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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'TO DO' is mentioned on line 305, but not defined ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: draft-ietf-6man-rfc2460bis has been published as RFC 8200 == Outdated reference: draft-ietf-6tisch-architecture has been published as RFC 9030 == Outdated reference: draft-ietf-roll-routing-dispatch has been published as RFC 8138 Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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: December 12, 2016 SSW 6 P. Thubert 7 Cisco 8 June 10, 2016 10 When to use RFC 6553, 6554 and IPv6-in-IPv6 11 draft-ietf-roll-useofrplinfo-05 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 December 12, 2016. 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 . . . . . 11 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 . . . . . 12 66 5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 13 67 5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 13 68 5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 14 69 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 15 70 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 16 71 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 17 72 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 73 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 18 74 6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 19 75 6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 19 76 6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 20 77 6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 20 78 6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 21 79 6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 22 80 6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 22 81 6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 23 82 6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 24 83 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 24 84 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 25 85 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 26 86 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware- 87 leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 27 88 7. Observations about the problem . . . . . . . . . . . . . . . 27 89 7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 27 90 7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 28 91 8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 29 92 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 93 10. Security Considerations . . . . . . . . . . . . . . . . . . . 29 94 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 95 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 96 12.1. Normative References . . . . . . . . . . . . . . . . . . 29 97 12.2. Informative References . . . . . . . . . . . . . . . . . 30 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 100 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. Internet is connected through the 6BBR. For the 236 following uses cases the 6BBR would be mapped to 6LBR and the 237 Backbone router to 6LR. 239 +---------+ 240 +---+Internet | 241 | +---------+ 242 | 243 | 244 +-----+ 245 | | Border Router to the RPL domain 246 | | (may be a RPL virtual root) 247 +-----+ 248 | 249 | Backbone 250 +-------------------+-------------------+ 251 | | | 252 +-----+ +-----+ +-----+ 253 | | Backbone | | Backbone | | Backbone 254 | | router | | router | | router 255 +|---|+ +-|||-+ +-[_]-+ 256 | | PCI-exp / | \ USB | Ethernet 257 ( ) ( ) ( )( )( ) (6LBR == RPL DODAG root) 258 o o o o o o o o o o o o 259 o o o o o o o o o o o o o o o o 260 o o o o o o o o o o 6LR == RPL router) o o 261 o o o o o o o z 262 o o o o o o (6LoWPAN Host) 264 <----------------------- RPL Instances ------------------------> 266 Figure 3: RPL domain architecture 268 4. Use cases 270 In data plane context a combination of RFC6553, RFC6554 and IPv6-in- 271 IPv6 encapsulation is going to be analyzed for the following traffic 272 flows: 274 RPL-aware-leaf to root 275 root to RPL-aware-leaf 277 not-RPL-aware-leaf to root 279 root to not-RPL-aware-leaf 281 RPL-aware-leaf to Internet 283 Internet to RPL-aware-leaf 285 not-RPL-aware-leaf to Internet 287 Internet to not-RPL-aware-leaf 289 RPL-aware-leaf to RPL-aware-leaf 291 RPL-aware-leaf to not-RPL-aware-leaf 293 not-RPL-aware-leaf to RPL-aware-leaf 295 not-RPL-aware-leaf to not-RPL-aware-leaf 297 This document assumes a rule that a Header cannot be inserted or 298 removed on the fly inside an IPv6 packet that is being routed. This 299 is a fundamental precept of the IPv6 architecture as outlined in 300 [RFC2460] is that Extensions may not be added or removed except by 301 the sender or the receiver. 303 Note: current discussions on [I-D.ietf-6man-rfc2460bis] related to 304 extensions headers may affect some cases in this document (Ticket 305 nro. 9) in 6man. [TO DO]. 307 A second important thing is that packets with a Hop-by-Hop option 308 which are marked with option type 01 ([RFC2460] section 4.2) must be 309 discarded if received by a host or router which does not understand 310 that option. This means that in general, any packet that leaves the 311 RPL domain of an LLN (or leaves the LLN entirely) is likely to be 312 discarded if it still contains an [RFC6553] RPL Option Header known 313 as the RPI. 315 The combination of these two rules means that the arrangement of 316 headers must be done so that traffic intended to exit the RPL domain 317 can have the RPI option removed prior to leaving the RPL domain. 319 An intermediate router that needs to add a header must encapsulate 320 the packet in an (additional) outer IP header where the new header 321 can be placed. 323 This also means that a Header can only be removed by an intermediate 324 router if it is placed in an encapsulating IPv6 Header, and in that 325 case, the whole encapsulating header must be removed - a replacement 326 may be added. Further, an intermediate router can only remove such 327 an outer header if that outer header has the router as the 328 destination! 330 Both RPI and RH3 headers may be modified by routers on the path of 331 the packet without the need to add to remove an encapsulating header. 332 Both headers were designed with this modification in mind, and both 333 the RPL RH and the RPL option are marked mutable but recoverable, so 334 an IPsec AH security header can be applied across these headers, but 335 it may not secure all the values in those headers. 337 RPI should be present in every single RPL data packet. There is one 338 exception in non-storing mode: when a packet is going down from the 339 root. In a downward non-storing mode, the entire route is written, 340 so there can be no loops by construction, nor any confusion about 341 which forwarding table to use. There may be cases (such as in 342 6tisch) where the instanceID may still be needed to pick an 343 appropriate priority or channel at each hop. 345 The applicability for storing (RPL-SM) and non-Storing (RPL-NSM) 346 modes for the previous cases is showed as follows: 348 In tables, the term "RPL aware leaf" is has been shortened to "Raf", 349 and "not-RPL aware leaf" has been shortened to "~Raf" to make the 350 table fit in available space. 352 The earlier examples are more complete to make sure that the process 353 is clear, while later examples are more consise. 355 5. Storing mode 357 In storing mode (fully stateful), determinate whether the destination 358 is RPL capable is not currently discernible by the sender and thus 359 would need an IP-in-IP header. The IP-in-IP header needs to be 360 addressed on a hop-by-hop basis so that the last 6LR can remove the 361 RPI header. Additionally, The sender can determine if the 362 destination is inside the LLN by looking if the destination address 363 is matched by the DIO's PIO option. 365 The following table summarizes what headers are needed in the 366 following scenarios, and indicates the IP-in-IP header must be 367 inserted on a hop-by-hop basis, and when it can target the 368 destination node directly. There are three possible situations: hop- 369 by-hop necessary (indicated by "hop"), or destination address 370 possible (indicated by "dst"). In all cases hop by hop can be used. 372 In cases where no IP-in-IP header is needed, the column is left 373 blank. 375 The leaf can be a router 6LR or a host, both indicated as 6LN. 377 +--------------+-------+-------+-----------+---------------+ 378 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 379 +--------------+-------+-------+-----------+---------------+ 380 | Raf to root | Yes | No | No | -- | 381 | root to Raf | Yes | No | No | -- | 382 | root to ~Raf | Yes | No | Yes | hop | 383 | ~Raf to root | Yes | No | Yes | root | 384 | Raf to Int | Yes | No | Yes | root | 385 | Int to Raf | Yes | No | Yes | raf | 386 | ~Raf to Int | Yes | No | Yes | root | 387 | Int to ~Raf | Yes | No | Yes | hop | 388 | Raf to Raf | Yes | No | No | -- | 389 | Raf to ~Raf | Yes | No | Yes | hop | 390 | ~Raf to Raf | Yes | No | Yes | dst | 391 | ~Raf to ~Raf | Yes | No | Yes | hop | 392 +--------------+-------+-------+-----------+---------------+ 394 Table 1: Headers needed in Storing mode: RPI, RH3, IP-in-IP 395 encapsulation 397 5.1. Example of Flow from RPL-aware-leaf to root 399 In storing mode, RFC 6553 (RPI) is used to send RPL Information 400 instanceID and rank information. 402 As stated in Section 16.2 of [RFC6550] a RPL-aware-leaf node does 403 not generally issue DIO messages; a leaf node accepts DIO messages 404 from upstream. (When the inconsistency in routing occurs, a leaf 405 node will generate a DIO with an infinite rank, to fix it). It may 406 issue DAO and DIS messages though it generally ignores DAO and DIS 407 messages. 409 In storing mode, RFC 6553 (RPI) is used to send RPL Information 410 instanceID and rank information. 412 In this case the flow comprises: 414 RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR) 416 As it was mentioned In this document 6LRs, 6LBR are always full- 417 fledge RPL routers, and are the RPL root node. 419 The 6LN inserts the RPI header, and sends the packet to 6LR which 420 decrements the rank in RPI and sends the packet up. When the packet 421 arrives at 6LBR, the RPI is removed and the packet is processed. 423 The RPI header can be removed by the 6LBR because the packet is 424 addressed to the 6LBR. The 6LN must know that it is communicating 425 with the 6LBR in order to be able to make use of this scenario. The 426 6LN can know the address of the 6LBR because it knows the address of 427 the root via the DODAGID in the DIO messages. 429 +-------------------+-----+------+------+ 430 | Header | 6LN | 6LR | 6LBR | 431 +-------------------+-----+------+------+ 432 | Inserted headers | RPI | -- | -- | 433 | Removed headers | -- | -- | RPI | 434 | Re-added headers | -- | -- | -- | 435 | Modified headers | -- | RPI | -- | 436 | Untouched headers | -- | -- | -- | 437 +-------------------+-----+------+------+ 439 Storing: Summary of the use of headers from RPL-aware-leaf to root 441 5.2. Example of Flow from root to RPL-aware-leaf 443 In this case the flow comprises: 445 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 447 In this case the 6LBR insert RPI header and send the packet down, the 448 6LR is going to increment the rank in RPI (examines instanceID for 449 multiple tables), the packet is processed in 6LN and RPI removed. 451 No IP-in-IP header is required. 453 +-------------------+------+-------+------+ 454 | Header | 6LBR | 6LR | 6LN | 455 +-------------------+------+-------+------+ 456 | Inserted headers | RPI | -- | -- | 457 | Removed headers | -- | -- | RPI | 458 | Re-added headers | -- | -- | -- | 459 | Modified headers | -- | RPI | -- | 460 | Untouched headers | -- | -- | -- | 461 +-------------------+------+-------+------+ 463 Storing: Summary of the use of headers from root to RPL-aware-leaf 465 5.3. Example of Flow from root to not-RPL-aware-leaf 467 In this case the flow comprises: 469 root (6LBR)--> 6LR --> not-RPL-aware-leaf (6LN) 471 The question in this scenario is how the root knows how to address 472 the IPv6-in-IPv6 header. It can not know that the destination isn't 473 RPL aware, so it must insert an IPv6 header that can be removed on 474 the last RPL aware node. Since the root can not know in a storing 475 network where the last RPL aware node is, the IPv6-in-IPv6 header 476 must be added hop-by-hop along the path from root to leaf. 478 The root (6LBR) uses IPv6-in-IPv6 encapsulation to transmit 479 information not related with the RPL domain. In the 6LBR the RPI 480 header is inserted into an IPv6-in-IPv6 header addressed to the last 481 6LR, which removes the header before it passes the packet to the IPv6 482 node (6LN). 484 An alternative option is to add an attribute in the RPL Target Option 485 to indicate that the target is not RPL aware: future work may explore 486 this possibility. 488 +-------------------+---------------+---------------+------+ 489 | Header | 6LBR | 6LR | IPv6 | 490 +-------------------+---------------+---------------+------+ 491 | Inserted headers | IP-in-IP(RPI) | -- | -- | 492 | Removed headers | -- | IP-in-IP(RPI) | -- | 493 | Re-added headers | -- | -- | -- | 494 | Modified headers | -- | -- | -- | 495 | Untouched headers | -- | -- | -- | 496 +-------------------+---------------+---------------+------+ 498 Storing: Summary of the use of headers from root to not-RPL-aware- 499 leaf 501 5.4. Example of Flow from not-RPL-aware-leaf to root 503 In this case the flow comprises: 505 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 507 When the packet arrives from IPv6 node to 6LR, the 6LR will insert an 508 RPI header, encapsuladed in a IPv6-in-IPv6 header. The IPv6-in-IPv6 509 header can be addressed to the next hop, or to the root. The root 510 removes the header and processes the packet. 512 +-------------------+------+----------------+---------------+ 513 | Header | IPv6 | 6LR | 6LBR | 514 +-------------------+------+----------------+---------------+ 515 | Inserted headers | -- | IP-in-IP(RPI) | -- | 516 | Removed headers | -- | -- | IP-in-IP(RPI) | 517 | Re-added headers | -- | -- | -- | 518 | Modified headers | -- | -- | -- | 519 | Untouched headers | -- | -- | -- | 520 +-------------------+------+----------------+---------------+ 522 Storing: Summary of the use of headers from not-RPL-aware-leaf to 523 root 525 5.5. Example of Flow from RPL-aware-leaf to Internet 527 RPL information from RFC 6553 should not go out to Internet as it 528 will cause the packet to be discarded at the first non-RPI aware 529 router. The 6LBR must be able to take this information out before 530 sending the packet upwards to the Internet. This requires the RPI 531 header be placed in an IP-in-IP header that the root can remove. 533 In this case the flow comprises: 535 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 537 The 6LN will insert the RPI in a IPv6-in-IPv6 in a outer header, 538 which may be addressed to the 6LBR (root), or alternatively, it could 539 be addressed hop-by-hop. 541 +-----------------+---------------+------+---------------+----------+ 542 | Header | 6LN | 6LR | 6LBR | Internet | 543 +-----------------+---------------+------+---------------+----------+ 544 | Inserted | IP-in-IP(RPI) | -- | -- | -- | 545 | headers | | | | | 546 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 547 | Re-added | -- | -- | -- | -- | 548 | headers | | | | | 549 | Modified | -- | RPI | -- | -- | 550 | headers | | | | | 551 | Untouched | -- | -- | -- | -- | 552 | headers | | | | | 553 +-----------------+---------------+------+---------------+----------+ 555 Storing: Summary of the use of headers from RPL-aware-leaf to 556 Internet 558 5.6. Example of Flow from Internet to RPL-aware-leaf 560 In this case the flow comprises: 562 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 564 When the packet arrives from Internet to 6LBR the RPI header is added 565 in a outer IPv6-in-IPv6 header and sent to 6LR, which modifies the 566 rank in the RPI. When the packet arrives at 6LN the RPI header is 567 removed and the packet processed. 569 +-----------------+----------+---------------+------+---------------+ 570 | Header | Internet | 6LBR | 6LR | 6LN | 571 +-----------------+----------+---------------+------+---------------+ 572 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 573 | headers | | | | | 574 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 575 | Re-added | -- | -- | -- | -- | 576 | headers | | | | | 577 | Modified | -- | -- | RPI | -- | 578 | headers | | | | | 579 | Untouched | -- | -- | -- | -- | 580 | headers | | | | | 581 +-----------------+----------+---------------+------+---------------+ 583 Storing: Summary of the use of headers from Internet to RPL-aware- 584 leaf 586 5.7. Example of Flow from not-RPL-aware-leaf to Internet 588 In this case the flow comprises: 590 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 592 The 6LR node will add an IP-in-IP(RPI) header addressed either to the 593 root, or hop-by-hop such that the root can remove the RPI header 594 before passing upwards. 596 The originating node will ideally leave the IPv6 flow label as zero 597 so that it can be better compressed through the LLN, and the 6LBR 598 will set the flow label to a non-zero value when sending to the 599 Internet. 601 +-----------------+------+---------------+---------------+----------+ 602 | Header | 6LN | 6LR | 6LBR | Internet | 603 +-----------------+------+---------------+---------------+----------+ 604 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 605 | headers | | | | | 606 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 607 | Re-added | -- | -- | -- | -- | 608 | headers | | | | | 609 | Modified | -- | -- | -- | -- | 610 | headers | | | | | 611 | Untouched | -- | -- | -- | -- | 612 | headers | | | | | 613 +-----------------+------+---------------+---------------+----------+ 615 Storing: Summary of the use of headers from not-RPL-aware-leaf to 616 Internet 618 5.8. Example of Flow from Internet to non-RPL-aware-leaf 620 In this case the flow comprises: 622 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) 624 The 6LBR will have to add an RPI header within an IP-in-IP header. 625 The IP-in-IP will need to be addressed hop-by-hop along the path as 626 in storing mode, the 6LBR has no idea if the 6LN is RPL aware or not, 627 nor what the closest attached 6LR node is. 629 The 6LBR MAY set the flow label on the inner IP-in-IP header to zero 630 in order to aid in compression, as the packet will not emerge again 631 from the LLN. 633 +-----------------+----------+---------------+---------------+------+ 634 | Header | Internet | 6LBR | 6LR | IPv6 | 635 +-----------------+----------+---------------+---------------+------+ 636 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 637 | headers | | | | | 638 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 639 | Re-added | -- | -- | -- | -- | 640 | headers | | | | | 641 | Modified | -- | -- | -- | -- | 642 | headers | | | | | 643 | Untouched | -- | -- | -- | -- | 644 | headers | | | | | 645 +-----------------+----------+---------------+---------------+------+ 647 Storing: Summary of the use of headers from Internet to non-RPL- 648 aware-leaf 650 5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 652 In [RFC6550] RPL allows a simple one-hop optimization for both 653 storing and non-storing networks. A node may send a packet destined 654 to a one-hop neighbor directly to that node. Section 9 in [RFC6550]. 656 In this case the flow comprises: 658 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 660 This case is assumed in the same RPL Domain. In the common parent, 661 the direction of RPI is changed (from increasing to decreasing the 662 rank). 664 While the 6LR nodes will update the RPI, no node needs to add or 665 remove the RPI, so no IP-in-IP headers are necessary. The ability to 666 do this depends upon the sending know that the destination is: a) 667 inside the LLN, and b) RPL capable. 669 The sender can determine if the destination is inside the LLN by 670 looking if the destination address is matched by the DIO's PIO 671 option. This check may be modified by the use of backbone routers, 672 but in this case it is assumed that the backbone routers are RPL 673 capable and so can process the RPI header correctly. 675 The other check, that the destination is RPL capable is not currently 676 discernible by the sender. This information is necessary to 677 distinguish this test case from Section 5.10. 679 +-------------+-------+---------------+---------------+-----+-------+ 680 | Header | 6LN | 6LR | 6LR (common | 6LR | 6LN | 681 | | src | | parent) | | dst | 682 +-------------+-------+---------------+---------------+-----+-------+ 683 | Inserted | RPI | -- | -- | -- | -- | 684 | headers | | | | | | 685 | Removed | -- | -- | -- | -- | RPI | 686 | headers | | | | | | 687 | Re-added | -- | -- | -- | -- | -- | 688 | headers | | | | | | 689 | Modified | -- | RPI | RPI | -- | -- | 690 | headers | | (decreasing | (increasing | | | 691 | | | rank) | rank) | | | 692 | Untouched | -- | -- | -- | -- | -- | 693 | headers | | | | | | 694 +-------------+-------+---------------+---------------+-----+-------+ 696 Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 697 aware-leaf 699 5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 701 In this case the flow comprises: 703 6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN 705 The sender, being aware out of band, that the receiver is not RPL 706 aware, sends adds an RPI header inside an IP-in-IP header. The IP- 707 in-IP header needs to be addressed on a hop-by-hop basis so that the 708 last 6LR can remove the RPI header. 710 ,---. 711 / \ 712 ( 6LR2 ) IP3,RPI,IP,ULP 713 ,-" . 714 ,-" `---' `. 715 ,' `. 716 ,---. ,-" `,---. 717 / +" / \ 718 ( 6LR1 ) Remove the IP3,RPI( 6LR3 ) 719 \ / \ / 720 /---' `---'| 721 / IP2,RPI,IP,ULP \ 722 / | 723 / \ 724 ,---+-. | 725 / \ +--+----+ 726 ( 6LN ) | | 727 \ / | IPv6 | IP,ULP 728 `-----' | | 729 IP1,RPI,IP,ULP +-------+ 731 Figure 4: Solution IPv6-in-IPv6 in each hop 733 Alternatively, if the definition of the Option Type field of RPL 734 Option '01' were changed so that it isn't a "discard if not 735 recognized", then no IP-in-IP header would be necessary. This change 736 is an incompatible on-the-wire change and would require some kind of 737 flag day, possibly a change that is done simultaenously with an 738 updated 6LoRH compress. 740 +--------+------------+------------+------------+------------+------+ 741 | Header | 6LN | 6LR | 6LR | 6LR | IPv6 | 742 | | | | (common | | | 743 | | | | parent) | | | 744 +--------+------------+------------+------------+------------+------+ 745 | Insert | IP-in- | -- | -- | -- | -- | 746 | ed hea | IP(RPI) | | | | | 747 | ders | | | | | | 748 | Remove | -- | -- | -- | IP-in- | -- | 749 | d head | | | | IP(RPI) | | 750 | ers | | | | | | 751 | Re- | -- | -- | -- | -- | -- | 752 | added | | | | | | 753 | header | | | | | | 754 | s | | | | | | 755 | Modifi | -- | IP-in- | IP-in- | -- | -- | 756 | ed hea | | IP(RPI) | IP(RPI) | | | 757 | ders | | | | | | 758 | Untouc | -- | -- | -- | -- | -- | 759 | hed he | | | | | | 760 | aders | | | | | | 761 +--------+------------+------------+------------+------------+------+ 763 Storing: Summary of the use of headers from RPL-aware-leaf to not- 764 RPL-aware-leaf 766 5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 768 In this case the flow comprises: 770 not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN 772 The 6LR receives the packet from the the IPv6 node and inserts and 773 the RPI header encapsulated in IPv6-in-IPv6 header. The IP-in-IP 774 header could be addresses to the 6LN if the destination is known to 775 the RPL aware, otherwise must send the packet using a hop-by-hop IP- 776 in-IP header. Similar considerations apply from section 777 Section 5.10. 779 +--------+------+------------+------------+------------+------------+ 780 | Header | IPv6 | 6LR | common | 6LR | 6LN | 781 | | | | parent | | | 782 | | | | (6LR) | | | 783 +--------+------+------------+------------+------------+------------+ 784 | Insert | -- | IP-in- | -- | -- | -- | 785 | ed hea | | IP(RPI) | | | | 786 | ders | | | | | | 787 | Remove | -- | -- | -- | -- | IP-in- | 788 | d head | | | | | IP(RPI) | 789 | ers | | | | | | 790 | Re- | -- | -- | -- | -- | -- | 791 | added | | | | | | 792 | header | | | | | | 793 | s | | | | | | 794 | Modifi | -- | -- | IP-in- | IP-in- | -- | 795 | ed hea | | | IP(RPI) | IP(RPI) | | 796 | ders | | | | | | 797 | Untouc | -- | -- | -- | -- | -- | 798 | hed he | | | | | | 799 | aders | | | | | | 800 +--------+------+------------+------------+------------+------------+ 802 Storing: Summary of the use of headers from not-RPL-aware-leaf to 803 RPL-aware-leaf 805 5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 807 In this case the flow comprises: 809 not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not- 810 RPL-aware 6LN (IPv6 node) 812 This flow combines the problems of the two previous sections. There 813 is no choice at the first 6LR: it must insert an RPI, and to do that 814 it must add an IP-in-IP header. That IP-in-IP header must be 815 addressed on a hop-by-hop basis. 817 +-----------+------+---------------+---------+---------------+------+ 818 | Header | IPv6 | 6LR | 6LR | 6LR | IPv6 | 819 | | src | | (common | | dst | 820 | | | | parent) | | | 821 +-----------+------+---------------+---------+---------------+------+ 822 | Inserted | -- | IP-in-IP(RPI) | -- | -- | -- | 823 | headers | | | | | | 824 | Removed | -- | -- | -- | IP-in-IP(RPI) | -- | 825 | headers | | | | | | 826 | Re-added | -- | -- | -- | -- | -- | 827 | headers | | | | | | 828 | Modified | -- | -- | -- | -- | -- | 829 | headers | | | | | | 830 | Untouched | -- | -- | -- | -- | -- | 831 | headers | | | | | | 832 +-----------+------+---------------+---------+---------------+------+ 834 Storing: Summary of the use of headers from not-RPL-aware-leaf to 835 not-RPL-aware-leaf 837 6. Non Storing mode 839 +--------------+------+------+-----------+---------------+ 840 | Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst | 841 +--------------+------+------+-----------+---------------+ 842 | Raf to root | Yes | No | No | -- | 843 | root to Raf | Yes | Yes | No | -- | 844 | root to ~Raf | No | Yes | Yes | 6LR | 845 | ~Raf to root | Yes | No | Yes | root | 846 | Raf to Int | Yes | No | Yes | root | 847 | Int to Raf | opt | Yes | Yes | dst | 848 | ~Raf to Int | Yes | No | Yes | root | 849 | Int to ~Raf | opt | Yes | Yes | 6LR | 850 | Raf to Raf | Yes | Yes | Yes | root/dst | 851 | Raf to ~Raf | Yes | Yes | Yes | root/6LR | 852 | ~Raf to Raf | Yes | Yes | Yes | root/6LN | 853 | ~Raf to ~Raf | Yes | Yes | Yes | root/6LR | 854 +--------------+------+------+-----------+---------------+ 856 Table 2: Headers needed in Non-Storing mode: RPI, RH3, IP-in-IP 857 encapsulation 859 6.1. Example of Flow from RPL-aware-leaf to root 861 In non-storing mode the leaf node uses default routing to send 862 traffic to the root. The RPI header must be included to avoid/detect 863 loops. 865 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) 867 This situation is the same case as storing mode. 869 +-------------------+-----+-----+------+ 870 | Header | 6LN | 6LR | 6LBR | 871 +-------------------+-----+-----+------+ 872 | Inserted headers | RPI | -- | -- | 873 | Removed headers | -- | -- | RPI | 874 | Re-added headers | -- | -- | RPI | 875 | Modified headers | -- | -- | -- | 876 | Untouched headers | -- | -- | -- | 877 +-------------------+-----+-----+------+ 879 Non Storing: Summary of the use of headers from RPL-aware-leaf to 880 root 882 6.2. Example of Flow from root to RPL-aware-leaf 884 In this case the flow comprises: 886 root (6LBR)--> 6LR --> RPL-aware-leaf (6LN) 888 The 6LBR will insert an RH3, and may optionally insert an RPI header. 889 No IP-in-IP header is necessary as the traffic originates with an RPL 890 aware node. 892 +-------------------+-----------------+------+----------+ 893 | Header | 6LBR | 6LR | 6LN | 894 +-------------------+-----------------+------+----------+ 895 | Inserted headers | (opt: RPI), RH3 | -- | -- | 896 | Removed headers | -- | -- | RH3,RPI | 897 | Re-added headers | -- | -- | -- | 898 | Modified headers | -- | RH3 | -- | 899 | Untouched headers | -- | -- | -- | 900 +-------------------+-----------------+------+----------+ 902 Non Storing: Summary of the use of headers from root to RPL-aware- 903 leaf 905 6.3. Example of Flow from root to not-RPL-aware-leaf 907 In this case the flow comprises: 909 root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node) 911 In 6LBR the RH3 is added, and modified in 6LR where it is fully 912 consumed, but left there. If the RPI is left present, the IPv6 node 913 which does not understand it will drop it, therefore the RPI should 914 be removed before reaching the IPv6-only node. To permit removal, an 915 IP-in-IP header (hop-by-hop) or addressed to the last 6LR is 916 necessary. Due the complete knowledge of the topology at the root, 917 the 6LBR is able to address the IP-in-IP header to the last 6LR. 919 Omitting the RPI entirely is therefore a better solution, as no IP- 920 in-IP header is necessary. 922 +-------------------+------+-----+------+ 923 | Header | 6LBR | 6LR | IPv6 | 924 +-------------------+------+-----+------+ 925 | Inserted headers | RH3 | -- | -- | 926 | Removed headers | -- | -- | -- | 927 | Re-added headers | -- | -- | -- | 928 | Modified headers | -- | RH3 | -- | 929 | Untouched headers | -- | -- | -- | 930 +-------------------+------+-----+------+ 932 Non Storing: Summary of the use of headers from root to not-RPL- 933 aware-leaf 935 6.4. Example of Flow from not-RPL-aware-leaf to root 937 In this case the flow comprises: 939 IPv6-node --> 6LR1 --> 6LR2 --> root (6LBR) 941 In this case the RPI is added by the first 6LR, encapsulated in an 942 IP-in-IP header, and is not modified in the followings 6LRs. The RPI 943 and entire packet is consumed by the root. 945 +-------------------+------+----------------+------+----------------+ 946 | Header | IPv6 | 6LR1 | 6LR2 | 6LBR | 947 +-------------------+------+----------------+------+----------------+ 948 | Inserted headers | -- | IP-in-IP(RPI) | -- | -- | 949 | Removed headers | -- | -- | -- | IP-in-IP(RPI) | 950 | Re-added headers | -- | -- | -- | -- | 951 | Modified headers | -- | -- | -- | -- | 952 | Untouched headers | -- | IP-in-IP(RPI) | -- | -- | 953 +-------------------+------+----------------+------+----------------+ 955 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 956 root 958 6.5. Example of Flow from RPL-aware-leaf to Internet 960 In this case the flow comprises: 962 RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 964 This case requires that the RPI be added, but remoted by the 6LBR. 965 The 6LN must therefore add the RPI inside an IP-in-IP header, 966 addressed to the root. This case is identical to storing-mode case. 968 The IPv6 flow label should be set to zero to aid in compression, and 969 the 6LBR will set it to a non-zero value when sending towards the 970 Internet. 972 +-----------------+---------------+------+---------------+----------+ 973 | Header | 6LN | 6LR | 6LBR | Internet | 974 +-----------------+---------------+------+---------------+----------+ 975 | Inserted | IP-in-IP(RPI) | -- | -- | -- | 976 | headers | | | | | 977 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 978 | Re-added | -- | -- | -- | -- | 979 | headers | | | | | 980 | Modified | -- | -- | -- | -- | 981 | headers | | | | | 982 | Untouched | -- | RPI | -- | -- | 983 | headers | | | | | 984 +-----------------+---------------+------+---------------+----------+ 986 Non Storing: Summary of the use of headers from RPL-aware-leaf to 987 Internet 989 6.6. Example of Flow from Internet to RPL-aware-leaf 991 In this case the flow comprises: 993 Internet --> root (6LBR) --> 6LR --> RPL-aware-leaf (6LN) 995 The 6LBR must add an RH3 header. As the 6LBR will know the path and 996 address of the target not, it can address the IP-in-IP header to that 997 node. The 6LBR will zero the flow label upon entry in order to aid 998 compression. 1000 The RPI may be added or not. 1002 +----------+----------+-----------------------+---------------+-----+ 1003 | Header | Internet | 6LBR | 6LR | 6LN | 1004 +----------+----------+-----------------------+---------------+-----+ 1005 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 1006 | headers | | | | | 1007 | Removed | -- | -- | IP-in-IP(RH3) | -- | 1008 | headers | | | | | 1009 | Re-added | -- | -- | -- | -- | 1010 | headers | | | | | 1011 | Modified | -- | -- | IP-in-IP(RH3) | -- | 1012 | headers | | | | | 1013 | Untouche | -- | -- | -- | -- | 1014 | d | | | | | 1015 | headers | | | | | 1016 +----------+----------+-----------------------+---------------+-----+ 1018 Non Storing: Summary of the use of headers from Internet to RPL- 1019 aware-leaf 1021 6.7. Example of Flow from not-RPL-aware-leaf to Internet 1023 In this case the flow comprises: 1025 not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet 1027 In this case the flow label is recommended to be zero in the IPv6 1028 node. As RPL headers are added in the IPv6 node, the first 6LN will 1029 add an RPI header inside a new IP-in-IP header. The IP-in-IP header 1030 will be addressed to the root. This case is identical to the 1031 storing-mode case. 1033 +-----------------+------+---------------+---------------+----------+ 1034 | Header | IPv6 | 6LR | 6LBR | Internet | 1035 +-----------------+------+---------------+---------------+----------+ 1036 | Inserted | -- | IP-in-IP(RPI) | -- | -- | 1037 | headers | | | | | 1038 | Removed headers | -- | -- | IP-in-IP(RPI) | -- | 1039 | Re-added | -- | -- | -- | -- | 1040 | headers | | | | | 1041 | Modified | -- | -- | -- | -- | 1042 | headers | | | | | 1043 | Untouched | -- | -- | -- | -- | 1044 | headers | | | | | 1045 +-----------------+------+---------------+---------------+----------+ 1047 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1048 Internet 1050 6.8. Example of Flow from Internet to non-RPL-aware-leaf 1052 In this case the flow comprises: 1054 Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN) 1056 The 6LBR must add an RH3 header inside an IP-in-IP header. The 6LBR 1057 will know the path, and will recognize that the final node is not an 1058 RPL capable node as it will have received the connectivity DAO from 1059 the nearest 6LR. The 6LBR can therefore make the IP-in-IP header 1060 destination be the last 6LR. The 6LBR will zero the flow label upon 1061 entry in order to aid compression. 1063 +----------+---------+-----------------------+---------------+------+ 1064 | Header | Interne | 6LBR | 6LR | IPv6 | 1065 | | t | | | | 1066 +----------+---------+-----------------------+---------------+------+ 1067 | Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- | 1068 | headers | | | | | 1069 | Removed | -- | -- | IP-in-IP(RH3, | -- | 1070 | headers | | | RPI) | | 1071 | Re-added | -- | -- | -- | -- | 1072 | headers | | | | | 1073 | Modified | -- | -- | -- | -- | 1074 | headers | | | | | 1075 | Untouche | -- | -- | -- | -- | 1076 | d | | | | | 1077 | headers | | | | | 1078 +----------+---------+-----------------------+---------------+------+ 1080 NonStoring: Summary of the use of headers from Internet to non-RPL- 1081 aware-leaf 1083 6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf 1085 In this case the flow comprises: 1087 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 1089 This case involves only nodes in same RPL Domain. The originating 1090 node will add an RPI header to the original packet, and send the 1091 packet upwards. 1093 The originating node could put the RPI into an IP-in-IP header 1094 addressed to the root, so that the 6LBR can remove that header. 1096 The 6LBR will need to insert an RH3 header, which requires that it 1097 add an IP-in-IP header. It may be able to remove the RPI if it was 1098 contained in an IP-in-IP header addressed to it. Otherwise, there 1099 may be an RPI header buried inside the inner IP header, which should 1100 get ignored. 1102 Networks that use the RPL P2P extension [RFC6997] are essentially 1103 non-storing DODAGs and fall into this scenario. 1105 +----------+---------------+--------------+-----+-------------------+ 1106 | Header | 6LN src | 6LBR | 6LR | 6LN dst | 1107 +----------+---------------+--------------+-----+-------------------+ 1108 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3 | -- | -- | 1109 | headers | | to 6LN,RPI) | | | 1110 | Removed | -- | -- | -- | IP-in-IP(RH3,RPI) | 1111 | headers | | | | | 1112 | Re-added | -- | -- | -- | -- | 1113 | headers | | | | | 1114 | Modified | -- | -- | -- | -- | 1115 | headers | | | | | 1116 | Untouche | -- | -- | -- | -- | 1117 | d | | | | | 1118 | headers | | | | | 1119 +----------+---------------+--------------+-----+-------------------+ 1121 Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL- 1122 aware-leaf 1124 6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 1126 In this case the flow comprises: 1128 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 6LN 1130 As in the previous case, the 6LN will insert an RPI header which MUST 1131 be in an IP-in-IP header addressed to the root so that the 6LBR can 1132 remove this RPI. The 6LBR will then insert an RH3 inside a new IP- 1133 in-IP header addressed to the 6LN above the destination node. 1135 +-----------+---------------+---------------+----------------+------+ 1136 | Header | 6LN | 6LBR | 6LR | IPv6 | 1137 +-----------+---------------+---------------+----------------+------+ 1138 | Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- | 1139 | headers | | opt RPI) | | | 1140 | Removed | -- | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | 1141 | headers | | | opt RPI) | | 1142 | Re-added | -- | -- | -- | -- | 1143 | headers | | | | | 1144 | Modified | -- | -- | -- | -- | 1145 | headers | | | | | 1146 | Untouched | -- | -- | -- | -- | 1147 | headers | | | | | 1148 +-----------+---------------+---------------+----------------+------+ 1150 Non Storing: Summary of the use of headers from RPL-aware-leaf to 1151 not-RPL-aware-leaf 1153 6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 1155 In this case the flow comprises: 1157 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> 6LN 1159 This scenario is mostly identical to the previous one. The RPI is 1160 added by the first 6LR inside an IP-in-IP header addressed to the 1161 root. The 6LBR will remove this RPI, and add it's own IP-in-IP 1162 header containing an RH3 header. 1164 +------------+------+---------------+---------------+---------------+ 1165 | Header | IPv6 | 6LR | 6LBR | 6LN | 1166 +------------+------+---------------+---------------+---------------+ 1167 | Inserted | -- | IP-in-IP(RPI) | IP-in-IP(RH3) | -- | 1168 | headers | | | | | 1169 | Removed | -- | IP-in-IP(RPI) | -- | IP-in-IP(RH3) | 1170 | headers | | | | | 1171 | Re-added | -- | -- | -- | -- | 1172 | headers | | | | | 1173 | Modified | -- | -- | -- | -- | 1174 | headers | | | | | 1175 | Untouched | -- | -- | -- | -- | 1176 | headers | | | | | 1177 +------------+------+---------------+---------------+---------------+ 1179 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1180 RPL-aware-leaf 1182 6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf 1184 In this case the flow comprises: 1186 not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware 1187 6LN 1189 This scenario is the combination of the previous two cases. 1191 +----------+-----+-------------+--------------+--------------+------+ 1192 | Header | IPv | 6LR | 6LBR | 6LR | IPv6 | 1193 | | 6 | | | | | 1194 +----------+-----+-------------+--------------+--------------+------+ 1195 | Inserted | -- | IP-in- | IP-in- | -- | -- | 1196 | headers | | IP(RPI) | IP(RH3) | | | 1197 | Removed | -- | -- | IP-in- | IP-in- | -- | 1198 | headers | | | IP(RPI) | IP(RH3, opt | | 1199 | | | | | RPI) | | 1200 | Re-added | -- | -- | -- | -- | -- | 1201 | headers | | | | | | 1202 | Modified | -- | -- | -- | -- | -- | 1203 | headers | | | | | | 1204 | Untouche | -- | -- | -- | -- | -- | 1205 | d | | | | | | 1206 | headers | | | | | | 1207 +----------+-----+-------------+--------------+--------------+------+ 1209 Non Storing: Summary of the use of headers from not-RPL-aware-leaf to 1210 not-RPL-aware-leaf 1212 7. Observations about the problem 1214 7.1. Storing mode 1216 In the completely general storing case, which includes not-RPL aware 1217 leaf nodes, it is not possible for a sending node to know if the 1218 destination is RPL aware, and therefore it must always use hop-by-hop 1219 IP-in-IP encapsulation, and it can never omit the IP-in-IP 1220 encapsulation. See table Table 1 1222 The simplest fully general stiaution for storing mode is to always 1223 put in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch] 1224 shows that this hop-by-hop IP-in-IP header can be compressed down to 1225 {TBD} bytes. 1227 There are potential significant advantages to having a single code 1228 path that always processes IP-in-IP headers with no options. 1230 If all RPL aware nodes can be told/configured that there are no non- 1231 RPL aware leaf nodes, then the only case where an IP-in-IP header is 1232 needed is when communicating outside the LLN. The 6LBR knows well 1233 when the communication is from the outside, and the 6LN can tell by 1234 comparing the destination address to the prefix provided in the PIO. 1235 If it is known that there are no communications outside the RPL 1236 domain (noting that the RPL domain may well extend to outside the 1237 LLN), then RPI headers can be included in all packets, and IP-in-IP 1238 headers are *never* needed. This may be significantly advantageous 1239 in relatively closed systems such as in building or industrial 1240 automation. Again, there are advantages to having a single code 1241 path. 1243 In order to support the above two cases with full generality, the 1244 different situations (always do IP-in-IP vs never use IP-in-IP) 1245 should be signaled in the RPL protocol itself. 1247 7.2. Non-Storing mode 1249 This the non-storing case, dealing with non-RPL aware leaf nodes is 1250 much easier as the 6LBR (DODAG root) has complete knowledge about the 1251 connectivity of all nodes, and all traffic flows through the root 1252 node. 1254 The 6LBR can recognize non-RPL aware leaf nodes because it will 1255 receive a DAO about that node from the 6LN immediately above that 1256 node. This means that the non-storing mode case can avoid ever using 1257 hop-by-hop IP-in-IP headers. 1259 It is unclear what it would mean for an RH3 header to be present in a 1260 hop-by-hop IP-in-IP header. The receiving node ought to consume the 1261 IP-in-IP header, and therefore consume the RH3 as well, and then 1262 attempt to send the packet again. But intermediate 6LN nodes would 1263 not know how to forward the packet, so the RH3 would need to be 1264 retained. This is a new kind of IPv6 packet processing. Therefore 1265 it may be that on the outbound leg of non-storing RPL networks, that 1266 hop-by-hop IP-in-IP header can NOT be used. 1268 [I-D.ietf-roll-routing-dispatch] shows how the destination=root, and 1269 destination=6LN IP-in-IP header can be compressed down to {TBD} 1270 bytes. 1272 Unlike in the storing mode case, there are no need for all nodes to 1273 know about the existence of non-RPL aware nodes. Only the 6LBR needs 1274 to change when there are non-RPL aware nodes. Further, in the non- 1275 storing case, the 6LBR is informed by the DAOs when there are non-RPL 1276 aware nodes. 1278 8. 6LoRH Compression cases 1280 The [I-D.ietf-roll-routing-dispatch] proposes a compression method 1281 for RPI, RH3 and IPv6-in-IPv6. 1283 In Storing Mode, for the examples of Flow from RPL-aware-leaf to non- 1284 RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise 1285 an IP-in-IP and RPI compression headers. The type of this case is 1286 critical since IP-in-IP is encapsulating a RPI header. 1288 +--+-----+---+--------------+-----------+-------------+-------------+ 1289 |1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC | 1290 +--+-----+---+--------------+-----------+-------------+-------------+ 1292 Figure 5: Critical IP-in-IP (RPI). 1294 9. IANA Considerations 1296 There are no IANA considerations related to this document. 1298 10. Security Considerations 1300 The security considerations covering of [RFC6553] and [RFC6554] apply 1301 when the packets get into RPL Domain. 1303 11. Acknowledgments 1305 This work is partially funded by the FP7 Marie Curie Initial Training 1306 Network (ITN) METRICS project (grant agreement No. 607728). 1308 The authors would like to acknowledge the review, feedback, and 1309 comments of Thomas Watteyne, Xavier Vilajosana, Robert Cragie, Simon 1310 Duquennoy and Peter van der Stok. 1312 12. References 1314 12.1. Normative References 1316 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1317 Requirement Levels", BCP 14, RFC 2119, 1318 DOI 10.17487/RFC2119, March 1997, 1319 . 1321 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1322 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 1323 December 1998, . 1325 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1326 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1327 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1328 Low-Power and Lossy Networks", RFC 6550, 1329 DOI 10.17487/RFC6550, March 2012, 1330 . 1332 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 1333 Power and Lossy Networks (RPL) Option for Carrying RPL 1334 Information in Data-Plane Datagrams", RFC 6553, 1335 DOI 10.17487/RFC6553, March 2012, 1336 . 1338 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 1339 Routing Header for Source Routes with the Routing Protocol 1340 for Low-Power and Lossy Networks (RPL)", RFC 6554, 1341 DOI 10.17487/RFC6554, March 2012, 1342 . 1344 12.2. Informative References 1346 [I-D.ietf-6man-rfc2460bis] 1347 Deering, S. and R. Hinden, "Internet Protocol, Version 6 1348 (IPv6) Specification", draft-ietf-6man-rfc2460bis-04 (work 1349 in progress), March 2016. 1351 [I-D.ietf-6tisch-architecture] 1352 Thubert, P., "An Architecture for IPv6 over the TSCH mode 1353 of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work 1354 in progress), June 2016. 1356 [I-D.ietf-roll-routing-dispatch] 1357 Thubert, P., Bormann, C., Toutain, L., and R. Cragie, 1358 "6LoWPAN Routing Header", draft-ietf-roll-routing- 1359 dispatch-00 (work in progress), March 2016. 1361 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1362 Control Message Protocol (ICMPv6) for the Internet 1363 Protocol Version 6 (IPv6) Specification", RFC 4443, 1364 DOI 10.17487/RFC4443, March 2006, 1365 . 1367 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1368 Bormann, "Neighbor Discovery Optimization for IPv6 over 1369 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1370 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1371 . 1373 [RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and 1374 J. Martocci, "Reactive Discovery of Point-to-Point Routes 1375 in Low-Power and Lossy Networks", RFC 6997, 1376 DOI 10.17487/RFC6997, August 2013, 1377 . 1379 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 1380 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 1381 2014, . 1383 [Second6TischPlugtest] 1384 "2nd 6Tisch Plugtest", . 1387 Authors' Addresses 1389 Maria Ines Robles 1390 Ericsson 1391 Hirsalantie 11 1392 Jorvas 02420 1393 Finland 1395 Email: maria.ines.robles@ericsson.com 1397 Michael C. Richardson 1398 Sandelman Software Works 1399 470 Dawson Avenue 1400 Ottawa, ON K1Z 5V7 1401 CA 1403 Email: mcr+ietf@sandelman.ca 1404 URI: http://www.sandelman.ca/ 1406 Pascal Thubert 1407 Cisco Systems, Inc 1408 Village d'Entreprises Green Side 400, Avenue de Roumanille 1409 Batiment T3, Biot - Sophia Antipolis 06410 1410 France 1412 Email: pthubert@cisco.com