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Lynn, Ed. 3 Internet-Draft Verizon Labs 4 Intended status: Standards Track J. Martocci 5 Expires: April 21, 2016 Johnson Controls 6 C. Neilson 7 Delta Controls 8 S. Donaldson 9 Honeywell 10 October 19, 2015 12 Transmission of IPv6 over MS/TP Networks 13 draft-ietf-6lo-6lobac-03 15 Abstract 17 Master-Slave/Token-Passing (MS/TP) is a medium access control method 18 for the RS-485 physical layer, which is used extensively in building 19 automation networks. This specification defines the frame format for 20 transmission of IPv6 packets and the method of forming link-local and 21 statelessly autoconfigured IPv6 addresses on MS/TP networks. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on April 21, 2016. 40 Copyright Notice 42 Copyright (c) 2015 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. MS/TP Mode for IPv6 . . . . . . . . . . . . . . . . . . . . . 6 59 3. Addressing Modes . . . . . . . . . . . . . . . . . . . . . . 6 60 4. Maximum Transmission Unit (MTU) . . . . . . . . . . . . . . . 6 61 5. LoBAC Adaptation Layer . . . . . . . . . . . . . . . . . . . 7 62 6. Stateless Address Autoconfiguration . . . . . . . . . . . . . 8 63 7. IPv6 Link Local Address . . . . . . . . . . . . . . . . . . . 8 64 8. Unicast Address Mapping . . . . . . . . . . . . . . . . . . . 9 65 9. Multicast Address Mapping . . . . . . . . . . . . . . . . . . 9 66 10. Header Compression . . . . . . . . . . . . . . . . . . . . . 10 67 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 68 12. Security Considerations . . . . . . . . . . . . . . . . . . . 10 69 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 70 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 71 Appendix A. Abstract MAC Interface . . . . . . . . . . . . . . . 13 72 Appendix B. Consistent Overhead Byte Stuffing [COBS] . . . . . . 16 73 Appendix C. Encoded CRC-32K [CRC32K] . . . . . . . . . . . . . . 19 74 Appendix D. Example 6LoBAC Packet Decode . . . . . . . . . . . . 21 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 77 1. Introduction 79 Master-Slave/Token-Passing (MS/TP) is a medium access control (MAC) 80 protocol for the RS-485 [TIA-485-A] physical layer, which is used 81 extensively in building automation networks. This specification 82 defines the frame format for transmission of IPv6 [RFC2460] packets 83 and the method of forming link-local and statelessly autoconfigured 84 IPv6 addresses on MS/TP networks. The general approach is to adapt 85 elements of the 6LoWPAN specifications [RFC4944], [RFC6282], and 86 [RFC6775] to constrained wired networks. 88 An MS/TP device is typically based on a low-cost microcontroller with 89 limited processing power and memory. Together with low data rates 90 and a small MAC address space, these constraints are similar to those 91 faced in 6LoWPAN networks and suggest some elements of that solution 92 might be leveraged. MS/TP differs significantly from 6LoWPAN in at 93 least three respects: a) MS/TP devices typically have a continuous 94 source of power, b) all MS/TP devices on a segment can communicate 95 directly so there are no hidden node or mesh routing issues, and c) 96 recent changes to MS/TP provide support for large payloads, 97 eliminating the need for fragmentation and reassembly below IPv6. 99 The following sections provide a brief overview of MS/TP, then 100 describe how to form IPv6 addresses and encapsulate IPv6 packets in 101 MS/TP frames. This document also specifies a header compression 102 mechanism, based on [RFC6282], that is REQUIRED in order to reduce 103 latency and make IPv6 practical on MS/TP networks. 105 1.1. Requirements Language 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 109 document are to be interpreted as described in [RFC2119]. 111 1.2. Abbreviations Used 113 ASHRAE: American Society of Heating, Refrigerating, and Air- 114 Conditioning Engineers (http://www.ashrae.org) 116 BACnet: An ISO/ANSI/ASHRAE Standard Data Communication Protocol 117 for Building Automation and Control Networks 119 CRC: Cyclic Redundancy Check 121 MAC: Medium Access Control 123 MSDU: MAC Service Data Unit (MAC client data) 125 MTU: Maximum Transmission Unit 127 UART: Universal Asynchronous Transmitter/Receiver 129 1.3. MS/TP Overview 131 This section provides a brief overview of MS/TP, which is specified 132 in ANSI/ASHRAE 135-2012 (BACnet) Clause 9 [Clause9] and included 133 herein by reference. BACnet [Clause9] also covers physical layer 134 deployment options. 136 MS/TP is designed to enable multidrop networks over shielded twisted 137 pair wiring. It can support network segments up to 1000 meters in 138 length at a data rate of 115,200 baud, or segments up to 1200 meters 139 in length at lower baud rates. An MS/TP link requires only a UART, 140 an RS-485 [TIA-485-A] transceiver with a driver that can be disabled, 141 and a 5ms resolution timer. These features make MS/TP a cost- 142 effective field bus for the most numerous and least expensive devices 143 in a building automation network. 145 The differential signaling used by [TIA-485-A] requires a contention- 146 free MAC. MS/TP uses a token to control access to a multidrop bus. 147 A master node may initiate the transmission of a data frame when it 148 holds the token. After sending at most a configured maximum number 149 of data frames, a master node passes the token to the next master 150 node (as determined by MAC address). Slave nodes do not support the 151 frame format required to convey IPv6 over MS/TP and therefore SHALL 152 NOT be considered part of this specification. 154 MS/TP COBS-encoded* frames have the following format: 156 0 1 2 3 157 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | 0x55 | 0xFF | Frame Type* | DA | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | SA | Length (MS octet first) | Header CRC | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 . . 164 . Encoded Data* (2 - 1506 octets) . 165 . . 166 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | | Encoded CRC-32K* (5 octets) | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+ 169 | | optional 0xFF | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 Figure 1: MS/TP COBS-Encoded Frame Format 174 *NOTE: BACnet Addendum 135-2012an [Addendum_an] defines a range of 175 Frame Type values to designate frames that contain data and data CRC 176 fields encoded using Consistent Overhead Byte Stuffing [COBS] (see 177 Appendix B). The purpose of COBS encoding is to eliminate preamble 178 sequences from the Encoded Data and Encoded CRC-32K fields. The 179 maximum length of an MSDU as defined by this specification is 1500 180 octets (before encoding). The Encoded Data is covered by a 32-bit 181 CRC [CRC32K] (see Appendix C), which is itself then COBS encoded. 183 MS/TP COBS-encoded frame fields have the following descriptions: 185 Preamble two octet preamble: 0x55, 0xFF 186 Frame Type one octet 187 Destination Address one octet address 188 Source Address one octet address 189 Length two octets, most significant octet first 190 Header CRC one octet 191 Encoded Data 2 - 1506 octets (see Appendix B) 192 Encoded CRC-32K five octets (see Appendix C) 193 (pad) (optional) at most one octet of trailer: 0xFF 195 The Frame Type is used to distinguish between different types of MAC 196 frames. The types relevant to this specification (in decimal) are: 198 0 Token 199 1 Poll For Master 200 2 Reply To Poll For Master 201 ... 202 34 IPv6 over MS/TP (LoBAC) Encapsulation 204 Frame Types 8 - 31 and 35 - 127 are reserved for assignment by 205 ASHRAE. Frame Types 32 - 127 designate COBS-encoded frames and MUST 206 convey Encoded Data and Encoded CRC-32K fields. All master nodes 207 MUST understand Token, Poll For Master, and Reply to Poll For Master 208 control frames. See Section 2 for additional details. 210 The Destination and Source Addresses are each one octet in length. 211 See Section 3 for additional details. 213 For COBS-encoded frames, the Length field specifies the combined 214 length of the [COBS] Encoded Data and Encoded CRC-32K fields in 215 octets, minus two. (This adjustment is required for backward 216 compatibility with legacy MS/TP devices.) See Section 4 and 217 Appendices for additional details. 219 The Header CRC field covers the Frame Type, Destination Address, 220 Source Address, and Length fields. The Header CRC generation and 221 check procedures are specified in BACnet [Clause9]. 223 1.4. Goals and Constraints 225 The primary goal of this specification is to enable IPv6 directly on 226 wired end devices in building automation and control networks by 227 leveraging existing standards to the greatest extent possible. A 228 secondary goal is to co-exist with legacy MS/TP implementations. 229 Only the minimum changes necessary to support IPv6 over MS/TP were 230 specified in BACnet [Addendum_an] (see Note in Section 1.3). 232 In order to co-exist with legacy devices, no changes are permitted to 233 the MS/TP addressing modes, frame header format, control frames, or 234 Master Node state machine as specified in BACnet [Clause9]. 236 2. MS/TP Mode for IPv6 238 ASHRAE has assigned an MS/TP Frame Type value of 34 to indicate IPv6 239 over MS/TP (LoBAC) Encapsulation. This falls within the range of 240 values that designate COBS-encoded data frames. 242 All MS/TP master nodes (including those that support IPv6) must 243 understand Token, Poll For Master, and Reply to Poll For Master 244 control frames and support the Master Node state machine as specified 245 in BACnet [Clause9]. MS/TP master nodes that support IPv6 must also 246 support the Receive Frame state machine as specified in [Clause9] and 247 extended by BACnet [Addendum_an]. 249 All MS/TP nodes that support IPv6 MUST support a data rate of 115,200 250 baud and MAY optionally support lower data rates as defined in BACnet 251 [Clause9]. 253 3. Addressing Modes 255 MS/TP node (MAC) addresses are one octet in length. The method of 256 assigning MAC addresses is outside the scope of this specification. 257 However, each MS/TP node on the link MUST have a unique address in 258 order to ensure correct MAC operation. 260 BACnet [Clause9] specifies that addresses 0 through 127 are valid for 261 master nodes. The method specified in Section 6 for creating a MAC- 262 layer-derived Interface Identifier (IID) ensures that an IID of all 263 zeros can never result. 265 A Destination Address of 255 (all nodes) indicates a MAC-layer 266 broadcast. MS/TP does not support multicast, therefore all IPv6 267 multicast packets SHOULD be broadcast at the MAC layer and filtered 268 at the IPv6 layer. A Source Address of 255 MUST NOT be used. 270 This specification assumes that at most one unique local and/or 271 global IPv6 prefix is assigned to each MS/TP segment. Hosts learn 272 IPv6 prefixes via router advertisements according to [RFC4861]. 274 4. Maximum Transmission Unit (MTU) 276 BACnet [Addendum_an] supports MSDUs up to 2032 octets in length. 277 This specification defines an MSDU length of at least 1280 octets and 278 at most 1500 octets (before encoding). This is sufficient to convey 279 the minimum MTU required by IPv6 [RFC2460] without the need for link- 280 layer fragmentation and reassembly. Support for an MSDU length of 281 1500 octets is RECOMMENDED. 283 5. LoBAC Adaptation Layer 285 The relatively low data rates of MS/TP indicate header compression as 286 a means to reduce latency. This section specifies an adaptation 287 layer to support compressed IPv6 headers and the compression format 288 is specified in Section 10. 290 Implementations MAY also support Generic Header Compression (GHC) 291 [RFC7400] for transport layer headers. A node implementing [RFC7400] 292 MUST probe its peers for GHC support before applying GHC. 294 The encapsulation format defined in this section (subsequently 295 referred to as the "LoBAC" encapsulation) comprises the MSDU of an 296 IPv6 over MS/TP frame. The LoBAC payload (i.e., an IPv6 packet) 297 follows an encapsulation header stack. LoBAC is a subset of the 298 LoWPAN encapsulation defined in [RFC4944] and extended by [RFC6282], 299 therefore the use of "LOWPAN" in literals below is intentional. The 300 primary difference between LoWPAN and LoBAC is omission of the Mesh, 301 Broadcast, Fragmentation, and LOWPAN_HC1 headers. 303 All LoBAC encapsulated datagrams transmitted over MS/TP are prefixed 304 by an encapsulation header stack consisting of a Dispatch value 305 followed by zero or more header fields. The only sequence currently 306 defined for LoBAC is the LOWPAN_IPHC header followed by payload, as 307 shown below: 309 +---------------+---------------+------...-----+ 310 | IPHC Dispatch | IPHC Header | Payload | 311 +---------------+---------------+------...-----+ 313 Figure 2: A LoBAC Encapsulated LOWPAN_IPHC Compressed IPv6 Datagram 315 The Dispatch value may be treated as an unstructured namespace. Only 316 a single pattern is used to represent current LoBAC functionality. 318 Pattern Header Type 319 +------------+-----------------------------------------------------+ 320 | 01 1xxxxx | LOWPAN_IPHC - LOWPAN_IPHC compressed IPv6 [RFC6282] | 321 +------------+-----------------------------------------------------+ 323 Figure 3: LoBAC Dispatch Value Bit Pattern 325 Other IANA-assigned 6LoWPAN Dispatch values do not apply to this 326 specification. 328 6. Stateless Address Autoconfiguration 330 This section defines how to obtain an IPv6 Interface Identifier. The 331 general procedure for creating a MAC-address-derived IID is described 332 in [RFC4291] Appendix A, "Creating Modified EUI-64 Format Interface 333 Identifiers", as updated by [RFC7136]. 335 The IID SHOULD NOT embed an [EUI-64] or any other globally unique 336 hardware identifier assigned to a device (see Section 12). 338 The Interface Identifier for link-local addresses SHOULD be formed by 339 concatenating a node's' 8-bit MS/TP MAC address to the seven octets 340 0x00, 0x00, 0x00, 0xFF, 0xFE, 0x00, 0x00. For example, an MS/TP MAC 341 address of hexadecimal value 0x4F results in the following IID: 343 |0 1|1 3|3 4|4 6| 344 |0 5|6 1|2 7|8 3| 345 +----------------+----------------+----------------+----------------+ 346 |0000000000000000|0000000011111111|1111111000000000|0000000001001111| 347 +----------------+----------------+----------------+----------------+ 349 This is the RECOMMENDED method of forming an IID for use in link- 350 local addresses, as it affords the most efficient header compression 351 provided by the LOWPAN_IPHC [RFC6282] format specified in Section 10. 353 A 64-bit privacy IID is RECOMMENDED for routable addresses and SHOULD 354 be locally generated according to [I-D.ietf-6man-default-iids]. A 355 node that generates a 64-bit privacy IID MUST register it with its 356 local router(s) by sending a Neighbor Solicitation (NS) message with 357 the Address Registration Option (ARO) and process Neighbor 358 Advertisements (NA) according to [RFC6775]. 360 An IPv6 address prefix used for stateless autoconfiguration [RFC4862] 361 of an MS/TP interface MUST have a length of 64 bits. 363 7. IPv6 Link Local Address 365 The IPv6 link-local address [RFC4291] for an MS/TP interface is 366 formed by appending the Interface Identifier, as defined above, to 367 the prefix FE80::/64. 369 10 bits 54 bits 64 bits 370 +----------+-----------------------+----------------------------+ 371 |1111111010| (zeros) | Interface Identifier | 372 +----------+-----------------------+----------------------------+ 374 8. Unicast Address Mapping 376 The address resolution procedure for mapping IPv6 non-multicast 377 addresses into MS/TP MAC-layer addresses follows the general 378 description in Section 7.2 of [RFC4861], unless otherwise specified. 380 The Source/Target Link-layer Address option has the following form 381 when the addresses are 8-bit MS/TP MAC-layer (node) addresses. 383 0 1 384 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | Type | Length=1 | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | 0x00 | MS/TP Address | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | | 391 + Padding (all zeros) + 392 | | 393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 Option fields: 397 Type: 399 1: for Source Link-layer address. 401 2: for Target Link-layer address. 403 Length: This is the length of this option (including the type and 404 length fields) in units of 8 octets. The value of this field is 1 405 for 8-bit MS/TP MAC addresses. 407 MS/TP Address: The 8-bit address in canonical bit order [RFC2469]. 408 This is the unicast address the interface currently responds to. 410 9. Multicast Address Mapping 412 All IPv6 multicast packets SHOULD be sent to MS/TP Destination 413 Address 255 (broadcast) and filtered at the IPv6 layer. When 414 represented as a 16-bit address in a compressed header (see 415 Section 10), it MUST be formed by padding on the left with a zero: 417 0 1 418 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 | 0x00 | 0xFF | 421 +-+-+-+-+-+-+-+-+---------------+ 423 10. Header Compression 425 LoBAC uses LOWPAN_IPHC IPv6 compression, which is specified in 426 [RFC6282] and included herein by reference. This section will simply 427 identify substitutions that should be made when interpreting the text 428 of [RFC6282]. 430 In general the following substitutions should be made: 432 - Replace instances of "6LoWPAN" with "MS/TP network" 434 - Replace instances of "IEEE 802.15.4 address" with "MS/TP address" 436 When a 16-bit address is called for (i.e., an IEEE 802.15.4 "short 437 address") it MUST be formed by padding the MS/TP address to the left 438 with a zero: 440 0 1 441 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 | 0x00 | MS/TP address | 444 +-+-+-+-+-+-+-+-+---------------+ 446 If LOWPAN_IPHC compression [RFC6282] is used with context, the border 447 router(s) directly attached to the MS/TP segment MUST disseminate the 448 6LoWPAN Context Option (6CO) according to [RFC6775], Section 7.2. 450 11. IANA Considerations 452 This document uses values previously reserved by [RFC4944] and 453 [RFC6282] and makes no further requests of IANA. 455 Note to RFC Editor: this section may be removed upon publication. 457 12. Security Considerations 459 The security and privacy implications of embedding a link-layer 460 address in an IPv6 IID are discussed in 461 [I-D.ietf-6man-ipv6-address-generation-privacy]. The issue most 462 relevant to MS/TP networks is address scanning. This is mainly an 463 issue for routable addresses and probably only for those hosted on 464 the global Internet. This specification RECOMMENDS mitigating this 465 threat according to [I-D.ietf-6man-default-iids]. 467 13. Acknowledgments 469 We are grateful to the authors of [RFC4944] and members of the IETF 470 6LoWPAN working group; this document borrows liberally from their 471 work. Ralph Droms and Brian Haberman provided indispensable guidance 472 and support from the outset. Peter van der Stok, James Woodyatt, and 473 Carsten Bormann provided detailed reviews. Stuart Cheshire invented 474 the very clever COBS encoding. Michael Osborne made the critical 475 observation that seperately encoding the data and CRC32K fields would 476 allow the CRC to be calculated on-the-fly. Alexandru Petrescu, Brian 477 Frank, Geoff Mulligan, and Don Sturek offered valuable comments. 479 14. References 481 14.1. Normative References 483 [Addendum_an] 484 ASHRAE, "ANSI/ASHRAE Addenda an, at, au, av, aw, ax, and 485 az to ANSI/ASHRAE Standard 135-2012, BACnet - A Data 486 Communication Protocol for Building Automation and Control 487 Networks", July 2014, 488 . 491 [Clause9] American Society of Heating, Refrigerating, and Air- 492 Conditioning Engineers, "BACnet - A Data Communication 493 Protocol for Building Automation and Control Networks", 494 ANSI/ASHRAE 135-2012 (Clause 9), March 2013. 496 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 497 Requirement Levels", BCP 14, RFC 2119, 498 DOI 10.17487/RFC2119, March 1997, 499 . 501 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 502 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 503 December 1998, . 505 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 506 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 507 2006, . 509 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 510 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 511 DOI 10.17487/RFC4861, September 2007, 512 . 514 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 515 Address Autoconfiguration", RFC 4862, 516 DOI 10.17487/RFC4862, September 2007, 517 . 519 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 520 "Transmission of IPv6 Packets over IEEE 802.15.4 521 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 522 . 524 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 525 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 526 DOI 10.17487/RFC6282, September 2011, 527 . 529 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 530 Bormann, "Neighbor Discovery Optimization for IPv6 over 531 Low-Power Wireless Personal Area Networks (6LoWPANs)", 532 RFC 6775, DOI 10.17487/RFC6775, November 2012, 533 . 535 [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 536 Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, 537 February 2014, . 539 [RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for 540 IPv6 over Low-Power Wireless Personal Area Networks 541 (6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November 542 2014, . 544 14.2. Informative References 546 [COBS] Cheshire, S. and M. Baker, "Consistent Overhead Byte 547 Stuffing", IEEE/ACM TRANSACTIONS ON NETWORKING, VOL.7, 548 NO.2 , April 1999, 549 . 551 [CRC32K] Koopman, P., "32-Bit Cyclic Redundancy Codes for Internet 552 Applications", IEEE/IFIP International Conference on 553 Dependable Systems and Networks (DSN 2002) , June 2002, 554 . 557 [EUI-64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) 558 Registration Authority", March 1997, 559 . 562 [I-D.ietf-6man-default-iids] 563 Gont, F., Cooper, A., Thaler, D., and S. LIU, 564 "Recommendation on Stable IPv6 Interface Identifiers", 565 draft-ietf-6man-default-iids-08 (work in progress), 566 October 2015. 568 [I-D.ietf-6man-ipv6-address-generation-privacy] 569 Cooper, A., Gont, F., and D. Thaler, "Privacy 570 Considerations for IPv6 Address Generation Mechanisms", 571 draft-ietf-6man-ipv6-address-generation-privacy-08 (work 572 in progress), September 2015. 574 [IEEE.802.3] 575 "Information technology - Telecommunications and 576 information exchange between systems - Local and 577 metropolitan area networks - Specific requirements - Part 578 3: Carrier Sense Multiple Access with Collision Detection 579 (CMSA/CD) Access Method and Physical Layer 580 Specifications", IEEE Std 802.3-2012, December 2012, 581 . 583 [RFC2469] Narten, T. and C. Burton, "A Caution On The Canonical 584 Ordering Of Link-Layer Addresses", RFC 2469, 585 DOI 10.17487/RFC2469, December 1998, 586 . 588 [TIA-485-A] 589 Telecommunications Industry Association, "TIA-485-A, 590 Electrical Characteristics of Generators and Receivers for 591 Use in Balanced Digital Multipoint Systems (ANSI/TIA/EIA- 592 485-A-98) (R2003)", March 2003. 594 Appendix A. Abstract MAC Interface 596 This Appendix is informative and not part of the standard. 598 BACnet [Clause9] defines support for MAC-layer clients through its 599 SendFrame and ReceivedDataNoReply procedures. However, it does not 600 define a network-protocol independent abstract interface for the MAC. 601 This is provided below as an aid to implementation. 603 A.1. MA-DATA.request 605 A.1.1. Function 607 This primitive defines the transfer of data from a MAC client entity 608 to a single peer entity or multiple peer entities in the case of a 609 broadcast address. 611 A.1.2. Semantics of the Service Primitive 613 The semantics of the primitive are as follows: 615 MA-DATA.request ( 616 destination_address, 617 source_address, 618 data, 619 priority, 620 type 621 ) 623 The 'destination_address' parameter may specify either an individual 624 or a broadcast MAC entity address. It must contain sufficient 625 information to create the Destination Address field (see Section 1.3) 626 that is prepended to the frame by the local MAC sublayer entity. The 627 'source_address' parameter, if present, must specify an individual 628 MAC address. If the source_address parameter is omitted, the local 629 MAC sublayer entity will insert a value associated with that entity. 631 The 'data' parameter specifies the MAC service data unit (MSDU) to be 632 transferred by the MAC sublayer entity. There is sufficient 633 information associated with the MSDU for the MAC sublayer entity to 634 determine the length of the data unit. 636 The 'priority' parameter specifies the priority desired for the data 637 unit transfer. The priority parameter is ignored by MS/TP. 639 The 'type' parameter specifies the value of the MS/TP Frame Type 640 field that is prepended to the frame by the local MAC sublayer 641 entity. 643 A.1.3. When Generated 645 This primitive is generated by the MAC client entity whenever data 646 shall be transferred to a peer entity or entities. This can be in 647 response to a request from higher protocol layers or from data 648 generated internally to the MAC client, such as a Token frame. 650 A.1.4. Effect on Receipt 652 Receipt of this primitive will cause the MAC entity to insert all MAC 653 specific fields, including Destination Address, Source Address, Frame 654 Type, and any fields that are unique to the particular media access 655 method, and pass the properly formed frame to the lower protocol 656 layers for transfer to the peer MAC sublayer entity or entities. 658 A.2. MA-DATA.indication 660 A.2.1. Function 662 This primitive defines the transfer of data from the MAC sublayer 663 entity to the MAC client entity or entities in the case of a 664 broadcast address. 666 A.2.2. Semantics of the Service Primitive 668 The semantics of the primitive are as follows: 670 MA-DATA.indication ( 671 destination_address, 672 source_address, 673 data, 674 priority, 675 type 676 ) 678 The 'destination_address' parameter may be either an individual or a 679 broadcast address as specified by the Destination Address field of 680 the incoming frame. The 'source_address' parameter is an individual 681 address as specified by the Source Address field of the incoming 682 frame. 684 The 'data' parameter specifies the MAC service data unit (MSDU) as 685 received by the local MAC entity. There is sufficient information 686 associated with the MSDU for the MAC sublayer client to determine the 687 length of the data unit. 689 The 'priority' parameter specifies the priority desired for the data 690 unit transfer. The priority parameter is ignored by MS/TP. 692 The 'type' parameter is the value of the MS/TP Frame Type field of 693 the incoming frame. 695 A.2.3. When Generated 697 The MA_DATA.indication is passed from the MAC sublayer entity to the 698 MAC client entity or entities to indicate the arrival of a frame to 699 the local MAC sublayer entity that is destined for the MAC client. 700 Such frames are reported only if they are validly formed, received 701 without error, and their destination address designates the local MAC 702 entity. Frames destined for the MAC Control sublayer are not passed 703 to the MAC client. 705 A.2.4. Effect on Receipt 707 The effect of receipt of this primitive by the MAC client is 708 unspecified. 710 Appendix B. Consistent Overhead Byte Stuffing [COBS] 712 This Appendix is informative and not part of the standard. 714 BACnet [Addendum_an] corrects a long-standing issue with the MS/TP 715 specification; namely that preamble sequences were not escaped 716 whenever they appeared in the Data or Data CRC fields. In rare 717 cases, this resulted in dropped frames due to loss of frame 718 synchronization. The solution is to encode the Data and 32-bit Data 719 CRC fields before transmission using Consistent Overhead Byte 720 Stuffing [COBS] and decode these fields upon reception. 722 COBS is a run-length encoding method that nominally removes '0x00' 723 octets from its input. Any selected octet value may be removed by 724 XOR'ing that value with each octet of the COBS output. BACnet 725 [Addendum_an] specifies the preamble octet '0x55' for removal. 727 The minimum overhead of COBS is one ectet per encoded field. The 728 worst-case overhead in long fields is bounded to one octet in 254, or 729 less than 0.4%, as described in [COBS]. 731 Frame encoding proceeds logically in two passes. The Encoded Data 732 field is prepared by passing the MSDU through the COBS encoder and 733 XOR'ing the preamble octet '0x55' with each octet of the output. The 734 Encoded CRC-32K field is then prepared by calculating a CRC-32K over 735 the Encoded Data field and formatting it for transmission as 736 described in Appendix C. The combined length of these fields, minus 737 two octets for compatibility with existing MS/TP devices, is placed 738 in the MS/TP header Length field before transmission. 740 Example COBS encoder and decoder functions are shown below for 741 illustration. Complete examples of use and test vectors are provided 742 in BACnet [Addendum_an]. 744 #include 745 #include 747 #define CRC32K_INITIAL_VALUE (0xFFFFFFFF) 748 #define MSTP_PREAMBLE_X55 (0x55) 750 /* 751 * Encodes 'length' octets of data located at 'from' and 752 * writes one or more COBS code blocks at 'to', removing any 753 * 'mask' octets that may present be in the encoded data. 754 * Returns the length of the encoded data. 755 */ 757 size_t 758 cobs_encode (uint8_t *to, const uint8_t *from, size_t length, 759 uint8_t mask) 760 { 761 size_t code_index = 0; 762 size_t read_index = 0; 763 size_t write_index = 1; 764 uint8_t code = 1; 765 uint8_t data, last_code; 767 while (read_index < length) { 768 data = from[read_index++]; 769 /* 770 * In the case of encountering a non-zero octet in the data, 771 * simply copy input to output and increment the code octet. 772 */ 773 if (data != 0) { 774 to[write_index++] = data ^ mask; 775 code++; 776 if (code != 255) 777 continue; 778 } 779 /* 780 * In the case of encountering a zero in the data or having 781 * copied the maximum number (254) of non-zero octets, store 782 * the code octet and reset the encoder state variables. 783 */ 784 last_code = code; 785 to[code_index] = code ^ mask; 786 code_index = write_index++; 787 code = 1; 788 } 789 /* 790 * If the last chunk contains exactly 254 non-zero octets, then 791 * this exception is handled above (and returned length must be 792 * adjusted). Otherwise, encode the last chunk normally, as if 793 * a "phantom zero" is appended to the data. 794 */ 795 if ((last_code == 255) && (code == 1)) 796 write_index--; 797 else 798 to[code_index] = code ^ mask; 800 return write_index; 802 } 804 #include 805 #include 807 #define CRC32K_INITIAL_VALUE (0xFFFFFFFF) 808 #define MSTP_PREAMBLE_X55 (0x55) 810 /* 811 * Decodes 'length' octets of data located at 'from' and 812 * writes the original client data at 'to', restoring any 813 * 'mask' octets that may present in the encoded data. 814 * Returns the length of the encoded data or zero if error. 815 */ 816 size_t 817 cobs_decode (uint8_t *to, const uint8_t *from, size_t length, 818 uint8_t mask) 819 { 820 size_t read_index = 0; 821 size_t write_index = 0; 822 uint8_t code, last_code; 824 while (read_index < length) { 825 code = from[read_index] ^ mask; 826 last_code = code; 827 /* 828 * Sanity check the encoding to prevent the while() loop below 829 * from overrunning the output buffer. 830 */ 831 if (read_index + code > length) 832 return 0; 834 read_index++; 835 while (--code > 0) 836 to[write_index++] = from[read_index++] ^ mask; 837 /* 838 * Restore the implicit zero at the end of each decoded block 839 * except when it contains exactly 254 non-zero octets or the 840 * end of data has been reached. 841 */ 842 if ((last_code != 255) && (read_index < length)) 843 to[write_index++] = 0; 844 } 845 return write_index; 846 } 848 Appendix C. Encoded CRC-32K [CRC32K] 850 This Appendix is informative and not part of the standard. 852 Extending the payload of MS/TP to 1500 octets required upgrading the 853 Data CRC from 16 bits to 32 bits. P.Koopman has authored several 854 papers on evaluating CRC polynomials for network applications. In 855 [CRC32K], he surveyed the entire 32-bit polynomial space and noted 856 some that exceed the [IEEE.802.3] polynomial in performance. BACnet 857 [Addendum_an] specifies the CRC-32K (Koopman) polynomial. 859 The specified use of the calc_crc32K() function is as follows. 860 Before a frame is transmitted, 'crc_value' is initialized to all 861 ones. After passing each octet of the [COBS] Encoded Data through 862 the function, the ones complement of the resulting 'crc_value' is 863 arranged in LSB-first order and is itself [COBS] encoded. The length 864 of the resulting Encoded CRC-32K field is always five octets. 866 Upon reception of a frame, 'crc_value' is initialized to all ones. 867 The octets of the Encoded Data field are accumulated by the 868 calc_crc32K() function before decoding. The Encoded CRC-32K field is 869 then decoded and the resulting four octets are accumulated by the 870 calc_crc32K() function. If the result is the expected residue value 871 'CRC32K_RESIDUE', then the frame was received correctly. 873 An example CRC-32K function in shown below for illustration. 874 Complete examples of use and test vectors are provided in BACnet 875 [Addendum_an]. 877 #include 879 /* See BACnet Addendum 135-2012an, section G.3.2 */ 880 #define CRC32K_INITIAL_VALUE (0xFFFFFFFF) 881 #define CRC32K_RESIDUE (0x0843323B) 883 /* CRC-32K polynomial, 1 + x**1 + ... + x**30 (+ x**32) */ 884 #define CRC32K_POLY (0xEB31D82E) 886 /* 887 * Accumulate 'data_value' into the CRC in 'crc_value'. 888 * Return updated CRC. 889 * 890 * Note: crcValue must be set to CRC32K_INITIAL_VALUE 891 * before initial call. 892 */ 893 uint32_t 894 calc_crc32K (uint8_t data_value, uint32_t crc_value) 895 { 896 int b; 898 for (b = 0; b < 8; b++) { 899 if ((data_value & 1) ^ (crc_value & 1)) { 900 crc_value >>= 1; 901 crc_value ^= CRC32K_POLY; 902 } else { 903 crc_value >>= 1; 904 } 905 data_value >>= 1; 906 } 907 return crc_value; 908 } 910 Appendix D. Example 6LoBAC Packet Decode 912 This Appendix is informative and not part of the standard. 914 No. Time Source Destination 915 5161 8.816048 aaaa::1 aaaa::ff:fe00:1 916 Protocol Length Info 917 ICMPv6 547 Echo (ping) request id=0x2ee5, seq=2, 918 hop limit=63 (reply in 5165) 920 Frame 5161: 547 bytes on wire (4376 bits), 547 bytes captured 921 (4376 bits) on interface 0 922 Interface id: 0 (/tmp/pipe) 923 Encapsulation type: BACnet MS/TP (63) 924 Arrival Time: Sep 3, 2015 19:46:44.377881000 EDT 925 [Time shift for this packet: 0.000000000 seconds] 926 Epoch Time: 1441324004.377881000 seconds 927 [Time delta from previous captured frame: 0.050715000 seconds] 928 [Time delta from previous displayed frame: 0.050715000 seconds] 929 [Time since reference or first frame: 8.816048000 seconds] 930 Frame Number: 5161 931 Frame Length: 547 bytes (4376 bits) 932 Capture Length: 547 bytes (4376 bits) 933 [Frame is marked: False] 934 [Frame is ignored: False] 935 [Protocols in frame: mstp:6lowpan:ipv6:ipv6.nxt:icmpv6:data] 936 [Coloring Rule Name: ICMP] 937 [Coloring Rule String: icmp || icmpv6] 938 BACnet MS/TP, Src (2), Dst (1), IPv6 Encapsulation 939 Preamble 55: 0x55 940 Preamble FF: 0xff 941 Frame Type: IPv6 Encapsulation (34) 942 Destination Address: 1 943 Source Address: 2 944 Length: 537 945 Header CRC: 0x1c [correct] 946 [Good: True] 947 [Bad: False] 948 Extended Data CRC: 0x9e7259e2 [correct] 949 6LoWPAN 950 IPHC Header 951 011. .... = Pattern: IP header compression (0x03) 952 ...1 1... .... .... = Traffic class and flow label: 953 Version, traffic class, and flow label 954 compressed (0x0003) 955 .... .0.. .... .... = Next header: Inline 956 .... ..00 .... .... = Hop limit: Inline (0x0000) 957 .... .... 1... .... = Context identifier extension: True 958 .... .... .1.. .... = Source address compression: Stateful 959 .... .... ..01 .... = Source address mode: 960 64-bits inline (0x0001) 961 .... .... .... 0... = Multicast address compression: False 962 .... .... .... .1.. = Destination address compression: 963 Stateful 964 .... .... .... ..10 = Destination address mode: 965 16-bits inline (0x0002) 966 0000 .... = Source context identifier: 0x00 967 .... 0000 = Destination context identifier: 0x00 968 [Source context: aaaa:: (aaaa::)] 969 [Destination context: aaaa:: (aaaa::)] 970 Next header: ICMPv6 (0x3a) 971 Hop limit: 63 972 Source: aaaa::1 (aaaa::1) 973 Destination: aaaa::ff:fe00:1 (aaaa::ff:fe00:1) 974 Internet Protocol Version 6, Src: aaaa::1 (aaaa::1), 975 Dst: aaaa::ff:fe00:1 (aaaa::ff:fe00:1) 976 0110 .... .... .... .... .... .... .... = Version: 6 977 .... 0000 0000 .... .... .... .... .... = Traffic class: 978 0x00000000 979 .... 0000 00.. .... .... .... .... .... = Differentiated 980 Services Field: 981 Default (0x00000000) 982 .... .... ..0. .... .... .... .... .... = ECN-Capable Transport 983 (ECT): Not set 984 .... .... ...0 .... .... .... .... .... = ECN-CE: Not set 985 .... .... .... 0000 0000 0000 0000 0000 = Flowlabel: 0x00000000 986 Payload length: 518 987 Next header: ICMPv6 (58) 988 Hop limit: 63 989 Source: aaaa::1 (aaaa::1) 990 Destination: aaaa::ff:fe00:1 (aaaa::ff:fe00:1) 991 Internet Control Message Protocol v6 992 Type: Echo (ping) request (128) 993 Code: 0 994 Checksum: 0x783f [correct] 995 Identifier: 0x2ee5 996 Sequence: 2 997 [Response In: 5165] 998 Data (510 bytes) 999 Data: e4dbe8553ba0040008090a0b0c0d0e0f1011121314151617... 1000 [Length: 510] 1002 Frame (547 bytes): 1003 55 ff 22 01 02 02 19 1c 56 2d 83 56 6f 6a 54 54 U.".....V-.VojTT 1004 54 54 54 54 57 54 56 54 d5 50 2d 6a 7b b0 5c 57 TTTTWTVT.P-j{.\W 1005 b1 8e bd 00 6e f5 51 ac 5d 5c 5f 5e 59 58 5b 5a ....n.Q.]\_^YX[Z 1006 45 44 47 46 41 40 43 42 4d 4c 4f 4e 49 48 4b 4a EDGFA@CBMLONIHKJ 1007 75 74 77 76 71 70 73 72 7d 7c 7f 7e 79 78 7b 7a utwvqpsr}|.~yx{z 1008 65 64 67 66 61 60 63 62 6d 6c 6f 6e 69 68 6b 6a edgfa`cbmlonihkj 1009 15 14 17 16 11 10 13 12 1d 1c 1f 1e 19 18 1b 1a ................ 1010 05 04 07 06 01 00 03 02 0d 0c 0f 0e 09 08 0b 0a ................ 1011 35 34 37 36 31 30 33 32 3d 3c 3f 3e 39 38 3b 3a 54761032=98;: 1012 25 24 27 26 21 20 23 22 2d 2c 2f 2e 29 28 2b 2a %$'&! #"-,/.)(+* 1013 d5 d4 d7 d6 d1 d0 d3 d2 dd dc df de d9 d8 db da ................ 1014 c5 c4 c7 c6 c1 c0 c3 c2 cd cc cf ce c9 c8 cb ca ................ 1015 f5 f4 f7 f6 f1 f0 f3 f2 fd fc ff fe f9 f8 fb fa ................ 1016 e5 e4 e7 e6 e1 e0 e3 e2 ed ec ef ee e9 e8 eb ea ................ 1017 95 94 97 96 91 90 93 92 9d 9c 9f 9e 99 98 9b 9a ................ 1018 85 84 87 86 81 80 83 82 8d 8c 8f 8e 89 88 8b 8a ................ 1019 b5 b4 b7 b6 b1 b0 b3 b2 bd bc bf be b9 b8 bb ba ................ 1020 a5 a4 a7 a6 a1 a0 a3 a2 ad ac af ae a9 a8 ab aa ................ 1021 ab 54 57 56 51 50 53 52 5d 5c 5f 5e 59 58 5b 5a .TWVQPSR]\_^YX[Z 1022 45 44 47 46 41 40 43 42 4d 4c 4f 4e 49 48 4b 4a EDGFA@CBMLONIHKJ 1023 75 74 77 76 71 70 73 72 7d 7c 7f 7e 79 78 7b 7a utwvqpsr}|.~yx{z 1024 65 64 67 66 61 60 63 62 6d 6c 6f 6e 69 68 6b 6a edgfa`cbmlonihkj 1025 15 14 17 16 11 10 13 12 1d 1c 1f 1e 19 18 1b 1a ................ 1026 05 04 07 06 01 00 03 02 0d 0c 0f 0e 09 08 0b 0a ................ 1027 35 34 37 36 31 30 33 32 3d 3c 3f 3e 39 38 3b 3a 54761032=98;: 1028 25 24 27 26 21 20 23 22 2d 2c 2f 2e 29 28 2b 2a %$'&! #"-,/.)(+* 1029 d5 d4 d7 d6 d1 d0 d3 d2 dd dc df de d9 d8 db da ................ 1030 c5 c4 c7 c6 c1 c0 c3 c2 cd cc cf ce c9 c8 cb ca ................ 1031 f5 f4 f7 f6 f1 f0 f3 f2 fd fc ff fe f9 f8 fb fa ................ 1032 e5 e4 e7 e6 e1 e0 e3 e2 ed ec ef ee e9 e8 eb ea ................ 1033 95 94 97 96 91 90 93 92 9d 9c 9f 9e 99 98 9b 9a ................ 1034 85 84 87 86 81 80 83 82 8d 8c 8f 8e 89 88 8b 8a ................ 1035 b5 b4 b7 b6 b1 b0 b3 b2 bd bc bf be b9 b8 bb ba ................ 1036 a5 a4 a7 a6 a1 a0 a3 a2 ad ac af ae a9 a8 50 cb ..............P. 1037 27 0c b7 '.. 1039 Decoded Data and CRC32K (537 bytes): 1040 78 d6 00 3a 3f 00 00 00 00 00 00 00 01 00 01 80 x..:?........... 1041 00 78 3f 2e e5 00 02 e4 db e8 55 3b a0 04 00 08 .x?.......U;.... 1042 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 ................ 1043 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 ....... !"#$%&'( 1044 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 )*+,-./012345678 1045 39 3a 3b 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 9:;<=>?@ABCDEFGH 1046 49 4a 4b 4c 4d 4e 4f 50 51 52 53 54 55 56 57 58 IJKLMNOPQRSTUVWX 1047 59 5a 5b 5c 5d 5e 5f 60 61 62 63 64 65 66 67 68 YZ[\]^_`abcdefgh 1048 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 75 76 77 78 ijklmnopqrstuvwx 1049 79 7a 7b 7c 7d 7e 7f 80 81 82 83 84 85 86 87 88 yz{|}~.......... 1050 89 8a 8b 8c 8d 8e 8f 90 91 92 93 94 95 96 97 98 ................ 1051 99 9a 9b 9c 9d 9e 9f a0 a1 a2 a3 a4 a5 a6 a7 a8 ................ 1052 a9 aa ab ac ad ae af b0 b1 b2 b3 b4 b5 b6 b7 b8 ................ 1053 b9 ba bb bc bd be bf c0 c1 c2 c3 c4 c5 c6 c7 c8 ................ 1054 c9 ca cb cc cd ce cf d0 d1 d2 d3 d4 d5 d6 d7 d8 ................ 1055 d9 da db dc dd de df e0 e1 e2 e3 e4 e5 e6 e7 e8 ................ 1056 e9 ea eb ec ed ee ef f0 f1 f2 f3 f4 f5 f6 f7 f8 ................ 1057 f9 fa fb fc fd fe ff 00 01 02 03 04 05 06 07 08 ................ 1058 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 ................ 1059 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 ....... !"#$%&'( 1060 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 )*+,-./012345678 1061 39 3a 3b 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 9:;<=>?@ABCDEFGH 1062 49 4a 4b 4c 4d 4e 4f 50 51 52 53 54 55 56 57 58 IJKLMNOPQRSTUVWX 1063 59 5a 5b 5c 5d 5e 5f 60 61 62 63 64 65 66 67 68 YZ[\]^_`abcdefgh 1064 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 75 76 77 78 ijklmnopqrstuvwx 1065 79 7a 7b 7c 7d 7e 7f 80 81 82 83 84 85 86 87 88 yz{|}~.......... 1066 89 8a 8b 8c 8d 8e 8f 90 91 92 93 94 95 96 97 98 ................ 1067 99 9a 9b 9c 9d 9e 9f a0 a1 a2 a3 a4 a5 a6 a7 a8 ................ 1068 a9 aa ab ac ad ae af b0 b1 b2 b3 b4 b5 b6 b7 b8 ................ 1069 b9 ba bb bc bd be bf c0 c1 c2 c3 c4 c5 c6 c7 c8 ................ 1070 c9 ca cb cc cd ce cf d0 d1 d2 d3 d4 d5 d6 d7 d8 ................ 1071 d9 da db dc dd de df e0 e1 e2 e3 e4 e5 e6 e7 e8 ................ 1072 e9 ea eb ec ed ee ef f0 f1 f2 f3 f4 f5 f6 f7 f8 ................ 1073 f9 fa fb fc fd 9e 72 59 e2 ......rY. 1075 Decompressed 6LoWPAN IPHC (558 bytes): 1076 60 00 00 00 02 06 3a 3f aa aa 00 00 00 00 00 00 `.....:?........ 1077 00 00 00 00 00 00 00 01 aa aa 00 00 00 00 00 00 ................ 1078 00 00 00 ff fe 00 00 01 80 00 78 3f 2e e5 00 02 ..........x?.... 1079 e4 db e8 55 3b a0 04 00 08 09 0a 0b 0c 0d 0e 0f ...U;........... 1080 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................ 1081 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f !"#$%&'()*+,-./ 1082 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 0123456789:;<=>? 1083 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO 1084 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f PQRSTUVWXYZ[\]^_ 1085 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f `abcdefghijklmno 1086 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f pqrstuvwxyz{|}~. 1087 80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f ................ 1088 90 91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f ................ 1089 a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af ................ 1090 b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf ................ 1091 c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf ................ 1092 d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df ................ 1093 e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef ................ 1094 f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff ................ 1095 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................ 1096 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................ 1097 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f !"#$%&'()*+,-./ 1098 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 0123456789:;<=>? 1099 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO 1100 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f PQRSTUVWXYZ[\]^_ 1101 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f `abcdefghijklmno 1102 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f pqrstuvwxyz{|}~. 1103 80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f ................ 1104 90 91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f ................ 1105 a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af ................ 1106 b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf ................ 1107 c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf ................ 1108 d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df ................ 1109 e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef ................ 1110 f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd .............. 1112 Authors' Addresses 1114 Kerry Lynn (editor) 1115 Verizon Labs 1116 50 Sylvan Rd 1117 Waltham , MA 02451 1118 USA 1120 Phone: +1 781 296 9722 1121 Email: kerlyn@ieee.org 1123 Jerry Martocci 1124 Johnson Controls, Inc. 1125 507 E. Michigan St 1126 Milwaukee , WI 53202 1127 USA 1129 Phone: +1 414 524 4010 1130 Email: jerald.p.martocci@jci.com 1132 Carl Neilson 1133 Delta Controls, Inc. 1134 17850 56th Ave 1135 Surrey , BC V3S 1C7 1136 Canada 1138 Phone: +1 604 575 5913 1139 Email: cneilson@deltacontrols.com 1141 Stuart Donaldson 1142 Honeywell Automation & Control Solutions 1143 6670 185th Ave NE 1144 Redmond , WA 98052 1145 USA 1147 Email: stuart.donaldson@honeywell.com