JPH04329733A - Monitor system for transmission network - Google Patents

Abstract

PURPOSE:To realize the monitor of an ATM transmission network able to measure a cell flow without increasing the circuit scale by providing an input/ output section, a timer, a memory and a traffic measuring section to the system. CONSTITUTION:An initial value for the entire device is set to an input output section 1. A traffic measurement section 4 continues the measurement when a preceding cell arrival time and arrival time interval in the memory 3 are not a lower limit at the arrival of a succeeding cell of a same identifier. The measurement is a gain implemented when the measurement allowable time is exceeded and the result is not outputted from the input output section 1. Thus, even when number of identifiers is increased, the system copes with it by having only to increase the capacity of the memory 3, the circuit scale is not affected and no error measurement result is outputted. When the arrival time interval between cells of the same identifier is less than the lower limit, number of times of violation is accumulated to the memory 3, the number of times of violation and its identifier are outputted from the input output section 1 at the end of the measurement to inform the time interval of the violation cell. Thus, the cell flow is accurately given.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM transmission network monitoring system, and more particularly to an ATM cell policing measurement system at each node of an ATM transmission network.

[0002] Recently, ATM (Asynchronous Trans
(fer Mode: Asynchronous transfer technology) Research on transmission networks is being actively conducted.

As shown in FIG. 7(b), this ATM transmission network has voice terminals such as telephones, visual terminals such as television terminals, fax machines, computer transmission terminals, etc. connected to the subscriber side, as shown in FIG. 7(b). As shown in the example of NNI (transmission network) in Figure (a), all information is unified in a cell (packet) format consisting of a header part (5 bytes) and a payload part (48 bytes). It performs asynchronous transmission on paths between nodes, that is, cross-connect devices in an ATM transmission network, and transmits cells only when information is generated, increasing line usage efficiency and unifying all speeds from low to high speeds. STM (Syn
Chronous Transfer Mode (Synchronous Transfer Technology) Compared to a transmission network, time slot allocation processing is unnecessary, so it is suitable for distributed processing control and enables highly flexible multiplexed transmission.

[0004] When such an ATM transmission network is used for a subscriber system, if subscribers are allowed to send out cells freely, unfairness will arise between subscribers due to differences in the frequency of information generation.
The upper limit of cells that can be transmitted per unit time is contracted in advance between the supplier of the transmission network (network) existing at each node and the subscriber, and the subscriber transmits cells according to the contract, and the subscriber A policing function is required to protect the own network by checking at the entrance of the transmission network whether the subscriber is transmitting cells in an amount within the contracted range.

[0005]

[Prior Art] In order to realize the above-mentioned policing function, it is necessary to measure the cell flow rate for each channel, and this channel is a single transmission line between a subscriber and a node. A virtual path identifier (VPI)
ifier) and VCI (Virtual Channel)
It is identified by using an identifier called el Identifier.

[0006] Various methods have been proposed to measure cells in this way, but the method that measures the cell arrival time interval T, as shown in Fig. 8(a), provides the most reliable value. It has been reported that it can be obtained.

[0007] Now, the previous cell arrives at time to, and time t
If a cell arrives at , the cell arrival time interval T is
T=t-to, and the peak value Vp of cell flow rate can be calculated as Vp=1/T.

[0008] An example of a conventional circuit configuration for measuring the cell arrival time interval based on the arrival of cells is shown in FIG. , a register 12 that stores the arrival time of the previous cell, the arrival time A of the previous cell from the register 12, and the current time B from the counter 11, the arrival time interval T=
The cell flow rate is calculated based on the time interval T obtained in this way.

[0009]

[Problem to be solved by the invention] Such a conventional AT
In the method of monitoring the cell flow rate of the M transmission network, the registers that store the current time and the previous cell arrival time are
Since it is necessary to prepare a number of stages of registers corresponding to the number of PIs or VCIs, the number of circuits increases.

Furthermore, since the number of stages of such a register is finite, as shown in FIG. 8(b), when the arrival time interval becomes longer than the maximum measurable interval Tmax determined by the number of stages of the register, the circuit of FIG. , arrival time interval T-Tmax
There is a problem in that a time interval of =T' is measured, resulting in an erroneous determination of the cell flow rate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to realize an ATM transmission network monitoring system that can accurately measure cell flow rate without increasing the circuit scale.

0012

[Means for Solving the Problems] FIG. 1 shows A according to the present invention.
This diagram conceptually shows the configuration of each node in the monitoring system of a TM transmission network, and in the present invention, an input/output unit 1 that sets initial values and outputs measurement results, and a timer 2 that generates time.
, a memory 3 for measurement work and storage of results, and a timer 2 that detects the cell that arrives for the first time after the start of measurement.
and a traffic measurement unit 4 that writes the time from 1 to 3 in the memory 3 for each identifier, and when a predetermined measurement allowable time has elapsed until the next cell with the same identifier arrives, it is determined that there is an abnormality and the measurement is restarted. There is.

Further, in the present invention, the above initial value includes the lower limit value of the time interval of arriving cells, and the traffic measuring unit 4
When the arrival time interval between two cells with the same identifier after the start of measurement is less than or equal to the lower limit value, the violation is assumed to have occurred and the violation count is stored in the memory 3, and at the end of the measurement, the violation count and its value are stored. The input/output unit 1 can output the identifier.

Furthermore, in the present invention, the traffic measuring section 4
However, it is also possible to store the minimum value of the violation arrival time interval together with the violation count in the memory 3, and output the minimum arrival time interval from the input/output unit 1 when the measurement ends.

Furthermore, in the present invention, the memory 3 is
The traffic measuring section 4 further includes a second memory 5 for overflow checking that stores address management values for each cell identifier in the first memory 3. It is also possible to redo the measurement for each identifier in the first memory 3 according to the address managed in 5 when a predetermined time has elapsed from the time of the cell that first arrived after the start of measurement until the next cell arrives. It is.

[0016]

[Operation] In the present invention shown in FIG. 1, the input/output unit 1 sets initial values for the entire device including the lower limit value of the time interval of arriving cells, and then the traffic measurement unit 4
The first cell to arrive after the start of measurement is detected, and the time generated from timer 2 is stored in memory 3.
Save it to . However, at this time, the traffic measurement unit 4 stores the time for each cell identifier.

[0017] When the traffic measurement unit 4 detects the arrival of the next cell with the same identifier, the arrival time interval between the detection time and the time of the previous cell stored in the memory 3 falls within the above lower limit. If it is less than the value, it is normal, so the measurement continues and no special signal is generated.

On the other hand, if the next cell with the same identifier does not arrive after the previous cell arrives and the predetermined measurement allowable time has elapsed, the arrival of the cell is abnormal, so in this case the measurement result is Since it is not reliable, the measurement is redone and the input/output unit 1 is not output.

[0019] As a result, even if the number of identifiers increases, the capacity of the memory 3 only needs to be increased and the circuit scale is hardly affected. This is to avoid giving incorrect measurement results.

Conversely, the traffic measuring section 4 of the present invention
Then, if the arrival time interval between two cells with the same identifier after the start of measurement is less than or equal to the lower limit value, the cell arrived too early and there is a violation, so the number of violations is stored in the memory 3 during the measurement period. The number of violations and their identifiers can be outputted from the input/output unit 1 at the end of the measurement.

Furthermore, in the present invention, the traffic measuring section 4
However, by storing the minimum value of the arrival time interval together with the number of violations in the memory 3, and outputting the minimum arrival time interval from the input/output unit 1 at the end of the measurement, the time interval of the violating cell can be notified. It becomes possible.

[0022]

[Embodiment] FIG. 1 shows an ATM according to the present invention as described above.
In addition to showing the principle configuration blocks of each node in the transmission network monitoring system, the contents of the first and second memories 3 and 5 used in the embodiment described below are shown. , VPI or VC as an identifier
I, and the parameters of the cell identified by each identifier are 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 and is designed to be saved. In addition, in the memory 5, an overflow check count value nc and a limit value N of this nc value are stored.
c and an address management value (initial value) Ac whose addresses are identifiers 0 to m of the memory 3.

FIG. 2 shows an overview of the policing algorithm of the ATM transmission network monitoring system according to the present invention. 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.
Four specific examples 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. 3 to 6.

Traffic Measurement Algorithm (See FIG. 3) First, when measurement is started, the initial setting subroutine SUB3 shown in FIG. 4 is executed.

Initial setting algorithm (see FIG. 4) That is, as shown in FIG. 4, the traffic measurement unit 4 first obtains the current time t from the timer 2 (step S21).
, set the above-mentioned parameters n and F to "0" for each identifier, and set Tlim to a predetermined lower limit value,
For example, Tp is set to "0" (step S22
).

After the initial setting is completed in this way, the process returns to FIG. 3 and it is then determined whether the measurement is completed (step S1). This ends when a measurement end command is received from a control unit (not shown), and the measurement process continues otherwise.

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

When the arrival of a cell (hereinafter referred to as an actual cell) is detected, for example, the VPI number as an identifier of the cell is extracted (step S3), and the cell arrival time t at this time is detected ( At step S4), the measurement start flag F is used to check whether this cell is the first cell to arrive.
The determination is made according to (step S5). In this case, since F=0 if it is the first time, the flag F is set to "1" in step S6.
At the same time, in step S13, the above time t is set as the arrival time to of the previous cell, and the corresponding VP in the memory 3 is set to
It is saved in the I number to, and the process returns to step S1.

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

The arrival time interval T obtained in this way is
It is determined whether the above lower limit value Tlim or less has been violated (step S9), and if there is no violation, the process returns to step S1 via step S13.
<Tlim and it is found that there is a violation, the violation count n (initially “0”) in memory 3 is set to “1”.
” (step S10), and further determines whether or not this arrival time interval T is in the relationship T<Tp with the peak value Tp of arrival time intervals in the memory 3, that is, whether it is lower than the previous peak value. As a result, if it is found that T<Tp, the process returns to step S1, but if not, the peak value of the smaller arrival time interval (larger cell flow rate) is stored in the memory 3. (step S12), and will be updated when an even smaller peak value occurs later.

On the other hand, when it is found in step S2 that no cell has arrived, nc in the memory 5 is read out (step S14), and it is determined whether or not this nc exceeds the limit value Nc which is also set in the memory 5. (Step S15). Note that this Nc is for not always executing the following overflow check subroutine SUB4, but only once every few times, for example, "3".
If the subroutine SUB4 has a value such that the subroutine SUB4 is executed only once every three times.

As a result, when Nc<nc, n
Increment c (step S16) and store memory 6.
However, when Nc<nc, subroutine SUB4 is executed, and then nc is reset (nc=
0) (step S17) and returns to step S1.

Overflow check algorithm (see FIG. 5)
The algorithm of the overflow check subroutine SUB4 is shown in FIG. S31), and the measurement start flag F is read from the memory 3 (step S32).

[0035] Then, this measurement start flag F is "1".
It is determined whether or not, that is, whether only the first cell after the start of measurement is currently being detected or whether the next cell is being detected (step S33), and when F=1, the first cell is detected. Since this is not the state, the process advances to step S39, where Ac is incremented, and Ac and F at the next address (VPI number) in the memory 3 are read out.

However, when it is determined in step S33 that the flag F=1, the current time t is obtained from the timer 2 (step S34) and the cell before the specified VPI number is in the first cell state. The cell arrival time to is read from the memory 3 (step S35) and the arrival time interval T=t-to is calculated (step S36).
).

[0037] Then, the most significant bit (MSB) of the calculated arrival time interval T expressed as data bits is "1".
” (step S37), and 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).
. Note that this subroutine SUB4 ends when all addresses Ac have been specified, and returns to step S1 in FIG.
We will move on to 7.

Here, the meaning of determining whether the most significant bit of the arrival time interval T is "1" is that the first cell arrives and half of the maximum time indicated as the arrival time to in the memory 3. This indicates that it is being determined whether or not the period has passed. This is because the VPI numbers in the memory 3 exist from 0 to m, so if step S37 is determined based on the maximum allowable arrival time interval expressed as the arrival time to, it is necessary to check the arrival time interval T of a certain VPI number. This is because the arrival time interval T of another VPI number will exceed its maximum allowable time interval when Therefore, the most significant bit at this time corresponds to the predetermined measurement allowable time.

Result reading processing algorithm (see FIG. 6) As shown in FIG. 6, in the subroutine SUB2 of the result reading processing shown in FIG. 2, the input/output unit 1 first sets a read address for the memory 3 (step S41). , the number of violations n of the VPI number corresponding to this address is read out (step S
42), it is determined whether this n is "0" (step S43).

In this case, if n=0, since no violation has occurred, the process advances to step S46, and then to step S4.
Returning to 1, it is determined whether n of the next address is "0" or not. Then, when n=0, the Vp of that address
is read out (step S44) and notified to the control unit (not shown) (step S45). In this way, the input/output unit 1 executes the read process for all VPI numbers.

In the above embodiment, the overflow check memory 5 is provided separately from the memory 3 for processing, but the memory 5 can achieve the same function even if it is built into the traffic measurement section 4. be able to.

[0042]

As described above, according to the ATM transmission network monitoring method according to the present invention, each node stores in memory the time of the first cell that arrives after the start of measurement, and from this time the next cell with the same identifier If a predetermined allowable measurement time elapses before a cell arrives, it is determined that there is an abnormality and the measurement is repeated, so the arrival time of the previous cell can be saved in memory, and the There is no need to provide a register in the memory, which reduces the circuit scale, and even when cells arrive that exceed the storage limit of the physical arrival time interval of the memory, an incorrect cell flow rate result is not produced, and the cell flow rate is accurate. can be given.

[Brief explanation of drawings]

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

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

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

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

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

FIG. 6 is a flowchart for explaining an algorithm of measurement result read processing 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 the arrival time interval of ATM cells.

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

[Explanation of symbols]

1 Input/output section 2 Timer 3 Memory for measurement work and result storage 4 Traffic measurement section 5 Memory for overflow check work In the diagram, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] [Claim 1] An input/output unit (1) for setting initial values and outputting measurement results, a timer (2) for generating time, a memory (3) for both measurement work and result storage, and a Detects the cell that has arrived for the first time, writes the time from the timer (2) in the memory (3) for each identifier, and allows a predetermined measurement allowable time to elapse before the next cell with the same identifier arrives. A monitoring system for an ATM transmission network, characterized in that each node is equipped with a traffic measuring unit (4) that re-does the measurement when an abnormality occurs. 2. The initial value includes a lower limit value for the time interval of arriving cells, and the traffic measuring unit (4) determines that the arrival time interval between two cells with the same identifier after the start of measurement is equal to or less than the lower limit value. Claim 1 characterized in that the number of violations is stored in the memory (3) as a violation at a certain time, and the number of violations and its identifier are outputted from the input/output section (1) when the measurement is completed. The ATM transmission network monitoring method described in . 3. The traffic measurement unit (4) stores the minimum value of the violation arrival time interval together with the violation count in the memory (3), and when the measurement ends, the minimum arrival time interval is also stored in the input/output unit. 3. The ATM transmission network monitoring system according to claim 2, wherein the ATM transmission network is output from (1). 4. When the memory (3) is used as a first memory, a second memory (5) for overflow check work that stores address management values for each cell identifier in the first memory (3) is provided. ), the traffic measurement unit (4) detects the cell that arrives for the first time after the start of measurement for each identifier in the first memory (3) according to the address managed in the second memory (5). 4. The ATM transmission network monitoring method according to claim 1, wherein said measurement is re-performed when a predetermined time has elapsed from the time when the next cell arrives.