A framework for large-scale measurement
platforms (LMAP)BTAdastral Park, Martlesham HeathIpswichENGLANDphilip.eardley@bt.comAT&T Labs200 Laurel Avenue SouthMiddletown, NJUSAacmorton@att.comUniversidad Carlos III de
MadridAv. Universidad 30LeganesMadrid28911SPAIN34 91 6249500marcelo@it.uc3m.eshttp://www.it.uc3m.esBTAdastral Park, Martlesham HeathIpswichENGLANDtrevor.burbridge@bt.comCisco Systems, Inc.96 Commercial StreetEdinburghScotlandEH6 6LXUKpaitken@cisco.comCisco Systems, Inc.7025 Kit Creek RoadRTPNC27709USAaakhter@cisco.comMeasuring 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).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 100,000 devices. Measurement devices may
also be embedded on a device that is part of an ISP's network, such as a
DSLAM, router, Carrier Grade NAT or ISP Gateway. Such a scale presents
unique problems in coordination, execution and measurement result
collection. Several use cases have been proposed for large-scale
measurements including:Operators: to help plan their network and identify faultsRegulators: to benchmark several network operators and support
public policy developmentFurther details of the use cases can be found in . The LMAP framework should be useful
for these, as well as other use cases, such as to help end users run
diagnostic checks like a network speed test.The LMAP Framework has three basic elements: Measurement Agents,
Controllers and Collectors.Measurement Agents (MAs) initiate the actual measurements, which are
called Measurement Tasks in the LMAP terminology. In principle, there
are no restrictions on the type of device in which the MA function
resides.The Controller instructs one or more MAs and communicates the set of
Measurement Tasks an MA should perform and when. For example it may
instruct a MA at a home gateway: “Measure the ‘UDP
latency’ with www.example.org; 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 gets
Instructions from the Controller, initiates the Measurement Tasks, and
reports to the Collector. The communications between these three LMAP
functions are structured according to a Control Protocol and a Report
Protocol.The desirable features for a large-scale measurement systems we are
designing for are:Standardised - in terms of the Measurement Tasks that they
perform, the components, the data models and protocols for
transferring information between the components. Amongst other
things, standardisation enables meaningful comparisons of
measurements made of the same metric at different times and places,
and provides the operator of a measurement system with a criteria
for evaluation of the different solutions that can be used for
various purposes including buying decisions (such as buying the
various components from different vendors). Today's systems are
proprietary in some or all of these aspects.Large-scale - envisages
Measurement Agents in every home gateway and edge device such as
set-top-boxes and tablet computers, and located throughout the
Internet as well . It is
expected that a measurement system could easily encompass a few
hundred thousand or even millions of Measurement Agents. Existing
systems have up to a few thousand MAs (without judging how much
further they could scale).Diversity - a measurement system should handle different types of
Measurement Agents - for example Measurement Agents may come from
different vendors, be in wired and wireless networks, be able to
execute different sorts of Measurement Task and be on devices with
IPv4 or IPv6 addresses.Figure 1 shows the main components of a measurement system, and the
interactions of those components. Some of the components are outside the
scope of initial LMAP work. In this section we provide an overview of
the whole measurement system and we introduce the main terms needed for
the LMAP framework. The new terms are capitalised. In the next section
we provide a terminology section with a compilation of all the LMAP
terms and their definition. Section 4 onwards considers the LMAP
components in more detail.Other LMAP specifications will define an information model, the
associated data models, and select/extend one or more protocols for the
secure communication: firstly, a Control Protocol, from a Controller to
instruct Measurement Agents what performance metrics to measure, when to
measure them, how/when to report the measurement results to a Collector;
secondly, a Report Protocol, for a Measurement Agent to report the
results to the Collector.The MA performs Measurement Tasks. The MAs are pieces of code that
can be executed in specialised hardware (hardware probe) or on a
general-purpose device (like a PC or mobile phone). The MA may generate
Measurement Traffic and measure some metric associated with its
transfer, or the MA may observe existing traffic, or there may be some
kind of hybrid of these two possibilities. A device with a Measurement
Agent may have multiple interfaces (WiFi, Ethernet, DSL, fibre; and
non-physical interfaces such as PPPoE or IPsec) and the Measurement
Tasks may specify any one of these.The Controller manages a MA through use of the Control Protocol,
which transfer the Instruction to the MA. This describes the Measurement
Tasks the MA should perform and when. For example the Controller may
instruct a MA at a home gateway: “Count the number of TCP SYN
packets observed in a 1 minute interval; repeat every hour at xx.05 +
Unif[0,180] seconds”. The Measurement Schedule determines when the
Measurement Tasks are executed. The Controller also manages a MA by
instructing it how to report the Measurement Results, for example:
“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”. The Report Schedule determines when the Reports are
uploaded to the Collector. The Measurement Schedule and Report Schedule
can define one-off (non-recurring) actions ("Do measurement now",
"Report as soon as possible"), as well as recurring ones.The Collector accepts a Report from a MA with the Measurement Results
from its Measurement Tasks. It then provides the Results to a repository
(see below).A Measurement Method defines how to measure a Metric of interest. It
is very useful to standardise Measurement Methods, so that it is
meaningful to compare measurements of the same Metric made at different
times and places. It is also useful to define a registry for
commonly-used Metrics so that a Metric with its
associated Measurement Method can be referred to simply by its
identifier in the registry. The Measurement Methods and registry will
hopefully be referenced by other standards organisations.Broadly speaking there are two types of Measurement Method. It may
involve a single MA simply observing existing traffic - for example, the
Measurement Agent could count bytes or calculate the average loss for a
particular flow. On the other hand, a Measurement Method may involve
multiple network entities, which perform different roles. For example, a
"ping" Measurement Method, to measure the round trip delay , would
consist of an MA sending an ICMP ECHO request to a responder in the
Internet. In LMAP terms, the responder is termed a Measurement Peer
(MP), meaning that it helps the MA but is not managed by the Controller.
Other Measurement Methods involve a second MA, with the Controller
instructing the MAs in a coordinated manner. Traffic generated
specifically as part of the Measurement Method is termed Measurement
Traffic; in the ping example, it is the ICMP ECHO Requests and Replies.
The protocols used for the Measurement Traffic are out of the scope of
initial LMAP work, and fall within the scope of other IETF WGs such as
IPPM. The Appendix has some other examples of possible arrangements of
Measurement Agents and Peers.A Measurement Task is the action performed by a particular MA at a
particular time, as the specific instance of its role in a Measurement
Method. LMAP is mainly concerned with Measurement Tasks, for instance in
terms of its Information Model and Protocols.For Measurement Results to be truly comparable, as might be required
by a regulator, not only do the same Measurement Methods need to be used
to assess Metrics, but also the set of Measurement Tasks should follow a
similar Measurement Schedule and be of similar number. The details of
such a characterisation plan are beyond the scope of work in IETF
although certainly facilitated by IETF's work.Messages are transferred over a secure Channel. A Control Channel is
between the Controller and a MA; the Control Protocol delivers
Instruction Messages to the MA and Capabilities, Failure and Logging
Information in the reverse direction. A Report Channel is between a MA
and Collector, and the Report Protocol delivers Reports to the
Collector.Finally we introduce several components that are outside the scope of
initial LMAP work and will be provided through existing protocols or
applications. They affect how the measurement system uses the
Measurement Results and how it decides what set of Measurement Tasks to
perform.The MA needs to be bootstrapped with initial details about its
Controller, including authentication credentials. The LMAP work
considers the bootstrap process, since it affects the Information Model.
However, LMAP does not define a bootstrap protocol, since it is likely
to be technology specific and could be defined by the Broadband Forum,
CableLabs or IEEE depending on the device. Possible protocols are SNMP,
NETCONF or (for Home Gateways) CPE WAN Management Protocol (CWMP) from
the Auto Configuration Server (ACS) (as specified in TR-069 ).A Subscriber parameter database contains information about the line,
such as the customer's broadband contract (perhaps 2, 40 or 80Mb/s), the
line technology (DSL or fibre), the time zone where the MA is located,
and the type of home gateway and MA. These parameters are already
gathered and stored by existing operations systems. They may affect the
choice of what Measurement Tasks to run and how to interpret the
Measurement Results. For example, a download test suitable for a line
with an 80Mb/s contract may overwhelm a 2Mb/s line.A results repository records all Measurement Results in an equivalent
form, for example an SQL database, so that they can easily be accessed
by the data analysis tools.The data analysis tools receive the results from the Collector or via
the Results repository. They might visualise the data or identify which
component or link is likely to be the cause of a fault or degradation.
This information could help the Controller decide what follow-up
Measurement Task to perform in order to diagnose a fault. The data
analysis tools also need to understand the Subscriber's service
information, for example the broadband contract.This section defines terminology for LMAP. Please note that defined
terms are capitalized.Bootstrap: A process that integrates a Measurement Agent into a
measurement system.Capabilities: Information about the performance measurement
capabilities of the MA, in particular the Measurement Method roles and
measurement protocol roles that it can perform, and the device hosting
the MA, for example its interface type and speed, but not dynamic
information.Channel: A bi-directional logical connection that is defined by a
specific Controller and MA, or Collector and MA, plus associated
security.Collector: A function that receives a Report from a Measurement
Agent.Controller: A function that provides a Measurement Agent with its
Instruction.Control Channel: a Channel between a Controller and a MA over which
Instruction Messages and Capabilities, Failure and Logging Information
are sent.Control Protocol: The protocol delivering Instruction(s) from a
Controller to a Measurement Agent. It also delivers Capabilities,
Failure and Logging Information from the Measurement Agent to the
Controller.Cycle-ID: A tag that is sent by the Controller in an Instruction and
echoed by the MA in its Report. The same Cycle-ID is used by several MAs
that use the same Measurement Method for a Metric with the same Input
Parameters. Hence the Cycle-ID allows the Collector to easily identify
Measurement Results that should be comparable.Data Model: The implementation of an Information Model in a
particular data modelling language .Environmental Constraint: A parameter that is measured as part of the
Measurement Task, its value determining whether the rest of the
Measurement Task proceeds.Failure Information: Information about the MA's failure to action or
execute an Instruction, whether concerning Measurement Tasks or
Reporting.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 .Input Parameter: A parameter whose value is left open by the Metric
and its Measurement Method and is set to a specific value in a
Measurement Task. Altering the value of an Input Parameter does not
change the fundamental nature of the Measurement Task.Instruction: The description of Measurement Tasks for a MA to perform
and the details of the Report for it to send. It is the collective
description of the Measurement Task configurations, the configuration of
the Measurement Schedules, the configuration of the Report Channel(s),
the configuration of Report Schedule(s), and the details of any
suppression.Instruction Message: The message that carries an Instruction from a
Controller to a Measurement Agent.Logging Information: Information about the operation of the
Measurement Agent and which may be useful for debugging.Measurement Agent (MA): The function that receives Instruction
Messages from a Controller and operates the Instruction by executing
Measurement Tasks (using protocols outside the initial LMAP work scope
and perhaps in concert with one or more other Measurement Agents or
Measurement Peers) and (if part of the Instruction) by reporting
Measurement Results to a Collector or Collectors.Measurement Agent Identifier (MA-ID): a UUID
that identifies a particular MA and is configured as part of the
Bootstrapping process.Measurement Method: The process for assessing the value of a Metric;
the process of measuring some performance or reliability parameter
associated with the transfer of traffic; where this process involves
multiple MAs or MPs, each may perform different roles.Measurement Peer (MP): The function that assists a Measurement Agent
with Measurement Tasks and does not have an interface to the Controller
or Collector.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 Measurement
Tasks.Measurement Task: The action performed by a particular Measurement
Agent that consists of the single assessment of a Metric through
operation of a Measurement Method role at a particular time, with all of
the role's Input Parameters set to specific values.Measurement Traffic: the packet(s) generated by some types of
Measurement Method that involve measuring some parameter associated with
the transfer of the packet(s).Metric: The quantity related to the performance and reliability of
the network that we'd like to know the value of, and that is carefully
specified.Report: The set of Measurement Results and other associated
information (as defined by the Instruction). The Report is sent by a
Measurement Agent to a Collector.Report Channel: a communications channel between a MA and a
Collector, which is defined by a specific MA, Collector, Report Schedule
and associated security, and over which Reports are sent.Report Protocol: The protocol delivering Report(s) from a Measurement
Agent to a Collector.Report Schedule: the schedule for sending Reports to a Collector.Subscriber: An entity (associated with one or more users) that is
engaged in a subscription with a service provider.Suppression: the temporary cessation of Measurement Tasks.The LMAP framework makes some important assumptions, which constrain
the scope of the initial LMAP work.In the LMAP framework, the measurement system is under the
direction of a single organisation that is responsible for any impact
that its measurements have on a user's quality of experience and
privacy. Clear responsibility is critical given that a misbehaving
large-scale measurement system could potentially harm user experience,
user privacy and network security.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.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).An operator may have several Controllers, perhaps with a Controller
for different types of MA (home gateways, tablets) or location
(Ipswich, Edinburgh).A protocol model presents an architectural
model for how the protocol operates and needs to answer three basic
questions:What problem is the protocol trying to achieve?What messages are being transmitted and what do they mean?What are the important, but unobvious, features of the
protocol?An LMAP system goes through the following phases:a bootstrapping process before the MA can take part in the other
three phasesa Control Protocol, which delivers Instruction Messages from a
Controller to a MA, detailing what Measurement Tasks the MA should
perform and when, and how it should report the Measurement Results.
It also delivers Capabilities, Failure and logging Information from
a MA to its Controller. Finally, it allows the Controller to update
the MA's configuration.the actual Measurement Tasks, which measure some performance or
reliability parameter(s) associated with the transfer of packets.
The LMAP work does not define Metrics and Measurement Methods, these
are define elsewhere (e.g. IPPM).a Report Protocol, which delivers Reports from a MA to a
Collector. The Report contains the Measurement Results.The diagrams show the various LMAP messages and uses the following
convention:(optional): indicated by round brackets[potentially repeated]: indicated by square bracketsThe 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. LMAP defines a specific Control
Protocol and Report Protocol, but others could be defined by other
standards bodies or be proprietary. However it is important that they
all implement the same Information Model and protocol model, in order to
ease the definition, operation and interoperability of large-scale
measurement systems.The primary purpose of bootstrapping is to enable a MA to be
integrated into a measurement system. The MA retrieves information
about itself (like its identity in the measurement system) and about
the Controller, the Controller learns information about the MA, and
they learn about security information to communicate (such as
certificates and credentials).Whilst this memo considers the bootstrapping process, it is beyond
the scope of initial LMAP work to define a bootstrap mechanism, as it
depends on the type of device and access.As a result of the bootstrapping process the MA learns information
with the following aims ( defines the consequent list
of information elements):its identifier, either its MA-ID or a device identifier such as
its MAC(optionally) a Group-ID. A Group-ID would be shared by several
MAs and could be useful for privacy reasons. For instance,
reporting the Group-ID and not the MA-ID could hinder tracking of
a mobile devicethe Control Channel, which is defined by:the address which identifies the Control Channel, such as
the Controller's FQDN (Fully Qualified Domain Name) )security information (for example to enable the MA to
decrypt the Instruction Message and encrypt messages sent to
the Controller)The details of the bootstrapping process are device /access
specific. For example, the information could be in the firmware,
manually configured or transferred via a protocol like TR-069 . There may be a multi-stage process where the MA
contacts the device at a 'hard-coded' address, which replies with the
bootstrapping information.The MA must learn its MA-ID before getting an Instruction, either
during Bootstrapping or via configuration (Section 5.2.1).The primary purpose of the Control Protocol is to allow the
Controller to configure a Measurement Agent with an Instruction about
what Measurement Tasks to do, when to do them, and how to report the
Measurement Results (Section 5.2.2). The Measurement Agent then acts
on the Instruction autonomously. The Control Protocol also enables the
MA to inform the Controller about its Capabilities and any Failure and
logging Information (Section 5.2.2). Finally, the Control Protocol
allows the Controller to update the MA's configuration.Configuration allows the Controller to update the MA about some
or all of the information that it obtained during the bootstrapping
process: the MA-ID, the (optional) Group-ID and the Control Channel.
The measurement system might use Configuration for several reasons.
For example, the bootstrapping process could ‘hard code’
the MA with details of an initial Controller, and then the initial
Controller could configure the MA with details about the Controller
that sends Instruction Messages. (Note that a MA only has one
Control Channel, and so is associated with only one Controller, at
any moment.)Note that an implementation may choose to combine Configuration
information and an Instruction Message into a single message.The Instruction is the description of the Measurement Tasks for a
Measurement Agent to do and the details of the Measurement Reports
for it to send. In order to update the Instruction the Controller
uses the Control Protocol to send an Instruction Message over the
Control Channel.The Instruction defines information with the following aims
( defines the
consequent list of information elements):the Measurement Task configurations, each of which
needs:the Metric, specified as a URI to a registry entry; it
includes the specification of a Measurement Method. The
registry could be defined by the IETF , locally by
the operator of the measurement system or perhaps by another
standards organisation.the Measurement Method role. For some Measurement
Methods, different parties play different roles; for example
(figure A3 in the Appendix) an iperf sender and receiver.
Each Metric and its associated Measurement Method will
describe all measurement roles involved in the process.
Thus, the Measurement Method role is an Input Parameter.a boolean flag (supppress or do-not-suppress) indicating
how such a Measurement Task is impacted by a Suppression
message (see Section 5.2.2.1). Thus, the flag is an Input
Parameter. any Input Parameters that need to be set for the Metric
and the Measurement Method, such as the address of a
Measurement Peer (or other Measurement Agent) that may be
involved in a Measurement Task, and for the measurement
protocol used, such as protocol role(s).if the device with the MA has multiple interfaces, then
the interface to use (if not defined, then the default
interface is used)configuration of the Measurement Schedules, each of which
needs:the timing of when the Measurement Tasks are to be
performed. Possible types of timing are periodic,
calendar-based periodic, one-off immediate and one-off at a
future timeconfiguration of the Report Channels, each of which
needs:the address of the Collector, for instance its URLsecurity for this Report Channel, for example the X.509
certificateconfiguration of the Report Schedules, each of which
needs:the timing of when reporting is to be performed. For
instance, every hour or immediately.Suppression information, if any (see Section 5.2.1.1)A single Instruction Message may contain some or all of the above
parts. The finest level of granularity possible in an Instruction
Message is determined by the implementation and operation of the
Control Protocol. For example, a single Instruction Message may add
or update an individual Measurement Schedule - or it may only update
the complete set of Measurement Schedules; a single Instruction
Message may update both Measurement Schedules and Measurement Task
configurations - or only one at a time; and so on.The MA informs the Controller that it has successfully understood
the Instruction Message, or that it cannot action the Instruction -
for example, if it doesn't include a parameter that is mandatory for
the requested Metric and Measurement Method, or it is missing
details of the target Collector.The Instruction Message instructs the MA; the Control Protocol
does not allow the MA to negotiate, as this would add complexity to
the MA, Controller and Control Protocol for little benefit.The Instruction may include Suppression information. The
purpose of Suppression is to enable the Controller to instruct the
MA not to perform Measurement Tasks. It is used if the measurement
system wants to eliminate inessential traffic, because there is
some unexpected network issue for example. The Suppression information may include any of the following
optional fields:a set of Measurement Tasks to suppress; the others are not
suppressed. For example, this could be useful if a particular
Measurement Task is overloading a Measurement Peer.a set of Measurement Schedules to suppress; the others are
not suppressed. For example, suppose the measurement system
has defined two Schedules, one with the most critical
Measurement Tasks and the other with less critical ones that
create a lot of Active Measurement Traffic, then it may only
want to suppress the second.if the Suppression information includes neither a set of
Measurement Tasks nor a set of Measurement Schedules, then the
MA does not begin new Measurement Tasks that have the boolean
flag set to "suppress"; however, the MA does begin new
Measurement Tasks that have the flag set to
"do-not-suppress".a start time, at which suppression begins. If absent, then
Suppression begins immediately.an end time, at which suppression ends. If absent, then
Suppression continues until the MA receives an un-Suppress
message.a demand that the MA ends its on-going Active Measurement
Task(s) immediately (and deletes the associated partial
Measurement Result(s)). If absent, the MA completes on-going
Measurement Tasks.So the default action (if none of the optional fields is set)
is that the MA does not begin any new Measurement Task with the
"suppress" flag.An un-Suppress message instructs the MA no longer to suppress,
meaning that the MA once again begins new Measurement Tasks,
according to its Measurement Schedule. Note that Suppression is not intended to permanently stop a
Measurement Task (instead, the Controller should send a new
Measurement Schedule), nor to permanently disable a MA (instead,
some kind of management action is suggested).The Control Protocol also enables the MA to inform the Controller
about various information, such as its Capabilities and any
Failures. It is also possible to use a device-specific mechanism
which is beyond the scope of the initial LMAP work.Capabilities are information about the MA that the Controller
needs to know in order to correctly instruct the MA, such as:the Measurement Method (roles) that the MA supportsthe measurement protocol types and roles that the MA
supportsthe interfaces that the MA hasthe version of the MAthe version of the hardware, firmware or software of the
device with the MAbut not dynamic information like the currently unused CPU,
memory or battery life of the device with the MA.Failure information concerns why the MA has been unable to
execute a Measurement Task or deliver a Report, for example:the Measurement Task failed to run properly because the MA
(unexpectedly) has no spare CPU cyclesthe MA failed record the Measurement Results because it
(unexpectedly) is out of spare memorya Report failed to deliver Measurement Results because the
Collector (unexpectedly) is not respondingbut not if a Measurement Task correctly doesn't start. For
example, the first step of some Measurement Methods is for the
MA to check there is no cross-traffic.Logging information concerns how the MA is operating and may help
debugging, for example:the last time the MA ran a Measurement Taskthe last time the MA sent a Measurement Reportthe last time the MA received an Instruction Messagewhether the MA is currently Suppressing Measurement TasksCapabilities, failure and logging information are sent by the MA,
either in response to a request from the Controller (for example, if
the Controller forgets what the MA can do or otherwise wants to
resynchronize what it knows about the MA), or on its own initiative
(for example when the MA first communicates with a Controller or if
it becomes capable of a new Measurement Method). Another example of
the latter case is if the device with the MA re-boots, then the MA
should notify its Controller in case its Instruction needs to be
updated; to avoid a "mass calling event" after a widespread power
restoration affecting many MAs, it is sensible for an MA to pause
for a random delay, perhaps in the range of one minute or so.This LMAP framework is neutral to what the actual Measurement Task
is. It does not define Metrics and Measurement Methods, these are
defined elsewhere (e.g. IPPM).The MA carries out the Measurement Tasks as instructed, unless it
gets an updated Instruction. The MA acts autonomously, in terms of
operation of the Measurement Tasks and reporting of the Results; it
doesn't do a 'safety check' with the Controller to ask whether it
should still continue with the requested Measurement Tasks.This LMAP framework does not define a generic start and stop
process, since the correct approach depends on the particular
Measurement Task; the details are defined as part of each
Measurement Method. This section provides some general hints. The MA
does not inform the Controller about Measurement Tasks starting and
stopping.Before sending Measurement Traffic the MA may run a pre-check.
(The pre-check could be defined as a separate, preceding Task or as
the first part of a larger Task.) Action could include:the MA checking that there is no cross-traffic. In other
words, a check that the end-user isn't already sending
traffic;the MA checking with the Measurement Peer (or other
Measurement Agent involved in the Measurement Task) that it can
handle a new Measurement Task (in case, for example, the
Measurement Peer is already handling many Measurement Tasks with
other MAs);sending traffic that probes the path to check it isn't
overloaded;checking that the device with the MA has enough resources to
execute the Measurement Task reliably. Note that the designer of
the measurement system should ensure that the device's
capabilities are normally sufficient to comfortably operate the
Measurement Tasks.It is possible that similar checks continue during the
Measurement Task, especially one that is long-running and/or creates
a lot of Measurement Traffic, and might lead to it being abandoned
whilst in-progress. A Measurement Task could also be abandoned in
response to a "suppress" message (see Section 5.2.1). Action could
include:For ‘upload’ tests, the MA not sending
trafficFor ‘download’ tests, the MA closing the TCP
connection or sending a TWAMP Stop control message .The Controller may want a MA to run the same Measurement Task
indefinitely (for example, "run the 'upload speed' Measurement Task
once an hour until further notice"). To avoid the MA generating
traffic forever after a Controller has permanently failed (or
communications with the Controller have failed), the MA can be
configured with a time limit; if the MA doesn't hear from the
Controller for this length of time, then it stops operating
Measurement Tasks.It is possible that a MA starts a new Measurement Task before
another Measurement Task has completed. This may be intentional (the
way that the measurement system has designed the Measurement
Schedules), but it could also be unintentional - for instance, if a
Measurement Task has a 'wait for X' step which pauses for an
unexpectedly long time. The operator of the measurement system can
handle (or not) overlapping Measurement Tasks in any way they choose
- it is a policy or implementation issue and not the concern of
LMAP. Some possible approaches are: to configure the MA not to begin
the second Measurement Task; to start the second Measurement Task as
usual; for the action to be an Input Parameter of the Measurement
Task; and so on.It may be important to include in the Measurement Report the fact
that the Measurement Task overlapped with another.The primary purpose of the Report Protocol is to allow a
Measurement Agent to report its Measurement Results to a Collector,
along with the context in which they were obtained.The Report contains:the MA-ID or a Group-ID (to anonymise results)the actual Measurement Results, including the time they were
measuredthe details of the Measurement Task (to avoid the Collector
having to ask the Controller for this information later)perhaps the Subscriber's service parameters (see Section
5.4.1).The MA sends Reports as defined by the Instruction. It is possible
that the Instruction tells the MA to report the same Results to more
than one Collector, or to report a different subset of Results to
different Collectors. It is also possible that a Measurement Task may
create two (or more) Measurement Results, which could be reported
differently (for example, one Result could be reported periodically,
whilst the second Result could be an alarm that is created as soon as
the measured value of the Metric crosses a threshold and that is
reported immediately).Optionally, a Report is not sent when there are no Measurement
Results.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:label, or perhaps not include, Measurement Results impacted by,
for instance, cross-traffic or the Measurement Peer (or other
Measurement Agent) being busylabel Measurement Results obtained by a Measurement Task that
overlapped with anothernot report the Measurement Results if the MA believes that they
are invaliddetail when Suppression started and endedThe Subscriber's service parameters are information about his/her
broadband contract, line rate and so on. Such information is likely
to be needed to help analyse the Measurement Results, for example to
help decide whether the measured download speed is reasonable.The information could be transferred directly from the Subscriber
parameter database to the data analysis tools. It may also be
possible to transfer the information via the MA. How (and if) the MA
knows such information is likely to depend on the device type. The
MA could either include the information in a Measurement Report or
separately.The above sections have described LMAP's protocol model. Other
specifications will define the actual Control and Report Protocols,
possibly operating over an existing protocol, to be selected, for
example REST-style HTTP(S). It is also possible that a different
choice is made for the Control and Report Protocols, for example
NETCONF-YANG and IPFIX respectively.From an LMAP perspective, the Controller needs to know that the MA
has received the Instruction Message, or at least that it needs to be
re-sent as it may have failed to be delivered. Similarly the MA needs
to know about the delivery of Capabilities and Failure information to
the Controller and Reports to the Collector. How this is done depends
on the design of the Control and Report Protocols and the underlying
packet transfer mechanism.For the Control Protocol, the underlying packet transfer mechanism
could be:a 'push' protocol (that is, from the Controller to the MA)a multicast protocol (from the Controller to a group of
MAs)a 'pull' protocol. The MA periodically checks with Controller
if the Instruction has changed and pulls a new Instruction if
necessary. A pull protocol seems attractive for a MA behind a NAT
(as is typical for a MA on an end-user's device), so that it can
initiate the communications. A pull mechanism is likely to require
the MA to be configured with how frequently it should check in
with the Controller, and perhaps what it should do if the
Controller is unreachable after a certain number of attempts.a hybrid protocol. In addition to a pull protocol, the
Controller can also push an alert to the MA that it should
immediately pull a new Instruction.For the Report Protocol, the underlying packet transfer
mechanism could be:a 'push' protocol (that is, from the MA to the Collector)perhaps supplemented by the ability for the Collector to 'pull'
Measurement Results from a MA.There are several potential interactions between LMAP elements that
are beyond the scope of the initial LMAP work: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.It does not define interactions between the Collector and
Controller. It is quite likely that there will be such
interactions, optionally intermediated by the data analysis tools.
For example, if there is an "interesting" Measurement Result then
the measurement system may want to trigger extra Measurement Tasks
that explore the potential cause in more detail; or if the
Collector unexpectedly does not hear from a MA, then the
measurement system may want to trigger the Controller to send a
fresh Instruction Message to the MA.It does not define coordination between different measurement
systems. For example, it does not define the interaction of a MA
in one measurement system with a Controller or Collector in a
different measurement system. Whilst it is likely that the Control
and Report Protocols could be re-used or adapted for this
scenario, any form of coordination between different organisations
involves difficult commercial and technical issues and so, given
the novelty of large-scale measurement efforts, any form of
inter-organisation coordination is outside the scope of the
initial LMAP work. Note that a single MA is instructed by a single
Controller and is only in one measurement system.An interesting scenario is where a home contains two
independent MAs, for example one controlled by a regulator and
one controlled by an ISP. Then the Measurement Traffic of one
MA is treated by the other MA just like any other end-user
traffic.It does not consider how to prevent a malicious party "gaming
the system". For example, where a regulator is running a
measurement system in order to benchmark operators, a malicious
operator could try to identify the broadband lines that the
regulator was measuring and prioritise that traffic. It is assumed
this is a policy issue and would be dealt with through a code of
conduct for instance.It does not define how to analyse Measurement Results,
including how to interpret missing Results.It does not specifically define a end-user-controlled
measurement system, see sub-section 5.6.1.This framework concentrates on the cases where an ISP or a
regulator runs the measurement system. However, we expect that LMAP
functionality will also be used in the context of an
end-user-controlled measurement system. There are at least two ways
this could happen (they have various pros and cons):an end-user could somehow request the ISP- (or regulator-)
run measurement system to test his/her line. The ISP (or
regulator) Controller would then send an Instruction to the MA
in the usual LMAP way. Note that a user can't directly initiate
a Measurement Task on an ISP- (or regulator-) controlled MA.an end-user could deploy their own measurement system, with
their own MA, Controller and Collector. For example, the user
could implement all three functions onto the same end-user-owned
end device, perhaps by downloading the functions from the ISP or
regulator. Then the LMAP Control and Report Protocols do not
need to be used, but using LMAP's Information Model would still
be beneficial. The Measurement Peer (or other MA involved in the
Measurement Task) could be in the home gateway or outside the
home network; in the latter case the Measurement Peer is highly
likely to be run by a different organisation, which raises extra
privacy considerations.In both cases there will be some way for the end-user to initiate
the Measurement Task(s). The mechanism is outside the scope of the
initial LMAP work, but could include the user clicking a button on a
GUI or sending a text message. Presumably the user will also be able
to see the Measurement Results, perhaps summarised on a webpage. It
is suggested that these interfaces conform to the LMAP guidance on
privacy in Section 8.The Appendix has some examples of possible deployment arrangements of
Measurement Agents and Peers.The Controller should understand both the MA's LMAP Capabilities
(for instance what Metrics and Measurement Methods it can perform) and
about the MA's other capabilities like processing power and memory.
This allows the Controller to make sure that the Measurement Schedule
of Measurement Tasks and the Reporting Schedule are sensible for each
MA that it Instructs.An Instruction is likely to include several Measurement Tasks.
Typically these run at different times, but it is also possible for
them to run at the same time. Some Tasks may be compatible, in that
they do not affect each other's Results, whilst with others great care
would need to be taken.The Controller should ensure that the Measurement Tasks do not have
an adverse effect on the end user. Tasks, especially those that
generate a substantial amount of traffic, will often include a
pre-check that the user isn't already sending traffic (Section 5.3).
Another consideration is whether Measurement Traffic will impact a
Subscriber's bill or traffic cap.The different elements of the Instruction can be updated
independently. For example, the Measurement Tasks could be configured
with different Input Parameters whilst keeping the same Measurement
Schedule. In general this should not create any issues, since Metrics
and their associated Measurement Methods should be defined so their
fundamental nature does not change for a new value of Input Parameter.
There could be a problem if, for example, a Measurement Task involving
a 1kB file upload could be changed into a 1GB file upload.A measurement system may have multiple Controllers (but note the
overriding principle that a single MA is instructed by a single
Controller at any point in time (Section 4.2)). For example, there
could be different Controllers for different types of MA (home
gateways, tablets) or locations (Ipswich, Edinburgh), for load
balancing or to cope with failure of one Controller.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.The Measurement Agent could take a number of forms: a dedicated
probe, software on a PC, embedded into an appliance, or even embedded
into a gateway. A single site (home, branch office etc.) that is
participating in a measurement could make use of one or multiple
Measurement Agents or Measurement Peers in a single measurement.The Measurement Agent could be deployed in a variety of locations.
Not all deployment locations are available to every kind of
Measurement Agent. There are also a variety of limitations and
trade-offs depending on the final placement. The next sections outline
some of the locations a Measurement Agent may be deployed. This is not
an exhaustive list and combinations may also apply.A MA may be embedded on a device that is directly connected to
the network, such as a MA on a smartphone. Other examples include a
MA downloaded and installed on a subscriber's laptop computer or
tablet when the network service is provided on wired or other
wireless radio technologies, such as Wi-Fi.A Measurement Agent embedded with the site gateway, for example a
home router or the edge router of a branch office in a managed
service environment, is one of better places the Measurement Agent
could be deployed. All site-to-ISP traffic would traverse through
the gateway. So, Measurement Methods that measure user traffic could
easily be performed. Similarly, due to this user traffic visibility,
a Measurement Method that generates Measurement Traffic could ensure
it does not compete with user traffic. Generally NAT and firewall
services are built into the gateway, allowing the Measurement Agent
the option to offer its Controller-facing management interface
outside of the NAT/firewall. This placement of the management
interface allows the Controller to unilaterally contact the
Measurement Agent for instructions. However, a Measurement Agent on
a site gateway (whether end-user service-provider owned) will
generally not be directly available for over the top providers, the
regulator, end users or enterprises.The Measurement Agent could also be embedded behind a NAT, a
firewall, or both. In this case the Controller may not be able to
unilaterally contact the Measurement Agent unless either static port
forwarding or firewall pin holing is configured. Configuring port
forwarding could use protocols such as PCP ,
TR-069 or UPnP . To prop
open the firewall, the Measurement Agent could send keepalives
towards the Controller (and perhaps use these also as a network
reachability test).If the device with the Measurement Agent is single homed then
there is no confusion about what interface to measure. Similarly, if
the MA is at the gateway and the gateway only has a single WAN-side
and a single LAN-side interface, there is little confusion - for
Measurement Methods that generate Measurement Traffic, the location
of the other MA or Measurement Peer determines whether the WAN or
LAN is measured.However, the device with the Measurement Agent may be
multi-homed. For example, a home or campus may be connected to
multiple broadband ISPs, such as a wired and wireless broadband
provider, perhaps for redundancy or load- sharing. It may also be
helpful to think of dual stack IPv4 and IPv6 broadband devices as
multi-homed. More generally, Section 3.2 of describes dual-stack and
multi-homing topologies that might be encountered in a home network,
provides the current practices of
multi-interfaces hosts, and the Multiple Interfaces (mif) working
group covers cases where hosts are either directly attached to
multiple networks (physical or virtual) or indirectly (multiple
default routers, etc.). In these cases, there needs to be clarity on
which network connectivity option is being measured.One possibility is to have a Measurement Agent per interface.
Then the Controller's choice of MA determines which interface is
measured. However, if a MA can measure any of the interfaces, then
the Controller defines in the Instruction which interface the MA
should use for a Measurement Task; if the choice of interface is not
defined then the MA uses the default one. Explicit definition is
preferred if the measurement system wants to measure the performance
of a particular network, whereas using the default is better if the
measurement system wants to include the impact of the MA's interface
selection algorithm. In any case, the Measurement Result should
include the network that was measured.A MA may be embedded on a device that is part of an ISP's
network, such as a router or switch. Usually the network devices
with an embedded MA will be strategically located, such as a Carrier
Grade NAT or ISP Gateway.
gives many examples where a MA might be located within a network to
provide an intermediate measurement point on the end-to-end path.
Other examples include a network device whose primary role is to
host MA functions and the necessary measurement protocol.A Measurement Peer participates in some Measurement Methods. It may
have specific functionality to enable it to participate in a
particular Measurement Method. On the other hand, other Measurement
Methods may require no special functionality, for example if the
Measurement Agent sends a ping to example.com then the server at
example.com plays the role of a Measurement Peer.A device may participate in some Measurement Methods as a
Measurement Agent and in others as a Measurement Peer.Measurement Schedules should account for limited resources in a
Measurement Peer when instructing a MA to execute measurements with a
Measurement Peer. In some measurement protocols, such as and , the Measurement Peer
can reject a measurement session or refuse a control connection prior
to setting-up a measurement session and so protect itself from
resource exhaustion. This is a valuable capability because the MP may
be used by more than one organisation.The security of the LMAP framework should protect the interests of
the measurement operator(s), the network user(s) and other actors who
could be impacted by a compromised measurement deployment. The
measurement system must secure the various components of the system from
unauthorised access or corruption. Much of the general advice contained
in section 6 of is applicable here.We assume that each Measurement Agent (MA) will receive its
Instructions from a single organisation, which operates the Controller.
These Instructions must be authenticated (to ensure that they come from
the trusted Controller), checked for integrity (to ensure no-one has
tampered with them) and not vulnerable to replay attacks. If a malicious
party can gain control of the MA they can use it to launch DoS attacks
at targets, reduce the end user's quality of experience and corrupt the
Measurement Results that are reported to the Collector. By altering the
Measurement Tasks and/or the address that Results are reported to, they
can also compromise the confidentiality of the network user and the MA
environment (such as information about the location of devices or their
traffic). The Instruction messages also need to be encrypted to maintain
confidentiality, as the information might be useful to an attacker.The process to upgrade the firmware in an MA is outside the scope of
the initial LMAP work, similar to the protocol to bootstrap the MAs (as
specified in the charter). However, systems which provide remote upgrade
must secure authorised access and integrity of the process.Reporting by 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.Reporting by the MA must be encrypted to maintain confidentiality, to
prevent the leakage of confidential or private information. Reporting
must also be authenticated (to ensure that it comes from a trusted MA)
and not vulnerable to tampering (which can be ensured through integrity
and replay checks). It must not be possible to fool a MA into injecting
falsified data and the results must also be held and processed securely
after collection and analysis See section 8.5.2 below for additional
considerations on stored data compromise, and section 8.6 on potential
mitigations for compromise.Since Collectors will be contacted repeatedly by MAs using the
Collection Protocol to convey their recent results, a successful attack
to exhaust the communication resources would prevent a critical
operation: reporting. Therefore, all LMAP Collectors should implement
technical mechanisms to:limit the number of reporting connections from a single MA
(simultaneous, and connections per unit time).limit the transmission rate from a single MA.limit the memory/storage consumed by a single MA's reports.efficiently reject reporting connections from unknown
sources.separate resources if multiple authentication strengths are used,
where the resources should be separated according to each class of
strength.limit iteration counters to generate keys with both a lower and
upper limit, to prevent an attacking system from requesting the
maximum and causing the Controller to stall on the process (see
section 6 of ).Many of the above considerations are applicable to a "pull"
model, where the MA must contact the Controller because NAT or other
network aspect prevents Controllers from contacting MAs directly.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.The security mechanisms described above may not be strictly necessary
if the network's design ensures the LMAP components and their
communications are already secured, for example potentially if they are
all part of an ISP's dedicated management network.A malicious party could "game the system". For example, where a
regulator is running a measurement system in order to benchmark
operators, an operator could try to identify the broadband lines that
the regulator was measuring and prioritise that traffic. Normally, this
potential issue is handled by a code of conduct. It is outside the scope
of the initial LMAP work to consider the issue.The LMAP work considers privacy as a core requirement and will ensure
that by default the Control and Report Protocols operate in a
privacy-sensitive manner and that privacy features are well-defined.This section provides a set of privacy considerations for LMAP. This
section benefits greatly from the timely publication of . Privacy and security (Section 7) are related. In
some jurisdictions privacy is called data protection.We begin with a set of assumptions related to protecting the
sensitive information of individuals and organisations participating in
LMAP-orchestrated measurement and data collection.LMAP protocols need to protect the sensitive information of the
following entities, including individuals and organisations who
participate in measurement and collection of results.Individual Internet users: Persons who utilise Internet access
services for communications tasks, according to the terms of
service of a service agreement. Such persons may be a service
Subscriber, or have been given permission by the Subscriber to use
the service.Internet service providers: Organisations who offer Internet
access service subscriptions, and thus have access to sensitive
information of individuals who choose to use the service. These
organisations desire to protect their Subscribers and their own
sensitive information which may be stored in the process of
performing Measurement Tasks and collecting and Results.Regulators: Public authorities responsible for exercising
supervision of the electronic communications sector, and which may
have access to sensitive information of individuals who
participate in a measurement campaign. Similarly, regulators
desire to protect the participants and their own sensitive
information.Other LMAP system operators: Organisations who operate
measurement systems or participate in measurements in some
way.Although privacy is a protection extended to individuals, we
include discussion of ISPs and other LMAP system operators in this
section. These organisations have sensitive information involved in
the LMAP system, and many of the same dangers and mitigations are
applicable. Further, the ISPs store information on their Subscribers
beyond that used in the LMAP system (for instance billing
information), and there should be a benefit in considering all the
needs and potential solutions coherently.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 authorised Internet user sensitive
information:Sub-IP layer addresses and names (MAC address, base station ID,
SSID)IP address in usePersonal Identification (real name)Location (street address, city)Subscribed service parametersContents of traffic (activity, DNS queries, destinations,
equipment types, account info for other services, etc.)Status as a study volunteer and Schedule of Measurement
TasksExamples of Internet Service Provider sensitive information:Measurement device identification (equipment ID and IP
address)Measurement Instructions (choice of measurements)Measurement Results (some may be shared, others may be
private)Measurement Schedule (exact times)Network topology (locations, connectivity, redundancy)Subscriber billing information, and any of the above Subscriber
information known to the provider.Authentication credentials (such as certificates)Other organisations will have some combination of the lists above.
The LMAP system would not typically expose all of the information
above, but could expose a combination of items which could be
correlated with other pieces collected by an attacker (as discussed in
the section on Threats below).Measurement Methods raise different privacy issues depending on
whether they measure traffic created specifically for that purpose, or
whether they measure user traffic.Measurement Tasks conducted on user traffic store sensitive
information, however briefly this storage may be. We note that some
authorities make a distinction on time of storage, and information
that is kept only temporarily to perform a communications function is
not subject to regulation (for example, active queue management, deep
packet inspection). Such Measurement Tasks could reveal all the
websites a Subscriber visits and the applications and/or services they
use.Other types of Measurement Task are conducted on traffic which is
created specifically for the purpose. Even if a user host generates
Measurement Traffic, there is limited sensitive information about the
Subscriber present and stored in the measurement system:IP address in use (and possibly sub-IP addresses and names)Status as a study volunteer and Schedule of Measurement
TasksOn the other hand, for a service provider the sensitive information
like Measurement Results is the same for all Measurement Tasks.From the Subscriber perspective, both types of Measurement Task
potentially expose the description of Internet access service and
specific service parameters, such as subscribed rate and type of
access.This section examines each of the protocol exchanges described at a
high level in Section 5 and some example Measurement Tasks, and
identifies specific sensitive information which must be secured during
communication for each case. With the protocol-related sensitive
information identified, we can better consider the threats described
in the following section.From the privacy perspective, all entities participating in LMAP
protocols can be considered "observers" according to the definition in
. 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.Section 5.1 provides the communication model for the
Bootstrapping process.Although the specification of mechanisms for Bootstrapping the MA
are beyond the initial LMAP work scope, designers should recognize
that the Bootstrapping process is extremely powerful and could cause
an MA to join a new or different LMAP system with a different
Controller and Collector, or simply install new Metrics with
associated Measurement Methods (for example to record DNS queries).
A Bootstrap attack could result in a breach of the LMAP system with
significant sensitive information exposure depending on the
capabilities of the MA, so sufficient security protections are
warranted.The Bootstrapping process provides sensitive information about
the LMAP system and the organisation that operates it, such as Initial Controller IP address or FQDNAssigned Controller IP address or FQDNSecurity certificates and credentialsDuring the Bootstrap process for an MA located at a single
subscriber's service demarcation point, the MA receives a MA-ID
which is a persistent pseudonym for the Subscriber. Thus, the MA-ID
is considered sensitive information because it could provide the
link between Subscriber identification and Measurements Results.Also, the Bootstrap process could assign a Group-ID to the MA.
The specific definition of information represented in a Group-ID is
to be determined, but several examples are envisaged including use
as a pseudonym for a set of Subscribers, a class of service, an
access technology, or other important categories. Assignment of a
Group-ID enables anonymisation sets to be formed on the basis of
service type/grade/rates. Thus, the mapping between Group-ID and
MA-ID is considered sensitive information.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.Primarily IP addresses and pseudonyms (MA-ID, Group-ID) are
exchanged with a capability request, then measurement-related
information of interest such as the parameters, schedule, metrics,
and IP addresses of measurement devices. Thus, the measurement
Instruction contains sensitive information which must be secured.
For example, the fact that an ISP is running additional measurements
beyond the set reported externally is sensitive information, as are
the additional Measurements Tasks themselves. The Measurement
Schedule is also sensitive, because an attacker intending to bias
the results without being detected can use this information to great
advantage.An organisation operating the Controller having no service
relationship with a user who hosts the Measurement Agent *could*
gain real-name mapping to a public IP address through user
participation in an LMAP system (this applies to the Measurement
Collection protocol, as well).The high-level communication model for interactions between the
Measurement Agent and Collector is illustrated in Section 5.4. The
primary purpose of this exchange is to authenticate and collect
Measurement Results from a MA, which the MA has measured
autonomously and stored.The Measurement Results are the additional sensitive information
included in the Collector-MA exchange. Organisations collecting LMAP
measurements have the responsibility for data control. Thus, the
Results and other information communicated in the Collector protocol
must be secured.A Measurement Method involving a Measurement Peer (or second
Measurement Agent) raises potential privacy issues, although the
specification of the mechanisms is beyond the scope of the initial
LMAP work. The high-level communications model below illustrates the
various exchanges to execute such a Measurement Method and store the
Results.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.The various messages are optional, depending on the nature of the
Measurement Method. It may involve sending Measurement Traffic from
the Measurement Peer to MA, MA to Measurement Peer, or both.
Similarly, a second (or more) MAs may be involved.This exchange primarily exposes the IP addresses of
measurement devices and the inference of measurement participation
from such traffic. There may be sensitive information on key points
in a service provider's network included. There may also be access
to measurement-related information of interest such as the Metrics,
Schedule, and intermediate results carried in the Measurement
Traffic (usually a set of timestamps).If the Measurement Traffic is unencrypted, as found in many
systems today, then both timing and limited results are open to
on-path observers.Some Measurement Methods only involve a single Measurement Agent.
They raise potential privacy issues, although the specification of
the mechanisms is beyond the scope of the initial LMAP work.The high-level communications model below illustrates the
collection of user information of interest with the Measurement
Agent performing the monitoring and storage of the Results. This
particular exchange is for measurement of DNS Response Time, which
most frequently uses UDP transport.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 user sensitive information of interest
(listed above) can be collected and stored in the monitoring
scenario and so must be secured.It would also be possible for a Measurement Agent to source the
DNS query itself. But then there are few privacy concerns.Although the mechanisms for communicating results (beyond the
initial Collector) are beyond the initial LMAP work scope, there are
potential privacy issues related to a single organisation's storage
and reporting of Measurement Results. Both storage and reporting
functions can help to preserve privacy by implementing the
mitigations described below.This section indicates how each of the threats described in apply to the LMAP entities and their communication
and storage of "information of interest". Denial of Service (DOS) and
other attacks described in the Security section represent threats as
well, and these attacks are more effective when sensitive information
protections have been compromised.Section 5.1.1 of describes Surveillance
as the "observation or monitoring of and individual's communications
or activities." Hence all Measurement Methods that measure user
traffic are a form of surveillance, with inherent risks.Measurement Methods which avoid periods of user transmission
indirectly produce a record of times when a subscriber or authorised
user has used their network access service.Measurement Methods may also utilise and store a Subscriber's
currently assigned IP address when conducting measurements that are
relevant to a specific Subscriber. Since the Measurement Results are
time-stamped, they could provide a record of IP address assignments
over time.Either of the above pieces of information could be useful in
correlation and identification, described below.Section 5.1.2 of describes Stored Data
Compromise as resulting from inadequate measures to secure stored
data from unauthorised or inappropriate access. For LMAP systems
this includes deleting or modifying collected measurement records,
as well as data theft.The primary LMAP entity subject to compromise is the repository,
which stores the Measurement Results; extensive security and privacy
threat mitigations are warranted. The Collector and MA also store
sensitive information temporarily, and need protection. The
communications between the local storage of the Collector and the
repository is beyond the scope of the initial LMAP work, though this
communications channel will certainly need protection as well as the
mass storage itself.The LMAP Controller may have direct access to storage of
Subscriber information (location, billing, service parameters, etc.)
and other information which the controlling organisation considers
private, and again needs protection.Note that there is tension between the desire to store all raw
results in the LMAP Collector (for reproducibility and custom
analysis), and the need to protect the privacy of measurement
participants. Many of the compromise mitigations described in
section 8.6 below are most efficient when deployed at the MA,
therefore minimising the risks with stored results.Sections 5.2.1 and 5.2.2 of describe
Correlation as combining various pieces of information to obtain
desired characteristics of an individual, and Identification as
using this combination to infer identity.The main risk is that the LMAP system could unwittingly provide a
key piece of the correlation chain, starting with an unknown
Subscriber's IP address and another piece of information. For
example, a Subscriber utilised Internet access from 2000 to 2310
UTC, because the Measurement Tasks were deferred, or sent a name
resolution for www.example.com at 2300 UTC.Sections 5.2.3 and 5.2.4 of describes
Secondary Use as unauthorised utilisation of an individual's
information for a purpose the individual did not intend, and
Disclosure is when such information is revealed causing other's
notions of the individual to change, or confidentiality to be
violated.Measurement Methods that measure user traffic are a form of
Secondary Use, and the Subscribers' permission should be obtained
beforehand. It may be necessary to obtain the measured ISP's
permission to conduct measurements, for example when required by the
terms and conditions of the service agreement, and notification is
considered good measurement practice.For Measurement Methods that measure Measurement Traffic the
Measurement Results provide some limited information about the
Subscriber or ISP and could result in Secondary Uses. For example,
the use of the Results in unauthorised marketing campaigns would
qualify as Secondary Use. Secondary use may break national laws and
regulations, and may violate individual's expectations or
desires.This section examines the mitigations listed in section 6 of and their applicability to LMAP systems. Note that
each section in identifies the threat
categories that each technique mitigates.Section 6.1 of encourages collecting and
storing the minimal information needed to perform a task.LMAP results can be useful for general reporting about
performance and for specific troubleshooting. They need different
levels of information detail, as explained in the paragraphs
below.For general results, the results can be aggregated into large
categories (the month of March, all subscribers West of the
Mississippi River). In this case, all individual identifications
(including IP address of the MA) can be excluded, and only relevant
results are provided. However, this implies a filtering process to
reduce the information fields, because greater detail was needed to
conduct the Measurement Tasks in the first place.For troubleshooting, so that a network operator or end user can
identify a performance issue or failure, potentially all the network
information (IP addresses, equipment IDs, location), Measurement
Schedule, service configuration, Measurement Results, and other
information may assist in the process. This includes the information
needed to conduct the Measurements Tasks, and represents a need
where the maximum relevant information is desirable, therefore the
greatest protections should be applied. This level of detail is
greater than needed for general performance monitoring.As regards Measurement Methods that measure user traffic, we note
that a user may give temporary permission (to enable detailed
troubleshooting), but withhold permission for them in general. Here
the greatest breadth of sensitive information is potentially
exposed, and the maximum privacy protection must be provided. The
Collector may perform pre-storage minimisation and other mitigations
(below) to help preserve privacy.For MAs with access to the sensitive information of users (e.g.,
within a home or a personal host/handset), it is desirable for the
results collection to minimise the data reported, but also to
balance this desire with the needs of troubleshooting when a service
subscription exists between the user and organisation operating the
measurements.Section 6.1.1 of 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".Experimental methods for anonymisation of user identifiable data
(and so particularly applicable to Measurement Methods that measure
user traffic) have been identified in .
However, the findings of several of the same authors is that "there
is increasing evidence that anonymisation applied to network trace
or flow data on its own is insufficient for many data protection
applications as in ." Essentially, the details
of such Measurement Methods can only be accessed by closed
organisations, and unknown injection attacks are always less
expensive than the protections from them. However, some forms of
summary may protect the user's sensitive information sufficiently
well, and so each Metric must be evaluated in the light of
privacy.The techniques in could be applied more
successfully in Measurement Methods that generate Measurement
Traffic, where there are protections from injection attack. The
successful attack would require breaking the integrity protection of
the LMAP Reporting Protocol and injecting Measurement Results (known
fingerprint, see section 3.2 of ) for
inclusion with the shared and anonymised results, then
fingerprinting those records to ascertain the anonymisation
process.Beside anonymisation of measured Results for a specific user or
provider, the value of sensitive information can be further diluted
by summarising the results over many individuals or areas served by
the provider. There is an opportunity enabled by forming anonymity
sets based on the reference path
measurement points in . For
example, all measurements from the Subscriber device can be
identified as "mp000", instead of using the IP address or other
device information. The same anonymisation applies to the Internet
Service Provider, where their Internet gateway would be referred to
as "mp190".Section 6.1.2 of 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.Data can be de-personalised by blurring it, for example by adding
synthetic data, data-swapping, or perturbing the values in ways that
can be reversed or corrected.Sections 6.2 and 6.3 of 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. The informed consent of the Subscriber (and,
if different, the end user) may be needed, including the specific
purpose of the measurements. The approval process could involve
showing the Subscriber their measured information and results before
instituting periodic collection, or before all instances of
collection, with the option to cancel collection temporarily or
permanently.It should also be clear who is legally responsible for data
protection (privacy); in some jurisdictions this role is called the
'data controller'. It is always good practice to limit the time of
personal information storage.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.LMAP protocols, devices, and the information they store clearly
need to be secure from unauthorised access. This is the hand-off
between privacy and security considerations (Section 7). The Data
Controller has the (legal) responsibility to maintain data
protections described in the Subscriber's agreement and agreements
with other organisations.There are no IANA considerations in this memo.In this section we describe some deployment scenarios that are
feasible within the LMAP framework defined in this document.The LMAP framework defines two types of components involved in the
actual measurement task, namely the Measurement Agent (MA) and the
Measurement Peer (MP). The fundamental difference conveyed in the
definition of these terms is that the MA has a interface with the
Controller/Collector while the MP does not. The MP is broadly defined as
a function that assists the MA in the Measurement Task but has no
interface with the Controller/Collector. There are many elements in the
network that can fall into this broad definition of MP. We believe that
the MP terminology is useful to allow us to refer an element of the
network that plays a role that is conceptually important to understand
and describe the measurement task being performed. We next illustrate
these concepts by describing several deployment scenarios.A very simple example of a Measurement Peer is a web server that the
MA is downloading a web page from (such as www.example.com) in order to
perform a speed test. The web server is a MP and from its perspective,
the MA is just another client; the MP doesn't have a specific function
for assisting measurements. This is described in the figure A1.Another case that is slightly different than this would be the one of
a TWAMP-responder. This is also a MP, with a helper function, the TWAMP
server, which is specially deployed to assist the MAs that perform TWAMP
tests. Another example is with a ping server, as described in Section
2.A further example is the case of a traceroute like measurement. In
this case, for each packet sent, the router where the TTL expires is
performing the MP function. So for a given Measurement Task, there is
one MA involved and several MPs, one per hop.In figure A2 we depict the case of an OWAMP responder acting as an
MP. In this case, the helper function in addition reports results back
to the MA. So it has both a data plane and control interface with the
MA.However, it is also possible to use two Measurement Agents when
performing one way Measurement Tasks, as described in figure A3 below.
In this case, MA1 generates the traffic and MA2 receives the traffic and
send the reports to the Collector. Note that both MAs are instructed by
the Controller. MA1 receives an Instruction to send the traffic and MA2
receives an Instruction to measured the received traffic and send
Reports to the Collector.Next, we consider Measurement Methods that measure user traffic.
Traffic generated in one point in the network flowing towards a given
destination and the traffic is observed in some point along the path.
One way to implement this is that the endpoints generating and receiving
the traffic are not instructed by the Controller; hence they are MPs.
The MA is located along the path with a monitor function that measures
the traffic. The MA is instructed by the Controller to monitor that
particular traffic and to send the Report to the Collector. It is
depicted in figure A4 below.Finally, we should consider the case of a router or a switch along
the measurement path. This certainly performs an important role in the
measurement - if packets are not forwarded, the measurement task will
not work. Whilst it doesn't has an interface with the Controller or
Collector, and so fits into the definition of MP, usually it is not
particularly useful to highlight it as a MP.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.Thanks to Juergen Schoenwaelder for his detailed review of the
terminology. Thanks to Charles Cook for a very detailed review of
-02.Thanks to numerous people for much discussion, directly and on the
LMAP list (apologies to those unintentionally omitted): Alan Clark,
Alissa Cooper, Andrea Soppera, Barbara Stark, Benoit Claise, Brian
Trammell, Charles Cook, Dave Thorne, Frode Sørensen, Greg Mirsky,
Guangqing Deng, Jason Weil, Jean-Francois Tremblay, Jerome Benoit,
Joachim Fabini, Juergen Schoenwaelder, Jukka Manner, Ken Ko, Lingli
Deng, Michael Bugenhagen, Rolf Winter, Sam Crawford, Sharam Hakimi,
Steve Miller, Ted Lemon, Timothy Carey, Vaibhav Bajpai, William
Lupton.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.First WG version, copy of draft-folks-lmap-framework-00.new sub-section of possible use of Group-IDs for privacytweak to definition of Control protocolfix typo in figure in S5.4change to INFORMATIONAL track (previous version had typo'd
Standards track)new definitions for Capabilities Information and Failure
Informationclarify that diagrams show LMAP-level information flows.
Underlying protocol could do other interactions, eg to get through
NAT or for Collector to pull a Reportadd hint that after a re-boot should pause random time before
re-register (to avoid mass calling event)delete the open issue "what happens if a Controller fails"
(normal methods can handle)add some extra words about multiple Tasks in one Scheduleclarify that new Schedule replaces (rather than adds to) and
old one. Similarly for new configuration of Measurement Tasks or
Report Channels.clarify suppression is temporary stop; send a new Schedule to
permanently stop Tasksalter suppression so it is ACKedadd un-suppress messageexpand the text on error reporting, to mention Reporting
failures (as well as failures to action or execute Measurement
Task & Schedule)add some text about how to have Tasks running indefinitelyadd that optionally a Report is not sent when there are no
Measurement Resultsadd that a Measurement Task may create more than one
Measurement Resultclarify /amend /expand that Reports include the "raw"
Measurement Results - any pre-processing is left for lmap2.0add some cautionary words about what if the Collector
unexpectedly doesn't hear from a MAadd some extra words about the potential impact of Measurement
Tasksclarified various aspects of the privacy sectionupdated referencesminor tweaksalignment with the Information Model
[burbridge-lmap-information-model] as this is agreed as a WG
documentOne-off and periodic Measurement Schedules are kept separate,
so that they can be updated independentlyMeasurement Suppression in a separate sub-section. Can now
optionally include particular Measurement Tasks &/or Schedules
to suppress, and start/stop timefor clarity, concept of Channel split into Control, Report and
MA-to-Controller Channelsnumerous editorial changes, mainly arising from a very detailed
review by Charles Cookupdates following the WG Last Call, with the proposed consensus
on the various issues as detailed in
http://tools.ietf.org/agenda/89/slides/slides-89-lmap-2.pdf. In
particular:tweaked definitions, especially of Measurement Agent and
Measurement PeerInstruction - left to each implementation & deployment of
LMAP to decide on the granularity at which an Instruction Message
workswords added about overlapping Measurement Tasks (measurement
system can handle any way they choose; Report should mention if
the Task overlapped with another)Suppression: no defined impact on Passive Measurement Task;
extra option to suppress on-going Active Measurement Tasks;
suppression doesn't go to Measurement Peer, since they don't
understand Instructionsnew concept of Data Transfer Task (and therefore adjustment of
the Channel concept)enhancement of Results with Subscriber's service parameters -
could be useful, don't define how but can be included in Report to
various other sectionsvarious other smaller improvements, arising from the WGLCAppendix added with examples of Measurement Agents and Peers in
various deployment scenarios. To help clarify what these terms
mean.clarified various scoping comments by using the phrase "scope
of initial LMAP work" (avoiding "scope of LMAP WG" since this may
change in the future)added a Configuration Protocol - allows the Controller to
update the MA about information that it obtained during the
bootstrapping process (for consistency with Information Model)Removed over-detailed information about the relationship
between the different items in Instruction, as this seems more
appropriate for the information model. Clarified that the lists
given are about the aims and not a list of information elements
(these will be defined in draft-ietf-information-model).the Measurement Method, specified as a URI to a registry entry
- rather than a URNMA configured with time limit after which, if it hasn't heard
from Controller, then it stops running Measurement Tasks (rather
than this being part of a Schedule)clarified there is no distinction between how capabilities,
failure and logging information are transferred (all can be when
requested by Controller or by MA on its own initiative).removed mention of Data Transfer Tasks. This abstraction is
left to the information model i-dadded Deployment sub-section about Measurement Agent embedded
in ISP Networkvarious other smaller improvements, arising from the 2nd
WGLCclarified terminlogy around Measurement Methods and Tasks.
Since within a Method there may be several different roles
(requester and responder, for instance)Suppression: there is now the concept of a flag (boolean) which
indicates whether a Task is by default gets suppressed or not. The
optional suppression message (with list of specific tasks
/schedules to suppress) over-rides this flag.The previous bullet also means there is no need to make a
distinction between active and passive Measurement Tasks, so this
distinction is removed. removed distinction added a Configuration Protocol - allows the Controller to
update the MA about information that it obtained during the
bootstrapping process (for consistency with Information Model)The Role of Network Trace anonymisation Under AttackBurkhartACM Computer Communications Review, vol. 40, no. 1,
pp. 6-11CPE WAN Management ProtocolBoeing Computer
ServicesUPnP Device Architecture and UPnP Device Control Protocols
specificationsBoeing Computer
Services