draft-ietf-bmwg-dsmterm-06.txt   draft-ietf-bmwg-dsmterm-07.txt 
Network Working Group Jerry Perser Network Working Group Jerry Perser
INTERNET-DRAFT Spirent INTERNET-DRAFT Spirent
Expires in: November 2003 David Newman Expires in: December 2003 David Newman
Network Test Network Test
Sumit Khurana Sumit Khurana
Telcordia Telcordia
Shobha Erramilli Shobha Erramilli
QNetworx QNetworx
Scott Poretsky Scott Poretsky
Avici Systems Avici Systems
April 2003 June 2003
Terminology for Benchmarking Network-layer Terminology for Benchmarking Network-layer
Traffic Control Mechanisms Traffic Control Mechanisms
<draft-ietf-bmwg-dsmterm-06.txt> <draft-ietf-bmwg-dsmterm-07.txt>
Status of this Memo Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document describes terminology for the benchmarking of
devices that implement traffic control based on IP precedence or
diff-serv code point criteria.
Network-layer Traffic Control Mechanisms
Table of Contents Table of Contents
1. Introduction .............................................. 3 1. Introduction .............................................. 3
2. Existing definitions ...................................... 3 2. Existing definitions ...................................... 3
3. Term definitions ............................................4 3. Term definitions ............................................4
3.1 Configuration Terms 3.1 Configuration Terms
3.1.1 Classification .........................................4 3.1.1 Classification .........................................4
3.1.2 Codepoint Set ..........................................4 3.1.2 Codepoint Set ..........................................4
3.1.3 Forwarding Congestion ..................................5 3.1.3 Forwarding Congestion ..................................5
3.1.4 Congestion Management ..................................6 3.1.4 Congestion Management ..................................6
3.1.5 Flow ...................................................6 3.1.5 Flow ...................................................7
3.2 Measurement Terms 3.2 Measurement Terms
Network-layer Traffic Control Mechanisms
3.2.1 Channel Capacity .......................................7 3.2.1 Channel Capacity .......................................7
3.2.2 Conforming .............................................8 3.2.2 Conforming Packet ......................................8
3.2.3 Nonconforming ..........................................8 3.2.3 Nonconforming Packet ...................................9
3.2.4 Forwarding Delay .......................................9 3.2.4 Forwarding Delay .......................................9
3.2.5 Jitter ................................................10 3.2.5 Jitter ................................................11
3.2.6 Undifferentiated Response .............................11 3.2.6 Undifferentiated Response .............................11
3.3 Sequence Tracking 3.3 Sequence Tracking
3.3.1 In-sequence Packet ....................................11 3.3.1 In-sequence Packet ....................................12
3.3.2 Out-of-order Packet ...................................12 3.3.2 Out-of-order Packet ...................................12
3.3.3 Duplicate Packet ......................................13 3.3.3 Duplicate Packet ......................................13
3.3.4 Stream ................................................13 3.3.4 Stream ................................................14
3.3.5 Test Sequence number .................................14 3.3.5 Test Sequence number .................................14
3.4 Vectors ...................................................14 3.4 Vectors ...................................................15
3.4.1 Intended Vector .......................................14 3.4.1 Intended Vector .......................................15
3.4.2 Offered Vector ........................................15 3.4.2 Offered Vector ........................................16
3.4.3 Expected Vectors 3.4.3 Expected Vectors
3.4.3.1 Expected Forwarding Vector ........................15 3.4.3.1 Expected Forwarding Vector ........................16
3.4.3.2 Expected Loss Vector ..............................16 3.4.3.2 Expected Loss Vector ..............................17
3.4.3.3 Expected Sequence Vector ..........................17 3.4.3.3 Expected Sequence Vector ..........................18
3.4.3.4 Expected Instantaneous Delay Vector ...............17 3.4.3.4 Expected Instantaneous Delay Vector ...............18
3.4.3.5 Expected Average Delay Vector .....................18 3.4.3.5 Expected Average Delay Vector .....................19
3.4.3.6 Expected Maximum Delay Vector .....................19 3.4.3.6 Expected Maximum Delay Vector .....................10
3.4.3.7 Expected Minimum Delay Vector .....................19 3.4.3.7 Expected Minimum Delay Vector .....................20
3.4.3.8 Expected Instantaneous Jitter Vector ..............20 3.4.3.8 Expected Instantaneous Jitter Vector ..............21
3.4.3.9 Expected Average Jitter Vector ....................21 3.4.3.9 Expected Average Jitter Vector ....................22
3.4.3.10 Expected Peak-to-peak Jitter Vector ..............21 3.4.3.10 Expected Peak-to-peak Jitter Vector ..............22
3.4.4 Output Vectors 3.4.4 Output Vectors
3.4.4.1 Forwarding Vector .................................22 3.4.4.1 Forwarding Vector .................................23
3.4.4.2 Loss Vector .......................................23 3.4.4.2 Loss Vector .......................................24
3.4.4.3 Sequence Vector ...................................23 3.4.4.3 Sequence Vector ...................................24
3.4.4.4 Instantaneous Delay Vector ........................24 3.4.4.4 Instantaneous Delay Vector ........................25
3.4.4.5 Average Delay Vector ..............................25 3.4.4.5 Average Delay Vector ..............................26
3.4.4.6 Maximum Delay Vector ..............................26 3.4.4.6 Maximum Delay Vector ..............................27
3.4.4.7 Minimum Delay Vector ..............................27 3.4.4.7 Minimum Delay Vector ..............................28
3.4.4.8 Instantaneous Jitter Vector .......................27 3.4.4.8 Instantaneous Jitter Vector .......................28
3.4.4.9 Average Jitter Vector .............................28 3.4.4.9 Average Jitter Vector .............................29
3.4.4.10 Peak-to-peak Jitter Vector .......................29 3.4.4.10 Peak-to-peak Jitter Vector .......................30
4. Security Considerations ....................................30 4. Acknowledgments ............................................31
5. Acknowledgments ............................................30 5. Security Considerations ....................................31
6. Normative References .......................................30 6. Normative References .......................................31
7. Informative References .....................................31
8. Author's Address ...........................................32
9. Full Copyright Statement ...................................33
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
1. Introduction 7. Informative References .....................................32
8. Author's Address ...........................................33
9. Full Copyright Statement ...................................34
This document describes terminology for the benchmarking of 1. Introduction
devices that implement traffic control based on IP precedence or
diff-serv code point criteria.
New terminology is needed because most existing measurements New terminology is needed because most existing measurements
assume the absence of congestion and only a single per-hop- assume the absence of congestion and only a single per-hop-
behavior. This document introduces several new terms that will behavior. This document introduces several new terms that will
allow measurements to be taken during periods of congestion. allow measurements to be taken during periods of congestion.
Another key difference from existing terminology is the definition Another key difference from existing terminology is the definition
of measurements as observed on egress as well as ingress of a of measurements as observed on egress as well as ingress of a
device/system under test. Again, the existence of congestion device/system under test. Again, the existence of congestion
requires the addition of egress measurements as well as those requires the addition of egress measurements as well as those
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control mechanisms and should also be consulted. control mechanisms and should also be consulted.
For the sake of clarity and continuity this RFC adopts the For the sake of clarity and continuity this RFC adopts the
template for definitions set out in Section 2 of RFC 1242. template for definitions set out in Section 2 of RFC 1242.
Definitions are indexed and grouped together in sections for ease Definitions are indexed and grouped together in sections for ease
of reference. of reference.
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 in "OPTIONAL" in this document are to be interpreted as described in
RFC 2119. RFC 2119 [Br97].
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
3. Term definitions 3. Term definitions
3.1 Configuration Terms 3.1 Configuration Terms
3.1.1 Classification 3.1.1 Classification
Definition: Definition:
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Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
3.1.3 Forwarding Congestion 3.1.3 Forwarding Congestion
Definition: Definition:
A condition in which one or more egress interfaces are A condition in which one or more egress interfaces are
offered more packets than are forwarded. offered more packets than are forwarded.
Discussion: Discussion:
This condition is a superset of the overload definition This condition is a superset of the overload definition
[Ma98]. The overload discussion deals with how many input [Ma98]. Overload [Ma98] deals with overloading input and
interfaces are required to overload the output interfaces. output interfaces beyond the maximum transmission allowed by
Forwarding congestion does not assume ingress interface the medium. Forwarding congestion does not assume ingress
overload as the only source of overload on output interfaces. interface overload as the only source of overload on output
interfaces.
Another difference between Forwarding Congestion and overload Another difference between Forwarding Congestion and overload
occurs when the SUT comprises multiple elements, in that occurs when the SUT comprises multiple elements, in that
Forwarding Congestion may occur at multiple points. Consider Forwarding Congestion may occur at multiple points. Consider
an SUT comprising multiple edge devices exchanging traffic an SUT comprising multiple edge devices exchanging traffic
with a single core device. Depending on traffic patterns, the with a single core device. Depending on traffic patterns,
edge devices may induce Forwarding Congestion on multiple the edge devices may induce Forwarding Congestion on multiple
egress interfaces on the core device. egress interfaces on the core device.
Packet Loss, not increased Delay, is the metric to indicate Packet Loss, not increased Delay, is the metric to indicate
the condition of Forwarding Congestion. Packet Loss is a the condition of Forwarding Congestion. Packet Loss is a
deterministic indicator of Forwarding Congestion. While deterministic indicator of Forwarding Congestion. While
increased delay may be an indicator of Forwarding Congestion, increased delay may be an indicator of Forwarding Congestion,
it is a non-deterministic indicator of Forwarding Congestion. it is a non-deterministic indicator of Forwarding Congestion.
External observation of increased delay to indicate External observation of increased delay to indicate
congestion is in effect external observation of Incipient congestion is in effect external observation of Incipient
Congestion. [Ra99] states that it is impractical to build a Congestion.
black-box test to externally observe Incipient Congestion in
a router. For the purpose of "black-box" testing a DUT/SUT, [Ra99] implies that it is impractical to build a black-box
Packet Loss as the indicator of Forwarding Congestion is test to externally observe Incipient Congestion indicated by
used. increased delay in a router. [Ra99] introduces Explicit
Congestion Notification (ECN) as the externally observable,
deterministic method for indicating Incipient Congestion.
Because [Ra99] is an Experimental RFC with limited
deployment, ECN is not used for this particular methodology.
For the purpose of "black-box" testing a DUT/SUT, Packet Loss
as the indicator of Forwarding Congestion is used.
Throughput [Br91] defines the lower boundary of Forwarding Throughput [Br91] defines the lower boundary of Forwarding
Congestion. Throughput is the maximum offered rate with no Congestion. Throughput is the maximum offered rate with no
Forwarding Congestion. At offered rates above throughput, the Forwarding Congestion. At offered rates above throughput,
DUT/SUT is considered to be in a state of Forwarding the DUT/SUT is considered to be in a state of Forwarding
Congestion. Congestion.
Ingress observations alone are not sufficient to cover all
cases in which Forwarding 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, Forwarding Congestion is present in this
hypothetical device.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
Ingress observations alone are not sufficient to cover all
cases in which Forwarding Congestion may occur. A device
with an infinite amount of memory could buffer an infinite
number 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, Forwarding Congestion is present in
this hypothetical device.
Forwarding Congestion, indicated by occurrence of packet Forwarding Congestion, indicated by occurrence of packet
loss, is one type of congestion for a DUT/SUT. Congestion loss, is one type of congestion for a DUT/SUT. Congestion
Collapse [Na84] is defined as the state in which buffers are Collapse [Na84] is defined as the state in which buffers are
full and all arriving packets must be dropped across the full and all arriving packets must be dropped across the
network. Incipient Congestion [Ra99] is defined as network. Incipient Congestion [Ra99] is defined as
congestion that produces increased delay without packet loss. congestion that produces increased delay without packet loss.
The definition presented here explicitly defines Forwarding The definition presented here explicitly defines Forwarding
Congestion as an event observable on egress interfaces. Congestion as an event observable on egress interfaces.
Regardless of internal architecture, any device that cannot Regardless of internal architecture, any device that cannot
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Congestion control mechanisms gives one or flows (with a Congestion control mechanisms gives one or flows (with a
discrete IP Precedence or DSCP value) preferential treatment discrete IP Precedence or DSCP value) preferential treatment
over other classes during periods of congestion. over other classes during periods of congestion.
Measurement units: Measurement units:
n/a n/a
See Also: See Also:
Network-layer Traffic Control Mechanisms
3.1.5 Flow 3.1.5 Flow
Definition: Definition:
A flow is a one or more of packets sharing a common intended A flow is a one or more of packets sharing a common intended
pair of source and destination interfaces. pair of source and destination interfaces.
Discussion: Discussion:
Network-layer Traffic Control Mechanisms
Packets are grouped by the ingress and egress interfaces they Packets are grouped by the ingress and egress interfaces they
use on a given DUT/SUT. use on a given DUT/SUT.
A flow can contain multiple source IP addresses and/or A flow can contain multiple source IP addresses and/or
destination IP addresses. All packets in a flow must enter destination IP addresses. All packets in a flow must enter
on the same ingress interface and exit on the same egress on the same ingress interface and exit on the same egress
interface, and have some common network layer content. interface, and have some common network layer content.
Microflows [Ni98] are a subset of flows. As defined in Microflows [Ni98] are a subset of flows. As defined in
[Ni98], microflows require application-to-application [Ni98], microflows require application-to-application
measurement. In contrast, flows use lower-layer measurement. In contrast, flows use lower-layer
classification criteria. Since this document focuses on classification criteria. Since this document focuses on
network-layer classification criteria, we concentrate here on network-layer classification criteria, we concentrate here on
the use of network-layer identifiers in describing a flow. the use of network-layer identifiers in describing a flow.
Flow identifiers also may reside at the data-link, transport, Flow identifiers also may reside at the data-link, transport,
or application layers of the ISO model. However, identifiers or application layers of the OSI model. However, identifiers
other than those at the network layer are out of scope for other than those at the network layer are out of scope for
this document. this document.
A flow may contain a single code point/IP precedence value or A flow may contain a single code point/IP precedence value or
may contain multiple values destined for a single egress may contain multiple values destined for a single egress
interface. This is determined by the test methodology. interface. This is determined by the test methodology.
Measurement units: Measurement units:
n/a n/a
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Streams Streams
3.2 Measurement Terms 3.2 Measurement Terms
3.2.1 Channel Capacity 3.2.1 Channel Capacity
Definition: Definition:
The maximum forwarding rate [Ma98] at which none of the The maximum forwarding rate [Ma98] at which none of the
offered packets are dropped by the DUT/SUT. offered packets are dropped by the DUT/SUT.
Network-layer Traffic Control Mechanisms
Discussion: Discussion:
Channel capacity measures the packet rate at the egress Channel capacity measures the packet rate at the egress
interface(s) of the DUT/SUT. In contrast, throughput as interface(s) of the DUT/SUT. In contrast, throughput as
defined in RFC 1242 measures the packet rate at the ingress defined in RFC 1242 measures the packet rate at the ingress
interface(s) of the DUT/SUT. interface(s) of the DUT/SUT.
Ingress-based measurements do not account for congestion of Ingress-based measurements do not account for congestion of
the DUT/SUT. Channel capacity, as an egress measurement, does the DUT/SUT. Channel capacity, as an egress measurement,
take congestion into account. does take congestion into account.
Network-layer Traffic Control Mechanisms
Understanding channel capacity is a necessary precursor to Understanding channel capacity is a necessary precursor to
any measurement involving congestion. Throughput numbers can any measurement involving forwarding congestion. Throughput
be higher than channel capacity because of queueing. numbers can be higher than channel capacity because of
queuing.
This measurement differs from forwarding rate at maximum This measurement differs from forwarding rate at maximum
offered load (FRMOL) [Ma98] in that it is intolerant of loss. offered load (FRMOL) [Ma98] in that it is intolerant of loss.
Measurement units: Measurement units:
N-octet packets per second N-octet packets per second
See Also: See Also:
Throughput [Br91] Throughput [Br91]
Forwarding Rate at Maximum Offered Load [Ma98] Forwarding Rate at Maximum Offered Load [Ma98]
3.2.2 Conforming 3.2.2 Conforming Packet
Definition: Definition:
Packets which lie within specific rate, delay, or jitter Packets which lie within specific rate, delay, or jitter
bounds. bounds.
Discussion: Discussion:
A DUT/SUT may be configured to allow a given traffic class to A DUT/SUT may be configured to allow a given traffic class to
consume a given amount of bandwidth, or to fall within consume a given amount of bandwidth, or to fall within
predefined delay or jitter boundaries. All packets that lie predefined delay or jitter boundaries. All packets that lie
within specified bounds are then said to be conforming, within specified bounds are then said to be conforming,
whereas those outside the bounds are nonconforming. whereas those outside the bounds are nonconforming.
Measurement units: Measurement units:
n/a n/a
See Also: See Also:
Expected Vector Expected Vector
Forwarding Vector Forwarding Vector
Offered Vector Offered Vector
Nonconforming Nonconforming
Network-layer Traffic Control Mechanisms
3.2.3 Nonconforming 3.2.3 Nonconforming Packet
Definition: Definition:
Packets that do not lie within specific rate, delay, or Packets that do not lie within specific rate, delay, or
jitter bounds. jitter bounds.
Discussion: Discussion:
A DUT/SUT may be configured to allow a given traffic class to A DUT/SUT may be configured to allow a given traffic class to
consume a given amount of bandwidth, or to fall within consume a given amount of bandwidth, or to fall within
predefined delay or jitter boundaries. All packets that do predefined delay or jitter boundaries. All packets that do
not lie within these bounds are then said to be not lie within these bounds are then said to be
nonconforming. nonconforming.
Network-layer Traffic Control Mechanisms
Measurement units: Measurement units:
n/a n/a
See Also: See Also:
Expected Vector Expected Vector
Forwarding Vector Forwarding Vector
Offered Vector Offered Vector
Conforming Conforming
3.2.4 Forwarding Delay 3.2.4 Forwarding Delay
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1. Latency [Br91] assumes knowledge of whether the DUT/SUT 1. Latency [Br91] assumes knowledge of whether the DUT/SUT
uses "store and forward" or "bit forwarding" technology. uses "store and forward" or "bit forwarding" technology.
Forwarding Delay is the same metric, measured the same way, Forwarding Delay is the same metric, measured the same way,
regardless of the architecture of the DUT/SUT. regardless of the architecture of the DUT/SUT.
2. Forwarding Delay is a last-in, last-out (LILO) 2. Forwarding Delay is a last-in, last-out (LILO)
measurement, unlike the last-in, first-out method [Br91] or measurement, unlike the last-in, first-out method [Br91] or
the first-in, last-out method [Al99]. the first-in, last-out method [Al99].
Network-layer Traffic Control Mechanisms
The LILO method most closely simulates the way a network- The LILO method most closely simulates the way a network-
layer device actually processes an IP datagram. IP datagrams layer device actually processes an IP datagram. IP datagrams
are not passed up and down the stack unless they are are not passed up and down the stack unless they are
complete, and processing begins only once the last bit of the complete, and processing begins only once the last bit of the
IP datagram has been received. IP datagram has been received.
Further, the LILO method has an additive property, where the Further, the LILO method has an additive property, where the
sum of the parts MUST equal the whole. This is a key sum of the parts MUST equal the whole. This is a key
difference from [Br91] and [Al99]. For example, the delay difference from [Br91] and [Al99]. For example, the delay
added by two DUTs MUST equal the sum of the delay of the added by two DUTs MUST equal the sum of the delay of the
DUTs. This may or may not be the case with [Br91] and [Al99]. DUTs. This may or may not be the case with [Br91] and
[Al99].
3. Forwarding Delay measures the IP datagram only, unlike 3. Forwarding Delay measures the IP datagram only, unlike
[Br91], which also includes link layer overhead. [Br91], which also includes link layer overhead.
Network-layer Traffic Control Mechanisms
A metric focused exclusively on the Internet protocol A metric focused exclusively on the Internet protocol
relieves the tester from specifying the start/end for every relieves the tester from specifying the start/end for every
link layer protocol that IP runs on. This avoids the need to link layer protocol that IP runs on. This avoids the need to
determine whether the start/stop delimiters are included. It determine whether the start/stop delimiters are included. It
also allows the use of heterogeneous link layer protocols in also allows the use of heterogeneous link layer protocols in
a test. a test.
4. Forwarding Delay can be measured at any offered load, 4. Forwarding Delay can be measured at any offered load,
whereas the latency methodology [Br99] recommends measurement whereas the latency methodology [Br99] recommends measurement
at, and only at, the throughput level. Comparing the at, and only at, the throughput level. Comparing the
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Delay can be said to indicate the presence or absence of Delay can be said to indicate the presence or absence of
Forwarding Congestion. Forwarding Congestion.
Measurement units: Measurement units:
Seconds. Seconds.
See Also: See Also:
Latency [Br91] Latency [Br91]
Latency [Al99] Latency [Al99]
One-way Delay [Br99] One-way Delay [Br99]
Network-layer Traffic Control Mechanisms
3.2.5 Jitter 3.2.5 Jitter
Definition: Definition:
The absolute value of the difference between the arrival The absolute value of the difference between the arrival
delay of two consecutive received packets belonging to the delay of two consecutive received packets belonging to the
same stream. same stream.
Discussion: Discussion:
The delay fluctuation between two consecutive received The delay fluctuation between two consecutive received
packets in a stream is reported as the jitter. Jitter can be packets in a stream is reported as the jitter. Jitter can be
expressed as |D(i) - D(i-1)| where D equals the delay and i expressed as |D(i) - D(i-1)| where D equals the delay and i
is the order the packets were received. is the order the packets were received.
Under loss, jitter can be measured between non-consecutive Under loss, jitter can be measured between non-consecutive
test sequence numbers. When Traffic Control Mechanisms are test sequence numbers. When Traffic Control Mechanisms are
losing packets, the Forwarding Delay may fluctuate as a losing packets, the Forwarding Delay may fluctuate as a
Network-layer Traffic Control Mechanisms
response. Jitter MUST be able to benchmark the delay response. Jitter MUST be able to benchmark the delay
variation with or with out loss. variation with or with out loss.
Jitter is related to the ipdv [De02] (IP Delay Variation) by Jitter is related to the ipdv [De02] (IP Delay Variation) by
taking the absolute value of the ipdv. The two metrics will taking the absolute value of the ipdv. The two metrics will
produce different mean values. _Mean Jitter_ will produce a produce different mean values. _Mean Jitter_ will produce a
positive value, where the _mean ipdv_ is typically zero. positive value, where the _mean ipdv_ is typically zero.
Measurement units: Measurement units:
Seconds Seconds
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interarrival jitter [Sc96] interarrival jitter [Sc96]
3.2.6 Undifferentiated Response 3.2.6 Undifferentiated Response
Definition: Definition:
The vector(s) obtained when mechanisms used to support diff- The vector(s) obtained when mechanisms used to support diff-
serv or IP precedence are disabled. serv or IP precedence are disabled.
Discussion: Discussion:
Enabling diff-serv or IP precedence mechanisms may impose Enabling diff-serv or IP precedence mechanisms may impose
additional processing overhead for packets. This overhead may additional processing overhead for packets. This overhead
degrade performance even when traffic belonging to only one may degrade performance even when traffic belonging to only
class, the best-effort class, is offered to the device. one class, the best-effort class, is offered to the device.
Measurements with "undifferentiated response" should be made Measurements with "undifferentiated response" should be made
to establish a baseline. to establish a baseline.
The vector(s) obtained with DSCPs or IP precedence enabled The vector(s) obtained with DSCP or IP precedence enabled can
can be compared to the undifferentiated response to determine be compared to the undifferentiated response to determine the
the effect of differentiating traffic. effect of differentiating traffic.
Network-layer Traffic Control Mechanisms
Measurement units: Measurement units:
n/a n/a
3.3 Sequence Tracking 3.3 Sequence Tracking
3.3.1 In-sequence Packet 3.3.1 In-sequence Packet
Definition: Definition:
A received packet with the expected Test Sequence number. A received packet with the expected Test Sequence number.
Discussion: Discussion:
In-sequence is done on a stream level. As packets are In-sequence is done on a stream level. As packets are
received on a stream, each packet's Test Sequence number is received on a stream, each packet's Test Sequence number is
Network-layer Traffic Control Mechanisms
compared with the previous packet. Only packets that match compared with the previous packet. Only packets that match
the expected Test Sequence number are considered in-sequence. the expected Test Sequence number are considered in-sequence.
Packets that do not match the expected Test Sequence number Packets that do not match the expected Test Sequence number
are counted as _not in-sequence_ or out-of-sequence. Every are counted as "not in-sequence" or out-of-sequence. Every
packet that is received is either in-sequence or out-of- packet that is received is either in-sequence or out-of-
sequence. Subtracting the in-sequence from the received sequence. Subtracting the in-sequence from the received
packets (for that stream) can derive the out-of-sequence packets (for that stream) can derive the out-of-sequence
count. count.
Two types of events will prevent the in-sequence from Two types of events will prevent the in-sequence from
incrementing: packet loss and reordered packets. incrementing: packet loss and reordered packets.
Measurement units: Measurement units:
Packet count Packet count
See Also: See Also:
Stream Stream
Test Sequence number Test Sequence number
3.3.2 Out-of-order Packet 3.3.2 Out-of-order Packet
Definition: Definition:
A received packet with a Test Sequence number less that A received packet with a Test Sequence number less than
expected. expected.
Discussion: Discussion:
As a stream of packets enter a DUT/SUT, they include a Stream As a stream of packets enters a DUT/SUT, they include a
Test Sequence number indicating the order the packets were Stream Test Sequence number indicating the order the packets
sent to the DUT/SUT. On exiting the DUT/SUT, these packets were sent to the DUT/SUT. On exiting the DUT/SUT, these
may arrive in a different order. Each packet that was re- packets may arrive in a different order. Each packet that
ordered is counted as an Out-of-order Packet. was re-ordered is counted as an Out-of-order Packet.
Network-layer Traffic Control Mechanisms
Certain streaming protocol (such as TCP) require the packets Certain streaming protocol (such as TCP) require the packets
to be in a certain order. Packets outside this are dropped to be in a certain order. Packets outside this are dropped
by the streaming protocols even though there were properly by the streaming protocols even though there were properly
received by the IP layer. The type of reordering tolerated received by the IP layer. The type of reordering tolerated
by a streaming protocol varies from protocol to protocol, and by a streaming protocol varies from protocol to protocol, and
also by implementation. also by implementation.
Out-of-order Packet count is based on the worst case Out-of-order Packet count is based on the worst case
streaming protocol. It allows for no reordering. streaming protocol. It allows for no reordering.
Packet loss does not affect the Out-of-order Packet count. Packet loss does not affect the Out-of-order Packet count.
Only packets that were not received in the order that they Only packets that were not received in the order that they
were transmitted. were transmitted.
Measurement units: Measurement units:
Packet count Packet count
See Also: See Also:
Network-layer Traffic Control Mechanisms
Stream Stream
Test Sequence number Test Sequence number
Packet Reordering Metric for IPPM [Mo03]
3.3.3 Duplicate Packet 3.3.3 Duplicate Packet
Definition: Definition:
A received packet with a Test Sequence number matching a A received packet with a Test Sequence number matching a
previously received packet. previously received packet.
Discussion: Discussion:
A Duplicate Packet is a packet that the DUT/SUT has
successfully transmitted out an egress interface more than
once. The egress interface has previously forwarded this
packet.
A Duplicate Packet SHOULD be a bit for bit copy of an already
transmitted packet (including Test Sequence number). If the
Duplicate Packet traversed different paths through the
DUT/SUT, some fields (such as TTL or checksum) may have
changed.
A multicast packet is not a Duplicate Packet by definition.
For a given IP multicast group, a DUT/SUT SHOULD forward a
packet once on a given egress interface provided the path to
one or more multicast receivers is through that interface.
Several egress interfaces will transmit the same packet, but
only once per interface.
To detect a Duplicate Packet, each offered packet to the
DUT/SUT MUST contain a unique packet-by-packet identifier.
Network-layer Traffic Control Mechanisms
Measurement units: Measurement units:
Packet count Packet count
See Also: See Also:
Stream Stream
Test Sequence number Test Sequence number
3.3.4 Stream 3.3.4 Stream
Definition: Definition:
A group of packets tracked as a single entity by the traffic A group of packets tracked as a single entity by the traffic
receiver. A stream may share a common content such as type receiver. A stream may share a common content such as type
(IP, UDP), packet size, or payload. (IP, UDP), packet size, or payload.
Discussion: Discussion:
Streams are tracked by test sequence number or "unique Streams are tracked by test sequence number or "unique
signature field" [Ma00]. Streams define how individual signature field" [Ma00]. Streams define how individual
packet's statistics are grouped together to form an packets' statistic are grouped together to form an
intelligible summary. intelligible summary.
Common stream groupings would be by egress interface, Common stream groupings would be by egress interface,
destination address, source address, DSCP, or IP precedence. destination address, source address, DSCP, or IP precedence.
A stream using test sequence numbers can track the ordering A stream using test sequence numbers can track the ordering
of packets as they transverse the DUT/SUT. of packets as they transverse the DUT/SUT.
Streams are not restricted to a pair of source and Streams are not restricted to a pair of source and
destination interfaces as long as all packets are tracked as destination interfaces as long as all packets are tracked as
a single entity. A mulitcast stream can be forward to a single entity. A mulitcast stream can be forward to
multiple destination interfaces. multiple destination interfaces.
Measurement units: Measurement units:
n/a n/a
See Also: See Also:
Flow Flow
MicroFlow [Ni98] Microflow [Ni98]
Test sequence number Test sequence number
Network-layer Traffic Control Mechanisms
3.3.6 Test Sequence number 3.3.5 Test Sequence number
Definition: Definition:
A field in the IP payload portion of the packet that is used A field in the IP payload portion of the packet that is used
to verify the order of the packets on the egress of the to verify the order of the packets on the egress of the
DUT/SUT. DUT/SUT.
Network-layer Traffic Control Mechanisms
Discussion: Discussion:
The traffic generator sets the test sequence number value and The traffic generator sets the test sequence number value and
the traffic receiver checks the value upon receipt of the the traffic receiver checks the value upon receipt of the
packet. The traffic generator changes the value on each packet. The traffic generator changes the value on each
packet transmitted based on an algorithm agreed to by the packet transmitted based on an algorithm agreed to by the
traffic receiver. traffic receiver.
The traffic receiver keeps track of the sequence numbers on a The traffic receiver keeps track of the sequence numbers on a
per stream basis. In addition to number of received packets, per stream basis. In addition to number of received packets,
the traffic receiver may also report number of in-sequence the traffic receiver may also report number of in-sequence
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3.4 Vectors 3.4 Vectors
A vector is a group of packets all containing a specific DSCP A vector is a group of packets all containing a specific DSCP
or IP precedence value. Vectors are expressed as a pair of or IP precedence value. Vectors are expressed as a pair of
numbers. The first is being the particular diff-serv value. numbers. The first is being the particular diff-serv value.
The second is the metric expressed as a rate, loss The second is the metric expressed as a rate, loss
percentage, delay, or jitter. percentage, delay, or jitter.
3.4.1 Intended Vector 3.4.1 Intended Vector
Definition: Definition:
A vector describing the rate at which packets having a A vector describing the attempted rate at which packets
specific code-point (or IP precedence) that an external having a specific code-point (or IP precedence) are
source attempts to transmit to a DUT/SUT. transmitted to a DUT/SUT by an external source.
Discussion: Discussion:
Intended loads across the different code-point classes Intended loads across the different code-point classes
determine the metrics associated with a specific code-point determine the metrics associated with a specific code-point
traffic class. traffic class.
Network-layer Traffic Control Mechanisms
Measurement Units: Measurement Units:
N-octets packets per second N-octets packets per second
Network-layer Traffic Control Mechanisms
See Also: See Also:
Offered Vector Offered Vector
Expected Forwarding Vector Expected Forwarding Vector
Expected Loss Vector Expected Loss Vector
Expected Sequence Vector Expected Sequence Vector
Expected Delay Vector Expected Delay Vector
Expected Jitter Vector Expected Jitter Vector
Forwarding Vector Forwarding Vector
Loss Vector Loss Vector
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having a specific DSCP or IP precedence value. The value is having a specific DSCP or IP precedence value. The value is
dependent on the set of offered vectors and configuration of dependent on the set of offered vectors and configuration of
the DUT. the DUT.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected forwarding vector. expected forwarding vector.
Measurement units: Measurement units:
N-octet packets per second N-octet packets per second
See Also: See Also:
Intended Vector Intended Vector
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Definition: Definition:
A vector describing the percentage of packets, having a A vector describing the percentage of packets, having a
specific DSCP or IP precedence value, that should not be specific DSCP or IP precedence value, that should not be
forwarded. The value is dependent on the set of offered forwarded. The value is dependent on the set of offered
vectors and configuration of the DUT. vectors and configuration of the DUT.
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vector. subjected to a certain offered vector.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected loss vector. expected loss vector.
Measurement Units: Measurement Units:
Percentage of intended packets that are expected to be Percentage of intended packets that is expected to be
dropped. dropped.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Forwarding Vector Expected Forwarding Vector
Expected Sequence Vector Expected Sequence Vector
Expected Delay Vector Expected Delay Vector
Expected Jitter Vector Expected Jitter Vector
One-way Packet Loss Metric [Ka99] One-way Packet Loss Metric [Ka99]
3.2.3.3 Expected Sequence Vector 3.4.3.3 Expected Sequence Vector
Definition: Definition:
A vector describing the expected in-sequence packets having a A vector describing the expected in-sequence packets having a
specific DSCP or IP precedence value. The value is dependent specific DSCP or IP precedence value. The value is dependent
on the set of offered vectors and configuration of the DUT. on the set of offered vectors and configuration of the DUT.
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected sequence vector. expected sequence vector.
Measurement Units: Measurement Units:
N-octet packets per second N-octet packets per second
See Also: See Also:
Intended Vector Intended Vector
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A vector describing the expected delay for packets having a A vector describing the expected delay for packets having a
specific DSCP or IP precedence value. The value is dependent specific DSCP or IP precedence value. The value is dependent
on the set of offered vectors and configuration of the DUT. on the set of offered vectors and configuration of the DUT.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected delay vector. expected delay vector.
Measurement units: Measurement units:
Seconds. Seconds.
See Also: See Also:
Forwarding Delay Forwarding Delay
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Definition: Definition:
A vector describing the expected average delay for packets A vector describing the expected average delay for packets
having a specific DSCP or IP precedence value. The value is having a specific DSCP or IP precedence value. The value is
dependent on the set of offered vectors and configuration of dependent on the set of offered vectors and configuration of
the DUT. the DUT.
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected average delay vector. expected average delay vector.
Measurement units: Measurement units:
Seconds. Seconds.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
skipping to change at page 19, line 28 skipping to change at page 20, line 28
Definition: Definition:
A vector describing the expected maximum delay for packets A vector describing the expected maximum delay for packets
having a specific DSCP or IP precedence value. The value is having a specific DSCP or IP precedence value. The value is
dependent on the set of offered vectors and configuration of dependent on the set of offered vectors and configuration of
the DUT. the DUT.
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected maximum delay vector. expected maximum delay vector.
Measurement units: Measurement units:
Seconds. Seconds.
See Also: See Also:
Intended Vector Intended Vector
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having a specific DSCP or IP precedence value. The value is having a specific DSCP or IP precedence value. The value is
dependent on the set of offered vectors and configuration of dependent on the set of offered vectors and configuration of
the DUT. the DUT.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
Discussion: Discussion:
The DUT is configured in a certain way in order that service The DUT is configured in a certain way in order that service
differentiation occurs for a particular DSCP or IP precedence differentiation occurs for a particular DSCP or IP precedence
value when a specific traffic mix consisting of multiple value when a specific traffic mix consisting of multiple
DSCPs or IP precedence values are applied. This term attempts DSCPs or IP precedence values are applied. This term
to capture the expected forwarding behavior when subjected to attempts to capture the expected forwarding behavior when
a certain offered vectors. subjected to a certain offered vectors.
The actual algorithm or mechanism the DUT uses to achieve The actual algorithm or mechanism the DUT uses to achieve
service differentiation is not important in describing the service differentiation is not important in describing the
expected minimum delay vector. expected minimum delay vector.
Measurement units: Measurement units:
Seconds. Seconds.
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Output Vectors Output Vectors
Expected Loss Vector Expected Loss Vector
Expected Sequence Vector Expected Sequence Vector
Expected Forwarding Vector Expected Forwarding Vector
Expected Jitter Vector Expected Jitter Vector
3.2.3.8 Expected Instantaneous Jitter Vector 3.4.3.8 Expected Instantaneous Jitter Vector
Definition: Definition:
A vector describing the expected jitter between two A vector describing the expected jitter between two
consecutive packets' arrival times having a specific DSCP or consecutive packets' arrival times having a specific DSCP or
IP precedence value. The value is dependent on the set of IP precedence value. The value is dependent on the set of
offered vectors and configuration of the DUT. offered vectors and configuration of the DUT.
Discussion: Discussion:
Instantaneous Jitter is the absolute value of the difference Instantaneous Jitter is the absolute value of the difference
between the delay measurement of two packets belonging to the between the delay measurement of two packets belonging to the
skipping to change at page 21, line 15 skipping to change at page 22, line 15
See Also: See Also:
Delay Delay
Jitter Jitter
Offered Vector Offered Vector
Output Vectors Output Vectors
Expected Average Jitter Vector Expected Average Jitter Vector
Expected Peak-to-peak Jitter Vector Expected Peak-to-peak Jitter Vector
Stream Stream
3.2.3.9 Expected Average Jitter Vector 3.4.3.9 Expected Average Jitter Vector
Definition: Definition:
A vector describing the expected jitter in packet arrival A vector describing the expected jitter in packet arrival
times for packets having specific DSCP or IP precedence times for packets having a specific DSCP or IP precedence
value. The value is dependent on the set of offered vectors value. The value is dependent on the set of offered vectors
and configuration of the DUT. and configuration of the DUT.
Discussion: Discussion:
Average Jitter Vector is the average of all the Instantaneous Average Jitter Vector is the average of all the Instantaneous
Jitter Vectors measured during the test duration for the same Jitter Vectors measured during the test duration for the same
DSCP or IP precedence value. DSCP or IP precedence value.
Measurement units: Measurement units:
Seconds Seconds
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Output Vectors Output Vectors
Expected Instantaneous Jitter Vector Expected Instantaneous Jitter Vector
Expected Peak-to-peak Jitter Vector Expected Peak-to-peak Jitter Vector
3.2.3.10 Expected Peak-to-peak Jitter Vector 3.4.3.10 Expected Peak-to-peak Jitter Vector
Definition: Definition:
A vector describing the expected maximum variation in the A vector describing the expected maximum variation in the
delay of packet arrival times for packets having specific delay of packet arrival times for packets having a specific
DSCP or IP precedence value. The value is dependent on the DSCP or IP precedence value. The value is dependent on the
set of offered vectors and configuration of the DUT. set of offered vectors and configuration of the DUT.
Discussion: Discussion:
Peak-to-peak Jitter Vector is the maximum delay minus the Peak-to-peak Jitter Vector is the maximum delay minus the
minimum delay of the packets (in a vector) forwarded by the minimum delay of the packets (in a vector) forwarded by the
DUT/SUT. DUT/SUT.
Peak-to-peak Jitter is not derived from the Instantaneous Peak-to-peak Jitter is not derived from the Instantaneous
Jitter Vector. Peak-to-peak Jitter is based upon all the Jitter Vector. Peak-to-peak Jitter is based upon all the
Network-layer Traffic Control Mechanisms
packets during the test duration, not just two consecutive packets during the test duration, not just two consecutive
packets. packets.
Network-layer Traffic Control Mechanisms
Measurement units: Measurement units:
Seconds Seconds
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Output Vectors Output Vectors
Expected Instantaneous Jitter Vector Expected Instantaneous Jitter Vector
Expected Average Jitter Vector Expected Average Jitter Vector
skipping to change at page 22, line 37 skipping to change at page 23, line 35
interface in response to an offered vector. interface in response to an offered vector.
Discussion: Discussion:
Forwarding Vector is expressed as pair of numbers. Both the Forwarding Vector is expressed as pair of numbers. Both the
specific DSCP (or IP precedence) value AND the packets per specific DSCP (or IP precedence) value AND the packets per
second value combine to make a vector. second value combine to make a vector.
The Forwarding Vector represents packet rate based on its The Forwarding Vector represents packet rate based on its
specific DSCP (or IP precedence) value. It is not specific DSCP (or IP precedence) value. It is not
necessarily based on a stream or flow. The Forwarding Vector necessarily based on a stream or flow. The Forwarding Vector
may be expressed as per port of the DUT/SUT. However, it must may be expressed as per port of the DUT/SUT. However, it
be consistent with the Expected Forwarding Vector. must be consistent with the Expected Forwarding Vector.
Forwarding Vector is a per-hop measurement. The DUT/SUT may Forwarding Vector is a per-hop measurement. The DUT/SUT may
change the specific DSCP (or IP precedence) value for a change the specific DSCP (or IP precedence) value for a
multiple-hop measurement. multiple-hop measurement.
Measurement units: Measurement units:
N-octet packets per second N-octet packets per second
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Vectors Expected Vectors
Loss Vector Loss Vector
Sequence Vector Sequence Vector
Delay Vectors Delay Vectors
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
3.4.4.2 Loss Vector 3.4.4.2 Loss Vector
Definition: Definition:
The percentage of packets containing specific DSCP or IP The percentage of packets containing a specific DSCP or IP
precedence value that a DUT/SUT did not transmit to the precedence value that a DUT/SUT did not transmit to the
correct destination interface in response to an offered correct destination interface in response to an offered
vector. vector.
Discussion: Discussion:
Loss Vector is expressed as pair of numbers. Both the Loss Vector is expressed as pair of numbers. Both the
specific DSCP (or IP precedence) value AND the percentage specific DSCP (or IP precedence) value AND the percentage
value combine to make a vector. value combine to make a vector.
The Loss Vector represents percentage based on a specific The Loss Vector represents percentage based on a specific
DSCP or IP precedence value. It is not necessarily based on DSCP or IP precedence value. It is not necessarily based on
a stream or flow. The Loss Vector may be expressed as per a stream or flow. The Loss Vector may be expressed as per
port of the DUT/SUT. However, it must be consistent with the port of the DUT/SUT. However, it must be consistent with the
Expected Loss Vector Expected Loss Vector
Loss Vector is a per-hop measurement. The DUT/SUT may change Loss Vector is a per-hop measurement. The DUT/SUT may change
the specific DSCP or IP precedence value for a multiple-hop the specific DSCP or IP precedence value for a multiple-hop
measurement. measurement.
Measurement Units: Measurement Units:
Percentage of offered packets that are not forwarded. Percentage of offered packets that is not forwarded.
See Also: See Also:
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Vectors Expected Vectors
Forwarding Vector Forwarding Vector
Sequence Vector Sequence Vector
Delay Vectors Delay Vectors
One-way Packet Loss Metric [Ka99] One-way Packet Loss Metric [Ka99]
skipping to change at page 24, line 34 skipping to change at page 25, line 34
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Vectors Expected Vectors
Loss Vector Loss Vector
Forwarding Vector Forwarding Vector
Delay Vectors Delay Vectors
3.4.4.4 Instantaneous Delay Vector 3.4.4.4 Instantaneous Delay Vector
Definition: Definition:
The delay for a packet containing specific DSCP or IP The delay for a packet containing a specific DSCP or IP
precedence value that a device can be observed to precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Discussion: Discussion:
Instantaneous Delay vector is expressed as pair of numbers. Instantaneous Delay vector is expressed as pair of numbers.
Both the specific DSCP (or IP precedence) value AND delay Both the specific DSCP (or IP precedence) value AND delay
value combine to make a vector. value combine to make a vector.
The Instantaneous Delay Vector represents delay on its The Instantaneous Delay Vector represents delay on its
specific DSCP or IP precedence value. It is not necessarily specific DSCP or IP precedence value. It is not necessarily
based on a stream or flow. The Delay vector may be expressed based on a stream or flow. The Delay vector may be expressed
as per port of the DUT/SUT. However, it must be consistent as per port of the DUT/SUT. However, it must be consistent
with the Expected Delay vectors. with the Expected Delay vectors.
Instantaneous Delay Vector is a per-hop measurement. The Instantaneous Delay Vector is a per-hop measurement. The
DUT/SUT may change the specific DSCP or IP precedence value DUT/SUT may change the specific DSCP or IP precedence value
for a multiple-hop measurement. for a multiple-hop measurement.
Network-layer Traffic Control Mechanisms
Instantaneous Delay vector can be obtained at any offered Instantaneous Delay vector can be obtained at any offered
load. Recommend at or below the channel capacity in the load. RECOMMEND at or below the channel capacity in the
absence of congestion. For congested delay, run the offered absence of forwarding congestion. For congested delay, run
load above the channel capacity. the offered load above the channel capacity.
Network-layer Traffic Control Mechanisms
Forwarding Vector may contain several Instantaneous Delay Forwarding Vector may contain several Instantaneous Delay
Vectors. For every packet received in a Forwarding Vector, Vectors. For every packet received in a Forwarding Vector,
there is a corresponding Instantaneous Delay Vector. there is a corresponding Instantaneous Delay Vector.
Measurement Units: Measurement Units:
Seconds Seconds
See Also: See Also:
Delay Delay
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Delay Vectors Expected Delay Vectors
Average Delay Vector Average Delay Vector
Maximum Delay Vector Maximum Delay Vector
Minimum Delay Vector Minimum Delay Vector
3.4.4.5 Average Delay Vector 3.4.4.5 Average Delay Vector
Definition: Definition:
The average delay for packets containing specific DSCP or IP The average delay for packets containing a specific DSCP or
precedence value that a device can be observed to IP precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Discussion: Discussion:
Average Delay vector is expressed as pair of numbers. Both Average Delay vector is expressed as pair of numbers. Both
the specific DSCP (or IP precedence) value AND delay value the specific DSCP (or IP precedence) value AND delay value
combine to make a vector. combine to make a vector.
The Delay Vector represents delay on its specific DSCP or IP The Delay Vector represents delay on its specific DSCP or IP
precedence value. It is not necessarily based on a stream or precedence value. It is not necessarily based on a stream or
flow. The Delay vector may be expressed as per port of the flow. The Delay vector may be expressed as per port of the
DUT/SUT. However, it must be consistent with the Expected DUT/SUT. However, it MUST be consistent with the Expected
Delay vector. Delay vector.
The Average Delay Vector is computed by averaging all the The Average Delay Vector is computed by averaging all the
Instantaneous Delay Vectors for a given vector. Instantaneous Delay Vectors for a given vector.
Average Delay Vector is a per-hop measurement. The DUT/SUT Average Delay Vector is a per-hop measurement. The DUT/SUT
may change the specific DSCP or IP precedence value for a may change the specific DSCP or IP precedence value for a
multiple-hop measurement. multiple-hop measurement.
Average Delay vector can be obtained at any offered load. Average Delay vector can be obtained at any offered load.
Recommend at or below the channel capacity in the absence of Recommend at or below the channel capacity in the absence of
congestion. For congested delay, run the offered load above congestion. For congested delay, run the offered load above
the channel capacity. the channel capacity.
Network-layer Traffic Control Mechanisms
Measurement Units: Measurement Units:
Seconds Seconds
Network-layer Traffic Control Mechanisms
See Also: See Also:
Delay Delay
Intended Vector Intended Vector
Offered Vector Offered Vector
Expected Delay Vectors Expected Delay Vectors
Instantaneous Delay Vector Instantaneous Delay Vector
Maximum Delay Vector Maximum Delay Vector
Minimum Delay Vector Minimum Delay Vector
3.4.4.6 Maximum Delay Vector 3.4.4.6 Maximum Delay Vector
Definition: Definition:
The maximum delay from all packets containing specific DSCP The maximum delay from all packets containing a specific DSCP
or IP precedence value that a device can be observed to or IP precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Discussion: Discussion:
Maximum Delay vector is expressed as pair of numbers. Both Maximum Delay vector is expressed as pair of numbers. Both
the specific DSCP (or IP precedence) value AND delay value the specific DSCP (or IP precedence) value AND delay value
combine to make a vector. combine to make a vector.
The Maximum Delay Vector represents delay on its specific The Maximum Delay Vector represents delay on its specific
skipping to change at page 27, line 9 skipping to change at page 28, line 9
Expected Delay Vectors Expected Delay Vectors
Instantaneous Delay Vector Instantaneous Delay Vector
Forwarding Vector Forwarding Vector
Average Delay Vector Average Delay Vector
Minimum Delay Vector Minimum Delay Vector
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
3.4.4.7 Minimum Delay Vector 3.4.4.7 Minimum Delay Vector
Definition: Definition:
The minimum delay from all packets containing specific DSCP The minimum delay from all packets containing a specific DSCP
or IP precedence value that a device can be observed to or IP precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Discussion: Discussion:
Delay vector is expressed as pair of numbers. Both the Delay vector is expressed as pair of numbers. Both the
specific DSCP (or IP precedence) value AND delay value specific DSCP (or IP precedence) value AND delay value
combine to make a vector. combine to make a vector.
The Minimum Delay Vector represents delay on its specific The Minimum Delay Vector represents delay on its specific
skipping to change at page 28, line 4 skipping to change at page 28, line 53
Offered Vector Offered Vector
Expected Delay Vectors Expected Delay Vectors
Instantaneous Delay Vector Instantaneous Delay Vector
Forwarding Vector Forwarding Vector
Average Delay Vector Average Delay Vector
Maximum Delay Vector Maximum Delay Vector
3.4.4.8 Instantaneous Jitter Vector 3.4.4.8 Instantaneous Jitter Vector
Definition: Definition:
The jitter for two consecutive packets containing a specific
Network-layer Traffic Control Mechanisms
The jitter for two consecutive packets containing specific
DSCP or IP precedence value that a device can be observed to DSCP or IP precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Network-layer Traffic Control Mechanisms
Discussion: Discussion:
Instantaneous Jitter is the absolute value of the difference Instantaneous Jitter is the absolute value of the difference
between the delay measurement of two packets belonging to the between the delay measurement of two packets belonging to the
same stream. same stream.
Jitter vector is expressed as pair of numbers. Both the Jitter vector is expressed as pair of numbers. Both the
specific DSCP (or IP precedence) value AND jitter value specific DSCP (or IP precedence) value AND jitter value
combine to make a vector. combine to make a vector.
The delay fluctuation between two consecutive packets in a The delay fluctuation between two consecutive packets in a
skipping to change at page 28, line 50 skipping to change at page 29, line 45
Jitter Jitter
Forwarding Vector Forwarding Vector
Stream Stream
Expected Vectors Expected Vectors
Average Jitter Vector Average Jitter Vector
Peak-to-peak Jitter Vector Peak-to-peak Jitter Vector
3.4.4.9 Average Jitter Vector 3.4.4.9 Average Jitter Vector
Definition: Definition:
The average jitter for packets containing specific DSCP or IP The average jitter for packets containing a specific DSCP or
precedence value that a device can be observed to IP precedence value that a device can be observed to
successfully transmit to the correct destination interface in successfully transmit to the correct destination interface in
response to an offered vector. response to an offered vector.
Discussion: Discussion:
Network-layer Traffic Control Mechanisms
Average Jitter Vector is the average of all the Instantaneous Average Jitter Vector is the average of all the Instantaneous
Jitter Vectors of the same DSCP or IP precedence value, Jitter Vectors of the same DSCP or IP precedence value,
measured during the test duration. measured during the test duration.
Network-layer Traffic Control Mechanisms
Average Jitter vector is expressed as pair of numbers. Both Average Jitter vector is expressed as pair of numbers. Both
the specific DSCP (or IP precedence) value AND jitter value the specific DSCP (or IP precedence) value AND jitter value
combine to make a vector. combine to make a vector.
Average Jitter vector is a per-hop measurement. The DUT/SUT Average Jitter vector is a per-hop measurement. The DUT/SUT
may change the specific DSCP or IP precedence value for a may change the specific DSCP or IP precedence value for a
multiple-hop measurement. multiple-hop measurement.
Measurement units: Measurement units:
Seconds Seconds
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Forwarding Vector Forwarding Vector
Stream Stream
Expected Vectors Expected Vectors
Instantaneous Jitter Vector Instantaneous Jitter Vector
Peak-to-peak Jitter Vector Peak-to-peak Jitter Vector
3.4.4.10 Peak-to-peak Jitter Vector 3.4.4.10 Peak-to-peak Jitter Vector
Definition: Definition:
The maximum possible variation in the delay for packets The maximum possible variation in the delay for packets
containing specific DSCP or IP precedence value that a device containing a specific DSCP or IP precedence value that a
can be observed to successfully transmit to the correct device can be observed to successfully transmit to the
destination interface in response to an offered vector. correct destination interface in response to an offered
vector.
Discussion: Discussion:
Peak-to-peak Jitter Vector is the maximum delay minus the Peak-to-peak Jitter Vector is the maximum delay minus the
minimum delay of the packets (in a vector) forwarded by the minimum delay of the packets (in a vector) forwarded by the
DUT/SUT. DUT/SUT.
Jitter vector is expressed as pair of numbers. Both the Jitter vector is expressed as pair of numbers. Both the
specific DSCP (or IP precedence) value AND jitter value specific DSCP (or IP precedence) value AND jitter value
combine to make a vector. combine to make a vector.
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Jitter Vector. Peak-to-peak Jitter is based upon all the Jitter Vector. Peak-to-peak Jitter is based upon all the
packets during the test duration, not just two consecutive packets during the test duration, not just two consecutive
packets. packets.
Measurement units: Measurement units:
Seconds Seconds
See Also: See Also:
Jitter Jitter
Forwarding Vector Forwarding Vector
Network-layer Traffic Control Mechanisms
Stream Stream
Expected Vectors Expected Vectors
Average Jitter Vector Average Jitter Vector
Peak-to-peak Jitter Vector Peak-to-peak Jitter Vector
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
4. Security Considerations 4. Acknowledgments
The editors gratefully acknowledge the contributions of the
IETF's benchmarking working group members in reviewing this
document. The following individuals also made noteworthy
contributions to the editors' understanding of the subject
matter: John Dawson, Kevin Dubray, and Kathleen Nichols.
5. 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 of corporate networks as long as benchmarking the Internet or of corporate networks as long as benchmarking
is not performed on devices or systems connected to is not performed on devices or systems connected to
production networks. production networks.
Packets with unintended and/or unauthorized DSCP or IP Packets with unintended and/or unauthorized DSCP or IP
precedence values may present security issues. Determining precedence values may present security issues. Determining
the security consequences of such packets is out of scope for the security consequences of such packets is out of scope for
this document. this document.
5. Acknowledgments
The editors gratefully acknowledge the contributions of the
IETF's benchmarking working group members in reviewing this
document. The following individuals also made noteworthy
contributions to the editors' understanding of the subject
matter: John Dawson, Kevin Dubray, and Kathleen Nichols.
6. Normative References 6. Normative References
[Br91] Bradner, S., Editor, "Benchmarking Terminology for [Br91] Bradner, S., "Benchmarking Terminology for Network
Network Interconnection Devices", RFC 1242, July 1991. Interconnection Devices", RFC 1242, July 1991.
[Br97] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997
[Ma98] Mandeville, R., "Benchmarking Terminology for LAN [Ma98] Mandeville, R., "Benchmarking Terminology for LAN
Switching Devices", RFC 2285, February 1998. Switching Devices", RFC 2285, February 1998.
[Ni98] K. Nichols, S. Blake, F. Baker, D. Black,"Definition of [Ni98] Nichols, K., Blake, S., Baker, F., Black, D., "Definition
the Differentiated Services Field (DS Field) in the IPv4 of the Differentiated Services Field (DS Field) in the
and IPv6 Headers", RFC 2474, December 1998. IPv4 and IPv6 Headers", RFC 2474, December 1998.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
7. Informative References 7. Informative References
[Al99] Almes, G., Kalidindi, S., Zekauskas, M., _A One-way Delay [Al99] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way Delay
Metric for IPPM_, RFC 2679, September 1999 Metric for IPPM", RFC 2679, September 1999
[Bl98] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. [Bl98] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
Weiss, "An Architecture for Differentiated Services", Weiss, W., "An Architecture for Differentiated Services",
RFC 2475, December 1998. RFC 2475, December 1998.
[Br99] Bradner, S., McQuaid, J. _Benchmarking Methodology for [Br99] Bradner, S., McQuaid, J. "Benchmarking Methodology for
Network Interconnect Devices_, RFC 2544, March 1999 Network Interconnect Devices", RFC 2544, March 1999
[De02] C. Demichelis, P. Chimento, _IP Packet Delay Variation [De02] Demichelis, C., Chimento, P., "IP Packet Delay Variation
Metric for IPPM_, RFC 3393, November 2002 Metric for IPPM", RFC 3393, November 2002
[Ja99] V. Jacobson, K. Nichols, K. Poduri, _An Expedited [Ja99] Jacobson, V., Nichols, K., Poduri, K., "An Expedited
Forwarding PHB_, RFC 2598, June 1999 Forwarding PHB", RFC 2598, June 1999
[Ka99] Almes, G., Kalidindi, S., Zekauskas, M., _A One-way [Ka99] Almes, G., Kalidindi, S., Zekauskas, M., "A One-way
Packet Loss Metric for IPPM_, RFC 2680, September 1999 Packet Loss Metric for IPPM", RFC 2680, September 1999
[Ma91] A. Mankin, K. Ramakrishnan, _Gateway Congestion Control [Ma91] Mankin, A., Ramakrishnan, K., "Gateway Congestion Control
Survey_, RFC 1254, August 1991 Survey", RFC 1254, August 1991
[Ma00] R. Mandeville, J. Perser, _Benchmarking Methodology for [Ma00] Mandeville, R., Perser, J., "Benchmarking Methodology for
LAN Switching Devices_, RFC 2889, August 2000 LAN Switching Devices", RFC 2889, August 2000
[Na84] Nagle, John, "Congestion Control in IP/TCP [Mo03] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
Internetworks", RFC 896, January 1984. S., Perser, J., "Packet Reordering Metric for IPPM",
Work in Progress
[Na84] Nagle, J., "Congestion Control in IP/TCP Internetworks",
RFC 896, January 1984.
[Ra99] Ramakrishnan, K. and Floyd, S., "A Proposal to add [Ra99] Ramakrishnan, K. and Floyd, S., "A Proposal to add
Explicit Congestion Notification (ECN) to IP", RFC 2481, Explicit Congestion Notification (ECN) to IP", RFC 2481,
January 1999. January 1999.
[Sc96] H. Schulzrinne, GMD Fokus, S. Casner, R. Frederick, [Sc96] Schulzrinne, H., Casner, S., Frederick, R., Jacobson, V.,
V. Jacobson, _RTP: A Transport Protocol for Real-Time "RTP: A Transport Protocol for Real-Time Applications",
Applications_, RFC 1889, January 1996 RFC 1889, January 1996
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
8. Authors' Address 8. Authors' Addresses
Jerry Perser Jerry Perser
Spirent Communications Spirent Communications
26750 Agoura Road 26750 Agoura Road
Calabasas, CA 91302 Calabasas, CA 91302
USA USA
Phone: + 1 818 676 2300 Phone: + 1 818 676 2300
EMail: jerry.perser@spirentcom.com EMail: jerry.perser@spirentcom.com
skipping to change at page 33, line 38 skipping to change at page 33, line 38
445 South Street 445 South Street
Morristown, NJ 07960 Morristown, NJ 07960
USA USA
Phone: + 1 973 829 3170 Phone: + 1 973 829 3170
EMail: sumit@research.telcordia.com EMail: sumit@research.telcordia.com
Shobha Erramilli Shobha Erramilli
QNetworx Inc QNetworx Inc
1119 Campus Drive West 1119 Campus Drive West
Morganville NJ 07751 Morganville, NJ 07751
USA USA
Phone: Phone:
EMail: shobha@qnetworx.com EMail: shobha@qnetworx.com
Scott Poretsky Scott Poretsky
Avici Systems Avici Systems
101 Billerica Ave_Building #6 101 Billerica Ave_Building #6
N. Billerica, MA 01862 N. Billerica, MA 01862
USA USA
Phone: + 1 978 964 2287 Phone: + 1 978 964 2287
EMail: sporetsky@avici.com EMail: sporetsky@avici.com
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
9. Full Copyright Statement 9. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Copyright (C) The Internet Society (2003). All Rights
Reserved. Reserved.
This document and translations of it may be copied and This document and translations of it may be copied and
furnished to others, and derivative works that comment on or furnished to others, and derivative works that comment on or
otherwise explain it or assist in its implementation may be otherwise explain it or assist in its implementation may be
prepared, copied, published and distributed, in whole or in prepared, copied, published and distributed, in whole or in
part, without restriction of any kind, provided that the part, without restriction of any kind, provided that the
above copyright notice and this paragraph are included on all above copyright notice and this paragraph are included on all
such copies and derivative works. However, this document such copies and derivative works. However, this document
itself may not be modified in any way, such as by removing itself may not be modified in any way, such as by removing
 End of changes. 

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