JP3646871B2 - Data relay apparatus and data relay method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cell discard control technique in the case where, for example, a buffer for temporarily storing ATM cells is included, cells excessively flow into the buffer, and the buffer overflows to discard cells.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an ATM switch is a device that accumulates cells in a buffer and may cause excessive flow of cells into the buffer. For example, an output buffer type switch is a switch having a buffer for each outgoing line.
[0003]
FIG. 11 shows an output buffer type ATM switch having four incoming lines and four outgoing lines. In FIG. 11, 200 is an output buffer type ATM switch, 100 is a buffer for storing cells, and 300 is a distribution circuit.
The cell input from the incoming line is distributed to the destination outgoing line by the distribution circuit 300 in the first half of the switch 200 and written to the buffer 100 corresponding to the outgoing line. On the outgoing line side, one cell is read from the buffer 100 per one cell time (if no cells are accumulated, an idle cell is output).
[0004]
FIG. 12 is a diagram for explaining the operation of the output buffer type switch 200. In the output buffer type switch 200, when inputs from different incoming lines are concentrated on the same outgoing line, the output buffer type switch 200 generally writes to the buffer from the youngest number of incoming lines. In the case of FIG. 12, cells are queued in the order of incoming lines # 1, # 2, # 3, and # 4, and the cells corresponding to incoming line # 1 are output in order. In the case of 4 incoming lines, a maximum of 4 cells are input simultaneously.
[0005]
Since reading from the outgoing line is one cell per one cell time, if cells from a plurality of incoming lines are concentrated for a long time with respect to a specific outgoing line, the buffer overflows. At this time, the following problems occur in the control of queuing from the incoming line number.
[0006]
FIG. 13 shows only the buffer portion of the outgoing line # 1 shown in FIG. As shown in FIG. 13, in the buffer full state, when a cell is always input from the incoming lines # 1 to # 4 to the outgoing line # 1, one cell is read from the buffer every cell time, Four cells are input.
Since one cell is vacant when one cell is read, the cell of incoming line # 1 is written when the method of writing from a young number is used, but the cells of incoming lines # 2 to # 4 are buffered when # 1 is written. Because it becomes full, it is discarded without being able to write. Similarly, at the next cell time, one cell is read from the buffer, and only the cell of the incoming line # 1 is written. If this state continues, only cell # 1 is written into the buffer. This indicates that unfairness occurs between incoming lines.
[0007]
Conventionally, there is a method called incoming line rotation as a method for preventing unfairness between incoming lines. This is a method of rotating the priority order of writing in units of one cell time, instead of always performing the writing order to the buffer from the young incoming line.
For example, when the number of incoming lines is 4, writing is performed with the following priority every 4 cell times.
Cell time 1: # 1 → # 2 → # 3 → # 4
(If there is a cell from incoming line # 1, write it, if not, write cell # 2, otherwise write cell # 3, otherwise write cell # 4.)
Cell time 2: # 2 → # 3 → # 4 → # 1
Cell time 3: # 3 → # 4 → # 1 → # 2
Cell time 4: # 4 → # 1 → # 2 → # 3
Thereafter, the method shown in the cell time 1 to the cell time 4 is repeated.
[0008]
The operation of incoming line rotation will be described with reference to FIG.
When one cell is read from the buffer full state and one cell is available, if the first priority of the incoming line rotation is incoming line # 1, the incoming line # 1 cell is written and becomes buffer full, and incoming lines # 2 to # 4. Cells are discarded. In the next cell time, since the first priority of the incoming line rotation is incoming line # 2, the cell of incoming line # 2 is written. Similarly, cells of incoming line # 3 and incoming line # 4 are written after one cell time elapses. That is, cells of incoming lines # 1 to # 4 are written to the buffer fairly.
[0009]
However, in order to realize the incoming line rotation, it is necessary to store the rotation information (first priority incoming line number), and the complicated control of sequentially writing the cells to the buffer from the first priority incoming line that changes every cell time. Is required.
[0010]
On the other hand, also in the shaping device, as in the case of the ATM switch, when the input bandwidth is larger than the output bandwidth, unfairness occurs regarding cell discard between connections.
[0011]
A conventional shaping apparatus will be described with reference to FIG. In FIG. 15, reference numeral 400 denotes a shaping device, and 100 denotes a shaping buffer. The shaping apparatus 400 of FIG. 15 is an apparatus that temporarily stores cells of a plurality of connections in one buffer 100 and reads the cells at a constant speed (shaping speed).
[0012]
In FIG. 15, it is assumed that cells of VP / VC = A, B, and C are regularly input at a rate of 50 Mb / s, that is, a total of 150 Mb / s and read from the buffer 100 at a rate of 50 Mb / s. . In this case, the buffer becomes full immediately. Even in the buffer full state, data is read out at a speed of 50 Mb / s and inputted at a speed of 150 Mb / s, so that three cells are inputted while one cell is read out.
[0013]
For example, when a cell of VP / VC = A is input after one cell is read from the buffer full state, the A cell is written and becomes buffer full, and when the B and C cells are input, the buffer is full. Is discarded. Then, after one cell is read from the buffer, the A cell is input, so the A cell is written. Since this is repeated thereafter, only a specific VP / VC is written in the buffer. That is, when excessive traffic flows through the shaping device, unfairness occurs between connections.
[0014]
As another prior art of the cell discard control method, there is a priority control circuit disclosed in JP-A-11-55278. FIG. 16 is a diagram showing the configuration of the priority control circuit.
In FIG. 16, reference numeral 500 denotes a priority control circuit for performing priority control for giving priority to traffic A and B cells having different quality requirements, 100 denotes a single buffer capable of setting a plurality of threshold values, and 600 denotes a buffer. A read control circuit for controlling cell read from 100, and a control circuit 700 for performing different control for each threshold value.
[0015]
The buffer 100 has a threshold (1) for starting rate control for traffic A, a threshold (2) for starting cell discard for traffic B, and a threshold for canceling rate control for traffic A. There is a value (3) and a threshold value (4) for canceling cell discard for traffic B. As described above, the prior art performs threshold control for cell discard, and has a threshold for each different service class, and aims to perform priority control between service classes. It is not intended for cell discard control without being conscious of the same class or service class, and a threshold must be provided for each service class.
[0016]
[Problems to be solved by the invention]
The conventional cell discard control method performs simple control of discarding an overflow cell when the buffer overflows as described above. Therefore, regarding the cell discard, there is a problem that unfairness occurs between incoming lines in the case of an ATM switch, and unfairness between connections occurs in a shaping device.
In addition, cell discard control using a threshold value has been proposed, but this is a cell discard control method when cells of different service classes are input to the same buffer, and is conscious of the same service class or service class. It was not a cell discard control method. Also, it did not prevent the unfairness of cell discard between connections in the same service class.
The above-mentioned unfairness problem occurs when cells are excessively input to the buffer. Of course, when cells are always input at a low load (when cell discard does not occur), the problem does not occur. Does not occur.
[0017]
The present invention has been made to solve such a problem, and relates to cell discard control when cells of different connections are input to a single buffer without being conscious of the service class. Or it prevents the unfairness of cell discard between incoming lines.
[0018]
[Means for Solving the Problems]
The data relay device according to the present invention is:
Data relay that receives transmission data transmitted from the data transmission device, temporarily accumulates the received transmission data, and discards the received transmission data when the accumulated amount of transmission data exceeds a certain amount A device,
A data receiving unit for receiving transmission data transmitted from the data transmitting device;
A buffer unit for temporarily storing transmission data received by the data receiving unit;
An accumulated amount measuring unit for measuring an accumulated amount of accumulated transmission data accumulated in the buffer unit;
A transmission data discarding unit for discarding transmission data received by the data receiving unit based on the measurement result of the accumulated amount measuring unit;
A discard start threshold value setting unit that sets a discard start threshold value that is an accumulated amount of accumulated transmission data from which the transmission data discard unit starts discarding transmission data received by the data receiving unit;
A discard stop threshold for setting a discard stop threshold, which is an accumulated amount of stored transmission data equal to or less than the discard start threshold, in which the transmission data discarding unit stops discarding transmission data received by the data receiving unit. A value setting unit,
The transmission data discard unit
When the accumulated amount of accumulated transmission data measured by the accumulated amount measuring unit reaches the discard start threshold set by the discard start threshold setting unit, the accumulated amount of the accumulated transmission data becomes the discard After the start threshold value is reached, the transmission data received by the data receiving unit starts to be discarded, and the accumulated amount of accumulated transmission data measured by the accumulated amount measuring unit is set by the discard stop threshold value setting unit The transmission data received by the data receiving unit is stopped when it is reduced to the discarded threshold value.
[0019]
The discard start threshold value setting unit sets the discard start threshold value based on a predetermined level of the allowable storage amount of the buffer unit.
[0020]
The data receiving unit receives transmission data from at least one data transmission device via at least one communication path,
The discard stop threshold setting unit sets the discard stop threshold based on the number of communication channels.
[0021]
The data receiving unit receives transmission data of the same amount of data from each of at least one or more data transmission devices,
The discard start threshold value setting unit sets the maximum accumulation allowable amount of the buffer unit to the discard start threshold value,
The discard stop threshold value setting unit subtracts a value obtained by subtracting a value obtained by multiplying the data amount of the transmission data from the number of communication paths from the maximum accumulation allowable amount of the buffer unit from the discard stop threshold. It is characterized by being set to a value.
[0022]
The data relay device is an output buffer type ATM (Asynchronous Transfer Mode) switch device.
[0023]
The data relay device is a shaping device that receives an ATM (Asynchronous Transfer Mode) cell.
[0024]
The data relay method according to the present invention includes:
Data relay that receives transmission data transmitted from the data transmission device, temporarily accumulates the received transmission data, and discards the received transmission data when the accumulated amount of transmission data exceeds a certain amount A method,
A data reception step of receiving transmission data transmitted from the data transmission device;
An accumulation step for temporarily accumulating transmission data received in the data reception step;
An accumulation amount measuring step for measuring an accumulation amount of the accumulated transmission data accumulated by the accumulation step;
A transmission data discarding step for discarding the transmission data received by the data receiving step based on the measurement result of the accumulated amount measuring step;
A discard start threshold setting step for setting a discard start threshold that is an accumulation amount of accumulated transmission data in which the transmission data discarding step starts discarding the transmission data received by the data receiving step;
A discard stop threshold for setting a discard stop threshold value, which is an accumulated amount of stored transmission data equal to or less than the discard start threshold value, wherein the transmission data discarding step stops discarding the transmission data received by the data receiving step. A value setting step,
The transmission data discarding step includes:
When the accumulated amount of accumulated transmission data measured by the accumulated amount measuring step reaches the discard start threshold set by the discard start threshold setting step, the accumulated amount of the accumulated transmission data becomes the discard After reaching the start threshold, discard of the transmission data received by the data reception step is started, and the accumulated amount of accumulated transmission data measured by the accumulated amount measuring step is set by the discard stop threshold setting step The transmission data received by the data receiving step is stopped when the data is reduced to the discarded threshold value.
[0025]
The discard start threshold value setting step is characterized in that the discard start threshold value is set based on a predetermined level in the accumulation allowable amount of the accumulation step.
[0026]
The data receiving step receives transmission data from at least one data transmission device via at least one communication path,
In the discard stop threshold setting step, the discard stop threshold is set based on the number of the communication paths.
[0027]
The data reception step receives transmission data of the same amount of data from each of at least one data transmission device,
The discard start threshold setting step sets a maximum accumulation allowable amount of the accumulation step to the discard start threshold,
In the discard stop threshold setting step, a value obtained by subtracting a value obtained by multiplying the data amount of the transmission data by the number of communication channels from the maximum storage allowable amount in the storage step is the discard stop threshold. It is characterized by being set to a value.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a block diagram showing an embodiment of a data relay apparatus according to the present invention.
In FIG. 1, 10 is a 4-input / 4-output buffered ATM switch (data relay device), 2 is a cell receiving unit (data receiving unit) that receives a cell from the incoming line, 3 is a distribution circuit, and 1 is a cell storage It is a buffer to do.
Reference numeral 4 denotes a cell discard unit (transmission data discard unit) that discards cells received by the cell receiver.
Reference numeral 5 denotes a discard start threshold value setting unit for setting a threshold value (discard start threshold value) for the cell discard unit 4 to start discarding a cell. A predetermined storage amount among the storage amounts stored in the storage cell is set as a discard start threshold value.
Reference numeral 6 denotes a discard cancellation threshold value setting unit for setting a threshold value (discard cancellation threshold value) for the cell discard unit 4 that has started cell discarding to stop discarding cells. The setting unit 6 sets a predetermined accumulation amount among the accumulation amounts of the accumulation cells accumulated in the buffer 1 as a discard cancellation threshold value.
Reference numeral 7 denotes an accumulation amount measurement unit that measures the accumulation amount of the accumulation cells accumulated in the buffer 1 and determines whether or not to discard the cell based on the measurement result.
Before starting cell reception, the discard start threshold value setting unit 5 and the discard release threshold value setting unit 6 set the discard start threshold value and the discard release threshold value for the cell accumulation amount in the buffer 1. Is done.
[0029]
FIG. 2 shows a flowchart of the cell discard control process of the ATM switch 10 of FIG.
First, in step S1, the bit of the cell discard state of the accumulation amount measuring unit 7 is set to “0” as an initial value.
Next, when the cell receiving unit 2 receives the cell in step S2, the accumulated amount measuring unit 7 looks at the value of the bit in the cell discarding state in step S3. It is determined whether the inner cell accumulation amount is equal to or less than the discard cancellation threshold.
If the cell accumulation amount in the buffer is equal to or less than the discard cancellation threshold, the distribution circuit 3 writes the cell in a predetermined buffer (step S9), and the accumulation amount measurement unit 7 sets the cell discard state bit to “0” (step S9). Step S10).
If the cell accumulation amount in the buffer is larger than the discard cancellation threshold, the cell discard unit 4 discards the cell (step S11).
[0030]
In step S3, the accumulated amount measuring unit 7 looks at the value of the bit in the cell discarding state.
When the cell accumulation amount in the buffer is equal to or greater than the discard start threshold, the cell discard unit 4 discards the cell (step S5), and the accumulation amount measurement unit 7 sets the cell discard state bit to “1” (step S6). ). If the cell accumulation amount in the buffer is smaller than the discard start threshold value, the distribution circuit 3 writes the cell in a predetermined buffer (step S7). Since the cell time cell is read from the buffer 1, the received cell is discarded under the condition of step S8 even if the received cell arrives after the cell discard state bit becomes “1” (step S6). If so (step S11), the cells in the buffer are always reduced to the discard cancellation threshold after a certain period of time.
[0031]
As can be seen from the above description, the relationship between the discard start threshold value and the discard release threshold value is necessary for the two threshold values for performing this cell discard control. In addition, since the cells do not accumulate beyond the discard start threshold, it is good from the viewpoint of effective use of the buffer to keep the discard start threshold equal to the buffer size. There is no need to keep it. Conversely, by making the discard start threshold value smaller than the buffer size, it is possible to make the buffer size appear smaller than the actual buffer.
[0032]
In FIG. 1, the detailed operation of the cell discard control process when the overload traffic in which all the incoming cells are concentrated to the outgoing line # 1 flows will be described.
Here, the discard start threshold setting unit 5 sets the discard start threshold to the same value as the buffer size (maximum storage allowable amount), and the discard release threshold setting unit 6 inputs the discard release threshold from the buffer size. A value obtained by subtracting 4 from the number (buffer size−number of incoming lines (4) × cell data amount) is set.
3 to 5 show only the buffer portion of the output line # 1 in FIG. 1. As shown in FIG. 3, there are 4 cells input per cell time and 1 cell is read out. Assume that the buffer becomes full before three A1, B1, C1, and D1 cells arrive.
When the cells A1, B1, C1, and D1 are input, the accumulation amount measuring unit 7 determines that the cell accumulation amount in the buffer is equal to the discard start threshold value, and therefore, as shown in FIG. 4, A1, B1 , C1, and D1 cells are all discarded by the cell discard unit 4 to be in a cell discard state. In addition, one cell is read from the buffer 1 and one cell is vacant.
[0033]
In FIG. 4, at the time when cells A2, B2, C2, and D2 are input, in the cell discard state, the amount of accumulated cells in the buffer exceeds the discard release threshold, so all cells A2 to D2 Discarded.
In addition, one cell is read from the buffer 1 to generate a total of two cells. Similarly, the cells A3, B3, C3, and D3 are also discarded, and one cell is read to generate a total of three cells, and the cells A4, B4, C4, and D4 are also discarded, and one cell is read and summed. A space of 4 cells is generated and the state shown in FIG. 5 is obtained.
[0034]
In FIG. 5, since the cell accumulation amount in the buffer is the same value as the discard cancellation threshold value, the cell discard state is canceled, and the cells A5, B5, C5, and D5 are written in the buffer 1 as shown in FIG. It is. Therefore, all incoming cells are written fairly during this time. This can be realized by setting the discard cancellation threshold value to a value obtained by subtracting 4 from the discard start threshold, which is the same as the number of incoming lines.
[0035]
As described above, the ATM switch according to the present embodiment ensures the fairness of cell discard between incoming lines. That is, there is an effect that unfairness between incoming lines can be prevented without performing incoming line rotation.
In-line rotation needs to be stored in a priority order by rotation and written to the buffer according to the priority order that changes every cell time, and the circuit becomes complicated, but this ATM switch has two threshold values. It has the effect that it can be realized with a simple circuit.
[0036]
In addition, by making the discard start threshold value coincide with the buffer size, the buffer can be used as effectively as possible.
[0037]
Embodiment 2. FIG.
FIG. 7 is a block diagram showing an embodiment of a data relay apparatus according to the present invention.
7, 20 is a shaping device, and 1, 2, and 4 to 7 are the same as in FIG. 1, 1 is a buffer, 2 is a cell receiving unit, 4 is a cell discarding unit, and 5 is a discard start threshold. A setting unit, 6 is a discard cancellation threshold value setting unit, and 7 is an accumulation amount measuring unit.
As in the first embodiment, the discard start threshold value setting unit 5 and the discard release threshold value setting unit 6 set the discard start threshold value and the discard release threshold value for the cell accumulation amount in the buffer 1. Is done. The relationship between the two threshold values is the discard start threshold value> the discard release threshold value. In FIG. 7, the discard start threshold value = buffer size.
The cells of various connections are input to the buffer 1 at the total speed B, and the cells are read at a certain constant speed A. In general, the speed B is not limited to a constant speed but varies with time.
[0038]
If the reading speed A and the input speed B from the buffer 1 are B ≦ A, no cells are accumulated in the buffer 1 and it is not necessary to discard the cells. If B> A, cells start to accumulate in the buffer 1, and if the time B> A continues for a certain amount of time, the buffer overflows and cells need to be discarded.
The present invention relates to cell discard control under such circumstances.
[0039]
It is assumed that the cells in the buffer 1 are accumulated up to the discard start threshold due to the relationship between the input speed B to the buffer 1 and the output speed A from the buffer 1, and a new cell arrives in that state. At this time, the cell is discarded, and subsequently input cells are discarded until the cells in the buffer are reduced to the discard release threshold.
Since data is read from the buffer 1 at a constant speed A, if cells continue to be discarded after the cells have accumulated up to the discard start threshold value, the buffer must be buffered up to the discard release threshold value after a certain period of time. The number of cells inside decreases. When a new cell arrives in a state reduced to the discard release threshold, the cell is written into the buffer 1 and then the cell is written until the cell in the buffer 1 increases to the discard start threshold. Thereafter, the same cell discard control as described above is performed.
[0040]
The operation of cell discard control will be described in detail using a specific example.
In the following, it is assumed that cells of VP / VC = A, B, C are sequentially input to the buffer 1 and the input speed V is higher than the read speed W. Further, the discard start threshold value is made to coincide with the buffer size, and the discard release threshold value is set to a value smaller by 3 cells than the buffer size. The value of 3 cells is set because three VP / VCs are input.
[0041]
In FIG. 7, it is assumed that the speed V is three times the speed W, and the buffer full state is reached when the cell A1 arrives.
When the A1 cell arrives, the accumulation amount measuring unit 7 determines that the in-buffer cell accumulation amount matches the discard start threshold value, so the A1 cell is discarded by the cell discard unit 4, and cell discarding is performed. It becomes a state.
Since one cell is read every time three cells are input due to the relationship between the speeds V and W, as shown in FIG. 8, after three cells A1, B1, and C1 are discarded, one cell is read and stored in the buffer. One cell is generated and the state shown in FIG. 8 is obtained.
[0042]
When the cells A2, B2, and C2 arrive, there is only one cell in the buffer 1 and the cell accumulation amount in the buffer is larger than the discard release threshold value, so these cells are discarded. Thereafter, the cell is read from the buffer 1, and the empty space in the buffer 1 becomes 2 cells. Similarly, when cells A3, B3, and C3 arrive, there are only two cells in the buffer 1 and the accumulated amount of cells in the buffer is larger than the discard release threshold, so these cells are discarded. Thereafter, the cells are read from the buffer 1, and the vacant space in the buffer 1 becomes 3 cells, and the state shown in FIG. 9 is obtained.
[0043]
When the A4 cell arrives in the state shown in FIG. 9, the accumulation amount measuring unit 7 determines that the cell accumulation amount in the buffer is equal to or less than the discard cancellation threshold value. The state is released.
When the B4 cell arrives, there is a vacancy of 2 cells, and the cell discard state is cancelled, so the data is written into the buffer. Similarly, the C4 cell is also written in the buffer, as shown in FIG.
[0044]
In this manner, after the buffer is once full, cells are not written into the buffer until there is a space for 3 cells. Therefore, after the time required to read 3 cells at the speed W has elapsed, VP / VC = A, Three cells B and C can be written. In the above example, V is assumed to be three times W. However, regardless of the relationship between V and W, in the cell discard state, the input cell is discarded and reading is performed. decrease.
Therefore, if the discard release threshold is set to a value smaller by the number of connections than the discard start threshold, cells corresponding to the number of connections can be written, and the unfairness of discard between connections is eliminated. This is not possible with the conventional method of writing a cell as soon as a buffer is available. In addition, the shaping apparatus can be realized with a very simple circuit by simply setting two threshold values and performing discard control.
[0045]
In addition, by making the discard start threshold value coincide with the buffer size, the buffer can be used as effectively as possible.
[0046]
In the first and second embodiments, the data relay apparatus according to the present invention has been described. However, the data relay method according to the present invention can be realized by a similar processing procedure.
[0047]
Here, the characteristics of the present invention described above are summarized as follows.
According to the cell discard control method of the present invention, in an output buffer type ATM switch, a discard start threshold value and a discard release threshold value are provided for each output buffer, and the cell accumulation amount in the buffer is the discard start threshold value. Newly input cells are discarded, and subsequent input cells are discarded until the amount of stored cells in the buffer decreases below the discard release threshold.
[0048]
The cell discard control method of the present invention is characterized in that the discard start threshold is set to a buffer size, and the discard release threshold is set to a value obtained by subtracting the number of incoming lines from the buffer size.
[0049]
Further, the cell discard control method of the present invention is a shaping device that stores ATM cells in a buffer and reads them at a certain speed, and provides a buffer with a discard start threshold value and a discard release threshold value to store cells in the buffer. A newly input cell is discarded when the amount is the discard start threshold value, and the subsequent input cells are discarded until the accumulated amount of cells in the buffer decreases below the discard release threshold value.
[0050]
The cell discard control method of the present invention is characterized in that the discard start threshold value is set to a buffer size, and the discard release threshold value is set to a value obtained by subtracting the number of input connections from the buffer size.
[0051]
【The invention's effect】
As described above, according to the present invention, fairness of cell discard between incoming lines is guaranteed. That is, there is an effect that unfairness between incoming lines can be prevented without performing incoming line rotation.
In the line rotation, it is necessary to store the priority order by rotation and to write to the buffer in accordance with the priority order that changes every cell time, and the circuit becomes complicated. According to the present invention, two threshold values are used. It has the effect that it can be realized with a simple circuit.
[0052]
In addition, by making the discard start threshold value coincide with the buffer size, the buffer can be used as effectively as possible.
[0053]
Further, according to the present invention, after the buffer becomes full, cells are not written to the buffer until a predetermined number of cells are available, so the number of cells in the buffer is always reduced to the discard release threshold.
Therefore, if the discard release threshold is set to a value smaller by the number of connections than the discard start threshold, cells corresponding to the number of connections can be written, and the unfairness of discard between connections is eliminated. This is not possible with the conventional method of writing a cell as soon as a buffer is available. In the present invention, only two threshold values are set and discard control is performed, which can be realized with a very simple circuit.
[0054]
In addition, by making the discard start threshold value coincide with the buffer size, the buffer can be used as effectively as possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an ATM switch according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing cell discard control processing according to Embodiment 1 of the present invention.
FIG. 3 is a diagram showing an operation according to the first embodiment of the present invention.
FIG. 4 is a diagram showing an operation according to the first embodiment of the present invention.
FIG. 5 is a diagram showing an operation according to the first embodiment of the present invention.
FIG. 6 is a diagram showing an operation according to the first embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of a shaping apparatus according to Embodiment 2 of the present invention.
FIG. 8 shows an operation according to the second embodiment of the present invention.
FIG. 9 shows an operation according to the second embodiment of the present invention.
FIG. 10 shows an operation according to the second embodiment of the present invention.
FIG. 11 is a diagram showing a configuration of a conventional ATM switch.
FIG. 12 is a diagram showing a cell discard control operation of a conventional ATM switch.
FIG. 13 is a diagram showing a cell discard control operation of a conventional ATM switch.
FIG. 14 is a diagram showing a cell discard control operation of a conventional ATM switch.
FIG. 15 is a diagram illustrating an operation of cell discard control of a conventional shaping device.
FIG. 16 is a diagram illustrating an operation of cell discard control in a conventional priority control circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 buffer, 2 cell receiving part, 3 distribution circuit, 4 cell discard part, 5 discard start threshold value setting part, 6 discard cancellation threshold value setting part, 7 accumulation | storage amount measurement part, 10 ATM switch, 20 shaping apparatus.

Claims (10)

Data relay that receives transmission data transmitted from the data transmission device, temporarily accumulates the received transmission data, and discards the received transmission data when the accumulated amount of transmission data exceeds a certain amount A device,
A data receiving unit for receiving transmission data transmitted from the data transmitting device;
A buffer unit for temporarily storing transmission data received by the data receiving unit;
An accumulated amount measuring unit for measuring an accumulated amount of accumulated transmission data accumulated in the buffer unit;
A transmission data discarding unit for discarding transmission data received by the data receiving unit based on the measurement result of the accumulated amount measuring unit;
A discard start threshold value setting unit that sets a discard start threshold value that is an accumulated amount of accumulated transmission data from which the transmission data discard unit starts discarding transmission data received by the data receiving unit;
A discard stop threshold for setting a discard stop threshold, which is an accumulated amount of stored transmission data equal to or less than the discard start threshold, in which the transmission data discarding unit stops discarding transmission data received by the data receiving unit. A value setting unit,
The transmission data discard unit
When the accumulated amount of accumulated transmission data measured by the accumulated amount measuring unit reaches the discard start threshold set by the discard start threshold setting unit, the accumulated amount of the accumulated transmission data becomes the discard After the start threshold value is reached, the transmission data received by the data receiving unit starts to be discarded, and the accumulated amount of accumulated transmission data measured by the accumulated amount measuring unit is set by the discard stop threshold value setting unit A data relay device that stops discarding transmission data received by the data receiving unit when the threshold value is reduced to the discarded threshold value. The data relay device according to claim 1, wherein the discard start threshold value setting unit sets the discard start threshold value based on a predetermined level of the allowable storage amount of the buffer unit. The data receiving unit receives transmission data from at least one data transmission device via at least one communication path,
The data relay device according to claim 1, wherein the discard stop threshold value setting unit sets the discard stop threshold value based on the number of the communication paths. The data receiving unit receives transmission data of the same amount of data from each of at least one or more data transmission devices,
The discard start threshold value setting unit sets the maximum accumulation allowable amount of the buffer unit to the discard start threshold value,
The discard stop threshold value setting unit subtracts a value obtained by subtracting a value obtained by multiplying the data amount of the transmission data from the number of communication paths from the maximum accumulation allowable amount of the buffer unit from the discard stop threshold. 4. The data relay device according to claim 3, wherein the data relay device is set to a value. 5. The data relay device according to claim 1, wherein the data relay device is an output buffer type ATM (Asynchronous transfer mode) switch device. 5. The data relay apparatus according to claim 1, wherein the data relay apparatus is a shaping apparatus that receives an ATM (Asynchronous Transfer Mode) cell. Data relay that receives transmission data transmitted from the data transmission device, temporarily accumulates the received transmission data, and discards the received transmission data when the accumulated amount of transmission data exceeds a certain amount A method,
A data reception step of receiving transmission data transmitted from the data transmission device;
An accumulation step for temporarily accumulating transmission data received in the data reception step;
An accumulation amount measuring step for measuring an accumulation amount of the accumulated transmission data accumulated by the accumulation step;
A transmission data discarding step for discarding the transmission data received by the data receiving step based on the measurement result of the accumulated amount measuring step;
A discard start threshold setting step for setting a discard start threshold that is an accumulation amount of accumulated transmission data in which the transmission data discarding step starts discarding the transmission data received by the data receiving step;
A discard stop threshold for setting a discard stop threshold value, which is an accumulated amount of stored transmission data equal to or less than the discard start threshold value, wherein the transmission data discarding step stops discarding the transmission data received by the data receiving step. A value setting step,
The transmission data discarding step includes:
When the accumulated amount of accumulated transmission data measured by the accumulated amount measuring step reaches the discard start threshold set by the discard start threshold setting step, the accumulated amount of the accumulated transmission data becomes the discard After reaching the start threshold, discard of the transmission data received by the data reception step is started, and the accumulated amount of accumulated transmission data measured by the accumulated amount measuring step is set by the discard stop threshold setting step A data relay method characterized by stopping discarding of transmission data received in the data reception step when the threshold value is reduced to the discarded threshold value. 8. The data relay method according to claim 7, wherein the discard start threshold value setting step sets the discard start threshold value based on a predetermined level among the accumulation allowable amount of the accumulation step. The data receiving step receives transmission data from at least one data transmission device via at least one communication path,
8. The data relay method according to claim 7, wherein the discard stop threshold value setting step sets the discard stop threshold value based on the number of the communication paths. The data reception step receives transmission data of the same amount of data from each of at least one data transmission device,
The discard start threshold setting step sets a maximum accumulation allowable amount of the accumulation step to the discard start threshold,
In the discard stop threshold setting step, a value obtained by subtracting a value obtained by multiplying the data amount of the transmission data by the number of communication channels from the maximum storage allowable amount in the storage step is the discard stop threshold. The data relay method according to claim 9, wherein the data relay method is set to a value.

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