draft-ietf-ipwave-ipv6-over-80211ocb-26.txt   draft-ietf-ipwave-ipv6-over-80211ocb-27.txt 
IPWAVE Working Group A. Petrescu IPWAVE Working Group A. Petrescu
Internet-Draft CEA, LIST Internet-Draft CEA, LIST
Intended status: Standards Track N. Benamar Intended status: Standards Track N. Benamar
Expires: March 11, 2019 Moulay Ismail University Expires: March 18, 2019 Moulay Ismail University
J. Haerri J. Haerri
Eurecom Eurecom
J. Lee J. Lee
Sangmyung University Sangmyung University
T. Ernst T. Ernst
YoGoKo YoGoKo
September 7, 2018 September 14, 2018
Transmission of IPv6 Packets over IEEE 802.11 Networks operating in mode Transmission of IPv6 Packets over IEEE 802.11 Networks operating in mode
Outside the Context of a Basic Service Set (IPv6-over-80211-OCB) Outside the Context of a Basic Service Set (IPv6-over-80211-OCB)
draft-ietf-ipwave-ipv6-over-80211ocb-26 draft-ietf-ipwave-ipv6-over-80211ocb-27
Abstract Abstract
In order to transmit IPv6 packets on IEEE 802.11 networks running In order to transmit IPv6 packets on IEEE 802.11 networks running
outside the context of a basic service set (OCB, earlier "802.11p") outside the context of a basic service set (OCB, earlier "802.11p")
there is a need to define a few parameters such as the supported there is a need to define a few parameters such as the supported
Maximum Transmission Unit size on the 802.11-OCB link, the header Maximum Transmission Unit size on the 802.11-OCB link, the header
format preceding the IPv6 header, the Type value within it, and format preceding the IPv6 header, the Type value within it, and
others. This document describes these parameters for IPv6 and IEEE others. This document describes these parameters for IPv6 and IEEE
802.11-OCB networks; it portrays the layering of IPv6 on 802.11-OCB 802.11-OCB networks; it portrays the layering of IPv6 on 802.11-OCB
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 11, 2019. This Internet-Draft will expire on March 18, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Communication Scenarios where IEEE 802.11-OCB Links are Used 4 3. Communication Scenarios where IEEE 802.11-OCB Links are Used 4
4. IPv6 over 802.11-OCB . . . . . . . . . . . . . . . . . . . . 5 4. IPv6 over 802.11-OCB . . . . . . . . . . . . . . . . . . . . 4
4.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 5 4.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 5
4.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 5 4.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 5
4.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 5 4.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 5
4.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 7 4.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 7
4.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 7 4.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 7
4.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 7 4.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 7
4.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 7 4.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 7
4.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 7 4.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 7
4.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 8 4.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
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9.1. Normative References . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 15 Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 15
Appendix B. 802.11p . . . . . . . . . . . . . . . . . . . . . . 24 Appendix B. 802.11p . . . . . . . . . . . . . . . . . . . . . . 24
Appendix C. Aspects introduced by the OCB mode to 802.11 . . . . 24 Appendix C. Aspects introduced by the OCB mode to 802.11 . . . . 24
Appendix D. Changes Needed on a software driver 802.11a to Appendix D. Changes Needed on a software driver 802.11a to
become a 802.11-OCB driver . . . 28 become a 802.11-OCB driver . . . 28
Appendix E. EtherType Protocol Discrimination (EPD) . . . . . . 29 Appendix E. EtherType Protocol Discrimination (EPD) . . . . . . 29
Appendix F. Design Considerations . . . . . . . . . . . . . . . 30 Appendix F. Design Considerations . . . . . . . . . . . . . . . 30
F.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 30 F.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 30
F.2. Reliability Requirements . . . . . . . . . . . . . . . . 31 Appendix G. IEEE 802.11 Messages Transmitted in OCB mode . . . . 31
F.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 31 Appendix H. Examples of Packet Formats . . . . . . . . . . . . . 31
Appendix G. IEEE 802.11 Messages Transmitted in OCB mode . . . . 32 H.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 32
Appendix H. Examples of Packet Formats . . . . . . . . . . . . . 32 H.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 34
H.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 33 Appendix I. Extra Terminology . . . . . . . . . . . . . . . . . 36
H.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
Appendix I. Extra Terminology . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39
1. Introduction 1. Introduction
This document describes the transmission of IPv6 packets on IEEE Std This document describes the transmission of IPv6 packets on IEEE Std
802.11-OCB networks [IEEE-802.11-2016] (a.k.a "802.11p" see 802.11-OCB networks [IEEE-802.11-2016] (a.k.a "802.11p" see
Appendix B, Appendix C and Appendix D). This involves the layering Appendix B, Appendix C and Appendix D). This involves the layering
of IPv6 networking on top of the IEEE 802.11 MAC layer, with an LLC of IPv6 networking on top of the IEEE 802.11 MAC layer, with an LLC
layer. Compared to running IPv6 over the Ethernet MAC layer, there layer. Compared to running IPv6 over the Ethernet MAC layer, there
is no modification expected to IEEE Std 802.11 MAC and Logical Link is no modification expected to IEEE Std 802.11 MAC and Logical Link
sublayers: IPv6 works fine directly over 802.11-OCB too, with an LLC sublayers: IPv6 works fine directly over 802.11-OCB too, with an LLC
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
IP-OBU (Internet Protocol On-Board Unit): an IP-OBU is a computer IP-OBU (Internet Protocol On-Board Unit): an IP-OBU is a computer
situated in a vehicle such as an automobile, bicycle, or similar. It situated in a vehicle such as an automobile, bicycle, or similar. It
has at least one IP interface that runs in mode OCB of 802.11, and has at least one IP interface that runs in mode OCB of 802.11, and
that has an "OBU" transceiver. See the definition of the term "OBU" that has an "OBU" transceiver. See the definition of the term "OBU"
in section Appendix I. in section Appendix I.
IP-RSU (IP Road-Side Unit): an IP-RSU is situated along the road. An IP-RSU (IP Road-Side Unit): an IP-RSU is situated along the road. An
IP-RSU has at least two distinct IP-enabled interfaces; at least one IP-RSU has at least two distinct IP-enabled interfaces. An IP-RSU is
interface is operated in mode OCB of IEEE 802.11 and is IP-enabled. similar to a Wireless Termination Point (WTP), as defined in
An IP-RSU is similar to a Wireless Termination Point (WTP), as [RFC5415], or an Access Point (AP), as defined in IEEE documents, or
defined in [RFC5415], or an Access Point (AP), as defined in IEEE an Access Network Router (ANR) defined in [RFC3753], with one key
documents, or an Access Network Router (ANR) defined in [RFC3753], particularity: the wireless PHY/MAC layer of at least one of its IP-
with one key particularity: the wireless PHY/MAC layer of at least enabled interfaces is configured to operate in 802.11-OCB mode. The
one of its IP-enabled interfaces is configured to operate in IP-RSU communicates with the IP-OBU in the vehicle over 802.11
802.11-OCB mode. The IP-RSU communicates with the IP-OBU in the wireless link operating in OCB mode.
vehicle over 802.11 wireless link operating in OCB mode.
OCB (outside the context of a basic service set - BSS): A mode of OCB (outside the context of a basic service set - BSS): A mode of
operation in which a STA is not a member of a BSS and does not operation in which a STA is not a member of a BSS and does not
utilize IEEE Std 802.11 authentication, association, or data utilize IEEE Std 802.11 authentication, association, or data
confidentiality. confidentiality.
802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB 802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB
attribute dot11OCBActivited is true. Note: compliance with standards attribute dot11OCBActivited is true. Note: compliance with standards
and regulations set in different countries when using the 5.9GHz and regulations set in different countries when using the 5.9GHz
frequency band is required. frequency band is required.
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802.11-OCB does not provide any cryptographic protection, because it 802.11-OCB does not provide any cryptographic protection, because it
operates outside the context of a BSS (no Association Request/ operates outside the context of a BSS (no Association Request/
Response, no Challenge messages). Any attacker can therefore just Response, no Challenge messages). Any attacker can therefore just
sit in the near range of vehicles, sniff the network (just set the sit in the near range of vehicles, sniff the network (just set the
interface card's frequency to the proper range) and perform attacks interface card's frequency to the proper range) and perform attacks
without needing to physically break any wall. Such a link is less without needing to physically break any wall. Such a link is less
protected than commonly used links (wired link or protected 802.11). protected than commonly used links (wired link or protected 802.11).
The potential attack vectors are: MAC address spoofing, IP address The potential attack vectors are: MAC address spoofing, IP address
and session hijacking and privacy violation. and session hijacking, and privacy violation Section 5.1.
Within the IPsec Security Architecture [RFC4301], the IPsec AH and Within the IPsec Security Architecture [RFC4301], the IPsec AH and
ESP headers [RFC4302] and [RFC4303] respectively, its multicast ESP headers [RFC4302] and [RFC4303] respectively, its multicast
extensions [RFC5374], HTTPS [RFC2818] and SeND [RFC3971] protocols extensions [RFC5374], HTTPS [RFC2818] and SeND [RFC3971] protocols
can be used to protect communications. Further, the assistance of can be used to protect communications. Further, the assistance of
proper Public Key Infrastructure (PKI) protocols [RFC4210] is proper Public Key Infrastructure (PKI) protocols [RFC4210] is
necessary to establish credentials. More IETF protocols are necessary to establish credentials. More IETF protocols are
available in the toolbox of the IP security protocol designer. available in the toolbox of the IP security protocol designer.
Certain ETSI protocols related to security protocols in Intelligent Certain ETSI protocols related to security protocols in Intelligent
Transportation Systems are described in [ETSI-sec-archi]. Transportation Systems are described in [ETSI-sec-archi].
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address spoofing and IP address hijacking risks. A vehicle embarking address spoofing and IP address hijacking risks. A vehicle embarking
an IP-OBU whose egress interface is 802.11-OCB may expose itself to an IP-OBU whose egress interface is 802.11-OCB may expose itself to
eavesdropping and subsequent correlation of data; this may reveal eavesdropping and subsequent correlation of data; this may reveal
data considered private by the vehicle owner; there is a risk of data considered private by the vehicle owner; there is a risk of
being tracked. In outdoors public environments, where vehicles being tracked. In outdoors public environments, where vehicles
typically circulate, the privacy risks are more important than in typically circulate, the privacy risks are more important than in
indoors settings. It is highly likely that attacker sniffers are indoors settings. It is highly likely that attacker sniffers are
deployed along routes which listen for IEEE frames, including IP deployed along routes which listen for IEEE frames, including IP
packets, of vehicles passing by. For this reason, in the 802.11-OCB packets, of vehicles passing by. For this reason, in the 802.11-OCB
deployments, there is a strong necessity to use protection tools such deployments, there is a strong necessity to use protection tools such
as dynamically changing MAC addresses. This may help mitigate as dynamically changing MAC addresses Section 5.2, semantically
privacy risks to a certain level. opaque Interface Identifiers and stable Interface Identifiers
Section 4.5. This may help mitigate privacy risks to a certain
level.
5.2. MAC Address Generation 5.2. MAC Address Generation
In 802.11-OCB networks, the MAC addresses MAY change during well In 802.11-OCB networks, the MAC addresses MAY change during well
defined renumbering events. In the moment the MAC address is changed defined renumbering events. In the moment the MAC address is changed
on an 802.11-OCB interface all the Interface Identifiers of IPv6 on an 802.11-OCB interface all the Interface Identifiers of IPv6
addresses assigned to that interface MUST change. addresses assigned to that interface MUST change.
The policy dictating when the MAC address is changed on the The policy dictating when the MAC address is changed on the
802.11-OCB interface is to-be-determined. For more information on 802.11-OCB interface is to-be-determined. For more information on
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draft-perkins-intarea-multicast-ieee802-03 (work in draft-perkins-intarea-multicast-ieee802-03 (work in
progress), July 2017. progress), July 2017.
[IEEE-1609.2] [IEEE-1609.2]
"IEEE SA - 1609.2-2016 - IEEE Standard for Wireless Access "IEEE SA - 1609.2-2016 - IEEE Standard for Wireless Access
in Vehicular Environments (WAVE) -- Security Services for in Vehicular Environments (WAVE) -- Security Services for
Applications and Management Messages. Example URL Applications and Management Messages. Example URL
http://ieeexplore.ieee.org/document/7426684/ accessed on http://ieeexplore.ieee.org/document/7426684/ accessed on
August 17th, 2017.". August 17th, 2017.".
[IEEE-1609.3]
"IEEE SA - 1609.3-2016 - IEEE Standard for Wireless Access
in Vehicular Environments (WAVE) -- Networking Services.
Example URL http://ieeexplore.ieee.org/document/7458115/
accessed on August 17th, 2017.".
[IEEE-1609.4]
"IEEE SA - 1609.4-2016 - IEEE Standard for Wireless Access
in Vehicular Environments (WAVE) -- Multi-Channel
Operation. Example URL
http://ieeexplore.ieee.org/document/7435228/ accessed on
August 17th, 2017.".
[IEEE-802.11-2016] [IEEE-802.11-2016]
"IEEE Standard 802.11-2016 - IEEE Standard for Information "IEEE Standard 802.11-2016 - IEEE Standard for Information
Technology - Telecommunications and information exchange Technology - Telecommunications and information exchange
between systems Local and metropolitan area networks - between systems Local and metropolitan area networks -
Specific requirements - Part 11: Wireless LAN Medium Specific requirements - Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) Access Control (MAC) and Physical Layer (PHY)
Specifications. Status - Active Standard. Description Specifications. Status - Active Standard. Description
retrieved freely on September 12th, 2017, at URL retrieved freely on September 12th, 2017, at URL
https://standards.ieee.org/findstds/ https://standards.ieee.org/findstds/
standard/802.11-2016.html". standard/802.11-2016.html".
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document freely available at URL document freely available at URL
http://standards.ieee.org/getieee802/ http://standards.ieee.org/getieee802/
download/802.11p-2010.pdf retrieved on September 20th, download/802.11p-2010.pdf retrieved on September 20th,
2013.". 2013.".
Appendix A. ChangeLog Appendix A. ChangeLog
The changes are listed in reverse chronological order, most recent The changes are listed in reverse chronological order, most recent
changes appearing at the top of the list. changes appearing at the top of the list.
-27: part 1 of addressing Human Rights review from IRTF. Removed
appendices F.2 and F.3. Shortened definition of IP-RSU. Removed
reference to 1609.4. A few other small changes, see diff.
-26: moved text from SLAAC section and from Design Considerations -26: moved text from SLAAC section and from Design Considerations
appendix about privacy into a new Privacy Condiderations subsection appendix about privacy into a new Privacy Condiderations subsection
of the Security section; reformulated the SLAAC and IID sections to of the Security section; reformulated the SLAAC and IID sections to
stress only LLs can use EUI-64; removed the "GeoIP" wireshark stress only LLs can use EUI-64; removed the "GeoIP" wireshark
explanation; reformulated SLAAC and LL sections; added brief mention explanation; reformulated SLAAC and LL sections; added brief mention
of need of use LLs; clarified text about MAC address changes; dropped of need of use LLs; clarified text about MAC address changes; dropped
pseudonym discussion; changed title of section describing examples of pseudonym discussion; changed title of section describing examples of
packet formats. packet formats.
-25: added a reference to 'IEEE Management Information Base', instead -25: added a reference to 'IEEE Management Information Base', instead
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related to PHY, and thus has not much impact on the interface related to PHY, and thus has not much impact on the interface
between the IP layer and the MAC layer. between the IP layer and the MAC layer.
o In vehicular communications using 802.11-OCB links, there are o In vehicular communications using 802.11-OCB links, there are
strong privacy requirements with respect to addressing. While the strong privacy requirements with respect to addressing. While the
802.11-OCB standard does not specify anything in particular with 802.11-OCB standard does not specify anything in particular with
respect to MAC addresses, in these settings there exists a strong respect to MAC addresses, in these settings there exists a strong
need for dynamic change of these addresses (as opposed to the non- need for dynamic change of these addresses (as opposed to the non-
vehicular settings - real wall protection - where fixed MAC vehicular settings - real wall protection - where fixed MAC
addresses do not currently pose some privacy risks). This is addresses do not currently pose some privacy risks). This is
further described in Section 5. A relevant function is described further described in Section 5.
in IEEE 1609.3-2016 [IEEE-1609.3], clause 5.5.1 and IEEE
1609.4-2016 [IEEE-1609.4], clause 6.7.
Appendix D. Changes Needed on a software driver 802.11a to become a Appendix D. Changes Needed on a software driver 802.11a to become a
802.11-OCB driver 802.11-OCB driver
The 802.11p amendment modifies both the 802.11 stack's physical and The 802.11p amendment modifies both the 802.11 stack's physical and
MAC layers but all the induced modifications can be quite easily MAC layers but all the induced modifications can be quite easily
obtained by modifying an existing 802.11a ad-hoc stack. obtained by modifying an existing 802.11a ad-hoc stack.
Conditions for a 802.11a hardware to be 802.11-OCB compliant: Conditions for a 802.11a hardware to be 802.11-OCB compliant:
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In case multiple 802.11-OCB NICs are present in one car, implicitely In case multiple 802.11-OCB NICs are present in one car, implicitely
multiple vehicle IDs will be generated. Additionally, some software multiple vehicle IDs will be generated. Additionally, some software
generates a random MAC address each time the computer boots; this generates a random MAC address each time the computer boots; this
constitutes an additional difficulty. constitutes an additional difficulty.
A mechanim to uniquely identify a vehicle irrespectively to the A mechanim to uniquely identify a vehicle irrespectively to the
multiplicity of NICs, or frequent MAC address generation, is multiplicity of NICs, or frequent MAC address generation, is
necessary. necessary.
F.2. Reliability Requirements
The dynamically changing topology, short connectivity, mobile
transmitter and receivers, different antenna heights, and many-to-
many communication types, make IEEE 802.11-OCB links significantly
different from other IEEE 802.11 links. Any IPv6 mechanism operating
on IEEE 802.11-OCB link must support strong link asymmetry, spatio-
temporal link quality, fast address resolution and transmission.
IEEE 802.11-OCB strongly differs from other 802.11 systems to operate
outside of the context of a Basic Service Set. This means in
practice that IEEE 802.11-OCB does not rely on a Base Station for all
Basic Service Set management. In particular, IEEE 802.11-OCB shall
not use beacons. Any IPv6 mechanism requiring L2 services from IEEE
802.11 beacons must support an alternative service.
Channel scanning being disabled, IPv6 over IEEE 802.11-OCB must
implement a mechanism for transmitter and receiver to converge to a
common channel.
Authentication not being possible, IPv6 over IEEE 802.11-OCB must
implement an distributed mechanism to authenticate transmitters and
receivers without the support of a DHCP server.
Time synchronization not being available, IPv6 over IEEE 802.11-OCB
must implement a higher layer mechanism for time synchronization
between transmitters and receivers without the support of a NTP
server.
The IEEE 802.11-OCB link being asymmetric, IPv6 over IEEE 802.11-OCB
must disable management mechanisms requesting acknowledgements or
replies.
The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE
802.11-OCB should implement fast IPv6 mobility management mechanisms.
F.3. Multiple interfaces
There are considerations for 2 or more IEEE 802.11-OCB interface
cards per vehicle. For each vehicle taking part in road traffic, one
IEEE 802.11-OCB interface card could be fully allocated for Non IP
safety-critical communication. Any other IEEE 802.11-OCB may be used
for other type of traffic.
The mode of operation of these other wireless interfaces is not
clearly defined yet. One possibility is to consider each card as an
independent network interface, with a specific MAC Address and a set
of IPv6 addresses. Another possibility is to consider the set of
these wireless interfaces as a single network interface (not
including the IEEE 802.11-OCB interface used by Non IP safety
critical communications). This will require specific logic to
ensure, for example, that packets meant for a vehicle in front are
actually sent by the radio in the front, or that multiple copies of
the same packet received by multiple interfaces are treated as a
single packet. Treating each wireless interface as a separate
network interface pushes such issues to the application layer.
Certain privacy requirements imply that if these multiple interfaces
are represented by many network interface, a single renumbering event
shall cause renumbering of all these interfaces. If one MAC changed
and another stayed constant, external observers would be able to
correlate old and new values, and the privacy benefits of
randomization would be lost.
Appendix G. IEEE 802.11 Messages Transmitted in OCB mode Appendix G. IEEE 802.11 Messages Transmitted in OCB mode
For information, at the time of writing, this is the list of IEEE For information, at the time of writing, this is the list of IEEE
802.11 messages that may be transmitted in OCB mode, i.e. when 802.11 messages that may be transmitted in OCB mode, i.e. when
dot11OCBActivated is true in a STA: dot11OCBActivated is true in a STA:
o The STA may send management frames of subtype Action and, if the o The STA may send management frames of subtype Action and, if the
STA maintains a TSF Timer, subtype Timing Advertisement; STA maintains a TSF Timer, subtype Timing Advertisement;
o The STA may send control frames, except those of subtype PS-Poll, o The STA may send control frames, except those of subtype PS-Poll,
 End of changes. 13 change blocks. 
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