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Versions: (draft-burbridge-lmap-information-model) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 RFC 8193

Network Working Group                                       T. Burbridge
Internet-Draft                                                P. Eardley
Intended status: Standards Track                                      BT
Expires: January 4, 2016                                      M. Bagnulo
                                        Universidad Carlos III de Madrid
                                                        J. Schoenwaelder
                                                Jacobs University Bremen
                                                            July 3, 2015


     Information Model for Large-Scale Measurement Platforms (LMAP)
                  draft-ietf-lmap-information-model-06

Abstract

   This Information Model applies to the Measurement Agent within a
   Large-Scale Measurement Platform.  As such it outlines the
   information that is (pre-)configured on the MA or exists in
   communications with a Controller or Collector within an LMAP
   framework.  The purpose of such an Information Model is to provide a
   protocol and device independent view of the MA that can be
   implemented via one or more Control and Report protocols.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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 January 4, 2016.






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Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notation  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  LMAP Information Model  . . . . . . . . . . . . . . . . . . .   4
     3.1.  Pre-Configuration Information . . . . . . . . . . . . . .   8
       3.1.1.  Definition of ma-preconfig-obj  . . . . . . . . . . .   9
     3.2.  Configuration Information . . . . . . . . . . . . . . . .  10
       3.2.1.  Definition of ma-config-obj . . . . . . . . . . . . .  11
     3.3.  Instruction Information . . . . . . . . . . . . . . . . .  12
       3.3.1.  Definition of ma-instruction-obj  . . . . . . . . . .  14
       3.3.2.  Definition of ma-suppression-obj  . . . . . . . . . .  15
     3.4.  Logging Information . . . . . . . . . . . . . . . . . . .  16
       3.4.1.  Definition of ma-log-obj  . . . . . . . . . . . . . .  17
     3.5.  Capability and Status Information . . . . . . . . . . . .  17
       3.5.1.  Definition of ma-status-obj . . . . . . . . . . . . .  18
       3.5.2.  Definition of ma-task-status-obj  . . . . . . . . . .  18
       3.5.3.  Definition of ma-interface-obj  . . . . . . . . . . .  19
     3.6.  Reporting Information . . . . . . . . . . . . . . . . . .  20
       3.6.1.  Definition of ma-report-obj . . . . . . . . . . . . .  22
       3.6.2.  Definition of ma-report-task-obj  . . . . . . . . . .  23
       3.6.3.  Definition of ma-report-row-obj . . . . . . . . . . .  23
     3.7.  Common Objects: Schedules . . . . . . . . . . . . . . . .  24
       3.7.1.  Definition of ma-schedule-obj . . . . . . . . . . . .  25
       3.7.2.  Definition of ma-action-obj . . . . . . . . . . . . .  26
     3.8.  Common Objects: Channels  . . . . . . . . . . . . . . . .  27
       3.8.1.  Definition of ma-channel-obj  . . . . . . . . . . . .  28
     3.9.  Common Objects: Task Configurations . . . . . . . . . . .  28
       3.9.1.  Definition of ma-task-obj . . . . . . . . . . . . . .  30
       3.9.2.  Definition of ma-option-obj . . . . . . . . . . . . .  30
     3.10. Common Objects: Event Information . . . . . . . . . . . .  31
       3.10.1.  Definition of ma-event-obj . . . . . . . . . . . . .  32
       3.10.2.  Definition of ma-periodic-obj  . . . . . . . . . . .  33



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       3.10.3.  Definition of ma-calendar-obj  . . . . . . . . . . .  33
       3.10.4.  Definition of ma-one-off-obj . . . . . . . . . . . .  35
       3.10.5.  Definition of ma-immediate-obj . . . . . . . . . . .  35
       3.10.6.  Definition of ma-startup-obj . . . . . . . . . . . .  36
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  36
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  36
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  37
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  37
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  37
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  37
   Appendix A.  Open Issues  . . . . . . . . . . . . . . . . . . . .  37
   Appendix B.  Non-editorial Changes since -05  . . . . . . . . . .  38
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

1.  Introduction

   A large-scale measurement platform is a collection of components that
   work in a coordinated fashion to perform measurements from a large
   number of vantage points.  The main components of a large-scale
   measurement platform are the Measurement Agents (hereafter MAs), the
   Controller(s) and the Collector(s).

   The MAs are the elements actually performing the measurements.  The
   MAs are controlled by exactly one Controller at a time and the
   Collectors gather the results generated by the MAs.  In a nutshell,
   the normal operation of a large-scale measurement platform starts
   with the Controller instructing a set of one or more MAs to perform a
   set of one or more Measurement Tasks at a certain point in time.  The
   MAs execute the instructions from a Controller, and once they have
   done so, they report the results of the measurements to one or more
   Collectors.  The overall framework for a Large Measurement platform
   as used in this document is described in detail in
   [I-D.ietf-lmap-framework].

   A large-scale measurement platform involves basically three types of
   protocols, namely, a Control protocol (or protocols) between a
   Controller and the MAs, a Report protocol (or protocols) between the
   MAs and the Collector(s) and several measurement protocols between
   the MAs and Measurement Peers (MPs), used to actually perform the
   measurements.  In addition some information is required to be
   configured on the MA prior to any communication with a Controller.

   This document defines the information model for both Control and the
   Report protocols along with pre-configuration information that is
   required on the MA before communicating with the Controller, broadly
   named as the LMAP Information Model.  The measurement protocols are
   out of the scope of this document.




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   As defined in [RFC3444], the LMAP Information Model defines the
   concepts involved in a large-scale measurement platform at a high
   level of abstraction, independent of any specific implementation or
   actual protocol used to exchange the information.  It is expected
   that the proposed information model can be used with different
   protocols in different measurement platform architectures and across
   different types of MA devices (e.g., home gateway, smartphone, PC,
   router).  A YANG data model implementing the information model can be
   found in [I-D.ietf-lmap-yang].

   The definition of an Information Model serves a number of purposes:

   1.  To guide the standardisation of one or more Control and Report
       protocols and data models

   2.  To enable high-level inter-operability between different Control
       and Report protocols by facilitating translation between their
       respective data models such that a Controller could instruct sub-
       populations of MAs using different protocols

   3.  To form agreement of what information needs to be held by an MA
       and passed over the Control and Report interfaces and support the
       functionality described in the LMAP framework

   4.  Enable existing protocols and data models to be assessed for
       their suitability as part of a large-scale measurement system

2.  Notation

   This document uses a programming language-like notation to define the
   properties of the objects of the information model.  An optional
   property is enclosed by square brackets, [ ], and a list property is
   indicated by two numbers in angle brackets, <m..n>, where m indicates
   the minimal number of values, and n is the maximum.  The symbol * for
   n means no upper bound.

3.  LMAP Information Model

   The information described herein relates to the information stored,
   received or transmitted by a Measurement Agent as described within
   the LMAP framework [I-D.ietf-lmap-framework].  As such, some subsets
   of this information model are applicable to the measurement
   Controller, Collector and any device management system that pre-
   configures the Measurement Agent.  The information described in these
   models will be transmitted by protocols using interfaces between the
   Measurement Agent and such systems according to a Data Model.

   For clarity the information model is divided into six sections:



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   1.  Pre-Configuration Information.  Information pre-configured on the
       Measurement Agent prior to any communication with other
       components of the LMAP architecture (i.e., the Controller,
       Collector and Measurement Peers), specifically detailing how to
       communicate with a Controller and whether the device is enabled
       to participate as an MA.

   2.  Configuration Information.  Update of the pre-configuration
       information during the registration of the MA or subsequent
       communication with the Controller, along with the configuration
       of further parameters about the MA (rather than the Tasks it
       should perform) that were not mandatory for the initial
       communication between the MA and a Controller.

   3.  Instruction Information.  Information that is received by the MA
       from the Controller pertaining to the Tasks that should be
       executed.  This includes the task execution Schedules (other than
       the Controller communication Schedule supplied as
       (pre)configuration information) and related information such as
       the Task Configuration, communication Channels to Collectors and
       schedule Timing information.  It also includes Task Suppression
       information that is used to over-ride normal Task execution.

   4.  Logging Information.  Information transmitted from the MA to the
       Controller detailing the results of any configuration operations
       along with error and status information from the operation of the
       MA.

   5.  Capability and Status Information.  Information on the general
       status and capabilities of the MA.  For example, the set of
       measurements that are supported on the device.

   6.  Reporting Information.  Information transmitted from the MA to
       one or more Collectors including measurement results and the
       context in which they were conducted.

   In addition the MA may hold further information not described herein,
   and which may be optionally transferred to or from other systems
   including the Controller and Collector.  One example of information
   in this category is subscriber or line information that may be
   extracted by a task and reported by the MA in the reporting
   communication to a Collector.

   It should also be noted that the MA may be in communication with
   other management systems which may be responsible for configuring and
   retrieving information from the MA device.  Such systems, where
   available, can perform an important role in transferring the pre-




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   configuration information to the MA or enabling/disabling the
   measurement functionality of the MA.

   The Information Model is divided into sub-sections for a number of
   reasons.  Firstly the grouping of information facilitates reader
   understanding.  Secondly, the particular groupings chosen are
   expected to map to different protocols or different transmissions
   within those protocols.

   The granularity of data transmitted in each operation of the Control
   and Report Protocols is not dictated by the Information Model.  For
   example, the Instruction object may be delivered in a single
   operation.  Alternatively, Schedules and Task Configurations may be
   separated or even each Schedule/Task Configuration may be delivered
   individually.  Similarly the Information Model does not dictate
   whether data is read, write, or read/write.  For example, some
   Control Protocols may have the ability to read back Configuration and
   Instruction information which have been previously set on the MA.
   Lastly, while some protocols may simply overwrite information (for
   example refreshing the entire Instruction Information), other
   protocols may have the ability to update or delete selected items of
   information.

   The information in these six sections is captured by a number of
   common information objects.  These objects are also described later
   in this document and comprise of:

   1.  Schedules.  A set of Schedules tell the MA to do something.
       Without a Schedule no Task (from a measurement to reporting or
       communicating with the Controller) is ever executed.  Schedules
       are used within the Instruction to specify what tasks should be
       performed, when, and how to direct their results.  A Schedule is
       also used within the pre-Configuration and Configuration
       information in order to execute the Task or Tasks required to
       communicate with the Controller.

   2.  Channels.  A set of Channel objects are used to communicate with
       a number of endpoints (i.e., the Controller and Collectors).
       Each Channel object contains the information required for the
       communication with a single endpoint such as the target location
       and security details.

   3.  Task Configurations.  A set of Task Configurations is used to
       configure the Tasks that are run by the MA.  This includes the
       registry entries for the Task and any configuration parameters.
       Task Configurations are referenced from a Schedule in order to
       specify what Tasks the MA should execute.




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   4.  Events.  A set of Event objects that can be referenced from the
       Schedules.  Each Schedule always references exactly one Event
       object.  An Event object specifies either a singleton or series
       of events that indicate when Tasks should be executed.  A
       commonly used kind of Event objects are Timing objects.

   Figure 1 illustrates the structure in which these common information
   objects are referenced.  The references are achieved by each object
   (Task Configuration, Event) being given a short textual name that is
   used by other objects.  The objects shown in parenthesis are part of
   the internal object structure of a Schedule.  Channels are not shown
   in the diagram since they are only used as an option by selected Task
   Configurations but are similarly referenced using a short text name.

           Schedule
              |------> Event
              |------> Action 1
              |            |------> Task Configuration
              |            `------> Destination Schedule
              :
              :
              `------> Action N
                           |------> Task Configuration
                           `------> Destination Schedule

      Figure 1: Relationship between Schedules, Events, Actions, Task
                 Configurations, and Destination Schedules

   It should be clear that the top-level behavior of an MA is simply to
   execute Schedules.  Every Action referenced by a Schedule is defined
   as a Task.  As such, these Actions are configured through Task
   Configurations and executed according to the Event object referenced
   by the Schedule in which they appear.  Note, however, that Actions
   can have Action specific parameters.

   Tasks can implement a variety of different types of actions.  While
   in terms of the Information Model, all Tasks have the same structure,
   it can help conceptually to think of different Task categories:

   1.  Measurement Tasks measure some aspect of network performance or
       traffic.  They may also capture contextual information from the
       MA device or network interfaces such as the device type or
       interface speed.

   2.  Data Transfer Tasks

       A.  Reporting Tasks report the results of Measurement Tasks to
           Collectors



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       B.  Control Task(s) implement the Control Protocol and
           communicate with the Controller.  Depending on the Control
           Protocol there may be a number of specialist tasks such as:
           Configuration Task; Instruction Task; Suppression Task;
           Capabilities Task; Logging Task etc.

   3.  Data Analysis Tasks can exist to analyse data from other
       Measurement Tasks locally on the MA

   4.  Data Management Tasks may exist to clean-up, filter or compress
       data on the MA such as Measurement Task results

   Figure 1 indicates that Actions can produce data that is fed into
   Destination Schedules.  This can by used by Actions implementing
   Measurement Tasks to feed measurement results to a Schedule that
   triggers Actions implementing Reporting Tasks.

3.1.  Pre-Configuration Information

   This information is the minimal information that needs to be pre-
   configured to the MA in order for it to successfully communicate with
   a Controller during the registration process.  Some of the Pre-
   Configuration Information elements are repeated in the Configuration
   Information in order to allow an LMAP Controller to update these
   items.  The pre-configuration information also contains some elements
   that are not under the control of the LMAP framework (such as the
   device identifier and device security credentials).

   This Pre-Configuration Information needs to include a URL of the
   initial Controller from where configuration information can be
   communicated along with the security information required for the
   communication including the certificate of the Controller (or the
   certificate of the Certification Authority which was used to issue
   the certificate for the Controller).  All this is expressed as a
   Channel.  While multiple Channels may be provided in the Pre-
   Configuration Information they must all be associated with a single
   Controller (e.g., over different interfaces or network protocols).

   Where the MA pulls information from the Controller, the Pre-
   Configuration Information also needs to contain the timing of the
   communication with the Controller as well as the nature of the
   communication itself (such as the protocol and data to be
   transferred).  The timing is given as a Schedule that executes the
   Task(s) responsible for communication with the Controller.  It is
   this Task (or Tasks) that implement the Control protocol between the
   MA and the Controller and utilises the Channel information.  The
   Task(s) may take additional parameters in which case a Task
   Configuration can also be included.



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   Even where information is pushed to the MA from the Controller
   (rather than pulled by the MA), a Schedule still needs to be
   supplied.  In this case the Schedule will simply execute a Controller
   listener task when the MA is started.  A Channel is still required
   for the MA to establish secure communication with the Controller.

   It can be seen that these Channels, Schedules and Task Configurations
   for the initial MA-Controller communication are no different in terms
   of the Information Model to any other Channel, Schedule or Task
   Configuration that might execute a Measurement Task or report the
   measurement results (as described later).

   The MA may be pre-configured with an MA ID, or may use a Device ID in
   the first Controller contact before it is assigned an MA ID.  The
   Device ID may be a MAC address or some other device identifier
   expressed as a URI.  If the MA ID is not provided at this stage then
   it must be provided by the Controller during Configuration.

3.1.1.  Definition of ma-preconfig-obj

     object {
         [uuid                ma-agent-id;]
          ma-task-obj         ma-control-tasks<1..*>;
          ma-channel-obj      ma-control-channels<1..*>;
          ma-schedule-obj     ma-control-schedules<1..*>;
         [uri                 ma-device-id;]
          credentials         ma-credentials;
     } ma-preconfig-obj;

   The ma-preconfig-obj is essentially a subset of the ma-config-obj
   described below.  The ma-preconfig-obj consists of the following
   elements:

   ma-agent-id:              An optional uuid uniquely identifying the
                             measurement agent.

   ma-control-tasks:         A collection of tasks objects.

   ma-control-channels:      A collection of channel objects.

   ma-control-schedules:     A collection of scheduling objects.

   ma-device-id:             An optional identifier for the device.

   ma-credentials:           The security credentials used by the
                             measurement agent.





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3.2.  Configuration Information

   During registration or at any later point at which the MA contacts
   the Controller (or vice-versa), the choice of Controller, details for
   the timing of communication with the Controller or parameters for the
   communication Task(s) can be changed (as captured by the Channels,
   Schedules and Task Configurations objects).  For example the pre-
   configured Controller (specified as a Channel or Channels) may be
   over-ridden with a specific Controller that is more appropriate to
   the MA device type, location or characteristics of the network (e.g.,
   access technology type or broadband product).  The initial
   communication Schedule may be over-ridden with one more relevant to
   routine communications between the MA and the Controller.

   While some Control protocols may only use a single Schedule, other
   protocols may use several Schedules (and related data transfer Tasks)
   to update the Configuration Information, transfer the Instruction
   Information, transfer Capability and Status Information and send
   other information to the Controller such as log or error
   notifications.  Multiple Channels may be used to communicate with the
   same Controller over multiple interfaces (e.g., to send logging
   information over a different network).

   In addition the MA will be given further items of information that
   relate specifically to the MA rather than the measurements it is to
   conduct or how to report results.  The assignment of an ID to the MA
   is mandatory.  If the MA Agent ID was not optionally provided during
   the pre-configuration then one must be provided by the Controller
   during Configuration.  Optionally a Group ID may also be given which
   identifies a group of interest to which that MA belongs.  For example
   the group could represent an ISP, broadband product, technology,
   market classification, geographic region, or a combination of
   multiple such characteristics.  Where the Measurement Group ID is set
   an additional flag (the Report MA ID flag) is required to control
   whether the Measurement Agent ID is also to be reported.  The
   reporting of a Group ID without the MA ID allows the MA to remain
   anonymous, which may be particularly useful to prevent tracking of
   mobile MA devices.

   Optionally an MA can also be configured to stop executing any
   Instruction Schedule if the Controller is unreachable.  This can be
   used as a fail-safe to stop Measurement and other Tasks being
   conducted when there is doubt that the Instruction Information is
   still valid.  This is simply represented as a time window in seconds
   since the last communication with the Controller after which
   Instruction Schedules are to be suspended.  The appropriate value of
   the time window will depend on the specified communication Schedule
   with the Controller and the duration for which the system is willing



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   to tolerate continued operation with potentially stale Instruction
   Information.

   While Pre-Configuration Information is persistent upon device reset
   or power cycle, the persistency of the Configuration Information may
   be device dependent.  Some devices may revert back to their pre-
   configuration state upon reboot or factory reset, while other devices
   may store all Configuration and Instruction information in persistent
   storage.  A Controller can check whether an MA has the latest
   Configuration and Instruction information by examining the Capability
   and Status information for the MA.

   It should be noted that control schedules and tasks cannot be
   suppressed as evidenced by the lack of suppression information in the
   Configuration.  The control schedule must only reference tasks listed
   as control tasks (i.e., within the Configuration information).  Any
   suppress-by-default flag against control tasks will be ignored.

3.2.1.  Definition of ma-config-obj

     object {
         uuid                ma-agent-id;
         ma-task-obj         ma-control-tasks<1..*>;
         ma-channel-obj      ma-control-channels<1..*>;
         ma-schedule-obj     ma-control-schedules<1..*>;
        [uri                 ma-device-id;]
         credentials         ma-credentials;
        [string              ma-group-id;]
        [boolean             ma-report-agent-id;]
        [int                 ma-controller-timeout;]
     } ma-config-obj;

   The ma-config-obj consists of the following elements:

   ma-agent-id:              A uuid uniquely identifying the measurement
                             agent.

   ma-control-tasks:         A collection of task objects.

   ma-control-channels:      A collection of channel objects.

   ma-control-schedules:     A collection of scheduling objects.

   ma-device-id:             An optional identifier for the device.

   ma-credentials:           The security credentials used by the
                             measurement agent.




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   ma-group-id:              An optional identifier of the group of
                             measurement agents this measurement agent
                             belongs to.

   ma-report-agent-id:       An optional flag indicating whether the
                             identifier (ma-agent-id) should be included
                             in reports.

   ma-controller-timeout:    A timer is started after each successful
                             contact with a controller.  When the timer
                             reaches the controller-timeout (measured in
                             seconds), all schedules will be disabled,
                             i.e., no new actions will be executed (and
                             hence no new tasks started).  The disabled
                             schedules will be reenabled automatically
                             once contact with a controller has been
                             established successfully again.  Note that
                             this will not affect the execution of
                             actions that are essential to establish
                             contact with the controller or that perform
                             critical housekeeping functions.

3.3.  Instruction Information

   The Instruction information model has four sub-elements:

   1.  Instruction Task Configurations

   2.  Report Channels

   3.  Instruction Schedules

   4.  Suppression

   The Instruction supports the execution of all Tasks on the MA except
   those that deal with communication with the Controller (specified in
   (pre-)configuration information).  The Tasks are configured in
   Instruction Task Configurations and included by reference in
   Instruction Schedules that specify when to execute them.  The results
   can be communicated to other Schedules or a Task may implement a
   Reporting Protocol and communicate results over Report Channels.
   Suppression is used to temporarily stop the execution of new Tasks as
   specified by the Instruction Schedules (and optionally to stop
   ongoing Tasks).

   A Task Configuration is used to configure the mandatory and optional
   parameters of a Task.  It also serves to instruct the MA about the




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   Task including the ability to resolve the Task to an executable and
   specifying the schema for the Task parameters.

   A Report Channel defines how to communicate with a single remote
   system specified by a URL.  A Report Channel is used to send results
   to single Collector but is no different in terms of the Information
   Model to the Control Channel used to transfer information between the
   MA and the Controller.  Several Report Channels can be defined to
   enable results to be split or duplicated across different
   destinations.  A single Channel can be used by multiple (reporting)
   Task Configurations to transfer data to the same Collector.  A single
   Reporting Task Configuration can also be included in multiple
   Schedules.  E.g., a single Collector may receive data at three
   different cycle rates, one Schedule reporting hourly, another
   reporting daily and a third specifying that results should be sent
   immediately for on-demand measurement tasks.  Alternatively multiple
   Report Channels can be used to send Measurement Task results to
   different Collectors.  The details of the Channel element is
   described later as it is common to several objects.

   Instruction Schedules specify which Actions to execute according to a
   given triggering Event.  An Action is a Task with additional specific
   parameters.  An Event can trigger the execution of a single Action or
   it can trigger a repeated series of Actions.  The Schedule also
   specifies how to link Tasks output data to other Schedules.

   Measurement Suppression information is used to over-ride the
   Instruction Schedule and temporarily stop measurements or other Tasks
   from running on the MA for a defined or indefinite period.  While
   conceptually measurements can be stopped by simply removing them from
   the Measurement Schedule, splitting out separate information on
   Measurement Suppression allows this information to be updated on the
   MA on a different timing cycle or protocol implementation to the
   Measurement Schedule.  It is also considered that it will be easier
   for a human operator to implement a temporary explicit suppression
   rather than having to move to a reduced Schedule and then roll-back
   at a later time.

   The explicit Suppression instruction message is able to simply
   enable/disable all Instruction Tasks (that are enabled for default
   suppression) as well as having fine control on which Tasks are
   suppressed.  Suppression of both specified Task Configurations and
   Measurement Schedules is supported.  Support for disabling specific
   Task Configurations allows malfunctioning or mis-configured Tasks or
   Task Configurations that have an impact on a particular part of the
   network infrastructure (e.g., a particular Measurement Peer) to be
   targeted.  Support for disabling specific Schedules allows for
   particularly heavy cycles or sets of less essential Measurement Tasks



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   to be suppressed quickly and effectively.  Note that Suppression has
   no effect on either Controller Tasks or Controller Schedules.

   When no tasks or schedules are explicitly listed, all Instruction
   tasks will be suppressed (or not) as indicated by the suppress-by-
   default flag in the Task Configuration.  If tasks or schedules are
   listed explicitly then only these listed tasks or schedules will be
   suppressed regardless of the suppress-by-default flag.  If both
   individual tasks and individual schedules are listed then only the
   listed schedules, plus the listed tasks where present in other
   schedules, will be suppressed regardless of the suppress-by-default
   flag.

   Suppression stops new Tasks from executing.  In addition, the
   Suppression information also supports an additional Boolean that is
   used to select whether on-going tasks are also to be terminated.

   Unsuppression is achieved through either overwriting the Measurement
   Suppression information (e.g., changing 'enabled' to False) or
   through the use of an End time such that the Measurement Suppression
   will no longer be in effect beyond this time.  The datetime format
   used for all elements in the information model (e.g., the suppression
   start and end dates) MUST conform to RFC 3339 [RFC3339].

   The goal when defining these four different elements is to allow each
   part of the information model to change without affecting the other
   three elements.  For example it is envisaged that the Report Channels
   and the set of Task Configurations will be relatively static.  The
   Instruction Schedule, on the other hand, is likely to be more
   dynamic, as the measurement panel and test frequency are changed for
   various business goals.  Another example is that measurements can be
   suppressed with a Suppression command without removing the existing
   Instruction Schedules that would continue to apply after the
   Suppression expires or is removed.  In terms of the Controller-MA
   communication this can reduce the data overhead.  It also encourages
   the re-use of the same standard Task Configurations and Reporting
   Channels to help ensure consistency and reduce errors.

3.3.1.  Definition of ma-instruction-obj

     object {
         ma-task-obj         ma-instruction-tasks<0..*>;
         ma-channel-obj      ma-report-channels<0..*>;
         ma-schedule-obj     ma-instruction-schedules<0..*>;
         ma-suppression-obj  ma-suppression;
     } ma-instruction-obj;

   An ma-instruction-obj consists of the following elements:



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   ma-task-obj:        A possibly empty collection of task objects.

   ma-channel-obj:     A possibly empty collection of channel objects.

   ma-schedule-obj:    A possibly empty collection of schedule objects.

   ma-suppression-obj: A suppression object.

3.3.2.  Definition of ma-suppression-obj

     object {
         boolean             ma-suppression-enabled;
        [boolean             ma-suppression-stop-running;]
        [datetime            ma-suppression-start;]
        [datetime            ma-suppression-end;]
        [string              ma-suppression-task-names<0..*>;]
        [string              ma-suppression-schedule-names<0..*>;]
     } ma-suppression-obj;

   The ma-suppression-obj consists of the following elements:

   ma-suppression-enabled:         A boolean indicating whether
                                   suppression is enabled or not.  The
                                   default value is false.

   ma-suppression-stop-running:    An optional boolean indicating
                                   whether suppression will stop any
                                   running tasks.  The default value for
                                   this boolean is false.

   ma-suppression-start:           The optional date and time when
                                   suppression starts.  The default
                                   value is 'immediate'.

   ma-suppression-end:             The optional date and time when
                                   suppression ends.  The default value
                                   is 'indefinite'.

   ma-suppression-task-names:      An optional and possibly empty
                                   collection of task names.  If not
                                   present, this defaults to all tasks.

   ma-suppression-schedule-names:  An optional and possibly empty
                                   collection of schedule names.  If not
                                   present, this defaults to all
                                   schedules.





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3.4.  Logging Information

   The MA may report on the success or failure of Configuration or
   Instruction communications from the Controller.  In addition further
   operational logs may be produced during the operation of the MA and
   updates to capabilities may also be reported.  Reporting this
   information is achieved in exactly the same manner as scheduling any
   other Task.  We make no distinction between a Measurement Task
   conducting an active or passive network measurement and one which
   solely retrieves static or dynamic information from the MA such as
   capabilities or logging information.  One or more logging tasks can
   be programmed or configured to capture subsets of the Logging
   Information.  These logging tasks are then executed by Schedules
   which also specify that the resultant data is to be transferred over
   the Controller Channels.

   The type of Logging Information will fall into three different
   categories:

   1.  Success/failure/warning messages in response to information
       updates from the Controller.  Failure messages could be produced
       due to some inability to receive or parse the Controller
       communication, or if the MA is not able to act as instructed.
       For example:

       *  "Measurement Schedules updated OK"

       *  "Unable to parse JSON"

       *  "Missing mandatory element: Measurement Timing"

       *  "'Start' does not conform to schema - expected datetime"

       *  "Date specified is in the past"

       *  "'Hour' must be in the range 1..24"

       *  "Schedule A refers to non-existent Measurement Task
          Configuration"

       *  "Measurement Task Configuration X registry entry Y not found"

       *  "Updated Measurement Task Configurations do not include M used
          by Measurement Schedule N"

   2.  Operational updates from the MA.  For example:

       *  "Out of memory: cannot record result"



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       *  "Collector 'collector.example.com' not responding"

       *  "Unexpected restart"

       *  "Suppression timeout"

       *  "Failed to execute Measurement Task Configuration H"

   3.  Status updates from the MA.  For example:

       *  "Device interface added: eth3"

       *  "Supported measurements updated"

       *  "New IP address on eth0: xxx.xxx.xxx.xxx"

   This Information Model document does not detail the precise format of
   logging information since it is to a large extent protocol and MA
   specific.  However, some common information can be identified.

3.4.1.  Definition of ma-log-obj

     object {
         uuid                ma-log-agent-id;
         datetime            ma-log-event-time;
         code                ma-log-code;
         string              ma-log-description;
     } ma-log-obj;

   The ma-log-obj models the generic aspects of a logging object and
   consists of the following elements:

   ma-log-agent-id:          A uuid uniquely identifying the measurement
                             agent.

   ma-log-event-time:        The date and time of the event reported in
                             the logging object.

   ma-log-code:              A machine readable code describing the
                             event.

   ma-log-description:       A human readable description of the event.

3.5.  Capability and Status Information

   The MA will hold Capability Information that can be retrieved by a
   Controller.  Capabilities include the device interface details
   available to Measurement Tasks as well as the set of Measurement



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   Tasks/Roles (specified by registry entries) that are actually
   installed or available on the MA.  Status information includes the
   times that operations were last performed such as contacting the
   Controller or producing Reports.

3.5.1.  Definition of ma-status-obj

     object {
         uuid                    ma-agent-id;
         uri                     ma-device-id;
         string                  ma-hardware;
         string                  ma-firmware;
         string                  ma-version;
         ma-interface-obj        ma-interfaces<0..*>;
         datetime                ma-last-started;
        [ma-task-status-obj      ma-task-status<0..*>;]
     } ma-status-obj;

   The ma-status-obj provides status information about the measurement
   agent and consists of the following elements:

   ma-agent-id:              A uuid uniquely identifying the measurement
                             agent.

   ma-device-id:             A URI identifying the device.

   ma-hardware:              A description of the hardware of the device
                             the measurement agent is running on.

   ma-firmware:              A description of the firmware of the device
                             the measurement agent is running on.

   ma-version:               The version of the measurement agent.

   ma-interfaces:            A list of network interfaces available on
                             the device.

   ma-last-started:          The date and time the measurement agent
                             last started.

   ma-task-status:           An optional list of status objects for each
                             supported task.

3.5.2.  Definition of ma-task-status-obj







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     object {
         string              ma-task-name;
         uri                 ma-task-registry-entries<1..*>;
         [string             ma-task-role<0..*>;]
         datetime            ma-task-last-invocation;
         datetime            ma-task-last-completion;
         int                 ma-task-last-status;
         string              ma-task-last-message;
         datetime            ma-task-last-failed-completion;
         int                 ma-task-last-failed-status;
         string              ma-task-last-failed-message;
     } ma-task-status-obj;

   The ma-task-status-obj provides status information about a task and
   consists of the following elements:

   ma-task-name:                   A name uniquely identifying a task.

   ma-task-registry-entries:       A possibly empty list of URIs
                                   identifying the metrics a measurement
                                   task supports.

   ma-task-role:                   An optional and possibly empty list
                                   of roles of a task.

   ma-task-last-completion:        The date and time of the last
                                   completion of this task.

   ma-task-last-status:            The status code returned by the last
                                   execution of this task.

   ma-task-last-message:           The status message produced by the
                                   last execution of this task.

   ma-task-last-failed-completion: The date and time of the last failed
                                   completion of this task.

   ma-task-last-failed-status:     The status code returned by the last
                                   failed execution of this task.

   ma-task-last-failed-message:    The status message produced by the
                                   last failed execution of this task.

3.5.3.  Definition of ma-interface-obj







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     object {
         string              ma-interface-name;
         string              ma-interface-type;
        [int                 ma-interface-speed;]
        [string              ma-interface-link-layer-address;]
        [ip-address          ma-interface-ip-addresses<0..*>];
        [ip-address          ma-interface-gateways<0..*>;]
        [ip-address          ma-interface-dns-servers<0..*>;]
     } ma-interface-obj;

   The ma-interface-obj provides status information about network
   interfaces and consists of the following elements:

   ma-interface-name:                A name uniquely identifying a
                                     network interface.

   ma-interface-type:                The type of the network interface.

   ma-interface-speed:               An optional indication of the speed
                                     of the interface (measured in bits-
                                     per-second).

   ma-interface-link-layer-address:  An optional link-layer address of
                                     the interface.

   ma-interface-ip-addresses:        An optional list of IP addresses
                                     assigned to the interface.

   ma-interface-gateways:            An optional list of gateways
                                     assigned to the interface.

   ma-interface-dns-servers:         An optional list of DNS servers
                                     assigned to the interface.

3.6.  Reporting Information

   At a point in time specified by a Schedule, the MA will execute a
   task or tasks that communicate a set of measurement results to the
   Collector.  These Reporting Tasks will be configured to transmit task
   results over a specified Report Channel to a Collector.

   It should be noted that the output from Tasks does not need to be
   sent to communication Channels.  It can alternatively, or
   additionally, be sent to other Tasks on the MA.  This facilitates
   using a first Measurement Task to control the operation of a later
   Measurement Task (such as first probing available line speed and then
   adjusting the operation of a video testing measurement) and also to
   allow local processing of data to output alarms (e.g., when



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   performance drops from earlier levels).  Of course, subsequent Tasks
   also include Tasks that implement the reporting protocol(s) and
   transfer data to one or more Collector(s).

   The Report generated by a Reporting Task is structured hierarchically
   to avoid repetition of report header and Measurement Task
   Configuration information.  The report starts with the timestamp of
   the report generation on the MA and details about the MA including
   the optional Measurement Agent ID and Group ID (controlled by the
   Configuration Information).

   Much of the report Information is optional and will depend on the
   implementation of the Reporting Task and any parameters defined in
   the Task Configuration for the Reporting Task.  For example some
   Reporting Tasks may choose not to include the Measurement Task
   Configuration or scheduled task parameters, while others may do so
   dependent on the Controller setting a configurable parameter in the
   Task Configuration.

   It is possible for a Reporting Task to send just the Report header
   (datetime and optional agent ID and/or Group ID) if no measurement
   data is available.  Whether to send such empty reports again is
   dependent on the implementation of the Reporting Task and potential
   Task Configuration parameter.

   The handling of measurement data on the MA before generating a Report
   and transfer from the MA to the Collector is dependent on the
   implementation of the device, MA and/or scheduled Tasks and not
   defined by the LMAP standards.  Such decisions may include limits to
   the measurement data storage and what to do when such available
   storage becomes depleted.

   No context information, such as line speed or broadband product are
   included within the report header information as this data is
   reported by individual tasks at the time they execute.  Either a
   Measurement Task can report contextual parameters that are relevant
   to that particular measurement, or specific tasks can be used to
   gather a set of contextual and environmental data. at certain times
   independent of the reporting schedule.

   After the report header information the results are reported grouped
   according to different Measurement Task Configurations.  Each Task
   section optionally starts with replicating the Measurement Task
   Configuration information before the result headers (titles for data
   columns) and the result data rows.  The Options reported are those
   used for the scheduled execution of the Measurement Task and
   therefore include the Options specified in the Task Configuration as
   well as additional Options specified in the Scheduled Task.  The



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   Scheduled Task Options are appended to the Task Configuration Options
   in exactly the same order as they were provided to the Task during
   execution.

   The result row data includes a time for the start of the measurement
   and optionally an end time where the duration also needs to be
   considered in the data analysis.

   Some Measurement Tasks may optionally include an indication of the
   cross-traffic although the definition of cross-traffic is left up to
   each individual Measurement Task.  Some Measurement Tasks may also
   output other environmental measures in addition to cross-traffic such
   as CPU utlilisation or interface speed.

   Where the Configuration and Instruction information represent
   information transmitted via the Control Protocol, the Report
   represents the information that is transmitted via the Report
   Protocol.  It is constructed at the time of sending a report and
   represents the inherent structure of the information that is sent to
   the Collector.

3.6.1.  Definition of ma-report-obj

     object {
         datetime            ma-report-date;
        [uuid                ma-report-agent-id;]
        [string              ma-report-group-id;]
        [ma-report-task-obj  ma-report-tasks<0..*>];
     } ma-report-obj;

   The ma-report-obj provides the meta-data of a single report and
   consists of the following elements:

   ma-report-date:           The date and time when the report was sent
                             to a collector.

   ma-report-agent-id:       An optional uuid uniquely identifying the
                             measurement agent.

   ma-report-group-id:       An optional identifier of the group of
                             measurement agents this measurement agent
                             belongs to.

   ma-report-tasks:          An optional and possibly empty list of
                             tasks result objects.






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3.6.2.  Definition of ma-report-task-obj

     object {
         string              ma-report-task-name;
        [uri                 ma-report-task-registry-entries<1..*>;]
        [ma-option-obj       ma-report-task-options<0..*>];
        [ma-option-obj       ma-report-task-action-options<0..*>];
        [string              ma-report-task-cycle-id;]
        [string              ma-report-task-column-labels<0..*>;]
        [ma-report-row-obj   ma-report-task-rows<0..*>;]
     } ma-report-task-obj;

   The ma-report-task-obj provides the meta-data of a result report of a
   single task.  It consists of the following elements:

   ma-report-task-name:              A name uniquely identifying the
                                     task that produced the results
                                     being reported.

   ma-report-task-registry-entries:  An optional possibly empty list of
                                     URIs identifying the metrics
                                     reported.

   ma-report-task-options:           An optional list of task options
                                     provided by the task object.

   ma-report-task-action-options:    An optional list of action options
                                     provided by the scheduling object.

   ma-report-task-cycle-id:          An optional measurement cycle
                                     identifier.

   ma-report-task-column-labels:     An optional and possibly empty list
                                     of column labels.

   ma-report-task-rows:              An optional and possibly empty list
                                     of result rows.

3.6.3.  Definition of ma-report-row-obj

     object {
         datetime            ma-report-result-start-time;
        [datetime            ma-report-result-end-time;]
         string              ma-report-result-conflicts<0..*>;
         data                ma-report-result-values<0..*>;
     } ma-report-row-obj;





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   The ma-report-row-obj represents a result row and consists of the
   following elements:

   ma-report-result-start-time:  The date and time of the start of the
                                 measurement task that produced the
                                 reported result values.

   ma-report-result-end-time:    An optional date and time indicating
                                 when the measurement task that produced
                                 the reported result values finished.

   ma-report-result-conflicts:   A possibly empty set of names of task
                                 that might have impacted the
                                 measurement being reported.

   ma-report-result-values:      A possibly empty set of result values.
                                 When present, it contains an ordered
                                 set of values that align to the set of
                                 column labels for the report.

3.7.  Common Objects: Schedules

   A Schedule specifies the execution of a single or repeated series of
   Actions.  An Action is a Task with additional specific parameters.
   Each Schedule contains basically two elements: a list of Actions to
   be executed and an Event object for the Schedule.  The Schedule
   states what Actions to run (with what configuration) and when to run
   the Actions.

   Multiple Actions in the list of a single Measurement Schedule will be
   executed according to the execution mode of the Schedule.  In
   sequential mode, Actions will be executed sequentially and in
   parallel mode, all Actions will be executed concurrently.  In
   pipelined mode, data produced by one Action is passed to the
   subsequent Action.  Actions in different Schedules execute in
   parallel with such conflicts being reported in the Reporting
   Information where necessary.  If two or more Schedules have the same
   start time, then the two will execute in parallel.  There is no
   mechanism to prioritise one schedule over another or to mutex
   scheduled tasks.

   As well as specifying which Actions to execute, the Schedule also
   specifies how to link the data outputs from each Action to other
   Schedules.  Specifying this within the Schedule allows the highest
   level of flexibility since it is even possible to send the output
   from different executions of the same Task Configuration to different
   destinations.  A single Task producing multiple different outputs is
   expected to properly tag the different result.  An Action receiving



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   the output can then filter the results based on the tag if necessary.
   For example, a Measurement Task might report routine results to a
   data Reporting Task in a Schedule that communicates hourly via the
   Broadband PPP interface, but also outputs emergency conditions via an
   alarm Reporting Task in a different Schedule communicating
   immediately over a GPRS channel.  Note that task-to-task data
   transfer is always specified in association with the scheduled
   execution of the sending task - there is no need for a corresponding
   input specification for the receiving task.  While it is likely that
   an MA implementation will use a queue mechanism between the Schedules
   or Actions, this Information Model does not mandate or define a
   queue, or any potential associated parameters such as storage size
   and retention policies.

   When specifying the task to execute within the Schedule, i.e.,
   creating an Action, it is possible to add to the task configuration
   option parameters.  This allows the Task Configuration to determine
   the common characteristics of a Task, while selected parameters
   (e.g., the test target URL) are defined within the schedule.  A
   single Tasks Configuration can even be used multiple times in the
   same schedule with different additional parameters.  This allows for
   efficiency in creating and transferring the Instruction.  Note that
   the semantics of what happens if an option is defined multiple times
   (either in the Task Configuration, Schedule or in both) is not
   standardised and will depend upon the Task.  For example, some tasks
   may legitimately take multiple values for a single parameter.

   Where Options are specified in both the Schedule and the Task
   Configuration, the Schedule Options are appended to those specified
   in the Task Configuration.

   Example:  An Action of a Schedule references a single Measurement
      Task Configuration for measuring UDP latency.  It specifies that
      results are to be sent to a Schedule with a Reporting Action.
      This Reporting Task of the Reporting Action is executed by a
      separate Schedule that specifies that it should run hourly at 5
      minutes past the hour.  When run this Reporting Action takes the
      data generated by the UDP latency Measurement Task as well as any
      other data to be included in the hourly report and transfers it to
      the Collector over the Report Channel specified within its own
      Schedule.

3.7.1.  Definition of ma-schedule-obj








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     object {
         string              ma-schedule-name;
         ma-event-obj        ma-schedule-event;
         ma-action-obj       ma-schedule-actions<0..*>;
         string              ma-schedule-execution-mode;
     } ma-schedule-obj;

   The ma-schedule-obj is the main scheduling object.  It consists of
   the following elements:

   ma-schedule-name:           A name uniquely identifying a scheduling
                               object.

   ma-schedule-event:          An event object indicating when the
                               schedule fires.

   ma-schedule-actions:        A possibly empty list of actions to
                               invoke when the schedule fires.

   ma-schedule-execution-mode: Indicates whether the actions should be
                               executed sequentially, in parallel, or in
                               a pipelined mode (where data produced by
                               one action is passed to the subsequent
                               action).

3.7.2.  Definition of ma-action-obj

     object {
         string              ma-action-name;
         string              ma-action-task-name;
        [ma-option-obj       ma-action-task-options<0..*>];
        [string              ma-action-destinations<0..*>;]
      } ma-action-obj;

   The ma-action-obj models an a task together with its schedule
   specific options and destination tasks.  It consists of the following
   elements:

   ma-action-name:           A name uniquely identifying an action of a
                             scheduling object.

   ma-action-task-name:      A name identifying the task to be invoked
                             by the action.

   ma-action-task-options:   An optional and possibly empty list of
                             options (name-value pairs) that are passed
                             to the task by appending them to the
                             options configured for the task object.



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   ma-action-destinations:   An optional and possibly empty list of
                             names of destination schedules that consume
                             output produced by this action.

3.8.  Common Objects: Channels

   A Channel defines a bi-directional communication channel between the
   MA and a Controller or Collector.  Multiple Channels can be defined
   to enable results to be split or duplicated across different
   Collectors.

   Each Channel contains the details of the remote endpoint (including
   location and security credential information such as the
   certificate).  The timing of when to communicate over a Channel is
   specified by the Schedule which executes the corresponding Control or
   Reporting Task.  The certificate can be the digital certificate
   associated to the FQDN in the URL or it can be the certificate of the
   Certification Authority that was used to issue the certificate for
   the FQDN (Fully Qualified Domain Name) of the target URL (which will
   be retrieved later on using a communication protocol such as TLS).
   In order to establish a secure channel, the MA will use it's own
   security credentials (in the Configuration Information) and the given
   credentials for the individual Channel end-point.

   As with the Task Configurations, each Channel is also given a text
   name by which it can be referenced as a Task Option.

   Although the same in terms of information, Channels used for
   communication with the Controller are referred to as Control Channels
   whereas Channels to Collectors are referred to as Report Channels.
   Hence Control Channels will be referenced from Control Tasks executed
   by a Control Schedule, whereas Report Channels will be referenced
   from within Reporting Tasks executed by an Instruction Schedule.

   Multiple interfaces are also supported.  For example the Reporting
   Task could be configured to send some results over GPRS.  This is
   especially useful when such results indicate the loss of connectivity
   on a different network interface.

   Example:  A Channel used for reporting results may specify that
      results are to be sent to the URL (https://collector.example.org/
      report/), using the appropriate digital certificate to establish a
      secure channel..








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3.8.1.  Definition of ma-channel-obj

     object {
         string              ma-channel-name;
         url                 ma-channel-target;
         credentials         ma-channel-credentials;
         [string             ma-channel-interface-name;]
     } ma-channel-obj;

   The ma-channel-obj consists of the following elements:

   ma-channel-name:            A unique name identifying the channel
                               object.

   ma-channel-target:          A URL identifying the target channel
                               endpoint.

   ma-channel-credentials:     The security credentials needed to
                               establish a secure channel.

   ma-channel-interface-name:  An optional name of the network interface
                               to be used.  If not present, the system
                               will select a suitable interface.

3.9.  Common Objects: Task Configurations

   Conceptually each Task Configuration defines the parameters of a Task
   that the Measurement Agent (MA) may perform at some point in time.
   It does not by itself actually instruct the MA to perform them at any
   particular time (this is done by a Schedule).  Tasks can be
   Measurement Tasks (i.e., those Tasks actually performing some type of
   passive or active measurement) or any other scheduled activity
   performed by the MA such as transferring information to or from the
   Controller and Collectors.  Other examples of Tasks may include data
   manipulation or processing Tasks conducted on the MA.

   A Measurement Task Configuration is the same in information terms to
   any other Task Configuration.  Both measurement and non-measurement
   Tasks have registry entries to enable the MA to uniquely identify the
   Task it should execute and retrieve the schema for any parameters
   that may be passed to the Task.  Registry entries are specified as a
   URI and can therefore be used to identify the Task within a namespace
   or point to a web or local file location for the Task information.
   As mentioned previously, these URIs may be used to identify the
   Measurement Task in a public namespace
   [I-D.ietf-ippm-metric-registry].





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   Example:  A Measurement Task Configuration may configure a single
      Measurement Task for measuring UDP latency.  The Measurement Task
      Configuration could define the destination port and address for
      the measurement as well as the duration, internal packet timing
      strategy and other parameters (for example a stream for one hour
      and sending one packet every 500 ms).  It may also define the
      output type and possible parameters (for example the output type
      can be the 95th percentile mean) where the measurement task
      accepts such parameters.  It does not define when the task starts
      (this is defined by the Schedule element), so it does not by
      itself instruct the MA to actually perform this Measurement Task.

   The Task Configuration will include a local short name for reference
   by a Schedule.  Task Configurations may also refer to registry
   entries as described above.  In addition the Task can be configured
   through a set of configuration Options.  The nature and number of
   these Options will depend upon the Task.  These options are expressed
   as name-value pairs although the 'value' may be a structured object
   instead of a simple string or numeric value.  The implementation of
   these name-value pairs will vary between data models.

   An Option that must be present for Reporting Tasks is the Channel
   reference specifying how to communicate with a Collector.  This is
   included in the task options and will have a value that matches a
   channel name that has been defined in the Instruction.  Similarly
   Control Tasks will have a similar option with the value set to a
   specified Control Channel.

   A reporting task might also have a flag parameter to indicate whether
   to report if there is no measurement result data pending to be
   transferred to the Collector.  In addition many tasks will also take
   as a parameter which interface to operate over.

   The Task Configuration also contains a suppress-by-default flag that
   specifies the behaviour of a default suppress instruction (that does
   not list explicit tasks or schedules).  If this flag is set to FALSE
   then the Task will not be suppressed.  It should be noted that
   Controller Tasks are not subject to the suppression instruction and
   therefore this flag will be ignored in such cases.

   In addition the Task Configuration may optionally also be given a
   Measurement Cycle ID.  The purpose of this ID is to easily identify a
   set of measurement results that have been produced by Measurement
   Tasks with comparable Options.  This ID could be manually incremented
   or otherwise changed when an Option change is implemented which could
   mean that two sets of results should not be directly compared.





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3.9.1.  Definition of ma-task-obj

     object {
         string              ma-task-name;
         uri                 ma-task-registry-entries<1..*>;
        [ma-option-obj       ma-task-options<0..*>];
        [boolean             ma-task-suppress-by-default;]
        [string              ma-task-cycle-id;]
     } ma-task-obj;

   The ma-task-obj defines a task that can be invoked.  A task can be
   referenced by its name and it contains a set of URIs to link to a
   metrics registry or a local specification of the task.  Options allow
   the configuration of task parameter (in the form of name-value
   pairs).  The ma-task-obj consists of the following elements:

   ma-task-name:                 A name uniquely identifying a task
                                 object.

   ma-task-registry-entries:     A possibly empty list of URIs
                                 identifying the metrics a measurement
                                 task supports.

   ma-task-options:              A optional and possibly empty list of
                                 options (name-value pairs) that are
                                 passed to the task.

   ma-task-suppress-by-default:  A boolean flag indicating whether the
                                 task will be suppressed by default.
                                 The default value of the flag is true.

   ma-task-cycle-id:             An optional measurement cycle
                                 identifier that can be used to identify
                                 set of measurement results that have
                                 been produced by tasks with comparable
                                 options.

3.9.2.  Definition of ma-option-obj

     object {
         string       ma-option-name;
        [object       ma-option-value;]
     } ma-option-obj;

   The ma-option-obj models a name-value pair and consists of the
   following elements:

   ma-option-name:           The name of the option.



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   ma-option-value:          The optional value of the option.

   While many of the Task Configuration Options are left to individual
   tasks to define, some common Options are used by multiple tasks and
   benefit from standardisation.  These Options are Channel and Role.

   o  Channel is used to specify the details of an endpoint for Control
      or Reporting Task communications and is detailed elsewhere in this
      document.  The common option name for specifying the channel is
      "channel".

   o  Role is used to specify which Role the task should be performing
      (as defined in the registry) if multiple roles are available.  The
      common option name for specifying the role is "role".

3.10.  Common Objects: Event Information

   The Event information object used throughout the information models
   can initially take one of five different forms.  Additional forms may
   be defined later in order to bind the execution of schedules to
   additional events.  The initially defined five Event forms are:

   1.  Periodic Timing: Emits multiple events periodically according to
       an interval time defined in milliseconds

   2.  Calendar Timing: Emits multiple events according to a calendar
       based pattern, e.g., 22 minutes past each hour of the day on
       weekdays

   3.  One Off Timing: Emits one event at a specific date and time

   4.  Immediate: Emits one event as soon as possible

   5.  Startup: Emits an event whenever the MA is started (e.g., at
       device startup)

   Optionally each of the Event options may also specify a randomness
   that should be evaluated and applied separately to each indicated
   event.  This randomness parameter defines a uniform interval in
   milliseconds over which the start of the task is delayed from the
   starting times specified by the timing object.

   Both the Periodic and Calendar timing objects allow for a series of
   Actions to be executed.  While both have an optional end time, it is
   best practice to always configure an end time and refresh the
   information periodically to ensure that lost MAs do not continue
   their tasks forever.




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   Startup events are only created on device startup, not when a new
   Instruction is transferred to the MA.  If scheduled task execution is
   desired both on the transfer of the Instruction and on device restart
   then both the Immediate and Startup timing needs to be used in
   conjunction.

   The datetime format used for all elements in the information model
   MUST conform to RFC 3339 [RFC3339].

3.10.1.  Definition of ma-event-obj

     object {
        string              ma-event-name;
        union {
            ma-periodic-obj  ma-timing-periodic;
            ma-calendar-obj  ma-timing-calendar;
            ma-one-off-obj   ma-timing-one-off;
            ma-immediate-obj ma-event-immediate;
            ma-startup-obj   ma-event-startup;
        }
        [int                 ma-event-random-spread;]
     } ma-event-obj;

   The ma-event-obj is the main event object.  Event objects are
   identified by a name.  The generic event object itself contains a
   more specific event object and the set of specific event objects
   should be extensible.  These five initial specific event objects are
   further described below.  The ma-event-obj also includes an optional
   uniform random spread in milliseconds that can be used to randomize
   the start times of scheduled tasks.  The ma-event-obj consists of the
   following elements:

   ma-timing-name:           The name uniquely identifies an event
                             object.  Schedules refer to event objects
                             by this name.

   ma-timing-periodic:       The ma-timing-periodic is present for
                             periodic timing objects.

   ma-timing-calendar:       The ma-timing-calendar is present for
                             calendar timing objects.

   ma-timing-one-off:        The ma-timing-one-off is present for one-
                             off timing objects.

   ma-timing-immediate:      The ma-event-immediate is present for
                             immediate event objects.




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   ma-timing-startup:        The ma-event-startup is present for startup
                             event objects.

   ma-timing-random-spread:  The optional ma-event-random-spread adds a
                             random delay defined in milliseconds to the
                             event object.

3.10.2.  Definition of ma-periodic-obj

     object {
        [datetime        ma-periodic-start;]
        [datetime        ma-periodic-end;]
         int             ma-periodic-interval;
     } ma-periodic-obj;

   The ma-periodic-obj timing object has an optional start and an
   optional end time plus a periodic interval.  Schedules using an ma-
   periodic-obj are started periodically between the start and end time.
   The ma-periodic-obj consists of the following elements:

   ma-periodic-start:        The optional date and time at which
                             Schedules using this object are first
                             started.  If not present it defaults to
                             immediate.

   ma-periodic-end:          The optional date and time at which
                             Schedules using this object are last
                             started.  If not present it defaults to
                             indefinite.

   ma-periodic-interval:     The interval defines the time in
                             milliseconds between two consecutive starts
                             of tasks.

3.10.3.  Definition of ma-calendar-obj

   Calendar Timing supports the routine execution of Actions at specific
   times and/or on specific dates.  It can support more flexible timing
   than Periodic Timing since the execution of Actions does not have to
   be uniformly spaced.  For example a Calendar Timing could support the
   execution of a Measurement Task every hour between 6pm and midnight
   on weekdays only.

   Calendar Timing is also required to perform measurements at
   meaningful times in relation to network usage (e.g., at peak times).
   If the optional timezone offset is not supplied then local system
   time is assumed.  This is essential in some use cases to ensure
   consistent peak-time measurements as well as supporting MA devices



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   that may be in an unknown timezone or roam between different
   timezones (but know their own timezone information such as through
   the mobile network).

   The calendar elements within the Calendar Timing do not have defaults
   in order to avoid accidental high-frequency execution of Tasks.  If
   all possible values for an element are desired then the wildcard * is
   used.

     object {
        [datetime        ma-calendar-start;]
        [datetime        ma-calendar-end;]
        [string          ma-calendar-months<0..*>;]
        [string          ma-calendar-days-of-week<0..*>;]
        [string          ma-calendar-days-of-month<0..*>;]
        [string          ma-calendar-hours<0..*>;]
        [string          ma-calendar-minutes<0..*>;]
        [string          ma-calendar-seconds<0..*>;]
        [int             ma-calendar-timezone-offset;]
     } ma-calendar-obj;

   ma-calendar-start:            The optional date and time at which
                                 Schedules using this object are first
                                 started.  If not present it defaults to
                                 immediate.

   ma-calendar-end:              The optional date and time at which
                                 Schedules using this object are last
                                 started.  If not present it defaults to
                                 indefinite.

   ma-calendar-months:           The optional set of months (1-12) on
                                 which tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 months.  If not present, it defaults to
                                 no months.

   ma-calendar-days-of-week:     The optional set of days of a week
                                 ("Mon", "Tue", "Wed", "Thu", "Fri",
                                 "Sat", "Sun") on which tasks scheduled
                                 using this object are started.  The
                                 wildcard * means all days of the week.
                                 If not present, it defaults to no days.

   ma-calendar-days-of-month:    The optional set of days of a months
                                 (1-31) on which tasks scheduled using
                                 this object are started.  The wildcard




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                                 * means all days of a months.  If not
                                 present, it defaults to no days.

   ma-calendar-hours:            The optional set of hours (0-23) on
                                 which tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 hours of a day.  If not present, it
                                 defaults to no hours.

   ma-calendar-minutes:          The optional set of minutes (0-59) on
                                 which tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 minutes of an hour.  If not present, it
                                 defaults to no hours.

   ma-calendar-seconds:          The optional set of seconds (0-59) on
                                 which tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 seconds of an hour.  If not present, it
                                 defaults to no seconds.

   ma-calendar-timezone-offset:  The optional timezone offest in hours.
                                 If not present, it defaults to the
                                 system's local timezone.

   If a day of the month is specified that does not exist in the month
   (e.g., 29th of Feburary) then those values are ignored.

3.10.4.  Definition of ma-one-off-obj

     object {
         datetime            ma-one-off-time;
     } ma-one-off-obj;

   The ma-one-off-obj timing object specifies a fixed point in time.
   Schedules using an ma-one-off-obj are started once at the specified
   date and time.  The ma-one-off-obj consists of the following
   elements:

   ma-one-off-time:          The date and time at which Schedules using
                             this object are started.

3.10.5.  Definition of ma-immediate-obj

     object {
                           // empty
     } ma-immediate-obj;




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   The ma-immediate-obj event object has no further information
   elements.  Schedules using an ma-immediate-obj are started as soon as
   possible.

3.10.6.  Definition of ma-startup-obj

     object {
                          // empty
     } ma-startup-obj;

   The ma-startup-obj event object has no further information elements.
   Schedules using an ma-startup-obj are started at MA initiation time.

4.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

5.  Security Considerations

   This Information Model deals with information about the control and
   reporting of the Measurement Agent.  There are broadly two security
   considerations for such an Information Model.  Firstly the
   Information Model has to be sufficient to establish secure
   communication channels to the Controller and Collector such that
   other information can be sent and received securely.  Additionally,
   any mechanisms that the Network Operator or other device
   administrator employs to pre-configure the MA must also be secure to
   protect unauthorized parties from modifying pre-configuration
   information.  These mechanisms are important to ensure that the MA
   cannot be hijacked, for example to participate in a DDoS attack.

   The second consideration is that no mandated information items should
   pose a risk to confidentiality or privacy given such secure
   communication channels.  For this latter reason items such as the MA
   context and MA ID are left optional and can be excluded from some
   deployments.  This would, for example, allow the MA to remain
   anonymous and for information about location or other context that
   might be used to identify or track the MA to be omitted or blurred.

   The Information Model should support wherever relevant, all the
   security and privacy requirements associated with the LMAP Framework.







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6.  Acknowledgements

   The notation was inspired by the notation used in the ALTO protocol
   specification.

   Philip Eardley, Trevor Burbridge, Marcelo Bagnulo and Juergen
   Schoenwaelder 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.

7.  References

7.1.  Normative References

   [I-D.ietf-lmap-framework]
              Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
              Aitken, P., and A. Akhter, "A framework for Large-Scale
              Measurement of Broadband Performance (LMAP)", draft-ietf-
              lmap-framework-12 (work in progress), March 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

7.2.  Informative References

   [I-D.ietf-ippm-metric-registry]
              Bagnulo, M., Claise, B., Eardley, P., Morton, A., and A.
              Akhter, "Registry for Performance Metrics", draft-ietf-
              ippm-metric-registry-02 (work in progress), February 2015.

   [I-D.ietf-lmap-yang]
              Schoenwaelder, J. and V. Bajpai, "A YANG Data Model for
              LMAP Measurement Agents", draft-ietf-lmap-yang-00 (work in
              progress), April 2015.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444, January
              2003.

Appendix A.  Open Issues

   o  Should the execution-mode have a default?  If so, which one?

   o  Is the current handling of lost connectivity to the controller
      sufficient?



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   o  There should be status objects for schedules and actions instead
      of tasks (since what is being invoked are schedules and actions,
      not configured tasks).  The status objects should also indicate
      whether a schedule is enabled, suppressed, disabled (e.g. due to
      loss of controller connectivity), or disabled for any other
      reason.

Appendix B.  Non-editorial Changes since -05

   o  A task can now reference multiply registry entries.

   o  Consistent usage of the term Action and Task.

   o  Schedules are triggered by Events instead of Timings; Timings are
      just one of many possible event sources.

   o  Actions feed into other Schedules (instead of Actions within other
      Schedules).

   o  Removed the notion of multiple task outputs.

   o  Support for sequential, parallel, and pipelined execution of
      Actions.

Authors' Addresses

   Trevor Burbridge
   BT
   Adastral Park, Martlesham Heath
   Ipswich  IP5 3RE
   United Kingdom

   Email: trevor.burbridge@bt.com


   Philip Eardley
   BT
   Adastral Park, Martlesham Heath
   Ipswich  IP5 3RE
   United Kingdom

   Email: philip.eardley@bt.com









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

   Email: marcelo@it.uc3m.es


   Juergen Schoenwaelder
   Jacobs University Bremen
   Campus Ring 1
   Bremen  28759
   Germany

   Email: j.schoenwaelder@jacobs-university.de



































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