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Transmission of IPv6 Packets over IEEE 802.11 Networks operating in mode Outside the Context of a Basic Service Set (IPv6-over-80211-OCB)
draft-ietf-ipwave-ipv6-over-80211ocb-32

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8691.
Authors Alexandre Petrescu , Nabil Benamar , Jerome Haerri , Jong-Hyouk Lee , Thierry Ernst , Thierry Ernst
Last updated 2018-12-10
Replaces draft-petrescu-ipv6-over-80211p
RFC stream Internet Engineering Task Force (IETF)
Formats
Reviews
Additional resources Mailing list discussion
Stream WG state WG Consensus: Waiting for Write-Up
Other - see Comment Log
Document shepherd Carlos J. Bernardos
IESG IESG state Became RFC 8691 (Proposed Standard)
Consensus boilerplate Yes
Telechat date (None)
Responsible AD (None)
Send notices to Carlos Bernardos <cjbc@it.uc3m.es>
draft-ietf-ipwave-ipv6-over-80211ocb-32
IPWAVE Working Group                                         A. Petrescu
Internet-Draft                                                 CEA, LIST
Intended status: Standards Track                              N. Benamar
Expires: June 13, 2019                          Moulay Ismail University
                                                               J. Haerri
                                                                 Eurecom
                                                                  J. Lee
                                                    Sangmyung University
                                                                T. Ernst
                                                                  YoGoKo
                                                       December 10, 2018

Transmission of IPv6 Packets over IEEE 802.11 Networks operating in mode
    Outside the Context of a Basic Service Set (IPv6-over-80211-OCB)
                draft-ietf-ipwave-ipv6-over-80211ocb-32

Abstract

   In order to transmit IPv6 packets on IEEE 802.11 networks running
   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
   Maximum Transmission Unit size on the 802.11-OCB link, the header
   format preceding the IPv6 header, the Type value within it, and
   others.  This document describes these parameters for IPv6 and IEEE
   802.11-OCB networks; it portrays the layering of IPv6 on 802.11-OCB
   similarly to other known 802.11 and Ethernet layers - by using an
   Ethernet Adaptation Layer.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 13, 2019.

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Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Communication Scenarios where IEEE 802.11-OCB Links are Used    4
   4.  IPv6 over 802.11-OCB  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Pseudonym Handling  . . . . . . . . . . . . . . . . . . .   5
     4.2.  Maximum Transmission Unit (MTU) . . . . . . . . . . . . .   5
     4.3.  Frame Format  . . . . . . . . . . . . . . . . . . . . . .   5
       4.3.1.  Ethernet Adaptation Layer . . . . . . . . . . . . . .   6
     4.4.  Link-Local Addresses  . . . . . . . . . . . . . . . . . .   7
     4.5.  Address Mapping . . . . . . . . . . . . . . . . . . . . .   7
       4.5.1.  Address Mapping -- Unicast  . . . . . . . . . . . . .   7
       4.5.2.  Address Mapping -- Multicast  . . . . . . . . . . . .   8
     4.6.  Stateless Autoconfiguration . . . . . . . . . . . . . . .   8
     4.7.  Subnet Structure  . . . . . . . . . . . . . . . . . . . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     5.1.  Privacy Considerations  . . . . . . . . . . . . . . . . .  11
     5.2.  MAC Address and Interface ID Generation . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  ChangeLog  . . . . . . . . . . . . . . . . . . . . .  17
   Appendix B.  802.11p  . . . . . . . . . . . . . . . . . . . . . .  27
   Appendix C.  Aspects introduced by the OCB mode to 802.11 . . . .  27
   Appendix D.  Changes Needed on a software driver 802.11a to
                become a                     802.11-OCB driver . . .  31
   Appendix E.  Protocol Layering  . . . . . . . . . . . . . . . . .  32
   Appendix F.  Design Considerations  . . . . . . . . . . . . . . .  33
   Appendix G.  IEEE 802.11 Messages Transmitted in OCB mode . . . .  33

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   Appendix H.  Examples of Packet Formats . . . . . . . . . . . . .  34
     H.1.  Capture in Monitor Mode . . . . . . . . . . . . . . . . .  35
     H.2.  Capture in Normal Mode  . . . . . . . . . . . . . . . . .  37
   Appendix I.  Extra Terminology  . . . . . . . . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40

1.  Introduction

   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
   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
   layer.  Compared to running IPv6 over the Ethernet MAC layer, there
   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
   layer.

   The IPv6 network layer operates on 802.11-OCB in the same manner as
   operating on Ethernet, but there are two kinds of exceptions:

   o  Exceptions due to different operation of IPv6 network layer on
      802.11 than on Ethernet.  To satisfy these exceptions, this
      document describes an Ethernet Adaptation Layer between Ethernet
      headers and 802.11 headers.  The Ethernet Adaptation Layer is
      described Section 4.3.1.  The operation of IP on Ethernet is
      described in [RFC1042], [RFC2464] and
      [I-D.hinden-6man-rfc2464bis].

   o  Exceptions due to the OCB nature of 802.11-OCB compared to 802.11.
      This has impacts on security, privacy, subnet structure and
      handover behaviour.  For security and privacy recommendations see
      Section 5 and Section 4.6.  The subnet structure is described in
      Section 4.7.  The handover behaviour on OCB links is not described
      in this document.

   The Security Considerations section describes security and privacy
   aspects of 802.11-OCB.

   In the published literature, many documents describe aspects and
   problems related to running IPv6 over 802.11-OCB:
   [I-D.ietf-ipwave-vehicular-networking-survey].

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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   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
   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"
   in section Appendix I.

   IP-RSU (IP Road-Side Unit): an IP-RSU is situated along the road.  It
   has at least two distinct IP-enabled interfaces; the wireless PHY/MAC
   layer of at least one of its IP-enabled interfaces is configured to
   operate in 802.11-OCB mode.  An IP-RSU communicates with the IP-OBU
   in the vehicle over 802.11 wireless link operating in OCB mode.  An
   IP-RSU is similar to an Access Network Router (ANR) defined in
   [RFC3753], and a Wireless Termination Point (WTP) defined in
   [RFC5415].

   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
   utilize IEEE Std 802.11 authentication, association, or data
   confidentiality.

   802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB
   attribute dot11OCBActivited is true.  Note: compliance with standards
   and regulations set in different countries when using the 5.9GHz
   frequency band is required.

3.  Communication Scenarios where IEEE 802.11-OCB Links are Used

   The IEEE 802.11-OCB Networks are used for vehicular communications,
   as 'Wireless Access in Vehicular Environments'.  The IP communication
   scenarios for these environments have been described in several
   documents; in particular, we refer the reader to
   [I-D.ietf-ipwave-vehicular-networking-survey], that lists some
   scenarios and requirements for IP in Intelligent Transportation
   Systems.

   The link model is the following: STA --- 802.11-OCB --- STA.  In
   vehicular networks, STAs can be IP-RSUs and/or IP-OBUs.  While
   802.11-OCB is clearly specified, and the use of IPv6 over such link
   is not radically new, the operating environment (vehicular networks)
   brings in new perspectives.

   The mechanisms for forming and terminating, discovering, peering and
   mobility management for 802.11-OCB links are not described in this
   document.

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4.  IPv6 over 802.11-OCB

4.1.  Pseudonym Handling

   The demand for privacy protection of vehicles' and drivers'
   identities, which could be granted by using a pseudonym or alias
   identity at the same time, may hamper the required confidentiality of
   messages and trust between participants - especially in safety
   critical vehicular communication.

   o  Particular challenges arise when the pseudonymization mechanism
      used relies on (randomized) re-addressing.

   o  A proper pseudonymization tool operated by a trusted third party
      may be needed to ensure both aspects concurrently.

   o  This is discussed in Section 4.6 and Section 5.

   o  Pseudonymity is also discussed in
      [I-D.ietf-ipwave-vehicular-networking-survey] in sections 4.2.4
      and 5.1.2.

4.2.  Maximum Transmission Unit (MTU)

   The default MTU for IP packets on 802.11-OCB MUST be 1500 octets.  It
   is the same value as IPv6 packets on Ethernet links, as specified in
   [RFC2464].  This value of the MTU respects the recommendation that
   every link on the Internet must have a minimum MTU of 1280 octets
   (stated in [RFC8200], and the recommendations therein, especially
   with respect to fragmentation).

4.3.  Frame Format

   IP packets MUST be transmitted over 802.11-OCB media as QoS Data
   frames whose format is specified in IEEE Std 802.11.

   The IPv6 packet transmitted on 802.11-OCB MUST be immediately
   preceded by a Logical Link Control (LLC) header and an 802.11 header.
   In the LLC header, and in accordance with the EtherType Protocol
   Discrimination (EPD, see Appendix E), the value of the Type field
   MUST be set to 0x86DD (IPv6).  In the 802.11 header, the value of the
   Subtype sub-field in the Frame Control field MUST be set to 8 (i.e.
   'QoS Data'); the value of the Traffic Identifier (TID) sub-field of
   the QoS Control field of the 802.11 header MUST be set to binary 001
   (i.e.  User Priority 'Background', QoS Access Category 'AC_BK').

   To simplify the Application Programming Interface (API) between the
   operating system and the 802.11-OCB media, device drivers MAY

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   implement an Ethernet Adaptation Layer that translates Ethernet II
   frames to the 802.11 format and vice versa.  An Ethernet Adaptation
   Layer is described in Section 4.3.1.

4.3.1.  Ethernet Adaptation Layer

   An 'adaptation' layer is inserted between a MAC layer and the
   Networking layer.  This is used to transform some parameters between
   their form expected by the IP stack and the form provided by the MAC
   layer.

   An Ethernet Adaptation Layer makes an 802.11 MAC look to IP
   Networking layer as a more traditional Ethernet layer.  At reception,
   this layer takes as input the IEEE 802.11 header and the Logical-Link
   Layer Control Header and produces an Ethernet II Header.  At sending,
   the reverse operation is performed.

   The operation of the Ethernet Adaptation Layer is depicted by the
   double arrow in Figure 1.

   +------------------+------------+-------------+---------+-----------+
   |  802.11 header   | LLC Header | IPv6 Header | Payload |.11 Trailer|
   +------------------+------------+-------------+---------+-----------+
    \                             /                         \         /
      ---------------------------                             --------
                 \---------------------------------------------/
                           ^
                           |
              802.11-to-Ethernet Adaptation Layer
                           |
                           v
   +---------------------+-------------+---------+
   | Ethernet II Header  | IPv6 Header | Payload |
   +---------------------+-------------+---------+

           Figure 1: Operation of the Ethernet Adaptation Layer

   The Receiver and Transmitter Address fields in the 802.11 header MUST
   contain the same values as the Destination and the Source Address
   fields in the Ethernet II Header, respectively.  The value of the
   Type field in the LLC Header MUST be the same as the value of the
   Type field in the Ethernet II Header.  That value MUST be set to
   0x86DD (IPv6).

   The ".11 Trailer" contains solely a 4-byte Frame Check Sequence.

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   The placement of IPv6 networking layer on Ethernet Adaptation Layer
   is illustrated in Figure 2.

                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |                 IPv6                  |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |       Ethernet Adaptation Layer       |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |             802.11 MAC                |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |             802.11 PHY                |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 2: Ethernet Adaptation Layer stacked with other layers

   (in the above figure, a 802.11 profile is represented; this is used
   also for 802.11-OCB profile.)

4.4.  Link-Local Addresses

   There are several types of IPv6 addresses [RFC4291], [RFC4193], that
   MAY be assigned to an 802.11-OCB interface.  Among these types of
   addresses only the IPv6 link-local addresses MAY be formed using an
   EUI-64 identifier.

   If the IPv6 link-local address is formed using an EUI-64 identifier,
   then the mechanism of forming that address is the same mechanism as
   used to form an IPv6 link-local address on Ethernet links.  This
   mechanism is described in section 5 of [RFC2464].

   For privacy, the link-local address MAY be formed according to the
   mechanisms described in Section 5.2.

4.5.  Address Mapping

   Unicast and multicast address mapping MUST follow the procedures
   specified for Ethernet interfaces in sections 6 and 7 of [RFC2464].

4.5.1.  Address Mapping -- Unicast

   The procedure for mapping IPv6 unicast addresses into Ethernet link-
   layer addresses is described in [RFC4861].

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4.5.2.  Address Mapping -- Multicast

   The multicast address mapping is performed according to the method
   specified in section 7 of [RFC2464].  The meaning of the value "3333"
   mentioned in that section 7 of [RFC2464] is defined in section 2.3.1
   of [RFC7042].

   Transmitting IPv6 packets to multicast destinations over 802.11 links
   proved to have some performance issues
   [I-D.perkins-intarea-multicast-ieee802].  These issues may be
   exacerbated in OCB mode.  Solutions for these problems should
   consider the OCB mode of operation.

4.6.  Stateless Autoconfiguration

   There are several types of IPv6 addresses [RFC4291], [RFC4193], that
   MAY be assigned to an 802.11-OCB interface.  This section describes
   the formation of Interface Identifiers for IPv6 addresses of type
   'Global' or 'Unique Local'.  For Interface Identifiers for IPv6
   address of type 'Link-Local' see Section 4.4.

   The Interface Identifier for an 802.11-OCB interface is formed using
   the same rules as the Interface Identifier for an Ethernet interface;
   the RECOMMENDED method for forming stable Interface Identifiers
   (IIDs) is described in [RFC8064].  The method of forming IIDs
   described in section 4 of [RFC2464] MAY be used during transition
   time.

   The bits in the Interface Identifier have no generic meaning and the
   identifier should be treated as an opaque value.  The bits
   'Universal' and 'Group' in the identifier of an 802.11-OCB interface
   are significant, as this is an IEEE link-layer address.  The details
   of this significance are described in [RFC7136].  If semantically
   opaque Interface Identifiers are needed, a potential method for
   generating semantically opaque Interface Identifiers with IPv6
   Stateless Address Autoconfiguration is given in [RFC7217].

   Semantically opaque Interface Identifiers, instead of meaningful
   Interface Identifiers derived from a valid and meaningful MAC address
   ([RFC2464], section 4), MAY be needed in order to avoid certain
   privacy risks.

   A valid MAC address includes a unique identifier pointing to a
   company together with its postal address, and a unique number within
   that company MAC space (see the oui.txt file).  The calculation
   operation of the MAC address back from a given meaningful Interface
   Identifier is straightforward ([RFC2464], section 4).  The Interface
   Identifier is part of an IPv6 address that is stored in IPv6 packets.

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   The IPv6 packets can be captured in the Internet easily.  For these
   reasons, an attacker may realize many attacks on privacy.  One such
   attack on 802.11-OCB is to capture, store and correlate Company ID
   information of many cars in public areas (e.g. listen for Router
   Advertisements, or other IPv6 application data packets, and record
   the value of the source address in these packets).  Further
   correlation of this information with other data captured by other
   means, or other visual information (car color, others) MAY constitute
   privacy risks.

   In order to avoid these risks, opaque Interface Identifiers MAY be
   formed according to rules described in [RFC7217].  These opaque
   Interface Identifiers are formed starting from identifiers different
   than the MAC addresses, and from cryptographically strong material.
   Thus, privacy sensitive information is absent from Interface IDs, and
   it is impossible to calculate the initial value from which the
   Interface ID was calculated.

   Some applications that use IPv6 packets on 802.11-OCB links (among
   other link types) may benefit from IPv6 addresses whose Interface
   Identifiers don't change too often.  It is RECOMMENDED to use the
   mechanisms described in RFC 7217 to permit the use of Stable
   Interface Identifiers that do not change within one subnet prefix.  A
   possible source for the Net-Iface Parameter is a virtual interface
   name, or logical interface name, that is decided by a local
   administrator.

   The way Interface Identifiers are used MAY involve risks to privacy,
   as described in Section 5.1.

4.7.  Subnet Structure

   A subnet is formed by the external 802.11-OCB interfaces of vehicles
   that are in close range (not by their in-vehicle interfaces).  This
   subnet MUST use at least the link-local prefix fe80::/10 and the
   interfaces MUST be assigned IPv6 addresses of type link-local.

   The structure of this subnet is ephemeral, in that it is strongly
   influenced by the mobility of vehicles: the 802.11 hidden node
   effects appear; the 802.11 networks in OCB mode may be considered as
   'ad-hoc' networks with an addressing model as described in [RFC5889].
   On another hand, the structure of the internal subnets in each car is
   relatively stable.

   As recommended in [RFC5889], when the timing requirements are very
   strict (e.g. fast drive through IP-RSU coverage), no on-link subnet
   prefix should be configured on an 802.11-OCB interface.  In such
   cases, the exclusive use of IPv6 link-local addresses is RECOMMENDED.

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   Additionally, even if the timing requirements are not very strict
   (e.g. the moving subnet formed by two following vehicles is stable, a
   fixed IP-RSU is absent), the subnet is disconnected from the Internet
   (a default route is absent), and the addressing peers are equally
   qualified (impossible to determine that some vehicle owns and
   distributes addresses to others) the use of link-local addresses is
   RECOMMENDED.

   The Neighbor Discovery protocol (ND) [RFC4861] is used over
   802.11-OCB links.

   Protocols like Mobile IPv6 [RFC6275] and DNAv6 [RFC6059], which
   depend on timely movement detection, might need additional tuning
   work to handle the lack of link-layer notifications during handover.
   This is for further study.

5.  Security Considerations

   Any security mechanism at the IP layer or above that may be carried
   out for the general case of IPv6 may also be carried out for IPv6
   operating over 802.11-OCB.

   The OCB operation is stripped off of all existing 802.11 link-layer
   security mechanisms.  There is no encryption applied below the
   network layer running on 802.11-OCB.  At application layer, the IEEE
   1609.2 document [IEEE-1609.2] does provide security services for
   certain applications to use; application-layer mechanisms are out-of-
   scope of this document.  On another hand, a security mechanism
   provided at networking layer, such as IPsec [RFC4301], may provide
   data security protection to a wider range of applications.

   802.11-OCB does not provide any cryptographic protection, because it
   operates outside the context of a BSS (no Association Request/
   Response, no Challenge messages).  Any attacker can therefore just
   sit in the near range of vehicles, sniff the network (just set the
   interface card's frequency to the proper range) and perform attacks
   without needing to physically break any wall.  Such a link is less
   protected than commonly used links (wired link or protected 802.11).

   The potential attack vectors are: MAC address spoofing, IP address
   and session hijacking, and privacy violation Section 5.1.

   Within the IPsec Security Architecture [RFC4301], the IPsec AH and
   ESP headers [RFC4302] and [RFC4303] respectively, its multicast
   extensions [RFC5374], HTTPS [RFC2818] and SeND [RFC3971] protocols
   can be used to protect communications.  Further, the assistance of
   proper Public Key Infrastructure (PKI) protocols [RFC4210] is
   necessary to establish credentials.  More IETF protocols are

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   available in the toolbox of the IP security protocol designer.
   Certain ETSI protocols related to security protocols in Intelligent
   Transportation Systems are described in [ETSI-sec-archi].

5.1.  Privacy Considerations

   As with all Ethernet and 802.11 interface identifiers ([RFC7721]),
   the identifier of an 802.11-OCB interface may involve privacy, MAC
   address spoofing and IP address hijacking risks.  A vehicle embarking
   an IP-OBU whose egress interface is 802.11-OCB may expose itself to
   eavesdropping and subsequent correlation of data; this may reveal
   data considered private by the vehicle owner; there is a risk of
   being tracked.  In outdoors public environments, where vehicles
   typically circulate, the privacy risks are more important than in
   indoors settings.  It is highly likely that attacker sniffers are
   deployed along routes which listen for IEEE frames, including IP
   packets, of vehicles passing by.  For this reason, in the 802.11-OCB
   deployments, there is a strong necessity to use protection tools such
   as dynamically changing MAC addresses Section 5.2, semantically
   opaque Interface Identifiers and stable Interface Identifiers
   Section 4.6.  This may help mitigate privacy risks to a certain
   level.

5.2.  MAC Address and Interface ID Generation

   In 802.11-OCB networks, the MAC addresses MAY change during well
   defined renumbering events.  In the moment the MAC address is changed
   on an 802.11-OCB interface all the Interface Identifiers of IPv6
   addresses assigned to that interface MUST change.

   The policy dictating when the MAC address is changed on the
   802.11-OCB interface is to-be-determined.  For more information on
   the motivation of this policy please refer to the privacy discussion
   in Appendix C.

   A 'randomized' MAC address has the following characteristics:

   o  Bit "Local/Global" set to "locally admninistered".

   o  Bit "Unicast/Multicast" set to "Unicast".

   o  The 46 remaining bits are set to a random value, using a random
      number generator that meets the requirements of [RFC4086].

   To meet the randomization requirements for the 46 remaining bits, a
   hash function may be used.  For example, the SHA256 hash function may
   be used with input a 256 bit local secret, the 'nominal' MAC Address

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   of the interface, and a representation of the date and time of the
   renumbering event.

   A randomized Interface ID has the same characteristics of a
   randomized MAC address, except the length in bits.  A MAC address
   SHOULD be of length 48 decimal.  An Interface ID SHOULD be of length
   64 decimal for all types of IPv6 addresses.  In the particular case
   of IPv6 link-local addresses, the length of the Interface ID MAY be
   118 decimal.

6.  IANA Considerations

   No request to IANA.

7.  Contributors

   Christian Huitema, Tony Li.

   Romain Kuntz contributed extensively about IPv6 handovers between
   links running outside the context of a BSS (802.11-OCB links).

   Tim Leinmueller contributed the idea of the use of IPv6 over
   802.11-OCB for distribution of certificates.

   Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey
   Voronov provided significant feedback on the experience of using IP
   messages over 802.11-OCB in initial trials.

   Michelle Wetterwald contributed extensively the MTU discussion,
   offered the ETSI ITS perspective, and reviewed other parts of the
   document.

8.  Acknowledgements

   The authors would like to thank Witold Klaudel, Ryuji Wakikawa,
   Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan
   Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray
   Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan,
   Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne,
   Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, Erik Nordmark,
   Bob Moskowitz, Andrew Dryden, Georg Mayer, Dorothy Stanley, Sandra
   Cespedes, Mariano Falcitelli, Sri Gundavelli, Abdussalam Baryun,
   Margaret Cullen, Erik Kline, Carlos Jesus Bernardos Cano, Ronald in
   't Velt, Katrin Sjoberg, Roland Bless, Tijink Jasja, Kevin Smith,
   Brian Carpenter, Julian Reschke, Mikael Abrahamsson, Dirk von Hugo,
   Lorenzo Colitti and William Whyte.  Their valuable comments clarified
   particular issues and generally helped to improve the document.

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   Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB
   drivers for linux and described how.

   For the multicast discussion, the authors would like to thank Owen
   DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and
   participants to discussions in network working groups.

   The authors would like to thank participants to the Birds-of-
   a-Feather "Intelligent Transportation Systems" meetings held at IETF
   in 2016.

   Human Rights Protocol Considerations review by Amelia Andersdotter.

9.  References

9.1.  Normative References

   [RFC1042]  Postel, J. and J. Reynolds, "Standard for the transmission
              of IP datagrams over IEEE 802 networks", STD 43, RFC 1042,
              DOI 10.17487/RFC1042, February 1988,
              <https://www.rfc-editor.org/info/rfc1042>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
              <https://www.rfc-editor.org/info/rfc2464>.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000,
              <https://www.rfc-editor.org/info/rfc2818>.

   [RFC3753]  Manner, J., Ed. and M. Kojo, Ed., "Mobility Related
              Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004,
              <https://www.rfc-editor.org/info/rfc3753>.

   [RFC3971]  Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
              "SEcure Neighbor Discovery (SEND)", RFC 3971,
              DOI 10.17487/RFC3971, March 2005,
              <https://www.rfc-editor.org/info/rfc3971>.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", BCP 106, RFC 4086,
              DOI 10.17487/RFC4086, June 2005,
              <https://www.rfc-editor.org/info/rfc4086>.

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   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
              <https://www.rfc-editor.org/info/rfc4193>.

   [RFC4210]  Adams, C., Farrell, S., Kause, T., and T. Mononen,
              "Internet X.509 Public Key Infrastructure Certificate
              Management Protocol (CMP)", RFC 4210,
              DOI 10.17487/RFC4210, September 2005,
              <https://www.rfc-editor.org/info/rfc4210>.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, DOI 10.17487/RFC4291, February
              2006, <https://www.rfc-editor.org/info/rfc4291>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302,
              DOI 10.17487/RFC4302, December 2005,
              <https://www.rfc-editor.org/info/rfc4302>.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/info/rfc4303>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC5374]  Weis, B., Gross, G., and D. Ignjatic, "Multicast
              Extensions to the Security Architecture for the Internet
              Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008,
              <https://www.rfc-editor.org/info/rfc5374>.

   [RFC5415]  Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
              Ed., "Control And Provisioning of Wireless Access Points
              (CAPWAP) Protocol Specification", RFC 5415,
              DOI 10.17487/RFC5415, March 2009,
              <https://www.rfc-editor.org/info/rfc5415>.

   [RFC5889]  Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing
              Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889,
              September 2010, <https://www.rfc-editor.org/info/rfc5889>.

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   [RFC6059]  Krishnan, S. and G. Daley, "Simple Procedures for
              Detecting Network Attachment in IPv6", RFC 6059,
              DOI 10.17487/RFC6059, November 2010,
              <https://www.rfc-editor.org/info/rfc6059>.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
              2011, <https://www.rfc-editor.org/info/rfc6275>.

   [RFC7042]  Eastlake 3rd, D. and J. Abley, "IANA Considerations and
              IETF Protocol and Documentation Usage for IEEE 802
              Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042,
              October 2013, <https://www.rfc-editor.org/info/rfc7042>.

   [RFC7136]  Carpenter, B. and S. Jiang, "Significance of IPv6
              Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136,
              February 2014, <https://www.rfc-editor.org/info/rfc7136>.

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217,
              DOI 10.17487/RFC7217, April 2014,
              <https://www.rfc-editor.org/info/rfc7217>.

   [RFC7721]  Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
              Considerations for IPv6 Address Generation Mechanisms",
              RFC 7721, DOI 10.17487/RFC7721, March 2016,
              <https://www.rfc-editor.org/info/rfc7721>.

   [RFC8064]  Gont, F., Cooper, A., Thaler, D., and W. Liu,
              "Recommendation on Stable IPv6 Interface Identifiers",
              RFC 8064, DOI 10.17487/RFC8064, February 2017,
              <https://www.rfc-editor.org/info/rfc8064>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

9.2.  Informative References

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   [ETSI-sec-archi]
              "ETSI TS 102 940 V1.2.1 (2016-11), ETSI Technical
              Specification, Intelligent Transport Systems (ITS);
              Security; ITS communications security architecture and
              security management, November 2016.  Downloaded on
              September 9th, 2017, freely available from ETSI website at
              URL http://www.etsi.org/deliver/
              etsi_ts/102900_102999/102940/01.02.01_60/
              ts_102940v010201p.pdf".

   [I-D.hinden-6man-rfc2464bis]
              Crawford, M. and R. Hinden, "Transmission of IPv6 Packets
              over Ethernet Networks", draft-hinden-6man-rfc2464bis-02
              (work in progress), March 2017.

   [I-D.ietf-ipwave-vehicular-networking-survey]
              Jeong, J., Cespedes, S., Benamar, N., Haerri, J., and M.
              Wetterwald, "Survey on IP-based Vehicular Networking for
              Intelligent Transportation Systems", draft-ietf-ipwave-
              vehicular-networking-survey-00 (work in progress), July
              2017.

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

   [IEEE-1609.2]
              "IEEE SA - 1609.2-2016 - IEEE Standard for Wireless Access
              in Vehicular Environments (WAVE) -- Security Services for
              Applications and Management Messages.  Example URL
              http://ieeexplore.ieee.org/document/7426684/ accessed on
              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.".

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   [IEEE-802.11-2016]
              "IEEE Standard 802.11-2016 - 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. Status - Active Standard.  Description
              retrieved freely on September 12th, 2017, at URL
              https://standards.ieee.org/findstds/
              standard/802.11-2016.html".

   [IEEE-802.11p-2010]
              "IEEE Std 802.11p (TM)-2010, 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,
              Amendment 6: Wireless Access in Vehicular Environments;
              document freely available at URL
              http://standards.ieee.org/getieee802/
              download/802.11p-2010.pdf retrieved on September 20th,
              2013.".

Appendix A.  ChangeLog

   The changes are listed in reverse chronological order, most recent
   changes appearing at the top of the list.

   -32: significantly shortened the relevant ND/OCB paragraph.  It now
   just states ND is used over OCB, w/o detailing.

   -31: filled in the section titled "Pseudonym Handling"; removed a
   'MAY NOT' phrase about possibility of having other prefix than the LL
   on the link between cars; shortened and improved the paragraph about
   Mobile IPv6, now with DNAv6; improved the ND text about ND
   retransmissions with relationship to packet loss; changed the title
   of an appendix from 'EPD' to 'Protocol Layering'; improved the
   'Aspects introduced by OCB' appendix with a few phrases about the
   channel use and references.

   -30: a clarification on the reliability of ND over OCB and over
   802.11.

   -29:

   o

   -28:

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   o  Created a new section 'Pseudonym Handling'.

   o  removed the 'Vehicle ID' appendix.

   o  improved the address generation from random MAC address.

   o  shortened Term IP-RSU definition.

   o  removed refs to two detail Clauses in IEEE documents, kept just
      these latter.

   -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
   appendix about privacy into a new Privacy Condiderations subsection
   of the Security section; reformulated the SLAAC and IID sections to
   stress only LLs can use EUI-64; removed the "GeoIP" wireshark
   explanation; reformulated SLAAC and LL sections; added brief mention
   of need of use LLs; clarified text about MAC address changes; dropped
   pseudonym discussion; changed title of section describing examples of
   packet formats.

   -25: added a reference to 'IEEE Management Information Base', instead
   of just 'Management Information Base'; added ref to further
   appendices in the introductory phrases; improved text for IID
   formation for SLAAC, inserting recommendation for RFC8064 before
   RFC2464.

   From draft-ietf-ipwave-ipv6-over-80211ocb-23 to draft-ietf-ipwave-
   ipv6-over-80211ocb-24

   o  Nit: wrote "IPWAVE Working Group" on the front page, instead of
      "Network Working Group".

   o  Addressed the comments on 6MAN: replaced a sentence about ND
      problem with "is used over 802.11-OCB".

   From draft-ietf-ipwave-ipv6-over-80211ocb-22 to draft-ietf-ipwave-
   ipv6-over-80211ocb-23

   o  No content modifications, but check the entire draft chain on
      IPv6-only: xml2rfc, submission on tools.ietf.org and datatracker.

   From draft-ietf-ipwave-ipv6-over-80211ocb-21 to draft-ietf-ipwave-
   ipv6-over-80211ocb-22

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   o  Corrected typo, use dash in "802.11-OCB" instead of space.

   o  Improved the Frame Format section: MUST use QoSData, specify the
      values within; clarified the Ethernet Adaptation Layer text.

   From draft-ietf-ipwave-ipv6-over-80211ocb-20 to draft-ietf-ipwave-
   ipv6-over-80211ocb-21

   o  Corrected a few nits and added names in Acknowledgments section.

   o  Removed unused reference to old Internet Draft tsvwg about QoS.

   From draft-ietf-ipwave-ipv6-over-80211ocb-19 to draft-ietf-ipwave-
   ipv6-over-80211ocb-20

   o  Reduced the definition of term "802.11-OCB".

   o  Left out of this specification which 802.11 header to use to
      transmit IP packets in OCB mode (QoS Data header, Data header, or
      any other).

   o  Added 'MUST' use an Ethernet Adaptation Layer, instead of 'is
      using' an Ethernet Adaptation Layer.

   From draft-ietf-ipwave-ipv6-over-80211ocb-18 to draft-ietf-ipwave-
   ipv6-over-80211ocb-19

   o  Removed the text about fragmentation.

   o  Removed the mentioning of WSMP and GeoNetworking.

   o  Removed the explanation of the binary representation of the
      EtherType.

   o  Rendered normative the paragraph about unicast and multicast
      address mapping.

   o  Removed paragraph about addressing model, subnet structure and
      easiness of using LLs.

   o  Clarified the Type/Subtype field in the 802.11 Header.

   o  Used RECOMMENDED instead of recommended, for the stable interface
      identifiers.

   From draft-ietf-ipwave-ipv6-over-80211ocb-17 to draft-ietf-ipwave-
   ipv6-over-80211ocb-18

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   o  Improved the MTU and fragmentation paragraph.

   From draft-ietf-ipwave-ipv6-over-80211ocb-16 to draft-ietf-ipwave-
   ipv6-over-80211ocb-17

   o  Susbtituted "MUST be increased" to "is increased" in the MTU
      section, about fragmentation.

   From draft-ietf-ipwave-ipv6-over-80211ocb-15 to draft-ietf-ipwave-
   ipv6-over-80211ocb-16

   o  Removed the definition of the 'WiFi' term and its occurences.
      Clarified a phrase that used it in Appendix C "Aspects introduced
      by the OCB mode to 802.11".

   o  Added more normative words: MUST be 0x86DD, MUST fragment if size
      larger than MTU, Sequence number in 802.11 Data header MUST be
      increased.

   From draft-ietf-ipwave-ipv6-over-80211ocb-14 to draft-ietf-ipwave-
   ipv6-over-80211ocb-15

   o  Added normative term MUST in two places in section "Ethernet
      Adaptation Layer".

   From draft-ietf-ipwave-ipv6-over-80211ocb-13 to draft-ietf-ipwave-
   ipv6-over-80211ocb-14

   o  Created a new Appendix titled "Extra Terminology" that contains
      terms DSRC, DSRCS, OBU, RSU as defined outside IETF.  Some of them
      are used in the main Terminology section.

   o  Added two paragraphs explaining that ND and Mobile IPv6 have
      problems working over 802.11-OCB, yet their adaptations is not
      specified in this document.

   From draft-ietf-ipwave-ipv6-over-80211ocb-12 to draft-ietf-ipwave-
   ipv6-over-80211ocb-13

   o  Substituted "IP-OBU" for "OBRU", and "IP-RSU" for "RSRU"
      throughout and improved OBU-related definitions in the Terminology
      section.

   From draft-ietf-ipwave-ipv6-over-80211ocb-11 to draft-ietf-ipwave-
   ipv6-over-80211ocb-12

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   o  Improved the appendix about "MAC Address Generation" by expressing
      the technique to be an optional suggestion, not a mandatory
      mechanism.

   From draft-ietf-ipwave-ipv6-over-80211ocb-10 to draft-ietf-ipwave-
   ipv6-over-80211ocb-11

   o  Shortened the paragraph on forming/terminating 802.11-OCB links.

   o  Moved the draft tsvwg-ieee-802-11 to Informative References.

   From draft-ietf-ipwave-ipv6-over-80211ocb-09 to draft-ietf-ipwave-
   ipv6-over-80211ocb-10

   o  Removed text requesting a new Group ID for multicast for OCB.

   o  Added a clarification of the meaning of value "3333" in the
      section Address Mapping -- Multicast.

   o  Added note clarifying that in Europe the regional authority is not
      ETSI, but "ECC/CEPT based on ENs from ETSI".

   o  Added note stating that the manner in which two STAtions set their
      communication channel is not described in this document.

   o  Added a time qualifier to state that the "each node is represented
      uniquely at a certain point in time."

   o  Removed text "This section may need to be moved" (the "Reliability
      Requirements" section).  This section stays there at this time.

   o  In the term definition "802.11-OCB" added a note stating that "any
      implementation should comply with standards and regulations set in
      the different countries for using that frequency band."

   o  In the RSU term definition, added a sentence explaining the
      difference between RSU and RSRU: in terms of number of interfaces
      and IP forwarding.

   o  Replaced "with at least two IP interfaces" with "with at least two
      real or virtual IP interfaces".

   o  Added a term in the Terminology for "OBU".  However the definition
      is left empty, as this term is defined outside IETF.

   o  Added a clarification that it is an OBU or an OBRU in this phrase
      "A vehicle embarking an OBU or an OBRU".

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   o  Checked the entire document for a consistent use of terms OBU and
      OBRU.

   o  Added note saying that "'p' is a letter identifying the
      Ammendment".

   o  Substituted lower case for capitals SHALL or MUST in the
      Appendices.

   o  Added reference to RFC7042, helpful in the 3333 explanation.
      Removed reference to individual submission draft-petrescu-its-
      scenario-reqs and added reference to draft-ietf-ipwave-vehicular-
      networking-survey.

   o  Added figure captions, figure numbers, and references to figure
      numbers instead of 'below'.  Replaced "section Section" with
      "section" throughout.

   o  Minor typographical errors.

   From draft-ietf-ipwave-ipv6-over-80211ocb-08 to draft-ietf-ipwave-
   ipv6-over-80211ocb-09

   o  Significantly shortened the Address Mapping sections, by text
      copied from RFC2464, and rather referring to it.

   o  Moved the EPD description to an Appendix on its own.

   o  Shortened the Introduction and the Abstract.

   o  Moved the tutorial section of OCB mode introduced to .11, into an
      appendix.

   o  Removed the statement that suggests that for routing purposes a
      prefix exchange mechanism could be needed.

   o  Removed refs to RFC3963, RFC4429 and RFC6775; these are about ND,
      MIP/NEMO and oDAD; they were referred in the handover discussion
      section, which is out.

   o  Updated a reference from individual submission to now a WG item in
      IPWAVE: the survey document.

   o  Added term definition for WiFi.

   o  Updated the authorship and expanded the Contributors section.

   o  Corrected typographical errors.

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   From draft-ietf-ipwave-ipv6-over-80211ocb-07 to draft-ietf-ipwave-
   ipv6-over-80211ocb-08

   o  Removed the per-channel IPv6 prohibition text.

   o  Corrected typographical errors.

   From draft-ietf-ipwave-ipv6-over-80211ocb-06 to draft-ietf-ipwave-
   ipv6-over-80211ocb-07

   o  Added new terms: OBRU and RSRU ('R' for Router).  Refined the
      existing terms RSU and OBU, which are no longer used throughout
      the document.

   o  Improved definition of term "802.11-OCB".

   o  Clarified that OCB does not "strip" security, but that the
      operation in OCB mode is "stripped off of all .11 security".

   o  Clarified that theoretical OCB bandwidth speed is 54mbits, but
      that a commonly observed bandwidth in IP-over-OCB is 12mbit/s.

   o  Corrected typographical errors, and improved some phrasing.

   From draft-ietf-ipwave-ipv6-over-80211ocb-05 to draft-ietf-ipwave-
   ipv6-over-80211ocb-06

   o  Updated references of 802.11-OCB document from -2012 to the IEEE
      802.11-2016.

   o  In the LL address section, and in SLAAC section, added references
      to 7217 opaque IIDs and 8064 stable IIDs.

   From draft-ietf-ipwave-ipv6-over-80211ocb-04 to draft-ietf-ipwave-
   ipv6-over-80211ocb-05

   o  Lengthened the title and cleanded the abstract.

   o  Added text suggesting LLs may be easy to use on OCB, rather than
      GUAs based on received prefix.

   o  Added the risks of spoofing and hijacking.

   o  Removed the text speculation on adoption of the TSA message.

   o  Clarified that the ND protocol is used.

   o  Clarified what it means "No association needed".

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   o  Added some text about how two STAs discover each other.

   o  Added mention of external (OCB) and internal network (stable), in
      the subnet structure section.

   o  Added phrase explaining that both .11 Data and .11 QoS Data
      headers are currently being used, and may be used in the future.

   o  Moved the packet capture example into an Appendix Implementation
      Status.

   o  Suggested moving the reliability requirements appendix out into
      another document.

   o  Added a IANA Consiserations section, with content, requesting for
      a new multicast group "all OCB interfaces".

   o  Added new OBU term, improved the RSU term definition, removed the
      ETTC term, replaced more occurences of 802.11p, 802.11-OCB with
      802.11-OCB.

   o  References:

      *  Added an informational reference to ETSI's IPv6-over-
         GeoNetworking.

      *  Added more references to IETF and ETSI security protocols.

      *  Updated some references from I-D to RFC, and from old RFC to
         new RFC numbers.

      *  Added reference to multicast extensions to IPsec architecture
         RFC.

      *  Added a reference to 2464-bis.

      *  Removed FCC informative references, because not used.

   o  Updated the affiliation of one author.

   o  Reformulation of some phrases for better readability, and
      correction of typographical errors.

   From draft-ietf-ipwave-ipv6-over-80211ocb-03 to draft-ietf-ipwave-
   ipv6-over-80211ocb-04

   o  Removed a few informative references pointing to Dx draft IEEE
      1609 documents.

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   o  Removed outdated informative references to ETSI documents.

   o  Added citations to IEEE 1609.2, .3 and .4-2016.

   o  Minor textual issues.

   From draft-ietf-ipwave-ipv6-over-80211ocb-02 to draft-ietf-ipwave-
   ipv6-over-80211ocb-03

   o  Keep the previous text on multiple addresses, so remove talk about
      MIP6, NEMOv6 and MCoA.

   o  Clarified that a 'Beacon' is an IEEE 802.11 frame Beacon.

   o  Clarified the figure showing Infrastructure mode and OCB mode side
      by side.

   o  Added a reference to the IP Security Architecture RFC.

   o  Detailed the IPv6-per-channel prohibition paragraph which reflects
      the discussion at the last IETF IPWAVE WG meeting.

   o  Added section "Address Mapping -- Unicast".

   o  Added the ".11 Trailer" to pictures of 802.11 frames.

   o  Added text about SNAP carrying the Ethertype.

   o  New RSU definition allowing for it be both a Router and not
      necessarily a Router some times.

   o  Minor textual issues.

   From draft-ietf-ipwave-ipv6-over-80211ocb-01 to draft-ietf-ipwave-
   ipv6-over-80211ocb-02

   o  Replaced almost all occurences of 802.11p with 802.11-OCB, leaving
      only when explanation of evolution was necessary.

   o  Shortened by removing parameter details from a paragraph in the
      Introduction.

   o  Moved a reference from Normative to Informative.

   o  Added text in intro clarifying there is no handover spec at IEEE,
      and that 1609.2 does provide security services.

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   o  Named the contents the fields of the EthernetII header (including
      the Ethertype bitstring).

   o  Improved relationship between two paragraphs describing the
      increase of the Sequence Number in 802.11 header upon IP
      fragmentation.

   o  Added brief clarification of "tracking".

   From draft-ietf-ipwave-ipv6-over-80211ocb-00 to draft-ietf-ipwave-
   ipv6-over-80211ocb-01

   o  Introduced message exchange diagram illustrating differences
      between 802.11 and 802.11 in OCB mode.

   o  Introduced an appendix listing for information the set of 802.11
      messages that may be transmitted in OCB mode.

   o  Removed appendix sections "Privacy Requirements", "Authentication
      Requirements" and "Security Certificate Generation".

   o  Removed appendix section "Non IP Communications".

   o  Introductory phrase in the Security Considerations section.

   o  Improved the definition of "OCB".

   o  Introduced theoretical stacked layers about IPv6 and IEEE layers
      including EPD.

   o  Removed the appendix describing the details of prohibiting IPv6 on
      certain channels relevant to 802.11-OCB.

   o  Added a brief reference in the privacy text about a precise clause
      in IEEE 1609.3 and .4.

   o  Clarified the definition of a Road Side Unit.

   o  Removed the discussion about security of WSA (because is non-IP).

   o  Removed mentioning of the GeoNetworking discussion.

   o  Moved references to scientific articles to a separate 'overview'
      draft, and referred to it.

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Appendix B.  802.11p

   The term "802.11p" is an earlier definition.  The behaviour of
   "802.11p" networks is rolled in the document IEEE Std 802.11-2016.
   In that document the term 802.11p disappears.  Instead, each 802.11p
   feature is conditioned by the IEEE Management Information Base (MIB)
   attribute "OCBActivated" [IEEE-802.11-2016].  Whenever OCBActivated
   is set to true the IEEE Std 802.11-OCB state is activated.  For
   example, an 802.11 STAtion operating outside the context of a basic
   service set has the OCBActivated flag set.  Such a station, when it
   has the flag set, uses a BSS identifier equal to ff:ff:ff:ff:ff:ff.

Appendix C.  Aspects introduced by the OCB mode to 802.11

   In the IEEE 802.11-OCB mode, all nodes in the wireless range can
   directly communicate with each other without involving authentication
   or association procedures.  In OCB mode, the manner in which channels
   are selected and used is simplified compared to when in BSS mode.
   Contrary to BSS mode, at link layer, it is necessary to set
   statically the same channel number (or frequency) on two stations
   that need to communicate with each other (in BSS mode this channel
   set operation is performed automatically during 'scanning').  The
   manner in which stations set their channel number in OCB mode is not
   specified in this document.  Stations STA1 and STA2 can exchange IP
   packets only if they are set on the same channel.  At IP layer, they
   then discover each other by using the IPv6 Neighbor Discovery
   protocol.  The allocation of a particular channel for a particular
   use is defined statically in standards authored by ETSI (in Europe),
   FCC in America, and similar organisations in South Korea, Japan and
   other parts of the world.

   Briefly, the IEEE 802.11-OCB mode has the following properties:

   o  The use by each node of a 'wildcard' BSSID (i.e., each bit of the
      BSSID is set to 1)

   o  No IEEE 802.11 Beacon frames are transmitted

   o  No authentication is required in order to be able to communicate

   o  No association is needed in order to be able to communicate

   o  No encryption is provided in order to be able to communicate

   o  Flag dot11OCBActivated is set to true

   All the nodes in the radio communication range (IP-OBU and IP-RSU)
   receive all the messages transmitted (IP-OBU and IP-RSU) within the

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   radio communications range.  The eventual conflict(s) are resolved by
   the MAC CDMA function.

   The message exchange diagram in Figure 3 illustrates a comparison
   between traditional 802.11 and 802.11 in OCB mode.  The 'Data'
   messages can be IP packets such as HTTP or others.  Other 802.11
   management and control frames (non IP) may be transmitted, as
   specified in the 802.11 standard.  For information, the names of
   these messages as currently specified by the 802.11 standard are
   listed in Appendix G.

      STA                    AP              STA1                   STA2
      |                      |               |                      |
      |<------ Beacon -------|               |<------ Data -------->|
      |                      |               |                      |
      |---- Probe Req. ----->|               |<------ Data -------->|
      |<--- Probe Res. ------|               |                      |
      |                      |               |<------ Data -------->|
      |---- Auth Req. ------>|               |                      |
      |<--- Auth Res. -------|               |<------ Data -------->|
      |                      |               |                      |
      |---- Asso Req. ------>|               |<------ Data -------->|
      |<--- Asso Res. -------|               |                      |
      |                      |               |<------ Data -------->|
      |<------ Data -------->|               |                      |
      |<------ Data -------->|               |<------ Data -------->|

         (i) 802.11 Infrastructure mode         (ii) 802.11-OCB mode

   Figure 3: Difference between messages exchanged on 802.11 (left) and
                            802.11-OCB (right)

   The interface 802.11-OCB was specified in IEEE Std 802.11p (TM) -2010
   [IEEE-802.11p-2010] as an amendment to IEEE Std 802.11 (TM) -2007,
   titled "Amendment 6: Wireless Access in Vehicular Environments".
   Since then, this amendment has been integrated in IEEE 802.11(TM)
   -2012 and -2016 [IEEE-802.11-2016].

   In document 802.11-2016, anything qualified specifically as
   "OCBActivated", or "outside the context of a basic service" set to be
   true, then it is actually referring to OCB aspects introduced to
   802.11.

   In order to delineate the aspects introduced by 802.11-OCB to 802.11,
   we refer to the earlier [IEEE-802.11p-2010].  The amendment is
   concerned with vehicular communications, where the wireless link is

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   similar to that of Wireless LAN (using a PHY layer specified by
   802.11a/b/g/n), but which needs to cope with the high mobility factor
   inherent in scenarios of communications between moving vehicles, and
   between vehicles and fixed infrastructure deployed along roads.
   While 'p' is a letter identifying the Ammendment, just like 'a, b, g'
   and 'n' are, 'p' is concerned more with MAC modifications, and a
   little with PHY modifications; the others are mainly about PHY
   modifications.  It is possible in practice to combine a 'p' MAC with
   an 'a' PHY by operating outside the context of a BSS with OFDM at
   5.4GHz and 5.9GHz.

   The 802.11-OCB links are specified to be compatible as much as
   possible with the behaviour of 802.11a/b/g/n and future generation
   IEEE WLAN links.  From the IP perspective, an 802.11-OCB MAC layer
   offers practically the same interface to IP as the 802.11a/b/g/n and
   802.3.  A packet sent by an IP-OBU may be received by one or multiple
   IP-RSUs.  The link-layer resolution is performed by using the IPv6
   Neighbor Discovery protocol.

   To support this similarity statement (IPv6 is layered on top of LLC
   on top of 802.11-OCB, in the same way that IPv6 is layered on top of
   LLC on top of 802.11a/b/g/n (for WLAN) or layered on top of LLC on
   top of 802.3 (for Ethernet)) it is useful to analyze the differences
   between 802.11-OCB and 802.11 specifications.  During this analysis,
   we note that whereas 802.11-OCB lists relatively complex and numerous
   changes to the MAC layer (and very little to the PHY layer), there
   are only a few characteristics which may be important for an
   implementation transmitting IPv6 packets on 802.11-OCB links.

   The most important 802.11-OCB point which influences the IPv6
   functioning is the OCB characteristic; an additional, less direct
   influence, is the maximum bandwidth afforded by the PHY modulation/
   demodulation methods and channel access specified by 802.11-OCB.  The
   maximum bandwidth theoretically possible in 802.11-OCB is 54 Mbit/s
   (when using, for example, the following parameters: 20 MHz channel;
   modulation 64-QAM; coding rate R is 3/4); in practice of IP-over-
   802.11-OCB a commonly observed figure is 12Mbit/s; this bandwidth
   allows the operation of a wide range of protocols relying on IPv6.

   o  Operation Outside the Context of a BSS (OCB): the (earlier
      802.11p) 802.11-OCB links are operated without a Basic Service Set
      (BSS).  This means that the frames IEEE 802.11 Beacon, Association
      Request/Response, Authentication Request/Response, and similar,
      are not used.  The used identifier of BSS (BSSID) has a
      hexadecimal value always 0xffffffffffff (48 '1' bits, represented
      as MAC address ff:ff:ff:ff:ff:ff, or otherwise the 'wildcard'
      BSSID), as opposed to an arbitrary BSSID value set by
      administrator (e.g.  'My-Home-AccessPoint').  The OCB operation -

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      namely the lack of beacon-based scanning and lack of
      authentication - should be taken into account when the Mobile IPv6
      protocol [RFC6275] and the protocols for IP layer security
      [RFC4301] are used.  The way these protocols adapt to OCB is not
      described in this document.

   o  Timing Advertisement: is a new message defined in 802.11-OCB,
      which does not exist in 802.11a/b/g/n.  This message is used by
      stations to inform other stations about the value of time.  It is
      similar to the time as delivered by a GNSS system (Galileo, GPS,
      ...) or by a cellular system.  This message is optional for
      implementation.

   o  Frequency range: this is a characteristic of the PHY layer, with
      almost no impact on the interface between MAC and IP.  However, it
      is worth considering that the frequency range is regulated by a
      regional authority (ARCEP, ECC/CEPT based on ENs from ETSI, FCC,
      etc.); as part of the regulation process, specific applications
      are associated with specific frequency ranges.  In the case of
      802.11-OCB, the regulator associates a set of frequency ranges, or
      slots within a band, to the use of applications of vehicular
      communications, in a band known as "5.9GHz".  The 5.9GHz band is
      different from the 2.4GHz and 5GHz bands used by Wireless LAN.
      However, as with Wireless LAN, the operation of 802.11-OCB in
      "5.9GHz" bands is exempt from owning a license in EU (in US the
      5.9GHz is a licensed band of spectrum; for the fixed
      infrastructure an explicit FCC authorization is required; for an
      on-board device a 'licensed-by-rule' concept applies: rule
      certification conformity is required.)  Technical conditions are
      different than those of the bands "2.4GHz" or "5GHz".  The allowed
      power levels, and implicitly the maximum allowed distance between
      vehicles, is of 33dBm for 802.11-OCB (in Europe), compared to 20
      dBm for Wireless LAN 802.11a/b/g/n; this leads to a maximum
      distance of approximately 1km, compared to approximately 50m.
      Additionally, specific conditions related to congestion avoidance,
      jamming avoidance, and radar detection are imposed on the use of
      DSRC (in US) and on the use of frequencies for Intelligent
      Transportation Systems (in EU), compared to Wireless LAN
      (802.11a/b/g/n).

   o  'Half-rate' encoding: as the frequency range, this parameter is
      related to PHY, and thus has not much impact on the interface
      between the IP layer and the MAC layer.

   o  In vehicular communications using 802.11-OCB links, there are
      strong privacy requirements with respect to addressing.  While the
      802.11-OCB standard does not specify anything in particular with
      respect to MAC addresses, in these settings there exists a strong

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      need for dynamic change of these addresses (as opposed to the non-
      vehicular settings - real wall protection - where fixed MAC
      addresses do not currently pose some privacy risks).  This is
      further described in Section 5.  A relevant function is described
      in documents IEEE 1609.3-2016 [IEEE-1609.3] and IEEE 1609.4-2016
      [IEEE-1609.4].

Appendix D.  Changes Needed on a software driver 802.11a to become a
             802.11-OCB driver

   The 802.11p amendment modifies both the 802.11 stack's physical and
   MAC layers but all the induced modifications can be quite easily
   obtained by modifying an existing 802.11a ad-hoc stack.

   Conditions for a 802.11a hardware to be 802.11-OCB compliant:

   o  The PHY entity shall be an orthogonal frequency division
      multiplexing (OFDM) system.  It must support the frequency bands
      on which the regulator recommends the use of ITS communications,
      for example using IEEE 802.11-OCB layer, in France: 5875MHz to
      5925MHz.

   o  The OFDM system must provide a "half-clocked" operation using 10
      MHz channel spacings.

   o  The chip transmit spectrum mask must be compliant to the "Transmit
      spectrum mask" from the IEEE 802.11p amendment (but experimental
      environments tolerate otherwise).

   o  The chip should be able to transmit up to 44.8 dBm when used by
      the US government in the United States, and up to 33 dBm in
      Europe; other regional conditions apply.

   Changes needed on the network stack in OCB mode:

   o  Physical layer:

      *  The chip must use the Orthogonal Frequency Multiple Access
         (OFDM) encoding mode.

      *  The chip must be set in half-mode rate mode (the internal clock
         frequency is divided by two).

      *  The chip must use dedicated channels and should allow the use
         of higher emission powers.  This may require modifications to
         the local computer file that describes regulatory domains
         rules, if used by the kernel to enforce local specific

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         restrictions.  Such modifications to the local computer file
         must respect the location-specific regulatory rules.

      MAC layer:

      *  All management frames (beacons, join, leave, and others)
         emission and reception must be disabled except for frames of
         subtype Action and Timing Advertisement (defined below).

      *  No encryption key or method must be used.

      *  Packet emission and reception must be performed as in ad-hoc
         mode, using the wildcard BSSID (ff:ff:ff:ff:ff:ff).

      *  The functions related to joining a BSS (Association Request/
         Response) and for authentication (Authentication Request/Reply,
         Challenge) are not called.

      *  The beacon interval is always set to 0 (zero).

      *  Timing Advertisement frames, defined in the amendment, should
         be supported.  The upper layer should be able to trigger such
         frames emission and to retrieve information contained in
         received Timing Advertisements.

Appendix E.  Protocol Layering

   A more theoretical and detailed view of layer stacking, and
   interfaces between the IP layer and 802.11-OCB layers, is illustrated
   in Figure 4.  The IP layer operates on top of the EtherType Protocol
   Discrimination (EPD); this Discrimination layer is described in IEEE
   Std 802.3-2012; the interface between IPv6 and EPD is the LLC_SAP
   (Link Layer Control Service Access Point).

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           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |                 IPv6                  |
           +-+-+-+-+-+-{            }+-+-+-+-+-+-+-+
                       {   LLC_SAP  }                 802.11-OCB
           +-+-+-+-+-+-{            }+-+-+-+-+-+-+-+  Boundary
           |            EPD          |       |     |
           |                         | MLME  |     |
           +-+-+-{  MAC_SAP   }+-+-+-|  MLME_SAP   |
           |      MAC Sublayer       |       |     |  802.11-OCB
           |     and ch. coord.      |       | SME |  Services
           +-+-+-{   PHY_SAP  }+-+-+-+-+-+-+-|     |
           |                         | PLME  |     |
           |            PHY Layer    |   PLME_SAP  |
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 4: EtherType Protocol Discrimination

Appendix F.  Design Considerations

   The networks defined by 802.11-OCB are in many ways similar to other
   networks of the 802.11 family.  In theory, the encapsulation of IPv6
   over 802.11-OCB could be very similar to the operation of IPv6 over
   other networks of the 802.11 family.  However, the high mobility,
   strong link asymmetry and very short connection makes the 802.11-OCB
   link significantly different from other 802.11 networks.  Also, the
   automotive applications have specific requirements for reliability,
   security and privacy, which further add to the particularity of the
   802.11-OCB link.

Appendix G.  IEEE 802.11 Messages Transmitted in OCB mode

   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
   dot11OCBActivated is true in a STA:

   o  The STA may send management frames of subtype Action and, if the
      STA maintains a TSF Timer, subtype Timing Advertisement;

   o  The STA may send control frames, except those of subtype PS-Poll,
      CF-End, and CF-End plus CFAck;

   o  The STA may send data frames of subtype Data, Null, QoS Data, and
      QoS Null.

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Appendix H.  Examples of Packet Formats

   This section describes an example of an IPv6 Packet captured over a
   IEEE 802.11-OCB link.

   By way of example we show that there is no modification in the
   headers when transmitted over 802.11-OCB networks - they are
   transmitted like any other 802.11 and Ethernet packets.

   We describe an experiment of capturing an IPv6 packet on an
   802.11-OCB link.  In topology depicted in Figure 5, the packet is an
   IPv6 Router Advertisement.  This packet is emitted by a Router on its
   802.11-OCB interface.  The packet is captured on the Host, using a
   network protocol analyzer (e.g.  Wireshark); the capture is performed
   in two different modes: direct mode and 'monitor' mode.  The topology
   used during the capture is depicted below.

   The packet is captured on the Host.  The Host is an IP-OBU containing
   an 802.11 interface in format PCI express (an ITRI product).  The
   kernel runs the ath5k software driver with modifications for OCB
   mode.  The capture tool is Wireshark.  The file format for save and
   analyze is 'pcap'.  The packet is generated by the Router.  The
   Router is an IP-RSU (ITRI product).

              +--------+                                +-------+
              |        |        802.11-OCB Link         |       |
           ---| Router |--------------------------------| Host  |
              |        |                                |       |
              +--------+                                +-------+

         Figure 5: Topology for capturing IP packets on 802.11-OCB

   During several capture operations running from a few moments to
   several hours, no message relevant to the BSSID contexts were
   captured (no Association Request/Response, Authentication Req/Resp,
   Beacon).  This shows that the operation of 802.11-OCB is outside the
   context of a BSSID.

   Overall, the captured message is identical with a capture of an IPv6
   packet emitted on a 802.11b interface.  The contents are precisely
   similar.

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H.1.  Capture in Monitor Mode

   The IPv6 RA packet captured in monitor mode is illustrated below.
   The radio tap header provides more flexibility for reporting the
   characteristics of frames.  The Radiotap Header is prepended by this
   particular stack and operating system on the Host machine to the RA
   packet received from the network (the Radiotap Header is not present
   on the air).  The implementation-dependent Radiotap Header is useful
   for piggybacking PHY information from the chip's registers as data in
   a packet understandable by userland applications using Socket
   interfaces (the PHY interface can be, for example: power levels, data
   rate, ratio of signal to noise).

   The packet present on the air is formed by IEEE 802.11 Data Header,
   Logical Link Control Header, IPv6 Base Header and ICMPv6 Header.

     Radiotap Header v0
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Header Revision|  Header Pad   |    Header length              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Present flags                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Data Rate     |             Pad                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     IEEE 802.11 Data Header
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Type/Subtype and Frame Ctrl  |          Duration             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Receiver Address...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ... Receiver Address           |      Transmitter Address...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Transmitter Address                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                            BSS Id...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... BSS Id                     |  Frag Number and Seq Number   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Logical-Link Control Header
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      DSAP   |I|     SSAP    |C| Control field | Org. code...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Organizational Code        |             Type              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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     IPv6 Base Header
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Version| Traffic Class |           Flow Label                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Payload Length        |  Next Header  |   Hop Limit   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                                                               |
     +                         Source Address                        +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                                                               |
     +                      Destination Address                      +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Router Advertisement
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type      |     Code      |          Checksum             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Cur Hop Limit |M|O|  Reserved |       Router Lifetime         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Reachable Time                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Retrans Timer                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Options ...
     +-+-+-+-+-+-+-+-+-+-+-+-

   The value of the Data Rate field in the Radiotap header is set to 6
   Mb/s.  This indicates the rate at which this RA was received.

   The value of the Transmitter address in the IEEE 802.11 Data Header
   is set to a 48bit value.  The value of the destination address is
   33:33:00:00:00:1 (all-nodes multicast address).  The value of the BSS
   Id field is ff:ff:ff:ff:ff:ff, which is recognized by the network
   protocol analyzer as being "broadcast".  The Fragment number and
   sequence number fields are together set to 0x90C6.

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   The value of the Organization Code field in the Logical-Link Control
   Header is set to 0x0, recognized as "Encapsulated Ethernet".  The
   value of the Type field is 0x86DD (hexadecimal 86DD, or otherwise
   #86DD), recognized as "IPv6".

   A Router Advertisement is periodically sent by the router to
   multicast group address ff02::1.  It is an icmp packet type 134.  The
   IPv6 Neighbor Discovery's Router Advertisement message contains an
   8-bit field reserved for single-bit flags, as described in [RFC4861].

   The IPv6 header contains the link local address of the router
   (source) configured via EUI-64 algorithm, and destination address set
   to ff02::1.

   The Ethernet Type field in the logical-link control header is set to
   0x86dd which indicates that the frame transports an IPv6 packet.  In
   the IEEE 802.11 data, the destination address is 33:33:00:00:00:01
   which is the corresponding multicast MAC address.  The BSS id is a
   broadcast address of ff:ff:ff:ff:ff:ff.  Due to the short link
   duration between vehicles and the roadside infrastructure, there is
   no need in IEEE 802.11-OCB to wait for the completion of association
   and authentication procedures before exchanging data.  IEEE
   802.11-OCB enabled nodes use the wildcard BSSID (a value of all 1s)
   and may start communicating as soon as they arrive on the
   communication channel.

H.2.  Capture in Normal Mode

   The same IPv6 Router Advertisement packet described above (monitor
   mode) is captured on the Host, in the Normal mode, and depicted
   below.

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     Ethernet II Header
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                       Destination...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...Destination                 |           Source...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...Source                                                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Type                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     IPv6 Base Header
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Version| Traffic Class |           Flow Label                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Payload Length        |  Next Header  |   Hop Limit   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                                                               |
     +                         Source Address                        +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                                                               |
     +                      Destination Address                      +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Router Advertisement
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type      |     Code      |          Checksum             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Cur Hop Limit |M|O|  Reserved |       Router Lifetime         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Reachable Time                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Retrans Timer                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Options ...
     +-+-+-+-+-+-+-+-+-+-+-+-

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   One notices that the Radiotap Header, the IEEE 802.11 Data Header and
   the Logical-Link Control Headers are not present.  On the other hand,
   a new header named Ethernet II Header is present.

   The Destination and Source addresses in the Ethernet II header
   contain the same values as the fields Receiver Address and
   Transmitter Address present in the IEEE 802.11 Data Header in the
   "monitor" mode capture.

   The value of the Type field in the Ethernet II header is 0x86DD
   (recognized as "IPv6"); this value is the same value as the value of
   the field Type in the Logical-Link Control Header in the "monitor"
   mode capture.

   The knowledgeable experimenter will no doubt notice the similarity of
   this Ethernet II Header with a capture in normal mode on a pure
   Ethernet cable interface.

   An Adaptation layer is inserted on top of a pure IEEE 802.11 MAC
   layer, in order to adapt packets, before delivering the payload data
   to the applications.  It adapts 802.11 LLC/MAC headers to Ethernet II
   headers.  In further detail, this adaptation consists in the
   elimination of the Radiotap, 802.11 and LLC headers, and in the
   insertion of the Ethernet II header.  In this way, IPv6 runs straight
   over LLC over the 802.11-OCB MAC layer; this is further confirmed by
   the use of the unique Type 0x86DD.

Appendix I.  Extra Terminology

   The following terms are defined outside the IETF.  They are used to
   define the main terms in the main terminology section Section 2.

   DSRC (Dedicated Short Range Communication): a term defined outside
   the IETF.  The US Federal Communications Commission (FCC) Dedicated
   Short Range Communication (DSRC) is defined in the Code of Federal
   Regulations (CFR) 47, Parts 90 and 95.  This Code is referred in the
   definitions below.  At the time of the writing of this Internet
   Draft, the last update of this Code was dated October 1st, 2010.

   DSRCS (Dedicated Short-Range Communications Services): a term defined
   outside the IETF.  The use of radio techniques to transfer data over
   short distances between roadside and mobile units, between mobile
   units, and between portable and mobile units to perform operations
   related to the improvement of traffic flow, traffic safety, and other
   intelligent transportation service applications in a variety of
   environments.  DSRCS systems may also transmit status and
   instructional messages related to the units involve.  [Ref. 47 CFR
   90.7 - Definitions]

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   OBU (On-Board Unit): a term defined outside the IETF.  An On-Board
   Unit is a DSRCS transceiver that is normally mounted in or on a
   vehicle, or which in some instances may be a portable unit.  An OBU
   can be operational while a vehicle or person is either mobile or
   stationary.  The OBUs receive and contend for time to transmit on one
   or more radio frequency (RF) channels.  Except where specifically
   excluded, OBU operation is permitted wherever vehicle operation or
   human passage is permitted.  The OBUs mounted in vehicles are
   licensed by rule under part 95 of the respective chapter and
   communicate with Roadside Units (RSUs) and other OBUs.  Portable OBUs
   are also licensed by rule under part 95 of the respective chapter.
   OBU operations in the Unlicensed National Information Infrastructure
   (UNII) Bands follow the rules in those bands. - [CFR 90.7 -
   Definitions].

   RSU (Road-Side Unit): a term defined outside of IETF.  A Roadside
   Unit is a DSRC transceiver that is mounted along a road or pedestrian
   passageway.  An RSU may also be mounted on a vehicle or is hand
   carried, but it may only operate when the vehicle or hand- carried
   unit is stationary.  Furthermore, an RSU operating under the
   respectgive part is restricted to the location where it is licensed
   to operate.  However, portable or hand-held RSUs are permitted to
   operate where they do not interfere with a site-licensed operation.
   A RSU broadcasts data to OBUs or exchanges data with OBUs in its
   communications zone.  An RSU also provides channel assignments and
   operating instructions to OBUs in its communications zone, when
   required. - [CFR 90.7 - Definitions].

Authors' Addresses

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

   Phone: +33169089223
   Email: Alexandre.Petrescu@cea.fr

   Nabil Benamar
   Moulay Ismail University
   Morocco

   Phone: +212670832236
   Email: n.benamar@est.umi.ac.ma

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   Jerome Haerri
   Eurecom
   Sophia-Antipolis   06904
   France

   Phone: +33493008134
   Email: Jerome.Haerri@eurecom.fr

   Jong-Hyouk Lee
   Sangmyung University
   31, Sangmyeongdae-gil, Dongnam-gu
   Cheonan   31066
   Republic of Korea

   Email: jonghyouk@smu.ac.kr

   Thierry Ernst
   YoGoKo
   France

   Email: thierry.ernst@yogoko.fr

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