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Versions: (draft-patil-6lowpan-v6over-btle) 00 01 02 03 04 05 06 07 08 09 10 11 12 draft-ietf-6lo-btle

6LoWPAN Working Group                                   J. Nieminen, Ed.
Internet-Draft                                        T. Savolainen, Ed.
Intended status: Standards Track                              M. Isomaki
Expires: August 16, 2013                                           Nokia
                                                                B. Patil

                                                               Z. Shelby
                                                               Sensinode
                                                                C. Gomez
                                              Universitat Politecnica de
                                                         Catalunya/i2CAT
                                                       February 12, 2013


         Transmission of IPv6 Packets over BLUETOOTH Low Energy
                       draft-ietf-6lowpan-btle-12

Abstract

   BLUETOOTH Low Energy is a low power air interface technology defined
   by the BLUETOOTH Special Interest Group (BT-SIG).  The standard
   BLUETOOTH radio has been widely implemented and available in mobile
   phones, notebook computers, audio headsets and many other devices.
   The low power version of BLUETOOTH is a new specification that
   enables the use of this air interface with devices such as sensors,
   smart meters, appliances, etc.  The low power variant of BLUETOOTH is
   currently specified in the revision 4.0 of the BLUETOOTH
   specifications (BLUETOOTH 4.0).  This document describes how IPv6 is
   transported over BLUETOOTH Low Energy 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 http://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 August 16, 2013.

Copyright Notice



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   Copyright (c) 2013 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
   (http://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
     1.1.  Terminology and Requirements Language  . . . . . . . . . .  3
   2.  BLUETOOTH Low Energy . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  BLUETOOTH Low Energy stack . . . . . . . . . . . . . . . .  4
     2.2.  Link layer roles and topology  . . . . . . . . . . . . . .  4
     2.3.  BT-LE device addressing  . . . . . . . . . . . . . . . . .  5
     2.4.  BT-LE packets sizes and MTU  . . . . . . . . . . . . . . .  5
   3.  Specification of IPv6 over BLUETOOTH Low Energy  . . . . . . .  6
     3.1.  Protocol stack . . . . . . . . . . . . . . . . . . . . . .  6
     3.2.  Link model . . . . . . . . . . . . . . . . . . . . . . . .  7
       3.2.1.  Stateless address autoconfiguration  . . . . . . . . .  8
       3.2.2.  Neighbor discovery . . . . . . . . . . . . . . . . . .  9
       3.2.3.  Header compression . . . . . . . . . . . . . . . . . .  9
       3.2.4.  Unicast and Multicast address mapping  . . . . . . . . 10
     3.3.  Internet connectivity scenarios  . . . . . . . . . . . . . 11
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.  Additional contributors  . . . . . . . . . . . . . . . . . . . 12
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Appendix A.  BLUETOOTH Low Energy fragmentation and L2CAP Modes  . 14
   Appendix B.  BLUETOOTH Low Energy L2CAP Channel ID Usage for
                6LoWPAN/IPv6  . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15









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1.  Introduction

   BLUETOOTH Low Energy (BT-LE) is a radio technology targeted for
   devices that operate with coin cell batteries or minimalistic power
   sources, which means that low power consumption is essential.  BT-LE
   is an especially attractive technology for Internet of Things
   applications, such as health monitors, environmental sensing,
   proximity applications and many others.

   Considering the potential for the exponential growth in the number of
   sensors and Internet connected devices and things, IPv6 is an ideal
   protocol due to the large address space it provides.  In addition,
   IPv6 provides tools for stateless address autoconfiguration, which is
   particularly suitable for sensor network applications and nodes which
   have very limited processing power or lack a full-fledged operating
   system.

   RFC 4944 [RFC4944] specifies the transmission of IPv6 over IEEE
   802.15.4.  The BT-LE link in many respects has similar
   characteristics to that of IEEE 802.15.4.  Many of the mechanisms
   defined in the RFC 4944 can be applied to the transmission of IPv6 on
   BT-LE links.  This document specifies the details of IPv6
   transmission over BT-LE links.

1.1.  Terminology and Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   The terms 6LN, 6LR and 6LBR are defined as in [RFC6775], with an
   addition that BT-LE master and BT-LE slave can both be either 6LN or
   6LBR.


2.  BLUETOOTH Low Energy

   BT-LE is designed for transferring small amounts of data infrequently
   at modest data rates at a very low cost per bit.  BLUETOOTH Special
   Interest Group has introduced two trademarks, BLUETOOTH Smart for
   single-mode devices (a device that only supports BT-LE) and BLUETOOTH
   Smart Ready for dual-mode devices.  In the rest of the draft, the
   term BT-LE refers to both types of devices.

   BT-LE is an integral part of the BT 4.0 specification [BTCorev4.0].
   Devices such as mobile phones, notebooks, tablets and other handheld
   computing devices which include BT 4.0 chipsets also have the low-
   energy functionality of BLUETOOTH.  BT-LE is also included in many



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   different types of accessories that collaborate with mobile devices
   such as phones, tablets and notebook computers.  An example of a use
   case for a BT-LE accessory is a heart rate monitor that sends data
   via the mobile phone to a server on the Internet.

2.1.  BLUETOOTH Low Energy stack

   The lower layer of the BT-LE stack consists of the Physical (PHY) and
   the Link Layer (LL).  The Physical Layer transmits and receives the
   actual packets.  The Link Layer is responsible for providing medium
   access, connection establishment, error control and flow control.
   The upper layer consists of the Logical Link Control and Adaptation
   Protocol (L2CAP), Generic Attribute protocol (GATT) and Generic
   Access Profile (GAP) as shown in Figure 1.  GATT and BT-LE profiles
   together enable the creation of applications in a standardized way
   without using IP.  L2CAP provides multiplexing capability by
   multiplexing the data channels from the above layers.  L2CAP also
   provides fragmentation and reassembly for large data packets.


       +----------------------------------------+------------------+
       |              Applications                                 |
       +----------------------------------------+------------------+
       |        Generic Attribute Profile       |  Generic Access  |
       +----------------------------------------+     Profile      |
       | Attribute Protocol |Security Manager   |                  |
       +--------------------+-------------------+------------------+
       |              Logical Link Control and Adaptation          |
       +--------------------+-------------------+------------------+
       |              Host Controller Interface                    |
       +--------------------+-------------------+------------------+
       |           Link Layer       |      Direct Test Mode        |
       +--------------------+-------------------+------------------+
       |              Physical Layer                               |
       +--------------------+-------------------+------------------+


                      Figure 1: BT-LE Protocol Stack

2.2.  Link layer roles and topology

   BT-LE defines two Link Layer roles: the BT-LE master role and the
   BT-LE slave role.  A device in the master role, which is called
   master from now on, can manage multiple simultaneous connections with
   a number of devices in the slave role, called slaves from now on.  A
   slave can only be connected to a single master.  Hence, a BT-LE
   network (i.e. a BT-LE piconet) follows a star topology shown in the
   Figure 2.  This specification primarily addresses the situation where



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   the slave is a 6LN but not a 6LBR at the IPv6 level.


          [BT-LE slave]-----\                  /-----[BT-LE slave]
                             \                /
            [BT-LE slave]-----+[BT-LE Master]+-----[BT-LE slave]
                             /                \
          [BT-LE slave]-----/                  \-----[BT-LE slave]



                       Figure 2: BT-LE Star Topology

   A master is assumed to be less constrained than a slave.  Hence, in
   the primary scenario master and slave will act as 6LoWPAN Border
   Router (6LBR) and a 6LoWPAN Node (6LN), respectively.

   In BT-LE, communication only takes place between a master and a
   slave.  Hence, in a BT-LE network using IPv6, a radio hop is
   equivalent to an IPv6 link and vice versa.

2.3.  BT-LE device addressing

   Every BT-LE device is identified by a 48-bit device address.  The
   BLUETOOTH specification describes the device address of a BTLE device
   as:"Devices are identified using a device address.  Device addresses
   may be either a public device address or a random device address."
   [BTCorev4.0].  The public device addresses are based on the IEEE 802-
   2001 standard [IEEE802-2001].  The random device addresses are
   generated as defined in the BLUETOOTH specification.  The device
   addresses are always unique within a BT-LE piconet, but the random
   addresses are not guaranteed to be globally unique.

2.4.  BT-LE packets sizes and MTU

   Maximum size of the payload in the BT-LE data channel PDU is 27
   bytes.  Depending on the L2CAP mode in use, the amount of data
   available for transporting bytes in the single BT-LE data channel PDU
   ranges between 19 and 27 octets.  For power efficient communication
   between two BT-LE nodes, data and its header should fit in a single
   BT-LE data channel PDU.  However, IPv6 requires support for an MTU of
   1280 bytes.  An inherent function of the BT-LE L2CAP layer, called
   Fragmentation and Recombination (FAR), can assist in transferring
   IPv6 packets that do not fit in a single BT-LE data channel PDU.

   The maximum IPv6 datagram size that can be transported by L2CAP
   depends on the L2CAP mode.  The Basic L2CAP Mode allows a maximum
   payload size (i.e.  IPv6 datagram size) of 65535 bytes per L2CAP PDU.



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   The rest of the L2CAP modes allow a maximum payload size that ranges
   between 65527 and 65533 bytes per L2CAP PDU.  Appendix A describes
   FAR operation and five L2CAP Modes.


3.  Specification of IPv6 over BLUETOOTH Low Energy

   BT-LE technology sets strict requirements for low power consumption
   and thus limits the allowed protocol overhead. 6LoWPAN standards
   [RFC4944], [RFC6775], and [RFC6282] provide useful functionality for
   reducing overhead which can be applied to BT-LE.  This functionality
   comprises of link-local IPv6 addresses and stateless IPv6 address
   autoconfiguration (see Section 3.2.1), Neighbor Discovery (see
   Section 3.2.2) and header compression (see Section 3.2.3).

   A significant difference between IEEE 802.15.4 and BT-LE is that the
   former supports both star and mesh topology (and requires a routing
   protocol), whereas BT-LE does not currently support the formation of
   multihop networks at the link layer.  In consequence, the mesh header
   defined in [RFC4944] for mesh under routing MUST NOT be used in BT-LE
   networks.  In addition, a BT-LE node MUST NOT play the role of a
   6LoWPAN Router (6LR).

3.1.  Protocol stack

   In order to enable transmission of IPv6 packets over BT-LE, a new
   fixed L2CAP Channel Identifier (Channel ID) is to be reserved for
   IPv6 traffic by the BT-SIG.  Until the Channel ID is reserved,
   prototype implementations can be implemented as is described in the
   Appendix B.

   Figure 3 illustrates IPv6 over BT-LE stack.  UDP and TCP are provided
   as examples of transport protocols, but the stack can be used by any
   other upper layer protocol capable of running atop of IPv6.

















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                      +----------------------------+
                      |       UDP/TCP/other        |
                      +----------------------------+
                      |            IPv6            |
                      +----------------------------+
                      |  6LoWPAN adapted to BT-LE  |
                      +----------------------------+
                      |        BT-LE L2CAP         |
                      +----------------------------+
                      |      BT-LE Link Layer      |
                      +----------------------------+
                      |       BT-LE Physical       |
                      +----------------------------+

                      Figure 3: IPv6 over BT-LE Stack

3.2.  Link model

   The concept of IPv6 link (layer 3) and the physical link (combination
   of PHY and MAC) needs to be clear and the relationship has to be well
   understood in order to specify the addressing scheme for transmitting
   IPv6 packets over the BT-LE link.  RFC 4861 [RFC4861] defines a link
   as "a communication facility or medium over which nodes can
   communicate at the link layer, i.e., the layer immediately below
   IPv6."

   In the case of BT-LE, L2CAP is an adaptation layer that supports the
   transmission of IPv6 packets.  L2CAP also provides multiplexing
   capability in addition to FAR functionality.  This specification
   requires that FAR functionality MUST be provided in the L2CAP layer.
   The L2CAP channel characteristics for the transmission of IPv6
   packets on top of BT-LE are the following:

   MTU: Equal to or greater than 1280 bytes

   Flush Timeout: 0xFFFF (Infinite)

   QoS: Best Effort

   Mode: Basic Mode

   Since FAR in BT-LE is a function of the L2CAP layer, fragmentation
   functionality as defined in RFC 4944 [RFC4944] MUST NOT be used in
   BT-LE networks.  This specification also assumes the IPv6 header
   compression format specified in RFC 6282 [RFC6282].  It is also
   assumed that the IPv6 payload length can be inferred from the L2CAP
   header length and the IID value inferred, with help of Neighbor
   Cache, from the link-layer address.



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   The BT-LE link between two communicating nodes can be considered to
   be a point-to-point or point-to-multipoint link.  When one of the
   communicating nodes is in the role of a master, then the link can be
   viewed as a point-to-multipoint link from the master point of view.
   However, due to BT-LE star topology, each branch of the star is
   considered to be an individual link and thus the slaves cannot
   directly hear each other and also cannot talk to each other with
   link-local addresses.  The master ensures address collisions do not
   occur (see Section 3.2.2).

   After the slave and master have connected at the BT-LE level, the
   link can be considered up and IPv6 address configuration and
   transmission can begin.

3.2.1.  Stateless address autoconfiguration

   A BT-LE 6LN performs stateless address autoconfiguration as per RFC
   4862 [RFC4862].  A 64-bit Interface identifier (IID) for a BT-LE
   interface MAY be formed by utilizing the 48-bit BLUETOOTH device
   address (see Section 2.3) as defined in RFC 2464 "IPv6 over Ethernet"
   specification [RFC2464].  Alternatively, a randomly generated IID
   (see Section 3.2.2), MAY be used instead.  In the case of randomly
   generated IID or randomly generated BLUETOOTH device address, the
   "Universal/Local" bit MUST be set to 0 [RFC4291].  Only if the
   BLUETOOTH device address is known to be a public address the
   "Universal/Local" bit can be set to 1.

   As defined in RFC 4291 [RFC4291], the IPv6 link-local address for a
   BT-LE node is formed by appending the IID, to the prefix FE80::/64,
   as depicted in Figure 4.


             10 bits        54 bits             64 bits
           +----------+-----------------+----------------------+
           |1111111010|       zeros     | Interface Identifier |
           +----------+-----------------+----------------------+


                Figure 4: IPv6 link-local address in BT-LE

   The tool for a 6LBR to obtain an IPv6 prefix for numbering the BT-LE
   network is out of scope of this document, but can be, for example,
   accomplished via DHCPv6 Prefix Delegation [RFC3633] or by using
   Unique Local IPv6 Unicast Addresses (ULA) [RFC4193].  Due to the link
   model of the BT-LE (see Section 2.2) the 6LBR MUST set the "on-link"
   flag (L) to zero in the Prefix Information Option [RFC4861].  This
   will cause 6LNs to always send packets to the 6LBR, including the
   case when the destination is another 6LN using the same prefix.



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3.2.2.  Neighbor discovery

   'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
   Personal Area Networks (6LoWPANs)' [RFC6775] describes the neighbor
   discovery approach as adapted for use in several 6LoWPAN topologies,
   including the mesh topology.  BT-LE does not support mesh networks
   and hence only those aspects that apply to a star topology are
   considered.

   The following aspects of the Neighbor Discovery optimizations
   [RFC6775] are applicable to BT-LE 6LNs:

   1.  A BT-LE 6LN MUST register its address with the 6LBR by sending a
   Neighbor Solicitation (NS) message with the ARO option and process
   the Neighbor Advertisement (NA) accordingly.  The NS with the ARO
   option SHOULD be sent irrespective of whether the IID is derived from
   the unique 48 bit BT-LE device address or the IID is a random value
   that is generated as per the privacy extensions for stateless address
   autoconfiguration [RFC4941].  Although RFC 4941 [RFC4941] permits the
   use of deprecated addresses for old connections, in this
   specification we mandate that one interface MUST NOT use more than
   one IID at any one time.

   2.  For sending Router Solicitations and processing Router
   Advertisements the BT-LE 6LNs MUST, respectively, follow Sections 5.3
   and 5.4 of the [RFC6775].

3.2.3.  Header compression

   Header compression as defined in RFC 6282 [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 BT-LE.  All headers MUST be compressed according to RFC 6282
   [RFC6282] encoding formats.  The BT-LE's star topology structure can
   be exploited in order to provide a mechanism for IID compression.
   The following text describes the principles of IPv6 address
   compression on top of BT-LE.

   In a link-local communication, both the IPv6 source and destination
   addresses MUST be elided [RFC6282], since the node knows that the
   packet is destined for it even if the packet does not have
   destination IPv6 address.  On the other hand, a node SHALL learn the
   IID of the other endpoint of each L2CAP connection it participates
   in.  By exploiting this information, a node that receives a data
   channel PDU containing an IPv6 packet (or a part of it) can infer the
   corresponding IPv6 source address.  A node MUST maintain a Neighbor
   Cache, in which the entries include both the IID of the neighbor and
   the Device Address that identifies the neighbor.  For the type of



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   communication considered in this paragraph, the following settings
   MUST be used in the IPv6 compressed header: CID=0, SAC=0, SAM=11,
   DAC=0, DAM=11.

   When a 6LN transmits an IPv6 packet to a remote destination using
   global Unicast IPv6 addresses, if a context is defined for the prefix
   of the 6LNs global IPv6 address, the 6LN MUST indicate this context
   in the corresponding source fields of the compressed IPv6 header as
   per Section 3.1 of RFC 6282 [RFC6282], and MUST elide the IPv6 source
   address.  For this, the 6LN MUST use the following settings in the
   IPv6 compressed header: CID=1, SAC=1, SAM=11.  In this case, the 6LBR
   can infer the elided IPv6 source address since 1) the 6LBR has
   previously assigned the prefix to the 6LNs; and 2) the 6LBR maintains
   a Neighbor Cache that relates the Device Address and the IID of the
   corresponding slave.  If a context is defined for the IPv6
   destination address, the 6LN MUST also indicate this context in the
   corresponding destination fields of the compressed IPv6 header, and
   MUST elide the prefix of the destination IPv6 address.  For this, the
   6LN MUST set the DAM field of the compressed IPv6 header as DAM=01
   (if the context covers a 64-bit prefix) or as DAM=11 (if the context
   covers a full, 128-bit address).  CID and DAC MUST be set to CID=1
   and DAC=1.  Note that when a context is defined for the IPv6
   destination address, the 6LBR can infer the elided destination prefix
   by using the context.

   When a 6LBR receives an IPv6 packet sent by a remote node outside the
   BT-LE network, and the destination of the packet is a 6LN, if a
   context is defined for the prefix of the 6LN's global IPv6 address,
   the 6LBR MUST indicate this context in the corresponding destination
   fields of the compressed IPv6 header, and MUST elide the IPv6
   destination address of the packet before forwarding it to the 6LN.
   For this, the 6LBR MUST set the DAM field of the IPv6 compressed
   header as DAM=11.  CID and DAC MUST be set to CID=1 and DAC=1.  If a
   context is defined for the prefix of the IPv6 source address, the
   6LBR MUST indicate this context in the source fields of the
   compressed IPv6 header, and MUST elide that prefix as well.  For
   this, the 6LBR MUST set the SAM field of the IPv6 compressed header
   as SAM=01 (if the context covers a 64-bit prefix) or SAM=11 (if the
   context covers a full, 128-bit address).  CID and SAC MUST be set to
   CID=1 and SAC=1.

3.2.4.  Unicast and Multicast address mapping

   The BT-LE link layer does not support multicast.  Hence traffic is
   always unicast between two BT-LE nodes.  Even in the case where a
   master is attached to multiple slaves, the master cannot do a
   multicast to all the connected slaves.  If the master needs to send a
   multicast packet to all its slaves, it has to replicate the packet



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   and unicast it on each link.  However, this may not be energy-
   efficient and particular care must be taken if the master is battery-
   powered.  In the opposite direction, a slave can only transmit data
   to a single destination (i.e. the master).  Hence, when a slave needs
   to transmit an IPv6 multicast packet, the slave will unicast the
   corresponding BT-LE packet to the master.  As described in the
   Section 3.2 the master will not forward link-local multicast messages
   to other slaves connected to the master.

3.3.  Internet connectivity scenarios

   In a typical scenario, the BT-LE network is connected to the Internet
   as shown in the Figure 5.

   A degenerate scenario can be imagined where a slave is acting as 6LBR
   and providing Internet connectivity for the master.  How the master
   could then further provide Internet connectivity to other slaves,
   possibly connected to the master, is out of the scope of this
   document.



                         6LN
                          \            ____________
                           \          /            \
                   6LN ---- 6LBR --- |  Internet   |
                           /          \____________/
                          /
                         6LN

                   <-- BT-LE -->


             Figure 5: BT-LE network connected to the Internet

   In some scenarios, the BT-LE network may transiently or permanently
   be an isolated network as shown in the Figure 6.


                        6LN      6LN
                         \      /
                          \    /
                   6LN --- 6LBR --- 6LN
                          /    \
                         /      \
                        6LN      6LN

                   <------ BT-LE ----->



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                     Figure 6: Isolated BT-LE network

   In the isolated network scenario communications between 6LN and 6LBR
   can use IPv6 link-local methodology, but for communications between
   different slaves, the master has to act as 6LBR, number the network
   with ULA prefix [RFC4193], and route packets between slaves.


4.  IANA Considerations

   There are no IANA considerations related to this document.


5.  Security Considerations

   The transmission of IPv6 over BT-LE links has similar requirements
   and concerns for security as for IEEE 802.15.4.  IPv6 over BT-LE
   SHOULD be protected by using BT-LE Link Layer security.

   BT-LE Link Layer supports encryption and authentication by using the
   Counter with CBC-MAC (CCM) mechanism [RFC3610] and a 128-bit AES
   block cipher.  Upper layer security mechanisms may exploit this
   functionality when it is available.  (Note: CCM does not consume
   bytes from the maximum per-packet L2CAP data size, since the link
   layer data unit has a specific field for them when they are used.)

   Key management in BT-LE is provided by the Security Manager Protocol
   (SMP), as defined in [BTCorev4.0].


6.  Additional contributors

   Kanji Kerai, Jari Mutikainen, David Canfeng-Chen and Minjun Xi from
   Nokia have contributed significantly to this document.


7.  Acknowledgements

   The BLUETOOTH, BLUETOOTH Smart and BLUETOOTH Smart Ready marks are
   registred trademarks owned by BLUETOOTH SIG, Inc.

   Samita Chakrabarti, Erik Nordmark, and Marcel De Kogel have provided
   valuable feedback for this draft.


8.  References





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8.1.  Normative References

   [BTCorev4.0]
              BLUETOOTH Special Interest Group, "BLUETOOTH Specification
              Version 4.0", June 2010.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, December 1998.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, September 2007.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, September 2007.

   [RFC6282]  Hui, J. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              September 2011.

   [RFC6775]  Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
              "Neighbor Discovery Optimization for IPv6 over Low-Power
              Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
              November 2012.

8.2.  Informative References

   [IEEE802-2001]
              Institute of Electrical and Electronics Engineers (IEEE),
              "IEEE 802-2001 Standard for Local and Metropolitan Area
              Networks: Overview and Architecture", 2002.

   [RFC3610]  Whiting, D., Housley, R., and N. Ferguson, "Counter with
              CBC-MAC (CCM)", RFC 3610, September 2003.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.



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   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for Stateless Address Autoconfiguration in
              IPv6", RFC 4941, September 2007.


Appendix A.  BLUETOOTH Low Energy fragmentation and L2CAP Modes

   This section provides an overview of Fragmentation and Recombination
   (FAR) method and L2CAP modes in BT-LE.  FAR is an L2CAP mechanism, in
   which an L2CAP entity can take the (large) upper layer PDU, prepend
   the L2CAP header (4 bytes in the Basic L2CAP mode) and break the
   resulting L2CAP PDU into fragments which can then be directly
   encapsulated into Data channel PDUs.  There are bits in the Data
   channel PDUs which identify whether the payload is a complete L2CAP
   PDU or the first of a set of fragments, or one of the rest of the
   fragments.

   There are five L2CAP modes defined in the BT 4.0 spec.  These modes
   are: Retransmission Mode (a Go-Back-N mechanism is used), Enhanced
   Retransmission Mode (includes selective NAK among others), Flow
   Control Mode (PDUs are numbered, but there are no retransmissions),
   Streaming Mode (PDUs are numbered, but there are no ACKs of any kind)
   and Basic L2CAP Mode.


Appendix B.  BLUETOOTH Low Energy L2CAP Channel ID Usage for 6LoWPAN/
             IPv6

   The BT-LE Logical Link Control and Adaptation Protocol (L2CAP) uses
   Channel Identifiers (IDs) to distinguish the upper layer protocol
   carried on top of it.  Two devices exchanging IPv6/6LoWPAN packets
   need to use a common Channel ID to be able to send and receive the
   packets correctly over L2CAP.  It is also important that they avoid
   using Channel ID's that conflict with other L2CAP usages.  For the
   initial use of IPv6/6LoWPAN over BT-LE L2CAP, implementers are
   recommended to use Channel ID 0x3E from the BLUETOOTH Special
   Interest Group reserved space (BLUETOOTH 4.0 Logical Link Control and
   Adaptation Protocol Specification -part, table 2.1 [BTCorev4.0]).  As
   the IPv6/6LoWPAN use becomes more widely adopted, the BT SIG may
   allocate 0x3E or some other Channel ID exclusively for IPv6/6LoWPAN.
   Any such BT SIG allocation will deprecate the recommendation given in
   this Appendix, and a new RFC will be published at the time of
   allocation that will update this RFC and specify the allocated value.
   The initial implementers are thus recommended to keep their Channel
   ID usage capability flexible to potential future changes.



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Authors' Addresses

   Johanna Nieminen (editor)
   Nokia
   Itaemerenkatu 11-13
   FI-00180 Helsinki
   Finland

   Email: johannamaria.nieminen@gmail.com


   Teemu Savolainen (editor)
   Nokia
   Hermiankatu 12 D
   FI-33720 Tampere
   Finland

   Email: teemu.savolainen@nokia.com


   Markus Isomaki
   Nokia
   Keilalahdentie 2-4
   FI-02150 Espoo
   Finland

   Email: markus.isomaki@nokia.com


   Basavaraj Patil
   6021 Connection drive
   Irving, TX  75039
   USA

   Email: bpatil@ovi.com


   Zach Shelby
   Sensinode
   Hallituskatu 13-17D
   FI-90100 Oulu
   Finland

   Email: zach.shelby@sensinode.com







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   Carles Gomez
   Universitat Politecnica de Catalunya/i2CAT
   C/Esteve Terradas, 7
   Castelldefels  08860
   Spain

   Email: carlesgo@entel.upc.edu












































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