JP2738339B2 - Continuity test method - Google Patents

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 more particularly to an asynchronous transfer mode (ATM) for performing communication using a virtual path (VP).
nsferMode) in a communication device.

[0002]

2. Description of the Related Art Generally, a CCITT is used in an ATM communication device.
Recommendation I. As specified in 610, OAM (Operation, Adm)
initialization and Maintenan
ce) A cell is defined, and conduction of a virtual path (VP) set on the transmission side and the reception side is confirmed by a test target cell having a configuration in which a test pseudo random pattern and a sequence number are inserted into an OAM cell. , The fault section is isolated, and the characteristics of the set VP are measured.

As a continuity test method of this VP by a conventional ATM communication device, a transmitting side inserts a PN pattern and a sequence number into an OAM cell and transmits it via the VP, and a receiving side detects the PN pattern and detects a bit error. A test method is known in which a sequence number is detected, a sequence number is detected, and when there is an error in the sequence number, the cell 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 cells to be tested received immediately before is sequentially counted by a sequence number counter, and the count result of this counter is compared with the sequence number extracted from the cells to be tested by sequence number collation. The matching is performed by a circuit. If the two match, it is determined that the cell is normal. If the two do not match, it is determined that an erroneously distributed cell or a lost cell has occurred.

[0005]

However, in the above-described continuity test method in the conventional ATM communication device, a determination is made even when a test target cell is an erroneously distributed cell, and accurate determination is impossible. There is a problem. Also, VP
In the characteristic test, the cells to be tested for PN loss of synchronization or sequence number error are not counted as the total number of cells, and since there are no parameters to be counted, the number of error cells on the transmission line that actually occur is clarified. There is a problem that can not be.

[0006] 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 the accuracy of a measurement result of a test and clarifying an error on a transmission path.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for asynchronously synchronizing a test object cell into which a pseudo random pattern for test and a sequence number whose value is updated cyclically in units of cells are inserted. The first test is transmitted and received via the virtual path in the transfer mode, and the receiving side compares the sequence number reference value updated each time the test target cell is received with the sequence number in the received test target cell. When a comparison result indicating that the sequence number of the target cell does not match the sequence number reference value is obtained, the first and second test cells that are received one and two cells after the first test target cell, respectively. Each sequence of three test cells including a third test cell
The first continuity of the S-number and one of the first cells under test
The fourth cell under test received before the cell and the second and third cells
Each Sea <br/> Ken Graphics and second continuity of the license, the first tested cell receiving time sequence number reference value and the second and third of trial the tested cells three tested cell comprising
Based on the third continuity with each sequence number of test target cells, have <br/> line determines the presence or absence of occurrence of miscarriage cells and loss cell, first to third continuity discontinuous All Is determined
When the measurement is completed, the measurement is forcibly terminated .

Further, in the method of the present invention, whether or not an erroneously distributed cell and a lost cell have occurred is determined by one of the received test target cells.
Performed only when it is determined by the comparison and comparison between the test pseudo-random pattern of the test target cell before the cell and the pseudo-random pattern generated by the receiving unit that they are synchronized, and As a result of comparison and comparison between the pseudo random patterns for both tests of the test target cell and the pseudo random pattern generated by the receiving unit, if both are determined to be out of synchronization, the received test target cell is discarded.

Further, in the method of the present invention, the number of discarded test cells and the number of test cells determined to have a sequence number mismatch are counted as being included in the total number of received test cells, and discarded for the total number of test cells. The measurement is terminated when the ratio of the number of cells to be tested is equal to or greater than an arbitrarily set threshold value.

[0010]

According to the method of the present invention, when a comparison result indicating that the received sequence number of the first cell to be tested does not match the sequence number reference value is obtained, the received data is further received after or immediately before the first cell to be tested. The first and second of each sequence number of all three test cells
The continuity, the sequence number reference value at the time of receiving the first test target cell, and the respective sequences of the second and third test target cells
Since the presence / absence of an erroneously distributed cell and a lost cell is determined based on the third continuity with the S-number, the occurrence of the erroneously distributed cell and the lost cell can be accurately determined. Change
In addition, in the present invention, all of the first to third continuities are non-continuous.
When it is determined that the measurement is continued, the measurement is forcibly terminated. Measurement result
This is because the result can be determined to be abnormal.

In the method of the present invention, the results of comparison and comparison between the received pseudo-random pattern for the test and the pseudo-random pattern for the test immediately before the cell to be tested and the pseudo-random pattern generated by the receiving section are all synchronized. When it is determined that the cell is lost, the received cell under test is discarded.
It is possible to determine whether or not an erroneously distributed cell and a lost cell have occurred.

Furthermore, in the method of the present invention, the number of discarded test cells and the number of test cells determined to have mismatched sequence numbers are included in the total number of received test cells and counted. Having a monitoring function for transmission line errors by clarifying errors on the path and terminating the measurement when the ratio of the number of discarded test cells to the total number of test cells is equal to or greater than an arbitrarily set threshold value Can be.

[0013]

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

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

Next, it is determined whether the cell received immediately before (that is, the cell to be tested # N-1 when the cell to be tested #N is received in step 11) is out of PN synchronization (or not). Step 14). This is because the PN synchronization pattern in the received test target cell is compared with the same PN pattern generated by the receiving unit and the same as the transmitting unit, and when they match, it is determined that the PN synchronization is not out of sync. It is determined to be out. If the receiving unit determines in step 14 that the PN synchronization has not been lost, the receiving unit substitutes the number of error bits of the received test target cell into a variable Eb (step 15), and determines whether the test target cell received in step 11 has lost PN synchronization. Is determined in the same manner as in step 14 (step 16).

If it is determined that the test target cell received this time has not lost PN synchronization, it is determined whether a sequence number (SN) error has occurred (step 17). This is performed by comparing and comparing the reference sequence number SNR of the sequence number counter in the receiving unit with the SN in the received test target cell, and determining that there is no SN error if they match, and that an SN error has occurred if they do not match. Is what you do.

If it is determined in step 17 that no SN error has 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 under test and the count value (SNR) of the sequence number counter in the receiving unit sequentially take values of “0” to “15” sequentially, the error between the SN and SNR is “ 1
The value D of the modulo 16 obtained by adding "6" is regarded as a loss.

Subsequently, it is determined whether or not the loss D is 0 or a value within the range of 0 <D ≦ 15 (step 19). In the normal state, the SN in the cell to be tested and the S in the receiver are received.
Since NR indicates the same value, D = 16 = 0 (mod. 1)
6), so that it is determined to be normal (step 20), and then it is determined whether the variable Eb of the number of error bits in the payload of the cell to be tested for reception 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, so that the above variable Eb is added to the number of error bits EB before that. The value is the current error bit number EB
And reset the variable Eb to the initial value "0" (step 22). Then, the error cell number EC
Is added to “1” and the processing is temporarily terminated (step 2
3). When Eb is 0, there is no error cell number, so the process is temporarily 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 but also
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, a determination is made from these three cells as to an incorrectly distributed cell or a lost cell.

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

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 the current value of the loss D to the value of the previous loss D (step 25), the value of the SNR of the counter in the receiving unit is changed. The received value is changed to the SN value x of the test target cell #N (step 26). Thereby, as shown in FIG. 2, the SNs of the test target cells # N + 1 and # N + 2 become "x + 1" and "x + 2", respectively. The value D of the loss in this case is y (= 16 + x−n).

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

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

Further, at step 27, the test target cell (# N-1) immediately before the N-th test target cell #N, the test target cell (# N + 1) after one cell, and the test target cell (#N) two cells after When it is determined that each SN of (N + 2) is not continuous, the value of the SNR when the Nth test cell #N is received in step 11 and the value of the test cell (# N + 1) one cell after #N SN and the cell to be tested after two cells (#N
It is determined whether the SN of (+2) is continuous (step 30).

That is, although the SN of the cell under test #N should be originally “n” which is the same as the SNR, it is different from “x”. However, as shown in FIG. The SNR value is “n”, the SN value of the test cell (# N + 1) one cell after #N is “n + 1”, and the SN value of the test cell (# N + 2) two cells after is “n +
When "2" is continuous, it is determined that the test target cell #N is an erroneously distributed cell and that a lost cell exists.

Therefore, in this case, the value of the number of lost cells LC is updated to a 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 with “1” to the previous value. 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 become “n + 1” and “n + 2”, respectively. The loss value D in this case is y (= 16 + x−) as in FIGS.
n).

If any one of the steps 26, 29 and 31 is completed, the process proceeds to the step 21
To determine whether the number Eb of error bits of the payload is positive.
The value obtained by adding the above 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, the error cell number EC is changed to "
1 "is added and the process is once ended (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 SNR of the test target # N + 1 and # N + 2
When N is determined to be discontinuous, the measurement is determined to be abnormal and the measurement is terminated (step 32).

When it is determined in step 14 that the immediately preceding cell is out of PN synchronization (step 1).
4) PN resynchronization is performed to compare and match 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 has been lost (step 34). If the synchronization has been established, the process proceeds to step 15 described above.

If the PN synchronization is still lost,
This time, it is determined whether or not the rest of the payload exists (step 35), and if there is, the PN resynchronization is performed again (step 33). When the rest of the payload does not exist, the received cell under test is abnormal,
The received cell is discarded by adding "1" to the variable DC of the discarded cell number (step 36). Thereby, 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
(Step 37), and it is determined whether or not the transmission path error rate ε is equal to or greater than a threshold value X (step 3).
8). When ε is equal to or larger than X, it is determined that the transmission path is abnormal, and the measurement is terminated (step 39). When ε is smaller than X, the process is temporarily terminated and the measurement is performed for the next cell to be tested. Prepare.

[0032]

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

Further, according to the method of the present invention, when it is determined that both the received test target cell and the test target cell immediately before it are out of synchronization, the received test target cell is discarded, thereby achieving synchronization. Since only the test target cell that does not lose is determined whether or not there is a mis-distributed cell or a lost cell, an accurate continuity test can be performed.

Further, according to the method of the present invention, the number of discarded test cells and the number of test cells determined to have a sequence number mismatch are included in the received total number of test cells and counted, thereby providing a cell-based count. It is possible to clarify errors on the transmission path, and has a monitoring function for transmission path errors by terminating measurement when the ratio of the number of discarded test cells to the total number of test cells is equal to or greater than an arbitrarily set threshold. By doing so, the number of erroneous cells on the transmission line that actually occur can be clarified, and accurate measurement can be realized.

[Brief description of the drawings]

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

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

FIG. 3 shows test target cells # N-1, # N + 1, and # N + 2.
Is an explanatory diagram in the case where the sequence numbers are consecutive.

FIG. 4 is an explanatory diagram in a case where 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 continuous.

[Explanation of symbols]

11-39 Processing steps of the method of the present invention # N-2, # N-1, #N, # N + 1, # N + 2 Cell under test SN sequence number SNR sequence number reference value D loss

Claims (6)

(57) [Claims] 1. A test cell in which a test pseudo-random pattern and a sequence number whose value is updated cyclically in a cell unit are inserted and transmitted / received via a virtual path in an asynchronous transfer mode. A sequence number reference value updated each time a 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. When the comparison result is obtained, the first test target cell and the second and third test target cells received one cell after and two cells after the first test target cell, respectively. A first continuity of each sequence number of one cell under test;
Second continuity of each sequence number of three test cells including the fourth test cell and the second and third test cells received one cell before the cell to be tested .
And the sequence number reference value at the time of receiving the first test target cell and each of the second and third test target cells.
Based on the third continuity with over Ken scan number, have rows determines the presence or absence of occurrence of miscarriage cells and loss cell, the first乃
Measured when all 3rd continuity is determined to be discontinuous
Forcibly terminating the test. 2. The method according to claim 1, wherein the determination of the presence / absence of the mis-distributed cell and the lost cell includes determining the test pseudo-random pattern of the test cell one cell before the received test cell and the pseudo-random pattern generated by the receiving unit. The test is performed only when it is determined that the cell is synchronized by comparing and comparing the pseudo-random pattern for the test and the pseudo-random pattern generated by the receiving unit for the received test target cell and the test target cell one cell before. 2. The continuity test method according to claim 1, wherein, as a result of the comparison and collation, when it is determined that any of the cells is out of synchronization, the received test target cell is discarded. 3. The number of discarded test cells and the number of test cells determined to have a sequence number mismatch are counted as being included in the total number of test cells received, and the discarded number for the total number of test cells is counted. 3. 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 greater than an arbitrarily set threshold value. 4. When the sequence numbers of the first to third cells to be tested are consecutive, the first cell to be tested is counted as a lost cell, and the first cell to be tested is received at the time of reception of the first cell to be tested. As the sequence number reference value, the first
2. The continuity test method according to claim 1, wherein the sequence number of the cell to be tested 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 an incorrectly distributed cell, and 2. The continuity test method according to claim 1, wherein a sequence number of the fourth test cell is substituted as a sequence number reference value at the time of receiving the first test cell. 6. When the sequence number reference value at the time of receiving the first test cell and the sequence numbers of the second and third test cells are continuous, the first test cell is incorrect. 2. The continuity test method according to claim 1, wherein the cells are counted as a distribution cell and a loss cell.