JP4204053B2 - Method and apparatus for isolating quality degradation point of packet switching network, and program and recording medium thereof - Google Patents

Description

  The present invention relates to network performance management in a packet switching network such as the Internet, and in particular, packet switching that provides a technique and a mechanism for identifying and quickly identifying a degradation location when quality degradation occurs in a communication service. The present invention relates to a method and apparatus for isolating a quality degradation point on a network, a program thereof, and a recording medium.

  A conventional method for identifying a quality deterioration point of a packet switched network service mainly has a communication confirmation by ping or the like from the network side. This is a program that sends a response request to the destination host using ICMP (Internet Control Message Protocol). Some implementations have a function to check the turnaround time until a response is returned depending on the implementation. Yes, it can be used as a measure of the congestion of the route to the destination.

  According to Non-Patent Document 1, in the confirmation method such as ping, a point that becomes a service interface between the network side and the user side, particularly the network and the user (responsible decomposition point on service), or a router or the like located in the vicinity thereof By transmitting a test packet (probe packet) such as ping to the apparatus and examining the status of the response packet, it is determined whether or not the packet has reached the user side. Specifically, check the ratio of the packets that have not been sent out of the sent packets, the time required for the response packet to return, and if these values are within the preset allowable range, Is considered to be due to the user environment.

Translated by Jun Murai, “Internet System Handbook”, published by Impress

However, such a conventional technique can check whether or not an IP packet has arrived, but has the following problems. That is,
1) The quality degradation cannot be detected if the test packet transmission characteristics (transmission interval, packet length, etc.) are different from the actual communication traffic characteristics.
2) If the communication protocol (for example, ICMPoverUDP in the case of ping) is different, the way of handling in the NW device (the router will give priority to transfer processing and the response to ping may be delayed) is the actual communication Unlike the test packet behavior alone, quality degradation cannot be detected accurately,
3) In quality measurement using test packets, a load is applied to the NW, so it is generally unsuitable for continuous measurement and will be confirmed afterwards.
There were problems such as.

(the purpose)
An object of the present invention is to solve such a conventional problem, and performs quality measurement (passive measurement) by capturing a circulating packet while receiving a communication service using an actual communication protocol. Thus, while avoiding these problems, quality degradation of the packet switching network that can identify quality degradation caused by the user environment, for example, packet loss in the user's LAN environment, PC performance problems, etc. at an early stage An object of the present invention is to provide a method and apparatus for dividing a portion, a program thereof, and a recording medium.

In the packet switching network according to the present invention, the quality degradation location isolation device arranges packet monitoring means at the isolation point on the transfer path through which the packet flow of the measurement target service passes,
Based on the captured packet information, a quality evaluation index (response time) indicating downstream performance is calculated in the packet monitoring unit based on the received packet being provided and the reception confirmation packet. And a means for identifying a deteriorated part based on the quality evaluation index value. Note that the transmission side (network side) is referred to as an upstream portion and the reception side (user terminal side) is referred to as a downstream portion from the separation point.

  Further, in the quality degradation location categorizing apparatus, the quality evaluation index indicating the performance of the downstream portion does not depend on the presence or absence of degradation due to packet loss in the middle of the upstream portion, and the degradation determination caused only by the downstream portion This is characterized in that the reception packet that can be received depends on the time (response time) from when the reception confirmation packet passes through the monitoring point until it passes through the monitoring point.

  In the packet switching network according to the present invention, the method of isolating the quality degradation portion captures the transmission packet of the communication flow and the reception confirmation packet at one point on the transfer path of the communication flow with respect to the packet communication flow using the reception confirmation signal. This is a method of calculating the response time downstream from the capture point by using the header information of the captured packet, and receiving multiple reception confirmation packets by identifying the sequence number included in the reception confirmation packet In this case, when there is a step of calculating the response time of each transmission packet based on the above determination and a retransmission packet for packet loss in the downstream part, the packet is retransmitted as the first transmission packet. The transmission packet is determined, and the confirmation packet is finally sent from the first transmission packet. It measures the time until the signal is characterized by having a step of calculating the response time.

  According to the present invention, when communication quality degradation occurs, for example, whether a user environment has a cause of degradation or a cause of degradation on the network side is received after the received packet passes the monitoring point. By using the time (response time) until the confirmation packet passes the monitoring point as an evaluation index, it is possible to determine whether or not the cause of the deterioration is in the user environment. Can be minimized. In addition, the user side can narrow down the deteriorated parts at an early stage, and there is a remarkable effect that appropriate measures can be taken.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a configuration diagram of a device for isolating a quality deterioration portion of a packet switching network according to an embodiment of the present invention.
As shown in FIG. 2, the quality degradation location isolating apparatus 20 according to the present embodiment captures a measurement / management target, that is, a transmission / reception packet 10 and captures data described in a header. The quality degradation point isolating device 20 receives the measurement time of the transmission packet as the target and the passive measurement means 21 that measures the passage time of the reception packet as the target, and the data measured by the passive measurement means 21 to receive the quality evaluation. A quality evaluation index calculation unit 22 that calculates an index and a quality deterioration point determination unit 23 that receives data calculated from the quality evaluation index calculation unit 22 and determines a quality deterioration point are provided. In addition, data is acquired from the transmission / reception packet 10 to be measured and managed, the passive measurement means 21 is controlled, data is received from the quality degradation point determination means 23, and data such as degradation factor information and evaluation index values is remotely controlled. Is provided to a designated location (such as a management device).
Each of these means 21 to 24 is configured by a computer, and holds dedicated data necessary for each function in a dedicated memory or a shared memory.

FIG. 1 is a process flowchart of a method for isolating a quality degradation point in a packet switching network according to an embodiment of the present invention.
First, a monitoring point is arranged at an intermediate point between the network and the user terminal, and if a transmission packet is transmitted from the network side to the user terminal, the target transmission packet is captured at the monitoring point and is directly Relay transmission to user terminal. If a reception packet responding to the transmission packet is sent from the user terminal to the network, the target reception packet is captured at the monitoring point and relayed to the network as it is (step 101). .

The passive measuring means 21 of the quality degradation point categorizing apparatus 20 measures the response time (referred to as an evaluation scale) from the passage of the target transmission packet to the passage of the same target reception packet. The quality evaluation index calculating means 22 calculates a quality evaluation index (evaluation scale) (step 102). Next, the quality degradation point determination unit 23 determines the quality degradation point based on the data received from the quality evaluation index calculation unit 22, and transfers the determination data to the remote operation unit 24 (step 103).
It should be noted that a method for capturing a target transmission / reception packet by the passive measurement unit 21, a method for calculating a quality evaluation index on the user side by the quality evaluation index calculation unit 22, and a deterioration on the user side by the quality degradation point determination unit 23. The method for determining the presence / absence will be sequentially described later.

FIG. 3 is a block diagram including a management device 40 that receives data such as deterioration factor information and evaluation index values from the remote control means 24 by remote control. FIG. 4 is a configuration diagram of a network system with a wider range.
The quality degradation point isolating device 20 arranged at the monitoring point is called the component 1, and the management device (operation IF etc.) 40 arranged at the remote place is called the component 2.
As shown in FIG. 3, a measurement target instruction or the like is transmitted in advance from the management device 40 to the remote operation means 24 of the quality degradation location isolating device 20. The measurement function unit 21 of the quality degradation location separating apparatus 20 takes in data necessary for passive measurement from the measurement target (transmission / reception packet) 10. An instruction from the management apparatus 40 and other instructions are input from the remote operation means 24 to the passive measurement means 21 so that measurements other than the instructions are not performed.

  The passive measuring means 21 measures the passing time of the target transmission packet and the passing time of the target received packet, and outputs the measurement data to the quality evaluation index calculating means 22. The quality evaluation index calculation unit 22 calculates a quality evaluation index based on the measurement data, and outputs the calculation result to the quality degradation point determination unit 23. The quality degradation location determination means 23 determines the quality degradation location in the route based on the received quality evaluation index. In addition, the coefficient α and the determination threshold value Z necessary for determination are input from the outside to the quality degradation point determination unit 23. The quality degradation location determination means 23 can determine degradation due to only the downstream portion without depending on the presence or absence of degradation due to packet loss in the middle of the upstream portion. That is, the presence / absence of deterioration depends on the value measured from the time (response time) until the reception confirmation packet passes through the quality degradation location isolating device 20 after the reception packet passes through the quality degradation location isolation device 20. Is determined.

  As shown in FIG. 4, a plurality of personal computers (PCs) 60 and routers 70 as user terminals are arranged in the downstream portion on the user terminal side from the quality degradation location separating apparatus 20. A router 80 in the network is arranged on the upstream side on the network side. As described above, the quality degradation location isolating device 20 that is the component 1 includes the passive measurement means 21, the quality evaluation index calculation means 22, the quality degradation location identification means 23, and the remote operation means (communication correspondence section) 24. The management device 40 of the component 2 that is provided and gives an instruction in advance to the quality degradation point isolating device 20 and is notified by the quality degradation location isolating device 20 is arranged outside or inside the network and includes an operation IF and the like. Has been.

(Capture of target send / receive packets)
FIG. 10 is a diagram illustrating an example of header information of a packet to be captured.
A transmission packet is transmitted from the service providing side, that is, the side receiving the service from the network side, that is, the user terminal side. On the other hand, a reception confirmation packet for the transmission packet is returned from the user side to the network side. Whether the packet is a reception confirmation packet for the corresponding transmission packet can be determined by identifying the sequence number described in the header of each packet.
A packet communication in which a reception confirmation packet corresponding to the transmission packet is returned to the transmission side and the identification data (sequence number or the like) of the corresponding transmission packet is included in the reception confirmation packet is targeted. Hereinafter, the implementation method will be described using TCP as an example.

The passive measuring means 21 of the quality degradation location isolating device 20 takes in the target packet and records the TCP packet header information and the monitoring point passage time.
FIG. 10 shows an example of information that can be acquired by TCP dump. The shaded portion is the information item corresponding to the above. That is, the information items are time, instruction source address, destination address, flag, sequence number, ACK bit, ACK number, and the like.
First, for a target communication (determined by a pair of IP address and port. You can specify communication between hosts with arbitrary or limited communication partners), a series of sent and received packets from session establishment to termination Each time (hereinafter referred to as “flow”), quality evaluation / degradation determination and the like are performed.

FIG. 5 is a format diagram of an ACK packet.
The following symbols are added to the capture information for each flow.
ti: transit time of the i-th received packet after communication is established Seq (i): sequence number Ack (i) in the TCP header of the i-th received packet: transmitted i-th after communication is established ACK
Ti: Time of passage of i-th transmitted ACK after communication is established Res (i): Space of sequence number confirmed to be received in Ack (i) For TCP with SACK option, received in Ack (i) As shown in FIG. 5, the space of the confirmed sequence number is included in the shaded portion between 1 to B1, B2 to B3, and B4 to B5. Therefore, the passive measurement means 21 identifies and discriminates the above-mentioned part of the captured ACK packet.

6, 7, and 8 are sequence charts when the packet is lost on the network side and when the packet is lost in the user environment in the normal state.
In the normal case of FIG. 6, the i-th packet is not lost and is transmitted from the network side to the user terminal side that has passed the monitoring point, and the ACK packet for the i-th packet from the user terminal passes the monitoring point. And sent back to the network side.
The passive measuring means 21 measures the time ti when the i-th packet has passed and the time Ti when the ACK packet for the i-th packet has passed in the reverse direction, and determines the times ti and Ti and the response time between them as quality. After passing to the evaluation index calculation means 22 and calculating the evaluation scale, the quality deterioration location determination means 23 identifies the downstream deterioration location.

  As shown in FIG. 7, when the packet (1) is lost on the network side, the time ti when the retransmission (IP) for the packet (1) passes through the monitoring point is measured, and the packet (1) for the packet (1) is received from the user terminal side. Time Ti at which the ACK packet passes through the monitoring point in the reverse direction is measured. After passing these times ti and Ti and the response time between them to the quality evaluation index calculation means 22 and calculating the evaluation scale, the quality deterioration point determination means 23 identifies the downstream deterioration point.

  As shown in FIG. 8, when the packet (1) is lost in the user environment, a retransmission (IP) for the packet (1) is transmitted. In the quality degradation location isolating apparatus 20, the first packet (1) is transmitted. The time ti that passes through the monitoring point is measured, and is not measured at the time that retransmission (IP) passes. From the user terminal side, a time Ti at which the ACK packet corresponding to the retransmission packet passes through the monitoring point in the reverse direction is measured. After passing these times ti and Ti and the response time between them to the quality evaluation index calculation means 22 and calculating the evaluation scale, the quality deterioration point determination means 23 indicates that the deterioration is not the downstream side but the upstream side deterioration. Discriminate and identify the deteriorated part. In this way, whether or not the deterioration is caused by the user environment can be determined by the response time.

(Calculation of quality evaluation index on the user side)
FIG. 9 is a flowchart of a quality evaluation index calculation process according to an embodiment of the present invention.
The time until the reception confirmation ACK for the packet that has passed through the monitoring point passes through the monitoring point is defined as a response time, and is used as an evaluation scale for determining deterioration due to user-side factors.
In preparation for calculating the response time, “Does {Seq (i) −1} belong to Res (j)? Is defined as a proposition (i, j). That is, it is a proposition to ask whether or not the receipt of the information of the i-th arrival packet is confirmed by the j-th ACK sent. Assuming that T is when the proposition (i, j) is true and F is false, the response time Ri for the packet that has passed the i-th monitoring point (toward the user) can be calculated by the following operation.

In FIG. 9, I is the total number of receptions, and J is the total number of receptions of ACK packets. Receiving total number 1 and every (step 201), it is greater than the passage time of the passage time is the i-th transmission packet in the ACK packet that has passed through the j-th, and determine the value of the smallest j (step 202), the value A proposition (i, j) is obtained based on j (step 203). If the proposition is false (F), the value of j is incremented by one (step 204), and the instruction (i, j) is obtained again. Note that TCP is a protocol that reliably transmits information by retransmission even when packet loss occurs in the middle, so the loops 203 and 204 are always terminated. When the proposition is true (T), the response time RI = Tj−tI is obtained (step 205). If I reaches the total number of receptions, the process is terminated. On the other hand, when I does not reach the total number of receptions, the value of I is incremented by 1 (step 206), and the process returns to step 202 again to obtain the value of J.
By following the above flow, the response time can be calculated.

The authenticity of the proposition can be confirmed as follows.
Since Res (j) is a set indicating the sequence of packets that have been confirmed to be received, its authenticity can be determined by whether or not Seq (i) -1 belongs to the area.
Note that when SACK is set to ON in the TCP option, the response time can be calculated by determining according to the above procedure even if the sequence number is lost due to packet loss.

(Determining whether the user has deteriorated)
A frequency distribution of {Ri} calculated in the description of FIG. 9 is created, and if the specified α% percentile value exceeds the specified determination threshold Z, it is determined that the quality is deteriorated due to the user side. However, there may be several types of determination threshold values Z depending on the user environment and the like.

(Other)
The function of the present invention is assumed to be incorporated as a monitoring function at a responsibility decomposition point on the transfer path through which the packet flow of the measurement target service passes.
It is assumed that a monitoring trigger, a determination result, and the like have a function corresponding to a remote inquiry from the downstream side (service user side) or the upstream side (network operator side).

(Program and recording medium)
If the flowchart of the quality evaluation index calculation process of FIG. 9 is programmed and the completed program is stored in a recording medium such as a CD-ROM, the recording medium is mounted on the computer of the quality evaluation index calculation means 22 and the quality is calculated. The present invention can be easily realized by installing the evaluation index calculation processing program in a computer and executing the program. Moreover, this program can be generalized by downloading this quality evaluation index calculation processing program from a computer with a recording medium attached thereto via a network to another computer.

It is a process flowchart which shows the principle of the isolation method of the quality degradation location of the packet switching network by this invention. It is a principle block diagram of the isolation device of the quality degradation location of the packet switching network by this invention. It is a block diagram which consists of the components 1 and 2 of this invention. It is a block diagram of the whole network which concerns on one Embodiment of this invention. It is a format figure of the ACK packet which this invention uses. It is a sequence chart for measuring the evaluation scale in the normal time which concerns on one Embodiment of this invention. It is a sequence chart when a packet is lost on the network side according to an embodiment of the present invention. It is a sequence chart when a packet is lost in a user environment according to an embodiment of the present invention. It is a flowchart of the calculation process of the quality evaluation index which concerns on one Embodiment of this invention. In this invention, it is a figure which shows the example of the packet header information etc. to capture.

Explanation of symbols

10 Targets of measurement and management (packets)
DESCRIPTION OF SYMBOLS 20 Quality degradation location isolation device 21 Passive measurement means 22 Quality evaluation index calculation means 23 Quality degradation location determination means 24 Remote operation means 40 Management apparatus 60 User terminal (PC)
70, 80 routers

Claims (5)

A first network and a second isolation device quality degradation point of the switching fabric that placed the cut point on transfer path packet flow passes between networks,
As a means of performing programmed computer processing,
In the first from the network side in providing service to be transmitted to the second network side packet, and a direction opposite to the packets in the service provided it is transmitted from the second network to the first network side a measuring means for storing in the memory to capture an acknowledgment packet for the packet in the service providing measures the passage time of the packet and the acknowledgment packet in the serving,
Calculating means for calculating, as a response time, a difference between the passing time of the packet providing the service measured by the measuring means and the passing time of the reception confirmation packet corresponding to the packet ;
The the calculation means based on the response time calculated is the second isolation device quality degradation point of the packet switching network, characterized in that it comprises a determination means for determining the presence or absence of deterioration of communication quality in the network side. A device for isolating a quality degradation point of a packet switched network according to claim 1,
The calculation means is
Determines whether the packet being provided by the measurement means is a retransmission packet or the first packet, and returns the difference between the passage time of the first packet and the passage time of the reception confirmation packet corresponding to the packet. An apparatus for classifying a quality deterioration point of a packet switching network, characterized in that it is calculated as time. A device for isolating a quality deterioration point of a packet switched network according to claim 1 or 2,
The calculation means is
The first to fourth procedures for each service providing packet and reception confirmation packet stored in the memory by the measurement means (from each reception confirmation packet stored in the memory, the transit time Tj (j = 1, 2,... Is a first procedure for obtaining the smallest reception confirmation packet j that is greater than the transit time tI of the I-th (I = 1, 2,...) Service providing packet,
A second procedure for determining whether or not (T) or (F) the received reception confirmation packet j is for reception confirmation of the I-th service providing packet;
If the determination result is NO (F), a third procedure for obtaining a reception confirmation packet with a determination result of (T) and a minimum passage time Tj;
Using the passage time Tj of the reception confirmation packet whose determination result is (T) and the passage time tI of the I-th service providing packet, the response time RI for the I-th service providing packet is set to RI = Tj− (Fourth procedure obtained by tI)
Are repeatedly performed in the order of the passage times, and the quality degradation section of the packet switching network is characterized in that The quality of communication quality on the second network side by programmed computer processing of the quality degradation location isolation device arranged at the isolation point on the transfer path through which the packet flow between the first network and the second network passes. A method for determining the presence or absence of deterioration,
As means for executing programmed computer processing, each means in the apparatus for isolating a quality degradation point of a packet switching network according to any one of claims 1 to 3,
The presence / absence of communication quality degradation on the second network side by executing each process in the device for identifying a quality degradation location of the packet switched network according to any one of claims 1 to 3 by each means provided A method for isolating a quality deterioration section of a packet switching network, characterized in that:   A program for causing a computer to function as each means in a device for isolating a quality deterioration point in a packet switching network according to any one of claims 1 to 3.

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