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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 16, 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 12, 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-06.txt 22 Abstract 24 In order to transmit IPv6 packets on IEEE 802.11 networks run outside 25 the context of a basic service set (OCB, earlier "802.11p") there is 26 a need to define a few parameters such as the supported Maximum 27 Transmission Unit size on the 802.11-OCB link, the header format 28 preceding the IPv6 header, the Type value within it, and others. 29 This document describes these parameters for IPv6 and IEEE 802.11-OCB 30 networks; it portrays the layering of IPv6 on 802.11-OCB similarly to 31 other known 802.11 and Ethernet layers - by using an Ethernet 32 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) has impact on IPv6 38 handover behaviour and on 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 16, 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 6 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 . . . . . . . . . . . . . . . . . . . . . . 11 81 5.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 13 82 5.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 14 83 5.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 14 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 . . . 27 99 Appendix C. Design Considerations . . . . . . . . . . . . . . . 29 100 C.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 29 101 C.2. Reliability Requirements . . . . . . . . . . . . . . . . 29 102 C.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 30 103 C.4. MAC Address Generation . . . . . . . . . . . . . . . . . 31 104 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode . . . . 31 105 Appendix E. Implementation Status . . . . . . . . . . . . . . . 32 106 E.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 32 107 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 (earlier known as 802.11p) [IEEE-802.11-2016]. 114 This involves the layering of IPv6 networking on top of the IEEE 115 802.11 MAC layer (with an LLC layer). Compared to running IPv6 over 116 the Ethernet MAC layer, there is no modification required to the 117 standards: IPv6 works fine directly over 802.11-OCB too (with an LLC 118 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 a flag in the Management Information Base. 124 That flag is named "OCBActivated". Whenever OCBActivated is set to 125 true the feature it relates to, or represents, an earlier 802.11p 126 feature. For example, an 802.11 STAtion operating outside the 127 context of a basic service set has the OCBActivated flag set. Such a 128 station, when it has the flag set, uses a BSS identifier equal to 129 ff:ff:ff:ff:ff:ff. 131 The IPv6 network layer operates on 802.11-OCB in the same manner as 132 it operates on 802.11 WiFi, with a few particular exceptions. The 133 IPv6 network layer operates on WiFi by involving an Ethernet 134 Adaptation Layer; this Ethernet Adaptation Layer maps 802.11 headers 135 to Ethernet II headers. The operation of IP on Ethernet is described 136 in [RFC1042], [RFC2464] and [I-D.hinden-6man-rfc2464bis]. The 137 situation of IPv6 networking layer on Ethernet Adaptation Layer is 138 illustrated below: 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 | IPv6 | 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 | Ethernet Adaptation Layer | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | 802.11 WiFi MAC | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | 802.11 WiFi PHY | 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 (in the above figure, a WiFi profile is represented; this is used 151 also for OCB profile.) 153 A more theoretical and detailed view of layer stacking, and 154 interfaces between the IP layer and 802.11-OCB layers, is illustrated 155 below. The IP layer operates on top of the EtherType Protocol 156 Discrimination (EPD); this Discrimination layer is described in IEEE 157 Std 802.3-2012; the interface between IPv6 and EPD is the LLC_SAP 158 (Link Layer Control Service Accesss Point). 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | IPv6 | 162 +-+-+-+-+-+-{ }+-+-+-+-+-+-+-+ 163 { LLC_SAP } 802.11-OCB 164 +-+-+-+-+-+-{ }+-+-+-+-+-+-+-+ Boundary 165 | EPD | | | 166 | | MLME | | 167 +-+-+-{ MAC_SAP }+-+-+-| MLME_SAP | 168 | MAC Sublayer | | | 802.11-OCB 169 | and ch. coord. | | SME | Services 170 +-+-+-{ PHY_SAP }+-+-+-+-+-+-+-| | 171 | | PLME | | 172 | PHY Layer | PLME_SAP | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 In addition to the description of interface between IP and MAC using 176 "Ethernet Adaptation Layer" and "Ethernet Protocol Discrimination 177 (EPD)" it is worth mentioning that SNAP [RFC1042] is used to carry 178 the IPv6 Ethertype. 180 However, there may be some deployment considerations helping optimize 181 the performances of running IPv6 over 802.11-OCB (e.g. in the case of 182 handovers between 802.11-OCB-enabled access routers, or the 183 consideration of using the IP security architecture [RFC4301]). 185 There are currently no specifications for handover between OCB links 186 since these are currently specified as LLC-1 links (i.e. 187 connectionless). Any handovers must be performed above the Data Link 188 Layer. To realize handovers between OCB links there is a need of 189 specific indicators to assist in the handover process. The 190 indicators may be IP Router Advertisements, or 802.11-OCB's Time 191 Advertisements, or higher layer messages such as the 'Basic Safety 192 Message' (in the US), or the 'Cooperative Awareness Message' (in the 193 EU), or the 'WAVE Routing Advertisement'. However, this document 194 does not describe handover behaviour. 196 The OCB operation is stripping off all existing 802.11 link-layer 197 security mechanisms. There is no encryption applied below the 198 network layer running on 802.11-OCB. At application layer, the IEEE 199 1609.2 document [IEEE-1609.2] does provide security services for 200 certain applications to use. A security mechanism provided at 201 networking layer, such as IPsec [RFC4301], may provide data security 202 protection to a wider range of applications. See the section 203 Security Considerations of this document, Section 6 205 We briefly introduce the vehicular communication scenarios where IEEE 206 802.11-OCB links are used. This is followed by a description of 207 differences in specification terms, between 802.11-OCB and 208 802.11a/b/g/n - we answer the question of what are the aspects 209 introduced by OCB mode to 802.11; the same aspects, but expressed in 210 terms of requirements to implementation, are listed in Appendix B.) 212 The document then concentrates on the parameters of layering IP over 213 802.11-OCB as over Ethernet: value of MTU, the Frame Format which 214 includes a description of an Ethernet Adaptation Layer, the forming 215 of Link-Local Addresses the rules for forming Interface Identifiers 216 for Stateless Autoconfiguration, the mechanisms for Address Mapping. 217 These are precisely the same as IPv6 over Ethernet [RFC2464]. A 218 reference is made to ad-hoc networking characteristics of the subnet 219 structure in OCB mode. 221 As an example, these characteristics of layering IPv6 straight over 222 LLC over 802.11-OCB MAC are illustrated by dissecting an IPv6 packet 223 captured over a 802.11-OCB link; this is described in the section 224 Appendix E. 226 In the published literature, many documents describe aspects related 227 to running IPv6 over 802.11-OCB: 228 [I-D.jeong-ipwave-vehicular-networking-survey]. 230 2. Terminology 232 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 233 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 234 document are to be interpreted as described in RFC 2119 [RFC2119]. 236 OBU (On-Board Unit): contrary to an RSU, an OBU is almost always 237 situated in a vehicle; it is a computer with at least two IP 238 interfaces; also, at least one IP interface runs in OCB mode of 239 802.11. It may be an IP router. 241 RSU (Road Side Unit): It is a Wireless Termination Point (WTP), as 242 defined in [RFC5415], or an Access Point (AP), or an Access Network 243 Router (ANR) defined in [RFC3753], with one key particularity: the 244 wireless PHY/MAC layer is configured to operate in 802.11-OCB mode. 245 The RSU communicates with the On board Unit (OBU) in the vehicle over 246 802.11 wireless link operating in OCB mode. An RSU MAY be connected 247 to the Internet, and MAY be an IP router. When it is connected to 248 the Internet, the term V2I (Vehicle to Internet) is relevant. 250 OCB (outside the context of a basic service set - BSS): A mode of 251 operation in which a STA is not a member of a BSS and does not 252 utilize IEEE Std 802.11 authentication, association, or data 253 confidentiality. 255 802.11-OCB, or 802.11-OCB: text in document IEEE 802.11-2016 that is 256 flagged by "dot11OCBActivated". The text flagged "dot11OCBActivated" 257 includes IEEE 802.11e for quality of service, 802.11j-2004 for half- 258 clocked operations and (what was known earlier as) 802.11p for 259 operation in the 5.9 GHz band and in mode OCB. 261 3. Communication Scenarios where IEEE 802.11-OCB Links are Used 263 The IEEE 802.11-OCB Networks are used for vehicular communications, 264 as 'Wireless Access in Vehicular Environments'. The IP communication 265 scenarios for these environments have been described in several 266 documents, among which we refer the reader to one recently updated 267 [I-D.petrescu-its-scenarios-reqs], about scenarios and requirements 268 for IP in Intelligent Transportation Systems. 270 The link model is the following: STA --- 802.11-OCB --- STA. In 271 vehicular networks, STAs can be RSUs and/or OBUs. While 802.11-OCB 272 is clearly specified, and the use of IPv6 over such link is not 273 radically new, the operating environment (vehicular networks) brings 274 in new perspectives. 276 The 802.11-OCB links form and terminate; nodes connected to these 277 links peer, and discover each other; the nodes are mobile. However, 278 the precise description of how links discover each other, peer and 279 manage mobility is not given in this document. 281 4. Aspects introduced by the OCB mode to 802.11 283 In the IEEE 802.11-OCB mode, all nodes in the wireless range can 284 directly communicate with each other without involving authentication 285 or association procedures. At link layer, it is necessary to set a 286 same channel number (or frequency) on two stations that need to 287 communicate with each other. Stations STA1 and STA2 can exchange IP 288 packets if they are set on the same channel. At IP layer, they then 289 discover each other by using the IPv6 Neighbor Discovery protocol. 291 Briefly, the IEEE 802.11-OCB mode has the following properties: 293 o The use by each node of a 'wildcard' BSSID (i.e., each bit of the 294 BSSID is set to 1) 296 o No IEEE 802.11 Beacon frames are transmitted 298 o No authentication is required in order to be able to communicate 300 o No association is needed in order to be able to communicate 302 o No encryption is provided in order to be able to communicate 304 o Flag dot11OCBActivated is set to true 306 All the nodes in the radio communication range (OBU and RSU) receive 307 all the messages transmitted (OBU and RSU) within the radio 308 communications range. The eventual conflict(s) are resolved by the 309 MAC CDMA function. 311 The following message exchange diagram illustrates a comparison 312 between traditional 802.11 and 802.11 in OCB mode. The 'Data' 313 messages can be IP packets such as HTTP or others. Other 802.11 314 management and control frames (non IP) may be transmitted, as 315 specified in the 802.11 standard. For information, the names of 316 these messages as currently specified by the 802.11 standard are 317 listed in Appendix D. 319 STA AP STA1 STA2 320 | | | | 321 |<------ Beacon -------| |<------ Data -------->| 322 | | | | 323 |---- Probe Req. ----->| |<------ Data -------->| 324 |<--- Probe Res. ------| | | 325 | | |<------ Data -------->| 326 |---- Auth Req. ------>| | | 327 |<--- Auth Res. -------| |<------ Data -------->| 328 | | | | 329 |---- Asso Req. ------>| |<------ Data -------->| 330 |<--- Asso Res. -------| | | 331 | | |<------ Data -------->| 332 |<------ Data -------->| | | 333 |<------ Data -------->| |<------ Data -------->| 335 (a) 802.11 Infrastructure mode (b) 802.11-OCB mode 337 The link 802.11-OCB was specified in IEEE Std 802.11p (TM) -2010 338 [IEEE-802.11p-2010] as an amendment to IEEE Std 802.11 (TM) -2007, 339 titled "Amendment 6: Wireless Access in Vehicular Environments". 340 Since then, this amendment has been included in IEEE 802.11(TM)-2016 341 [IEEE-802.11-2016], titled "IEEE Standard for Information 342 technology--Telecommunications and information exchange between 343 systems Local and metropolitan area networks--Specific requirements 344 Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer 345 (PHY) Specifications"; the modifications are diffused throughout 346 various sections (e.g. the Time Advertisement message described in 347 the earlier 802.11 (TM) p amendment is now described in section 348 'Frame formats', and the operation outside the context of a BSS 349 described in section 'MLME'). 351 In document 802.11-2016, anything qualified specifically as 352 "OCBActivated", or "outside the context of a basic service set" is 353 actually referring to OCB aspects introduced to 802.11. Note that in 354 earlier 802.11p documents the term "OCBEnabled" was used instead of 355 the current "OCBActivated". 357 In order to delineate the aspects introduced by 802.11-OCB to 802.11, 358 we refer to the earlier [IEEE-802.11p-2010]. The amendment is 359 concerned with vehicular communications, where the wireless link is 360 similar to that of Wireless LAN (using a PHY layer specified by 361 802.11a/b/g/n), but which needs to cope with the high mobility factor 362 inherent in scenarios of communications between moving vehicles, and 363 between vehicles and fixed infrastructure deployed along roads. 364 While 'p' is a letter just like 'a, b, g' and 'n' are, 'p' is 365 concerned more with MAC modifications, and a little with PHY 366 modifications; the others are mainly about PHY modifications. It is 367 possible in practice to combine a 'p' MAC with an 'a' PHY by 368 operating outside the context of a BSS with OFDM at 5.4GHz. 370 The 802.11-OCB links are specified to be compatible as much as 371 possible with the behaviour of 802.11a/b/g/n and future generation 372 IEEE WLAN links. From the IP perspective, an 802.11-OCB MAC layer 373 offers practically the same interface to IP as the WiFi and Ethernet 374 layers do (802.11a/b/g/n and 802.3). A packet sent by an OBU may be 375 received by one or multiple RSUs. The link-layer resolution is 376 performed by using the IPv6 Neighbor Discovery protocol. 378 To support this similarity statement (IPv6 is layered on top of LLC 379 on top of 802.11-OCB, in the same way that IPv6 is layered on top of 380 LLC on top of 802.11a/b/g/n (for WLAN) or layered on top of LLC on 381 top of 802.3 (for Ethernet)) it is useful to analyze the differences 382 between 802.11-OCB and 802.11 specifications. During this analysis, 383 we note that whereas 802.11-OCB lists relatively complex and numerous 384 changes to the MAC layer (and very little to the PHY layer), there 385 are only a few characteristics which may be important for an 386 implementation transmitting IPv6 packets on 802.11-OCB links. 388 The most important 802.11-OCB point which influences the IPv6 389 functioning is the OCB characteristic; an additional, less direct 390 influence, is the maximum bandwidth afforded by the PHY modulation/ 391 demodulation methods and channel access specified by 802.11-OCB. The 392 maximum bandwidth possible in 802.11-OCB is 12Mbit/s; this bandwidth 393 allows the operation of a wide range of protocols relying on IPv6. 395 o Operation Outside the Context of a BSS (OCB): the (earlier 396 802.11p) 802.11-OCB links are operated without a Basic Service Set 397 (BSS). This means that the frames IEEE 802.11 Beacon, Association 398 Request/Response, Authentication Request/Response, and similar, 399 are not used. The used identifier of BSS (BSSID) has a 400 hexadecimal value always 0xffffffffffff (48 '1' bits, represented 401 as MAC address ff:ff:ff:ff:ff:ff, or otherwise the 'wildcard' 402 BSSID), as opposed to an arbitrary BSSID value set by 403 administrator (e.g. 'My-Home-AccessPoint'). The OCB operation - 404 namely the lack of beacon-based scanning and lack of 405 authentication - should be taken into account when the Mobile IPv6 406 protocol [RFC6275] and the protocols for IP layer security 407 [RFC4301] are used. The way these protocols adapt to OCB is not 408 described in this document. 410 o Timing Advertisement: is a new message defined in 802.11-OCB, 411 which does not exist in 802.11a/b/g/n. This message is used by 412 stations to inform other stations about the value of time. It is 413 similar to the time as delivered by a GNSS system (Galileo, GPS, 414 ...) or by a cellular system. This message is optional for 415 implementation. 417 o Frequency range: this is a characteristic of the PHY layer, with 418 almost no impact to the interface between MAC and IP. However, it 419 is worth considering that the frequency range is regulated by a 420 regional authority (ARCEP, ETSI, FCC, etc.); as part of the 421 regulation process, specific applications are associated with 422 specific frequency ranges. In the case of 802.11-OCB, the 423 regulator associates a set of frequency ranges, or slots within a 424 band, to the use of applications of vehicular communications, in a 425 band known as "5.9GHz". The 5.9GHz band is different from the 426 2.4GHz and 5GHz bands used by Wireless LAN. However, as with 427 Wireless LAN, the operation of 802.11-OCB in "5.9GHz" bands is 428 exempt from owning a license in EU (in US the 5.9GHz is a licensed 429 band of spectrum; for the the fixed infrastructure an explicit FCC 430 autorization is required; for an onboard device a 'licensed-by- 431 rule' concept applies: rule certification conformity is required); 432 however technical conditions are different than those of the bands 433 "2.4GHz" or "5GHz". On one hand, the allowed power levels, and 434 implicitly the maximum allowed distance between vehicles, is of 435 33dBm for 802.11-OCB (in Europe), compared to 20 dBm for Wireless 436 LAN 802.11a/b/g/n; this leads to a maximum distance of 437 approximately 1km, compared to approximately 50m. On the other 438 hand, specific conditions related to congestion avoidance, jamming 439 avoidance, and radar detection are imposed on the use of DSRC (in 440 US) and on the use of frequencies for Intelligent Transportation 441 Systems (in EU), compared to Wireless LAN (802.11a/b/g/n). 443 o Prohibition of IPv6 on some channels relevant for IEEE 802.11-OCB, 444 as opposed to IPv6 not being prohibited on any channel on which 445 802.11a/b/g/n runs: 447 * Some channels are reserved for safety communications; the IPv6 448 packets should not be sent on these channels. 450 * At the time of writing, the prohibition is explicit at higher 451 layer protocols providing services to the application; these 452 higher layer protocols are specified in IEEE 1609 documents, 453 i.e. the "WAVE" stack. 455 * National or regional specifications and regulations specify the 456 use of different channels; these regulations must be followed. 458 o 'Half-rate' encoding: as the frequency range, this parameter is 459 related to PHY, and thus has not much impact on the interface 460 between the IP layer and the MAC layer. 462 o In vehicular communications using 802.11-OCB links, there are 463 strong privacy requirements with respect to addressing. While the 464 802.11-OCB standard does not specify anything in particular with 465 respect to MAC addresses, in these settings there exists a strong 466 need for dynamic change of these addresses (as opposed to the non- 467 vehicular settings - real wall protection - where fixed MAC 468 addresses do not currently pose some privacy risks). This is 469 further described in section Section 6. A relevant function is 470 described in IEEE 1609.3-2016 [IEEE-1609.3], clause 5.5.1 and IEEE 471 1609.4-2016 [IEEE-1609.4], clause 6.7. 473 Other aspects particular to 802.11-OCB, which are also particular to 474 802.11 (e.g. the 'hidden node' operation), may have an influence on 475 the use of transmission of IPv6 packets on 802.11-OCB networks. The 476 OCB subnet structure is described in section Section 5.6. 478 5. Layering of IPv6 over 802.11-OCB as over Ethernet 480 5.1. Maximum Transmission Unit (MTU) 482 The default MTU for IP packets on 802.11-OCB is 1500 octets. It is 483 the same value as IPv6 packets on Ethernet links, as specified in 484 [RFC2464]. This value of the MTU respects the recommendation that 485 every link in the Internet must have a minimum MTU of 1280 octets 486 (stated in [RFC8200], and the recommendations therein, especially 487 with respect to fragmentation). If IPv6 packets of size larger than 488 1500 bytes are sent on an 802.11-OCB interface card then the IP stack 489 will fragment. In case there are IP fragments, the field "Sequence 490 number" of the 802.11 Data header containing the IP fragment field is 491 increased. 493 Non-IP packets such as WAVE Short Message Protocol (WSMP) can be 494 delivered on 802.11-OCB links. Specifications of these packets are 495 out of scope of this document, and do not impose any limit on the MTU 496 size, allowing an arbitrary number of 'containers'. Non-IP packets 497 such as ETSI GeoNetworking packets have an MTU of 1492 bytes. The 498 operation of IPv6 over GeoNetworking is specified at 499 [ETSI-IPv6-GeoNetworking]. 501 5.2. Frame Format 503 IP packets are transmitted over 802.11-OCB as standard Ethernet 504 packets. As with all 802.11 frames, an Ethernet adaptation layer is 505 used with 802.11-OCB as well. This Ethernet Adaptation Layer 506 performing 802.11-to-Ethernet is described in Section 5.2.1. The 507 Ethernet Type code (EtherType) for IPv6 is 0x86DD (hexadecimal 86DD, 508 or otherwise #86DD). 510 The Frame format for transmitting IPv6 on 802.11-OCB networks is the 511 same as transmitting IPv6 on Ethernet networks, and is described in 512 section 3 of [RFC2464]. The frame format for transmitting IPv6 513 packets over Ethernet is illustrated below: 515 0 1 516 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 518 | Destination | 519 +- -+ 520 | Ethernet | 521 +- -+ 522 | Address | 523 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 524 | Source | 525 +- -+ 526 | Ethernet | 527 +- -+ 528 | Address | 529 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 530 |1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1| 531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 532 | IPv6 | 533 +- -+ 534 | header | 535 +- -+ 536 | and | 537 +- -+ 538 / payload ... / 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 540 (Each tic mark represents one bit.) 542 Ethernet II Fields: 544 Destination Ethernet Address 545 the MAC destination address. 547 Source Ethernet Address 548 the MAC source address. 550 1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1 551 binary representation of the EtherType value 0x86DD. 553 IPv6 header and payload 554 the IPv6 packet containing IPv6 header and payload. 556 5.2.1. Ethernet Adaptation Layer 558 In general, an 'adaptation' layer is inserted between a MAC layer and 559 the Networking layer. This is used to transform some parameters 560 between their form expected by the IP stack and the form provided by 561 the MAC layer. For example, an 802.15.4 adaptation layer may perform 562 fragmentation and reassembly operations on a MAC whose maximum Packet 563 Data Unit size is smaller than the minimum MTU recognized by the IPv6 564 Networking layer. Other examples involve link-layer address 565 transformation, packet header insertion/removal, and so on. 567 An Ethernet Adaptation Layer makes an 802.11 MAC look to IP 568 Networking layer as a more traditional Ethernet layer. At reception, 569 this layer takes as input the IEEE 802.11 Data Header and the 570 Logical-Link Layer Control Header and produces an Ethernet II Header. 571 At sending, the reverse operation is performed. 573 +--------------------+------------+-------------+---------+-----------+ 574 | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| 575 +--------------------+------------+-------------+---------+-----------+ 576 \ / \ / 577 ----------------------------- -------- 578 ^---------------------------------------------/ 579 | 580 802.11-to-Ethernet Adaptation Layer 581 | 582 v 583 +---------------------+-------------+---------+ 584 | Ethernet II Header | IPv6 Header | Payload | 585 +---------------------+-------------+---------+ 587 The Receiver and Transmitter Address fields in the 802.11 Data Header 588 contain the same values as the Destination and the Source Address 589 fields in the Ethernet II Header, respectively. The value of the 590 Type field in the LLC Header is the same as the value of the Type 591 field in the Ethernet II Header. 593 The ".11 Trailer" contains solely a 4-byte Frame Check Sequence. 595 The Ethernet Adaptation Layer performs operations in relation to IP 596 fragmentation and MTU. One of these operations is briefly described 597 in section Section 5.1. 599 In OCB mode, IPv6 packets can be transmitted either as "IEEE 802.11 600 Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in 601 the figure below. Some commercial OCB products use 802.11 Data, and 602 others 802.11 QoS data. In the future, both could be used. 604 +--------------------+-------------+-------------+---------+-----------+ 605 | 802.11 Data Header | LLC Header | IPv6 Header | Payload |.11 Trailer| 606 +--------------------+-------------+-------------+---------+-----------+ 608 or 610 +--------------------+-------------+-------------+---------+-----------+ 611 | 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload |.11 Trailer| 612 +--------------------+-------------+-------------+---------+-----------+ 614 The distinction between the two formats is given by the value of the 615 field "Type/Subtype". The value of the field "Type/Subtype" in the 616 802.11 Data header is 0x0020. The value of the field "Type/Subtype" 617 in the 802.11 QoS header is 0x0028. 619 The mapping between qos-related fields in the IPv6 header (e.g. 620 "Traffic Class", "Flow label") and fields in the "802.11 QoS Data 621 Header" (e.g. "QoS Control") are not specified in this document. 622 Guidance for a potential mapping is provided in 623 [I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB 624 mode. 626 5.3. Link-Local Addresses 628 The link-local address of an 802.11-OCB interface is formed in the 629 same manner as on an Ethernet interface. This manner is described in 630 section 5 of [RFC2464]. Additionally, if stable identifiers are 631 needed, it is recommended to follow the Recommendation on Stable IPv6 632 Interface Identifiers [RFC8064]. Additionally, if semantically 633 opaque Interface Identifiers are needed, a potential method for 634 generating semantically opaque Interface Identifiers with IPv6 635 Stateless Address Autoconfiguration is given in [RFC7217]. 637 5.4. Address Mapping 639 For unicast as for multicast, there is no change from the unicast and 640 multicast address mapping format of Ethernet interfaces, as defined 641 by sections 6 and 7 of [RFC2464]. 643 5.4.1. Address Mapping -- Unicast 645 The procedure for mapping IPv6 unicast addresses into Ethernet link- 646 layer addresses is described in [RFC4861]. The Source/Target Link- 647 layer Address option has the following form when the link-layer is 648 Ethernet. 650 0 1 651 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 652 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 653 | Type | Length | 654 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 | | 656 +- Ethernet -+ 657 | | 658 +- Address -+ 659 | | 660 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 662 Option fields: 664 Type 665 1 for Source Link-layer address. 666 2 for Target Link-layer address. 668 Length 669 1 (in units of 8 octets). 671 Ethernet Address 672 The 48 bit Ethernet IEEE 802 address, in canonical bit order. 674 5.4.2. Address Mapping -- Multicast 676 IPv6 protocols often make use of IPv6 multicast addresses in the 677 destination field of IPv6 headers. For example, an ICMPv6 link- 678 scoped Neighbor Advertisement is sent to the IPv6 address ff02::1 679 denoted "all-nodes" address. When transmitting these packets on 680 802.11-OCB links it is necessary to map the IPv6 address to a MAC 681 address. 683 The same mapping requirement applies to the link-scoped multicast 684 addresses of other IPv6 protocols as well. In DHCPv6, the 685 "All_DHCP_Servers" IPv6 multicast address ff02::1:2, and in OSPF the 686 "All_SPF_Routers" IPv6 multicast address ff02::5, need to be mapped 687 on a multicast MAC address. 689 An IPv6 packet with a multicast destination address DST, consisting 690 of the sixteen octets DST[1] through DST[16], is transmitted to the 691 IEEE 802.11-OCB MAC multicast address whose first two octets are the 692 value 0x3333 and whose last four octets are the last four octets of 693 DST. 695 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 696 |0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1| 697 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 698 | DST[13] | DST[14] | 699 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 700 | DST[15] | DST[16] | 701 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 703 A Group ID named TBD, of length 112bits is requested to IANA; this 704 Group ID signifies "All 80211OCB Interfaces Address". Only the least 705 32 significant bits of this "All 80211OCB Interfaces Address" will be 706 mapped to and from a MAC multicast address. 708 Transmitting IPv6 packets to multicast destinations over 802.11 links 709 proved to have some performance issues 710 [I-D.perkins-intarea-multicast-ieee802]. These issues may be 711 exacerbated in OCB mode. Solutions for these problems should 712 consider the OCB mode of operation. 714 5.5. Stateless Autoconfiguration 716 The Interface Identifier for an 802.11-OCB interface is formed using 717 the same rules as the Interface Identifier for an Ethernet interface; 718 this is described in section 4 of [RFC2464]. No changes are needed, 719 but some care must be taken when considering the use of the SLAAC 720 procedure. 722 The bits in the the interface identifier have no generic meaning and 723 the identifier should be treated as an opaque value. The bits 724 'Universal' and 'Group' in the identifier of an 802.11-OCB interface 725 are significant, as this is an IEEE link-layer address. The details 726 of this significance are described in [RFC7136]. 728 As with all Ethernet and 802.11 interface identifiers ([RFC7721]), 729 the identifier of an 802.11-OCB interface may involve privacy, MAC 730 address spoofing and IP address hijacking risks. A vehicle embarking 731 an On-Board Unit whose egress interface is 802.11-OCB may expose 732 itself to eavesdropping and subsequent correlation of data; this may 733 reveal data considered private by the vehicle owner; there is a risk 734 of being tracked; see the privacy considerations described in 735 Appendix C. 737 If stable Interface Identifiers are needed in order to form IPv6 738 addresses on 802.11-OCB links, it is recommended to follow the 739 recommendation in [RFC8064]. Additionally, if semantically opaque 740 Interface Identifiers are needed, a potential method for generating 741 semantically opaque Interface Identifiers with IPv6 Stateless Address 742 Autoconfiguration is given in [RFC7217]. 744 5.6. Subnet Structure 746 A subnet is formed by the external 802.11-OCB interfaces of vehicles 747 that are in close range (not their on-board interfaces). This 748 ephemeral subnet structure is strongly influenced by the mobility of 749 vehicles: the 802.11 hidden node effects appear. On another hand, 750 the structure of the internal subnets in each car is relatively 751 stable. 753 For routing purposes, a prefix exchange mechanism could be needed 754 between neighboring vehicles. 756 The 802.11 networks in OCB mode may be considered as 'ad-hoc' 757 networks. The addressing model for such networks is described in 758 [RFC5889]. 760 An addressing model involves several types of addresses, like 761 Globally-unique Addresses (GUA), Link-Local Addresses (LL) and Unique 762 Local Addresses (ULA). The subnet structure in 'ad-hoc' networks may 763 have characteristics that lead to difficulty of using GUAs derived 764 from a received prefix, but the LL addresses may be easier to use 765 since the prefix is constant. 767 6. Security Considerations 769 Any security mechanism at the IP layer or above that may be carried 770 out for the general case of IPv6 may also be carried out for IPv6 771 operating over 802.11-OCB. 773 802.11-OCB does not provide any cryptographic protection, because it 774 operates outside the context of a BSS (no Association Request/ 775 Response, no Challenge messages). Any attacker can therefore just 776 sit in the near range of vehicles, sniff the network (just set the 777 interface card's frequency to the proper range) and perform attacks 778 without needing to physically break any wall. Such a link is less 779 protected than commonly used links (wired link or protected 802.11). 781 The potential attack vectors are: MAC address spoofing, IP address 782 and session hijacking and privacy violation. 784 Within the IPsec Security Architecture [RFC4301], the IPsec AH and 785 ESP headers [RFC4302] and [RFC4303] respectively, its multicast 786 extensions [RFC5374], HTTPS [RFC2818] and SeND [RFC3971] protocols 787 can be used to protect communications. Further, the assistance of 788 proper Public Key Infrastructure (PKI) protocols [RFC4210] is 789 necessary to establish credentials. More IETF protocols are 790 available in the toolbox of the IP security protocol designer. 791 Certain ETSI protocols related to security protocols in Intelligent 792 Transportation Systems are described in [ETSI-sec-archi]. 794 As with all Ethernet and 802.11 interface identifiers, there may 795 exist privacy risks in the use of 802.11-OCB interface identifiers. 796 Moreover, in outdoors vehicular settings, the privacy risks are more 797 important than in indoors settings. New risks are induced by the 798 possibility of attacker sniffers deployed along routes which listen 799 for IP packets of vehicles passing by. For this reason, in the 800 802.11-OCB deployments, there is a strong necessity to use protection 801 tools such as dynamically changing MAC addresses. This may help 802 mitigate privacy risks to a certain level. On another hand, it may 803 have an impact in the way typical IPv6 address auto-configuration is 804 performed for vehicles (SLAAC would rely on MAC addresses amd would 805 hence dynamically change the affected IP address), in the way the 806 IPv6 Privacy addresses were used, and other effects. 808 7. IANA Considerations 810 A Group ID named TBD, of length 112bits is requested to IANA; this 811 Group ID signifies "All 80211OCB Interfaces Address". 813 8. Contributors 815 Romain Kuntz contributed extensively about IPv6 handovers between 816 links running outside the context of a BSS (802.11-OCB links). 818 Tim Leinmueller contributed the idea of the use of IPv6 over 819 802.11-OCB for distribution of certificates. 821 Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey 822 Voronov provided significant feedback on the experience of using IP 823 messages over 802.11-OCB in initial trials. 825 Michelle Wetterwald contributed extensively the MTU discussion, 826 offered the ETSI ITS perspective, and reviewed other parts of the 827 document. 829 9. Acknowledgements 831 The authors would like to thank Witold Klaudel, Ryuji Wakikawa, 832 Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan 833 Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray 834 Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan, 835 Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne, 836 Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, Erik Nordmark, 837 Bob Moskowitz, Andrew (Dryden?), Georg Mayer, Dorothy Stanley, Sandra 838 Cespedes, Mariano Falcitelli, Sri Gundavelli and William Whyte. 839 Their valuable comments clarified particular issues and generally 840 helped to improve the document. 842 Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB 843 drivers for linux and described how. 845 For the multicast discussion, the authors would like to thank Owen 846 DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and 847 participants to discussions in network working groups. 849 The authours would like to thank participants to the Birds-of- 850 a-Feather "Intelligent Transportation Systems" meetings held at IETF 851 in 2016. 853 10. References 855 10.1. Normative References 857 [I-D.ietf-tsvwg-ieee-802-11] 858 Szigeti, T., Henry, J., and F. Baker, "Diffserv to IEEE 859 802.11 Mapping", draft-ietf-tsvwg-ieee-802-11-07 (work in 860 progress), September 2017. 862 [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission 863 of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, 864 DOI 10.17487/RFC1042, February 1988, 865 . 867 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 868 Requirement Levels", BCP 14, RFC 2119, 869 DOI 10.17487/RFC2119, March 1997, 870 . 872 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 873 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 874 . 876 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 877 DOI 10.17487/RFC2818, May 2000, 878 . 880 [RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related 881 Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004, 882 . 884 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 885 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 886 RFC 3963, DOI 10.17487/RFC3963, January 2005, 887 . 889 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 890 "SEcure Neighbor Discovery (SEND)", RFC 3971, 891 DOI 10.17487/RFC3971, March 2005, 892 . 894 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 895 "Randomness Requirements for Security", BCP 106, RFC 4086, 896 DOI 10.17487/RFC4086, June 2005, 897 . 899 [RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen, 900 "Internet X.509 Public Key Infrastructure Certificate 901 Management Protocol (CMP)", RFC 4210, 902 DOI 10.17487/RFC4210, September 2005, 903 . 905 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 906 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 907 December 2005, . 909 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 910 DOI 10.17487/RFC4302, December 2005, 911 . 913 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 914 RFC 4303, DOI 10.17487/RFC4303, December 2005, 915 . 917 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 918 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 919 . 921 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 922 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 923 DOI 10.17487/RFC4861, September 2007, 924 . 926 [RFC5374] Weis, B., Gross, G., and D. Ignjatic, "Multicast 927 Extensions to the Security Architecture for the Internet 928 Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008, 929 . 931 [RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, 932 Ed., "Control And Provisioning of Wireless Access Points 933 (CAPWAP) Protocol Specification", RFC 5415, 934 DOI 10.17487/RFC5415, March 2009, 935 . 937 [RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing 938 Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889, 939 September 2010, . 941 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 942 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 943 2011, . 945 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 946 Bormann, "Neighbor Discovery Optimization for IPv6 over 947 Low-Power Wireless Personal Area Networks (6LoWPANs)", 948 RFC 6775, DOI 10.17487/RFC6775, November 2012, 949 . 951 [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 952 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, 953 February 2014, . 955 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 956 Interface Identifiers with IPv6 Stateless Address 957 Autoconfiguration (SLAAC)", RFC 7217, 958 DOI 10.17487/RFC7217, April 2014, 959 . 961 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 962 Considerations for IPv6 Address Generation Mechanisms", 963 RFC 7721, DOI 10.17487/RFC7721, March 2016, 964 . 966 [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, 967 "Recommendation on Stable IPv6 Interface Identifiers", 968 RFC 8064, DOI 10.17487/RFC8064, February 2017, 969 . 971 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 972 (IPv6) Specification", STD 86, RFC 8200, 973 DOI 10.17487/RFC8200, July 2017, 974 . 976 10.2. Informative References 978 [ETSI-IPv6-GeoNetworking] 979 "ETSI EN 302 636-6-1 v1.2.1 (2014-05), ETSI, European 980 Standard, Intelligent Transportation Systems (ITS); 981 Vehicular Communications; Geonetworking; Part 6: Internet 982 Integration; Sub-part 1: Transmission of IPv6 Packets over 983 Geonetworking Protocols. Downloaded on September 9th, 984 2017, freely available from ETSI website at URL 985 http://www.etsi.org/deliver/ 986 etsi_en/302600_302699/30263601/01.02.01_60/ 987 en_30263601v010201p.pdf". 989 [ETSI-sec-archi] 990 "ETSI TS 102 940 V1.2.1 (2016-11), ETSI Technical 991 Specification, Intelligent Transport Systems (ITS); 992 Security; ITS communications security architecture and 993 security management, November 2016. Dowloaded on 994 September 9th, 2017, freely available from ETSI website at 995 URL http://www.etsi.org/deliver/ 996 etsi_ts/102900_102999/102940/01.02.01_60/ 997 ts_102940v010201p.pdf". 999 [I-D.hinden-6man-rfc2464bis] 1000 Crawford, M. and R. Hinden, "Transmission of IPv6 Packets 1001 over Ethernet Networks", draft-hinden-6man-rfc2464bis-02 1002 (work in progress), March 2017. 1004 [I-D.jeong-ipwave-vehicular-networking-survey] 1005 Jeong, J., Cespedes, S., Benamar, N., Haerri, J., and M. 1006 Wetterwald, "Survey on IP-based Vehicular Networking for 1007 Intelligent Transportation Systems", draft-jeong-ipwave- 1008 vehicular-networking-survey-03 (work in progress), June 1009 2017. 1011 [I-D.perkins-intarea-multicast-ieee802] 1012 Perkins, C., Stanley, D., Kumari, W., and J. Zuniga, 1013 "Multicast Considerations over IEEE 802 Wireless Media", 1014 draft-perkins-intarea-multicast-ieee802-03 (work in 1015 progress), July 2017. 1017 [I-D.petrescu-its-scenarios-reqs] 1018 Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel, 1019 "Scenarios and Requirements for IP in Intelligent 1020 Transportation Systems", draft-petrescu-its-scenarios- 1021 reqs-03 (work in progress), October 2013. 1023 [IEEE-1609.2] 1024 "IEEE SA - 1609.2-2016 - IEEE Standard for Wireless Access 1025 in Vehicular Environments (WAVE) -- Security Services for 1026 Applications and Management Messages. Example URL 1027 http://ieeexplore.ieee.org/document/7426684/ accessed on 1028 August 17th, 2017.". 1030 [IEEE-1609.3] 1031 "IEEE SA - 1609.3-2016 - IEEE Standard for Wireless Access 1032 in Vehicular Environments (WAVE) -- Networking Services. 1033 Example URL http://ieeexplore.ieee.org/document/7458115/ 1034 accessed on August 17th, 2017.". 1036 [IEEE-1609.4] 1037 "IEEE SA - 1609.4-2016 - IEEE Standard for Wireless Access 1038 in Vehicular Environments (WAVE) -- Multi-Channel 1039 Operation. Example URL 1040 http://ieeexplore.ieee.org/document/7435228/ accessed on 1041 August 17th, 2017.". 1043 [IEEE-802.11-2016] 1044 "IEEE Standard 802.11-2016 - IEEE Standard for Information 1045 Technology - Telecommunications and information exchange 1046 between systems Local and metropolitan area networks - 1047 Specific requirements - Part 11: Wireless LAN Medium 1048 Access Control (MAC) and Physical Layer (PHY) 1049 Specifications. Status - Active Standard. Description 1050 retrieved freely on September 12th, 2017, at URL 1051 https://standards.ieee.org/findstds/ 1052 standard/802.11-2016.html". 1054 [IEEE-802.11p-2010] 1055 "IEEE Std 802.11p (TM)-2010, IEEE Standard for Information 1056 Technology - Telecommunications and information exchange 1057 between systems - Local and metropolitan area networks - 1058 Specific requirements, Part 11: Wireless LAN Medium Access 1059 Control (MAC) and Physical Layer (PHY) Specifications, 1060 Amendment 6: Wireless Access in Vehicular Environments; 1061 document freely available at URL 1062 http://standards.ieee.org/getieee802/ 1063 download/802.11p-2010.pdf retrieved on September 20th, 1064 2013.". 1066 Appendix A. ChangeLog 1068 The changes are listed in reverse chronological order, most recent 1069 changes appearing at the top of the list. 1071 From draft-ietf-ipwave-ipv6-over-80211ocb-05 to draft-ietf-ipwave- 1072 ipv6-over-80211ocb-06 1074 o Updated references of 802.11-OCB document from -2012 to the IEEE 1075 802.11-2016. 1077 o In the LL address section, and in SLAAC section, added references 1078 to 7217 opaque IIDs and 8064 stable IIDs. 1080 From draft-ietf-ipwave-ipv6-over-80211ocb-04 to draft-ietf-ipwave- 1081 ipv6-over-80211ocb-05 1083 o Lengthened the title and cleanded the abstract. 1085 o Added text suggesting LLs may be easy to use on OCB, rather than 1086 GUAs based on received prefix. 1088 o Added the risks of spoofing and hijacking. 1090 o Removed the text speculation on adoption of the TSA message. 1092 o Clarified that the ND protocol is used. 1094 o Clarified what it means "No association needed". 1096 o Added some text about how two STAs discover each other. 1098 o Added mention of external (OCB) and internal network (stable), in 1099 the subnet structure section. 1101 o Added phrase explaining that both .11 Data and .11 QoS Data 1102 headers are currently being used, and may be used in the future. 1104 o Moved the packet capture example into an Appendix Implementation 1105 Status. 1107 o Suggested moving the reliability requirements appendix out into 1108 another document. 1110 o Added a IANA Consiserations section, with content, requesting for 1111 a new multicast group "all OCB interfaces". 1113 o Added new OBU term, improved the RSU term definition, removed the 1114 ETTC term, replaced more occurences of 802.11p, 802.11 OCB with 1115 802.11-OCB. 1117 o References: 1119 * Added an informational reference to ETSI's IPv6-over- 1120 GeoNetworking. 1122 * Added more references to IETF and ETSI security protocols. 1124 * Updated some references from I-D to RFC, and from old RFC to 1125 new RFC numbers. 1127 * Added reference to multicast extensions to IPsec architecture 1128 RFC. 1130 * Added a reference to 2464-bis. 1132 * Removed FCC informative references, because not used. 1134 o Updated the affiliation of one author. 1136 o Reformulation of some phrases for better readability, and 1137 correction of typographical errors. 1139 From draft-ietf-ipwave-ipv6-over-80211ocb-03 to draft-ietf-ipwave- 1140 ipv6-over-80211ocb-04 1142 o Removed a few informative references pointing to Dx draft IEEE 1143 1609 documents. 1145 o Removed outdated informative references to ETSI documents. 1147 o Added citations to IEEE 1609.2, .3 and .4-2016. 1149 o Minor textual issues. 1151 From draft-ietf-ipwave-ipv6-over-80211ocb-02 to draft-ietf-ipwave- 1152 ipv6-over-80211ocb-03 1154 o Keep the previous text on multiple addresses, so remove talk about 1155 MIP6, NEMOv6 and MCoA. 1157 o Clarified that a 'Beacon' is an IEEE 802.11 frame Beacon. 1159 o Clarified the figure showing Infrastructure mode and OCB mode side 1160 by side. 1162 o Added a reference to the IP Security Architecture RFC. 1164 o Detailed the IPv6-per-channel prohibition paragraph which reflects 1165 the discussion at the last IETF IPWAVE WG meeting. 1167 o Added section "Address Mapping -- Unicast". 1169 o Added the ".11 Trailer" to pictures of 802.11 frames. 1171 o Added text about SNAP carrying the Ethertype. 1173 o New RSU definition allowing for it be both a Router and not 1174 necessarily a Router some times. 1176 o Minor textual issues. 1178 From draft-ietf-ipwave-ipv6-over-80211ocb-01 to draft-ietf-ipwave- 1179 ipv6-over-80211ocb-02 1181 o Replaced almost all occurences of 802.11p with 802.11-OCB, leaving 1182 only when explanation of evolution was necessary. 1184 o Shortened by removing parameter details from a paragraph in the 1185 Introduction. 1187 o Moved a reference from Normative to Informative. 1189 o Added text in intro clarifying there is no handover spec at IEEE, 1190 and that 1609.2 does provide security services. 1192 o Named the contents the fields of the EthernetII header (including 1193 the Ethertype bitstring). 1195 o Improved relationship between two paragraphs describing the 1196 increase of the Sequence Number in 802.11 header upon IP 1197 fragmentation. 1199 o Added brief clarification of "tracking". 1201 From draft-ietf-ipwave-ipv6-over-80211ocb-00 to draft-ietf-ipwave- 1202 ipv6-over-80211ocb-01 1204 o Introduced message exchange diagram illustrating differences 1205 between 802.11 and 802.11 in OCB mode. 1207 o Introduced an appendix listing for information the set of 802.11 1208 messages that may be transmitted in OCB mode. 1210 o Removed appendix sections "Privacy Requirements", "Authentication 1211 Requirements" and "Security Certificate Generation". 1213 o Removed appendix section "Non IP Communications". 1215 o Introductory phrase in the Security Considerations section. 1217 o Improved the definition of "OCB". 1219 o Introduced theoretical stacked layers about IPv6 and IEEE layers 1220 including EPD. 1222 o Removed the appendix describing the details of prohibiting IPv6 on 1223 certain channels relevant to 802.11-OCB. 1225 o Added a brief reference in the privacy text about a precise clause 1226 in IEEE 1609.3 and .4. 1228 o Clarified the definition of a Road Side Unit. 1230 o Removed the discussion about security of WSA (because is non-IP). 1232 o Removed mentioning of the GeoNetworking discussion. 1234 o Moved references to scientific articles to a separate 'overview' 1235 draft, and referred to it. 1237 Appendix B. Changes Needed on a software driver 802.11a to become a 1238 802.11-OCB driver 1240 The 802.11p amendment modifies both the 802.11 stack's physical and 1241 MAC layers but all the induced modifications can be quite easily 1242 obtained by modifying an existing 802.11a ad-hoc stack. 1244 Conditions for a 802.11a hardware to be 802.11-OCB compliant: 1246 o The chip must support the frequency bands on which the regulator 1247 recommends the use of ITS communications, for example using IEEE 1248 802.11-OCB layer, in France: 5875MHz to 5925MHz. 1250 o The chip must support the half-rate mode (the internal clock 1251 should be able to be divided by two). 1253 o The chip transmit spectrum mask must be compliant to the "Transmit 1254 spectrum mask" from the IEEE 802.11p amendment (but experimental 1255 environments tolerate otherwise). 1257 o The chip should be able to transmit up to 44.8 dBm when used by 1258 the US government in the United States, and up to 33 dBm in 1259 Europe; other regional conditions apply. 1261 Changes needed on the network stack in OCB mode: 1263 o Physical layer: 1265 * The chip must use the Orthogonal Frequency Multiple Access 1266 (OFDM) encoding mode. 1268 * The chip must be set in half-mode rate mode (the internal clock 1269 frequency is divided by two). 1271 * The chip must use dedicated channels and should allow the use 1272 of higher emission powers. This may require modifications to 1273 the regulatory domains rules, if used by the kernel to enforce 1274 local specific restrictions. Such modifications must respect 1275 the location-specific laws. 1277 MAC layer: 1279 * All management frames (beacons, join, leave, and others) 1280 emission and reception must be disabled except for frames of 1281 subtype Action and Timing Advertisement (defined below). 1283 * No encryption key or method must be used. 1285 * Packet emission and reception must be performed as in ad-hoc 1286 mode, using the wildcard BSSID (ff:ff:ff:ff:ff:ff). 1288 * The functions related to joining a BSS (Association Request/ 1289 Response) and for authentication (Authentication Request/Reply, 1290 Challenge) are not called. 1292 * The beacon interval is always set to 0 (zero). 1294 * Timing Advertisement frames, defined in the amendment, should 1295 be supported. The upper layer should be able to trigger such 1296 frames emission and to retrieve information contained in 1297 received Timing Advertisements. 1299 Appendix C. Design Considerations 1301 The networks defined by 802.11-OCB are in many ways similar to other 1302 networks of the 802.11 family. In theory, the encapsulation of IPv6 1303 over 802.11-OCB could be very similar to the operation of IPv6 over 1304 other networks of the 802.11 family. However, the high mobility, 1305 strong link asymmetry and very short connection makes the 802.11-OCB 1306 link significantly different from other 802.11 networks. Also, the 1307 automotive applications have specific requirements for reliability, 1308 security and privacy, which further add to the particularity of the 1309 802.11-OCB link. 1311 C.1. Vehicle ID 1313 In automotive networks it is required that each node is represented 1314 uniquely. Accordingly, a vehicle must be identified by at least one 1315 unique identifier. The current specification at ETSI and at IEEE 1316 1609 identifies a vehicle by its MAC address, which is obtained from 1317 the 802.11-OCB Network Interface Card (NIC). 1319 In case multiple 802.11-OCB NICs are present in one car, implicitely 1320 multiple vehicle IDs will be generated. Additionally, some software 1321 generates a random MAC address each time the computer boots; this 1322 constitutes an additional difficulty. 1324 A mechanim to uniquely identify a vehicle irrespectively to the 1325 multiplicity of NICs, or frequent MAC address generation, is 1326 necessary. 1328 C.2. Reliability Requirements 1330 This section may need to be moved out into a separate requirements 1331 document. 1333 The dynamically changing topology, short connectivity, mobile 1334 transmitter and receivers, different antenna heights, and many-to- 1335 many communication types, make IEEE 802.11-OCB links significantly 1336 different from other IEEE 802.11 links. Any IPv6 mechanism operating 1337 on IEEE 802.11-OCB link MUST support strong link asymmetry, spatio- 1338 temporal link quality, fast address resolution and transmission. 1340 IEEE 802.11-OCB strongly differs from other 802.11 systems to operate 1341 outside of the context of a Basic Service Set. This means in 1342 practice that IEEE 802.11-OCB does not rely on a Base Station for all 1343 Basic Service Set management. In particular, IEEE 802.11-OCB SHALL 1344 NOT use beacons. Any IPv6 mechanism requiring L2 services from IEEE 1345 802.11 beacons MUST support an alternative service. 1347 Channel scanning being disabled, IPv6 over IEEE 802.11-OCB MUST 1348 implement a mechanism for transmitter and receiver to converge to a 1349 common channel. 1351 Authentication not being possible, IPv6 over IEEE 802.11-OCB MUST 1352 implement an distributed mechanism to authenticate transmitters and 1353 receivers without the support of a DHCP server. 1355 Time synchronization not being available, IPv6 over IEEE 802.11-OCB 1356 MUST implement a higher layer mechanism for time synchronization 1357 between transmitters and receivers without the support of a NTP 1358 server. 1360 The IEEE 802.11-OCB link being asymmetric, IPv6 over IEEE 802.11-OCB 1361 MUST disable management mechanisms requesting acknowledgements or 1362 replies. 1364 The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE 1365 802.11-OCB SHOULD implement fast IPv6 mobility management mechanisms. 1367 C.3. Multiple interfaces 1369 There are considerations for 2 or more IEEE 802.11-OCB interface 1370 cards per vehicle. For each vehicle taking part in road traffic, one 1371 IEEE 802.11-OCB interface card could be fully allocated for Non IP 1372 safety-critical communication. Any other IEEE 802.11-OCB may be used 1373 for other type of traffic. 1375 The mode of operation of these other wireless interfaces is not 1376 clearly defined yet. One possibility is to consider each card as an 1377 independent network interface, with a specific MAC Address and a set 1378 of IPv6 addresses. Another possibility is to consider the set of 1379 these wireless interfaces as a single network interface (not 1380 including the IEEE 802.11-OCB interface used by Non IP safety 1381 critical communications). This will require specific logic to 1382 ensure, for example, that packets meant for a vehicle in front are 1383 actually sent by the radio in the front, or that multiple copies of 1384 the same packet received by multiple interfaces are treated as a 1385 single packet. Treating each wireless interface as a separate 1386 network interface pushes such issues to the application layer. 1388 Certain privacy requirements imply that if these multiple interfaces 1389 are represented by many network interface, a single renumbering event 1390 SHALL cause renumbering of all these interfaces. If one MAC changed 1391 and another stayed constant, external observers would be able to 1392 correlate old and new values, and the privacy benefits of 1393 randomization would be lost. 1395 The privacy requirements of Non IP safety-critical communications 1396 imply that if a change of pseudonyme occurs, renumbering of all other 1397 interfaces SHALL also occur. 1399 C.4. MAC Address Generation 1401 When designing the IPv6 over 802.11-OCB address mapping, we will 1402 assume that the MAC Addresses will change during well defined 1403 "renumbering events". The 48 bits randomized MAC addresses will have 1404 the following characteristics: 1406 o Bit "Local/Global" set to "locally admninistered". 1408 o Bit "Unicast/Multicast" set to "Unicast". 1410 o 46 remaining bits set to a random value, using a random number 1411 generator that meets the requirements of [RFC4086]. 1413 The way to meet the randomization requirements is to retain 46 bits 1414 from the output of a strong hash function, such as SHA256, taking as 1415 input a 256 bit local secret, the "nominal" MAC Address of the 1416 interface, and a representation of the date and time of the 1417 renumbering event. 1419 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode 1421 For information, at the time of writing, this is the list of IEEE 1422 802.11 messages that may be transmitted in OCB mode, i.e. when 1423 dot11OCBActivated is true in a STA: 1425 o The STA may send management frames of subtype Action and, if the 1426 STA maintains a TSF Timer, subtype Timing Advertisement; 1428 o The STA may send control frames, except those of subtype PS-Poll, 1429 CF-End, and CF-End plus CFAck; 1431 o The STA may send data frames of subtype Data, Null, QoS Data, and 1432 QoS Null. 1434 Appendix E. Implementation Status 1436 This section describese an example of an IPv6 Packet captured over a 1437 IEEE 802.11-OCB link. 1439 By way of example we show that there is no modification in the 1440 headers when transmitted over 802.11-OCB networks - they are 1441 transmitted like any other 802.11 and Ethernet packets. 1443 We describe an experiment of capturing an IPv6 packet on an 1444 802.11-OCB link. In this experiment, the packet is an IPv6 Router 1445 Advertisement. This packet is emitted by a Router on its 802.11-OCB 1446 interface. The packet is captured on the Host, using a network 1447 protocol analyzer (e.g. Wireshark); the capture is performed in two 1448 different modes: direct mode and 'monitor' mode. The topology used 1449 during the capture is depicted below. 1451 +--------+ +-------+ 1452 | | 802.11-OCB Link | | 1453 ---| Router |--------------------------------| Host | 1454 | | | | 1455 +--------+ +-------+ 1457 During several capture operations running from a few moments to 1458 several hours, no message relevant to the BSSID contexts were 1459 captured (no Association Request/Response, Authentication Req/Resp, 1460 Beacon). This shows that the operation of 802.11-OCB is outside the 1461 context of a BSSID. 1463 Overall, the captured message is identical with a capture of an IPv6 1464 packet emitted on a 802.11b interface. The contents are precisely 1465 similar. 1467 E.1. Capture in Monitor Mode 1469 The IPv6 RA packet captured in monitor mode is illustrated below. 1470 The radio tap header provides more flexibility for reporting the 1471 characteristics of frames. The Radiotap Header is prepended by this 1472 particular stack and operating system on the Host machine to the RA 1473 packet received from the network (the Radiotap Header is not present 1474 on the air). The implementation-dependent Radiotap Header is useful 1475 for piggybacking PHY information from the chip's registers as data in 1476 a packet understandable by userland applications using Socket 1477 interfaces (the PHY interface can be, for example: power levels, data 1478 rate, ratio of signal to noise). 1480 The packet present on the air is formed by IEEE 802.11 Data Header, 1481 Logical Link Control Header, IPv6 Base Header and ICMPv6 Header. 1483 Radiotap Header v0 1484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1485 |Header Revision| Header Pad | Header length | 1486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1487 | Present flags | 1488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1489 | Data Rate | Pad | 1490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1492 IEEE 802.11 Data Header 1493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1494 | Type/Subtype and Frame Ctrl | Duration | 1495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1496 | Receiver Address... 1497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1498 ... Receiver Address | Transmitter Address... 1499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1500 ... Transmitter Address | 1501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1502 | BSS Id... 1503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1504 ... BSS Id | Frag Number and Seq Number | 1505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1507 Logical-Link Control Header 1508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1509 | DSAP |I| SSAP |C| Control field | Org. code... 1510 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1511 ... Organizational Code | Type | 1512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1514 IPv6 Base Header 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 |Version| Traffic Class | Flow Label | 1517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1518 | Payload Length | Next Header | Hop Limit | 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | | 1521 + + 1522 | | 1523 + Source Address + 1524 | | 1525 + + 1526 | | 1527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1528 | | 1529 + + 1530 | | 1531 + Destination Address + 1532 | | 1533 + + 1534 | | 1535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1537 Router Advertisement 1538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1539 | Type | Code | Checksum | 1540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1541 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 1542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1543 | Reachable Time | 1544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1545 | Retrans Timer | 1546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1547 | Options ... 1548 +-+-+-+-+-+-+-+-+-+-+-+- 1550 The value of the Data Rate field in the Radiotap header is set to 6 1551 Mb/s. This indicates the rate at which this RA was received. 1553 The value of the Transmitter address in the IEEE 802.11 Data Header 1554 is set to a 48bit value. The value of the destination address is 1555 33:33:00:00:00:1 (all-nodes multicast address). The value of the BSS 1556 Id field is ff:ff:ff:ff:ff:ff, which is recognized by the network 1557 protocol analyzer as being "broadcast". The Fragment number and 1558 sequence number fields are together set to 0x90C6. 1560 The value of the Organization Code field in the Logical-Link Control 1561 Header is set to 0x0, recognized as "Encapsulated Ethernet". The 1562 value of the Type field is 0x86DD (hexadecimal 86DD, or otherwise 1563 #86DD), recognized as "IPv6". 1565 A Router Advertisement is periodically sent by the router to 1566 multicast group address ff02::1. It is an icmp packet type 134. The 1567 IPv6 Neighbor Discovery's Router Advertisement message contains an 1568 8-bit field reserved for single-bit flags, as described in [RFC4861]. 1570 The IPv6 header contains the link local address of the router 1571 (source) configured via EUI-64 algorithm, and destination address set 1572 to ff02::1. Recent versions of network protocol analyzers (e.g. 1574 Wireshark) provide additional informations for an IP address, if a 1575 geolocalization database is present. In this example, the 1576 geolocalization database is absent, and the "GeoIP" information is 1577 set to unknown for both source and destination addresses (although 1578 the IPv6 source and destination addresses are set to useful values). 1579 This "GeoIP" can be a useful information to look up the city, 1580 country, AS number, and other information for an IP address. 1582 The Ethernet Type field in the logical-link control header is set to 1583 0x86dd which indicates that the frame transports an IPv6 packet. In 1584 the IEEE 802.11 data, the destination address is 33:33:00:00:00:01 1585 which is the corresponding multicast MAC address. The BSS id is a 1586 broadcast address of ff:ff:ff:ff:ff:ff. Due to the short link 1587 duration between vehicles and the roadside infrastructure, there is 1588 no need in IEEE 802.11-OCB to wait for the completion of association 1589 and authentication procedures before exchanging data. IEEE 1590 802.11-OCB enabled nodes use the wildcard BSSID (a value of all 1s) 1591 and may start communicating as soon as they arrive on the 1592 communication channel. 1594 E.2. Capture in Normal Mode 1596 The same IPv6 Router Advertisement packet described above (monitor 1597 mode) is captured on the Host, in the Normal mode, and depicted 1598 below. 1600 Ethernet II Header 1601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1602 | Destination... 1603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1604 ...Destination | Source... 1605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1606 ...Source | 1607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1608 | Type | 1609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1611 IPv6 Base Header 1612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1613 |Version| Traffic Class | Flow Label | 1614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1615 | Payload Length | Next Header | Hop Limit | 1616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1617 | | 1618 + + 1619 | | 1620 + Source Address + 1621 | | 1622 + + 1623 | | 1624 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1625 | | 1626 + + 1627 | | 1628 + Destination Address + 1629 | | 1630 + + 1631 | | 1632 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1634 Router Advertisement 1635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1636 | Type | Code | Checksum | 1637 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1638 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 1639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1640 | Reachable Time | 1641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1642 | Retrans Timer | 1643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1644 | Options ... 1645 +-+-+-+-+-+-+-+-+-+-+-+- 1647 One notices that the Radiotap Header, the IEEE 802.11 Data Header and 1648 the Logical-Link Control Headers are not present. On the other hand, 1649 a new header named Ethernet II Header is present. 1651 The Destination and Source addresses in the Ethernet II header 1652 contain the same values as the fields Receiver Address and 1653 Transmitter Address present in the IEEE 802.11 Data Header in the 1654 "monitor" mode capture. 1656 The value of the Type field in the Ethernet II header is 0x86DD 1657 (recognized as "IPv6"); this value is the same value as the value of 1658 the field Type in the Logical-Link Control Header in the "monitor" 1659 mode capture. 1661 The knowledgeable experimenter will no doubt notice the similarity of 1662 this Ethernet II Header with a capture in normal mode on a pure 1663 Ethernet cable interface. 1665 An Adaptation layer is inserted on top of a pure IEEE 802.11 MAC 1666 layer, in order to adapt packets, before delivering the payload data 1667 to the applications. It adapts 802.11 LLC/MAC headers to Ethernet II 1668 headers. In further detail, this adaptation consists in the 1669 elimination of the Radiotap, 802.11 and LLC headers, and in the 1670 insertion of the Ethernet II header. In this way, IPv6 runs straight 1671 over LLC over the 802.11-OCB MAC layer; this is further confirmed by 1672 the use of the unique Type 0x86DD. 1674 Authors' Addresses 1676 Alexandre Petrescu 1677 CEA, LIST 1678 CEA Saclay 1679 Gif-sur-Yvette , Ile-de-France 91190 1680 France 1682 Phone: +33169089223 1683 Email: Alexandre.Petrescu@cea.fr 1685 Nabil Benamar 1686 Moulay Ismail University 1687 Morocco 1689 Phone: +212670832236 1690 Email: benamar73@gmail.com 1691 Jerome Haerri 1692 Eurecom 1693 Sophia-Antipolis 06904 1694 France 1696 Phone: +33493008134 1697 Email: Jerome.Haerri@eurecom.fr 1699 Christian Huitema 1700 Private Octopus Inc. 1701 Friday Harbor, WA 98250 1702 U.S.A. 1704 Email: huitema@huitema.net 1706 Jong-Hyouk Lee 1707 Sangmyung University 1708 31, Sangmyeongdae-gil, Dongnam-gu 1709 Cheonan 31066 1710 Republic of Korea 1712 Email: jonghyouk@smu.ac.kr 1714 Thierry Ernst 1715 YoGoKo 1716 France 1718 Email: thierry.ernst@yogoko.fr 1720 Tony Li 1721 Peloton Technology 1722 1060 La Avenida St. 1723 Mountain View, California 94043 1724 United States 1726 Phone: +16503957356 1727 Email: tony.li@tony.li