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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. 'G.9959' ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 over Networks of Resource-constrained Nodes (6lo) WG A. Brandt 3 Internet-Draft J. Buron 4 Intended status: Standards Track Sigma Designs 5 Expires: March 22, 2015 September 18, 2014 7 Transmission of IPv6 packets over ITU-T G.9959 Networks 8 draft-ietf-6lo-lowpanz-06 10 Abstract 12 This document describes the frame format for transmission of IPv6 13 packets and a method of forming IPv6 link-local addresses and 14 statelessly autoconfigured IPv6 addresses on ITU-T G.9959 networks. 16 Requirements Language 18 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 19 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 20 document are to be interpreted as described in [RFC2119]. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on March 22, 2015. 39 Copyright Notice 41 Copyright (c) 2014 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Terms used . . . . . . . . . . . . . . . . . . . . . . . 3 58 2. G.9959 parameters to use for IPv6 transport . . . . . . . . . 5 59 2.1. Addressing mode . . . . . . . . . . . . . . . . . . . . . 5 60 2.2. IPv6 Multicast support . . . . . . . . . . . . . . . . . 6 61 2.3. G.9959 MAC PDU size and IPv6 MTU . . . . . . . . . . . . 6 62 2.4. Transmission status indications . . . . . . . . . . . . . 6 63 2.5. Transmission security . . . . . . . . . . . . . . . . . . 7 64 3. 6LoWPAN Adaptation Layer and Frame Format . . . . . . . . . . 7 65 3.1. Dispatch Header . . . . . . . . . . . . . . . . . . . . . 8 66 4. 6LoWPAN addressing . . . . . . . . . . . . . . . . . . . . . 9 67 4.1. Stateless Address Autoconfiguration of routable IPv6 68 addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 69 4.2. IPv6 Link Local Address . . . . . . . . . . . . . . . . . 9 70 4.3. Unicast Address Mapping . . . . . . . . . . . . . . . . . 10 71 4.4. On the use of Neighbor Discovery technologies . . . . . . 10 72 4.4.1. Prefix and CID management (Route-over) . . . . . . . 11 73 4.4.2. Prefix and CID management (Mesh-under) . . . . . . . 11 74 5. Header Compression . . . . . . . . . . . . . . . . . . . . . 12 75 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 76 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 77 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 13 78 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 79 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 80 10.1. Normative References . . . . . . . . . . . . . . . . . . 14 81 10.2. Informative References . . . . . . . . . . . . . . . . . 15 82 Appendix A. G.9959 6LoWPAN datagram example . . . . . . . . . . 16 83 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19 84 B.1. Changes since -00 . . . . . . . . . . . . . . . . . . . . 19 85 B.2. Changes since -01 . . . . . . . . . . . . . . . . . . . . 20 86 B.3. Changes since -02 . . . . . . . . . . . . . . . . . . . . 20 87 B.4. Changes since -03 . . . . . . . . . . . . . . . . . . . . 21 88 B.5. Changes since -04 . . . . . . . . . . . . . . . . . . . . 21 89 B.6. Changes since -05 . . . . . . . . . . . . . . . . . . . . 21 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 92 1. Introduction 94 The ITU-T G.9959 recommendation [G.9959] targets low-power Personal 95 Area Networks (PANs). This document defines the frame format for 96 transmission of IPv6 [RFC2460] packets as well as the formation of 97 IPv6 link-local addresses and statelessly autoconfigured IPv6 98 addresses on G.9959 networks. 100 The general approach is to adapt elements of [RFC4944] to G.9959 101 networks. G.9959 provides a Segmentation and Reassembly (SAR) layer 102 for transmission of datagrams larger than the G.9959 MAC PDU. 104 [RFC6775] updates [RFC4944] by specifying 6LoWPAN optimizations for 105 IPv6 Neighbor Discovery (ND) (originally defined by [RFC4861]). This 106 document limits the use of [RFC6775] to prefix and Context ID 107 assignment. An IID may be constructed from a G.9959 link-layer 108 address, leading to a "link-layer-derived IPv6 address". If using 109 that method, Duplicate Address Detection (DAD) is not needed. 110 Alternatively, IPv6 addresses may be assigned centrally via DHCP, 111 leading to a "non-link-layer-derived IPv6 address". Address 112 registration is only needed in certain cases. 114 In addition to IPv6 application communication, the frame format 115 defined in this document may be used by IPv6 routing protocols such 116 as RPL [RFC6550] or P2P-RPL [RFC6997] to implement IPv6 routing over 117 G.9959 networks. 119 The encapsulation frame defined by this specification may optionally 120 be transported via mesh routing below the 6LoWPAN layer. Mesh-under 121 and route-over routing protocol specifications are out of scope of 122 this document. 124 1.1. Terms used 126 6LoWPAN: IPv6-based Low-power Personal Area Network 128 ABR: Authoritative 6LBR ([RFC6775]) 130 Ack: Acknowedgement 132 AES: Advanced Encryption Scheme 134 CID: Context Identifier ([RFC6775]) 136 DAD: Duplicate Address Detection ([RFC6775]) 138 DHCPv6: Dynamic Host Configuration Protocol for IPv6 ([RFC3315]) 140 EUI-64: Extended Unique Identifier ([EUI64]) 142 G.9959: Short range, narrow-band digital radiocommunication 143 transceiver ([G.9959]) 144 GHC: Generic Header Compression ([RFC_TBD_GHC]) 146 HomeID: G.9959 Link-Layer Network Identifier 148 IID: Interface IDentifier 150 Link-layer-derived address: IPv6 Address constructed on basis of link 151 layer address information 153 MAC: Media Access Control 155 Mesh-under: Forwarding via mesh routing below the 6LoWPAN layer 157 MTU: Maximum Transmission Unit 159 ND: Neighbor discovery ([RFC4861], [RFC6775]) 161 NodeID: G.9959 Link-Layer Node Identifier 163 Non-link-layer-derived address: IPv6 Address assigned by a managed 164 process, e.g. DHCPv6. 166 NVM: Non-volatile Memory 168 P2P-RPL: Reactive Discovery of Point-to-Point Routes in Low-Power and 169 Lossy Networks ([RFC6997]) 171 PAN: Personal Area Network 173 PDU: Protocol Data Unit 175 PHY: Physical Layer 177 RA: Router Advertisement ([RFC4861], [RFC6775]) 179 Route-over: Forwarding via IP routing above the 6LoWPAN layer 181 RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks 182 ([RFC6550]) 184 SAR: G.9959 Segmentation And Reassembly 186 ULA: Unique Local Address [RFC4193] 188 2. G.9959 parameters to use for IPv6 transport 190 This chapter outlines properties applying to the PHY and MAC of 191 G.9959 and how to use these for IPv6 transport. 193 2.1. Addressing mode 195 G.9959 defines how a unique 32-bit HomeID network identifier is 196 assigned by a network controller and how an 8-bit NodeID host 197 identifier is allocated to each node. NodeIDs are unique within the 198 network identified by the HomeID. The G.9959 HomeID represents an 199 IPv6 subnet which is identified by one or more IPv6 prefixes. 201 An IPv6 host MUST construct its link-local IPv6 address from the 202 link-layer-derived IID in order to facilitate IP header compression 203 as described in [RFC6282]. 205 A node interface MAY support the M flag of the RA message for the 206 construction of routable IPv6 addresses. A cost optimized node 207 implementation may save memory by skipping support for the M flag. 208 The M flag MUST be interpreted as defined in Figure 1. 210 +--------+--------+---------------------------------------------+ 211 | M Flag | M flag | Required node behavior | 212 | support| value | | 213 +--------+--------+---------------------------------------------+ 214 | No |(ignore)| Node MUST use link-layer-derived addressing | 215 +--------+--------+---------------------------------------------+ 216 | Yes | 0 | Node MUST use link-layer-derived addressing | 217 | +--------+---------------------------------------------+ 218 | | 1 | Node MUST use DHCPv6 based addressing and | 219 | | | Node MUST comply fully with [RFC6775] | 220 +--------+--------+---------------------------------------------+ 222 Figure 1: RA M flag support and interpretation 224 A node that uses DHCPv6 based addressing MUST comply fully with the 225 text of [RFC6775]. 227 A word of caution: since HomeIDs and NodeIDs are handed out by a 228 network controller function during inclusion, identifier validity and 229 uniqueness is limited by the lifetime of the network membership. 230 This can be cut short by a mishap occurring to the network 231 controller. Having a single point of failure at the network 232 controller suggests that high-reliability network deployments may 233 benefit from a redundant network controller function. 235 This warning applies to link-layer-derived addressing as well as to 236 non-link-layer-derived addressing deployments. 238 2.2. IPv6 Multicast support 240 [RFC3819] recommends that IP subnetworks support (subnet-wide) 241 multicast. G.9959 supports direct-range IPv6 multicast while subnet- 242 wide multicast is not supported natively by G.9959. Subnet-wide 243 multicast may be provided by an IP routing protocol or a mesh routing 244 protocol operating below the 6LoWPAN layer. Routing protocol 245 specifications are out of scope of this document. 247 IPv6 multicast packets MUST be carried via G.9959 broadcast. 249 As per [G.9959], this is accomplished as follows: 251 1. The destination HomeID of the G.9959 MAC PDU MUST be the HomeID 252 of the network 254 2. The destination NodeID of the G.9959 MAC PDU MUST be the 255 broadcast NodeID (0xff) 257 G.9959 broadcast MAC PDUs are only intercepted by nodes within the 258 network identified by the HomeID. 260 2.3. G.9959 MAC PDU size and IPv6 MTU 262 IPv6 packets MUST be transmitted using G.9959 transmission profile R3 263 or higher. 265 [RFC2460] specifies that any link that cannot convey a 1280-octet 266 packet in one piece, must provide link-specific fragmentation and 267 reassembly at a layer below IPv6. 269 G.9959 provides Segmentation And Reassembly for payloads up to 1350 270 octets. IPv6 Header Compression [RFC6282] improves the chances that 271 a short IPv6 packet can fit into a single G.9959 frame. Therefore, 272 section Section 3 specifies that [RFC6282] MUST be supported. With 273 the mandatory link-layer security enabled, a G.9959 R3 MAC PDU may 274 accommodate 6LoWPAN datagrams of up to 130 octets without triggering 275 G.9959 Segmentation and Reassembly (SAR). Longer 6LoWPAN datagrams 276 will lead to the transmission of multiple G.9959 PDUs. 278 2.4. Transmission status indications 280 The G.9959 MAC layer provides native acknowledgement and 281 retransmission of MAC PDUs. The G.9959 SAR layer does the same for 282 larger datagrams. A mesh routing layer may provide a similar feature 283 for routed communication. An IPv6 routing stack communicating over 284 G.9959 may utilize link-layer status indications such as delivery 285 confirmation and Ack timeout from the MAC layer. 287 2.5. Transmission security 289 Implementations claiming conformance with this document MUST enable 290 G.9959 shared network key security. 292 The shared network key is intended to address security requirements 293 in the home at the normal security requirements level. For 294 applications with high or very high requirements on confidentiality 295 and/or integrity, additional application layer security measures for 296 end-to-end authentication and encryption may need to be applied. 297 (The availability of the network relies on the security properties of 298 the network key in any case) 300 3. 6LoWPAN Adaptation Layer and Frame Format 302 The 6LoWPAN encapsulation formats defined in this chapter are carried 303 as payload in the G.9959 MAC PDU. IPv6 header compression [RFC6282] 304 MUST be supported by implementations of this specification. Further, 305 implementations MAY support Generic Header Compression (GHC) 306 [RFC_TBD_GHC]. A node implementing [RFC_TBD_GHC] MUST probe its 307 peers for GHC support before applying GHC compression. 309 All 6LoWPAN datagrams transported over G.9959 are prefixed by a 310 6LoWPAN encapsulation header stack. The 6LoWPAN payload follows this 311 encapsulation header stack. Each header in the header stack contains 312 a header type followed by zero or more header fields. An IPv6 header 313 stack may contain, in the following order, addressing, hop-by-hop 314 options, routing, fragmentation, destination options, and finally 315 payload [RFC2460]. The 6LoWPAN header format is structured the same 316 way. Currently only one payload option is defined for the G.9959 317 6LoWPAN header format. 319 The definition of 6LoWPAN headers consists of the dispatch value, the 320 definition of the header fields that follow, and their ordering 321 constraints relative to all other headers. Although the header stack 322 structure provides a mechanism to address future demands on the 323 6LoWPAN adaptation layer, it is not intended to provide general 324 purpose extensibility. 326 An example of a complete G.9959 6LoWPAN datagram can be found in 327 Appendix A. 329 3.1. Dispatch Header 331 The dispatch header is shown below: 333 0 1 2 3 334 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | 6LoWPAN CmdCls| Dispatch | Type-specific header | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 Figure 2: Dispatch Type and Header 341 6LoWPAN CmdCls: 6LoWPAN Command Class identifier. This field MUST 342 carry the value 0x4F [G.9959]. The value is assigned by the ITU-T 343 and specifies that the following bits are a 6LoWPAN encapsulated 344 datagram. 6LoWPAN protocols MUST ignore the G.9959 frame if the 345 6LoWPAN Command Class identifier deviates from 0x4F. 347 Dispatch: Identifies the header type immediately following the 348 Dispatch Header. 350 Type-specific header: A header determined by the Dispatch Header. 352 The dispatch value may be treated as an unstructured namespace. Only 353 a few symbols are required to represent current 6LoWPAN 354 functionality. Although some additional savings could be achieved by 355 encoding additional functionality into the dispatch byte, these 356 measures would tend to constrain the ability to address future 357 alternatives. 359 Dispatch values used in this specification are compatible with the 360 dispatch values defined by [RFC4944] and [RFC6282]. 362 +------------+------------------------------------------+-----------+ 363 | Pattern | Header Type | Reference | 364 +------------+------------------------------------------+-----------+ 365 | 01 1xxxxx | 6LoWPAN_IPHC - Compressed IPv6 Addresses | [RFC6282] | 366 +------------+------------------------------------------+-----------+ 367 All other Dispatch values are unassigned in this document. 369 Figure 3: Dispatch values 371 6LoWPAN_IPHC: IPv6 Header Compression. Refer to [RFC6282]. 373 4. 6LoWPAN addressing 375 IPv6 addresses may be autoconfigured from IIDs which may again be 376 constructed from link-layer address information to save memory in 377 devices and to facilitate efficient IP header compression as per 378 [RFC6282]. Link-layer-derived addresses have a static nature and may 379 involuntarily expose private usage data on public networks. Refer to 380 Section 8. 382 A NodeID is mapped into an IEEE EUI-64 identifier as follows: 384 IID = 0000:00ff:fe00:YYXX 386 Figure 4: Constructing a compressible IID 388 where XX carries the G.9959 NodeID and YY is a one byte value chosen 389 by the individual node. The default YY value MUST be zero. A node 390 MAY use other values of YY than zero to form additional IIDs in order 391 to instantiate multiple IPv6 interfaces. The YY value MUST be 392 ignored when computing the corresponding NodeID (the XX value) from 393 an IID. 395 The method of constructing IIDs from the link-layer address obviously 396 does not support addresses assigned or constructed by other means. A 397 node MUST NOT compute the NodeID from the IID if the first 6 bytes of 398 the IID do not comply with the format defined in Figure 4. In that 399 case, the address resolution mechanisms of RFC 6775 apply. 401 4.1. Stateless Address Autoconfiguration of routable IPv6 addresses 403 The IID defined above MUST be used whether autoconfiguring a ULA IPv6 404 address [RFC4193] or a globally routable IPv6 address [RFC3587] in 405 G.9959 subnets. 407 4.2. IPv6 Link Local Address 409 The IPv6 link-local address [RFC4291] for a G.9959 interface is 410 formed by appending the IID defined above to the IPv6 link local 411 prefix FE80::/64. 413 The "Universal/Local" (U/L) bit MUST be set to zero in keeping with 414 the fact that this is not a globally unique value [EUI64]. 416 The resulting link local address is formed as follows: 418 10 bits 54 bits 64 bits 419 +----------+-----------------------+----------------------------+ 420 |1111111010| (zeros) | Interface Identifier (IID) | 421 +----------+-----------------------+----------------------------+ 423 Figure 5: IPv6 Link Local Address 425 4.3. Unicast Address Mapping 427 The address resolution procedure for mapping IPv6 unicast addresses 428 into G.9959 link-layer addresses follows the general description in 429 Section 7.2 of [RFC4861]. The Source/Target Link-layer Address 430 option MUST have the following form when the link layer is G.9959. 432 0 1 433 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 434 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 435 | Type | Length=1 | 436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 | 0x00 | NodeID | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Padding | 440 +- -+ 441 | (All zeros) | 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 444 Figure 6: IPv6 Unicast Address Mapping 446 Option fields: 448 Type: The value 1 signifies the Source Link-layer address. The value 449 2 signifies the Destination Link-layer address. 451 Length: This is the length of this option (including the type and 452 length fields) in units of 8 octets. The value of this field is 453 always 1 for G.9959 NodeIDs. 455 NodeID: This is the G.9959 NodeID the actual interface currently 456 responds to. The link-layer address may change if the interface 457 joins another network at a later time. 459 4.4. On the use of Neighbor Discovery technologies 461 [RFC4861] specifies how IPv6 nodes may resolve link layer addresses 462 from IPv6 addresses via the use of link-local IPv6 multicast. 463 [RFC6775] is an optimization of [RFC4861], specifically targeting 464 6LoWPAN networks. [RFC6775] defines how a 6LoWPAN node may register 465 IPv6 addresses with an authoritative border router (ABR). Mesh-under 466 networks MUST NOT use [RFC6775] address registration. However, 467 [RFC6775] address registration MUST be used if the first 6 bytes of 468 the IID do not comply with the format defined in Figure 3. 470 4.4.1. Prefix and CID management (Route-over) 472 In route-over environments, IPv6 hosts MUST use [RFC6775] address 473 registration. A node implementation for route-over operation MAY use 474 RFC6775 mechanisms for obtaining IPv6 prefixes and corresponding 475 header compression context information [RFC6282]. RFC6775 Route-over 476 requirements apply with no modifications. 478 4.4.2. Prefix and CID management (Mesh-under) 480 An implementation for mesh-under operation MUST use [RFC6775] 481 mechanisms for managing IPv6 prefixes and corresponding header 482 compression context information [RFC6282]. [RFC6775] Duplicate 483 Address Detection (DAD) MUST NOT be used, since the link-layer 484 inclusion process of G.9959 ensures that a NodeID is unique for a 485 given HomeID. 487 With this exception and the specific redefinition of the RA Router 488 Lifetime value 0xFFFF (refer to Section 4.4.2.3), the text of the 489 following subsections is in compliance with [RFC6775]. 491 4.4.2.1. Prefix assignment considerations 493 As stated by [RFC6775], an ABR is responsible for managing 494 prefix(es). Global routable prefixes may change over time. It is 495 RECOMMENDED that a ULA prefix is assigned to the 6LoWPAN subnet to 496 facilitate stable site-local application associations based on IPv6 497 addresses. A node MAY support the M flag of the RA message. This 498 influences the way IPv6 addresses are assigned. Refer to Section 2.1 499 for details. 501 4.4.2.2. Robust and efficient CID management 503 The 6LoWPAN Context Option (6CO) is used according to [RFC6775] in an 504 RA to disseminate Context IDs (CID) to use for compressing prefixes. 505 One or more prefixes and corresponding Context IDs MUST be assigned 506 during initial node inclusion. 508 When updating context information, a CID may have its lifetime set to 509 zero to obsolete it. The CID MUST NOT be reused immediately; rather 510 the next vacant CID should be assigned. Header compression based on 511 CIDs MUST NOT be used for RA messages carrying Context Information. 513 An expired CID and the associated prefix MUST NOT be reset but rather 514 retained in receive-only mode if there is no other current need for 515 the CID value. This will allow an ABR to detect if a sleeping node 516 without clock uses an expired CID and in response, the ABR MUST 517 return an RA with fresh Context Information to the originator. 519 4.4.2.3. Infinite prefix lifetime support for island-mode networks 521 Nodes MUST renew the prefix and CID according to the lifetime 522 signaled by the ABR. [RFC6775] specifies that the maximum value of 523 the RA Router Lifetime field MAY be up to 0xFFFF. This document 524 further specifies that the value 0xFFFF MUST be interpreted as 525 infinite lifetime. This value MUST NOT be used by ABRs. Its use is 526 only intended for a sleeping network controller; for instance a 527 battery powered remote control being master for a small island-mode 528 network of light modules. 530 5. Header Compression 532 IPv6 header compression MUST be implemented according to [RFC6282]. 533 This section will simply identify substitutions that should be made 534 when interpreting the text of [RFC6282]. 536 In general the following substitutions should be made: 538 o Replace "802.15.4" with "G.9959" 540 o Replace "802.15.4 short address" with "" 542 o Replace "802.15.4 PAN ID" with "G.9959 HomeID" 544 When a 16-bit address is called for (i.e., an IEEE 802.15.4 "short 545 address") it MUST be formed by prepending an Interface label byte to 546 the G.9959 NodeID: 548 0 1 549 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | Interface | NodeID | 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 554 A transmitting node may be sending to an IPv6 destination address 555 which can be reconstructed from the link-layer destination address. 556 If the Interface number is zero (the default value), all IPv6 address 557 bytes may be elided. Likewise, the Interface number of a fully 558 elided IPv6 address (i.e. SAM/DAM=11) may be reconstructed to the 559 value zero by a receiving node. 561 64 bit 802.15.4 address details do not apply. 563 6. IANA Considerations 565 This document makes no request of IANA. 567 Note to RFC Editor: this section may be removed on publication as an 568 RFC. 570 7. Security Considerations 572 The method of derivation of Interface Identifiers from 8-bit NodeIDs 573 preserves uniqueness within the network. However, there is no 574 protection from duplication through forgery. Neighbor Discovery in 575 G.9959 links may be susceptible to threats as detailed in [RFC3756]. 576 G.9959 networks may feature mesh routing. This implies additional 577 threats due to ad hoc routing as per [KW03]. G.9959 provides 578 capability for link-layer security. G.9959 nodes MUST use link-layer 579 security with a shared key. Doing so will alleviate the majority of 580 threats stated above. A sizeable portion of G.9959 devices is 581 expected to always communicate within their PAN (i.e., within their 582 subnet, in IPv6 terms). In response to cost and power consumption 583 considerations, these devices will typically implement the minimum 584 set of features necessary. Accordingly, security for such devices 585 may rely on the mechanisms defined at the link layer by G.9959. 586 G.9959 relies on the Advanced Encryption Standard (AES) for 587 authentication and encryption of G.9959 frames and further employs 588 challenge-response handshaking to prevent replay attacks. 590 It is also expected that some G.9959 devices (e.g. billing and/or 591 safety critical products) will implement coordination or integration 592 functions. These may communicate regularly with IPv6 peers outside 593 the subnet. Such IPv6 devices are expected to secure their end-to- 594 end communications with standard security mechanisms (e.g., IPsec, 595 TLS, etc). 597 8. Privacy Considerations 599 IP addresses may be used to track devices on the Internet, which in 600 turn can be linked to individuals and their activities. Depending on 601 the application and the actual use pattern, this may be undesirable. 602 To impede tracking, globally unique and non-changing characteristics 603 of IP addresses should be avoided, e.g. by frequently changing the 604 global prefix and avoiding unique link-layer-derived IIDs in 605 addresses. 607 Some link layers use a 48-bit or a 64-bit link layer address which 608 uniquely identifies the node on a global scale regardless of global 609 prefix changes. The risk of exposing a G.9959 device from its link- 610 layer-derived IID is limited because of the short 8-bit link layer 611 address. 613 While intended for central address management, DHCPv6 address 614 assignment also decouples the IPv6 address from the link layer 615 address. Addresses may be made dynamic by the use of a short DHCP 616 lease period and an assignment policy which makes the DHCP server 617 hand out a fresh IP address every time. 619 It should be noted that privacy and frequently changing address 620 assignment comes at a cost. Non-link-layer-derived IIDs require the 621 use of address registration and further, non-link-layer-derived IIDs 622 cannot be compressed, which leads to longer datagrams and increased 623 link layer segmentation. Finally, frequent prefix changes 624 necessitate more Context Identifier updates, which not only leads to 625 increased traffic but also may affect the battery lifetime of 626 sleeping nodes. 628 9. Acknowledgements 630 Thanks to the authors of RFC 4944 and RFC 6282 and members of the 631 IETF 6LoWPAN working group; this document borrows extensively from 632 their work. Thanks to Erez Ben-Tovim, Erik Nordmark, Kerry Lynn, 633 Michael Richardson, Tommas Jess Christensen for useful comments. 634 Thanks to Carsten Bormann for extensive feedback which improved this 635 document significantly. Thanks to Brian Haberman for pointing out 636 unclear details. 638 10. References 640 10.1. Normative References 642 [G.9959] "G.9959 (02/12) + G.9959 Amendment 1 (10/13): Short range, 643 narrow-band digital radiocommunication transceivers", 644 February 2012. 646 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 647 Requirement Levels", BCP 14, RFC 2119, March 1997. 649 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 650 (IPv6) Specification", RFC 2460, December 1998. 652 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 653 Addresses", RFC 4193, October 2005. 655 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 656 Architecture", RFC 4291, February 2006. 658 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 659 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 660 September 2007. 662 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 663 "Transmission of IPv6 Packets over IEEE 802.15.4 664 Networks", RFC 4944, September 2007. 666 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 667 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 668 September 2011. 670 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 671 "Neighbor Discovery Optimization for IPv6 over Low-Power 672 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 673 November 2012. 675 [RFC_TBD_GHC] 676 "draft-ietf-6lo-ghc: 6LoWPAN Generic Compression of 677 Headers and Header-like Payloads", September 2014. 679 10.2. Informative References 681 [EUI64] IEEE, "GUIIDELINES FOR 64-BIT GLOBAL IDENTIFIER (EUI-64) 682 REGISTRATION AUTHORITY", IEEE Std http:// 683 standards.ieee.org/regauth/oui/tutorials/EUI64.html, 684 November 2012. 686 [KW03] Elsevier's AdHoc Networks Journal, ""Secure Routing in 687 Sensor Networks: Attacks and Countermeasures", Special 688 Issue on Sensor Network Applications and Protocols vol 1, 689 issues 2-3", , September 2003. 691 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 692 and M. Carney, "Dynamic Host Configuration Protocol for 693 IPv6 (DHCPv6)", RFC 3315, July 2003. 695 [RFC3587] Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global 696 Unicast Address Format", RFC 3587, August 2003. 698 [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor 699 Discovery (ND) Trust Models and Threats", RFC 3756, May 700 2004. 702 [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., 703 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 704 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 705 RFC 3819, July 2004. 707 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 708 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 709 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 710 Lossy Networks", RFC 6550, March 2012. 712 [RFC6997] Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J. 713 Martocci, "Reactive Discovery of Point-to-Point Routes in 714 Low-Power and Lossy Networks", RFC 6997, August 2013. 716 Appendix A. G.9959 6LoWPAN datagram example 718 This example outlines each individual bit of a sample IPv6 UDP packet 719 arriving to a G.9959 node from a host in the Internet via a PAN 720 border router. 722 In the G.9959 PAN, the complete frame has the following fields. 724 G.9959: 726 +------+---------+----------+---+-----+----------... 727 |HomeID|SrcNodeID|FrmControl|Len|SeqNo|DestNodeID| 728 +------+---------+----------+---+-----+----------+-... 730 6LoWPAN: 732 ...+--------------+----------------+-----------------------... 733 |6LoWPAN CmdCls|6LoWPAN_IPHC Hdr|Compressed IPv6 headers| 734 ...-------------+----------------+-----------------------+-... 736 6LoWPAN, TCP/UDP, App payload: 738 ...+-------------------------+------------+-----------+ 739 |Uncompressed IPv6 headers|TCP/UDP/ICMP|App payload| 740 ...------------------------+------------+-----------+ 742 The frame comes from the source IPv6 address 743 2001:0db8:ac10:ef01::ff:fe00:1206. The source prefix 744 2001:0db8:ac10:ef01/64 is identified by the IPHC CID = 3. 746 The frame is delivered in direct range from the gateway which has 747 source NodeID = 1. The Interface Identifier (IID) ff:fe00:1206 is 748 recognised as a link-layer-derived address and is compressed to the 749 16 bit value 0x1206. 751 The frame is sent to the destination IPv6 address 752 2001:0db8:27ef:42ca::ff:fe00:0004. The destination prefix 753 2001:0db8:27ef:42ca/64 is identified by the IPHC CID = 2. 755 The Interface Identifier (IID) ff:fe00:0004 is recognised as a link- 756 layer-derived address. 758 Thanks to the link-layer-derived addressing rules, the sender knows 759 that this is to be sent to G.9959 NodeID = 4; targeting the IPv6 760 interface instance number 0 (the default). 762 To reach the 6LoWPAN stack of the G.9959 node, (skipping the G.9959 763 header fields) the first octet must be the 6LoWPAN Command Class 764 (0x4F). 766 0 767 0 1 2 3 4 5 6 7 8 768 +-+-+-+-+-+-+-+-... 769 | 0x4F | 770 +-+-+-+-+-+-+-+-+-... 772 The Dispatch header bits '011' advertises a compressed IPv6 header. 774 0 1 775 0 1 2 3 4 5 6 7 8 9 0 776 +-+-+-+-+-+-+-+-+-+-+-... 777 | 0x4F |0 1 1 778 +-+-+-+-+-+-+-+-+-+-+-+-... 780 The following bits encode the first IPv6 header fields: 782 TF = '11' : Traffic Class and Flow Label are elided. 783 NH = '1' : Next Header is elided 784 HLIM = '10' : Hop limit is 64 786 0 1 787 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 788 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 789 | 0x4F |0 1 1 1 1 1 1 0| 790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 792 CID = '1' : CI data follows the DAM field 793 SAC = '1' : Src addr uses stateful, context-based compression 794 SAM = '10' : Use src CID and 16 bits for link-layer-derived addr 795 M = '0' : Dest addr is not a multicast addr 796 DAC = '1' : Dest addr uses stateful, context-based compression 797 DAM = '11' : Use dest CID and dest NodeID to link-layer-derived addr 799 0 1 2 800 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 801 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 802 | 0x4F |0 1 1 1 1 1 1 0|1 1 1 0 0 1 1 1| 803 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 805 Address compression context identifiers: 807 SCI = 0x3 808 DCI = 0x2 810 2 3 811 4 5 6 7 8 9 0 1 812 ...+-+-+-+-+-+-+-+-... 813 | 0x3 | 0x2 | 814 ...+-+-+-+-+-+-+-+-... 816 IPv6 header fields: 817 (skipping "version" field) 818 (skipping "Traffic Class") 819 (skipping "flow label") 820 (skipping "payload length") 822 IPv6 header address fields: 824 SrcIP = 0x1206 : Use SCI and 16 LS bits of link-layer-derived address 826 (skipping DestIP ) - completely reconstructed from Dest NodeID and DCI 828 2 3 4 829 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 830 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 831 | 0x3 | 0x2 | 0x12 | 0x06 | 832 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 834 Next header encoding for the UDP header: 836 Dispatch = '11110': Next Header dispatch code for UDP header 837 C = '0' : 16 bit checksum carried inline 838 P = '00' : Both src port and dest Port are carried in-line. 840 4 5 841 8 9 0 1 2 3 4 5 842 ...+-+-+-+-+-+-+-+-... 843 |1 1 1 1 0|0|0 0| 844 ...+-+-+-+-+-+-+-+-... 846 UDP header fields: 848 src Port = 0x1234 849 dest port = 0x5678 851 5 6 7 8 852 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 853 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 854 | 0x12 | 0x34 | 0x56 | 0x78 | 855 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.. 857 (skipping "length") 858 checksum = .... (actual checksum value depends on 859 the actual UDP payload) 861 1 862 8 9 0 863 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 864 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 865 | (UDP checksum) | 866 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 868 Add your own UDP payload here... 870 Appendix B. Change Log 872 B.1. Changes since -00 874 o Clarified that mesh-under routing may take place below the 6LoWPAN 875 layer but that specific mesh-under routing protocols are not 876 within the scope of this doc. 878 o Clarified that RFC6282 IPv6 Header Compression MUST be supported. 880 o Clarified the text of section 5.4 on the use of RFC6775 address 881 registration in mesh-under networks. 883 o Split 5.4.2 into multiple paragraphs. 885 B.2. Changes since -01 887 o Added this Change Log 889 o Editorial nits. 891 o Made IPv6 Header Compression mandatory. Therefore, the Dispatch 892 value "01 000001 - Uncompressed IPv6 Addresses" was removed from 893 figure 2. 895 o Changed SHOULD to MUST: An IPv6 host SHOULD construct its link- 896 local IPv6 address and routable IPv6 addresses from the NodeID in 897 order to facilitate IP header compression as described in 898 [RFC6282]. 900 o Changed SHOULD NOT to MUST NOT: Mesh-under networks MUST NOT use 901 [RFC6775] address registration. 903 o Changed SHOULD NOT to MUST NOT: [RFC6775] Duplicate Address 904 Detection (DAD) MUST NOT be used. 906 o Changed SHOULD NOT to MUST NOT: The CID MUST NOT be reused 907 immediately; 909 o Changed SHOULD NOT to MUST NOT: An expired CID and the associated 910 prefix MUST NOT be reset but rather retained in receive-only mode 912 o Changed LBR -> ABR 914 o Changed SHOULD to MUST: , the ABR MUST return an RA with fresh 915 Context Information to the originator. 917 o Changed SHOULD NOT to MUST NOT: This value MUST NOT be used by 918 ABRs. Its use is only intended for a sleeping network controller. 920 B.3. Changes since -02 922 o Editorial nits. 924 o Moved text to the right section so that it does not prohibit DAD 925 for Route-Over deployments. 927 o Introduced RA M flag support so that nodes may be instructed to 928 use DHCPv6 for centralized address assignment. 930 o Added example appendix: Complete G.9959 6LoWPAN datagram 931 composition with CID-based header compression. 933 B.4. Changes since -03 935 o Corrected error in 6LoWPAN datagram example appendix: 64 hop limit 936 in comment => also 64 hop limit in actual frame format. 938 o Added section "Privacy Considerations" 940 B.5. Changes since -04 942 o Text on RA M flag support was replaced with a table to improve 943 clarity. 945 o Added further details to text on achieving privacy addressing with 946 DHCP. 948 B.6. Changes since -05 950 o Term ABR now points to Authoritative 6LBR as defined by RFC6775. 952 o Removed sentence "The G.9959 network controller function SHOULD be 953 integrated in the ABR." as this was an implementation guideline 954 with no relevance to network performance. 956 o Clarifying that network controller function redundancy is relevant 957 for network deployers; not user-level application designers. 959 o Clarified that RFC2460 specifies that link layer must provide 960 fragmentation if 1280 octet packets cannot be carried in one piece 961 by the link layer. 963 o Clarified that the 6LoWPAN CmdCls identifier value is assigned by 964 the ITU-T. 966 o Added reference to Privacy Considerations section from 6LoWPAN 967 Addressing section. 969 o Introducing optional GHC header compression. 971 Authors' Addresses 973 Anders Brandt 974 Sigma Designs 975 Emdrupvej 26A, 1. 976 Copenhagen O 2100 977 Denmark 979 Email: anders_brandt@sigmadesigns.com 981 Jakob Buron 982 Sigma Designs 983 Emdrupvej 26A, 1. 984 Copenhagen O 2100 985 Denmark 987 Email: jakob_buron@sigmadesigns.com