Network Working Group                                         P. Eardley
Internet-Draft                                                        BT
Intended status: Standards Track                               A. Morton
Expires: April 06, 24, 2014                                        AT&T Labs
                                                              M. Bagnulo
                                                            T. Burbridge
                                                               P. Aitken
                                                               A. Akhter
                                                           Cisco Systems
                                                        October 03, 21, 2013

        A framework for large-scale measurement platforms (LMAP)


   Measuring broadband service on a large scale requires standardisation
   of the logical architecture and a description 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).
   The document is a contribution towards the LMAP working group's

Status of This Memo

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   This Internet-Draft will expire on April 06, 24, 2014.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Outline of an LMAP-based measurement system . . . . . . . . .   7
   4.  Constraints . . . . . . . . . . . . . . . . . . . . . . . . .  10
     4.1.  Measurement system is under the direction of a single
           organisation  . . . . . . . . . . . . . . . . . . . . . .  10  11
     4.2.  Each MA may only have a single Controller at any point in
           time  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   5.  LMAP Protocol Model . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  Bootstrapping process . . . . . . . . . . . . . . . . . .  12
     5.2.  Control Protocol  . . . . . . . . . . . . . . . . . . . .  13  14
     5.3.  Starting and stopping Measurement Tasks . . . . . . . . .  16
     5.4.  Report Protocol . . . . . . . . . . . . . . . . . . . . .  17
     5.5.  Items beyond the scope of the LMAP Protocol Model . . . .  18
       5.5.1.  User-controlled measurement system  . . . . . . . . .  19
   6.  Details of the LMAP framework . . . . . . . . . . . . . . . .  19  20
     6.1.  Measurement Agent (MA)  . . . . . . . . . . . . . . . . .  19  20
       6.1.1.  Measurement Agent embedded in site gateway  . . . . .  20
       6.1.2.  Measurement Agent embedded behind Site NAT /Firewall   20   21
       6.1.3.  Measurement Agent in-line with site gateway . . . . .  21
       6.1.4.  Measurement Agent in multi homed site . . . . . . . .  21  22
     6.2.  Measurement Peer (MP) . . . . . . . . . . . . . . . . . .  22
     6.3.  Controller  . . . . . . . . . . . . . . . . . . . . . . .  22  23
     6.4.  Collector . . . . . . . . . . . . . . . . . . . . . . . .  23
   7.  Security considerations . . . . . . . . . . . . . . . . . . .  23
   8.  Privacy Considerations for LMAP . . . . . . . . . . . . . . .  24
     8.1.  Categories of Entities with Information of Interest . . .  24  25
     8.2.  Examples of Sensitive Information . . . . . . . . . . . .  25
     8.3.  Key Distinction Between Active and Passive Measurement
           Tasks . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     8.4.  Communications Model (for Privacy)  . . . . . . . . . . .  26
       8.4.1.  Controller <-> Measurement Agent  . . . . . . . . . .  26  27
       8.4.2.  Collector <-> Measurement Agent . . . . . . . . . . .  27  28
       8.4.3.  Active Measurement Peer <-> Measurement Agent . . . .  28
       8.4.4.  Passive Measurement Peer <-> Measurement Agent  . . .  29
       8.4.5.  Result Storage and Reporting  . . . . . . . . . . . .  30

     8.5.  Threats . . . . . . . . . . . . . . . . . . . . . . . . .  30
       8.5.1.  Surveillance  . . . . . . . . . . . . . . . . . . . .  30
       8.5.2.  Stored Data Compromise  . . . . . . . . . . . . . . .  30  31
       8.5.3.  Correlation and Identification  . . . . . . . . . . .  31
       8.5.4.  Secondary Use and Disclosure  . . . . . . . . . . . .  31
     8.6.  Mitigations . . . . . . . . . . . . . . . . . . . . . . .  31  32
       8.6.1.  Data Minimization . . . . . . . . . . . . . . . . . .  31  32
       8.6.2.  Anonymity . . . . . . . . . . . . . . . . . . . . . .  33
       8.6.3.  Pseudonymity  . . . . . . . . . . . . . . . . . . . .  33  34
       8.6.4.  Other Mitigations . . . . . . . . . . . . . . . . . .  34
     8.7.  The potential role of a Group-ID for privacy  . . . . . .  34
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34  36
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  34  36
   11. History . . . . . . . . . . . . . . . . . . . . . . . . . . .  34  36
     11.1.  From -00 to -01  . . . . . . . . . . . . . . . . . . . .  37
   12. Informative References  . . . . . . . . . . . . . . . . . . .  34  37
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36  38

1.  Introduction

   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:

   o  Operators: to help plan their network and identify faults

   o  Regulators: to benchmark several network operators and support
      public policy development

   Further details of the use cases can be found at
   [I-D.linsner-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.

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

   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.).

   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: "Measure the 'UDP latency' with the
   Measurement Peer; repeat every hour at xx.05".  The
   Controller also manages a MA by instructing it how to report the
   measurement results, for example: "Report results once a day in a
   batch at 4am".  We refer to these as the Measurement Schedule and
   Report Schedule.

   The Collector accepts Reports from the MAs with the results from
   their measurement tasks.  Therefore the MA is a device that initiates
   the measurement tasks, gets instructions from the Controller and
   reports to the Collector.

   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.

   Over the years various efforts inside and outside the IETF have
   worked on independent components of such a system.  There are also
   existing systems that are deployed today.  However, these are either
   proprietary, closed, and/or not standardized.  The IETF Large-Scale
   Measurement of Broadband Performance (LMAP) Working Group is
   chartered to specify the information model, associated data models,
   and select/extend one or more protocols for secure measurement
   control and measurement result collection.

   The goal is to have the measurements (made using the same metrics and
   mechanisms) for a large number of points on the Internet, and to have
   the results collected and stored in the same form.

   The desirable features for a large-scale measurement systems we are
   designing for are:

   o  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

   o  Large-scale - [I-D.linsner-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

   o  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.

2.  Terminology

   This section defines terminology for LMAP.  Please note that defined
   terms are capitalized.

   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).

   Bootstrap Protocol: A protocol that initialises a Measurement Agent
   with the information necessary to be integrated into a measurement

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

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

   Control Protocol: The protocol delivering Instruction(s) from a
   Controller to a Measurement Agent.  It also delivers logging
   information and capabilities information from the Measurement Agent
   to the Controller.

   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.

   Data Model: The implementation of an Information Model in a
   particular data modelling language.

   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.

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

   Group-ID: An identifier of a group of MAs.

   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.

   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.

   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.

   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.

   Measurement Parameter: A parameter whose value is left open by the
   Measurement Method.

   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.

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

   Measurement Schedule: the schedule for performing a series of
   Measurement Tasks.

   Measurement Suppression: a type of Instruction that stops
   (suppresses) Measurement Tasks.

   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.

   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.

   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).

   Report: The Measurement Results and other associated information (as
   defined by the Instruction); a specific instance of the Data Model.
   The Report is sent by a Measurement Agent to a Collector.

   Report Channel: a specific Report Schedule and Collector

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

   Report Schedule: the schedule for sending a series of Reports to a

   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, to register a user or
   a list of users authorized to enjoy these services, and also to set
   the limits relative to the use that associated users make of these
   services.  (This definition is from [Q1741].)

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

3.  Outline of an LMAP-based measurement system

   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, whilst the subsequent sections study the
   LMAP components in more detail.

   The first component is a Measurement Task, which measures some
   performance or reliability Metric of interest.  An Active Measurement
   Task involves either a Measurement Agent injecting Test Traffic into
   the network destined for a Measurement Peer, 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.

   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 [registry] 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.

   In order for a Measurement Agent and a Measurement Peer to execute an
   Active Measurement Task, they exchange Test Traffic.  The protocols
   used for the Test Traffic is out of the scope of the LMAP WG and
   falls within the scope of the IETF WGs such as IPPM.

   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.

   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.

   The Controller manages a MA by instructing it which tests it should
   perform and when.  For example it may instruct a MA at a home
   gateway: "Run the 'download speed test' with the test server 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".  The Controller
   also manages a MA by instructing it how to report the test results,
   for example: "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".  As well as regular tests, a Controller can initiate a
   one-off test ("Do test now", "Report as soon as possible").  These
   are called the Measurement and Report Schedule.

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

   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.

   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).

   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
   test to diagnose a fault, then it should understand what problem the
   customer is experiencing and what tests have already been run.  The
   Subscribers' service parameters are already gathered and stored by
   existing operations systems.

   A Results Database 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.

   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

   The operator's OAM (Operations, Administration, and Maintenance) uses
   the results from the tools.

               +---------------+   Test     +-------------+   Scope
      +------->| Measurement   |<---------->| Measurement |   v
      |        |   Agent       |   Traffic  |     Peer    |   ^
      |        +---------------+            +-------------+   |
      |              ^      |                                 |
      |  Instruction |      |  Report                         |
      |              |      +-----------------+               |
      |              |                        |               |
      |              |                        v               LMAP
      |         +------------+             +------------+     Scope
      |         | Controller |             |  Collector |     |
      |         +------------+             +------------+     v
      |                ^   ^                       |          ^
      |                |   |                       |          |
      |                |   +----------+            |          |
      |                |              |            v          |
   +-----------+   +---------+    +--------+    +----------+  |
   |Initializer|   |Parameter|--->|Analysis|<---|Repository|  Out
   +-----------+   |DataBase |    | tools  |    +----------+  of
                   +---------+    +--------+                  Scope

   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)

4.  Constraints
   The LMAP framework makes some important assumptions, which constrain
   the scope of the work to be done.

4.1.  Measurement system is under the direction of a single organisation

   In the LMAP framework (as defined in the WG's charter) 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.

   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.

4.2.  Each MA may only have a single Controller at any point in time

   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

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

5.  LMAP Protocol Model

   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:

   1.  What problem is the protocol trying to achieve?

   2.  What messages are being transmitted and what do they mean?

   3.  What are the important, but unobvious, features of the protocol?"

   An LMAP system goes through the following phases:

   o  a bootstrapping process before the MA can take part in the three
      items below

   o  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

   o  the actual Measurement Tasks are performed.  An Active Measurement
      Task involves sending test 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

   o  a Report Protocol, which delivers a Report from the MA to a
      Collector.  The Report contains the Measurement Results.

   In the diagrams the following convention is used:

   o  (optional): indicated by round brackets

   o  [potentially repeated]: indicated by square brackets

   The Protocol Model is closely related to the 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.

5.1.  Bootstrapping process

   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).

                                                        | Measurement  |
                                                        |  Agent       |

   (Initial Controller details:
    address or FQDN,                       ->
    security credentials)

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

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

   Typically the MA is behind a NAT, so needs to initiate
   communications, in order that the Controller can communicate with it.
   The normal NAT interactions are not shown in the figure.

   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 or if the details of the initial Controller are statically
   configured or if the measurement system has specific Controllers for
   different devices types.  When the MA registers with the Controller
   it learns its MA identifier; 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 the list of Measurement
   Methods that its capable of (see next sub-section).

   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.

   Open issue: what happens if a Controller fails, how is the MA is
   homed onto a new one?

5.2.  Control Protocol

   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.

   +-----------------+                                   +-------------+
   |                 |                                   | Measurement |
   |  Controller     |===================================|  Agent      |
   +-----------------+                                   +-------------+

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

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

   Suppress                               ->

                                          <-           Failure report:
   ACK                                    ->

   The Instruction contains:

   o  what measurements 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 test if the end
      user is active')

   o  when to do them: the Measurement Schedule details the timings of
      regular tests, one-off tests

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

   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.

   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).

   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).

   The Controller has the ability to send a "suppress" 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 &/or creates a lot of traffic.  See the
   next section for more information on stopping Measuremet Tasks.

   The figure shows that the various messages are acknowledged, which
   means that they have been delivered successfully.  However, the
   "suppress" message is not acknowledged, since it is likely to be
   broadcast to several /many MAs at a time when the measurement system
   wants to eliminate inessential traffic.  Note also that the MA does
   not inform the Controller about Measurement Tasks starting and

   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.  There are two
   broad categories of failure: the MA cannot action the Instruction
   (for example, it doesn't include a parameter that is mandatory for
   the requested Measurement Method); or the Measurement Task could not
   be executed (for example, the MA unexpectedly has no spare CPU
   cycles).  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 (see Section below).

   Comment: the detailed list of reasons below would be more appropriate
   in the Information Model i-d.

   o  no value for a mandatory parameter

   o  time of test is in past

   o  type wrong, eg string given where expect integer

   o  Schedule refers to a Measurement configuration or Report Channel
      that doesn't exist

   o  MA has crashed

   o  MA doesn't (any longer) understand requested Method

   o  MA has run out of CPU, memory, battery power

   o  Collector has disappeared

   o  MP has disappeared

   Finally, note that the MA doesn't do a 'safety check' with the
   Controller (that it should still continue with the requested
   Measurement Tasks) - it simply carries out the Measurement Tasks as
   instructed, unless it gets an updated Instruction.

   The LMAP WG will define a Control Protocol and its associated Data
   Model that implements the Protocol & 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.

5.3.  Starting and stopping Measurement Tasks

   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.

   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.  Therefore for the common
   case where the MA is on a home gateway, the MA initiates a 'download
   speed test' by asking a Measurement Peer to send the file.

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

   o  the MA checking that there is no cross-traffic (ie that the user
      isn't already sending traffic);

   o  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);

   o  the first part of the Measurement Task consisting of traffic that
      probes the path to make sure it isn't overloaded.

   It is possible that similar checks continue during the Measurement
   Task, especially one that is long-running &/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:

   o  For 'upload' tests, the MA not sending traffic

   o  For 'download' tests, the MA closing the TCP connection or sending
      a TWAMP Stop control message.

   Comment: presumably Passive Measurement Tasks don't do pre-checking
   or stopping?

5.4.  Report Protocol

   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.

   +-----------------+                                   +-------------+
   |                 |                                   | Measurement |
   |  Controller   Collector     |===================================|  Agent      |
   +-----------------+                                   +-------------+

                                          <-       Report:
                                                   [MA-ID &/or Group-ID,
                                                    Measurement Results,
                                                       Measurement Task]
   ACK                                    ->

   The MA acts autonomously in terms of reporting; it simply sends
   Reports as defined by the Controller's Instruction.

   The Report contains:

   o  the MA's identifier, or perhaps a Group-ID to anonymise results

   o  the actual Measurement Results, including the time they were

   o  the details of the Measurement Task (to avoid the Collector having
      to ask the Controller for this information later)

   Depending on the requirements of the measurement system, the MA might
   label, or perhaps not include, Measurement Results impacted by for
   instance cross-traffic or the MP being busy.  If applicable the
   Measurement Report includes the start and end of suppression.

   The MA may report the results to more than one Collector, if the
   Instruction says so.  It could report a different subset of Results
   to different Collectors.

   The LMAP WG will define a Report Protocol and its associated Data
   Model that implements the Protocol & 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.

5.5.  Items beyond the scope of the LMAP Protocol Model

   There are several potential interactions between LMAP elements that
   are out of scope of definition by the LMAP WG:

   1.  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

   2.  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.

   3.  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.

       *  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.

   4.  It does not specifically define a user-initiated measurement
       system, see sub-section.

5.5.1.  User-controlled measurement system

   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):

   1.  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't directly initiate a Measurement
       Task on an ISP- (or regulator-) controlled MA.

   2.  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

   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.

6.  Details of the LMAP framework

   This section contains a more detailed discussion of the four
   components of the LMAP framework.

6.1.  Measurement Agent (MA)

   The Measurement Agent is the component that is responsible for
   executing the Measurement Tasks.  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.  The Measurement Agent's
   configuration (specifically which Controller to initially connect
   to), is out of scope within LMAP.  However, depending on the type of
   probe, it could be manually configured by the user, pre-configured
   before shipment to the end user, or configured by the application (in
   the case of some PC based Measurement Agents).  For example, a
   Measurement Agent that is included in the app for a content provider
   might be configured automatically by the content provider to use the
   content provider's LMAP Controller.  That said, there should be an
   element of local premises configuration that allows the Measurement
   Agent (especially in the case of Active Measurements Tasks) to mimic
   performance of user applications at the same site.  For example,
   making use of the same DNS server as the remainder of the site.  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.

6.1.1.  Measurement Agent embedded in site gateway
   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.

6.1.2.  Measurement Agent embedded behind Site NAT /Firewall

   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
   [RFC6887] to control the NAT/firewall if the gateway supports this
   kind of control.

6.1.3.  Measurement Agent in-line with site gateway
   As mentioned earlier, there are benefits in the Measurement Agent's
   ability to observe the site's user traffic.  It allows the
   Measurement Agent to back off a potentially disruptive Active
   Measurements Task to avoid impacting the user.  A Passive
   Measurements Task allows the Measurement Agent to gather data without
   the overhead of Test Traffic (of interest to both the site user and
   network operator) as well as potentially provide a greater number of
   samples.  A Measurement Agent behind the gateway would generally not
   be privy to observation of the user traffic unless the Measurement
   Agent was placed in-line with the site gateway or the site gateway
   traffic was replicated to the Measurement Agent (a capability
   generally not found in home broadband gateways).

6.1.4.  Measurement Agent in multi homed site

   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. [RFC5533]) but the network measured should be
   included in the Measurement Result.  Section 3.2 of [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.

6.2.  Measurement Peer (MP)
   A Measurement Peer is the other side of an Active Measurements Task -
   the target of Test Traffic from a Measurement Agent.  The Measurement
   Peer could also take many different forms: a web site, a service
   (VoIP), a DNS server, an application specific server (e.g., webex), a
   well known web site (e.g., youtube, google search), even another
   Measurement Agent in another home could perform as a Measurement Peer
   for a given Measurement Task.  Particularly useful could be a MP that
   is well placed bandwidth-wise and can handle thousand of sessions of
   Test Traffic.

6.3.  Controller

   A Controller is responsible for providing the Measurement Agent with
   instructions which include the Measurement Schedule, parameters, etc.
   It is basically the entity controlling the Measurement Agents in a
   LMAP domain.

   For scaling purposes there may be several Controllers, perhaps
   regionally located.  A large scale test making use of multiple
   Controllers would need a master Controller that is the ultimate
   source of direction.

6.4.  Collector

   A Collector is responsible for receiving the Measurement Results from
   the Measurement Agent at the end of a Measurement Task.  It may have
   additional features such as aggregating the results across multiple
   Measurement Agents, remove outliers, create additional statistics,
   (depending on usage of data) anonymization of results for privacy
   reasons (if not done already in the Measurement Agents) etc.  The
   work of anonymization of user identifiable data has been addressed
   for IPFIX via RFC6235 [RFC6235].  For scaling purposes there may be
   several Collectors, perhaps regionally located.  A large scale test
   making use of multiple Collectors would need to aggregate/consolidate
   their results for the complete picture.

7.  Security considerations

   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.

   We assume that each Measurement Agent will receive test
   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).

   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.

   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.

   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.

8.  Privacy Considerations for LMAP

   Comment: It may be better to create a separate draft about 'LMAP
   threats and considerations' containing this section and perhaps the
   security section.

   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.

   This section provides a set of privacy considerations for LMAP.  This
   section benefits greatly from the timely publication of [RFC6973].
   There are dependencies on the integrity of the LMAP security
   mechanisms, described in the Security Considerations section above.

   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.

8.1.  Categories of Entities with Information of Interest

   LMAP protocols need to protect the sensitive information of the
   following entities, including individuals and organizations who
   participate in measurement and collection of results.

   o  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.

   o  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.

   o  Other LMAP system Operators: Organizations who operate measurement
      systems or participate in measurements in some way.

8.2.  Examples of Sensitive Information

   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.

   Examples of Subscriber or authorized Internet User Sensitive

   o  IP address in use

   o  Personal Identification (Real Name)

   o  Location (street address, city)

   o  Subscribed Service Parameters

   o  Contents of Traffic (Activity, DNS queries, Destinations,
      Equipment types, Account info for other services, etc.)

   o  Status as a study volunteer and Schedule of (Active) Measurement

   Examples of Internet Service Provider Sensitive Information:

   o  Measurement Device Identification (Equipment ID and IP address)

   o  Measurement Instructions (choice of measurements)

   o  Measurement Results (some may be shared, others may be private)

   o  Measurement Schedule (exact times)

   o  Network Topology (Locations, Connectivity, Redundancy)

   o  Subscriber billing information, and any of the above Subscriber
      Information known to the provider.

   o  Authentication credentials (e.g., certificates)

   Other organizations will have some combination of the lists above.

8.3.  Key Distinction Between Active and Passive Measurement Tasks

   For the purposes of this memo, we define Passive and Active
   Measurements Tasks as follows:

   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).

   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 present and stored in the measurement system compared to
   the passive case, as follows:

   o  IP address in use

   o  Status as a study volunteer and schedule of active tests

   On the other hand, the sensitive information for an Internet Service
   Provider is the same whether active or passive measurements are used.

8.4.  Communications Model (for Privacy)

   This section briefly presents a set of communication models for LMAP.
   We assume that the Measurement Agent is located behind a NAT/
   Firewall, so it performs the role of Initiator for all

   From a privacy perspective, all LMAP entities can be considered
   "observers" according to the definition in [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.  We note this in the figures below by
   identifying the possible presence of a NAT, which has additional
   significance to the protocols and direction of initiation.

8.4.1.  Controller <-> Measurement Agent

   The high-level communication model for interactions between the LMAP
   Controller and Measurement Agent is illustrated below.  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.

   _________________                              _________________
   |                 |                            |                 |
   |  Controller     |=========== NAT ? ==========|  Meas Agent     |
   |_________________|                            |_________________|

                                  <-              Key Negotiation &
                                                  Encryption Setup
   Encrypted Channel              ->
   Request Capabilities           ->
   Equipment ID & Status
                                  <-              Reply Equipment ID
                                                  Capabil. & Status
   Measurement                    ->
   (MP IP Addrs, set of
    Metrics, Schedule)
                                  <-              ACK (new Status)

   Primarily IP addresses and pseudonyms are exchanged first, then
   measurement-related information of interest such as the metrics,
   schedule, and IP addresses of measurement devices.

   An organization operating the controller having no service
   relationship with the user who hosts the measurement agent *could*
   gain real-name mapping to public IP address through user
   participation in an LMAP system.

8.4.2.  Collector <-> Measurement Agent

   The high-level communication model for interactions between the LMAP
   Measurement Agent and Collector is illustrated below.  The primary
   purpose of this exchange is to authenticate and collect results from
   a Measurement Agent, which it has measured autonomously and stored.

    _________________                              _________________
   |                 |                            |                 |
   |  Collector      |=========== NAT ? ==========|  Meas Agent     |
   |_________________|                            |_________________|

                                  <-              Key Negotiation &
                                                  Encryption Setup
   Encrypted Channel              ->
   Request Capabilities?          ->
   Equipment ID & Status
                                  <-              Reply Equipment ID
                                                  Capabil. & Status
                                  <-              Measurement Results
                                                  (MP IP Addrs, set of
                                                  Metrics, Values)
   ACK                            ->

   Primarily IP addresses and pseudonyms are exchanged first, then
   measurement-related information of interest such as the metrics,
   schedule, results, and IP addresses of measurement devices.

   An organization operating the collector having no service
   relationship with the user who hosts the measurement agent *could*
   gain real-name mapping to public IP address through user
   participation in an LMAP system.

8.4.3.  Active Measurement Peer <-> Measurement Agent

   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

    _________________                              _________________
   |                 |                            |                 |
   |  Meas Peer      |=========== NAT ? ==========|  Meas Agent     |
   |_________________|                            |_________________|
                                  <-              Key Negotiation &
                                                  Encryption Setup
   Encrypted Channel              ->
   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

   This exchange primarily exposes the IP addresses of measurement
   devices and the inference of measurement participation from such
   traffic.  There may be information on key points in a service
   provider's network.  There may also be access to measurement-related
   information of interest such as the metrics, schedule, and results.

   If the measurement traffic is unencrypted, as found in many systems
   today, then both timing and limited results are open to observers.

8.4.4.  Passive Measurement Peer <-> Measurement Agent

   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.

    _________________                              ___________   _____
   |                 |                            |           | |     |
   |  Meas Peer DNS  |=========== NAT ? ==========| Meas Agent|=|User |
   |_________________|                            |___________| |_____|
                                  <-              Name Resolution Req
                                                 (MA+MP IPAddrs,
                                                  Desired Domain Name)
   Return Record                  ->

   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.

   In principle, any of the Internet User information of interest
   (listed above) can be collected and stored in the passive monitoring

8.4.5.  Result Storage and Reporting

   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.

8.5.  Threats

   This section indicates how each of the threats described in [RFC6973]
   apply to the LMAP entities and their communication and storage of
   "information of interest".

8.5.1.  Surveillance

   Section 5.1.1 of [RFC6973] describes Surveillance as the "observation
   or monitoring of and individual's communications or activities."

   All of passive measurement is surveillance, with inherent risks.

   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.

   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.

   Either of the above pieces of information could be useful in
   correlation and identification, described below.

8.5.2.  Stored Data Compromise

   Section 5.1.2 of [RFC6973] describes Stored Data Compromise as
   resulting from inadequate measures to secure stored data from
   unauthorized or inappropriate access.

   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.

   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.

   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.

8.5.3.  Correlation and Identification

   Sections 5.2.1 and 5.2.2 of [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.

   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 at 2300 UTC).

8.5.4.  Secondary Use and Disclosure

   Sections 5.2.3 and 5.2.4 of [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.

   The collection and reporting of passive traffic measurements is a
   form of secondary use, and subscribers' permission should be obtained
   before measurement.  Although user traffic is only indirectly
   involved, active measurement results provide limited information
   about the subscriber and may constitute secondary use.

8.6.  Mitigations

   This section examines the mitigations listed in section 6 of
   [RFC6973] and their applicability to LMAP systems.  Note that each
   section in [RFC6973] identifies the threat categories that each
   technique mitigates.

8.6.1.  Data Minimization

   Section 6.1 of [RFC6973] encourages collecting and storing the
   minimal information needed to perform a task.

   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.

   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.

   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.

   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.

   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

   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.

8.6.2.  Anonymity

   Section 6.1.1 of [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

   Experimental Methods for anonymization of user identifiable data
   applicable to passive measurement have been identified in [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 [Bur10]."

   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.

   The methods in [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 [RFC6973]) for inclusion with the
   shared and anonymized results, then fingerprinting those records to
   ascertain the anonymization process.

   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 [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".

8.6.3.  Pseudonymity

   Section 6.1.2 of [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.

   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.

8.6.4.  Other Mitigations

   Sections 6.2 and 6.3 of [RFC6973] describe User Participation and
   Security, respectively.

   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.

   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.

9.  IANA Considerations

   There are no IANA considerations in this memo.

10.  Acknowledgments

   This document is a merger

8.7.  The potential role of three individual drafts: draft-eardley-
   lmap-terminology-02, draft-akhter-lmap-framework-00, and draft-

   Thanks to numerous people a Group-ID for much discussion, directly and on privacy

   A group identifier may be useful to help maintain privacy.  Several
   MAs would share the
   LMAP list. same Group-ID.  This document tries has been suggested where the
   endusers are sensitive about privacy, for example mobile users do not
   want their location tracked.  Some possibilities are discussed below.

   A Group-ID might be used when Results are forwarded by a Collector to capture
   a third party.  The measurement system operates using MA-IDs, however
   if Results are sent to a third party then Results from several MAs
   are aggregated together, in order to prevent the current conclusions.
   Thanks third party tracking
   them to Juergen Schoenwaelder an individual MA or enduser.

   A Group-ID could be used for his detailed review of the

   Philip Eardley, Trevor Burbridge and Marcelo Bagnulo work in part on Reporting.  The Controller's Instruction
   still refers to an MA using its MA-ID, but Results are reported to
   the Leone research project, Collector including a Group-ID but not an MA-ID.  This might be
   useful where the measurement system is not run by the ISP (in the
   mobile example, the user clearly wants the operator track their
   location).  The Group-ID needs to be sensible, for example MAs with
   the same broadband product (it is not sensible to aggregate Results
   from MAs on 2Mb/s and 300Mb/s lines).  Note that:

   o  A malicious MA could bias overall results by reporting more or
      less often than it is supposed to.  The use of a Group-ID makes
      this harder for a Collector to detect.

   o  An attacker is more likely to be able to break the MA-Collector
      communications, since it can only be secured at the group level,
      for instance with a shared password.  The attacker could then
      report false Results.  Securing at the individual MA level
      intrinsically reveals the MA's identity

   o  A malicious Collector can probably use other information to
      deaggregate the Results per MA, for example by tracking its IP
      address or analysing some per-MA 'fingerprint' information
      associated with the MA-Collector transmission protocol

   o  A conspiratorial Controller could create a per-MA fingerprint (for
      example a unique set of parameters for the Measurement Tasks or
      simply a regular time at which the MA reports), which the
      Collector uses to identify the MA

   o  A well-behaved Collector ensures that it only stores the Group-ID
      and throws away per-MA information.  Then it cannot subsequently
      disaggregate Results per MA - such a breakdown might be requested
      by a government agency, an attacker or even by the measurement
      system itself (say after a change of company policy).  In this
      case, the MA-Collector communication can be secured per MA,
      providing authentication is changed regularly and/or cannot be
      linked to the repository with the Measurement Results.  In
      principle the scenario doesn't need a Group-ID to be defined for
      the Report Protocol - since the Collector can implement the Group-
      ID locally, after Results are reported.

   A Group-ID could be used for Control as well as Reporting.  The same
   Instruction is broadcast to all MAs, which check that they have a
   matching group-id before carrying out the Instruction.  Notes:

   o  The first three bullets above still apply
   o  In addition, the Controller-MA communication is now also less

   o  All the MAs with the same Group-ID probably need to be able to run
      exactly the same set of Measurement Methods.

   o  At least at first glance, failure handling is harder.  It is much
      less useful for the MA to inform the Controller that it cannot
      understand or execute an Instruction - the Controller simply knows
      that one or more MAs, with a particular Group-ID, cannot
      understand or execute the Instruction.  There also seems no point
      an MA reporting the Measurement Methods that it understands (which
      is intended to help a Controller that has forgotten an MA's
      capabilities, perhaps after a crash)

   Conclusion - this topic needs more discussion.  The use of per-MA
   authentication for security seems in tension with the use of Group-
   IDs for privacy.

9.  IANA Considerations

   There are no IANA considerations in this memo.

10.  Acknowledgments

   This document is a merger of three individual drafts: draft-eardley-
   lmap-terminology-02, draft-akhter-lmap-framework-00, and draft-

   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

   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.

11.  History

   First WG version, copy of draft-folks-lmap-framework-00.

11.1.  From -00 to -01

   o  new sub-section of possible use of Group-IDs for privacy

   o  tweak to definition of Control protocol

   o  fix typo in figure in S5.4

12.  Informative References

              Linsner, M., Eardley, P., and T. Burbridge, "Large-Scale
              Broadband Measurement Use Cases", draft-linsner-lmap-use-
              cases-04 (work in progress), October 2013.

              , "A YANG Data Model for LMAP Measurement Agents", ,

              , "Considerations on using NETCONF with LMAP Measurement
              Agents", ,

              , "An LMAP application for IPFIX", ,

              , , , , , "A registry for commonly used metrics.
              Independent registries", , <

   [RFC6241]  , , , , "Network Configuration Protocol (NETCONF)", ,

              , "YANG-API Protocol", ,

              , , , "Large-Scale Measurement of Broadband Performance:
              Use Cases, Architecture and Protocol Requirements", ,

              Burbridge, T., Eardley, P., Bagnulo, M., and J.
              Schoenwaelder, "Information Model for Large-Scale
              Measurement Platforms (LMAP)", , <

   [Bur10]    Burkhart, M., Schatzmann, D., Trammell, B., and E. Boschi,
              "The Role of Network Trace Anonymization Under Attack",
              January 2010.

   [Q1741]    Q.1741.7, ., "IMT-2000 references to Release 9 of GSM-
              evolved UMTS core network",
    , November 2011.

              Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
              A. Morton, "A registry for commonly used metrics.
              Independent registries", draft-bagnulo-ippm-new-registry-
              independent-01 (work in progress), July 2013.

   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330, May

              Mathis, M. and A. Morton, "Model Based Internet
              Performance Metrics", draft-mathis-ippm-model-based-
              metrics-01 (work in progress), February 2013.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, September 1999.

              Burbridge, T., Eardley, P., Bagnulo, M., and J.
              Schoenwaelder, "Information Model for Large-Scale
              Measurement Platforms (LMAP)", draft-burbridge-lmap-
              information-model-00 (work in progress), July 2013.

   [RFC6235]  Boschi, E. and B. Trammell, "IP Flow Anonymization
              Support", RFC 6235, May 2011.

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973, July

Authors' Addresses
   Philip Eardley
   British Telecom
   Adastral Park, Martlesham Heath


   Al Morton
   AT&T Labs
   200 Laurel Avenue South
   Middletown, NJ


   Marcelo Bagnulo
   Universidad Carlos III de Madrid
   Av. Universidad 30
   Leganes, Madrid  28911

   Phone: 34 91 6249500

   Trevor Burbridge
   British Telecom
   Adastral Park, Martlesham Heath


   Paul Aitken
   Cisco Systems, Inc.
   96 Commercial Street
   Edinburgh, Scotland  EH6 6LX

   Aamer Akhter
   Cisco Systems, Inc.
   7025 Kit Creek Road
   RTP, NC  27709