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 Patil, et al. Expires September 11, 2011 [Page 1] Internet-Draft IPv6 over BT-LE March 2011 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 Patil, et al. Expires September 11, 2011 [Page 2] Internet-Draft IPv6 over BT-LE March 2011 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. Patil, et al. Expires September 11, 2011 [Page 3] Internet-Draft IPv6 over BT-LE March 2011 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. Patil, et al. Expires September 11, 2011 [Page 4] Internet-Draft IPv6 over BT-LE March 2011 +----------------------------------------+ | 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. Patil, et al. Expires September 11, 2011 [Page 5] Internet-Draft IPv6 over BT-LE March 2011 +-------------------+ | 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 Patil, et al. Expires September 11, 2011 [Page 6] Internet-Draft IPv6 over BT-LE March 2011 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 Patil, et al. Expires September 11, 2011 [Page 7] Internet-Draft IPv6 over BT-LE March 2011 (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. Patil, et al. Expires September 11, 2011 [Page 8] Internet-Draft IPv6 over BT-LE March 2011 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 Patil, et al. Expires September 11, 2011 [Page 9]