JPH08256159A - In-apparatus non-instantaneous switching method and apparatus - Google Patents

Abstract

PURPOSE: To perform switching without short break in a device like a cross connect device by preventing the difference in cell sequence between two systems even at the time of system switching due to a fault or the like. CONSTITUTION: Dual signal systems are provided, and signals of two systems are synchronized by respective selecting circuits 3 to select the signal of one system, thereby realizing the switching without short break. If abnormality occurs in one system, selecting circuits of respective systems stop the aquisition of synchronism to select the signal of the normal system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intra-apparatus non-interruptible switching method and apparatus for performing non-interruptive non-interruptible switching within a device such as a cross-conet device.

[0002]

2. Description of the Related Art FIG. 11 shows a general structure of a cross-connect device used in an SDH transmission system. In the figure, 1 is an interface unit with a transmission line, 2 is a multiplexing unit,
Reference numeral 5 is a switch unit, 8 is a separation unit, and 11 is an interface unit with the transmission path. Each of these circuits is duplicated into a 0 system and a 1 system, and a multiplexer 3 and a multiplexer 4 for switching between the 0 system and the 1 system are provided in the multiplexing unit 2.
The switch unit 5 is provided with a selector 6 for switching between 0 system and 1 system, a space switch 7, etc., and the separation unit 8 is provided with a selector 9 for switching between 0 system and 1 system, a demultiplexer 10, etc. 0 in the interface unit 11.
A selector 12 and the like for switching between the system and the system 1 are provided. In this configuration, each selector in each circuit normally selects the input of its own system, and at that time, each selector uses a buffer to perform the 0-system and 1-system synchronous pull-in to obtain two systems. The phases of the signals of are aligned and switched without interruption.

[0003]

FIG. 15 shows a state in which the multiplexer 1 is switched to the 0 system due to a failure of the 1-system interface section 1 or the like. In this case 0
The system selector 3 continues to select cells from the normal system 0 interface unit 1, but the system 1 selector 3 switches from the defective system 1 interface unit 1 to the normal system 0 interface unit 1.

Here, even if the signal from the 1-system is disconnected due to a failure or the like and the synchronization cannot be achieved, each selector 3 of the 0-system and the 1-system uses a buffer to perform the synchronization pull-in. Therefore, when the synchronization pull-in method is different between the 0-system and 1-system selectors 3, fluctuations occur between the cells of the two systems in the output of the 0-system and 1-system selectors 3.

For example, in the example of FIG. 15, the 0-system selector 3
From the 0-system interface section 1 to “A-empty-B-empty-
The cells were input in the order of "C", and as a result of performing the synchronous pull-in with the 1 system that disconnected this, "empty-empty-"
While the cells are output in the order of "A-B-C", the 1-system selector 3 outputs "A-empty-B" from the 0-system interface unit 1.
-The cells are input in the order of "empty-C", and as a result of performing the synchronous pull-in with the 1 system that has disconnected this, the output side has "A-B-C-empty". -The cells are output in the order of "empty". As a result, the order of the 0-system and 1-system cells is different at the input of the latter-stage multiplexer 4, and when the 0-system and 1-system multiplexer 4 multiplexes this with cells from other routes, its output is 0-system. And 1 system will be different. Therefore, the selector 6 in the switch unit 5 in the subsequent stage cannot switch without interruption.

The present invention has been made in view of the above problems, and an object of the present invention is to perform non-instantaneous switching without making the cell order of two systems different even when the systems are switched due to a failure or the like. To do so.

[0007]

FIG. 1 is a view for explaining the outline of the present invention. In order to solve the above-mentioned problems, in the present invention, the signal system is duplicated, and it is possible to select the signal of one system by synchronizing the signals of the two systems by the selection circuit of each system. This is an intra-device non-interruptible switching device in a device that realizes instantaneous disconnection switching, and when an abnormality occurs in one system, the selection circuit of each system stops the synchronization pull-in and selects a normal system signal. There is provided an in-apparatus non-interruptible switching device configured as described above.

When the selection circuits stop the synchronous pull-in at the time of switching the system in this way, the signals on the output side of the selection circuits of the respective systems have the same phase, and therefore, the instantaneous switching can be performed in the subsequent stage.

This uninterruptible switching device in the apparatus is constructed so that when an abnormality occurs in one system, a control signal for notifying the selection circuit of each system is notified via a signal line. can do.

Alternatively, the intra-device non-interruption switching device is configured such that the device transmits in the SDH system on the transmission path and transmits in the device by ATM, and when an abnormality occurs in one system, The selection circuit of each system can be configured so that information for notifying an abnormality is placed in the OAM cell and notified. By doing so, it is possible to eliminate the signal line for notifying the abnormality.

Further, the above-mentioned intra-device non-interruption switching device stops the synchronous pull-in when an abnormality occurs in one of the systems, and the selection circuit of each system uses a buffer for buffering the signal for the synchronous pull-in. The memory can be configured to reset to a predetermined state. By doing so, the states of the buffers of the two systems can be made the same upon system switching, and non-instantaneous switching can be performed.

In addition, in the above-mentioned intra-apparatus non-interruption switching device, when the selection circuits of each system are connected in a plurality of vertical stages, when the selection circuits of the subsequent stage are forcibly switched, the selection circuit of the previous stage is selected. It is possible to realize a non-instantaneous interruption switching in the device by forcibly switching the selection circuit in the subsequent stage after stopping the synchronous pull-in operation in.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. A case where the present invention is applied to a cross-connect device will be described as an embodiment. This cross-connect device is shown in FIG.
It is the same as the one shown in FIG. 1 and there is a confounding between the switch unit 5 and the multiplexing unit 2 and the demultiplexing unit 8.

As shown in FIG. 1, in this cross-connect device, when one-side (here, one-system) interface unit 1 fails, the first-system interface unit 1 is provided in order to realize non-instantaneous switching in the device. 0 for failure of control signal
Notify (failure notification) to the selectors 3 of the systems 1 and 1. As a result, the 0-system and 1-system selectors 3 stop the synchronous pull-in operation,
Each of the 0-system and 1-system selectors simply passes the input normal-side cell as it is. Therefore, the cell order does not differ between the outputs of the 0-system and 1-system selectors 3. As a result, non-instantaneous switching can be performed by the selector 6 in the switch unit 5 in the subsequent stage.

FIG. 12 shows a configuration example of the selector 3 in the multiplexing unit 2. As shown in the figure, 0-system and 1-system FIFO memories (buffers) 21 for absorbing the phase difference of the input user cells, a cell coincidence comparison circuit 23 for detecting cell coincidence from both systems, one of A selector 24 for selecting a system, a synchronous control circuit 22 for controlling these circuits, and the like are included.

The operation in the selector 3 will be described. (1) When the synchronous pull-in operation is started, the F of either system is
The same cell is continuously read from the IFO memory 21 (the same cell is repeatedly read). At this time, cells after that cell are accumulated in the FIFO memory 21 of this system. A cell coincidence comparison circuit 23 compares the cell that is performing the continuous reading with the cell from the FIFO memory 21 of the other system. When the FIFO memory 21 of the system performing the continuous reading becomes full, this time, the FIFO memory 21 of the other system is continuously read to confirm the cell coincidence. This is because it is not known which cell in which system the phase is advanced.

(2) The FIFO memory 21 for continuous reading is alternately switched until a matching cell is found.

(3) When a matching cell is found, synchronous reading from both systems is started from this point.

(4) In the case where a cell of either system is no longer input due to a failure during synchronization pull-in,
The failure information is notified to the synchronization control circuit 22, and continuous reading of the same cell is stopped.

FIG. 2 shows another embodiment of the present invention.
In this embodiment, the single-system (here, 1-system) interface unit 1 is not mounted. In this case, the 1-system interface unit 1 is not mounted in order to realize non-instantaneous switching in the apparatus. To the selector 3 of 0 system and 1 system. By stopping the synchronous pull-in operation of the 0-system and 1-system selectors 3, the cell order of the outputs of the 0-system and 1-system selectors 3 does not differ. As a result, the selector 6 can switch without interruption.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the SDH method is used for transmission on the transmission line,
In the method of transmitting ATM (asynchronous transfer mode) inside the device, an alarm such as LOS (input signal disconnection), LOF (out of frame synchronization), S-AIS, etc. occurred on the transmission path of one system (here 1 system). In this case, since the selector 3 cannot be synchronized, an alarm from the 1-system interface unit 1 to the 0-system,
Notify the 1-system selector 3. 0 system, 1 system selector 3
By stopping the synchronous pull-in operation, the cell order of the outputs of the 0-system and 1-system selectors 3 is not different.
As a result, the selector 6 can switch without interruption.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the SDH method is used for transmission on the transmission line,
In the method of transmitting ATM (asynchronous transfer mode) in the device, MS-SD is used in one-way (here, one-way) transmission path.
If (deterioration of signal error rate) occurs, the selector 3
Since it is not possible to synchronize in
Sends an alarm to the selectors 3 of 0 system and 1 system. 0 series,
By stopping the synchronous pull-in operation of the 1-system selector 3, the cell order of the outputs of the 0-system and 1-system selectors 3 will not be different. As a result, the selector 6 can switch without interruption.

FIG. 5 shows another embodiment of the present invention. In this embodiment, the SDH method is used for transmission on the transmission line,
In the method of transmitting in the device by ATM (asynchronous transfer mode), the pointer (A
SDH occurs when an error occurs in the pointer indicating the beginning of the TM cell.
When the cells in the frame cannot be recognized, the selector 3 cannot synchronize with each other, and the 1-system interface unit 1 notifies the 0-system 1-system selector 3 of the alarm. 0
The system 1 and system 1 selectors 3 stop the synchronous pull-in operation. As a result, the order of cells does not differ between the outputs of the 0-system and 1-system selectors 3, and the selector 6 can switch without interruption.

FIG. 6 shows another embodiment of the present invention. In this embodiment, when transmission using ATM cells is also performed on the transmission line, the HEC is used on one-side (here, one) transmission line.
If an error occurs in the (Header Error Control) field and the cell is discarded, the selector 3 cannot synchronize, so the system 1 interface unit 1 issues an alarm to system 0,
Notify the 1-system selector 3. 0 system, 1 system selector 3
Stops the sync pull-in operation. As a result, the order of cells does not differ between the outputs of the 0-system and 1-system selectors 3, and the selector 6 can switch without interruption.

FIG. 7 shows another embodiment of the present invention. If control signals such as failure information, alarm information and insert information for stopping the synchronous pull-in operation are sent through separate signal lines, the number of signal lines increases. It is sent to the selector 3 of the 1st system.

FIG. 8 shows another embodiment of the present invention. In this embodiment, notification of failure information, alarm information, etc. when the synchronous pull-in operation is stopped is performed by inserting an OAM (maintenance / operation) cell. In this embodiment, the interface section 1 inserts an OAM cell carrying failure information, alarm information and the like. For example, 1-system interface unit 1
Therefore, if this OAM cell does not reach the selectors 3 of the 0 system and 1 system, it is considered that the interface unit 1 of the 1 system has failed or is not mounted, and the selector 3 of the 0 system and 1 system stops the synchronous pull-in operation.

FIG. 13 shows a configuration example of the selector 3 in the embodiment for inserting the OAM such as the failure information. The difference from the selector configuration of FIG.
The OAM cell detection circuit 25 for detecting the AM cell is set to 0 system, 1
It is provided in the system. This OAM cell detection circuit 2
Reference numeral 5 identifies the OAM cell or the user cell from the header of the input cell, detects the OAM cell, identifies the content of the abnormality, and notifies the synchronous control circuit 22 of an alarm. As a result, the synchronization control circuit 22 stops the synchronization pull-in operation.

FIG. 9 shows another embodiment of the present invention. The buffer (FIFO memory) 2 in each of the above-described embodiments
When the instruction to stop the synchronization pull-in is received in the state where cells are accumulated in 1, the buffer is left as it is, and the mode in which synchronization is not taken is entered. In this state, if the power supply of the package on which the one-system (here one system) selector 3 is mounted is once turned off and then turned on again, the buffer 21 of the one-system selector 3 is cleared and emptied, as shown in FIG. As shown in (1), since the states of the buffers 21 of 0 system and 1 system are different, the phase of the cell after multiplexing is different between 0 system and 1 system, and it is not possible to switch the device without instantaneous interruption. Therefore, in the present embodiment, in order to enable the non-instantaneous interruption switching in the apparatus even in such a case, when there is an instruction to stop the synchronization pull-in, the selectors 3 of the 0-system and 1-system both receive the buffer 2 once.
Make 1 empty.

FIG. 10 shows another embodiment of the present invention. Selector 6 according to a command from the control unit of the device
In the case where the forced switching is performed by the control unit, the control unit controls so that the synchronous pull-in operation in the selector 3 is stopped in order to eliminate the factor that causes the fluctuation of the cell, and the forced switching is performed in the selector 6. Configure as follows. By doing so, it is possible to switch without instantaneous interruption in the device.

In the apparatus having the configuration shown in FIG. 11, as in each of the above embodiments, when cell fluctuation occurs in the output of the selector, the cell order after multiplexing is different between 0 system and 1 system, and the selector Since it will not be possible to switch without interruption in 6
If synchronization cannot be established in the selector 3, the selector 3
However, the application of the present invention is not limited to the apparatus having the configuration shown in FIG. For example, even in a device having a configuration in which there is no confounding between the switch unit 5 and the multiplexing unit 2 and the demultiplexing unit 8 as shown in FIG. 14, if the output of the selector 3 causes cell fluctuation, the switch unit 5 Since the cell order of 0-system and 1-system is different at the input, the cell order of 0-system and 1-system will be different even after separation, and it will not be possible to switch without interruption with the selector 6.
Even in the case of the device having such a configuration, the present invention is applied by stopping the synchronization pull-in operation in the selector 3 when the synchronization cannot be established in the selector 3.

[0031]

As described above, according to the present invention, even when the system is switched due to a failure or the like, the cell order of the two systems does not become different, and the non-instantaneous switching can be performed. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a diagram showing another embodiment of the present invention.

FIG. 7 is a diagram showing another embodiment of the present invention.

FIG. 8 is a diagram showing another embodiment of the present invention.

FIG. 9 is a diagram showing another embodiment of the present invention.

FIG. 10 is a diagram showing another embodiment of the present invention.

FIG. 11 is a diagram showing a configuration example of an apparatus to which the present invention is applied.

FIG. 12 is a diagram showing a configuration example of a selector in an apparatus to which the present invention is applied.

FIG. 13 is a diagram showing another configuration example of the selector in the device to which the present invention is applied.

FIG. 14 is a diagram showing another configuration example of an apparatus to which the present invention is applied.

FIG. 15 is a diagram for explaining a conventional problem.

[Explanation of symbols]

 1, 11 Interface Section 2 Multiplexing Section 3, 6, 9, 12 Selector 4 Multiplexer 7 Spatial Switch 8 Separation Section 10 Demultiplexer 21 Phase Difference Absorption FIFO Memory (Buffer) 22 Synchronization Control Circuit 23 Cell Switch Comparison Section 24 Selector 25 OAM Cell Detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Sato Inventor Hiroyuki Sato 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Shinji Ota 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Toshinori Koyanagi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (6)

[Claims] 1. A device in a device in which a signal system is duplicated and a selection circuit of each system realizes non-instantaneous interruption switching by synchronously pulling in signals of the two systems and selecting a signal of one system. This is a method for switching to a non-instantaneous disconnection method, in which if one system fails, the selection circuit of each system stops synchronous pull-in and selects a normal system signal. . 2. A device in a device in which a signal system is duplicated, and a selection circuit of each system realizes non-instantaneous interruption switching by synchronously pulling in signals of the two systems and selecting a signal of one system. This is a switch for switching between non-instantaneous systems, and when the abnormality occurs in one system, the selection circuit of each system is configured to stop the synchronization pull-in and select the signal of a normal system. apparatus. 3. The apparatus according to claim 2, wherein when an abnormality occurs in one of the systems, a control signal for notifying the selection circuit of each system is notified via a signal line. Non-interruption switching device. 4. The device transmits by SDH method on a transmission line,
It is configured such that the inside of the device is transmitted by ATM, and when an abnormality occurs in one of the systems, the selection circuit of each system is configured to notify the abnormality by placing the information in the OAM cell. Item 2. In-device non-instantaneous interruption switching device according to item 2. 5. When stopping the synchronization pull-in when an abnormality occurs in one of the systems, the selection circuit of each system is configured to reset a buffer memory for buffering a signal for the synchronization pull-in to a predetermined state. Item 5. An intra-device non-interruptible switching device according to any one of items 2 to 4. 6. In a configuration in which the selection circuits of each system are connected in a plurality of vertical stages, when the selection circuits on the rear side are forcibly switched, after the synchronous pull-in operation on the selection circuits on the front stage is stopped, The intra-apparatus non-interruption switching apparatus according to any one of claims 2 to 5, wherein the intra-apparatus non-interruption switching is realized by forcibly switching the selection circuit.