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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: November 6, 2014 May 5, 2014 7 Transmission of IPv6 packets over ITU-T G.9959 Networks 8 draft-ietf-6lo-lowpanz-05 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 November 6, 2014. 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 . . . . . . . . . 4 59 2.1. Addressing mode . . . . . . . . . . . . . . . . . . . . . 4 60 2.2. IPv6 Multicast support . . . . . . . . . . . . . . . . . 5 61 2.3. G.9959 MAC PDU size and IPv6 MTU . . . . . . . . . . . . 6 62 2.4. Transmission status indications . . . . . . . . . . . . . 6 63 2.5. Transmission security . . . . . . . . . . . . . . . . . . 6 64 3. 6LoWPAN Adaptation Layer and Frame Format . . . . . . . . . . 7 65 3.1. Dispatch Header . . . . . . . . . . . . . . . . . . . . . 7 66 4. 6LoWPAN addressing . . . . . . . . . . . . . . . . . . . . . 8 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 . . . . . . . . . . . . . . . . . 9 71 4.4. On the use of Neighbor Discovery technologies . . . . . . 10 72 4.4.1. Prefix and CID management (Route-over) . . . . . . . 10 73 4.4.2. Prefix and CID management (Mesh-under) . . . . . . . 11 74 5. Header Compression . . . . . . . . . . . . . . . . . . . . . 12 75 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 76 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 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 . . . . . . . . . . 15 83 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19 84 B.1. Changes since -00 . . . . . . . . . . . . . . . . . . . . 19 85 B.2. Changes since -01 . . . . . . . . . . . . . . . . . . . . 19 86 B.3. Changes since -02 . . . . . . . . . . . . . . . . . . . . 20 87 B.4. Changes since -03 . . . . . . . . . . . . . . . . . . . . 20 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 90 1. Introduction 92 The ITU-T G.9959 recommendation [G.9959] targets low-power Personal 93 Area Networks (PANs). This document defines the frame format for 94 transmission of IPv6 [RFC2460] packets as well as the formation of 95 IPv6 link-local addresses and statelessly autoconfigured IPv6 96 addresses on G.9959 networks. 98 The general approach is to adapt elements of [RFC4944] to G.9959 99 networks. G.9959 provides a Segmentation and Reassembly (SAR) layer 100 for transmission of datagrams larger than the G.9959 MAC PDU. 102 [RFC6775] updates [RFC4944] by specifying 6LoWPAN optimizations for 103 IPv6 Neighbor Discovery (ND) (originally defined by [RFC4861]). This 104 document limits the use of [RFC6775] to prefix and Context ID 105 assignment. An IID may be constructed from a G.9959 link-layer 106 address, leading to a "link-layer-derived IPv6 address". If using 107 that method, Duplicate Address Detection (DAD) is not needed. 108 Alternatively, IPv6 addresses may be assigned centrally via DHCP, 109 leading to a "non-link-layer-derived IPv6 address". Address 110 registration is only needed in certain cases. 112 In addition to IPv6 application communication, the frame format 113 defined in this document may be used by IPv6 routing protocols such 114 as RPL [RFC6550] or P2P-RPL [RFC6997] to implement IPv6 routing over 115 G.9959 networks. 117 The encapsulation frame defined by this specification may optionally 118 be transported via mesh routing below the 6LoWPAN layer. Mesh-under 119 and route-over routing protocol specifications are out of scope of 120 this document. 122 1.1. Terms used 124 6LoWPAN: IPv6-based Low-power Personal Area Network 126 ABR: Authoritative Border Router ([RFC6775]) 128 Ack: Acknowedgement 130 AES: Advanced Encryption Scheme 132 CID: Context Identifier ([RFC6775]) 134 DAD: Duplicate Address Detection ([RFC6775]) 136 DHCPv6: Dynamic Host Configuration Protocol for IPv6 ([RFC3315]) 138 EUI-64: Extended Unique Identifier ([EUI64]) 140 HomeID: G.9959 Link-Layer Network Identifier 142 IID: Interface IDentifier 144 ITU G.9959: Short range, narrow-band digital radiocommunication 145 transceiver ([G.9959]) 146 Link-layer-derived address: IPv6 Address constructed on basis of link 147 layer address information 149 MAC: Media Access Control 151 Mesh-under: Forwarding via mesh routing below the 6LoWPAN layer 153 MTU: Maximum Transmission Unit 155 ND: Neighbor discovery ([RFC4861], [RFC6775]) 157 NodeID: G.9959 Link-Layer Node Identifier 159 Non-link-layer-derived address: IPv6 Address assigned by a managed 160 process, e.g. DHCPv6. 162 P2P-RPL: Reactive Discovery of Point-to-Point Routes in Low-Power and 163 Lossy Networks ([RFC6997]) 165 PAN: Personal Area Network 167 PDU: Protocol Data Unit 169 RA: Router Advertisement ([RFC4861], [RFC6775]) 171 Route-over: Forwarding via IP routing above the 6LoWPAN layer 173 RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks 174 ([RFC6550]) 176 SAR: G.9959 Segmentation And Reassembly 178 ULA: Unique Local Address [RFC4193] 180 2. G.9959 parameters to use for IPv6 transport 182 This chapter outlines properties applying to the PHY and MAC of 183 G.9959 and how to use these for IPv6 transport. 185 2.1. Addressing mode 187 G.9959 defines how a unique 32-bit HomeID network identifier is 188 assigned by a network controller and how an 8-bit NodeID host 189 identifier is allocated. NodeIDs are unique within the network 190 identified by the HomeID. The G.9959 network controller function 191 SHOULD be integrated in the ABR. The G.9959 HomeID represents an 192 IPv6 subnet which is identified by one or more IPv6 prefixes. 194 An IPv6 host MUST construct its link-local IPv6 address from the 195 link-layer-derived IID in order to facilitate IP header compression 196 as described in [RFC6282]. 198 A node interface MAY support the M flag of the RA message for the 199 construction of routable IPv6 addresses. The M flag MUST be 200 interpreted as defined in Figure 1. 202 +--------+--------+---------------------------------------------+ 203 | M Flag | M flag | Required node behavior | 204 | support| value | | 205 +--------+--------+---------------------------------------------+ 206 | No |(ignore)| Node MUST use link-layer-derived addressing | 207 +--------+--------+---------------------------------------------+ 208 | Yes | 0 | Node MUST use link-layer-derived addressing | 209 | +--------+---------------------------------------------+ 210 | | 1 | Node MUST use DHCPv6 based addressing and | 211 | | | Node MUST comply fully with [RFC6775] | 212 +--------+--------+---------------------------------------------+ 214 Figure 1: RA M flag support and interpretation 216 A node that uses DHCPv6 based addressing MUST comply fully with the 217 text of [RFC6775]. 219 A word of caution: since HomeIDs and NodeIDs are handed out by a 220 network controller function during inclusion, identifier validity and 221 uniqueness is limited by the lifetime of the network membership. 222 This can be cut short by a mishap occurring to the network 223 controller. Having a single point of failure at the network 224 controller suggests that deployers of high-reliability applications 225 should carefully consider adding redundancy to the network controller 226 function. 228 This warning applies to link-layer-derived addressing as well as to 229 non-link-layer-derived addressing deployments. 231 2.2. IPv6 Multicast support 233 [RFC3819] recommends that IP subnetworks support (subnet-wide) 234 multicast. G.9959 supports direct-range IPv6 multicast while subnet- 235 wide multicast is not supported natively by G.9959. Subnet-wide 236 multicast may be provided by an IP routing protocol or a mesh routing 237 protocol operating below the 6LoWPAN layer. Routing protocol 238 specifications are out of scope of this document. 240 IPv6 multicast packets MUST be carried via G.9959 broadcast. 242 As per [G.9959], this is accomplished as follows: 244 1. The destination HomeID of the G.9959 MAC PDU MUST be the HomeID 245 of the network 247 2. The destination NodeID of the G.9959 MAC PDU MUST be the 248 broadcast NodeID (0xff) 250 G.9959 broadcast MAC PDUs are only intercepted by nodes within the 251 network identified by the HomeID. 253 2.3. G.9959 MAC PDU size and IPv6 MTU 255 IPv6 packets MUST be transmitted using G.9959 transmission profile R3 256 or higher. 258 [RFC2460] specifies that IPv6 packets may be up to 1280 octets. 260 G.9959 provides Segmentation And Reassembly for payloads up to 1350 261 octets. IPv6 Header Compression [RFC6282] improves the chances that 262 a short IPv6 packet can fit into a single G.9959 frame. Therefore, 263 section Section 3 specifies that [RFC6282] MUST be supported. With 264 the mandatory link-layer security enabled, a G.9959 R3 MAC PDU may 265 accommodate 6LoWPAN datagrams of up to 130 octets without triggering 266 G.9959 Segmentation and Reassembly (SAR). Longer 6LoWPAN datagrams 267 will lead to the transmission of multiple G.9959 PDUs. 269 2.4. Transmission status indications 271 The G.9959 MAC layer provides native acknowledgement and 272 retransmission of MAC PDUs. The G.9959 SAR layer does the same for 273 larger datagrams. A mesh routing layer may provide a similar feature 274 for routed communication. An IPv6 routing stack communicating over 275 G.9959 may utilize link-layer status indications such as delivery 276 confirmation and Ack timeout from the MAC layer. 278 2.5. Transmission security 280 Implementations claiming conformance with this document MUST enable 281 G.9959 shared network key security. 283 The shared network key is intended to address security requirements 284 in the home at the normal security requirements level. For 285 applications with high or very high requirements on confidentiality 286 and/or integrity, additional application layer security measures for 287 end-to-end authentication and encryption may need to be applied. 288 (The availability of the network relies on the security properties of 289 the network key in any case) 291 3. 6LoWPAN Adaptation Layer and Frame Format 293 The 6LoWPAN encapsulation formats defined in this chapter are carried 294 as payload in the G.9959 MAC PDU. IPv6 header compression [RFC6282] 295 MUST be supported by implementations of this specification. 297 All 6LoWPAN datagrams transported over G.9959 are prefixed by a 298 6LoWPAN encapsulation header stack. The 6LoWPAN payload follows this 299 encapsulation header stack. Each header in the header stack contains 300 a header type followed by zero or more header fields. An IPv6 header 301 stack may contain, in the following order, addressing, hop-by-hop 302 options, routing, fragmentation, destination options, and finally 303 payload [RFC2460]. The 6LoWPAN header format is structured the same 304 way. Currently only one payload option is defined for the G.9959 305 6LoWPAN header format. 307 The definition of 6LoWPAN headers consists of the dispatch value, the 308 definition of the header fields that follow, and their ordering 309 constraints relative to all other headers. Although the header stack 310 structure provides a mechanism to address future demands on the 311 6LoWPAN adaptation layer, it is not intended to provide general 312 purpose extensibility. 314 An example of a complete G.9959 6LoWPAN datagram can be found in 315 Appendix A. 317 3.1. Dispatch Header 319 The dispatch header is shown below: 321 0 1 2 3 322 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 1 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 | 6LoWPAN CmdCls| Dispatch | Type-specific header | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 Figure 2: Dispatch Type and Header 329 6LoWPAN CmdCls: 6LoWPAN Command Class identifier. This field MUST 330 carry the value 0x4F [G.9959]. The value specifies that the 331 following bits are a 6LoWPAN encapsulated datagram. 6LoWPAN protocols 332 MUST ignore the G.9959 frame if the 6LoWPAN Command Class identifier 333 deviates from 0x4F. 335 Dispatch: Identifies the header type immediately following the 336 Dispatch Header. 338 Type-specific header: A header determined by the Dispatch Header. 340 The dispatch value may be treated as an unstructured namespace. Only 341 a few symbols are required to represent current 6LoWPAN 342 functionality. Although some additional savings could be achieved by 343 encoding additional functionality into the dispatch byte, these 344 measures would tend to constrain the ability to address future 345 alternatives. 347 Dispatch values used in this specification are compatible with the 348 dispatch values defined by [RFC4944] and [RFC6282]. 350 +------------+------------------------------------------+-----------+ 351 | Pattern | Header Type | Reference | 352 +------------+------------------------------------------+-----------+ 353 | 01 1xxxxx | 6LoWPAN_IPHC - Compressed IPv6 Addresses | [RFC6282] | 354 +------------+------------------------------------------+-----------+ 355 All other Dispatch values are unassigned in this document. 357 Figure 3: Dispatch values 359 6LoWPAN_IPHC: IPv6 Header Compression. Refer to [RFC6282]. 361 4. 6LoWPAN addressing 363 IPv6 addresses are autoconfigured from IIDs which are again 364 constructed from link-layer address information to save memory in 365 devices and to facilitate efficient IP header compression as per 366 [RFC6282]. 368 A NodeID is mapped into an IEEE EUI-64 identifier as follows: 370 IID = 0000:00ff:fe00:YYXX 372 Figure 4: Constructing a compressible IID 374 where XX carries the G.9959 NodeID and YY is a one byte value chosen 375 by the individual node. The default YY value MUST be zero. A node 376 MAY use other values of YY than zero to form additional IIDs in order 377 to instantiate multiple IPv6 interfaces. The YY value MUST be 378 ignored when computing the corresponding NodeID (the XX value) from 379 an IID. 381 The method of constructing IIDs from the link-layer address obviously 382 does not support addresses assigned or constructed by other means. A 383 node MUST NOT compute the NodeID from the IID if the first 6 bytes of 384 the IID do not comply with the format defined in Figure 4. In that 385 case, the address resolution mechanisms of RFC 6775 apply. 387 4.1. Stateless Address Autoconfiguration of routable IPv6 addresses 389 The IID defined above MUST be used whether autoconfiguring a ULA IPv6 390 address [RFC4193] or a globally routable IPv6 address [RFC3587] in 391 G.9959 subnets. 393 4.2. IPv6 Link Local Address 395 The IPv6 link-local address [RFC4291] for a G.9959 interface is 396 formed by appending the IID defined above to the IPv6 link local 397 prefix FE80::/64. 399 The "Universal/Local" (U/L) bit MUST be set to zero in keeping with 400 the fact that this is not a globally unique value [EUI64]. 402 The resulting link local address is formed as follows: 404 10 bits 54 bits 64 bits 405 +----------+-----------------------+----------------------------+ 406 |1111111010| (zeros) | Interface Identifier (IID) | 407 +----------+-----------------------+----------------------------+ 409 Figure 5: IPv6 Link Local Address 411 4.3. Unicast Address Mapping 413 The address resolution procedure for mapping IPv6 unicast addresses 414 into G.9959 link-layer addresses follows the general description in 415 Section 7.2 of [RFC4861]. The Source/Target Link-layer Address 416 option MUST have the following form when the link layer is G.9959. 418 0 1 419 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | Type | Length=1 | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 | 0x00 | NodeID | 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 | Padding | 426 +- -+ 427 | (All zeros) | 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 Figure 6: IPv6 Unicast Address Mapping 432 Option fields: 434 Type: The value 1 signifies the Source Link-layer address. The value 435 2 signifies the Destination Link-layer address. 437 Length: This is the length of this option (including the type and 438 length fields) in units of 8 octets. The value of this field is 439 always 1 for G.9959 NodeIDs. 441 NodeID: This is the G.9959 NodeID the actual interface currently 442 responds to. The link-layer address may change if the interface 443 joins another network at a later time. 445 4.4. On the use of Neighbor Discovery technologies 447 [RFC4861] specifies how IPv6 nodes may resolve link layer addresses 448 from IPv6 addresses via the use of link-local IPv6 multicast. 449 [RFC6775] is an optimization of [RFC4861], specifically targeting 450 6LoWPAN networks. [RFC6775] defines how a 6LoWPAN node may register 451 IPv6 addresses with an authoritative border router (ABR). Mesh-under 452 networks MUST NOT use [RFC6775] address registration. However, 453 [RFC6775] address registration MUST be used if the first 6 bytes of 454 the IID do not comply with the format defined in Figure 3. 456 4.4.1. Prefix and CID management (Route-over) 458 In route-over environments, IPv6 hosts MUST use [RFC6775] address 459 registration. A node implementation for route-over operation MAY use 460 RFC6775 mechanisms for obtaining IPv6 prefixes and corresponding 461 header compression context information [RFC6282]. RFC6775 Route-over 462 requirements apply with no modifications. 464 4.4.2. Prefix and CID management (Mesh-under) 466 An implementation for mesh-under operation MUST use [RFC6775] 467 mechanisms for managing IPv6 prefixes and corresponding header 468 compression context information [RFC6282]. [RFC6775] Duplicate 469 Address Detection (DAD) MUST NOT be used, since the link-layer 470 inclusion process of G.9959 ensures that a NodeID is unique for a 471 given HomeID. 473 With this exception and the specific redefinition of the RA Router 474 Lifetime value 0xFFFF (refer to Section 4.4.2.3), the text of the 475 following subsections is in compliance with [RFC6775]. 477 4.4.2.1. Prefix assignment considerations 479 As stated by [RFC6775], an ABR is responsible for managing 480 prefix(es). Global routable prefixes may change over time. It is 481 RECOMMENDED that a ULA prefix is assigned to the 6LoWPAN subnet to 482 facilitate stable site-local application associations based on IPv6 483 addresses. A node MAY support the M flag of the RA message. This 484 influences the way IPv6 addresses are assigned. Refer to Section 2.1 485 for details. 487 4.4.2.2. Robust and efficient CID management 489 The 6LoWPAN Context Option (6CO) is used according to [RFC6775] in an 490 RA to disseminate Context IDs (CID) to use for compressing prefixes. 491 One or more prefixes and corresponding Context IDs MUST be assigned 492 during initial node inclusion. 494 When updating context information, a CID may have its lifetime set to 495 zero to obsolete it. The CID MUST NOT be reused immediately; rather 496 the next vacant CID should be assigned. Header compression based on 497 CIDs MUST NOT be used for RA messages carrying Context Information. 498 An expired CID and the associated prefix MUST NOT be reset but rather 499 retained in receive-only mode if there is no other current need for 500 the CID value. This will allow an ABR to detect if a sleeping node 501 without clock uses an expired CID and in response, the ABR MUST 502 return an RA with fresh Context Information to the originator. 504 4.4.2.3. Infinite prefix lifetime support for island-mode networks 506 Nodes MUST renew the prefix and CID according to the lifetime 507 signaled by the ABR. [RFC6775] specifies that the maximum value of 508 the RA Router Lifetime field MAY be up to 0xFFFF. This document 509 further specifies that the value 0xFFFF MUST be interpreted as 510 infinite lifetime. This value MUST NOT be used by ABRs. Its use is 511 only intended for a sleeping network controller; for instance a 512 battery powered remote control being master for a small island-mode 513 network of light modules. 515 5. Header Compression 517 IPv6 header compression [RFC6282] MUST be implemented according to 518 [RFC6282]. This section will simply identify substitutions that 519 should be made when interpreting the text of [RFC6282]. 521 In general the following substitutions should be made: 523 o Replace "802.15.4" with "G.9959" 525 o Replace "802.15.4 short address" with "" 527 o Replace "802.15.4 PAN ID" with "G.9959 HomeID" 529 When a 16-bit address is called for (i.e., an IEEE 802.15.4 "short 530 address") it MUST be formed by prepending an Interface label byte to 531 the G.9959 NodeID: 533 0 1 534 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 536 | Interface | NodeID | 537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 539 A transmitting node may be sending to an IPv6 destination address 540 which can be reconstructed from the link-layer destination address. 541 If the Interface number is zero (the default value), all IPv6 address 542 bytes may be elided. Likewise, the Interface number of a fully 543 elided IPv6 address (i.e. SAM/DAM=11) may be reconstructed to the 544 value zero by a receiving node. 546 64 bit 802.15.4 address details do not apply. 548 6. IANA Considerations 550 This document makes no request of IANA. 552 Note to RFC Editor: this section may be removed on publication as an 553 RFC. 555 7. Security Considerations 557 The method of derivation of Interface Identifiers from 8-bit NodeIDs 558 preserves uniqueness within the network. However, there is no 559 protection from duplication through forgery. Neighbor Discovery in 560 G.9959 links may be susceptible to threats as detailed in [RFC3756]. 561 G.9959 networks may feature mesh routing. This implies additional 562 threats due to ad hoc routing as per [KW03]. G.9959 provides 563 capability for link-layer security. G.9959 nodes MUST use link-layer 564 security with a shared key. Doing so will alleviate the majority of 565 threats stated above. A sizeable portion of G.9959 devices is 566 expected to always communicate within their PAN (i.e., within their 567 subnet, in IPv6 terms). In response to cost and power consumption 568 considerations, these devices will typically implement the minimum 569 set of features necessary. Accordingly, security for such devices 570 may rely on the mechanisms defined at the link layer by G.9959. 571 G.9959 relies on the Advanced Encryption Standard (AES) for 572 authentication and encryption of G.9959 frames and further employs 573 challenge-response handshaking to prevent replay attacks. 575 It is also expected that some G.9959 devices (e.g. billing and/or 576 safety critical products) will implement coordination or integration 577 functions. These may communicate regularly with IPv6 peers outside 578 the subnet. Such IPv6 devices are expected to secure their end-to- 579 end communications with standard security mechanisms (e.g., IPsec, 580 TLS, etc). 582 8. Privacy Considerations 584 IP addresses may be used to track devices on the Internet, which in 585 turn can be linked to individuals and their activities. Depending on 586 the application and the actual use pattern, this may be undesirable. 587 To impede tracking, globally unique and non-changing characteristics 588 of IP addresses should be avoided, e.g. by frequently changing the 589 global prefix and avoiding unique link-layer-derived IIDs in 590 addresses. 592 Some link layers use a 48-bit or a 64-bit link layer address which 593 uniquely identifies the node on a global scale regardless of global 594 prefix changes. The risk of exposing a G.9959 device from its link- 595 layer-derived IID is limited because of the short 8-bit link layer 596 address. 598 While intended for central address management, DHCPv6 address 599 assignment also decouples the IPv6 address from the link layer 600 address. Addresses may be made dynamic by the use of a short DHCP 601 lease period and an assignment policy which makes the DHCP server 602 hand out a fresh IP address every time. 604 It should be noted that privacy and frequently changing address 605 assignment comes at a cost. Non-link-layer-derived IIDs require the 606 use of address registration and further, non-link-layer-derived IIDs 607 cannot be compressed, which leads to longer datagrams and increased 608 link layer segmentation. Finally, frequent prefix changes 609 necessitate more Context Identifier updates, which not only leads to 610 increased traffic but also may affect the battery lifetime of 611 sleeping nodes. 613 9. Acknowledgements 615 Thanks to the authors of RFC 4944 and RFC 6282 and members of the 616 IETF 6LoWPAN working group; this document borrows extensively from 617 their work. Thanks to Erez Ben-Tovim, Erik Nordmark, Kerry Lynn, 618 Michael Richardson, Tommas Jess Christensen for useful comments. 619 Thanks to Carsten Bormann for extensive feedback which improved this 620 document significantly. 622 10. References 624 10.1. Normative References 626 [G.9959] "G.9959 (02/12) + G.9959 Amendment 1 (10/13): Short range, 627 narrow-band digital radiocommunication transceivers", 628 February 2012. 630 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 631 Requirement Levels", BCP 14, RFC 2119, March 1997. 633 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 634 (IPv6) Specification", RFC 2460, December 1998. 636 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 637 Addresses", RFC 4193, October 2005. 639 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 640 Architecture", RFC 4291, February 2006. 642 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 643 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 644 September 2007. 646 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 647 "Transmission of IPv6 Packets over IEEE 802.15.4 648 Networks", RFC 4944, 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 10.2. Informative References 661 [EUI64] IEEE, "GUIIDELINES FOR 64-BIT GLOBAL IDENTIFIER (EUI-64) 662 REGISTRATION AUTHORITY", IEEE Std http:// 663 standards.ieee.org/regauth/oui/tutorials/EUI64.html, 664 November 2012. 666 [KW03] Elsevier's AdHoc Networks Journal, ""Secure Routing in 667 Sensor Networks: Attacks and Countermeasures", Special 668 Issue on Sensor Network Applications and Protocols vol 1, 669 issues 2-3", , September 2003. 671 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 672 and M. Carney, "Dynamic Host Configuration Protocol for 673 IPv6 (DHCPv6)", RFC 3315, July 2003. 675 [RFC3587] Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global 676 Unicast Address Format", RFC 3587, August 2003. 678 [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor 679 Discovery (ND) Trust Models and Threats", RFC 3756, May 680 2004. 682 [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., 683 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 684 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 685 RFC 3819, July 2004. 687 [RFC6550] Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R., 688 Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. 689 Alexander, "RPL: IPv6 Routing Protocol for Low-Power and 690 Lossy Networks", RFC 6550, March 2012. 692 [RFC6997] Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J. 693 Martocci, "Reactive Discovery of Point-to-Point Routes in 694 Low-Power and Lossy Networks", RFC 6997, August 2013. 696 Appendix A. G.9959 6LoWPAN datagram example 698 This example outlines each individual bit of a sample IPv6 UDP packet 699 arriving to a G.9959 node from a host in the Internet via a PAN 700 border router. 702 In the G.9959 PAN, the complete frame has the following fields. 704 G.9959: 706 +------+---------+----------+---+-----+----------... 707 |HomeID|SrcNodeID|FrmControl|Len|SeqNo|DestNodeID| 708 +------+---------+----------+---+-----+----------+-... 710 6LoWPAN: 712 ...+--------------+----------------+-----------------------... 713 |6LoWPAN CmdCls|6LoWPAN_IPHC Hdr|Compressed IPv6 headers| 714 ...-------------+----------------+-----------------------+-... 716 6LoWPAN, TCP/UDP, App payload: 718 ...+-------------------------+------------+-----------+ 719 |Uncompressed IPv6 headers|TCP/UDP/ICMP|App payload| 720 ...------------------------+------------+-----------+ 722 The frame comes from the source IPv6 address 723 2001:0db8:ac10:ef01::ff:fe00:1206. The source prefix 724 2001:0db8:ac10:ef01/64 is identified by the IPHC CID = 3. 726 The frame is delivered in direct range from the gateway which has 727 source NodeID = 1. The Interface Identifier (IID) ff:fe00:1206 is 728 recognised as a link-layer-derived address and is compressed to the 729 16 bit value 0x1206. 731 The frame is sent to the destination IPv6 address 732 2001:0db8:27ef:42ca::ff:fe00:0004. The destination prefix 733 2001:0db8:27ef:42ca/64 is identified by the IPHC CID = 2. 735 The Interface Identifier (IID) ff:fe00:0004 is recognised as a link- 736 layer-derived address. 738 Thanks to the link-layer-derived addressing rules, the sender knows 739 that this is to be sent to G.9959 NodeID = 4; targeting the IPv6 740 interface instance number 0 (the default). 742 To reach the 6LoWPAN stack of the G.9959 node, (skipping the G.9959 743 header fields) the first octet must be the 6LoWPAN Command Class 744 (0x4F). 746 0 747 0 1 2 3 4 5 6 7 8 748 +-+-+-+-+-+-+-+-... 749 | 0x4F | 750 +-+-+-+-+-+-+-+-+-... 752 The Dispatch header bits '011' advertises a compressed IPv6 header. 754 0 1 755 0 1 2 3 4 5 6 7 8 9 0 756 +-+-+-+-+-+-+-+-+-+-+-... 757 | 0x4F |0 1 1 758 +-+-+-+-+-+-+-+-+-+-+-+-... 760 The following bits encode the first IPv6 header fields: 762 TF = '11' : Traffic Class and Flow Label are elided. 763 NH = '1' : Next Header is elided 764 HLIM = '10' : Hop limit is 64 766 0 1 767 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 768 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 769 | 0x4F |0 1 1 1 1 1 1 0| 770 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 772 CID = '1' : CI data follows the DAM field 773 SAC = '1' : Src addr uses stateful, context-based compression 774 SAM = '10' : Use src CID and 16 bits for link-layer-derived addr 775 M = '0' : Dest addr is not a multicast addr 776 DAC = '1' : Dest addr uses stateful, context-based compression 777 DAM = '11' : Use dest CID and dest NodeID to link-layer-derived addr 779 0 1 2 780 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 782 | 0x4F |0 1 1 1 1 1 1 0|1 1 1 0 0 1 1 1| 783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 785 Address compression context identifiers: 787 SCI = 0x3 788 DCI = 0x2 790 2 3 791 4 5 6 7 8 9 0 1 792 ...+-+-+-+-+-+-+-+-... 793 | 0x3 | 0x2 | 794 ...+-+-+-+-+-+-+-+-... 796 IPv6 header fields: 797 (skipping "version" field) 798 (skipping "Traffic Class") 799 (skipping "flow label") 800 (skipping "payload length") 802 IPv6 header address fields: 804 SrcIP = 0x1206 : Use SCI and 16 LS bits of link-layer-derived address 806 (skipping DestIP ) - completely reconstructed from Dest NodeID and DCI 808 2 3 4 809 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 810 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 811 | 0x3 | 0x2 | 0x12 | 0x06 | 812 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 814 Next header encoding for the UDP header: 816 Dispatch = '11110': Next Header dispatch code for UDP header 817 C = '0' : 16 bit checksum carried inline 818 P = '00' : Both src port and dest Port are carried in-line. 820 4 5 821 8 9 0 1 2 3 4 5 822 ...+-+-+-+-+-+-+-+-... 823 |1 1 1 1 0|0|0 0| 824 ...+-+-+-+-+-+-+-+-... 826 UDP header fields: 828 src Port = 0x1234 829 dest port = 0x5678 831 5 6 7 8 832 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 7 833 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 834 | 0x12 | 0x34 | 0x56 | 0x78 | 835 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.. 837 (skipping "length") 838 checksum = .... (actual checksum value depends on 839 the actual UDP payload) 841 1 842 8 9 0 843 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 844 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 845 | (UDP checksum) | 846 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 848 Add your own UDP payload here... 850 Appendix B. Change Log 852 B.1. Changes since -00 854 o Clarified that mesh-under routing may take place below the 6LoWPAN 855 layer but that specific mesh-under routing protocols are not 856 within the scope of this doc. 858 o Clarified that RFC6282 IPv6 Header Compression MUST be supported. 860 o Clarified the text of section 5.4 on the use of RFC6775 address 861 registration in mesh-under networks. 863 o Split 5.4.2 into multiple paragraphs. 865 B.2. Changes since -01 867 o Added this Change Log 869 o Editorial nits. 871 o Made IPv6 Header Compression mandatory. Therefore, the Dispatch 872 value "01 000001 - Uncompressed IPv6 Addresses" was removed from 873 figure 2. 875 o Changed SHOULD to MUST: An IPv6 host SHOULD construct its link- 876 local IPv6 address and routable IPv6 addresses from the NodeID in 877 order to facilitate IP header compression as described in 878 [RFC6282]. 880 o Changed SHOULD NOT to MUST NOT: Mesh-under networks MUST NOT use 881 [RFC6775] address registration. 883 o Changed SHOULD NOT to MUST NOT: [RFC6775] Duplicate Address 884 Detection (DAD) MUST NOT be used. 886 o Changed SHOULD NOT to MUST NOT: The CID MUST NOT be reused 887 immediately; 889 o Changed SHOULD NOT to MUST NOT: An expired CID and the associated 890 prefix MUST NOT be reset but rather retained in receive-only mode 892 o Changed LBR -> ABR 894 o Changed SHOULD to MUST: , the ABR MUST return an RA with fresh 895 Context Information to the originator. 897 o Changed SHOULD NOT to MUST NOT: This value MUST NOT be used by 898 ABRs. Its use is only intended for a sleeping network controller; 900 B.3. Changes since -02 902 o Editorial nits. 904 o Moved text to the right section so that it does not prohibit DAD 905 for Route-Over deployments. 907 o Introduced RA m flag support so that nodes may be instructed to 908 use DHCPv6 for centralized address assignment. 910 o Added example appendix: Complete G.9959 6LoWPAN datagram 911 composition with CID-based header compression 913 B.4. Changes since -03 915 o Corrected error in 6LoWPAN datagram example appendix: 64 hop limit 916 in comment => also 64 hop limit in actual frame format. 918 o Added section "Privacy Considerations" 920 Authors' Addresses 922 Anders Brandt 923 Sigma Designs 924 Emdrupvej 26A, 1. 925 Copenhagen O 2100 926 Denmark 928 Email: anders_brandt@sigmadesigns.com 930 Jakob Buron 931 Sigma Designs 932 Emdrupvej 26A, 1. 933 Copenhagen O 2100 934 Denmark 936 Email: jakob_buron@sigmadesigns.com