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Versions: (draft-hong-6lo-ipv6-over-nfc) 00 01 02 03 04 05 06 07 08 09 10 11 12

6Lo Working Group                                           Y. Choi, Ed.
Internet-Draft                                                 Y-G. Hong
Intended status: Standards Track                                    ETRI
Expires: April 4, 2019                                         J-S. Youn
                                                            Dongeui Univ
                                                                D-K. Kim
                                                                     KNU
                                                               J-H. Choi
                                                Samsung Electronics Co.,
                                                         October 1, 2018


       Transmission of IPv6 Packets over Near Field Communication
                         draft-ietf-6lo-nfc-11

Abstract

   Near field communication (NFC) is a set of standards for smartphones
   and portable devices to establish radio communication with each other
   by touching them together or bringing them into proximity, usually no
   more than 10 cm.  NFC standards cover communications protocols and
   data exchange formats, and are based on existing radio-frequency
   identification (RFID) standards including ISO/IEC 14443 and FeliCa.
   The standards include ISO/IEC 18092 and those defined by the NFC
   Forum.  The NFC technology has been widely implemented and available
   in mobile phones, laptop computers, and many other devices.  This
   document describes how IPv6 is transmitted over NFC using 6LowPAN
   techniques.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 4, 2019.






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Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   3
   3.  Overview of Near Field Communication Technology . . . . . . .   4
     3.1.  Peer-to-peer Mode of NFC  . . . . . . . . . . . . . . . .   4
     3.2.  Protocol Stacks of NFC  . . . . . . . . . . . . . . . . .   4
     3.3.  NFC-enabled Device Addressing . . . . . . . . . . . . . .   6
     3.4.  MTU of NFC Link Layer . . . . . . . . . . . . . . . . . .   6
   4.  Specification of IPv6 over NFC  . . . . . . . . . . . . . . .   7
     4.1.  Protocol Stacks . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Link Model  . . . . . . . . . . . . . . . . . . . . . . .   8
     4.3.  Stateless Address Autoconfiguration . . . . . . . . . . .   9
     4.4.  IPv6 Link Local Address . . . . . . . . . . . . . . . . .   9
     4.5.  Neighbor Discovery  . . . . . . . . . . . . . . . . . . .  10
     4.6.  Dispatch Header . . . . . . . . . . . . . . . . . . . . .  11
     4.7.  Header Compression  . . . . . . . . . . . . . . . . . . .  11
     4.8.  Fragmentation and Reassembly  . . . . . . . . . . . . . .  12
     4.9.  Unicast and Multicast Address Mapping . . . . . . . . . .  12
   5.  Internet Connectivity Scenarios . . . . . . . . . . . . . . .  13
     5.1.  NFC-enabled Device Connected to the Internet  . . . . . .  13
     5.2.  Isolated NFC-enabled Device Network . . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17







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1.  Introduction

   NFC is a set of short-range wireless technologies, typically
   requiring a distance of 10 cm or less.  NFC operates at 13.56 MHz on
   ISO/IEC 18000-3 air interface and at rates ranging from 106 kbit/s to
   424 kbit/s [ECMA-340].  NFC always involves an initiator and a
   target; the initiator actively generates an RF field that can power a
   passive target.  This enables NFC targets to take very simple form
   factors such as tags, stickers, key fobs, or cards that do not
   require batteries.  NFC peer-to-peer communication is possible,
   provided both devices are powered.  NFC builds upon RFID systems by
   allowing two-way communication between endpoints, where earlier
   systems such as contactless smart cards were one-way only.  It has
   been used in devices such as mobile phones, running Android operating
   system, named with a feature called "Android Beam".  In addition, it
   is expected for the other mobile phones, running the other operating
   systems (e.g., iOS, etc.) to be equipped with NFC technology in the
   near future.

   Considering the potential for exponential growth in the number of
   heterogeneous air interface technologies, NFC would be widely used as
   one of the other air interface technologies, such as Bluetooth Low
   Energy (BT-LE), Wi-Fi, and so on.  Each of the heterogeneous air
   interface technologies has its own characteristics, which cannot be
   covered by the other technologies, so various kinds of air interface
   technologies would co-exist together.  Therefore, it is required for
   them to communicate with each other.  NFC also has the strongest
   ability (e.g., secure communication distance of 10 cm) to prevent a
   third party from attacking privacy.

   When the number of devices and things having different air interface
   technologies communicate with each other, IPv6 is an ideal internet
   protocols owing to its large address space.  Also, NFC would be one
   of the endpoints using IPv6.  Therefore, this document describes how
   IPv6 is transmitted over NFC using 6LoWPAN techniques.

   [RFC4944] specifies the transmission of IPv6 over IEEE 802.15.4.  The
   NFC link also has similar characteristics to that of IEEE 802.15.4.
   Many of the mechanisms defined in [RFC4944] can be applied to the
   transmission of IPv6 on NFC links.  This document specifies the
   details of IPv6 transmission over NFC links.

2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP




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   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Overview of Near Field Communication Technology

   NFC technology enables simple and safe two-way interactions between
   electronic devices, allowing consumers to perform contactless
   transactions, access digital content, and connect electronic devices
   with a single touch.  NFC complements many popular consumer level
   wireless technologies, by utilizing the key elements in existing
   standards for contactless card technology (ISO/IEC 14443 A&B and
   JIS-X 6319-4).  NFC can be compatible with existing contactless card
   infrastructure and it enables a consumer to utilize one device across
   different systems.

   Extending the capability of contactless card technology, NFC also
   enables devices to share information at a distance that is less than
   10 cm with a maximum communication speed of 424 kbps.  Users can
   share business cards, make transactions, access information from a
   smart poster or provide credentials for access control systems with a
   simple touch.

   NFC's bidirectional communication ability is ideal for establishing
   connections with other technologies by the simplicity of touch.  In
   addition to the easy connection and quick transactions, simple data
   sharing is also available.

3.1.  Peer-to-peer Mode of NFC

   NFC-enabled devices are unique in that they can support three modes
   of operation: card emulation, peer-to-peer, and reader/writer.  Peer-
   to-peer mode enables two NFC-enabled devices to communicate with each
   other to exchange information and share files, so that users of NFC-
   enabled devices can quickly share contact information and other files
   with a touch.  Therefore, an NFC-enabled device can securely send
   IPv6 packets to any corresponding node on the Internet when an NFC-
   enabled gateway is linked to the Internet.

3.2.  Protocol Stacks of NFC

   IP can use the services provided by the Logical Link Control Protocol
   (LLCP) in the NFC stack to provide reliable, two-way transport of
   information between the peer devices.  Figure 1 depicts the NFC P2P
   protocol stack with IPv6 bindings to LLCP.

   For data communication in IPv6 over NFC, an IPv6 packet MUST be
   passed down to LLCP of NFC and transported to an Information (I) and
   an Unnumbered Information (UI) Field in Protocol Data Unit (PDU) of



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   LLCP of the NFC-enabled peer device.  LLCP does not support
   fragmentation and reassembly.  For IPv6 addressing or address
   configuration, LLCP MUST provide related information, such as link
   layer addresses, to its upper layer.  The LLCP to IPv6 protocol
   binding MUST transfer the SSAP and DSAP value to the IPv6 over NFC
   protocol.  SSAP stands for Source Service Access Point, which is a
   6-bit value meaning a kind of Logical Link Control (LLC) address,
   while DSAP means an LLC address of the destination NFC-enabled
   device.

      |                                        |
      |                                        |  Application Layer
      |         Upper Layer Protocols          |   Transport Layer
      |                                        |    Network Layer
      |                                        |         |
      +----------------------------------------+ <------------------
      |            IPv6-LLCP Binding           |         |
      +----------------------------------------+        NFC
      |                                        |    Logical Link
      |      Logical Link Control Protocol     |       Layer
      |                 (LLCP)                 |         |
      +----------------------------------------+ <------------------
      |                                        |         |
      |               Activities               |         |
      |            Digital Protocol            |        NFC
      |                                        |      Physical
      +----------------------------------------+       Layer
      |                                        |         |
      |               RF Analog                |         |
      |                                        |         |
      +----------------------------------------+ <------------------

                     Figure 1: Protocol Stacks of NFC

   The LLCP consists of Logical Link Control (LLC) and MAC Mapping.  The
   MAC Mapping integrates an existing RF protocol into the LLCP
   architecture.  The LLC contains three components, such as Link
   Management, Connection-oriented Transport, and Connection-less
   Transport.  The Link Management component is responsible for
   serializing all connection-oriented and connection-less LLC PDU
   (Protocol Data Unit) exchanges and for aggregation and disaggregation
   of small PDUs.  This component also guarantees asynchronous balanced
   mode communication and provides link status supervision by performing
   the symmetry procedure.  The Connection-oriented Transport component
   is responsible for maintaining all connection-oriented data exchanges
   including connection set-up and termination.  The Connectionless
   Transport component is responsible for handling unacknowledged data
   exchanges.



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3.3.  NFC-enabled Device Addressing

   According to NFC Logical Link Control Protocol v1.3 [LLCP-1.3], NFC-
   enabled devices have two types of 6-bit addresses (i.e., SSAP and
   DSAP) to identify service access points.  The several service access
   points can be installed on a NFC device.  However, the SSAP and DSAP
   can be used as identifiers for NFC link connections with the IPv6
   over NFC adaptation layer.  Therefore, the SSAP can be used to
   generate an IPv6 interface identifier.  Address values between 00h
   and 0Fh of SSAP and DSAP are reserved for identifying the well-known
   service access points, which are defined in the NFC Forum Assigned
   Numbers Register.  Address values between 10h and 1Fh SHALL be
   assigned by the local LLC to services registered by local service
   environment.  In addition, address values between 20h and 3Fh SHALL
   be assigned by the local LLC as a result of an upper layer service
   request.  Therefore, the address values between 20h and 3Fh can be
   used for generating IPv6 interface identifiers.

3.4.  MTU of NFC Link Layer

   As mentioned in Section 3.2, an IPv6 packet MUST be passed down to
   LLCP of NFC and transported to an Unnumbered Information Protocol
   Data Unit (UI PDU) and an Information Field in Protocol Data Unit (I
   PDU) of LLCP of the NFC-enabled peer device.

   The information field of an I PDU contains a single service data
   unit.  The maximum number of octets in the information field is
   determined by the Maximum Information Unit (MIU) for the data link
   connection.  The default value of the MIU for I PDUs is 128 octets.
   The local and remote LLCs each establish and maintain distinct MIU
   values for each data link connection endpoint.  Also, an LLC MAY
   announce a larger MIU for a data link connection by transmitting an
   MIUX extension parameter within the information field.  If no MIUX
   parameter is transmitted, the default MIU value of 128 MUST be used.
   Otherwise, the MTU size in NFC LLCP MUST be calculated from the MIU
   value as follows:

                             MIU = 128 + MIUX.

   According to [LLCP-1.3], Figure 2 shows an example of the MIUX
   parameter TLV.  Each of TLV Type and TLV Length field is 1 byte, and
   TLV Value field is 2 bytes.









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                    0        0        1    2          3
                    0        8        6    2          1
                   +--------+--------+----------------+
                   |  Type  | Length |     Value      |
                   +--------+--------+----+-----------+
                   |00000010|00000010|1011|    MIUX   |
                   +--------+--------+----+-----------+
                                          | <-------> |
                                          0x000 ~ 0x7FF

                  Figure 2: Example of MIUX Parameter TLV

   When the MIUX parameter is encoded as a TLV option, the TLV Type
   field MUST be 0x02 and the TLV Length field MUST be 0x02.  The MIUX
   parameter MUST be encoded into the least significant 11 bits of the
   TLV Value field.  The unused bits in the TLV Value field MUST be set
   to zero by the sender and ignored by the receiver.  A maximum value
   of the TLV Value field can be 0x7FF, and a maximum size of the MTU in
   NFC LLCP is 2176 bytes including the 128 byte default of MIU.

4.  Specification of IPv6 over NFC

   NFC technology also has considerations and requirements owing to low
   power consumption and allowed protocol overhead. 6LoWPAN standards
   [RFC4944], [RFC6775], and [RFC6282] provide useful functionality for
   reducing overhead which can be applied to NFC.  This functionality
   consists of link-local IPv6 addresses and stateless IPv6 address
   auto-configuration (see Section 4.3), Neighbor Discovery (see
   Section 4.5) and header compression (see Section 4.7).

4.1.  Protocol Stacks

   Figure 3 illustrates IPv6 over NFC.  Upper layer protocols can be
   transport layer protocols (TCP and UDP), application layer protocols,
   and others capable running on top of IPv6.
















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      |                                        |     Transport &
      |         Upper Layer Protocols          |  Application Layer
      +----------------------------------------+ <------------------
      |                                        |         |
      |                 IPv6                   |         |
      |                                        |      Network
      +----------------------------------------+       Layer
      |   Adaptation Layer for IPv6 over NFC   |         |
      +----------------------------------------+ <------------------
      |            IPv6-LLCP Binding                     |
      |      Logical Link Control Protocol     |   NFC Link Layer
      |                 (LLCP)                 |         |
      +----------------------------------------+ <------------------
      |                                        |         |
      |               Activities               |        NFC
      |            Digital Protocol            |   Physical Layer
      |               RF Analog                |         |
      |                                        |         |
      +----------------------------------------+ <------------------

                Figure 3: Protocol Stacks for IPv6 over NFC

   The adaptation layer for IPv6 over NFC SHALL support neighbor
   discovery, stateless address auto-configuration, header compression,
   and fragmentation & reassembly.

4.2.  Link Model

   In the case of BT-LE, the Logical Link Control and Adaptation
   Protocol (L2CAP) supports fragmentation and reassembly (FAR)
   functionality; therefore, the adaptation layer for IPv6 over BT-LE
   does not have to conduct the FAR procedure.  The NFC LLCP, in
   contrast, does not support the FAR functionality, so IPv6 over NFC
   needs to consider the FAR functionality, defined in [RFC4944].
   However, the MTU on an NFC link can be configured in a connection
   procedure and extended enough to fit the MTU of IPv6 packet (see
   Section 4.8).

   This document does NOT RECOMMEND using FAR over NFC link due to
   simplicity of the protocol and implementation.  In addition, the
   implementation for this specification SHOULD use MIUX extension to
   communicate the MTU of the link to the peer as defined in
   Section 3.4.

   The NFC link between two communicating devices is considered to be a
   point-to-point link only.  Unlike in BT-LE, an NFC link does not
   support a star topology or mesh network topology but only direct
   connections between two devices.  Furthermore, the NFC link layer



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   does not support packet forwarding in link layer.  Due to this
   characteristics, 6LoWPAN functionalities, such as addressing and
   auto-configuration, and header compression, need to be specialized
   into IPv6 over NFC.

4.3.  Stateless Address Autoconfiguration

   An NFC-enabled device (i.e., 6LN) performs stateless address
   autoconfiguration as per [RFC4862].  A 64-bit Interface identifier
   (IID) for an NFC interface is formed by utilizing the 6-bit NFC LLCP
   address (see Section 3.3).  In the viewpoint of address
   configuration, such an IID SHOULD guarantee a stable IPv6 address
   because each data link connection is uniquely identified by the pair
   of DSAP and SSAP included in the header of each LLC PDU in NFC.

   Following the guidance of [RFC7136], interface identifiers of all
   unicast addresses for NFC-enabled devices are 64 bits long and
   constructed by using the generation algorithm of random (but stable)
   identifier (RID) [RFC7217] (see Figure 4).

                  0         1         3         4       6
                  0         6         2         8       3
                 +---------+---------+---------+---------+
                 |  Random (but stable) Identifier (RID) |
                 +---------+---------+---------+---------+

                   Figure 4: IID from NFC-enabled device

   The RID is an output which MAY be created by the algorithm, F() with
   input parameters.  One of the parameters is Net_IFace, and NFC Link
   Layer address (i.e., SSAP) MAY be a source of the NetIFace parameter.
   The 6-bit address of SSAP of NFC is easy and short to be targeted by
   attacks of third party (e.g., address scanning).  The F() can provide
   secured and stable IIDs for NFC-enabled devices.  In addition, an
   optional parameter, Network_ID MAY be used to increase the randomness
   of the generated IID.

4.4.  IPv6 Link Local Address

   Only if the NFC-enabled device address is known to be a public
   address, the "Universal/Local" bit be set to 1.  The IPv6 link-local
   address for an NFC-enabled device is formed by appending the IID, to
   the prefix FE80::/64, as depicted in Figure 5.








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        0          0                  0                          1
        0          1                  6                          2
        0          0                  4                          7
       +----------+------------------+----------------------------+
       |1111111010|       zeros      |    Interface Identifier    |
       +----------+------------------+----------------------------+
       |                                                          |
       | <---------------------- 128 bits ----------------------> |
       |                                                          |

                 Figure 5: IPv6 link-local address in NFC

   The tool for a 6LBR to obtain an IPv6 prefix for numbering the NFC
   network is can be accomplished via DHCPv6 Prefix Delegation
   ([RFC3633]).

4.5.  Neighbor Discovery

   Neighbor Discovery Optimization for 6LoWPANs ([RFC6775]) describes
   the neighbor discovery approach in several 6LoWPAN topologies, such
   as mesh topology.  NFC does not support a complicated mesh topology
   but only a simple multi-hop network topology or directly connected
   peer-to-peer network.  Therefore, the following aspects of RFC 6775
   are applicable to NFC:

   o  When an NFC-enabled device (6LN) is directly connected to a 6LBR,
      an NFC 6LN MUST register its address with the 6LBR by sending a
      Neighbor Solicitation (NS) message with the Address Registration
      Option (ARO) and process the Neighbor Advertisement (NA)
      accordingly.  In addition, if DHCPv6 is used to assign an address,
      Duplicate Address Detection (DAD) MAY not be required.

   o  When two or more NFC 6LNs(or 6LRs) meet, there MAY be two cases.
      One is that they meet with multi-hop connections, and the other is
      that they meet within a sigle hop range (e.g., isolated network).
      In a case of multi-hops, all of 6LNs, which have two or more
      connections with different neighbors, MAY be a router for
      6LR/6LBR.  In a case that they meet within a single hop and they
      have the same properties, any of them can be a router.  When the
      NFC nodes are not of uniform category (e.g., different MTU, level
      of remaining energy, connectivity, etc.), a performance-
      outstanding device can become a router.  Also, they MUST deliver
      their MTU information to neighbors with NFC LLCP protocols during
      connection initialization.  The router MAY also communicate other
      capabilities which is out of scope of this document.






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   o  For sending Router Solicitations and processing Router
      Advertisements, the NFC 6LNs MUST follow Sections 5.3 and 5.4 of
      [RFC6775].

4.6.  Dispatch Header

   All IPv6-over-NFC encapsulated datagrams are prefixed by an
   encapsulation header stack consisting of a Dispatch value followed by
   zero or more header fields.  The only sequence currently defined for
   IPv6-over-NFC is the LOWPAN_IPHC header followed by payload, as
   depicted in Figure 6.

             +---------------+---------------+--------------+
             | IPHC Dispatch |  IPHC Header  |    Payload   |
             +---------------+---------------+--------------+

    Figure 6: A IPv6-over-NFC Encapsulated 6LOWPAN_IPHC Compressed IPv6
                                 Datagram

   The dispatch value may be treated as an unstructured namespace.  Only
   a single pattern is used to represent current IPv6-over-NFC
   functionality.

              +------------+--------------------+-----------+
              |  Pattern   | Header Type        | Reference |
              +------------+--------------------+-----------+
              | 01  1xxxxx | 6LOWPAN_IPHC       | [RFC6282] |
              +------------+--------------------+-----------+

                         Figure 7: Dispatch Values

   Other IANA-assigned 6LoWPAN Dispatch values do not apply to this
   specification.

4.7.  Header Compression

   Header compression as defined in [RFC6282], which specifies the
   compression format for IPv6 datagrams on top of IEEE 802.15.4, is
   REQUIRED in this document as the basis for IPv6 header compression on
   top of NFC.  All headers MUST be compressed according to RFC 6282
   encoding formats.

   Therefore, IPv6 header compression in [RFC6282] MUST be implemented.
   Further, implementations MAY also support Generic Header Compression
   (GHC) of [RFC7400].






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   If a 16-bit address is required as a short address, it MUST be formed
   by padding the 6-bit NFC link-layer (node) address to the left with
   zeros as shown in Figure 8.

                      0                   1
                      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     | Padding(all zeros)| NFC Addr. |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 8: NFC short address format

4.8.  Fragmentation and Reassembly

   IPv6-over-NFC fragmentation and reassembly (FAR) for the payloads is
   NOT RECOMMENDED in this document as discussed in Section 3.4.  The
   NFC link connection for IPv6 over NFC MUST be configured with an
   equivalent MIU size to fit the MTU of IPv6 Packet.  The MIUX value is
   0x480 in order to fit the MTU (1280 bytes) of a IPv6 packet if NFC
   devices support extension of the MTU.  However, if the NFC device
   does not support extension, IPv6-over-NFC uses FAR with default MIU
   (128 bytes), as defined in [RFC4944].

4.9.  Unicast and Multicast Address Mapping

   The address resolution procedure for mapping IPv6 non-multicast
   addresses into NFC link-layer addresses follows the general
   description in Section 7.2 of [RFC4861], unless otherwise specified.

   The Source/Target link-layer Address option has the following form
   when the addresses are 6-bit NFC link-layer (node) addresses.

                      0                   1
                      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |      Type     |   Length=1    |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |                               |
                     +-     Padding (all zeros)     -+
                     |                               |
                     +-                  +-+-+-+-+-+-+
                     |                   | NFC Addr. |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 9: Unicast address mapping

   Option fields:




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      Type:

         1: for Source Link-layer address.

         2: for Target Link-layer address.

      Length:

         This is the length of this option (including the type and
         length fields) in units of 8 octets.  The value of this field
         is 1 for 6-bit NFC node addresses.

      NFC address:

         The 6-bit address in canonical bit order.  This is the unicast
         address the interface currently responds to.

   The NFC Link Layer does not support multicast.  Therefore, packets
   are always transmitted by unicast between two NFC-enabled devices.
   Even in the case where a 6LBR is attached to multiple 6LNs, the 6LBR
   cannot do a multicast to all the connected 6LNs.  If the 6LBR needs
   to send a multicast packet to all its 6LNs, it has to replicate the
   packet and unicast it on each link.

5.  Internet Connectivity Scenarios

   As two typical scenarios, the NFC network can be isolated and
   connected to the Internet.

5.1.  NFC-enabled Device Connected to the Internet

   One of the key applications of using IPv6 over NFC is securely
   transmitting IPv6 packets because the RF distance between 6LN and
   6LBR is typically within 10 cm.  If any third party wants to hack
   into the RF between them, it must come to nearly touch them.
   Applications can choose which kinds of air interfaces (e.g., BT-LE,
   Wi-Fi, NFC, etc.) to send data depending on the characteristics of
   the data.

   Figure 10 illustrates an example of an NFC-enabled device network
   connected to the Internet.  The distance between 6LN and 6LBR is
   typically 10 cm or less.  If there is any laptop computers close to a
   user, it will become the a 6LBR.  Additionally, when the user mounts
   an NFC-enabled air interface adapter (e.g., portable NFC dongle) on
   the close laptop PC, the user's NFC-enabled device (6LN) can
   communicate with the laptop PC (6LBR) within 10 cm distance.





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                                           ************
         6LN ------------------- 6LBR -----* Internet *------- CN
          |  (dis. 10 cm or less)  |       ************         |
          |                        |                            |
          | <-------- NFC -------> | <----- IPv6 packet ------> |
          | (IPv6 over NFC packet) |                            |

      Figure 10: NFC-enabled device network connected to the Internet

   Two or more LNs MAY be connected with a 6LBR, but each connection
   uses a different subnet.  The 6LBR is acting as a router and
   forwarding packets between 6LNs and the Internet.  Also, the 6LBR
   MUST ensure address collisions do not occur and forwards packets sent
   by one 6LN to another.

5.2.  Isolated NFC-enabled Device Network

   In some scenarios, the NFC-enabled device network may transiently be
   a simple isolated network as shown in the Figure 11.

         6LN ---------------------- 6LR ---------------------- 6LN
          |     (10 cm or less)      |     (10 cm or less)      |
          |                          |                          |
          | <--------- NFC --------> | <--------- NFC --------> |
          |   (IPv6 over NFC packet) |  (IPv6 over NFC packet)  |

              Figure 11: Isolated NFC-enabled device network

   In mobile phone markets, applications are designed and made by user
   developers.  They may image interesting applications, where three or
   more mobile phones touch or attach each other to accomplish
   outstanding performance.  In an isolated NFC-enabled device network,
   when two or more LRs MAY be connected with each other, and then they
   are acting like routers, the 6LR MUST ensure address collisions do
   not occur.

6.  IANA Considerations

   There are no IANA considerations related to this document.

7.  Security Considerations

   When interface identifiers (IIDs) are generated, devices and users
   are required to consider mitigating various threats, such as
   correlation of activities over time, location tracking, device-
   specific vulnerability exploitation, and address scanning.





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   IPv6-over-NFC is, in practice, not used for long-lived links for big
   size data transfer or multimedia streaming, but used for extremely
   short-lived links (i.e., single touch-based approaches) for ID
   verification and mobile payment.  This will mitigate the threat of
   correlation of activities over time.

   IPv6-over-NFC uses an IPv6 interface identifier formed from a "Short
   Address" and a set of well-known constant bits (such as padding with
   '0's) for the modified EUI-64 format.  However, the short address of
   NFC link layer (LLC) is not generated as a physically permanent value
   but logically generated for each connection.  Thus, every single
   touch connection can use a different short address of NFC link with
   an extremely short-lived link.  This can mitigate address scanning as
   well as location tracking and device-specific vulnerability
   exploitation.

   Thus, this document does not RECOMMEND sending NFC packets over the
   Internet or any unsecured network.

   If there is a compelling reason to send/receive the IPv6-over-NFC
   packets over the unsecured network, the deployment SHOULD make sure
   that the packets are sent over secured channels.  The particular
   Security mechanisms are out of scope of this document.

8.  Acknowledgements

   We are grateful to the members of the IETF 6lo working group.

   Michael Richardson, Suresh Krishnan, Pascal Thubert, Carsten Bormann,
   Alexandru Petrescu, James Woodyatt, Dave Thaler, Samita Chakrabarti,
   and Gabriel Montenegro have provided valuable feedback for this
   draft.

9.  References

9.1.  Normative References

   [LLCP-1.3]
              "NFC Logical Link Control Protocol version 1.3", NFC Forum
              Technical Specification , March 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.






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   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              DOI 10.17487/RFC3633, December 2003,
              <https://www.rfc-editor.org/info/rfc3633>.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, DOI 10.17487/RFC4291, February
              2006, <https://www.rfc-editor.org/info/rfc4291>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <https://www.rfc-editor.org/info/rfc4862>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <https://www.rfc-editor.org/info/rfc4944>.

   [RFC6282]  Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              DOI 10.17487/RFC6282, September 2011,
              <https://www.rfc-editor.org/info/rfc6282>.

   [RFC6775]  Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
              Bormann, "Neighbor Discovery Optimization for IPv6 over
              Low-Power Wireless Personal Area Networks (6LoWPANs)",
              RFC 6775, DOI 10.17487/RFC6775, November 2012,
              <https://www.rfc-editor.org/info/rfc6775>.

   [RFC7136]  Carpenter, B. and S. Jiang, "Significance of IPv6
              Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136,
              February 2014, <https://www.rfc-editor.org/info/rfc7136>.

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217,
              DOI 10.17487/RFC7217, April 2014,
              <https://www.rfc-editor.org/info/rfc7217>.







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   [RFC7400]  Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
              IPv6 over Low-Power Wireless Personal Area Networks
              (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
              2014, <https://www.rfc-editor.org/info/rfc7400>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [ECMA-340]
              "Near Field Communication - Interface and Protocol (NFCIP-
              1) 3rd Ed.", ECMA-340 , June 2013.

Authors' Addresses

   Younghwan Choi (editor)
   Electronics and Telecommunications Research Institute
   218 Gajeongno, Yuseung-gu
   Daejeon  34129
   Korea

   Phone: +82 42 860 1429
   Email: yhc@etri.re.kr


   Yong-Geun Hong
   Electronics and Telecommunications Research Institute
   161 Gajeong-Dong Yuseung-gu
   Daejeon  305-700
   Korea

   Phone: +82 42 860 6557
   Email: yghong@etri.re.kr


   Joo-Sang Youn
   DONG-EUI University
   176 Eomgwangno Busan_jin_gu
   Busan  614-714
   Korea

   Phone: +82 51 890 1993
   Email: joosang.youn@gmail.com






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   Dongkyun Kim
   Kyungpook National University
   80 Daehak-ro, Buk-gu
   Daegu  702-701
   Korea

   Phone: +82 53 950 7571
   Email: dongkyun@knu.ac.kr


   JinHyouk Choi
   Samsung Electronics Co.,
   129 Samsung-ro, Youngdong-gu
   Suwon  447-712
   Korea

   Phone: +82 2 2254 0114
   Email: jinchoe@samsung.com

































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