idnits 2.17.00 (12 Aug 2021) /tmp/idnits31807/draft-ietf-roll-useofrplinfo-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 20, 2016) is 2131 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: draft-ietf-6man-rfc2460bis has been published as RFC 8200 ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: draft-ietf-6tisch-architecture has been published as RFC 9030 == Outdated reference: draft-ietf-roll-routing-dispatch has been published as RFC 8138 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ROLL Working Group M. Robles 3 Internet-Draft Ericsson 4 Intended status: Informational M. Richardson 5 Expires: January 21, 2017 SSW 6 P. Thubert 7 Cisco 8 July 20, 2016 10 When to use RFC 6553, 6554 and IPv6-in-IPv6 11 draft-ietf-roll-useofrplinfo-07 13 Abstract 15 This document looks at different data flows through LLN (Low-Power 16 and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power 17 and Lossy Networks) is used to establish routing. The document 18 enumerates the cases where RFC 6553, RFC 6554 and IPv6-in-IPv6 19 encapsulation is required. This analysis provides the basis on which 20 to design efficient compression of these headers. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on January 21, 2017. 39 Copyright Notice 41 Copyright (c) 2016 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology and Requirements Language . . . . . . . . . . . . 3 58 2.1. hop-by-hop IPv6-in-IPv6 headers . . . . . . . . . . . . . 4 59 3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4 60 4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 7 61 5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 8 62 5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 9 63 5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 10 64 5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 11 65 5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 11 66 5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 12 67 5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 12 68 5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 13 69 5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 14 70 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 14 71 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 15 72 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 15 73 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 74 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 16 75 6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 16 76 6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 17 77 6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 17 78 6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 18 79 6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 19 80 6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 19 81 6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 20 82 6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 21 83 6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 21 84 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 22 85 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 23 86 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 24 87 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 88 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 24 89 7. Observations about the problem . . . . . . . . . . . . . . . 25 90 7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 25 91 7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 26 92 8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 26 93 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 94 10. Security Considerations . . . . . . . . . . . . . . . . . . . 27 95 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 96 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 97 12.1. Normative References . . . . . . . . . . . . . . . . . . 27 98 12.2. Informative References . . . . . . . . . . . . . . . . . 28 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 101 1. Introduction 103 RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) 104 [RFC6550] is a routing protocol for constrained networks. RFC 6553 105 [RFC6553] defines the "RPL option" (RPI), carried within the IPv6 106 Hop-by-Hop header to quickly identify inconsistencies (loops) in the 107 routing topology. RFC 6554 [RFC6554] defines the "RPL Source Route 108 Header" (RH3), an IPv6 Extension Header to deliver datagrams within a 109 RPL routing domain, particularly in non-storing mode. 111 These various items are referred to as RPL artifacts, and they are 112 seen on all of the data-plane traffic that occurs in RPL routed 113 networks; they do not in general appear on the RPL control plane 114 traffic at all which is mostly hop-by-hop traffic (one exception 115 being DAO messages in non-storing mode). 117 It has become clear from attempts to do multi-vendor 118 interoperability, and from a desire to compress as many of the above 119 artifacts as possible that not all implementors agree when artifacts 120 are necessary, or when they can be safely omitted, or removed. 122 An interim meeting went through the 24 cases defined here to discover 123 if there were any shortcuts, and this document is the result of that 124 discussion. This document should not be defining anything new, but 125 it may clarify what is correct and incorrect behaviour. 127 The related document A Routing Header Dispatch for 6LoWPAN (6LoRH) 128 [I-D.ietf-roll-routing-dispatch] defines a method to compress RPL 129 Option information and Routing Header type 3 [RFC6554], an efficient 130 IP-in-IP technique, and use cases proposed for the 131 [Second6TischPlugtest] involving 6loRH. 133 2. Terminology and Requirements Language 135 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 136 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 137 document are to be interpreted as described in RFC 2119 [RFC2119]. 139 Terminology defined in [RFC7102] applies to this document: LBR, LLN, 140 RPL, RPL Domain and ROLL. 142 2.1. hop-by-hop IPv6-in-IPv6 headers 144 The term "hop-by-hop IPv6-in-IPv6" header refers to: adding a header 145 that originates from a node to an adjacent node, using the addresses 146 (usually the GUA or ULA, but could use the link-local addresses) of 147 each node. If the packet must traverse multiple hops, then it must 148 be decapsulated at each hop, and then re-encapsulated again in a 149 similar fashion. 151 3. Sample/reference topology 153 A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone 154 Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf 155 logically organized in a DODAG structure (Destination Oriented 156 Directed Acyclic Graph). 158 RPL defines the RPL Control messages (control plane), a new ICMPv6 159 [RFC4443] message with Type 155. DIS (DODAG Information 160 Solicitation), DIO (DODAG Information Object) and DAO (Destination 161 Advertisement Object) messages are all RPL Control messages but with 162 different Code values. A RPL Stack is showed in Figure 1. 164 RPL supports two modes of Downward traffic: in storing mode (RPL-SM), 165 it is fully stateful or an in non-storing (RPL-NSM), it is fully 166 source routed. A RPL Instance is either fully storing or fully non- 167 storing, i.e. a RPL Instance with a combination of storing and non- 168 storing nodes is not supported with the current specifications at the 169 time of writing this document. 171 +--------------+ 172 | Upper Layers | 173 | | 174 +--------------+ 175 | RPL | 176 | | 177 +--------------+ 178 | ICMPv6 | 179 | | 180 +--------------+ 181 | IPv6 | 182 | | 183 +--------------+ 184 | 6LoWPAN | 185 | | 186 +--------------+ 187 | PHY-MAC | 188 | | 189 +--------------+ 191 Figure 1: RPL Stack. 193 +---------+ 194 +---+Internet | 195 | +---------+ 196 | 197 +----+--+ 198 | DODAG | node:01 199 +---------+ Root +----------+ 200 | | 6LBR | | 201 | +----+--+ | 202 | | | 203 | | | 204 ... ... ... 205 | | | 206 +-----+-+ +--+---+ +--+---+ 207 |6LR | | | | | 208 +-----+ | | | | | 209 | | 11 | | 12 | | 13 +------+ 210 | +-----+-+ +-+----+ +-+----+ | 211 | | | | | 212 | | | | | 213 | 21 | 22 | 23 | 24 | 25 214 +-+---+ +-+---+ +--+--+ +- --+ +---+-+ 215 |Leaf | | | | | |Leaf| |Leaf | 216 | 6LN | | | | | | 6LN| | 6LN | 217 +-----+ +-----+ +-----+ +----+ +-----+ 219 Figure 2: A reference RPL Topology. 221 In Figure 2 is showed the reference RPL Topology for this document. 222 The numbers in or above the nodes are there so that they may be 223 referenced in subsequent sections. In the figure, a 6LN can be a 224 router or a host. The 6LN leafs marked as (21) and (25) are routers. 225 The leaf marked 6LN (24) is a device which does not speak RPL at all 226 (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/DAC and 227 efficient-ND only to participate in the network [RFC6775]. In the 228 document this leaf (24) is often named IPv6 node. The 6LBR in the 229 figure is the root of the Global DODAG. 231 This document is in part motivated by the work that is ongoing at the 232 6TiSCH working group. The 6TiSCH architecture 233 [I-D.ietf-6tisch-architecture] draft explains the network 234 architecture of a 6TiSCH network. 236 4. Use cases 238 In data plane context a combination of RFC6553, RFC6554 and IPv6-in- 239 IPv6 encapsulation is going to be analyzed for the following traffic 240 flows. 242 This version of the document assumes the changes in 243 [I-D.ietf-6man-rfc2460bis] are passed. 245 RPL-aware-leaf to root 247 root to RPL-aware-leaf 249 not-RPL-aware-leaf to root 251 root to not-RPL-aware-leaf 253 RPL-aware-leaf to Internet 255 Internet to RPL-aware-leaf 257 not-RPL-aware-leaf to Internet 259 Internet to not-RPL-aware-leaf 261 RPL-aware-leaf to RPL-aware-leaf (storing and non-storing) 263 RPL-aware-leaf to not-RPL-aware-leaf (non-storing) 265 not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing) 267 not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing) 269 This document assumes the rule that a Header cannot be inserted or 270 removed on the fly inside an IPv6 packet that is being routed. This 271 is a fundamental precept of the IPv6 architecture as outlined in 272 [RFC2460] is that Extensions may not be added or removed except by 273 the sender or the receiver. (A revision to RFC2460 considered 274 changing this rule, but has kept it) 276 But, options in the Hop-by-Hop option which are marked with option 277 type 01 ([RFC2460] section 4.2 and [I-D.ietf-6man-rfc2460bis]) SHOULD 278 be ignored when received by a host or router which does not 279 understand that option. 281 This means that in general, any packet that leaves the RPL domain of 282 an LLN (or leaves the LLN entirely) will NOT be discarded, even if it 283 has the [RFC6553] RPL Option Header known as the RPI or [RFC6554] 284 SRH3 Extension Header (S)RH3. 286 With abolition of one of these rules it means that the RPI Hop-by-Hop 287 option MAY be left in place even if the end host does host understand 288 it. This collapses many of the cases above (where it says "or") 290 An intermediate router that needs to add an extension header (SHR3 or 291 RPI Option) must encapsulate the packet in an (additional) outer IP 292 header where the new header can be placed. 294 This also means that a Header can only be removed by an intermediate 295 router if it is placed in an encapsulating IPv6 Header, and in that 296 case, the whole encapsulating header must be removed - a replacement 297 may be added. Further, an intermediate router can only remove such 298 an outer header if that outer header has the router as the 299 destination! 301 Both RPI and RH3 headers may be modified by routers on the path of 302 the packet without the need to add to remove an encapsulating header. 303 Both headers were designed with this modification in mind, and both 304 the RPL RH and the RPL option are marked mutable but recoverable, so 305 an IPsec AH security header can be applied across these headers, but 306 it may not secure all the values in those headers. 308 RPI should be present in every single RPL data packet. There is one 309 exception in non-storing mode: when a packet is going down from the 310 root. In a downward non-storing mode, the entire route is written, 311 so there can be no loops by construction, nor any confusion about 312 which forwarding table to use. There may be cases (such as in 313 6tisch) where the instanceID may still be needed to pick an 314 appropriate priority or channel at each hop. 316 In the tables present in this document, the term "RPL aware leaf" is 317 has been shortened to "Raf", and "not-RPL aware leaf" has been 318 shortened to "~Raf" to make the table fit in available space. 320 The earlier examples are more extensive to make sure that the process 321 is clear, while later examples are more consise. 323 5. Storing mode 325 In storing mode (fully stateful), the sender cannot determine whether 326 the destination is RPL-capable and thus would need an IP-in-IP 327 header. The IP-in-IP header needs to be addressed on a hop-by-hop 328 basis so that the last 6LR can remove the RPI header. Additionally, 329 The sender can determine if the destination is inside the LLN by 330 looking if the destination address is matched by the DIO's PIO 331 option. 333 The following table summarizes what headers are needed in the 334 following scenarios, and indicates when the IP-in-IP header must be 335 inserted on a hop-by-hop basis, and when it can target the 336 destination node directly. There are three possible situations: hop- 337 by-hop necessary (indicated by "hop"), or destination address 338 possible (indicated by "dst"). In all cases hop by hop can be used. 339 In cases where no IP-in-IP header is needed, the column is left 340 blank. 342 The leaf can be a router 6LR or a host, both indicated as 6LN. 344 +--------------+-------+-------+-----------+---------------+ 345 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 346 +--------------+-------+-------+-----------+---------------+ 347 | Raf to root | Yes | No | No | -- | 348 | root to Raf | Yes | No | No | -- | 349 | root to ~Raf | Yes | No | Yes | hop | 350 | ~Raf to root | Yes | No | Yes | root | 351 | Raf to Int | Yes | No | Yes | root | 352 | Int to Raf | Yes | No | Yes | raf | 353 | ~Raf to Int | Yes | No | Yes | root | 354 | Int to ~Raf | Yes | No | Yes | hop | 355 | Raf to Raf | Yes | No | No | -- | 356 | Raf to ~Raf | Yes | No | Yes | hop | 357 | ~Raf to Raf | Yes | No | Yes | dst | 358 | ~Raf to ~Raf | Yes | No | Yes | hop | 359 +--------------+-------+-------+-----------+---------------+ 361 Table 1: Headers needed in Storing mode: RPI, RH3, IP-in-IP 362 encapsulation 364 5.1. Example of Flow from RPL-aware-leaf to root 366 In storing mode, RFC 6553 (RPI) is used to send RPL Information 367 instanceID and rank information. 369 As stated in Section 16.2 of [RFC6550] a RPL-aware-leaf node does 370 not generally issue DIO messages; a leaf node accepts DIO messages 371 from upstream. (When the inconsistency in routing occurs, a leaf 372 node will generate a DIO with an infinite rank, to fix it). It may 373 issue DAO and DIS messages though it generally ignores DAO and DIS 374 messages. 376 In storing mode, RFC 6553 (RPI) is used to send RPL Information 377 instanceID and rank information. 379 In this case the flow comprises: 381 RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR) 383 As it was mentioned In this document 6LRs, 6LBR are always full- 384 fledge RPL routers. 386 The 6LN inserts the RPI header, and sends the packet to 6LR which 387 decrements the rank in RPI and sends the packet up. When the packet 388 arrives at 6LBR, the RPI is removed and the packet is processed. 390 No IP-in-IP header is required. 392 The RPI header can be removed by the 6LBR because the packet is 393 addressed to the 6LBR. The 6LN must know that it is communicating 394 with the 6LBR to make use of this scenario. The 6LN can know the 395 address of the 6LBR because it knows the address of the root via the 396 DODAGID in the DIO messages. 398 +-------------------+-----+------+------+ 399 | Header | 6LN | 6LR | 6LBR | 400 +-------------------+-----+------+------+ 401 | Inserted headers | RPI | -- | -- | 402 | Removed headers | -- | -- | RPI | 403 | Re-added headers | -- | -- | -- | 404 | Modified headers | -- | RPI | -- | 405 | Untouched headers | -- | -- | -- | 406 +-------------------+-----+------+------+ 408 Storing: Summary of the use of headers from RPL-aware-leaf to root 410 5.2. Example of Flow from root to RPL-aware-leaf 412 In this case the flow comprises: 414 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 416 In this case the 6LBR inserts RPI header and sends the packet down, 417 the 6LR is going to increment the rank in RPI (examines instanceID 418 for multiple tables), the packet is processed in 6LN and RPI removed. 420 No IP-in-IP header is required. 422 +-------------------+------+-------+------+ 423 | Header | 6LBR | 6LR | 6LN | 424 +-------------------+------+-------+------+ 425 | Inserted headers | RPI | -- | -- | 426 | Removed headers | -- | -- | RPI | 427 | Re-added headers | -- | -- | -- | 428 | Modified headers | -- | RPI | -- | 429 | Untouched headers | -- | -- | -- | 430 +-------------------+------+-------+------+ 432 Storing: Summary of the use of headers from root to RPL-aware-leaf 434 5.3. Example of Flow from root to not-RPL-aware-leaf 436 In this case the flow comprises: 438 root (6LBR)--> 6LR --> not-RPL-aware-leaf (6LN) 440 As the RPI extension can be ignored by the not-RPL-aware leaf, this 441 situation is identical to the previous scenario. 443 +-------------------+------+-----+------+ 444 | Header | 6LBR | 6LR | IPv6 | 445 +-------------------+------+-----+------+ 446 | Inserted headers | -- | -- | -- | 447 | Removed headers | -- | -- | -- | 448 | Re-added headers | -- | -- | -- | 449 | Modified headers | -- | -- | -- | 450 | Untouched headers | -- | -- | -- | 451 +-------------------+------+-----+------+ 453 Storing: Summary of the use of headers from root to not-RPL-aware- 454 leaf 456 5.4. Example of Flow from not-RPL-aware-leaf to root 458 In this case the flow comprises: 460 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 462 When the packet arrives from IPv6 node to 6LR, the 6LR will insert an 463 RPI header, encapsuladed in a IPv6-in-IPv6 header. The IPv6-in-IPv6 464 header can be addressed to the next hop, or to the root. The root 465 removes the header and processes the packet. 467 +-------------------+------+----------------+---------------+ 468 | Header | IPv6 | 6LR | 6LBR | 469 +-------------------+------+----------------+---------------+ 470 | Inserted headers | -- | IP-in-IP(RPI) | -- | 471 | Removed headers | -- | -- | IP-in-IP(RPI) | 472 | Re-added headers | -- | -- | -- | 473 | Modified headers | -- | -- | -- | 474 | Untouched headers | -- | -- | -- | 475 +-------------------+------+----------------+---------------+ 477 Storing: Summary of the use of headers from not-RPL-aware-leaf to 478 root 480 5.5. Example of Flow from RPL-aware-leaf to Internet 482 RPL information from RFC 6553 MAY go out to Internet as it will be 483 ignored by nodes which have not been configured to be RPI aware. 485 In this case the flow comprises: 487 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 489 No IP-in-IP header is required. 491 +-------------------+------+------+------+----------+ 492 | Header | 6LN | 6LR | 6LBR | Internet | 493 +-------------------+------+------+------+----------+ 494 | Inserted headers | RPI | -- | -- | -- | 495 | Removed headers | -- | -- | -- | -- | 496 | Re-added headers | -- | -- | -- | -- | 497 | Modified headers | -- | RPI | -- | -- | 498 | Untouched headers | -- | -- | -- | -- | 499 +-------------------+------+------+------+----------+ 501 Storing: Summary of the use of headers from RPL-aware-leaf to 502 Internet 504 5.6. Example of Flow from Internet to RPL-aware-leaf 506 In this case the flow comprises: 508 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 510 When the packet arrives from Internet to 6LBR the RPI header is added 511 in a outer IPv6-in-IPv6 header and sent to 6LR, which modifies the 512 rank in the RPI. When the packet arrives at 6LN the RPI header is 513 removed and the packet processed. 515 +-----------------+----------+---------------+------+---------------+ 516 | Header | Internet | 6LBR | 6LR | 6LN | 517 +-----------------+----------+---------------+------+---------------+ 518 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 519 | headers | | | | | 520 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 521 | Re-added | -- | -- | -- | -- | 522 | headers | | | | | 523 | Modified | -- | -- | RPI | -- | 524 | headers | | | | | 525 | Untouched | -- | -- | -- | -- | 526 | headers | | | | | 527 +-----------------+----------+---------------+------+---------------+ 529 Storing: Summary of the use of headers from Internet to RPL-aware- 530 leaf 532 5.7. Example of Flow from not-RPL-aware-leaf to Internet 534 In this case the flow comprises: 536 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 538 The 6LR node will add an IP-in-IP(RPI) header addressed either to the 539 root, or hop-by-hop such that the root can remove the RPI header 540 before passing upwards. 542 The originating node will ideally leave the IPv6 flow label as zero 543 so that it can be better compressed through the LLN, and the 6LBR 544 will set the flow label to a non-zero value when sending to the 545 Internet. 547 +-----------------+------+---------------+---------------+----------+ 548 | Header | 6LN | 6LR | 6LBR | Internet | 549 +-----------------+------+---------------+---------------+----------+ 550 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 551 | headers | | | | | 552 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 553 | Re-added | -- | -- | -- | -- | 554 | headers | | | | | 555 | Modified | -- | -- | -- | -- | 556 | headers | | | | | 557 | Untouched | -- | -- | -- | -- | 558 | headers | | | | | 559 +-----------------+------+---------------+---------------+----------+ 561 Storing: Summary of the use of headers from not-RPL-aware-leaf to 562 Internet 564 5.8. Example of Flow from Internet to non-RPL-aware-leaf 566 In this case the flow comprises: 568 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) 570 The 6LBR will have to add an RPI header within an IP-in-IP header. 571 The IP-in-IP can be addressed to the not-RPL-aware-leaf, leaving the 572 RPI inside. 574 The 6LBR MAY set the flow label on the inner IP-in-IP header to zero 575 in order to aid in compression, as the packet will not emerge again 576 from the LLN. 578 +-----------------+----------+---------------+---------------+------+ 579 | Header | Internet | 6LBR | 6LR | IPv6 | 580 +-----------------+----------+---------------+---------------+------+ 581 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 582 | headers | | | | | 583 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 584 | Re-added | -- | -- | -- | -- | 585 | headers | | | | | 586 | Modified | -- | -- | -- | -- | 587 | headers | | | | | 588 | Untouched | -- | -- | -- | -- | 589 | headers | | | | | 590 +-----------------+----------+---------------+---------------+------+ 592 Storing: Summary of the use of headers from Internet to non-RPL- 593 aware-leaf 595 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 597 In [RFC6550] RPL allows a simple one-hop optimization for both 598 storing and non-storing networks. A node may send a packet destined 599 to a one-hop neighbor directly to that node. Section 9 in [RFC6550]. 601 In this case the flow comprises: 603 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 605 This case is assumed in the same RPL Domain. In the common parent, 606 the direction of RPI is changed (from increasing to decreasing the 607 rank). 609 While the 6LR nodes will update the RPI, no node needs to add or 610 remove the RPI, so no IP-in-IP headers are necessary. This may be 611 done regardless of where the destination is, as the included RPI will 612 be ignored by the receiver. 614 +-------------+-------+---------------+---------------+-----+-------+ 615 | Header | 6LN | 6LR | 6LR (common | 6LR | 6LN | 616 | | src | | parent) | | dst | 617 +-------------+-------+---------------+---------------+-----+-------+ 618 | Inserted | RPI | -- | -- | -- | -- | 619 | headers | | | | | | 620 | Removed | -- | -- | -- | -- | RPI | 621 | headers | | | | | | 622 | Re-added | -- | -- | -- | -- | -- | 623 | headers | | | | | | 624 | Modified | -- | RPI | RPI | -- | -- | 625 | headers | | (decreasing | (increasing | | | 626 | | | rank) | rank) | | | 627 | Untouched | -- | -- | -- | -- | -- | 628 | headers | | | | | | 629 +-------------+-------+---------------+---------------+-----+-------+ 631 Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 632 aware-leaf 634 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 636 In this case the flow comprises: 638 6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN 640 This situation is identical to the situation Section 5.9 642 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 644 In this case the flow comprises: 646 not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 648 The 6LR receives the packet from the the IPv6 node and inserts and 649 the RPI header encapsulated in IPv6-in-IPv6 header. The IP-in-IP 650 header is addressed to the destinion 6LN. 652 +--------+------+------------+------------+------------+------------+ 653 | Header | IPv6 | 6LR | common | 6LR | 6LN | 654 | | | | parent | | | 655 | | | | (6LR) | | | 656 +--------+------+------------+------------+------------+------------+ 657 | Insert | -- | IP-in- | -- | -- | -- | 658 | ed hea | | IP(RPI) | | | | 659 | ders | | | | | | 660 | Remove | -- | -- | -- | -- | IP-in- | 661 | d head | | | | | IP(RPI) | 662 | ers | | | | | | 663 | Re- | -- | -- | -- | -- | -- | 664 | added | | | | | | 665 | header | | | | | | 666 | s | | | | | | 667 | Modifi | -- | -- | IP-in- | IP-in- | -- | 668 | ed hea | | | IP(RPI) | IP(RPI) | | 669 | ders | | | | | | 670 | Untouc | -- | -- | -- | -- | -- | 671 | hed he | | | | | | 672 | aders | | | | | | 673 +--------+------+------------+------------+------------+------------+ 675 Storing: Summary of the use of headers from not-RPL-aware-leaf to 676 RPL-aware-leaf 678 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 680 In this case the flow comprises: 682 not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not- 683 RPL-aware 6LN (IPv6 node) 685 This flow is identical to Section 5.11 687 6. Non Storing mode 688 +--------------+------+------+-----------+---------------+ 689 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 690 +--------------+------+------+-----------+---------------+ 691 | Raf to root | Yes | No | No | -- | 692 | root to Raf | Yes | Yes | No | -- | 693 | root to ~Raf | No | Yes | Yes | 6LR | 694 | ~Raf to root | Yes | No | Yes | root | 695 | Raf to Int | Yes | No | Yes | root | 696 | Int to Raf | opt | Yes | Yes | dst | 697 | ~Raf to Int | Yes | No | Yes | root | 698 | Int to ~Raf | opt | Yes | Yes | 6LR | 699 | Raf to Raf | Yes | Yes | Yes | root/dst | 700 | Raf to ~Raf | Yes | Yes | Yes | root/6LR | 701 | ~Raf to Raf | Yes | Yes | Yes | root/6LN | 702 | ~Raf to ~Raf | Yes | Yes | Yes | root/6LR | 703 +--------------+------+------+-----------+---------------+ 705 Table 2: Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP 706 encapsulation 708 6.1. Example of Flow from RPL-aware-leaf to root 710 In non-storing mode the leaf node uses default routing to send 711 traffic to the root. The RPI header must be included to avoid/detect 712 loops. 714 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 716 This situation is the same case as storing mode. 718 +-------------------+-----+------+------+ 719 | Header | 6LN | 6LR | 6LBR | 720 +-------------------+-----+------+------+ 721 | Inserted headers | RPI | -- | -- | 722 | Removed headers | -- | -- | RPI | 723 | Re-added headers | -- | RPI | -- | 724 | Modified headers | -- | -- | -- | 725 | Untouched headers | -- | -- | -- | 726 +-------------------+-----+------+------+ 728 Non Storing: Summary of the use of headers from RPL-aware-leaf to 729 root 731 6.2. Example of Flow from root to RPL-aware-leaf 733 In this case the flow comprises: 735 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 736 The 6LBR will insert an RH3, and may optionally insert an RPI header. 737 No IP-in-IP header is necessary as the traffic originates with an RPL 738 aware node, the 6LBR. The destination is known to 6LBR because, the 739 root knows the whole topology in non-storing mode. 741 +-------------------+-----------------+------+----------+ 742 | Header | 6LBR | 6LR | 6LN | 743 +-------------------+-----------------+------+----------+ 744 | Inserted headers | (opt: RPI), RH3 | -- | -- | 745 | Removed headers | -- | -- | RH3,RPI | 746 | Re-added headers | -- | -- | -- | 747 | Modified headers | -- | RH3 | -- | 748 | Untouched headers | -- | -- | -- | 749 +-------------------+-----------------+------+----------+ 751 Non Storing: Summary of the use of headers from root to RPL-aware- 752 leaf 754 6.3. Example of Flow from root to not-RPL-aware-leaf 756 In this case the flow comprises: 758 root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node) 760 In 6LBR the RH3 is added, modified in each intermediate 6LR and it is 761 fully consumed in the last 6LR, but left there. If the RPI is left 762 present, the IPv6 node which does not understand it will drop it, 763 therefore the RPI should be removed before reaching the IPv6-only 764 node. To permit removal, an IP-in-IP header (hop-by-hop) or 765 addressed to the last 6LR is necessary. Due the complete knowledge 766 of the topology at the root, the 6LBR is able to address the IP-in-IP 767 header to the last 6LR. 769 Omitting the RPI entirely is therefore a better solution, as no IP- 770 in-IP header is necessary. 772 +-------------------+------+-----+------+ 773 | Header | 6LBR | 6LR | IPv6 | 774 +-------------------+------+-----+------+ 775 | Inserted headers | RH3 | -- | -- | 776 | Removed headers | -- | -- | -- | 777 | Re-added headers | -- | -- | -- | 778 | Modified headers | -- | RH3 | -- | 779 | Untouched headers | -- | -- | -- | 780 +-------------------+------+-----+------+ 782 Non Storing: Summary of the use of headers from root to not-RPL- 783 aware-leaf 785 6.4. Example of Flow from not-RPL-aware-leaf to root 787 In this case the flow comprises: 789 IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR) 791 In this case the RPI is added by the first 6LR, encapsulated in an 792 IP-in-IP header, and is not modified in the followings 6LRs. The RPI 793 and entire packet is consumed by the root. 795 +-------------------+------+----------------+------+----------------+ 796 | Header | IPv6 | 6LR1 | 6LR2 | 6LBR | 797 +-------------------+------+----------------+------+----------------+ 798 | Inserted headers | -- | IP-in-IP(RPI) | -- | -- | 799 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 800 | Re-added headers | -- | -- | -- | -- | 801 | Modified headers | -- | -- | -- | -- | 802 | Untouched headers | -- | IP-in-IP(RPI) | -- | -- | 803 +-------------------+------+----------------+------+----------------+ 805 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 806 root 808 6.5. Example of Flow from RPL-aware-leaf to Internet 810 In this case the flow comprises: 812 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 814 This case requires that the RPI be added, but removed by the 6LBR. 815 The 6LN must therefore add the RPI inside an IP-in-IP header, 816 addressed to the root. This case is identical to storing-mode case. 818 The IPv6 flow label should be set to zero to aid in compression, and 819 the 6LBR will set it to a non-zero value when sending towards the 820 Internet. 822 +-----------------+---------------+------+---------------+----------+ 823 | Header | 6LN | 6LR | 6LBR | Internet | 824 +-----------------+---------------+------+---------------+----------+ 825 | Inserted | IP-in-IP(RPI) | -- | -- | -- | 826 | headers | | | | | 827 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 828 | Re-added | -- | -- | -- | -- | 829 | headers | | | | | 830 | Modified | -- | -- | -- | -- | 831 | headers | | | | | 832 | Untouched | -- | RPI | -- | -- | 833 | headers | | | | | 834 +-----------------+---------------+------+---------------+----------+ 836 Non Storing: Summary of the use of headers from RPL-aware-leaf to 837 Internet 839 6.6. Example of Flow from Internet to RPL-aware-leaf 841 In this case the flow comprises: 843 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 845 The 6LBR must add an RH3 header. As the 6LBR will know the path and 846 address of the target not, it can address the IP-in-IP header to that 847 node. The 6LBR will zero the flow label upon entry in order to aid 848 compression. 850 The RPI may be added or not. 852 +----------+----------+-----------------------+---------------+-----+ 853 | Header | Internet | 6LBR | 6LR | 6LN | 854 +----------+----------+-----------------------+---------------+-----+ 855 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 856 | headers | | | | | 857 | Removed | -- | -- | IP-in-IP(RH3) | -- | 858 | headers | | | | | 859 | Re-added | -- | -- | -- | -- | 860 | headers | | | | | 861 | Modified | -- | -- | IP-in-IP(RH3) | -- | 862 | headers | | | | | 863 | Untouche | -- | -- | -- | -- | 864 | d | | | | | 865 | headers | | | | | 866 +----------+----------+-----------------------+---------------+-----+ 868 Non Storing: Summary of the use of headers from Internet to RPL- 869 aware-leaf 871 6.7. Example of Flow from not-RPL-aware-leaf to Internet 873 In this case the flow comprises: 875 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 877 In this case the flow label is recommended to be zero in the IPv6 878 node. As RPL headers are added in the IPv6 node, the first 6LN will 879 add an RPI header inside a new IP-in-IP header. The IP-in-IP header 880 will be addressed to the root. This case is identical to the 881 storing-mode case (Section 5.7). 883 +-----------------+------+---------------+---------------+----------+ 884 | Header | IPv6 | 6LR | 6LBR | Internet | 885 +-----------------+------+---------------+---------------+----------+ 886 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 887 | headers | | | | | 888 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 889 | Re-added | -- | -- | -- | -- | 890 | headers | | | | | 891 | Modified | -- | -- | -- | -- | 892 | headers | | | | | 893 | Untouched | -- | -- | -- | -- | 894 | headers | | | | | 895 +-----------------+------+---------------+---------------+----------+ 897 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 898 Internet 900 6.8. Example of Flow from Internet to non-RPL-aware-leaf 902 In this case the flow comprises: 904 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (IPv6 node) 906 The 6LBR must add an RH3 header inside an IP-in-IP header. The 6LBR 907 will know the path, and will recognize that the final node is not an 908 RPL capable node as it will have received the connectivity DAO from 909 the nearest 6LR. The 6LBR can therefore make the IP-in-IP header 910 destination be the last 6LR. The 6LBR will set to zero the flow 911 label upon entry in order to aid compression. 913 +----------+---------+-----------------------+---------------+------+ 914 | Header | Interne | 6LBR | 6LR | IPv6 | 915 | | t | | | | 916 +----------+---------+-----------------------+---------------+------+ 917 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 918 | headers | | | | | 919 | Removed | -- | -- | IP-in-IP(RH3, | -- | 920 | headers | | | RPI) | | 921 | Re-added | -- | -- | -- | -- | 922 | headers | | | | | 923 | Modified | -- | -- | -- | -- | 924 | headers | | | | | 925 | Untouche | -- | -- | -- | -- | 926 | d | | | | | 927 | headers | | | | | 928 +----------+---------+-----------------------+---------------+------+ 930 NonStoring: Summary of the use of headers from Internet to non-RPL- 931 aware-leaf 933 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 935 In this case the flow comprises: 937 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 939 This case involves only nodes in same RPL Domain. The originating 940 node will add an RPI header to the original packet, and send the 941 packet upwards. 943 The originating node could put the RPI into an IP-in-IP header 944 addressed to the root, so that the 6LBR can remove that header. 946 The 6LBR will need to insert an RH3 header, which requires that it 947 add an IP-in-IP header. It may be able to remove the RPI if it was 948 contained in an IP-in-IP header addressed to it. Otherwise, there 949 may be an RPI header buried inside the inner IP header, which should 950 get ignored. 952 Networks that use the RPL P2P extension [RFC6997] are essentially 953 non-storing DODAGs and fall into this scenario. 955 +----------+---------------+--------------+-----+-------------------+ 956 | Header | 6LN src | 6LBR | 6LR | 6LN dst | 957 +----------+---------------+--------------+-----+-------------------+ 958 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3 | -- | -- | 959 | headers | | to 6LN,RPI) | | | 960 | Removed | -- | -- | -- | IP-in-IP(RH3,RPI) | 961 | headers | | | | | 962 | Re-added | -- | -- | -- | -- | 963 | headers | | | | | 964 | Modified | -- | -- | -- | -- | 965 | headers | | | | | 966 | Untouche | -- | -- | -- | -- | 967 | d | | | | | 968 | headers | | | | | 969 +----------+---------------+--------------+-----+-------------------+ 971 Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 972 aware-leaf 974 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 976 In this case the flow comprises: 978 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware (IPv6 node) 980 As in the previous case, the 6LN will insert an RPI header which MUST 981 be in an IP-in-IP header addressed to the root so that the 6LBR can 982 remove this RPI. The 6LBR will then insert an RH3 inside a new IP- 983 in-IP header addressed to the 6LN above the destination node. 985 +-----------+---------------+---------------+----------------+------+ 986 | Header | 6LN | 6LBR | 6LR | IPv6 | 987 +-----------+---------------+---------------+----------------+------+ 988 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- | 989 | headers | | opt RPI) | | | 990 | Removed | -- | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | 991 | headers | | | opt RPI) | | 992 | Re-added | -- | -- | -- | -- | 993 | headers | | | | | 994 | Modified | -- | -- | -- | -- | 995 | headers | | | | | 996 | Untouched | -- | -- | -- | -- | 997 | headers | | | | | 998 +-----------+---------------+---------------+----------------+------+ 1000 Non Storing: Summary of the use of headers from RPL-aware-leaf to 1001 not-RPL-aware-leaf 1003 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 1005 In this case the flow comprises: 1007 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 1009 This scenario is mostly identical to the previous one. The RPI is 1010 added by the first 6LR inside an IP-in-IP header addressed to the 1011 root. The 6LBR will remove this RPI, and add it's own IP-in-IP 1012 header containing an RH3 header. 1014 +------------+------+---------------+---------------+---------------+ 1015 | Header | IPv6 | 6LR | 6LBR | 6LN | 1016 +------------+------+---------------+---------------+---------------+ 1017 | Inserted | -- | IP-in-IP(RPI) | IP-in-IP(RH3) | -- | 1018 | headers | | | | | 1019 | Removed | -- | IP-in-IP(RPI) | -- | IP-in-IP(RH3) | 1020 | headers | | | | | 1021 | Re-added | -- | -- | -- | -- | 1022 | headers | | | | | 1023 | Modified | -- | -- | -- | -- | 1024 | headers | | | | | 1025 | Untouched | -- | -- | -- | -- | 1026 | headers | | | | | 1027 +------------+------+---------------+---------------+---------------+ 1029 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1030 RPL-aware-leaf 1032 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 1034 In this case the flow comprises: 1036 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 1037 (IPv6 node) 1039 This scenario is the combination of the previous two cases. 1041 +----------+-----+-------------+--------------+--------------+------+ 1042 | Header | IPv | 6LR | 6LBR | 6LR | IPv6 | 1043 | | 6 | | | | | 1044 +----------+-----+-------------+--------------+--------------+------+ 1045 | Inserted | -- | IP-in- | IP-in- | -- | -- | 1046 | headers | | IP(RPI) | IP(RH3) | | | 1047 | Removed | -- | -- | IP-in- | IP-in- | -- | 1048 | headers | | | IP(RPI) | IP(RH3, opt | | 1049 | | | | | RPI) | | 1050 | Re-added | -- | -- | -- | -- | -- | 1051 | headers | | | | | | 1052 | Modified | -- | -- | -- | -- | -- | 1053 | headers | | | | | | 1054 | Untouche | -- | -- | -- | -- | -- | 1055 | d | | | | | | 1056 | headers | | | | | | 1057 +----------+-----+-------------+--------------+--------------+------+ 1059 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1060 not-RPL-aware-leaf 1062 7. Observations about the problem 1064 7.1. Storing mode 1066 In the completely general storing case, which includes not-RPL aware 1067 leaf nodes, it is not possible for a sending node to know if the 1068 destination is RPL aware, and therefore it must always use hop-by-hop 1069 IP-in-IP encapsulation, and it can never omit the IP-in-IP 1070 encapsulation. See table Table 1 1072 The simplest fully general approach for storing mode is to always put 1073 in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch] 1074 shows that this hop-by-hop IP-in-IP header can be compressed down to 1075 {TBD} bytes. 1077 There are potential significant advantages to having a single code 1078 path that always processes IP-in-IP headers with no options. 1080 If all RPL aware nodes can be told/configured that there are no non- 1081 RPL aware leaf nodes, then the only case where an IP-in-IP header is 1082 needed is when communicating outside the LLN. The 6LBR knows well 1083 when the communication is from the outside, and the 6LN can tell by 1084 comparing the destination address to the prefix provided in the PIO. 1085 If it is known that there are no communications outside the RPL 1086 domain (noting that the RPL domain may well extend to outside the 1087 LLN), then RPI headers can be included in all packets, and IP-in-IP 1088 headers are *never* needed. This may be significantly advantageous 1089 in relatively closed systems such as in building or industrial 1090 automation. Again, there are advantages to having a single code 1091 path. 1093 In order to support the above two cases with full generality, the 1094 different situations (always do IP-in-IP vs never use IP-in-IP) 1095 should be signaled in the RPL protocol itself. 1097 7.2. Non-Storing mode 1099 In the non-storing case, dealing with non-RPL aware leaf nodes is 1100 much easier as the 6LBR (DODAG root) has complete knowledge about the 1101 connectivity of all DODAG nodes, and all traffic flows through the 1102 root node. 1104 The 6LBR can recognize non-RPL aware leaf nodes because it will 1105 receive a DAO about that node from the 6LN immediately above that 1106 node. This means that the non-storing mode case can avoid ever using 1107 hop-by-hop IP-in-IP headers. 1109 It is unclear what it would mean for an RH3 header to be present in a 1110 hop-by-hop IP-in-IP header. The receiving node ought to consume the 1111 IP-in-IP header, and therefore consume the RH3 as well, and then 1112 attempt to send the packet again. But intermediate 6LN nodes would 1113 not know how to forward the packet (because they do not save the 1114 sate), so the RH3 would need to be retained. This is a new kind of 1115 IPv6 packet processing. Therefore it may be that on the outbound leg 1116 of non-storing RPL networks, that hop-by-hop IP-in-IP header can NOT 1117 be used. 1119 [I-D.ietf-roll-routing-dispatch] shows how the destination=root, and 1120 destination=6LN IP-in-IP header can be compressed down to {TBD} 1121 bytes. 1123 Unlike in the storing mode case, there is no need for all nodes to 1124 know about the existence of non-RPL aware nodes. Only the 6LBR needs 1125 to change when there are non-RPL aware nodes. Further, in the non- 1126 storing case, the 6LBR is informed by the DAOs when there are non-RPL 1127 aware nodes. 1129 8. 6LoRH Compression cases 1131 The [I-D.ietf-roll-routing-dispatch] proposes a compression method 1132 for RPI, RH3 and IPv6-in-IPv6. 1134 In Storing Mode, for the examples of Flow from RPL-aware-leaf to non- 1135 RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise 1136 an IP-in-IP and RPI compression headers. The type of this case is 1137 critical since IP-in-IP is encapsulating a RPI header. 1139 +--+-----+---+--------------+-----------+-------------+-------------+ 1140 |1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC | 1141 +--+-----+---+--------------+-----------+-------------+-------------+ 1143 Figure 3: Critical IP-in-IP (RPI). 1145 9. IANA Considerations 1147 There are no IANA considerations related to this document. 1149 10. Security Considerations 1151 The security considerations covering of [RFC6553] and [RFC6554] apply 1152 when the packets get into RPL Domain. 1154 11. Acknowledgments 1156 This work is partially funded by the FP7 Marie Curie Initial Training 1157 Network (ITN) METRICS project (grant agreement No. 607728). 1159 The authors would like to acknowledge the review, feedback, and 1160 comments of Robert Cragie, Simon Duquennoy, Cenk Guendogan, Peter van 1161 der Stok, Xavier Vilajosana and Thomas Watteyne. 1163 12. References 1165 12.1. Normative References 1167 [I-D.ietf-6man-rfc2460bis] 1168 Deering, D. and R. Hinden, "Internet Protocol, Version 6 1169 (IPv6) Specification", draft-ietf-6man-rfc2460bis-05 (work 1170 in progress), June 2016. 1172 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1173 Requirement Levels", BCP 14, RFC 2119, 1174 DOI 10.17487/RFC2119, March 1997, 1175 . 1177 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1178 (IPv6) Specification", RFC 2460, December 1998. 1180 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1181 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1182 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1183 Low-Power and Lossy Networks", RFC 6550, 1184 DOI 10.17487/RFC6550, March 2012, 1185 . 1187 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 1188 Power and Lossy Networks (RPL) Option for Carrying RPL 1189 Information in Data-Plane Datagrams", RFC 6553, 1190 DOI 10.17487/RFC6553, March 2012, 1191 . 1193 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 1194 Routing Header for Source Routes with the Routing Protocol 1195 for Low-Power and Lossy Networks (RPL)", RFC 6554, 1196 DOI 10.17487/RFC6554, March 2012, 1197 . 1199 12.2. Informative References 1201 [I-D.ietf-6tisch-architecture] 1202 Thubert, P., "An Architecture for IPv6 over the TSCH mode 1203 of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work 1204 in progress), June 2016. 1206 [I-D.ietf-roll-routing-dispatch] 1207 Thubert, P., Bormann, C., Toutain, L., and R. Cragie, 1208 "6LoWPAN Routing Header", draft-ietf-roll-routing- 1209 dispatch-00 (work in progress), March 2016. 1211 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1212 Control Message Protocol (ICMPv6) for the Internet 1213 Protocol Version 6 (IPv6) Specification", RFC 4443, 1214 DOI 10.17487/RFC4443, March 2006, 1215 . 1217 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1218 Bormann, "Neighbor Discovery Optimization for IPv6 over 1219 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1220 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1221 . 1223 [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and 1224 J. Martocci, "Reactive Discovery of Point-to-Point Routes 1225 in Low-Power and Lossy Networks", RFC 6997, 1226 DOI 10.17487/RFC6997, August 2013, 1227 . 1229 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 1230 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 1231 2014, . 1233 [Second6TischPlugtest] 1234 "2nd 6Tisch Plugtest", . 1237 Authors' Addresses 1239 Maria Ines Robles 1240 Ericsson 1241 Hirsalantie 11 1242 Jorvas 02420 1243 Finland 1245 Email: maria.ines.robles@ericsson.com 1247 Michael C. Richardson 1248 Sandelman Software Works 1249 470 Dawson Avenue 1250 Ottawa, ON K1Z 5V7 1251 CA 1253 Email: mcr+ietf@sandelman.ca 1254 URI: http://www.sandelman.ca/ 1256 Pascal Thubert 1257 Cisco Systems, Inc 1258 Village d'Entreprises Green Side 400, Avenue de Roumanille 1259 Batiment T3, Biot - Sophia Antipolis 06410 1260 France 1262 Email: pthubert@cisco.com