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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 4, 2008) is 5747 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Networking Working Group A. Brandt 2 Internet Draft Zensys, Inc. 3 Intended status: Informational G. Porcu 4 Expires: January 2009 Telecom Italia 5 July 4, 2008 7 Home Automation Routing Requirement in Low Power and Lossy Networks 8 draft-ietf-roll-home-routing-reqs-01 10 Status of this Memo 12 By submitting this Internet-Draft, each author represents that 13 any applicable patent or other IPR claims of which he or she is 14 aware have been or will be disclosed, and any of which he or she 15 becomes aware will be disclosed, in accordance with Section 6 of 16 BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that other 20 groups may also distribute working documents as Internet-Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html 33 This Internet-Draft will expire on January 4, 2009. 35 Copyright Notice 37 Copyright (C) The IETF Trust (2008). 39 Abstract 41 This document presents home control and automation application 42 specific requirements for ROuting in Low power and Lossy networks 43 (ROLL). In a modern home, a high number of wireless devices are used 44 for a wide set of purposes. Examples include lighting control, 45 heating control, sensors, leak detectors, healthcare systems and 46 advanced remote controls. Because such devices only cover a limited 47 radio range, multi-hop routing is often required. The aim of this 48 document is to specify the routing requirements for networks 49 comprising such constrained devices in a home network environment. 51 Requirements Language 53 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 54 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 55 document are to be interpreted as described in RFC-2119 [RFC2119]. 57 Table of Contents 59 1. Terminology....................................................3 60 2. Introduction...................................................3 61 3. Home automation applications...................................4 62 3.1. Turning off the house when leaving........................4 63 3.2. Energy conservation and optimizing energy consumption.....5 64 3.3. Moving a remote control around............................5 65 3.4. Adding a new lamp module to the system....................6 66 3.5. Controlling battery operated window shades................6 67 3.6. Remote video surveillance.................................6 68 3.7. Healthcare................................................6 69 3.7.1. At-home health reporting.............................7 70 3.7.2. At-home health monitoring............................7 71 3.7.3. Healthcare routing considerations....................8 72 3.8. Alarm systems.............................................8 73 3.9. Battery-powered devices...................................9 74 4. Unique requirements of home automation applications............9 75 4.1. Support of groupcast......................................9 76 4.2. Constraint-based Routing..................................9 77 4.3. Support of Mobility......................................10 78 4.4. Support of Periodical Scanning...........................10 79 4.5. Scalability..............................................11 80 4.6. Convergence Time.........................................11 81 4.7. Manageability............................................11 82 5. Traffic Pattern...............................................11 83 6. Open issues...................................................12 84 7. Security Considerations.......................................12 85 8. IANA Considerations...........................................13 86 9. Acknowledgments...............................................13 87 10. References...................................................13 88 10.1. Normative References....................................13 89 10.2. Informative References..................................14 90 Disclaimer of Validity...........................................15 92 1. Terminology 94 ROLL: ROuting in Low-power and Lossy networks 96 ROLL device: A ROLL network node with constrained CPU and memory 97 resources; potentially constrained power resources. 99 Access Point: The access point is an infrastructure device that 100 connects the low power and lossy network system to the 101 Internet, possibly via a customer premises local area 102 network (LAN). 104 LAN: Local Area Network. 106 PAN: Personal Area Network. 107 A geographically limited wireless network based on 108 e.g. 802.15.4 or Z-Wave radio. 110 Channel: Radio frequency band used to transmit a modulated 111 signal carrying packets. 113 Downstream: Data direction traveling from a Local Area Network 114 (LAN) to a Personal Area Network (PAN) device. 116 Upstream: Data direction traveling from a PAN to a LAN device. 118 Sensor: A PAN device that measures data and/or detects an 119 event. 121 2. Introduction 123 This document presents the home control and automation application 124 specific requirements for Routing in Low power and Lossy Networks 125 (ROLL). In a modern home, a high number of wireless devices are used 126 for a wide set of purposes. Examples include lighting control 127 modules, heating control panels, light sensors, temperature sensors, 128 gas/water leak detectors, motion detectors, video surveillance, 129 healthcare systems and advanced remote controls. Basic home control 130 modules such as wall switches and plug-in modules may be turned into 131 an advanced home automation solution via the use of an IP-enabled 132 application responding to events generated by wall switches, motion 133 sensors, light sensors, rain sensors, and so on. 135 Because such devices only cover a limited radio range, multi-hop 136 routing is often required. These devices are usually highly 137 constrained in term of resources such as battery and memory and 138 operate in unstable environments. Persons moving around in a house, 139 opening or closing a door or starting a microwave oven affect the 140 reception of weak radio signals. Reflection and absorption may cause 141 a reliable radio link to turn unreliable for a period of time and 142 then being reusable again, thus the term "lossy". 144 Unlike other categories of PANs, the connected home area is very much 145 consumer-oriented. The implications on network nodes in this aspect, 146 is that devices are very cost sensitive, which leads to resource- 147 constrained environments having slow CPUs and small memory 148 footprints. At the same time, nodes have to be physically small which 149 puts a limit to the physical size of the battery; and thus, the 150 battery capacity. As a result, it is common for low-power sensor- 151 style nodes to shut down radio and CPU resources for most of the 152 time. Often, the radio uses the same power for listening as for 153 transmitting. 155 Section 3. describes a few typical use cases for home automation 156 applications. Section 4. discusses the routing requirements for 157 networks comprising such constrained devices in a home network 158 environment. These requirements may be overlapping requirements 159 derived from other application-specific requirements. 161 3. Home automation applications 163 Home automation applications represent a special segment of networked 164 wireless devices with its unique set of requirements. To facilitate 165 the requirements discussion in Section 4, this section lists a few 166 typical use cases of home automation applications. New applications 167 are being developed at a high pace and this section does not mean to 168 be exhaustive. Most home automation applications tend to be running 169 some kind of command/response protocol. The command may come from 170 several places. For instance a lamp may be turned on, not only be a 171 wall switch but also from a movement sensor. 173 3.1. Turning off the house when leaving 175 Using the direct analogy to an electronic car key, a house owner may 176 activate the "leaving home" function from an electronic house key, 177 mobile phone, etc. For the sake of visual impression, all lights 178 should turn off at the same time. At least, it should appear to 179 happen at the same time. A well-known problem in wireless home 180 automation is the "popcorn effect": Lamps are turned on one at a 181 time, at a rate so slow that it is clearly visible. Some existing 182 home automation solutions use a clever mix of a "subnet groupcast" 183 message with no acknowledgement and no forwarding before sending 184 acknowledged singlecast messages to each lighting device. 186 The controller forms the groups and decides which nodes should 187 receive "turn-off" or "turn-on" requests. 189 3.2. Energy conservation and optimizing energy consumption 191 Parts of the world using air conditioning may let shades go down and 192 turn off the AC device when leaving home. Air conditioning may start 193 by timer or via motion sensor when the owner returns home. The owner 194 may even activate the air conditioning via cell phone before getting 195 home. 197 Geographical areas using central heating may turn off heating when 198 not at home and use a reduced temperature during night time. 200 The power grid may experience periods where more wind-generated power 201 is produced than is needed. Typically this may happen during night 202 hours. The washing machine and dish washer may just as well work 203 while power is cheap. The electric car should also charge its 204 batteries on cheap power. 206 In periods where electricity demands exceed available supply, 207 appliances such as air conditioning, climate control systems, washing 208 machines etc. can be turned off to avoid overloading the power grid. 209 Wireless remote control of the household appliances is well-suited 210 for this application. The start/stop decision for the appliances can 211 be regulated by dynamic power pricing information obtained from the 212 electricity utility companies. 214 Most of these applications are mains powered and are thus ideal for 215 providing reliable, always-on routing resources. Battery-powered 216 nodes, by comparison, are constrained routing resources and may only 217 provide reliable routing under some circumstances. 219 3.3. Moving a remote control around 221 A remote control is a typical example of a mobile device in a home 222 automation network. An advanced remote control may be used for 223 dimming the light in the dining room while eating and later on, 224 turning up the music while doing the dishes in the kitchen. Reaction 225 must appear to be instant (within a few hundred milliseconds) even 226 when the remote control has moved to a new location. The remote 227 control may be communicating to either a central home automation 228 controller or directly to the lamps and the media center. 230 3.4. Adding a new lamp module to the system 232 Small-size, low-cost modules may have no user interface except for a 233 single button. Thus, an automated inclusion process is needed for 234 controllers to find new modules. Inclusion covers the detection of 235 neighbors and assignment of a unique node ID. Inclusion should be 236 completed within a few seconds. 238 Distribution of unique addresses is usually performed by a central 239 controller. In this case, it must be possible to route the inclusion 240 request from the joining node to the central controller even before 241 the joining node is assigned a unique address. 243 3.5. Controlling battery operated window shades 245 In consumer premises, window shades are often battery-powered as 246 there is no access to mains power over the windows. For battery 247 conservation purposes, the receiver is sleeping most of the time. A 248 home automation controller sending commands to window shades via ROLL 249 devices will have no problems delivering the packet to the router, 250 but the router may have to wait for some time before the command can 251 be delivered to the window shades if the receiver is sleeping; e.g. 252 up to 250ms. 254 3.6. Remote video surveillance 256 Remote video surveillance is a fairly classic application for Home 257 networking providing the ability for the end user to get a video 258 stream from a Web Cam reached via the Internet, which can be 259 triggered by the end-user that has received an alarm from a movement 260 sensor or smoke detector - or the user simply wants to check the home 261 status via video. 262 Note that in the former case, more than likely, there will be a form 263 of inter-device communication: indeed, upon detecting some movement 264 in the home, the movement sensor may send a request to the light 265 controller to turn-on the lights, to the Web Cam to start a video 266 stream that would then be directed to the end user (cell phone, PDA) 267 via the Internet. 268 By contrast with other applications, e.g. industrial sensors where 269 data would mainly be originated by sensor to a sink and vice versa, 270 this scenario implicates a direct inter-device communication between 271 ROLL devices. 273 3.7. Healthcare 275 By adding communication capability to devices, patients and elderly 276 citizens may be able to do simple measurements at home. Thanks to 277 online devices, a doctor can keep an eye on the patient's health and 278 receive warnings if a new trend is discovered by automated filters. 280 Fine-grained daily measurements presented in proper ways may allow 281 the doctor to establish a more precise diagnosis. 283 Such applications may be realized as wearable products which 284 frequently do a measurement and automatically deliver the result to a 285 data sink locally or over the Internet. 287 Applications falling in this category are referred to as at-home 288 health reporting. Whether measurements are done in a fixed interval 289 or if they are manually activated, they leave all processing to the 290 receiving data sink. 292 A more active category of applications may send an alarm if some 293 alarm condition is triggered. This category of applications is 294 referred to as at-home health monitoring. Measurements are 295 interpreted in the device and may cause reporting of an event if an 296 alarm is triggered. 298 Many implementations may overlap both categories. 300 3.7.1. At-home health reporting 302 Applications might include: 304 o Temperature 306 o Weight 308 o Blood pressure 310 o Insulin level 312 Measurements may be stored for long term statistics. At the same 313 time, a critically high blood pressure may cause the generation of an 314 alarm report. Refer to 3.7.2. 316 To avoid a high number of request messages, nodes may be configured 317 to autonomously do a measurement and send a report in intervals. 319 3.7.2. At-home health monitoring 321 An alarm event may become active e.g. if the measured blood pressure 322 exceeds a threshold or if a person falls to the ground. 324 Applications might include: 326 o Temperature 328 o Weight 330 o Blood pressure 332 o Insulin level 334 o Electrocardiogram (ECG) 336 o Position tracker 338 3.7.3. Healthcare routing considerations 340 From a ROLL perspective, all the above-mentioned applications may run 341 on battery. They may also be portable and therefore need to locate a 342 new neighbor router on a frequent basis. 343 Not being powered most of the time, the nodes should not be used as 344 routing nodes. However, sleeping, battery-powered nodes may be 345 involved in routing. Examples include cases where a person falls 346 during a power blackout. In that case it may be that no mains-powered 347 routers are available for forwarding the alarm message to a (battery- 348 backed) internet gateway located out of direct range. 350 Delivery of measurement data has a more relaxed requirement for route 351 discovery time compared to a remote control. On the other hand, it is 352 critical that a "person fell" alarm is actually delivered in the end. 354 3.8. Alarm systems 356 A home security alarm system is comprised of various devices like 357 vibration detectors, fire or carbon monoxide detection system, door 358 or window contacts, glass-break detector, presence sensor, panic 359 button, home security key. 361 Some smoke alarms are battery powered and at the same time mounted in 362 a high place. Battery-powered safety devices should only be used for 363 routing if no other alternatives exist. A smoke alarm with a drained 364 battery does not provide a lot of safety. Also, it may be 365 inconvenient to exchange battery in a smoke alarm. Finally, routing 366 via battery-powered nodes may be very slow if they are sleeping most 367 of the time. 368 All of the above-mentioned reasons suggest that routing should be 369 avoided via this category of devices. 371 A plethora of applications could be developed for home alarm system: 372 most of them, most of the time, have prevention and monitoring 373 activity in which routing requirements are deterministic, but all of 374 them have an alarm state in which nodes may burst an aperiodic alarm. 376 3.9. Battery-powered devices 378 For convenience and low operational costs, power consumption of 379 consumer products must be kept at a very low level to achieve a long 380 battery lifetime. One implication of this fact is that RAM memory is 381 limited and it may even be powered down; leaving only a few 100 bytes 382 of RAM alive during the sleep phase. 384 4. Unique requirements of home automation applications 386 Home automation applications have a number of specific requirements 387 related to the set of home networking applications and the perceived 388 operation of the system. 390 4.1. Support of groupcast 392 Groupcast, in the context of home automation, is defined as the 393 ability to simultaneously transmit a message to a group of recipients 394 without prior interaction with the group members (i.e. group setup). 395 A use-case for groupcast is given in Section 3.1. 397 Broadcast and groupcast in home automation MAY be used to deliver the 398 illusion that all recipients respond simultaneously. Distant 399 recipients out of direct range may not react to the (unacknowledged) 400 groupcast. Acknowledged unicast delivery MUST be used subsequently. 402 The support of unicast, groupcast and broadcast also has an 403 implication on the addressing scheme and are outside the scope of 404 this document that focuses on the routing requirements aspects. 406 It MUST be to possible to address a group of receivers known by the 407 sender even if the receivers do not know that they have been grouped 408 by the sender. 410 4.2. Constraint-based Routing 412 Simple battery-powered nodes such as movement sensors on garage doors 413 and rain meters may not be able to assist in routing. Depending on 414 the node type, the node never listens at all, listens rarely or makes 415 contact on demand to a pre-configured target node. Attempting to 416 communicate to such nodes may require long time before getting a 417 response. 419 Other battery-powered nodes may have the capability to participate in 420 routing. The routing protocol should either share the load between 421 nodes to preserve battery or only route via mains-powered nodes if 422 possible. The most reliable routing resource may be a battery-backed, 423 mains-powered smoke alarm. 425 The routing protocol MUST support constraint-based routing taking 426 into account node properties (CPU, memory, level of energy, sleep 427 intervals, safety/convenience of changing battery). 429 4.3. Support of Mobility 431 In a home environment, although the majority of devices are fixed 432 devices, there is still a variety of mobile devices: for example a 433 multi-purpose remote control is likely to move. Another example of 434 mobile devices is wearable healthcare devices. 436 While healthcare devices delivering measurement results can tolerate 437 route discovery times measured in seconds, a remote control appears 438 unresponsive if using more than 0.5 seconds to e.g. pause the music. 440 While, in theory, all battery-powered devices and mains-powered plug- 441 in modules may be moved, the predominant case is that the sending 442 node has moved while the rest of the network has not changed. 444 The routing protocol MUST provide mobility with convergence time 445 below 0.5 second if only the sender has moved. 447 A non-responsive node can either be caused by 1) a failure in the 448 node, 2) a failed link on the path to the node or 3) a moved node. In 449 the first two cases, the node can be expected to reappear at roughly 450 the same location in the network, whereas it can return anywhere in 451 the network in the latter case. The search strategy in the routing 452 protocol will behave differently depending on this expectation. The 453 routing protocol SHOULD make use of the fact that if not being able 454 to deliver a packet, it is most likely that the sending node moved; 455 rather than a failure occurred in that node or in a link on the path 456 towards it. 458 4.4. Support of Periodical Scanning 460 The routing protocol MUST support the recognition of neighbors and 461 periodical scanning. This process SHOULD preserve energy capacity as 462 much as possible. 464 (Derived from use case 3.8. Alarm Systems) 466 4.5. Scalability 468 Looking at the number of wall switches, power outlets, sensors of 469 various nature, video equipment and so on in a modern house, it seems 470 quite realistic that hundreds of low power devices may form a home 471 automation network in a fully populated "smart" home. Moving towards 472 professional building automation, the number of such devices may be 473 in the order of several thousands. 475 Thus, the routing protocol MUST support 250 devices in a subnet. 476 The routing protocol SHOULD support 2500 devices in a subnet. 478 4.6. Convergence Time 480 A home automation Personal Area Network (PAN) is subject to various 481 instability due to signal strength variation, moving persons and the 482 like. Furthermore, as the number of devices increases, the 483 probability of a node failure also increases. 485 Measured from the transmission of a packet, the following convergence 486 time requirements apply. 488 The routing protocol MUST converge within 0.5 second if no nodes have 489 moved. 491 The routing protocol MUST converge within 2 seconds if the 492 destination node of the packet has moved. 494 4.7. Manageability 496 The ability of the home network to support auto-configuration is of 497 the utmost importance. Indeed, most end users will not have the 498 expertise and the skills to perform advanced configuration and 499 troubleshooting. Thus the routing protocol designed for home PAN MUST 500 provide a set of features including zero-configuration of the routing 501 protocol for a new node to be added to the network. From ROLL 502 perspective, zero-configuration means that a node can obtain an 503 address and join the network on its own, without human intervention. 505 The routing protocol MUST support the ability to isolate a 506 misbehaving node thus preserving the correct operation of overall 507 network. 509 5. Traffic Pattern 511 Depending on the philosophy of the home network, wall switches may be 512 configured to directly control individual lamps or alternatively, all 513 wall switches send control commands to a central lighting control 514 computer which again sends out control commands to relevant devices. 516 In a distributed system, the traffic tends to be any-to-many. In a 517 centralized system, it is a mix of any-to-one and one-to-many. 519 Wall switches only generate traffic when activated, which typically 520 happens from a one to tens of times per hour. 522 Remote controls have a similar transmit pattern to wall switches, but 523 are activated more frequently. 525 Temperature/air pressure/rain sensors send frames when queried by the 526 user or can be preconfigured to send measurements at fixed intervals 527 (typically minutes). Motion sensors typically send a frame when 528 motion is first detected and another frame when an idle period with 529 no movement has elapsed. The highest transmission frequency depends 530 on the idle period used in the sensor. Sometimes, a timer will 531 trigger a frame transmission when an extended period without status 532 change has elapsed. 534 All frames sent in the above examples are quite short, typically less 535 than 5 bytes of payload. Lost frames and interference from other 536 transmitters may lead to retransmissions. In all cases, 537 acknowledgment frames with a size of a few bytes are used. 539 6. Open issues 541 Other items to be addressed in further revisions of this document 542 include: 544 o Load Balancing (Symmetrical and Asymmetrical) 546 o Security 548 7. Security Considerations 550 Encryption can be employed to provide confidentiality, integrity and 551 authentication of the messages carried on the wireless links. Adding 552 these capabilities to the ROLL devices will degrade energy efficiency 553 and increase cost, so a trade-off must be made for each specific 554 application. 556 Door locks, alarm sensors and medication dosage equipment are 557 examples where strong encryption and authentication are needed. The 558 command to unlock a door must be authenticated, as must the 559 communication between an alarm sensor and the central alarm 560 controller. Furthermore, traffic analysis of the alarm system 561 communication must not reveal if the alarm is activated. 563 Light dimmers, window shades, motion sensors, weight sensors etc. may 564 not need encryption. 566 Protection against unintentional inclusion in neighboring networks 567 must be provided. Providing confidentiality, integrity and 568 authentication against malicious opponents is optional. 570 8. IANA Considerations 572 This document includes no request to IANA. 574 9. Acknowledgments 576 J. P. Vasseur, Jonathan Hui, Eunsook "Eunah" Kim and Mischa Dohler 577 are gratefully acknowledged for their contributions to this document. 579 This document was prepared using 2-Word-v2.0.template.dot. 581 10. References 583 10.1. Normative References 585 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 586 Requirement Levels", BCP 14, RFC 2119, March 1997. 588 10.2. Informative References 590 Author's Addresses 592 Anders Brandt 593 Zensys, Inc. 594 Emdrupvej 26 595 Copenhagen, DK-2100 596 Denmark 598 Email: abr@zen-sys.com 600 Giorgio Porcu 601 Telecom Italia 602 Piazza degli Affari, 2 603 20123 Milan 604 Italy 606 Email: giorgio.porcu@telecomitalia.it 608 Intellectual Property Statement 610 The IETF takes no position regarding the validity or scope of any 611 Intellectual Property Rights or other rights that might be claimed to 612 pertain to the implementation or use of the technology described in 613 this document or the extent to which any license under such rights 614 might or might not be available; nor does it represent that it has 615 made any independent effort to identify any such rights. Information 616 on the procedures with respect to rights in RFC documents can be 617 found in BCP 78 and BCP 79. 619 Copies of IPR disclosures made to the IETF Secretariat and any 620 assurances of licenses to be made available, or the result of an 621 attempt made to obtain a general license or permission for the use of 622 such proprietary rights by implementers or users of this 623 specification can be obtained from the IETF on-line IPR repository at 624 http://www.ietf.org/ipr. 626 The IETF invites any interested party to bring to its attention any 627 copyrights, patents or patent applications, or other proprietary 628 rights that may cover technology that may be required to implement 629 this standard. Please address the information to the IETF at 630 ietf-ipr@ietf.org. 632 Disclaimer of Validity 634 This document and the information contained herein are provided on an 635 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 636 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 637 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 638 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 639 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 640 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 642 Copyright Statement 644 Copyright (C) The IETF Trust (2008). 646 This document is subject to the rights, licenses and restrictions 647 contained in BCP 78, and except as set forth therein, the authors 648 retain all their rights. 650 Acknowledgment 652 Funding for the RFC Editor function is currently provided by the 653 Internet Society.