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Versions: 00 01 draft-ietf-6lowpan-btle

Individual Submission                                      B. Patil, Ed.
Internet-Draft                                             T. Savolainen
Intended status: Standards Track                             J. Nieminen
Expires: September 11, 2011                                   M. Isomaki
                                                                   Nokia
                                                               Z. Shelby
                                                               Sensinode
                                                          March 10, 2011


         Transmission of IPv6 Packets over Bluetooth Low Energy
                   draft-patil-6lowpan-v6over-btle-01

Abstract

   Bluetooth low energy is a low power air interface technology that is
   defined by the bluetooth 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 and enables the use of
   this air interface with devices such as sensors, smart meters,
   applicances, etc.  There is an added value in the ability to
   communicate with sensors over IPv6.  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 September 11, 2011.

Copyright Notice

   Copyright (c) 2011 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



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   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
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Bluetooth Low Energy protocol stack . . . . . . . . . . . . . . 4
     3.1.  Support for IPv6 over BT-LE . . . . . . . . . . . . . . . . 5
   4.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 6
   5.  Addressing Model  . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  MTU Issues  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  LowPan Adaptation for BLE and frame format  . . . . . . . . . . 7
   8.  IPv6 Address configuration  . . . . . . . . . . . . . . . . . . 7
   9.  IPv6 LLA in BLE . . . . . . . . . . . . . . . . . . . . . . . . 7
   10. Unicast and Multicast address mapping . . . . . . . . . . . . . 7
   11. Header compression  . . . . . . . . . . . . . . . . . . . . . . 7
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   13. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   14. Additional contributors . . . . . . . . . . . . . . . . . . . . 8
   15. Normative References  . . . . . . . . . . . . . . . . . . . . . 8
   Appendix A.  Bluetooth Low energy basics  . . . . . . . . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9




















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1.  Introduction

   Bluetooth Low Energy (BT-LE) is a radio technology targeted for
   devices that operate with coin cell batteries, which means that low
   power consumption is essential.  BT-LE can also be integrated into
   existing Bluetooth (BT) devices so that devices such as mobile phones
   and PCs can operate with existing BT accessories as well as BT-LE
   accessories.  An example of a use case for BT-LE accessory is a heart
   rate monitor that sends data via the mobile phone to a server on the
   Internet.  BT-LE is designed for transferring small amount of data
   (in most cases less than 10bytes) less frequently (e.g. every 500ms)
   at modest data rates (e.g. 300kbps).  BT-LE enables low cost sensors
   to send their data over the Internet via a gateway such as a mobile
   phone.  BT-LE is especially attractive technology for Internet of
   Things applications, such as health monitors, environmental sensing
   and proximity applications.

   Considering the expected explosion in the number of sensors, IPv6 is
   an ideal protocol due to the large address space it provides.  This
   document describes how IPv6 is used on Bluetooth Low Energy links in
   a power efficient manner along with efficient application protocols
   that enable the integration of BT-LE devices into services.

   [RFC4944] specifies the transmission of IPv6 over IEEE 802.15.4.  The
   bluetooth low energy link in many respects 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
   bluetooth low energy links.  This document specifies the details of
   IPv6 transmission over blue-tooth low energy links.


2.  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].

2.1.  Terminology

   Bluetooth Low Energy

      Bluetooth low energy is a low power air interface technology
      specified by the Bluetooth Special Interest Group (SIG).

   Bluetooth Network Encapsulation Protocol (BNEP)

      Define BNEP.




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   Gateway

      Network element connecting the BT-LE sensors to the Internet.  Can
      be e.g a home gateway or a mobile device.




   ND-Proxy

      A gateway that operates as a proxy for IPv6 neighbor discovery

   CoAP/HTTP Proxy

      A gateway that operates as a CoAP/HTTP proxy for the BT-LE
      sensors.  Link local addresses are used between the sensors and
      the CoAP/HTTP proxy

   6to4 prefix

      An IPv6 prefix constructed by combining well-known IPv6 prefix
      with public IPv4 address

   6to4/6RD router

      A router that has only IPv4 uplink connectivity and thus uses
      6to4/6RD prefix in the BT-LE network


3.  Bluetooth Low Energy protocol stack

   Bluetooth Low Energy is a low power wireless technology developed by
   the BT-SIG.  The lower layer of the BT-LE stack consists of the RF
   and the Link layer which are implemented in the BT-LE controller.
   The upper layer consists of the Logical Link Control and Adaptation
   Protocol (L2CAP), Generic Attribute protocol (GATT) and Generic
   Attribute 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 larger data
   packets.  Link Layer (LL) is responsible for managing the channels
   and Physical Layer (PHY) transmits and receives the actual packets.








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                  +----------------------------------------+
                  |              Applications              |
                  +----------------------------------------+
                  |          Generic Access Profile        |
                  +----------------------------------------+
                  |          Generic Attribute 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

3.1.  Support for IPv6 over BT-LE

   The Bluetooth Network Encapsulation Protocol (BNEP) has been
   developed for encapsulating any network protocol for Bluetooth L2CAP.
   BNEP assumes that L2CAP supports connection oriented channel.  Either
   a connection oriented channel needs to be added to the current BT-LE
   specification, over which BNEP, parts of 6LoWPAN, IPv6 and
   application protocols can be run or a new fixed channel ID may be
   reserved for BNEP traffic.  Figure 2 illustrates IPv6 over BT-LE
   stack.

   Constrained Application Protocol (CoAP) is an application protocol
   specifically designed for resource constrained environments.  CoAP
   could be run on top of IPv6 supporting requests from the server and
   requests of cached replies from a CoAP/HTTP proxy in the BT-LE
   gateway.














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                  +-------------------+
                  |  Applications     |
                  +-------------------+
                  |  CoAP/HTTP        |
                  +-------------------+
                  |  Compressed IPv6  |
                  +-------------------+
                  |  BNEP             |
                  +-------------------+
                  |  BT-LE L2CAP      |
                  +-------------------+
                  |  BT-LE Link Layer |
                  +-------------------+
                  |  BT-LE Physical   |
                  +-------------------+


                      Figure 2: IPv6 over BT-LE Stack


4.  Requirements

   BT-LE technology sets strict requirements for low power consumption
   and thus limits the allowed protocol overhead. 6LoWPAN standard
   [RFC4944] provides useful generic functionality like header
   compression, link-local IPv6 addresses, Neighbor Discovery and
   stateless IP-address autoconfiguration for reducing the overhead in
   802.15.4 networks.  This functionality can be partly applied to
   BT-LE.


5.  Addressing Model

   The link model of BLE needs to be considered and what kind of
   addressing is possible.


6.  MTU Issues

   Generally the sensors generate data that fits into one Link Layer
   packet (23 bytes) that is transferred to the collector periodically.
   IP data packets may be much larger and hence MTU size should be the
   size of the IP data packet.  Larger L2CAP packets can be transferred
   with the SAR feature of the Link Layer.  If an implementation cannot
   support the larger MTU size (due to cost) then SAR needs to be
   supported at upper layers.

   One option to support SAR would be to implement SAR functionality in



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   the BNEP layer.  Existing SAR functionality defined in [RFC4944]
   could also be used, taking into account BT-LE specific features such
   as different MTU in the L2CAP layer.


7.  LowPan Adaptation for BLE and frame format

   Transmission of IPv6 Packets over IEEE 802.15.4 Networks [RFC4944]
   defines an adaptation layer between IP and 802.15.4 radio networks.
   In these networks link layer does not support SAR functionality and
   thus IP packets must fit into the payload that is available in the
   127 octect long physical frame after variable size frame overhead has
   been added.  In BT-LE networks this kind of adaptation is not needed
   if SAR is supported in the Link Layer. is a


8.  IPv6 Address configuration

   SLAAC and other means to configure an address on a BLE device.
   Neighbor Discovery Optimization for Low-power and Lossy Networks
   [I-D.ietf-6lowpan-hc].  Might also add something about hard-coding
   well-known gateway or server addresses.


9.  IPv6 LLA in BLE

   Link local address format in BLE


10.  Unicast and Multicast address mapping

   Do we have to use multicast addresses in ultra low power network?  I
   dont know whether the same format specified for 802.15.4 can be
   reused.  Will need expert guidance here.


11.  Header compression

   Compression Format for IPv6 Datagrams in Low Power and Lossy Networks
   (6LoWPAN) [I-D.ietf-6lowpan-hc].

   In [RFC4944] different types of frame formats and related headers
   have been defined to support fragmentation and mesh addressing.  In
   BT-LE context LoWPAN_HC1 compressed IPv6 header would be used by
   default.  Support for fragmentation and mesh headers can be added if
   required.  In BT-LE link with header compression IPv6 header
   (originally 40 Bytes) can be compressed to only 2 Bytes with link-
   local addresses and 26 Bytes with Global addresses.  UDP header



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   (originally 8 Bytes) can be compressed to 4 Bytes.  IMO this section
   should be the same as with 6lowpan.


12.  IANA Considerations

   This document does not have any IANA requests at this time.  This may
   change with further development of the specification.


13.  Security Considerations

   The transmission of IPv6 over bluetooth low energy links has similar
   requirements and concerns for security as zigbee.  Security at the IP
   layer needs to be reviewed as part of the development of the IPv6
   over bluetooth low energy specification.


14.  Additional contributors

   Kanji Kerai and Jari Mutikainen from Nokia have contributed
   significantly to this document.


15.  Normative References

   [I-D.ietf-6lowpan-hc]
              Hui, J. and P. Thubert, "Compression Format for IPv6
              Datagrams in Low Power and Lossy Networks (6LoWPAN)",
              draft-ietf-6lowpan-hc-15 (work in progress),
              February 2011.

   [I-D.ietf-6lowpan-nd]
              Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor
              Discovery Optimization for Low-power and Lossy Networks",
              draft-ietf-6lowpan-nd-15 (work in progress),
              December 2010.

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

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

   [RFC4994]  Zeng, S., Volz, B., Kinnear, K., and J. Brzozowski,
              "DHCPv6 Relay Agent Echo Request Option", RFC 4994,
              September 2007.



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Appendix A.  Bluetooth Low energy basics

   This section will provide background material on the basics of
   bluetooth low energy.


Authors' Addresses

   Basavaraj Patil (editor)
   Nokia
   6021 Connection drive
   Irving, TX  75039
   USA

   Email: basavaraj.patil@nokia.com


   Teemu Savolainen
   Nokia
   Hermiankatu 12 D
   FI-33720 Tampere
   Finland

   Email: teemu.savolainen@nokia.com


   Johanna Nieminen
   Nokia
   Helsinki
   Finland

   Email: johanna.1.nieminen@nokia.com


   Markus Isomaki
   Nokia
   Espoo
   Finland

   Email: markus.isomaki@nokia.com


   Zach Shelby
   Sensinode







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