JP2993548B2 - Traffic measurement method and its circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell frame transfer device for transferring an information frame by dividing it into a plurality of cells, transferring the information frame as a single cell, relaying and multiplexing a group of cells.
Alternatively, the present invention relates to a traffic measuring method provided in a system for performing switching and measuring traffic on a line, and a circuit therefor.

[0002]

2. Description of the Related Art Asynchronous transfer mode (Asynchronous Tra)
In a communication network using nsfer mode (ATM), the communication bit rate is determined by using a cell frame transfer method in which an information frame to be communicated is divided into a plurality of fixed-length cells and is transferred (called a cell). Different communications can be handled in a unified manner. In this case, the band used for each communication is determined by the number of cells to be transferred, and the band can be temporally changed in the same communication. Further, as in data communication, a communication mode in which information frames are not always transferred even when a communication channel is set, and cells are transferred in bursts only when there is an information frame to be communicated is conceivable.

In a communication network in which communications having various communication modes are handled in a multiplexed manner, resources for a maximum bandwidth are not always secured for each communication in order to increase the use efficiency of the communication network. Traffic management that secures only resources for an average band corresponding to the actual traffic becomes effective. Under such statistical resource allocation, a congestion state may occur due to the occurrence of bursty information frames in a plurality of communication channels. Therefore, traffic during communication is measured, and based on the measurement result, Therefore, it is necessary to perform resource allocation, facility design, or congestion control. In order to accurately perform these designs and controls, it is important to accurately measure traffic during communication.

[0004] Here, data communication in which an information frame is converted into cells and transferred is considered. As shown in FIG. 5A, a cell group constituting an information frame IF generally includes:
A continuous cell in the same information frame IF, which includes a head cell HC, some intermediate cells MC, and a final cell LC, has a cell transfer rate V ₀ [cell / sec.
c] (this is called a cell interval) T (T =
1 / V ₀ ). The information frame I
As shown in FIG. 5 (b), some of the Fs have a short information frame length so that the information frame IF can be composed of one cell. In this case, the cell is called a single cell SC. I have. When an information frame with a cell transfer rate V ₀ is transferred as a cell over a line with a rate V [cell / sec] (V> V ₀ ), a maximum of N (N = V / V ₀ ) information frames are simultaneously transmitted. Multiple transfer is possible.

In a system that handles such communication, the band in use when n information frames are simultaneously multiplex-transferred can be calculated by the equation (n × V ₀ ). That is, as shown in FIG. 6, n cells are transferred within the time T. Therefore, in order to measure the traffic at the cell level (this is referred to as cell traffic), the number of frames n (N ≧ n ≧
0) should be counted.

FIG. 7 shows a configuration example of a conventional traffic measurement circuit. This traffic measurement circuit includes a cell detection unit 1, a frame number counter 2, and a calculation unit 3. The cell detector 1 detects the arrival of a cell on the line 4 and identifies the type of the detected cell. The information frame is defined in ITU-T standard I.T. A specified by 362, 363
Taking the case where the cell is formed using the TM adaptation layer type 3 as an example, the cell type is identified by the ST field in the cell. With this ST field,
The first cell HC, the intermediate cell MC, the last cell LC, and the single cell SC can be identified. Then, the cell detection unit 1
If the detected cell is the head cell HC, the head cell arrival signal S _HC is output. If the detected cell is the last cell LC, the head cell arrival signal S _LC is output.

[0008] As shown in FIG. 8, when the head cell arrival signal _SHC is supplied, the frame number counter 2
One is added to the count value n, and the final cell arrival signal S _LC
Is supplied, 1 is subtracted from the count value n. Thus, the count value n of the frame number counter 2 indicates the number of frames in which the succeeding cell of the same information frame exists at the point where the value has changed, that is, the number of frames being transferred. Then, the operation unit 3 measures the cell traffic by multiplying the count value n of the frame number counter 2 by the cell transfer speed V ₀ in the information frame.

[0008]

By the way, in the above-mentioned conventional traffic measuring circuit, when the count value n of the frame number counter 2 reaches, for example, k, when the last cell LC arrives, the frame number counter 2 The count value n becomes (k-1), and thereafter, when the leading cell HC arrives within the time T, the count value n of the frame number counter 2 becomes k. Therefore, the arithmetic unit 3 calculates the cell traffic by (k × V ₀ ). However, actually, (k + 1) cells are transferred within the time T, and the actual cell traffic is {(k + 1) × V ₀ }.
The calculation unit 3 underestimates the cell traffic.

When the single cell SC arrives,
Since the first cell arrival signal _SHC and the last cell arrival signal _SLC are simultaneously supplied from the cell detection unit 1 to the frame number counter 2, the counter value n of the frame number counter 2
, The timings of addition and subtraction coincide, and as a result, the frame number counter 2 does not count.

This will be described with reference to FIG. When the last cell LC of the information frame IF ₁ arrives at time t ₁ when the count value n of the frame number counter 2 is 2 (the number of frames being transferred = 2), 1 is incremented from the count value n of the frame number counter 2. It is subtracted to make n = 1. Then, t ₁ + T> to the time t ₂ is t _2, information frame IF ₃
When the first cell HC arrives, 1 is added to the count value n of the frame number counter 2 so that n = 2 again.
However, even if the single cell SC arrives at the time t ₃ where t ₁ + T> t ₃ , since the single cell SC is both the first cell HC and the last cell LC, the first cell arrival signal _SHC and the last cell arrival signal Output _SLC at the same time. The timing of addition and subtraction of the counter value n of the frame number counter 2 coincides with each other, and the count value n of the frame number counter 2 remains at 2.

As described above, the time T ₁ and the time T ₁
, Four cells have actually arrived, and the cell traffic during this period is (4 × V ₀ ), whereas the count value n of the frame number counter 2 is 2 at the maximum. The calculation result of the cell traffic of the calculation unit 3 based on the above is (2 × V ₀ ), which is smaller than the actual cell traffic.

The present invention has been made under such a background, and an object of the present invention is to provide a traffic measurement method and a circuit therefor that can solve the problem of underestimation of traffic and realize highly accurate traffic measurement. I do.

[0013]

According to a first aspect of the present invention, there is provided a traffic measuring method in which an information frame to be communicated is divided into a plurality of fixed-length cells, or a single cell is a continuous cell in the same information frame. The cell is transferred on a line of a predetermined speed at a predetermined time corresponding to a predetermined cell transfer speed, and is used in a cell frame transfer method in which a plurality of information frames are simultaneously multiplexed and transferred on the same line, In the traffic measuring method for measuring traffic on the line, when the arriving cell is a head cell constituting an information frame, 1 is added to a count value of the number of information frames transferred within the predetermined time. If the cell is the last cell constituting the information frame, 1 is subtracted from the count value of the number of frames after the lapse of the predetermined time from the arrival of the cell. And the is characterized by counting the number of frame information frames to be transferred within the predetermined time.

According to a second aspect of the present invention, in the traffic measuring method according to the first aspect of the present invention, when the arriving cell is a single cell, the count value of the number of frames is incremented by one when the cell arrives. And subtracting 1 from the count value of the number of frames after the lapse of the predetermined time from the arrival of the cell. The traffic measurement method according to the third aspect of the present invention is the traffic measurement method according to the first or second aspect, wherein the count value of the number of frames is multiplied by the cell transfer rate of the information frame. It is characterized in that traffic is calculated.

According to a fourth aspect of the present invention, in the traffic measuring circuit, an information frame to be communicated is divided into a plurality of fixed-length cells, or as a single cell, a continuous cell in the same information frame is a predetermined cell. It is transferred on a line of a predetermined speed at a predetermined time corresponding to the transfer speed, and
Used in a cell frame transfer method in which a plurality of information frames are simultaneously multiplexed and transferred on the same line, the arrival of cells on the line and the type of the arriving cell are detected, and the cell is the first cell constituting the information frame. In some cases, a head cell arrival signal is output, and when the cell is the last cell constituting the information frame, a cell detection unit that outputs a last cell arrival signal, and the head cell arrival signal is output from the cell detection unit. A frame number counter for adding 1 to the counted value when supplied, and subtracting 1 from the counted value when the last cell arrival signal is supplied from the cell detector; In a traffic measurement circuit for measuring traffic on a line, after delaying the final cell arrival signal supplied from the cell detection unit by the predetermined time, the frame number counting clock It has a signal timing changing unit that supplies the data, and the count value of the frame number counting counter, characterized in that the number of frame information frame to be transferred on the line within the predetermined time.

According to a fifth aspect of the present invention, in the traffic measuring circuit according to the fourth aspect of the present invention, when the arriving cell is a single cell, the cell detector detects the first cell arriving signal. And outputting the last cell arrival signal at the same time. A traffic measurement circuit according to a sixth aspect of the present invention is the traffic measurement circuit according to the fourth or fifth aspect, wherein a cell value is obtained by multiplying a count value of the frame number counter by the cell transfer rate of the information frame. It is characterized by having an arithmetic unit for calculating the level traffic.

[0017]

According to the first and fourth aspects of the present invention, even if the first cell of the next frame arrives within a predetermined time after the arrival of the last cell of a certain frame, the count value of the number of frames is subtracted as in the related art. Therefore, the number of information frames transferred within a predetermined time is accurately counted. According to the second and fifth aspects of the present invention, when a single cell arrives, 1 is added to the count value of the number of frames during a predetermined time from the arrival of the single cell. , The number of information frames transferred within a predetermined time is accurately counted. Furthermore, according to the third and sixth aspects of the present invention, cell-level traffic is measured with high accuracy.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a traffic measurement circuit according to an embodiment of the present invention. In this figure, the same reference numerals are given to portions corresponding to the respective portions in FIG. 7, and the description thereof will be omitted. In the traffic measuring circuit shown in this figure, a signal timing changing unit 5 is newly provided between the cell detecting unit 1 and the frame number counter 2.

The signal timing changing section 5 is composed of the cell detecting section 1
Cell interval T to the output final cell arrival signal S _LC, corresponding to the last cell LC cell transfer rate V ₀ from the time of arrival from
The frame number is supplied to the frame number counter 2 with a delay. As shown in FIG. 2, the signal timing changing section 5 can be constituted by a shift register having a T-bit width that shifts one bit every one cell holding time.

As shown in FIG. 3, the final cell arrival signal S _LC written in the cell arrival t _a in the shift register shown in FIG. 2 is shifted one bit at a cell suspension time t _CH, time T after the shift register is output as a final cell arrival signal S _'LC is supplied to the frame number counting counter 2. Thereby, the frame number counting counter 2
Time t when the delayed last cell arrival signal _SLC arrives
_b is subtracted from the count value n by one. Further, when the detected cell is the single cell SC, the cell detection unit 1 outputs the first cell arrival signal _SHC and the last cell arrival signal _SLC.
Are output simultaneously.

In such a configuration, the operation of the traffic measuring circuit according to the present embodiment will be described with reference to FIG. When the count value n of the frame number counter 2 is 2
At time t ₁ is a (forward in the number of frames = 2), the last cell LC of information frame IF ₁ arrives, the cell detection unit 1
Detects the last cell LC and detects the last cell arrival signal S _LC
Is supplied to the signal timing changing unit 5.

As a result, the signal timing changing section 5
The final cell arrival signal _SLC supplied from the cell detector 1 is
Since it is supplied to the frame counter 2 with a delay of the cell interval T from the arrival of the last cell LC, the time (t ₁ +
T) until, based on the last cell LC of information frame IF _1, when the count value n of the frame counting counter 2 (now 2) 1 subtraction from not executed.

Next, when the head cell HC of the information frame IF ₃ arrives at time t ₂ where t ₁ + T> t ₂ , the cell detector 1 detects the head cell HC and detects the head cell arrival signal S _{Since HC} is supplied to the frame number counter 2, the frame number counter 2 counts its count value n (currently) based on the head cell arrival signal _SHC supplied from the cell detector 1 as shown in FIG. In the case of 2, 1 is added to 2) to obtain 3.

Next, when the single cell SC of the information frame IF ₄ arrives at time t ₃ where t ₁ + T> t ₃ , the cell detector 1 detects the single cell HC and outputs the first cell arrival signal S _HC and the final cell arrival signal _SLC are output simultaneously,
The signals are supplied to the frame number counter 2 and the signal timing changing unit 5, respectively. Thereby, the frame number counter 2 adds 1 to its count value n (3 in this case) based on the head cell arrival signal _SHC supplied from the cell detection unit 1 as shown in FIG. To 4.

On the other hand, the signal timing change section 5 supplies the last cell arrival signal _SLC supplied from the cell detection section 1 to the frame number counter 2 with a delay of the cell interval T from the arrival of the last cell LC. Therefore, the time (t ₃ +
T) until, based on the last cell LC of information frame IF _3, when the count value n of the frame counting counter 2 (now not executed one subtraction from 4).

At time (t ₁ + T), the signal timing change section 5 supplies the last cell arrival signal _SLC corresponding to the last cell LC of the information frame IF ₁ to the frame number counter 2, and Number counter 2
As shown in FIG. 4, based on the last cell arrival signal _SLC supplied from the signal timing change unit 5, 1 is subtracted from the count value n (4 in this case) to be 3.

Next, at time (t ₃ + T), the signal timing change section 5 sets the single cell S of the information frame IF ₄
Since the final cell arrival signal _SLC corresponding to C is supplied to the frame number counter 2, the frame number counter 2
As shown in FIG. 4, 1 is subtracted from the count value n (3 in this case) based on the last cell arrival signal _SLC supplied from the signal timing change section 5 to obtain 2. Then, the arithmetic unit 3 multiplies the count value n (4 in this case) of the frame number counter 2 within the time T from the time t _{1 by} the cell transfer rate V ₀ in the information frame, thereby obtaining the cell. The traffic (in this case, (4 × V ₀ )) is measured.

As described above, the time T ₁ and the time T ₁
4 cells have actually arrived within the cell, and the actual cell traffic during this time is (4 × V ₀ ), while the time t ₁
The count value n of the number-of-frames counter 2 during the period from to is a maximum of 4, and the calculation result of the cell traffic of the calculation unit 3 based on this value 4 is (4 × V ₀ ), and the actual cell traffic is Can be measured accurately. As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and there are design changes and the like that do not depart from the gist of the present invention. Are also included in the present invention.

[0029]

As described above, according to the present invention,
Even if the first cell of the next frame arrives within a predetermined time after the arrival of the last cell of a certain frame, the counted value of the number of frames is not subtracted, so that underestimation of traffic, which has conventionally been a problem, can be prevented. According to the second and fifth aspects of the present invention, when a single cell arrives, 1 is added to the count value of the number of frames during a predetermined time from the arrival of the single cell. It can be measured. Therefore, accurate traffic measurement can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a traffic measurement circuit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a configuration of a signal timing changing section 5 illustrated in FIG.

FIG. 3 is a diagram for explaining an example of the operation of the signal timing changing section 5 shown in FIG.

FIG. 4 is a diagram for explaining an example of the operation of the frame number counter 2 shown in FIG. 1;

FIG. 5 is a diagram illustrating an example of a case where an information frame is divided into cells and transferred.

FIG. 6 is a diagram illustrating an example of a case where an information frame divided into cells is multiplex-transmitted on a line.

FIG. 7 is a block diagram illustrating a configuration example of a conventional traffic measurement circuit.

8 is a diagram for explaining an example of the operation of the frame number counter 2 shown in FIG. 7;

FIG. 9 is a diagram for explaining a problem of a conventional traffic measurement circuit.

[Explanation of symbols]

 Reference Signs List 1 Cell detection unit 2 Frame number counter 3 Operation unit 4 Line 5 Signal timing change unit

Claims (6)

(57) [Claims] 1. An information frame to be communicated is divided into a plurality of fixed-length cells or, as a single cell, continuous cells in the same information frame are transmitted at predetermined time intervals corresponding to a predetermined cell transfer rate. Transferred over a line of a predetermined speed,
In addition, in the traffic measurement method for measuring traffic on the line, which is used in a cell frame transfer method in which a plurality of information frames are simultaneously multiplex-transmitted on the same line, the arriving cell is a head cell constituting the information frame. In this case, 1 is added to the count value of the number of frames of the information frame transferred within the predetermined time, and if the cell is the last cell constituting the information frame, after the predetermined time elapses from the arrival of the cell. A traffic measurement method, wherein the number of information frames transferred within the predetermined time is counted by subtracting 1 from the count value of the number of frames. 2. When the arriving cell is a single cell, 1 is added to the count value of the number of frames when the cell arrives,
2. The traffic measurement method according to claim 1, wherein 1 is subtracted from the count value of the number of frames after the lapse of the predetermined time from the arrival of the cell. 3. The traffic at a cell level is calculated by multiplying the counted value of the number of frames by the cell transfer rate of the information frame.
Or the traffic measurement method according to 2. 4. An information frame to be communicated is divided into a plurality of fixed-length cells, or as a single cell, continuous cells in the same information frame are transmitted at predetermined time intervals corresponding to a predetermined cell transfer rate. Transferred over a line of a predetermined speed,
In addition, the method is used in a cell frame transfer method in which a plurality of information frames are simultaneously multiplexed and transferred on the same line, and detects the arrival of a cell on the line and the type of the arriving cell. A cell detector that outputs a head cell arrival signal when the cell is a cell, and outputs a final cell arrival signal when the cell is the last cell that constitutes an information frame; A frame number counter for adding 1 to the count value when a signal is supplied, and subtracting 1 from the count value when the last cell arrival signal is supplied from the cell detection unit; In the traffic measuring circuit for measuring traffic on the line, after delaying the last cell arrival signal supplied from the cell detection unit by the predetermined time, A traffic measurement circuit having a signal timing change unit that supplies the number of information frames to the number of information frames transferred on the line within the predetermined time. . 5. The traffic measurement according to claim 4, wherein the cell detector outputs the first cell arrival signal and the last cell arrival signal simultaneously when the arrival cell is a single cell. circuit. 6. The arithmetic unit according to claim 4, further comprising an arithmetic unit for calculating cell-level traffic by multiplying a count value of the frame number counter and the cell transfer rate of the information frame. The described traffic measurement circuit.