idnits 2.17.1 draft-ietf-6lo-nfc-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The expression 'MAY NOT', while looking like RFC 2119 requirements text, is not defined in RFC 2119, and should not be used. Consider using 'MUST NOT' instead (if that is what you mean). Found 'MAY NOT' in this paragraph: NFC provides fragmentation and reassembly (FAR) for payloads from 128 bytes up to 2176 bytes as mentioned in Section 3.4. The MTU of a general IPv6 packet can fit into a single NFC link frame. Therefore, the FAR functionality as defined in RFC 4944, which specifies the fragmentation methods for IPv6 datagrams on top of IEEE 802.15.4, MAY NOT be required as the basis for IPv6 datagram FAR on top of NFC. The NFC link connection for IPv6 over NFC MUST be configured with an equivalent MIU size to fit the MTU of IPv6 Packet. If NFC devices support extension of the MTU, the MIUX value is 0x480 in order to fit the MTU (1280 bytes) of a IPv6 packet. -- The document date (June 4, 2017) is 2517 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: 'RFC6282' on line 447 == Unused Reference: '12' is defined on line 703, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. '3' ** Obsolete normative reference: RFC 3633 (ref. '8') (Obsoleted by RFC 8415) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6Lo Working Group Y-H. Choi 3 Internet-Draft Y-G. Hong 4 Intended status: Standards Track ETRI 5 Expires: December 6, 2017 J-S. Youn 6 Dongeui Univ 7 D-K. Kim 8 KNU 9 J-H. Choi 10 Samsung Electronics Co., 11 June 4, 2017 13 Transmission of IPv6 Packets over Near Field Communication 14 draft-ietf-6lo-nfc-07 16 Abstract 18 Near field communication (NFC) is a set of standards for smartphones 19 and portable devices to establish radio communication with each other 20 by touching them together or bringing them into proximity, usually no 21 more than 10 cm. NFC standards cover communications protocols and 22 data exchange formats, and are based on existing radio-frequency 23 identification (RFID) standards including ISO/IEC 14443 and FeliCa. 24 The standards include ISO/IEC 18092 and those defined by the NFC 25 Forum. The NFC technology has been widely implemented and available 26 in mobile phones, laptop computers, and many other devices. This 27 document describes how IPv6 is transmitted over NFC using 6LowPAN 28 techniques. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on December 6, 2017. 47 Copyright Notice 49 Copyright (c) 2017 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3 66 3. Overview of Near Field Communication Technology . . . . . . . 4 67 3.1. Peer-to-peer Mode of NFC . . . . . . . . . . . . . . . . 4 68 3.2. Protocol Stacks of NFC . . . . . . . . . . . . . . . . . 4 69 3.3. NFC-enabled Device Addressing . . . . . . . . . . . . . . 6 70 3.4. NFC MAC PDU Size and MTU . . . . . . . . . . . . . . . . 6 71 4. Specification of IPv6 over NFC . . . . . . . . . . . . . . . 7 72 4.1. Protocol Stacks . . . . . . . . . . . . . . . . . . . . . 7 73 4.2. Link Model . . . . . . . . . . . . . . . . . . . . . . . 7 74 4.3. Stateless Address Autoconfiguration . . . . . . . . . . . 8 75 4.4. IPv6 Link Local Address . . . . . . . . . . . . . . . . . 9 76 4.5. Neighbor Discovery . . . . . . . . . . . . . . . . . . . 9 77 4.6. Dispatch Header . . . . . . . . . . . . . . . . . . . . . 10 78 4.7. Header Compression . . . . . . . . . . . . . . . . . . . 10 79 4.8. Fragmentation and Reassembly . . . . . . . . . . . . . . 11 80 4.9. Unicast Address Mapping . . . . . . . . . . . . . . . . . 11 81 4.10. Multicast Address Mapping . . . . . . . . . . . . . . . . 12 82 5. Internet Connectivity Scenarios . . . . . . . . . . . . . . . 12 83 5.1. NFC-enabled Device Connected to the Internet . . . . . . 12 84 5.2. Isolated NFC-enabled Device Network . . . . . . . . . . . 13 85 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 86 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 87 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 88 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 89 9.1. Normative References . . . . . . . . . . . . . . . . . . 14 90 9.2. Informative References . . . . . . . . . . . . . . . . . 15 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 93 1. Introduction 95 NFC is a set of short-range wireless technologies, typically 96 requiring a distance of 10 cm or less. NFC operates at 13.56 MHz on 97 ISO/IEC 18000-3 air interface and at rates ranging from 106 kbit/s to 98 424 kbit/s. NFC always involves an initiator and a target; the 99 initiator actively generates an RF field that can power a passive 100 target. This enables NFC targets to take very simple form factors 101 such as tags, stickers, key fobs, or cards that do not require 102 batteries. NFC peer-to-peer communication is possible, provided both 103 devices are powered. NFC builds upon RFID systems by allowing two- 104 way communication between endpoints, where earlier systems such as 105 contactless smart cards were one-way only. It has been used in 106 devices such as mobile phones, running Android operating system, 107 named with a feature called "Android Beam". In addition, it is 108 expected for the other mobile phones, running the other operating 109 systems (e.g., iOS, etc.) to be equipped with NFC technology in the 110 near future. 112 Considering the potential for exponential growth in the number of 113 heterogeneous air interface technologies, NFC would be widely used as 114 one of the other air interface technologies, such as Bluetooth Low 115 Energy (BT-LE), Wi-Fi, and so on. Each of the heterogeneous air 116 interface technologies has its own characteristics, which cannot be 117 covered by the other technologies, so various kinds of air interface 118 technologies would co-exist together. Therefore, it is required for 119 them to communicate with each other. NFC also has the strongest 120 ability (e.g., secure communication distance of 10 cm) to prevent a 121 third party from attacking privacy. 123 When the number of devices and things having different air interface 124 technologies communicate with each other, IPv6 is an ideal internet 125 protocols owing to its large address space. Also, NFC would be one 126 of the endpoints using IPv6. Therefore, this document describes how 127 IPv6 is transmitted over NFC using 6LoWPAN techniques. 129 RFC4944 [1] specifies the transmission of IPv6 over IEEE 802.15.4. 130 The NFC link also has similar characteristics to that of IEEE 131 802.15.4. Many of the mechanisms defined in RFC 4944 [1] can be 132 applied to the transmission of IPv6 on NFC links. This document 133 specifies the details of IPv6 transmission over NFC links. 135 2. Conventions and Terminology 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 139 document are to be interpreted as described in [2]. 141 3. Overview of Near Field Communication Technology 143 NFC technology enables simple and safe two-way interactions between 144 electronic devices, allowing consumers to perform contactless 145 transactions, access digital content, and connect electronic devices 146 with a single touch. NFC complements many popular consumer level 147 wireless technologies, by utilizing the key elements in existing 148 standards for contactless card technology (ISO/IEC 14443 A&B and 149 JIS-X 6319-4). NFC can be compatible with existing contactless card 150 infrastructure and it enables a consumer to utilize one device across 151 different systems. 153 Extending the capability of contactless card technology, NFC also 154 enables devices to share information at a distance that is less than 155 10 cm with a maximum communication speed of 424 kbps. Users can 156 share business cards, make transactions, access information from a 157 smart poster or provide credentials for access control systems with a 158 simple touch. 160 NFC's bidirectional communication ability is ideal for establishing 161 connections with other technologies by the simplicity of touch. In 162 addition to the easy connection and quick transactions, simple data 163 sharing is also available. 165 3.1. Peer-to-peer Mode of NFC 167 NFC-enabled devices are unique in that they can support three modes 168 of operation: card emulation, peer-to-peer, and reader/writer. Peer- 169 to-peer mode enables two NFC-enabled devices to communicate with each 170 other to exchange information and share files, so that users of NFC- 171 enabled devices can quickly share contact information and other files 172 with a touch. Therefore, an NFC-enabled device can securely send 173 IPv6 packets to any corresponding node on the Internet when an NFC- 174 enabled gateway is linked to the Internet. 176 3.2. Protocol Stacks of NFC 178 IP can use the services provided by the Logical Link Control Protocol 179 (LLCP) in the NFC stack to provide reliable, two-way transport of 180 information between the peer devices. Figure 1 depicts the NFC P2P 181 protocol stack with IPv6 bindings to LLCP. 183 For data communication in IPv6 over NFC, an IPv6 packet SHALL be 184 passed down to LLCP of NFC and transported to an Information Field in 185 Protocol Data Unit (I PDU) of LLCP of the NFC-enabled peer device. 186 LLCP does not support fragmentation and reassembly. For IPv6 187 addressing or address configuration, LLCP SHALL provide related 188 information, such as link layer addresses, to its upper layer. The 189 LLCP to IPv6 protocol binding SHALL transfer the SSAP and DSAP value 190 to the IPv6 over NFC protocol. SSAP stands for Source Service Access 191 Point, which is a 6-bit value meaning a kind of Logical Link Control 192 (LLC) address, while DSAP means an LLC address of the destination 193 NFC-enabled device. 195 | | 196 | | Application Layer 197 | Upper Layer Protocols | Transport Layer 198 | | Network Layer 199 | | | 200 +----------------------------------------+ <------------------ 201 | IPv6-LLCP Binding | | 202 +----------------------------------------+ NFC 203 | | Logical Link 204 | Logical Link Control Protocol | Layer 205 | (LLCP) | | 206 +----------------------------------------+ <------------------ 207 | | | 208 | Activities | | 209 | Digital Protocol | NFC 210 | | Physical 211 +----------------------------------------+ Layer 212 | | | 213 | RF Analog | | 214 | | | 215 +----------------------------------------+ <------------------ 217 Figure 1: Protocol Stacks of NFC 219 The LLCP consists of Logical Link Control (LLC) and MAC Mapping. The 220 MAC Mapping integrates an existing RF protocol into the LLCP 221 architecture. The LLC contains three components, such as Link 222 Management, Connection-oriented Transport, and Connection-less 223 Transport. The Link Management component is responsible for 224 serializing all connection-oriented and connection-less LLC PDU 225 (Protocol Data Unit) exchanges and for aggregation and disaggregation 226 of small PDUs. This component also guarantees asynchronous balanced 227 mode communication and provides link status supervision by performing 228 the symmetry procedure. The Connection-oriented Transport component 229 is responsible for maintaining all connection-oriented data exchanges 230 including connection set-up and termination. The Connectionless 231 Transport component is responsible for handling unacknowledged data 232 exchanges. 234 3.3. NFC-enabled Device Addressing 236 According to NFCForum-TS-LLCP_1.3 [3], NFC-enabled devices have two 237 types of 6-bit addresses (i.e., SSAP and DSAP) to identify service 238 access points. The several service access points can be installed on 239 a NFC device. However, the SSAP and DSAP can be used as identifiers 240 for NFC link connections with the IPv6 over NFC adaptation layer. 241 Therefore, the SSAP can be used to generate an IPv6 interface 242 identifier. Address values between 00h and 0Fh of SSAP and DSAP are 243 reserved for identifying the well-known service access points, which 244 are defined in the NFC Forum Assigned Numbers Register. Address 245 values between 10h and 1Fh SHALL be assigned by the local LLC to 246 services registered by local service environment. In addition, 247 address values between 20h and 3Fh SHALL be assigned by the local LLC 248 as a result of an upper layer service request. Therefore, the 249 address values between 20h and 3Fh can be used for generating IPv6 250 interface identifiers. 252 3.4. NFC MAC PDU Size and MTU 254 As mentioned in Section 3.2, an IPv6 packet SHALL passed down to LLCP 255 of NFC and transported to an Unnumbered Information Protocol Data 256 Unit (UI PDU) and an Information Field in Protocol Data Unit (I PDU) 257 of LLCP of the NFC-enabled peer device. 259 The information field of an I PDU SHALL contain a single service data 260 unit. The maximum number of octets in the information field is 261 determined by the Maximum Information Unit (MIU) for the data link 262 connection. The default value of the MIU for I PDUs SHALL be 128 263 octets. The local and remote LLCs each establish and maintain 264 distinct MIU values for each data link connection endpoint. Also, an 265 LLC MAY announce a larger MIU for a data link connection by 266 transmitting an MIUX extension parameter within the information 267 field. If no MIUX parameter is transmitted, the default MIU value of 268 128 SHALL be used. Otherwise, the MTU size in NFC LLCP SHALL 269 calculate the MIU value as follows: 271 MIU = 128 + MIUX. 273 When the MIUX parameter is encoded as a TLV, the TLV Type field SHALL 274 be 0x02 and the TLV Length field SHALL be 0x02. The MIUX parameter 275 SHALL be encoded into the least significant 11 bits of the TLV Value 276 field. The unused bits in the TLV Value field SHALL be set to zero 277 by the sender and SHALL be ignored by the receiver. However, a 278 maximum value of the TLV Value field can be 0x7FF, and a maximum size 279 of the MTU in NFC LLCP is 2176 bytes. 281 4. Specification of IPv6 over NFC 283 NFC technology also has considerations and requirements owing to low 284 power consumption and allowed protocol overhead. 6LoWPAN standards 285 RFC 4944 [1], RFC 6775 [4], and RFC 6282 [5] provide useful 286 functionality for reducing overhead which can be applied to NFC. 287 This functionality consists of link-local IPv6 addresses and 288 stateless IPv6 address auto-configuration (see Section 4.3), Neighbor 289 Discovery (see Section 4.5) and header compression (see Section 4.7). 291 4.1. Protocol Stacks 293 Figure 2 illustrates IPv6 over NFC. Upper layer protocols can be 294 transport layer protocols (TCP and UDP), application layer protocols, 295 and others capable running on top of IPv6. 297 | | Transport & 298 | Upper Layer Protocols | Application Layer 299 +----------------------------------------+ <------------------ 300 | | | 301 | IPv6 | | 302 | | Network 303 +----------------------------------------+ Layer 304 | Adaptation Layer for IPv6 over NFC | | 305 +----------------------------------------+ <------------------ 306 | IPv6-LLCP Binding | 307 | Logical Link Control Protocol | NFC Link Layer 308 | (LLCP) | | 309 +----------------------------------------+ <------------------ 310 | | | 311 | Activities | NFC 312 | Digital Protocol | Physical Layer 313 | RF Analog | | 314 | | | 315 +----------------------------------------+ <------------------ 317 Figure 2: Protocol Stacks for IPv6 over NFC 319 The adaptation layer for IPv6 over NFC SHALL support neighbor 320 discovery, stateless address auto-configuration, header compression, 321 and fragmentation & reassembly. 323 4.2. Link Model 325 In the case of BT-LE, the Logical Link Control and Adaptation 326 Protocol (L2CAP) supports fragmentation and reassembly (FAR) 327 functionality; therefore, the adaptation layer for IPv6 over BT-LE 328 does not have to conduct the FAR procedure. The NFC LLCP, in 329 contrast, does not support the FAR functionality, so IPv6 over NFC 330 needs to consider the FAR functionality, defined in RFC 4944 [1]. 331 However, the MTU on an NFC link can be configured in a connection 332 procedure and extended enough to fit the MTU of IPv6 packet (see 333 Section 4.8). 335 The NFC link between two communicating devices is considered to be a 336 point-to-point link only. Unlike in BT-LE, an NFC link does not 337 support a star topology or mesh network topology but only direct 338 connections between two devices. Furthermore, the NFC link layer 339 does not support packet forwarding in link layer. Due to this 340 characteristics, 6LoWPAN functionalities, such as addressing and 341 auto-configuration, and header compression, need to be specialized 342 into IPv6 over NFC. 344 4.3. Stateless Address Autoconfiguration 346 An NFC-enabled device (i.e., 6LN) performs stateless address 347 autoconfiguration as per RFC 4862 [6]. A 64-bit Interface identifier 348 (IID) for an NFC interface is formed by utilizing the 6-bit NFC LLCP 349 address (see Section 3.3). In the viewpoint of address 350 configuration, such an IID SHOULD guarantee a stable IPv6 address 351 because each data link connection is uniquely identified by the pair 352 of DSAP and SSAP included in the header of each LLC PDU in NFC. 354 Following the guidance of RFC 7136 [10], interface identifiers of all 355 unicast addresses for NFC-enabled devices are 64 bits long and 356 constructed in a modified EUI-64 format as shown in Figure 3. 358 0 1 3 4 6 359 0 6 2 8 3 360 +----------------+----------------+----------------+-----------------+ 361 |RRRRRRuRRRRRRRRR|RRRRRRRR11111111|11111110RRRRRRRR|RRRRRRRRRRRRRRRRR| 362 +----------------+----------------+----------------+-----------------+ 364 Figure 3: Formation of IID from NFC-enabled device address 366 The 'R' bits are output values which MAY be created by mechanisms 367 like hash functions with input values, i.e., the SSAP and other 368 values (e.g., a prefix and a nonce) because the 6-bit address of SSAP 369 is easy and short to be targeted by attacks of third party (e.g., 370 address scanning). Figure 4 shows an example for IID creation. The 371 F() means a mechanism to make a output value for 64-bit IID, and an 372 parameter, "nonce" is an example input value for making the different 373 output values. 375 IID = F( SHA-256(6-bit SSAP, 64-bit Prefix), 'u' bit, nonce ) 377 Figure 4: An example of an IID creation mechanism 379 In addition, the "Universal/Local" bit (i.e., the 'u' bit) of an NFC- 380 enabled device address MUST be set to 0 RFC 4291 [7]. 382 4.4. IPv6 Link Local Address 384 Only if the NFC-enabled device address is known to be a public 385 address, the "Universal/Local" bit be set to 1. The IPv6 link-local 386 address for an NFC-enabled device is formed by appending the IID, to 387 the prefix FE80::/64, as depicted in Figure 5. 389 0 0 0 1 390 0 1 6 2 391 0 0 4 7 392 +----------+------------------+----------------------------+ 393 |1111111010| zeros | Interface Identifier | 394 +----------+------------------+----------------------------+ 395 | | 396 | <---------------------- 128 bits ----------------------> | 397 | | 399 Figure 5: IPv6 link-local address in NFC 401 The tool for a 6LBR to obtain an IPv6 prefix for numbering the NFC 402 network is can be accomplished via DHCPv6 Prefix Delegation (RFC 3633 403 [8]). 405 4.5. Neighbor Discovery 407 Neighbor Discovery Optimization for 6LoWPANs (RFC 6775 [4]) describes 408 the neighbor discovery approach in several 6LoWPAN topologies, such 409 as mesh topology. NFC does not support a complicated mesh topology 410 but only a simple multi-hop network topology or directly connected 411 peer-to-peer network. Therefore, the following aspects of RFC 6775 412 are applicable to NFC: 414 1. In a case that an NFC-enabled device (6LN) is directly connected 415 to a 6LBR, an NFC 6LN MUST register its address with the 6LBR by 416 sending a Neighbor Solicitation (NS) message with the Address 417 Registration Option (ARO) and process the Neighbor Advertisement 418 (NA) accordingly. In addition, if DHCPv6 is used to assign an 419 address, Duplicate Address Detection (DAD) MAY not be required. 421 2. For sending Router Solicitations and processing Router 422 Advertisements the NFC 6LNs MUST follow Sections 5.3 and 5.4 of 423 RFC 6775. 425 4.6. Dispatch Header 427 All IPv6-over-NFC encapsulated datagrams are prefixed by an 428 encapsulation header stack consisting of a Dispatch value followed by 429 zero or more header fields. The only sequence currently defined for 430 IPv6-over-NFC is the LOWPAN_IPHC header followed by payload, as 431 depicted in Figure 6. 433 +---------------+---------------+--------------+ 434 | IPHC Dispatch | IPHC Header | Payload | 435 +---------------+---------------+--------------+ 437 Figure 6: A IPv6-over-NFC Encapsulated 6LOWPAN_IPHC Compressed IPv6 438 Datagram 440 The dispatch value may be treated as an unstructured namespace. Only 441 a single pattern is used to represent current IPv6-over-NFC 442 functionality. 444 +------------+--------------------+-----------+ 445 | Pattern | Header Type | Reference | 446 +------------+--------------------+-----------+ 447 | 01 1xxxxx | 6LOWPAN_IPHC | [RFC6282] | 448 +------------+--------------------+-----------+ 450 Figure 7: Dispatch Values 452 Other IANA-assigned 6LoWPAN Dispatch values do not apply to this 453 specification. 455 4.7. Header Compression 457 Header compression as defined in RFC 6282 [5], which specifies the 458 compression format for IPv6 datagrams on top of IEEE 802.15.4, is 459 REQUIRED in this document as the basis for IPv6 header compression on 460 top of NFC. All headers MUST be compressed according to RFC 6282 461 encoding formats. 463 Therefore, IPv6 header compression in RFC 6282 [5] MUST be 464 implemented. Further, implementations MAY also support Generic 465 Header Compression (GHC) of RFC 7400 [11]. 467 If a 16-bit address is required as a short address, it MUST be formed 468 by padding the 6-bit NFC link-layer (node) address to the left with 469 zeros as shown in Figure 8. 471 0 1 472 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 | Padding(all zeros)| NFC Addr. | 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 Figure 8: NFC short address format 479 4.8. Fragmentation and Reassembly 481 NFC provides fragmentation and reassembly (FAR) for payloads from 128 482 bytes up to 2176 bytes as mentioned in Section 3.4. The MTU of a 483 general IPv6 packet can fit into a single NFC link frame. Therefore, 484 the FAR functionality as defined in RFC 4944, which specifies the 485 fragmentation methods for IPv6 datagrams on top of IEEE 802.15.4, MAY 486 NOT be required as the basis for IPv6 datagram FAR on top of NFC. 487 The NFC link connection for IPv6 over NFC MUST be configured with an 488 equivalent MIU size to fit the MTU of IPv6 Packet. If NFC devices 489 support extension of the MTU, the MIUX value is 0x480 in order to fit 490 the MTU (1280 bytes) of a IPv6 packet. 492 4.9. Unicast Address Mapping 494 The address resolution procedure for mapping IPv6 non-multicast 495 addresses into NFC link-layer addresses follows the general 496 description in Section 7.2 of RFC 4861 [9], unless otherwise 497 specified. 499 The Source/Target link-layer Address option has the following form 500 when the addresses are 6-bit NFC link-layer (node) addresses. 502 0 1 503 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 504 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 505 | Type | Length=1 | 506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 | | 508 +- Padding (all zeros) -+ 509 | | 510 +- +-+-+-+-+-+-+ 511 | | NFC Addr. | 512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 514 Figure 9: Unicast address mapping 516 Option fields: 518 Type: 520 1: for Source Link-layer address. 522 2: for Target Link-layer address. 524 Length: 526 This is the length of this option (including the type and 527 length fields) in units of 8 octets. The value of this field 528 is 1 for 6-bit NFC node addresses. 530 NFC address: 532 The 6-bit address in canonical bit order. This is the unicast 533 address the interface currently responds to. 535 4.10. Multicast Address Mapping 537 All IPv6 multicast packets MUST be sent to NFC Destination Address, 538 0x3F (broadcast) and be filtered at the IPv6 layer. When represented 539 as a 16-bit address in a compressed header, it MUST be formed by 540 padding on the left with a zero. In addition, the NFC Destination 541 Address, 0x3F, MUST NOT be used as a unicast NFC address of SSAP or 542 DSAP. 544 0 1 545 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 | Padding(all zeros)|1 1 1 1 1 1| 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 Figure 10: Multicast address mapping 552 5. Internet Connectivity Scenarios 554 As two typical scenarios, the NFC network can be isolated and 555 connected to the Internet. 557 5.1. NFC-enabled Device Connected to the Internet 559 One of the key applications of using IPv6 over NFC is securely 560 transmitting IPv6 packets because the RF distance between 6LN and 561 6LBR is typically within 10 cm. If any third party wants to hack 562 into the RF between them, it must come to nearly touch them. 563 Applications can choose which kinds of air interfaces (e.g., BT-LE, 564 Wi-Fi, NFC, etc.) to send data depending on the characteristics of 565 the data. 567 Figure 11 illustrates an example of an NFC-enabled device network 568 connected to the Internet. The distance between 6LN and 6LBR is 569 typically 10 cm or less. If there is any laptop computers close to a 570 user, it will become the a 6LBR. Additionally, when the user mounts 571 an NFC-enabled air interface adapter (e.g., portable NFC dongle) on 572 the close laptop PC, the user's NFC-enabled device (6LN) can 573 communicate with the laptop PC (6LBR) within 10 cm distance. 575 ************ 576 6LN ------------------- 6LBR -----* Internet *------- CN 577 | (dis. 10 cm or less) | ************ | 578 | | | 579 | <-------- NFC -------> | <----- IPv6 packet ------> | 580 | (IPv6 over NFC packet) | | 582 Figure 11: NFC-enabled device network connected to the Internet 584 5.2. Isolated NFC-enabled Device Network 586 In some scenarios, the NFC-enabled device network may transiently be 587 a simple isolated network as shown in the Figure 12. 589 6LN ---------------------- 6LR ---------------------- 6LN 590 | (10 cm or less) | (10 cm or less) | 591 | | | 592 | <--------- NFC --------> | <--------- NFC --------> | 593 | (IPv6 over NFC packet) | (IPv6 over NFC packet) | 595 Figure 12: Isolated NFC-enabled device network 597 In mobile phone markets, applications are designed and made by user 598 developers. They may image interesting applications, where three or 599 more mobile phones touch or attach each other to accomplish 600 outstanding performance. 602 6. IANA Considerations 604 There are no IANA considerations related to this document. 606 7. Security Considerations 608 When interface identifiers (IIDs) are generated, devices and users 609 are required to consider mitigating various threats, such as 610 correlation of activities over time, location tracking, device- 611 specific vulnerability exploitation, and address scanning. 613 IPv6-over-NFC is, in practice, not used for long-lived links for big 614 size data transfer or multimedia streaming, but used for extremely 615 short-lived links (i.e., single touch-based approaches) for ID 616 verification and mobile payment. This will mitigate the threat of 617 correlation of activities over time. 619 IPv6-over-NFC uses an IPv6 interface identifier formed from a "Short 620 Address" and a set of well-known constant bits (such as padding with 621 '0's) for the modified EUI-64 format. However, the short address of 622 NFC link layer (LLC) is not generated as a physically permanent value 623 but logically generated for each connection. Thus, every single 624 touch connection can use a different short address of NFC link with 625 an extremely short-lived link. This can mitigate address scanning as 626 well as location tracking and device-specific vulnerability 627 exploitation. 629 However, malicious tries for one connection of a long-lived link with 630 NFC technology are not secure, so the method of deriving interface 631 identifiers from 6-bit NFC Link layer addresses is intended to 632 preserve global uniqueness when it is possible. Therefore, it 633 requires a way to protect from duplication through accident or 634 forgery and to define a way to include sufficient bit of entropy in 635 the IPv6 interface identifier, such as random EUI-64. 637 8. Acknowledgements 639 We are grateful to the members of the IETF 6lo working group. 641 Michael Richardson, Suresh Krishnan, Pascal Thubert, Carsten Bormann, 642 and Alexandru Petrescu have provided valuable feedback for this 643 draft. 645 9. References 647 9.1. Normative References 649 [1] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 650 "Transmission of IPv6 Packets over IEEE 802.15.4 651 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 652 . 654 [2] Bradner, S., "Key words for use in RFCs to Indicate 655 Requirement Levels", BCP 14, RFC 2119, 656 DOI 10.17487/RFC2119, March 1997, 657 . 659 [3] "NFC Logical Link Control Protocol version 1.3", NFC Forum 660 Technical Specification , March 2016. 662 [4] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 663 Bormann, "Neighbor Discovery Optimization for IPv6 over 664 Low-Power Wireless Personal Area Networks (6LoWPANs)", 665 RFC 6775, DOI 10.17487/RFC6775, November 2012, 666 . 668 [5] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 669 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 670 DOI 10.17487/RFC6282, September 2011, 671 . 673 [6] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 674 Address Autoconfiguration", RFC 4862, 675 DOI 10.17487/RFC4862, September 2007, 676 . 678 [7] Hinden, R. and S. Deering, "IP Version 6 Addressing 679 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 680 2006, . 682 [8] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 683 Host Configuration Protocol (DHCP) version 6", RFC 3633, 684 DOI 10.17487/RFC3633, December 2003, 685 . 687 [9] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 688 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 689 DOI 10.17487/RFC4861, September 2007, 690 . 692 [10] Carpenter, B. and S. Jiang, "Significance of IPv6 693 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, 694 February 2014, . 696 [11] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for 697 IPv6 over Low-Power Wireless Personal Area Networks 698 (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 699 2014, . 701 9.2. Informative References 703 [12] "Near Field Communication - Interface and Protocol (NFCIP- 704 1) 3rd Ed.", ECMA-340 , June 2013. 706 Authors' Addresses 708 Younghwan Choi 709 Electronics and Telecommunications Research Institute 710 218 Gajeongno, Yuseung-gu 711 Daejeon 34129 712 Korea 714 Phone: +82 42 860 1429 715 Email: yhc@etri.re.kr 717 Yong-Geun Hong 718 Electronics and Telecommunications Research Institute 719 161 Gajeong-Dong Yuseung-gu 720 Daejeon 305-700 721 Korea 723 Phone: +82 42 860 6557 724 Email: yghong@etri.re.kr 726 Joo-Sang Youn 727 DONG-EUI University 728 176 Eomgwangno Busan_jin_gu 729 Busan 614-714 730 Korea 732 Phone: +82 51 890 1993 733 Email: joosang.youn@gmail.com 735 Dongkyun Kim 736 Kyungpook National University 737 80 Daehak-ro, Buk-gu 738 Daegu 702-701 739 Korea 741 Phone: +82 53 950 7571 742 Email: dongkyun@knu.ac.kr 743 JinHyouk Choi 744 Samsung Electronics Co., 745 129 Samsung-ro, Youngdong-gu 746 Suwon 447-712 747 Korea 749 Phone: +82 2 2254 0114 750 Email: jinchoe@samsung.com