JP3657459B2 - Failure notification cell generation circuit and failure notification cell generation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a failure notification cell generation circuit and a failure notification cell generation method for notifying a transmission line or path failure in an ATM (Asynchronous Transfer Mode) communication apparatus.
[0002]
[Prior art]
When a transmission line or path failure is detected in an ATM communication device constituting an ATM network, the failure is notified to all operating VP (Virtual Path) connections and VC (Virtual Channel) connections that are affected by the failure. It is necessary to generate an OAM (Operation and Maintenance) cell, that is, a failure notification cell.
[0003]
The failure notification cell includes an AIS (Alarm Indication Signal) cell for notifying a failure in the downstream direction of the failure and an RDI (Remote Defect Indication) cell for notifying the failure in the opposite direction.
The generation cycle of the failure notification cell is 1 cell / second per connection. When a failure is detected, the generation of the failure notification cell must be started as quickly as possible. For the principle of such failure notification cell generation, see ITU-T Recommendation I.D. 610.
[0004]
Here, a method for generating a failure notification cell when a specific path failure is detected will be described.
Specific path failures include LOC (Loss of Continuity) detection in VP connections and VC connections, and VP-AIS alarm detection in VP connections.
[0005]
For example, Japanese Patent Laid-Open No. 10-70545 discloses a VP-FERF cell (= VP-RDI cell) transfer method (failure notification cell generation method) when a VP-AIS alarm is detected in an ATM network subscriber terminating device. FIG. 7 is an explanatory diagram showing the operation.
[0006]
The VP-AIS alarm detected by the ATM network terminal unit is detected when one VP-AIS cell is received for each VP connection, but when no VP-AIS cell is received for a certain period of time. Release the alarm.
At this time, the VP-AIS cell reception information and the non-reception timer information for the total number of VPs are usually realized by a memory for VP-AIS alarm management.
[0007]
When a VP-AIS cell is received, alarm detection is written to the corresponding VP number in the memory, and the memory is periodically accessed for alarm release, and the unreceived timer information and the alarm state are updated.
In the example of FIG. 7, the total number of VPs is N, and as shown in the VP-AIS alarm control target VP number, VP numbers = 1, 2, 3,. ··· The memory is accessed in the order of N and the alarm information is updated. At this time, the read alarm information is held in a 1-bit buffer for VP-FERF cell generation control.
[0008]
On the other hand, in the VP-FERF cell insertion control, VP-AIS for all VP connections per second is performed in order to perform VP-FERF cell insertion processing at one second intervals for the VP connection in which the VP-AIS alarm is detected. Check alarm information.
In the example of FIG. 7, as shown in the VP-FERF cell insertion control target VP number, the odd number of VP numbers (VP number = 1, 3, 5,... The alarm information is confirmed only for N-1), and the alarm information is confirmed only for even-numbered VP numbers (VP numbers = 2, 4, 6,..., N) for the second half of 0.5 seconds.
Furthermore, a 1-second clock for VP-FERF cell insertion control and a 0.5-second clock for VP-AIS alarm control are synchronized.
[0009]
As a result, the maximum phase difference between the VP-FERF cell insertion control target VP number and the VP-AIS alarm control target VP number becomes 1 VP or less. In the VP-FERF cell insertion control, the VP-AIS is not accessed again. The alarm information read out by the alarm control can be fetched as it is.
As described above, in the VP-FERF cell insertion control, the VP-AIS alarm information for all VP connections is confirmed per second at intervals of about 1 / N second, and the VP connection that detects the VP-AIS alarm is detected. VP-FERF cell insertion processing is performed.
[0010]
[Problems to be solved by the invention]
Since the conventional failure notification cell generation method is configured as described above, when a VP-AIS cell is received for a specific VP connection, a VP-AIS alarm control target VP is detected after detecting a VP-AIS alarm. It takes 0.5 seconds at maximum until alarm information is read out. In addition, in the VP-FERF cell insertion control, control is performed for 0.5 seconds by dividing into odd and even VP numbers. For example, even-numbered VP-reading during odd-numbered VP-FERF cell insertion control is performed. AIS alarm information is not captured, and VP-AIS alarm information is captured for the first time when even-numbered VP-FERF cell insertion control is performed 0.5 seconds later. In other words, a maximum of 1 second is required from the detection of a VP-AIS alarm for a specific VP connection until the VP-FERF cell insertion process is performed, and it takes a long time to generate a failure notification cell. It was.
This is a common problem in the method of confirming the failure once for every VP connection per second as in the conventional example and performing the failure notification cell generation control. The failure notification cell is detected after the failure is detected. It usually takes up to 1 second or more to occur.
[0011]
In addition, even if a VP-AIS alarm for a specific connection is detected, if the alarm is canceled before the VP alarm is confirmed by the VP-FERF cell insertion control, a VP-FERF cell is not generated. there were.
This is the same for all methods in which a failure for each connection is confirmed at regular intervals and a failure notification cell is generated only when a failure occurs. For example, when a VP failure is detected, a failure notification is sent to a plurality of VC connections included in the VP. When a cell is generated, if a VP failure is canceled before a failure notification cell is generated for all VC connections, a VC connection in which a failure notification cell is generated and a VC connection that does not occur are generated for the same failure. Will end up.
[0012]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a failure notification cell generation circuit and a failure notification cell generation method capable of generating a failure notification cell immediately after detection of a failure. And
The present invention also provides a failure notification cell generation circuit and a failure notification cell generation method capable of reliably generating a failure notification cell for all connections affected by a failure even if the failure is resolved in a short period of time. The purpose is to obtain.
[0013]
[Means for Solving the Problems]
The failure notification cell generating circuit according to the present invention adds a predetermined value to the common count value stored in the storage means, and when the added value matches the current common count value, the failure notification cell is set to the main signal cell. Insertion means for inserting into an empty cell is provided.
[0014]
The failure notification cell generation circuit according to the present invention is provided with insertion means for inserting the failure notification cell into an empty cell of the main signal cell as long as the added value matches the current common count value until the connection failure is resolved. It is a thing.
[0015]
The failure notification cell generation circuit according to the present invention is provided with insertion means for inserting the failure notification cell into the empty cell of the main signal cell only once even when the failure of the connection is eliminated before the failure notification cell is inserted. Is.
[0016]
The failure notification cell generation circuit according to the present invention is provided with a first occurrence flag which becomes valid when the failure detection means detects a connection failure, and becomes invalid when the insertion means inserts a failure notification cell into an empty cell of the main signal cell. Even when the connection failure is resolved, if the initial generation flag is valid, the failure notification cell is inserted into the empty cell of the main signal cell.
[0017]
In the failure notification cell generation method according to the present invention, a predetermined value is added to the common count value at the time of failure detection, and when the added value matches the current common count value, the failure notification cell becomes an empty cell of the main signal cell. It is designed to be inserted.
[0018]
The failure notification cell generation method according to the present invention inserts a failure notification cell into an empty cell of the main signal cell as long as the added value matches the current common count value until the connection failure is resolved. It is.
[0019]
The failure notification cell generation method according to the present invention is such that even when the connection failure is eliminated before the failure notification cell is inserted, the failure notification cell is inserted into the empty cell of the main signal cell only once. is there.
[0020]
The failure notification cell generation method according to the present invention is provided with a first occurrence flag that becomes effective when a connection failure is detected, but becomes invalid when a failure notification cell is inserted into an empty cell of the main signal cell, thereby eliminating the connection failure. Even if the initial generation flag is valid, the failure notification cell is inserted into the empty cell of the main signal cell.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a failure notification cell generation circuit according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 indicates that all OAM cells and user cells included in a main signal cell are monitored and all operations are in progress. A failure detection unit (failure detection unit) that determines a failure state for a VP connection or a VC connection, 2 is a failure management memory that holds the failure state determined by the failure detection unit 1 for all connections, “1” is written at the time of detection, and “0” is written at the time of failure release. Reference numeral 3 denotes a generation control memory (storage means) that holds the failure detection timing and the initial generation flag for all connections as information for controlling the generation of the failure notification cell. The failure detection timing is the timing at the time of failure detection for each connection. This is a value obtained by taking in the common count value output by the control unit 4, and the first generation flag is set to “1” when a failure is detected for each connection, and is set to “0” when the first failure notification cell insertion request for the failed connection is generated. Bit flag.
[0022]
4 is a 90 μs pulse signal indicating the minimum occurrence interval of the failure notification cell, a 1/2 second period pulse signal obtained by dividing the failure notification cell generation period of 1 second into two, and a common count value for identifying each of the two divided sections = 0. , 1, 0, 1,... Are generated and output, and the 1/2 second periodic pulse signal is generated in synchronization with the 90 μs pulse signal.
[0023]
5 inputs the 90 μs pulse signal and the 1/2 second period pulse signal generated by the timing control unit 4, and the connection numbers = 1, 2, 3,... A connection search unit to be generated. The connection search unit 5 reads data corresponding to the connection number from the connection table 6 and outputs the data and the connection number as connection information. However, in order to simplify the description, it is assumed that all usable VP connections or VC connections have numbers for identifying the connections. In the first embodiment, connection numbers = 1, 2, 3, ..., N.
6 is a valid / invalid flag indicating whether or not the connection corresponding to the connection number is in operation, a VP / VC flag indicating whether the connection is a VP connection or a VC connection, a VPI (Virtual Path Identifier), and a VCI. It is a connection table which memorize | stores (Virtual Channel Identifier).
[0024]
7 accesses the failure management memory 2 and the generation control memory 3 based on each pulse signal output from the timing control unit 4 and connection information output from the connection search unit 5, and connection numbers = 1, 2, 3, ..., the failure state corresponding to N, the failure detection timing, and the first occurrence flag are read, the failure state is “1” or the first occurrence flag is “1”, and “1” is set as the failure detection timing. When the added value matches the current common count value (when the failure detection timing and the current common count value are different), a failure notification cell insertion request is output to the failure notification cell insertion unit 8, and the first occurrence thereof When the flag is “1”, a failure notification cell generation control unit (insertion means) that cancels the initial generation flag to “0” when a failure notification cell insertion request is output, 8 is a failure When the intelligent cell generation control unit 7 outputs a failure notification cell insertion request, a failure notification cell is generated from the connection information output by the connection search unit 5, and the failure notification cell is inserted into an empty cell position of the main signal cell. It is a cell insertion part (insertion means).
[0025]
FIG. 2 is an explanatory diagram showing the internal configuration of the occurrence control memory 3. The occurrence control memory 3 holds a failure detection timing and an initial occurrence flag using the connection number as an address.
FIG. 3 is an explanatory diagram showing an operation example of the failure notification cell generation circuit according to the first embodiment, and FIG. 4 is a flowchart showing a failure notification cell generation method according to the first embodiment of the present invention.
[0026]
Next, the operation will be described.
As shown in FIG. 3, the common count value generated by the timing control unit 4 repeats 0, 1, 0, 1,... With a period of 1/2 second, and the failure notification cell generated by the connection search unit 5 is generated. The control connection number is counted up to 1, 2, 3,..., N at intervals of 90 μs in a 1/2 second period.
Further, the failure state for each connection determined by the failure detection unit 1, the corresponding failure detection timing and the initial generation flag are written in the failure management memory 2 or the generation control memory 3 with the connection number as an address, respectively. (Steps ST1 and ST2).
[0027]
Here, in the example of FIG. 3, the failure detection unit 1 sets the connection number = 2 and the second in the first period as the first period, the second period, the third period,... A fault with connection number = m is detected in the cycle, and a fault with connection number = m is cleared in the third cycle.
Therefore, in the example of FIG. 3, for connection number = 2, the failure state becomes “1” in the first period, and at the same time, the common count value “0” is displayed at the failure detection timing, and “ 1 "is written.
On the other hand, for the connection number = m, the failure state becomes “1” in the second period, and at the same time, “1” of the common count value is written in the failure detection timing and “1” is written in the first occurrence flag. However, when the failure state is canceled to “0” in the third period, the failure detection timing and the first occurrence flag do not change.
[0028]
First, generation control of a failure notification cell for a failure with connection number = 2 will be described.
When the failure information of connection number = 2 is confirmed in the first period, as described above, both the failure state and the first generation flag are “0”, so the failure notification cell generation control unit 7 The insertion request is not output to the failure notification cell insertion unit 8 (steps ST3 to ST5).
When the failure information of connection number = 2 is confirmed in the second period, the failure state and the first occurrence flag are “1”, and the failure detection timing “0” is different from the current common count value “1”. For this reason (because the added value “1” obtained by adding “1” to the failure detection timing “0” matches the current common count value “1”), the failure notification cell generation control unit 7 issues a failure notification cell insertion request. It outputs to the failure notification cell insertion unit 8 (steps ST3, ST6, ST7), and the first generation flag of connection number = 2 is canceled to “0”.
[0029]
In the third period, the failure state is “1”, but the failure detection timing “0” matches the current common count value “0” (adding “1” to the failure detection timing “0”) The failure notification cell generation control unit 7 does not output the failure notification cell insertion request to the failure notification cell insertion unit 8 (because the added value “1” does not match the current common count value “0”) (steps ST3 and ST6). , ST5).
In the fourth period, the first occurrence flag is “0”, but the failure state is “1”, and the failure detection timing “0” is different from the current common count value “1”. The generation control unit 7 outputs a failure notification cell insertion request to the failure notification cell insertion unit 8 (steps ST3, ST6, ST7).
Further, the fifth cycle is the same as the third cycle, and no failure notification cell insertion request is output (steps ST3, ST6, ST5).
[0030]
As described above, while the failure of the connection number = 2 continues, a failure notification cell insertion request is output to the failure notification cell insertion unit 8 at a cycle of 1 second for the connection number = 2, and the failure notification cell insertion unit 8 Inserts the failure notification cell into an empty cell position of the main signal cell (step ST8).
[0031]
Next, generation control of a failure notification cell for a failure with connection number = m will be described.
For the failure of connection number = m, the failure notification cell generation control unit 7 requests the failure notification cell insertion request because both the failure state and the first generation flag are “0” in the first cycle and the second cycle. Is not output to the failure notification cell insertion unit 8 (steps ST3 to ST5).
[0032]
When the failure information of connection number = m is confirmed in the third period, the failure state has already been cleared to “0”, but the initial generation flag is “1” and failure detection timing “1”. Is different from the current common count value “0”, the failure notification cell generation control unit 7 outputs a failure notification cell insertion request to the failure notification cell insertion unit 8 (steps ST3, ST4, ST6, ST7), and the connection number. = M First generation flag is reset to “0”.
After the fourth period, since both the failure state and the first occurrence flag are “0”, the failure notification cell insertion request is not output (steps ST3 to ST5).
[0033]
Thus, even if the failure is resolved before the failure of connection number = m occurs and the failure notification cell is generated, the failure notification cell insertion request is issued only once for the connection number = m. The failure notification cell insertion unit 8 inserts the failure notification cell at an empty cell position of the main signal cell (step ST8).
[0034]
As is apparent from the above, according to the first embodiment, the failure notification cell occurrence cycle of 1 second is divided into two by the common count value, and the common count value is set for each connection as a failure detection timing when a specific path failure is detected. By holding a failure notification cell insertion request when the failure detection timing and the common count value are different for the failed connection when the failure information for all connections is confirmed during the 1/2 second interval The generation cycle of the failure notification cell insertion request is 1 second for each connection, and the first failure notification cell insertion request can be generated within a maximum of 1 second from the failure detection.
[0035]
In addition, an initial generation flag is provided for each connection that is valid when a failure is detected for each connection and invalidated when a failure notification cell insertion request is first generated for the failure detection connection. When the occurrence flag is valid, a failure notification cell insertion request can be generated at least once even when there is a short-term failure by generating a failure notification cell insertion request.
[0036]
Embodiment 2. FIG.
In the second embodiment, for example, a method of generating failure notification cells for a plurality of VC connections when a VP failure is detected, such as VC-AIS cell generation by VP-AIS alarm detection, will be described.
[0037]
FIG. 5 is an explanatory diagram showing a configuration example of the connection table 6. In FIG. 5, the VPI values of the connection numbers = 1, 2, 3 are all “2”, and the final flag of the connection numbers = 1, 2 is “ The final flag of “0” and connection number = 3 is “1”. The final flag is a flag indicating the VC connection having the largest connection number among the VC connections included in the same VP (the VC connection having the latest failure notification cell generation control order).
[0038]
FIG. 6 is an explanatory diagram showing an operation example corresponding to the connection table 6 of FIG. 5. In FIG. 6, the failure state for each VP determined by the failure detection unit 1, the failure detection timing and the first occurrence flag corresponding thereto. Is written in each memory using the VPI value as an address instead of the connection number. Therefore, the failure notification cell generation control unit 7 uses the VPI value read from the connection table 6 as an address to check failure information corresponding to each connection number.
[0039]
In the example shown in FIG. 6, the failure state of VPI = 2 is “1” in the first period, and at the same time “0” of the common count value is written in the failure detection timing, and “1” is written in the initial generation flag. ing. However, when the failure state is canceled to “0” in the second period, the failure detection timing and the first occurrence flag do not change.
[0040]
Hereinafter, the generation control of the failure notification cell for the failure of VPI = 2 will be described. When the failure information of VPI = 2 corresponding to connection numbers = 1 to 3 is confirmed in the first period, both the failure state and the initial generation flag are “0”, so the failure notification cell generation control unit 7 The failure notification cell insertion request is not output to the failure notification cell insertion unit 8.
[0041]
When the failure information of VPI = 2 corresponding to the connection number = 1 is confirmed in the second period, the failure state and the first occurrence flag are “1”, and the failure detection timing “0” is the current common count value. Since it is different from “1”, the failure notification cell generation control unit 7 outputs a failure notification cell insertion request to the failure notification cell insertion unit 8.
At this time, since the final flag with connection number = 1 read from the connection table 6 is “0” and the VC connection with VPI = 2 still remains, the initial generation flag is not canceled.
[0042]
Next, when the failure information of VPI = 2 corresponding to the connection number = 2 is confirmed, the failure state is cleared to “0”, but the initial generation flag is “1” and the failure detection timing “ Since “0” is different from the current common count value “1”, the failure notification cell generation control unit 7 outputs a failure notification cell insertion request to the failure notification cell insertion unit 8. However, since the final flag of connection number = 2 is still “0”, the initial generation flag is not canceled.
[0043]
Finally, when the failure information of VPI = 2 corresponding to connection number = 3 is confirmed, a failure notification cell insertion request is output in the same manner as connection number 2. At this time, since the final flag of connection number = 3 is “1”, the initial generation flag is canceled to “0”.
From the third period onward, since both the failure state and the first occurrence flag are “0”, the failure notification cell insertion request is not output.
[0044]
As described above, according to the second embodiment, when a failure notification cell is generated for a plurality of VC connections when a VP failure is detected, failure notification cell generation control is performed in the VC connections included in the same VP. The last flag for identifying the VC connection with the latest order is stored in the connection table 6 and the first occurrence flag is only generated when a failure notification cell insertion request is first generated for a VC connection for which the last flag is valid. Is invalidated, a failure notification cell insertion request can be generated at least once for all VC connections included in a VP in which a failure is detected.
[0045]
【The invention's effect】
As described above, according to the present invention, when a predetermined value is added to the common count value stored in the storage means and the added value matches the current common count value, the failure notification cell is set to the main signal cell. Since the insertion means for inserting into the empty cell is provided, there is an effect that the failure notification cell can be generated promptly after the failure is detected.
[0046]
According to the present invention, until the connection failure is resolved, the insertion means for inserting the failure notification cell into the empty cell of the main signal cell is provided as long as the added value matches the current common count value. The failure notification cell can be generated periodically until the connection failure is resolved.
[0047]
According to this invention, even if the connection failure is resolved before the failure notification cell is inserted, the insertion means for inserting the failure notification cell into the empty cell of the main signal cell only once is provided. Even if the failure is resolved in a short period of time, there is an effect that a failure notification cell can be reliably generated for all connections affected by the failure.
[0048]
According to the present invention, the failure detection means is provided when the failure detection means detects a connection failure, while the insertion means provides an initial generation flag that becomes invalid when a failure notification cell is inserted into an empty cell of the main signal cell. Even if it is resolved, if the initial generation flag is valid, the failure notification cell is inserted into the empty cell of the main signal cell, so that the failure notification cell is generated without using a complicated configuration. There is an effect that can be done.
[0049]
According to the present invention, a predetermined value is added to the common count value at the time of failure detection, and when the added value matches the current common count value, the failure notification cell is inserted into an empty cell of the main signal cell. As a result, the failure notification cell can be generated promptly after the failure is detected.
[0050]
According to the present invention, the failure notification cell is inserted into the empty cell of the main signal cell as long as the added value matches the current common count value until the connection failure is eliminated. There is an effect that failure notification cells can be generated periodically until is resolved.
[0051]
According to the present invention, even when the failure of the connection is eliminated before the failure notification cell is inserted, the failure notification cell is inserted into the empty cell of the main signal cell only once, so that the failure is short-lived. Even if the problem is solved by (1), it is possible to reliably generate a failure notification cell for all connections affected by the failure.
[0052]
According to the present invention, the first generation flag that becomes valid when a connection failure is detected, but becomes invalid when a failure notification cell is inserted into an empty cell of the main signal cell, is provided even when the connection failure is resolved. If the first generation flag is valid, the failure notification cell is inserted into an empty cell of the main signal cell, so that it is possible to reliably generate the failure notification cell without using a complicated configuration. .
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a failure notification cell generating circuit according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an internal configuration of a generation control memory 3;
FIG. 3 is an explanatory diagram showing an operation example of the failure notification cell generation circuit according to the first embodiment;
FIG. 4 is a flowchart showing a failure notification cell generation method according to Embodiment 1 of the present invention.
FIG. 5 is an explanatory diagram showing a configuration example of a connection table 6;
6 is an explanatory diagram illustrating an operation example corresponding to the connection table 6 of FIG. 5;
FIG. 7 is an explanatory diagram showing an operation example of a conventional failure notification cell generation circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Failure detection part (failure detection means), 3 Generation control memory (storage means), 4 Timing control part (update means), 7 Failure notification cell generation control part (insertion means), 8 Failure notification cell insertion part (insertion means) ).

Claims (8)

Update means for updating the common count value a plurality of times per second, failure detection means for detecting a connection failure, and storage for storing a common count value at the time of failure detection when the failure detection means detects a connection failure And a means for adding a predetermined value to the common count value stored in the storage means and inserting a failure notification cell into an empty cell of the main signal cell when the added value matches the current common count value And a failure notification cell generating circuit. 2. The failure according to claim 1, wherein the insertion means inserts the failure notification cell into an empty cell of the main signal cell as long as the added value matches the current common count value until the connection failure is resolved. Notification cell generation circuit. The insertion means inserts the failure notification cell into the empty cell of the main signal cell only once even when the connection failure is eliminated before the failure notification cell is inserted. The failure notification cell generation circuit described. While the failure detection means becomes effective when a connection failure is detected, the insertion means provides an initial generation flag that becomes invalid when a failure notification cell is inserted into an empty cell of the main signal cell, and the insertion means eliminates the connection failure. 4. The fault notification cell generation circuit according to claim 3, wherein even if the initial generation flag is valid, the fault notification cell is inserted into an empty cell of the main signal cell. When the common count value is updated several times per second and a connection failure is detected, the common count value at the time of the failure detection is stored, while a predetermined value is added to the stored common count value. A failure notification cell generation method for inserting a failure notification cell into an empty cell of the main signal cell when the common count value matches the common count value. 6. The failure notification cell generation method according to claim 5, wherein the failure notification cell is inserted into an empty cell of the main signal cell as long as the added value matches the current common count value until the connection failure is resolved. . 7. The failure notification according to claim 5, wherein the failure notification cell is inserted into an empty cell of the main signal cell only once even if the connection failure is resolved before the failure notification cell is inserted. Cell generation method. An initial generation flag is provided that becomes valid when a connection failure is detected, but becomes invalid when a failure notification cell is inserted into an empty cell of the main signal cell. Even when the connection failure is resolved, the initial occurrence flag is valid. 8. The failure notification cell generation method according to claim 7, further comprising inserting a failure notification cell into an empty cell of the main signal cell.

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