draft-ietf-bmwg-dsmterm-03.txt | draft-ietf-bmwg-dsmterm-04.txt | |||
---|---|---|---|---|
Network Working Group Jerry Perser | Network Working Group Jerry Perser | |||
INTERNET-DRAFT Spirent | INTERNET-DRAFT Spirent | |||
Expires in: December 2002 David Newman | Expires in: April 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 | |||
June 2002 | October 2002 | |||
Terminology for Benchmarking Network-layer | Terminology for Benchmarking Network-layer | |||
Traffic Control Mechanisms | Traffic Control Mechanisms | |||
<draft-ietf-bmwg-dsmterm-03.txt> | <draft-ietf-bmwg-dsmterm-04.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 10 | skipping to change at page 2, line 10 | |||
3.1.3 Congestion .............................................4 | 3.1.3 Congestion .............................................4 | |||
3.1.4 Congestion Management ..................................5 | 3.1.4 Congestion Management ..................................5 | |||
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 .............................................7 | 3.2.2 Conforming .............................................7 | |||
3.2.3 Nonconforming ..........................................8 | 3.2.3 Nonconforming ..........................................8 | |||
3.2.4 Delay ..................................................8 | 3.2.4 Delay ..................................................8 | |||
3.2.6 Undifferentiated Response ................................9 | 3.2.5 Jitter .................................................9 | |||
3.2.6 Undifferentiated Response .............................10 | ||||
3.3 Sequence Tracking | 3.3 Sequence Tracking | |||
3.3.1 In-sequence Packet .....................................9 | 3.3.1 In-sequence Packet ....................................10 | |||
3.3.2 Out-of-order Packet ...................................10 | 3.3.2 Out-of-order Packet ...................................11 | |||
3.3.3 Duplicate Packet ......................................11 | 3.3.3 Duplicate Packet ......................................11 | |||
3.3.4 Stream ................................................11 | 3.3.4 Stream ................................................12 | |||
3.3.5 Test Sequence number .................................12 | 3.3.5 Test Sequence number .................................12 | |||
3.4 Vectors ...................................................12 | 3.4 Vectors ...................................................13 | |||
3.4.1 Intended Vector .......................................12 | 3.4.1 Intended Vector .......................................13 | |||
3.4.2 Offered Vector ........................................13 | 3.4.2 Offered Vector ........................................14 | |||
3.4.3 Expected Vectors | 3.4.3 Expected Vectors | |||
3.4.3.1 Expected Forwarding Vector ........................13 | 3.4.3.1 Expected Forwarding Vector ........................14 | |||
3.4.3.2 Expected Loss Vector ..............................14 | 3.4.3.2 Expected Loss Vector ..............................15 | |||
3.4.3.3 Expected Sequence Vector ..........................14 | 3.4.3.3 Expected Sequence Vector ..........................16 | |||
3.4.3.4 Expected Instantaneous Delay Vector ...............15 | 3.4.3.4 Expected Instantaneous Delay Vector ...............16 | |||
3.4.3.5 Expected Average Delay Vector .....................16 | 3.4.3.5 Expected Average Delay Vector .....................17 | |||
3.4.3.6 Expected Maximum Delay Vector .....................17 | 3.4.3.6 Expected Maximum Delay Vector .....................17 | |||
3.4.3.7 Expected Minimum Delay Vector .....................17 | 3.4.3.7 Expected Minimum Delay Vector .....................18 | |||
3.4.3.8 Expected Instantaneous Delay Variation Vector .....18 | 3.4.3.8 Expected Instantaneous Jitter Vector ..............19 | |||
3.4.3.9 Expected Average Delay Variation Vector ...........19 | 3.4.3.9 Expected Average Jitter Vector ....................19 | |||
3.4.3.10 Expected Peak-to-peak Delay Variation Vector .....19 | 3.4.3.10 Expected Peak-to-peak Jitter Vector ..............20 | |||
3.4.4 Output Vectors | 3.4.4 Output Vectors | |||
3.4.4.1 Forwarding Vector .................................20 | 3.4.4.1 Forwarding Vector .................................21 | |||
3.4.4.2 Loss Vector .......................................20 | 3.4.4.2 Loss Vector .......................................21 | |||
3.4.4.3 Sequence Vector ...................................21 | 3.4.4.3 Sequence Vector ...................................22 | |||
3.4.4.4 Instantaneous Delay Vector ........................22 | 3.4.4.4 Instantaneous Delay Vector ........................23 | |||
3.4.4.5 Average Delay Vector ..............................23 | 3.4.4.5 Average Delay Vector ..............................24 | |||
3.4.4.6 Maximum Delay Vector ..............................23 | 3.4.4.6 Maximum Delay Vector ..............................25 | |||
3.4.4.7 Minimum Delay Vector ..............................24 | 3.4.4.7 Minimum Delay Vector ..............................25 | |||
3.4.4.8 Instantaneous Delay Variation Vector ..............25 | 3.4.4.8 Instantaneous Jitter Vector .......................26 | |||
3.4.4.9 Average Delay Variation Vector ....................26 | 3.4.4.9 Average Jitter Vector .............................27 | |||
3.4.4.10 Peak-to-peak Delay Variation Vector ..............27 | 3.4.4.10 Peak-to-peak Jitter Vector .......................28 | |||
4. Security Considerations ....................................28 | 4. Security Considerations ....................................29 | |||
5. References .................................................28 | 5. References .................................................29 | |||
6. Author's Address ...........................................29 | 6. Author's Address ...........................................30 | |||
7. Full Copyright Statement ...................................30 | 7. Full Copyright Statement ...................................31 | |||
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- | |||
Network-layer Traffic Control Mechanisms | ||||
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. | |||
Network-layer Traffic Control Mechanisms | ||||
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 | |||
taken on ingress; without observing traffic leaving a | taken on ingress; without observing traffic leaving a | |||
device/system it is not possible to say whether traffic-control | device/system it is not possible to say whether traffic-control | |||
mechanisms effectively dealt with congestion. | mechanisms effectively dealt with congestion. | |||
The principal measurements introduced in this document are vectors | The principal measurements introduced in this document are vectors | |||
for rate, delay, and jitter, all of which can be observed with or | for rate, delay, and jitter, all of which can be observed with or | |||
skipping to change at page 3, line 53 | skipping to change at page 4, line 4 | |||
"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. | |||
3. Term definitions | 3. Term definitions | |||
3.1 Configuration Terms | 3.1 Configuration Terms | |||
3.1.1 Classification | 3.1.1 Classification | |||
Definition: | Definition: | |||
Selection of packets based on the contents of packet header | ||||
according to defined rules. | ||||
Network-layer Traffic Control Mechanisms | Network-layer Traffic Control Mechanisms | |||
Selection of packets based on the contents of packet header | ||||
according to defined rules. | ||||
Discussion: | Discussion: | |||
Packets can be selected based on the DS field or IP | Packets can be selected based on the DS field or IP | |||
Precedence in the packet header. Classification can also be | Precedence in the packet header. Classification can also be | |||
based on Multi-Field (MF) criteria such as IP Source and | based on Multi-Field (MF) criteria such as IP Source and | |||
destination addresses, protocol and port number. | destination addresses, protocol and port number. | |||
Classification determines the per-hop behaviors and traffic | Classification determines the per-hop behaviors and traffic | |||
conditioning functions such as shaping and dropping that are | conditioning functions such as shaping and dropping that are | |||
to be applied to the packet. | to be applied to the packet. | |||
skipping to change at page 4, line 50 | skipping to change at page 4, line 53 | |||
Measurement Units: | Measurement Units: | |||
n/a | n/a | |||
See Also: | See Also: | |||
3.1.3 Congestion | 3.1.3 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 at any given instant. | offered more packets than are forwarded. | |||
Discussion: | Discussion: | |||
This condition is a superset of the overload definition [2]. | ||||
The overload definition assumes the congestion is introduced | ||||
Network-layer Traffic Control Mechanisms | Network-layer Traffic Control Mechanisms | |||
This condition is a superset of the overload definition [2]. | ||||
The overload definition assumes the congestion is introduced | ||||
strictly by the tester on ingress of a DUT/SUT. That may or | strictly by the tester on ingress of a DUT/SUT. That may or | |||
may not be the case here. | may not be the case here. | |||
Another difference between congestion and overload occurs | Another difference between congestion and overload occurs | |||
when the SUT comprises multiple elements, in that congestion | when the SUT comprises multiple elements, in that congestion | |||
may occur at multiple points. Consider an SUT comprising | may occur at multiple points. Consider an SUT comprising | |||
multiple edge devices exchanging traffic with a single core | multiple edge devices exchanging traffic with a single core | |||
device. Depending on traffic patterns, the edge devices may | device. Depending on traffic patterns, the edge devices may | |||
induce congestion on multiple egress interfaces on the core | induce congestion on multiple egress interfaces on the core | |||
device. In contrast, overload [1] deals only with overload on | device. In contrast, overload [1] deals only with overload on | |||
ingress. | ingress. | |||
Throughput [1] defines the lower boundary of congestion. | ||||
Throughput is the maximum offered rate with no congestion. | ||||
At offered rates above throughput, the DUT/SUT is considered | ||||
congested. | ||||
Ingress observations alone are not sufficient to cover all | Ingress observations alone are not sufficient to cover all | |||
cases in which congestion may occur. A device with an | cases in which congestion may occur. A device with an | |||
infinite amount of memory could buffer an infinite amount of | infinite amount of memory could buffer an infinite amount of | |||
packets, and eventually forward all of them. However, these | packets, and eventually forward all of them. However, these | |||
packets may or may not be forwarded during the test duration. | packets may or may not be forwarded during the test duration. | |||
Even though ingress interfaces accept all packets without | Even though ingress interfaces accept all packets without | |||
loss, this hypothetical device may still be congested. | loss, this hypothetical device may still be congested. | |||
The definition presented here explicitly defines congestion | The definition presented here explicitly defines congestion | |||
as an event observable on egress interfaces. Regardless of | as an event observable on egress interfaces. Regardless of | |||
internal architecture, any device that cannot forward packets | internal architecture, any device that cannot forward packets | |||
on one or more egress interfaces is congested. | on one or more egress interfaces is congested. | |||
Measurement units: | Measurement units: | |||
n/a | none | |||
See Also: | See Also: | |||
Gateway Congestion Control Survey [8] | ||||
3.1.4 Congestion Management | 3.1.4 Congestion Management | |||
Definition: | Definition: | |||
An implementation of one or more per-hop-behaviors to avoid | An implementation of one or more per-hop-behaviors to avoid | |||
or minimize the condition of congestion. | or minimize the condition of congestion. | |||
Discussion: | Discussion: | |||
Congestion management may seek either to control congestion | Congestion management may seek either to control congestion | |||
or avoid it altogether. Such mechanisms classify packets | or avoid it altogether. Such mechanisms classify packets | |||
based upon IP Precedence or DSCP settings in a packet's IP | based upon IP Precedence or DSCP settings in a packet's IP | |||
header. | header. | |||
Network-layer Traffic Control Mechanisms | ||||
Congestion avoidance mechanisms seek to prevent congestion | Congestion avoidance mechanisms seek to prevent congestion | |||
before it actually occurs. | before it actually occurs. | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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: | Discussion: | |||
skipping to change at page 7, line 47 | skipping to change at page 8, line 4 | |||
3.2.2 Conforming | 3.2.2 Conforming | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
Forwarding Vector | Forwarding Vector | |||
Offered Vector | Offered Vector | |||
Nonconforming | Nonconforming | |||
3.2.3 Nonconforming | 3.2.3 Nonconforming | |||
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. | |||
skipping to change at page 8, line 47 | skipping to change at page 9, line 5 | |||
the last bit of the output IP packet is seen on the output | the last bit of the output IP packet is seen on the output | |||
port of the DUT/SUT. | port of the DUT/SUT. | |||
Discussion: | Discussion: | |||
Delay is measured the same regardless of the type of DUT/SUT. | Delay is measured the same regardless of the type of DUT/SUT. | |||
Latency [1] require some knowledge of whether the DUT/SUT is | Latency [1] require some knowledge of whether the DUT/SUT is | |||
a "store and forward" or a "bit forwarding" device. The fact | a "store and forward" or a "bit forwarding" device. The fact | |||
that a DUT/SUT's technology has a lower delay than another | that a DUT/SUT's technology has a lower delay than another | |||
technology should be visible. | technology should be visible. | |||
Network-layer Traffic Control Mechanisms | ||||
By specifying the metric to be inside the Internet protocol, | By specifying the metric to be inside the Internet protocol, | |||
the tester is relieved from specifying the start/end for | the tester is relieved from specifying the start/end for | |||
every data link layer protocol that IP runs on. This avoids | every data link layer protocol that IP runs on. This avoids | |||
determining if the start/end delimiters are included in the | determining if the start/end delimiters are included in the | |||
frame. Also heterogeneous data link protocol can be used in | frame. Also heterogeneous data link protocol can be used in | |||
a test. | a test. | |||
The measurement point at the end closely simulates the way an | The measurement point at the end closely simulates the way an | |||
internet datagram is processed. An internet datagram is not | internet datagram is processed. An internet datagram is not | |||
Network-layer Traffic Control Mechanisms | ||||
passed up or down the stack unless it is complete. | passed up or down the stack unless it is complete. | |||
Completion occurs once the last bit of the IP packet has been | Completion occurs once the last bit of the IP packet has been | |||
received. | received. | |||
Delay can be run at any offered load. Recommend at or below | Delay can be run at any offered load. Recommend at or below | |||
the channel capacity for non-congested delay. For congested | the channel capacity for non-congested delay. For congested | |||
delay, run the offered load above the channel capacity. | delay, run the offered load above the channel capacity. | |||
Measurement units: | Measurement units: | |||
Seconds. | Seconds. | |||
See Also: | See Also: | |||
Latency [1] | Latency [1] | |||
3.2.5 Jitter | ||||
Definition: | ||||
The absolute value of the difference between the arrival | ||||
delay of two consecutive packets belonging to the same | ||||
stream. | ||||
Discussion: | ||||
The delay fluctuation between two consecutive 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 is the test | ||||
sequence number. The measurement does not include lost | ||||
packets. | ||||
Jitter can be determined by the ipdv [6] (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: | ||||
Seconds | ||||
See Also: | ||||
Jitter variation [5] | ||||
ipdv [6] | ||||
interarrival jitter [7] | ||||
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 | |||
degrade performance even when traffic belonging to only one | degrade performance even when traffic belonging to only one | |||
skipping to change at page 10, line 5 | skipping to change at page 10, line 41 | |||
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 | |||
compared with the previous packet. Only packets that match | compared with the previous packet. Only packets that match | |||
the expected are considered in-sequence. | the expected are considered in-sequence. | |||
Network-layer Traffic Control Mechanisms | ||||
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 11, line 4 | skipping to change at page 11, line 43 | |||
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: | |||
Stream | Stream | |||
Test Sequence number | Test Sequence number | |||
Network-layer Traffic Control Mechanisms | ||||
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 | |||
skipping to change at page 12, line 4 | skipping to change at page 12, line 40 | |||
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 [3] | MicroFlow [3] | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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 | |||
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 | |||
skipping to change at page 13, line 5 | skipping to change at page 13, line 44 | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
Loss Vector | Loss Vector | |||
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: | |||
skipping to change at page 14, line 4 | skipping to change at page 14, line 43 | |||
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. | |||
Discussion: | Discussion: | |||
Network-layer Traffic Control Mechanisms | ||||
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 15, line 4 | skipping to change at page 15, line 43 | |||
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. | |||
See Also: | See Also: | |||
Intended Vector | Intended Vector | |||
Offered Vector | Offered Vector | |||
Expected Forwarding Vector | Expected Forwarding Vector | |||
Network-layer Traffic Control Mechanisms | ||||
Expected Sequence Vector | Expected Sequence Vector | |||
Expected Delay Vector | Expected Delay Vector | |||
Expected Jitter Vector | Expected Jitter Vector | |||
3.2.3.3 Expected Sequence Vector | 3.2.3.3 Expected Sequence Vector | |||
Definition: | Definition: | |||
Network-layer Traffic Control Mechanisms | ||||
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 attempts | |||
to capture the expected forwarding behavior when subjected to | to capture the expected forwarding behavior when subjected to | |||
skipping to change at page 16, line 5 | skipping to change at page 16, line 50 | |||
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 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. | |||
Network-layer Traffic Control Mechanisms | ||||
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: | |||
Network-layer Traffic Control Mechanisms | ||||
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 17, line 4 | skipping to change at page 17, line 46 | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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. | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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 maximum delay vector. | expected maximum delay vector. | |||
Measurement units: | Measurement units: | |||
skipping to change at page 18, line 5 | skipping to change at page 18, line 47 | |||
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. | |||
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 Loss Vector | Expected Loss Vector | |||
Expected Sequence Vector | Expected Sequence Vector | |||
Expected Forwarding Vector | Expected Forwarding Vector | |||
Network-layer Traffic Control Mechanisms | ||||
Expected Jitter Vector | Expected Jitter Vector | |||
3.2.3.8 Expected Instantaneous Delay Variation Vector | 3.2.3.8 Expected Instantaneous Jitter Vector | |||
Definition: | Definition: | |||
A vector describing the expected variation in the delay of | A vector describing the expected jitter between two | |||
two consecutive packets' arrival times having a specific DSCP | consecutive packets' arrival times having a specific DSCP or | |||
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 Delay Variation is the absolute value of the | Instantaneous Jitter is the absolute value of the difference | |||
difference between the delay measurement of two packets | between the delay measurement of two packets belonging to the | |||
belonging to the same stream. | same stream. | |||
The delay fluctuation between two consecutive packets in a | The delay fluctuation between two consecutive packets in a | |||
stream is reported as the "Instantaneous Delay Variation". | stream is reported as the "Instantaneous Jitter". | |||
Instantaneous Delay Variation can be expressed as |D(i) - | Instantaneous Jitter can be expressed as |D(i) - D(i-1)| | |||
D(i-1)| where D equals the delay and i is the test sequence | where D equals the delay and i is the test sequence number. | |||
number. Packets lost are not counted in the measurement. | Packets lost are not counted in the measurement. | |||
Forwarding Vector may contain several Instantaneous Delay | Forwarding Vector may contain several Jitter Vectors. For n | |||
Variation Vectors. For n packets received in a Forwarding | packets received in a Forwarding Vector, there is a total of | |||
Vector, there is n-1 several Instantaneous Delay Variation | (n-1) Instantaneous Jitter Vectors. | |||
Vectors. | ||||
Measurement units: | Measurement units: | |||
Seconds | Seconds | |||
See Also: | See Also: | |||
Delay | Delay | |||
Jitter | ||||
Offered Vector | Offered Vector | |||
Output Vectors | Output Vectors | |||
Expected Average Delay Variation Vector | Expected Average Jitter Vector | |||
Expected Peak-to-peak Delay Variation Vector | Expected Peak-to-peak Jitter Vector | |||
Stream | Stream | |||
Network-layer Traffic Control Mechanisms | ||||
3.2.3.9 Expected Average Delay Variation Vector | 3.2.3.9 Expected Average Jitter Vector | |||
Definition: | Definition: | |||
A vector describing the expected average variation in the | A vector describing the expected jitter in packet arrival | |||
delay of packet arrival times for packets having specific | times for packets having specific DSCP or IP precedence | |||
DSCP or IP precedence value. The value is dependent on the | value. The value is dependent on the set of offered vectors | |||
set of offered vectors and configuration of the DUT. | and configuration of the DUT. | |||
Discussion: | Discussion: | |||
Average Delay Variation is the average of all the | Average Jitter Vector is the average of all the Instantaneous | |||
Instantaneous Delay Variation Vectors measured during the | Jitter Vectors measured during the test duration for the same | |||
test duration. | DSCP or IP precedence value. | |||
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 Delay Variation Vector | Expected Instantaneous Jitter Vector | |||
Expected Peak-to-peak Delay Variation Vector | Expected Peak-to-peak Jitter Vector | |||
3.2.3.10 Expected Peak-to-peak Delay Variation Vector | 3.2.3.10 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 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 Delay Variation Vector is the maximum delay | Peak-to-peak Jitter Vector is the maximum delay minus the | |||
minus the minimum delay of the packets (in a vector) | minimum delay of the packets (in a vector) forwarded by the | |||
forwarded by the DUT/SUT. | DUT/SUT. | |||
Peak-to-peak Delay Variation is not derived from the | Peak-to-peak Jitter is not derived from the Instantaneous | |||
Instantaneous Delay Variation Vector. Peak-to-peak Delay | Jitter Vector. Peak-to-peak Jitter is based upon all the | |||
Variation is based upon all the packets during the test | packets during the test duration, not just two consecutive | |||
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 Delay Variation Vector | Expected Instantaneous Jitter Vector | |||
Expected Average Delay Variation 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 | |||
Network-layer Traffic Control Mechanisms | ||||
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. | |||
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 | |||
skipping to change at page 21, line 5 | skipping to change at page 21, line 51 | |||
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 | |||
Network-layer Traffic Control Mechanisms | ||||
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 are not forwarded. | |||
See Also: | See Also: | |||
Intended Vector | Intended Vector | |||
skipping to change at page 22, line 4 | skipping to change at page 22, line 51 | |||
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: | |||
See Also: | See Also: | |||
In-sequence Packet | In-sequence Packet | |||
Network-layer Traffic Control Mechanisms | ||||
Intended Vector | Intended Vector | |||
Offered Vector | Offered Vector | |||
Expected Vectors | Expected Vectors | |||
Loss Vector | Loss Vector | |||
Forwarding Vector | Forwarding Vector | |||
Network-layer Traffic Control Mechanisms | ||||
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 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. | |||
skipping to change at page 23, line 4 | skipping to change at page 23, line 51 | |||
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: | |||
Network-layer Traffic Control Mechanisms | ||||
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: | |||
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. | |||
skipping to change at page 24, line 5 | skipping to change at page 24, line 55 | |||
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 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: | ||||
Network-layer Traffic Control Mechanisms | Network-layer Traffic Control Mechanisms | |||
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 | |||
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 Maximum Delay vector may be expressed | a stream or flow. The Maximum 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. | |||
skipping to change at page 25, line 5 | skipping to change at page 25, line 56 | |||
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 | |||
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. | |||
Network-layer Traffic Control Mechanisms | ||||
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. | |||
Network-layer Traffic Control Mechanisms | ||||
Minimum Delay Vector is a per-hop measurement. The DUT/SUT | Minimum 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. | |||
Minimum Delay vector can be obtained at any offered load. | Minimum 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. | |||
Measurement Units: | Measurement Units: | |||
skipping to change at page 25, line 32 | skipping to change at page 26, line 29 | |||
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 | |||
Maximum Delay Vector | Maximum Delay Vector | |||
3.4.4.8 Instantaneous Delay Variation Vector | 3.4.4.8 Instantaneous Jitter Vector | |||
Definition: | Definition: | |||
The variation in the delay for two consecutive packets | The jitter for two consecutive packets containing specific | |||
containing specific DSCP or IP precedence value that a device | DSCP or IP precedence value that a device can be observed to | |||
can be observed to successfully transmit to the correct | successfully transmit to the correct destination interface in | |||
destination interface in response to an offered vector. | response to an offered vector. | |||
Discussion: | Discussion: | |||
Instantaneous Delay Variation is the absolute value of the | Instantaneous Jitter is the absolute value of the difference | |||
difference between the delay measurement of two packets | between the delay measurement of two packets belonging to the | |||
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 | |||
stream is reported as the "Instantaneous Delay Variation". | stream is reported as the "Instantaneous Jitter". | |||
Instantaneous Delay Variation can be expressed as |D(i) - | Instantaneous Jitter Vector can be expressed as |D(i) - 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. | |||
Network-layer Traffic Control Mechanisms | Instantaneous Jitter Vector is a per-hop measurement. The | |||
DUT/SUT may change the specific DSCP or IP precedence value | ||||
for a multiple-hop measurement. | ||||
Instantaneous Delay Variation Vector is a per-hop | Network-layer Traffic Control Mechanisms | |||
measurement. The DUT/SUT may change the specific DSCP or IP | ||||
precedence value for a multiple-hop measurement. | ||||
Forwarding Vector may contain several Instantaneous Delay | Forwarding Vector may contain several Instantaneous Jitter | |||
Variation Vectors. For n packets received in a Forwarding | Vectors. For n packets received in a Forwarding Vector, | |||
Vector, there is n-1 several Instantaneous Delay Variation | there are exactly (n-1) Instantaneous Jitter Vectors. | |||
Vectors. | ||||
Measurement units: | Measurement units: | |||
Seconds | Seconds | |||
See Also: | See Also: | |||
Delay | Delay | |||
Jitter | ||||
Forwarding Vector | Forwarding Vector | |||
Stream | Stream | |||
Expected Vectors | Expected Vectors | |||
Average Delay Variation Vector | Average Jitter Vector | |||
Peak-to-peak Delay Variation Vector | Peak-to-peak Jitter Vector | |||
3.4.4.9 Average Delay Variation Vector | 3.4.4.9 Average Jitter Vector | |||
Definition: | Definition: | |||
The average variation in the delay for packets containing | The average jitter for packets containing specific DSCP or IP | |||
specific DSCP or IP precedence value that a device can be | precedence value that a device can be observed to | |||
observed to successfully transmit to the correct destination | successfully transmit to the correct destination interface in | |||
interface in response to an offered vector. | response to an offered vector. | |||
Discussion: | Discussion: | |||
Average Delay Variation is the average of all the | Average Jitter Vector is the average of all the Instantaneous | |||
Instantaneous Delay Variation Vectors measured during the | Jitter Vectors of the same DSCP or IP precedence value, | |||
test duration. | measured during the test duration. | |||
Average Delay Variation vector is expressed as pair of | Average Jitter vector is expressed as pair of numbers. Both | |||
numbers. Both the specific DSCP (or IP precedence) value AND | the specific DSCP (or IP precedence) value AND jitter value | |||
jitter value combine to make a vector. | combine to make a vector. | |||
Average Delay Variation vector is a per-hop measurement. The | Average Jitter vector is a per-hop measurement. The DUT/SUT | |||
DUT/SUT may change the specific DSCP or IP precedence value | may change the specific DSCP or IP precedence value for a | |||
for a multiple-hop measurement. | multiple-hop measurement. | |||
Measurement units: | Measurement units: | |||
Seconds | Seconds | |||
See Also: | See Also: | |||
Delay | Jitter | |||
Forwarding Vector | Forwarding Vector | |||
Stream | Stream | |||
Expected Vectors | Expected Vectors | |||
Instantaneous Delay Variation Vector | Instantaneous Jitter Vector | |||
Peak-to-peak Delay Variation Vector | Peak-to-peak Jitter Vector | |||
Network-layer Traffic Control Mechanisms | ||||
3.4.4.10 Peak-to-peak Delay Variation Vector | 3.4.4.10 Peak-to-peak Jitter Vector | |||
Network-layer Traffic Control Mechanisms | ||||
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 specific DSCP or IP precedence value that a device | |||
can be observed to successfully transmit to the correct | can be observed to successfully transmit to the correct | |||
destination interface in response to an offered vector. | destination interface in response to an offered vector. | |||
Discussion: | Discussion: | |||
Peak-to-peak Delay Variation Vector is the maximum delay | Peak-to-peak Jitter Vector is the maximum delay minus the | |||
minus the minimum delay of the packets (in a vector) | minimum delay of the packets (in a vector) forwarded by the | |||
forwarded by the DUT/SUT. | DUT/SUT. | |||
Delay Variation vector is expressed as pair of numbers. Both | Jitter vector is expressed as pair of numbers. Both the | |||
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. | |||
Peak-to-peak Delay Variation is not derived from the | Peak-to-peak Jitter is not derived from the Instantaneous | |||
Instantaneous Delay Variation Vector. Peak-to-peak Delay | Jitter Vector. Peak-to-peak Jitter is based upon all the | |||
Variation is based upon all the packets during the test | packets during the test duration, not just two consecutive | |||
duration, not just two consecutive packets. | packets. | |||
Measurement units: | Measurement units: | |||
Seconds | Seconds | |||
See Also: | See Also: | |||
Delay | Jitter | |||
Forwarding Vector | Forwarding Vector | |||
Stream | Stream | |||
Expected Vectors | Expected Vectors | |||
Average Delay Variation Vector | Average Jitter Vector | |||
Peak-to-peak Delay Variation 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 | |||
skipping to change at page 29, line 5 | skipping to change at page 29, line 34 | |||
Switching Devices", RFC 2285, February 1998. | Switching Devices", RFC 2285, February 1998. | |||
[3] K. Nichols, S. Blake, F. Baker, D. Black,"Definition of | [3] 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. | |||
[4] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. | [4] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. | |||
Weiss, "An Architecture for Differentiated Services", RFC | Weiss, "An Architecture for Differentiated Services", RFC | |||
2475, December 1998. | 2475, December 1998. | |||
[5] V. Jacobson, K. Nichols, K. Poduri, _An Expedited | ||||
Forwarding PHB_, RFC 2598, June 1999 | ||||
[6] C. Demichelis, P. Chimento, _IP Packet Delay Variation | ||||
Metric for IPPM_, draft-ietf-ippm-ipdv-10.txt | ||||
[7] H. Schulzrinne, GMD Fokus, S. Casner, R. Frederick, | ||||
V. Jacobson, _RTP: A Transport Protocol for Real-Time | ||||
Applications_, RFC 1889, January 1996 | ||||
[8] A. Mankin, K. Ramakrishnan, _Gateway Congestion Control | ||||
Survey_, RFC 1254, August 1991 | ||||
Network-layer Traffic Control Mechanisms | Network-layer Traffic Control Mechanisms | |||
6. Authors' Address | 6. Authors' Address | |||
Jerry Perser | Jerry Perser | |||
Spirent Communications | Spirent Communications | |||
26750 Agoura Road | 26750 Agoura Road | |||
Calabasas, CA 91302 | Calabasas, CA 91302 | |||
USA | USA | |||
End of changes. | ||||
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