JPH10276214A - Asynchronous transfer mode switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an asynchronous transfer mode switch where quality of cells with higher priority is warranted by exchanging cells while distinguishing cells with higher priority and emphasized transmission quality from cells with lower priority. SOLUTION: A user network interface(UNI) section 12a receiving cells from a terminal 11a adds a cell type identification bit denoting a cell type to the cell or the like, a selector section 13a provides an output of the cell to a granted traffic (G) cell switch section 14 or a best effort traffic (B) cell switch section 15 based on the cell type identification bit and the switch section 14 or 15 receiving a corresponding cell exchanges the cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asynchronous transfer mode switch for receiving cells having priority-related information and exchanging the cells. The present invention relates to an asynchronous transfer mode switch for exchanging a low-priority cell while distinguishing it from another, thereby guaranteeing the cell quality of a high-priority cell.

[0002]

2. Description of the Related Art Conventionally, an asynchronous transfer mode (hereinafter referred to as "ATM (Asynchronous Transfer
r Mode) ". ) The switch is known and this A
In the TM switch, the transfer process is speeded up by a transfer process using hardware using cells of fixed-length packets and a simplified protocol that does not perform flow control and transmission confirmation.

FIG. 8 is a diagram showing an example of the configuration of a conventional ATM switch.

As shown in FIG. 8, a conventional ATM switch 80 includes a user network interface unit (hereinafter referred to as a "UNI (Us)" corresponding to each of terminals 81a to 81f.
er Network Interface) section. ) 83a-83f
And a switch unit 82 for exchanging cells which are fixed-length packets of 53 bytes.

For example, when the terminal 81a transmits a cell to the terminal 81f, a VP (Virtual Path)
Alternatively, the UNI unit 83a of the ATM switch 80 receives the cell via a VC (Virtual Channel).

[0006] Then, the switch unit 82 having received the cell determines which transmission path VP / VC to replace the cell from the VP / VC according to a predetermined table, and determines the VP / VC of the determined transmission path. / VC is exchanged. Thus, this cell is output to the terminal 81f via the UNI unit 83f.

As described above, in the conventional ATM switch 80, processes such as flow control and delivery confirmation are left to the upper layer protocol on the terminal side, and the ATM switch 80 itself performs cell transfer processing by hardware, That speed has been realized.

[0008] However, among the cells handled by the ATM switch, a cell having a high priority and a high transmission quality (hereinafter referred to as a "G-cell (Guaranted Traffic)").
And a cell having a lower priority (hereinafter referred to as “B-cell (Best-Effort Tr
affic). )), Treating these cells in exactly the same way would result in a decrease in the cell quality of the G-cell.

[0009]

As described above, in the conventional ATM switch, the G-cell is exchanged without distinguishing it from the B-cell, so that the cell quality of the G-cell is guaranteed. Therefore, there is a problem that the user's needs relating to cell quality cannot be satisfied.

Accordingly, the present invention solves the above-mentioned problems, and replaces cells having high priority and transmission quality with distinction from cells having low priority, thereby guaranteeing the cell quality of cells having high priority. It is an object of the present invention to provide an asynchronous transfer mode switch.

[0011]

According to a first aspect of the present invention, there is provided an asynchronous transfer mode switch for receiving a cell having priority information and exchanging the cell. First switching means for switching a high-priority cell, second switching means for switching a low-priority cell, and first switching for replacing the cell based on information on the priority of the cell Selecting means for selecting the means or the second switching means and outputting the cell to the selected switching means.

[0012] In a second aspect of the present invention, the selection means includes: identification information providing means for providing identification information corresponding to the information relating to the priority to a cell; and identification information provided by the identification information providing means. Output means for outputting cells to the first switching means or the second switching means.

[0013] In a third aspect of the present invention, a cell is received from the first switching means and the second switching means, and the identification information given by the identification information giving means is removed from the received cell to address the destination terminal. And a transmitting means for transmitting the cell.

According to a fourth aspect of the present invention, the transmission unit includes a storage unit for temporarily storing cells received from the second switching unit, and the transmission unit does not process the cells received from the first switching unit. Only the cells temporarily stored in the storage means are processed.

According to a fifth aspect of the present invention, the selecting means assigns to the cell first identification information indicating whether or not a redundant system is configured and second identification information corresponding to the information relating to the priority. A cell to the first or second switching means based on the first and second identification information provided by the first and second switching means. And output means for performing the operation.

According to a sixth aspect of the present invention, the output means includes: when the first identification information indicates a configuration of a redundant system, the output means outputs to both the first exchange means and the second exchange means; Outputting a cell, and when the first identification information does not indicate the configuration of the redundant system, outputs the cell to one of the first exchange means or the second exchange means based on the second identification information. Outputting a cell.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an ATM used in the first embodiment.
FIG. 2 is a block diagram illustrating a configuration of a switch.

The ATM switch 10 shown in FIG. 1 is characterized in that two types of switch units for exchanging cells are provided.

That is, G-cells having high priority and transmission quality are emphasized are exchanged by the G-cell switch unit 14, and B-cells having low priority are exchanged by the B-cell switch unit 15. It is configured to do.

The UNI units 12a to 12f and the selector unit 13a correspond to the terminals 11a to 11f, respectively.
To 13f, and the terminals 11a to 11f, UN
The I units 12a to 12f and the selector units 13a to 13f
Each has a similar function and configuration.

Here, for convenience of explanation, the terminal 11a
Transmits a cell to the terminal 11f,
The function of each unit will be described sequentially according to the time series.

When a cell is received from the terminal 11a, the UNI unit 12a processes the physical layer on the communication protocol, synchronizes the cells, and performs OAM (Op
eration administration and maintenance), and additional information required for selection of the G-cell switch unit 14 or the B-cell switch unit 15 and exchange processing of each switch unit 14 or 15 are transmitted to the cell. Add to

The selector 13a is provided with the UNI 12a.
Is a processing unit that determines whether the cell received from is a G-cell or a B-cell, and selectively outputs the cell to the corresponding switch unit 14 or 15.

The G-cell switch section 14 is a switch section dedicated to G-cells that exchanges only G-cells having high priority and transmission quality is important, and a B-cell switch section 15.
Is a switch unit dedicated to B-cells having a low priority.

The selector unit 13f is a processing unit that outputs the cell received from the G-cell switch unit 14 or the B-cell switch unit 15 to the corresponding UNI unit 12f.

The selector 13f outputs the G-cell received from the G-cell switch 14 to the UNI 12f with priority over the B-cell received from the B-cell switch 15.

That is, the B-cell is temporarily stored in a buffer (not shown) provided inside the selector 13f, and is output to the UNI unit 12f only when there is no G-cell. Therefore, with respect to such a G-cell, transmission delay due to the presence of the B-cell can be reduced.

The UNI unit 12f receives the G-cell or the B-cell from the selector unit 13f, performs a physical layer process on a communication protocol, and outputs the cell to the terminal 11f.

As described above, in the ATM switch 10 having the above configuration, not all the cells are exchanged by only one switch unit, but a G-cell having a high priority and a B-cell having a low priority are different from each other. Since the switching is performed using the dedicated switch units 14 and 15, cell collision inside the ATM switch 10 can be suppressed, and the cell discard rate can be reduced.

Here, the terminal 11a is connected to the terminal 11f.
The function of each unit has been described by taking up the case where a cell is transmitted to each other, but the UNI units 12a to 12f
a and 12f, and each of the selectors 13a to 13f is provided with the selectors 13a and 13f.
f has both functions.

Next, the cell format of the G-cell and the B-cell will be described.

FIG. 2 is a diagram showing a format of a cell handled by the ATM switch 10 shown in FIG.

As shown in FIG. 2, this cell is a fixed-length cell (hereinafter, referred to as a "standard cell") 23 of 53 bytes, in which output port designation data 21 indicating destination information and a cell type identification bit 22 are provided. Is added to the format.

That is, when the UNI unit 12a receives a cell from the terminal 11a, the received cell is only the standard cell 23. However, the UNI unit 12a stores the output port designation data 21 for internal processing in the standard cell.
And a cell type identification bit 22 are added.

The output port designation data 21 is destination information required when the G-cell switch unit 14 or the B-cell switch unit 15 exchanges cells.

The cell type identification bit 22 is a bit indicating whether the received cell is a G-cell or a B-cell. For example, when the received cell is a G-cell, the cell type identification bit '1' is assigned to 22 and '0' is assigned if the cell is a B-cell.

The selector unit 13a shown in FIG.
The cell is referred to as G-
It is determined to output to either the cell switch unit 14 or the B-cell switch unit 15.

As described above, in the cell used in the first embodiment, the cell type information bit 22 is provided in the additional information of the standard cell 23, and the G-cell and the B-cell are determined by the cell type information bit 22. Distinction.

Next, the configuration of the UNI unit 12a for setting the cell type information bit 22 will be described.

FIG. 3 is a diagram showing a detailed configuration of the UNI section 12a shown in FIG.

As shown in FIG. 3, the UNI unit 12a
Is a PHY that performs physical layer processing on the communication protocol
It comprises a processing section 31, a cell synchronization section 32 for synchronizing cells, an OAM processing section 33 for performing fault management and the like, and a cell format conversion section 34 for performing cell format conversion.

Here, the cell format conversion unit 34
Performs a process of adding or deleting the output port designation data 21 and the cell type identification bit 22 to the standard cell 23 shown in FIG.

For example, the UNI unit 12a is connected to the terminal 11a
, The PHY processing unit 31 first performs the processing of the physical layer, and then the cell synchronization unit 32
Synchronizes the cells, and the OAM processing unit 33 performs a fault management process as necessary.

The cell format conversion unit 34
It is determined whether the received cell is a G-cell or a B-cell, and a bit corresponding to the determined cell type is added to the standard cell as a cell type identification bit.

Next, the processing procedure of the ATM switch 10 shown in FIG. 1 will be described. However, here, the terminal 11
Assume that a transmits a cell to terminal 11f.

FIG. 4 is a flowchart showing a processing procedure of the ATM switch 10 shown in FIG.

As shown in FIG. 4, this ATM switch 1
If the UNI unit 12a receives a cell from the terminal 11a (step 401), it checks whether the received cell is a G-cell or a B-cell (step 402).
A bit corresponding to the confirmed type is added to the cell as a cell type identification bit (step 403), and the selector 13
output to a.

Next, the selector unit 1 receiving this cell
In 3a, when the cell type identification bit indicates a G-cell, the cell is output to the G-cell switch unit 14. When the cell type identification bit indicates a B-cell, the cell is set to B-cell. -Output to the cell switch unit 15 (step 404).

Then, the G-cell switch unit 14 or the B-cell switch unit 15 receiving the cell from the selector unit 13c performs a cell exchange process and outputs the cell to the corresponding selector unit 13f (step 405). , 40
6).

Next, the selector 13f receiving the cell
Outputs a cell to the corresponding UNI unit 12f. In addition,
The UNI unit 12f performs priority processing of the G-cell, and gives priority to the G-cell over the B-cell to the UNI unit 12f.
Output to f.

Then, the UNI unit 1 receiving this cell
After removing additional data such as a cell type identification bit from the cell (step 407), 2f outputs the corresponding cell to the destination terminal 11f (step 408).

As described above, in the ATM switch 10, the high priority cell and the low priority cell are exchanged by different switch units.

As described above, in the first embodiment, the UNI unit 12a receiving a cell from the terminal 11a
Adds a cell type identification bit or the like indicating the cell type to the received cell, and the selector unit 13a switches the cell based on the cell type identification bit to the G-cell switch unit 14.
Alternatively, the G-cell switch unit 14 or the B-cell switch unit 15 that outputs the data to one of the B-cell switch units 15 and receives the corresponding cell is configured to exchange cells. Cell collision at the same time, and the cell discard rate can be reduced.

Further, in the first embodiment, the selector 13f processes the G-cell preferentially, and outputs the B-cell to the UNI 12f only when there is no G-cell. , B-cell can be processed with high priority.

In the ATM switch 10 used in the first embodiment, which of the G-cell switch unit 14 and the B-cell switch unit 15 performs the exchange processing depends on each priority. Although the switching is performed by the selector unit, a redundant system can be configured using the ATM switch 10.

Next, a description will be given of a case where the ATM switch 10 is used to form a redundant system.

FIG. 5 is a diagram showing a configuration when the ATM switch 10 shown in FIG. 1 operates as a parallel redundancy system.

As shown in FIG. 5, this ATM switch 5
0 has the same basic configuration as the ATM switch 10 shown in FIG.
Only the functions of 3a to 53f are different.

The primary system switch unit 54
The secondary system switch unit 55 corresponds to the G-cell switch unit 14 shown in FIG.
Corresponding to

Here, the UNI units 12a to 12 shown in FIG.
f, a cell type identification bit indicating the type of G-cell or B-cell is added to the standard cell.
In the NI units 52a to 52f, a redundancy identification bit indicating the presence or absence of the redundancy processing is added to the standard cell.

FIG. 6 is a diagram showing a format of a cell handled by the ATM switch 50 shown in FIG.

As shown in FIG. 6, this cell has a cell format in which output port designation data 21 indicating destination information and a redundancy type identification bit 61 are added to a standard cell 23 of 53 bytes.

That is, the UNI units 52 a to 52 f add the output port designation data 21 for internal processing and the redundancy identification bit 61 to the standard cell 23.

Specifically, the primary switch unit 5
In the case where the cell is exchanged by using only the redundancy identification bit 6,
1 is set to '0', and when cells are exchanged using both the primary system switch unit 54 and the secondary system switch unit 55 in parallel, the redundancy identification bit 61 is set to '1'.
And

For this reason, the selector sections 53a to 53f
When such a cell is received from the UNI units 52a to 52f, the redundant identification bit 61 added to the cell is confirmed. If the redundant identification bit 61 is "0", the cell is transmitted to the primary system switch unit 54. Output. On the other hand, if the redundancy identification bit 61 is “1”, the cell is output to the primary switch unit 54 and the secondary switch unit 55.

When a cell is output to both of the switches 54 and 55, a process of discarding one of the cells is required in the selector on the destination side which receives the cells from the switches 54 and 55.

As described above, by using the ATM switch 50 having the above configuration, it is possible to perform redundancy switching using the primary system switch unit 54 and the secondary system switch unit 55.

Since the ATM switch 50 has exactly the same basic configuration as the ATM switch 10 shown in FIG. 1, it takes in the priority processing function of the ATM switch 10 and performs the priority processing and the switching processing of the redundant system. You can do it too.

Specifically, when the UNI units 52a to 52f receive a cell from the corresponding terminal, as shown in FIG. 7, both the redundant identification bit 61 and the cell type identification bit 22 are assigned to the cell. Add.

Then, the cells are transferred to the UNI units 52a-52.
The selectors 53a to 53f received from the first node confirm the redundancy identification bit 61, and if the redundancy identification bit 61 is "1", output the cell to both the switch units 54 and 55.

On the other hand, the redundant identification bit 61
Is "0", the cell type identification bit 22 is further confirmed. If the cell type identification bit 22 is "1", the cell is regarded as a G-cell and output to the primary switch unit 54, If the cell type identification bit 22 is “0”, the cell is regarded as a B-cell and output to the secondary switch unit 55.

As described above, in the second embodiment, not only the priority processing using the two switch units but also the switch unit is applied to the redundancy processing. Can be increased.

In the first and second embodiments, the case where two switch units are used has been described. However, the present invention is not limited to this, and three or more switch units may be provided. It is possible. However, in this case, it is necessary to increase the number of cell type identification bits in accordance with the number of switch units.

[0075]

As described in detail above, the present invention provides
A first switching unit for exchanging cells with high priority and a second exchanging unit for exchanging cells with low priority are provided, and the cells should be exchanged based on information on the priority of the cells. Selecting the first exchange means or the second exchange means,
Since the cell is configured to be output to the selected switching means, cell collision inside the asynchronous transfer mode switch is suppressed to reduce the cell discard rate, thereby guaranteeing the transmission quality of high priority cells. It is possible to do.

Further, according to the present invention, the identification information corresponding to the information relating to the priority is assigned to the cell, and the cell is transmitted to the first exchange means or the second exchange means based on the assigned identification information. Since output is configured, it is possible to quickly and easily select an exchange unit for exchanging cells.

Further, the present invention provides a first exchange means and a second exchange means.
Receiving the cell from the exchange means, removing the identification information from the received cell and sending the cell to the destination terminal, temporarily storing the cell received from the second exchange means,
Since the cells temporarily stored in the storage unit are processed only when the cells received from the first switching unit are not processed, it is possible to reduce the processing delay of the cells with high priority.

Further, according to the present invention, the first identification information indicating whether or not to constitute a redundant system and the second identification information corresponding to the information relating to the priority are assigned to the cell, and the assigned first identification information is assigned to the cell. Since the cell is configured to be output to the first switching unit or the second switching unit based on the identification information and the second identification information, it can be diverted to a redundant system depending on the situation.

Further, according to the present invention, when the first identification information indicates the configuration of the redundant system, the cell is output to both the first switching unit and the switching unit, and the first identification information is output. When the configuration of the redundant system is not shown, the cell is output to one of the first switching unit and the second switching unit based on the second identification information. In addition to the above, it is possible to configure a bypass route when a failure occurs in the first switching unit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an ATM switch used in a first embodiment.

FIG. 2 is a diagram showing a format of a cell handled by the ATM switch shown in FIG. 1;

FIG. 3 is a diagram showing a detailed configuration of a UNI unit shown in FIG. 1;

FIG. 4 is a flowchart showing a processing procedure of the ATM switch shown in FIG. 1;

FIG. 5 is a diagram showing a configuration when the ATM switch shown in FIG. 1 operates as a parallel redundant system;

FIG. 6 is a diagram showing a format of a cell handled by the ATM switch shown in FIG. 5;

FIG. 7 is a diagram showing a cell format when the ATM switch shown in FIG. 5 has both a priority processing function and a redundant system switching function.

FIG. 8 is a diagram showing an example of the configuration of a conventional ATM switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ATM switch 11a-11f Terminal 12a-12f UNI part 13a-13f Selector part 14 G-cell switch part 15 B-cell switch part 21 Output port designation data 22 Cell type identification bit 23 Standard cell 31 PHY processing part 32 cell Synchronization unit 33 OAM processing unit 34 Cell format conversion unit 50 ATM switch 52a-52f UNI unit 53a-53f Selector unit 54 Primary system switch unit 55 Secondary system switch unit 61 Redundancy identification bit 80 ATM switch 81a-81f Terminal 82 Switch unit 83a- 83f UNI section

Claims (6)

[Claims] 1. An asynchronous transfer mode switch for receiving a cell having information relating to a priority and exchanging the cell, a first exchanging means for exchanging a high priority cell, and a low exchanging means for a low priority cell A second switching unit for performing a switching process on the cell, and selecting a first switching unit or a second switching unit for replacing the cell based on information on the priority of the cell,
An asynchronous transfer mode switch, comprising: selecting means for outputting the cell to the selected switching means. 2. The information processing apparatus according to claim 1, wherein the selection unit is configured to provide identification information corresponding to the information relating to the priority to a cell, and the first information based on the identification information provided by the identification information providing unit. 2. An asynchronous transfer mode switch according to claim 1, further comprising an output unit for outputting a cell to said switching unit or said second switching unit. 3. A cell is received from the first switching means and the second switching means, the identification information provided by the identification information providing means is removed from the received cell, and the cell is transmitted to a destination terminal. 3. The asynchronous transfer mode switch according to claim 2, further comprising sending means. 4. The transmission means comprises a storage means for temporarily storing cells received from the second switching means, and the storage means only when the cells received from the first switching means are not processed. 4. The asynchronous transfer mode switch according to claim 3, wherein the cell temporarily stored in the asynchronous transfer mode switch is processed. 5. The identification means for assigning, to a cell, first identification information indicating whether or not to constitute a redundant system and second identification information corresponding to the information related to the priority. Output means for outputting a cell to the first switching means or the second switching means based on the first identification information and the second identification information given by the identification information giving means. The asynchronous transfer mode switch according to claim 1, wherein 6. The output unit outputs a cell to both the first switching unit and the second switching unit when the first identification information indicates a configuration of a redundant system. If the first identification information does not indicate the configuration of the redundant system, the first identification information is set based on the second identification information.
6. The asynchronous transfer mode switch according to claim 5, wherein a cell is output to one of said switching means and said second switching means.