Internet Engineering Task Force                      Jan Novak
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Informational
Expires: 13 June, 15 October, 2011                                  15 April 2011                                  13 December 2010

         IP Flow Information Accounting and Export Benchmarking
                               Methodology
                  draft-ietf-bmwg-ipflow-meth-00.txt
                  draft-ietf-bmwg-ipflow-meth-01.txt

Abstract

   This document provides methodology and framework for quantifying
   performance impact of monitoring of IP flows on a network device and
   export of this information to a collector. It identifies the rate at
   which the IP flows are created, expired and successfully exported as the
   a new performance metric. metric in combination with traditional throughput.
   The metric is only applicable to the devices compliant with the
   Architecture for IP Flow Information Export [RFC5470].

Status of this Memo

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Conventions used in this document

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].

Table of Contents

   1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3
   2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
      2.1 Existing Terminology. . . . . . . . . . . . . . . . . . . 4
      2.2 New Terminology . . . . . . . . . . . . . . . . . . . . . 4
   3. Flow Monitoring Performance Metric. . . . . . . . . . . . . . 6
      3.1 The Definition. . . . . . . . . . . . . . . . . . . . . . 6
      3.2 Device Applicability. . . . . . . . . . . . . . . . . . . 6
      3.3 Measurement Concept . . . . . . . . . . . . . . . . . . . 7
      3.4 The Measurement Procedure Overview. . . . . . . . . . . . 8
      3.5 Software Platforms. . . . . . . . . . . . . . . . . . . . 9
      3.6 Hardware Platforms. . . . . . . . . . . . . . . . . . . . 9
   4. Measurement Set Up Up. . . . . . . . . . . . . . . . . . . . . . 10 9
      4.1 Measurement Topology Topology. . . . . . . . . . . . . . . . . . . 10 9
      4.2 Base DUT Set Up. . . . . . . . . . . . . . . . . . . . . 11 10
      4.3 Flow Monitoring Configuration. . . . . . . . . . . . . . 11
      4.4 Collector. . . . . . . . . . . . . . . . . . . . . . . . 15 14
      4.5 Packet Sampling. . . . . . . . . . . . . . . . . . . . . 15
      4.6 Frame Formats. . . . . . . . . . . . . . . . . . . . . . 16 15
      4.7 Frame Sizes. . . . . . . . . . . . . . . . . . . . . . . 16
      4.8 Flow Export Data Packet Sizes. . . . . . . . . . . . . . 16
      4.9 Illustrative Test Set-up Examples. . . . . . . . . . . . 17 16
   5. Flow Monitoring Throughput Measurement Methodology . . . . . 18
      5.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 18
      5.2 Traffic Configuration. . . . . . . . . . . . . . . . . . 19
      5.3 Cache Population . . . . . . . . . . . . . . . . . . . . 20 19
      5.4 Measurement Time Interval. . . . . . . . . . . . . . . . 20
      5.5 Flow Export Rate Measurement . . . . . . . . . . . . . . 21
      5.6 The Measurement Procedure. . . . . . . . . . . . . . . . 22 21
   6. RFC2544 Measurements . . . . . . . . . . . . . . . . . . . . 22
      6.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 23
      6.2 Measurements With the Flow Monitoring Throughput Set-up. 24 23
      6.3 Measurements With Fixed Flow Expiration Rate . . . . . . 24 23
      6.4 Measurements With Single Traffic Component . . . . . . . 24
      6.5 Measurements With Two Traffic Components . . . . . . . . 25 24
   7. Flow Monitoring Accuracy . . . . . . . . . . . . . . . . . . 25
   8. Evaluating Flow Monitoring Applicability . . . . . . . . . . 26 25
   9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 27 26
   11. Security Considerations . . . . . . . . . . . . . . . . . . 27 26
   12. References. . . . . . . . . . . . . . . . . . . . . . . . . 27 26
      12.1 Normative References. . . . . . . . . . . . . . . . . . 27 26
      12.2 Informative References. . . . . . . . . . . . . . . . . 27
   Appendix A: Recommended Report Format . . . . . . . . . . . . . . . . . . . 30 28

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   Appendix B: Miscellaneous Tests . . . . . . . . . . . . . . . . 31 29
      B.1 DUT Under Traffic Load . . . . . . . . . . . . . . . . . 31 29
      B.2 In-band Flow Export. . . . . . . . . . . . . . . . . . . 31 29
      B.3 Variable Packet Rate . . . . . . . . . . . . . . . . . . 32 30
      B.4 Bursty Traffic . . . . . . . . . . . . . . . . . . . . . 32 30
      B.5 Various Flow Monitoring Configurations . . . . . . . . . 32 30
      B.6 Tests With Bidirectional Traffic . . . . . . . . . . . . 33 31
      B.7 Instantaneous Flow Export Rate . . . . . . . . . . . . . 33 31

1.  Introduction

    Monitoring of IP flows (Flow monitoring) on network devices is a
    widely used deployed application that has numerous uses in both service
    provider and enterprise segments as detailed in the Requirements for
    IP Flow Information Export [RFC3917]. This document intends to
    provide provides a
    methodology for measuring Flow monitoring performance and
    provide so that
    network operators have a framework for considering its measurement
    impact to on the network and network equipment.

    Flow monitoring is defined in the Architecture for IP Flow
    Information Export [RFC5470] and related IPFIX documents.

    What is the cost of enabling the IP Flow monitoring and export to a
    collector ? This is a the basic question that this document tries methodology is
    designed to answer.

    This document goal is a series of methodology specifications for
    the
    monitoring measurement of Flow monitoring performance, in a way that is
    comparable amongst various implementations, various platforms, and
    vendors.
    vendor's devices.

    Since Flow monitoring will in most cases run on network devices also
    forwarding packets, the methodology for RFC2544 measurements (with
    IPv6 and MPLS specifics defined in [RFC5180] and [RFC5695]
    respectively) in the presence of Flow monitoring is also proposed employed
    here.

    The most significant performance parameter in terms of performance, is the rate at which IP
    flows are created and expired in the network devices memory and
    exported to a collector. Therefore, this document focuses on a
    methodology on how to measure the maximum IP flow rate that a
    network device can sustain without impacting the forwarding plane,
    without losing any IP flow information, and without compromising the
    IP flow accuracy.

    [RFC2544], [RFC5180] and [RFC5695] specify benchmarking of network
    devices forwarding IPv4, IPv6 and MPLS [RFC3031] traffic,
    respectively. Even if this document specifies the Flow monitoring
    methodology for network devices forwarding IPv4, IPv6, and MPLS, the The methodology specified here stays the same for any
    traffic type. The only restriction is the actual Flow monitoring
    support for the particular traffic type.

    A variety of different network device architectures exist that are
    capable of Flow monitoring support. and export. As such, this document does not
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    not attempt to list the various white box variables (CPU load,
    memory utilization, TCAM utilization etc) that could be gathered as
    they do always help in comparison evaluations. A better more complete
    understanding of the stress points of a particular device can be
    attained by using this deeper internal information gathering and a the tester may MAY choose
    to gather additional this information during the measurement iterations.

2.  Terminology

    The terminology used in this document is mostly based on [RFC5470],
    [RFC2285] and [RFC1242] as summarised in the section 2.1. The only
    new terms needed by for this document methodology are defined in the following
    section 2.2.

2.1 Existing Terminology

    Device Under Test (DUT)   [RFC2285, section 3.1.1]

    Flow                      [RFC5470, section 2]

    Flow Key                  [RFC5470, section 2]

    Flow Record               [RFC5470, section 2]

    Observation Point         [RFC5470, section 2]

    Metering Process          [RFC5470, section 2]

    Exporting Process         [RFC5470, section 2]

    Exporter                  [RFC5470, section 2]

    Collector                 [RFC5470, section 2]

    Control Information       [RFC5470, section 2]

    Data Stream               [RFC5470, section 2]

    Flow Expiration           [RFC5470, section 5.1.1]

    Flow Export               [RFC5470, section 5.1.2]

    Throughput                [RFC1242, section 3.17]

    Packet Sampling           [RFC5476, section 2]

2.2 New Terminology

2.2.1 Cache

   Definition:
      Memory area held and dedicated by the DUT to store Flow Record
      information prior Flow Expiration
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2.2.2 Cache Size

   Definition:
      The size of the Cache in terms of how many entries of Flow
      Records the Cache can hold

   Discussion:
      This term is typically represented as a configurable option in
      the particular Flow monitoring implementation. Its highest value
      will depend on the memory available in the network device.

   Measurement units:
      Number of Flow Records

2.2.3 Active Timeout

   Definition:
      For long-running Flows, the time interval after which the Metering
      Process expires a Flow Record from the Cache so that only regular
      Flow updates are exported.

   Discussion:
      This term is typically represented as a configurable option in the
      particular Flow monitoring implementation. See section 5.1.1 of
      [RFC5470] for more detailed discussion.

      As long-running

      Flows are considered Flows which long-running when they last longer than
      several multiples of the Active Timeout or contain larger amount
      of packets (in the case of Active Timeout is zero) than usual for
      a single transaction based Flows, in the order of tens of packets
      and higher.

   Measurement units:
      Seconds

2.2.4 Inactive Timeout

   Definition:
      The time interval after which used by the Metering Process expires to expire a Flow
      Record from the Cache if Cache, when no more packets belonging to that
      specific Flow are seen. observed during the interval.

   Discussion:
      This term is typically represented as a configurable option in the
      particular Flow monitoring implementation. See section 5.1.1 of
      [RFC5470] for more detailed discussion.

   Measurement units:
      Seconds

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2.2.5 Flow Export Rate

   Definition:
      Number of Flow Records that expire from the Cache (as defined by
      the Flow Expiration term) and are exported to the Collector within
      a measurement time interval.

      The measured Flow Export Rate MUST include BOTH the Data Stream
      and the Control Information, as defined in section 2 of [RFC5470].

   Discussion:

      The Flow Export Rate is measured using Flow Export data observed
      at the Collector by counting the exported Flow Records during the
      measurement time interval (see section 5.4). The value obtained is
      an average of the instantaneous export rates observed during the
      measurement time interval. The smallest possible measurement
      interval (if attempting to measure rather nearly instantaneous export
      rate rather than average export rate on the DUT) is limited by the
      export capabilities of the particular Flow monitoring
      implementation.

   Measurement units:
      Number of Flow Records per second

3.  Flow Monitoring Performance Metric

3.1 The Definition

   Flow Monitoring Throughput

   Definition:
      The maximum Flow Export Rate the DUT can sustain without losing a
      single Flow Record expired from the Cache and Cache. Additionally, for the
      packet forwarding devices, also the maximum Flow Export Rate the
      DUT can sustain without dropping any packets in the Forwarding Plane
      (see Figure 1).

   Measurement units:
      Number of Flow Records per second

3.2 Device Applicability

   The Flow monitoring performance metric is applicable to network
   devices that implement RFC5470 [RFC5470] architecture. These devices
   can be network packet forwarding devices or appliances which analyse analyze
   the traffic but do not forward traffic (probes, sniffers,
   replicators).

   The Flow monitoring Collector performance metric is not applicable to the
   Collector since it does not implement the RFC5470 architecture.

Novak out of scope of this document.

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3.3 Measurement Concept

   The traffic in the Figure 1 represents the test traffic sent to the
   DUT and forwarded by the DUT. When testing devices which do not act
   as network packet forwarding devices (appliances - probes, sniffers,
   replicators) the forwarding plane is simply an Observation Point as
   defined in section 2 of [RFC5470]. The RFC2544 Throughput of such
   devices will simply be always zero and the only applicable
   performance metrics is Flow Monitoring Throughput.

   The Flow monitoring enabled (see section 4.3) on the DUT (and
   represented in the Figure 1 by the Flow Monitoring Plane) uses the
   traffic information provided by the Forwarding Plane and configured
   Flow Keys to create the Flow Records representing the traffic
   forwarded (or observed) by the DUT. The Flow Records are stored in
   the Flow monitoring Cache and expired from there depending on the
   Cache configuration (Active and Inactive Timeouts, number of Flow
   Records and the Cache Size) and the traffic pattern. The expired Flow
   Records are exported from the DUT to the Collector (see Figure 2 in
   section 4).

                 +--------------------------+
                 |IPFIX|Sflow|Netflow|Others|
                 +--------------------------+

                 +------------------------- +
                 | IPFIX | Netflow | Others |
                 +------------------------- +
                 |            ^             |
                 |            ^             |
                 |       Flow Export        |
                 |            ^             |
                 |            ^             |
                 |     +-------------+      |
                 |     |    Flow     |      |
                 |     | Monitoring  |      |
                 |     |   Plane     |      |
                 |     +-------------+      |
                 |            ^             |
                 |            ^             |
                 |     traffic information  |
                 |            ^             |
                 |            ^             |
                 |     +-------------+      |
                 |     |             |      |
      traffic ---|---->| Forwarding  |------|---->
                 |     |    Plane    |      |
                 |     +-------------+      |
                 |                          |
                 |           DUT            |
                 +--------------------------+
                 +------------------------- +

   Figure 1. The functional block diagram of the DUT

   The Forwarding Plane and Flow Monitoring Plane represent two separate
   functional blocks, each with it's own performance capability. The
   Forwarding Plane handles user data packets and is fully characterised
   by the metrics defined by [RFC2544].
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   The Flow Monitoring Plane handles Flow Records which reflect the
   forwarded traffic. The metric that measures the Flow Monitoring Plane
   performance is Flow Export Rate. Rate, and the benchmark is the Flow
   Monitoring Throughput.

3.4 The Measurement Procedure Overview

   The measurement procedure is fully specified in sections 4, 5 and 6.
   This section provides an overview of principles for the measurements.

   The basic measurement procedure of performance characteristics of a
   DUT with Flow monitoring enabled is a conventional Throughput
   measurement using a search algorithm to determine the maximum packet
   rate at which none of the offered packets and corresponding Flow
   Record
   Records are dropped by the DUT as described in [RFC1242] and section
   26.1 of [RFC2544].

   DUT

   The Device Under Test (DUT) with Flow monitoring enabled contains two
   functional blocks which need to be measured using characteristics
   applicable to one or the
   other block both blocks  (see Figure 1). See sections 3.4.1
   and 3.4.2 for further discussion.

   On one hand the Flow Monitoring Plane and Forwarding Plane (see
   Figure 1) need to be looked at as two independent blocks (and the
   performance of each of them measured independently) but on the other
   hand when measuring the performance of one of them the status and
   conditions
   performance of the other one must MUST be known and monitored. benchmarked when both are
   present.

3.4.1 Flow Monitoring Plane Performance Measurement

   The Flow Monitoring Throughput MUST be (and can only be) measured
   with one packet per Flow as specified in the section 5. This traffic
   type represents the most aggressive demanding traffic from the Flow monitoring
   point of view and will exercise the Flow Monitoring Plane (see Figure
   1) of the DUT most. The exit criteria for the Flow Monitoring
   Throughput measurement are one of the following (e.g. if any of the
   conditions is reached):

   a. The Flow Export Rate at which the DUT starts to drop Flow Records
      or the Flow information gets corrupted
   b. The Flow Export Rate at which the Forwarding Plane starts to drop
      or corrupt packets (if the Forwarding Plane is present)

3.4.2 Forwarding Plane Performance Measurement

   The Forwarding Plane (see Figure 1) performance metrics are fully
   specified by [RFC2544] and MUST be measured accordingly. A detailed
   traffic analysis (see below) with relation to Flow monitoring MUST be
   performed prior of any RFC2544 measurements. Mainly the Flow Export
   Rate caused by the test traffic during an RFC2544 measurement MUST
   be known and noted. reported.

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   The required traffic analysis mainly involves the following:

   a. Which packet header parameters are incremented or changed during
      traffic generation
   b. Which Flow Keys the Flow monitoring configuration uses to generate
      Flow Records

   The RFC2544 performance metrics can be measured in one of the two three
   modes:

   a. As a baseline of forwarding performance without Flow monitoring
   b. At certain level of Flow monitoring activity specified by a Flow
      Expiration Rate lower than Flow Monitoring Throughput

      b.
   c. At the maximum of Flow monitoring performance, e.g. using traffic
      conditions representing a measurement of Flow Monitoring
      Throughput

   The details how to setup the above mentioned measurement modes are mode in
   the section 6.

3.5 Software Platforms

   On purely software based DUTs with no hardware assisted
   functionalities, the measured Flow Monitoring Throughput will be
   numerically equal to the RFC2544 Throughput. This is due to the fact
   that the DUT resources are fully shared between the two functional
   blocks (see Figure 1). At the maximum point of the performance
   measurement the DUT will become short of resources to process packets
   and since every packet a. represents in the Flow Monitoring an
   ordinary Throughput measurement also one Flow, at the moment one packet is lost, one Flow
   is lost.

   On a software platform the Flow Monitoring Plane and Forwarding Plane
   are functionally independent but their performance is coupled
   together due to the shared resources for packet and Flow Record
   processing.

3.6 Hardware Platforms

   On a hardware based DUT, where packet forwarding and possibly other
   functions are assisted by specialised hardware, the Flow Monitoring
   Plane and Forwarding Plane may not only be functionally but also
   performance wise independent (if the two functional blocks do not
   share any resources). specified in RFC2544. The possible architectures of hardware based DUTs can be so diverse
   which makes it impossible details how
   to provide any advice on expected DUT
   behaviour. The Flow Monitoring Plane and Forwarding Plane must be
   treated as two independent blocks and measured independently. The
   most typical outcome of a measurement here will be totally
   independent values of Flow Monitoring Throughput and RFC2544.

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   Throughput depending on which part of setup the functionality is
   implemented measurements in hardware points b. and which c. are in software. the section 6.

4. Measurement Set Up

   This section concentrates on the set-up of all components necessary
   to perform Flow monitoring performance measuring. measurement. The recommended
   reporting format can be found in Appendix A.

4.1 Measurement Topology

   The measurement topology described in this section is applicable only
   to the measurements with packet forwarding network devices. The
   possible architectures and implementation of the traffic monitoring
   appliances (see section 3.2) are too various to be covered in this
   document. Generally, those appliances instead of the Forwarding Plane
   will have some kind of feed (an optical splitter, an interface
   sniffing traffic on a shared media or an internal channel on the DUT
   providing a copy of the traffic) providing the information about the
   traffic necessary for Flow monitoring analysis. The measurement
   topology then needs to be adjusted to the appliance architecture.

   The measurement set-up is identical to the one used by [RFC2544],
   with the addition of a Collector to analyse analyze the Flow Export:

                             +-----------+
                             |           |
                             | Collector |
                             |           |
                             |Flow Record|
                             | analysis  |
                             |           |
                             +-----------+
                                   ^
                                   | Flow Export
                                   |
                                   | Export Interface
         +--------+         +-------------+          +----------+
         |        |         |             |          |          |
         |        |      (*)|             |          | receiver |
         | sender |-------->|     DUT     |--------->|          |
         |        |         |             |          | traffic  |
         |        |         |             |          | analysis |
         +--------+         +-------------+          +----------+ (see
   Figure 2 Measurement topology with unidirectional traffic 2).

   In the measurement topology with unidirectional traffic, the traffic
   is generated from the sender to the receiver, where the received
   traffic is analyzed to check it is identical to the generated
   traffic.

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   The ideal way to implement the measurement is using one traffic
   generator (device providing the sender and receiver capabilities)
   with a sending port and a receiving port.  This allows for an easy
   check if all the traffic sent by the sender was transmitted by the was transmitted by the
   DUT and received at the receiver.
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                             +-----------+
                             |           |
                             | Collector |
                             |           |
                             |Flow Record|
                             | analysis  |
                             |           |
                             +-----------+
                                   ^
                                   | Flow Export
                                   |
                                   | Export Interface
         +--------+         +-------------+          +----------+
         |        |         |             |          |          |
         |        |      (*)|             |          | receiver |
         | sender |-------->|     DUT and received at the receiver.     |--------->|          |
         |        |         |             |          | traffic  |
         |        |         |             |          | analysis |
         +--------+         +-------------+          +----------+

   Figure 2 Measurement topology with unidirectional traffic

   The export interface (connecting the Collector) MUST NOT be used for
   forwarding the test traffic but only for the Flow Export data
   containing the Flow Records. In all measurements, the export
   interface MUST have enough bandwidth to transmit Flow Export data
   without congestion. In other words, the export interface MUST NOT be
   a bottleneck during the measurement.

   Note that more complex topologies might be required. For example, if
   the effects of enabling Flow monitoring on several interfaces are of
   concern or the media maximum speed is less than the DUT throughput,
   the topology can be expanded with several input and output ports.
   However, the topology MUST be clearly written in the measurement
   report.

4.2 Base Baseline DUT Set Up

   The base baseline DUT set-up and the way the set-up is reported in the
   measurement results is fully specified in Section 7 of [RFC2544].

   The base DUT configuration might include other features like packet
   filters or quality of service on the input and/or output interfaces
   if there is the need to study Flow monitoring in the presence of
   those features. The Flow monitoring measurement procedures do not
   change in this case. Consideration needs to be made when evaluating
   measurements results to take into account the possible change of
   packets rates offered to the DUT and Flow monitoring after
   application of the features to the configuration. Any such feature
   configuration MUST be part of the measurement report.

   The DUT export interface (see Figure 2) MUST be configured with
   sufficient output buffers to avoid dropping the Flow Export data due
   to a simple lack of resources in the interface hardware.
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4.3 Flow Monitoring Configuration

   This section covers all the aspects of the Flow monitoring
   configuration necessary on the DUT in order to perform Flow
   monitoring performance measurement. The necessary configuration has
   number of components (see [RFC5470]), namely Observation Points,
   Metering Process and Exporting Process as detailed below.

   The DUT MUST support Flow monitoring architecture as specified by
   [RFC5470]. The DUT SHOULD support IPFIX [RFC5101] for easier results
   comparison.

   The DUT configuration and any existing Cache MUST be erased before
   application of any new configuration for the currently executed
   measurement.

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   4.3.1 Observation Points

      The Observation Points specify the interfaces and direction where
      the Flow monitoring traffic analysis is performed.

      The (*) in Figure 2 designates the Observation Points in the
      default configuration. Other DUT Observation Points might be
      configured depending on the specific measurement needs as follows:

         a. ingress port/ports(s) only
         b. egress port(s) /ports only
         c. both ingress and egress

      Generally, the placement of Observation Points depends upon the
      position of the DUT in the deployed network and the purpose of
      Flow monitoring deployment. See [RFC3917] for detailed discussion.
      The measurement procedures are otherwise same for all these
      possible configurations.

      In the case when both ingress and egress Flow monitoring is
      enabled on one DUT the results analysis needs to take into account
      that each Flow will be represented in the DUT Cache by two Flow
      Records (one for each direction) and therefore also the Flow
      Export will contain those two Flow Records.

      If more than one Observation Point for one direction is defined on
      the DUT the traffic passing through each of the Observation Points
      MUST be configured in such a way that it creates Flows and Flow
      Records which do not overlap, e.g. each packet (or set of packets
      if measuring with more than one packet per Flow) sent to the DUT
      on different ports still creates one unique Flow Record.

      The specific Observation Points and associated monitoring
      direction MUST be included as part of the report of the results.

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   4.3.2 Metering Process

      Metering Process MUST be enabled in order to create the Cache in
      the DUT and configure the Cache related parameters.

      Cache Size available to the DUT operation MUST be known and taken
      into account when designing the measurement as specified in the
      section 5.

      Inactive and Active Timeouts MUST be known and taken into account
      when designing the measurement as specified in the section 5.

      The Cache Size, the Inactive and Active Timeouts, and if present,
      the specific Packet Sampling techniques and associated parameters
      MUST be included as part of the results report.

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   4.3.3 Exporting Process

      Exporting Process MUST be configured in order to export the Flow
      Record data to the Collector.

      Exporting Process MUST be configured in such a way that all Flow
      Records from all configured Observation Points are exported
      towards the Collector, after the expiration policy composed of
      the Inactive and Active Timeouts and Cache Size.

      The Exporting Process SHOULD be configured with IPFIX [RFC5101] as
      the protocol to use to format the Flow Export data. If the Flow
      monitoring implementation does not support it, proprietary
      protocols MAY be used.

      Various Flow monitoring implementations might use different
      default values regarding the export of Control Information. The
      Flow Export corresponding to Control Information SHOULD be
      analysed
      analyzed and reported as a separate item on the measurement
      report. Preferably, the export of Control Information SHOULD
      always be configured same.

      IPFIX documents [RFC5101] in section 10 and [RFC5470] in section
      8.1 discuss the possibility to deploy various transport layer
      protocols to deliver Flow Export data from the DUT to the
      Collector. The selected protocol MUST be included in the
      measurement report. Only benchmarks with same transport layer
      protocol SHOULD be compared. If the Flow monitoring implementation
      allows to use all of UDP, TCP and SCTP as the transport layer
      protocols, each of the protocols SHOULD be measured in a separate
      measurement run.

      If reliable transport protocol is used for the transmission of the
      Flow Export data from DUT, the configuration of the transport
      session MUST allow for non-blocking data transmission. An example
      of parameters to look at would be TCP window size or maximum
      segment size (MSS).

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   4.3.4 Flow Records

      Flow Record defines the traffic parameters which Flow monitoring
      uses to analyse analyze the traffic and MUST be configured in order to
      perform the analysis. The Flow Key fields of the Flow Record
      define the traffic parameters which will be used to create new
      Flow Records in the DUT Cache.

      The Flow Record definition is implementation specific. A Flow
      monitoring implementation might allow for only fixed Flow Record
      definition, based on the most common IP parameters in the IPv4 or
      IPv6 headers - like source and destination IP addresses, IP
      protocol numbers or transport level port numbers. Another
      implementation might allow the user to actually define his own
      completely arbitrary Flow Record to monitor the traffic. The
      requirement for the measurements defined in this document is only
      the need for a large number of Flow Records in the Cache. The Flow
      Keys needed to achieve that will typically be source and
      destinations IP addresses and transport level port numbers.

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      Recommended full IPv4, IPv6 or MPLS Flow Record:
         Flow Keys
                Source IP address
                Destination IP address
                MPLS label (for MPLS traffic type only)
                Transport layer source port
                Transport layer destination port
                IP protocol number (IPv6 next header)
                IP type of service (IPv6 traffic class)

        Other fields
                Packet counter
                Byte counter

      If the Flow monitoring allows for user defined Flow Records the
      minimal Flow Record configurations allowing to achieve large
      numbers of Cache entries for example are:

         Flow Keys
                Source IP address
                Destination IP address

         Other fields
                Packet counter

      or:

         Flow Key fields
                Transport layer source port
                Transport layer destination port

         Other fields
                Packet counter

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      The Flow Record configuration MUST be clearly noted in the
      measurement report. The Flow Monitoring Throughput measurements on
      different DUTs or different Flow monitoring implementations can
      and MUST be compared only for exactly same Flow Record
      configuration.

4.3.5 MPLS Measurement Specifics

    The Flow Record configuration for measurements with MPLS
    encapsulated traffic SHOULD contain MPLS label or any other field
    which is part of the MPLS header.

    The DUT Cache SHOULD be checked prior the performance measurement to
    contain the correct MPLS related information.

    The captured export data at the Collector SHOULD be checked for the
    presence of MPLS labels or the monitored MPLS parameters. MPLS
    forwarding performance document [RFC5695] specifies number of

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    possible MPLS label operations to test. The Observation Points
    SHOULD be placed on all the DUT test interfaces where the particular
    MPLS label operation takes place. The performance measurements
    SHOULD be performed with only one MPLS label operation at the time.

    The DUT SHOULD be configured in such a way, that all the traffic is
    subject of the measured MPLS label operation.

4.4 Collector

   The Collector is needed in order to capture the Flow Export data
   which allow the Flow Monitoring Throughput to be measured.

   The Collector can be used as exclusively capture device providing
   just hexadecimal format of the Flow Export data. In such a case it
   does not need to have any additional Flow Export decoding
   capabilities.

   However if the Collector is also used to decode the Flow Export data
   then it SHOULD support IPFIX [RFC5101] for easier results analysis.
   If proprietary Flow Export is deployed, the Collector MUST support it
   otherwise the Flow Export data analysis is not possible.

   The Collector MUST be capable to capture at the full rate the export
   packets are sent from the DUT without losing any of them. In the case of
   the use of reliable transport protocols (see also section 4.3.3) to
   transmit Flow Export data, the Collector MUST have sufficient
   resources to guarantee non-blocking data transmission on the
   transport layer session.

   During the analysis, the Flow Export data needs to be decoded and the
   received Flow Records counted.

   The Collector SHOULD support Ethernet type of interface to connect to
   the DUT but any media which allows data capturing and analysis can be
   used.
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   The capture buffer MUST be cleared at the beginning of each
   measurement.

4.5 Packet Sampling

   A Flow monitoring implementation might provide the capability to
   analyse
   analyze the Flows after Packet Sampling is performed. The possible
   procedures and ways of Packet Sampling are described in [RFC5476]
   and [RFC5475] and only those SHOULD be used for measurements.

   If the DUT is configured with one of the sampling techniques as
   specified in [RFC5475] the measurement report MUST include this
   sampling technique along with its parameters. The presence of the
   configured sampling technique on the DUT and its parameters SHOULD be
   verified in the Flow Export data as received on the Collector.

   Packet Sampling will affect the measured Flow Export Rate. If
   systematic sampling (see section 6.5 of [RFC5476]) is in use, the
   Flow Export Rate can be derived from the packet rates (see section 5

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   of this document) using the configured sampling parameters. If random
   sampling is in use the Flow Export Rate can be derived from the
   traffic rates as obtained on the receiver side of the traffic
   generator, provided that packet losses can be excluded by monitoring
   the DUT forwarding statistics.

   If measurements are performed with Flows containing more than one
   packet per Flow (see section 6.4 of this document) the sampling ratio
   SHOULD always be higher than the number of packets in the Flows (for
   small number of packets per Flow). This significantly decreases the
   probability of erasing a whole Flow to a minimum and the measured
   Flow Expiration Rate stays unaffected by sampling.

   If Flow accuracy analysis (see section 7) is performed, the results
   will be always affected by Packet Sampling and the complete check of
   data cannot be performed.

   This document does not intend to study the effects of Packet Sampling
   itself on the network devices but Packet Sampling can simply be
   applied as part of the Flow monitoring configuration on the DUT and
   perform the measurements as specified in the later sections.
   Consideration needs to be made when evaluating measurements results
   to take into account the change of packet rates offered to the DUT
   and especially to Flow monitoring after Packet Sampling is applied.

4.6 Frame Formats

   Flow monitoring itself is not dependent in any way on the media used
   on the input and output ports. Any media can be used as supported by
   the DUT and the test equipment.

   The most common transmission media and corresponding frame formats
   (Ethernet, Packet over Sonet) SONET) for IPv4, IPv6 and MPLS traffic are
   specified within [RFC2544], [RFC5180] and [RFC5695].

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4.7 Frame Sizes

   Frame sizes of the traffic analyzed by the to use are specified in
   [RFC2544] section 9 for Ethernet type interfaces (64, 128, 256, 1024,
   1280, 1518 bytes) and in [RFC5180] section 5 for Packet over Sonet SONET
   interfaces (47, 64, 128, 256, 1024, 1280, 1518, 2048, 4096 bytes).

   When measuring with large frame sizes care needs to be taken taken to avoid
   any packet fragmentation on the DUT interfaces which could negatively
   affect measured performance values.

4.8 Flow Export Data Packet Sizes

   The Flow monitoring performance will be affected by the packet size
   the particular implementation uses to transmit Flow Export data to
   the Collector. The used packet size SHOULD be part of the test report
   and only measurements with same packet sizes SHOULD be compared.

   The DUT export interface (see Figure 2) maximum transmission unit
   (MTU) SHOULD be configured to avoid
   any packet fragmentation on the DUT interfaces which could negatively
   affect measured performance values.

4.8 media largest available value.

4.9 Illustrative Test Set-up Examples

   The below examples represent only hypothetical test set-up to clarify
   the use of Flow monitoring parameters and configuration together with
   traffic parameters to test Flow monitoring. The actual benchmarking
   specifications are in the sections 5 and 6.

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4.8.1

4.9.1 Example 1 - Inactive Timeout Flow Expiration

   The traffic generator sends 1000 packets per second in 10000 defined
   streams, each stream identified by an unique destination IP address.
   Each stream has then packet rate 0.1 packets per second. The packets
   are sent in a round robin fashion (stream 1 to 10000) while
   incrementing the destination IP address with each sent packet.

   The configured Cache Size is 20000 Flow Records. The configured
   Active Timeout is 100 seconds, the Inactive Timeout is 5 seconds.

   Flow monitoring on the DUT uses the destination IP address as Flow
   Key.

   A packet with destination IP address equal to A is sent every 10
   seconds, so it means that the Flow Record is refreshed in the Cache
   every 10 seconds, while the Inactive Timeout is 5 seconds. In this
   case the Flow Records will expire from the Cache due to the Inactive
   Timeout and when a new packet is sent with the same IP address A it
   will create a new Flow Record in the Cache.

   The measured Flow Export Rate in this case will be 1000 Flow
   Records per second since every single sent packet will always
   create a new Flow Record and we send 1000 packets per second.

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   The expected number of Flow Record entries in the Cache during the
   whole measurement is around 5000. It corresponds to the Inactive
   Timeout being 5 seconds and during those five seconds 5000 entries
   are created. This expectation might change in real measurement
   set-ups witch large Cache Sizes and high packet rates where the
   export rate might be limited and lower than the offered Flow Export
   Rate. This behaviour is entirely implementation specific.

4.8.2

4.9.2 Example 2 - Active Timeout Flow Expiration

   The traffic generator sends 1000 packets per second in 100 defined
   streams, each stream identified by an unique destination IP address.
   Each stream has then packet rate 10 packets per second. The packets
   are sent in a round robin fashion while incrementing (stream 1 to
   100) the destination IP address with each sent packet.

   The configured Cache Size is 1000 Flow Records. The configured
   Active Timeout is 100 seconds, the Inactive Timeout is 10 seconds.

   Flow monitoring on the DUT uses as Flow Key the destination IP
   address.

   After first 100 packets sent, 100 Flow Records are created and placed
   in the Flow monitoring Cache. The subsequent packets will be counted
   against the already created Flow Records since the destination IP
   address (Flow Key) has already been seen by the DUT (provided the
   Flow Record did not expire yet as described below).

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   A packet with destination IP address equal to A is sent every 0.1
   second, so it means that the Flow Record is refreshed in the Cache
   every 0.1 second, while the Inactive Timeout is 10 seconds. In this
   case the Flow Records will not expire from the Cache until the Active
   Timeout, e.g. they will expire every 100 seconds and then the Flow
   Records will be created again.

   If the test measurement time is 50 seconds from the start of the
   traffic generator then the measured Flow Export Rate is 0 since
   during this period no Flow Records expired from the Cache.

   If the test measurement time is 100 seconds from the start of the
   traffic generator then the measured Flow Export Rate is 1 Flow Record
   per second.

   If the test measurement time is 290 seconds from the start of the
   traffic generator then the measured Flow Export Rate is 2/3 of Flow
   Record per second since during the 290 seconds period we expired 2
   times the same 100 of Flows.

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5. Flow Monitoring Throughput Measurement Methodology

   Objective:

      To measure the Flow monitoring performance in a manner comparable
      between different Flow monitoring implementations.

   Metric definition:

      Flow Monitoring Throughput - see section 3.

   Discussion:

      The Flow monitoring implementations might chose to handle
      differently Flow Export from a partially empty Cache or in the
      situation when the Cache is fully occupied by the Flow Records.
      Similarly software and hardware based DUTs can handle the same
      situation as stated above differently. The purpose of the
      benchmark measurement in this section is to abstract from all the
      possible behaviours and define one measurement procedure covering
      all the possibilities. The only criteria is to measure as defined
      here until Flow Record or packet losses are seen. The decision
      whether to dive deeper into the conditions under which the drops packet
      losses happen is left to the tester.

5.1 Flow Monitoring Configuration

   Cache Size
      Cache Size configuration is dictated by the expected position of
      the DUT in the network and by the chosen Flow Keys of the Flow
      Record. The number of unique Flow Keys sets that the traffic
      generator (sender) provides should be multiple times larger than

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      the Cache Size. This way the Flow Records in the Cache never get
      updated before Flow Expiration and Flow Export. The Cache Size
      MUST be known in order to define the measurements circumstances
      properly.

   Inactive Timeout
      Inactive Timeout is set (if configurable) to the minimum possible
      value on the network device. This makes sure the Flow Records are
      expired as soon as possible and exported out of the DUT Cache. It
      MUST be known in order to define the measurements circumstances
      properly.
      completely and equally across implementations.

   Active Timeout
      Active Timeout is set (if configurable) to equal or higher value
      than the Inactive Timeout. It MUST be known in order to define the
      measurements circumstances properly. completely and equally across
      implementations.

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   Flow Keys Definition:
      Needs to allow for large numbers of unique Flow Records to be
      created in the Cache by incrementing values of one or several Flow
      Keys. The number of unique combinations of Flow Keys values SHOULD
      be several times larger than the DUT Cache Size. This makes sure
      that any incoming packet will never refresh any already existing
      Flow Record in the Cache.

5.2 Traffic Configuration

   Traffic Generation
      The traffic generator needs to increment the Flow Keys values with
      each sent packet, this way each packet represents one Flow Record
      in the DUT Cache.

      If the used test traffic rate is below the maximum media rate for
      the particular packet size the traffic generator is expected to
      send the packets in equidistant time intervals. The traffic
      generators which do not fulfil this condition MUST NOT and cannot
      be used for the Flow Monitoring Throughput measurement. An example
      of this behaviour is if the test traffic rate is one half of the
      media rate and the traffic generator achieves this by sending each
      half of the second at the full media rate and then sending nothing
      for the second half of the second. In such conditions it would be
      impossible to distinguish if the DUT failed to handle the Flows
      due to the input buffers shortage during the burst or due to the
      limits in the Flow Monitoring performance.

   Measurement Duration
      The measurement duration MUST be at least two times longer than
      the Inactive Timeout otherwise no Flow Export would be seen. The
      measurement duration SHOULD guarantee that the number of Flow
      Records created during the measurement exceeds the available Cache
      Size on the DUT.

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5.3 Cache Population

    The product of Inactive Timeout and the packet rate offered to the
    DUT (cache population) during the measurements determines the total
    number of Flow Record entries in the DUT Cache during one particular
    measurement (while taking into account some margin for dynamic
    behaviour during high DUT loads when processing the Flows).

    The Flow monitoring implementation might behave differently
    depending on the relation of cache population to the available Cache
    Size during the measurement. This behaviour is fully implementation
    specific and will also be influenced if the DUT is software based or
    hardware based architecture.

    The cache population (if it is lower than the available Cache Size
    or higher than the available Cache Size) during a particular
    benchmark measurement SHOULD be noted and mainly only measurements
    with same cache population SHOULD be compared.

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5.4 Measurement Time Interval

   The measurement time interval is the time value which is used to
   calculate the measured Flow Expiration Rate from the captured Flow
   Export data. It is obtained as specified below.

   RFC2544 specifies with the precision of the packet beginning and end
   the time intervals to be used to measure the DUT time
   characteristics. In the case of a Flow Monitoring Throughput
   measurement the start and stop time needs to be clearly defined but
   the granularity of this definition can be limited to just marking the
   time start and stop with the start and stop of the traffic generator.
   This assumes that the traffic generator and DUT are collocated and
   the variance in transmission delay from the generator to the DUT is
   negligible as compared to the total time of traffic generation.

   The measurement start time: the time when the traffic generator is
                               started

   The measurement stop time: the time when the traffic generator is
                              stopped

   The measurement time interval is then calculated as the difference
   (stop time) - (start time) - Inactive Timeout. (Inactive Timeout).

   This supposes that the Cache Size is large enough so that the time to
   fill it up with Flow Records is longer than Inactive Timeout.
   Otherwise the time to fill up the Cache needs to be used for
   calculation of the measurement time interval in the place of the
   Inactive Timeout.

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   Instead of measuring the absolute values of stop and start time it is
   possible to setup the traffic generator to send traffic for certain
   pre-defined time interval which is then used in the above definition
   instead of the difference (stop time) - (start time).

   The Collector MUST stop collecting the Flow Export data at the
   measurement stop time.

   The Inactive Timeout (or the time needed to fill up the Cache) causes
   delay of the Flow Export data behind the test traffic which is
   forwarded by the DUT. E.g. if the traffic starts at time point X Flow
   Export will start only at the time point X + Inactive Timeout. Timeout (or X +
   time to fill up the Cache). Since Flow Export capture needs to stop
   with the traffic (because that's when the DUT stops to process the
   Flow Records at the given rate) the time interval during which the
   DUT kept exporting data is by Inactive Timeout shorter than the time
   interval when the test traffic was sent from the traffic generator to
   the DUT.

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5.5 Flow Export Rate Measurement

   The Flow Export Rate needs to be measured in two consequent steps.
   The purpose of the first step (point a. below) is to gain the actual
   value for the rate, the second step (point b. below) needs to be done
   in order to verify Flow Record drops during the measurement:

   a. In the first step the captured Flow Export data MUST be analysed analyzed
      only for the capturing interval (measurement time interval) as
      specified in section 5.4. During this period the DUT is forced to
      process Flow Records at the rate the packets are sent. When
      traffic generation finishes, the behaviour when emptying the Cache
      is completely implementation specific and the Flow Export data from
      this period cannot be therefore used for the benchmarking.
   b. In the second step all the Flow Export data from the DUT MUST be
      captured in order to be capable to determine the Flow Record losses.
      It needs to be taken into account that especially when large Cache
      Sizes (in order of magnitude of hundreds of thousands and higher)
      are in use the Flow Export can take many multiples of Inactive
      Timeout to empty the Cache after the measurement. This behaviour is
      completely implementation specific.

  If the Collector has the capability to redirect the Flow Export data
  after the measurement time interval into different capture buffer (or
  time stamp the received Flow Export data after that) this can be done
  in one step. Otherwise each Flow Monitoring Throughput measurement at
  certain packet rate needs to be executed twice - once to capture the
  Flow Export data just for the measurement time interval (to determine
  the actual Flow Expiration Rate) and second time to capture all Flow
  Export data in order to determine Flow Record losses at that packet
  rate.

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  This Flow Export Rate procedure is fully applicable to all
  measurement set-ups but can be simplified for the cases with high
  cache population (see section 5.3) when the Cache is filled up with
  Flow Records within first few seconds of the measurement. In such a
  case the DUT has no choice but to process all the Flows at the
  incoming packet rate and the Flow Export Rate is
  numerically equal to the packet rate. Thus only step b. really needs
  to be performed.

5.6 The Measurement Procedure

  The measurement procedure is same as the Throughput measurement in
  the section 26.1 of [RFC2544] for the traffic sending side. The DUT
  output analysis is done on the traffic generator receiving side for
  the test traffic the same way as for RFC2544 measurements.

  An additional analysis is performed using data captured by the
  Collector. The purpose of this analysis is to establish the value of
  Flow Export Rate during the current measurement step and to verify

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  that no Flow Records were dropped during the measurement. The
  procedure to measure Flow Export Rate is described in the section
  5.5.

  The Flow Export performance can be significantly affected by the way
  the Flow monitoring implementation formats the Flow Records into the
  Flow Export packets in terms of ordering and frequency of Control
  Information export and mainly the number of Flow Records in one Flow
  Export packet. The worst case scenario here is just one Flow Record in
  every Flow Export packet.

  Flow Export data should be sanity checked during the benchmark
  measurement for:

  a. the number of Flow Records per packet by simply calculating the
     ratio of exported Flow Records and the number of Flow Export
     packets captured during the measurement (which should be available
     as a counter on the Collector capture buffer). buffer)
  b. the number of Control Information Flow Records per Flow Export
     packet (calculated as the ratio of the total number of such Flow
     Records in the Flow Export data and the number of Flow Export
     packets). It should be several orders of magnitude less than one
     Flow Record per Flow Export packet or at most in some special
     configuration one set unique set of Control Data in each Flow Export
     packet.

6. RFC2544 Measurements

   RFC2544 measurements can be performed under two Flow Monitoring set-
   ups (see also section 3.4.2). This section details both of them and
   specifies the ways how to construct the test traffic so that RFC2544
   measurements can be performed in a controlled environment also from

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   the Flow monitoring point of view. Controlled Flow monitoring
   environment here basically means that the tester always knows what Flow monitoring
   activity (Flow Export Rate) the traffic offered to the DUT causes.

   This section is applicable mainly for the RFC2544 throughput (RFC2544
   section 26.1) and latency (RFC2544 section 26.2 )measurement. It
   could be used also to measure frame loss rate (RFC2544 section 26.3)
   and back-to-back frames (RFC2544 section 26.4). It is irrelevant for
   the rest of RFC2544 network interconnect devices characteristics.

   Objective:

      Provide RFC2544 network device characteristics in the presence of
      Flow monitoring on the DUT. The RFC2544 studies numerous
      characteristics of network devices. The DUT forwarding and time
      characteristics without Flow monitoring present on the DUT can
      significantly
      vary significantly when Flow monitoring starts to be deployed on
      the network device.

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   Metric definition:

     Metric as specified in [RFC2544].

   The measured RFC2544 Throughput MUST NOT include the packet rate
   corresponding to the Flow Export data. It data, because it is control type
   traffic, generated by the DUT as a result of enabling Flow monitoring
   and it does not contribute to the test traffic which the DUT can handle. On
   contrary it
   It requires DUT resources to be generated and transmitted and
   therefore the RFC2544 Throughput will be in most cases much lower
   in the presence of
   when Flow monitoring is enabled on the DUT. DUT than without it.

6.1 Flow Monitoring Configuration

   Flow monitoring configuration (as detailed in the section 4.3) needs
   to be applied the same way as discussed in the section 5 with the
   exception of Active Timeout configuration.

   The Active Timeout SHOULD be configured to exceed several times the
   measurement time interval (see section 5.4). This makes sure that if
   the measurements with two traffic components are performed (see
   section 6.5) there is no Flow monitoring activity related to the
   second traffic component.

   The Flow monitoring configuration does not change in any other way
   for the measurement performed in this section, what changes and makes
   the difference is the traffic configurations as specified in the
   sections below.

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6.2 Measurements With with the Flow Monitoring Throughput Set-up

   The major requirement to perform a measurement with Flow Monitoring
   Throughput set-up is that the traffic and Flow monitoring is
   configured in such a way that each sent packet creates one Flow
   Record in the DUT Cache. This restricts the possible set-ups only to
   the measurement with two traffic components as specified in the
   section 6.5.

   Note that for software based platforms (as already discussed in
   Section 3.5) the two traffic components set-up might not be
   necessary. This is to certain extent implementation specific. The two
   traffic components set-up on software based platforms can still be
   used to perform the type of measurements as discussed in the section
   B.1.

6.3 Measurements With Fixed Flow Expiration Rate

   This section covers the measurements where the RFC2544 metrics need
   to be measured with Flow monitoring enabled but at certain Flow
   Export Rate lower than Flow Monitoring Throughput.

   The tester here has both options as specified in the section 6.4 and
   6.5.

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6.4 Measurements With Single Traffic Component

   Section 12 of [RFC2544] discusses the use of protocol source and
   destination addresses for defined measurements. To perform all the
   RFC2544 type measurements with Flow monitoring enabled the defined
   Flow Keys SHOULD contain IP source and destination address. The
   RFC2544 type measurements with Flow monitoring enabled then can be
   executed under these additional conditions:

   a. the test traffic is not limited to single unique pair of source
      and destination address
   b. the traffic generator defines test traffic as follows:
      allow for a parameter to say send N (where N is an integer number
      starting at 1 and incremented in small steps) packets with source
      IP addresses address A and destination IP address B before changing both IP
      addresses to the next value

    This test traffic definition allows execution of the Flow monitoring
    measurements with fixed Flow Export Rate while measuring the DUT
    RFC2544 characteristics. This set-up is the better option since it
    best simulates the live network traffic scenario with Flows
    containing more than just one packet.

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    The initial packet rate at N equal to 1 defines the Flow Expiration
    Rate for the whole measurement procedure. The consequent increases
    of N will not change Flow Expiration Rate as the time and Cache
    characteristics of the test traffic stay the same. This set-up is
    suitable for measurements with Flow Export Rates below the Flow
    Monitoring Throughput.

6.5 Measurements With Two Traffic Components

   The test traffic set-up in the section 6.2 6.4 might be difficult to
   achieve with commercial traffic generators or the granularity of the
   traffic rates as defined by the initial packet rate at N equal to 1
   might not be suitable for the required measurement. An alternate
   mechanism is to define two traffic components in the test traffic.
   One to populate Flow monitoring Cache and the second one to execute
   the RFC2544 measurements.

   a. Flow monitoring test traffic component - the exact traffic
      definition as specified in the section 5.2.
   b. RFC2544 Test Traffic Component - test traffic as specified by
         [RFC2544]
      RFC2544 MUST create just one Flow Record in the DUT Cache. In
      the particular set-up discussed here this would mean a traffic
      stream with just one pair of unique source and destination IP
      addresses (but could be avoided if Flow Keys were for example
      UDP/TCP source and destination ports and Flow Keys did not contain
      the addresses).

   The Flow monitoring traffic component will exercise the DUT in terms
   of Flow activity while the second traffic component will measure the
   RFC2544 characteristics. The traffic rates to be reported as
   Throughput are the sum of rates of both components. The RFC2544
   metrics do not need any other change.

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   The measured RFC2544 Throughput is the sum of the packet rates of
   both traffic components, the definition of other RFC2544 metrics
   remains unchanged.

7. Flow Monitoring Accuracy

   The pure Flow monitoring measurement in section 5 provides the
   capability to verify the Flow monitoring accuracy in terms of the
   exported Flow Record data. Since every Flow Record created in the
   Cache is populated by just one packet, the full set of captured data
   on the Collector can be parsed (e.g. providing the values of all Flow
   Keys and other Flow Record fields not only the overall Flow Record
   count in the exported data) and each set of parameters from each Flow
   Record can be checked against the parameters as configured on the
   traffic generator and set in packet sent to the DUT. The exported
   Flow Record is considered accurate if:

   a. all the Flow Record fields are present in each exported Flow
      Record
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   b. all the Flow Record fields values match the value ranges as set by
      the traffic generator (for example an IP address falls within the
      range of the IP addresses increments on the traffic generator)
   c. all the possible Flow Record fields values as defined at the
      traffic generator have been found in the captured export data
      on the Collector. This check needs to be offset to potential
      detected packet losses at the DUT during the measurement

   If Packet Sampling is deployed then only verifications in point a.
   and b. above can be performed.

8. Evaluating Flow Monitoring Applicability

   The measurement results as discussed in this document and obtained
   for certain DUTs allow for a preliminary analysis of a Flow
   monitoring deployment based on the traffic analysis data from the
   providers network.

   An example of such traffic analysis in the Internet is provided by
   [CAIDA] and the way it can be used is discussed below.
   The data needed to make an estimate if a certain network device
   can manage the particular amount of live traffic with Flow monitoring
   enabled is:

   Average packet size:            350 bytes
   Number of packets per IP Flow:  20

   Expected data rate on the network device: 1 Gbit/s

   This results in:

   Expected packet rate: 357 000 pps

      being (1 Gbit/s divided by 350 bytes/packet)

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   Flows per second: 18 000

      being (packet rate 357 000 pps divided by 20 packets per IP Flow)

   It needs to be kept in mind that the above is a very rough and
   averaged Flow activity estimate which cannot account for traffic
   anomalies like large number of for example DNS request packets which
   are typically small packets coming from many different sources and
   represent mostly just one packet per Flow.

9. Acknowledgements

   This work could have been performed thanks to the patience and
   support of Cisco Systems Netflow development team, namely Paul
   Aitken, Paul Atkins and Andrew Johnson. Thanks belong to Benoit
   Claise for numerous detailed reviews and presentations of the
   document and Aamer Akhter for initiating this work.

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10. IANA Considerations

   This document requires makes no IANA considerations. requests of IANA.

11. Security Considerations

   Documents of this type do not directly affect the security of
   the Internet or corporate networks as long as benchmarking
   is not performed on devices or systems connected to operating
   networks.

   Benchmarking activities as described in this memo are limited to
   technology characterization using controlled stimuli in a laboratory
   environment, with dedicated address space and the constraints
   specified in the sections above.

   The benchmarking network topology will be an independent test setup
   and MUST NOT be connected to devices that may forward the test
   traffic into a production network, or misroute traffic to the test
   management network.

   Further, benchmarking is performed on a "black-box" basis, relying
   solely on measurements observable external to the DUT.

   Special capabilities SHOULD NOT exist in the DUT specifically for
   benchmarking purposes.  Any implications for network security arising
   from the DUT SHOULD be identical in the lab and in production
   networks.

12. References

12.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, April 1997

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   [RFC2544]  Bradner, S., "Benchmarking Methodology for Network
              Interconnect Devices", Informational, RFC 2544, April 1999

   [RFC5470]  Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
              "Architecture Model for IP Flow Information Export",
              RFC 5470, December 2010 April 2011

12.2. Informative References

   [RFC1242]  Bradner, S., "Benchmarking Terminology for Network
              Interconnection Devices", RFC 1242, July 1991

   [RFC2285]  Mandeville R., "Benchmarking Terminology for LAN Switching
              Devices", Informational, RFC 2285, November 1998

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   [RFC3031]  E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label
              Switching Architecture", Standards Track, RFC 3031,
              January 2001

   [RFC3917]  Quittek J., "Requirements for IP Flow Information Export
              (IPFIX)", Informational, RFC 3917, October 2004.

   [RFC5101]  Claise B., "Specification of the IP Flow Information
              Export (IPFIX) Protocol for the Exchange of IP Traffic
              Flow Information", Standards Track, RFC 5101, January 2008

   [RFC5102]  Quittek, J., Bryant, S., Claise, B., Aitken, P., and
              J. Meyer, "Information Model for IP Flow Information
              Export", RFC 5102, January 2008

   [RFC5180]  C. Popoviciu, A. Hamza, D. Dugatkin, G. Van de Velde,
              "IPv6 Benchmarking Methodology for Network Interconnect
              Devices", Informational, RFC 5180, May 2008

   [RFC5472]  Zseby, T., Boschi, E., Brownlee, N., Claise, B.,
              "IP Flow Information Export (IPFIX) Applicability",
              RFC 5472, December 2010

   [RFC5474]  D. Chiou, B. Claise, N. Duffield, A. Greenberg, M.
              Grossglauser, P. Marimuthu, J. Rexford, G. Sadasivan,
              "A Framework for Passive Packet Measurement" RFC 5474,
               December 2010

   [RFC5475]  T. Zseby, M. Molina, N. Duffield, F. Raspall, "Sampling
              and Filtering Techniques for IP Packet Selection"
              RFC 5475, December 2010 March 2009

   [RFC5476]  Claise, B., Quittek, J., and A. Johnson, "Packet
              Sampling (PSAMP) Protocol Specifications", RFC 5476,
               December 2010

   [RFC5477]  T. Dietz, F. Dressler, G. Carle, B. Claise,
              "Information Model for Packet Sampling Exports", RFC 5477,
               December 2010

 [PSAMP-MIB]  Dietz, T., Claise, B. "Definitions of Managed
              Objects for Packet Sampling", Internet-Draft work in
              progress, June 2006
              March 2009

   [RFC5695]  Akhter A. "MPLS Forwarding Benchmarking Methodology",
              RFC 5695, November 2009

     [CAIDA]  Claffy, K., "The nature of the beast: recent traffic
              measurements from an Internet backbone",
              http://www.caida.org/publications/papers/1998/Inet98/
              Inet98.html

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Author's Addresses

   Jan Novak (editor)
   Cisco Systems
   Edinburgh,
   United Kingdom
   Email: janovak@cisco.com

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Appendix A: Recommended Report Format
Parameter                           Units
----------------------------------- ------------------------------------
Test Case                           test case name (section 5 and 6)
Test Topology                       Figure 2, other
Traffic Type                        IPv4, IPV6, IPv6, MPLS, other

Test Results
  Flow Monitoring Throughput        Flow Records per second or Not
                                    Applicable
  Flow Export Rate                  Flow Records per second or Not
                                    Applicable
  Control Information Export Rate   Flow Records per second
  RFC2544 Throughput                packets per second
  (Other RFC2544 Metrics)           (as appropriate)

General Parameters
  Traffic Direction                 unidirectional, bidirectional
  DUT Interface Type                Ethernet, POS, ATM, other
  DUT Interface Bandwidth           MegaBits per second

Traffic Specifications
  Number of Traffic Components      (see section 6.4 and 6.5)
  For each traffic component:
  Packet Size                       bytes
  Traffic Packet Rate               packets per second
  Traffic Bit Rate                  MegaBits per second
  Number of Packets Sent            number of entries
  Incremented Packet Header Fields  list of fields
  Number of Unique Header Values    number of entries
  Number of Packets per Flow        number of entries

Flow monitoring Specifications
  Direction                         ingress, egress, both
  Observation Points                DUT interface names
  Cache Size                        number of entries
  Active Timeout                    seconds
  Inactive Timeout                  seconds
  Flow Keys                         list of fields
  Flow Record Fields                total number of fields
  Number of Flows Created           number of entries
  Flow Export Transport Protocol    UDP, TCP, SCTP, other
  Flow Export Protocol              IPFIX, Sflow, Netflow, other
  Flow Export data packet size      bytes

Packet Sampling Specifications
  Sampling Method [RFC5475]         systematic, random or none
  Sampling Interval                 milliseconds or not applicable
  Sampling Rate                     number of packets or not applicable

MPLS Specifications                 (for traffic type MPLS only)
  Tested Label Operation            imposition, swap, disposition

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Appendix B: Miscellaneous Tests

   This section lists the tests which could be useful to asses a proper
   Flow monitoring operation under various operational or stress
   conditions. These tests are not deemed suitable for any benchmarking
   for various reasons.

   B.1 DUT Under Traffic Load

      The Flow Monitoring Throughput SHOULD be measured under different
      levels of static traffic load through the DUT. This can be
      achieved only by using two traffic components as discussed in the
      section 6.5, where one traffic component exercises the Flow
      Monitoring Plane and the second traffic component loads only
      Forwarding Plane without affecting Flow monitoring (e.g. it
      creates just one and static Flow Record in the Cache).

      The variance in Flow Monitoring Throughput as function of the
      traffic load should be noted for comparison purposes between two
      DUTs of similar architecture and capability.

   B.2 In-band Flow Export

      The test topology in section 4.1 mandates the use of separate
      Flow Export interface to avoid the Flow Export data generated by
      the DUT to mix with the test traffic from the traffic generator.
      This is necessary in order to create clear and reproducible test
      conditions for the benchmark measurement.

      The real network deployment of Flow monitoring might not allow
      for such a luxury - for example on a very geographically large
      network. In such a case, Flow Export will use an ordinary traffic
      forwarding interface e.g. in-band Flow Export.

      The Flow monitoring operation should be verified with in-band
      Flow Export configuration while following these test steps:

      a. Perform benchmark test as specified in section 5
      b. One of the results will be how much bandwidth Flow Export
         used on the dedicated Flow Export interface
      c. Change Flow Export configuration to use the test interface
      d. Repeat the benchmark test while the receiver filters out the
         Flow Export data from analysis

      The expected result is that the RFC2544 Throughput achieved in
      step a. is same as the Throughput achieved in step d. provided
      that the bandwidth of the output DUT interface is not the
      bottleneck (in other words it must have enough capacity to
      forward both test and Flow Export traffic).

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   B.3 Variable Packet Size

      The Flow monitoring measurements specified in this document would
      be interesting to repeat with variable packet sizes within one
      particular test (e.g. test traffic containing mix of packet
      sizes). The packet forwarding tests specified mainly in [RFC2544]
      do not recommend and perform such tests. Flow monitoring is not
      dependent on packet sizes so such a test could be performed during
      the Flow Monitoring Throughput measurement and verify its value
      does not depend on the offered traffic packet sizes. The tests
      must be carefully designed in order to avoid measurement errors
      due to physical bandwidth limitations and changes of base
      forwarding performance with packet size.

   B.4 Bursty Traffic

      RFC2544 section 21 discusses and defines the use of bursty
      traffic. It can be used for Flow monitoring testing as well to
      gauge some short term overload DUT capabilities in terms of Flow
      monitoring. The tests benchmark here would not be the Flow
      Expiration Rate the DUT can sustain but the absolute number of
      Flow Records the DUT can process without dropping any single Flow
      Record. The traffic set-up to be used for this test is as follows:

      a. each sent packet creates a new Flow Record
      b. the packet rate is set to the maximum transmission speed of the
         DUT interface used for the test

   B.5 Various Flow Monitoring Configurations

      This section translates the terminology used in the IPFIX
      documents [RFC5470], [RFC5101] and others into the terminology
      used in this document. Section B.5.2 proposes another measurement
      which is not possible to verify in a black box test manner.

   B.5.1 RFC2544 Throughput without Metering Process

       If Metering Process is not defined on the DUT it means no Flow
       Monitoring Cache exists and no Flow analysis occurs. The
       performance measurement of the DUT in such a case is just pure
       [RFC2544] measurement.

   B.5.2 RFC2544 Throughput with Metering Process

       If only Metering Process is enabled it means that Flow analysis
       on the DUT is enabled and operational but no Flow Export happens.
       The performance measurement of a DUT in such a configuration
       represents an useful test of the DUT capabilities (this
       corresponds to the case when the network operator uses Flow
       Monitoring for example for manual denial of service attacks
       detection and does not wish to use Flow Export).

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       The performance testing on this DUT can be performed as discussed
       in this document but it is not possible to verify the operation
       and results without interrogating the DUT.

    B.5.3 RFC2544 Throughput with Metering and Exporting Process

       This test represents the performance testing as discussed in
       section 6.

   B.6 Tests With Bidirectional Traffic

   The test topology on Figure 2 can be expanded to verify Flow
   monitoring functionality with bidirectional traffic in two possible
   ways:

   a. use two sets of interfaces, one for Flow monitoring for ingress
      traffic and one for Flow monitoring egress traffic
   b. use exactly same set-up as in Figure 2 but use the interfaces in
      full duplex mode e.g. sending and receiving simultaneously on each
      of them

   The set-up in point a. above is in fact equivalent to the set-up with
   several Observation Points as already discussed in the section 4.1
   and 4.3.1.

   For the set-up in point b. same rules should be applied (as per
   section 4.1 and 4.3.1) - traffic passing through each Observation
   Point SHOULD always create a new Flow Record in the Cache e.g. the
   same traffic SHOULD NOT be just looped back on the receiving
   interfaces to create the bidirectional traffic flow.

   B.7 Instantaneous Flow Export Rate

   An additional useful information when analysing the Flow Export data
   for the Flow Expiration Rate is the time distribution of the
   instantaneous Flow Export Rate. It can be derived during the
   measurements in two ways:

   a. The Collector might provide the capability to decode Flow Export
      during capturing and at the same time counting the Flow Records
      and provide the instantaneous (or simply an average over shorter
      time interval than specified in the section 5.4) Flow Export Rate
   b. The Flow Export protocol (like IPFIX [RFC5101]) can provide time
      stamps in the Flow Export packets which would allow time based
      analysis and calculate the Flow Export Rate as an average over
      much shorter time interval than specified in the section 5.4

   The accuracy and shortest time average will always be limited by the
   precision of the time stamps (1 second for IPFIX) or by the
   capabilities of the DUT and the Collector.

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