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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: September 24, 2020 P. Thubert 7 Cisco 8 March 23, 2020 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-38 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 September 24, 2020. 45 Copyright Notice 47 Copyright (c) 2020 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 RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 7 67 4.1. Updates to RFC6550: Advertising External Routes with Non- 68 Storing Mode Signaling. . . . . . . . . . . . . . . . . . 7 69 4.2. Updates to RFC6553: Indicating the new RPI Option Type. . 8 70 4.3. Updates to RFC6550: Indicating the new RPI in the 71 DODAG Configuration option Flag. . . . . . . . . . . . . 11 72 4.4. Updates to RFC8138: Indicating the way to decompress with 73 the new RPI Option Type. . . . . . . . . . . . . . . . . 12 74 5. Sample/reference topology . . . . . . . . . . . . . . . . . . 14 75 6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 16 76 7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 19 77 7.1. Storing Mode: Interaction between Leaf and Root . . . . . 20 78 7.1.1. SM: Example of Flow from RAL to Root . . . . . . . . 21 79 7.1.2. SM: Example of Flow from Root to RAL . . . . . . . . 22 80 7.1.3. SM: Example of Flow from Root to RUL . . . . . . . . 22 81 7.1.4. SM: Example of Flow from RUL to Root . . . . . . . . 24 82 7.2. SM: Interaction between Leaf and Internet. . . . . . . . 25 83 7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 25 84 7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 27 85 7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 28 86 7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 29 87 7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 30 88 7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 30 89 7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 31 90 7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 33 91 7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 34 92 8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 35 93 8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 37 94 8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 38 95 8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 39 96 8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 39 97 8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 40 98 8.2. Non-Storing Mode: Interaction between Leaf and Internet . 41 99 8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 42 100 8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 43 101 8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 44 102 8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 45 103 8.3. Non-SM: Interaction between leaves . . . . . . . . . . . 46 104 8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 46 105 8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 49 106 8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 51 107 8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 52 108 9. Operational Considerations of supporting 109 RUL-leaves . . . . . . . . . . . . . . . . . . . . . . . . . 53 110 10. Operational considerations of introducing 0x23 . . . . . . . 54 111 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 54 112 12. Security Considerations . . . . . . . . . . . . . . . . . . . 55 113 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 58 114 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 59 115 14.1. Normative References . . . . . . . . . . . . . . . . . . 59 116 14.2. Informative References . . . . . . . . . . . . . . . . . 60 117 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 62 119 1. Introduction 121 RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) 122 [RFC6550] is a routing protocol for constrained networks. [RFC6553] 123 defines the RPL Option carried within the IPv6 Hop-by-Hop Header to 124 carry the RPLInstanceID and quickly identify inconsistencies (loops) 125 in the routing topology. The RPL Option is commonly referred to as 126 the RPL Packet Information (RPI) though the RPI is really the 127 abstract information that is defined in [RFC6550] and transported in 128 the RPL Option. RFC6554 [RFC6554] defines the "RPL Source Route 129 Header" (RH3), an IPv6 Extension Header to deliver datagrams within a 130 RPL routing domain, particularly in non-storing mode. 132 These various items are referred to as RPL artifacts, and they are 133 seen on all of the data-plane traffic that occurs in RPL routed 134 networks; they do not in general appear on the RPL control plane 135 traffic at all which is mostly Hop-by-Hop traffic (one exception 136 being DAO messages in non-storing mode). 138 It has become clear from attempts to do multi-vendor 139 interoperability, and from a desire to compress as many of the above 140 artifacts as possible that not all implementers agree when artifacts 141 are necessary, or when they can be safely omitted, or removed. 143 The ROLL WG analysized how [RFC2460] rules apply to storing and non- 144 storing use of RPL. The result was 24 data plane use cases. They 145 are exhaustively outlined here in order to be completely unambiguous. 146 During the processing of this document, new rules were published as 147 [RFC8200], and this document was updated to reflect the normative 148 changes in that document. 150 This document updates [RFC6553], changing the value of the Option 151 Type of the RPL Option to make [RFC8200] routers ignore this option 152 when not recognized. 154 A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a 155 mechanism for compressing RPL Option information and Routing Header 156 type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6 157 technique. 159 Since some of the uses cases here described, use IPv6-in-IPv6 160 encapsulation. It MUST take in consideration, when encapsulation is 161 applied, the RFC6040 [RFC6040], which defines how the explicit 162 congestion notification (ECN) field of the IP header should be 163 constructed on entry to and exit from any IPV6-in-IPV6 tunnel. 164 Additionally, it is recommended the reading of 165 [I-D.ietf-intarea-tunnels] that explains the relationship of IP 166 tunnels to existing protocol layers and the challenges in supporting 167 IP tunneling. 169 Non-constrained uses of RPL are not in scope of this document, and 170 applicability statements for those uses may provide different advice, 171 E.g. [I-D.ietf-anima-autonomic-control-plane]. 173 1.1. Overview 175 The rest of the document is organized as follows: Section 2 describes 176 the used terminology. Section 3 provides a RPL Overview. Section 4 177 describes the updates to RFC6553, RFC6550 and RFC 8138. Section 5 178 provides the reference topology used for the uses cases. Section 6 179 describes the uses cases included. Section 7 describes the storing 180 mode cases and section 8 the non-storing mode cases. Section 9 181 describes the operational considerations of supporting RPL-unaware- 182 leaves. Section 10 depicts operational considerations for the 183 proposed change on RPI Option Type, section 11 the IANA 184 considerations and then section 12 describes the security aspects. 186 2. Terminology and Requirements Language 188 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 189 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 190 "OPTIONAL" in this document are to be interpreted as described in BCP 191 14 [RFC2119] [RFC8174] when, and only when, they appear in all 192 capitals, as shown here. 194 Terminology defined in [RFC7102] applies to this document: LLN, RPL, 195 RPL domain and ROLL. 197 RPL Leaf: An IPv6 host that is attached to a RPL router and obtains 198 connectivity through a RPL Destination Oriented Directed Acyclic 199 Graph (DODAG). As an IPv6 node, a RPL Leaf is expected to ignore a 200 consumed Routing Header and as an IPv6 host, it is expected to ignore 201 a Hop-by-Hop header. It results that a RPL Leaf can correctly 202 receive a packet with RPL artifacts. On the other hand, a RPL Leaf 203 is not expected to generate RPL artifacts or to support IP-in-IP 204 encapsulation. For simplification, this document uses the standalone 205 term leaf to mean a RPL leaf. 207 RPL Packet Information (RPI): The abstract information that [RFC6550] 208 places in IP packets. The term is commonly used, including in this 209 document, to refer to the RPL Option [RFC6553] that transports that 210 abstract information in an IPv6 Hob-by-Hop Header. 212 RPL-aware-node (RAN): A device which implements RPL. Please note 213 that the device can be found inside the LLN or outside LLN. 215 RPL-Aware-Leaf(RAL): A RPL-aware-node that is also a RPL Leaf. 217 RPL-unaware-node: A device which does not implement RPL, thus the 218 device is not-RPL-aware. Please note that the device can be found 219 inside the LLN. 221 RPL-Unaware-Leaf(RUL): A RPL-unaware-node that is also a RPL Leaf. 223 6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any 224 host or router participating in a LoWPAN. This term is used when 225 referring to situations in which either a host or router can play the 226 role described.". In this document, a 6LN acts as a leaf. 228 6LoWPAN Router (6LR): [RFC6775] defines it as:" An intermediate 229 router in the LoWPAN that is able to send and receive Router 230 Advertisements (RAs) and Router Solicitations (RSs) as well as 231 forward and route IPv6 packets. 6LoWPAN routers are present only in 232 route-over topologies." 233 6LoWPAN Border Router (6LBR): [RFC6775] defines it as:"A border 234 router located at the junction of separate 6LoWPAN networks or 235 between a 6LoWPAN network and another IP network. There may be one 236 or more 6LBRs at the 6LoWPAN network boundary. A 6LBR is the 237 responsible authority for IPv6 prefix propagation for the 6LoWPAN 238 network it is serving. An isolated LoWPAN also contains a 6LBR in 239 the network, which provides the prefix(es) for the isolated network." 241 Flag Day: A transition that involves having a network with different 242 values of RPI Option Type. Thus the network does not work correctly 243 (Lack of interoperation). 245 Non-Storing Mode (Non-SM): RPL mode of operation in which the RPL- 246 aware-nodes send information to the root about their parents. Thus, 247 the root knows the topology. Because the root knows the topology, 248 the intermediate 6LRs do not maintain routing state and source 249 routing is needed. 251 Storing Mode (SM): RPL mode of operation in which RPL-aware-nodes 252 (6LRs) maintain routing state (of the children) so that source 253 routing is not needed. 255 Note: Due to lack of space in some figures (tables) we refer to IPv6- 256 in-IPv6 as IP6-IP6. 258 3. RPL Overview 260 RPL defines the RPL Control messages (control plane), a new ICMPv6 261 [RFC4443] message with Type 155. DIS (DODAG Information 262 Solicitation), DIO (DODAG Information Object) and DAO (Destination 263 Advertisement Object) messages are all RPL Control messages but with 264 different Code values. A RPL Stack is shown in Figure 1. 266 +--------------+ 267 | Upper Layers | 268 | | 269 +--------------+ 270 | RPL | 271 | | 272 +--------------+ 273 | ICMPv6 | 274 | | 275 +--------------+ 276 | IPv6 | 277 | | 278 +--------------+ 279 | 6LoWPAN | 280 | | 281 +--------------+ 282 | PHY-MAC | 283 | | 284 +--------------+ 286 Figure 1: RPL Stack. 288 RPL supports two modes of Downward traffic: in storing mode (SM), it 289 is fully stateful; in non-storing mode (Non-SM), it is fully source 290 routed. A RPL Instance is either fully storing or fully non-storing, 291 i.e. a RPL Instance with a combination of storing and non-storing 292 nodes is not supported with the current specifications at the time of 293 writing this document. 295 4. Updates to RFC6553, RFC6550 and RFC8138 297 4.1. Updates to RFC6550: Advertising External Routes with Non-Storing 298 Mode Signaling. 300 Section 6.7.8. of [RFC6550] introduces the 'E' flag that is set to 301 indicate that the 6LR that generates the DAO redistributes external 302 targets into the RPL network. An external Target is a Target that 303 has been learned through an alternate protocol, for instance a route 304 to a prefix that is outside the RPL domain but reachable via a 6LR. 305 Being outside of the RPL domain, a node that is reached via an 306 external target cannot be guaranteed to ignore the RPL artifacts and 307 cannot be expected to process the [RFC8138] compression correctly. 308 This means that the RPL artifacts should be contained in an IP-in-IP 309 encapsulation that is removed by the 6LR, and that any remaining 310 compression should be expanded by the 6LR before it forwards a packet 311 outside the RPL domain. 313 This specification updates [RFC6550] to RECOMMEND that external 314 targets are advertised using Non-Storing Mode DAO messaging even in a 315 Storing-Mode network. This way, external routes are not advertised 316 within the DODAG and all packets to an external target reach the Root 317 like normal Non-Storing Mode traffic. The Non-Storing Mode DAO 318 informs the Root of the address of the 6LR that injects the external 319 route, and the root uses IP-in-IP encapsulation to that 6LR, which 320 terminates the IP-in-IP tunnel and forwards the original packet 321 outside the RPL domain free of RPL artifacts. In the other 322 direction, for traffic coming from an external target into the LLN, 323 the parent (6LR) that injects the traffic always encapsulates to the 324 root. This whole operation is transparent to intermediate routers 325 that only see traffic between the 6LR and the Root, and only the Root 326 and the 6LRs that inject external routes in the network need to be 327 upgraded to add this function to the network. 329 A RUL is a special case of external target when the target is 330 actually a host and it is known to support a consumed Routing Header 331 and to ignore a HbH header as prescribed by [RFC8200]. The target 332 may have been learned through as a host route or may have been 333 registered to the 6LR using [RFC8505]. 335 In order to enable IP-in-IP all the way to a 6LN, it is beneficial 336 that the 6LN supports decapsulating IP-in-IP, but that is not assumed 337 by [RFC8504]. If the 6LN is a RUL, the Root that encapsulates a 338 packet SHOULD terminate the tunnel at a parent 6LR unless it is aware 339 that the RUL supports IP-in-IP decapsulation. 341 A node that is reachable over an external route is not expected to 342 support [RFC8138]. Whether a decapsulation took place or not and 343 even when the 6LR is delivering the packet to a RUL, the 6LR that 344 injected an external route MUST uncompress the packet before 345 forwarding over that external route. 347 4.2. Updates to RFC6553: Indicating the new RPI Option Type. 349 This modification is required in order to be able to send, for 350 example, IPv6 packets from a RPL-Aware-Leaf to a RPL-unaware node 351 through Internet (see Section 7.2.1), without requiring IPv6-in-IPv6 352 encapsulation. 354 [RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in 355 the Option Type field of the RPL Option, the two high order bits must 356 be set to '01' and the third bit is equal to '1'. The first two bits 357 indicate that the IPv6 node must discard the packet if it doesn't 358 recognize the Option Type, and the third bit indicates that the 359 Option Data may change in route. The remaining bits serve as the 360 Option Type. 362 +-------+-------------------+----------------+-----------+ 363 | Hex | Binary Value | Description | Reference | 364 + Value +-------------------+ + + 365 | | act | chg | rest | | | 366 +-------+-----+-----+-------+----------------+-----------+ 367 | 0x63 | 01 | 1 | 00011 | RPL Option | [RFC6553] | 368 +-------+-----+-----+-------+----------------+-----------+ 370 Figure 2: Option Type in RPL Option. 372 This document illustrates that it is not always possible to know for 373 sure at the source that a packet will only travel within the RPL 374 domain or may leave it. 376 At the time [RFC6553] was published, leaking a Hop-by-Hop header in 377 the outer IPv6 header chain could potentially impact core routers in 378 the internet. So at that time, it was decided to encapsulate any 379 packet with a RPL Option using IPv6-in-IPv6 in all cases where it was 380 unclear whether the packet would remain within the RPL domain. In 381 the exception case where a packet would still leak, the Option Type 382 would ensure that the first router in the Internet that does not 383 recognize the option would drop the packet and protect the rest of 384 the network. 386 Even with [RFC8138], where the IPv6-in-IPv6 header is compressed, 387 this approach yields extra bytes in a packet; this means consuming 388 more energy, more bandwidth, incurring higher chances of loss and 389 possibly causing a fragmentation at the 6LoWPAN level. This impacts 390 the daily operation of constrained devices for a case that generally 391 does not happen and would not heavily impact the core anyway. 393 While intention was and remains that the Hop-by-Hop header with a RPL 394 Option should be confined within the RPL domain, this specification 395 modifies this behavior in order to reduce the dependency on IPv6-in- 396 IPv6 and protect the constrained devices. Section 4 of [RFC8200] 397 clarifies the behaviour of routers in the Internet as follows: "it is 398 now expected that nodes along a packet's delivery path only examine 399 and process the Hop-by-Hop Options header if explicitly configured to 400 do so". 402 When unclear about the travel of a packet, it becomes preferable for 403 a source not to encapsulate, accepting the fact that the packet may 404 leave the RPL domain on its way to its destination. In that event, 405 the packet should reach its destination and should not be discarded 406 by the first node that does not recognize the RPL Option. But with 407 the current value of the Option Type, if a node in the Internet is 408 configured to process the Hop-by-Hop header, and if such node 409 encounters an option with the first two bits set to 01 and conforms 410 to [RFC8200], it will drop the packet. Host systems should do the 411 same, irrespective of the configuration. 413 Thus, this document updates the Option Type of the RPL Option 414 [RFC6553], abusively naming it RPI Option Type for simplicity, to 415 (Figure 3): the two high order bits MUST be set to '00' and the third 416 bit is equal to '1'. The first two bits indicate that the IPv6 node 417 MUST skip over this option and continue processing the header 418 ([RFC8200] Section 4.2) if it doesn't recognize the Option Type, and 419 the third bit continues to be set to indicate that the Option Data 420 may change en route. The rightmost five bits remain at 0x3(00011). 421 This ensures that a packet that leaves the RPL domain of an LLN (or 422 that leaves the LLN entirely) will not be discarded when it contains 423 the RPL Option. 425 With the new Option Type, if an IPv6 (intermediate) node (RPL-not- 426 capable) receives a packet with an RPL Option, it should ignore the 427 Hop-by-Hop RPL Option (skip over this option and continue processing 428 the header). This is relevant, as it was mentioned previously, in 429 the case that there is a flow from RAL to Internet (see 430 Section 7.2.1). 432 This is a significant update to [RFC6553]. 434 +-------+-------------------+-------------+------------+ 435 | Hex | Binary Value | Description | Reference | 436 + Value +-------------------+ + + 437 | | act | chg | rest | | | 438 +-------+-----+-----+-------+-------------+------------+ 439 | 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)| 440 +-------+-----+-----+-------+-------------+------------+ 442 Figure 3: Revised Option Type in RPL Option. (*)represents this 443 document 445 Without the signaling described below, this change would otherwise 446 create a lack of interoperation (flag day) for existing networks 447 which are currently using 0x63 as the RPI Option Type value. A move 448 to 0x23 will not be understood by those networks. It is suggested 449 that RPL implementations accept both 0x63 and 0x23 when processing 450 the header. 452 When forwarding packets, implementations SHOULD use the same value of 453 RPI Type as was received. This is required because the RPI Option 454 Type does not change en route ([RFC8200] - Section 4.2). It allows 455 the network to be incrementally upgraded and allows the DODAG root to 456 know which parts of the network have been upgraded. 458 When originating new packets, implementations SHOULD have an option 459 to determine which value to originate with, this option is controlled 460 by the DIO option described below. 462 The change of RPI Option Type from 0x63 to 0x23, makes all [RFC8200] 463 Section 4.2 compliant nodes tolerant of the RPL artifacts. There is 464 therefore no longer a necessity to remove the artifacts when sending 465 traffic to the Internet. This change clarifies when to use IPv6-in- 466 IPv6 headers, and how to address them: The Hop-by-Hop Options header 467 containing the RPI MUST always be added when 6LRs originate packets 468 (without IPv6-in-IPv6 headers), and IPv6-in-IPv6 headers MUST always 469 be added when a 6LR finds that it needs to insert a Hop-by-Hop 470 Options header containing the RPL Option. The IPv6-in-IPv6 header is 471 to be addressed to the RPL root when on the way up, and to the end- 472 host when on the way down. 474 In the non-storing case, dealing with not-RPL aware leaf nodes is 475 much easier as the 6LBR (DODAG root) has complete knowledge about the 476 connectivity of all DODAG nodes, and all traffic flows through the 477 root node. 479 The 6LBR can recognize not-RPL aware leaf nodes because it will 480 receive a DAO about that node from the 6LR immediately above that 481 not-RPL aware node. 483 The non-storing mode case does not require the type change from 0x63 484 to 0x23, as the root can always create the right packet. The type 485 change does not adversely affect the non-storing case. 487 4.3. Updates to RFC6550: Indicating the new RPI in the DODAG 488 Configuration option Flag. 490 In order to avoid a Flag Day caused by lack of interoperation between 491 new RPI Option Type (0x23) and old RPI Option Type (0x63) nodes, this 492 section defines a flag in the DIO Configuration option, to indicate 493 when the new RPI Option Type can be safely used. This means, the 494 flag is going to indicate the value of Option Type that the network 495 will be using for the RPL Option. Thus, when a node joins to a 496 network will know which value to use. With this, RPL-capable nodes 497 know if it is safe to use 0x23 when creating a new RPL Option. A 498 node that forwards a packet with an RPI MUST NOT modify the Option 499 Type of the RPL Option. 501 This is done using a DODAG Configuration option flag which will 502 signal "RPI 0x23 enable" and propagate through the network. 503 Section 6.3.1. of [RFC6550] defines a 3-bit Mode of Operation (MOP) 504 in the DIO Base Object. The flag is defined only for MOP value 505 between 0 to 6. For a MOP value of 7 or above, the flag MAY indicate 506 something different and MUST NOT be interpreted as "RPI 0x23 enable" 507 unless the specification of the MOP indicates to do so. 509 As stated in [RFC6550] the DODAG Configuration option is present in 510 DIO messages. The DODAG Configuration option distributes 511 configuration information. It is generally static, and does not 512 change within the DODAG. This information is configured at the DODAG 513 root and distributed throughout the DODAG with the DODAG 514 Configuration option. Nodes other than the DODAG root do not modify 515 this information when propagating the DODAG Configuration option. 517 Currently, the DODAG Configuration option in [RFC6550] states: "the 518 unused bits MUST be initialize to zero by the sender and MUST be 519 ignored by the receiver". If the flag is received with a value zero 520 (which is the default), then new nodes will remain in RFC6553 521 Compatible Mode; originating traffic with the old-RPI Option Type 522 (0x63) value. If the flag is received with a value of 1, then the 523 value for the RPL Option MUST be set to 0x23. 525 Bit number three of the flag field in the DODAG Configuration option 526 is to be used as shown in Figure 4 (which is the same as Figure 39 in 527 Section 11 and is shown here for convenience): 529 +------------+-----------------+---------------+ 530 | Bit number | Description | Reference | 531 +------------+-----------------+---------------+ 532 | 3 | RPI 0x23 enable | This document | 533 +------------+-----------------+---------------+ 535 Figure 4: DODAG Configuration option Flag to indicate the RPI-flag- 536 day. 538 In the case of reboot, the node (6LN or 6LR) does not remember the 539 RPI Option Type (i.e., whether or not the flag is set), so the node 540 will not trigger DIO messages until a DIO message is received 541 indicating the RPI value to be used. The node will use the value 542 0x23 if the network supports this feature 544 4.4. Updates to RFC8138: Indicating the way to decompress with the new 545 RPI Option Type. 547 This modification is required in order to be able to decompress the 548 RPL Option with the new Option Type of 0x23. 550 RPI-6LoRH header provides a compressed form for the RPL RPI; see 551 [RFC8138], Section 6. A node that is decompressing this header MUST 552 decompress using the RPI Option Type that is currently active: that 553 is, a choice between 0x23 (new) and 0x63 (old). The node will know 554 which to use based upon the presence of the flag in the DODAG 555 Configuration option defined in Section 4.3. E.g. If the network is 556 in 0x23 mode (by DIO option), then it should be decompressed to 0x23. 558 [RFC8138] section 7 documents how to compress the IPv6-in-IPv6 559 header. 561 There are potential significant advantages to having a single code 562 path that always processes IPv6-in-IPv6 headers with no conditional 563 branches. 565 In Storing Mode, the scenarios where the flow goes from RAL to RUL 566 and RUL to RUL include compression of the IPv6-in-IPv6 and RPI 567 headers. The use of the IPv6-in-IPv6 header is MANDATORY in this 568 case, and it SHOULD be compressed with [RFC8138] section 7. Figure 5 569 illustrates the case in Storing mode where the packet is received 570 from the Internet, then the root encapsulates the packet to insert 571 the RPI. In that example, the leaf is not known to support RFC 8138, 572 and the packet is encapsulated to the 6LR that is the parent and last 573 hop to the final destination. 575 +-+ ... -+-+ ... +-+- ... -+-+- +-+-+-+ ... +-+-+ ... -+++ ... +-... 576 |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP 577 |Page 1 |Type1 S=0| 6LoRH |6LoRH |LOWPAN_IPHC| UDP | hdr |Payld 578 +-+ ... -+-+ ... +-+- ... -+-+-.+-+-+-+-+ ... +-+-+ ... -+ ... +-... 579 <-4bytes-> <- RFC 6282 -> 580 No RPL artifact 582 Figure 5: RPI Inserted by the Root in Storing Mode 584 In Figure 5, the source of the IPv6-in-IPv6 encapsulation is the 585 Root, so it is elided in the IP-in-IP 6LoRH. The destination is the 586 parent 6LR of the destination of the inner packet so it cannot be 587 elided. It is placed as the single entry in an SRH-6LoRH as the 588 first 6LoRH. There is a single entry so the SRH-6LoRH Size is 0. In 589 that example, the type is 1 so the 6LR address is compressed to 2 590 bytes. It results that the total length of the SRH-6LoRH is 4 bytes. 591 Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP 592 6LoRH is removed, all the router headers that precede it are also 593 removed. The Paging Dispatch [RFC8025] may also be removed if there 594 was no previous Page change to a Page other than 0 or 1, since the 595 LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and 596 in Page 1. The resulting packet to the destination is the inner 597 packet compressed with [RFC6282]. 599 5. Sample/reference topology 601 A RPL network in general is composed of a 6LBR, a Backbone Router 602 (6BBR), a 6LR and a 6LN as a leaf logically organized in a DODAG 603 structure. 605 Figure 6 shows the reference RPL Topology for this document. The 606 letters above the nodes are there so that they may be referenced in 607 subsequent sections. In the figure, 6LR represents a full router 608 node. The 6LN is a RPL aware router, or host (as a leaf). 609 Additionally, for simplification purposes, it is supposed that the 610 6LBR has direct access to Internet and is the root of the DODAG, thus 611 the 6BBR is not present in the figure. 613 The 6LN leaves (RAL) marked as (F, H and I) are RPL nodes with no 614 children hosts. 616 The leaves marked as RUL (G and J) are devices which do not speak RPL 617 at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/ 618 DAC and efficient-ND only to participate in the network [RFC6775]. 619 In the document these leaves (G and J) are also referred to as an 620 IPv6 node. 622 The 6LBR ("A") in the figure is the root of the Global DODAG. 624 +------------+ 625 | INTERNET ----------+ 626 | | | 627 +------------+ | 628 | 629 | 630 | 631 A | 632 +-------+ 633 |6LBR | 634 +-----------|(root) |-------+ 635 | +-------+ | 636 | | 637 | | 638 | | 639 | | 640 | B |C 641 +---|---+ +---|---+ 642 | 6LR | | 6LR | 643 +---------| |--+ +--- ---+ 644 | +-------+ | | +-------+ | 645 | | | | 646 | | | | 647 | | | | 648 | | | | 649 | D | E | | 650 +-|-----+ +---|---+ | | 651 | 6LR | | 6LR | | | 652 | | +------ | | | 653 +---|---+ | +---|---+ | | 654 | | | | | 655 | | +--+ | | 656 | | | | | 657 | | | | | 658 | | | I | J | 659 F | | G | H | | 660 +-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+ 661 | RAL | | RUL | | RAL | | RAL | | RUL | 662 | 6LN | | 6LN | | 6LN | | 6LN | | 6LN | 663 +-------+ +-------+ +------+ +-------+ +-------+ 665 Figure 6: A reference RPL Topology. 667 6. Use cases 669 In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6 670 encapsulation are going to be analyzed for a number of representative 671 traffic flows. 673 This document assumes that the LLN is using the no-drop RPI Option 674 Type of 0x23. 676 The use cases describe the communication in the following cases: - 677 Between RPL-aware-nodes with the root (6LBR) - Between RPL-aware- 678 nodes with the Internet - Between RUL nodes within the LLN (e.g. see 679 Section 7.1.4) - Inside of the LLN when the final destination address 680 resides outside of the LLN (e.g. see Section 7.2.3). 682 The uses cases are as follows: 684 Interaction between Leaf and Root: 686 RAL to root 688 root to RAL 690 RUL to root 692 root to RUL 694 Interaction between Leaf and Internet: 696 RAL to Internet 698 Internet to RAL 700 RUL to Internet 702 Internet to RUL 704 Interaction between leaves: 706 RAL to RAL 708 RAL to RUL 710 RUL to RAL 712 RUL to RUL 714 This document is consistent with the rule that a Header cannot be 715 inserted or removed on the fly inside an IPv6 packet that is being 716 routed. This is a fundamental precept of the IPv6 architecture as 717 outlined in [RFC8200]. 719 As the rank information in the RPI artifact is changed at each hop, 720 it will typically be zero when it arrives at the DODAG root. The 721 DODAG root MUST force it to zero when passing the packet out to the 722 Internet. The Internet will therefore not see any SenderRank 723 information. 725 Despite being legal to leave the RPI artifact in place, an 726 intermediate router that needs to add an extension header (e.g. RH3 727 or RPL Option) MUST still encapsulate the packet in an (additional) 728 outer IP header. The new header is placed after this new outer IP 729 header. 731 A corollary is that an RH3 or RPL Option can only be removed by an 732 intermediate router if it is placed in an encapsulating IPv6 Header, 733 which is addressed TO the intermediate router. When it does so, the 734 whole encapsulating header must be removed. (A replacement may be 735 added). This sometimes can result in outer IP headers being 736 addressed to the next hop router using link-local address. 738 Both the RPL Option and the RH3 headers may be modified in very 739 specific ways by routers on the path of the packet without the need 740 to add and remove an encapsulating header. Both headers were 741 designed with this modification in mind, and both the RPL RH3 and the 742 RPL Option are marked mutable but recoverable: so an IPsec AH 743 security header can be applied across these headers, but it can not 744 secure the values which mutate. 746 The RPI MUST be present in every single RPL data packet. 748 Prior to [RFC8138], there was significant interest in creating an 749 exception to this rule and removing the RPI for downward flows in 750 non-storing mode. This exception covered a very small number of 751 cases, and caused significant interoperability challenges while 752 adding significant in the code and tests. The ability to compress 753 the RPI down to three bytes or less removes much of the pressure to 754 optimize this any further [I-D.ietf-anima-autonomic-control-plane]. 756 The earlier examples are more extensive to make sure that the process 757 is clear, while later examples are more concise. 759 The uses cases are delineated based on the following requirements: 761 The RPI has to be in every packet that traverses the LLN. 763 - Because of the above requirement, packets from the Internet have 764 to be encapsulated. 766 - A Header cannot be inserted or removed on the fly inside an IPv6 767 packet that is being routed. 769 - Extension headers may not be added or removed except by the 770 sender or the receiver. 772 - RPI and RH3 headers may be modified by routers on the path of 773 the packet without the need to add and remove an encapsulating 774 header. 776 - an RH3 or RPL Option can only be removed by an intermediate 777 router if it is placed in an encapsulating IPv6 Header, which is 778 addressed to the intermediate router. 780 - Non-storing mode requires downstream encapsulation by root for 781 RH3. 783 The uses cases are delineated based on the following assumptions: 785 This document assumes that the LLN is using the no-drop RPI Option 786 Type (0x23). 788 - Each IPv6 node (including Internet routers) obeys [RFC8200], so 789 that 0x23 RPI Option Type can be safely inserted. 791 - All 6LRs obey [RFC8200]. 793 - The RPI is ignored at the IPv6 dst node (RUL). 795 - In the uses cases, we assume that the RAL supports IP-in-IP 796 encapsulation. 798 - In the uses cases, we dont assume that the RUL supports IP-in-IP 799 encapsulation. 801 - For traffic leaving a RUL, if the RUL adds an opaque RPI then 802 the description of the RAL applies. 804 - The description for RALs applies to RAN in general. 806 - Non-constrained uses of RPL are not in scope of this document. 808 - Compression is based on [RFC8138]. 810 - The flow label [RFC6437] is not needed in RPL. 812 7. Storing mode 814 In storing mode (SM) (fully stateful), the sender can determine if 815 the destination is inside the LLN by looking if the destination 816 address is matched by the DIO's Prefix Information Option (PIO) 817 option. 819 The following table (Figure 7) itemizes which headers are needed in 820 each of the following scenarios. It indicates whether an IPv6-in- 821 IPv6 header must be added and what destination it must be addressed 822 to: (1) the final destination (the RAL node that is the target 823 (tgt)), (2) the "root", or (3) the 6LR parent of a RUL. 825 In cases where no IPv6-in-IPv6 header is needed, the column states as 826 "No". If the IPv6-in-IPv6 header is needed, the column shows "must". 828 In all cases, the RPI is needed, since it identifies inconsistencies 829 (loops) in the routing topology. In general, the RH3 is not needed 830 because it is not used in storing mode. However, there is one 831 scenario (from the root to the RUL in SM) where the RH3 can be used 832 to indicate the RUL (Figure 11). 834 The leaf can be a router 6LR or a host, both indicated as 6LN. The 835 root refers to the 6LBR (see Figure 6). 837 +---------------------+--------------+------------+----------------+ 838 | Interaction between | Use Case |IPv6-in-IPv6|IPv6-in-IPv6 dst| 839 +---------------------+--------------+------------+----------------+ 840 | | RAL to root | No | No | 841 + +--------------+------------+----------------+ 842 | Leaf - Root | root to RAL | No | No | 843 + +--------------+------------+----------------+ 844 | | root to RUL | must | 6LR | 845 + +--------------+------------+----------------+ 846 | | RUL to root | must | root | 847 +---------------------+--------------+------------+----------------+ 848 | | RAL to Int | may | root | 849 + +--------------+------------+----------------+ 850 | Leaf - Internet | Int to RAL | must | RAL (tgt) | 851 + +--------------+------------+----------------+ 852 | | RUL to Int | must | root | 853 + +--------------+------------+----------------+ 854 | | Int to RUL | must | 6LR | 855 +---------------------+--------------+------------+----------------+ 856 | | RAL to RAL | No | No | 857 | Leaf - Leaf +--------------+------------+----------------+ 858 | | RAL to RUL | No(up) | 6LR | 859 | + +------------+----------------+ 860 | | | must(down) | 6LR | 861 | +--------------+------------+----------------+ 862 | | RUL to RAL | must(up) | root | 863 | | +------------+----------------+ 864 | | | must(down) | RAL | 865 | +--------------+------------+----------------+ 866 | | RUL to RUL | must(up) | root | 867 | | +------------+----------------+ 868 | | | must(down) | 6LR | 869 |---------------------+--------------+------------+----------------+ 871 Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode. 873 7.1. Storing Mode: Interaction between Leaf and Root 875 In this section is described the communication flow in storing mode 876 (SM) between, 878 RAL to root 880 root to RAL 882 RUL to root 884 root to RUL 886 7.1.1. SM: Example of Flow from RAL to Root 888 In storing mode, RFC 6553 (RPI) is used to send RPL Information 889 instanceID and rank information. 891 In this case the flow comprises: 893 RAL (6LN) --> 6LR_i --> root(6LBR) 895 For example, a communication flow could be: Node F (6LN) --> Node D 896 (6LR_i) --> Node B (6LR_i)--> Node A root(6LBR) 898 The RAL (Node F) inserts the RPI, and sends the packet to 6LR (Node 899 D) which decrements the rank in the RPI and sends the packet up. 900 When the packet arrives at 6LBR (Node A), the RPI is removed and the 901 packet is processed. 903 No IPv6-in-IPv6 header is required. 905 The RPI can be removed by the 6LBR because the packet is addressed to 906 the 6LBR. The RAL must know that it is communicating with the 6LBR 907 to make use of this scenario. The RAL can know the address of the 908 6LBR because it knows the address of the root via the DODAGID in the 909 DIO messages. 911 The Figure 8 summarizes what headers are needed for this use case. 913 +-----------+-----+-------+------+ 914 | Header | RAL | 6LR_i | 6LBR | 915 | | src | | dst | 916 +-----------+-----+-------+------+ 917 | Added | RPI | -- | -- | 918 | headers | | | | 919 +-----------+-----+-------+------+ 920 | Modified | -- | RPI | -- | 921 | headers | | | | 922 +-----------+-----+-------+------+ 923 | Removed | -- | -- | RPI | 924 | headers | | | | 925 +-----------+-----+-------+------+ 926 | Untouched | -- | -- | -- | 927 | headers | | | | 928 +-----------+-----+-------+------+ 930 Figure 8: SM: Summary of the use of headers from RAL to root 932 7.1.2. SM: Example of Flow from Root to RAL 934 In this case the flow comprises: 936 root (6LBR) --> 6LR_i --> RAL (6LN) 938 For example, a communication flow could be: Node A root(6LBR) --> 939 Node B (6LR_i) --> Node D (6LR_i) --> Node F (6LN) 941 In this case the 6LBR inserts RPI and sends the packet down, the 6LR 942 is going to increment the rank in RPI (it examines the RPLInstanceID 943 to identify the right forwarding table), the packet is processed in 944 the RAL and the RPI removed. 946 No IPv6-in-IPv6 header is required. 948 The Figure 9 summarizes what headers are needed for this use case. 950 +-----------+------+-------+-----+ 951 | Header | 6LBR | 6LR_i | RAL | 952 | | src | | dst | 953 +-----------+------+-------+-----+ 954 | Added | RPI | -- | -- | 955 | headers | | | | 956 +-----------+------+-------+-----+ 957 | Modified | -- | RPI | -- | 958 | headers | | | | 959 +-----------+------+-------+-----+ 960 | Removed | -- | -- | RPI | 961 | headers | | | | 962 +-----------+------+-------+-----+ 963 | Untouched | -- | -- | -- | 964 | headers | | | | 965 +-----------+------+-------+-----+ 967 Figure 9: SM: Summary of the use of headers from root to RAL 969 7.1.3. SM: Example of Flow from Root to RUL 971 In this case the flow comprises: 973 root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 975 For example, a communication flow could be: Node A (6LBR) --> Node B 976 (6LR_i) --> Node E (6LR_n) --> Node G (RUL) 978 6LR_i (Node B) represents the intermediate routers from the source 979 (6LBR) to the destination (RUL), 1 <= i <= n, where n is the total 980 number of routers (6LR) that the packet goes through from the 6LBR 981 (Node A) to the RUL (Node G). 983 The 6LBR will insert an RPI, encapsulated in a IPv6-in-IPv6 header. 984 The IPv6-in-IPv6 header is addressed to the 6LR parent of the RUL 985 (6LR_n). The 6LR parent of the RUL removes the header and sends the 986 packet to the RUL. 988 The Figure 10 summarizes what headers are needed for this use case. 990 +-----------+---------+---------+---------+-----+ 991 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 992 | | src | | | dst | 993 +-----------+---------+---------+---------+-----+ 994 | Added | IP6-IP6 | -- | -- | -- | 995 | headers | (RPI) | | | | 996 +-----------+---------+---------+---------+-----+ 997 | Modified | -- | | -- | -- | 998 | headers | | RPI | | | 999 +-----------+---------+---------+---------+-----+ 1000 | Removed | -- | -- | IP6-IP6 | -- | 1001 | headers | | | (RPI) | | 1002 +-----------+---------+---------+---------+-----+ 1003 | Untouched | -- | -- | -- | -- | 1004 | headers | | | | | 1005 +-----------+---------+---------+---------+-----+ 1007 Figure 10: SM: Summary of the use of headers from root to RUL 1009 IP-in-IP encapsulation MAY be avoided for Root to RUL communication. 1010 In SM, it can be replaced by a loose SRH header that indicates the 1011 RUL, in which case the packet is routed to the 6LR as a normal SM 1012 operation, then the 6LR forwards to the RUL based on the SRH, and the 1013 RUL ignores both the consumed SRH and the RPI, as in Non-Storing 1014 Mode. 1016 The Figure 11 summarizes what headers are needed for this scenario. 1018 +-----------+----------+--------------+----------------+----------+ 1019 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 1020 | | src | i=(1,..,n-1) | | dst | 1021 | | | | | | 1022 +-----------+----------+--------------+----------------+----------+ 1023 | Added | RPI, RH3 | -- | -- | -- | 1024 | headers | | | | | 1025 +-----------+----------+--------------+----------------+----------+ 1026 | Modified | -- | RPI | RPI | -- | 1027 | headers | | | RH3(consumed) | | 1028 +-----------+----------+--------------+----------------+----------+ 1029 | Removed | -- | -- | -- | -- | 1030 | headers | | | | | 1031 +-----------+----------+--------------+----------------+----------+ 1032 | Untouched | -- | -- | -- | RPI, RH3 | 1033 | headers | | | | (both | 1034 | | | | | ignored) | 1035 +-----------+----------+--------------+----------------+----------+ 1037 Figure 11: SM: Summary of the use of headers from root to RUL without 1038 encapsulation 1040 7.1.4. SM: Example of Flow from RUL to Root 1042 In this case the flow comprises: 1044 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) 1046 For example, a communication flow could be: Node G (RUL) --> Node E 1047 (6LR_1)--> Node B (6LR_i)--> Node A root(6LBR) 1049 6LR_i represents the intermediate routers from the source (RUL) to 1050 the destination (6LBR), 1 <= i <= n, where n is the total number of 1051 routers (6LR) that the packet goes through from the RUL to the 6LBR. 1053 When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E), 1054 the 6LR_1 will insert an RPI, encapsulated in a IPv6-in-IPv6 header. 1055 The IPv6-in-IPv6 header is addressed to the root (Node A). The root 1056 removes the header and processes the packet. 1058 The Figure 12 shows the table that summarizes what headers are needed 1059 for this use case where the IPv6-in-IPv6 header is addressed to the 1060 root (Node A). 1062 +-----------+------+--------------+----------------+-----------------+ 1063 | Header | RUL | 6LR_1 | 6LR_i | 6LBR dst | 1064 | | src | | | | 1065 | | node | | | | 1066 +-----------+------+--------------+----------------+-----------------+ 1067 | Added | -- | IP6-IP6(RPI) | | -- | 1068 | headers | | | -- | | 1069 +-----------+------+--------------+----------------+-----------------+ 1070 | Modified | -- | -- | RPI | -- | 1071 | headers | | | | | 1072 +-----------+------+--------------+----------------+-----------------+ 1073 | Removed | -- | -- | --- | IP6-IP6(RPI) | 1074 | headers | | | | | 1075 +-----------+------+--------------+----------------+-----------------+ 1076 | Untouched | -- | -- | -- | -- | 1077 | headers | | | | | 1078 +-----------+------+--------------+----------------+-----------------+ 1080 Figure 12: SM: Summary of the use of headers from RUL to root. 1082 7.2. SM: Interaction between Leaf and Internet. 1084 In this section is described the communication flow in storing mode 1085 (SM) between, 1087 RAL to Internet 1089 Internet to RAL 1091 RUL to Internet 1093 Internet to RUL 1095 7.2.1. SM: Example of Flow from RAL to Internet 1097 In this case the flow comprises: 1099 RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet 1101 For example, the communication flow could be: Node F (RAL) --> Node D 1102 (6LR_i)--> Node B (6LR_i)--> Node A root(6LBR) --> Internet 1104 6LR_i represents the intermediate routers from the source (RAL) to 1105 the root (6LBR), 1 <= i <= n, where n is the total number of routers 1106 (6LR) that the packet goes through from the RAL to the 6LBR. 1108 RPL information from RFC 6553 may go out to Internet as it will be 1109 ignored by nodes which have not been configured to be RPI aware. No 1110 IPv6-in-IPv6 header is required. 1112 On the other hand, the RAL may insert the RPI encapsulated in a IPv6- 1113 in-IPv6 header to the root. Thus, the root removes the RPI and send 1114 the packet to the Internet. 1116 No IPv6-in-IPv6 header is required. 1118 Note: In this use case, it is used a node as a leaf, but this use 1119 case can be also applicable to any RPL-aware-node type (e.g. 6LR) 1121 The Figure 13 summarizes what headers are needed for this use case 1122 when there is no encapsulation. The Figure 14 summarizes what 1123 headers are needed when encapsulation to the root takes place. 1125 +-----------+-----+-------+------+-----------+ 1126 | Header | RAL | 6LR_i | 6LBR | Internet | 1127 | | src | | | dst | 1128 +-----------+-----+-------+------+-----------+ 1129 | Added | RPI | -- | -- | -- | 1130 | headers | | | | | 1131 +-----------+-----+-------+------+-----------+ 1132 | Modified | -- | RPI | -- | -- | 1133 | headers | | | | | 1134 +-----------+-----+-------+------+-----------+ 1135 | Removed | -- | -- | -- | -- | 1136 | headers | | | | | 1137 +-----------+-----+-------+------+-----------+ 1138 | Untouched | -- | -- | RPI | RPI | 1139 | headers | | | | (Ignored) | 1140 +-----------+-----+-------+------+-----------+ 1142 Figure 13: SM: Summary of the use of headers from RAL to Internet 1143 with no encapsulation 1145 +-----------+----------+--------------+--------------+--------------+ 1146 | Header | RAL | 6LR_i | 6LBR | Internet dst | 1147 | | src | | | | 1148 +-----------+----------+--------------+--------------+--------------+ 1149 | Added |IP6-IP6 | -- | -- | -- | 1150 | headers | (RPI) | | | | 1151 +-----------+----------+--------------+--------------+--------------+ 1152 | Modified | -- | RPI | -- | -- | 1153 | headers | | | | | 1154 +-----------+----------+--------------+--------------+--------------+ 1155 | Removed | -- | -- |IP6-IP6(RPI) | -- | 1156 | headers | | | | | 1157 +-----------+----------+--------------+--------------+--------------+ 1158 | Untouched | -- | -- | -- | -- | 1159 | headers | | | | | 1160 +-----------+----------+--------------+--------------+--------------+ 1162 Figure 14: SM: Summary of the use of headers from RAL to Internet 1163 with encapsulation to the root (6LBR). 1165 7.2.2. SM: Example of Flow from Internet to RAL 1167 In this case the flow comprises: 1169 Internet --> root (6LBR) --> 6LR_i --> RAL (6LN) 1171 For example, a communication flow could be: Internet --> Node A 1172 root(6LBR) --> Node B (6LR_1) --> Node D (6LR_n) --> Node F (RAL) 1174 When the packet arrives from Internet to 6LBR the RPI is added in a 1175 outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination address 1176 set to the RAL) and sent to 6LR, which modifies the rank in the RPI. 1177 When the packet arrives at the RAL the RPI is removed and the packet 1178 processed. 1180 The Figure 15 shows the table that summarizes what headers are needed 1181 for this use case. 1183 +-----------+----------+--------------+--------------+--------------+ 1184 | Header | Internet | 6LBR | 6LR_i | RAL dst | 1185 | | src | | | | 1186 +-----------+----------+--------------+--------------+--------------+ 1187 | Added | -- | IP6-IP6(RPI) | -- | -- | 1188 | headers | | | | | 1189 +-----------+----------+--------------+--------------+--------------+ 1190 | Modified | -- | -- | RPI | -- | 1191 | headers | | | | | 1192 +-----------+----------+--------------+--------------+--------------+ 1193 | Removed | -- | -- | -- | IP6-IP6(RPI) | 1194 | headers | | | | | 1195 +-----------+----------+--------------+--------------+--------------+ 1196 | Untouched | -- | -- | -- | -- | 1197 | headers | | | | | 1198 +-----------+----------+--------------+--------------+--------------+ 1200 Figure 15: SM: Summary of the use of headers from Internet to RAL. 1202 7.2.3. SM: Example of Flow from RUL to Internet 1204 In this case the flow comprises: 1206 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet 1208 For example, a communication flow could be: Node G (RUL)--> Node E 1209 (6LR_1)--> Node B (6lR_i) --> Node A root(6LBR) --> Internet 1211 The node 6LR_1 (i=1) will add an IPv6-in-IPv6(RPI) header addressed 1212 to the root such that the root can remove the RPI before passing 1213 upwards. In the intermediate 6LR, the rank in the RPI is modified. 1215 The originating node will ideally leave the IPv6 flow label as zero 1216 so that the packet can be better compressed through the LLN. The 1217 6LBR will set the flow label of the packet to a non-zero value when 1218 sending to the Internet, for details check [RFC6437]. 1220 The Figure 16 shows the table that summarizes what headers are needed 1221 for this use case. 1223 +---------+-------+------------+-------------+-------------+--------+ 1224 | Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet| 1225 | | src | | [i=2,...,n] | | dst | 1226 | | node | | | | | 1227 | | (RUL) | | | | | 1228 +---------+-------+------------+-------------+-------------+--------+ 1229 | Added | -- |IP6-IP6(RPI)| -- | -- | -- | 1230 | headers | | | | | | 1231 +---------+-------+------------+-------------+-------------+--------+ 1232 | Modified| -- | -- | RPI | -- | -- | 1233 | headers | | | | | | 1234 +---------+-------+------------+-------------+-------------+--------+ 1235 | Removed | -- | -- | -- | IP6-IP6(RPI)| -- | 1236 | headers | | | | | | 1237 +---------+-------+------------+-------------+-------------+--------+ 1238 |Untouched| -- | -- | -- | -- | -- | 1239 | headers | | | | | | 1240 +---------+-------+------------+-------------+-------------+--------+ 1242 Figure 16: SM: Summary of the use of headers from RUL to Internet. 1244 7.2.4. SM: Example of Flow from Internet to RUL. 1246 In this case the flow comprises: 1248 Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1250 For example, a communication flow could be: Internet --> Node A 1251 root(6LBR) --> Node B (6LR_i)--> Node E (6LR_n) --> Node G (RUL) 1253 The 6LBR will have to add an RPI within an IPv6-in-IPv6 header. The 1254 IPv6-in-IPv6 is addressed to the 6LR parent of the RUL. 1256 Further details about this are mentioned in 1257 [I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN 1258 acting as a plain host and not being aware of RPL. 1260 The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to 1261 zero in order to aid in compression [RFC8138][RFC6437]. 1263 The Figure 17 shows the table that summarizes what headers are needed 1264 for this use case. 1266 +---------+-------+------------+--------------+-------------+-------+ 1267 | Header |Inter- | 6LBR | 6LR_i | 6LR_n | RUL | 1268 | | net | |[i=1,..,n-1] | | dst | 1269 | | src | | | | | 1270 | | | | | | | 1271 +---------+-------+------------+--------------+-------------+-------+ 1272 | Inserted| -- |IP6-IP6(RPI)| -- | -- | -- | 1273 | headers | | | | | | 1274 +---------+-------+------------+--------------+-------------+-------+ 1275 | Modified| -- | -- | RPI | -- | -- | 1276 | headers | | | | | | 1277 +---------+-------+------------+--------------+-------------+-------+ 1278 | Removed | -- | -- | -- | IP6-IP6(RPI)| -- | 1279 | headers | | | | | | 1280 +---------+-------+------------+--------------+-------------+-------+ 1281 |Untouched| -- | -- | -- | -- | -- | 1282 | headers | | | | | | 1283 +---------+-------+------------+--------------+-------------+-------+ 1285 Figure 17: SM: Summary of the use of headers from Internet to RUL. 1287 7.3. SM: Interaction between Leaf and Leaf 1289 In this section is described the communication flow in storing mode 1290 (SM) between, 1292 RAL to RAL 1294 RAL to RUL 1296 RUL to RAL 1298 RUL to RUL 1300 7.3.1. SM: Example of Flow from RAL to RAL 1302 In [RFC6550] RPL allows a simple one-hop optimization for both 1303 storing and non-storing networks. A node may send a packet destined 1304 to a one-hop neighbor directly to that node. See section 9 in 1305 [RFC6550]. 1307 When the nodes are not directly connected, then in storing mode, the 1308 flow comprises: 1310 RAL src (6LN) --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> RAL 1311 dst (6LN) 1312 For example, a communication flow could be: Node F (RAL src)--> Node 1313 D (6LR_ia)--> Node B (6LR_x) --> Node E (6LR_id) --> Node H (RAL dst) 1315 6LR_ia (Node D) represents the intermediate routers from source to 1316 the common parent (6LR_x) (Node B), 1 <= ia <= n, where n is the 1317 total number of routers (6LR) that the packet goes through from RAL 1318 (Node F) to the common parent 6LR_x (Node B). 1320 6LR_id (Node E) represents the intermediate routers from the common 1321 parent (6LR_x) (Node B) to destination RAL (Node H), 1 <= id <= m, 1322 where m is the total number of routers (6LR) that the packet goes 1323 through from the common parent (6LR_x) to destination RAL (Node H). 1325 It is assumed that the two nodes are in the same RPL domain (that 1326 they share the same DODAG root). At the common parent (Node B), the 1327 direction flag ('O' flag) of the RPI is changed (from decreasing 1328 ranks to increasing ranks). 1330 While the 6LR nodes will update the RPI, no node needs to add or 1331 remove the RPI, so no IPv6-in-IPv6 headers are necessary. 1333 The Figure 18 summarizes what headers are needed for this use case. 1335 +-----------+-----+--------+---------+--------+-----+ 1336 | Header | RAL | 6LR_ia | 6LR_x | 6LR_id | RAL | 1337 | | src | | (common | | dst | 1338 | | | | parent) | | | 1339 +-----------+-----+--------+---------+--------+-----+ 1340 | Added | RPI | -- | -- | -- | -- | 1341 | headers | | | | | | 1342 +-----------+-----+--------+---------+--------+-----+ 1343 | Modified | -- | RPI | RPI | RPI | -- | 1344 | headers | | | | | | 1345 +-----------+-----+--------+---------+--------+-----+ 1346 | Removed | -- | -- | -- | -- | RPI | 1347 | headers | | | | | | 1348 +-----------+-----+--------+---------+--------+-----+ 1349 | Untouched | -- | -- | -- | -- | -- | 1350 | headers | | | | | | 1351 +-----------+-----+--------+---------+--------+-----+ 1353 Figure 18: SM: Summary of the Use of Headers from RAL to RAL 1355 7.3.2. SM: Example of Flow from RAL to RUL 1357 In this case the flow comprises: 1359 RAL src (6LN) --> 6LR_ia --> common parent (6LBR - The root-) --> 1360 6LR_id --> RUL (IPv6 dst node) 1362 For example, a communication flow could be: Node F (RAL)--> Node D 1363 --> Node B --> Node E --> Node G (RUL) 1365 6LR_ia represents the intermediate routers from source (RAL) to the 1366 common parent (the Root), 1 <= ia <= n, where n is the total number 1367 of routers (6LR) that the packet goes through from RAL to the Root. 1369 6LR_id (Node E) represents the intermediate routers from the Root 1370 (Node B) to destination RUL (Node G). In this case, 1 <= id <= m, 1371 where m is the total number of routers (6LR) that the packet goes 1372 through from the Root down to the destination RUL. 1374 In this case, the packet from the RAL goes to 6LBR because the route 1375 to the RUL is not injected into the RPL-SM. Thus, the RAL inserts an 1376 RPI (RPI1) addressed to the root(6LBR). The root removes the RPI1 1377 and inserts an RPI2 encapsulated to the 6LR parent of the RUL, which 1378 removes the RPI2 before pasing the packet to the RUL. 1380 The Figure 19 summarizes what headers are needed for this use case. 1382 +----------+-------+-------+---------+---------+---------+---------+ 1383 | Header | RAL |6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL | 1384 | | src | | | | | dst | 1385 | | node | | | | | node | 1386 +----------+-------+-------+---------+---------+---------+---------+ 1387 | Added | | | IP6-IP6 | -- | -- | -- | 1388 | headers | RPI1 | -- | (RPI2) | | | | 1389 | | | | | | | | 1390 +----------+-------+-------+---------+---------+---------+---------+ 1391 | Modified | -- | | -- | | | -- | 1392 | headers | | RPI1 | | RPI2 | -- | | 1393 | | | | | | | | 1394 +----------+-------+-------+---------+---------+---------+---------+ 1395 | Removed | -- | -- | | -- | IP6-IP6 | -- | 1396 | headers | | | -- | | (RPI2) | | 1397 | | | | | | | | 1398 +----------+-------+-------+---------+---------+---------+---------+ 1399 |Untouched | -- | -- | RPI1 | RPI1 | RPI1 | RPI1 | 1400 | headers | | | | | |(Ignored)| 1401 | | | | | | | | 1402 +----------+-------+-------+---------+---------+---------+---------+ 1404 Figure 19: SM: Summary of the Use of Headers from RAL to RUL 1406 7.3.3. SM: Example of Flow from RUL to RAL 1408 In this case the flow comprises: 1410 RUL (IPv6 src node) --> 6LR_ia --> 6LBR --> 6LR_id --> RAL dst (6LN) 1412 For example, a communication flow could be: Node G (RUL)--> Node E 1413 --> Node B --> Node A --> Node B --> Node D --> Node F (RAL) 1415 6LR_ia (Node E) represents the intermediate routers from source (RUL) 1416 (Node G) to the root (Node A). In this case, 1 <= ia <= n, where n 1417 is the total number of routers (6LR) that the packet goes through 1418 from source to the root. 1420 6LR_id represents the intermediate routers from the root (Node A) to 1421 destination RAL (Node F). In this case, 1 <= id <= m, where m is the 1422 total number of routers (6LR) that the packet goes through from the 1423 root to the destination RAL. 1425 The 6LR_ia (ia=1) (Node E) receives the packet from the RUL (Node G) 1426 and inserts the RPI (RPI1) encapsulated in a IPv6-in-IPv6 header to 1427 the root. The root removes the outer header including the RPI (RPI1) 1428 and inserts a new RPI (RPI2) addressed to the destination RAL (Node 1429 F). 1431 The Figure 20 shows the table that summarizes what headers are needed 1432 for this use case. 1434 +-----------+------+---------+---------+---------+---------+---------+ 1435 | Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL | 1436 | | src | | | | | dst | 1437 | | node | | | | | node | 1438 +-----------+------+---------+---------+---------+---------+---------+ 1439 | Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- | 1440 | headers | | (RPI1) | | (RPI2) | | | 1441 | | | | | | | | 1442 +-----------+------+---------+---------+---------+---------+---------+ 1443 | Modified | -- | | | -- | | -- | 1444 | headers | | -- | RPI1 | | RPI2 | | 1445 | | | | | | | | 1446 +-----------+------+---------+---------+---------+---------+---------+ 1447 | Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 | 1448 | headers | | -- | | (RPI1) | | (RPI2) | 1449 | | | | | | | | 1450 +-----------+------+---------+---------+---------+---------+---------+ 1451 | Untouched | -- | -- | -- | -- | -- | -- | 1452 | headers | | | | | | | 1453 +-----------+------+---------+---------+---------+---------+---------+ 1455 Figure 20: SM: Summary of the use of headers from RUL to RAL. 1457 7.3.4. SM: Example of Flow from RUL to RUL 1459 In this case the flow comprises: 1461 RUL (IPv6 src node)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id --> RUL 1462 (IPv6 dst node) 1464 For example, a communication flow could be: Node G (RUL src)--> Node 1465 E --> Node B --> Node A (root) --> Node C --> Node J (RUL dst) 1467 Internal nodes 6LR_ia (e.g: Node E or Node B) is the intermediate 1468 router from the RUL source (Node G) to the root (6LBR) (Node A). In 1469 this case, 1 <= ia <= n, where n is the total number of routers (6LR) 1470 that the packet goes through from the RUL to the root. 6LR_1 refers 1471 when ia=1. 1473 6LR_id (Node C) represents the intermediate routers from the root 1474 (Node A) to the destination RUL dst node (Node J). In this case, 1 1475 <= id <= m, where m is the total number of routers (6LR) that the 1476 packet goes through from the root to destination RUL. 1478 The RPI is ignored at the RUL dst node. 1480 The 6LR_1 (Node E) receives the packet from the RUL (Node G) and 1481 inserts the RPI (RPI), encapsulated in an IPv6-in-IPv6 header 1482 directed to the root. The root removes the outer header including 1483 the RPI (RPI1) and inserts a new RPI (RPI2) addressed to the 6LR 1484 father of the RUL. 1486 The Figure 21 shows the table that summarizes what headers are needed 1487 for this use case. 1489 +---------+----+-------------+--------+---------+--------+-------+---+ 1490 | Header |RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id |6LR_n |RUL| 1491 | |src | | | | | |dst| 1492 | | | | | | | | | 1493 +---------+----+-------------+--------+---------+--------+-------+---+ 1494 | Added | -- |IP6-IP6(RPI1)| -- | IP6-IP6 | -- | -- | --| 1495 | Headers | | | | (RPI2) | | | | 1496 +---------+----+-------------+--------+---------+--------+-------+---+ 1497 |Modified | -- | -- | | -- | | -- | --| 1498 |headers | | | RPI1 | | RPI2 | | | 1499 +---------+----+-------------+--------+---------+--------+-------+---+ 1500 | Removed | -- | -- | -- | IP6-IP6 | -- |IP6-IP6| --| 1501 | headers | | | | (RPI1) | | (RPI2)| | 1502 +---------+----+-------------+--------+---------+--------+-------+---+ 1503 |Untouched| -- | -- | -- | -- | -- | -- | --| 1504 | headers | | | | | | | | 1505 +---------+----+-------------+--------+---------+--------+-------+---+ 1507 Figure 21: SM: Summary of the use of headers from RUL to RUL 1509 8. Non Storing mode 1511 In Non Storing Mode (Non-SM) (fully source routed), the 6LBR (DODAG 1512 root) has complete knowledge about the connectivity of all DODAG 1513 nodes, and all traffic flows through the root node. Thus, there is 1514 no need for all nodes to know about the existence of RPL-unaware 1515 nodes. Only the 6LBR needs to act if compensation is necessary for 1516 not-RPL aware receivers. 1518 The table (Figure 22) summarizes what headers are needed in the 1519 following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6 1520 header are to be inserted. The last column depicts the target 1521 destination of the IPv6-in-IPv6 header: 6LN (indicated by "RAL"), 6LR 1522 (parent of a RUL) or the root. In cases where no IPv6-in-IPv6 header 1523 is needed, the column indicates "No". There is no expectation on RPL 1524 that RPI can be omitted, because it is needed for routing, quality of 1525 service and compression. This specification expects that an RPI is 1526 always present. The term "may(up)" means that the IPv6-in-IPv6 1527 header may be necessary in the upwards direction. The term 1528 "must(up)" means that the IPv6-in-IPv6 header must be present in the 1529 upwards direction. The term "must(down)" means that the IPv6-in-IPv6 1530 header must be present in the downward direction. 1532 The leaf can be a router 6LR or a host, both indicated as 6LN 1533 (Figure 6). In the table (Figure 22) the (1) indicates a 6tisch case 1534 [RFC8180], where the RPI may still be needed for the RPLInstanceID to 1535 be available for priority/channel selection at each hop. 1537 The root always have to encapuslate on the way down 1539 +--- ------------+-------------+-----+-----+--------------+----------+ 1540 | Interaction | Use Case | RPI | RH3 | IPv6-in-IPv6 | IP-in-IP | 1541 | between | | | | | dst | 1542 +----------------+-------------+-----+-----+--------------+----------+ 1543 | | RAL to root | Yes | No | No | No | 1544 | +-------------+-----+-----+--------------+----------+ 1545 | Leaf - Root | root to RAL | Yes | Yes | No | No | 1546 | +-------------+-----+-----+--------------+----------+ 1547 | | root to RUL | Yes | Yes | must | 6LR | 1548 | | | (1) | | | | 1549 | +-------------+-----+-----+--------------+----------+ 1550 | | RUL to root | Yes | No | must | root | 1551 +----------------+-------------+-----+-----+--------------+----------+ 1552 | | RAL to Int | Yes | No | may(up) | root | 1553 | +-------------+-----+-----+--------------+----------+ 1554 |Leaf - Internet | Int to RAL | Yes | Yes | must | RAL | 1555 | +-------------+-----+-----+--------------+----------+ 1556 | | RUL to Int | Yes | No | must | root | 1557 | +-------------+-----+-----+--------------+----------+ 1558 | | Int to RUL | Yes | Yes | must | 6LR | 1559 +----------------+-------------+-----+-----+--------------+----------+ 1560 | | RAL to RAL | Yes | Yes | may(up) | root | 1561 | | | | +--------------+----------+ 1562 | | | | | must(down) | RAL | 1563 | Leaf - Leaf +-------------+-----+-----+--------------+----------+ 1564 | | RAL to RUL | Yes | Yes | may(up) | root | 1565 | | | | +--------------+----------+ 1566 | | | | | must(down) | 6LR | 1567 | +-------------+-----+-----+--------------+----------+ 1568 | | RUL to RAL | Yes | Yes | must(up) | root | 1569 | | | | +--------------+----------+ 1570 | | | | | must(down) | RAL | 1571 | +-------------+-----+-----+--------------+----------+ 1572 | | RUL to RUL | Yes | Yes | must(up) | root | 1573 | | | | +--------------+----------+ 1574 | | | | | must(down) | 6LR | 1575 +----------------+-------------+-----+-----+--------------+----------+ 1577 Figure 22: Table that shows headers needed in Non-Storing mode: RPI, 1578 RH3, IPv6-in-IPv6 encapsulation. 1580 8.1. Non-Storing Mode: Interaction between Leaf and Root 1582 In this section is described the communication flow in Non Storing 1583 Mode (Non-SM) between, 1585 RAL to root 1586 root to RAL 1588 RUL to root 1590 root to RUL 1592 8.1.1. Non-SM: Example of Flow from RAL to root 1594 In non-storing mode the leaf node uses default routing to send 1595 traffic to the root. The RPI must be included since it contains the 1596 rank information, which is used to avoid/detect loops. 1598 RAL (6LN) --> 6LR_i --> root(6LBR) 1600 For example, a communication flow could be: Node F --> Node D --> 1601 Node B --> Node A (root) 1603 6LR_i represents the intermediate routers from source to destination. 1604 In this case, 1 <= i <= n, where n is the total number of routers 1605 (6LR) that the packet goes through from source (RAL) to destination 1606 (6LBR). 1608 This situation is the same case as storing mode. 1610 The Figure 23 summarizes what headers are needed for this use case. 1612 +-----------+-----+-------+------+ 1613 | Header | RAL | 6LR_i | 6LBR | 1614 | | src | | dst | 1615 +-----------+-----+-------+------+ 1616 | Added | RPI | -- | -- | 1617 | headers | | | | 1618 +-----------+-----+-------+------+ 1619 | Modified | -- | RPI | -- | 1620 | headers | | | | 1621 +-----------+-----+-------+------+ 1622 | Removed | -- | -- | RPI | 1623 | headers | | | | 1624 +-----------+-----+-------+------+ 1625 | Untouched | -- | -- | -- | 1626 | headers | | | | 1627 +-----------+-----+-------+------+ 1629 Figure 23: Non-SM: Summary of the use of headers from RAL to root 1631 8.1.2. Non-SM: Example of Flow from root to RAL 1633 In this case the flow comprises: 1635 root (6LBR) --> 6LR_i --> RAL (6LN) 1637 For example, a communication flow could be: Node A (root) --> Node B 1638 --> Node D --> Node F 1640 6LR_i represents the intermediate routers from source to destination. 1641 In this case, 1 <= i <= n, where n is the total number of routers 1642 (6LR) that the packet goes through from source (6LBR) to destination 1643 (RAL). 1645 The 6LBR inserts an RH3, and an RPI. No IPv6-in-IPv6 header is 1646 necessary as the traffic originates with a RPL aware node, the 6LBR. 1647 The destination is known to be RPL-aware because the root knows the 1648 whole topology in non-storing mode. 1650 The Figure 24 summarizes what headers are needed for this use case. 1652 +-----------+----------+----------+----------+ 1653 | Header | 6LBR | 6LR_i | RAL | 1654 | | src | | dst | 1655 +-----------+----------+----------+----------+ 1656 | Added | RPI, RH3 | -- | -- | 1657 | headers | | | | 1658 +-----------+----------+----------+----------+ 1659 | Modified | -- | RPI, RH3 | -- | 1660 | headers | | | | 1661 +-----------+----------+----------+----------+ 1662 | Removed | -- | -- | RPI, RH3 | 1663 | headers | | | | 1664 +-----------+----------+----------+----------+ 1665 | Untouched | -- | -- | -- | 1666 | headers | | | | 1667 +-----------+----------+----------+----------+ 1669 Figure 24: Non-SM: Summary of the use of headers from root to RAL 1671 8.1.3. Non-SM: Example of Flow from root to RUL 1673 In this case the flow comprises: 1675 root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1677 For example, a communication flow could be: Node A (root) --> Node B 1678 --> Node E --> Node G (RUL) 1679 6LR_i represents the intermediate routers from source to destination. 1680 In this case, 1 <= i <= n, where n is the total number of routers 1681 (6LR) that the packet goes through from source (6LBR) to destination 1682 (RUL). 1684 In the 6LBR, the RH3 is added; it is then modified at each 1685 intermediate 6LR (6LR_1 and so on), and it is fully consumed in the 1686 last 6LR (6LR_n) but is left in place. When the RPI is added, the 1687 IPv6 node, which does not understand the RPI, will ignore it (per 1688 [RFC8200]); thus, encapsulation is not necessary. 1690 The Figure 25 depicts the table that summarizes what headers are 1691 needed for this use case. 1693 +-----------+----------+--------------+----------------+----------+ 1694 | Header | 6LBR | 6LR_i | 6LR_n | RUL | 1695 | | src | i=(1,..,n-1) | | dst | 1696 | | | | | | 1697 +-----------+----------+--------------+----------------+----------+ 1698 | Added | RPI, RH3 | -- | -- | -- | 1699 | headers | | | | | 1700 +-----------+----------+--------------+----------------+----------+ 1701 | Modified | -- | RPI, RH3 | RPI, | -- | 1702 | headers | | | RH3(consumed) | | 1703 +-----------+----------+--------------+----------------+----------+ 1704 | Removed | -- | -- | -- | -- | 1705 | headers | | | | | 1706 +-----------+----------+--------------+----------------+----------+ 1707 | Untouched | -- | -- | -- | RPI, RH3 | 1708 | headers | | | | (both | 1709 | | | | | ignored) | 1710 +-----------+----------+--------------+----------------+----------+ 1712 Figure 25: Non-SM: Summary of the use of headers from root to RUL 1714 8.1.4. Non-SM: Example of Flow from RUL to root 1716 In this case the flow comprises: 1718 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) dst 1720 For example, a communication flow could be: Node G --> Node E --> 1721 Node B --> Node A (root) 1723 6LR_i represents the intermediate routers from source to destination. 1724 In this case, 1 <= i <= n, where n is the total number of routers 1725 (6LR) that the packet goes through from source (RUL) to destination 1726 (6LBR). For example, 6LR_1 (i=1) is the router that receives the 1727 packets from the IPv6 node. 1729 In this case, the RPI is added by the first 6LR (6LR_1) (Node E), 1730 encapsulated in an IPv6-in-IPv6 header, and modified in the 1731 subsequent 6LRs in the flow. The RPI and the entire packet are 1732 consumed by the root. 1734 The Figure 26 shows the table that summarizes what headers are needed 1735 for this use case. 1737 +---------+----+-----------------+-----------------+-----------------+ 1738 | |RUL | | | | 1739 | Header |src | 6LR_1 | 6LR_i | 6LBR dst | 1740 | |node| | | | 1741 +---------+----+-----------------+-----------------+-----------------+ 1742 | Added | -- |IPv6-in-IPv6(RPI)| -- | -- | 1743 | headers | | | | | 1744 +---------+----+-----------------+-----------------+-----------------+ 1745 | Modified| -- | -- | RPI | -- | 1746 | headers | | | | | 1747 +---------+----+-----------------+-----------------+-----------------+ 1748 | Removed | -- | -- | -- |IPv6-in-IPv6(RPI)| 1749 | headers | | | | | 1750 +---------+----+-----------------+-----------------+-----------------+ 1751 |Untouched| -- | -- | -- | -- | 1752 | headers | | | | | 1753 +---------+----+-----------------+-----------------+-----------------+ 1755 Figure 26: Non-SM: Summary of the use of headers from RUL to root 1757 8.2. Non-Storing Mode: Interaction between Leaf and Internet 1759 This section will describe the communication flow in Non Storing Mode 1760 (Non-SM) between: 1762 RAL to Internet 1764 Internet to RAL 1766 RUL to Internet 1768 Internet to RUL 1770 8.2.1. Non-SM: Example of Flow from RAL to Internet 1772 In this case the flow comprises: 1774 RAL (6LN) src --> 6LR_i --> root (6LBR) --> Internet dst 1776 For example, a communication flow could be: Node F (RAL) --> Node D 1777 --> Node B --> Node A --> Internet 1779 6LR_i represents the intermediate routers from source to destination, 1780 1 <= i <= n, where n is the total number of routers (6LR) that the 1781 packet goes through from source (RAL) to 6LBR. 1783 In this case, the encapsulation from the RAL to the root is optional. 1784 The simplest case is when the RPI gets to the Internet (as the 1785 Figure 27 shows it), knowing that the Internet is going to ignore it. 1787 The IPv6 flow label should be set to zero to aid in compression 1788 [RFC8138], and the 6LBR will set it to a non-zero value when sending 1789 towards the Internet [RFC6437]. 1791 The Figure 27 summarizes what headers are needed for this use case 1792 when no encapsulation is used. The Figure 28 summarizes what headers 1793 are needed for this use case when encapsulation to the root is used. 1795 +-----------+-----+-------+------+-----------+ 1796 | Header | RAL | 6LR_i | 6LBR | Internet | 1797 | | src | | | dst | 1798 +-----------+-----+-------+------+-----------+ 1799 | Added | RPI | -- | -- | -- | 1800 | headers | | | | | 1801 +-----------+-----+-------+------+-----------+ 1802 | Modified | -- | RPI | -- | -- | 1803 | headers | | | | | 1804 +-----------+-----+-------+------+-----------+ 1805 | Removed | -- | -- | -- | -- | 1806 | headers | | | | | 1807 +-----------+-----+-------+------+-----------+ 1808 | Untouched | -- | -- | RPI | RPI | 1809 | headers | | | | (Ignored) | 1810 +-----------+-----+-------+------+-----------+ 1812 Figure 27: Non-SM: Summary of the use of headers from RAL to Internet 1813 with no encapsulation 1815 +-----------+--------------+--------------+--------------+----------+ 1816 | Header | RAL | 6LR_i | 6LBR | Internet | 1817 | | src | | | dst | 1818 +-----------+--------------+--------------+--------------+----------+ 1819 | Added | IPv6-in-IPv6 | -- | -- | -- | 1820 | headers | (RPI) | | | | 1821 +-----------+--------------+--------------+--------------+----------+ 1822 | Modified | -- | | -- | -- | 1823 | headers | | RPI | | | 1824 +-----------+--------------+--------------+--------------+----------+ 1825 | Removed | -- | -- | IPv6-in-IPv6 | -- | 1826 | headers | | | (RPI) | | 1827 +-----------+--------------+--------------+--------------+----------+ 1828 | Untouched | -- | -- | -- | -- | 1829 | headers | | | | | 1830 +-----------+--------------+--------------+--------------+----------+ 1832 Figure 28: Non-SM: Summary of the use of headers from RAL to Internet 1833 with encapsulation to the root 1835 8.2.2. Non-SM: Example of Flow from Internet to RAL 1837 In this case the flow comprises: 1839 Internet --> root (6LBR) --> 6LR_i --> RAL dst (6LN) 1841 For example, a communication flow could be: Internet --> Node A 1842 (root) --> Node B --> Node D --> Node F (RAL) 1844 6LR_i represents the intermediate routers from source to destination, 1845 1 <= i <= n, where n is the total number of routers (6LR) that the 1846 packet goes through from 6LBR to destination (RAL). 1848 The 6LBR must add an RH3 header. As the 6LBR will know the path and 1849 address of the target node, it can address the IPv6-in-IPv6 header to 1850 that node. The 6LBR will zero the flow label upon entry in order to 1851 aid compression [RFC8138]. 1853 The Figure 29 summarizes what headers are needed for this use case. 1855 +-----------+----------+--------------+--------------+--------------+ 1856 | Header | Internet | 6LBR | 6LR_i | RAL | 1857 | | src | | | dst | 1858 +-----------+----------+--------------+--------------+--------------+ 1859 | Added | -- | IPv6-in-IPv6 | -- | -- | 1860 | headers | | (RH3, RPI) | | | 1861 +-----------+----------+--------------+--------------+--------------+ 1862 | Modified | -- | -- | IPv6-in-IPv6 | -- | 1863 | headers | | | (RH3, RPI) | | 1864 +-----------+----------+--------------+--------------+--------------+ 1865 | Removed | -- | -- | -- | IPv6-in-IPv6 | 1866 | headers | | | | (RH3, RPI) | 1867 +-----------+----------+--------------+--------------+--------------+ 1868 | Untouched | -- | -- | -- | -- | 1869 | headers | | | | | 1870 +-----------+----------+--------------+--------------+--------------+ 1872 Figure 29: Non-SM: Summary of the use of headers from Internet to RAL 1874 8.2.3. Non-SM: Example of Flow from RUL to Internet 1876 In this case the flow comprises: 1878 RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet 1879 dst 1881 For example, a communication flow could be: Node G --> Node E --> 1882 Node B --> Node A --> Internet 1884 6LR_i are the intermediate routers from source to destination, 1 <= i 1885 <= n, where n is the total number of routers (6LRs) that the packet 1886 goes through from the source (RUL) to the 6LBR, e.g., 6LR_1 (i=1). 1888 In this case the flow label is recommended to be zero in the IPv6 1889 node. As RPL headers are added in the IPv6 node packet, the first 1890 6LR (6LR_1) will add an RPI inside a new IPv6-in-IPv6 header. The 1891 IPv6-in-IPv6 header will be addressed to the root. This case is 1892 identical to the storing-mode case (see Section 7.2.3). 1894 The Figure 30 shows the table that summarizes what headers are needed 1895 for this use case. 1897 +---------+----+-------------+--------------+--------------+--------+ 1898 | Header |RUL | 6LR_1 | 6LR_i | 6LBR |Internet| 1899 | |src | | [i=2,..,n] | | dst | 1900 | |node| | | | | 1901 +---------+----+-------------+--------------+--------------+--------+ 1902 | Added | -- |IP6-IP6(RPI) | -- | -- | -- | 1903 | headers | | | | | | 1904 +---------+----+-------------+--------------+--------------+--------+ 1905 | Modified| -- | -- | RPI | -- | -- | 1906 | headers | | | | | | 1907 +---------+----+-------------+--------------+--------------+--------+ 1908 | Removed | -- | -- | -- | IP6-IP6(RPI) | -- | 1909 | headers | | | | | | 1910 +---------+----+-------------+--------------+--------------+--------+ 1911 |Untouched| -- | -- | -- | -- | -- | 1912 | headers | | | | | | 1913 +---------+----+-------------+--------------+--------------+--------+ 1915 Figure 30: Non-SM: Summary of the use of headers from RUL to Internet 1917 8.2.4. Non-SM: Example of Flow from Internet to RUL 1919 In this case the flow comprises: 1921 Internet src --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node) 1923 For example, a communication flow could be: Internet --> Node A 1924 (root) --> Node B --> Node E --> Node G 1926 6LR_i represents the intermediate routers from source to destination, 1927 1 <= i <= n, where n is the total number of routers (6LR) that the 1928 packet goes through from 6LBR to RUL. 1930 The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The 1931 6LBR will know the path, and will recognize that the final node is 1932 not a RPL capable node as it will have received the connectivity DAO 1933 from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6 1934 header destination be the last 6LR. The 6LBR will set to zero the 1935 flow label upon entry in order to aid compression [RFC8138]. 1937 The Figure 31 shows the table that summarizes what headers are needed 1938 for this use case. 1940 +----------+--------+------------------+-----------+-----------+-----+ 1941 | Header |Internet| 6LBR | 6LR_i | 6LR_n | RUL | 1942 | | src | | | | dst | 1943 +----------+--------+------------------+-----------+-----------+-----+ 1944 | Added | -- | IP6-IP6(RH3,RPI) | -- | -- | -- | 1945 | headers | | | | | | 1946 +----------+--------+------------------+-----------+-----------+-----+ 1947 | Modified | -- | -- | IP6-IP6 | -- | -- | 1948 | headers | | | (RH3,RPI) | | | 1949 +----------+--------+------------------+-----------+-----------+-----+ 1950 | Removed | -- | -- | -- | IP6-IP6 | -- | 1951 | headers | | | | (RH3,RPI) | | 1952 +----------+--------+------------------+-----------+-----------+-----+ 1953 |Untouched | -- | -- | -- | -- | -- | 1954 | headers | | | | | | 1955 +----------+--------+------------------+-----------+-----------+-----+ 1957 Figure 31: Non-SM: Summary of the use of headers from Internet to 1958 RUL. 1960 8.3. Non-SM: Interaction between leaves 1962 In this section is described the communication flow in Non Storing 1963 Mode (Non-SM) between, 1965 RAL to RAL 1967 RAL to RUL 1969 RUL to RAL 1971 RUL to RUL 1973 8.3.1. Non-SM: Example of Flow from RAL to RAL 1975 In this case the flow comprises: 1977 RAL src --> 6LR_ia --> root (6LBR) --> 6LR_id --> RAL dst 1979 For example, a communication flow could be: Node F (RAL src)--> Node 1980 D --> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL 1981 dst) 1983 6LR_ia represents the intermediate routers from source to the root, 1 1984 <= ia <= n, where n is the total number of routers (6LR) that the 1985 packet goes through from RAL to the root. 1987 6LR_id represents the intermediate routers from the root to the 1988 destination, 1 <= id <= m, where m is the total number of the 1989 intermediate routers (6LR). 1991 This case involves only nodes in same RPL domain. The originating 1992 node will add an RPI to the original packet, and send the packet 1993 upwards. 1995 The originating node may put the RPI (RPI1) into an IPv6-in-IPv6 1996 header addressed to the root, so that the 6LBR can remove that 1997 header. If it does not, then the RPI1 is forwarded down from the 1998 root in the inner header to no avail. 2000 The 6LBR will need to insert an RH3 header, which requires that it 2001 add an IPv6-in-IPv6 header. It should be able to remove the 2002 RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to 2003 it. Otherwise, there may be an RPI buried inside the inner IP 2004 header, which should get ignored. The root inserts an RPI (RPI2) 2005 alongside the RH3. 2007 Networks that use the RPL P2P extension [RFC6997] are essentially 2008 non-storing DODAGs and fall into this scenario or scenario 2009 Section 8.1.2, with the originating node acting as 6LBR. 2011 The Figure 32 shows the table that summarizes what headers are needed 2012 for this use case when encapsulation to the root takes place. 2014 The Figure 33 shows the table that summarizes what headers are needed 2015 for this use case when there is no encapsulation to the root. Note 2016 that in the Modified headers row, going up in each 6LR_ia only the 2017 RPI1 is changed. Going down, in each 6LR_id the IPv6 header is 2018 swapped with the SRH so both are changed alongside with the RPI2. 2020 +---------+-------+----------+------------+----------+------------+ 2021 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL | 2022 | | src | | | | dst | 2023 +---------+-------+----------+------------+----------+------------+ 2024 | Added |IP6-IP6| | IP6-IP6 | -- | -- | 2025 | headers |(RPI1) | -- |(RH3-> RAL, | | | 2026 | | | | RPI2) | | | 2027 +---------+-------+----------+------------+----------+------------+ 2028 | Modified| -- | | -- | IP6-IP6 | -- | 2029 | headers | | RPI1 | |(RH3,RPI2)| | 2030 +---------+-------+----------+------------+----------+------------+ 2031 | Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | 2032 | headers | | | (RPI1) | | (RH3, | 2033 | | | | | | RPI2) | 2034 +---------+-------+----------+------------+----------+------------+ 2035 |Untouched| -- | -- | -- | -- | -- | 2036 | headers | | | | | | 2037 +---------+-------+----------+------------+----------+------------+ 2039 Figure 32: Non-SM: Summary of the Use of Headers from RAL to RAL with 2040 encapsulation to the root. 2042 +-----------+------+--------+---------+---------+---------+ 2043 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL | 2044 +-----------+------+--------+---------+---------+---------+ 2045 | Inserted | RPI1 | -- | IP6-IP6 | -- | -- | 2046 | headers | | | (RH3, | | | 2047 | | | | RPI2) | | | 2048 +-----------+------+--------+---------+---------+---------+ 2049 | Modified | -- | RPI1 | -- | IP6-IP6 | -- | 2050 | headers | | | | (RH3, | | 2051 | | | | | RPI2) | | 2052 +-----------+------+--------+---------+---------+---------+ 2053 | Removed | -- | -- | -- | -- | IP6-IP6 | 2054 | headers | | | | | (RH3, | 2055 | | | | | | RPI2) | 2056 | | | | | | | 2057 +-----------+------+--------+---------+---------+---------+ 2058 | Untouched | -- | -- | RPI1 | RPI1 | RPI | 2059 | headers | | | | |(Ignored)| 2060 +-----------+------+--------+---------+---------+---------+ 2062 Figure 33: Non-SM: Summary of the Use of Headers from RAL to RAL 2063 without encapsulation to the root. 2065 8.3.2. Non-SM: Example of Flow from RAL to RUL 2067 In this case the flow comprises: 2069 RAL --> 6LR_ia --> root (6LBR) --> 6LR_id --> RUL (IPv6 dst node) 2071 For example, a communication flow could be: Node F (RAL) --> Node D 2072 --> Node B --> Node A (root) --> Node B --> Node E --> Node G (RUL) 2074 6LR_ia represents the intermediate routers from source to the root, 1 2075 <= ia <= n, where n is the total number of intermediate routers (6LR) 2077 6LR_id represents the intermediate routers from the root to the 2078 destination, 1 <= id <= m, where m is the total number of the 2079 intermediate routers (6LRs). 2081 As in the previous case, the RAL (6LN) may insert an RPI (RPI1) 2082 header which must be in an IPv6-in-IPv6 header addressed to the root 2083 so that the 6LBR can remove this RPI. The 6LBR will then insert an 2084 RH3 inside a new IPv6-in-IPv6 header addressed to the last 6LR_id 2085 (6LR_id = m) alongside the insertion of RPI2. 2087 If the originating node does not not put the RPI (RPI1) into an IPv6- 2088 in-IPv6 header addressed to the root. Then, the RPI1 is forwarded 2089 down from the root in the inner header to no avail. 2091 The Figure 34 shows the table that summarizes what headers are needed 2092 for this use case when encapsulation to the root takes place. The 2093 Figure 35 shows the table that summarizes what headers are needed for 2094 this use case when no encapsulation to the root takes place. 2096 +-----------+---------+---------+---------+---------+---------+------+ 2097 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL | 2098 | | src | | | | | dst | 2099 | | node | | | | | node | 2100 +-----------+---------+---------+---------+---------+---------+------+ 2101 | Added | IP6-IP6 | | IP6-IP6 | -- | -- | -- | 2102 | headers | (RPI1) | -- | (RH3, | | | | 2103 | | | | RPI2) | | | | 2104 +-----------+---------+---------+---------+---------+---------+------+ 2105 | Modified | -- | | -- | IP6-IP6 | | -- | 2106 | headers | | RPI1 | | (RH3, | -- | | 2107 | | | | | RPI2) | | | 2108 +-----------+---------+---------+---------+---------+---------+------+ 2109 | Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- | 2110 | headers | | | (RPI1) | | (RH3, | | 2111 | | | | | | RPI2) | | 2112 +-----------+---------+---------+---------+---------+---------+------+ 2113 | Untouched | -- | -- | -- | -- | -- | -- | 2114 | headers | | | | | | | 2115 +-----------+---------+---------+---------+---------+---------+------+ 2117 Figure 34: Non-SM: Summary of the use of headers from RAL to RUL with 2118 encapsulation to the root. 2120 +-----------+------+--------+---------+---------+---------+---------+ 2121 | Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_n | RUL | 2122 | | src | | | | | dst | 2123 | | node | | | | | node | 2124 +-----------+------+--------+---------+---------+---------+---------+ 2125 | Inserted | RPI1 | -- | IP6-IP6 | -- | -- | -- | 2126 | headers | | | (RH3, | | | | 2127 | | | | RPI2) | | | | 2128 +-----------+------+--------+---------+---------+---------+---------+ 2129 | Modified | -- | RPI1 | -- | IP6-IP6 | -- | -- | 2130 | headers | | | | (RH3, | | | 2131 | | | | | RPI2) | | | 2132 +-----------+------+--------+---------+---------+---------+---------+ 2133 | Removed | -- | -- | -- | -- | IP6-IP6 | -- | 2134 | headers | | | | | (RH3, | | 2135 | | | | | | RPI2) | | 2136 +-----------+------+--------+---------+---------+---------+---------+ 2137 | Untouched | -- | -- | RPI1 | RPI1 | RPI1 | RPI1 | 2138 | headers | | | | | |(Ignored)| 2139 +-----------+------+--------+---------+---------+---------+---------+ 2141 Figure 35: Non-SM: Summary of the use of headers from RAL to RUL 2142 without encapsulation to the root. 2144 8.3.3. Non-SM: Example of Flow from RUL to RAL 2146 In this case the flow comprises: 2148 RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id 2149 --> RAL dst (6LN) 2151 For example, a communication flow could be: Node G (RUL)--> Node E 2152 --> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL) 2154 6LR_ia represents the intermediate routers from source to the root, 1 2155 <= ia <= n, where n is the total number of intermediate routers (6LR) 2157 6LR_id represents the intermediate routers from the root to the 2158 destination, 1 <= id <= m, where m is the total number of the 2159 intermediate routers (6LR). 2161 In this scenario the RPI (RPI1) is added by the first 6LR (6LR_1) 2162 inside an IPv6-in-IPv6 header addressed to the root. The 6LBR will 2163 remove this RPI, and add it's own IPv6-in-IPv6 header containing an 2164 RH3 header and an RPI (RPI2). 2166 The Figure 36 shows the table that summarizes what headers are needed 2167 for this use case. 2169 +----------+------+---------+---------+---------+---------+---------+ 2170 | Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL | 2171 | | src | | | | | dst | 2172 | | node | | | | | node | 2173 +----------+------+---------+---------+---------+---------+---------+ 2174 | Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- | 2175 | headers | | (RPI1) | | (RH3, | | | 2176 | | | | | RPI2) | | | 2177 +----------+------+---------+---------+---------+---------+---------+ 2178 | Modified | -- | | | -- | IP6-IP6 | -- | 2179 | headers | | -- | RPI1 | | (RH3, | | 2180 | | | | | | RPI2) | | 2181 +----------+------+---------+---------+---------+---------+---------+ 2182 | Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 | 2183 | headers | | -- | | (RPI1) | | (RH3, | 2184 | | | | | | | RPI2) | 2185 +----------+------+---------+---------+---------+---------+---------+ 2186 |Untouched | -- | -- | -- | -- | -- | -- | 2187 | headers | | | | | | | 2188 +----------+------+---------+---------+---------+---------+---------+ 2190 Figure 36: Non-SM: Summary of the use of headers from RUL to RAL. 2192 8.3.4. Non-SM: Example of Flow from RUL to RUL 2194 In this case the flow comprises: 2196 RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id 2197 --> RUL (IPv6 dst node) 2199 For example, a communication flow could be: Node G --> Node E --> 2200 Node B --> Node A (root) --> Node C --> Node J 2202 6LR_ia represents the intermediate routers from source to the root, 1 2203 <= ia <= n, where n is the total number of intermediate routers (6LR) 2205 6LR_id represents the intermediate routers from the root to the 2206 destination, 1 <= id <= m, where m is the total number of the 2207 intermediate routers (6LR). 2209 This scenario is the combination of the previous two cases. 2211 The Figure 37 shows the table that summarizes what headers are needed 2212 for this use case. 2214 +---------+------+-------+-------+---------+-------+---------+------+ 2215 | Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | RUL | 2216 | | src | | | | | | dst | 2217 | | node | | | | | | node | 2218 +---------+------+-------+-------+---------+-------+---------+------+ 2219 | Added | -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- | 2220 | headers | | (RPI1)| | (RH3, | | | | 2221 | | | | | RPI2) | | | | 2222 +---------+------+-------+-------+---------+-------+---------+------+ 2223 | Modified| -- | -- | | -- |IP6-IP6| -- | -- | 2224 | headers | | | RPI1 | | (RH3, | | | 2225 | | | | | | RPI2)| | | 2226 +---------+------+-------+-------+---------+-------+---------+------+ 2227 | Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- | 2228 | headers | | | | (RPI1) | | (RH3, | | 2229 | | | | | | | RPI2) | | 2230 +---------+------+-------+-------+---------+-------+---------+------+ 2231 |Untouched| -- | -- | -- | -- | -- | -- | -- | 2232 | headers | | | | | | | | 2233 +---------+------+-------+-------+---------+-------+---------+------+ 2235 Figure 37: Non-SM: Summary of the use of headers from RUL to RUL 2237 9. Operational Considerations of supporting RUL-leaves 2239 Roughly half of the situations described in this document involve 2240 leaf ("host") nodes that do not speak RPL. These nodes fall into two 2241 further categories: ones that drop a packet that have RPI or RH3 2242 headers, and ones that continue to process a packet that has RPI and/ 2243 or RH3 headers. 2245 [RFC8200] provides for new rules that suggest that nodes that have 2246 not been configured (explicitly) to examine Hop-by-Hop headers, 2247 should ignore those headers, and continue processing the packet. 2248 Despite this, and despite the switch from 0x63 to 0x23, there may be 2249 hosts that are pre-RFC8200, or simply intolerant. Those hosts will 2250 drop packets that continue to have RPL artifacts in them. In 2251 general, such hosts can not be easily supported in RPL LLNs. 2253 There are some specific cases where it is possible to remove the RPL 2254 artifacts prior to forwarding the packet to the leaf host. The 2255 critical thing is that the artifacts have been inserted by the RPL 2256 root inside an IPv6-in-IPv6 header, and that the header has been 2257 addressed to the 6LR immediately prior to the leaf node. In that 2258 case, in the process of removing the IPv6-in-IPv6 header, the 2259 artifacts can also be removed. 2261 The above case occurs whenever traffic originates from the outside 2262 the LLN (the "Internet" cases above), and non-storing mode is used. 2263 In non-storing mode, the RPL root knows the exact topology (as it 2264 must create the RH3 header) and therefore knows which 6LR is prior to 2265 the leaf. For example, in Figure 6, Node E is the 6LR prior to leaf 2266 Node G, or Node C is the 6LR prior to leaf Node J. 2268 traffic originating from the RPL root (such as when the data 2269 collection system is co-located on the RPL root), does not require an 2270 IPv6-in-IPv6 header (in either mode), as the packet is originating at 2271 the root, and the root can insert the RPI and RH3 headers directly 2272 into the packet, as it is formed. Such a packet is slightly smaller, 2273 but only can be sent to nodes (whether RPL aware or not), that will 2274 tolerate the RPL artifacts. 2276 An operator that finds itself with a lot of traffic from the RPL root 2277 to RPL-not-aware-leaves, will have to do IPv6-in-IPv6 encapsulation 2278 if the leaf is not tolerant of the RPL artifacts. Such an operator 2279 could otherwise omit this unnecessary header if it was certain of the 2280 properties of the leaf. 2282 As storing mode can not know the final path of the traffic, 2283 intolerant (that drop packets with RPL artifacts) leaf nodes can not 2284 be supported. 2286 10. Operational considerations of introducing 0x23 2288 This section describes the operational considerations of introducing 2289 the new RPI Option Type of 0x23. 2291 During bootstrapping the node gets the DIO with the information of 2292 RPI Option Type, indicating the new RPI in the DODAG Configuration 2293 option Flag. The DODAG root is in charge to configure the current 2294 network to the new value, through DIO messages and when all the nodes 2295 are set with the new value. The DODAG should change to a new DODAG 2296 version. In case of rebooting, the node does not remember the RPI 2297 Option Type. Thus, the DIO is sent with a flag indicating the new 2298 RPI Option Type. 2300 The DODAG Configuration option is contained in a RPL DIO message, 2301 which contains a unique DTSN counter. The leaf nodes respond to this 2302 message with DAO messages containing the same DTSN. This is a normal 2303 part of RPL routing; the RPL root therefore knows when the updated 2304 DODAG Configuration option has been seen by all nodes. 2306 Before the migration happens, all the RPL-aware nodes should support 2307 both values . The migration procedure it is triggered when the DIO 2308 is sent with the flag indicating the new RPI Option Type. Namely, it 2309 remains at 0x63 until it is sure that the network is capable of 0x23, 2310 then it abruptly change to 0x23. This options allows to send packets 2311 to not-RPL nodes, which should ignore the option and continue 2312 processing the packets. 2314 In case that a node join to a network that only process 0x63, it 2315 would produce a flag day as was mentioned previously. Indicating the 2316 new RPI in the DODAG Configuration option Flag is a way to avoid the 2317 flag day in a network. It is recommended that a network process both 2318 options to enable interoperability. 2320 11. IANA Considerations 2322 This document updates the registration made in [RFC6553] Destination 2323 Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in 2324 Figure 38. 2326 +-------+-------------------+------------------------+---------- -+ 2327 | Hex | Binary Value | Description | Reference | 2328 + Value +-------------------+ + + 2329 | | act | chg | rest | | | 2330 +-------+-----+-----+-------+------------------------+------------+ 2331 | 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)| 2332 +-------+-----+-----+-------+------------------------+------------+ 2333 | 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] | 2334 | | | | | |[RFCXXXX](*)| 2335 +-------+-----+-----+-------+------------------------+------------+ 2337 Figure 38: Option Type in RPL Option.(*)represents this document 2339 DODAG Configuration option is updated as follows (Figure 39): 2341 +------------+-----------------+---------------+ 2342 | Bit number | Description | Reference | 2343 +------------+-----------------+---------------+ 2344 | 3 | RPI 0x23 enable | This document | 2345 +------------+-----------------+---------------+ 2347 Figure 39: DODAG Configuration option Flag to indicate the RPI-flag- 2348 day. 2350 12. Security Considerations 2352 The security considerations covered in [RFC6553] and [RFC6554] apply 2353 when the packets are in the RPL Domain. 2355 The IPv6-in-IPv6 mechanism described in this document is much more 2356 limited than the general mechanism described in [RFC2473]. The 2357 willingness of each node in the LLN to decapsulate packets and 2358 forward them could be exploited by nodes to disguise the origin of an 2359 attack. 2361 While a typical LLN may be a very poor origin for attack traffic (as 2362 the networks tend to be very slow, and the nodes often have very low 2363 duty cycles), given enough nodes, LLNs could still have a significant 2364 impact, particularly if attack is targeting another LLN. 2365 Additionally, some uses of RPL involve large backbone ISP scale 2366 equipment [I-D.ietf-anima-autonomic-control-plane], which may be 2367 equipped with multiple 100Gb/s interfaces. 2369 Blocking or careful filtering of IPv6-in-IPv6 traffic entering the 2370 LLN as described above will make sure that any attack that is mounted 2371 must originate from compromised nodes within the LLN. The use of 2372 BCP38 [BCP38] filtering at the RPL root on egress traffic will both 2373 alert the operator to the existence of the attack, as well as drop 2374 the attack traffic. As the RPL network is typically numbered from a 2375 single prefix, which is itself assigned by RPL, BCP38 filtering 2376 involves a single prefix comparison and should be trivial to 2377 automatically configure. 2379 There are some scenarios where IPv6-in-IPv6 traffic should be allowed 2380 to pass through the RPL root, such as the IPv6-in-IPv6 mediated 2381 communications between a new Pledge and the Join Registrar/ 2382 Coordinator (JRC) when using [I-D.ietf-anima-bootstrapping-keyinfra] 2383 and [I-D.ietf-6tisch-dtsecurity-zerotouch-join]. This is the case 2384 for the RPL root to do careful filtering: it occurs only when the 2385 Join Coordinator is not co-located inside the RPL root. 2387 With the above precautions, an attack using IPv6-in-IPv6 tunnels can 2388 only be by a node within the LLN on another node within the LLN. 2389 Such an attack could, of course, be done directly. An attack of this 2390 kind is meaningful only if the source addresses are either fake or if 2391 the point is to amplify return traffic. Such an attack, could also 2392 be done without the use of IPv6-in-IPv6 headers using forged source 2393 addresses. If the attack requires bi-directional communication, then 2394 IPv6-in-IPv6 provides no advantages. 2396 Whenever IPv6-in-IPv6 headers are being proposed, there is a concern 2397 about creating security issues. In the Security Considerations 2398 section of [RFC2473], it was suggested that tunnel entry and exit 2399 points can be secured by securing the IPv6 path between them. This 2400 recommendation is not practical for RPL networks. [RFC5406] goes 2401 into some detail on what additional details would be needed in order 2402 to "Use IPsec". Use of ESP would prevent [RFC8138] compression 2403 (compression must occur before encryption), and [RFC8138] compression 2404 is lossy in a way that prevents use of AH. These are minor issues. 2405 The major issue is how to establish trust enough such that IKEv2 2406 could be used. This would require a system of certificates to be 2407 present in every single node, including any Internet nodes that might 2408 need to communicate with the LLN. Thus, using IPsec requires a 2409 global PKI in the general case. 2411 More significantly, the use of IPsec tunnels to protect the IPv6-in- 2412 IPv6 headers would in the general case scale with the square of the 2413 number of nodes. This is a lot of resource for a constrained nodes 2414 on a constrained network. In the end, the IPsec tunnels would be 2415 providing only BCP38-like origin authentication! That is, IPsec 2416 provides a transitive guarantee to the tunnel exit point that the 2417 tunnel entry point did BCP38 on traffic going in. Just doing origin 2418 filtering per BCP 38 at the entry and exit of the LLN provides a 2419 similar level of security without all the scaling and trust problems 2420 related to IPv6 tunnels as discussed in RFC 2473. IPsec is not 2421 recommended. 2423 An LLN with hostile nodes within it would not be protected against 2424 impersonation with the LLN by entry/exit filtering. 2426 The RH3 header usage described here can be abused in equivalent ways 2427 (to disguise the origin of traffic and attack other nodes) with an 2428 IPv6-in-IPv6 header to add the needed RH3 header. As such, the 2429 attacker's RH3 header will not be seen by the network until it 2430 reaches the end host, which will decapsulate it. An end-host should 2431 be suspicious about an RH3 header which has additional hops which 2432 have not yet been processed, and SHOULD ignore such a second RH3 2433 header. 2435 In addition, the LLN will likely use [RFC8138] to compress the IPv6- 2436 in-IPv6 and RH3 headers. As such, the compressor at the RPL-root 2437 will see the second RH3 header and MAY choose to discard the packet 2438 if the RH3 header has not been completely consumed. A consumed 2439 (inert) RH3 header could be present in a packet that flows from one 2440 LLN, crosses the Internet, and enters another LLN. As per the 2441 discussion in this document, such headers do not need to be removed. 2442 However, there is no case described in this document where an RH3 is 2443 inserted in a non-storing network on traffic that is leaving the LLN, 2444 but this document should not preclude such a future innovation. It 2445 should just be noted that an incoming RH3 must be fully consumed, or 2446 very carefully inspected. 2448 The RPI, if permitted to enter the LLN, could be used by an attacker 2449 to change the priority of a packet by selecting a different 2450 RPLInstanceID, perhaps one with a higher energy cost, for instance. 2451 It could also be that not all nodes are reachable in an LLN using the 2452 default RPLInstanceID, but a change of RPLInstanceID would permit an 2453 attacker to bypass such filtering. Like the RH3, an RPI is to be 2454 inserted by the RPL root on traffic entering the LLN by first 2455 inserting an IPv6-in-IPv6 header. The attacker's RPI therefore will 2456 not be seen by the network. Upon reaching the destination node the 2457 RPI has no further meaning and is just skipped; the presence of a 2458 second RPI will have no meaning to the end node as the packet has 2459 already been identified as being at it's final destination. 2461 The RH3 and RPIs could be abused by an attacker inside of the network 2462 to route packets on non-obvious ways, perhaps eluding observation. 2463 This usage appears consistent with a normal operation of [RFC6997] 2464 and can not be restricted at all. This is a feature, not a bug. 2466 [RFC7416] deals with many other threats to LLNs not directly related 2467 to the use of IPv6-in-IPv6 headers, and this document does not change 2468 that analysis. 2470 Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an 2471 attack on another part of the LLN, while disguising the origin of the 2472 attack. The mechanism can even be abused to make it appear that the 2473 attack is coming from outside the LLN, and unless countered, this 2474 could be used to mount a Distributed Denial Of Service attack upon 2475 nodes elsewhere in the Internet. See [DDOS-KREBS] for an example of 2476 such attacks already seen in the real world. 2478 If an attack comes from inside of LLN, it can be alleviated with SAVI 2479 (Source Address Validation Improvement) using [RFC8505] with 2480 [I-D.ietf-6lo-ap-nd]. The attacker will not be able to source 2481 traffic with an address that is not registered, and the registration 2482 process checks for topological correctness. Notice that there is an 2483 L2 authentication in most of the cases. If an attack comes from 2484 outside LLN IPv6-in- IPv6 can be used to hide inner routing headers, 2485 but by construction, the RH3 can typically only address nodes within 2486 the LLN. That is, an RH3 with a CmprI less than 8 , should be 2487 considered an attack (see RFC6554, section 3). 2489 Nodes outside of the LLN will need to pass IPv6-in-IPv6 traffic 2490 through the RPL root to perform this attack. To counter, the RPL 2491 root SHOULD either restrict ingress of IPv6-in-IPv6 packets (the 2492 simpler solution), or it SHOULD walk the IP header extension chain 2493 until it can inspect the upper-layer-payload as described in 2494 [RFC7045]. In particular, the RPL root SHOULD do [BCP38] processing 2495 on the source addresses of all IP headers that it examines in both 2496 directions. 2498 Note: there are some situations where a prefix will spread across 2499 multiple LLNs via mechanisms such as the one described in 2500 [I-D.ietf-6lo-backbone-router]. In this case the BCP38 filtering 2501 needs to take this into account, either by exchanging detailed 2502 routing information on each LLN, or by moving the BCP38 filtering 2503 further towards the Internet, so that the details of the multiple 2504 LLNs do not matter. 2506 13. Acknowledgments 2508 This work is done thanks to the grant given by the StandICT.eu 2509 project. 2511 A special BIG thanks to C. M. Heard for the help with the 2512 Section 4. Much of the redaction in that section is based on his 2513 comments. 2515 Additionally, the authors would like to acknowledge the review, 2516 feedback, and comments of (alphabetical order): Dominique Barthel, 2517 Robert Cragie, Simon Duquennoy, Ralph Droms, Cenk Guendogan, Rahul 2518 Jadhav, Benjamin Kaduk, Matthias Kovatsch, Gustavo Mercado, 2519 Subramanian Moonesamy, Marcela Orbiscay, Charlie Perkins, Cristian 2520 Perez, Alvaro Retana, Peter van der Stok, Xavier Vilajosana, Eric 2521 Vyncke and Thomas Watteyne. 2523 14. References 2525 14.1. Normative References 2527 [BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering: 2528 Defeating Denial of Service Attacks which employ IP Source 2529 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 2530 May 2000, . 2532 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2533 Requirement Levels", BCP 14, RFC 2119, 2534 DOI 10.17487/RFC2119, March 1997, 2535 . 2537 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 2538 Notification", RFC 6040, DOI 10.17487/RFC6040, November 2539 2010, . 2541 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 2542 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 2543 DOI 10.17487/RFC6282, September 2011, 2544 . 2546 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 2547 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 2548 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 2549 Low-Power and Lossy Networks", RFC 6550, 2550 DOI 10.17487/RFC6550, March 2012, 2551 . 2553 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 2554 Power and Lossy Networks (RPL) Option for Carrying RPL 2555 Information in Data-Plane Datagrams", RFC 6553, 2556 DOI 10.17487/RFC6553, March 2012, 2557 . 2559 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 2560 Routing Header for Source Routes with the Routing Protocol 2561 for Low-Power and Lossy Networks (RPL)", RFC 6554, 2562 DOI 10.17487/RFC6554, March 2012, 2563 . 2565 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 2566 of IPv6 Extension Headers", RFC 7045, 2567 DOI 10.17487/RFC7045, December 2013, 2568 . 2570 [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power 2571 Wireless Personal Area Network (6LoWPAN) Paging Dispatch", 2572 RFC 8025, DOI 10.17487/RFC8025, November 2016, 2573 . 2575 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 2576 "IPv6 over Low-Power Wireless Personal Area Network 2577 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 2578 April 2017, . 2580 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2581 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2582 May 2017, . 2584 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2585 (IPv6) Specification", STD 86, RFC 8200, 2586 DOI 10.17487/RFC8200, July 2017, 2587 . 2589 [RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node 2590 Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504, 2591 January 2019, . 2593 14.2. Informative References 2595 [DDOS-KREBS] 2596 Goodin, D., "Record-breaking DDoS reportedly delivered by 2597 >145k hacked cameras", September 2016, 2598 . 2601 [I-D.ietf-6lo-ap-nd] 2602 Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, 2603 "Address Protected Neighbor Discovery for Low-power and 2604 Lossy Networks", draft-ietf-6lo-ap-nd-20 (work in 2605 progress), March 2020. 2607 [I-D.ietf-6lo-backbone-router] 2608 Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 2609 Backbone Router", draft-ietf-6lo-backbone-router-19 (work 2610 in progress), March 2020. 2612 [I-D.ietf-6tisch-dtsecurity-zerotouch-join] 2613 Richardson, M., "6tisch Zero-Touch Secure Join protocol", 2614 draft-ietf-6tisch-dtsecurity-zerotouch-join-04 (work in 2615 progress), July 2019. 2617 [I-D.ietf-anima-autonomic-control-plane] 2618 Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic 2619 Control Plane (ACP)", draft-ietf-anima-autonomic-control- 2620 plane-24 (work in progress), March 2020. 2622 [I-D.ietf-anima-bootstrapping-keyinfra] 2623 Pritikin, M., Richardson, M., Eckert, T., Behringer, M., 2624 and K. Watsen, "Bootstrapping Remote Secure Key 2625 Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- 2626 keyinfra-38 (work in progress), March 2020. 2628 [I-D.ietf-intarea-tunnels] 2629 Touch, J. and M. Townsley, "IP Tunnels in the Internet 2630 Architecture", draft-ietf-intarea-tunnels-10 (work in 2631 progress), September 2019. 2633 [I-D.ietf-roll-unaware-leaves] 2634 Thubert, P. and M. Richardson, "Routing for RPL Leaves", 2635 draft-ietf-roll-unaware-leaves-13 (work in progress), 2636 March 2020. 2638 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2639 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 2640 December 1998, . 2642 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 2643 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 2644 December 1998, . 2646 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 2647 Control Message Protocol (ICMPv6) for the Internet 2648 Protocol Version 6 (IPv6) Specification", STD 89, 2649 RFC 4443, DOI 10.17487/RFC4443, March 2006, 2650 . 2652 [RFC5406] Bellovin, S., "Guidelines for Specifying the Use of IPsec 2653 Version 2", BCP 146, RFC 5406, DOI 10.17487/RFC5406, 2654 February 2009, . 2656 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 2657 "IPv6 Flow Label Specification", RFC 6437, 2658 DOI 10.17487/RFC6437, November 2011, 2659 . 2661 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 2662 Bormann, "Neighbor Discovery Optimization for IPv6 over 2663 Low-Power Wireless Personal Area Networks (6LoWPANs)", 2664 RFC 6775, DOI 10.17487/RFC6775, November 2012, 2665 . 2667 [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and 2668 J. Martocci, "Reactive Discovery of Point-to-Point Routes 2669 in Low-Power and Lossy Networks", RFC 6997, 2670 DOI 10.17487/RFC6997, August 2013, 2671 . 2673 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 2674 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 2675 2014, . 2677 [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., 2678 and M. Richardson, Ed., "A Security Threat Analysis for 2679 the Routing Protocol for Low-Power and Lossy Networks 2680 (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, 2681 . 2683 [RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal 2684 IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH) 2685 Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180, 2686 May 2017, . 2688 [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. 2689 Perkins, "Registration Extensions for IPv6 over Low-Power 2690 Wireless Personal Area Network (6LoWPAN) Neighbor 2691 Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, 2692 . 2694 Authors' Addresses 2696 Maria Ines Robles 2697 Universidad Tecno. Nac.(UTN)-FRM, Argentina / Aalto University, Finland 2699 Email: mariainesrobles@gmail.com 2700 Michael C. Richardson 2701 Sandelman Software Works 2702 470 Dawson Avenue 2703 Ottawa, ON K1Z 5V7 2704 CA 2706 Email: mcr+ietf@sandelman.ca 2707 URI: http://www.sandelman.ca/mcr/ 2709 Pascal Thubert 2710 Cisco Systems, Inc 2711 Building D 2712 45 Allee des Ormes - BP1200 2713 MOUGINS - Sophia Antipolis 06254 2714 FRANCE 2716 Phone: +33 497 23 26 34 2717 Email: pthubert@cisco.com