JP2895657B2 - Monitoring system for ATM transmission network - 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 an ATM transmission network, and more particularly to a method for measuring the policing of an ATM cell at each node of the ATM transmission network.

[0002] As a technology for realizing a high-speed and broadband integrated network (B-ISDN) aiming at a wide range of multimedia services, research on an ATM (Asynchronous Transfer Mode) transmission network has been actively conducted recently.

In this ATM transmission network, as shown in FIG. 7 (b), a voice terminal such as a telephone, a visual terminal such as a television terminal, a facsimile, a transmission terminal between computers and the like are connected to the subscriber side. As shown in the example of NNI (between transmission networks) in FIG.
8 bytes), and all the information is unified in the cell (packet) format composed of a number of nodes, that is, the path between the cross-connect devices of the ATM transmission network is asynchronously transmitted. The STM (Synchronous Transcription) can be used because transmission efficiency increases the use efficiency of the line, and can handle all speeds from low speed to high speed.
(sfer Mode: Synchronous transfer technology) Compared to a transmission network, time slot allocation processing is less troublesome, so that it is suitable for distributed processing control and multiplex transmission with high flexibility is possible.

When such an ATM transmission network is used for a subscriber system, if the transmission of free cells is allowed to the subscribers, unfairness occurs between the subscribers due to a difference in frequency of information generation.
The upper limit of the cells that can be transmitted per unit time is previously contracted between the subscriber of the transmission network (network) existing at each node and the subscriber, and the subscriber transmits the cells in accordance with the contract, and transmits the cell according to the contract. Requires a policing function to check at the entrance of the transmission network whether the subscriber is sending out cells in an amount within the range of the contract and protect the own network.

[0005]

2. Description of the Related Art In order to realize the above-mentioned policing function, it is necessary to measure the flow rate of a cell for each channel, and this channel is used for one transmission between a subscriber and a node. A plurality of logical channels separated on the road, such as VPI (Virtual Path Identifier) and VCI (Vir
Tual Channel Identifier) is used for identification.

Various methods have been proposed for performing such cell measurement. However, as shown in FIG. 8 (a), the method for measuring the cell arrival time interval T is the most reliable value. It is reported that it can be obtained.

Now, if the previous cell arrives at time to, and the cell arrives at time t, the cell arrival time interval T becomes T = t-to, and the peak value Vp of the cell flow rate becomes Vp = It can be calculated as 1 / T.

FIG. 9 shows an example of a conventional circuit configuration for measuring the cell arrival time interval based on such cell arrival. A counter (register) 11 for storing the time of the cell currently arriving is provided with a counter (register) 11. , The arrival time of the previous cell is stored, and the arrival time interval T is calculated by the previous cell arrival time A from the register 12 and the current time B from the counter 11.
The calculation unit 13 calculates B-A, and calculates the cell flow rate based on the time interval T obtained in this manner.

[0009]

SUMMARY OF THE INVENTION Such a conventional AT
In the method of monitoring the cell flow rate of the M transmission network, the register for storing the current time and the previous cell arrival time is stored in the existing V.
Since it is necessary to prepare registers of the number of stages corresponding to the number of PIs or VCIs, the number of circuits increases.

Further, since the number of stages of such a register is finite, if the arrival time interval becomes longer than the maximum measurable interval Tmax determined by the number of stages of the register as shown in FIG. 8B, the circuit of FIG. In addition, there is a problem in that the time interval of arrival time interval T−Tmax = T ′ is measured, and erroneous determination of the cell flow rate occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM transmission network monitoring system capable of accurately measuring a cell flow rate without increasing the circuit scale.

[0012]

FIG. 1 is a block diagram of an embodiment of the present invention.
In the present invention, an input / output unit 1 for setting an initial value and outputting a measurement result, and a timer 2 for generating a time are shown.
And a memory 3 for measuring work and storing the result, and detecting a cell arriving for the first time after the start of the measurement.
And a traffic measuring unit 4 which writes the time from the memory 3 to the memory 3 for each identifier and, when a predetermined measurement allowable time elapses until the next cell having the same identifier arrives, determines that the measurement is abnormal and restarts the measurement. I have.

Further, in the present invention, the initial value includes the lower limit value of the time interval of the arriving cell,
Stores the number of violations in the memory 3 as a violation when the arrival time interval between two cells having the same identifier after the start of the measurement is equal to or less than the lower limit value. An identifier can be output from the input / output unit 1.

Further, according to the present invention, the traffic measuring unit 4
However, the minimum value of the arriving time interval along with the number of violations may be stored in the memory 3, and the minimum arrival time interval may be output from the input / output unit 1 at the end of the measurement.

Further, in the present invention, the memory 3 is stored in the first memory.
And a second memory 5 for an overflow check operation in which an address management value for each cell identifier in the first memory 3 is stored when the first memory 3 is used. It is also possible to repeat the measurement when a predetermined time elapses from the time of the cell arriving for the first time after the start of measurement for each identifier in the first memory 3 according to the address managed in the first memory 3 until the next cell arrives. It is.

[0016]

In the present invention shown in FIG. 1, in the input / output unit 1, the initial value of the entire apparatus including the lower limit value of the time interval of the arrival cell is set.
The cell arriving for the first time after the start of the measurement is detected, and the time detected by the timer 2 is stored in the memory 3.
To save. However, at this time, the traffic measuring unit 4 stores the time for each cell identifier.

When the traffic measuring unit 4 detects that the next cell with the same identifier has arrived, the arrival time interval between the detected time and the time of the previous cell stored in the memory 3 is set to the lower limit. If the value is not less than the value, the measurement is continued as it is normal, and no special signal is generated.

On the other hand, when the cell having the same identifier has not arrived since the previous cell arrived and the predetermined measurement allowable time has elapsed, the arrival of the cell is abnormal. Since the measurement is not reliable, the measurement is repeated and the output from the input / output unit 1 is prevented.

Thus, even if the number of identifiers increases, only the capacity of the memory 3 needs to be increased, which has almost no effect on the circuit scale. In addition, when the cell arrival time interval becomes abnormally long. To avoid giving incorrect measurement results.

Conversely, the traffic measuring unit 4 of the present invention
When the arrival time interval between two cells having the same identifier after the start of measurement is equal to or smaller than the lower limit, the number of violations is stored in the memory 3 during the measurement period because the arrival of the cell violates too early. The number of violations and the identifier thereof can be output from the input / output unit 1 at the end of the measurement.

Further, in the present invention, the traffic measuring unit 4
However, the minimum value of the arrival time interval is stored in the memory 3 together with the number of violations, and the minimum arrival time interval is also output from the input / output unit 1 at the end of the measurement, thereby notifying the time interval of the violated cell. It becomes possible.

[0022]

FIG. 1 shows an ATM according to the present invention as described above.
Not only are the principle configuration blocks of each node in the transmission network monitoring system shown, but also the contents of first and second memories 3 and 5 used in the embodiment described below. , VPI or VC as identifier
I, the arrival time to of the previous cell, the peak value tp of the cell arrival time, the lower limit value Tlim of the arrival time interval, the number of violations n, and the measurement start flag F as the parameters of the cell identified by each identifier. And save it. In the memory 5, an overflow check count value nc and a limit value Nc of the nc value are set.
And an address management value (initial value) Ac using the identifiers 0 to m of the memory 3 as addresses.

FIG. 2 shows an outline of the policing algorithm of the monitoring system of the ATM transmission network according to the present invention. As shown in the drawing, a traffic measurement subroutine SUB1 by the traffic measurement unit 4 and a measurement result are shown. And a subroutine SUB2 for reading the subroutine. Specific examples of these subroutines SUB1 and SUB2 are shown in FIGS. 3 and 6, respectively, and subroutines SUB3 and SUB used in the subroutine in FIG.
4 are shown in FIGS. 4 and 5, respectively.

The operation of the embodiment of the present invention will be described below with reference to FIGS.

[0025]Traffic measurement algorithm (see Figure 3)
See) First, when the measurement is started, the initial setting shown in FIG.
Subroutine SUB3 is executed.

[0026]Initial setting algorithm (see Fig. 4)  That is, as shown in FIG.
First, the current time t is obtained from the timer 2 (step S2).
1), the above-mentioned parameters n and F are set to “0” for each identifier.
And Tlim is set to a predetermined lower limit,
p is set to, for example, "0" (step S22).

After the initialization has been completed in this way, returning to FIG. 3, it is next determined whether or not the measurement has been completed (step S1). This ends when a measurement end command is received from the control unit (not shown), and otherwise, the measurement process is continued.

Next, it is determined whether or not a cell has arrived (step S2). This is set so that the ATM transmission network always receives either a cell real cell or an empty cell. Therefore, it is determined whether or not the cell input when executing step S2 is a real cell.

When the arrival of a cell (hereinafter, referred to as a real cell) is detected, for example, a VPI number as an identifier of the cell is extracted (step S3), and the cell arrival time t at this time is detected (step S3). At the same time as step S4), it is determined whether or not this cell has arrived for the first time.
(Step S5). In this case, since F = 0 at the beginning, the flag F is set to "1" in step S6, and the time t is set to the arrival time to of the previous cell in step S13, and the corresponding VPI number in the memory 3 is set. And returns to step S1.

On the other hand, when the cell is not the first cell, the arrival time to of the previous cell is read from the memory 3 (step S7), and the arrival time interval T = t-to is calculated (step S8).

The arrival time interval T thus obtained is
It is determined whether or not a violation has occurred below the lower limit value Tlim (step S9). If no violation has occurred, the process returns to step S1 via step S13.
When it is determined that the violation has occurred as Tlim, the number of violations n (which is initially "0") in the memory 3 is incremented by "1" (step S10). Values Tp and T of the arrival time interval during
It is determined whether or not the relationship is <Tp, that is, whether or not the value is below the peak value (step S11). As a result, when it is determined that the relationship is T <Tp, the process returns to step S1. Otherwise, the peak value of the smaller arrival time interval (larger cell flow rate) is stored in the memory 3 (step S12), and is updated when a smaller peak value occurs later.

On the other hand, if it is determined in step S2 that no cell has arrived, nc of the memory 5 is read (step S14), and whether or not this nc has exceeded the limit value Nc also set in the memory 5 is determined. Is determined (step S15). Note that this Nc is for executing the following overflow check subroutine SUB4 once every several times without always executing it. For example, "3"
If it has a value, the subroutine SUB4 is executed only once every three times.

As a result, when Nc <nc is not satisfied, n
c is incremented (step S16), and the memory 6
Is updated, the subroutine SUB4 is executed when Nc <nc, and then nc is reset (nc = nc).
0) (Step S17), and return to Step S1.

[0034]Overflow check algorithm (see Fig. 5)  Overflow check subroutine SUB4
The algorithm is shown in FIG.
It is executed at a cycle independent of the processing of the measuring unit 4.
First, the address management value Ac is read from the memory 5.
(Step S31) and a measurement start flag from the memory 3
F is read (step S32).

Then, it is determined whether or not the measurement start flag F is "1", that is, whether only the first cell after the start of measurement or the next cell is currently detected. (Step S33) When F = 1, it is not the state of the first cell, so the process proceeds to Step S39, where Ac is incremented, and Ac and F of the next address (VPI number) of the memory 3 are read.

However, if it is determined in step S33 that the flag F = 1, the current cell is in the first cell state, so that the current time t is obtained from the timer 2 (step S34) and the time before the specified VPI number is reached. The cell arrival time to is read from the memory 3 (step S35), and an arrival time interval T = t-to is calculated (step S3).
6).

The most significant bit (MSB) of the calculated arrival time interval T represented by the data bit is "1".
It is determined whether or not it is (step S37). If it is not "1", the process proceeds to step S39, but if not, the measurement start flag F is reset to "0" (step S38). The subroutine SUB4 ends when all the addresses Ac have been designated, and proceeds to step S17 in FIG.

Here, the meaning of judging whether or not the most significant bit of the arrival time interval T is "1" means half the maximum time indicated by the arrival time to of the memory 3 when the first cell arrives. Is determined. This is because the VPI number of the memory 3 is from 0 to m, so that the step S37 is determined based on the maximum allowable arrival time interval represented as the arrival time to, the arrival time interval T of a certain VPI number is checked. This is because the arrival time interval T of another VPI number exceeds the maximum permissible time interval during the operation. Therefore, the most significant bit at this time corresponds to a predetermined measurement allowable time.

[0039]Result read processing algorithm (see Fig. 6)  The subroutine SUB2 of the result reading process shown in FIG.
As shown in FIG. 6, the input / output unit 1
A read address is set (step S41).
The number of violations n of the VPI number corresponding to the dress is read out.
(Step S42), it is determined whether or not this n is “0”
Is performed (step S43).

In this case, if n = 0, no violation has occurred, so the flow advances to step S46 and further to step S4.
Returning to 1, it is determined whether or not n of the next address is "0".
If n = 0 is not satisfied, Vp at that address is read out (step S44) and notified to a control unit (not shown) (step S45). Thus, all V
The input / output unit 1 executes a reading process for the PI number.

In the above embodiment, the overflow check memory 5 is provided separately from the memory 3 for processing. However, the memory 5 also achieves the same function even when incorporated in the traffic measuring unit 4. be able to.

[0042]

As described above, according to the monitoring system of the ATM transmission network according to the present invention, each node stores the time of the cell arriving for the first time after the start of measurement in the memory, and from this time, the next time of the same identifier. When a predetermined measurement allowable time elapses before the cell arrives, it is determined that the measurement is abnormal, and the measurement is restarted. Therefore, the arrival time of the previous cell can be saved in the memory, and each VPI (VCI) can be stored. No need to provide any registers, the circuit scale can be reduced, and even when the cell arrives beyond the storage limit of the physical arrival time interval of the memory, an accurate cell flow can be obtained without giving an erroneous cell flow result. Can be given.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of each node and an embodiment of each memory of an ATM transmission network monitoring method according to the present invention.

FIG. 2 is a flowchart for explaining a policing algorithm used in a monitoring method of an ATM transmission network according to the present invention.

FIG. 3 is a flowchart for explaining an algorithm of a traffic measuring unit used in the monitoring method of the ATM transmission network according to the present invention.

FIG. 4 is a flowchart for explaining an initialization algorithm used in the ATM transmission network monitoring method according to the present invention.

FIG. 5 is a flowchart for explaining an algorithm of an overflow check used in a monitoring method of an ATM transmission network according to the present invention.

FIG. 6 is a flowchart for explaining an algorithm of a measurement result reading process used in the ATM transmission network monitoring method according to the present invention.

FIG. 7 is a diagram for explaining an ATM cell used in the present invention.

FIG. 8 is a diagram for explaining an arrival time interval of an ATM cell.

FIG. 9 is a diagram showing a conventional measurement circuit using a register.

[Explanation of symbols]

 Reference Signs List 1 input / output unit 2 timer 3 memory for measurement work and result storage 4 traffic measurement unit 5 memory for overflow check work

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-69232 (JP, A) JP-A-4-266240 (JP, A) JP-A-4-281644 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H04L 12/24-12/28 H04L 12/56

Claims (4)

(57) [Claims] An input / output unit (1) for setting an initial value and outputting a measurement result, a timer (2) for generating a time, a memory (3) for measuring work and storing the result, and after starting the measurement. The cell arriving for the first time is detected, the time from the timer (2) at that time is written into the memory (3) for each identifier, and a predetermined measurement allowable time has elapsed until the next cell with the same identifier arrives. And a traffic measuring unit (4) for re-measurement as occasional abnormality. 2. The method according to claim 1, wherein the initial value includes a lower limit value of a time interval of an arriving cell, and the traffic measuring unit (4) performs the operation after the start of the measurement.
When the arrival time interval between two cells having the same identifier is equal to or smaller than the lower limit, the number of violations is stored in the memory (3) as a violation, and the number of violations and the identifier are entered at the end of measurement. 2. The monitoring system for an ATM transmission network according to claim 1, wherein the output is outputted from an output unit (1). 3. The traffic measurement unit (4) stores the minimum value of the violation time interval together with the violation count in the memory.
3. The ATM transmission network monitoring system according to claim 2, wherein the minimum arrival time interval is output from the input / output unit (1) when the measurement is completed. 4. An overflow check second memory (5) storing an address management value for each cell identifier in the first memory (3) when the memory (3) is a first memory. ), And the traffic measurement unit (4)
Is a predetermined time from the time of the first cell arriving after the start of measurement for each identifier in the first memory (3) according to the address managed in the second memory (5) until the next cell arrives. 4. The monitoring method for an ATM transmission network according to claim 1, wherein the measurement is restarted when the time has elapsed.