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
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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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publication of this document. Please review these documents
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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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