ETSI TS 102 636-6-1 V1.1.1 (2011-03)

Intelligent Transport Systems (ITS); Vehicular Communications; GeoNetworking; Part 6: Internet Integration; Sub-part 1: Transmission of IPv6 Packets over GeoNetworking Protocols

DTS/ITS-0030005

General Information

• Status: Published
• Publication Date: 29-Mar-2011
• Technical Committee: ITS WG3 - Transport and Network
• Current Stage: 12 - Completion
• Due Date: 30-Mar-2011
• Completion Date: 30-Mar-2011
• Mandate: M/453

Standards Content (Sample)

Technical Specification
Intelligent Transport Systems (ITS);
Vehicular Communications;
GeoNetworking;
Part 6: Internet Integration;
Sub-part 1: Transmission of IPv6 Packets over
GeoNetworking Protocols
2 ETSI TS 102 636-6-1 V1.1.1 (2011-03)

Reference
DTS/ITS-0030005
Keywords
ITS, IPv6, addressing, network,
point-to-multipoint, point-to-point, protocol
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ETSI
3 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 6
1 Scope . 8
2 References . 9
2.1 Normative references . 9
2.2 Informative references . 10
3 Definitions, symbols and abbreviations . 12
3.1 Definitions . 12
3.2 Symbols . 12
3.3 Abbreviations . 12
4 GN6ASL in the ITS station architecture . 13
5 IPv6 link models and interfaces . 14
5.1 Rationales . 14
5.2 Required properties of supported IPv6 link models . 15
5.2.1 Number and types of virtual link . 15
5.2.2 Geographical virtual links . 15
5.2.3 Topological virtual links . 15
5.3 Recommended properties of virtual interfaces . 15
5.3.1 Number and types of virtual interfaces . 15
5.3.2 Usage of specific virtual interfaces . 16
5.3.2.1 Ethernet V2.0/IEEE 802.3 LAN virtual interfaces . 16
5.3.2.2 NBMA virtual interfaces . 16
5.3.2.3 Point-to-point virtual interfaces . 16
6 Bridging support . 17
6.1 Rationales . 17
6.2 Required properties . 18
6.3 Media-dependent implementations . 18
6.3.1 IEEE 802 integration service . 18
7 IPv6/GeoNetworking interface service specification . 19
8 Encapsulation characteristics . 19
8.1 Maximum transmission unit . 19
8.2 Packet delivery . 19
8.2.1 Outbound traffic . 19
8.2.2 Inbound traffic . 21
8.3 Frame format . 22
9 IPv6 multicast and anycast support . 23
9.1 Overview . 23
9.2 Legacy IPv6 multicast support . 23
9.2.1 IPv6 link-local multicast . 23
9.2.2 IPv6 wider-scope multicast . 24
9.2.3 Geocasting of legacy IPv6 multicast traffic . 24
9.3 Legacy IPv6 anycast support . 24
10 IPv6 neighbor discovery support . 24
10.1 On-link determination . 24
10.2 Address configuration . 25
10.2.1 Stateless address autoconfiguration . 25
10.2.2 Stateful address configuration. 25
10.2.3 Manual address configuration . 26
10.3 Address resolution . 26
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4 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
10.3.1 Non-ND-based address resolution . 26
10.3.2 ND-based address resolution . 26
10.4 Neighbor unreachability detection . 27
10.5 Protocol constants. 27
11 Support for pseudonym change . 27
11.1 Rationales . 27
11.2 Required operations . 28
Annex A (normative): ASN.1 encoding of the GN6ASL MIB . 29
A.1 Modules . 29
A.1.1 ITSGN6ASL-MIB . 29
Annex B (normative): MIB attributes . 32
B.1 ITSGN6ASL-MIB attributes values . 32
Annex C (informative): IPv6/GeoNetworking data SAP . 33
C.1 Basic data SAP (GN6_SAP) . 33
C.1.1 Overview . 33
C.1.2 Service primitives . 33
C.1.2.1 GN6-UNITDATA.request . 33
C.1.2.1.1 Semantics . 33
C.1.2.1.2 When generated . 33
C.1.2.1.3 Effect on receipt . 33
C.1.2.2 GN6-UNITDATA.indication . 34
C.1.2.2.1 Semantics . 34
C.1.2.2.2 When generated . 34
C.1.2.2.3 Effect on receipt . 34
C.2 Experimental extended data SAP (EGN6_SAP) . 34
C.2.1 Overview . 34
C.2.2 Service primitives . 35
C.2.2.1 EGN6-UNITDATA.request . 35
C.2.2.1.1 Semantics . 35
C.2.2.1.2 When generated . 35
C.2.2.1.3 Effect on receipt . 35
C.2.2.2 EGN6-UNITDATA.indication . 35
C.2.2.2.1 Semantics . 35
C.2.2.2.2 When generated . 36
C.2.2.2.3 Effect on receipt . 36
Annex D (informative): Geographic IPv6 multicast support (experimental) . 37
D.1 Overview . . 37
D.2 Pre-defined geographical IPv6 multicast groups . 37
D.3 Other studied mechanisms. 37
Annex E (informative): Exemplary implementations . 39
E.1 Virtual links and interfaces . 39
E.2 Packet delivery with Ethernet V2.0/IEEE 802.3 LAN virtual interfaces . 39
E.2.1 Outbound traffic . 39
E.2.2 Inbound traffic . 40
E.3 Bridging support . 40
E.4 GeoNet project implementations results . 41
Annex F (informative): Support for Network Mobility Basic Support . 42
F.1 Purpose of this annex . 42
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5 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
F.2 Mode of operation via GN6ASL . 42
F.3 Sub-optimal routing issues . 42
Annex G (informative): Security and privacy considerations . 43
G.1 Purpose of this annex . 43
G.2 Recommendations for security mechanisms . 43
G.3 Recommendations for privacy-protecting deployment . 43
Annex H (informative): Bibliography . 44
History . 45

ETSI
6 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Intelligent Transport System (ITS).
The present document is part 6, sub-part 1 of a multi-part deliverable covering GeoNetworking and Transport, as
identified below:
Part 1: "Requirements for GeoNetworking and Data Transport Protocol ";
Part 2: "Scenarios for GeoNetworking";
Part 3: "Network architecture";
Part 4: "Geographical addressing and forwarding for point-to-point and point-to-multipoint communications;
Part 5: "Transport protocols";
Part 6: "Internet integration";
Sub-part 1: "Transmission of IPv6 Packets over GeoNetworking Protocols";
Part 7: "Network management";
Introduction
The ETSI GeoNetworking protocol [i.25] and [i.26] is a non-IP network-layer protocol that provides geographic
addressing and forwarding. Applications and facilities specifically designed for GeoNetworking exploit these
functionalities, for example to disseminate warning or generic information messages to geographically scoped areas.
This approach satisfies the requirements of several ITS services, whose application domain is limited to networks that
are disconnected from large existing network infrastructures. However, several ITS applications require the integration
of ITS stations with larger networks like private transport networks or the Internet.
In order to connect networks based on GeoNetworking to networks running the Internet Protocol (IP), which represent
the majority of currently deployed large networks, it is necessary to allow GeoNetworking stations to act like Internet
hosts or routers. ETSI Technical Committee ITS recognizes IP version 6 (IPv6,[7]) as the primary and only version of
IP to be necessarily supported by ITS stations.
The present document introduces a set of mechanisms that allow GeoNetworking to transport IPv6 packets without
introducing modifications to existing IPv6 protocol implementations. By deploying these mechanisms, the following
two main advantages are achieved:
1) coverage offered by point-of-attachment to the Internet like road-side ITS stations is extended by means of
sub-IP geographic routing; and
2) IPv6 multicast traffic can be geocasted, i.e. addressed and delivered to all ITS stations currently located within
a geographic area.
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7 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
The present document includes a data SAP that enables an IPv6 protocol entity to send and receive packets over
GeoNetworking. This SAP is defined in annex C. The present document does not include a management SAP towards
the ITS station management entity.
NOTE: In the reminder of the present document, when the sole term "GeoNetworking" is used, it is to be
intended as the ETSI GeoNetworking protocol consisting of the combination of the media-independent
part [i.25] and at least one of the media-dependent parts (such as [i.26]). It should be noted that the
media-dependent extensions do not represent distinct protocol layers.
ETSI
8 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
1 Scope
The present document specifies the transmission of IPv6 packets over the ETSI GeoNetworking protocol [i.25] via a
protocol adaptation sub-layer referred to as the GN6ASL (GeoNetworking to IPv6 Adaptation Sub-Layer). The scope of
the present document is limited to the GN6ASL.
The techniques specified in the present document fulfil the requirements for GeoNetworking and IPv6 integration
described in [3], clause 5.9. In particular, these techniques allow for the transport of IPv6 packets by ETSI
GeoNetworking protocol [i.25], enabling sub-IP multi-hop delivery of IPv6 packets, e.g. in a vehicular network. As a
result, the connectivity provided by point-of-attachments to IPv6 infrastructure networks is extended by means of
mobile relay nodes. In addition to that, the techniques described in the present document allow for geocasting of IPv6
multicast packets.
The scope of the GN6ASL is limited to the fulfilment of the requirements for GeoNetworking and IPv6 integration
described in [3], clause 5.9, by enabling an ITS station including a Geoadhoc router [5] running GeoNetworking and an
IPv6-compliant protocol layer to:
1) exchange IPv6 packets with other ITS stations using link-local IPv6 addresses;
2) acquire globally routable IPv6 unicast addresses and communicate with an arbitrary IPv6 host located in the
Internet, whenever an ITS station including a Geoadhoc router and including or connected to an access
router [5] providing IPv6 connectivity to the Internet is reachable directly or via other relay ITS stations;
3) to perform the operations required by [20] for a Mobile Router whenever i) an ITS mobile router supporting
Network Mobility Basic Support (NEMO BS) [20] is present in the ITS station and runs on top of the
GN6ASL and ii) an ITS station including a Geoadhoc router and including or connected to an access router [5]
providing IPv6 connectivity to the Internet is reachable directly or via other relay ITS stations.
NOTE: The present document adopts the definition of "IPv6-compliant" and "sub-IP multi-hop delivery"
introduced in clause 3.1.
Extending the IPv6 basic standards [7], [8], [9], [10] and [12] to support new features is outside the scope of the present
document. Extensions to NEMO BS [15] are outside the scope of the present document. Mechanisms for the
dissemination of IPv6 routing information for hosts and routers not directly attaching to the network where
GeoNetworking is used are outside the scope of the present document (e.g. discovery of IPv6 in-vehicle prefixes).
However, the present document aims at providing the underlying support for the dissemination of such routing
information, i.e. IPv6 multicast support for the network where the GeoNetworking protocol is used.
With respect to IPv6 multicast and anycast support, the present document is limited to the support required to enable
distribution of IPv6 multicast and anycast traffic on a shared link. Amendments to specific IPv6 multicast forwarding
mechanisms are out of the scope of the present document. However, the present document aims at not preventing
existing IPv6 multicast forwarding mechanisms from being used in conjunction with the GN6ASL.
In order to facilitate the deployment of ITS systems, the present document aims at maintaining backward compatibility
with pre-existent IPv6-compliant protocol implementations and NEMO BS implementations compliant with [15]. An
exemplary usage of NEMO BS with the GN6ASL is overviewed in the informative annex F.
The present document does not request any assignment or reservation of IPv6 prefixes or suffixes for specific purposes.
The mechanisms specified in the present document are distinct from but compatible with the IPv6-related functionalities
in [i.24], which specifies how IPv6 networking is generally operated in ITS stations. The techniques described in the
present document provide a way to transport IPv6 packets that is fully compatible with the IPv6 specifications and
pre-existing implementations, and hence is compatible with [i.19].
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9 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbo0x.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 302 665: "Intelligent Transport Systems (ITS); Communications Architecture".
[2] ETSI ES 202 663: "Intelligent Transport Systems (ITS); European profile standard for the physical
and medium access control layer of Intelligent Transport Systems operating in the 5 GHz
frequency band".
[3] ETSI TS 102 636-1: "Intelligent Transport Systems (ITS); Vehicular Communications;
GeoNetworking; Part 1: Requirements".
[4] ETSI TS 102 636-2: "Intelligent Transport Systems (ITS); Vehicular Communications;
GeoNetworking; Part 2: Scenarios".
[5] ETSI TS 102 636-3: "Intelligent Transport Systems (ITS); Vehicular Communications;
GeoNetworking; Part 3: Network architecture".
[6] ETSI EN 302 931: "Intelligent Transport Systems (ITS); Vehicular Communications;
Geographical Area Definition".
[7] IETF RFC 2460: "Internet Protocol, Version 6 (IPv6) Specification".
[8] IETF RFC 4291: "IP Version 6 (IPv6) Addressing Architecture".
[9] IETF RFC 4007: "IPv6 Scoped Address Architecture".
[10] IETF RFC 4861: "Neighbor Discovery for IP version 6 (IPv6)".
[11] IETF RFC 5942: "IPv6 Subnet Model: The Relationship between Links and Subnet Prefixes".
[12] IETF RFC 4862: "IPv6 Stateless Address Autoconfiguration".
[13] IETF RFC 3753: "Mobility Related Terminology".
[14] IETF RFC 4885: "Network Mobility Support Terminology".
[15] IETF RFC 3963: "Network Mobility (NEMO) Basic Support Protocol".
[16] IETF RFC 3484: "Default Address Selection for Internet Protocol version 6 (IPv6)".
[17] IETF RFC 2464: "Transmission of IPv6 Packets over Ethernet Networks".
[18] IETF RFC 2491: "IPv6 over Non-Broadcast Multiple Access (NBMA) networks".
[19] IETF RFC 2472: "IP Version 6 over PPP".
[20] IETF RFC 3810: "Multicast Listener Discovery Version 2 (MLDv2) for IPv6".
[21] IETF RFC 4601: "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol
Specification (Revised)".
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10 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
[22] IETF RFC 4605: "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery
(MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")".
[23] IETF RFC 3306: "Unicast-Prefix-based IPv6 Multicast Addresses".
[24] IETF RFC 2022: "Support for Multicast over UNI 3.0/3.1 based ATM Networks".
[25] IETF RFC 1042: "A Standard for the Transmission of IP Datagrams over IEEE 802 Networks".
[26] IETF RFC 3971: "SEcure Neighbor Discovery (SEND)".
[27] IETF RFC 4293: "Management Information Base for the Internet Protocol (IP)".
[28] ISO/IEC 8802-2:1998: "Information technology-Telecommunications and information exchange
between systems-Local and metropolitan area networks-Specific requirements-Part 2: Logical link
control".
[29] ISO/IEC 15802-3: "Information Technology-Telecommunications and information exchange
between systems-Local and metropolitan area networks-Common specifications-Part 3: Media
Access Control (MAC) Bridges" (previously known as IEEE Std 802.1D-1998).
[30] IEEE 802.11:2007: "IEEE Standard for Information Technology - Telecommunications and
Information Exchange Between Systems-Local and Metropolitan Area Networks - Specific
Requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications".
[31] IEEE 802.1Q:1998: "IEEE Standards for Local and Metropolitan Area Networks: Virtual Bridged
Local Area Networks".
[32] IEEE 802.3:2005: "IEEE Standard for Information Technology - Telecommunications and
information exchange between systems-Local and metropolitan area networks - Specific
requirements - Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
Access Method and Physical Layer Specifications".
[33] IEEE "Guidelines For 64-bit Global Identifier (EUI-64)".
NOTE: Available at: http://standards.ieee.org/regauth/oui/tutorials/EUI64.html.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] IETF RFC 4294: "IPv6 Node Requirements".
[i.2] IETF RFC 4903: "Multi-Link Subnet Issues".
[i.3] IETF RFC 4840: "Multiple Encapsulation Methods Considered Harmful".
[i.4] IETF RFC 3316: "Internet Protocol Version 6 (IPv6) for Some Second and Third Generation
Cellular Hosts".
[i.5] IETF RFC 5154: "IP over IEEE 802.16 Problem Statement and Goals".
[i.6] IETF RFC 3549: "Linux Netlink as an IP Services Protocol".
[i.7] IETF RFC 3314: "Recommendations for IPv6 in Third Generation Partnership Project (3GPP)
Standards".
[i.8] IETF RFC 1661: "The Point-to-Point Protocol (PPP)".
[i.9] IETF RFC 1902: "Structure of Management Information for Version 2 of the Simple Network
Management Protocol (SNMPv2)". Textual Conventions for SMIv2.
[i.10] IETF RFC 2579: "Textual Conventions for SMIv2".
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11 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
[i.11] IETF draft: "6LoWPAN Neighbor Discovery", draft-ietf-6lowpan-nd-14, September 2009, work in
progress.
[i.12] ETSI TR 102 893: "Intelligent Transport Systems (ITS); Security; Threat, Vulnerability and Risk
Analysis (TVRA)".
[i.13] ETSI TS 102 731: "Intelligent Transport Systems (ITS); Security; Security Services and
Architecture".
[i.14] ETSI TS 102 637-2: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set
of Applications; Part 2: Specification of Cooperative Awareness Basic Service".
[i.15] Universal TUN/TAP driver for Linux, Solaris and FreeBSD.
NOTE: Available at: http://vtun.sourceforge.net/tun/index.html.
[i.16] FP7 STREP N 216269 European Project GeoNet - Geographic addressing and routing for
vehicular communications - Deliverable D1.2 v1.1: "Final GeoNet Architecture Design".
[i.17] FP7 STREP N 216269 European Project GeoNet - Geographic addressing and routing for
vehicular communications - Deliverable D2.2 v1.1: "Specification - Final Release".
[i.18] FP7 STREP N 216269 European Project GeoNet - Geographic addressing and routing for
vehicular communications - Deliverable D7.1 v1.0: "GeoNet Experimentation Results".
[i.19] ISO 21210-2010: "Intelligent Transport Systems - Communications access for land mobiles
(CALM) - IPv6 networking".
[i.20] IETF draft-ietf-mext-nemo-ro-automotive-req-02 (July 2009): "Automotive Industry Requirements
for NEMO Route Optimization", (work in progress).
[i.21] ETSI TS 123 060: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); General Packet Radio Service (GPRS); Service
description; Stage 2 (3GPP TS 23.060 Release 9)".
[i.22] R. Baldessari, C. J. Bernardos, M. Calderon, GeoSAC - Scalable Address Autoconfiguration for
VANET Using Geographic Networking Concepts, IEEE PIMRC 2008, The 19th IEEE
International Symposium on Personal, Indoor and Mobile Radio Communications, Cannes,
France, Sept. 2008.
[i.23] C. Harsch, A. Festag, P. Papadimitratos, Secure Position-Based Routing for VANETs, IEEE VTC
2007 Fall, The 66th IEEE Vehicular Technology Conference, Baltimore, USA, Oct. 2007.
[i.24] ISO/IEC Technical Report 11802-5:1997(E): "Information technology-Telecommunications and
information exchange between systems-Local and metropolitan area networks-Technical reports
and guidelines-Part 5: Medium Access Control (MAC) Bridging of Ethernet V2.0 in Local Area
Networks" (previously known as IEEE Std 802.1H-1997).
[i.25] ETSI TS 102 636-4-1: "Intelligent Transport System (ITS); Vehicular communications;
GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and point-to-
multipoint communications; Sub-part 1: Media independent functionalities".
[i.26] ETSI TS 102 636-4-2: "Intelligent Transport Systems (ITS); Vehicular Communications;
GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and point-to-
multipoint communications; Sub-part 2: Media dependent functionalities for ITS-G5A media".
[i.27] ETSI TS 102 723-10: "Intelligent Transport Systems; OSI cross-layer topics; Part 10: Interface
between access layer and network and transport layers".
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12 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in [1], [5], [10], [13], [14] and the following
apply:
Geographical Virtual Link: link-local multicast-capable virtual link spanning multiple physical links with
geographically scoped boundaries
GN6 Adaptation Sub-Layer: protocol adaptation sub-layer supporting the transmission of IPv6 packets over
GeoNetworking
GVL Area: geographical area associated to a GVL
IPv6-compliant: compliant with [7], [8], [9], [10] and [12]
sub-IP multi-hop delivery: IP packet delivery traversing several ITS stations where the Hop Limit field of the IPv6
header [7] is not decreased
Topological Virtual Link: Non-Broadcast Multi-Access (NBMA) virtual link spanning multiple physical links with
topologically scoped boundaries
3.2 Symbols
For the purposes of the present document, the following symbols apply:
GEO Size of the largest GeoNetworking header
MAX
GEOSEC Size of the largest optional GeoNetworking security header
MAX
MTU Maximum transmission unit offered by the protocol layer below GeoNetworking
AL
MTU Maximum transmission unit offered by GN6ASL to IPv6
GN6
MTU Typical maximum transmission unit associated to the type of a virtual interface
VI
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ASL Adaptation Sub-Layer
CGA Cryptographically Generated Addresses
GN6 GeoNetworking-IPv6
GN6ASL GeoNetworking-IPv6 Adaptation Sub-Layer
GN6SDU GN6 Service Data Unit
GPRS General Packet Radio Service
GVL Geographical Virtual Link
IID Interface Identifier
IP Internet Protocol
ITS Intelligent Transport System
LAN Local Area Network
LLC Logical Link Control
MAC Media Access Control
MIB Managed Information Base
MTU Maximum Transmission Unit
NA Neighbor Advertisement
NBMA Non-Broadcast Multiple Access
ND Neighbor Discovery
NEMO BS NEtwork MObility Basic Support
NH Next Header
NS Neighbor Solicitation
NUD Neighbor Unreachability Detection
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13 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
PDCP Packet Data Convergence Protocol
PHY PHYsical
PPP Point-to-Point Protocol
RA Router Advertissement
SAP Service Access Point
SEND SEcure Neighbor Discovery
SLAAC StateLess Address AutoConfiguration
SMI Structure of Management Information
SNAP SubNetwork Access Protocol
STA STAtion
TAP Terminal Access Point
TCP Transmission Control Protocol
TUN network TUNnel
TVL Topological Virtual Link
UDP User Datagram Protocol
UMTS Universal Mobile Telecommunications Systems
VC Virtual Circuit
4 GN6ASL in the ITS station architecture
With respect to the ITS station reference architecture [1], the present document only affects the layer block
"Networking and Transport". As depicted in figure 1, within the layer block "Networking and Transport", the present
document introduces GN6ASL, an adaptation sub-layer for the transmission of IPv6 packets over GeoNetworking. The
other protocols depicted in figure 1 (e.g. TCP and UDP) are represented for sake of completeness in order to represent a
typical usage of the present document.

Figure 1: GN6ASL in the ITS station architecture
As depicted in figure 1, the present document builds an adaptation sub-layer (GN6ASL) between the ETSI
GeoNetworking protocol [i.25] and an IPv6-compliant protocol layer and extended with mobility extensions. The
default IPv6 mobility extensions in the ETSI ITS architecture [1] (as well as in [i.19]) is the Network Mobility Basic
Support (NEMO BS) protocol [15]. The present document enables the usage of NEMO BS over the ETSI
GeoNetworking protocol [i.25].
NOTE: With respect to the figure 1, the scope of [i.19] includes the protocol layer IPv6 + Mobility Extensions,
directly above the adaptation sub-layer specified in the present document.
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14 ETSI TS 102 636-6-1 V1.1.1 (2011-03)
5 IPv6 link models and interfaces
5.1 Rationales
The Neighbor Discovery (ND) protocol [10] is a mandatory part of IPv6 stacks that includes functionalities like Router
and Prefix Discovery as well as Address Resolution and Neighbor Unreachability Detection. Some of ND's services use
link-layer multicast addresses. This implies that the link-layer protocol is required to support multicast addressing in
order to run the ND protocol as described in [10]. ND adaptations or alternative protocols or mechanisms to implement
its services are commonly introduced for link-layer technologies that do not support multicast addressing
(e.g. [18], [i.4], [i.5]).
GN6ASL is presented to the IPv6 layer as a link-layer protocol which relies on GeoNetworking [i.25]. GeoNetworking
provides both point-to-point and point-to-multipoint communications, as well as geographically scoped addressing like
GeoAnycast and GeoBroadcast [4]. Furthermore, [i.25] provides upper layers with a sub-IP multi-hop delivery service
as required by [3].
NOTE: "sub-IP multi-hop delivery" is defined in clause 3.1.
When IPv6 makes use of the sub-IP multi-hop delivery service provided by ETSI GeoNetworking protocol [i.25] via
GN6ASL, virtual links are used that span multiple physical links. These virtual links are modelled and characterized in
the present document such that they can be utilized by an IPv6-compliant protocol layer. In particular, link-layer
multicast support in a virtual link that spans multiple physical links requires symmetric reachability (defined in [10]) be
satisfied by the virtual link. Virtual links for mobile ad-hoc networks that define the virtual link's boundary based on the
number of hops do not provide symmetric reachability in mobile environments due to the changing network topology.
GN6ASL provides virtual links that present symmetric reachability, since the virtual links' boundaries are defined as
geographical coordinates.
The present document introduces two types of virtual link, one designed to be link-local multicast capable by means of
geographically scoped boundaries and the other one with no link-local multicast support but not subject to geographic
boundaries. The combination of these two types of virtual link in the same station allows running the ND protocol
including SLAAC [12] as well as to distribute other IPv6 link-local multicast traffic and, at the same time, to reach
nodes that are outside specific geographic boundaries. The two properties are split up in two different virtual link types
in order to maintain full compliance with the link properties required by ND.
EXAMPLE: In 3GPP Release 9, IPv6 is transported directly over PDCP, and optionally via PPP [i.21]. In both
cases, over PDCP and via PPP, virtual point-to-point links are used. [i.21] uses some ND
operations like the issuing of a Router Solicitation although, as pointed out in [i.7], the IETF has
not specified a point-to-point architecture and how the standard IPv6 address assignment
mechanisms are applicable to IPv6 over point-to-point links. [i.7] called for the (at that time still
existing) IPv6 WG to carry out these activities but to date no specification exists. Consequently,
whenever possible, it is recommended to provide link-local multicast capable virtual links, which
is achieved in the present document by means of a geographically scoped virtual link.
In the followings, virtual links are distinguished from virtual interfaces. A virtual interface represents an instance of a
virtual link that is presented to the IPv6 layer in an implementation-specific way. Compliance to the present document
is required for virtual links but not for virtual interfaces, being virtual interfaces an implementation-specific way to
provide virtual links. For this reason, the following sections distinguish between required and recommended properties.
However, the properties and usage of virtual interfaces as described in the present document maximize backward
compatibility with pre-existing IPv6-compliant implementations, such that these implementations can be used over
GN6ASL.
It should be noted that the specific virtual interface chosen by an implementation does not affect the encapsulation
method nor the link properties. Further, the emulation operated by a virtual interface shall maintain the link properties
(e.g. with respect to symmetri
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