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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Petrescu 3 Internet-Draft CEA, LIST 4 Intended status: Standards Track N. Benamar 5 Expires: March 21, 2018 Moulay Ismail University 6 J. Haerri 7 Eurecom 8 C. Huitema 9 Private Octopus Inc. 10 J. Lee 11 Sangmyung University 12 T. Ernst 13 YoGoKo 14 T. Li 15 Peloton Technology 16 September 17, 2017 18 Transmission of IPv6 Packets over IEEE 802.11 Networks operating in mode 19 Outside the Context of a Basic Service Set (IPv6-over-80211-OCB) 20 draft-ietf-ipwave-ipv6-over-80211ocb-07.txt 22 Abstract 24 In order to transmit IPv6 packets on IEEE 802.11 networks running 25 outside the context of a basic service set (OCB, earlier "802.11p") 26 there is a need to define a few parameters such as the supported 27 Maximum Transmission Unit size on the 802.11-OCB link, the header 28 format preceding the IPv6 header, the Type value within it, and 29 others. This document describes these parameters for IPv6 and IEEE 30 802.11-OCB networks; it portrays the layering of IPv6 on 802.11-OCB 31 similarly to other known 802.11 and Ethernet layers - by using an 32 Ethernet Adaptation Layer. 34 In addition, the document lists what is different in 802.11-OCB 35 (802.11p) links compared to more 'traditional' 802.11a/b/g/n links, 36 where IPv6 protocols operate without issues. Most notably, the 37 operation outside the context of a BSS (OCB) impacts IPv6 handover 38 behaviour and IPv6 security. 40 Status of This Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF). Note that other groups may also distribute 47 working documents as Internet-Drafts. The list of current Internet- 48 Drafts is at https://datatracker.ietf.org/drafts/current/. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 This Internet-Draft will expire on March 21, 2018. 57 Copyright Notice 59 Copyright (c) 2017 IETF Trust and the persons identified as the 60 document authors. All rights reserved. 62 This document is subject to BCP 78 and the IETF Trust's Legal 63 Provisions Relating to IETF Documents 64 (https://trustee.ietf.org/license-info) in effect on the date of 65 publication of this document. Please review these documents 66 carefully, as they describe your rights and restrictions with respect 67 to this document. Code Components extracted from this document must 68 include Simplified BSD License text as described in Section 4.e of 69 the Trust Legal Provisions and are provided without warranty as 70 described in the Simplified BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 76 3. Communication Scenarios where IEEE 802.11-OCB Links are Used 7 77 4. Aspects introduced by the OCB mode to 802.11 . . . . . . . . 7 78 5. Layering of IPv6 over 802.11-OCB as over Ethernet . . . . . . 11 79 5.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 11 80 5.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 12 81 5.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 13 82 5.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 14 83 5.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 15 84 5.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 15 85 5.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 15 86 5.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 16 87 5.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 17 88 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 89 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 90 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 91 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 92 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 93 10.1. Normative References . . . . . . . . . . . . . . . . . . 19 94 10.2. Informative References . . . . . . . . . . . . . . . . . 22 95 Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 24 96 Appendix B. Changes Needed on a software driver 802.11a to 97 become a 802.11-OCB driver . . . 28 99 Appendix C. Design Considerations . . . . . . . . . . . . . . . 29 100 C.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 29 101 C.2. Reliability Requirements . . . . . . . . . . . . . . . . 30 102 C.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 31 103 C.4. MAC Address Generation . . . . . . . . . . . . . . . . . 31 104 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode . . . . 32 105 Appendix E. Implementation Status . . . . . . . . . . . . . . . 32 106 E.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 33 107 E.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 35 108 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37 110 1. Introduction 112 This document describes the transmission of IPv6 packets on IEEE Std 113 802.11-OCB networks (a.k.a 802.11p) [IEEE-802.11-2016]. This 114 involves the layering of IPv6 networking on top of the IEEE 802.11 115 MAC layer (with an LLC layer). Compared to running IPv6 over the 116 Ethernet MAC layer, there is no modification expected to IEEE Std 117 802.11 MAC and Logical Link sublayers: IPv6 works fine directly over 118 802.11-OCB too (with an LLC layer). 120 The term "802.11p" is an earlier definition. The behaviour of 121 "802.11p" networks is rolled in the document IEEE Std 802.11-2016. 122 In that document the term 802.11p disappears. Instead, each 802.11p 123 feature is conditioned by the Management Information Base (MIB) 124 attribute "OCBActivated". Whenever OCBActivated is set to true the 125 IEEE Std 802.11 OCB state is activated. For example, an 802.11 126 STAtion operating outside the context of a basic service set has the 127 OCBActivated flag set. Such a station, when it has the flag set, 128 uses a BSS identifier equal to ff:ff:ff:ff:ff:ff. 130 The IPv6 network layer operates on 802.11-OCB in the same manner as 131 it operates on 802.11 WiFi, with a few particular exceptions. The 132 IPv6 network layer operates on WiFi by involving an Ethernet 133 Adaptation Layer; this Ethernet Adaptation Layer maps 802.11 headers 134 to Ethernet II headers. The operation of IP on Ethernet is described 135 in [RFC1042], [RFC2464] and [I-D.hinden-6man-rfc2464bis]. The 136 situation of IPv6 networking layer on Ethernet Adaptation Layer is 137 illustrated below: 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 140 | IPv6 | 141 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 142 | Ethernet Adaptation Layer | 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | 802.11 WiFi MAC | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | 802.11 WiFi PHY | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 (in the above figure, a WiFi profile is represented; this is used 150 also for OCB profile.) 152 A more theoretical and detailed view of layer stacking, and 153 interfaces between the IP layer and 802.11-OCB layers, is illustrated 154 below. The IP layer operates on top of the EtherType Protocol 155 Discrimination (EPD); this Discrimination layer is described in IEEE 156 Std 802.3-2012; the interface between IPv6 and EPD is the LLC_SAP 157 (Link Layer Control Service Accesss Point). 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | IPv6 | 161 +-+-+-+-+-+-{ }+-+-+-+-+-+-+-+ 162 { LLC_SAP } 802.11-OCB 163 +-+-+-+-+-+-{ }+-+-+-+-+-+-+-+ Boundary 164 | EPD | | | 165 | | MLME | | 166 +-+-+-{ MAC_SAP }+-+-+-| MLME_SAP | 167 | MAC Sublayer | | | 802.11-OCB 168 | and ch. coord. | | SME | Services 169 +-+-+-{ PHY_SAP }+-+-+-+-+-+-+-| | 170 | | PLME | | 171 | PHY Layer | PLME_SAP | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 In addition to the description of interface between IP and MAC using 175 "Ethernet Adaptation Layer" and "Ethernet Protocol Discrimination 176 (EPD)" it is worth mentioning that SNAP [RFC1042] is used to carry 177 the IPv6 Ethertype. 179 However, there may be some deployment considerations helping optimize 180 the performances of running IPv6 over 802.11-OCB (e.g. in the case of 181 handovers between 802.11-OCB-enabled access routers, or the 182 consideration of using the IP security architecture [RFC4301]). 184 There are currently no specifications for handover between OCB links 185 since these are currently specified as LLC-1 links (i.e. 186 connectionless). Any handovers must be performed above the Data Link 187 Layer. To realize handovers between OCB links there is a need of 188 specific indicators to assist in the handover process. The 189 indicators may be IP Router Advertisements, or 802.11-OCB's Time 190 Advertisements, or application-layer data. However, this document 191 does not describe handover behaviour. 193 The OCB operation is stripped off of all existing 802.11 link-layer 194 security mechanisms. There is no encryption applied below the 195 network layer running on 802.11-OCB. At application layer, the IEEE 196 1609.2 document [IEEE-1609.2] does provide security services for 197 certain applications to use; application-layer mechanisms are out-of- 198 scope of this document. On another hand, a security mechanism 199 provided at networking layer, such as IPsec [RFC4301], may provide 200 data security protection to a wider range of applications. See the 201 section Security Considerations of this document, Section 6 203 We briefly introduce the vehicular communication scenarios where IEEE 204 802.11-OCB links are used. This is followed by a description of 205 differences in specification terms, between 802.11-OCB and 206 802.11a/b/g/n - we answer the question of what are the aspects 207 introduced by OCB mode to 802.11; the same aspects, but expressed in 208 terms of requirements to implementation, are listed in Appendix B.) 210 The document then concentrates on the parameters of layering IP over 211 802.11-OCB as over Ethernet: value of MTU, the Frame Format which 212 includes a description of an Ethernet Adaptation Layer, the forming 213 of Link-Local Addresses the rules for forming Interface Identifiers 214 for Stateless Autoconfiguration, the mechanisms for Address Mapping. 215 These are precisely the same as IPv6 over Ethernet [RFC2464]. A 216 reference is made to ad-hoc networking characteristics of the subnet 217 structure in OCB mode. 219 As an example, these characteristics of layering IPv6 straight over 220 LLC over 802.11-OCB MAC are illustrated by dissecting an IPv6 packet 221 captured over a 802.11-OCB link; this is described in the section 222 Appendix E. 224 In the published literature, many documents describe aspects related 225 to running IPv6 over 802.11-OCB: 226 [I-D.jeong-ipwave-vehicular-networking-survey]. 228 2. Terminology 230 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 231 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 232 document are to be interpreted as described in RFC 2119 [RFC2119]. 234 OBRU (On-Board Router Unit): an OBRU is almost always situated in a 235 vehicle; it is a computer with at least two IP interfaces; at least 236 one IP interface runs in OCB mode of 802.11. It MAY be an IP Router. 238 RSRU (Road-Side Router Unit): an RSRU is almost always situated in a 239 box fixed along the road. An RSRU has at least two distinct IP- 240 enabled interfaces; at least one interface is operated in mode OCB of 241 IEEE 802.11 and is IP-enabled. An RSRU is similar to a Wireless 242 Termination Point (WTP), as defined in [RFC5415], or an Access Point 243 (AP), as defined in IEEE documents, or an Access Network Router (ANR) 244 defined in [RFC3753], with one key particularity: the wireless PHY/ 245 MAC layer of at least one of its IP-enabled interfaces is configured 246 to operate in 802.11-OCB mode. The RSRU communicates with the On 247 board Unit (OBRU) in the vehicle over 802.11 wireless link operating 248 in OCB mode. An RSRU MAY be connected to the Internet, and MAY be an 249 IP Router. When it is connected to the Internet, the term V2I 250 (Vehicle to Internet) is relevant. 252 RSU (Road-Side Unit): an RSU operates in 802.11-OCB mode. A RSU 253 broadcasts data to OBUs or exchanges data with OBUs in its 254 communications zone. An RSU may provides channel assignments and 255 operating instructions to OBUs in its communications zone, when 256 required. The basic functional blocks of an RSU are: internal 257 computer processing, permanent storage capability, an integrated GPS 258 receiver for positioning and timing and an interface that supports 259 both IPv4 and IPv6 connectivity, compliant with 802.3at. An OCB 260 interface of an RSU MAY be IP-enabled simultaneously to being WAVE- 261 enabled or GeoNetworking-enabled (MAY support simultaneously 262 EtherTypes 0x86DD for IPv6 _and_ 0x88DC for WAVE and 0x8947 for 263 GeoNetworking). 265 OCB (outside the context of a basic service set - BSS): A mode of 266 operation in which a STA is not a member of a BSS and does not 267 utilize IEEE Std 802.11 authentication, association, or data 268 confidentiality. 270 802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB 271 attribute dot11OCBActivited is true. The OCB mode requires 272 transmission of QoS data frames (IEEE Std 802.11e), half-clocked 273 operation (IEEE Std 802.11j), and use of 5.9 GHz frequency band. 275 3. Communication Scenarios where IEEE 802.11-OCB Links are Used 277 The IEEE 802.11-OCB Networks are used for vehicular communications, 278 as 'Wireless Access in Vehicular Environments'. The IP communication 279 scenarios for these environments have been described in several 280 documents, among which we refer the reader to one recently updated 281 [I-D.petrescu-its-scenarios-reqs], about scenarios and requirements 282 for IP in Intelligent Transportation Systems. 284 The link model is the following: STA --- 802.11-OCB --- STA. In 285 vehicular networks, STAs can be RSRUs and/or OBRUs. While 802.11-OCB 286 is clearly specified, and the use of IPv6 over such link is not 287 radically new, the operating environment (vehicular networks) brings 288 in new perspectives. 290 The 802.11-OCB links form and terminate; nodes connected to these 291 links peer, and discover each other; the nodes are mobile. However, 292 the precise description of how links discover each other, peer and 293 manage mobility is not given in this document. 295 4. Aspects introduced by the OCB mode to 802.11 297 In the IEEE 802.11-OCB mode, all nodes in the wireless range can 298 directly communicate with each other without involving authentication 299 or association procedures. At link layer, it is necessary to set a 300 same channel number (or frequency) on two stations that need to 301 communicate with each other. Stations STA1 and STA2 can exchange IP 302 packets if they are set on the same channel. At IP layer, they then 303 discover each other by using the IPv6 Neighbor Discovery protocol. 305 Briefly, the IEEE 802.11-OCB mode has the following properties: 307 o The use by each node of a 'wildcard' BSSID (i.e., each bit of the 308 BSSID is set to 1) 310 o No IEEE 802.11 Beacon frames are transmitted 312 o No authentication is required in order to be able to communicate 314 o No association is needed in order to be able to communicate 316 o No encryption is provided in order to be able to communicate 318 o Flag dot11OCBActivated is set to true 320 All the nodes in the radio communication range (OBRU and RSRU) 321 receive all the messages transmitted (OBRU and RSRU) within the radio 322 communications range. The eventual conflict(s) are resolved by the 323 MAC CDMA function. 325 The following message exchange diagram illustrates a comparison 326 between traditional 802.11 and 802.11 in OCB mode. The 'Data' 327 messages can be IP packets such as HTTP or others. Other 802.11 328 management and control frames (non IP) may be transmitted, as 329 specified in the 802.11 standard. For information, the names of 330 these messages as currently specified by the 802.11 standard are 331 listed in Appendix D. 333 STA AP STA1 STA2 334 | | | | 335 |<------ Beacon -------| |<------ Data -------->| 336 | | | | 337 |---- Probe Req. ----->| |<------ Data -------->| 338 |<--- Probe Res. ------| | | 339 | | |<------ Data -------->| 340 |---- Auth Req. ------>| | | 341 |<--- Auth Res. -------| |<------ Data -------->| 342 | | | | 343 |---- Asso Req. ------>| |<------ Data -------->| 344 |<--- Asso Res. -------| | | 345 | | |<------ Data -------->| 346 |<------ Data -------->| | | 347 |<------ Data -------->| |<------ Data -------->| 349 (a) 802.11 Infrastructure mode (b) 802.11-OCB mode 351 The interface 802.11-OCB was specified in IEEE Std 802.11p (TM) -2010 352 [IEEE-802.11p-2010] as an amendment to IEEE Std 802.11 (TM) -2007, 353 titled "Amendment 6: Wireless Access in Vehicular Environments". 354 Since then, this amendment has been included in IEEE 802.11(TM) -2012 355 and -2016 [IEEE-802.11-2016]. 357 In document 802.11-2016, anything qualified specifically as 358 "OCBActivated", or "outside the context of a basic service" set to be 359 true, then it is actually referring to OCB aspects introduced to 360 802.11. 362 In order to delineate the aspects introduced by 802.11-OCB to 802.11, 363 we refer to the earlier [IEEE-802.11p-2010]. The amendment is 364 concerned with vehicular communications, where the wireless link is 365 similar to that of Wireless LAN (using a PHY layer specified by 366 802.11a/b/g/n), but which needs to cope with the high mobility factor 367 inherent in scenarios of communications between moving vehicles, and 368 between vehicles and fixed infrastructure deployed along roads. 369 While 'p' is a letter just like 'a, b, g' and 'n' are, 'p' is 370 concerned more with MAC modifications, and a little with PHY 371 modifications; the others are mainly about PHY modifications. It is 372 possible in practice to combine a 'p' MAC with an 'a' PHY by 373 operating outside the context of a BSS with OFDM at 5.4GHz and 374 5.9GHz. 376 The 802.11-OCB links are specified to be compatible as much as 377 possible with the behaviour of 802.11a/b/g/n and future generation 378 IEEE WLAN links. From the IP perspective, an 802.11-OCB MAC layer 379 offers practically the same interface to IP as the WiFi and Ethernet 380 layers do (802.11a/b/g/n and 802.3). A packet sent by an OBRU may be 381 received by one or multiple RSRUs. The link-layer resolution is 382 performed by using the IPv6 Neighbor Discovery protocol. 384 To support this similarity statement (IPv6 is layered on top of LLC 385 on top of 802.11-OCB, in the same way that IPv6 is layered on top of 386 LLC on top of 802.11a/b/g/n (for WLAN) or layered on top of LLC on 387 top of 802.3 (for Ethernet)) it is useful to analyze the differences 388 between 802.11-OCB and 802.11 specifications. During this analysis, 389 we note that whereas 802.11-OCB lists relatively complex and numerous 390 changes to the MAC layer (and very little to the PHY layer), there 391 are only a few characteristics which may be important for an 392 implementation transmitting IPv6 packets on 802.11-OCB links. 394 The most important 802.11-OCB point which influences the IPv6 395 functioning is the OCB characteristic; an additional, less direct 396 influence, is the maximum bandwidth afforded by the PHY modulation/ 397 demodulation methods and channel access specified by 802.11-OCB. The 398 maximum bandwidth theoretically possible in 802.11-OCB is 54 Mbit/s 399 (when using, for example, the following parameters: 20 MHz channel; 400 modulation 64-QAM; codint rate R is 3/4); in practice of IP-over- 401 802.11-OCB a commonly observed figure is 12Mbit/s; this bandwidth 402 allows the operation of a wide range of protocols relying on IPv6. 404 o Operation Outside the Context of a BSS (OCB): the (earlier 405 802.11p) 802.11-OCB links are operated without a Basic Service Set 406 (BSS). This means that the frames IEEE 802.11 Beacon, Association 407 Request/Response, Authentication Request/Response, and similar, 408 are not used. The used identifier of BSS (BSSID) has a 409 hexadecimal value always 0xffffffffffff (48 '1' bits, represented 410 as MAC address ff:ff:ff:ff:ff:ff, or otherwise the 'wildcard' 411 BSSID), as opposed to an arbitrary BSSID value set by 412 administrator (e.g. 'My-Home-AccessPoint'). The OCB operation - 413 namely the lack of beacon-based scanning and lack of 414 authentication - should be taken into account when the Mobile IPv6 415 protocol [RFC6275] and the protocols for IP layer security 417 [RFC4301] are used. The way these protocols adapt to OCB is not 418 described in this document. 420 o Timing Advertisement: is a new message defined in 802.11-OCB, 421 which does not exist in 802.11a/b/g/n. This message is used by 422 stations to inform other stations about the value of time. It is 423 similar to the time as delivered by a GNSS system (Galileo, GPS, 424 ...) or by a cellular system. This message is optional for 425 implementation. 427 o Frequency range: this is a characteristic of the PHY layer, with 428 almost no impact to the interface between MAC and IP. However, it 429 is worth considering that the frequency range is regulated by a 430 regional authority (ARCEP, ETSI, FCC, etc.); as part of the 431 regulation process, specific applications are associated with 432 specific frequency ranges. In the case of 802.11-OCB, the 433 regulator associates a set of frequency ranges, or slots within a 434 band, to the use of applications of vehicular communications, in a 435 band known as "5.9GHz". The 5.9GHz band is different from the 436 2.4GHz and 5GHz bands used by Wireless LAN. However, as with 437 Wireless LAN, the operation of 802.11-OCB in "5.9GHz" bands is 438 exempt from owning a license in EU (in US the 5.9GHz is a licensed 439 band of spectrum; for the fixed infrastructure an explicit FCC 440 autorization is required; for an onboard device a 'licensed-by- 441 rule' concept applies: rule certification conformity is required); 442 however technical conditions are different than those of the bands 443 "2.4GHz" or "5GHz". On one hand, the allowed power levels, and 444 implicitly the maximum allowed distance between vehicles, is of 445 33dBm for 802.11-OCB (in Europe), compared to 20 dBm for Wireless 446 LAN 802.11a/b/g/n; this leads to a maximum distance of 447 approximately 1km, compared to approximately 50m. On the other 448 hand, specific conditions related to congestion avoidance, jamming 449 avoidance, and radar detection are imposed on the use of DSRC (in 450 US) and on the use of frequencies for Intelligent Transportation 451 Systems (in EU), compared to Wireless LAN (802.11a/b/g/n). 453 o Prohibition of IPv6 on some channels relevant for IEEE 802.11-OCB, 454 as opposed to IPv6 not being prohibited on any channel on which 455 802.11a/b/g/n runs: 457 * Some channels are reserved for safety communications; the IPv6 458 packets should not be sent on these channels. 460 * At the time of writing, the prohibition is explicit at higher 461 layer protocols providing services to the application; these 462 higher layer protocols are specified in IEEE 1609 documents, 463 i.e. the "WAVE" stack. 465 * National or regional specifications and regulations specify the 466 use of different channels; these regulations must be followed. 468 o 'Half-rate' encoding: as the frequency range, this parameter is 469 related to PHY, and thus has not much impact on the interface 470 between the IP layer and the MAC layer. 472 o In vehicular communications using 802.11-OCB links, there are 473 strong privacy requirements with respect to addressing. While the 474 802.11-OCB standard does not specify anything in particular with 475 respect to MAC addresses, in these settings there exists a strong 476 need for dynamic change of these addresses (as opposed to the non- 477 vehicular settings - real wall protection - where fixed MAC 478 addresses do not currently pose some privacy risks). This is 479 further described in section Section 6. A relevant function is 480 described in IEEE 1609.3-2016 [IEEE-1609.3], clause 5.5.1 and IEEE 481 1609.4-2016 [IEEE-1609.4], clause 6.7. 483 Other aspects particular to 802.11-OCB, which are also particular to 484 802.11 (e.g. the 'hidden node' operation), may have an influence on 485 the use of transmission of IPv6 packets on 802.11-OCB networks. The 486 OCB subnet structure is described in section Section 5.6. 488 5. Layering of IPv6 over 802.11-OCB as over Ethernet 490 5.1. Maximum Transmission Unit (MTU) 492 The default MTU for IP packets on 802.11-OCB is 1500 octets. It is 493 the same value as IPv6 packets on Ethernet links, as specified in 494 [RFC2464]. This value of the MTU respects the recommendation that 495 every link in the Internet must have a minimum MTU of 1280 octets 496 (stated in [RFC8200], and the recommendations therein, especially 497 with respect to fragmentation). If IPv6 packets of size larger than 498 1500 bytes are sent on an 802.11-OCB interface card then the IP stack 499 will fragment. In case there are IP fragments, the field "Sequence 500 number" of the 802.11 Data header containing the IP fragment field is 501 increased. 503 Non-IP packets such as WAVE Short Message Protocol (WSMP) can be 504 delivered on 802.11-OCB links. Specifications of these packets are 505 out of scope of this document, and do not impose any limit on the MTU 506 size, allowing an arbitrary number of 'containers'. Non-IP packets 507 such as ETSI GeoNetworking packets have an MTU of 1492 bytes. The 508 operation of IPv6 over GeoNetworking is specified at 509 [ETSI-IPv6-GeoNetworking]. 511 5.2. Frame Format 513 IP packets are transmitted over 802.11-OCB as standard Ethernet 514 packets. As with all 802.11 frames, an Ethernet adaptation layer is 515 used with 802.11-OCB as well. This Ethernet Adaptation Layer 516 performing 802.11-to-Ethernet is described in Section 5.2.1. The 517 Ethernet Type code (EtherType) for IPv6 is 0x86DD (hexadecimal 86DD, 518 or otherwise #86DD). 520 The Frame format for transmitting IPv6 on 802.11-OCB networks is the 521 same as transmitting IPv6 on Ethernet networks, and is described in 522 section 3 of [RFC2464]. The frame format for transmitting IPv6 523 packets over Ethernet is illustrated below: 525 0 1 526 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 528 | Destination | 529 +- -+ 530 | Ethernet | 531 +- -+ 532 | Address | 533 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 | Source | 535 +- -+ 536 | Ethernet | 537 +- -+ 538 | Address | 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 540 |1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1| 541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 542 | IPv6 | 543 +- -+ 544 | header | 545 +- -+ 546 | and | 547 +- -+ 548 / payload ... / 549 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 (Each tic mark represents one bit.) 552 Ethernet II Fields: 554 Destination Ethernet Address 555 the MAC destination address. 557 Source Ethernet Address 558 the MAC source address. 560 1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1 561 binary representation of the EtherType value 0x86DD. 563 IPv6 header and payload 564 the IPv6 packet containing IPv6 header and payload. 566 5.2.1. Ethernet Adaptation Layer 568 In general, an 'adaptation' layer is inserted between a MAC layer and 569 the Networking layer. This is used to transform some parameters 570 between their form expected by the IP stack and the form provided by 571 the MAC layer. For example, an 802.15.4 adaptation layer may perform 572 fragmentation and reassembly operations on a MAC whose maximum Packet 573 Data Unit size is smaller than the minimum MTU recognized by the IPv6 574 Networking layer. Other examples involve link-layer address 575 transformation, packet header insertion/removal, and so on. 577 An Ethernet Adaptation Layer makes an 802.11 MAC look to IP 578 Networking layer as a more traditional Ethernet layer. At reception, 579 this layer takes as input the IEEE 802.11 Data Header and the 580 Logical-Link Layer Control Header and produces an Ethernet II Header. 581 At sending, the reverse operation is performed. 583 +--------------------+------------+-------------+---------+-----------+ 584 | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| 585 +--------------------+------------+-------------+---------+-----------+ 586 \ / \ / 587 ----------------------------- -------- 588 ^---------------------------------------------/ 589 | 590 802.11-to-Ethernet Adaptation Layer 591 | 592 v 593 +---------------------+-------------+---------+ 594 | Ethernet II Header | IPv6 Header | Payload | 595 +---------------------+-------------+---------+ 597 The Receiver and Transmitter Address fields in the 802.11 Data Header 598 contain the same values as the Destination and the Source Address 599 fields in the Ethernet II Header, respectively. The value of the 600 Type field in the LLC Header is the same as the value of the Type 601 field in the Ethernet II Header. 603 The ".11 Trailer" contains solely a 4-byte Frame Check Sequence. 605 The Ethernet Adaptation Layer performs operations in relation to IP 606 fragmentation and MTU. One of these operations is briefly described 607 in section Section 5.1. 609 In OCB mode, IPv6 packets can be transmitted either as "IEEE 802.11 610 Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in 611 the figure below. Some commercial OCB products use 802.11 Data, and 612 others 802.11 QoS data. In the future, both could be used. 614 +--------------------+-------------+-------------+---------+-----------+ 615 | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| 616 +--------------------+-------------+-------------+---------+-----------+ 618 or 620 +--------------------+-------------+-------------+---------+-----------+ 621 | 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload |.11 Trailer| 622 +--------------------+-------------+-------------+---------+-----------+ 624 The distinction between the two formats is given by the value of the 625 field "Type/Subtype". The value of the field "Type/Subtype" in the 626 802.11 Data header is 0x0020. The value of the field "Type/Subtype" 627 in the 802.11 QoS header is 0x0028. 629 The mapping between qos-related fields in the IPv6 header (e.g. 630 "Traffic Class", "Flow label") and fields in the "802.11 QoS Data 631 Header" (e.g. "QoS Control") are not specified in this document. 632 Guidance for a potential mapping is provided in 633 [I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB 634 mode. 636 5.3. Link-Local Addresses 638 The link-local address of an 802.11-OCB interface is formed in the 639 same manner as on an Ethernet interface. This manner is described in 640 section 5 of [RFC2464]. Additionally, if stable identifiers are 641 needed, it is recommended to follow the Recommendation on Stable IPv6 642 Interface Identifiers [RFC8064]. Additionally, if semantically 643 opaque Interface Identifiers are needed, a potential method for 644 generating semantically opaque Interface Identifiers with IPv6 645 Stateless Address Autoconfiguration is given in [RFC7217]. 647 5.4. Address Mapping 649 For unicast as for multicast, there is no change from the unicast and 650 multicast address mapping format of Ethernet interfaces, as defined 651 by sections 6 and 7 of [RFC2464]. 653 5.4.1. Address Mapping -- Unicast 655 The procedure for mapping IPv6 unicast addresses into Ethernet link- 656 layer addresses is described in [RFC4861]. The Source/Target Link- 657 layer Address option has the following form when the link-layer is 658 Ethernet. 660 0 1 661 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 662 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 663 | Type | Length | 664 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 665 | | 666 +- Ethernet -+ 667 | | 668 +- Address -+ 669 | | 670 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 672 Option fields: 674 Type 675 1 for Source Link-layer address. 676 2 for Target Link-layer address. 678 Length 679 1 (in units of 8 octets). 681 Ethernet Address 682 The 48 bit Ethernet IEEE 802 address, in canonical bit order. 684 5.4.2. Address Mapping -- Multicast 686 IPv6 protocols often make use of IPv6 multicast addresses in the 687 destination field of IPv6 headers. For example, an ICMPv6 link- 688 scoped Neighbor Advertisement is sent to the IPv6 address ff02::1 689 denoted "all-nodes" address. When transmitting these packets on 690 802.11-OCB links it is necessary to map the IPv6 address to a MAC 691 address. 693 The same mapping requirement applies to the link-scoped multicast 694 addresses of other IPv6 protocols as well. In DHCPv6, the 695 "All_DHCP_Servers" IPv6 multicast address ff02::1:2, and in OSPF the 696 "All_SPF_Routers" IPv6 multicast address ff02::5, need to be mapped 697 on a multicast MAC address. 699 An IPv6 packet with a multicast destination address DST, consisting 700 of the sixteen octets DST[1] through DST[16], is transmitted to the 701 IEEE 802.11-OCB MAC multicast address whose first two octets are the 702 value 0x3333 and whose last four octets are the last four octets of 703 DST. 705 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 706 |0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1| 707 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 708 | DST[13] | DST[14] | 709 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 710 | DST[15] | DST[16] | 711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 713 A Group ID named TBD, of length 112bits is requested to IANA; this 714 Group ID signifies "All 80211OCB Interfaces Address". Only the least 715 32 significant bits of this "All 80211OCB Interfaces Address" will be 716 mapped to and from a MAC multicast address. 718 Transmitting IPv6 packets to multicast destinations over 802.11 links 719 proved to have some performance issues 720 [I-D.perkins-intarea-multicast-ieee802]. These issues may be 721 exacerbated in OCB mode. Solutions for these problems should 722 consider the OCB mode of operation. 724 5.5. Stateless Autoconfiguration 726 The Interface Identifier for an 802.11-OCB interface is formed using 727 the same rules as the Interface Identifier for an Ethernet interface; 728 this is described in section 4 of [RFC2464]. No changes are needed, 729 but some care must be taken when considering the use of the SLAAC 730 procedure. 732 The bits in the the interface identifier have no generic meaning and 733 the identifier should be treated as an opaque value. The bits 734 'Universal' and 'Group' in the identifier of an 802.11-OCB interface 735 are significant, as this is an IEEE link-layer address. The details 736 of this significance are described in [RFC7136]. 738 As with all Ethernet and 802.11 interface identifiers ([RFC7721]), 739 the identifier of an 802.11-OCB interface may involve privacy, MAC 740 address spoofing and IP address hijacking risks. A vehicle embarking 741 an On-Board Unit whose egress interface is 802.11-OCB may expose 742 itself to eavesdropping and subsequent correlation of data; this may 743 reveal data considered private by the vehicle owner; there is a risk 744 of being tracked; see the privacy considerations described in 745 Appendix C. 747 If stable Interface Identifiers are needed in order to form IPv6 748 addresses on 802.11-OCB links, it is recommended to follow the 749 recommendation in [RFC8064]. Additionally, if semantically opaque 750 Interface Identifiers are needed, a potential method for generating 751 semantically opaque Interface Identifiers with IPv6 Stateless Address 752 Autoconfiguration is given in [RFC7217]. 754 5.6. Subnet Structure 756 A subnet is formed by the external 802.11-OCB interfaces of vehicles 757 that are in close range (not their on-board interfaces). This 758 ephemeral subnet structure is strongly influenced by the mobility of 759 vehicles: the 802.11 hidden node effects appear. On another hand, 760 the structure of the internal subnets in each car is relatively 761 stable. 763 For routing purposes, a prefix exchange mechanism could be needed 764 between neighboring vehicles. 766 The 802.11 networks in OCB mode may be considered as 'ad-hoc' 767 networks. The addressing model for such networks is described in 768 [RFC5889]. 770 An addressing model involves several types of addresses, like 771 Globally-unique Addresses (GUA), Link-Local Addresses (LL) and Unique 772 Local Addresses (ULA). The subnet structure in 'ad-hoc' networks may 773 have characteristics that lead to difficulty of using GUAs derived 774 from a received prefix, but the LL addresses may be easier to use 775 since the prefix is constant. 777 6. Security Considerations 779 Any security mechanism at the IP layer or above that may be carried 780 out for the general case of IPv6 may also be carried out for IPv6 781 operating over 802.11-OCB. 783 802.11-OCB does not provide any cryptographic protection, because it 784 operates outside the context of a BSS (no Association Request/ 785 Response, no Challenge messages). Any attacker can therefore just 786 sit in the near range of vehicles, sniff the network (just set the 787 interface card's frequency to the proper range) and perform attacks 788 without needing to physically break any wall. Such a link is less 789 protected than commonly used links (wired link or protected 802.11). 791 The potential attack vectors are: MAC address spoofing, IP address 792 and session hijacking and privacy violation. 794 Within the IPsec Security Architecture [RFC4301], the IPsec AH and 795 ESP headers [RFC4302] and [RFC4303] respectively, its multicast 796 extensions [RFC5374], HTTPS [RFC2818] and SeND [RFC3971] protocols 797 can be used to protect communications. Further, the assistance of 798 proper Public Key Infrastructure (PKI) protocols [RFC4210] is 799 necessary to establish credentials. More IETF protocols are 800 available in the toolbox of the IP security protocol designer. 801 Certain ETSI protocols related to security protocols in Intelligent 802 Transportation Systems are described in [ETSI-sec-archi]. 804 As with all Ethernet and 802.11 interface identifiers, there may 805 exist privacy risks in the use of 802.11-OCB interface identifiers. 806 Moreover, in outdoors vehicular settings, the privacy risks are more 807 important than in indoors settings. New risks are induced by the 808 possibility of attacker sniffers deployed along routes which listen 809 for IP packets of vehicles passing by. For this reason, in the 810 802.11-OCB deployments, there is a strong necessity to use protection 811 tools such as dynamically changing MAC addresses. This may help 812 mitigate privacy risks to a certain level. On another hand, it may 813 have an impact in the way typical IPv6 address auto-configuration is 814 performed for vehicles (SLAAC would rely on MAC addresses amd would 815 hence dynamically change the affected IP address), in the way the 816 IPv6 Privacy addresses were used, and other effects. 818 7. IANA Considerations 820 A Group ID named TBD, of length 112bits is requested to IANA; this 821 Group ID signifies "All 80211OCB Interfaces Address". 823 8. Contributors 825 Romain Kuntz contributed extensively about IPv6 handovers between 826 links running outside the context of a BSS (802.11-OCB links). 828 Tim Leinmueller contributed the idea of the use of IPv6 over 829 802.11-OCB for distribution of certificates. 831 Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey 832 Voronov provided significant feedback on the experience of using IP 833 messages over 802.11-OCB in initial trials. 835 Michelle Wetterwald contributed extensively the MTU discussion, 836 offered the ETSI ITS perspective, and reviewed other parts of the 837 document. 839 9. Acknowledgements 841 The authors would like to thank Witold Klaudel, Ryuji Wakikawa, 842 Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan 843 Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray 844 Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan, 845 Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne, 846 Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, Erik Nordmark, 847 Bob Moskowitz, Andrew (Dryden?), Georg Mayer, Dorothy Stanley, Sandra 848 Cespedes, Mariano Falcitelli, Sri Gundavelli and William Whyte. 849 Their valuable comments clarified particular issues and generally 850 helped to improve the document. 852 Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB 853 drivers for linux and described how. 855 For the multicast discussion, the authors would like to thank Owen 856 DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and 857 participants to discussions in network working groups. 859 The authours would like to thank participants to the Birds-of- 860 a-Feather "Intelligent Transportation Systems" meetings held at IETF 861 in 2016. 863 10. References 865 10.1. Normative References 867 [I-D.ietf-tsvwg-ieee-802-11] 868 Szigeti, T., Henry, J., and F. Baker, "Diffserv to IEEE 869 802.11 Mapping", draft-ietf-tsvwg-ieee-802-11-08 (work in 870 progress), September 2017. 872 [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission 873 of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, 874 DOI 10.17487/RFC1042, February 1988, 875 . 877 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 878 Requirement Levels", BCP 14, RFC 2119, 879 DOI 10.17487/RFC2119, March 1997, 880 . 882 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 883 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 884 . 886 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 887 DOI 10.17487/RFC2818, May 2000, 888 . 890 [RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related 891 Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004, 892 . 894 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 895 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 896 RFC 3963, DOI 10.17487/RFC3963, January 2005, 897 . 899 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 900 "SEcure Neighbor Discovery (SEND)", RFC 3971, 901 DOI 10.17487/RFC3971, March 2005, 902 . 904 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 905 "Randomness Requirements for Security", BCP 106, RFC 4086, 906 DOI 10.17487/RFC4086, June 2005, 907 . 909 [RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen, 910 "Internet X.509 Public Key Infrastructure Certificate 911 Management Protocol (CMP)", RFC 4210, 912 DOI 10.17487/RFC4210, September 2005, 913 . 915 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 916 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 917 December 2005, . 919 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 920 DOI 10.17487/RFC4302, December 2005, 921 . 923 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 924 RFC 4303, DOI 10.17487/RFC4303, December 2005, 925 . 927 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 928 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 929 . 931 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 932 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 933 DOI 10.17487/RFC4861, September 2007, 934 . 936 [RFC5374] Weis, B., Gross, G., and D. Ignjatic, "Multicast 937 Extensions to the Security Architecture for the Internet 938 Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008, 939 . 941 [RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, 942 Ed., "Control And Provisioning of Wireless Access Points 943 (CAPWAP) Protocol Specification", RFC 5415, 944 DOI 10.17487/RFC5415, March 2009, 945 . 947 [RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing 948 Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889, 949 September 2010, . 951 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 952 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 953 2011, . 955 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 956 Bormann, "Neighbor Discovery Optimization for IPv6 over 957 Low-Power Wireless Personal Area Networks (6LoWPANs)", 958 RFC 6775, DOI 10.17487/RFC6775, November 2012, 959 . 961 [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 962 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, 963 February 2014, . 965 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 966 Interface Identifiers with IPv6 Stateless Address 967 Autoconfiguration (SLAAC)", RFC 7217, 968 DOI 10.17487/RFC7217, April 2014, 969 . 971 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 972 Considerations for IPv6 Address Generation Mechanisms", 973 RFC 7721, DOI 10.17487/RFC7721, March 2016, 974 . 976 [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, 977 "Recommendation on Stable IPv6 Interface Identifiers", 978 RFC 8064, DOI 10.17487/RFC8064, February 2017, 979 . 981 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 982 (IPv6) Specification", STD 86, RFC 8200, 983 DOI 10.17487/RFC8200, July 2017, 984 . 986 10.2. Informative References 988 [ETSI-IPv6-GeoNetworking] 989 "ETSI EN 302 636-6-1 v1.2.1 (2014-05), ETSI, European 990 Standard, Intelligent Transportation Systems (ITS); 991 Vehicular Communications; Geonetworking; Part 6: Internet 992 Integration; Sub-part 1: Transmission of IPv6 Packets over 993 Geonetworking Protocols. Downloaded on September 9th, 994 2017, freely available from ETSI website at URL 995 http://www.etsi.org/deliver/ 996 etsi_en/302600_302699/30263601/01.02.01_60/ 997 en_30263601v010201p.pdf". 999 [ETSI-sec-archi] 1000 "ETSI TS 102 940 V1.2.1 (2016-11), ETSI Technical 1001 Specification, Intelligent Transport Systems (ITS); 1002 Security; ITS communications security architecture and 1003 security management, November 2016. Dowloaded on 1004 September 9th, 2017, freely available from ETSI website at 1005 URL http://www.etsi.org/deliver/ 1006 etsi_ts/102900_102999/102940/01.02.01_60/ 1007 ts_102940v010201p.pdf". 1009 [I-D.hinden-6man-rfc2464bis] 1010 Crawford, M. and R. Hinden, "Transmission of IPv6 Packets 1011 over Ethernet Networks", draft-hinden-6man-rfc2464bis-02 1012 (work in progress), March 2017. 1014 [I-D.jeong-ipwave-vehicular-networking-survey] 1015 Jeong, J., Cespedes, S., Benamar, N., Haerri, J., and M. 1016 Wetterwald, "Survey on IP-based Vehicular Networking for 1017 Intelligent Transportation Systems", draft-jeong-ipwave- 1018 vehicular-networking-survey-03 (work in progress), June 1019 2017. 1021 [I-D.perkins-intarea-multicast-ieee802] 1022 Perkins, C., Stanley, D., Kumari, W., and J. Zuniga, 1023 "Multicast Considerations over IEEE 802 Wireless Media", 1024 draft-perkins-intarea-multicast-ieee802-03 (work in 1025 progress), July 2017. 1027 [I-D.petrescu-its-scenarios-reqs] 1028 Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel, 1029 "Scenarios and Requirements for IP in Intelligent 1030 Transportation Systems", draft-petrescu-its-scenarios- 1031 reqs-03 (work in progress), October 2013. 1033 [IEEE-1609.2] 1034 "IEEE SA - 1609.2-2016 - IEEE Standard for Wireless Access 1035 in Vehicular Environments (WAVE) -- Security Services for 1036 Applications and Management Messages. Example URL 1037 http://ieeexplore.ieee.org/document/7426684/ accessed on 1038 August 17th, 2017.". 1040 [IEEE-1609.3] 1041 "IEEE SA - 1609.3-2016 - IEEE Standard for Wireless Access 1042 in Vehicular Environments (WAVE) -- Networking Services. 1043 Example URL http://ieeexplore.ieee.org/document/7458115/ 1044 accessed on August 17th, 2017.". 1046 [IEEE-1609.4] 1047 "IEEE SA - 1609.4-2016 - IEEE Standard for Wireless Access 1048 in Vehicular Environments (WAVE) -- Multi-Channel 1049 Operation. Example URL 1050 http://ieeexplore.ieee.org/document/7435228/ accessed on 1051 August 17th, 2017.". 1053 [IEEE-802.11-2016] 1054 "IEEE Standard 802.11-2016 - IEEE Standard for Information 1055 Technology - Telecommunications and information exchange 1056 between systems Local and metropolitan area networks - 1057 Specific requirements - Part 11: Wireless LAN Medium 1058 Access Control (MAC) and Physical Layer (PHY) 1059 Specifications. Status - Active Standard. Description 1060 retrieved freely on September 12th, 2017, at URL 1061 https://standards.ieee.org/findstds/ 1062 standard/802.11-2016.html". 1064 [IEEE-802.11p-2010] 1065 "IEEE Std 802.11p (TM)-2010, IEEE Standard for Information 1066 Technology - Telecommunications and information exchange 1067 between systems - Local and metropolitan area networks - 1068 Specific requirements, Part 11: Wireless LAN Medium Access 1069 Control (MAC) and Physical Layer (PHY) Specifications, 1070 Amendment 6: Wireless Access in Vehicular Environments; 1071 document freely available at URL 1072 http://standards.ieee.org/getieee802/ 1073 download/802.11p-2010.pdf retrieved on September 20th, 1074 2013.". 1076 Appendix A. ChangeLog 1078 The changes are listed in reverse chronological order, most recent 1079 changes appearing at the top of the list. 1081 From draft-ietf-ipwave-ipv6-over-80211ocb-06 to draft-ietf-ipwave- 1082 ipv6-over-80211ocb-07 1084 o Added new terms: OBRU and RSRU ('R' for Router). Refined the 1085 existing terms RSU and OBU, which are no longer used throughout 1086 the document. 1088 o Improved definition of term "802.11-OCB". 1090 o Clarified that OCB does not "strip" security, but that the 1091 operation in OCB mode is "stripped off of all .11 security". 1093 o Clarified that theoretical OCB bandwidth speed is 54mbits, but 1094 that a commonly observed bandwidth in IP-over-OCB is 12mbit/s. 1096 o Corrected typographical errors, and improved some phrasing. 1098 From draft-ietf-ipwave-ipv6-over-80211ocb-05 to draft-ietf-ipwave- 1099 ipv6-over-80211ocb-06 1101 o Updated references of 802.11-OCB document from -2012 to the IEEE 1102 802.11-2016. 1104 o In the LL address section, and in SLAAC section, added references 1105 to 7217 opaque IIDs and 8064 stable IIDs. 1107 From draft-ietf-ipwave-ipv6-over-80211ocb-04 to draft-ietf-ipwave- 1108 ipv6-over-80211ocb-05 1110 o Lengthened the title and cleanded the abstract. 1112 o Added text suggesting LLs may be easy to use on OCB, rather than 1113 GUAs based on received prefix. 1115 o Added the risks of spoofing and hijacking. 1117 o Removed the text speculation on adoption of the TSA message. 1119 o Clarified that the ND protocol is used. 1121 o Clarified what it means "No association needed". 1123 o Added some text about how two STAs discover each other. 1125 o Added mention of external (OCB) and internal network (stable), in 1126 the subnet structure section. 1128 o Added phrase explaining that both .11 Data and .11 QoS Data 1129 headers are currently being used, and may be used in the future. 1131 o Moved the packet capture example into an Appendix Implementation 1132 Status. 1134 o Suggested moving the reliability requirements appendix out into 1135 another document. 1137 o Added a IANA Consiserations section, with content, requesting for 1138 a new multicast group "all OCB interfaces". 1140 o Added new OBU term, improved the RSU term definition, removed the 1141 ETTC term, replaced more occurences of 802.11p, 802.11 OCB with 1142 802.11-OCB. 1144 o References: 1146 * Added an informational reference to ETSI's IPv6-over- 1147 GeoNetworking. 1149 * Added more references to IETF and ETSI security protocols. 1151 * Updated some references from I-D to RFC, and from old RFC to 1152 new RFC numbers. 1154 * Added reference to multicast extensions to IPsec architecture 1155 RFC. 1157 * Added a reference to 2464-bis. 1159 * Removed FCC informative references, because not used. 1161 o Updated the affiliation of one author. 1163 o Reformulation of some phrases for better readability, and 1164 correction of typographical errors. 1166 From draft-ietf-ipwave-ipv6-over-80211ocb-03 to draft-ietf-ipwave- 1167 ipv6-over-80211ocb-04 1169 o Removed a few informative references pointing to Dx draft IEEE 1170 1609 documents. 1172 o Removed outdated informative references to ETSI documents. 1174 o Added citations to IEEE 1609.2, .3 and .4-2016. 1176 o Minor textual issues. 1178 From draft-ietf-ipwave-ipv6-over-80211ocb-02 to draft-ietf-ipwave- 1179 ipv6-over-80211ocb-03 1181 o Keep the previous text on multiple addresses, so remove talk about 1182 MIP6, NEMOv6 and MCoA. 1184 o Clarified that a 'Beacon' is an IEEE 802.11 frame Beacon. 1186 o Clarified the figure showing Infrastructure mode and OCB mode side 1187 by side. 1189 o Added a reference to the IP Security Architecture RFC. 1191 o Detailed the IPv6-per-channel prohibition paragraph which reflects 1192 the discussion at the last IETF IPWAVE WG meeting. 1194 o Added section "Address Mapping -- Unicast". 1196 o Added the ".11 Trailer" to pictures of 802.11 frames. 1198 o Added text about SNAP carrying the Ethertype. 1200 o New RSU definition allowing for it be both a Router and not 1201 necessarily a Router some times. 1203 o Minor textual issues. 1205 From draft-ietf-ipwave-ipv6-over-80211ocb-01 to draft-ietf-ipwave- 1206 ipv6-over-80211ocb-02 1207 o Replaced almost all occurences of 802.11p with 802.11-OCB, leaving 1208 only when explanation of evolution was necessary. 1210 o Shortened by removing parameter details from a paragraph in the 1211 Introduction. 1213 o Moved a reference from Normative to Informative. 1215 o Added text in intro clarifying there is no handover spec at IEEE, 1216 and that 1609.2 does provide security services. 1218 o Named the contents the fields of the EthernetII header (including 1219 the Ethertype bitstring). 1221 o Improved relationship between two paragraphs describing the 1222 increase of the Sequence Number in 802.11 header upon IP 1223 fragmentation. 1225 o Added brief clarification of "tracking". 1227 From draft-ietf-ipwave-ipv6-over-80211ocb-00 to draft-ietf-ipwave- 1228 ipv6-over-80211ocb-01 1230 o Introduced message exchange diagram illustrating differences 1231 between 802.11 and 802.11 in OCB mode. 1233 o Introduced an appendix listing for information the set of 802.11 1234 messages that may be transmitted in OCB mode. 1236 o Removed appendix sections "Privacy Requirements", "Authentication 1237 Requirements" and "Security Certificate Generation". 1239 o Removed appendix section "Non IP Communications". 1241 o Introductory phrase in the Security Considerations section. 1243 o Improved the definition of "OCB". 1245 o Introduced theoretical stacked layers about IPv6 and IEEE layers 1246 including EPD. 1248 o Removed the appendix describing the details of prohibiting IPv6 on 1249 certain channels relevant to 802.11-OCB. 1251 o Added a brief reference in the privacy text about a precise clause 1252 in IEEE 1609.3 and .4. 1254 o Clarified the definition of a Road Side Unit. 1256 o Removed the discussion about security of WSA (because is non-IP). 1258 o Removed mentioning of the GeoNetworking discussion. 1260 o Moved references to scientific articles to a separate 'overview' 1261 draft, and referred to it. 1263 Appendix B. Changes Needed on a software driver 802.11a to become a 1264 802.11-OCB driver 1266 The 802.11p amendment modifies both the 802.11 stack's physical and 1267 MAC layers but all the induced modifications can be quite easily 1268 obtained by modifying an existing 802.11a ad-hoc stack. 1270 Conditions for a 802.11a hardware to be 802.11-OCB compliant: 1272 o The PHY entity shall be an orthogonal frequency division 1273 multiplexing (OFDM) system. It must support the frequency bands 1274 on which the regulator recommends the use of ITS communications, 1275 for example using IEEE 802.11-OCB layer, in France: 5875MHz to 1276 5925MHz. 1278 o The OFDM system must provide a "half-clocked" operation using 10 1279 MHz channel spacings. 1281 o The chip transmit spectrum mask must be compliant to the "Transmit 1282 spectrum mask" from the IEEE 802.11p amendment (but experimental 1283 environments tolerate otherwise). 1285 o The chip should be able to transmit up to 44.8 dBm when used by 1286 the US government in the United States, and up to 33 dBm in 1287 Europe; other regional conditions apply. 1289 Changes needed on the network stack in OCB mode: 1291 o Physical layer: 1293 * The chip must use the Orthogonal Frequency Multiple Access 1294 (OFDM) encoding mode. 1296 * The chip must be set in half-mode rate mode (the internal clock 1297 frequency is divided by two). 1299 * The chip must use dedicated channels and should allow the use 1300 of higher emission powers. This may require modifications to 1301 the local computer file that describes regulatory domains 1302 rules, if used by the kernel to enforce local specific 1303 restrictions. Such modifications to the local computer file 1304 must respect the location-specific regulatory rules. 1306 MAC layer: 1308 * All management frames (beacons, join, leave, and others) 1309 emission and reception must be disabled except for frames of 1310 subtype Action and Timing Advertisement (defined below). 1312 * No encryption key or method must be used. 1314 * Packet emission and reception must be performed as in ad-hoc 1315 mode, using the wildcard BSSID (ff:ff:ff:ff:ff:ff). 1317 * The functions related to joining a BSS (Association Request/ 1318 Response) and for authentication (Authentication Request/Reply, 1319 Challenge) are not called. 1321 * The beacon interval is always set to 0 (zero). 1323 * Timing Advertisement frames, defined in the amendment, should 1324 be supported. The upper layer should be able to trigger such 1325 frames emission and to retrieve information contained in 1326 received Timing Advertisements. 1328 Appendix C. Design Considerations 1330 The networks defined by 802.11-OCB are in many ways similar to other 1331 networks of the 802.11 family. In theory, the encapsulation of IPv6 1332 over 802.11-OCB could be very similar to the operation of IPv6 over 1333 other networks of the 802.11 family. However, the high mobility, 1334 strong link asymmetry and very short connection makes the 802.11-OCB 1335 link significantly different from other 802.11 networks. Also, the 1336 automotive applications have specific requirements for reliability, 1337 security and privacy, which further add to the particularity of the 1338 802.11-OCB link. 1340 C.1. Vehicle ID 1342 In automotive networks it is required that each node is represented 1343 uniquely. Accordingly, a vehicle must be identified by at least one 1344 unique identifier. The current specification at ETSI and at IEEE 1345 1609 identifies a vehicle by its MAC address, which is obtained from 1346 the 802.11-OCB Network Interface Card (NIC). 1348 In case multiple 802.11-OCB NICs are present in one car, implicitely 1349 multiple vehicle IDs will be generated. Additionally, some software 1350 generates a random MAC address each time the computer boots; this 1351 constitutes an additional difficulty. 1353 A mechanim to uniquely identify a vehicle irrespectively to the 1354 multiplicity of NICs, or frequent MAC address generation, is 1355 necessary. 1357 C.2. Reliability Requirements 1359 This section may need to be moved out into a separate requirements 1360 document. 1362 The dynamically changing topology, short connectivity, mobile 1363 transmitter and receivers, different antenna heights, and many-to- 1364 many communication types, make IEEE 802.11-OCB links significantly 1365 different from other IEEE 802.11 links. Any IPv6 mechanism operating 1366 on IEEE 802.11-OCB link MUST support strong link asymmetry, spatio- 1367 temporal link quality, fast address resolution and transmission. 1369 IEEE 802.11-OCB strongly differs from other 802.11 systems to operate 1370 outside of the context of a Basic Service Set. This means in 1371 practice that IEEE 802.11-OCB does not rely on a Base Station for all 1372 Basic Service Set management. In particular, IEEE 802.11-OCB SHALL 1373 NOT use beacons. Any IPv6 mechanism requiring L2 services from IEEE 1374 802.11 beacons MUST support an alternative service. 1376 Channel scanning being disabled, IPv6 over IEEE 802.11-OCB MUST 1377 implement a mechanism for transmitter and receiver to converge to a 1378 common channel. 1380 Authentication not being possible, IPv6 over IEEE 802.11-OCB MUST 1381 implement an distributed mechanism to authenticate transmitters and 1382 receivers without the support of a DHCP server. 1384 Time synchronization not being available, IPv6 over IEEE 802.11-OCB 1385 MUST implement a higher layer mechanism for time synchronization 1386 between transmitters and receivers without the support of a NTP 1387 server. 1389 The IEEE 802.11-OCB link being asymmetric, IPv6 over IEEE 802.11-OCB 1390 MUST disable management mechanisms requesting acknowledgements or 1391 replies. 1393 The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE 1394 802.11-OCB SHOULD implement fast IPv6 mobility management mechanisms. 1396 C.3. Multiple interfaces 1398 There are considerations for 2 or more IEEE 802.11-OCB interface 1399 cards per vehicle. For each vehicle taking part in road traffic, one 1400 IEEE 802.11-OCB interface card could be fully allocated for Non IP 1401 safety-critical communication. Any other IEEE 802.11-OCB may be used 1402 for other type of traffic. 1404 The mode of operation of these other wireless interfaces is not 1405 clearly defined yet. One possibility is to consider each card as an 1406 independent network interface, with a specific MAC Address and a set 1407 of IPv6 addresses. Another possibility is to consider the set of 1408 these wireless interfaces as a single network interface (not 1409 including the IEEE 802.11-OCB interface used by Non IP safety 1410 critical communications). This will require specific logic to 1411 ensure, for example, that packets meant for a vehicle in front are 1412 actually sent by the radio in the front, or that multiple copies of 1413 the same packet received by multiple interfaces are treated as a 1414 single packet. Treating each wireless interface as a separate 1415 network interface pushes such issues to the application layer. 1417 Certain privacy requirements imply that if these multiple interfaces 1418 are represented by many network interface, a single renumbering event 1419 SHALL cause renumbering of all these interfaces. If one MAC changed 1420 and another stayed constant, external observers would be able to 1421 correlate old and new values, and the privacy benefits of 1422 randomization would be lost. 1424 The privacy requirements of Non IP safety-critical communications 1425 imply that if a change of pseudonyme occurs, renumbering of all other 1426 interfaces SHALL also occur. 1428 C.4. MAC Address Generation 1430 When designing the IPv6 over 802.11-OCB address mapping, we will 1431 assume that the MAC Addresses will change during well defined 1432 "renumbering events". The 48 bits randomized MAC addresses will have 1433 the following characteristics: 1435 o Bit "Local/Global" set to "locally admninistered". 1437 o Bit "Unicast/Multicast" set to "Unicast". 1439 o 46 remaining bits set to a random value, using a random number 1440 generator that meets the requirements of [RFC4086]. 1442 The way to meet the randomization requirements is to retain 46 bits 1443 from the output of a strong hash function, such as SHA256, taking as 1444 input a 256 bit local secret, the "nominal" MAC Address of the 1445 interface, and a representation of the date and time of the 1446 renumbering event. 1448 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode 1450 For information, at the time of writing, this is the list of IEEE 1451 802.11 messages that may be transmitted in OCB mode, i.e. when 1452 dot11OCBActivated is true in a STA: 1454 o The STA may send management frames of subtype Action and, if the 1455 STA maintains a TSF Timer, subtype Timing Advertisement; 1457 o The STA may send control frames, except those of subtype PS-Poll, 1458 CF-End, and CF-End plus CFAck; 1460 o The STA may send data frames of subtype Data, Null, QoS Data, and 1461 QoS Null. 1463 Appendix E. Implementation Status 1465 This section describes an example of an IPv6 Packet captured over a 1466 IEEE 802.11-OCB link. 1468 By way of example we show that there is no modification in the 1469 headers when transmitted over 802.11-OCB networks - they are 1470 transmitted like any other 802.11 and Ethernet packets. 1472 We describe an experiment of capturing an IPv6 packet on an 1473 802.11-OCB link. In this experiment, the packet is an IPv6 Router 1474 Advertisement. This packet is emitted by a Router on its 802.11-OCB 1475 interface. The packet is captured on the Host, using a network 1476 protocol analyzer (e.g. Wireshark); the capture is performed in two 1477 different modes: direct mode and 'monitor' mode. The topology used 1478 during the capture is depicted below. 1480 +--------+ +-------+ 1481 | | 802.11-OCB Link | | 1482 ---| Router |--------------------------------| Host | 1483 | | | | 1484 +--------+ +-------+ 1486 During several capture operations running from a few moments to 1487 several hours, no message relevant to the BSSID contexts were 1488 captured (no Association Request/Response, Authentication Req/Resp, 1489 Beacon). This shows that the operation of 802.11-OCB is outside the 1490 context of a BSSID. 1492 Overall, the captured message is identical with a capture of an IPv6 1493 packet emitted on a 802.11b interface. The contents are precisely 1494 similar. 1496 E.1. Capture in Monitor Mode 1498 The IPv6 RA packet captured in monitor mode is illustrated below. 1499 The radio tap header provides more flexibility for reporting the 1500 characteristics of frames. The Radiotap Header is prepended by this 1501 particular stack and operating system on the Host machine to the RA 1502 packet received from the network (the Radiotap Header is not present 1503 on the air). The implementation-dependent Radiotap Header is useful 1504 for piggybacking PHY information from the chip's registers as data in 1505 a packet understandable by userland applications using Socket 1506 interfaces (the PHY interface can be, for example: power levels, data 1507 rate, ratio of signal to noise). 1509 The packet present on the air is formed by IEEE 802.11 Data Header, 1510 Logical Link Control Header, IPv6 Base Header and ICMPv6 Header. 1512 Radiotap Header v0 1513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1514 |Header Revision| Header Pad | Header length | 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 | Present flags | 1517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1518 | Data Rate | Pad | 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1521 IEEE 802.11 Data Header 1522 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1523 | Type/Subtype and Frame Ctrl | Duration | 1524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1525 | Receiver Address... 1526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1527 ... Receiver Address | Transmitter Address... 1528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1529 ... Transmitter Address | 1530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1531 | BSS Id... 1532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1533 ... BSS Id | Frag Number and Seq Number | 1534 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1535 Logical-Link Control Header 1536 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1537 | DSAP |I| SSAP |C| Control field | Org. code... 1538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1539 ... Organizational Code | Type | 1540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1542 IPv6 Base Header 1543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1544 |Version| Traffic Class | Flow Label | 1545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1546 | Payload Length | Next Header | Hop Limit | 1547 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1548 | | 1549 + + 1550 | | 1551 + Source Address + 1552 | | 1553 + + 1554 | | 1555 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1556 | | 1557 + + 1558 | | 1559 + Destination Address + 1560 | | 1561 + + 1562 | | 1563 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1565 Router Advertisement 1566 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1567 | Type | Code | Checksum | 1568 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1569 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 1570 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1571 | Reachable Time | 1572 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1573 | Retrans Timer | 1574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1575 | Options ... 1576 +-+-+-+-+-+-+-+-+-+-+-+- 1578 The value of the Data Rate field in the Radiotap header is set to 6 1579 Mb/s. This indicates the rate at which this RA was received. 1581 The value of the Transmitter address in the IEEE 802.11 Data Header 1582 is set to a 48bit value. The value of the destination address is 1583 33:33:00:00:00:1 (all-nodes multicast address). The value of the BSS 1584 Id field is ff:ff:ff:ff:ff:ff, which is recognized by the network 1585 protocol analyzer as being "broadcast". The Fragment number and 1586 sequence number fields are together set to 0x90C6. 1588 The value of the Organization Code field in the Logical-Link Control 1589 Header is set to 0x0, recognized as "Encapsulated Ethernet". The 1590 value of the Type field is 0x86DD (hexadecimal 86DD, or otherwise 1591 #86DD), recognized as "IPv6". 1593 A Router Advertisement is periodically sent by the router to 1594 multicast group address ff02::1. It is an icmp packet type 134. The 1595 IPv6 Neighbor Discovery's Router Advertisement message contains an 1596 8-bit field reserved for single-bit flags, as described in [RFC4861]. 1598 The IPv6 header contains the link local address of the router 1599 (source) configured via EUI-64 algorithm, and destination address set 1600 to ff02::1. Recent versions of network protocol analyzers (e.g. 1601 Wireshark) provide additional informations for an IP address, if a 1602 geolocalization database is present. In this example, the 1603 geolocalization database is absent, and the "GeoIP" information is 1604 set to unknown for both source and destination addresses (although 1605 the IPv6 source and destination addresses are set to useful values). 1606 This "GeoIP" can be a useful information to look up the city, 1607 country, AS number, and other information for an IP address. 1609 The Ethernet Type field in the logical-link control header is set to 1610 0x86dd which indicates that the frame transports an IPv6 packet. In 1611 the IEEE 802.11 data, the destination address is 33:33:00:00:00:01 1612 which is the corresponding multicast MAC address. The BSS id is a 1613 broadcast address of ff:ff:ff:ff:ff:ff. Due to the short link 1614 duration between vehicles and the roadside infrastructure, there is 1615 no need in IEEE 802.11-OCB to wait for the completion of association 1616 and authentication procedures before exchanging data. IEEE 1617 802.11-OCB enabled nodes use the wildcard BSSID (a value of all 1s) 1618 and may start communicating as soon as they arrive on the 1619 communication channel. 1621 E.2. Capture in Normal Mode 1623 The same IPv6 Router Advertisement packet described above (monitor 1624 mode) is captured on the Host, in the Normal mode, and depicted 1625 below. 1627 Ethernet II Header 1628 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1629 | Destination... 1630 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1631 ...Destination | Source... 1632 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1633 ...Source | 1634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1635 | Type | 1636 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1638 IPv6 Base Header 1639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1640 |Version| Traffic Class | Flow Label | 1641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1642 | Payload Length | Next Header | Hop Limit | 1643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1644 | | 1645 + + 1646 | | 1647 + Source Address + 1648 | | 1649 + + 1650 | | 1651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1652 | | 1653 + + 1654 | | 1655 + Destination Address + 1656 | | 1657 + + 1658 | | 1659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1661 Router Advertisement 1662 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1663 | Type | Code | Checksum | 1664 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1665 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 1666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1667 | Reachable Time | 1668 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1669 | Retrans Timer | 1670 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1671 | Options ... 1672 +-+-+-+-+-+-+-+-+-+-+-+- 1674 One notices that the Radiotap Header, the IEEE 802.11 Data Header and 1675 the Logical-Link Control Headers are not present. On the other hand, 1676 a new header named Ethernet II Header is present. 1678 The Destination and Source addresses in the Ethernet II header 1679 contain the same values as the fields Receiver Address and 1680 Transmitter Address present in the IEEE 802.11 Data Header in the 1681 "monitor" mode capture. 1683 The value of the Type field in the Ethernet II header is 0x86DD 1684 (recognized as "IPv6"); this value is the same value as the value of 1685 the field Type in the Logical-Link Control Header in the "monitor" 1686 mode capture. 1688 The knowledgeable experimenter will no doubt notice the similarity of 1689 this Ethernet II Header with a capture in normal mode on a pure 1690 Ethernet cable interface. 1692 An Adaptation layer is inserted on top of a pure IEEE 802.11 MAC 1693 layer, in order to adapt packets, before delivering the payload data 1694 to the applications. It adapts 802.11 LLC/MAC headers to Ethernet II 1695 headers. In further detail, this adaptation consists in the 1696 elimination of the Radiotap, 802.11 and LLC headers, and in the 1697 insertion of the Ethernet II header. In this way, IPv6 runs straight 1698 over LLC over the 802.11-OCB MAC layer; this is further confirmed by 1699 the use of the unique Type 0x86DD. 1701 Authors' Addresses 1703 Alexandre Petrescu 1704 CEA, LIST 1705 CEA Saclay 1706 Gif-sur-Yvette , Ile-de-France 91190 1707 France 1709 Phone: +33169089223 1710 Email: Alexandre.Petrescu@cea.fr 1712 Nabil Benamar 1713 Moulay Ismail University 1714 Morocco 1716 Phone: +212670832236 1717 Email: benamar73@gmail.com 1718 Jerome Haerri 1719 Eurecom 1720 Sophia-Antipolis 06904 1721 France 1723 Phone: +33493008134 1724 Email: Jerome.Haerri@eurecom.fr 1726 Christian Huitema 1727 Private Octopus Inc. 1728 Friday Harbor, WA 98250 1729 U.S.A. 1731 Email: huitema@huitema.net 1733 Jong-Hyouk Lee 1734 Sangmyung University 1735 31, Sangmyeongdae-gil, Dongnam-gu 1736 Cheonan 31066 1737 Republic of Korea 1739 Email: jonghyouk@smu.ac.kr 1741 Thierry Ernst 1742 YoGoKo 1743 France 1745 Email: thierry.ernst@yogoko.fr 1747 Tony Li 1748 Peloton Technology 1749 1060 La Avenida St. 1750 Mountain View, California 94043 1751 United States 1753 Phone: +16503957356 1754 Email: tony.li@tony.li