JP3824130B2 - Network quality evaluation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a network quality evaluation apparatus, and more particularly to improvement of time correction of an apparatus that extracts and evaluates communication packets of a communication network at a plurality of locations.
[0002]
[Prior art]
The Internet is a familiar communication network.
On the Internet, not only text information but also voice and image information can be exchanged as data, and its 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 instantly without being restricted by companies and countries, so it is widely used in various fields such as individuals, companies, government offices, educational institutions, and research institutions. Yes.
[0003]
By the way, in such an Internet, if the communication quality of the communication network does not sufficiently satisfy the quality required by the service to be used, packet data is lost or delay time fluctuates. If the received audio is interrupted, or if it is video information, the motion of the received video may become unnatural.
[0004]
However, in the Internet, a route along the communication network is shared by a plurality of terminals and services, so if the number of users accessing at the same time increases, the communication quality will be lower than when the number of users is small. In addition, the bandwidth of the lines constituting the communication network is generally designed such that the backbone portion is wide and the branch line portion is narrow, but the branch line portion may be overloaded when actually operated.
[0005]
In any case, the provider must provide a more stable service to users from the standpoint of providing a part of the communication network for a fee. It is necessary to analyze it.
It is also desirable for the user to be able to 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 communication network usage fee.
[0006]
FIG. 3 is a block diagram showing an example of a conventional network quality evaluation apparatus. In the figure, a communication network ISP1 is provided by a provider. In the communication network ISP1, the lines are connected via a plurality of routers R. A company (head office) 2 and a company (branch office) 3 as users are connected to the communication network ISP 1 via a router R, and a probe manager 4 is also connected to the communication network ISP 1 via the router R. In addition, other users and communication networks are also connected via a router, but not shown.
[0007]
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 packet data is to be extracted as necessary. The probe P apparently operates as a through circuit and extracts packet data without interfering with communication, a physical layer circuit 6 that converts the extracted packet data into a logic signal, and a specified communication packet to be noticed. 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 the memory 8, and information stored in the memory 8 for the external communication circuit 10 The control circuit 11 controls the transmission to the probe manager 4 via the local timer 12 and the local timer 12 outputs the time data to be a time stamp.
[0008]
In the configuration of FIG. 3, the probe manager 4 includes the packet information of interest extracted by the probe P connected to the port of the router R of the company (head office) 2 and the probe connected to the port of the router R of the company (branch office) 3. The packet information, the delay time, the delay fluctuation, the throughput, etc. between the company (head office) 2 and the company (branch office) 3 are collated by fetching the same packet information of interest extracted at P Measure communication quality items.
[0009]
However, the local timer 12 that outputs time data as a time stamp in the probe P causes a time lag in the long term, and therefore periodically based on an NTP (Network Time Protocol) or an external reference time (not shown). It is necessary to correct the time.
[0010]
[Problems to be solved by the invention]
However, when the time of the local timer 12 is corrected, the time of the time stamp also changes step by step accordingly, which causes a problem that a stepwise measurement time shift that does not depend on the packet propagation time occurs.
[0011]
The present invention pays attention to such problems, and its purpose is to store the time correction time and time in each probe, and perform a correction operation based on these data, thereby performing stepwise measurement time. An object of the present invention is to realize a network quality evaluation apparatus that can reduce the influence of time correction caused by a shift in time.
[0012]
[Means for Solving the Problems]
In order to achieve such an object, claim 1 of the present invention provides:
Packet data is extracted from multiple points in the communication network by probes and stored in memory together with time stamps based on the local timer time inside each probe, and network communication quality is evaluated based on the time difference between the time stamps of the same packet data. Network quality evaluation device
There is also provided a time correction event generation circuit that outputs the time of correction of the time of the local timer in each probe based on the external time standard and the correction time value as event data, and the event data output by the time correction event generation circuit is also provided. Store it in memory,
In evaluating the communication quality of the network based on the time difference between the time stamps of the same packet data, each correction time is corrected by an inclination straight line divided by the correction time interval.
[0013]
Thereby, the propagation time of the test packet data can be accurately measured.
[0014]
According to a second aspect of the present invention, in the network quality evaluation apparatus according to the first aspect, test packet data for communication quality measurement is transmitted to the communication network with detection of deterioration of communication quality as a trigger.
[0015]
Thereby, when the deterioration of the communication quality is detected, the cause can be immediately investigated.
[0016]
According to a third aspect of the present invention, in the network quality evaluation apparatus according to the second aspect, packet data equivalent to the case where deterioration of communication quality is detected is used as test packet data.
[0017]
As a result, the cause of the deterioration of the communication quality can be investigated in a state where the conditions causing the deterioration are reproduced.
[0018]
According to a fourth aspect of the present invention, in the network quality evaluation apparatus according to the second aspect, predetermined packet data suitable for specifying an estimated cause of deterioration is used as the test packet data.
[0019]
As a result, when the cause of the deterioration in communication quality can be estimated empirically and statistically, it can be quickly investigated.
[0020]
According to a fifth aspect of the present invention, in the network quality evaluation apparatus according to any one of the first to fourth aspects, the measurement port is a through type that allows packet data to pass continuously .
[0021]
Thereby, it can measure without disturbing a data transmission system.
[0022]
According to a sixth aspect of the present invention, in the network quality evaluation apparatus according to any one of the first to fourth aspects, the measurement port is a mirror type that copies and transmits packet data .
[0023]
Thus, by connecting to a mirror port of a router or switch or a normal communication port, it is possible to connect to the network without physically disconnecting the line.
[0024]
According to a seventh aspect of the present invention, in the network quality evaluation apparatus according to any one of the first to fourth aspects, the measurement port can be switched between a through type and a mirror type.
[0025]
As a result, measurement can be performed at an appropriate port according to the network status.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of an embodiment of the present invention, and the same reference numerals are given to the parts common to FIG. The difference between FIG. 1 and FIG. 3 is 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 sends the time when the correction is executed and the value of the corrected time to the memory 8 via the memory control circuit 9. Remember as.
[0027]
The operation of FIG. 1 will be described. The probe manager 4, as before, receives the packet information of interest extracted by the probe P connected to the port of the router R of the company (head office) 2 and the probe P connected to the port of the router R of the company (branch office) 3. The packet loss and delay between the company (headquarters) 2 and the company (branch office) 3 are obtained by comparing the packet information of the same packet information and time stamp extracted in step 2 Measure communication quality items such as time, delay fluctuation, and throughput.
[0028]
At this time, as shown in FIG. 2, the probe manager 4 performs calculation correction on the above time difference using event data when time correction is performed in each probe, and reduces the influence of stepwise time correction. To do.
[0029]
FIG. 2A is a conceptual explanatory diagram of the time correction of the local timer 12 in each probe, the solid line indicates the measured delay value, and the broken line indicates a stepwise correction of the time correction value performed at an arbitrary correction time interval. It shows a change.
[0030]
FIG. 2B is an explanatory diagram of calculation correction in the probe manager 4 using time correction event data. The solid line indicates the measured delay value after calculation correction, and the broken line indicates the time correction value after calculation correction. Shows changes. Here, the calculation correction is performed based on an inclination straight line obtained by dividing the correction time by the correction time interval.
[0031]
Further, the probe manager 4 detects the deterioration of the communication quality, fetches the information of the communication packet in which the deterioration has occurred from one of the probes P, and transmits the information 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.
[0032]
That is, since the test packet passes through the tap circuit 5 in each probe P, it is taken into the memory 8 together with the time stamp as in the case of each probe P. Data regarding these test packets taken into the memory 8 of each probe P is transmitted to the probe manager 4.
[0033]
The probe manager 4 selectively collates information of two probes P so as to sequentially switch the combination of routers R in the communication network ISP, and measures the communication quality in each combination of routers R.
For example, the delay time and the fluctuation of the delay time can be measured by collating the reception time on the receiving side with the time stamp added to the packet data.
[0034]
As described above, when the deterioration of the communication quality is detected, packet communication is performed between the probes P in the communication network ISP1 using the same test packet as the communication packet in which the deterioration of the communication quality occurs. Communication quality between routers R can be measured, the combination of routers R deteriorating communication quality can be accurately identified, and cause analysis can be performed efficiently.
[0035]
As a result, as a provider, when the quality fluctuates for each service, each cause can be accurately analyzed and grasped.
In addition, the user can accurately grasp the quality of various services used on the Internet in real time, and can obtain data for determining the contract conditions with the provider.
[0036]
Note that the test packet is not necessarily limited to that based on packet data at the time of quality deterioration, and may be arbitrarily created for testing by the probe manager 4, for example.
[0037]
Also, display the measurement results of communication quality for each combination of routers R measured in this way, and make the display color of the measurement results different from others, although the quality is worse than the quality limit setting value. You can clearly indicate the defect part.
[0038]
In addition, the measurement port of the probe P may be a through type that allows packet data to pass continuously, a mirror port type that uses a mirror port that copies and transmits packet data, or a situation. Depending on the situation, either of them may be set to be switched.
[0039]
The through type temporarily disconnects the line when connecting to the network, but after connection, all packet data can be extracted while continuously passing the packet data without interruption. The mirror port type is connected to the network. Although there is no need to physically disconnect the line when connecting, not all packet data flowing through the line may flow to the mirror port. On the other hand, if the switching type is used, both advantages can be combined.
[0040]
By the way, although the communication path is changed according to the communication traffic status in the communication network ISP1, a large delay fluctuation occurs with the path change. When delay fluctuation is detected in measuring the communication quality, whether the delay fluctuation is caused by the inside of the device constituting the communication network ISP1 such as the router R or the measurement result is displayed. If it can be identified on the screen, unnecessary cause investigation man-hours can be saved.
[0041]
FIG. 3 is a block diagram of the probe P to which such a path information analysis function is added, and the same reference numerals are given to portions common to FIG. In FIG. 3, a path information analysis circuit 14 is connected between the filter circuit 7 and the memory control circuit 9.
[0042]
The operation of FIG. 3 will be described. For example, when OSPF (Open Short Path First) routing protocol is used, 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. Yes. Accordingly, the probe P in FIG. 3 also captures the packet data for delay measurement and simultaneously captures the routing packet, and detects that a route change has occurred.
[0043]
When the occurrence of a route change is detected, for example, “R1” or “R2” in FIG. 4 clearly indicates that a delay time has occurred due to the route change. Thereby, it is possible to identify the delay time and the delay fluctuation in the normal operation state without the path change.
[0044]
The probe for detecting the path change may be integrated with a probe for performing a normal delay measurement, or may be individually independent.
[0045]
Further, the connection position of the probe for detecting the path change is not limited to the user part, and may be an arbitrary port in the communication network ISP1.
[0046]
Although an example in which a route change is detected by a routing packet has been described with reference to FIG. 3, it can also be applied to detection of other events by using a packet related to a special event arbitrarily designated by a user (operator). Packets related to special events, such as those sent when the router fails or those sent when the traffic exceeds the maximum set value, and when these packets are detected, are specific to each event indicating that Event symbols such as “R1” and “R2” in FIG.
[0047]
In this manner, by displaying a predetermined event mark on the quality time change display screen, it is possible to identify whether the measurement result of the delay time or delay fluctuation is related to a special event or in a normal operation state.
[0048]
【The invention's effect】
As described above, the network quality evaluation apparatus according to the present invention can reduce the influence of time correction caused by a stepwise measurement time shift and can grasp and analyze the communication quality almost in real time, thereby providing a network. It is extremely beneficial for both providers and users who use the network.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of an embodiment of the present invention.
FIG. 2 is an operation explanatory diagram 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 of measurement results.
FIG. 5 is a block diagram showing an example of a conventional network quality evaluation apparatus.
[Explanation of symbols]
1 ISP
2 companies (head office)
3 companies (branches)
4 Probe Manager P Probe

Claims (7)

Packet data is extracted from multiple points in the communication network by probes and stored in memory together with time stamps based on the local timer time inside each probe, and network communication quality is evaluated based on the time difference between the time stamps of the same packet data. Network quality evaluation device
There is also provided a time correction event generation circuit that outputs the time and correction time value of the local timer in each probe based on an external time reference as event data, and the event data output by the time correction event generation circuit is also provided. Store it in memory,
A network quality evaluation apparatus, characterized in that, when evaluating communication quality of a network based on a time difference between time stamps of the same packet data, each correction time is corrected by an inclination straight line divided by a correction time interval. 2. The network quality evaluation apparatus according to claim 1, wherein test packet data for measuring communication quality is transmitted to a communication network with detection of deterioration of communication quality as a trigger. 3. The network quality evaluation apparatus according to claim 2, wherein packet data equivalent to the case where deterioration of communication quality is detected is used as test packet data. 3. The network quality evaluation apparatus 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 apparatus according to claim 1, wherein the measurement port is a through type that allows packet data to pass continuously . 5. The network quality evaluation apparatus according to claim 1, wherein the measurement port is a mirror type that copies and transmits packet data . 5. The network quality evaluation apparatus according to claim 1, wherein the measurement port is switchable between a through type and a mirror type.

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