A framework for large-scale measurement platforms (LMAP)
draft-ietf-lmap-framework-02
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| Authors | Philip Eardley , Al Morton , Marcelo Bagnulo , Trevor Burbridge , Paul Aitken, Aamer Akhter | ||
| Last updated | 2013-12-06 | ||
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draft-ietf-lmap-framework-02
Network Working Group P. Eardley
Internet-Draft BT
Intended status: Informational A. Morton
Expires: June 9, 2014 AT&T Labs
M. Bagnulo
UC3M
T. Burbridge
BT
P. Aitken
A. Akhter
Cisco Systems
December 6, 2013
A framework for large-scale measurement platforms (LMAP)
draft-ietf-lmap-framework-02
Abstract
Measuring broadband service on a large scale requires a description
of the logical architecture and standardisation of the key protocols
that coordinate interactions between the components. The document
presents an overall framework for large-scale measurements. It also
defines terminology for LMAP (large-scale measurement platforms).
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 9, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Outline of an LMAP-based measurement system . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 8
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 . . . . . . . . . . . . . . . . . . . . 14
5.3. Starting and stopping Measurement Tasks . . . . . . . . . 16
5.4. Report Protocol . . . . . . . . . . . . . . . . . . . . . 17
5.5. Items beyond the scope of the LMAP Protocol Model . . . . 19
5.5.1. User-controlled measurement system . . . . . . . . . 20
6. MA Deployment considerations . . . . . . . . . . . . . . . . 20
6.1. Measurement Agent embedded in site gateway . . . . . . . 21
6.2. Measurement Agent embedded behind Site NAT /Firewall . . 21
6.3. Measurement Agent in multi homed site . . . . . . . . . . 21
7. Security considerations . . . . . . . . . . . . . . . . . . . 22
8. Privacy Considerations for LMAP . . . . . . . . . . . . . . . 23
8.1. Categories of Entities with Information of Interest . . . 23
8.2. Examples of Sensitive Information . . . . . . . . . . . . 24
8.3. Key Distinction Between Active and Passive Measurement
Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.4. Privacy analysis of the Communications Models . . . . . . 26
8.4.1. MA Bootstrapping and Registration . . . . . . . . . . 26
8.4.2. Controller <-> Measurement Agent . . . . . . . . . . 27
8.4.3. Collector <-> Measurement Agent . . . . . . . . . . . 27
8.4.4. Active Measurement Peer <-> Measurement Agent . . . . 28
8.4.5. Passive Measurement Peer <-> Measurement Agent . . . 29
8.4.6. Result Storage and Reporting . . . . . . . . . . . . 29
8.5. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.5.1. Surveillance . . . . . . . . . . . . . . . . . . . . 30
8.5.2. Stored Data Compromise . . . . . . . . . . . . . . . 30
8.5.3. Correlation and Identification . . . . . . . . . . . 31
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8.5.4. Secondary Use and Disclosure . . . . . . . . . . . . 31
8.6. Mitigations . . . . . . . . . . . . . . . . . . . . . . . 31
8.6.1. Data Minimization . . . . . . . . . . . . . . . . . . 32
8.6.2. Anonymity . . . . . . . . . . . . . . . . . . . . . . 32
8.6.3. Pseudonymity . . . . . . . . . . . . . . . . . . . . 33
8.6.4. Other Mitigations . . . . . . . . . . . . . . . . . . 34
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35
11. History . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.1. From -00 to -01 . . . . . . . . . . . . . . . . . . . . 35
11.2. From -01 to -02 . . . . . . . . . . . . . . . . . . . . 35
12. Informative References . . . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
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.ietf-lmap-use-cases]. The LMAP framework should be useful for
these, as well as other use cases that the LMAP WG doesn't
concentrate on, such as to help end users run diagnostic checks like
a network speed test.
The LMAP framework has four basic elements: Measurement Agents,
Measurement Peers, Controllers and Collectors.
Measurement Agents (MAs) perform network measurements. They are
pieces of code that can be executed in specialized hardware (hardware
probe) or on a general-purpose device (like a PC or mobile phone).
The Measurement Agents may have multiple interfaces (WiFi, Ethernet,
DSL, fibre, etc.) and the measurements may specify any one of these.
Measurements may be active (the MA or Measurement Peer (MP) generates
test traffic), passive (the MA observes user traffic), or some hybrid
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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 gets
instructions from the Controller initiates the measurement tasks, 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.
The desirable features for a large-scale measurement systems we are
designing for are:
o Standardised - in terms of the tests that they perform, the
components, the data models and protocols for transferring
information between the components. For example so that it is
meaningful to compare measurements made of the same metric at
different times and places. For example so that the operator of a
measurement system can buy the various components from different
vendors. Today's systems are proprietary in some or all of these
aspects.
o Large-scale - [I-D.ietf-lmap-use-cases] envisages Measurement
Agents in every home gateway and edge device such as set-top-boxes
and tablet computers. Existing systems have up to a few thousand
Measurement Agents (without judging how much further they could
scale).
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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. 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 and we introduce the main terms needed for
the LMAP framework. The new terms are capitalized. In the next
section we provide a terminology section with a compilation of all
the LMAP terms and their definition. The subsequent sections study
the LMAP components in more detail.
A Measurement Task measures some performance or reliability Metric of
interest. An Active Measurement Task involves either a Measurement
Agent (MA) injecting Test Traffic into the network destined for a
Measurement Peer (MP), and/or a MP sending Test Traffic to a MA; one
of them measures the some parameter associated with the transfer of
the packet(s). A Passive Measurement Task involves only a MA, which
simply observes existing traffic - for example, it could simply count
bytes or it might calculate the average loss for a particular flow.
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 [I-D.bagnulo-ippm-new-registry-independent]
so that a Measurement Method can be referred to simply by its
identifier in the registry. The Measurement Methods and registry
would hopefully also be referenced by other standards organisations.
In order for a Measurement Agent and a Measurement Peer to execute an
Active Measurement Task, they exchange Active Measurement Traffic.
The protocols used for the Active Measurement Traffic is out of the
scope of the LMAP WG and falls within the scope of other IETF WGs
such as IPPM.
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.
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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 Measurement Tasks
it should perform and when. For example it may instruct a MA at a
home gateway: "Run the 'download speed test' with the Measurement
Peer at the end user's first IP point in the network; if the end user
is active then delay the test and re-try 1 minute later, with up to 3
re-tries; repeat every hour at xx.05 + Unif[0,180] seconds". 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". As well as regular Measurement Tasks, a
Controller can initiate a one-off Measurement Task ("Do measurement
now", "Report as soon as possible"). These are called the
Measurement and Report Schedule.
The Collector accepts a Report from a MA with the results from its
tests. It may also do some processing on the results - for instance
to eliminate outliers, as they can severely impact the aggregated
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
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line. Another example is if the Controller wants to run a one-off
Measurement Task to diagnose a fault, then it should understand what
problem the customer is experiencing and what Measurement Tasks have
already been run. The Subscribers' service parameters are already
gathered and stored by existing operations systems.
A Results Repository records all measurements in an equivalent form,
for example an SQL database, so that they can be easily accessed by
the Data Analysis Tools. The Data Analysis Tools also need to
understand the Subscriber's service information, for example the
broadband contract.
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.
^
|
IPPM
+---------------+ Test +-------------+ Scope
+------->| Measurement |<---------->| Measurement | v
| | Agent | Traffic | Peer | ^
| +---------------+ +-------------+ |
| ^ | |
| Instruction | | Report |
| | +-----------------+ |
| | | |
| | v LMAP
| +------------+ +------------+ Scope
| | Controller | | Collector | |
| +------------+ +------------+ v
| ^ ^ | ^
| | | | |
| | +----------+ | |
| | | v |
+------------+ +----------+ +--------+ +----------+ |
|Bootstrapper| |Subscriber|--->| Data |<---|Repository| Out
+------------+ |Parameter | |Analysis| +----------+ of
|Database | | Tools | Scope
+----------+ +--------+ |
|
v
Figure 1: Schematic of main elements of an LMAP-based
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measurement system
(showing the elements in and out of the scope of the LMAP WG)
3. 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.
Capabilities Information: The list of the Measurement Methods that
the MA can perform, plus information about the device hosting the MA
(for example its interface type and speed and its IP address).
Channel: a schedule, a target and the associated security information
for that target. In the case of a Report Channel it is a specific
Report Schedule, a Collector and its associated security information.
Collector: A function that receives a Report from a Measurement
Agent. Colloquially, a Collector is a physical device that performs
this function.
Controller: A function that provides a Measurement Agent with
Instruction(s). Colloquially, a Controller is a physical device that
performs this function.
Control Protocol: The protocol delivering Instruction(s) from a
Controller to a Measurement Agent. It also delivers Failure
Information and Capabilities Information from the Measurement Agent
to the Controller.
Cycle-ID: A tag that is sent by the Controller in an Instruction and
echoed by the MA in its Report; Measurement Results with the same
Cycle-ID are expected to be comparable.
Data Model: The implementation of an Information Model in a
particular data modelling language.
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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.
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.
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). The Report is sent by a Measurement
Agent to a 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, and to register a
user or a list of users authorized to enjoy these services. [Q1741]
Both the subscriber and service provider are allowed to set the
limits relative to the use that associated users make of subscribed
services.
Active Measurement Traffic: for Active Measurement Tasks, the traffic
generated by the Measurement Agent and/or the Measurement Peer to
execute the requested Measurement Task.
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, 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.
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However, the components of an LMAP measurement system can be deployed
in administrative domains that are not owned by the measuring
organisation. Thus, the system of functions deployed by a single
organisation constitutes a single LMAP domain which may span
ownership or other administrative boundaries.
4.2. Each MA may only have a single Controller at any point in time
A MA is instructed by one Controller and is in one measurement
system. The constraint avoids different Controllers giving a MA
conflicting instructions and so means that the MA does not have to
manage contention between multiple Measurement (or Report) Schedules.
This simplifies the design of MAs (critical for a large-scale
infrastructure) and allows a Measurement Schedule to be tested on
specific types of MA before deployment to ensure that the end user
experience is not impacted (due to CPU, memory or broadband-product
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 Active Measurement Traffic between the
Measurement Agent and a Measurement Peer, whilst a Passive
Measurement Task involves (only) the Measurement Agent observing
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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.
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
[I-D.burbridge-lmap-information-model], which is the abstract
definition of the information carried by the protocol model. The
purpose of both is to provide a protocol and device independent view,
which can be implemented via specific protocols. The LMAP WG will
define a specific Control Protocol and Report Protocol, but other
Protocols could be defined by other standards bodies or be
proprietary. However it is important that they all implement the
same Information and Protocol Model, in order to ease the definition,
operation and interoperability of large-scale measurement systems.
The diagrams show the flow of LMAP information, however there may
need to be other protocol interactions. For example, typically the
MA is behind a NAT, so it needs to initiate communications in order
that the Controller can communicate with it. The communications
channel also needs to be secured before it is used. Another example
is that the Collector may want to 'pull' Measurement Results from a
MA.
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, MA-ID)
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+-----------------+
| Initial |
| Controller |
+-----------------+
<- (register)
Controller details:
address or FQDN, ->
security credentials
+-----------------+
| |
| Controller |
+-----------------+
<- register
(MA-ID, Group-ID, report?) ->
The MA knows how to contact a Controller through some device /access
specific mechanism. For example, this could be in the firmware,
downloaded, manually configured or via a protocol like TR-069. The
Controller could either be the one that will send it Instructions
(see next sub-section) or else an initial Controller. The role of an
initial Controller is simply to inform the MA how to contact its
actual Controller; this could be useful, for example: for load
balancing; if the details of the initial Controller are statically
configured; if the measurement system has specific Controllers for
different devices types; or perhaps as a way of handling failure of
the Controller.
If the MA has not learnt its identifier (MA-ID) while bootstrapping,
it will do so when the MA registers with the Controller; it may also
be told a Group-ID and whether to include the MA-ID as well as the
Group-ID in its Reports. A Group-ID would be shared by several MAs
and could be useful for privacy reasons (for instance to hinder
tracking of a mobile MA device). The MA may also tell the Controller
its Capabilities (such as the Measurement Methods it can perform)
(see next sub-section).
If the device with the MA re-boots, then the MA need to re-register,
so that it can receive a new Instruction. To avoid a "mass calling
event" after a widespread power restoration affecting many MAs, it is
sensible for an MA to pause for a random delay (perhaps in the range
of one minute) before re-registering.
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.
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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 |
+-----------------+ +-------------+
(Capability request) ->
<- List of Measurement
Methods
ACK ->
Instruction:
[(Measurement Task (parameters)), ->
(Measurement Schedule),
(Report Channel(s))]
<- ACK
Suppress ->
<- ACK
Un-suppress ->
<- ACK
<- Failure report:
[reason]
ACK ->
The Instruction contains:
o what Measurement Tasks to do: the Measurement Methods could be
defined by reference to a registry entry, along with any
parameters that need to be set (such as the address of the
Measurement Peer) and any Environmental Constraint (such as,
'delay the measurement task if the end user is active')
o when to do them: the Measurement Schedule details the timings of
regular measurement tasks, one-off measurement tasks
o how to report the Measurement Results: via Reporting Channel(s),
each of which defines a target Collector and Report Schedule
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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.
A new Instruction replaces (rather than adds to) those elements that
it includes. For example, if the new Instruction includes (only) a
Measurement Schedule, then that replaces the old Measurement Schedule
but does not alter the configuration of the Measurement Tasks and
Report Channels.
If the Instruction includes several Measurement Tasks, these could be
scheduled to run at different times or possibly at the same time -
some Tasks may be compatible, in that they do not affect each other's
Results, whilst with others great care would need to be taken.
A Measurement Task may create more than one Measurement Result. For
example, one Result could be reported periodically, whilst another
could be an alarm that is reported immediately a the measured value
of a Metric goes below a threshold.
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).
However, the Control protocol includes a Capabilities detection
feature, through which the MA can send to the Controller the complete
list of Measurement Methods that it is capable of. Note that it is
not intended to indicate dynamic capabilities like the MA's currently
unused CPU, memory or battery life. The list of Measurement Methods
could be useful in several circumstances: when the MA first
communicates with a Controller; when the MA becomes capable of a new
Measurement Method; when requested by the Controller (for example, if
the Controller forgets what the MA can do or otherwise wants to
resynchronize what it knows about the MA).
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 create a lot of traffic. See the
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next section for more information on stopping Measurement Tasks.
Note that if a Controller wants to permanently stop a Measurement
Task, it should send a new Measurement Schedule, as suppression is
intended to temporarily stop Tasks. The Controller can send an "un-
suppress" message to indicate that the temporary problem is solved
and Active Measurement Tasks can begin again.
The figure shows that the various messages are acknowledged, which
means that they have been delivered successfully.
There is no need for the MA to confirm to the Controller that it has
understood and acted on the Instruction, since the Controller knows
the capabilities of the MA. However, the Control Protocol must
support robust error reporting by the MA, to provide the Controller
with sufficiently detailed reasons for any failures. These could
concern either the Measurement Tasks and Schedules, or the Reporting.
In both cases there are two broad categories of failure. Firstly,
the MA cannot action the Instruction (for example, it doesn't include
a parameter that is mandatory for the requested Measurement Method;
or it is missing details of the target Collector). Secondly, the MA
cannot execute the Measurement Task or deliver the Report (for
example, the MA unexpectedly has no spare CPU cycles; or the
Collector is not responding). Note that it is not considered a
failure if a Measurement Task (correctly) doesn't start - for example
if the MA detects cross-traffic; instead this is reported to the
Collector in the normal manner.
Finally, note that the MA doesn't do a 'safety check' with the
Controller (that it should still continue with the requested
Measurement Tasks) - nor does it inform the Controller about
Measurement Tasks starting and stopping. It simply carries out the
Measurement Tasks as instructed, unless it gets an updated
Instruction.
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.
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Once the MA gets its Measurement and Report Schedules from its
Controller then it acts autonomously, in terms of operation of the
Measurement Tasks and reporting of the result. One implication is
that the MA initiates Measurement Tasks. As an example, for the
common case where the MA is on a home gateway, the MA initiates a
'download speed test' by asking a Measurement Peer to send the file.
Many Active Measurement Tasks begin with a pre-check before the test
traffic is sent. Action could include:
o the MA checking that there is no cross-traffic (ie that the user
isn't already sending traffic);
o the MA checking with the Measurement Peer that it can handle a new
Measurement Task (in case the MP is already handling many
Measurement Tasks with other MAs);
o the first part of the Measurement Task consisting of traffic that
probes the path to make sure it isn't overloaded.
It is possible that similar checks continue during the Measurement
Task, especially one that is long-running &/or creates a lot of Test
Traffic, which may be abandoned whilst in-progress. A Measurement
Task could also be abandoned in response to a "suppress" message (see
previous section). Action could include:
o For 'upload' tests, the MA not sending traffic
o For 'download' tests, the MA closing the TCP connection or sending
a TWAMP Stop control message.
The Controller may want a MA to run the same Measurement Task
indefinitely (for example, "run the 'upload speed' Measurement Task
once an hour until further notice"). To avoid the MA generating
traffic forever after a Controller has permanently failed, it is
suggested that the Measurement Schedule includes a time limit ("run
the 'upload speed' Measurement Task once an hour for the next 30
days") and that the Measurement Schedule is updated regularly (say,
every 10 days).
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 |
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| Collector |===================================| Agent |
+-----------------+ +-------------+
<- Report:
[MA-ID &/or Group-ID,
Measurement Results,
Measurement Task]
ACK ->
The MA acts autonomously in terms of reporting; it simply sends
Reports as defined by the Controller's Instruction.
The Report contains:
o the MA's identifier, or perhaps a Group-ID to anonymise results
o the actual Measurement Results, including the time they were
measured
o the details of the Measurement Task (to avoid the Collector having
to ask the Controller for this information later)
The MA may report the Results to more than one Collector, if the
Instruction says so. It could also report a different subset of
Results to different Collectors.
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 pre-process Measurement
Results before it reports them. Potential examples of pre-processing
by the MA are:
o labelling, or perhaps not including, Measurement Results impacted
by for instance cross-traffic or the MP being busy
o detailing the start and end of suppression
o filtering outlier Results
o calculating some statistic like average (beyond that defined by
the Measurement Task itself)
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The measurement system may define what happens if a Collector
unexpectedly does not hear from a MA. Possible solutions could
include the ability for a Collector to 'pull' Measurement Results
from a MA, or (after an out-of-scope indication from the Collector to
the Controller) for the Controller to send a fresh Report Schedule to
the MA. The measurement system also needs to consider carefully how
to interpret missing Results; for example, if the missing Results are
ignored and the lack of a Report is caused by its broadband being
broken, then the estimate of overall performance, averaged across all
MAs, would be too optimistic.
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
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one controlled by an ISP. Then the test traffic of one MA is
treated by the other MA just like any other user traffic.
4. It does not specifically define a user-initiated measurement
system, see sub-section.
5.5.1. User-controlled measurement system
The WG concentrates on the cases where an ISP or a regulator runs the
measurement system. However, we expect that LMAP functionality will
also be used in the context of an end user-controlled measurement
system. There are at least two ways this could happen (they have
various pros and cons):
1. a user could somehow request the ISP- (or regulator-) run
measurement system to test his/her line. The ISP (or regulator)
Controller would then send an Instruction to the MA in the usual
LMAP way. Note that a user can't directly initiate a Measurement
Task on an ISP- (or regulator-) controlled MA.
2. a user could deploy their own measurement system, with their own
MA, Controller and Collector. For example, the user could
download all three functions onto the same user-owned end device;
then the LMAP Control and Report protocols do not need to be
used, but using LMAP's Information Model would still be
beneficial. The MP could be in the home gateway or outside the
home network; in the latter case the MP is highly likely to be
run by a different organisation, which raises extra privacy
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. MA Deployment considerations
The Measurement Agent could take a number of forms: a dedicated
probe, software on a PC, embedded into an appliance, or even embedded
into a gateway. A single site (home, branch office etc.) that is
participating in a measurement could make use of one or multiple
Measurement Agents in a single measurement e.g., if there are
multiple output interfaces, there might be a Measurement Agent per
interface.
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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. 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.
6.2. Measurement Agent embedded behind Site NAT /Firewall
The Measurement Agent could also be embedded behind a NAT, a
firewall, or both. In this case the Controller may not be able to
unilaterally contact the Measurement Agent unless either static port
forwarding configuration or firewall pin holing is configured. This
would require user intervention, and ultimately might not be an
option available to the user (perhaps due to permissions). The
Measurement Agent may originate a session towards the Controller and
maintain the session for bidirectional communications. This would
alleviate the need to have user intervention on the gateway, but
would reduce the overall scalability of the Controller as it would
have to maintain a higher number of active sessions. That said,
sending keepalives to prop open the firewall could serve a dual
purpose in testing network reachability for the Measurement Agent.
An alternative would be to use a protocol such as UPnP or PCP
[RFC6887] to control the NAT/firewall if the gateway supports this
kind of control.
6.3. 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.). [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.
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. The
measurement system must secure the various components of the system
from unauthorised access or corruption.
We assume that each Measurement Agent will receive measurement tasks
configuration, scheduling and reporting instructions from a single
organisation (operator of the Controller). These instructions must
be authenticated (to ensure that they come from the trusted
Controller), checked for integrity (to ensure no-one has tampered
with them) and be prevented from replay. If a malicious party can
gain control of the Measurement Agent they can use the MA
capabilities to launch DoS attacks at targets, reduce the network
user experience and corrupt the measurement results that are reported
to the Collector. By altering the tests that are operated and/or the
Collector address they can also compromise the confidentiality of the
network user and the MA environment (such as information about the
location of devices or their traffic).
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
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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.
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
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.
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o Internet Service Providers: Organizations who offer Internet
access service subscriptions, and thus have access to sensitive
information of Individuals who choose to use the service. These
organizations desire to protect their subscribers and their own
sensitive information which may be stored in the process of
measurement and result collection.
o Other LMAP system Operators: Organizations who operate measurement
systems or participate in measurements in some way.
Although privacy is a protection extended to individuals, we include
discussion of ISPs and other LMAP system operators in this section.
These organizations have sensitive information involved in the LMAP
system and revealed by measurements, and many of the same mitigations
are applicable. Further, the ISPs store information on their
subscribers beyond that used in the LMAP system (e.g., billing
information), and there should be a benefit in considering all the
needs and potential solutions coherently.
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 Sub-IP layer addresses and names (e.g., MAC address, BS id, SSID)
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)
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o Measurement Instructions (choice of measurements)
o Measurement Results (some may be shared, others may be private)
o Measurement Schedule (exact times)
o Network Topology (Locations, Connectivity, Redundancy)
o Subscriber billing information, and any of the above Subscriber
Information known to the provider.
o Authentication credentials (e.g., certificates)
Other organizations will have some combination of the lists above.
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).
8.3. Key Distinction Between Active and Passive Measurement Tasks
There are many possible definitions for the two main categories of
measurement types, active and passive. For the purposes of this
memo, we describe Passive and Active Measurements as follows:
Passive: measurements conducted on Internet User traffic, such that
sensitive information is present and stored in the measurement system
(however briefly this storage may be). We note that some authorities
make a distinction on time of storage, and information that is kept
only temporarily to perform a communications function is not subject
to regulation (e.g., Active Queue Management, Deep Packet
Inspection). Passive measurements could reveal all websites a
subscriber visits and the applications and/or services they use.
Active: measurements conducted on traffic which serves only the
purpose of measurement. Even if a user host generates active
measurement traffic, there is significantly limited sensitive
information about the Subscriber present and stored in the
measurement system compared to the passive case, as follows:
o IP address in use (and possibly Sub-IP addresses and names)
o Status as a study volunteer 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
(e.g., measurement results).
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Both Active and Passive measurements potentially expose the
description of Internet Access service and specific service
parameters, such as subscribed rate and type of access.
8.4. Privacy analysis of the Communications Models
This section examines each of the protocol exchanges described at a
high level in Section 5 and some example measurement tasks, and
identifies specific sensitive information which must be secured
during communication for each case. With the protocol-related
sensitive information identified, we have can better consider the
threats described in the following section.
From the privacy perspective, all entities participating in LMAP
protocols 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.
8.4.1. MA Bootstrapping and Registration
Section 5.1 provides the communication model for the Bootstrapping
process.
Although the specification of mechanisms for Bootstrapping the MA are
beyond the LMAP scope, designers should recognize that the
Bootstrapping process is extremely powerful and could cause an MA to
join a new or different LMAP system with Control/Collection entities,
or simply install new methods of measurement (e.g., a passive DNS
Query collector). A Bootstrap attack could result in a breach of the
LMAP system with significant sensitive information exposure depending
on the capabilities of the MA, so sufficient security protections are
warranted.
The Bootstrapping (or Registration) process provides sensitive
information about the LMAP system and the organization that operates
it, such as
o Initial Controller IP address or FQDN
o Assigned Controller IP address or FQDN
o Security certificates and credentials
During the Bootstrap process (or Registration process that follows),
the MA receives its MA-ID which is a persistent pseudonym for the
subscriber in the case that the MA is located at a service
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demarcation point. Thus, the MA-ID is considered sensitive
information, because it could provide the link between subscriber
identification and measurements or observations on traffic.
Also, the Bootstrap or Registration process could assign a Group-ID
to the MA. The specific definition of information represented in a
Group-ID is to be determined, but several examples are envisaged
including use as a pseudonym for a set of subscribers, a class of
service, an access technology, or other important categories.
Assignment of a Group-ID enables anonymization sets to be formed on
the basis of service type/grade/rates. Thus, the mapping between
Group-ID and MA-ID is considered sensitive information.
8.4.2. Controller <-> Measurement Agent
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 themselves. The schedule/timing of specific
measurements is also sensitive, because an attacker intending to bias
the results without being detected can use this information to great
advantage.
An organization operating the Controller having no service
relationship with a user who hosts the measurement agent *could* gain
real-name mapping to public IP address through user participation in
an LMAP system (this applies to the Measurement Collection protocol,
as well).
8.4.3. Collector <-> Measurement Agent
The high-level communication model for interactions between the LMAP
Measurement Agent and Collector is illustrated in Section 5.4. The
primary purpose of this exchange is to authenticate and collect
results from a Measurement Agent, which it has measured autonomously
and stored.
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Beyond the Controller-MA exchange, the new and highly-sensitive
information exposed in the Collector-MA exchange is the measurement
results. Organizations collecting LMAP measurements have the
responsibility for Data Control. Thus, the results and other
information communicated in the Collector protocol must be secured.
8.4.4. 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.
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.
_________________ _________________
| | | |
| Meas Peer |=========== NAT ? ==========| Meas Agent |
|_________________| |_________________|
<- Key Negotiation &
Encryption Setup
Encrypted Channel ->
Established
Announce Capabilities ->
& Status
<- Select Capabilities
ACK ->
<- Measurement Request
(MA+MP IPAddrs,set of
Metrics, Schedule)
ACK ->
Measurement Traffic <> Measurement Traffic
(may/may not be encrypted) (may/may not be encrypted)
<- Stop Tests
Return Results ->
(if applicable)
<- ACK, Close
This exchange primarily exposes the IP addresses of measurement
devices and the inference of measurement participation from such
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traffic. There may be sensitive information on key points in a
service provider's network included. There may also be access to
measurement-related information of interest such as the metrics,
schedule, and intermediate results carried in the measurement packets
(usually a set of timestamps).
If the measurement traffic is unencrypted, as found in many systems
today, then both timing and limited results are open to on-path
observers, and this should be avoided when the degradation of secure
measurement is minimal.
8.4.5. 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 sensitive information of
interest (listed above) can be collected and stored in the passive
monitoring scenario. Thus, the LMAP Collection of passive
measurements provides the additional sensitive information exposure
to a Collection-path observer, and this information must be secured.
8.4.6. Result Storage and Reporting
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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. 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 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
itself.
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 and measured ISP's
permission should be obtained before measurement. Although user
traffic is only indirectly involved, active measurement results
provide limited information about the subscriber/ISP and may
constitute secondary use. Use of the measurements in unauthorized
marketing campaigns would qualify as Secondary Use.
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.
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8.6.1. Data Minimization
Section 6.1 of [RFC6973] encourages collecting and storing the
minimal information needed to perform a task.
There are two levels of information needed for LMAP results to be
useful for a specific task: Network Operator and User
troubleshooting, and General results reporting.
The minimal supporting information for general results is conducive
to protection of sensitive information, as long as the results can be
aggregated into large categories (e.g., the month of March, all
subscribers West of the Mississippi River). In this case, all
individual identifications (including IP address of the MA) can be
excluded, and only the results applicable to the desired measurement
path are provided.. However, this implies a filtering process to
reduce the information fields allocated to this task, because greater
detail was needed to conduct the measurements in the first place.
For a Network Operator and User troubleshooting a performance issue
or failure, potentially all the network information (e.g., IP
addresses, equipment IDs, location), measurement schedule, service
configuration, measurement results and other information may assist
in the process. This includes the information needed to conduct the
measurements, and represents a need where the maximum relevant
information is desirable, therefore the greatest protections should
be applied.
We note that a user may give temporary permission for passive
measurements to enable detailed troubleshooting, but withhold
permission for passive measurements in general. Here the greatest
breadth of sensitive information is potentially exposed, and the
maximum privacy protection must be provided.
For MAs with access to the sensitive information of users (e.g.,
within a home or a personal host/handset), it is desirable for the
results collection to minimize the data reported, but also to balance
this desire with the needs of troubleshooting when a service
subscription exists between the user and organization operating the
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.
8.6.2. Anonymity
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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
handle for the device, and long-term use weakens a pseudonym's power
to obscure identity.
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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. The informed consent of the Subscriber (and, if
different, the end user) is needed, including the specific purpose of
the measurements. The approval process could involve showing the
Subscriber their measured information and results before instituting
periodic collection, or before all instances of collection, with the
option to cancel collection temporarily or permanently.
It should also be clear who is legally responsible for data
protection (privacy); in some jurisdictions this role is called the
'data controller'. It is good practice to time limit the storage of
personal information.
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 unauthorized access. This is the hand-off between
privacy and security considerations, found elsewhere in this memo.
The Data Controller has the (legal) responsibility to maintain data
protections described in the Subscriber's agreement and agreements
with other organizations.
Another standard method for de-personalising data is to blur it by
adding synthetic data, data-swapping, or perturbing the values in
ways that can be reversed or corrected.
9. IANA Considerations
There are no IANA considerations in this memo.
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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
First WG version, copy of draft-folks-lmap-framework-00.
11.1. From -00 to -01
o new sub-section of possible use of Group-IDs for privacy
o tweak to definition of Control protocol
o fix typo in figure in S5.4
11.2. From -01 to -02
o change to INFORMATIONAL track (previous version had typo'd
Standards track)
o new definitions for Capabilities Information and Failure
Information
o clarify that diagrams show LMAP-level information flows.
Underlying protocol could do other interactions, eg to get through
NAT or for Collector to pull a Report
o add hint that after a re-boot should pause random time before re-
register (to avoid mass calling event)
o delete the open issue "what happens if a Controller fails" (normal
methods can handle)
o add some extra words about multiple Tasks in one Schedule
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o clarify that new Schedule replaces (rather than adds to) and old
one. similarly for new configuration of Measurement Tasks or
Report Channels.
o clarify suppression is temporary stop; send a new Schedule to
permanently stop Tasks
o alter suppression so it is ACKed
o add un-suppress message
o expand the text on error reporting, to mention Reporting failures
(as well as failures to action or execute Measurement Task &
Schedule)
o add some text about how to have Tasks running indefinitely
o add that optionally a Report is not sent when there are no
Measurement Results
o add that a Measurement Task may create more than one Measurement
Result
o clarify /amend /expand that Reports include the "raw" Measurement
Results - any pre-processing is left for lmap2.0
o add some cautionary words about what if the Collector unexpectedly
doesn't hear from a MA
o add some extra words about the potential impact of Measurement
Tasks
o clarified varous aspects of the privacy section
o updated references
o minor tweaks
12. Informative References
[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.
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[I-D.ietf-lmap-use-cases]
Linsner, M., Eardley, P., and T. Burbridge, "Large-Scale
Broadband Measurement Use Cases", draft-ietf-lmap-use-
cases-00 (work in progress), October 2013.
[I-D.bagnulo-ippm-new-registry-independent]
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.
[I-D.ietf-homenet-arch]
Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"IPv6 Home Networking Architecture Principles", draft-
ietf-homenet-arch-11 (work in progress), October 2013.
[RFC6419] Wasserman, M. and P. Seite, "Current Practices for
Multiple-Interface Hosts", RFC 6419, November 2011.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
2013.
[RFC5533] Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming
Shim Protocol for IPv6", RFC 5533, June 2009.
[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-01 (work in progress), October 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
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Philip Eardley
British Telecom
Adastral Park, Martlesham Heath
Ipswich
ENGLAND
Email: philip.eardley@bt.com
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
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Aamer Akhter
Cisco Systems, Inc.
7025 Kit Creek Road
RTP, NC 27709
USA
Email: aakhter@cisco.com
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