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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: September 13, 2017 Moulay Ismail University 6 J. Haerri 7 Eurecom 8 C. Huitema 10 J. Lee 11 Sangmyung University 12 T. Ernst 13 YoGoKo 14 T. Li 15 Peloton Technology 16 March 12, 2017 18 Transmission of IPv6 Packets over IEEE 802.11 Networks in mode Outside 19 the Context of a Basic Service Set (IPv6-over-80211ocb) 20 draft-ietf-ipwave-ipv6-over-80211ocb-02.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 recommended Maximum 27 Transmission Unit size, the header format preceding the IPv6 header, 28 the Type value within it, and others. This document describes these 29 parameters for IPv6 and IEEE 802.11 OCB networks; it portrays the 30 layering of IPv6 on 802.11 OCB similarly to other known 802.11 and 31 Ethernet layers - by using an Ethernet Adaptation Layer. 33 In addition, the document attempts to list what is different in 34 802.11 OCB (802.11p) compared to more 'traditional' 802.11a/b/g/n 35 layers, layers over which IPv6 protocols operates without issues. 36 Most notably, the operation outside the context of a BSS (OCB) has 37 impact on IPv6 handover behaviour and on IPv6 security. 39 An example of an IPv6 packet captured while transmitted over an IEEE 40 802.11 OCB link (802.11p) is given. 42 Status of This Memo 44 This Internet-Draft is submitted in full conformance with the 45 provisions of BCP 78 and BCP 79. 47 Internet-Drafts are working documents of the Internet Engineering 48 Task Force (IETF). Note that other groups may also distribute 49 working documents as Internet-Drafts. The list of current Internet- 50 Drafts is at http://datatracker.ietf.org/drafts/current/. 52 Internet-Drafts are draft documents valid for a maximum of six months 53 and may be updated, replaced, or obsoleted by other documents at any 54 time. It is inappropriate to use Internet-Drafts as reference 55 material or to cite them other than as "work in progress." 57 This Internet-Draft will expire on September 13, 2017. 59 Copyright Notice 61 Copyright (c) 2017 IETF Trust and the persons identified as the 62 document authors. All rights reserved. 64 This document is subject to BCP 78 and the IETF Trust's Legal 65 Provisions Relating to IETF Documents 66 (http://trustee.ietf.org/license-info) in effect on the date of 67 publication of this document. Please review these documents 68 carefully, as they describe your rights and restrictions with respect 69 to this document. Code Components extracted from this document must 70 include Simplified BSD License text as described in Section 4.e of 71 the Trust Legal Provisions and are provided without warranty as 72 described in the Simplified BSD License. 74 Table of Contents 76 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 77 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 78 3. Communication Scenarios where IEEE 802.11 OCB Links are Used 6 79 4. Aspects introduced by the OCB mode to 802.11 . . . . . . . . 6 80 5. Layering of IPv6 over 802.11-OCB as over Ethernet . . . . . . 10 81 5.1. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . 10 82 5.2. Frame Format . . . . . . . . . . . . . . . . . . . . . . 10 83 5.2.1. Ethernet Adaptation Layer . . . . . . . . . . . . . . 11 84 5.3. Link-Local Addresses . . . . . . . . . . . . . . . . . . 13 85 5.4. Address Mapping . . . . . . . . . . . . . . . . . . . . . 13 86 5.4.1. Address Mapping -- Unicast . . . . . . . . . . . . . 13 87 5.4.2. Address Mapping -- Multicast . . . . . . . . . . . . 13 88 5.5. Stateless Autoconfiguration . . . . . . . . . . . . . . . 14 89 5.6. Subnet Structure . . . . . . . . . . . . . . . . . . . . 15 90 6. Example IPv6 Packet captured over a IEEE 802.11-OCB link . . 15 91 6.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 16 92 6.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 18 93 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 94 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 95 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 96 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 97 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 98 11.1. Normative References . . . . . . . . . . . . . . . . . . 22 99 11.2. Informative References . . . . . . . . . . . . . . . . . 23 100 Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 26 101 Appendix B. Changes Needed on a software driver 802.11a to 102 become a 802.11-OCB driver . . . 27 103 Appendix C. Design Considerations . . . . . . . . . . . . . . . 29 104 C.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 29 105 C.2. Reliability Requirements . . . . . . . . . . . . . . . . 29 106 C.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 30 107 C.4. MAC Address Generation . . . . . . . . . . . . . . . . . 31 108 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode . . . . 31 109 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 111 1. Introduction 113 This document describes the transmission of IPv6 packets on IEEE Std 114 802.11 OCB networks (earlier known as 802.11p). This involves the 115 layering of IPv6 networking on top of the IEEE 802.11 MAC layer (with 116 an LLC layer). Compared to running IPv6 over the Ethernet MAC layer, 117 there is no modification required to the standards: IPv6 works fine 118 directly over 802.11 OCB too (with an LLC layer). 120 The term "802.11p" is an earlier definition. As of year 2012, the 121 behaviour of "802.11p" networks has been rolled in the document IEEE 122 Std 802.11-2012. In this document the term 802.11p disappears. 123 Instead, each 802.11p feature is conditioned by a flag in the 124 Management Information Base. That flag is named "OCBActivated". 125 Whenever OCBActivated is set to true the feature it relates to 126 represents an earlier 802.11p feature. For example, an 802.11 127 STAtion operating outside the context of a basic service set has the 128 OCBActivated flag set. Such a station, when it has the flag set, it 129 uses a BSS identifier equal to ff:ff:ff:ff:ff:ff. 131 In the following text we use the term "802.11p" to mean 802.11-2012 132 OCB. 134 The IPv6 network layer operates on 802.11 OCB in the same manner as 135 it operates on 802.11 WiFi. The IPv6 network layer operates on WiFi 136 by involving an Ethernet Adaptation Layer; this Ethernet Adaptation 137 Layer converts between 802.11 Headers and Ethernet II headers. The 138 operation of IP on Ethernet is described in [RFC1042] and [RFC2464]. 139 The situation of IPv6 networking layer on Ethernet Adaptation Layer 140 is illustrated below: 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 | IPv6 | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | Ethernet Adaptation Layer | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | 802.11 WiFi MAC | 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | 802.11 WiFi PHY | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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 However, there may be some deployment considerations helping optimize 175 the performances of running IPv6 over 802.11-OCB (e.g. in the case of 176 handovers between 802.11 OCB-enabled access routers, or the 177 consideration of using the IP security layer). 179 There are currently no specifications for handover between OCB links 180 since these are currently specified as LLC-1 links (i.e. 181 connectionless). Any handovers must be performed above the Data Link 182 Layer. Also, while there is no encryption applied below the network 183 layer using 802.11p, 1609.2 does provide security services for 184 applications to use so that there can easily be data security over 185 the air without invoking IPsec. 187 We briefly introduce the vehicular communication scenarios where IEEE 188 802.11-OCB links are used. This is followed by a description of 189 differences in specification terms, between 802.11 OCB and 190 802.11a/b/g/n (and the same differences expressed in terms of 191 requirements to software implementation are listed in Appendix B.) 193 The document then concentrates on the parameters of layering IP over 194 802.11 OCB as over Ethernet: value of MTU, the contents of Frame 195 Format, the rules for forming Interface Identifiers, the mechanism 196 for Address Mapping and for State-less Address Auto-configuration. 197 These are precisely the same as IPv6 over Ethernet [RFC2464]. 199 As an example, these characteristics of layering IPv6 straight over 200 LLC over 802.11 OCB MAC are illustrated by dissecting an IPv6 packet 201 captured over a 802.11 OCB link; this is described in the section 202 Section 6. 204 A couple of points can be considered as different, although they are 205 not required in order to have a working implementation of IPv6-over- 206 802.11-OCB. These points are consequences of the OCB operation which 207 is particular to 802.11 OCB (Outside the Context of a BSS). First, 208 the handovers between OCB links need specific behaviour for IP Router 209 Advertisements, or otherwise 802.11 OCB's Time Advertisement, or of 210 higher layer messages such as the 'Basic Safety Message' (in the US) 211 or the 'Cooperative Awareness Message' (in the EU) or the 'WAVE 212 Routing Advertisement'; second, the IP security mechanisms are 213 necessary, since OCB means that 802.11 is stripped of all 802.11 214 link-layer security; a small additional security aspect which is 215 shared between 802.11 OCB and other 802.11 links is the privacy 216 concerns related to the address formation mechanisms. 218 In the published literature, many documents describe aspects related 219 to running IPv6 over 802.11 OCB: 220 [I-D.jeong-ipwave-vehicular-networking-survey]. 222 2. Terminology 224 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 225 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 226 document are to be interpreted as described in RFC 2119 [RFC2119]. 228 RSU: Road Side Unit. An IP router equipped with, or connected to, at 229 least one interface that is 802.11 and that is an interface that 230 operates in OCB mode. 232 OCB: outside the context of a basic service set (BSS): A mode of 233 operation in which a STA is not a member of a BSS and does not 234 utilize IEEE Std 802.11 authentication, association, or data 235 confidentiality. 237 802.11-OCB, or 802.11 OCB: text in document IEEE 802.11-2012 that is 238 flagged by "dot11OCBActivated". This means: IEEE 802.11e for quality 239 of service; 802.11j-2004 for half-clocked operations; and (what was 240 known earlier as) 802.11p for operation in the 5.9 GHz band and in 241 mode OCB. 243 3. Communication Scenarios where IEEE 802.11 OCB Links are Used 245 The IEEE 802.11 OCB Networks are used for vehicular communications, 246 as 'Wireless Access in Vehicular Environments'. The IP communication 247 scenarios for these environments have been described in several 248 documents, among which we refer the reader to one recently updated 249 [I-D.petrescu-its-scenarios-reqs], about scenarios and requirements 250 for IP in Intelligent Transportation Systems. 252 4. Aspects introduced by the OCB mode to 802.11 254 In the IEEE 802.11 OCB mode, all nodes in the wireless range can 255 directly communicate with each other without authentication/ 256 association procedures. Briefly, the IEEE 802.11 OCB mode has the 257 following properties: 259 o The use by each node of a 'wildcard' BSSID (i.e., each bit of the 260 BSSID is set to 1) 262 o No Beacons transmitted 264 o No authentication required 266 o No association needed 268 o No encryption provided 270 o Flag dot11OCBActivated set to true 272 The following message exchange diagram illustrates a comparison 273 between traditional 802.11 and 802.11 in OCB mode. The 'Data' 274 messages can be IP messages such as the messages used in Stateless or 275 Stateful Address Auto-Configuration, or other IP messages. Other 276 802.11 management and control frames (non IP) may be transmitted, as 277 specified in the 802.11 standard. For information, the names of 278 these messages as currently specified by the 802.11 standard are 279 listed in Appendix D. 281 STA AP STA1 STA2 282 | | | | 283 |<------ Beacon -------| |<------ Data -------->| 284 | | |<------ Data -------->| 285 |---- Probe Req. ----->| |<------ Data -------->| 286 |<--- Probe Res. ------| |<------ Data -------->| 287 | | |<------ Data -------->| 288 |---- Auth Req. ------>| |<------ Data -------->| 289 |<--- Auth Res. -------| |<------ Data -------->| 290 | | |<------ Data -------->| 291 |---- Asso Req. ------>| |<------ Data -------->| 292 |<--- Asso Res. -------| |<------ Data -------->| 293 | | |<------ Data -------->| 294 |------- Data -------->| |<------ Data -------->| 295 |------- Data -------->| |<------ Data -------->| 297 (a) Traditional IEEE 802.11 (b) IEEE 802.11 OCB mode 299 The link 802.11 OCB was specified in IEEE Std 802.11p(TM)-2010 300 [ieee802.11p-2010] as an amendment to the 802.11 specifications, 301 titled "Amendment 6: Wireless Access in Vehicular Environments". 302 Since then, this amendment has been included in IEEE 802.11(TM)-2012 303 [ieee802.11-2012], titled "IEEE Standard for Information technology-- 304 Telecommunications and information exchange between systems Local and 305 metropolitan area networks--Specific requirements Part 11: Wireless 306 LAN Medium Access Control (MAC) and Physical Layer (PHY) 307 Specifications"; the modifications are diffused throughout various 308 sections (e.g. the Time Advertisement message described in the 309 earlier 802.11p ammendment is now described in section 'Frame 310 formats', and the operation outside the context of a BSS described in 311 section 'MLME'). 313 In document 802.11-2012, specifically anything referring 314 "OCBActivated", or "outside the context of a basic service set" is 315 actually referring to the 802.11p aspects introduced to 802.11. Note 316 that in earlier 802.11p documents the term "OCBEnabled" was used 317 instead of te current "OCBActivated". 319 In order to delineate the aspects introduced by 802.11 OCB to 802.11, 320 we refer to the earlier [ieee802.11p-2010]. The amendment is 321 concerned with vehicular communications, where the wireless link is 322 similar to that of Wireless LAN (using a PHY layer specified by 323 802.11a/b/g/n), but which needs to cope with the high mobility factor 324 inherent in scenarios of communications between moving vehicles, and 325 between vehicles and fixed infrastructure deployed along roads. 326 While 'p' is a letter just like 'a, b, g' and 'n' are, 'p' is 327 concerned more with MAC modifications, and a little with PHY 328 modifications; the others are mainly about PHY modifications. It is 329 possible in practice to combine a 'p' MAC with an 'a' PHY by 330 operating outside the context of a BSS with OFDM at 5.4GHz. 332 The 802.11 OCB links are specified to be compatible as much as 333 possible with the behaviour of 802.11a/b/g/n and future generation 334 IEEE WLAN links. From the IP perspective, an 802.11 OCB MAC layer 335 offers practically the same interface to IP as the WiFi and Ethernet 336 layers do (802.11a/b/g/n and 802.3). 338 To support this similarity statement (IPv6 is layered on top of LLC 339 on top of 802.11 OCB similarly as on top of LLC on top of 340 802.11a/b/g/n, and as on top of LLC on top of 802.3) it is useful to 341 analyze the differences between 802.11 OCB and 802.11 specifications. 342 Whereas the 802.11p amendment specifies relatively complex and 343 numerous changes to the MAC layer (and very little to the PHY layer), 344 we note there are only a few characteristics which may be important 345 for an implementation transmitting IPv6 packets on 802.11 OCB links. 347 In the list below, the only 802.11 OCB fundamental points which 348 influence IPv6 are the OCB operation and the 12Mbit/s maximum which 349 may be afforded by the IPv6 applications. 351 o Operation Outside the Context of a BSS (OCB): the (earlier 352 802.11p) 802.11-OCB links are operated without a Basic Service Set 353 (BSS). This means that the messages Beacon, Association Request/ 354 Response, Authentication Request/Response, and similar, are not 355 used. The used identifier of BSS (BSSID) has a hexadecimal value 356 always ff:ff:ff:ff:ff:ff (48 '1' bits, or the 'wildcard' BSSID), 357 as opposed to an arbitrary BSSID value set by administrator (e.g. 358 'My-Home-AccessPoint'). The OCB operation - namely the lack of 359 beacon-based scanning and lack of authentication - has a 360 potentially strong impact on the use of the Mobile IPv6 protocol 361 and on the protocols for IP layer security. 363 o Timing Advertisement: is a new message defined in 802.11-OCB, 364 which does not exist in 802.11a/b/g/n. This message is used by 365 stations to inform other stations about the value of time. It is 366 similar to the time as delivered by a GNSS system (Galileo, GPS, 367 ...) or by a cellular system. This message is optional for 368 implementation. At the date of writing, an experienced reviewer 369 considers that currently no field testing has used this message. 370 Another implementor considers this feature implemented in an 371 initial manner. In the future, it is speculated that this message 372 may be useful for very simple devices which may not have their own 373 hardware source of time (Galileo, GPS, cellular network), or by 374 vehicular devices situated in areas not covered by such network 375 (in tunnels, underground, outdoors but shaded by foliage or 376 buildings, in remote areas, etc.) 378 o Frequency range: this is a characteristic of the PHY layer, with 379 almost no impact to the interface between MAC and IP. However, it 380 is worth considering that the frequency range is regulated by a 381 regional authority (ARCEP, ETSI, FCC, etc.); as part of the 382 regulation process, specific applications are associated with 383 specific frequency ranges. In the case of 802.11-OCB, the 384 regulator associates a set of frequency ranges, or slots within a 385 band, to the use of applications of vehicular communications, in a 386 band known as "5.9GHz". This band is "5.9GHz" which is different 387 from the bands "2.4GHz" or "5GHz" used by Wireless LAN. However, 388 as with Wireless LAN, the operation of 802.11-OCB in "5.9GHz" 389 bands is exempt from owning a license in EU (in US the 5.9GHz is a 390 licensed band of spectrum; for the the fixed infrastructure an 391 explicit FCC autorization is required; for an onboard device a 392 'licensed-by-rule' concept applies: rule certification conformity 393 is required); however technical conditions are different than 394 those of the bands "2.4GHz" or "5GHz". On one hand, the allowed 395 power levels, and implicitly the maximum allowed distance between 396 vehicles, is of 33dBm for 802.11-OCB (in Europe), compared to 20 397 dBm for Wireless LAN 802.11a/b/g/n; this leads to a maximum 398 distance of approximately 1km, compared to approximately 50m. On 399 the hand, specific conditions related to congestion avoidance, 400 jamming avoidance, and radar detection are imposed on the use of 401 DSRC (in US) and on the use of frequencies for Intelligent 402 Transportation Systems (in EU), compared to Wireless LAN 403 (802.11a/b/g/n). 405 o Prohibition of IPv6 on some channels relevant for the PHY of IEEE 406 802.11-OCB, as opposed to IPv6 not being prohibited on any channel 407 on which 802.11a/b/g/n runs; at the time of writing, this 408 prohibition is explicit in IEEE 1609 documents. 410 o 'Half-rate' encoding: as the frequency range, this parameter is 411 related to PHY, and thus has not much impact on the interface 412 between the IP layer and the MAC layer. 414 o In vehicular communications using 802.11-OCB links, there are 415 strong privacy concerns with respect to addressing. While the 416 802.11-OCB standard does not specify anything in particular with 417 respect to MAC addresses, in these settings there exists a strong 418 need for dynamic change of these addresses (as opposed to the non- 419 vehicular settings - real wall protection - where fixed MAC 420 addresses do not currently pose some privacy risks). This is 421 further described in section Section 7. A relevant function is 422 described in IEEE 1609.3, clause 5.5.1 and IEEE 1609.4, clause 423 6.7. 425 Other aspects particular to 802.11-OCB which are also particular to 426 802.11 (e.g. the 'hidden node' operation) may have an influence on 427 the use of transmission of IPv6 packets on 802.11-OCB networks. The 428 subnet structure which may be assumed in 802.11-OCB networks is 429 strongly influenced by the mobility of vehicles. 431 5. Layering of IPv6 over 802.11-OCB as over Ethernet 433 5.1. Maximum Transmission Unit (MTU) 435 The default MTU for IP packets on 802.11-OCB is 1500 octets. It is 436 the same value as IPv6 packets on Ethernet links, as specified in 437 [RFC2464]. This value of the MTU respects the recommendation that 438 every link in the Internet must have a minimum MTU of 1280 octets 439 (stated in [RFC2460], and the recommendations therein, especially 440 with respect to fragmentation). If IPv6 packets of size larger than 441 1500 bytes are sent on an 802.11-OCB interface then the IP stack will 442 fragment. In case there are IP fragments, the field "Sequence 443 number" of the 802.11 Data header containing the IP fragment field is 444 increased. 446 Non-IP packets such as WAVE Short Message Protocol (WSMP) can be 447 delivered on 802.11-OCB links. Specifications of these packets are 448 out of scope of this document, and do not impose any limit on the MTU 449 size, allowing an arbitrary number of 'containers'. Non-IP packets 450 such as ETSI 'geonet' packets have an MTU of 1492 bytes. 452 The Equivalent Transmit Time on Channel is a concept that may be used 453 as an alternative to the MTU concept. A rate of transmission may be 454 specified as well. The ETTC, rate and MTU may be in direct 455 relationship. 457 5.2. Frame Format 459 IP packets are transmitted over 802.11-OCB as standard Ethernet 460 packets. As with all 802.11 frames, an Ethernet adaptation layer is 461 used with 802.11-OCB as well. This Ethernet Adaptation Layer 462 performing 802.11-to-Ethernet is described in Section 5.2.1. The 463 Ethernet Type code (EtherType) for IPv6 is 0x86DD (hexadecimal 86DD, 464 or otherwise #86DD). 466 The Frame format for transmitting IPv6 on 802.11-OCB networks is the 467 same as transmitting IPv6 on Ethernet networks, and is described in 468 section 3 of [RFC2464]. The frame format for transmitting IPv6 469 packets over Ethernet is illustrated below: 471 0 1 472 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 | Destination | 475 +- -+ 476 | Ethernet | 477 +- -+ 478 | Address | 479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 480 | Source | 481 +- -+ 482 | Ethernet | 483 +- -+ 484 | Address | 485 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 486 |1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1| 487 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 488 | IPv6 | 489 +- -+ 490 | header | 491 +- -+ 492 | and | 493 +- -+ 494 / payload ... / 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 496 (Each tic mark represents one bit.) 498 Ethernet II Fields: 500 o Destination Ethernet Address: the MAC destination address. 502 o Source Ethernet Address: the MAC source address. 504 o "1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1": binary representation of the 505 EtherType value 0x86DD. 507 o IPv6 header and payload: the IPv6 packet containing IPv6 header 508 and payload. 510 5.2.1. Ethernet Adaptation Layer 512 In general, an 'adaptation' layer is inserted between a MAC layer and 513 the Networking layer. This is used to transform some parameters 514 between their form expected by the IP stack and the form provided by 515 the MAC layer. For example, an 802.15.4 adaptation layer may perform 516 fragmentation and reassembly operations on a MAC whose maximum Packet 517 Data Unit size is smaller than the minimum MTU recognized by the IPv6 518 Networking layer. Other examples involve link-layer address 519 transformation, packet header insertion/removal, and so on. 521 An Ethernet Adaptation Layer makes an 802.11 MAC look to IP 522 Networking layer as a more traditional Ethernet layer. At reception, 523 this layer takes as input the IEEE 802.11 Data Header and the 524 Logical-Link Layer Control Header and produces an Ethernet II Header. 525 At sending, the reverse operation is performed. 527 +--------------------+-------------+-------------+---------+ 528 | 802.11 Data Header | LLC Header | IPv6 Header | Payload | 529 +--------------------+-------------+-------------+---------+ 530 ^ 531 | 532 802.11-to-Ethernet Adaptation Layer 533 | 534 v 536 +---------------------+-------------+---------+ 537 | Ethernet II Header | IPv6 Header | Payload | 538 +---------------------+-------------+---------+ 540 The Receiver and Transmitter Address fields in the 802.11 Data Header 541 contain the same values as the Destination and the Source Address 542 fields in the Ethernet II Header, respectively. The value of the 543 Type field in the LLC Header is the same as the value of the Type 544 field in the Ethernet II Header. 546 The Ethernet Adaptation Layer performs operations in relation to IP 547 fragmentation and MTU. One of these operations is briefly described 548 in section Section 5.1. 550 In OCB mode, IPv6 packets can be transmitted either as "IEEE 802.11 551 Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in 552 the following figure: 554 +--------------------+-------------+-------------+---------+ 555 | 802.11 Data Header | LLC Header | IPv6 Header | Payload | 556 +--------------------+-------------+-------------+---------+ 558 or 560 +--------------------+-------------+-------------+---------+ 561 | 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload | 562 +--------------------+-------------+-------------+---------+ 564 The distinction between the two formats is given by the value of the 565 field "Type/Subtype". The value of the field "Type/Subtype" in the 566 802.11 Data header is 0x0020. The value of the field "Type/Subtype" 567 in the 802.11 QoS header is 0x0028. 569 The mapping between qos-related fields in the IPv6 header (e.g. 570 "Traffic Class", "Flow label") and fields in the "802.11 QoS Data 571 Header" (e.g. "QoS Control") are not specified in this document. 572 Guidance for a potential mapping is provided in 573 [I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB 574 mode. 576 5.3. Link-Local Addresses 578 The link-local address of an 802.11-OCB interface is formed in the 579 same manner as on an Ethernet interface. This manner is described in 580 section 5 of [RFC2464]. 582 5.4. Address Mapping 584 For unicast as for multicast, there is no change from the unicast and 585 multicast address mapping format of Ethernet interfaces, as defined 586 by sections 6 and 7 of [RFC2464]. 588 5.4.1. Address Mapping -- Unicast 590 The procedure for mapping IPv6 unicast addresses into Ethernet link- 591 layer addresses is described in 593 5.4.2. Address Mapping -- Multicast 595 IPv6 protocols often make use of IPv6 multicast addresses in the 596 destination field of IPv6 headers. For example, an ICMPv6 link- 597 scoped Neighbor Advertisement is sent to the IPv6 address ff02::1 598 denoted "all-nodes" address. When transmitting these packets on 599 802.11-OCB links it is necessary to map the IPv6 address to a MAC 600 address. 602 The same mapping requirement applies to the link-scoped multicast 603 addresses of other IPv6 protocols as well. In DHCPv6, the 604 "All_DHCP_Servers" IPv6 multicast address ff02::1:2, and in OSPF the 605 "All_SPF_Routers" IPv6 multicast address ff02::5, need to be mapped 606 on a multicast MAC address. 608 An IPv6 packet with a multicast destination address DST, consisting 609 of the sixteen octets DST[1] through DST[16], is transmitted to the 610 IEEE 802.11-OCB MAC multicast address whose first two octets are the 611 value 0x3333 and whose last four octets are the last four octets of 612 DST. 614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 615 |0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1| 616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 617 | DST[13] | DST[14] | 618 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 | DST[15] | DST[16] | 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 A Group ID TBD of length 112bits may be requested from IANA; this 623 Group ID signifies "All 80211OCB Interfaces Address". Only the least 624 32 significant bits of this "All 80211OCB Interfaces Address" will be 625 mapped to and from a MAC multicast address. 627 Transmitting IPv6 packets to multicast destinations over 802.11 links 628 proved to have some performance issues 629 [I-D.perkins-intarea-multicast-ieee802]. These issues may be 630 exacerbated in OCB mode. Solutions for these problems should 631 consider the OCB mode of operation. 633 5.5. Stateless Autoconfiguration 635 The Interface Identifier for an 802.11-OCB interface is formed using 636 the same rules as the Interface Identifier for an Ethernet interface; 637 this is described in section 4 of [RFC2464]. No changes are needed, 638 but some care must be taken when considering the use of the SLAAC 639 procedure. 641 The bits in the the interface identifier have no generic meaning and 642 the identifier should be treated as an opaque value. The bits 643 'Universal' and 'Group' in the identifier of an 802.11-OCB interface 644 are significant, as this is an IEEE link-layer address. The details 645 of this significance are described in [I-D.ietf-6man-ug]. 647 As with all Ethernet and 802.11 interface identifiers ([RFC7721]), 648 the identifier of an 802.11-OCB interface may involve privacy risks. 649 A vehicle embarking an On-Board Unit whose egress interface is 650 802.11-OCB may expose itself to eavesdropping and subsequent 651 correlation of data; this may reveal data considered private by the 652 vehicle owner; there is a risk fo being tracked; see the privacy 653 considerations described in Appendix C. 655 If stable Interface Identifiers are needed in order to form IPv6 656 addresses on 802.11-OCB links, it is recommended to follow the 657 recommendation in [I-D.ietf-6man-default-iids]. 659 5.6. Subnet Structure 661 The 802.11 networks in OCB mode may be considered as 'ad-hoc' 662 networks. The addressing model for such networks is described in 663 [RFC5889]. 665 6. Example IPv6 Packet captured over a IEEE 802.11-OCB link 667 We remind that a main goal of this document is to make the case that 668 IPv6 works fine over 802.11-OCB networks. Consequently, this section 669 is an illustration of this concept and thus can help the implementer 670 when it comes to running IPv6 over IEEE 802.11-OCB. By way of 671 example we show that there is no modification in the headers when 672 transmitted over 802.11-OCB networks - they are transmitted like any 673 other 802.11 and Ethernet packets. 675 We describe an experiment of capturing an IPv6 packet on an 676 802.11-OCB link. In this experiment, the packet is an IPv6 Router 677 Advertisement. This packet is emitted by a Router on its 802.11-OCB 678 interface. The packet is captured on the Host, using a network 679 protocol analyzer (e.g. Wireshark); the capture is performed in two 680 different modes: direct mode and 'monitor' mode. The topology used 681 during the capture is depicted below. 683 +--------+ +-------+ 684 | | 802.11-OCB Link | | 685 ---| Router |--------------------------------| Host | 686 | | | | 687 +--------+ +-------+ 689 During several capture operations running from a few moments to 690 several hours, no message relevant to the BSSID contexts were 691 captured (no Association Request/Response, Authentication Req/Resp, 692 Beacon). This shows that the operation of 802.11-OCB is outside the 693 context of a BSSID. 695 Overall, the captured message is identical with a capture of an IPv6 696 packet emitted on a 802.11b interface. The contents are precisely 697 similar. 699 6.1. Capture in Monitor Mode 701 The IPv6 RA packet captured in monitor mode is illustrated below. 702 The radio tap header provides more flexibility for reporting the 703 characteristics of frames. The Radiotap Header is prepended by this 704 particular stack and operating system on the Host machine to the RA 705 packet received from the network (the Radiotap Header is not present 706 on the air). The implementation-dependent Radiotap Header is useful 707 for piggybacking PHY information from the chip's registers as data in 708 a packet understandable by userland applications using Socket 709 interfaces (the PHY interface can be, for example: power levels, data 710 rate, ratio of signal to noise). 712 The packet present on the air is formed by IEEE 802.11 Data Header, 713 Logical Link Control Header, IPv6 Base Header and ICMPv6 Header. 715 Radiotap Header v0 716 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 717 |Header Revision| Header Pad | Header length | 718 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 719 | Present flags | 720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 721 | Data Rate | Pad | 722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 724 IEEE 802.11 Data Header 725 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 726 | Type/Subtype and Frame Ctrl | Duration | 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | Receiver Address... 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 ... Receiver Address | Transmitter Address... 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 732 ... Transmitter Address | 733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 734 | BSS Id... 735 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 736 ... BSS Id | Frag Number and Seq Number | 737 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 738 Logical-Link Control Header 739 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 740 | DSAP |I| SSAP |C| Control field | Org. code... 741 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 742 ... Organizational Code | Type | 743 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 745 IPv6 Base Header 746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 747 |Version| Traffic Class | Flow Label | 748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 749 | Payload Length | Next Header | Hop Limit | 750 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 | | 752 + + 753 | | 754 + Source Address + 755 | | 756 + + 757 | | 758 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 759 | | 760 + + 761 | | 762 + Destination Address + 763 | | 764 + + 765 | | 766 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 768 Router Advertisement 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 | Type | Code | Checksum | 771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 772 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 774 | Reachable Time | 775 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 776 | Retrans Timer | 777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 778 | Options ... 779 +-+-+-+-+-+-+-+-+-+-+-+- 781 The value of the Data Rate field in the Radiotap header is set to 6 782 Mb/s. This indicates the rate at which this RA was received. 784 The value of the Transmitter address in the IEEE 802.11 Data Header 785 is set to a 48bit value. The value of the destination address is 786 33:33:00:00:00:1 (all-nodes multicast address). The value of the BSS 787 Id field is ff:ff:ff:ff:ff:ff, which is recognized by the network 788 protocol analyzer as being "broadcast". The Fragment number and 789 sequence number fields are together set to 0x90C6. 791 The value of the Organization Code field in the Logical-Link Control 792 Header is set to 0x0, recognized as "Encapsulated Ethernet". The 793 value of the Type field is 0x86DD (hexadecimal 86DD, or otherwise 794 #86DD), recognized as "IPv6". 796 A Router Advertisement is periodically sent by the router to 797 multicast group address ff02::1. It is an icmp packet type 134. The 798 IPv6 Neighbor Discovery's Router Advertisement message contains an 799 8-bit field reserved for single-bit flags, as described in [RFC4861]. 801 The IPv6 header contains the link local address of the router 802 (source) configured via EUI-64 algorithm, and destination address set 803 to ff02::1. Recent versions of network protocol analyzers (e.g. 804 Wireshark) provide additional informations for an IP address, if a 805 geolocalization database is present. In this example, the 806 geolocalization database is absent, and the "GeoIP" information is 807 set to unknown for both source and destination addresses (although 808 the IPv6 source and destination addresses are set to useful values). 809 This "GeoIP" can be a useful information to look up the city, 810 country, AS number, and other information for an IP address. 812 The Ethernet Type field in the logical-link control header is set to 813 0x86dd which indicates that the frame transports an IPv6 packet. In 814 the IEEE 802.11 data, the destination address is 33:33:00:00:00:01 815 which is he corresponding multicast MAC address. The BSS id is a 816 broadcast address of ff:ff:ff:ff:ff:ff. Due to the short link 817 duration between vehicles and the roadside infrastructure, there is 818 no need in IEEE 802.11-OCB to wait for the completion of association 819 and authentication procedures before exchanging data. IEEE 820 802.11-OCB enabled nodes use the wildcard BSSID (a value of all 1s) 821 and may start communicating as soon as they arrive on the 822 communication channel. 824 6.2. Capture in Normal Mode 826 The same IPv6 Router Advertisement packet described above (monitor 827 mode) is captured on the Host, in the Normal mode, and depicted 828 below. 830 Ethernet II Header 831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 832 | Destination... 833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 834 ...Destination | Source... 835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 836 ...Source | 837 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 | Type | 839 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 841 IPv6 Base Header 842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 |Version| Traffic Class | Flow Label | 844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 845 | Payload Length | Next Header | Hop Limit | 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 847 | | 848 + + 849 | | 850 + Source Address + 851 | | 852 + + 853 | | 854 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 855 | | 856 + + 857 | | 858 + Destination Address + 859 | | 860 + + 861 | | 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 864 Router Advertisement 865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 866 | Type | Code | Checksum | 867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 870 | Reachable Time | 871 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 872 | Retrans Timer | 873 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 874 | Options ... 875 +-+-+-+-+-+-+-+-+-+-+-+- 877 One notices that the Radiotap Header is not prepended, and that the 878 IEEE 802.11 Data Header and the Logical-Link Control Headers are not 879 present. On another hand, a new header named Ethernet II Header is 880 present. 882 The Destination and Source addresses in the Ethernet II header 883 contain the same values as the fields Receiver Address and 884 Transmitter Address present in the IEEE 802.11 Data Header in the 885 "monitor" mode capture. 887 The value of the Type field in the Ethernet II header is 0x86DD 888 (recognized as "IPv6"); this value is the same value as the value of 889 the field Type in the Logical-Link Control Header in the "monitor" 890 mode capture. 892 The knowledgeable experimenter will no doubt notice the similarity of 893 this Ethernet II Header with a capture in normal mode on a pure 894 Ethernet cable interface. 896 It may be interpreted that an Adaptation layer is inserted in a pure 897 IEEE 802.11 MAC packets in the air, before delivering to the 898 applications. In detail, this adaptation layer may consist in 899 elimination of the Radiotap, 802.11 and LLC headers and insertion of 900 the Ethernet II header. In this way, it can be stated that IPv6 runs 901 naturally straight over LLC over the 802.11-OCB MAC layer, as shown 902 by the use of the Type 0x86DD, and assuming an adaptation layer 903 (adapting 802.11 LLC/MAC to Ethernet II header). 905 7. Security Considerations 907 Any security mechanism at the IP layer or above that may be carried 908 out for the general case of IPv6 may also be carried out for IPv6 909 operating over 802.11-OCB. 911 802.11-OCB does not provide any cryptographic protection, because it 912 operates outside the context of a BSS (no Association Request/ 913 Response, no Challenge messages). Any attacker can therefore just 914 sit in the near range of vehicles, sniff the network (just set the 915 interface card's frequency to the proper range) and perform attacks 916 without needing to physically break any wall. Such a link is way 917 less protected than commonly used links (wired link or protected 918 802.11). 920 At the IP layer, IPsec can be used to protect unicast communications, 921 and SeND can be used for multicast communications. If no protection 922 is used by the IP layer, upper layers should be protected. 923 Otherwise, the end-user or system should be warned about the risks 924 they run. 926 As with all Ethernet and 802.11 interface identifiers, there may 927 exist privacy risks in the use of 802.11-OCB interface identifiers. 928 Moreover, in outdoors vehicular settings, the privacy risks are more 929 important than in indoors settings. New risks are induced by the 930 possibility of attacker sniffers deployed along routes which listen 931 for IP packets of vehicles passing by. For this reason, in the 932 802.11-OCB deployments, there is a strong necessity to use protection 933 tools such as dynamically changing MAC addresses. This may help 934 mitigate privacy risks to a certain level. On another hand, it may 935 have an impact in the way typical IPv6 address auto-configuration is 936 performed for vehicles (SLAAC would rely on MAC addresses amd would 937 hence dynamically change the affected IP address), in the way the 938 IPv6 Privacy addresses were used, and other effects. 940 8. IANA Considerations 942 9. Contributors 944 Romain Kuntz contributed extensively about IPv6 handovers between 945 links running outside the context of a BSS (802.11-OCB links). 947 Tim Leinmueller contributed the idea of the use of IPv6 over 948 802.11-OCB for distribution of certificates. 950 Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey 951 Voronov provided significant feedback on the experience of using IP 952 messages over 802.11-OCB in initial trials. 954 Michelle Wetterwald contributed extensively the MTU discussion, 955 offeried the ETSI ITS perspective, and reviewed other parts of the 956 document. 958 10. Acknowledgements 960 The authors would like to thank Witold Klaudel, Ryuji Wakikawa, 961 Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan 962 Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray 963 Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan, 964 Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne, 965 Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, and William 966 Whyte. Their valuable comments clarified certain issues and 967 generally helped to improve the document. 969 Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB 970 drivers for linux and described how. 972 For the multicast discussion, the authors would like to thank Owen 973 DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and 974 participants to discussions in network working groups. 976 The authours would like to thank participants to the Birds-of- 977 a-Feather "Intelligent Transportation Systems" meetings held at IETF 978 in 2016. 980 11. References 982 11.1. Normative References 984 [I-D.ietf-6man-default-iids] 985 Gont, F., Cooper, A., Thaler, D., and S. LIU, 986 "Recommendation on Stable IPv6 Interface Identifiers", 987 draft-ietf-6man-default-iids-16 (work in progress), 988 September 2016. 990 [I-D.ietf-6man-ug] 991 Carpenter, B. and S. Jiang, "Significance of IPv6 992 Interface Identifiers", draft-ietf-6man-ug-06 (work in 993 progress), December 2013. 995 [I-D.ietf-tsvwg-ieee-802-11] 996 Szigeti, T. and F. Baker, "DiffServ to IEEE 802.11 997 Mapping", draft-ietf-tsvwg-ieee-802-11-01 (work in 998 progress), November 2016. 1000 [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission 1001 of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, 1002 DOI 10.17487/RFC1042, February 1988, 1003 . 1005 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1006 Requirement Levels", BCP 14, RFC 2119, 1007 DOI 10.17487/RFC2119, March 1997, 1008 . 1010 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1011 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 1012 December 1998, . 1014 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1015 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1016 . 1018 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1019 "Randomness Requirements for Security", BCP 106, RFC 4086, 1020 DOI 10.17487/RFC4086, June 2005, 1021 . 1023 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1024 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1025 . 1027 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1028 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1029 DOI 10.17487/RFC4861, September 2007, 1030 . 1032 [RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing 1033 Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889, 1034 September 2010, . 1036 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1037 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1038 2011, . 1040 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1041 Bormann, "Neighbor Discovery Optimization for IPv6 over 1042 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1043 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1044 . 1046 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 1047 Considerations for IPv6 Address Generation Mechanisms", 1048 RFC 7721, DOI 10.17487/RFC7721, March 2016, 1049 . 1051 11.2. Informative References 1053 [etsi-302663-v1.2.1p-2013] 1054 "Intelligent Transport Systems (ITS); Access layer 1055 specification for Intelligent Transport Systems operating 1056 in the 5 GHz frequency band, 2013-07, document 1057 en_302663v010201p.pdf, document freely available at URL 1058 http://www.etsi.org/deliver/etsi_en/302600_302699/302663/ 1059 01.02.01_60/en_302663v010201p.pdf downloaded on October 1060 17th, 2013.". 1062 [etsi-draft-102492-2-v1.1.1-2006] 1063 "Electromagnetic compatibility and Radio spectrum Matters 1064 (ERM); Intelligent Transport Systems (ITS); Part 2: 1065 Technical characteristics for pan European harmonized 1066 communications equipment operating in the 5 GHz frequency 1067 range intended for road safety and traffic management, and 1068 for non-safety related ITS applications; System Reference 1069 Document, Draft ETSI TR 102 492-2 V1.1.1, 2006-07, 1070 document tr_10249202v010101p.pdf freely available at URL 1071 http://www.etsi.org/deliver/etsi_tr/102400_102499/ 1072 10249202/01.01.01_60/tr_10249202v010101p.pdf downloaded on 1073 October 18th, 2013.". 1075 [fcc-cc] "'Report and Order, Before the Federal Communications 1076 Commission Washington, D.C. 20554', FCC 03-324, Released 1077 on February 10, 2004, document FCC-03-324A1.pdf, document 1078 freely available at URL 1079 http://www.its.dot.gov/exit/fcc_edocs.htm downloaded on 1080 October 17th, 2013.". 1082 [fcc-cc-172-184] 1083 "'Memorandum Opinion and Order, Before the Federal 1084 Communications Commission Washington, D.C. 20554', FCC 1085 06-10, Released on July 26, 2006, document FCC- 1086 06-110A1.pdf, document freely available at URL 1087 http://hraunfoss.fcc.gov/edocs_public/attachmatch/ 1088 FCC-06-110A1.pdf downloaded on June 5th, 2014.". 1090 [I-D.jeong-ipwave-vehicular-networking-survey] 1091 Jeong, J., Cespedes, S., Benamar, N., and J. Haerri, 1092 "Survey on IP-based Vehicular Networking for Intelligent 1093 Transportation Systems", draft-jeong-ipwave-vehicular- 1094 networking-survey-00 (work in progress), October 2016. 1096 [I-D.perkins-intarea-multicast-ieee802] 1097 Perkins, C., Stanley, D., Kumari, W., and J. Zuniga, 1098 "Multicast Considerations over IEEE 802 Wireless Media", 1099 draft-perkins-intarea-multicast-ieee802-01 (work in 1100 progress), September 2016. 1102 [I-D.petrescu-its-scenarios-reqs] 1103 Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel, 1104 "Scenarios and Requirements for IP in Intelligent 1105 Transportation Systems", draft-petrescu-its-scenarios- 1106 reqs-03 (work in progress), October 2013. 1108 [ieee16094] 1109 "1609.2-2016 - IEEE Standard for Wireless Access in 1110 Vehicular Environments--Security Services for Applications 1111 and Management Messages; document freely available at URL 1112 https://standards.ieee.org/findstds/ 1113 standard/1609.2-2016.html retrieved on July 08th, 2016.". 1115 [ieee802.11-2012] 1116 "802.11-2012 - IEEE Standard for Information technology-- 1117 Telecommunications and information exchange between 1118 systems Local and metropolitan area networks--Specific 1119 requirements Part 11: Wireless LAN Medium Access Control 1120 (MAC) and Physical Layer (PHY) Specifications. Downloaded 1121 on October 17th, 2013, from IEEE Standards, document 1122 freely available at URL 1123 http://standards.ieee.org/findstds/ 1124 standard/802.11-2012.html retrieved on October 17th, 1125 2013.". 1127 [ieee802.11p-2010] 1128 "IEEE Std 802.11p(TM)-2010, IEEE Standard for Information 1129 Technology - Telecommunications and information exchange 1130 between systems - Local and metropolitan area networks - 1131 Specific requirements, Part 11: Wireless LAN Medium Access 1132 Control (MAC) and Physical Layer (PHY) Specifications, 1133 Amendment 6: Wireless Access in Vehicular Environments; 1134 document freely available at URL 1135 http://standards.ieee.org/getieee802/ 1136 download/802.11p-2010.pdf retrieved on September 20th, 1137 2013.". 1139 [ieeep1609.0-D2] 1140 "IEEE P1609.0/D2 Draft Guide for Wireless Access in 1141 Vehicular Environments (WAVE) Architecture. pdf, length 1142 879 Kb. Restrictions apply.". 1144 [ieeep1609.2-D17] 1145 "IEEE P1609.2(tm)/D17 Draft Standard for Wireless Access 1146 in Vehicular Environments - Security Services for 1147 Applications and Management Messages. pdf, length 2558 1148 Kb. Restrictions apply.". 1150 [ieeep1609.3-D9-2010] 1151 "IEEE P1609.3(tm)/D9, Draft Standard for Wireless Access 1152 in Vehicular Environments (WAVE) - Networking Services, 1153 August 2010. Authorized licensed use limited to: CEA. 1154 Downloaded on June 19, 2013 at 07:32:34 UTC from IEEE 1155 Xplore. Restrictions apply, document at persistent link 1156 http://ieeexplore.ieee.org/servlet/opac?punumber=5562705". 1158 [ieeep1609.4-D9-2010] 1159 "IEEE P1609.4(tm)/D9 Draft Standard for Wireless Access in 1160 Vehicular Environments (WAVE) - Multi-channel Operation. 1161 Authorized licensed use limited to: CEA. Downloaded on 1162 June 19, 2013 at 07:34:48 UTC from IEEE Xplore. 1163 Restrictions apply. Document at persistent link 1164 http://ieeexplore.ieee.org/servlet/opac?punumber=5551097". 1166 [TS103097] 1167 "Intelligent Transport Systems (ITS); Security; Security 1168 header and certificate formats; document freely available 1169 at URL http://www.etsi.org/deliver/ 1170 etsi_ts/103000_103099/103097/01.01.01_60/ 1171 ts_103097v010101p.pdf retrieved on July 08th, 2016.". 1173 Appendix A. ChangeLog 1175 The changes are listed in reverse chronological order, most recent 1176 changes appearing at the top of the list. 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 asymetry 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 Automotive networks require the unique representation of each of 1314 their node. Accordingly, a vehicle must be identified by at least 1315 one unique ID. The current specification at ETSI and at IEEE 1609 1316 identifies a vehicle by its MAC address uniquely obtained from the 1317 802.11-OCB NIC. 1319 A MAC address uniquely obtained from a IEEE 802.11-OCB NIC 1320 implicitely generates multiple vehicle IDs in case of multiple 1321 802.11-OCB NICs. A mechanims to uniquely identify a vehicle 1322 irrespectively to the different NICs and/or technologies is required. 1324 C.2. Reliability Requirements 1326 The dynamically changing topology, short connectivity, mobile 1327 transmitter and receivers, different antenna heights, and many-to- 1328 many communication types, make IEEE 802.11-OCB links significantly 1329 different from other IEEE 802.11 links. Any IPv6 mechanism operating 1330 on IEEE 802.11-OCB link MUST support strong link asymetry, spatio- 1331 temporal link quality, fast address resolution and transmission. 1333 IEEE 802.11-OCB strongly differs from other 802.11 systems to operate 1334 outside of the context of a Basic Service Set. This means in 1335 practice that IEEE 802.11-OCB does not rely on a Base Station for all 1336 Basic Service Set management. In particular, IEEE 802.11-OCB SHALL 1337 NOT use beacons. Any IPv6 mechanism requiring L2 services from IEEE 1338 802.11 beacons MUST support an alternative service. 1340 Channel scanning being disabled, IPv6 over IEEE 802.11-OCB MUST 1341 implement a mechanism for transmitter and receiver to converge to a 1342 common channel. 1344 Authentication not being possible, IPv6 over IEEE 802.11-OCB MUST 1345 implement an distributed mechanism to authenticate transmitters and 1346 receivers without the support of a DHCP server. 1348 Time synchronization not being available, IPv6 over IEEE 802.11-OCB 1349 MUST implement a higher layer mechanism for time synchronization 1350 between transmitters and receivers without the support of a NTP 1351 server. 1353 The IEEE 802.11-OCB link being asymetic, IPv6 over IEEE 802.11-OCB 1354 MUST disable management mechanisms requesting acknowledgements or 1355 replies. 1357 The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE 1358 802.11-OCB MUST implement fast IPv6 mobility management mechanisms. 1360 C.3. Multiple interfaces 1362 There are considerations for 2 or more IEEE 802.11-OCB interface 1363 cards per vehicle. For each vehicle taking part in road traffic, one 1364 IEEE 802.11-OCB interface card MUST be fully allocated for Non IP 1365 safety-critical communication. Any other IEEE 802.11-OCB may be used 1366 for other type of traffic. 1368 The mode of operation of these other wireless interfaces is not 1369 clearly defined yet. One possibility is to consider each card as an 1370 independent network interface, with a specific MAC Address and a set 1371 of IPv6 addresses. Another possibility is to consider the set of 1372 these wireless interfaces as a single network interface (not 1373 including the IEEE 802.11-OCB interface used by Non IP safety 1374 critical communications). This will require specific logic to 1375 ensure, for example, that packets meant for a vehicle in front are 1376 actually sent by the radio in the front, or that multiple copies of 1377 the same packet received by multiple interfaces are treated as a 1378 single packet. Treating each wireless interface as a separate 1379 network interface pushes such issues to the application layer. 1381 If Mobile IPv6 with NEMO extensions is used, then the MCoA RFC5648 1382 technology is relevant for Mobile Routers with multiple interfaces, 1383 deployed in vehicles. 1385 The privacy requirements of [] imply that if these multiple 1386 interfaces are represented by many network interface, a single 1387 renumbering event SHALL cause renumbering of all these interfaces. 1389 If one MAC changed and another stayed constant, external observers 1390 would be able to correlate old and new values, and the privacy 1391 benefits of randomization would be lost. 1393 The privacy requirements of Non IP safety-critical communications 1394 imply that if a change of pseudonyme occurs, renumbering of all other 1395 interfaces SHALL also occur. 1397 C.4. MAC Address Generation 1399 When designing the IPv6 over 802.11-OCB address mapping, we will 1400 assume that the MAC Addresses will change during well defined 1401 "renumbering events". The 48 bits randomized MAC addresses will have 1402 the following characteristics: 1404 o Bit "Local/Global" set to "locally admninistered". 1406 o Bit "Unicast/Multicast" set to "Unicast". 1408 o 46 remaining bits set to a random value, using a random number 1409 generator that meets the requirements of [RFC4086]. 1411 The way to meet the randomization requirements is to retain 46 bits 1412 from the output of a strong hash function, such as SHA256, taking as 1413 input a 256 bit local secret, the "nominal" MAC Address of the 1414 interface, and a representation of the date and time of the 1415 renumbering event. 1417 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode 1419 For information, at the time of writing, this is the list of IEEE 1420 802.11 messages that may be transmitted in OCB mode, i.e. when 1421 dot11OCBActivated is true in a STA: 1423 o The STA may send management frames of subtype Action and, if the 1424 STA maintains a TSF Timer, subtype Timing Advertisement; 1426 o The STA may send control frames, except those of subtype PS-Poll, 1427 CF-End, and CF-End plus CFAck; 1429 o The STA may send data frames of subtype Data, Null, QoS Data, and 1430 QoS Null. 1432 Authors' Addresses 1433 Alexandre Petrescu 1434 CEA, LIST 1435 CEA Saclay 1436 Gif-sur-Yvette , Ile-de-France 91190 1437 France 1439 Phone: +33169089223 1440 Email: Alexandre.Petrescu@cea.fr 1442 Nabil Benamar 1443 Moulay Ismail University 1444 Morocco 1446 Phone: +212670832236 1447 Email: benamar73@gmail.com 1449 Jerome Haerri 1450 Eurecom 1451 Sophia-Antipolis 06904 1452 France 1454 Phone: +33493008134 1455 Email: Jerome.Haerri@eurecom.fr 1457 Christian Huitema 1458 Friday Harbor, WA 98250 1459 U.S.A. 1461 Email: huitema@huitema.net 1463 Jong-Hyouk Lee 1464 Sangmyung University 1465 31, Sangmyeongdae-gil, Dongnam-gu 1466 Cheonan 31066 1467 Republic of Korea 1469 Email: jonghyouk@smu.ac.kr 1471 Thierry Ernst 1472 YoGoKo 1473 France 1475 Email: thierry.ernst@yogoko.fr 1476 Tony Li 1477 Peloton Technology 1478 1060 La Avenida St. 1479 Mountain View, California 94043 1480 United States 1482 Phone: +16503957356 1483 Email: tony.li@tony.li