draft-ietf-bmwg-dsmterm-05.txt   draft-ietf-bmwg-dsmterm-06.txt 
Network Working Group Jerry Perser Network Working Group Jerry Perser
INTERNET-DRAFT Spirent INTERNET-DRAFT Spirent
Expires in: August 2003 David Newman Expires in: November 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
February 2002 April 2003
Terminology for Benchmarking Network-layer Terminology for Benchmarking Network-layer
Traffic Control Mechanisms Traffic Control Mechanisms
<draft-ietf-bmwg-dsmterm-05.txt> <draft-ietf-bmwg-dsmterm-06.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 2, line 9 skipping to change at page 2, line 9
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 ...................................................6
3.2 Measurement Terms 3.2 Measurement Terms
Network-layer Traffic Control Mechanisms 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 .............................................8
3.2.3 Nonconforming ..........................................8 3.2.3 Nonconforming ..........................................8
3.2.4 Delay ..................................................9 3.2.4 Forwarding Delay .......................................9
3.2.5 Jitter ................................................10 3.2.5 Jitter ................................................10
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 ....................................11
3.3.2 Out-of-order Packet ...................................12 3.3.2 Out-of-order Packet ...................................12
3.3.3 Duplicate Packet ......................................12 3.3.3 Duplicate Packet ......................................13
3.3.4 Stream ................................................13 3.3.4 Stream ................................................13
3.3.5 Test Sequence number .................................13 3.3.5 Test Sequence number .................................14
3.4 Vectors ...................................................14 3.4 Vectors ...................................................14
3.4.1 Intended Vector .......................................14 3.4.1 Intended Vector .......................................14
3.4.2 Offered Vector ........................................15 3.4.2 Offered Vector ........................................15
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 ........................15
3.4.3.2 Expected Loss Vector ..............................16 3.4.3.2 Expected Loss Vector ..............................16
3.4.3.3 Expected Sequence Vector ..........................16 3.4.3.3 Expected Sequence Vector ..........................17
3.4.3.4 Expected Instantaneous Delay Vector ...............17 3.4.3.4 Expected Instantaneous Delay Vector ...............17
3.4.3.5 Expected Average Delay Vector .....................18 3.4.3.5 Expected Average Delay Vector .....................18
3.4.3.6 Expected Maximum Delay Vector .....................18 3.4.3.6 Expected Maximum Delay Vector .....................19
3.4.3.7 Expected Minimum Delay Vector .....................19 3.4.3.7 Expected Minimum Delay Vector .....................19
3.4.3.8 Expected Instantaneous Jitter Vector ..............20 3.4.3.8 Expected Instantaneous Jitter Vector ..............20
3.4.3.9 Expected Average Jitter Vector ....................21 3.4.3.9 Expected Average Jitter Vector ....................21
3.4.3.10 Expected Peak-to-peak Jitter Vector ..............21 3.4.3.10 Expected Peak-to-peak Jitter Vector ..............21
3.4.4 Output Vectors 3.4.4 Output Vectors
3.4.4.1 Forwarding Vector .................................22 3.4.4.1 Forwarding Vector .................................22
3.4.4.2 Loss Vector .......................................22 3.4.4.2 Loss Vector .......................................23
3.4.4.3 Sequence Vector ...................................23 3.4.4.3 Sequence Vector ...................................23
3.4.4.4 Instantaneous Delay Vector ........................24 3.4.4.4 Instantaneous Delay Vector ........................24
3.4.4.5 Average Delay Vector ..............................25 3.4.4.5 Average Delay Vector ..............................25
3.4.4.6 Maximum Delay Vector ..............................26 3.4.4.6 Maximum Delay Vector ..............................26
3.4.4.7 Minimum Delay Vector ..............................26 3.4.4.7 Minimum Delay Vector ..............................27
3.4.4.8 Instantaneous Jitter Vector .......................27 3.4.4.8 Instantaneous Jitter Vector .......................27
3.4.4.9 Average Jitter Vector .............................28 3.4.4.9 Average Jitter Vector .............................28
3.4.4.10 Peak-to-peak Jitter Vector .......................29 3.4.4.10 Peak-to-peak Jitter Vector .......................29
4. Security Considerations ....................................30 4. Security Considerations ....................................30
5. Normative References .......................................30 5. Acknowledgments ............................................30
6. Informative References .....................................31 6. Normative References .......................................30
7. Author's Address ...........................................32 7. Informative References .....................................31
8. Full Copyright Statement ...................................33 8. Author's Address ...........................................32
9. Full Copyright Statement ...................................33
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
1. Introduction 1. Introduction
This document describes terminology for the benchmarking of This document describes terminology for the benchmarking of
devices that implement traffic control based on IP precedence or devices that implement traffic control based on IP precedence or
diff-serv code point criteria. 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-
skipping to change at page 5, line 16 skipping to change at page 5, line 16
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 definition assumes the congestion is [Ma98]. The overload discussion deals with how many input
introduced strictly by the tester on ingress of a DUT/SUT. interfaces are required to overload the output interfaces.
That may or may not be the case here. Forwarding congestion does not assume ingress 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, the
edge devices may induce congestion on multiple egress edge devices may induce Forwarding Congestion on multiple
interfaces on the core device. In contrast, overload [Br91] egress interfaces on the core device.
deals only with overload on ingress.
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. [Ra99] states that it is impractical to build a
black-box test to externally observe Incipient Congestion in black-box test to externally observe Incipient Congestion in
a router. For the purpose of "black-box" testing a DUT/SUT, a router. For the purpose of "black-box" testing a DUT/SUT,
Packet Loss as the indicator of Forwarding Congestion is Packet Loss as the indicator of Forwarding Congestion is
used. 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, Forwarding Congestion. At offered rates above throughput, the
the DUT/SUT is considered congested. DUT/SUT is considered to be in a state of Forwarding
Congestion.
Ingress observations alone are not sufficient to cover all Ingress observations alone are not sufficient to cover all
cases in which Forwarding Congestion may occur. A device with cases in which Forwarding Congestion may occur. A device with
an infinite amount of memory could buffer an infinite amount an infinite amount of memory could buffer an infinite amount
of packets, and eventually forward all of them. However, of packets, and eventually forward all of them. However,
these packets may or may not be forwarded during the test these packets may or may not be forwarded during the test
duration. Even though ingress interfaces accept all packets duration. Even though ingress interfaces accept all packets
without loss, this hypothetical device may still be without loss, Forwarding Congestion is present in this
congested. hypothetical device.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
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.
skipping to change at page 7, line 5 skipping to change at page 6, line 56
n/a n/a
See Also: See Also:
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:
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
Discussion:
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
skipping to change at page 7, line 49 skipping to change at page 7, line 48
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.
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 is based on the defined in RFC 1242 measures the packet rate at the ingress
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, does
take congestion into account. take congestion into account.
Network-layer Traffic Control Mechanisms 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 congestion. Throughput numbers can
be higher than channel capacity because of queueing. be higher than channel capacity because of queueing.
skipping to change at page 9, line 16 skipping to change at page 9, line 16
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 Delay 3.2.4 Forwarding Delay
Definition: Definition:
The time interval starting when the last bit of the input IP The time interval starting when the last bit of the input IP
packet reaches the input port of the DUT/SUT and ending when packet is offered to the input port of the DUT/SUT and ending
the last bit of the output IP packet is seen on the output when the last bit of the output IP packet is received from
port of the DUT/SUT. the output port of the DUT/SUT.
Discussion: Discussion:
Delay differs from latency [Br91] and one-way delay [Al99] in The delay time interval MUST be externally observed. The
several key regards: delay measurement MUST NOT include delays added by test bed
components other than the DUT/SUT, such as propagation time
introduced by cabling or non-zero delay added by the test
instrument.
Forwarding Delay differs from latency [Br91] and one-way
delay [Al99] in several key regards:
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.
Delay is delay, regardless of the technology being measured. Forwarding Delay is the same metric, measured the same way,
regardless of the architecture of the DUT/SUT.
2. Delay is a last-in, last-out (LILO) measurement, unlike 2. Forwarding Delay is a last-in, last-out (LILO)
the last-in, first-out method [Br91] or the first-in, last- measurement, unlike the last-in, first-out method [Br91] or
out method [Al99]. the first-in, last-out method [Al99].
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. Delay measures the IP datagram only, unlike [Br91], which 3. Forwarding Delay measures the IP datagram only, unlike
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.
Network-layer Traffic Control Mechanisms 4. Forwarding Delay can be measured at any offered load,
whereas the latency methodology [Br99] recommends measurement
4. Delay can be measured at any offered load, whereas latency at, and only at, the throughput level. Comparing the
[Br99] is measured only at the throughput level. Forwarding Delay below the throughput to Forwarding Delay
above the channel capacity will give insight to the traffic
control mechanisms.
For example, non-congested delay may be measured with an For example, non-congested delay may be measured with an
offered load that does not exceed the channel capacity, while offered load that does not exceed the channel capacity, while
congested delay may involve an offered load that exceeds congested delay may involve an offered load that exceeds
channel capacity. channel capacity.
5. Delay SHOULD NOT be used as an absolute indicator of Note: Forwarding Delay SHOULD NOT be used as an absolute
DUT/SUT Forwarding Congestion. While delay may rise when indicator of DUT/SUT Forwarding Congestion. While Forwarding
offered load nears or exceeds channel capacity, there is no Delay may rise when offered load nears or exceeds channel
universal point at which delay can be said to indicate the capacity, there is no universal point at which Forwarding
presence or absence of Forwarding Congestion. Delay can be said to indicate the presence or absence of
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]
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 packets belonging to the same delay of two consecutive received packets belonging to the
stream. same stream.
Discussion: Discussion:
The delay fluctuation between two consecutive packets in a The delay fluctuation between two consecutive received
stream is reported as the jitter. Jitter can be expressed as packets in a stream is reported as the jitter. Jitter can be
|D(i) - D(i-1)| where D equals the delay and i is the test expressed as |D(i) - D(i-1)| where D equals the delay and i
sequence number. The measurement does not include lost is the order the packets were received.
packets.
Jitter can be determined by the ipdv [De02] (IP Delay Under loss, jitter can be measured between non-consecutive
Variation) by taking the absolute value of the ipdv. The two test sequence numbers. When Traffic Control Mechanisms are
metrics will produce different mean values. _Mean Jitter_ losing packets, the Forwarding Delay may fluctuate as a
will produce a positive value, where the _mean ipdv_ is Network-layer Traffic Control Mechanisms
typically zero.
response. Jitter MUST be able to benchmark the delay
variation with or with out loss.
Jitter is related to the ipdv [De02] (IP Delay Variation) by
taking the absolute value of the ipdv. The two metrics will
produce different mean values. _Mean Jitter_ will produce a
positive value, where the _mean ipdv_ is typically zero.
Measurement units: Measurement units:
Seconds Seconds
See Also: See Also:
Forwarding Delay
Jitter variation [Ja99] Jitter variation [Ja99]
ipdv [De02] ipdv [De02]
interarrival jitter [Sc96] interarrival jitter [Sc96]
Network-layer Traffic Control Mechanisms
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 may
skipping to change at page 11, line 38 skipping to change at page 12, line 4
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
Network-layer Traffic Control Mechanisms
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 that
expected. expected.
skipping to change at page 12, line 41 skipping to change at page 13, line 4
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
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:
Measurement units: Measurement units:
Packet count Packet count
Network-layer Traffic Control Mechanisms
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" (RFC 2889). Streams define how individual signature field" [Ma00]. Streams define how individual
packet's statistics are grouped together to form an packet's statistics 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 3.3.6 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.
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.
Network-layer Traffic Control Mechanisms
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
packets, number of out-sequence packets, number of duplicate packets, number of out-sequence packets, number of duplicate
packets, and number of reordered packets. packets, and number of reordered packets.
The recommended algorithm to use to change the sequence The recommended algorithm to use to change the sequence
number on sequential packets is an incrementing value. number on sequential packets is an incrementing value.
Measurement units: Measurement units:
skipping to change at page 14, line 32 skipping to change at page 14, line 45
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 rate at which packets having a
specific code-point (or IP precedence) that an external specific code-point (or IP precedence) that an external
source attempts to transmit to a DUT/SUT. source attempts to transmit to a DUT/SUT.
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
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
Network-layer Traffic Control Mechanisms
3.4.2 Offered Vector 3.4.2 Offered Vector
Definition: Definition:
A vector describing the measured rate at which packets having A vector describing the measured rate at which packets having
a specific DSCP or IP precedence value are offered to the a specific DSCP or IP precedence value are offered to the
DUT/SUT. DUT/SUT.
Discussion: Discussion:
Offered loads across the different code-point classes, Offered loads across the different code-point classes,
skipping to change at page 15, line 40 skipping to change at page 16, line 5
3.4.3 Expected Vectors 3.4.3 Expected Vectors
3.4.3.1 Expected Forwarding Vector 3.4.3.1 Expected Forwarding Vector
Definition: Definition:
A vector describing the expected output rate of packets A vector describing the expected output rate of 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.
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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
Network-layer Traffic Control Mechanisms
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 Delay Vector Expected Delay Vector
Expected Jitter Vector Expected Jitter Vector
skipping to change at page 16, line 29 skipping to change at page 16, line 45
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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 are expected to be
dropped. dropped.
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 3.2.3.3 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.
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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
skipping to change at page 17, line 38 skipping to change at page 18, line 5
Expected Delay Vector Expected Delay Vector
Expected Jitter Vector Expected Jitter Vector
3.4.3.4 Expected Instantaneous Delay Vector 3.4.3.4 Expected Instantaneous Delay Vector
Definition: Definition:
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
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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.
Network-layer Traffic Control Mechanisms
See Also: See Also:
Forwarding Delay
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
3.4.3.5 Expected Average Delay Vector 3.4.3.5 Expected Average Delay Vector
skipping to change at page 18, line 39 skipping to change at page 19, line 5
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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
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
3.4.3.6 Expected Maximum Delay Vector 3.4.3.6 Expected Maximum Delay Vector
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.
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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
skipping to change at page 19, line 39 skipping to change at page 20, line 5
Expected Jitter Vector Expected Jitter Vector
3.4.3.7 Expected Minimum Delay Vector 3.4.3.7 Expected Minimum Delay Vector
Definition: Definition:
A vector describing the expected minimum delay for packets A vector describing the expected minimum 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.
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 attempts
to capture the expected forwarding behavior when subjected to to capture the expected forwarding behavior when subjected to
a certain offered vectors. 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.
Network-layer Traffic Control Mechanisms
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 3.2.3.8 Expected Instantaneous Jitter Vector
skipping to change at page 20, line 41 skipping to change at page 21, line 4
Instantaneous Jitter can be expressed as |D(i) - D(i-1)| Instantaneous Jitter can be expressed as |D(i) - D(i-1)|
where D equals the delay and i is the test sequence number. where D equals the delay and i is the test sequence number.
Packets lost are not counted in the measurement. Packets lost are not counted in the measurement.
Forwarding Vector may contain several Jitter Vectors. For n Forwarding Vector may contain several Jitter Vectors. For n
packets received in a Forwarding Vector, there is a total of packets received in a Forwarding Vector, there is a total of
(n-1) Instantaneous Jitter Vectors. (n-1) Instantaneous Jitter Vectors.
Measurement units: Measurement units:
Seconds Seconds
Network-layer Traffic Control Mechanisms
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
Network-layer Traffic Control Mechanisms
3.2.3.9 Expected Average Jitter Vector 3.2.3.9 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 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:
skipping to change at page 21, line 44 skipping to change at page 22, line 4
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.
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
Network-layer Traffic Control Mechanisms
3.4.4 Output Vectors 3.4.4 Output Vectors
3.4.4.1 Forwarding Vector 3.4.4.1 Forwarding Vector
Definition: Definition:
The number of packets per second for all packets containing a The number of packets per second for all packets containing a
specific DSCP or IP precedence value that a device can be specific DSCP or IP precedence value that a device can be
observed to successfully forward to the correct destination observed to successfully forward to the correct destination
interface in response to an offered vector. interface in response to an offered vector.
skipping to change at page 22, line 41 skipping to change at page 23, line 4
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
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 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.
Network-layer Traffic Control Mechanisms
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.
skipping to change at page 23, line 42 skipping to change at page 24, line 5
The number of packets per second for all packets containing a The number of packets per second for all packets containing a
specific DSCP or IP precedence value that a device can be specific DSCP or IP precedence value that a device can be
observed to transmit in sequence to the correct destination observed to transmit in sequence to the correct destination
interface in response to an offered vector. interface in response to an offered vector.
Discussion: Discussion:
Sequence Vector is expressed as pair of numbers. Both the Sequence 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.
Network-layer Traffic Control Mechanisms
The Sequence Vector represents packet rate based on its The Sequence Vector represents packet rate based 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 Sequence Vector may be based on a stream or flow. The Sequence Vector may be
expressed as per port of the DUT/SUT. However, it must be expressed as per port of the DUT/SUT. However, it must be
consistent with the Expected Sequence Vector. consistent with the Expected Sequence Vector.
Sequence Vector is a per-hop measurement. The DUT/SUT may Sequence 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
Issues: Issues:
Network-layer Traffic Control Mechanisms
See Also: See Also:
In-sequence Packet In-sequence Packet
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
skipping to change at page 24, line 39 skipping to change at page 25, line 5
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 congestion. For congested delay, run the offered
load above the channel capacity. load above the channel capacity.
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
Network-layer Traffic Control Mechanisms
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 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:
skipping to change at page 25, line 37 skipping to change at page 26, line 5
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
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
Network-layer Traffic Control Mechanisms
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 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:
skipping to change at page 26, line 44 skipping to change at page 27, line 4
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
Forwarding Vector Forwarding Vector
Average Delay Vector Average Delay Vector
Minimum Delay Vector Minimum Delay Vector
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 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.
Network-layer Traffic Control Mechanisms
The Minimum Delay Vector represents delay on its specific The Minimum Delay Vector represents delay on its 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 Minimum Delay vector may be expressed a stream or flow. The Minimum 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 vector. with the Expected Delay vector.
Minimum Delay Vector is based upon the minimum Instantaneous Minimum Delay Vector is based upon the minimum Instantaneous
Delay Vector of all packets in a Forwarding Vector. Delay Vector of all packets in a Forwarding Vector.
Minimum Delay Vector is a per-hop measurement. The DUT/SUT Minimum Delay Vector is a per-hop measurement. The DUT/SUT
skipping to change at page 27, line 41 skipping to change at page 28, line 4
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:
Network-layer Traffic Control Mechanisms
The jitter for two consecutive packets containing specific 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.
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.
Network-layer Traffic Control Mechanisms
The delay fluctuation between two consecutive packets in a The delay fluctuation between two consecutive packets in a
stream is reported as the "Instantaneous Jitter". stream is reported as the "Instantaneous Jitter".
Instantaneous Jitter Vector can be expressed as |D(i) - D(i- Instantaneous Jitter Vector can be expressed as |D(i) - D(i-
1)| where D equals the delay and i is the test sequence 1)| where D equals the delay and i is the test sequence
number. Packets lost are not counted in the measurement. number. Packets lost are not counted in the measurement.
Instantaneous Jitter Vector is a per-hop measurement. The Instantaneous Jitter 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.
skipping to change at page 28, line 42 skipping to change at page 29, line 4
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 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:
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.
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
Network-layer Traffic Control Mechanisms
See Also: See Also:
Jitter Jitter
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
skipping to change at page 29, line 42 skipping to change at page 30, line 4
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. 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. Normative References 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
[Br91] Bradner, S., Editor, "Benchmarking Terminology for [Br91] Bradner, S., Editor, "Benchmarking Terminology for
Network Interconnection Devices", RFC 1242, July 1991. Network Interconnection Devices", RFC 1242, July 1991.
[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] K. Nichols, S. Blake, F. Baker, D. Black,"Definition of
the Differentiated Services Field (DS Field) in the IPv4 the Differentiated Services Field (DS Field) in the IPv4
and IPv6 Headers", RFC 2474, December 1998. and IPv6 Headers", RFC 2474, December 1998.
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
6. 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] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W.
Weiss, "An Architecture for Differentiated Services", Weiss, "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
skipping to change at page 31, line 31 skipping to change at page 32, line 31
[Ja99] V. Jacobson, K. Nichols, K. Poduri, _An Expedited [Ja99] V. Jacobson, K. Nichols, K. Poduri, _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] A. Mankin, K. Ramakrishnan, _Gateway Congestion Control
Survey_, RFC 1254, August 1991 Survey_, RFC 1254, August 1991
[Ma00] R. Mandeville, J. Perser, _Benchmarking Methodology for
LAN Switching Devices_, RFC 2889, August 2000
[Na84] Nagle, John, "Congestion Control in IP/TCP [Na84] Nagle, John, "Congestion Control in IP/TCP
Internetworks", RFC 896, January 1984. 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] H. Schulzrinne, GMD Fokus, S. Casner, R. Frederick,
V. Jacobson, _RTP: A Transport Protocol for Real-Time V. Jacobson, _RTP: A Transport Protocol for Real-Time
Applications_, RFC 1889, January 1996 Applications_, RFC 1889, January 1996
Network-layer Traffic Control Mechanisms Network-layer Traffic Control Mechanisms
7. Authors' Address 8. Authors' Address
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 6 skipping to change at page 34, line 6
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
8. Full Copyright Statement 9. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Copyright (C) The Internet Society (1998). 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
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/