JP2810218B2 - Method and apparatus for evaluating throughput of virtual circuit using time division multiplexed transmission channel - Google Patents

Description

The present invention relates to a method and an apparatus for evaluating the throughput of a virtual circuit using an asynchronous time division multiplex transmission channel.

Asynchronous time division multiplexed transmission channels are transmission channels that carry data messages in a digital data structure called information unit blocks or cells. Each cell includes a header composed of, for example, 8 bits and 4 characters, and a message body composed of a predetermined number of characters, for example, 32 characters. Such cells are continuously transmitted to the transmission channel without interruption. When there are no messages to be transmitted, the transmission channel carries "blank" cells, i.e., cells having the same format as the message cells and containing legible information. An arrangement has been adopted in which the message cell stream maintains a sufficient percentage of blank cells.
That is, such a blank cell performs a function of synchronizing the receiving terminal with the cell format.

For example, two characters in the header of each message cell code an information item used by the receiving terminal to define the retransmission direction of the message body. 2 remaining headers
The characters are the leading 2 regarding the service information and cell destination.
Includes code check and error detection information for characters.
The headers of cells of the same destination, which are irregularly spaced, contain the same information. Therefore, this information can be considered as a kind of virtual circuit that occupies a part of the transmission capacity of the transmission channel. More generally, this virtual circuit occupies a part of the transmission channel and introduces a throughput of the virtual circuit, indicated, for example, by the number of cells per unit time, which is a variable value. The purpose of the present invention is exactly to evaluate the throughput of this virtual circuit.

A transmission channel always supports multiple virtual circuits,
The cells of the virtual circuit are randomly inserted in a so-called asynchronous time division multiplex transmission channel. The throughput is a variable value, and the throughputs of different virtual circuits are different values. The sum of these throughputs is a value that is limited by the maximum throughput of the transmission channel and also varies. Therefore, a space for transmitting a blank cell is maintained.

Also, the number of virtual circuits that can be separately identified depends on the number of bits allocated to this information in the header of the cell. The maximum number of virtual circuits is determined in particular by the number of virtual circuits obtained by dividing the maximum throughput of the transmission channel by the minimum throughput of the data source using virtual circuits. This value is extremely large and reaches, for example, 64K.

However, asynchronous time division multiplexing transmissions are expected to have the widest range of applications, and consequently the bit rates of virtual circuit sources also vary over a very wide range (eg, several kilobits per second to hundreds of megabits per second). Therefore, the actual number of virtual circuits is generally less than the maximum number.

Asynchronous time division multiplexed transmission channels are designed to carry data supplied from sources at a wide variety of varying bit rates. The messages contained in the cells are conveyed to the destination by switching devices and transmission devices arranged along the transmission line to the destination.
Therefore, in order to avoid congestion downstream of the transmission line, it is necessary to check at the transmission channel under consideration that there is no source that introduces a throughput exceeding the total throughput allocated to the circuit due to failure or fraud. . In the presence of such sources, a common correction operation would be to block the cells determined to have exceeded the total throughput allocated to the virtual circuit and not carry them on the transmission channel, or at least mark them as excess cells, Delete from the transmission line when congestion occurs. The present invention relates to a system for evaluating the throughput of a virtual circuit which performs such a test and indicates an excess cell as a result.

Systems of this kind are already known. For example, FR-A-2,616,024 teaches the use of clocks and counters with one threshold per virtual circuit for this purpose. The counter moves forward every cell and moves backward every clock pulse. When the speed of the cell becomes faster than the speed of the clock pulse, the counter reaches the threshold and a signal output is generated.

Such a system cannot be used when the number of virtual circuits is very large and the cell duration is very short (for example, 500 ns). This is because the time required to increment all counters after one clock pulse exceeds the duration of one cell.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for evaluating the throughput of a virtual circuit which meet the above demands. The invention is also very flexible and can be adapted to a variety of use conditions.

SUMMARY OF THE INVENTION In order to evaluate the throughput or bit rate of a virtual circuit carrying cells using an asynchronous time division multiplexed transmission channel, the present invention provides a storage including a data set called a context defining conditions for evaluating the throughput of said virtual circuit. A memory for allocating a location to each virtual circuit is used, and the context of the virtual circuit to which the cell belongs is read every time each cell is received in order to evaluate the throughput of the virtual circuit. A method is provided that includes the use of a clock signal designed to provide a current time associated with a circuit. A feature of the method of the present invention is that when one cell of the virtual circuit arrives, one start time indicator is written to the context of the virtual circuit, and when the next one cell of the same virtual circuit arrives, the context is The start time read from the context is subtracted from the current time given by the clock signal to calculate a time difference, and the time difference is read from the storage location assigned to the virtual circuit. Obtaining a measured value of the throughput of the virtual circuit from the number of time intervals between cells counted between the written cell and the time of the next cell.

A feature of the present invention is that a start time indicator is written in the context of the virtual circuit each time one cell of the virtual circuit arrives, and the context is assigned to the virtual circuit each time the next cell of the same virtual circuit arrives. A time difference is set by subtracting the start time read from the context from the current time read from the stored location and provided by the clock signal, the time difference being defined as the time interval elapsing between the two cells. Constituting a measurement of the instantaneous throughput of the virtual circuit expressed in a predetermined unit, wherein the measurement of the instantaneous throughput is supplied to an evaluation means for determining the necessity of a correction operation, and the current time is used as a start time in the context. It is to be written.

With the above features, it is possible to evaluate the throughput of the virtual circuit from the observed value at the time of arrival of the cell simply by accessing the context at the time of arrival of each cell, and it is possible to process a large number of virtual circuits. is there. In addition, it is possible to measure a throughput in which a correction operation is performed when a threshold value is exceeded during reception of each cell. In other words, virtually immediate operation is possible even if the throughput suddenly exceeds.

According to another feature of the invention, the context includes a count of the number of cells received, the count is incremented for each reception of each cell of the virtual circuit, the incremented count is compared to a particular count, Providing the time difference defined as the time interval elapsed between two discontinuous cells only when the count number of the cells reaches a specific count value as a measurement value of the instantaneous throughput of the virtual circuit, and counting the number of received cells. Is reinitialized.

According to this feature, it is possible to set an evaluation relating to the average time interval between the number of cells defined by the specific count value. This specific count value is also contained in the context and may therefore be a parametric value.

According to another feature of the invention, the context includes a specific duration of a measurement interval and a number of received cells, and for each cell reception, comparing the time difference with the measurement interval duration, Further, when the time difference is smaller than the duration of the measurement interval, the number of the received cells is incremented, and only when the time difference is equal to or more than the duration of the measurement interval, the increment number of the received cells is given. It is provided as a measure of the average throughput of the virtual circuit, defined as the number of cells received in the time interval, and at the same time the number of received cells and the start time of the measurement interval are re-initialized.

With such a feature, it is possible to provide an instantaneous throughput measurement that includes the time interval between consecutive or non-consecutive cells from a measurement on the number of cells received at a given time interval. Such measurements can be performed economically and obtained with the desired accuracy by selecting a time interval of appropriate duration, such as the number of cells to be received at this time interval during normal traffic.

According to another feature of the present invention, a plurality of throughput measurements sequentially set for a given virtual circuit are accumulated and the accumulated values are presented as accumulated throughput measurements.

According to another feature of the invention, the context comprises at least one data item constituting a throughput counter, wherein a context between a predetermined value corresponding to the allowed throughput expressed in the predetermined unit and one of the measured values of the throughput. , And then compares the arrival position of the throughput counter with respect to a particular end position, and generates a signal indicating the need for a corrective operation when the end position is reached or passed.

According to another feature of the invention, the context includes at least one throughput threshold, and comparing one of said throughput measurements to said threshold to determine at which interval between said thresholds said measurement is present Correcting the count value as a function of the determined interval,
It is determined that the count value has reached the end position in the first direction, and a signal indicating the necessity of a correction operation is supplied.

According to another aspect of the invention, the method comprises a plurality of throughput thresholds and a count value, wherein one of the throughput measurements is compared to the threshold to determine at which interval between the thresholds the measurement is present. Then, the count value is corrected according to the determined interval, and further, it is determined that the count value has reached the end position in the first direction, and a signal indicating the necessity of a correction operation is supplied.

According to another feature of the invention, including the context allowed maximum throughput indication, comparing the maximum throughput indication with the observed throughput for each cell arrival,
If the observed throughput is greater than or equal to the maximum allowed throughput, the signal indicating the need for a corrective action is provided.

According to another feature of the invention, when said throughput counter or said count value arrives at a terminal position, a marginal throughput value dependent on a corresponding throughput threshold serving the same function as the allowed maximum throughput indication is used in said context. .

The present invention also provides a memory for allocating a storage location including a data set called a context that defines an evaluation condition of a virtual circuit throughput to each virtual circuit, and a memory for each cell reception for evaluating the throughput of the virtual circuit. An apparatus is provided that includes means for reading the context of a virtual circuit to which it belongs, and a clock signal source designed to supply a current time corresponding to the virtual circuit expressed in a predetermined unit. The device of the present invention is characterized in that means for writing a start time indication in the context of the virtual circuit when one cell of the virtual circuit arrives, and storage allocated to the virtual circuit when the next one cell of the same virtual circuit arrives. Means for reading the context from a location, and means for subtracting the start time read by the context from the current time supplied by the clock, wherein the time difference set by the subtraction and the start time are written. A measure of the throughput of the virtual circuit is obtained from the number of time intervals between cells counted between the time of the next cell and the time of the next cell.

Further, the time difference can be considered to be an instantaneous throughput measurement of the virtual circuit defined as the time interval elapsing between the two cells, and the apparatus of the present invention uses the instantaneous throughput to determine the need for corrective action. Means for providing a throughput measurement to an evaluation means, and means for determining to write in the context the current time as a start time.

According to another feature of the invention, the context includes a count of received cells, and means for incrementing the count each time a cell is received by the virtual circuit, and wherein the incremented count is a specific count value supplied by the context. Means for operating only when the received cell count reaches a specific count value, and using the time difference defined as the time interval elapsed between two discontinuous cells as an instantaneous throughput measurement value of the virtual circuit. Means for providing and reinitializing the received cell count.

According to another feature of the invention, the context comprises a specific duration of the measurement interval and the number of received cells, and means for comparing the time difference and the duration of the measurement interval for each cell reception; and Incrementing the number of received cells when is less than the measurement interval duration,
Providing the incremental number of received cells as a measure of the average throughput of the virtual circuit defined as the number of cells received at a given time interval only when the time difference is greater than or equal to the measurement interval duration, and at the same time Means for re-initializing the number.

According to another feature of the invention, means for accumulating a plurality of said throughput measurements set sequentially for a given virtual circuit and providing the whole as an accumulated throughput measurement is provided.

According to another feature of the invention, the context includes at least one throughput counter, and corrects the content of said counter by adding the difference between a predetermined value corresponding to the allowed throughput and one of said throughput measurements. Means for comparing the arrival position of the throughput counter with the specific end position, and generating a signal indicating the necessity of a correction operation when the former is greater than or equal to the latter.

According to another feature of the invention, the context comprises at least one throughput threshold, means for comparing one of said throughput measurements to said threshold, above said threshold, activating a throughput counter in a first direction, If the threshold value is less than the threshold value, means for activating in the other direction and means for determining that the throughput counter activated as described above has reached the end position in the first direction and supplying a signal indicating the necessity of a correction operation are provided.

According to another feature of the invention, the context has a plurality of throughput thresholds and at least one count value, and a throughput measurement for determining at which interval the throughput measurement is between the thresholds. Means for comparing one of the values with the threshold value, correcting the count value by an amount as a function of the interval determined as described above, and determining and correcting that the count value has reached the end position in the first direction. Means for generating a signal indicating the need for operation.

According to another feature of the invention, the context includes an allowed maximum throughput indication, and compares the observed throughput with the maximum throughput indication for each cell arrival, and corrects if the observed throughput is greater than or equal to the allowed maximum throughput. Means for providing a signal indicating the need for operation.

According to another feature of the invention, each time the throughput counter or the count value reaches a terminal position, a limit throughput value that depends on a corresponding throughput threshold that performs the same function as the permitted maximum throughput indication is written into the context. Including means.

According to another feature of the invention, the clock signal source provides a current time corresponding to the virtual circuit via a clock selection module controlled by a clock signal selection indication provided by the context of the virtual circuit. As a result, the output group of the master clock is selected, and the least significant bit output characterizes a predetermined unit used for measuring the duration involved in the evaluation of the throughput.
The predetermined unit is selected so as to obtain a desired accuracy in the evaluation value.

As a result, the time display for the virtual circuit can be adapted to the throughput of the virtual circuit itself, and the desired accuracy can be obtained without increasing the size of these displays, ie, the number of bits.

The above and other objects and features of the invention will be more fully understood from the following description based on non-limiting embodiments illustrated in the accompanying drawings.

First, please refer to FIG. 1 showing an overall schematic diagram of an embodiment of the present invention. 1 is inserted between the cell input ENC and the cell output STC. The system is inserted into an asynchronous time division multiplex transmission channel. Specifically, the bit rate of the transmission channel received at the input ENC is, for example, 600 Mbit / sec. This data stream passes through a cell transmit / receive block BREC illustrated as a shift register. As long as the throughput of the virtual circuit supported by the link, i.e. the bit rate, is acceptable, all cells received at the input ENC will be output with a transmission time of e.g. one cell, e.g. with a delay equal to about 0.5 microseconds Sent to STC as is.

According to the example mentioned at the beginning of the text, one cell has a header of four characters, two 16 bits of the header indicating the virtual circuit number. The cell also contains a 32-character message body.

When the header of one cell enters the block BREC, this header ET is sent to the processing context access block BACT. The virtual circuit number CV in the block BACT is used as an address for reading the processing context CT of the virtual circuit to which the received cell belongs from the processing context memory MCT. This processing context CT consists of a set of digital information, some of which is semi-permanent information fixed for the duration of communication using virtual circuits,
The rest is variable information that can change every time each cell of the virtual circuit is received.

The access block BACT sends the read processing context CTL to the processing block BT. The block further receives information about the input order from the counter block BC.
The processing block BT creates an updated processing context CTX based on these two pieces of information, and generates the same address CV
Is returned to the access block BACT so that the received cell is not within the allowable range, and the signal OSC is generated.

The updated context CTX contains variable information, which is changed as necessary as a function of the one-cell reception, ie as a function of the arrival time of the cell indicated by the counter block BC, according to the processing program of the block BT. obtain.

The signal OSC is transmitted to the block BREC, which in the first embodiment replaces the received cells in the block BREC with blank cells. In a second embodiment, the signal OSC marks an indicator provided in the header of the cell. With this mark, in the case of excess throughput, when a cell later enters the switching means, the switching means does not transmit the cell. The signal OSC can be used for other purposes by using the output SOSC of the signal OSC.

It is preferable that the length of time required for the blocks BACT and BT to execute the above operation be equal to the transmission time of one cell. These blocks can then restart a new operating cycle immediately after receiving the next cell. However, as is known in the art, read-processing of a context for a given received cell so that each of the access block BACT and the processing block BT can fully use the time of one cell for processing operations on the cell. The operation of the two blocks may be managed such that the rewrite operation overlaps the same operation on the immediately following cell.

The context data CT is first written into the memory MCT by a control processor (not shown) connected to the access block BACT by the link CMP. The processor supplies the address CV of the virtual circuit and the context information CT for each write operation. The block BACT may include, for example, blank cell identification means, and may be configured to perform a writing process of a new context within the reception time of each blank cell.

Block BACT finally contains an activity monitor, and the processor reads its activity report by link CMP.

The blocks BREC, BACT, BT, and BC are shown inside the frame surrounded by a dotted line because, as described later, these blocks are collectively formed in the form of an application specific integrated circuit (ASIC). is there.

In the following description, the transmission / reception block BREC will not be described in detail, but this block is essentially a shift register. The counter block BC will not be described in detail, but this block is a simple block which is incremented by one step every period of the internal clock and circulates through all positions.
Hex counter. The number of stages of this counter will be described later. Although the access block BACT is not described in detail, the function of this block is clearly defined, and a method of manufacturing the block and a technique of combining the block with the memory MCT will be apparent to those skilled in the art.
Only the processing block BT will be described in detail below.

This processing block BT is shown schematically in FIG. The block contains six types of processing modules. That is, at least one clock selection module MSH,
At least one throughput measurement module MMD;
It includes at least one result quantization module MQR, at least one result reduction module MRR, at least one count management module MGC, and at least one decision module MSC.

The clock selection module MSH is shown in FIG. FIG. 3 also shows a block BC composed of a series of binary stages controlled by a clock HG supplying a pulse h.
Shows the counter CBC. Outputs S0 to S (d +) of counter CBC
m + e) is coupled to the clock selection module.
The module further receives from the context CT supplied by the access block BACT a clock selection indication selh consisting of a binary indication that can take on the value of e + 1 sequentially.
This indication is given to m multiplexers MU1 to MUm,
The result is that all multiplexers have the same orientation. Each of these multiplexers is connected to one output group having e + 1 outputs of the counter CBC, and the m output groups themselves shift one or more outputs from the multiplexer MU1 to the multiplexer MUm. Accordingly, the multiplexer MU1 is connected to the outputs Sd to S (d + e) of the counter, and the multiplexer MUm is connected to the outputs S (d + m) to Db.
= S (d + m + e). Finally, the outputs M1 to Mm of the m multiplexers provide the current time hc in binary form with valid bits u to u + m. The valid bit u depends on the display value selh. Thus, each of the virtual circuits has a clock signal defined by its processing context indication selh and suitable for its throughput or bit rate.

However, it should be noted that a plurality of clock selection blocks similar to the clock selection blocks as described above can be provided together. From the following description, it will be appreciated that all of the throughput measurement modules utilize the current time provided by the clock selection module. When all the measurement modules can use the same current time, the clock selection module as shown in FIG.
One. In some cases it is necessary to supply different current times to the various measuring modules, in which case the same number of clock selection modules as the measuring modules are required.

The processing block BT then includes one or more throughput measurement modules MMD1 to MMD3.

First, the module MMD1 will be described with reference to FIG. This module receives the following information from the context CT supplied by block BACT:

-The duration T of the measurement time interval expressed as a period u;-the value of the period u;-the start time ha1 of the measurement time interval T set later based on the current time hc;-the time interval T of the current time. Number of received cells n1, number of bits B per cell.

The module MMD1 also receives the current time hc supplied from the module MSH.

The module MMD1 calculates the difference hc-ha1. This difference is T
If it is less than the value, the value n1x = n1 + 1 is given to the block BACT and replaced with the value n1 of the context CT. Conversely, when the difference is greater than or equal to T, the value Dm1 =
Give a validation signal Val1 with n1. At this time,
A value n1x = 1 and a value ha1x = hc are given to the block BACT, and these values are written in place of the values n1 and ha1 of the context CT. Therefore, the start time written in the processing context CT is the reception time of the preceding cell whose value n1 is equal to 1.

Thus, the value of the throughput Dm1 set at the end of each measurement interval with a duration at least equal to T can be represented by the formula n1 * B / (T * u), which expresses the period u in seconds. Indicates the number of received bits per second when performing However, as noted above, at Dm1 = n1, the measurement does not include the factor B / (T * u). Therefore, module MMD1 does not need to receive the values u and B from the processing context, these values being used only when utilizing the result. It will be described later that these factors which are not present in the measurement result are used in the block utilizing the measurement result. Further, the value B may be a constant of the transmission system,
It should also be understood that the value T may be a constant of the evaluation system. In this case, these values are not supplied by the context CT but are included as constant values in the modules of the processing block BT.

Finally, it is necessary to mention the measurement of the measurement time interval T. This measurement is not made rigorously but is accurate enough. Actually, as described above, this period is fixed to 1 after receiving a predetermined number of cells, starting from the arrival time of one cell. Next, the cells are counted until the difference hc-ha1 receives a cell whose measurement time interval has been exceeded. Since the measurement interval has been completed, the last cell is not included in the throughput indication, but is included in the count of the next measurement interval. Therefore, all cells are counted. If there is a gap between the measurement time intervals, the accuracy decreases. The error is equal to or less than one-seventh of the cell count for each measurement time interval. When the number of cells is sufficiently large at the planned average throughput, the error can be ignored.

The throughput measurement obtained by module MMD1 as described above is given by the number of cells received in the measurement time interval up to the arrival of the cell under consideration.

The module MMD2 in FIG. 5 is a clock selection module
In addition to the time hc obtained from the MSH, the value B2 defined above and the value ha2 read at the time of reception of the preceding cell to become the current time.
And receive. These two values are obtained from the processing context CT given by the block BACT.

Therefore, the module MMD2 calculates the difference hc-ha for each cell arrival.
2 to provide a validation signal Val2 with the value Dm2 = hc-ha2 for the next module MQR, MRR or MGC. The module MMD2 also supplies to the block BACT the value ha2x = hc which is written into the context CT, replacing the value ha2.

Strictly, the throughput set as described above for each reception of each cell must be a value calculated by the formula B / (hc-ha2) * u, but the measurement result Dm3 includes the factors B and u. Not. These factors will be used in the next module as described below. The value B may be a transmission system constant as described above.

In the case of this module MMD2, the measurement of the throughput is given directly by the time interval elapsed between the cell immediately after arrival and the preceding cell of the virtual circuit under consideration.

The module MMD3 in FIG.
In addition to the current time hc obtained from H, B defined earlier,
The value ha3 written as the current time at the time of receiving the first cell of the group of N cells, the count number n3 of the received cells of the group of N cells, and the count number of the cells of the group are The value N to be reached is received. These various values are obtained from the processing context CT.

The module MMD3 first calculates the count number n3 as n3x = n3 + 1
, And then compare the count number n3x to the value N. n3x <
When N, module MMD3 blocks count number n3x in block B
Give to ACT and update the processing context CT (value ha3 is unchanged). When n3x = N, the module MMD3 calculates the difference hc-ha3 and supplies the validation signal Val3 with the value Dm3 = hc-ha3 to subsequent modules of the MRR, MQR or MGC type. Further, the value ha3x = hc and the value n3x = 0 are supplied to the block BACT, and these values are replaced with the values ha3 and n3 and written into the context CT.

The exact value of the throughput set as described above for each reception of each cell is expressed by B * N / (hc-ha3) * u, but the factors B, N and u are included in the measurement result Dm3. Absent. These factors are used in subsequent modules. Further, the value B may be a constant of the transmission system as described above.
The value N may be a constant of the evaluation system.

The throughput measurement provided by module MMD3 is indicated as the duration of the time interval required to receive N cells. This measurement may also be considered to be the average time interval between consecutive cells evaluated for N cells multiplied by N constants as well.

The processing block BT then comprises at least one result quantization module MQR. This module may have the shape of the module MQR1 shown in FIG. The module MQR1
Is the measured value Dm of the measured throughput, i.e. the measurement results Dm1, Dm2, obtained from one of the preceding modules MMD1 to MMD3.
One of Dm3 and the throughput threshold Di obtained from the processing context CT are received. The module MQR1 compares them with each other and generates a result signal R0i when the measured throughput value is less than the threshold value, and generates a result signal R1i when the measured throughput value is equal to or greater than the threshold value. These signals are processed in the next module MRR or provided directly to one of the count management modules MGC.

In a modification, the result quantization module MQR may have the shape of the module MQR2 shown in FIG. Module MQR2,
The value Da is received from the context CT in addition to the values Di and Dm.
The values Di and Da are combined in the module MQR to form the threshold scale D
i, Di + Da, Di + 2 * Da ..., Di + k * Da are given. The module compares the value Dm to this set of thresholds and generates a result signal Ri0 only when it is less than the minimum threshold, and generates a signal R1i when it is equal to or greater than the threshold Di and less than the subsequent threshold, and so on. Result signal R (k +
1) Generate i. These signals are processed in the result reduction module MRR or the count management module MGC
Given directly to

Module MQR2 may be further modified so that the various values of the threshold display scale are provided directly by the context.

The result reduction module MRR is an optional element. Module MRR is after the throughput measurement module MMD1 to MMD3,
Or it may be deployed after the result quantization module MQR.
An embodiment of such a module is shown in FIG. The function of the module is to accumulate some measurements, quantized or unquantized. This module receives the following values from the processing context CT.

The number C of measurement results to be accumulated; the number c of accumulated results; and the accumulated value mc of the obtained c measurement results.

The module further receives a measurement result Rm, such as Dm1, Dm2 or Dm3, from a previous throughput measurement module, or a result signal Ri0, Ri1,..., Rik + 1 from a previous result quantization module. The module finally sends the signals Va1, V
Receives a validation signal Val such as a2 or Va3.

Based on the above signal, the reduction module MRR is calculated as
Set c + 1 and compare this number to the number C. At the same time, the module MRR calculates the sum mcx = mc + Rm. When cx <C, since the number of results to be accumulated has not yet been reached, the module MRR determines the values cx and m to update the processing context CT.
Supply cx. When cx = C, the module MRR becomes cx =
0 and mcx = 0 are supplied to the context, and the subsequent block, for example, the result quantization block MQR or the count management block MGC, supplies the validation signal Vlr and the measurement result signal RR.
m = mc. These two pieces of information are transmitted to subsequent blocks by the throughput measurement modules MMD1, MMD2, and MM.
It has the same meaning as the information Val and Dm of D3.

Next, two modified examples of the count management module MGC will be described. The MGC1 shown in FIG. 10 is used, for example, when measuring the throughput by the throughput measurement module MMD1 or the result reduction module MRR used with such a measurement module. The deformation module MGC1,
Upon receipt of one cell, if there is a corresponding validation signal Valv (obtained from the validation signal Val1 or Vlr as described below), the throughput value Vm (ie Dm1 or RRm) supplied by the module is directly used I do. Further, the module MGC1 receives, from the block BACT, a throughput threshold value Ds, a throughput minimum value Do, a throughput counter position CPi, a maximum count threshold value CMAX, and a minimum count threshold value CMIN. These are the information provided by the context CT, all in the same unit,
Here, it is expressed by the number of cells. The minimum count threshold may be zero. In this case, this value is not supplied by the context.

In this first modification, the module MGC1 compares the value Vm with the throughput value Do. When Vm <Do, no operation is performed, and various information of the context does not change. When Vm is equal to or greater than Do, the count number CPi is increased by Vm and decreased by Ds, and a count result CPx is obtained. Compare this value to CMAX. When CPx> CMAX, the result is modified to CPx = CMAX and written to the context CT. This means that the throughput is above the minimum value, ie outside the “silence” period, and the throughput evaluated by the counter is always the throughput threshold.
When it is maintained below Ds, it means that the counter CPi reaches the value CMAX and is maintained at this value. For this reason, a margin is provided when a state in which the threshold value is exceeded occurs later. At the same time, the result CPx is compared to the value CMIN. CPx <CM
When IN, the result is modified to CPx = CMIN. Here the instruction OSS
CI is sent. This instruction gives the signal OSC (see the description relating to FIG. 1) together with other instructions of the same module. This indicates that the throughput has exhausted the margin and has exceeded the threshold value Ds. This instruction indicates the cell in question as an excess cell and causes a corrective action to be taken. Instruction OSC1
Is further written to the context. This prevents an unexpected overrun of the throughput from being carried over in the next measurement period. Finally, when CMAX <CPx <CMIN, the value CPx is set to the value CPi in the context CT without any other operation.
become.

From the above variant of the count management module, the measurement value Vm is supplied by either the throughput measurement module MMD2 or MMD3 or by the result reduction module MRR used in conjunction with one of the modules. It will be clear that such variants can be made. The information provided to the count management module is comprised of units of duration defined by the selected clock signal.

In this variant of the first variant, the module MGC1
The value Vm is compared with the throughput value Do. When Vm> Do, no operation is performed and the context information is maintained unchanged. When Vm <Do, the count number CPi decreases by Vm and increases by Ds. The count result CPx given as a result is compared with CMIN. When CPx <CMIN, the result is
Correct CPx = CMIN and write this to context CT. This is when the throughput is above the minimum, i.e. outside the "silence" period and when the interval between cells is below the minimum, and when the throughput evaluated by this counter is always below the throughput threshold Ds. Means that the counter CPi reaches the value CMIN and is maintained at this value. For this reason, even when the threshold value is exceeded later, such a margin is provided. Similarly, the result CPx is compared to the value CMAX. When CPx> CMAX,
Correct the result to CPx = CMAX. Here, the instruction OSC1 (see above) is sent. This instruction is also written to the context CT. Thus, exceeding the throughput threshold Ds occurs after the available margin has been exhausted. The cell that caused this processing must be marked as an excess cell. Finally, when CMAX <CPx <CMIN, the value of CPx becomes the value CPi of the context CT without any other operation.

Next, a third variation of the count management module MGC1 will be briefly described. This module uses the MQ shown in FIG.
Processes information provided from the R1 type result quantization module. This variant almost corresponds to the first two variants, the only difference being that the threshold Di supplied to module MQR1 is
The throughput counter moves forward or backward by one step, depending on whether an overrun has occurred.

FIG. 11 shows a second modification MGC2 of the count management module. This variant is used when the measurements are provided by a result quantization module, such as the module MQR2 of FIG. For each cell, the module MQR2 characterizes the threshold excess for different thresholds. That is, module MQR2 provides a Rij indication (i = threshold scale; j = 0..., K + 1) indicating that the measured value is at the interval between threshold j and the next threshold j + 1. The value Rij corresponding to one of these thresholds is provided to the count management module MGC2 together with the validation signal vlaw. This validation signal is supplied from a measurement module that provides a quantized measurement result, and as described later, a module M is set at the same time as a count value SPi, a maximum count threshold SMAX, a minimum count threshold SMIN, and a count scale Kij that are set each time a preceding cell is received.
Given to GC2.

The count scale Kij is a group of count values, and the value R
One for each of ij.

One of the values of the count scale Kij is excited according to the information Rij, and this value (positive or negative) is added to the count value SPi. Next, the corrected value SPx is compared to a maximum threshold SMAX. When SPx> SMAX, an instruction OSC2 similar to the instruction OSC1 (see above) is generated. At the same time, the corrected value SPx is compared to a minimum threshold SMIN. When SPx <SMIN, the value SPx is SPx = S
Limited to MIN. No other operations are performed.

The same indication Ri supplied by the result quantization module
j is transmitted to a plurality of count management modules MGC2 having different count scales. As a result, the throughput of the virtual circuit can be evaluated based on different criteria.

The count scale Kij may be a constant of the evaluation system.
In this case, the count scale is not supplied by the context but has been written to module MGC2.
According to a variant, a plurality of separate count scales are written in module MGC2. The information Kij designates one of these scales, and causes the module MGC2 to select and execute this scale.

Regardless of which count management module is used, the use of an instruction OSCi, such as OSC1 or CSC2, also has the advantage of partially inhibiting the updating of the processing context CT. In the case of the MMD2 type module, replacement of the start time ha2 with the current time hax is prevented. As a result, in this module, it is assumed that the cell on which the correction operation was performed did not exist. In addition, it can be configured that the update of the counter (s) of the count management module (s) is not performed.
Thus, all excess cells are eliminated, and the virtual circuit is maintained at an acceptable throughput. More generally, no update of the processing context CT is introduced. In this case, the cell that caused the correction operation is considered not received by the evaluator.

Next, the immediate correction module MSC will be described with reference to FIG. This module complements module MMD1 and the modules that follow it to handle over-throughput conditions. This module receives a value n1x of the number of cells received in the current measurement interval from the module MMD1 at each cell arrival. At the end of each measurement interval, the validation signal val1 is sent from the same module MMD1.
To receive. The module MSC also receives the maximum threshold Dsm and the plurality of intermediate thresholds Dsi from the context CT, and receives a signal corresponding to the correction operation command OSCi from the count management module coupled to the throughput measurement module MMD1. This instruction has been previously written in the context CT in the above-described procedure.

At each cell arrival, the throughput measurement value indicated by the number of cells n1x received at the measurement time interval is compared with the maximum threshold Dsm. When n1x> Dsm, the instruction OSC3 is transmitted. This generates a start command OSC for the correction operation on the arriving cell. Thus, in one measurement interval, when the maximum number of cells has been received and successfully processed, the subsequent cells are considered as excess cells. In this way, a limited number of mutually close cells can arrive with high instantaneous throughput. These cells are stored in modules MMD2 and / or MMDR3
However, if this high throughput continues, cells that exceed a maximum threshold defined by the duration of the relatively long measurement time interval are prevented from passing. When the signal Val1 exists, such a processing procedure is not applied to the reception of the last cell of the measurement time interval.

In the above case, the updating of the context is prohibited by the rejection of the receiving cell, so that all cells subsequently received by the end of the measurement period (the first received after the end of the measurement period) It is also possible to design a procedure that is similarly rejected (except for cells).

Furthermore, when the module MSC receives from the context the instruction OSC1 generated by one of the count management modules that processes the measurement results given from the module MMD1, it selects the value of the corresponding intermediate threshold Dsi given by the context CT. . If the threshold is exceeded, the cell number n1x is also compared to this threshold to generate the instruction OSC3. This process occurs especially when the number of received cells finally exceeds a specified threshold after the margin has been exhausted at the end of the measurement interval. The above-described processing procedure for the maximum threshold reduces the excess of the threshold. The purpose of using an intermediate threshold is
The goal is to keep the occurrence of new threshold crossings at a low level. This level is a level that causes the writing of the instruction OSCi.

Although not described here, if the corresponding excess condition does not reappear, an instruction from the context at the end of the next measurement period
A processing procedure for deleting OSCi is also possible.

According to the present invention, a module similar to the module MSC in FIG. 12 may be provided in combination with the module MMD2 or MMD3. The details are easily deduced from the above description and need not be described.

Next, the overall configuration of the processing block BT will be described with reference to FIG. FIG. 13 shows the relationship between FIGS. 1 and 2 for a given virtual circuit CV.
Block BT module MMD1, MMD2, MMD3, MRR, M in the figure
One for each of QR1, MQR2 and MGC2 and two modules MGC1 and 1
An application example using one module MSC is shown.

At each arrival of each virtual circuit cell CV, the module MMD2 sets the validation signal Val2 and the throughput threshold shown in FIG.
Provide a throughput measurement md2 including Dm2. This value is the duration that separates the arriving cell from the preceding cell of the same virtual circuit. This value is input to the result quantization module MQR2. In the latter module, this value is compared to a threshold given by the context, taking into account the setting conditions of the throughput measurement, in particular the clock period u in which the measurement was expressed. The module MQR2 supplies the output signal ndi to the count management module MGC2. The signals are the result signals Ri0 ..., Ri (k + 1) of FIG. 8 which define the throughput level.
including. The count value of the module changes according to a count scale for each measured throughput level,
The count range of the counter defines the threshold excess tolerance. The persistence of exceeding the threshold generates the rejection command OSC2.

At the same time, the module MMD3 counts the arrival of one cell, and when the count reaches the count specified by the context, sends the measured throughput value md3 to the MGC1-type count management module similar to that shown in FIG. Optionally, a result quantization module such as module MQR1 may be provided before MGC1. This throughput measurement value includes the validation signal Val3 and the throughput value Dm3 in FIG. Value D
m3 is the duration of the time interval separating the arriving cell from the Nth previous cell of the virtual circuit. The value of this throughput is added to the content of the throughput counter managed by the module MGC1, and a value corresponding to the permitted throughput is subtracted from this value. This latter value is also given from the context and takes into account the measurement conditions of the throughput, in particular the duration of the clock period over which the measurement was obtained. In fact, the counter adds a value corresponding to the difference between the allowed throughput and the measured throughput, in other words, the deviation from the specified throughput. This deviation relates to the average time interval evaluated over the group of N cells. Such deviations thus cover a much longer period than the one estimated on the basis of the measurement module MMD2, concealing the throughput spikes appearing in two or three cells very close to each other. Finally, the persistence of the throughput overrun generates the command OSC1 and thus the signal OSC1 as described above.
C is output.

At the same time, module MMD1 counts the arrival of one cell within the measurement time interval. When the measurement time interval ends, the number of cells received in this measurement interval is transmitted as the measurement result dm1. This measurement result dm1 includes the validation signal Val1 and the throughput value Dm1 of FIG. A plurality of such measurement results are accumulated by the module MRR. When the accumulation period ends, the module MRR sends out the measurement result rm including the validation signal Vlr and the measurement result value RRm in FIG. 9 to the MGC1 type count management module. The operation of this module has already been described. Again, a value that is subtracted in consideration of the throughput measurement conditions is defined. As a result, persistence of excess throughput will cause rejection command OSC1. The combination of the measurement time interval defined in the module MMD1 and the accumulation module MRR makes it possible to evaluate the throughput covering a relatively long period and thus to obtain a high accuracy. Using one measurement module MMD1 and a plurality of different accumulation modules MRR, a plurality of different measurement results for different accumulation periods are obtained.

Further, the module MSC receives the number of cells n1x received in the measurement time interval and compares the number of cells n1x with the threshold value as described above,
If the throughput is excessive, the rejection command OSC3 is sent. The module also receives rejection commands OSC2 and OSC1 from the modules MGC2 and MGC1 to set a throughput limit used to reject cells of the virtual circuit if the virtual circuit continues to exceed its throughput.

Finally, an example of the context CT corresponding to the application example of FIG. 13 will be described with reference to FIG.

FIG. 14 shows storage locations each subdivided into rectangular spaces. The number in parentheses at the lower right corner of the space indicates the number of bits. Numerical values and other indications are the same as those in the modules in FIGS. 3 to 12.

The clock selection display selh consists of 4 bits. The display may select one of the 16 clock signals. When the current time of the clock contains 17 bits, the counter CBC will be 3
Including up to 2 bits.

The number of bits of the current time provided by the clock and the start time indication written into the context is determined by the problem raised by the temporarily inactive virtual circuit. When the virtual circuit clock executes one complete cycle without receiving any cells, a rejection decision must not be made even though the throughput is actually very low.
To solve this, for example, the connection source is required to have a minimum throughput, and if there is no connection source, the connection is cut off. This results in artificial throughput. This throughput decreases as the clock cycle of the virtual circuit increases, in other words, as the number of bits at the current time increases.

Next, there are a 17-bit start time ha1 required for the module MMD1, a received cell number n1 (11 bits), and a clock period number T (11 bits) that defines the duration T of the measurement time interval.

When the average rated throughput of the virtual circuit under consideration is 2 Mbit / s, the least significant bit of the virtual circuit related clock signal selected by the indication selh has a period of 8 μs. In contrast, for a cell of about 300 bits, the average interval between cells is 150 μs. Measurement time interval of at least 15,000μ covering an average of 100 cells received
Must be seconds, ie about 2000 clock periods. Therefore, an 11-bit value is required to define the display T.
On the other hand, the number of bits required to count the number of cells received at the measurement time interval must correspond from the average throughput, which can be represented by an 8-bit number, to the maximum number of cells allowed for that time. Therefore, the number n1 was given 11 bits corresponding to a maximum possible throughput of almost 20 times the average throughput. As a result, the thresholds Dsm and Dsa required for the decision module MSC are the same number of bits (1
1).

Display ha2 and ha3 required for modules MMD2 and MMD3 are 17
Bits and based on the same clock signal. The measurement of the time interval between two consecutive cells is up to about 5%. This lack of accuracy is acceptable because the purpose of the measurement is to prevent the most pronounced shortest throughput spikes. The measurements obtained by module MMD3 are clearly more accurate. In response to the request of the module MMD3, the context further provides a value of the number of received cells n3 (6 bits) and a value of the number of cells to be received N (also 6 bits). Therefore, it is possible to measure the average time interval of 1 to 63 cells. Similar values c and C required for the result reduction module MRR are also 6 bits each, giving the same possibility. Therefore, the cumulative value mc of the module MRR is 11 + 6 = 17 bits.

The thresholds Di and threshold increments Da required for the result quantization modules MQR1 and MQR2 are 17 bits and 6 bits, respectively. The time difference hc-ha3 or hc-ha2 may have 17 bits. Therefore, it is compared to a 17-bit threshold that separates a 6-bit number.

The threshold value Ds required for the module MGC1 has 17 bits.
The reason is that the cumulative value provided by the module MRR contains the same number of bits. Here, the threshold value Do is assumed to be zero. The counter CPi controlled by this module has 20 bits. The value CMAX is also 20 bits. The value CMIN may be zero or a constant and is therefore not present in the context.

Also, the count value SPi (four values of 6 bits each)
And the associated threshold SMAX (four thresholds of 6 bits each). The threshold SMIN is also assumed to be zero or a constant. Finally, the context shown is also the same as the 11-bit maximum threshold Dsm required for the immediate rejection module MSC of FIG.
And a bit application threshold Dsa.

A similar virtual circuit with an average rated throughput of 4 Mbits / sec would be treated exactly the same, except for the different clock signals inherent to this virtual circuit. A virtual circuit having an average throughput of 2 to 4 Mbit / sec is processed by a clock signal of the virtual circuit of 4 Mbit / sec. At this time, a parameter for determining the evaluation of the throughput, that is, a period T (shortened), The threshold value Di (increased) of the modules MQR1 and MQR2 or the value Ds (decreased from FIG. 13) of the module MGC1 is appropriately adjusted.

In addition, virtual circuits having the same average rated throughput can tolerate more or less noticeable throughput spikes. Different thresholds Di and Da may be used for modules MQR1 and MQR2. The organization of the modules may be changed as shown in the description of these modules.

The procedure has been outlined above. Values not described but required can be added in a similar manner. Also, values that are considered constants or values selected from a small group of constants that can reduce the size of the context can be used. Encoding methods that can save a considerable amount of data to be stored in memory with only some increase in circuit complexity are well known to those skilled in the art.

There is no technical problem in putting the throughput evaluation device of the present invention into practical use, and the various elements described above need only perform simple logical operations and arithmetic operations. First
As shown, the assembly of blocks BREC, BACT, BT and BC can be manufactured in the form of an ASIC device, ie an integrated circuit. State-of-the-art memory MCTs with built-in context
Will be independent elements. Since the processing block BT has a modular structure, it can be easily adapted to various desired applications. The application example of FIG. 13 is just one embodiment, and other knitting is possible. However, all of these separate organizations can be accessed by a sufficient number of modules of various types, for example via link CMP, and can implement the various organizations of the various modules shown in FIG. 13 (registers and registers). And knitting switches) can be obtained from the same integrated circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram of a processing block BT of the system of FIG.
FIG. 4 is an explanatory view of one embodiment of the clock selection module MSH of FIG. 2, FIG. 4 is an explanatory view of a first embodiment of the throughput measurement module MMD of FIG. 2, and FIG. 5 is a throughput measurement of FIG. FIG. 6 is an explanatory view of a second embodiment of the module MMD. FIG. 6 is a third view of the throughput measurement module MMD of FIG.
FIG. 7 is an explanatory view of an embodiment, FIG. 7 is an explanatory view of a first embodiment of the result quantization module MQR of FIG. 2, FIG. 8 is an explanatory view of a second embodiment of the result quantization module MQR of FIG. FIG. 9 is an explanatory diagram of an embodiment of the result reduction module MRR of FIG.
FIG. 11 is an explanatory view of a first embodiment of the count management module MGC of FIG. 2, and FIG. 11 is a count management module MG of FIG.
FIG. 12 is an explanatory diagram of a second embodiment of C, FIG. 12 is an explanatory diagram of an embodiment of the judgment module MSC of FIG. 2, and FIG. 13 is a function of various modules of a specific virtual circuit processing block BT in a use example of the present invention. FIG. 14 is a schematic view of the assembly, and FIG. 14 is an explanatory diagram of an example of a context suitable for the use example of FIG. BREC: Cell transmission / reception block, BACT: Access block, BT: Processing block, BC: Counter block, MC
T: Processing context memory, MSH: Clock selection module, MMD: Throughput measurement module, MQR:
… Result quantization module, MRR… Result reduction module, MGC… Count management module, MSC …… Determination module.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-109845 (JP, A) JP-A-1-183938 (JP, A) JP-A-1-183939 (JP, A) JP-A-2- 56133 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 11/20 D, G

Claims (21)

(57) [Claims] In order to evaluate the throughput or bit rate of a virtual circuit carrying cells using an asynchronous time division multiplexed transmission channel, a data set called a context defining conditions for evaluating the throughput of the virtual circuit is included. A memory for allocating a storage location to each virtual circuit; and means for reading a context of a virtual circuit to which the cell belongs for each cell reception in order to evaluate a throughput of the virtual circuit, and further expressed in a predetermined unit. A clock signal designed to provide a current time associated with the virtual circuit, wherein upon arrival of one cell of the virtual circuit, one start time indication is provided in the context of the virtual circuit. Written, upon arrival of the next cell of the same virtual circuit, the context is stored from the storage location assigned to the virtual circuit. At this time, the start time read from the context is subtracted from the current time given by the clock signal to calculate a time difference, and the time difference, the cell in which the start time is written, and the next cell A method for evaluating the throughput of a virtual circuit, comprising obtaining a measured value of the throughput of the virtual circuit from the number of time intervals between cells counted between the times of the virtual circuits. 2. A method for evaluating the throughput of a virtual circuit carrying cells using an asynchronous time-division multiplexed transmission channel, comprising the steps of defining a storage location containing a data set called a context defining an evaluation condition of the throughput of the virtual circuit. Means for reading a context of a virtual circuit to which the cell belongs for each cell reception in order to evaluate a throughput of the virtual circuit, using a memory allocated to each virtual circuit, and further comprising a unit expressed in a predetermined unit A method comprising the use of a clock signal designed to provide a current time corresponding to a virtual circuit, wherein each time a cell of the virtual circuit arrives, a start time indication is written into a context of the virtual circuit, and Each time the next cell arrives, the context is read from the storage location assigned to the virtual circuit and is read by the clock signal. From the given current time, the start time read from the context is subtracted to set a time difference, said time difference being defined as the time interval elapsing between two cells and the instant of the virtual circuit being expressed in a predetermined unit. 2. The method according to claim 1, wherein a measurement of the throughput is provided, wherein the measurement of the instantaneous throughput is supplied to an evaluation means for determining the need for a corrective action, and the current time is written in a context as a start time. The method described in. 3. The context includes a count of received cells, and the count is incremented each time a cell of the virtual circuit is received, comparing the incremented count with a specific count to determine a count of received cells. Providing the time difference, defined as the time interval elapsed between two discontinuous cells only when the count value is reached, as a measure of the instantaneous throughput of the virtual circuit, and reinitializing the count of received cells; 3. The method for evaluating the throughput of a virtual circuit using an asynchronous time-division multiplexing transmission channel according to claim 2, wherein: 4. The context includes a start time of a measurement interval, a specific duration of the measurement interval, and the number of received cells, and compares the time difference with the measurement interval duration for each cell reception. Further, when the time difference is smaller than the duration of the measurement interval, the number of the received cells is incremented, and only when the time difference is equal to or longer than the duration of the measurement interval, the incremented number of the received cells is determined. Is provided as a measure of the average throughput of the virtual circuit, defined as the number of cells received at a given time interval, while at the same time the number of received cells and the start time of the measurement interval are re-initialized. A method for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to claim 1. 5. The method according to claim 1, wherein a plurality of throughput measurement values sequentially set for a given virtual circuit are accumulated, and the accumulated value is presented as a measurement value of the accumulated throughput. A method for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to any one of the above. 6. The context includes at least one data item constituting a throughput counter, and adds a difference between a predetermined value corresponding to the allowed throughput expressed in the predetermined unit and one of the measured values of the throughput. 2. The method according to claim 1, further comprising the steps of: correcting the contents of the data; and comparing the arrival position of the throughput counter with respect to the specific end position, and generating a signal indicating the necessity of a correction operation when reaching or passing the end position. 6. A method for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to any one of the above items. 7. A system comprising: a plurality of throughput thresholds and a count value; comparing one of the throughput measurements with the threshold to determine at which interval the measurements are between the thresholds; 6. The method according to claim 1, wherein the count value is corrected according to an interval, and further, a signal indicating a necessity of a corrective operation is supplied by determining that the count value has reached a terminal position in the first direction. A method for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to any one of the preceding claims. 8. The context includes at least one throughput threshold and compares one of the throughput measurements with the threshold and activates a throughput counter in a first direction when the measurement is greater than or equal to the threshold. And when the measured value is smaller than the threshold value, start in the other direction,
6. The apparatus according to claim 1, wherein the throughput counter activated as described above determines that the terminal position in the first direction has been reached, and supplies a signal indicating a necessity of a correction operation. 7. Method of evaluating throughput of virtual circuit using asynchronous time-division multiplexing transmission channel. 9. The context includes a maximum allowed throughput indication, and compares the observed throughput with each maximum cell arrival indication for each cell arrival, and when the observed throughput is equal to or greater than the allowed maximum throughput. 9. The method for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexed transmission channel according to claim 2, wherein the signal indicating the necessity of a correction operation is supplied. 10. When the throughput counter or the count value arrives at a terminal position, a limit throughput value dependent on a corresponding throughput threshold serving the same function as the maximum allowed throughput indication is used in the context. A method for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to claim 9. 11. A memory for allocating a storage location including a data set called a context defining a condition for evaluating a throughput of a virtual circuit to each virtual circuit, and a memory for each cell reception for evaluating the throughput of the virtual circuit. Means for reading the context of the virtual circuit to which the virtual circuit belongs, and a clock signal source designed to supply the current time corresponding to the virtual circuit expressed in a predetermined unit; Means for writing a start time indication to the first virtual cell, means for reading the context from a storage location assigned to the next virtual cell upon arrival of the next cell of the same virtual circuit, and means for reading the current time supplied by the clock signal source. Means for subtracting the start time read by the context, the time difference set by said subtraction, Asynchronous time-division multiplexing, wherein a measured value of the throughput of a virtual circuit is obtained from the number of time intervals between cells counted between the cell in which the writing start time is written and the time of the next cell. For evaluating the throughput of a virtual circuit using a virtualized transmission channel. 12. The means for constructing an instantaneous throughput measurement of a virtual circuit, wherein said time difference is defined as the time interval passing between two cells, and evaluating said instantaneous throughput measurement to determine the need for a corrective operation. 12. The throughput of a virtual circuit using an asynchronous time-division multiplexed transmission channel according to claim 11, further comprising: means for supplying the current time to a context as a start time. Evaluation device. 13. The context includes a count of received cells, means for incrementing the count each time a cell of the virtual circuit is received, and means for comparing the incremented count to a specific count supplied by the context. Providing only the time difference defined as the time interval elapsed between two discontinuous cells as a measure of the instantaneous throughput of the virtual circuit, operating only when the received cell count reaches a specific count value, and 13. The apparatus for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexed transmission channel according to claim 12, further comprising means for re-initializing a cell count. 14. The method of claim 1, wherein the context includes a specific duration of the measurement interval and the number of cells received, and means for comparing the time difference with the duration of the measurement interval for each cell reception; The virtual number defined as the number of cells received in a given time interval, incrementing the number of received cells when the time difference is less than the time and only when the time difference is longer than the measurement interval duration. Means for supplying as a measurement of the average throughput of the circuit, and means for re-initializing the number of cells at the same time, wherein the virtual circuit using the asynchronous time-division multiplexed transmission channel according to claim 12 or 13, comprising: Evaluation device for throughput. 15. The apparatus according to claim 12, further comprising means for accumulating a plurality of said throughput measurement values sequentially set for a given virtual circuit and giving the whole as an accumulated throughput measurement value. Evaluation device for virtual circuit throughput using asynchronous time division multiplexing transmission channel. 16. The context includes at least one throughput counter, means for correcting the contents of said counter by adding a difference between a predetermined value corresponding to an allowed throughput and one of said throughput measurements.
Means for comparing the arrival position of the throughput counter with a specific end position, and generating a signal indicating the necessity of a correction operation when the former is equal to or greater than the latter.
An apparatus for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to any one of 11 to 15. 17. The context includes at least one throughput threshold, means for comparing one of said throughput measurements to said threshold, activating a throughput counter in a first direction above said threshold and in another direction below said threshold. And means for judging that the throughput counter activated as described above has reached the end position in the first direction, and supplying a signal indicating the necessity of a corrective operation. 16. An apparatus for evaluating a throughput of a virtual circuit using the asynchronous time-division multiplexing transmission channel according to any one of items 15 to 15. 18. The method as claimed in claim 18, wherein the context has at least one data item corresponding to a count value and a plurality of throughput thresholds, and wherein the throughput measurement is used to determine at which interval the throughput measurement lies. Means for comparing one of the values with the threshold value, correcting the count value by an amount as a function of the interval determined as described above, and determining and correcting that the count value has reached the end position in the first direction. 16. The apparatus for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexed transmission channel according to claim 11, further comprising means for generating a signal indicating the necessity of an operation. 19. The context includes an allowed maximum throughput indication, comparing the observed throughput with each cell arrival and the maximum throughput indication, and indicating that a corrective action is required if the observed throughput is greater than or equal to the allowed maximum throughput. 19. The apparatus for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexing transmission channel according to claim 12, further comprising means for supplying a signal. 20. Each time the throughput counter or the count value reaches a terminal position, means for writing into the context a limit throughput value dependent on a corresponding throughput threshold value that performs the same function as the permitted maximum throughput indication. 20. The apparatus for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexing transmission channel according to claim 19. 21. The clock signal source supplies a current time corresponding to a virtual circuit via a clock selection module controlled by a clock signal selection indication provided by the context of the virtual circuit, and consequently the master clock. An output group is selected, the least significant bit output characterizing a predetermined unit used for measuring the duration involved in the evaluation of the throughput, and the predetermined unit is selected such that a desired accuracy is obtained in the evaluation value. 21. The apparatus for evaluating a throughput of a virtual circuit using an asynchronous time-division multiplexing transmission channel according to claim 12, wherein the evaluation is performed.