Network Working Group                           Jerry Perser
     INTERNET-DRAFT                                  Spirent
     Expires in: May December 2002                       David Newman
                                                     Network Test
                                                     Sumit Khurana
                                                     Telcordia
                                                     Shobha Erramilli
                                                     QNetworx
                                                     Scott Poretsky
                                                     Avici Systems
                                                     November 2001
                                                     June 2002

                 Terminology for Benchmarking Network-layer
                         Traffic Control Mechanisms

                      <draft-ietf-bmwg-dsmterm-02.txt>

                      <draft-ietf-bmwg-dsmterm-03.txt>

     Status of this Memo

     This document is an Internet-Draft and is in full conformance with
     all provisions of Section 10 of RFC2026.

     Internet-Drafts are working documents of the Internet Engineering
     Task Force  (IETF), its areas, and its working groups.  Note that
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     Drafts.

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     Drafts as reference material or to cite them other than as "work
     in progress."

     The list of current Internet-Drafts can be accessed at
     http://www.ietf.org/ietf/1id-abstracts.txt

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     Table of Contents

        1. Introduction  .............................................. 2
        2. Existing definitions  ...................................... 3
        3. Term definitions ............................................3
        3.1 Configuration Terms
          3.1.1 Classification .........................................3
          3.1.2 Codepoint Set ..........................................4
          3.1.3 Congestion .............................................4
          3.1.4 Congestion Management ..................................5
          3.1.5 Flow ...................................................6
        3.2 Vectors ....................................................6
          3.2.1 Intended Vector ........................................6 Measurement Terms
                 Network-layer Traffic Control Mechanisms

          3.2.1 Channel Capacity .......................................7
          3.2.2 Conforming .............................................7
          3.2.3 Nonconforming ..........................................8
          3.2.4 Delay ..................................................8
        3.2.6 Undifferentiated Response ................................9
        3.3 Sequence Tracking
          3.3.1 In-sequence Packet .....................................9
          3.3.2 Out-of-order Packet ...................................10
          3.3.3 Duplicate Packet ......................................11
          3.3.4 Stream ................................................11
          3.3.5 Test Sequence number  .................................12
        3.4 Vectors ...................................................12
          3.4.1 Intended Vector .......................................12
          3.4.2 Offered Vector .........................................6
          3.2.3 ........................................13
          3.4.3 Expected Vectors
          3.2.3.1
            3.4.3.1 Expected Forwarding Vector ...........................7
          3.2.3.2 ........................13
            3.4.3.2 Expected Loss Vector .................................8
          3.2.3.3 ..............................14
            3.4.3.3 Expected Sequence Vector .............................8
          3.2.3.4 ..........................14
            3.4.3.4 Expected Instantaneous Delay Vector ................................9
          3.2.3.5 ...............15
            3.4.3.5 Expected Jitter Average Delay Vector ..............................10
          3.2.4 .....................16
            3.4.3.6 Expected Maximum Delay Vector .....................17
            3.4.3.7 Expected Minimum Delay Vector .....................17
            3.4.3.8 Expected Instantaneous Delay Variation Vector .....18
            3.4.3.9 Expected Average Delay Variation Vector ...........19
            3.4.3.10 Expected Peak-to-peak Delay Variation Vector .....19
          3.4.4 Output Vectors
          3.2.4.1
            3.4.4.1 Forwarding Vector ...................................11
          3.2.4.2 .................................20
            3.4.4.2 Loss Vector .........................................11
          3.2.4.3 .......................................20
            3.4.4.3 Sequence Vector .....................................12
          3.2.4.4 ...................................21
            3.4.4.4 Instantaneous Delay Vector ........................................13
          3.2.4.5 Jitter ........................22
            3.4.4.5 Average Delay Vector .......................................14
        3.3 Measurement Terms
          3.3.1 Channel Capacity ......................................15
          3.3.2 Conforming ............................................15
          3.3.3 Nonconforming .........................................16
          3.3.4 ..............................23
            3.4.4.6 Maximum Delay .................................................16
          3.3.5 Flow ..................................................17
          3.3.6 Stream ................................................18
          3.3.7 Test Sequence number ..................................19
          3.3.8 Undifferentiated Response .............................19 Vector ..............................23
            3.4.4.7 Minimum Delay Vector ..............................24
            3.4.4.8 Instantaneous Delay Variation Vector ..............25
            3.4.4.9 Average Delay Variation Vector ....................26
            3.4.4.10 Peak-to-peak Delay Variation Vector ..............27
        4. Security Considerations ....................................20 ....................................28
        5. References .................................................20 .................................................28
        6. Author's Address ...........................................21 ...........................................29
        7. Full Copyright Statement ...................................22 ...................................30

     1. Introduction

     This document describes terminology for the benchmarking of
     devices that implement traffic control based on IP precedence or
     diff-serv code point criteria.

     New terminology is needed because most existing measurements
     assume the absence of congestion and only a single per-hop-
     behavior. This document introduces several new terms that will
     allow measurements to be taken during periods of congestion.

                 Network-layer Traffic Control Mechanisms

     Another key difference from existing terminology is the definition
     of measurements as observed on egress as well as ingress of a
     device/system under test. Again, the existence of congestion
     requires the addition of egress measurements as well as those
     taken on ingress; without observing traffic leaving a
     device/system it is not possible to say whether traffic-control
     mechanisms effectively dealt with congestion.

     The principal measurements introduced in this document are vectors
     for rate, delay, and jitter, all of which can be observed with or
     without congestion of the DUT/SUT.

                 Network-layer Traffic Control Mechanisms

     This document describes only those terms relevant to measuring
     behavior of a device or a group of devices using one of these two
     mechanisms. End-to-end and service-level measurements are beyond
     the scope of this document.

     2.  Existing definitions

     RFC 1242 "Benchmarking Terminology for Network Interconnect
     Devices" and RFC 2285 "Benchmarking Terminology for LAN Switching
     Devices" should be consulted before attempting to make use of this
     document.

     RFC 2474 "Definition of the Differentiated Services Field (DS
     Field) in the IPv4 and IPv6 Headers" section 2, contains
     discussions of a number of terms relevant to network-layer traffic
     control mechanisms and should also be consulted.

     For the sake of clarity and continuity this RFC adopts the
     template for definitions set out in Section 2 of RFC 1242.
     Definitions are indexed and grouped together in sections for ease
     of reference.

     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.

     3. Term definitions

     3.1 Configuration Terms

     3.1.1 Classification

        Definition:
          Selection of packets based on the contents of packet header
          according to defined rules.

                 Network-layer Traffic Control Mechanisms

        Discussion:
          Packets can be selected based on the DS field or IP
          Precedence in the packet header.  Classification can also be
          based on Multi-Field (MF) criteria such as IP Source and
          destination addresses, protocol and port number.

          Classification determines the per-hop behaviors and traffic
          conditioning functions such as shaping and dropping that are
          to be applied to the packet.

        Measurement units:

                 Network-layer Traffic Control Mechanisms
           n/a

        Issues:

        See Also:

     3.1.2 Codepoint Set

        Definition:
          The set of all DS Code-points or IP precedence values used
          during the test duration.

        Discussion:
          Describes all the code-point markings associated with packets
          that are input to the DUT/SUT.  For each entry in the
          codepoint set, there are associated vectors describing the
          rate of traffic traffic, delay, loss, or jitter containing that
          particular DSCP or IP precedence value.

          The treatment that a packet belonging to a particular code-
          point gets is subject to the DUT classifying packets to map
          to the correct PHB. Moreover, the forwarding treatment in
          general is also dependent on the complete set of offered
          vectors.

        Measurement Units:
          n/a

        See Also:

     3.1.3 Congestion

        Definition:
          A condition in which one or more egress interfaces are
          offered more packets than are forwarded at any given instant.

        Discussion:
          This condition is a superset of the overload definition [2].
          The overload definition assumes the congestion is introduced
                 Network-layer Traffic Control Mechanisms

          strictly by the tester on ingress of a DUT/SUT. That may or
          may not be the case here.

          Another difference is between congestion and overload occurs
          when the SUT comprises multiple elements, in that with multiple-DUT measurements, congestion
          may occur at multiple points. For example, Consider an SUT comprising
          multiple edge devices collectively may congest exchanging traffic with a single core
          device. Depending on traffic patterns, the edge devices may
          induce congestion on multiple egress interfaces on the core
          device. In contrast, overload [1] deals only with overload on
          ingress.

                 Network-layer Traffic Control Mechanisms

          Ingress observations alone are not sufficient to cover all
          cases in which congestion may occur. A device with an
          infinite amount of memory could buffer an infinite amount of
          packets, and eventually forward all of them. However, these
          packets may or may not be forwarded during the test duration.
          Even though ingress interfaces accept all packets without
          loss, this hypothetical device may still be congested.

          The definition presented here explicitly defines congestion
          as an event observable on egress interfaces. Regardless of
          internal architecture, any device that cannot forward packets
          on one or more egress interfaces is congested.

        Measurement units:
           n/a

        Issues:

        See Also:

     3.1.4 Congestion Management

        Definition:
          An implementation of one or more per-hop-behaviors to avoid
          or minimize the condition of congestion.

        Discussion:
          Congestion management may seek either to control congestion
          or avoid it altogether. Such mechanisms classify packets
          based upon IP Precedence or DSCP settings in a packet's IP
          header.

          Congestion avoidance mechanisms seek to prevent congestion
          before it actually occurs.

          Congestion control mechanisms gives one or more service
          classes flows (with a
          discrete IP Precedence or DSCP value) preferential treatment
          over other classes during periods of congestion.

        Measurement units:
           n/a

        Issues:

        See Also:
                 Network-layer Traffic Control Mechanisms

     3.2 Vectors

        See Also:

     3.1.5 Flow

        Definition:
          A vector flow is a group one or more of packets all containing a specific DSCP
          or IP precedence value.  Vectors are expressed as sharing a common intended
          pair of
          numbers.  The first is being the particular diff-serv value.
          The second is source and destination interfaces.

        Discussion:
          Packets are grouped by the metric expressed as ingress and egress interfaces they
          use on a rate, loss
          percentage, delay, or jitter.

     3.2.1 Intended Vector

        Definition: given DUT/SUT.

          A vector describing the rate at which packets having a
          specific code-point (or IP precedence) that an external flow can contain multiple source attempts to transmit to IP addresses and/or
          destination IP addresses.  All packets in a DUT/SUT.

        Discussion:
          Intended loads across flow must enter
          on the different code-point classes
          determine same ingress interface and exit on the metrics associated with same egress
          interface, and have some common network layer content.

          Microflows [3] are a specific code-point
          traffic class. subset of flows.  As defined in [3],
          microflows require application-to-application measurement. In
          contrast, flows use lower-layer classification criteria.
          Since this document focuses on network-layer classification
          criteria, we concentrate here on the use of network-layer
          identifiers in describing a flow. Flow identifiers also may
          reside at the data-link, transport, or application layers of
          the ISO model. However, identifiers other than those at the
          network layer are out of scope for this document.

          A flow may contain a single code point/IP precedence value or
          may contain multiple values destined for a single egress
          interface.  This is determined by the test methodology.

        Measurement Units:
          N-octets packets per second

        Issues: units:
           n/a

        See Also:
          Offered Vector
          Expected Forwarding Vector
          Expected Loss Vector
          Expected Sequence Vector
          Expected Delay Vector
          Expected Jitter Vector
          Forwarding Vector
          Loss Vector

     3.2.2 Offered Vector
          Microflow [3]
          Streams
                 Network-layer Traffic Control Mechanisms

     3.2 Measurement Terms

     3.2.1 Channel Capacity

        Definition:
          A vector describing the measured
          The maximum forwarding rate [2] at which none of the offered
          packets having
          a specific DSCP or IP precedence value are offered to dropped by the DUT/SUT.

        Discussion:
          Offered loads across
          Channel capacity measures the different code-point classes,
          constituting a code-point set, determine packet rate at the metrics
          associated with a specific code-point traffic class.

        Measurement Units:
          N-octets packets per second
                 Network-layer Traffic Control Mechanisms

        Issues:
          Packet size.

        See Also:
          Expected Forwarding Vector
          Expected Loss Vector
          Expected Sequence Vector
          Expected Delay Vector
          Expected Jitter Vector
          Forwarding Vector
          Codepoint Set

     3.2.3 Expected Vectors

     3.2.3.1 Expected Forwarding Vector

        Definition:
          A vector describing egress
          interface(s) of the expected output DUT/SUT. In contrast, throughput as
          defined in RFC 1242 measures the packet rate of packets
          having a specific DSCP or IP precedence value.  The value is
          dependent based on the set
          ingress interface(s) of offered vectors and configuration the DUT/SUT.

          Ingress-based measurements do not account for congestion of
          the DUT.

        Discussion:
          The DUT DUT/SUT. Channel capacity, as an egress measurement, does
          take congestion into account.

          Understanding channel capacity is configured in a certain way in order that service
          differentiation occurs for behavior aggregates when a
          specific traffic mix consisting necessary precursor to
          any measurement involving congestion.  Throughput numbers can
          be higher than channel capacity because of multiple behavior
          aggregates is applied. queueing.

          This term attempts to capture the
          expected measurement differs from forwarding behavior, for which the device is
          configured, when subjected to a certain rate at maximum
          offered load.

          The actual algorithms or mechanism, load (FRMOL) [2] in that the DUT uses to
          achieve service differentiation, it is not important in
          describing the expected vector. intolerant of loss.

        Measurement units:
           N-octet packets per second

        Issues:

        See Also:
          Intended Vector
          Throughput [1]
          Forwarding Rate at Maximum Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Delay Vector
          Expected Jitter Vector
                 Network-layer Traffic Control Mechanisms

     3.2.3.2 Expected Loss Vector Load [2]

     3.2.2 Conforming

        Definition:
          A vector describing the percentage of packets, having a
          Packets which lie within specific DSCP rate, delay, or IP precedence value, that should not be
          forwarded.  The value is dependent on the set of offered
          vectors and configuration of the DUT. jitter
          bounds.

        Discussion:
          The DUT is
          A DUT/SUT may be configured in a certain way in order that service
          differentiation occurs for behavior aggregates when to allow a
          specific given traffic mix consisting of multiple behavior
          aggregates is applied.  This term attempts to capture the
          expected loss behavior, for which the device is configured,
          when subjected class to
          consume a certain offered load.

          The actual algorithms given amount of bandwidth, or to fall within
          predefined delay or mechanism, jitter boundaries. All packets that the DUT uses lie
          within specified bounds are then said to
          achieve service differentiation, is not important in
          describing be conforming,
          whereas those outside the expected loss vector. bounds are nonconforming.

        Measurement Units:
          Percentage units:
           n/a

        See Also:
          Expected Vector
                 Network-layer Traffic Control Mechanisms

          Forwarding Vector
          Offered Vector
          Nonconforming

     3.2.3 Nonconforming

        Definition:
          Packets that do not lie within specific rate, delay, or
          jitter bounds.

        Discussion:
          A DUT/SUT may be configured to allow a given traffic class to
          consume a given amount of intended bandwidth, or to fall within
          predefined delay or jitter boundaries. All packets that do
          not lie within these bounds are expected then said to be
          dropped.

        Issues:
          nonconforming.

        Measurement units:
           n/a

        See Also:
          Intended Vector
          Offered Vector
          Expected Vector
          Forwarding Vector
          Expected Sequence
          Offered Vector
          Expected
          Conforming

     3.2.4 Delay Vector
          Expected Jitter Vector

     3.2.3.3 Expected Sequence Vector

        Definition:
          A vector describing
          The time interval starting when the expected sequencing last bit of packets having
          a specific DSCP or the input IP precedence value. The value is
          dependent on
          packet reaches the set input port of offered vectors the DUT/SUT and configuration ending when
          the last bit of the DUT.

        Discussion:
          The DUT is configured in a certain way in order that service
          differentiation occurs for behavior aggregates when a
          specific traffic mix consisting of multiple behavior
          aggregates is applied. This term attempts to capture the
          expected sequence behavior, for which the device output IP packet is
          configured, when subjected to a certain offered load.

                 Network-layer Traffic Control Mechanisms

          The actual algorithms or mechanism, that seen on the DUT uses to
          achieve service differentiation, is not important in
          describing output
          port of the expected vector.

        Measurement Units:
          N-octet packets per second

        Issues:

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Forwarding Vector
          Expected Delay Vector
          Expected Jitter Vector

     3.2.3.4 Expected DUT/SUT.

        Discussion:
          Delay Vector

        Definition:
          A vector describing the expected delay for packets having a
          specific DSCP or IP precedence value. The value is dependent
          on measured the set same regardless of offered vectors and configuration the type of DUT/SUT.
          Latency [1] require some knowledge of whether the DUT.

        Discussion:
          The DUT DUT/SUT is configured in
          a certain way in order "store and forward" or a "bit forwarding" device.  The fact
          that service
          differentiation occurs for behavior aggregates when a
          specific traffic mix consisting of multiple behavior
          aggregates is applied. This term attempts DUT/SUT's technology has a lower delay than another
          technology should be visible.

          By specifying the metric to capture be inside the
          expected delay behavior, for which Internet protocol,
          the device tester is configured,
          when subjected to a certain offered load.

          The actual algorithms or mechanism, relieved from specifying the start/end for
          every data link layer protocol that IP runs on.  This avoids
          determining if the DUT uses to
          achieve service differentiation, is not important start/end delimiters are included in
          describing the expected delay vector.

     Measurement units:

          Seconds.

        Issues:

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Forwarding Vector
          Expected Jitter Vector
          frame.  Also heterogeneous data link protocol can be used in
          a test.

          The measurement point at the end closely simulates the way an
          internet datagram is processed.  An internet datagram is not
                 Network-layer Traffic Control Mechanisms

     3.2.3.5 Expected Jitter Vector

        Definition:
          A vector describing

          passed up or down the expected variation in stack unless it is complete.
          Completion occurs once the delay last bit of the IP packet arrival times for packets having specific DSCP has been
          received.

          Delay can be run at any offered load.  Recommend at or IP
          precedence value. The value is dependent on below
          the channel capacity for non-congested delay.  For congested
          delay, run the set of offered vectors and configuration of load above the DUT. channel capacity.

        Measurement units:
           Seconds.

        See Also:
          Latency [1]

     3.2.6 Undifferentiated Response

        Definition:
          The vector(s) obtained when mechanisms used to support diff-
          serv or IP precedence are disabled.

        Discussion:
          Jitter is the absolute value of the difference between the
          delay measurement of two packets
          Enabling diff-serv or IP precedence mechanisms may impose
          additional processing overhead for packets. This overhead may
          degrade performance even when traffic belonging to only one
          class, the same
          stream.

          The jitter between two consecutive packets in a stream best-effort class, is
          reported as offered to the "instantaneous jitter". Instantaneous jitter device.

          Measurements with "undifferentiated response" should be made
          to establish a baseline.

          The vector(s) obtained with DSCPs or IP precedence enabled
          can be expressed as |D(i) - D(i-1)| where D equals compared to the delay
          and i is undifferentiated response to determine
          the test sequence number.  Packets lost are not
          counted in effect of differentiating traffic.

        Measurement units:
          n/a

     3.3 Sequence Tracking

     3.3.1 In-sequence Packet

        Definition:
          A received packet with the jitter measurement.

          Average Jitter expected Test Sequence number.

        Discussion:
          In-sequence is done on a stream level. As packets are
          received on a stream, each packet's Test Sequence number is
          compared with the average of previous packet.  Only packets that match
          the instantaneous jitter
          measured during expected are considered in-sequence.

                 Network-layer Traffic Control Mechanisms

          Packets that do not match the test duration.

          Peak-to-peak jitter expected Test Sequence number
          are counted as _not in-sequence_ or out-of-sequence.  Every
          packet that is received is either in-sequence or out-of-
          sequence.  Subtracting the maximum delay minus the minimum
          delay of in-sequence from the received
          packets forwarded by (for that stream) can derive the DUT/SUT. out-of-sequence
          count.

          Two types of events will prevent the in-sequence from
          incrementing: packet loss and reordered packets.

        Measurement units:
          Seconds (instantaneous)
          Seconds P-P (peak to peak)
          Seconds Avg (average)

        Issues:
          Packet count

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected
          Stream
          Test Sequence Vector
          Expected Delay Vector
          Expected Forwarding Vector

     3.2.4 Output Vectors
                 Network-layer Traffic Control Mechanisms

     3.2.4.1 Forwarding Vector number

     3.3.2 Out-of-order Packet

        Definition:
          The
          A received packet with a Test Sequence number less that
          expected.

        Discussion:
          As a stream of packets per second for all packets containing enter a
          specific DSCP or IP precedence value that DUT/SUT, they include a device can be
          observed to successfully transmit Stream
          Test Sequence number indicating the order the packets were
          sent to the correct destination
          interface DUT/SUT.  On exiting the DUT/SUT, these packets
          may arrive in response to an offered vector.

        Discussion:
          Forwarding Vector a different order.  Each packet that was re-
          ordered is expressed counted as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND an Out-of-order Packet.

          Certain streaming protocol (such as TCP) require the packets per
          second value combine
          to make be in a vector. certain order.  Packets outside this are dropped
          by the streaming protocols even though there were properly
          received by the IP layer.  The Forwarding Vector represents packet rate based on its
          specific DSCP (or IP precedence) value.  It type of reordering tolerated
          by a streaming protocol varies from protocol to protocol, and
          also by implementation.

          Out-of-order Packet count is not
          necessarily based on a stream or flow.  The Forwarding Vector
          may be expressed as per port of the DUT/SUT. However, it must
          be consistent with worst case
          streaming protocol.  It allows for no reordering.

          Packet loss does not affect the Expected Forwarding Vector.

          Forwarding Vector is a per-hop measurement.  The DUT/SUT may
          change Out-of-order Packet count.
          Only packets that were not received in the specific DSCP (or IP precedence) value for order that they
          were transmitted.

        Measurement units:
          Packet count

        See Also:
          Stream
          Test Sequence number
                 Network-layer Traffic Control Mechanisms

     3.3.3 Duplicate Packet

        Definition:
          A received packet with a
          multiple-hop measurement. Test Sequence number matching a
          previously received packet.

        Discussion:

        Measurement units:
          N-octet packets per second

        Issues:
          Packet count

        See Also:
          Intended Vector
          Offered Vector
          Expected Vectors
          Loss Vector
          Stream
          Test Sequence Vector
          Delay Vector
          Jitter Vector

     3.2.4.2 Loss Vector number

     3.3.4 Stream

        Definition:
          The percentage
          A group of packets containing specific DSCP or IP
          precedence value that tracked as a DUT/SUT did not transmit to single entity by the
          correct destination interface in response traffic
          receiver.  A stream may share a common content such as type
          (IP, UDP), packet size, or payload.

        Discussion:
          Streams are tracked by test sequence number or "unique
          signature field" (RFC 2889).  Streams define how individual
          packet's statistics are grouped together to form an offered
          vector.

        Discussion:
          Loss Vector is expressed
          intelligible summary.

          Common stream groupings would be by egress interface,
          destination address, source address, DSCP, or IP precedence.
          A stream using test sequence numbers can track the ordering
          of packets as they transverse the DUT/SUT.

          Streams are not restricted to a pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND the percentage
          value combine to make source and
          destination interfaces as long as all packets are tracked as
          a vector. single entity.  A mulitcast stream can be forward to
          multiple destination interfaces.

        Measurement units:
           n/a

        See Also:
          Flow
          MicroFlow [3]
          Test sequence number
                 Network-layer Traffic Control Mechanisms

          The Loss Vector represents percentage based on a specific
          DSCP or

     3.3.6 Test Sequence number

        Definition:
          A field in the IP precedence value.  It is not necessarily based on
          a stream or flow.  The Loss Vector may be expressed as per
          port payload portion of the DUT/SUT. However, it must be consistent with the
          Expected Loss Vector

          Loss Vector packet that is a per-hop measurement.  The DUT/SUT may change used
          to verify the specific DSCP or IP precedence value for a multiple-hop
          measurement.

        Measurement Units:
          Percentage of offered packets that are not forwarded.

        Issues:

        See Also:
          Intended Vector
          Offered Vector
          Expected Vectors
          Forwarding Vector
          Sequence Vector
          Delay Vector
          Jitter Vector

     3.2.4.3 Sequence Vector

        Definition:
          The number order of the packets per second for all packets containing a
          specific DSCP or IP precedence value that a device can be
          observed to transmit out on the egress of sequence to the correct
          destination interface in response to an offered vector.
          DUT/SUT.

        Discussion:
          Sequence Vector is expressed as pair of numbers.  Both
          The traffic generator sets the
          specific DSCP (or IP precedence) test sequence number value AND and
          the traffic receiver checks the packets per
          second value combine to make a vector. upon receipt of the
          packet.  The Sequence Vector represents traffic generator changes the value on each
          packet rate transmitted based on its
          specific DSCP or IP precedence value.  It is not necessarily
          based an algorithm agreed to by the
          traffic receiver.

          The traffic receiver keeps track of the sequence numbers on a stream or flow.  The Sequence Vector may be
          expressed as
          per port stream basis.  In addition to number of received packets,
          the DUT/SUT.  However, it must be
          consistent with the Expected Sequence Vector.

          Sequence Vector is a per-hop measurement.  The DUT/SUT traffic receiver may also report number of in-sequence
          packets, number of out-sequence packets, number of duplicate
          packets, and number of reordered packets.

          The recommended algorithm to use to change the sequence
          number on sequential packets is an incrementing value.

        Measurement units:
           n/a

        See Also:
          Stream

     3.4 Vectors
          A vector is a group of packets all containing a specific DSCP
          or IP precedence value for value.  Vectors are expressed as a
          multiple-hop measurement.

        Measurement Units:
          N-octet packets per pair of
          numbers.  The first is being the particular diff-serv value.
          The second

        Issues: is the metric expressed as a rate, loss
          percentage, delay, or jitter.

     3.4.1 Intended Vector

        Definition:

          A vector describing the rate at which packets having a
          specific code-point (or IP precedence) that an external
          source attempts to transmit to a DUT/SUT.

        Discussion:
          Intended loads across the different code-point classes
          determine the metrics associated with a specific code-point
          traffic class.

                 Network-layer Traffic Control Mechanisms

        Measurement Units:
          N-octets packets per second

        See Also:
          Intended Vector
          Offered Vector
          Expected Vectors Forwarding Vector
          Expected Loss Vector
          Forwarding
          Expected Sequence Vector
          Expected Delay Vector
          Expected Jitter Vector

     3.2.4.4 Delay
          Forwarding Vector
          Loss Vector

     3.4.2 Offered Vector

        Definition:
          The delay for
          A vector describing the measured rate at which packets containing having
          a specific DSCP or IP precedence value that a device can be observed to
          successfully transmit are offered to the correct destination interface in
          response to an offered vector.
          DUT/SUT.

        Discussion:
          Delay vector is expressed as pair of numbers.  Both
          Offered loads across the
          specific DSCP (or IP precedence) value AND delay value
          combine to make a vector.

          The Delay Vector represents delay on its specific DSCP or IP
          precedence value.  It is not necessarily based on different code-point classes,
          constituting a stream or
          flow.  The Delay vector may be expressed as per port of code-point set, determine the
          DUT/SUT.  However, it must be consistent metrics
          associated with the a specific code-point traffic class.

        Measurement Units:
          N-octets packets per second

        See Also:
          Expected Forwarding Vector
          Expected Loss Vector
          Expected Sequence Vector
          Expected Delay vector.

          Delay Vector
          Expected Jitter Vector
          Forwarding Vector
          Codepoint Set

     3.4.3 Expected Vectors

     3.4.3.1 Expected Forwarding Vector

        Definition:
          A vector is measured similarly regardless of describing the type of
          DUT/SUT.  Latency [1] require some knowledge expected output rate of whether the
          DUT/SUT is a "store and forward" or a "bit forwarding"
          device.  The fact that a DUT/SUT's technology has a lower
          delay than another technology should be visible.

          Delay Vector is packets
          having a per-hop measurement.  The DUT/SUT may
          change the specific DSCP or IP precedence value.  The value for a
          multiple-hop measurement.

          Delay vector can be obtained at any offered load.  Recommend
          at or below the channel capacity in is
          dependent on the absence set of
          congestion.  For congested delay, run the offered load above vectors and configuration of
          the channel capacity.

        Measurement Units:
          seconds

        Issues:

        See Also:
          Delay DUT.

        Discussion:

                 Network-layer Traffic Control Mechanisms

          Intended Vector
          Offered Vector
          Expected Delay Vector
          Loss Vector
          Forwarding Vector
          Jitter Vector

     3.2.4.5 Jitter Vector

        Definition:

          The variation DUT is configured in the delay a certain way in order that service
          differentiation occurs for packets containing specific a particular DSCP or IP precedence
          value that when a device can be observed to
          successfully transmit to the correct destination interface in
          response to an offered vector.

        Discussion:
          Jitter is the absolute value of the difference between the
          delay measurement specific traffic mix consisting of two packets belonging multiple
          DSCPs or IP precedence values are applied. This term attempts
          to capture the same
          stream.

          Jitter vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND jitter value
          combine expected forwarding behavior when subjected to make
          a vector. certain offered vectors.

          The jitter between two consecutive packets in a stream is
          reported as the "instantaneous jitter". Instantaneous jitter
          can be expressed as |D(i) - D(i-1)| where D equals actual algorithm or mechanism the delay
          and i DUT uses to achieve
          service differentiation is the test sequence number.  Packets lost are not
          counted important in describing the jitter measurement.

          Jitter vector is a per-hop measurement.  The DUT/SUT may
          change the specific DSCP or IP precedence value for a
          multiple-hop measurement.

          Average Jitter is the average of the instantaneous jitter
          measured during the test duration.

          Peak-to-peak Jitter is the maximum delay minus the minimum
          delay of the packets forwarded by the DUT/SUT.
          expected forwarding vector.

        Measurement units:
          Seconds (instantaneous)
          Seconds P-P (peak to peak)
          Seconds Avg (average)

        Issues:
          N-octet packets per second

        See Also:
          Intended Vector
          Offered Vector
          Expected
          Output Vectors
                 Network-layer Traffic Control Mechanisms
          Expected Loss Vector
          Expected Sequence Vector
          Expected Delay Vector
          Forwarding
          Expected Jitter Vector

     3.4.3.2 Expected Loss Vector

     3.3 Measurement Terms

     3.3.1 Channel Capacity

        Definition:
          The maximum forwarding rate [2] at which none
          A vector describing the percentage of packets, having a
          specific DSCP or IP precedence value, that should not be
          forwarded.  The value is dependent on the set of offered
          packets are dropped by
          vectors and configuration of the DUT/SUT. DUT.

        Discussion:
          Channel capacity measures the packet rate at the egress
          interface(s) of the DUT/SUT. In contrast, throughput as
          defined in RFC 1242 measures the packet rate is based on the
          ingress interface(s) of the DUT/SUT.

          Ingress-based measurements do not account for congestion of
          the DUT/SUT. Channel capacity, as an egress measurement, does
          take congestion into account.

          Understanding channel capacity
          The DUT is configured in a necessary precursor to
          any measurement involving congestion.  Throughput numbers can
          be higher than channel capacity because of queueing.

          This measurement differs from forwarding rate at maximum
          offered load (FRMOL) [2] certain way in order that it is intolerant of loss.

        Measurement units:

           N-octet packets per second

        Issues:

        See Also:
          Throughput [1]
          Forwarding Rate at Maximum Offered Load [2]

     3.3.2 Conforming

        Definition:
          Packets which lie within specific rate, delay, service
          differentiation occurs for a particular DSCP or jitter
          bounds.

        Discussion:
          A DUT/SUT may be configured to allow IP precedence
          value when a given specific traffic class to
          consume a given amount mix consisting of bandwidth, multiple
          DSCPs or IP precedence values are applied. This term attempts
          to fall within
                 Network-layer Traffic Control Mechanisms

          predefined delay capture the expected forwarding behavior when subjected to
          a certain offered vectors.

          The actual algorithm or jitter boundaries. All mechanism the DUT uses to achieve
          service differentiation is not important in describing the
          expected loss vector.

        Measurement Units:
          Percentage of intended packets that lie
          within specified bounds are then said expected to be conforming,
          whereas those outside the bounds are nonconforming.

        Measurement units:

           n/a

        Issues:
          dropped.

        See Also:
          Expected
          Intended Vector
          Offered Vector
          Expected Forwarding Vector
          Offered
                 Network-layer Traffic Control Mechanisms

          Expected Sequence Vector
          Nonconforming

     3.3.3 Nonconforming

        Definition:
          Packets that do not lie within
          Expected Delay Vector
          Expected Jitter Vector

     3.2.3.3 Expected Sequence Vector

        Definition:
          A vector describing the expected in-sequence packets having a
          specific rate, delay, DSCP or
          jitter bounds. IP precedence value. The value is dependent
          on the set of offered vectors and configuration of the DUT.

        Discussion:
          A DUT/SUT may be
          The DUT is configured to allow in a given traffic class to
          consume certain way in order that service
          differentiation occurs for a given amount particular DSCP or IP precedence
          value when a specific traffic mix consisting of bandwidth, multiple
          DSCPs or IP precedence values are applied. This term attempts
          to fall within
          predefined delay capture the expected forwarding behavior when subjected to
          a certain offered vectors.

          The actual algorithm or jitter boundaries. All packets that do
          not lie within these bounds are then said mechanism the DUT uses to be
          nonconforming. achieve
          service differentiation is not important in describing the
          expected sequence vector.

        Measurement units:

           n/a

        Issues: Units:
          N-octet packets per second

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Forwarding Vector
          Offered
          Expected Delay Vector
          Conforming

     3.3.4
          Expected Jitter Vector

     3.4.3.4 Expected Instantaneous Delay Vector

        Definition:
          The time interval starting when the last bit of
          A vector describing the input IP expected delay for packets reaches the input port of the DUT/SUT and ending when
          the last bit of the output having a
          specific DSCP or IP packets precedence value. The value is seen dependent
          on the output
          port of the DUT/SUT.

        Discussion:

                 Network-layer Traffic Control Mechanisms

          Delay is measured the same regardless of the type set of DUT/SUT.
          Latency [1] require some knowledge offered vectors and configuration of whether the DUT/SUT DUT.

        Discussion:
          The DUT is configured in a "store and forward" or a "bit forwarding" device.  The fact certain way in order that service
          differentiation occurs for a DUT/SUT's technology has particular DSCP or IP precedence
          value when a lower delay than another
          technology should be visible.

          By specifying the metric to be inside the Internet protocol,
          the tester is relieved from specifying the start/end for
          every data link layer protocol that specific traffic mix consisting of multiple
          DSCPs or IP runs on.  This avoids
          determining if the start/end delimiter precedence values are included in applied. This term attempts
          to capture the
          frame.  Also heterogeneous data link protocol can be used in expected forwarding behavior when subjected to
          a test. certain offered vectors.

                 Network-layer Traffic Control Mechanisms

          The measurement point at the end is closely simulates the way
          an internet datagram is processed.  An internet datagram is
          not passed up actual algorithm or down mechanism the stack unless it DUT uses to achieve
          service differentiation is complete.
          Completion occurs once the last bit of the IP packet has been
          received.

          Delay can be run at any offered load.  Recommend at or below
          the channel capacity for non-congested delay.  For congested
          delay, run the offered load above not important in describing the channel capacity.
          expected delay vector.

        Measurement units:
          Seconds.

        Issues:

        See Also:
          Latency [1]

     3.3.5 Flow
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Forwarding Vector
          Expected Jitter Vector

     3.4.3.5 Expected Average Delay Vector

        Definition:
          A flow is a one or more of vector describing the expected average delay for packets sharing
          having a common intended
          pair specific DSCP or IP precedence value. The value is
          dependent on the set of source and destination interfaces.

        Discussion:
          Packets are grouped by the ingress and egress interfaces they
          use on a given DUT/SUT.

          A flow can contain multiple source IP addresses and/or
          destination IP addresses.  All packets in a flow must enter
          on the same ingress interface and exit on the same egress
          interface, offered vectors and have some common network layer content.

          Microflows [3] are a subset configuration of flows.  As defined in [3],
          microflows require application-to-application measurement. In
          contrast, flows use lower-layer classification criteria.
          Since this document focuses on network-layer classification
                 Network-layer Traffic Control Mechanisms

          criteria, we concentrate here on
          the use of network-layer
          identifiers DUT.

        Discussion:
          The DUT is configured in describing a flow. Flow identifiers also may
          reside at the data-link, transport, or application layers of
          the ISO model. However, identifiers other than those at the
          network layer are out of scope certain way in order that service
          differentiation occurs for this document.

          A flow may contain a single code point/IP particular DSCP or IP precedence
          value or
          may contain when a specific traffic mix consisting of multiple
          DSCPs or IP precedence values destined for a single egress
          interface. are applied. This term attempts
          to capture the expected forwarding behavior when subjected to
          a certain offered vectors.

          The actual algorithm or mechanism the DUT uses to achieve
          service differentiation is determined by not important in describing the test methodology.
          expected average delay vector.

        Measurement units:

           n/a

        Issues:
          Seconds.

        See Also:
          Microflow [3]
          Streams

     3.3.6 Stream
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Forwarding Vector
          Expected Jitter Vector
                 Network-layer Traffic Control Mechanisms

     3.4.3.6 Expected Maximum Delay Vector

        Definition:
          A group of packets tracked as vector describing the expected maximum delay for packets
          having a specific DSCP or IP precedence value. The value is
          dependent on the set of offered vectors and configuration of
          the DUT.

        Discussion:
          The DUT is configured in a certain way in order that service
          differentiation occurs for a particular DSCP or IP precedence
          value when a specific traffic mix consisting of multiple
          DSCPs or IP precedence values are applied. This term attempts
          to capture the expected forwarding behavior when subjected to
          a certain offered vectors.

          The actual algorithm or mechanism the DUT uses to achieve
          service differentiation is not important in describing the
          expected maximum delay vector.

        Measurement units:
          Seconds.

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Forwarding Vector
          Expected Jitter Vector

     3.4.3.7 Expected Minimum Delay Vector

        Definition:
          A vector describing the expected minimum delay for packets
          having a specific DSCP or IP precedence value. The value is
          dependent on the set of offered vectors and configuration of
          the DUT.

        Discussion:
          The DUT is configured in a certain way in order that service
          differentiation occurs for a particular DSCP or IP precedence
          value when a specific traffic mix consisting of multiple
          DSCPs or IP precedence values are applied. This term attempts
          to capture the expected forwarding behavior when subjected to
          a certain offered vectors.

          The actual algorithm or mechanism the DUT uses to achieve
          service differentiation is not important in describing the
          expected minimum delay vector.

                 Network-layer Traffic Control Mechanisms

        Measurement units:
          Seconds.

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Loss Vector
          Expected Sequence Vector
          Expected Forwarding Vector
          Expected Jitter Vector

     3.2.3.8 Expected Instantaneous Delay Variation Vector

        Definition:
          A vector describing the expected variation in the delay of
          two consecutive packets' arrival times having a specific DSCP
          or IP precedence value. The value is dependent on the set of
          offered vectors and configuration of the DUT.

        Discussion:
          Instantaneous Delay Variation is the absolute value of the
          difference between the delay measurement of two packets
          belonging to the same stream.

          The delay fluctuation between two consecutive packets in a
          stream is reported as the "Instantaneous Delay Variation".
          Instantaneous Delay Variation can be expressed as |D(i) -
          D(i-1)| where D equals the delay and i is the test sequence
          number.  Packets lost are not counted in the measurement.

          Forwarding Vector may contain several Instantaneous Delay
          Variation Vectors.  For n packets received in a Forwarding
          Vector, there is n-1 several Instantaneous Delay Variation
          Vectors.

        Measurement units:
          Seconds

        See Also:
          Delay
          Offered Vector
          Output Vectors
          Expected Average Delay Variation Vector
          Expected Peak-to-peak Delay Variation Vector
          Stream
                 Network-layer Traffic Control Mechanisms

     3.2.3.9 Expected Average Delay Variation Vector

        Definition:
          A vector describing the expected average variation in the
          delay of packet arrival times for packets having specific
          DSCP or IP precedence value. The value is dependent on the
          set of offered vectors and configuration of the DUT.

        Discussion:
          Average Delay Variation is the average of all the
          Instantaneous Delay Variation Vectors measured during the
          test duration.

        Measurement units:
          Seconds

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Instantaneous Delay Variation Vector
          Expected Peak-to-peak Delay Variation Vector

     3.2.3.10 Expected Peak-to-peak Delay Variation Vector

        Definition:
          A vector describing the expected maximum variation in the
          delay of packet arrival times for packets having specific
          DSCP or IP precedence value. The value is dependent on the
          set of offered vectors and configuration of the DUT.

        Discussion:
          Peak-to-peak Delay Variation Vector is the maximum delay
          minus the minimum delay of the packets (in a vector)
          forwarded by the DUT/SUT.

          Peak-to-peak Delay Variation is not derived from the
          Instantaneous Delay Variation Vector. Peak-to-peak Delay
          Variation is based upon all the packets during the test
          duration, not just two consecutive packets.

        Measurement units:
          Seconds

        See Also:
          Intended Vector
          Offered Vector
          Output Vectors
          Expected Instantaneous Delay Variation Vector
          Expected Average Delay Variation Vector
                 Network-layer Traffic Control Mechanisms

     3.4.4 Output Vectors

     3.4.4.1 Forwarding Vector

        Definition:
          The number of packets per second for all packets containing a
          specific DSCP or IP precedence value that a device can be
          observed to successfully forward to the correct destination
          interface in response to an offered vector.

        Discussion:
          Forwarding Vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND the packets per
          second value combine to make a vector.

          The Forwarding Vector represents packet rate based on its
          specific DSCP (or IP precedence) value.  It is not
          necessarily based on a stream or flow.  The Forwarding Vector
          may be expressed as per port of the DUT/SUT. However, it must
          be consistent with the Expected Forwarding Vector.

          Forwarding Vector is a per-hop measurement.  The DUT/SUT may
          change the specific DSCP (or IP precedence) value for a
          multiple-hop measurement.

        Measurement units:
          N-octet packets per second

        See Also:
          Intended Vector
          Offered Vector
          Expected Vectors
          Loss Vector
          Sequence Vector
          Delay Vectors

     3.4.4.2 Loss Vector

        Definition:
          The percentage of packets containing specific DSCP or IP
          precedence value that a DUT/SUT did not transmit to the
          correct destination interface in response to an offered
          vector.

        Discussion:
          Loss Vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND the percentage
          value combine to make a vector.

                 Network-layer Traffic Control Mechanisms

          The Loss Vector represents percentage based on a specific
          DSCP or IP precedence value.  It is not necessarily based on
          a stream or flow.  The Loss Vector may be expressed as per
          port of the DUT/SUT. However, it must be consistent with the
          Expected Loss Vector

          Loss Vector is a per-hop measurement.  The DUT/SUT may change
          the specific DSCP or IP precedence value for a multiple-hop
          measurement.

        Measurement Units:
          Percentage of offered packets that are not forwarded.

        See Also:
          Intended Vector
          Offered Vector
          Expected Vectors
          Forwarding Vector
          Sequence Vector
          Delay Vectors

     3.4.4.3 Sequence Vector

        Definition:
          The number of packets per second for all packets containing a
          specific DSCP or IP precedence value that a device can be
          observed to transmit in sequence to the correct destination
          interface in response to an offered vector.

        Discussion:
          Sequence Vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND the packets per
          second value combine to make a vector.

          The Sequence Vector represents packet rate based on its
          specific DSCP or IP precedence value.  It is not necessarily
          based on a stream or flow.  The Sequence Vector may be
          expressed as per port of the DUT/SUT.  However, it must be
          consistent with the Expected Sequence Vector.

          Sequence Vector is a per-hop measurement.  The DUT/SUT may
          change the specific DSCP or IP precedence value for a
          multiple-hop measurement.

        Measurement Units:
          N-octet packets per second

        Issues:

        See Also:
          In-sequence Packet
                 Network-layer Traffic Control Mechanisms

          Intended Vector
          Offered Vector
          Expected Vectors
          Loss Vector
          Forwarding Vector
          Delay Vectors

     3.4.4.4 Instantaneous Delay Vector

        Definition:
          The delay for a packet containing specific DSCP or IP
          precedence value that a device can be observed to
          successfully transmit to the correct destination interface in
          response to an offered vector.

        Discussion:
          Instantaneous Delay vector is expressed as pair of numbers.
          Both the specific DSCP (or IP precedence) value AND delay
          value combine to make a vector.

          The Instantaneous Delay Vector represents delay on its
          specific DSCP or IP precedence value.  It is not necessarily
          based on a stream or flow.  The Delay vector may be expressed
          as per port of the DUT/SUT.  However, it must be consistent
          with the Expected Delay vectors.

          Instantaneous Delay Vector is a per-hop measurement.  The
          DUT/SUT may change the specific DSCP or IP precedence value
          for a multiple-hop measurement.

          Instantaneous Delay vector can be obtained at any offered
          load.  Recommend at or below the channel capacity in the
          absence of congestion.  For congested delay, run the offered
          load above the channel capacity.

          Forwarding Vector may contain several Instantaneous Delay
          Vectors.  For every packet received in a Forwarding Vector,
          there is a corresponding Instantaneous Delay Vector.

        Measurement Units:
          Seconds

        See Also:
          Delay
          Intended Vector
          Offered Vector
          Expected Delay Vectors
          Average Delay Vector
          Maximum Delay Vector
          Minimum Delay Vector
                 Network-layer Traffic Control Mechanisms

     3.4.4.5 Average Delay Vector

        Definition:
          The average delay for packets containing specific DSCP or IP
          precedence value that a device can be observed to
          successfully transmit to the correct destination interface in
          response to an offered vector.

        Discussion:
          Average Delay vector is expressed as pair of numbers.  Both
          the specific DSCP (or IP precedence) value AND delay value
          combine to make a vector.

          The Delay Vector represents delay on its specific DSCP or IP
          precedence value.  It is not necessarily based on a stream or
          flow.  The Delay vector may be expressed as per port of the
          DUT/SUT.  However, it must be consistent with the Expected
          Delay vector.

          The Average Delay Vector is computed by averaging all the
          Instantaneous Delay Vectors for a given vector.

          Average Delay Vector is a per-hop measurement.  The DUT/SUT
          may change the specific DSCP or IP precedence value for a
          multiple-hop measurement.

          Average Delay vector can be obtained at any offered load.
          Recommend at or below the channel capacity in the absence of
          congestion.  For congested delay, run the offered load above
          the channel capacity.

        Measurement Units:
          Seconds

        See Also:
          Delay
          Intended Vector
          Offered Vector
          Expected Delay Vectors
          Instantaneous Delay Vector
          Maximum Delay Vector
          Minimum Delay Vector

     3.4.4.6 Maximum Delay Vector

        Definition:
          The maximum delay from all packets containing specific DSCP
          or IP precedence value that a device can be observed to
          successfully transmit to the correct destination interface in
          response to an offered vector.

                 Network-layer Traffic Control Mechanisms

        Discussion:
          Maximum Delay vector is expressed as pair of numbers.  Both
          the specific DSCP (or IP precedence) value AND delay value
          combine to make a vector.

          The Maximum Delay Vector represents delay on its specific
          DSCP or IP precedence value.  It is not necessarily based on
          a stream or flow.  The Maximum Delay vector may be expressed
          as per port of the DUT/SUT.  However, it must be consistent
          with the Expected Delay vector.

          Maximum Delay Vector is based upon the maximum Instantaneous
          Delay Vector of all packets in a Forwarding Vector.

          Maximum Delay Vector is a per-hop measurement.  The DUT/SUT
          may change the specific DSCP or IP precedence value for a
          multiple-hop measurement.

        Measurement Units:
          Seconds

        See Also:
          Delay
          Intended Vector
          Offered Vector
          Expected Delay Vectors
          Instantaneous Delay Vector
          Forwarding Vector
          Average Delay Vector
          Minimum Delay Vector

     3.4.4.7 Minimum Delay Vector

        Definition:
          The minimum delay from all packets containing specific DSCP
          or IP precedence value that a device can be observed to
          successfully transmit to the correct destination interface in
          response to an offered vector.

        Discussion:
          Delay vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND delay value
          combine to make a vector.

          The Minimum Delay Vector represents delay on its specific
          DSCP or IP precedence value.  It is not necessarily based on
          a stream or flow.  The Minimum Delay vector may be expressed
          as per port of the DUT/SUT.  However, it must be consistent
          with the Expected Delay vector.

                 Network-layer Traffic Control Mechanisms

          Minimum Delay Vector is based upon the minimum Instantaneous
          Delay Vector of all packets in a Forwarding Vector.

          Minimum Delay Vector is a single entity by the traffic
          receiver.  A stream per-hop measurement.  The DUT/SUT
          may share a common content such as type
          (IP, UDP), packet size, or payload.

        Discussion:
          Streams are tracked by Test sequence number change the specific DSCP or "unique
          signature field" (RFC 2889).  Streams define how individual
          packet's statistics are grouped together to form an
          intelligible summary.

          Common stream groupings would IP precedence value for a
          multiple-hop measurement.

          Minimum Delay vector can be by egress interface,
          destination address, source address, DSCP, obtained at any offered load.
          Recommend at or below the channel capacity in the absence of
          congestion.  For congested delay, run the offered load above
          the channel capacity.

        Measurement Units:
          Seconds

        See Also:
          Delay
          Intended Vector
          Offered Vector
          Expected Delay Vectors
          Instantaneous Delay Vector
          Forwarding Vector
          Average Delay Vector
          Maximum Delay Vector

     3.4.4.8 Instantaneous Delay Variation Vector

        Definition:
          The variation in the delay for two consecutive packets
          containing specific DSCP or IP precedence.
          A stream using Test sequence numbers precedence value that a device
          can track be observed to successfully transmit to the ordering correct
          destination interface in response to an offered vector.

        Discussion:
          Instantaneous Delay Variation is the absolute value of the
          difference between the delay measurement of two packets
          belonging to the same stream.

          Jitter vector is expressed as pair of numbers.  Both the
          specific DSCP (or IP precedence) value AND jitter value
          combine to make a vector.

          The delay fluctuation between two consecutive packets in a
          stream is reported as they transverse the DUT/SUT.

          Streams "Instantaneous Delay Variation".
          Instantaneous Delay Variation can be expressed as |D(i) -
          D(i-1)| where D equals the delay and i is the test sequence
          number.  Packets lost are not restricted to counted in the measurement.

                 Network-layer Traffic Control Mechanisms

          Instantaneous Delay Variation Vector is a pair of source and
          destination interfaces as long as all per-hop
          measurement.  The DUT/SUT may change the specific DSCP or IP
          precedence value for a multiple-hop measurement.

          Forwarding Vector may contain several Instantaneous Delay
          Variation Vectors.  For n packets are tracked as received in a single entity.  A mulitcast stream can be forward to
          multiple destination interfaces. Forwarding
          Vector, there is n-1 several Instantaneous Delay Variation
          Vectors.

        Measurement units:

           n/a

        Issues:

                 Network-layer Traffic Control Mechanisms
          Seconds

        See Also:
          Flow
          MicroFlow [3]
          Test sequence number

     3.3.7 Test Sequence number
          Delay
          Forwarding Vector
          Stream
          Expected Vectors
          Average Delay Variation Vector
          Peak-to-peak Delay Variation Vector

     3.4.4.9 Average Delay Variation Vector

        Definition:
          A field
          The average variation in the delay for packets containing
          specific DSCP or IP payload portion of the packet precedence value that is used a device can be
          observed to successfully transmit to verify the order of the packets on the egress of the
          DUT/SUT.

        Discussion:
          The traffic generator sets the Test sequence number value and
          the traffic receiver checks the value upon receipt of the
          packet.  The traffic generator changes the value on each
          packet transmitted based on an algorithm agreed correct destination
          interface in response to by an offered vector.

        Discussion:
          Average Delay Variation is the
          traffic receiver.

          The traffic receiver keeps track average of all the sequence numbers on a
          per stream basis.  In addition to number of received packets,
          Instantaneous Delay Variation Vectors measured during the traffic receiver may also report number of in-sequence
          packets, number of out-sequence packets, number of duplicate
          packets, and number of reordered packets.

          The recommended algorithm to use
          test duration.

          Average Delay Variation vector is expressed as pair of
          numbers.  Both the specific DSCP (or IP precedence) value AND
          jitter value combine to make a vector.

          Average Delay Variation vector is a per-hop measurement.  The
          DUT/SUT may change the sequence
          number on sequential packets is an incrementing value. specific DSCP or IP precedence value
          for a multiple-hop measurement.

        Measurement units:

           n/a

        Issues:
          Seconds

        See Also:
          Delay
          Forwarding Vector
          Stream

     3.3.8 Undifferentiated Response

        Definition:
          The vector(s) obtained when mechanisms used to support diff-
          serv or IP precedence are disabled.

        Discussion:
          Enabling diff-serv or IP precedence mechanisms may impose
          additional processing overhead for packets. This overhead may
          degrade performance even when traffic belonging to only one
          class, the best-effort class, is offered to the device.
          Expected Vectors
          Instantaneous Delay Variation Vector
          Peak-to-peak Delay Variation Vector
                 Network-layer Traffic Control Mechanisms

          Measurements with "undifferentiated response" should be made
          to establish a baseline.

     3.4.4.10 Peak-to-peak Delay Variation Vector

        Definition:
          The vector(s) obtained with DSCPs maximum possible variation in the delay for packets
          containing specific DSCP or IP precedence enabled value that a device
          can be compared observed to successfully transmit to the undifferentiated correct
          destination interface in response to determine an offered vector.

        Discussion:
          Peak-to-peak Delay Variation Vector is the effect maximum delay
          minus the minimum delay of differentiating traffic. the packets (in a vector)
          forwarded by the DUT/SUT.

          Delay Variation vector is expressed as pair of numbers.  Both
          the specific DSCP (or IP precedence) value AND jitter value
          combine to make a vector.

          Peak-to-peak Delay Variation is not derived from the
          Instantaneous Delay Variation Vector. Peak-to-peak Delay
          Variation is based upon all the packets during the test
          duration, not just two consecutive packets.

        Measurement units:

          n/a
          Seconds

        See Also:
          Delay
          Forwarding Vector
          Stream
          Expected Vectors
          Average Delay Variation Vector
          Peak-to-peak Delay Variation Vector
                 Network-layer Traffic Control Mechanisms

     4. Security Considerations

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

          Packets with unintended and/or unauthorized DSCP or IP
          precedence values may present security issues. Determining
          the security consequences of such packets is out of scope for
          this document.

     5. References

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

        [2]   Mandeville, R., "Benchmarking Terminology for LAN
              Switching Devices", RFC 2285, February 1998.

        [3]   K. Nichols, S. Blake, F. Baker, D. Black,"Definition of
              the Differentiated Services Field (DS Field) in the IPv4
              and IPv6 Headers", RFC 2474, December 1998.

        [4]   S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W.
              Weiss, "An Architecture for Differentiated Services", RFC
              2475, December 1998.

                 Network-layer Traffic Control Mechanisms

     6. Authors' Address

          Jerry Perser
          Spirent Communications
          26750 Agoura Road
          Calabasas, CA 91302
          USA

          Phone: + 1 818 676 2300
          EMail: jerry.perser@spirentcom.com

          David Newman
          Network Test
          31324 Via Colinas, Suite 113
          Westlake Village, CA 91362
          USA

          Phone: + 1 818 889 0011, x10
          EMail: dnewman@networktest.com

          Sumit Khurana
          Telcordia Technologies
          445 South Street
          Morristown, NJ 07960
          USA

          Phone: + 1 973 829 3170
          EMail: sumit@research.telcordia.com

          Shobha Erramilli
          QNetworx Inc
          1119 Campus Drive West
          Morganville NJ 07751
          USA

          Phone:
          EMail: shobha@qnetworx.com

          Scott Poretsky
          Avici Systems
          101 Billerica Ave_Building #6
          N. Billerica, MA 01862
          USA

          Phone: + 1 978 964 2287
          EMail: sporetsky@avici.com
                 Network-layer Traffic Control Mechanisms

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