JP3398674B2 - Virtual path alarm detection circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention constitutes an ATM network as an asynchronous transfer mode network.
The present invention relates to a TM communication device, and more particularly to a virtual path alarm detection circuit for detecting an alarm of a virtual path.

[0002]

2. Description of the Related Art ATM (As
In a communication device, in order to prevent propagation of a failure, a VP (virtual path) -AIS (Alarm Indication Signal) cell is provided between the occurrence of the failure and the restoration of the failure. Are transmitted downstream of the virtual path at predetermined time intervals such as 1 second intervals. In addition, the terminal that has detected this VP-AIS cell moves in the direction opposite to the direction in which the VP-AIS cell is sent, in the direction of VP-FERF (Far End Receive Fail).
ure) cells are also sent out at predetermined time intervals such as one second intervals.

FIG. 2 shows a VP-A in each ATM communication device.
This is for explaining how the IS cell and the VP-FERF cell are transmitted. In this example, the ATM communication device A and the ATM communication device E arranged at the ends of the five ATM communication devices A to E terminate the virtual path. Now, consider a case where a VP alarm is detected at the detection point 31 of the ATM communication device C. The VP-AIS is detected at the detection point 31 of the ATM communication device C when the upstream virtual path a or b has a failure.

On the other hand, in the VP-FERF cell, when the virtual paths h, g, f, and e in the opposite direction fail, the AT
It is detected at the detection point 31 of the M communication device C. That is,
When the virtual paths h, g, f become a failure, each ATM communication device D, C, B sends out a VP-AIS cell to the downstream side, and the ATM communication device A terminating the virtual path detects this. Then, VP-FERF is added to the virtual path a.
The cell is transmitted, and this is detected at the detection point 31 of the ATM communication device C.

When a VP-AIS cell or VP-FERF cell is detected, a VP-AIS alarm or VP-FE is detected.
An RF alarm is generated. Further, when the detection of these cells is interrupted for a predetermined time longer than the above-mentioned time interval such as 3 seconds, it is detected that the alarm state is restored to the normal state. As described above, conventionally, the virtual path alarm detection circuit has an independent virtual path number timer for each of the AIS alarm and the FERF alarm, and the AIS alarm and the FERF alarm are independently detected.

By the way, ATs handled by ATM communication devices
A virtual path number (VP number) and a virtual channel number (VC number) representing the path or channel of the cell destination are added to the header of the M cell. These VP
The ATM cell is switched in the ATM network and delivered to a desired destination by the number and the VC number. However, there are two types of ATM communication devices, one of which identifies both the VP number and the VC number, and the other of which identifies either one. The ATM communication device dealt with in this specification is designed to identify only a VP number.

[0007]

The number of virtual paths is 1.
There are 4096 per transmission line, which is a large number. For this reason, conventionally, 4096 timers have been required as the number of virtual paths for the AIS alarm and the FERF alarm. That is, in order to detect these two types of alarms, it is necessary to use twice as many timers as 4096 timers.
There was a problem that the circuit scale would increase accordingly.

Therefore, an object of the present invention is to provide AIS alarm and FE.
It is to reduce the circuit scale of a virtual path alarm detection circuit that detects both RF alarms.

[0009]

According to the invention described in claim 1, (a) the information relating to the occurrence of a fault incorporated in the ATM cell transmitted in the asynchronous transfer mode is identified and transferred. Whether the cell is an AIS alarm cell transmitted at a predetermined time interval on the downstream side of the virtual path from the occurrence of a failure in the virtual network to the recovery, or the terminal side receiving this AIS alarm cell is the opposite FERF to be transmitted at a predetermined time interval described above in the direction
Cell identification means for identifying whether the cell is an alarm cell, and (b)
A virtual path number identifying means for identifying the virtual path identification information incorporated in the ATM cell to identify the transferred virtual path number of the cell;
Are prepared one by one corresponding to each virtual path, the AIS alarm cell or FERF alarm cell by cell identification means is reset the count value each time is identified, Cow
If the current value is not reset,
Multiple times of the specified time At least a predetermined time that is at least long
When the count value corresponding to the
Virtual path number identified by the serial number identification means
Is output by the time measuring means for outputting
When the IS alarm cell or the FERF alarm cell is identified, the AIS corresponding to the identified virtual path
When the alarm or FERF alarm is memorized and the time keeping means outputs the virtual path number, the corresponding A
AIS alarm cell and FERF alarm cell in TM cell
About the alarm cell of the one that was not the target of detection
The virtual path alarm detection circuit is equipped with alarm management information storage means for storing that the failure of (1) has been recovered.

That is, in the invention described in claim 1, attention is paid to the fact that the AIS alarm cell and the FERF alarm cell are not simultaneously received on the same virtual path as will be described later, and the clocking means for these is shared. I decided to do it. Also, the timekeeping means is an AIS alarm cell or FER.
Every time the F alarm cell is identified, the count value is reset.
And the count value is not reset
AIS alarm cell or FERF alarm by continuing
When a cell is output during the period from the occurrence of failure to the restoration
Corresponding to a predetermined time that is at least several times longer than
When the count value to be reached is reached, the virtual path number identification
Outputs the virtual path number identified by other means.
And when the virtual pass number is output
Is the AIS alarm cell in the corresponding ATM cell
One of the FERF alarm cells that was not the detection target
Decided to recover from the failure of the alarm cell. In this way, if there are as many clocking means as the number of virtual paths, it is possible to manage the occurrence and restoration of failures for two types of alarms.
It becomes possible to use the clocking means for these two types of alarms.
It is possible to significantly reduce the circuit scale of the virtual path alarm detection circuit as compared with the case where the above are separately prepared.

In the invention described in claim 2, the alarm management information storage means in the invention described in claim 1 is, for example, AI.
AIS that manages S alarm and FERF alarm individually
It was decided to be composed of two types of tables, an alarm management table and a FERF alarm management table.

[0012] In the present invention of claim 3, wherein, when the AIS alarm cell is detected FERF alarm FERF alarm management table is stored to be restored, the FERF alarm cell is detected AIS alarm AIS alarm management table By memorizing the fact that the alarm has been restored, the inconvenience that both alarms are duplicated is eliminated.

In the invention described in claim 4, as an example, the AIS alarm cell or FER in the invention described in claim 1
The F alarm cells are sent out at intervals of 1 second, and the timing means decides to detect that the corresponding fault has recovered when it no longer detects the AIS alarm cell or the FERF alarm cell for at least 3 seconds.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to Examples.

FIG. 1 shows a virtual path alarm detection circuit according to an embodiment of the present invention. The ATM cell 11 is input to the AIS cell identification circuit 12, the FERF cell identification circuit 13 and the VPI (virtual path identifier) identification circuit 14, respectively. Here, the AIS cell identification circuit 12 determines the input information in the ATM cell 11,
If this is an AIS cell, the AIS cell detection signal 15 is output. Similarly, the FERF cell identification circuit 13 discriminates the input information in the ATM cell 11 and outputs the FERF cell detection signal 16 if this is the FERF cell. VP
The I identification circuit 14 outputs the VP number 17, which is the virtual path number of the input ATM cell 11.

The AIS cell detection signal 15 is supplied to the AIS alarm management table 18, the FERF alarm management table 19 and the timer circuit 20. In addition, the FERF cell detection signal 16 also has the AIS alarm management table 18 and F
It is supplied to the ERF alarm management table 19 and the timer circuit 20. Similarly for VP number 17, AIS alarm management table 1
8 and FERF alarm management table 19 and timer circuit 2
Supplied to zero.

The timer circuit 20 has a timer for the number of virtual paths that independently counts the alarm protection time for the number of virtual paths. Here, the alarm protection time means a length of time after the detection of the corresponding AIS cell or FERF cell and when these detections are not performed, it is not considered that the alarm is recovered. In this embodiment, the AIS cell and the FERF cell are received at an interval of 1 second after the occurrence of a failure, and it is considered that the alarm is restored when the AIS cell and the FERF cell are not received for 3 seconds. Therefore, the alarm protection time in this case is 3 seconds. Therefore, the AIS cell identification circuit 12 or FE
When the AIS cell detection signal 15 or the FERF cell detection signal 16 is input from the RF cell identification circuit 13,
The timer count corresponding to the VP number from the VPI identification circuit 14 is started. If the AIS cell detection signal 15 or the FERF cell detection signal 16 of the corresponding VP number 17 is input before the count of the corresponding timer starts and the count value reaches a certain value, the counter of this timer It will be reset and the counting will be started again.

In this way, the count value of the corresponding timer is reset one after another while a failure occurs, so that the state where the above-mentioned constant value is not reached continues. When the failure is recovered and the AIS cell detection signal 15 or the FERF cell detection signal 16 is no longer input, the count value of the timer reaches a predetermined value. In this embodiment, the count value corresponds to 3 seconds. At this point, the timer circuit 20 outputs the corresponding VP number 22. That is, the VP number 22 attached to the header of the ATM cell is output.

The reason why the timer circuit 20 is also used for detecting the AIS cell and the FERF cell is based on the premise that the AIS alarm and the FERF alarm are not simultaneously received in the same virtual path. . As already described with reference to FIG. 2, the AIS cell is a cell sent when the upstream side fails, and the FERF cell is sent from the device that terminates the upstream virtual path when the failure occurs in the opposite direction. It is a cell that comes. Therefore, when a situation occurs in which the upstream and the downstream become obstacles at the same time, the FERF cell is not transferred before the location where the trouble occurs upstream because the upstream is a trouble. In this case,
This is because only the AIS cell can reach the virtual path alarm detection circuit.

By the way, the AIS alarm management table 18 is
When the AIS cell detection signal 15 output from the AIS cell identification circuit 12 is supplied, it is stored in the table as the AIS alarm of the virtual path number corresponding to the VP number 17 output from the VPI identification circuit 14 is generated. When the VP number 22 is input from the timer circuit 20,
It is stored in this table as the AIS alarm of the corresponding virtual path number is restored. As a form of such storage, for example, when an AIS alarm is generated, a signal "1" is written in the storage area of the corresponding virtual path number of the AIS alarm management table 18, and when the AIS alarm is restored, this is signaled. It is possible to return it to 0 ".

The same applies to the FERF alarm management table 19, and the occurrence and restoration of the FERF alarm are stored in this table in association with the virtual path number. In this way, AI as a virtual path alarm
Occurrence and recovery of S alarm and FERF alarm are detected, and monitoring can be performed by these alarm management tables 18 and 19.

In this embodiment, the AIS cell identification circuit 12 is A
In addition to the IS alarm management table 18 and the timer circuit 20, the FE
The one connected to the RF alarm management table 19 is AI.
After the S cell is detected , the timer circuit 20 outputs the VP number 2
2 Ru is output when FERF alarm is order to be restored. Similarly, the FERF cell identification circuit 13
In addition to the alarm management table 19 and the timer circuit 20, the AIS alarm management table 18 is connected to the VP number 22 from the timer circuit 20 after the FERF cell is detected.
When Ru is output AIS alarm is order to be restored.

In this embodiment, one transmission line has 40
Although it has been described that there are 96 virtual paths, the present invention is naturally applicable to a virtual path network in which other numbers of virtual paths exist. Further, in the embodiment, the AIS cell and the FERF cell are described as being transferred at 1 second intervals, but it goes without saying that other time intervals may be used.

[0024]

As described above, according to the first aspect of the invention, the AIS alarm cell and the F
Since the ERF alarm cells will not be received at the same time, we decided to share the timing means for these. Also,
AIS alarm cell or FERF alarm cell is used as the timekeeping means.
Count value is reset each time it is identified
And the state where the count value is not reset continues
As a result, the AIS alarm cell or FERF alarm cell has failed.
Multiple times of the predetermined time output between the occurrence of
At least a long, predetermined amount of time
The virtual path number identification means.
To output the virtual path number identified by
However, when the virtual pass number is output,
AIS alarm cell and FERF alarm in the corresponding ATM cell
The alarm cell that was not the target of detection among the information cells
About the failure was decided to be restored. As a result, two types of clocks can be created by preparing clocking means for the number of virtual paths .
It is possible to manage the occurrence of alarm failures and recovery.
This makes it possible to significantly reduce the circuit scale of the virtual path alarm detection circuit as compared with the case where the timekeeping means is separately prepared for these two types of alarms, and the cost of the circuit can be reduced.

According to the invention of claim 2, the alarm management information storage means in the invention of claim 1 is AI.
AIS that manages S alarm and FERF alarm individually
It was decided to be composed of two types of tables, an alarm management table and a FERF alarm management table. Since the tables to be managed are different as described above, there is an advantage that the management becomes easy.

Further, according to the invention of claim 3, the AIS
When an alarm cell is detected, F is added to the FERF alarm management table.
The fact that the ERF alarm has been restored is stored, and when the FERF alarm cell is detected, the fact that the AIS alarm has been restored is stored in the AIS alarm management table. It has disappeared.

According to the invention of claim 4, the AIS alarm cell or the FERF in the invention of claim 1 is also provided.
The alarm cells are sent out at intervals of 1 second, and the timing means decides to detect that the corresponding fault has been repaired when it no longer detects the AIS alarm cell or the FERF alarm cell for at least 3 seconds. As a result, it is possible to prevent a detection error that the transmission interval of the corresponding alarm cell is shifted for some reason or that the failure is recovered even if the detection cannot be performed once or twice.

[Brief description of drawings]

FIG. 1 is a block diagram of a virtual path alarm detection circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing how VP-AIS cells and VP-FERF cells are transmitted in each ATM communication device.

[Explanation of symbols]

11 ATM cells 12 AIS cell identification circuit 13 FERF cell identification circuit 14 VPI identification circuit 18 AIS alarm management table 19 FERF alarm management table 20 timer circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-338898 (JP, A) JP-A-7-143208 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/24 H04L 12/56 400

Claims (4)

(57) [Claims] 1. Information relating to the occurrence of a failure, which is incorporated in an ATM cell transmitted in asynchronous transfer mode, is identified, and the transferred cell is transferred between the occurrence of the failure and the recovery of the virtual network. Whether it is an AIS alarm cell which is sent to the downstream side of the virtual path at a predetermined time interval, or a terminal which receives this AIS alarm cell is a FERF alarm cell which sends it in the opposite direction at the above predetermined time interval. And a virtual path number identifying means for identifying the transferred virtual path number of the cell by identifying the virtual path specifying information incorporated in the ATM cell. Correspondingly prepared one by one, the cell identification means by the AIS alarm cell or FER
Identifies the F alarm cell reset of the count value each time
The count value is not reset and continues
A predetermined number of times longer than the predetermined time
When the count value corresponding to the time of
Virtual identified by the charpass number identification means
When the cell identification means identifies the AIS alarm cell or the FERF alarm cell by the time counting means for outputting the path number, the AIS alarm or FERF corresponding to the identified virtual path.
Storing the alert occurs, clock means said virtualizer
When the pass number is output, the corresponding ATM cell
Of the detection of the AIS alarm cell and the FERF alarm cell
A virtual path alarm detection circuit comprising alarm management information storage means for storing that the failure of the alarm cell which was not the target is recovered. 2. The alarm management information storage means is the AI.
AIS that manages S alarm and FERF alarm individually
The virtual path alarm detection circuit according to claim 1, comprising an alarm management table and a FERF alarm management table. 3. FE when the AIS alarm cell is detected
The fact that the FERF alarm is restored is stored in the RF alarm management table, and when the FERF alarm cell is detected, the AIS is detected.
3. The virtual path alarm detection circuit according to claim 2, wherein the alarm management table stores that the AIS alarm has been recovered. 4. The AIS alarm cell or the FERF alarm cell is sent out at an interval of 1 second, and when the time measuring means stops detecting the AIS alarm cell or the FERF alarm cell for at least 3 seconds, the corresponding failure is recovered. The virtual path alarm detection circuit according to claim 1, wherein the virtual path alarm detection circuit detects the fact.