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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 26, 2015 September 22, 2014 7 Transmission of IPv6 packets over ITU-T G.9959 Networks 8 draft-ietf-6lo-lowpanz-07 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 26, 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 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 B.7. Changes since -06 . . . . . . . . . . . . . . . . . . . . 22 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 93 1. Introduction 95 The ITU-T G.9959 recommendation [G.9959] targets low-power Personal 96 Area Networks (PANs). This document defines the frame format for 97 transmission of IPv6 [RFC2460] packets as well as the formation of 98 IPv6 link-local addresses and statelessly autoconfigured IPv6 99 addresses on G.9959 networks. 101 The general approach is to adapt elements of [RFC4944] to G.9959 102 networks. G.9959 provides a Segmentation and Reassembly (SAR) layer 103 for transmission of datagrams larger than the G.9959 MAC PDU. 105 [RFC6775] updates [RFC4944] by specifying 6LoWPAN optimizations for 106 IPv6 Neighbor Discovery (ND) (originally defined by [RFC4861]). This 107 document limits the use of [RFC6775] to prefix and Context ID 108 assignment. An IID may be constructed from a G.9959 link-layer 109 address, leading to a "link-layer-derived IPv6 address". If using 110 that method, Duplicate Address Detection (DAD) is not needed. 111 Alternatively, IPv6 addresses may be assigned centrally via DHCP, 112 leading to a "non-link-layer-derived IPv6 address". Address 113 registration is only needed in certain cases. 115 In addition to IPv6 application communication, the frame format 116 defined in this document may be used by IPv6 routing protocols such 117 as RPL [RFC6550] or P2P-RPL [RFC6997] to implement IPv6 routing over 118 G.9959 networks. 120 The encapsulation frame defined by this specification may optionally 121 be transported via mesh routing below the 6LoWPAN layer. Mesh-under 122 and route-over routing protocol specifications are out of scope of 123 this document. 125 1.1. Terms used 127 6LoWPAN: IPv6-based Low-power Personal Area Network 129 ABR: Authoritative 6LBR ([RFC6775]) 131 Ack: Acknowedgement 133 AES: Advanced Encryption Scheme 135 CID: Context Identifier ([RFC6775]) 137 DAD: Duplicate Address Detection ([RFC6775]) 139 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]) 145 GHC: Generic Header Compression ([RFC_TBD_GHC]) 147 HomeID: G.9959 Link-Layer Network Identifier 149 IID: Interface IDentifier 151 Link-layer-derived address: IPv6 Address constructed on basis of link 152 layer address information 154 MAC: Media Access Control 156 Mesh-under: Forwarding via mesh routing below the 6LoWPAN layer 158 MTU: Maximum Transmission Unit 160 ND: Neighbor discovery ([RFC4861], [RFC6775]) 162 NodeID: G.9959 Link-Layer Node Identifier 164 Non-link-layer-derived address: IPv6 Address assigned by a managed 165 process, e.g. DHCPv6. 167 NVM: Non-volatile Memory 169 P2P-RPL: Reactive Discovery of Point-to-Point Routes in Low-Power and 170 Lossy Networks ([RFC6997]) 172 PAN: Personal Area Network 174 PDU: Protocol Data Unit 176 PHY: Physical Layer 178 RA: Router Advertisement ([RFC4861], [RFC6775]) 180 Route-over: Forwarding via IP routing above the 6LoWPAN layer 182 RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks 183 ([RFC6550]) 185 SAR: G.9959 Segmentation And Reassembly 187 ULA: Unique Local Address [RFC4193] 189 2. G.9959 parameters to use for IPv6 transport 191 This chapter outlines properties applying to the PHY and MAC of 192 G.9959 and how to use these for IPv6 transport. 194 2.1. Addressing mode 196 G.9959 defines how a unique 32-bit HomeID network identifier is 197 assigned by a network controller and how an 8-bit NodeID host 198 identifier is allocated to each node. NodeIDs are unique within the 199 network identified by the HomeID. The G.9959 HomeID represents an 200 IPv6 subnet which is identified by one or more IPv6 prefixes. 202 An IPv6 host MUST construct its link-local IPv6 address from the 203 link-layer-derived IID in order to facilitate IP header compression 204 as described in [RFC6282]. 206 A node interface MAY support the M flag of the RA message for the 207 construction of routable IPv6 addresses. A cost optimized node 208 implementation may save memory by skipping support for the M flag. 209 The M flag MUST be interpreted as defined in Figure 1. 211 +--------+--------+---------------------------------------------+ 212 | M Flag | M flag | Required node behavior | 213 | support| value | | 214 +--------+--------+---------------------------------------------+ 215 | No |(ignore)| Node MUST use link-layer-derived addressing | 216 +--------+--------+---------------------------------------------+ 217 | Yes | 0 | Node MUST use link-layer-derived addressing | 218 | +--------+---------------------------------------------+ 219 | | 1 | Node MUST use DHCPv6 based addressing and | 220 | | | Node MUST comply fully with [RFC6775] | 221 +--------+--------+---------------------------------------------+ 223 Figure 1: RA M flag support and interpretation 225 A node that uses DHCPv6 based addressing MUST comply fully with the 226 text of [RFC6775]. 228 A word of caution: since HomeIDs and NodeIDs are handed out by a 229 network controller function during inclusion, identifier validity and 230 uniqueness is limited by the lifetime of the network membership. 231 This can be cut short by a mishap occurring to the network 232 controller. Having a single point of failure at the network 233 controller suggests that high-reliability network deployments may 234 benefit from a redundant network controller function. 236 This warning applies to link-layer-derived addressing as well as to 237 non-link-layer-derived addressing deployments. 239 2.2. IPv6 Multicast support 241 [RFC3819] recommends that IP subnetworks support (subnet-wide) 242 multicast. G.9959 supports direct-range IPv6 multicast while subnet- 243 wide multicast is not supported natively by G.9959. Subnet-wide 244 multicast may be provided by an IP routing protocol or a mesh routing 245 protocol operating below the 6LoWPAN layer. Routing protocol 246 specifications are out of scope of this document. 248 IPv6 multicast packets MUST be carried via G.9959 broadcast. 250 As per [G.9959], this is accomplished as follows: 252 1. The destination HomeID of the G.9959 MAC PDU MUST be the HomeID 253 of the network 255 2. The destination NodeID of the G.9959 MAC PDU MUST be the 256 broadcast NodeID (0xff) 258 G.9959 broadcast MAC PDUs are only intercepted by nodes within the 259 network identified by the HomeID. 261 2.3. G.9959 MAC PDU size and IPv6 MTU 263 IPv6 packets MUST be transmitted using G.9959 transmission profile R3 264 or higher. 266 [RFC2460] specifies that any link that cannot convey a 1280-octet 267 packet in one piece, must provide link-specific fragmentation and 268 reassembly at a layer below IPv6. 270 G.9959 provides Segmentation And Reassembly for payloads up to 1350 271 octets. IPv6 Header Compression [RFC6282] improves the chances that 272 a short IPv6 packet can fit into a single G.9959 frame. Therefore, 273 section Section 3 specifies that [RFC6282] MUST be supported. With 274 the mandatory link-layer security enabled, a G.9959 R3 MAC PDU may 275 accommodate 6LoWPAN datagrams of up to 130 octets without triggering 276 G.9959 Segmentation and Reassembly (SAR). Longer 6LoWPAN datagrams 277 will lead to the transmission of multiple G.9959 PDUs. 279 2.4. Transmission status indications 281 The G.9959 MAC layer provides native acknowledgement and 282 retransmission of MAC PDUs. The G.9959 SAR layer does the same for 283 larger datagrams. A mesh routing layer may provide a similar feature 284 for routed communication. An IPv6 routing stack communicating over 285 G.9959 may utilize link-layer status indications such as delivery 286 confirmation and Ack timeout from the MAC layer. 288 2.5. Transmission security 290 Implementations claiming conformance with this document MUST enable 291 G.9959 shared network key security. 293 The shared network key is intended to address security requirements 294 in the home at the normal security requirements level. For 295 applications with high or very high requirements on confidentiality 296 and/or integrity, additional application layer security measures for 297 end-to-end authentication and encryption may need to be applied. 298 (The availability of the network relies on the security properties of 299 the network key in any case) 301 3. 6LoWPAN Adaptation Layer and Frame Format 303 The 6LoWPAN encapsulation formats defined in this chapter are carried 304 as payload in the G.9959 MAC PDU. IPv6 header compression [RFC6282] 305 MUST be supported by implementations of this specification. Further, 306 implementations MAY support Generic Header Compression (GHC) 307 [RFC_TBD_GHC]. A node implementing [RFC_TBD_GHC] MUST probe its 308 peers for GHC support before applying GHC compression. 310 All 6LoWPAN datagrams transported over G.9959 are prefixed by a 311 6LoWPAN encapsulation header stack. The 6LoWPAN payload follows this 312 encapsulation header stack. Each header in the header stack contains 313 a header type followed by zero or more header fields. An IPv6 header 314 stack may contain, in the following order, addressing, hop-by-hop 315 options, routing, fragmentation, destination options, and finally 316 payload [RFC2460]. The 6LoWPAN header format is structured the same 317 way. Currently only one payload option is defined for the G.9959 318 6LoWPAN header format. 320 The definition of 6LoWPAN headers consists of the dispatch value, the 321 definition of the header fields that follow, and their ordering 322 constraints relative to all other headers. Although the header stack 323 structure provides a mechanism to address future demands on the 324 6LoWPAN adaptation layer, it is not intended to provide general 325 purpose extensibility. 327 An example of a complete G.9959 6LoWPAN datagram can be found in 328 Appendix A. 330 3.1. Dispatch Header 332 The dispatch header is shown below: 334 0 1 2 3 335 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 1 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | 6LoWPAN CmdCls| Dispatch | Type-specific header | 338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 340 Figure 2: Dispatch Type and Header 342 6LoWPAN CmdCls: 6LoWPAN Command Class identifier. This field MUST 343 carry the value 0x4F [G.9959]. The value is assigned by the ITU-T 344 and specifies that the following bits are a 6LoWPAN encapsulated 345 datagram. 6LoWPAN protocols MUST ignore the G.9959 frame if the 346 6LoWPAN Command Class identifier deviates from 0x4F. 348 Dispatch: Identifies the header type immediately following the 349 Dispatch Header. 351 Type-specific header: A header determined by the Dispatch Header. 353 The dispatch value may be treated as an unstructured namespace. Only 354 a few symbols are required to represent current 6LoWPAN 355 functionality. Although some additional savings could be achieved by 356 encoding additional functionality into the dispatch byte, these 357 measures would tend to constrain the ability to address future 358 alternatives. 360 Dispatch values used in this specification are compatible with the 361 dispatch values defined by [RFC4944] and [RFC6282]. 363 +------------+------------------------------------------+-----------+ 364 | Pattern | Header Type | Reference | 365 +------------+------------------------------------------+-----------+ 366 | 01 1xxxxx | 6LoWPAN_IPHC - Compressed IPv6 Addresses | [RFC6282] | 367 +------------+------------------------------------------+-----------+ 368 All other Dispatch values are unassigned in this document. 370 Figure 3: Dispatch values 372 6LoWPAN_IPHC: IPv6 Header Compression. Refer to [RFC6282]. 374 4. 6LoWPAN addressing 376 IPv6 addresses may be autoconfigured from IIDs which may again be 377 constructed from link-layer address information to save memory in 378 devices and to facilitate efficient IP header compression as per 379 [RFC6282]. Link-layer-derived addresses have a static nature and may 380 involuntarily expose private usage data on public networks. Refer to 381 Section 8. 383 A NodeID is mapped into an IEEE EUI-64 identifier as follows: 385 IID = 0000:00ff:fe00:YYXX 387 Figure 4: Constructing a compressible IID 389 where XX carries the G.9959 NodeID and YY is a one byte value chosen 390 by the individual node. The default YY value MUST be zero. A node 391 MAY use other values of YY than zero to form additional IIDs in order 392 to instantiate multiple IPv6 interfaces. The YY value MUST be 393 ignored when computing the corresponding NodeID (the XX value) from 394 an IID. 396 The method of constructing IIDs from the link-layer address obviously 397 does not support addresses assigned or constructed by other means. A 398 node MUST NOT compute the NodeID from the IID if the first 6 bytes of 399 the IID do not comply with the format defined in Figure 4. In that 400 case, the address resolution mechanisms of RFC 6775 apply. 402 4.1. Stateless Address Autoconfiguration of routable IPv6 addresses 404 The IID defined above MUST be used whether autoconfiguring a ULA IPv6 405 address [RFC4193] or a globally routable IPv6 address [RFC3587] in 406 G.9959 subnets. 408 4.2. IPv6 Link Local Address 410 The IPv6 link-local address [RFC4291] for a G.9959 interface is 411 formed by appending the IID defined above to the IPv6 link local 412 prefix FE80::/64. 414 The "Universal/Local" (U/L) bit MUST be set to zero in keeping with 415 the fact that this is not a globally unique value [EUI64]. 417 The resulting link local address is formed as follows: 419 10 bits 54 bits 64 bits 420 +----------+-----------------------+----------------------------+ 421 |1111111010| (zeros) | Interface Identifier (IID) | 422 +----------+-----------------------+----------------------------+ 424 Figure 5: IPv6 Link Local Address 426 4.3. Unicast Address Mapping 428 The address resolution procedure for mapping IPv6 unicast addresses 429 into G.9959 link-layer addresses follows the general description in 430 Section 7.2 of [RFC4861]. The Source/Target Link-layer Address 431 option MUST have the following form when the link layer is G.9959. 433 0 1 434 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 | Type | Length=1 | 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | 0x00 | NodeID | 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | Padding | 441 +- -+ 442 | (All zeros) | 443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 445 Figure 6: IPv6 Unicast Address Mapping 447 Option fields: 449 Type: The value 1 signifies the Source Link-layer address. The value 450 2 signifies the Destination Link-layer address. 452 Length: This is the length of this option (including the type and 453 length fields) in units of 8 octets. The value of this field is 454 always 1 for G.9959 NodeIDs. 456 NodeID: This is the G.9959 NodeID the actual interface currently 457 responds to. The link-layer address may change if the interface 458 joins another network at a later time. 460 4.4. On the use of Neighbor Discovery technologies 462 [RFC4861] specifies how IPv6 nodes may resolve link layer addresses 463 from IPv6 addresses via the use of link-local IPv6 multicast. 464 [RFC6775] is an optimization of [RFC4861], specifically targeting 465 6LoWPAN networks. [RFC6775] defines how a 6LoWPAN node may register 466 IPv6 addresses with an authoritative border router (ABR). Mesh-under 467 networks MUST NOT use [RFC6775] address registration. However, 468 [RFC6775] address registration MUST be used if the first 6 bytes of 469 the IID do not comply with the format defined in Figure 3. 471 4.4.1. Prefix and CID management (Route-over) 473 In route-over environments, IPv6 hosts MUST use [RFC6775] address 474 registration. A node implementation for route-over operation MAY use 475 RFC6775 mechanisms for obtaining IPv6 prefixes and corresponding 476 header compression context information [RFC6282]. RFC6775 Route-over 477 requirements apply with no modifications. 479 4.4.2. Prefix and CID management (Mesh-under) 481 An implementation for mesh-under operation MUST use [RFC6775] 482 mechanisms for managing IPv6 prefixes and corresponding header 483 compression context information [RFC6282]. [RFC6775] Duplicate 484 Address Detection (DAD) MUST NOT be used, since the link-layer 485 inclusion process of G.9959 ensures that a NodeID is unique for a 486 given HomeID. 488 With this exception and the specific redefinition of the RA Router 489 Lifetime value 0xFFFF (refer to Section 4.4.2.3), the text of the 490 following subsections is in compliance with [RFC6775]. 492 4.4.2.1. Prefix assignment considerations 494 As stated by [RFC6775], an ABR is responsible for managing 495 prefix(es). Global routable prefixes may change over time. It is 496 RECOMMENDED that a ULA prefix is assigned to the 6LoWPAN subnet to 497 facilitate stable site-local application associations based on IPv6 498 addresses. A node MAY support the M flag of the RA message. This 499 influences the way IPv6 addresses are assigned. Refer to Section 2.1 500 for details. 502 4.4.2.2. Robust and efficient CID management 504 The 6LoWPAN Context Option (6CO) is used according to [RFC6775] in an 505 RA to disseminate Context IDs (CID) to use for compressing prefixes. 506 One or more prefixes and corresponding Context IDs MUST be assigned 507 during initial node inclusion. 509 When updating context information, a CID may have its lifetime set to 510 zero to obsolete it. The CID MUST NOT be reused immediately; rather 511 the next vacant CID should be assigned. Header compression based on 512 CIDs MUST NOT be used for RA messages carrying Context Information. 514 An expired CID and the associated prefix MUST NOT be reset but rather 515 retained in receive-only mode if there is no other current need for 516 the CID value. This will allow an ABR to detect if a sleeping node 517 without clock uses an expired CID and in response, the ABR MUST 518 return an RA with fresh Context Information to the originator. 520 4.4.2.3. Infinite prefix lifetime support for island-mode networks 522 Nodes MUST renew the prefix and CID according to the lifetime 523 signaled by the ABR. [RFC6775] specifies that the maximum value of 524 the RA Router Lifetime field MAY be up to 0xFFFF. This document 525 further specifies that the value 0xFFFF MUST be interpreted as 526 infinite lifetime. This value MUST NOT be used by ABRs. Its use is 527 only intended for a sleeping network controller; for instance a 528 battery powered remote control being master for a small island-mode 529 network of light modules. 531 5. Header Compression 533 IPv6 header compression [RFC6282] MUST be implemented and 534 [RFC_TBD_GHC] compression for higher layers MAY be implemented. This 535 section will simply identify substitutions that should be made when 536 interpreting the text of [RFC6282] and [RFC_TBD_GHC]. 538 In general the following substitutions should be made: 540 o Replace "802.15.4" with "G.9959" 542 o Replace "802.15.4 short address" with "" 544 o Replace "802.15.4 PAN ID" with "G.9959 HomeID" 546 When a 16-bit address is called for (i.e., an IEEE 802.15.4 "short 547 address") it MUST be formed by prepending an Interface label byte to 548 the G.9959 NodeID: 550 0 1 551 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 | Interface | NodeID | 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 556 A transmitting node may be sending to an IPv6 destination address 557 which can be reconstructed from the link-layer destination address. 558 If the Interface number is zero (the default value), all IPv6 address 559 bytes may be elided. Likewise, the Interface number of a fully 560 elided IPv6 address (i.e. SAM/DAM=11) may be reconstructed to the 561 value zero by a receiving node. 563 64 bit 802.15.4 address details do not apply. 565 6. IANA Considerations 567 This document makes no request of IANA. 569 Note to RFC Editor: this section may be removed on publication as an 570 RFC. 572 7. Security Considerations 574 The method of derivation of Interface Identifiers from 8-bit NodeIDs 575 preserves uniqueness within the network. However, there is no 576 protection from duplication through forgery. Neighbor Discovery in 577 G.9959 links may be susceptible to threats as detailed in [RFC3756]. 578 G.9959 networks may feature mesh routing. This implies additional 579 threats due to ad hoc routing as per [KW03]. G.9959 provides 580 capability for link-layer security. G.9959 nodes MUST use link-layer 581 security with a shared key. Doing so will alleviate the majority of 582 threats stated above. A sizeable portion of G.9959 devices is 583 expected to always communicate within their PAN (i.e., within their 584 subnet, in IPv6 terms). In response to cost and power consumption 585 considerations, these devices will typically implement the minimum 586 set of features necessary. Accordingly, security for such devices 587 may rely on the mechanisms defined at the link layer by G.9959. 588 G.9959 relies on the Advanced Encryption Standard (AES) for 589 authentication and encryption of G.9959 frames and further employs 590 challenge-response handshaking to prevent replay attacks. 592 It is also expected that some G.9959 devices (e.g. billing and/or 593 safety critical products) will implement coordination or integration 594 functions. These may communicate regularly with IPv6 peers outside 595 the subnet. Such IPv6 devices are expected to secure their end-to- 596 end communications with standard security mechanisms (e.g., IPsec, 597 TLS, etc). 599 8. Privacy Considerations 601 IP addresses may be used to track devices on the Internet, which in 602 turn can be linked to individuals and their activities. Depending on 603 the application and the actual use pattern, this may be undesirable. 604 To impede tracking, globally unique and non-changing characteristics 605 of IP addresses should be avoided, e.g. by frequently changing the 606 global prefix and avoiding unique link-layer-derived IIDs in 607 addresses. 609 Some link layers use a 48-bit or a 64-bit link layer address which 610 uniquely identifies the node on a global scale regardless of global 611 prefix changes. The risk of exposing a G.9959 device from its link- 612 layer-derived IID is limited because of the short 8-bit link layer 613 address. 615 While intended for central address management, DHCPv6 address 616 assignment also decouples the IPv6 address from the link layer 617 address. Addresses may be made dynamic by the use of a short DHCP 618 lease period and an assignment policy which makes the DHCP server 619 hand out a fresh IP address every time. 621 It should be noted that privacy and frequently changing address 622 assignment comes at a cost. Non-link-layer-derived IIDs require the 623 use of address registration and further, non-link-layer-derived IIDs 624 cannot be compressed, which leads to longer datagrams and increased 625 link layer segmentation. Finally, frequent prefix changes 626 necessitate more Context Identifier updates, which not only leads to 627 increased traffic but also may affect the battery lifetime of 628 sleeping nodes. 630 9. Acknowledgements 632 Thanks to the authors of RFC 4944 and RFC 6282 and members of the 633 IETF 6LoWPAN working group; this document borrows extensively from 634 their work. Thanks to Erez Ben-Tovim, Erik Nordmark, Kerry Lynn, 635 Michael Richardson, Tommas Jess Christensen for useful comments. 636 Thanks to Carsten Bormann for extensive feedback which improved this 637 document significantly. Thanks to Brian Haberman for pointing out 638 unclear details. 640 10. References 642 10.1. Normative References 644 [G.9959] "G.9959 (02/12) + G.9959 Amendment 1 (10/13): Short range, 645 narrow-band digital radiocommunication transceivers", 646 February 2012. 648 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 649 Requirement Levels", BCP 14, RFC 2119, March 1997. 651 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 652 (IPv6) Specification", RFC 2460, December 1998. 654 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 655 Addresses", RFC 4193, October 2005. 657 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 658 Architecture", RFC 4291, February 2006. 660 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 661 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 662 September 2007. 664 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 665 "Transmission of IPv6 Packets over IEEE 802.15.4 666 Networks", RFC 4944, September 2007. 668 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 669 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 670 September 2011. 672 [RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann, 673 "Neighbor Discovery Optimization for IPv6 over Low-Power 674 Wireless Personal Area Networks (6LoWPANs)", RFC 6775, 675 November 2012. 677 [RFC_TBD_GHC] 678 "draft-ietf-6lo-ghc: 6LoWPAN Generic Compression of 679 Headers and Header-like Payloads", September 2014. 681 10.2. Informative References 683 [EUI64] IEEE, "GUIIDELINES FOR 64-BIT GLOBAL IDENTIFIER (EUI-64) 684 REGISTRATION AUTHORITY", IEEE Std http:// 685 standards.ieee.org/regauth/oui/tutorials/EUI64.html, 686 November 2012. 688 [KW03] Elsevier's AdHoc Networks Journal, ""Secure Routing in 689 Sensor Networks: Attacks and Countermeasures", Special 690 Issue on Sensor Network Applications and Protocols vol 1, 691 issues 2-3", , September 2003. 693 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 694 and M. Carney, "Dynamic Host Configuration Protocol for 695 IPv6 (DHCPv6)", RFC 3315, July 2003. 697 [RFC3587] Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global 698 Unicast Address Format", RFC 3587, August 2003. 700 [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor 701 Discovery (ND) Trust Models and Threats", RFC 3756, May 702 2004. 704 [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., 705 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 706 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 707 RFC 3819, July 2004. 709 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 710 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 711 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 712 Lossy Networks", RFC 6550, March 2012. 714 [RFC6997] Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J. 715 Martocci, "Reactive Discovery of Point-to-Point Routes in 716 Low-Power and Lossy Networks", RFC 6997, August 2013. 718 Appendix A. G.9959 6LoWPAN datagram example 720 This example outlines each individual bit of a sample IPv6 UDP packet 721 arriving to a G.9959 node from a host in the Internet via a PAN 722 border router. 724 In the G.9959 PAN, the complete frame has the following fields. 726 G.9959: 728 +------+---------+----------+---+-----+----------... 729 |HomeID|SrcNodeID|FrmControl|Len|SeqNo|DestNodeID| 730 +------+---------+----------+---+-----+----------+-... 732 6LoWPAN: 734 ...+--------------+----------------+-----------------------... 735 |6LoWPAN CmdCls|6LoWPAN_IPHC Hdr|Compressed IPv6 headers| 736 ...-------------+----------------+-----------------------+-... 738 6LoWPAN, TCP/UDP, App payload: 740 ...+-------------------------+------------+-----------+ 741 |Uncompressed IPv6 headers|TCP/UDP/ICMP|App payload| 742 ...------------------------+------------+-----------+ 744 The frame comes from the source IPv6 address 745 2001:0db8:ac10:ef01::ff:fe00:1206. The source prefix 746 2001:0db8:ac10:ef01/64 is identified by the IPHC CID = 3. 748 The frame is delivered in direct range from the gateway which has 749 source NodeID = 1. The Interface Identifier (IID) ff:fe00:1206 is 750 recognised as a link-layer-derived address and is compressed to the 751 16 bit value 0x1206. 753 The frame is sent to the destination IPv6 address 754 2001:0db8:27ef:42ca::ff:fe00:0004. The destination prefix 755 2001:0db8:27ef:42ca/64 is identified by the IPHC CID = 2. 757 The Interface Identifier (IID) ff:fe00:0004 is recognised as a link- 758 layer-derived address. 760 Thanks to the link-layer-derived addressing rules, the sender knows 761 that this is to be sent to G.9959 NodeID = 4; targeting the IPv6 762 interface instance number 0 (the default). 764 To reach the 6LoWPAN stack of the G.9959 node, (skipping the G.9959 765 header fields) the first octet must be the 6LoWPAN Command Class 766 (0x4F). 768 0 769 0 1 2 3 4 5 6 7 8 770 +-+-+-+-+-+-+-+-... 771 | 0x4F | 772 +-+-+-+-+-+-+-+-+-... 774 The Dispatch header bits '011' advertises a compressed IPv6 header. 776 0 1 777 0 1 2 3 4 5 6 7 8 9 0 778 +-+-+-+-+-+-+-+-+-+-+-... 779 | 0x4F |0 1 1 780 +-+-+-+-+-+-+-+-+-+-+-+-... 782 The following bits encode the first IPv6 header fields: 784 TF = '11' : Traffic Class and Flow Label are elided. 785 NH = '1' : Next Header is elided 786 HLIM = '10' : Hop limit is 64 788 0 1 789 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 791 | 0x4F |0 1 1 1 1 1 1 0| 792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 794 CID = '1' : CI data follows the DAM field 795 SAC = '1' : Src addr uses stateful, context-based compression 796 SAM = '10' : Use src CID and 16 bits for link-layer-derived addr 797 M = '0' : Dest addr is not a multicast addr 798 DAC = '1' : Dest addr uses stateful, context-based compression 799 DAM = '11' : Use dest CID and dest NodeID to link-layer-derived addr 801 0 1 2 802 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 803 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 804 | 0x4F |0 1 1 1 1 1 1 0|1 1 1 0 0 1 1 1| 805 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 807 Address compression context identifiers: 809 SCI = 0x3 810 DCI = 0x2 812 2 3 813 4 5 6 7 8 9 0 1 814 ...+-+-+-+-+-+-+-+-... 815 | 0x3 | 0x2 | 816 ...+-+-+-+-+-+-+-+-... 818 IPv6 header fields: 819 (skipping "version" field) 820 (skipping "Traffic Class") 821 (skipping "flow label") 822 (skipping "payload length") 824 IPv6 header address fields: 826 SrcIP = 0x1206 : Use SCI and 16 LS bits of link-layer-derived address 828 (skipping DestIP ) - completely reconstructed from Dest NodeID and DCI 830 2 3 4 831 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 832 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 833 | 0x3 | 0x2 | 0x12 | 0x06 | 834 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 836 Next header encoding for the UDP header: 838 Dispatch = '11110': Next Header dispatch code for UDP header 839 C = '0' : 16 bit checksum carried inline 840 P = '00' : Both src port and dest Port are carried in-line. 842 4 5 843 8 9 0 1 2 3 4 5 844 ...+-+-+-+-+-+-+-+-... 845 |1 1 1 1 0|0|0 0| 846 ...+-+-+-+-+-+-+-+-... 848 UDP header fields: 850 src Port = 0x1234 851 dest port = 0x5678 853 5 6 7 8 854 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 7 855 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 856 | 0x12 | 0x34 | 0x56 | 0x78 | 857 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.. 859 (skipping "length") 860 checksum = .... (actual checksum value depends on 861 the actual UDP payload) 863 1 864 8 9 0 865 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 866 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 867 | (UDP checksum) | 868 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 870 Add your own UDP payload here... 872 Appendix B. Change Log 874 B.1. Changes since -00 876 o Clarified that mesh-under routing may take place below the 6LoWPAN 877 layer but that specific mesh-under routing protocols are not 878 within the scope of this doc. 880 o Clarified that RFC6282 IPv6 Header Compression MUST be supported. 882 o Clarified the text of section 5.4 on the use of RFC6775 address 883 registration in mesh-under networks. 885 o Split 5.4.2 into multiple paragraphs. 887 B.2. Changes since -01 889 o Added this Change Log 891 o Editorial nits. 893 o Made IPv6 Header Compression mandatory. Therefore, the Dispatch 894 value "01 000001 - Uncompressed IPv6 Addresses" was removed from 895 figure 2. 897 o Changed SHOULD to MUST: An IPv6 host SHOULD construct its link- 898 local IPv6 address and routable IPv6 addresses from the NodeID in 899 order to facilitate IP header compression as described in 900 [RFC6282]. 902 o Changed SHOULD NOT to MUST NOT: Mesh-under networks MUST NOT use 903 [RFC6775] address registration. 905 o Changed SHOULD NOT to MUST NOT: [RFC6775] Duplicate Address 906 Detection (DAD) MUST NOT be used. 908 o Changed SHOULD NOT to MUST NOT: The CID MUST NOT be reused 909 immediately; 911 o Changed SHOULD NOT to MUST NOT: An expired CID and the associated 912 prefix MUST NOT be reset but rather retained in receive-only mode 914 o Changed LBR -> ABR 916 o Changed SHOULD to MUST: , the ABR MUST return an RA with fresh 917 Context Information to the originator. 919 o Changed SHOULD NOT to MUST NOT: This value MUST NOT be used by 920 ABRs. Its use is only intended for a sleeping network controller. 922 B.3. Changes since -02 924 o Editorial nits. 926 o Moved text to the right section so that it does not prohibit DAD 927 for Route-Over deployments. 929 o Introduced RA M flag support so that nodes may be instructed to 930 use DHCPv6 for centralized address assignment. 932 o Added example appendix: Complete G.9959 6LoWPAN datagram 933 composition with CID-based header compression. 935 B.4. Changes since -03 937 o Corrected error in 6LoWPAN datagram example appendix: 64 hop limit 938 in comment => also 64 hop limit in actual frame format. 940 o Added section "Privacy Considerations" 942 B.5. Changes since -04 944 o Text on RA M flag support was replaced with a table to improve 945 clarity. 947 o Added further details to text on achieving privacy addressing with 948 DHCP. 950 B.6. Changes since -05 952 o Term ABR now points to Authoritative 6LBR as defined by RFC6775. 954 o Removed sentence "The G.9959 network controller function SHOULD be 955 integrated in the ABR." as this was an implementation guideline 956 with no relevance to network performance. 958 o Clarifying that network controller function redundancy is relevant 959 for network deployers; not user-level application designers. 961 o Clarified that RFC2460 specifies that link layer must provide 962 fragmentation if 1280 octet packets cannot be carried in one piece 963 by the link layer. 965 o Clarified that the 6LoWPAN CmdCls identifier value is assigned by 966 the ITU-T. 968 o Added reference to Privacy Considerations section from 6LoWPAN 969 Addressing section. 971 o Introducing optional GHC header compression. 973 B.7. Changes since -06 975 o Added a note to section 5, that the mapping of 802.15.4 terms to 976 similar G.9959 terms applies not only to RFC6282 but also to GHC. 978 Authors' Addresses 980 Anders Brandt 981 Sigma Designs 982 Emdrupvej 26A, 1. 983 Copenhagen O 2100 984 Denmark 986 Email: anders_brandt@sigmadesigns.com 988 Jakob Buron 989 Sigma Designs 990 Emdrupvej 26A, 1. 991 Copenhagen O 2100 992 Denmark 994 Email: jakob_buron@sigmadesigns.com