JPH04337935A - Data switching system - Google Patents

Abstract

PURPOSE:To execute switching without fail between data cells of active and auxiliary systems by inserting a switching flag cell into the data cell. CONSTITUTION:The same data cells always flow to the active and auxiliary system and the data cell of the active system is selected and outputted normally. Cell insertion parts 1 and 2 for active system and auxiliary system are provided to insert the switching flag cells to the respective data cells of the active and auxiliary systems, and a switching part 3 is provided to input the data cells outputted from the cell insertion parts 1 and 2, to switch the system to the auxiliary system and to output the data cell after the switching flag cell of the auxiliary system when the switching flag cell in the data cell of the active system is detected. When the switching flag cell in the data cell of the auxiliary system is detected, the system is switched back to the active system. Namely, since the data cell is selectively outputted with the switching flag as the border, switching is enabled without being interrupted, and wrong switching can be prevented.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a data switching system, and more particularly to a data switching system in which the same data cells are always flowing in the active system and the backup system, and normally cells in the active system are selected for output. be.

[0002] Recently, ATM (Asynchronous Trans
(fer Mode: asynchronous transfer technology) Network research is being actively conducted, and this ATM network consists of a header part (5 bytes) and a payload part (48 bytes).
STM (Synchronous
Transfer Mode: Synchronous Transfer Technology) Compared to a network, time slot allocation processing is unnecessary, so it is suitable for distributed processing control and enables highly flexible multiplex transmission.

[0003] In such a network, since the processing of data cells is complicated, it is necessary to always ensure the safety of data cells.

0004

2. Description of the Related Art In order to ensure the safety of data cells, a system has already been proposed in which the data cell transmission line or device is a dual system of a working system and a standby system, and the same data cells are always transmitted.

In such a duplex system, cells of the working system are normally selected for transmission, but when a failure occurs in the working system, it is necessary to switch to the protection system.

[0006] As such a switching system between the active system and the standby system, the one shown in Japanese Patent Laid-Open No. 1-86348 is known, and in this system, switching means is provided in both the transmitting device and the receiving device. , at the time of switching, data cells are transmitted in parallel from the transmitting device to both the working transmission path and the protection transmission path, and the receiving device temporarily stores the data cells from both transmission paths in respective buffers, and The amount of delay in both buffers is adjusted so that the bits of the data cells output from the two buffers match, and when they match, the switching means executes switching between the working system and the backup system.

[0007]

[Problem to be Solved by the Invention] In such a conventional data switching system, whether each bit of a data cell is the same cell is determined based on whether or not they match.
If the data cells happen to match, erroneous switching may occur.

[0008] Furthermore, in such a system, empty cells in which all the bits in the data cell are "0" are frequently mixed in, so it is necessary to check the coincidence/mismatch of each bit as described above. If this happens, there is a problem in that a match between empty cells will be detected and the same erroneous switching will be performed.

[0009] Therefore, the present invention is capable of transferring data between the working system and the protection system without error in a data switching system in which the same data cells always flow in the working system and the protection system, and normally cells in the working system are selected and output. The purpose is to realize a data switching method that performs switching.

0010

[Means for Solving the Problems] In order to solve the above problems, in the data switching system according to the present invention, as shown in principle in FIG. A cell insertion unit 1, a protection cell insertion unit 2 that inserts a switching flag cell into a data cell of the protection system, and data cells output from both cell insertion units 1 and 2 are input, and data cells in the data cells of the working system are inputted. The switching unit 3 includes a switching unit 3 that switches to the standby system when a switch flag cell is detected and outputs data cells subsequent to the switch flag cell of the standby system.

Further, in the present invention, when the switching unit 3 detects a switching flag cell in the data cell of the protection system after switching from the working data cell to the protection data cell, the switching unit 3 switches the switching unit 3 back to the working system. Data cells subsequent to the switching flag cell of the active system can be output.

0012

[Operation] In the present invention shown in FIG. 1, the working data cell and the protection data cell are input to the working cell insertion section 1 and the protection cell insertion section 2, respectively, but under normal conditions when no failure occurs, switching is performed. The data cell is sent to the switching unit 3 as a data cell that does not include any flag cell F, but under normal conditions, the switching unit 3 selects and outputs the currently used data cell.

On the other hand, when a failure occurs and it becomes necessary to switch from the active system to the standby system, the switching flag cell F
is commonly given to the active cell insertion section 1 and the protection cell insertion section 2.

As a result, as shown in FIGS. 2 and 3, the switching unit 3 is provided with the working data cell and the protection data cell in which the switching flag cell F is inserted between the data cells Become.

[0015] Here, when the working data cell and the backup data cell are input to the respective cell insertion sections 1 and 2, the same cells are input at the same time, but for some reason, In the case of FIG. 2, the active system may be faster than the backup system, and in the case of FIG. 3, the active system may be slower than the backup system.

FIG. 2(a) shows a normal state in which a working data cell is selected. In this state, the switching unit 3 detects the switching flag cell F inserted into the working data cell. At this time, the switching unit 3 is switched as shown in FIG. 2(b).

After detecting the switching flag cell F among the backup data cells that have arrived late, the switching section 3 outputs the subsequent backup data cells (1) to (4). At this time, there will be two empty cells among the data cells output from the switching unit 3, but the actual data will be output without interruption.

Furthermore, in FIG. 3(a), the switching section 3
After selecting the active system data cells ■ to ■, it detects the switching flag cell F, but at this time, the protection system data cells ■ to ■, the switching flag cell F, and the data cell ■ have already been input to the switching unit 3. Therefore, the switching section 3 selects and outputs only the data cells 1 to 2 after the switching flag cell F among the backup data cells, as shown in FIG. At this time, uninterrupted switching is performed without any vacant cells.

In this manner, in both cases of FIGS. 2 and 3, switching between the active system and the backup system can be performed without error and without momentary interruption.

[0020]

[Embodiment] FIG. 4 shows an embodiment of the working cell insertion unit 1 or protection cell insertion unit 2 used in the data switching system according to the present invention shown in FIG. 11, a control unit 12, and a selector 13. After a working or backup data cell is input to the buffer 11 and stored once, it is output through the selector 13.

On the other hand, a failure occurs and the switching signal is sent to the control unit 1.
2, the control section 12 temporarily stops the output of data cells 1 to 2 of the buffer 11, generates a switching flag cell F, and sends it to the selector 13. Also, at this time, the control unit 12 causes the selector 13 to switch to the switching flag cell F.
Since the control is performed so that the data cells 1 to 2 are selected, the selector 13 outputs the switching flag cell F after the data cells 1 to 2, as shown in the figure.

After that, the control unit 12 causes the buffer 11 to output the subsequent data cells
3 to the buffer 11 side, and data cells ■,■
...output as follows.

FIG. 5 shows an embodiment of the switching unit 3 used in the data switching system according to the present invention shown in FIG. 21, a detection unit 22 for detecting the switching flag cell F inserted into the protection data cell, a buffer 23 for temporarily storing the working data cell, a buffer 24 for temporarily storing the protection data cell, and a buffer 23
and a selector 25 that selects and outputs each of the 24 output signals.
The buffers 23 and 24 are controlled according to the detection signals from the switching flag cell detection units 21 and 22, and the selector 2
5, and a control section 26 that controls the 5.

In such a switching unit 3, first, when a switching flag cell F is inserted in the active data cell, the detecting unit 21 detects this switching flag cell F and notifies the control unit 26, and then the control unit 26 detects the switching flag cell F. The unit 26 controls not to output any subsequent active data cells from the buffer 23 and controls the selector 25 to switch from the buffer 23 to the buffer 24 side.

On the other hand, although the backup data cell is normally not output from the buffer 24, the switching flag cell F inserted into the backup data cell is detected by the detection unit 22.
, the selector is switched to the buffer 24 side by controlling the buffer 24 and controlling the selector 26 to output the backup data cells after the time when the switching flag cell F is detected. A spare data cell is selected from 25 and output.

[0026] The above cell insertion units 1 and 2 are, for example, A
This corresponds to an interface section in the TM cross-connect device, and the switching section 3 similarly corresponds to a multiplexing (MUX) section.

Further, in the above embodiment, switching from a working system data cell to a protection system data cell has been discussed, but the invention is not limited to this, and the control unit 26 can recognize whether it is a working system or a protection system. By doing this, it is also possible to switch from the backup system to the active system.

[0028]

As explained above, in the data switching method according to the present invention, when switching a data cell from a working system to a protection system, a switching flag cell is inserted into the data cell, and switching is performed using this switching flag cell as a boundary. In the previous system, the data cells before this switching flag cell were selected, and in the system after switching, only the data cells after that switching flag cell were selected and output, so switching can be performed without momentary interruption, and the switching flag cell can be By configuring it with special bits, erroneous switching will not occur, and the problem of empty cells with all "0" will be solved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the principle of the configuration of a data switching system according to the present invention.

FIG. 2 is a diagram for theoretically explaining the operation of the data switching system according to the present invention (when the active system is faster than the backup system).

FIG. 3 is a diagram for theoretically explaining the operation of the data switching system according to the present invention (when the active system is slower than the backup system).

FIG. 4 is a block diagram showing an embodiment of a cell insertion section used in the data switching method according to the present invention.

FIG. 5 is a block diagram showing an embodiment of a switching section used in the data switching method according to the present invention.

[Explanation of symbols]

1 Active cell insertion part 2 Reserve system cell insertion part 3 Switching section In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] Claim 1: In a data switching method in which the same data cells are always flowing in the working system and the protection system, and normally the cells in the working system are selected and output, the working system inserts a switching flag cell into the data cell in the working system. A cell insertion section (1), a protection cell insertion section (2) that inserts a switching flag cell into a protection data cell, and both cell insertion sections (1, 2) are input, and the data cells output from the cell insertion section (1, 2) are inserted into the current cell. A data switching system comprising: a switching unit (3) for switching to the backup system when detecting a switching flag cell among the data cells of the backup system and outputting data cells subsequent to the switching flag cell of the backup system. 2. When the switching unit (3) detects a switching flag cell in the data cell of the protection system after switching from the working data cell to the protection data cell, the switching unit (3) switches the switching unit back to the working system. 2. The data switching method according to claim 1, wherein data cells subsequent to a system switching flag cell are output.