draft-ietf-bmwg-ipflow-meth-02.txt   draft-ietf-bmwg-ipflow-meth-03.txt 
Internet Engineering Task Force Jan Novak Internet Engineering Task Force Jan Novak
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Intended status: Informational Intended status: Informational
Expires: 21 December, 2011 21 June 2011 Expires: 11 January, 2012 11 July 2011
IP Flow Information Accounting and Export Benchmarking IP Flow Information Accounting and Export Benchmarking
Methodology Methodology
draft-ietf-bmwg-ipflow-meth-02.txt draft-ietf-bmwg-ipflow-meth-03.txt
Abstract Abstract
This document provides a methodology and framework for quantifying This document provides a methodology and framework for quantifying
the performance impact of monitoring of IP flows on a network device the performance impact of monitoring of IP flows on a network device
and export of this information to a collector. It identifies the rate and export of this information to a collector. It identifies the rate
at which the IP flows are created, expired, and successfully exported at which the IP flows are created, expired, and successfully exported
as a new performance metric in combination with traditional as a new performance metric in combination with traditional
throughput. The metric is only applicable to the devices compliant throughput. The metric is only applicable to the devices compliant
with the Architecture for IP Flow Information Export [RFC5470]. with the Architecture for IP Flow Information Export [RFC5470].
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Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
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progress." progress."
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This Internet-Draft will expire on 21 December, 2011. This Internet-Draft will expire on 11 January, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
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Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described "OPTIONAL" in this document are to be interpreted as described
in RFC 2119 [RFC2119]. in RFC 2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3
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3. Flow Monitoring Performance Metric. . . . . . . . . . . . . . 6 3. Flow Monitoring Performance Metric. . . . . . . . . . . . . . 6
3.1 Definition. . . . . . . . . . . . . . . . . . . . . . . . 6 3.1 Definition. . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Device Applicability. . . . . . . . . . . . . . . . . . . 6 3.2 Device Applicability. . . . . . . . . . . . . . . . . . . 6
3.3 Measurement Concept . . . . . . . . . . . . . . . . . . . 7 3.3 Measurement Concept . . . . . . . . . . . . . . . . . . . 7
3.4 The Measurement Procedure Overview. . . . . . . . . . . . 8 3.4 The Measurement Procedure Overview. . . . . . . . . . . . 8
4. Measurement Set Up. . . . . . . . . . . . . . . . . . . . . . 9 4. Measurement Set Up. . . . . . . . . . . . . . . . . . . . . . 9
4.1 Measurement Topology. . . . . . . . . . . . . . . . . . . 9 4.1 Measurement Topology. . . . . . . . . . . . . . . . . . . 9
4.2 Base DUT Set Up. . . . . . . . . . . . . . . . . . . . . 11 4.2 Base DUT Set Up. . . . . . . . . . . . . . . . . . . . . 11
4.3 Flow Monitoring Configuration. . . . . . . . . . . . . . 11 4.3 Flow Monitoring Configuration. . . . . . . . . . . . . . 11
4.4 Collector. . . . . . . . . . . . . . . . . . . . . . . . 15 4.4 Collector. . . . . . . . . . . . . . . . . . . . . . . . 15
4.5 Packet Sampling. . . . . . . . . . . . . . . . . . . . . 16 4.5 Sampling . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6 Frame Formats. . . . . . . . . . . . . . . . . . . . . . 16 4.6 Frame Formats. . . . . . . . . . . . . . . . . . . . . . 16
4.7 Frame Sizes. . . . . . . . . . . . . . . . . . . . . . . 17 4.7 Frame Sizes. . . . . . . . . . . . . . . . . . . . . . . 16
4.8 Flow Export Data Packet Sizes. . . . . . . . . . . . . . 17 4.8 Flow Export Data Packet Sizes. . . . . . . . . . . . . . 16
4.9 Illustrative Test Set-up Examples. . . . . . . . . . . . 17 4.9 Illustrative Test Set-up Examples. . . . . . . . . . . . 17
5. Flow Monitoring Throughput Measurement Methodology . . . . . 19 5. Flow Monitoring Throughput Measurement Methodology . . . . . 18
5.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 19 5.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 18
5.2 Traffic Configuration. . . . . . . . . . . . . . . . . . 20 5.2 Traffic Configuration. . . . . . . . . . . . . . . . . . 19
5.3 Cache Population . . . . . . . . . . . . . . . . . . . . 20 5.3 Cache Population . . . . . . . . . . . . . . . . . . . . 19
5.4 Measurement Time Interval. . . . . . . . . . . . . . . . 20 5.4 Measurement Time Interval. . . . . . . . . . . . . . . . 20
5.5 Flow Export Rate Measurement . . . . . . . . . . . . . . 21 5.5 Flow Export Rate Measurement . . . . . . . . . . . . . . 21
5.6 The Measurement Procedure. . . . . . . . . . . . . . . . 22 5.6 The Measurement Procedure. . . . . . . . . . . . . . . . 21
6. RFC2544 Measurements . . . . . . . . . . . . . . . . . . . . 23 6. RFC2544 Measurements . . . . . . . . . . . . . . . . . . . . 22
6.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 23 6.1 Flow Monitoring Configuration. . . . . . . . . . . . . . 23
6.2 Measurements With the Flow Monitoring Throughput Set-up. 24 6.2 Measurements With the Flow Monitoring Throughput Set-up. 23
6.3 Measurements With Fixed Flow Export Rate . . . . . . . . 24 6.3 Measurements With Fixed Flow Export Rate . . . . . . . . 23
6.4 Measurements With Single Traffic Component . . . . . . . 24 6.4 Measurements With Single Traffic Component . . . . . . . 23
6.5 Measurements With Two Traffic Components . . . . . . . . 25 6.5 Measurements With Two Traffic Components . . . . . . . . 24
7. Flow Monitoring Accuracy . . . . . . . . . . . . . . . . . . 25 7. Flow Monitoring Accuracy . . . . . . . . . . . . . . . . . . 25
8. Evaluating Flow Monitoring Applicability . . . . . . . . . . 26 8. Evaluating Flow Monitoring Applicability . . . . . . . . . . 25
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
10. Security Considerations . . . . . . . . . . . . . . . . . . 27 10. Security Considerations . . . . . . . . . . . . . . . . . . 26
11. References. . . . . . . . . . . . . . . . . . . . . . . . . 27 11. References. . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1 Normative References. . . . . . . . . . . . . . . . . . 27 11.1 Normative References. . . . . . . . . . . . . . . . . . 26
11.2 Informative References. . . . . . . . . . . . . . . . . 27 11.2 Informative References. . . . . . . . . . . . . . . . . 27
Appendix A: Recommended Report Format . . . . . . . . . . . . . 29 Appendix A: Recommended Report Format . . . . . . . . . . . . . 28
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Appendix B: Miscellaneous Tests . . . . . . . . . . . . . . . . 30 Appendix B: Miscellaneous Tests . . . . . . . . . . . . . . . . 29
B.1 DUT Under Traffic Load . . . . . . . . . . . . . . . . . 30 B.1 DUT Under Traffic Load . . . . . . . . . . . . . . . . . 29
B.2 In-band Flow Export. . . . . . . . . . . . . . . . . . . 30 B.2 In-band Flow Export. . . . . . . . . . . . . . . . . . . 29
B.3 Variable Packet Rate . . . . . . . . . . . . . . . . . . 30 B.3 Variable Packet Rate . . . . . . . . . . . . . . . . . . 30
B.4 Bursty Traffic . . . . . . . . . . . . . . . . . . . . . 31 B.4 Bursty Traffic . . . . . . . . . . . . . . . . . . . . . 30
B.5 Various Flow Monitoring Configurations . . . . . . . . . 31 B.5 Various Flow Monitoring Configurations . . . . . . . . . 30
B.6 Tests With Bidirectional Traffic . . . . . . . . . . . . 32 B.6 Tests With Bidirectional Traffic . . . . . . . . . . . . 31
B.7 Instantaneous Flow Export Rate . . . . . . . . . . . . . 32 B.7 Instantaneous Flow Export Rate . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
Monitoring of IP flows (Flow monitoring) is defined in the Monitoring of IP flows (Flow monitoring) is defined in the
Architecture for IP Flow Information Export [RFC5470] and related Architecture for IP Flow Information Export [RFC5470] and related
IPFIX documents. It analyses the traffic using predefined fields IPFIX documents. It analyses the traffic using predefined fields
from the packet header as keys and stores the traffic and from the packet header as keys and stores the traffic and
other internal information in the DUT (Device Under Test) memory. other internal information in the DUT (Device Under Test) memory.
This cached flow information is then formatted into records (see This cached flow information is then formatted into records (see
section 2.1 for term definitions) and exported from the DUT to an section 2.1 for term definitions) and exported from the DUT to an
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The most significant performance parameter is the rate at which IP The most significant performance parameter is the rate at which IP
flows are created and expired in the network device's memory and flows are created and expired in the network device's memory and
exported to a collector. Therefore, this document focuses on a exported to a collector. Therefore, this document focuses on a
methodology for how to measure the maximum IP flow rate that a methodology for how to measure the maximum IP flow rate that a
network device can sustain without impacting the forwarding plane, network device can sustain without impacting the forwarding plane,
without losing any IP flow information, and without compromising the without losing any IP flow information, and without compromising the
IP flow accuracy (see section 7 for details). IP flow accuracy (see section 7 for details).
[RFC2544], [RFC5180] and [RFC5695] specify benchmarking of network [RFC2544], [RFC5180] and [RFC5695] specify benchmarking of network
devices forwarding IPv4, IPv6 and MPLS [RFC3031] traffic, devices forwarding IPv4, IPv6 and MPLS [RFC3031] traffic,
respectively. The methodology specified in this document stays the respectively. The methodology specified in this document stays the
same for any traffic type. The only restriction may be the DUT lack same for any traffic type. The only restriction may be the DUT lack
of support for Flow monitoring support of the particular traffic of support for Flow monitoring support of the particular traffic
type. type.
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A variety of different network device architectures exist that are A variety of different network device architectures exist that are
capable of Flow monitoring and export. As such, this document does capable of Flow monitoring and export. As such, this document does
not attempt to list the various white box variables (CPU load, not attempt to list the various white box variables (CPU load,
memory utilization, TCAM utilization etc) that could be gathered as memory utilization, TCAM utilization etc) that could be gathered as
they always help in comparison evaluations. A more complete they always help in comparison evaluations. A more complete
understanding of the stress points of a particular device can be understanding of the stress points of a particular device can be
attained using this internal information and the tester MAY choose attained using this internal information and the tester MAY choose
to gather this information during the measurement iterations. to gather this information during the measurement iterations.
2. Terminology 2. Terminology
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Control Information [RFC5470, section 2] Control Information [RFC5470, section 2]
Data Stream [RFC5470, section 2] Data Stream [RFC5470, section 2]
Flow Expiration [RFC5470, section 5.1.1] Flow Expiration [RFC5470, section 5.1.1]
Flow Export [RFC5470, section 5.1.2] Flow Export [RFC5470, section 5.1.2]
Throughput [RFC1242, section 3.17] Throughput [RFC1242, section 3.17]
Packet Sampling [RFC5476, section 2]
2.2 New Terminology 2.2 New Terminology
2.2.1 Cache 2.2.1 Cache
Definition: Definition:
Memory area held and dedicated by the DUT to store Flow Memory area held and dedicated by the DUT to store Flow
information prior to the Flow Expiration. information prior to the Flow Expiration.
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2.2.2 Cache Size 2.2.2 Cache Size
Definition: Definition:
The size of the Cache in terms of how many entries the Cache can The size of the Cache in terms of how many entries the Cache can
hold. hold.
Discussion: Discussion:
This term is typically represented as a configurable option in This term is typically represented as a configurable option in
the particular Flow monitoring implementation. Its highest value the particular Flow monitoring implementation. Its highest value
will depend on the memory available in the network device. will depend on the memory available in the network device.
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Cache entry have been observed during the interval. Cache entry have been observed during the interval.
Discussion: Discussion:
This term is typically represented as a configurable option in the This term is typically represented as a configurable option in the
particular Flow monitoring implementation. See section 5.1.1 of particular Flow monitoring implementation. See section 5.1.1 of
[RFC5470] for more detailed discussion. [RFC5470] for more detailed discussion.
Measurement units: Measurement units:
Seconds Seconds
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2.2.5 Flow Export Rate 2.2.5 Flow Export Rate
Definition: Definition:
The number of Cache entries that expire from the Cache (as defined The number of Cache entries that expire from the Cache (as defined
by the Flow Expiration term) and are exported to the Collector by the Flow Expiration term) and are exported to the Collector
within a measurement time interval. within a measurement time interval.
The measured Flow Export Rate MUST include BOTH the Data Stream The measured Flow Export Rate MUST include BOTH the Data Stream
and the Control Information, as defined in section 2 of [RFC5470]. and the Control Information, as defined in section 2 of [RFC5470].
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to process Flow Export data. The physical layer issues, like to process Flow Export data. The physical layer issues, like
insufficient bandwidth from the DUT to the Collector or lack of insufficient bandwidth from the DUT to the Collector or lack of
Collector resources MUST be excluded as detailed in the section 4. Collector resources MUST be excluded as detailed in the section 4.
3.2 Device Applicability 3.2 Device Applicability
The Flow monitoring performance metric is applicable to network The Flow monitoring performance metric is applicable to network
devices that implement [RFC5470] architecture. These devices can be devices that implement [RFC5470] architecture. These devices can be
network packet forwarding devices or appliances which analyze network packet forwarding devices or appliances which analyze
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the traffic but do not forward traffic (probes, sniffers, the traffic but do not forward traffic (probes, sniffers,
replicators). replicators).
This document does not intend to measure Collector performance, it This document does not intend to measure Collector performance, it
only requires sufficient Collector resources (as specified in the only requires sufficient Collector resources (as specified in the
section 4.4) in order to measure the DUT characteristics. section 4.4) in order to measure the DUT characteristics.
3.3 Measurement Concept 3.3 Measurement Concept
Figure 1 below presents the functional block diagram of the DUT. The Figure 1 below presents the functional block diagram of the DUT. The
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Figure 1. The functional block diagram of the DUT Figure 1. The functional block diagram of the DUT
The Flow monitoring enabled (see section 4.3) on the DUT and The Flow monitoring enabled (see section 4.3) on the DUT and
represented in the figure 1 by the Monitoring Plane uses the represented in the figure 1 by the Monitoring Plane uses the
traffic information provided by the Forwarding Plane and configured traffic information provided by the Forwarding Plane and configured
Flow Keys to create Cache entries representing the traffic Flow Keys to create Cache entries representing the traffic
forwarded (or observed) by the DUT in the DUT Cache. The Cache forwarded (or observed) by the DUT in the DUT Cache. The Cache
entries are expired from the Cache depending on the Cache entries are expired from the Cache depending on the Cache
configuration (ie, the Active and Inactive Timeouts, number of Cache configuration (ie, the Active and Inactive Timeouts, number of Cache
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entries and the Cache Size) and the traffic pattern. The Cache entries and the Cache Size) and the traffic pattern. The Cache
entries are used by the Exporting Process to format the Flow Records entries are used by the Exporting Process to format the Flow Records
which are then exported from the DUT to the Collector (see figure 2 which are then exported from the DUT to the Collector (see figure 2
in section 4). in section 4).
The Forwarding Plane and Monitoring Plane represent two separate The Forwarding Plane and Monitoring Plane represent two separate
functional blocks, each with it's own performance capability. The functional blocks, each with it's own performance capability. The
Forwarding Plane handles user data packets and is fully characterised Forwarding Plane handles user data packets and is fully characterised
by the metrics defined by [RFC2544]. by the metrics defined by [RFC2544].
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type represents the most demanding traffic from the Flow monitoring type represents the most demanding traffic from the Flow monitoring
point of view and will exercise the Monitoring Plane (see figure 1) point of view and will exercise the Monitoring Plane (see figure 1)
of the DUT most. In this scenario every packet seen by DUT creates a of the DUT most. In this scenario every packet seen by DUT creates a
new Cache entry and forces the DUT to the full Cache processing new Cache entry and forces the DUT to the full Cache processing
instead of just updating packet and byte counters on an already instead of just updating packet and byte counters on an already
existing Cache entry. existing Cache entry.
The exit criteria for the Flow Monitoring Throughput measurement are The exit criteria for the Flow Monitoring Throughput measurement are
one of the following (e.g. if any of the conditions is reached): one of the following (e.g. if any of the conditions is reached):
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a. The Flow Export Rate at which the DUT starts to lose Flow a. The Flow Export Rate at which the DUT starts to lose Flow
information or the Flow information gets corrupted information or the Flow information gets corrupted
b. The Flow Export Rate at which the Forwarding Plane starts to drop b. The Flow Export Rate at which the Forwarding Plane starts to drop
or corrupt packets (if the Forwarding Plane is present) or corrupt packets (if the Forwarding Plane is present)
A corrupted packet here means the packet header corruption (resulting A corrupted packet here means the packet header corruption (resulting
in the cyclic redundancy check failure on the transmission level and in the cyclic redundancy check failure on the transmission level and
consequent packet drop) or the packet payload corruption leading to consequent packet drop) or the packet payload corruption leading to
the lost application level data. the lost application level data.
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The Forwarding Plane (see figure 1) performance metrics are fully The Forwarding Plane (see figure 1) performance metrics are fully
specified by [RFC2544] and MUST be measured accordingly. A detailed specified by [RFC2544] and MUST be measured accordingly. A detailed
traffic analysis (see below) with relation to Flow monitoring MUST be traffic analysis (see below) with relation to Flow monitoring MUST be
performed prior of any [RFC2544] measurements. Mainly the Flow Export performed prior of any [RFC2544] measurements. Mainly the Flow Export
Rate caused by the test traffic during an [RFC2544] measurement MUST Rate caused by the test traffic during an [RFC2544] measurement MUST
be known and reported. be known and reported.
The required test traffic analysis mainly involves the following: The required test traffic analysis mainly involves the following:
a. Which packet header parameters are incremented or changed during a. Which packet header parameters are incremented or changed during
traffic generation traffic generation
b. Which Flow Keys the Flow monitoring configuration uses to generate b. Which Flow Keys the Flow monitoring configuration uses to generate
Flow Records Flow Records
The RFC2544 performance metrics can be measured in one of the three The RFC2544 performance metrics can be measured in one of the three
modes: modes:
a. As a baseline of forwarding performance without Flow monitoring a. As a baseline of forwarding performance without Flow monitoring
b. At a certain level of Flow monitoring activity specified by a Flow b. At a certain level of Flow monitoring activity specified by a Flow
Export Rate lower than the Flow Monitoring Throughput Export Rate lower than the Flow Monitoring Throughput
c. At the maximum level of Flow monitoring performance, e.g. using c. At the maximum level of Flow monitoring performance, e.g. using
traffic conditions representing a measurement of Flow Monitoring traffic conditions representing a measurement of Flow Monitoring
Throughput Throughput
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to perform Flow monitoring performance measurement. The recommended to perform Flow monitoring performance measurement. The recommended
reporting format can be found in Appendix A. reporting format can be found in Appendix A.
4.1 Measurement Topology 4.1 Measurement Topology
The measurement topology described in this section is applicable only The measurement topology described in this section is applicable only
to the measurements with packet forwarding network devices. The to the measurements with packet forwarding network devices. The
possible architectures and implementation of the traffic monitoring possible architectures and implementation of the traffic monitoring
appliances (see section 3.2) are too various to be covered in this appliances (see section 3.2) are too various to be covered in this
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document. Instead of the Forwarding Plane, these appliances generally document. Instead of the Forwarding Plane, these appliances generally
have some kind of feed (an optical splitter, an interface sniffing have some kind of feed (an optical splitter, an interface sniffing
traffic on a shared media or an internal channel on the DUT providing traffic on a shared media or an internal channel on the DUT providing
a copy of the traffic) providing the information about the traffic a copy of the traffic) providing the information about the traffic
necessary for Flow monitoring analysis. The measurement topology then necessary for Flow monitoring analysis. The measurement topology then
needs to be adjusted to the appliance architecture. needs to be adjusted to the appliance architecture.
The measurement set-up is identical to that used by [RFC2544], with The measurement set-up is identical to that used by [RFC2544], with
the addition of a Collector to analyze the Flow Export(see figure 2). the addition of a Collector to analyze the Flow Export(see figure 2).
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used for forwarding the test traffic but only for the Flow Export used for forwarding the test traffic but only for the Flow Export
data containing the Flow Records. In all measurements, the export data containing the Flow Records. In all measurements, the export
interface MUST have enough bandwidth to transmit Flow Export data interface MUST have enough bandwidth to transmit Flow Export data
without congestion. In other words, the export interface MUST NOT be without congestion. In other words, the export interface MUST NOT be
a bottleneck during the measurement. a bottleneck during the measurement.
Note that more complex topologies might be required. For example, if Note that more complex topologies might be required. For example, if
the effects of enabling Flow monitoring on several interfaces are of the effects of enabling Flow monitoring on several interfaces are of
concern or the media maximum speed is less than the DUT throughput, concern or the media maximum speed is less than the DUT throughput,
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the topology can be expanded with several input and output ports. the topology can be expanded with several input and output ports.
However, the topology MUST be clearly written in the measurement However, the topology MUST be clearly written in the measurement
report. report.
4.2 Baseline DUT Set Up 4.2 Baseline DUT Set Up
The baseline DUT set-up and the way the set-up is reported in the The baseline DUT set-up and the way the set-up is reported in the
measurement results is fully specified in Section 7 of [RFC2544]. measurement results is fully specified in Section 7 of [RFC2544].
The baseline DUT configuration might include other features like The baseline DUT configuration might include other features like
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the Flow monitoring traffic analysis is to be performed. the Flow monitoring traffic analysis is to be performed.
The (*) in Figure 2 designates the Observation Points in the The (*) in Figure 2 designates the Observation Points in the
default configuration. Other DUT Observation Points might be default configuration. Other DUT Observation Points might be
configured depending on the specific measurement needs as follows: configured depending on the specific measurement needs as follows:
a. ingress port/ports(s) only a. ingress port/ports(s) only
b. egress port(s) /ports only b. egress port(s) /ports only
c. both ingress and egress c. both ingress and egress
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Generally, the placement of Observation Points depends upon the Generally, the placement of Observation Points depends upon the
position of the DUT in the deployed network and the purpose of position of the DUT in the deployed network and the purpose of
Flow monitoring. See [RFC3917] for detailed discussion. The Flow monitoring. See [RFC3917] for detailed discussion. The
measurement procedures are otherwise the same for all these measurement procedures are otherwise the same for all these
possible configurations. possible configurations.
In the case when both ingress and egress Flow monitoring is In the case when both ingress and egress Flow monitoring is
enabled on one DUT the results analysis needs to take into account 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 that each Flow will be represented in the DUT Cache by two Flow
Records (one for each direction) and therefore also the Flow Records (one for each direction) and therefore also the Flow
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account when designing the measurement as specified in section 5. account when designing the measurement as specified in section 5.
The Cache's Inactive and Active Timeouts MUST be known and taken The Cache's Inactive and Active Timeouts MUST be known and taken
into account when designing the measurement as specified in into account when designing the measurement as specified in
section 5. If the Flow monitoring implementation allows only section 5. If the Flow monitoring implementation allows only
timeouts zero (e.g. immediate timeout or non-existent Cache) then timeouts zero (e.g. immediate timeout or non-existent Cache) then
the measurement conditions in the section 5 are fulfilled the measurement conditions in the section 5 are fulfilled
inherently without any additional configuration. The DUT simply inherently without any additional configuration. The DUT simply
exports instantly information about every single packet. exports instantly information about every single packet.
The Cache Size, the Inactive and Active Timeouts, and if present, The Cache Size, the Inactive and Active Timeouts MUST be included
the specific Packet Sampling techniques and associated parameters as part of the results report.
MUST be included as part of the results report.
4.3.3 Exporting Process 4.3.3 Exporting Process
The Exporting Process MUST be configured in order to export the The Exporting Process MUST be configured in order to export the
Flow Record data to the Collector. Flow Record data to the Collector.
The Exporting Process MUST be configured in such a way that all The Exporting Process MUST be configured in such a way that all
Flow Records from all configured Observation Points are exported Flow Records from all configured Observation Points are exported
towards the Collector, after the expiration policy composed of towards the Collector, after the expiration policy composed of
the Inactive and Active Timeouts and Cache Size. the Inactive and Active Timeouts and Cache Size.
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The Exporting Process SHOULD be configured with IPFIX [RFC5101] as The Exporting Process SHOULD be configured with IPFIX [RFC5101] as
the protocol to use to format the Flow Export data. If the Flow the protocol to use to format the Flow Export data. If the Flow
monitoring implementation does not support it, proprietary monitoring implementation does not support it, proprietary
protocols MAY be used. protocols MAY be used.
Various Flow monitoring implementations might use different Various Flow monitoring implementations might use different
default values regarding the export of Control Information default values regarding the export of Control Information
[RFC5470]. The Flow Export corresponding to Control Information [RFC5470]. The Flow Export corresponding to Control Information
SHOULD be analyzed and reported as a separate item on the SHOULD be analyzed and reported as a separate item on the
measurement report. Preferably, the export of Control Information measurement report. Preferably, the export of Control Information
SHOULD always be configured consistently across all testing. SHOULD always be configured consistently across all testing and
configured to the minimal possible value - ideally just one
exported set of Control Information during each measurement.
Section 10 [RFC5101] and section 8.1 of [RFC5470] discuss the Section 10 [RFC5101] and section 8.1 of [RFC5470] discuss the
possibility of deploying various transport layer protocols to possibility of deploying various transport layer protocols to
deliver Flow Export data from the DUT to the Collector. The deliver Flow Export data from the DUT to the Collector. The
selected protocol MUST be included in the measurement report. Only selected protocol MUST be included in the measurement report. Only
benchmarks with the same transport layer protocol should be benchmarks with the same transport layer protocol should be
compared. If the Flow monitoring implementation allows the use of compared. If the Flow monitoring implementation allows the use of
multiple the transport layer protocols, each of the protocols multiple the transport layer protocols, each of the protocols
SHOULD be measured in a separate measurement run and the results SHOULD be measured in a separate measurement run and the results
reported independently in the report. reported independently in the report.
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implementation might allow the user to define their own arbitrary implementation might allow the user to define their own arbitrary
Flow Record to monitor the traffic. The requirement for the Flow Record to monitor the traffic. The requirement for the
measurements defined in this document is only the need for a large measurements defined in this document is only the need for a large
number of Cache entries in the Cache. The Flow Keys needed to number of Cache entries in the Cache. The Flow Keys needed to
achieve that will typically be source and destination IP addresses achieve that will typically be source and destination IP addresses
and transport level port numbers. and transport level port numbers.
The recommended full IPv4, IPv6 or MPLS Flow Record is shown The recommended full IPv4, IPv6 or MPLS Flow Record is shown
below: below:
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Flow Keys: Flow Keys:
Source IP address Source IP address
Destination IP address Destination IP address
MPLS label (for MPLS traffic type only) MPLS label (for MPLS traffic type only)
Transport layer source port Transport layer source port
Transport layer destination port Transport layer destination port
IP protocol number (IPv6 next header) IP protocol number (IPv6 next header)
IP type of service (IPv6 traffic class) IP type of service (IPv6 traffic class)
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Table 2: User-defined Configuration Table 2: User-defined Configuration
The Flow Record configuration MUST be clearly noted in the The Flow Record configuration MUST be clearly noted in the
measurement report. The Flow Monitoring Throughput measurements on measurement report. The Flow Monitoring Throughput measurements on
different DUTs or different Flow monitoring implementations MUST different DUTs or different Flow monitoring implementations MUST
be compared only for exactly the same Flow Record configuration. be compared only for exactly the same Flow Record configuration.
4.3.5 Flow Monitoring With Multiple Configurations 4.3.5 Flow Monitoring With Multiple Configurations
The Flow monitoring architecture as specified in [RFC5470] allows The Flow monitoring architecture as specified in [RFC5470] allows
for more complicated configurations with multiple Metering and for more complicated configurations with multiple Metering and
Exporting Processes on a single DUT. Depending on the particular Exporting Processes on a single DUT. Depending on the particular
Flow monitoring implementation it might affect the measured DUT Flow monitoring implementation it might affect the measured DUT
performance. The test report should therefore contain information performance. The test report should therefore contain information
containing on how many Metering and Exporting processes were containing on how many Metering and Exporting processes were
configured on the DUT for the selected Observation Points. configured on the DUT for the selected Observation Points.
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The examples of such possible configurations are: The examples of such possible configurations are:
a. Several Observation Points with a single Metering Process and a a. Several Observation Points with a single Metering Process and a
single Exporting Process single Exporting Process
b. Several Observation Points, each with one Metering Process but b. Several Observation Points, each with one Metering Process but
all using just one instance of Exporting Process all using just one instance of Exporting Process
c. Several Observation Points with per Observation Point Metering c. Several Observation Points with per Observation Point Metering
Process and Exporting Process Process and Exporting Process
4.3.6 MPLS Measurement Specifics 4.3.6 MPLS Measurement Specifics
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4.3.3) to transmit Flow Export data, the Collector MUST have 4.3.3) to transmit Flow Export data, the Collector MUST have
sufficient resources to guarantee non-blocking data transmission on sufficient resources to guarantee non-blocking data transmission on
the transport layer session. the transport layer session.
During the analysis, the Flow Export data needs to be decoded and the During the analysis, the Flow Export data needs to be decoded and the
received Flow Records counted. received Flow Records counted.
The capture buffer MUST be cleared at the beginning of each The capture buffer MUST be cleared at the beginning of each
measurement. measurement.
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4.5 Packet Sampling 4.5 Sampling
A Flow monitoring implementation might provide the capability to
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
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 traffic receiver (Figure 2),
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 and the measured Flow Export Rate
stays unaffected by sampling.
If Flow accuracy analysis (see section 7) is performed, the results
will always be 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 Packet sampling and flow sampling is out of scope of this document.
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 measurement 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 4.6 Frame Formats
Flow monitoring itself is not dependent in any way on the media used 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 on the input and output ports. Any media can be used as supported by
the DUT and the test equipment. the DUT and the test equipment.
At the time of writing the most common transmission media and At the time of writing the most common transmission media and
corresponding frame formats (Ethernet, Packet over SONET) for IPv4, corresponding frame formats (Ethernet, Packet over SONET) for IPv4,
IPv6 and MPLS traffic are specified within [RFC2544], [RFC5180] and IPv6 and MPLS traffic are specified within [RFC2544], [RFC5180] and
[RFC5695]. [RFC5695].
The presented frame formats MUST be recorded in the report. The presented frame formats MUST be recorded in the report.
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4.7 Frame Sizes 4.7 Frame Sizes
Frame sizes of the traffic to be analyzed by the DUT are specified in Frame sizes of the traffic to be analyzed by the DUT are specified in
[RFC2544] section 9 for Ethernet type interfaces (64, 128, 256, 1024, [RFC2544] section 9 for Ethernet type interfaces (64, 128, 256, 1024,
1280, 1518 bytes) and in [RFC5180] section 5 for Packet over SONET 1280, 1518 bytes) and in [RFC5180] section 5 for Packet over SONET
interfaces (47, 64, 128, 256, 1024, 1280, 1518, 2048, 4096 bytes). interfaces (47, 64, 128, 256, 1024, 1280, 1518, 2048, 4096 bytes).
When measuring with large frame sizes, care needs to be taken to When measuring with large frame sizes, care needs to be taken to
avoid any packet fragmentation on the DUT interfaces which could avoid any packet fragmentation on the DUT interfaces which could
negatively affect measured performance values. negatively affect measured performance values.
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The below examples represent a hypothetical test set-up to clarify The below examples represent a hypothetical test set-up to clarify
the use of Flow monitoring parameters and configuration, together the use of Flow monitoring parameters and configuration, together
with traffic parameters to test Flow monitoring. The actual with traffic parameters to test Flow monitoring. The actual
benchmarking specifications are in sections 5 and 6. benchmarking specifications are in sections 5 and 6.
4.9.1 Example 1 - Inactive Timeout Flow Expiration 4.9.1 Example 1 - Inactive Timeout Flow Expiration
The traffic generator sends 1000 packets per second in 10000 defined The traffic generator sends 1000 packets per second in 10000 defined
streams, each stream identified by an unique destination IP address. streams, each stream identified by an unique destination IP address.
Therefore each stream has a packet rate of 0.1 packets per second. Therefore each stream has a packet rate of 0.1 packets per second.
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The packets are sent in a round robin fashion (stream 1 to 10000) The packets are sent in a round robin fashion (stream 1 to 10000)
while incrementing the destination IP address for each sent packet. while incrementing the destination IP address for each sent packet.
The configured Cache Size is 20000 Flow Records. The configured The configured Cache Size is 20000 Flow Records. The configured
Active Timeout is 100 seconds, the Inactive Timeout is 5 seconds. Active Timeout is 100 seconds, the Inactive Timeout is 5 seconds.
Flow monitoring on the DUT uses the destination IP address as the Flow monitoring on the DUT uses the destination IP address as the
Flow Key. Flow Key.
A packet with destination IP address equal to A is sent every 10 A packet with destination IP address equal to A is sent every 10
seconds, so the Cache entry would be refreshed in the Cache every 10 seconds, so the Cache entry would be refreshed in the Cache every 10
seconds. However, the Inactive Timeout is 5 seconds, so the Cache seconds. However, the Inactive Timeout is 5 seconds, so the Cache
entries will expire from the Cache due to the Inactive Timeout and entries 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 when a new packet is sent with the same IP address A it will create a
new entry in the Cache. new entry in the Cache.
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The measured Flow Export Rate in this case will be 1000 Flow The measured Flow Export Rate in this case will be 1000 Flow
Records per second since every single sent packet will always Records per second since every single sent packet will always
create a new Cache entry and we send 1000 packets per second. create a new Cache entry and we send 1000 packets per second.
The expected number of Cache entries in the Cache during the whole The expected number of Cache entries in the Cache during the whole
measurement is around 5000. It corresponds to the Inactive Timeout measurement is around 5000. It corresponds to the Inactive Timeout
being 5 seconds and during those five seconds 5000 entries are being 5 seconds and during those five seconds 5000 entries are
created. This expectation might change in real measurement set-ups created. This expectation might change in real measurement set-ups
with large Cache Sizes and high packet rate where the DUT actual with large Cache Sizes and high packet rate where the DUT actual
export rate might be limited and lower than the Flow Expiration export rate might be limited and lower than the Flow Expiration
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After the first 100 packets are sent, 100 Cache entries will have After the first 100 packets are sent, 100 Cache entries will have
been created in the Flow monitoring Cache. The subsequent packets been created in the Flow monitoring Cache. The subsequent packets
will be counted against the already created Cache entries since the will be counted against the already created Cache entries since the
destination IP address (Flow Key) has already been seen by the DUT destination IP address (Flow Key) has already been seen by the DUT
(provided the Cache entries did not expire yet as described below). (provided the Cache entries did not expire yet as described below).
A packet with destination IP address equal to A is sent every 0.1 A packet with destination IP address equal to A is sent every 0.1
second, so it means that the Cache entry is refreshed in the Cache second, so it means that the Cache entry is refreshed in the Cache
every 0.1 second, while the Inactive Timeout is 10 seconds. In this every 0.1 second, while the Inactive Timeout is 10 seconds. In this
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case the Cache entries will not expire until the Active Timeout, e.g. case the Cache entries will not expire until the Active Timeout, e.g.
they will expire every 100 seconds and then the Cache entries will be they will expire every 100 seconds and then the Cache entries will be
created again. created again.
If the test measurement time is 50 seconds from the start of the If the test measurement time is 50 seconds from the start of the
traffic generator then the measured Flow Export Rate is 0 since traffic generator then the measured Flow Export Rate is 0 since
during this period nothing expired from the Cache. during this period nothing expired from the Cache.
If the test measurement time is 100 seconds from the start of the 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 traffic generator then the measured Flow Export Rate is 1 Flow Record
per second. per second.
If the test measurement time is 290 seconds from the start of the 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 traffic generator then the measured Flow Export Rate is 2/3 of Flow
Record per second since during the 290 seconds period we expired the Record per second since during the 290 seconds period we expired the
same 100 of Flows twice. same 100 of Flows twice.
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5. Flow Monitoring Throughput Measurement Methodology 5. Flow Monitoring Throughput Measurement Methodology
Objective: Objective:
To measure the Flow monitoring performance in a manner comparable To measure the Flow monitoring performance in a manner comparable
between different Flow monitoring implementations. between different Flow monitoring implementations.
Metric definition: Metric definition:
Flow Monitoring Throughput - see section 3. Flow Monitoring Throughput - see section 3.
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Cache Size Cache Size
Cache Size configuration is dictated by the expected position of Cache Size configuration is dictated by the expected position of
the DUT in the network and by the chosen Flow Keys of the Flow 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 Record. The number of unique Flow Keys sets that the traffic
generator (sender) provides should be multiple times larger than generator (sender) provides should be multiple times larger than
the Cache Size, to ensure that the existing Cache entries are the Cache Size, to ensure that the existing Cache entries are
never updated before Flow Expiration and Flow Export. The Cache never updated before Flow Expiration and Flow Export. The Cache
Size MUST be known in order to define the measurement Size MUST be known in order to define the measurement
circumstances properly. circumstances properly.
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Inactive Timeout Inactive Timeout
Inactive Timeout is set (if configurable) to the minimum possible Inactive Timeout is set (if configurable) to the minimum possible
value on the DUT. This ensures that the Cache entries are expired value on the DUT. This ensures that the Cache entries are expired
as soon as possible and exported out of the DUT Cache. It MUST be as soon as possible and exported out of the DUT Cache. It MUST be
known in order to define the measurement circumstances completely known in order to define the measurement circumstances completely
and equally across implementations. and equally across implementations.
Active Timeout Active Timeout
Active Timeout is set (if configurable) to a value equal to or Active Timeout is set (if configurable) to a value equal to or
higher than the Inactive Timeout. It MUST be known in order to higher than the Inactive Timeout. It MUST be known in order to
define the measurement circumstances completely and equally define the measurement circumstances completely and equally
across implementations. across implementations.
Flow Keys Definition: Flow Keys Definition:
The test needs large numbers of unique Cache entries to be created The test needs large numbers of unique Cache entries to be created
by incrementing values of one or several Flow Keys. The number of by incrementing values of one or several Flow Keys. The number of
unique combinations of Flow Keys values SHOULD be several times unique combinations of Flow Keys values SHOULD be several times
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larger than the DUT Cache Size. This makes sure that any incoming larger than the DUT Cache Size. This makes sure that any incoming
packet will never refresh any already existing Cache entry. packet will never refresh any already existing Cache entry.
5.2 Traffic Configuration 5.2 Traffic Configuration
Traffic Generation Traffic Generation
The traffic generator needs to increment the Flow Keys values with The traffic generator needs to increment the Flow Keys values with
each sent packet, this way each packet represents one Cache entry each sent packet, this way each packet represents one Cache entry
in the DUT Cache. in the DUT Cache.
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Timeout otherwise no Flow Export would be seen. The measurement Timeout otherwise no Flow Export would be seen. The measurement
duration SHOULD guarantee that the number of Cache entries created duration SHOULD guarantee that the number of Cache entries created
during the measurement exceeds the available Cache Size. during the measurement exceeds the available Cache Size.
5.3 Cache Population 5.3 Cache Population
The product of Inactive Timeout and the packet rate offered to the The product of Inactive Timeout and the packet rate offered to the
DUT (cache population) during the measurements determines the total DUT (cache population) during the measurements determines the total
number of Cache entries in the DUT Cache during one particular number of Cache entries in the DUT Cache during one particular
measurement (while taking into account some margin for dynamic measurement (while taking into account some margin for dynamic
behaviour during high DUT loads when processing the Flows). behaviour during high DUT loads when processing the Flows). Novak Novak Expires January, 2012
The Flow monitoring implementation might behave differently The Flow monitoring implementation might behave differently
depending on the relation of cache population to the available Cache depending on the relation of cache population to the available Cache
Size during the measurement. This behaviour is fully implementation Size during the measurement. This behaviour is fully implementation
specific and will also be influenced if the DUT is software based or specific and will also be influenced if the DUT is software based or
hardware based architecture. hardware based architecture.
The cache population (if it is lower or higher than the available The cache population (if it is lower or higher than the available
Cache Size) during a particular benchmark measurement SHOULD be Cache Size) during a particular benchmark measurement SHOULD be
noted and mainly only measurements with same cache population SHOULD noted and mainly only measurements with same cache population SHOULD
be compared. be compared.
5.4 Measurement Time Interval 5.4 Measurement Time Interval
The measurement time interval is the time value which is used to The measurement time interval is the time value which is used to
calculate the measured Flow Export Rate from the captured Flow calculate the measured Flow Export Rate from the captured Flow
Export data. It is obtained as specified below. Export data. It is obtained as specified below.
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RFC2544 specifies with the precision of the packet beginning and end RFC2544 specifies with the precision of the packet beginning and end
the time intervals to be used to measure the DUT time the time intervals to be used to measure the DUT time
characteristics. In the case of a Flow Monitoring Throughput characteristics. In the case of a Flow Monitoring Throughput
measurement the start and stop time needs to be clearly defined but measurement the start and stop time needs to be clearly defined but
the granularity of this definition can be limited to just marking the the granularity of this definition can be limited to just marking the
start and stop time with the start and stop of the traffic generator. start and stop time with the start and stop of the traffic generator.
This assumes that the traffic generator and DUT are collocated and This assumes that the traffic generator and DUT are collocated and
the variance in transmission delay from the generator to the DUT is the variance in transmission delay from the generator to the DUT is
negligible as compared to the total time of traffic generation. negligible as compared to the total time of traffic generation.
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possible to setup the traffic generator to send traffic for a certain possible to setup the traffic generator to send traffic for a certain
pre-defined time interval which is then used in the above definition pre-defined time interval which is then used in the above definition
instead of the difference (stop time) - (start time). instead of the difference (stop time) - (start time).
The Collector MUST stop collecting the Flow Export data at the The Collector MUST stop collecting the Flow Export data at the
measurement stop time. measurement stop time.
The Inactive Timeout (or the time needed to fill up the Cache) causes 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 delay of the Flow Export data behind the test traffic which is
analysed by the DUT. E.g. if the traffic starts at time point X Flow analysed by the DUT. E.g. if the traffic starts at time point X Flow
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Export will start only at the time point X + Inactive Timeout (or X + Export will start only at the time point X + Inactive Timeout (or X +
time to fill up the Cache). Since Flow Export capture needs to stop time to fill up the Cache). Since Flow Export capture needs to stop
with the traffic (because that's when the DUT stops processing the with the traffic (because that's when the DUT stops processing the
Flows at the given rate) the time interval during which the DUT kept Flows at the given rate) the time interval during which the DUT kept
exporting data is shorter by the Inactive Timeout than the Time exporting data is shorter by the Inactive Timeout than the Time
interval when the test traffic was sent from the traffic generator to interval when the test traffic was sent from the traffic generator to
the DUT. the DUT.
5.5 Flow Export Rate Measurement 5.5 Flow Export Rate Measurement
The Flow Export Rate needs to be measured in two consequent steps. 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 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 value for the rate, the second step (point b. below) needs to be done
in order to verify Flow Record drops during the measurement: in order to verify Flow Record drops during the measurement:
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a. In the first step the captured Flow Export data MUST be analyzed a. In the first step the captured Flow Export data MUST be analyzed
only for the capturing interval (measurement time interval) as only for the capturing interval (measurement time interval) as
specified in section 5.4. During this period the DUT is forced to specified in section 5.4. During this period the DUT is forced to
process Cache entries at the rate the packets are sent. When process Cache entries at the rate the packets are sent. When
traffic generation finishes, the behaviour when emptying the Cache traffic generation finishes, the behaviour when emptying the Cache
is completely implementation specific and the Flow Export data is completely implementation specific and the Flow Export data
from this period cannot be therefore used for the benchmarking. 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 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 captured in order to be capable to determine the Flow Record
losses. It needs to be taken into account that especially when losses. It needs to be taken into account that especially when
large Cache Sizes (in order of magnitude of hundreds of thousands large Cache Sizes (in order of magnitude of hundreds of thousands
of entries and higher) are in use the Flow Export can take many of entries and higher) are in use the Flow Export can take many
multiples of Inactive Timeout to empty the Cache after the multiples of Inactive Timeout to empty the Cache after the
measurement. This behaviour is completely implementation specific. measurement. This behaviour is completely implementation specific.
If the Collector has the capability to redirect the Flow Export data If the Collector has the capability to redirect the Flow Export data
after the measurement time interval into different capture buffer after the measurement time interval into different capture buffer
(or time stamp the received Flow Export data after that) this can be (or time stamp the received Flow Export data after that) this can be
done in one step. Otherwise each Flow Monitoring Throughput done in one step. Otherwise each Flow Monitoring Throughput
measurement at certain packet rate needs to be executed twice - once measurement at certain packet rate needs to be executed twice - once
to capture the Flow Export data just for the measurement time to capture the Flow Export data just for the measurement time
interval (to determine the actual Flow Export Rate) and second time interval (to determine the actual Flow Export Rate) and second time
to capture all Flow Export data in order to determine Flow Record to capture all Flow Export data in order to determine Flow Record
losses at that packet rate. losses at that packet rate.
At the end of the measurement time interval the DUT might still be At the end of the measurement time interval the DUT might still be
processing Cache entries which belong to the Flows expired from the processing Cache entries which belong to the Flows expired from the
Cache before the end of the interval while they will appear in an Cache before the end of the interval while they will appear in an
export packet sent only after the end of the measurement interval. export packet sent only after the end of the measurement interval.
This imprecision can be mitigated by large amounts of Flow Records This imprecision can be mitigated by large amounts of Flow Records
used during the measurement (so that the few Flow Records in one used during the measurement (so that the few Flow Records in one
export packet can be ignored) or by use of timestamps exported with export packet can be ignored) or by use of timestamps exported with
the Flow Records. the Flow Records.
5.6 The Measurement Procedure 5.6 The Measurement Procedure
The measurement procedure is same as the Throughput measurement in The measurement procedure is same as the Throughput measurement in
section 26.1 of [RFC2544] for the traffic sending side. The DUT section 26.1 of [RFC2544] for the traffic sending side. The DUT
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output analysis is done on the traffic generator receiving side for output analysis is done on the traffic generator receiving side for
the test traffic the same way as for RFC2544 measurements. the test traffic the same way as for RFC2544 measurements.
An additional analysis is performed using data captured by the An additional analysis is performed using data captured by the
Collector. The purpose of this analysis is to establish the value of Collector. The purpose of this analysis is to establish the value of
the Flow Export Rate during the current measurement step and to verify the Flow Export Rate during the current measurement step and to verify
that no Flow Records were dropped during the measurement. The that no Flow Records were dropped during the measurement. The
procedure to measure Flow Export Rate is described in section 5.5. procedure to measure Flow Export Rate is described in section 5.5.
The Flow Export performance can be significantly affected by the way The Flow Export performance can be significantly affected by the way
the Flow monitoring implementation formats the Flow Records into the the Flow monitoring implementation formats the Flow Records into the
Flow Export packets in terms of ordering and frequency of Control Flow Export packets in terms of ordering and frequency of Control
Information export and mainly the number of Flow Records in one Flow 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 Export packet. The worst case scenario here is just one Flow Record in
every Flow Export packet. every Flow Export packet.
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Flow Export data should be sanity checked during the benchmark Flow Export data should be sanity checked during the benchmark
measurement for: measurement for:
a. the number of Flow Records per packet, by simply calculating the a. the number of Flow Records per packet, by simply calculating the
ratio of exported Flow Records to the number of Flow Export ratio of exported Flow Records to the number of Flow Export
packets captured during the measurement (which should be available packets captured during the measurement (which should be available
as a counter on the Collector capture buffer) as a counter on the Collector capture buffer)
b. the number Flow Records corresponding to the export of Control b. the number Flow Records corresponding to the export of Control
Information per Flow Export packet (calculated as the ratio of the Information per Flow Export packet (calculated as the ratio of the
total number of such Flow Records in the Flow Export data and the total number of such Flow Records in the Flow Export data and the
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for the rest of RFC2544 network interconnect devices characteristics. for the rest of RFC2544 network interconnect devices characteristics.
Objective: Objective:
Provide RFC2544 network device characteristics in the presence of Provide RFC2544 network device characteristics in the presence of
Flow monitoring on the DUT. RFC2544 studies numerous Flow monitoring on the DUT. RFC2544 studies numerous
characteristics of network devices. The DUT forwarding and time characteristics of network devices. The DUT forwarding and time
characteristics without Flow monitoring present on the DUT can characteristics without Flow monitoring present on the DUT can
vary significantly when Flow monitoring is deployed on the network vary significantly when Flow monitoring is deployed on the network
device. device.
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Metric definition: Metric definition:
Metric as specified in [RFC2544]. Metric as specified in [RFC2544].
The measured RFC2544 Throughput MUST NOT include the packet rate The measured RFC2544 Throughput MUST NOT include the packet rate
corresponding to the Flow Export data, because it is control type corresponding to the Flow Export data, because it is control type
traffic, generated by the DUT as a result of enabling Flow monitoring traffic, generated by the DUT as a result of enabling Flow monitoring
and does not contribute to the test traffic which the DUT can handle. and does not contribute to the test traffic which the DUT can handle.
It requires DUT resources to be generated and transmitted and It requires DUT resources to be generated and transmitted and
therefore the RFC2544 Throughput in most cases will be much lower therefore the RFC2544 Throughput in most cases will be much lower
when Flow monitoring is enabled on the DUT than without it. when Flow monitoring is enabled on the DUT than without it.
6.1 Flow Monitoring Configuration 6.1 Flow Monitoring Configuration
Flow monitoring configuration (as detailed in section 4.3) needs Flow monitoring configuration (as detailed in section 4.3) needs
to be applied the same way as discussed in the section 5 with the to be applied the same way as discussed in the section 5 with the
exception of the Active Timeout configuration. exception of the Active Timeout configuration.
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The Active Timeout SHOULD be configured to exceed several times the The Active Timeout SHOULD be configured to exceed several times the
measurement time interval (see section 5.4). This makes sure that if measurement time interval (see section 5.4). This makes sure that if
measurements with two traffic components are performed (see section measurements with two traffic components are performed (see section
6.5) there is no Flow monitoring activity related to the second 6.5) there is no Flow monitoring activity related to the second
traffic component. traffic component.
The Flow monitoring configuration does not change in any other way The Flow monitoring configuration does not change in any other way
for the measurement performed in this section. What changes and makes for the measurement performed in this section. What changes and makes
the difference is the traffic configurations as specified in the the difference is the traffic configurations as specified in the
sections below. sections below.
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Export Rate lower than Flow Monitoring Throughput. Export Rate lower than Flow Monitoring Throughput.
The tester here has both options as specified in the section 6.4 and The tester here has both options as specified in the section 6.4 and
6.5. 6.5.
6.4 Measurements With Single Traffic Component 6.4 Measurements With Single Traffic Component
Section 12 of [RFC2544] discusses the use of protocol source and Section 12 of [RFC2544] discusses the use of protocol source and
destination addresses for defined measurements. To perform all the destination addresses for defined measurements. To perform all the
RFC2544 type measurements with Flow monitoring enabled the defined RFC2544 type measurements with Flow monitoring enabled the defined
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Flow Keys SHOULD contain IP source and destination address. The Flow Keys SHOULD contain IP source and destination address. The
RFC2544 type measurements with Flow monitoring enabled then can be RFC2544 type measurements with Flow monitoring enabled then can be
executed under these additional conditions: executed under these additional conditions:
a. the test traffic is not limited to single unique pair of source a. the test traffic is not limited to single unique pair of source
and destination addresses and destination addresses
b. the traffic generator defines test traffic as follows: b. the traffic generator defines test traffic as follows:
allow for a parameter to send N (where N is an integer number allow for a parameter to send N (where N is an integer number
starting at 1 and incremented in small steps) packets with source starting at 1 and incremented in small steps) packets with source
IP address A and destination IP address B before changing both IP IP address A and destination IP address B before changing both IP
addresses to the next value addresses to the next value
This test traffic definition allows execution of the Flow monitoring This test traffic definition allows execution of the Flow monitoring
measurements with fixed Flow Export Rate while measuring the DUT measurements with fixed Flow Export Rate while measuring the DUT
RFC2544 characteristics. This set-up is the better option since it RFC2544 characteristics. This set-up is the better option since it
best simulates the live network traffic scenario with Flows best simulates the live network traffic scenario with Flows
containing more than just one packet. containing more than just one packet.
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The initial packet rate at N equal to 1 defines the Flow Export Rate The initial packet rate at N equal to 1 defines the Flow Export Rate
for the whole measurement procedure. Subsequent increases of N will for the whole measurement procedure. Subsequent increases of N will
not change the Flow Export Rate as the time and Cache not change the Flow Export Rate as the time and Cache
characteristics of the test traffic stay the same. This set-up is characteristics of the test traffic stay the same. This set-up is
suitable for measurements with Flow Export Rates below the Flow suitable for measurements with Flow Export Rates below the Flow
Monitoring Throughput. Monitoring Throughput.
6.5 Measurements With Two Traffic Components 6.5 Measurements With Two Traffic Components
The test traffic set-up in section 6.4 might be difficult to achieve The test traffic set-up in section 6.4 might be difficult to achieve
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addresses). addresses).
The Flow monitoring traffic component will exercise the DUT in terms The Flow monitoring traffic component will exercise the DUT in terms
of Flow activity while the second traffic component will measure the of Flow activity while the second traffic component will measure the
RFC2544 characteristics. RFC2544 characteristics.
The measured RFC2544 Throughput is the sum of the packet rates of The measured RFC2544 Throughput is the sum of the packet rates of
both traffic components. The definition of other RFC2544 metrics both traffic components. The definition of other RFC2544 metrics
remains unchanged. remains unchanged.
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7. Flow Monitoring Accuracy 7. Flow Monitoring Accuracy
The pure Flow Monitoring Throughput measurement in section 5 provides The pure Flow Monitoring Throughput measurement in section 5 provides
The capability to verify the Flow monitoring accuracy in terms of the The capability to verify the Flow monitoring accuracy in terms of the
exported Flow Record data. Since every Cache entry created in the exported Flow Record data. Since every Cache entry created in the
Cache is populated by just one packet, the full set of captured data 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 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 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 count in the exported data) and each set of parameters from each Flow
Record can be checked against the parameters as configured on the Record can be checked against the parameters as configured on the
traffic generator and set in packets sent to the DUT. The exported traffic generator and set in packets sent to the DUT. The exported
Flow Record is considered accurate if: Flow Record is considered accurate if:
a. all the Flow Record fields are present in each exported Flow a. all the Flow Record fields are present in each exported Flow
Record Record
b. all the Flow Record fields values match the value ranges as set by 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 the traffic generator (for example an IP address falls within the
range of the IP addresses increments on the traffic generator) range of the IP addresses increments on the traffic generator)
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c. all the possible Flow Record fields values as defined at the c. all the possible Flow Record fields values as defined at the
traffic generator have been found in the captured export data traffic generator have been found in the captured export data
on the Collector. This check needs to be offset against detected on the Collector. This check needs to be offset against detected
packet losses at the DUT during the measurement 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 8. Evaluating Flow Monitoring Applicability
The measurement results as discussed in this document and obtained The measurement results as discussed in this document and obtained
for certain DUTs allow for a preliminary analysis of a Flow for certain DUTs allow for a preliminary analysis of a Flow
monitoring deployment based on the traffic analysis data from the monitoring deployment based on the traffic analysis data from the
providers network. providers network.
An example of such traffic analysis in the Internet is provided by 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 [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 needed to make an estimate if a certain network device can manage the
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Expected packet rate Expected packet rate
Flows per second = -------------------- Flows per second = --------------------
Packet per flow Packet per flow
When using the example values given above, the network device would When using the example values given above, the network device would
Be required to process 18 000 Flows per second. By executing the Be required to process 18 000 Flows per second. By executing the
benchmarking as specified in this document a platform capable of this benchmarking as specified in this document a platform capable of this
processing can be determined for the deployment in that particular processing can be determined for the deployment in that particular
part of the user network. part of the user network.
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It needs to be kept in mind that the above is a very rough and It needs to be kept in mind that the above is a very rough and
averaged Flow activity estimate which cannot account for traffic averaged Flow activity estimate which cannot account for traffic
anomalies, for example a large number of DNS request packets which anomalies, for example a large number of DNS request packets which
are typically small packets coming from many different sources and are typically small packets coming from many different sources and
represent mostly just one packet per Flow. represent mostly just one packet per Flow.
9. Acknowledgements 9. Acknowledgements
This work could have been performed thanks to the patience and This work could have been performed thanks to the patience and
support of Cisco Systems NetFlow development team, namely Paul support of Cisco Systems NetFlow development team, namely Paul
Aitken, Paul Atkins and Andrew Johnson. Thanks belong to Benoit Aitken, Paul Atkins and Andrew Johnson. Thanks belong to Benoit
Claise for numerous detailed reviews and presentations of the Claise for numerous detailed reviews and presentations of the
document and Aamer Akhter for initiating this work. A special document and Aamer Akhter for initiating this work. A special
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acknowledgment needs to go to the whole of the working group and acknowledgment needs to go to the whole of the working group and
especially to the chair Al Morton for the support and work on especially to the chair Al Morton for the support and work on
this draft and to Paul Aitken for a very detailed technical this draft and to Paul Aitken for a very detailed technical
review. review.
10. Security Considerations 10. Security Considerations
Documents of this type do not directly affect the security of Documents of this type do not directly affect the security of
the Internet or corporate networks as long as benchmarking the Internet or corporate networks as long as benchmarking
is not performed on devices or systems connected to operating is not performed on devices or systems connected to operating
skipping to change at page 27, line 44 skipping to change at page 26, line 57
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, April 1997 Requirement Levels", BCP 14, RFC 2119, April 1997
[RFC2544] Bradner, S., "Benchmarking Methodology for Network [RFC2544] Bradner, S., "Benchmarking Methodology for Network
Interconnect Devices", Informational, RFC 2544, April 1999 Interconnect Devices", Informational, RFC 2544, April 1999
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[RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek, [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
"Architecture Model for IP Flow Information Export", "Architecture Model for IP Flow Information Export",
RFC 5470, June 2011 RFC 5470, July 2011
11.2. Informative References 11.2. Informative References
[RFC1242] Bradner, S., "Benchmarking Terminology for Network [RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, July 1991 Interconnection Devices", RFC 1242, July 1991
[RFC2285] Mandeville R., "Benchmarking Terminology for LAN Switching [RFC2285] Mandeville R., "Benchmarking Terminology for LAN Switching
Devices", Informational, RFC 2285, November 1998 Devices", Informational, RFC 2285, November 1998
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[RFC3031] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label [RFC3031] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label
Switching Architecture", Standards Track, RFC 3031, Switching Architecture", Standards Track, RFC 3031,
January 2001 January 2001
[RFC3917] Quittek J., "Requirements for IP Flow Information Export [RFC3917] Quittek J., "Requirements for IP Flow Information Export
(IPFIX)", Informational, RFC 3917, October 2004. (IPFIX)", Informational, RFC 3917, October 2004.
[RFC5101] Claise B., "Specification of the IP Flow Information [RFC5101] Claise B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", Standards Track, RFC 5101, January 2008 Flow Information", Standards Track, RFC 5101, January 2008
[RFC5180] C. Popoviciu, A. Hamza, D. Dugatkin, G. Van de Velde, [RFC5180] C. Popoviciu, A. Hamza, D. Dugatkin, G. Van de Velde,
"IPv6 Benchmarking Methodology for Network Interconnect "IPv6 Benchmarking Methodology for Network Interconnect
Devices", Informational, RFC 5180, May 2008 Devices", Informational, RFC 5180, May 2008
[RFC5475] T. Zseby, M. Molina, N. Duffield, F. Raspall, "Sampling
and Filtering Techniques for IP Packet Selection"
RFC 5475, March 2009
[RFC5476] Claise, B., Quittek, J., and A. Johnson, "Packet
Sampling (PSAMP) Protocol Specifications", RFC 5476,
March 2009
[RFC5695] Akhter A. "MPLS Forwarding Benchmarking Methodology", [RFC5695] Akhter A. "MPLS Forwarding Benchmarking Methodology",
RFC 5695, November 2009 RFC 5695, November 2009
[CAIDA] Claffy, K., "The nature of the beast: recent traffic [CAIDA] Claffy, K., "The nature of the beast: recent traffic
measurements from an Internet backbone", measurements from an Internet backbone",
http://www.caida.org/publications/papers/1998/Inet98/ http://www.caida.org/publications/papers/1998/Inet98/
Inet98.html Inet98.html
Author's Addresses Author's Addresses
Jan Novak (editor) Jan Novak (editor)
Cisco Systems Cisco Systems
Edinburgh, Edinburgh,
United Kingdom United Kingdom
Email: janovak@cisco.com Email: janovak@cisco.com
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Appendix A: Recommended Report Format Appendix A: Recommended Report Format
Parameter Units Parameter Units
----------------------------------- ------------------------------------ ----------------------------------- ------------------------------------
Test Case test case name (section 5 and 6) Test Case test case name (section 5 and 6)
Test Topology Figure 2, other Test Topology Figure 2, other
Traffic Type IPv4, IPv6, MPLS, other Traffic Type IPv4, IPv6, MPLS, other
Test Results Test Results
Flow Monitoring Throughput Flow Records per second or Not Flow Monitoring Throughput Flow Records per second or Not
Applicable Applicable
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Cache Size number of entries Cache Size number of entries
Active Timeout seconds Active Timeout seconds
Inactive Timeout seconds Inactive Timeout seconds
Flow Keys list of fields Flow Keys list of fields
Flow Record Fields total number of fields Flow Record Fields total number of fields
Number of Flows Created number of entries Number of Flows Created number of entries
Flow Export Transport Protocol UDP, TCP, SCTP, other Flow Export Transport Protocol UDP, TCP, SCTP, other
Flow Export Protocol IPFIX, NetFlow, other Flow Export Protocol IPFIX, NetFlow, other
Flow Export data packet size bytes 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) MPLS Specifications (for traffic type MPLS only)
Tested Label Operation imposition, swap, disposition Tested Label Operation imposition, swap, disposition
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Appendix B: Miscellaneous Tests Appendix B: Miscellaneous Tests
This section lists the tests which could be useful to asses a proper This section lists the tests which could be useful to asses a proper
Flow monitoring operation under various operational or stress Flow monitoring operation under various operational or stress
conditions. These tests are not deemed suitable for any benchmarking conditions. These tests are not deemed suitable for any benchmarking
for various reasons. for various reasons.
B.1 DUT Under Traffic Load B.1 DUT Under Traffic Load
The Flow Monitoring Throughput SHOULD be measured under different The Flow Monitoring Throughput SHOULD be measured under different
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The expected result is that the RFC2544 Throughput achieved in The expected result is that the RFC2544 Throughput achieved in
step a. is same as the Throughput achieved in step d. provided step a. is same as the Throughput achieved in step d. provided
that the bandwidth of the output DUT interface is not the that the bandwidth of the output DUT interface is not the
bottleneck (in other words it must have enough capacity to bottleneck (in other words it must have enough capacity to
forward both test and Flow Export traffic). forward both test and Flow Export traffic).
B.3 Variable Packet Size B.3 Variable Packet Size
The Flow monitoring measurements specified in this document would The Flow monitoring measurements specified in this document would
be interesting to repeat with variable packet sizes within one be interesting to repeat with variable packet sizes within one
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particular test (e.g. test traffic containing mix of packet particular test (e.g. test traffic containing mix of packet
sizes). The packet forwarding tests specified mainly in [RFC2544] sizes). The packet forwarding tests specified mainly in [RFC2544]
do not recommend and perform such tests. Flow monitoring is not do not recommend and perform such tests. Flow monitoring is not
dependent on packet sizes so such a test could be performed during dependent on packet sizes so such a test could be performed during
the Flow Monitoring Throughput measurement and verify its value the Flow Monitoring Throughput measurement and verify its value
does not depend on the offered traffic packet sizes. The tests does not depend on the offered traffic packet sizes. The tests
must be carefully designed in order to avoid measurement errors must be carefully designed in order to avoid measurement errors
due to the physical bandwidth limitations and changes of the base due to the physical bandwidth limitations and changes of the base
forwarding performance with packet size. forwarding performance with packet size.
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The performance measurement of a DUT in such a configuration The performance measurement of a DUT in such a configuration
represents an useful test of the DUT capabilities (this represents an useful test of the DUT capabilities (this
corresponds to the case when the network operator uses Flow corresponds to the case when the network operator uses Flow
monitoring for example for manual denial of service attacks monitoring for example for manual denial of service attacks
detection and does not wish to use Flow Export). detection and does not wish to use Flow Export).
The performance testing on this DUT can be performed as discussed The performance testing on this DUT can be performed as discussed
in this document but it is not possible to verify the operation in this document but it is not possible to verify the operation
and results without interrogating the DUT. and results without interrogating the DUT.
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B.5.3 RFC2544 Throughput with Metering and Exporting Process B.5.3 RFC2544 Throughput with Metering and Exporting Process
This test represents the performance testing as discussed in This test represents the performance testing as discussed in
section 6. section 6.
B.6 Tests With Bidirectional Traffic B.6 Tests With Bidirectional Traffic
The test topology on figure 2 can be expanded to verify Flow The test topology on figure 2 can be expanded to verify Flow
monitoring functionality with bidirectional traffic in two possible monitoring functionality with bidirectional traffic in two possible
ways: ways:
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time interval than specified in the section 5.4) Flow Export Rate time interval than specified in the section 5.4) Flow Export Rate
b. The Flow Export protocol (like IPFIX [RFC5101]) can provide time b. The Flow Export protocol (like IPFIX [RFC5101]) can provide time
stamps in the Flow Export packets which would allow time based stamps in the Flow Export packets which would allow time based
analysis and calculate the Flow Export Rate as an average over analysis and calculate the Flow Export Rate as an average over
much shorter time interval than specified in the section 5.4 much shorter time interval than specified in the section 5.4
The accuracy and shortest time average will always be limited by the The accuracy and shortest time average will always be limited by the
precision of the time stamps (1 second for IPFIX) or by the precision of the time stamps (1 second for IPFIX) or by the
capabilities of the DUT and the Collector. capabilities of the DUT and the Collector.
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