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Versions: (draft-morton-ippm-testplan-rfc2680) 00 01 02 03 04 05

Network Working Group                                      L. Ciavattone
Internet-Draft                                                 AT&T Labs
Intended status: Informational                                   R. Geib
Expires: October 5, 2014                                Deutsche Telekom
                                                               A. Morton
                                                               AT&T Labs
                                                               M. Wieser
                                          Technical University Darmstadt
                                                           April 3, 2014


  Test Plan and Results for Advancing RFC 2680 on the Standards Track
                  draft-ietf-ippm-testplan-rfc2680-05

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.

Requirements Language

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

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 5, 2014.




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Copyright Notice

   Copyright (c) 2014 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
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  RFC 2680 Coverage . . . . . . . . . . . . . . . . . . . .   4
   2.  A Definition-centric metric advancement process . . . . . . .   4
   3.  Test configuration  . . . . . . . . . . . . . . . . . . . . .   4
   4.  Error Calibration, RFC 2680 . . . . . . . . . . . . . . . . .   9
     4.1.  Clock Synchronization Calibration . . . . . . . . . . . .   9
     4.2.  Packet Loss Determination Error . . . . . . . . . . . . .  10
   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



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     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 Loss . . . . . .  22
   7.  Conclusions for RFC 2680bis . . . . . . . . . . . . . . . . .  23
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  23
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  24
   11. Appendix - Network Configuration and sample commands  . . . .  24
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  27
     12.2.  Informative References . . . . . . . . . . . . . . . . .  28
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  29

1.  Introduction

   The IETF (specifically the IP Performance Metrics working group, or
   IPPM) has considered how to advance their metrics along the standards
   track since 2001.

   The renewed work effort sought to investigate ways in which the
   measurement variability could be reduced and thereby simplify the
   problem of comparison for equivalence.  As a result, there is
   consensus (captured in [RFC6576]) that equivalent results from
   independent implementations of metric specifications are sufficient
   evidence that the specifications themselves are clear and
   unambiguous; it is the parallel concept of protocol interoperability
   for metric specifications.  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.  It is a
   non-goal to compare the specific implementations themselves.

   The process also permits identification of options described in the
   metric RFC 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] and document the results.

   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-



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   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
   [RFC6808] 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.

   The conclusion reached is that [RFC2680] should be advanced on the
   Standards Track with modifications.  The revised text of RFC 2680bis
   is ready for review [I-D.morton-ippm-2680-bis], but awaits work-in
   progress to update the IPPM Framework [RFC2330].  Therefore, this
   memo documents the information to support [RFC2680] advancement, and
   the approval of RFC2680bis is left for future action.

1.1.  RFC 2680 Coverage

   This plan is intended to cover all critical requirements and sections
   of [RFC2680].

   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 [RFC6576] 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.  This
   memo follows that process.

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 [WIPM]).
   NetProbe uses UDP packets of variable size, and can produce test
   streams with Periodic [RFC3432] or Poisson [RFC2330] sample
   distributions.

   The other metric implementation used was Perfas+ version 3.1,
   developed by Deutsche Telekom [Perfas].  Perfas+ uses UDP unicast



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   packets of variable size (but also supports 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 [RFC6576].












































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           +------------+                                +------------+
           |   Imp 1    |           ,---.                |    Imp 2   |
           +------------+          /     \    +-------+  +------------+
             | 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 (where "Imp #" is the sender and receiver of implementation
   1 or 2, either Perfas+ and NetProbe in this test).  The lower diagram
           shows example flows traveling between two measurement
   implementations.  For simplicity only two flows are shown, and netem
    is omitted (it would appear before or after the Internet, depending
                               on the flow).

                                 Figure 1

   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




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   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 [Fedora] with
   IP forwarding enabled and the "netem" Network emulator as part of the
   Fedora Kernel 2.6.35.11 [netem] loaded and operating.  The standard
   kernel is "tickless" replacing the previous periodic timer (250HZ,
   with 4ms uncertainty) interrupts with on-demand interrupts.
   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.  See the Appendix for more details.

   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" [mii-tool], when 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 was 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 DSCP.  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-<StreamType>-Stream

   With (Section 3.2.  [RFC2680]) metric parameters:




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   + 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 monotonically increasing.  Note
   that T would be a valid parameter of *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.

















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 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  *  *  *

   NetProbe Traceroute

   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 [RFC6808].







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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
   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
   11.5 Mbit/s divided equally among 3 unicast test streams.  We
   concluded 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 misinterpretation 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



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   Section 11.4 of [RFC2330].  This is equivalent to a 95% confidence
   factor.

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 [RFC6576] 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 cross implementation testing.

   4.  If less than ten test streams are available, skip to step 7.



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   5.  Apply the ADK comparison procedures (see Appendix C of [RFC6576])
       and determine the resolution and 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 metric parameters varied for each loss test, and they are listed
   first in each sub-section below.

   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.






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   =======================================

   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.







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   =======================================

   > 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.






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   =======================================

   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




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   different delay conditions, and correctly declare packets arriving in
   excess of the waiting time threshold as lost.

   See Section 2.8.2 of [RFC2680].

   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 1sec 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, 2011 EDT)

   The netem emulator settings added constant delays as specified in the
   procedure above.

6.2.1.  NetProbe results for Loss Threshold

   In NetProbe, the Loss Threshold was 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 were 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




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   packets designated as lost in one of the test streams (with average
   delay = 3.091 sec).

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
   <Time, Delay> 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 10% loss, 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.

   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)






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   =======================================

   > 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].



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   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],
   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, and assign received packet
   timestamps in the measurement application (above UDP layer, see the
   calibration results in Section 4 of [RFC6808] for assessment of
   error).

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:











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   =======================================

   > 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).



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   The statistical summary for two Perfas+ streams is below:

   =======================================

   > 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



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   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
   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 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 Loss

   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-Packet-Loss-Average       yes       yes
        (this is more commonly referred to as loss ratio)


   Implementation of Section 4 Statistics






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   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.  Conclusions for RFC 2680bis

   This memo concludes that [RFC2680] should be advanced on the
   standards track, and recommends the following edits to improve the
   text (which are not deemed significant enough to affect maturity).

   o  Revise Type-P-One-way-Packet-Loss-Ave to Type-P-One-way-Delay-
      Packet-Loss-Ratio .

   o  Regarding implementation of the loss delay threshold (section
      6.2), the assumption of post-processing is compliant, and the text
      of RFC 2680bis should be revised slightly to include this point.

   o  The IETF has reached consensus on guidance for reporting metrics
      in [RFC6703], and this memo should be referenced in RFC2680bis to
      incorporate recent experience where appropriate.

   We note that there are at least two Errata on [RFC2680] and these
   should be processed as part of the editing process.

   We recognize the existence of BCP 170 [RFC6390] providing guidelines
   for development of drafts describing new performance metrics.
   However, the advancement of [RFC2680] represents fine-tuning of long-
   standing specifications based on experience that helped to formulate
   BCP 170, and material that satisfies some of the requirements of
   [RFC6390] can be found in other RFCs, such as the IPPM Framework
   [RFC2330].  Thus, no specific changes to address BCP 170 guidelines
   are recommended for RFC 2680bis.

8.  Security Considerations

   The security considerations that apply to any active measurement of
   live networks are relevant here as well.  See [RFC4656] and
   [RFC5357].

9.  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.







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10.  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.

   Constructive comments and helpful reviews where also provided by Bill
   Cerveny, Joachim Fabini, and Ann Cerveny.

11.  Appendix - Network Configuration and sample commands

   This Appendix provides some background information on the host
   configuration and sample tc commands for the "netem" network
   emulator, as described in Section 3 and Figure 1 in the body of this
   memo.  These details are also applicable to the test plan in
   [RFC6808].

   The host interface and configuration is shown below:

 [system@dell4-4 ~]$ su
 Password:
 [root@dell4-4 system]# service iptables save
 iptables: Saving firewall rules to /etc/sysconfig/iptables:[  OK  ]
 [root@dell4-4 system]# service iptables stop
 iptables: Flushing firewall rules:                         [  OK  ]
 iptables: Setting chains to policy ACCEPT: nat filter      [  OK  ]
 iptables: Unloading modules:                               [  OK  ]
 [root@dell4-4 system]# brctl show
 bridge name     bridge id               STP enabled     interfaces
 virbr0          8000.000000000000       yes
 [root@dell4-4 system]# ifconfig eth1.300 0.0.0.0 promisc up
 [root@dell4-4 system]# ifconfig eth1.400 0.0.0.0 promisc up
 [root@dell4-4 system]# ifconfig eth2.400 0.0.0.0 promisc up
 [root@dell4-4 system]# ifconfig eth2.300 0.0.0.0 promisc up
 [root@dell4-4 system]# brctl addbr br300
 [root@dell4-4 system]# brctl addif br300 eth1.300
 [root@dell4-4 system]# brctl addif br300 eth2.300
 [root@dell4-4 system]# ifconfig br300 up
 [root@dell4-4 system]# brctl addbr br400
 [root@dell4-4 system]# brctl addif br400 eth1.400
 [root@dell4-4 system]# brctl addif br400 eth2.400
 [root@dell4-4 system]# ifconfig br400 up



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 [root@dell4-4 system]# brctl show
 bridge name     bridge id               STP enabled     interfaces
 br300           8000.0002b3109b8a       no              eth1.300
                                                         eth2.300
 br400           8000.0002b3109b8a       no              eth1.400
                                                         eth2.400
 virbr0          8000.000000000000       yes

 [root@dell4-4 system]# brctl showmacs br300
 port no mac addr                is local?       ageing timer
   2     00:02:b3:10:9b:8a       yes                0.00
   1     00:02:b3:10:9b:99       yes                0.00
   1     00:02:b3:c4:c9:7a       no                 0.52
   2     00:02:b3:cf:02:c6       no                 0.52
   2     00:0b:5f:54:de:81       no                 0.01
 [root@dell4-4 system]# brctl showmacs br400
 port no mac addr                is local?       ageing timer
   2     00:02:b3:10:9b:8a       yes                0.00
   1     00:02:b3:10:9b:99       yes                0.00
   2     00:02:b3:c4:c9:7a       no                 0.60
   1     00:02:b3:cf:02:c6       no                 0.42
   2     00:0b:5f:54:de:81       no                 0.33
 [root@dell4-4 system]# tc qdisc add dev eth1.300 root netem delay 100ms

 [root@dell4-4 system]# ifconfig eth1.200 0.0.0.0 promisc up
 [root@dell4-4 system]# vconfig add eth1 100
 Added VLAN with VID == 100 to IF -:eth1:-

 [root@dell4-4 system]# ifconfig eth1.100 0.0.0.0 promisc up

 [root@dell4-4 system]# vconfig add eth2 100
 Added VLAN with VID == 100 to IF -:eth2:-

 [root@dell4-4 system]# ifconfig eth2.100 0.0.0.0 promisc up
 [root@dell4-4 system]# ifconfig eth2.200 0.0.0.0 promisc up
 [root@dell4-4 system]# brctl addbr br100
 [root@dell4-4 system]# brctl addif br100 eth1.100
 [root@dell4-4 system]# brctl addif br100 eth2.100
 [root@dell4-4 system]# ifconfig br100 up
 [root@dell4-4 system]# brctl addbr br200
 [root@dell4-4 system]# brctl addif br200 eth1.200
 [root@dell4-4 system]# brctl addif br200 eth2.200
 [root@dell4-4 system]# ifconfig br200 up
 [root@dell4-4 system]# brctl show
 bridge name     bridge id               STP enabled     interfaces
 br100           8000.0002b3109b8a       no              eth1.100
                                                         eth2.100
 br200           8000.0002b3109b8a       no              eth1.200



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                                                         eth2.200
 br300           8000.0002b3109b8a       no              eth1.300
                                                         eth2.300
 br400           8000.0002b3109b8a       no              eth1.400
                                                         eth2.400
 virbr0          8000.000000000000       yes
 [root@dell4-4 system]# brctl showmacs br100
 port no mac addr                is local?       ageing timer
   2     00:02:b3:10:9b:8a       yes                0.00
   1     00:02:b3:10:9b:99       yes                0.00
   1     00:0a:e4:83:89:07       no                 0.19
   2     00:0b:5f:54:de:81       no                 0.91
   2     00:e0:ed:0f:72:86       no                 1.28
 [root@dell4-4 system]# brctl showmacs br200
 port no mac addr                is local?       ageing timer
   2     00:02:b3:10:9b:8a       yes                0.00
   1     00:02:b3:10:9b:99       yes                0.00
   2     00:0a:e4:83:89:07       no                 1.14
   2     00:0b:5f:54:de:81       no                 1.87
   1     00:e0:ed:0f:72:86       no                 0.24
 [root@dell4-4 system]# tc qdisc add dev eth1.100 root netem delay 100ms
 [root@dell4-4 system]#

 ======================================================================

   Some sample tc command lines controlling netem and its impairments
   are given below.

   tc qdisc add dev eth1.100 root netem loss 0%
   tc qdisc add dev eth1.200 root netem loss 0%
   tc qdisc add dev eth1.300 root netem loss 0%
   tc qdisc add dev eth1.400 root netem loss 0%

   Add delay and delay variation:
   tc qdisc change dev eth1.100 root netem delay 100ms 50ms
   tc qdisc change dev eth1.200 root netem delay 100ms 50ms
   tc qdisc change dev eth1.300 root netem delay 100ms 50ms
   tc qdisc change dev eth1.400 root netem delay 100ms 50ms

   Add delay, delay variation, and loss:
   tc qdisc change dev eth1 root netem delay 2000ms 1000ms loss 10%

   =====================================================================








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12.  References

12.1.  Normative References

   [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.

   [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.

   [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.

   [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
              Performance Metric Development", BCP 170, RFC 6390,
              October 2011.

   [RFC6576]  Geib, R., Morton, A., Fardid, R., and A. Steinmitz, "IP
              Performance Metrics (IPPM) Standard Advancement Testing",
              BCP 176, RFC 6576, March 2012.

   [RFC6703]  Morton, A., Ramachandran, G., and G. Maguluri, "Reporting
              IP Network Performance Metrics: Different Points of View",
              RFC 6703, August 2012.



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   [RFC6808]  Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test
              Plan and Results Supporting Advancement of RFC 2679 on the
              Standards Track", RFC 6808, December 2012.

12.2.  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.

   [Fedora]   "http://fedoraproject.org/", .

   [I-D.morton-ippm-2680-bis]
              Almes, G., Zekauskas, M., and A. Morton, "A One-Way Loss
              Metric for IPPM", draft-morton-ippm-2680-bis-02 (work in
              progress), February 2014.

   [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.

   [Perfas]   Heidemann, C., "Qualitaet in IP-Netzen Messverfahren",
              published by ITG Fachgruppe, 2nd meeting 5.2.3 (NGN)
              http://www.itg523.de/oeffentlich/01nov/
              Heidemann_QOS_Messverfahren.pdf , November 2001.

   [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/
              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.

   [WIPM]     "AT&T Global IP Network",
              http://ipnetwork.bgtmo.ip.att.net/pws/index.html, 2012.





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   [mii-tool]
              "http://man7.org/linux/man-pages/man8/mii-tool.8.html", .

   [netem]    "http://www.linuxfoundation.org/collaborate/workgroups/
              networking/netem", .

Authors' Addresses

   Len Ciavattone
   AT&T Labs
   200 Laurel Avenue South
   Middletown, NJ  07748
   USA

   Phone: +1 732 420 1239
   Email: lencia@att.com


   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/


   Matthias Wieser
   Technical University Darmstadt
   Darmstadt
   Germany

   Email: matthias_michael.wieser@stud.tu-darmstadt.de





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