JP3554214B2 - Apparatus and method for determining normality of traffic control function - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for determining the normality of a function for controlling traffic in a fixed-length packet network, and more particularly to an apparatus and a method for detecting a failure of a UPC apparatus provided in an ATM network.
[0002]
[Prior art]
ATMs have become widespread as one of the core technologies supporting communication services. In the ATM, various data such as voice data, image data, and text data are stored in fixed-length packets called cells and transmitted, so that various data can be handled in an integrated manner.
[0003]
FIG. 16 is a diagram showing a configuration of an ATM network. The ATM network 100 usually includes a plurality of ATM switches (ATM switches 110 to 130 in the figure) connected to each other. The terminal device is accommodated in an arbitrary ATM switch.
[0004]
When transmitting data from the transmitting terminal 140 to the receiving terminal 150, the ATM network 100 first establishes a virtual path and a virtual channel connecting the terminals. The transmitting terminal 140 stores data to be transmitted in one or more cells. Then, the transmitting terminal 140 sets VPI / VCI (virtual path identifier / virtual channel identifier) corresponding to the virtual path and the virtual channel in the header of each cell, and transmits the cells to the ATM network 100. The ATM network 100 transfers the cells to the receiving terminal 150 according to the VPI / VCI set in the header of each cell. Then, the receiving terminal 150 extracts the data stored in the cell received from the ATM network 100. As described above, in the ATM network, data is stored in cells and transmitted.
[0005]
In ATM, each user can usually select a communication service for transmitting data. The service provided to each user is set, for example, by a contract between the user and a communication carrier. The ATM Forum has service categories such as CBR (Constant Bit Rate), rt-VBR (Real Time Variable Bit Rate), nrt-VBR (Non Real Time Variable Bit Rate Rate), and UBR (Unavailable Rate). ) Is defined.
[0006]
The user declares communication parameters necessary for the selected service to the ATM network 100 in advance. As the communication parameters, for example, a peak cell rate PCR (Peak Cell Rate), an average cell rate SCR (Sustainable Cell Rate), a fluctuation absorption value, and the like are reported.
[0007]
ATM networks typically include UPC devices for monitoring and controlling traffic. As shown in FIG. 16, a UPC (Usage Parameter Control) device 111 is provided at the entrance of the ATM network 100, and monitors the amount of cells flowing into the ATM network 100 (that is, traffic) for each connection. I do. Specifically, the UPC device 111 monitors a cell rate for each connection, and monitors whether the cell rate does not exceed a value (for example, PCR) previously declared for the connection. When detecting a non-compliant cell (also referred to as a “violating cell”), the UPC device 111 discards the non-compliant cell or sets a low priority to the non-compliant cell. A cell to which a low priority is set can be discarded by an ATM switch earlier than a normal cell when the ATM network is congested. The “non-compliant cell” refers to a cell arriving at a cell rate higher than the declared value, or a cell having a shorter arrival time from the arrival time of the cell arriving earlier than the declared value.
[0008]
FIG. 17 is a block diagram of the UPC device. The UPC device includes an O / E unit 161 for converting an optical signal transmitted via a subscriber line into an electric signal, an assembly unit (SAT) 162 for assembling an ATM cell from a received signal, and an ATM from the subscriber line for each connection. UPC section 163 for monitoring and controlling the traffic of cells flowing into the network, OAM section 164 for providing an OAM (Operations And Maintenance) function, and E for converting an electric signal to be output to the subscriber line into an optical signal. / O element 165.
[0009]
The UPC section 163 determines whether the cell transmitted via the subscriber line is a compliant cell or a non-compliant cell. Compliant cells are input to the switch and non-compliant cells are discarded.
[0010]
FIG. 18 is a block diagram of an example of an existing UPC section. The delay unit 171 delays the received cell by a predetermined time in order to adjust the output timing of the cell. The timing generation unit 172 detects the head timing of the arrival cell, and instructs the calculation unit 176 on the timing at which the calculation should be performed. The cell identification unit 173 identifies a connection corresponding to a received cell based on the VPI / VCI of the cell. The parameter storage memory 174 stores various parameters declared for each connection, parameters used by the arithmetic unit 176, and the like. The CPU-IF 175 is an interface for writing parameters to the parameter storage memory 174. The arithmetic unit 176 extracts a parameter corresponding to the cell from the parameter storage memory 174 every time a cell is received, and performs a UPC operation using the parameter. By this UPC operation, it is determined whether the received cell is a compliant cell or a non-compliant cell. The discard control unit 177 outputs a compliant cell and discards a non-compliant cell according to the calculation result of the calculation unit 176.
[0011]
The operation algorithm of the UPC section is defined in ITU-T. At present, a leaky bucket algorithm and a virtual scheduling algorithm are employed. These two algorithms define substantially the same operation as each other. In these two algorithms, basically, the arrival interval of a cell is monitored for each connection, and it is determined whether or not the arrival interval violates a report value corresponding to the connection.
[0012]
[Problems to be solved by the invention]
As described above, the UPC device provides a function of monitoring and controlling traffic for each connection. For this reason, if the UPC device breaks down, for example, even if the actual traffic of a certain connection exceeds the declared value, the cells of the connection are not discarded and excess cells flow into the ATM network. Can occur. In this case, the cell of the connection according to the declared value may be erroneously discarded. Therefore, in order to avoid such a situation, the UPC device is provided with a function of monitoring the normality of its operation in real time.
[0013]
Conventionally, when detecting a failure of a UPC device, a periodically generated test cell has been used. In this test cell, a predetermined VPI / VCI is set, and is input to the UPC section 163 at a predetermined interval. In the UPC section 163, parameters corresponding to the interval are registered. When confirming that test cells are input at regular intervals using a counter, a timer, and the like, UPC section 163 determines whether the test cell is a compliant cell or a non-compliant cell. In this case, since the UPC device executes the calculation using the parameter corresponding to the predetermined interval, if the UPC unit is normal, the result should always be “compliant”. Therefore, when "non-compliance" is obtained as a result of the determination for the test cell, it is determined that the UPC device has failed.
[0014]
However, the above-described conventional method has a disadvantage that a failure of the UPC device cannot be detected unless a test cell is used. Use of a test cell causes a decrease in transmission efficiency. Moreover, the test cells must be generated at regular intervals, and if they are not generated at regular intervals, it cannot be correctly determined whether or not a failure has occurred.
[0015]
Further, in a configuration using test cells generated at regular intervals, parameters used for detecting a failure are limited to fixed values corresponding to the regular intervals. For this reason, it is difficult to test various parameters. Further, the determination as to whether or not the UPC device has failed can be made only at regular intervals.
[0016]
An object of the present invention is to provide a device capable of detecting a failure of a traffic control function using a desired parameter in a fixed-length packet network. Another object of the present invention is to provide a device capable of detecting a failure of a traffic control function without using a test packet in a fixed-length packet network.
[0017]
[Means for Solving the Problems]
The device of the present invention is a device for judging the normality of the function of controlling the traffic of fixed-length packets in a network transmitting fixed-length packets, and checks the normality of the function of controlling the traffic of fixed-length packets. Means for storing parameters for a fixed-length packet, and each time a fixed-length packet arrives, a connection is made to a connection corresponding to the fixed-length packet in a first period within a unit time allocated to the fixed-length packet. Calculating means for executing the UPC operation using the set parameters and performing the UPC operation using the parameters stored in the storage means during the second period within the unit time; and The normality of the function of controlling the traffic of the fixed-length packet is determined based on the result of the UPC operation by the arithmetic unit during the period. And a judgment means.
[0018]
In the above configuration, the calculation means executes the UPC calculation twice for each fixed-length packet. Based on the first UPC operation, it is determined whether the fixed-length packet is a compliant cell or a non-compliant cell in the connection corresponding to the fixed-length packet. Further, based on the second UPC operation, the normality of the function of controlling the traffic of the fixed-length packet is determined. Therefore, there is no need to use a test cell to determine the normality of the function of controlling the traffic of fixed-length packets. Further, by rewriting the parameters to be stored in the storage means, a test using various parameters can be easily performed.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. The present invention is widely applied to an apparatus for controlling traffic in a network transmitting fixed-length packets. In the following, an ATM network will be described as an embodiment. The configuration of the ATM network is, for example, as described with reference to FIG.
[0020]
FIG. 1 is a block diagram of a UPC unit which is a main part of the UPC device according to the present embodiment. The UPC unit is provided, for example, in the UPC device shown in FIG. 17, and the UPC device is provided, for example, at the entrance of the ATM network shown in FIG.
[0021]
1 used in FIG. 18 represent the same reference numerals. That is, the delay unit 171, the timing generation unit 172, the cell identification unit 173, the CPU-IF 175, and the discard control unit 177 are basically the same as existing ones.
[0022]
The parameter storage memory 1 stores test parameters (failure determination parameters) in addition to various parameters declared for each connection. Various parameters stored in the parameter storage memory 1 are written via the CPU-IF 175 according to an instruction from a CPU (not shown).
[0023]
FIG. 2 is a diagram schematically illustrating an example of the parameter storage memory 1. In the parameter storage memory 1, a “minimum cell interval value T” and a “fluctuation absorption value τ” are registered as parameters declared for each connection. The “minimum cell interval value T” is, for example, the reciprocal of the maximum cell rate (PCR). The “fluctuation absorption value τ” is, for example, CDV (Cell Delay Variation: cell delay variation), and is a parameter for absorbing the fluctuation of the cell interval on the transmission path.
[0024]
These parameters are given in units of time allocated to transmit one cell. For example, if "minimum cell interval value T = 10" has been declared and registered for a connection (#a), when the interval between cells flowing through the connection becomes shorter than "10", the declaration is made. A violation of the value will be detected. In the example shown in FIG. 3A, the interval between cells flowing via the connection #a is longer than the minimum cell interval value T, and no violation of the declared value has occurred. On the other hand, in the example shown in FIG. 3B, the interval between cells flowing through the connection #a is shorter than the minimum cell interval value T, and a violation of the declared value has occurred. In this case, the calculation unit 2 described later determines that the cell arrived at the time 9 is a “non-compliant cell”. Further, if a value other than 0 is declared and registered as the “fluctuation absorption value τ”, as shown in FIG. 3B, the interval between cells flowing through the connection #a becomes the minimum cell interval value T Even if the difference is shorter than the above, if the difference is within the “fluctuation absorption value τ”, it may be considered that no violation of the declared value has occurred.
[0025]
As the test parameters, in addition to “minimum cell interval value T” and “fluctuation absorption value τ”, “expected value of the number of passing cells” and “expected value of the number of discarded cells” are registered. The “expected value of the number of passing cells” is obtained when a UPC operation is performed on a predetermined number of cells using the “minimum cell interval value T” and the “fluctuation absorption value τ” registered as test parameters. Is the expected value of the number of compliant cells that would be obtained at On the other hand, the “expected value of the number of passing cells” is obtained by executing a UPC operation on a predetermined number of cells using the “minimum cell interval value T” and the “fluctuation absorption value τ” registered as test parameters. Is the expected number of non-compliant cells that would be obtained when
[0026]
Returning to the description of FIG. The operation unit 2 determines whether the input cell is a compliant cell or a non-compliant cell. That is, the arithmetic unit 2 detects a connection corresponding to the input cell, and extracts a parameter corresponding to the connection from the parameter storage memory 1. Then, the operation unit 2 executes the UPC operation using the parameters, and determines whether the input cell is a compliant cell or a non-compliant cell. The operation algorithm of the UPC operation employs a leaky bucket algorithm and a virtual scheduling algorithm in ITU-T.
[0027]
FIG. 3 is a flowchart of the basic processing of the virtual scheduling algorithm. This process is executed for each connection. This process is executed for each cell that arrives each time the cell arrives. In the following, a process after a cell arrives at time ta will be described.
[0028]
In step S1, it is checked whether the actual arrival time ta of the arrival cell is before or after the logical arrival time TAT of the arrival cell. At this time, the fluctuation absorption value τ is considered. Here, the logical arrival time TAT of the arrival cell has been previously calculated. The value read from the parameter storage memory 1 is used as the fluctuation absorption value τ.
[0029]
If the cell arrives after the logical arrival time TAT in consideration of the fluctuation absorption value τ, that is, if “ta ≧ TAT−τ”, the time between the arrival time of the previous cell and the arrival time of the current cell is Since the interval is longer than the declared value, information indicating that the arrival cell is a “conforming cell” is output in step 2. In step S3, a logical arrival time TAT for the next cell is calculated. Specifically, the time obtained by adding the increment value I to the later of the actual arrival time ta of the arrival cell and the logical arrival time TAT of the arrival cell is defined as the logical arrival time TAT of the next cell. The increment value I is, for example, a reciprocal of a transfer rate (for example, a maximum cell rate PCR) declared by a user for each connection. In the embodiment, the minimum cell interval value T read from the parameter storage memory 1 is used.
[0030]
On the other hand, if the cell arrives before the logical arrival time TAT in consideration of the fluctuation absorption value τ, that is, if “ta <TAT−τ”, the arrival of the current cell from the arrival time of the previous cell Since the interval until the time is shorter than the declared value, information indicating that the arrival cell is a “non-compliant cell” is output in step 4. If the cell arrives before the logical arrival time TAT in consideration of the fluctuation absorption value τ, the logical arrival time TAT is not updated. Through the above processing, it is determined whether the arrival cell is a compliant cell or a non-compliant cell.
[0031]
Although the virtual scheduling algorithm is shown in FIG. 4, the calculation unit 2 may determine whether the arrival cell is a compliant cell or a non-compliant cell by a leaky bucket algorithm. Further, the arithmetic unit 2 may be configured by hardware or software. However, it is necessary to quickly determine whether the arriving cell is a compliant cell or a non-compliant cell.
[0032]
FIG. 5 is a diagram illustrating the operation timing of the operation unit 2. The arithmetic unit 2 performs a UPC operation on a connection corresponding to a cell every time a cell arrives. However, the time required for the UPC operation is sufficiently shorter than the time allocated for transmitting one cell. Therefore, the operation unit 2 is in an unused state during a period from when the UPC operation is performed on a certain input cell to when the UPC operation is performed on the next input cell. That is, during this time, the arithmetic unit 2 can execute other processing.
[0033]
In the present invention, using this unused period, the arithmetic unit 2 is caused to execute the UPC operation using the test parameters. That is, the arithmetic unit 2 executes the following two UPC operations each time a cell arrives.
(1) UPC operation for connection corresponding to input cell
(2) UPC operation for detecting failure of UPC function (using test parameters)
When the UPC operation of the above (1) is completed, the operation unit 2 notifies the address selection unit 3 of the completion and outputs the judgment result. Subsequently, the operation section 2 executes the UPC operation of the above (2) and outputs the judgment result.
[0034]
When a cell arrives, the address selection unit 3 indicates a memory address corresponding to the connection that transmitted the cell. Each connection and each memory address are uniquely associated in advance. The connection corresponding to the arrival cell is identified by the cell identification unit 173 by the VPI / VCI of the arrival cell. Further, upon receiving from the arithmetic unit 2 a notification indicating that the UPC operation for the connection corresponding to the arrival cell has been completed, the address selecting unit 3 indicates a test memory address.
[0035]
The parameter storage memory 1 gives various parameters stored at the address specified by the address selection unit 3 to the calculation unit 2. Therefore, when a cell arrives, the operation unit 2 first receives parameters related to a connection corresponding to the cell, and subsequently receives test parameters. Note that the test parameters are given not only to the calculation unit 2 but also to the window generation unit 5, the passage measurement unit 6, and the discard measurement unit 7.
[0036]
The rewrite detection unit 4 detects that the test parameters in the parameter storage memory 1 have been updated according to an instruction from a CPU (not shown), and notifies the window generation unit 5 and the discard measurement unit 7 of the update.
[0037]
The window generation unit 5 generates a window representing a period determined based on the “minimum cell interval value T” registered as a test parameter. Here, the “minimum cell interval value T” is given in units of time allocated to transmit one cell, as described above. Therefore, the window generated by the window generating unit 5 substantially represents the number of cells to be monitored by representing a predetermined period.
[0038]
The passage measurement unit 6 calculates the number of cells actually determined to be “compliant” by the arithmetic unit 2 and the number of cells that will be determined to be “compliant” in the window generated by the window generation unit 5. Compare with expected value and output the comparison result. This expected value is an “expected value of the number of passing cells” registered in the parameter storage memory 1 as one of the test parameters. If the two values match each other, information indicating "normal" is output, and if they do not match, information indicating "abnormal" is output.
[0039]
In the window generated by the window generating unit 5, the discard measuring unit 7 determines the number of cells actually determined to be “non-compliant” by the arithmetic unit 2 and the number of cells that will be determined to be “non-compliant”. Compare the expected value of the number and output the comparison result. This expected value is the “expected value of the number of discarded cells” registered in the parameter storage memory 1 as one of the test parameters. If the two values match each other, information indicating "normal" is output, and if they do not match, information indicating "abnormal" is output. The detailed configurations and operations of the window generation unit 5, the passage measurement unit 6, and the discard measurement unit 7 will be described later.
[0040]
Next, the basic operation of the UPC section having the above configuration will be described. Here, as shown in FIG. 6, the cell 1, cell 2, cell 3,. . . . Arrive in order. It is also assumed that cells 1 to 3 have been transmitted via connections # 1 to # 3, respectively.
[0041]
When the cell 1 arrives, the cell identification unit 173 recognizes that the cell has been transmitted via the connection # 1 by analyzing the VPI / VCI of the header of the cell. Then, the arithmetic unit 2 extracts parameters (“minimum cell interval value T” and “fluctuation absorption value τ”) related to the connection # 1 from the parameter storage memory 1, and uses the parameters in the cell T1 during the period T1. Is a compliant cell or a non-compliant cell. This determination result is given to the discard control unit 177. Then, the discard control unit 177 passes the cell 1 or discards the cell 1 according to the determination result.
[0042]
When the UPC operation for the connection # 1 ends, the operation unit 2 starts the UPC operation for checking the UPC function. That is, the arithmetic unit 2 extracts the test parameters (“minimum cell interval value T” and “fluctuation absorption value τ”) from the parameter storage memory 1 and, during the period Tch, uses the parameters to make the cell 1 a compliant cell. It is determined whether the cell is a non-compliant cell. This determination result is provided to the passage control unit 6 and the discard control unit 7. When the result of the determination by the operation unit 2 is “compliant (ie, passing)”, the counter provided in the passage control unit 6 is incremented, while the determination result is “non-compliant (ie, discarded)”. If there is, the counter provided in the discard control unit 7 is incremented.
[0043]
Subsequently, when the cell 2 arrives, the arithmetic unit 2 extracts parameters related to the connection # 2 from the parameter storage memory 1, and uses the parameters in the period T2 to determine whether the cell 2 is a compliant cell or a non-compliant cell. Is determined. Then, the discard control unit 177 passes or discards the cell 2 according to the determination result.
[0044]
When the UPC calculation for the connection # 2 ends, the calculation unit 2 starts the UPC calculation for checking the UPC function again. That is, the operation unit 2 extracts the test parameters from the parameter storage memory 1 and determines whether the cell 2 is a compliant cell or a non-compliant cell in the period Tch for the cell 2 by using those parameters. . Then, a counter provided in the passage control unit 6 or the discard control unit 7 is incremented according to the determination result.
[0045]
Thereafter, similarly, every time a cell arrives, the operation unit 2 executes the UPC operation for the connection transmitting the cell and the UPC operation for checking the UPC function. As a result, the passage control unit 6 counts the “number of passing cells” that would be obtained if the UPC operation was performed using the test parameters. Then, the passage control unit 6 compares the “number of passing cells” counted in the window generated by the window generation unit 5 with the “expected value of the number of passing cells” registered in the parameter storage memory 1. Then, the normality of the UPC function is determined based on the comparison result. On the other hand, the discard control unit 7 counts the “number of discarded cells” that would be obtained if the UPC operation was performed using the test parameters. Then, the discard controller 7 compares the “number of discarded cells” counted in the window generated by the window generator 5 with the “expected value of the number of discarded cells” registered in the parameter storage memory 1. Then, the normality of the UPC function is determined based on the comparison result.
[0046]
The “expected value of the number of passing cells” and the “expected value of the number of discarded cells” are calculated in advance for the test parameters and stored in the parameter storage memory 1. Hereinafter, a method of calculating these expected values will be described.
[0047]
In the normal UPC operation, as described with reference to FIG. 6, each cell is identified by a connection, and a determination of compliance / non-compliance is made for each connection. That is, in the UPC operation for a certain connection, only the cells transmitted via the connection are targeted. For example, in the example shown in FIG. 6, only the cell 1 is targeted in the UPC calculation for the connection # 1.
[0048]
On the other hand, in the UPC operation for checking the UPC function, as described with reference to FIG. 6, all input cells are targeted. For example, in the example shown in FIG. 6, cell 1, cell 2, cell 3,. . . Are all subjected to the UPC operation for checking the UPC function. Here, “all input cells” basically do not matter whether they are user cells or control cells, and they do not matter whether they are valid cells or invalid cells. That is, in the UPC operation for checking the UPC function, it is assumed that the target cells have arrived continuously, and a determination of compliance / non-compliance is made for each of those cells.
[0049]
FIG. 7 is a diagram illustrating an example of an output that would be obtained as a result of the UPC operation for checking the UPC function if the operation unit 2 was normal. Here, a period that is five times the “minimum cell interval value T” given as a test parameter is defined as a monitoring period. For example, if “T = 3”, the monitoring period corresponds to the time allocated for transmitting 15 cells. In addition, the UPC operation follows the virtual scheduling algorithm (hereinafter, simply referred to as “VS algorithm”) shown in FIG.
[0050]
FIG. 7A shows a case where “minimum cell interval value T = 1” and “fluctuation absorption value τ = 0” are given as test parameters. In this case, the VS algorithm determines that the arriving cell is a compliant cell if the interval between the arrival time of a certain cell and the arrival time of a cell before that cell is “1” or more, and the interval is “ If it is smaller than "1", it is determined that the cell is a non-compliant cell. Note that the “minimum cell interval value T” corresponds to the increment value I in the VS algorithm.
[0051]
For example, if the cell arrives at time ta = 1 when the logical arrival time TAT is “1”, TAT = 1 and τ = 0 in step S1 of FIG. 4, and “ta = TAT-τ ”, the arrival cell is determined to be a compliant cell. Then, in step S3, "2" is generated as the logical arrival time TAT of the next arrival cell. Here, in the UPC operation for checking the UPC function, the target cell arrives continuously. That is, the next cell arrives at time ta = 2.
[0052]
At time ta = 2, TAT = 2 and τ = 0, and “ta = TAT−τ”, so that this arriving cell is also determined to be a compliant cell. Hereinafter, similarly, the VS algorithm outputs a similar determination result to each arriving cell.
[0053]
Thus, given the “minimum cell interval value T = 1” and “fluctuation absorption value τ = 0”, the VS algorithm regards all arriving cells as compliant cells. Therefore, assuming that the monitoring period = 5, if the UPC function is normal, it is expected that “the number of passing cells = 5” and “the number of discarded cells = 0”. These values are expected values when “T = 1” and “τ = 0” are used as test parameters.
[0054]
FIG. 7B shows a case where “minimum cell interval value T = 3” and “fluctuation absorption value τ = 0” are given as test parameters. In this case, if the interval between the arrival time of a certain cell and the arrival time of a cell before that cell is “3” or more, the VS algorithm determines that the arrival cell is a compliant cell and sets the interval to “3”. If it is smaller than "3", it is determined that the cell is a non-compliant cell.
[0055]
For example, if the cell arrives at time ta = 1 when the logical arrival time TAT is “1”, TAT = 1 and τ = 0 in step S1 of FIG. 4, and “ta = TAT-τ ”, the arrival cell is determined to be a compliant cell. Then, in step S3, a logical arrival time TAT of the next arrival cell is generated. Here, since “T = 3”, the increment value I becomes “3” in the flowchart of FIG. Therefore, “4” is generated as the logical arrival time TAT for the next arrival cell.
[0056]
Subsequently, when a cell arrives at time ta = 2, TAT = 4 and τ = 0 in step S1 of FIG. 4 and “ta <TAT−τ”, so that the arriving cell is determined to be a non-conforming cell. You. In this case, the logical arrival time TAT is not updated. Further, when a cell arrives at time ta = 3, the result of step S1 in FIG. 4 is also “Yes”, and the arrival cell is determined to be a non-compliant cell. Also in this case, the logical arrival time TAT is not updated.
[0057]
Thereafter, when a cell arrives at time ta = 4, TAT = 4 and τ = 0 in step S1 of FIG. 4 and “ta = TAT−τ”, so that the arriving cell is determined to be a compliant cell. . Thereafter, similarly, the VS algorithm repeatedly outputs the determination results at time ta = 1 to time ta = 3.
[0058]
As described above, when the “minimum cell interval value T = 3” is used as the test parameter, the VS algorithm basically determines one of the three arrived cells as the compliant cell and determines the other two cells as the compliant cell. Are determined as non-compliant cells. Therefore, assuming that the monitoring period = 15, if the UPC function is normal, it is expected that “the number of passing cells = 5” and “the number of discarded cells = 10”. These values are expected values when “T = 1” and “τ = 0” are used as test parameters.
[0059]
FIGS. 7A and 7B show an example in which “τ = 0” is given. However, if a value other than 0 is given as “fluctuation absorption value τ”, the calculation becomes slightly complicated. . Hereinafter, the results of the UPC calculation in the case where “minimum cell interval value T = 3” and “fluctuation absorption value τ = 1” are given as test parameters will be described with reference to FIG.
[0060]
Assuming that the cell arrives at time ta = 1 when the logical arrival time TAT is “1”, TAT = 1 and τ = 1 in step S1 of FIG. 4, and “ta> TAT− τ ”, the arrival cell is determined to be a compliant cell. Also, “4” is generated as the logical arrival time TAT of the next arrival cell. This processing is the same as the example in FIG.
[0061]
At time ta = 2, TAT = 4 and τ = 1 in step S1 of FIG. 4 and “ta <TAT−τ”, so that the arrival cell is determined to be a non-compliant cell. In this case, the logical arrival time TAT is not updated.
[0062]
At time ta = 3, since TAT = 4 and τ = 1 in step S1 of FIG. 4, “ta = TAT−τ”, and the arrival cell is determined to be a compliant cell. Also, the logical arrival time TAT of the next cell is “ta <TAT” at the time ta = 3, so “7” is obtained by TAT = TAT + T.
[0063]
As described above, when the fluctuation absorption value τ is used in the UPC calculation, a cell arriving at an interval shorter than the minimum cell interval value T may be determined as a compliant cell. However, in this case, in the VS algorithm, the logical arrival time TAT of the next cell is not calculated based on the current time (time ta), but is calculated based on the logical arrival time TAT of the cell. Is done.
[0064]
Subsequently, at time ta = 4, TAT = 7 and τ = 1 in step S1 of FIG. 4 and “ta <TAT−τ”, so that the arrival cell is determined to be a non-compliant cell. Even at time ta = 5, TAT = 7 and τ = 1 in step S1 of FIG. 4 and “ta <TAT−τ”, so that the arrival cell is determined to be a non-compliant cell. During this time, the logical arrival time TAT is not updated.
[0065]
Thereafter, at time ta = 6, since TAT = 7 and τ = 1 in step S1 in FIG. 4, “ta = TAT−τ”, and the arrival cell is determined to be a compliant cell. In addition, the logical arrival time TAT of the next cell is “10” by TAT = TAT + T. Thereafter, similarly, the VS algorithm repeatedly outputs the determination results at time ta = 4 to time ta = 6.
[0066]
FIG. 7C shows a determination result by the VS algorithm when “minimum cell interval value T = 3” and “fluctuation absorption value τ = 1” are given as test parameters. In this case, assuming that the monitoring period = 15, in the first monitoring period, “the number of passing cells = 6” and “the number of discarded cells = 9” are obtained due to the influence of the fluctuation absorption value τ. However, in the case of "T = 3", the ratio between the number of passing cells and the number of discarded cells is 1: 2, so that "the number of passing cells = 5" and "the number of discarded cells = 10" are obtained thereafter. . For this reason, if “6” and “9” are registered as “expected value of the number of passing cells” and “expected value of the number of discarded cells”, respectively, a correct judgment can be obtained in the first monitoring period. In the subsequent monitoring period, “abnormal” is detected in the determination by the passage measurement unit 6 and the discard measurement unit 7. On the other hand, if “5” and “10” are registered as “expected value of the number of passing cells” and “expected value of the number of discarded cells”, respectively, "Abnormal" will be detected during the first monitoring period.
[0067]
In order to avoid this situation, the present embodiment introduces the following configuration.
(1) The “expected value of the number of passing cells” and the “expected value of the number of discarded cells” use values determined by the “minimum cell interval value T” independently of the “fluctuation absorption value τ”.
(2) In the first monitoring period, the width of the window is shortened by the “fluctuation absorption value τ”.
(3) The discard measurement unit 7 compares a value obtained by adding the “fluctuation absorption value τ” to the “discarded cell number” obtained as a result of the determination of the VS algorithm during the first monitor period, and its expected value.
[0068]
The above (1) to (3) will be described with reference to an example shown in FIG. First, when “minimum cell interval value T = 3” and “fluctuation absorption value τ = 1” are used as test parameters, “expected value of passing cell number” and “expected value of discarded cell number” are respectively used. 5 ”and“ 10 ”are registered. In the first monitoring period, the width of the window is set to “14” by shortening the window by the “fluctuation absorption value τ”. As a result, the output of the VS algorithm during the first monitoring period is “number of passing cells = 5” and “number of discarded cells = 9”. Then, the discard measurement unit 7 adds “1” to “the number of discarded cells” obtained by counting the output of the VS algorithm during the first monitoring period to obtain “10”. As a result, in the first monitoring period, the corrected output of the VS algorithm matches the expected value.
[0069]
In the subsequent monitoring period, the above (2) and (3) are not executed. That is, the width of the window is “15”, and the “passing cell number” and “discarded cell number” obtained by counting the output of the VS algorithm are directly compared with their expected values.
[0070]
Here, a circuit configuration for realizing the above (2) and (3) will be described. FIG. 9 is a block diagram of the window generator 5. The window generation unit 5 defines a monitoring period for counting the “number of passing cells” and the “number of discarded cells” based on the “minimum cell interval value T” stored as a test parameter in the parameter storage memory 1. Generate The multiplier 11 multiplies the “minimum cell interval value T” by a constant n. For example, n = 10. The subtractor 12 subtracts the “fluctuation absorption value τ” from the output of the multiplier 11. The “fluctuation absorption value τ” is stored in the parameter storage memory 1 as a test parameter. The selection unit 13 selects the output of the subtraction unit 12 when there is an update notification from the rewrite detection unit 4, and selects the output of the multiplication unit 11 when there is no update notification. That is, immediately after the test parameters are rewritten, the output of the subtraction unit 12 is selected, and thereafter, the output of the multiplication unit 11 is selected.
[0071]
The counter 14 is incremented each time a cell Top signal is received from the timing generator 172. That is, the count value is incremented by one each time a cell arrives. The comparing unit 15 compares the output of the selecting unit 13 and the output of the counter 14, and when they match each other, outputs a window instruction signal and resets the counter 14.
[0072]
According to the above configuration, the window generation unit 5 outputs a signal indicating “window width = T · n−τ” immediately after the test parameter is rewritten, and thereafter, outputs the signal “window width = T · n−τ” until the test parameter is rewritten again. A signal representing “window width = T · n” is output.
[0073]
FIG. 10 is a block diagram of the passage measurement unit 6. The passage measurement unit 6 compares the number of cells determined as “compliant cells” by the UPC operation using the test parameters with its expected value, and checks the normality of the UPC operation based on the comparison result. The counter 21 is reset by the window instruction signal generated by the window generation unit 5, and counts the number of “passing notifications” given until the next window instruction signal. The counted value is given to the comparison unit 22.
[0074]
The “passing instruction” is a “passing / discarding instruction signal” which is a result of the UPC operation performed by the arithmetic unit 2. The "pass / discard instruction signal" indicates "1: pass" when the arrival cell is a compliant cell, and indicates "0: discard" when the arrival cell is a non-compliant cell. However, as described above, every time a cell arrives, the operation unit 2 executes the UPC operation for the connection transmitting the cell and the UPC operation for checking the UPC function. For this reason, the opening and closing of the gate 31 is controlled using the “switching instruction signal” so that only the result of the UPC operation for checking the UPC function is given to the passage measurement unit 6. The “switch instruction signal” is a signal indicating that the normal UPC operation has been completed in the operation unit 2. As a result, the counter 21 counts the number of cells determined as “compliant cells” in the window generated by the window generation unit 5 by the UPC operation using the test parameters.
[0075]
The comparing unit 22 compares the “expected value of the number of passing cells” stored in the parameter storage memory 1 with the output of the counter 21. That is, the comparison unit 22 compares the number of cells regarded as compliant cells by the calculation unit 2 with the expected value. If they match each other, a signal indicating that the UPC function is normal is sent to the result output unit 8. On the other hand, if they do not match each other, a signal indicating that the UPC function is abnormal is output. It is sent to the result output unit 8.
[0076]
FIG. 11 is a block diagram of the discard control unit 7. The discard control unit 7 compares the number of cells determined as “non-compliant cells” by the UPC operation using the test parameters with the expected value, and checks the normality of the UPC operation based on the comparison result.
[0077]
The counter 41 is basically the same as the counter 21 provided in the passage measurement unit 6. However, a “discard notification” is given to the counter 41 instead of the “pass notification”. The “discard notification” is obtained by ORing the inverted signal of the “pass / discard instruction signal” and the “switch instruction signal”.
[0078]
The adder 42 adds the “fluctuation absorption value τ” to the output of the counter 41. The “fluctuation absorption value τ” is stored in the parameter storage memory 1 as a test parameter. The selection unit 43 selects the output of the addition unit 42 when an update notification is received from the rewrite detection unit 4, and selects the output of the counter 41 when there is no update notification. That is, immediately after the test parameter is rewritten, the output of the adding unit 42 is selected, and thereafter, the output of the counter 41 is selected.
[0079]
The comparing unit 44 compares the “expected value of the number of discarded cells” stored in the parameter storage memory 1 with the output of the selecting unit 43. That is, immediately after the test parameter is rewritten, the comparison unit 44 calculates the value obtained by adding the “fluctuation absorption value τ” to the number of cells determined to be a non-compliant cell by the calculation unit 2 and the “discarded cell count”. , And thereafter, the number of cells regarded as non-compliant cells by the operation unit 2 is compared with the “expected value of the number of discarded cells”. If they match each other, a signal indicating that the UPC function is normal is sent to the result output unit 8. If they do not match each other, a signal indicating that the UPC function is abnormal is output as the result. It is sent to the unit 8.
[0080]
When receiving a signal indicating an abnormality from at least one of the passage measurement unit 6 and the discard measurement unit 7, the result output unit 8 outputs a signal indicating that a failure has occurred in the calculation unit 2 or its surroundings. Output.
[0081]
FIG. 12 is a diagram illustrating generation of a window in consideration of the fluctuation absorption value τ and correction of the number of discarded cells. Here, the minimum cell interval value T is “3”. The value multiplied by the multiplication unit 11 of the window generation unit 5 is “10”. As a result, the width of the window generated by the window generation unit 5 is basically “30”. Further, since “T = 3”, “10” and “20” are registered as “expected value of the number of passing cells” and “expected value of the number of discarded cells”, respectively. FIG. 12 shows the operation immediately after the test parameters in the parameter storage memory 1 are rewritten.
[0082]
When “τ = 0”, the window generation unit 5 always generates a window having a width of “30”. Further, the result of the UPC operation using the test parameters (T = 3, τ = 0) is “number of compliant cells = 10” and “number of non-compliant cells = 20”, assuming that the UPC function is normal. The “number of compliant cells” obtained as a result of the UPC operation matches the “expected value of the number of passing cells”, and the “number of non-compliant cells” and the “number of discarded cells” obtained as a result of the UPC operation Are equal to each other, it is determined that the UPC function is normal. On the other hand, when the result of the UPC operation is “number of compliant cells セ ル 10” or “number of non-compliant cells ≠ 20”, it is determined that the UPC function is abnormal.
[0083]
If “τ = 1”, the window generating unit 5 first generates one window having a width of “29” as the first window. In this first window, the results of the UPC operation using the test parameters (T = 3, τ = 1) are “the number of compliant cells = 10” and “the number of non-compliant cells”, assuming that the UPC function is normal. = 19 ". In the first window, the discard measurement unit 7 adds the “fluctuation absorption value τ” to the “number of non-compliant cells” obtained as a result of the UPC operation. The result of this addition is "20". Then, the “number of compliant cells” obtained as a result of the UPC operation matches the “expected value of the number of passing cells”, and the correction value of the “number of non-compliant cells” obtained as a result of the UPC operation and the “discard” If the “expected value of the number of cells” matches each other, it is determined that the UPC function is normal. On the other hand, when the result of the UPC operation is “number of compliant cells ≠ 10” or “number of non-compliant cells ≠ 19”, it is determined that the UPC function is abnormal.
[0084]
The operation in the second window and the subsequent operation are the same as the operation in the case of “τ = 0”. That is, the window generation unit 5 generates a window having a width of “30”. Further, the discard measurement unit 7 does not perform the correction using the “fluctuation absorption value τ”. Then, the normality of the UPC function is determined in the same manner as in the case of “τ = 0”.
[0085]
The operation when “τ = 2” and the case when “τ = 3” are basically the same as the operation when “τ = 1”. However, when “τ = 2”, the window generation unit 5 generates a window having a width of “28” as the first window. Further, the discard measurement unit 7 adds “2” to “the number of non-compliant cells” obtained as a result of the UPC operation in the first window, and compares the addition result with “the expected value of the number of discarded cells”. . On the other hand, when “τ = 3”, the window generating unit 5 generates a window having a width of “27” as the first window. Further, the discard measurement unit 7 adds “3” to “the number of non-compliant cells” obtained as a result of the UPC operation in the first window, and compares the addition result with “the expected value of the number of discarded cells”.
[0086]
Next, the overall operation of the UPC section shown in FIG. 1 will be described with reference to a time chart.
[0087]
FIG. 13 is a time chart when the minimum cell interval value T is “1”, the fluctuation absorption value τ is “0”, and the window width is “10”. In this case, “10” and “0” are registered as “expected value of the number of passing cells” and “expected value of the number of discarded cells”, respectively. FIG. 13 shows the operation immediately after the test parameters in the parameter storage memory 1 are rewritten.
[0088]
The arriving cell is provided to the delay unit 171, the timing generation unit 172, and the cell identification unit 173. The delay unit 171 holds the cell for a predetermined time and then passes it to the discard control unit 177, and the timing generation unit 172 generates a cell Top signal every time a cell arrives. Then, the counter 14 of the window generator 5 is counted up by the cell Top signal.
[0089]
The operation unit 2 recognizes a user address corresponding to VPI / VCI of the arrival cell, and extracts necessary parameters from the parameter storage memory 1 using the user address as a key. Then, using the extracted parameters, the operation unit 2 determines whether the arrival cell is a compliant cell or a non-compliant cell, and notifies the discard control unit 177 of the result. This processing is executed in the “operation range”. If the arrival cell is a compliant cell, the discard control unit 177 passes the cell. If the arrival cell is a non-compliant cell, the discard control unit 177 discards the cell.
[0090]
When this processing is completed, the operation unit 2 outputs a switching instruction signal to read out the test parameters from the parameter storage memory 1. Upon receiving the switching instruction signal, the address selection unit 3 instructs a test address, and the parameter storage memory 1 provides a test parameter to the arithmetic unit 2 according to the instruction. Then, the arithmetic unit 2 determines whether the arrival cell is a compliant cell or a non-compliant cell using the given test parameters, and notifies the result to the passage measurement unit 6 and the discard measurement unit 7. . This process is executed in the “failure Check range”.
[0091]
Upon receiving the notification that the arrival cell is a compliant cell (pass notification in FIG. 10), the passage measurement unit 6 counts up the counter 21. On the other hand, upon receiving the notification that the arrival cell is a non-compliant cell (discard notification in FIG. 11), the discard measurement unit 7 counts up the counter 41.
[0092]
The above operation is repeated every time a cell arrives. When the count value of the counter 14 of the window generation unit 5 reaches a value indicating the window width, that is, when the end timing of the window is reached, the passage measurement unit 6 and the discard measurement The comparison processing is executed in each of the units 7. That is, the passage measurement unit 6 compares the count value of the counter 21 with the “expected value of the number of passage cells” stored in the parameter storage memory 1, and if they match each other, the UPC function is normal. Judge that there is. Similarly, the discard measuring unit 7 compares the count value of the counter 41 with the “expected value of the discarded cell number” stored in the parameter storage memory 1, and if they match each other, the UPC function is normal. Is determined.
[0093]
FIG. 14 is a time chart when the minimum cell interval value T is “3”, the fluctuation absorption value τ is “1”, and the window width is “30”. Here, a case is shown in which the results of the UPC operation for cells 3 to 5 are “compliant”, “non-compliant”, and “non-compliant”, respectively.
[0094]
When it is determined that the cell 3 is a compliant cell, a “pass notification” is given to the passage measuring unit 6 and the counter 21 of the passage measuring unit 6 is counted up. On the other hand, when it is determined that the cells 4 and 5 are non-compliant cells, a “discard notification” is given to the discard measuring unit 7 and the counter 41 of the discard measuring unit 7 is counted up.
[0095]
In the above embodiment, when the fluctuation absorption value τ is not “0”, the error of the error is corrected by adjusting the width of the first window after the test parameters are updated and correcting the number of discarded cells. Although the occurrence is avoided, it is also possible to avoid the error by other methods. For example, for a set of test parameters, an expected value for the first window and an expected value for the second and subsequent windows are registered, and the expected values are selected as necessary. May be. For example, in the example shown in FIG. 12, when “T = 3” and “τ = 1”, “expected value of the number of passing cells = 11” and “expected value of the number of discarded cells” for the first window. = 19 "and" expected value of the number of passing cells = 10 "and" expected value of the number of discarded cells = 20 "may be registered for the second and subsequent windows. With this configuration, there is no need to adjust the window width or correct the number of discarded cells.
[0096]
In the above embodiment, only one set of test parameters is registered, but a plurality of sets of test parameters can be registered in the parameter storage memory 1 as shown in FIG. If this configuration is introduced, the normality of the UPC function can be checked for various parameters without updating the parameter storage memory 1.
[0097]
By the way, if the window generation unit 5, the passage measurement unit 6, or the discard measurement unit 7 is out of order, information indicating "abnormal" may not be output even though the UPC function is out of order. . According to the present embodiment, in order to avoid this problem, it is also possible to check whether the function itself for detecting and notifying the abnormality of the UPC function is operating normally.
[0098]
For example, an incorrect value is intentionally registered as the “expected value of the number of passing cells” or the “expected value of the number of discarded cells”. In this case, if the UPC function and the function for detecting and notifying the abnormality of the UPC function are normal, information indicating "abnormal" should be output. Therefore, it is necessary to check whether information indicating "abnormal" is output with a wrong value intentionally registered as "expected value of the number of passing cells" or "expected value of the number of discarded cells". Thus, the normality of the function for detecting and notifying the abnormality of the UPC function can be checked.
[0099]
Further, in the present embodiment, the minimum cell interval value registered as a test parameter is multiplied by n to set a monitor period for counting the number of passed cells and the number of discarded cells. By doing so, desired parameters can be used. For example, if “n = 10”, a decimal value can be used as the minimum cell interval value for testing.
[0100]
【The invention's effect】
According to the present invention, in a fixed-length packet network, a failure in the function of controlling traffic can be detected without using a test packet, so that efficiency is improved. Further, it is possible to detect a failure in the function of controlling traffic using desired parameters, which is useful for failure prediction and analysis.
[Brief description of the drawings]
FIG. 1 is a block diagram of a UPC section according to the present embodiment.
FIG. 2 is a diagram schematically illustrating an example of a parameter storage memory.
FIG. 3 is a diagram illustrating a minimum cell interval value and a fluctuation absorption value.
FIG. 4 is a flowchart of a basic process of a virtual scheduling algorithm.
FIG. 5 is a diagram illustrating the operation timing of a calculation unit.
FIG. 6 is a diagram for explaining a basic operation of the UPC section.
FIG. 7 is a diagram illustrating an example of an output that would be obtained as a result of a UPC operation if the operation unit was normal;
FIG. 8 is a diagram illustrating a VS algorithm.
FIG. 9 is a block diagram of a window generation unit.
FIG. 10 is a block diagram of a passage measurement unit.
FIG. 11 is a block diagram of a discard measurement unit.
FIG. 12 is a diagram illustrating generation of a window in consideration of a fluctuation absorption value and correction of the number of discarded cells.
FIG. 13 is a time chart (No. 1) showing an overall operation of the UPC section of the embodiment.
FIG. 14 is a time chart (part 2) illustrating the overall operation of the UPC section of the embodiment.
FIG. 15 is a diagram showing a memory for storing a plurality of test parameters.
FIG. 16 is a diagram showing a configuration of an ATM network.
FIG. 17 is a block diagram of a UPC device.
FIG. 18 is a block diagram illustrating an example of an existing UPC unit.
[Explanation of symbols]
1 Parameter storage memory
2 Operation part
3 Address selection section
4 Rewriting detector
5 Window generator
6 Passage measurement unit
7 Disposal measurement section
11 Multiplication unit
12 Subtraction unit
14 counter
21 Counter
41 counter
42 Adder
172 Timing generator
172 Cell identification unit
177 Discard control unit

Claims (10)

An apparatus for judging the normality of a function of controlling traffic of a fixed-length packet in a network transmitting the fixed-length packet,
Storage means for storing a parameter for checking the normality of the function of controlling the traffic of the fixed-length packet,
Each time a fixed-length packet arrives, a UPC is performed using a parameter set for a connection corresponding to the fixed-length packet during a first period within a unit time allocated to the fixed-length packet. Calculating means for performing an operation and performing a UPC operation using a parameter stored in the storage means during a second period within the unit time;
Judging means for judging normality of a function of controlling traffic of the fixed-length packet based on a result of the UPC operation by the arithmetic means in the second period;
Device for judging the normality of the function of controlling traffic having 2. The apparatus according to claim 1, wherein the storage unit is a rewritable storage area, and a desired value can be set as the parameter. The apparatus according to claim 1, wherein a plurality of parameters are stored in the storage unit, and the calculation unit performs the UPC operation using one of the plurality of parameters during the second period. The parameter stored in the storage means is a value indicating the arrival interval of fixed-length packets,
The UPC operation by the arithmetic means is a process for determining whether the arrived fixed-length packet is a compliant packet or a non-compliant packet.
The determining means is
Window generation means for generating a window defining a period determined based on the parameters stored in the storage means,
Counting means for counting the number of compliant packets and the number of non-compliant packets detected in the plurality of second periods existing in the window,
Each expected value of the number of compliant packets and the number of non-compliant packets that would be detected in the window by the counting means if the UPC operation was performed using the parameters, and the compliant number counted by the counting means. A comparison that compares the number of packets and the number of non-compliant packets, respectively, and outputs information indicating that the function of controlling traffic of fixed-length packets is abnormal when at least one of them does not match. Means,
The device of claim 1 comprising: 5. The apparatus according to claim 4, wherein said window generation means generates a window by multiplying an interval represented by a parameter stored in said storage means by an integer. The apparatus according to claim 4, wherein information indicating that the function of controlling traffic of fixed-length packets is abnormal is forcibly output by intentionally using an incorrect value as the expected value. The storage means stores a first parameter indicating an arrival interval of fixed-length packets and a second parameter indicating delay variation.
The UPC operation by the arithmetic means is a process for determining whether the arrived fixed-length packet is a compliant packet or a non-compliant packet.
The determining means is
Window generation means for generating a window defining a period determined based on the first and second parameters stored in the storage means;
Counting means for counting the number of compliant packets and the number of non-compliant packets detected in the plurality of second periods existing in the window,
The expected value of the number of compliant packets and the number of non-compliant packets that would be detected in the window by the counting means if the UPC operation was performed using the first and second parameters; The number of compliant packets and the number of non-compliant packets counted by the means are compared with each other, and when at least one of them does not match, the function of controlling the traffic of the fixed-length packet is abnormal. Comparing means for outputting information representing the information;
The device of claim 1 comprising: The window generating means generates a window by subtracting the delay variation from a value obtained by multiplying the arrival interval by an integer when a parameter stored in the storage means is changed,
The said comparison means, when a parameter stored in the storage means is changed, compares a value obtained by adding the delay variation to the number of non-compliant packets counted by the counting means and the expected value. An apparatus according to claim 7. An apparatus for judging the normality of a function of controlling traffic of a fixed-length packet in a network transmitting the fixed-length packet,
Calculating means for performing a first UPC operation and a second UPC operation on the fixed-length packet each time the fixed-length packet arrives;
Discarding control means for determining whether to discard the fixed-length packet based on the result of the first UPC calculation by the calculating means;
Determining means for determining the normality of the operation of the calculating means based on a result of the second UPC calculation by the calculating means;
Device for judging the normality of the function of controlling traffic having A method for determining the normality of a function of controlling traffic of a fixed-length packet in a network transmitting the fixed-length packet,
Storing a parameter for checking the normality of the function of controlling the traffic of the fixed-length packet;
Each time a fixed-length packet arrives, a UPC is performed using a parameter set for a connection corresponding to the fixed-length packet during a first period within a unit time allocated to the fixed-length packet. Performing an operation and performing a UPC operation using the parameter during a second time period within the unit time;
Judging the normality of the function of controlling the traffic of the fixed-length packet based on the result of the UPC operation in the second period;
A method for determining the normality of a function for controlling traffic having the following.

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