idnits 2.17.1 draft-thubert-6lo-bier-dispatch-06.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 doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (January 28, 2019) is 1908 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'RFCthis' is mentioned on line 326, but not defined == Outdated reference: A later version (-30) exists of draft-ietf-6tisch-architecture-19 == Outdated reference: A later version (-13) exists of draft-ietf-detnet-architecture-10 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6lo P. Thubert, Ed. 3 Internet-Draft Cisco 4 Intended status: Standards Track Z. Brodard 5 Expires: August 1, 2019 Ecole Polytechnique 6 H. Jiang 7 G. Texier 8 Telecom Bretagne 9 January 28, 2019 11 A 6loRH for BitStrings 12 draft-thubert-6lo-bier-dispatch-06 14 Abstract 16 This specification extends the 6LoWPAN Routing Header to signal 17 BitStrings such as utilized in Bit Index Explicit Replication and its 18 Traffic Engineering variant. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on August 1, 2019. 37 Copyright Notice 39 Copyright (c) 2019 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 3 57 4. The BIER-6LoRH encoding . . . . . . . . . . . . . . . . . . . 4 58 4.1. The Bit-by-bit BitStrings . . . . . . . . . . . . . . . . 4 59 4.2. The Enumeration BitStrings . . . . . . . . . . . . . . . 5 60 4.3. Bloom Filters . . . . . . . . . . . . . . . . . . . . . . 5 61 4.4. Types of BIER-6LoRH header . . . . . . . . . . . . . . . 6 62 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 8 63 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 64 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 65 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 66 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 68 9.2. Informative References . . . . . . . . . . . . . . . . . 9 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 71 1. Introduction 73 The type of information that needs to be present in a packet inside 74 the LLN but not outside of the LLN varies with the routing operation, 75 but there is overall a need for an extensible compression technique 76 that would simplify the IP-in-IP encapsulation, when needed, and 77 optimally compress existing routing artifacts found in LLNs. 79 The 6LoWPAN Routing Header (6LoRH) [RFC8025] [RFC8138] is such a 80 technique, that extends the 6lo adaptation layer framework [RFC4944], 81 [RFC6282] so as to carry routing information for Route-over use 82 cases. The original specification includes the formats necessary for 83 RPL such as the Source Route Header (SRH) and is intended to be 84 extended for additional routing artifacts. 86 The Bit Index Explicit Replication (BIER), as introduced in the BIER 87 Architecture [RFC8279], can be used as an alternate artifact to route 88 multicast as well as unicast traffic. The Traffic Engineering for 89 Bit Index Explicit Replication [I-D.eckert-bier-te-arch] (BIER-TE) 90 adds support for traffic engineering by explicit hop-by-hop 91 forwarding and loose hop forwarding of packets along a unicast route. 93 This specification provides additional formats for the 6LoRH 94 compression to carry BitStrings such as used for Bit Index Explicit 95 Replication and its Traffic Engineering variant (BIER and BIER-TE, 96 respectively). 98 2. Terminology 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in 103 [RFC2119]. 105 The Terminology used in this document is consistent with and 106 incorporates that described in Terms Used in Routing for Low-Power 107 and Lossy Networks (LLNs). [RFC7102]. 109 Other terms in use in LLNs are found in Terminology for Constrained- 110 Node Networks [RFC7228]. 112 The term "byte" is used in its now customary sense as a synonym for 113 "octet". 115 "RPL", "RPL Packet Information" (RPI) and "RPL Instance" are defined 116 in the RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks 117 [RFC6550] specification. 119 The terms Bit-Forwarding Egress Routers (BFR), BFR-id and BitString 120 are defined in [RFC8279]. A BitString indicates a continuous 121 sequence of bits indexed by an offset in the sequence. The leftmost 122 bit is bit 0 and corresponds to the value 0x80 of the leftmost octet 123 in the BitString. 125 3. Applicability 127 BIER and other bit-indexed methods that would leverage BitStrings 128 will generally require additional information in the packet to 129 complement the BitString. For instance, BIER has the concept of a 130 BFR-id and an Entropy value in the BIER header. Since those 131 additional fields depend on the bit-indexed method, they are expected 132 to be transported separately from the BitString. This specification 133 concentrates on the BitString and a group identifier which enables a 134 network to grow beyond the size of one bitString. 136 Within the context of "the Deterministic Networking (DetNet) 137 Architecture" [I-D.ietf-detnet-architecture] ), the "BIER-TE-based 138 OAM, Replication and Elimination" 139 [I-D.thubert-bier-replication-elimination] document details how BIER- 140 TE can be leveraged to activate the Deterministic Networking 141 Replication and Elimination functions in a manner that is abstract to 142 the data plane forwarding information. An adjacency, which is 143 represented by a bit in the BIER header, can be mapped in the data 144 plane to an Ethernet hop, a Label Switched Path, or it may correspond 145 to a loose or a strict IPv6 Source Routed Path. 147 In the context of LLNs, the 6TiSCH Architecture 148 [I-D.ietf-6tisch-architecture] introduces the concept of a Track that 149 is a directional traffic-engineered path between a source and a 150 destination. A Track is indicated in a packet by a Source or 151 Destination IPv6 Address and a RPL Local Instance. The RPL Instance 152 is carried in an IPv6 packet as part of the RPL Packet Information 153 (RPI), and a bit in the RPI indicates whether the Instance is Local 154 to the Source or the Destination Address. The RPI can be compressed 155 as a RPI 6LoRH header (RPI-6LoRH) as described in [RFC8138]. 157 The 6TiSCH requirements for DetNet [I-D.thubert-6tisch-4detnet] 158 indicate that a 6TiSCH Track may leverage replication and elimination 159 as defined in DetNet. This specification enables this behavior as 160 follows: if a BIER-6LoRH is positioned right after a RPI-6LoRH, then 161 the BitString in the BIER-6LoRH applies to the context of the Track 162 indicated by the source or destination address of the packet and the 163 local Instance ID associated to the source or destination of the 164 packet. 166 4. The BIER-6LoRH encoding 168 The BIER 6LoRH (BIER-6LoRH) is a Critical 6LoWPAN Routing Header that 169 provides a variable-size container for a BitString such as, a but not 170 limited to, a BIER BitString. 172 The capability to parse the BIER BitString is necessary to forward 173 the packet so the Type cannot be ignored. 175 0 1 176 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ 178 |1|0|0| Control |6LoRHType 15-29| BitString | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ 181 Figure 1: The BIER-6LoRH 183 This specification provides a 5-bit Control field that can be used to 184 encode information that is specific to the BitString. The type and 185 size of the BitString are encoded in the 6LoRHType. 187 4.1. The Bit-by-bit BitStrings 189 In the bit-by-bit case, each bit is mapped in an unequivocal fashion 190 with a single addressable resource in the network. This may rapidly 191 lead to large BitStrings, and BIER allows to divide a network into 192 groups that partition the network so that a given BitString is 193 locally significant to one group only. This specification uses the 194 5-bits Control field to encode the group. 196 When groups are used, it may be that a packet is sent to different 197 groups at the same time. In that case, multiple BIER-6LoRH headers 198 can be prepended to a same packet, each one for a different group. 199 As the packet flows along the multicast distribution tree, a BIER- 200 6LoRH header that has no more destination in a given branch may be 201 removed to make the packet shorter. 203 The encoding value indicates the size of the BitString. The size of 204 the BitString used in a given packet is smallest that can represent 205 all of the bits that are set for this particular packet, so for a 206 same network various sizes may be used for different packets 207 depending on the destinations. 209 4.2. The Enumeration BitStrings 211 For unicast and when very few destinations are targeted for a given 212 message, it may be that it is more economical to list the bit offsets 213 one by one than it is to represent the full BitString that can hold 214 all of the bit offsets. 216 In the Enumeration case, a BitString actually encodes the offset of 217 one bit as an unsigned integer, using the number of bits indicated in 218 the control field, and BitStrings are concatenated without 219 intermediate padding. The overall concatenation must be aligned to a 220 byte boundary. To achieve this, trailing bits are added to the right 221 of the concatenation as padding to the next byte boundary. 223 To optimize the compression, the lower numbers can be expressed with 224 less bits, and multiple Enumeration BIER-6LoRH headers may be used to 225 encode offsets that require different numbers of bits for their 226 representation. 228 4.3. Bloom Filters 230 A Bloom Filter can be seen as an additional compression technique for 231 the bitString representation. A Bloom Filter may generate false 232 positives, which, in the case of BIER, result in undue forwarding of 233 a packet down a path where no listener exists. 235 As an example, the Constrained-Cast [I-D.ietf-roll-ccast] 236 specification employs Bloom Filters as a compact representation of a 237 match or non-match for elements in a set that may be larger than the 238 number of bits in the BitString. 240 In the case of a Bloom Filter, a number of Hash functions must be run 241 to obtain a multi-bit signature of an encoded element. This 242 specification uses the 5-bits Control field to signal an Identifier 243 of the set of Hash functions being used to generate a certain 244 BitString, so as to enable the migration from a set of Hash functions 245 to the next. 247 4.4. Types of BIER-6LoRH header 249 The Type of a BIER-6LoRH header indicates the size of the BitString 250 and whether the BitString is operated as an uncompressed bit-by-bit 251 mapping, as an enumeration, or as a Bloom filter. 253 +--------------+--------------+----------------------+--------------+ 254 | BitString | Encoding | Control field | BitString | 255 | Type | | | Size | 256 +--------------+--------------+----------------------+--------------+ 257 | 15 | bit-by-bit | Group ID | 8 bits | 258 +--------------+--------------+----------------------+--------------+ 259 | 16 | bit-by-bit | Group ID | 16 bits | 260 +--------------+--------------+----------------------+--------------+ 261 | 17 | bit-by-bit | Group ID | 32 bits | 262 +--------------+--------------+----------------------+--------------+ 263 | 18 | bit-by-bit | Group ID | 56 bits | 264 +--------------+--------------+----------------------+--------------+ 265 | 19 | bit-by-bit | Group ID | 96 bits | 266 +--------------+--------------+----------------------+--------------+ 267 | 20 | bit-by-bit | Group ID | 160 bits | 268 +--------------+--------------+----------------------+--------------+ 269 | 21 | bit-by-bit | Group ID | 256 bits | 270 +--------------+--------------+----------------------+--------------+ 271 | 22 | Enumeration | Number of elements | 4 bits | 272 +--------------+--------------+----------------------+--------------+ 273 | 23 | Enumeration | Number of elements | 6 bits | 274 +--------------+--------------+----------------------+--------------+ 275 | 24 | Enumeration | Number of elements | 8 bits | 276 +--------------+--------------+----------------------+--------------+ 277 | 25 | Bloom filter | Hash function Set ID | 8 bits | 278 +--------------+--------------+----------------------+--------------+ 279 | 26 | Bloom filter | Hash function Set ID | 16 bits | 280 +--------------+--------------+----------------------+--------------+ 281 | 27 | Bloom filter | Hash function Set ID | 48 bits | 282 +--------------+--------------+----------------------+--------------+ 283 | 28 | Bloom filter | Hash function Set ID | 96 bits | 284 +--------------+--------------+----------------------+--------------+ 285 | 29 | Bloom filter | Hash function Set ID | 160 bits | 286 +--------------+--------------+----------------------+--------------+ 288 Table 1: The BIER-6LoRH Types 290 In order to address a potentially large number of devices, the 291 BitString may grow very large. Yet, the maximum frame size for a 292 given MAC layer may limit the number of bits that can be dedicated to 293 routing. With this specification, a number of BIER-6LoRH headers of 294 a same type (bit-by-bit or Bloom filter) may be placed contiguously 295 in the packet. This results in a larger BitString that is the 296 concatenation of the BitStrings in the individual headers in the 297 order they are appearing in the packet. 299 5. Implementation Status 301 A research-stage implementation was developed at Cisco's Paris 302 Innovation Lab (PIRL) by Zacharie Brodard. It was implemented on 303 OpenWSN open-source firmware and tested on the OpenMote-CC2538 304 hardware. It implements the header types 15, 16, 17, 18 and 19 (bit- 305 by-bit encoding without group ID) in order to allow a BIER-TE 306 protocol over IEE802.15.4e. 308 Links: 310 github: https://github.com/zach-b/openwsn-fw/tree/BIER 312 OpenWSN firmware: https://openwsn.atlassian.net/wiki/pages/ 313 viewpage.action?pageId=688187 315 OpenMote hardware: http://www.openmote.com/ 317 6. Security Considerations 319 The security considerations of [RFC8138] apply. 321 7. IANA Considerations 323 This document extends the IANA registry created by [RFC8138] for the 324 6LoWPAN Routing Header Type, and adds the following values: 326 15..29 : BIER-6LoRH [RFCthis] 328 8. Acknowledgments 330 9. References 332 9.1. Normative References 334 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 335 Requirement Levels", BCP 14, RFC 2119, 336 DOI 10.17487/RFC2119, March 1997, 337 . 339 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 340 "Transmission of IPv6 Packets over IEEE 802.15.4 341 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 342 . 344 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 345 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 346 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 347 Low-Power and Lossy Networks", RFC 6550, 348 DOI 10.17487/RFC6550, March 2012, 349 . 351 [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power 352 Wireless Personal Area Network (6LoWPAN) Paging Dispatch", 353 RFC 8025, DOI 10.17487/RFC8025, November 2016, 354 . 356 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 357 "IPv6 over Low-Power Wireless Personal Area Network 358 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 359 April 2017, . 361 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 362 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 363 Explicit Replication (BIER)", RFC 8279, 364 DOI 10.17487/RFC8279, November 2017, 365 . 367 9.2. Informative References 369 [I-D.eckert-bier-te-arch] 370 Eckert, T., Cauchie, G., Braun, W., and M. Menth, "Traffic 371 Engineering for Bit Index Explicit Replication BIER-TE", 372 draft-eckert-bier-te-arch-06 (work in progress), November 373 2017. 375 [I-D.ietf-6tisch-architecture] 376 Thubert, P., "An Architecture for IPv6 over the TSCH mode 377 of IEEE 802.15.4", draft-ietf-6tisch-architecture-19 (work 378 in progress), December 2018. 380 [I-D.ietf-detnet-architecture] 381 Finn, N., Thubert, P., Varga, B., and J. Farkas, 382 "Deterministic Networking Architecture", draft-ietf- 383 detnet-architecture-10 (work in progress), December 2018. 385 [I-D.ietf-roll-ccast] 386 Bergmann, O., Bormann, C., Gerdes, S., and H. Chen, 387 "Constrained-Cast: Source-Routed Multicast for RPL", 388 draft-ietf-roll-ccast-01 (work in progress), October 2017. 390 [I-D.thubert-6tisch-4detnet] 391 Thubert, P., "6TiSCH requirements for DetNet", draft- 392 thubert-6tisch-4detnet-01 (work in progress), June 2015. 394 [I-D.thubert-bier-replication-elimination] 395 Thubert, P., Eckert, T., Brodard, Z., and H. Jiang, "BIER- 396 TE extensions for Packet Replication and Elimination 397 Function (PREF) and OAM", draft-thubert-bier-replication- 398 elimination-03 (work in progress), March 2018. 400 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 401 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 402 DOI 10.17487/RFC6282, September 2011, 403 . 405 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 406 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 407 2014, . 409 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 410 Constrained-Node Networks", RFC 7228, 411 DOI 10.17487/RFC7228, May 2014, 412 . 414 Authors' Addresses 416 Pascal Thubert (editor) 417 Cisco Systems 418 Village d'Entreprises Green Side 419 400, Avenue de Roumanille 420 Batiment T3 421 Biot - Sophia Antipolis 06410 422 FRANCE 424 Phone: +33 4 97 23 26 34 425 Email: pthubert@cisco.com 427 Zacharie Brodard 428 Ecole Polytechnique 429 Route de Saclay 430 Palaiseau 91128 431 FRANCE 433 Phone: +33 6 73 73 35 09 434 Email: zacharie.brodard@polytechnique.edu 435 Hao Jiang 436 Telecom Bretagne 437 2, rue de la Chataigneraie 438 Cesson-Sevigne 35510 439 FRANCE 441 Phone: +33 7 53 70 97 34 442 Email: hao.jiang@telecom-bretagne.eu 444 Geraldine Texier 445 Telecom Bretagne 446 2, rue de la Chataigneraie 447 Cesson-Sevigne 35510 448 FRANCE 450 Phone: +33 2 99 12 70 38 451 Email: geraldine.texier@telecom-bretagne.eu