<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes" ?>
<?rfc compact="yes"?>
<?rfc text-list-symbols="o*+-"?>
<rfc category="info" docName="draft-ietf-lmap-framework-07" ipr="trust200902"
     obsoletes="" updates="">
  <front>
    <title abbrev="LMAP Framework">A framework for large-scale measurement
    platforms (LMAP)</title>

    <author fullname="Philip Eardley" initials="P." surname="Eardley">
      <organization abbrev="BT">BT</organization>

      <address>
        <postal>
          <street>Adastral Park, Martlesham Heath</street>

          <city>Ipswich</city>

          <country>ENGLAND</country>
        </postal>

        <email>philip.eardley@bt.com</email>
      </address>
    </author>

    <author fullname="Al Morton" initials="A." surname="Morton">
      <organization abbrev="AT&amp;T Labs">AT&amp;T Labs</organization>

      <address>
        <postal>
          <street>200 Laurel Avenue South</street>

          <city>Middletown, NJ</city>

          <country>USA</country>
        </postal>

        <email>acmorton@att.com</email>
      </address>
    </author>

    <author fullname="Marcelo Bagnulo" initials="M." surname="Bagnulo">
      <organization abbrev="UC3M">Universidad Carlos III de
      Madrid</organization>

      <address>
        <postal>
          <street>Av. Universidad 30</street>

          <city>Leganes</city>

          <region>Madrid</region>

          <code>28911</code>

          <country>SPAIN</country>
        </postal>

        <phone>34 91 6249500</phone>

        <email>marcelo@it.uc3m.es</email>

        <uri>http://www.it.uc3m.es</uri>
      </address>
    </author>

    <author fullname="Trevor Burbridge" initials="T." surname="Burbridge">
      <organization abbrev="BT">BT</organization>

      <address>
        <postal>
          <street>Adastral Park, Martlesham Heath</street>

          <city>Ipswich</city>

          <country>ENGLAND</country>
        </postal>

        <email>trevor.burbridge@bt.com</email>
      </address>
    </author>

    <author fullname="Paul Aitken" initials="P." surname="Aitken">
      <organization abbrev="Cisco Systems">Cisco Systems, Inc.</organization>

      <address>
        <postal>
          <street>96 Commercial Street</street>

          <city>Edinburgh</city>

          <region>Scotland</region>

          <code>EH6 6LX</code>

          <country>UK</country>
        </postal>

        <email>paitken@cisco.com</email>
      </address>
    </author>

    <author fullname="Aamer Akhter" initials="A." surname="Akhter">
      <organization abbrev="Cisco Systems">Cisco Systems, Inc.</organization>

      <address>
        <postal>
          <street>7025 Kit Creek Road</street>

          <city>RTP</city>

          <region>NC</region>

          <code>27709</code>

          <country>USA</country>
        </postal>

        <email>aakhter@cisco.com</email>
      </address>
    </author>

    <date day="24" month="June" year="2014"/>

    <abstract>
      <t>Measuring broadband service on a large scale requires a description
      of the logical architecture and standardisation of the key protocols
      that coordinate interactions between the components. The document
      presents an overall framework for large-scale measurements. It also
      defines terminology for LMAP (large-scale measurement platforms).</t>
    </abstract>
  </front>

  <middle>
    <section title="Introduction">
      <t>There is a desire to be able to coordinate the execution of broadband
      measurements and the collection of measurement results across a large
      scale set of diverse devices. These devices could be software based
      agents on PCs, embedded agents in consumer devices (e.g. Blu-ray
      players), service provider controlled devices such as set-top boxes and
      home gateways, or simply dedicated probes. It is expected that such a
      system could easily comprise 100,000 devices. Measurement devices may
      also be embedded on a device that is part of an ISP's network, such as a
      DSLAM, router, Carrier Grade NAT or ISP Gateway. Such a scale presents
      unique problems in coordination, execution and measurement result
      collection. Several use cases have been proposed for large-scale
      measurements including:</t>

      <t><list style="symbols">
          <t>Operators: to help plan their network and identify faults</t>

          <t>Regulators: to benchmark several network operators and support
          public policy development</t>
        </list>Further details of the use cases can be found in <xref
      target="I-D.ietf-lmap-use-cases"/>. The LMAP framework should be useful
      for these, as well as other use cases, such as to help end users run
      diagnostic checks like a network speed test.</t>

      <t>The LMAP Framework has three basic elements: Measurement Agents,
      Controllers and Collectors.</t>

      <t>Measurement Agents (MAs) initiate the actual measurements, which are
      called Measurement Tasks in the LMAP terminology. In principle, there
      are no restrictions on the type of device in which the MA function
      resides.</t>

      <t>The Controller instructs one or more MAs and communicates the set of
      Measurement Tasks an MA should perform and when. For example it may
      instruct a MA at a home gateway: &ldquo;Measure the &lsquo;UDP
      latency&rsquo; with www.example.org; repeat every hour at xx.05&rdquo;.
      The Controller also manages a MA by instructing it how to report the
      Measurement Results, for example: &ldquo;Report results once a day in a
      batch at 4am&rdquo;. We refer to these as the Measurement Schedule and
      Report Schedule.</t>

      <t>The Collector accepts Reports from the MAs with the Results from
      their Measurement Tasks. Therefore the MA is a device that gets
      Instructions from the Controller, initiates the Measurement Tasks, and
      reports to the Collector. The communications between these three LMAP
      functions are structured according to a Control Protocol and a Report
      Protocol.</t>

      <t>The desirable features for a large-scale measurement systems we are
      designing for are:</t>

      <t><list style="symbols">
          <t>Standardised - in terms of the Measurement Tasks that they
          perform, the components, the data models and protocols for
          transferring information between the components. Amongst other
          things, standardisation enables meaningful comparisons of
          measurements made of the same metric at different times and places,
          and provides the operator of a measurement system with criteria for
          evaluation of the different solutions that can be used for various
          purposes including buying decisions (such as buying the various
          components from different vendors). Today's systems are proprietary
          in some or all of these aspects.</t>

          <t>Large-scale - <xref target="I-D.ietf-lmap-use-cases"/> envisages
          Measurement Agents in every home gateway and edge device such as
          set-top boxes and tablet computers, and located throughout the
          Internet as well <xref target="I-D.ietf-ippm-lmap-path"/>. It is
          expected that a measurement system could easily encompass a few
          hundred thousand or even millions of Measurement Agents. Existing
          systems have up to a few thousand MAs (without judging how much
          further they could scale).</t>

          <t>Diversity - a measurement system should handle different types of
          Measurement Agents - for example Measurement Agents may come from
          different vendors, be in wired and wireless networks, be able to
          execute different sorts of Measurement Task and be on devices with
          IPv4 or IPv6 addresses.</t>
        </list></t>
    </section>

    <section title="Outline of an LMAP-based measurement system">
      <t>Figure 1 shows the main components of a measurement system, and the
      interactions of those components. Some of the components are outside the
      scope of initial LMAP work. In this section we provide an overview of
      the whole measurement system and we introduce the main terms needed for
      the LMAP framework. The new terms are capitalised. In the next section
      we provide a terminology section with a compilation of all the LMAP
      terms and their definition. Section 4 onwards considers the LMAP
      components in more detail.</t>

      <t>Other LMAP specifications will define an information model, the
      associated data models, and select/extend one or more protocols for the
      secure communication: firstly, a Control Protocol, from a Controller to
      instruct Measurement Agents what performance metrics to measure, when to
      measure them, how/when to report the measurement results to a Collector;
      secondly, a Report Protocol, for a Measurement Agent to report the
      results to the Collector.</t>

      <t>The MA performs Measurement Tasks. The MAs are pieces of code that
      can be executed in specialised hardware (hardware probe) or on a
      general-purpose device (like a PC or mobile phone). The MA may generate
      Measurement Traffic and measure some metric associated with its
      transfer, or the MA may observe existing traffic, or there may be some
      kind of hybrid of these two possibilities. A device with a Measurement
      Agent may have multiple physical interfaces (Wi-Fi, Ethernet, DSL,
      fibre; and non-physical interfaces such as PPPoE or IPsec) and the
      Measurement Tasks may specify any one of these.</t>

      <t>The Controller manages a MA through use of the Control Protocol,
      which transfers the Instruction to the MA. This describes the
      Measurement Tasks the MA should perform and when. For example the
      Controller may instruct a MA at a home gateway: &ldquo;Count the number
      of TCP SYN packets observed in a 1 minute interval; repeat every hour at
      xx.05 + Unif[0,180] seconds&rdquo;. The Measurement Schedule determines
      when the Measurement Tasks are executed. The Controller also manages a
      MA by instructing it how to report the Measurement Results, for example:
      &ldquo;Report results once a day in a batch at 4am + Unif[0,180]
      seconds; if the end user is active then delay the report 5
      minutes&rdquo;. The Report Schedule determines when the Reports are
      uploaded to the Collector. The Measurement Schedule and Report Schedule
      can define one-off (non-recurring) actions ("Do measurement now",
      "Report as soon as possible"), as well as recurring ones.</t>

      <t>The Collector accepts a Report from a MA with the Measurement Results
      from its Measurement Tasks. It then provides the Results to a repository
      (see below).</t>

      <t>A Measurement Method defines how to measure a Metric of interest. It
      is very useful to standardise Measurement Methods, so that it is
      meaningful to compare measurements of the same Metric made at different
      times and places. It is also useful to define a registry for
      commonly-used Metrics <xref
      target="I-D.manyfolks-ippm-metric-registry"/> so that a Metric with its
      associated Measurement Method can be referred to simply by its
      identifier in the registry. The Measurement Methods and registry will
      hopefully be referenced by other standards organisations.</t>

      <t>Broadly speaking there are two types of Measurement Method. It may
      involve a single MA simply observing existing traffic - for example, the
      Measurement Agent could count bytes or calculate the average loss for a
      particular flow. On the other hand, a Measurement Method may involve
      multiple network entities, which perform different roles. For example, a
      "ping" Measurement Method, to measure the round trip delay , would
      consist of an MA sending an ICMP ECHO request to a responder in the
      Internet. In LMAP terms, the responder is termed a Measurement Peer
      (MP), meaning that it helps the MA but is not managed by the Controller.
      Other Measurement Methods involve a second MA, with the Controller
      instructing the MAs in a coordinated manner. Traffic generated
      specifically as part of the Measurement Method is termed Measurement
      Traffic; in the ping example, it is the ICMP ECHO Requests and Replies.
      The protocols used for the Measurement Traffic are out of the scope of
      initial LMAP work, and fall within the scope of other IETF WGs such as
      IPPM. The Appendix has some other examples of possible arrangements of
      Measurement Agents and Peers.</t>

      <t>A Measurement Task is the action performed by a particular MA at a
      particular time, as the specific instance of its role in a Measurement
      Method. LMAP is mainly concerned with Measurement Tasks, for instance in
      terms of its Information Model and Protocols.</t>

      <t>For Measurement Results to be truly comparable, as might be required
      by a regulator, not only do the same Measurement Methods need to be used
      to assess Metrics, but also the set of Measurement Tasks should follow a
      similar Measurement Schedule and be of similar number. The details of
      such a characterisation plan are beyond the scope of work in IETF
      although certainly facilitated by IETF's work.</t>

      <t>Messages are transferred over a secure Channel. A Control Channel is
      between the Controller and a MA; the Control Protocol delivers
      Instruction Messages to the MA and Capabilities, Failure and Logging
      Information in the reverse direction. A Report Channel is between a MA
      and Collector, and the Report Protocol delivers Reports to the
      Collector.</t>

      <t>Finally we introduce several components that are outside the scope of
      initial LMAP work and will be provided through existing protocols or
      applications. They affect how the measurement system uses the
      Measurement Results and how it decides what set of Measurement Tasks to
      perform.</t>

      <t>The MA needs to be bootstrapped with initial details about its
      Controller, including authentication credentials. The LMAP work
      considers the bootstrap process, since it affects the Information Model.
      However, LMAP does not define a bootstrap protocol, since it is likely
      to be technology specific and could be defined by the Broadband Forum,
      CableLabs or IEEE depending on the device. Possible protocols are SNMP,
      NETCONF or (for Home Gateways) CPE WAN Management Protocol (CWMP) from
      the Auto Configuration Server (ACS) (as specified in TR-069 <xref
      target="TR-069"/>).</t>

      <t>A Subscriber parameter database contains information about the line,
      such as the customer's broadband contract (perhaps 2, 40 or 80Mb/s), the
      line technology (DSL or fibre), the time zone where the MA is located,
      and the type of home gateway and MA. These parameters are already
      gathered and stored by existing operations systems. They may affect the
      choice of what Measurement Tasks to run and how to interpret the
      Measurement Results. For example, a download test suitable for a line
      with an 80Mb/s contract may overwhelm a 2Mb/s line.</t>

      <t>A results repository records all Measurement Results in an equivalent
      form, for example an SQL database, so that they can easily be accessed
      by the data analysis tools.</t>

      <t>The data analysis tools receive the results from the Collector or via
      the Results repository. They might visualise the data or identify which
      component or link is likely to be the cause of a fault or degradation.
      This information could help the Controller decide what follow-up
      Measurement Task to perform in order to diagnose a fault. The data
      analysis tools also need to understand the Subscriber's service
      information, for example the broadband contract.</t>

      <t/>

      <figure>
        <artwork><![CDATA[                                                              ^
                                                              |
                                           +-------------+    IPPM
            +---------------+  Measurement | Measurement |    Scope
            | Measurement   |<------------>|     Peer    |    |
            |   Agent       |   Traffic    +-------------+    v
   +------->|               |                                 ^
   |        +---------------+                                 |
   |              ^      |                                    |
   |  Instruction |      |  Report                            |
   |              |      +-----------------+                  |
   |              |                        |                  |
   |              |                        v                  LMAP
   |         +------------+             +------------+        Scope
   |         | Controller |             |  Collector |        |
   |         +------------+             +------------+        v
   |                ^   ^                       |             ^
   |                |   |                       |             |
   |                |   +----------+            |             |
   |                |              |            v             |
+------------+   +----------+    +--------+    +----------+   | 
|Bootstrapper|   |Subscriber|--->|  data  |<---|repository|   Out
+------------+   |parameter |    |analysis|    +----------+   of
                 |database  |    | tools  |                   Scope
                 +----------+    +--------+                   |  
                                                              |
                                                              v

Figure 1: Schematic of main elements of an LMAP-based 
measurement system
(showing the elements in and out of the scope of initial LMAP work)
]]></artwork>
      </figure>
    </section>

    <section title="Terminology">
      <t>This section defines terminology for LMAP. Please note that defined
      terms are capitalized.</t>

      <t>Bootstrap: A process that integrates a Measurement Agent into a
      measurement system.</t>

      <t>Capabilities: Information about the performance measurement
      capabilities of the MA, in particular the Measurement Method roles and
      measurement protocol roles that it can perform, and the device hosting
      the MA, for example its interface type and speed, but not dynamic
      information.</t>

      <t>Channel: A bi-directional logical connection that is defined by a
      specific Controller and MA, or Collector and MA, plus associated
      security.</t>

      <t>Collector: A function that receives a Report from a Measurement
      Agent.</t>

      <t>Controller: A function that provides a Measurement Agent with its
      Instruction.</t>

      <t>Control Channel: a Channel between a Controller and a MA over which
      Instruction Messages and Capabilities, Failure and Logging Information
      are sent.</t>

      <t>Control Protocol: The protocol delivering Instruction(s) from a
      Controller to a Measurement Agent. It also delivers Capabilities,
      Failure and Logging Information from the Measurement Agent to the
      Controller. It can also be used to update the MA's configuration.</t>

      <t>Cycle-ID: A tag that is sent by the Controller in an Instruction and
      echoed by the MA in its Report. The same Cycle-ID is used by several MAs
      that use the same Measurement Method for a Metric with the same Input
      Parameters. Hence the Cycle-ID allows the Collector to easily identify
      Measurement Results that should be comparable.</t>

      <t>Data Model: The implementation of an Information Model in a
      particular data modelling language <xref target="RFC3444"/>.</t>

      <t>Environmental Constraint: A parameter that is measured as part of the
      Measurement Task, its value determining whether the rest of the
      Measurement Task proceeds.</t>

      <t>Failure Information: Information about the MA's failure to action or
      execute an Instruction, whether concerning Measurement Tasks or
      Reporting.</t>

      <t>Group-ID: An identifier of a group of MAs.</t>

      <t>Information Model: The protocol-neutral definition of the semantics
      of the Instructions, the Report, the status of the different elements of
      the measurement system as well of the events in the system <xref
      target="RFC3444"/>.</t>

      <t>Input Parameter: A parameter whose value is left open by the Metric
      and its Measurement Method and is set to a specific value in a
      Measurement Task. Altering the value of an Input Parameter does not
      change the fundamental nature of the Measurement Task.</t>

      <t>Instruction: The description of Measurement Tasks for a MA to perform
      and the details of the Report for it to send. It is the collective
      description of the Measurement Task configurations, the configuration of
      the Measurement Schedules, the configuration of the Report Channel(s),
      the configuration of Report Schedule(s), and the details of any
      suppression.</t>

      <t>Instruction Message: The message that carries an Instruction from a
      Controller to a Measurement Agent.</t>

      <t>Logging Information: Information about the operation of the
      Measurement Agent and which may be useful for debugging.</t>

      <t>Measurement Agent (MA): The function that receives Instruction
      Messages from a Controller and operates the Instruction by executing
      Measurement Tasks (using protocols outside the initial LMAP work scope
      and perhaps in concert with one or more other Measurement Agents or
      Measurement Peers) and (if part of the Instruction) by reporting
      Measurement Results to a Collector or Collectors.</t>

      <t>Measurement Agent Identifier (MA-ID): a UUID <xref target="RFC4122"/>
      that identifies a particular MA and is configured as part of the
      Bootstrapping process.</t>

      <t>Measurement Method: The process for assessing the value of a Metric;
      the process of measuring some performance or reliability parameter
      associated with the transfer of traffic; where this process involves
      multiple MAs or MPs, each may perform different roles.</t>

      <t>Measurement Peer (MP): The function that assists a Measurement Agent
      with Measurement Tasks and does not have an interface to the Controller
      or Collector.</t>

      <t>Measurement Result: The output of a single Measurement Task (the
      value obtained for the parameter of interest or Metric).</t>

      <t>Measurement Schedule: The schedule for performing Measurement
      Tasks.</t>

      <t>Measurement Task: The action performed by a particular Measurement
      Agent that consists of the single assessment of a Metric through
      operation of a Measurement Method role at a particular time, with all of
      the role's Input Parameters set to specific values.</t>

      <t>Measurement Traffic: the packet(s) generated by some types of
      Measurement Method that involve measuring some parameter associated with
      the transfer of the packet(s).</t>

      <t>Metric: The quantity related to the performance and reliability of
      the network that we'd like to know the value of, and that is carefully
      specified.</t>

      <t>Report: The set of Measurement Results and other associated
      information (as defined by the Instruction). The Report is sent by a
      Measurement Agent to a Collector.</t>

      <t>Report Channel: a communications channel between a MA and a
      Collector, which is defined by a specific MA, Collector, Report Schedule
      and associated security, and over which Reports are sent.</t>

      <t>Report Protocol: The protocol delivering Report(s) from a Measurement
      Agent to a Collector.</t>

      <t>Report Schedule: the schedule for sending Reports to a Collector.</t>

      <t>Subscriber: An entity (associated with one or more users) that is
      engaged in a subscription with a service provider.</t>

      <t>Suppression: the temporary cessation of Measurement Tasks.</t>
    </section>

    <section title="Constraints">
      <t>The LMAP framework makes some important assumptions, which constrain
      the scope of the initial LMAP work.</t>

      <section title="Measurement system is under the direction of a single organisation">
        <t>In the LMAP framework, the measurement system is under the
        direction of a single organisation that is responsible for any impact
        that its measurements have on a user's quality of experience and
        privacy. Clear responsibility is critical given that a misbehaving
        large-scale measurement system could potentially harm user experience,
        user privacy and network security.</t>

        <t>However, the components of an LMAP measurement system can be
        deployed in administrative domains that are not owned by the measuring
        organisation. Thus, the system of functions deployed by a single
        organisation constitutes a single LMAP domain which may span ownership
        or other administrative boundaries.</t>
      </section>

      <section title="Each MA may only have a single Controller at any point in time">
        <t>A MA is instructed by one Controller and is in one measurement
        system. The constraint avoids different Controllers giving a MA
        conflicting instructions and so means that the MA does not have to
        manage contention between multiple Measurement (or Report) Schedules.
        This simplifies the design of MAs (critical for a large-scale
        infrastructure) and allows a Measurement Schedule to be tested on
        specific types of MA before deployment to ensure that the end user
        experience is not impacted (due to CPU, memory or broadband-product
        constraints).</t>

        <t>An operator may have several Controllers, perhaps with a Controller
        for different types of MA (home gateways, tablets) or location
        (Ipswich, Edinburgh).</t>
      </section>
    </section>

    <section title="LMAP Protocol Model">
      <t>A protocol model <xref target="RFC4101"/> presents an architectural
      model for how the protocol operates and needs to answer three basic
      questions:</t>

      <t><list style="numbers">
          <t>What problem is the protocol trying to achieve?</t>

          <t>What messages are being transmitted and what do they mean?</t>

          <t>What are the important, but unobvious, features of the
          protocol?</t>
        </list></t>

      <t>An LMAP system goes through the following phases:</t>

      <t><list style="symbols">
          <t>a bootstrapping process before the MA can take part in the other
          three phases</t>

          <t>a Control Protocol, which delivers Instruction Messages from a
          Controller to a MA, detailing what Measurement Tasks the MA should
          perform and when, and how it should report the Measurement Results.
          It also delivers Capabilities, Failure and logging Information from
          a MA to its Controller. Finally, it allows the Controller to update
          the MA's configuration.</t>

          <t>the actual Measurement Tasks, which measure some performance or
          reliability parameter(s) associated with the transfer of packets.
          The LMAP work does not define Metrics and Measurement Methods, these
          are define elsewhere (e.g. IPPM).</t>

          <t>a Report Protocol, which delivers Reports from a MA to a
          Collector. The Report contains the Measurement Results.</t>
        </list></t>

      <t>The diagrams show the various LMAP messages and uses the following
      convention:</t>

      <t><list style="symbols">
          <t>(optional): indicated by round brackets</t>

          <t>[potentially repeated]: indicated by square brackets</t>
        </list></t>

      <t>The protocol model is closely related to the Information Model <xref
      target="I-D.ietf-lmap-information-model"/>, which is the abstract
      definition of the information carried by the protocol model. The purpose
      of both is to provide a protocol and device independent view, which can
      be implemented via specific protocols. LMAP defines a specific Control
      Protocol and Report Protocol, but others could be defined by other
      standards bodies or be proprietary. However it is important that they
      all implement the same Information Model and protocol model, in order to
      ease the definition, operation and interoperability of large-scale
      measurement systems.</t>

      <t/>

      <section title="Bootstrapping process">
        <t>The primary purpose of bootstrapping is to enable a MA to be
        integrated into a measurement system. The MA retrieves information
        about itself (like its identity in the measurement system) and about
        the Controller, the Controller learns information about the MA, and
        they learn about security information to communicate (such as
        certificates and credentials).</t>

        <t>Whilst this memo considers the bootstrapping process, it is beyond
        the scope of initial LMAP work to define a bootstrap mechanism, as it
        depends on the type of device and access.</t>

        <t>As a result of the bootstrapping process the MA learns information
        with the following aims (<xref
        target="I-D.ietf-lmap-information-model"/> defines the consequent list
        of information elements):</t>

        <t><list style="symbols">
            <t>its identifier, either its MA-ID or a device identifier such as
            its MAC or both.</t>

            <t>(optionally) a Group-ID. A Group-ID would be shared by several
            MAs and could be useful for privacy reasons. For instance,
            reporting the Group-ID and not the MA-ID could hinder tracking of
            a mobile device</t>

            <t>the Control Channel, which is defined by:<list style="symbols">
                <t>the address which identifies the Control Channel, such as
                the Controller's FQDN (Fully Qualified Domain Name) <xref
                target="RFC1035"/>)</t>

                <t>security information (for example to enable the MA to
                decrypt the Instruction Message and encrypt messages sent to
                the Controller)</t>
              </list></t>
          </list>The details of the bootstrapping process are device /access
        specific. For example, the information could be in the firmware,
        manually configured or transferred via a protocol like TR-069 <xref
        target="TR-069"/>. There may be a multi-stage process where the MA
        contacts the device at a 'hard-coded' address, which replies with the
        bootstrapping information.</t>

        <t>The MA must learn its MA-ID before getting an Instruction, either
        during Bootstrapping or via configuration (Section 5.2.1).</t>

        <t/>
      </section>

      <section title="Control Protocol">
        <t>The primary purpose of the Control Protocol is to allow the
        Controller to configure a Measurement Agent with an Instruction about
        what Measurement Tasks to do, when to do them, and how to report the
        Measurement Results (Section 5.2.2). The Measurement Agent then acts
        on the Instruction autonomously. The Control Protocol also enables the
        MA to inform the Controller about its Capabilities and any Failure and
        logging Information (Section 5.2.2). Finally, the Control Protocol
        allows the Controller to update the MA's configuration.</t>

        <t/>

        <section title="Configuration">
          <t>Configuration allows the Controller to update the MA about some
          or all of the information that it obtained during the bootstrapping
          process: the MA-ID, the (optional) Group-ID and the Control Channel.
          The measurement system might use Configuration for several reasons.
          For example, the bootstrapping process could &lsquo;hard code&rsquo;
          the MA with details of an initial Controller, and then the initial
          Controller could configure the MA with details about the Controller
          that sends Instruction Messages. (Note that a MA only has one
          Control Channel, and so is associated with only one Controller, at
          any moment.)</t>

          <t>Note that an implementation may choose to combine Configuration
          information and an Instruction Message into a single message.</t>

          <t><figure>
              <artwork><![CDATA[+-----------------+                                      +-------------+
|                 |                                      | Measurement |
|  Controller     |======================================|  Agent      |
+-----------------+                                      +-------------+

Configuration information:               ->
(MA-ID),
(Group-ID),
(Control Channel) 
                                         <-          Response(details)
   
 
]]></artwork>
            </figure></t>
        </section>

        <section title="Instruction">
          <t>The Instruction is the description of the Measurement Tasks for a
          Measurement Agent to do and the details of the Measurement Reports
          for it to send. In order to update the Instruction the Controller
          uses the Control Protocol to send an Instruction Message over the
          Control Channel.</t>

          <t/>

          <t><figure>
              <artwork><![CDATA[+-----------------+                                      +-------------+
|                 |                                      | Measurement |
|  Controller     |======================================|  Agent      |
+-----------------+                                      +-------------+ 

Instruction:                            ->
[(Measurement Task configuration(
   [Input Parameter], 
   (interface),
   (Cycle-ID))),
 (Report Channel),
 (Measurement Schedule),
 (Report Schedule),
 (Suppression information)]
                                         <-          Response(details)    
 
]]></artwork>
            </figure></t>

          <t>The Instruction defines information with the following aims
          (<xref target="I-D.ietf-lmap-information-model"/> defines the
          consequent list of information elements):</t>

          <t><list style="symbols">
              <t>the Measurement Task configurations, each of which
              needs:<list style="symbols">
                  <t>the Metric, specified as a URI to a registry entry; it
                  includes the specification of a Measurement Method. The
                  registry could be defined by the IETF <xref
                  target="I-D.manyfolks-ippm-metric-registry"/>, locally by
                  the operator of the measurement system or perhaps by another
                  standards organisation.</t>

                  <t>the Measurement Method role. For some Measurement
                  Methods, different parties play different roles; for example
                  (figure A3 in the Appendix) an iperf sender and receiver.
                  Each Metric and its associated Measurement Method will
                  describe all measurement roles involved in the process.
                  Thus, the Measurement Method role is an Input Parameter.</t>

                  <t>a boolean flag (suppress or do-not-suppress) indicating
                  how such a Measurement Task is impacted by a Suppression
                  message (see Section 5.2.2.1). Thus, the flag is an Input
                  Parameter.</t>

                  <t>any Input Parameters that need to be set for the Metric
                  and the Measurement Method, such as the address of a
                  Measurement Peer (or other Measurement Agent) that may be
                  involved in a Measurement Task, and for the measurement
                  protocol used, such as protocol role(s).</t>

                  <t>if the device with the MA has multiple interfaces, then
                  the interface to use (if not defined, then the default
                  interface is used)</t>
                </list></t>

              <t>configuration of the Measurement Schedules, each of which
              needs:<list style="symbols">
                  <t>the timing of when the Measurement Tasks are to be
                  performed. Possible types of timing are periodic,
                  calendar-based periodic, one-off immediate and one-off at a
                  future time</t>
                </list></t>

              <t>configuration of the Report Channels, each of which
              needs:<list style="symbols">
                  <t>the address of the Collector, for instance its URL</t>

                  <t>security for this Report Channel, for example the X.509
                  certificate</t>
                </list></t>

              <t>configuration of the Report Schedules, each of which
              needs:<list style="symbols">
                  <t>the timing of when reporting is to be performed. For
                  instance, every hour or immediately.</t>
                </list></t>

              <t>Suppression information, if any (see Section 5.2.1.1)</t>
            </list></t>

          <t>A single Instruction Message may contain some or all of the above
          parts. The finest level of granularity possible in an Instruction
          Message is determined by the implementation and operation of the
          Control Protocol. For example, a single Instruction Message may add
          or update an individual Measurement Schedule - or it may only update
          the complete set of Measurement Schedules; a single Instruction
          Message may update both Measurement Schedules and Measurement Task
          configurations - or only one at a time; and so on.</t>

          <t>The MA informs the Controller that it has successfully understood
          the Instruction Message, or that it cannot action the Instruction -
          for example, if it doesn't include a parameter that is mandatory for
          the requested Metric and Measurement Method, or it is missing
          details of the target Collector.</t>

          <t>The Instruction Message instructs the MA; the Control Protocol
          does not allow the MA to negotiate, as this would add complexity to
          the MA, Controller and Control Protocol for little benefit.</t>

          <t/>

          <section title="Suppression">
            <t>The Instruction may include Suppression information. The
            purpose of Suppression is to enable the Controller to instruct the
            MA not to perform Measurement Tasks. It is used if the measurement
            system wants to eliminate inessential traffic, because there is
            some unexpected network issue for example.</t>

            <t>The Suppression information may include any of the following
            optional fields:</t>

            <t><list style="symbols">
                <t>a set of Measurement Tasks to suppress; the others are not
                suppressed. For example, this could be useful if a particular
                Measurement Task is overloading a Measurement Peer.</t>

                <t>a set of Measurement Schedules to suppress; the others are
                not suppressed. For example, suppose the measurement system
                has defined two Schedules, one with the most critical
                Measurement Tasks and the other with less critical ones that
                create a lot of Measurement Traffic, then it may only want to
                suppress the second.</t>

                <t>if the Suppression information includes neither a set of
                Measurement Tasks nor a set of Measurement Schedules, then the
                MA does not begin new Measurement Tasks that have the boolean
                flag set to "suppress"; however, the MA does begin new
                Measurement Tasks that have the flag set to
                "do-not-suppress".</t>

                <t>a start time, at which suppression begins. If absent, then
                Suppression begins immediately.</t>

                <t>an end time, at which suppression ends. If absent, then
                Suppression continues until the MA receives an un-Suppress
                message.</t>

                <t>a demand that the MA immediately ends on-going Measurement
                Task(s) that are tagged for suppression (and deletes the
                associated partial Measurement Result(s)). This could be
                useful in the case of a network emergency so that the operator
                can eliminate all inessential traffic as rapidly as possible.
                If absent, the MA completes on-going Measurement Tasks.</t>
              </list></t>

            <t>So the default action (if none of the optional fields is set)
            is that the MA does not begin any new Measurement Task with the
            "suppress" flag.</t>

            <t>An un-Suppress message instructs the MA no longer to suppress,
            meaning that the MA once again begins new Measurement Tasks,
            according to its Measurement Schedule.</t>

            <t>Note that Suppression is not intended to permanently stop a
            Measurement Task (instead, the Controller should send a new
            Measurement Schedule), nor to permanently disable a MA (instead,
            some kind of management action is suggested).</t>

            <figure>
              <artwork><![CDATA[+-----------------+                                   +-------------+
|                 |                                   | Measurement |
|  Controller     |===================================|  Agent      |
+-----------------+                                   +-------------+ 

Suppress:
[(Measurement Task),                     ->               
 (Measurement Schedule),
 [start time], 
 [end time],
 [on-going suppressed?]]
 
Un-suppress                              ->
                                       
]]></artwork>
            </figure>
          </section>
        </section>

        <section title="Capabilities and Failure information">
          <t>The Control Protocol also enables the MA to inform the Controller
          about various information, such as its Capabilities and any
          Failures. It is also possible to use a device-specific mechanism
          which is beyond the scope of the initial LMAP work.</t>

          <t>Capabilities are information about the MA that the Controller
          needs to know in order to correctly instruct the MA, such as:</t>

          <t><list style="symbols">
              <t>the Measurement Method (roles) that the MA supports</t>

              <t>the measurement protocol types and roles that the MA
              supports</t>

              <t>the interfaces that the MA has</t>

              <t>the version of the MA</t>

              <t>the version of the hardware, firmware or software of the
              device with the MA</t>

              <t>but not dynamic information like the currently unused CPU,
              memory or battery life of the device with the MA.</t>
            </list></t>

          <t>Failure information concerns why the MA has been unable to
          execute a Measurement Task or deliver a Report, for example:</t>

          <t><list style="symbols">
              <t>the Measurement Task failed to run properly because the MA
              (unexpectedly) has no spare CPU cycles</t>

              <t>the MA failed record the Measurement Results because it
              (unexpectedly) is out of spare memory</t>

              <t>a Report failed to deliver Measurement Results because the
              Collector (unexpectedly) is not responding</t>

              <t>but not if a Measurement Task correctly doesn't start. For
              example, the first step of some Measurement Methods is for the
              MA to check there is no cross-traffic.</t>
            </list></t>

          <t>Logging information concerns how the MA is operating and may help
          debugging, for example:</t>

          <t><list style="symbols">
              <t>the last time the MA ran a Measurement Task</t>

              <t>the last time the MA sent a Measurement Report</t>

              <t>the last time the MA received an Instruction Message</t>

              <t>whether the MA is currently Suppressing Measurement Tasks</t>
            </list></t>

          <t>Capabilities, failure and logging information are sent by the MA,
          either in response to a request from the Controller (for example, if
          the Controller forgets what the MA can do or otherwise wants to
          resynchronize what it knows about the MA), or on its own initiative
          (for example when the MA first communicates with a Controller or if
          it becomes capable of a new Measurement Method). Another example of
          the latter case is if the device with the MA re-boots, then the MA
          should notify its Controller in case its Instruction needs to be
          updated; to avoid a "mass calling event" after a widespread power
          restoration affecting many MAs, it is sensible for an MA to pause
          for a random delay, perhaps in the range of one minute or so.</t>

          <t><figure>
              <artwork><![CDATA[+-----------------+                                   +-------------+
|                 |                                   | Measurement |
|  Controller     |===================================|  Agent      |
+-----------------+                                   +-------------+ 

(Instruction: 
  [(Request Capabilities),
    (Request Failure Information),
    (Request Logging Information)])       ->
                                         <-         (Capabilities),
                                                    (Failure Information),
                                                    (Logging Information)
 
]]></artwork>
            </figure></t>

          <t/>
        </section>
      </section>

      <section title="Operation of Measurement Tasks">
        <t>This LMAP framework is neutral to what the actual Measurement Task
        is. It does not define Metrics and Measurement Methods, these are
        defined elsewhere (e.g. IPPM).</t>

        <t>The MA carries out the Measurement Tasks as instructed, unless it
        gets an updated Instruction. The MA acts autonomously, in terms of
        operation of the Measurement Tasks and reporting of the Results; it
        doesn't do a 'safety check' with the Controller to ask whether it
        should still continue with the requested Measurement Tasks.</t>

        <t/>

        <section title="Starting and Stopping Measurement Tasks">
          <t>This LMAP framework does not define a generic start and stop
          process, since the correct approach depends on the particular
          Measurement Task; the details are defined as part of each
          Measurement Method. This section provides some general hints. The MA
          does not inform the Controller about Measurement Tasks starting and
          stopping.</t>

          <t>Before sending Measurement Traffic the MA may run a pre-check.
          (The pre-check could be defined as a separate, preceding Task or as
          the first part of a larger Task.) Action could include:</t>

          <t><list style="symbols">
              <t>the MA checking that there is no cross-traffic. In other
              words, a check that the end-user isn't already sending
              traffic;</t>

              <t>the MA checking with the Measurement Peer (or other
              Measurement Agent involved in the Measurement Task) that it can
              handle a new Measurement Task (in case, for example, the
              Measurement Peer is already handling many Measurement Tasks with
              other MAs);</t>

              <t>sending traffic that probes the path to check it isn't
              overloaded;</t>

              <t>checking that the device with the MA has enough resources to
              execute the Measurement Task reliably. Note that the designer of
              the measurement system should ensure that the device's
              capabilities are normally sufficient to comfortably operate the
              Measurement Tasks.</t>
            </list>It is possible that similar checks continue during the
          Measurement Task, especially one that is long-running and/or creates
          a lot of Measurement Traffic, and might lead to it being abandoned
          whilst in-progress. A Measurement Task could also be abandoned in
          response to a "suppress" message (see Section 5.2.1). Action could
          include:</t>

          <t><list style="symbols">
              <t>For &lsquo;upload&rsquo; tests, the MA not sending
              traffic</t>

              <t>For &lsquo;download&rsquo; tests, the MA closing the TCP
              connection or sending a TWAMP Stop control message <xref
              target="RFC5357"/>.</t>
            </list></t>

          <t>The Controller may want a MA to run the same Measurement Task
          indefinitely (for example, "run the 'upload speed' Measurement Task
          once an hour until further notice"). To avoid the MA generating
          traffic forever after a Controller has permanently failed (or
          communications with the Controller have failed), the MA can be
          configured with a time limit; if the MA doesn't hear from the
          Controller for this length of time, then it stops operating
          Measurement Tasks.</t>

          <t/>
        </section>

        <section title="Overlapping Measurement Tasks">
          <t>It is possible that a MA starts a new Measurement Task before
          another Measurement Task has completed. This may be intentional (the
          way that the measurement system has designed the Measurement
          Schedules), but it could also be unintentional - for instance, if a
          Measurement Task has a 'wait for X' step which pauses for an
          unexpectedly long time. The operator of the measurement system can
          handle (or not) overlapping Measurement Tasks in any way they choose
          - it is a policy or implementation issue and not the concern of
          LMAP. Some possible approaches are: to configure the MA not to begin
          the second Measurement Task; to start the second Measurement Task as
          usual; for the action to be an Input Parameter of the Measurement
          Task; and so on.</t>

          <t>It may be important to include in the Measurement Report the fact
          that the Measurement Task overlapped with another.</t>
        </section>
      </section>

      <section title="Report Protocol">
        <t>The primary purpose of the Report Protocol is to allow a
        Measurement Agent to report its Measurement Results to a Collector,
        along with the context in which they were obtained.</t>

        <t><figure>
            <artwork><![CDATA[+-----------------+                                   +-------------+
|                 |                                   | Measurement |
|   Collector     |===================================|  Agent      |
+-----------------+                                   +-------------+ 
                                                       
                                   <-    Report: 
                                                 [MA-ID &/or Group-ID],
                                                  [Measurement Result],
                                          [details of Measurement Task]
ACK                                ->

]]></artwork>
          </figure></t>

        <t>The Report contains:<list style="symbols">
            <t>the MA-ID or a Group-ID (to anonymise results)</t>

            <t>the actual Measurement Results, including the time they were
            measured</t>

            <t>the details of the Measurement Task (to avoid the Collector
            having to ask the Controller for this information later)</t>

            <t>perhaps the Subscriber's service parameters (see Section
            5.4.1).</t>
          </list></t>

        <t>The MA sends Reports as defined by the Instruction. It is possible
        that the Instruction tells the MA to report the same Results to more
        than one Collector, or to report a different subset of Results to
        different Collectors. It is also possible that a Measurement Task may
        create two (or more) Measurement Results, which could be reported
        differently (for example, one Result could be reported periodically,
        whilst the second Result could be an alarm that is created as soon as
        the measured value of the Metric crosses a threshold and that is
        reported immediately).</t>

        <t>Optionally, a Report is not sent when there are no Measurement
        Results.</t>

        <t>In the initial LMAP Information Model and Report Protocol, for
        simplicity we assume that all Measurement Results are reported as-is,
        but allow extensibility so that a measurement system (or perhaps a
        second phase of LMAP) could allow a MA to:</t>

        <t><list style="symbols">
            <t>label, or perhaps not include, Measurement Results impacted by,
            for instance, cross-traffic or the Measurement Peer (or other
            Measurement Agent) being busy</t>

            <t>label Measurement Results obtained by a Measurement Task that
            overlapped with another</t>

            <t>not report the Measurement Results if the MA believes that they
            are invalid</t>

            <t>detail when Suppression started and ended</t>
          </list></t>

        <t/>

        <section title="Reporting of Subscriber's service parameters">
          <t>The Subscriber's service parameters are information about his/her
          broadband contract, line rate and so on. Such information is likely
          to be needed to help analyse the Measurement Results, for example to
          help decide whether the measured download speed is reasonable.</t>

          <t>The information could be transferred directly from the Subscriber
          parameter database to the data analysis tools. It may also be
          possible to transfer the information via the MA. How (and if) the MA
          knows such information is likely to depend on the device type. The
          MA could either include the information in a Measurement Report or
          separately.</t>
        </section>
      </section>

      <section title="Operation of LMAP over the underlying packet transfer mechanism">
        <t>The above sections have described LMAP's protocol model. Other
        specifications will define the actual Control and Report Protocols,
        possibly operating over an existing protocol, such as REST-style
        HTTP(S). It is also possible that a different choice is made for the
        Control and Report Protocols, for example NETCONF-YANG and IPFIX
        respectively.</t>

        <t>From an LMAP perspective, the Controller needs to know that the MA
        has received the Instruction Message, or at least that it needs to be
        re-sent as it may have failed to be delivered. Similarly the MA needs
        to know about the delivery of Capabilities and Failure information to
        the Controller and Reports to the Collector. How this is done depends
        on the design of the Control and Report Protocols and the underlying
        packet transfer mechanism.</t>

        <t>For the Control Protocol, the underlying packet transfer mechanism
        could be:</t>

        <t><list style="symbols">
            <t>a 'push' protocol (that is, from the Controller to the MA)</t>

            <t>a multicast protocol (from the Controller to a group of
            MAs)</t>

            <t>a 'pull' protocol. The MA periodically checks with Controller
            if the Instruction has changed and pulls a new Instruction if
            necessary. A pull protocol seems attractive for a MA behind a NAT
            (as is typical for a MA on an end-user's device), so that it can
            initiate the communications. A pull mechanism is likely to require
            the MA to be configured with how frequently it should check in
            with the Controller, and perhaps what it should do if the
            Controller is unreachable after a certain number of attempts.</t>

            <t>a hybrid protocol. In addition to a pull protocol, the
            Controller can also push an alert to the MA that it should
            immediately pull a new Instruction.</t>
          </list>For the Report Protocol, the underlying packet transfer
        mechanism could be:</t>

        <t><list style="symbols">
            <t>a 'push' protocol (that is, from the MA to the Collector)</t>

            <t>perhaps supplemented by the ability for the Collector to 'pull'
            Measurement Results from a MA.</t>
          </list></t>
      </section>

      <section title="Items beyond the scope of the initial LMAP work">
        <t>There are several potential interactions between LMAP elements that
        are beyond the scope of the initial LMAP work:</t>

        <t><list style="numbers">
            <t>It does not define a coordination process between MAs. Whilst a
            measurement system may define coordinated Measurement Schedules
            across its various MAs, there is no direct coordination between
            MAs.</t>

            <t>It does not define interactions between the Collector and
            Controller. It is quite likely that there will be such
            interactions, optionally intermediated by the data analysis tools.
            For example, if there is an "interesting" Measurement Result then
            the measurement system may want to trigger extra Measurement Tasks
            that explore the potential cause in more detail; or if the
            Collector unexpectedly does not hear from a MA, then the
            measurement system may want to trigger the Controller to send a
            fresh Instruction Message to the MA.</t>

            <t>It does not define coordination between different measurement
            systems. For example, it does not define the interaction of a MA
            in one measurement system with a Controller or Collector in a
            different measurement system. Whilst it is likely that the Control
            and Report Protocols could be re-used or adapted for this
            scenario, any form of coordination between different organisations
            involves difficult commercial and technical issues and so, given
            the novelty of large-scale measurement efforts, any form of
            inter-organisation coordination is outside the scope of the
            initial LMAP work. Note that a single MA is instructed by a single
            Controller and is only in one measurement system.<list
                style="symbols">
                <t>An interesting scenario is where a home contains two
                independent MAs, for example one controlled by a regulator and
                one controlled by an ISP. Then the Measurement Traffic of one
                MA is treated by the other MA just like any other end-user
                traffic.</t>
              </list></t>

            <t>It does not consider how to prevent a malicious party "gaming
            the system". For example, where a regulator is running a
            measurement system in order to benchmark operators, a malicious
            operator could try to identify the broadband lines that the
            regulator was measuring and prioritise that traffic. It is assumed
            this is a policy issue and would be dealt with through a code of
            conduct for instance.</t>

            <t>It does not define how to analyse Measurement Results,
            including how to interpret missing Results.</t>

            <t>It does not specifically define a end-user-controlled
            measurement system, see sub-section 5.6.1.</t>
          </list></t>

        <section title="End-user-controlled measurement system">
          <t>This framework concentrates on the cases where an ISP or a
          regulator runs the measurement system. However, we expect that LMAP
          functionality will also be used in the context of an
          end-user-controlled measurement system. There are at least two ways
          this could happen (they have various pros and cons):</t>

          <t><list style="numbers">
              <t>an end-user could somehow request the ISP- (or regulator-)
              run measurement system to test his/her line. The ISP (or
              regulator) Controller would then send an Instruction to the MA
              in the usual LMAP way.</t>

              <t>an end-user could deploy their own measurement system, with
              their own MA, Controller and Collector. For example, the user
              could implement all three functions onto the same end-user-owned
              end device, perhaps by downloading the functions from the ISP or
              regulator. Then the LMAP Control and Report Protocols do not
              need to be used, but using LMAP's Information Model would still
              be beneficial. The Measurement Peer (or other MA involved in the
              Measurement Task) could be in the home gateway or outside the
              home network; in the latter case the Measurement Peer is highly
              likely to be run by a different organisation, which raises extra
              privacy considerations.</t>
            </list></t>

          <t>In both cases there will be some way for the end-user to initiate
          the Measurement Task(s). The mechanism is outside the scope of the
          initial LMAP work, but could include the user clicking a button on a
          GUI or sending a text message. Presumably the user will also be able
          to see the Measurement Results, perhaps summarised on a webpage. It
          is suggested that these interfaces conform to the LMAP guidance on
          privacy in Section 8.</t>

          <t/>
        </section>
      </section>
    </section>

    <section title="Deployment considerations">
      <t>The Appendix has some examples of possible deployment arrangements of
      Measurement Agents and Peers.</t>

      <section title="Controller and the measurement system">
        <t>The Controller should understand both the MA's LMAP Capabilities
        (for instance what Metrics and Measurement Methods it can perform) and
        about the MA's other capabilities like processing power and memory.
        This allows the Controller to make sure that the Measurement Schedule
        of Measurement Tasks and the Reporting Schedule are sensible for each
        MA that it instructs.</t>

        <t>An Instruction is likely to include several Measurement Tasks.
        Typically these run at different times, but it is also possible for
        them to run at the same time. Some Tasks may be compatible, in that
        they do not affect each other's Results, whilst with others great care
        would need to be taken.</t>

        <t>The Controller should ensure that the Measurement Tasks do not have
        an adverse effect on the end user. Tasks, especially those that
        generate a substantial amount of traffic, will often include a
        pre-check that the user isn't already sending traffic (Section 5.3).
        Another consideration is whether Measurement Traffic will impact a
        Subscriber's bill or traffic cap.</t>

        <t>The different elements of the Instruction can be updated
        independently. For example, the Measurement Tasks could be configured
        with different Input Parameters whilst keeping the same Measurement
        Schedule. In general this should not create any issues, since Metrics
        and their associated Measurement Methods should be defined so their
        fundamental nature does not change for a new value of Input Parameter.
        There could be a problem if, for example, a Measurement Task involving
        a 1kB file upload could be changed into a 1GB file upload.</t>

        <t>A measurement system may have multiple Controllers (but note the
        overriding principle that a single MA is instructed by a single
        Controller at any point in time (Section 4.2)). For example, there
        could be different Controllers for different types of MA (home
        gateways, tablets) or locations (Ipswich, Edinburgh), for load
        balancing or to cope with failure of one Controller.</t>

        <t>The measurement system also needs to consider carefully how to
        interpret missing Results; for example, if the missing Results are
        ignored and the lack of a Report is caused by its broadband being
        broken, then the estimate of overall performance, averaged across all
        MAs, would be too optimistic.</t>
      </section>

      <section title="Measurement Agent">
        <t>The Measurement Agent could take a number of forms: a dedicated
        probe, software on a PC, embedded into an appliance, or even embedded
        into a gateway. A single site (home, branch office etc.) that is
        participating in a measurement could make use of one or multiple
        Measurement Agents or Measurement Peers in a single measurement.</t>

        <t>The Measurement Agent could be deployed in a variety of locations.
        Not all deployment locations are available to every kind of
        Measurement Agent. There are also a variety of limitations and
        trade-offs depending on the final placement. The next sections outline
        some of the locations a Measurement Agent may be deployed. This is not
        an exhaustive list and combinations may also apply.</t>

        <t/>

        <section title="Measurement Agent on a networked device">
          <t>A MA may be embedded on a device that is directly connected to
          the network, such as a MA on a smartphone. Other examples include a
          MA downloaded and installed on a subscriber's laptop computer or
          tablet when the network service is provided on wired or other
          wireless radio technologies, such as Wi-Fi.</t>
        </section>

        <section title="Measurement Agent embedded in site gateway">
          <t>A Measurement Agent embedded with the site gateway, for example a
          home router or the edge router of a branch office in a managed
          service environment, is one of better places the Measurement Agent
          could be deployed. All site-to-ISP traffic would traverse through
          the gateway. So, Measurement Methods that measure user traffic could
          easily be performed. Similarly, due to this user traffic visibility,
          a Measurement Method that generates Measurement Traffic could ensure
          it does not compete with user traffic. Generally NAT and firewall
          services are built into the gateway, allowing the Measurement Agent
          the option to offer its Controller-facing management interface
          outside of the NAT/firewall. This placement of the management
          interface allows the Controller to unilaterally contact the
          Measurement Agent for instructions. However, a Measurement Agent on
          a site gateway (whether end-user service-provider owned) will
          generally not be directly available for over the top providers, the
          regulator, end users or enterprises.</t>

          <t/>
        </section>

        <section title="Measurement Agent embedded behind site NAT /Firewall">
          <t>The Measurement Agent could also be embedded behind a NAT, a
          firewall, or both. In this case the Controller may not be able to
          unilaterally contact the Measurement Agent unless either static port
          forwarding or firewall pin holing is configured. Configuring port
          forwarding could use protocols such as PCP <xref target="RFC6887"/>,
          TR-069 <xref target="TR-069"/> or UPnP <xref target="UPnP"/>. To
          prop open the firewall, the Measurement Agent could send keepalives
          towards the Controller (and perhaps use these also as a network
          reachability test).</t>
        </section>

        <section title="Multi-homed Measurement Agent">
          <t>If the device with the Measurement Agent is single homed then
          there is no confusion about what interface to measure. Similarly, if
          the MA is at the gateway and the gateway only has a single WAN-side
          and a single LAN-side interface, there is little confusion - for
          Measurement Methods that generate Measurement Traffic, the location
          of the other MA or Measurement Peer determines whether the WAN or
          LAN is measured.</t>

          <t>However, the device with the Measurement Agent may be
          multi-homed. For example, a home or campus may be connected to
          multiple broadband ISPs, such as a wired and wireless broadband
          provider, perhaps for redundancy or load- sharing. It may also be
          helpful to think of dual stack IPv4 and IPv6 broadband devices as
          multi-homed. More generally, Section 3.2 of <xref
          target="I-D.ietf-homenet-arch"/> describes dual-stack and
          multi-homing topologies that might be encountered in a home network,
          <xref target="RFC6419"/> provides the current practices of
          multi-interfaces hosts, and the Multiple Interfaces (mif) working
          group covers cases where hosts are either directly attached to
          multiple networks (physical or virtual) or indirectly (multiple
          default routers, etc.). In these cases, there needs to be clarity on
          which network connectivity option is being measured.</t>

          <t>One possibility is to have a Measurement Agent per interface.
          Then the Controller's choice of MA determines which interface is
          measured. However, if a MA can measure any of the interfaces, then
          the Controller defines in the Instruction which interface the MA
          should use for a Measurement Task; if the choice of interface is not
          defined then the MA uses the default one. Explicit definition is
          preferred if the measurement system wants to measure the performance
          of a particular network, whereas using the default is better if the
          measurement system wants to include the impact of the MA's interface
          selection algorithm. In any case, the Measurement Result should
          include the network that was measured.</t>

          <t/>
        </section>

        <section title="Measurement Agent embedded in ISP Network">
          <t>A MA may be embedded on a device that is part of an ISP's
          network, such as a router or switch. Usually the network devices
          with an embedded MA will be strategically located, such as a Carrier
          Grade NAT or ISP Gateway. <xref target="I-D.ietf-ippm-lmap-path"/>
          gives many examples where a MA might be located within a network to
          provide an intermediate measurement point on the end-to-end path.
          Other examples include a network device whose primary role is to
          host MA functions and the necessary measurement protocol.</t>
        </section>
      </section>

      <section title="Measurement Peer">
        <t>A Measurement Peer participates in some Measurement Methods. It may
        have specific functionality to enable it to participate in a
        particular Measurement Method. On the other hand, other Measurement
        Methods may require no special functionality, for example if the
        Measurement Agent sends a ping to example.com then the server at
        example.com plays the role of a Measurement Peer.</t>

        <t>A device may participate in some Measurement Methods as a
        Measurement Agent and in others as a Measurement Peer.</t>

        <t>Measurement Schedules should account for limited resources in a
        Measurement Peer when instructing a MA to execute measurements with a
        Measurement Peer. In some measurement protocols, such as <xref
        target="RFC4656"/> and <xref target="RFC5357"/>, the Measurement Peer
        can reject a measurement session or refuse a control connection prior
        to setting-up a measurement session and so protect itself from
        resource exhaustion. This is a valuable capability because the MP may
        be used by more than one organisation.</t>
      </section>
    </section>

    <section title="Security considerations">
      <t/>

      <t>The security of the LMAP framework should protect the interests of
      the measurement operator(s), the network user(s) and other actors who
      could be impacted by a compromised measurement deployment. The
      measurement system must secure the various components of the system from
      unauthorised access or corruption. Much of the general advice contained
      in section 6 of <xref target="RFC4656"/> is applicable here.</t>

      <t>The process to upgrade the firmware in an MA is outside the scope of
      the initial LMAP work, similar to the protocol to bootstrap the MAs (as
      specified in the charter). However, systems which provide remote upgrade
      must secure authorised access and integrity of the process.</t>

      <t>We assume that each Measurement Agent (MA) will receive its
      Instructions from a single organisation, which operates the Controller.
      These Instructions must be authenticated (to ensure that they come from
      the trusted Controller), checked for integrity (to ensure no-one has
      tampered with them) and not vulnerable to replay attacks. If a malicious
      party can gain control of the MA they can use it to launch DoS attacks
      at targets, reduce the end user's quality of experience and corrupt the
      Measurement Results that are reported to the Collector. By altering the
      Measurement Tasks and/or the address that Results are reported to, they
      can also compromise the confidentiality of the network user and the MA
      environment (such as information about the location of devices or their
      traffic). The Instruction messages also need to be encrypted to maintain
      confidentiality, as the information might be useful to an attacker.</t>

      <t>In some circumstances (if the MA is behind a NAT for instance), the
      Controller cannot contact the MA directly an so the MA must contact the
      Controller (the "pull" model). The Controller should ensure that its
      resources cannot be exhausted by a malicious party pretending to be a
      MA. For example, the Controller could limit the rate of "pull" requests
      from a single MA.</t>

      <t>Reporting by the MA must be encrypted to maintain confidentiality, so
      that only the authorised Collector can decrypt the results, to prevent
      the leakage of confidential or private information. Reporting must also
      be authenticated (to ensure that it comes from a trusted MA) and not
      vulnerable to tampering (which can be ensured through integrity and
      replay checks). It must not be possible to fool a MA into injecting
      falsified data and the results must also be held and processed securely
      after collection and analysis. See section 8.5.2 below for additional
      considerations on stored data compromise, and section 8.6 on potential
      mitigations for compromise.</t>

      <t>Since Collectors will be contacted repeatedly by MAs using the
      Collection Protocol to convey their recent results, a successful attack
      to exhaust the communication resources would prevent a critical
      operation: reporting. Therefore, all LMAP Collectors should implement
      technical mechanisms to:</t>

      <t><list style="symbols">
          <t>limit the number of reporting connections from a single MA
          (simultaneous, and connections per unit time).</t>

          <t>limit the transmission rate from a single MA.</t>

          <t>limit the memory/storage consumed by a single MA's reports.</t>

          <t>efficiently reject reporting connections from unknown
          sources.</t>

          <t>separate resources if multiple authentication strengths are used,
          where the resources should be separated according to each class of
          strength.</t>
        </list></t>

      <t>The security mechanisms described above may not be strictly necessary
      if the network's design ensures the LMAP components and their
      communications are already secured, for example potentially if they are
      all part of an ISP's dedicated management network.</t>

      <t>Finally, there are three other issues related to security: privacy
      (considered in Section 8 below), availability and 'gaming the system'.
      While the loss of some MAs may not be considered critical, the
      unavailability of the Collector could mean that valuable business data
      or data critical to a regulatory process is lost. Similarly, the
      unavailability of a Controller could mean that the MAs do not operate a
      correct Measurement Schedule.</t>

      <t>A malicious party could "game the system". For example, where a
      regulator is running a measurement system in order to benchmark
      operators, an operator could try to identify the broadband lines that
      the regulator was measuring and prioritise that traffic. Normally, this
      potential issue is handled by a code of conduct. It is outside the scope
      of the initial LMAP work to consider the issue.</t>

      <t/>
    </section>

    <section title="Privacy Considerations for LMAP">
      <t>The LMAP work considers privacy as a core requirement and will ensure
      that by default the Control and Report Protocols operate in a
      privacy-sensitive manner and that privacy features are well-defined.</t>

      <t>This section provides a set of privacy considerations for LMAP. This
      section benefits greatly from the timely publication of <xref
      target="RFC6973"/>. Privacy and security (Section 7) are related. In
      some jurisdictions privacy is called data protection.</t>

      <t>We begin with a set of assumptions related to protecting the
      sensitive information of individuals and organisations participating in
      LMAP-orchestrated measurement and data collection.</t>

      <section title="Categories of Entities with Information of Interest">
        <t>LMAP protocols need to protect the sensitive information of the
        following entities, including individuals and organisations who
        participate in measurement and collection of results.<list
            style="symbols">
            <t>Individual Internet users: Persons who utilise Internet access
            services for communications tasks, according to the terms of
            service of a service agreement. Such persons may be a service
            Subscriber, or have been given permission by the Subscriber to use
            the service.</t>

            <t>Internet service providers: Organisations who offer Internet
            access service subscriptions, and thus have access to sensitive
            information of individuals who choose to use the service. These
            organisations desire to protect their Subscribers and their own
            sensitive information which may be stored in the process of
            performing Measurement Tasks and collecting and Results.</t>

            <t>Regulators: Public authorities responsible for exercising
            supervision of the electronic communications sector, and which may
            have access to sensitive information of individuals who
            participate in a measurement campaign. Similarly, regulators
            desire to protect the participants and their own sensitive
            information.</t>

            <t>Other LMAP system operators: Organisations who operate
            measurement systems or participate in measurements in some
            way.</t>
          </list></t>

        <t>Although privacy is a protection extended to individuals, we
        include discussion of ISPs and other LMAP system operators in this
        section. These organisations have sensitive information involved in
        the LMAP system, and many of the same dangers and mitigations are
        applicable. Further, the ISPs store information on their Subscribers
        beyond that used in the LMAP system (for instance billing
        information), and there should be a benefit in considering all the
        needs and potential solutions coherently.</t>
      </section>

      <section title="Examples of Sensitive Information">
        <t>This section gives examples of sensitive information which may be
        measured or stored in a measurement system, and which is to be kept
        private by default in the LMAP core protocols.</t>

        <t>Examples of Subscriber or authorised Internet user sensitive
        information:</t>

        <t><list style="symbols">
            <t>Sub-IP layer addresses and names (MAC address, base station ID,
            SSID)</t>

            <t>IP address in use</t>

            <t>Personal Identification (real name)</t>

            <t>Location (street address, city)</t>

            <t>Subscribed service parameters</t>

            <t>Contents of traffic (activity, DNS queries, destinations,
            equipment types, account info for other services, etc.)</t>

            <t>Status as a study volunteer and Schedule of Measurement
            Tasks</t>
          </list></t>

        <t>Examples of Internet Service Provider sensitive information:<list
            style="symbols">
            <t>Measurement device identification (equipment ID and IP
            address)</t>

            <t>Measurement Instructions (choice of measurements)</t>

            <t>Measurement Results (some may be shared, others may be
            private)</t>

            <t>Measurement Schedule (exact times)</t>

            <t>Network topology (locations, connectivity, redundancy)</t>

            <t>Subscriber billing information, and any of the above Subscriber
            information known to the provider.</t>

            <t>Authentication credentials (such as certificates)</t>
          </list></t>

        <t>Other organisations will have some combination of the lists above.
        The LMAP system would not typically expose all of the information
        above, but could expose a combination of items which could be
        correlated with other pieces collected by an attacker (as discussed in
        the section on Threats below).</t>
      </section>

      <section title="Different privacy issues raised by different sorts of Measurement Methods">
        <t>Measurement Methods raise different privacy issues depending on
        whether they measure traffic created specifically for that purpose, or
        whether they measure user traffic.</t>

        <t>Measurement Tasks conducted on user traffic store sensitive
        information, however briefly this storage may be. We note that some
        authorities make a distinction on time of storage, and information
        that is kept only temporarily to perform a communications function is
        not subject to regulation (for example, active queue management, deep
        packet inspection). Such Measurement Tasks could reveal all the
        websites a Subscriber visits and the applications and/or services they
        use.</t>

        <t>Other types of Measurement Task are conducted on traffic which is
        created specifically for the purpose. Even if a user host generates
        Measurement Traffic, there is limited sensitive information about the
        Subscriber present and stored in the measurement system:<list
            style="symbols">
            <t>IP address in use (and possibly sub-IP addresses and names)</t>

            <t>Status as a study volunteer and Schedule of Measurement
            Tasks</t>
          </list></t>

        <t>On the other hand, for a service provider the sensitive information
        like Measurement Results is the same for all Measurement Tasks.</t>

        <t>From the Subscriber perspective, both types of Measurement Task
        potentially expose the description of Internet access service and
        specific service parameters, such as subscribed rate and type of
        access.</t>
      </section>

      <section title="Privacy analysis of the Communications Models">
        <t>This section examines each of the protocol exchanges described at a
        high level in Section 5 and some example Measurement Tasks, and
        identifies specific sensitive information which must be secured during
        communication for each case. With the protocol-related sensitive
        information identified, we can better consider the threats described
        in the following section.</t>

        <t>From the privacy perspective, all entities participating in LMAP
        protocols can be considered "observers" according to the definition in
        <xref target="RFC6973"/>. Their stored information potentially poses a
        threat to privacy, especially if one or more of these functional
        entities has been compromised. Likewise, all devices on the paths used
        for control, reporting, and measurement are also observers.</t>

        <t/>

        <section title="MA Bootstrapping">
          <t>Section 5.1 provides the communication model for the
          Bootstrapping process.</t>

          <t>Although the specification of mechanisms for Bootstrapping the MA
          are beyond the initial LMAP work scope, designers should recognize
          that the Bootstrapping process is extremely powerful and could cause
          an MA to join a new or different LMAP system with a different
          Controller and Collector, or simply install new Metrics with
          associated Measurement Methods (for example to record DNS queries).
          A Bootstrap attack could result in a breach of the LMAP system with
          significant sensitive information exposure depending on the
          capabilities of the MA, so sufficient security protections are
          warranted.</t>

          <t>The Bootstrapping process provides sensitive information about
          the LMAP system and the organisation that operates it, such as <list
              style="symbols">
              <t>Initial Controller IP address or FQDN</t>

              <t>Assigned Controller IP address or FQDN</t>

              <t>Security certificates and credentials</t>
            </list></t>

          <t>During the Bootstrap process for an MA located at a single
          subscriber's service demarcation point, the MA receives a MA-ID
          which is a persistent pseudonym for the Subscriber. Thus, the MA-ID
          is considered sensitive information because it could provide the
          link between Subscriber identification and Measurements Results.</t>

          <t>Also, the Bootstrap process could assign a Group-ID to the MA.
          The specific definition of information represented in a Group-ID is
          to be determined, but several examples are envisaged including use
          as a pseudonym for a set of Subscribers, a class of service, an
          access technology, or other important categories. Assignment of a
          Group-ID enables anonymisation sets to be formed on the basis of
          service type/grade/rates. Thus, the mapping between Group-ID and
          MA-ID is considered sensitive information.</t>
        </section>

        <section title="Controller &lt;-&gt; Measurement Agent">
          <t>The high-level communication model for interactions between the
          LMAP Controller and Measurement Agent is illustrated in Section 5.2.
          The primary purpose of this exchange is to authenticate and task a
          Measurement Agent with Measurement Instructions, which the
          Measurement Agent then acts on autonomously.</t>

          <t>Primarily IP addresses and pseudonyms (MA-ID, Group-ID) are
          exchanged with a capability request, then measurement-related
          information of interest such as the parameters, schedule, metrics,
          and IP addresses of measurement devices. Thus, the measurement
          Instruction contains sensitive information which must be secured.
          For example, the fact that an ISP is running additional measurements
          beyond the set reported externally is sensitive information, as are
          the additional Measurements Tasks themselves. The Measurement
          Schedule is also sensitive, because an attacker intending to bias
          the results without being detected can use this information to great
          advantage.</t>

          <t>An organisation operating the Controller having no service
          relationship with a user who hosts the Measurement Agent *could*
          gain real-name mapping to a public IP address through user
          participation in an LMAP system (this applies to the Measurement
          Collection protocol, as well).</t>
        </section>

        <section title="Collector &lt;-&gt; Measurement Agent">
          <t>The high-level communication model for interactions between the
          Measurement Agent and Collector is illustrated in Section 5.4. The
          primary purpose of this exchange is to authenticate and collect
          Measurement Results from a MA, which the MA has measured
          autonomously and stored.</t>

          <t>The Measurement Results are the additional sensitive information
          included in the Collector-MA exchange. Organisations collecting LMAP
          measurements have the responsibility for data control. Thus, the
          Results and other information communicated in the Collector protocol
          must be secured.</t>
        </section>

        <section title="Measurement Peer &lt;-&gt; Measurement Agent ">
          <t>A Measurement Method involving a Measurement Peer (or second
          Measurement Agent) raises potential privacy issues, although the
          specification of the mechanisms is beyond the scope of the initial
          LMAP work. The high-level communications model below illustrates the
          various exchanges to execute such a Measurement Method and store the
          Results.</t>

          <t>We note the potential for additional observers in the figures
          below by indicating the possible presence of a NAT, which has
          additional significance to the protocols and direction of
          initiation.</t>

          <t>The various messages are optional, depending on the nature of the
          Measurement Method. It may involve sending Measurement Traffic from
          the Measurement Peer to MA, MA to Measurement Peer, or both.
          Similarly, a second (or more) MAs may be involved.<figure>
              <artwork><![CDATA[ _________________                              _________________
|                 |                            |                 |
|Measurement Peer |=========== NAT ? ==========|Measurement Agent|
|_________________|                            |_________________|

                               <-              (Key Negotiation &
                                               Encryption Setup)
(Encrypted Channel             ->
Established)
(Announce capabilities         ->
& status)
                               <-              (Select capabilities)
ACK                            ->
                               <-              (Measurement Request
                                              (MA+MP IPAddrs,set of
                                                Metrics, Schedule))
ACK                            ->

Measurement Traffic            <>              Measurement Traffic
(may/may not be encrypted)               (may/may not be encrypted)

                               <-            (Stop Measurement Task)

Measurement Results            ->
(if applicable)
                               <-               ACK, Close
]]></artwork>
            </figure>This exchange primarily exposes the IP addresses of
          measurement devices and the inference of measurement participation
          from such traffic. There may be sensitive information on key points
          in a service provider's network included. There may also be access
          to measurement-related information of interest such as the Metrics,
          Schedule, and intermediate results carried in the Measurement
          Traffic (usually a set of timestamps).</t>

          <t>If the Measurement Traffic is unencrypted, as found in many
          systems today, then both timing and limited results are open to
          on-path observers.</t>
        </section>

        <section title="Measurement Agent ">
          <t>Some Measurement Methods only involve a single Measurement Agent.
          They raise potential privacy issues, although the specification of
          the mechanisms is beyond the scope of the initial LMAP work.</t>

          <t>The high-level communications model below illustrates the
          collection of user information of interest with the Measurement
          Agent performing the monitoring and storage of the Results. This
          particular exchange is for measurement of DNS Response Time, which
          most frequently uses UDP transport.</t>

          <t><figure>
              <artwork><![CDATA[ _________________                                      ____________
|                 |                                    |            |
|  DNS Server     |=========== NAT ? ==========*=======| User client|
|_________________|                            ^       |____________|
                                         ______|_______
                                        |              |
                                        |  Measurement |
                                        |    Agent     |
                                        |______________|

                               <-              Name Resolution Req
                                              (MA+MP IPAddrs, 
                                               Desired Domain Name)
Return Record                  ->

]]></artwork>
            </figure></t>

          <t>This exchange primarily exposes the IP addresses of measurement
          devices and the intent to communicate with or access the services of
          "Domain Name". There may be information on key points in a service
          provider's network, such as the address of one of its DNS servers.
          The Measurement Agent may be embedded in the user host, or it may be
          located in another device capable of observing user traffic.</t>

          <t>In principle, any of the user sensitive information of interest
          (listed above) can be collected and stored in the monitoring
          scenario and so must be secured.</t>

          <t>It would also be possible for a Measurement Agent to source the
          DNS query itself. But then there are few privacy concerns.</t>

          <t/>
        </section>

        <section title="Storage and Reporting of Measurement Results">
          <t>Although the mechanisms for communicating results (beyond the
          initial Collector) are beyond the initial LMAP work scope, there are
          potential privacy issues related to a single organisation's storage
          and reporting of Measurement Results. Both storage and reporting
          functions can help to preserve privacy by implementing the
          mitigations described below.</t>
        </section>
      </section>

      <section title="Threats">
        <t>This section indicates how each of the threats described in <xref
        target="RFC6973"/> apply to the LMAP entities and their communication
        and storage of "information of interest". Denial of Service (DOS) and
        other attacks described in the Security section represent threats as
        well, and these attacks are more effective when sensitive information
        protections have been compromised.</t>

        <section title="Surveillance">
          <t>Section 5.1.1 of <xref target="RFC6973"/> describes Surveillance
          as the "observation or monitoring of and individual's communications
          or activities." Hence all Measurement Methods that measure user
          traffic are a form of surveillance, with inherent risks.</t>

          <t>Measurement Methods which avoid periods of user transmission
          indirectly produce a record of times when a subscriber or authorised
          user has used their network access service.</t>

          <t>Measurement Methods may also utilise and store a Subscriber's
          currently assigned IP address when conducting measurements that are
          relevant to a specific Subscriber. Since the Measurement Results are
          time-stamped, they could provide a record of IP address assignments
          over time.</t>

          <t>Either of the above pieces of information could be useful in
          correlation and identification, described below.</t>
        </section>

        <section title="Stored Data Compromise">
          <t>Section 5.1.2 of <xref target="RFC6973"/> describes Stored Data
          Compromise as resulting from inadequate measures to secure stored
          data from unauthorised or inappropriate access. For LMAP systems
          this includes deleting or modifying collected measurement records,
          as well as data theft.</t>

          <t>The primary LMAP entity subject to compromise is the repository,
          which stores the Measurement Results; extensive security and privacy
          threat mitigations are warranted. The Collector and MA also store
          sensitive information temporarily, and need protection. The
          communications between the local storage of the Collector and the
          repository is beyond the scope of the initial LMAP work, though this
          communications channel will certainly need protection as well as the
          mass storage itself.</t>

          <t>The LMAP Controller may have direct access to storage of
          Subscriber information (location, billing, service parameters, etc.)
          and other information which the controlling organisation considers
          private, and again needs protection.</t>

          <t>Note that there is tension between the desire to store all raw
          results in the LMAP Collector (for reproducibility and custom
          analysis), and the need to protect the privacy of measurement
          participants. Many of the compromise mitigations described in
          section 8.6 below are most efficient when deployed at the MA,
          therefore minimising the risks with stored results.</t>
        </section>

        <section title="Correlation and Identification">
          <t>Sections 5.2.1 and 5.2.2 of <xref target="RFC6973"/> describe
          Correlation as combining various pieces of information to obtain
          desired characteristics of an individual, and Identification as
          using this combination to infer identity.</t>

          <t>The main risk is that the LMAP system could unwittingly provide a
          key piece of the correlation chain, starting with an unknown
          Subscriber's IP address and another piece of information. For
          example, a Subscriber utilised Internet access from 2000 to 2310
          UTC, because the Measurement Tasks were deferred, or sent a name
          resolution for www.example.com at 2300 UTC.</t>
        </section>

        <section title="Secondary Use and Disclosure">
          <t>Sections 5.2.3 and 5.2.4 of <xref target="RFC6973"/> describes
          Secondary Use as unauthorised utilisation of an individual's
          information for a purpose the individual did not intend, and
          Disclosure is when such information is revealed causing other's
          notions of the individual to change, or confidentiality to be
          violated.</t>

          <t>Measurement Methods that measure user traffic are a form of
          Secondary Use, and the Subscribers' permission should be obtained
          beforehand. It may be necessary to obtain the measured ISP's
          permission to conduct measurements, for example when required by the
          terms and conditions of the service agreement, and notification is
          considered good measurement practice.</t>

          <t>For Measurement Methods that measure Measurement Traffic the
          Measurement Results provide some limited information about the
          Subscriber or ISP and could result in Secondary Uses. For example,
          the use of the Results in unauthorised marketing campaigns would
          qualify as Secondary Use. Secondary use may break national laws and
          regulations, and may violate individual's expectations or
          desires.</t>
        </section>
      </section>

      <section title="Mitigations">
        <t>This section examines the mitigations listed in section 6 of <xref
        target="RFC6973"/> and their applicability to LMAP systems. Note that
        each section in <xref target="RFC6973"/> identifies the threat
        categories that each technique mitigates.</t>

        <section title="Data Minimisation">
          <t>Section 6.1 of <xref target="RFC6973"/> encourages collecting and
          storing the minimal information needed to perform a task.</t>

          <t>LMAP results can be useful for general reporting about
          performance and for specific troubleshooting. They need different
          levels of information detail, as explained in the paragraphs
          below.</t>

          <t>For general results, the results can be aggregated into large
          categories (the month of March, all subscribers West of the
          Mississippi River). In this case, all individual identifications
          (including IP address of the MA) can be excluded, and only relevant
          results are provided. However, this implies a filtering process to
          reduce the information fields, because greater detail was needed to
          conduct the Measurement Tasks in the first place.</t>

          <t>For troubleshooting, so that a network operator or end user can
          identify a performance issue or failure, potentially all the network
          information (IP addresses, equipment IDs, location), Measurement
          Schedule, service configuration, Measurement Results, and other
          information may assist in the process. This includes the information
          needed to conduct the Measurements Tasks, and represents a need
          where the maximum relevant information is desirable, therefore the
          greatest protections should be applied. This level of detail is
          greater than needed for general performance monitoring.</t>

          <t>As regards Measurement Methods that measure user traffic, we note
          that a user may give temporary permission (to enable detailed
          troubleshooting), but withhold permission for them in general. Here
          the greatest breadth of sensitive information is potentially
          exposed, and the maximum privacy protection must be provided. The
          Collector may perform pre-storage minimisation and other mitigations
          (below) to help preserve privacy.</t>

          <t>For MAs with access to the sensitive information of users (e.g.,
          within a home or a personal host/handset), it is desirable for the
          results collection to minimise the data reported, but also to
          balance this desire with the needs of troubleshooting when a service
          subscription exists between the user and organisation operating the
          measurements.</t>
        </section>

        <section title="Anonymity">
          <t>Section 6.1.1 of <xref target="RFC6973"/> describes a way in
          which anonymity is achieved: "there must exist a set of individuals
          that appear to have the same attributes as the individual", defined
          as an "anonymity set".</t>

          <t>Experimental methods for anonymisation of user identifiable data
          (and so particularly applicable to Measurement Methods that measure
          user traffic) have been identified in <xref target="RFC6235"/>.
          However, the findings of several of the same authors is that "there
          is increasing evidence that anonymisation applied to network trace
          or flow data on its own is insufficient for many data protection
          applications as in <xref target="Bur10"/>." Essentially, the details
          of such Measurement Methods can only be accessed by closed
          organisations, and unknown injection attacks are always less
          expensive than the protections from them. However, some forms of
          summary may protect the user's sensitive information sufficiently
          well, and so each Metric must be evaluated in the light of
          privacy.</t>

          <t>The techniques in <xref target="RFC6235"/> could be applied more
          successfully in Measurement Methods that generate Measurement
          Traffic, where there are protections from injection attack. The
          successful attack would require breaking the integrity protection of
          the LMAP Reporting Protocol and injecting Measurement Results (known
          fingerprint, see section 3.2 of <xref target="RFC6973"/>) for
          inclusion with the shared and anonymised results, then
          fingerprinting those records to ascertain the anonymisation
          process.</t>

          <t>Beside anonymisation of measured Results for a specific user or
          provider, the value of sensitive information can be further diluted
          by summarising the results over many individuals or areas served by
          the provider. There is an opportunity enabled by forming anonymity
          sets <xref target="RFC6973"/> based on the reference path
          measurement points in <xref target="I-D.ietf-ippm-lmap-path"/>. For
          example, all measurements from the Subscriber device can be
          identified as "mp000", instead of using the IP address or other
          device information. The same anonymisation applies to the Internet
          Service Provider, where their Internet gateway would be referred to
          as "mp190".</t>
        </section>

        <section title="Pseudonymity">
          <t>Section 6.1.2 of <xref target="RFC6973"/> indicates that
          pseudonyms, or nicknames, are a possible mitigation to revealing
          one's true identity, since there is no requirement to use real names
          in almost all protocols.</t>

          <t>A pseudonym for a measurement device's IP address could be an
          LMAP-unique equipment ID. However, this would likely be a permanent
          handle for the device, and long-term use weakens a pseudonym's power
          to obscure identity.</t>
        </section>

        <section title="Other Mitigations">
          <t>Data can be de-personalised by blurring it, for example by adding
          synthetic data, data-swapping, or perturbing the values in ways that
          can be reversed or corrected.</t>

          <t>Sections 6.2 and 6.3 of <xref target="RFC6973"/> describe User
          Participation and Security, respectively.</t>

          <t>Where LMAP measurements involve devices on the Subscriber's
          premises or Subscriber-owned equipment, it is essential to secure
          the Subscriber's permission with regard to the specific information
          that will be collected. The informed consent of the Subscriber (and,
          if different, the end user) may be needed, including the specific
          purpose of the measurements. The approval process could involve
          showing the Subscriber their measured information and results before
          instituting periodic collection, or before all instances of
          collection, with the option to cancel collection temporarily or
          permanently.</t>

          <t>It should also be clear who is legally responsible for data
          protection (privacy); in some jurisdictions this role is called the
          'data controller'. It is always good practice to limit the time of
          personal information storage.</t>

          <t>Although the details of verification would be impenetrable to
          most subscribers, the MA could be architected as an "app" with open
          source-code, pre-download and embedded terms of use and agreement on
          measurements, and protection from code modifications usually
          provided by the app-stores. Further, the app itself could provide
          data reduction and temporary storage mitigations as appropriate and
          certified through code review.</t>

          <t>LMAP protocols, devices, and the information they store clearly
          need to be secure from unauthorised access. This is the hand-off
          between privacy and security considerations (Section 7). The Data
          Controller has the (legal) responsibility to maintain data
          protections described in the Subscriber's agreement and agreements
          with other organisations.</t>

          <t/>
        </section>
      </section>
    </section>

    <section title="IANA Considerations">
      <t>There are no IANA considerations in this memo.</t>
    </section>

    <section title="Appendix: Deployment examples">
      <t>In this section we describe some deployment scenarios that are
      feasible within the LMAP framework defined in this document.</t>

      <t>The LMAP framework defines two types of components involved in the
      actual measurement task, namely the Measurement Agent (MA) and the
      Measurement Peer (MP). The fundamental difference conveyed in the
      definition of these terms is that the MA has a interface with the
      Controller/Collector while the MP does not. The MP is broadly defined as
      a function that assists the MA in the Measurement Task but has no
      interface with the Controller/Collector. There are many elements in the
      network that can fall into this broad definition of MP. We believe that
      the MP terminology is useful to allow us to refer an element of the
      network that plays a role that is conceptually important to understand
      and describe the measurement task being performed. We next illustrate
      these concepts by describing several deployment scenarios.</t>

      <t>A very simple example of a Measurement Peer is a web server that the
      MA is downloading a web page from (such as www.example.com) in order to
      perform a speed test. The web server is a MP and from its perspective,
      the MA is just another client; the MP doesn't have a specific function
      for assisting measurements. This is described in the figure A1.<figure>
          <artwork><![CDATA[                                                         ^
   +----------------+  Web Traffic +----------------+  IPPM
   |   Web Client   |<------------>| MP: Web Server |  Scope
   |                |              +----------------+    |
...|................|....................................V...  
   | LMAP interface |                                    ^
   +----------------+                                    |
            ^     |                                      |
Instruction |     |  Report                              |
            |     +-----------------+                    |
            |                       |                    |
            |                       v                   LMAP
       +------------+             +------------+        Scope
       | Controller |             |  Collector |         |
       +------------+             +------------+         V

Figure A1: Schematic of LMAP-based measurement system,
with Web server as Measurement Peer
]]></artwork>
        </figure></t>

      <t>Another case that is slightly different than this would be the one of
      a TWAMP-responder. This is also a MP, with a helper function, the TWAMP
      server, which is specially deployed to assist the MAs that perform TWAMP
      tests. Another example is with a ping server, as described in Section
      2.</t>

      <t>A further example is the case of a traceroute like measurement. In
      this case, for each packet sent, the router where the TTL expires is
      performing the MP function. So for a given Measurement Task, there is
      one MA involved and several MPs, one per hop.</t>

      <t>In figure A2 we depict the case of an OWAMP responder acting as an
      MP. In this case, the helper function in addition reports results back
      to the MA. So it has both a data plane and control interface with the
      MA.</t>

      <t/>

      <figure>
        <artwork><![CDATA[   +----------------+    OWAMP     +----------------+    ^
   | OWAMP          |<--control--->| MP:            |    |
   | control-client |>test-traffic>| OWAMP server & |   IPPM
   | fetch-client & |<----fetch----| session-rec'ver|  Scope
   | session-sender |              |                |    |
   |                |              +----------------+    |
...|................|....................................v...  
   | LMAP interface |                                    ^
   +----------------+                                    |
            ^     |                                      |
Instruction |     |  Report                              |
            |     +-----------------+                    |
            |                       |                    |
            |                       v                  LMAP
       +------------+             +------------+       Scope
       | Controller |             |  Collector |         |
       +------------+             +------------+         v
                                                       IPPM

Figure A2: Schematic of LMAP-based measurement system,
with OWAMP server as Measurement Peer
]]></artwork>
      </figure>

      <t>However, it is also possible to use two Measurement Agents when
      performing one way Measurement Tasks, as described in figure A3 below.
      In this case, MA1 generates the traffic and MA2 receives the traffic and
      send the reports to the Collector. Note that both MAs are instructed by
      the Controller. MA1 receives an Instruction to send the traffic and MA2
      receives an Instruction to measured the received traffic and send
      Reports to the Collector.</t>

      <t/>

      <figure>
        <artwork><![CDATA[   +----------------+              +----------------+    ^
   |  MA1           |              |  MA2           |  IPPM
   | iperf -u sender|-UDP traffic->| iperf -u recvr |  Scope
   |                |              |                |    v
...|................|..............|................|....v...  
   | LMAP interface |              | LMAP interface |    ^
   +----------------+              +----------------+    |
            ^                        ^   |               |
Instruction |    Instruction{Report} |   | Report        |
{task,      |    +-------------------+   |               |
 schedule}  |    |                       |               |
            |    |                       v              LMAP
       +------------+             +------------+       Scope
       | Controller |             |  Collector |         |
       +------------+             +------------+         v
                                                       IPPM

Figure A3: Schematic of LMAP-based measurement system,
with two Measurement Agents cooperating to measure UDP traffic
]]></artwork>
      </figure>

      <t/>

      <t>Next, we consider Measurement Methods that measure user traffic.
      Traffic generated in one point in the network flowing towards a given
      destination and the traffic is observed in some point along the path.
      One way to implement this is that the endpoints generating and receiving
      the traffic are not instructed by the Controller; hence they are MPs.
      The MA is located along the path with a monitor function that measures
      the traffic. The MA is instructed by the Controller to monitor that
      particular traffic and to send the Report to the Collector. It is
      depicted in figure A4 below.</t>

      <t/>

      <figure>
        <artwork><![CDATA[+-----+   +----------------+              +------+   ^   
| MP  |   |  MA: Monitor   |              | MP   | IPPM
|     |<--|----------------|---traffic--->|      | Scope
+-----+   |                |              +------+   |
   .......|................|.........................v...........  
          | LMAP interface |                                ^
          +----------------+                                |
                     ^     |                                |
         Instruction |     |  Report                        |
                     |     +-----------------+              |
                     |                       |              |
                     |                       v             LMAP
               +------------+             +------------+   Scope
               | Controller |             |  Collector |    |
               +------------+             +------------+    v


Figure A4: Schematic of LMAP-based measurement system,
with a Measurement Agent monitoring traffic
]]></artwork>
      </figure>

      <t/>

      <t>Finally, we should consider the case of a router or a switch along
      the measurement path. This certainly performs an important role in the
      measurement - if packets are not forwarded, the measurement task will
      not work. Whilst it doesn't has an interface with the Controller or
      Collector, and so fits into the definition of MP, usually it is not
      particularly useful to highlight it as a MP.</t>

      <t/>
    </section>

    <section title="Acknowledgments">
      <t>This document is a merger of three individual drafts:
      draft-eardley-lmap-terminology-02, draft-akhter-lmap-framework-00, and
      draft-eardley-lmap-framework-02.</t>

      <t>Thanks to Juergen Schoenwaelder for his detailed review of the
      terminology. Thanks to Charles Cook for a very detailed review of -02.
      Thanks to Barbara Stark and Ken Ko for many helpful comments about later
      versions.</t>

      <t>Thanks to numerous people for much discussion, directly and on the
      LMAP list (apologies to those unintentionally omitted): Alan Clark,
      Alissa Cooper, Andrea Soppera, Barbara Stark, Benoit Claise, Brian
      Trammell, Charles Cook, Dave Thorne, Frode S&oslash;rensen, Greg Mirsky,
      Guangqing Deng, Jason Weil, Jean-Francois Tremblay, Jerome Benoit,
      Joachim Fabini, Juergen Schoenwaelder, Jukka Manner, Ken Ko, Lingli
      Deng, Mach Chen, Marc Ibrahim, Michael Bugenhagen, Michael Faath, Nalini
      Elkins, Rolf Winter, Sam Crawford, Sharam Hakimi, Steve Miller, Ted
      Lemon, Timothy Carey, Vaibhav Bajpai, Vero Zheng, William Lupton.</t>

      <t>Philip Eardley, Trevor Burbridge and Marcelo Bagnulo work in part on
      the Leone research project, which receives funding from the European
      Union Seventh Framework Programme [FP7/2007-2013] under grant agreement
      number 317647.</t>

      <t/>

      <t/>
    </section>

    <section title="History">
      <t>First WG version, copy of draft-folks-lmap-framework-00.</t>

      <t/>

      <section title="From -00 to -01">
        <t><list style="symbols">
            <t>new sub-section of possible use of Group-IDs for privacy</t>

            <t>tweak to definition of Control protocol</t>

            <t>fix typo in figure in S5.4</t>
          </list></t>
      </section>

      <section title="From -01 to -02">
        <t><list style="symbols">
            <t>change to INFORMATIONAL track (previous version had typo'd
            Standards track)</t>

            <t>new definitions for Capabilities Information and Failure
            Information</t>

            <t>clarify that diagrams show LMAP-level information flows.
            Underlying protocol could do other interactions, eg to get through
            NAT or for Collector to pull a Report</t>

            <t>add hint that after a re-boot should pause random time before
            re-register (to avoid mass calling event)</t>

            <t>delete the open issue "what happens if a Controller fails"
            (normal methods can handle)</t>

            <t>add some extra words about multiple Tasks in one Schedule</t>

            <t>clarify that new Schedule replaces (rather than adds to) and
            old one. Similarly for new configuration of Measurement Tasks or
            Report Channels.</t>

            <t>clarify suppression is temporary stop; send a new Schedule to
            permanently stop Tasks</t>

            <t>alter suppression so it is ACKed</t>

            <t>add un-suppress message</t>

            <t>expand the text on error reporting, to mention Reporting
            failures (as well as failures to action or execute Measurement
            Task &amp; Schedule)</t>

            <t>add some text about how to have Tasks running indefinitely</t>

            <t>add that optionally a Report is not sent when there are no
            Measurement Results</t>

            <t>add that a Measurement Task may create more than one
            Measurement Result</t>

            <t>clarify /amend /expand that Reports include the "raw"
            Measurement Results - any pre-processing is left for lmap2.0</t>

            <t>add some cautionary words about what if the Collector
            unexpectedly doesn't hear from a MA</t>

            <t>add some extra words about the potential impact of Measurement
            Tasks</t>

            <t>clarified various aspects of the privacy section</t>

            <t>updated references</t>

            <t>minor tweaks</t>
          </list></t>
      </section>

      <section title="From -02 to -03">
        <t><list style="symbols">
            <t>alignment with the Information Model
            [burbridge-lmap-information-model] as this is agreed as a WG
            document</t>

            <t>One-off and periodic Measurement Schedules are kept separate,
            so that they can be updated independently</t>

            <t>Measurement Suppression in a separate sub-section. Can now
            optionally include particular Measurement Tasks &amp;/or Schedules
            to suppress, and start/stop time</t>

            <t>for clarity, concept of Channel split into Control, Report and
            MA-to-Controller Channels</t>

            <t>numerous editorial changes, mainly arising from a very detailed
            review by Charles Cook</t>

            <t/>
          </list></t>
      </section>

      <section title="From -03 to -04">
        <t><list style="symbols">
            <t>updates following the WG Last Call, with the proposed consensus
            on the various issues as detailed in
            http://tools.ietf.org/agenda/89/slides/slides-89-lmap-2.pdf. In
            particular:</t>

            <t>tweaked definitions, especially of Measurement Agent and
            Measurement Peer</t>

            <t>Instruction - left to each implementation &amp; deployment of
            LMAP to decide on the granularity at which an Instruction Message
            works</t>

            <t>words added about overlapping Measurement Tasks (measurement
            system can handle any way they choose; Report should mention if
            the Task overlapped with another)</t>

            <t>Suppression: no defined impact on Passive Measurement Task;
            extra option to suppress on-going Active Measurement Tasks;
            suppression doesn't go to Measurement Peer, since they don't
            understand Instructions</t>

            <t>new concept of Data Transfer Task (and therefore adjustment of
            the Channel concept)</t>

            <t>enhancement of Results with Subscriber's service parameters -
            could be useful, don't define how but can be included in Report to
            various other sections</t>

            <t>various other smaller improvements, arising from the WGLC</t>

            <t>Appendix added with examples of Measurement Agents and Peers in
            various deployment scenarios. To help clarify what these terms
            mean.</t>
          </list></t>
      </section>

      <section title="From -04 to -05">
        <t><list style="symbols">
            <t>clarified various scoping comments by using the phrase "scope
            of initial LMAP work" (avoiding "scope of LMAP WG" since this may
            change in the future)</t>

            <t>added a Configuration Protocol - allows the Controller to
            update the MA about information that it obtained during the
            bootstrapping process (for consistency with Information Model)</t>

            <t>Removed over-detailed information about the relationship
            between the different items in Instruction, as this seems more
            appropriate for the information model. Clarified that the lists
            given are about the aims and not a list of information elements
            (these will be defined in draft-ietf-information-model).</t>

            <t>the Measurement Method, specified as a URI to a registry entry
            - rather than a URN</t>

            <t>MA configured with time limit after which, if it hasn't heard
            from Controller, then it stops running Measurement Tasks (rather
            than this being part of a Schedule)</t>

            <t>clarified there is no distinction between how capabilities,
            failure and logging information are transferred (all can be when
            requested by Controller or by MA on its own initiative).</t>

            <t>removed mention of Data Transfer Tasks. This abstraction is
            left to the information model i-d</t>

            <t>added Deployment sub-section about Measurement Agent embedded
            in ISP Network</t>

            <t>various other smaller improvements, arising from the 2nd
            WGLC</t>
          </list></t>
      </section>

      <section title="From -05 to -06">
        <t><list style="symbols">
            <t>clarified terminlogy around Measurement Methods and Tasks.
            Since within a Method there may be several different roles
            (requester and responder, for instance)</t>

            <t>Suppression: there is now the concept of a flag (boolean) which
            indicates whether a Task is by default gets suppressed or not. The
            optional suppression message (with list of specific tasks
            /schedules to suppress) over-rides this flag.</t>

            <t>The previous bullet also means there is no need to make a
            distinction between active and passive Measurement Tasks, so this
            distinction is removed.</t>

            <t>removed Configuration Protocol &ndash; Configuration is part of
            the Instruction and so uses the Control Protocol.</t>
          </list></t>
      </section>

      <section title="From -06 to -07">
        <t><list style="symbols">
            <t>Clarifications and nits</t>
          </list></t>
      </section>
    </section>
  </middle>

  <back>
    <references title="Informative References">
      <reference anchor="Bur10">
        <front>
          <title>The Role of Network Trace anonymisation Under Attack</title>

          <author initials="M" surname="Burkhart">
            <organization>Burkhart</organization>
          </author>

          <author initials="D" surname="Schatzmann">
            <organization/>
          </author>

          <author initials="B" surname="Trammell">
            <organization/>
          </author>

          <author initials="E" surname="Boschi">
            <organization>ACM Computer Communications Review, vol. 40, no. 1,
            pp. 6-11</organization>
          </author>

          <date month="January" year="2010"/>
        </front>
      </reference>

      <reference anchor="TR-069">
        <front>
          <title>CPE WAN Management Protocol</title>

          <author fullname="Broadband Forum" initials="" surname="TR-069">
            <!---->

            <organization abbrev="Boeing">Boeing Computer
            Services</organization>
          </author>

          <date month="November" year="2013"/>
        </front>

        <seriesInfo name=""
                    value="http://www.broadband-forum.org/technical/trlist.php"/>
      </reference>

      <reference anchor="UPnP">
        <front>
          <title>UPnP Device Architecture and UPnP Device Control Protocols
          specifications</title>

          <author fullname="UPnP Forum" initials="" surname="ISO/IEC 29341-x">
            <!---->

            <organization abbrev="Boeing">Boeing Computer
            Services</organization>
          </author>

          <date month="" year="2011"/>
        </front>

        <seriesInfo name=""
                    value="http://upnp.org/sdcps-and-certification/standards/"/>
      </reference>

      <?rfc include='reference.RFC.1035'?>

      <?rfc include='reference.RFC.4101'?>

      <?rfc include='reference.RFC.4122'?>

      <?rfc ?>

      <?rfc include='reference.I-D.ietf-lmap-use-cases'?>

      <?rfc include='reference.I-D.manyfolks-ippm-metric-registry'?>

      <?rfc include='reference.I-D.ietf-homenet-arch'?>

      <?rfc include='reference.RFC.6419'?>

      <?rfc include='reference.RFC.6887'?>

      <?rfc include='reference.I-D.ietf-lmap-information-model'?>

      <?rfc include='reference.RFC.6235'?>

      <?rfc include='reference.RFC.6973'?>

      <?rfc include='reference.I-D.ietf-ippm-lmap-path'?>

      <?rfc include='reference.RFC.4656'?>

      <?rfc include='reference.RFC.5357'?>

      <?rfc include='reference.RFC.3444'?>
    </references>
  </back>
</rfc>
