JP3563221B2 - Cell division type ATM switch with cell restoration inspection function - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a switching system, and more particularly, to an ATM switch applied to a broadband integrated service digital network (ISDN) switch.
[0002]
[Prior art]
As a method of configuring a large-capacity ATM switch, a cell-division ATM switch has been proposed in Japanese Patent Application Laid-Open No. 4-98937, entitled "ATM Switch and Control Method Thereof". The advantage of this method is that when the cells are divided and the divided partial cells are independently switched and controlled by a plurality of 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.
[0003]
FIG. 2 shows a configuration example of a cell division type ATM switch in which a cell according to the prior art is divided into four parts. The cell division type ATM switch is composed of 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. You. 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.
[0004]
The cell division unit divides the cells 5A, 6A, and 7A arriving at the input line corresponding unit into four partial cells 5-0 to 5-3, 6-0 to 6-3, and 7-0 to 7-3, respectively. Then, after assigning a routing tag for the output route n to each partial cell, each partial cell is synchronously transmitted to the corresponding partial cell switch 2-0 to 2-3.
[0005]
The partial cell switches 2-0 to 2-3 are provided in the queue buffer 8 corresponding 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 range of −0 to 8-3.
[0006]
In the cell combiner 3-n corresponding to the output route n, the partial cells output from the respective partial cell switches in synchronism are merged, the original ATM cells 5A, 6A, and 7A are reproduced, and the output side line responder To send to.
[0007]
[Problems to be solved by the invention]
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.
[0008]
This example is shown using FIG. Since the partial cell 6-1 to be buffered in the queue buffer 8-1 corresponding to the output path n of the partial cell switch 2-1 has been erroneously routed, the queue buffers 8-0 of other partial cell switches, It operates differently from 8-2 and 8-3. 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 synchronously.
[0009]
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. You need to reset the queue buffer.
[0010]
Japanese Unexamined Patent Publication No. Hei 4-98937 discloses an ATM switch and its control method, which also addresses this necessity. A method has been proposed in which an error correction code is added before cell division and a cell coupling unit checks this. However, this method has a disadvantage in that the number of bits occupied by the error correction code portion becomes considerably large, and the throughput of the main signal is limited.
[0011]
SUMMARY OF THE INVENTION It is a first object of the present invention to provide a means for detecting whether or not the division source is the same in a cell coupling unit without using an error correction code in a cell division type ATM switch.
[0012]
A second object of the present invention is to provide a cell division type ATM switch in which a buffer is reset due to an instantaneous routing error as much as possible. It is another object of the present invention to provide a means for correcting the timing of a subsequent partial cell input with a deviation and inputting the correct original cell.
[0013]
[Means for Solving the Problems]
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, a dividing source cell output from the plurality of partial cell switching means is provided. A code assigning means for assigning a common code to all the same partial cells, wherein the cell combining means compares codes assigned to a plurality of input partial cells with each other, and There are code comparing means for determining whether the cells are the same, and a control unit for controlling a cell restoration operation according to the comparison result of the code comparing means.
[0014]
In order to achieve the first object, according to the present invention, in an ATM switch having cell dividing means, partial cell switching means, and cell coupling means, each of the plurality of partial cell switching means includes A code assigning means for assigning a code generated so as to change for each cell to all partial cells having the same division source cell in common; Code comparing means for comparing the codes assigned to the partial cells with each other and determining whether the division source cells of the partial cells are the same, and controlling the cell restoration operation according to the comparison result of the code comparing means And a control unit.
[0015]
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, in order for the cell combining means to correctly restore an original cell, Has a combined timing correction means for detecting a timing shift of a partial cell having the same timing, correcting the detected timing shift, and restoring the partial cell.
[0016]
More specifically, for example, in the invention for achieving the first object, the partial cell switch means includes: a queue buffer for each output path for waiting for a partial cell from each input path; 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 means includes a combined timing correction buffer for storing the partial cells output from each of the partial cell switch means, and a cell restoring unit that collects the partial cells read from the combined timing correction buffer and restores the original cell. And a queue length comparing means for comparing the queue length information given to each partial cell, and according to a result of comparing the queue length and the code. It shall further comprising a reading control section for controlling the read operation of the serial coupling timing correction buffer.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the ATM switch according to the present invention will be described with reference to FIGS. In the following description, for example, only portions 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.
[0018]
FIG. 1 shows an example of the configuration of each partial cell switch of an ATM switch, which is one of the characteristic configurations of the present embodiment.
[0019]
Each partial cell switch according to the present embodiment includes an input highway 10 (10-0 to 10-n), a cell multiplexing unit 12, a control unit 4, a time stamp adding unit 13, a cell buffer unit 15, a cell separation unit 16, and an output. It is composed of highways 17 (17-0 to 17-n).
[0020]
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 a signal. The counter section increments the value synchronously among all the partial switches included in the ATM switch. For example, the counter section generates a clock signal from a system common clock generation section in the ATM switch (not shown). Work based on.
[0021]
The partial cells 18 (18-0 to 18-n) input from the respective input highways are provided with routing tags 18R (18R-0 to 18R-n) and 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.
[0022]
The counter unit of the time stamp providing unit 13 is periodically reset by a reset pulse signal 20 synchronized between all the partial cell switch units, and enables the time stamp to be given between all the partial cell switch boards. I have. Since the reset pulse signal 20 needs to be input synchronously between all the partial switches, the reset pulse signal 20 is generated periodically or at another timing based on a clock signal from the above-described system common clock generator. Shall be.
[0023]
For example, instead of the reset pulse signal 20, the counter reset is triggered by a timing of a speed matching empty cell or the like that is periodically inserted for speed matching with a synchronous digital hierarchy (SDH) in a specific line corresponding unit. May be used.
[0024]
The routing information 18C is extracted from the routing tag 18R assigned 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.
[0025]
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. Based on the routing information 18C, the control unit 4 writes data for queuing each partial cell to the queue buffer 21 (21-0 to 21-n) corresponding to a desired output route configured in the cell buffer 15. Control for generating a read address (WA) 22 and control for generating a read address (RA) 23 for cyclically reading cells from the cell buffer 15 for each output route.
[0026]
The partial cells 24 (24-0 to 24-n) cyclically read from the cell buffer unit 15 are distributed to each output path by the cell separation unit 16 and transmitted to the cell combination unit 3 through the output highway 17. .
[0027]
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.
[0028]
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.
[0029]
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 the time stamp T0 assigned to each partial cell is provided. The time stamp comparison unit 32 compares whether or not all the values of T3 are the same, and notifies the register read control unit 33 of the comparison result.
[0030]
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. Transmit to the output side line corresponding part. If the time stamps are not all the same, all the partial cells in the restoration determination register are discarded.
[0031]
Further, when the time stamps are not all the same and occur N times (N is the number of times of protection) consecutively, each of the partial buffers is reset so that the queue buffers of the corresponding routes of all the partial cell switches 2 are reset. The controller 4 of the cell switch 2 is controlled.
[0032]
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 output to the output side. It can be sent to the line corresponding unit.
[0033]
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. According to the present invention, a time stamp is used to distinguish a partial cell having the same division source transmitted 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.
[0034]
Next, a second embodiment of the ATM switch according to the present invention 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.
[0035]
As shown in FIG. 5, the partial cell switch 2 according to the present embodiment is different from the partial cell switch according to the first embodiment in that a queue length information provision unit 25 is provided between the cell buffer unit 15 and the cell separation unit 16. It is provided.
[0036]
In the partial cell switch 2 of the present embodiment, as in the case of the first embodiment, after the respective partial cells are multiplexed, a time stamp 19 synchronized between all the switch boards is given. . The control unit 4 manages the number of cells (queue length information) of partial cells queued in a 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.
[0037]
It is assumed that the time stamp and the queue length information are written using the area of the routing tag 18R which becomes unnecessary after multiplexing of the partial cells. With this 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 the queues. Length information 24C (24C-0 to 24C-n) is provided.
[0038]
FIG. 6 shows an example of the configuration of the cell coupling section 3 in the present embodiment. The cell combiner 3 of the present embodiment is different from the cell combiner of the first embodiment in that the buffer 35 (35-0 to 35-3) for combining timing correction is used instead of the restoration determination register 31 and the register read controller 33. ) And a buffer read control unit 37, and a queue length comparison unit 37 is further provided.
[0039]
In the present embodiment, the partial cells output from each of the partial cell switches 2 (2-0 to 2-3) are input to the coupling timing correction buffer 35 (35-0 to 35-3) in the cell coupling unit 3. Is done. The time stamp comparing unit 32 compares the time stamps T0 to T3 assigned to the leading partial cell of each combined timing correction buffer 35, and notifies the buffer reading control unit 37 of the result. 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.
[0040]
The buffer read control unit 37 controls the reading of the partial cells from the combined 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.
[0041]
In the control algorithm of the present example, first, the time stamp comparing unit 32 compares the time stamps from the respective partial cells (step 40), and if it is determined that all the time stamps are the same, all the combined timing corrections are performed. The partial cell is read out from the buffer 35 and sent to the cell restoring unit 34 to restore the original cell (step 41).
[0042]
Further, 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 the time stamp does not occur N times continuously (steps 40 and 43). , Step N), the reading of the partial cells is controlled based on the queue length comparison result (step 42). The read control can be divided into the following three cases.
[0043]
{Circle around (1)} When only the queue length information Ck given to the partial cell from the route k is one less than the queue length information from the other routes, 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 on the route k and discard the partial cell on the other route.
[0044]
{Circle around (2)} When 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 insertion of a cell has occurred in the partial cell switch k. Judgment is made, and the coupling timing correction buffer 35 is controlled so as to discard the partial cell on the route k and hold the partial cell on the other route.
[0045]
(3) If the relationship between the queue length information does not apply to any of the above (1) and (2), the error of the partial cell switch is presumed to be not instantaneous. The partial cells are discarded, and the queue buffers of the corresponding routes of all the partial cell switches are synchronously reset. As a method of the synchronous reset, for example, a control cell for synchronously controlling the in-channel control of the partial cell switches is transmitted from one path of the cell division unit, and all the partial cell switches are synchronously reset. There is.
[0046]
Further, in the time stamp comparing unit 32, 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 a plurality of time stamps are different (step 44). In step Y), the corresponding queue buffer of the partial cell switch is reset (step 45).
[0047]
In the present embodiment, the configuration is such that the timing deviation of the partial cell is detected by checking the time stamp and the queue length information given to the partial cell. However, the present invention is not limited to this. . 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 above-described coupling timing correction buffer.
[0048]
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.
[0049]
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.
[0050]
In this state, when the partial cells are read from each cell buffer, as shown in FIG. 9, in the corresponding cell coupling section, first, the partial cells 5-0 to 5-3 are stored in the coupling timing correction buffer 35. Is entered. 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 control unit 37 reads the partial cells 5-0 to 5-3 all at once. The cell is restored to the original cell 5A by the cell restoration unit 34.
[0051]
At the next timing, as shown in FIG. 10, the partial cells 6-0, 7-1, 6-2, and 6-3 are input to the combined timing correction buffer 35. In the time stamp comparing unit 32 and the queue length comparing unit 36, only the time stamp 7T-1 assigned to the partial cell 7-1 is different from the others, and the queue length information 7C-1 assigned to the partial cell 7-1 is different. Since it is one less than the other queue length information 6C-0, 6C-2, 6C-3, it is determined that a cell loss has occurred in the partial cell switch 2-1.
[0052]
As a result, the buffer read control unit 37 discards the partial cells 6-0, 6-2, and 6-3 to the combined timing correction buffers 35-0, 35-2, and 35-3, and corrects the combined timing. Since the buffer 35-1 is instructed to hold the partial cell 7-1, the cell is not restored.
[0053]
At the next timing, as shown in FIG. 11, the partial cells 7-0, 7-2, and 7-3 are input to the combined timing correction buffers 35-0, 35-2, and 35-3. These partial cells and the partial cell partial cell 7-1 held in the coupling timing correction buffer 35-1 are read out all at once because the time stamps 7T-0 to 7T-3 are all the same. , The original cell is restored in the cell restoration unit.
[0054]
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.
[0055]
In the present embodiment, as shown in FIG. 12, in the cell buffer 8-1 corresponding to the output route n in the partial cell switch 2-1, the partial cell 9-1 to be routed to another output route is provided. Is incorrectly routed, the queuing state of the partial cell buffer 8-1 is different from the queuing state of the cell buffers 8-0, 8-2, 8-3 of the other partial cell switches.
[0056]
In this state, when the partial cells are read from the respective cell buffers, as shown in FIG. 9, first, in the corresponding cell coupling section, the partial cells 5-0 to 5-3 are connected to the coupling timing correction buffer 35. Is input to 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 control unit 37 reads the partial cells 5-0 to 5-3 all at once. The cell is restored to the original cell 5A by the cell restoration unit 34.
[0057]
At the next timing, as shown in FIG. 13, the partial cells 6-0, 9-1, 6-2, and 6-3 are input to the combined timing correction buffer 35. In the time stamp comparing unit 32 and the queue length comparing unit 36, only the time stamp 9T-1 assigned to the partial cell 9-1 is different from the others, and the queue length information 9C-1 assigned to the partial cell 9-1 is changed. Is larger than the other queue length information 6C-0, 6C-2, 6C-3, it is determined that the partial cell switch 2-1 has erroneously inserted a partial cell.
[0058]
As a result, the buffer read control unit 37 holds the partial cells 6-0, 6-2, and 6-3 in the buffers 35-0, 35-2, and 35-3 for correcting the combined timing, and also corrects the combined timing. Instructing the use buffer 35-1 to discard the partial cell 9-1 does not execute the cell restoration.
[0059]
At the next timing, as shown in FIG. 14, the partial cells 7-0, 6-1, 7-2, and 7-3 are connected to the combined timing correction buffers 35-0, 35-1, 35-2, and 35. -3 is input. The partial cell 6-1 input to the coupling timing correction buffer 35-1, the partial cells 6-0, 6-2 held in the coupling timing correction buffers 35-0, 35-2, 35-3, 6-3 are read out all at once since the time stamps 6T (6T-0 to 6T-3) are all the same, and are restored to the original cell 6A in the cell restoration unit 34.
[0060]
At the next timing, as shown in FIG. 15, the partial cell 7-1 is input to the combined 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 the time stamp 7T (7T-0 to 7T). -3) are all the same, so they are read all at once and restored to the original cell 7A in the cell restoration unit.
[0061]
【The invention's effect】
According to the present invention, it is detected whether or not the division source is the same before restoring each partial cell to the original cell without using an error correction code or the like in the cell coupling unit of the cell division type ATM switch. It becomes possible to provide a means.
[0062]
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 with a shift in timing to a cell coupling section under the influence of partial cell loss or partial cell erroneous insertion. Becomes possible. As a result, unnecessary reset 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 combining 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 explaining 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 explaining 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 explaining an operation example in a cell combining unit when an erroneous insertion of a partial cell occurs in a certain output route.
[Explanation of symbols]
1: cell division unit, 2: partial cell switch, 3: cell connection unit, 4: control unit.

Claims (7)

A cell dividing unit for dividing a cell from the line corresponding unit into a plurality of partial cells, a partial cell switch for switching the partial cells, the same number of partial cells as the number of divided cells, and an output from the partial cell switch. An ATM (ATM) switch having cell combining means for collecting the recovered partial cells and restoring the original cells,
Each of the plurality of partial cell switch means,
Code assigning means for assigning a code generated so as to be changed for each input partial cell to all partial cells having the same division source cell in common,
A queue buffer for each output route for waiting for a partial cell from each input route,
When reading a partial cell from the queue buffer, the queue buffer has 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 ,
The code assigning means assigns the code to the partial cells after the partial cells input to the partial cell switch means provided with the code assigning means are multiplexed,
The cell combining means,
Code comparing means for comparing codes assigned to a plurality of partial cells to be inputted with each other and determining whether the division source cells of the partial cells are the same,
A control unit for controlling a cell restoration operation according to a comparison result of the code comparison unit;
A coupling timing correction buffer for storing the partial cells output from the respective partial cell switch means,
A cell restoration unit that collects partial cells read from the coupling timing correction buffer and restores the original cells;
A queue length comparing unit that compares the queue length information given to each partial cell, and a read control unit that controls a read operation of the coupling timing correction buffer according to a comparison result of the queue length and the code , An ATM switch, comprising: The ATM switch according to claim 1, wherein
When the result of comparison by the code comparing means does not match continuously for a specific number of times or more, resetting the queue buffers of the corresponding output routes provided in all of the partial cell switching means.
An ATM switch characterized by the above-mentioned . The ATM switch according to claim 1, wherein
As a result of the comparison by the code comparing means, when a plurality of codes that do not match are detected, the queue buffers of the corresponding output routes provided in all the partial cell switch means are reset. ATM switch . The ATM switch according to claim 1, wherein
The code assigning means and the queue length information assigning means write the code and the queue length information in a routing tag area provided in the partial cell.
An ATM switch characterized by the above-mentioned . The ATM switch according to claim 1 , wherein
The read control unit determines that the code in one partial cell is different from that of another partial cell by the code comparing means, and that the queue length of the partial cell having the different code by the queue length comparing means is smaller by one. If it is determined, the reading of the partial cells having different codes from the combined timing correction buffer is held, and other partial cells are discarded from the combined timing correction buffer.
An ATM switch characterized by the above-mentioned . The ATM switch according to claim 1, wherein
The read control unit determines that the code in one partial cell is different from the other partial cells by the code comparing unit, and that the queue length of the partial cell in which the code is different by the queue length comparing unit is larger by one. If determined, discarding the partial cell having the different sign from the combined timing correction buffer, and holding the reading of the other partial cells from the combined timing correction buffer.
An ATM switch characterized by the above-mentioned . A cell division unit that divides each of cells input from a plurality of input lines into a plurality of partial cells, and a plurality of partial cell switches that switch the divided partial cells based on destination information assigned to the partial cells; An asynchronous transfer mode (ATM) switch having a cell combiner for restoring the switched partial cell to the original cell and sending the restored partial cell to an output line;
A plurality of buffers for accumulating partial cells output from each of the plurality of partial cell switches;
From the information on the partial cells stored in the plurality of buffers, a timing shift detecting unit that detects a timing shift of the same partial cell as the division source,
A timing shift correction unit for correcting a timing shift of the partial cells having the same division source detected by the timing shift detection unit,
Cell restoration means for restoring the same partial cell corrected by the timing deviation correction means to the same partial cell as the original cell and outputting to the output line,
An ATM switch comprising:

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