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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: August 24, 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 February 20, 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-01.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 August 24, 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 802.11p 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 802.11p link . . . . 15 91 6.1. Capture in Monitor Mode . . . . . . . . . . . . . . . . . 15 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 . . . . . . . . . . . . . . . 28 104 C.1. Vehicle ID . . . . . . . . . . . . . . . . . . . . . . . 28 105 C.2. Reliability Requirements . . . . . . . . . . . . . . . . 29 106 C.3. Multiple interfaces . . . . . . . . . . . . . . . . . . . 29 107 C.4. MAC Address Generation . . . . . . . . . . . . . . . . . 30 108 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, and vice-versa. 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 We briefly introduce the vehicular communication scenarios where IEEE 180 802.11-OCB links are used. This is followed by a description of 181 differences in specification terms, between 802.11 OCB and 182 802.11a/b/g/n (and the same differences expressed in terms of 183 requirements to software implementation are listed in Appendix B.) 185 The document then concentrates on the parameters of layering IP over 186 802.11 OCB as over Ethernet: MTU, Frame Format, Interface Identifier, 187 Address Mapping, State-less Address Auto-configuration. The values 188 of these parameters are precisely the same as IPv6 over Ethernet 189 [RFC2464]: the recommended value of MTU to be 1500 octets, the Frame 190 Format containing the Type 0x86DD, the rules for forming an Interface 191 Identifier, the Address Mapping mechanism and the Stateless Address 192 Auto-Configuration. 194 As an example, these characteristics of layering IPv6 straight over 195 LLC over 802.11 OCB MAC are illustrated by dissecting an IPv6 packet 196 captured over a 802.11 OCB link; this is described in the section 197 Section 6. 199 A couple of points can be considered as different, although they are 200 not required in order to have a working implementation of IPv6-over- 201 802.11-OCB. These points are consequences of the OCB operation which 202 is particular to 802.11 OCB (Outside the Context of a BSS). First, 203 the handovers between OCB links need specific behaviour for IP Router 204 Advertisements, or otherwise 802.11 OCB's Time Advertisement, or of 205 higher layer messages such as the 'Basic Safety Message' (in the US) 206 or the 'Cooperative Awareness Message' (in the EU) or the 'WAVE 207 Routing Advertisement'; second, the IP security mechanisms are 208 necessary, since OCB means that 802.11 is stripped of all 802.11 209 link-layer security; a small additional security aspect which is 210 shared between 802.11 OCB and other 802.11 links is the privacy 211 concerns related to the address formation mechanisms. 213 In the published literature, many documents describe aspects related 214 to running IPv6 over 802.11 OCB: 215 [I-D.jeong-ipwave-vehicular-networking-survey]. 217 2. Terminology 219 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 220 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 221 document are to be interpreted as described in RFC 2119 [RFC2119]. 223 RSU: Road Side Unit. An IP router equipped with, or connected to, at 224 least one interface that is 802.11 and that is an interface that 225 operates in OCB mode. 227 OCB: outside the context of a basic service set (BSS): A mode of 228 operation in which a STA is not a member of a BSS and does not 229 utilize IEEE Std 802.11 authentication, association, or data 230 confidentiality. 232 802.11-OCB: text in document IEEE 802.11-2012 that is flagged by 233 "dot11OCBActivated". This means: IEEE 802.11e for quality of 234 service; 802.11j-2004 for half-clocked operations; and 802.11p for 235 operation in the 5.9 GHz band and in mode OCB. 237 3. Communication Scenarios where IEEE 802.11 OCB Links are Used 239 The IEEE 802.11 OCB Networks are used for vehicular communications, 240 as 'Wireless Access in Vehicular Environments'. The IP communication 241 scenarios for these environments have been described in several 242 documents, among which we refer the reader to one recently updated 243 [I-D.petrescu-its-scenarios-reqs], about scenarios and requirements 244 for IP in Intelligent Transportation Systems. 246 4. Aspects introduced by the OCB mode to 802.11 248 In the IEEE 802.11 OCB mode, all nodes in the wireless range can 249 directly communicate with each other without authentication/ 250 association procedures. Briefly, the IEEE 802.11 OCB mode has the 251 following properties: 253 o The use by each node of a 'wildcard' BSSID (i.e., each bit of the 254 BSSID is set to 1) 256 o No Beacons transmitted 258 o No authentication required 260 o No association needed 262 o No encryption provided 264 o Flag dot11OCBActivated set to true 266 The following message exchange diagram illustrates a comparison 267 between traditional 802.11 and 802.11 in OCB mode. The 'Data' 268 messages can be IP messages such as the messages used in Stateless or 269 Stateful Address Auto-Configuration, or other IP messages. Other 270 802.11 management and control frames (non IP) may be transmitted, as 271 specified in the 802.11 standard. For information, the names of 272 these messages as currently specified by the 802.11 standard are 273 listed in Appendix D. 275 STA AP STA1 STA2 276 | | | | 277 |<------ Beacon -------| |<------ Data -------->| 278 | | |<------ Data -------->| 279 |---- Probe Req. ----->| |<------ Data -------->| 280 |<--- Probe Res. ------| |<------ Data -------->| 281 | | |<------ Data -------->| 282 |---- Auth Req. ------>| |<------ Data -------->| 283 |<--- Auth Res. -------| |<------ Data -------->| 284 | | |<------ Data -------->| 285 |---- Asso Req. ------>| |<------ Data -------->| 286 |<--- Asso Res. -------| |<------ Data -------->| 287 | | |<------ Data -------->| 288 |------- Data -------->| |<------ Data -------->| 289 |------- Data -------->| |<------ Data -------->| 291 (a) Traditional IEEE 802.11 (b) IEEE 802.11 OCB mode 293 The link 802.11 OCB was specified in IEEE Std 802.11p(TM)-2010 294 [ieee802.11p-2010] as an amendment to the 802.11 specifications, 295 titled "Amendment 6: Wireless Access in Vehicular Environments". 296 Since then, these 802.11p amendments have been included in IEEE 297 802.11(TM)-2012 [ieee802.11-2012], titled "IEEE Standard for 298 Information technology--Telecommunications and information exchange 299 between systems Local and metropolitan area networks--Specific 300 requirements Part 11: Wireless LAN Medium Access Control (MAC) and 301 Physical Layer (PHY) Specifications"; the modifications are diffused 302 throughout various sections (e.g. 802.11p's Time Advertisement 303 message is described in section 'Frame formats', and the operation 304 outside the context of a BSS described in section 'MLME'). 306 In document 802.11-2012, specifically anything referring 307 "OCBActivated", or "outside the context of a basic service set" is 308 actually referring to the 802.11p aspects introduced to 802.11. Note 309 in earlier 802.11p documents the term "OCBEnabled" was used instead. 311 In order to delineate the aspects introduced by 802.11 OCB to 802.11, 312 we refer to the earlier [ieee802.11p-2010]. The amendment is 313 concerned with vehicular communications, where the wireless link is 314 similar to that of Wireless LAN (using a PHY layer specified by 315 802.11a/b/g/n), but which needs to cope with the high mobility factor 316 inherent in scenarios of communications between moving vehicles, and 317 between vehicles and fixed infrastructure deployed along roads. 318 While 'p' is a letter just like 'a, b, g' and 'n' are, 'p' is 319 concerned more with MAC modifications, and a little with PHY 320 modifications; the others are mainly about PHY modifications. It is 321 possible in practice to combine a 'p' MAC with an 'a' PHY by 322 operating outside the context of a BSS with OFDM at 5.4GHz. 324 The 802.11 OCB links are specified to be compatible as much as 325 possible with the behaviour of 802.11a/b/g/n and future generation 326 IEEE WLAN links. From the IP perspective, an 802.11 OCB MAC layer 327 offers practically the same interface to IP as the WiFi and Ethernet 328 layers do (802.11a/b/g/n and 802.3). 330 To support this similarity statement (IPv6 is layered on top of LLC 331 on top of 802.11 OCB similarly as on top of LLC on top of 332 802.11a/b/g/n, and as on top of LLC on top of 802.3) it is useful to 333 analyze the differences between 802.11 OCB and 802.11 specifications. 334 Whereas the 802.11p amendment specifies relatively complex and 335 numerous changes to the MAC layer (and very little to the PHY layer), 336 we note there are only a few characteristics which may be important 337 for an implementation transmitting IPv6 packets on 802.11 OCB links. 339 In the list below, the only 802.11 OCB fundamental points which 340 influence IPv6 are the OCB operation and the 12Mbit/s maximum which 341 may be afforded by the IPv6 applications. 343 o Operation Outside the Context of a BSS (OCB): the 802.11p links 344 are operated without a Basic Service Set (BSS). This means that 345 the messages Beacon, Association Request/Response, Authentication 346 Request/Response, and similar, are not used. The used identifier 347 of BSS (BSSID) has a hexadecimal value always ff:ff:ff:ff:ff:ff 348 (48 '1' bits, or the 'wildcard' BSSID), as opposed to an arbitrary 349 BSSID value set by administrator (e.g. 'My-Home-AccessPoint'). 350 The OCB operation - namely the lack of beacon-based scanning and 351 lack of authentication - has a potentially strong impact on the 352 use of the Mobile IPv6 protocol and on the protocols for IP layer 353 security. 355 o Timing Advertisement: is a new message defined in 802.11p, which 356 does not exist in 802.11a/b/g/n. This message is used by stations 357 to inform other stations about the value of time. It is similar 358 to the time as delivered by a GNSS system (Galileo, GPS, ...) or 359 by a cellular system. This message is optional for 360 implementation. At the date of writing, an experienced reviewer 361 considers that currently no field testing has used this message. 362 Another implementor considers this feature implemented in an 363 initial manner. In the future, it is speculated that this message 364 may be useful for very simple devices which may not have their own 365 hardware source of time (Galileo, GPS, cellular network), or by 366 vehicular devices situated in areas not covered by such network 367 (in tunnels, underground, outdoors but shaded by foliage or 368 buildings, in remote areas, etc.) 370 o Frequency range: this is a characteristic of the PHY layer, with 371 almost no impact to the interface between MAC and IP. However, it 372 is worth considering that the frequency range is regulated by a 373 regional authority (ARCEP, ETSI, FCC, etc.); as part of the 374 regulation process, specific applications are associated with 375 specific frequency ranges. In the case of 802.11p, the regulator 376 associates a set of frequency ranges, or slots within a band, to 377 the use of applications of vehicular communications, in a band 378 known as "5.9GHz". This band is "5.9GHz" which is different from 379 the bands "2.4GHz" or "5GHz" used by Wireless LAN. However, as 380 with Wireless LAN, the operation of 802.11p in "5.9GHz" bands is 381 exempt from owning a license in EU (in US the 5.9GHz is a licensed 382 band of spectrum; for the the fixed infrastructure an explicit FCC 383 autorization is required; for an onboard device a 'licensed-by- 384 rule' concept applies: rule certification conformity is required); 385 however technical conditions are different than those of the bands 386 "2.4GHz" or "5GHz". On one hand, the allowed power levels, and 387 implicitly the maximum allowed distance between vehicles, is of 388 33dBm for 802.11p (in Europe), compared to 20 dBm for Wireless LAN 389 802.11a/b/g/n; this leads to a maximum distance of approximately 390 1km, compared to approximately 50m. On the hand, specific 391 conditions related to congestion avoidance, jamming avoidance, and 392 radar detection are imposed on the use of DSRC (in US) and on the 393 use of frequencies for Intelligent Transportation Systems (in EU), 394 compared to Wireless LAN (802.11a/b/g/n). 396 o Prohibition of IPv6 on some channels relevant for the PHY of IEEE 397 802.11-OCB, as opposed to IPv6 not being prohibited on any channel 398 on which 802.11a/b/g/n runs; at the time of writing, this 399 prohibition is explicit in IEEE 1609 documents. 401 o 'Half-rate' encoding: as the frequency range, this parameter is 402 related to PHY, and thus has not much impact on the interface 403 between the IP layer and the MAC layer. 405 o In vehicular communications using 802.11p links, there are strong 406 privacy concerns with respect to addressing. While the 802.11p 407 standard does not specify anything in particular with respect to 408 MAC addresses, in these settings there exists a strong need for 409 dynamic change of these addresses (as opposed to the non-vehicular 410 settings - real wall protection - where fixed MAC addresses do not 411 currently pose some privacy risks). This is further described in 412 section Section 7. A relevant function is described in IEEE 413 1609.3, clause 5.5.1 and IEEE 1609.4, clause 6.7. 415 Other aspects particular to 802.11p which are also particular to 416 802.11 (e.g. the 'hidden node' operation) may have an influence on 417 the use of transmission of IPv6 packets on 802.11p networks. The 418 subnet structure which may be assumed in 802.11p networks is strongly 419 influenced by the mobility of vehicles. 421 5. Layering of IPv6 over 802.11p as over Ethernet 423 5.1. Maximum Transmission Unit (MTU) 425 The default MTU for IP packets on 802.11p is 1500 octets. It is the 426 same value as IPv6 packets on Ethernet links, as specified in 427 [RFC2464]. This value of the MTU respects the recommendation that 428 every link in the Internet must have a minimum MTU of 1280 octets 429 (stated in [RFC2460], and the recommendations therein, especially 430 with respect to fragmentation). If IPv6 packets of size larger than 431 1500 bytes are sent on an 802.11-OCB interface then the IP stack will 432 fragment. In case there are IP fragments, the field "Sequence 433 number" of the 802.11 Data header containing the IP fragment field is 434 increased. 436 Non-IP packets such as WAVE Short Message Protocol (WSMP) can be 437 delivered on 802.11-OCB links. Specifications of these packets are 438 out of scope of this document, and do not impose any limit on the MTU 439 size, allowing an arbitrary number of 'containers'. Non-IP packets 440 such as ETSI 'geonet' packets have an MTU of 1492 bytes. 442 The Equivalent Transmit Time on Channel is a concept that may be used 443 as an alternative to the MTU concept. A rate of transmission may be 444 specified as well. The ETTC, rate and MTU may be in direct 445 relationship. 447 5.2. Frame Format 449 IP packets are transmitted over 802.11p as standard Ethernet packets. 450 As with all 802.11 frames, an Ethernet adaptation layer is used with 451 802.11p as well. This Ethernet Adaptation Layer 802.11-to-Ethernet 452 is described in Section 5.2.1. The Ethernet Type code (EtherType) 453 for IPv6 is 0x86DD (hexadecimal 86DD, or otherwise #86DD). 455 The Frame format for transmitting IPv6 on 802.11p networks is the 456 same as transmitting IPv6 on Ethernet networks, and is described in 457 section 3 of [RFC2464]. The frame format for transmitting IPv6 458 packets over Ethernet is illustrated below: 460 0 1 461 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 | Destination | 464 +- -+ 465 | Ethernet | 466 +- -+ 467 | Address | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 | Source | 470 +- -+ 471 | Ethernet | 472 +- -+ 473 | Address | 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 |1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1| 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 | IPv6 | 478 +- -+ 479 | header | 480 +- -+ 481 | and | 482 +- -+ 483 / payload ... / 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 (Each tic mark represents one bit.) 487 5.2.1. Ethernet Adaptation Layer 489 In general, an 'adaptation' layer is inserted between a MAC layer and 490 the Networking layer. This is used to transform some parameters 491 between their form expected by the IP stack and the form provided by 492 the MAC layer. For example, an 802.15.4 adaptation layer may perform 493 fragmentation and reassembly operations on a MAC whose maximum Packet 494 Data Unit size is smaller than the minimum MTU recognized by the IPv6 495 Networking layer. Other examples involve link-layer address 496 transformation, packet header insertion/removal, and so on. 498 An Ethernet Adaptation Layer makes an 802.11 MAC look to IP 499 Networking layer as a more traditional Ethernet layer. At reception, 500 this layer takes as input the IEEE 802.11 Data Header and the 501 Logical-Link Layer Control Header and produces an Ethernet II Header. 502 At sending, the reverse operation is performed. 504 +--------------------+-------------+-------------+---------+ 505 | 802.11 Data Header | LLC Header | IPv6 Header | Payload | 506 +--------------------+-------------+-------------+---------+ 507 ^ 508 | 509 802.11-to-Ethernet Adaptation Layer 510 | 511 v 513 +---------------------+-------------+---------+ 514 | Ethernet II Header | IPv6 Header | Payload | 515 +---------------------+-------------+---------+ 517 The Receiver and Transmitter Address fields in the 802.11 Data Header 518 contain the same values as the Destination and the Source Address 519 fields in the Ethernet II Header, respectively. The value of the 520 Type field in the LLC Header is the same as the value of the Type 521 field in the Ethernet II Header. 523 When the MTU value is smaller than the size of the IP packet to be 524 sent, the IP layer fragments the packet into multiple IP fragments. 525 During this operation, the "Sequence number" field of the 802.11 Data 526 Header is increased. 528 In OCB mode, IPv6 packets can be transmitted either as "IEEE 802.11 529 Data" or alternatively as "IEEE 802.11 QoS Data", as illustrated in 530 the following figure: 532 +--------------------+-------------+-------------+---------+ 533 | 802.11 Data Header | LLC Header | IPv6 Header | Payload | 534 +--------------------+-------------+-------------+---------+ 536 or 538 +--------------------+-------------+-------------+---------+ 539 | 802.11 QoS Data Hdr| LLC Header | IPv6 Header | Payload | 540 +--------------------+-------------+-------------+---------+ 542 The distinction between the two formats is given by the value of the 543 field "Type/Subtype". The value of the field "Type/Subtype" in the 544 802.11 Data header is 0x0020. The value of the field "Type/Subtype" 545 in the 802.11 QoS header is 0x0028. 547 The mapping between qos-related fields in the IPv6 header (e.g. 548 "Traffic Class", "Flow label") and fields in the "802.11 QoS Data 549 Header" (e.g. "QoS Control") are not specified in this document. 550 Guidance for a potential mapping is provided in 551 [I-D.ietf-tsvwg-ieee-802-11], although it is not specific to OCB 552 mode. 554 5.3. Link-Local Addresses 556 The link-local address of an 802.11p interface is formed in the same 557 manner as on an Ethernet interface. This manner is described in 558 section 5 of [RFC2464]. 560 5.4. Address Mapping 562 For unicast as for multicast, there is no change from the unicast and 563 multicast address mapping format of Ethernet interfaces, as defined 564 by sections 6 and 7 of [RFC2464]. 566 5.4.1. Address Mapping -- Unicast 568 5.4.2. Address Mapping -- Multicast 570 IPv6 protocols often make use of IPv6 multicast addresses in the 571 destination field of IPv6 headers. For example, an ICMPv6 link- 572 scoped Neighbor Advertisement is sent to the IPv6 address ff02::1 573 denoted "all-nodes" address. When transmitting these packets on 574 802.11-OCB links it is necessary to map the IPv6 address to a MAC 575 address. 577 The same mapping requirement applies to the link-scoped multicast 578 addresses of other IPv6 protocols as well. In DHCPv6, the 579 "All_DHCP_Servers" IPv6 multicast address ff02::1:2, and in OSPF the 580 "All_SPF_Routers" IPv6 multicast address ff02::5, need to be mapped 581 on a multicast MAC address. 583 An IPv6 packet with a multicast destination address DST, consisting 584 of the sixteen octets DST[1] through DST[16], is transmitted to the 585 IEEE 802.11-OCB MAC multicast address whose first two octets are the 586 value 0x3333 and whose last four octets are the last four octets of 587 DST. 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 |0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1| 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 | DST[13] | DST[14] | 593 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 | DST[15] | DST[16] | 595 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 597 A Group ID TBD of length 112bits may be requested from IANA; this 598 Group ID signifies "All 80211OCB Interfaces Address". Only the least 599 32 significant bits of this "All 80211OCB Interfaces Address" will be 600 mapped to and from a MAC multicast address. 602 Transmitting IPv6 packets to multicast destinations over 802.11 links 603 proved to have some performance issues 604 [I-D.perkins-intarea-multicast-ieee802]. These issues may be 605 exacerbated in OCB mode. Solutions for these problems should 606 consider the OCB mode of operation. 608 5.5. Stateless Autoconfiguration 610 The Interface Identifier for an 802.11p interface is formed using the 611 same rules as the Interface Identifier for an Ethernet interface; 612 this is described in section 4 of [RFC2464]. No changes are needed, 613 but some care must be taken when considering the use of the SLAAC 614 procedure. 616 The bits in the the interface identifier have no generic meaning and 617 the identifier should be treated as an opaque value. The bits 618 'Universal' and 'Group' in the identifier of an 802.11p interface are 619 significant, as this is a IEEE link-layer address. The details of 620 this significance are described in [I-D.ietf-6man-ug]. 622 As with all Ethernet and 802.11 interface identifiers ([RFC7721]), 623 the identifier of an 802.11p interface may involve privacy risks. A 624 vehicle embarking an On-Board Unit whose egress interface is 802.11p 625 may expose itself to eavesdropping and subsequent correlation of 626 data; this may reveal data considered private by the vehicle owner. 628 If stable Interface Identifiers are needed in order to form IPv6 629 addresses on 802.11-OCB links, it is recommended to follow the 630 recommendation in [I-D.ietf-6man-default-iids]. 632 5.6. Subnet Structure 634 The 802.11 networks in OCB mode may be considered as 'ad-hoc' 635 networks. The addressing model for such networks is described in 636 [RFC5889]. 638 6. Example IPv6 Packet captured over a IEEE 802.11p link 640 We remind that a main goal of this document is to make the case that 641 IPv6 works fine over 802.11p networks. Consequently, this section is 642 an illustration of this concept and thus can help the implementer 643 when it comes to running IPv6 over IEEE 802.11p. By way of example 644 we show that there is no modification in the headers when transmitted 645 over 802.11p networks - they are transmitted like any other 802.11 646 and Ethernet packets. 648 We describe an experiment of capturing an IPv6 packet on an 802.11p 649 link. In this experiment, the packet is an IPv6 Router 650 Advertisement. This packet is emitted by a Router on its 802.11p 651 interface. The packet is captured on the Host, using a network 652 protocol analyzer (e.g. Wireshark); the capture is performed in two 653 different modes: direct mode and 'monitor' mode. The topology used 654 during the capture is depicted below. 656 +--------+ +-------+ 657 | | 802.11-OCB Link | | 658 ---| Router |--------------------------------| Host | 659 | | | | 660 +--------+ +-------+ 662 During several capture operations running from a few moments to 663 several hours, no message relevant to the BSSID contexts were 664 captured (no Association Request/Response, Authentication Req/Resp, 665 Beacon). This shows that the operation of 802.11p is outside the 666 context of a BSSID. 668 Overall, the captured message is identical with a capture of an IPv6 669 packet emitted on a 802.11b interface. The contents are precisely 670 similar. 672 6.1. Capture in Monitor Mode 674 The IPv6 RA packet captured in monitor mode is illustrated below. 675 The radio tap header provides more flexibility for reporting the 676 characteristics of frames. The Radiotap Header is prepended by this 677 particular stack and operating system on the Host machine to the RA 678 packet received from the network (the Radiotap Header is not present 679 on the air). The implementation-dependent Radiotap Header is useful 680 for piggybacking PHY information from the chip's registers as data in 681 a packet understandable by userland applications using Socket 682 interfaces (the PHY interface can be, for example: power levels, data 683 rate, ratio of signal to noise). 685 The packet present on the air is formed by IEEE 802.11 Data Header, 686 Logical Link Control Header, IPv6 Base Header and ICMPv6 Header. 688 Radiotap Header v0 689 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 690 |Header Revision| Header Pad | Header length | 691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 692 | Present flags | 693 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 694 | Data Rate | Pad | 695 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 697 IEEE 802.11 Data Header 698 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 699 | Type/Subtype and Frame Ctrl | Duration | 700 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 701 | Receiver Address... 702 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 703 ... Receiver Address | Transmitter Address... 704 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 705 ... Transmitter Address | 706 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 707 | BSS Id... 708 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 709 ... BSS Id | Frag Number and Seq Number | 710 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 712 Logical-Link Control Header 713 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 714 | DSAP |I| SSAP |C| Control field | Org. code... 715 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 716 ... Organizational Code | Type | 717 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 719 IPv6 Base Header 720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 721 |Version| Traffic Class | Flow Label | 722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 723 | Payload Length | Next Header | Hop Limit | 724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 | | 726 + + 727 | | 728 + Source Address + 729 | | 730 + + 731 | | 732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 | | 734 + + 735 | | 736 + Destination Address + 737 | | 738 + + 739 | | 740 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 742 Router Advertisement 743 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 744 | Type | Code | Checksum | 745 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 746 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 748 | Reachable Time | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 750 | Retrans Timer | 751 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 752 | Options ... 753 +-+-+-+-+-+-+-+-+-+-+-+- 755 The value of the Data Rate field in the Radiotap header is set to 6 756 Mb/s. This indicates the rate at which this RA was received. 758 The value of the Transmitter address in the IEEE 802.11 Data Header 759 is set to a 48bit value. The value of the destination address is 760 33:33:00:00:00:1 (all-nodes multicast address). The value of the BSS 761 Id field is ff:ff:ff:ff:ff:ff, which is recognized by the network 762 protocol analyzer as being "broadcast". The Fragment number and 763 sequence number fields are together set to 0x90C6. 765 The value of the Organization Code field in the Logical-Link Control 766 Header is set to 0x0, recognized as "Encapsulated Ethernet". The 767 value of the Type field is 0x86DD (hexadecimal 86DD, or otherwise 768 #86DD), recognized as "IPv6". 770 A Router Advertisement is periodically sent by the router to 771 multicast group address ff02::1. It is an icmp packet type 134. The 772 IPv6 Neighbor Discovery's Router Advertisement message contains an 773 8-bit field reserved for single-bit flags, as described in [RFC4861]. 775 The IPv6 header contains the link local address of the router 776 (source) configured via EUI-64 algorithm, and destination address set 777 to ff02::1. Recent versions of network protocol analyzers (e.g. 778 Wireshark) provide additional informations for an IP address, if a 779 geolocalization database is present. In this example, the 780 geolocalization database is absent, and the "GeoIP" information is 781 set to unknown for both source and destination addresses (although 782 the IPv6 source and destination addresses are set to useful values). 783 This "GeoIP" can be a useful information to look up the city, 784 country, AS number, and other information for an IP address. 786 The Ethernet Type field in the logical-link control header is set to 787 0x86dd which indicates that the frame transports an IPv6 packet. In 788 the IEEE 802.11 data, the destination address is 33:33:00:00:00:01 789 which is he corresponding multicast MAC address. The BSS id is a 790 broadcast address of ff:ff:ff:ff:ff:ff. Due to the short link 791 duration between vehicles and the roadside infrastructure, there is 792 no need in IEEE 802.11p to wait for the completion of association and 793 authentication procedures before exchanging data. IEEE 802.11p 794 enabled nodes use the wildcard BSSID (a value of all 1s) and may 795 start communicating as soon as they arrive on the communication 796 channel. 798 6.2. Capture in Normal Mode 800 The same IPv6 Router Advertisement packet described above (monitor 801 mode) is captured on the Host, in the Normal mode, and depicted 802 below. 804 Ethernet II Header 805 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 806 | Destination... 807 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 808 ...Destination | Source... 809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 810 ...Source | 811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 812 | Type | 813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 815 IPv6 Base Header 816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 817 |Version| Traffic Class | Flow Label | 818 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 819 | Payload Length | Next Header | Hop Limit | 820 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 821 | | 822 + + 823 | | 824 + Source Address + 825 | | 826 + + 827 | | 828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 829 | | 830 + + 831 | | 832 + Destination Address + 833 | | 834 + + 835 | | 836 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 Router Advertisement 839 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 840 | Type | Code | Checksum | 841 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 842 | Cur Hop Limit |M|O| Reserved | Router Lifetime | 843 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 844 | Reachable Time | 845 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 846 | Retrans Timer | 847 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 848 | Options ... 849 +-+-+-+-+-+-+-+-+-+-+-+- 851 One notices that the Radiotap Header is not prepended, and that the 852 IEEE 802.11 Data Header and the Logical-Link Control Headers are not 853 present. On another hand, a new header named Ethernet II Header is 854 present. 856 The Destination and Source addresses in the Ethernet II header 857 contain the same values as the fields Receiver Address and 858 Transmitter Address present in the IEEE 802.11 Data Header in the 859 "monitor" mode capture. 861 The value of the Type field in the Ethernet II header is 0x86DD 862 (recognized as "IPv6"); this value is the same value as the value of 863 the field Type in the Logical-Link Control Header in the "monitor" 864 mode capture. 866 The knowledgeable experimenter will no doubt notice the similarity of 867 this Ethernet II Header with a capture in normal mode on a pure 868 Ethernet cable interface. 870 It may be interpreted that an Adaptation layer is inserted in a pure 871 IEEE 802.11 MAC packets in the air, before delivering to the 872 applications. In detail, this adaptation layer may consist in 873 elimination of the Radiotap, 802.11 and LLC headers and insertion of 874 the Ethernet II header. In this way, it can be stated that IPv6 runs 875 naturally straight over LLC over the 802.11p MAC layer, as shown by 876 the use of the Type 0x86DD, and assuming an adaptation layer 877 (adapting 802.11 LLC/MAC to Ethernet II header). 879 7. Security Considerations 881 Any security mechanism at the IP layer or above that may be carried 882 out for the general case of IPv6 may also be carried out for IPv6 883 operating over 802.11-OCB. 885 802.11p does not provide any cryptographic protection, because it 886 operates outside the context of a BSS (no Association Request/ 887 Response, no Challenge messages). Any attacker can therefore just 888 sit in the near range of vehicles, sniff the network (just set the 889 interface card's frequency to the proper range) and perform attacks 890 without needing to physically break any wall. Such a link is way 891 less protected than commonly used links (wired link or protected 892 802.11). 894 At the IP layer, IPsec can be used to protect unicast communications, 895 and SeND can be used for multicast communications. If no protection 896 is used by the IP layer, upper layers should be protected. 897 Otherwise, the end-user or system should be warned about the risks 898 they run. 900 As with all Ethernet and 802.11 interface identifiers, there may 901 exist privacy risks in the use of 802.11p interface identifiers. 902 However, in outdoors vehicular settings, the privacy risks are more 903 important than in indoors settings. New risks are induced by the 904 possibility of attacker sniffers deployed along routes which listen 905 for IP packets of vehicles passing by. For this reason, in the 906 802.11p deployments, there is a strong necessity to use protection 907 tools such as dynamically changing MAC addresses. This may help 908 mitigate privacy risks to a certain level. On another hand, it may 909 have an impact in the way typical IPv6 address auto-configuration is 910 performed for vehicles (SLAAC would rely on MAC addresses amd would 911 hence dynamically change the affected IP address), in the way the 912 IPv6 Privacy addresses were used, and other effects. 914 8. IANA Considerations 916 9. Contributors 918 Romain Kuntz contributed extensively about IPv6 handovers between 919 links running outside the context of a BSS (802.11p links). 921 Tim Leinmueller contributed the idea of the use of IPv6 over 922 802.11-OCB for distribution of certificates. 924 Marios Makassikis, Jose Santa Lozano, Albin Severinson and Alexey 925 Voronov provided significant feedback on the experience of using IP 926 messages over 802.11-OCB in initial trials. 928 Michelle Wetterwald contributed extensively the MTU discussion 929 offering the ETSI ITS perspective, as well as other parts of the 930 document. 932 10. Acknowledgements 934 The authors would like to thank Witold Klaudel, Ryuji Wakikawa, 935 Emmanuel Baccelli, John Kenney, John Moring, Francois Simon, Dan 936 Romascanu, Konstantin Khait, Ralph Droms, Richard 'Dick' Roy, Ray 937 Hunter, Tom Kurihara, Michal Sojka, Jan de Jongh, Suresh Krishnan, 938 Dino Farinacci, Vincent Park, Jaehoon Paul Jeong, Gloria Gwynne, 939 Hans-Joachim Fischer, Russ Housley, Rex Buddenberg, and William 940 Whyte. Their valuable comments clarified certain issues and 941 generally helped to improve the document. 943 Pierre Pfister, Rostislav Lisovy, and others, wrote 802.11-OCB 944 drivers for linux and described how. 946 For the multicast discussion, the authors would like to thank Owen 947 DeLong, Joe Touch, Jen Linkova, Erik Kline, Brian Haberman and 948 participants to discussions in network working groups. 950 The authours would like to thank participants to the Birds-of- 951 a-Feather "Intelligent Transportation Systems" meetings held at IETF 952 in 2016. 954 11. References 956 11.1. Normative References 958 [I-D.ietf-6man-default-iids] 959 Gont, F., Cooper, A., Thaler, D., and S. LIU, 960 "Recommendation on Stable IPv6 Interface Identifiers", 961 draft-ietf-6man-default-iids-16 (work in progress), 962 September 2016. 964 [I-D.ietf-6man-ug] 965 Carpenter, B. and S. Jiang, "Significance of IPv6 966 Interface Identifiers", draft-ietf-6man-ug-06 (work in 967 progress), December 2013. 969 [I-D.ietf-tsvwg-ieee-802-11] 970 Szigeti, T. and F. Baker, "DiffServ to IEEE 802.11 971 Mapping", draft-ietf-tsvwg-ieee-802-11-01 (work in 972 progress), November 2016. 974 [I-D.jeong-ipwave-vehicular-networking-survey] 975 Jeong, J., Cespedes, S., Benamar, N., and J. Haerri, 976 "Survey on IP-based Vehicular Networking for Intelligent 977 Transportation Systems", draft-jeong-ipwave-vehicular- 978 networking-survey-00 (work in progress), October 2016. 980 [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission 981 of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, 982 DOI 10.17487/RFC1042, February 1988, 983 . 985 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 986 Requirement Levels", BCP 14, RFC 2119, 987 DOI 10.17487/RFC2119, March 1997, 988 . 990 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 991 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 992 December 1998, . 994 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 995 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 996 . 998 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 999 "Randomness Requirements for Security", BCP 106, RFC 4086, 1000 DOI 10.17487/RFC4086, June 2005, 1001 . 1003 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1004 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1005 . 1007 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1008 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1009 DOI 10.17487/RFC4861, September 2007, 1010 . 1012 [RFC5889] Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing 1013 Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889, 1014 September 2010, . 1016 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1017 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1018 2011, . 1020 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1021 Bormann, "Neighbor Discovery Optimization for IPv6 over 1022 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1023 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1024 . 1026 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 1027 Considerations for IPv6 Address Generation Mechanisms", 1028 RFC 7721, DOI 10.17487/RFC7721, March 2016, 1029 . 1031 11.2. Informative References 1033 [etsi-302663-v1.2.1p-2013] 1034 "Intelligent Transport Systems (ITS); Access layer 1035 specification for Intelligent Transport Systems operating 1036 in the 5 GHz frequency band, 2013-07, document 1037 en_302663v010201p.pdf, document freely available at URL 1038 http://www.etsi.org/deliver/etsi_en/302600_302699/302663/ 1039 01.02.01_60/en_302663v010201p.pdf downloaded on October 1040 17th, 2013.". 1042 [etsi-draft-102492-2-v1.1.1-2006] 1043 "Electromagnetic compatibility and Radio spectrum Matters 1044 (ERM); Intelligent Transport Systems (ITS); Part 2: 1045 Technical characteristics for pan European harmonized 1046 communications equipment operating in the 5 GHz frequency 1047 range intended for road safety and traffic management, and 1048 for non-safety related ITS applications; System Reference 1049 Document, Draft ETSI TR 102 492-2 V1.1.1, 2006-07, 1050 document tr_10249202v010101p.pdf freely available at URL 1051 http://www.etsi.org/deliver/etsi_tr/102400_102499/ 1052 10249202/01.01.01_60/tr_10249202v010101p.pdf downloaded on 1053 October 18th, 2013.". 1055 [fcc-cc] "'Report and Order, Before the Federal Communications 1056 Commission Washington, D.C. 20554', FCC 03-324, Released 1057 on February 10, 2004, document FCC-03-324A1.pdf, document 1058 freely available at URL 1059 http://www.its.dot.gov/exit/fcc_edocs.htm downloaded on 1060 October 17th, 2013.". 1062 [fcc-cc-172-184] 1063 "'Memorandum Opinion and Order, Before the Federal 1064 Communications Commission Washington, D.C. 20554', FCC 1065 06-10, Released on July 26, 2006, document FCC- 1066 06-110A1.pdf, document freely available at URL 1067 http://hraunfoss.fcc.gov/edocs_public/attachmatch/ 1068 FCC-06-110A1.pdf downloaded on June 5th, 2014.". 1070 [I-D.perkins-intarea-multicast-ieee802] 1071 Perkins, C., Stanley, D., Kumari, W., and J. Zuniga, 1072 "Multicast Considerations over IEEE 802 Wireless Media", 1073 draft-perkins-intarea-multicast-ieee802-01 (work in 1074 progress), September 2016. 1076 [I-D.petrescu-its-scenarios-reqs] 1077 Petrescu, A., Janneteau, C., Boc, M., and W. Klaudel, 1078 "Scenarios and Requirements for IP in Intelligent 1079 Transportation Systems", draft-petrescu-its-scenarios- 1080 reqs-03 (work in progress), October 2013. 1082 [ieee16094] 1083 "1609.2-2016 - IEEE Standard for Wireless Access in 1084 Vehicular Environments--Security Services for Applications 1085 and Management Messages; document freely available at URL 1086 https://standards.ieee.org/findstds/ 1087 standard/1609.2-2016.html retrieved on July 08th, 2016.". 1089 [ieee802.11-2012] 1090 "802.11-2012 - IEEE Standard for Information technology-- 1091 Telecommunications and information exchange between 1092 systems Local and metropolitan area networks--Specific 1093 requirements Part 11: Wireless LAN Medium Access Control 1094 (MAC) and Physical Layer (PHY) Specifications. Downloaded 1095 on October 17th, 2013, from IEEE Standards, document 1096 freely available at URL 1097 http://standards.ieee.org/findstds/ 1098 standard/802.11-2012.html retrieved on October 17th, 1099 2013.". 1101 [ieee802.11p-2010] 1102 "IEEE Std 802.11p(TM)-2010, IEEE Standard for Information 1103 Technology - Telecommunications and information exchange 1104 between systems - Local and metropolitan area networks - 1105 Specific requirements, Part 11: Wireless LAN Medium Access 1106 Control (MAC) and Physical Layer (PHY) Specifications, 1107 Amendment 6: Wireless Access in Vehicular Environments; 1108 document freely available at URL 1109 http://standards.ieee.org/getieee802/ 1110 download/802.11p-2010.pdf retrieved on September 20th, 1111 2013.". 1113 [ieeep1609.0-D2] 1114 "IEEE P1609.0/D2 Draft Guide for Wireless Access in 1115 Vehicular Environments (WAVE) Architecture. pdf, length 1116 879 Kb. Restrictions apply.". 1118 [ieeep1609.2-D17] 1119 "IEEE P1609.2(tm)/D17 Draft Standard for Wireless Access 1120 in Vehicular Environments - Security Services for 1121 Applications and Management Messages. pdf, length 2558 1122 Kb. Restrictions apply.". 1124 [ieeep1609.3-D9-2010] 1125 "IEEE P1609.3(tm)/D9, Draft Standard for Wireless Access 1126 in Vehicular Environments (WAVE) - Networking Services, 1127 August 2010. Authorized licensed use limited to: CEA. 1128 Downloaded on June 19, 2013 at 07:32:34 UTC from IEEE 1129 Xplore. Restrictions apply, document at persistent link 1130 http://ieeexplore.ieee.org/servlet/opac?punumber=5562705". 1132 [ieeep1609.4-D9-2010] 1133 "IEEE P1609.4(tm)/D9 Draft Standard for Wireless Access in 1134 Vehicular Environments (WAVE) - Multi-channel Operation. 1135 Authorized licensed use limited to: CEA. Downloaded on 1136 June 19, 2013 at 07:34:48 UTC from IEEE Xplore. 1137 Restrictions apply. Document at persistent link 1138 http://ieeexplore.ieee.org/servlet/opac?punumber=5551097". 1140 [TS103097] 1141 "Intelligent Transport Systems (ITS); Security; Security 1142 header and certificate formats; document freely available 1143 at URL http://www.etsi.org/deliver/ 1144 etsi_ts/103000_103099/103097/01.01.01_60/ 1145 ts_103097v010101p.pdf retrieved on July 08th, 2016.". 1147 Appendix A. ChangeLog 1149 The changes are listed in reverse chronological order, most recent 1150 changes appearing at the top of the list. 1152 From draft-ietf-ipwave-ipv6-over-80211ocb-00 to draft-ietf-ipwave- 1153 ipv6-over-80211ocb-01 1155 o Introduced message exchange diagram illustrating differences 1156 between 802.11 and 802.11 in OCB mode. 1158 o Introduced an appendix listing for information the set of 802.11 1159 messages that may be transmitted in OCB mode. 1161 o Removed appendix sections "Privacy Requirements", "Authentication 1162 Requirements" and "Security Certificate Generation". 1164 o Removed appendix section "Non IP Communications". 1166 o Introductory phrase in the Security Considerations section. 1168 o Improved the definition of "OCB". 1170 o Introduced theoretical stacked layers about IPv6 and IEEE layers 1171 including EPD. 1173 o Removed the appendix describing the details of prohibiting IPv6 on 1174 certain channels relevant to 802.11-OCB. 1176 o Added a brief reference in the privacy text about a precise clause 1177 in IEEE 1609.3 and .4. 1179 o Clarified the definition of a Road Side Unit. 1181 o Removed the discussion about security of WSA (because is non-IP). 1183 o Removed mentioning of the GeoNetworking discussion. 1185 o Moved references to scientific articles to a separate 'overview' 1186 draft, and referred to it. 1188 Appendix B. Changes Needed on a software driver 802.11a to become a 1189 802.11-OCB driver 1191 The 802.11p amendment modifies both the 802.11 stack's physical and 1192 MAC layers but all the induced modifications can be quite easily 1193 obtained by modifying an existing 802.11a ad-hoc stack. 1195 Conditions for a 802.11a hardware to be 802.11p compliant: 1197 o The chip must support the frequency bands on which the regulator 1198 recommends the use of ITS communications, for example using IEEE 1199 802.11p layer, in France: 5875MHz to 5925MHz. 1201 o The chip must support the half-rate mode (the internal clock 1202 should be able to be divided by two). 1204 o The chip transmit spectrum mask must be compliant to the "Transmit 1205 spectrum mask" from the IEEE 802.11p amendment (but experimental 1206 environments tolerate otherwise). 1208 o The chip should be able to transmit up to 44.8 dBm when used by 1209 the US government in the United States, and up to 33 dBm in 1210 Europe; other regional conditions apply. 1212 Changes needed on the network stack in OCB mode: 1214 o Physical layer: 1216 * The chip must use the Orthogonal Frequency Multiple Access 1217 (OFDM) encoding mode. 1219 * The chip must be set in half-mode rate mode (the internal clock 1220 frequency is divided by two). 1222 * The chip must use dedicated channels and should allow the use 1223 of higher emission powers. This may require modifications to 1224 the regulatory domains rules, if used by the kernel to enforce 1225 local specific restrictions. Such modifications must respect 1226 the location-specific laws. 1228 MAC layer: 1230 * All management frames (beacons, join, leave, and others) 1231 emission and reception must be disabled except for frames of 1232 subtype Action and Timing Advertisement (defined below). 1234 * No encryption key or method must be used. 1236 * Packet emission and reception must be performed as in ad-hoc 1237 mode, using the wildcard BSSID (ff:ff:ff:ff:ff:ff). 1239 * The functions related to joining a BSS (Association Request/ 1240 Response) and for authentication (Authentication Request/Reply, 1241 Challenge) are not called. 1243 * The beacon interval is always set to 0 (zero). 1245 * Timing Advertisement frames, defined in the amendment, should 1246 be supported. The upper layer should be able to trigger such 1247 frames emission and to retrieve information contained in 1248 received Timing Advertisements. 1250 Appendix C. Design Considerations 1252 The networks defined by 802.11-OCB are in many ways similar to other 1253 networks of the 802.11 family. In theory, the encapsulation of IPv6 1254 over 802.11-OCB could be very similar to the operation of IPv6 over 1255 other networks of the 802.11 family. However, the high mobility, 1256 strong link asymetry and very short connection makes the 802.11-OCB 1257 link significantly different from other 802.11 networks. Also, the 1258 automotive applications have specific requirements for reliability, 1259 security and privacy, which further add to the particularity of the 1260 802.11-OCB link. 1262 C.1. Vehicle ID 1264 Automotive networks require the unique representation of each of 1265 their node. Accordingly, a vehicle must be identified by at least 1266 one unique ID. The current specification at ETSI and at IEEE 1609 1267 identifies a vehicle by its MAC address uniquely obtained from the 1268 802.11-OCB NIC. 1270 A MAC address uniquely obtained from a IEEE 802.11-OCB NIC 1271 implicitely generates multiple vehicle IDs in case of multiple 1272 802.11-OCB NICs. A mechanims to uniquely identify a vehicle 1273 irrespectively to the different NICs and/or technologies is required. 1275 C.2. Reliability Requirements 1277 The dynamically changing topology, short connectivity, mobile 1278 transmitter and receivers, different antenna heights, and many-to- 1279 many communication types, make IEEE 802.11-OCB links significantly 1280 different from other IEEE 802.11 links. Any IPv6 mechanism operating 1281 on IEEE 802.11-OCB link MUST support strong link asymetry, spatio- 1282 temporal link quality, fast address resolution and transmission. 1284 IEEE 802.11-OCB strongly differs from other 802.11 systems to operate 1285 outside of the context of a Basic Service Set. This means in 1286 practice that IEEE 802.11-OCB does not rely on a Base Station for all 1287 Basic Service Set management. In particular, IEEE 802.11-OCB SHALL 1288 NOT use beacons. Any IPv6 mechanism requiring L2 services from IEEE 1289 802.11 beacons MUST support an alternative service. 1291 Channel scanning being disabled, IPv6 over IEEE 802.11-OCB MUST 1292 implement a mechanism for transmitter and receiver to converge to a 1293 common channel. 1295 Authentication not being possible, IPv6 over IEEE 802.11-OCB MUST 1296 implement an distributed mechanism to authenticate transmitters and 1297 receivers without the support of a DHCP server. 1299 Time synchronization not being available, IPv6 over IEEE 802.11-OCB 1300 MUST implement a higher layer mechanism for time synchronization 1301 between transmitters and receivers without the support of a NTP 1302 server. 1304 The IEEE 802.11-OCB link being asymetic, IPv6 over IEEE 802.11-OCB 1305 MUST disable management mechanisms requesting acknowledgements or 1306 replies. 1308 The IEEE 802.11-OCB link having a short duration time, IPv6 over IEEE 1309 802.11-OCB MUST implement fast IPv6 mobility management mechanisms. 1311 C.3. Multiple interfaces 1313 There are considerations for 2 or more IEEE 802.11-OCB interface 1314 cards per vehicle. For each vehicle taking part in road traffic, one 1315 IEEE 802.11-OCB interface card MUST be fully allocated for Non IP 1316 safety-critical communication. Any other IEEE 802.11-OCB may be used 1317 for other type of traffic. 1319 The mode of operation of these other wireless interfaces is not 1320 clearly defined yet. One possibility is to consider each card as an 1321 independent network interface, with a specific MAC Address and a set 1322 of IPv6 addresses. Another possibility is to consider the set of 1323 these wireless interfaces as a single network interface (not 1324 including the IEEE 802.11-OCB interface used by Non IP safety 1325 critical communications). This will require specific logic to 1326 ensure, for example, that packets meant for a vehicle in front are 1327 actually sent by the radio in the front, or that multiple copies of 1328 the same packet received by multiple interfaces are treated as a 1329 single packet. Treating each wireless interface as a separate 1330 network interface pushes such issues to the application layer. 1332 If Mobile IPv6 with NEMO extensions is used, then the MCoA RFC5648 1333 technology is relevant for Mobile Routers with multiple interfaces, 1334 deployed in vehicles. 1336 The privacy requirements of [] imply that if these multiple 1337 interfaces are represented by many network interface, a single 1338 renumbering event SHALL cause renumbering of all these interfaces. 1339 If one MAC changed and another stayed constant, external observers 1340 would be able to correlate old and new values, and the privacy 1341 benefits of randomization would be lost. 1343 The privacy requirements of Non IP safety-critical communications 1344 imply that if a change of pseudonyme occurs, renumbering of all other 1345 interfaces SHALL also occur. 1347 C.4. MAC Address Generation 1349 When designing the IPv6 over 802.11-OCB address mapping, we will 1350 assume that the MAC Addresses will change during well defined 1351 "renumbering events". The 48 bits randomized MAC addresses will have 1352 the following characteristics: 1354 o Bit "Local/Global" set to "locally admninistered". 1356 o Bit "Unicast/Multicast" set to "Unicast". 1358 o 46 remaining bits set to a random value, using a random number 1359 generator that meets the requirements of [RFC4086]. 1361 The way to meet the randomization requirements is to retain 46 bits 1362 from the output of a strong hash function, such as SHA256, taking as 1363 input a 256 bit local secret, the "nominal" MAC Address of the 1364 interface, and a representation of the date and time of the 1365 renumbering event. 1367 Appendix D. IEEE 802.11 Messages Transmitted in OCB mode 1369 For information, at the time of writing, this is the list of IEEE 1370 802.11 messages that may be transmitted in OCB mode, i.e. when 1371 dot11OCBActivated is true in a STA: 1373 o The STA may send management frames of subtype Action and, if the 1374 STA maintains a TSF Timer, subtype Timing Advertisement; 1376 o The STA may send control frames, except those of subtype PS-Poll, 1377 CF-End, and CF-End plus CFAck; 1379 o The STA may send data frames of subtype Data, Null, QoS Data, and 1380 QoS Null. 1382 Authors' Addresses 1384 Alexandre Petrescu 1385 CEA, LIST 1386 CEA Saclay 1387 Gif-sur-Yvette , Ile-de-France 91190 1388 France 1390 Phone: +33169089223 1391 Email: Alexandre.Petrescu@cea.fr 1393 Nabil Benamar 1394 Moulay Ismail University 1395 Morocco 1397 Phone: +212670832236 1398 Email: benamar73@gmail.com 1400 Jerome Haerri 1401 Eurecom 1402 Sophia-Antipolis 06904 1403 France 1405 Phone: +33493008134 1406 Email: Jerome.Haerri@eurecom.fr 1407 Christian Huitema 1408 Friday Harbor, WA 98250 1409 U.S.A. 1411 Email: huitema@huitema.net 1413 Jong-Hyouk Lee 1414 Sangmyung University 1415 31, Sangmyeongdae-gil, Dongnam-gu 1416 Cheonan 31066 1417 Republic of Korea 1419 Email: jonghyouk@smu.ac.kr 1421 Thierry Ernst 1422 YoGoKo 1423 France 1425 Email: thierry.ernst@yogoko.fr 1427 Tony Li 1428 Peloton Technology 1429 1060 La Avenida St. 1430 Mountain View, California 94043 1431 United States 1433 Phone: +16503957356 1434 Email: tony.li@tony.li