JPH10200541A - Cell division type atm switch having cell restoration check function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect whether or not a division origin is the same, before each partial cell is restored into an original cell at a cell combination part of a cell division switch. SOLUTION: In each partial cell switch 2, after a cell multiplex part 12 multiplexes plural partial cells 18 inputted from a cell division part and synchronizes them among the partial cell switches. A time stamp changed in a timing of each multiplexed partial cell time is given to each partial cell by a time stamp giving part 13 and a cell combination part compares time stamps which are given to each partial cell to detect whether or not the division origin is the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching system, and more specifically to a switching system.
d Integrated Service Digital Network) related to ATM switches applied to switches.

[0002]

2. Description of the Related Art As a method of constructing a large capacity ATM switch, a cell division type ATM switch is disclosed in Japanese Patent Laid-Open No. 4-9893.
No. 7, "ATM switch and control method thereof" is proposed. The advantage of this method is that when the cells are divided and each divided partial cell is independently switched and controlled by multiple switching boards, the pin neck and processing capacity of the switching board can be configured by a single switching board. This is a point that can be reduced.

FIG. 2 shows a configuration example of a cell division type ATM switch in which a conventional cell is divided into four parts. The cell division type ATM switch has cell division units 1-0 to 1-n, the same number of partial cell switches 2-0 to 2-3 as the number of cell divisions,
And cell coupling units 3-0 to 3-n. Here, it is assumed that the ATM cells 5A and 7A are input to the cell division unit 1-0, and the ATM cells 6A are input to the cell division unit 1-n from the input side line corresponding unit, and are switched to the route n. An operation example of each unit will be described.

In the cell division unit, the cells 5A, 6A and 7A arriving at the input-side line corresponding unit are each divided into four partial cells 5A.
After dividing into −0-5-3, 6-0-6-3, and 7-0-7-3, and assigning a routing tag toward the output route n to each partial cell, each partial cell is divided into a corresponding portion. Cell switch 2
-0 to 2-3 are transmitted synchronously.

[0005] The partial cell switches 2-0 to 2-3 correspond to the output route n indicated by the routing tag assigned to each partial cell from the cell division unit belonging to each input highway. Switching is synchronously controlled by the control unit 4 so as to be buffered in the queue buffers 8-0 to 8-3.

In the cell coupling section 3-n corresponding to the output path n, the partial cells output from the respective partial cell switches in synchronism are merged, and the original ATM cells 5A, 6A and 7A are reproduced and output. Send to the line corresponding unit.

[0007]

By the way, the cell division type switch requires exactly the same operation between the partial switches. Therefore, when an instantaneous error occurs in one of the partial cell switches and erroneous routing of the partial cell occurs, the buffering operation of the partial cell corresponding to a certain output path differs from other partial cell switches, There is a problem that the partial cells having the same division source are not output in synchronization, and the cells are not correctly restored in the cell combining unit.

This example will be described with reference to FIG. Queue buffer 8 corresponding to output route n of partial cell switch 2-1
Since the partial cell 6-1 to be buffered at 1 is misrouted, it operates differently from the queue buffers 8-0, 8-2, 8-3 of the other partial cell switches. In the cell combiner 3-n for restoring the partial cells output from the queue buffer 8, the cells are not correctly restored because the partial cells having the same division source are not output in synchronization.

In addition, this effect propagates to subsequent correctly routed subcells and continues until the queue buffer 8 is empty. Therefore, in the cell coupling section of the cell division type switch, it is detected whether or not partial cells having the same division source are correctly and synchronously input, and if a malfunction is detected, the corresponding cell division type switch corresponds. Need to reset queue buffer.

Japanese Unexamined Patent Publication No. 4-98937, "ATM switch and its control method", addresses this necessity, and a method in which an error correction code is added before cell division and inspection is performed in a cell combining unit. Although this method has been proposed, this method has a disadvantage that the number of bits occupied by the error correction code portion becomes considerably large, thereby limiting the throughput of the main signal.

A first object of the present invention is to provide a cell division type ATM.
It is an object of the present invention to provide means for detecting whether a division source is the same in a cell coupling unit without using an error correction code in a switch.

A second object of the present invention is to provide a cell division type ATM.
In the switch, in order to avoid a buffer reset due to an instantaneous routing error as much as possible, the timing correction of a subsequent partial cell input at a timing shifted to the cell coupling part due to the influence of partial cell loss or erroneous insertion of a partial cell is performed. And to provide a means for correctly restoring the original cell.

[0013]

In order to achieve the first object, the present invention provides an ATM switch having cell dividing means, partial cell switching means, and cell coupling means. Output
The cell combining unit has a code assigning unit that assigns a common code to all partial cells having the same division source cell,
Code comparing means for comparing codes assigned to a plurality of input partial cells with each other to determine whether the source cells of the partial cells are the same, and restoring the cells in accordance with the comparison result of the code comparing means A control unit for controlling the operation.

In order to achieve the first object, according to the present invention, in an ATM switch having a cell dividing means, a partial cell switching means and a cell coupling means, each of the plurality of partial cell switching means has an input. Code assigning means for assigning a code generated so as to be changed for each partial cell to all partial cells having the same division source cell in common, wherein the cell combining means includes Code comparing means for comparing codes assigned to a plurality of partial cells to be compared with each other to determine whether the division source cells of the partial cells are the same, and a cell restoring operation according to the comparison result of the code comparing means. And a control unit for controlling the

In order to achieve the second object, according to the present invention, in an ATM switch having a cell dividing means, a partial cell switching means, and a cell combining means, the cell combining means is required to correctly restore an original cell. And a combining timing correcting means for detecting a timing shift of a partial cell having the same division source, correcting the detected timing shift, and restoring the partial cell.

More specifically, for example, in the invention for achieving the first object, the partial cell switch means comprises a queue buffer for each output route for waiting for a partial cell from each input route. And a queue length information providing unit for providing queue length information indicating the number of partial cells for each output route stored in the queue buffer when reading the partial cells from the queue buffer, The cell merging means collects a partial timing read buffer from the merged timing correction buffer for storing the partial cells output from the respective partial cell switch means, and restores the original cell. A cell restoration unit, a queue length comparing unit that compares the queue length information given to each partial cell, and a comparison of the queue length and the code It shall further comprising a reading control section for controlling the read operation of the coupling timing correction buffer in accordance with the result.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an ATM switch according to the present invention will be described with reference to FIGS. In the following description, for example, only a portion different from the configuration of the conventional split type ATM switch described in the section of the conventional technology will be described, and the description of the same configuration will be omitted.

The AT, which is one of the characteristic configurations of the present embodiment,
FIG. 1 shows an example of the configuration of each partial cell switch of the M switch.

Each partial cell switch according to the present embodiment includes:
Input highway 10 (10-0 to 10-n), cell multiplexing unit 12, control unit 4, time stamp adding unit 13, cell buffer unit 15, cell separation unit 16, and output highway 17 (17-0 to 17-n) ).

The time stamp adding unit 13 includes, for example, a counter unit that generates a continuous numerical value to be added as a time stamp value, an adding unit that writes the value indicated by the counter unit into a specific area of each partial cell, A reset unit for resetting the value of the counter unit in response to the reset signal. The counter section increments the value synchronously among all the partial switches included in the ATM switch. For example, the counter section increments a clock signal from a system common clock generation section in the ATM switch (not shown). Work based on.

Each of the partial cells 18 (18-0 to 18-n) input from each input highway has a routing tag 18R.
(18R-0 to 18R-n) and are multiplexed in the cell multiplexing unit 12. To the partial cells output from the cell multiplexing unit 12, a time stamp value updating unit 13 gives a time stamp value 19 updated every one partial cell time (multiplex slot time) after multiplexing.

The counter section of the time stamp giving section 13 is periodically reset by a reset pulse signal 20 synchronized between all the partial cell switch sections, and gives a time stamp addition synchronized between all the partial cell switch boards. Making it possible. Since the reset pulse signal 20 needs to be input in synchronization between all the partial switches,
For example, it is assumed that it is generated periodically or at another timing based on a clock signal from the above-described system common clock generation unit.

For example, instead of the reset pulse signal 20, the counter reset is triggered by an empty cell for speed matching that is periodically inserted for speed matching with a synchronous digital hierarchy (SDH) in a specific line corresponding unit. Or the like may be used.

The routing information 18C is extracted from the routing tag 18R attached to each partial cell, and is sent to the control unit 4 before or after each partial cell is input to the cell multiplexing unit 12.

After the routing information 18C is extracted,
The area of the routing tag 18R of each partial cell can be used as an area for writing the above-described time stamp. The control unit 4 uses the routing information 18C to transfer each partial cell to the queue buffer 21 (21-0 to 21-) corresponding to a desired output route configured in the cell buffer 15.
n), a write address (W
A) Control for generating 22 and control for generating a read address (RA) 23 for cyclically reading cells from the cell buffer 15 for each output path are performed.

The partial cells 24 (24-0 to 24-n) cyclically read from the cell buffer unit 15 are distributed to respective output routes by the cell separation unit 16, and output highways 17
Is transmitted to the cell combining unit 3 through

Next, an example of the configuration of the cell coupling section 3 of the present embodiment provided corresponding to the partial cell switch 2 will be described with reference to FIG.

The cell combining unit according to the present embodiment includes a restoration determination register 31 (31-0 to 31-3), a time stamp comparison unit 32, a register read control unit 33, and a cell restoration unit 34.

The partial cells 30 (30-0 to 30-3) output from the respective partial cell switches 2 are taken into the restoration determination registers 31 (31-0 to 31-3) and assigned to the respective partial cells. The time stamp comparison unit 32 compares whether the values of the time stamps T0 to T3 are all the same, and notifies the register read control unit 33 of the comparison result.

When the time stamp values of the respective partial cells are all the same, the register read controller 33 reads all the partial cells from the restoration determination register 31 and restores the original cells 30A by the cell restoration unit 34. After that, it transmits to the output side line corresponding unit. If all the time stamps are not the same, all the partial cells in the restoration determination register are discarded.

Further, if the timestamps are not all the same and occur N times (N is the number of times of protection) consecutively, the queue buffers of the corresponding routes of all the partial cell switches 2 are reset. , The control unit 4 of each partial cell switch 2.

According to the configuration described above, when restoring a partial cell in the cell combining unit of the present embodiment, it is checked whether the division source of the partial cell is the same, and only the correctly restored cell is checked. Can be sent to the output side line corresponding unit.

Although the continuous numerical value generated by the counter is used as the time stamp used in the present embodiment, the present invention is not limited to this. In the present invention, a time stamp is used to distinguish a partial cell having the same division source sent from all the partial switches in synchronization from other partial cells in which erroneous insertion has been performed. Therefore, as long as the codes assigned to the temporally consecutive partial cells are not the same, a time stamp assigning unit having another configuration may be used.

Next, the second embodiment of the ATM switch according to the present invention will be described.
An embodiment will be described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The partial cell switch 2 of the present embodiment is similar to that of FIG.
As shown in (1), in the partial cell switch according to the first embodiment, a queue length information providing unit 25 is provided between the cell buffer unit 15 and the cell separating unit 16.

In the partial cell switch 2 of the present embodiment, as in the case of the first embodiment, after each partial cell is multiplexed, a time stamp 19 synchronized between all switch boards is set. Granted. The control unit 4 manages the number of cells (queue length information) of the partial cells queued in the queue buffer formed in the cell buffer unit 15 for each output path, and reads each partial cell. At this time, queue length information (or several lower bits of the queue length information) is added via the queue length information adding unit 25.

It is assumed that the time stamp and the queue length information are written by using the area of the routing tag 18R which becomes unnecessary after the multiplexing of the partial cells. With such a configuration, the partial cells 24 (24-0 to 24-n) output from the cell separation unit 16 to the output highways 17 respectively have the time stamps 24T (24T-0 to 24T-n).
And queue length information 24C (24C-0 to 24C-n).

FIG. 6 shows an example of the configuration of the cell coupling section 3 in this embodiment. The cell combining unit 3 of the present embodiment is different from the cell combining unit of the first embodiment in that the buffer 35 for combining timing correction (35-0 to 35-3) is used instead of the restoration determination register 31 and the register read control unit 33.
5-3) and a buffer read control unit 37, and a queue length comparison unit 37 is further provided.

In this embodiment, the partial cells output from each of the partial cell switches 2 (2-0 to 2-3) are combined with the combined timing correction buffer 35 (35) in the cell combining unit 3.
−0 to 35-3). In the time stamp comparing unit 32, the time stamps T0 to T3 assigned to the leading partial cells of the respective combined timing correction buffers 35
Are compared, and the result is stored in the buffer read control unit 3.
Notify 7. The queue length comparing unit 36 compares the queue length information C0 to C3 assigned to each partial cell, and notifies the buffer reading control unit 37 of the result.

The buffer read control unit 37 controls the reading of the partial cells from the coupling timing correction buffer 35 based on the information from the time stamp comparison unit 32 and the queue length comparison unit 36. FIG. 7 shows an example of this control algorithm.

In the control algorithm of the present embodiment, first, the time stamp comparing unit 32 compares the time stamps from the respective partial cells (step 40). If all the time stamps are determined to be the same, all the time stamps are determined. The partial cells are read from the coupling timing correction buffer 35 and sent to the cell restoring unit 34 to restore the original cells (step 41).

Also, when only the time stamp Tk given to the partial cell from a certain route k is different from the time stamp from another route and it has not occurred N times consecutively (step 40). , Step 43, step 4
In the case of N in all 4), reading of partial cells is controlled based on the queue length comparison result (step 42). The read control can be divided into the following three cases.

If only the queue length information Ck assigned to the partial cell from the route k is one less than the queue length information from the other route, it is determined that a cell loss has occurred in the partial cell switch k. The coupling timing correction buffer 35 is controlled so as to hold the partial cell of the route k and discard the partial cell of the other route.

If only the queue length information Ck given to the partial cell from the route k is larger than the queue length information from the other route by one, it is determined that an erroneous cell insertion has occurred in the partial cell switch k. Judgment is made, and the coupling timing correction buffer 35 is controlled so that the partial cell on the route k is discarded and the partial cell on the other route is held.

If the relationship between the queue length information does not apply to any of the above and none of the above, it is estimated that the error of the partial cell switch is not instantaneous, so that the partial cells of all the routes are discarded. , Synchronously reset the queue buffers of the corresponding routes of all the partial cell switches. As a method of the synchronous reset, for example, a control cell for synchronously controlling the in-channel control of the partial cell switch is transmitted from one path of the cell division unit, and all the partial cell switches are synchronously reset. There is.

In the time stamp comparing section 32, when an event in which all the time stamps are not the same occurs N times consecutively (N is the number of times of protection) (Y in step 43), or when a plurality of time stamps are different. In (Y in step 44), the corresponding queue buffer of the partial cell switch is reset (step 45).

In the present embodiment, the timing difference between the partial cells is detected by checking the time stamp and the queue length information assigned to the partial cells. However, the present invention is not limited to this. Not something. For example, in the case of a simple configuration in which the number of cell divisions is two, the partial cells themselves are compared, and if it can be determined that the cells of the division source are the same, they are directly combined, and it is determined that the division sources are not the same. In such a case, the above-described determination may be performed again after the one partial cell is advanced or delayed by one cell using the coupling timing correction buffer as described above.

Next, an operation example in the case where a partial cell loss occurs in a certain output path due to an instantaneous error in one of the partial cell switches of the present embodiment will be described. FIG. 8 shows an example of the configuration of the above-described ATM switch including the partial cell switch and the cell coupling unit.

In the cell buffer 8-1 corresponding to the output route n in the partial cell switch 2-1 of the present embodiment, one of the partial cells 6-1 of the cell 6A is erroneously routed to another route. In this case, the queuing state of the partial cell buffer 8-1 is different from the queuing states of the cell buffers 8-0, 8-2, and 8-3 of the other partial cell switches.

In this state, when the partial cells are read from the respective cell buffers, as shown in FIG.
-3 is input to the coupling timing correction buffer 35. Since the time stamps 5T-0 to 5T-3 assigned to the partial cells 5-0 to 5-3 are all the same, the buffer read controller 37 causes the partial cells 5-0 to 5-T
3 are read all at once and the original cell 5
A is restored.

At the next timing, as shown in FIG. 10, partial cells 6-0, 7-1, 6-2, 6-3
Is input to the coupling timing correction buffer 35.
In the time stamp comparing unit 32 and the queue length comparing unit 36, the time stamp 7T-
1 is different from the others, and the queue length information 7C-1 assigned to the partial cell 7-1 is different from the other queue length information 6C-0,
Since there is one less than 6C-2 and 6C-3, it is determined that a cell loss has occurred in the partial cell switch 2-1.

As a result, the buffer read control unit 37 sends the connection timing correction buffers 35-0, 35-2,
35-3 so as to discard the partial cells 6-0, 6-2 and 6-3, and a buffer 35-1 for coupling timing correction.
Is instructed to hold the partial cell 7-1, so that the cell restoration is not executed.

At the next timing, as shown in FIG. 11, the partial cells 7-0, 7-2, 7-3 are connected to the combined timing correction buffers 35-0, 35-2, 35-.
3 is input. These partial cells and the partial cell partial cell 7-1 held in the combined timing correction buffer 35-1 are time stamps 7T-0 to 7T-3.
Are all the same, they are read all at once and restored to the original cell in the cell restoration unit.

Next, a description will be given of an operation example in which a partial cell is erroneously inserted into a certain output path due to one momentary error of the partial cell switch of the present embodiment.

In the present embodiment, as shown in FIG. 12, in the cell buffer 8-1 corresponding to the output path n in the partial cell switch 2-1, the partial cell to be routed to another output path If 9-1 is misrouted, the queuing state of the partial cell buffer 8-1 is changed to the cell buffers 8-0, 8-2,
8-3 is different from the queuing state.

In this state, when the partial cells are read from each cell buffer, as shown in FIG.
-3 is input to the coupling timing correction buffer 35. Since the time stamps 5T-0 to 5T-3 assigned to the partial cells 5-0 to 5-3 are all the same, the buffer read controller 37 causes the partial cells 5-0 to 5-T
3 are read all at once and the original cell 5
A is restored.

At the next timing, as shown in FIG. 13, partial cells 6-0, 9-1, 6-2, 6-3
Is input to the coupling timing correction buffer 35.
In the time stamp comparing unit 32 and the queue length comparing unit 36, the time stamp 9T-
1 is different from the others, and the queue length information 9C-1 assigned to the partial cell 9-1 is different from the other queue length information 6C-0,
Since it is 1 larger than 6C-2 and 6C-3, it is determined that partial cell erroneous insertion has occurred in the partial cell switch 2-1.

As a result, from the buffer read control unit 37, the coupling timing correction buffers 35-0, 35-2,
35-3 is configured to hold the partial cells 6-0, 6-2, and 6-3.
Since -1 is instructed to discard the partial cell 9-1, the cell restoration is not executed.

At the next timing, as shown in FIG. 14, partial cells 7-0, 6-1, 7-2, 7-3
Are combined timing correction buffers 35-0, 35-
1, 35-2, and 35-3. Partial cell 6-1 input to the coupling timing correction buffer 35-1
And the coupling timing correction buffers 35-0, 35-
2, partial cells 6-0, 6 held in 35-3
-2 and 6-3 are time stamps 6T (6T-0 to 6T).
-3) are all the same, and are therefore read out all at once and restored to the original cell 6A in the cell restoration unit 34.

At the next timing, as shown in FIG. 15, the partial cell 7-1 is input to the coupling timing correction buffer 35-1. The partial cell 7-1 and the leading partial cells 7-0, 7-2, and 7-3 of the combined timing correction buffers 35-0, 35-2, and 35-3 have a time stamp 7T (7T-0 to 7T). -3) are all the same, so that they are read all at once and the original cell 7
A is restored.

[0061]

According to the present invention, before restoring each partial cell to the original cell without using an error correction code in the cell coupling section of the cell division type ATM switch, the division source is the same. It is possible to provide a means for detecting the presence.

Further, according to the present invention, there is provided a means for correcting the cell combination timing of a subsequent partial cell which is input at a shifted timing to the cell coupling section under the influence of partial cell loss or partial cell erroneous insertion. Can be provided. As a result, unnecessary resetting of the buffer of the partial cell switch due to an instantaneous routing error can be avoided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration example of a partial cell switch having a time stamp adding unit according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a conventional cell division switch.

FIG. 3 is an explanatory diagram of a partial cell assembly error that can occur in a conventional cell division type switch.

FIG. 4 is an explanatory diagram showing a configuration example of a cell coupling unit corresponding to the switch configuration of FIG. 1;

FIG. 5 is an explanatory diagram showing a configuration example of a partial cell switch having a time stamp adding unit and a queue length information adding unit according to the present invention.

FIG. 6 is an explanatory diagram showing a configuration example of a cell coupling unit corresponding to the switch configuration of FIG. 5;

FIG. 7 is a flowchart showing a read control algorithm in a coupling timing correction buffer;

FIG. 8 is an explanatory diagram for explaining an operation example when a partial cell loss error occurs in a certain output route.

FIG. 9 is an explanatory diagram for explaining an operation example in a cell coupling unit when a partial cell loss error occurs in a certain output path.

FIG. 10 is an explanatory diagram for explaining an operation example in a cell coupling unit when a partial cell loss error occurs in a certain output route.

FIG. 11 is an explanatory diagram for explaining an operation example in a cell combining unit when a partial cell loss error occurs in a certain output route.

FIG. 12 is an explanatory diagram for describing an operation example when an erroneous insertion error of a partial cell occurs in a certain output route.

FIG. 13 is an explanatory diagram for explaining an operation example in a cell combining unit when an erroneous insertion of a partial cell occurs in a certain output route.

FIG. 14 is an explanatory diagram for describing an operation example in a cell combining unit when an erroneous insertion error of a partial cell occurs in a certain output route.

FIG. 15 is an explanatory diagram for describing an operation example in a cell combining unit when an erroneous insertion of a partial cell occurs in a certain output path.

[Explanation of symbols]

1: cell division unit, 2: partial cell switch, 3: cell connection unit, 4: control unit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuo Kano 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture

Claims (14)

[Claims] 1. A cell division unit for dividing a cell from a line corresponding unit into a plurality of partial cells, a partial cell switch unit for switching the partial cells, the same number of divisions as the number of divided cells, In an asynchronous transfer mode (ATM) switch having cell combining means for collecting partial cells output from the cell switching means and restoring the original cells, the division source output from the plurality of partial cell switching means is provided. The cell combining unit has a code assigning unit that assigns a common code to all partial cells having the same cell, and the cell combining unit compares the codes assigned to the plurality of input partial cells with each other. Sign comparison means for judging whether or not the division source cells are the same, and a control unit for controlling a cell restoration operation according to the comparison result of the sign comparison means. TM switch. 2. A cell dividing means for dividing a cell from a line corresponding unit into a plurality of partial cells, a partial cell switch means for switching the partial cells, the number of which is equal to the number of divisions of the cells, An asynchronous transfer mode (ATM) switch having cell combining means for collecting partial cells output from the cell switching means and restoring the original cells, wherein each of the plurality of partial cell switching means comprises an input part; A code generation unit configured to commonly assign a code generated so as to change for each cell to all partial cells having the same division source cell; and Code comparing means for comparing the codes assigned to the partial cells with each other to determine whether or not the division source cells of the partial cells are the same, and a cell restoration operation in accordance with the comparison result of the code comparing means. ATM switch; and a control unit for controlling. 3. The method according to claim 2, wherein the code assigning means assigns the code to the partial cells after the partial cells input to the partial cell switching means provided with the code assigning means are multiplexed. An ATM switch characterized by the above-mentioned. 4. The apparatus according to claim 2, wherein the code assigning means includes a counter section controlled to count up synchronously among the plurality of partial cell switch means, and a value indicated by the counter section as the code. An ATM switch comprising: a counter value assigning unit that assigns a value to a cell. 5. The apparatus according to claim 4, wherein said code assigning means further comprises a reset section for synchronously resetting a value generated by said counter section among said plurality of partial cell switch means. A
TM switch. 6. The reset unit according to claim 5, wherein the reset unit of the code adding unit performs a reset operation in accordance with the timing of an empty cell for speed matching with a synchronous digital hierarchy (SDH) periodically inserted in a line corresponding unit. An ATM switch characterized by executing. 7. The ATM switch according to claim 4, wherein the counter value assigning unit of the sign assigning means writes the sign in an area of a routing tag provided in the partial cell. 8. The method according to claim 1, wherein each of the plurality of partial cell switching units further includes a queue buffer for each output path for waiting for a partial cell from each input path. An ATM switch resetting a queue buffer of a corresponding output route provided in all of the partial cell switch means when the comparison result by the means does not match continuously for a specific number of times or more. 9. The method according to claim 1, wherein each of the plurality of partial cell switching means further includes a queue buffer for each output path for waiting for a partial cell from each input path. As a result of the comparison by the means, when a plurality of codes that do not match are detected, the ATM switch provided in all of the partial cell switch means resets the queue buffers of the corresponding output routes. 10. A cell dividing means for dividing a cell from a line corresponding unit into a plurality of partial cells, a partial cell switch means for switching the partial cells, the number of which is equal to the number of divisions of the cells, In an asynchronous transfer mode (ATM) switch having cell combining means for collecting the partial cells output from the cell switching means and restoring the original cells, the cell combining means may correctly restore the original cells.
An ATM switch comprising a coupling timing correction means for detecting a timing shift of a partial cell having the same division source, correcting the detected timing shift, and restoring the partial cell. 11. The device according to claim 2, wherein said partial cell switch means comprises: a queue buffer for each output route for waiting for a partial cell from each input route;
A queue length information providing unit for providing queue length information indicating the number of partial cells for each output route stored in the queue buffer when reading out the partial cells from the queue buffer; The combining unit includes a combining timing correction buffer for storing the partial cells output from each of the partial cell switching units, and a cell restoration unit that collects the partial cells read from the combining timing correction buffer and restores the original cell. Unit, a queue length comparing means for comparing the queue length information given to each partial cell, and a read control for controlling a read operation of the combined timing correction buffer according to a result of comparing the queue length and the code. And an ATM switch. 12. The apparatus according to claim 11, wherein said code adding means and said queue length information adding means are
An ATM switch, wherein the code and the queue length information are written in a routing tag area provided in the partial cell. 13. The read control unit according to claim 11, wherein a code in one partial cell is different from another partial cell by the code comparing means, and the code is different by the queue length comparing means. When it is determined that the queue length of the partial cell is smaller by 1, the reading of the partial cell having the different code from the combined timing correction buffer is held, and the other partial cells are discarded from the combined timing correction buffer. An ATM switch, characterized in that: 14. The read control unit according to claim 11, wherein a code in one partial cell is different from another partial cell by the code comparing means, and the code is different by the queue length comparing means. When it is determined that the queue length of the partial cell is larger by 1, the partial cell having the different code is discarded from the combined timing correction buffer, and reading of the other partial cells from the combined timing correction buffer is held. An ATM switch, characterized in that: