JPH08307421A - Continuity test method - Google Patents

Abstract

PURPOSE: To provide a continuity test method which can improve the accuracy of the test measurement result and also can make clear the errors on a transmission line. CONSTITUTION: The presence of cells that are lost before a test object cell #N are decided when the sequence numbers SN are continuous to each other between the test object cells following the cell #N by one and two cells respectively (24 and 25). If the SNs are continuous among a test object cell (#N-1) right before the cell #N, a test object cell (#N+1) following the cell #N by one, and a test object cell (#N+2) following the cell #N by two respectively, the received test object cell is decided as the erroneously distributed one (27, 28). Then the cell #N is decided as the erroneously distributed one and also the presence of a lost cell is decided when the internal reference value SNR set at a receiving part when the cell #N is received is continuous to the SNs of both cells (#N+1) and (#N+2) (30, 31).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuity test method, and particularly to an asynchronous transfer mode (ATM: Asynchronous Tra) in which communication is performed using a virtual path (VP).
The present invention relates to a VP continuity test method in a communication device.

[0002]

2. Description of the Related Art Generally, CCITT is used in ATM communication devices.
Recommendation I. As defined in 610, in order to maintain and manage the network, OAM (Operation, Adm)
initiation and Maintenan
ce) cell is defined, and the conduction of the virtual path (VP) set on the transmission side and the reception side is confirmed by the test target cell having the configuration in which the test pseudo-random pattern and the sequence number are inserted in the OAM cell. , The failure section is separated and the characteristics of the set VP are measured.

As a method of testing the continuity of this VP by the conventional ATM communication device, the transmitting side inserts the PN pattern and the sequence number into the OAM cell and transmits through the VP, and the receiving side detects the PN pattern and bit error occurs. There is known a test method in which the sequence number is detected, the sequence number is detected, and when there is an error in the sequence number, it is counted as an abnormal cell and the counting of bit errors is stopped (Japanese Patent Laid-Open No. 5-244196). Gazette).

In this conventional continuity test method, the number of test target cells received immediately before is sequentially counted by the sequence number counter, and the count result of this counter and the sequence number extracted from the test target cell are compared with the sequence number. It is determined by the circuit that if the two match, it is determined to be normal, and if the two do not match, it is determined that an erroneous cell or a lost cell has occurred.

[0005]

However, in the above-mentioned conventional continuity test method in the ATM communication device, the judgment is made even when the cell to be tested is an erroneously distributed cell, and it is impossible to make an accurate judgment. There is a problem. Also, VP
In the characteristic test, the number of cells to be tested for PN out-of-sync or sequence number error is not counted as the total number of cells, and since it does not have a parameter as a counting target, the number of error cells actually occurring on the transmission line is clarified. There is a problem that you can not.

The present invention has been made in view of the above points,
An object of the present invention is to provide a continuity test method capable of improving accuracy of test measurement results and clarifying errors on a transmission line.

[0007]

In order to achieve the above object, the present invention asynchronously synchronizes a test target cell in which a test pseudo random pattern and a sequence number whose value is cyclically updated in a cell unit are inserted. The first test received by comparing the sequence number reference value updated at every reception of the test target cell with the sequence number in the received test target cell by transmitting / receiving via the virtual path of the transfer mode When a comparison result that the sequence number of the target cell does not match the sequence number reference value is obtained, the first test target cell and the second test received 1 cell and 2 cells after the first test target cell, respectively. Three test target cells including a third test target cell, or a fourth test target cell received one cell before the first test target cell and second and third test target cells Based on the continuity of the sequence numbers of the three test target cells including the test target cell and the sequence number reference value at the time of receiving the first test target cell, the presence / absence of mis-distributed cells and lost cells is determined. It is a thing.

Further, in the method of the present invention, the presence or absence of the mis-distributed cell and the lost cell is determined by checking the received test target cell
The test target cell before the cell and the pseudo random pattern generated by the receiving unit are compared and collated only when it is determined that they are synchronized, and the received test target cell and the cell one cell before As a result of comparison and comparison between both test pseudo-random patterns of the test cell and the pseudo-random pattern generated by the receiving unit, if it is determined that both are out of synchronization, the received test cell is discarded.

Further, in the method of the present invention, the number of discarded test target cells and the number of test target cells determined to be inconsistent with the sequence number are included in the total number of received test target cells and counted, and discarded with respect to the total number of test target cells. The measurement is terminated when the ratio of the number of test target cells is equal to or more than the arbitrarily set threshold value.

[0010]

In the method of the present invention, when a comparison result is obtained in which the received sequence number of the first test target cell does not match the sequence number reference value, it is further received after or immediately before the first test target cell. Based on the sequence number continuity of all three test target cells or the sequence number reference value at the time of receiving the first test target cell and the sequence number continuity of the remaining two test target cells Further, since the presence / absence of loss cells is determined, it is possible to accurately determine the occurrence of mis-distributed cells and loss cells.

Further, in the method of the present invention, both the received test target cell and the test random cells of the test target cell one cell before the test pseudo random pattern and the comparison result of the pseudo random pattern generated by the receiving section are both synchronized. When it is determined that the test target cell is out of sync, the received test target cell is discarded.
It is possible to determine whether or not there is an erroneously distributed cell or a lost cell.

Further, in the method of the present invention, since the number of discarded test target cells and the number of test target cells determined to have a sequence number mismatch are included in the total number of test target cells received, the cell-based transmission is performed. It is possible to clarify the error on the road, and to have the monitoring function for the transmission line error by ending the measurement when the ratio of the number of discarded test target cells to the total number of test target cells is equal to or more than the arbitrarily set threshold value. You can

[0013]

Next, an embodiment of the present invention will be described. FIG. 1 shows a flowchart for explaining the operation of one embodiment of the present invention. In the present embodiment, in the ATM communication device in which the transmitting side and the receiving side transmit and receive cells via the VP, the sequence numbers of the received test target cell and the next received test target cell are compared, and the determination result is 0 < When D ≦ 15, the loss / misdelivery is determined after confirming the sequence numbers of the cells to be tested up to two cells later.

First, the receiving section receives a cell to be tested (step 11). This test target cell is an OAM cell that is a pseudo random number (PN: Pseudo Random Number).
er) pattern and sequence number (hereinafter referred to as SN) are inserted as in the conventional case. When the receiving unit receives the test target cell, the reference sequence number SNR of the sequence number counter in the receiving unit is set to "
1 "is added (step 12), and the value of the received total cell number TC is also added by" 1 "(step 13).

Next, it is judged whether or not the cell received immediately before (that is, normally the # N-1 test target cell when the #N test target cell is received in step 11) is out of PN synchronization ( Step 14). This is to compare and collate the received PN synchronization pattern in the test target cell with the same PN pattern as the transmission unit generated in the reception unit. If they match, it is determined that the PN synchronization is not lost, and if they do not match, PN synchronization is detected. It is determined to be out. When the receiving unit determines in step 14 that the PN synchronization is not lost, it substitutes the error bit number of the received test target cell into the variable Eb (step 15), and then the test target cell received in step 11 is out of PN synchronization. Is determined in the same manner as in step 14 (step 16).

When it is determined that the cell to be tested received this time has not lost PN synchronization, it is determined whether or not a sequence number (SN) error has occurred (step 17). This compares and contrasts the reference sequence number SNR of the sequence number counter in the receiving unit with the SN in the received test target cell, and when both match, it is determined that SN error does not occur, and when they do not match, SN error occurs. To do.

When it is determined in step 17 that the SN error has not occurred, "16 + SN-SNR" (m
od. The calculation result of the calculation expression represented by 16) is set as the value of the loss D (step 18). That is, since the SN in the cell to be tested and the count value (SNR) of the sequence number counter in the receiving unit take cyclical values of "0" to "15", respectively, the error between the SN and SNR is " 1
The value D of modulo 16, which is a value obtained by adding "6", is regarded as a loss.

Then, it is judged whether the loss D is 0 or a value within the range of 0 <D≤15 (step 19). The SN in the cell under test and the S in the receiving section that are received during normal operation
Since NR indicates the same value, D = 16 = 0 (mod. 1
6). Therefore, at this time, it is determined to be normal (step 20), and then it is determined whether or not the variable Eb of the error bit number of the payload of the reception test target cell is positive (step 21).

When Eb is positive, the value indicates the number of error bits of the received test target cell as shown in step 15. Therefore, the variable Eb is added to the error bit number EB before that. The value is the current error bit number EB
And the variable Eb is reset to the initial value "0" (step 22). Then, the error cell count EC
Is incremented by "1" to end the process once (step 2
3). When Eb is 0, there is no erroneous cell number, so the process is once terminated to prepare for the next measurement (step 23).

On the other hand, in step 19, the loss D is 0 <D ≦ 1.
When it is determined that the value is within the range of 5, not only the Nth test target cell #N received in step 11,
Further, after waiting for reception of the test target cell (# N + 1) after one cell and the test target cell (# N + 2) after two cells, the mis-distributed cell and the lost cell are determined from these three cells.

That is, first, it is determined whether or not the SNs of three consecutive cells #N, # N + 1 and # N + 2 are consecutive (step 24). As shown in FIG. 2, the SN of the #N test target cell should be the same “n” as the SNR, which is different from “x”, but the SN of the # N + 1 and # N + 2 test target cells is the #N test. X which is the SN of the target cell
If there is a continuous change to “x + 1” and “x + 2”, it is determined that there is a loss cell before the #N test target cell.

Therefore, in this case, after updating the number of lost cells LC to a value obtained by adding the number of lost cells LC before that to the value of the current loss D (step 25), the value of the SNR of the counter in the receiving section is updated. The received SN of the test target cell #N is changed to the value x (step 26). As a result, as shown in FIG. 2, the SNs of the test target cells # N + 1 and # N + 2 are “x + 1” and “x + 2”, respectively. The loss value D in this case is y (= 16 + x−n).

In step 24, #N, #N consecutive
When it is determined that the SNs of the three cells of +1 and # N + 2 are not continuous, the N received in step 11 is next.
The test target cell immediately before the th test target cell #N (# N-
1) It is determined whether the SNs of the test target cell (# N + 1) after one cell and the test target cell (# N + 2) after two cells are continuous (step 27). That is, although the SN of the test cell of #N should be the same as the SNR, that is, “n”, it is different from “x”, but as shown in FIG. 3, the test cell (# N−1), one cell later Test target cell (#N
+1) and each S of the test target cell (# N + 2) after 2 cells
When N is continuous with “n”, “n + 1”, and “n + 2”, only the received test target cell (#N) is incorrect, and this is determined to be an erroneous cell.

Therefore, in this case, after adding "1" to the value of the number MC of mis-distributed cells (step 28), the value of SN "n-" of # N-1 which seems to be correct as the value of SNR.
1 ”is substituted (step 29). As a result, as shown in FIG. 3, the SNs of the test target cells # N + 1 and # N + 2 are increased.
Are "n" and "n + 1", respectively. The loss value D in this case is y (= 16 + x−n).

Furthermore, in step 27, the test target cell (# N-1) immediately before the Nth test target cell #N, the test target cell (# N + 1) one cell later and the test target cell (# N + 1) two cells later. If it is determined that each SN of (N + 2) is not continuous, the SNR value when the Nth test target cell #N is received in step 11 and the test target cell (# N + 1) one cell after #N. SN and cell under test after 2 cells (#N
It is determined whether the SN of +2) is continuous (step 30).

That is, although the SN of the cell under test of #N should be the same as the SNR, that is, "n", it is different from "x", but as shown in FIG. 4, when the cell under test #N is received. The SNR value is “n”, the SN value of the test target cell (# N + 1) after one cell #N is “n + 1”, and the SN value of the test target cell (# N + 2) after two cells is “n +”.
2 ”consecutively, it is determined that the test cell #N is a mis-distributed cell and that a loss cell exists.

Therefore, in this case, the value of the number of lost cells LC is updated to the value obtained by adding the value of the loss D to the previous value, and the value of the number of mis-distributed cells MC is added to the previous value by "1". The updated value is updated (step 31). As a result, as shown in FIG. 4, the SNs of the test target cells # N + 1 and # N + 2 are “n + 1” and “n + 2”, respectively. The loss value D in this case is y (= 16 + x−) as in FIGS. 2 and 3.
n).

When any one of the steps 26, 29 and 31 is completed, the above-mentioned step 21 is followed.
It is determined whether the error bit number Eb of the payload is positive, and when it is positive, the error bit number Eb before that is determined.
The value obtained by adding the variable Eb to B is updated to the current error bit number EB, and the variable Eb is set to the initial value "0" (step 22). After that, set the error cell count EC
1 "is added and the process is temporarily terminated (step 23).
When b is 0, the process is temporarily terminated.

On the other hand, in step 30, the SNR at the time of receiving the test target cell #N and each S of the test target # N + 1 and # N + 2.
When it is determined that N is discontinuous, it is determined that the measurement result is abnormal and the measurement ends (step 32).

When it is determined in step 14 that the immediately preceding cell is out of PN synchronization (step 1
4) PN re-synchronization is performed by comparing and collating the PN pattern of the test target cell #N after one cell with the PN pattern from the PN pattern generator of the receiving unit (step 33). It is determined whether or not the synchronization is lost (step 34), and when the synchronization is achieved, the process proceeds to step 15.

If PN synchronization is still lost,
This time, it is judged whether or not the rest of the payload is present (step 35), and when the rest is present, PN resynchronization is performed again (step 33). When the rest of the payload does not exist, the received cell under test is abnormal, so
The received cell is discarded by adding "1" to the variable DC of the number of discarded cells (step 36). As a result, the number of transmitted test target cells and the total number of received test target cells can be matched. Then, the transmission path error rate ε is calculated by DC / TC.
Is calculated (step 37), and it is determined whether the transmission path error rate ε is equal to or more than the threshold value X (step 3).
8). When ε is equal to or greater than X, it is determined that there is an abnormality in the transmission path, and the measurement is terminated (step 39). When ε is less than X, the process is temporarily terminated to measure the next cell to be tested. Prepare

[0032]

As described above, according to the present invention,
When a comparison result is obtained in which the sequence number of the received first test target cell does not match the sequence number reference value, a total of three test target cells are received after or immediately before the first test target cell. Of the occurrence of mis-distributed cells and lost cells based on the continuity of the sequence numbers of the first test target cell or the continuity of the sequence number reference value at the time of receiving the first test target cell and the sequence numbers of the remaining two test target cells. By making a decision,
A more accurate continuity test can be performed based on the accurate determination of the occurrence of mis-distributed cells and loss cells.

Further, according to the method of the present invention, when it is determined that the received test object cell and the test object cell one cell before the cell are out of synchronization, the received test object cell is discarded to synchronize. Since it is determined whether or not the mis-distributed cells and the loss cells are generated only for the test target cell that does not cause the disconnection, an accurate continuity test can be performed.

Furthermore, according to the method of the present invention, by counting the number of discarded test target cells and the number of test target cells determined to have sequence number mismatches in the total number of received test target cells, counting is performed. The error on the transmission line can be clarified, and the measurement function is terminated when the ratio of the number of discarded test target cells to the total number of test target cells is equal to or greater than the arbitrarily set threshold value, thus providing a monitoring function for transmission line errors. By doing so, it is possible to clarify the number of erroneous cells on the transmission path that are actually occurring, and to realize accurate measurement.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining the operation of an embodiment of the present invention.

FIG. 2 is an explanatory diagram when the sequence numbers of test target cells #N, # N + 1 and # N + 2 are consecutive.

FIG. 3 is a diagram showing test target cells # N-1, # N + 1 and # N + 2.
FIG. 7 is an explanatory diagram of a case where the sequence numbers of are consecutive.

FIG. 4 is an explanatory diagram when a sequence number reference value of a test target cell #N, a sequence number of a test target cell # N + 1, and a sequence number of a test target cell # N + 2 are consecutive.

[Explanation of symbols]

11-39 Processing Steps of the Method of the Present Invention # N-2, # N-1, #N, # N + 1, # N + 2 Test Cell SN Sequence Number SNR Sequence Number Reference Value D Loss

Claims (6)

[Claims] 1. A test target cell in which a test pseudo-random pattern and a sequence number whose value is sequentially cyclically updated in a cell unit are transmitted and received via a virtual path in an asynchronous transfer mode, and the receiving side is configured to The sequence number reference value updated each time the test target cell is received is compared with the received sequence number in the test target cell, and the received sequence number of the first test target cell does not match the sequence number reference value. 3 when the comparison result is obtained, the first test target cell and the second and third test target cells received 1 cell and 2 cells after the first test target cell, respectively. Three test target cells, or four test target cells received one cell before the first test target cell and the second and third test target cells Continuity characterized in that the presence or absence of mis-distributed cells and lost cells is determined based on the continuity of the sequence number of the test target cell and the sequence number reference value when the first test target cell is received. Test method. 2. The presence or absence of the mis-distributed cell and the loss cell is determined by the test pseudo random pattern of the test target cell one cell before the received test target cell and the pseudo random pattern generated by the receiving unit. Only when it is determined to be in synchronization by comparison and collation with, the test pseudo random pattern for both the received test target cell and the test target cell one cell before that and the pseudo random pattern generated by the receiving unit. 2. The continuity test method according to claim 1, wherein the received test target cell is discarded when it is determined as out of synchronization as a result of comparison and collation with. 3. The total number of test target cells received and the number of test target cells discarded and the number of test target cells determined to be inconsistent with the sequence number are counted and discarded with respect to the total number of test target cells. The continuity test method according to claim 2, wherein the measurement is terminated when the ratio of the number of cells to be tested is equal to or more than a threshold value set arbitrarily. 4. When the sequence numbers of the first to third test target cells are consecutive, the first test target cell is counted as a lost cell, and when the first test target cell is received, The first as the sequence number reference value
2. The continuity test method according to claim 1, wherein the sequence number of the test target cell is substituted. 5. When the sequence numbers of the fourth test target cell and the second and third test target cells are consecutive, the first test target cell is counted as a mis-distributed cell, and 2. The continuity test method according to claim 1, wherein the sequence number of the fourth test target cell is substituted as a sequence number reference value when the first test target cell is received. 6. The first test target cell is erroneous when the sequence number reference value at the time of receiving the first test target cell and each sequence number of the second and third test target cells are continuous. The continuity test method according to claim 1, wherein counting is performed as distribution cells and loss cells.