JP2002077160A - Network quality evaluating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a network quality evaluating device for reducing the influence of time correction caused by the deviation of measured time in steps in each probe. SOLUTION: In the network quality evaluating device, test packet data are extracted from a plurality of locations of a communication network by each probe and are stored in a memory with a time stamp based on the time of a local timer in each probe, and the communication quality of the network is evaluated based on the time difference of the time stamp of the same test packet data. In the network quality evaluating device, time is corrected by an inclined straight line obtained by dividing each correction time by a correction time interval when evaluating the communication quality of the network based on the time difference of the time stamp of the same test packet data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network quality evaluation apparatus, and more particularly to an improvement in time correction of an apparatus for extracting and evaluating communication packets of a communication network at a plurality of locations.

[0002]

2. Description of the Related Art There is the Internet as a familiar communication network. On the Internet, not only textual information but also voice and image information can be exchanged as data.The services include data transmission services such as e-mail, net news, file transfer (ftp), remote login (telnet), Gopher, There are also information retrieval services such as WWW. According to the Internet, information can be exchanged instantaneously without being restricted by companies, countries, etc.,
It is widely used in various fields, such as individuals, companies, government agencies, educational institutions, and research institutions.

[0003] In the Internet, if the communication quality of the communication network does not sufficiently satisfy the quality required by the service to be used, packet data may be lost or delay time may fluctuate. In such a case, the received sound may be interrupted, or in the case of moving image information, the movement of the received moving image may be unnatural.

However, in the Internet, since a plurality of terminals and services share the route of the communication network, the communication quality is degraded when the number of users accessing simultaneously increases as compared with the case where the number of users is small. In addition, the bandwidth of a line constituting a communication network is generally designed so that a trunk portion is wide and a branch line portion is narrow. However, when actually operated, the branch line portion may be overloaded.

[0005] In any case, the provider must provide more stable services to the user from the standpoint of providing a part of the communication network for a fee. It is necessary to accurately analyze the cause. Further, it is desirable that the user can accurately grasp the quality of various services in real time in order to determine whether the quality of various services used on the Internet is commensurate with the usage fee of the communication network.

FIG. 3 is a block diagram showing an example of a conventional network quality evaluation device. In the figure, a communication network ISP1 is provided by a provider.
In the communication network ISP1, lines are connected to each other via a plurality of routers R. A company (head office) 2 and a company (branch) 3 as users are connected to the communication network ISP1 via a router R, and a probe manager 4 is also connected via the router R. In addition, other users and communication networks are also connected via a router, but they are not shown.

The probe P has a function of extracting packet data from the communication network, and is connected to a port of the router R from which the packet data is to be extracted, if necessary. The probe P apparently operates as a through circuit to extract packet data without disturbing communication, a physical layer circuit 6 for converting the extracted packet data into a logic signal, and a noticeable specified communication packet. A filter circuit 7 including a packet filter and a data filter for extracting only necessary information, a memory control circuit 9 for storing information extracted by the filter circuit 7 together with a time stamp in a memory 8, and an external communication circuit 10 for storing information stored in the memory 8 Probe Manager 4 via
And a local timer 12 for outputting time data serving as a time stamp.

In the configuration shown in FIG. 3, the probe manager 4 connects the packet information of interest extracted by the probe P connected to the port of the router R of the company (head office) 2 to the port of the router R of the company (branch office) 3. The same packet information of interest extracted by the extracted probe P is taken in, the packet information of both is collated, and packet loss / delay time / delay fluctuation between company (head office) 2 and company (branch office) 3 Measures communication quality items such as throughput.

However, the local timer 12, which outputs time data serving as a time stamp inside the probe P,
Since a time lag occurs in the long term, an NTP (not shown)
It is necessary to perform time correction periodically based on (Network Time Protocol) or external reference time.

[0010]

However, when the time of the local timer 12 is corrected, the time of the time stamp also changes stepwise in accordance therewith, so that a stepwise measurement time shift independent of the packet propagation time occurs. There is a problem that.

The present invention focuses on such a problem. An object of the present invention is to store a time correction time and a time in each probe and perform a correction operation based on these data, thereby providing a step-by-step method. It is an object of the present invention to realize a network quality evaluation device capable of reducing the influence of time correction caused by a large measurement time shift.

[0012]

According to the first aspect of the present invention, there is provided a method for extracting packet data from a plurality of locations on a communication network by using probes, based on the time of a local timer in each probe. In the network quality evaluation device that stores in the memory together with the stamp and evaluates the communication quality of the network based on the time difference between the time stamps of the same packet data, the time of the local timer in each probe is corrected based on the external time standard. A time correction event generation circuit that outputs a time and a correction time value as event data is provided. Event data output by the time correction event generation circuit is also stored in a memory, and network communication is performed based on a time difference between time stamps of the same packet data. In assessing quality, And correcting a slope straight line positive time divided by the correction time interval.

Thus, the propagation time of the test packet data can be accurately measured.

According to a second aspect of the present invention, in the network quality evaluation apparatus according to the first aspect, test packet data for measuring communication quality is transmitted to a communication network by triggering detection of deterioration of communication quality. .

Thus, when the deterioration of the communication quality is detected, the cause can be immediately investigated.

According to a third aspect of the present invention, in the network quality evaluation apparatus according to the second aspect, packet data equivalent to a case where deterioration of communication quality is detected is used as test packet data.

Thus, the cause of the deterioration of the communication quality can be determined in a state in which the conditions that caused the deterioration are reproduced.

A fourth aspect of the present invention is characterized in that, in the network quality evaluation device according to the second aspect, predetermined packet data suitable for specifying an estimated cause of deterioration is used as the test packet data.

Thus, when the cause of the deterioration of the communication quality can be empirically and statistically estimated, it can be quickly investigated.

[0020] Claim 5 of the present invention relates to claims 1 to 4.
The network quality evaluation device according to any one of the above, wherein the measurement port is of a through type.

Thus, measurement can be performed without disturbing the data transmission system.

Claim 6 of the present invention claims 1 to 4
In the network quality evaluation device according to any one of the above, the measurement port is a mirror type.

Thus, by connecting to a mirror port or a normal communication port of a router or a switch, it is possible to connect to a network without physically disconnecting a line.

[0024] Claim 7 of the present invention is claims 1 to 4.
Wherein the measurement port is switchable between a through port and a mirror port.

Thus, measurement can be performed at an appropriate port according to the network situation.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of an embodiment of the present invention, and portions common to FIG. 3 are denoted by the same reference numerals. 1 is different from FIG. 3 in that a time correction event generation circuit 13 is provided in FIG. When the local timer 12 is corrected based on the external reference time, the time correction event generation circuit 13 stores the time at which the correction was performed and the corrected time value in the memory 8 via the memory control circuit 9 in the event data. To be stored.

The operation of FIG. 1 will be described. As in the prior art, the probe manager 4 checks the packet information of interest extracted by the probe P connected to the router R port of the company (head office) 2 and the probe P connected to the router R port of the company (branch office) 3. The same packet information of interest and the time stamp extracted in step (1) are fetched, the packet information of the two is collated, the time difference between the time stamps is obtained, and the packet loss / delay between the company (head office) 2 and the company (branch office) 3 Measures communication quality items such as time, delay fluctuation, and throughput.

At this time, as shown in FIG. 2, the probe manager 4 performs the operation correction for the time difference using the event data when the time correction is performed in each probe, and performs the stepwise time correction. Reduce the impact.

FIG. 2A is a conceptual explanatory diagram of the time correction of the local timer 12 in each probe. The solid line shows the measured delay value, and the broken line shows the time correction value performed at an arbitrary correction time interval. This shows a stepwise change.

FIG. 2B is a diagram for explaining the calculation correction in the probe manager 4 using the time correction event data. The solid line shows the measured delay value after the calculation correction, and the broken line shows the delay value after the calculation correction. The change of the time correction value is shown. Here, the arithmetic correction is performed based on a slope straight line obtained by dividing the correction time by the correction time interval.

Further, the probe manager 4 detects the deterioration of the communication quality and fetches the information of the communication packet in which the deterioration has occurred from one of the probes P.
The information is transmitted to each probe P. Each probe P generates a test packet as described above based on this packet information and outputs it to the communication network ISP1.

That is, in each probe P, since the test packet passes through the tap circuit 5, each probe P
In the same manner as described above, it is taken into the memory 8 together with the time stamp. Data on these test packets taken into the memory 8 of each probe P is stored in the probe manager 4
Is transmitted to

The probe manager 4 selects and verifies the information of the two probes P by sequentially switching the combination of the routers R in the communication network ISP, and measures the communication quality in each combination of the routers R. For example, the delay time and the fluctuation of the delay time can be measured by comparing the reception time on the receiving side with the time stamp added to the packet data.

As described above, when the deterioration of the communication quality is detected, the packet communication using the same test packet as the communication packet having the deteriorated communication quality is performed between the probes P in the communication network ISP1. The communication quality between the routers R can be measured almost in real time, the combination of the routers R that deteriorates the communication quality can be accurately specified, and the cause analysis can be performed efficiently.

As a result, when the quality fluctuates for each service, the provider can appropriately analyze and grasp the cause of each fluctuation. In addition, the user can accurately grasp the quality of various services used on the Internet in real time, and obtain data for determining contract conditions with the provider.

It should be noted that the test packet is not necessarily limited to the packet based on the packet data when the quality is deteriorated. For example, the test packet may be arbitrarily created by the probe manager 4 for testing.

In addition, the measurement results of the communication quality for each combination of the routers R thus measured are displayed in a list. By making it different, the defective part can be clearly indicated.

The measurement port of the probe P may be of a through type for continuously passing packet data, a mirror port type using a mirror port for copying and transmitting packet data, Further, either one of them may be switched and set according to the situation.

The through type temporarily disconnects the line when connecting to the network, but after the connection, all packet data can be extracted while continuously passing the packet data without interruption, and the mirror port type However, when connecting to a network, there is a case where it is not necessary to physically disconnect the line, but all packet data flowing through the line may not completely flow through the mirror port. On the other hand, if the switching type is used, both advantages can be combined.

By the way, the communication route is changed according to the communication traffic situation in the communication network ISP1, but a large delay fluctuation occurs with the change of the route.
When detecting delay fluctuations in measuring communication quality,
The delay fluctuation is caused by communication network I such as router R
If it is possible to identify on the measurement result display screen whether it is caused by the inside of the apparatus constituting the SP1 or due to the above-mentioned route change, useless man-hours for finding the cause can be omitted.

FIG. 3 is a block diagram of a probe P to which such a path information analysis function is added, and portions common to FIG. 1 are denoted by the same reference numerals. In FIG. 3, a path information analysis circuit 14 is connected between the filter circuit 7 and the memory control circuit 9.

The operation of FIG. 3 will be described. For example, OSPF
In the case of using the (Open Short Path First) routing protocol, routing packets are exchanged between nodes of the network, and each node performs route calculation using topology information and link matrix information obtained from the information. Therefore, the probe P in FIG. 3 also captures packet data for delay measurement and also captures a routing packet, and detects that a route change has occurred.

Then, when the occurrence of the route change is detected, it is clearly indicated that the delay time has occurred due to the route change, such as "R1" or "R2" in FIG. As a result, it is possible to identify the delay time and the delay fluctuation in the normal operation state without the path change.

The probe for detecting a route change may be integrated with a probe for performing ordinary delay measurement, or may be individually and independently provided.

The connection position of the probe for detecting the route change is not limited to the user part, but may be any port in the communication network ISP1.

Although FIG. 3 shows an example in which a route change is detected by a routing packet, the present invention can be applied to detection of other events by using a packet relating to a special event arbitrarily designated by a user (operator). Packets related to special events, such as those sent when a router fails or those sent when traffic exceeds the maximum set value, are used.When these packets are detected, they are specific to each event indicating that fact. Is displayed as "R1" or "R2" in FIG.

As described above, by displaying the predetermined event mark on the quality time change display screen, it is possible to identify whether the measurement result of the delay time or the delay fluctuation is related to a special event or in the normal operation state.

[0048]

As described above, the network quality evaluation apparatus according to the present invention can reduce the influence of time correction caused by the stepwise measurement time shift, and can grasp and analyze the communication quality almost in real time. It is very beneficial for both the provider of the network and the users of the network.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is a block diagram showing another example of the embodiment of the present invention.

FIG. 4 is a display example diagram of a measurement result.

FIG. 5 is a block diagram illustrating an example of a conventional network quality evaluation device.

[Explanation of symbols]

 1 ISP 2 Company (Head Office) 3 Company (Branch) 4 Probe Manager P Probe

Claims (7)

[Claims] 1. A method for extracting packet data from a plurality of locations in a communication network using a probe, storing the extracted packet data in a memory together with a time stamp based on the time of a local timer in each probe, and based on a time difference between time stamps of the same packet data. In a network quality evaluation device for evaluating the communication quality of a probe, there is provided a time correction event generation circuit for outputting the time and the correction time value of the time correction of the local timer inside each probe based on an external time reference as event data. The event data output by the time correction event generation circuit is also stored in the memory, and when evaluating the communication quality of the network based on the time difference between the time stamps of the same packet data, a slope line obtained by dividing each correction time by the correction time interval. It is characterized by correcting with Network quality assessment device that. 2. The network quality evaluation device according to claim 1, wherein test packet data for communication quality measurement is transmitted to a communication network by detecting deterioration of communication quality as a trigger. 3. The network quality evaluation device according to claim 2, wherein packet data equivalent to a case where deterioration of communication quality is detected is used as the test packet data. 4. The network quality evaluation device according to claim 2, wherein predetermined packet data suitable for specifying an estimated cause of deterioration is used as the test packet data. 5. The network quality evaluation device according to claim 1, wherein the measurement port is of a through type. 6. The network quality evaluation device according to claim 1, wherein the measurement port is of a mirror type. 7. The measurement port according to claim 1, wherein said measurement port is switchable between a through type and a mirror type.
The network quality evaluation device according to any one of the above.