MEXT R. Baldessari
Internet-Draft NEC Europe
Intended status: Informational T. Ernst
Expires: August 21, 2008 INRIA
A. Festag
NEC Germany
M. Lenardi
Hitachi Europe
February 18, 2008
Automotive Industry Requirements for NEMO Route Optimization
draft-ietf-mext-nemo-ro-automotive-req-00
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Abstract
This document specifies requirements for NEMO Route Optimization
techniques as identified by the automotive industry. Requirements
are gathered from the Car2Car Communication Consortium and ISO
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Technical Committee 204 Working Group 16 (CALM).
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. NEMO Automotive Deployments . . . . . . . . . . . . . . . . . 5
3.1. Car2Car Communication Consortium . . . . . . . . . . . . . 5
3.1.1. System and Protocol Architecture . . . . . . . . . . . 6
3.1.2. IPv6 Deployment . . . . . . . . . . . . . . . . . . . 10
3.1.3. Scope of NEMO . . . . . . . . . . . . . . . . . . . . 11
3.2. ISO TC204 WG 16 (CALM) . . . . . . . . . . . . . . . . . . 12
3.2.1. System and Protocol Architecture . . . . . . . . . . . 12
3.2.2. IPv6 Deployment . . . . . . . . . . . . . . . . . . . 16
3.2.3. Scope of NEMO . . . . . . . . . . . . . . . . . . . . 17
4. Example Use Cases . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Notification Services . . . . . . . . . . . . . . . . . . 17
4.2. Peer-to-peer Applications . . . . . . . . . . . . . . . . 17
4.3. Upload and Download Services . . . . . . . . . . . . . . . 17
4.4. Vehicles Monitoring . . . . . . . . . . . . . . . . . . . 18
4.5. Infortainment Applications . . . . . . . . . . . . . . . . 18
4.6. Navigation Services . . . . . . . . . . . . . . . . . . . 18
5. NEMO Route Optimization Scenarios . . . . . . . . . . . . . . 18
6. NEMO Route Optimization Requirements . . . . . . . . . . . . . 19
6.1. Req 1 - Separability . . . . . . . . . . . . . . . . . . . 19
6.2. Req 2 - RO Security . . . . . . . . . . . . . . . . . . . 20
6.3. Req 3 - Privacy Protection . . . . . . . . . . . . . . . . 20
6.4. Req 4 - Multihoming . . . . . . . . . . . . . . . . . . . 20
6.5. Req 5 - Efficient Signaling . . . . . . . . . . . . . . . 20
6.6. Req 6 - Switching HA . . . . . . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
10.2. Informative References . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
Intellectual Property and Copyright Statements . . . . . . . . . . 24
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1. Introduction
NEMO Basic Support [1] defines a protocol that provides IPv6 mobility
support for entire moving networks, where all data packets go through
the IPv6-in-IPv6 tunnel established between the Mobile Router (MR)
and the Home Agent (HA). As already pointed out in various documents
([5], [6] and [9]) this can have severe consequences on the
communication performances, as it causes data packets to follow a
path that can be very far from optimal and requires a double IPv6
header for every packet exchanged with a Correspondent Node (CN) in
the Internet. Compared with a communication that uses the ideal
packet routing and the normal IPv6 header size, these factors result
in an increased delay and a reduced throughput, plus indirect
consequences like increased packet fragmentation and overall less
efficient usage of resources.
Various projects and consortia involving the automotive industry are
considering NEMO as part of their protocol stack for the provisioning
of session continuity and global reachability. Nevertheless, the
lack of standardized Route Optimization (RO) techniques allowing data
packets to be exchanged directly between vehicles or between vehicles
and hosts in the Internet is regarded as an obstacle for the actual
deployment of this protocol. As the definition of a general NEMO
Route Optimization technique is highly complex, it appears more
reasonable to address specific deployment requirements and design
more tailored, less complex schemes for Route Optimization.
This document gathers requirements from two bodies that are committed
in deploying vehicular communications including NEMO as part of their
protocol stacks.
o The Car2Car Communication Consortium [10] is an industry
consortium of car manufacturers and electronics suppliers
operating in Europe. Its mission is to establish an open European
industry standard for vehicular communications based on wireless
LAN technology. Its approach consists in considering vehicles as
a Vehicular ad hoc Network (VANET), where cars are equipped with
short-range communication devices that operate at frequencies
dedicated to safety and non-safety vehicular applications.
o ISO TC 204 WG 16 (CALM): ISO (International Standard Organization)
runs a number of Technical Committees. Members are nations and
offical participants represent their country. TC 204 is devoted
to Intelligent Transport Systems (ITS) and comprises a number of
Working Groups (16, but 12 still in operation). ISO TC 204 WG 16
is working on "Wide Area Communications Protocols and Interfaces"
and was established in year 2000. It is specifying a protocol
architecture from the physical layer up to the application layer
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and designed for all ITS types of communications (vehicle-vehicle,
vehicle-infrastructure, infrastrutcure-vehicle). Known as the
CALM architecture, the acronym was initially set to mean
"Communications Air-interface, Long and Medium range" but was
renamed in 2007 to "Communication Architecture for Land Mobile".
The document is organized as follows: Section 2 defines terminology.
Section 3 overviews the technical approaches adopted by the two
automotive bodies to deploy NEMO. Section 4 provides a non-
exhaustive list of use cases of NEMO in automotive applications.
Section 5 introduces the RO scenario and finally Section 6 lists the
requirements for NEMO RO.
2. Terminology
The following terms used in this document are defined in the Network
Mobility Support Terminology document [7]:
o Mobile Network
o Network Mobility (NEMO)
o Home Agent (HA)
o Home Address (HoA)
o Mobile Router (MR)
o Mobile Network Prefix (MNP)
o Mobile Network Node (MNN)
o Correspondent Router (CR)
o Correspondent Entity (CE)
The following new terms are used in this document:
o On Board Unit (OBU): a device installed in vehicles, implementing
the communication protocols and algorithm and equipped with at
least 1) a short-range wireless network interface operating at
dedicated frequencies and 2) a wireless or wired network interface
where Application Units (AU) can be attached to. With respect to
the NEMO terminology, the OBU is the physical machine acting as
MR, 1) is used as egress interface and 2) as ingress.
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o Application Unit (AU): a portable or built-in device connected
temporarily or permanently to the vehicle's OBU. It is assumed
that AUs support a standard TCP/IPv6 protocol stack. Devices
enhanced with Mobile IPv6, like hand-held user devices, also fall
into the definition of Application Unit. With respect to the NEMO
terminology, an AU is a generic MNN.
o Road Side Unit (RSU): a device installed along roadsides
implementing automotive communication protocols and algorithms.
RSUs can either be isolated or connected to a network
infrastructure. In the latter case, RSUs are attachment points
either acting themselves as IPv6 access routers or as bridges
directly connected to an access router.
o In-vehicle network: the wireless or wired network placed in a
vehicle and composed by (potentially) several AUs and one OBU.
o Vehicle-to-Vehicle (V2V) Communication Mode: a generic
communication mode in which data packets are exchanged between two
vehicles, either directly or by means of multi-hop routing,
without involving any node in the infrastructure.
o Vehicle-to-Infrastructure (V2I) Communication Mode: a generic
communication mode in which data packets sent or received by a
vehicle traverse a network infrastructure.
o Vehicle-to-Infrastructure-to-Vehicle (V2I2V) Communication Mode: a
generic communication mode in which data packets are exchanged
between two vehicles, by means of multi-hop routing involving a
RSU connected or not to a network infrastructure. From the point
of view of the communication and routing protocol, this mode is
equivalent to V2V, as RSUs act as relay in the same way OBUs do.
Nevertheless introducing this definition is beneficial from a
functional point of view.
3. NEMO Automotive Deployments
3.1. Car2Car Communication Consortium
The Car2Car Communication Consortium (C2C-CC [10]) is an industry
consortium of car manufacturers and electronics suppliers that
focuses on the definition of an European standard for vehicular
communication protocols. The Consortium gathers results from
research projects and aims at harmonizing their efforts. For the
standardization activity, the C2C-CC operates in cooperation with the
newly established ETSI TC ITS (Technical Committee Intelligent
Transportation System).
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The consortium's Manifesto [11] gives an overview of the system and
protocol architecture, as well as of the applications on which the
Consortium has agreed so far. In essence, this document defines a
C2C-C protocol stack that offers specialized functionalities and
interfaces to (primarily) safety-oriented applications and relies as
a communication technology on a modified version of IEEE 802.11p
[14]. This protocol stack is placed beside a traditional TCP/IP
stack, based on IP version 6, which is used mainly for non-safety
applications or potentially by any application that is not subject to
strict delivery requirements, including Internet-based applications.
The interaction between these stacks is currently discussed and
briefly overviewed in this document.
3.1.1. System and Protocol Architecture
The current draft reference architecture of the C2C communication
system is shown in Figure 1.
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| Internet |
| |
+---+-----------------+-+
| |
Access +--+-+ +--+-+ Access
Router | AR | | AR | Router
+--+-+ +--+-+
| |
--+---+--- --+---+--
| |
Road Side +--+--+ +--+--+ Public
Unit | RSU | | PHS | Hot Spot
+---+-+ +---+-+
| |
/\ /\
\_ \_
\_ \_
\ \
Mandatory \/
Mod IEEE 802.11p | __ \/ Optional IEEE
Interface +---+--+ \__ \/ | 802.11a/b/g
| OBU1 | | | Interface
+--+---+ +-+-----+---+
Vehicle1 | | OBU2 | On-Board
-+---+-+- +--+--------+ Unit
| | | Vehicle2
Application +--+-+ +-+--+ --+--+--
Units | AU | | AU | |
+----+ +----+ +-+--+
| AU |
+----+
Figure 1: C2C-CC Reference Architecture
Vehicles are equipped with networks logically composed of an OBU and
potentially multiple AUs. An AU is typically a dedicated device that
executes a single or a set of applications and utilizes the OBU
communication capabilities. An AU can be an integrated part of a
vehicle and be permanently connected to an OBU. It can also be a
portable device such as laptop, PDA or game pad that can dynamically
attach to (and detach from) an OBU. AU and OBU are usually connected
with wired connection, but the connection can also be wireless, such
as Bluetooth. The distinction between AU and OBU is logical, they
can also reside in a single physical unit.
Vehicles' OBUs and stationary units along the road, termed road-side
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units (RSUs), form a self-organizing network. An OBU is at least
equipped with a (short range) wireless communication device based on
draft standard IEEE 802.11p [14] (adapted to European conditions and
with specific C2C-C extensions) primarily dedicated for road safety,
and potentially with other optional communication devices. OBUs
directly communicate if wireless connectivity exist among them. In
case of no direct connectivity, multi-hop communication is used,
where data is forwarded from one OBU to another, until it reaches its
destination. For example in Figure 1, RSU and OBU1 have direct
connectivity, whereas OBU2 is out of RSU radio coverage but can
communicate with it through multi-hop routing.
The primary role of an RSU is improvement of road safety. RSUs have
two possible configuration modes: as isolated nodes, they execute
applications and/or extend the coverage of the ad hoc network
implementing routing functionalities. As attachment point connected
to an infrastructure network, RSUs distribute information originated
in the infrastructure and offer connectivity to the vehicles. As
result, for example, the latter configuration allows AUs registered
with an OBU to communicate with any host located in the Internet,
when at least one RSU connected to a network infrastructure is
available.
An OBU may also be equipped with alternative wireless technologies
for both, safety and non-safety. For example, an OBU may also
communicate with Internet nodes or servers via public wireless LAN
hot spots (PHS) operated individually or by wireless Internet service
providers. While RSUs for Internet access are typically set up with
a controlled process by a C2C-C key stake holder, such as road
administrators or other public authorities, public hot spots are
usually set up in a less controlled environment. These two types of
infrastructure access, RSU and PHS, also correspond to different
applications types. Other communication technologies, such as wide
coverage/cellular networks (e.g. UMTS, GPRS) do not fall in the
scope of the C2C-CC activity. Nevertheless, the C2C-CC aims at
guaranteeing future system extensibility and interoperability with
different technologies.
The protocol stack currently considered by the C2C-CC for OBUs is
depicted in Figure 2.
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+--------------------+------------------+
| | |
| C2C-CC | IP-based |
| Applications | Applications |
| | |
+--------------------+------------------+
| | TCP/UDP/... |
| C2C-CC Transport +------------------+
| | |
+--------------------+-----+ IPv6 |
| | |
| C2C-CC Network | |
| | |
+--------------------+-----+------------+
| Modified | Standard WLAN |
| IEEE 802.11p | IEEE 802.11a/b/g |
+--------------------+------------------+
Figure 2: OBU Protocol Stack
Protocol blocks are explained in the following list:
o Modified IEEE 802.11p: this block represents MAC and PHY layers of
a wireless technology based upon current draft standard IEEE
802.11p [14] but modified for usage in Europe. In Europe,
allocation of dedicated frequencies around 5.9 GHz for safety and
non-safety applications is in progress. Expected communication
range in line of sight is at least 500m. This network interface
is mandatory.
o IEEE 802.11a/b/g: this block represents MAC and PHY layers
provided by one ore more IEEE 802.11a/b/g network interfaces.
This network interface is optional but C2C-C Consortium encourages
its installation.
o C2C-CC Network: this block represents the network layer protocol
currently defined by the C2C-CC. The protocol provides secure ad
hoc routing and forwarding, as well as addressing, error handling,
packet sequencing, congestion control and information
dissemination. The specification of this protocol is currently
under discussion. Only the C2C-CC Network protocol can access the
Modified IEEE 802.11p network interface. The C2C-CC Network
protocol can also access the IEEE 802.11a/b/g interface. The
C2C-CC Network protocol offers an interface to the IPv6 protocol.
This interface allows IPv6 headers and payload to be encapsulated
into C2C-CC Network datagrams and sent over the Modified IEEE
802.11p or IEEE 802.11a/b/g network interface. The specification
of this interface is currently under discussion. A primary goal
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of the C2C-CC Network layer is to provide geographic routing and
addressing functionalities for cooperative safety applications.
Through the mentioned interface to the IPv6 protocol, these
functionalities are also available for IP-based applications.
o C2C-CC Transport: this block represents the transport layer
protocol that is currently being defined by the C2C-CC. This
protocol provides a selected set of traditional transport layer
functionalities (e.g. application data multiplexing/
demultiplexing, connection establishment, reliability etc.). The
specification of this protocol is currently under discussion.
o C2C-CC Applications: this block represents the application layer
protocol currently defined by the C2C-CC and concerns Active
Safety and Traffic Efficiency Applications.
3.1.2. IPv6 Deployment
As described in Section 3.1.1, the C2C-CC includes IPv6 as mandatory
part of its specified protocol architecture. Currently, three
methods are discussed for transmission of IPv6 headers and their
payload:
o On the Modified IEEE 802.11p interface via the C2C-CC Network
layer: in this method, IPv6 headers are encapsulated into C2C-CC
Network headers and sent using dedicated frequencies for inter-
vehicle communications. Since the C2C-CC Network layer provides
ad hoc routing, from the IPv6 layer perspective other nodes (OBUs
and RSU) appear as attached to the same link. The broadcast
domain used for IPv6 multicast traffic is selected by the C2C-CC
Network layer on a geographical basis. The C2C-CC Network layer
presents Ethernet-like characteristics, so that [4] can be
applied.
o On the IEEE 802.11a/b/g interface via the C2C-CC Network layer: in
this method, IPv6 headers are encapsulated into C2C-CC Network
headers and sent using license-free ISM frequency bands (wireless
LAN). Except the network interface, this method is equivalent to
the previous one.
o On the IEEE 802.11a/b/g interface directly: in this method, IPv6
headers are sent directly to the wireless LAN interface.
As a result, a C2C-CC OBU has at least two IPv6 network interfaces, a
real one (IEEE 802.11a/b/g) and a virtual one (tunnel over C2C-CC
Network layer). The following informational list briefly summarizes
some currently discussed design concepts:
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o in order to avoid address resolution procedures, vehicles only use
IPv6 addresses with as host part an EUI-64 identifier derived from
the MAC address. Privacy issues described in [3] are strongly
alleviated through the use of temporary, changing MAC addresses,
which are assigned in a set to every vehicle;
o according to the current availability of infrastructure
connectivity, OBUs can use (at least) 2 types of globally routable
IPv6 addresses: an IPv6 address configured using standard IPv6
stateless address configuration from Router Advertisements sent by
RSUs connected to a network infrastructure and an IPv6 address
configured from a prefix permanently allocated to the vehicle and
delegated to the vehicle from a home network. The former globally
routable IPv6 address is used as the NEMO Care-of Address (CoA)
and the latter as the NEMO Home Address (HoA). In addition, a
self-generated IPv6 address with as prefix part a pre-defined IPv6
prefix (either reserved for C2C-CC communications or a general
purpose one) may be used for ad-hoc communications with other
OBUs;
o RSUs can either act as IPv6 Access Routers or as bridges connected
to external IPv6 Access Routers. Different Access Routers are
responsible for announcing different network prefixes with global
validity. As a consequence, when roaming between different Access
Routers, vehicles experience layer 3 handovers.
When infrastructure access via RSUs is available, IPv6 support in
C2C-CC systems is enhanced with Mobility Support. As a vehicle
includes a set of attached devices (AUs), NEMO Basic Support is the
default protocol selected by the C2C-CC for maintaining ongoing
sessions during L3 handovers.
3.1.3. Scope of NEMO
The C2C-CC is defining a protocol stack for both safety and non-
safety applications. These two application categories put different
requirements on the protocol stack. Therefore the C2C-CC defined a
double protocol stack which is depicted in Figure 2. Applications
that are subject to safety requirements use the left part, whereas
applications that do not require these particular features use the
right part of the stack. The left part of the stack provides
functionalities like geographic packet distribution, information
dissemination according to relevance, information aggregation using
cross-layer analysis, security and plausibility checks at different
protocol layers. The right part of the stack is designed for non-
safety applications and for non-critical applications, which can
still support safety.
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The deployment of NEMO in C2C-CC systems is achieved through the
right part of the stack depicted in Figure 2 and targets non-safety
applications. Nevertheless, applications using NEMO might indirectly
support safety applications. Example use cases are listed in
Section 4.
3.2. ISO TC204 WG 16 (CALM)
ISO TC 204 WG 16 (CALM) is working on "Wide Area Communications
Protocols and Interfaces" and was established in year 2000. The WG
is itself devided into a number of sub-groups.
The purpose of this WG is specifying a protocol architecture from the
physical layer up to the application layer and designed for all ITS
types of communications. media.
The CALM handbook [12] gives an overview of the system and protocol
architecture. In essence, this document defines a protocol stack
that offers specialized functionalities and interfaces to safety and
non-safety applications and doesn't rely on a specific communication
technology. This protocol stack allows for both IP and non-IP types
of communications. The IP version 6 is the version considered for IP
types of flows.
3.2.1. System and Protocol Architecture
The current draft reference CALM architecture [13] is shown in
Figure 3.
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| Internet |
| |
+---+-----------------+-+
| |
Access +--+-+ +--+-+ Access
Router | AR | | AR | Router
+--+-+ +--+-+
| |
--+---+--- --+---+--
| |
Road Side +--+--+ +--+--+ Public
Unit | RSU | | PHS | Hot Spot
+---+-+ +---+-+
| |
/\ /\
\_ \_
\_ \_
\ \
Optional \/ \/
IEEE 802.11a/b/g and 802.11p | | __ \/ Optional IEEE
Interfaces +--+---+--+ \__ \/ | 802.11a/b/g and 3G
| OBU1 | | | Interfaces
+--+---+--+ +-+-----+---+
Vehicle1 | | OBU2 | On-Board
-+---+-+- +--+--------+ Unit
| | | Vehicle2
Application +--+-+ +-+--+ --+--+--
Units | AU | | AU | |
+----+ +----+ +-+--+
| AU |
+----+
Figure 3: ISO's CALM scenarios
Vehicles are equipped with networks logically composed of an
(potentially multiple) OBU(s) and potentially multiple AUs. An AU is
typically a dedicated device that executes a single or a set of
applications and utilizes the OBU communication capabilities. An AU
can be an integrated part of a vehicle and be permanently connected
to an OBU. It can also be a portable device such as laptop, PDA or
game pad that can dynamically attach to (and detach from) an OBU. AU
and OBU are usually connected with wired connection, but the
connection can also be wireless, such as Bluetooth. The distinction
between AU and OBU is logical, they can also reside in a single
physical unit.
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Vehicles' OBUs and stationary units along the road, termed road-side
units (RSUs), form a self-organizing network. An OBU is equipped
with a number of short range, medium range and long range wireless
communication devices, typically IEEE 802.11p [14], IEEE 802.11a/b/g
or 3G. OBUs can communicate with one another, either directly if
wireless connectivity exist among them, via multi-hop communication
where data is forwarded from one OBU to another, until it reaches its
destination, through the roadside infrastrucure, or through the
Internet. For example in Figure 3, RSU and OBU1 have direct
connectivity, whereas OBU2 is out of RSU radio coverage but can
communicate with it through multi-hop routing or through the
Internet.
The primary role of an RSU is improvement of road safety and road
traffic. RSUs have two possible configuration modes: as isolated
nodes, they execute applications and/or extend the coverage of the ad
hoc network implementing routing functionalities. As attachment
point connected to an infrastructure network, RSUs distribute
information originated in the infrastructure and offer connectivity
to the vehicles. As result, for example, the latter configuration
allows AUs registered with an OBU to communicate with any host
located in the Internet, when at least one RSU connected to a network
infrastructure is available.
An OBU is equipped with alternative wireless technologies for both
safety and non-safety applications. For example, an OBU may also
communicate with Internet nodes or servers via public wireless LAN
hot spots (PHS) or wide coverage/cellular networks (e.g. UMTS, GPRS)
operated individually or by wireless Internet service providers.
While RSUs for Internet access are typically set up with a controlled
process by a CALM key stake holder, such as road administrators or
other public authorities, public hot spots are usually set up in a
less controlled environment. These two types of infrastructure
access, RSU and PHS, also correspond to different applications types.
Other communication technology not currently available or de facto
considered in the CALM architecture may be added at will.
CALM allows all communication modes:
o in Vehicle-to-Vehicle (V2V) mode, data packets are exchanged
directly between OBUs, either via multi-hop or not, without
involving any RSU;
o in Vehicle-to-Infrastructure mode (V2I), an OBU exchanges data
packets through a RSU with an arbitrary node connected to the
infrastructure (potentially another vehicle not attached to the
same RSU).
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o in Vehicle-to-Infrastructure-to-Vehicle mode (V2I2V), an OBU
exchanges data packets with another OBU through an arbitrary node
in the infrastructure or the Internet;
o in Vehicle-to-Internet mode (Internet), an OBU exchanges data
packets with an an arbitrary node in the Internet.
The CALM protocol stack considered by ISO is depicted in Figure 4.
+--------------------+--------------------+-----------------+
| | | |
| Non-IP CALM Aware | IP-based CALM | IP-based Legacy |
| Aware Applications | Aware Applications | Applications |
| | | |
+ +---------+--------------------+-----------------+
| | |
| | TCP/UDP/... |
| | |
+ +------------------------------------------------+
| | |
| | CALM IPv6 |
| | |
+----------------+------------------+-------+---------+-----+
| IEEE 802.11p | Standard WLAN | 2G/3G | CALM IR | ... |
| M5/WAVE/DSRC | IEEE 802.11a/b/g | GSM | | ... |
+----------------+------------------+-------+---------+-----+
Figure 4: CALM Reference Architecture
Protocol blocks are explained in the following list:
o M5, WAVE and DSRC are IEEE 802.11p variants, in Europe, USA and
Japan, respectivelty: this block represents MAC and PHY layers of
a wireless technology based upon current draft standard IEEE
802.11p [14] but modified for usage in Europe. In Europe,
allocation of dedicated frequencies around 5.9 GHz for safety and
non-safety applications is in progress. Expected communication
range in line of sight is around 500m.
o IEEE 802.11a/b/g: this block represents MAC and PHY layers
provided by one ore more IEEE 802.11a/b/g network interfaces.
o CALM IPv6 Network: this block represents the IPv6-based network
layer protocol currently defined by ISO. The specification of
this layer is currently under discussion. Several scenarios are
proposed, one for IP communications without mobility management,
one for IP communications with host-mobility management (MIPv6),
and one with IP communications with network mobility management
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(NEMO). The former two are out of scope of the present document.
This block comprises the NME (Network Management Entity) which is
able to interoperate with other layers in order to negociate
priority flow requirements
o CALM Aware Applications: this block represents specifically
designed ITS applications. CALM Aware applications are ranged
into IP and non IP applications. This block comprises the CME
(CALM Management Entity) which is able to interoperate with lower
layers in order to negociate priority flow requirements.
3.2.2. IPv6 Deployment
The CALM architecture includes IPv6 as mandatory part of its
specified protocol architecture.
The following informational list briefly summarizes currently
discussed design concepts:
o in order to avoid address resolution procedures, vehicles use only
IPv6 addresses with as host part an EUI-64 identifier derived from
the MAC address. Privacy issues described in [3] are strongly
alleviated through the use of temporary, changing MAC addresses,
which are assigned in a set to every vehicle (as part of their
assigned "pseudonyms");
o according to the current availability of infrastructure
connectivity, OBUs can use (at least) 2 types of globally routable
IPv6 addresses: an IPv6 address configured using standard IPv6
stateless address configuration from Router Advertisements sent by
RSUs connected to a network infrastructure and an IPv6 address
configured from a prefix permanently allocated to the vehicle and
delegated to the vehicle from a home network. The former globally
routable IPv6 address is used as the NEMO Care-of Address (CoA)
and the latter as the NEMO Home Address (HoA). In addition, a
self-generated IPv6 address with as prefix part a pre-defined IPv6
prefix (either reserved for ISO CALM communications or a general
purpose one) may be used for ad-hoc communications with other
OBUs;
o RSUs can either act as IPv6 Access Routers or as bridges connected
to external IPv6 Access Routers. Different Access Routers are
responsible for announcing different network prefixes with global
validity. As a consequence, when roaming between different Access
Routers, vehicles experience layer 3 handovers.
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3.2.3. Scope of NEMO
In all the methods for use of IPv6 in the CALM architecture as
described above, the IPv6 layer is meant to be enhanced with Mobility
Support. As a vehicle includes a set of attached devices (AUs), NEMO
Basic Support is the default protocol selected by ISO for maintaining
ongoing sessions during L3 handovers.
4. Example Use Cases
In this section, the main use cases are listed that have been
identified by the C2C-CC and ISO for usage of NEMO: notification
services, peer-to-peer applications, upload/download services,
navigation services, multimedia applications.
4.1. Notification Services
A generic notification service delivers information to subscribers by
means of the Internet. After subscribing the service with a
provider, a user is notified when updates are available. Example
services are weather, traffic or news reports, as well as commercial
and technical information from the car producer or other companies.
In this use case, the HoA or a pre-defined address belonging to the
MNP is registered to the service provider. The service provider
sends the updates to this address which does not change while the
vehicle changes point of attachment.
4.2. Peer-to-peer Applications
A generic peer-to-peer application exchanges data directly between
vehicles, without contacting any application server. Data traffic
goes through a network infrastructure (V2I or V2I2V) or directly
between cars when the infrastructure is not available (V2V). Example
applications are vehicle-to-vehicle instant messaging (chat) and off-
line messaging (peer-to-peer email), vehicle-to-vehicle voice over IP
and file exchange.
The C2C-CC also considers this use case when vehicles are isolated
from the infrastructure, i.e. V2V mode. As the NEMO protocol is not
involved when infrastructure access is not available, this particular
case is out of scope of this document.
4.3. Upload and Download Services
A generic upload/download service via the Internet consists in simple
file exchange procedures with servers located in the Internet. The
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service is able to resume after a loss of connectivity.
4.4. Vehicles Monitoring
Vehicles monitoring services allow car manufacturers, car garages and
other trusted parties to remotely monitor vehicle statistics. Data
is collected by the OBU and sent to the service center via the
Internet.
As an example, car manufacturers or garages offering this service
could deploy NEMO Home Agents to serve thousands of cars.
4.5. Infortainment Applications
TBD by ISO CALM
4.6. Navigation Services
TBD by ISO CALM
5. NEMO Route Optimization Scenarios
In this section, operational characteristics of automotive
deployments of NEMO are described that are relevant for the design of
Route Optimization techniques. In particular a restriction of the
general solution space for RO and motivations for RO requirements
described in Section 6 are provided.
With respect to the classification of NEMO Route Optimization
scenarios described in [6], the non-nested NEMO RO case (Section 3.1)
is considered as the most important for the automotive deployment.
However, MIPv6-enabled AUs (i.e. VMNs) and nested Network Mobility
are allowed in ISO CALM but not specifically addressed.
The requirements defined in this document refer to RO between MR and
CE (Correspondent Entity). According to the automotive use cases,
the CE can be:
1. Another vehicle, i.e. another automotive MR.
2. A dedicated node (host or router) installed on the roadside (2a)
or in the Internet (2b) for automotive applications.
3. An arbitrary node in the Internet.
In cases 1 and 2, the CE is a newly deployed entity. Whereas the
communicating peers in case 1 are obvious, case 2 includes for
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example information points installed along the road, control centers,
notification points and infotainment service providers located in the
infrastructure.
The suboptimal routing due to the lack of RO has the most negative
impact when the topological distance between MR and CE is
considerably smaller than between MR and HA. This is highly likely
to occour in case 1 (e.g. two neighboring vehicles communicating with
each others) and case 2a (e.g. vehicles receiving updates from
information points installed on the roadside). For these two cases,
the suboptimal routing might represent a limiting factor for the
system performance and, in turn, a limiting factor for the deployment
of NEMO.
In cases 2b and 3, the impact of suboptimal routing depends on the
arbitrary CE topological position. At this point of time no
particular assumption can be made on the topological position of CE
in case 2b and, obviously, in case 3. Consequently, the case 1 and
2a deserve a higher priority with respect to the definition of a NEMO
RO solution for automotive applications.
Any available information about the geographical or topological
position of the CE is relevant for the MR in order to apply RO. In
this respect, external information might be used to define policy
rules specifying whether or not RO should be enabled with a
particular pre-defined CE, which is known in advanced to the MR.
6. NEMO Route Optimization Requirements
Table Figure 5 summarizes which requirement applies to both C2C-CC
and ISO, or only one of these.
6.1. Req 1 - Separability
A RO technique, including its establishment procedure, MUST have the
ability to be enabled on a per-flow basis according to pre-defined
policies. Policies criteria for the switching to RO MUST at least
include the end points' addresses and the MNP for which RO is to be
established. Policies MAY change dynamically.
In some scenarios it might not be beneficial to activate RO due to
the intermittent connectivity. Based on external information, a
management instance of the MR can dynamically specify policies for RO
establishment of a particular IPv6 flow. Furthermore, policies can
prevent unnecessary or unwanted RO sessions to take place (e.g. DNS
queries, location privacy protection etc.). In case of MRs serving
multiple MNPs (e.g. served by different HAs or MNPs that vary only in
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the length), the policies allow for specifying for which MNP RO
should be established (i.e. prefix including length).
6.2. Req 2 - RO Security
As a minimum security feature, an RO technique MUST prevent off-path
malicious nodes to claim false MNP ownership. Further security
requirements are TBD.
As a minimum requirement, the security level of a RO scheme should be
comparable with today's Internet.
6.3. Req 3 - Privacy Protection
A RO technique MUST NOT allow off-path malicious nodes to match the
MR's CoA with its MNP or HoA.
In other words, the RO technique must not expose the MNP/HoA to nodes
other than the CE and, indirectly, the nodes on the path between the
MR and the CE.
6.4. Req 4 - Multihoming
A RO technique MUST allow a MR to be simultaneously connected to
multiple access networks, having multiple prefixes and Care-Of
Addresses in a MONAMI6 context, and be served by multiple HAs.
Adopting the classification of [8], the automotive NEMO deployment
includes at least the cases (1,n,n), (n,1,1) and (n,n,n). Case
(1,n,n) takes place when a single MR is installed in the vehicle's
OBU but different MNPs/HAs are used for different purposes (e.g.
vehicle monitoring, traffic information, infotainment) or to achieve
better fault tolerance. Cases (n,1,1) and (n,n,n) take place when
the vehicle's connectivity is enhanced by installing additional NEMO
MRs in a separated unit in a later stage. A RO technique must not
prevent any of these three configurations from working properly.
6.5. Req 5 - Efficient Signaling
A RO technique MUST be capable of efficient signaling. The number of
per-flow signaling messages for the establishment of RO SHOULD be
smaller than TBD and the number of per-flow signaling messages upon a
layer 3 handover should be smaller than TBD.
6.6. Req 6 - Switching HA
A RO technique MUST allow a MR to switch from one HA to another one
topologically distant from the first one.
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+====================================================+
| | C2C-CC | ISO CALM |
+====================================================+
| #1: Separability | x | x |
+--------------------------------+--------+----------+
| #2: RO Security | x | x |
+--------------------------------+--------+----------+
| #3: Privacy Protection | x | x |
+--------------------------------+--------+----------+
| #4: Multihoming | x | x |
+--------------------------------+--------+----------+
| #5: Efficient Signaling | x | x |
+--------------------------------+--------+----------+
| #6: Switching HAs | | x |
+====================================================+
Figure 5: C2C-CC and ISO CALM requirements
7. IANA Considerations
This document does not require any IANA action.
8. Security Considerations
This document does not specify any protocol therefore does not create
any security threat. However, it specifies requirements for a
protocol that include security and privacy issues.
9. Acknowledgments
The authors would like to thank the members of the work groups PHY/
MAC/NET and APP of the C2C-C Consortium and in particular Tim
Leinmueller, Bernd Bochow, Andras Kovacs and Matthias Roeckl.
10. References
10.1. Normative References
[1] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
[2] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
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[3] Narten, T. and R. Draves, "Privacy Extensions for Stateless
Address Autoconfiguration in IPv6", RFC 3041, January 2001.
[4] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, December 1998.
10.2. Informative References
[5] Ng, C., Thubert, P., Watari, M., and F. Zhao, "Network Mobility
Route Optimization Problem Statement", July 2007.
[6] Ng, C., Zhao, F., Watari, M., and P. Thubert, "Network Mobility
Route Optimization Solution Space Analysis", July 2007.
[7] Ernst, T. and H-Y. Lach, "Network Mobility Support
Terminology", RFC 4885, July 2007.
[8] Ng, C., Ernst, T., Paik, E., and M. Bagnulo, "Analysis of
Multihoming in Network Mobility Support", RFC 4980,
October 2007.
[9] Eddy, W., Ivancic, W., and T. Davis, "NEMO Route Optimization
Requirements for Operational Use in Aeronautics and Space
Exploration Mobile Networks", draft-ietf-mext-aero-reqs-00
(work in progress), December 2007.
[10] "Car2Car Communication Consortium Official Website",
http://www.car-2-car.org/ .
[11] "Car2Car Communication Consortium Manifesto",
http://www.car-2-car.org/index.php?id=570 , May 2007.
[12] "The CALM Handbook", http://www.calm.hu , May 2005.
[13] "CALM - Medium and Long Range, High Speed, Air Interfaces
parameters and protocols for broadcast, point to point,
vehicle to vehicle, and vehicle to point communication in the
ITS sector - Networking Protocol - Complementary Element", ISO
Draft ISO/WD 21210, February 2005.
[14] "Draft Amendment to Standard for Information Technology .
Telecommunications and information exchange between systems .
Local and Metropolitan networks . Specific requirements - Part
11: Wireless LAN Medium Access Control (MAC) and Physical Layer
(PHY) specifications: Amendment 3: Wireless Access in Vehicular
Environments (WAVE)", IEEE P802.11p/D1.0, February 2006.
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Authors' Addresses
Roberto Baldessari
NEC Europe Network Laboratories
Kurfuersten-anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 4342167
Email: roberto.baldessari@nw.neclab.eu
Thierry Ernst
INRIA
INRIA Rocquencourt
Domaine de Voluceau B.P. 105
Le Chesnay, 78153
France
Phone: +33-1-39-63-59-30
Fax: +33-1-39-63-54-91
Email: thierry.ernst@inria.fr
URI: http://www.nautilus6.org/~thierry
Andreas Festag
NEC Deutschland GmbH
Kurfuersten-anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 4342147
Email: andreas.festag@nw.neclab.eu
Massimiliano Lenardi
Hitachi Europe SAS Sophia Antipolis Laboratory
Immeuble Le Theleme
1503 Route des Dolines
Valbonne F-06560
France
Phone: +33 489 874168
Email: massimiliano.lenardi@hitachi-eu.com
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