JP2002252649A - Method for determining link convergence, apparatus for implementing the same, program for processing the same and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which can accurately determine whether a link is converged and whether degradation of quality is caused by the link. SOLUTION: The method for determining a link convergence comprises: a step for calculating an average use rate of the link at predetermined intervals; a step for calculating the average number of simultaneous connecting flows passing through the link; a step for calculating the average number of the simultaneous connecting flows per the average use rate of the link when the calculated average use rate of the link is less than the first average use rate of the link; and a step for determining that the link is in a converged state when the calculated average use rate of the link is the second average use rate of the link or more and the calculated average number of the simultaneous connecting flows is greater than the product of the calculated average number of the simultaneous connecting flows per the average use rate of the link and the calculated average use rate of the link.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a link congestion judging device for judging whether or not congestion has occurred on a network, and is particularly effective when applied to a link congestion judging device for detecting a congestion state of a link of an IP network. It is about technology.

[0002]

2. Description of the Related Art Conventionally, various types of data processing have been used for IP (Intern
et Protocol) networks are being used, and the importance of IP networks is increasing. When such an IP network is used in many processes and the number of packets transmitted and received on the network increases, the amount of input packets may exceed the link bandwidth and cause congestion. Since this congestion has a great adverse effect on network functions, it is necessary to detect congestion on the network as soon as possible and eliminate it. In the current IP network management, whether or not a certain link is congested is determined mainly from the link usage rate. A method is also conceivable in which the throughput of a flow passing through a link is measured, and when a statistical value such as an average thereof falls below a certain threshold value, the state is determined to be congested.

[0003]

In the conventional IP network management, when it is determined from a link usage rate whether or not a certain link is congested, a relation between the link usage rate and a quality such as a throughput perceived by a user. Since it is unknown, it has been difficult to specifically specify the usage rate for determining the congestion state.

In a method of measuring the throughput of a flow passing through a link and determining a congestion state when a statistic such as an average falls below a certain threshold, 1) the throughput is measured by passing through the link. Capture all packets to be processed and assemble a flow to calculate throughput, or install a test packet transceiver at the front or rear stage or both of the link and actively measure throughput by transmitting test packets It is necessary and generally difficult. 2) Even if the link is not a bottleneck, the average throughput differs for each network depending on the state of the network before and after the flow passing through the link passes, There is a problem that it is difficult to specify a specific threshold value.

An object of the present invention is to solve the above-mentioned problems and to provide a technique capable of accurately determining whether a link is congested or whether the cause of quality deterioration is the link. is there.

[0006]

According to the present invention, there is provided a link congestion determining apparatus for determining whether or not congestion has occurred on a network, comprising: a link average usage rate at a predetermined time interval; The link congestion state is determined by observing the number of simultaneous connection flows.

In the present invention, in order to achieve the above object, the average of the throughput of a flow passing through a certain link is constant irrespective of the load when the link is not a bottleneck, and the number of simultaneously connected flows And the link average utilization rate is proportional, and when the link becomes a bottleneck, degradation of the average throughput is observed, and the number of simultaneous connection flows increases nonlinearly with the link average utilization rate. By observing the relationship between the number of concurrently connected flows and the average link utilization rate using the phenomenon, it is determined whether or not the link is a bottleneck.

That is, in the present invention, an average link utilization rate at a predetermined time interval is calculated, an average number of simultaneous connection flows passing through the link is calculated, and the calculated link average utilization rate is determined in advance. If the average link usage rate is less than the first link average usage rate that cannot be a bottleneck, the average number of simultaneous connection flows per link average usage rate is calculated.

Next, the calculated average link utilization rate is equal to or higher than a predetermined second average link utilization rate, and the calculated average number of simultaneous connection flows is equal to the calculated average simultaneous connection rate per link average utilization rate. When the number is larger than the product of the number of connection flows and the calculated link average usage rate, it is determined that the link is in a congested state.

[0010] Further, when the packet loss rate of the link is less than a predetermined first packet loss rate using the packet loss rate of the link, the average number of simultaneous connection flows per link average usage rate is calculated. The packet loss rate on the link is a predetermined second
When the packet loss rate is equal to or higher than the packet loss rate, the link congestion state may be determined.

A packet having the same transmission IP address, reception IP address, transmission port number, reception port number and transport protocol in the packet header is identified as the same flow, and packets belonging to the same flow are determined in advance. If the flow is not detected within the time, it is considered that the flow has been completed, and the average number of concurrently connected flows is calculated.
The average number of simultaneous connection flows may be calculated by detecting a SYN packet and a FIN packet in a (rotocol) packet.

As described above, according to the link congestion judging device of the present invention, the link congestion state is judged by observing the average link utilization rate in a predetermined time interval and the average number of simultaneous connection flows passing through the link. Therefore, it is possible to accurately determine whether the link is congested or whether the cause of the quality deterioration is the link.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a link congestion judging device for judging whether or not congestion has occurred on a network will be described below.

FIG. 1 is a diagram showing an example of a basic configuration of an IP network according to the present embodiment. As shown in FIG. 1, the link congestion determination device 100 is used in a form inserted into a link between nodes, and observes a link average usage rate in a predetermined time interval and an average number of simultaneous connection flows passing through the link. To determine the link congestion state.

FIG. 2 shows a link congestion determination device 1 according to the present embodiment.
It is a figure which shows the schematic structure of 00. As shown in FIG. 2, the link congestion determination device 100 of the present embodiment includes a packet header analysis unit 201, a link usage rate calculation unit 202, a simultaneous connection flow number calculation unit 203, and the number of simultaneous connection flows / usage ratio. It has a determination unit 204, a calculation unit 205 for the number of simultaneous connection flows per usage rate, and a link congestion determination unit 206.

The packet header analysis unit 201 is a processing unit that analyzes a header of a packet arriving from a preceding node, reads header information, and transmits the packet to a subsequent node. The link usage rate calculation unit 202 is a processing unit that calculates a link average usage rate in a predetermined time interval.

The simultaneous connection flow number calculation unit 203 is a processing unit that calculates an average number of simultaneous connection flows passing through the link. Number of simultaneous connection flows / usage rate adoption determination unit 20
A processing unit 4 checks whether or not the calculated link average usage rate is less than a predetermined first link average usage rate.

Number of simultaneous connection flows per utilization rate calculation unit 2
Reference numeral 05 denotes a processing unit that calculates an average number of simultaneous connection flows per link average usage rate when the calculated link average usage rate is less than a predetermined first link average usage rate.

The link congestion determining unit 206 determines that the calculated link average utilization rate is equal to or greater than a predetermined second link average utilization rate, and that the calculated average number of simultaneous connection flows is equal to the calculated link average utilization rate. A processing unit that determines that the link is in a congested state when the value is larger than the product of the average number of concurrently connected flows per link and the calculated average link utilization rate.

The link congestion determination device 100 includes a packet header analysis unit 201, a link usage rate calculation unit 202, a simultaneous connection flow number calculation unit 203, a simultaneous connection flow number / use rate adoption availability determination unit 204, a simultaneous connection flow per usage rate. A program for functioning as the number calculation unit 205 and the link congestion determination unit 206 is recorded on a recording medium such as a CD-ROM, stored on a magnetic disk or the like, and then loaded into a memory and executed. The recording medium for recording the program may be a recording medium other than the CD-ROM. In addition, the program may be installed in the information processing apparatus from the recording medium and used, or the recording medium may be accessed through a network to use the program.

FIG. 3 is a flowchart showing a processing procedure of the packet header analysis processing of the present embodiment. As shown in FIG. 3, the packet header analysis unit 201 of the link congestion determination device 100 performs a process of analyzing a header of a packet arriving from a preceding node, reading header information, and transmitting the packet to a subsequent node.

In step 301, the link congestion judging device 10
The packet header analysis unit 201 of 0 checks whether a packet has arrived from the preceding node, and proceeds to step 302 if the packet has arrived.

In step 302, the packet header of the arriving packet is analyzed, and the packet size, transmission IP address, reception IP address, transport protocol type, transmission port number, reception port number, TCP
Reads header information such as flags. In step 303, the packet from which the header information has been read is transmitted to the subsequent node.

In step 304, the read packet size is notified to the link utilization rate calculation unit 202. In step 305, the read header information such as the transmission IP address, the reception IP address, the transport protocol type, the transmission port number, the reception port number, and the TCP flag is notified to the simultaneous connection flow number calculation unit 203.

FIG. 4 is a flowchart showing the processing procedure of the link utilization rate calculation processing of this embodiment. As shown in FIG. 4, the link utilization rate calculation unit 20 of the link congestion determination device 100
2 performs a process of calculating an average link usage rate in a predetermined time interval.

In step 401, the link congestion judging device 10
The link utilization calculation unit 202 of 0 checks whether or not the packet size is notified from the packet header analysis unit 201, and proceeds to step 402 if the packet size is notified. In step 402, the sum of the notified packet size and the previously notified packet size is calculated.

In step 403, it is checked whether or not a predetermined time t0 has elapsed.
If has elapsed, the process proceeds to step 404. In step 404, the link average utilization ratio ρ for each t0 is calculated by dividing the sum of the packet sizes passed during the predetermined time t0 by t0 and the link bandwidth. In step 405, the calculated link average usage rate ρ is notified to the simultaneous connection flow number / usage rate adoption availability determination unit 204 and the link congestion determination unit 206. In step 406,
The variable storing the calculated sum of the packet sizes is initialized, and the process returns to step 401.

FIG. 5 is a flowchart showing a processing procedure of the simultaneous connection flow number calculation processing of the present embodiment. As shown in FIG. 5, the simultaneous connection flow number calculation unit 203 of the link congestion determination device 100 performs a process of calculating an average number of simultaneous connection flows passing through the link.

In step 501, the link congestion determination device 10
The number-of-simultaneous-connections flow calculation unit 203 receives a transmission IP address, a reception IP address, a transport protocol type, a transmission port number,
It is checked whether header information such as a reception port number and a TCP flag has been notified. If the header information has been notified, the process proceeds to step 502.

In step 502, the notified header information is compared with the previously notified header information, and the notified transmission IP address, reception IP address, transport protocol type, transmission port number, reception port It is checked whether the five values of the number are new. If the five values are new, it is determined that a new flow has occurred, and the process proceeds to step 503. In step 503, the simultaneous connection flow number counter is set to “1”. increase.

In step 504, it is checked whether a packet belonging to the existing flow has not arrived for a predetermined time t_fl. If the packet has not arrived for the time t_fl, it is determined that the flow has ended. Step 50
Proceed to 5 to decrease the simultaneous connection flow number counter by "1".

In step 506, it is determined whether or not a predetermined time t0 has elapsed.
If has elapsed, the process proceeds to step 507. In step 507, the average value of the above-mentioned simultaneous connection flow number counter is calculated to be the average number of simultaneous connection flows N, and
In step 08, the calculated average number of concurrently connected flows N is notified to the number of concurrently connected flows / usage rate adoption availability determination unit 204 and the link congestion determination unit 206.

FIG. 6 is a flowchart showing a processing procedure of a process of calculating the number of simultaneous connection flows per use rate according to the present embodiment. As shown in FIG. 6, the simultaneous connection flow number calculation unit 205 per usage rate of the link congestion determination device 100 calculates the link average usage rate when the calculated link average usage rate is less than a predetermined first link average usage rate. Processing for calculating the average number of simultaneous connection flows per link average usage rate is performed.

At step 601, the link congestion determination device 10
Number of simultaneous connection flows of 0 / use rate adoption availability determination unit 204
Checks whether the link average usage rate ρ and the average simultaneous connection flow number N are notified from the link usage rate calculation unit 202 and the simultaneous connection flow number calculation unit 203, and determines the link average usage rate ρ and the average simultaneous connection flow number N. Has been notified, the process proceeds to step 602.

In step 602, it is checked whether or not the notified link average usage rate ρ is less than a predetermined threshold ρ_0 which is the first link average usage rate, and the link average usage rate ρ is less than the threshold value ρ_0. Step 6 if
Go to 03. Here, it is assumed that the threshold value ρ_0 is a link average usage rate that cannot be a bottleneck. Step 6
In 03, the notified value (ρ, N) is notified to the number-of-simultaneously-connected-flows-per-use rate calculation unit 205.

In step 604, the concurrent connection flow number per utilization rate calculation unit 205 substitutes the notified link average utilization rate ρ and average concurrent connection flow number N into the following equation (1) to obtain Average number of simultaneous connection flows R
To update. Here, a in Equation 1 is a smoothing parameter.

[0037]

## EQU1 ## R ← (1-a) × R + N / ρ × a

FIG. 7 is a flowchart showing the processing procedure of the link congestion determination processing of this embodiment. As shown in FIG. 7, the link congestion determination unit 206 of the link congestion determination device 100
The calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and the calculated average simultaneous connection flow number is equal to the calculated average simultaneous connection flow number per link average usage rate. If it is larger than the product of the calculated link average usage rate, a process of determining that the link is congested is performed.

In step 701, the link congestion determination device 10
0 of the link congestion determination unit 206
It is checked whether or not the link average usage rate ρ and the average number of simultaneous connection flows N have been notified from the H.02 or the simultaneous connection flow number calculation unit 203. Goes to step 702.

In step 702, it is checked whether or not the notified link average usage rate ρ is equal to or greater than a predetermined second link average usage rate threshold ρ_1. Step 7 if
Go to 03. Here, the threshold ρ_1 is a value larger than the threshold ρ_0, but the same value as the threshold ρ_0 may be used.

In step 703, it is checked whether or not the notified average simultaneous connection flow number N satisfies the following expression 2. If the expression 2 is satisfied, the process proceeds to step 704. Here, R in Expression 2 is the average number of simultaneous connection flows per link average usage rate calculated by the number of simultaneous connection flows per usage rate calculation unit 205, and ε is a predetermined constant.

[0042]

## EQU2 ## N ≧ ρ × R × (1 + ε)

In step 704, it is determined that the link is in a congested state, and a result indicating that the link is in a congested state is output to the output device of the link congestion determining apparatus 100.

FIG. 8 is a flowchart showing a processing procedure of a process of calculating the number of simultaneous connection flows per usage rate in consideration of the packet loss rate according to the present embodiment. As shown in FIG. 8, the simultaneous connection flow number calculation unit 205 per usage rate of the link congestion determination device 100 considers whether the packet loss rate on the link is less than a predetermined first packet loss rate. Alternatively, a process of calculating the average number of simultaneous connection flows per link average usage rate may be performed.

That is, in step 801, the number of concurrently connected flows per usage rate calculation unit 205 determines that the packet loss rate L notified from the node connected to the link congestion determination apparatus 100 is the first packet loss rate L which is determined in advance. It is determined whether or not the packet loss rate L is less than the threshold value L0. If the packet loss rate L is less than the threshold value L0, the process proceeds to step 603. In other processing steps, the same processing as that described in FIG. 6 is performed.

FIG. 9 is a flowchart showing the processing procedure of the link congestion determination processing in consideration of the packet loss rate according to the present embodiment. As shown in FIG. 9, the link congestion determining unit 206 of the link congestion determining apparatus 100 determines whether the link is congested by considering whether the packet loss rate of the link is equal to or greater than a predetermined second packet loss rate. May be performed.

That is, in step 901, the link congestion determination unit 206 determines that the packet loss rate L notified from the node connected to the link congestion determination apparatus 100 is equal to or greater than the predetermined second packet loss rate threshold L 1. It is determined whether or not the packet loss rate L is equal to or larger than the threshold value L1. Here, the threshold value L1 is a value larger than the threshold value L0, but the threshold value L0
The same value as may be used. The other processing steps are shown in FIG.
It is assumed that the same processing as that described above is performed. Further, the process of calculating the number of simultaneous connection flows per usage rate in consideration of the packet loss rate in FIG. 8 and the link congestion determination process in consideration of the packet loss rate in FIG. 9 may be combined.

FIG. 10 is a flowchart showing the processing procedure of the simultaneous connection flow number calculation processing based on the detection of the SYN packet and the FIN packet according to the present embodiment. As shown in FIG. 10, when the transport protocol is TCP, the simultaneous connection flow number calculation unit 203 of the link congestion determination device 100 detects a SYN packet and a FIN packet and calculates the average number of simultaneous connection flows passing through the link. It may be calculated.

That is, in step 1001, the simultaneous connection flow number calculation unit 203 of the link congestion determination device 100 sends the transmission IP address and reception I
It is checked whether header information such as a P address, a transport protocol type, a transmission port number, a reception port number, and a TCP flag has been notified. If the header information has been notified, the process proceeds to step 1002.

In step 1002, it is checked whether or not the SYN bit in the TCP flag of the notified header information is set. If the SYN bit is set, it is determined that a new flow has occurred, and
Proceeding to 03, in step 1003, the simultaneous connection flow number counter is incremented by "1".

In step 1004, it is checked whether or not the FIN bit in the TCP flag of the notified header information is set. If the FIN bit is set, it is determined that the flow is terminated, and step 1 is executed.
Proceed to 005, and decrement the simultaneous connection flow number counter by “1”.

In step 1006, it is determined whether or not a predetermined time t0 has elapsed.
If t0 has elapsed, the process proceeds to step 1007. In step 1007, the average value of the simultaneous connection flow number counter is calculated to be the average simultaneous connection flow number N, and in step 1008, the calculated average simultaneous connection flow number N is determined as the number of simultaneous connection flows / usability of adoption. Notifying section 204 and link congestion determining section 206.

FIG. 11 is a diagram showing an example of increasing / decreasing the simultaneous connection flow number counter by detecting a SYN packet and a FIN packet according to the present embodiment. As shown in FIG. 11, in this method, the simultaneous connection flow number counter is increased by "1" when a SYN packet is detected, and the simultaneous connection flow number counter is decreased by "1" when a FIN packet is detected. .

FIG. 12 is a diagram showing the relationship between the number of simultaneous connections of flows passing through a certain link, the average throughput, and the usage rate in this embodiment. The relationship shown in FIG. 12 is generally obtained when the above three values are measured on a current link on the Internet.

In a region where a link does not become a bottleneck and the usage rate is below a certain value, the average of the throughput of the flow passing through the link is constant, and the number of concurrently connected flows and the usage rate are almost proportional to each other. The average throughput is degraded in a high utilization area where the link becomes a bottleneck, and the number of concurrently connected flows increases nonlinearly with respect to the utilization rate. Therefore, as described in the present embodiment, whether or not the link is congested can be determined by analyzing the relationship between the usage rate and the number of simultaneous connection flows.

As described above, in this embodiment, the link is congested by calculating the relationship between only the number of simultaneous connection flows and the average link utilization rate or the packet loss rate that are easily observed. It is possible to provide a link congestion determination device that determines whether or not the cause of the quality deterioration is the link.

As described above, according to the link congestion judging device of this embodiment, the link congestion state is observed by observing the average link usage rate and the average number of simultaneous connection flows passing through the link in a predetermined time interval. Since the determination is made, it is possible to accurately determine whether the link is congested or whether the cause of the quality deterioration is the link.

[0058]

According to the present invention, the link congestion state is determined by observing the average link utilization rate in a predetermined time interval and the average number of simultaneous connection flows passing through the link. It is possible to accurately determine whether or not the cause of the quality deterioration is the link.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a basic configuration of an IP network according to an embodiment.

FIG. 2 is a diagram illustrating a schematic configuration of a link congestion determination device 100 of the present embodiment.

FIG. 3 is a flowchart illustrating a procedure of a packet header analysis process according to the embodiment;

FIG. 4 is a flowchart illustrating a processing procedure of a link usage rate calculation process according to the embodiment;

FIG. 5 is a flowchart illustrating a procedure of a simultaneous connection flow number calculation process according to the embodiment;

FIG. 6 is a flowchart illustrating a procedure of a process of calculating the number of simultaneous connection flows per usage rate according to the embodiment;

FIG. 7 is a flowchart illustrating a procedure of a link congestion determination process according to the embodiment;

FIG. 8 is a flowchart illustrating a processing procedure of a process of calculating the number of simultaneous connection flows per usage rate in consideration of a packet loss rate according to the embodiment;

FIG. 9 is a flowchart illustrating a processing procedure of a link congestion determination process in consideration of a packet loss rate according to the present embodiment.

FIG. 10 is a flowchart illustrating a processing procedure of simultaneous connection flow number calculation processing by detecting a SYN packet and a FIN packet according to the embodiment;

FIG. 11 is a diagram illustrating an example of increasing / decreasing a simultaneous connection flow number counter by detecting a SYN packet and a FIN packet according to the embodiment;

FIG. 12 is a diagram illustrating a relationship between the number of simultaneous connections of a flow passing through a certain link, an average throughput, and a usage rate according to the embodiment;

[Explanation of symbols]

100: Link congestion determination device, 201: Packet header analysis unit, 202: Link usage rate calculation unit, 203: Simultaneous connection flow number calculation unit, 204: Simultaneous connection flow number / usage rate applicability judging unit, 205: Per usage rate , A link congestion determination unit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shin Koike 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 5K030 JA10 LC11 MB02 MB09 5K035 BB03 CC08 CC09 DD01 EE25

Claims (20)

[Claims] 1. A link congestion determination method for determining whether congestion has occurred on a network, comprising: calculating an average link utilization rate in a predetermined time interval; and an average simultaneous connection flow passing through the link. Calculating the number of links, and calculating the average number of simultaneous connection flows per link average usage rate when the calculated link average usage rate is less than a predetermined first link average usage rate; The calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and the calculated average number of simultaneous connection flows is calculated as the calculated average number of simultaneous connection flows per link average usage rate. Determining a link congestion state when the value is greater than a product of the link average utilization rate and the link congestion state. Constant method. 2. When the calculated link average usage rate is less than a predetermined first link average usage rate and the packet loss rate on the link is less than the predetermined first packet loss rate, The link congestion determination method according to claim 1, wherein the average number of simultaneous connection flows per link average usage rate is calculated. 3. The method according to claim 1, wherein the calculated link average utilization rate is equal to or greater than a predetermined second link average utilization rate, and the packet loss rate in the link is equal to or greater than the predetermined second packet loss rate. The link congestion state is determined when the calculated average number of simultaneous connection flows is larger than the product of the calculated average number of simultaneous connection flows per link average usage rate and the calculated link average usage rate. 3. The link congestion determination method according to claim 1 or 2. 4. A transmission IP address in a packet header,
A flow having the same reception IP address, transmission port number, reception port number, and transport protocol is identified as the same flow, and when a packet belonging to the same flow is not detected within a predetermined time, the flow is terminated. The link congestion determination method according to any one of claims 1 to 3, wherein the average simultaneous connection flow number is calculated by considering the number of simultaneous connection flows. 5. The link according to claim 1, wherein the average number of simultaneous connection flows is calculated by detecting a SYN packet and a FIN packet in a TCP packet. Congestion determination method. 6. A link congestion determining apparatus for determining whether congestion has occurred on a network, comprising: a link usage rate calculating unit for calculating a link average usage rate at a predetermined time interval; A simultaneous connection flow number calculation unit that calculates an average number of simultaneous connection flows; and an average simultaneous connection per link average usage rate when the calculated link average usage rate is less than a predetermined first link average usage rate. The number of simultaneous connection flows per usage rate for calculating the number of flows, and the calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and the calculated average simultaneous connection flow number is The link congestion state is larger than the product of the calculated average number of simultaneous connection flows per link average usage rate and the calculated link average usage rate. Link congestion judgment apparatus characterized by comprising a constant link congestion determination unit. 7. The simultaneous connection flow count per usage rate calculation unit, wherein the calculated link average usage rate is less than a predetermined first link average usage rate, and a packet loss rate on the link is determined in advance. 7. The link congestion determination device according to claim 6, wherein when the packet loss rate is less than the first packet loss rate, an average number of simultaneous connection flows per link average usage rate is calculated. 8. The link congestion determination unit according to claim 2, wherein the calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and a packet loss rate in the link is determined for the second packet. The link congestion state is determined when the calculated average number of simultaneous connection flows is equal to or larger than the loss rate and the calculated average number of simultaneous connection flows is larger than the product of the calculated average number of simultaneous connection flows per link average usage rate and the calculated link average usage rate. The link congestion determination device according to claim 6, wherein the link congestion is determined. 9. The simultaneous connection flow number calculation unit identifies a packet having the same transmission IP address, reception IP address, transmission port number, reception port number and transport protocol in a packet header as the same flow, 9. The method according to claim 6, wherein when the packets belonging to the same flow are not detected within a predetermined time, the flow is regarded as completed and the average number of simultaneous connection flows is calculated. Any one of
The link congestion determination device described in the paragraph. 10. The simultaneous connection flow number calculation unit,
The link congestion determination according to any one of claims 6 to 8, wherein the average number of simultaneous connection flows is calculated by detecting a SYN packet and a FIN packet in P packets. apparatus. 11. A program for causing a computer to function as a link congestion judging device for judging whether congestion has occurred on a network, comprising: calculating a link utilization ratio for calculating a link average utilization ratio in a predetermined time interval. Unit, a simultaneous connection flow number calculation unit for calculating an average simultaneous connection flow number passing through the link, and a link when the calculated link average usage rate is less than a predetermined first link average usage rate. A simultaneous connection flow count per usage rate calculation unit for calculating an average simultaneous connection flow count per average usage rate, wherein the calculated link average usage rate is equal to or greater than a predetermined second link average usage rate; The calculated average number of simultaneous connection flows is the calculated average number of simultaneous connection flows per link average utilization rate and the calculated link average. Program for causing a computer to function as determining link congestion judging unit and link congestion is greater than the product of the use rates. 12. The simultaneous connection flow count per usage rate calculation unit, wherein the calculated link average usage rate is less than a predetermined first link average usage rate, and a packet loss rate on the link is determined in advance. 12. The program according to claim 11, wherein when the packet loss rate is less than the first packet loss rate, the average number of simultaneous connection flows per link average usage rate is calculated. 13. The link congestion determining unit, wherein the calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and the packet loss rate in the link is determined by the second packet. The link congestion state is determined when the calculated average number of simultaneous connection flows is equal to or larger than the loss rate and the calculated average number of simultaneous connection flows is larger than the product of the calculated average number of simultaneous connection flows per link average usage rate and the calculated link average usage rate. 12. The method according to claim 11, wherein
Or the program according to claim 12. 14. The simultaneous connection flow number calculation unit, comprising: a transmission IP address, a reception IP address,
By discriminating a packet having the same transmission port number, reception port number and transport protocol as the same flow, and assuming that the flow has been completed if a packet belonging to the same flow is not detected within a predetermined time. 14. The program according to claim 11, wherein the program calculates the average number of simultaneous connection flows. 15. The simultaneous connection flow number calculation unit,
2. The average number of simultaneous connection flows is calculated by detecting a SYN packet and a FIN packet in P packets.
3. The program according to any one of 3. 16. A computer-readable recording medium storing a program for causing a computer to function as a link congestion determining device for determining whether congestion has occurred on a network, comprising: A link usage rate calculation unit for calculating a usage rate, a simultaneous connection flow number calculation unit for calculating an average simultaneous connection flow number passing through the link, and a first link average in which the calculated link average usage rate is predetermined When the usage rate is less than the usage rate, a simultaneous connection flow number per usage rate calculation unit that calculates an average number of simultaneous connection flows per link average usage rate; and a second link in which the calculated link average usage rate is predetermined. Is equal to or higher than the average usage rate, and the calculated average number of simultaneous connection flows is equal to the calculated link average usage rate. A computer-readable program for recording a program for causing a computer to function as a link congestion determining unit that determines a link congestion state when the number is equal to the product of the average number of simultaneous connection flows and the calculated link average usage rate Recording medium. 17. The simultaneous connection flow count per usage rate calculation unit, wherein the calculated link average usage rate is less than a predetermined first link average usage rate, and a packet loss rate on the link is determined in advance. 17. The computer-readable recording medium according to claim 16, wherein when the packet loss rate is less than the first packet loss rate, the average number of simultaneous connection flows per link average usage rate is calculated. 18. The link congestion determination unit, wherein the calculated link average usage rate is equal to or greater than a predetermined second link average usage rate, and the packet loss rate on the link is determined by a second packet. The link congestion state is determined when the calculated average number of simultaneous connection flows is equal to or greater than the loss rate and the calculated average number of simultaneous connection flows is larger than the product of the calculated average number of simultaneous connection flows per link average usage rate and the calculated link average usage rate. 17. The method according to claim 16, wherein
A computer-readable recording medium according to claim 17. 19. The simultaneous connection flow number calculation unit, comprising: a transmission IP address, a reception IP address,
By discriminating a packet having the same transmission port number, reception port number and transport protocol as the same flow, and assuming that the flow has been completed if a packet belonging to the same flow is not detected within a predetermined time. 19. The computer-readable storage medium according to claim 16, wherein the average number of simultaneous connection flows is calculated. 20. The simultaneous connection flow number calculation unit, comprising:
2. The average number of simultaneous connection flows is calculated by detecting a SYN packet and a FIN packet in P packets.
9. The computer-readable recording medium according to any one of 8 above.