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Shelby 8 Sensinode 9 March 10, 2011 11 Transmission of IPv6 Packets over Bluetooth Low Energy 12 draft-patil-6lowpan-v6over-btle-01 14 Abstract 16 Bluetooth low energy is a low power air interface technology that is 17 defined by the bluetooth SIG. The standard bluetooth radio has been 18 widely implemented and available in mobile phones, notebook 19 computers, audio headsets and many other devices. The low power 20 version of bluetooth is a new specification and enables the use of 21 this air interface with devices such as sensors, smart meters, 22 applicances, etc. There is an added value in the ability to 23 communicate with sensors over IPv6. This document describes how IPv6 24 is transported over bluetooth low energy using 6LoWPAN techniques. 26 Status of this Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on September 11, 2011. 43 Copyright Notice 45 Copyright (c) 2011 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3 62 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Bluetooth Low Energy protocol stack . . . . . . . . . . . . . . 4 64 3.1. Support for IPv6 over BT-LE . . . . . . . . . . . . . . . . 5 65 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 5. Addressing Model . . . . . . . . . . . . . . . . . . . . . . . 6 67 6. MTU Issues . . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 7. LowPan Adaptation for BLE and frame format . . . . . . . . . . 7 69 8. IPv6 Address configuration . . . . . . . . . . . . . . . . . . 7 70 9. IPv6 LLA in BLE . . . . . . . . . . . . . . . . . . . . . . . . 7 71 10. Unicast and Multicast address mapping . . . . . . . . . . . . . 7 72 11. Header compression . . . . . . . . . . . . . . . . . . . . . . 7 73 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 74 13. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 75 14. Additional contributors . . . . . . . . . . . . . . . . . . . . 8 76 15. Normative References . . . . . . . . . . . . . . . . . . . . . 8 77 Appendix A. Bluetooth Low energy basics . . . . . . . . . . . . . 9 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 80 1. Introduction 82 Bluetooth Low Energy (BT-LE) is a radio technology targeted for 83 devices that operate with coin cell batteries, which means that low 84 power consumption is essential. BT-LE can also be integrated into 85 existing Bluetooth (BT) devices so that devices such as mobile phones 86 and PCs can operate with existing BT accessories as well as BT-LE 87 accessories. An example of a use case for BT-LE accessory is a heart 88 rate monitor that sends data via the mobile phone to a server on the 89 Internet. BT-LE is designed for transferring small amount of data 90 (in most cases less than 10bytes) less frequently (e.g. every 500ms) 91 at modest data rates (e.g. 300kbps). BT-LE enables low cost sensors 92 to send their data over the Internet via a gateway such as a mobile 93 phone. BT-LE is especially attractive technology for Internet of 94 Things applications, such as health monitors, environmental sensing 95 and proximity applications. 97 Considering the expected explosion in the number of sensors, IPv6 is 98 an ideal protocol due to the large address space it provides. This 99 document describes how IPv6 is used on Bluetooth Low Energy links in 100 a power efficient manner along with efficient application protocols 101 that enable the integration of BT-LE devices into services. 103 [RFC4944] specifies the transmission of IPv6 over IEEE 802.15.4. The 104 bluetooth low energy link in many respects has similar 105 characteristics to that of IEEE 802.15.4. Many of the mechanisms 106 defined in [RFC4944] can be applied to the transmission of IPv6 on 107 bluetooth low energy links. This document specifies the details of 108 IPv6 transmission over blue-tooth low energy links. 110 2. Requirements Language 112 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 113 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 114 document are to be interpreted as described in RFC 2119 [RFC2119]. 116 2.1. Terminology 118 Bluetooth Low Energy 120 Bluetooth low energy is a low power air interface technology 121 specified by the Bluetooth Special Interest Group (SIG). 123 Bluetooth Network Encapsulation Protocol (BNEP) 125 Define BNEP. 127 Gateway 129 Network element connecting the BT-LE sensors to the Internet. Can 130 be e.g a home gateway or a mobile device. 132 ND-Proxy 134 A gateway that operates as a proxy for IPv6 neighbor discovery 136 CoAP/HTTP Proxy 138 A gateway that operates as a CoAP/HTTP proxy for the BT-LE 139 sensors. Link local addresses are used between the sensors and 140 the CoAP/HTTP proxy 142 6to4 prefix 144 An IPv6 prefix constructed by combining well-known IPv6 prefix 145 with public IPv4 address 147 6to4/6RD router 149 A router that has only IPv4 uplink connectivity and thus uses 150 6to4/6RD prefix in the BT-LE network 152 3. Bluetooth Low Energy protocol stack 154 Bluetooth Low Energy is a low power wireless technology developed by 155 the BT-SIG. The lower layer of the BT-LE stack consists of the RF 156 and the Link layer which are implemented in the BT-LE controller. 157 The upper layer consists of the Logical Link Control and Adaptation 158 Protocol (L2CAP), Generic Attribute protocol (GATT) and Generic 159 Attribute profile (GAP) as shown in Figure 1. GATT and BT-LE 160 profiles together enable the creation of applications in a 161 standardized way without using IP. L2CAP provides multiplexing 162 capability by multiplexing the data channels from the above layers. 163 L2CAP also provides fragmentation and reassembly for larger data 164 packets. Link Layer (LL) is responsible for managing the channels 165 and Physical Layer (PHY) transmits and receives the actual packets. 167 +----------------------------------------+ 168 | Applications | 169 +----------------------------------------+ 170 | Generic Access Profile | 171 +----------------------------------------+ 172 | Generic Attribute Profile | 173 +----------------------------------------+ 174 | Attribute Protocol |Security Manager | 175 +--------------------+-------------------+ 176 | Logical Link Control and Adaptation | 177 +--------------------+-------------------+ 178 | Host Controller Interface | 179 +--------------------+-------------------+ 180 | Link Layer |Direct Test Mode | 181 +--------------------+-------------------+ 182 | Physical Layer | 183 +--------------------+-------------------+ 185 Figure 1: BT-LE Protocol Stack 187 3.1. Support for IPv6 over BT-LE 189 The Bluetooth Network Encapsulation Protocol (BNEP) has been 190 developed for encapsulating any network protocol for Bluetooth L2CAP. 191 BNEP assumes that L2CAP supports connection oriented channel. Either 192 a connection oriented channel needs to be added to the current BT-LE 193 specification, over which BNEP, parts of 6LoWPAN, IPv6 and 194 application protocols can be run or a new fixed channel ID may be 195 reserved for BNEP traffic. Figure 2 illustrates IPv6 over BT-LE 196 stack. 198 Constrained Application Protocol (CoAP) is an application protocol 199 specifically designed for resource constrained environments. CoAP 200 could be run on top of IPv6 supporting requests from the server and 201 requests of cached replies from a CoAP/HTTP proxy in the BT-LE 202 gateway. 204 +-------------------+ 205 | Applications | 206 +-------------------+ 207 | CoAP/HTTP | 208 +-------------------+ 209 | Compressed IPv6 | 210 +-------------------+ 211 | BNEP | 212 +-------------------+ 213 | BT-LE L2CAP | 214 +-------------------+ 215 | BT-LE Link Layer | 216 +-------------------+ 217 | BT-LE Physical | 218 +-------------------+ 220 Figure 2: IPv6 over BT-LE Stack 222 4. Requirements 224 BT-LE technology sets strict requirements for low power consumption 225 and thus limits the allowed protocol overhead. 6LoWPAN standard 226 [RFC4944] provides useful generic functionality like header 227 compression, link-local IPv6 addresses, Neighbor Discovery and 228 stateless IP-address autoconfiguration for reducing the overhead in 229 802.15.4 networks. This functionality can be partly applied to 230 BT-LE. 232 5. Addressing Model 234 The link model of BLE needs to be considered and what kind of 235 addressing is possible. 237 6. MTU Issues 239 Generally the sensors generate data that fits into one Link Layer 240 packet (23 bytes) that is transferred to the collector periodically. 241 IP data packets may be much larger and hence MTU size should be the 242 size of the IP data packet. Larger L2CAP packets can be transferred 243 with the SAR feature of the Link Layer. If an implementation cannot 244 support the larger MTU size (due to cost) then SAR needs to be 245 supported at upper layers. 247 One option to support SAR would be to implement SAR functionality in 248 the BNEP layer. Existing SAR functionality defined in [RFC4944] 249 could also be used, taking into account BT-LE specific features such 250 as different MTU in the L2CAP layer. 252 7. LowPan Adaptation for BLE and frame format 254 Transmission of IPv6 Packets over IEEE 802.15.4 Networks [RFC4944] 255 defines an adaptation layer between IP and 802.15.4 radio networks. 256 In these networks link layer does not support SAR functionality and 257 thus IP packets must fit into the payload that is available in the 258 127 octect long physical frame after variable size frame overhead has 259 been added. In BT-LE networks this kind of adaptation is not needed 260 if SAR is supported in the Link Layer. is a 262 8. IPv6 Address configuration 264 SLAAC and other means to configure an address on a BLE device. 265 Neighbor Discovery Optimization for Low-power and Lossy Networks 266 [I-D.ietf-6lowpan-hc]. Might also add something about hard-coding 267 well-known gateway or server addresses. 269 9. IPv6 LLA in BLE 271 Link local address format in BLE 273 10. Unicast and Multicast address mapping 275 Do we have to use multicast addresses in ultra low power network? I 276 dont know whether the same format specified for 802.15.4 can be 277 reused. Will need expert guidance here. 279 11. Header compression 281 Compression Format for IPv6 Datagrams in Low Power and Lossy Networks 282 (6LoWPAN) [I-D.ietf-6lowpan-hc]. 284 In [RFC4944] different types of frame formats and related headers 285 have been defined to support fragmentation and mesh addressing. In 286 BT-LE context LoWPAN_HC1 compressed IPv6 header would be used by 287 default. Support for fragmentation and mesh headers can be added if 288 required. In BT-LE link with header compression IPv6 header 289 (originally 40 Bytes) can be compressed to only 2 Bytes with link- 290 local addresses and 26 Bytes with Global addresses. UDP header 291 (originally 8 Bytes) can be compressed to 4 Bytes. IMO this section 292 should be the same as with 6lowpan. 294 12. IANA Considerations 296 This document does not have any IANA requests at this time. This may 297 change with further development of the specification. 299 13. Security Considerations 301 The transmission of IPv6 over bluetooth low energy links has similar 302 requirements and concerns for security as zigbee. Security at the IP 303 layer needs to be reviewed as part of the development of the IPv6 304 over bluetooth low energy specification. 306 14. Additional contributors 308 Kanji Kerai and Jari Mutikainen from Nokia have contributed 309 significantly to this document. 311 15. Normative References 313 [I-D.ietf-6lowpan-hc] 314 Hui, J. and P. Thubert, "Compression Format for IPv6 315 Datagrams in Low Power and Lossy Networks (6LoWPAN)", 316 draft-ietf-6lowpan-hc-15 (work in progress), 317 February 2011. 319 [I-D.ietf-6lowpan-nd] 320 Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor 321 Discovery Optimization for Low-power and Lossy Networks", 322 draft-ietf-6lowpan-nd-15 (work in progress), 323 December 2010. 325 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 326 Requirement Levels", BCP 14, RFC 2119, March 1997. 328 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 329 "Transmission of IPv6 Packets over IEEE 802.15.4 330 Networks", RFC 4944, September 2007. 332 [RFC4994] Zeng, S., Volz, B., Kinnear, K., and J. Brzozowski, 333 "DHCPv6 Relay Agent Echo Request Option", RFC 4994, 334 September 2007. 336 Appendix A. Bluetooth Low energy basics 338 This section will provide background material on the basics of 339 bluetooth low energy. 341 Authors' Addresses 343 Basavaraj Patil (editor) 344 Nokia 345 6021 Connection drive 346 Irving, TX 75039 347 USA 349 Email: basavaraj.patil@nokia.com 351 Teemu Savolainen 352 Nokia 353 Hermiankatu 12 D 354 FI-33720 Tampere 355 Finland 357 Email: teemu.savolainen@nokia.com 359 Johanna Nieminen 360 Nokia 361 Helsinki 362 Finland 364 Email: johanna.1.nieminen@nokia.com 366 Markus Isomaki 367 Nokia 368 Espoo 369 Finland 371 Email: markus.isomaki@nokia.com 373 Zach Shelby 374 Sensinode