Network Working Group P. Eardley Internet-Draft BT Intended status: Standards Track A. Morton Expires: October 14, 2013 AT&T Labs M. Bagnulo UC3M T. Burbridge BT April 12, 2013 Terminology for Large-Scale Measurement of Broadband Performance (LMAP) Platforms draft-eardley-lmap-terminology-00 Abstract This documents defines terminology for Large Scale Measurement Platforms. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on October 14, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Eardley, et al. Expires October 14, 2013 [Page 1] Internet-Draft LMAP Terminology April 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. LMAP Terminology . . . . . . . . . . . . . . . . . . . . . . 4 4. Commentary and notes . . . . . . . . . . . . . . . . . . . . 6 5. Security considerations . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. Informative References . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction This document defines terminology for LMAP (in Section 3). Since 'raw' terminology is reader-unfriendly, Section 2 provides an initial idea of the terminology by explaining how LMAP works whilst using the terms. Section 4 provides some commentary on the terminology, including a comparison with that in [RFC2330]. Please note that defined terms are capitalized. 2. Summary A Measurement Task is an act that yields a single Measurement Result. An Active Measurement Task involves a Measurement Agent injecting test packet(s) into the network destined for another Measurement Agent and measuring some performance or reliability parameter associated with the transfer. The generic version of the Measurement Task is the Measurement Method; in other words the Measurement Task is the instantiation of the Measurement Method at a specific time and place. For example, a Measurement Method might be the injection of a UDP packet by one Measurement Agent destined for another Measurement Agent, which immediately reflects the UDP packet back to the first Measurement Agent, which measures the round trip latency. The associated Measurement Task might be: the injection of a UDP packet by the Measurement Agent at 138.246.23.109 destined for the Measurement Agent at 138.145.75.32 at UTC 13:01 and 58.6 seconds on 2013-06-15, with the second Measurement Agent immediately reflecting the UDP packet back to the source, which measures the associated round trip latency (using a second timestamp associated with arrival). Eardley, et al. Expires October 14, 2013 [Page 2] Internet-Draft LMAP Terminology April 2013 A Metric is a parameter of interest that is related to the performance and reliability of the Internet. For example, "UDP latency". Typically the value of a Metric is assessed as simply the average of several Measurement Results. However a Derived Metric consists of some combination of various Measurement Results. For example, the delay variation of a path can be assessed by subtracting two values of one-way delay [RFC3393], or the bulk transport capacity might be assessed by combining several different parameters as suggested in [I-D.mathis-ippm-model-based-metrics]. How and when to perform the Measurement Task and report the Measurement Result is defined by the Instruction, which the Controller sends to the Measurement Agent. Whilst the Instruction may define a single Measurement Task, more typically it defines a series of Measurement Tasks, all based on the same Measurement Method and carried out at regular times according to a Measurement Schedule. The Measurement Result of the former is likely to be reported immediately, whilst Measurement Results of the latter will be sent at regular time intervals, as defined by the Report Schedule. The Instruction consists of: o The Measurement Method: typically this is defined by a reference in a well-known registry (for example, 'how to measure UDP latency') o The configuration of parameters left open by the Measurement Method (for example, the addresses of the two Measurement Agents) o The Measurement Schedule (for example, start at 0400 UTC, repeat every 500 ms, end at 0403 UTC) o Any environmental constraints (for example, do not perform the Measurement Task if there is cross-traffic) o The above bullets effectively define a series of Measurement Tasks o The definition of the Report. Typically the Report includes every single Measurement Result (since the last Report), but it may instead be a statistic (such as their average). Typically the Report also includes other relevant information, for example an 'echo' of the Measurement Method, configuration parameters and schedule. o The configuration of parameters associated with the Report (for example, the address of the Collector to which the Report is sent) o The Report Schedule (for example, send once a day at 01:00 hours) Eardley, et al. Expires October 14, 2013 [Page 3] Internet-Draft LMAP Terminology April 2013 The Control Protocol and Report Protocol define the delivery of the Instruction and the Report (respectively); they consist of a Data Model (the semantics and structure of the information, in a particular language such as JSON or YANG) and a transport protocol (such as HTTP or NETCONF). 3. LMAP Terminology Active Measurement Method (Task): A type of Measurement Method (Task) that involves two Measurement Agents, where one Measurement Agent injects test packet(s) into the network destined for another Measurement Agent and which involves one of the Measurement Agents measuring some performance or reliability parameter associated with the transfer of the packet(s). Collector: A function that receives a Report from a Complete Measurement Agent. Colloquially, a Collector is a physical device that performs this function. Complete Measurement Agent (Complete-MA): A type of Measurement Agent that additionally includes functionality that receives an Instruction from a Controller and reports Results to a Collector Controller: A function that provides a Complete-MA with an Instruction. Colloquially, a Controller is a physical device that performs this function. Control Protocol: The definition of how the Instruction is delivered from a Controller to a Complete-MA; a Data Model plus a transport protocol. Data Model: The implementation of an Information Model in a particular data modelling language. Derived Metric: A Metric that is a combination of other Metrics, and/ or a combination of the same Metric measured over different parts of the network, or at different times. Information Model: The abstract definition of either the Instruction or the Report; the semantics of the fields and their arrangement (the order they appear in and any hierarchy). Instruction: The description of Measurement Tasks to perform and the details of the Report to send; a specific instance of the Data Model. The Instruction is sent by a Controller to a Complete-MA. Eardley, et al. Expires October 14, 2013 [Page 4] Internet-Draft LMAP Terminology April 2013 Measurement Agent (MA): The function that performs a Measurement Task. Colloquially, a Measurement Agent is a physical device that performs this function. Measurement Method: The process for assessing the value of a Metric; the process of measuring some performance or reliability parameter; the generalisation of a Measurement Task. Measurement Result: The output of a single Measurement Task (the value obtained for the parameter of interest, or metric) Measurement Schedule: the schedule for performing a series of Measurement Tasks Measurement Task: The act that yields a single Measurement Result; the act consisting of the (single) operation of the Measurement Method at a particular time and with all its parameters set to specific values Metric: The quantity related to the performance and reliability of the Internet that we'd like to know the value of, and that is carefully specified. Passive Measurement Method (Task): A Measurement Method (Task) in which a Measurement Agent observes existing traffic at a specific measurement point, but does not inject test packet(s). Remote Measurement Agent (Remote-MA): A type of Measurement Agent that does not receive an Instruction from a Controller and does not send a Report to a Collector; it may receive control messages and test packet(s) from a Complete-MA and may reply to the Complete-MA, as defined by the Measurement Method. Report: The Measurement Results and other associated information (as defined by the Instruction); a specific instance of the Data Model. The Report is sent by a Complete-MA to a Collector Report Protocol: The definition of how the Report is delivered from a Complete-MA to a Collector; a Data Model plus a transport protocol. Report Schedule: the schedule for sending a series of Reports to a Collector. Eardley, et al. Expires October 14, 2013 [Page 5] Internet-Draft LMAP Terminology April 2013 4. Commentary and notes To avoid confusion the word 'Measurement' is only used as an adjective. It is worth explaining how the terms defined here compare with those in [RFC2330], "Framework for IP Performance Metrics". The definition of Metric is taken from RFC2330. The definition of Measurement Method is (we believe) equivalent in RFC2330's terms to a measurement methodology for a singleton metric. A set of Measurement Tasks defined by a Measurement Schedule relates to RFC2330's concept of a sample metric. If a Measurement Method is used multiple times under identical or similar conditions, it should result in a consistent value for the Metric. A Measurement Method may be a more specific version of another Measurement Method. For example, [I-D.bagnulo-ippm-new-registry-independent] defines UDP latency as a round trip delay [RFC2681] with the packet type set to UDP. A registry, as proposed in [I-D.bagnulo-ippm-new-registry-independent], would be a registry of Measurement Methods and their associated Metrics. A Passive Measurement Method (Task) involves only one MA, which therefore must be a Complete-MA; for example, it measures the mix of applications. An Active Measurement Method (Task) involves another MA (typically a Remote-MA). It is possible that some Active Measurement Methods (Tasks) involve more than two MAs; for example, to measure 'latency under load' test traffic may be sent between two MAs whilst a third MA generates the load (cross-traffic). In these circumstances the definition of Active Measurement Method (Task) may need a small adjustment. This is for later study. The WG makes the assumption that a Complete-MA receives Instruction from only a single Controller at any point in time (however it may Report to more than one Collector). By definition a Remote-MA does not interact with a Controller or Collector. A Remote-MA will typically respond to the test packet(s) from the Complete-MA. For example, it may echo a UDP packet, or measure the amount of loss of the test packets and then send the Measurement Results to the Complete-MA. The MA is implemented either in specialised hardware or as code on general purpose devices like a PC, tablet or smartphone. Note that a Remote-MA may not have specific LMAP or IPPM functionality. For Eardley, et al. Expires October 14, 2013 [Page 6] Internet-Draft LMAP Terminology April 2013 example, to assess DNS response time a Complete-MA sends DNS requests to a standard DNS server. A Controller can send an Instruction for immediate action, containing a one-off Measurement Task. This is in addition to the more typical scenario of a series of Measurement Tasks carried out on a regular schedule, with the Measurement Results reported periodically. It may be sensible for an Instruction to be able to refer to more than one Measurement Method. This is for further study. The right set of Information Models is for further study - for example, perhaps there should be three Information Models, with one containing all the scheduling information. Also, note that different fields of the Information Models may be relevant for different Measurement Methods. The Control Protocol defines the Data Model and so effectively defines the Instruction. The Instruction includes: the Measurement Method; values for the parameters that the Measurement Method leaves open (configuration); when to perform the Measurement Tasks (the Measurement Schedule); any environmental conditions (such as "don't perform the Measurement Task if there is end user traffic present"); the Report Protocol, which includes its Data Model; when to send a Report (the Report Schedule); where to send the Report (the address of the Collector) and values for any other parameters that the Report Protocol leaves open (configuration). This is for discussion. Typically the Report includes every single Measurement Result, but it may instead be a statistic (such as their average). The latter may be useful when the bandwidth between the MA and Collector is severely constrained and/or the full set of Measurement Results provides little extra information. The Report includes: the Measurement Results (or statistic based on them); the details of the Measurement Tasks (essentially a copy of much of the Instruction, for example the Measurement Method, the configuration parameters and the time at which each Measurement Result was obtained); and other relevant information known by the Complete-MA (such as the line's speed, the version of the MA, and the amount of cross-traffic during the measurement). Again this is very much for discussion. A proposal for a Control Protocol based on HTTP is currently under development. There are already Internet drafts describing a Control Protocol based on NETCONF and a Report Protocol based on IPFIX. Eardley, et al. Expires October 14, 2013 [Page 7] Internet-Draft LMAP Terminology April 2013 The Broadband Forum defines a Management Server [http:// datatracker.ietf.org/liaison/1243/]: "Manages and configures a physical device or network element. Examples include a TR-069 ACS (Auto-Configuration Server), or an EMS (Element Management System)." At the moment we assume that the Broadband Forum will specify this function and so assume it is out of scope of LMAP. Such an initialisation function seems essential for a large-scale measurement system. There must be some automated way to associate a complete-MA to its Controller and Collector, including authentication credentials, to re-arrange such associations over time, and to pull the plug on rogue MAs. 5. Security considerations There are no security considerations needed in a memo that only defines terminology. 6. IANA Considerations There are no IANA considerations in this memo. 7. Acknowledgments 8. Informative References [I-D.bagnulo-ippm-new-registry-independent] Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and A. Morton, "A registry for commonly used metrics. Independent registries", draft-bagnulo-ippm-new-registry- independent-00 (work in progress), January 2013. [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998. [I-D.mathis-ippm-model-based-metrics] Mathis, M. and A. Morton, "Model Based Internet Performance Metrics", draft-mathis-ippm-model-based- metrics-01 (work in progress), February 2013. [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681, September 1999. [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, November 2002. Eardley, et al. Expires October 14, 2013 [Page 8] Internet-Draft LMAP Terminology April 2013 Authors' Addresses Phil Eardley British Telecom Adastral Park, Martlesham Heath IPswitch ENGLAND Email: philip.eardley@bt.com Al Morton AT&T Labs 200 Laurel Avenue South Middletown, NJ USA Email: acmorton@att.com Marcelo Bagnulo Universidad Carlos III de Madrid Av. Universidad 30 Leganes, Madrid 28911 SPAIN Phone: 34 91 6249500 Email: marcelo@it.uc3m.es URI: http://www.it.uc3m.es Trevor Burbridge British Telecom Adastral Park, Martlesham Heath IPswitch ENGLAND Email: trevor.burbridge@bt.com Eardley, et al. Expires October 14, 2013 [Page 9]