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Bagnulo 7 UC3M 8 T. Burbridge 9 BT 10 P. Aitken 11 A. Akhter 12 Cisco Systems 13 June 24, 2014 15 A framework for large-scale measurement platforms (LMAP) 16 draft-ietf-lmap-framework-07 18 Abstract 20 Measuring broadband service on a large scale requires a description 21 of the logical architecture and standardisation of the key protocols 22 that coordinate interactions between the components. The document 23 presents an overall framework for large-scale measurements. It also 24 defines terminology for LMAP (large-scale measurement platforms). 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on December 26, 2014. 43 Copyright Notice 45 Copyright (c) 2014 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. Outline of an LMAP-based measurement system . . . . . . . . . 5 62 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 8 63 4. Constraints . . . . . . . . . . . . . . . . . . . . . . . . . 11 64 4.1. Measurement system is under the direction of a single 65 organisation . . . . . . . . . . . . . . . . . . . . . . 11 66 4.2. Each MA may only have a single Controller at any point in 67 time . . . . . . . . . . . . . . . . . . . . . . . . . . 12 68 5. LMAP Protocol Model . . . . . . . . . . . . . . . . . . . . . 12 69 5.1. Bootstrapping process . . . . . . . . . . . . . . . . . . 13 70 5.2. Control Protocol . . . . . . . . . . . . . . . . . . . . 14 71 5.2.1. Configuration . . . . . . . . . . . . . . . . . . . . 14 72 5.2.2. Instruction . . . . . . . . . . . . . . . . . . . . . 15 73 5.2.3. Capabilities and Failure information . . . . . . . . 18 74 5.3. Operation of Measurement Tasks . . . . . . . . . . . . . 20 75 5.3.1. Starting and Stopping Measurement Tasks . . . . . . . 20 76 5.3.2. Overlapping Measurement Tasks . . . . . . . . . . . . 21 77 5.4. Report Protocol . . . . . . . . . . . . . . . . . . . . . 22 78 5.4.1. Reporting of Subscriber's service parameters . . . . 23 79 5.5. Operation of LMAP over the underlying packet transfer 80 mechanism . . . . . . . . . . . . . . . . . . . . . . . . 23 81 5.6. Items beyond the scope of the initial LMAP work . . . . . 24 82 5.6.1. End-user-controlled measurement system . . . . . . . 25 83 6. Deployment considerations . . . . . . . . . . . . . . . . . . 26 84 6.1. Controller and the measurement system . . . . . . . . . . 26 85 6.2. Measurement Agent . . . . . . . . . . . . . . . . . . . . 27 86 6.2.1. Measurement Agent on a networked device . . . . . . . 27 87 6.2.2. Measurement Agent embedded in site gateway . . . . . 27 88 6.2.3. Measurement Agent embedded behind site NAT /Firewall 28 89 6.2.4. Multi-homed Measurement Agent . . . . . . . . . . . . 28 90 6.2.5. Measurement Agent embedded in ISP Network . . . . . . 29 91 6.3. Measurement Peer . . . . . . . . . . . . . . . . . . . . 29 92 7. Security considerations . . . . . . . . . . . . . . . . . . . 29 93 8. Privacy Considerations for LMAP . . . . . . . . . . . . . . . 31 94 8.1. Categories of Entities with Information of Interest . . . 31 95 8.2. Examples of Sensitive Information . . . . . . . . . . . . 32 96 8.3. Different privacy issues raised by different sorts of 97 Measurement Methods . . . . . . . . . . . . . . . . . . . 33 98 8.4. Privacy analysis of the Communications Models . . . . . . 34 99 8.4.1. MA Bootstrapping . . . . . . . . . . . . . . . . . . 34 100 8.4.2. Controller <-> Measurement Agent . . . . . . . . . . 35 101 8.4.3. Collector <-> Measurement Agent . . . . . . . . . . . 36 102 8.4.4. Measurement Peer <-> Measurement Agent . . . . . . . 36 103 8.4.5. Measurement Agent . . . . . . . . . . . . . . . . . . 37 104 8.4.6. Storage and Reporting of Measurement Results . . . . 38 105 8.5. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 38 106 8.5.1. Surveillance . . . . . . . . . . . . . . . . . . . . 39 107 8.5.2. Stored Data Compromise . . . . . . . . . . . . . . . 39 108 8.5.3. Correlation and Identification . . . . . . . . . . . 40 109 8.5.4. Secondary Use and Disclosure . . . . . . . . . . . . 40 110 8.6. Mitigations . . . . . . . . . . . . . . . . . . . . . . . 40 111 8.6.1. Data Minimisation . . . . . . . . . . . . . . . . . . 41 112 8.6.2. Anonymity . . . . . . . . . . . . . . . . . . . . . . 41 113 8.6.3. Pseudonymity . . . . . . . . . . . . . . . . . . . . 42 114 8.6.4. Other Mitigations . . . . . . . . . . . . . . . . . . 43 115 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43 116 10. Appendix: Deployment examples . . . . . . . . . . . . . . . . 44 117 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 47 118 12. History . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 119 12.1. From -00 to -01 . . . . . . . . . . . . . . . . . . . . 48 120 12.2. From -01 to -02 . . . . . . . . . . . . . . . . . . . . 48 121 12.3. From -02 to -03 . . . . . . . . . . . . . . . . . . . . 49 122 12.4. From -03 to -04 . . . . . . . . . . . . . . . . . . . . 50 123 12.5. From -04 to -05 . . . . . . . . . . . . . . . . . . . . 50 124 12.6. From -05 to -06 . . . . . . . . . . . . . . . . . . . . 51 125 12.7. From -06 to -07 . . . . . . . . . . . . . . . . . . . . 51 126 13. Informative References . . . . . . . . . . . . . . . . . . . 52 127 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53 129 1. Introduction 131 There is a desire to be able to coordinate the execution of broadband 132 measurements and the collection of measurement results across a large 133 scale set of diverse devices. These devices could be software based 134 agents on PCs, embedded agents in consumer devices (e.g. Blu-ray 135 players), service provider controlled devices such as set-top boxes 136 and home gateways, or simply dedicated probes. It is expected that 137 such a system could easily comprise 100,000 devices. Measurement 138 devices may also be embedded on a device that is part of an ISP's 139 network, such as a DSLAM, router, Carrier Grade NAT or ISP Gateway. 140 Such a scale presents unique problems in coordination, execution and 141 measurement result collection. Several use cases have been proposed 142 for large-scale measurements including: 144 o Operators: to help plan their network and identify faults 146 o Regulators: to benchmark several network operators and support 147 public policy development 149 Further details of the use cases can be found in 150 [I-D.ietf-lmap-use-cases]. The LMAP framework should be useful for 151 these, as well as other use cases, such as to help end users run 152 diagnostic checks like a network speed test. 154 The LMAP Framework has three basic elements: Measurement Agents, 155 Controllers and Collectors. 157 Measurement Agents (MAs) initiate the actual measurements, which are 158 called Measurement Tasks in the LMAP terminology. In principle, 159 there are no restrictions on the type of device in which the MA 160 function resides. 162 The Controller instructs one or more MAs and communicates the set of 163 Measurement Tasks an MA should perform and when. For example it may 164 instruct a MA at a home gateway: "Measure the 'UDP latency' with 165 www.example.org; repeat every hour at xx.05". The Controller also 166 manages a MA by instructing it how to report the Measurement Results, 167 for example: "Report results once a day in a batch at 4am". We refer 168 to these as the Measurement Schedule and Report Schedule. 170 The Collector accepts Reports from the MAs with the Results from 171 their Measurement Tasks. Therefore the MA is a device that gets 172 Instructions from the Controller, initiates the Measurement Tasks, 173 and reports to the Collector. The communications between these three 174 LMAP functions are structured according to a Control Protocol and a 175 Report Protocol. 177 The desirable features for a large-scale measurement systems we are 178 designing for are: 180 o Standardised - in terms of the Measurement Tasks that they 181 perform, the components, the data models and protocols for 182 transferring information between the components. Amongst other 183 things, standardisation enables meaningful comparisons of 184 measurements made of the same metric at different times and 185 places, and provides the operator of a measurement system with 186 criteria for evaluation of the different solutions that can be 187 used for various purposes including buying decisions (such as 188 buying the various components from different vendors). Today's 189 systems are proprietary in some or all of these aspects. 191 o Large-scale - [I-D.ietf-lmap-use-cases] envisages Measurement 192 Agents in every home gateway and edge device such as set-top boxes 193 and tablet computers, and located throughout the Internet as well 194 [I-D.ietf-ippm-lmap-path]. It is expected that a measurement 195 system could easily encompass a few hundred thousand or even 196 millions of Measurement Agents. Existing systems have up to a few 197 thousand MAs (without judging how much further they could scale). 199 o Diversity - a measurement system should handle different types of 200 Measurement Agents - for example Measurement Agents may come from 201 different vendors, be in wired and wireless networks, be able to 202 execute different sorts of Measurement Task and be on devices with 203 IPv4 or IPv6 addresses. 205 2. Outline of an LMAP-based measurement system 207 Figure 1 shows the main components of a measurement system, and the 208 interactions of those components. Some of the components are outside 209 the scope of initial LMAP work. In this section we provide an 210 overview of the whole measurement system and we introduce the main 211 terms needed for the LMAP framework. The new terms are capitalised. 212 In the next section we provide a terminology section with a 213 compilation of all the LMAP terms and their definition. Section 4 214 onwards considers the LMAP components in more detail. 216 Other LMAP specifications will define an information model, the 217 associated data models, and select/extend one or more protocols for 218 the secure communication: firstly, a Control Protocol, from a 219 Controller to instruct Measurement Agents what performance metrics to 220 measure, when to measure them, how/when to report the measurement 221 results to a Collector; secondly, a Report Protocol, for a 222 Measurement Agent to report the results to the Collector. 224 The MA performs Measurement Tasks. The MAs are pieces of code that 225 can be executed in specialised hardware (hardware probe) or on a 226 general-purpose device (like a PC or mobile phone). The MA may 227 generate Measurement Traffic and measure some metric associated with 228 its transfer, or the MA may observe existing traffic, or there may be 229 some kind of hybrid of these two possibilities. A device with a 230 Measurement Agent may have multiple physical interfaces (Wi-Fi, 231 Ethernet, DSL, fibre; and non-physical interfaces such as PPPoE or 232 IPsec) and the Measurement Tasks may specify any one of these. 234 The Controller manages a MA through use of the Control Protocol, 235 which transfers the Instruction to the MA. This describes the 236 Measurement Tasks the MA should perform and when. For example the 237 Controller may instruct a MA at a home gateway: "Count the number of 238 TCP SYN packets observed in a 1 minute interval; repeat every hour at 239 xx.05 + Unif[0,180] seconds". The Measurement Schedule determines 240 when the Measurement Tasks are executed. The Controller also manages 241 a MA by instructing it how to report the Measurement Results, for 242 example: "Report results once a day in a batch at 4am + Unif[0,180] 243 seconds; if the end user is active then delay the report 5 minutes". 244 The Report Schedule determines when the Reports are uploaded to the 245 Collector. The Measurement Schedule and Report Schedule can define 246 one-off (non-recurring) actions ("Do measurement now", "Report as 247 soon as possible"), as well as recurring ones. 249 The Collector accepts a Report from a MA with the Measurement Results 250 from its Measurement Tasks. It then provides the Results to a 251 repository (see below). 253 A Measurement Method defines how to measure a Metric of interest. It 254 is very useful to standardise Measurement Methods, so that it is 255 meaningful to compare measurements of the same Metric made at 256 different times and places. It is also useful to define a registry 257 for commonly-used Metrics [I-D.manyfolks-ippm-metric-registry] so 258 that a Metric with its associated Measurement Method can be referred 259 to simply by its identifier in the registry. The Measurement Methods 260 and registry will hopefully be referenced by other standards 261 organisations. 263 Broadly speaking there are two types of Measurement Method. It may 264 involve a single MA simply observing existing traffic - for example, 265 the Measurement Agent could count bytes or calculate the average loss 266 for a particular flow. On the other hand, a Measurement Method may 267 involve multiple network entities, which perform different roles. 268 For example, a "ping" Measurement Method, to measure the round trip 269 delay , would consist of an MA sending an ICMP ECHO request to a 270 responder in the Internet. In LMAP terms, the responder is termed a 271 Measurement Peer (MP), meaning that it helps the MA but is not 272 managed by the Controller. Other Measurement Methods involve a 273 second MA, with the Controller instructing the MAs in a coordinated 274 manner. Traffic generated specifically as part of the Measurement 275 Method is termed Measurement Traffic; in the ping example, it is the 276 ICMP ECHO Requests and Replies. The protocols used for the 277 Measurement Traffic are out of the scope of initial LMAP work, and 278 fall within the scope of other IETF WGs such as IPPM. The 279 Appendix has some other examples of possible arrangements of 280 Measurement Agents and Peers. 282 A Measurement Task is the action performed by a particular MA at a 283 particular time, as the specific instance of its role in a 284 Measurement Method. LMAP is mainly concerned with Measurement Tasks, 285 for instance in terms of its Information Model and Protocols. 287 For Measurement Results to be truly comparable, as might be required 288 by a regulator, not only do the same Measurement Methods need to be 289 used to assess Metrics, but also the set of Measurement Tasks should 290 follow a similar Measurement Schedule and be of similar number. The 291 details of such a characterisation plan are beyond the scope of work 292 in IETF although certainly facilitated by IETF's work. 294 Messages are transferred over a secure Channel. A Control Channel is 295 between the Controller and a MA; the Control Protocol delivers 296 Instruction Messages to the MA and Capabilities, Failure and Logging 297 Information in the reverse direction. A Report Channel is between a 298 MA and Collector, and the Report Protocol delivers Reports to the 299 Collector. 301 Finally we introduce several components that are outside the scope of 302 initial LMAP work and will be provided through existing protocols or 303 applications. They affect how the measurement system uses the 304 Measurement Results and how it decides what set of Measurement Tasks 305 to perform. 307 The MA needs to be bootstrapped with initial details about its 308 Controller, including authentication credentials. The LMAP work 309 considers the bootstrap process, since it affects the Information 310 Model. However, LMAP does not define a bootstrap protocol, since it 311 is likely to be technology specific and could be defined by the 312 Broadband Forum, CableLabs or IEEE depending on the device. Possible 313 protocols are SNMP, NETCONF or (for Home Gateways) CPE WAN Management 314 Protocol (CWMP) from the Auto Configuration Server (ACS) (as 315 specified in TR-069 [TR-069]). 317 A Subscriber parameter database contains information about the line, 318 such as the customer's broadband contract (perhaps 2, 40 or 80Mb/s), 319 the line technology (DSL or fibre), the time zone where the MA is 320 located, and the type of home gateway and MA. These parameters are 321 already gathered and stored by existing operations systems. They may 322 affect the choice of what Measurement Tasks to run and how to 323 interpret the Measurement Results. For example, a download test 324 suitable for a line with an 80Mb/s contract may overwhelm a 2Mb/s 325 line. 327 A results repository records all Measurement Results in an equivalent 328 form, for example an SQL database, so that they can easily be 329 accessed by the data analysis tools. 331 The data analysis tools receive the results from the Collector or via 332 the Results repository. They might visualise the data or identify 333 which component or link is likely to be the cause of a fault or 334 degradation. This information could help the Controller decide what 335 follow-up Measurement Task to perform in order to diagnose a fault. 336 The data analysis tools also need to understand the Subscriber's 337 service information, for example the broadband contract. 339 ^ 340 | 341 +-------------+ IPPM 342 +---------------+ Measurement | Measurement | Scope 343 | Measurement |<------------>| Peer | | 344 | Agent | Traffic +-------------+ v 345 +------->| | ^ 346 | +---------------+ | 347 | ^ | | 348 | Instruction | | Report | 349 | | +-----------------+ | 350 | | | | 351 | | v LMAP 352 | +------------+ +------------+ Scope 353 | | Controller | | Collector | | 354 | +------------+ +------------+ v 355 | ^ ^ | ^ 356 | | | | | 357 | | +----------+ | | 358 | | | v | 359 +------------+ +----------+ +--------+ +----------+ | 360 |Bootstrapper| |Subscriber|--->| data |<---|repository| Out 361 +------------+ |parameter | |analysis| +----------+ of 362 |database | | tools | Scope 363 +----------+ +--------+ | 364 | 365 v 367 Figure 1: Schematic of main elements of an LMAP-based 368 measurement system 369 (showing the elements in and out of the scope of initial LMAP work) 371 3. Terminology 373 This section defines terminology for LMAP. Please note that defined 374 terms are capitalized. 376 Bootstrap: A process that integrates a Measurement Agent into a 377 measurement system. 379 Capabilities: Information about the performance measurement 380 capabilities of the MA, in particular the Measurement Method roles 381 and measurement protocol roles that it can perform, and the device 382 hosting the MA, for example its interface type and speed, but not 383 dynamic information. 385 Channel: A bi-directional logical connection that is defined by a 386 specific Controller and MA, or Collector and MA, plus associated 387 security. 389 Collector: A function that receives a Report from a Measurement 390 Agent. 392 Controller: A function that provides a Measurement Agent with its 393 Instruction. 395 Control Channel: a Channel between a Controller and a MA over which 396 Instruction Messages and Capabilities, Failure and Logging 397 Information are sent. 399 Control Protocol: The protocol delivering Instruction(s) from a 400 Controller to a Measurement Agent. It also delivers Capabilities, 401 Failure and Logging Information from the Measurement Agent to the 402 Controller. It can also be used to update the MA's configuration. 404 Cycle-ID: A tag that is sent by the Controller in an Instruction and 405 echoed by the MA in its Report. The same Cycle-ID is used by several 406 MAs that use the same Measurement Method for a Metric with the same 407 Input Parameters. Hence the Cycle-ID allows the Collector to easily 408 identify Measurement Results that should be comparable. 410 Data Model: The implementation of an Information Model in a 411 particular data modelling language [RFC3444]. 413 Environmental Constraint: A parameter that is measured as part of the 414 Measurement Task, its value determining whether the rest of the 415 Measurement Task proceeds. 417 Failure Information: Information about the MA's failure to action or 418 execute an Instruction, whether concerning Measurement Tasks or 419 Reporting. 421 Group-ID: An identifier of a group of MAs. 423 Information Model: The protocol-neutral definition of the semantics 424 of the Instructions, the Report, the status of the different elements 425 of the measurement system as well of the events in the system 426 [RFC3444]. 428 Input Parameter: A parameter whose value is left open by the Metric 429 and its Measurement Method and is set to a specific value in a 430 Measurement Task. Altering the value of an Input Parameter does not 431 change the fundamental nature of the Measurement Task. 433 Instruction: The description of Measurement Tasks for a MA to perform 434 and the details of the Report for it to send. It is the collective 435 description of the Measurement Task configurations, the configuration 436 of the Measurement Schedules, the configuration of the Report 437 Channel(s), the configuration of Report Schedule(s), and the details 438 of any suppression. 440 Instruction Message: The message that carries an Instruction from a 441 Controller to a Measurement Agent. 443 Logging Information: Information about the operation of the 444 Measurement Agent and which may be useful for debugging. 446 Measurement Agent (MA): The function that receives Instruction 447 Messages from a Controller and operates the Instruction by executing 448 Measurement Tasks (using protocols outside the initial LMAP work 449 scope and perhaps in concert with one or more other Measurement 450 Agents or Measurement Peers) and (if part of the Instruction) by 451 reporting Measurement Results to a Collector or Collectors. 453 Measurement Agent Identifier (MA-ID): a UUID [RFC4122] that 454 identifies a particular MA and is configured as part of the 455 Bootstrapping process. 457 Measurement Method: The process for assessing the value of a Metric; 458 the process of measuring some performance or reliability parameter 459 associated with the transfer of traffic; where this process involves 460 multiple MAs or MPs, each may perform different roles. 462 Measurement Peer (MP): The function that assists a Measurement Agent 463 with Measurement Tasks and does not have an interface to the 464 Controller or Collector. 466 Measurement Result: The output of a single Measurement Task (the 467 value obtained for the parameter of interest or Metric). 469 Measurement Schedule: The schedule for performing Measurement Tasks. 471 Measurement Task: The action performed by a particular Measurement 472 Agent that consists of the single assessment of a Metric through 473 operation of a Measurement Method role at a particular time, with all 474 of the role's Input Parameters set to specific values. 476 Measurement Traffic: the packet(s) generated by some types of 477 Measurement Method that involve measuring some parameter associated 478 with the transfer of the packet(s). 480 Metric: The quantity related to the performance and reliability of 481 the network that we'd like to know the value of, and that is 482 carefully specified. 484 Report: The set of Measurement Results and other associated 485 information (as defined by the Instruction). The Report is sent by a 486 Measurement Agent to a Collector. 488 Report Channel: a communications channel between a MA and a 489 Collector, which is defined by a specific MA, Collector, Report 490 Schedule and associated security, and over which Reports are sent. 492 Report Protocol: The protocol delivering Report(s) from a Measurement 493 Agent to a Collector. 495 Report Schedule: the schedule for sending Reports to a Collector. 497 Subscriber: An entity (associated with one or more users) that is 498 engaged in a subscription with a service provider. 500 Suppression: the temporary cessation of Measurement Tasks. 502 4. Constraints 504 The LMAP framework makes some important assumptions, which constrain 505 the scope of the initial LMAP work. 507 4.1. Measurement system is under the direction of a single organisation 509 In the LMAP framework, the measurement system is under the direction 510 of a single organisation that is responsible for any impact that its 511 measurements have on a user's quality of experience and privacy. 512 Clear responsibility is critical given that a misbehaving large-scale 513 measurement system could potentially harm user experience, user 514 privacy and network security. 516 However, the components of an LMAP measurement system can be deployed 517 in administrative domains that are not owned by the measuring 518 organisation. Thus, the system of functions deployed by a single 519 organisation constitutes a single LMAP domain which may span 520 ownership or other administrative boundaries. 522 4.2. Each MA may only have a single Controller at any point in time 524 A MA is instructed by one Controller and is in one measurement 525 system. The constraint avoids different Controllers giving a MA 526 conflicting instructions and so means that the MA does not have to 527 manage contention between multiple Measurement (or Report) Schedules. 528 This simplifies the design of MAs (critical for a large-scale 529 infrastructure) and allows a Measurement Schedule to be tested on 530 specific types of MA before deployment to ensure that the end user 531 experience is not impacted (due to CPU, memory or broadband-product 532 constraints). 534 An operator may have several Controllers, perhaps with a Controller 535 for different types of MA (home gateways, tablets) or location 536 (Ipswich, Edinburgh). 538 5. LMAP Protocol Model 540 A protocol model [RFC4101] presents an architectural model for how 541 the protocol operates and needs to answer three basic questions: 543 1. What problem is the protocol trying to achieve? 545 2. What messages are being transmitted and what do they mean? 547 3. What are the important, but unobvious, features of the protocol? 549 An LMAP system goes through the following phases: 551 o a bootstrapping process before the MA can take part in the other 552 three phases 554 o a Control Protocol, which delivers Instruction Messages from a 555 Controller to a MA, detailing what Measurement Tasks the MA should 556 perform and when, and how it should report the Measurement 557 Results. It also delivers Capabilities, Failure and logging 558 Information from a MA to its Controller. Finally, it allows the 559 Controller to update the MA's configuration. 561 o the actual Measurement Tasks, which measure some performance or 562 reliability parameter(s) associated with the transfer of packets. 563 The LMAP work does not define Metrics and Measurement Methods, 564 these are define elsewhere (e.g. IPPM). 566 o a Report Protocol, which delivers Reports from a MA to a 567 Collector. The Report contains the Measurement Results. 569 The diagrams show the various LMAP messages and uses the following 570 convention: 572 o (optional): indicated by round brackets 574 o [potentially repeated]: indicated by square brackets 576 The protocol model is closely related to the Information Model 577 [I-D.ietf-lmap-information-model], which is the abstract definition 578 of the information carried by the protocol model. The purpose of 579 both is to provide a protocol and device independent view, which can 580 be implemented via specific protocols. LMAP defines a specific 581 Control Protocol and Report Protocol, but others could be defined by 582 other standards bodies or be proprietary. However it is important 583 that they all implement the same Information Model and protocol 584 model, in order to ease the definition, operation and 585 interoperability of large-scale measurement systems. 587 5.1. Bootstrapping process 589 The primary purpose of bootstrapping is to enable a MA to be 590 integrated into a measurement system. The MA retrieves information 591 about itself (like its identity in the measurement system) and about 592 the Controller, the Controller learns information about the MA, and 593 they learn about security information to communicate (such as 594 certificates and credentials). 596 Whilst this memo considers the bootstrapping process, it is beyond 597 the scope of initial LMAP work to define a bootstrap mechanism, as it 598 depends on the type of device and access. 600 As a result of the bootstrapping process the MA learns information 601 with the following aims ([I-D.ietf-lmap-information-model] defines 602 the consequent list of information elements): 604 o its identifier, either its MA-ID or a device identifier such as 605 its MAC or both. 607 o (optionally) a Group-ID. A Group-ID would be shared by several 608 MAs and could be useful for privacy reasons. For instance, 609 reporting the Group-ID and not the MA-ID could hinder tracking of 610 a mobile device 612 o the Control Channel, which is defined by: 614 * the address which identifies the Control Channel, such as the 615 Controller's FQDN (Fully Qualified Domain Name) [RFC1035]) 617 * security information (for example to enable the MA to decrypt 618 the Instruction Message and encrypt messages sent to the 619 Controller) 621 The details of the bootstrapping process are device /access specific. 622 For example, the information could be in the firmware, manually 623 configured or transferred via a protocol like TR-069 [TR-069]. There 624 may be a multi-stage process where the MA contacts the device at a 625 'hard-coded' address, which replies with the bootstrapping 626 information. 628 The MA must learn its MA-ID before getting an Instruction, either 629 during Bootstrapping or via configuration (Section 5.2.1). 631 5.2. Control Protocol 633 The primary purpose of the Control Protocol is to allow the 634 Controller to configure a Measurement Agent with an Instruction about 635 what Measurement Tasks to do, when to do them, and how to report the 636 Measurement Results (Section 5.2.2). The Measurement Agent then acts 637 on the Instruction autonomously. The Control Protocol also enables 638 the MA to inform the Controller about its Capabilities and any 639 Failure and logging Information (Section 5.2.2). Finally, the 640 Control Protocol allows the Controller to update the MA's 641 configuration. 643 5.2.1. Configuration 645 Configuration allows the Controller to update the MA about some or 646 all of the information that it obtained during the bootstrapping 647 process: the MA-ID, the (optional) Group-ID and the Control Channel. 648 The measurement system might use Configuration for several reasons. 649 For example, the bootstrapping process could 'hard code' the MA with 650 details of an initial Controller, and then the initial Controller 651 could configure the MA with details about the Controller that sends 652 Instruction Messages. (Note that a MA only has one Control Channel, 653 and so is associated with only one Controller, at any moment.) 655 Note that an implementation may choose to combine Configuration 656 information and an Instruction Message into a single message. 658 +-----------------+ +-------------+ 659 | | | Measurement | 660 | Controller |======================================| Agent | 661 +-----------------+ +-------------+ 663 Configuration information: -> 664 (MA-ID), 665 (Group-ID), 666 (Control Channel) 667 <- Response(details) 669 5.2.2. Instruction 671 The Instruction is the description of the Measurement Tasks for a 672 Measurement Agent to do and the details of the Measurement Reports 673 for it to send. In order to update the Instruction the Controller 674 uses the Control Protocol to send an Instruction Message over the 675 Control Channel. 677 +-----------------+ +-------------+ 678 | | | Measurement | 679 | Controller |======================================| Agent | 680 +-----------------+ +-------------+ 682 Instruction: -> 683 [(Measurement Task configuration( 684 [Input Parameter], 685 (interface), 686 (Cycle-ID))), 687 (Report Channel), 688 (Measurement Schedule), 689 (Report Schedule), 690 (Suppression information)] 691 <- Response(details) 693 The Instruction defines information with the following aims 694 ([I-D.ietf-lmap-information-model] defines the consequent list of 695 information elements): 697 o the Measurement Task configurations, each of which needs: 699 * the Metric, specified as a URI to a registry entry; it includes 700 the specification of a Measurement Method. The registry could 701 be defined by the IETF [I-D.manyfolks-ippm-metric-registry], 702 locally by the operator of the measurement system or perhaps by 703 another standards organisation. 705 * the Measurement Method role. For some Measurement Methods, 706 different parties play different roles; for example (figure A3 707 in the Appendix) an iperf sender and receiver. Each Metric and 708 its associated Measurement Method will describe all measurement 709 roles involved in the process. Thus, the Measurement Method 710 role is an Input Parameter. 712 * a boolean flag (suppress or do-not-suppress) indicating how 713 such a Measurement Task is impacted by a Suppression message 714 (see Section 5.2.2.1). Thus, the flag is an Input Parameter. 716 * any Input Parameters that need to be set for the Metric and the 717 Measurement Method, such as the address of a Measurement Peer 718 (or other Measurement Agent) that may be involved in a 719 Measurement Task, and for the measurement protocol used, such 720 as protocol role(s). 722 * if the device with the MA has multiple interfaces, then the 723 interface to use (if not defined, then the default interface is 724 used) 726 o configuration of the Measurement Schedules, each of which needs: 728 * the timing of when the Measurement Tasks are to be performed. 729 Possible types of timing are periodic, calendar-based periodic, 730 one-off immediate and one-off at a future time 732 o configuration of the Report Channels, each of which needs: 734 * the address of the Collector, for instance its URL 736 * security for this Report Channel, for example the X.509 737 certificate 739 o configuration of the Report Schedules, each of which needs: 741 * the timing of when reporting is to be performed. For instance, 742 every hour or immediately. 744 o Suppression information, if any (see Section 5.2.1.1) 746 A single Instruction Message may contain some or all of the above 747 parts. The finest level of granularity possible in an Instruction 748 Message is determined by the implementation and operation of the 749 Control Protocol. For example, a single Instruction Message may add 750 or update an individual Measurement Schedule - or it may only update 751 the complete set of Measurement Schedules; a single Instruction 752 Message may update both Measurement Schedules and Measurement Task 753 configurations - or only one at a time; and so on. 755 The MA informs the Controller that it has successfully understood the 756 Instruction Message, or that it cannot action the Instruction - for 757 example, if it doesn't include a parameter that is mandatory for the 758 requested Metric and Measurement Method, or it is missing details of 759 the target Collector. 761 The Instruction Message instructs the MA; the Control Protocol does 762 not allow the MA to negotiate, as this would add complexity to the 763 MA, Controller and Control Protocol for little benefit. 765 5.2.2.1. Suppression 767 The Instruction may include Suppression information. The purpose of 768 Suppression is to enable the Controller to instruct the MA not to 769 perform Measurement Tasks. It is used if the measurement system 770 wants to eliminate inessential traffic, because there is some 771 unexpected network issue for example. 773 The Suppression information may include any of the following optional 774 fields: 776 o a set of Measurement Tasks to suppress; the others are not 777 suppressed. For example, this could be useful if a particular 778 Measurement Task is overloading a Measurement Peer. 780 o a set of Measurement Schedules to suppress; the others are not 781 suppressed. For example, suppose the measurement system has 782 defined two Schedules, one with the most critical Measurement 783 Tasks and the other with less critical ones that create a lot of 784 Measurement Traffic, then it may only want to suppress the second. 786 o if the Suppression information includes neither a set of 787 Measurement Tasks nor a set of Measurement Schedules, then the MA 788 does not begin new Measurement Tasks that have the boolean flag 789 set to "suppress"; however, the MA does begin new Measurement 790 Tasks that have the flag set to "do-not-suppress". 792 o a start time, at which suppression begins. If absent, then 793 Suppression begins immediately. 795 o an end time, at which suppression ends. If absent, then 796 Suppression continues until the MA receives an un-Suppress 797 message. 799 o a demand that the MA immediately ends on-going Measurement Task(s) 800 that are tagged for suppression (and deletes the associated 801 partial Measurement Result(s)). This could be useful in the case 802 of a network emergency so that the operator can eliminate all 803 inessential traffic as rapidly as possible. If absent, the MA 804 completes on-going Measurement Tasks. 806 So the default action (if none of the optional fields is set) is that 807 the MA does not begin any new Measurement Task with the "suppress" 808 flag. 810 An un-Suppress message instructs the MA no longer to suppress, 811 meaning that the MA once again begins new Measurement Tasks, 812 according to its Measurement Schedule. 814 Note that Suppression is not intended to permanently stop a 815 Measurement Task (instead, the Controller should send a new 816 Measurement Schedule), nor to permanently disable a MA (instead, some 817 kind of management action is suggested). 819 +-----------------+ +-------------+ 820 | | | Measurement | 821 | Controller |===================================| Agent | 822 +-----------------+ +-------------+ 824 Suppress: 825 [(Measurement Task), -> 826 (Measurement Schedule), 827 [start time], 828 [end time], 829 [on-going suppressed?]] 831 Un-suppress -> 833 5.2.3. Capabilities and Failure information 835 The Control Protocol also enables the MA to inform the Controller 836 about various information, such as its Capabilities and any Failures. 837 It is also possible to use a device-specific mechanism which is 838 beyond the scope of the initial LMAP work. 840 Capabilities are information about the MA that the Controller needs 841 to know in order to correctly instruct the MA, such as: 843 o the Measurement Method (roles) that the MA supports 845 o the measurement protocol types and roles that the MA supports 846 o the interfaces that the MA has 848 o the version of the MA 850 o the version of the hardware, firmware or software of the device 851 with the MA 853 o but not dynamic information like the currently unused CPU, memory 854 or battery life of the device with the MA. 856 Failure information concerns why the MA has been unable to execute a 857 Measurement Task or deliver a Report, for example: 859 o the Measurement Task failed to run properly because the MA 860 (unexpectedly) has no spare CPU cycles 862 o the MA failed record the Measurement Results because it 863 (unexpectedly) is out of spare memory 865 o a Report failed to deliver Measurement Results because the 866 Collector (unexpectedly) is not responding 868 o but not if a Measurement Task correctly doesn't start. For 869 example, the first step of some Measurement Methods is for the MA 870 to check there is no cross-traffic. 872 Logging information concerns how the MA is operating and may help 873 debugging, for example: 875 o the last time the MA ran a Measurement Task 877 o the last time the MA sent a Measurement Report 879 o the last time the MA received an Instruction Message 881 o whether the MA is currently Suppressing Measurement Tasks 883 Capabilities, failure and logging information are sent by the MA, 884 either in response to a request from the Controller (for example, if 885 the Controller forgets what the MA can do or otherwise wants to 886 resynchronize what it knows about the MA), or on its own initiative 887 (for example when the MA first communicates with a Controller or if 888 it becomes capable of a new Measurement Method). Another example of 889 the latter case is if the device with the MA re-boots, then the MA 890 should notify its Controller in case its Instruction needs to be 891 updated; to avoid a "mass calling event" after a widespread power 892 restoration affecting many MAs, it is sensible for an MA to pause for 893 a random delay, perhaps in the range of one minute or so. 895 +-----------------+ +-------------+ 896 | | | Measurement | 897 | Controller |===================================| Agent | 898 +-----------------+ +-------------+ 900 (Instruction: 901 [(Request Capabilities), 902 (Request Failure Information), 903 (Request Logging Information)]) -> 904 <- (Capabilities), 905 (Failure Information), 906 (Logging Information) 908 5.3. Operation of Measurement Tasks 910 This LMAP framework is neutral to what the actual Measurement Task 911 is. It does not define Metrics and Measurement Methods, these are 912 defined elsewhere (e.g. IPPM). 914 The MA carries out the Measurement Tasks as instructed, unless it 915 gets an updated Instruction. The MA acts autonomously, in terms of 916 operation of the Measurement Tasks and reporting of the Results; it 917 doesn't do a 'safety check' with the Controller to ask whether it 918 should still continue with the requested Measurement Tasks. 920 5.3.1. Starting and Stopping Measurement Tasks 922 This LMAP framework does not define a generic start and stop process, 923 since the correct approach depends on the particular Measurement 924 Task; the details are defined as part of each Measurement Method. 925 This section provides some general hints. The MA does not inform the 926 Controller about Measurement Tasks starting and stopping. 928 Before sending Measurement Traffic the MA may run a pre-check. (The 929 pre-check could be defined as a separate, preceding Task or as the 930 first part of a larger Task.) Action could include: 932 o the MA checking that there is no cross-traffic. In other words, a 933 check that the end-user isn't already sending traffic; 935 o the MA checking with the Measurement Peer (or other Measurement 936 Agent involved in the Measurement Task) that it can handle a new 937 Measurement Task (in case, for example, the Measurement Peer is 938 already handling many Measurement Tasks with other MAs); 940 o sending traffic that probes the path to check it isn't overloaded; 941 o checking that the device with the MA has enough resources to 942 execute the Measurement Task reliably. Note that the designer of 943 the measurement system should ensure that the device's 944 capabilities are normally sufficient to comfortably operate the 945 Measurement Tasks. 947 It is possible that similar checks continue during the Measurement 948 Task, especially one that is long-running and/or creates a lot of 949 Measurement Traffic, and might lead to it being abandoned whilst in- 950 progress. A Measurement Task could also be abandoned in response to 951 a "suppress" message (see Section 5.2.1). Action could include: 953 o For 'upload' tests, the MA not sending traffic 955 o For 'download' tests, the MA closing the TCP connection or sending 956 a TWAMP Stop control message [RFC5357]. 958 The Controller may want a MA to run the same Measurement Task 959 indefinitely (for example, "run the 'upload speed' Measurement Task 960 once an hour until further notice"). To avoid the MA generating 961 traffic forever after a Controller has permanently failed (or 962 communications with the Controller have failed), the MA can be 963 configured with a time limit; if the MA doesn't hear from the 964 Controller for this length of time, then it stops operating 965 Measurement Tasks. 967 5.3.2. Overlapping Measurement Tasks 969 It is possible that a MA starts a new Measurement Task before another 970 Measurement Task has completed. This may be intentional (the way 971 that the measurement system has designed the Measurement Schedules), 972 but it could also be unintentional - for instance, if a Measurement 973 Task has a 'wait for X' step which pauses for an unexpectedly long 974 time. The operator of the measurement system can handle (or not) 975 overlapping Measurement Tasks in any way they choose - it is a policy 976 or implementation issue and not the concern of LMAP. Some possible 977 approaches are: to configure the MA not to begin the second 978 Measurement Task; to start the second Measurement Task as usual; for 979 the action to be an Input Parameter of the Measurement Task; and so 980 on. 982 It may be important to include in the Measurement Report the fact 983 that the Measurement Task overlapped with another. 985 5.4. Report Protocol 987 The primary purpose of the Report Protocol is to allow a Measurement 988 Agent to report its Measurement Results to a Collector, along with 989 the context in which they were obtained. 991 +-----------------+ +-------------+ 992 | | | Measurement | 993 | Collector |===================================| Agent | 994 +-----------------+ +-------------+ 996 <- Report: 997 [MA-ID &/or Group-ID], 998 [Measurement Result], 999 [details of Measurement Task] 1000 ACK -> 1002 The Report contains: 1004 o the MA-ID or a Group-ID (to anonymise results) 1006 o the actual Measurement Results, including the time they were 1007 measured 1009 o the details of the Measurement Task (to avoid the Collector having 1010 to ask the Controller for this information later) 1012 o perhaps the Subscriber's service parameters (see Section 5.4.1). 1014 The MA sends Reports as defined by the Instruction. It is possible 1015 that the Instruction tells the MA to report the same Results to more 1016 than one Collector, or to report a different subset of Results to 1017 different Collectors. It is also possible that a Measurement Task 1018 may create two (or more) Measurement Results, which could be reported 1019 differently (for example, one Result could be reported periodically, 1020 whilst the second Result could be an alarm that is created as soon as 1021 the measured value of the Metric crosses a threshold and that is 1022 reported immediately). 1024 Optionally, a Report is not sent when there are no Measurement 1025 Results. 1027 In the initial LMAP Information Model and Report Protocol, for 1028 simplicity we assume that all Measurement Results are reported as-is, 1029 but allow extensibility so that a measurement system (or perhaps a 1030 second phase of LMAP) could allow a MA to: 1032 o label, or perhaps not include, Measurement Results impacted by, 1033 for instance, cross-traffic or the Measurement Peer (or other 1034 Measurement Agent) being busy 1036 o label Measurement Results obtained by a Measurement Task that 1037 overlapped with another 1039 o not report the Measurement Results if the MA believes that they 1040 are invalid 1042 o detail when Suppression started and ended 1044 5.4.1. Reporting of Subscriber's service parameters 1046 The Subscriber's service parameters are information about his/her 1047 broadband contract, line rate and so on. Such information is likely 1048 to be needed to help analyse the Measurement Results, for example to 1049 help decide whether the measured download speed is reasonable. 1051 The information could be transferred directly from the Subscriber 1052 parameter database to the data analysis tools. It may also be 1053 possible to transfer the information via the MA. How (and if) the MA 1054 knows such information is likely to depend on the device type. The 1055 MA could either include the information in a Measurement Report or 1056 separately. 1058 5.5. Operation of LMAP over the underlying packet transfer mechanism 1060 The above sections have described LMAP's protocol model. Other 1061 specifications will define the actual Control and Report Protocols, 1062 possibly operating over an existing protocol, such as REST-style 1063 HTTP(S). It is also possible that a different choice is made for the 1064 Control and Report Protocols, for example NETCONF-YANG and IPFIX 1065 respectively. 1067 From an LMAP perspective, the Controller needs to know that the MA 1068 has received the Instruction Message, or at least that it needs to be 1069 re-sent as it may have failed to be delivered. Similarly the MA 1070 needs to know about the delivery of Capabilities and Failure 1071 information to the Controller and Reports to the Collector. How this 1072 is done depends on the design of the Control and Report Protocols and 1073 the underlying packet transfer mechanism. 1075 For the Control Protocol, the underlying packet transfer mechanism 1076 could be: 1078 o a 'push' protocol (that is, from the Controller to the MA) 1079 o a multicast protocol (from the Controller to a group of MAs) 1081 o a 'pull' protocol. The MA periodically checks with Controller if 1082 the Instruction has changed and pulls a new Instruction if 1083 necessary. A pull protocol seems attractive for a MA behind a NAT 1084 (as is typical for a MA on an end-user's device), so that it can 1085 initiate the communications. A pull mechanism is likely to 1086 require the MA to be configured with how frequently it should 1087 check in with the Controller, and perhaps what it should do if the 1088 Controller is unreachable after a certain number of attempts. 1090 o a hybrid protocol. In addition to a pull protocol, the Controller 1091 can also push an alert to the MA that it should immediately pull a 1092 new Instruction. 1094 For the Report Protocol, the underlying packet transfer mechanism 1095 could be: 1097 o a 'push' protocol (that is, from the MA to the Collector) 1099 o perhaps supplemented by the ability for the Collector to 'pull' 1100 Measurement Results from a MA. 1102 5.6. Items beyond the scope of the initial LMAP work 1104 There are several potential interactions between LMAP elements that 1105 are beyond the scope of the initial LMAP work: 1107 1. It does not define a coordination process between MAs. Whilst a 1108 measurement system may define coordinated Measurement Schedules 1109 across its various MAs, there is no direct coordination between 1110 MAs. 1112 2. It does not define interactions between the Collector and 1113 Controller. It is quite likely that there will be such 1114 interactions, optionally intermediated by the data analysis 1115 tools. For example, if there is an "interesting" Measurement 1116 Result then the measurement system may want to trigger extra 1117 Measurement Tasks that explore the potential cause in more 1118 detail; or if the Collector unexpectedly does not hear from a MA, 1119 then the measurement system may want to trigger the Controller to 1120 send a fresh Instruction Message to the MA. 1122 3. It does not define coordination between different measurement 1123 systems. For example, it does not define the interaction of a MA 1124 in one measurement system with a Controller or Collector in a 1125 different measurement system. Whilst it is likely that the 1126 Control and Report Protocols could be re-used or adapted for this 1127 scenario, any form of coordination between different 1128 organisations involves difficult commercial and technical issues 1129 and so, given the novelty of large-scale measurement efforts, any 1130 form of inter-organisation coordination is outside the scope of 1131 the initial LMAP work. Note that a single MA is instructed by a 1132 single Controller and is only in one measurement system. 1134 * An interesting scenario is where a home contains two 1135 independent MAs, for example one controlled by a regulator and 1136 one controlled by an ISP. Then the Measurement Traffic of one 1137 MA is treated by the other MA just like any other end-user 1138 traffic. 1140 4. It does not consider how to prevent a malicious party "gaming the 1141 system". For example, where a regulator is running a measurement 1142 system in order to benchmark operators, a malicious operator 1143 could try to identify the broadband lines that the regulator was 1144 measuring and prioritise that traffic. It is assumed this is a 1145 policy issue and would be dealt with through a code of conduct 1146 for instance. 1148 5. It does not define how to analyse Measurement Results, including 1149 how to interpret missing Results. 1151 6. It does not specifically define a end-user-controlled measurement 1152 system, see sub-section 5.6.1. 1154 5.6.1. End-user-controlled measurement system 1156 This framework concentrates on the cases where an ISP or a regulator 1157 runs the measurement system. However, we expect that LMAP 1158 functionality will also be used in the context of an end-user- 1159 controlled measurement system. There are at least two ways this 1160 could happen (they have various pros and cons): 1162 1. an end-user could somehow request the ISP- (or regulator-) run 1163 measurement system to test his/her line. The ISP (or regulator) 1164 Controller would then send an Instruction to the MA in the usual 1165 LMAP way. 1167 2. an end-user could deploy their own measurement system, with their 1168 own MA, Controller and Collector. For example, the user could 1169 implement all three functions onto the same end-user-owned end 1170 device, perhaps by downloading the functions from the ISP or 1171 regulator. Then the LMAP Control and Report Protocols do not 1172 need to be used, but using LMAP's Information Model would still 1173 be beneficial. The Measurement Peer (or other MA involved in the 1174 Measurement Task) could be in the home gateway or outside the 1175 home network; in the latter case the Measurement Peer is highly 1176 likely to be run by a different organisation, which raises extra 1177 privacy considerations. 1179 In both cases there will be some way for the end-user to initiate the 1180 Measurement Task(s). The mechanism is outside the scope of the 1181 initial LMAP work, but could include the user clicking a button on a 1182 GUI or sending a text message. Presumably the user will also be able 1183 to see the Measurement Results, perhaps summarised on a webpage. It 1184 is suggested that these interfaces conform to the LMAP guidance on 1185 privacy in Section 8. 1187 6. Deployment considerations 1189 The Appendix has some examples of possible deployment arrangements of 1190 Measurement Agents and Peers. 1192 6.1. Controller and the measurement system 1194 The Controller should understand both the MA's LMAP Capabilities (for 1195 instance what Metrics and Measurement Methods it can perform) and 1196 about the MA's other capabilities like processing power and memory. 1197 This allows the Controller to make sure that the Measurement Schedule 1198 of Measurement Tasks and the Reporting Schedule are sensible for each 1199 MA that it instructs. 1201 An Instruction is likely to include several Measurement Tasks. 1202 Typically these run at different times, but it is also possible for 1203 them to run at the same time. Some Tasks may be compatible, in that 1204 they do not affect each other's Results, whilst with others great 1205 care would need to be taken. 1207 The Controller should ensure that the Measurement Tasks do not have 1208 an adverse effect on the end user. Tasks, especially those that 1209 generate a substantial amount of traffic, will often include a pre- 1210 check that the user isn't already sending traffic (Section 5.3). 1211 Another consideration is whether Measurement Traffic will impact a 1212 Subscriber's bill or traffic cap. 1214 The different elements of the Instruction can be updated 1215 independently. For example, the Measurement Tasks could be 1216 configured with different Input Parameters whilst keeping the same 1217 Measurement Schedule. In general this should not create any issues, 1218 since Metrics and their associated Measurement Methods should be 1219 defined so their fundamental nature does not change for a new value 1220 of Input Parameter. There could be a problem if, for example, a 1221 Measurement Task involving a 1kB file upload could be changed into a 1222 1GB file upload. 1224 A measurement system may have multiple Controllers (but note the 1225 overriding principle that a single MA is instructed by a single 1226 Controller at any point in time (Section 4.2)). For example, there 1227 could be different Controllers for different types of MA (home 1228 gateways, tablets) or locations (Ipswich, Edinburgh), for load 1229 balancing or to cope with failure of one Controller. 1231 The measurement system also needs to consider carefully how to 1232 interpret missing Results; for example, if the missing Results are 1233 ignored and the lack of a Report is caused by its broadband being 1234 broken, then the estimate of overall performance, averaged across all 1235 MAs, would be too optimistic. 1237 6.2. Measurement Agent 1239 The Measurement Agent could take a number of forms: a dedicated 1240 probe, software on a PC, embedded into an appliance, or even embedded 1241 into a gateway. A single site (home, branch office etc.) that is 1242 participating in a measurement could make use of one or multiple 1243 Measurement Agents or Measurement Peers in a single measurement. 1245 The Measurement Agent could be deployed in a variety of locations. 1246 Not all deployment locations are available to every kind of 1247 Measurement Agent. There are also a variety of limitations and 1248 trade-offs depending on the final placement. The next sections 1249 outline some of the locations a Measurement Agent may be deployed. 1250 This is not an exhaustive list and combinations may also apply. 1252 6.2.1. Measurement Agent on a networked device 1254 A MA may be embedded on a device that is directly connected to the 1255 network, such as a MA on a smartphone. Other examples include a MA 1256 downloaded and installed on a subscriber's laptop computer or tablet 1257 when the network service is provided on wired or other wireless radio 1258 technologies, such as Wi-Fi. 1260 6.2.2. Measurement Agent embedded in site gateway 1262 A Measurement Agent embedded with the site gateway, for example a 1263 home router or the edge router of a branch office in a managed 1264 service environment, is one of better places the Measurement Agent 1265 could be deployed. All site-to-ISP traffic would traverse through 1266 the gateway. So, Measurement Methods that measure user traffic could 1267 easily be performed. Similarly, due to this user traffic visibility, 1268 a Measurement Method that generates Measurement Traffic could ensure 1269 it does not compete with user traffic. Generally NAT and firewall 1270 services are built into the gateway, allowing the Measurement Agent 1271 the option to offer its Controller-facing management interface 1272 outside of the NAT/firewall. This placement of the management 1273 interface allows the Controller to unilaterally contact the 1274 Measurement Agent for instructions. However, a Measurement Agent on 1275 a site gateway (whether end-user service-provider owned) will 1276 generally not be directly available for over the top providers, the 1277 regulator, end users or enterprises. 1279 6.2.3. Measurement Agent embedded behind site NAT /Firewall 1281 The Measurement Agent could also be embedded behind a NAT, a 1282 firewall, or both. In this case the Controller may not be able to 1283 unilaterally contact the Measurement Agent unless either static port 1284 forwarding or firewall pin holing is configured. Configuring port 1285 forwarding could use protocols such as PCP [RFC6887], TR-069 [TR-069] 1286 or UPnP [UPnP]. To prop open the firewall, the Measurement Agent 1287 could send keepalives towards the Controller (and perhaps use these 1288 also as a network reachability test). 1290 6.2.4. Multi-homed Measurement Agent 1292 If the device with the Measurement Agent is single homed then there 1293 is no confusion about what interface to measure. Similarly, if the 1294 MA is at the gateway and the gateway only has a single WAN-side and a 1295 single LAN-side interface, there is little confusion - for 1296 Measurement Methods that generate Measurement Traffic, the location 1297 of the other MA or Measurement Peer determines whether the WAN or LAN 1298 is measured. 1300 However, the device with the Measurement Agent may be multi-homed. 1301 For example, a home or campus may be connected to multiple broadband 1302 ISPs, such as a wired and wireless broadband provider, perhaps for 1303 redundancy or load- sharing. It may also be helpful to think of dual 1304 stack IPv4 and IPv6 broadband devices as multi-homed. More 1305 generally, Section 3.2 of [I-D.ietf-homenet-arch] describes dual- 1306 stack and multi-homing topologies that might be encountered in a home 1307 network, [RFC6419] provides the current practices of multi-interfaces 1308 hosts, and the Multiple Interfaces (mif) working group covers cases 1309 where hosts are either directly attached to multiple networks 1310 (physical or virtual) or indirectly (multiple default routers, etc.). 1311 In these cases, there needs to be clarity on which network 1312 connectivity option is being measured. 1314 One possibility is to have a Measurement Agent per interface. Then 1315 the Controller's choice of MA determines which interface is measured. 1316 However, if a MA can measure any of the interfaces, then the 1317 Controller defines in the Instruction which interface the MA should 1318 use for a Measurement Task; if the choice of interface is not defined 1319 then the MA uses the default one. Explicit definition is preferred 1320 if the measurement system wants to measure the performance of a 1321 particular network, whereas using the default is better if the 1322 measurement system wants to include the impact of the MA's interface 1323 selection algorithm. In any case, the Measurement Result should 1324 include the network that was measured. 1326 6.2.5. Measurement Agent embedded in ISP Network 1328 A MA may be embedded on a device that is part of an ISP's network, 1329 such as a router or switch. Usually the network devices with an 1330 embedded MA will be strategically located, such as a Carrier Grade 1331 NAT or ISP Gateway. [I-D.ietf-ippm-lmap-path] gives many examples 1332 where a MA might be located within a network to provide an 1333 intermediate measurement point on the end-to-end path. Other 1334 examples include a network device whose primary role is to host MA 1335 functions and the necessary measurement protocol. 1337 6.3. Measurement Peer 1339 A Measurement Peer participates in some Measurement Methods. It may 1340 have specific functionality to enable it to participate in a 1341 particular Measurement Method. On the other hand, other Measurement 1342 Methods may require no special functionality, for example if the 1343 Measurement Agent sends a ping to example.com then the server at 1344 example.com plays the role of a Measurement Peer. 1346 A device may participate in some Measurement Methods as a Measurement 1347 Agent and in others as a Measurement Peer. 1349 Measurement Schedules should account for limited resources in a 1350 Measurement Peer when instructing a MA to execute measurements with a 1351 Measurement Peer. In some measurement protocols, such as [RFC4656] 1352 and [RFC5357], the Measurement Peer can reject a measurement session 1353 or refuse a control connection prior to setting-up a measurement 1354 session and so protect itself from resource exhaustion. This is a 1355 valuable capability because the MP may be used by more than one 1356 organisation. 1358 7. Security considerations 1360 The security of the LMAP framework should protect the interests of 1361 the measurement operator(s), the network user(s) and other actors who 1362 could be impacted by a compromised measurement deployment. The 1363 measurement system must secure the various components of the system 1364 from unauthorised access or corruption. Much of the general advice 1365 contained in section 6 of [RFC4656] is applicable here. 1367 The process to upgrade the firmware in an MA is outside the scope of 1368 the initial LMAP work, similar to the protocol to bootstrap the MAs 1369 (as specified in the charter). However, systems which provide remote 1370 upgrade must secure authorised access and integrity of the process. 1372 We assume that each Measurement Agent (MA) will receive its 1373 Instructions from a single organisation, which operates the 1374 Controller. These Instructions must be authenticated (to ensure that 1375 they come from the trusted Controller), checked for integrity (to 1376 ensure no-one has tampered with them) and not vulnerable to replay 1377 attacks. If a malicious party can gain control of the MA they can 1378 use it to launch DoS attacks at targets, reduce the end user's 1379 quality of experience and corrupt the Measurement Results that are 1380 reported to the Collector. By altering the Measurement Tasks and/or 1381 the address that Results are reported to, they can also compromise 1382 the confidentiality of the network user and the MA environment (such 1383 as information about the location of devices or their traffic). The 1384 Instruction messages also need to be encrypted to maintain 1385 confidentiality, as the information might be useful to an attacker. 1387 In some circumstances (if the MA is behind a NAT for instance), the 1388 Controller cannot contact the MA directly an so the MA must contact 1389 the Controller (the "pull" model). The Controller should ensure that 1390 its resources cannot be exhausted by a malicious party pretending to 1391 be a MA. For example, the Controller could limit the rate of "pull" 1392 requests from a single MA. 1394 Reporting by the MA must be encrypted to maintain confidentiality, so 1395 that only the authorised Collector can decrypt the results, to 1396 prevent the leakage of confidential or private information. 1397 Reporting must also be authenticated (to ensure that it comes from a 1398 trusted MA) and not vulnerable to tampering (which can be ensured 1399 through integrity and replay checks). It must not be possible to 1400 fool a MA into injecting falsified data and the results must also be 1401 held and processed securely after collection and analysis. See 1402 section 8.5.2 below for additional considerations on stored data 1403 compromise, and section 8.6 on potential mitigations for compromise. 1405 Since Collectors will be contacted repeatedly by MAs using the 1406 Collection Protocol to convey their recent results, a successful 1407 attack to exhaust the communication resources would prevent a 1408 critical operation: reporting. Therefore, all LMAP Collectors should 1409 implement technical mechanisms to: 1411 o limit the number of reporting connections from a single MA 1412 (simultaneous, and connections per unit time). 1414 o limit the transmission rate from a single MA. 1416 o limit the memory/storage consumed by a single MA's reports. 1418 o efficiently reject reporting connections from unknown sources. 1420 o separate resources if multiple authentication strengths are used, 1421 where the resources should be separated according to each class of 1422 strength. 1424 The security mechanisms described above may not be strictly necessary 1425 if the network's design ensures the LMAP components and their 1426 communications are already secured, for example potentially if they 1427 are all part of an ISP's dedicated management network. 1429 Finally, there are three other issues related to security: privacy 1430 (considered in Section 8 below), availability and 'gaming the 1431 system'. While the loss of some MAs may not be considered critical, 1432 the unavailability of the Collector could mean that valuable business 1433 data or data critical to a regulatory process is lost. Similarly, 1434 the unavailability of a Controller could mean that the MAs do not 1435 operate a correct Measurement Schedule. 1437 A malicious party could "game the system". For example, where a 1438 regulator is running a measurement system in order to benchmark 1439 operators, an operator could try to identify the broadband lines that 1440 the regulator was measuring and prioritise that traffic. Normally, 1441 this potential issue is handled by a code of conduct. It is outside 1442 the scope of the initial LMAP work to consider the issue. 1444 8. Privacy Considerations for LMAP 1446 The LMAP work considers privacy as a core requirement and will ensure 1447 that by default the Control and Report Protocols operate in a 1448 privacy-sensitive manner and that privacy features are well-defined. 1450 This section provides a set of privacy considerations for LMAP. This 1451 section benefits greatly from the timely publication of [RFC6973]. 1452 Privacy and security (Section 7) are related. In some jurisdictions 1453 privacy is called data protection. 1455 We begin with a set of assumptions related to protecting the 1456 sensitive information of individuals and organisations participating 1457 in LMAP-orchestrated measurement and data collection. 1459 8.1. Categories of Entities with Information of Interest 1461 LMAP protocols need to protect the sensitive information of the 1462 following entities, including individuals and organisations who 1463 participate in measurement and collection of results. 1465 o Individual Internet users: Persons who utilise Internet access 1466 services for communications tasks, according to the terms of 1467 service of a service agreement. Such persons may be a service 1468 Subscriber, or have been given permission by the Subscriber to use 1469 the service. 1471 o Internet service providers: Organisations who offer Internet 1472 access service subscriptions, and thus have access to sensitive 1473 information of individuals who choose to use the service. These 1474 organisations desire to protect their Subscribers and their own 1475 sensitive information which may be stored in the process of 1476 performing Measurement Tasks and collecting and Results. 1478 o Regulators: Public authorities responsible for exercising 1479 supervision of the electronic communications sector, and which may 1480 have access to sensitive information of individuals who 1481 participate in a measurement campaign. Similarly, regulators 1482 desire to protect the participants and their own sensitive 1483 information. 1485 o Other LMAP system operators: Organisations who operate measurement 1486 systems or participate in measurements in some way. 1488 Although privacy is a protection extended to individuals, we include 1489 discussion of ISPs and other LMAP system operators in this section. 1490 These organisations have sensitive information involved in the LMAP 1491 system, and many of the same dangers and mitigations are applicable. 1492 Further, the ISPs store information on their Subscribers beyond that 1493 used in the LMAP system (for instance billing information), and there 1494 should be a benefit in considering all the needs and potential 1495 solutions coherently. 1497 8.2. Examples of Sensitive Information 1499 This section gives examples of sensitive information which may be 1500 measured or stored in a measurement system, and which is to be kept 1501 private by default in the LMAP core protocols. 1503 Examples of Subscriber or authorised Internet user sensitive 1504 information: 1506 o Sub-IP layer addresses and names (MAC address, base station ID, 1507 SSID) 1509 o IP address in use 1511 o Personal Identification (real name) 1512 o Location (street address, city) 1514 o Subscribed service parameters 1516 o Contents of traffic (activity, DNS queries, destinations, 1517 equipment types, account info for other services, etc.) 1519 o Status as a study volunteer and Schedule of Measurement Tasks 1521 Examples of Internet Service Provider sensitive information: 1523 o Measurement device identification (equipment ID and IP address) 1525 o Measurement Instructions (choice of measurements) 1527 o Measurement Results (some may be shared, others may be private) 1529 o Measurement Schedule (exact times) 1531 o Network topology (locations, connectivity, redundancy) 1533 o Subscriber billing information, and any of the above Subscriber 1534 information known to the provider. 1536 o Authentication credentials (such as certificates) 1538 Other organisations will have some combination of the lists above. 1539 The LMAP system would not typically expose all of the information 1540 above, but could expose a combination of items which could be 1541 correlated with other pieces collected by an attacker (as discussed 1542 in the section on Threats below). 1544 8.3. Different privacy issues raised by different sorts of Measurement 1545 Methods 1547 Measurement Methods raise different privacy issues depending on 1548 whether they measure traffic created specifically for that purpose, 1549 or whether they measure user traffic. 1551 Measurement Tasks conducted on user traffic store sensitive 1552 information, however briefly this storage may be. We note that some 1553 authorities make a distinction on time of storage, and information 1554 that is kept only temporarily to perform a communications function is 1555 not subject to regulation (for example, active queue management, deep 1556 packet inspection). Such Measurement Tasks could reveal all the 1557 websites a Subscriber visits and the applications and/or services 1558 they use. 1560 Other types of Measurement Task are conducted on traffic which is 1561 created specifically for the purpose. Even if a user host generates 1562 Measurement Traffic, there is limited sensitive information about the 1563 Subscriber present and stored in the measurement system: 1565 o IP address in use (and possibly sub-IP addresses and names) 1567 o Status as a study volunteer and Schedule of Measurement Tasks 1569 On the other hand, for a service provider the sensitive information 1570 like Measurement Results is the same for all Measurement Tasks. 1572 From the Subscriber perspective, both types of Measurement Task 1573 potentially expose the description of Internet access service and 1574 specific service parameters, such as subscribed rate and type of 1575 access. 1577 8.4. Privacy analysis of the Communications Models 1579 This section examines each of the protocol exchanges described at a 1580 high level in Section 5 and some example Measurement Tasks, and 1581 identifies specific sensitive information which must be secured 1582 during communication for each case. With the protocol-related 1583 sensitive information identified, we can better consider the threats 1584 described in the following section. 1586 From the privacy perspective, all entities participating in LMAP 1587 protocols can be considered "observers" according to the definition 1588 in [RFC6973]. Their stored information potentially poses a threat to 1589 privacy, especially if one or more of these functional entities has 1590 been compromised. Likewise, all devices on the paths used for 1591 control, reporting, and measurement are also observers. 1593 8.4.1. MA Bootstrapping 1595 Section 5.1 provides the communication model for the Bootstrapping 1596 process. 1598 Although the specification of mechanisms for Bootstrapping the MA are 1599 beyond the initial LMAP work scope, designers should recognize that 1600 the Bootstrapping process is extremely powerful and could cause an MA 1601 to join a new or different LMAP system with a different Controller 1602 and Collector, or simply install new Metrics with associated 1603 Measurement Methods (for example to record DNS queries). A Bootstrap 1604 attack could result in a breach of the LMAP system with significant 1605 sensitive information exposure depending on the capabilities of the 1606 MA, so sufficient security protections are warranted. 1608 The Bootstrapping process provides sensitive information about the 1609 LMAP system and the organisation that operates it, such as 1611 o Initial Controller IP address or FQDN 1613 o Assigned Controller IP address or FQDN 1615 o Security certificates and credentials 1617 During the Bootstrap process for an MA located at a single 1618 subscriber's service demarcation point, the MA receives a MA-ID which 1619 is a persistent pseudonym for the Subscriber. Thus, the MA-ID is 1620 considered sensitive information because it could provide the link 1621 between Subscriber identification and Measurements Results. 1623 Also, the Bootstrap process could assign a Group-ID to the MA. The 1624 specific definition of information represented in a Group-ID is to be 1625 determined, but several examples are envisaged including use as a 1626 pseudonym for a set of Subscribers, a class of service, an access 1627 technology, or other important categories. Assignment of a Group-ID 1628 enables anonymisation sets to be formed on the basis of service 1629 type/grade/rates. Thus, the mapping between Group-ID and MA-ID is 1630 considered sensitive information. 1632 8.4.2. Controller <-> Measurement Agent 1634 The high-level communication model for interactions between the LMAP 1635 Controller and Measurement Agent is illustrated in Section 5.2. The 1636 primary purpose of this exchange is to authenticate and task a 1637 Measurement Agent with Measurement Instructions, which the 1638 Measurement Agent then acts on autonomously. 1640 Primarily IP addresses and pseudonyms (MA-ID, Group-ID) are exchanged 1641 with a capability request, then measurement-related information of 1642 interest such as the parameters, schedule, metrics, and IP addresses 1643 of measurement devices. Thus, the measurement Instruction contains 1644 sensitive information which must be secured. For example, the fact 1645 that an ISP is running additional measurements beyond the set 1646 reported externally is sensitive information, as are the additional 1647 Measurements Tasks themselves. The Measurement Schedule is also 1648 sensitive, because an attacker intending to bias the results without 1649 being detected can use this information to great advantage. 1651 An organisation operating the Controller having no service 1652 relationship with a user who hosts the Measurement Agent *could* gain 1653 real-name mapping to a public IP address through user participation 1654 in an LMAP system (this applies to the Measurement Collection 1655 protocol, as well). 1657 8.4.3. Collector <-> Measurement Agent 1659 The high-level communication model for interactions between the 1660 Measurement Agent and Collector is illustrated in Section 5.4. The 1661 primary purpose of this exchange is to authenticate and collect 1662 Measurement Results from a MA, which the MA has measured autonomously 1663 and stored. 1665 The Measurement Results are the additional sensitive information 1666 included in the Collector-MA exchange. Organisations collecting LMAP 1667 measurements have the responsibility for data control. Thus, the 1668 Results and other information communicated in the Collector protocol 1669 must be secured. 1671 8.4.4. Measurement Peer <-> Measurement Agent 1673 A Measurement Method involving a Measurement Peer (or second 1674 Measurement Agent) raises potential privacy issues, although the 1675 specification of the mechanisms is beyond the scope of the initial 1676 LMAP work. The high-level communications model below illustrates the 1677 various exchanges to execute such a Measurement Method and store the 1678 Results. 1680 We note the potential for additional observers in the figures below 1681 by indicating the possible presence of a NAT, which has additional 1682 significance to the protocols and direction of initiation. 1684 The various messages are optional, depending on the nature of the 1685 Measurement Method. It may involve sending Measurement Traffic from 1686 the Measurement Peer to MA, MA to Measurement Peer, or both. 1687 Similarly, a second (or more) MAs may be involved. 1689 _________________ _________________ 1690 | | | | 1691 |Measurement Peer |=========== NAT ? ==========|Measurement Agent| 1692 |_________________| |_________________| 1694 <- (Key Negotiation & 1695 Encryption Setup) 1696 (Encrypted Channel -> 1697 Established) 1698 (Announce capabilities -> 1699 & status) 1700 <- (Select capabilities) 1701 ACK -> 1702 <- (Measurement Request 1703 (MA+MP IPAddrs,set of 1704 Metrics, Schedule)) 1705 ACK -> 1707 Measurement Traffic <> Measurement Traffic 1708 (may/may not be encrypted) (may/may not be encrypted) 1710 <- (Stop Measurement Task) 1712 Measurement Results -> 1713 (if applicable) 1714 <- ACK, Close 1716 This exchange primarily exposes the IP addresses of measurement 1717 devices and the inference of measurement participation from such 1718 traffic. There may be sensitive information on key points in a 1719 service provider's network included. There may also be access to 1720 measurement-related information of interest such as the Metrics, 1721 Schedule, and intermediate results carried in the Measurement Traffic 1722 (usually a set of timestamps). 1724 If the Measurement Traffic is unencrypted, as found in many systems 1725 today, then both timing and limited results are open to on-path 1726 observers. 1728 8.4.5. Measurement Agent 1730 Some Measurement Methods only involve a single Measurement Agent. 1731 They raise potential privacy issues, although the specification of 1732 the mechanisms is beyond the scope of the initial LMAP work. 1734 The high-level communications model below illustrates the collection 1735 of user information of interest with the Measurement Agent performing 1736 the monitoring and storage of the Results. This particular exchange 1737 is for measurement of DNS Response Time, which most frequently uses 1738 UDP transport. 1740 _________________ ____________ 1741 | | | | 1742 | DNS Server |=========== NAT ? ==========*=======| User client| 1743 |_________________| ^ |____________| 1744 ______|_______ 1745 | | 1746 | Measurement | 1747 | Agent | 1748 |______________| 1750 <- Name Resolution Req 1751 (MA+MP IPAddrs, 1752 Desired Domain Name) 1753 Return Record -> 1755 This exchange primarily exposes the IP addresses of measurement 1756 devices and the intent to communicate with or access the services of 1757 "Domain Name". There may be information on key points in a service 1758 provider's network, such as the address of one of its DNS servers. 1759 The Measurement Agent may be embedded in the user host, or it may be 1760 located in another device capable of observing user traffic. 1762 In principle, any of the user sensitive information of interest 1763 (listed above) can be collected and stored in the monitoring scenario 1764 and so must be secured. 1766 It would also be possible for a Measurement Agent to source the DNS 1767 query itself. But then there are few privacy concerns. 1769 8.4.6. Storage and Reporting of Measurement Results 1771 Although the mechanisms for communicating results (beyond the initial 1772 Collector) are beyond the initial LMAP work scope, there are 1773 potential privacy issues related to a single organisation's storage 1774 and reporting of Measurement Results. Both storage and reporting 1775 functions can help to preserve privacy by implementing the 1776 mitigations described below. 1778 8.5. Threats 1780 This section indicates how each of the threats described in [RFC6973] 1781 apply to the LMAP entities and their communication and storage of 1782 "information of interest". Denial of Service (DOS) and other attacks 1783 described in the Security section represent threats as well, and 1784 these attacks are more effective when sensitive information 1785 protections have been compromised. 1787 8.5.1. Surveillance 1789 Section 5.1.1 of [RFC6973] describes Surveillance as the "observation 1790 or monitoring of and individual's communications or activities." 1791 Hence all Measurement Methods that measure user traffic are a form of 1792 surveillance, with inherent risks. 1794 Measurement Methods which avoid periods of user transmission 1795 indirectly produce a record of times when a subscriber or authorised 1796 user has used their network access service. 1798 Measurement Methods may also utilise and store a Subscriber's 1799 currently assigned IP address when conducting measurements that are 1800 relevant to a specific Subscriber. Since the Measurement Results are 1801 time-stamped, they could provide a record of IP address assignments 1802 over time. 1804 Either of the above pieces of information could be useful in 1805 correlation and identification, described below. 1807 8.5.2. Stored Data Compromise 1809 Section 5.1.2 of [RFC6973] describes Stored Data Compromise as 1810 resulting from inadequate measures to secure stored data from 1811 unauthorised or inappropriate access. For LMAP systems this includes 1812 deleting or modifying collected measurement records, as well as data 1813 theft. 1815 The primary LMAP entity subject to compromise is the repository, 1816 which stores the Measurement Results; extensive security and privacy 1817 threat mitigations are warranted. The Collector and MA also store 1818 sensitive information temporarily, and need protection. The 1819 communications between the local storage of the Collector and the 1820 repository is beyond the scope of the initial LMAP work, though this 1821 communications channel will certainly need protection as well as the 1822 mass storage itself. 1824 The LMAP Controller may have direct access to storage of Subscriber 1825 information (location, billing, service parameters, etc.) and other 1826 information which the controlling organisation considers private, and 1827 again needs protection. 1829 Note that there is tension between the desire to store all raw 1830 results in the LMAP Collector (for reproducibility and custom 1831 analysis), and the need to protect the privacy of measurement 1832 participants. Many of the compromise mitigations described in 1833 section 8.6 below are most efficient when deployed at the MA, 1834 therefore minimising the risks with stored results. 1836 8.5.3. Correlation and Identification 1838 Sections 5.2.1 and 5.2.2 of [RFC6973] describe Correlation as 1839 combining various pieces of information to obtain desired 1840 characteristics of an individual, and Identification as using this 1841 combination to infer identity. 1843 The main risk is that the LMAP system could unwittingly provide a key 1844 piece of the correlation chain, starting with an unknown Subscriber's 1845 IP address and another piece of information. For example, a 1846 Subscriber utilised Internet access from 2000 to 2310 UTC, because 1847 the Measurement Tasks were deferred, or sent a name resolution for 1848 www.example.com at 2300 UTC. 1850 8.5.4. Secondary Use and Disclosure 1852 Sections 5.2.3 and 5.2.4 of [RFC6973] describes Secondary Use as 1853 unauthorised utilisation of an individual's information for a purpose 1854 the individual did not intend, and Disclosure is when such 1855 information is revealed causing other's notions of the individual to 1856 change, or confidentiality to be violated. 1858 Measurement Methods that measure user traffic are a form of Secondary 1859 Use, and the Subscribers' permission should be obtained beforehand. 1860 It may be necessary to obtain the measured ISP's permission to 1861 conduct measurements, for example when required by the terms and 1862 conditions of the service agreement, and notification is considered 1863 good measurement practice. 1865 For Measurement Methods that measure Measurement Traffic the 1866 Measurement Results provide some limited information about the 1867 Subscriber or ISP and could result in Secondary Uses. For example, 1868 the use of the Results in unauthorised marketing campaigns would 1869 qualify as Secondary Use. Secondary use may break national laws and 1870 regulations, and may violate individual's expectations or desires. 1872 8.6. Mitigations 1874 This section examines the mitigations listed in section 6 of 1875 [RFC6973] and their applicability to LMAP systems. Note that each 1876 section in [RFC6973] identifies the threat categories that each 1877 technique mitigates. 1879 8.6.1. Data Minimisation 1881 Section 6.1 of [RFC6973] encourages collecting and storing the 1882 minimal information needed to perform a task. 1884 LMAP results can be useful for general reporting about performance 1885 and for specific troubleshooting. They need different levels of 1886 information detail, as explained in the paragraphs below. 1888 For general results, the results can be aggregated into large 1889 categories (the month of March, all subscribers West of the 1890 Mississippi River). In this case, all individual identifications 1891 (including IP address of the MA) can be excluded, and only relevant 1892 results are provided. However, this implies a filtering process to 1893 reduce the information fields, because greater detail was needed to 1894 conduct the Measurement Tasks in the first place. 1896 For troubleshooting, so that a network operator or end user can 1897 identify a performance issue or failure, potentially all the network 1898 information (IP addresses, equipment IDs, location), Measurement 1899 Schedule, service configuration, Measurement Results, and other 1900 information may assist in the process. This includes the information 1901 needed to conduct the Measurements Tasks, and represents a need where 1902 the maximum relevant information is desirable, therefore the greatest 1903 protections should be applied. This level of detail is greater than 1904 needed for general performance monitoring. 1906 As regards Measurement Methods that measure user traffic, we note 1907 that a user may give temporary permission (to enable detailed 1908 troubleshooting), but withhold permission for them in general. Here 1909 the greatest breadth of sensitive information is potentially exposed, 1910 and the maximum privacy protection must be provided. The Collector 1911 may perform pre-storage minimisation and other mitigations (below) to 1912 help preserve privacy. 1914 For MAs with access to the sensitive information of users (e.g., 1915 within a home or a personal host/handset), it is desirable for the 1916 results collection to minimise the data reported, but also to balance 1917 this desire with the needs of troubleshooting when a service 1918 subscription exists between the user and organisation operating the 1919 measurements. 1921 8.6.2. Anonymity 1923 Section 6.1.1 of [RFC6973] describes a way in which anonymity is 1924 achieved: "there must exist a set of individuals that appear to have 1925 the same attributes as the individual", defined as an "anonymity 1926 set". 1928 Experimental methods for anonymisation of user identifiable data (and 1929 so particularly applicable to Measurement Methods that measure user 1930 traffic) have been identified in [RFC6235]. However, the findings of 1931 several of the same authors is that "there is increasing evidence 1932 that anonymisation applied to network trace or flow data on its own 1933 is insufficient for many data protection applications as in [Bur10]." 1934 Essentially, the details of such Measurement Methods can only be 1935 accessed by closed organisations, and unknown injection attacks are 1936 always less expensive than the protections from them. However, some 1937 forms of summary may protect the user's sensitive information 1938 sufficiently well, and so each Metric must be evaluated in the light 1939 of privacy. 1941 The techniques in [RFC6235] could be applied more successfully in 1942 Measurement Methods that generate Measurement Traffic, where there 1943 are protections from injection attack. The successful attack would 1944 require breaking the integrity protection of the LMAP Reporting 1945 Protocol and injecting Measurement Results (known fingerprint, see 1946 section 3.2 of [RFC6973]) for inclusion with the shared and 1947 anonymised results, then fingerprinting those records to ascertain 1948 the anonymisation process. 1950 Beside anonymisation of measured Results for a specific user or 1951 provider, the value of sensitive information can be further diluted 1952 by summarising the results over many individuals or areas served by 1953 the provider. There is an opportunity enabled by forming anonymity 1954 sets [RFC6973] based on the reference path measurement points in 1955 [I-D.ietf-ippm-lmap-path]. For example, all measurements from the 1956 Subscriber device can be identified as "mp000", instead of using the 1957 IP address or other device information. The same anonymisation 1958 applies to the Internet Service Provider, where their Internet 1959 gateway would be referred to as "mp190". 1961 8.6.3. Pseudonymity 1963 Section 6.1.2 of [RFC6973] indicates that pseudonyms, or nicknames, 1964 are a possible mitigation to revealing one's true identity, since 1965 there is no requirement to use real names in almost all protocols. 1967 A pseudonym for a measurement device's IP address could be an LMAP- 1968 unique equipment ID. However, this would likely be a permanent 1969 handle for the device, and long-term use weakens a pseudonym's power 1970 to obscure identity. 1972 8.6.4. Other Mitigations 1974 Data can be de-personalised by blurring it, for example by adding 1975 synthetic data, data-swapping, or perturbing the values in ways that 1976 can be reversed or corrected. 1978 Sections 6.2 and 6.3 of [RFC6973] describe User Participation and 1979 Security, respectively. 1981 Where LMAP measurements involve devices on the Subscriber's premises 1982 or Subscriber-owned equipment, it is essential to secure the 1983 Subscriber's permission with regard to the specific information that 1984 will be collected. The informed consent of the Subscriber (and, if 1985 different, the end user) may be needed, including the specific 1986 purpose of the measurements. The approval process could involve 1987 showing the Subscriber their measured information and results before 1988 instituting periodic collection, or before all instances of 1989 collection, with the option to cancel collection temporarily or 1990 permanently. 1992 It should also be clear who is legally responsible for data 1993 protection (privacy); in some jurisdictions this role is called the 1994 'data controller'. It is always good practice to limit the time of 1995 personal information storage. 1997 Although the details of verification would be impenetrable to most 1998 subscribers, the MA could be architected as an "app" with open 1999 source-code, pre-download and embedded terms of use and agreement on 2000 measurements, and protection from code modifications usually provided 2001 by the app-stores. Further, the app itself could provide data 2002 reduction and temporary storage mitigations as appropriate and 2003 certified through code review. 2005 LMAP protocols, devices, and the information they store clearly need 2006 to be secure from unauthorised access. This is the hand-off between 2007 privacy and security considerations (Section 7). The Data Controller 2008 has the (legal) responsibility to maintain data protections described 2009 in the Subscriber's agreement and agreements with other 2010 organisations. 2012 9. IANA Considerations 2014 There are no IANA considerations in this memo. 2016 10. Appendix: Deployment examples 2018 In this section we describe some deployment scenarios that are 2019 feasible within the LMAP framework defined in this document. 2021 The LMAP framework defines two types of components involved in the 2022 actual measurement task, namely the Measurement Agent (MA) and the 2023 Measurement Peer (MP). The fundamental difference conveyed in the 2024 definition of these terms is that the MA has a interface with the 2025 Controller/Collector while the MP does not. The MP is broadly 2026 defined as a function that assists the MA in the Measurement Task but 2027 has no interface with the Controller/Collector. There are many 2028 elements in the network that can fall into this broad definition of 2029 MP. We believe that the MP terminology is useful to allow us to 2030 refer an element of the network that plays a role that is 2031 conceptually important to understand and describe the measurement 2032 task being performed. We next illustrate these concepts by 2033 describing several deployment scenarios. 2035 A very simple example of a Measurement Peer is a web server that the 2036 MA is downloading a web page from (such as www.example.com) in order 2037 to perform a speed test. The web server is a MP and from its 2038 perspective, the MA is just another client; the MP doesn't have a 2039 specific function for assisting measurements. This is described in 2040 the figure A1. 2042 ^ 2043 +----------------+ Web Traffic +----------------+ IPPM 2044 | Web Client |<------------>| MP: Web Server | Scope 2045 | | +----------------+ | 2046 ...|................|....................................V... 2047 | LMAP interface | ^ 2048 +----------------+ | 2049 ^ | | 2050 Instruction | | Report | 2051 | +-----------------+ | 2052 | | | 2053 | v LMAP 2054 +------------+ +------------+ Scope 2055 | Controller | | Collector | | 2056 +------------+ +------------+ V 2058 Figure A1: Schematic of LMAP-based measurement system, 2059 with Web server as Measurement Peer 2061 Another case that is slightly different than this would be the one of 2062 a TWAMP-responder. This is also a MP, with a helper function, the 2063 TWAMP server, which is specially deployed to assist the MAs that 2064 perform TWAMP tests. Another example is with a ping server, as 2065 described in Section 2. 2067 A further example is the case of a traceroute like measurement. In 2068 this case, for each packet sent, the router where the TTL expires is 2069 performing the MP function. So for a given Measurement Task, there 2070 is one MA involved and several MPs, one per hop. 2072 In figure A2 we depict the case of an OWAMP responder acting as an 2073 MP. In this case, the helper function in addition reports results 2074 back to the MA. So it has both a data plane and control interface 2075 with the MA. 2077 +----------------+ OWAMP +----------------+ ^ 2078 | OWAMP |<--control--->| MP: | | 2079 | control-client |>test-traffic>| OWAMP server & | IPPM 2080 | fetch-client & |<----fetch----| session-rec'ver| Scope 2081 | session-sender | | | | 2082 | | +----------------+ | 2083 ...|................|....................................v... 2084 | LMAP interface | ^ 2085 +----------------+ | 2086 ^ | | 2087 Instruction | | Report | 2088 | +-----------------+ | 2089 | | | 2090 | v LMAP 2091 +------------+ +------------+ Scope 2092 | Controller | | Collector | | 2093 +------------+ +------------+ v 2094 IPPM 2096 Figure A2: Schematic of LMAP-based measurement system, 2097 with OWAMP server as Measurement Peer 2099 However, it is also possible to use two Measurement Agents when 2100 performing one way Measurement Tasks, as described in figure A3 2101 below. In this case, MA1 generates the traffic and MA2 receives the 2102 traffic and send the reports to the Collector. Note that both MAs 2103 are instructed by the Controller. MA1 receives an Instruction to 2104 send the traffic and MA2 receives an Instruction to measured the 2105 received traffic and send Reports to the Collector. 2107 +----------------+ +----------------+ ^ 2108 | MA1 | | MA2 | IPPM 2109 | iperf -u sender|-UDP traffic->| iperf -u recvr | Scope 2110 | | | | v 2111 ...|................|..............|................|....v... 2112 | LMAP interface | | LMAP interface | ^ 2113 +----------------+ +----------------+ | 2114 ^ ^ | | 2115 Instruction | Instruction{Report} | | Report | 2116 {task, | +-------------------+ | | 2117 schedule} | | | | 2118 | | v LMAP 2119 +------------+ +------------+ Scope 2120 | Controller | | Collector | | 2121 +------------+ +------------+ v 2122 IPPM 2124 Figure A3: Schematic of LMAP-based measurement system, 2125 with two Measurement Agents cooperating to measure UDP traffic 2127 Next, we consider Measurement Methods that measure user traffic. 2128 Traffic generated in one point in the network flowing towards a given 2129 destination and the traffic is observed in some point along the path. 2130 One way to implement this is that the endpoints generating and 2131 receiving the traffic are not instructed by the Controller; hence 2132 they are MPs. The MA is located along the path with a monitor 2133 function that measures the traffic. The MA is instructed by the 2134 Controller to monitor that particular traffic and to send the Report 2135 to the Collector. It is depicted in figure A4 below. 2137 +-----+ +----------------+ +------+ ^ 2138 | MP | | MA: Monitor | | MP | IPPM 2139 | |<--|----------------|---traffic--->| | Scope 2140 +-----+ | | +------+ | 2141 .......|................|.........................v........... 2142 | LMAP interface | ^ 2143 +----------------+ | 2144 ^ | | 2145 Instruction | | Report | 2146 | +-----------------+ | 2147 | | | 2148 | v LMAP 2149 +------------+ +------------+ Scope 2150 | Controller | | Collector | | 2151 +------------+ +------------+ v 2153 Figure A4: Schematic of LMAP-based measurement system, 2154 with a Measurement Agent monitoring traffic 2156 Finally, we should consider the case of a router or a switch along 2157 the measurement path. This certainly performs an important role in 2158 the measurement - if packets are not forwarded, the measurement task 2159 will not work. Whilst it doesn't has an interface with the 2160 Controller or Collector, and so fits into the definition of MP, 2161 usually it is not particularly useful to highlight it as a MP. 2163 11. Acknowledgments 2165 This document is a merger of three individual drafts: draft-eardley- 2166 lmap-terminology-02, draft-akhter-lmap-framework-00, and draft- 2167 eardley-lmap-framework-02. 2169 Thanks to Juergen Schoenwaelder for his detailed review of the 2170 terminology. Thanks to Charles Cook for a very detailed review of 2171 -02. Thanks to Barbara Stark and Ken Ko for many helpful comments 2172 about later versions. 2174 Thanks to numerous people for much discussion, directly and on the 2175 LMAP list (apologies to those unintentionally omitted): Alan Clark, 2176 Alissa Cooper, Andrea Soppera, Barbara Stark, Benoit Claise, Brian 2177 Trammell, Charles Cook, Dave Thorne, Frode Soerensen, Greg Mirsky, 2178 Guangqing Deng, Jason Weil, Jean-Francois Tremblay, Jerome Benoit, 2179 Joachim Fabini, Juergen Schoenwaelder, Jukka Manner, Ken Ko, Lingli 2180 Deng, Mach Chen, Marc Ibrahim, Michael Bugenhagen, Michael Faath, 2181 Nalini Elkins, Rolf Winter, Sam Crawford, Sharam Hakimi, Steve 2182 Miller, Ted Lemon, Timothy Carey, Vaibhav Bajpai, Vero Zheng, William 2183 Lupton. 2185 Philip Eardley, Trevor Burbridge and Marcelo Bagnulo work in part on 2186 the Leone research project, which receives funding from the European 2187 Union Seventh Framework Programme [FP7/2007-2013] under grant 2188 agreement number 317647. 2190 12. History 2192 First WG version, copy of draft-folks-lmap-framework-00. 2194 12.1. From -00 to -01 2196 o new sub-section of possible use of Group-IDs for privacy 2198 o tweak to definition of Control protocol 2200 o fix typo in figure in S5.4 2202 12.2. From -01 to -02 2204 o change to INFORMATIONAL track (previous version had typo'd 2205 Standards track) 2207 o new definitions for Capabilities Information and Failure 2208 Information 2210 o clarify that diagrams show LMAP-level information flows. 2211 Underlying protocol could do other interactions, eg to get through 2212 NAT or for Collector to pull a Report 2214 o add hint that after a re-boot should pause random time before re- 2215 register (to avoid mass calling event) 2217 o delete the open issue "what happens if a Controller fails" (normal 2218 methods can handle) 2220 o add some extra words about multiple Tasks in one Schedule 2222 o clarify that new Schedule replaces (rather than adds to) and old 2223 one. Similarly for new configuration of Measurement Tasks or 2224 Report Channels. 2226 o clarify suppression is temporary stop; send a new Schedule to 2227 permanently stop Tasks 2229 o alter suppression so it is ACKed 2231 o add un-suppress message 2232 o expand the text on error reporting, to mention Reporting failures 2233 (as well as failures to action or execute Measurement Task & 2234 Schedule) 2236 o add some text about how to have Tasks running indefinitely 2238 o add that optionally a Report is not sent when there are no 2239 Measurement Results 2241 o add that a Measurement Task may create more than one Measurement 2242 Result 2244 o clarify /amend /expand that Reports include the "raw" Measurement 2245 Results - any pre-processing is left for lmap2.0 2247 o add some cautionary words about what if the Collector unexpectedly 2248 doesn't hear from a MA 2250 o add some extra words about the potential impact of Measurement 2251 Tasks 2253 o clarified various aspects of the privacy section 2255 o updated references 2257 o minor tweaks 2259 12.3. From -02 to -03 2261 o alignment with the Information Model [burbridge-lmap-information- 2262 model] as this is agreed as a WG document 2264 o One-off and periodic Measurement Schedules are kept separate, so 2265 that they can be updated independently 2267 o Measurement Suppression in a separate sub-section. Can now 2268 optionally include particular Measurement Tasks &/or Schedules to 2269 suppress, and start/stop time 2271 o for clarity, concept of Channel split into Control, Report and MA- 2272 to-Controller Channels 2274 o numerous editorial changes, mainly arising from a very detailed 2275 review by Charles Cook 2277 o 2279 12.4. From -03 to -04 2281 o updates following the WG Last Call, with the proposed consensus on 2282 the various issues as detailed in 2283 http://tools.ietf.org/agenda/89/slides/slides-89-lmap-2.pdf. In 2284 particular: 2286 o tweaked definitions, especially of Measurement Agent and 2287 Measurement Peer 2289 o Instruction - left to each implementation & deployment of LMAP to 2290 decide on the granularity at which an Instruction Message works 2292 o words added about overlapping Measurement Tasks (measurement 2293 system can handle any way they choose; Report should mention if 2294 the Task overlapped with another) 2296 o Suppression: no defined impact on Passive Measurement Task; extra 2297 option to suppress on-going Active Measurement Tasks; suppression 2298 doesn't go to Measurement Peer, since they don't understand 2299 Instructions 2301 o new concept of Data Transfer Task (and therefore adjustment of the 2302 Channel concept) 2304 o enhancement of Results with Subscriber's service parameters - 2305 could be useful, don't define how but can be included in Report to 2306 various other sections 2308 o various other smaller improvements, arising from the WGLC 2310 o Appendix added with examples of Measurement Agents and Peers in 2311 various deployment scenarios. To help clarify what these terms 2312 mean. 2314 12.5. From -04 to -05 2316 o clarified various scoping comments by using the phrase "scope of 2317 initial LMAP work" (avoiding "scope of LMAP WG" since this may 2318 change in the future) 2320 o added a Configuration Protocol - allows the Controller to update 2321 the MA about information that it obtained during the bootstrapping 2322 process (for consistency with Information Model) 2324 o Removed over-detailed information about the relationship between 2325 the different items in Instruction, as this seems more appropriate 2326 for the information model. Clarified that the lists given are 2327 about the aims and not a list of information elements (these will 2328 be defined in draft-ietf-information-model). 2330 o the Measurement Method, specified as a URI to a registry entry - 2331 rather than a URN 2333 o MA configured with time limit after which, if it hasn't heard from 2334 Controller, then it stops running Measurement Tasks (rather than 2335 this being part of a Schedule) 2337 o clarified there is no distinction between how capabilities, 2338 failure and logging information are transferred (all can be when 2339 requested by Controller or by MA on its own initiative). 2341 o removed mention of Data Transfer Tasks. This abstraction is left 2342 to the information model i-d 2344 o added Deployment sub-section about Measurement Agent embedded in 2345 ISP Network 2347 o various other smaller improvements, arising from the 2nd WGLC 2349 12.6. From -05 to -06 2351 o clarified terminlogy around Measurement Methods and Tasks. Since 2352 within a Method there may be several different roles (requester 2353 and responder, for instance) 2355 o Suppression: there is now the concept of a flag (boolean) which 2356 indicates whether a Task is by default gets suppressed or not. 2357 The optional suppression message (with list of specific tasks 2358 /schedules to suppress) over-rides this flag. 2360 o The previous bullet also means there is no need to make a 2361 distinction between active and passive Measurement Tasks, so this 2362 distinction is removed. 2364 o removed Configuration Protocol - Configuration is part of the 2365 Instruction and so uses the Control Protocol. 2367 12.7. From -06 to -07 2369 o Clarifications and nits 2371 13. Informative References 2373 [Bur10] Burkhart, M., Schatzmann, D., Trammell, B., and E. Boschi, 2374 "The Role of Network Trace anonymisation Under Attack", 2375 January 2010. 2377 [TR-069] TR-069, , "CPE WAN Management Protocol", 2378 http://www.broadband-forum.org/technical/trlist.php, 2379 November 2013. 2381 [UPnP] ISO/IEC 29341-x, , "UPnP Device Architecture and UPnP 2382 Device Control Protocols specifications", 2383 http://upnp.org/sdcps-and-certification/standards/, 2011. 2385 [RFC1035] Mockapetris, P., "Domain names - implementation and 2386 specification", STD 13, RFC 1035, November 1987. 2388 [RFC4101] Rescorla, E. and IAB, "Writing Protocol Models", RFC 4101, 2389 June 2005. 2391 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 2392 Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2393 2005. 2395 [I-D.ietf-lmap-use-cases] 2396 Linsner, M., Eardley, P., Burbridge, T., and F. Sorensen, 2397 "Large-Scale Broadband Measurement Use Cases", draft-ietf- 2398 lmap-use-cases-03 (work in progress), April 2014. 2400 [I-D.manyfolks-ippm-metric-registry] 2401 Bagnulo, M., Claise, B., Eardley, P., and A. Morton, 2402 "Registry for Performance Metrics", draft-manyfolks-ippm- 2403 metric-registry-00 (work in progress), February 2014. 2405 [I-D.ietf-homenet-arch] 2406 Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil, 2407 "IPv6 Home Networking Architecture Principles", draft- 2408 ietf-homenet-arch-16 (work in progress), June 2014. 2410 [RFC6419] Wasserman, M. and P. Seite, "Current Practices for 2411 Multiple-Interface Hosts", RFC 6419, November 2011. 2413 [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. 2414 Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 2415 2013. 2417 [I-D.ietf-lmap-information-model] 2418 Burbridge, T., Eardley, P., Bagnulo, M., and J. 2419 Schoenwaelder, "Information Model for Large-Scale 2420 Measurement Platforms (LMAP)", draft-ietf-lmap- 2421 information-model-00 (work in progress), February 2014. 2423 [RFC6235] Boschi, E. and B. Trammell, "IP Flow Anonymization 2424 Support", RFC 6235, May 2011. 2426 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 2427 Morris, J., Hansen, M., and R. Smith, "Privacy 2428 Considerations for Internet Protocols", RFC 6973, July 2429 2013. 2431 [I-D.ietf-ippm-lmap-path] 2432 Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and 2433 A. Morton, "A Reference Path and Measurement Points for 2434 LMAP", draft-ietf-ippm-lmap-path-04 (work in progress), 2435 June 2014. 2437 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. 2438 Zekauskas, "A One-way Active Measurement Protocol 2439 (OWAMP)", RFC 4656, September 2006. 2441 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 2442 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 2443 RFC 5357, October 2008. 2445 [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between 2446 Information Models and Data Models", RFC 3444, January 2447 2003. 2449 Authors' Addresses 2451 Philip Eardley 2452 BT 2453 Adastral Park, Martlesham Heath 2454 Ipswich 2455 ENGLAND 2457 Email: philip.eardley@bt.com 2458 Al Morton 2459 AT&T Labs 2460 200 Laurel Avenue South 2461 Middletown, NJ 2462 USA 2464 Email: acmorton@att.com 2466 Marcelo Bagnulo 2467 Universidad Carlos III de Madrid 2468 Av. Universidad 30 2469 Leganes, Madrid 28911 2470 SPAIN 2472 Phone: 34 91 6249500 2473 Email: marcelo@it.uc3m.es 2474 URI: http://www.it.uc3m.es 2476 Trevor Burbridge 2477 BT 2478 Adastral Park, Martlesham Heath 2479 Ipswich 2480 ENGLAND 2482 Email: trevor.burbridge@bt.com 2484 Paul Aitken 2485 Cisco Systems, Inc. 2486 96 Commercial Street 2487 Edinburgh, Scotland EH6 6LX 2488 UK 2490 Email: paitken@cisco.com 2492 Aamer Akhter 2493 Cisco Systems, Inc. 2494 7025 Kit Creek Road 2495 RTP, NC 27709 2496 USA 2498 Email: aakhter@cisco.com