JP2000022693A - Atm cross-connection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ATM cross-connection device capable of changeover without a hit even when a data error or the like is generated. SOLUTION: A data contents comparison circuit 24 discriminates whether or not cells inputted to an active system switch 10 and a standby system switch 20 are the same. At the time of discriminating that they are different, a write control circuit 26 makes a cell resident number detection circuit 23 perform control so as not to count the pertinent cell as a resident cell and makes a buffer 22 perform the control so as not to store the pertinent cell. Also, when T cell detection circuits 11 and 21 detect a T cell, the cell resident number detection circuits 13 and 23 detect the numbers of the cells stored in the buffers 12 and 22 and a difference calculation circuit 26 compares the numbers of the cells. A read control circuit 27 stops read for the difference number of the cells when the difference calculation circuit 26 discriminates that the number of cells of the cell resident number detection circuit 13 is larger, or it makes the buffer 22 to perform feed forward for the difference number of the cells at the time of discriminating that the number of cells of the cell resident number detection circuit 13 is smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM cross-connect device in which a redundant configuration is formed by ATM switches, and more particularly to an ATM cross-connect device that switches ATM switches without interruption.

[0002]

2. Description of the Related Art ATM (Asynchronous Transfer Mode):
Asynchronous transfer mode) A in which a redundant configuration is formed by switches
In the TM cross-connect device, it is desirable that the switching of the ATM switch can be performed without instantaneous interruption.

For example, Japanese Patent Laid-Open Publication No. Hei 8-139726 discloses a branch circuit 101 for outputting input data (input cells) to a working switch 110 and a standby switch 120 as shown in FIG. The switching timing cell (T cell) for instructing the selection circuit 103 to perform switching is supplied from the T-cell insertion circuit 102 that outputs the switching timing cell (T cell) to the branch circuit 101 at an arbitrary cycle, and either the working switch 110 or the protection switch 120. An ATM switch system is described which includes a selection circuit 103 which receives cells by switching cells using T cells and outputs the received cells to the outside.

The active system switch 110 includes a T cell detection circuit 111 for detecting that a T cell has been input, a buffer 112 for temporarily storing the input cell, and a T cell detection circuit 111 when the T cell detection circuit 111 detects a T cell. Cell count detection circuit 1 for detecting the number of cells stored in buffer 112
13 is comprised.

[0005] The standby system switch 120 includes a T cell detection circuit 121 for detecting that a T cell has been input, a buffer 122 for temporarily storing the input cell, and when the T cell detection circuit 121 detects a T cell. Cell count detection circuit 1 for detecting the number of cells stored in buffer 122
23 and a difference calculation circuit 126 for comparing the number of cells detected by the cell retention number detection circuits 113 and 123 to calculate a difference.
And a read control circuit 127 that controls the output of the buffer 122 according to the difference calculated by the difference calculation circuit 126.

The buffer 112 of the active switch 110 and the buffer 122 of the standby switch 120 are connected to the branch circuit 1.
01 is temporarily stored.

When the branch circuit 101 detects a T cell in the cells output to the working switch 110 and the protection switch 120, the T cell detection circuits 111 and 121
A signal notifying that the T cell has been detected is transmitted to the cell retention number detection circuits 113 and 123.

When a signal indicating that a T cell has been detected is received from the T cell detection circuit 111, the cell retention number detection circuit 113 detects the number of cells stored in the buffer 112, and calculates a difference calculation circuit. Notify 126.

When a signal indicating that a T cell has been detected is received from the T cell detection circuit 121, the cell retention number detection circuit 123 detects the number of cells stored in the buffer 122, and calculates a difference calculation circuit. Notify 126.

The difference calculation circuit 126 calculates a difference between the number of cells supplied from the cell staying number detection circuits 113 and 123, and notifies the read control circuit 127 of the number of cells corresponding to the difference.

The read control circuit 127 includes the difference calculation circuit 12
The output of the cell stored in the buffer 122 is controlled in accordance with the number of cells corresponding to the difference notified from No. 6.

For example, when the read control circuit 127 receives from the difference calculation circuit 126 a signal notifying that “the number of cells supplied from the cell retention number detection circuit 123 is smaller by one cell”, the buffer 122 The output of one cell corresponding to the difference is stopped among the cells stored by. When the discrimination read control circuit 127 receives a signal from the difference calculation circuit 126 indicating that “the number of cells supplied from the cell retention number detection circuit 123 is larger by one cell”, the buffer 122 stores the signal. Of the cells being moved, one cell corresponding to the difference is advanced.

On the other hand, when the number of cells corresponding to the difference calculated by the difference calculation circuit 126 is 0, the difference calculation circuit 126
Transmits a signal notifying that the number of cells is the same to the read control circuit 127. As the cells stored in the buffers 112 and 122, for example, as shown in FIG. 8A, when the buffer 112 stores a cell A and a cell B and the buffer 122 stores a cell A and a cell B. In addition, the selection circuit 103 can perform the switching operation from the active switch 110 to the standby switch 120 without an instantaneous interruption.

[0014]

However, the branch circuit 10
1 outputs an input cell to the active switch 110 and the standby switch 120, a data error or the like occurs, and the buffer 112 stores the cell A and the cell B as shown in FIG.
It is assumed that the buffer 122 stores the cell A and the cell C. At this time, since the cells stored in the buffers 112 and 122 are different, it is actually impossible for the selection circuit 103 to perform the switching operation from the active switch 110 to the standby switch 120 without instantaneous interruption. .

The present invention has been made in view of the above circumstances, and has as its object to provide an ATM cross-connect device capable of instantaneous interruption switching.

[0016]

In order to achieve the above object, an ATM cross-connect device according to a first aspect of the present invention comprises a branch circuit for branching an input cell to a working switch and a protection switch; A system switch and an insertion circuit for inserting an instruction cell for instructing switching of the standby system switch into the input cell, and connected to the active system switch and the standby system switch, from the active system switch and the standby system switch. Output means for switching from the working switch to the protection switch and outputting the supplied cell to the outside when the designated cell is detected from the supplied cells. And a first buffer that stores the input cell and outputs the stored cell to the selection circuit. First detecting means for detecting said that the instruction cells is input to the developing for system switch, the first
When the detecting means detects the indicated cell,
And a first cell staying number detecting means for detecting the number of cells stored in the buffer of the buffer, wherein the standby system switch stores the input cell and outputs the stored cell to the selection circuit. A second buffer for determining whether or not cells input to the working switch and the standby switch are the same; and a second buffer for determining that the cells input to the working switch and the standby switch are not the same. Control means for controlling not to store a cell corresponding to the above, a second detection means for detecting that the designated cell has been input to the standby switch, and the second detecting means has detected the designated cell. A second cell retention number detection means for detecting the number of cells stored in the second buffer, and a comparison means for comparing the number of cells detected by the first and second cell retention number detection means. , The ratio As a result of comparison by the means, when it is determined that the number of cells detected by the second cell staying number detecting means is smaller, the number of cells stored in the second buffer by the number of cells corresponding to the difference is determined. Means for stopping reading,
Means for delaying the reading of the cells stored in the second buffer by the number of cells corresponding to the difference when the second cell staying number detecting means determines that the number of cells detected is larger; And indicating means having the following.

With this configuration, it is possible to prevent the buffer from storing a different cell due to a transmission line error or the like after input to the working system and the protection system switch. Therefore, switching from the active system switch to the standby system switch can be performed without interruption.

The control means controls the second cell staying number detection means so that the corresponding cell is not counted as a cell stored in the buffer when the determination means determines that the cells are not the same. May be provided.

An ATM according to a second aspect of the present invention.
The cross-connect device includes a branching unit that supplies an input cell to the active switch and the standby switch, an active buffer that stores the input cell from the branching unit and outputs the stored cell, and a branching unit that outputs the stored cell. A standby buffer for storing the input cells and outputting the stored cells; determining means for determining whether the cells input to the active switch and the standby switch are the same; and the determining means And control means for controlling not to store the corresponding cell in the spare buffer when it is determined that the cells are not the same.

Further, the cross-connect device includes a detecting means for detecting that an instruction cell is input to the working switch and the protection switch, and a buffer for the working and protection buffers responding to the detection by the detecting means. When the number of cells stored is detected and compared, and it is determined that the number of cells stored in the standby buffer is smaller than the number of cells stored in the working buffer, the standby buffer is replaced by the number of cells corresponding to the difference. When the reading of the cells stored in the system buffer is stopped, and it is determined that the number of cells stored in the spare buffer is larger than the number of cells stored in the working buffer, only the number of cells corresponding to the difference is determined. Means for postponing the reading of the cell stored in the spare buffer.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ATM cross-connect device according to an embodiment of the present invention will be described.

As shown in FIG. 1, the ATM cross-connect device according to the embodiment of the present invention comprises a branch circuit 1, a T cell insertion circuit 2, a selection circuit 3, a working switch 10, and a protection switch 20. And

The branch circuit 1 outputs an input cell to the connected active switch 10 and standby switch 20.

The T cell insertion circuit 2 inserts a switching timing cell (T cell) for instructing the selection circuit 3 to perform switching at an arbitrary cycle into an input cell.

The selection circuit 3 receives a cell supplied from one of the buffer 12 of the active switch 10 and the buffer 22 of the standby switch 20 by switching it with a T cell, and outputs it to the outside.

The active system switch 10 includes the T cell detection circuit 1
1, a buffer 12, and a cell retention number detection circuit 13.

The T cell detection circuit 11 is provided with the active switch 1
The T cell input to 0 is detected.

The buffer 12 temporarily stores cells input to the active switch 10.

The cell retention number detection circuit 13 detects the number of cells stored in the buffer 12 when the T cell detection circuit 11 detects a T cell.

The standby system switch 20 includes the T cell detection circuit 2
1, a buffer 22, a cell retention number detection circuit 23, a data content comparison circuit 24, a write control circuit 25, a difference calculation circuit 26, and a read control circuit 27.

The T cell detection circuit 21 is provided with a standby switch 2
It detects the T cell input to 0 and outputs a detection signal.

The buffer 22 temporarily stores cells input to the standby switch 20.

The cell retention number detection circuit 23 detects the number of cells stored in the buffer 22 in response to the T cell detection signal and a mismatch signal from a data content comparison circuit 24 described later.

The data content comparing circuit 24 determines whether or not the cells input to the active switch 10 and the standby switch 20 have the same content. Output to the number detection circuit 23 and the write control circuit 25.

In response to the mismatch signal, the write control circuit 25 controls the buffer 22 so that the data content comparison circuit 24 does not store a cell determined to be a different cell.

The difference calculation circuit 26 calculates the difference between the number of cells supplied from the cell retention number detection circuits 13 and 23, and notifies the read control circuit 27 of a signal indicating the difference.

The read control circuit 27 controls the buffer 2 according to the number of cells corresponding to the difference notified from the difference calculation circuit 26.
2 controls the output of the stored cell. That is, when the read control circuit 27 receives a signal notifying that “the number of cells detected by the cell retention number detection circuit 23 is smaller than the cell retention number detection circuit 13” from the difference calculation circuit 26,
Reading of the cells stored in the buffer 22 by the number of cells corresponding to the difference is stopped. Also, the read control circuit 27
When a signal notifying that “the number of cells detected by the cell retention number detection circuit 23 is greater than the cell retention number detection circuit 13” is received from the difference calculation circuit 26, only the number of cells corresponding to the difference is received. The cell stored in the buffer 22 is advanced. Here, the cells to be advanced may be transmitted to the selection circuit 3, or the cells to be advanced may be output without being transmitted to the selection circuit 3.

Next, the operation of the ATM cross-connect device having the above configuration will be described with reference to FIGS.

FIG. 2 is a diagram for explaining the operation of the standby switch 20 when a cell is input, and FIG.
FIG. 9 is a diagram for explaining the operation of the standby switch 20 when a cell is input. 2 and 3 are for facilitating the understanding of the operation, and the processing is not performed in the order of this flow.

The branch circuit 1 sequentially outputs input cells to the active switch 10 and the standby switch 20, and the cells supplied to the active switch 10 are stored in the buffer 12.

On the other hand, the data content comparison circuit 24 constantly monitors the signal lines of the active system switch 10 and the standby system switch 20, and when it detects that a cell has been input, acquires the cell (step S1 in FIG. 2). ), It is determined whether they are the same (step S2).

When the data content comparison circuit 24 determines that the input cells match, it does nothing particularly. For this reason,
The input cell is stored in the buffer 22 by the write control circuit 25.
(Step S7).

On the other hand, when the data content comparing circuit 24 determines that the cell input to the active switch 10 and the cell input to the standby switch 20 are different, the data content comparing circuit 24 outputs a mismatch signal indicating that they are not the same to each other. 23 (step S3).

In response to the non-coincidence signal, the cell retention number detection circuit 23 stores the cells determined to be
2 is not counted as a stored cell (step S4).

The data content comparison circuit 24 also supplies a mismatch signal to the write control circuit 25 (step S5).

In response to the mismatch signal, the write control circuit 25 controls the buffer 22 so as not to store the cells determined to be non-identical, and discards the cells determined to be non-identical from the standby switch 20. (Step S
6).

On the other hand, the T cell detection circuits 11 and 21 constantly monitor the signal lines of the active system switch 10 and the standby system switch 20, and constantly determine whether or not the T cell has been input.

The T cell detection circuit 11 is provided with the active switch 1
When a T cell is detected among the cells input to 0, a signal notifying that the T cell has been detected is transmitted to the cell staying number detection circuit 13 (step S11).

In response to the T cell detection notification signal, the cell retention number detection circuit 13 detects the number of cells stored in the buffer 12 and notifies the difference calculation circuit 26 of the standby switch 20 (step S12).

On the other hand, the standby T cell detection circuit 21 transmits a T cell detection notification signal to the cell retention number detection circuit 23 when a T cell is detected among the cells input to the standby switch 20. (Step S13).

The cell count detection circuit 23 that has received the T cell detection notification signal counts the number of cells stored in the buffer 22 and notifies the difference calculation circuit 26 (step S14).

The difference calculation circuit 26 compares the number of cells notified from the cell retention number detection circuits 13 and 23, and calculates the number of cells corresponding to the difference (step S15).

The difference calculation circuit 26 determines that the calculated number of cells is 0
Is determined, and if it is 0, nothing is performed (step S16).

On the other hand, when it is determined that the number of cells corresponding to the difference is not 0, a control signal corresponding to the number of cells corresponding to the difference is supplied to the buffer 22 (step S17).

For example, when the difference calculation circuit 26 calculates that the number of cells supplied from the cell retention number detection circuit 13 is larger than the number of cells supplied from the cell retention number detection circuit 23, the read control circuit 27 supplies the buffer 22 with a control signal for stopping the reading of the number of cells corresponding to the difference (step S17). Here, the cell retention number detection circuit 13
The number of cells notified from the cell is 4 cells, the cell retention number detection circuit 2
Assuming that the number of cells notified from 3 is 2 cells, it is determined that the number of cells notified from the cell retention number detection circuit 13 is 2 cells larger than the number of cells notified from the cell retention number detection circuit 23, and the buffer 22 Of the two cells is stopped.

On the other hand, when the difference calculation circuit 26 calculates that the number of cells supplied from the cell retention number detection circuit 13 is smaller than the cell retention number detection circuit 23, the read control circuit 27 A control signal for instructing to postpone the reading of the desired number of cells is supplied to the buffer 22 (step S
17). Here, assuming that the number of cells notified from the cell retention number detection circuit 13 is 3 cells and the number of cells notified from the cell retention number detection circuit 23 is 4 cells, the cell retention number detection circuit 23
It is determined that the number of cells notified from the cell staying number detection circuit 13 is smaller by one cell than the number of cells notified from, and a control signal is output to postpone reading of cells from the buffer 22 by one cell.

According to the present embodiment described above, when the data content comparison circuit 24 determines that the input cells input to the active switch 10 and the standby switch 20 are different, the write control circuit 25 The buffer 22 controls so that the input cell is not stored, and the cell staying number detection circuit 23 controls so that the corresponding cell is not counted as the cell stored in the buffer 22. Also, when the T cell is detected, the difference calculation circuit 26 compares the number of cells stored in the buffers 12 and 22 and determines that the number of cells stored in the buffer 12 is larger. In addition, the read control circuit 27 stops the reading of the cells stored in the buffers 22 for the number of cells of the difference,
When it is determined that the number of stored cells is smaller than the number of cells stored in the buffer 22, the control is made to advance the cells stored in the buffer 22 by the number of cells of the difference. Accordingly, when the selection circuit 3 detects a T cell, the instantaneous interruption switching can be performed when the switching operation from the active switch 10 to the standby switch 20 is performed.

This point will be described based on a specific example.

First, as shown in FIG. 4 (A), when cells A and B are both stored in the buffers 12 and 22, a new cell is input, and this cell is switched by C and D for some reason. It is assumed that they are different from each other. In this case, the data content comparison circuit 24 determines that the two cells are different, and the write control circuit 25 does not write the cell D into the buffer 22. As a result, only the cell C is stored in the buffer 12, as shown in FIG.

In this state, as shown in FIG. 5, it is assumed that a T cell and cells E and F are sequentially input (original cells A, B,...).
Are read out sequentially, but are shown as they are for easy understanding). In this case, the T cell detection circuits 11 and 2
1 detects that a T cell has been input, and the cell retention number detection circuits 13 and 23 output the cell numbers 3 and 2 stored in the buffers 12 and 22, respectively. The difference calculation circuit 26
A control signal indicating that there is one more cell stored in the buffer 12 is supplied to the read control circuit 27. The read control circuit 27 stops reading cells for one cell.

For this reason, the cell A is supplied to the selection circuit 3 from the active system switch 10, and nothing is supplied from the standby system switch 20. Subsequently, the cell B is supplied from the active system and the cell A is supplied from the standby system, and subsequently, the T cells are supplied from the active system and the standby system. Accordingly, the selection circuit 3 selects and outputs the cells A and B from the active switch 10 and then switches in response to the T cell. The cells E, F,... Are subsequently supplied from the active system and the standby system, and the selection circuit 3
Selects the cells E, F,... Supplied from the switch 20.

Accordingly, the selection circuit 3 can switch between the active system and the standby system without an instantaneous interruption.

Next, for some reason, cells A and B are stored in buffer 12 as shown in FIG.
In a state where cells X, Y, A, and B are stored in 2, a T cell and cells C and D are sequentially input. In this case, the T cell detection circuits 11 and 21 detect the input of the T cell, and the cell retention number detection circuits 13 and 23 output the cell numbers 2 and 4 respectively. The difference calculation circuit 26 includes the buffer 12
Is supplied to the read control circuit 27, indicating that the number of cells stored in is less than two. The read control circuit 27 delays the cell reading by two cells.

Therefore, while the cell A is supplied from the active switch 10 to the selection circuit 3, the cells X, Y, A (or only A) are supplied from the standby switch 20. Subsequently, the cell B is supplied from the active system and the cell B is supplied from the standby system, and subsequently, the T cell is supplied from the active system and the standby system. Therefore, the selection circuit 3 includes the active switch 10
After selecting and outputting the cells A and B from, the cell is switched in response to the T cell. The cells C, D,... Are subsequently supplied from the active system and the standby system.
Are supplied from cells C, D,...

Therefore, the selection circuit 3 can switch between the active system and the standby system without an instantaneous interruption.

The present invention is not limited to the above embodiment, but can be variously modified.

The present invention is not limited to the above-described embodiment, but can be variously modified and applied. The circuit configuration is not limited as long as it has a function for executing the above-described processing. Can be arbitrarily changed.

[0068]

As described above, the ATM of the present invention is
The cross-connect device can switch between the active system and the standby system without an instantaneous interruption.

[0069]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM cross-connect device of the present invention.

FIG. 2 is a flowchart illustrating a data comparison process.

FIG. 3 is a flowchart illustrating a difference calculation process.

FIG. 4 is a diagram for explaining an operation of the ATM cross-connect device shown in FIG. 1;

FIG. 5 is a diagram for explaining the operation of the ATM cross-connect device shown in FIG.

FIG. 6 is a diagram for explaining the operation of the ATM cross-connect device shown in FIG. 1;

FIG. 7 is a block diagram showing a configuration of a conventional ATM cross-connect device.

FIG. 8 is a diagram for explaining the operation of a conventional ATM cross-connect device.

[Explanation of symbols]

 1,101 branch circuit 2,102 T cell insertion circuit 3,103 selection circuit 10,110 active system switch 11,21,111,121 T cell detection circuit 12,22,112,122 buffer 13,23,113,123 cell Staying number detection circuit 20, 120 Stand-by switch 23, 123 Cell staying number detection circuit 24 Data content comparison circuit 25 Write control circuit 26, 126 Difference calculation circuit 27, 127 Read control circuit

Claims (4)

[Claims] A branch circuit for branching an input cell into a working switch and a standby switch; and an insertion circuit for inserting an instruction cell for instructing switching between the working switch and the standby switch into the input cell. Connected to the working system switch and the protection system switch, and when the designated cell is detected in the cells supplied from the working system switch and the protection system switch, from the working system switch to the protection system switch. An ATM cross-connect device comprising: an output unit that outputs a cell supplied by switching to an external device, wherein the active switch stores the input cell and selects the stored cell by the selection circuit. A first buffer that outputs the designated cell to the working switch; and a first buffer that detects that the designated cell has been input to the working switch. And a first cell retention number detecting means for detecting the number of cells stored in the first buffer when the designated cell is detected, wherein the standby switch stores the input cell and A second buffer that outputs the stored cell to the selection circuit, a determination unit that determines whether the cells input to the active switch and the standby switch are the same, and the determination unit includes: Control means for controlling not to store the cell corresponding to the second buffer when it is determined that they are not the same, and a second means for detecting that the designated cell has been input to the standby switch.
A second cell retention number detection means for detecting the number of cells stored in the second buffer when the second detection means detects the designated cell; A comparison means for comparing the number of cells detected by the second cell retention number detection means, and a cell number detected by the second cell retention number detection means by the first cell retention number detection means. When it is determined that the number is smaller than the number of detected cells,
Means for stopping the reading of the cells stored in the second buffer by the number of cells corresponding to the difference, and when the second cell staying number detecting means determines that the number of cells detected is larger. Means for delaying the reading of cells stored in the second buffer by the number of cells corresponding to the difference;
An ATM cross-connect device, comprising: an instruction unit comprising: 2. The control means controls the second cell staying number detecting means so that the corresponding cell is not counted as a cell stored in the buffer when the determining means determines that the cells are not the same. The ATM cross-connect device according to claim 1, further comprising: 3. An ATM cross-connect device for selecting and outputting cells supplied from an active switch and a standby switch, comprising: a branching unit for supplying input cells to the active switch and the standby switch; An active buffer for storing the input cells from the means and outputting the stored cells; a standby buffer for storing the input cells from the branching means and outputting the stored cells; Discriminating means for discriminating whether or not a switch and a cell input to the standby switch are the same; control for controlling not to store the corresponding cell in the standby buffer when the discriminating means determines that the cells are not the same; And an ATM cross-connect device. 4. A detecting means for detecting the input of an instruction cell to the working switch and the protection switch, and the number of cells stored in the working and protection buffers in response to the detection by the detecting means. Are detected and compared, and when it is determined that the number of cells stored in the standby buffer is smaller than the number of cells stored in the active buffer, the standby buffer stores only the number of cells corresponding to the difference. When the number of cells stored in the standby buffer is determined to be greater than the number of cells stored in the active buffer, the standby buffer stores only the number of cells corresponding to the difference. 4. The AT according to claim 3, further comprising: means for postponing the reading of the cell in which the cell is read.
M cross connect device.