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WO2001091375A2 - Procede et systeme de mesure de variation de retard unidirectionnelle - Google Patents

Procede et systeme de mesure de variation de retard unidirectionnelle Download PDF

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Publication number
WO2001091375A2
WO2001091375A2 PCT/US2001/015741 US0115741W WO0191375A2 WO 2001091375 A2 WO2001091375 A2 WO 2001091375A2 US 0115741 W US0115741 W US 0115741W WO 0191375 A2 WO0191375 A2 WO 0191375A2
Authority
WO
WIPO (PCT)
Prior art keywords
time
delay variation
network
packet
packets
Prior art date
Application number
PCT/US2001/015741
Other languages
English (en)
Other versions
WO2001091375A3 (fr
Inventor
Michael Brown
Original Assignee
Williams Communications Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Williams Communications Llc filed Critical Williams Communications Llc
Priority to AU2001263161A priority Critical patent/AU2001263161A1/en
Priority to MXPA02011438A priority patent/MXPA02011438A/es
Priority to CA002409001A priority patent/CA2409001A1/fr
Priority to EP01937419A priority patent/EP1282956A2/fr
Priority to JP2001586844A priority patent/JP2003534715A/ja
Publication of WO2001091375A2 publication Critical patent/WO2001091375A2/fr
Publication of WO2001091375A3 publication Critical patent/WO2001091375A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0852—Delays
    • H04L43/087—Jitter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/12—Network monitoring probes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0852—Delays
    • H04L43/0858—One way delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/10—Active monitoring, e.g. heartbeat, ping or trace-route
    • H04L43/106—Active monitoring, e.g. heartbeat, ping or trace-route using time related information in packets, e.g. by adding timestamps

Definitions

  • the present invention relates generally to network performance measurement, and more particularly, to measuring the one-way delay variation in a network using a non-uniform data transmission rate.
  • An important feature in an Internet network capable of providing quality of service guarantees to customers is the ability to prove that the promised quality of service is being met, by measuring actual network performance.
  • One measure of network performance is the latency, or delay, measurement, which measures how much time it takes for a packet to get from one point to another on a network.
  • a related measure of performance is the delay variation, which measures the rate of change in the latency measurement. Jitter is the amount that the transmission rate actually varies from the mean during a current time period. Jitter is a critical parameter that affects the quality of network transmissions that are highly delay- sensitive, such as audio and video transmissions.
  • Network delay can be measured either for a packet round-trip, or in a single direction.
  • the round-trip delay time may be measured using both sending and receiving equipment in the same location, and is therefore convenient to measure.
  • One existing method involves measuring the round-trip delay time by using a network "ping" feature. Ping is a common network debugging tool that places a timestamp in each packet, which is echoed back and can be used to compute the time required for each round trip packet exchange.
  • the round trip delay variation time may not accurately reflect individual one-way delay variation.
  • the sending and receiving paths may not be symmetrical, and therefore differences will exist between the sending and receiving direction delay variations. More precise measurements of individual paths will be achieved by measuring one-way delay variation.
  • One existing method for measuring one-way delay variation relies on an absolute clock to synchronize the time between two different monitoring points on the network.
  • an absolute clock such as a Global Positioning System (GPS) time receiver
  • GPS Global Positioning System
  • the ability to measure the one-way delay without an absolute clock will allow the one-way delay variation measurement to be much more widely deployed than at present.
  • An additional existing method of measuring delay variation relies on sending packets across a network at a known, pre-determined rate. Given this known sending rate, variations from the known rate can be measured.
  • a more flexible method for measuring oneway delay variation is desirable, which would allow the granularity of measurements to change as network performance changes.
  • the present invention allows the one-way delay variation across a network to be measured in a flexible manner. No absolute clock is required to perform the measurements. Additionally, packets used for measurement are sent at a non-uniform rate, wherein the rate used is adjusted based upon operational parameters. For example, the measurement frequency rate may be increased when the one-way delay variation is changing most rapidly. This allows for increased measurement granularity when network conditions appear to be fluctuating. Additionally, the non-uniform sending rate allows a system administrator to vary the bandwidth put on the system by one-way delay variation measurements. This ability to vary bandwidth is desirable, for example, if existing network bandwidth is currently overloaded, because the system administrator can decrease the delay variation measuring rate to avoid further bandwidth stress.
  • a transmitter on a network transmits probe packets with a transmission time indication
  • a receiver on the network receives a first probe packet and a second probe packet.
  • the one-way delay variation between the two probe packets is calculated.
  • the delay variation is equal to the difference in arrival time between the first and second probe packets minus the difference in the transmission time indication between the first and second probe packets.
  • Fig. 1 A is a diagram of a network system illustrating the use of a transmitter and a receiver to measure network delay parameters in an embodiment of the present invention.
  • Fig. IB is a diagram of a probe packet used in measuring one-way delay variation in an embodiment of the present invention.
  • Fig. 2 is a flowchart of a method for sending packets for measuring one-way delay variation in an embodiment of the present invention.
  • Fig. 3 is a flowchart of a method for receiving packets and calculating the one-way delay variation in a network in an embodiment of the present invention.
  • a network system includes a monitoring system to measure the one-way delay variation between different points in the network.
  • the one-way delay variation is the change in the network delay, or latency, over time.
  • Network latency is the time it takes for a signal to travel between different points on the network.
  • One embodiment of a signal is an Internet Protocol (IP) packet.
  • IP Internet Protocol
  • the one-way delay variation of a network path is calculated based on the sending and arrival times of packets traveling the network path.
  • the arrival time A of a packet is equal to the sending, or transmission time Eplus the network delay D:
  • the absolute value of the network delay D cannot be measured accurately as the difference between A measured at the arrival clock and T measured at the transmission clock.
  • the delay variation in the network may be accurately calculated by comparing differences in arrival and transmission times between two separate packets sent on the network.
  • the network delay D is equal to a fixed network delay Df ⁇ x plus the network delay variation D var that occurred during transmission of the particular packet at issue:
  • the fixed delay D ⁇ x is assumed to be constant for all packets traveling on the same network path or route. This fixed delay is composed of the propagation delays and the minimum processing time of each piece of switching and transmission equipment.
  • the delay variation D var is the portion of the delay D that varies during the transmission of different packets. This variable delay is created by a variety of factors, including queuing delays and variations in the processing time of each piece of switching and transmission equipment.
  • the arrival time difference between two separate packets (i) and (t+1) will equal the transmission time difference between the two packets plus the delay time difference between the two packets:
  • a ⁇ i) - A(i + 1) [T( ⁇ ) - T(i + 1)] + [D(i) - D(i + 1)] (3)
  • AD D v r (i)-D va ⁇ (i+ ⁇ ) (6) Therefore the one-way delay variation for a network path is calculated as:
  • the method of equation 7 is implemented in a network monitoring system to measure delay variation in one or more routes of a network (or networks).
  • the network monitoring system includes a transmitter and a receiver capable of sending packets between themselves.
  • a single transmitter is adapted to transmit signals to a plurality of receivers, using, for example, a multicast IP packet type.
  • a first number of transmitters is smaller than a second number of receivers.
  • a first number of transmitters is greater than a second number of receivers.
  • FIG. 1 A is an illustration of an embodiment of a network system for measuring oneway delay variation.
  • a network 101 includes a set of routers 120A-G and a transmitter 100.
  • a network 102 includes a set of routers 130A-D and a receiver 110.
  • Networks 101 and 102 are interconnected at a set of connections 140A, 140B and 140C.
  • Transmitter 100 sends probe packets to receiver 110 via a route 180, which includes routers 120E, 130C and 130D. The probe packets are used to measure the one-way delay variation on route 180 between transmitter 100 and receiver 110.
  • Fig. 1A additionally illustrates why measuring the round-trip delay and delay variation is not equivalent to doubling the one-way delay variation.
  • a return route 190 is used to route packets from receiver 110 to transmitter 100.
  • a round-trip delay measurement would combine measurements of the delay on route 180 and route 190.
  • the round-trip delay variation is not specific to route 180.
  • Fig. IB illustrates an embodiment of a probe packet suitable for use in measuring the one-way delay variation on a network.
  • a probe packet 10 includes a sequence number 12 and a transmission time 14. Successive probe packets are given successive sequence numbers.
  • the transmission time 14 is implemented as a time stamp in one embodiment. It will be evident to one of skill in the art that different types of probe packets may be used for measuring the one-way delay variation in a network. For example, in one embodiment, the information included in the probe packet may be appended to normal data-carrying packets traveling between the transmitter and receiver locations.
  • the transmitter and the receiver are both computers connected to the network and adapted to perform the transmitter or receiver functions.
  • the functionality of the transmitter is embedded in an application specific integrated circuit (ASIC), and the functionality of the receiver is embedded in a separate ASIC.
  • the transmitter and receiver are software modules adapted to perform the transmitter or receiver functions.
  • Fig. 2 is a flowchart of the functions performed by the transmitter.
  • the transmitter initializes 210 a sequence of probe packets by setting the sequence number equal to /.
  • the transmitter then sends 220 a probe packet with a transmission time indication and a sequence number.
  • the transmission time indication is a timestamp, which indicates the current time at the transmitter.
  • the transmitter waits 230 for a period of time INTERVAL, and then increments 240 the sequence number by one and returns to step 220 to send another probe packet.
  • sequence numbers do not have to be increased by an integer amount. It will be evident to one of skill in the art that the sequence numbers may be set to increase in any logical sequence, as long as the receiver is able to distinguish between sequential versus nonsequential probe packets.
  • the INTERVAL time period may be set by a system user and may be changed as desired during the probe packet transmitting process. For example, in one embodiment a typical INTERVAL time is five seconds. However, if the system user notes that the one-way delay variation measurements appear to be changing rapidly, the INTERVAL time may be decreased to increase the granularity of measurement for the one-way delay variation. Additionally, if the system user notes that network traffic appears to be approaching network bandwidth limitations, the system user may increase the INTERVAL time in order to decrease the amount of bandwidth added to the network by the probe packets. In one embodiment, the transmitter automatically varies the INTERVAL time parameter in response to changes in the one-way delay variation measurements or changes in network bandwidth.
  • Fig. 3 is a flowchart of the functions performed by a receiver.
  • the receiver waits 310 to receive a probe packet 305.
  • the receiver stores 320 the time probe packet 305 arrived T(t), and stores the sequence number of probe packet 305 as the last sequence number SEQ(t).
  • the receiver then waits 330 to receive a next probe packet 325 with a sequence number SEQ(t+l). Upon receipt of next probe packet 325, the receiver checks 340 to determine if probe packets 305 and 325 are sequential. Assuming monotomcally increasing sequence numbers:
  • the receiver returns to step 320 and stores the sequence number and arrival time for probe packet 325 as SEQ(z ' ) and T(t), respectively.
  • the receiver will not calculate the one-way delay variation on probe packets that are not sequential. Non-sequential packets indicate that probe packets have been lost, and the system will note this problem. It will be evident to one of skill in the art that if the possible loss of probe packets is not a concern, the timestamping procedure allows the one-way delay variation measurement to proceed using non-sequential packets.
  • the current one-way delay variation is calculated 350 as the difference between the two packets' arrival times minus the difference between the two packets' timestamp times (representing the two packets' transmission times).
  • the one-way delay variation may be positive or negative, indicating that the network one-way delay for the measured path is either increasing or decreasing, respectively.
  • the receiver then returns to waiting 310 for the next probe packet.
  • the receiver stores successive one-way delay variation measurements. Periodically, the receiver transfers the stored measurements back to a central data collection system.
  • the data collection system compiles statistics from multiple receivers, and prepares a statistical summary of one-way delay variation times throughout the network. The statistical summary provides msight into the workings of the network. For example, areas of the network experiencing wide fluctuations in delay variation are identified. The effect of available network bandwidth increases and decreases will also be identified by variations in the one-way delay variation measurement in addition to queuing changes on the transmission and switching equipment.
  • the accuracy of the one-way delay variation measurements is dependent on the INTERVAL time and the stability of the transmitter and receiver internal clocks. Both the transmitter and the receiver contain internal clocks for noting the time at which a signal is sent and received, respectively.
  • the transmitter and the receiver need only possess reasonable internal stability, which is achieved by the types of clocks found on existing computers.
  • a Pentium personal computer has an internal clock that is stable to at least 10 seconds/day, or approximately 1 part in 10,000. Assuming that the clock drift is uniform, an INTERVAL time between sending probe packets of 10 seconds allows the one- way delay variation to be measured to within one millisecond. If measurements with a longer INTERVAL time or a greater precision are desired, the internal clock stability of the transmitter and receiver is increased.
  • the invention has been described in considerable detail with reference to certain embodiments, other embodiments are possible.
  • the invention may be embodied in other specific forms without departing from the essential characteristics thereof.
  • the transmitter and the receiver may be implemented as hardware or software modules.
  • different numbers of transmitters and receivers may be combined to perform multiple simultaneous one-way delay variation measurements on different network routes. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims and equivalents.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Environmental & Geological Engineering (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

L'invention concerne un procédé et un système de mesure de variation de retard unidirectionnelle dans un réseau, permettant de transmettre des paquets d'essai avec un indicateur de temps de transmission et un numéro de séquence. Le réseau reçoit un premier paquet d'essai et un second paquet d'essai et note leurs heures d'arrivée. Si les paquets d'essai sont séquentiels, la variation du retard unidirectionnelle est calculée entre les deux paquets d'essai. La variation du retard est égale à la différence entre le temps d'arrivée des deux paquets d'essai à laquelle on soustrait la différence entre le temps de transmission du premier et du deuxième paquet d'essai.
PCT/US2001/015741 2000-05-19 2001-05-15 Procede et systeme de mesure de variation de retard unidirectionnelle WO2001091375A2 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
AU2001263161A AU2001263161A1 (en) 2000-05-19 2001-05-15 Method and system for measuring one-way delay variation
MXPA02011438A MXPA02011438A (es) 2000-05-19 2001-05-15 Metodo y sistema para medir una variacion de retraso de una via.
CA002409001A CA2409001A1 (fr) 2000-05-19 2001-05-15 Procede et systeme de mesure de variation de retard unidirectionnelle
EP01937419A EP1282956A2 (fr) 2000-05-19 2001-05-15 Procede et systeme de mesure de variation de retard unidirectionnelle
JP2001586844A JP2003534715A (ja) 2000-05-19 2001-05-15 一方向遅延変動を測定するための方法およびシステム

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57430700A 2000-05-19 2000-05-19
US09/574,307 2000-05-19

Publications (2)

Publication Number Publication Date
WO2001091375A2 true WO2001091375A2 (fr) 2001-11-29
WO2001091375A3 WO2001091375A3 (fr) 2002-07-25

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PCT/US2001/015741 WO2001091375A2 (fr) 2000-05-19 2001-05-15 Procede et systeme de mesure de variation de retard unidirectionnelle

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EP (1) EP1282956A2 (fr)
JP (1) JP2003534715A (fr)
AU (1) AU2001263161A1 (fr)
CA (1) CA2409001A1 (fr)
MX (1) MXPA02011438A (fr)
WO (1) WO2001091375A2 (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003053002A3 (fr) * 2001-12-19 2003-09-04 Tropic Networks Inc Procede et systeme pour mesurer le temps d'attente et la perte de paquets dans un reseau
EP1638275A2 (fr) * 2004-08-18 2006-03-22 Wecomm Limited Transmission des paquets
EP1696687A1 (fr) * 2005-02-25 2006-08-30 Nec Corporation Sélection d'un canal de communication en fonction du temps d'arrivée des paquets et des signaux d'accusé de réception de paquets
EP2086176A1 (fr) * 2008-01-29 2009-08-05 Tellabs Oy Procédé et agencement pour déterminer les différences de délai de transmission
US20140160945A1 (en) * 2012-12-06 2014-06-12 Accedian Networks Inc. Using bandwidth measurements to adjust cir and eir on a sub-rate link
US9225634B2 (en) 2012-09-25 2015-12-29 Accedian Networks Inc. Modified ethernet preamble for inter line card communications in a modular communication chassis
US9407515B2 (en) 2012-09-07 2016-08-02 Accedian Networks Inc. Automatic discovery and enforcement of service level agreement settings
US10129123B2 (en) 2013-09-26 2018-11-13 Fujitsu Limited Measurement apparatus, communications apparatus, and relay apparatus
CN112600734A (zh) * 2020-12-11 2021-04-02 深圳金信诺高新技术股份有限公司 一种高精度测量无线通信系统单向时延的方法
US11005777B2 (en) 2018-07-10 2021-05-11 At&T Intellectual Property I, L.P. Software defined prober
WO2022174770A1 (fr) * 2021-02-20 2022-08-25 中国移动通信有限公司研究院 Procédé et dispositif de mesure de temps de transmission

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5767174B2 (ja) * 2012-07-18 2015-08-19 日本電信電話株式会社 遅延変動測定装置、遅延変動測定方法及び遅延変動測定プログラム
JP2015186087A (ja) * 2014-03-25 2015-10-22 株式会社Ｊｖｃケンウッド 計測装置、制御装置、計測方法、制御方法

Family Cites Families (2)

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US5793976A (en) * 1996-04-01 1998-08-11 Gte Laboratories Incorporated Method and apparatus for performance monitoring in electronic communications networks
AU1520999A (en) * 1997-11-07 1999-05-31 Visual Networks, Inc. Method and apparatus for performing service level analysis of communications network performance metrics

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7127508B2 (en) 2001-12-19 2006-10-24 Tropic Networks Inc. Method and system of measuring latency and packet loss in a network by using probe packets
WO2003053002A3 (fr) * 2001-12-19 2003-09-04 Tropic Networks Inc Procede et systeme pour mesurer le temps d'attente et la perte de paquets dans un reseau
EP1638275A2 (fr) * 2004-08-18 2006-03-22 Wecomm Limited Transmission des paquets
EP1638275A3 (fr) * 2004-08-18 2006-04-19 Wecomm Limited Transmission des paquets
US7551649B2 (en) 2004-08-18 2009-06-23 Wecomm Limited Transmitting packets of data
US7764693B2 (en) 2005-02-25 2010-07-27 Nec Corporation Radio communication system, base station control equipment, radio terminal, and radio communication method
EP1696687A1 (fr) * 2005-02-25 2006-08-30 Nec Corporation Sélection d'un canal de communication en fonction du temps d'arrivée des paquets et des signaux d'accusé de réception de paquets
EP2086176A1 (fr) * 2008-01-29 2009-08-05 Tellabs Oy Procédé et agencement pour déterminer les différences de délai de transmission
EP2101445A3 (fr) * 2008-01-29 2009-11-25 Tellabs Oy Procédé et agencement pour déterminer les différences de délai de transmission
US8027269B2 (en) 2008-01-29 2011-09-27 Tellabs Oy Method and arrangement for determining transmission delay
US8139499B2 (en) 2008-01-29 2012-03-20 Tellabs Oy Method and arrangement for determining transmission delay differences
CN101499936B (zh) * 2008-01-29 2013-07-10 特拉博斯股份有限公司 用于确定传输延迟差的方法和设置
US9407515B2 (en) 2012-09-07 2016-08-02 Accedian Networks Inc. Automatic discovery and enforcement of service level agreement settings
US10003506B2 (en) 2012-09-07 2018-06-19 Accedian Networks Inc. Automatic discovery and enforcement of service level agreement settings
US10341470B2 (en) 2012-09-25 2019-07-02 Accedian Networks Inc. Modified ethernet preamble for inter line card communications in a modular communication chassis
US9509810B2 (en) 2012-09-25 2016-11-29 Accedian Networks Inc. Modified ethernet preamble for inter line card communications in a modular communication chassis
US9225634B2 (en) 2012-09-25 2015-12-29 Accedian Networks Inc. Modified ethernet preamble for inter line card communications in a modular communication chassis
US20140160945A1 (en) * 2012-12-06 2014-06-12 Accedian Networks Inc. Using bandwidth measurements to adjust cir and eir on a sub-rate link
US10129123B2 (en) 2013-09-26 2018-11-13 Fujitsu Limited Measurement apparatus, communications apparatus, and relay apparatus
US11005777B2 (en) 2018-07-10 2021-05-11 At&T Intellectual Property I, L.P. Software defined prober
CN112600734A (zh) * 2020-12-11 2021-04-02 深圳金信诺高新技术股份有限公司 一种高精度测量无线通信系统单向时延的方法
CN112600734B (zh) * 2020-12-11 2021-09-28 深圳金信诺高新技术股份有限公司 一种高精度测量无线通信系统单向时延的方法
WO2022174770A1 (fr) * 2021-02-20 2022-08-25 中国移动通信有限公司研究院 Procédé et dispositif de mesure de temps de transmission
CN115038109A (zh) * 2021-02-20 2022-09-09 中国移动通信有限公司研究院 时延测量方法及设备

Also Published As

Publication number Publication date
WO2001091375A3 (fr) 2002-07-25
EP1282956A2 (fr) 2003-02-12
CA2409001A1 (fr) 2001-11-29
MXPA02011438A (es) 2004-09-09
JP2003534715A (ja) 2003-11-18
AU2001263161A1 (en) 2001-12-03

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