Network Working Group L. Ciavattone Internet-Draft AT&T Labs Intended status: Informational R. Geib Expires: January 9, 2013 Deutsche Telekom A. Morton AT&T Labs M. Wieser Technical University Darmstadt July 8, 2012 Test Plan and Results for Advancing RFC 2680 on the Standards Track draft-ietf-ippm-testplan-rfc2680-00 Abstract This memo proposes to advance a performance metric RFC along the standards track, specifically RFC 2680 on One-way Loss Metrics. Observing that the metric definitions themselves should be the primary focus rather than the implementations of metrics, this memo describes the test procedures to evaluate specific metric requirement clauses to determine if the requirement has been interpreted and implemented as intended. Two completely independent implementations have been tested against the key specifications of RFC 2680. In this version, the results are presented in the R-tool output form. Beautification is future work. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." Ciavattone, et al. Expires January 9, 2013 [Page 1] Internet-Draft Stds Track Tests RFC2680 July 2012 This Internet-Draft will expire on January 9, 2013. Copyright Notice Copyright (c) 2012 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 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Ciavattone, et al. Expires January 9, 2013 [Page 2] Internet-Draft Stds Track Tests RFC2680 July 2012 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. RFC 2680 Coverage . . . . . . . . . . . . . . . . . . . . 4 2. A Definition-centric metric advancement process . . . . . . . 5 3. Test configuration . . . . . . . . . . . . . . . . . . . . . . 5 4. Error Calibration, RFC 2680 . . . . . . . . . . . . . . . . . 9 4.1. Clock Synchronization Calibration . . . . . . . . . . . . 9 4.2. Packet Loss Determination Error . . . . . . . . . . . . . 9 5. Pre-determined Limits on Equivalence . . . . . . . . . . . . . 10 6. Tests to evaluate RFC 2680 Specifications . . . . . . . . . . 11 6.1. One-way Loss, ADK Sample Comparison . . . . . . . . . . . 11 6.1.1. 340B/Periodic Cross-imp. results . . . . . . . . . . . 12 6.1.2. 64B/Periodic Cross-imp. results . . . . . . . . . . . 13 6.1.3. 64B/Poisson Cross-imp. results . . . . . . . . . . . . 14 6.1.4. Conclusions on the ADK Results for One-way Packet Loss . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.2. One-way Loss, Delay threshold . . . . . . . . . . . . . . 15 6.2.1. NetProbe results for Loss Threshold . . . . . . . . . 16 6.2.2. Perfas Results for Loss Threshold . . . . . . . . . . 17 6.2.3. Conclusions for Loss Threshold . . . . . . . . . . . . 17 6.3. One-way Loss with Out-of-Order Arrival . . . . . . . . . . 17 6.4. Poisson Sending Process Evaluation . . . . . . . . . . . . 18 6.4.1. NetProbe Results . . . . . . . . . . . . . . . . . . . 19 6.4.2. Perfas Results . . . . . . . . . . . . . . . . . . . . 20 6.4.3. Conclusions for Goodness-of-Fit . . . . . . . . . . . 22 6.5. Implementation of Statistics for One-way Delay . . . . . . 22 7. Security Considerations . . . . . . . . . . . . . . . . . . . 22 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 10.1. Normative References . . . . . . . . . . . . . . . . . . . 23 10.2. Informative References . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25 Ciavattone, et al. Expires January 9, 2013 [Page 3] Internet-Draft Stds Track Tests RFC2680 July 2012 1. Introduction The IETF (IP Performance Metrics working group, IPPM) has considered how to advance their metrics along the standards track since 2001. A renewed work effort sought to investigate ways in which the measurement variability could be reduced and thereby simplify the problem of comparison for equivalence. There is consensus [I-D.ietf-ippm-metrictest] that the metric definitions should be the primary focus of evaluation rather than the implementations of metrics, and equivalent results are deemed to be evidence that the metric specifications are clear and unambiguous. This is the metric specification equivalent of protocol interoperability. The advancement process either produces confidence that the metric definitions and supporting material are clearly worded and unambiguous, OR, identifies ways in which the metric definitions should be revised to achieve clarity. The process should also permit identification of options that were not implemented, so that they can be removed from the advancing specification (this is an aspect more typical of protocol advancement along the standards track). This memo's purpose is to implement the current approach for [RFC2680]. In particular, this memo documents consensus on the extent of tolerable errors when assessing equivalence in the results. In discussions, the IPPM working group agreed that test plan and procedures should include the threshold for determining equivalence, and this information should be available in advance of cross- implementation comparisons. This memo includes procedures for same- implementation comparisons to help set the equivalence threshold. Another aspect of the metric RFC advancement process is the requirement to document the work and results. The procedures of [RFC2026] are expanded in[RFC5657], including sample implementation and interoperability reports. This memo follows the template in [I-D.morton-ippm-advance-metrics] for the report that accompanies the protocol action request submitted to the Area Director, including description of the test set-up, procedures, results for each implementation and conclusions. 1.1. RFC 2680 Coverage This plan is intended to cover all critical requirements and sections of [RFC2680]. Ciavattone, et al. Expires January 9, 2013 [Page 4] Internet-Draft Stds Track Tests RFC2680 July 2012 Note that there are only five instances of the requirement term "MUST" in [RFC2680] outside of the boilerplate and [RFC2119] reference. Material may be added as it is "discovered" (apparently, not all requirements use requirements language). 2. A Definition-centric metric advancement process The process described in Section 3.5 of [I-D.ietf-ippm-metrictest] takes as a first principle that the metric definitions, embodied in the text of the RFCs, are the objects that require evaluation and possible revision in order to advance to the next step on the standards track. IF two implementations do not measure an equivalent singleton or sample, or produce the an equivalent statistic, AND sources of measurement error do not adequately explain the lack of agreement, THEN the details of each implementation should be audited along with the exact definition text, to determine if there is a lack of clarity that has caused the implementations to vary in a way that affects the correspondence of the results. IF there was a lack of clarity or multiple legitimate interpretations of the definition text, THEN the text should be modified and the resulting memo proposed for consensus and advancement along the standards track. Finally, all the findings MUST be documented in a report that can support advancement on the standards track, similar to those described in [RFC5657]. The list of measurement devices used in testing satisfies the implementation requirement, while the test results provide information on the quality of each specification in the metric RFC (the surrogate for feature interoperability). 3. Test configuration One metric implementation used was NetProbe version 5.8.5, (an earlier version is used in the WIPM system and deployed world-wide). NetProbe uses UDP packets of variable size, and can produce test streams with Periodic [RFC3432] or Poisson [RFC2330] sample distributions. Ciavattone, et al. Expires January 9, 2013 [Page 5] Internet-Draft Stds Track Tests RFC2680 July 2012 The other metric implementation used was Perfas+ version 3.1, developed by Deutsche Telekom. Perfas+ uses UDP unicast packets of variable size (but supports also TCP and multicast). Test streams with periodic, Poisson or uniform sample distributions may be used. Figure 1 shows a view of the test path as each Implementation's test flows pass through the Internet and the L2TPv3 tunnel IDs (1 and 2), based on Figure 1 of [I-D.ietf-ippm-metrictest]. +----+ +----+ +----+ +----+ |Imp1| |Imp1| ,---. |Imp2| |Imp2| +----+ +----+ / \ +-------+ +----+ +----+ | V100 | V200 / \ | Tunnel| | V300 | V400 | | ( ) | Head | | | +--------+ +------+ | |__| Router| +----------+ |Ethernet| |Tunnel| |Internet | +---B---+ |Ethernet | |Switch |--|Head |-| | | |Switch | +-+--+---+ |Router| | | +---+---+--+--+--+----+ |__| +--A---+ ( ) |Network| |__| \ / |Emulat.| U-turn \ / |"netem"| U-turn V300 to V400 `-+-' +-------+ V100 to V200 Implementations ,---. +--------+ +~~~~~~~~~~~/ \~~~~~~| Remote | +------->-----F2->-| / \ |->---. | | +---------+ | Tunnel ( ) | | | | | transmit|-F1->-| ID 1 ( ) |->. | | | | Imp 1 | +~~~~~~~~~| |~~~~| | | | | | receive |-<--+ ( ) | F1 F2 | | +---------+ | |Internet | | | | | *-------<-----+ F1 | | | | | | +---------+ | | +~~~~~~~~~| |~~~~| | | | | transmit|-* *-| | | |<-* | | | Imp 2 | | Tunnel ( ) | | | | receive |-<-F2-| ID 2 \ / |<----* | +---------+ +~~~~~~~~~~~\ /~~~~~~| Switch | `-+-' +--------+ Illustrations of a test setup with a bi-directional tunnel. The upper diagram emphasizes the VLAN connectivity and geographical location. The lower diagram shows example flows traveling between two measurement implementations (for simplicity, only two flows are shown). Figure 1 Ciavattone, et al. Expires January 9, 2013 [Page 6] Internet-Draft Stds Track Tests RFC2680 July 2012 The testing employs the Layer 2 Tunnel Protocol, version 3 (L2TPv3) [RFC3931] tunnel between test sites on the Internet. The tunnel IP and L2TPv3 headers are intended to conceal the test equipment addresses and ports from hash functions that would tend to spread different test streams across parallel network resources, with likely variation in performance as a result. At each end of the tunnel, one pair of VLANs encapsulated in the tunnel are looped-back so that test traffic is returned to each test site. Thus, test streams traverse the L2TP tunnel twice, but appear to be one-way tests from the test equipment point of view. The network emulator is a host running Fedora 14 Linux [http://fedoraproject.org/] with IP forwarding enabled and the "netem" Network emulator as part of the Fedora Kernel 2.6.35.11 [http ://www.linuxfoundation.org/collaborate/workgroups/networking/netem] loaded and operating. Connectivity across the netem/Fedora host was accomplished by bridging Ethernet VLAN interfaces together with "brctl" commands (e.g., eth1.100 <-> eth2.100). The netem emulator was activated on one interface (eth1) and only operates on test streams traveling in one direction. In some tests, independent netem instances operated separately on each VLAN. The links between the netem emulator host and router and switch were found to be 100baseTx-HD (100Mbps half duplex) as reported by "mii- tool"when the testing was complete. Use of Half Duplex was not intended, but probably added a small amount of delay variation that could have been avoided in full duplex mode. Each individual test was run with common packet rates (1 pps, 10pps) Poisson/Periodic distributions, and IP packet sizes of 64, 340, and 500 Bytes. For these tests, a stream of at least 300 packets were sent from Source to Destination in each implementation. Periodic streams (as per [RFC3432]) with 1 second spacing were used, except as noted. As required in Section 2.8.1 of [RFC2680], packet Type-P must be reported. The packet Type-P for this test was IP-UDP with Best Effort DCSP. These headers were encapsulated according to the L2TPv3 specifications [RFC3931], and thus may not influence the treatment received as the packets traversed the Internet. With the L2TPv3 tunnel in use, the metric name for the testing configured here (with respect to the IP header exposed to Internet processing) is: Type-IP-protocol-115-One-way-Packet-Loss--Stream Ciavattone, et al. Expires January 9, 2013 [Page 7] Internet-Draft Stds Track Tests RFC2680 July 2012 With (Section 3.2. [RFC2680]) Metric Parameters: + Src, the IP address of a host (12.3.167.16 or 193.159.144.8) + Dst, the IP address of a host (193.159.144.8 or 12.3.167.16) + T0, a time + Tf, a time + lambda, a rate in reciprocal seconds + Thresh, a maximum waiting time in seconds (see Section 2.8.2 of [RFC2680]) and (Section 3.8. [RFC2680]) Metric Units: A sequence of pairs; the elements of each pair are: + T, a time, and + L, either a zero or a one The values of T in the sequence are monotonic increasing. Note that T would be a valid parameter to the *singleton* Type-P-One-way- Packet-Loss, and that L would be a valid value of Type-P-One-way- Packet Loss (see Section 2 of [RFC2680]). Also, Section 2.8.4 of [RFC2680] recommends that the path SHOULD be reported. In this test set-up, most of the path details will be concealed from the implementations by the L2TPv3 tunnels, thus a more informative path trace route can be conducted by the routers at each location. When NetProbe is used in production, a traceroute is conducted in parallel at the outset of measurements. Perfas+ does not support traceroute. Ciavattone, et al. Expires January 9, 2013 [Page 8] Internet-Draft Stds Track Tests RFC2680 July 2012 IPLGW#traceroute 193.159.144.8 Type escape sequence to abort. Tracing the route to 193.159.144.8 1 12.126.218.245 [AS 7018] 0 msec 0 msec 4 msec 2 cr84.n54ny.ip.att.net (12.123.2.158) [AS 7018] 4 msec 4 msec cr83.n54ny.ip.att.net (12.123.2.26) [AS 7018] 4 msec 3 cr1.n54ny.ip.att.net (12.122.105.49) [AS 7018] 4 msec cr2.n54ny.ip.att.net (12.122.115.93) [AS 7018] 0 msec cr1.n54ny.ip.att.net (12.122.105.49) [AS 7018] 0 msec 4 n54ny02jt.ip.att.net (12.122.80.225) [AS 7018] 4 msec 0 msec n54ny02jt.ip.att.net (12.122.80.237) [AS 7018] 4 msec 5 192.205.34.182 [AS 7018] 0 msec 192.205.34.150 [AS 7018] 0 msec 192.205.34.182 [AS 7018] 4 msec 6 da-rg12-i.DA.DE.NET.DTAG.DE (62.154.1.30) [AS 3320] 88 msec 88 msec 88 msec 7 217.89.29.62 [AS 3320] 88 msec 88 msec 88 msec 8 217.89.29.55 [AS 3320] 88 msec 88 msec 88 msec 9 * * * It was only possible to conduct the traceroute for the measured path on one of the tunnel-head routers (the normal trace facilities of the measurement systems are confounded by the L2TPv3 tunnel encapsulation). 4. Error Calibration, RFC 2680 An implementation is required to report calibration results on clock synchronization in Section 2.8.3 of [RFC2680] (also required in Section 3.7 of [RFC2680] for sample metrics). Also, it is recommended to report the probability that a packet successfully arriving at the destination network interface is incorrectly designated as lost due to resource exhaustion in Section 2.8.3 of [RFC2680]. 4.1. Clock Synchronization Calibration For NetProbe and Perfas clock synchronization test results, refer to Section 4 of [I-D.ietf-ippm-testplan-rfc2679]. 4.2. Packet Loss Determination Error Since both measurement implementations have resource limitations, it is theoretically possible that these limits could be exceeded and a Ciavattone, et al. Expires January 9, 2013 [Page 9] Internet-Draft Stds Track Tests RFC2680 July 2012 packet that arrived at the destination successfully might be discarded in error. In previous test efforts [I-D.morton-ippm-advance-metrics], NetProbe produced 6 multicast streams with an aggregate bit rate over 53 Mbit/s, in order to characterize the 1-way capacity of a NISTNet- based emulator. Neither the emulator nor the pair of NetProbe implementations used in this testing dropped any packets in these streams. The maximum load used here between any 2 NetProbe implementations was be 11.5 Mbit/s divided equally among 3 unicast test streams. We conclude that steady resource usage does not contribute error (additional loss) to the measurements. 5. Pre-determined Limits on Equivalence In this section, we provide the numerical limits on comparisons between implementations, in order to declare that the results are equivalent and therefore, the tested specification is clear. A key point is that the allowable errors, corrections, and confidence levels only need to be sufficient to detect mis-interpretation of the tested specification resulting in diverging implementations. Also, the allowable error must be sufficient to compensate for measured path differences. It was simply not possible to measure fully identical paths in the VLAN-loopback test configuration used, and this practical compromise must be taken into account. For Anderson-Darling K-sample (ADK) [ADK] comparisons, the required confidence factor for the cross-implementation comparisons SHALL be the smallest of: o 0.95 confidence factor at 1 packet resolution, or o the smallest confidence factor (in combination with resolution) of the two same-implementation comparisons for the same test conditions (if the number of streams is sufficient to allow such comparisons). For Anderson-Darling Goodness-of-Fit (ADGoF) [Radgof] comparisons, the required level of significance for the same-implementation Goodness-of-Fit (GoF) SHALL be 0.05 or 5%, as specified in Section 11.4 of [RFC2330]. This is equivalent to a 95% confidence factor. Ciavattone, et al. Expires January 9, 2013 [Page 10] Internet-Draft Stds Track Tests RFC2680 July 2012 6. Tests to evaluate RFC 2680 Specifications This section describes some results from production network (cross- Internet) tests with measurement devices implementing IPPM metrics and a network emulator to create relevant conditions, to determine whether the metric definitions were interpreted consistently by implementors. The procedures are similar contained in Appendix A.1 of [I-D.ietf-ippm-metrictest] for One-way Delay. 6.1. One-way Loss, ADK Sample Comparison This test determines if implementations produce results that appear to come from a common packet loss distribution, as an overall evaluation of Section 3 of [RFC2680], "A Definition for Samples of One-way Packet Loss". Same-implementation comparison results help to set the threshold of equivalence that will be applied to cross- implementation comparisons. This test is intended to evaluate measurements in sections 2, 3, and 4 of [RFC2680]. By testing the extent to which the counts of one-way packet loss counts on different test streams of two [RFC2680] implementations appear to be from the same loss process, we reduce comparison steps because comparing the resulting summary statistics (as defined in Section 4 of [RFC2680]) would require a redundant set of equivalence evaluations. We can easily check whether the single statistic in Section 4 of [RFC2680] was implemented, and report on that fact. 1. Configure an L2TPv3 path between test sites, and each pair of measurement devices to operate tests in their designated pair of VLANs. 2. Measure a sample of one-way packet loss singletons with 2 or more implementations, using identical options and network emulator settings (if used). 3. Measure a sample of one-way packet loss singletons with *four or more* instances of the *same* implementations, using identical options, noting that connectivity differences SHOULD be the same as for the cross implementation testing. 4. If less than ten test streams are available, skip to step 7. 5. Apply the ADK comparison procedures (see Appendix C of [I-D.ietf-ippm-metrictest]) and determine the resolution and Ciavattone, et al. Expires January 9, 2013 [Page 11] Internet-Draft Stds Track Tests RFC2680 July 2012 confidence factor for distribution equivalence of each same- implementation comparison and each cross-implementation comparison. 6. Take the coarsest resolution and confidence factor for distribution equivalence from the same-implementation pairs, or the limit defined in Section 5 above, as a limit on the equivalence threshold for these experimental conditions. 7. Compare the cross-implementation ADK performance with the equivalence threshold determined in step 5 to determine if equivalence can be declared. The common parameters used for tests in this section are: The cross-implementation comparison uses a simple ADK analysis [Rtool] [Radk], where all NetProbe loss counts are compared with all Perfas loss results. In the result analysis of this section: o All comparisons used 1 packet resolution. o No Correction Factors were applied. o The 0.95 confidence factor (1.960 for cross-implementation comparison) was used. 6.1.1. 340B/Periodic Cross-imp. results Tests described in this section used: o IP header + payload = 340 octets o Periodic sampling at 1 packet per second o Test duration = 1200 seconds (during April 7, 2011, EDT) The netem emulator was set for 100ms constant delay, with 10% loss ratio. In this experiment, the netem emulator was configured to operate independently on each VLAN and thus the emulator itself is a potential source of error when comparing streams that traverse the test path in different directions. Ciavattone, et al. Expires January 9, 2013 [Page 12] Internet-Draft Stds Track Tests RFC2680 July 2012 A07bps_loss <- c(114, 175, 138, 142, 181, 105) (NetProbe) A07per_loss <- c(115, 128, 136, 127, 139, 138) (Perfas) > A07bps_loss <- c(114, 175, 138, 142, 181, 105) > A07per_loss <- c(115, 128, 136, 127, 139, 138) > > A07cross_loss_ADK <- adk.test(A07bps_loss, A07per_loss) > A07cross_loss_ADK Anderson-Darling k-sample test. Number of samples: 2 Sample sizes: 6 6 Total number of values: 12 Number of unique values: 11 Mean of Anderson Darling Criterion: 1 Standard deviation of Anderson Darling Criterion: 0.6569 T = (Anderson Darling Criterion - mean)/sigma Null Hypothesis: All samples come from a common population. t.obs P-value extrapolation not adj. for ties 0.52043 0.20604 0 adj. for ties 0.62679 0.18607 0 The cross-implementation comparisons pass the ADK criterion. 6.1.2. 64B/Periodic Cross-imp. results Tests described in this section used: o IP header + payload = 64 octets o Periodic sampling at 1 packet per second o Test duration = 300 seconds (during March 24, 2011, EDT) The netem emulator was set for 0ms constant delay, with 10% loss ratio. Ciavattone, et al. Expires January 9, 2013 [Page 13] Internet-Draft Stds Track Tests RFC2680 July 2012 > M24per_loss <- c(42,34,35,35) (Perfas) > M24apd_23BC_loss <- c(27,39,29,24) (NetProbe) > M24apd_loss23BC_ADK <- adk.test(M24apd_23BC_loss,M24per_loss) > M24apd_loss23BC_ADK Anderson-Darling k-sample test. Number of samples: 2 Sample sizes: 4 4 Total number of values: 8 Number of unique values: 7 Mean of Anderson Darling Criterion: 1 Standard deviation of Anderson Darling Criterion: 0.60978 T = (Anderson Darling Criterion - mean)/sigma Null Hypothesis: All samples come from a common population. t.obs P-value extrapolation not adj. for ties 0.76921 0.16200 0 adj. for ties 0.90935 0.14113 0 Warning: At least one sample size is less than 5. p-values may not be very accurate. The cross-implementation comparisons pass the ADK criterion. 6.1.3. 64B/Poisson Cross-imp. results Tests described in this section used: o IP header + payload = 64 octets o Poisson sampling at lambda = 1 packet per second o Test duration = 20 minutes (during April 27, 2011, EDT) The netem configuration was 0ms delay and 10% loss, but there were two passes through an emulator for each stream, and loss emulation was present for 18 minutes of the 20 minute test . Ciavattone, et al. Expires January 9, 2013 [Page 14] Internet-Draft Stds Track Tests RFC2680 July 2012 A27aps_loss <- c(91,110,113,102,111,109,112,113) (NetProbe) A27per_loss <- c(95,123,126,114) (Perfas) A27cross_loss_ADK <- adk.test(A27aps_loss, A27per_loss) > A27cross_loss_ADK Anderson-Darling k-sample test. Number of samples: 2 Sample sizes: 8 4 Total number of values: 12 Number of unique values: 11 Mean of Anderson Darling Criterion: 1 Standard deviation of Anderson Darling Criterion: 0.65642 T = (Anderson Darling Criterion - mean)/sigma Null Hypothesis: All samples come from a common population. t.obs P-value extrapolation not adj. for ties 2.15099 0.04145 0 adj. for ties 1.93129 0.05125 0 Warning: At least one sample size is less than 5. p-values may not be very accurate. > The cross-implementation comparisons barely pass the ADK criterion at 95% = 1.960 when adjusting for ties. 6.1.4. Conclusions on the ADK Results for One-way Packet Loss We conclude that the two implementations are capable of producing equivalent one-way packet loss measurements based on their interpretation of [RFC2680] . 6.2. One-way Loss, Delay threshold This test determines if implementations use the same configured maximum waiting time delay from one measurement to another under different delay conditions, and correctly declare packets arriving in excess of the waiting time threshold as lost. See Section 2.8.2 of [RFC2680]. Ciavattone, et al. Expires January 9, 2013 [Page 15] Internet-Draft Stds Track Tests RFC2680 July 2012 1. configure an L2TPv3 path between test sites, and each pair of measurement devices to operate tests in their designated pair of VLANs. 2. configure the network emulator to add 1.0 sec one-way constant delay in one direction of transmission. 3. measure (average) one-way delay with 2 or more implementations, using identical waiting time thresholds (Thresh) for loss set at 3 seconds. 4. configure the network emulator to add 3 sec one-way constant delay in one direction of transmission equivalent to 2 seconds of additional one-way delay (or change the path delay while test is in progress, when there are sufficient packets at the first delay setting) 5. repeat/continue measurements 6. observe that the increase measured in step 5 caused all packets with 2 sec additional delay to be declared lost, and that all packets that arrive successfully in step 3 are assigned a valid one-way delay. The common parameters used for tests in this section are: o IP header + payload = 64 octets o Poisson sampling at lambda = 1 packet per second o Test duration = 900 seconds total (March 21) The netem emulator was set to add constant delays as specified in the procedure above. 6.2.1. NetProbe results for Loss Threshold In NetProbe, the Loss Threshold is implemented uniformly over all packets as a post-processing routine. With the Loss Threshold set at 3 seconds, all packets with one-way delay >3 seconds are marked "Lost" and included in the Lost Packet list with their transmission time (as required in Section 3.3 of [RFC2680]). This resulted in 342 packets designated as lost in one of the test streams (with average delay = 3.091 sec). Ciavattone, et al. Expires January 9, 2013 [Page 16] Internet-Draft Stds Track Tests RFC2680 July 2012 6.2.2. Perfas Results for Loss Threshold Perfas uses a fixed Loss Threshold which was not adjustable during this study. The Loss Threshold is approximately one minute, and emulation of a delay of this size was not attempted. However, it is possible to implement any delay threshold desired with a post- processing routine and subsequent analysis. Using this method, 195 packets would be declared lost (with average delay = 3.091 sec). 6.2.3. Conclusions for Loss Threshold Both implementations assume that any constant delay value desired can be used as the Loss Threshold, since all delays are stored as a pair as required in [RFC2680]. This is a simple way to enforce the constant loss threshold envisioned in [RFC2680] (see specific section reference above). We take the position that the assumption of post-processing is compliant, and that the text of the RFC should be revised slightly to include this point. 6.3. One-way Loss with Out-of-Order Arrival Section 3.6 of [RFC2680] indicates that implementations need to ensure that reordered packets are handled correctly using an uncapitalized "must". In essence, this is an implied requirement because the correct packet must be identified as lost if it fails to arrive before its delay threshold under all circumstances, and reordering is always a possibility on IP network paths. See [RFC4737] for the definition of reordering used in IETF standard- compliant measurements. Using the procedure of section 6.1, the netem emulator was set to introduce significant delay (2000 ms) and delay variation (1000 ms), which was sufficient to produce packet reordering because each packet's emulated delay is independent from others, and 10% loss. The tests described in this section used: o IP header + payload = 64 octets o Periodic sampling = 1 packet per second o Test duration = 600 seconds (during May 2, 2011, EDT) Ciavattone, et al. Expires January 9, 2013 [Page 17] Internet-Draft Stds Track Tests RFC2680 July 2012 > Y02aps_loss <- c(53,45,67,55) (NetProbe) > Y02per_loss <- c(59,62,67,69) (Perfas) > Y02cross_loss_ADK <- adk.test(Y02aps_loss, Y02per_loss) > Y02cross_loss_ADK Anderson-Darling k-sample test. Number of samples: 2 Sample sizes: 4 4 Total number of values: 8 Number of unique values: 7 Mean of Anderson Darling Criterion: 1 Standard deviation of Anderson Darling Criterion: 0.60978 T = (Anderson Darling Criterion - mean)/sigma Null Hypothesis: All samples come from a common population. t.obs P-value extrapolation not adj. for ties 1.11282 0.11531 0 adj. for ties 1.19571 0.10616 0 Warning: At least one sample size is less than 5. p-values may not be very accurate. > The test results indicate that extensive reordering was present. Both implementations capture the extensive delay variation between adjacent packets. In NetProbe, packet arrival order is preserved in the raw measurement files, so an examination of arrival packet sequence numbers also indicates reordering. Despite extensive continuous packet reordering present in the transmission path, the distributions of loss counts from the two implementations pass the ADK criterion at 95% = 1.960. 6.4. Poisson Sending Process Evaluation Section 3.7 of [RFC2680] indicates that implementations need to ensure that their sending process is reasonably close to a classic Poisson distribution when used. Much more detail on sample distribution generation and Goodness-of-Fit testing is specified in Section 11.4 of [RFC2330] and the Appendix of [RFC2330]. In this section, each implementation's Poisson distribution is compared with an idealistic version of the distribution available in the base functionality of the R-tool for Statistical Analysis[Rtool], Ciavattone, et al. Expires January 9, 2013 [Page 18] Internet-Draft Stds Track Tests RFC2680 July 2012 and performed using the Anderson-Darling Goodness-of-Fit test package (ADGofTest) [Radgof]. The Goodness-of-Fit criterion derived from [RFC2330] requires a test statistic value AD <= 2.492 for 5% significance. The Appendix of [RFC2330] also notes that there may be difficulty satisfying the ADGofTest when the sample includes many packets (when 8192 were used, the test always failed, but smaller sets of the stream passed). Both implementations were configured to produce Poisson distributions with lambda = 1 packet per second. 6.4.1. NetProbe Results Section 11.4 of [RFC2330] suggests three possible measurement points to evaluate the Poisson distribution. The NetProbe analysis uses "user-level timestamps made just before or after the system call for transmitting the packet". The statistical summary for two NetProbe streams is below: > summary(a27ms$s1[2:1152]) Min. 1st Qu. Median Mean 3rd Qu. Max. 0.0100 0.2900 0.6600 0.9846 1.3800 8.6390 > summary(a27ms$s2[2:1152]) Min. 1st Qu. Median Mean 3rd Qu. Max. 0.010 0.280 0.670 0.979 1.365 8.829 We see that both the Means are near the specified lambda = 1. The results of ADGoF tests for these two streams is shown below: Ciavattone, et al. Expires January 9, 2013 [Page 19] Internet-Draft Stds Track Tests RFC2680 July 2012 > ad.test( a27ms$s1[2:101], pexp, 1) Anderson-Darling GoF Test data: a27ms$s1[2:101] and pexp AD = 0.8908, p-value = 0.4197 alternative hypothesis: NA > ad.test( a27ms$s1[2:1001], pexp, 1) Anderson-Darling GoF Test data: a27ms$s1[2:1001] and pexp AD = 0.9284, p-value = 0.3971 alternative hypothesis: NA > ad.test( a27ms$s2[2:101], pexp, 1) Anderson-Darling GoF Test data: a27ms$s2[2:101] and pexp AD = 0.3597, p-value = 0.8873 alternative hypothesis: NA > ad.test( a27ms$s2[2:1001], pexp, 1) Anderson-Darling GoF Test data: a27ms$s2[2:1001] and pexp AD = 0.6913, p-value = 0.5661 alternative hypothesis: NA We see that both 100 and 1000 packet sets from two different streams (s1 and s2) all passed the AD <= 2.492 criterion. 6.4.2. Perfas Results Section 11.4 of [RFC2330] suggests three possible measurement points to evaluate the Poisson distribution. The Perfas analysis uses "wire times for the packets as recorded using a packet filter". However, due to limited access at the Perfas side of the test setup, the captures were made after the Perfas streams traversed the production network, adding a small amount of unwanted delay variation to the wire times (and possibly error due to packet loss). The statistical summary for two Perfas streams is below: Ciavattone, et al. Expires January 9, 2013 [Page 20] Internet-Draft Stds Track Tests RFC2680 July 2012 > summary(a27pe$p1) Min. 1st Qu. Median Mean 3rd Qu. Max. 0.004 0.347 0.788 1.054 1.548 4.231 > summary(a27pe$p2) Min. 1st Qu. Median Mean 3rd Qu. Max. 0.0010 0.2710 0.7080 0.9696 1.3740 7.1160 We see that both the Means are near the specified lambda = 1. The results of ADGoF tests for these two streams is shown below: > ad.test(a27pe$p1, pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p1 and pexp AD = 1.1364, p-value = 0.2930 alternative hypothesis: NA > ad.test(a27pe$p2, pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p2 and pexp AD = 0.5041, p-value = 0.7424 alternative hypothesis: NA > ad.test(a27pe$p1[1:100], pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p1[1:100] and pexp AD = 0.7202, p-value = 0.5419 alternative hypothesis: NA > ad.test(a27pe$p1[101:193], pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p1[101:193] and pexp AD = 1.4046, p-value = 0.201 alternative hypothesis: NA > ad.test(a27pe$p2[1:100], pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p2[1:100] and pexp Ciavattone, et al. Expires January 9, 2013 [Page 21] Internet-Draft Stds Track Tests RFC2680 July 2012 AD = 0.4758, p-value = 0.7712 alternative hypothesis: NA > ad.test(a27pe$p2[101:193], pexp, 1 ) Anderson-Darling GoF Test data: a27pe$p2[101:193] and pexp AD = 0.3381, p-value = 0.9068 alternative hypothesis: NA > We see that both 193, 100, and 93 packet sets from two different streams (p1 and p2) all passed the AD <= 2.492 criterion. 6.4.3. Conclusions for Goodness-of-Fit Both NetProbe and Perfas implementations produce adequate Poisson distributions when according to the Anderson-Darling Goodness-of-Fit at the 5% significance (1-alpha = 0.05, or 95% confidence level). 6.5. Implementation of Statistics for One-way Delay We check which statistics were implemented, and report on those facts, noting that Section 4 of [RFC2680] does not specify the calculations exactly, and gives only some illustrative examples. NetProbe Perfas 4.1. Type-P-One-way-Delay-Packet-Loss-Ave yes yes (this is more commonly referred to as loss ratio) Implementation of Section 4 Statistics We note that implementations refer to this metric as a loss ratio, and this is an area for likely revision of the text to make it more consistent with wide-spread usage. 7. Security Considerations The security considerations that apply to any active measurement of live networks are relevant here as well. See [RFC4656] and [RFC5357]. Ciavattone, et al. Expires January 9, 2013 [Page 22] Internet-Draft Stds Track Tests RFC2680 July 2012 8. IANA Considerations This memo makes no requests of IANA, and the authors hope that IANA personnel will be able to use their valuable time in other worthwhile pursuits. 9. Acknowledgements The authors thank Lars Eggert for his continued encouragement to advance the IPPM metrics during his tenure as AD Advisor. Nicole Kowalski supplied the needed CPE router for the NetProbe side of the test set-up, and graciously managed her testing in spite of issues caused by dual-use of the router. Thanks Nicole! The "NetProbe Team" also acknowledges many useful discussions on statistical interpretation with Ganga Maguluri. 10. References 10.1. Normative References [I-D.ietf-ippm-metrictest] Geib, R., Morton, A., Fardid, R., and A. Steinmitz, "IPPM standard advancement testing", draft-ietf-ippm-metrictest-05 (work in progress), November 2011. [I-D.ietf-ippm-testplan-rfc2679] Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test Plan and Results for Advancing RFC 2679 on the Standards Track", draft-ietf-ippm-testplan-rfc2679-02 (work in progress), June 2012. [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998. [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, September 1999. Ciavattone, et al. Expires January 9, 2013 [Page 23] Internet-Draft Stds Track Tests RFC2680 July 2012 [RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Packet Loss Metric for IPPM", RFC 2680, September 1999. [RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network performance measurement with periodic streams", RFC 3432, November 2002. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC4737] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov, S., and J. Perser, "Packet Reordering Metrics", RFC 4737, November 2006. [RFC4814] Newman, D. and T. Player, "Hash and Stuffing: Overlooked Factors in Network Device Benchmarking", RFC 4814, March 2007. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. [RFC5657] Dusseault, L. and R. Sparks, "Guidance on Interoperation and Implementation Reports for Advancement to Draft Standard", BCP 9, RFC 5657, September 2009. 10.2. Informative References [ADK] Scholz, F. and M. Stephens, "K-sample Anderson-Darling Tests of fit, for continuous and discrete cases", University of Washington, Technical Report No. 81, May 1986. [I-D.morton-ippm-advance-metrics] Morton, A., "Lab Test Results for Advancing Metrics on the Standards Track", draft-morton-ippm-advance-metrics-02 (work in progress), October 2010. [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. [Radgof] Bellosta, C., "ADGofTest: Anderson-Darling Goodness-of-Fit Test. R package version 0.3.", http://cran.r-project.org/ Ciavattone, et al. Expires January 9, 2013 [Page 24] Internet-Draft Stds Track Tests RFC2680 July 2012 web/packages/ADGofTest/index.html, December 2011. [Radk] Scholz, F., "adk: Anderson-Darling K-Sample Test and Combinations of Such Tests. R package version 1.0.", , 2008. [Rtool] R Development Core Team, "R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org/", , 2011. Authors' Addresses Len Ciavattone AT&T Labs 200 Laurel Avenue South Middletown, NJ 07748 USA Phone: +1 732 420 1239 Fax: Email: lencia@att.com URI: Ruediger Geib Deutsche Telekom Heinrich Hertz Str. 3-7 Darmstadt, 64295 Germany Phone: +49 6151 58 12747 Email: Ruediger.Geib@telekom.de Al Morton AT&T Labs 200 Laurel Avenue South Middletown, NJ 07748 USA Phone: +1 732 420 1571 Fax: +1 732 368 1192 Email: acmorton@att.com URI: http://home.comcast.net/~acmacm/ Ciavattone, et al. Expires January 9, 2013 [Page 25] Internet-Draft Stds Track Tests RFC2680 July 2012 Matthias Wieser Technical University Darmstadt Darmstadt, Germany Phone: Email: matthias_michael.wieser@stud.tu-darmstadt.de Ciavattone, et al. Expires January 9, 2013 [Page 26]