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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'IPSP' == Outdated reference: A later version (-16) exists of draft-ietf-6man-default-iids-02 -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) -- Obsolete informational reference (is this intentional?): RFC 3633 (Obsoleted by RFC 8415) -- Obsolete informational reference (is this intentional?): RFC 4941 (Obsoleted by RFC 8981) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 5 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6Lo Working Group J. Nieminen 3 Internet-Draft T. Savolainen 4 Intended status: Standards Track M. Isomaki 5 Expires: October 29, 2015 Nokia 6 B. Patil 7 AT&T 8 Z. Shelby 9 Arm 10 C. Gomez 11 Universitat Politecnica de Catalunya/i2CAT 12 April 27, 2015 14 IPv6 over BLUETOOTH(R) Low Energy 15 draft-ietf-6lo-btle-11 17 Abstract 19 Bluetooth Smart is the brand name for the Bluetooth low energy 20 feature in the Bluetooth specification defined by the Bluetooth 21 Special Interest Group. The standard Bluetooth radio has been widely 22 implemented and available in mobile phones, notebook computers, audio 23 headsets and many other devices. The low power version of Bluetooth 24 is a specification that enables the use of this air interface with 25 devices such as sensors, smart meters, appliances, etc. The low 26 power variant of Bluetooth is standardized since the revision 4.0 of 27 the Bluetooth specifications, although version 4.1 or newer is 28 required for IPv6. This document describes how IPv6 is transported 29 over Bluetooth low energy using 6LoWPAN techniques. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on October 29, 2015. 48 Copyright Notice 50 Copyright (c) 2015 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 1.1. Terminology and Requirements Language . . . . . . . . . . 3 67 2. Bluetooth Low Energy . . . . . . . . . . . . . . . . . . . . 3 68 2.1. Bluetooth LE stack . . . . . . . . . . . . . . . . . . . 4 69 2.2. Link layer roles and topology . . . . . . . . . . . . . . 5 70 2.3. Bluetooth LE device addressing . . . . . . . . . . . . . 5 71 2.4. Bluetooth LE packets sizes and MTU . . . . . . . . . . . 5 72 3. Specification of IPv6 over Bluetooth Low Energy . . . . . . . 6 73 3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . 7 74 3.2. Link model . . . . . . . . . . . . . . . . . . . . . . . 7 75 3.2.1. Stateless address autoconfiguration . . . . . . . . . 8 76 3.2.2. Neighbor discovery . . . . . . . . . . . . . . . . . 10 77 3.2.3. Header compression . . . . . . . . . . . . . . . . . 10 78 3.2.3.1. Remote destination example . . . . . . . . . . . 11 79 3.2.4. Unicast and Multicast address mapping . . . . . . . . 12 80 3.3. Subnets and Internet connectivity scenarios . . . . . . . 13 81 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 82 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 83 6. Additional contributors . . . . . . . . . . . . . . . . . . . 14 84 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 85 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 86 8.1. Normative References . . . . . . . . . . . . . . . . . . 15 87 8.2. Informative References . . . . . . . . . . . . . . . . . 16 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 90 1. Introduction 92 Bluetooth low energy (LE) is a radio technology targeted for devices 93 that operate with coin cell batteries or minimalistic power sources, 94 which means that low power consumption is essential. Bluetooth LE is 95 especially attractive technology for Internet of Things applications, 96 such as health monitors, environmental sensing, proximity 97 applications and many others. 99 Considering the potential for the exponential growth in the number of 100 sensors and Internet connected devices, IPv6 is an ideal protocol due 101 to the large address space it provides. In addition, IPv6 provides 102 tools for stateless address autoconfiguration, which is particularly 103 suitable for sensor network applications and nodes which have very 104 limited processing power or lack a full-fledged operating system. 106 RFC 4944 [RFC4944] specifies the transmission of IPv6 over IEEE 107 802.15.4. The Bluetooth LE link in many respects has similar 108 characteristics to that of IEEE 802.15.4. Many of the mechanisms 109 defined in the RFC 4944 can be applied to the transmission of IPv6 on 110 Bluetooth LE links. This document specifies the details of IPv6 111 transmission over Bluetooth LE links. 113 1.1. Terminology and Requirements Language 115 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 116 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 117 document are to be interpreted as described in RFC 2119 [RFC2119]. 119 The terms 6LN, 6LR and 6LBR are defined as in [RFC6775], with an 120 addition that Bluetooth LE central and Bluetooth LE peripheral (see 121 Section 2.2) can both be either 6LN or 6LBR. 123 2. Bluetooth Low Energy 125 Bluetooth LE is designed for transferring small amounts of data 126 infrequently at modest data rates at a very low cost per bit. 127 Bluetooth Special Interest Group (Bluetooth SIG) has introduced two 128 trademarks, Bluetooth Smart for single-mode devices (a device that 129 only supports Bluetooth LE) and Bluetooth Smart Ready for dual-mode 130 devices (devices that support both Bluetooth and Bluetooth LE). In 131 the rest of the document, the term Bluetooth LE refers to both types 132 of devices. 134 Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth 135 4.1 [BTCorev4.1], and developed even further in successive versions. 136 Bluetooth SIG has also published Internet Protocol Support Profile 137 (IPSP) [IPSP], which includes Internet Protocol Support Service 138 (IPSS). The IPSP enables discovery of IP-enabled devices and 139 establishment of link-layer connection for transporting IPv6 packets. 140 IPv6 over Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 141 1.0 or newer. 143 Devices such as mobile phones, notebooks, tablets and other handheld 144 computing devices which will include Bluetooth 4.1 chipsets will also 145 have the low-energy functionality of Bluetooth. Bluetooth LE will 146 also be included in many different types of accessories that 147 collaborate with mobile devices such as phones, tablets and notebook 148 computers. An example of a use case for a Bluetooth LE accessory is 149 a heart rate monitor that sends data via the mobile phone to a server 150 on the Internet. 152 2.1. Bluetooth LE stack 154 The lower layer of the Bluetooth LE stack consists of the Physical 155 (PHY) and the Link Layer (LL). The Physical Layer transmits and 156 receives the actual packets. The Link Layer is responsible for 157 providing medium access, connection establishment, error control and 158 flow control. The upper layer consists of the Logical Link Control 159 and Adaptation Protocol (L2CAP), Attribute Protocol (ATT), Generic 160 Attribute Profile (GATT) and Generic Access Profile (GAP) as shown in 161 Figure 1. The device internal Host Controller Interface (HCI) 162 separates the lower layers, often implemented in the Bluetooth 163 controller, from higher layers, often implemented in the host stack. 164 GATT and Bluetooth LE profiles together enable the creation of 165 applications in a standardized way without using IP. L2CAP provides 166 multiplexing capability by multiplexing the data channels from the 167 above layers. L2CAP also provides fragmentation and reassembly for 168 large data packets. 170 +-------------------------------------------------+ 171 | Applications | 172 +---------------------------------------+---------+ 173 | Generic Attribute Profile | Generic | 174 +--------------------+------------------+ Access | 175 | Attribute Protocol | Security Manager | Profile | 176 +--------------------+------------------+---------+ 177 | Logical Link Control and Adaptation Protocol | 178 - - -+-----------------------+-------------------------+- - - HCI 179 | Link Layer | Direct Test Mode | 180 +-------------------------------------------------+ 181 | Physical Layer | 182 +-------------------------------------------------+ 184 Figure 1: Bluetooth LE Protocol Stack 186 2.2. Link layer roles and topology 188 Bluetooth LE defines two GAP roles of relevance herein: the Bluetooth 189 LE central role and the Bluetooth LE peripheral role. A device in 190 the central role, which is called central from now on, has 191 traditionally been able to manage multiple simultaneous connections 192 with a number of devices in the peripheral role, called peripherals 193 from now on. A peripheral is commonly connected to a single central, 194 but since Bluetooth 4.1 can also connect to multiple centrals. In 195 this document for IPv6 networking purposes the Bluetooth LE network 196 (i.e. a Bluetooth LE piconet) follows a star topology shown in the 197 Figure 2, where the router typically implements the Bluetooth LE 198 central role and nodes implement the Bluetooth LE peripheral role. 199 In the future mesh networking may be defined for IPv6 over Bluetooth 200 LE. 202 Peripheral --. .-- Peripheral 203 \ / 204 Peripheral ---- Central ---- Peripheral 205 / \ 206 Peripheral --' '-- Peripheral 208 Figure 2: Bluetooth LE Star Topology 210 In Bluetooth LE, direct communication only takes place between a 211 central and a peripheral. This means that inherently the Bluetooth 212 LE star represents a hub and spokes link model. 214 2.3. Bluetooth LE device addressing 216 Every Bluetooth LE device is identified by a 48-bit device address. 217 The Bluetooth specification describes the device address of a 218 Bluetooth LE device as:"Devices are identified using a device 219 address. Device addresses may be either a public device address or a 220 random device address." [BTCorev4.1]. The public device addresses 221 are based on the IEEE 802-2001 standard [IEEE802-2001]. The random 222 device addresses are generated as defined in the Bluetooth 223 specification. This typically happens at every power cycle of a 224 device. In random addresses all 48 bits are randomized. Bluetooth 225 LE does not support device address collision avoidance or detection. 226 However, these 48 bit random device addresses have a very small 227 probability of being in conflict within a typical deployment. 229 2.4. Bluetooth LE packets sizes and MTU 231 Optimal MTU defined for L2CAP fixed channels over Bluetooth LE is 27 232 bytes including the L2CAP header of four bytes. Default MTU for 233 Bluetooth LE is hence defined to be 27 bytes. Therefore, excluding 234 L2CAP header of four bytes, protocol data unit (PDU) size of 23 bytes 235 is available for upper layers. In order to be able to transmit IPv6 236 packets of 1280 bytes or larger, link layer fragmentation and 237 reassembly solution is provided by the L2CAP layer. The IPSP defines 238 means for negotiating up a link-layer connection that provides MTU of 239 1280 bytes or higher for the IPv6 layer [IPSP]. The link-layer MTU 240 is negotiated separately for each direction. Implementations that 241 require single link-layer MTU value SHALL use the smallest of the 242 possibly different MTU values. 244 3. Specification of IPv6 over Bluetooth Low Energy 246 Bluetooth LE technology sets strict requirements for low power 247 consumption and thus limits the allowed protocol overhead. 6LoWPAN 248 standards [RFC6775], and [RFC6282] provide useful functionality for 249 reducing overhead, which are applied to Bluetooth LE. This 250 functionality comprises of link-local IPv6 addresses and stateless 251 IPv6 address autoconfiguration (see Section 3.2.1), Neighbor 252 Discovery (see Section 3.2.2) and header compression (see 253 Section 3.2.3). Fragmentation features from 6LoWPAN standards are 254 not used due Bluetooth LE's link layer fragmentation support (see 255 Section 2.4). 257 A significant difference between IEEE 802.15.4 and Bluetooth LE is 258 that the former supports both star and mesh topology (and requires a 259 routing protocol), whereas Bluetooth LE does not currently support 260 the formation of multihop networks at the link layer. 262 In Bluetooth LE a central node is assumed to be less constrained than 263 a peripheral node. Hence, in the primary deployment scenario central 264 and peripheral will act as 6LoWPAN Border Router (6LBR) and a 6LoWPAN 265 Node (6LN), respectively. 267 Before any IP-layer communications can take place over Bluetooth LE, 268 Bluetooth LE enabled nodes such as 6LNs and 6LBRs have to find each 269 other and establish a suitable link-layer connection. The discovery 270 and Bluetooth LE connection setup procedures are documented by 271 Bluetooth SIG in the IPSP specification [IPSP]. 273 In the rare case of Bluetooth LE random device address conflict, a 274 6LBR can detect multiple 6LNs with the same Bluetooth LE device 275 address, as well as a 6LN with the same Bluetooth LE address as the 276 6LBR. The 6LBR MUST ignore 6LNs with the same device address the 277 6LBR has, and the 6LBR MUST have at most one connection for a given 278 Bluetooth LE device address at any given moment. This will avoid 279 addressing conflicts within a Bluetooth LE network. The IPSP depends 280 on Bluetooth version 4.1, and hence both Bluetooth version 4.1, or 281 newer, and IPSP version 1.0, or newer, are required for IPv6 282 communications. 284 3.1. Protocol stack 286 Figure 3 illustrates IPv6 over Bluetooth LE stack including the 287 Internet Protocol Support Service. UDP and TCP are provided as 288 examples of transport protocols, but the stack can be used by any 289 other upper layer protocol capable of running atop of IPv6. The 290 6LoWPAN layer runs on top of Bluetooth LE L2CAP layer. 292 +---------+ +----------------------------+ 293 | IPSS | | UDP/TCP/other | 294 +---------+ +----------------------------+ 295 | GATT | | IPv6 | 296 +---------+ +----------------------------+ 297 | ATT | | 6LoWPAN for Bluetooth LE | 298 +---------+--+----------------------------+ 299 | Bluetooth LE L2CAP | 300 - - +-----------------------------------------+- - - HCI 301 | Bluetooth LE Link Layer | 302 +-----------------------------------------+ 303 | Bluetooth LE Physical | 304 +-----------------------------------------+ 306 Figure 3: IPv6 over Bluetooth LE Stack 308 3.2. Link model 310 The concept of IPv6 link (layer 3) and the physical link (combination 311 of PHY and MAC) needs to be clear and the relationship has to be well 312 understood in order to specify the addressing scheme for transmitting 313 IPv6 packets over the Bluetooth LE link. RFC 4861 [RFC4861] defines 314 a link as "a communication facility or medium over which nodes can 315 communicate at the link layer, i.e., the layer immediately below 316 IPv6." 318 In the case of Bluetooth LE, 6LoWPAN layer is adapted to support 319 transmission of IPv6 packets over Bluetooth LE. The IPSP defines all 320 steps required for setting up the Bluetooth LE connection over which 321 6LoWPAN can function [IPSP], including handling the link-layer 322 fragmentation required on Bluetooth LE, as described in Section 2.4. 323 Even though MTUs larger than 1280 bytes can be supported, use of 1280 324 byte is RECOMMENDED in order to avoid need for Path MTU discovery 325 procedures. 327 While Bluetooth LE protocols, such as L2CAP, utilize little-endian 328 byte orderering, IPv6 packets MUST be transmitted in big endian order 329 (network byte order). 331 This specification requires IPv6 header compression format specified 332 in RFC 6282 to be used [RFC6282]. It is assumed that the IPv6 333 payload length can be inferred from the L2CAP header length and the 334 possibly elided IPv6 address can be inferred from the link-layer 335 address, at the time of Bluetooth LE connection establishment, from 336 the HCI Connection Handle during connection, and from context if any. 338 Bluetooth LE connections used to build a star topology are point-to- 339 point in nature, as Bluetooth broadcast features are not used for 340 IPv6 over Bluetooth LE. For Bluetooth LE multilink model has been 341 chosen. Because of this, link-local multicast communications can 342 happen only within a single Bluetooth LE connection, and thus 6LN-to- 343 6LN communications using link-local addresses are not possible. 6LNs 344 connected to the same 6LBR has to communicate with each other by 345 using the shared prefix used on the subnet. The 6LBR ensures address 346 collisions do not occur (see Section 3.2.2). 348 After the peripheral and central have connected at the Bluetooth LE 349 level, the link can be considered up and IPv6 address configuration 350 and transmission can begin. 352 3.2.1. Stateless address autoconfiguration 354 At network interface initialization, both 6LN and 6LBR SHALL generate 355 and assign to the Bluetooth LE network interface IPv6 link-local 356 addresses [RFC4862] based on the 48-bit Bluetooth device addresses 357 (see Section 2.3) that were used for establishing underlying 358 Bluetooth LE connection. Following guidance of [RFC7136], a 64-bit 359 Interface Identifier (IID) is formed from 48-bit Bluetooth device 360 address by inserting two octets, with hexadecimal values of 0xFF and 361 0xFE in the middle of the 48-bit Bluetooth device address as shown in 362 Figure 4. In the Figure letter 'b' represents a bit from Bluetooth 363 device address, copied as is without any changes on any bit. This 364 means that no bit in IID indicates whether the underlying Bluetooth 365 device address is public or random. 367 |0 1|1 3|3 4|4 6| 368 |0 5|6 1|2 7|8 3| 369 +----------------+----------------+----------------+----------------+ 370 |bbbbbbbbbbbbbbbb|bbbbbbbb11111111|11111110bbbbbbbb|bbbbbbbbbbbbbbbb| 371 +----------------+----------------+----------------+----------------+ 373 Figure 4: Formation of IID from Bluetooth device adddress 375 The IID is then appended with prefix fe80::/64, as described in RFC 376 4291 [RFC4291] and as depicted in Figure 5. The same link-local 377 address SHALL be used for the lifetime of the Bluetooth LE L2CAP 378 channel. (After Bluetooth LE logical link has been established, it 379 is referenced with a Connection Handle in HCI. Thus possibly 380 changing device addresses do not impact data flows within existing 381 L2CAP channel. Hence there is no need to change IPv6 link-local 382 addresses even if devices change their random device addresses during 383 L2CAP channel lifetime). 385 10 bits 54 bits 64 bits 386 +----------+-----------------+----------------------+ 387 |1111111010| zeros | Interface Identifier | 388 +----------+-----------------+----------------------+ 390 Figure 5: IPv6 link-local address in Bluetooth LE 392 A 6LN MUST join the all-nodes multicast address. There is no need 393 for 6LN to join the solicited-node multicast address, since 6LBR will 394 know device addresses and hence link-local addresses of all connected 395 6LNs. The 6LBR will ensure no two devices with the same Bluetooth LE 396 device address are connected at the same time. Effectively duplicate 397 address detection for link-local addresses is performed by the 6LBR's 398 software responsible of discovery of IP-enabled Bluetooth LE nodes 399 and of starting Bluetooth LE connection establishment procedures. 400 This approach increases complexity of 6LBR, but reduces power 401 consumption on both 6LN and 6LBR at link establishment phase by 402 reducing number of mandatory packet transmissions. 404 After link-local address configuration, 6LN sends Router Solicitation 405 messages as described in [RFC4861] Section 6.3.7. 407 For non-link-local addresses a 64-bit IID MAY be formed by utilizing 408 the 48-bit Bluetooth device address. A 6LN can also use a randomly 409 generated IID (see Section 3.2.2), for example, as discussed in 410 [I-D.ietf-6man-default-iids], or use alternatice schemes such as 411 Cryptographically Generated Addresses (CGA) [RFC3972], privacy 412 extensions [RFC4941], Hash-Based Addresses (HBA, [RFC5535]), or 413 DHCPv6 [RFC3315]. The non-link-local addresses 6LN generates MUST be 414 registered with 6LBR as described in Section 3.2.2. 416 The tool for a 6LBR to obtain an IPv6 prefix for numbering the 417 Bluetooth LE network is out of scope of this document, but can be, 418 for example, accomplished via DHCPv6 Prefix Delegation [RFC3633] or 419 by using Unique Local IPv6 Unicast Addresses (ULA) [RFC4193]. Due to 420 the link model of the Bluetooth LE (see Section 2.2) the 6LBR MUST 421 set the "on-link" flag (L) to zero in the Prefix Information Option 422 [RFC4861]. This will cause 6LNs to always send packets to the 6LBR, 423 including the case when the destination is another 6LN using the same 424 prefix. 426 3.2.2. Neighbor discovery 428 'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless 429 Personal Area Networks (6LoWPANs)' [RFC6775] describes the neighbor 430 discovery approach as adapted for use in several 6LoWPAN topologies, 431 including the mesh topology. Bluetooth LE does not support mesh 432 networks and hence only those aspects that apply to a star topology 433 are considered. 435 The following aspects of the Neighbor Discovery optimizations 436 [RFC6775] are applicable to Bluetooth LE 6LNs: 438 1. A Bluetooth LE 6LN MUST NOT register its link-local address. A 439 Bluetooth LE 6LN MUST register its non-link-local addresses with the 440 6LBR by sending a Neighbor Solicitation (NS) message with the Address 441 Registration Option (ARO) and process the Neighbor Advertisement (NA) 442 accordingly. The NS with the ARO option MUST be sent irrespective of 443 the method used to generate the IID. If the 6LN registers for a same 444 compression context multiple addresses that are not based on 445 Bluetooth device address, the 6LN and 6LBR will be unable to compress 446 IIDs and hence have to send IID bits inline. 448 2. For sending Router Solicitations and processing Router 449 Advertisements the Bluetooth LE 6LNs MUST, respectively, follow 450 Sections 5.3 and 5.4 of the [RFC6775]. 452 3.2.3. Header compression 454 Header compression as defined in RFC 6282 [RFC6282], which specifies 455 the compression format for IPv6 datagrams on top of IEEE 802.15.4, is 456 REQUIRED in this document as the basis for IPv6 header compression on 457 top of Bluetooth LE. All headers MUST be compressed according to RFC 458 6282 [RFC6282] encoding formats. 460 The Bluetooth LE's star topology structure and ARO can be exploited 461 in order to provide a mechanism for address compression. The 462 following text describes the principles of IPv6 address compression 463 on top of Bluetooth LE. 465 The ARO option requires use of EUI-64 identifier [RFC6775]. In the 466 case of Bluetooth LE, the field SHALL be filled with the 48-bit 467 device address used by the Bluetooth LE node converted into 64-bit 468 Modified EUI-64 format [RFC4291]. 470 To enable efficient header compression, the 6LBR MUST include 6LoWPAN 471 Context Option (6CO) [RFC6775] for all prefixes the 6LBR advertises 472 in Router Advertisements for use in stateless address 473 autoconfiguration. 475 When a 6LN is sending a packet to or through a 6LBR, it MUST fully 476 elide the source address if it is a link-local address or a non-link- 477 local address 6LN has registered with ARO to the 6LBR for the 478 indicated prefix. That is, if SAC=0 and SAM=11 the 6LN MUST be using 479 the link-local IPv6 address derived from Bluetooth LE device address, 480 and if SAC=1 and SAM=11 the 6LN MUST have registered the source IPv6 481 address with the prefix related to compression context identified 482 with Context Identifier Extension. The destination IPv6 address MUST 483 be fully elided if the destination address is the same address to 484 which the 6LN has succesfully registered its source IPv6 address with 485 ARO (set DAC=0, DAM=11). The destination IPv6 address MUST be fully 486 or partially elided if context has been set up for the destination 487 address. For example, DAC=0 and DAM=01 when destination prefix is 488 link-local, and DAC=1 and DAM=01 with Context Identifier Extension if 489 compression context has been configured for the used destination 490 prefix. 492 When a 6LBR is transmitting packets to 6LN, it MUST fully elide the 493 source IID if the source IPv6 address is the one 6LN has used to 494 register its address with ARO (set SAC=0, SAM=11), and it MUST elide 495 the source prefix or address if a compression context related to the 496 IPv6 source address has been set up. The 6LBR also MUST elide the 497 destination IPv6 address registered by the 6LN with ARO and thus 6LN 498 can determine it based on indication of link-local prefix (DAC=0) or 499 indication of other prefix (DAC=1 with Context Identifier Extension). 501 3.2.3.1. Remote destination example 503 When a 6LN transmits an IPv6 packet to a remote destination using 504 global Unicast IPv6 addresses, if a context is defined for the 6LN's 505 global IPv6 address, the 6LN has to indicate this context in the 506 corresponding source fields of the compressed IPv6 header as per 507 Section 3.1 of RFC 6282 [RFC6282], and has to elide the full IPv6 508 source address previously registered with ARO. For this, the 6LN 509 MUST use the following settings in the IPv6 compressed header: CID=1, 510 SAC=1, SAM=11. In this case, the 6LBR can infer the elided IPv6 511 source address since 1) the 6LBR has previously assigned the prefix 512 to the 6LNs; and 2) the 6LBR maintains a Neighbor Cache that relates 513 the Device Address and the IID the device has registered with ARO. 514 If a context is defined for the IPv6 destination address, the 6LN has 515 to also indicate this context in the corresponding destination fields 516 of the compressed IPv6 header, and elide the prefix of or the full 517 destination IPv6 address. For this, the 6LN MUST set the DAM field 518 of the compressed IPv6 header as DAM=01 (if the context covers a 519 64-bit prefix) or as DAM=11 (if the context covers a full, 128-bit 520 address). CID and DAC MUST be set to CID=1 and DAC=1. Note that 521 when a context is defined for the IPv6 destination address, the 6LBR 522 can infer the elided destination prefix by using the context. 524 When a 6LBR receives an IPv6 packet sent by a remote node outside the 525 Bluetooth LE network, and the destination of the packet is a 6LN, if 526 a context is defined for the prefix of the 6LN's global IPv6 address, 527 the 6LBR has to indicate this context in the corresponding 528 destination fields of the compressed IPv6 header. The 6LBR has to 529 elide the IPv6 destination address of the packet before forwarding 530 it, if the IPv6 destination address is inferable by the 6LN. For 531 this, the 6LBR will set the DAM field of the IPv6 compressed header 532 as DAM=11. CID and DAC needs to be set to CID=1 and DAC=1. If a 533 context is defined for the IPv6 source address, the 6LBR needs to 534 indicate this context in the source fields of the compressed IPv6 535 header, and elide that prefix as well. For this, the 6LBR needs to 536 set the SAM field of the IPv6 compressed header as SAM=01 (if the 537 context covers a 64-bit prefix) or SAM=11 (if the context covers a 538 full, 128-bit address). CID and SAC are to be set to CID=1 and 539 SAC=1. 541 3.2.4. Unicast and Multicast address mapping 543 The Bluetooth LE link layer does not support multicast. Hence 544 traffic is always unicast between two Bluetooth LE nodes. Even in 545 the case where a 6LBR is attached to multiple 6LNs, the 6LBR cannot 546 do a multicast to all the connected 6LNs. If the 6LBR needs to send 547 a multicast packet to all its 6LNs, it has to replicate the packet 548 and unicast it on each link. However, this may not be energy- 549 efficient and particular care must be taken if the master is battery- 550 powered. In the opposite direction, a 6LN always has to send packets 551 to or through 6LBR. Hence, when a 6LN needs to transmit an IPv6 552 multicast packet, the 6LN will unicast the corresponding Bluetooth LE 553 packet to the 6LBR. 555 3.3. Subnets and Internet connectivity scenarios 557 In a typical scenario, the Bluetooth LE network is connected to the 558 Internet as shown in the Figure 6. In this scenario, the Bluetooth 559 LE star is deployed as one subnet, using one /64 IPv6 prefix, with 560 each spoke representing individual link. The 6LBR is acting as 561 router and forwarding packets between 6LNs and to and from Internet. 563 / 564 .---------------. / 565 / 6LN \ / 566 / \ \ / 567 | \ | / 568 | 6LN ----------- 6LBR ----- | Internet 569 | <--Link--> / | \ 570 \ / / \ 571 \ 6LN / \ 572 '---------------' \ 573 \ 575 <------ Subnet -----><-- IPv6 connection --> 576 to Internet 578 Figure 6: Bluetooth LE network connected to the Internet 580 In some scenarios, the Bluetooth LE network may transiently or 581 permanently be an isolated network as shown in the Figure 7. In this 582 case the whole star consist of a single subnet with multiple links, 583 where 6LBR is at central routing packets between 6LNs. 585 .-------------------. 586 / \ 587 / 6LN 6LN \ 588 / \ / \ 589 | \ / | 590 | 6LN --- 6LBR --- 6LN | 591 | / \ | 592 \ / \ / 593 \ 6LN 6LN / 594 \ / 595 '-------------------' 596 <--------- Subnet ----------> 598 Figure 7: Isolated Bluetooth LE network 600 It is also possible to have point-to-point connection between two 601 6LNs, one of which being central and another being peripheral. 602 Similarly, it is possible to have point-to-point connections between 603 two 6LBRs, one of which being central and another being peripheral. 605 At this point in time mesh networking with Bluetooth LE is not 606 specified. 608 4. IANA Considerations 610 There are no IANA considerations related to this document. 612 5. Security Considerations 614 The transmission of IPv6 over Bluetooth LE links has similar 615 requirements and concerns for security as for IEEE 802.15.4. 616 Bluetooth LE Link Layer security considerations are covered by the 617 IPSP [IPSP]. 619 Bluetooth LE Link Layer supports encryption and authentication by 620 using the Counter with CBC-MAC (CCM) mechanism [RFC3610] and a 621 128-bit AES block cipher. Upper layer security mechanisms may 622 exploit this functionality when it is available. (Note: CCM does not 623 consume bytes from the maximum per-packet L2CAP data size, since the 624 link layer data unit has a specific field for them when they are 625 used.) 627 Key management in Bluetooth LE is provided by the Security Manager 628 Protocol (SMP), as defined in [BTCorev4.1]. 630 The IPv6 link-local address configuration described in Section 3.2.1 631 strictly binds the privacy level of IPv6 link-local address to the 632 privacy level device has selected for the Bluetooth LE. This means 633 that a device using Bluetooth privacy features will retain the same 634 level of privacy with generated IPv6 link-local addresses. 635 Respectively, device not using privacy at Bluetooth level will not 636 have privacy at IPv6 link-local address either. For non-link local 637 addresses implementations have a choice to support, for example, 638 [I-D.ietf-6man-default-iids], [RFC3972], [RFC4941] or [RFC5535]. 640 6. Additional contributors 642 Kanji Kerai, Jari Mutikainen, David Canfeng-Chen and Minjun Xi from 643 Nokia have contributed significantly to this document. 645 7. Acknowledgements 647 The Bluetooth, Bluetooth Smart and Bluetooth Smart Ready marks are 648 registred trademarks owned by Bluetooth SIG, Inc. 650 Samita Chakrabarti, Brian Haberman, Marcel De Kogel, Jouni Korhonen, 651 Erik Nordmark, Dave Thaler, Pascal Thubert, and Victor Zhodzishsky 652 have provided valuable feedback for this draft. 654 Authors would like to give special acknowledgements for Krishna 655 Shingala, Frank Berntsen, and Bluetooth SIG's Internet Working Group 656 for providing significant feedback and improvement proposals for this 657 document. 659 8. References 661 8.1. Normative References 663 [BTCorev4.1] 664 Bluetooth Special Interest Group, "Bluetooth Core 665 Specification Version 4.1", December 2013. 667 [IPSP] Bluetooth Special Interest Group, "Bluetooth Internet 668 Protocol Support Profile Specification Version 1.0.0", 669 December 2014. 671 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 672 Requirement Levels", BCP 14, RFC 2119, March 1997. 674 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 675 Architecture", RFC 4291, February 2006. 677 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 678 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 679 September 2007. 681 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 682 Address Autoconfiguration", RFC 4862, September 2007. 684 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 685 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 686 September 2011. 688 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 689 "Neighbor Discovery Optimization for IPv6 over Low-Power 690 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 691 November 2012. 693 [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 694 Interface Identifiers", RFC 7136, February 2014. 696 8.2. Informative References 698 [I-D.ietf-6man-default-iids] 699 Gont, F., Cooper, A., Thaler, D., and W. Will, 700 "Recommendation on Stable IPv6 Interface Identifiers", 701 draft-ietf-6man-default-iids-02 (work in progress), 702 January 2015. 704 [IEEE802-2001] 705 Institute of Electrical and Electronics Engineers (IEEE), 706 "IEEE 802-2001 Standard for Local and Metropolitan Area 707 Networks: Overview and Architecture", 2002. 709 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 710 and M. Carney, "Dynamic Host Configuration Protocol for 711 IPv6 (DHCPv6)", RFC 3315, July 2003. 713 [RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with 714 CBC-MAC (CCM)", RFC 3610, September 2003. 716 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 717 Host Configuration Protocol (DHCP) version 6", RFC 3633, 718 December 2003. 720 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 721 RFC 3972, March 2005. 723 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 724 Addresses", RFC 4193, October 2005. 726 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 727 Extensions for Stateless Address Autoconfiguration in 728 IPv6", RFC 4941, September 2007. 730 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 731 "Transmission of IPv6 Packets over IEEE 802.15.4 732 Networks", RFC 4944, September 2007. 734 [RFC5535] Bagnulo, M., "Hash-Based Addresses (HBA)", RFC 5535, June 735 2009. 737 Authors' Addresses 739 Johanna Nieminen 740 Nokia 742 Email: johannamaria.nieminen@gmail.com 744 Teemu Savolainen 745 Nokia 746 Visiokatu 3 747 Tampere 33720 748 Finland 750 Email: teemu.savolainen@nokia.com 752 Markus Isomaki 753 Nokia 754 Otaniementie 19 755 Espoo 02150 756 Finland 758 Email: markus.isomaki@nokia.com 760 Basavaraj Patil 761 AT&T 762 1410 E. Renner Road 763 Richardson, TX 75082 764 USA 766 Email: basavaraj.patil@att.com 768 Zach Shelby 769 Arm 770 Hallituskatu 13-17D 771 Oulu 90100 772 Finland 774 Email: zach.shelby@arm.com 775 Carles Gomez 776 Universitat Politecnica de Catalunya/i2CAT 777 C/Esteve Terradas, 7 778 Castelldefels 08860 779 Spain 781 Email: carlesgo@entel.upc.edu