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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 'IPSP' ** Downref: Normative reference to an Informational RFC: RFC 4541 == Outdated reference: A later version (-16) exists of draft-ietf-6man-default-iids-01 -- Obsolete informational reference (is this intentional?): RFC 3633 (Obsoleted by RFC 8415) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 3 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: June 19, 2015 Nokia 6 B. Patil 7 AT&T 8 Z. Shelby 9 Arm 10 C. Gomez 11 Universitat Politecnica de Catalunya/i2CAT 12 December 16, 2014 14 Transmission of IPv6 Packets over BLUETOOTH(R) Low Energy 15 draft-ietf-6lo-btle-04 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 June 19, 2015. 48 Copyright Notice 50 Copyright (c) 2014 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 . . . . . . . . . . . 6 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 . . . . . . . . . . . . . . . . . 9 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. Internet connectivity scenarios . . . . . . . . . . . . . 12 81 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 82 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 83 6. Additional contributors . . . . . . . . . . . . . . . . . . . 14 84 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 85 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 86 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 87 8.2. Informative References . . . . . . . . . . . . . . . . . 15 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 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 an especially attractive technology for Internet of Things 96 applications, such as health monitors, environmental sensing, 97 proximity applications and many others. 99 Considering the potential for the exponential growth in the number of 100 sensors and Internet connected devices and things, IPv6 is an ideal 101 protocol due to the large address space it provides. In addition, 102 IPv6 provides tools for stateless address autoconfiguration, which is 103 particularly suitable for sensor network applications and nodes which 104 have very limited processing power or lack a full-fledged operating 105 system. 107 RFC 4944 [RFC4944] specifies the transmission of IPv6 over IEEE 108 802.15.4. The Bluetooth LE link in many respects has similar 109 characteristics to that of IEEE 802.15.4. Many of the mechanisms 110 defined in the RFC 4944 can be applied to the transmission of IPv6 on 111 Bluetooth LE links. This document specifies the details of IPv6 112 transmission over Bluetooth LE links. 114 1.1. Terminology and Requirements Language 116 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 117 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 118 document are to be interpreted as described in RFC 2119 [RFC2119]. 120 The terms 6LN, 6LR and 6LBR are defined as in [RFC6775], with an 121 addition that Bluetooth LE central and Bluetooth LE peripheral (see 122 Section 2.2) can both be either 6LN or 6LBR. 124 2. Bluetooth Low Energy 126 Bluetooth LE is designed for transferring small amounts of data 127 infrequently at modest data rates at a very low cost per bit. 128 Bluetooth Special Interest Group (Bluetooth SIG) has introduced two 129 trademarks, Bluetooth Smart for single-mode devices (a device that 130 only supports Bluetooth LE) and Bluetooth Smart Ready for dual-mode 131 devices (devices that support both Bluetooth and Bluetooth LE). In 132 the rest of the document, the term Bluetooth LE refers to both types 133 of devices. 135 Bluetooth LE was introduced in Bluetooth 4.0 and further enhanced in 136 Bluetooth 4.1 [BTCorev4.1]. Bluetooth SIG has also published 137 Internet Protocol Support Profile (IPSP) [IPSP], which includes 138 Internet Protocol Support Service (IPSS). The IPSP enables discovery 139 of IP-enabled devices and establishment of link-layer connection for 140 transporting IPv6 packets. IPv6 over Bluetooth LE is dependent on 141 both Bluetooth 4.1 and IPSP 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 Node --. .-- Node 203 \ / 204 Node ---- Router ---- Node 205 / \ 206 Node --' '-- Node 208 Figure 2: Bluetooth LE Star Topology 210 In Bluetooth LE a central is assumed to be less constrained than a 211 peripheral. Hence, in the primary deployment scenario central and 212 peripheral will act as 6LoWPAN Border Router (6LBR) and a 6LoWPAN 213 Node (6LN), respectively. 215 In Bluetooth LE, direct communication only takes place between a 216 central and a peripheral. Hence, in a Bluetooth LE network using 217 IPv6, a radio hop is equivalent to an IPv6 link and vice versa. 219 2.3. Bluetooth LE device addressing 221 Every Bluetooth LE device is identified by a 48-bit device address. 222 The Bluetooth specification describes the device address of a 223 Bluetooth LE device as:"Devices are identified using a device 224 address. Device addresses may be either a public device address or a 225 random device address." [BTCorev4.1]. The public device addresses 226 are based on the IEEE 802-2001 standard [IEEE802-2001]. The random 227 device addresses are generated as defined in the Bluetooth 228 specification. These random device addresses have a very small 229 chance of being in conflict, as Bluetooth LE does not support random 230 device address collision avoidance or detection. 232 2.4. Bluetooth LE packets sizes and MTU 234 Optimal MTU defined for L2CAP fixed channels over Bluetooth LE is 27 235 bytes including the L2CAP header of four bytes. Default MTU for 236 Bluetooth LE is hence defined to be 27 bytes. Therefore, excluding 237 L2CAP header of four bytes, protocol data unit (PDU) size of 23 bytes 238 is available for upper layers. In order to be able to transmit IPv6 239 packets of 1280 bytes or larger, link layer fragmentation and 240 reassembly solution is provided by the L2CAP layer. The IPSP defines 241 means for negotiating up a link-layer connection that provides MTU of 242 1280 bytes or higher for the IPv6 layer [IPSP]. The link-layer MTU 243 is negotiated separately for each direction. Implementations that 244 require single link-layer MTU value SHALL use the smallest of the 245 possibly different MTU values. 247 3. Specification of IPv6 over Bluetooth Low Energy 249 Before any IP-layer communications can take place over Bluetooth LE, 250 Bluetooth LE enabled nodes such as 6LNs and 6LBRs have to find each 251 other and establish a suitable link-layer connection. The discovery 252 and Bluetooth LE connection setup procedures are documented by 253 Bluetooth SIG in the IPSP specification [IPSP]. In the rare case of 254 Bluetooth LE random device address conflict, the 6LBR can detect 255 multiple 6LNs with the same Bluetooth LE device address. The 6LBR 256 MUST have at most one connection for a given Bluetooth LE device 257 address at any given moment. This will avoid addressing conflicts 258 within a Bluetooth LE network. The IPSP depends on Bluetooth version 259 4.1, and hence both Bluetooth version 4.1, or newer, and IPSP version 260 1.0, or newer, are required for IPv6 communications. 262 Bluetooth LE technology sets strict requirements for low power 263 consumption and thus limits the allowed protocol overhead. 6LoWPAN 264 standards [RFC6775], and [RFC6282] provide useful functionality for 265 reducing overhead which can be applied to Bluetooth LE. This 266 functionality comprises of link-local IPv6 addresses and stateless 267 IPv6 address autoconfiguration (see Section 3.2.1), Neighbor 268 Discovery (see Section 3.2.2) and header compression (see 269 Section 3.2.3). 271 A significant difference between IEEE 802.15.4 and Bluetooth LE is 272 that the former supports both star and mesh topology (and requires a 273 routing protocol), whereas Bluetooth LE does not currently support 274 the formation of multihop networks at the link layer. 276 3.1. Protocol stack 278 Figure 3 illustrates IPv6 over Bluetooth LE stack including the 279 Internet Protocol Support Service. UDP and TCP are provided as 280 examples of transport protocols, but the stack can be used by any 281 other upper layer protocol capable of running atop of IPv6. The 282 6LoWPAN layer runs on top of Bluetooth LE L2CAP layer. 284 +---------+ +----------------------------+ 285 | IPSS | | UDP/TCP/other | 286 +---------+ +----------------------------+ 287 | GATT | | IPv6 | 288 +---------+ +----------------------------+ 289 | ATT | | 6LoWPAN for Bluetooth LE | 290 +---------+--+----------------------------+ 291 | Bluetooth LE L2CAP | 292 - - +-----------------------------------------+- - - HCI 293 | Bluetooth LE Link Layer | 294 +-----------------------------------------+ 295 | Bluetooth LE Physical | 296 +-----------------------------------------+ 298 Figure 3: IPv6 over Bluetooth LE Stack 300 3.2. Link model 302 The concept of IPv6 link (layer 3) and the physical link (combination 303 of PHY and MAC) needs to be clear and the relationship has to be well 304 understood in order to specify the addressing scheme for transmitting 305 IPv6 packets over the Bluetooth LE link. RFC 4861 [RFC4861] defines 306 a link as "a communication facility or medium over which nodes can 307 communicate at the link layer, i.e., the layer immediately below 308 IPv6." 310 In the case of Bluetooth LE, 6LoWPAN layer is adapted to support 311 transmission of IPv6 packets over Bluetooth LE. The IPSP defines all 312 steps required for setting up the Bluetooth LE connection over which 313 6LoWPAN can function [IPSP], including handling the link-layer 314 fragmentation required on Bluetooth LE, as described in Section 2.4. 316 While Bluetooth LE protocols, such as L2CAP, utilize little-endian 317 byte orderering, IPv6 packets MUST be transmitted in big endian order 318 (network byte order). 320 This specification requires IPv6 header compression format specified 321 in RFC 6282 to be used [RFC6282]. It is assumed that the IPv6 322 payload length can be inferred from the L2CAP header length and the 323 IID value inferred from the link-layer address with help of Neighbor 324 Cache, if elided from compressed packet header. 326 Bluetooth LE connections used to build a star topology are point-to- 327 point in nature, as Bluetooth broadcast features are not used for 328 IPv6 over Bluetooth LE. 6LN-to-6LN communications, e.g. using link- 329 local addresses, need to be bridged by the 6LBR. The 6LBR ensures 330 address collisions do not occur (see Section 3.2.2). 332 After the peripheral and central have connected at the Bluetooth LE 333 level, the link can be considered up and IPv6 address configuration 334 and transmission can begin. 336 3.2.1. Stateless address autoconfiguration 338 At network interface initialization, both 6LN and 6LBR SHALL generate 339 and assign to the Bluetooth LE network interface IPv6 link-local 340 addresses [RFC4862] based on the 48-bit Bluetooth device addresses 341 (see Section 2.3) that were used for establishing underlying 342 Bluetooth LE connection. A 64-bit Interface Identifier (IID) is 343 formed from 48-bit device address as defined in RFC 2464 [RFC2464]. 344 The IID is then appended with prefix fe80::/64, as described in RFC 345 4291 [RFC4291] and as depicted in Figure 4. The same link-local 346 address SHALL be used for the lifetime of the Bluetooth LE L2CAP 347 channel. (After Bluetooth LE logical link has been established, it 348 is referenced with a Connection Handle in HCI. Thus possibly 349 changing device addresses do not impact data flows within existing 350 L2CAP channel. Hence there is no need to change IPv6 link-local 351 addresses even if devices change their random device addresses during 352 L2CAP channel lifetime). 354 10 bits 54 bits 64 bits 355 +----------+-----------------+----------------------+ 356 |1111111010| zeros | Interface Identifier | 357 +----------+-----------------+----------------------+ 359 Figure 4: IPv6 link-local address in Bluetooth LE 361 A 6LN MUST join the all-nodes multicast address. There is no need 362 for 6LN to join the solicited-node multicast address, since 6LBR will 363 know device addresses and hence link-local addresses of all connected 364 6LNs. The 6LBR will ensure no two devices with the same Bluetooth LE 365 device address are connected at the same time. Effectively duplicate 366 address detection for link-local addresses is performed by the 6LBR's 367 software responsible of discovery of IP-enabled Bluetooth LE nodes 368 and of starting Bluetooth LE connection establishment procedures. 370 This approach increases complexity of 6LBR, but reduces power 371 consumption on both 6LN and 6LBR at link establishment phase by 372 reducing number of mandatory packet transmissions. 374 After link-local address configuration, 6LN sends Router Solicitation 375 messages as described in [RFC4861] Section 6.3.7. 377 For non-link-local addresses a 64-bit IID MAY be formed by utilizing 378 the 48-bit Bluetooth device address. Alternatively, a randomly 379 generated IID (see Section 3.2.2) can be used instead, for example, 380 as discussed in [I-D.ietf-6man-default-iids]. The non-link-local 381 addresses 6LN generates must be registered with 6LBR as described in 382 Section 3.2.2. 384 Only if the Bluetooth device address is known to be a public address 385 the "Universal/Local" bit can be set to 1 [RFC4291]. 387 The tool for a 6LBR to obtain an IPv6 prefix for numbering the 388 Bluetooth LE network is out of scope of this document, but can be, 389 for example, accomplished via DHCPv6 Prefix Delegation [RFC3633] or 390 by using Unique Local IPv6 Unicast Addresses (ULA) [RFC4193]. Due to 391 the link model of the Bluetooth LE (see Section 2.2) the 6LBR MUST 392 set the "on-link" flag (L) to zero in the Prefix Information Option 393 [RFC4861]. This will cause 6LNs to always send packets to the 6LBR, 394 including the case when the destination is another 6LN using the same 395 prefix. 397 3.2.2. Neighbor discovery 399 'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless 400 Personal Area Networks (6LoWPANs)' [RFC6775] describes the neighbor 401 discovery approach as adapted for use in several 6LoWPAN topologies, 402 including the mesh topology. Bluetooth LE does not support mesh 403 networks and hence only those aspects that apply to a star topology 404 are considered. 406 The following aspects of the Neighbor Discovery optimizations 407 [RFC6775] are applicable to Bluetooth LE 6LNs: 409 1. A Bluetooth LE 6LN MUST register its non-link-local addresses 410 with the 6LBR by sending a Neighbor Solicitation (NS) message with 411 the Address Registration Option (ARO) and process the Neighbor 412 Advertisement (NA) accordingly. The NS with the ARO option MUST be 413 sent irrespective of the method used to generate the IID. The 6LN 414 MUST register only one IPv6 address per IPv6 prefix available on a 415 link. 417 2. For sending Router Solicitations and processing Router 418 Advertisements the Bluetooth LE 6LNs MUST, respectively, follow 419 Sections 5.3 and 5.4 of the [RFC6775]. 421 3.2.3. Header compression 423 Header compression as defined in RFC 6282 [RFC6282], which specifies 424 the compression format for IPv6 datagrams on top of IEEE 802.15.4, is 425 REQUIRED in this document as the basis for IPv6 header compression on 426 top of Bluetooth LE. All headers MUST be compressed according to RFC 427 6282 [RFC6282] encoding formats. 429 The Bluetooth LE's star topology structure and ARO can be exploited 430 in order to provide a mechanism for IID compression. The following 431 text describes the principles of IPv6 address compression on top of 432 Bluetooth LE. 434 The ARO option requires use of EUI-64 identifier [RFC6775]. In the 435 case of Bluetooth LE, the field SHALL be filled with the 48-bit 436 device address used by the Bluetooth LE node converted into 64-bit 437 Modified EUI-64 format [RFC4291]. 439 To enable efficient header compression, the 6LBR MUST include 6LoWPAN 440 Context Option (6CO) [RFC6775] for all prefixes the 6LBR advertises 441 in Router Advertisements for use in stateless address 442 autoconfiguration. 444 When a 6LN is sending a packet to or through a 6LBR, it MUST fully 445 elide the source address if it is a link-local address or a non-link- 446 local address 6LN has registered with ARO to the 6LBR for the 447 indicated prefix. That is, if SAC=0 and SAM=11 the 6LN MUST be using 448 the link-local IPv6 address derived from Bluetooth LE device address, 449 and if SAC=1 and SAM=11 the 6LN MUST have registered the source IPv6 450 address with the prefix related to compression context identified 451 with Context Identifier Extension. The destination IPv6 address MUST 452 be fully elided if the destination address is the same address to 453 which the 6LN has succesfully registered its source IPv6 address with 454 ARO (set DAC=0, DAM=11). The destination IPv6 address MUST be fully 455 or partially elided if context has been set up for the destination 456 address. For example, DAC=0 and DAM=01 when destination prefix is 457 link-local, and DAC=1 and DAM=01 with Context Identifier Extension if 458 compression context has been configured for the used destination 459 prefix. 461 When a 6LBR is transmitting packets to 6LN, it MUST fully elide the 462 source IID if the source IPv6 address is the one 6LN has used to 463 register its address with ARO (set SAC=0, SAM=11), and it MUST elide 464 the source prefix or address if a compression context related to the 465 IPv6 source address has been set up. The 6LBR also MUST elide the 466 destination IPv6 address registered by the 6LN with ARO and thus 6LN 467 can determine it based on indication of link-local prefix (DAC=0) or 468 indication of other prefix (DAC=1 with Context Identifier Extension). 470 3.2.3.1. Remote destination example 472 When a 6LN transmits an IPv6 packet to a remote destination using 473 global Unicast IPv6 addresses, if a context is defined for the 6LN's 474 global IPv6 address, the 6LN has to indicate this context in the 475 corresponding source fields of the compressed IPv6 header as per 476 Section 3.1 of RFC 6282 [RFC6282], and has to elide the full IPv6 477 source address previously registered with ARO. For this, the 6LN 478 MUST use the following settings in the IPv6 compressed header: CID=1, 479 SAC=1, SAM=11. In this case, the 6LBR can infer the elided IPv6 480 source address since 1) the 6LBR has previously assigned the prefix 481 to the 6LNs; and 2) the 6LBR maintains a Neighbor Cache that relates 482 the Device Address and the IID the device has registered with ARO. 483 If a context is defined for the IPv6 destination address, the 6LN has 484 to also indicate this context in the corresponding destination fields 485 of the compressed IPv6 header, and elide the prefix of or the full 486 destination IPv6 address. For this, the 6LN MUST set the DAM field 487 of the compressed IPv6 header as DAM=01 (if the context covers a 488 64-bit prefix) or as DAM=11 (if the context covers a full, 128-bit 489 address). CID and DAC MUST be set to CID=1 and DAC=1. Note that 490 when a context is defined for the IPv6 destination address, the 6LBR 491 can infer the elided destination prefix by using the context. 493 When a 6LBR receives an IPv6 packet sent by a remote node outside the 494 Bluetooth LE network, and the destination of the packet is a 6LN, if 495 a context is defined for the prefix of the 6LN's global IPv6 address, 496 the 6LBR has to indicate this context in the corresponding 497 destination fields of the compressed IPv6 header. The 6LBR has to 498 elide the IPv6 destination address of the packet before forwarding 499 it, if the IPv6 destination address is inferable by the 6LN. For 500 this, the 6LBR will set the DAM field of the IPv6 compressed header 501 as DAM=11. CID and DAC needs to be set to CID=1 and DAC=1. If a 502 context is defined for the IPv6 source address, the 6LBR needs to 503 indicate this context in the source fields of the compressed IPv6 504 header, and elide that prefix as well. For this, the 6LBR needs to 505 set the SAM field of the IPv6 compressed header as SAM=01 (if the 506 context covers a 64-bit prefix) or SAM=11 (if the context covers a 507 full, 128-bit address). CID and SAC are to be set to CID=1 and 508 SAC=1. 510 3.2.4. Unicast and Multicast address mapping 512 The Bluetooth LE link layer does not support multicast. Hence 513 traffic is always unicast between two Bluetooth LE nodes. Even in 514 the case where a 6LBR is attached to multiple 6LNs, the 6LBR cannot 515 do a multicast to all the connected 6LNs. If the 6LBR needs to send 516 a multicast packet to all its 6LNs, it has to replicate the packet 517 and unicast it on each link. However, this may not be energy- 518 efficient and particular care must be taken if the master is battery- 519 powered. In the opposite direction, a 6LN always has to send packets 520 to or through 6LBR. Hence, when a 6LN needs to transmit an IPv6 521 multicast packet, the 6LN will unicast the corresponding Bluetooth LE 522 packet to the 6LBR. The 6LBR will then forward the multicast packet 523 to other 6LNs. To avoid excess of unwanted multicast traffic being 524 sent to 6LNs, the 6LBR SHOULD implement MLD Snooping feature 525 [RFC4541]. 527 3.3. Internet connectivity scenarios 529 In a typical scenario, the Bluetooth LE network is connected to the 530 Internet as shown in the Figure 5. 532 6LN 533 \ ____________ 534 \ / \ 535 6LN ---- 6LBR ----- | Internet | 536 / \____________/ 537 / 538 6LN 540 <-- Bluetooth LE --> 542 Figure 5: Bluetooth LE network connected to the Internet 544 In some scenarios, the Bluetooth LE network may transiently or 545 permanently be an isolated network as shown in the Figure 6. 547 6LN 6LN 548 \ / 549 \ / 550 6LN --- 6LBR --- 6LN 551 / \ 552 / \ 553 6LN 6LN 555 <--- Bluetooth LE ---> 557 Figure 6: Isolated Bluetooth LE network 559 It is also possible to have point-to-point connection between two 560 6LNs, one of which being central and another being peripheral. 561 Similarly, it is possible to have point-to-point connections between 562 two 6LBRs, one of which being central and another being peripheral. 564 At this point in time mesh networking with Bluetooth LE is not 565 specified. 567 4. IANA Considerations 569 There are no IANA considerations related to this document. 571 5. Security Considerations 573 The transmission of IPv6 over Bluetooth LE links has similar 574 requirements and concerns for security as for IEEE 802.15.4. 575 Bluetooth LE Link Layer security considerations are covered by the 576 IPSP [IPSP]. 578 Bluetooth LE Link Layer supports encryption and authentication by 579 using the Counter with CBC-MAC (CCM) mechanism [RFC3610] and a 580 128-bit AES block cipher. Upper layer security mechanisms may 581 exploit this functionality when it is available. (Note: CCM does not 582 consume bytes from the maximum per-packet L2CAP data size, since the 583 link layer data unit has a specific field for them when they are 584 used.) 586 Key management in Bluetooth LE is provided by the Security Manager 587 Protocol (SMP), as defined in [BTCorev4.1]. 589 The IPv6 link-local address configuration described in Section 3.2.1 590 strictly binds the privacy level of IPv6 link-local address to the 591 privacy level device has selected for the Bluetooth LE. This means 592 that a device using Bluetooth privacy features will retain the same 593 level of privacy with generated IPv6 link-local addresses. 594 Respectively, device not using privacy at Bluetooth level will not 595 have privacy at IPv6 link-local address either. For non-link local 596 addresses implementations have a choice to support 597 [I-D.ietf-6man-default-iids]. 599 6. Additional contributors 601 Kanji Kerai, Jari Mutikainen, David Canfeng-Chen and Minjun Xi from 602 Nokia have contributed significantly to this document. 604 7. Acknowledgements 606 The Bluetooth, Bluetooth Smart and Bluetooth Smart Ready marks are 607 registred trademarks owned by Bluetooth SIG, Inc. 609 Samita Chakrabarti, Erik Nordmark, Marcel De Kogel, Dave Thaler, and 610 Brian Haberman have provided valuable feedback for this draft. 612 Authors would like to give special acknowledgements for Krishna 613 Shingala, Frank Berntsen, and Bluetooth SIG's Internet Working Group 614 for providing significant feedback and improvement proposals for this 615 document. 617 8. References 619 8.1. Normative References 621 [BTCorev4.1] 622 Bluetooth Special Interest Group, "Bluetooth Core 623 Specification Version 4.1", December 2013. 625 [IPSP] Bluetooth Special Interest Group, "Bluetooth Internet 626 Protocol Support Profile Specification Version 1.0.0", 627 December 2014. 629 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 630 Requirement Levels", BCP 14, RFC 2119, March 1997. 632 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 633 Networks", RFC 2464, December 1998. 635 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 636 Architecture", RFC 4291, February 2006. 638 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 639 "Considerations for Internet Group Management Protocol 640 (IGMP) and Multicast Listener Discovery (MLD) Snooping 641 Switches", RFC 4541, May 2006. 643 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 644 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 645 September 2007. 647 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 648 Address Autoconfiguration", RFC 4862, September 2007. 650 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 651 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 652 September 2011. 654 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 655 "Neighbor Discovery Optimization for IPv6 over Low-Power 656 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 657 November 2012. 659 8.2. Informative References 661 [I-D.ietf-6man-default-iids] 662 Gont, F., Cooper, A., Thaler, D., and W. Will, 663 "Recommendation on Stable IPv6 Interface Identifiers", 664 draft-ietf-6man-default-iids-01 (work in progress), 665 October 2014. 667 [IEEE802-2001] 668 Institute of Electrical and Electronics Engineers (IEEE), 669 "IEEE 802-2001 Standard for Local and Metropolitan Area 670 Networks: Overview and Architecture", 2002. 672 [RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with 673 CBC-MAC (CCM)", RFC 3610, September 2003. 675 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 676 Host Configuration Protocol (DHCP) version 6", RFC 3633, 677 December 2003. 679 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 680 Addresses", RFC 4193, October 2005. 682 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 683 "Transmission of IPv6 Packets over IEEE 802.15.4 684 Networks", RFC 4944, September 2007. 686 Authors' Addresses 687 Johanna Nieminen 688 Nokia 690 Email: johannamaria.nieminen@gmail.com 692 Teemu Savolainen 693 Nokia 694 Visiokatu 3 695 Tampere 33720 696 Finland 698 Email: teemu.savolainen@nokia.com 700 Markus Isomaki 701 Nokia 702 Otaniementie 19 703 Espoo 02150 704 Finland 706 Email: markus.isomaki@nokia.com 708 Basavaraj Patil 709 AT&T 710 1410 E. Renner Road 711 Richardson, TX 75082 712 USA 714 Email: basavaraj.patil@att.com 716 Zach Shelby 717 Arm 718 Hallituskatu 13-17D 719 Oulu 90100 720 Finland 722 Email: zach.shelby@arm.com 723 Carles Gomez 724 Universitat Politecnica de Catalunya/i2CAT 725 C/Esteve Terradas, 7 726 Castelldefels 08860 727 Spain 729 Email: carlesgo@entel.upc.edu