--- 1/draft-ietf-ippm-active-passive-01.txt 2015-10-19 11:15:15.686608861 -0700 +++ 2/draft-ietf-ippm-active-passive-02.txt 2015-10-19 11:15:15.718609635 -0700 @@ -1,19 +1,19 @@ Network Working Group A. Morton Internet-Draft AT&T Labs -Intended status: Informational September 6, 2015 -Expires: March 9, 2016 +Intended status: Informational October 19, 2015 +Expires: April 21, 2016 Active and Passive Metrics and Methods (and everything in-between, or Hybrid) - draft-ietf-ippm-active-passive-01 + draft-ietf-ippm-active-passive-02 Abstract This memo provides clear definitions for Active and Passive performance assessment. The construction of Metrics and Methods can be described as Active or Passive. Some methods may use a subset of both active and passive attributes, and we refer to these as Hybrid Methods. Status of This Memo @@ -24,21 +24,21 @@ 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 March 9, 2016. + This Internet-Draft will expire on April 21, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -51,35 +51,36 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . 3 3. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 3 3.1. Performance Metric . . . . . . . . . . . . . . . . . . . 3 3.2. Method of Measurement . . . . . . . . . . . . . . . . . . 4 3.3. Observation Point . . . . . . . . . . . . . . . . . . . . 4 3.4. Active Methods . . . . . . . . . . . . . . . . . . . . . 4 - 3.5. Active Metric . . . . . . . . . . . . . . . . . . . . . . 4 + 3.5. Active Metric . . . . . . . . . . . . . . . . . . . . . . 5 3.6. Passive Methods . . . . . . . . . . . . . . . . . . . . . 5 - 3.7. Passive Metric . . . . . . . . . . . . . . . . . . . . . 5 + 3.7. Passive Metric . . . . . . . . . . . . . . . . . . . . . 6 3.8. Hybrid Methods and Metrics . . . . . . . . . . . . . . . 6 4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Graphical Representation . . . . . . . . . . . . . . . . 7 - 4.2. Discussion of PDM . . . . . . . . . . . . . . . . . . . . 9 - 4.3. Discussion of "Coloring" Method . . . . . . . . . . . . . 10 - 5. Security considerations . . . . . . . . . . . . . . . . . . . 10 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 - 8.2. Informative References . . . . . . . . . . . . . . . . . 11 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12 + 4.2. Discussion of PDM . . . . . . . . . . . . . . . . . . . . 10 + 4.3. Discussion of "Coloring" Method . . . . . . . . . . . . . 11 + 4.4. Brief Discussion of OAM Methods . . . . . . . . . . . . . 11 + 5. Security considerations . . . . . . . . . . . . . . . . . . . 12 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 + 8.2. Informative References . . . . . . . . . . . . . . . . . 13 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction The adjectives "active" and "passive" have been used for many years to distinguish two different classes of Internet performance assessment. The first Passive and Active Measurement (PAM) Conference was held in 2000, but the earliest proceedings available on-line are from the second PAM conference in 2001 [https://www.ripe.net/ripe/meetings/pam-2001]. @@ -133,57 +134,62 @@ "population of interest" defined in clause 6.1.1 of ITU-T Recommendation Y.1540 [Y.1540]. The definitions are consistent with [I-D.zheng-ippm-framework-passive]. 3.1. Performance Metric The standard definition of a quantity, produced in an assessment of performance and/or reliability of the network, which has an intended utility and is carefully specified to convey the exact meaning of a measured value. (This definition is consistent with that of - Performance Metric in RFC 2330 and RFC 6390). + Performance Metric in [RFC2330] and [RFC6390]). 3.2. Method of Measurement The procedure or set of operations having the object of determining a Measured Value or Measurement Result. 3.3. Observation Point See section 2 of [RFC7011] for this definition (a location in the network where packets can be observed), and related definitions. The comparable term defined in IETF literature on Active measurement is Measurement Point, see section 4.1 of [RFC5835]. Two terms have come into use describing similar actions at the identified point in the network path. 3.4. Active Methods Active measurement methods have the following attributes: 1. Commonly, the packet stream of interest is generated as the basis - of measurement. Another packet stream may be generated to - increase traffic load, but the loading stream itself may not be - measured. + of measurement. Sometimes, the adjective "synthetic" is used to + categorize Active measurement streams [Y.1731]. Accompanying + packet stream(s) may be generated to increase overall traffic + load, though the loading stream(s) may not be measured. - 2. The packets in the stream of interest have fields (or are - augmented or modified to include fields) which are dedicated to - measurement. Since measurement usually requires determining the - corresponding packets at multiple measurement points, a sequence - number is the most common information dedicated to measurement. + 2. The packets in the stream of interest have fields or field values + (or are augmented or modified to include fields or field values) + which are dedicated to measurement. Since measurement usually + requires determining the corresponding packets at multiple + measurement points, a sequence number is the most common + information dedicated to measurement, often combined with a + timestamp. 3. The Source and Destination of the packet stream of interest are - usually known a' priori. + usually known a priori. 4. The characteristics of the packet stream of interest are known at the Source at least, and may be communicated to Destination as - part of the method. + part of the method. Note that some packet characteristics will + normaly change during packet forwarding. Other changes along the + path are possible, see [I-D.morton-ippm-2330-stdform-typep]. When adding traffic to the network for measurement, Active Methods influence the quantities measured to some degree, and those performing tests should take steps to quantify the effect(s) and/or minimize such effects. 3.5. Active Metric An Active Metric incorporates one or more of the aspects of Active Methods in the metric definition. @@ -193,21 +199,23 @@ characteristics as metric input parameters, and also specify the packet characteristics (Type-P) and Source and Destination IP addresses (with their implications on both stream treatment and interfaces associated with measurement points). 3.6. Passive Methods Passive measurement methods are o based solely on observations of undisturbed and unmodified packet - stream of interest + stream of interest (in other words, the method of measurement MUST + NOT add, change, or remove fields, or change field values anywhere + along the path). o dependent on the existence of one or more packet streams to supply the stream of interest o dependent on the presence of the packet stream of interest at one or more designated observation points. Some passive methods simply observe and collect information on all packets that pass Observation Point(s), while others filter the packets as a first step and only collect information on packets that @@ -232,58 +240,67 @@ Passive Metrics apply to observations of packet traffic (traffic flows in [RFC7011]). Passive performance metrics are assessed independent of the packets or traffic flows, and solely through observation. Some refer to such assessments as "out-of-band". One example of passive performance metrics for IP packet transfer can be found in ITU-T Recommendation Y.1540 [Y.1540], where the metrics - are defined on the basis of reference events as packet pass reference - points, so the metrics are agnostic to the distinction between active - and passive when the necessary packet correspondence can be derived - from the observed stream of interest as required. + are defined on the basis of reference events generated as packet pass + reference points. The metrics are agnostic to the distinction + between active and passive when the necessary packet correspondence + can be derived from the observed stream of interest as required. 3.8. Hybrid Methods and Metrics Hybrid Methods are Methods of Measurement which use a combination of Active Methods and Passive Methods, to assess Active Metrics, Passive Metrics, or new metrics derived from the a' priori knowledge and observations of the stream of interest. ITU-T Recommendation Y.1540 - [Y.1540] defines metrics are applicable to the hybrid category, since - packet correspondence at different observation/reference points could - be derived from "fields which are dedicated to measurement", but - otherwise the methods are passive. + [Y.1540] defines metrics that are also applicable to the hybrid + categories, since packet correspondence at different observation/ + reference points could be derived from "fields or field values which + are dedicated to measurement", but otherwise the methods are passive. There are several types of Hybrid methods, as categorized below. With respect to a *single* stream of interest, Hybrid Type I methods fit in the continuum as follows, in terms of what happens at the Source (or Observation Point nearby): o If you generate the stream of interest => Active - o If you augment of modify a stream of interest => Hybrid Type I + o If you augment or modify the stream of interest, or employ methods + that modify the treatment of the stream => Hybrid Type I o If you solely observe a stream of interest => Passive + As an example, consider the case where the method generates traffic + load stream(s), and observes an existing stream of interest according + to the criteria for Passive Methods. Since loading streams are an + aspect of Active Methods, the stream of interest is not "solely + observed", and the measurements involve a single stream of interest + whose treatment has been modified both the presence of the load. + Therefore, this is a Hybrid Type I method. + We define Hybrid Type II as follows: Methods that employ two or more different streams of interest with some degree of mutual coordination - (one or more Active streams and one or more undisturbed and + (e.g., one or more Active streams and one or more undisturbed and unmodified packet streams) to collect both Active and Passive Metrics and enable enhanced characterization from additional joint analysis. [I-D.trammell-ippm-hybrid-ps] presents a problem statement for Hybrid Type II methods and metrics. Note that one or more Hybrid Type I streams could be substituted for the Active streams or undisturbed streams in the mutually coordinated set. It is the Type II Methods - where unique Hybrid Metrics are atnticipated to emerge. + where unique Hybrid Metrics are anticipated to emerge. Methods based on a combination of a single (generated) Active stream and Passive observations applied to the stream of interest at intermediate observation points are also a type of Hybrid Methods. However, [RFC5644] already defines these as Spatial Metrics and Methods. It is possible to replace the Active stream of [RFC5644] with a Hybrid Type I stream and measure Spatial Metrics (but this was un-anticipated when [RFC5644] was developed). The Table below illustrates the categorization of methods (where @@ -309,63 +326,66 @@ 4.1. Graphical Representation If we compare the Active and Passive Methods, there are at least two dimensions on which methods can be evaluated. This evaluation space may be useful when a method is a combination of the two alternative methods. The two dimensions (initially chosen) are: - 1. The degree to which the stream of interest effects overall - network conditions experienced by that stream and other streams. - This is a key dimension for Active measurement error analysis. - (Comment: There is also the notion of time averages - a - measurement stream may have significant effect while it is - present, but the stream is only generated 0.1% of the time. On - the other hand, observations alone have no effect on network - performance. To keep things simple, we consider the stream - effect only when it is present.) + Y-Axis: "Effect of the measured stream on network conditions." The + degree to which the stream of interest biases overall network + conditions experienced by that stream and other streams. This is + a key dimension for Active measurement error analysis. (Comment: + There is also the notion of time averages - a measurement stream + may have significant effect while it is present, but the stream is + only generated 0.1% of the time. On the other hand, observations + alone have no effect on network performance. To keep these + dimensions simple, we consider the stream effect only when it is + present, but note that reactive networks defined in [RFC7312] may + exhibit bias for some time beyond the life of a stream.) - 2. The degree to which stream characteristics are know a' priori. - There are methodological advantages of knowing the source stream - characteristics, and having complete control of the stream - characteristics. For example, knowing the number of packets in a - stream allows more efficient operation of the measurement - receiver, and so is an asset for active measurement methods. - Passive methods (with no sample filter) have few clues available - to anticipate what the protocol first packet observed will use or - how many packets will comprise the flow, but once the standard - protocol of a flow is known the possibilities narrow (for some - compliant flows). Therefore this is a key dimension for Passive - measurement error analysis. + X-Axis: "a priori Stream Knowledge." The degree to which stream + characteristics are know a' priori. There are methodological + advantages of knowing the source stream characteristics, and + having complete control of the stream characteristics. For + example, knowing the number of packets in a stream allows more + efficient operation of the measurement receiver, and so is an + asset for active measurement methods. Passive methods (with no + sample filter) have few clues available to anticipate what the + protocol first packet observed will use or how many packets will + comprise the flow, but once the standard protocol of a flow is + known the possibilities narrow (for some compliant flows). + Therefore this is a key dimension for Passive measurement error + analysis. There are a few examples we can plot on a two-dimensional space. We can anchor the dimensions with reference point descriptions. - Effect of the measured stream on network conditions + Y-Axis:Effect of the measured stream on network conditions ^ Max |* Active using max capacity stream | | | | |* Active using stream with load of typical user | | | |* Active using extremely sparse, randomized stream | * PDM Passive | Min * +----------------------------------------------------------------| | | - Stream No Stream + Stream X-Axis: a priori Stream Knowledge No Stream Characteristics Characteristics completely Known known We recognize that method categorization could be based on additional dimensions, but this would require a different graphical approach. For example, "effect of stream of interest on network conditions" could easily be further qualified into: @@ -379,24 +399,23 @@ minimal size packets typically has little effect on other flows (and itself), while a stream designed to characterize path capacity may effect all other flows passing through the capacity bottleneck (including itself). 3. effect on network conditions resulting in network adaptation: for example, a network monitoring load and congestion conditions might change routing, placing some flows to alternate paths to mitigate the congestion. - At present, we have combined 1 and 2 on one axis, as examination of - examples indicates strong correlation of affects on this pair, and - network adaptation is not addressed. As suggestions emerge we will - re-examine the possibilities. + We have combined 1 and 2 on the Y-axis, as examination of examples + indicates strong correlation of affects in this pair, and network + adaptation is not addressed. It is apparent that different methods of IP network measurement can produce different results, even when measuring the same path at the same time. The two dimensions of the graph help to understand how the results might change with the method chosen. For example, an Active Method to assess throughput adds some amount of traffic to the network which might result in lower throughput for all streams. However, a Passive Method to assess throughput can also err on the low side due to unknown limitations of the hosts providing traffic, competition for host resources, limitations of the network interface, @@ -413,78 +432,108 @@ 4.2. Discussion of PDM In [I-D.ietf-ippm-6man-pdm-option], an IPv6 Option Header for Performance and Diagnostic Measurements (PDM) is described which (when added to the stream of interest at strategic interfaces) supports performance measurements. This method processes a user traffic stream and adds "fields which are dedicated to measurement". Thus: - o The method may have a small effect on the measured stream and - other streams in the network. + o The method intends to have a small effect on the measured stream + and other streams in the network. There are conditions where this + intent may not be realized. o The measured stream has unknown characteristics until it is processed to add the PDM Option header. We conclude that this is a Hybrid Type I method, having at least one - characteristic of both active and passive methods. + characteristic of both active and passive methods for a single stream + of interest. 4.3. Discussion of "Coloring" Method Draft [I-D.tempia-opsawg-p3m], proposed to color packets by re- writing a field of the stream at strategic interfaces to support performance measurements. This method processes a user traffic - stream and inserts "fields which are dedicated to measurement". - Thus: + stream and inserts "fields or values which are dedicated to + measurement". Thus: - o The method may have a small effect on the measured stream and - other streams in the network (smaller than PDM above). + o The method intends to have a small effect on the measured stream + and other streams in the network (smaller than PDM above). There + are conditions where this intent may not be realized. o The measured stream has unknown characteristics until it is processed to add the coloring in the header, and the stream could be measured and time-stamped during that process. We note that [I-D.chen-ippm-coloring-based-ipfpm-framework] proposes a method similar to [I-D.tempia-opsawg-p3m], and ippm-list discussion indicates [I-D.chen-ippm-coloring-based-ipfpm-framework] may be covered by the same IPR as [I-D.tempia-opsawg-p3m]. We conclude that this is a Hybrid Type I method, having at least one - characteristic of both active and passive methods. + characteristic of both active and passive methods for a single stream + of interest. + +4.4. Brief Discussion of OAM Methods + + Many Operations, Administration, and Management (OAM) methods exist + beyond the IP-layer. For example, [Y.1731] defines several different + measurement methods which we would classify as follows: + + o Loss Measurement (LM) occasionally injects frames with a count of + previous frames since the last LM message. We conclude LM is + Hybrid Type I because + + A. This method processes a user traffic stream, + + B. and augments the stream of interest with frames having "fields + which are dedicated to measurement". + + o Synthetic Loss Measurement (SLM) and Delay Measurement (DM) + methods both inject dedicated measurement frames, so the "stream + of interest is generated as the basis of measurement". We + conclude that SLM and DM methods are Active Methods. + + We also recognize the existance of alternate terminology used in OAM + at layers other than IP. Readers are encouraged to consult [RFC6374] + for MPLS Loss and Delay measurement terminology, for example. 5. Security considerations When considering privacy of those involved in measurement or those whose traffic is measured, there is sensitive information communicated and observed at observation and measurement points described above. We refer the reader to the privacy considerations described in the Large Scale Measurement of Broadband Performance - (LMAP) Framework [I-D.ietf-lmap-framework], which covers active and - passive measurement techniques and supporting material on measurement + (LMAP) Framework [RFC7594], which covers active and passive + measurement techniques and supporting material on measurement context. 6. IANA Considerations This memo makes no requests for IANA consideration. 7. Acknowledgements Thanks to Mike Ackermann for asking the right question, and for several suggestions on terminology. Brian Trammell provided key terms and references for the passive category, and suggested ways to expand the Hybrid description and types. Phil Eardley suggested some hybrid scenaios for categorization as part of his review. Tiziano Ionta reviewed the draft and suggested the classification for the "coloring" method of measurement. Nalini Elkins identified several areas for clarification following her review. Bill Jouris suggested - several editorial improvements. + several editorial improvements. Tal Mizrahi and Joachim Fabini + raised many key considerations in their reviews, based on their broad + measurement experience. 8. References 8.1. Normative References [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, DOI 10.17487/RFC2330, May 1998, . @@ -500,38 +549,60 @@ [RFC5644] Stephan, E., Liang, L., and A. Morton, "IP Performance Metrics (IPPM): Spatial and Multicast", RFC 5644, DOI 10.17487/RFC5644, October 2009, . [RFC5835] Morton, A., Ed. and S. Van den Berghe, Ed., "Framework for Metric Composition", RFC 5835, DOI 10.17487/RFC5835, April 2010, . + [RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New + Performance Metric Development", BCP 170, RFC 6390, + DOI 10.17487/RFC6390, October 2011, + . + [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013, . + [RFC7312] Fabini, J. and A. Morton, "Advanced Stream and Sampling + Framework for IP Performance Metrics (IPPM)", RFC 7312, + DOI 10.17487/RFC7312, August 2014, + . + + [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, + . + 8.2. Informative References - [I-D.ietf-lmap-framework] - Eardley, P., Morton, A., Bagnulo, M., Burbridge, T., - Aitken, P., and A. Akhter, "A framework for Large-Scale - Measurement of Broadband Performance (LMAP)", draft-ietf- - lmap-framework-14 (work in progress), April 2015. + [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay + Measurement for MPLS Networks", RFC 6374, + DOI 10.17487/RFC6374, September 2011, + . + + [I-D.morton-ippm-2330-stdform-typep] + Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V. + Hegde, "Updates for IPPM's Active Metric Framework: + Packets of Type-P and Standard-Formed Packets", draft- + morton-ippm-2330-stdform-typep-01 (work in progress), + October 2015. [I-D.ietf-ippm-6man-pdm-option] Elkins, N. and M. Ackermann, "IPv6 Performance and Diagnostic Metrics (PDM) Destination Option", draft-ietf- - ippm-6man-pdm-option-00 (work in progress), June 2015. + ippm-6man-pdm-option-01 (work in progress), October 2015. [I-D.tempia-opsawg-p3m] Capello, A., Cociglio, M., Castaldelli, L., and A. Bonda, "A packet based method for passive performance monitoring", draft-tempia-opsawg-p3m-04 (work in progress), February 2014. [I-D.chen-ippm-coloring-based-ipfpm-framework] Chen, M., Zheng, L., Mirsky, G., and G. Fioccola, "IP Flow Performance Measurement Framework", draft-chen-ippm- @@ -546,19 +617,23 @@ [I-D.trammell-ippm-hybrid-ps] Trammell, B., Zheng, L., Berenguer, S., and M. Bagnulo, "Hybrid Measurement using IPPM Metrics", draft-trammell- ippm-hybrid-ps-01 (work in progress), February 2014. [Y.1540] ITU-T Recommendation Y.1540, , "Internet protocol data communication service - IP packet transfer and availability performance parameters", March 2011. + [Y.1731] ITU-T Recommendation Y.1731, , "Operation, administration + and management (OAM) functions and mechanisms for + Ethernet-based networks", October 2015. + Author's Address Al Morton AT&T Labs 200 Laurel Avenue South Middletown, NJ USA Email: acmorton@att.com