JP2002077259A - Reception system switching device, its method and its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reception system switching device capable of executing switching without hit using a simpler constitution. SOLUTION: This device is provided with a 0-system receiving part 91 for receiving data transmitted successively from an external device; a 1 system for receiving part 92 for receiving data from the external device through a path different from the route through which the data are received by the 0-system receiving part 91; a selecting part 101 connected to either the 0-system receiving part 91 or the 1-system receiving part 92 for receiving the data from the destination of connection, and for outputting the data; and a 0-system switching control part 102 and a 1-system switching control part 103 for detecting the need for switching the destination of acquisition of data to be used for information processing from the present receiving means of the 0-system receiving part 91 and the 1-system receiving part 92 to the other receiving means, for instructing the stoppage of data transmission to the external device, for allowing the selecting part 101 to switch the receiving means to the destination of connection to the other receiving means, and to output the data, after all the already transmitted data no longer exist on the path, until the selecting and outputting means, and for instructing the start of data transmission to the external device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention utilizes data received from one of two reception systems for information processing, discards data received from the other reception system, and The present invention relates to a technique for changing the relationship between use and destruction during information processing as necessary.

[0002]

2. Description of the Related Art Conventionally, two reception systems, a main system and a backup system, provided for improving the reliability of data reception,
When the same data is received in parallel and only the data received from one of the receiving systems is used for post-reception processing, the receiving system that is receiving the used data uses If it becomes impossible, switch to using data received from the other reception system without any problem so that duplication or omission of the data being used does not occur (hereinafter referred to as “
This is referred to as "non-stop switching". ) As a device, there is a reception system switching device.

The STM (Synchronous) will be described below.
Transfer Mode) and ATM (Asynch)
A conventional reception system switching device will be described by taking a reception system switching device used in a system for storing data such as a Robust Transfer Mode (packet) in a packet and transmitting the packet. FIG. 5 is a block diagram of a receiving system switching device 500 in a conventional ATM.

The receiving system switching device 500 has two receiving systems, system 0 and system 1, and when one of these two systems becomes unusable, the receiving system switches from the unusable receiving system. This is a device that does not hinder the data reception by switching to the use of the selected data, the 0-system buffer 501 and the 1-system buffer 502.
, A system 0 switching cell detection unit 503, a system 1 switching cell detection unit 504, a switching control unit 505, and a selection unit 506.

[0005] More specifically, the two receiving systems described above include a 0-system receiving system including a 0-system buffer 501, a 0-system switching cell detecting unit 503, and a selecting unit 506. Comprises a 1-system buffer 502, a 1-system switching cell detection unit 504, and a selection unit 506. The 0-system buffer 501 and the 1-system buffer 502 are input to ATM cells in which data transmitted from an external transmitter and arriving after being branched into two different paths is stored, ie, input to the 0-system and 1-system reception systems, respectively. This is a rewritable memory for temporarily storing these ATM cells.

The 0-system switching cell detectors 503 and 1
The system switching cell detection unit 504 includes the 0 system buffer 50
Data is read from the 1 and 1 system buffers 502 in ATM cell units, and it is determined whether or not the ATM cell is a switching cell indicating an instruction for instantaneous interruption switching.
The switching cell is output as it is, and in the case of the switching cell, the fact that the switching cell is detected is notified to the switching control unit 505, and the switching cell is discarded.

[0007] The switching cell is generated by an external transmitting device that transmits data to the receiving system switching device 500, and is inserted into the position of the ATM cell where the above-mentioned non-instantaneous switching is performed. The selection unit 506 is connected to one of the 0-system switching cell detection unit 503 and the 1-system switching cell detection unit 504 according to an instruction from the switching control unit 505, and receives and outputs data from the connection destination switching cell detection unit. .

[0008] The switching control unit 505 is a device for determining which of the 0-system and 1-system receiving systems to use the data received, and includes a 0-system switching cell detecting unit 503 and a 1-system switching system. When the cell detection unit 504 is notified that a switching cell has been detected, a reception system (hereinafter, referred to as “working system”) on the side using data has been used.
That is, in the receiving system to which the selection unit 506 has been connected, reading of the ATM cell after the switching cell by the active switching cell detection unit is stopped and the ATM cell is accumulated in the active buffer.

On the other hand, in a receiving system (hereinafter, referred to as a "standby system") on the side that has not used the data even though the data has been received, the switching control unit 505 waits for the ATM cells after the switching cell. The reading is stopped by the switching cell detection unit of the system, and the reading is accumulated in the standby system buffer. Then, the switching control unit 505 instructs the selection unit 506 to switch the connection from the switching cell detection unit that has been the active system to the switching cell detection unit that has been the standby system so far. The suspension of data reading of the system switching cell detection unit 503 and the system switching cell detection unit 504 is released,
Data reading from the 0-system buffer 501 and the 1-system buffer 502 is started.

FIG. 6 shows an AT storing data in a conventional receiving system switching apparatus 500 configured as described above.
6 is a timing chart showing input / output of M cells, and also shows data transmission timing in a transmission device that transmits the ATM cells to the reception system switching device 500. Here, the alphabet in the figure indicates an ATM cell, and the same alphabet indicates the same content.

The numbers to the right of the alphabet represent the receiving system switching device 500 that has received this ATM cell.
The number of the receiving system in the box indicates that the number is not written to the right of the alphabet. First, in the transmitting device, when the switching cell “X” is inserted between the ATM cells “E” and “F” and transmitted, the received signal is received by the 0-system receiving system and the 1-system receiving system of the receiving system switching device 500. You.

At this time, the ATM cells received by the 0-system reception system and the 1-system reception system arrive via different transmission paths. Is done. Here, the first working system is a system 0 receiving system, and the standby system is a system 1 receiving system. The ATM cells "A0, B0,... E0" which are the system 0 receiving data are shown. Reaches the selection unit 506.

Then, in the current system 0, the AT
After the M cell "E0", the switching cell "X
"0" is detected, and the subsequent ATM cells are buffered, and the output of the ATM cells to the selection unit 506 is stopped. Further, in the system 1 which is the standby system, the switching cell “X1” is detected later than the system 0, buffering the subsequent ATM cells, and stopping the output of the ATM cells to the selection unit 506.

[0014] Then, the selection unit 506 switches the receiving system to be connected, and the 0-system switching cell detection units 503 and 1
The system switching cell detection unit 504 includes the 0 system buffer 50
Data reading from the first and first system buffers 502 and output to the selection unit 506 are started, and the ATM cell “F” of the first reception system newly connected to the selection unit 506 is received.
1, G1, H1,... "Reach the selection unit 506.

In the receiving system that receives the switching cell with a delay, when the switching cell is detected, the non-instantaneous interruption switching is immediately performed so that the buffering of the ATM cell after the switching cell may not be performed. Conceivable. As described above, the conventional receiving system switching device 500 uses the switching cell to realize switching of the receiving system during reception without causing duplication or loss of data output from the selection unit 506.

As an example of the above-mentioned receiving system switching device, there is a "non-instantaneous interruption receiving system switching device" disclosed in Japanese Patent Application Laid-Open No. 5-227196.

[0017]

However, in the conventional receiving system switching apparatus, as described above, first, for each of the ATM cells received in the two receiving systems, the ATM cell is checked, and the switching cell is detected. At the time of instantaneous interruption switching, both systems of ATM cells must be buffered. Therefore, as a device configuration, a switching cell detection unit and a buffer are indispensable configurations.

Accordingly, there is a problem that the cost of the receiving system switching device and the transmitting device increases by incorporating these functional units. Therefore, the present invention has been made in view of the above problems, and in a receiving system switching device, a receiving system switching device, a receiving system disconnection method, and a receiving system switching device capable of performing instantaneous interruption switching with a simpler configuration. The purpose is to provide a system.

[0019]

In order to achieve the above object, a receiving system switching device according to the present invention comprises: first receiving means for receiving data sequentially transmitted from an external device; and said first receiving means. And a second receiving unit for receiving the data from the external device via a route different from the route received by the external device, and selectively connected to one of the first receiving unit and the second receiving unit, and receiving data from the connection destination. Selection output means for outputting the data, and detection means for detecting the necessity of switching the connection of the selection means. When the detection is performed, the external device is instructed to stop data transmission, and the transmission is already performed. After all the data no longer exists on the path to the selection output means, the selection output means switches the receiving means connected to the other reception means to execute the output, and causes the external device to execute the output. Characterized in that it comprises a switching means for performing an instruction to start data transmission to.

Further, a receiving system disconnection method according to the present invention is a receiving system switching method for switching between the first receiving unit and the second receiving unit in an apparatus provided with a first receiving unit and a second receiving unit, the method comprising: A first receiving step of receiving data transmitted more sequentially by using a first receiving unit; and transmitting the data from the external device through a path different from a transmission path of the data received in the first receiving step. (2) a second receiving step of receiving using a receiving means, a detecting step of detecting the necessity of the switching, and selectively connecting to one of the first receiving means and the second receiving means; Receiving and outputting the data, and when the detection is performed, instructs the external device to stop the transmission and sends all the data already transmitted to the selection output means. In after that no longer exist on the path,
A switching step of causing the selection output means to switch the receiving means at the connection destination to another receiving means to execute the output, and instructing the external device to start transmission.

Further, a receiving system switching system according to the present invention is a receiving system switching system comprising the above receiving system switching device and a transmitting device for transmitting data to the receiving system switching device as a packet. , Transmitting data to the first receiving means and the second receiving means in parallel,
When a stop instruction of data transmission is issued from the reception system switching device, the transmission is stopped between packets, and when a start instruction of data transmission is issued from the reception system switching device, the transmission of the packet transmitted immediately before the stop is performed. Transmission is started from the next packet.

[0022]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram of a receiving system switching device 90 according to an embodiment of the present invention. FIG. 1 shows a transmitting device 2 that stores data in an ATM cell and transmits the data to a receiving system switching device 90.
00 is also displayed.

The receiving system switching device 90 includes a system 0 and a system 1
System has two reception systems, and even if one of the reception systems becomes unusable, switching to the use of data received from the other reception system that does not have a problem has hindered data reception. This is a device for preventing the transmission, and includes a 0-system receiving unit 91, a 1-system receiving unit 92, a selecting unit 101, a 0-system switching control unit 102, and a 1-system switching control unit 103.

Here, of the two receiving systems, the 0-system receiving system is the 0-system receiving unit 91, and the 1-system receiving system is the 1-system receiving unit 92. 0-system receiving unit 91
Receives an ATM cell storing data to be transmitted via an external transmission apparatus 200, which is one of transmission paths branched and connected to two different paths, that is, data transmitted via a 0-system transmission path, Output to the 0-system switching control unit 102 and the selection unit 101.

On the other hand, the 1-system receiving section 92 receives an ATM cell storing data transmitted from the external transmitting apparatus 200 via a transmission path different from the 0-system transmission path, that is, the 1-system transmission path. , 1-system switching control section 103 and selection section 101
Output to The selection unit 101 is a switch that selectively connects to the 0-system reception unit 91 and the 1-system reception unit 92.
In accordance with instructions from the 0-system switching control unit 102 and the 1-system switching control unit 103, it is connected to either the 0-system transmission line or the 1-system transmission line, and receives and outputs data from the connection destination.

The 0-system switching control unit 102 includes a ROM, a CPU, a timer, and the like in which a program for executing a process to be described later is stored, receives data coming from the 0-system receiving unit 91, and receives the data. To determine whether or not there is a problem with the receiving system, receive a switching instruction from an external switching instruction device, and
Control for switching the connection from one transmission path to the other transmission path, that is, for performing instantaneous interruption switching (hereinafter referred to as “switching control”), so that duplication or loss of data being received in 1 does not occur. Is implemented.)

On the other hand, the 1-system switching control section 103 stores a ROM, a C
It comprises a PU and a timer, etc., receives data arriving from the 1-system receiving section 92, recognizes whether or not data is arriving, and grasps whether or not the receiving system is obstructed. 102, a flag indicating whether a switching instruction has been issued is received, and the 0-system switching control unit 102
The switching control is performed in the same manner as described above.

FIG. 2 is a sequence diagram showing the contents of the start control and the switching control. Here, before describing the switching control, the state where the reception system switching device 90 is activated will be described first. When the power of the reception system switching device 90 is turned on, the system 0 switching control unit 102 sets the value of the CHG flag indicating whether or not a switching instruction has been issued to “0”, that is, the system 1 switching system controller determines that the switching instruction has not been issued. The flag is output to the switching control unit 103 (step S10), and the flag “OPE =
0 ”, that is, the own system is determined to be the active system and output to the 1-system switching control unit 103 and the selecting unit 101 (Step S
12).

On the other hand, the 1-system switching control unit 103, which has received the flag "OPE = 0" from the 0-system switching control unit 102, is not the destination of data used by its own system, that is, is the standby system. Recognizing that, the system outputs the flag “OPE = 1” indicating that the own system is the standby system to the 0-system switching control unit 102 and the selecting unit 101 (step S1).
3).

The selection unit 101 receives the OPE flags from the two switching control units of the 0-system switching control unit 102 and the 1-system switching control unit 103. It connects to the receiving unit, that is, the 0-system receiving unit 91. Subsequently, when the 0-system switching control unit 102, which is the active system, receives the flag “OPE = 1” from the 1-system switching control unit 103, the 0-system switching control unit 102 issues an output start instruction to the external transmitting device 200 to start outputting data. (Step S)
14).

According to the output start instruction, external transmitting apparatus 200 starts data transmission. in this way,
When the transmission is started, according to the maintenance of the receiving system or the occurrence of a failure, a receiving system having no problem is set as the active system until an external switching instruction device instructing the switching of the receiving system issues a switching instruction. Only the data received by the active system 0 reception system is received from the selection unit 101 and output.

When the 0-system switching control unit 102 receives the switching instruction from the above-mentioned switching instructing device (step S15), the flag “CHG = 1” indicating to the 1-system switching control unit 103 that the switching instruction has been issued. Is output to the 1-system switching control unit 103 (step S16), and a signal indicating an output stop instruction to stop data output is output to the external transmitting device 200, and the timer is started (step S17).

When the time set in the timer elapses, the 0-system switching control unit 102 sets “0” and “1”.
Among the values of “OP” currently associated with the own system.
A value different from the value of "E", that is, "OPE = 1" is output to the 1-system switching control unit 103 and the selection unit 101 (step S18). That is, the association of the active system and the standby system with the own system is changed, and the other functional units are notified.

On the other hand, the 1-system switching control unit 103, which has received the flag “OPE = 1” from the 0-system switching control unit 102, recognizes that its own system is the working system and sets the value of the OPE flag to “0”. Is output to the 0-system switching control unit 102 and the selection unit 101 (step S19). Then, the selection unit 10
1 is a system 0 switching control unit 102 and a system 1 switching control unit 103
The OPE flag is received from the two switching control units, and is connected to the receiving unit on the receiving system side where this value is 0, that is, the 1-system receiving unit 92.

Subsequently, when the 1-system switching control unit 102 outputs the flag “OPE = 1” from the 0-system switching control unit 102, the 1-system switching control unit 102 indicates an output start instruction to the external transmitting apparatus 200 to start data output. Output a signal (step S2
0). Note that the setting time of the above-described timer is usually from the time when an instruction to stop data output is issued to the external transmitting apparatus 200 to the time when the ATM cell immediately before the data output is stopped by this instruction is selected by the selection unit 101. This is a value obtained by estimating the maximum value of the time required to reach the two receiving systems. The 0-system switching control unit 102 and the 1-system switching control unit 103 determine that all of the already transmitted Arrives at the route to the selection unit 101,
It is recognized that data no longer exists on this route.

In addition, since the external transmitting apparatus 200 performs transmission in ATM cell units, the transmission is started and stopped at the boundaries between ATM cells. A description will be given of data input / output realized by the reception system switching device 90 by the above switching control. FIG. 3 shows a transmitting device 200,
9 is a timing chart showing the flow of ATM cells storing data in the selection unit 101 and the 0-system and 1-system reception systems.

Here, alphabets in the figure indicate ATM cells, and the same alphabet indicates the same content. Also, the number written to the right of the alphabet indicates the receiving system switching device 50 that has received this ATM cell.
The number of the receiving system within 0 is shown, and if not numbered to the right of the alphabet, it indicates that the data is data in the transmitting device.

The ATM cells "A, B... E" transmitted by the transmitting apparatus 200 arrive at the 0-system receiving system and the 1-system receiving system with a delay, and are received by the active 0-system receiving system. Only “A0, B0... E0” reaches the selector 101 and is output. At this time, since the ATM cells received by the 0-system reception system and the 1-system reception system arrive via different transmission paths, the ATM cells of the same content are transmitted.
Focusing on the cells, they are received at different times.

Then, in the transmitting device 200, the ATM
Immediately after transmitting the cell "E", an output stop instruction is received, and the transmission is immediately stopped because there is no ATM cell being transmitted. In addition,
During this time, transmitting apparatus 200 transmits A following ATM cell “E”.
The TM cell “F, G,...” Is buffered in its own device. The 0-system switching control unit 102 counts up by an internal timer, and when the set time has elapsed, instructs the selection unit 101 to switch the connection by using the OPE flag.

It should be noted that the set time is such that the ATM cell “E” transmitted from the transmitting device 200 is
It is set so that the set time elapses after the ATM cells “E0” and “E1” reach the 0-system and 1-system reception systems of 0. The 1-system switching control unit 102 instructs the external transmission device 200 to start outputting data, and in accordance with this instruction, the transmission device 200 outputs ATM cells “F, G,...”.

The ATM cells “F, G,...” Reach two receiving systems, but only the ATM cells “F1, G1,. Reaches the selection unit 101 and is output. The details of the switching control process for realizing such a data flow will be described below. FIG. 4 is a flowchart illustrating the details of the switching control process performed by the 0-system switching control unit 102 and the 1-system switching control unit 103.

This flowchart is based on the 0 system switching control unit 1
02 and 1 system switching control unit 103,
Here, the system 0 switching control unit 102 will be described as an example.
The 0-system switching control unit 102 determines whether the own system is the 0-system receiving system (step S100). If the own system is the 0-system receiving system, the 0-system switching control unit 102 resets its own CHG flag to “0”. "CHG = 0" is output to another switching control unit (step S101).

The other switching control unit that has received “CHG = 0” sets a value different from the value of the received CHG flag among “0” and “1”, that is, “1” indicates the value of its own CHG flag. Recognize that it is a value. On the other hand, if the own system is not the system 0 receiving system, the step S101 of outputting “CHG = 0” to another switching control unit is not performed as described above.

The 0-system switching control unit 102 determines whether the own system is the working system, that is, whether the OPE flag is 0 (step S102).
“0” is output to the other switching control unit and the selection unit 101 (step S104), and an instruction to start outputting data is given to the external transmitting device 200 (step S105). On the other hand, if it is not the active system, that is, if it is the standby system,
“OPE = 1” is output to the other switching control unit and selection unit 101 (step S103).

Subsequently, the 0-system switching control unit 102 determines whether or not a switching instruction from an external switching instruction device or “CHG = 1” has been received (step S106).
If the switching instruction or “CHG = 1” has not been received, the state is maintained. On the other hand, when the switching instruction or the reception of “CHG = 1” is performed, the 0-system switching control unit 102 determines whether the own system is the 0-system receiving system (step S107), If it is a system, it outputs "CHG = 1" to another switching control unit (step S108).
No output to such another switching control unit is performed.

Then, the 0-system switching control unit 102 determines whether the own system is the working system (step S109), and if it is the working system, instructs the external transmitting device 200 to stop outputting data. To start the timer (step S1
10) After the timer has exceeded the threshold value, "OPE =
"1" is output to the other switching control unit and selection unit 101 (steps S111 to S112), and the process proceeds to step S106 to determine whether a switching instruction from an external switching instruction device or reception of "CHG = 1" has been performed. Return.

On the other hand, in step S109 for judging whether the own system is the working system, if the own system is not the working system, the 0-system switching control unit 102 sets “O”
After receiving "PE = 1", "OPE = 0" is output to the other switching control unit and the selection unit 101 (step S1).
13 to 114), an instruction to start outputting data is issued to the external transmitting apparatus 200 (step S115), and it is determined whether a switching instruction from the external switching instruction apparatus or “CHG = 1” has been received. It returns to step S106.

As described above, according to the present embodiment, neither a buffer nor a detector for examining the contents of an ATM cell is required.
With a simple device configuration, instantaneous interruption switching can be realized. In this embodiment, transmitting apparatus 200 stores data in an ATM cell and transmits the data.
The data is not limited to the TM cell and may be any data stored in the packet.

In this case, the start and stop of data transmission are performed at the boundaries between packets. Further, in the present embodiment, the 0-system receiving unit 91 and the 1-system receiving unit 92 do not include a buffer for temporarily storing data. ,
103, instead of judging the elapse of the time set in the timer, judges that the respective buffers of the 0-system receiving unit 91 and the 1-system receiving unit 92 both underflow, and these buffers both underflow. In this case, each of the switching control units 102 and 103 switches another value among the values of “0” and “1” that is different from the value of “OPE” currently associated with the own system. The information may be output to the control unit and the selection unit 101.

Although the 0-system switching control unit 102 receives the switching instruction from the switching instruction device, the switching instruction may be received from the external transmitting device 200 or may be received from the selecting unit 101. . In the present embodiment,
Although the active and standby receivers have received the same data in parallel, although there is a difference in the reception timing, only the active receiver may receive the data.

In this case, the switching control unit of the standby system does not receive data from the receiving unit, and therefore does not recognize whether or not data has arrived and does not know whether or not the reception system has been affected. The 0-system switching control unit 102 and the 1-system switching control unit 103 include a ROM, a CP,
U and a timer, etc.
(Field Programmable Gate
Needless to say, the same effect can be obtained even if the expression is replaced with Array).

In the present embodiment, the 0-system switching control unit 102 and the 1-system switching control unit 103
However, the configuration may be included in the external transmission device 200. In this case, the output of the signal indicating the OPE flag to the selecting unit 101 is performed by the external transmitting device 20.
0 is output.

Further, in the present embodiment, the 0-system switching control unit 102 and the 1-system switching control unit 103 are independent function units, respectively, but they may be integrated into one function unit. In this case, at least one arithmetic unit such as a CPU is sufficient, and the OPE flag output from the 0-system switching control unit 102 and the 1-system switching control unit 103 to the selection unit 101 until then is connected. The selection unit 101 that has been replaced with one flag indicating the receiving unit to be switched receives the flag, and switches the connection to the 0-system receiving unit 91 and the 1-system receiving unit 92 according to this flag.

[0054]

As is apparent from the above description, the receiving system switching apparatus according to the present invention comprises a first receiving means for receiving data sequentially transmitted from an external device, and a path for receiving data transmitted by the first receiving means. A second receiving means for receiving the data from the external device through a different path from the external device, and a selective connection for selectively connecting to one of the first receiving means and the second receiving means to receive and output the data from the connection destination Output means, detecting means for detecting the necessity of switching the connection of the selecting means, and when the detection is performed, instructs the external device to stop data transmission, all the data already transmitted is After the data is no longer present on the path to the selection output means, the selection output means switches the receiving means connected to the other reception means to perform the output, and causes the external device to perform data output. Switching means for instructing the start of data transmission, and a method of switching the receiving system according to the present invention, wherein the apparatus comprising the first receiving means and the second receiving means comprises a first receiving means and a second receiving means. A receiving system switching method for switching a receiving unit, comprising: a first receiving step of receiving data sequentially transmitted from an external device using a first receiving unit; and a transmission path of the data received by the first receiving step. A second receiving step of receiving the data from the external device using a second receiving unit using a different path from the external device, a detecting step of detecting the necessity of the switching, and a first receiving unit and a second receiving unit. Selective connection with either one, a selection output step of receiving and outputting data from the connection destination, and when the detection is performed, instructs the external device to stop transmission, After all the data transmitted to the selection output unit is no longer present on the path, the selection output unit switches the connection destination reception unit to another reception unit to execute the output, A switching step of instructing the external device to start transmission.

Thus, if the external device stops and starts data transmission in accordance with the stop instruction and the start instruction at data transmission unit breaks, data can be received without duplication or loss. System switching is performed. Further, the receiving system switching system according to the present invention is a receiving system switching system including the receiving system switching device and a transmitting device that transmits data to the receiving system switching device as a packet, wherein the transmitting device transmits data. The first
When the data is transmitted in parallel to the receiving means and the second receiving means, and the receiving system switching device issues an instruction to stop data transmission, the transmission is stopped between packets, and the receiving system switching device issues an instruction to start data transmission. When transmission is performed, transmission is started from a packet next to the packet transmitted immediately before the stop.

As a result, switching of the receiving system is performed without duplication or loss of packets. Further, the data received by the first receiving means and the second receiving means is stored in a packet, and the switching means is configured to output the data from the external device from the time when the instruction to stop the data transmission is issued. The fact that the estimated time required for the output packet to be received by the selection output means has elapsed may be recognized as the absence of all the data on the path.

Thus, even if it takes time for the packet transmitted immediately before the stop of the data transmission of the external device to reach the reception system switching device, the reception system is switched without duplication or loss of the packet. Further, the first receiving means has a first memory for temporarily storing received data, and the second receiving means has a second memory for temporarily storing received data, and the switching means Is the first
The fact that both the memory and the second memory have underflowed may be recognized on the path as the absence of all the data.

Thus, even if it takes time for the packet transmitted immediately before the stop of the data transmission of the external device to reach the receiving system switching device, the receiving system is switched without any duplication or loss of the packet. .

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a reception system switching device according to an embodiment of the present invention.

FIG. 2 is a sequence diagram showing the contents of startup control and switching control.

FIG. 3 is a timing chart showing a flow of ATM cells storing data in a transmission device, a selection unit, and a 0-system and 1-system reception system.

FIG. 4 is a flowchart illustrating details of switching control processing in a 0-system switching control unit 102 and a 1-system switching control unit.

FIG. 5 is a block diagram of a reception system switching device in a conventional ATM.

FIG. 6 is a timing chart showing input and output of ATM cells storing data in a conventional reception system switching device.

[Explanation of symbols]

 Reference Signs List 90 receiving system switching device 91 0 system receiving unit 92 1 system receiving unit 101 selecting unit 102 0 system switching control unit 103 1 system switching control unit 200 transmitting device

Claims (5)

[Claims] A first receiving unit that receives data sequentially transmitted from an external device; and a second receiving unit that receives the data from the external device via a path different from a path received by the first receiving unit. Selection output means for selectively connecting to one of the first reception means and the second reception means, receiving and outputting data from a connection destination, and detection means for detecting the necessity of switching the connection of the selection means When the detection is performed, the external device instructs the external device to stop data transmission, and after all the already transmitted data no longer exists on the path to the selection output unit, the selection is performed. Switching means for causing the output means to switch the receiving means connected to the other receiving means to perform the output, and instructing the external device to start data transmission. Shin system switching device. 2. The data received by the first receiving unit and the second receiving unit is stored in a packet, and the switching unit performs the data transmission from the time when the instruction to stop the data transmission is issued. Recognizing, on the path, that all of the data does not exist, that a time estimating a time required for a packet output from an external device to be received by the selection output means has elapsed. The receiving system switching device according to claim 1. 3. The first receiving means has a first memory for temporarily storing received data, and the second receiving means has a second memory for temporarily storing received data, 2. The switching unit according to claim 1, wherein the switching unit recognizes that both the first memory and the second memory have underflowed on the path as all the data do not exist. 3. Reception system switching device. 4. A receiving system switching method for switching between a first receiving unit and a second receiving unit in an apparatus including a first receiving unit and a second receiving unit, wherein data sequentially transmitted from an external device is transmitted to the first receiving unit. A first receiving step of receiving using the receiving unit, and a second receiving of the data from the external device using a second receiving unit via a path different from a transmission path of the data received in the first receiving step. A receiving step, a detecting step of detecting the necessity of the switching, a selective output step of selectively connecting to one of the first receiving means and the second receiving means, receiving and outputting data from a connection destination, When the detection is performed, the external device is instructed to stop transmission, and after all the already transmitted data no longer exists on the path to the selection output unit, A switching step of causing the selection output means to switch the receiving means connected to another receiving means to perform the output, and instructing the external device to start transmission. . 5. A receiving system switching system comprising: the receiving system switching device according to claim 1; and a transmitting device that transmits data to the receiving system switching device as a packet, wherein the transmitting device transmits data to the first system. When the transmission is performed in parallel to the receiving means and the second receiving means, and the receiving system switching device instructs to stop data transmission, the transmission is stopped between packets, and the receiving system switching device instructs to start data transmission. Wherein the transmission is started from a packet next to the packet transmitted immediately before the stop.