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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-23) exists of draft-ietf-6lo-ap-nd-12 == Outdated reference: A later version (-18) exists of draft-ietf-roll-efficient-npdao-15 == Outdated reference: A later version (-44) exists of draft-ietf-roll-useofrplinfo-31 ** Downref: Normative reference to an Informational RFC: RFC 4919 ** Downref: Normative reference to an Informational RFC: RFC 6606 -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ROLL P. Thubert, Ed. 3 Internet-Draft Cisco 4 Updates: 6550, 8505 (if approved) M. Richardson 5 Intended status: Standards Track Sandelman 6 Expires: March 2, 2020 August 30, 2019 8 Routing for RPL Leaves 9 draft-ietf-roll-unaware-leaves-03 11 Abstract 13 This specification extends RFC6550 and RFC8505 to provide unicast and 14 multicast routing services in a RPL domain to 6LNs that are plain 15 hosts and do not participate to RPL. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at https://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on March 2, 2020. 34 Copyright Notice 36 Copyright (c) 2019 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (https://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 53 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4 55 2.3. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 56 3. 6LoWPAN Neighbor Discovery . . . . . . . . . . . . . . . . . 6 57 4. Updating RFC 6550 . . . . . . . . . . . . . . . . . . . . . . 8 58 5. Updating RFC 8505 . . . . . . . . . . . . . . . . . . . . . . 9 59 6. 6LN Requirements to be a RPL-Unware Leaf . . . . . . . . . . 9 60 6.1. Support of 6LoWPAN ND . . . . . . . . . . . . . . . . . . 9 61 6.2. External Routes and RPL Artifacts . . . . . . . . . . . . 10 62 6.2.1. Support of the HbH Header . . . . . . . . . . . . . . 10 63 6.2.2. Support of the Routing Header . . . . . . . . . . . . 10 64 6.2.3. Support of IPv6 Encapsulation . . . . . . . . . . . . 11 65 7. Updated RPL Target option . . . . . . . . . . . . . . . . . . 11 66 8. Protocol Operations for Unicast Addresses . . . . . . . . . . 12 67 8.1. General Flow . . . . . . . . . . . . . . . . . . . . . . 12 68 8.1.1. In RPL Non-Storing-Mode . . . . . . . . . . . . . . . 12 69 8.1.2. In RPL Storing-Mode . . . . . . . . . . . . . . . . . 14 70 8.2. Operation . . . . . . . . . . . . . . . . . . . . . . . . 15 71 8.2.1. By the 6LN . . . . . . . . . . . . . . . . . . . . . 15 72 8.2.2. By the 6LR . . . . . . . . . . . . . . . . . . . . . 16 73 8.2.3. By the RPL Root . . . . . . . . . . . . . . . . . . . 18 74 8.2.4. By the 6LBR . . . . . . . . . . . . . . . . . . . . . 19 75 9. Protocol Operations for Multicast Addresses . . . . . . . . . 20 76 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 22 77 11. Security Considerations . . . . . . . . . . . . . . . . . . . 22 78 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 79 12.1. RPL Target Option Flags . . . . . . . . . . . . . . . . 22 80 12.2. New Subsubregistry for the Status values of the RPL DAO- 81 ACK Message . . . . . . . . . . . . . . . . . . . . . . 22 82 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 83 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 84 14.1. Normative References . . . . . . . . . . . . . . . . . . 23 85 14.2. Informative References . . . . . . . . . . . . . . . . . 25 86 Appendix A. Example Compression . . . . . . . . . . . . . . . . 26 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 89 1. Introduction 91 The design of Low Power and Lossy Networks (LLNs) is generally 92 focused on saving energy, which is the most constrained resource of 93 all. Other design constraints, such as a limited memory capacity, 94 duty cycling of the LLN devices and low-power lossy transmissions, 95 derive from that primary concern. 97 The IETF produced the "Routing Protocol for Low Power and Lossy 98 Networks" [RFC6550] (RPL) to provide IPv6 [RFC8200] routing services 99 within such constraints. RPL is a Distance-Vector protocol, which, 100 compared to link-state protocols, limits the amount of topological 101 knowledge that needs to be installed and maintained in each node. In 102 order to operate in constrained networks, RPL allows a Routing 103 Stretch (see [RFC6687]), whereby routing is only performed along a 104 DODAG as opposed to straight along a shortest path between 2 peers, 105 whatever that would mean in a given LLN. This trades the quality of 106 peer-to-peer (P2P) paths for a vastly reduced amount of control 107 traffic and routing state that would be required to operate a any-to- 108 any shortest path protocol. Finally, broken routes may be fixed 109 lazily and on-demand, based on dataplane inconsistency discovery, 110 which avoids wasting energy in the proactive repair of unused paths. 112 In order to cope with lossy transmissions, RPL forms Direction- 113 Oriented Directed Acyclic Graphs (DODAGs) using DODAG Information 114 Solicitation (DIS) and DODAG Information Object (DIO) messages. For 115 most of the nodes, though not all, a DODAG provides multiple 116 forwarding solutions towards the Root of the topology via so-called 117 parents. RPL is designed to adapt to fuzzy connectivity, whereby the 118 physical topology cannot be expected to reach a stable state, with a 119 lazy control that creates routes proactively but only fixes them when 120 they are used by actual traffic. The result is that RPL provides 121 reachability for most of the LLN nodes, most of the time, but may not 122 really converge in the classical sense. RPL provides unicast and 123 multicast routing services back to RPL-Aware nodes (RANs). A RAN 124 will inject routes to itself using Destination Advertisement Object 125 (DAO) messages sent to either parent-nodes in Storing Mode or to the 126 Root indicating their parent in Non-Storing Mode. This process 127 effectively forms a DODAG back to the device that is a subset of the 128 DODAG to the Root with all links reversed. 130 When a routing protocol such as RPL is used to maintain reachability 131 within a Non-Broadcast Multi-Access (NBMA) subnet, some nodes may act 132 as routers and participate to the routing operations whereas others 133 may be plain hosts. In [RFC6550] terms, a host that is reachable 134 over the RPL network is called a Leaf. 136 "When to use RFC 6553, 6554 and IPv6-in-IPv6" 137 [I-D.ietf-roll-useofrplinfo] introduces the term RPL-Aware-Leaf (RAL) 138 for a leaf that injects routes in RPL to manage the reachability of 139 its own IPv6 addresses. In contrast, a RPL-Unaware Leaf (RUL) 140 designates a leaf does not participate to RPL at all. In that case, 141 the 6LN is a plain host that needs an interface to its RPL router to 142 obtain routing services over the LLN. This specification enables a 143 RPL-Unaware Leaf (RUL) to announce itself as a host and request that 144 6LRs that accept the registration also inject the relevant routing 145 information for the Registered Address in the RPL domain on its 146 behalf. The unicast packet forwarding operation by the 6LR serving a 147 Leaf 6LN is described in [I-D.ietf-roll-useofrplinfo]. 149 Examples of routing-agnostic 6LN may include lightly-powered sensors 150 such as window smash sensor (alarm system), or the kinetically 151 powered light switch. Other application of this specification may 152 include a smart grid network that controls appliances - such as 153 washing machines or the heating system - in the home. Applicances 154 may not participate to the RPL protocol operated in the smart grid 155 network but can still receive control packet from the smart grid. 157 2. Terminology 159 2.1. BCP 14 161 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 162 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 163 "OPTIONAL" in this document are to be interpreted as described in BCP 164 14 [RFC2119][RFC8174] when, and only when, they appear in all 165 capitals, as shown here. 167 2.2. References 169 The Terminology used in this document is consistent with and 170 incorporates that described in Terms Used in Routing for Low-Power 171 and Lossy Networks (LLNs). [RFC7102]. 173 A glossary of classical 6LoWPAN acronyms is given in Section 2.3. 175 The term "byte" is used in its now customary sense as a synonym for 176 "octet". 178 "RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by 179 a RPLInstanceID)are defined in "RPL: IPv6 Routing Protocol for Low- 180 Power and Lossy Networks" [RFC6550] . The DODAG Information 181 Solicitation (DIS), Destination Advertisement Object (DAO) and DODAG 182 Information Object (DIO) messages are also specified in [RFC6550]. 183 The Destination Cleanup Object (DCO) message is defined in 184 [I-D.ietf-roll-efficient-npdao]. 186 This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware 187 Leaf (RAL) consistently with [I-D.ietf-roll-useofrplinfo]. The term 188 RPL-Aware Node (RAN) is introduced to refer to a node that is either 189 a RAL or a RPL router. As opposed to a RUL, a RAN manages the 190 reachability of its addresses and prefixes by injecting them in RPL 191 by itself. 193 Other terms in use in LLNs are found in Terminology for Constrained- 194 Node Networks [RFC7228]. 196 Readers are expected to be familiar with all the terms and concepts 197 that are discussed in 199 o "Neighbor Discovery for IP version 6" [RFC4861], 201 o "IPv6 Stateless Address Autoconfiguration" [RFC4862], 203 o "Problem Statement and Requirements for IPv6 over Low-Power 204 Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606], 206 o "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): 207 Overview, Assumptions, Problem Statement, and Goals" [RFC4919], 209 o "Neighbor Discovery Optimization for Low-power and Lossy Networks" 210 [RFC6775], and 212 o "Registration Extensions for IPv6 over Low-Power Wireless Personal 213 Area Network (6LoWPAN) Neighbor Discovery" [RFC8505]. 215 2.3. Glossary 217 This document often uses the following acronyms: 219 AR: Address Resolution (aka Address Lookup) 221 6LBR: 6LoWPAN Border Router 223 6LN: 6LoWPAN Node (a Low Power host or router) 225 6LR: 6LoWPAN Router 227 6CIO: Capability Indication Option 229 (E)ARO: (Extended) Address Registration Option 231 (E)DAR: (Extended) Duplicate Address Request 233 (E)DAC: (Extended) Duplicate Address Confirmation 235 DAD: Duplicate Address Detection 237 DAO: Destination Advertisement Object 239 DCO: Destination Cleanup Object 240 DIS: DODAG Information Solicitation 242 DIO: DODAG Information Object 244 DODAG: Destination-Oriented Directed Acyclic Graph 246 LLN: Low-Power and Lossy Network 248 NA: Neighbor Advertisement 250 NCE: Neighbor Cache Entry 252 ND: Neighbor Discovery 254 NDP: Neighbor Discovery Protocol 256 NS: Neighbor Solicitation 258 RA: Router Advertisement 260 ROVR: Registration Ownership Verifier 262 RPI: RPL Packet Information (an Option in the Hop-By_Hop Header) 264 RAL: RPL-Aware Leaf 266 RAN: RPL-Aware Node (either a RPL router or a RPL-Aware Leaf) 268 RUL: RPL-Unaware Leaf 270 TID: Transaction ID (a sequence counter in the EARO) 272 3. 6LoWPAN Neighbor Discovery 274 The "IPv6 Neighbor Discovery (IPv6 ND) Protocol" (NDP) suite 275 [RFC4861] [RFC4862] was defined for transit media such a Ethernet, 276 and relies heavily on multicast operations for address discovery and 277 duplicate address detection (DAD). 279 "Neighbor Discovery Optimizations for 6LoWPAN networks" [RFC6775] 280 (6LoWPAN ND) adapts IPv6 ND for operations over energy-constrained 281 LLNs. In particular, 6LoWPAN ND introduces a unicast host address 282 registration mechanism that contributes to reducing the use of 283 multicast messages that are present in the classical IPv6 ND 284 protocol. 6LoWPAN ND defines a new Address Registration Option (ARO) 285 that is carried in the unicast Neighbor Solicitation (NS) and 286 Neighbor Advertisement (NA) messages between the 6LoWPAN Node (6LN) 287 and the 6LoWPAN Router (6LR). 6LoWPAN ND also defines the Duplicate 288 Address Request (DAR) and Duplicate Address Confirmation (DAC) 289 messages between the 6LR and the 6LoWPAN Border Router (6LBR). In an 290 LLN, the 6LBR is the central repository of all the Registered 291 Addresses in its domain. 293 "Registration Extensions for 6LoWPAN Neighbor Discovery" [RFC8505] 294 updates the behavior of RFC 6775 to enable a generic registration to 295 routing services and defines an Extended ARO (EARO). The format of 296 the EARO is shown in Figure 1: 298 0 1 2 3 299 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 1 300 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 301 | Type | Length | Status | Opaque | 302 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 303 | Rsvd | I |R|T| TID | Registration Lifetime | 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 | | 306 ... Registration Ownership Verifier ... 307 | | 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 310 Figure 1: EARO Option Format 312 [RFC8505] specifies the use of the R flag in the EARO by the 313 Registering Node. With [RFC8505], the Registering Node sets the R 314 flag to indicate whether the 6LR should ensure reachability for the 315 Registered Address, e.g., by means of routing or proxying ND. 316 Adapted to this specification, this means that a 6LN operates as a 317 RUL for an IPv6 address iff it sets the R flag in the NS(EARO) used 318 to register the address. If the R flag is not set, then the 319 Registering Node is expected to be a RAN that handles the 320 reachability of the Registered Address by itself. Conversely, this 321 document specifies a behavior of a RPL router acting as 6LR for the 322 registration 6LR that depends on the setting of the R flag in the 323 NS(EARO). The RPL router generates a DAO message for the Registered 324 Address upon an NS(EARO) iff the R flag in the EARO is set. 326 The EARO also includes a sequence counter called Transaction ID 327 (TID), which maps to the Path Sequence Field found in Transit Options 328 in RPL DAO messages. This is the reason why the support of [RFC8505] 329 by the RUL as opposed to only [RFC6775] is a prerequisite for this 330 specification (more in Section 6.1). The EARO also transports an 331 Opaque field and an "I" field that describes what the Opaque field 332 transports and how to use it. 334 Section 8.2.1 specifies the use of the R flag, of the "I" field and 335 of the Opaque field by a RUL. 337 "Address Protected Neighbor Discovery for Low-power and Lossy 338 Networks" [I-D.ietf-6lo-ap-nd] protects the ownership of an address 339 and enables a challenge that is leveraged by this specification. It 340 also enables Source Address Validation by a 6LR that will drop the 341 packets that are sourced at an address that is not registered. 343 4. Updating RFC 6550 345 This document specifies a new behavior whereby a 6LR injects DAO 346 messages for unicast addresses (see Section 8) and multicast 347 addresses (see Section 9) on behalf of leaves that are not aware of 348 RPL. The Targets are exposed as External addresses. An IP-in-IP 349 encapsulation that terminates at the border 6LR is used to remove RPL 350 artifacts and compression techniques that may not be processed 351 correctly outside of the RPL domain. This specification updates RPL 352 [RFC6550] to mandate that External Routes are advertised using Non- 353 Storing Mode signaling even in a Storing-Mode network in order to 354 inform the root of the address of the 6LR that terminates the IP-in- 355 IP tunnel. 357 [RFC8505] specifies a periodic EDAR/EDAC exchange that takes place 358 between the 6LR and the 6LBR. It is triggered by a NS(EARO) message 359 and is intended to create and then refresh the corresponding state in 360 the 6LBR for a lifetime that is indicated by the 6LN. Conversely, 361 RPL [RFC6550] specifies a periodic DAO that maintains the routing 362 state in the RPL network for a lifetime that is indicated by the 363 source of the DAO. This means that there are two periodic messages 364 that traverse the whole network to indicate that an address is still 365 reachable, one to the Root and one to the 6LBR. 367 This document synchronizes the liveness monitoring at the Root and 368 the 6LBR. A same value of lifetime is used for both, and a single 369 keep alive message, the RPL DAO, traverses the RPL network. A new 370 behavior is introduced whereby the RPL Root proxies the EDAR message 371 to the 6LBR on behalf of the 6LR (more in Section 5). [RFC6550] is 372 updated with new RPL Status values for use in DAO-ACK and DCO that 373 map the 6LoWNAN ND values defined in Table 1 of [RFC8505]. The 374 Resulting set is shown in Table 1. The Status code are listed in the 375 same order and DAO-ACK Status code of 128 maps to 6LoWPAN ND Status 376 Code of 1. 378 Section 5.3. of [RFC8505] introduces the Registration Ownership 379 Verifier (ROVR) of a variable length from 64 to 256 bits. A ROVR is 380 created by the Registering Node and associated to the registration of 381 an IPv6 Address. It is used to detect a duplication (DAD) and may 382 also enable the Registering Node to prove its ownership of the 383 Registered Address [I-D.ietf-6lo-ap-nd]. Section 6.7. of [RFC6550] 384 introduces the RPL Control Message Options such as the RPL Target 385 Option that can be included in a RPL Control Message such as the DAO. 386 This document updates the RPL Target Option to optionally transport a 387 ROVR, more in Section 7. This enables the RPL Root to generate a 388 full EDAR Message as opposed to a keep-alive EDAR that has restricted 389 properties. 391 5. Updating RFC 8505 393 This document updates [RFC8505] to introduce a keep-alive EDAR 394 message and a keep-alive NS(EARO) message. The keep-alive messages 395 are used for backward compatibility, when the DAO does not transport 396 a ROVR as specified in Section 7. The keep-alive messages have a 397 zero ROVR field and can only be used to refresh a pre-existing state 398 associated to the Registered Address. More specifically, a keep- 399 alive message can only increase the lifetime and/or increment the TID 400 of the existing state in a 6LBR. 402 Upon the renewal of a 6LoWPAN ND registration, this specification 403 changes the behavior of a RPL router acting as 6LR for the 404 registration as follows: if the Root indicates the capability to 405 proxy the EDAR/EDAC exchange to the 6LBR then the 6LR refrains from 406 sending an EDAR message. If the Root is separated from the 6LBR, the 407 Root regenerates the EDAR message to the 6LBR upon a DAO message that 408 signals the liveliness of the Address. 410 6. 6LN Requirements to be a RPL-Unware Leaf 412 This document provides RPL routing for a RUL, that is a 6LN acting as 413 a plain host and not aware of RPL. Still, a minimal RPL-independent 414 functionality is expected from the 6LN in order to obtain routing 415 services from the 6LR. 417 6.1. Support of 6LoWPAN ND 419 A RUL MUST implement [RFC8505] and set the R flag in the EARO option. 420 A 6LN is considered to be a RUL if and only if it sets the R flag in 421 the EARO. 423 A RUL SHOULD implement [RFC8505] and set the R flag in the EARO 424 option. A 6LN is considered to be a RUL if and only if it sets the R 425 flag in the EARO. 427 [RFC8505] introduces error Status values in the NA(EARO) which can be 428 received synchronously upon an NS(EARO) or asynchronously. The RUL 429 MUST support both cases and refrain from using the Registered Address 430 as suggested by [RFC8505] depending on the Status value. 432 A RUL SHOULD supports [I-D.ietf-6lo-ap-nd] to protect the ownership 433 of its addresses. 435 6.2. External Routes and RPL Artifacts 437 RPL data packets are often encapsulated using IP-in-IP and in Non- 438 Storing Mode, packets going down will carry an SRH as well. RPL data 439 packets also typically carry a Hop-by-Hop Header to transport a RPL 440 Packet Information (RPI) [RFC6550]. These additional headers are 441 called RPL artifacts. When IP-in-IP is used and the outer headers 442 terminate at a 6LR down the path (see Figure 8 for the format in 443 Storing Mode), then the 6LR decapsulates the IP-in-IP and the packet 444 that is forwarded to the external destination is free of RPL 445 artifacts. 447 IP-in-IP to the 6LR MUST be used if the final destination cannot 448 handle or ignore the RPL artifacts or the way they are compressed 449 [RFC8138]. An External route indicates by default a node or a prefix 450 that is not known to handle or ignore the RPL artifacts. The 451 RECOMMENDED behaviour when using IP-in-IP to an External route is 452 that the outer headers terminate at the 6LR that injected the 453 External route. Non-Storing Mode signaling MUST be used to inject 454 External routes to the Root in order to advertise the 6LR that is 455 associated to a RUL. 457 In order to save the IP-in-IP encapsulation and to support Storing 458 Mode of operation, it is preferred that the 6LN can ignore an RPI and 459 consume a routing header in both the native and [RFC8138]-compressed 460 forms. In order to enable IP-in-IP to a 6LN in Non-Storing Mode, it 461 is also of interest that the 6LN supports decapsulating IP-in-IP in 462 both forms. 464 6.2.1. Support of the HbH Header 466 A RUL is expected to process an unknown Option Type in a Hop-by-Hop 467 Header as prescribed by section 4.2 of [RFC8200]. This means in 468 particular that an RPI with an Option Type of 0x23 469 [I-D.ietf-roll-useofrplinfo] is ignored when not understood. 471 6.2.2. Support of the Routing Header 473 A RUL is expected to process an unknown Routing Header Type as 474 prescribed by section 4.4 of [RFC8200]. This means in particular 475 that Routing Header with a Routing Type of 3 [RFC6553] is ignored 476 when the Segments Left is zero, and dropped otherwise. 478 6.2.3. Support of IPv6 Encapsulation 480 A RUL may support IPv6-in-IPv6 decapsulation when it is the 481 destination of the outer header but that is not assumed by [RFC8504]. 482 If the 6LN is a RUL, it may be able to drop the inner packet if it is 483 not the destination of the inner header. By default the IP-in-IP 484 tunnel should terminate at the parent 6LR so supporting this 485 capability in a RUL is secondary. 487 7. Updated RPL Target option 489 This specification updates the RPL Target option to transport the 490 ROVR as illustrated in Figure 2. The Target Prefix MUST be aligned 491 to the next 4-byte boundary after the size indicated by the Prefix 492 Length. if necessary it is padded with zeros. The size of the ROVR 493 is indicated in a new ROVR Type field that is encoded to map the 494 CodePfx in the EDAR message (see section 4.2 of [RFC8505]). With 495 this specification the ROVR is the remainder of the RPL Target 496 Option. 498 0 1 2 3 499 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 1 500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 501 | Type = 0x05 | Option Length |ROVRsz | Flags | Prefix Length | 502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 | | 504 + + 505 | Target Prefix (Variable Length) | 506 . Aligned to 4-byte boundary . 507 . . 508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 509 | | 510 ... Registration Ownership Verifier (ROVR) ... 511 | | 512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 514 Figure 2: Updated Target Option 516 New fields: 518 RVRsz: Indicates the Size of the ROVR. It MAY be 1, 2, 3, 519 or 4, denoting a ROVR size of 64, 128, 192, or 256 520 bits, respectively. 522 Registration Ownership Verifier (ROVR): This is the same field as in 523 the EARO, see [RFC8505] 525 8. Protocol Operations for Unicast Addresses 527 8.1. General Flow 529 This specification enables to save the exchange of Extended Duplicate 530 Address messages, EDAR and EDAC, from a 6LN all the way to the 6LBR 531 across a RPL mesh, for the sole purpose of refreshing an existing 532 state in the 6LBR. Instead, the EDAR/EDAC exchange is proxied by the 533 RPL Root upon a DAO message that refreshes the RPL routing state. To 534 achieve this, the lifetimes and sequence counters in 6LoWPAN ND and 535 RPL are aligned. In other words, the Path Sequence and the Path 536 Lifetime in the DAO message are taken from the Transaction ID and the 537 registration lifetime in the NS(EARO) message from the 6LN. 539 In that flow, the RPL Root acts as a proxy to refresh the state in 540 the 6LBR. The proxy operation applies to both RUL and RAN. This 541 means that in a RPL network where the function is enabled, refreshing 542 the state in the 6LBR is the responsibility of the Root. 543 Consequently, only addresses that are injected in RPL will be kept 544 alive by the RPL Root. If an additional routing protocol is deployed 545 on a same network, that additional routing protocol may need to 546 handle the keep alive procedure for the addresses that it serves. 548 From the perspective of the 6LN, the registration flow happens 549 transparently; it is not delayed by the proxy RPL operation, so the 550 device does not need to change the amount of time it waits based upon 551 whether RPL proxy operation happens or not. 553 On the first registration, illustrated in Figure 3, from the 554 perspective of the 6LR in Non-Storing Mode, the Extended Duplicate 555 Address message takes place as prescribed by [RFC8505]. When 556 successful, the flow creates a Neighbor Cache Entry (NCE) in the 6LR, 557 and the 6LR injects the Registered Address in RPL using DAO/DAO-ACK 558 exchanges all the way to the RPL DODAG Root. The protocol does not 559 carry a specific information that the Extended Duplicate Address 560 messages were already exchanged, so the Root proxies them anyway. 562 Note that any of the functions 6LR, Root and 6LBR might be collapsed 563 in a single node, in which case the flow above happens internally, 564 and possibly through internal API calls as opposed to messaging. 566 8.1.1. In RPL Non-Storing-Mode 568 In Non-Storing Mode, the flows can be nested as illustrated in 569 Figure 3 and it is possible to carry information such as an updated 570 lifetime from the 6LBR all the way to the 6LN. 572 6LN 6LR Root 6LBR 573 | | | | 574 | NS(EARO) | | | 575 |--------------->| | 576 | | Extended DAR | 577 | |-------------------------------->| 578 | | | 579 | | Extended DAC | 580 | |<--------------------------------| 581 | | DAO | | 582 | |-------------->| | 583 | | | keep-alive EDAR | 584 | | |---------------->| 585 | | | EDAC | 586 | | |<----------------| 587 | | DAO-ACK | | 588 | |<--------------| | 589 | NA(EARO) | | 590 |<---------------| | | 591 | | | | 592 (in case if an Error not reported in DAO-ACK) 593 | | | | 594 | | DCO | | 595 | |<--------------| | 596 | NA(EARO) | | | 597 |<---------------| | | 598 | | | | 600 Figure 3: First Registration Flow in Non-Storing Mode 602 A re-registration is performed by the 6LN to maintain the NCE in the 603 6LR alive before lifetime expires. Upon a re-registration, as 604 illustrated in Figure 4, the 6LR redistributes the Registered Address 605 NS(EARO) in RPL. 607 This causes the RPL DODAG Root to refresh the state in the 6LBR with 608 a keep-alive EDAC message. The keep-alive EDAC lacks the 609 Registration Ownership Verifier (ROVR) information, since it is not 610 present in RPL DAO messages, but the EDAC message sent in response by 611 the 6LBR contains the actual value of the ROVR field for that 612 registration. This enables the RPL Root to perform the proxy- 613 registration for the Registered Address and attract traffic captured 614 over the backbone by the 6BBR and route it back to the device. 616 6LN 6LR Root 6LBR 617 | | | | 618 | NS(EARO) | | | 619 |--------------->| | 620 | | DAO | | 621 | |-------------->| | 622 | | | keep-alive EDAR | 623 | | |---------------->| 624 | | | EDAC | 625 | | |<----------------| 626 | | DAO-ACK | | 627 | |<--------------| | 628 | NA(EARO) | | 629 |<---------------| | | 630 | | | | 632 Figure 4: Next Registration Flow in Non-Storing Mode 634 In case of an error on the keep-alive EDAR flow, the error SHOULD be 635 returned in the DAO-ACK - if one was requested - using the mapping of 636 RPL Status and 6LoWPAN Status values discussed in Section 4. 638 If the Root could not return the negative Status in the DAO-ACK then 639 it sends an asynchronous Destination Cleanup Object (DCO) message 640 [I-D.ietf-roll-efficient-npdao] to the 6LR indicating the issue with 641 the mapped Status value. Note that if both are used in a short 642 interval of time, the DAO-ACK and DCO messages are not guaranteed to 643 arrive in the same order at the 6LR. So the 6LR must still expect a 644 DAO-ACK even if it received a DCO while it was waiting for an 645 acknowledgement for a short period of time, but the negative status 646 in the DCO supercedes a positive status in the DAO-ACK regardless of 647 the order in which they are received. 649 Upon the DAO-ACK - or the DCO if it arrives first - the 6LR responds 650 to the RUL with a NA(EARO) and the 6LoWPAN ND Status value that is 651 mapped from the RPL status in the RPL message. An asynchronous DCO 652 is also mapped in an asynchronous NA(EARO) to the RUL with a mapped 653 Status value. 655 8.1.2. In RPL Storing-Mode 657 In Storing Mode, the DAO-ACK is optional. When it is used, it is 658 generated by the RPL parent, which does not need to wait for the 659 grand-parent to send the acknowledgement. A successful DAO-ACK is 660 not a guarantee that the DAO has yet reached the Root or that the 661 keep-alive EDAR has succeeded. 663 If the keep alive fails, the path is cleaned up asynchronously using 664 a DCO message [I-D.ietf-roll-efficient-npdao] as illustrated in 665 Figure 5 and described in further details in Section 8.2.3. 667 6LN 6LR 6LR Root 6BBR 668 | | | | | 669 | NS(EARO) | | | | 670 |-------------->| | | | 671 | NA(EARO) | | | | 672 |<--------------| | | | 673 | | | | | 674 | | DAO | | | 675 | |-------------->| | | 676 | | DAO-ACK | | | 677 | |<--------------| | | 678 | | | | | 679 | | | DAO | | 680 | | |-------------->| | 681 | | | DAO-ACK | | 682 | | |<--------------| | 683 | | | | | 684 | | | | keep-alive EDAR | 685 | | | |---------------->| 686 | | | | EDAC(ROVR) | 687 | | | |<----------------| 688 | | | | | 689 (in case if an Error) 690 | | | | | 691 | | DCO | | 692 | |<------------------------------| | 693 | NA(EARO) | | | | 694 |<--------------| | | | 695 | | | | | 697 Figure 5: Next Registration Flow in Storing Mode 699 8.2. Operation 701 8.2.1. By the 6LN 703 This specification does not alter the operation of a 6LoWPAN ND- 704 compliant 6LN, and a RUL is expected to operate as follows: 706 o The 6LN obtains an IPv6 global address, for instance using 707 autoconfiguration [RFC4862] based on a Prefix Information Option 708 (PIO) [RFC4861] found in a Router Advertisement message or by some 709 other means such as DHCPv6 [RFC3315]. 711 o Once it has formed an address, the 6LN (re)registers its address 712 periodically, within the Lifetime of the previous registration, as 713 prescribed by [RFC6775]. 715 o A 6LN acting as a RUL sets the R flag in the EARO whereas a 6LN 716 acting as a RAN does not set the R flag as prescribed by [RFC8505] 717 section 5.1. 719 o Upon each consecutive registration, the 6LN increases the TID 720 field in the EARO, as prescribed by [RFC8505] section 5.2. 722 o The 6LN can register to more than one 6LR at the same time. In 723 that case, a same value of TID is used for each registration. 725 o The 6LN may use any of the 6LRs to which it register to forward 726 its packets. Using a 6LR to which the 6LN is not registered may 727 result in packets dropped by a Source Address Validation function. 729 Even without support for RPL, a RUL may be aware of opaque values to 730 be provided to the routing protocol. If the RUL has a knowledge of 731 the RPL Instance the packet should be injected into, then it SHOULD 732 set the Opaque field in the EARO to the RPLInstanceID, else it MUST 733 leave the Opaque field to zero. In any fashion the 6LN MUST set the 734 "I" field to zero to indicate that topological information to be 735 passed to a routing process as specified in [RFC8505] section 5.1. 737 A RUL is not expected to produce RPL artifacts in the data packets, 738 but it MAY do so. for instance, if the RUL has a minimal awareness of 739 the RPL Instance and can build an RPI. A RUL that places an RPI in a 740 data packet MUST indicate the RPLInstanceID that corresponds to the 741 RPL Instance the packet should be injected into. All the flags and 742 the Rank field are set to zero as specified by section 11.2 of 743 [RFC6550]. 745 8.2.2. By the 6LR 747 Also as prescribed by [RFC8505], the 6LR generates a DAR message upon 748 reception of a valid NS(EARO) message for the registration of a new 749 IPv6 Address by a 6LN. If the Duplicate Address exchange succeeds, 750 then the 6LR installs a Neighbor Cache Entry (NCE). If the R flag 751 was set in the EARO of the NS message, and this 6LR can manage the 752 reachability of Registered Address, then the 6LR sets the R flag in 753 the EARO of the NA message that is sent in response. 755 From then on, the 6LN periodically sends a new NS(EARO) to refresh 756 the NCE state before the lifetime indicated in the EARO expires, with 757 TID that is incremented each time till it wraps in a lollipop fashion 758 (see section 5.2.1 of [RFC8505] which is fully compatible with 759 section 7.2 of [RFC6550]). As long as the R flag is set and this 760 router can still manage the reachability of Registered Address, the 761 6LR keeps setting the R flag in the EARO of the response NA message, 762 but the exchange of Extended Duplicate Address messages is skipped. 764 The Opaque field in the EARO hints the 6LR on the RPL Instance that 765 should be used for the DAO advertisements, and for the forwarding of 766 packets sourced at the registered address when there is no RPL Packet 767 Information (RPI) in the packet, in which case the 6LR SHOULD add one 768 to the packet. if the "I" field is not zero, then the 6LR MUST 769 consider that the Opaque field is zero. If the Opaque field is not 770 set to zero, then it should carry a RPLInstanceID for the Instance 771 suggested by the 6LN. If the 6LR does not participate to the 772 associated Instance, then the 6LR MUST consider that the Opaque field 773 is empty. If the Opaque field is empty, the 6LR is free to use the 774 default Instance (zero) for the registered address or to select an 775 Instance of its choice; else, that is if the 6LR participates to the 776 suggested Instance, then the 6LR SHOULD use that Instance for the 777 registered address. 779 Upon a successful NS/NA(EARO) exchange: if the R flag was set in the 780 EARO of the NS message, then the 6LR SHOULD inject the Registered 781 Address in RPL by sending a DAO message on behalf of the 6LN; else 782 the 6LR MUST NOT inject the Registered Address into RPL. 784 The DAO message advertising the Registered Address MUST be 785 constructed as follows: 787 o The Registered Address is placed in a RPL Target Option in the DAO 788 message as the Target Prefix, and the Prefix Length is set to 128; 790 o the External 'E' flag in the Transit Information Option (TIO) 791 associated to the Target Option is set to indicate that the 6LR 792 redistributes an external target into the RPL network. When the 793 Root has to use an IP-in-IP [I-D.ietf-roll-useofrplinfo], then 794 this flag indicates the IP-in-IP should be addressed to this node; 796 o the Path Lifetime in the TIO is computed from the Lifetime in the 797 EARO Option to adapt it to the Lifetime Units used in the RPL 798 operation. Note that if the lifetime is 0, then the 6LR generates 799 a No-Path DAO message that cleans up the routes down to the 800 Address of the 6LN; 802 o the Path Sequence in the TIO is set to the TID value found in the 803 EARO option; 805 o Additionally, in Non-Storing Mode the 6LR indicates one of its 806 global IPv6 unicast addresses as the Parent Address in the TIO. 808 If a DAO-ACK is not requested, or has a Status that is less than 128, 809 indicating the DAO was accepted, respectively by a parent in Storing 810 Mode or by the Root in non-Storing Mode,, the 6LR replies with a 811 NA(EARO) to the RUL with a status of 0 (Success). 813 In case of a DAO-ACK or a DCO with a status of 132 (Validation 814 Requested) the 6LR challenges the 6LN for ownership of the address, 815 as described in section 6.1 of [RFC8505]. If the challenge succeeds 816 then the operations continue as normal. In particular a DAO message 817 is generated upon the NS(EARO) that proves the ownership of the 818 address. If the challenge failed the 6LR MUST refrain from injecting 819 the address in RPL and may take actions to protect itself against DoS 820 attacks by a rogue 6LN, see Section 11 822 Other status values above 128 indicate that the 6LR failed to inject 823 the address into the RPL network. In that case the the 6LR MUST send 824 a NA(EARO) to the RUL with the mapped Status value. If for any other 825 reason the 6LR fails to inject the address into the RPL network, the 826 6LR SHOULD send a NA(EARO) to the RUL with a status of 2 (Out of 827 Storage) which indicates a possibility to retry later. 829 If a 6LR receives a valid NS(EARO) message with the R flag reset and 830 the 6LR was redistributing the Registered Address due to previous 831 NS(EARO) messages with the flag set, then it MUST stop injecting the 832 address. It is up to the Registering Node to maintain the 833 corresponding route from then on, either keeping it active by sending 834 further DAO messages, or destroying it using a No-Path DAO. 836 Upon a DCO message indicating that the address of a RUL should be 837 removed from the routing table, the 6LR issues an asynchronous 838 NA(EARO) to the RUL with the mapped Status value. 840 8.2.3. By the RPL Root 842 In RPL Storing Mode of Operation (MOP), the DAO message is propagated 843 from child to parent all the way to the Root along the DODAG, 844 populating routing state as it goes. In Non-Storing Mode, The DAO 845 message is sent directly to the RPL Root. Upon reception of a DAO 846 message, for each RPL Target option that creates or updates an 847 existing RPL state: 849 o the Root notifies the 6LBR using an internal API if they are co- 850 located, or performs an EDAR/EDAC exchange on behalf of the 6LR if 851 they are separated. If the Target option transports a ROVR, then 852 the Root MUST use it to build a full EDAR message as the 6LR 853 would. Else, a keep-alive EDAR is used with the ROVR field set to 854 zero. 856 An EDAR message MUST be constructed as follows: 858 o The Target IPv6 address from in the RPL Target Option is placed in 859 the Registered Address field of the EDAR message and in the Target 860 field of the NS message, respectively; 862 o the Registration Lifetime is adapted from the Path Lifetime in the 863 TIO by converting the Lifetime Units used in RPL into units of 60 864 seconds used in the 6LoWPAN ND messages; 866 o the RPL Root indicates its own MAC Address as Source Link Layer 867 Address (SLLA) in the NS(EARO); 869 o the TID value is set to the Path Sequence in the TIO and indicated 870 with an ICMP code of 1 in the EDAR message; 872 o when present in the RPL Target option, the ROVR field is used as 873 is in the EDAR and the ICMP Code Suffix is set to the appropriate 874 value as shown in Table 4 of [RFC8505] depending on the length of 875 the ROVR field. If it is not present the ROVR field in the EDAR 876 is set to zero indicating that this is a keep-alive EDAR. The 877 actual value of the ROVR for that registration is expected from 878 the 6LBR in the response EDAC. 880 Upon a Status value in an EDAC message that is not "Success", the 881 Root SHOULD destroy the formed paths using either a DAO-ACK (in Non- 882 Storing Mode) or a DCO downwards as specified in 883 [I-D.ietf-roll-efficient-npdao]. Failure to destroy the former path 884 would result in Stale routing state and local black holes if the 885 address belongs to another party elsewhere in the network. The RPL 886 Status value that maps the 6LowpAN ND status value MUST be placed in 887 the DCO. 889 8.2.4. By the 6LBR 891 Upon reception of an EDAR message with the ROVR field is set to zero 892 indicating a keep-alive EDAR, the 6LBR checks whether an entry exists 893 for the and computes whether the TID in the DAR message is fresher 894 than that in the entry as prescribed in section 4.2.1. of [RFC8505]. 896 If the entry does not exist, the 6LBR does not create the entry, and 897 answers with a Status "Removed" in the EDAC message. 899 If the entry exists but is not fresher, the 6LBR does not update the 900 entry, and answers with a Status "Success" in the EDAC message. 902 If the entry exists and the TID in the DAR message is fresher, the 903 6LBR updates the TID in the entry, and if the lifetime of the entry 904 is extended by the Registration Lifetime in the DAR message, it also 905 updates the lifetime of the entry. In that case, the 6LBR replies 906 with a Status "Success" in the DAC message. 908 The EDAC that is constructed is the same as if the keep-alive EDAR 909 was a full EDAR, and includes the ROVR that is associated to the 910 registration. 912 9. Protocol Operations for Multicast Addresses 914 Section 12 of [RFC6550] details the RPL support for multicast flows. 915 This support is not source-specific and only operates as an extension 916 to the Storing Mode of Operation for unicast packets. Note that it 917 is the RPL model that the multicast packet is passed as a Layer-2 918 unicast to each if the interested children. This remains true when 919 forwarding between the 6LR and the listener 6LN. 921 "Multicast Listener Discovery (MLD) for IPv6" [RFC2710] and its 922 updated version "Multicast Listener Discovery Version 2 (MLDv2) for 923 IPv6" [RFC3810] provide an interface for a listener to register to 924 multicast flows. MLDv2 is backwards compatible with MLD, and adds in 925 particular the capability to filter the sources via black lists and 926 white lists. In the MLD model, the router is a "querier" and the 927 host is a multicast listener that registers to the querier to obtain 928 copies of the particular flows it is interested in. 930 On the first registration, as illustrated in Figure 6, the 6LN, as an 931 MLD listener, sends an unsolicited Report to the 6LR in order to 932 start receiving the flow immediately. Since multicast Layer-2 933 messages are avoided, it is important that the asynchronous messages 934 for unsolicited Report and Done are sent reliably, for instance using 935 an Layer-2 acknoledgement, or attempted multiple times. 937 The 6LR acts as a generic MLD querier and generates a DAO for the 938 multicast target. The lifetime of the DAO is set to be in the order 939 of the Query Interval, yet larger to account for variable propagation 940 delays. 942 The Root proxies the MLD echange as listener with the 6BBR acting as 943 the querier, so as to get packets from a source external to the RPL 944 domain. Upon a DAO with a multicast target, the RPL Root checks if 945 it is already registered as a listener for that address, and if not, 946 it performs its own unsolicited Report for the multicast target. 948 6LN 6LR Root 6LBR 949 | | | | 950 | unsolicited Report | | | 951 |------------------->| | | 952 | | | | 953 | | DAO | | 954 | |-------------->| | 955 | | DAO-ACK | | 956 | |<--------------| | 957 | | | | 958 | | | unsolicited Report | 959 | | |------------------->| 960 | | | | 961 | | | | 963 Figure 6: First Multicast Registration Flow 965 A re-registration is pulled by 6LR acting as querier. Note that the 966 message may sent unicast to all the known individual listeners. Upon 967 a time out of the Query Interval, the 6LR sends a Query to each of 968 its listeners, and gets a Report back that is mapped into a DAO, as 969 illustrated in Figure 7, 971 6LN 6LR Root 6LBR 972 | | | | 973 | Query | | | 974 |<-------------------| | | 975 | Report | | | 976 |------------------->| | | 977 | | DAO | | 978 | |-------------->| | 979 | | DAO-ACK | | 980 | |<--------------| | 981 | | | | 982 | | | Query | 983 | | |<-------------------| 984 | | | Report | 985 | | |------------------->| 986 | | | | 987 | | | | 989 Figure 7: Next Registration Flow 991 Note that any of the functions 6LR, Root and 6LBR might be collapsed 992 in a single node, in which case the flow above happens internally, 993 and possibly through internal API calls as opposed to messaging. 995 10. Implementation Status 997 11. Security Considerations 999 The LLN nodes depend on the 6LBR and the RPL participants for their 1000 operation. A trust model must be put in place to ensure that the 1001 right devices are acting in these roles, so as to avoid threats such 1002 as black-holing, (see [RFC7416] section 7) or bombing attack whereby 1003 an impersonated 6LBR would destroy state in the network by using the 1004 "Removed" Status code. This trust model could be at a minimum based 1005 on a Layer-2 access control, or could provide role validation as 1006 well. This is a generic 6LoWPAN requirement, see Req5.1 in 1007 Appendix of [RFC8505]. 1009 The keep-alive EDAR message does not carry a valid Registration 1010 Unique ID [RFC8505] and it cannot be used to create a binding state 1011 in the 6LBR. The 6LBR MUST NOT create an entry based on a keep-alive 1012 EDAR that does not match an existing entry. All it can do is refresh 1013 the lifetime and the TID of an existing entry. 1015 At the time of this writing RPL does not have a zerotrust model 1016 whereby the it is possible to validate the origin of an address that 1017 is injected in a DAO. This specification makes a first step in that 1018 direction by allowing the Root to challenge the RUL by the 6LR that 1019 serves it. 1021 12. IANA Considerations 1023 12.1. RPL Target Option Flags 1025 Section 20.15 of [RFC6550] creates a registry for the 8-bit RPL 1026 Target Option Flags field. This specification reduces the field to 4 1027 bits. The IANA is requested to reduce the size of the registry 1028 accordingly. 1030 12.2. New Subsubregistry for the Status values of the RPL DAO-ACK 1031 Message 1033 This specification creates a new subsubregistry for the Status values 1034 of the RPL DAO-ACK Message, under the ICMPv6 parameters registry. 1036 o Possible values are 8-bit unsigned integers (0..255). 1038 o Registration procedure is "Standards Action" [RFC8126]. 1040 o Initial allocation is as indicated in Table 1: 1042 +---------+--------------------------------------+----------------+ 1043 | Value | Meaning | Defining Spec | 1044 +---------+--------------------------------------+----------------+ 1045 | 0 | Unqualified acceptance | RFC6550 | 1046 | | | | 1047 | 1-127 | Reserved for Warning Codes | RFC6550 | 1048 | | | | 1049 | 128 | Duplicate Address | This RFC | 1050 | | | | 1051 | 129 | Out of Storage | This RFC | 1052 | | | | 1053 | 130 | Moved | This RFC | 1054 | | | | 1055 | 131 | Removed | This RFC | 1056 | | | | 1057 | 132 | Validation Requested | This RFC | 1058 | | | | 1059 | 133 | Duplicate Source Address | This RFC | 1060 | | | | 1061 | 134 | Invalid Source Address | This RFC | 1062 | | | | 1063 | 135 | Address topologically incorrect | This RFC | 1064 | | | | 1065 | 136 | 6LBR Registry saturated | This RFC | 1066 | | | | 1067 | 137 | Validation Failed | This RFC | 1068 | | | | 1069 | 138-192 | Reserved for 6LoWPAN ND code mapping | This RFC | 1070 | | | | 1071 | 193-255 | Reserved for other Rejection Codes | RFC6550 | 1072 +---------+--------------------------------------+----------------+ 1074 Table 1: Status values of the RPL DAO-ACK Message 1076 13. Acknowledgments 1078 The authors wish to thank Georgios Papadopoulos for their early 1079 reviews of and contributions to this document 1081 14. References 1083 14.1. Normative References 1085 [I-D.ietf-6lo-ap-nd] 1086 Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, 1087 "Address Protected Neighbor Discovery for Low-power and 1088 Lossy Networks", draft-ietf-6lo-ap-nd-12 (work in 1089 progress), April 2019. 1091 [I-D.ietf-roll-efficient-npdao] 1092 Jadhav, R., Thubert, P., Sahoo, R., and Z. Cao, "Efficient 1093 Route Invalidation", draft-ietf-roll-efficient-npdao-15 1094 (work in progress), July 2019. 1096 [I-D.ietf-roll-useofrplinfo] 1097 Robles, I., Richardson, M., and P. Thubert, "Using RPL 1098 Option Type, Routing Header for Source Routes and IPv6-in- 1099 IPv6 encapsulation in the RPL Data Plane", draft-ietf- 1100 roll-useofrplinfo-31 (work in progress), August 2019. 1102 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1103 Requirement Levels", BCP 14, RFC 2119, 1104 DOI 10.17487/RFC2119, March 1997, 1105 . 1107 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1108 Listener Discovery (MLD) for IPv6", RFC 2710, 1109 DOI 10.17487/RFC2710, October 1999, 1110 . 1112 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1113 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1114 DOI 10.17487/RFC3810, June 2004, 1115 . 1117 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1118 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1119 DOI 10.17487/RFC4861, September 2007, 1120 . 1122 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1123 Address Autoconfiguration", RFC 4862, 1124 DOI 10.17487/RFC4862, September 2007, 1125 . 1127 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 1128 over Low-Power Wireless Personal Area Networks (6LoWPANs): 1129 Overview, Assumptions, Problem Statement, and Goals", 1130 RFC 4919, DOI 10.17487/RFC4919, August 2007, 1131 . 1133 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1134 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1135 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1136 Low-Power and Lossy Networks", RFC 6550, 1137 DOI 10.17487/RFC6550, March 2012, 1138 . 1140 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 1141 Power and Lossy Networks (RPL) Option for Carrying RPL 1142 Information in Data-Plane Datagrams", RFC 6553, 1143 DOI 10.17487/RFC6553, March 2012, 1144 . 1146 [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem 1147 Statement and Requirements for IPv6 over Low-Power 1148 Wireless Personal Area Network (6LoWPAN) Routing", 1149 RFC 6606, DOI 10.17487/RFC6606, May 2012, 1150 . 1152 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1153 Bormann, "Neighbor Discovery Optimization for IPv6 over 1154 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1155 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1156 . 1158 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1159 Writing an IANA Considerations Section in RFCs", BCP 26, 1160 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1161 . 1163 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 1164 "IPv6 over Low-Power Wireless Personal Area Network 1165 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 1166 April 2017, . 1168 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1169 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1170 May 2017, . 1172 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1173 (IPv6) Specification", STD 86, RFC 8200, 1174 DOI 10.17487/RFC8200, July 2017, 1175 . 1177 [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. 1178 Perkins, "Registration Extensions for IPv6 over Low-Power 1179 Wireless Personal Area Network (6LoWPAN) Neighbor 1180 Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, 1181 . 1183 14.2. Informative References 1185 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1186 C., and M. Carney, "Dynamic Host Configuration Protocol 1187 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1188 2003, . 1190 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 1191 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 1192 DOI 10.17487/RFC6282, September 2011, 1193 . 1195 [RFC6687] Tripathi, J., Ed., de Oliveira, J., Ed., and JP. Vasseur, 1196 Ed., "Performance Evaluation of the Routing Protocol for 1197 Low-Power and Lossy Networks (RPL)", RFC 6687, 1198 DOI 10.17487/RFC6687, October 2012, 1199 . 1201 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 1202 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 1203 2014, . 1205 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 1206 Constrained-Node Networks", RFC 7228, 1207 DOI 10.17487/RFC7228, May 2014, 1208 . 1210 [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., 1211 and M. Richardson, Ed., "A Security Threat Analysis for 1212 the Routing Protocol for Low-Power and Lossy Networks 1213 (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, 1214 . 1216 [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power 1217 Wireless Personal Area Network (6LoWPAN) Paging Dispatch", 1218 RFC 8025, DOI 10.17487/RFC8025, November 2016, 1219 . 1221 [RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node 1222 Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504, 1223 January 2019, . 1225 Appendix A. Example Compression 1227 Figure 8 illustrates the case in Storing mode where the packet is 1228 received from the Internet, then the Root encapsulates the packet to 1229 insert the RPI and deliver to the 6LR that is the parent and last hop 1230 to the final destination, which is not known to support [RFC8138]. 1231 The difference with the format presented in Figure 19 of [RFC8138] is 1232 the addition of a SRH-6LoRH before the RPI-6LoRH to transport the 1233 destination address of the outer IPv6 header. 1235 +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... 1236 |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP 1237 |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld 1238 +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... 1239 <-4bytes-> <- RFC 6282 -> 1240 No RPL artifact 1242 Figure 8: Encapsulation to Parent 6LR in Storing Mode 1244 In Figure 8, the source of the IP-in-IP encapsulation is the Root, so 1245 it is elided in the IP-in-IP 6LoRH. The destination is the parent 1246 6LR of the destination of the inner packet so it cannot be elided. 1247 In Storing Mode, it is placed as the single entry in an SRH-6LoRH as 1248 the first 6LoRH. Since there is a single entry so the SRH-6LoRH Size 1249 is 0. In this particular example, the 6LR address can be compressed 1250 to 2 bytes so a Type of 1 is used. It results that the total length 1251 of the SRH-6LoRH is 4 bytes. 1253 In Non-Storing Mode, the encapsulation from the Root would be similar 1254 to that represented in Figure 8 with possibly more hops in the SRH- 1255 6LoRH and possibly multiple SRH-6LoRHs if the various addresses in 1256 the routing header are not compressed to the same format. Note that 1257 on the last hop to the parent 6LR, the RH3 is consumed and removed 1258 from the compressed form, so the use of Non-Storing Mode vs. Storing 1259 Mode is indistinguishable from the packet format. 1261 Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP 1262 6LoRH is removed, all the router headers that precede it are also 1263 removed. 1265 The Paging Dispatch [RFC8025] may also be removed if there was no 1266 previous Page change to a Page other than 0 or 1, since the 1267 LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and 1268 in Page 1. The resulting packet to the destination is the inner 1269 packet compressed with [RFC6282]. 1271 Authors' Addresses 1272 Pascal Thubert (editor) 1273 Cisco Systems, Inc 1274 Building D 1275 45 Allee des Ormes - BP1200 1276 MOUGINS - Sophia Antipolis 06254 1277 FRANCE 1279 Phone: +33 497 23 26 34 1280 Email: pthubert@cisco.com 1282 Michael C. Richardson 1283 Sandelman Software Works 1285 Email: mcr+ietf@sandelman.ca 1286 URI: http://www.sandelman.ca/