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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to lower-maturity documents in RFCs) == Missing Reference: 'RFCthis' is mentioned on line 290, but not defined == Outdated reference: A later version (-30) exists of draft-ietf-6tisch-architecture-13 == Outdated reference: A later version (-13) exists of draft-ietf-detnet-architecture-04 == Outdated reference: A later version (-03) exists of draft-thubert-bier-replication-elimination-01 Summary: 0 errors (**), 0 flaws (~~), 6 warnings (==), 1 comment (--).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: July 20, 2018 Ecole Polytechnique 6 H. Jiang 7 G. Texier 8 Telecom Bretagne 9 January 16, 2018 11 A 6loRH for BitStrings 12 draft-thubert-6lo-bier-dispatch-04 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 July 20, 2018. 37 Copyright Notice 39 Copyright (c) 2018 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. Bloom Filters . . . . . . . . . . . . . . . . . . . . . . 5 60 4.3. Types of BIER-6LoRH header . . . . . . . . . . . . . . . 5 61 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 6 62 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 63 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 64 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 65 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 66 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 67 9.2. Informative References . . . . . . . . . . . . . . . . . 8 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 70 1. Introduction 72 The type of information that needs to be present in a packet inside 73 the LLN but not outside of the LLN varies with the routing operation, 74 but there is overall a need for an extensible compression technique 75 that would simplify the IP-in-IP encapsulation, when needed, and 76 optimally compress existing routing artifacts found in LLNs. 78 The 6LoWPAN Routing Header (6LoRH) [RFC8025] [RFC8138] is such a 79 technique, that extends the 6lo adaptation layer framework [RFC4944], 80 [RFC6282] so as to carry routing information for Route-over use 81 cases. The original specification includes the formats necessary for 82 RPL such as the Source Route Header (SRH) and is intended to be 83 extended for additional routing artifacts. 85 The Bit Index Explicit Replication (BIER), as introduced in the BIER 86 Architecture [I-D.ietf-bier-architecture], can be used as an 87 alternate artifact to route multicast as well as unicast traffic. 88 The Traffic Engineering for Bit Index Explicit Replication 89 [I-D.eckert-bier-te-arch] (BIER-TE) adds support for traffic 90 engineering by explicit hop-by-hop forwarding and loose hop 91 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 [I-D.ietf-bier-architecture]. A BitString indicates a 121 continuous sequence of bits indexed by an offset in the sequence. 122 The leftmost bit is bit 0 and corresponds to the value 0x80 of the 123 leftmost octet 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 15-24| 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 4.2. Bloom Filters 205 A Bloom Filter can be seen as an additional compression technique for 206 the bitString representation. A Bloom Filter may generate false 207 positives, which, in the case of BIER, result in undue forwarding of 208 a packet down a path where no listener exists. 210 As an example, the Constrained-Cast [I-D.ietf-roll-ccast] 211 specification employs Bloom Filters as a compact representation of a 212 match or non-match for elements in a set that may be larger than the 213 number of bits in the BitString. 215 In the case of a Bloom Filter, a number of Hash functions must be run 216 to obtain a multi-bit signature of an encoded element. This 217 specification uses the 5-bits Control field to signal an Identifier 218 of the set of Hash functions being used to generate a certain 219 BitString, so as to enable the migration from a set of Hash functions 220 to the next. 222 4.3. Types of BIER-6LoRH header 224 The Type of a BIER-6LoRH header indicates the size of the BitString 225 and whether the BitString is operated as an uncompressed bit-by-bit 226 mapping, or as a Bloom filter. 228 +--------------+--------------+----------------------+--------------+ 229 | BitString | Encoding | Control field | BitString | 230 | Type | | | Size | 231 +--------------+--------------+----------------------+--------------+ 232 | 15 | bit-by-bit | Group ID | 8 bits | 233 +--------------+--------------+----------------------+--------------+ 234 | 16 | bit-by-bit | Group ID | 16 bits | 235 +--------------+--------------+----------------------+--------------+ 236 | 17 | bit-by-bit | Group ID | 48 bits | 237 +--------------+--------------+----------------------+--------------+ 238 | 18 | bit-by-bit | Group ID | 96 bits | 239 +--------------+--------------+----------------------+--------------+ 240 | 19 | bit-by-bit | Group ID | 160 bits | 241 +--------------+--------------+----------------------+--------------+ 242 | 20 | Bloom filter | Hash function Set ID | 8 bits | 243 +--------------+--------------+----------------------+--------------+ 244 | 21 | Bloom filter | Hash function Set ID | 16 bits | 245 +--------------+--------------+----------------------+--------------+ 246 | 22 | Bloom filter | Hash function Set ID | 48 bits | 247 +--------------+--------------+----------------------+--------------+ 248 | 23 | Bloom filter | Hash function Set ID | 96 bits | 249 +--------------+--------------+----------------------+--------------+ 250 | 24 | Bloom filter | Hash function Set ID | 160 bits | 251 +--------------+--------------+----------------------+--------------+ 253 Table 1: The BIER-6LoRH Types 255 In order to address a potentially large number of devices, the 256 BitString may grow very large. Yet, the maximum frame size for a 257 given MAC layer may limit the number of bits that can be dedicated to 258 routing. With this specification, a number of BIER-6LoRH headers of 259 a same type (bit-by-bit or Bloom filter) may be placed contiguously 260 in the packet. This results in a larger BitString that is the 261 concatenation of the BitStrings in the individual headers in the 262 order they are appearing in the packet. 264 5. Implementation Status 266 A research-stage implementation was developed at Cisco's Paris 267 Innovation Lab (PIRL) by Zacharie Brodard. It was implemented on 268 OpenWSN open-source firmware and tested on the OpenMote-CC2538 269 hardware. It implements the header types 15, 16, 17, 18 and 19 (bit- 270 by-bit encoding without group ID) in order to allow a BIER-TE 271 protocol over IEE802.15.4e. 273 Links: 275 github: https://github.com/zach-b/openwsn-fw/tree/BIER 276 OpenWSN firmware: https://openwsn.atlassian.net/wiki/pages/ 277 viewpage.action?pageId=688187 279 OpenMote hardware: http://www.openmote.com/ 281 6. Security Considerations 283 The security considerations of [RFC8138] apply. 285 7. IANA Considerations 287 This document extends the IANA registry created by [RFC8138] for the 288 6LoWPAN Routing Header Type, and adds the following values: 290 15..24 : BIER-6LoRH [RFCthis] 292 8. Acknowledgments 294 9. References 296 9.1. Normative References 298 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 299 Requirement Levels", BCP 14, RFC 2119, 300 DOI 10.17487/RFC2119, March 1997, 301 . 303 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 304 "Transmission of IPv6 Packets over IEEE 802.15.4 305 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 306 . 308 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 309 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 310 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 311 Low-Power and Lossy Networks", RFC 6550, 312 DOI 10.17487/RFC6550, March 2012, 313 . 315 [RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power 316 Wireless Personal Area Network (6LoWPAN) Paging Dispatch", 317 RFC 8025, DOI 10.17487/RFC8025, November 2016, 318 . 320 [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, 321 "IPv6 over Low-Power Wireless Personal Area Network 322 (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, 323 April 2017, . 325 9.2. Informative References 327 [I-D.eckert-bier-te-arch] 328 Eckert, T., Cauchie, G., Braun, W., and M. Menth, "Traffic 329 Engineering for Bit Index Explicit Replication BIER-TE", 330 draft-eckert-bier-te-arch-06 (work in progress), November 331 2017. 333 [I-D.ietf-6tisch-architecture] 334 Thubert, P., "An Architecture for IPv6 over the TSCH mode 335 of IEEE 802.15.4", draft-ietf-6tisch-architecture-13 (work 336 in progress), November 2017. 338 [I-D.ietf-bier-architecture] 339 Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and 340 S. Aldrin, "Multicast using Bit Index Explicit 341 Replication", draft-ietf-bier-architecture-08 (work in 342 progress), September 2017. 344 [I-D.ietf-detnet-architecture] 345 Finn, N., Thubert, P., Varga, B., and J. Farkas, 346 "Deterministic Networking Architecture", draft-ietf- 347 detnet-architecture-04 (work in progress), October 2017. 349 [I-D.ietf-roll-ccast] 350 Bergmann, O., Bormann, C., Gerdes, S., and H. Chen, 351 "Constrained-Cast: Source-Routed Multicast for RPL", 352 draft-ietf-roll-ccast-01 (work in progress), October 2017. 354 [I-D.thubert-6tisch-4detnet] 355 Thubert, P., "6TiSCH requirements for DetNet", draft- 356 thubert-6tisch-4detnet-01 (work in progress), June 2015. 358 [I-D.thubert-bier-replication-elimination] 359 Thubert, P., Brodard, Z., and H. Jiang, "BIER-TE-based 360 OAM, Replication and Elimination", draft-thubert-bier- 361 replication-elimination-01 (work in progress), July 2017. 363 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 364 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 365 DOI 10.17487/RFC6282, September 2011, 366 . 368 [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and 369 Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January 370 2014, . 372 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 373 Constrained-Node Networks", RFC 7228, 374 DOI 10.17487/RFC7228, May 2014, 375 . 377 Authors' Addresses 379 Pascal Thubert (editor) 380 Cisco Systems 381 Village d'Entreprises Green Side 382 400, Avenue de Roumanille 383 Batiment T3 384 Biot - Sophia Antipolis 06410 385 FRANCE 387 Phone: +33 4 97 23 26 34 388 Email: pthubert@cisco.com 390 Zacharie Brodard 391 Ecole Polytechnique 392 Route de Saclay 393 Palaiseau 91128 394 FRANCE 396 Phone: +33 6 73 73 35 09 397 Email: zacharie.brodard@polytechnique.edu 399 Hao Jiang 400 Telecom Bretagne 401 2, rue de la Chataigneraie 402 Cesson-Sevigne 35510 403 FRANCE 405 Phone: +33 7 53 70 97 34 406 Email: hao.jiang@telecom-bretagne.eu 408 Geraldine Texier 409 Telecom Bretagne 410 2, rue de la Chataigneraie 411 Cesson-Sevigne 35510 412 FRANCE 414 Phone: +33 2 99 12 70 38 415 Email: geraldine.texier@telecom-bretagne.eu