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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ROLL Working Group M. Robles 3 Internet-Draft UTN-FRM/Aalto 4 Updates: 6553, 6550, 8138 (if approved) M. Richardson 5 Intended status: Standards Track SSW 6 Expires: July 14, 2021 P. Thubert 7 Cisco 8 January 10, 2021 10 Using RPI Option Type, Routing Header for Source Routes and IPv6-in-IPv6 11 encapsulation in the RPL Data Plane 12 draft-ietf-roll-useofrplinfo-43 14 Abstract 16 This document looks at different data flows through LLN (Low-Power 17 and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power 18 and Lossy Networks) is used to establish routing. The document 19 enumerates the cases where RFC6553 (RPI Option Type), RFC6554 20 (Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is 21 required in data plane. This analysis provides the basis on which to 22 design efficient compression of these headers. This document updates 23 RFC6553 adding a change to the RPI Option Type. Additionally, this 24 document updates RFC6550 defining a flag in the DIO Configuration 25 option to indicate about this change and updates RFC8138 as well to 26 consider the new Option Type when the RPL Option is decompressed. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on July 14, 2021. 45 Copyright Notice 47 Copyright (c) 2021 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 63 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4 64 2. Terminology and Requirements Language . . . . . . . . . . . . 5 65 3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6 66 4. Updates to RFC6550, RFC6553 and RFC8138 . . . . . . . . . . . 7 67 4.1. Updates to RFC6550 . . . . . . . . . . . . . . . . . . . 7 68 4.1.1. Advertising External Routes with Non-Storing Mode 69 Signaling. . . . . . . . . . . . . . . . . . . . . . 7 70 4.1.2. Configuration Options and Mode 71 of Operation . . . . . . . . . . . . . . . . . . . . 8 72 4.1.3. Indicating the new RPI in the 73 DODAG Configuration option Flag. . . . . . . . . . . 9 74 4.2. Updates to RFC6553: Indicating the new RPI Option Type. . 10 75 4.3. Updates to RFC8138: Indicating the way to decompress with 76 the new RPI Option Type. . . . . . . . . . . . . . . . . 13 77 5. Sample/reference topology . . . . . . . . . . . . . . . . . . 14 78 6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 16 79 7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 19 80 7.1. Storing Mode: Interaction between Leaf and Root . . . . . 20 81 7.1.1. SM: Example of Flow from RAL to Root . . . . . . . . 21 82 7.1.2. SM: Example of Flow from Root to RAL . . . . . . . . 22 83 7.1.3. SM: Example of Flow from Root to RUL . . . . . . . . 22 84 7.1.4. SM: Example of Flow from RUL to Root . . . . . . . . 24 85 7.2. SM: Interaction between Leaf and Internet. . . . . . . . 25 86 7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 25 87 7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 27 88 7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 28 89 7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 29 90 7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 30 91 7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 30 92 7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 31 93 7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 33 94 7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 34 95 8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 35 96 8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 37 97 8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 37 98 8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 38 99 8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 39 100 8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 40 101 8.2. Non-Storing Mode: Interaction between Leaf and Internet . 41 102 8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 41 103 8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 43 104 8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 44 105 8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 45 106 8.3. Non-SM: Interaction between leaves . . . . . . . . . . . 46 107 8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 46 108 8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 49 109 8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 51 110 8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 52 111 9. Operational Considerations of supporting 112 RUL-leaves . . . . . . . . . . . . . . . . . . . . . . . . . 53 113 10. Operational considerations of introducing 0x23 . . . . . . . 54 114 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 54 115 11.1. Option Type in RPL Option . . . . . . . . . . . . . . . 54 116 11.2. Change to the DODAG Configuration Options Flags registry 55 117 11.3. Change MOP value 7 to Reserved . . . . . . . . . . . . . 55 118 12. Security Considerations . . . . . . . . . . . . . . . . . . . 56 119 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 59 120 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 59 121 14.1. Normative References . . . . . . . . . . . . . . . . . . 59 122 14.2. Informative References . . . . . . . . . . . . . . . . . 61 123 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 63 125 1. Introduction 127 RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) 128 [RFC6550] is a routing protocol for constrained networks. [RFC6553] 129 defines the RPL Option carried within the IPv6 Hop-by-Hop Header to 130 carry the RPLInstanceID and quickly identify inconsistencies (loops) 131 in the routing topology. The RPL Option is commonly referred to as 132 the RPL Packet Information (RPI) though the RPI is the routing 133 information that is defined in [RFC6550] and transported in the RPL 134 Option. RFC6554 [RFC6554] defines the "RPL Source Route Header" 135 (RH3), an IPv6 Extension Header to deliver datagrams within a RPL 136 routing domain, particularly in non-storing mode. 138 These various items are referred to as RPL artifacts, and they are 139 seen on all of the data-plane traffic that occurs in RPL routed 140 networks; they do not in general appear on the RPL control plane 141 traffic at all which is mostly Hop-by-Hop traffic (one exception 142 being DAO messages in non-storing mode). 144 It has become clear from attempts to do multi-vendor 145 interoperability, and from a desire to compress as many of the above 146 artifacts as possible that not all implementers agree when artifacts 147 are necessary, or when they can be safely omitted, or removed. 149 The ROLL WG analyzed how [RFC2460] rules apply to storing and non- 150 storing use of RPL. The result was 24 data plane use cases. They 151 are exhaustively outlined here in order to be completely unambiguous. 152 During the processing of this document, new rules were published as 153 [RFC8200], and this document was updated to reflect the normative 154 changes in that document. 156 This document updates [RFC6553], changing the value of the Option 157 Type of the RPL Option to make [RFC8200] routers ignore this option 158 when not recognized. 160 A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a 161 mechanism for compressing RPL Option information and Routing Header 162 type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6 163 technique. 165 Most of the use cases described herein require the use of IPv6-in- 166 IPv6 packet encapsulation. When encapsulating and decapsulating 167 packets, [RFC6040] MUST be applied to map the setting of the explicit 168 congestion notification (ECN) field between inner and outer headers. 169 Additionally, [I-D.ietf-intarea-tunnels] is recommended reading to 170 explain the relationship of IP tunnels to existing protocol layers 171 and the challenges in supporting IP tunneling. 173 Non-constrained uses of RPL are not in scope of this document, and 174 applicability statements for those uses may provide different advice, 175 E.g. [I-D.ietf-anima-autonomic-control-plane]. 177 1.1. Overview 179 The rest of the document is organized as follows: Section 2 describes 180 the used terminology. Section 3 provides a RPL Overview. Section 4 181 describes the updates to RFC6553, RFC6550 and RFC 8138. Section 5 182 provides the reference topology used for the uses cases. Section 6 183 describes the use cases included. Section 7 describes the storing 184 mode cases and section 8 the non-storing mode cases. Section 9 185 describes the operational considerations of supporting RPL-unaware- 186 leaves. Section 10 depicts operational considerations for the 187 proposed change on RPI Option Type, section 11 the IANA 188 considerations and then section 12 describes the security aspects. 190 2. Terminology and Requirements Language 192 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 193 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 194 "OPTIONAL" in this document are to be interpreted as described in BCP 195 14 [RFC2119] [RFC8174] when, and only when, they appear in all 196 capitals, as shown here. 198 Terminology defined in [RFC7102] applies to this document: LLN, RPL, 199 RPL domain and ROLL. 201 Consumed: A Routing Header is consumed when the Segments Left field 202 is zero, which indicates that the destination in the IPv6 header is 203 the final destination of the packet and that the hops in the Routing 204 Header have been traversed. 206 RPL Leaf: An IPv6 host that is attached to a RPL router and obtains 207 connectivity through a RPL Destination Oriented Directed Acyclic 208 Graph (DODAG). As an IPv6 node, a RPL Leaf is expected to ignore a 209 consumed Routing Header and as an IPv6 host, it is expected to ignore 210 a Hop-by-Hop header. It results that a RPL Leaf can correctly 211 receive a packet with RPL artifacts. On the other hand, a RPL Leaf 212 is not expected to generate RPL artifacts or to support IP-in-IP 213 encapsulation. For simplification, this document uses the standalone 214 term leaf to mean a RPL leaf. 216 RPL Packet Information (RPI): The information defined abstractly in 217 [RFC6550] to be placed in IP packets. The term is commonly used, 218 including in this document, to refer to the RPL Option [RFC6553] that 219 transports that abstract information in an IPv6 Hop-by-Hop Header. 220 [RFC8138] provides an alternate (more compressed) formating for the 221 same abstract information. 223 RPL-aware-node (RAN): A device which implements RPL. Please note 224 that the device can be found inside the LLN or outside LLN. 226 RPL-Aware-Leaf(RAL): A RPL-aware-node that is also a RPL Leaf. 228 RPL-unaware-node: A device which does not implement RPL, thus the 229 device is not-RPL-aware. Please note that the device can be found 230 inside the LLN. 232 RPL-Unaware-Leaf(RUL): A RPL-unaware-node that is also a RPL Leaf. 234 6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any 235 host or router participating in a LoWPAN. This term is used when 236 referring to situations in which either a host or router can play the 237 role described.". In this document, a 6LN acts as a leaf. 239 6LoWPAN Router (6LR): [RFC6775] defines it as:" An intermediate 240 router in the LoWPAN that is able to send and receive Router 241 Advertisements (RAs) and Router Solicitations (RSs) as well as 242 forward and route IPv6 packets. 6LoWPAN routers are present only in 243 route-over topologies." 245 6LoWPAN Border Router (6LBR): [RFC6775] defines it as:"A border 246 router located at the junction of separate 6LoWPAN networks or 247 between a 6LoWPAN network and another IP network. There may be one 248 or more 6LBRs at the 6LoWPAN network boundary. A 6LBR is the 249 responsible authority for IPv6 prefix propagation for the 6LoWPAN 250 network it is serving. An isolated LoWPAN also contains a 6LBR in 251 the network, which provides the prefix(es) for the isolated network." 253 Flag Day: It is a mechanism for resolving an interoperability 254 situation (e.g. lack of interoperation between new RPI Option Type 255 (0x23) and old RPI Option Type (0x63) nodes) by making an abrupt, 256 disruptive changeover from one to the other. 258 Non-Storing Mode (Non-SM): RPL mode of operation in which the RPL- 259 aware-nodes send information to the root about their parents. Thus, 260 the root knows the topology. Because the root knows the topology, 261 the intermediate 6LRs do not maintain routing state and source 262 routing is needed. 264 Storing Mode (SM): RPL mode of operation in which RPL-aware-nodes 265 (6LRs) maintain routing state (of the children) so that source 266 routing is not needed. 268 Note: Due to lack of space in some figures (tables) we refer to IPv6- 269 in-IPv6 as IP6-IP6. 271 3. RPL Overview 273 RPL defines the RPL Control messages (control plane), a new ICMPv6 274 [RFC4443] message with Type 155. DIS (DODAG Information 275 Solicitation), DIO (DODAG Information Object) and DAO (Destination 276 Advertisement Object) messages are all RPL Control messages but with 277 different Code values. A RPL Stack is shown in Figure 1. 279 +--------------+ 280 | Upper Layers | 281 | | 282 +--------------+ 283 | RPL | 284 | | 285 +--------------+ 286 | ICMPv6 | 287 | | 288 +--------------+ 289 | IPv6 | 290 | | 291 +--------------+ 292 | 6LoWPAN | 293 | | 294 +--------------+ 295 | PHY-MAC | 296 | | 297 +--------------+ 299 Figure 1: RPL Stack. 301 RPL supports two modes of Downward internal traffic: in storing mode 302 (SM), it is fully stateful; in non-storing mode (Non-SM), it is fully 303 source routed. A RPL Instance is either fully storing or fully non- 304 storing, i.e. a RPL Instance with a combination of a fully storing 305 and non-storing nodes is not supported with the current 306 specifications at the time of writing this document. External routes 307 are advertised with non-storing-mode messaging even in a storing mode 308 network, see Section 4.1.1 310 4. Updates to RFC6550, RFC6553 and RFC8138 312 4.1. Updates to RFC6550 314 4.1.1. Advertising External Routes with Non-Storing Mode Signaling. 316 Section 6.7.8. of [RFC6550] introduces the 'E' flag that is set to 317 indicate that the 6LR that generates the DAO redistributes external 318 targets into the RPL network. An external Target is a Target that 319 has been learned through an alternate protocol, for instance a route 320 to a prefix that is outside the RPL domain but reachable via a 6LR. 321 Being outside of the RPL domain, a node that is reached via an 322 external target cannot be guaranteed to ignore the RPL artifacts and 323 cannot be expected to process the [RFC8138] compression correctly. 324 This means that the RPL artifacts should be contained in an IP-in-IP 325 encapsulation that is removed by the 6LR, and that any remaining 326 compression should be expanded by the 6LR before it forwards a packet 327 outside the RPL domain. 329 This specification updates [RFC6550] to RECOMMEND that external 330 targets are advertised using Non-Storing Mode DAO messaging even in a 331 Storing-Mode network. This way, external routes are not advertised 332 within the DODAG and all packets to an external target reach the Root 333 like normal Non-Storing Mode traffic. The Non-Storing Mode DAO 334 informs the Root of the address of the 6LR that injects the external 335 route, and the root uses IP-in-IP encapsulation to that 6LR, which 336 terminates the IP-in-IP tunnel and forwards the original packet 337 outside the RPL domain free of RPL artifacts. 339 In the other direction, for traffic coming from an external target 340 into the LLN, the parent (6LR) that injects the traffic always 341 encapsulates to the root. This whole operation is transparent to 342 intermediate routers that only see traffic between the 6LR and the 343 Root, and only the Root and the 6LRs that inject external routes in 344 the network need to be upgraded to add this function to the network. 346 A RUL is a special case of external target when the target is 347 actually a host and it is known to support a consumed Routing Header 348 and to ignore a Hop-by-Hop header as prescribed by [RFC8200]. The 349 target may have been learned through an external routing protocol or 350 may have been registered to the 6LR using [RFC8505]. 352 In order to enable IP-in-IP all the way to a 6LN, it is beneficial 353 that the 6LN supports decapsulating IP-in-IP, but that is not assumed 354 by [RFC8504]. If the 6LN is a RUL, the Root that encapsulates a 355 packet SHOULD terminate the tunnel at a parent 6LR unless it is aware 356 that the RUL supports IP-in-IP decapsulation. 358 A node that is reachable over an external route is not expected to 359 support [RFC8138]. Whether a decapsulation took place or not and 360 even when the 6LR is delivering the packet to a RUL, the 6LR that 361 injected an external route MUST uncompress the packet before 362 forwarding over that external route. 364 4.1.2. Configuration Options and Mode of Operation 366 Section 6.7.6 of RFC6550 describes the DODAG Configuration Option as 367 containing a series of Flags in the first octet of the payload. 369 Anticipating future work to revise RPL relating to how the LLN and 370 DODAG are configured, this document renames the DODAG Configuration 371 Option Flags registry so that it applies to Mode of Operation (MOP) 372 values zero (0) to six (6) only, leaving the flags unassigned for MOP 373 value seven (7).The MOP is described in RFC6550 section 6.3.1. 375 In addition, this document reserves MOP value 7 for future expansion. 377 See Sections 11.2 and 11.3. 379 4.1.3. Indicating the new RPI in the DODAG Configuration option Flag. 381 In order to avoid a Flag Day caused by lack of interoperation between 382 new RPI Option Type (0x23) and old RPI Option Type (0x63) nodes, this 383 section defines a flag in the DIO Configuration option, to indicate 384 when the new RPI Option Type can be safely used. This means, the 385 flag is going to indicate the value of Option Type that the network 386 will be using for the RPL Option. Thus, when a node joins to a 387 network it will know which value to use. With this, RPL-capable 388 nodes know if it is safe to use 0x23 when creating a new RPL Option. 389 A node that forwards a packet with an RPI MUST NOT modify the Option 390 Type of the RPL Option. 392 This is done using a DODAG Configuration option flag which will 393 signal "RPI 0x23 enable" and propagate through the network. 394 Section 6.3.1. of [RFC6550] defines a 3-bit Mode of Operation (MOP) 395 in the DIO Base Object. The flag is defined only for MOP value 396 between 0 to 6. 398 For a MOP value of 7, a node MUST use the RPI 0x23 option. 400 As stated in [RFC6550] the DODAG Configuration option is present in 401 DIO messages. The DODAG Configuration option distributes 402 configuration information. It is generally static, and does not 403 change within the DODAG. This information is configured at the DODAG 404 root and distributed throughout the DODAG with the DODAG 405 Configuration option. Nodes other than the DODAG root do not modify 406 this information when propagating the DODAG Configuration option. 408 Currently, the DODAG Configuration option in [RFC6550] states: "the 409 unused bits MUST be initialized to zero by the sender and MUST be 410 ignored by the receiver". If the flag is received with a value zero 411 (which is the default), then new nodes will remain in RFC6553 412 Compatible Mode; originating traffic with the old-RPI Option Type 413 (0x63) value. If the flag is received with a value of 1, then the 414 value for the RPL Option MUST be set to 0x23. 416 Bit number three of the flag field in the DODAG Configuration option 417 is to be used as shown in Figure 2 (which is the same as Figure 39 in 418 Section 11 and is shown here for convenience): 420 +------------+-----------------+---------------+ 421 | Bit number | Description | Reference | 422 +------------+-----------------+---------------+ 423 | 3 | RPI 0x23 enable | This document | 424 +------------+-----------------+---------------+ 426 Figure 2: DODAG Configuration option Flag to indicate the RPI-flag- 427 day. 429 In the case of reboot, the node (6LN or 6LR) does not remember the 430 RPI Option Type (i.e., whether or not the flag is set), so the node 431 will not trigger DIO messages until a DIO message is received 432 indicating the RPI value to be used. The node will use the value 433 0x23 if the network supports this feature. 435 4.2. Updates to RFC6553: Indicating the new RPI Option Type. 437 This modification is required in order to be able to send, for 438 example, IPv6 packets from a RPL-Aware-Leaf to a RPL-unaware node 439 through Internet (see Section 7.2.1), without requiring IPv6-in-IPv6 440 encapsulation. 442 [RFC6553] (Section 6, Page 7) states as shown in Figure 3, that in 443 the Option Type field of the RPL Option, the two high order bits must 444 be set to '01' and the third bit is equal to '1'. The first two bits 445 indicate that the IPv6 node must discard the packet if it doesn't 446 recognize the Option Type, and the third bit indicates that the 447 Option Data may change in route. The remaining bits serve as the 448 Option Type. 450 +-------+-------------------+----------------+-----------+ 451 | Hex | Binary Value | Description | Reference | 452 + Value +-------------------+ + + 453 | | act | chg | rest | | | 454 +-------+-----+-----+-------+----------------+-----------+ 455 | 0x63 | 01 | 1 | 00011 | RPL Option | [RFC6553] | 456 +-------+-----+-----+-------+----------------+-----------+ 458 Figure 3: Option Type in RPL Option. 460 This document illustrates that it is not always possible to know for 461 sure at the source that a packet will only travel within the RPL 462 domain or may leave it. 464 At the time [RFC6553] was published, leaking a Hop-by-Hop header in 465 the outer IPv6 header chain could potentially impact core routers in 466 the internet. So at that time, it was decided to encapsulate any 467 packet with a RPL Option using IPv6-in-IPv6 in all cases where it was 468 unclear whether the packet would remain within the RPL domain. In 469 the exception case where a packet would still leak, the Option Type 470 would ensure that the first router in the Internet that does not 471 recognize the option would drop the packet and protect the rest of 472 the network. 474 Even with [RFC8138], where the IPv6-in-IPv6 header is compressed, 475 this approach yields extra bytes in a packet; this means consuming 476 more energy, more bandwidth, incurring higher chances of loss and 477 possibly causing a fragmentation at the 6LoWPAN level. This impacts 478 the daily operation of constrained devices for a case that generally 479 does not happen and would not heavily impact the core anyway. 481 While intention was and remains that the Hop-by-Hop header with a RPL 482 Option should be confined within the RPL domain, this specification 483 modifies this behavior in order to reduce the dependency on IPv6-in- 484 IPv6 and protect the constrained devices. Section 4 of [RFC8200] 485 clarifies the behaviour of routers in the Internet as follows: "it is 486 now expected that nodes along a packet's delivery path only examine 487 and process the Hop-by-Hop Options header if explicitly configured to 488 do so". 490 When unclear about the travel of a packet, it becomes preferable for 491 a source not to encapsulate, accepting the fact that the packet may 492 leave the RPL domain on its way to its destination. In that event, 493 the packet should reach its destination and should not be discarded 494 by the first node that does not recognize the RPL Option. But with 495 the current value of the Option Type, if a node in the Internet is 496 configured to process the Hop-by-Hop header, and if such node 497 encounters an option with the first two bits set to 01 and conforms 498 to [RFC8200], it will drop the packet. Host systems should do the 499 same, irrespective of the configuration. 501 Thus, this document updates the Option Type of the RPL Option 502 [RFC6553], naming it RPI Option Type for simplicity, to (Figure 4): 503 the two high order bits MUST be set to '00' and the third bit is 504 equal to '1'. The first two bits indicate that the IPv6 node MUST 505 skip over this option and continue processing the header ([RFC8200] 506 Section 4.2) if it doesn't recognize the Option Type, and the third 507 bit continues to be set to indicate that the Option Data may change 508 en route. The rightmost five bits remain at 0x3(00011). This 509 ensures that a packet that leaves the RPL domain of an LLN (or that 510 leaves the LLN entirely) will not be discarded when it contains the 511 RPL Option. 513 With the new Option Type, if an IPv6 (intermediate) node (RPL-not- 514 capable) receives a packet with a RPL Option, it should ignore the 515 Hop-by-Hop RPL Option (skip over this option and continue processing 516 the header). This is relevant, as it was mentioned previously, in 517 the case that there is a flow from RAL to Internet (see 518 Section 7.2.1). 520 This is a significant update to [RFC6553]. 522 +-------+-------------------+-------------+------------+ 523 | Hex | Binary Value | Description | Reference | 524 + Value +-------------------+ + + 525 | | act | chg | rest | | | 526 +-------+-----+-----+-------+-------------+------------+ 527 | 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)| 528 +-------+-----+-----+-------+-------------+------------+ 530 Figure 4: Revised Option Type in RPL Option. (*)represents this 531 document 533 Without the signaling described below, this change would otherwise 534 create a lack of interoperation (flag day) for existing networks 535 which are currently using 0x63 as the RPI Option Type value. A move 536 to 0x23 will not be understood by those networks. It is suggested 537 that RPL implementations accept both 0x63 and 0x23 when processing 538 the header. 540 When forwarding packets, implementations SHOULD use the same value of 541 RPI Type as was received. This is required because the RPI Option 542 Type does not change en route ([RFC8200] - Section 4.2). It allows 543 the network to be incrementally upgraded and allows the DODAG root to 544 know which parts of the network have been upgraded. 546 When originating new packets, implementations should have an option 547 to determine which value to originate with, this option is controlled 548 by the DIO Configuration option (Section Section 4.1.3). 550 The change of RPI Option Type from 0x63 to 0x23, makes all [RFC8200] 551 Section 4.2 compliant nodes tolerant of the RPL artifacts. There is 552 no longer a need to remove the artifacts when sending traffic to the 553 Internet. This change clarifies when to use IPv6-in-IPv6 headers, 554 and how to address them: The Hop-by-Hop Options header containing the 555 RPI MUST always be added when 6LRs originate packets (without IPv6- 556 in-IPv6 headers), and IPv6-in-IPv6 headers MUST always be added when 557 a 6LR finds that it needs to insert a Hop-by-Hop Options header 558 containing the RPL Option. The IPv6-in-IPv6 header is to be 559 addressed to the RPL root when on the way up, and to the end-host 560 when on the way down. 562 In the non-storing case, dealing with not-RPL aware leaf nodes is 563 much easier as the 6LBR (DODAG root) has complete knowledge about the 564 connectivity of all DODAG nodes, and all traffic flows through the 565 root node. 567 The 6LBR can recognize not-RPL aware leaf nodes because it will 568 receive a DAO about that node from the 6LR immediately above that 569 not-RPL aware node. 571 The non-storing mode case does not require the type change from 0x63 572 to 0x23, as the root can always create the right packet. The type 573 change does not adversely affect the non-storing case.(see 574 Section 4.1.3) 576 4.3. Updates to RFC8138: Indicating the way to decompress with the new 577 RPI Option Type. 579 This modification is required in order to be able to decompress the 580 RPL Option with the new Option Type of 0x23. 582 RPI-6LoRH header provides a compressed form for the RPL RPI; see 583 [RFC8138], Section 6. A node that is decompressing this header MUST 584 decompress using the RPI Option Type that is currently active: that 585 is, a choice between 0x23 (new) and 0x63 (old). The node will know 586 which to use based upon the presence of the flag in the DODAG 587 Configuration option defined in Section 4.1.3. E.g. If the network 588 is in 0x23 mode (by DIO option), then it should be decompressed to 589 0x23. 591 [RFC8138] section 7 documents how to compress the IPv6-in-IPv6 592 header. 594 There are potential significant advantages to having a single code 595 path that always processes IPv6-in-IPv6 headers with no conditional 596 branches. 598 In Storing Mode, the scenarios where the flow goes from RAL to RUL 599 and RUL to RUL include compression of the IPv6-in-IPv6 and RPI 600 headers. The use of the IPv6-in-IPv6 header is MANDATORY in this 601 case, and it SHOULD be compressed with [RFC8138] section 7. Figure 5 602 illustrates the case in Storing mode where the packet is received 603 from the Internet, then the root encapsulates the packet to insert 604 the RPI. In that example, the leaf is not known to support RFC 8138, 605 and the packet is encapsulated to the 6LR that is the parent and last 606 hop to the final destination. 608 +-+ ... -+-+ ... +-+- ... -+-+- +-+-+-+ ... +-+-+ ... -+++ ... +-... 609 |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP 610 |Page 1 |Type1 S=0| 6LoRH |6LoRH |LOWPAN_IPHC| UDP | hdr |Payld 611 +-+ ... -+-+ ... +-+- ... -+-+-.+-+-+-+-+ ... +-+-+ ... -+ ... +-... 612 <-4bytes-> <- RFC 6282 -> 613 No RPL artifact 615 Figure 5: RPI Inserted by the Root in Storing Mode 617 In Figure 5, the source of the IPv6-in-IPv6 encapsulation is the 618 Root, so it is elided in the IP-in-IP 6LoRH. The destination is the 619 parent 6LR of the destination of the inner packet so it cannot be 620 elided. It is placed as the single entry in an SRH-6LoRH as the 621 first 6LoRH. There is a single entry so the SRH-6LoRH Size is 0. In 622 that example, the type is 1 so the 6LR address is compressed to 2 623 bytes. It results that the total length of the SRH-6LoRH is 4 bytes. 624 Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP 625 6LoRH is removed, all the router headers that precede it are also 626 removed. The Paging Dispatch [RFC8025] may also be removed if there 627 was no previous Page change to a Page other than 0 or 1, since the 628 LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and 629 in Page 1. The resulting packet to the destination is the inner 630 packet compressed with [RFC6282]. 632 5. Sample/reference topology 634 A RPL network in general is composed of a 6LBR, a Backbone Router 635 (6BBR), a 6LR and a 6LN as a leaf logically organized in a DODAG 636 structure. 638 Figure 6 shows the reference RPL Topology for this document. The 639 letters above the nodes are there so that they may be referenced in 640 subsequent sections. In the figure, 6LR represents a full router 641 node. The 6LN is a RPL aware router, or host (as a leaf). 642 Additionally, for simplification purposes, it is supposed that the 643 6LBR has direct access to Internet and is the root of the DODAG, thus 644 the 6BBR is not present in the figure. 646 The 6LN leaves (RAL) marked as (F, H and I) are RPL nodes with no 647 children hosts. 649 The leaves marked as RUL (G and J) are devices that do not speak RPL 650 at all (not-RPL-aware), but use Router-Advertisements, 6LowPAN DAR/ 651 DAC and 6LoWPAN ND only to participate in the network [RFC8505]. In 652 the document these leaves (G and J) are also referred to as a RUL. 654 The 6LBR ("A") in the figure is the root of the Global DODAG. 656 +------------+ 657 | INTERNET ----------+ 658 | | | 659 +------------+ | 660 | 661 | 662 | 663 A | 664 +-------+ 665 |6LBR | 666 +-----------|(root) |-------+ 667 | +-------+ | 668 | | 669 | | 670 | | 671 | | 672 | B |C 673 +---|---+ +---|---+ 674 | 6LR | | 6LR | 675 +---------| |--+ +--- ---+ 676 | +-------+ | | +-------+ | 677 | | | | 678 | | | | 679 | | | | 680 | | | | 681 | D | E | | 682 +-|-----+ +---|---+ | | 683 | 6LR | | 6LR | | | 684 | | +------ | | | 685 +---|---+ | +---|---+ | | 686 | | | | | 687 | | +--+ | | 688 | | | | | 689 | | | | | 690 | | | I | J | 691 F | | G | H | | 692 +-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+ 693 | RAL | | RUL | | RAL | | RAL | | RUL | 694 | 6LN | | 6LN | | 6LN | | 6LN | | 6LN | 695 +-------+ +-------+ +------+ +-------+ +-------+ 697 Figure 6: A reference RPL Topology. 699 6. Use cases 701 In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6 702 encapsulation are going to be analyzed for a number of representative 703 traffic flows. 705 The use cases describe the communication in the following cases: - 706 Between RPL-aware-nodes with the root (6LBR) - Between RPL-aware- 707 nodes with the Internet - Between RUL nodes within the LLN (e.g. see 708 Section 7.1.4) - Inside of the LLN when the final destination address 709 resides outside of the LLN (e.g. see Section 7.2.3). 711 The use cases are as follows: 713 Interaction between Leaf and Root: 715 RAL to root 717 root to RAL 719 RUL to root 721 root to RUL 723 Interaction between Leaf and Internet: 725 RAL to Internet 727 Internet to RAL 729 RUL to Internet 731 Internet to RUL 733 Interaction between leaves: 735 RAL to RAL 737 RAL to RUL 739 RUL to RAL 741 RUL to RUL 743 This document is consistent with the rule that a Header cannot be 744 inserted or removed on the fly inside an IPv6 packet that is being 745 routed. This is a fundamental precept of the IPv6 architecture as 746 outlined in [RFC8200]. 748 As the rank information in the RPI artifact is changed at each hop, 749 it will typically be zero when it arrives at the DODAG root. The 750 DODAG root MUST force it to zero when passing the packet out to the 751 Internet. The Internet will therefore not see any SenderRank 752 information. 754 Despite being legal to leave the RPI artifact in place, an 755 intermediate router that needs to add an extension header (e.g. RH3 756 or RPL Option) MUST still encapsulate the packet in an (additional) 757 outer IP header. The new header is placed after this new outer IP 758 header. 760 A corollary is that an intermediate router can remove an RH3 or RPL 761 Option only if it is placed in an encapsulating IPv6 Header that is 762 addressed TO this intermediate router. When doing the above, the 763 whole encapsulating header must be removed. (A replacement may be 764 added). This sometimes can result in outer IP headers being 765 addressed to the next hop router using link-local address. 767 Both the RPL Option and the RH3 headers may be modified in very 768 specific ways by routers on the path of the packet without the need 769 to add and remove an encapsulating header. Both headers were 770 designed with this modification in mind, and both the RPL RH3 and the 771 RPL Option are marked mutable but recoverable: so an IPsec AH 772 security header can be applied across these headers, but it can not 773 secure the values which mutate. 775 The RPI MUST be present in every single RPL data packet. 777 Prior to [RFC8138], there was significant interest in creating an 778 exception to this rule and removing the RPI for downward flows in 779 non-storing mode. This exception covered a very small number of 780 cases, and caused significant interoperability challenges while 781 adding significant interest in the code and tests. The ability to 782 compress the RPI down to three bytes or less removes much of the 783 pressure to optimize this any further 784 [I-D.ietf-anima-autonomic-control-plane]. 786 Throughout the following subsections, the examples are described in 787 more details in the first subsections, and more concisely in the 788 later ones. 790 The uses cases are delineated based on the following IPV6 and RPL 791 mandates: 793 The RPI has to be in every packet that traverses the LLN. 795 - Because of the above requirement, packets from the Internet have 796 to be encapsulated. 798 - A Header cannot be inserted or removed on the fly inside an IPv6 799 packet that is being routed. 801 - Extension headers may not be added or removed except by the 802 sender or the receiver. 804 - RPI and RH3 headers may be modified by routers on the path of 805 the packet without the need to add and remove an encapsulating 806 header. 808 - an RH3 or RPL Option can only be removed by an intermediate 809 router if it is placed in an encapsulating IPv6 Header, which is 810 addressed to the intermediate router. 812 - Non-storing mode requires downstream encapsulation by root for 813 RH3. 815 The uses cases are delineated based on the following assumptions: 817 This document assumes that the LLN is using the no-drop RPI Option 818 Type (0x23). 820 - Each IPv6 node (including Internet routers) obeys [RFC8200], so 821 that 0x23 RPI Option Type can be safely inserted. 823 - All 6LRs obey [RFC8200]. 825 - The RPI is ignored at the IPv6 dst node (RUL). 827 - In the uses cases, we assume that the RAL supports IP-in-IP 828 encapsulation. 830 - In the uses cases, we don't assume that the RUL supports IP-in- 831 IP encapsulation. 833 - For traffic leaving a RUL, if the RUL adds an opaque RPI then 834 the 6LR as a RPL border router SHOULD rewrite the RPI to indicate 835 the selected Instance and set the flags. 837 - The description for RALs applies to RAN in general. 839 - Non-constrained uses of RPL are not in scope of this document. 841 - Compression is based on [RFC8138]. 843 - The flow label [RFC6437] is not needed in RPL. 845 7. Storing mode 847 In storing mode (SM) (fully stateful), the sender can determine if 848 the destination is inside the LLN by looking if the destination 849 address is matched by the DIO's Prefix Information Option (PIO) 850 option. 852 The following table (Figure 7) itemizes which headers are needed in 853 each of the following scenarios. It indicates whether an IPv6-in- 854 IPv6 header must be added and what destination it must be addressed 855 to: (1) the final destination (the RAL node that is the target 856 (tgt)), (2) the "root", or (3) the 6LR parent of a RUL. 858 In cases where no IPv6-in-IPv6 header is needed, the column states 859 "No", and the destination is N/A (Not Applicable). If the IPv6-in- 860 IPv6 header is needed, the column shows "must". 862 In all cases, the RPI is needed, since it identifies inconsistencies 863 (loops) in the routing topology. In general, the RH3 is not needed 864 because it is not used in storing mode. However, there is one 865 scenario (from the root to the RUL in SM) where the RH3 can be used 866 to point at the RUL (Figure 11). 868 The leaf can be a router 6LR or a host, both indicated as 6LN. The 869 root refers to the 6LBR (see Figure 6). 871 +---------------------+--------------+------------+----------------+ 872 | Interaction between | Use Case |IPv6-in-IPv6|IPv6-in-IPv6 dst| 873 +---------------------+--------------+------------+----------------+ 874 | | RAL to root | No | N/A | 875 + +--------------+------------+----------------+ 876 | Leaf - Root | root to RAL | No | N/A | 877 + +--------------+------------+----------------+ 878 | | root to RUL | must | 6LR | 879 + +--------------+------------+----------------+ 880 | | RUL to root | must | root | 881 +---------------------+--------------+------------+----------------+ 882 | | RAL to Int | may | root | 883 + +--------------+------------+----------------+ 884 | Leaf - Internet | Int to RAL | must | RAL (tgt) | 885 + +--------------+------------+----------------+ 886 | | RUL to Int | must | root | 887 + +--------------+------------+----------------+ 888 | | Int to RUL | must | 6LR | 889 +---------------------+--------------+------------+----------------+ 890 | | RAL to RAL | No | N/A | 891 | Leaf - Leaf +--------------+------------+----------------+ 892 | | RAL to RUL | No(up) | N/A | 893 | + +------------+----------------+ 894 | | | must(down) | 6LR | 895 | +--------------+------------+----------------+ 896 | | RUL to RAL | must(up) | root | 897 | | +------------+----------------+ 898 | | | must(down) | RAL | 899 | +--------------+------------+----------------+ 900 | | RUL to RUL | must(up) | root | 901 | | +------------+----------------+ 902 | | | must(down) | 6LR | 903 |---------------------+--------------+------------+----------------+ 905 Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode. 907 7.1. Storing Mode: Interaction between Leaf and Root 909 In this section is described the communication flow in storing mode 910 (SM) between, 912 RAL to root 914 root to RAL 916 RUL to root 918 root to RUL 920 7.1.1. SM: Example of Flow from RAL to Root 922 In storing mode, RFC 6553 (RPI) is used to send RPL Information 923 instanceID and rank information. 925 In this case the flow comprises: 927 RAL (6LN) --> 6LR_i --> root(6LBR) 929 For example, a communication flow could be: Node F (6LN) --> Node D 930 (6LR_i) --> Node B (6LR_i)--> Node A root(6LBR) 932 The RAL (Node F) inserts the RPI, and sends the packet to 6LR (Node 933 D) which decrements the rank in the RPI and sends the packet up. 934 When the packet arrives at 6LBR (Node A), the RPI is removed and the 935 packet is processed. 937 No IPv6-in-IPv6 header is required. 939 The RPI can be removed by the 6LBR because the packet is addressed to 940 the 6LBR. The RAL must know that it is communicating with the 6LBR 941 to make use of this scenario. The RAL can know the address of the 942 6LBR because it knows the address of the root via the DODAGID in the 943 DIO messages. 945 The Figure 8 summarizes what headers are needed for this use case. 947 +-----------+-----+-------+------+ 948 | Header | RAL | 6LR_i | 6LBR | 949 | | src | | dst | 950 +-----------+-----+-------+------+ 951 | Added | RPI | -- | -- | 952 | headers | | | | 953 +-----------+-----+-------+------+ 954 | Modified | -- | RPI | -- | 955 | headers | | | | 956 +-----------+-----+-------+------+ 957 | Removed | -- | -- | RPI | 958 | headers | | | | 959 +-----------+-----+-------+------+ 960 | Untouched | -- | -- | -- | 961 | headers | | | | 962 +-----------+-----+-------+------+ 964 Figure 8: SM: Summary of the use of headers from RAL to root 966 7.1.2. SM: Example of Flow from Root to RAL 968 In this case the flow comprises: 970 root (6LBR) --> 6LR_i --> RAL (6LN) 972 For example, a communication flow could be: Node A root(6LBR) --> 973 Node B (6LR_i) --> Node D (6LR_i) --> Node F (6LN) 975 In this case the 6LBR inserts RPI and sends the packet down, the 6LR 976 is going to increment the rank in RPI (it examines the RPLInstanceID 977 to identify the right forwarding table), the packet is processed in 978 the RAL and the RPI removed. 980 No IPv6-in-IPv6 header is required. 982 The Figure 9 summarizes what headers are needed for this use case. 984 +-----------+------+-------+-----+ 985 | Header | 6LBR | 6LR_i | RAL | 986 | | src | | dst | 987 +-----------+------+-------+-----+ 988 | Added | RPI | -- | -- | 989 | headers | | | | 990 +-----------+------+-------+-----+ 991 | Modified | -- | RPI | -- | 992 | headers | | | | 993 +-----------+------+-------+-----+ 994 | Removed | -- | -- | RPI | 995 | headers | | | | 996 +-----------+------+-------+-----+ 997 | Untouched | -- | -- | -- | 998 | headers | | | | 999 +-----------+------+-------+-----+ 1001 Figure 9: SM: Summary of the use of headers from root to RAL 1003 7.1.3. SM: Example of Flow from Root to RUL 1005 In this case the flow comprises: 1007 root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1009 For example, a communication flow could be: Node A (6LBR) --> Node B 1010 (6LR_i) --> Node E (6LR_n) --> Node G (RUL) 1012 6LR_i (Node B) represents the intermediate routers from the source 1013 (6LBR) to the destination (RUL), 1 <= i <= n, where n is the total 1014 number of routers (6LR) that the packet goes through from the 6LBR 1015 (Node A) to the RUL (Node G). 1017 The 6LBR will encapsulate the packet in an IPv6-in-IPv6 header, and 1018 prepend an RPI. The IPv6-in-IPv6 header is addressed to the 6LR 1019 parent of the RUL (6LR_n). The 6LR parent of the RUL removes the 1020 header and sends the packet to the RUL. 1022 The Figure 10 summarizes what headers are needed for this use case. 1024 +-----------+---------+---------+---------+-----+ 1025 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 1026 | | src | | | dst | 1027 +-----------+---------+---------+---------+-----+ 1028 | Added | IP6-IP6 | -- | -- | -- | 1029 | headers | RPI | | | | 1030 +-----------+---------+---------+---------+-----+ 1031 | Modified | -- | | -- | -- | 1032 | headers | | RPI | | | 1033 +-----------+---------+---------+---------+-----+ 1034 | Removed | -- | -- | IP6-IP6 | -- | 1035 | headers | | | RPI | | 1036 +-----------+---------+---------+---------+-----+ 1037 | Untouched | -- | IP6-IP6 | -- | -- | 1038 | headers | | | | | 1039 +-----------+---------+---------+---------+-----+ 1041 Figure 10: SM: Summary of the use of headers from root to RUL 1043 IP-in-IP encapsulation may be avoided for Root to RUL communication. 1044 In SM, it can be replaced by a loose RH3 header that indicates the 1045 RUL, in which case the packet is routed to the 6LR as a normal SM 1046 operation, then the 6LR forwards to the RUL based on the RH3, and the 1047 RUL ignores both the consumed RH3 and the RPI, as in Non-Storing 1048 Mode. 1050 The Figure 11 summarizes what headers are needed for this scenario. 1052 +-----------+----------+--------------+----------------+----------+ 1053 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 1054 | | src | i=(1,..,n-1) | | dst | 1055 | | | | | | 1056 +-----------+----------+--------------+----------------+----------+ 1057 | Added | RPI, RH3 | -- | -- | -- | 1058 | headers | | | | | 1059 +-----------+----------+--------------+----------------+----------+ 1060 | Modified | -- | RPI | RPI | -- | 1061 | headers | | | RH3(consumed) | | 1062 +-----------+----------+--------------+----------------+----------+ 1063 | Removed | -- | -- | -- | -- | 1064 | headers | | | | | 1065 +-----------+----------+--------------+----------------+----------+ 1066 | Untouched | -- | RH3 | -- | RPI, RH3 | 1067 | headers | | | | (both | 1068 | | | | | ignored) | 1069 +-----------+----------+--------------+----------------+----------+ 1071 Figure 11: SM: Summary of the use of headers from root to RUL without 1072 encapsulation 1074 7.1.4. SM: Example of Flow from RUL to Root 1076 In this case the flow comprises: 1078 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) 1080 For example, a communication flow could be: Node G (RUL) --> Node E 1081 (6LR_1)--> Node B (6LR_i)--> Node A root(6LBR) 1083 6LR_i represents the intermediate routers from the source (RUL) to 1084 the destination (6LBR), 1 <= i <= n, where n is the total number of 1085 routers (6LR) that the packet goes through from the RUL to the 6LBR. 1087 When the packet arrives from the RUL (Node G) to 6LR_1 (Node E), the 1088 6LR_1 will encapsulate the packet in an IPv6-in-IPv6 header with an 1089 RPI. The IPv6-in-IPv6 header is addressed to the root (Node A). The 1090 root removes the header and processes the packet. 1092 The Figure 12 shows the table that summarizes what headers are needed 1093 for this use case where the IPv6-in-IPv6 header is addressed to the 1094 root (Node A). 1096 +-----------+------+--------------+----------------+-----------------+ 1097 | Header | RUL | 6LR_1 | 6LR_i | 6LBR dst | 1098 | | src | | | | 1099 | | node | | | | 1100 +-----------+------+--------------+----------------+-----------------+ 1101 | Added | -- | IP6-IP6 | | -- | 1102 | headers | | RPI | -- | | 1103 +-----------+------+--------------+----------------+-----------------+ 1104 | Modified | -- | -- | RPI | -- | 1105 | headers | | | | | 1106 +-----------+------+--------------+----------------+-----------------+ 1107 | Removed | -- | -- | --- | IP6-IP6 | 1108 | headers | | | | RPI | 1109 +-----------+------+--------------+----------------+-----------------+ 1110 | Untouched | -- | -- | IP6-IP6 | -- | 1111 | headers | | | | | 1112 +-----------+------+--------------+----------------+-----------------+ 1114 Figure 12: SM: Summary of the use of headers from RUL to root. 1116 7.2. SM: Interaction between Leaf and Internet. 1118 In this section is described the communication flow in storing mode 1119 (SM) between, 1121 RAL to Internet 1123 Internet to RAL 1125 RUL to Internet 1127 Internet to RUL 1129 7.2.1. SM: Example of Flow from RAL to Internet 1131 In this case the flow comprises: 1133 RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet 1135 For example, the communication flow could be: Node F (RAL) --> Node D 1136 (6LR_i)--> Node B (6LR_i)--> Node A root(6LBR) --> Internet 1138 6LR_i represents the intermediate routers from the source (RAL) to 1139 the root (6LBR), 1 <= i <= n, where n is the total number of routers 1140 (6LR) that the packet goes through from the RAL to the 6LBR. 1142 RPL information from RFC 6553 may go out to Internet as it will be 1143 ignored by nodes which have not been configured to be RPI aware. No 1144 IPv6-in-IPv6 header is required. 1146 On the other hand, the RAL may insert the RPI encapsulated in a IPv6- 1147 in-IPv6 header to the root. Thus, the root removes the RPI and send 1148 the packet to the Internet. 1150 Note: In this use case, it is used a node as a leaf, but this use 1151 case can be also applicable to any RPL-aware-node type (e.g. 6LR) 1153 The Figure 13 summarizes what headers are needed for this use case 1154 when there is no encapsulation. Note that the RPI is modified by 1155 6LBR to set the SenderRank to zero in case that it is not already 1156 zero. The Figure 14 summarizes what headers are needed when 1157 encapsulation to the root takes place. 1159 +-----------+-----+-------+------+-----------+ 1160 | Header | RAL | 6LR_i | 6LBR | Internet | 1161 | | src | | | dst | 1162 +-----------+-----+-------+------+-----------+ 1163 | Added | RPI | -- | -- | -- | 1164 | headers | | | | | 1165 +-----------+-----+-------+------+-----------+ 1166 | Modified | -- | RPI | RPI | -- | 1167 | headers | | | | | 1168 +-----------+-----+-------+------+-----------+ 1169 | Removed | -- | -- | -- | -- | 1170 | headers | | | | | 1171 +-----------+-----+-------+------+-----------+ 1172 | Untouched | -- | -- | -- | RPI | 1173 | headers | | | | (Ignored) | 1174 +-----------+-----+-------+------+-----------+ 1176 Figure 13: SM: Summary of the use of headers from RAL to Internet 1177 with no encapsulation 1179 +-----------+----------+--------------+--------------+--------------+ 1180 | Header | RAL | 6LR_i | 6LBR | Internet dst | 1181 | | src | | | | 1182 +-----------+----------+--------------+--------------+--------------+ 1183 | Added | IP6-IP6 | -- | -- | -- | 1184 | headers | RPI | | | | 1185 +-----------+----------+--------------+--------------+--------------+ 1186 | Modified | -- | RPI | -- | -- | 1187 | headers | | | | | 1188 +-----------+----------+--------------+--------------+--------------+ 1189 | Removed | -- | -- | IP6-IP6 | -- | 1190 | headers | | | RPI | | 1191 +-----------+----------+--------------+--------------+--------------+ 1192 | Untouched | -- | IP6-IP6 | -- | -- | 1193 | headers | | | | | 1194 +-----------+----------+--------------+--------------+--------------+ 1196 Figure 14: SM: Summary of the use of headers from RAL to Internet 1197 with encapsulation to the root (6LBR). 1199 7.2.2. SM: Example of Flow from Internet to RAL 1201 In this case the flow comprises: 1203 Internet --> root (6LBR) --> 6LR_i --> RAL (6LN) 1205 For example, a communication flow could be: Internet --> Node A 1206 root(6LBR) --> Node B (6LR_1) --> Node D (6LR_n) --> Node F (RAL) 1208 When the packet arrives from Internet to 6LBR the RPI is added in a 1209 outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination address 1210 set to the RAL) and sent to 6LR, which modifies the rank in the RPI. 1211 When the packet arrives at the RAL, the packet is decapsulated, which 1212 removes the RPI before the packet is processed. 1214 The Figure 15 shows the table that summarizes what headers are needed 1215 for this use case. 1217 +-----------+----------+--------------+--------------+--------------+ 1218 | Header | Internet | 6LBR | 6LR_i | RAL dst | 1219 | | src | | | | 1220 +-----------+----------+--------------+--------------+--------------+ 1221 | Added | -- | IP6-IP6(RPI) | -- | -- | 1222 | headers | | | | | 1223 +-----------+----------+--------------+--------------+--------------+ 1224 | Modified | -- | -- | RPI | -- | 1225 | headers | | | | | 1226 +-----------+----------+--------------+--------------+--------------+ 1227 | Removed | -- | -- | -- | IP6-IP6(RPI) | 1228 | headers | | | | | 1229 +-----------+----------+--------------+--------------+--------------+ 1230 | Untouched | -- | -- | -- | -- | 1231 | headers | | | | | 1232 +-----------+----------+--------------+--------------+--------------+ 1234 Figure 15: SM: Summary of the use of headers from Internet to RAL. 1236 7.2.3. SM: Example of Flow from RUL to Internet 1238 In this case the flow comprises: 1240 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet 1242 For example, a communication flow could be: Node G (RUL)--> Node E 1243 (6LR_1)--> Node B (6lR_i) --> Node A root(6LBR) --> Internet 1245 The node 6LR_1 (i=1) will add an IPv6-in-IPv6(RPI) header addressed 1246 to the root such that the root can remove the RPI before passing 1247 upwards. In the intermediate 6LR, the rank in the RPI is modified. 1249 The originating node will ideally leave the IPv6 flow label as zero 1250 so that the packet can be better compressed through the LLN. The 1251 6LBR will set the flow label of the packet to a non-zero value when 1252 sending to the Internet, for details check [RFC6437]. 1254 The Figure 16 shows the table that summarizes what headers are needed 1255 for this use case. 1257 +---------+-------+------------+-------------+-------------+--------+ 1258 | Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet| 1259 | | src | | [i=2,...,n] | | dst | 1260 | | node | | | | | 1261 | | (RUL) | | | | | 1262 +---------+-------+------------+-------------+-------------+--------+ 1263 | Added | -- |IP6-IP6(RPI)| -- | -- | -- | 1264 | headers | | | | | | 1265 +---------+-------+------------+-------------+-------------+--------+ 1266 | Modified| -- | -- | RPI | -- | -- | 1267 | headers | | | | | | 1268 +---------+-------+------------+-------------+-------------+--------+ 1269 | Removed | -- | -- | -- | IP6-IP6(RPI)| -- | 1270 | headers | | | | | | 1271 +---------+-------+------------+-------------+-------------+--------+ 1272 |Untouched| -- | -- | -- | -- | -- | 1273 | headers | | | | | | 1274 +---------+-------+------------+-------------+-------------+--------+ 1276 Figure 16: SM: Summary of the use of headers from RUL to Internet. 1278 7.2.4. SM: Example of Flow from Internet to RUL. 1280 In this case the flow comprises: 1282 Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1284 For example, a communication flow could be: Internet --> Node A 1285 root(6LBR) --> Node B (6LR_i)--> Node E (6LR_n) --> Node G (RUL) 1287 The 6LBR will have to add an RPI within an IPv6-in-IPv6 header. The 1288 IPv6-in-IPv6 is addressed to the 6LR parent of the RUL. 1290 Further details about this are mentioned in 1291 [I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN 1292 acting as a plain host and not being aware of RPL. 1294 The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to 1295 zero in order to aid in compression [RFC8138][RFC6437]. 1297 The Figure 17 shows the table that summarizes what headers are needed 1298 for this use case. 1300 +---------+-------+------------+--------------+-------------+-------+ 1301 | Header |Inter- | 6LBR | 6LR_i | 6LR_n | RUL | 1302 | | net | |[i=1,..,n-1] | | dst | 1303 | | src | | | | | 1304 | | | | | | | 1305 +---------+-------+------------+--------------+-------------+-------+ 1306 | Inserted| -- |IP6-IP6(RPI)| -- | -- | -- | 1307 | headers | | | | | | 1308 +---------+-------+------------+--------------+-------------+-------+ 1309 | Modified| -- | -- | RPI | -- | -- | 1310 | headers | | | | | | 1311 +---------+-------+------------+--------------+-------------+-------+ 1312 | Removed | -- | -- | -- | IP6-IP6(RPI)| -- | 1313 | headers | | | | | | 1314 +---------+-------+------------+--------------+-------------+-------+ 1315 |Untouched| -- | -- | -- | -- | -- | 1316 | headers | | | | | | 1317 +---------+-------+------------+--------------+-------------+-------+ 1319 Figure 17: SM: Summary of the use of headers from Internet to RUL. 1321 7.3. SM: Interaction between Leaf and Leaf 1323 In this section is described the communication flow in storing mode 1324 (SM) between, 1326 RAL to RAL 1328 RAL to RUL 1330 RUL to RAL 1332 RUL to RUL 1334 7.3.1. SM: Example of Flow from RAL to RAL 1336 In [RFC6550] RPL allows a simple one-hop optimization for both 1337 storing and non-storing networks. A node may send a packet destined 1338 to a one-hop neighbor directly to that node. See section 9 in 1339 [RFC6550]. 1341 When the nodes are not directly connected, then in storing mode, the 1342 flow comprises: 1344 RAL src (6LN) --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> RAL 1345 dst (6LN) 1346 For example, a communication flow could be: Node F (RAL src)--> Node 1347 D (6LR_ia)--> Node B (6LR_x) --> Node E (6LR_id) --> Node H (RAL dst) 1349 6LR_ia (Node D) represents the intermediate routers from source to 1350 the common parent (6LR_x) (Node B), 1 <= ia <= n, where n is the 1351 total number of routers (6LR) that the packet goes through from RAL 1352 (Node F) to the common parent 6LR_x (Node B). 1354 6LR_id (Node E) represents the intermediate routers from the common 1355 parent (6LR_x) (Node B) to destination RAL (Node H), 1 <= id <= m, 1356 where m is the total number of routers (6LR) that the packet goes 1357 through from the common parent (6LR_x) to destination RAL (Node H). 1359 It is assumed that the two nodes are in the same RPL domain (that 1360 they share the same DODAG root). At the common parent (Node B), the 1361 direction flag ('O' flag) of the RPI is changed (from decreasing 1362 ranks to increasing ranks). 1364 While the 6LR nodes will update the RPI, no node needs to add or 1365 remove the RPI, so no IPv6-in-IPv6 headers are necessary. 1367 The Figure 18 summarizes what headers are needed for this use case. 1369 +-----------+-----+--------+---------+--------+-----+ 1370 | Header | RAL | 6LR_ia | 6LR_x | 6LR_id | RAL | 1371 | | src | | (common | | dst | 1372 | | | | parent) | | | 1373 +-----------+-----+--------+---------+--------+-----+ 1374 | Added | RPI | -- | -- | -- | -- | 1375 | headers | | | | | | 1376 +-----------+-----+--------+---------+--------+-----+ 1377 | Modified | -- | RPI | RPI | RPI | -- | 1378 | headers | | | | | | 1379 +-----------+-----+--------+---------+--------+-----+ 1380 | Removed | -- | -- | -- | -- | RPI | 1381 | headers | | | | | | 1382 +-----------+-----+--------+---------+--------+-----+ 1383 | Untouched | -- | -- | -- | -- | -- | 1384 | headers | | | | | | 1385 +-----------+-----+--------+---------+--------+-----+ 1387 Figure 18: SM: Summary of the Use of Headers from RAL to RAL 1389 7.3.2. SM: Example of Flow from RAL to RUL 1391 In this case the flow comprises: 1393 RAL src (6LN) --> 6LR_ia --> common parent (6LBR - The root-) --> 1394 6LR_id --> RUL (IPv6 dst node) 1396 For example, a communication flow could be: Node F (RAL)--> Node D 1397 --> Node B--> Node A -->Node B --> Node E --> Node G (RUL) 1399 6LR_ia represents the intermediate routers from source (RAL) to the 1400 common parent (the Root), 1 <= ia <= n, where n is the total number 1401 of routers (6LR) that the packet goes through from RAL to the Root. 1403 6LR_id (Node E) represents the intermediate routers from the Root 1404 (Node B) to destination RUL (Node G). In this case, 1 <= id <= m, 1405 where m is the total number of routers (6LR) that the packet goes 1406 through from the Root down to the destination RUL. 1408 In this case, the packet from the RAL goes to 6LBR because the route 1409 to the RUL is not injected into the RPL-SM. Thus, the RAL inserts an 1410 RPI (RPI1) addressed to the root(6LBR). The root does not remove the 1411 RPI1 (the root cannot remove an RPI if there is no encapsulation). 1412 The root inserts an IPv6-IPv6 encapsulation with an RPI2 and sends it 1413 to the 6LR parent of the RUL, which removes the encapsulation and 1414 RPI2 before passing the packet to the RUL. 1416 The Figure 19 summarizes what headers are needed for this use case. 1418 +----------+-------+-------+---------+---------+---------+---------+ 1419 | Header | RAL |6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL | 1420 | | src | | | | | dst | 1421 | | node | | | | | node | 1422 +----------+-------+-------+---------+---------+---------+---------+ 1423 | Added | | | IP6-IP6 | -- | -- | -- | 1424 | headers | RPI1 | -- | (RPI2) | | | | 1425 | | | | | | | | 1426 +----------+-------+-------+---------+---------+---------+---------+ 1427 | Modified | -- | | -- | | | -- | 1428 | headers | | RPI1 | | RPI2 | -- | | 1429 | | | | | | | | 1430 +----------+-------+-------+---------+---------+---------+---------+ 1431 | Removed | -- | -- | | -- | IP6-IP6 | -- | 1432 | headers | | | -- | | (RPI2) | | 1433 | | | | | | | | 1434 +----------+-------+-------+---------+---------+---------+---------+ 1435 |Untouched | -- | -- | RPI1 | RPI1 | RPI1 | RPI1 | 1436 | headers | | | | | |(Ignored)| 1437 | | | | | | | | 1438 +----------+-------+-------+---------+---------+---------+---------+ 1440 Figure 19: SM: Summary of the Use of Headers from RAL to RUL 1442 7.3.3. SM: Example of Flow from RUL to RAL 1444 In this case the flow comprises: 1446 RUL (IPv6 src node) --> 6LR_ia --> 6LBR --> 6LR_id --> RAL dst (6LN) 1448 For example, a communication flow could be: Node G (RUL)--> Node E 1449 --> Node B --> Node A --> Node B --> Node D --> Node F (RAL) 1451 6LR_ia (Node E) represents the intermediate routers from source (RUL) 1452 (Node G) to the root (Node A). In this case, 1 <= ia <= n, where n 1453 is the total number of routers (6LR) that the packet goes through 1454 from source to the root. 1456 6LR_id represents the intermediate routers from the root (Node A) to 1457 destination RAL (Node F). In this case, 1 <= id <= m, where m is the 1458 total number of routers (6LR) that the packet goes through from the 1459 root to the destination RAL. 1461 The 6LR_1 (Node E) receives the packet from the RUL (Node G) and 1462 inserts the RPI (RPI1) encapsulated in a IPv6-in-IPv6 header to the 1463 root. The root removes the outer header including the RPI (RPI1) and 1464 inserts a new RPI (RPI2) addressed to the destination RAL (Node F). 1466 The Figure 20 shows the table that summarizes what headers are needed 1467 for this use case. 1469 +-----------+------+---------+---------+---------+---------+---------+ 1470 | Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL | 1471 | | src | | | | | dst | 1472 | | node | | | | | node | 1473 +-----------+------+---------+---------+---------+---------+---------+ 1474 | Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- | 1475 | headers | | (RPI1) | | (RPI2) | | | 1476 | | | | | | | | 1477 +-----------+------+---------+---------+---------+---------+---------+ 1478 | Modified | -- | | | -- | | -- | 1479 | headers | | -- | RPI1 | | RPI2 | | 1480 | | | | | | | | 1481 +-----------+------+---------+---------+---------+---------+---------+ 1482 | Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 | 1483 | headers | | -- | | (RPI1) | | (RPI2) | 1484 | | | | | | | | 1485 +-----------+------+---------+---------+---------+---------+---------+ 1486 | Untouched | -- | -- | -- | -- | -- | -- | 1487 | headers | | | | | | | 1488 +-----------+------+---------+---------+---------+---------+---------+ 1490 Figure 20: SM: Summary of the use of headers from RUL to RAL. 1492 7.3.4. SM: Example of Flow from RUL to RUL 1494 In this case the flow comprises: 1496 RUL (IPv6 src node)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id --> RUL 1497 (IPv6 dst node) 1499 For example, a communication flow could be: Node G (RUL src)--> Node 1500 E --> Node B --> Node A (root) --> Node C --> Node J (RUL dst) 1502 Internal nodes 6LR_ia (e.g: Node E or Node B) is the intermediate 1503 router from the RUL source (Node G) to the root (6LBR) (Node A). In 1504 this case, 1 <= ia <= n, where n is the total number of routers (6LR) 1505 that the packet goes through from the RUL to the root. 6LR_1 refers 1506 when ia=1. 1508 6LR_id (Node C) represents the intermediate routers from the root 1509 (Node A) to the destination RUL dst node (Node J). In this case, 1 1510 <= id <= m, where m is the total number of routers (6LR) that the 1511 packet goes through from the root to destination RUL. 1513 The 6LR_1 (Node E) receives the packet from the RUL (Node G) and 1514 inserts the RPI (RPI), encapsulated in an IPv6-in-IPv6 header 1515 directed to the root. The root removes the outer header including 1516 the RPI (RPI1) and inserts a new RPI (RPI2) addressed to the 6LR 1517 father of the RUL. 1519 The Figure 21 shows the table that summarizes what headers are needed 1520 for this use case. 1522 +---------+----+-------------+--------+---------+--------+-------+---+ 1523 | Header |RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id |6LR_n |RUL| 1524 | |src | | | | | |dst| 1525 | | | | | | | | | 1526 +---------+----+-------------+--------+---------+--------+-------+---+ 1527 | Added | -- |IP6-IP6(RPI1)| -- | IP6-IP6 | -- | -- | --| 1528 | Headers | | | | (RPI2) | | | | 1529 +---------+----+-------------+--------+---------+--------+-------+---+ 1530 |Modified | -- | -- | | -- | | -- | --| 1531 |headers | | | RPI1 | | RPI2 | | | 1532 +---------+----+-------------+--------+---------+--------+-------+---+ 1533 | Removed | -- | -- | -- | IP6-IP6 | -- |IP6-IP6| --| 1534 | headers | | | | (RPI1) | | (RPI2)| | 1535 +---------+----+-------------+--------+---------+--------+-------+---+ 1536 |Untouched| -- | -- | -- | -- | -- | -- | --| 1537 | headers | | | | | | | | 1538 +---------+----+-------------+--------+---------+--------+-------+---+ 1540 Figure 21: SM: Summary of the use of headers from RUL to RUL 1542 8. Non Storing mode 1544 In Non Storing Mode (Non-SM) (fully source routed), the 6LBR (DODAG 1545 root) has complete knowledge about the connectivity of all DODAG 1546 nodes, and all traffic flows through the root node. Thus, there is 1547 no need for all nodes to know about the existence of RPL-unaware 1548 nodes. Only the 6LBR needs to act if compensation is necessary for 1549 not-RPL aware receivers. 1551 The table (Figure 22) summarizes what headers are needed in the 1552 following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6 1553 header are to be inserted. The last column depicts the target 1554 destination of the IPv6-in-IPv6 header: 6LN (indicated by "RAL"), 6LR 1555 (parent of a RUL) or the root. In cases where no IPv6-in-IPv6 header 1556 is needed, the column indicates "No". There is no expectation on RPL 1557 that RPI can be omitted, because it is needed for routing, quality of 1558 service and compression. This specification expects that an RPI is 1559 always present. The term "may(up)" means that the IPv6-in-IPv6 1560 header may be necessary in the upwards direction. The term 1561 "must(up)" means that the IPv6-in-IPv6 header must be present in the 1562 upwards direction. The term "must(down)" means that the IPv6-in-IPv6 1563 header must be present in the downward direction. 1565 The leaf can be a router 6LR or a host, both indicated as 6LN 1566 (Figure 6). In the table (Figure 22) the (1) indicates a 6tisch case 1567 [RFC8180], where the RPI may still be needed for the RPLInstanceID to 1568 be available for priority/channel selection at each hop. 1570 +--- ------------+-------------+-----+-----+--------------+----------+ 1571 | Interaction | Use Case | RPI | RH3 | IPv6-in-IPv6 | IP-in-IP | 1572 | between | | | | | dst | 1573 +----------------+-------------+-----+-----+--------------+----------+ 1574 | | RAL to root | Yes | No | No | No | 1575 | +-------------+-----+-----+--------------+----------+ 1576 | Leaf - Root | root to RAL | Yes | Yes | No | No | 1577 | +-------------+-----+-----+--------------+----------+ 1578 | | root to RUL | Yes | Yes | No | 6LR | 1579 | | | (1) | | | | 1580 | +-------------+-----+-----+--------------+----------+ 1581 | | RUL to root | Yes | No | must | root | 1582 +----------------+-------------+-----+-----+--------------+----------+ 1583 | | RAL to Int | Yes | No | may(up) | root | 1584 | +-------------+-----+-----+--------------+----------+ 1585 |Leaf - Internet | Int to RAL | Yes | Yes | must | RAL | 1586 | +-------------+-----+-----+--------------+----------+ 1587 | | RUL to Int | Yes | No | must | root | 1588 | +-------------+-----+-----+--------------+----------+ 1589 | | Int to RUL | Yes | Yes | must | 6LR | 1590 +----------------+-------------+-----+-----+--------------+----------+ 1591 | | RAL to RAL | Yes | Yes | may(up) | root | 1592 | | | | +--------------+----------+ 1593 | | | | | must(down) | RAL | 1594 | Leaf - Leaf +-------------+-----+-----+--------------+----------+ 1595 | | RAL to RUL | Yes | Yes | may(up) | root | 1596 | | | | +--------------+----------+ 1597 | | | | | must(down) | 6LR | 1598 | +-------------+-----+-----+--------------+----------+ 1599 | | RUL to RAL | Yes | Yes | must(up) | root | 1600 | | | | +--------------+----------+ 1601 | | | | | must(down) | RAL | 1602 | +-------------+-----+-----+--------------+----------+ 1603 | | RUL to RUL | Yes | Yes | must(up) | root | 1604 | | | | +--------------+----------+ 1605 | | | | | must(down) | 6LR | 1606 +----------------+-------------+-----+-----+--------------+----------+ 1608 Figure 22: Table that shows headers needed in Non-Storing mode: RPI, 1609 RH3, IPv6-in-IPv6 encapsulation. 1611 8.1. Non-Storing Mode: Interaction between Leaf and Root 1613 In this section is described the communication flow in Non Storing 1614 Mode (Non-SM) between, 1616 RAL to root 1618 root to RAL 1620 RUL to root 1622 root to RUL 1624 8.1.1. Non-SM: Example of Flow from RAL to root 1626 In non-storing mode the leaf node uses default routing to send 1627 traffic to the root. The RPI must be included since it contains the 1628 rank information, which is used to avoid/detect loops. 1630 RAL (6LN) --> 6LR_i --> root(6LBR) 1632 For example, a communication flow could be: Node F --> Node D --> 1633 Node B --> Node A (root) 1635 6LR_i represents the intermediate routers from source to destination. 1636 In this case, 1 <= i <= n, where n is the total number of routers 1637 (6LR) that the packet goes through from source (RAL) to destination 1638 (6LBR). 1640 This situation is the same case as storing mode. 1642 The Figure 23 summarizes what headers are needed for this use case. 1644 +-----------+-----+-------+------+ 1645 | Header | RAL | 6LR_i | 6LBR | 1646 | | src | | dst | 1647 +-----------+-----+-------+------+ 1648 | Added | RPI | -- | -- | 1649 | headers | | | | 1650 +-----------+-----+-------+------+ 1651 | Modified | -- | RPI | -- | 1652 | headers | | | | 1653 +-----------+-----+-------+------+ 1654 | Removed | -- | -- | RPI | 1655 | headers | | | | 1656 +-----------+-----+-------+------+ 1657 | Untouched | -- | -- | -- | 1658 | headers | | | | 1659 +-----------+-----+-------+------+ 1661 Figure 23: Non-SM: Summary of the use of headers from RAL to root 1663 8.1.2. Non-SM: Example of Flow from root to RAL 1665 In this case the flow comprises: 1667 root (6LBR) --> 6LR_i --> RAL (6LN) 1669 For example, a communication flow could be: Node A (root) --> Node B 1670 --> Node D --> Node F 1672 6LR_i represents the intermediate routers from source to destination. 1673 In this case, 1 <= i <= n, where n is the total number of routers 1674 (6LR) that the packet goes through from source (6LBR) to destination 1675 (RAL). 1677 The 6LBR inserts an RH3, and an RPI. No IPv6-in-IPv6 header is 1678 necessary as the traffic originates with a RPL aware node, the 6LBR. 1679 The destination is known to be RPL-aware because the root knows the 1680 whole topology in non-storing mode. 1682 The Figure 24 summarizes what headers are needed for this use case. 1684 +-----------+----------+----------+----------+ 1685 | Header | 6LBR | 6LR_i | RAL | 1686 | | src | | dst | 1687 +-----------+----------+----------+----------+ 1688 | Added | RPI, RH3 | -- | -- | 1689 | headers | | | | 1690 +-----------+----------+----------+----------+ 1691 | Modified | -- | RPI, RH3 | -- | 1692 | headers | | | | 1693 +-----------+----------+----------+----------+ 1694 | Removed | -- | -- | RPI, RH3 | 1695 | headers | | | | 1696 +-----------+----------+----------+----------+ 1697 | Untouched | -- | -- | -- | 1698 | headers | | | | 1699 +-----------+----------+----------+----------+ 1701 Figure 24: Non-SM: Summary of the use of headers from root to RAL 1703 8.1.3. Non-SM: Example of Flow from root to RUL 1705 In this case the flow comprises: 1707 root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1709 For example, a communication flow could be: Node A (root) --> Node B 1710 --> Node E --> Node G (RUL) 1712 6LR_i represents the intermediate routers from source to destination. 1713 In this case, 1 <= i <= n, where n is the total number of routers 1714 (6LR) that the packet goes through from source (6LBR) to destination 1715 (RUL). 1717 In the 6LBR, the RH3 is added; it is then modified at each 1718 intermediate 6LR (6LR_1 and so on), and it is fully consumed in the 1719 last 6LR (6LR_n) but is left in place. When the RPI is added, the 1720 RUL, which does not understand the RPI, will ignore it (per 1721 [RFC8200]); thus, encapsulation is not necessary. 1723 The Figure 25 depicts the table that summarizes what headers are 1724 needed for this use case. 1726 +-----------+----------+--------------+----------------+----------+ 1727 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 1728 | | src | i=(1,..,n-1) | | dst | 1729 | | | | | | 1730 +-----------+----------+--------------+----------------+----------+ 1731 | Added | RPI, RH3 | -- | -- | -- | 1732 | headers | | | | | 1733 +-----------+----------+--------------+----------------+----------+ 1734 | Modified | -- | RPI, RH3 | RPI, | -- | 1735 | headers | | | RH3(consumed) | | 1736 +-----------+----------+--------------+----------------+----------+ 1737 | Removed | -- | -- | -- | -- | 1738 | headers | | | | | 1739 +-----------+----------+--------------+----------------+----------+ 1740 | Untouched | -- | -- | -- | RPI, RH3 | 1741 | headers | | | | (both | 1742 | | | | | ignored) | 1743 +-----------+----------+--------------+----------------+----------+ 1745 Figure 25: Non-SM: Summary of the use of headers from root to RUL 1747 8.1.4. Non-SM: Example of Flow from RUL to root 1749 In this case the flow comprises: 1751 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) dst 1753 For example, a communication flow could be: Node G --> Node E --> 1754 Node B --> Node A (root) 1756 6LR_i represents the intermediate routers from source to destination. 1757 In this case, 1 <= i <= n, where n is the total number of routers 1758 (6LR) that the packet goes through from source (RUL) to destination 1759 (6LBR). For example, 6LR_1 (i=1) is the router that receives the 1760 packets from the RUL. 1762 In this case, the RPI is added by the first 6LR (6LR_1) (Node E), 1763 encapsulated in an IPv6-in-IPv6 header, and modified in the 1764 subsequent 6LRs in the flow. The RPI and the entire packet are 1765 consumed by the root. 1767 The Figure 26 shows the table that summarizes what headers are needed 1768 for this use case. 1770 +---------+----+-----------------+-----------------+-----------------+ 1771 | |RUL | | | | 1772 | Header |src | 6LR_1 | 6LR_i | 6LBR dst | 1773 | |node| | | | 1774 +---------+----+-----------------+-----------------+-----------------+ 1775 | Added | -- |IPv6-in-IPv6(RPI)| -- | -- | 1776 | headers | | | | | 1777 +---------+----+-----------------+-----------------+-----------------+ 1778 | Modified| -- | -- | RPI | -- | 1779 | headers | | | | | 1780 +---------+----+-----------------+-----------------+-----------------+ 1781 | Removed | -- | -- | -- |IPv6-in-IPv6(RPI)| 1782 | headers | | | | | 1783 +---------+----+-----------------+-----------------+-----------------+ 1784 |Untouched| -- | -- | -- | -- | 1785 | headers | | | | | 1786 +---------+----+-----------------+-----------------+-----------------+ 1788 Figure 26: Non-SM: Summary of the use of headers from RUL to root 1790 8.2. Non-Storing Mode: Interaction between Leaf and Internet 1792 This section will describe the communication flow in Non Storing Mode 1793 (Non-SM) between: 1795 RAL to Internet 1797 Internet to RAL 1799 RUL to Internet 1801 Internet to RUL 1803 8.2.1. Non-SM: Example of Flow from RAL to Internet 1805 In this case the flow comprises: 1807 RAL (6LN) src --> 6LR_i --> root (6LBR) --> Internet dst 1809 For example, a communication flow could be: Node F (RAL) --> Node D 1810 --> Node B --> Node A --> Internet. Having the RAL information about 1811 the RPL domain, the packet may be encapsulated to the root when the 1812 destination is not in the RPL domain of the RAL. 1814 6LR_i represents the intermediate routers from source to destination, 1815 1 <= i <= n, where n is the total number of routers (6LR) that the 1816 packet goes through from source (RAL) to 6LBR. 1818 In this case, the encapsulation from the RAL to the root is optional. 1819 The simplest case is when the RPI gets to the Internet (as the 1820 Figure 27 shows it), knowing that the Internet is going to ignore it. 1822 The IPv6 flow label should be set to zero to aid in compression 1823 [RFC8138], and the 6LBR will set it to a non-zero value when sending 1824 towards the Internet [RFC6437]. 1826 The Figure 27 summarizes what headers are needed for this use case 1827 when no encapsulation is used. The Figure 28 summarizes what headers 1828 are needed for this use case when encapsulation to the root is used. 1830 +-----------+-----+-------+------+-----------+ 1831 | Header | RAL | 6LR_i | 6LBR | Internet | 1832 | | src | | | dst | 1833 +-----------+-----+-------+------+-----------+ 1834 | Added | RPI | -- | -- | -- | 1835 | headers | | | | | 1836 +-----------+-----+-------+------+-----------+ 1837 | Modified | -- | RPI | RPI | -- | 1838 | headers | | | | | 1839 +-----------+-----+-------+------+-----------+ 1840 | Removed | -- | -- | -- | -- | 1841 | headers | | | | | 1842 +-----------+-----+-------+------+-----------+ 1843 | Untouched | -- | -- | -- | RPI | 1844 | headers | | | | (Ignored) | 1845 +-----------+-----+-------+------+-----------+ 1847 Figure 27: Non-SM: Summary of the use of headers from RAL to Internet 1848 with no encapsulation 1850 +-----------+--------------+--------------+--------------+----------+ 1851 | Header | RAL | 6LR_i | 6LBR | Internet | 1852 | | src | | | dst | 1853 +-----------+--------------+--------------+--------------+----------+ 1854 | Added | IPv6-in-IPv6 | -- | -- | -- | 1855 | headers | (RPI) | | | | 1856 +-----------+--------------+--------------+--------------+----------+ 1857 | Modified | -- | | -- | -- | 1858 | headers | | RPI | | | 1859 +-----------+--------------+--------------+--------------+----------+ 1860 | Removed | -- | -- | IPv6-in-IPv6 | -- | 1861 | headers | | | (RPI) | | 1862 +-----------+--------------+--------------+--------------+----------+ 1863 | Untouched | -- | -- | -- | -- | 1864 | headers | | | | | 1865 +-----------+--------------+--------------+--------------+----------+ 1867 Figure 28: Non-SM: Summary of the use of headers from RAL to Internet 1868 with encapsulation to the root 1870 8.2.2. Non-SM: Example of Flow from Internet to RAL 1872 In this case the flow comprises: 1874 Internet --> root (6LBR) --> 6LR_i --> RAL dst (6LN) 1876 For example, a communication flow could be: Internet --> Node A 1877 (root) --> Node B --> Node D --> Node F (RAL) 1879 6LR_i represents the intermediate routers from source to destination, 1880 1 <= i <= n, where n is the total number of routers (6LR) that the 1881 packet goes through from 6LBR to destination (RAL). 1883 The 6LBR must add an RH3 header. As the 6LBR will know the path and 1884 address of the target node, it can address the IPv6-in-IPv6 header to 1885 that node. The 6LBR will zero the flow label upon entry in order to 1886 aid compression [RFC8138]. 1888 The Figure 29 summarizes what headers are needed for this use case. 1890 +-----------+----------+--------------+--------------+--------------+ 1891 | Header | Internet | 6LBR | 6LR_i | RAL | 1892 | | src | | | dst | 1893 +-----------+----------+--------------+--------------+--------------+ 1894 | Added | -- | IPv6-in-IPv6 | -- | -- | 1895 | headers | | (RH3, RPI) | | | 1896 +-----------+----------+--------------+--------------+--------------+ 1897 | Modified | -- | -- | IPv6-in-IPv6 | -- | 1898 | headers | | | (RH3, RPI) | | 1899 +-----------+----------+--------------+--------------+--------------+ 1900 | Removed | -- | -- | -- | IPv6-in-IPv6 | 1901 | headers | | | | (RH3, RPI) | 1902 +-----------+----------+--------------+--------------+--------------+ 1903 | Untouched | -- | -- | -- | -- | 1904 | headers | | | | | 1905 +-----------+----------+--------------+--------------+--------------+ 1907 Figure 29: Non-SM: Summary of the use of headers from Internet to RAL 1909 8.2.3. Non-SM: Example of Flow from RUL to Internet 1911 In this case the flow comprises: 1913 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet 1914 dst 1916 For example, a communication flow could be: Node G --> Node E --> 1917 Node B --> Node A --> Internet 1919 6LR_i represents the intermediate routers from source to destination, 1920 1 <= i <= n, where n is the total number of routers (6LRs) that the 1921 packet goes through from the source (RUL) to the 6LBR, e.g., 6LR_1 1922 (i=1). 1924 In this case the flow label is recommended to be zero in the RUL. As 1925 the RUL parent adds RPL headers in the RUL packet, the first 6LR 1926 (6LR_1) will add an RPI inside a new IPv6-in-IPv6 header. The IPv6- 1927 in-IPv6 header will be addressed to the root. This case is identical 1928 to the storing-mode case (see Section 7.2.3). 1930 The Figure 30 shows the table that summarizes what headers are needed 1931 for this use case. 1933 +---------+----+-------------+--------------+--------------+--------+ 1934 | Header |RUL | 6LR_1 | 6LR_i | 6LBR |Internet| 1935 | |src | | [i=2,..,n] | | dst | 1936 | |node| | | | | 1937 +---------+----+-------------+--------------+--------------+--------+ 1938 | Added | -- |IP6-IP6(RPI) | -- | -- | -- | 1939 | headers | | | | | | 1940 +---------+----+-------------+--------------+--------------+--------+ 1941 | Modified| -- | -- | RPI | -- | -- | 1942 | headers | | | | | | 1943 +---------+----+-------------+--------------+--------------+--------+ 1944 | Removed | -- | -- | -- | IP6-IP6(RPI) | -- | 1945 | headers | | | | | | 1946 +---------+----+-------------+--------------+--------------+--------+ 1947 |Untouched| -- | -- | -- | -- | -- | 1948 | headers | | | | | | 1949 +---------+----+-------------+--------------+--------------+--------+ 1951 Figure 30: Non-SM: Summary of the use of headers from RUL to Internet 1953 8.2.4. Non-SM: Example of Flow from Internet to RUL 1955 In this case the flow comprises: 1957 Internet src --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1959 For example, a communication flow could be: Internet --> Node A 1960 (root) --> Node B --> Node E --> Node G 1962 6LR_i represents the intermediate routers from source to destination, 1963 1 <= i <= n, where n is the total number of routers (6LR) that the 1964 packet goes through from 6LBR to RUL. 1966 The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The 1967 6LBR will know the path, and will recognize that the final node is 1968 not a RPL capable node as it will have received the connectivity DAO 1969 from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6 1970 header destination be the last 6LR. The 6LBR will set to zero the 1971 flow label upon entry in order to aid compression [RFC8138]. 1973 The Figure 31 shows the table that summarizes what headers are needed 1974 for this use case. 1976 +----------+--------+------------------+-----------+-----------+-----+ 1977 | Header |Internet| 6LBR | 6LR_i | 6LR_n | RUL | 1978 | | src | | | | dst | 1979 +----------+--------+------------------+-----------+-----------+-----+ 1980 | Added | -- | IP6-IP6(RH3,RPI) | -- | -- | -- | 1981 | headers | | | | | | 1982 +----------+--------+------------------+-----------+-----------+-----+ 1983 | Modified | -- | -- | IP6-IP6 | -- | -- | 1984 | headers | | | (RH3,RPI) | | | 1985 +----------+--------+------------------+-----------+-----------+-----+ 1986 | Removed | -- | -- | -- | IP6-IP6 | -- | 1987 | headers | | | | (RH3,RPI) | | 1988 +----------+--------+------------------+-----------+-----------+-----+ 1989 |Untouched | -- | -- | -- | -- | -- | 1990 | headers | | | | | | 1991 +----------+--------+------------------+-----------+-----------+-----+ 1993 Figure 31: Non-SM: Summary of the use of headers from Internet to 1994 RUL. 1996 8.3. Non-SM: Interaction between leaves 1998 In this section is described the communication flow in Non Storing 1999 Mode (Non-SM) between, 2001 RAL to RAL 2003 RAL to RUL 2005 RUL to RAL 2007 RUL to RUL 2009 8.3.1. Non-SM: Example of Flow from RAL to RAL 2011 In this case the flow comprises: 2013 RAL src --> 6LR_ia --> root (6LBR) --> 6LR_id --> RAL dst 2015 For example, a communication flow could be: Node F (RAL src)--> Node 2016 D --> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL 2017 dst) 2019 6LR_ia represents the intermediate routers from source to the root, 1 2020 <= ia <= n, where n is the total number of routers (6LR) that the 2021 packet goes through from RAL to the root. 2023 6LR_id represents the intermediate routers from the root to the 2024 destination, 1 <= id <= m, where m is the total number of the 2025 intermediate routers (6LR). 2027 This case involves only nodes in same RPL domain. The originating 2028 node will add an RPI to the original packet, and send the packet 2029 upwards. 2031 The originating node may put the RPI (RPI1) into an IPv6-in-IPv6 2032 header addressed to the root, so that the 6LBR can remove that 2033 header. If it does not, then the RPI1 is forwarded down from the 2034 root in the inner header to no avail. 2036 The 6LBR will need to insert an RH3 header, which requires that it 2037 add an IPv6-in-IPv6 header. It removes the RPI(RPI1), as it was 2038 contained in an IPv6-in-IPv6 header addressed to it. Otherwise, 2039 there may be an RPI buried inside the inner IP header, which should 2040 get ignored. The root inserts an RPI (RPI2) alongside the RH3. 2042 Networks that use the RPL P2P extension [RFC6997] are essentially 2043 non-storing DODAGs and fall into this scenario or scenario 2044 Section 8.1.2, with the originating node acting as 6LBR. 2046 The Figure 32 shows the table that summarizes what headers are needed 2047 for this use case when encapsulation to the root takes place. 2049 The Figure 33 shows the table that summarizes what headers are needed 2050 for this use case when there is no encapsulation to the root. Note 2051 that in the Modified headers row, going up in each 6LR_ia only the 2052 RPI1 is changed. Going down, in each 6LR_id the IPv6 header is 2053 swapped with the RH3 so both are changed alongside with the RPI2. 2055 +---------+-------+----------+------------+----------+------------+ 2056 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL | 2057 | | src | | | | dst | 2058 +---------+-------+----------+------------+----------+------------+ 2059 | Added |IP6-IP6| | IP6-IP6 | -- | -- | 2060 | headers |(RPI1) | -- |(RH3-> RAL, | | | 2061 | | | | RPI2) | | | 2062 +---------+-------+----------+------------+----------+------------+ 2063 | Modified| -- | | -- | IP6-IP6 | -- | 2064 | headers | | RPI1 | |(RH3,RPI2)| | 2065 +---------+-------+----------+------------+----------+------------+ 2066 | Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | 2067 | headers | | | (RPI1) | | (RH3, | 2068 | | | | | | RPI2) | 2069 +---------+-------+----------+------------+----------+------------+ 2070 |Untouched| -- | -- | -- | -- | -- | 2071 | headers | | | | | | 2072 +---------+-------+----------+------------+----------+------------+ 2074 Figure 32: Non-SM: Summary of the Use of Headers from RAL to RAL with 2075 encapsulation to the root. 2077 +-----------+------+--------+---------+---------+---------+ 2078 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL | 2079 +-----------+------+--------+---------+---------+---------+ 2080 | Inserted | RPI1 | -- | IP6-IP6 | -- | -- | 2081 | headers | | | (RH3, | | | 2082 | | | | RPI2) | | | 2083 +-----------+------+--------+---------+---------+---------+ 2084 | Modified | -- | RPI1 | -- | IP6-IP6 | -- | 2085 | headers | | | | (RH3, | | 2086 | | | | | RPI2) | | 2087 +-----------+------+--------+---------+---------+---------+ 2088 | Removed | -- | -- | -- | -- | IP6-IP6 | 2089 | headers | | | | | (RH3, | 2090 | | | | | | RPI2) | 2091 | | | | | | | 2092 +-----------+------+--------+---------+---------+---------+ 2093 | Untouched | -- | -- | RPI1 | RPI1 | RPI1 | 2094 | headers | | | | |(Ignored)| 2095 +-----------+------+--------+---------+---------+---------+ 2097 Figure 33: Non-SM: Summary of the Use of Headers from RAL to RAL 2098 without encapsulation to the root. 2100 8.3.2. Non-SM: Example of Flow from RAL to RUL 2102 In this case the flow comprises: 2104 RAL --> 6LR_ia --> root (6LBR) --> 6LR_id --> RUL (IPv6 dst node) 2106 For example, a communication flow could be: Node F (RAL) --> Node D 2107 --> Node B --> Node A (root) --> Node B --> Node E --> Node G (RUL) 2109 6LR_ia represents the intermediate routers from source to the root, 1 2110 <= ia <= n, where n is the total number of intermediate routers (6LR) 2112 6LR_id represents the intermediate routers from the root to the 2113 destination, 1 <= id <= m, where m is the total number of the 2114 intermediate routers (6LRs). 2116 As in the previous case, the RAL (6LN) may insert an RPI (RPI1) 2117 header which must be in an IPv6-in-IPv6 header addressed to the root 2118 so that the 6LBR can remove this RPI. The 6LBR will then insert an 2119 RH3 inside a new IPv6-in-IPv6 header addressed to the last 6LR_id 2120 (6LR_id = m) alongside the insertion of RPI2. 2122 If the originating node does not put the RPI (RPI1) into an IPv6-in- 2123 IPv6 header addressed to the root. Then, the RPI1 is forwarded down 2124 from the root in the inner header to no avail. 2126 The Figure 34 shows the table that summarizes what headers are needed 2127 for this use case when encapsulation to the root takes place. The 2128 Figure 35 shows the table that summarizes what headers are needed for 2129 this use case when no encapsulation to the root takes place. 2131 +-----------+---------+---------+---------+---------+---------+------+ 2132 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL | 2133 | | src | | | | | dst | 2134 | | node | | | | | node | 2135 +-----------+---------+---------+---------+---------+---------+------+ 2136 | Added | IP6-IP6 | | IP6-IP6 | -- | -- | -- | 2137 | headers | (RPI1) | -- | (RH3, | | | | 2138 | | | | RPI2) | | | | 2139 +-----------+---------+---------+---------+---------+---------+------+ 2140 | Modified | -- | | -- | IP6-IP6 | | -- | 2141 | headers | | RPI1 | | (RH3, | -- | | 2142 | | | | | RPI2) | | | 2143 +-----------+---------+---------+---------+---------+---------+------+ 2144 | Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- | 2145 | headers | | | (RPI1) | | (RH3, | | 2146 | | | | | | RPI2) | | 2147 +-----------+---------+---------+---------+---------+---------+------+ 2148 | Untouched | -- | -- | -- | -- | -- | -- | 2149 | headers | | | | | | | 2150 +-----------+---------+---------+---------+---------+---------+------+ 2152 Figure 34: Non-SM: Summary of the use of headers from RAL to RUL with 2153 encapsulation to the root. 2155 +-----------+------+--------+---------+---------+---------+---------+ 2156 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_n | RUL | 2157 | | src | | | | | dst | 2158 | | node | | | | | node | 2159 +-----------+------+--------+---------+---------+---------+---------+ 2160 | Inserted | RPI1 | -- | IP6-IP6 | -- | -- | -- | 2161 | headers | | | (RH3, | | | | 2162 | | | | RPI2) | | | | 2163 +-----------+------+--------+---------+---------+---------+---------+ 2164 | Modified | -- | RPI1 | -- | IP6-IP6 | -- | -- | 2165 | headers | | | | (RH3, | | | 2166 | | | | | RPI2) | | | 2167 +-----------+------+--------+---------+---------+---------+---------+ 2168 | Removed | -- | -- | -- | -- | IP6-IP6 | -- | 2169 | headers | | | | | (RH3, | | 2170 | | | | | | RPI2) | | 2171 +-----------+------+--------+---------+---------+---------+---------+ 2172 | Untouched | -- | -- | RPI1 | RPI1 | RPI1 | RPI1 | 2173 | headers | | | | | |(Ignored)| 2174 +-----------+------+--------+---------+---------+---------+---------+ 2176 Figure 35: Non-SM: Summary of the use of headers from RAL to RUL 2177 without encapsulation to the root. 2179 8.3.3. Non-SM: Example of Flow from RUL to RAL 2181 In this case the flow comprises: 2183 RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id 2184 --> RAL dst (6LN) 2186 For example, a communication flow could be: Node G (RUL)--> Node E 2187 --> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL) 2189 6LR_ia represents the intermediate routers from source to the root, 1 2190 <= ia <= n, where n is the total number of intermediate routers (6LR) 2192 6LR_id represents the intermediate routers from the root to the 2193 destination, 1 <= id <= m, where m is the total number of the 2194 intermediate routers (6LR). 2196 In this scenario the RPI (RPI1) is added by the first 6LR (6LR_1) 2197 inside an IPv6-in-IPv6 header addressed to the root. The 6LBR will 2198 remove this RPI, and add its own IPv6-in-IPv6 header containing an 2199 RH3 header and an RPI (RPI2). 2201 The Figure 36 shows the table that summarizes what headers are needed 2202 for this use case. 2204 +----------+------+---------+---------+---------+---------+---------+ 2205 | Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL | 2206 | | src | | | | | dst | 2207 | | node | | | | | node | 2208 +----------+------+---------+---------+---------+---------+---------+ 2209 | Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- | 2210 | headers | | (RPI1) | | (RH3, | | | 2211 | | | | | RPI2) | | | 2212 +----------+------+---------+---------+---------+---------+---------+ 2213 | Modified | -- | | | -- | IP6-IP6 | -- | 2214 | headers | | -- | RPI1 | | (RH3, | | 2215 | | | | | | RPI2) | | 2216 +----------+------+---------+---------+---------+---------+---------+ 2217 | Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 | 2218 | headers | | -- | | (RPI1) | | (RH3, | 2219 | | | | | | | RPI2) | 2220 +----------+------+---------+---------+---------+---------+---------+ 2221 |Untouched | -- | -- | -- | -- | -- | -- | 2222 | headers | | | | | | | 2223 +----------+------+---------+---------+---------+---------+---------+ 2225 Figure 36: Non-SM: Summary of the use of headers from RUL to RAL. 2227 8.3.4. Non-SM: Example of Flow from RUL to RUL 2229 In this case the flow comprises: 2231 RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id 2232 --> RUL (IPv6 dst node) 2234 For example, a communication flow could be: Node G --> Node E --> 2235 Node B --> Node A (root) --> Node C --> Node J 2237 6LR_ia represents the intermediate routers from source to the root, 1 2238 <= ia <= n, where n is the total number of intermediate routers (6LR) 2240 6LR_id represents the intermediate routers from the root to the 2241 destination, 1 <= id <= m, where m is the total number of the 2242 intermediate routers (6LR). 2244 This scenario is the combination of the previous two cases. 2246 The Figure 37 shows the table that summarizes what headers are needed 2247 for this use case. 2249 +---------+------+-------+-------+---------+-------+---------+------+ 2250 | Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | RUL | 2251 | | src | | | | | | dst | 2252 | | node | | | | | | node | 2253 +---------+------+-------+-------+---------+-------+---------+------+ 2254 | Added | -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- | 2255 | headers | | (RPI1)| | (RH3, | | | | 2256 | | | | | RPI2) | | | | 2257 +---------+------+-------+-------+---------+-------+---------+------+ 2258 | Modified| -- | -- | | -- |IP6-IP6| -- | -- | 2259 | headers | | | RPI1 | | (RH3, | | | 2260 | | | | | | RPI2)| | | 2261 +---------+------+-------+-------+---------+-------+---------+------+ 2262 | Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- | 2263 | headers | | | | (RPI1) | | (RH3, | | 2264 | | | | | | | RPI2) | | 2265 +---------+------+-------+-------+---------+-------+---------+------+ 2266 |Untouched| -- | -- | -- | -- | -- | -- | -- | 2267 | headers | | | | | | | | 2268 +---------+------+-------+-------+---------+-------+---------+------+ 2270 Figure 37: Non-SM: Summary of the use of headers from RUL to RUL 2272 9. Operational Considerations of supporting RUL-leaves 2274 Roughly half of the situations described in this document involve 2275 leaf ("host") nodes that do not speak RPL. These nodes fall into two 2276 further categories: ones that drop a packet that have RPI or RH3 2277 headers, and ones that continue to process a packet that has RPI and/ 2278 or RH3 headers. 2280 [RFC8200] provides for new rules that suggest that nodes that have 2281 not been configured (explicitly) to examine Hop-by-Hop headers, 2282 should ignore those headers, and continue processing the packet. 2283 Despite this, and despite the switch from 0x63 to 0x23, there may be 2284 nodes that are pre-RFC8200, or simply intolerant. Those nodes will 2285 drop packets that continue to have RPL artifacts in them. In 2286 general, such nodes can not be easily supported in RPL LLNs. 2288 There are some specific cases where it is possible to remove the RPL 2289 artifacts prior to forwarding the packet to the leaf host. The 2290 critical thing is that the artifacts have been inserted by the RPL 2291 root inside an IPv6-in-IPv6 header, and that the header has been 2292 addressed to the 6LR immediately prior to the leaf node. In that 2293 case, in the process of removing the IPv6-in-IPv6 header, the 2294 artifacts can also be removed. 2296 The above case occurs whenever traffic originates from the outside 2297 the LLN (the "Internet" cases above), and non-storing mode is used. 2298 In non-storing mode, the RPL root knows the exact topology (as it 2299 must create the RH3 header) and therefore knows which 6LR is prior to 2300 the leaf. For example, in Figure 6, Node E is the 6LR prior to leaf 2301 Node G, or Node C is the 6LR prior to leaf Node J. 2303 Traffic originating from the RPL root (such as when the data 2304 collection system is co-located on the RPL root), does not require an 2305 IPv6-in-IPv6 header (in storing or non-storing mode), as the packet 2306 is originating at the root, and the root can insert the RPI and RH3 2307 headers directly into the packet, as it is formed. Such a packet is 2308 slightly smaller, but only can be sent to nodes (whether RPL aware or 2309 not), that will tolerate the RPL artifacts. 2311 An operator that finds itself with a high amount of traffic from the 2312 RPL root to RPL-not-aware-leaves, will have to do IPv6-in-IPv6 2313 encapsulation if the leaf is not tolerant of the RPL artifacts. Such 2314 an operator could otherwise omit this unnecessary header if it was 2315 certain of the properties of the leaf. 2317 As storing mode can not know the final path of the traffic, 2318 intolerant (that drop packets with RPL artifacts) leaf nodes can not 2319 be supported. 2321 10. Operational considerations of introducing 0x23 2323 This section describes the operational considerations of introducing 2324 the new RPI Option Type of 0x23. 2326 During bootstrapping the node gets the DIO with the information of 2327 RPI Option Type, indicating the new RPI in the DODAG Configuration 2328 option Flag. The DODAG root is in charge to configure the current 2329 network to the new value, through DIO messages and when all the nodes 2330 are set with the new value. The DODAG should change to a new DODAG 2331 version. In case of rebooting, the node does not remember the RPI 2332 Option Type. Thus, the DIO is sent with a flag indicating the new 2333 RPI Option Type. 2335 The DODAG Configuration option is contained in a RPL DIO message, 2336 which contains a unique DTSN counter. The leaf nodes respond to this 2337 message with DAO messages containing the same DTSN. This is a normal 2338 part of RPL routing; the RPL root therefore knows when the updated 2339 DODAG Configuration option has been seen by all nodes. 2341 Before the migration happens, all the RPL-aware nodes should support 2342 both values . The migration procedure is triggered when the DIO is 2343 sent with the flag indicating the new RPI Option Type. Namely, it 2344 remains at 0x63 until it is sure that the network is capable of 0x23, 2345 then it abruptly changes to 0x23. The 0x23 RPI Option allows to send 2346 packets to not-RPL nodes. The not-RPL nodes should ignore the option 2347 and continue processing the packets. 2349 As mentioned previously, indicating the new RPI in the DODAG 2350 Configuration option flag is a way to avoid the flag day (abrupt 2351 changeover) in a network using 0x63 as the RPI Option Type value. It 2352 is suggested that RPL implementations accept both 0x63 and 0x23 RPI 2353 Option type values when processing the header to enable 2354 interoperability. 2356 11. IANA Considerations 2358 11.1. Option Type in RPL Option 2360 This document updates the registration made in [RFC6553] Destination 2361 Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in 2362 Figure 38. 2364 +-------+-------------------+------------------------+---------- -+ 2365 | Hex | Binary Value | Description | Reference | 2366 + Value +-------------------+ + + 2367 | | act | chg | rest | | | 2368 +-------+-----+-----+-------+------------------------+------------+ 2369 | 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)| 2370 +-------+-----+-----+-------+------------------------+------------+ 2371 | 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] | 2372 | | | | | |[RFCXXXX](*)| 2373 +-------+-----+-----+-------+------------------------+------------+ 2375 Figure 38: Option Type in RPL Option.(*)represents this document 2377 DODAG Configuration option is updated as follows (Figure 39): 2379 +------------+-----------------+---------------+ 2380 | Bit number | Description | Reference | 2381 +------------+-----------------+---------------+ 2382 | 3 | RPI 0x23 enable | This document | 2383 +------------+-----------------+---------------+ 2385 Figure 39: DODAG Configuration option Flag to indicate the RPI-flag- 2386 day. 2388 11.2. Change to the DODAG Configuration Options Flags registry 2390 This document requests IANA to change the name of the "DODAG 2391 Configuration Option Flags" registry to "DODAG Configuration Option 2392 Flags for MOP 0..6". 2394 This document requests to be mentioned as a reference for this 2395 change. 2397 11.3. Change MOP value 7 to Reserved 2399 This document requests the changing the registration status of value 2400 7 in the Mode of Operation registry from Unassigned to Reserved. 2401 This change is in support of future work. 2403 This document requests to be mentioned as a reference for this entry 2404 in the registry. 2406 12. Security Considerations 2408 The security considerations covered in [RFC6553] and [RFC6554] apply 2409 when the packets are in the RPL Domain. 2411 The IPv6-in-IPv6 mechanism described in this document is much more 2412 limited than the general mechanism described in [RFC2473]. The 2413 willingness of each node in the LLN to decapsulate packets and 2414 forward them could be exploited by nodes to disguise the origin of an 2415 attack. 2417 While a typical LLN may be a very poor origin for attack traffic (as 2418 the networks tend to be very slow, and the nodes often have very low 2419 duty cycles), given enough nodes, LLNs could still have a significant 2420 impact, particularly if the attack is targeting another LLN. 2421 Additionally, some uses of RPL involve large backbone ISP scale 2422 equipment [I-D.ietf-anima-autonomic-control-plane], which may be 2423 equipped with multiple 100Gb/s interfaces. 2425 Blocking or careful filtering of IPv6-in-IPv6 traffic entering the 2426 LLN as described above will make sure that any attack that is mounted 2427 must originate from compromised nodes within the LLN. The use of 2428 BCP38 [BCP38] filtering at the RPL root on egress traffic will both 2429 alert the operator to the existence of the attack, as well as drop 2430 the attack traffic. As the RPL network is typically numbered from a 2431 single prefix, which is itself assigned by RPL, BCP38 filtering 2432 involves a single prefix comparison and should be trivial to 2433 automatically configure. 2435 There are some scenarios where IPv6-in-IPv6 traffic should be allowed 2436 to pass through the RPL root, such as the IPv6-in-IPv6 mediated 2437 communications between a new Pledge and the Join Registrar/ 2438 Coordinator (JRC) when using [I-D.ietf-anima-bootstrapping-keyinfra] 2439 and [I-D.ietf-6tisch-dtsecurity-zerotouch-join]. This is the case 2440 for the RPL root to do careful filtering: it occurs only when the 2441 Join Coordinator is not co-located inside the RPL root. 2443 With the above precautions, an attack using IPv6-in-IPv6 tunnels can 2444 only be by a node within the LLN on another node within the LLN. 2445 Such an attack could, of course, be done directly. An attack of this 2446 kind is meaningful only if the source addresses are either fake or if 2447 the point is to amplify return traffic. Such an attack, could also 2448 be done without the use of IPv6-in-IPv6 headers using forged source 2449 addresses. If the attack requires bi-directional communication, then 2450 IPv6-in-IPv6 provides no advantages. 2452 Whenever IPv6-in-IPv6 headers are being proposed, there is a concern 2453 about creating security issues. In the Security Considerations 2454 section of [RFC2473], it was suggested that tunnel entry and exit 2455 points can be secured by securing the IPv6 path between them. This 2456 recommendation is not practical for RPL networks. [RFC5406] goes 2457 into some detail on what additional details would be needed in order 2458 to "Use IPsec". Use of ESP would prevent [RFC8138] compression 2459 (compression must occur before encryption), and [RFC8138] compression 2460 is lossy in a way that prevents use of AH. These are minor issues. 2461 The major issue is how to establish trust enough such that IKEv2 2462 could be used. This would require a system of certificates to be 2463 present in every single node, including any Internet nodes that might 2464 need to communicate with the LLN. Thus, using IPsec requires a 2465 global PKI in the general case. 2467 More significantly, the use of IPsec tunnels to protect the IPv6-in- 2468 IPv6 headers would in the general case scale with the square of the 2469 number of nodes. This is a lot of resource for a constrained nodes 2470 on a constrained network. In the end, the IPsec tunnels would be 2471 providing only BCP38-like origin authentication! That is, IPsec 2472 provides a transitive guarantee to the tunnel exit point that the 2473 tunnel entry point did BCP38 on traffic going in. Just doing origin 2474 filtering per BCP 38 at the entry and exit of the LLN provides a 2475 similar level of security without all the scaling and trust problems 2476 related to IPv6 tunnels as discussed in RFC 2473. IPsec is not 2477 recommended. 2479 An LLN with hostile nodes within it would not be protected against 2480 impersonation with the LLN by entry/exit filtering. 2482 The RH3 header usage described here can be abused in equivalent ways 2483 (to disguise the origin of traffic and attack other nodes) with an 2484 IPv6-in-IPv6 header to add the needed RH3 header. As such, the 2485 attacker's RH3 header will not be seen by the network until it 2486 reaches the end host, which will decapsulate it. An end-host should 2487 be suspicious about an RH3 header which has additional hops which 2488 have not yet been processed, and SHOULD ignore such a second RH3 2489 header. 2491 In addition, the LLN will likely use [RFC8138] to compress the IPv6- 2492 in-IPv6 and RH3 headers. As such, the compressor at the RPL-root 2493 will see the second RH3 header and MAY choose to discard the packet 2494 if the RH3 header has not been completely consumed. A consumed 2495 (inert) RH3 header could be present in a packet that flows from one 2496 LLN, crosses the Internet, and enters another LLN. As per the 2497 discussion in this document, such headers do not need to be removed. 2498 However, there is no case described in this document where an RH3 is 2499 inserted in a non-storing network on traffic that is leaving the LLN, 2500 but this document should not preclude such a future innovation. It 2501 should just be noted that an incoming RH3 must be fully consumed, or 2502 very carefully inspected to match a policy that applies to this 2503 network and is correctly processed by the leaves. 2505 The RPI, if permitted to enter the LLN, could be used by an attacker 2506 to change the priority of a packet by selecting a different 2507 RPLInstanceID, perhaps one with a higher energy cost, for instance. 2508 It could also be that not all nodes are reachable in an LLN using the 2509 default RPLInstanceID, but a change of RPLInstanceID would permit an 2510 attacker to bypass such filtering. Like the RH3, an RPI is to be 2511 inserted by the RPL root on traffic entering the LLN by first 2512 inserting an IPv6-in-IPv6 header. The attacker's RPI therefore will 2513 not be seen by the network. Upon reaching the destination node the 2514 RPI has no further meaning and is just skipped; the presence of a 2515 second RPI will have no meaning to the end node as the packet has 2516 already been identified as being at it's final destination. 2518 For traffic leaving a RUL, if the RUL adds an opaque RPI then the 6LR 2519 as a RPL border router SHOULD rewrite the RPI to indicate the 2520 selected Instance and set the flags. This is done in order to avoid: 2521 1) The leaf is an external router that passes a packet that it did 2522 not generate and that carries an unrelated RPI and 2) The leaf is an 2523 attacker or presents misconfiguration and tries to inject traffic in 2524 a protected instance. Also, this applies in the case where the leaf 2525 is aware of the RPL instance and passes a correct RPI; the 6LR needs 2526 a configuration that allows that leaf to inject in that instance. 2528 The RH3 and RPIs could be abused by an attacker inside of the network 2529 to route packets on non-obvious ways, perhaps eluding observation. 2530 This usage appears consistent with a normal operation of [RFC6997] 2531 and can not be restricted at all. This is a feature, not a bug. 2533 [RFC7416] deals with many other threats to LLNs not directly related 2534 to the use of IPv6-in-IPv6 headers, and this document does not change 2535 that analysis. 2537 Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an 2538 attack on another part of the LLN, while disguising the origin of the 2539 attack. The mechanism can even be abused to make it appear that the 2540 attack is coming from outside the LLN, and unless countered, this 2541 could be used to mount a Distributed Denial Of Service attack upon 2542 nodes elsewhere in the Internet. See [DDOS-KREBS] for an example of 2543 such attacks already seen in the real world. 2545 If an attack comes from inside of LLN, it can be alleviated with SAVI 2546 (Source Address Validation Improvement) using [RFC8505] with 2547 [I-D.ietf-6lo-ap-nd]. The attacker will not be able to source 2548 traffic with an address that is not registered, and the registration 2549 process checks for topological correctness. Notice that there is an 2550 L2 authentication in most of the cases. If an attack comes from 2551 outside LLN IPv6-in- IPv6 can be used to hide inner routing headers, 2552 but by construction, the RH3 can typically only address nodes within 2553 the LLN. That is, an RH3 with a CmprI less than 8 , should be 2554 considered an attack (see RFC6554, section 3). 2556 Nodes outside of the LLN will need to pass IPv6-in-IPv6 traffic 2557 through the RPL root to perform this attack. To counter, the RPL 2558 root SHOULD either restrict ingress of IPv6-in-IPv6 packets (the 2559 simpler solution), or it SHOULD walk the IP header extension chain 2560 until it can inspect the upper-layer-payload as described in 2561 [RFC7045]. In particular, the RPL root SHOULD do [BCP38] processing 2562 on the source addresses of all IP headers that it examines in both 2563 directions. 2565 Note: there are some situations where a prefix will spread across 2566 multiple LLNs via mechanisms such as the one described in 2567 [I-D.ietf-6lo-backbone-router]. In this case the BCP38 filtering 2568 needs to take this into account, either by exchanging detailed 2569 routing information on each LLN, or by moving the BCP38 filtering 2570 further towards the Internet, so that the details of the multiple 2571 LLNs do not matter. 2573 13. Acknowledgments 2575 This work is done thanks to the grant given by the StandICT.eu 2576 project. 2578 A special BIG thanks to C. M. Heard for the help with the 2579 Section 4. Much of the redaction in that section is based on his 2580 comments. 2582 Additionally, the authors would like to acknowledge the review, 2583 feedback, and comments of (alphabetical order): Dominique Barthel, 2584 Robert Cragie, Simon Duquennoy, Ralph Droms, Cenk Guendogan, Rahul 2585 Jadhav, Benjamin Kaduk, Matthias Kovatsch, Gustavo Mercado, 2586 Subramanian Moonesamy, Marcela Orbiscay, Charlie Perkins, Cristian 2587 Perez, Alvaro Retana, Peter van der Stok, Xavier Vilajosana, Eric 2588 Vyncke and Thomas Watteyne. 2590 14. References 2592 14.1. Normative References 2594 [BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering: 2595 Defeating Denial of Service Attacks which employ IP Source 2596 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 2597 May 2000, . 2599 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2600 Requirement Levels", BCP 14, RFC 2119, 2601 DOI 10.17487/RFC2119, March 1997, 2602 . 2604 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 2605 Notification", RFC 6040, DOI 10.17487/RFC6040, November 2606 2010, . 2608 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 2609 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 2610 DOI 10.17487/RFC6282, September 2011, 2611 . 2613 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 2614 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 2615 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 2616 Low-Power and Lossy Networks", RFC 6550, 2617 DOI 10.17487/RFC6550, March 2012, 2618 . 2620 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 2621 Power and Lossy Networks (RPL) Option for Carrying RPL 2622 Information in Data-Plane Datagrams", RFC 6553, 2623 DOI 10.17487/RFC6553, March 2012, 2624 . 2626 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 2627 Routing Header for Source Routes with the Routing Protocol 2628 for Low-Power and Lossy Networks (RPL)", RFC 6554, 2629 DOI 10.17487/RFC6554, March 2012, 2630 . 2632 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 2633 of IPv6 Extension Headers", RFC 7045, 2634 DOI 10.17487/RFC7045, December 2013, 2635 . 2637 [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power 2638 Wireless Personal Area Network (6LoWPAN) Paging Dispatch", 2639 RFC 8025, DOI 10.17487/RFC8025, November 2016, 2640 . 2642 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 2643 "IPv6 over Low-Power Wireless Personal Area Network 2644 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 2645 April 2017, . 2647 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2648 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2649 May 2017, . 2651 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2652 (IPv6) Specification", STD 86, RFC 8200, 2653 DOI 10.17487/RFC8200, July 2017, 2654 . 2656 14.2. Informative References 2658 [DDOS-KREBS] 2659 Goodin, D., "Record-breaking DDoS reportedly delivered by 2660 >145k hacked cameras", September 2016, 2661 . 2664 [I-D.ietf-6lo-ap-nd] 2665 Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, 2666 "Address Protected Neighbor Discovery for Low-power and 2667 Lossy Networks", draft-ietf-6lo-ap-nd-23 (work in 2668 progress), April 2020. 2670 [I-D.ietf-6lo-backbone-router] 2671 Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 2672 Backbone Router", draft-ietf-6lo-backbone-router-20 (work 2673 in progress), March 2020. 2675 [I-D.ietf-6tisch-dtsecurity-zerotouch-join] 2676 Richardson, M., "6tisch Zero-Touch Secure Join protocol", 2677 draft-ietf-6tisch-dtsecurity-zerotouch-join-04 (work in 2678 progress), July 2019. 2680 [I-D.ietf-anima-autonomic-control-plane] 2681 Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic 2682 Control Plane (ACP)", draft-ietf-anima-autonomic-control- 2683 plane-30 (work in progress), October 2020. 2685 [I-D.ietf-anima-bootstrapping-keyinfra] 2686 Pritikin, M., Richardson, M., Eckert, T., Behringer, M., 2687 and K. Watsen, "Bootstrapping Remote Secure Key 2688 Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- 2689 keyinfra-45 (work in progress), November 2020. 2691 [I-D.ietf-intarea-tunnels] 2692 Touch, J. and M. Townsley, "IP Tunnels in the Internet 2693 Architecture", draft-ietf-intarea-tunnels-10 (work in 2694 progress), September 2019. 2696 [I-D.ietf-roll-unaware-leaves] 2697 Thubert, P. and M. Richardson, "Routing for RPL Leaves", 2698 draft-ietf-roll-unaware-leaves-28 (work in progress), 2699 December 2020. 2701 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2702 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 2703 December 1998, . 2705 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 2706 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 2707 December 1998, . 2709 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 2710 Control Message Protocol (ICMPv6) for the Internet 2711 Protocol Version 6 (IPv6) Specification", STD 89, 2712 RFC 4443, DOI 10.17487/RFC4443, March 2006, 2713 . 2715 [RFC5406] Bellovin, S., "Guidelines for Specifying the Use of IPsec 2716 Version 2", BCP 146, RFC 5406, DOI 10.17487/RFC5406, 2717 February 2009, . 2719 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 2720 "IPv6 Flow Label Specification", RFC 6437, 2721 DOI 10.17487/RFC6437, November 2011, 2722 . 2724 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 2725 Bormann, "Neighbor Discovery Optimization for IPv6 over 2726 Low-Power Wireless Personal Area Networks (6LoWPANs)", 2727 RFC 6775, DOI 10.17487/RFC6775, November 2012, 2728 . 2730 [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and 2731 J. Martocci, "Reactive Discovery of Point-to-Point Routes 2732 in Low-Power and Lossy Networks", RFC 6997, 2733 DOI 10.17487/RFC6997, August 2013, 2734 . 2736 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 2737 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 2738 2014, . 2740 [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., 2741 and M. Richardson, Ed., "A Security Threat Analysis for 2742 the Routing Protocol for Low-Power and Lossy Networks 2743 (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, 2744 . 2746 [RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal 2747 IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH) 2748 Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180, 2749 May 2017, . 2751 [RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node 2752 Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504, 2753 January 2019, . 2755 [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. 2756 Perkins, "Registration Extensions for IPv6 over Low-Power 2757 Wireless Personal Area Network (6LoWPAN) Neighbor 2758 Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, 2759 . 2761 Authors' Addresses 2763 Maria Ines Robles 2764 Universidad Tecno. Nac.(UTN)-FRM, Argentina/ Aalto University Finland 2766 Email: mariainesrobles@gmail.com 2768 Michael C. Richardson 2769 Sandelman Software Works 2770 470 Dawson Avenue 2771 Ottawa, ON K1Z 5V7 2772 CA 2774 Email: mcr+ietf@sandelman.ca 2775 URI: http://www.sandelman.ca/mcr/ 2777 Pascal Thubert 2778 Cisco Systems, Inc 2779 Building D 2780 45 Allee des Ormes - BP1200 2781 MOUGINS - Sophia Antipolis 06254 2782 FRANCE 2784 Phone: +33 497 23 26 34 2785 Email: pthubert@cisco.com