JP2009225304A - Switching method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a configuration and to improve a switching capability. <P>SOLUTION: In a switching method for outputting output signals in parallel, when a plurality of FIFOs 21-27 connected to input data transmission lines 31-37, and output transmission lines 61-64 being output destinations of output waiting signals stored in an auxiliary FIFO 28 connected to the FIFOs 21-27 in parallel are overlapped, an arbitration section 51 in a control circuit 11 outputs the highest-priority signal to the output transmission lines and transfers the lowest-priority signal to the auxiliary FIFO 28. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a switching method and a switching device that perform signal switching, and more particularly to a switching method, a switching device, and a communication system in the case where an input / output signal has a plurality of inputs and a plurality of outputs.

2. Description of the Related Art Conventionally, switching devices that switch a plurality of input signals to generate a plurality of outputs have been developed (for example, see Patent Document 1).
The switching device includes a plurality of FIFOs (First In First Out) arranged in parallel and receiving a plurality of input signals, and an arbitrating unit that arbitrates the input signals input to the FIFOs and outputs them in parallel.

When switching with a conventional switching device, the bus arbitration unit first looks at the status of all FIFOs, checks the data storage status in the FIFO and the data output destination, and arbitrates when the output destinations overlap. If there is no overlap, data is output from the FIFO.
If the data output destination overlaps with another FIFO and is waiting for data output due to arbitration, the data next to the output waiting data cannot be output even if the other FIFO and the output destination do not overlap. Cause the data to stay.

The retention of data in the switching device not only increases the data delay, but also increases the FIFO capacity for storing data.
Therefore, in the switching device, increasing the switching speed makes it possible to shorten the delay time and to reduce the capacity of a random access memory (RAM (Randam Access Memory)) for storing data, thereby obtaining an absolute effect.

  Conventionally, in order to increase the switching speed, a method of increasing the operation clock frequency or switching by doubling the bus width is generally used. In this case, there is a problem that the configuration is complicated and expensive, such as a very expensive device. In addition, there is a limit to increasing the frequency, and there is a limit to speeding up.

Japanese Patent Laid-Open No. 3-16348

  An object of the present invention is to improve the switching capability by simplifying the configuration.

According to the present invention, in the switching method of switching input signals input in parallel via a plurality of input transmission lines and outputting the output signals in parallel to a plurality of output transmission lines as output destinations, the input transmission lines When the output destinations of the output waiting signals stored in the plurality of transmission FIFOs connected to and the standby FIFOs connected in parallel to the respective transmission FIFOs overlap, the signal having the highest priority is sent to the output destination And a switching method characterized in that the signal having the lowest priority is transferred to the spare FIFO.
When the output destinations of the output waiting signals stored in the plurality of transmission FIFOs connected to each input transmission line and the standby FIFO connected in parallel to each transmission FIFO overlap, the signal having the highest priority Are output to the output destination, and the signal having the lowest priority is transferred to the spare FIFO.

Here, the transmission FIFO that outputs a signal to the output destination may be configured to have the lowest priority.
Further, the priority of the spare FIFO may be set higher than the priority of the FIFO that outputs a signal to the output destination.
Further, the priority of the spare FIFO may be set to be lower than that of the FIFO that outputs a signal to the output destination.

According to the present invention, in the switching device that switches input signals input in parallel through a plurality of input transmission lines and outputs the output signals in parallel to a plurality of output transmission lines as output destinations, A plurality of transmission FIFOs connected to the transmission line, a spare FIFO connected in parallel to each of the transmission FIFOs, and an output waiting signal stored in the transmission FIFO and the spare FIFO are selected and An arbitration unit that outputs to an output destination, and the arbitration unit preferentially outputs a signal having the highest priority when output destinations of output waiting signals stored in the FIFOs overlap. A switching device is provided that transfers the lowest signal to the spare FIFO.
When the output destinations of the output waiting signals stored in the FIFOs overlap each other, the arbitration unit preferentially outputs the signal having the highest priority and transfers the signal having the lowest priority to the standby FIFO.

Here, the arbitration unit may be configured to lower the priority of the FIFO that outputs a signal to the output destination.
The arbitration unit may be configured so that the priority of the spare FIFO is higher than the priority of the FIFO that outputs a signal to the output destination.
The arbitration unit may be configured to lower the priority of the spare FIFO next to the FIFO that outputs a signal to the output destination.

  The arbitration means has an output waiting signal stored in each of the FIFOs, the input unit of which is connected to all the FIFOs and the output unit of which is connected to one of the plurality of output transmission lines. A plurality of data reading means for selectively reading out and outputting to the output transmission line, the data reading means having the lowest priority of the FIFO that outputs a signal to the output transmission line, and the spare FIFO The priority may be set to be lower than that of the FIFO that outputs a signal to the output transmission line.

  According to the present invention, in the communication system including the switching device that switches the input signals input in parallel through the plurality of input transmission lines and outputs the output signals in parallel to the plurality of output transmission lines, the switching is performed. There is provided a communication system comprising the switching device according to any one of the above as a device.

According to the switching method of the present invention, the configuration can be simplified and the switching capability can be increased.
Further, according to the switching device of the present invention, it is possible to increase the switching capability by simplifying the configuration, and it is possible to construct a communication system having an increased switching capability by simplifying the configuration.
Further, according to the communication system according to the present invention, the configuration can be simplified and the switching capability can be increased.

Hereinafter, a switching method and a switching device according to an embodiment of the present invention will be described. In the drawings, the same parts are denoted by the same reference numerals.
FIG. 1 is a schematic block diagram of a switching device used in a switching method according to an embodiment of the present invention.

  In FIG. 1, the switching device is connected to a plurality of transmission lines to which a plurality of input data is input in parallel, and a plurality of FIFOs (First In First Out) 1 to m and a plurality of FIFOs 1 for transmission arranged in parallel. And a control unit 11 that arbitrates the outputs of the spare FIFO On and FIFOs 1 to m connected in parallel with .about.m and outputs a plurality of output data in parallel. The FIFOs 1 to n can be configured using a random access memory (RAM) in the switching device.

The input data is stored in the FIFOs 1 to m connected to the respective transmission lines and waits for output through the control unit 11. The control unit 11 includes an arbitration unit therein, performs arbitration by determining the status of each of the FIFOs 1 to m, reads data from the FIFOs 1 to m, and outputs the data to a predetermined transmission line.
In the embodiment of the present invention, in a switching device in communication of burst data such as packets, the delay due to switching is reduced while suppressing the capacity of the RAM as much as possible.

FIG. 2 is a detailed block diagram of the switching device used in the switching method according to the embodiment of the present invention.
In FIG. 2, the switching device includes a spare FIFO 28 in addition to the control unit 11 and a plurality of transmission FIFOs 21 to 27 arranged in parallel for storing input data input in parallel. The control unit 11 includes an arbitration unit 51.

  The spare FIFO 28 performs data transfer from the FIFO waiting for data output by the arbitration of the arbitration unit 51, and the FIFO 28 waits for data output from the FIFOn by arbitration. The FIFOs 21 to 27 can process the next data by transferring the output waiting data to the FIFO 28. Thereby, the delay in the switching device can be suppressed, and the increase in the RAM capacity can also be suppressed.

  More specifically, in FIG. 2, input data input from the data transmission lines 31 to 37 is stored in the FIFOs 21 to 27. The arbitration unit 51 checks the data storage status of the FIFOs of the FIFOs 21 to 28 and the data output destination, and performs arbitration if there are FIFOs with overlapping output destinations.

On the other hand, if the output destinations do not overlap, output is performed as it is. If the output destinations overlap, data is output from the FIFO with the highest priority, and transfer from the FIFO with the lowest priority (excluding the FIFO 28) to the spare FIFO 28 is performed.
Data is input from the signal transmission lines 31 to 37. The FIFOs 21 to 27 store the input data, respectively. The arbitration unit 51 arbitrates data output from the FIFOs 21 to 28.

FIG. 3 is a detailed block diagram of the arbitration unit 51. The arbitration unit 51 includes a plurality of data reading units 71 to 74 arranged in parallel, and is configured to arbitrate output to the output-side data transmission lines 61 to 64 connected thereto.
As described above, the arbitration unit 51 has an input unit connected to all the transmission and backup FIFOs 21 to 28 and an output unit connected to one of the plurality of output transmission lines 61 to 64. A plurality of data reading units 71 to 74 for selectively reading out the output waiting signals stored in the FIFOs 21 to 28 and outputting the signals to the corresponding output transmission lines are provided.

Although details of the operation will be described later, the data reading unit 71 sets the priority of the FIFOs 21 to 27 that output signals to the corresponding output transmission line 61 to the lowest level, and sets the priority of the spare FIFO 28 to the output transmission line 61. It functions to lower the priority next to the FIFO that outputs the signal.
1 to 3, the control unit 11 constitutes a control unit, the arbitration unit 51 constitutes an arbitration unit, and the data reading units 71 to 74 each constitute a data reading unit.
FIG. 4 is a flowchart showing processing of the control unit 11 including the arbitration unit 51.

Hereinafter, the switching method and the switching device according to the present embodiment will be described with reference to FIGS.
The data reading unit 71 in the arbitration unit 51 confirms the data storage status of the FIFOs 21 to 28 (step S401 in FIG. 4) and confirms whether the data output destination is the data transmission line 61 (step S402).

Next, the data reading unit 71 determines whether or not arbitration is necessary (step S403). That is, when only one FIFO is waiting for output to the data transmission line 61, the data reading unit 71 determines that arbitration is not necessary, reads data from the FIFO, and outputs the data to the data transmission line 61. (Steps S403 and S405).
On the other hand, when there are a plurality of FIFOs waiting for output to the data transmission line 61, the data reading unit 71 determines that arbitration is necessary and performs arbitration (step S403).

In the arbitration, the data reading unit 71 outputs data to the data transfer line 61 from the FIFO with the highest priority, and transfers data from the FIFO with the lowest priority excluding the spare FIFO 28 to the spare FIFO 28 ( Step S404).
The data reading unit 71 sets the priority of the FIFO that has output data to the data transmission line 61 to the lowest, and sets the FIFO 28 to the next lowest priority.

  As a method for determining the priority, a priority can be given to each FIFO, and input data stored in a FIFO with a high priority can be preferentially output to an output destination. Alternatively, each FIFO may be prioritized and stored in the FIFO according to the priority of the input data, and arbitration may be performed based on the priority of each FIFO. Further, it is possible to appropriately set such that priority is given to input data, and arbitration is performed based on the priority given to each input data at the time of arbitration.

In processing step S402, when there is no data to the data transmission line 61, it returns to processing step S401.
Further, when any of the data reading units 71 to 74 outputs a signal waiting for output stored in the spare FIFO 28 to any of the data transmission lines 61 to 64 corresponding to the data reading units 71 to 74, The standby FIFO 28 is in a state where no output waiting signal is stored. Thereafter, the data reading unit 71 processes again as described above.

  As described above, in the switching method and switching device according to the present embodiment, the arbitration unit 51 in the control circuit 11 includes the plurality of FIFOs 21 to 27 and the FIFOs 21 to 27 connected to the input data transmission lines 31 to 37. When the output transmission lines 61 to 64 that are output destinations of the output waiting signals stored in the spare FIFO 28 connected in parallel are overlapped, the signal having the highest priority is output to the output transmission line and the priority is lowest. The signal is transferred to the spare FIFO 28.

Therefore, since it can be configured only by adding a few spare FIFOs, it is possible to increase the switching capability with a simple configuration while minimizing the increase in RAM capacity.
Further, a flexible configuration is possible according to the FIFO (RAM) capacity that the switching device can have, and the switching capability can be increased according to the number of spare FIFOs.

Further, by using the switching device according to the present embodiment, it is possible to construct a communication system with a simple configuration and high switching capability.
In this embodiment, one spare FIFO is provided. However, by increasing the number of spare FIFOs according to the system, the switching capability can be further improved and the delay can be reduced. It is possible to have the flexibility to perform a circuit configuration according to the system.

  That is, in this embodiment, the data reading unit 71 is configured to add one FIFO 28 whose priority can be controlled. However, each data reading unit 71 to 74 can read each FIFO 28 whose priority can be controlled. The data reading units may be configured to correspond to the units 71 to 74 so that each data reading unit performs the same operation as the data reading unit 71 described above. As a result, the switching capability can be further increased.

Further, each of the data reading units 71 to 74 may be configured to perform the arbitration process as described above by sharing one FIFO 28.
Further, the present embodiment can be applied to all communication devices that perform data switching, such as ATM (Asynchronous Transfer Mode) and switching devices for packet communication such as IP.

  Further, the present embodiment can be used for all communication devices that require switching of data having inputs from a plurality of lines.

  The present invention can be used for all communication devices and communication systems that require switching of data having inputs from a plurality of lines.

1 is a schematic block diagram of a switching device used in a switching method according to an embodiment of the present invention. It is a detailed block diagram of the switching apparatus used for the switching method which concerns on embodiment of this invention. It is a partial block diagram of the switching apparatus used for the switching method which concerns on embodiment of this invention. It is a flowchart for demonstrating operation | movement of embodiment of this invention.

Explanation of symbols

1-m, 21-27 ... FIFO
n, 28 ... Reserve FIFO
11: Control unit 51: Arbitration unit 71-74 ... Data reading unit

Claims (10)

In a switching method of switching input signals input in parallel via a plurality of input transmission lines and outputting the output signals in parallel to a plurality of output transmission lines as output destinations,
When output destinations of output waiting signals stored in a plurality of transmission FIFOs connected to each input transmission line and a spare FIFO connected in parallel to each transmission FIFO overlap, the highest priority is given. A switching method characterized by outputting a signal to the output destination and transferring a signal having the lowest priority to the spare FIFO.   2. The switching method according to claim 1, wherein a priority of a transmission FIFO that outputs a signal to the output destination is set to the lowest.   3. The switching method according to claim 2, wherein the priority of the spare FIFO is set higher than the priority of the FIFO that outputs a signal to the output destination.   4. The switching method according to claim 3, wherein the priority of the spare FIFO is made lower than that of the FIFO that outputs a signal to the output destination. In a switching device that switches input signals input in parallel via a plurality of input transmission lines and outputs output signals in parallel to a plurality of output transmission lines that are output destinations.
Select a plurality of transmission FIFOs connected to each of the input transmission lines, a backup FIFO connected in parallel to each of the transmission FIFOs, and an output waiting signal stored in the transmission FIFO and the backup FIFO And arbitration means for outputting to the output destination,
The arbitration means preferentially outputs a signal having the highest priority when the output destination of the output waiting signal stored in each FIFO overlaps, and transfers the signal having the lowest priority to the spare FIFO. A switching device characterized by:   6. The switching device according to claim 5, wherein the arbitration unit sets the priority of the FIFO that outputs a signal to the output destination to the lowest.   7. The switching device according to claim 6, wherein the arbitration unit sets the priority of the spare FIFO higher than the priority of the FIFO that outputs a signal to the output destination.   8. The switching apparatus according to claim 7, wherein the arbitrating unit lowers the priority of the spare FIFO next to the FIFO that outputs a signal to the output destination. The arbitration means selects an output waiting signal stored in each of the FIFOs with its input connected to all the FIFOs and its output connected to one of the plurality of output transmission lines. A plurality of data reading means for reading and outputting to the output transmission line automatically,
The data reading means sets the priority of the FIFO that outputs a signal to the output transmission line to the lowest level, and sets the priority of the spare FIFO to the priority next to the FIFO that outputs the signal to the output transmission line. The switching device according to claim 8, wherein the switching device is lowered. In a communication system including a switching device that switches input signals input in parallel via a plurality of input transmission lines and outputs output signals in parallel to the plurality of output transmission lines.
A communication system comprising the switching device according to any one of claims 5 to 9 as the switching device.

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