JP3074918B2 - Cell traffic monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for packet communication. In particular, the present invention relates to a technique for monitoring traffic of a cell transferred in a packet communication network (in this specification, a fixed-length packet is referred to as a “cell”).

[0002] The present invention relates to policing, in which a cell is transmitted as a breach of contract when the cell is transmitted in excess of pre-contracted traffic.
Use for

[0003]

2. Description of the Related Art In a packet communication network, if a large number of cells arrive at one relay point at a time, smooth operation cannot be performed. For this reason, the telecommunications carrier that operates the packet communication network must make sure that the user does not transmit more than n cells within m consecutive cell hours in the contract with the user,
The telecommunications carrier makes it a condition of the usage contract to discard the transmitted cell in violation of this. For example, if m = 5 and n = 3, 3
Although cells can be transmitted, if cells are transmitted beyond this, the cells will be discarded. Monitoring and discarding for this purpose is called policing, and is performed automatically and continuously at the entrance of the packet communication network.

FIG. 7 is a block diagram of a conventional apparatus. This circuit has been applied for a patent application (Japanese Patent Application No. 2-1).
No. 30464). The circuit shown in FIG. 7 is a circuit that can transmit up to three cells in five consecutive cell times, but monitors not to allow more than four cells.

In FIG. 7, a monitored signal is input to a terminal 1.
The cell detection circuit 2 synchronizes with the monitored signal and sends out a detection output when there is a valid cell in the signal. The delay circuit 3 receives this detection output as an input, and is constituted by a shift register. The delay circuit 3 is shifted rightward in the figure by one stage every one cell time by a clock signal (not shown). That is, the delay circuit 3 has its input sent to the delay output after m cell times. The detection output of the cell detection circuit 2 is input to the addition input of the up / down counter 4, and the delay output of the delay circuit 3 is input to the subtraction input. Threshold memory 5
Holds the threshold value n set by the contract. The threshold value n is compared with the content D of the up / down counter 4. If D> n, a decision output 7 is sent out, and the violating cell is discarded by the cell discarding control unit 8.

In the circuit thus constructed, the number of cells detected in the past m cell times is stored in the up / down counter 4, and when this exceeds the set threshold value n, The judgment output 7 is sent to the cell discard control unit 8. At the same time, the value of the first stage of the delay circuit 3 is cleared by the judgment output 7.

Although FIG. 7 described the hardware configuration of the cell traffic monitoring device in an easy-to-understand manner, a practically equivalent circuit is incorporated in a microprocessor, and the delay circuit 3 and the delay circuit 3 are controlled by a program. It is configured so that the contents of the memory area corresponding to the up / down counter 4 can be rewritten and executed. Moreover, in the configuration controlled by the microprocessor, such a cell traffic monitoring device can be configured by using one processor in common for not only one channel but also a plurality of channels or virtual paths (virtual paths). . In such a case, for a number of time-division multiplexed cells, a virtual path number (in this specification, V
PI (called Virtual Path Identifier)
The VPI can be identified and monitored for each VPI. Further, in this case, only by devising software for controlling the program, it is possible to set different contract conditions for each VPI, for example, the above-mentioned m value and n value as individual conditions. This was also disclosed in the applicant's prior application (Japanese Patent Application No. 2-319735, not disclosed at the time of filing the present application).

[0008]

As described above, a large number of VPs
When the cell traffic monitoring for each VPI is performed by one device for the time-division multiplexed signal for I, there is no need to provide a cell traffic monitoring device for each user line, and only one device is provided for the multiplexed signal path. It is extremely economical to install a cell traffic monitoring device, but here the inventors encountered the following problem.

[0009] That is, even if each line user is transmitting a cell correctly at its terminal so as to conform to the above-mentioned contract conditions, time division multiplexing for a plurality of lines will result in signal multiplexing. Because of the queuing, if cell traffic monitoring is performed with time-division multiplexed signals, cells may be discarded as transmitted in violation of contract conditions.

In general, when multiplexing a plurality of digital signals, a FIFO (first-in first-out) memory is used as a buffer circuit in a multiplexing circuit, and even if cells are input simultaneously from many low-speed input lines in a short time. Are temporarily stored in a buffer circuit, and the contents of the buffer circuit are read out and multiplexed according to a high-speed clock signal on the multiplex output side. At this time, individual cells need to wait in the buffer. Therefore, when looking at the line of one user, the cell time interval of the user is not necessarily the transmitted time interval on the multiplexed signal. In other words, focusing on one VPI from the multiplexed signal,
When the cell is detected and its occurrence is monitored as described in the circuit of the above-described conventional example, a case may occur where the line of the user matches the contract condition but the monitoring point does not match. This problem occurs not only when monitoring is performed by using multiplexed signals, but also when a monitored signal passes through a store-and-forward operation that has a waiting time. Also, the user performs transmission control, but the performance is controlled by the network UPC (Usage Parameter).
Control) performance is not high enough,
It is practically conceivable to cause a slight violation due to a frequency shift between the network and the user.

The present invention has been made in such a background, and does not immediately output a determination signal even when it is determined that a violation has occurred. It is intended to provide a cell traffic monitoring device that discards only cells.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for determining whether a cell, which is installed in an asynchronous communication network and has been identified for each user, is transmitted from the user beyond the contract conditions with the user. In a traffic monitoring device that monitors whether or not the received cell exceeds the contract condition and discards the transmitted cell, temporarily discards the cell that is determined to be discarded in accordance with the contract condition. Means for suspending, and a cell temporarily suspended by the means is further determined under a second condition different from the contract condition, and a cell satisfying the second condition is temporarily suspended by the means. Means for canceling the discarded cell.

It is preferable that the means for canceling the cell discarding has a control terminal for enabling or disabling the means.

[0014] The second condition is that transmission of cells violating the contract condition is repeated a predetermined number of times within a fixed time, and that n times within m cell times when the contract condition continues.
When not transmitting more than n 'cells during a particular number of consecutive m-cells, when not transmitting more than n' cells during a particular consecutive time period. It is desirable that the ratio of the cell violating the contract to the cell not violating the contract condition is equal to or less than a predetermined value.

[0015] By means of a buffer or the like inserted in the transmission path,
In order to prevent discard of cells that are deemed to be unintentionally apparently violating cells, the criteria are given a certain tolerance range. Counts and expands the allowable range. Uses a shift register instead of the counter to expand the allowable range. Stops discarding cells while the control signal is being input by an external control signal. There is a method of using a CPU that calculates the violation rate from the number of passing cells and the number of violating cells, discarding cells with the violation rate as a threshold.

[0016]

The regularity of the cell interval transmitted by the user is converted by a buffer inserted in the transmission line of the carrier. The expected maximum delay time received by cells temporarily stored in the buffer due to signal queuing can be said to be the maximum delay time of the buffer. In order to rescue the delayed cell from the violation determination, the number of violation determinations is counted by a counter or a shift register and compared with a second threshold value that has set an allowable range, or an allowable violation rate (number of violating cells) / Number of passing cells) is set as a second threshold, and the number of passing cells and the number of violating cells are individually counted, calculated, and compared with the second threshold. Further, an external control terminal may be provided to stop the discard of the offending cell from outside.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of the first embodiment of the present invention. FIG. 2 is a diagram showing the internal configuration of the discard determination unit according to the first embodiment of the present invention.

According to the present invention, a cell installed in an asynchronous communication network is monitored for whether or not a cell identified by each user is transmitted from the user beyond the contract conditions with the user. A counter as means for temporarily suspending the discard of a cell determined to be discarded in accordance with the contract condition in a traffic monitoring device that discards a transmitted cell when it is determined that the condition is exceeded. 21 and a cell temporarily held by the means is further determined under a second condition different from the contract condition, and a cell satisfying the second condition is temporarily held by the means. A second comparison / determination unit as means for stopping cell discarding.

Next, the operation of the first embodiment of the present invention will be described. Except for the addition of the discard determination unit 10, the configuration is the same as that of the conventional device described above, and the description of the operation of the portions described in the conventional device is omitted. The signal determined to be in violation by the first comparison / determination unit 6 counts up the counter 21, and the second threshold stored in the second threshold memory 24 is compared with the value of the counter 21. . If the value of the counter 21 is larger than the second threshold, the second comparison / determination unit 23 outputs a cell discard signal to the cell discard control unit 8 and discards the cell. The value of the second threshold value and the value of the counter reset cycle timer 22 are determined in consideration of the nature of the traffic and the magnitude of the fluctuation of the user-side transmitting device. In the first embodiment of the present invention, if the transmission of the cell violating the contract condition is repeated within a predetermined time set in the reset period timer 22 within a range not exceeding the second threshold value, the cell is discarded. It is to stop.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram illustrating the internal configuration of the discard determination unit 10 according to the second embodiment of the present invention. The signal determined to be in violation is stored in the shift register 25. Assuming that the length of the shift register 25 is the maximum delay time (referred to as CDV) by a buffer or the like inserted in the transmission path, the violation determination signal is added by the length of the shift register 25,
The determination signal having passed the time longer than the length is output to the discard control unit 8 as it is. Assuming that the declared values are n within m cell time, the second threshold value = CDV · n / m. In other words, this indicates that there is a possibility that the number of cells arriving in the CDV section is violated. This invention
The second embodiment can be considered to have a configuration in which the circuit shown in the conventional example is further added by one stage. That is, when the contract condition is not to transmit more than n cells within consecutive m-cell times, transmission is performed over n 'cells greater than n within a specific continuous m-cell time. If not,
This is to stop cell discarding.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a configuration diagram of the third embodiment of the present invention. The determination signal from the first comparison determination unit 6 is input to the AND circuit 26. The other input of the AND circuit 26 is connected to a discard ON / OFF bit circuit 27. The discard ON / OFF bit circuit 27 controls an ON / OFF bit input to the AND circuit 26 by a control input from the control terminal 11. . When the determination signal is input to the AND circuit 26, the determination signal is output to the cell discard control unit 8 if the ON bit is input to the AND circuit 26, and the determination is performed if the OFF bit is input to the AND circuit 26. The signal is not output to the cell discard control unit 8. Thus, the control terminal 1
With the control signal from No. 1, the discard of the offending cell can be externally controlled by the congestion state of the network. The external control method using the control terminal 11 may be adopted in combination with other embodiments of the present invention.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram of the fourth embodiment of the present invention. FIG. 6 is a diagram showing the internal configuration of the discard determination unit 10 according to the fourth embodiment of the present invention. Here, the number of cell arrivals is input from the up / down counter 4 to the CPU 29, the number of violating cells is input from the counter 21 of the discard determination unit 10 to the CPU 29, and the following calculation is performed: violation rate = number of violating cells / number of passing cells. If the violation rate ≧ the second threshold value, a discard signal is output to the cell discard control unit 8. That is, the fact that only one connection does not have a large violation rate and that almost all connections have the same violation rate in a steady state is used. In the fourth embodiment of the present invention, if the ratio of cells that violate the contract conditions to cells that do not violate the contract conditions within a specified continuous time is equal to or less than a predetermined value, the discarding of the cells is stopped.

[0023]

As described above, the present invention does not immediately output a determination signal even when it is determined that a violation has occurred, and can discard a cell only when there is a certain amount of delay and it is clearly considered to be a user violation. . When a violation is determined, the cell is not immediately discarded, but is held for a certain period of time.
It is possible to cope with the disorder of cell arrival due to the transmission problem of the carrier.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a discard determination unit according to the first embodiment of the present invention.

FIG. 3 is an internal configuration diagram of a discard determination unit according to a second embodiment of the present invention.

FIG. 4 is an internal configuration diagram of a discard determination unit according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 6 is an internal configuration diagram of a discard determination unit according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional device.

[Explanation of symbols]

 Reference Signs List 1 terminal 2 cell detection circuit 3 delay circuit 4 up / down counter 5 first threshold memory 6 first comparison / judgment unit 7 judgment output 8 cell discard control unit 9 cell discard terminal 10 discard judgment unit 11 control terminal 21 counter Reference Signs List 22 reset cycle timer 23 second comparison / determination unit 24 second threshold memory 25 shift register 26 AND circuit 27 discard ON / OFF bit circuit 29 CPU

Continuation of the front page (56) References JP-A-5-191428 (JP, A) JP-A-4-156026 (JP, A) JP-A-5-136811 (JP, A) "ATM network traffic by deterministic UPC" Management Method ”IEICE Tech. CS 91-89 (Heisei 3-10-18) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04L 12/28

Claims (3)

(57) [Claims] 1. A cell installed in an asynchronous communication network and monitoring whether a cell transmitted from a user exceeds a contract condition with the user for a cell identified for each user, and checks the contract condition. A traffic monitoring device for discarding a transmitted cell when it is determined that the number of cells exceeds the threshold value; a means for temporarily suspending the discard of a cell determined to be discarded in accordance with the contract conditions; predetermined violation determination number of times within a predetermined time separately from the further the terms for temporarily reserved cell
Whether or not the number of times exceeds the number of times is set as a second condition, a determination is made based on the second determination condition, and for a cell satisfying the second condition, discarding of the cell temporarily held by the means is performed. A cell traffic monitoring device comprising: means for canceling the cell traffic. 2. A cell installed in an asynchronous communication network and monitoring whether or not a cell transmitted from a user exceeds a contract condition with the user for a cell identified for each user, and checks the contract condition. A traffic monitoring device for discarding a transmitted cell when it is determined that the number of cells exceeds the threshold value; a means for temporarily suspending the discard of a cell determined to be discarded in accordance with the contract conditions; For a temporarily suspended cell, a predetermined contract breach rate is set as a second determination condition separately from the contract conditions, and for a cell satisfying the second determination condition, the cell is temporarily suspended by the means. Means for canceling the discard of a cell that has been discarded. 3. A cell installed in an asynchronous communication network and monitoring whether a cell transmitted from a user exceeds a contract condition with the user for a cell identified for each user and checks the contract condition. A traffic monitoring device for discarding a transmitted cell when it is determined that the number of cells exceeds the threshold value; a means for temporarily suspending the discard of a cell determined to be discarded in accordance with the contract conditions; Further, a determination is made on the temporarily reserved cell under a second condition different from the contract condition, and for the cell satisfying the second condition, the discarding of the temporarily reserved cell by the means is stopped. Means for stopping cell discarding, the control means for enabling or disabling the means. Place.