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If it is intended as a requirements expression, it should be rewritten using one of the combinations defined in RFC 2119; otherwise it should not be all-uppercase. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: All IPv6 multicast packets MUST be sent to NFC Destination Address, 0x3F (broadcast) and filtered at the IPv6 layer. When represented as a 16-bit address in a compressed header, it MUST be formed by padding on the left with a zero. In addition, the NFC Destination Address, 0x3F, MUST not be used as a unicast NFC address of SSAP or DSAP. -- The document date (March 21, 2016) is 2958 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 492 == Unused Reference: '12' is defined on line 752, 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 (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6Lo Working Group Y-G. Hong 3 Internet-Draft Y-H. Choi 4 Intended status: Standards Track ETRI 5 Expires: September 22, 2016 J-S. Youn 6 DONG-EUI Univ 7 D-K. Kim 8 KNU 9 J-H. Choi 10 Samsung Electronics Co., 11 March 21, 2016 13 Transmission of IPv6 Packets over Near Field Communication 14 draft-ietf-6lo-nfc-03 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 September 22, 2016. 47 Copyright Notice 49 Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . 4 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 . . . . . . . . . . . . . . . . . 5 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 . . . . . . . . . . . . . . . 8 72 4.1. Protocol Stacks . . . . . . . . . . . . . . . . . . . . . 8 73 4.2. Link Model . . . . . . . . . . . . . . . . . . . . . . . 9 74 4.3. Stateless Address Autoconfiguration . . . . . . . . . . . 10 75 4.4. IPv6 Link Local Address . . . . . . . . . . . . . . . . . 10 76 4.5. Neighbor Discovery . . . . . . . . . . . . . . . . . . . 11 77 4.6. Dispatch Header . . . . . . . . . . . . . . . . . . . . . 11 78 4.7. Header Compression . . . . . . . . . . . . . . . . . . . 12 79 4.8. Fragmentation and Reassembly . . . . . . . . . . . . . . 12 80 4.9. Unicast Address Mapping . . . . . . . . . . . . . . . . . 13 81 4.10. Multicast Address Mapping . . . . . . . . . . . . . . . . 13 82 5. Internet Connectivity Scenarios . . . . . . . . . . . . . . . 14 83 5.1. NFC-enabled Device Connected to the Internet . . . . . . 14 84 5.2. Isolated NFC-enabled Device Network . . . . . . . . . . . 15 85 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 86 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 87 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 88 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 89 9.1. Normative References . . . . . . . . . . . . . . . . . . 16 90 9.2. Informative References . . . . . . . . . . . . . . . . . 17 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 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 be existing together. Therefore, it is required 119 for them to communicate each other. NFC also has the strongest point 120 (e.g., secure communication distance of 10 cm) to prevent the third 121 party from attacking privacy. 123 When the number of devices and things having different air interface 124 technologies communicate 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 techiques with following 128 scopes. 130 o Overview of NFC technologies; 132 o Specifications for IPv6 over NFC; 134 * Neighbor Discovery; 136 * Addressing and Configuration; 138 * Header Compression; 140 * Fragmentation & Reassembly for a IPv6 datagram; 142 RFC4944 [1] specifies the transmission of IPv6 over IEEE 802.15.4. 143 The NFC link also has similar characteristics to that of IEEE 144 802.15.4. Many of the mechanisms defined in the RFC4944 [1] can be 145 applied to the transmission of IPv6 on NFC links. This document 146 specifies the details of IPv6 transmission over NFC links. 148 2. Conventions and Terminology 150 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 151 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 152 document are to be interpreted as described in [2]. 154 3. Overview of Near Field Communication Technology 156 NFC technology enables simple and safe two-way interactions between 157 electronic devices, allowing consumers to perform contactless 158 transactions, access digital content, and connect electronic devices 159 with a single touch. NFC complements many popular consumer level 160 wireless technologies, by utilizing the key elements in existing 161 standards for contactless card technology (ISO/IEC 14443 A&B and 162 JIS-X 6319-4). NFC can be compatible with existing contactless card 163 infrastructure and it enables a consumer to utilize one device across 164 different systems. 166 Extending the capability of contactless card technology, NFC also 167 enables devices to share information at a distance that is less than 168 10 cm with a maximum communication speed of 424 kbps. Users can 169 share business cards, make transactions, access information from a 170 smart poster or provide credentials for access control systems with a 171 simple touch. 173 NFC's bidirectional communication ability is ideal for establishing 174 connections with other technologies by the simplicity of touch. In 175 addition to the easy connection and quick transactions, simple data 176 sharing is also available. 178 3.1. Peer-to-peer Mode of NFC 180 NFC-enabled devices are unique in that they can support three modes 181 of operation: card emulation, peer-to-peer, and reader/writer. Peer- 182 to-peer mode enables two NFC-enabled devices to communicate with each 183 other to exchange information and share files, so that users of NFC- 184 enabled devices can quickly share contact information and other files 185 with a touch. Therefore, a NFC-enabled device can securely send IPv6 186 packets to any corresponding node on the Internet when a NFC-enabled 187 gateway is linked to the Internet. 189 3.2. Protocol Stacks of NFC 191 The IP protocol can use the services provided by Logical Link Control 192 Protocol (LLCP) in the NFC stack to provide reliable, two-way 193 transport of information between the peer devices. Figure 1 depicts 194 the NFC P2P protocol stack with IPv6 bindings to the LLCP. 196 For data communication in IPv6 over NFC, an IPv6 packet SHALL be 197 received at LLCP of NFC and transported to an Information Field in 198 Protocol Data Unit (I PDU) of LLCP of the NFC-enabled peer device. 199 Since LLCP does not support fragmentation and reassembly, upper 200 layers SHOULD support fragmentation and reassembly. For IPv6 201 addressing or address configuration, LLCP SHALL provide related 202 information, such as link layer addresses, to its upper layer. LLCP 203 to IPv6 protocol Binding SHALL transfer the SSAP and DSAP value to 204 the IPv6 over NFC protocol. SSAP stands for Source Service Access 205 Point, which is 6-bit value meaning a kind of Logical Link Control 206 (LLC) address, while DSAP means a LLC address of destination NFC- 207 enabled device. 209 | | 210 | | Application Layer 211 | Upper Layer Protocols | Transport Layer 212 | | Network Layer 213 | | | 214 +----------------------------------------+ <------------------ 215 | IPv6-LLCP Binding | | 216 +----------------------------------------+ NFC 217 | | Logical Link 218 | Logical Link Control Protocol | Layer 219 | (LLCP) | | 220 +----------------------------------------+ <------------------ 221 | | | 222 | Activities | | 223 | Digital Protocol | NFC 224 | | Physical 225 +----------------------------------------+ Layer 226 | | | 227 | RF Analog | | 228 | | | 229 +----------------------------------------+ <------------------ 231 Figure 1: Protocol Stacks of NFC 233 The LLCP consists of Logical Link Control (LLC) and MAC Mapping. The 234 MAC Mapping integrates an existing RF protocol into the LLCP 235 architecture. The LLC contains three components, such as Link 236 Management, Connection-oriented Transport, and Connection-less 237 Transport. The Link Management component is responsible for 238 serializing all connection-oriented and connectionless LLC PDU 239 (Protocol Data Unit) exchanges and for aggregation and disaggregation 240 of small PDUs. This component also guarantees asynchronous balanced 241 mode communication and provides link status supervision by performing 242 the symmetry procedure. The Connection-oriented Transport component 243 is responsible for maintaining all connection-oriented data exchanges 244 including connection set-up and termination. The Connectionless 245 Transport component is responsible for handling unacknowledged data 246 exchanges. 248 3.3. NFC-enabled Device Addressing 250 NFC-enabled devices are identified by 6-bit LLC address. In other 251 words, Any address SHALL be usable as both an SSAP and a DSAP 252 address. According to NFCForum-TS-LLCP_1.1 [3], address values 253 between 0 and 31 (00h - 1Fh) SHALL be reserved for well-known service 254 access points for Service Discovery Protocol (SDP). Address values 255 between 32 and 63 (20h - 3Fh) inclusively, SHALL be assigned by the 256 local LLC as the result of an upper layer service request. 258 3.4. NFC MAC PDU Size and MTU 260 As mentioned in Section 3.2, an IPv6 packet SHALL be received at LLCP 261 of NFC and transported to an Unnumbered Information Protocol Data 262 Unit (UI PDU) and an Information Field in Protocol Data Unit (I PDU) 263 of LLCP of the NFC-enabled peer device. The format of the UI PDU and 264 I PDU SHALL be as shown in Figure 2 and Figure 3. 266 0 0 1 1 267 0 6 0 6 268 +------+----+------+-------------------------------------------+ 269 |DDDDDD|1100|SSSSSS| Service Data Unit | 270 +------+----+------+-------------------------------------------+ 271 | <-- 2 bytes ---> | | 272 | <------------------- 128 ~ 2176 bytes ---------------------> | 273 | | 275 Figure 2: Format of the UI PDU in NFC 277 0 0 1 1 2 2 278 0 6 0 6 0 4 279 +------+----+------+----+----+---------------------------------+ 280 |DDDDDD|1100|SSSSSS|N(S)|N(R)| Service Data Unit | 281 +------+----+------+----+----+---------------------------------+ 282 | <------- 3 bytes --------> | | 283 | <------------------- 128 ~ 2176 bytes ---------------------> | 284 | | 286 Figure 3: Format of the I PDU in NFC 288 The I PDU sequence field SHALL contain two sequence numbers: The send 289 sequence number N(S) and the receive sequence number N(R). The send 290 sequence number N(S) SHALL indicate the sequence number associated 291 with this I PDU. The receive sequence number N(R) value SHALL 292 indicate that I PDUs numbered up through N(R) - 1 have been received 293 correctly by the sender of this I PDU and successfully passed to the 294 senders SAP identified in the SSAP field. These I PDUs SHALL be 295 considered as acknowledged. 297 The information field of an I PDU SHALL contain a single service data 298 unit. The maximum number of octets in the information field SHALL be 299 determined by the Maximum Information Unit (MIU) for the data link 300 connection. The default value of the MIU for I PDUs SHALL be 128 301 octets. The local and remote LLCs each establish and maintain 302 distinct MIU values for each data link connection endpoint. Also, An 303 LLC MAY announce a larger MIU for a data link connection by 304 transmitting an MIUX extension parameter within the information 305 field. If no MIUX parameter is transmitted, the default MIU value of 306 128 SHALL be used. Otherwise, the MTU size in NFC LLCP SHALL 307 calculate the MIU value as follows: 309 MIU = 128 + MIUX. 311 According to NFCForum-TS-LLCP_1.1 [3], format of the MIUX parameter 312 TLV is as shown in Figure 4. 314 0 0 1 2 3 315 0 8 6 2 1 316 +--------+--------+----------------+ 317 | Type | Length | Value | 318 +--------+--------+----+-----------+ 319 |00000010|00000010|1011| MIUX | 320 +--------+--------+----+-----------+ 321 | <-------> | 322 0x000 ~ 0x7FF 324 Figure 4: Format of the MIUX Parameter TLV 326 When the MIUX parameter is encoded as a TLV, the TLV Type field SHALL 327 be 0x02 and the TLV Length field SHALL be 0x02. The MIUX parameter 328 SHALL be encoded into the least significant 11 bits of the TLV Value 329 field. The unused bits in the TLV Value field SHALL be set to zero 330 by the sender and SHALL be ignored by the receiver. However, a 331 maximun value of the TLV Value field can be 0x7FF, and a maximum size 332 of the MTU in NFC LLCP SHALL calculate 2176 bytes. 334 4. Specification of IPv6 over NFC 336 NFC technology sets also has considerations and requirements owing to 337 low power consumption and allowed protocol overhead. 6LoWPAN 338 standards RFC4944 [1], RFC6775 [4], and RFC6282 [5] provide useful 339 functionality for reducing overhead which can be applied to BT-LE. 340 This functionality comprises of link-local IPv6 addresses and 341 stateless IPv6 address auto-configuration (see Section 4.3), Neighbor 342 Discovery (see Section 4.5) and header compression (see Section 4.7). 344 One of the differences between IEEE 802.15.4 and NFC is that the 345 former supports both star and mesh topology (and requires a routing 346 protocol), whereas NFC can support direct peer-to-peer connection and 347 simple mesh-like topology depending on NFC application scenarios 348 because of very short RF distance of 10 cm or less. 350 4.1. Protocol Stacks 352 Figure 5 illustrates IPv6 over NFC. Upper layer protocols can be 353 transport protocols (TCP and UDP), application layer, and the others 354 capable running on the top of IPv6. 356 | | Transport & 357 | Upper Layer Protocols | Application Layer 358 +----------------------------------------+ <------------------ 359 | | | 360 | IPv6 | | 361 | | Network 362 +----------------------------------------+ Layer 363 | Adaptation Layer for IPv6 over NFC | | 364 +----------------------------------------+ <------------------ 365 | IPv6-LLCP Binding | 366 | Logical Link Control Protocol | NFC Link Layer 367 | (LLCP) | | 368 +----------------------------------------+ <------------------ 369 | | | 370 | Activities | NFC 371 | Digital Protocol | Physical Layer 372 | RF Analog | | 373 | | | 374 +----------------------------------------+ <------------------ 376 Figure 5: Protocol Stacks for IPv6 over NFC 378 Adaptation layer for IPv6 over NFC SHALL support neighbor discovery, 379 address auto-configuration, header compression, and fragmentation & 380 reassembly. 382 4.2. Link Model 384 In the case of BT-LE, Logical Link Control and Adaptation Protocol 385 (L2CAP) supports fragmentation and reassembly (FAR) functionality; 386 therefore, adaptation layer for IPv6 over BT-LE does not have to 387 conduct the FAR procedure. The NFC LLCP, by contrast, does not 388 support the FAR functionality, so IPv6 over NFC needs to consider the 389 FAR functionality, defined in RFC4944 [1]. However, MTU on NFC link 390 can be configured in a connection procedure and extended enough to 391 fit the MTU of IPv6 packet. 393 The NFC link between two communicating devices is considered to be a 394 point-to-point link only. Unlike in BT-LE, NFC link does not 395 consider star topology and mesh network topology but peer-to-peer 396 topology and simple multi-hop topology. Due to this characteristics, 397 6LoWPAN functionality, such as addressing and auto-configuration, and 398 header compression, is specialized into NFC. 400 4.3. Stateless Address Autoconfiguration 402 A NFC-enabled device (i.e., 6LN) performs stateless address 403 autoconfiguration as per RFC4862 [6]. A 64-bit Interface identifier 404 (IID) for a NFC interface is formed by utilizing the 6-bit NFC LLCP 405 address (i.e., SSAP or DSAP) (see Section 3.3). In the viewpoint of 406 address configuration, such an IID MAY guarantee a stable IPv6 407 address because each data link connection is uniquely identified by 408 the pair of DSAP and SSAP included in the header of each LLC PDU in 409 NFC. 411 Following the guidance of RFC7136 [10], interface Identifiers of all 412 unicast addresses for NFC-enabled devices are formed on the basis of 413 64 bits long and constructed in a modified EUI-64 format as shown in 414 Figure 6. 416 0 1 3 4 5 6 417 0 6 2 8 8 3 418 +----------------+----------------+----------------+----------+------+ 419 |0000000000000000|0000000011111111|1111111000000000|0000000000| SSAP | 420 +----------------+----------------+----------------+----------+------+ 422 Figure 6: Formation of IID from NFC-enabled device adddress 424 In addition, the "Universal/Local" bit in the case of NFC-enabled 425 device address MUST be set to 0 RFC4291 [7]. 427 4.4. IPv6 Link Local Address 429 Only if the NFC-enabled device address is known to be a public 430 address the "Universal/Local" bit can be set to 1. The IPv6 link- 431 local address for a NFC-enabled device is formed by appending the 432 IID, to the prefix FE80::/64, as depicted in Figure 7. 434 0 0 0 1 435 0 1 6 2 436 0 0 4 7 437 +----------+------------------+----------------------------+ 438 |1111111010| zeros | Interface Identifier | 439 +----------+------------------+----------------------------+ 440 | | 441 | <---------------------- 128 bits ----------------------> | 442 | | 444 Figure 7: IPv6 link-local address in NFC 446 The tool for a 6LBR to obtain an IPv6 prefix for numbering the NFC 447 network is can be accomplished via DHCPv6 Prefix Delegation (RFC3633 448 [8]). 450 4.5. Neighbor Discovery 452 Neighbor Discovery Optimization for 6LoWPANs (RFC6775 [4]) describes 453 the neighbor discovery approach in several 6LoWPAN topologies, such 454 as mesh topology. NFC does not consider complicated mesh topology 455 but simple multi-hop network topology or directly connected peer-to- 456 peer network. Therefore, the following aspects of RFC6775 are 457 applicable to NFC: 459 1. In a case that a NFC-enabled device (6LN) is directly connected 460 to 6LBR, A NFC 6LN MUST register its address with the 6LBR by 461 sending a Neighbor Solicitation (NS) message with the Address 462 Registration Option (ARO) and process the Neighbor Advertisement 463 (NA) accordingly. In addition, DHCPv6 is used to assigned an 464 address, Duplicate Address Detection (DAD) is not required. 466 2. For sending Router Solicitations and processing Router 467 Advertisements the NFC 6LNs MUST follow Sections 5.3 and 5.4 of 468 the RFC6775. 470 4.6. Dispatch Header 472 All IPv6-over-NFC encapsulated datagrams transmitted over NFC are 473 prefixed by an encapsulation header stack consisting of a Dispatch 474 value followed by zero or more header fields. The only sequence 475 currently defined for IPv6-over-NFC is the LOWPAN_IPHC header 476 followed by payload, as depicted in Figure 8. 478 +---------------+---------------+--------------+ 479 | IPHC Dispatch | IPHC Header | Payload | 480 +---------------+---------------+--------------+ 482 Figure 8: A IPv6-over-NFC Encapsulated 6LOWPAN_IPHC Compressed IPv6 483 Datagram 485 The dispatch value may be treated as an unstructured namespace. Only 486 a single pattern is used to represent current IPv6-over-NFC 487 functionality. 489 +------------+--------------------+-----------+ 490 | Pattern | Header Type | Reference | 491 +------------+--------------------+-----------+ 492 | 01 1xxxxx | 6LOWPAN_IPHC | [RFC6282] | 493 +------------+--------------------+-----------+ 495 Figure 9: Dispatch Values 497 Other IANA-assigned 6LoWPAN Dispatch values do not apply to this 498 specification. 500 4.7. Header Compression 502 Header compression as defined in RFC6282 [5] , which specifies the 503 compression format for IPv6 datagrams on top of IEEE 802.15.4, is 504 REQUIRED in this document as the basis for IPv6 header compression on 505 top of NFC. All headers MUST be compressed according to RFC6282 506 encoding formats. 508 Therefore, IPv6 header compression in RFC6282 [5] MUST be 509 implemented. Further, implementations MAY also support Generic 510 Header Compression (GHC) of RFC7400 [11]. A node implementing GHC 511 MUST probe its peers for GHC support before applying GHC. 513 If a 16-bit address is required as a short address of IEEE 802.15.4, 514 it MUST be formed by padding the 6-bit NFC link-layer (node) address 515 to the left with zeros as shown in Figure 10. 517 0 1 518 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 520 | Padding(all zeros)| NFC Addr. | 521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 523 Figure 10: NFC short adress format 525 4.8. Fragmentation and Reassembly 527 NFC provides fragmentation and reassembly (FAR) for payloads from 128 528 bytes up to 2176 bytes as mention in Section 3.4. The MTU of a 529 general IPv6 packet can fit into a sigle NFC link frame. Therefore, 530 the FAR functionality as defined in RFC4944, which specifies the 531 fragmentation methods for IPv6 datagrams on top of IEEE 802.15.4, is 532 NOT REQUIRED in this document as the basis for IPv6 datagram FAR on 533 top of NFC. The NFC link connection for IPv6 over NFC MUST be 534 configured with an equivalent MIU size to fit the MTU of IPv6 Packet. 535 However, the default configuration of MIUX value is 0x480 in order to 536 fit the MTU (1280 bytes) of a IPv6 packet. 538 4.9. Unicast Address Mapping 540 The address resolution procedure for mapping IPv6 non-multicast 541 addresses into NFC link-layer addresses follows the general 542 description in Section 7.2 of RFC4861 [9], unless otherwise 543 specified. 545 The Source/Target link-layer Address option has the following form 546 when the addresses are 6-bit NFC link-layer (node) addresses. 548 0 1 549 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | Type | Length=1 | 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 | | 554 +- Padding (all zeros) -+ 555 | | 556 +- +-+-+-+-+-+-+ 557 | | NFC Addr. | 558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 560 Figure 11: Unicast address mapping 562 Option fields: 564 Type: 566 1: for Source Link-layer address. 568 2: for Target Link-layer address. 570 Length: 572 This is the length of this option (including the type and 573 length fields) in units of 8 octets. The value of this field 574 is 1 for 6-bit NFC node addresses. 576 NFC address: 578 The 6-bit address in canonical bit order. This is the unicast 579 address the interface currently responds to. 581 4.10. Multicast Address Mapping 583 All IPv6 multicast packets MUST be sent to NFC Destination Address, 584 0x3F (broadcast) and filtered at the IPv6 layer. When represented as 585 a 16-bit address in a compressed header, it MUST be formed by padding 586 on the left with a zero. In addition, the NFC Destination Address, 587 0x3F, MUST not be used as a unicast NFC address of SSAP or DSAP. 589 0 1 590 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 | Padding(all zeros)|1 1 1 1 1 1| 593 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 595 Figure 12: Multicast address mapping 597 5. Internet Connectivity Scenarios 599 As two typical scenarios, the NFC network can be isolated and 600 connected to the Internet. 602 5.1. NFC-enabled Device Connected to the Internet 604 One of the key applications by using adaptation technology of IPv6 605 over NFC is the most securely transmitting IPv6 packets because RF 606 distance between 6LN and 6LBR SHOULD be within 10 cm. If any third 607 party wants to hack into the RF between them, it MUST come to nearly 608 touch them. Applications can choose which kinds of air interfaces 609 (e.g., BT-LE, Wi-Fi, NFC, etc.) to send data depending 610 characteristics of data. NFC SHALL be the best solution for secured 611 and private information. 613 Figure 13 illustrates an example of NFC-enabled device network 614 connected to the Internet. Distance between 6LN and 6LBR SHOULD be 615 10 cm or less. If there is any of close laptop computers to a user, 616 it SHALL becomes the 6LBR. Additionally, When the user mounts a NFC- 617 enabled air interface adapter (e.g., portable small NFC dongle) on 618 the close laptop PC, the user's NFC-enabled device (6LN) can 619 communicate the laptop PC (6LBR) within 10 cm distance. 621 ************ 622 6LN ------------------- 6LBR -----* Internet *------- CN 623 | (dis. 10 cm or less) | ************ | 624 | | | 625 | <-------- NFC -------> | <----- IPv6 packet ------> | 626 | (IPv6 over NFC packet) | | 628 Figure 13: NFC-enabled device network connected to the Internet 630 5.2. Isolated NFC-enabled Device Network 632 In some scenarios, the NFC-enabled device network may transiently be 633 a simple isolated network as shown in the Figure 14. 635 6LN ---------------------- 6LR ---------------------- 6LN 636 | (10 cm or less) | (10 cm or less) | 637 | | | 638 | <--------- NFC --------> | <--------- NFC --------> | 639 | (IPv6 over NFC packet) | (IPv6 over NFC packet) | 641 Figure 14: Isolated NFC-enabled device network 643 In mobile phone markets, applications are designed and made by user 644 developers. They may image interesting applications, where three or 645 more mobile phones touch or attach each other to accomplish 646 outstanding performance. For instance, three or more mobile phones 647 can play multi-channel sound of music together. In addition, 648 attached three or more mobile phones can make an extended banner to 649 show longer sentences in a concert hall. 651 6. IANA Considerations 653 There are no IANA considerations related to this document. 655 7. Security Considerations 657 When interface identifiers (IIDs) are generated, devices and users 658 are required to consider mitigating various threats, such as 659 correlation of activities over time, location tracking, device- 660 specific vulnerability exploitation, and address scanning. 662 IPv6-over-NFC is, in practice, not used for long-lived links for big 663 size data transfer or multimedia streaming, but used for extremely 664 short-lived links (i.e., single touch-based approaches) for ID 665 verification and mobile payment. This will mitigate the threat of 666 correlation of activities over time. 668 IPv6-over-NFC uses an IPv6 interface identifier formed from a "Short 669 Address" and a set of well-known constant bits (such as padding with 670 '0's) for the modified EUI-64 format. However, the short address of 671 NFC link layer (LLC) is not generated as a physically permanent value 672 but logically generated for each connection. Thus, every single 673 touch connection can use a different short address of NFC link with 674 an extremely short-lived link. This can mitigate address scanning as 675 well as location tracking and device-specific vulnerability 676 exploitation. 678 However, malicious tries for one connection of a long-lived link with 679 NFC technology are not secure, so the method of deriving interface 680 identifiers from 6-bit NFC Link layer addresses is intended to 681 preserve global uniqueness when it is possible. Therefore, it 682 requires to protect from duplication through accident or forgery and 683 to define a way to include sufficient bit of entropy in the IPv6 684 interface identifier, such as random EUI-64. 686 8. Acknowledgements 688 We are grateful to the members of the IETF 6lo working group. 690 Michael Richardson, Suresh Krishnan, Pascal Thubert, Carsten Bormann, 691 and Alexandru Petrescu have provided valuable feedback for this 692 draft. 694 9. References 696 9.1. Normative References 698 [1] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 699 "Transmission of IPv6 Packets over IEEE 802.15.4 700 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 701 . 703 [2] Bradner, S., "Key words for use in RFCs to Indicate 704 Requirement Levels", BCP 14, RFC 2119, 705 DOI 10.17487/RFC2119, March 1997, 706 . 708 [3] "Logical Link Control Protocol version 1.1", NFC Forum 709 Technical Specification , June 2011. 711 [4] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 712 Bormann, "Neighbor Discovery Optimization for IPv6 over 713 Low-Power Wireless Personal Area Networks (6LoWPANs)", 714 RFC 6775, DOI 10.17487/RFC6775, November 2012, 715 . 717 [5] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 718 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 719 DOI 10.17487/RFC6282, September 2011, 720 . 722 [6] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 723 Address Autoconfiguration", RFC 4862, 724 DOI 10.17487/RFC4862, September 2007, 725 . 727 [7] Hinden, R. and S. Deering, "IP Version 6 Addressing 728 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 729 2006, . 731 [8] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 732 Host Configuration Protocol (DHCP) version 6", RFC 3633, 733 DOI 10.17487/RFC3633, December 2003, 734 . 736 [9] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 737 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 738 DOI 10.17487/RFC4861, September 2007, 739 . 741 [10] Carpenter, B. and S. Jiang, "Significance of IPv6 742 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, 743 February 2014, . 745 [11] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for 746 IPv6 over Low-Power Wireless Personal Area Networks 747 (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 748 2014, . 750 9.2. Informative References 752 [12] "Near Field Communication - Interface and Protocol (NFCIP- 753 1) 3rd Ed.", ECMA-340 , June 2013. 755 Authors' Addresses 757 Yong-Geun Hong 758 ETRI 759 161 Gajeong-Dong Yuseung-Gu 760 Daejeon 305-700 761 Korea 763 Phone: +82 42 860 6557 764 Email: yghong@etri.re.kr 766 Younghwan Choi 767 ETRI 768 218 Gajeongno, Yuseong 769 Daejeon 305-700 770 Korea 772 Phone: +82 42 860 1429 773 Email: yhc@etri.re.kr 774 Joo-Sang Youn 775 DONG-EUI University 776 176 Eomgwangno Busan_jin_gu 777 Busan 614-714 778 Korea 780 Phone: +82 51 890 1993 781 Email: joosang.youn@gmail.com 783 Dongkyun Kim 784 Kyungpook National University 785 80 Daehak-ro, Buk-gu 786 Daegu 702-701 787 Korea 789 Phone: +82 53 950 7571 790 Email: dongkyun@knu.ac.kr 792 JinHyouk Choi 793 Samsung Electronics Co., 794 129 Samsung-ro, Youngdong-gu 795 Suwon 447-712 796 Korea 798 Phone: +82 2 2254 0114 799 Email: jinchoe@samsung.com