draft-ietf-ipwave-ipv6-over-80211ocb-08.txt   draft-ietf-ipwave-ipv6-over-80211ocb-09.txt 
Network Working Group A. Petrescu Network 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 23, 2018 Moulay Ismail University Expires: April 9, 2018 Moulay Ismail University
J. Haerri J. Haerri
Eurecom Eurecom
C. Huitema
Private Octopus Inc.
J. Lee J. Lee
Sangmyung University Sangmyung University
T. Ernst T. Ernst
YoGoKo YoGoKo
T. Li October 6, 2017
Peloton Technology
September 19, 2017
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-08.txt draft-ietf-ipwave-ipv6-over-80211ocb-09.txt
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
similarly to other known 802.11 and Ethernet layers - by using an similarly to other known 802.11 and Ethernet layers - by using an
Ethernet Adaptation Layer. Ethernet Adaptation Layer.
In addition, the document lists what is different in 802.11-OCB
(802.11p) links compared to more 'traditional' 802.11a/b/g/n links,
where IPv6 protocols operate without issues. Most notably, the
operation outside the context of a BSS (OCB) impacts IPv6 handover
behaviour and IPv6 security.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 23, 2018. This Internet-Draft will expire on April 9, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Communication Scenarios where IEEE 802.11-OCB Links are Used 7 3. Communication Scenarios where IEEE 802.11-OCB Links are Used 4
4. Aspects introduced by the OCB mode to 802.11 . . . . . . . . 7 4. IPv6 over 802.11-OCB . . . . . . . . . . . . . . . . . . . . 5
5. Layering of IPv6 over 802.11-OCB as over Ethernet . . . . . . 11 4.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 5
5.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 11 4.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 11 4.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 6
5.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 12 4.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 8
5.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 14 4.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 8
5.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 14 4.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 8
5.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 14 4.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 8
5.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 15 4.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 8
5.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 16 4.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 9
5.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 17 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 9.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 19 9.2. Informative References . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 22 Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 16
Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 23 Appendix B. 802.11p . . . . . . . . . . . . . . . . . . . . . . 20
Appendix B. Changes Needed on a software driver 802.11a to Appendix C. Aspects introduced by the OCB mode to 802.11 . . . . 20
become a 802.11-OCB driver . . . 28 Appendix D. Changes Needed on a software driver 802.11a to
become a 802.11-OCB driver . . . 25
Appendix E. EPD . . . . . . . . . . . . . . . . . . . . . . . . 26
Appendix F. Design Considerations . . . . . . . . . . . . . . . 26
F.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 27
F.2. Reliability Requirements . . . . . . . . . . . . . . . . 27
F.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 28
F.4. MAC Address Generation . . . . . . . . . . . . . . . . . 29
Appendix C. Design Considerations . . . . . . . . . . . . . . . 29 Appendix G. IEEE 802.11 Messages Transmitted in OCB mode . . . . 29
C.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 29 Appendix H. Implementation Status . . . . . . . . . . . . . . . 29
C.2. Reliability Requirements . . . . . . . . . . . . . . . . 30 H.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 30
C.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 30 H.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 33
C.4. MAC Address Generation . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
Appendix D. IEEE 802.11 Messages Transmitted in OCB mode . . . . 32
Appendix E. Implementation Status . . . . . . . . . . . . . . . 32
E.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 33
E.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
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 (a.k.a 802.11p) [IEEE-802.11-2016]. This 802.11-OCB networks [IEEE-802.11-2016] (a.k.a "802.11p" see
involves the layering of IPv6 networking on top of the IEEE 802.11 Appendix B). This involves the layering of IPv6 networking on top of
MAC layer (with an LLC layer). Compared to running IPv6 over the the IEEE 802.11 MAC layer, with an LLC layer. Compared to running
Ethernet MAC layer, there is no modification expected to IEEE Std IPv6 over the Ethernet MAC layer, there is no modification expected
802.11 MAC and Logical Link sublayers: IPv6 works fine directly over to IEEE Std 802.11 MAC and Logical Link sublayers: IPv6 works fine
802.11-OCB too (with an LLC layer). directly over 802.11-OCB too, with an LLC layer.
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 Management Information Base (MIB)
attribute "OCBActivated". 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.
The IPv6 network layer operates on 802.11-OCB in the same manner as The IPv6 network layer operates on 802.11-OCB in the same manner as
it operates on 802.11 WiFi, with a few particular exceptions. The operating on Ethernet, but there are two kinds of exceptions:
IPv6 network layer operates on WiFi by involving an Ethernet
Adaptation Layer; this Ethernet Adaptation Layer maps 802.11 headers
to Ethernet II headers. The operation of IP on Ethernet is described
in [RFC1042], [RFC2464] and [I-D.hinden-6man-rfc2464bis]. The
situation of IPv6 networking layer on Ethernet Adaptation Layer is
illustrated below:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Adaptation Layer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 802.11 WiFi MAC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 802.11 WiFi PHY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(in the above figure, a WiFi profile is represented; this is used
also for OCB profile.)
A more theoretical and detailed view of layer stacking, and
interfaces between the IP layer and 802.11-OCB layers, is illustrated
below. 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).
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In addition to the description of interface between IP and MAC using
"Ethernet Adaptation Layer" and "Ethernet Protocol Discrimination
(EPD)" it is worth mentioning that SNAP [RFC1042] is used to carry
the IPv6 Ethertype.
However, there may be some deployment considerations helping optimize
the performances of running IPv6 over 802.11-OCB (e.g. in the case of
handovers between 802.11-OCB-enabled access routers, or the
consideration of using the IP security architecture [RFC4301]).
There are currently no specifications for handover between OCB links
since these are currently specified as LLC-1 links (i.e.
connectionless). Any handovers must be performed above the Data Link
Layer. To realize handovers between OCB links there is a need for
specific indicators to assist in the handover process. The
indicators may be IP Router Advertisements, or 802.11-OCB's Time
Advertisements, or application-layer data. However, this document
does not describe handover behaviour.
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. See the
section Security Considerations of this document, Section 6
We briefly introduce the vehicular communication scenarios where IEEE
802.11-OCB links are used. This is followed by a description of
differences in specification terms, between 802.11-OCB and
802.11a/b/g/n - we answer the question of what are the aspects
introduced by OCB mode to 802.11; the same aspects, but expressed in
terms of requirements to implementation, are listed in Appendix B.)
The document then concentrates on the parameters of layering IP over o Exceptions due to different operation of IPv6 network layer on
802.11-OCB as over Ethernet: value of MTU, the Frame Format which 802.11 than on Ethernet. To satisfy these exceptions, this
includes a description of an Ethernet Adaptation Layer, the forming document describes an Ethernet Adaptation Layer between Ethernet
of Link-Local Addresses the rules for forming Interface Identifiers headers and 802.11 headers. The Ethernet Adaptation Layer is
for Stateless Autoconfiguration, the mechanisms for Address Mapping. described Section 4.2.1. The operation of IP on Ethernet is
These are precisely the same as IPv6 over Ethernet [RFC2464]. A described in [RFC1042], [RFC2464] and
reference is made to ad-hoc networking characteristics of the subnet [I-D.hinden-6man-rfc2464bis].
structure in OCB mode.
As an example, these characteristics of layering IPv6 straight over o Exceptions due to the OCB nature of 802.11-OCB compared to 802.11.
LLC over 802.11-OCB MAC are illustrated by dissecting an IPv6 packet This has impacts on security, privacy, subnet structure and
captured over a 802.11-OCB link; this is described in the section handover behaviour. For security and privacy recommendations see
Appendix E. Section 5 and Section 4.5. The subnet structure is described in
Section 4.6; a new Group ID is requested to be used in such
subnets, see section Section 6. The handover behaviour on OCB
links is not described in this document.
In the published literature, many documents describe aspects related In the published literature, many documents describe aspects and
to running IPv6 over 802.11-OCB: problems related to running IPv6 over 802.11-OCB:
[I-D.jeong-ipwave-vehicular-networking-survey]. [I-D.ietf-ipwave-vehicular-networking-survey].
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"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].
WiFi: Wireless Fidelity.
OBRU (On-Board Router Unit): an OBRU is almost always situated in a OBRU (On-Board Router Unit): an OBRU is almost always situated in a
vehicle; it is a computer with at least two IP interfaces; at least vehicle; it is a computer with at least two IP interfaces; at least
one IP interface runs in OCB mode of 802.11. It MAY be an IP Router. one IP interface runs in OCB mode of 802.11. It MAY be an IP Router.
RSRU (Road-Side Router Unit): an RSRU is almost always situated in a RSRU (Road-Side Router Unit): an RSRU is almost always situated in a
box fixed along the road. An RSRU has at least two distinct IP- box fixed along the road. An RSRU has at least two distinct IP-
enabled interfaces; at least one interface is operated in mode OCB of enabled interfaces; at least one interface is operated in mode OCB of
IEEE 802.11 and is IP-enabled. An RSRU is similar to a Wireless IEEE 802.11 and is IP-enabled. An RSRU is similar to a Wireless
Termination Point (WTP), as defined in [RFC5415], or an Access Point Termination Point (WTP), as defined in [RFC5415], or an Access Point
(AP), as defined in IEEE documents, or an Access Network Router (ANR) (AP), as defined in IEEE documents, or an Access Network Router (ANR)
defined in [RFC3753], with one key particularity: the wireless PHY/ defined in [RFC3753], with one key particularity: the wireless PHY/
MAC layer of at least one of its IP-enabled interfaces is configured MAC layer of at least one of its IP-enabled interfaces is configured
to operate in 802.11-OCB mode. The RSRU communicates with the On to operate in 802.11-OCB mode. The RSRU communicates with the On
board Unit (OBRU) in the vehicle over 802.11 wireless link operating board Unit (OBRU) in the vehicle over 802.11 wireless link operating
in OCB mode. An RSRU MAY be connected to the Internet, and MAY be an in OCB mode. An RSRU MAY be connected to the Internet, and MAY be an
IP Router. When it is connected to the Internet, the term V2I IP Router. When it is connected to the Internet, the term V2I
(Vehicle to Internet) is relevant. (Vehicle to Internet) is relevant.
RSU (Road-Side Unit): an RSU operates in 802.11-OCB mode. A RSU RSU (Road-Side Unit): an RSU operates in 802.11-OCB mode. A RSU
broadcasts data to OBUs or exchanges data with OBUs in its broadcasts data to OBUs or exchanges data with OBUs in its
communications zone. An RSU may provides channel assignments and communications zone. An RSU may provide channel assignments and
operating instructions to OBUs in its communications zone, when operating instructions to OBUs in its communications zone, when
required. The basic functional blocks of an RSU are: internal required. The basic functional blocks of an RSU are: internal
computer processing, permanent storage capability, an integrated GPS computer processing, permanent storage capability, an integrated GPS
receiver for positioning and timing and an interface that supports receiver for positioning and timing and an interface that supports
both IPv4 and IPv6 connectivity, compliant with 802.3at. An OCB both IPv4 and IPv6 connectivity, compliant with 802.3at. An OCB
interface of an RSU MAY be IP-enabled simultaneously to being WAVE- interface of an RSU MAY be IP-enabled simultaneously to being WAVE-
enabled or GeoNetworking-enabled (MAY support simultaneously enabled or GeoNetworking-enabled (MAY support simultaneously
EtherTypes 0x86DD for IPv6 _and_ 0x88DC for WAVE and 0x8947 for EtherTypes 0x86DD for IPv6 _and_ 0x88DC for WAVE and 0x8947 for
GeoNetworking). GeoNetworking).
skipping to change at page 7, line 25 skipping to change at page 5, line 19
vehicular networks, STAs can be RSRUs and/or OBRUs. While 802.11-OCB vehicular networks, STAs can be RSRUs and/or OBRUs. While 802.11-OCB
is clearly specified, and the use of IPv6 over such link is not is clearly specified, and the use of IPv6 over such link is not
radically new, the operating environment (vehicular networks) brings radically new, the operating environment (vehicular networks) brings
in new perspectives. in new perspectives.
The 802.11-OCB links form and terminate; nodes connected to these The 802.11-OCB links form and terminate; nodes connected to these
links peer, and discover each other; the nodes are mobile. However, links peer, and discover each other; the nodes are mobile. However,
the precise description of how links discover each other, peer and the precise description of how links discover each other, peer and
manage mobility is not given in this document. manage mobility is not given in this document.
4. Aspects introduced by the OCB mode to 802.11 4. IPv6 over 802.11-OCB
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. At link layer, it is necessary to set the
same channel number (or frequency) on two stations that need to
communicate with each other. Stations STA1 and STA2 can exchange IP
packets if they are set on the same channel. At IP layer, they then
discover each other by using the IPv6 Neighbor Discovery protocol.
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 (OBRU and RSRU)
receive all the messages transmitted (OBRU and RSRU) within the radio
communications range. The eventual conflict(s) are resolved by the
MAC CDMA function.
The following message exchange diagram 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 D.
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 -------->|
(a) 802.11 Infrastructure mode (b) 802.11-OCB mode
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 included 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
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 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 WiFi and Ethernet
layers do (802.11a/b/g/n and 802.3). A packet sent by an OBRU may be
received by one or multiple RSRUs. 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; codint 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 -
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, 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
autorization is required; for an onboard device a 'licensed-by-
rule' concept applies: rule certification conformity is required);
however technical conditions are different than those of the bands
"2.4GHz" or "5GHz". On one hand, 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. On the other
hand, 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
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 Section 6. A relevant function is
described in IEEE 1609.3-2016 [IEEE-1609.3], clause 5.5.1 and IEEE
1609.4-2016 [IEEE-1609.4], clause 6.7.
Other aspects particular to 802.11-OCB, which are also particular to
802.11 (e.g. the 'hidden node' operation), may have an influence on
the use of transmission of IPv6 packets on 802.11-OCB networks. The
OCB subnet structure is described in section Section 5.6.
5. Layering of IPv6 over 802.11-OCB as over Ethernet
5.1. Maximum Transmission Unit (MTU) 4.1. Maximum Transmission Unit (MTU)
The default MTU for IP packets on 802.11-OCB is 1500 octets. It is The default MTU for IP packets on 802.11-OCB is 1500 octets. It is
the same value as IPv6 packets on Ethernet links, as specified in the same value as IPv6 packets on Ethernet links, as specified in
[RFC2464]. This value of the MTU respects the recommendation that [RFC2464]. This value of the MTU respects the recommendation that
every link in the Internet must have a minimum MTU of 1280 octets every link on the Internet must have a minimum MTU of 1280 octets
(stated in [RFC8200], and the recommendations therein, especially (stated in [RFC8200], and the recommendations therein, especially
with respect to fragmentation). If IPv6 packets of size larger than with respect to fragmentation). If IPv6 packets of size larger than
1500 bytes are sent on an 802.11-OCB interface card then the IP stack 1500 bytes are sent on an 802.11-OCB interface card then the IP stack
will fragment. In case there are IP fragments, the field "Sequence will fragment. In case there are IP fragments, the field "Sequence
number" of the 802.11 Data header containing the IP fragment field is number" of the 802.11 Data header containing the IP fragment field is
increased. increased.
Non-IP packets such as WAVE Short Message Protocol (WSMP) can be Non-IP packets such as WAVE Short Message Protocol (WSMP) can be
delivered on 802.11-OCB links. Specifications of these packets are delivered on 802.11-OCB links. Specifications of these packets are
out of scope of this document, and do not impose any limit on the MTU out of scope of this document, and do not impose any limit on the MTU
size, allowing an arbitrary number of 'containers'. Non-IP packets size, allowing an arbitrary number of 'containers'. Non-IP packets
such as ETSI GeoNetworking packets have an MTU of 1492 bytes. The such as ETSI GeoNetworking packets have an MTU of 1492 bytes. The
operation of IPv6 over GeoNetworking is specified at operation of IPv6 over GeoNetworking is specified at
[ETSI-IPv6-GeoNetworking]. [ETSI-IPv6-GeoNetworking].
5.2. Frame Format 4.2. Frame Format
IP packets are transmitted over 802.11-OCB as standard Ethernet IP packets are transmitted over 802.11-OCB as standard Ethernet
packets. As with all 802.11 frames, an Ethernet adaptation layer is packets. As with all 802.11 frames, an Ethernet adaptation layer is
used with 802.11-OCB as well. This Ethernet Adaptation Layer used with 802.11-OCB as well. This Ethernet Adaptation Layer
performing 802.11-to-Ethernet is described in Section 5.2.1. The performing 802.11-to-Ethernet is described in Section 4.2.1. The
Ethernet Type code (EtherType) for IPv6 is 0x86DD (hexadecimal 86DD, Ethernet Type code (EtherType) for IPv6 is 0x86DD (hexadecimal 86DD,
or otherwise #86DD). or otherwise #86DD).
The Frame format for transmitting IPv6 on 802.11-OCB networks is the The Frame format for transmitting IPv6 on 802.11-OCB networks is the
same as transmitting IPv6 on Ethernet networks, and is described in same as transmitting IPv6 on Ethernet networks, and is described in
section 3 of [RFC2464]. The frame format for transmitting IPv6 section 3 of [RFC2464].
packets over Ethernet is illustrated below:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 |
+- -+
| header |
+- -+
| and |
+- -+
/ payload ... /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(Each tic mark represents one bit.)
Ethernet II Fields:
Destination Ethernet Address
the MAC destination address.
Source Ethernet Address
the MAC source address.
1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1 1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1
binary representation of the EtherType value 0x86DD. is the binary representation of the EtherType value 0x86DD.
IPv6 header and payload
the IPv6 packet containing IPv6 header and payload.
5.2.1. Ethernet Adaptation Layer 4.2.1. Ethernet Adaptation Layer
In general, an 'adaptation' layer is inserted between a MAC layer and An 'adaptation' layer is inserted between a MAC layer and the
the Networking layer. This is used to transform some parameters Networking layer. This is used to transform some parameters between
between their form expected by the IP stack and the form provided by their form expected by the IP stack and the form provided by the MAC
the MAC layer. For example, an 802.15.4 adaptation layer may perform layer.
fragmentation and reassembly operations on a MAC whose maximum Packet
Data Unit size is smaller than the minimum MTU recognized by the IPv6
Networking layer. Other examples involve link-layer address
transformation, packet header insertion/removal, and so on.
An Ethernet Adaptation Layer makes an 802.11 MAC look to IP An Ethernet Adaptation Layer makes an 802.11 MAC look to IP
Networking layer as a more traditional Ethernet layer. At reception, Networking layer as a more traditional Ethernet layer. At reception,
this layer takes as input the IEEE 802.11 Data Header and the this layer takes as input the IEEE 802.11 Data Header and the
Logical-Link Layer Control Header and produces an Ethernet II Header. Logical-Link Layer Control Header and produces an Ethernet II Header.
At sending, the reverse operation is performed. At sending, the reverse operation is performed.
+--------------------+------------+-------------+---------+-----------+ +--------------------+------------+-------------+---------+-----------+
| 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer|
+--------------------+------------+-------------+---------+-----------+ +--------------------+------------+-------------+---------+-----------+
\ / \ / \ / \ /
----------------------------- -------- ----------------------------- --------
^---------------------------------------------/ \---------------------------------------------/
| ^
802.11-to-Ethernet Adaptation Layer |
| 802.11-to-Ethernet Adaptation Layer
v |
v
+---------------------+-------------+---------+ +---------------------+-------------+---------+
| Ethernet II Header | IPv6 Header | Payload | | Ethernet II Header | IPv6 Header | Payload |
+---------------------+-------------+---------+ +---------------------+-------------+---------+
The Receiver and Transmitter Address fields in the 802.11 Data Header The Receiver and Transmitter Address fields in the 802.11 Data Header
contain the same values as the Destination and the Source Address contain the same values as the Destination and the Source Address
fields in the Ethernet II Header, respectively. The value of the fields in the Ethernet II Header, respectively. The value of the
Type field in the LLC Header is the same as the value of the Type Type field in the LLC Header is the same as the value of the Type
field in the Ethernet II Header. field in the Ethernet II Header.
The ".11 Trailer" contains solely a 4-byte Frame Check Sequence. The ".11 Trailer" contains solely a 4-byte Frame Check Sequence.
The Ethernet Adaptation Layer performs operations in relation to IP Additionally, the Ethernet Adaptation Layer performs operations in
fragmentation and MTU. One of these operations is briefly described relation to IP fragmentation and MTU. One of these operations is
in section Section 5.1. briefly described in section Section 4.1.
In OCB mode, IPv6 packets can be transmitted either as "IEEE 802.11 In OCB mode, IPv6 packets MAY be transmitted either as "IEEE 802.11
Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in
the figure below. Some commercial OCB products use 802.11 Data, and the figure below.
others 802.11 QoS data. In the future, both could be used.
+--------------------+-------------+-------------+---------+-----------+ +--------------------+-------------+-------------+---------+-----------+
| 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer|
+--------------------+-------------+-------------+---------+-----------+ +--------------------+-------------+-------------+---------+-----------+
or or
+--------------------+-------------+-------------+---------+-----------+ +--------------------+-------------+-------------+---------+-----------+
| 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload |.11 Trailer| | 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload |.11 Trailer|
+--------------------+-------------+-------------+---------+-----------+ +--------------------+-------------+-------------+---------+-----------+
skipping to change at page 14, line 27 skipping to change at page 7, line 31
802.11 Data header is 0x0020. The value of the field "Type/Subtype" 802.11 Data header is 0x0020. The value of the field "Type/Subtype"
in the 802.11 QoS header is 0x0028. in the 802.11 QoS header is 0x0028.
The mapping between qos-related fields in the IPv6 header (e.g. The mapping between qos-related fields in the IPv6 header (e.g.
"Traffic Class", "Flow label") and fields in the "802.11 QoS Data "Traffic Class", "Flow label") and fields in the "802.11 QoS Data
Header" (e.g. "QoS Control") are not specified in this document. Header" (e.g. "QoS Control") are not specified in this document.
Guidance for a potential mapping is provided in Guidance for a potential mapping is provided in
[I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB [I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB
mode. mode.
5.3. Link-Local Addresses The placement of IPv6 networking layer on Ethernet Adaptation Layer
is illustrated below:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Adaptation Layer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 802.11 WiFi MAC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 802.11 WiFi PHY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(in the above figure, a WiFi profile is represented; this is used
also for OCB profile.)
Other alternative views of layering are EtherType Protocol
Discrimination (EPD), see Appendix E, and SNAP see [RFC1042].
4.3. Link-Local Addresses
The link-local address of an 802.11-OCB interface is formed in the The link-local address of an 802.11-OCB interface is formed in the
same manner as on an Ethernet interface. This manner is described in same manner as on an Ethernet interface. This manner is described in
section 5 of [RFC2464]. Additionally, if stable identifiers are section 5 of [RFC2464]. Additionally, if stable identifiers are
needed, it is recommended to follow the Recommendation on Stable IPv6 needed, it is recommended to follow the Recommendation on Stable IPv6
Interface Identifiers [RFC8064]. Additionally, if semantically Interface Identifiers [RFC8064]. Additionally, if semantically
opaque Interface Identifiers are needed, a potential method for opaque Interface Identifiers are needed, a potential method for
generating semantically opaque Interface Identifiers with IPv6 generating semantically opaque Interface Identifiers with IPv6
Stateless Address Autoconfiguration is given in [RFC7217]. Stateless Address Autoconfiguration is given in [RFC7217].
5.4. Address Mapping 4.4. Address Mapping
For unicast as for multicast, there is no change from the unicast and For unicast as for multicast, there is no change from the unicast and
multicast address mapping format of Ethernet interfaces, as defined multicast address mapping format of Ethernet interfaces, as defined
by sections 6 and 7 of [RFC2464]. by sections 6 and 7 of [RFC2464].
5.4.1. Address Mapping -- Unicast 4.4.1. Address Mapping -- Unicast
The procedure for mapping IPv6 unicast addresses into Ethernet link- The procedure for mapping IPv6 unicast addresses into Ethernet link-
layer addresses is described in [RFC4861]. The Source/Target Link- layer addresses is described in [RFC4861].
layer Address option has the following form when the link-layer is
Ethernet.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- Ethernet -+
| |
+- Address -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option fields:
Type
1 for Source Link-layer address.
2 for Target Link-layer address.
Length
1 (in units of 8 octets).
Ethernet Address
The 48 bit Ethernet IEEE 802 address, in canonical bit order.
5.4.2. Address Mapping -- Multicast
IPv6 protocols often make use of IPv6 multicast addresses in the
destination field of IPv6 headers. For example, an ICMPv6 link-
scoped Neighbor Advertisement is sent to the IPv6 address ff02::1
denoted "all-nodes" address. When transmitting these packets on
802.11-OCB links it is necessary to map the IPv6 address to a MAC
address.
The same mapping requirement applies to the link-scoped multicast
addresses of other IPv6 protocols as well. In DHCPv6, the
"All_DHCP_Servers" IPv6 multicast address ff02::1:2, and in OSPF the
"All_SPF_Routers" IPv6 multicast address ff02::5, need to be mapped
on a multicast MAC address.
An IPv6 packet with a multicast destination address DST, consisting
of the sixteen octets DST[1] through DST[16], is transmitted to the
IEEE 802.11-OCB MAC multicast address whose first two octets are the
value 0x3333 and whose last four octets are the last four octets of
DST.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.4.2. Address Mapping -- Multicast
|0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[13] | DST[14] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[15] | DST[16] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A Group ID named TBD, of length 112bits is requested to IANA; this A Group ID named TBD, of length 112bits is requested to IANA; this
Group ID signifies "All 80211OCB Interfaces Address". Only the least Group ID signifies "All 80211OCB Interfaces Address". Only the least
32 significant bits of this "All 80211OCB Interfaces Address" will be 32 significant bits of this "All 80211OCB Interfaces Address" will be
mapped to and from a MAC multicast address. mapped to and from a MAC multicast address.
Transmitting IPv6 packets to multicast destinations over 802.11 links Transmitting IPv6 packets to multicast destinations over 802.11 links
proved to have some performance issues proved to have some performance issues
[I-D.perkins-intarea-multicast-ieee802]. These issues may be [I-D.perkins-intarea-multicast-ieee802]. These issues may be
exacerbated in OCB mode. Solutions for these problems should exacerbated in OCB mode. Solutions for these problems should
consider the OCB mode of operation. consider the OCB mode of operation.
5.5. Stateless Autoconfiguration 4.5. Stateless Autoconfiguration
The Interface Identifier for an 802.11-OCB interface is formed using The Interface Identifier for an 802.11-OCB interface is formed using
the same rules as the Interface Identifier for an Ethernet interface; the same rules as the Interface Identifier for an Ethernet interface;
this is described in section 4 of [RFC2464]. No changes are needed, this is described in section 4 of [RFC2464]. No changes are needed,
but some care must be taken when considering the use of the SLAAC but some care must be taken when considering the use of the Stateless
procedure. Address Auto-Configuration procedure.
The bits in the the interface identifier have no generic meaning and The bits in the interface identifier have no generic meaning and the
the identifier should be treated as an opaque value. The bits identifier should be treated as an opaque value. The bits
'Universal' and 'Group' in the identifier of an 802.11-OCB interface 'Universal' and 'Group' in the identifier of an 802.11-OCB interface
are significant, as this is an IEEE link-layer address. The details are significant, as this is an IEEE link-layer address. The details
of this significance are described in [RFC7136]. of this significance are described in [RFC7136].
As with all Ethernet and 802.11 interface identifiers ([RFC7721]), As with all Ethernet and 802.11 interface identifiers ([RFC7721]),
the identifier of an 802.11-OCB interface may involve privacy, MAC the identifier of an 802.11-OCB interface may involve privacy, MAC
address spoofing and IP address hijacking risks. A vehicle embarking address spoofing and IP address hijacking risks. A vehicle embarking
an On-Board Unit whose egress interface is 802.11-OCB may expose an On-Board Unit whose egress interface is 802.11-OCB may expose
itself to eavesdropping and subsequent correlation of data; this may itself to eavesdropping and subsequent correlation of data; this may
reveal data considered private by the vehicle owner; there is a risk reveal data considered private by the vehicle owner; there is a risk
of being tracked; see the privacy considerations described in of being tracked; see the privacy considerations described in
Appendix C. Appendix F.
If stable Interface Identifiers are needed in order to form IPv6 If stable Interface Identifiers are needed in order to form IPv6
addresses on 802.11-OCB links, it is recommended to follow the addresses on 802.11-OCB links, it is recommended to follow the
recommendation in [RFC8064]. Additionally, if semantically opaque recommendation in [RFC8064]. Additionally, if semantically opaque
Interface Identifiers are needed, a potential method for generating Interface Identifiers are needed, a potential method for generating
semantically opaque Interface Identifiers with IPv6 Stateless Address semantically opaque Interface Identifiers with IPv6 Stateless Address
Autoconfiguration is given in [RFC7217]. Autoconfiguration is given in [RFC7217].
5.6. Subnet Structure 4.6. Subnet Structure
A subnet is formed by the external 802.11-OCB interfaces of vehicles A subnet is formed by the external 802.11-OCB interfaces of vehicles
that are in close range (not their on-board interfaces). This that are in close range (not their on-board interfaces). This
ephemeral subnet structure is strongly influenced by the mobility of ephemeral subnet structure is strongly influenced by the mobility of
vehicles: the 802.11 hidden node effects appear. On another hand, vehicles: the 802.11 hidden node effects appear. On another hand,
the structure of the internal subnets in each car is relatively the structure of the internal subnets in each car is relatively
stable. stable.
For routing purposes, a prefix exchange mechanism could be needed
between neighboring vehicles.
The 802.11 networks in OCB mode may be considered as 'ad-hoc' The 802.11 networks in OCB mode may be considered as 'ad-hoc'
networks. The addressing model for such networks is described in networks. The addressing model for such networks is described in
[RFC5889]. [RFC5889].
An addressing model involves several types of addresses, like An addressing model involves several types of addresses, like
Globally-unique Addresses (GUA), Link-Local Addresses (LL) and Unique Globally-unique Addresses (GUA), Link-Local Addresses (LL) and Unique
Local Addresses (ULA). The subnet structure in 'ad-hoc' networks may Local Addresses (ULA). The subnet structure in 'ad-hoc' networks may
have characteristics that lead to difficulty of using GUAs derived have characteristics that lead to difficulty of using GUAs derived
from a received prefix, but the LL addresses may be easier to use from a received prefix, but the LL addresses may be easier to use
since the prefix is constant. since the prefix is constant.
6. Security Considerations 5. Security Considerations
Any security mechanism at the IP layer or above that may be carried 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 out for the general case of IPv6 may also be carried out for IPv6
operating over 802.11-OCB. 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 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.
skipping to change at page 18, line 23 skipping to change at page 10, line 42
possibility of attacker sniffers deployed along routes which listen possibility of attacker sniffers deployed along routes which listen
for IP packets of vehicles passing by. For this reason, in the for IP packets of vehicles passing by. For this reason, in the
802.11-OCB deployments, there is a strong necessity to use protection 802.11-OCB deployments, there is a strong necessity to use protection
tools such as dynamically changing MAC addresses. This may help tools such as dynamically changing MAC addresses. This may help
mitigate privacy risks to a certain level. On another hand, it may mitigate privacy risks to a certain level. On another hand, it may
have an impact in the way typical IPv6 address auto-configuration is have an impact in the way typical IPv6 address auto-configuration is
performed for vehicles (SLAAC would rely on MAC addresses amd would performed for vehicles (SLAAC would rely on MAC addresses amd would
hence dynamically change the affected IP address), in the way the hence dynamically change the affected IP address), in the way the
IPv6 Privacy addresses were used, and other effects. IPv6 Privacy addresses were used, and other effects.
7. IANA Considerations 6. IANA Considerations
A Group ID named TBD, of length 112bits is requested to IANA; this A Group ID named TBD, of length 112bits is requested to IANA; this
Group ID signifies "All 80211OCB Interfaces Address". Group ID signifies "All 80211OCB Interfaces Address".
8. Contributors 7. Contributors
Christian Huitema, Tony Li.
Romain Kuntz contributed extensively about IPv6 handovers between Romain Kuntz contributed extensively about IPv6 handovers between
links running outside the context of a BSS (802.11-OCB links). links running outside the context of a BSS (802.11-OCB links).
Tim Leinmueller contributed the idea of the use of IPv6 over Tim Leinmueller contributed the idea of the use of IPv6 over
802.11-OCB for distribution of certificates. 802.11-OCB for distribution of certificates.
Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey
Voronov provided significant feedback on the experience of using IP Voronov provided significant feedback on the experience of using IP
messages over 802.11-OCB in initial trials. messages over 802.11-OCB in initial trials.
Michelle Wetterwald contributed extensively the MTU discussion, Michelle Wetterwald contributed extensively the MTU discussion,
offered the ETSI ITS perspective, and reviewed other parts of the offered the ETSI ITS perspective, and reviewed other parts of the
document. document.
9. Acknowledgements 8. Acknowledgements
The authors would like to thank Witold Klaudel, Ryuji Wakikawa, The authors would like to thank Witold Klaudel, Ryuji Wakikawa,
Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan
Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray
Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan, Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan,
Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne, Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne,
Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, Erik Nordmark, Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, Erik Nordmark,
Bob Moskowitz, Andrew (Dryden?), Georg Mayer, Dorothy Stanley, Sandra Bob Moskowitz, Andrew (Dryden?), Georg Mayer, Dorothy Stanley, Sandra
Cespedes, Mariano Falcitelli, Sri Gundavelli and William Whyte. Cespedes, Mariano Falcitelli, Sri Gundavelli, Abdussalam Baryun,
Their valuable comments clarified particular issues and generally Margaret Cullen and William Whyte. Their valuable comments clarified
helped to improve the document. particular issues and generally helped to improve the document.
Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB
drivers for linux and described how. drivers for linux and described how.
For the multicast discussion, the authors would like to thank Owen For the multicast discussion, the authors would like to thank Owen
DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and
participants to discussions in network working groups. participants to discussions in network working groups.
The authours would like to thank participants to the Birds-of- The authours would like to thank participants to the Birds-of-
a-Feather "Intelligent Transportation Systems" meetings held at IETF a-Feather "Intelligent Transportation Systems" meetings held at IETF
in 2016. in 2016.
10. References 9. References
10.1. Normative References 9.1. Normative References
[I-D.ietf-tsvwg-ieee-802-11] [I-D.ietf-tsvwg-ieee-802-11]
Szigeti, T., Henry, J., and F. Baker, "Diffserv to IEEE Szigeti, T., Henry, J., and F. Baker, "Diffserv to IEEE
802.11 Mapping", draft-ietf-tsvwg-ieee-802-11-09 (work in 802.11 Mapping", draft-ietf-tsvwg-ieee-802-11-09 (work in
progress), September 2017. progress), September 2017.
[RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission
of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, of IP datagrams over IEEE 802 networks", STD 43, RFC 1042,
DOI 10.17487/RFC1042, February 1988, DOI 10.17487/RFC1042, February 1988,
<https://www.rfc-editor.org/info/rfc1042>. <https://www.rfc-editor.org/info/rfc1042>.
skipping to change at page 20, line 5 skipping to change at page 12, line 27
<https://www.rfc-editor.org/info/rfc2464>. <https://www.rfc-editor.org/info/rfc2464>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>. <https://www.rfc-editor.org/info/rfc2818>.
[RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related [RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related
Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004, Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004,
<https://www.rfc-editor.org/info/rfc3753>. <https://www.rfc-editor.org/info/rfc3753>.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, DOI 10.17487/RFC3963, January 2005,
<https://www.rfc-editor.org/info/rfc3963>.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, "SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005, DOI 10.17487/RFC3971, March 2005,
<https://www.rfc-editor.org/info/rfc3971>. <https://www.rfc-editor.org/info/rfc3971>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
skipping to change at page 20, line 38 skipping to change at page 13, line 9
December 2005, <https://www.rfc-editor.org/info/rfc4301>. December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302, [RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005, DOI 10.17487/RFC4302, December 2005,
<https://www.rfc-editor.org/info/rfc4302>. <https://www.rfc-editor.org/info/rfc4302>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005, RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>. <https://www.rfc-editor.org/info/rfc4303>.
[RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD)
for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006,
<https://www.rfc-editor.org/info/rfc4429>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
[RFC5374] Weis, B., Gross, G., and D. Ignjatic, "Multicast [RFC5374] Weis, B., Gross, G., and D. Ignjatic, "Multicast
Extensions to the Security Architecture for the Internet Extensions to the Security Architecture for the Internet
Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008, Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008,
<https://www.rfc-editor.org/info/rfc5374>. <https://www.rfc-editor.org/info/rfc5374>.
skipping to change at page 21, line 19 skipping to change at page 13, line 33
<https://www.rfc-editor.org/info/rfc5415>. <https://www.rfc-editor.org/info/rfc5415>.
[RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing [RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing
Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889, Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889,
September 2010, <https://www.rfc-editor.org/info/rfc5889>. September 2010, <https://www.rfc-editor.org/info/rfc5889>.
[RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
2011, <https://www.rfc-editor.org/info/rfc6275>. 2011, <https://www.rfc-editor.org/info/rfc6275>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>.
[RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6
Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136,
February 2014, <https://www.rfc-editor.org/info/rfc7136>. February 2014, <https://www.rfc-editor.org/info/rfc7136>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque [RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217, Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014, DOI 10.17487/RFC7217, April 2014,
<https://www.rfc-editor.org/info/rfc7217>. <https://www.rfc-editor.org/info/rfc7217>.
skipping to change at page 22, line 5 skipping to change at page 14, line 10
[RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu,
"Recommendation on Stable IPv6 Interface Identifiers", "Recommendation on Stable IPv6 Interface Identifiers",
RFC 8064, DOI 10.17487/RFC8064, February 2017, RFC 8064, DOI 10.17487/RFC8064, February 2017,
<https://www.rfc-editor.org/info/rfc8064>. <https://www.rfc-editor.org/info/rfc8064>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
10.2. Informative References 9.2. Informative References
[ETSI-IPv6-GeoNetworking] [ETSI-IPv6-GeoNetworking]
"ETSI EN 302 636-6-1 v1.2.1 (2014-05), ETSI, European "ETSI EN 302 636-6-1 v1.2.1 (2014-05), ETSI, European
Standard, Intelligent Transportation Systems (ITS); Standard, Intelligent Transportation Systems (ITS);
Vehicular Communications; Geonetworking; Part 6: Internet Vehicular Communications; Geonetworking; Part 6: Internet
Integration; Sub-part 1: Transmission of IPv6 Packets over Integration; Sub-part 1: Transmission of IPv6 Packets over
Geonetworking Protocols. Downloaded on September 9th, Geonetworking Protocols. Downloaded on September 9th,
2017, freely available from ETSI website at URL 2017, freely available from ETSI website at URL
http://www.etsi.org/deliver/ http://www.etsi.org/deliver/
etsi_en/302600_302699/30263601/01.02.01_60/ etsi_en/302600_302699/30263601/01.02.01_60/
skipping to change at page 22, line 33 skipping to change at page 14, line 38
September 9th, 2017, freely available from ETSI website at September 9th, 2017, freely available from ETSI website at
URL http://www.etsi.org/deliver/ URL http://www.etsi.org/deliver/
etsi_ts/102900_102999/102940/01.02.01_60/ etsi_ts/102900_102999/102940/01.02.01_60/
ts_102940v010201p.pdf". ts_102940v010201p.pdf".
[I-D.hinden-6man-rfc2464bis] [I-D.hinden-6man-rfc2464bis]
Crawford, M. and R. Hinden, "Transmission of IPv6 Packets Crawford, M. and R. Hinden, "Transmission of IPv6 Packets
over Ethernet Networks", draft-hinden-6man-rfc2464bis-02 over Ethernet Networks", draft-hinden-6man-rfc2464bis-02
(work in progress), March 2017. (work in progress), March 2017.
[I-D.jeong-ipwave-vehicular-networking-survey] [I-D.ietf-ipwave-vehicular-networking-survey]
Jeong, J., Cespedes, S., Benamar, N., Haerri, J., and M. Jeong, J., Cespedes, S., Benamar, N., Haerri, J., and M.
Wetterwald, "Survey on IP-based Vehicular Networking for Wetterwald, "Survey on IP-based Vehicular Networking for
Intelligent Transportation Systems", draft-jeong-ipwave- Intelligent Transportation Systems", draft-ietf-ipwave-
vehicular-networking-survey-03 (work in progress), June vehicular-networking-survey-00 (work in progress), July
2017. 2017.
[I-D.perkins-intarea-multicast-ieee802] [I-D.perkins-intarea-multicast-ieee802]
Perkins, C., Stanley, D., Kumari, W., and J. Zuniga, Perkins, C., Stanley, D., Kumari, W., and J. Zuniga,
"Multicast Considerations over IEEE 802 Wireless Media", "Multicast Considerations over IEEE 802 Wireless Media",
draft-perkins-intarea-multicast-ieee802-03 (work in draft-perkins-intarea-multicast-ieee802-03 (work in
progress), July 2017. progress), July 2017.
[I-D.petrescu-its-scenarios-reqs] [I-D.petrescu-its-scenarios-reqs]
Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel, Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel,
skipping to change at page 24, line 5 skipping to change at page 16, line 10
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.
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.
From draft-ietf-ipwave-ipv6-over-80211ocb-07 to draft-ietf-ipwave- From draft-ietf-ipwave-ipv6-over-80211ocb-07 to draft-ietf-ipwave-
ipv6-over-80211ocb-08 ipv6-over-80211ocb-08
o Removed the per-channel IPv6 prohibition text. o Removed the per-channel IPv6 prohibition text.
o Corrected typographical errors. o Corrected typographical errors.
From draft-ietf-ipwave-ipv6-over-80211ocb-06 to draft-ietf-ipwave- From draft-ietf-ipwave-ipv6-over-80211ocb-06 to draft-ietf-ipwave-
ipv6-over-80211ocb-07 ipv6-over-80211ocb-07
skipping to change at page 28, line 5 skipping to change at page 20, line 35
o Clarified the definition of a Road Side Unit. o Clarified the definition of a Road Side Unit.
o Removed the discussion about security of WSA (because is non-IP). o Removed the discussion about security of WSA (because is non-IP).
o Removed mentioning of the GeoNetworking discussion. o Removed mentioning of the GeoNetworking discussion.
o Moved references to scientific articles to a separate 'overview' o Moved references to scientific articles to a separate 'overview'
draft, and referred to it. draft, and referred to it.
Appendix B. Changes Needed on a software driver 802.11a to become a 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 Management Information Base (MIB)
attribute "OCBActivated". 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. At link layer, it is necessary to set the
same channel number (or frequency) on two stations that need to
communicate with each other. Stations STA1 and STA2 can exchange IP
packets if they are set on the same channel. At IP layer, they then
discover each other by using the IPv6 Neighbor Discovery protocol.
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 (OBRU and RSRU)
receive all the messages transmitted (OBRU and RSRU) within the radio
communications range. The eventual conflict(s) are resolved by the
MAC CDMA function.
The following message exchange diagram 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 -------->|
(a) 802.11 Infrastructure mode (b) 802.11-OCB mode
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 included 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
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 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 WiFi and Ethernet
layers do (802.11a/b/g/n and 802.3). A packet sent by an OBRU may be
received by one or multiple RSRUs. 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; codint 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 -
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, 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
autorization is required; for an onboard device a 'licensed-by-
rule' concept applies: rule certification conformity is required);
however technical conditions are different than those of the bands
"2.4GHz" or "5GHz". On one hand, 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. On the other
hand, 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
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 Section 5. A relevant function is
described in IEEE 1609.3-2016 [IEEE-1609.3], clause 5.5.1 and IEEE
1609.4-2016 [IEEE-1609.4], clause 6.7.
Other aspects particular to 802.11-OCB, which are also particular to
802.11 (e.g. the 'hidden node' operation), may have an influence on
the use of transmission of IPv6 packets on 802.11-OCB networks. The
OCB subnet structure is described in section Section 4.6.
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:
o The PHY entity shall be an orthogonal frequency division o The PHY entity shall be an orthogonal frequency division
multiplexing (OFDM) system. It must support the frequency bands multiplexing (OFDM) system. It must support the frequency bands
skipping to change at page 29, line 21 skipping to change at page 26, line 21
Response) and for authentication (Authentication Request/Reply, Response) and for authentication (Authentication Request/Reply,
Challenge) are not called. Challenge) are not called.
* The beacon interval is always set to 0 (zero). * The beacon interval is always set to 0 (zero).
* Timing Advertisement frames, defined in the amendment, should * Timing Advertisement frames, defined in the amendment, should
be supported. The upper layer should be able to trigger such be supported. The upper layer should be able to trigger such
frames emission and to retrieve information contained in frames emission and to retrieve information contained in
received Timing Advertisements. received Timing Advertisements.
Appendix C. Design Considerations Appendix E. EPD
A more theoretical and detailed view of layer stacking, and
interfaces between the IP layer and 802.11-OCB layers, is illustrated
below. 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).
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Appendix F. Design Considerations
The networks defined by 802.11-OCB are in many ways similar to other 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 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 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, other networks of the 802.11 family. However, the high mobility,
strong link asymmetry and very short connection makes the 802.11-OCB strong link asymmetry and very short connection makes the 802.11-OCB
link significantly different from other 802.11 networks. Also, the link significantly different from other 802.11 networks. Also, the
automotive applications have specific requirements for reliability, automotive applications have specific requirements for reliability,
security and privacy, which further add to the particularity of the security and privacy, which further add to the particularity of the
802.11-OCB link. 802.11-OCB link.
C.1. Vehicle ID F.1. Vehicle ID
In automotive networks it is required that each node is represented In automotive networks it is required that each node is represented
uniquely. Accordingly, a vehicle must be identified by at least one uniquely. Accordingly, a vehicle must be identified by at least one
unique identifier. The current specification at ETSI and at IEEE unique identifier. The current specification at ETSI and at IEEE
1609 identifies a vehicle by its MAC address, which is obtained from 1609 identifies a vehicle by its MAC address, which is obtained from
the 802.11-OCB Network Interface Card (NIC). the 802.11-OCB Network Interface Card (NIC).
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.
C.2. Reliability Requirements F.2. Reliability Requirements
This section may need to be moved out into a separate requirements This section may need to be moved out into a separate requirements
document. document.
The dynamically changing topology, short connectivity, mobile The dynamically changing topology, short connectivity, mobile
transmitter and receivers, different antenna heights, and many-to- transmitter and receivers, different antenna heights, and many-to-
many communication types, make IEEE 802.11-OCB links significantly many communication types, make IEEE 802.11-OCB links significantly
different from other IEEE 802.11 links. Any IPv6 mechanism operating different from other IEEE 802.11 links. Any IPv6 mechanism operating
on IEEE 802.11-OCB link MUST support strong link asymmetry, spatio- on IEEE 802.11-OCB link MUST support strong link asymmetry, spatio-
temporal link quality, fast address resolution and transmission. temporal link quality, fast address resolution and transmission.
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between transmitters and receivers without the support of a NTP between transmitters and receivers without the support of a NTP
server. server.
The IEEE 802.11-OCB link being asymmetric, IPv6 over IEEE 802.11-OCB The IEEE 802.11-OCB link being asymmetric, IPv6 over IEEE 802.11-OCB
MUST disable management mechanisms requesting acknowledgements or MUST disable management mechanisms requesting acknowledgements or
replies. replies.
The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE
802.11-OCB SHOULD implement fast IPv6 mobility management mechanisms. 802.11-OCB SHOULD implement fast IPv6 mobility management mechanisms.
C.3. Multiple interfaces F.3. Multiple interfaces
There are considerations for 2 or more IEEE 802.11-OCB interface There are considerations for 2 or more IEEE 802.11-OCB interface
cards per vehicle. For each vehicle taking part in road traffic, one 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 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 safety-critical communication. Any other IEEE 802.11-OCB may be used
for other type of traffic. for other type of traffic.
The mode of operation of these other wireless interfaces is not The mode of operation of these other wireless interfaces is not
clearly defined yet. One possibility is to consider each card as an clearly defined yet. One possibility is to consider each card as an
independent network interface, with a specific MAC Address and a set independent network interface, with a specific MAC Address and a set
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are represented by many network interface, a single renumbering event are represented by many network interface, a single renumbering event
SHALL cause renumbering of all these interfaces. If one MAC changed SHALL cause renumbering of all these interfaces. If one MAC changed
and another stayed constant, external observers would be able to and another stayed constant, external observers would be able to
correlate old and new values, and the privacy benefits of correlate old and new values, and the privacy benefits of
randomization would be lost. randomization would be lost.
The privacy requirements of Non IP safety-critical communications The privacy requirements of Non IP safety-critical communications
imply that if a change of pseudonyme occurs, renumbering of all other imply that if a change of pseudonyme occurs, renumbering of all other
interfaces SHALL also occur. interfaces SHALL also occur.
C.4. MAC Address Generation F.4. MAC Address Generation
When designing the IPv6 over 802.11-OCB address mapping, we will When designing the IPv6 over 802.11-OCB address mapping, we will
assume that the MAC Addresses will change during well defined assume that the MAC Addresses will change during well defined
"renumbering events". The 48 bits randomized MAC addresses will have "renumbering events". The 48 bits randomized MAC addresses will have
the following characteristics: the following characteristics:
o Bit "Local/Global" set to "locally admninistered". o Bit "Local/Global" set to "locally admninistered".
o Bit "Unicast/Multicast" set to "Unicast". o Bit "Unicast/Multicast" set to "Unicast".
o 46 remaining bits set to a random value, using a random number o 46 remaining bits set to a random value, using a random number
generator that meets the requirements of [RFC4086]. generator that meets the requirements of [RFC4086].
The way to meet the randomization requirements is to retain 46 bits The way to meet the randomization requirements is to retain 46 bits
from the output of a strong hash function, such as SHA256, taking as from the output of a strong hash function, such as SHA256, taking as
input a 256 bit local secret, the "nominal" MAC Address of the input a 256 bit local secret, the "nominal" MAC Address of the
interface, and a representation of the date and time of the interface, and a representation of the date and time of the
renumbering event. renumbering event.
Appendix D. 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,
CF-End, and CF-End plus CFAck; CF-End, and CF-End plus CFAck;
o The STA may send data frames of subtype Data, Null, QoS Data, and o The STA may send data frames of subtype Data, Null, QoS Data, and
QoS Null. QoS Null.
Appendix E. Implementation Status Appendix H. Implementation Status
This section describes an example of an IPv6 Packet captured over a This section describes an example of an IPv6 Packet captured over a
IEEE 802.11-OCB link. IEEE 802.11-OCB link.
By way of example we show that there is no modification in the By way of example we show that there is no modification in the
headers when transmitted over 802.11-OCB networks - they are headers when transmitted over 802.11-OCB networks - they are
transmitted like any other 802.11 and Ethernet packets. transmitted like any other 802.11 and Ethernet packets.
We describe an experiment of capturing an IPv6 packet on an We describe an experiment of capturing an IPv6 packet on an
802.11-OCB link. In this experiment, the packet is an IPv6 Router 802.11-OCB link. In this experiment, the packet is an IPv6 Router
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During several capture operations running from a few moments to During several capture operations running from a few moments to
several hours, no message relevant to the BSSID contexts were several hours, no message relevant to the BSSID contexts were
captured (no Association Request/Response, Authentication Req/Resp, captured (no Association Request/Response, Authentication Req/Resp,
Beacon). This shows that the operation of 802.11-OCB is outside the Beacon). This shows that the operation of 802.11-OCB is outside the
context of a BSSID. context of a BSSID.
Overall, the captured message is identical with a capture of an IPv6 Overall, the captured message is identical with a capture of an IPv6
packet emitted on a 802.11b interface. The contents are precisely packet emitted on a 802.11b interface. The contents are precisely
similar. similar.
E.1. Capture in Monitor Mode H.1. Capture in Monitor Mode
The IPv6 RA packet captured in monitor mode is illustrated below. The IPv6 RA packet captured in monitor mode is illustrated below.
The radio tap header provides more flexibility for reporting the The radio tap header provides more flexibility for reporting the
characteristics of frames. The Radiotap Header is prepended by this characteristics of frames. The Radiotap Header is prepended by this
particular stack and operating system on the Host machine to the RA particular stack and operating system on the Host machine to the RA
packet received from the network (the Radiotap Header is not present packet received from the network (the Radiotap Header is not present
on the air). The implementation-dependent Radiotap Header is useful on the air). The implementation-dependent Radiotap Header is useful
for piggybacking PHY information from the chip's registers as data in for piggybacking PHY information from the chip's registers as data in
a packet understandable by userland applications using Socket a packet understandable by userland applications using Socket
interfaces (the PHY interface can be, for example: power levels, data interfaces (the PHY interface can be, for example: power levels, data
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the IEEE 802.11 data, the destination address is 33:33:00:00:00:01 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 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 broadcast address of ff:ff:ff:ff:ff:ff. Due to the short link
duration between vehicles and the roadside infrastructure, there is duration between vehicles and the roadside infrastructure, there is
no need in IEEE 802.11-OCB to wait for the completion of association no need in IEEE 802.11-OCB to wait for the completion of association
and authentication procedures before exchanging data. IEEE and authentication procedures before exchanging data. IEEE
802.11-OCB enabled nodes use the wildcard BSSID (a value of all 1s) 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 and may start communicating as soon as they arrive on the
communication channel. communication channel.
E.2. Capture in Normal Mode H.2. Capture in Normal Mode
The same IPv6 Router Advertisement packet described above (monitor The same IPv6 Router Advertisement packet described above (monitor
mode) is captured on the Host, in the Normal mode, and depicted mode) is captured on the Host, in the Normal mode, and depicted
below. below.
Ethernet II Header Ethernet II Header
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination... | Destination...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...Destination | Source... ...Destination | Source...
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Phone: +212670832236 Phone: +212670832236
Email: benamar73@gmail.com Email: benamar73@gmail.com
Jerome Haerri Jerome Haerri
Eurecom Eurecom
Sophia-Antipolis 06904 Sophia-Antipolis 06904
France France
Phone: +33493008134 Phone: +33493008134
Email: Jerome.Haerri@eurecom.fr Email: Jerome.Haerri@eurecom.fr
Christian Huitema
Private Octopus Inc.
Friday Harbor, WA 98250
U.S.A.
Email: huitema@huitema.net
Jong-Hyouk Lee Jong-Hyouk Lee
Sangmyung University Sangmyung University
31, Sangmyeongdae-gil, Dongnam-gu 31, Sangmyeongdae-gil, Dongnam-gu
Cheonan 31066 Cheonan 31066
Republic of Korea Republic of Korea
Email: jonghyouk@smu.ac.kr Email: jonghyouk@smu.ac.kr
Thierry Ernst Thierry Ernst
YoGoKo YoGoKo
France France
Email: thierry.ernst@yogoko.fr Email: thierry.ernst@yogoko.fr
Tony Li
Peloton Technology
1060 La Avenida St.
Mountain View, California 94043
United States
Phone: +16503957356
Email: tony.li@tony.li
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