Information Model for Large-Scale Measurement Platforms (LMAPs)
Description: This Information Model applies to the Measurement Agent within an LMAP framework. As such, it outlines the information that is configured or preconfigured on the Measurement Agent 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 Measurement Agent that can be implemented via one or more Control and Report Protocols.

Internet Engineering Task Force (IETF) | T. Burbridge
Request for Comments: 8193 | P. Eardley
Category: Standards Track | BT
ISSN: 2070-1721 | M. Bagnulo
| Universidad Carlos III de Madrid
| J. Schoenwaelder
| Jacobs University Bremen
| August 21, 2017

Information Model for Large-Scale Measurement Platforms (LMAPs)

# Abstract

This Information Model applies to the Measurement Agent within an LMAP framework. As such, it outlines the information that is configured or preconfigured on the Measurement Agent 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 Measurement Agent that can be implemented via one or more Control and Report Protocols.

# Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8193.

# Copyright Notice

Copyright (c) 2017 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 (https://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 to this document. Code Components extracted from this document must 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

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. A typical use case is the execution of broadband measurements [RFC7536]. The main components of a large-scale measurement platform are the Measurement Agents (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-scale measurement platform as used in this document is described in detail in [RFC7594].

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 the Control and Report Protocols along with Preconfiguration 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.

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, or router). A YANG data model implementing the Information Model can be found in [RFC8194].

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

1. To guide the standardization of one or more Control and Report protocols and data models
2. To enable high-level interoperability 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. To enable existing protocols and data models to be assessed for their suitability as part of a large-scale measurement system

# 2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

# 3. Notation

This document uses a notation similar to a programming language 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.

The object definitions use several base types that are defined as follows:

int
  A type representing signed or unsigned integer numbers. This Information Model does not define a precision nor does it make a distinction between signed and unsigned number ranges. This type is also used to represent enumerations.
boolean
  A type representing a boolean value.
string
  A type representing a human-readable string consisting of a (possibly restricted) subset of Unicode and ISO/IEC 10646 [ISO.10646] characters.
datetime
  A type representing a date and time using the Gregorian calendar. The datetime format MUST conform to RFC 3339 [RFC3339].
uuid
  A type representing a Universally Unique IDentifier (UUID) as defined in RFC 4122 [RFC4122]. The UUID values are expected to be unique within an installation of a large-scale measurement system.
uri
  A type representing a Uniform Resource Identifier as defined in STD 66 [RFC3986].
ip-address
  A type representing an IP address. This type supports both IPv4 and IPv6 addresses.
counter
  A non-negative integer that monotonically increases. Counters may have discontinuities, and they are not expected to persist across restarts.
credentials
  An opaque type representing credentials needed by a cryptographic mechanism to secure communication. Data models must expand this opaque type as needed and required by the security protocols utilized.
data
  An opaque type representing data obtained from measurements.

Names of objects are generally assumed to be unique within an implementation.

# 4. 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 [RFC7594]. As such, some subsets of this Information Model are applicable to the measurement Controller and Collector and to any device management system that preconfigures 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.

The Information Model is divided into six aspects. 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.

1. Preconfiguration Information. Information preconfigured on the Measurement Agent prior to any communication with other components of the LMAP architecture (i.e., the Controller, the 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 Preconfiguration 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 Measurement 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 Measurement Tasks that should be executed. This includes the Task execution Schedules (other than the Controller communication Schedule supplied as Configuration or Preconfiguration Information) and related information such as the Task Configuration, communication Channels to Collectors, and Event information. It also includes Task Suppression information that is used to override 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, 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 that may be responsible for configuring and retrieving information from the MA device. Such systems, where available, can perform an important role in transferring the Preconfiguration Information to the MA or enabling/disabling the measurement functionality of the MA.

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 that has 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 modeled by the six aspects of the Information Model is supported by a number of common information objects. These objects are also described later in this document and are comprised of:

1. Schedules. A set of Schedules tells the MA to execute Actions. An Action of a Schedule leads to the execution of a Task. Without a Schedule, no Task (including measurements or 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 Preconfiguration and Configuration Information in order to execute the Task or Tasks required to communicate with the Controller. A specific Schedule can only be active once. Attempts to start a Schedule while the same Schedule is still running will fail.
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, represented as Task Options. Task Configurations are referenced from a Schedule in order to specify what Tasks the MA should execute.
4. Events. A set of Event objects that can be referenced from the Schedules. Each Schedule always references exactly one Event object that determines when the Schedule is executed. An Event object specifies either a singleton or a series of Events that indicate when Tasks should be executed. A commonly used kind of Event object is the Timing object. For Event objects specifying a series of Events, it is generally a good idea to configure an end time and to refresh the end time as needed to ensure that MAs that lose connectivity to their Controller do not continue executing Schedules forever.

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
            |-- triggered by --> Event
            |
            |-- executes --> Action 1
            |                  |-- using --> Task Configuration
            |                  |
            |                  `-- feeding to --> Destination Schedule
            :
            :
            `-- executes --> Action N
                               |-- using --> Task Configuration
                               |
                               `-- feeding to --> Destination Schedule

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

The primary function of an MA is to execute Schedules. A Schedule, which is triggered by an Event, executes a number of Actions. An Action refers to a configured Task, and it may feed results to a Destination Schedule. Both Actions and configured Tasks can provide parameters, represented as Action Options and Task Options.

Tasks can implement a variety of different functions. 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 support the communication with a Controller and Collectors:
   1. Reporting Tasks report the results of Measurement Tasks to Collectors
   2. One or more Control Tasks implement the Control Protocol and communicate with the Controller
3. Data Analysis Tasks can exist to analyze data from other Measurement Tasks locally on the MA.
4. Data Management Tasks may exist to cleanup, 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. Data fed to a Destination Schedule is consumed by the first Action of the Destination Schedule if the Destination Schedule is using the sequential or pipelined execution mode, and it is consumed by all Actions of the Destination Schedule if the Destination Schedule is using parallel execution mode.

# 4.1. Preconfiguration Information

This information is the minimal information that needs to be preconfigured to the MA in order for it to successfully communicate with a Controller during the registration process. Some of the Preconfiguration Information elements are repeated in the Configuration Information in order to allow an LMAP Controller to update these items. The Preconfiguration 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 Preconfiguration 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 that was used to issue the certificate for the Controller). All this is expressed as a Channel. While multiple Channels may be provided in the Preconfiguration 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 Preconfiguration 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 represented as an Event that invokes a Schedule that executes the Task(s) responsible for communication with the Controller. It is this Task (or Tasks) that implements the Control Protocol between the MA and the Controller and utilizes the Channel information. The Task(s) may take additional parameters, as defined by a Task Configuration.

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 communication between the MA and its Controller 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 preconfigured 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 Media Access Control (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.

# 4.1.1. Definition of ma-preconfig-obj

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

The ma-preconfig-obj describes information that needs to be available to the MA in order to bootstrap communication with a Controller. The ma-preconfig-obj consists of the following elements:

ma-preconfig-agent-id:
  An optional UUID uniquely identifying the Measurement Agent.
ma-preconfig-control-tasks:
  An unordered set of Task objects.
ma-preconfig-control-channels:
  An unordered set of Channel objects.
ma-preconfig-control-schedules:
  An unordered set of scheduling objects.
ma-preconfig-device-id:
  An optional identifier for the device.
ma-preconfig-credentials:
  The security credentials used by the Measurement Agent.

# 4.2. 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 preconfigured Controller (specified as a Channel or Channels) may be overridden 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 overridden 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 identifier to the Measurement Agent is mandatory. If the Measurement Agent Identifier was not optionally provided during the preconfiguration, then one must be provided by the Controller during Configuration. Optionally, a Group-ID may also be given that 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. Additional flags control whether the MA-ID or the Group-ID are included in Reports. The reporting of a Group-ID without the MA-ID may allow 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 from 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 an Event is generated that can trigger the suspension of Instruction Schedules. 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 to tolerate continued operation with potentially stale Instruction Information.

While Preconfiguration Information is persistent upon a device reset or power cycle, the persistency of the Configuration Information may be device dependent. Some devices may revert back to their preconfiguration 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.

# 4.2.1. Definition of ma-config-obj

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

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

ma-config-agent-id:
  A UUID uniquely identifying the Measurement Agent.
ma-config-control-tasks:
  An unordered set of Task objects.
ma-config-control-channels:
  An unordered set of Channel objects.
ma-config-control-schedules:
  An unordered set of scheduling objects.
ma-config-credentials:
  The security credentials used by the Measurement Agent.
ma-config-group-id:
  An optional identifier of the group of Measurement Agents this Measurement Agent belongs to.
ma-config-measurement-point:
  An optional identifier for the measurement point indicating where the Measurement Agent is located on a path (see [RFC7398] for further details).
ma-config-report-agent-id:
  An optional flag indicating whether the Agent Identifier (ma‑config‑agent‑id) is included in reports. The default value is true.
ma-config-report-group-id:
  An optional flag indicating whether the Group-ID (ma‑config‑group‑id) is included in reports. The default value is false.
ma-config-report-measurement-point:
  An optional flag indicating whether the measurement point (ma-config-measurement-point) should be included in reports. The default value is false.
ma-config-controller-timeout:
  A timer is started after each successful contact with a Controller. When the timer reaches the controller-timeout (measured in seconds), an Event is raised indicating that connectivity to the Controller has been lost (see ma‑controller‑lost‑obj).

# 4.3. 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 Configuration or Preconfiguration Information). The Tasks are configured in Instruction Task Configurations and included by reference in the Actions of 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 Task including the ability to resolve the Task to an executable and to specify 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 a 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. For example, a single Collector may receive data at three different cycle rates, with 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 extends a configured 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 output data from Tasks to other Schedules.

Measurement Suppression information is used to override 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.

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).

A single Suppression object is able to enable/disable a set of Instruction Tasks that are tagged for Suppression. This enables fine-grained control on which Tasks are suppressed. Suppression of both matching Actions and Measurement Schedules is supported. Support for disabling specific Actions allows malfunctioning or misconfigured Tasks or Actions 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 to be suppressed quickly and effectively. Note that Suppression has no effect on either Controller Tasks or Controller Schedules.

Suppression stops new Tasks from executing. In addition, the Suppression information also supports an additional boolean that is used to select whether ongoing 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 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 communication between the MA and its Controller, this can reduce the data overhead. It also encourages the reuse of the same standard Task Configurations and Reporting Channels to help ensure consistency and reduce errors.

# 4.3.1. Definition of ma-instruction-obj

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

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

ma-instruction-tasks:
  A possibly empty unordered set of Task objects.
ma-instruction-channels:
  A possibly empty unordered set of Channel objects.
ma-instruction-schedules:
  A possibly empty unordered set of Schedule objects.
ma-instruction-suppressions:
  An optional possibly empty unordered set of Suppression objects.

# 4.3.2. Definition of ma-suppression-obj

      object {
          string              ma-suppression-name;
         [ma-event-obj        ma-suppression-start;]
         [ma-event-obj        ma-suppression-end;]
         [string              ma-suppression-match<0..*>;]
         [boolean             ma-suppression-stop-running;]
      } ma-suppression-obj;

The ma-suppression-obj controls the Suppression of Schedules or Actions and consists of the following elements:

ma-suppression-name:
  A name uniquely identifying a Suppression.
ma-suppression-start:
  The optional Event indicating when Suppression starts. If not present, the Suppression starts immediately, i.e., as if the value would be 'immediate'.
ma-suppression-end:
  The optional Event indicating when Suppression ends. If not present, the Suppression does not have a defined end, i.e., the Suppression remains for an indefinite period of time.
ma-suppression-match:
  An optional and possibly empty unordered set of match patterns. The Suppression will apply to all Schedules (and their Actions) that have a matching value in their ma‑schedule‑suppression‑tags and all Actions that have a matching value in their ma‑action‑suppression‑tags. Pattern matching is done using a glob style pattern (see below).
ma-suppression-stop-running:
  An optional boolean indicating whether Suppression will stop any running matching Schedules or Actions. The default value for this boolean is false.

Glob style pattern matching is following POSIX.2 fnmatch() [POSIX.2] without special treatment of file paths:

                *         matches a sequence of characters
                ?         matches a single character
                [seq]     matches any character in seq
                [!seq]    matches any character not in seq

A backslash followed by a character matches the following character. In particular:

                \*        matches *
                \?        matches ?
                \\        matches \

A sequence seq may be a sequence of characters (e.g., [abc]) or a range of characters (e.g., [a-c]).

# 4.4. 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 that 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"
   - "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.

# 4.4.1. Definition of ma-log-obj

      object {
          uuid                ma-log-agent-id;
          datetime            ma-log-event-time;
          int                 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.

# 4.5. 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 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.

# 4.5.1. Definition of ma-capability-obj

      object {
          string                  ma-capability-hardware;
          string                  ma-capability-firmware;
          string                  ma-capability-version;
         [string                  ma-capability-tags<0..*>;]
         [ma-capability-task-obj  ma-capability-tasks<0..*>;]
      } ma-capability-obj;

The ma-capability-obj provides information about the Capabilities of the Measurement Agent and consists of the following elements:

ma-capability-hardware:
  A description of the hardware of the device the Measurement Agent is running on.
ma-capability-firmware:
  A description of the firmware of the device the Measurement Agent is running on.
ma-capability-version:
  The version of the Measurement Agent.
ma-capability-tags:
  An optional unordered set of tags that provide additional information about the Capabilities of the Measurement Agent.
ma-capability-tasks:
  An optional unordered set of capability objects for each supported Task.

# 4.5.2. Definition of ma-capability-task-obj

      object {
          string              ma-capability-task-name;
          ma-registry-obj     ma-capability-task-functions<0..*>;
          string              ma-capability-task-version;
      } ma-capability-task-obj;

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

ma-capability-task-name:
  A name uniquely identifying a Task.
ma-capability-task-functions:
  A possibly empty unordered set of registry entries identifying functions this Task implements.
ma-capability-task-version:
  The version of the Measurement Task.

# 4.5.3. Definition of ma-status-obj

      object {
          uuid                       ma-status-agent-id;
         [uri                        ma-status-device-id;]
          datetime                   ma-status-last-started;
          ma-status-interface-obj    ma-status-interfaces<0..*>;
         [ma-status-schedule-obj     ma-status-schedules<0..*>;]
         [ma-status-suppression-obj  ma-status-suppressions<0..*>;]
      } ma-status-obj;

The ma-status-obj provides Status Information about the Measurement Agent and consists of the following elements:

ma-status-agent-id:
  A uuid uniquely identifying the Measurement Agent.
ma-status-device-id:
  A URI identifying the device.
ma-status-last-started:
  The date and time the Measurement Agent last started.
ma-status-interfaces:
  An unordered set of network interfaces available on the device.
ma-status-schedules:
  An optional unordered set of status objects for each Schedule.
ma-status-suppressions:
  An optional unordered set of status objects for each Suppression.

# 4.5.4. Definition of ma-status-schedule-obj

      object {
          string                  ma-status-schedule-name;
          string                  ma-status-schedule-state;
          int                     ma-status-schedule-storage;
          counter                 ma-status-schedule-invocations;
          counter                 ma-status-schedule-suppressions;
          counter                 ma-status-schedule-overlaps;
          counter                 ma-status-schedule-failures;
          datetime                ma-status-schedule-last-invocation;
         [ma-status-action-obj    ma-status-schedule-actions<0..*>;]
      } ma-status-schedule-obj;

The ma-status-schedule-obj provides Status Information about the status of a Schedule and consists of the following elements:

ma-status-schedule-name:
  The name of the Schedule this status object refers to.
ma-status-schedule-state:
  The state of the Schedule. The value 'enabled' indicates that the Schedule is currently enabled. The value 'suppressed' indicates that the Schedule is currently suppressed. The value 'disabled' indicates that the Schedule is currently disabled. The value 'running' indicates that the Schedule is currently running.
ma-status-schedule-storage:
  The amount of secondary storage (e.g., allocated in a file system) holding temporary data allocated to the Schedule in bytes. This object reports the amount of allocated physical storage and not the storage used by logical data records. Data models should use a 64-bit integer type.
ma-status-schedule-invocations
  Number of invocations of this Schedule. This counter does not include suppressed invocations or invocations that were prevented due to an overlap with a previous invocation of this Schedule.
ma-status-schedule-suppressions
  Number of suppressed executions of this Schedule.
ma-status-schedule-overlaps
  Number of executions prevented due to overlaps with a previous invocation of this Schedule.
ma-status-schedule-failures
  Number of failed executions of this Schedule. A failed execution is an execution where at least one Action failed.
ma-status-schedule-last-invocation:
  The date and time of the last invocation of this Schedule.
ma-status-schedule-actions:
  An optional ordered list of status objects for each Action of the Schedule.

# 4.5.5. Definition of ma-status-action-obj

      object {
          string              ma-status-action-name;
          string              ma-status-action-state;
          int                 ma-status-action-storage;
          counter             ma-status-action-invocations;
          counter             ma-status-action-suppressions;
          counter             ma-status-action-overlaps;
          counter             ma-status-action-failures;
          datetime            ma-status-action-last-invocation;
          datetime            ma-status-action-last-completion;
          int                 ma-status-action-last-status;
          string              ma-status-action-last-message;
          datetime            ma-status-action-last-failed-completion;
          int                 ma-status-action-last-failed-status;
          string              ma-status-action-last-failed-message;
      } ma-status-action-obj;

The ma-status-action-obj provides Status Information about an Action of a Schedule and consists of the following elements:

ma-status-action-name:
  The name of the Action of a Schedule this status object refers to.
ma-status-action-state:
  The state of the Action. The value 'enabled' indicates that the Action is currently enabled. The value 'suppressed' indicates that the Action is currently suppressed. The value 'disabled' indicates that the Action is currently disabled. The value 'running' indicates that the Action is currently running.
ma-status-action-storage:
  The amount of secondary storage (e.g., allocated in a file system) holding temporary data allocated to the Action in bytes. This object reports the amount of allocated physical storage and not the storage used by logical data records. Data models should use a 64-bit integer type.
ma-status-action-invocations
  Number of invocations of this Action. This counter does not include suppressed invocations or invocations that were prevented due to an overlap with a previous invocation of this Action.
ma-status-action-suppressions
  Number of suppressed executions of this Action.
ma-status-action-overlaps
  Number of executions prevented due to overlaps with a previous invocation of this Action.
ma-status-action-failures
  Number of failed executions of this Action.
ma-status-action-last-invocation:
  The date and time of the last invocation of this Action.
ma-status-action-last-completion:
  The date and time of the last completion of this Action.
ma-status-action-last-status:
  The status code returned by the last execution of this Action.
ma-status-action-last-message:
  The status message produced by the last execution of this Action.
ma-status-action-last-failed-completion:
  The date and time of the last failed completion of this Action.
ma-status-action-last-failed-status:
  The status code returned by the last failed execution of this Action.
ma-status-action-last-failed-message:
  The status message produced by the last failed execution of this Action.

# 4.5.6. Definition of ma-status-suppression-obj

      object {
          string                  ma-status-suppression-name;
          string                  ma-status-suppression-state;
      } ma-status-suppression-obj;

The ma-status-suppression-obj provides Status Information about the status of a Suppression and consists of the following elements:

ma-status-suppression-name:
  The name of the Suppression this status object refers to.
ma-status-suppression-state:
  The state of the Suppression. The value 'enabled' indicates that the Suppression is currently enabled. The value 'active' indicates that the Suppression is currently active. The value 'disabled' indicates that the Suppression is currently disabled.

# 4.5.7. Definition of ma-status-interface-obj

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

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

ma-status-interface-name:
  A name uniquely identifying a network interface.
ma-status-interface-type:
  The type of the network interface.
ma-status-interface-speed:
  An optional indication of the speed of the interface (measured in bits per second).
ma-status-interface-link-layer-address:
  An optional link-layer address of the interface.
ma-status-interface-ip-addresses:
  An optional ordered list of IP addresses assigned to the interface.
ma-status-interface-gateways:
  An optional ordered list of gateways assigned to the interface.
ma-status-interface-dns-servers:
  An optional ordered list of DNS servers assigned to the interface.

# 4.6. Reporting Information

At a point in time specified by a Schedule, the MA will execute 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 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 Collectors.

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 Identifier 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 Action 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 Identifier 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. It is generally suggested that implementations running out of storage stop executing new Measurement Tasks and retain old measurement data.

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 Action. The Action 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 utilization or interface speed.

Whereas 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.

# 4.6.1. Definition of ma-report-obj

      object {
          datetime              ma-report-date;
         [uuid                  ma-report-agent-id;]
         [string                ma-report-group-id;]
         [string                ma-report-measurement-point;]
         [ma-report-result-obj  ma-report-results<0..*>;]
      } ma-report-obj;

The ma-report-obj provides the metadata 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-measurement-point:
  An optional identifier for the measurement point indicating where the Measurement Agent is located on a path (see [RFC7398] for further details).
ma-report-results:
  An optional and possibly empty unordered set of result objects.

# 4.6.2. Definition of ma-report-result-obj

      object {
          string                  ma-report-result-schedule-name;
          string                  ma-report-result-action-name;
          string                  ma-report-result-task-name;
         [ma-option-obj           ma-report-result-options<0..*>;]
         [string                  ma-report-result-tags<0..*>;]
          datetime                ma-report-result-event-time;
          datetime                ma-report-result-start-time;
         [datetime                ma-report-result-end-time;]
         [string                  ma-report-result-cycle-number;]
          int                     ma-report-result-status;
         [ma-report-conflict-obj  ma-report-result-conflicts<0..*>;]
         [ma-report-table-obj     ma-report-result-tables<0..*>;]
      } ma-report-result-obj;

The ma-report-result-obj provides the metadata of a result report of a single executed Action. It consists of the following elements:

ma-report-result-schedule-name:
  The name of the Schedule that produced the result.
ma-report-result-action-name:
  The name of the Action in the Schedule that produced the result.
ma-report-result-task-name:
  The name of the Task that produced the result.
ma-report-result-options:
  An optional ordered joined list of options provided by the Task object and the Action object when the Action was started.
ma-report-result-tags:
  An optional unordered set of tags. This is the joined set of tags provided by the Task object, Action object, and Schedule object when the Action was started.
ma-report-result-event-time:
  The date and time of the Event that triggered the Schedule of the Action that produced the reported result values. The date and time does not include any added randomization.
ma-report-result-start-time:
  The date and time of the start of the Action that produced the reported result values.
ma-report-result-end-time:
  An optional date and time indicating when the Action finished.
ma-report-result-cycle-number:
  An optional cycle number derived from ma-report-result-event-time. It is the time closest to ma‑report‑result‑event‑time that is a multiple of the ma‑event‑cycle‑interval of the Event that triggered the execution of the Schedule. The value is only present in an ma‑report‑result‑obj if the Event that triggered the execution of the Schedule has a defined ma‑event‑cycle‑interval. The cycle number is represented in the format YYYYMMDD.HHMMSS where YYYY represents the year, MM the month (1..12), DD the day of the months (01..31), HH the hour (00..23), MM the minute (00..59), and SS the second (00..59). The cycle number is using Coordinated Universal Time (UTC).
ma-report-result-status:
  The status code returned by the execution of the Action.
ma-report-result-conflicts:
  A possibly empty set of conflict Actions that might have impacted the measurement results being reported.
ma-report-result-tables:
  An optional and possibly empty unordered set of result tables.

# 4.6.3. Definition of ma-report-conflict-obj

      object {
          string  ma-report-conflict-schedule-name;
          string  ma-report-conflict-action-name;
          string  ma-report-conflict-task-name;
      } ma-report-conflict-obj;

The ma-report-conflict-obj provides the information about a conflicting Action that might have impacted the measurement results. It consists of the following elements:

ma-report-result-schedule-name:
  The name of the Schedule that may have impacted the result.
ma-report-result-action-name:
  The name of the Action in the Schedule that may have impacted the result.
ma-report-result-task-name:
  The name of the Task that may have impacted the result.

# 4.6.4. Definition of ma-report-table-obj

      object {
         [ma-registry-obj     ma-report-table-functions<0..*>;]
         [string]             ma-report-table-column-labels<0..*>;]
         [ma-report-row-obj   ma-report-table-rows<0..*>;]
      } ma-report-table-obj;

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

ma-report-table-functions:
  An optional and possibly empty unordered set of registry entries identifying the functions for which results are reported.
ma-report-table-column-labels:
  An optional and possibly empty ordered list of column labels.
ma-report-table-rows:
  A possibly empty ordered list of result rows.

# 4.6.5. Definition of ma-report-row-obj

      object {
          data                ma-report-row-values<0..*>;
      } ma-report-row-obj;

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

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

# 4.7. Common Objects: Schedules

A Schedule specifies the execution of a single or repeated series of Actions. An Action extends a configured Task with additional specific parameters. Each Schedule contains basically two elements: an ordered list of Actions to be executed and an Event object triggering the execution of the Schedule. The Schedule states what Actions to run (with what configuration) and when to run the Actions. A Schedule may optionally have an Event that stops the execution of the Schedule or a maximum duration after which a Schedule is stopped.

Multiple Actions contained as an ordered 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 contained 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 prioritize 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 results. An Action receiving 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 interface, but it also outputs emergency conditions via an alarm Reporting Task in a different Schedule communicating immediately over a General Packet Radio Service (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. The Information Model, however, reports the storage allocated to Schedules and Actions so that storage usage can be monitored. Furthermore, it is recommended that MA implementations by default retain old data and stop the execution of new Measurement Tasks if the MA runs out of storage capacity.

When specifying the Task to execute within the Schedule, i.e., creating an Action, it is possible to add to the 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 as Option parameters of the Action in the Schedule. A single Task's 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 (in either the Task Configuration, the Action, or both) is not standardized 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 Action and the Task Configuration, the Action 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.

Schedules and Actions may optionally also be given tags that are included in result reports sent to a Collector. In addition, Schedules can be given Suppression tags that may be used to select Schedules and Actions for Suppression.

# 4.7.1. Definition of ma-schedule-obj

      object {
          string              ma-schedule-name;
          ma-event-obj        ma-schedule-start;
         [ma-event-obj        ma-schedule-end;]
         [int                 ma-schedule-duration;]
          ma-action-obj       ma-schedule-actions<0..*>;
          string              ma-schedule-execution-mode;
         [string              ma-schedule-tags<0..*>;]
         [string              ma-schedule-suppression-tags<0..*>;]
      } 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-start:
  An Event object indicating when the Schedule starts.
ma-schedule-end:
  An optional Event object controlling the forceful termination of scheduled Actions. When the Event occurs, all Actions of the Schedule will be forced to terminate gracefully.
ma-schedule-duration:
  An optional duration in seconds for the Schedule. All Actions of the Schedule will be forced to terminate gracefully after the duration number of seconds past the start of the Schedule.
ma-schedule-actions:
  A possibly empty ordered list of Actions to invoke when the Schedule starts.
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). The default execution mode is pipelined.
ma-schedule-tags:
  An optional unordered set of tags that are reported together with the measurement results to a Collector.
ma-schedule-suppression-tags:
  An optional unordered set of Suppression tags that are used to select Schedules to be suppressed.

# 4.7.2. Definition of ma-action-obj

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

The ma-action-obj models a Task together with its Schedule-specific Task Options and Destination Schedules. It consists of the following elements:

ma-action-name:
  A name uniquely identifying an Action of a scheduling object.
ma-action-config-task-name:
  A name identifying the configured Task to be invoked by the Action.
ma-action-task-options:
  An optional and possibly empty ordered list of options (name-value pairs) that are passed to the Task by appending them to the options configured for the Task object.
ma-action-destinations:
  An optional and possibly empty unordered set of names of Destination Schedules that consume output produced by this Action.
ma-action-tags:
  An optional unordered set of tags that are reported together with the measurement results to a Collector.
ma-action-suppression-tags:
  An optional unordered set of Suppression tags that are used to select Actions to be suppressed.

# 4.8. Common Objects: Channels

A Channel defines a bidirectional communication mechanism 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 a 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 Fully Qualified Domain Name (FQDN) in the URL, or it can be the certificate of the Certification Authority that was used to issue the certificate for the FQDN of the target URL (which will be retrieved later on using a communication protocol such as Transport Layer Security (TLS)). In order to establish a secure Channel, the MA will use its own security credentials (in the Configuration Information) and the given credentials for the individual Channel endpoint.

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.

# 4.8.1. 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 IP protocol stack will select a suitable interface.

# 4.9. Common Objects: Task Configurations

Conceptually, each Task Configuration defines the parameters of a Task that the 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 may 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 such as the to-be-created IPPM registry described in [IPPM-REG].

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, defined as an Option, to indicate whether to send a report without measurement results if there is no measurement result data pending to be transferred to the Collector. In addition, many Tasks will receive (as a parameter) information about which interface to use.

In addition, the Task Configuration may optionally also be given tags that can carry 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.

# 4.9.1. Definition of ma-task-obj

      object {
          string              ma-task-name;
          ma-registry-obj     ma-task-functions<0..*>;
         [ma-option-obj       ma-task-options<0..*>;]
         [string              ma-task-tags<0..*>;]
      } ma-task-obj;

The ma-task-obj defines a configured Task that can be invoked as part of an Action. A configured Task can be referenced by its name, and it contains a possibly empty set of URIs to link to registry entries. Options allow the configuration of Task parameters (in the form of name-value pairs). The ma-task-obj consists of the following elements:

ma-task-name:
  A name uniquely identifying a configured Task object.
ma-task-functions:
  A possibly empty unordered set of registry entries identifying the functions of the configured Task.
ma-task-options:
  An optional and possibly empty ordered list of options (name-value pairs) that are passed to the configured Task.
ma-task-tags:
  An optional unordered set of tags that are reported together with the measurement results to a Collector.

# 4.9.2. 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.
ma-option-value:
  The optional value of the option.

The ma-option-obj is used to define Task Configuration Options. Task Configuration Options are generally Task specific. For Tasks associated with an entry in a registry, the registry may define well-known option names (e.g., the so-called parameters in the to-be-created IPPM metric registry described in [IPPM-REG]). Control and Reporting Tasks need to know the Channel they are going to use. The common option name for specifying the Channel is "channel" where the option's value refers to the name of an ma-channel-obj.

# 4.10. Common Objects: Registry Information

Tasks and Actions can be associated with entries in a registry. A registry object refers to an entry in a registry (identified by a URI), and it may define a set of roles.

# 4.10.1. Definition of ma-registry-obj

      object {
          uri                 ma-registry-uri;
         [string              ma-registry-role<0..*>;]
      } ma-registry-obj;

The ma-registry-obj refers to an entry of a registry, and it defines the associated role(s). The ma-registry-obj consists of the following elements:

ma-registry-uri:
  A URI identifying an entry in a registry.
ma-registry-role:
  An optional and possibly empty unordered set of roles for the identified registry entry.

# 4.11. Common Objects: Event Information

The Event information object used throughout the Information Models can initially take one of several different forms. Additional forms may be defined later in order to bind the execution of Schedules to additional Events. The initially defined Event forms are:

1. Periodic Timing: Emits multiple Events periodically according to an interval time defined in seconds
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)
6. Controller Lost: Emits an Event when connectivity to the Controller has been lost
7. Controller Connected: Emits an Event when connectivity to the Controller has been established or re-established

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 seconds over which the start of the Task is delayed from the starting times specified by the Event 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.

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].

# 4.11.1. Definition of ma-event-obj

      object {
         string               ma-event-name;
         union {
             ma-periodic-obj             ma-event-periodic;
             ma-calendar-obj             ma-event-calendar;
             ma-one-off-obj              ma-event-one-off;
             ma-immediate-obj            ma-event-immediate;
             ma-startup-obj              ma-event-startup;
             ma-controller-lost-obj      ma-event-controller-lost;
             ma-controller-connected-obj ma-event-controller-connected;
         }
         [int                 ma-event-random-spread;]
         [int                 ma-event-cycle-interval;]
      } ma-event-obj;

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

ma-event-name:
  The name uniquely identifies an Event object. Schedules refer to Event objects by this name.
ma-event-periodic:
  The ma-event-periodic is present for periodic timing objects.
ma-event-calendar:
  The ma-event-calendar is present for calendar timing objects.
ma-event-one-off:
  The ma-event-one-off is present for one-off timing objects.
ma-event-immediate:
  The ma-event-immediate is present for immediate Event objects.
ma-event-startup:
  The ma-event-startup is present for startup Event objects.
ma-event-controller-lost:
  The ma-event-controller-lost is present for connectivity to Controller lost Event objects.
ma-event-controller-connected:
  The ma-event-controller-connected is present for connectivity to Controller established Event objects.
ma-event-random-spread:
  The optional ma-event-random-spread adds a random delay defined in seconds to the Event object. No random delay is added if ma‑event‑random‑spread does not exist.
ma-event-cycle-interval:
  The optional ma-event-cycle-interval defines the duration of the time interval in seconds that is used to calculate cycle numbers. No cycle number is calculated if ma‑event‑cycle‑interval does not exist.

# 4.11.2. 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 seconds between two consecutive starts of Tasks.

# 4.11.3. Definition of ma-calendar-obj

Calendar timing supports the routine execution of Schedules at specific times and/or on specific dates. It can support more flexible timing than periodic timing since the execution of Schedules does not have to be uniformly spaced. For example, a calendar timing could support the execution of a Measurement Task every hour between 6 pm 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 time zone 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 that may be in an unknown time zone or to roam between different time zones (but know their own time zone 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 month (1-31) on which Tasks scheduled using this object are started. The wildcard * means all days of a month. 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 minutes.
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 time zone offset in minutes. If not present, it defaults to the system's local time zone.

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

# 4.11.4. 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.

# 4.11.5. Definition of ma-immediate-obj

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

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

# 4.11.6. Definition of ma-startup-obj

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

The ma-startup-obj Event object has no further information elements. Schedules or Suppressions using an ma-startup-obj are started at MA initialization time.

# 4.11.7. Definition of ma-controller-lost-obj

      object {
                              // empty
      } ma-controller-lost-obj;

The ma-controller-lost-obj Event object has no further information elements. The ma-controller-lost-obj indicates that connectivity to the Controller has been lost. This is determined by a timer started after each successful contact with a Controller. When the timer reaches the controller-timeout (measured in seconds), a ma‑controller‑lost‑obj Event is generated. This Event may be used to start a Suppression.

# 4.11.8. Definition of ma-controller-connected-obj

      object {
                              // empty
      } ma-controller-connected-obj;

The ma-controller-connected-obj Event object has no further information elements. The ma-controller-connected-obj indicates that connectivity to the Controller has been established again after it was lost. This Event may be used to end a Suppression.

# 5. Example Execution

The example execution has two Event sources, E1 and E2, and three Schedules, S1, S2, and S3. The Schedule S3 is started by Events of Event source E2 while the Schedules S1 and S2 are both started by Events of the Event source E1. The Schedules S1 and S2 have two Actions each, and Schedule S3 has a single Action. The Event source E2 has no randomization while the Event source E1 has the randomization r.

Figure 2 shows a possible timeline of an execution. The time T is progressing downwards. The dotted vertical line indicates progress of time while a dotted horizontal line indicates which Schedules are triggered by an Event. Lines of tildes indicate data flowing from an Action to another Schedule. Actions within a Schedule are named A1, A2, etc.

      E2    E1   T           S1           S2            S3
                         sequential    parallel     pipelined
                 :
              e0 +
                 :
                 :
            e0+r + .......... + .......... ++
                 :            | A1      A1 || A2
                 :            +            |+ ~~~~~~~>
                 :            | A2         |
                 :            |            + ~~~~~~~~>
                 :            + ~~~~~~~~~~~~~~~~~~~~~>
                 :
                 :
              e1 +
                 :
            e1+r + .......... + .......... ++
                 :            | A1      A1 ||
                 :            |            +|~~~~~~~>
                 :            |             | A2
                 :            +             +~~~~~~~>
                 :            | A2
                 :            + ~~~~~~~~~~~~~~~~~~~~>
       e0        + ................................... +
                 :                                     | A1
              e3 +                                     |
            e3+r + .......... + .......... ++          |
                 :            | A1      A1 || A2       |
                 :            +            ++ ~~~~~~>  |
                 :            | A2                     +
                 :            + ~~~~~~~~~~~~~~~~~~~~>
                 V

Figure 2: Example Execution

Note that implementations must handle possible concurrency issues. In the example execution, Action A1 of Schedule S3 is consuming the data that has been forwarded to Schedule S3 while additional data is arriving from Action A2 of Schedule S2.

# 6. IANA Considerations

This document does not require any IANA actions.

# 7. 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 preconfigure the MA must also be secure to protect unauthorized parties from modifying Preconfiguration Information. These mechanisms are important to ensure that the MA cannot be hijacked, for example, to participate in a distributed denial-of-service 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 may, 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. Implementations and deployments should also be careful about exposing device-ids when this is not strictly needed.

An implementation of this Information Model should support all the security and privacy requirements associated with the LMAP Framework [RFC7594]. In addition, users of this Information Model are advised to choose identifiers for Group-IDs, tags, or names of Information Model objects (e.g., configured Tasks, Schedules, or Actions) that do not reveal any sensitive information to people authorized to process measurement results but who are not authorized to know details about the Measurement Agents that were used to perform the measurement.

# 8. References

# 8.1. Normative References

[ISO.10646] | International Organization for Standardization, "Information Technology - Universal Coded Character Set (UCS)", ISO Standard 10646:2014, September 2014.
[POSIX.2] | The Open Group, "Standard for Information Technology - Portable Operating System Interface (POSIX(R)) Base Specifications, Issue 7", IEEE Standard 1003.1, 2016 Edition, DOI, 10.1109/IEEESTD.2016.7582338, September 2016.
[RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3339] | Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002.
[RFC3986] | Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005.
[RFC4122] | Leach, P., Mealling, M. and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, July 2005.
[RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.

# 8.2. Informative References

[IPPM-REG] | Bagnulo, M., Claise, B., Eardley, P., Morton, A. and A. Akhter, "Registry for Performance Metrics", Work in Progress, draft-ietf-ippm-metric-registry-12, June 2017.
[RFC3444] | Pras, A. and J. Schoenwaelder, "On the Difference between Information Models and Data Models", RFC 3444, DOI 10.17487/RFC3444, January 2003.
[RFC7398] | Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P. and A. Morton, "A Reference Path and Measurement Points for Large-Scale Measurement of Broadband Performance", RFC 7398, DOI 10.17487/RFC7398, February 2015.
[RFC7536] | Linsner, M., Eardley, P., Burbridge, T. and F. Sorensen, "Large-Scale Broadband Measurement Use Cases", RFC 7536, DOI 10.17487/RFC7536, May 2015.
[RFC7594] | Eardley, P., Morton, A., Bagnulo, M., Burbridge, T., Aitken, P. and A. Akhter, "A Framework for Large-Scale Measurement of Broadband Performance (LMAP)", RFC 7594, DOI 10.17487/RFC7594, September 2015.
[RFC8194] | Schoenwaelder, J. and V. Bajpai, "A YANG Data Model for LMAP Measurement Agents", RFC 8194, DOI 10.17487/RFC8194, August 2017.

# Acknowledgements

Several people contributed to this specification by reviewing early draft versions and actively participating in the LMAP Working Group (apologies to those unintentionally omitted): Vaibhav Bajpai, Michael Bugenhagen, Timothy Carey, Alissa Cooper, Kenneth Ko, Al Morton, Dan Romascanu, Henning Schulzrinne, Andrea Soppera, Barbara Stark, and Jason Weil.

Marcelo Bagnulo, Trevor Burbridge, Philip Eardley, and Juergen Schoenwaelder worked in part on the Leone research project, which received funding from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement number 317647.

Juergen Schoenwaelder was partly funded by Flamingo, a Network of Excellence project (ICT-318488) supported by the European Commission under its Seventh Framework Programme.

# Authors' Addresses