idnits 2.17.00 (12 Aug 2021) /tmp/idnits39256/draft-richardson-roll-useofrplinfo-2460bis-00.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 18, 2016) is 2133 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for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: draft-ietf-6man-rfc2460bis has been published as RFC 8200 ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: draft-ietf-6tisch-architecture has been published as RFC 9030 == Outdated reference: draft-ietf-roll-routing-dispatch has been published as RFC 8138 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 19, 2017 SSW 6 P. Thubert 7 Cisco 8 July 18, 2016 10 When to use RFC 6553, 6554 and IPv6-in-IPv6 11 draft-richardson-roll-useofrplinfo-2460bis-00 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 19, 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 3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4 59 4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 8 61 5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 9 62 5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 10 63 5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 10 64 5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 11 65 5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 11 66 5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 12 67 5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 12 68 5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 13 69 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 14 70 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 15 71 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 15 72 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 73 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 16 74 6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 16 75 6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 17 76 6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 17 77 6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 18 78 6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 19 79 6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 19 80 6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 20 81 6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 21 82 6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 21 83 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 22 84 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 23 85 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 24 86 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 87 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 24 88 7. Observations about the problem . . . . . . . . . . . . . . . 25 89 7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 25 90 7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 26 91 8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 26 92 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 93 10. Security Considerations . . . . . . . . . . . . . . . . . . . 27 94 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 95 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 96 12.1. Normative References . . . . . . . . . . . . . . . . . . 27 97 12.2. Informative References . . . . . . . . . . . . . . . . . 28 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 100 1. Introduction 102 RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) 103 [RFC6550] is a routing protocol for constrained networks. RFC 6553 104 [RFC6553] defines the "RPL option" (RPI), carried within the IPv6 105 Hop-by-Hop header to quickly identify inconsistencies (loops) in the 106 routing topology. RFC 6554 [RFC6554] defines the "RPL Source Route 107 Header" (RH3), an IPv6 Extension Header to deliver datagrams within a 108 RPL routing domain, particularly in non-storing mode. 110 These various items are referred to as RPL artifacts, and they are 111 seen on all of the data-plane traffic that occurs in RPL routed 112 networks; they do not in general appear on the RPL control plane 113 traffic at all which is mostly hop-by-hop traffic (one exception 114 being DAO messages in non-storing mode). 116 It has become clear from attempts to do multi-vendor 117 interoperability, and from a desire to compress as many of the above 118 artifacts as possible that not all implementors agree when artifacts 119 are necessary, or when they can be safely omitted, or removed. 121 An interim meeting went through the 24 cases defined here to discover 122 if there were any shortcuts, and this document is the result of that 123 discussion. This document should not be defining anything new, but 124 it may clarify what is correct and incorrect behaviour. 126 The related document A Routing Header Dispatch for 6LoWPAN (6LoRH) 127 [I-D.ietf-roll-routing-dispatch] defines a method to compress RPL 128 Option information and Routing Header type 3 (RFC6554) and an 129 efficient IP-in-IP technique. Uses cases proposed for the 130 [Second6TischPlugtest] involving 6loRH. 132 2. Terminology and Requirements Language 134 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 135 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 136 document are to be interpreted as described in RFC 2119 [RFC2119]. 138 Terminology defined in [RFC7102] applies to this document: LBR, LLN, 139 RPL, RPL Domain and ROLL. 141 3. Sample/reference topology 143 A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone 144 Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf 145 logically organized in a DODAG structure (Destination Oriented 146 Directed Acyclic Graph). 148 RPL defines the RPL Control messages (control plane), a new ICMPv6 149 [RFC4443] message with Type 155. DIS (DODAG Information 150 Solicitation), DIO (DODAG Information Object) and DAO (Destination 151 Advertisement Object) messages are all RPL Control messages but with 152 different Code values. 154 RPL supports two modes of Downward traffic: in storing mode (RPL-SM), 155 it is fully stateful or an in non-storing (RPL-NSM), it is fully 156 source routed. A RPL Instance is either fully storing or fully non- 157 storing, i.e. a RPL Instance with a combination of storing and non- 158 storing nodes is not supported with the current specifications at the 159 time of writing this document. 161 +--------------+ 162 | Upper Layers | 163 | | 164 +--------------+ 165 | RPL | 166 | | 167 +--------------+ 168 | ICMPv6 | 169 | | 170 +--------------+ 171 | IPv6 | 172 | | 173 +--------------+ 174 | 6LoWPAN | 175 | | 176 +--------------+ 177 | PHY-MAC | 178 | | 179 +--------------+ 181 Figure 1: RPL Stack. 183 +---------+ 184 +---+Internet | 185 | +---------+ 186 | 187 +----+--+ 188 | DODAG | node:01 189 +---------+ Root +----------+ 190 | | 6LBR | | 191 | +----+--+ | 192 | | | 193 | | | 194 ... ... ... 195 | | | 196 +-----+-+ +--+---+ +--+---+ 197 |6LR | | | | | 198 +-----+ | | | | | 199 | | 11 | | 12 | | 13 +------+ 200 | +-----+-+ +-+----+ +-+----+ | 201 | | | | | 202 | | | | | 203 | 21 | 22 | 23 | 24 | 25 204 +-+---+ +-+---+ +--+--+ +- --+ +---+-+ 205 |Leaf | | | | | |Leaf| |Leaf | 206 | 6LN | | | | | | 6LN| | 6LN | 207 +-----+ +-----+ +-----+ +----+ +-----+ 209 Figure 2: A reference RPL Topology. 211 The numbers in or above the nodes are there so that they may be 212 referenced in subsequent sections. In the figure 2, 6LN can be a 213 router or a host. The 6LN leaf marked as (21) and (25) are routers. 214 The leaf marked 6LN (24) is a device which does not speak RPL at all 215 (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/DAC and 216 efficient-ND only to participate in the network [RFC6775]. In the 217 document this leaf (24) is mentioned as well as IPv6 node. The 6LBR 218 in the figure is the root of the Global DODAG. 220 This document is in part motivated by the work that is ongoing at the 221 6TiSCH working group. The 6TiSCH architecture 222 [I-D.ietf-6tisch-architecture] draft explains the network 223 architecture of a 6TiSCH network. This architecture is used for the 224 remainder of this document. 226 The scope of the 6TiSCH (IPv6 over the TSCH mode of IEEE 802.15.4e) 227 Architecture is a Backbone Link that federates multiple LLNs (mesh) 228 as a single IPv6 Multi-Link Subnet. Each LLN in the subnet is 229 anchored at a Backbone Router (6BBR). The Backbone Routers 230 interconnect the LLNs over the Backbone Link and emulate that the LLN 231 nodes are present on the Backbone thus creating a so-called: Multi- 232 Link Subnet. An LLN node can move freely from an LLN anchored at a 233 Backbone Router to another LLN anchored at the same or a different 234 Backbone Router inside the Multi-Link Subnet and conserve its 235 addresses. 237 +---------+ 238 +---+Internet | 239 | +---------+ 240 | 241 | 242 +-----+ 243 | | Border Router to the RPL domain 244 | | (may be a RPL virtual root) 245 +-----+ 246 | 247 | Backbone 248 +-------------------+-------------------+ 249 | | | 250 +-----+ +-----+ +-----+ 251 | | Backbone | | Backbone | | Backbone 252 | | router | | router | | router 253 +|---|+ +-|||-+ +-[_]-+ 254 | | PCI-exp / | \ USB | Ethernet 255 ( ) ( ) ( )( )( ) (6LBR == RPL DODAG root) 256 o o o o o o o o o o o o 257 o o o o o o o o o o o o o o o o 258 o o o o o o o o o o 6LR == RPL router) o o 259 o o o o o o o z 260 o o o o o o (6LoWPAN Host) 262 <----------------------- RPL Instances ------------------------> 264 Figure 3: RPL domain architecture 266 4. Use cases 268 In data plane context a combination of RFC6553, RFC6554 and IPv6-in- 269 IPv6 encapsulation is going to be analyzed for the following traffic 270 flows. 272 This version of the document assumes the changes in 273 [I-D.ietf-6man-rfc2460bis] are passed. 275 RPL-aware-leaf to root 277 root to RPL-aware-leaf 279 not-RPL-aware-leaf to root 281 root to not-RPL-aware-leaf 283 RPL-aware-leaf to Internet 285 Internet to RPL-aware-leaf 287 not-RPL-aware-leaf to Internet 289 Internet to not-RPL-aware-leaf 291 RPL-aware-leaf to RPL-aware-leaf (storing and non-storing) 293 RPL-aware-leaf to not-RPL-aware-leaf (non-storing) 295 not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing) 297 not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing) 299 This document assumes the rule that a Header cannot be inserted or 300 removed on the fly inside an IPv6 packet that is being routed. This 301 is a fundamental precept of the IPv6 architecture as outlined in 302 [RFC2460] is that Extensions may not be added or removed except by 303 the sender or the receiver. (A revision to RFC2460 considered 304 changing this rule, but has kept it) 306 But, options in the Hop-by-Hop option which are marked with option 307 type 01 ([RFC2460] section 4.2 and [I-D.ietf-6man-rfc2460bis]) SHOULD 308 be ignored when received by a host or router which does not 309 understand that option. 311 This means that in general, any packet that leaves the RPL domain of 312 an LLN (or leaves the LLN entirely) will NOT be discarded, even if it 313 has the [RFC6553] RPL Option Header known as the RPI or [RFC6554] 314 SRH3 Extension Header (S)RH3. 316 With abolition of one of these rules it means that the RPI Hop-by-Hop 317 option MAY be left in place even if the end host does host understand 318 it. This collapses many of the cases above (where it says "or") 320 An intermediate router that needs to add an extension header (SHR3 or 321 RPI Option) must encapsulate the packet in an (additional) outer IP 322 header where the new header can be placed. 324 This also means that a Header can only be removed by an intermediate 325 router if it is placed in an encapsulating IPv6 Header, and in that 326 case, the whole encapsulating header must be removed - a replacement 327 may be added. Further, an intermediate router can only remove such 328 an outer header if that outer header has the router as the 329 destination! 331 Both RPI and RH3 headers may be modified by routers on the path of 332 the packet without the need to add to remove an encapsulating header. 333 Both headers were designed with this modification in mind, and both 334 the RPL RH and the RPL option are marked mutable but recoverable, so 335 an IPsec AH security header can be applied across these headers, but 336 it may not secure all the values in those headers. 338 RPI should be present in every single RPL data packet. There is one 339 exception in non-storing mode: when a packet is going down from the 340 root. In a downward non-storing mode, the entire route is written, 341 so there can be no loops by construction, nor any confusion about 342 which forwarding table to use. There may be cases (such as in 343 6tisch) where the instanceID may still be needed to pick an 344 appropriate priority or channel at each hop. 346 In tables, the term "RPL aware leaf" is has been shortened to "Raf", 347 and "not-RPL aware leaf" has been shortened to "~Raf" to make the 348 table fit in available space. 350 The earlier examples are more complete to make sure that the process 351 is clear, while later examples are more consise. 353 5. Storing mode 355 This table summarizes what headers are needed in the following 356 scenarios, and indicates the IP-in-IP header must be inserted on a 357 hop-by-hop basis, and when it can target the destination node 358 directly. There are three possible situations: hop-by-hop necessary 359 (indicated by "hop"), or destination address possible (indicated by 360 "dst"). In all cases hop by hop can be used. In cases where no IP- 361 in-IP header is needed, the column is left blank. 363 The leaf can be a router 6LR or a host indicated as 6LN. 365 +--------------+-------+-------+-----------+---------------+ 366 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 367 +--------------+-------+-------+-----------+---------------+ 368 | Raf to root | Yes | No | No | -- | 369 | root to Raf | Yes | No | No | -- | 370 | root to ~Raf | Yes | No | Yes | hop | 371 | ~Raf to root | Yes | No | Yes | root | 372 | Raf to Int | Yes | No | Yes | root | 373 | Int to Raf | Yes | No | Yes | raf | 374 | ~Raf to Int | Yes | No | Yes | root | 375 | Int to ~Raf | Yes | No | Yes | hop | 376 | Raf to Raf | Yes | No | No | -- | 377 | Raf to ~Raf | Yes | No | Yes | hop | 378 | ~Raf to Raf | Yes | No | Yes | dst | 379 | ~Raf to ~Raf | Yes | No | Yes | hop | 380 +--------------+-------+-------+-----------+---------------+ 382 Table 1: Headers needed in Storing mode: RPI, RH3, IP-in-IP 383 encapsulation 385 5.1. Example of Flow from RPL-aware-leaf to root 387 In storing mode, RFC 6553 (RPI) is used to send RPL Information 388 instanceID and rank information. 390 As stated in Section 16.2 of [RFC6550] a RPL-aware-leaf node does 391 not generally issue DIO messages; a leaf node accepts DIO messages 392 from upstream. (When the inconsistency in routing occurs, a leaf 393 node will generate a DIO with an infinite rank, to fix it). It may 394 issue DAO and DIS messages though it generally ignores DAO and DIS 395 messages. 397 In storing mode, RFC 6553 (RPI) is used to send RPL Information 398 instanceID and rank information. 400 In this case the flow comprises: 402 RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR) 404 As it was mentioned In this document 6LRs, 6LBR are always full- 405 fledge RPL routers, and are the RPL root node. 407 The 6LN inserts the RPI header, and sends the packet to 6LR which 408 decrements the rank in RPI and sends the packet up. When the packet 409 arrives at 6LBR, the RPI is removed and the packet is processed. 411 No IP-in-IP header is required. 413 The RPI header can be removed by the 6LBR because the packet is 414 addressed to the 6LBR. The 6LN must know that it is communicating 415 with the 6LBR in order to be able to make use of this scenario. The 416 6LN can know the address of the 6LBR because it knows the address of 417 the root via the DODAGID in the DIO messages. 419 +-------------------+-----+------+------+ 420 | Header | 6LN | 6LR | 6LBR | 421 +-------------------+-----+------+------+ 422 | Inserted headers | RPI | -- | -- | 423 | Removed headers | -- | -- | RPI | 424 | Re-added headers | -- | -- | -- | 425 | Modified headers | -- | RPI | -- | 426 | Untouched headers | -- | -- | -- | 427 +-------------------+-----+------+------+ 429 Storing: Summary of the use of headers from RPL-aware-leaf to root 431 5.2. Example of Flow from root to RPL-aware-leaf 433 In this case the flow comprises: 435 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 437 In this case the 6LBR insert RPI header and send the packet down, the 438 6LR is going to increment the rank in RPI (examines instanceID for 439 multiple tables), the packet is processed in 6LN and RPI removed. 441 No IP-in-IP header is required. 443 +-------------------+------+-------+------+ 444 | Header | 6LBR | 6LR | 6LN | 445 +-------------------+------+-------+------+ 446 | Inserted headers | RPI | -- | -- | 447 | Removed headers | -- | -- | RPI | 448 | Re-added headers | -- | -- | -- | 449 | Modified headers | -- | RPI | -- | 450 | Untouched headers | -- | -- | -- | 451 +-------------------+------+-------+------+ 453 Storing: Summary of the use of headers from root to RPL-aware-leaf 455 5.3. Example of Flow from root to not-RPL-aware-leaf 457 In this case the flow comprises: 459 root (6LBR)--> 6LR --> not-RPL-aware-leaf (6LN) 460 As the RPI extension can be ignored by the not-RPL-aware leaf, this 461 situation is identical to the previous scenario. 463 +-------------------+------+-----+------+ 464 | Header | 6LBR | 6LR | IPv6 | 465 +-------------------+------+-----+------+ 466 | Inserted headers | -- | -- | -- | 467 | Removed headers | -- | -- | -- | 468 | Re-added headers | -- | -- | -- | 469 | Modified headers | -- | -- | -- | 470 | Untouched headers | -- | -- | -- | 471 +-------------------+------+-----+------+ 473 Storing: Summary of the use of headers from root to not-RPL-aware- 474 leaf 476 5.4. Example of Flow from not-RPL-aware-leaf to root 478 In this case the flow comprises: 480 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 482 When the packet arrives from IPv6 node to 6LR, the 6LR will insert an 483 RPI header, encapsuladed in a IPv6-in-IPv6 header. The IPv6-in-IPv6 484 header can be addressed to the next hop, or to the root. The root 485 removes the header and processes the packet. 487 +-------------------+------+----------------+---------------+ 488 | Header | IPv6 | 6LR | 6LBR | 489 +-------------------+------+----------------+---------------+ 490 | Inserted headers | -- | IP-in-IP(RPI) | -- | 491 | Removed headers | -- | -- | IP-in-IP(RPI) | 492 | Re-added headers | -- | -- | -- | 493 | Modified headers | -- | -- | -- | 494 | Untouched headers | -- | -- | -- | 495 +-------------------+------+----------------+---------------+ 497 Storing: Summary of the use of headers from not-RPL-aware-leaf to 498 root 500 5.5. Example of Flow from RPL-aware-leaf to Internet 502 RPL information from RFC 6553 MAY go out to Internet as it will be 503 ignored by nodes which have not been configured to be RPI aware. 505 In this case the flow comprises: 507 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 508 No IP-in-IP header is required. 510 +-------------------+------+------+------+----------+ 511 | Header | 6LN | 6LR | 6LBR | Internet | 512 +-------------------+------+------+------+----------+ 513 | Inserted headers | RPI | -- | -- | -- | 514 | Removed headers | -- | -- | -- | -- | 515 | Re-added headers | -- | -- | -- | -- | 516 | Modified headers | -- | RPI | -- | -- | 517 | Untouched headers | -- | -- | -- | -- | 518 +-------------------+------+------+------+----------+ 520 Storing: Summary of the use of headers from RPL-aware-leaf to 521 Internet 523 5.6. Example of Flow from Internet to RPL-aware-leaf 525 In this case the flow comprises: 527 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 529 When the packet arrives from Internet to 6LBR the RPI header is added 530 in a outer IPv6-in-IPv6 header and sent to 6LR, which modifies the 531 rank in the RPI. When the packet arrives at 6LN the RPI header is 532 removed and the packet processed. 534 +-----------------+----------+---------------+------+---------------+ 535 | Header | Internet | 6LBR | 6LR | 6LN | 536 +-----------------+----------+---------------+------+---------------+ 537 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 538 | headers | | | | | 539 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 540 | Re-added | -- | -- | -- | -- | 541 | headers | | | | | 542 | Modified | -- | -- | RPI | -- | 543 | headers | | | | | 544 | Untouched | -- | -- | -- | -- | 545 | headers | | | | | 546 +-----------------+----------+---------------+------+---------------+ 548 Storing: Summary of the use of headers from Internet to RPL-aware- 549 leaf 551 5.7. Example of Flow from not-RPL-aware-leaf to Internet 553 In this case the flow comprises: 555 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 556 The 6LR node will add an IP-in-IP(RPI) header addressed either to the 557 root, or hop-by-hop such that the root can remove the RPI header 558 before passing upwards. 560 The originating node will ideally leave the IPv6 flow label as zero 561 so that it can be better compressed through the LLN, and the 6LBR 562 will set the flow label to a non-zero value when sending to the 563 Internet. 565 +-----------------+------+---------------+---------------+----------+ 566 | Header | 6LN | 6LR | 6LBR | Internet | 567 +-----------------+------+---------------+---------------+----------+ 568 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 569 | headers | | | | | 570 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 571 | Re-added | -- | -- | -- | -- | 572 | headers | | | | | 573 | Modified | -- | -- | -- | -- | 574 | headers | | | | | 575 | Untouched | -- | -- | -- | -- | 576 | headers | | | | | 577 +-----------------+------+---------------+---------------+----------+ 579 Storing: Summary of the use of headers from not-RPL-aware-leaf to 580 Internet 582 5.8. Example of Flow from Internet to non-RPL-aware-leaf 584 In this case the flow comprises: 586 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) 588 The 6LBR will have to add an RPI header within an IP-in-IP header. 589 The IP-in-IP can be addressed to the not-RPL-aware-leaf, leaving the 590 RPI inside. 592 The 6LBR MAY set the flow label on the inner IP-in-IP header to zero 593 in order to aid in compression, as the packet will not emerge again 594 from the LLN. 596 +-----------------+----------+---------------+---------------+------+ 597 | Header | Internet | 6LBR | 6LR | IPv6 | 598 +-----------------+----------+---------------+---------------+------+ 599 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 600 | headers | | | | | 601 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 602 | Re-added | -- | -- | -- | -- | 603 | headers | | | | | 604 | Modified | -- | -- | -- | -- | 605 | headers | | | | | 606 | Untouched | -- | -- | -- | -- | 607 | headers | | | | | 608 +-----------------+----------+---------------+---------------+------+ 610 Storing: Summary of the use of headers from Internet to non-RPL- 611 aware-leaf 613 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 615 In [RFC6550] RPL allows a simple one-hop optimization for both 616 storing and non-storing networks. A node may send a packet destined 617 to a one-hop neighbor directly to that node. Section 9 in [RFC6550]. 619 In this case the flow comprises: 621 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 623 This case is assumed in the same RPL Domain. In the common parent, 624 the direction of RPI is changed (from increasing to decreasing the 625 rank). 627 While the 6LR nodes will update the RPI, no node needs to add or 628 remove the RPI, so no IP-in-IP headers are necessary. This may be 629 done regardless of where the destination is, as the included RPI will 630 be ignored by the receiver. 632 +-------------+-------+---------------+---------------+-----+-------+ 633 | Header | 6LN | 6LR | 6LR (common | 6LR | 6LN | 634 | | src | | parent) | | dst | 635 +-------------+-------+---------------+---------------+-----+-------+ 636 | Inserted | RPI | -- | -- | -- | -- | 637 | headers | | | | | | 638 | Removed | -- | -- | -- | -- | RPI | 639 | headers | | | | | | 640 | Re-added | -- | -- | -- | -- | -- | 641 | headers | | | | | | 642 | Modified | -- | RPI | RPI | -- | -- | 643 | headers | | (decreasing | (increasing | | | 644 | | | rank) | rank) | | | 645 | Untouched | -- | -- | -- | -- | -- | 646 | headers | | | | | | 647 +-------------+-------+---------------+---------------+-----+-------+ 649 Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 650 aware-leaf 652 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 654 In this case the flow comprises: 656 6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN 658 This situation is identical to the situation Section 5.9 660 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 662 In this case the flow comprises: 664 not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 666 The 6LR receives the packet from the the IPv6 node and inserts and 667 the RPI header encapsulated in IPv6-in-IPv6 header. The IP-in-IP 668 header is addressed to the destinion 6LN. 670 +--------+------+------------+------------+------------+------------+ 671 | Header | IPv6 | 6LR | common | 6LR | 6LN | 672 | | | | parent | | | 673 | | | | (6LR) | | | 674 +--------+------+------------+------------+------------+------------+ 675 | Insert | -- | IP-in- | -- | -- | -- | 676 | ed hea | | IP(RPI) | | | | 677 | ders | | | | | | 678 | Remove | -- | -- | -- | -- | IP-in- | 679 | d head | | | | | IP(RPI) | 680 | ers | | | | | | 681 | Re- | -- | -- | -- | -- | -- | 682 | added | | | | | | 683 | header | | | | | | 684 | s | | | | | | 685 | Modifi | -- | -- | IP-in- | IP-in- | -- | 686 | ed hea | | | IP(RPI) | IP(RPI) | | 687 | ders | | | | | | 688 | Untouc | -- | -- | -- | -- | -- | 689 | hed he | | | | | | 690 | aders | | | | | | 691 +--------+------+------------+------------+------------+------------+ 693 Storing: Summary of the use of headers from not-RPL-aware-leaf to 694 RPL-aware-leaf 696 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 698 In this case the flow comprises: 700 not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not- 701 RPL-aware 6LN (IPv6 node) 703 This flow is identical to Section 5.11 705 6. Non Storing mode 706 +--------------+------+------+-----------+---------------+ 707 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 708 +--------------+------+------+-----------+---------------+ 709 | Raf to root | Yes | No | No | -- | 710 | root to Raf | Yes | Yes | No | -- | 711 | root to ~Raf | No | Yes | Yes | 6LR | 712 | ~Raf to root | Yes | No | Yes | root | 713 | Raf to Int | Yes | No | Yes | root | 714 | Int to Raf | opt | Yes | Yes | dst | 715 | ~Raf to Int | Yes | No | Yes | root | 716 | Int to ~Raf | opt | Yes | Yes | 6LR | 717 | Raf to Raf | Yes | Yes | Yes | root/dst | 718 | Raf to ~Raf | Yes | Yes | Yes | root/6LR | 719 | ~Raf to Raf | Yes | Yes | Yes | root/6LN | 720 | ~Raf to ~Raf | Yes | Yes | Yes | root/6LR | 721 +--------------+------+------+-----------+---------------+ 723 Table 2: Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP 724 encapsulation 726 6.1. Example of Flow from RPL-aware-leaf to root 728 In non-storing mode the leaf node uses default routing to send 729 traffic to the root. The RPI header must be included to avoid/detect 730 loops. 732 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 734 This situation is the same case as storing mode. 736 +-------------------+-----+-----+------+ 737 | Header | 6LN | 6LR | 6LBR | 738 +-------------------+-----+-----+------+ 739 | Inserted headers | RPI | -- | -- | 740 | Removed headers | -- | -- | RPI | 741 | Re-added headers | -- | -- | RPI | 742 | Modified headers | -- | -- | -- | 743 | Untouched headers | -- | -- | -- | 744 +-------------------+-----+-----+------+ 746 Non Storing: Summary of the use of headers from RPL-aware-leaf to 747 root 749 6.2. Example of Flow from root to RPL-aware-leaf 751 In this case the flow comprises: 753 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 754 The 6LBR will insert an RH3, and may optionally insert an RPI header. 755 No IP-in-IP header is necessary as the traffic originates with an RPL 756 aware node. 758 +-------------------+-----------------+------+----------+ 759 | Header | 6LBR | 6LR | 6LN | 760 +-------------------+-----------------+------+----------+ 761 | Inserted headers | (opt: RPI), RH3 | -- | -- | 762 | Removed headers | -- | -- | RH3,RPI | 763 | Re-added headers | -- | -- | -- | 764 | Modified headers | -- | RH3 | -- | 765 | Untouched headers | -- | -- | -- | 766 +-------------------+-----------------+------+----------+ 768 Non Storing: Summary of the use of headers from root to RPL-aware- 769 leaf 771 6.3. Example of Flow from root to not-RPL-aware-leaf 773 In this case the flow comprises: 775 root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node) 777 In 6LBR the RH3 is added, and modified in 6LR where it is fully 778 consumed, but left there. If the RPI is left present, the IPv6 node 779 which does not understand it will drop it, therefore the RPI should 780 be removed before reaching the IPv6-only node. To permit removal, an 781 IP-in-IP header (hop-by-hop) or addressed to the last 6LR is 782 necessary. Due the complete knowledge of the topology at the root, 783 the 6LBR is able to address the IP-in-IP header to the last 6LR. 785 Omitting the RPI entirely is therefore a better solution, as no IP- 786 in-IP header is necessary. 788 +-------------------+------+-----+------+ 789 | Header | 6LBR | 6LR | IPv6 | 790 +-------------------+------+-----+------+ 791 | Inserted headers | RH3 | -- | -- | 792 | Removed headers | -- | -- | -- | 793 | Re-added headers | -- | -- | -- | 794 | Modified headers | -- | RH3 | -- | 795 | Untouched headers | -- | -- | -- | 796 +-------------------+------+-----+------+ 798 Non Storing: Summary of the use of headers from root to not-RPL- 799 aware-leaf 801 6.4. Example of Flow from not-RPL-aware-leaf to root 803 In this case the flow comprises: 805 IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR) 807 In this case the RPI is added by the first 6LR, encapsulated in an 808 IP-in-IP header, and is not modified in the followings 6LRs. The RPI 809 and entire packet is consumed by the root. 811 +-------------------+------+----------------+------+----------------+ 812 | Header | IPv6 | 6LR1 | 6LR2 | 6LBR | 813 +-------------------+------+----------------+------+----------------+ 814 | Inserted headers | -- | IP-in-IP(RPI) | -- | -- | 815 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 816 | Re-added headers | -- | -- | -- | -- | 817 | Modified headers | -- | -- | -- | -- | 818 | Untouched headers | -- | IP-in-IP(RPI) | -- | -- | 819 +-------------------+------+----------------+------+----------------+ 821 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 822 root 824 6.5. Example of Flow from RPL-aware-leaf to Internet 826 In this case the flow comprises: 828 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 830 This case requires that the RPI be added, but remoted by the 6LBR. 831 The 6LN must therefore add the RPI inside an IP-in-IP header, 832 addressed to the root. This case is identical to storing-mode case. 834 The IPv6 flow label should be set to zero to aid in compression, and 835 the 6LBR will set it to a non-zero value when sending towards the 836 Internet. 838 +-----------------+---------------+------+---------------+----------+ 839 | Header | 6LN | 6LR | 6LBR | Internet | 840 +-----------------+---------------+------+---------------+----------+ 841 | Inserted | IP-in-IP(RPI) | -- | -- | -- | 842 | headers | | | | | 843 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 844 | Re-added | -- | -- | -- | -- | 845 | headers | | | | | 846 | Modified | -- | -- | -- | -- | 847 | headers | | | | | 848 | Untouched | -- | RPI | -- | -- | 849 | headers | | | | | 850 +-----------------+---------------+------+---------------+----------+ 852 Non Storing: Summary of the use of headers from RPL-aware-leaf to 853 Internet 855 6.6. Example of Flow from Internet to RPL-aware-leaf 857 In this case the flow comprises: 859 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 861 The 6LBR must add an RH3 header. As the 6LBR will know the path and 862 address of the target not, it can address the IP-in-IP header to that 863 node. The 6LBR will zero the flow label upon entry in order to aid 864 compression. 866 The RPI may be added or not. 868 +----------+----------+-----------------------+---------------+-----+ 869 | Header | Internet | 6LBR | 6LR | 6LN | 870 +----------+----------+-----------------------+---------------+-----+ 871 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 872 | headers | | | | | 873 | Removed | -- | -- | IP-in-IP(RH3) | -- | 874 | headers | | | | | 875 | Re-added | -- | -- | -- | -- | 876 | headers | | | | | 877 | Modified | -- | -- | IP-in-IP(RH3) | -- | 878 | headers | | | | | 879 | Untouche | -- | -- | -- | -- | 880 | d | | | | | 881 | headers | | | | | 882 +----------+----------+-----------------------+---------------+-----+ 884 Non Storing: Summary of the use of headers from Internet to RPL- 885 aware-leaf 887 6.7. Example of Flow from not-RPL-aware-leaf to Internet 889 In this case the flow comprises: 891 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 893 In this case the flow label is recommended to be zero in the IPv6 894 node. As RPL headers are added in the IPv6 node, the first 6LN will 895 add an RPI header inside a new IP-in-IP header. The IP-in-IP header 896 will be addressed to the root. This case is identical to the 897 storing-mode case. 899 +-----------------+------+---------------+---------------+----------+ 900 | Header | IPv6 | 6LR | 6LBR | Internet | 901 +-----------------+------+---------------+---------------+----------+ 902 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 903 | headers | | | | | 904 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 905 | Re-added | -- | -- | -- | -- | 906 | headers | | | | | 907 | Modified | -- | -- | -- | -- | 908 | headers | | | | | 909 | Untouched | -- | -- | -- | -- | 910 | headers | | | | | 911 +-----------------+------+---------------+---------------+----------+ 913 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 914 Internet 916 6.8. Example of Flow from Internet to non-RPL-aware-leaf 918 In this case the flow comprises: 920 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) 922 The 6LBR must add an RH3 header inside an IP-in-IP header. The 6LBR 923 will know the path, and will recognize that the final node is not an 924 RPL capable node as it will have received the connectivity DAO from 925 the nearest 6LR. The 6LBR can therefore make the IP-in-IP header 926 destination be the last 6LR. The 6LBR will zero the flow label upon 927 entry in order to aid compression. 929 +----------+---------+-----------------------+---------------+------+ 930 | Header | Interne | 6LBR | 6LR | IPv6 | 931 | | t | | | | 932 +----------+---------+-----------------------+---------------+------+ 933 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 934 | headers | | | | | 935 | Removed | -- | -- | IP-in-IP(RH3, | -- | 936 | headers | | | RPI) | | 937 | Re-added | -- | -- | -- | -- | 938 | headers | | | | | 939 | Modified | -- | -- | -- | -- | 940 | headers | | | | | 941 | Untouche | -- | -- | -- | -- | 942 | d | | | | | 943 | headers | | | | | 944 +----------+---------+-----------------------+---------------+------+ 946 NonStoring: Summary of the use of headers from Internet to non-RPL- 947 aware-leaf 949 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 951 In this case the flow comprises: 953 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 955 This case involves only nodes in same RPL Domain. The originating 956 node will add an RPI header to the original packet, and send the 957 packet upwards. 959 The originating node could put the RPI into an IP-in-IP header 960 addressed to the root, so that the 6LBR can remove that header. 962 The 6LBR will need to insert an RH3 header, which requires that it 963 add an IP-in-IP header. It may be able to remove the RPI if it was 964 contained in an IP-in-IP header addressed to it. Otherwise, there 965 may be an RPI header buried inside the inner IP header, which should 966 get ignored. 968 Networks that use the RPL P2P extension [RFC6997] are essentially 969 non-storing DODAGs and fall into this scenario. 971 +----------+---------------+--------------+-----+-------------------+ 972 | Header | 6LN src | 6LBR | 6LR | 6LN dst | 973 +----------+---------------+--------------+-----+-------------------+ 974 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3 | -- | -- | 975 | headers | | to 6LN,RPI) | | | 976 | Removed | -- | -- | -- | IP-in-IP(RH3,RPI) | 977 | headers | | | | | 978 | Re-added | -- | -- | -- | -- | 979 | headers | | | | | 980 | Modified | -- | -- | -- | -- | 981 | headers | | | | | 982 | Untouche | -- | -- | -- | -- | 983 | d | | | | | 984 | headers | | | | | 985 +----------+---------------+--------------+-----+-------------------+ 987 Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 988 aware-leaf 990 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 992 In this case the flow comprises: 994 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LN 996 As in the previous case, the 6LN will insert an RPI header which MUST 997 be in an IP-in-IP header addressed to the root so that the 6LBR can 998 remove this RPI. The 6LBR will then insert an RH3 inside a new IP- 999 in-IP header addressed to the 6LN above the destination node. 1001 +-----------+---------------+---------------+----------------+------+ 1002 | Header | 6LN | 6LBR | 6LR | IPv6 | 1003 +-----------+---------------+---------------+----------------+------+ 1004 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- | 1005 | headers | | opt RPI) | | | 1006 | Removed | -- | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | 1007 | headers | | | opt RPI) | | 1008 | Re-added | -- | -- | -- | -- | 1009 | headers | | | | | 1010 | Modified | -- | -- | -- | -- | 1011 | headers | | | | | 1012 | Untouched | -- | -- | -- | -- | 1013 | headers | | | | | 1014 +-----------+---------------+---------------+----------------+------+ 1016 Non Storing: Summary of the use of headers from RPL-aware-leaf to 1017 not-RPL-aware-leaf 1019 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 1021 In this case the flow comprises: 1023 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 1025 This scenario is mostly identical to the previous one. The RPI is 1026 added by the first 6LR inside an IP-in-IP header addressed to the 1027 root. The 6LBR will remove this RPI, and add it's own IP-in-IP 1028 header containing an RH3 header. 1030 +------------+------+---------------+---------------+---------------+ 1031 | Header | IPv6 | 6LR | 6LBR | 6LN | 1032 +------------+------+---------------+---------------+---------------+ 1033 | Inserted | -- | IP-in-IP(RPI) | IP-in-IP(RH3) | -- | 1034 | headers | | | | | 1035 | Removed | -- | IP-in-IP(RPI) | -- | IP-in-IP(RH3) | 1036 | headers | | | | | 1037 | Re-added | -- | -- | -- | -- | 1038 | headers | | | | | 1039 | Modified | -- | -- | -- | -- | 1040 | headers | | | | | 1041 | Untouched | -- | -- | -- | -- | 1042 | headers | | | | | 1043 +------------+------+---------------+---------------+---------------+ 1045 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1046 RPL-aware-leaf 1048 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 1050 In this case the flow comprises: 1052 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 1053 6LN 1055 This scenario is the combination of the previous two cases. 1057 +----------+-----+-------------+--------------+--------------+------+ 1058 | Header | IPv | 6LR | 6LBR | 6LR | IPv6 | 1059 | | 6 | | | | | 1060 +----------+-----+-------------+--------------+--------------+------+ 1061 | Inserted | -- | IP-in- | IP-in- | -- | -- | 1062 | headers | | IP(RPI) | IP(RH3) | | | 1063 | Removed | -- | -- | IP-in- | IP-in- | -- | 1064 | headers | | | IP(RPI) | IP(RH3, opt | | 1065 | | | | | RPI) | | 1066 | Re-added | -- | -- | -- | -- | -- | 1067 | headers | | | | | | 1068 | Modified | -- | -- | -- | -- | -- | 1069 | headers | | | | | | 1070 | Untouche | -- | -- | -- | -- | -- | 1071 | d | | | | | | 1072 | headers | | | | | | 1073 +----------+-----+-------------+--------------+--------------+------+ 1075 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1076 not-RPL-aware-leaf 1078 7. Observations about the problem 1080 7.1. Storing mode 1082 In the completely general storing case, which includes not-RPL aware 1083 leaf nodes, it is not possible for a sending node to know if the 1084 destination is RPL aware, and therefore it must always use hop-by-hop 1085 IP-in-IP encapsulation, and it can never omit the IP-in-IP 1086 encapsulation. See table Table 1 1088 The simplest fully general stiaution for storing mode is to always 1089 put in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch] 1090 shows that this hop-by-hop IP-in-IP header can be compressed down to 1091 {TBD} bytes. 1093 There are potential significant advantages to having a single code 1094 path that always processes IP-in-IP headers with no options. 1096 If all RPL aware nodes can be told/configured that there are no non- 1097 RPL aware leaf nodes, then the only case where an IP-in-IP header is 1098 needed is when communicating outside the LLN. The 6LBR knows well 1099 when the communication is from the outside, and the 6LN can tell by 1100 comparing the destination address to the prefix provided in the PIO. 1101 If it is known that there are no communications outside the RPL 1102 domain (noting that the RPL domain may well extend to outside the 1103 LLN), then RPI headers can be included in all packets, and IP-in-IP 1104 headers are *never* needed. This may be significantly advantageous 1105 in relatively closed systems such as in building or industrial 1106 automation. Again, there are advantages to having a single code 1107 path. 1109 In order to support the above two cases with full generality, the 1110 different situations (always do IP-in-IP vs never use IP-in-IP) 1111 should be signaled in the RPL protocol itself. 1113 7.2. Non-Storing mode 1115 This the non-storing case, dealing with non-RPL aware leaf nodes is 1116 much easier as the 6LBR (DODAG root) has complete knowledge about the 1117 connectivity of all nodes, and all traffic flows through the root 1118 node. 1120 The 6LBR can recognize non-RPL aware leaf nodes because it will 1121 receive a DAO about that node from the 6LN immediately above that 1122 node. This means that the non-storing mode case can avoid ever using 1123 hop-by-hop IP-in-IP headers. 1125 It is unclear what it would mean for an RH3 header to be present in a 1126 hop-by-hop IP-in-IP header. The receiving node ought to consume the 1127 IP-in-IP header, and therefore consume the RH3 as well, and then 1128 attempt to send the packet again. But intermediate 6LN nodes would 1129 not know how to forward the packet, so the RH3 would need to be 1130 retained. This is a new kind of IPv6 packet processing. Therefore 1131 it may be that on the outbound leg of non-storing RPL networks, that 1132 hop-by-hop IP-in-IP header can NOT be used. 1134 [I-D.ietf-roll-routing-dispatch] shows how the destination=root, and 1135 destination=6LN IP-in-IP header can be compressed down to {TBD} 1136 bytes. 1138 Unlike in the storing mode case, there are no need for all nodes to 1139 know about the existence of non-RPL aware nodes. Only the 6LBR needs 1140 to change when there are non-RPL aware nodes. Further, in the non- 1141 storing case, the 6LBR is informed by the DAOs when there are non-RPL 1142 aware nodes. 1144 8. 6LoRH Compression cases 1146 The [I-D.ietf-roll-routing-dispatch] proposes a compression method 1147 for RPI, RH3 and IPv6-in-IPv6. 1149 In Storing Mode, for the examples of Flow from RPL-aware-leaf to non- 1150 RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise 1151 an IP-in-IP and RPI compression headers. The type of this case is 1152 critical since IP-in-IP is encapsulating a RPI header. 1154 +--+-----+---+--------------+-----------+-------------+-------------+ 1155 |1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC | 1156 +--+-----+---+--------------+-----------+-------------+-------------+ 1158 Figure 4: Critical IP-in-IP (RPI). 1160 9. IANA Considerations 1162 There are no IANA considerations related to this document. 1164 10. Security Considerations 1166 The security considerations covering of [RFC6553] and [RFC6554] apply 1167 when the packets get into RPL Domain. 1169 11. Acknowledgments 1171 This work is partially funded by the FP7 Marie Curie Initial Training 1172 Network (ITN) METRICS project (grant agreement No. 607728). 1174 The authors would like to acknowledge the review, feedback, and 1175 comments of Thomas Watteyne, Xavier Vilajosana, Robert Cragie, Simon 1176 Duquennoy and Peter van der Stok. 1178 12. References 1180 12.1. Normative References 1182 [I-D.ietf-6man-rfc2460bis] 1183 Deering, D. and R. Hinden, "Internet Protocol, Version 6 1184 (IPv6) Specification", draft-ietf-6man-rfc2460bis-05 (work 1185 in progress), June 2016. 1187 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1188 Requirement Levels", BCP 14, RFC 2119, 1189 DOI 10.17487/RFC2119, March 1997, 1190 . 1192 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1193 (IPv6) Specification", RFC 2460, December 1998. 1195 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1196 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1197 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1198 Low-Power and Lossy Networks", RFC 6550, 1199 DOI 10.17487/RFC6550, March 2012, 1200 . 1202 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 1203 Power and Lossy Networks (RPL) Option for Carrying RPL 1204 Information in Data-Plane Datagrams", RFC 6553, 1205 DOI 10.17487/RFC6553, March 2012, 1206 . 1208 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 1209 Routing Header for Source Routes with the Routing Protocol 1210 for Low-Power and Lossy Networks (RPL)", RFC 6554, 1211 DOI 10.17487/RFC6554, March 2012, 1212 . 1214 12.2. Informative References 1216 [I-D.ietf-6tisch-architecture] 1217 Thubert, P., "An Architecture for IPv6 over the TSCH mode 1218 of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work 1219 in progress), June 2016. 1221 [I-D.ietf-roll-routing-dispatch] 1222 Thubert, P., Bormann, C., Toutain, L., and R. Cragie, 1223 "6LoWPAN Routing Header", draft-ietf-roll-routing- 1224 dispatch-00 (work in progress), March 2016. 1226 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1227 Control Message Protocol (ICMPv6) for the Internet 1228 Protocol Version 6 (IPv6) Specification", RFC 4443, 1229 DOI 10.17487/RFC4443, March 2006, 1230 . 1232 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1233 Bormann, "Neighbor Discovery Optimization for IPv6 over 1234 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1235 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1236 . 1238 [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and 1239 J. Martocci, "Reactive Discovery of Point-to-Point Routes 1240 in Low-Power and Lossy Networks", RFC 6997, 1241 DOI 10.17487/RFC6997, August 2013, 1242 . 1244 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 1245 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 1246 2014, . 1248 [Second6TischPlugtest] 1249 "2nd 6Tisch Plugtest", . 1252 Authors' Addresses 1254 Maria Ines Robles 1255 Ericsson 1256 Hirsalantie 11 1257 Jorvas 02420 1258 Finland 1260 Email: maria.ines.robles@ericsson.com 1262 Michael C. Richardson 1263 Sandelman Software Works 1264 470 Dawson Avenue 1265 Ottawa, ON K1Z 5V7 1266 CA 1268 Email: mcr+ietf@sandelman.ca 1269 URI: http://www.sandelman.ca/ 1271 Pascal Thubert 1272 Cisco Systems, Inc 1273 Village d'Entreprises Green Side 400, Avenue de Roumanille 1274 Batiment T3, Biot - Sophia Antipolis 06410 1275 France 1277 Email: pthubert@cisco.com