JP2647003B2 - ATM switch system switching control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM having a redundant configuration.
(Asynchronous Transfer Mo
de; asynchronous transfer mode).

[0002]

2. Description of the Related Art Conventionally, there are the following three systems for switching systems in an ATM switch having two systems, an active system and a standby system. That is, in the case of the first method, a buffer is provided inside the ATM switch, and a detecting means for detecting that the buffer is empty is provided. First, the input side of the ATM switch is switched from the old working system (working system) to the new working system (standby system), and new cells are sequentially accumulated in the new working system buffer. Thereafter, when the cells stored in the old working system are output from the buffer of the old working system and become empty, the output side of the ATM switch is switched from the old working system to the new working system, and the switching of the system is completed.

[0003] Next, the second method is to use ATM at the time of system switching.
Switch the input side of the switch to the new working system first,
Enter a special cell in the old working system. When the special cell is detected on the output side of the old working system, it is determined that the residual cell of the old working system has disappeared, and the output side is switched to the new working system. In the case of the third system, a counter for counting the number of input cells and a counter for counting the number of output cells are provided on the input side and the output side of each of the active and standby ATM switches. Then, the input side is first switched from the working system (old working system) to the standby system (new working system). In this case, if the counter value on the input side matches the counter value on the output side in the old working system, the output side is switched to the new working system on the assumption that there are no residual cells in the old working system.

[0004]

SUMMARY OF THE INVENTION
The third system switching method is a method in which the input side is switched first and the new cells are stored in the new working system while the remaining cells of the old working system are output, so that the following problems occur. Occurs. That is, the system switching time varies depending on the amount of cells stored in the old active system, and the switching time cannot be constant.

When there are many residual cells in the old working system, the time required to output all the cells becomes long.
If each cell sequentially accumulated in the new active system is concentrated at a certain output port, the buffer for the output port may overflow and the cells may be discarded. Also, AT
At the time of system switching when the M switch fails, not all the residual cells of the old working system are always output normally.
There is a disadvantage that the reliability of the system is reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problem by quickly switching the system of the ATM switch having the working system and the standby system.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an active ATM switch and a standby ATM switch each having a buffer therein and performing a switching process by inputting cells. When performing the system switching control between the ATM switches, the operating AT is input to the input unit on the input side of each ATM switch.
Input to the M switch and not output to the buffer
A memory is provided in which the remaining cells are stored together with their identification information in the order of input, and a cell output from the operating ATM switch at the time of system switching of the ATM switch is checked.
Provided with an output cell confirmation unit for transmitting the identification information of the cell to the input portion to the output side of the ATM switch, the ATM
A system switching control means for simultaneously switching the input side and the output side of the switch; and identification information matching when identification information from the output cell confirmation unit provided in the input unit matches identification information of a cell stored in the memory. And a memory control unit that deletes, from the memory, the cells and the corresponding identification information that have been stored before storing the cells and the identification information. The system switching control means clears the buffer of the operating ATM switch at the time of system switching of the ATM switch and discards the remaining cells in the buffer.

[0008]

In the memory on the input side of each ATM switch, cells input to the operating ATM switch and not output are stored together with their identification information in the order of input, and system switching for simultaneously switching the input side and the output side of the ATM switch is performed. Then, the cell in the memory that matches the identification information of the cell output from the ATM switch and the cell already stored before the storage of this cell are deleted from the memory, and the switched ATM switch stores the cell in the memory. The oldest cells are entered in order. As a result, it is possible to quickly and reliably switch the system of the ATM switch having the active system and the standby system. In addition, at the time of system switching of the ATM switch, the residual cells in the ATM switch that have been operating up to now are discarded. As a result, it is possible to prevent a residual cell from being output at the time of system switching again.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.
In FIG. 1, reference numerals 1A and 1B denote active and standby ATM switches, respectively. A system selector 2 is provided in a stage preceding the duplexed ATM switches 1A and 1B, and a system selector 3 is provided in a stage subsequent thereto. Further, a switch input unit 4 is provided at a stage preceding the system selection unit 2, and an input cell buffer 5 is provided in the switch input unit 4.

The input cell buffer 5 includes a switch transmission standby cell buffer 51 (hereinafter, buffer 51) and a switch transmission completed cell buffer 52 (hereinafter, buffer 5).
2) and an empty buffer 53 (hereinafter, buffer 53). The buffer 51 accumulates cells that are not sent to the ATM switch and are in a standby state. The buffer 52 accumulates cells that have been sent to the ATM switch but have not been notified from the output side of the ATM switch that the output has been completed. Also,
The buffer 53 is an empty buffer that is opened to store cells.

The total capacity of the buffers 51 to 53 is constant, but the capacity of each buffer changes according to the input / output of cells. Each of the buffers 51 to 5
In 3, not only the cell output to the ATM switch but also its identification information are stored at the same time. The control of each of the buffers 51 to 53 is controlled by an input cell buffer control signal h from an input cell buffer control unit 6 provided in the switch input unit 4. In addition, each A to which a cell is input
The input side and the output side of the TM switches 1A and 1B are selected by the above-described system selection units 2 and 3, respectively, and each of the system selection units 2 and 3 performs a selection operation according to an instruction of the system switching instruction unit 7. On the output side of the system selection unit 3, an output cell check unit 8 for checking cells output from the ATM switch is provided.

Next, the operation of the ATM switch system configured as described above will be described. First, the operation in the normal state where the ATM switch is not switched will be described. In the normal state, when the cell enters the switch input unit 4,
An open buffer area is secured from the buffer 53 and stored in the buffer 51. Then, the cells sequentially stored in the buffer 51 are read out from the oldest storage, output to the active ATM switch 1A via the system selection unit 2, and stored in the buffer 52. At this time, the buffer size (capacity) of the buffer 51 decreases by one cell, and conversely, the size of the buffer 52 increases by one cell.

In the active ATM switch 1A, the cell output from the system selector 2 is inputted, exchanged, and output to a predetermined output line (not shown). The cells output in this way are sent to the next processing unit via the system selection unit 3. Here, the output cell confirmation unit 8 described above is provided on the output side of the system selection unit 3, and the output cell confirmation unit 9
Confirms cells output at time intervals during which the buffer 51 of the switch input unit 4 does not overflow. And
The identification information of the cell indicating which cell has been output is put on the reception notification signal a and transmitted to the input cell buffer control unit 6 in the switch input unit 4.

In this case, the input cell buffer control unit 6 receives the cell reception notification signal a, decodes the contents thereof, and stores the previously stored cells including the corresponding cells and their identification information in the buffer 52. , And the buffer area in which the cell has been stored is released and added to the buffer 53. As described above, in the normal state, the switch input unit 4 always outputs the cell output to the ATM switch to the AT switch.
It is temporarily held until output from the M switch.

Next, the operation of the ATM switch system when the ATM switch is switched will be described. At the time of system switching, the system switching instruction unit 7 described above
First, the input cell buffer control unit 6 of the switch input unit 4
Outputs a cell output stop request signal b. The input cell buffer control unit 6 receiving the cell output stop request signal b
Controls the incoming cells to be stored in the buffer 51 as usual, but stops sending cells to the ATM switch 1A and outputs a cell output stop report signal c to the system switching instruction unit 7. .

In response to the reception of the cell output stop report signal c, the system switching instructing unit 7 sends a system selection signal d to the system selecting units 2 and 3 so that the active ATM switch 1A transmits the standby ATM switch 1A. Execute system switching to the switch 1B,
Further, a buffer clear signal e is output and cleared in order to discard all cells stored in a buffer (not shown) in the ATM switch 1A of the working system (old working system). Further, it outputs a cell confirmation request signal f to the output cell confirmation section 8.

In this case, the output cell confirming section 8 transmits the latest identification information of the output cell to the input cell buffer control section 6 on the cell reception notification signal a, and at this time, the switching display signal Also transmits g. As a result, the input cell buffer control unit 6 determines that the output cell is in the process of switching the system, decodes the received cell reception notification signal a, and stores the corresponding cell and the previously stored cell including the identification information. Then, all the identification information is erased from the buffer 52, and the buffer area storing these cells is released and added to the buffer 53.

Note that the input cell buffer control unit 6 controls so that cells from the buffer 51 are always output. In this case, the new active ATM cells are stored in the buffer 52 sequentially from the oldest cell. Control is performed so as to output to switch 1B. Thereafter, the input cell buffer control unit 6 makes the cell output stop report signal c output to the system switching instruction unit 7 non-output, and cancels the cell output stop report. As a result, the system switching instructing unit 7 cancels this request by setting the cell output stop request signal b being output to the input cell buffer control unit 6 to no output, and cancels the cell confirmation request signal f being output to the output cell checking unit 8. Withdraw this request as no output. Then, at this time, the output cell confirmation unit 8 makes the switching display signal g being output to the input cell buffer control unit 6 non-output and cancels the switching display. Thus, a series of switching sequences is completed.

As described above, in the present system, the change in the system switching execution time due to the amount of stored cells is suppressed in comparison with the conventional system in which all the cells stored in the active system are switched after the system is switched. It is possible to switch the system at a high speed with a certain minimum time, and thus it is possible to improve the reliability of the system.

[0020]

As described above, according to the present invention, the cells which are input to the operating ATM switch and which are not output are stored in the memory on the input side of each ATM switch together with the identification information thereof in the order of input, and the ATM switch has When system switching is performed to switch the input side and output side simultaneously, AT
The cell in the memory that matches the identification information of the cell output from the M switch and the cell already stored before the storage of this cell are deleted from the memory, and the switched ATM switch deletes the cell stored in the memory. Since the input is performed in order from the old cell, the AT having the working system and the standby system is used.
Switching of the system of the M switch can be performed quickly and reliably. Further, at the time of system switching of the ATM switch, the residual cells in the ATM switch which have been operated up to now are discarded, so that output of the residual cells at the time of system switching again can be prevented.

[Brief description of the drawings]

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

[Explanation of symbols]

1A, 1B ... ATM switch, 2,3 ... System selection unit, 4 ...
Switch input unit, 5: input cell buffer, 6: input cell buffer control unit, 7: system switching instruction unit, 8: output cell confirmation unit, 51: switch transmission standby cell buffer, 52: switch transmitted cell buffer, 53 ... Free buffer, a ...
Cell reception notification signal, b: Cell output stop request signal, c: Cell output stop report signal, d: System selection signal, e: Buffer clear signal, f: Cell confirmation request signal, g: Switching display signal.

Claims (2)

(57) [Claims] An ATM switch which includes a working ATM switch which has a buffer therein and performs a switching process by inputting a cell and a standby ATM switch which is in a standby state, and which controls switching between the ATM switches. In the system switching control method, the input section on the input side of each ATM switch is input to the operating ATM switch and is not output, and
A memory is provided in which the cells remaining in the memory are stored together with their identification information in the order of input, and at the output side of each ATM switch, the cell output from the operating ATM switch at the time of switching the system of the ATM switch is checked. The identity of this cell
Provided with an output cell confirmation unit for transmitting the multicast to the entering force unit, the identification from the simultaneous switching system switching control means input and output sides of each ATM switch, it is disposed in the input portion and the output cell check unit When the information matches the identification information of the cell stored in the memory, the cell and the identification information with the matching identification information, the cell already stored before the storage of the cell, and the corresponding identification information are deleted from the memory. A system switching control method for an ATM switch, characterized in that a memory control unit is provided, and the ATM switch switched during the system switching is sequentially input from the oldest cells stored in the memory. 2. The system switching control method for an ATM switch according to claim 1, wherein said system switching control means clears said buffer of an operating ATM switch at the time of system switching of said ATM switch, and removes residual cells in said buffer. A characterized by discarding
System switching control method for TM switch.