JPH09294125A - Cell exchange system and cell data warrant system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain system changeover of a cell switch without causing missing cells. SOLUTION: A number provision section 111 provides a sequential number to a received asynchronous transfer mode(ATM) cell to generate a unique ATM cell, the generated unique ATM cell is sent to an ATM cell switch 20, where it is tentatively stored. A sequential number notice section 22 sends a transmitted cell number to a number check section 121 and a system section 10 upon the receipt of the unique ATM cell. The system control section 10 informs the received transmission finish cell number to an ATM switch buffer section 100 of a transmission source. Upon the receipt of the transmission finished cell number, a number storage section 122 updates a storage number of the corresponding ATM cell switch 20. When an active system is switched from the ATM cell switch 20 to a cell switch 30, the number provision section 111 receives a system changeover notice and a cell number from a retransmission control section 112, reads the unique ATM cell corresponding to the sequential number not sent yet and sends it to the ATM cell switch 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell switching system such as an ATM (asynchronous transfer mode) switching system, and more particularly to a cell switching system in which a cell switch is duplicated. The present invention relates to a cell switching system and a cell data guarantee method for guaranteeing cell continuity when a system is switched from an active system to a standby system.

[0002]

2. Description of the Related Art In a broadband digital communication network or the like, an ATM switching system has been attracting attention as a communication switching system for handling a large amount of data at high speed. This AT
The M switching system asynchronously transfers ATM cells formed into cells in a predetermined format to perform data communication.
A cell may be considered as a kind of packet having a predetermined format like a frame in frame relay.

In the ATM switching system, the ATM cell switch is duplicated so that one is used as a working system and the other is used as a standby system, and when a failure occurs in the working system, the system is switched to protect the system. Is done. At the time of system switching, from the active system in operation of the exchange system to the standby system,
That is, the active system in operation is switched to the standby system, and the standby system is switched to the active system.

A conventional example of a data guarantee system at the time of system switching is disclosed in Japanese Patent Laid-Open Nos. 5-56078 and 5-2.
No. 27191.

First, the first method, that is, Japanese Patent Laid-Open No. 5-5
The method disclosed in Japanese Patent No. 6078 will be described. As shown in FIG. 3, the main part of the system according to the first method is a buffer memory 1, a packet assembling unit 2, a transmission processing unit 3, a route changeover switch 4, a received packet sequence number storage unit 5, a retransmission request control unit. 6, a packet disassembly unit 7 and a reception processing unit 8.

The retransmission request control unit 6 stores a transmission sequence number buffer 6-1 for a transmission sequence number, a return sequence number buffer 6-2 for a returned sequence number, the transmission sequence number and a return sequence number. It has a comparison circuit 6-3 for comparison.

When the terminal sends a message, the packet assembling unit 2 adds a sequence number to each packet and sends the message, and each packet and the sequence number are stored in the buffer memory 1.

The sequence number is also stored in the transmission sequence number buffer 6-1 of the retransmission request control unit 6. When the delivery confirmation packet returned from the receiving side is received, the returned sequence number is returned to the return sequence number buffer 6-
Stored in 2. These sequence numbers correspond to the comparison circuit 6
-3, the buffer is cleared or a resend request process for missing data is performed.

At the time of system switching, the resending request control unit 6 performs resending request processing again after waiting for the receipt of the returning sequence number sent back from the receiving unit through the switched route.

When the terminal receives a message, the received packet is separated into a sequence number and a message, the separated sequence number is returned from the packet assembling unit 2 to the transmitting unit, and the received packet sequence number storage unit is also provided. 5, these are accumulated. At the time of route switching, as described above, the accumulated sequence number is transmitted by the switched route.

In the first method shown in FIG. 3, when the packet route is switched, the receiving side terminal retransmits the packet based on the sequence number. This method is
A program for performing resend processing is required for the software on the terminal side, and real-time processing cannot be performed.
Not suitable for transfer of TM cells.

The second method disclosed in Japanese Patent Laid-Open No. 5-227191 will be described. The main part of the ATM switch used in the system according to the second method is
It is configured as shown in FIG. In this case, the ATM switch 9 includes a selector 9-1, buffers 9-2, 9-.
3 and switching flag detectors 9-4 and 9-5 are provided.

The cells from the active system and the standby system are once input to buffers 9-2 and 9-3, which are FIFO (first in, first out) buffers, respectively, and the selector 9 is used.
At -1, one of these outputs is selected and sent to a demultiplexer (not shown). The switching flag detectors 9-4 and 9-5 respectively include the buffer 9-2.
And the switching flag input to 9-3 is detected. The buffers 9-2 and 9-3, and the switching flag detector 9-4,
9-5 are provided symmetrically so that switching in any direction is possible.

At the time of system switching, a switching flag is inserted on the output side of all devices on the input side, and all valid flags thereafter are marked. Due to the difference in the delay time of each route, the switching flag, the unmarked cell, and the marked cell are sequentially given from the active system and the standby system.

In the active buffer 9-2, the marked cells are discarded and only the unmarked cells are input. On the contrary, in the standby buffer 9-3, the unmarked cells are discarded and only the marked cells are input. . Since the selector 9-1 selects the output of the buffer 9-2, the buffer 9-2
The unmarked cells input to the buffer are sequentially ejected, and the marked cells input to the buffer 9-3 are accumulated.

During this time, the switch flag detecting section 9-4 detects the switch cells at the input of the buffer 9-2, and when the switch cells from all the input ports are detected,
As soon as the buffer 9-2 becomes empty, the selector 9-1 is switched to select the output of the spare buffer 9-3. At this time, all the valid cells without marks must have been output from only the active system through the selector 9-1, and all the marked cells are present on the spare system side.

Therefore, when the selector 9-1 is switched, the switching from the active system to the standby system is achieved without causing cell duplication and loss. If the marking of the cell on the input side is stopped at the same time as the switching of the selector 9-1, the unmarked cells are gradually replaced, and the switching operation ends when all the cells are replaced by the unmarked cells.

In the second method shown in FIG. 4, the ATM cell at the time of switching is provided by providing a switching flag in the ATM cell.
Guarantee the cell. According to this method, during regular switching,
It is possible to perform system switching without interruption without loss of ATM cells. However, during emergency switching due to a failure, etc.
There is a risk of missing ATM cells.

[0019]

Among the above-mentioned conventional data guarantee methods in system switching, Japanese Patent Laid-Open No. 5-56078
The method disclosed in the publication, that is, the first method is realized by software processing in the terminal on the receiving side, as described above. Therefore, the first method is not suitable for processing such as ATM cell exchange, which requires high speed, because not only a program for resending processing is required in the receiving side terminal but also resending processing depends on software processing.

Moreover, in the first method, it is necessary for software to unconditionally send back a response even for a packet for which a response is unnecessary. Further, if the system switching is performed during the return of the response, the information may not be correctly transmitted to the transmission source and may be retransmitted, and the same packet may be transmitted in duplicate.

Among the data guarantee methods in the conventional system switching described above, in the method disclosed in Japanese Patent Laid-Open No. 227191/1993, that is, the second method, switching is performed by providing a switching flag in the ATM cell. Guarantee ATM cells at time. Therefore, at the time of regular switching, it is possible to perform system switching without interruption without loss of ATM cells. However, during emergency system switching due to a failure, etc.
It was difficult to carry out system switching without missing TM cells.

The present invention has been made in view of the above-mentioned circumstances, and assigns a sequential number to a cell to make it a unique cell and receives a sequential number that has been completely received, so A cell switching system and a cell that can be automatically retransmitted promptly to enable system switching of a cell switch without missing cells even when a system switching is required due to an emergency such as a failure, and can improve reliability. It is intended to provide a data assurance method.

[0023]

In order to achieve the above object, a first cell switching system according to the present invention is provided with a duplicated cell switch means for performing cell switching and provided for each line, and sequentially from each line. Sequential numbers are once added to the given cells, the cells are once stored, the cells with the sequential numbers are sent to each of the duplicated cell switch means, and based on the reception completion notification from the destination by the sequential numbers. , Discard the accumulated cells and sequential numbers, store the final value for each corresponding line to the sequential number of the cell that has been received by the cell switch means, and complete the reception by the sequential number of the cell that has received The notification is added to the cell that is sent to the source of that cell, and the transmission is completed when the system is switched. A plurality of cell switch buffer means for sending the accumulated cells after the non-sequential number to the cell switch means immediately after the system switching, prior to the cells received from the line, and the dual system of the cell switch means. And system control means for performing system switching control.

The system control means may include means for receiving the sequential number of the transmitted cell from the cell switch means and notifying the switch buffer means of the transmission source. The cell switch buffer means may include means for receiving the sequential number of the transmitted cell from the cell switch means and notifying the switch buffer means of the transmission source.

A second cell switching system according to the present invention comprises a dual cell switch for performing cell switching, a cell switch buffer section provided for each line, and a cell switch buffer section for switching the dual cell switch from the cell switch buffer section. In a cell switching system including an interface for transmitting and receiving cells to and from each, and a system control unit that performs dual system switching control of the cell switch, the cell switch buffer unit assigns a sequential number to the cells. A numbering unit that generates a unique cell having a unique format different from that of the received cell, a retransmission control unit that notifies the numbering unit of the cell to be retransmitted, and a buffer that temporarily holds the transmitted unique cell. Cell transmission section including a section, each of the above based on the sequential number of the transmitted original cell The number holding unit that holds the latest information for each switch switch unit, and the number check unit for causing the buffer unit of the cell transmission unit to discard the unique cell based on the holding number of the number holding unit. With a cell receiving unit including, the cell switch includes means for notifying the cell receiving unit of the cell switch buffer unit of the sequential number of the unique cell already transmitted, the system control unit, Means for performing system control, means for receiving the sequential number of the transmitted unique cell from the cell switch, and notifying the retransmission control unit and the number holding unit of the cell switch buffer unit of the transmission source, , And means for notifying the system switching to all the cell switch buffer units.

In a third cell switching system according to the present invention, a duplicated cell switch for performing cell switching, a cell switch buffer unit provided for each line, and a duplicated cell switch from the cell switch buffer unit are provided. In a cell switching system including an interface for transmitting and receiving cells to and from each, and a system control unit that performs dual system switching control of the cell switch, the cell switch buffer unit assigns a sequential number to the cells. A numbering unit that generates a unique cell having a unique format different from that of the received cell, a retransmission control unit that notifies the numbering unit of the cell to be retransmitted, and a buffer that temporarily holds the transmitted unique cell. Cell transmission section including a section, each of the above based on the sequential number of the transmitted original cell The number holding unit for holding the latest information for each switch switch unit, and the buffer unit of the cell transmission unit discards the unique cell based on the holding number of the number holding unit, and from the cell switch The cell switch has a cell reception unit including the number check unit for recognizing the sequential number of the transmitted unique cell and notifying the retransmission control unit of the cell switch buffer unit, and the cell switch has already transmitted. A means for notifying the cell receiving section of the cell switch buffer section of the sequential number of the unique cell, the system control section, means for performing system control of the cell switch,
A means for notifying a system switching is included in all of the cell switch buffer units.

The number assigning unit assigns a sequential number to the cell to form a unique cell, a unit that reads out the unique cell accumulated in the buffer unit according to a notification from the retransmission control unit, and the cell Including means for writing the unique cell transmitted to the switch in the buffer unit, and means for identifying the cell to which the sequential number should be given, wherein the retransmission control unit is a system of the cell switch from the system control unit. Switching means and means for notifying the numbering unit of the cell to be retransmitted based on the notification of the sequential number of the unique cell already transmitted from the cell switch from the number holding unit, the buffer unit, The unique cell which is temporarily stored by the number assigning unit and responds by the discard cell notification from the number checking unit It may include means for discarding Le.

The numbering unit includes means for generating a unique cell by adding a sequential number notification of the transmitted cell to a receiving cell when there is a receiving cell and to an empty cell when there is no receiving cell. You can leave.

The cell is ATM (asynchronous communication mode)
It may be a cell. A cell data guarantee method according to the present invention provides a duplicated cell switch for performing cell exchange, a cell switch buffer unit provided for each line, and a cell switch buffer unit provided for each duplicated cell switch. In a cell data guarantee method in a cell switching system including an interface for transmitting and receiving data and a system control unit for performing system switching control of the dual system of the cell switch, sequential numbers are given to cells sequentially given from each line. Once stored in the cell switch buffer unit, and sending the cells with sequential numbers to each of the duplicated cell switches, and based on the reception completion notification from the destination by the sequential number, the cell Cells and sequential stored in the switch buffer section Signal, the step of storing the final number for each corresponding line in the cell switch buffer unit of the sequential number of the cell whose reception is completed by the cell switch, and the reception by the sequential number of the cell whose reception is completed. Completion notification is added to the cell transmitted to the transmission source of the cell, and at the time of system switching, the cells accumulated in the cell switch buffer section after the sequential number whose transmission is not completed are stored immediately after system switching. , Sending to the cell switch in preference to cells received from the line,
Having.

The system controller may receive the sequential number of the transmitted cell from the cell switch and notify the switch buffer of the transmission source. The cell switch buffer unit may receive the sequential number of the transmitted cell from the cell switch and notify the source switch buffer unit of the sequential number. The cell may be an ATM (Asynchronous Communication Mode) cell.

In the cell switching system and the cell data guaranteeing method according to the present invention, the cell switch buffer unit provided for each line gives a sequential number to cells sequentially given from each line, accumulates the cells once, and then stores these sequential numbers. The cells marked with are sent to each of the duplicated cell switches, and the accumulated cells and sequential numbers are discarded based on the reception completion notification from the transmission destination by the sequential number, and the reception is completed by the cell switch. The sequential number of each cell is stored as the final value for each corresponding line, and a reception completion notification by the sequential number of the cell whose reception is completed is added to the cell transmitted to the transmission source of that cell, and system control is performed. When switching the system by means, after the sequential number that has not been transmitted The stored electrical cell, immediately after system switching, in preference to cells received from the line and sends it to the cell switch.

Therefore, according to the cell switching system and the cell data guaranteeing method of the present invention, a sequential number is given to a cell to make it a unique cell, and the received sequential number is lost due to system switching. The cells can be automatically retransmitted promptly, so that even when an emergency system switchover such as a failure occurs, the cell switch system switchover can be performed without losing the cell, and the system reliability is also improved.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION A cell switching system according to an embodiment of the present invention will be described below with reference to the drawings. A cell switching system according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the configuration of an ATM cell switching system. The ATM cell switching system shown in FIG. 1 includes a system controller 10, ATM cell switches 20 and 30, and ATM switch buffers 100, ... N.

The ATM cell switch 20 comprises a cell switch section 21 and a sequential number notifying section 22. The sequential number notification unit 22 is provided for each line. The ATM cell switch 30 is also the ATM cell switch 20.
It has the same configuration as

The ATM switch buffer section 100 comprises a transmitting section 110 and a receiving section 120. Transmitter 11
0 has a numbering unit 111, a retransmission control unit 112, and a buffer unit 113. The receiving unit 120 has a number checking unit 121 and a number holding unit 122. The ATM switch buffer units 100 to n are provided for each line and have the same configuration.

The system control unit 10 is coupled to the ATM cell switches 20 and 30 of both systems (that is, the active system and the standby system) that compose the dual system, and the system control is performed from each of the ATM cell switches 20 and 30. The signal 1001 is transmitted, and the transmitted cell number notification 1002 is received. Also,
The system control unit 10 includes each ATM switch buffer unit 100,
, N, and supplies a system switching notice 1003 and a transmitted cell number notice 1004 to each of the ATM switch buffer units 100 ,.

Each ATM switch buffer section 100, ...
n is coupled to both the ATM cell switches 20 and 30 by a transmission cell data line 1005 and a reception cell data line 1006.

Switch unit 21 of ATM cell switch 20
Is common to all lines, and the ATM switch buffer unit 1
Are connected to the respective numbering units 111 ... The sequential number notifying unit 22 ... Of the ATM cell switch 20 receives the ATM cells to which the sequential numbers are added from the switch unit 21, transmits the ATM cells to the number check units 121 of the ATM switch buffer units 100 to n of each line, and The sequential number of the completed ATM cell is notified to the system control unit 10. ATM cell switch 3
0 is configured similarly to the ATM cell switch 20.

As described above, the ATM switch buffer unit 100 includes a cell transmission unit 110 having a numbering unit 111, a retransmission control unit 112 and a buffer unit 113, and a cell reception unit having a number checking unit 121 and a number holding unit 122. The unit 120 is provided. As will be described in detail later, the numbering unit 111 assigns a sequential number to an ATM cell received from a line and has an ATM cell having a unique predetermined format (hereinafter referred to as "unique ATM cell").
Generate Of the ATM switch buffer units 100 to n, the ATM switch buffer units other than the ATM switch buffer unit 100 have the same configuration.

The above-mentioned functions of the respective parts will be described more specifically. ATM as an ATM switch buffer unit
The switch buffer unit 100 is used as an ATM cell switch, and the ATM cell switch 20 is used as an example.
It is assumed that the M cell switch 20 is the active system.

The system control unit 10 uses the ATM cell switch 20.
Has a function of receiving the transmitted cell number notification 1002 from the sequential number notification unit 22 ,. That is, the system control unit 10 uses the ATM switch buffer unit 10
Receives the cell-transmitting sequential numbers assigned to the unique ATM cells transmitted to 0, ..., N.
Also, the system control unit 10 uses the ATM switch buffer unit 10 corresponding to the received sequential number for cell transmission.
It has a function of notifying 0, ..., N by the transmitted cell number notification 1004. Furthermore, the system controller 10
Controls the ATM cell switches 20 and 30. That is, the system control unit 10 performs a system control of the ATM cell switches 20 and 30 by the system control signal 1001 and has a function of notifying the system switching to the respective ATM switch buffer units 100 to n by the system switching notification 1003. Have

Switch unit 21 of ATM cell switch 20
Receives the ATM cells to which the sequential numbers are given from the ATM switch buffer units 100 to n, and sends the ATM cells to the ATM switch buffer units 100 to n corresponding to the required lines.
ATM cells are exchanged by transmitting ATM cells via the sequential number notifying unit 22. ATM cell switch 20
The sequential number notifying unit 22 corresponds to the ATM switch buffer unit 100. The sequential number notifying unit 22 ... Corresponds to the corresponding ATM switch buffer units 100 to n.
When the transmission of the original ATM cell is completed,
The transmitted cell number notification 1002 notifies the system control unit 10.

The number assigning unit 111 has a function of assigning a sequential number to the ATM cells input from the receiving line 2000 and converting the ATM cells into a unique ATM cell of a predetermined format. However, the numbering unit 111 uses the input A
The type of TM cell is discriminated, and a sequential number is not given to a fixed rate cell (specifically, for example, the sequential number is always "0"). The numbering unit 111 also has a function of accumulating the unique ATM cell transmitted to the ATM cell switch 20 also in the buffer unit 113. However, the numbering unit 111 does not store fixed rate cells in the buffer unit 113. Further, the number assigning unit 111 receives the retransmission notification from the retransmission control unit 112, reads out the unique ATM cell to be retransmitted from the buffer unit 113, and from the unique ATM cell and the buffer unit 113 to which a new sequential number is assigned. The original ATM cell read out is transmitted to the cell data line 1005 for transmission.
It has a function of transmitting to the ATM cell switch 20 via the.

The retransmission control unit 112 notifies the numbering unit 111 of the system switching information notified as the system switching notification 1003 from the system control unit 10 and the transmitted sequential number read as the return number notification from the number holding unit 122. Have the function to

The buffer unit 113 temporarily stores the unique ATM cells transmitted from the number assigning unit 111 to the ATM cell switch 20, outputs the unique ATM cells according to an instruction from the number assigning unit 111, and also outputs the number checking unit 1
21 has a function of discarding the unique ATM cell corresponding to the discard cell notification by the discard cell notification from 21.

The number check unit 121 includes a number holding unit 12
2 is referred to for each ATM switch buffer unit 100 to n, and the buffer unit 113
It has a function of notifying the discard cell to the cell, and removing the sequential number from the unique ATM cell received via the receiving cell data line 1006, and sending out as a standard format ATM cell via the transmission line 2001.

The number holding unit 122 receives from the system control unit 10
It has a function of holding the latest information of each of the ATM switch buffer units 100 to n of the sequential number received as the transmitted cell number notification 1004 and notifying it to the number check unit 121.

Next, the operation of the ATM cell switching system thus configured will be described by taking the case where the ATM cell switch 20 is the active system as an example. Naturally AT
The same operation is performed when the M cell switch 30 is the active system. Also, the ATM switch buffer unit 100 will be described as an example.

When an ATM cell is received from the receiving line 2000, the numbering unit 111 gives a sequential number for each destination line to the ATM cell to generate a unique ATM cell. Then, the numbering unit 111 uses the transmission cell data line 1
This unique ATM cell is transmitted to the ATM cell switch 20 via 005, and the buffer section 113 temporarily stores this unique ATM cell. The numbering unit 11
1 indicates that the ATM cell received from the receiving line 2000 is a fixed rate cell such as a so-called CBR cell,
Neither the sequential number is assigned nor the buffer 113 is temporarily stored.

In the ATM cell switch 20, the switch unit 21 performs the exchange processing of the unique ATM cell received via the transmission cell data line 1005. The switch unit 21 sends the received unique ATM cell to the sequential number notification unit (22 ...) Of the corresponding line.

For example, the ATM switch buffer unit 100
The case where there is a transmission to is specifically described.
Upon receiving the unique ATM cell from the switch unit 21, the sequential number notifying unit 22 refers to the sequential number in the unique ATM cell and transmits it to the number check unit 121 of the ATM switch buffer unit 100 via the receiving cell data line 1006. . ATM switch buffer unit 100
Upon completion of the transmission to, the system controller 10 is notified of the sequential number of the transmitted cell as a transmitted cell number notification 1002.

Upon receiving the transmitted cell number from each of the sequential number notifying units 22 ..., The system control unit 10 notifies the transmitted ATM cell buffer unit (100, ..., N) of the transmitted cell number. To do. That is,
Assuming that the ATM switch buffer section 100 is the transmission source, the system control section 10 uses the transmitted cell number as the transmitted cell number notification 1004.
Notify 0.

The number holding unit 122 is controlled by the system control unit 10.
When the transmitted cell number according to the transmitted cell number notification 1004 is received, the corresponding ATM switch buffer unit (1
(00) holding number is replaced with the transmitted cell number, and the transmitted cell number is checked by the number check unit 12
Notify 1.

The number checking unit 121 includes a number holding unit 12
In order to discard the unique ATM cell having the sequential number corresponding to the transmitted cell number notified from 2,
The buffer unit 113 is notified of the discarded cells of the cells having the sequential numbers corresponding to the transmitted cell numbers. The buffer unit 113 temporarily stores A according to the discard cell notification given from the number check unit 121.
Discard the corresponding TM cell. In this way,
In the buffer unit 113, only unique ATM cells that have always been transmitted and have not been received at the destination will be stored.

At this point, some failure or the like occurs, and the active system is switched from the ATM cell switch 20 to the ATM cell switch 3
When it is necessary to switch to 0, it operates as follows.

The system control unit 10 controls the ATM cell switches 20 and 30 via the system control signal 1001 to switch the system from the active system to the standby system, from the standby system to the active system, and to switch all the ATM switches. Buffer unit 100-n
A system switch notification 1003 is sent to the system.

Taking the ATM switch buffer unit 100 as an example, the retransmission control unit 112 uses the system switching notification 1003, that is, the received system switching notification to send the ATM cell switch 2
Recognizing that the system of 0 and 30 has been switched, the sequential number of the latest transmitted (destination received) cell, that is, the cell number is read from the number holding unit 122,
The numbering unit 111 is notified.

When the number assigning unit 111 receives the system switching notice and the cell number from the retransmission controlling unit 112, the number assigning unit 111 compares the cell number with the sequential number for each destination ATM switch buffer unit held internally and receives the same. Retransmission control is not performed for the ATM switch buffer unit (100 to n) that matches the cell number. Only when the cell number is smaller than the sequential number of each destination ATM switch buffer section held internally, the numbering section 111
The accumulated unique ATM cell corresponding to the untransmitted sequential number is read from the buffer unit 113 and transmitted to the new active ATM cell switch 30 via the transmission cell data line 1005.

This retransmission processing is performed by the receiving line 20 after switching the system.
The priority is given to the ATM cell input via 00. This guarantees the order of the transfer cells. However, when a fixed rate cell is input, the ATM cell is transmitted to the ATM cell switch 30 prior to the retransmission processing. This is to suppress the delay and delay fluctuation of the fixed rate cell.

In this way, the ATM cells are given sequential numbers to form unique ATM cells, and by receiving the sequential numbers that have been completely received, the ATM cells that have been lost due to system switching are promptly automatically retransmitted. Therefore, even when the system is switched to an emergency such as a failure, the ATM
The ATM cell switch system can be switched without losing cells.

A cell switching system according to a second embodiment of the present invention will be described with reference to FIG. Figure 2 is ATM
1 shows the configuration of a cell switching system. AT shown in FIG.
The M cell switching system includes a system control unit 10A, ATM cell switches 20A and 30A, and ATM switch buffer units 100A, ...

The ATM cell switch 20A has a cell switch section 21 and a sequential number notifying section 22A. The sequential number notification unit 22A is provided for each line. The ATM cell switch 30A also has the same configuration as the ATM cell switch 20A.

The ATM switch buffer section 100A includes a transmission section 110A and a reception section 120A. The transmission unit 110A includes a numbering unit 111 and a retransmission control unit 112A.
And a buffer unit 113A. Receiver 120A
Is a number checking unit 121A and a number holding unit 122A.
Having. ATM switch buffer section 100A to nA
Are provided for each line and have the same configuration.

In the system shown in FIG. 2, in the ATM cell switching system shown in FIG. 1, the sequential numbers of the transmitted unique ATM cells are notified via the system control unit 10, whereas the transmitted unique ATM cells are transmitted. Notification of the sequential number is performed using the original ATM cell itself. The basic configuration is almost the same as the case of FIG. 1, but the receiving unit 120A of the ATM switch buffer 100A has a unique AT that has transmitted the sequential numbers of the transmitted unique ATM cells.
Since the sequential number of the M cell exists in the unique ATM cell, a function is added in which the number check unit 121A extracts this and notifies the number holding unit 122A.

Further, the sequential number notifying section 22A ...
A function is added to exchange information between each other and give a transmitted cell number to a unique ATM cell to be transmitted to the corresponding ATM switch buffer units 100A, ..., nA. In addition, even when there is no unique ATM cell to be transmitted to the corresponding ATM switch buffer unit 100, ..., N, the transmitted cell number is transmitted as an empty cell, and the latest information is constantly updated. F will notify you.

Therefore, in the system of FIG. 1, the sequential number notifying unit 22 ... to the system control unit 10 and the system control unit 10 to the ATM switch buffer units 100 to 100.
The transmitted cell number notification to the retransmission control unit 112 of n is unnecessary in the ATM cell switching system of FIG.

The operation of the ATM cell switching system of FIG. 2 configured as described above is basically the same as that of the case of FIG. 1, and therefore only the differences will be mainly described. In this system, while the system of FIG. 1 notifies the sequential number of the transmitted unique ATM cell, that is, the transmitted cell number, via the system control unit 10, this notification is performed using the proprietary ATM cell itself. . That is, the sequential number of the transmitted unique ATM cell is the unique AT.
Since it exists in the M cell, this is checked by the number check unit 121.
A is taken out and notified to the number holding unit 122A. Further, the sequential number notifying unit 22A ... Passes information between them, and assigns the transmitted cell number to the unique ATM cell to be transmitted to the corresponding ATM switch buffer units 100A to nA. At this time, the corresponding ATM
If there is no unique ATM cell to be transmitted to the switch buffer units 100A to 100A, the transmitted cell number is added to the empty cell having no communication data and the cell is transmitted. In this way, the latest information is always the ATM switch buffer unit 1
00A to nA are notified.

In the above-mentioned embodiment, A
Although the ATM cell switching system for handling TM cells has been described, the present invention is not limited to ATM cells and transmits transmission data in the form of data cells, or data packet or data frame formats substantially similar thereto. The system can be applied to various exchange systems in the same manner as described above.

[0069]

As described above, in the cell switching system and the data cell guarantee method according to the present invention,
By the cell switch buffer unit provided for each line, the cells sequentially given from each line are sequentially stored with sequential numbers, and the cells with the sequential numbers are sent to each of the duplicated cell switches, and Based on the reception completion notification by the sequential number from the transmission destination, discard the accumulated cells and sequential numbers, save the final value for each corresponding line to the sequential numbers of the cells that have been received by the cell switch, and The reception completion notification by the sequential number of the cell for which the reception is completed is added to the cell to be transmitted to the transmission source of the cell, and when the system is switched by the system control means, the sequential numbers after the transmission which are not completed are accumulated. Immediately prior to switching the system, prioritizing the cells received from the line And it sends it to the switch. Therefore, according to the cell switching system and the cell data guarantee method of the present invention, a cell which is lost due to system switching is promptly provided by assigning a sequential number to the cell to make it a unique cell and receiving the sequential number which has been completely received. Automatically resend to. Accordingly, it is possible to provide a cell switching system and a cell data guarantee method that can perform system switching of a cell switch without losing cells even when a system switching is required due to an emergency such as a failure, and can improve reliability. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a cell switching system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a cell switching system according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a main part for explaining an example of a first method of a conventional data guarantee method at the time of system switching.

FIG. 4 is a block diagram showing a configuration of a main part for explaining an example of a second method of a conventional data guarantee method at the time of system switching.

[Explanation of symbols]

 10 system control unit 20, 30 ATM cell switch 21 switch unit, 22 sequential number notification unit, 100 to n ATM switch buffer unit 110 transmission unit 111 number assigning unit 112 retransmission control unit 113 buffer unit 120 receiving unit 121 number checking unit 122 number Holding part

Claims (12)

[Claims] 1. A duplicated cell switch means for performing cell exchange, and a cell provided for each line, sequentially given a sequential number to cells sequentially given from each line, temporarily accumulates, and stores cells to which the sequential numbers are given. Sending to each of the duplicated cell switch means, and discarding the accumulated cell and the sequential number based on the reception completion notification from the transmission destination by the sequential number, and the cell of which the reception is completed by the cell switch means. The final value for each line corresponding to the sequential number is stored, and a reception completion notification by the sequential number of the cell for which the reception is completed,
In addition to adding cells to the transmission source of that cell, at the time of system switching, the accumulated cells after the sequential numbers that have not been transmitted have priority over cells received from the line immediately after system switching. A plurality of cell switch buffer means for sending to the cell switch means, and a system control means for performing dual system switching control of the cell switch means. 2. The system control means includes means for receiving the sequential number of the transmitted cell from the cell switch means and notifying the switch buffer means of the transmission source. The cell exchange system described in. 3. The cell switch buffer means includes means for receiving the sequential number of the transmitted cell from the cell switch means and notifying the switch buffer means of a transmission source. 1. The cell exchange system according to 1. 4. A duplicated cell switch for performing cell exchange, and a cell switch buffer section provided for each line,
In a cell switching system comprising an interface for transmitting and receiving cells from the cell switch buffer unit to each of the duplicated cell switches, and a system control unit for performing system switching control of the dual system of the cell switch, The cell switch buffer unit is a number assigning unit that assigns a sequential number to the cell to generate a unique cell having a unique format different from that of the receiving cell, and a retransmission control unit that notifies the number assigning unit of the cell to be retransmitted. , And a cell transmission unit including a buffer unit that temporarily holds the transmitted unique cell, and the number that holds the latest information for each cell switch buffer unit based on the sequential number of the transmitted unique cell. Holding unit, and to the buffer unit of the cell transmission unit based on the holding number of the number holding unit Note that the cell switch has a cell receiving unit including the number check unit for discarding the unique cell, the cell switch is a means for notifying the cell receiving unit of the cell switch buffer unit of the sequential number of the unique cell that has already been transmitted. Including, the system control unit, means for performing system control of the cell switch, and receives the sequential number of the transmitted original cell from the cell switch, the cell switch buffer unit of the transmission source of the A cell switching system comprising: a means for notifying a retransmission control unit and the number holding unit; and a means for notifying a system switching to all the cell switch buffer units. 5. A duplicated cell switch for performing cell exchange, and a cell switch buffer unit provided for each line,
In a cell switching system comprising an interface for transmitting and receiving cells from the cell switch buffer unit to each of the duplicated cell switches, and a system control unit for performing system switching control of the dual system of the cell switch, The cell switch buffer unit is a number assigning unit that assigns a sequential number to the cell to generate a unique cell having a unique format different from that of the receiving cell, and a retransmission control unit that notifies the number assigning unit of the cell to be retransmitted. , And a cell transmission unit including a buffer unit that temporarily holds the transmitted unique cell, and the number that holds the latest information for each cell switch buffer unit based on the sequential number of the transmitted unique cell. Holding unit, and to the buffer unit of the cell transmission unit based on the holding number of the number holding unit Along with discarding the original cell, cell reception including the number check unit for recognizing the sequential number of the transmitted original cell from the cell switch and notifying the retransmission control unit of the cell switch buffer unit. Unit, the cell switch includes means for notifying the cell receiving unit of the cell switch buffer unit of the sequential number of the unique cell that has already been transmitted, the system control unit, system control of the cell switch A cell switching system comprising: a means for performing and a means for performing a system switching notification to all the cell switch buffer units. 6. The number assigning unit assigns a sequential number to the cell to form a unique cell, and a unit reads out the unique cell accumulated in the buffer unit according to a notification from the retransmission control unit. Including a unit for writing the unique cell transmitted to the cell switch in the buffer unit, and a unit for identifying the cell to which the sequential number should be given, wherein the retransmission control unit is the cell switch from the system control unit. A system switching notification and means for notifying the number giving unit of the cell to be retransmitted based on the notification of the sequential number of the unique cell already transmitted from the cell switch from the number holding unit, Section temporarily holds the unique cell transmitted from the number assigning section, and responds to the discard cell notification from the number checking section. The cell switching system according to any one of claims 4 and 5, comprising means for discarding the original cell. 7. The means for generating the unique cell by assigning a sequential cell number notification of the transmitted cell to a receiving cell when there is a receiving cell and to an empty cell when there is no receiving cell. 5. The method according to claim 4, wherein
The cell exchange system according to any one of 1 to 6. 8. The cell switching system according to claim 4, wherein the cell is an ATM (Asynchronous Communication Mode) cell. 9. A duplicated cell switch that performs cell exchange, and a cell switch buffer unit provided for each line,
A cell in a cell switching system including an interface for transmitting and receiving a cell from the cell switch buffer unit to each of the duplicated cell switches, and a system control unit performing system switching control of the dual system of the cell switch. In the data assurance method, a step of sequentially assigning cells to each line with sequential numbers, temporarily storing the cells in the cell switch buffer unit, and sending the cells with the sequential numbers to each of the duplicated cell switches. A step of discarding the cell and the sequential number accumulated in the cell switch buffer unit based on the reception completion notification from the transmission destination by the sequential number, and corresponding the sequential number of the cell whose reception is completed by the cell switch. The final value for each line is And a reception completion notification by the sequential number of the cell of which the reception is completed, and the addition to the cell transmitted to the transmission source of the cell, at the time of switching the system, the sequential number of which the transmission is not completed. The subsequent cell data guarantee method comprising the step of transmitting the cells accumulated in the cell switch buffer unit to the cell switch with priority over the cells received from the line immediately after switching the system. 10. The cell data according to claim 9, wherein the system control unit receives the sequential number of the transmitted cell from the cell switch and notifies the switch buffer of the transmission source of the sequential number. Guarantee method. 11. The cell switch buffer unit receives the sequential number of a transmitted cell from the cell switch and notifies the switch buffer unit of a transmission source of the sequential number. Cell data guarantee method. 12. The cell data guarantee method according to claim 9, wherein the cell is an ATM (Asynchronous Communication Mode) cell.