Internet DRAFT - draft-folks-lmap-framework
draft-folks-lmap-framework
Network Working Group P. Eardley
Internet-Draft BT
Intended status: Standards Track A. Morton
Expires: March 24, 2014 AT&T Labs
M. Bagnulo
UC3M
T. Burbridge
BT
P. Aitken
A. Akhter
Cisco Systems
September 20, 2013
A framework for large-scale measurement platforms (LMAP)
draft-folks-lmap-framework-00
Abstract
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
milestone.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on March 24, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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
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
6.1. Measurement Agent (MA) . . . . . . . . . . . . . . . . . 19
6.1.1. Measurement Agent embedded in site gateway . . . . . 20
6.1.2. Measurement Agent embedded behind Site NAT /Firewall 20
6.1.3. Measurement Agent in-line with site gateway . . . . . 21
6.1.4. Measurement Agent in multi homed site . . . . . . . . 21
6.2. Measurement Peer (MP) . . . . . . . . . . . . . . . . . . 22
6.3. Controller . . . . . . . . . . . . . . . . . . . . . . . 22
6.4. Collector . . . . . . . . . . . . . . . . . . . . . . . . 23
7. Security considerations . . . . . . . . . . . . . . . . . . . 23
8. Privacy Considerations for LMAP . . . . . . . . . . . . . . . 24
8.1. Categories of Entities with Information of Interest . . . 24
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
8.4.2. Collector <-> Measurement Agent . . . . . . . . . . . 27
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
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8.5. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.5.1. Surveillance . . . . . . . . . . . . . . . . . . . . 30
8.5.2. Stored Data Compromise . . . . . . . . . . . . . . . 30
8.5.3. Correlation and Identification . . . . . . . . . . . 31
8.5.4. Secondary Use and Disclosure . . . . . . . . . . . . 31
8.6. Mitigations . . . . . . . . . . . . . . . . . . . . . . . 31
8.6.1. Data Minimization . . . . . . . . . . . . . . . . . . 31
8.6.2. Anonymity . . . . . . . . . . . . . . . . . . . . . . 33
8.6.3. Pseudonymity . . . . . . . . . . . . . . . . . . . . 33
8.6.4. Other Mitigations . . . . . . . . . . . . . . . . . . 34
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34
11. History . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
12. Informative References . . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
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.
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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 mp.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 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
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meaningful to compare measurements made of the same metric at
different times and places. For example so that the operator of a
measurement system can buy the various components from different
vendors. Today's systems are proprietary in some or all of these
aspects.
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
scale).
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
system.
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.
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.
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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.
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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
Collector.
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
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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
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to eliminate outliers, as they can severely impact the aggregated
results.
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
degradation.
The operator's OAM (Operations, Administration, and Maintenance) uses
the results from the tools.
^
|
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IPPM
+---------------+ 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
|
v
Figure 1: Schematic of main elements of an LMAP-based
measurement system
(showing the elements in and out of the scope of the LMAP WG)
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.
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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
constraints).
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
does.
o a Report Protocol, which delivers a Report from the MA to a
Collector. The Report contains the Measurement Results.
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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
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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 |
+-----------------+ +-------------+
Instruction:
[(Measurement Task (parameters)), ->
(Measurement Schedule),
(Report Channel(s))]
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<- ACK
(Capability request) ->
<- List of Measurement
Methods
ACK ->
Suppress ->
<- Failure report:
(reason)
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
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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
stopping.
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
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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.
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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 |===================================| 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
measured
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
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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
MAs.
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.
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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
considerations.
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
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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
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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
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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.
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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.
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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
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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
Information:
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
Tasks
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)
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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
communications.
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.
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_________________ _________________
| | | |
| Controller |=========== NAT ? ==========| Meas Agent |
|_________________| |_________________|
<- Key Negotiation &
Encryption Setup
Encrypted Channel ->
Established
Request Capabilities ->
Equipment ID & Status
<- Reply Equipment ID
Capabil. & Status
Measurement ->
Instruction
(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 ->
Established
Request Capabilities? ->
Equipment ID & Status
<- Reply Equipment ID
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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
results.
_________________ _________________
| | | |
| Meas Peer |=========== NAT ? ==========| Meas Agent |
|_________________| |_________________|
<- Key Negotiation &
Encryption Setup
Encrypted Channel ->
Established
Announce Capabilities ->
& Status
<- Select Capabilities
ACK ->
<- Measurement Request
(MA+MP IPAddrs,set of
Metrics, Schedule)
ACK ->
Measurement Traffic <> Measurement Traffic
(may/may not be encrypted) (may/may not be encrypted)
<- Stop Tests
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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
scenario.
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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.
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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
www.example.com 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
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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
measurements.
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.
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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
set".
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
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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 of three individual drafts: draft-eardley-
lmap-terminology-02, draft-akhter-lmap-framework-00, and draft-
eardley-lmap-framework-02.
Thanks to numerous people for much discussion, directly and on the
LMAP list. This document tries to capture the current conclusions.
Thanks to Juergen Schoenwaelder for his detailed review of the
terminology.
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
12. Informative References
[I-D.linsner-lmap-use-cases]
Linsner, M., Eardley, P., and T. Burbridge, "Large-Scale
Broadband Measurement Use Cases", draft-linsner-lmap-use-
cases-03 (work in progress), July 2013.
[lmap-yang]
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, "A YANG Data Model for LMAP Measurement Agents", ,
<http://tools.ietf.org/html/draft-schoenw-lmap-yang>.
[lmap-netconf]
, "Considerations on using NETCONF with LMAP Measurement
Agents", ,
<http://tools.ietf.org/html/draft-schoenw-lmap-netconf>.
[lmap-ipfix]
, "An LMAP application for IPFIX", ,
<http://tools.ietf.org/html/draft-bagnulo-lmap-ipfix>.
[registry]
, , , , , "A registry for commonly used metrics.
Independent registries", , <http://tools.ietf.org/html/
draft-bagnulo-ippm-new-registry-independent>.
[RFC6241] , , , , "Network Configuration Protocol (NETCONF)", ,
<http://tools.ietf.org/html/rfc6241>.
[yang-api]
, "YANG-API Protocol", ,
<http://tools.ietf.org/html/rfc6241>.
[schulzrinne]
, , , "Large-Scale Measurement of Broadband Performance:
Use Cases, Architecture and Protocol Requirements", ,
<http://tools.ietf.org/html/draft-schulzrinne-lmap-
requirements>.
[information-model]
Burbridge, T., Eardley, P., Bagnulo, M., and J.
Schoenwaelder, "Information Model for Large-Scale
Measurement Platforms (LMAP)", , <http://tools.ietf.org/
html/draft-burbridge-lmap-information-model>.
[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",
http://www.itu.int/rec/T-REC-Q.1741.7/en, November 2011.
[I-D.bagnulo-ippm-new-registry-independent]
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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
1998.
[I-D.mathis-ippm-model-based-metrics]
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.
[I-D.burbridge-lmap-information-model]
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
2013.
Authors' Addresses
Philip Eardley
British Telecom
Adastral Park, Martlesham Heath
Ipswich
ENGLAND
Email: philip.eardley@bt.com
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Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown, NJ
USA
Email: acmorton@att.com
Marcelo Bagnulo
Universidad Carlos III de Madrid
Av. Universidad 30
Leganes, Madrid 28911
SPAIN
Phone: 34 91 6249500
Email: marcelo@it.uc3m.es
URI: http://www.it.uc3m.es
Trevor Burbridge
British Telecom
Adastral Park, Martlesham Heath
Ipswich
ENGLAND
Email: trevor.burbridge@bt.com
Paul Aitken
Cisco Systems, Inc.
96 Commercial Street
Edinburgh, Scotland EH6 6LX
UK
Email: paitken@cisco.com
Aamer Akhter
Cisco Systems, Inc.
7025 Kit Creek Road
RTP, NC 27709
USA
Email: aakhter@cisco.com
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