Multiplex communications – Diagnostic testing – Determination of communication parameters
Reexamination Certificate
1999-10-19
2003-09-02
Chin, Wellington (Department: 2735)
Multiplex communications
Diagnostic testing
Determination of communication parameters
C370S248000, C370S241000, C370S232000, C370S233000, C370S234000, C370S253000, C709S224000, C709S225000, C709S226000, C709S227000, C709S228000
Reexamination Certificate
active
06614763
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a network communication performance measuring method and apparatus using a plurality of probing packets (as used herein, “probing” means issuing packets over networks for the purpose of measurement, and the packets used therefor are referred to as “probing packets”) to estimate available bandwidths of network paths, as well as to a computer readable record medium having a therein stored network communication performance measuring program, and more particularly to a network communication performance measuring method and apparatus ensuring an accurate estimation of path available bandwidths by use of a small number of probing packets, as well as to a computer readable record medium in which is stored the network communication performance measuring program.
2. Description of the Related Arts
In the event of providing high degree of services such as wide area load balancing or quality controls in internets or other communication networks, it is critical to measure available bandwidths of network paths to grasp what level of performances can be provided to users. These available bandwidths may differ to a large extent depending on the processing performances of the communication systems used, the processing abilities of routers lying on the communication paths, the line capacities, and the amount of traffics arising from other users. Conventional network performance measuring methods can include a technique in which the available bandwidths are actually measured through sending and reception of a multiplicity of, e.g., as much as 10,000 probing packets or a technique in which the path performances are estimated by a direct use of delay values of the probing packets.
However, in such a known available bandwidth actual measurement method using a multiplicity of probing packets, any excess load may inevitably act on the networks. The available band estimation method by direct use of delay measurement values of the probing packets may also suffer from a deficiency that the measurement errors are apt to become larger due to strongly affecting disturbances caused by other traffics.
SUMMARY OF THE INVENTION
According to the present invention there are provided a method of and an apparatus for measuring a network communication performance, ensuring an accurate estimation of available bandwidths, through sending and reception of a small number of probing packets via a network, without being influenced by any disturbances due to traffics, as well as a computer readable record medium in which is stored a network communication performance measuring program.
The network communication performance measuring method of the present invention comprises:
a sending step in which a sending unit sends a plurality of probing packets at equi-intervals into a network path;
a reception step in which a reception unit receives the plurality of probing packets;
a measurement step in which a measurement unit measures transmission time T(i) from the start of sending of each of the probing packets in the sending step up to the completion of reception of each of the probing packets in the reception step; and
an estimation step in which a performance estimation unit estimates an available bandwidth of the network path from correlations in difference between measurement packet transmission times T(i) measured in the measurement step.
It is to be appreciated that although the reception step and the measurement step follow the sending step, they may be processed at the same time during the sending of the plurality of probing packets in the sending step.
According to such a network communication performance measuring apparatus of the present invention, the network available bandwidth can be estimated by observing the correlations between the transmission times of the plurality of probing packets, whereby it is possible to estimate the available bandwidth, by use of a small number of, e.g., 100 to 200 probing packets, with a high accuracy due to lesser influence arising from other traffics.
The estimation step includes determining a ratio of the time during which the measurement packet transmission time exhibits a random behavior and judging, if the ratio is large and therefore the measurement packet is considered to be less influenced by queuing, that the sending speed of the measurement packet is smaller than the available bandwidth of the path, to thereby estimate the relation of magnitude in available bandwidth between the measurement packet and the path. For example, the estimation step includes finding a ratio giving
(
P
/&mgr;−&dgr;+&agr;)<&Dgr;
T
(
i
)<−(
P
/&mgr;−&dgr;)
where P (bit) is a size of the measurement packet, &dgr; (sec) is a measurement packet sending interval, &mgr; (bps) is a bottleneck link speed on a path to be measured, &agr; is a constant of the order of 0.001 to 0.0000001, and &Dgr;T(i) is a difference in transmission time between adjacent probing packets, which is defined as ((i+1)
th
measurement packet transmission time)−(i
th
measurement packet transmission time); the estimation step including judging, if the ratio is large with the consideration of the probing packets being less influenced by queuing, that the measurement packet sending speed is smaller than the path available bandwidth, to thereby estimate the relation of magnitude in available bandwidth between the measurement packet and the path.
A variant of the network communication performance measuring method of the present invention comprises:
a sending step for sending a plurality of probing packets at equi-intervals into a network path, the plurality of probing packets being designed to reach a predetermined reception site by way of a single or a plurality of predetermined node(s);
a reception step for receiving the plurality of probing packets at the predetermined reception site;
a measurement step for measuring transmission time from the start of sending of each of the probing packets in the sending step up to the completion of reception of each of the probing packets in the reception step; and
an estimation step for estimating a relation of magnitude between a measurement packet sending speed and a path available bandwidth, from correlations between the measurement packet transmission times measured in the measurement step.
In this case as well, the estimation step includes determining a ratio of the time during which the measurement packet transmission time exhibits a random behavior and judging, if the ratio is large and therefore the measurement packet is considered to be less influenced by queuing, that the sending speed of the measurement packet is smaller than the available bandwidth of the path, to thereby estimate the relation of magnitude in available bandwidth between the measurement packet and the path.
Also, the estimation step includes finding a ratio giving
(
P
/&mgr;−&dgr;+&agr;)<&Dgr;
T
(
i
)<−(
P
/&mgr;−&dgr;)
where P (bit) is a size of the measurement packet, &dgr; (sec) is a measurement packet sending interval, &mgr; (bps) is a bottleneck link speed on a path to be measured, &agr; is a constant of the order of 0.001 to 0.0000001, and &Dgr;T(i) is a difference in transmission time between adjacent probing packets, which is defined as ((i+1)
th
measurement packet transmission time)−(i
th
measurement packet transmission time); the estimation step including judging, if the ratio is large with the consideration of the probing packets being less influenced by queuing, that the measurement packet sending speed is smaller than the path available bandwidth, to thereby estimate the relation of magnitude in available bandwidth between the measurement packet and the path.
Another variant of the network communication performance measuring step of the present invention comprises:
a sending step for sending a plurality of probing packets at equi-intervals into a network path;
a reception step for receiving the plurality of probing packets at th
Aoki Takeshi
Kikuchi Shinji
Okano Tetsuya
Chin Wellington
Fujitsu Limited
Ho Chuong
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