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<rfc category="info" docName="draft-ietf-lmap-framework-02" ipr="trust200902"
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  <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">British Telecom</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">British Telecom</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="6" month="December" year="2013"/>

    <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 players
      and home gateways, or simply dedicated probes. It is expected that such
      a system could easily comprise 100k devices. 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 at <xref
      target="I-D.ietf-lmap-use-cases"/>. The LMAP framework should be useful
      for these, as well as other use cases that the LMAP WG doesn't
      concentrate on, such as to help end users run diagnostic checks like a
      network speed test.</t>

      <t>The LMAP framework has four basic elements: Measurement Agents,
      Measurement Peers, Controllers and Collectors.</t>

      <t>Measurement Agents (MAs) perform network measurements. They are
      pieces of code that can be executed in specialized hardware (hardware
      probe) or on a general-purpose device (like a PC or mobile phone). The
      Measurement Agents may have multiple interfaces (WiFi, Ethernet, DSL,
      fibre, etc.) and the measurements may specify any one of these.
      Measurements may be active (the MA or Measurement Peer (MP) generates
      test traffic), passive (the MA observes user traffic), or some hybrid
      form of the two. For active measurement tasks, the MA (or MP) generates
      test traffic and measures some metric associated with its transfer over
      the path to (or from) a Measurement Peer. For example, one active
      measurement task could be to measure the UDP latency between the MA and
      a given MP. MAs may also conduct passive testing through the observation
      of traffic. The measurements themselves may be on IPv4, IPv6, and on
      various services (DNS, HTTP, XMPP, FTP, VoIP, etc.).</t>

      <t>The Controller manages one or more MAs by instructing it which
      measurement tasks it should perform and when. For example it may
      instruct a MA at a home gateway: &ldquo;Measure the &lsquo;UDP
      latency&rsquo; with the Measurement Peer mp.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.</t>

      <t>There are additional elements that are part of a measurement system,
      but that are out of the scope for LMAP. We provide a detailed discussion
      of all the elements in the rest of the document.</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 tests that they perform, the
          components, the data models and protocols for transferring
          information between the components. For example so that it is
          meaningful to compare measurements made of the same metric at
          different times and places. For example so that the operator of a
          measurement system can buy 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. Existing systems have up to a
          few thousand Measurement Agents (without judging how much further
          they could scale).</t>

          <t>Diversity - a measurement system should handle different types of
          Measurement Agent - for example Measurement Agents may come from
          different vendors, be in wired and wireless networks 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 LMAP. In this section we provide an overview on the whole
      measurement system and we introduce the main terms needed for the LMAP
      framework. The new terms are capitalized. In the next section we provide
      a terminology section with a compilation of all the LMAP terms and their
      definition. The subsequent sections study the LMAP components in more
      detail.</t>

      <t>A Measurement Task measures some performance or reliability Metric of
      interest. An Active Measurement Task involves either a Measurement Agent
      (MA) injecting Test Traffic into the network destined for a Measurement
      Peer (MP), and/or a MP sending Test Traffic to a MA; one of them
      measures the some parameter associated with the transfer of the
      packet(s). A Passive Measurement Task involves only a MA, which simply
      observes existing traffic - for example, it could simply count bytes or
      it might calculate the average loss for a particular flow.</t>

      <t>It is very useful to standardise Measurement Methods (a Measurement
      Method is a generalisation of a Measurement Task), 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.bagnulo-ippm-new-registry-independent"/> so that a
      Measurement Method can be referred to simply by its identifier in the
      registry. The Measurement Methods and registry would hopefully also be
      referenced by other standards organisations.</t>

      <t>In order for a Measurement Agent and a Measurement Peer to execute an
      Active Measurement Task, they exchange Active Measurement Traffic. The
      protocols used for the Active Measurement Traffic is out of the scope of
      the LMAP WG and falls within the scope of other IETF WGs such as
      IPPM.</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
      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>The next components we consider are the Measurement Agent (MA),
      Controller and Collector. The main work of the LMAP working group is to
      define the Control Protocol between the Controller and MA, and the
      Report Protocol between the MA and Collector. Section 4 onwards
      considers the LMAP compnents in more detail; here we introduce them.</t>

      <t>The Controller manages a MA by instructing it which Measurement Tasks
      it should perform and when. For example it may instruct a MA at a home
      gateway: &ldquo;Run the &lsquo;download speed test&rsquo; with the
      Measurement Peer at the end user's first IP point in the network; if the
      end user is active then delay the test and re-try 1 minute later, with
      up to 3 re-tries; repeat every hour at xx.05 + Unif[0,180]
      seconds&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 + Unif[0,180] seconds; if the end user is
      active then delay the report 5 minutes&rdquo;. As well as regular
      Measurement Tasks, a Controller can initiate a one-off Measurement Task
      ("Do measurement now", "Report as soon as possible"). These are called
      the Measurement and Report Schedule.</t>

      <t>The Collector accepts a Report from a MA with the results from its
      tests. It may also do some processing on the results &ndash; for
      instance to eliminate outliers, as they can severely impact the
      aggregated results.</t>

      <t>Finally we introduce several components that are out of scope of the
      LMAP WG 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 WG considers
      the boostrap process, since it affects the Information Model. However,
      it does not define a bootstrap protocol, since it is likely to be
      technology specific and could be defined by the Broadband Forum, DOCSIS
      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).</t>

      <t>A Subscriber Parameter Database contains information about the line,
      for example 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 are all factors
      which 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. Another
      example is if the Controller wants to run a one-off Measurement Task to
      diagnose a fault, then it should understand what problem the customer is
      experiencing and what Measurement Tasks have already been run. The
      Subscribers' service parameters are already gathered and stored by
      existing operations systems.</t>

      <t>A Results Repository records all measurements in an equivalent form,
      for example an SQL database, so that they can be easily accessed by the
      Data Analysis Tools. The Data Analysis Tools also need to understand the
      Subscriber's service information, for example the broadband
      contract.</t>

      <t>The Data Analysis Tools receive the results from the Collector or via
      the Results Database. They might visualise the data or identify which
      component or link is likely to be the cause of a fault or
      degradation.</t>

      <t>The operator's OAM (Operations, Administration, and Maintenance) uses
      the results from the tools.</t>

      <t/>

      <t/>

      <figure>
        <artwork><![CDATA[                                                           ^
                                                              |
                                                              IPPM
            +---------------+   Test     +-------------+      Scope
   +------->| Measurement   |<---------->| Measurement |      v
   |        |   Agent       |   Traffic  |     Peer    |      ^
   |        +---------------+            +-------------+      |
   |              ^      |                                    |
   |  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 the LMAP WG)
]]></artwork>
      </figure>
    </section>

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

      <t>Active Measurement Method (Task): A type of Measurement Method (Task)
      that involves a Measurement Agent and a Measurement Peer (or possibly
      Peers), where either the Measurement Agent or the Measurement Peer
      injects test packet(s) into the network destined for the other, and
      which involves one of them measuring some performance or reliability
      parameter associated with the transfer of the packet(s).</t>

      <t>Bootstrap Protocol: A protocol that initialises a Measurement Agent
      with the information necessary to be integrated into a measurement
      system.</t>

      <t>Capabilities Information: The list of the Measurement Methods that
      the MA can perform, plus information about the device hosting the MA
      (for example its interface type and speed and its IP address).</t>

      <t>Channel: a schedule, a target and the associated security information
      for that target. In the case of a Report Channel it is a specific Report
      Schedule, a Collector and its associated security information.</t>

      <t>Collector: A function that receives a Report from a Measurement
      Agent. Colloquially, a Collector is a physical device that performs this
      function.</t>

      <t>Controller: A function that provides a Measurement Agent with
      Instruction(s). Colloquially, a Controller is a physical device that
      performs this function.</t>

      <t>Control Protocol: The protocol delivering Instruction(s) from a
      Controller to a Measurement Agent. It also delivers Failure Information
      and Capabilities Information from the Measurement Agent to the
      Controller.</t>

      <t>Cycle-ID: A tag that is sent by the Controller in an Instruction and
      echoed by the MA in its Report; Measurement Results with the same
      Cycle-ID are expected to be comparable.</t>

      <t>Data Model: The implementation of an Information Model in a
      particular data modelling language.</t>

      <t>Derived Metric: A Metric that is a combination of other Metrics,
      and/or a combination of the same Metric measured over different parts of
      the network, or at different times.</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.</t>

      <t>Instruction: The description of Measurement Tasks to perform and the
      details of the Report to send. The Instruction is sent by a Controller
      to a Measurement Agent.</t>

      <t>Measurement Agent (MA): The function that receives Instructions from
      a Controller, performs Measurement Tasks (perhaps in concert with a
      Measurement Peer) and reports Measurement Results to a Collector.
      Colloquially, a Measurement Agent is a physical device that performs
      this function.</t>

      <t>Measurement Method: The process for assessing the value of a Metric;
      the process of measuring some performance or reliability parameter; the
      generalisation of a Measurement Task.</t>

      <t>Measurement Parameter: A parameter whose value is left open by the
      Measurement Method.</t>

      <t>Measurement Peer: The function that receives control messages and
      test packets from a Measurement Agent and may reply to the Measurement
      Agent as defined by the Measurement Method.</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 a series of
      Measurement Tasks.</t>

      <t>Measurement Suppression: a type of Instruction that stops
      (suppresses) Measurement Tasks.</t>

      <t>Measurement Task: The act that yields a single Measurement Result;
      the act consisting of the (single) operation of the Measurement Method
      at a particular time and with all its parameters set to specific
      values.</t>

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

      <t>Passive Measurement Method (Task): A Measurement Method (Task) in
      which a Measurement Agent observes existing traffic at a specific
      measurement point, but does not inject test packet(s).</t>

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

      <t>Report Schedule: the schedule for sending a series of 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. The subscriber is
      allowed to subscribe and un-subscribe services, and to register a user
      or a list of users authorized to enjoy these services. <xref
      target="Q1741"/> Both the subscriber and service provider are allowed to
      set the limits relative to the use that associated users make of
      subscribed services.</t>

      <t>Active Measurement Traffic: for Active Measurement Tasks, the traffic
      generated by the Measurement Agent and/or the Measurement Peer to
      execute the requested Measurement Task.</t>
    </section>

    <section title="Constraints">
      <t>The LMAP framework makes some important assumptions, which constrain
      the scope of the work to be done.</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 both for the
        data and the quality of experience delivered to its users. 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 presents (RFC4101) "an architectural model for how
      the protocol operates ... a short description of the system in overview
      form, ... [which] 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 three
          items below</t>

          <t>a Control Protocol, which delivers an Instruction from a
          Controller and a MA. The Instruction details what Measurement Tasks
          the MA should perform and when, and how it should report the
          Measurement Results</t>

          <t>the actual Measurement Tasks are performed. An Active Measurement
          Task involves sending Active Measurement Traffic between the
          Measurement Agent and a Measurement Peer, whilst a Passive
          Measurement Task involves (only) the Measurement Agent observing
          existing user traffic. The LMAP WG does not define Measurement
          Methods, however the IPPM WG does.</t>

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

      <t>In the diagrams the following convention is used:</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.burbridge-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. The LMAP WG will define a
      specific Control Protocol and Report Protocol, but other Protocols could
      be defined by other standards bodies or be proprietary. However it is
      important that they all implement the same Information and Protocol
      Model, in order to ease the definition, operation and interoperability
      of large-scale measurement systems.</t>

      <t/>

      <t>The diagrams show the flow of LMAP information, however there may
      need to be other protocol interactions. For example, typically the MA is
      behind a NAT, so it needs to initiate communications in order that the
      Controller can communicate with it. The communications channel also
      needs to be secured before it is used. Another example is that the
      Collector may want to 'pull' Measurement Results from a MA.</t>

      <section title="Bootstrapping process">
        <t>The primary purpose of bootstrapping is to enable the MA and
        Controller to be integrated into a measurement system. In order to do
        that, the MA needs to retrieve information about itself (like its
        identity in the measurement system), about the Controller and the
        Collector(s) as well as security information (such as certificates and
        credentials).</t>

        <t><figure>
            <artwork><![CDATA[
                                                     +--------------+
                                                     | Measurement  |
                                                     |  Agent       |
                                                     +--------------+ 
(Initial Controller details:
 address or FQDN,                       ->
 security credentials, MA-ID)

+-----------------+
|    Initial      |
|   Controller    |
+-----------------+
                                       <-              (register)
Controller details:
address or FQDN,                       ->
security credentials

+-----------------+
|                 |
|   Controller    |
+-----------------+            
                                       <-              register 
(MA-ID, Group-ID, report?)             ->

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

        <t/>

        <t>The MA knows how to contact a Controller through some device
        /access specific mechanism. For example, this could be in the
        firmware, downloaded, manually configured or via a protocol like
        TR-069. The Controller could either be the one that will send it
        Instructions (see next sub-section) or else an initial Controller. The
        role of an initial Controller is simply to inform the MA how to
        contact its actual Controller; this could be useful, for example: for
        load balancing; if the details of the initial Controller are
        statically configured; if the measurement system has specific
        Controllers for different devices types; or perhaps as a way of
        handling failure of the Controller.</t>

        <t>If the MA has not learnt its identifier (MA-ID) while
        bootstrapping, it will do so when the MA registers with the
        Controller; it may also be told a Group-ID and whether to include the
        MA-ID as well as the Group-ID in its Reports. A Group-ID would be
        shared by several MAs and could be useful for privacy reasons (for
        instance to hinder tracking of a mobile MA device). The MA may also
        tell the Controller its Capabilities (such as the Measurement Methods
        it can perform) (see next sub-section).</t>

        <t>If the device with the MA re-boots, then the MA need to
        re-register, so that it can receive a new Instruction. 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) before re-registering.</t>

        <t>Whilst the LMAP WG considers the bootstrapping process, it is out
        of scope to define a bootstrap mechanism, as it depends on the type of
        device and access.</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 Measurement
        Instructions, which it then acts on autonomously.</t>

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

(Capability request)                   ->
                                       <-        List of Measurement 
                                                      Methods
ACK                                    ->

                                       
Instruction:
[(Measurement Task (parameters)),      ->
 (Measurement Schedule),
 (Report Channel(s))]
                                       <-              ACK 


Suppress                               ->
                                       <-              ACK 
Un-suppress                               ->
                                       <-              ACK 

                                       <-           Failure report:
                                                      [reason]
ACK                                    ->
]]></artwork>
          </figure></t>

        <t>The Instruction contains:<list style="symbols">
            <t>what Measurement Tasks to do: the Measurement Methods could be
            defined by reference to a registry entry, along with any
            parameters that need to be set (such as the address of the
            Measurement Peer) and any Environmental Constraint (such as,
            'delay the measurement task if the end user is active')</t>

            <t>when to do them: the Measurement Schedule details the timings
            of regular measurement tasks, one-off measurement tasks</t>

            <t>how to report the Measurement Results: via Reporting
            Channel(s), each of which defines a target Collector and Report
            Schedule</t>
          </list></t>

        <t>An Instruction could contain one or more of the above elements,
        since the Controller may want the MA to perform several different
        Measurement Tasks (measure UDP latency and download speed), at several
        frequencies (a regular test every hour and a one-off test
        immediately), and report to several Collectors. The different elements
        can be updated independently at different times and regularities, for
        example it is likely that the Measurement Schedule will be updated
        more often than the other elements.</t>

        <t>A new Instruction replaces (rather than adds to) those elements
        that it includes. For example, if the new Instruction includes (only)
        a Measurement Schedule, then that replaces the old Measurement
        Schedule but does not alter the configuration of the Measurement Tasks
        and Report Channels.</t>

        <t>If the Instruction includes several Measurement Tasks, these could
        be scheduled to run at different times or possibly 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>A Measurement Task may create more than one Measurement Result. For
        example, one Result could be reported periodically, whilst another
        could be an alarm that is reported immediately a the measured value of
        a Metric goes below a threshold.</t>

        <t>In general we expect that the Controller knows what Measurement
        Methods the MA supports, such that the Controller can correctly
        instruct the MA. Note that the Control Protocol does not allow
        negotiation (which would add complexity to the MA, Controller and
        Control Protocol for little benefit).</t>

        <t>However, the Control protocol includes a Capabilities detection
        feature, through which the MA can send to the Controller the complete
        list of Measurement Methods that it is capable of. Note that it is not
        intended to indicate dynamic capabilities like the MA's currently
        unused CPU, memory or battery life. The list of Measurement Methods
        could be useful in several circumstances: when the MA first
        communicates with a Controller; when the MA becomes capable of a new
        Measurement Method; when requested by the Controller (for example, if
        the Controller forgets what the MA can do or otherwise wants to
        resynchronize what it knows about the MA).</t>

        <t>The Controller has the ability to send a &ldquo;suppress&rdquo;
        message to MAs. This could be useful if there is some unexpected
        network issue and so the measurement system wants to eliminate
        inessential traffic. As a result, temporarily the MA does not start
        new Active Measurement Tasks, and it may also stop in-progress
        Measurement Tasks, especially ones that are long-running &amp;/or
        create a lot of traffic. See the next section for more information on
        stopping Measurement Tasks. Note that if a Controller wants to
        permanently stop a Measurement Task, it should send a new Measurement
        Schedule, as suppression is intended to temporarily stop Tasks. The
        Controller can send an "un-suppress" message to indicate that the
        temporary problem is solved and Active Measurement Tasks can begin
        again.</t>

        <t>The figure shows that the various messages are acknowledged, which
        means that they have been delivered successfully.</t>

        <t>There is no need for the MA to confirm to the Controller that it
        has understood and acted on the Instruction, since the Controller
        knows the capabilities of the MA. However, the Control Protocol must
        support robust error reporting by the MA, to provide the Controller
        with sufficiently detailed reasons for any failures. These could
        concern either the Measurement Tasks and Schedules, or the Reporting.
        In both cases there are two broad categories of failure. Firstly, the
        MA cannot action the Instruction (for example, it doesn't include a
        parameter that is mandatory for the requested Measurement Method; or
        it is missing details of the target Collector). Secondly, the MA
        cannot execute the Measurement Task or deliver the Report (for
        example, the MA unexpectedly has no spare CPU cycles; or the Collector
        is not responding). Note that it is not considered a failure if a
        Measurement Task (correctly) doesn't start - for example if the MA
        detects cross-traffic; instead this is reported to the Collector in
        the normal manner.</t>

        <t/>

        <t>Finally, note that the MA doesn't do a 'safety check' with the
        Controller (that it should still continue with the requested
        Measurement Tasks) - nor does it inform the Controller about
        Measurement Tasks starting and stopping. It simply carries out the
        Measurement Tasks as instructed, unless it gets an updated
        Instruction.</t>

        <t>The LMAP WG will define a Control Protocol and its associated Data
        Model that implements the Protocol &amp; Information Model. This may
        be a simple instruction - response protocol, and LMAP will specify how
        it operates over an existing protocol - to be selected, perhaps
        REST-style HTTP(s) or NETCONF-YANG.</t>

        <t/>
      </section>

      <section title="Starting and stopping Measurement Tasks">
        <t>The LMAP WG is neutral to what the actual Measurement Task is. The
        WG does not define a generic start and stop process, since the correct
        approach depend on the particular Measurement Task; the details are
        defined as part of each Measurement Method, and hence potentially by
        the IPPM WG.</t>

        <t>Once the MA gets its Measurement and Report Schedules from its
        Controller then it acts autonomously, in terms of operation of the
        Measurement Tasks and reporting of the result. One implication is that
        the MA initiates Measurement Tasks. As an example, for the common case
        where the MA is on a home gateway, the MA initiates a &lsquo;download
        speed test&rsquo; by asking a Measurement Peer to send the file.</t>

        <t/>

        <t>Many Active Measurement Tasks begin with a pre-check before the
        test traffic is sent. Action could include:</t>

        <t><list style="symbols">
            <t>the MA checking that there is no cross-traffic (ie that the
            user isn&rsquo;t already sending traffic);</t>

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

            <t>the first part of the Measurement Task consisting of traffic
            that probes the path to make sure it isn&rsquo;t overloaded.</t>
          </list>It is possible that similar checks continue during the
        Measurement Task, especially one that is long-running &amp;/or creates
        a lot of Test Traffic, which may be abandoned whilst in-progress. A
        Measurement Task could also be abandoned in response to a "suppress"
        message (see previous section). 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.</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, it is
        suggested that the Measurement Schedule includes a time limit ("run
        the 'upload speed' Measurement Task once an hour for the next 30
        days") and that the Measurement Schedule is updated regularly (say,
        every 10 days).</t>
      </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,
        and the context in which they were obtained.</t>

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

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

        <t>The MA acts autonomously in terms of reporting; it simply sends
        Reports as defined by the Controller's Instruction.</t>

        <t>The Report contains:<list style="symbols">
            <t>the MA's identifier, or perhaps 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>
          </list></t>

        <t>The MA may report the Results to more than one Collector, if the
        Instruction says so. It could also report a different subset of
        Results to different Collectors.</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 pre-process Measurement
        Results before it reports them. Potential examples of pre-processing
        by the MA are:</t>

        <t><list style="symbols">
            <t>labelling, or perhaps not including, Measurement Results
            impacted by for instance cross-traffic or the MP being busy</t>

            <t>detailing the start and end of suppression</t>

            <t>filtering outlier Results</t>

            <t>calculating some statistic like average (beyond that defined by
            the Measurement Task itself)</t>
          </list></t>

        <t>The measurement system may define what happens if a Collector
        unexpectedly does not hear from a MA. Possible solutions could include
        the ability for a Collector to 'pull' Measurement Results from a MA,
        or (after an out-of-scope indication from the Collector to the
        Controller) for the Controller to send a fresh Report Schedule to the
        MA. 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>

        <t>The LMAP WG will define a Report Protocol and its associated Data
        Model that implements the Protocol &amp; Information Model. This may
        be a simple instruction - response protocol, and LMAP will specify how
        it operates over an existing protocol - to be selected, perhaps
        REST-style HTTP(s) or IPFIX.</t>

        <t/>
      </section>

      <section title="Items beyond the scope of the LMAP Protocol Model">
        <t>There are several potential interactions between LMAP elements that
        are out of scope of definition by the LMAP WG:</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, probably 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.</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 LMAP
            WG. 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 test traffic of one MA is
                treated by the other MA just like any other user traffic.</t>
              </list></t>

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

        <section title="User-controlled measurement system">
          <t>The WG 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>a 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. Note that a user can&rsquo;t directly initiate a
              Measurement Task on an ISP- (or regulator-) controlled MA.</t>

              <t>a user could deploy their own measurement system, with their
              own MA, Controller and Collector. For example, the user could
              download all three functions onto the same user-owned end
              device; then the LMAP Control and Report protocols do not need
              to be used, but using LMAP's Information Model would still be
              beneficial. The MP could be in the home gateway or outside the
              home network; in the latter case the MP 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 user to initiate the
          Measurement Task(s). The mechanism is out-of-scope of the LMAP WG,
          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 the
          privacy of the Measurement Results and Subscriber information.</t>
        </section>
      </section>
    </section>

    <section title="MA Deployment considerations">
      <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 in a single measurement e.g., if there are multiple
      output interfaces, there might be a Measurement Agent per interface.</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 operator. 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 of the below may also apply.</t>

      <section title="Measurement Agent embedded in site gateway">
        <t>A Measurement Agent embedded with the site gateway (e.g. in the
        case of a 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 and passive measurements
        could easily be performed. Similarly, due to this user traffic
        visibility, an Active Measurements Task could be rescheduled so as not
        to 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, if the site gateway is owned and operated by
        the service provider, the Measurement Agent will generally not be
        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 configuration or firewall pin holing is configured. This
        would require user intervention, and ultimately might not be an option
        available to the user (perhaps due to permissions). The Measurement
        Agent may originate a session towards the Controller and maintain the
        session for bidirectional communications. This would alleviate the
        need to have user intervention on the gateway, but would reduce the
        overall scalability of the Controller as it would have to maintain a
        higher number of active sessions. That said, sending keepalives to
        prop open the firewall could serve a dual purpose in testing network
        reachability for the Measurement Agent. An alternative would be to use
        a protocol such as UPnP or PCP <xref target="RFC6887"/> to control the
        NAT/firewall if the gateway supports this kind of control.</t>

        <t/>
      </section>

      <section title="Measurement Agent in multi homed site">
        <t>A broadband site may be multi-homed. For example, the site may be
        connected to multiple broadband ISPs (perhaps for redundancy or load-
        sharing), or have a broadband as well as mobile/WiFi connectivity. It
        may also be helpful to think of dual stack IPv4 and IPv6 broadband
        sites as multi-homed. In these cases, there needs to be clarity on
        which network connectivity option is being measured. Sometimes this is
        easily resolved by the location of the MA itself. For example, if the
        MA is built into the gateway (and the gateway only has a single WAN
        side interface), there is little confusion or choice. However, for
        multi-homed gateways or devices behind the gateway(s) of multi-homed
        sites it would be preferable to explicitly select the network to
        measure (e.g. <xref target="RFC5533"/>) but the network measured
        should be included in the Measurement Result. 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 (which is
        generally a broadband connected site). 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.). <xref target="RFC6419"/> provides the current
        practices of multi-interfaces hosts today. As some of the end goals of
        a MA is to replicate the end user's network experience, it is
        important to understand the current practices.</t>

        <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.</t>

      <t>We assume that each Measurement Agent will receive measurement tasks
      configuration, scheduling and reporting instructions from a single
      organisation (operator of 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 be
      prevented from replay. If a malicious party can gain control of the
      Measurement Agent they can use the MA capabilities to launch DoS attacks
      at targets, reduce the network user experience and corrupt the
      measurement results that are reported to the Collector. By altering the
      tests that are operated and/or the Collector address 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).</t>

      <t>The reporting of the MA must also be secured to maintain
      confidentiality. The results must be encrypted such that only the
      authorised Collector can decrypt the results to prevent the leakage of
      confidential or private information. In addition it must be
      authenticated that the results have come from the expected MA and that
      they have not been tampered with. It must not be possible to fool a MA
      into injecting falsified data into the measurement platform or to
      corrupt the results of a real MA. The results must also be held and
      processed securely after collection and analysis.</t>

      <t>Availability should also be considered. 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. This potential
      issue is currently handled by a code of conduct. It is outside the scope
      of the LMAP WG to consider the issue.</t>

      <t/>
    </section>

    <section title="Privacy Considerations for LMAP">
      <t>The LMAP Working Group will consider privacy as a core requirement
      and will ensure that by default measurement and collection mechanisms
      and protocols operate in a privacy-sensitive manner, i.e. 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"/>. There are dependencies on the integrity of the LMAP
      security mechanisms, described in the Security Considerations section
      above.</t>

      <t>We begin with a set of assumptions related to protecting the
      sensitive information of individuals and organizations 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 organizations who
        participate in measurement and collection of results.<list
            style="symbols">
            <t>Individual Internet Users: Persons who utilize 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: Organizations who offer Internet
            access service subscriptions, and thus have access to sensitive
            information of Individuals who choose to use the service. These
            organizations desire to protect their subscribers and their own
            sensitive information which may be stored in the process of
            measurement and result collection.</t>

            <t>Other LMAP system Operators: Organizations 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 organizations have sensitive information involved in
        the LMAP system and revealed by measurements, and many of the same
        mitigations are applicable. Further, the ISPs store information on
        their subscribers beyond that used in the LMAP system (e.g., 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 authorized Internet User Sensitive
        Information:</t>

        <t><list style="symbols">
            <t>Sub-IP layer addresses and names (e.g., MAC address, BS 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 (Active)
            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 (e.g., certificates)</t>
          </list></t>

        <t>Other organizations 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="Key Distinction Between Active and Passive Measurement Tasks">
        <t>There are many possible definitions for the two main categories of
        measurement types, active and passive. For the purposes of this memo,
        we describe Passive and Active Measurements as follows:</t>

        <t>Passive: measurements conducted on Internet User traffic, such that
        sensitive information is present and stored in the measurement system
        (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 (e.g., Active Queue Management, Deep Packet Inspection).
        Passive measurements could reveal all websites a subscriber visits and
        the applications and/or services they use.</t>

        <t>Active: measurements conducted on traffic which serves only the
        purpose of measurement. Even if a user host generates active
        measurement traffic, there is significantly limited sensitive
        information about the Subscriber present and stored in the measurement
        system compared to the passive case, as follows:<list style="symbols">
            <t>IP address in use (and possibly Sub-IP addresses and names)</t>

            <t>Status as a study volunteer schedule of active tests</t>
          </list></t>

        <t>On the other hand, the sensitive information for an Internet
        Service Provider is the same whether active or passive measurements
        are used (e.g., measurement results).</t>

        <t>Both Active and Passive measurements 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 have 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 and Registration">
          <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 LMAP 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 Control/Collection
          entities, or simply install new methods of measurement (e.g., a
          passive DNS Query collector). 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 (or Registration) process provides sensitive
          information about the LMAP system and the organization 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 (or Registration process that
          follows), the MA receives its MA-ID which is a persistent pseudonym
          for the subscriber in the case that the MA is located at a service
          demarcation point. Thus, the MA-ID is considered sensitive
          information, because it could provide the link between subscriber
          identification and measurements or observations on traffic.</t>

          <t>Also, the Bootstrap or Registration 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 anonymization 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 themselves. The schedule/timing of
          specific measurements is also sensitive, because an attacker
          intending to bias the results without being detected can use this
          information to great advantage.</t>

          <t>An organization operating the Controller having no service
          relationship with a user who hosts the measurement agent *could*
          gain real-name mapping to 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
          LMAP Measurement Agent and Collector is illustrated in Section 5.4.
          The primary purpose of this exchange is to authenticate and collect
          results from a Measurement Agent, which it has measured autonomously
          and stored.</t>

          <t>Beyond the Controller-MA exchange, the new and highly-sensitive
          information exposed in the Collector-MA exchange is the measurement
          results. Organizations 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="Active Measurement Peer &lt;-&gt; Measurement Agent ">
          <t>Although the specification of the mechanisms for measurement is
          beyond the LMAP scope, the high-level communications model below
          illustrates measurement information and results flowing between
          active measurement devices as a potential privacy issue. The primary
          purpose of this exchange is to execute measurements 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><figure>
              <artwork><![CDATA[ _________________                              _________________
|                 |                            |                 |
|  Meas Peer      |=========== NAT ? ==========|  Meas 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 Tests

Return 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
          packets (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, and this should be avoided when the degradation
          of secure measurement is minimal.</t>
        </section>

        <section title="Passive Measurement Peer &lt;-&gt; Measurement Agent ">
          <t>Although the specification of the mechanisms for measurement is
          beyond the LMAP scope, the high-level communications model below
          illustrates passive monitoring and measurement of information
          flowing between production network devices as a potential privacy
          issue. The primary purpose of this model is to illustrate collection
          of user information of interest with the Measurement Agent
          performing the monitoring and storage of the results. This
          particular exchange is for DNS Response Time, which most frequently
          uses UDP transport.</t>

          <t><figure>
              <artwork><![CDATA[ _________________                              ___________   _____
|                 |                            |           | |     |
|  Meas Peer DNS  |=========== NAT ? ==========| Meas Agent|=|User |
|_________________|                            |___________| |_____|

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

]]></artwork>
            </figure>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 Internet User sensitive information of
          interest (listed above) can be collected and stored in the passive
          monitoring scenario. Thus, the LMAP Collection of passive
          measurements provides the additional sensitive information exposure
          to a Collection-path observer, and this information must be
          secured.</t>
        </section>

        <section title="Result Storage and Reporting">
          <t>Although the mechanisms for communicating results (beyond the
          initial Collector) are beyond the LMAP scope, there are potential
          privacy issues related to a single organization'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".</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."</t>

          <t>All of passive measurement is surveillance, with inherent
          risks.</t>

          <t>Active measurement methods which avoid periods of user
          transmission indirectly produce a record of times when a subscriber
          or authorized user has utilized their Internet access service.</t>

          <t>Active measurements may also utilize and store a subscriber's
          currently assigned IP address when conducting measurements that are
          relevant to a specific subscriber. Since the measurements are
          time-stamped, the measurement results 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 unauthorized 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 results
          storage which serves the Collector function (also applicable to
          temporary storage on the Collector itself). Extensive security and
          privacy threat mitigations are warranted for the storage system.
          Although the scope of its measurement and storage is smaller than
          the collector's, an individual Measurement Agent stores sensitive
          information temporarily, and also needs protections.</t>

          <t>The LMAP Controller may have direct access to storage of Service
          Parameters, Subscriber information (location, billing, etc.), and
          other information which the controlling organization considers
          private, and needs protection in this case.</t>

          <t>The communications between the local storage of the Collector and
          other storage facilities (possibly permanent mass storage), is
          beyond the scope of the LMAP work at this time, though this
          communications channel will certainly need protection as well as the
          mass storage itself.</t>
        </section>

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

          <t>The main risk is that the LMAP system could un-wittingly provide
          a key piece of the correlation chain, starting with an unknown
          Subscriber's IP address and another piece of information (e.g.,
          Subscriber X utilized Internet access from 2000 to 2310 UTC, because
          the active measurements 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 unauthorized utilization 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>The collection and reporting of passive traffic measurements is a
          form of secondary use, and subscribers' permission and measured
          ISP's permission should be obtained before measurement. Although
          user traffic is only indirectly involved, active measurement results
          provide limited information about the subscriber/ISP and may
          constitute secondary use. Use of the measurements in unauthorized
          marketing campaigns would qualify as Secondary Use.</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 Minimization">
          <t>Section 6.1 of <xref target="RFC6973"/> encourages collecting and
          storing the minimal information needed to perform a task.</t>

          <t>There are two levels of information needed for LMAP results to be
          useful for a specific task: Network Operator and User
          troubleshooting, and General results reporting.</t>

          <t>The minimal supporting information for general results is
          conducive to protection of sensitive information, as long as the
          results can be aggregated into large categories (e.g., 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 the results applicable to the desired
          measurement path are provided.. However, this implies a filtering
          process to reduce the information fields allocated to this task,
          because greater detail was needed to conduct the measurements in the
          first place.</t>

          <t>For a Network Operator and User troubleshooting a performance
          issue or failure, potentially all the network information (e.g., 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, and represents a need where the maximum relevant
          information is desirable, therefore the greatest protections should
          be applied.</t>

          <t>We note that a user may give temporary permission for passive
          measurements to enable detailed troubleshooting, but withhold
          permission for passive measurements in general. Here the greatest
          breadth of sensitive information is potentially exposed, and the
          maximum privacy protection must be provided.</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 minimize the data reported, but also to
          balance this desire with the needs of troubleshooting when a service
          subscription exists between the user and organization operating the
          measurements.</t>

          <t>For passive measurements where the MA reports flow information to
          the Collector, the Collector may perform pre-storage minimization
          and other mitigations (below) to help preserve privacy.</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 anonymization of user identifiable data
          applicable to passive measurement have been identified in <xref
          target="RFC6235"/>. However, the findings of several of the same
          authors is that "there is increasing evidence that anonymization
          applied to network trace or flow data on its own is insufficient for
          many data protection applications as in <xref target="Bur10"/>."</t>

          <t>Essentially, the details of passive flow measurements can only be
          accessed by closed organizations, and unknown injection attacks are
          always less expensive than the protections from them. However, some
          forms of summarized passive measurement may protect the user's
          sensitive information sufficiently well, and so each metric must be
          evaluated in the light of privacy.</t>

          <t>The methods in <xref target="RFC6235"/> could be applied more
          successfully in active measurement, 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 anonymized
          results, then fingerprinting those records to ascertain the
          anonymization process.</t>

          <t>Beside anonymization of measured results for a specific user or
          provider, the value of sensitive information can be further diluted
          by summarizing 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 [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 anonymization 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>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) is 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 good practice to time limit the storage of
          personal information.</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 unauthorized access. This is the hand-off
          between privacy and security considerations, found elsewhere in this
          memo. The Data Controller has the (legal) responsibility to maintain
          data protections described in the Subscriber's agreement and
          agreements with other organizations.</t>

          <t>Another standard method for de-personalising data is to blur it
          by adding synthetic data, data-swapping, or perturbing the values in
          ways that can be reversed or corrected.</t>
        </section>
      </section>
    </section>

    <section title="IANA Considerations">
      <t>There are no IANA considerations in this memo.</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 numerous people for much discussion, directly and on the
      LMAP list. This document tries to capture the current conclusions.
      Thanks to Juergen Schoenwaelder for his detailed review of the
      terminology.</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 varous aspects of the privacy section</t>

            <t>updated references</t>

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

  <back>
    <references title="Informative References">
      <reference anchor="Bur10">
        <front>
          <title>The Role of Network Trace Anonymization 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="Q1741">
        <front>
          <title>IMT-2000 references to Release 9 of GSM-evolved UMTS core
          network</title>

          <author fullname="ITU-T Recommendation" initials=""
                  surname="Q.1741.7">
            <!---->

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

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

        <seriesInfo name="" value="http://www.itu.int/rec/T-REC-Q.1741.7/en"/>
      </reference>

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

      <?rfc include='reference.I-D.bagnulo-ippm-new-registry-independent'?>

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

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

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

      <?rfc include='reference.RFC.5533'?>

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

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

      <?rfc include='reference.RFC.6973'?>
    </references>
  </back>
</rfc>
