSUs if they are
within the wireless communication range of each other. On the other
hand, if vehicles enter the wireless coverage of an RSU belonging to
another subnet with a different prefix, they repeat the Address
Registration and DAD procedure to update their IP address with the
new prefix.
In Figure 1, RSU1 and RSU2 are deployed in a multi-link subnet with
the same prefix address in their interfaces responding for connection
with vehicles. When vehicle2 leaves the coverage of RSU1 and enters
RSU2, it maintains its address configuration and ignores Address
Registration and DAD steps. If vehicle2 moves into the coverage of
RSU3, since RSU3 belongs to another subnet and holds a different
prefix from RSU1 and RSU2, so vehicle2 must do Address Registration
and DAD just as connecting to a new RSU. Note that vehicles and RSUs
have their internal networks including in-vehicle devices and
servers, respectively. The structures of the internal networks are
described in [RFC9365].
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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
<----> Wired Link <....> Wireless Link ===> Moving Direction
Figure 1: A Vehicular Network Architecture for V2I and V2V Networking
6. ND Extension for Prefix and Service Discovery
This section specifies an IPv6 ND extension for vehicle-to-vehicle
(V2V) or vehicle-to-infrastructure (V2I) networking. This section
also defines three new ND options for prefix discovery, service
discovery, and mobility information report: (i) Vehicular Prefix
Information (VPI) option, (ii) Vehicular Service Information (VSI)
option, and (iii) Vehicular Mobility Information (VMI) option. It
also describes the procedure of the ND protocol with those options.
6.1. Vehicular Prefix Information Option
The VPI option contains IPv6 prefix information in the internal
network. Figure 2 shows the format of the VPI option.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length | Distance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Prefix :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Vehicular Prefix Information (VPI) Option Format
Fields:
Type 8-bit identifier of the VPI option type as assigned
by the IANA: TBD
Length 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of
8 octets. The value is 3.
Prefix Length 8-bit unsigned integer. The number of leading bits
in the Prefix that are valid. The value ranges
from 0 to 128.
Distance 8-bit unsigned integer. The distance between the
subnet announcing this prefix and the subnet
corresponding to this prefix in terms of the number
of hops.
Reserved This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Prefix An IP address or a prefix of an IP address. The
Prefix Length field contains the number of valid
leading bits in the prefix. The bits in the prefix
after the prefix length are reserved and MUST be
initialized to zero by the sender and ignored by
the receiver.
6.2. Vehicular Service Information Option
The VSI option contains vehicular service information in the internal
network. Figure 3 shows the format of the VSI option.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | Reserved2 | Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Node Address :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Vehicular Service Information (VSI) Option Format
Fields:
Type 8-bit identifier of the VSI option type as assigned
by the IANA: TBD
Length 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of
8 octets. The value is 3.
Reserved1 This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Protocol 8-bit unsigned integer to indicate the upper-layer
protocol, such as transport-layer protocol (e.g.,
TCP, UDP, and SCTP).
Reserved2 This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Port Number 16-bit unsigned integer to indicate the port number
for this protocol.
Service Address
128-bit IPv6 address of a node providing this vehicular
service.
6.3. Vehicular Mobility Information Option
The VMI option contains one vehicular mobility information of a
vehicle or an RSU. Figure 4 shows the format of the VMI option.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Mobility Information :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Vehicular Mobility Information (VMI) Option Format
Fields:
Type 8-bit identifier of the VMI option type as assigned
by the IANA: TBD
Length 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of
8 octets. The value is 3.
Reserved1 This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Reserved2 This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Mobility Information
128-bit mobility information, such as position,
speed, acceleration/deceleration, and direction.
6.4. Vehicular Neighbor Discovery
Prefix discovery enables hosts (e.g., vehicles and in-vehicle
devices) to distinguish destinations on the same link from those only
reachable via RSUs. A vehicle (or its in-vehicle devices) can
directly communicate with on-link vehicles (or their in-vehicle
devices) without the relay of an RSU, but through V2V communications
along with VPI ND option. This VPI option contains IPv6 prefixes in
a vehicle's internal network.
Vehicles announce services in their internal networks to other
vehicles through an VSI ND option. The VSI option contains a list of
vehicular services in a vehicle's or an RSU's internal network.
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A vehicle periodically announces an NS message containing VPI and VSI
options with its prefixes and services in all-nodes multicast address
to reach all neighboring nodes. When it receives this NS message,
another neighboring node responds to this NS message by sending an NA
message containing the VPI and VSI options with its prefixes and
services via unicast towards the NS-originating node.
Therefore, prefix and service discovery can be achieved via ND
messages (e.g., NS and NA) by vehicular ND with VPI and VSI options.
This VND-based discovery eliminates an additional prefix and service
discovery scheme, such as DNS-based Service Discovery [RFC6763]
(e.g., Multicast DNS (mDNS) [RFC6762] and DNSNA
[I-D.jeong-ipwave-iot-dns-autoconf]), other than ND. That is,
vehicles and RSUs can rapidly discover the network prefixes and
services of the other party without any additional service discovery
protocol.
6.5. Message Exchange Procedure for V2I Networking
This subsection explains a message exchange procedure for VND in V2I
networking, where a vehicle communicates with its correspondent node
in the Internet via an RSU.
Figure 5 shows an example of message exchange procedure in V2I
networking. Detailed steps of the procedure are explained in
Section 7. The mobility management part is described in
[I-D.jeong-ipwave-vehicular-mobility-management].
Note that a vehicle could also perform the prefix and service
discovery simultaneously along with Address Registration procedure,
as shown in Figure 7.
This document specified that RSUs as routers do not transmit
periodical and unsolicited multicast RA messages including a prefix
for energy saving in vehicular networks. Vehicles as hosts
periodically initiate an RS message according to a time interval
(considering its position and an RSU's coverage). Since they have a
digital road map with the information of RSUs (e.g., position and
communication coverage), vehicles can know when they will go out of
the communication range of an RSU along with the signal strength
(e.g., Received Channel Power Indicator (RCPI) [VIP-WAVE]) from the
RSU. RSUs replies with a solicited RA in unicast only when they
receive an RS message.
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Vehicle RSU MA
| | |
|-RS with Mobility Info->| |
| [VMI] | |
| | |
| |-----------PBU--------->|
| | |
| | |
| |<----------PBA----------|
| | |
| | |
| |======Bi-Dir Tunnel=====|
| | |
| | |
|<----RA with prefix-----| |
| | |
| | |
| | |
|--NS with Address Reg-->| |
| [ARO+VPI+VSI] | |
| | |
| |---Forward NS for DAD-->|
| | |
| | |
| |<--NA with DAD result---|
| | [ARO+VPI+VSI] |
|<------Forward NA-------| |
| | |
Figure 5: Message Interaction for Vehicular Neighbor Discovery
7. Address Registration and Duplicate Address Detection
This section explains address configuration, consisting of IP Address
Autoconfiguration, Address Registration, and multihop DAD via V2I or
V2V.
This document recommends a new Address Registration and DAD scheme in
order to avoid multicast flooding and decrease link-scope multicast
for energy and wireless channel conservation on a large-scale
vehicular network. Host-initiated refresh of RA removes the
necessity for routers to use frequent and unsolicited multicast RAs
to accommodate hosts. This also enables the same IPv6 address
prefix(es) to be used across a subnet.
There are three scenarios feasible in Address Registration scheme:
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1. Vehicle enters the subnet for the first time or the current RSU
belongs to another subnet: Vehicles need to perform the Address
Registration and multihop DAD as described in the following
subsections.
2. Vehicle has already configured its IP addresses with prefix
obtained from the previous RSU, and the current RSU located in
the same subnet: This means RSUs have the same prefix and the
vehicle has no need to repeat the Address Registration and
multihop DAD.
3. Vehicle is not in the coverage of RSU but has a neighbor
registered in RSU: This document proposes a new V2V scenario for
vehicles which are currently not in the range of the RSU. If a
user vehicle failed to find an on-link RSU, it starts to look for
adjacent vehicle neighbors which can work as a relay neighbor to
share the prefix obtained from RSU and undertake DAD of the user
vehicle by forwarding DAD messages to RSU.
7.1. Address Autoconfiguration
A vehicle as an IPv6 host creates its link-local IPv6 address and
global IPv6 address as follows [RFC4862]. When they receive RS
messages from vehicles, RSUs send back RA messages containing prefix
information. The vehicle makes its global IPv6 addresses by
combining the prefix for its current link and its link-layer address.
The address autoconfiguration does not perform the legacy DAD as
defined in [RFC4862]. Instead, a new multihop DAD is performed in
Section 7.3.
7.2. Address Registration
After its IP tentative address autoconfiguration with the known
prefix from an RSU and its link-layer address, a vehicle starts to
register its IP address to the serving RSU along with multihop DAD.
Address Registration Option (ARO) is used in this step and its format
is defined in [RFC6775].
ARO is always host-initiated by vehicles. Information such as
registration time and registration status contained in ARO are
applied to indicate the registration duration and result. ARO will
also be forwarded to MA together with NS by RSUs.
An example message exchange procedure of Address Registration is
presented in Figure 6. Since Address Registration is performed
simultaneously with the multihop DAD, the specific procedure is
together described with the DAD mechanism in Section 7.3.
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Vehicle RSU
| |
| |
1. |----NS with Address Reg--->|
| [ARO] |
| |
| |
| |
2. |<---NA with Address Reg----|
| [ARO] |
Figure 6: Neighbor Discovery Address Registration
7.3. Multihop Duplicate Address Detection
Before it can exchange data, a node should determine whether its IP
address is already used by another node or not. In the legacy IPv6
ND, hosts multicast NS messages to all nodes in the same on-link
subnet for DAD. Instead of this, an optimized multihop DAD is
designed to eliminate multicast messages for energy-saving purpose.
For this multihop DAD, Neighbor Cache and DAD Table are maintained by
each RSU and an MA, respectively, for the duplicate address
inspection during the multihop DAD process. That is, each RSU makes
Neighbor Cache Entries (NCE) of all the on-link hosts in its Neighbor
Cache. Similarly, the MA stores all the NCEs reported by the RSUs in
its DAD Table.
With the multihop DAD, a vehicle can skip the multicast-based DAD in
its current wireless link whenever it enters the coverage of another
RSU in the same subset, leading to the reduction of traffic overhead
in vehicular wireless links.
For the multihop DAD, we take advantage of the procedure of [RFC6775]
but simplified the message flows by canceling the two new ICMPv6
message types such as Duplicate Address Request (DAR) and the
Duplicate Address Confirmation (DAC). Instead, NS and NA containing
ARO are directly forwarded between RSU and MA. This idea is raised
because DAR and DAC
7.3.1. DAD without Intermediate Vehicle
Figure 7 presents the procedure of Address Registration and multihop
DAD. The detailed steps are explained as follows.
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Vehicle RSU MA
| | |
| | |
1. |--NS with Address Reg-->| |
| [ARO+VPI+VSI] | |
| | |
2. | |----Forward NS--->|
| | |
| | |
3. | |<---Forward NA----|
| | |
| | |
4. |<--NA with Address Reg--| |
| [ARO+VPI+VSI] | |
Figure 7: Neighbor Discovery Address Registration with Multihop DAD
1. A vehicle sends an NS message to the current RSU in unicast,
containing the ARO to register its address.
2. The RSU receives the NS message, and then inspects its Neighbor
Cache to check whether it is duplicate or not. If there is no
duplicate NCE, a tentative NCE is created for this address, and
then the RSU forward the NS message containing the ARO to the MA
for the multihop DAD.
3. When the MA receives NS from an RSU, it checks whether the
register-requested address exists in its DAD Table or not. If an
entry with the same address exists in the DAD Table, which means
that the address is considered "Duplicate Address", then MA
returns a NA message containing the registration status in ARO to
notify the RSU of the address duplication. If no entry with the
same address exists in the DAD Table, which means that an entry
for the address is created, then MA replies a NA message to the
RSU to confirm the uniqueness of the register-requested address
to the RSU.
4. If the address duplication is notified by the MA, the RSU deletes
the tentative NCE, and forward NA with to the address-
registration vehicle to notify the registration failure.
Otherwise, the RSU changes the tentative NCE into a registered
NCE in its Neighbor Cache, and then forward NA to the vehicle to
notify the registration success.
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Thus, the multihop DAD is processed simultaneously with the Address
Registration. Note that the tentative address is not considered
assigned to the vehicle until the MA confirms the uniqueness of the
register-requested address in the multihop DAD.
7.3.2. DAD with one Intermediate Vehicle
If a vehicle failed to register a default router, it triggers
neighbor discovery to look for vehicle neighbors which can provide
relay service using multihop communication. In this specification,
we assumed vehicles would not emulate V2V communication and trigger
relay scenario only if Router Discovery(RD) failed.
User Vehicle Relay Vehicle RSU MA
| | | |
|------------------------| | |
| RD failed | | |
|------------------------| | |
| | | |
| | | |
|-----------NS---------->| | |
| | | |
|<--NA with Prefix Info--| | |
| | | |
| | | |
|--NS with Address Reg-->| | |
| [ARO+VPI+VSI] | | |
| |----- Forward NS ----->| |
| | | |
| | |-----------------|
| | | Same as Figure 9|
| | |-----------------|
| | | |
| |<--NA with Address Reg-| |
| | [ARO+VPI+VSI] | |
|<------ Forward NA -----| | |
| | | |
Figure 8: Address Registration and Multihop DAD via V2V Relay
Since vehicles have a digital road map with the information of RSUs
(e.g., position and communication coverage), they can determine if
they are available to serve as a relay vehicle. Only vehicles with
the ability to serve as temporary relays will take action when they
receive relay service requests. The user vehicle can process global
address configuration, Address Registration and DAD through its relay
vehicle before it enters the coverage of RSUs. See Figure 8.
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When a user vehicle failed to directly register to an RSU, it
initiates neighbor discovery to detect vehicle neighbors through V2V
communication. Vehicle sends NS messages to connect with neighbors
in range. If neighbor can provide relay service, it creates a NCE
for user vehicle, setting its own address as relay address, and sends
back NA with prefix information received from RSU.
To guarantee vehicles could find the nearest neighbor from multiple
neighbors which can act as relay vehicles, a new time-out mechanism
is presented to select the nearest neighbor by hop distance parameter
carried in Prefix Information Option. That is, a user vehicle
multicast NS messages to look for relay vehicles after RD failed and
wait for 1.5 seconds to receive all NA replies from neighbors. Each
NA carries its own global prefix(es) and the hop distance(s) in
Prefix Information Option. The user vehicle preserves every NA reply
in a temporary router list and select the one with least hop counts
as its relay vehicle after time out.
With receipt of NA, user vehicle configures its global address with
prefix information as mentioned in Section 7.1. After this, user
vehicle takes up to initiate the Address Registration along with DAD
process via relay vehicle. NS message is configured as specified in
Section 7.2 but indicate the relay vehicle's address as next-hop to
reach the RSU. In such a case, when relay vehicle receives relay
request message, it will forward NS message to RSU. The procedure
sets up on the rails except MA will include the relay vehicle's
address as relay address in NCE to indicate that at this moment, it
is not a directly attached vehicle, and sets the relay address as
next-hop address. Relay vehicle forwards DAD result information
message to user vehicle as soon as it received.
7.3.3. DAD with multiple Intermediate Vehicles
This document supports multihop communications (e.g., multihop DAD
and UDP/TCP transmission) for remote vehicles through multiple relay
vehicles. Vehicles which have already finished DAD process can serve
as temporary routers and forward packets for remote vehicles.
A new routing mechanism is specified to accomplish route selections
among user vehicles and serving RSUs when multiple vehicles act as
relay vehicles. Taking advantage of the Destination-Sequenced
Distance-Vector routing protocol (DSDV) [DSDV], this new routing
approach supposes that each vehicle holds a Neighbor Routing
Table which integrates the neighbor information in Neighbor Cache and
forwarding records for remote vehicles. Each vehicle which acts as a
relay vehicle for this remote vehicle will make records in its
Neighbor Routing Table.
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Figure 9 specifies an example of parameters in Neighbor Routing
Table when more than one vehicle work as intermediate relay vehicles.
In Figure 9, Vehicle3 connects RSU1 indirectly via Vehicle2 and
Vehicle1. When Vehicle1 and Vehicle2 forward messages for Vehicle3,
they make records in its Neighbor Routing Table including the next-
hop node to indicate the route to Vehicle3. This can ensure that the
packets from a source vehicle can be successfully transmitted to an
RSU as well as the reverse packet path exists from the RSU to the
source vehicle.
+--------+ +--------+ +--------+ +--------+
|Vehicle3|<......>|Vehicle2|<........>|Vehicle1|<.......> | RSU1 |
| (V3) | V2V | (V2) | V2V | (V1) | V2I | |
+--------+ +--------+ +--------+ +--------+
+------------+ +------------+ +------------+ +------------+
|Node|NextHop| |Node|NextHop| |Node|NextHop| |Node|NextHop|
+------------+ +------------+ +------------+ +------------+
| V2 | V2 | | V1 | V1 | |RSU1| RSU1 | | V1 | V1 |
+------------+ | V3 | V3 | | V2 | V2 | | V2 | V1 |
+------------+ | V3 | V2 | | V3 | V1 |
+------------+ +------------+
Figure 9: An Example of Neighbor Routing Table when multiple
Vehicles act as Relay Vehicles
7.4. Pseudonym Handling
Considering the privacy protection of a vehicle, a pseudonym
mechanism for its link-layer address is requested. This mechanism
periodically modifies the link-layer address, leading to the update
of the corresponding IP address. A random MAC Address Generation
mechanism is proposed in Appendix F.4 of [IEEE-802.11-OCB] by
generating the 46 remaining bits of MAC address using a random number
generator. When it changes its MAC address, a vehicle should ask the
serving RSU to update its own NCE, and to register its IP address
into the MA again.
8. Security Considerations
This document shares all the security issues of the neighbor
discovery protocol and 6LoWPAN protocol. This document can get
benefits from secure neighbor discovery (SEND) [RFC3971] in order to
protect ND from possible security attacks.
9. References
9.1. Normative References
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005,
<https://www.rfc-editor.org/info/rfc3971>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>.
[RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing
Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889,
September 2010, <https://www.rfc-editor.org/info/rfc5889>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013,
<https://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8691] Benamar, N., Härri, J., Lee, J., and T. Ernst, "Basic
Support for IPv6 Networks Operating Outside the Context of
a Basic Service Set over IEEE Std 802.11", RFC 8691,
DOI 10.17487/RFC8691, December 2019,
<https://www.rfc-editor.org/info/rfc8691>.
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[RFC9365] Jeong, J., Ed., "IPv6 Wireless Access in Vehicular
Environments (IPWAVE): Problem Statement and Use Cases",
RFC 9365, DOI 10.17487/RFC9365, March 2023,
<https://www.rfc-editor.org/info/rfc9365>.
9.2. Informative References
[I-D.jeong-ipwave-iot-dns-autoconf]
Jeong, J. P., Ahn, Y., Lee, S., and J. Park, "DNS Name
Autoconfiguration for Internet-of-Things Devices in IP-
Based Vehicular Networks", Work in Progress, Internet-
Draft, draft-jeong-ipwave-iot-dns-autoconf-17, 8 February
2024, <https://datatracker.ietf.org/api/v1/doc/document/
draft-jeong-ipwave-iot-dns-autoconf/>.
[I-D.jeong-ipwave-vehicular-mobility-management]
Jeong, J. P., Mugabarigira, B. A., and Y. C. Shen,
"Vehicular Mobility Management for IP-Based Vehicular
Networks", Work in Progress, Internet-Draft, draft-jeong-
ipwave-vehicular-mobility-management-11, 8 February 2024,
<https://datatracker.ietf.org/api/v1/doc/document/draft-
jeong-ipwave-vehicular-mobility-management/>.
[DSRC-WAVE]
Morgan, Y., "Notes on DSRC & WAVE Standards Suite: Its
Architecture, Design, and Characteristics",
IEEE Communications Surveys & Tutorials, 12(4), 2012.
[IEEE-802.11p]
"Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications Amendment 6: Wireless
Access in Vehicular Environments", June 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.
[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 in Vehicular Environments - Security Services for
Applications and Management Messages", IEEE Std
1609.2-2016, March 2016.
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[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 in Vehicular Environments (WAVE) - Multi-Channel
Operation", IEEE Std 1609.4-2016, March 2016.
[VIP-WAVE] Cespedes, S., Lu, N., and X. Shen, "VIP-WAVE: On the
Feasibility of IP Communications in 802.11p Vehicular
Networks", IEEE Transactions on Intelligent Transportation
Systems, vol. 14, no. 1, March 2013.
[DSDV] Perkins, C. and P. Bhagwat, "Highly Dynamic Destination-
Sequenced Distance-Vector Routing (DSDV) for Mobile
Computers", ACM SIGCOMM, August 1994.
Appendix A. Acknowledgments
This work was supported by the National Research Foundation of Korea
(NRF) grant funded by the Korea government, Ministry of Science and
ICT (MSIT) (No. 2023R1A2C2002990).
This work was supported in part by Institute of Information &
Communications Technology Planning & Evaluation (IITP) grant funded
by the Korea government (MSIT)(No. 2022-0-01015, Development of
Candidate Element Technology for Intelligent 6G Mobile Core Network).
Appendix B. Contributors
This document is made by the group effort of IPWAVE working group.
Many people actively contributed to this document, such as Carlos J.
Bernardos and Russ Housley. The authors sincerely appreciate their
contributions.
The following are co-authors of this document:
Bien Aime Mugabarigira - Department of Electrical and Computer
Engineering, Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon,
Gyeonggi-do 16419, Republic of Korea. EMail: bienaime@skku.edu
Zhong Xiang - Department of Electrical and Computer Engineering,
Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do
16419, Republic of Korea. EMail: xz618@skku.edu
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Junhee Kwon - Department of Computer Science and Engineering,
Sungkyunkwan University, 2066 Seobu-ro Jangan-gu, Suwon, Gyeonggi-do
16419, Republic of Korea. EMail: juun9714@skku.edu
Appendix C. Changes from draft-jeong-ipwave-vehicular-neighbor-
discovery-16
The following changes are made from draft-jeong-ipwave-vehicular-
neighbor-discovery-16:
* This version updates the version number.
Authors' Addresses
Jaehoon Paul Jeong (editor)
Department of Computer Science and Engineering
Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu
Suwon
Gyeonggi-Do
16419
Republic of Korea
Phone: +82 31 299 4957
Email: pauljeong@skku.edu
URI: http://iotlab.skku.edu/people-jaehoon-jeong.php
Yiwen Chris Shen
Department of Computer Science and Engineering
Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu
Suwon
Gyeonggi-Do
16419
Republic of Korea
Phone: +82 31 299 4106
Email: chrisshen@skku.edu
URI: https://chrisshen.github.io
Sandra Cespedes
NIC Chile Research Labs
Universidad de Chile
Av. Blanco Encalada 1975
Santiago
Chile
Phone: +56 2 29784093
Email: scespede@niclabs.cl
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