JP2580395B2 - Cell monitoring device and cell flow control device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring and controlling traffic for a value declared by a user in an ATM switching system.

[0002]

2. Description of the Related Art ATM and ATM
(Asynchronous Transfer Mode) The exchange method divides communication information into fixed-length cells, stores them, and transmits them using optical transmission lines while switching the cells at high speed with hardware, thereby achieving high efficiency and large capacity. This is an exchange method that enables information transmission.

[0003] In the ATM switching system, multimedia information can be transmitted, so that various information having different use bands (communication speeds) and burst characteristics are transmitted. For this reason, if unrestricted information transmission is allowed, local concentration of traffic will be caused, causing a remarkable reduction in transmission performance and possibly adversely affecting the service quality of other users. Therefore, in the ATM switching system, a user using a transmission line declares traffic to a network at the time of making a call, and the network performs call acceptance control based on the declared value. That is, at the entrance of the network, it is monitored whether the traffic of each call does not exceed the declared value, and if it exceeds the declared value, it is necessary to perform flow control such as forcibly discarding cells. In this case, the monitoring items generally include the maximum speed / average speed of the cell or the burst duration (maximum speed duration).

[0004] As a first conventional method of monitoring and controlling traffic (a so-called policing function) for a value reported by a user as described above, cell flow is compared with the number of arriving cells within a unit observation period. There is a monitoring method. FIG. 11 is an explanatory diagram in the case where such a conventional method is applied to monitoring the maximum speed of a cell. As can be seen from the figure, if more cells than the specified value (C = 1) arrive at the exchange within the period (T) calculated from the maximum speed declared by the user, the cells will declare the declared traffic. It is determined that the violating cell is over. Specifically, first, a call (channel) is identified by a VCI (Virtual Channel Identifier), which is address information added to a cell header, a cell counter is set for each VCI, and The cycle (T) is calculated from the maximum speed declared by the corresponding user, and the specified value (C
= 1) is set. Then, the cell counter corresponding to each VCI is reset every period (T) corresponding to each VCI, and is counted up each time a cell having each VCI arrives. As a result of counting up at each arrival point,
If the counter value exceeds a specified value (C = 1), it is determined that the cell is a violation cell.

[0005] In this way, the cell determined to be a violating cell is discarded, or a mark indicating violation is given. Note that C is an appropriate large number (for example, 100
As 0), if the time specified for the C count calculated from the average speed reported by the user is T, the average speed can be monitored.

Here, UNI (User Network Interface)
On a so-called subscriber line), the VCI added to the cell header is generally 16 bits and 30 bits in total including the VPI (Virtual Pass Identifier) which is a part of the address information. 2 ²⁰ cell counters are required. Therefore, a method of configuring a cell counter with a memory is practical, but in this method,
As described above, since it is necessary to reset the counter every period (T) calculated from the maximum speed reported by the user, the memory is accessed several times within one cell hold time corresponding to the maximum speed of the transmission line. Depending on whether it is possible, the number of calls that can be multiplexed is determined. As described above, since the number of cell counters needs to be 2 ¹⁶ to 2 ²⁰ , the memory used is assumed to be a CMOS memory. Since the access time of the CMOS memory is limited to about 85 ns (nanosecond), as shown in FIG. 12, one cell hold time defined as the ATM switching method is 2.7 μs (transmission speed is 15 μs).
6 Mb / s (megabits / second)) STM-1 line has about 32 multiplexes, and 1 STM-1 line has higher speed than STM-1 line.
The cell hold time is 680 ns (the transmission speed is 622 Mb /
In the STM-4 line of s), the limit is about eight multiplexes.

As described above, in the first conventional example, the number of simultaneously accessible cell counters is far smaller than the total required number of cell counters. Actually, it is rare that the cell counters corresponding to all the VCIs are reset at the same timing. However, if the number of the cell counters for which the reset operation is performed at the same time is as small as the above-described multiplicity, the cell counter becomes practical. There is a problem that the system cannot be configured.

In contrast to the first conventional example as described above, FIG.
A second conventional example such as No. 3 has also been proposed. In this conventional example, the flow rate of cells is monitored by comparing the number of arriving cells within a unit observation cycle, and the first conventional example (in the case of FIG. 11) is used until the number of arriving cells is counted by a cell counter.
Is the same as The second conventional example is different from the first conventional example in that a cell counter having a fixed reset period is provided in a memory in advance, and an optimum counter is selected based on a value declared by a user at the time of call setting. different.

More specifically, as shown in FIG. 13, the period (T) corresponding to the maximum speed of the transmission line is τ, one cell counter having a period of 2 ⁰ τ (No. 1), and a period of 2 ¹ τ Cell counters are 2 ¹ = 2 (No. 1 and No. 2), and the period is 2 ² τ
Cell counters are 2 ² = 4 (No. 1 to No. 4),
..., the cell counter of the period 2 ^n-1 τ is 2 ^n-1 or (N
o. 1 to No. 2 ⁿ -1), a total of 2 ⁿ -1 cell counters are allocated on the memory. Then, a cell counter having a cycle closest to the cycle (T) calculated from the maximum speed declared by the user is selected and associated with each VCI for which a call is set.

Here, a cell counter corresponding to each VCI
Counts up each time a cell with that VCI arrives
This is the same as in the first conventional example. one
On the other hand, the reset operation of the cell counter
Is incremented by a cycle (T = τ) corresponding to
Imming 0, 1, 2, ... 2,^n-1-1, 2^n-1, 2
^n-1Each cell cow shown in FIG.
This is realized as an operation of resetting the counter. For example,
At timing 2 in FIG.⁰No. of τ. 1 mosquito
Counter and cycle 2¹No. of τ. 1 counter and period 2
^TwoNo. of τ. 3 counters,..., Cycle 2^n-1τ
No. The counter of 3 is reset.

As can be seen from FIG. 14, in the second conventional example, each has a period of 2 ⁰ τ, 2 ¹ τ, 2 ² τ,.
A total of n counters are reset at the same timing for each cell counter having 2 ^n-1 τ. Here, when the cell counter is provided on the CMOS memory, as described above (see FIG. 12), in the STM-1 line, 32 times within one cell holding time (= τ) corresponding to the maximum speed of the transmission line. 1 is possible in the STM-1 line.
It is possible to provide 2 ³² -1 cell counters from 3;
The multiplex processing of the number of calls corresponding to the number is possible, and it is possible to sufficiently cope with all the necessary numbers of the cell counters described above.

However, as described above (see FIG. 12),
STM-4 lines in one cell holding time corresponding to the maximum speed of the transmission path (= tau) for access number is eight possible within, STM-4 lines in the 2 ⁸ -1 cell counter than 13 However, this is not enough for the required number of cell counters described above.

Further, in the case of the second conventional example, when selecting a cell counter from a user's declared value at the time of call setup, it is necessary to determine which counter in each cycle can be used,
Therefore, it is necessary to manage the closed state of the counter,
Processing becomes complicated. In addition, as shown in FIG.
There is a problem that there is a high possibility that a counter with an optimal cycle cannot be selected because the cycle that can be set in the cell counter is limited and the number of counters with a short cycle is small. SUMMARY OF THE INVENTION It is an object of the present invention to enable a multiplexing process corresponding to the required number of VCIs without any limitation on the period that can be set in the cell counter, without the need to manage the closed state of the counter.

[0014]

FIG. 1 is a block diagram showing the principle of the present invention, and is an example of a cell monitoring apparatus for monitoring an average cell speed on a subscriber interface of an ATM switching system.

The reference time data generating means 101 generates reference time data tn. Time data storage means 103
Stores time data tB corresponding to each call (VCI, etc.). Then, when the cell arrives, the gate signal 10
When 2 is input, the time data tB in the storage means 103 corresponding to the call of the arriving cell is rewritten with the reference time data tn generated from the reference time data generation means 101.

The subtraction means 104 calculates the time data corresponding to the call of the arriving cell stored in the time data storage means 103 from the reference time data tn generated from the reference time data generation means 101 at the arrival timing of the cell. tB
Is subtracted. As a result, the cell arrival interval Tn, which is the time interval from the rewriting time of the previous time data corresponding to the call of the arriving cell in the time data storage means 103 to the arrival time of the current cell, is measured.

The cell arrival interval prescribed value storage means 105 stores a cell arrival interval prescribed value T corresponding to each call calculated based on the average cell speed declared by the user when each call is set up.

The first comparing means 106 determines the cell arrival timing Tn corresponding to the call of the arriving cell measured by the subtracting means 104 and the arrival time stored in the cell arrival interval prescribed value storage means 105 at the arrival timing of the cell. A cell arrival interval specification value T corresponding to a cell call is compared. When the cell arrival interval Tn is equal to or longer than the cell arrival interval prescribed value T, the gate signal 102 is output.

The cell counter 107 stores a cell counter value Ca corresponding to each call. Then, at the arrival timing of the cell, the cell counter value Ca corresponding to the call of the arriving cell is determined when the first comparing means 106 determines that the cell arrival interval Tn is equal to or greater than the specified cell arrival interval T. It is reset, and is incremented by 1 when it is determined that the cell arrival interval Tn is smaller than the cell arrival interval prescribed value T.

The specified cell number storage means 108 stores a specified cell number value C corresponding to each call calculated based on the average cell speed declared by the user when each call is set up. Then, the second comparing means 109 determines whether or not the cell counter value Ca corresponding to the call of the arriving cell stored in the cell counter means 107 is stored in the specified cell number storage means 108 at the arrival timing of the cell. A comparison is made as to whether or not a cell number prescribed value C corresponding to a cell call is exceeded. As a result, if it exceeds, it is determined that the arriving cell is a cell that violates the average speed report.

In the configuration of the above-described invention, when the cell arrival interval prescribed value storage means 105 is provided, the cell number prescribed value C is not calculated based on the average cell speed declared by the user. A fixed value may be used in common for all calls, in which case the cell number prescribed value storage means 108 is not required.

Conversely, the cell number prescribed value storage means 108
Is provided, the cell arrival interval prescribed value T is not calculated based on the average speed of the cell declared by the user, but may be a fixed value common to all calls. The arrival interval prescribed value storage means 105 is not required.

Further, an ATM similar to that of FIG.
It is also possible to implement a cell monitoring device that monitors the maximum cell speed on the switching system subscriber interface. In this case, the subtraction means 104 measures the one-cell arrival interval, which is the time interval from the arrival time of the previous non-violating cell corresponding to the call of the arrival cell to the arrival time of the current cell. Then, the cell arrival interval prescribed value storage means 1 of FIG.
Reference numeral 05 denotes a one-cell arrival interval prescribed value storage means, which stores a one-cell arrival interval prescribed value corresponding to each call calculated based on the maximum speed of the cell declared by the user when setting each call. I will remember. Then, all the values 1 are stored in the cell number prescribed value storage means 108 (therefore, the same means is not substantially necessary), whereby the second comparing means 109 determines whether the cell arrives at the cell arrival timing. A comparison is made as to whether the cell counter value corresponding to the call of the arriving cell stored in the counter means 107 exceeds 1, and if the cell counter value exceeds 1, it is determined that the arriving cell is a cell violating the declaration of the highest speed. It will be determined.

FIG. 2 is a block diagram showing the principle of FIG.
When operating as a cell monitoring device to monitor the maximum speed of the cell as described above, further, when the function of monitoring the burst duration, which is the time the cell continuously inputs at the maximum speed, is added, FIG. 3 is a block diagram of a part of the present invention that realizes the function.

In FIG. 2, a second time data storage means 110 stores second time data tB corresponding to each call. When the first comparing means 106 in FIG. 1 determines that the one-cell arrival interval Tn is larger than the one-cell arrival interval specified value T at the cell arrival timing, the storage corresponding to the call of the arriving cell is performed. The second time data tB on the means 110 is the same as the reference time data generating means 101 in FIG.
Is rewritten with the reference time data tnB generated from.

The second subtraction means 111 calculates the arrival time of the cell from the reference time data tnB generated by the reference time data generation means 101 in FIG. The second time data tB corresponding to the call of the cell is subtracted. Thereby, the burst duration TnB corresponding to the call of the arriving cell is measured.

Burst duration specified value storage means 112
Stores a burst duration specified value TB corresponding to each call, which is calculated based on the burst duration of the cell declared by the user when setting each call.

Then, the third comparing means 113 stores the burst duration TnB corresponding to the call of the arriving cell measured by the second subtracting means 111 in the burst duration specified value storing means 112 at the cell arrival timing. A comparison is made as to whether the stored burst duration prescribed value TB corresponding to the call of the arrival cell is exceeded. As a result, if it exceeds, it is determined that the arriving cell is a cell that violates the declaration of the burst duration.

Although not specifically shown, the present invention further provides a method for monitoring the average speed, the maximum speed, or the burst duration of a cell as described above, based on the monitoring result of a cell monitoring device. A cell flow control device having a cell flow control means for controlling the flow can be realized. Specifically, the cell flow rate control means is the second comparison means 1 of FIG.
09 outputs a determination that it violates the declaration of the average or maximum speed of the cell, or when the third comparison means 113 in FIG. 2 outputs a determination that it violates the declaration of the burst duration of the cell. , Forcibly discarding the arrival cell corresponding thereto, or giving a mark indicating that a violation has occurred in the cell.

[0030]

As can be seen from FIG. 1, in the present invention, the cell counter value Ca of the cell counter means 107 is not reset at once for each cycle T calculated from the declared value of the user. Subtraction means 10 each time a cell arrives
4, the cell arrival interval Tn is calculated, and if the cell arrival interval Tn is equal to or greater than the cell arrival interval prescribed value T set in advance by the first comparing means 106, one cell counter value Ca corresponding to the call is obtained. Only reset. In the time data storage means 103 as well, only one time data tB corresponding to the call of the arriving cell is updated as needed only at the timing at which the cell arrives.

That is, since the number of accesses to the memory within one cell hold time does not depend on the number of calls to be multiplexed, there is no limit to the number of calls that can be multiplexed as long as the memory capacity permits. Therefore, not only the STM-1 line but also the STM-4 line with one cell hold time of 680 ns can be processed with sufficient margin. Further, unlike the second conventional example described above, there is an advantage that there is no limitation on the value of the monitoring period T set based on the user's declared value, and it is not necessary to manage the closed state of the cell counter.

Further, in the configuration shown in FIG. 2, the burst duration can be monitored with a sufficient margin, similarly to the operation principle shown in FIG. By using these cell monitoring devices, it is possible to realize a cell flow control device capable of appropriately performing cell flow control such as cell discarding or marking.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 3 is a basic configuration diagram of the embodiment of the present invention.

First, in the dropper 301, a 24-bit address portion including VPI and VCI is extracted from the header of the cell input from the UNI, and the latch 30
2 is held. The VPI + VCI address data is further converted to 16-bit address data (hereinafter, simply referred to as VCI) in the VCI conversion unit 303.
In particular, the communication path (not shown) is controlled and newly added to the header of the cell, and is also input to the maximum / average speed monitoring unit 306 particularly related to the present invention.
It should be noted that, without providing the VCI conversion unit 303, a 24-bit V
The configuration may be such that PI + VCI data is directly input to the maximum / average speed monitoring unit 306.

The input cell is subjected to timing correction in the delay buffer 304. The maximum / average speed monitoring unit 306
For each VCI detected from the VCI conversion unit 303,
It monitors each maximum or average speed of each cell with CI.

The burst duration monitor 307 has the highest
Based on the determination result of the average rate monitoring unit 306, the burst duration, which is the time during which cells continuously enter at the maximum rate, is monitored.

If the maximum / average rate monitoring section 306 determines that the maximum or average rate of the cell corresponding to each VCI violates the declaration of the user corresponding to the VCI, Alternatively, when the burst duration monitoring unit 307 determines that the burst duration of the cell corresponding to each VCI violates the report of the user corresponding to the VCI, the processing for forcibly discarding the cell corresponding to the VCI. Alternatively, a process of adding a mark indicating that a violation has occurred to the cell is performed.

The cells output from the marking / cell forcible discarding unit 305 are switched by an ATM switch (not shown). FIG. 4 shows the maximum / average speed monitor 3 of FIG.
FIG. 6 is a block diagram of the present invention, particularly relating to the present invention. In the figure, the address corresponding to each VCI of the time storage table 401 constituted by the CMOS memory is
Time data tB for each I is stored. Reference counter 40
2 generates reference time data tn (reference time). The subtraction circuit 403 calculates tn-tB every time a cell arrives. An address corresponding to each VCI in the cell arrival interval prescribed value table 404 constituted by the CMOS memory XX is provided with a cell arrival interval prescribed value T for each VCI set by software processing based on a user's declared value. Is stored. When the cell arrives, the comparison circuit 405
The cell arrival interval Tn from the cell arrival interval 03 and the cell arrival interval prescribed value T from the cell arrival interval prescribed value table 404 are compared, and a corresponding judgment output is output. The AND circuit 406 stores the output of the reference counter 402 in the time storage table 401 when the determination output of the comparison circuit 405 satisfies Tn ≧ T.

On the other hand, the cell counter value Ca of each VCI is stored in the address corresponding to each VCI of the cell counter 407 constituted by the CMOS memory. , And is reset when Tn ≧ T. C
The address corresponding to each VCI in the cell number specification value table 408 constituted by the MOS memory stores a cell number specification value C for each VCI set by software processing based on a user's declared value. Comparison circuit 40
9 compares the cell counter value Ca from the cell counter 407 with the specified cell number C from the specified cell number table 408 when the cell arrives, and outputs the violation determination output of FIG. Output to the mark assignment / cell forced discard unit 305.

FIG. 5 is a block diagram showing the burst duration monitoring unit 3 shown in FIG.
07 is a configuration diagram. 3, a time storage table 501 and a reference counter 502 have the same configurations as the circuits 401 and 402 in the maximum / average speed monitoring unit 306 in FIG. 4, respectively, but the maximum / average speed monitoring unit in FIG. When the judgment output of the comparison circuit 405 of T 306 is Tn> T, the AND circuit 506 is turned on and the reference counter 5
02 is stored in the time storage table 501. Note that the reference counter 502 is a reference counter 4
02 and a common counter. Subtraction circuit 503
Subtracts the time data tBB of the time storage table 401 from the reference time data tnB of the reference counter 502 every time a cell arrives, and outputs the result as a burst duration time TnB. CMO
At the address corresponding to each VCI in the burst duration prescribed value table 504 composed of the S memory, a burst duration prescribed value TB for each VCI set by software processing based on a user declared value is stored. You.
The comparison circuit 505 compares the burst duration TnB from the subtraction circuit 503 with the specified burst duration value TB from the specified burst duration value table 504, and TnB> TB.
In this case, a violation determination output is output to the mark assignment / cell forced discard unit 305 in FIG.

The operation of the embodiment having the configuration shown in FIGS. 3 to 5 will be sequentially described. First, the operation when the maximum speed is monitored by the maximum / average speed monitoring unit 306 in FIG. 3 will be described.

In the case of maximum speed monitoring, the user declares the maximum speed when calling. Then, the cell number specification value C = 1 is stored in the address corresponding to the user's VCI in the cell number specification value table 408 in FIG. The address corresponding to the VCI of the user in the cell arrival interval prescribed value table 404 is calculated based on the reported value of the maximum speed from the user by software processing of an ATM call control processor (not shown). One cell arrival interval is stored as the cell arrival interval prescribed value T.

Thereafter, in the actual communication phase, a maximum speed monitoring operation is performed by the maximum / average speed monitoring unit 306 in FIG. That is, for example, when a cell arrives at the timing of certain reference time data tn1 as shown in FIG.
First, the VCI of the cell is detected via the circuits 301, 302, and 303 in FIG. 3, and the addresses of the time storage table 401 and the cell arrival interval prescribed value table 404 in FIG.

Based on this address designation, the subtraction circuit 403 of FIG. 4 uses the reference time data tn1 of the reference counter 402 at the time of cell arrival to read the previous time stored at the designated address (= VCI) of the time storage table 401. The cell arrival interval Tn1 (actually measured value) is calculated by subtracting the time data tB1 at the time of arrival of the non-violating cell (this storing operation will be described later).

Subsequently, when the cell arrives, the comparison circuit 405 determines the cell arrival interval Tn (actually measured value) and the specified address (= VCI) of the cell arrival interval prescribed value table 404.
Is compared with the specified value T (calculated value) of the cell arrival interval, and a result of the determination of Tn> T, Tn = T, or Tn <T is output. In the example of the timing of the reference time data tn1 in FIG. 6, Tn1> T. In this case, the AND circuit 406 is turned on, and the reference time data tn1 of the reference counter 402 at that time is newly stored again as time data tB2 at the designated address (= VCI) of the time storage table 401. At the same time, the cell counter value Ca of the designated address (= VCI) of the cell counter 407 becomes "1".
Is reset to Then, the comparison circuit 409 compares the cell counter value Ca stored at the designated address (= VCI) of the cell counter 407 with the cell number prescribed value C stored in the cell number prescribed value table 408. In this case, Ca
= C = 1, the maximum / average speed monitoring unit 306 in FIG.
Does not output the violation determination output.

Thus, the reference time data t shown in FIG.
The cell arriving at the timing of n1 and temporarily held in the delay buffer 304 of FIG. 3 is output as a valid cell from the marking / cell forcible discard unit 305 to the subsequent ATM switch as it is.

On the other hand, when the subtraction circuit 403 and the comparison circuit 405 operate at the cell arrival timing of the reference time data tn2 in FIG. 6, the comparison result of the comparison circuit 405 becomes Tn2 <T. In this case, the cell counter value Ca of the designated address (= VCI) of the cell counter 407 is incremented by 1, and Ca =
It becomes 2. As a result, the comparison result of the comparison circuit 409 becomes C
a> C, and the violation determination output is output to the marking / cell forced discarding unit 305 in FIG. Here, as described above, when the determination result of the comparison circuit 405 is Tn2 <T,
The designated address (= VCI) of the time storage table 401 is not updated, and the time data tB2 remains stored at the same address.

As described above, the reference time data t shown in FIG.
The cells arriving at the timing of n2 and temporarily held in the delay buffer 304 of FIG.
In step 5, a specific mark is given as a violation cell, and the cell is output to the subsequent ATM switch. Alternatively, the marking / cell forcible discard unit 305 forcibly discards the cell as a violation cell and does not output it to the subsequent ATM switch.

The above-described violation processing operation is similarly performed at the cell arrival timing of the reference time data tn3 in FIG.
Thereafter, when the cell arrives at the reference time data tn4 in FIG. 6, the comparison result of the comparison circuit 405 becomes Tn4> T. This determination result is the same as that at the timing of tn1. Accordingly, the AND circuit 406 is turned on, and the reference time data tn4 of the reference counter 402 at that time is newly stored as time data tB3 at the designated address (= VCI) of the time storage table 401 again. At the same time, the cell counter value Ca at the specified address (= VCI) of the cell counter 407 is reset to "1". Then, the comparison circuit 409 calculates the cell counter value Ca stored at the designated address (= VCI) of the cell counter 407 and the cell number prescribed value C stored in the cell number prescribed value table 408.
Compare with In this case, since Ca = C = 1, the maximum / average speed monitoring unit 306 in FIG. 4 does not output a violation determination output.

Thus, the reference time data t shown in FIG.
The cell arriving at the timing of n4 is regarded as a valid cell,
The data is directly output from the mark assignment / cell forced discard unit 305 to the subsequent ATM switch via the delay buffer 304 in FIG.

The above description is for the case where the maximum / average speed monitoring unit 306 in FIG. 3 monitors the maximum speed. However, the maximum / average speed monitoring unit 306 in FIG. 3 can also perform the average speed monitoring. In this case, the user declares the average speed instead of the maximum speed at the time of calling. Then, in the cell number specified value table 408, as the cell number specified value C,
Instead of C = 1, an appropriate value (for example, 10000) is stored. In the cell arrival interval specified value table 404, as the cell arrival interval specified value T, not the one cell arrival interval but the cell number specified value C = 10000 calculated based on the reported value of the average speed from the user. The average interval at which the specified number of cells arrive is stored. in this case,
If it is not necessary to change the cell count value C for each call type and a fixed value is acceptable, the cell count value table 40 in FIG.
8 is not required, and the comparator circuit 409 only needs to input a fixed value C of the number of cells.

The above description of the operation does not refer to the processing when the reference time data tn of the reference counter 402 in FIG. 4 overflows. That is, when the reference time data tn of the reference counter 402 overflows, the reference time data tn is counted up from “0” again.
May be smaller than the time data tB stored in the data. In such a case, generally, the correct cell arrival interval Tn can be obtained by subtracting the time data tB from the maximum value of the reference time data tn and adding the current reference time data tn thereto. Therefore, such a control function may be provided in the subtraction circuit 403 of FIG. However, when the reference counter 402 overflows many times from the arrival of the previous cell to the arrival of the next cell, Tn = tn-tB even though the next cell is not a violating cell. Becomes smaller than the cell arrival interval prescribed value T, and a malfunction may be caused to be determined as a violating cell. A control process in which a violation cell is not determined in such a case will be described below.

First, in addition to the above-described time data tB, flag data such as an overflow display flag C1 and an overflow detection flag C2 as shown in FIG. 7 are stored in the address corresponding to each VCI in the time storage table 401 in FIG. Is stored. Then, the following control operation is performed.

That is, the time from when a cell arrives until it is output after being held in the delay buffer 304 in FIG. 3 is called one cell hold time. And first,
As shown in FIG. 8, in the time storage cycle which is the first half cycle within each one cell hold time, the time storage table 401
Time data t from the designated address (= VCI)
4 is performed, and as described above, the speed monitoring operation by the entire circuit of FIG. 4 is performed, and the writing operation of the reference time data tn to the time storage table 401 by the AND circuit 406 of FIG. 4 is performed. Is done. Along with such an operation of the hardware, a reference counter overflow determination operation based on an operation flowchart of FIG. 10 described later is executed by an overflow determination circuit process (not shown).

On the other hand, in the overflow detection cycle, which is the second half cycle within each one-cell hold time, an overflow control operation for the cell counter 407 as described below is executed. First, the reference counter 402 in FIG.
The count number until the reference time data tn overflows is equal to or greater than the number of VCIs to be monitored. Hereinafter, this is referred to as a reference counter overflow period. Then, for each cell hold time, the above-described overflow determination circuit executes a reference counter overflow determination operation based on an operation flowchart of FIG. 9 described later. This operation is for sequentially checking and controlling the contents of C1 and C2 of the address corresponding to each VCI of the cell counter 407 in FIG.
The addresses C1 and C2 corresponding to the CI are checked. The reference counter overflow determination operation in the overflow detection cycle shown in the operation flowchart of FIG. 9 will be described below.

First, the overflow display flag C1 and the overflow detection flag C2 of the address corresponding to the cell suspension time in the time storage table 401 of FIG. 4 are read for each overflow detection period of each cell suspension time.

Then, first, it is determined whether or not the overflow display flag C1 is "1" (S in FIG. 9).
1). If C1 is "1", no processing is performed, and the reference counter overflow determination operation in the overflow detection cycle ends (NO in S1 of FIG. 9).

If C1 is not "1", it is determined whether or not the overflow detection flag C2 is "1" (S2 in FIG. 9). If C2 is not "1", it is set to "1" and, together with C1, at the second half of the current overflow detection cycle (see FIG. 8), it corresponds to the current cell hold time of the time storage table 401. It is written to the address (S3 in FIG. 9). Now, C2 of the address corresponding to each VCI stored in the time storage table 401 is set to "0" when a cell having the VCI corresponding to the address comes in the processing in the time storage cycle of FIG. (S7, S7 in FIG. 10)
9). Therefore, as described above, C1 is not "1" but C1.
The state where 2 is not "1" is a case where at least one cell has come since the address was accessed in the previous reference counter overflow cycle. In such a case, C2 is set to "1".

On the other hand, C1 is not "1" and C2 is "1".
, C1 is set to “1” and C1 is set to “1”.
9 is written to the address of the time storage table 401 corresponding to the current cell suspension time at the second half of the current overflow detection cycle (see FIG. 8) (FIG. 9).
S4). This state occurs after C2 is set to "1" in the immediately preceding reference counter overflow cycle.
This is a state in which no cell has come. In such a case, C1 is set to "1", assuming that a sufficient time (one overflow cycle) has elapsed since the previous check.

In contrast to the processing operation based on FIG. 9 in the above-described overflow detection period, in the time storage period, the following processing operation based on the operation flowchart in FIG. Is executed.

First, when a cell arrives during the time storage period of each cell hold time, as described above, the VCI of the cell is detected via the circuits 301, 302, and 303 in FIG. The address of the time storage table 401 in FIG. 4 is specified. As a result, the overflow display flag C1 and the overflow detection flag C2 are read from the address.

First, it is determined whether or not the overflow display flag C1 is "1" (S10 in FIG. 10).
5). If C1 is not "1", then it is determined whether or not the overflow detection flag C2 is "1" (S6 in FIG. 10).

If C2 is not "1", no processing is performed, and the reference counter overflow determination operation in the time storage cycle ends (NO in S6 of FIG. 10). When C2 is "1", it is reset to "0" as described above (S7 in FIG. 10).

On the other hand, when C1 is "1", as described above, since a sufficient time (time for one overflow cycle) has elapsed since the previous check, the cell that has arrived this time is not a violating cell. . Therefore, in this case, an overflow process is performed (S8 in FIG. 10). That is, FIG.
Is output by the gate circuit (not shown) even if the comparison circuit 409 of FIG.
Output to the mark assignment / cell forced discard unit 305 is blocked.

Thereafter, the overflow display flag C1 and the overflow detection flag C2 of the designated address (= VCI) in the time storage table 401 in FIG. 4 are reset to "0" (S9 in FIG. 10).

As described above, it is possible to cope with the case where the reference time data tn of the reference counter 402 overflows. As can be seen from the above description of operation, in the present embodiment, the cell counter value Ca of the cell counter 407 is not reset at once for each cycle T calculated from the user's declared value, , The time interval from the last valid cell arrival is calculated, and if the interval is equal to or longer than the period T, only one cell counter value Ca corresponding to the call is reset. . 9 and 10 in addition to the hardware operation of FIG.
8, the cell counter 407 is accessed only four times within one cell hold time, including the read operation and the write operation. Since the number of accesses does not depend on the number of calls to be multiplexed, the number of calls that can be multiplexed is not limited as long as the memory capacity of the table permits. Therefore, not only the STM-1 line but also the STM-4 line with one cell hold time of 680 ns can be processed with sufficient margin. Further, unlike the second conventional example described above, there is an advantage that the value of the monitoring period T set based on the user's declared value is not limited, and it is not necessary to manage the closed state of the cell counter.

Next, the burst duration monitoring unit 30 shown in FIG.
The operation when the monitoring of the burst duration is performed in FIG. 7 will be described. In this case, the user declares the burst duration at the time of calling. In the address corresponding to the user's VCI in the burst duration prescribed value table 504 in FIG. 5, the burst duration based on the user's declaration is written by software processing of an ATM call control processor (not shown). Duration specified value T
Stored as B.

Thereafter, in the actual communication phase, the burst duration monitoring operation is performed by the burst duration monitoring section 307 of FIG. That is, first, since the burst duration is the duration of the maximum speed, FIG.
The output of the maximum / average speed monitoring unit 306 (FIG. 4) is used. However, in this case, it is assumed that the monitoring unit 306 is monitoring the maximum speed. When a cell arrives, first, the VCI of the cell is indicated by reference numerals 301 and 302 in FIG.
, And 303, and the addresses of the time storage table 501 and the burst duration prescribed value table 504 of FIG.

At this time, when the comparison result of the comparison circuit 405 in FIG. 4 is Tn> T, that is, when the cell does not arrive at the maximum speed, the AND circuit 506 is turned on, and the reference counter 502 at that time turns on. The time data tnB is newly stored again as the time data tBB at the designated address (= VCI) of the time storage table 501. Conversely, while the cell is arriving at the maximum speed, the time storage table 5
The time data tBB of 01 is not updated.

The subtraction circuit 503 in FIG. 5 calculates the reference time data tnB of the reference counter 502 when the cell arrives from
The burst duration time TnB is obtained by subtracting the time data tBB immediately before the maximum speed is stored at the designated address (= VCI) in the time storage table 501.
(Actual value) is calculated.

Subsequently, when the above-mentioned cell arrives, the comparison circuit 505 sends the burst duration TnB (actually measured value) and the designated address (==) in the burst duration prescribed value table 504.
VCI) is compared with a specified burst duration value TB (calculated value) to determine whether or not TnB> TB.
If nB> TB, a violation determination output is output to the mark assignment / cell forced discard unit 305 in FIG. That is, while the cell arrives at a speed that does not reach the maximum speed, the reference time data tnB of the reference counter 502 and the time storage table 50 are stored.
Since the time data tBB of 1 always coincides and the burst duration time TnB is always "0", the comparison circuit 505 does not output a violation determination output. On the other hand, while the cell is arriving at the maximum speed, its duration is the burst duration T
nB is observed, and when this exceeds the burst duration specified value TB, a violation determination output is output. When the cell arrives at a speed higher than the maximum speed, the maximum / average speed monitoring unit 306 in FIG.
Then, a violation determination output is output to the mark assignment / cell forced discard unit 305.

In this way, the delay buffer 30 shown in FIG.
The cell that violates the declared value of the burst duration temporarily held in No. 4 is marked with a specific mark as a violating cell by the mark adding / cell forcible discarding unit 305, and a subsequent A
Output to TM switch. Alternatively, the marking / cell forcible discard unit 305 forcibly discards the cell as a violation cell and does not output it to the subsequent ATM switch.

In the above description of the operation of the burst duration monitoring unit 307, as in the case of FIG.
Although the processing when the reference time data tnB of No. 02 overflows is not mentioned, it can be dealt with by the same processing as in the case of FIGS.

[0074]

According to the present invention, the cell counter value of the cell counter means is determined by the period T calculated from the declared value of the user.
Rather than resetting a plurality of calls collectively each time, each time a cell arrives, only one cell counter value corresponding to the call is reset based on the comparison result by the first comparing means. . That is, the number of accesses to the memory within one cell hold time does not depend on the number of calls to be multiplex-processed, and there is no limit to the number of calls that can be multiplex-processed as long as the memory capacity permits. Therefore, not only the STM-1 line but also the STM-4 line with one cell hold time of 680 ns can be processed with sufficient margin.

Unlike the second conventional example, there is no limitation on the value of the monitoring cycle T set based on the user's declared value, and there is no need to manage the closed state of the cell counter. Have. Further, similarly, it is possible to monitor the burst duration with a sufficient margin.

By using these cell monitoring devices, it is possible to realize a cell flow control device capable of appropriately performing cell flow control such as cell discarding or marking.

[Brief description of the drawings]

FIG. 1 is a block diagram (No. 1) of the present invention.

FIG. 2 is a block diagram (No. 2) of the present invention.

FIG. 3 is a basic configuration diagram of an embodiment of the present invention.

FIG. 4 is a configuration diagram of a maximum / average speed monitoring unit.

FIG. 5 is a configuration diagram of a burst duration monitoring unit.

FIG. 6 is an operation timing chart of the embodiment of the present invention.

FIG. 7 is a configuration diagram of a time storage table.

FIG. 8 is a timing chart of an access operation of the time storage table.

FIG. 9 is a flowchart (part 1) of a reference counter overflow determination operation.

FIG. 10 is a flowchart (part 2) of a reference counter overflow determination operation.

FIG. 11 is an operation explanatory view (part 1) of the first conventional example.

FIG. 12 is a diagram (part 2) illustrating the operation of the first conventional example.

FIG. 13 is a diagram (part 1) illustrating the operation of the second conventional example.

FIG. 14 is an operation explanatory diagram (part 2) of the second conventional example.

[Explanation of symbols]

 Reference Signs List 101 Reference time data generation means 102 Gate signal 103 Time data storage means 104 Subtraction means 105 Cell arrival interval prescribed value storage means 106 First comparison means 107 Cell counter means 108 Cell number prescribed value storage means 109 Second comparison means 110 2 time data storage means 111 second subtraction means 112 burst duration specified value storage means 113 third comparison means

Claims (6)

(57) [Claims] 1. A cell monitoring apparatus for monitoring a maximum cell speed on a subscriber interface of an ATM switching system, comprising: reference time data generating means for generating reference time data; and time data corresponding to each call. Time data storage means for rewriting time data corresponding to the call of the arriving cell with reference time data generated from the reference time data generation means when a gate signal is input at the arrival time of the cell; At the timing, by subtracting the time data corresponding to the call of the arriving cell stored in the time data storage means from the reference time data generated by the reference time data generation means, 1 cell arrival interval, which is the time interval from the arrival time of the previous non-violating cell corresponding to Subtraction means for measuring, and one-cell arrival interval prescribed value storage means for storing a one-cell arrival interval prescribed value corresponding to each call calculated based on the maximum speed of a cell declared by a user at the time of setting up each call And a cell arrival timing corresponding to the one cell arrival interval corresponding to the call of the arrival cell measured by the subtraction means and the call of the arrival cell stored in the one cell arrival interval prescribed value storage means. First comparing means for comparing the one-cell arrival interval specified value with the specified value and outputting the gate signal when the one-cell arrival interval is equal to or greater than the one-cell arrival interval specified value; and a cell counter value corresponding to each call. And at the cell arrival timing, the cell counter value corresponding to the call of the arriving cell is equal to or greater than the one cell arrival interval stipulated value in the first comparing means. The cell counter is reset when it is determined, and is incremented by 1 when it is determined that the one-cell arrival interval is smaller than the one-cell arrival interval prescribed value, and stored in the cell counter with the cell arrival timing. Comparing whether the cell counter value corresponding to the call of the arrival cell is greater than 1, and if the cell counter value exceeds 1, it is determined that the arrival cell is a cell violating the declaration of the maximum speed. And a second comparing means. 2. A cell monitoring apparatus for monitoring an average cell speed on a subscriber interface of an ATM switching system, comprising: reference time data generating means (101) for generating reference time data (tn); Time data (t
B) and store the gate signal (1) at the cell arrival timing.
02), the time data (tB) corresponding to the call of the arriving cell is rewritten by the reference time data (tn) generated by the reference time data generation means (101). 103), and the reference time data generating means (10
By subtracting the time data (tB) corresponding to the arriving cell call stored in the time data storage means (103) from the reference time data (tn) generated from 1), the time data is obtained. A subtraction means (104) for measuring a cell arrival interval (Tn) which is a time interval from a time point at which the previous time data corresponding to the call of the arrival cell is rewritten in the storage means (103) to a time point at which the current cell arrives; ,
A cell arrival interval specified value storage means (105) for storing a cell arrival interval specified value (T) corresponding to each call calculated based on an average cell speed declared by a user at the time of setting each call; At the cell arrival timing, the cell arrival interval (Tn) corresponding to the call of the arrival cell measured by the subtraction means (104) and the arrival cell stored in the cell arrival interval prescribed value storage means (105) And comparing the specified cell arrival interval (T) with the specified cell arrival interval (Tn) and outputting the gate signal (102) when the cell arrival interval (Tn) is equal to or longer than the specified cell arrival interval (T). 1
And the cell counter value (Ca) corresponding to each call is stored.
Cell counter value (Ca) corresponding to the call of the arriving cell
Is reset when the first comparison means (106) determines that the cell arrival interval (Tn) is equal to or greater than the cell arrival interval specified value (T), and the cell arrival interval (Tn) is reset. The cell counter means (107) which is incremented by 1 when it is determined that the cell arrival interval is smaller than the prescribed value (T), and the cell counter means (107) calculated based on the average cell speed declared by the user at the time of setting each call. A cell number specified value storage means (108) for storing a cell number specified value (C) corresponding to each call; and a cell arrival time stored in the cell counter means (107) at a cell arrival timing. A comparison is made as to whether the corresponding cell counter value (Ca) exceeds the cell number prescribed value (C) corresponding to the call of the arrival cell stored in the cell number prescribed value storage means (108). If The arriving cell is cell monitoring apparatus characterized by having a second comparison means (109) determines that a cell violating declaration of the average speed. 3. A cell monitoring device for monitoring an average rate of cells on a subscriber interface of an ATM switching system, comprising: reference time data generating means for generating reference time data; and time data corresponding to each call. Time data storage means for rewriting time data corresponding to the call of the arriving cell with reference time data generated from the reference time data generation means when a gate signal is input at the arrival time of the cell; By subtracting the time data corresponding to the call of the arriving cell stored in the time data storage means from the reference time data generated by the reference time data generation means at the timing, the time data storage means From the time of rewriting of the previous time data corresponding to the call of the arriving cell to the time of arrival of the current cell Subtraction means for measuring a cell arrival interval as an interval, and a cell for storing a cell arrival interval prescribed value corresponding to each call calculated based on an average speed of a cell declared by a user at the time of setting each call. An arrival interval specified value storage means, a cell arrival timing corresponding to the call of the arrival cell measured by the subtraction means at the cell arrival timing, and a cell arrival interval stored in the cell arrival interval specified value storage means. First comparing means for comparing a cell arrival interval specified value corresponding to a call and outputting the gate signal when the cell arrival interval is equal to or longer than the cell arrival interval specified value; and a cell counter corresponding to each call. A cell counter value corresponding to the call of the arriving cell when the cell arrival interval is equal to or less than the cell arrival interval specified value in the first comparing means. The cell counter is reset when it is determined that the cell arrival interval is smaller than the cell arrival interval specified value, and is incremented by 1 when the cell arrival interval is smaller than the cell arrival interval specified value. A comparison is made as to whether the stored cell counter value corresponding to the call of the arriving cell exceeds a prescribed number of cells, and if so, the arriving cell violates the average speed declaration. And a second comparing means for determining that the cell is a cell. 4. A cell monitoring device for monitoring an average cell speed on a subscriber interface of an ATM switching system, wherein reference time data generating means for generating reference time data, and time data corresponding to each call are stored. Time data storage means for rewriting time data corresponding to the call of the arriving cell with reference time data generated from the reference time data generation means when a gate signal is input at the arrival time of the cell; By subtracting the time data corresponding to the call of the arriving cell stored in the time data storage means from the reference time data generated by the reference time data generation means at the timing, the time data storage means From the time of rewriting of the previous time data corresponding to the call of the arriving cell to the time of arrival of the current cell Subtracting means for measuring a cell arrival interval, which is an interval, and comparing the cell arrival interval corresponding to the call of the arrival cell measured by the subtraction means with a predetermined cell arrival interval prescribed value at the cell arrival timing. A first comparing means for outputting the gate signal when the cell arrival interval is equal to or greater than the predetermined cell arrival interval prescribed value, and a cell counter value corresponding to each call are stored. The cell counter value corresponding to the call of the arriving cell is reset when the first comparison means determines that the cell arrival interval is equal to or greater than the predetermined cell arrival interval specified value, and the cell arrival interval is reset. Cell counter means which is incremented by 1 when it is determined that is smaller than the predetermined cell arrival interval prescribed value, and the average rate of cells declared by the user at the time of setting up each call A cell number specified value storage means for storing a cell number specified value corresponding to each call calculated based on the call; and a cell corresponding to the call of the arrival cell stored in the cell counter means at a cell arrival timing. A comparison is made as to whether or not the counter value exceeds a cell number prescribed value corresponding to the call of the arrival cell stored in the cell number prescribed value storage means. And a second comparing unit that determines that the cell violates the declaration of the above. 5. A cell monitoring apparatus for monitoring a maximum rate of a cell and a burst duration, which is a time during which the cell continuously enters at the maximum rate, on a subscriber interface of an ATM switching system. The second time data (tB) to be stored is stored, and when the one cell arrival interval is determined to be larger than the one cell arrival interval prescribed value by the first comparing means at the cell arrival timing, the cell has arrived. Second time data storage means (110) in which second time data (tB) corresponding to a cell call is rewritten with reference time data (tnB) generated by the reference time data generation means; And the reference time data (tn) generated by the reference time data generation means.
By subtracting the second time data (tB) corresponding to the call of the arriving cell stored in the second time data storage means (110) from B), the call of the arriving cell can be handled. Second subtraction means (111) for measuring a burst duration (TnB) to be performed, and a burst duration corresponding to each call calculated based on a burst duration of a cell declared by a user at the time of setting up each call. Time specified value (T
B) and a burst duration specified value storage means (11).
2) and at the arrival timing of the cell, the burst duration (TnB) corresponding to the call of the arrival cell measured by the second subtraction means (111) is stored in the burst duration prescribed value storage means (112). A comparison is made as to whether the stored burst duration value (TB) corresponding to the call of the arrival cell is exceeded, and if so, the arrival cell violates the burst duration declaration. 3. The cell monitoring device according to claim 1, further comprising: third comparing means (113) for determining that 6. A cell flow rate control means for controlling a flow rate of an arriving cell based on a result of monitoring by the cell monitoring apparatus according to claim 1, 2, 3, 4, or 5. Control device.