JPH1168784A - Cell switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cell switch of a common buffer type in which abort priority control is conducted depending on outgoing lines and priority classes. SOLUTION: A 1st count means counts the number of cells stored in a common buffer memory 5 by an abort priority class and in the case that each count exceeds a threshold count decided respectively, when a cell of the priority class corresponding to the count is received newly from an incoming line, it is aborted. Furthermore, a 2nd count means counts number of cells stored in the common buffer memory 5 by an outgoing lines and by each priority class and in the case that each count exceeds a threshold count decided respectively, when a cell of the priority class corresponding to the count is received newly from an incoming line, it is aborted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to voice, data,
The present invention relates to a cell switch that relays cells in which various pieces of multimedia information such as images are blocked and exchanges them at high speed.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram of a conventional communication channel disclosed in, for example, Japanese Patent Laid-Open Publication No. 4-94237, "Priority Control Method in ATM Switching Communication Channel", and FIG. FIG. The ATM switching communication path has a plurality of incoming lines 10003 and a plurality of outgoing lines 10004, and a plurality of communication blocks 10001-1 to 10001-n for outputting cells entering from the incoming line 10003 to a desired outgoing line along a required path. And each of the communication blocks is provided with the number of incoming lines for each corresponding outgoing line (# 1 to #n) 10004, and a buffer unit 10 for avoiding cell collision.
002-1,. . . . . , 10002-m. A priority according to the discard characteristic of the cell is added to the header of each cell. Each buffer unit 10002 includes a buffer memory 10005, a cell accumulation amount measuring unit 10006 for measuring the cell accumulation amount in the buffer memory, and cell discarding units 10008, 10009, and 10010. In the cell accumulation amount measuring means 10006, the cell accumulation amount is
When a predetermined threshold is exceeded, the cell discarding means 10008, 10009, and 10010 discard cells with low priority.

[0003]

In the above-mentioned conventional system, the output buffer memory type is provided with a buffer memory corresponding to each outgoing line for each incoming line. However, as a buffer memory system of the cell switch, a plurality of outgoing lines are buffered. The common buffer memory type which uses the memory in common is advantageous because the use efficiency of the buffer memory is improved. However, the cell switch of the common buffer memory type differs in the way of holding the buffer memory from the above-described conventional example, so that the conventional discard control method (a method of performing discard control corresponding to the outgoing line) cannot be adopted.
Further, in the above conventional example, when the number of cells stored in the buffer memory exceeds the threshold, the cells of the low priority class are discarded. There was a problem that the possible number fluctuated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a cell switch according to the first invention has a discard priority class which determines the number of cells stored in a common buffer memory. A separate counting means is provided, and when each count value exceeds a predetermined threshold value, when a cell of a priority class corresponding to the count value is newly input from the incoming line, this is discarded. Means for counting the number of cells stored in the common buffer memory for each output line and for each priority class, and when each count value exceeds a threshold determined for each, When a cell corresponding to the outgoing line and the priority class is newly input from the incoming line, the counted value is discarded.

A cell switch according to a second aspect of the present invention comprises:
Means for counting the number of cells stored in the common buffer memory for each discard priority class, and when each count value exceeds a predetermined threshold value, the priority class corresponding to the count value To notify the outside of the cell switch that the cells are congested, and a means for counting the number of cells stored in the common buffer memory for each outgoing line and for each priority class. If the threshold exceeds a predetermined threshold value, the fact that the cell corresponding to the outgoing line and the priority class corresponds to the counted value is congested is notified to the outside of the cell switch.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a configuration diagram showing one embodiment of a cell switch according to the present invention. In FIG. 1, 11
Reference numerals 14 to 14 are input lines which are constituted by a data section and a header section including destination information thereof, and into which cells in which any of a plurality of service classes are set are inputted. In this embodiment, for simplicity of description, the number of service classes is two, that is, class 1 and class 2.

Outgoing lines 111 to 114 are used to output cells input from the incoming lines 11 to 14. In the present invention, it is not necessary to limit the number of incoming lines and outgoing lines, and it is possible to configure an arbitrary number of lines.
The number of incoming and outgoing lines is four.

Reference numeral 2 denotes a MUX for multiplexing cells input from the input lines 11 to 14, and reference numeral 3 denotes a header process for processing a cell header. Reference numeral 5 denotes a common buffer memory (hereinafter referred to as SBM) in which input cells are temporarily stored. Reference numeral 4 denotes write control for controlling writing of cells to the SBM 5; This is read control for controlling reading. Reference numeral 6 denotes an address queue for managing the address of the SBM 5 to which the cell has been written in correspondence with the outgoing lines 111 to 114; This is a discard control that performs discard priority control according to the priority class. Reference numeral 10 denotes a DMUX for separating cells read from the SBM 5.

The discard control 8 includes the following as shown in FIG. (1) SBM class 1 cell number counter 821 that counts the number of service class 1 cells in SBM 5 (2) SBM class 2 cell number counter 822 that counts the number of service class 2 cells in SBM 5 (3) SBM 5 SBM class 1 threshold register 8 for holding a threshold for the number of cells of service class 1
31 (4) SBM class 2 threshold register 8 holding a threshold for the number of cells of service class 2 in SBM 5
32 (5) Outgoing line 1 class 1 cell number counter 8511 to outgoing line 4 class 1 cell counter 8514 for counting the number of cells of service class 1 in SBM 5 for each destination corresponding to each of outgoing lines 111 to 114 (6) Outgoing line 1 class 2 cell number counter 8521 to outgoing line 4 class 2 cell number counter 8524 (counting the number of cells of service class 2 in SBM 5 for each destination corresponding to each of outgoing lines 111 to 114) 7) Outgoing line 1 class 1 threshold value register 8611 to outgoing line 4 class 1 for holding a threshold value for the number of cells of service class 1 in SBM 5 for each destination corresponding to each of outgoing lines 111 to 114 Threshold value register 8614 (8) Corresponding to each of the outgoing lines 111 to 114, the number of cells of the service class 2 in the SBM 5 for each destination is determined. Outgoing line 1 class 2 threshold value register 86211 to outgoing line 4 class 2 threshold value register 8624 (9) Comparator for comparing each cell counter with the value of the corresponding threshold value register 811-820

Here, it is assumed that the sum of the values of the SBM class 1 threshold register and the SBM class 2 threshold register is equal to the common buffer memory capacity of the cell switch. Outgoing line 1 class 1 threshold value register 8611 to outgoing line 4
The sum of each threshold in the class 1 threshold register 8614 need not be equal to the SBM class 1 threshold register,
The value may be larger than that of the SBM class 1 threshold register. Similarly, outgoing line 1 class 2 threshold value register 86
The sum of the threshold values of the 21 to outgoing line 4 class 2 threshold value register 8624 does not need to be equal to the SBM class 2 threshold value register, and may be a value larger than the SBM class 2 threshold value register.

Next, the operation will be described. FIG. 3 is an explanatory diagram showing the operation of this embodiment. Incoming lines 11-14
Are multiplexed by the MUX 2 and sent to the header processing unit 3. The header processing unit 3 determines a valid cell / empty cell based on the cell header, extracts a destination and a service class, sends the processing result information to the write control 4, and sends the cell to the SBM 5. When the cell discard instruction is not issued from the discard control unit 8 and the cell is a valid cell, the write control unit 4 extracts the unused address of the SBM 5 from the free address management unit 7 as shown in FIG. This address is sent to the SBM 5 and the address queue 6. The service class information of the cell is also sent to the address queue 6.

The cell transmitted from the header processing unit 3 is written to the address of the SBM 5 specified by the write control unit 4. In FIG. 3, a vacant address A is extracted from the vacant address management unit 7, and the cell 1 sent from the header processing unit 3 is written into the vacant address A. The address and service class information sent to the address queue 6 are written at the end of the outgoing line queue, which is the destination of the corresponding cell. For example, in FIG. 3, since the cell 1 is addressed to the outgoing line 111, the address A and the service class information class 1 are written at the end of the outgoing line 111 queue of the address queue 6.

The write controller 4 notifies the destination information and the service class of the cell written in the SBM 5. Thereby, the discard control unit 8 counts up the corresponding counter. For example, in the case of FIG. 3, since the destination of cell 1 is the outgoing line 111 and the service class is 1, the value of the SBM class 1 cell number counter 821 and the outgoing line 1 class 1 cell number counter 8511 is set to 1 Is added. The read control unit 9 reads the address and service class information at the head of each outgoing line corresponding queue of the address queue 6 as shown in FIG. The read address is notified to the SBM 5, and the cells corresponding to each outgoing line are read from the SBM 5 one by one.

If there is no address in each outgoing line corresponding queue of the address queue 6, there is no cell to be read from the SBM 5, and an empty cell is inserted. The address from which the cell has been read is set as a free address, and the free address management unit 7
To be reused. Further, the read control unit 9 transmits the destination information and the service class information of the cell read from the address queue 6 to the discard control unit 8. As a result, the discard control unit 8 counts down the corresponding counter by one.

For example, in the case of FIG. 4, an address B is read from the address queue 6 for the outgoing line 111, an address C is read for the outgoing line 112, and an address E is read for the outgoing line 114. In addition, there is no address at the head of the queue corresponding to the outgoing line 113, and no address is read for the outgoing line 113. These addresses are sent to SBM5,
Cell 2, corresponding to outgoing lines 111, 112, 114 from BM5
3 and 5 are read out, respectively.

Since an address to be read is not given to the outgoing line 113, an empty cell is inserted. The addresses B, C and E from which the cells have been read are released and sent to the vacant address management unit 7. The read control unit 9 notifies that the cell of the service class 1 has been read for the outgoing line 111, the cell of the service class 2 for the outgoing line 112, and the cell of the service class 2 for the outgoing line 114. So S
The value of the BM class 1 cell counter is counted down by one, and the value of the SBM class 2 cell counter is counted down by two. The output line 1 class 1 cell number counter, output line 2 class 2 cell number counter, and output line 4 class 2 cell number counter are each counted down one by one.

In this example, the address and the service class information are written in the address queue.
It is also possible for the address queue to manage addresses for each outgoing line and for each service class. Even in this case, the read control unit 9 can detect the service class of the cell written at the address read from the address queue.

The cells read from the SBM 5 are separated by the DMUX 10 as shown in FIG. 5 and output to each output line. In the cell read from the SBM 5 in FIG. 4, the cell 2 is output to the output line 111, the cell 3 is output to the output line 112, and the cell 5 is output to the cell 5 output line 114.

Next, the operation when cell discarding is performed will be described. The discarding control unit 8 compares the value of each counter provided in the discarding control unit 8 with the value of the corresponding threshold register by using a built-in comparator to determine the magnitude of the counter value and the threshold value. . As shown in FIG.
When the value of the BM class 1 cell number counter becomes larger than the value of the SBM class 1 threshold register, the discard control unit 8 discards all the service class 1 cells input from the incoming line. Instruct 4 According to this instruction, the write control unit 4 does not instruct the SBM 5 about the address of the cell of the service class 1, so that the cell is discarded without being written to the SBM 5.

Similarly, when the value of the SBM class 2 cell number counter becomes larger than the value of the SBM class 2 threshold register in the discard control unit 8, the discard control unit 8 sets the service class 2 input from the incoming line. The write control unit 4 is instructed to discard this cell. According to this instruction, the write control unit 4 does not instruct the SBM 5 on the address of the cell of the service class 2 so that the cell is
Is not written to and discarded.

As shown in FIG. 7, the value of the SBM class 1 cell number counter is smaller than the value of the SBM class 1 threshold value register, and the value of the outgoing line 1 class 1 cell counter is outgoing line 1 When the value becomes larger than the value of the class 1 threshold register, the discard control unit 8 instructs the write control unit 4 to discard the service class 1 cell addressed to the outgoing line 111 input from the incoming line. . By this instruction, outgoing line 1
The input cell of the service class 1 addressed to No. 11 is discarded without being written to the SBM 5.

The same applies to cells destined for other outgoing lines.
The value of the BM class 1 cell number counter is smaller than the value of the SBM class 1 threshold register, and the value of the outgoing line 2 class 1 cell counter is larger than the value of the outgoing line 2 class 1 threshold register. In the case, the input cell of the service class 1 addressed to the outgoing line 112 has the value of the SBM class 1 cell number counter smaller than the value of the SBM class 1 threshold register and the value of the outgoing line 3 class 1 cell number counter Is outgoing line 3
When the value is larger than the value of the class 1 threshold register, the input cell of the service class 1 addressed to the outgoing line 113 has a value of the SBM class 1 cell number counter smaller than the value of the SBM class 1 threshold register, and If the value of the outgoing line 4 class 1 cell number counter is larger than the value of the outgoing line 4 class 1 threshold value register, the service class 1 addressed to the outgoing line 114 is output.
Of input cells are discarded.

The same applies to the service class 2 in which the value of the SBM class 2 cell number counter is smaller than the value of the SBM class 2 threshold value register and the outgoing line 1
When the value of the class 2 cell number counter is larger than the value of the outgoing line 1 class 2 threshold register, the input cell of the service class 2 destined for the outgoing line 111 is changed to the SBM class 2 cell number counter of SBM class 2 If the value of the outgoing line 2 class 2 cell number counter is smaller than the value of the threshold value register and the value of the outgoing line 2 class 2 cell number counter is larger than the value of the outgoing line 2 class 2 threshold value register, the service class 2 If the input cell has a value of the SBM class 2 cell number counter smaller than the value of the SBM class 2 threshold register and the outgoing line 3
If the value of the class 2 cell number counter is larger than the value of the outgoing line 3 class 2 threshold value register, the input cell of the service class 2 destined for the outgoing line 113 has the SBM class 2 cell number counter value of SBM class 2 If the value of the output line 4 class 2 cell number counter is smaller than the value of the threshold value register and the value of the output line 4 class 2 cell number counter is larger than the value of the output line 4 class 2 threshold value register, the service class 2 Input cells are discarded.

Embodiment 2 FIG. FIG. 8 is a configuration diagram showing another embodiment of the cell switch according to the present invention. 1 are the same as those shown in FIG. 1, and the description is omitted here. 41 is a write control unit. Reference numeral 81 denotes a congestion notification control unit that notifies the congestion to the outside by the cell switch. The congestion notification control unit 81 includes the same counter and comparator as the discard control unit 8 shown in FIG.

Next, the operation will be described. Those having the same numbers as those in FIG. 1 perform the same operations as in the first embodiment. Write control unit 41
Controls the writing of the input cells to the common buffer memory based on the information sent from the header processing unit 3, as in the writing control unit 4. However, in the first embodiment, the write control unit 4 prevents the cells of the specified service class from being written into the SBM 5 by the discard instruction from the discard control unit 8. Is not given, so that this operation is not performed.

The congestion notification control section 81 notifies congestion to the outside. When the counter value is larger than the threshold value based on the comparison result of each comparator included in the congestion notification control unit 81, the congestion is notified. For example, when the value of the SBM class 1 cell number counter is larger than the value of the SBM class 1 threshold register, it notifies that the service class 1 cells are congested in the entire SBM.

The value of the SBM class 1 cell number counter is smaller than the value of the SBM class 1 threshold value register, and the value of the outgoing line 1 class 1 cell counter is outgoing line 1
If the value is larger than the value of the class 1 threshold value register, it notifies the outside that the cell of the service class 1 addressed to the outgoing line 111 is congested. The same applies to other service classes and other outgoing lines.

[0028]

According to the present invention, there is provided first counting means for counting the number of cells stored in the common buffer memory for each outgoing line and for each priority class. When each count value exceeds the threshold value determined for each, when a cell corresponding to the outgoing line and the priority class is newly input from the incoming line, the count value is discarded. This has the effect that cell discard control can be performed for each outgoing line and for each priority class.
A second counting means for counting the number of cells stored in the common buffer memory for each discard priority class;
If the count value counted by the counting means exceeds a predetermined threshold value, if a cell of a priority class corresponding to the count value is newly input from the incoming line, this is discarded. As a result, there is an effect that fluctuations in the storage amount of a cell of a certain priority class in the common buffer memory do not affect the storable amount of cells of another priority class.

According to another aspect of the present invention, there is provided a first counting means for counting the number of cells stored in the common buffer memory for each outgoing line and for each priority class, and the number is counted by the first counting means. When each of the counted values exceeds the threshold value determined for each, the output line and the priority class corresponding to the counted value are notified to the outside of the cell switch that a cell corresponding to the priority class is congested. Therefore, it is possible to perform discard control for each output line and priority class in the previous stage of the cell switch, or to perform flexible control such as selective accumulation, and further, the accumulated information is stored in the common buffer memory. A second counting means for counting the number of cells for each discard priority class, wherein each count value counted by the second counting means exceeds a threshold value determined for each of them. In this case, the fact that cells of the priority class corresponding to the count value are congested is notified to the outside of the cell switch. There is an effect that control can be performed before the switch so as not to affect the storable amount of cells of the priority class.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a cell switch according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a discard control unit 8 illustrated in FIG.

FIG. 3 is an explanatory diagram showing the operation of the first embodiment.

FIG. 4 is an explanatory diagram showing an operation of the first embodiment.

FIG. 5 is an explanatory diagram showing the operation of the first embodiment.

FIG. 6 is an explanatory diagram showing the operation of the first embodiment.

FIG. 7 is an explanatory diagram showing the operation of the first embodiment.

FIG. 8 is an explanatory diagram showing the operation of the second embodiment.

FIG. 9 is a configuration diagram of a conventional communication path (cell switch).

FIG. 10 is a diagram illustrating a configuration of a buffer unit in FIG. 9;

[Explanation of symbols]

 2 MUX 3 Header processing unit 4 Write control unit 5 Common buffer memory 6 Address queue 7 Free address management unit 8 Discard control unit 9 Read control unit 10 DMUX 11 to 14 Input line 41 Write control unit 81 Congestion notification control unit 111 to 114 Outgoing lines 811 to 820 Comparator 821 SBM class 1 cell number counter 822 SBM class 2 cell number counter 831 SBM class 1 threshold value register 832 SBM class 2 threshold value register 8511 Outgoing line 1 class 1 cell number counter 8512 Outgoing line 2 Class 1 cell number counter 8513 Outgoing line 3 class 2 cell number counter 8514 Outgoing line 4 class 3 cell number counter 8521 Outgoing line 1 class 2 cell number counter 8522 Outgoing line 2 class 2 cell number counter 8523 Outgoing line 3 class 2 cell number counter 8524 Outgoing line 4 class 2 cell number Counter 8611 Outgoing line 1 class 1 threshold register 8612 Outgoing line 2 class 1 threshold register 8613 Outgoing line 3 class 1 threshold register 8614 Outgoing line 4 class 1 threshold register 8621 Outgoing line 1 class 2 threshold value Register 8622 Outgoing line 2 class 2 threshold register 8623 Outgoing line 3 class 2 threshold register 8624 Outgoing line 4 class 2 threshold register 10001-1 to 10001-n Talk block memory 10006 Cell storage amount measuring means 10007 Read multiplex Control 10008 Cell discarding unit 1 10009 Cell discarding unit 2 10010 Cell discarding unit 310011 Buffer control unit

Claims (2)

[Claims] 1. A plurality of input lines, each of which comprises a data portion and a header portion including destination information thereof, and to which a cell to which one of a plurality of discarding priority classes is set is input, and a plurality of output lines to which the cell is output. A common buffer memory type cell switch comprising a line and outputting the cell input from any of the incoming lines to any of the outgoing lines according to the destination information, wherein the number of cells stored in the common buffer memory is Is provided for each of the discarding priority classes. If each count value counted by the first count means exceeds a threshold value determined for each, the count value When a cell of a corresponding priority class is newly inputted from the incoming line, the cell is discarded, and the number of cells stored in the common buffer memory is determined by the outgoing line and the priority class. A second counting means for separately counting, and when each of the counted values counted by the second counting means exceeds a threshold value determined for each, the outgoing line and the priority class are added to the counted value. 3. A cell switch comprising cell discarding means for discarding a new cell corresponding to the input line from the incoming line. 2. A plurality of incoming lines, each of which comprises a data portion and a header portion including destination information thereof, for inputting a cell to which one of a plurality of discard priority classes is set, and a plurality of outgoing lines to which the cell is output. A common buffer memory type cell switch comprising a line and outputting the cell input from any of the incoming lines to any of the outgoing lines according to the destination information, wherein the number of cells stored in the common buffer memory is Is provided for each of the discarding priority classes. If each count value counted by the first count means exceeds a threshold value determined for each, the count value A first congestion notification unit for notifying the outside of the cell switch that a cell of a corresponding priority class is congested, and the number of cells stored in a common buffer memory is determined by the outgoing line. And second counting means for counting for each priority class, and when each of the counted values counted by the second counting means exceeds a threshold value determined for each of them, the counting value is output. And a second congestion notification means for notifying the outside of the cell switch that a cell corresponding to the priority class is congested.