JPH06311176A - Cell flow switching system - Google Patents

Abstract

PURPOSE:To prevent the wrong detection of the loss and the erroneous distribu tion of a user cell, the loss and the erroneous distribution of an OAM cell at the time of duplex-switching a transmission quality monitoring OAM function on a transmission side. CONSTITUTION:Switching cell inserting circuits 10 and 11 showing the execution of duplex-switching on the transmission side are provided for each system to send a switching cell at the time of duplex-switching on the transmission side. On the other hand, switching cell detection circuits 60 and 61 are provided for each system on a reception side and at the time of receiving the switching cell, the detection of the loss and the erroneous distribution of the user cell and the loss and the erroneous distribution of the OAM cell is stopped by an OAM cell arriving next. Then, the detection of the loss and the erroneous distribution of the user cell and the loss and the erroneous distribution of the OAM cell is started again from a next OAM cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplex switching circuit for a transmission quality monitoring function in which a transmission quality monitoring function is duplicated in ATM (asynchronous transfer mode) and no malfunction occurs when a switching operation is performed.

[0002]

2. Description of the Related Art Conventional ATM (Asynchronous)
In the Transfer Mode, the redundant switching circuit for the maintenance and operation function has not been considered, but the redundant switching of the transmission line has been considered. FIG. 12 shows, for example, 19
This is the duplex switching circuit of the transmission line shown in B-526, "A Study of Non-Instantaneous Duplex Switching Method in ATM Transmission Device," 1994 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers. 5 in the figure
0 and 51 are transmission lines, 80 is 0 system FIFO, 81 is 1 system F
IFO, 90 is a selector, 500 is a cell flow on the transmitting side before branching to the 0 system, 1 system, 510 is a cell flow on the receiving side 0 system,
511 is a cell flow of the 1-system on the receiving side, 800 is a 0-system FIFO output, 801 is a 1-system FIFO output, and 900 is a selector output.

Next, the operation will be described. FIG. 13 shows FIG.
FIG. 6 is an operation explanatory diagram for describing the second aspect. In FIG. 12 and FIG. 13, the cell stream 500 is branched into two and is output from the transmission side, and the transmission line delay is added to arrive at the reception side.
The cell flow 510 and the cell flow 511 are input to the 0-system FIFO 80 and the 1-system FIFO 81. Since the cell flow 510 and the cell flow 511 do not have the same phase due to the transmission path delay difference, the cell flow 510 and the cell flow 511 cannot be input to the selector as they are and switched. In FIG. 12 and FIG. 13, the cell flow 510 and the cell flow 511 are input to the 0-system FIFO 80 and the 1-system FIFO 81, respectively, and the cell flow 51 having a large delay amount is input.
0 is output as it is as a cell flow 800 without delay, and a cell flow 511 having a small delay amount is output as a cell flow 801 with a delay of a transmission line delay difference. In this way, the cell flow 800 and the cell flow 801 have the same phase. The cell flow 800 and the cell flow 801 are input to the selector, one of them is selected and output as the cell flow 900. With the above configuration, it is possible to switch without interruption.

[0004]

The conventional non-instantaneous disconnection duplex switching circuit is configured as described above, and can cope with duplex switching of a transmission line having a transmission line delay difference. However, when the transmission quality monitoring function on the transmitting side is duplicated and switched, the following problems occur. FIG. 14 shows transmission quality monitoring O
This is a circuit in which the AM cell insertion circuit is duplicated. In the figure, 20 is a 0-system OAM cell insertion circuit, 21 is a 1-system OAM cell insertion circuit, 30 is a control circuit, and 40 is a selector. 5
0 is a transmission line. 100 is a user cell flow, 300 is 0
The output cell flow of the system OAM cell insertion circuit 20, 301 is the output cell flow of the 1-system OAM cell insertion circuit 21, and 500 is the selector output cell flow. FIG. 15 is a diagram showing the states of the cells of the cell flow 100 and the cell flow 101, u0, u1, and u.
2 ... U128 is a user cell, A0, A1, a0,
a1 is a transmission quality monitoring OAM cell. Hereinafter, the transmission quality monitoring OAM cell may be simply referred to as an OAM cell.

In FIG. 14 and FIG. 15, the 0-system OAM cell insertion circuit 20 inserts an OAM cell for each 128 user cells and outputs it as a cell stream 300, and the 1-system OAM cell insertion circuit 21 for each user cell 128 cell. The OAM cell is inserted into the cell and the cell stream 301 is output. Selector 4
0 is the selector output 500 when the cell flow 300 or the cell flow 301 is selected by the control signal 402 output from the control circuit 30.
And

FIG. 16 shows the cell format of the transmission quality monitoring OAM cell. In FIG. 16, MSN is Monit
oring cell Sequence Number
It is called r and is the sequence number of the OAM cell. M
The SN is used to detect OAM cell loss and misdelivery on the receiving side. TUC is Total User Cell nu
It is called mber and is a remainder obtained by dividing the total number of user cells output before the OAM cells are output by 65536. The TUC is used to detect user cell loss and misdelivery on the receiving side. Regarding TUC and MSN, it is being considered as an international recommendation by CCITT.

In order to make A0 and a0 completely the same cell in FIG. 15, the values of TUC and MSN in A0 are a0.
Must be equal to the values of TUC and MSN in. If the cell flow to be selected by the selector is switched while this value does not match, the values of TUC and MSN become inconsistent before and after the switching, and the receiving side erroneously detects loss or misdelivery of the OAM cell and the user cell. Will end up. In FIG. 15, the insertion position of the OAM cell of the cell flow 300 and the OA of the cell flow 301
The insertion positions of the M cells are the same (before u0 and before u128, respectively) for simplification of description, but the insertion positions also deviate unless some circuits match the insertion positions. If switching is performed in a state where the insertion position is deviated, the reception side may erroneously detect the loss or misdelivery of the user cell. Therefore, in order to perform switching without error in the configuration of FIG. 14, it is necessary to match the MSN and TUC of the OAM cell to be inserted between the 0-system and the 1-system, and to match the OAM cell insertion position. Requires a fairly large external circuit to do.

The present invention has been made in order to solve the above-mentioned problems, and it does not use a circuit for matching the MSN and TUC of the OAM cell and a circuit for matching the phase of the OAM cell at the receiving side at the time of switching. The purpose of the present invention is to obtain a duplex switching circuit with a transmission quality monitoring function that does not cause a malfunction.

[0009]

The cell flow switching system according to the present invention has the following elements. (A) Cell flow switching means having a plurality of systems, each of which inputs a cell flow to insert a monitoring cell and selects and outputs a cell flow from any one of the systems, (b) )
Switching information insertion means for adding cell flow switching information to the cell flow when changing the selection of the cell flow by the cell flow switching means, and (c) a cell flow to which the switching information is added by the switching information insertion means. Switching information detecting means for inputting and detecting switching information, and (d) inputting the cell flow to which the switching information is added by the switching information inserting means, performing cell flow monitoring processing based on the monitoring cell, and performing the switching. Cell processing means for temporarily stopping the monitoring processing of the cell flow when the switching information is detected by the information detecting means.

The cell flow switching system according to the present invention is
It is characterized in that a switching cell is created as switching information and is inserted into the cell flow.

The cell flow switching system according to the present invention is
The monitoring cell is characterized by including switching information.

The cell flow switching system according to the present invention is
The cell processing means stops the cell flow monitoring processing based on the first monitoring cell after the switching information is detected.

[0013]

In the cell flow switching method according to the first aspect of the invention, the switching information inserting means inserts the switching information when the cell flow is switched. When the cell stream having this switching information inserted therein is received, the switching information detecting means on the receiving side detects the switching information inserted in the cell stream, and the cell processing means suspends the monitoring processing performed using the monitoring cell. .
When the cell flow switching means performs the switching process, the monitoring cells created by different systems are inserted each time the switching is performed. The monitoring cell immediately after the switching may include information that does not logically match the monitoring cell before the switching. Therefore, by adding switching information to notify that there has been switching on the transmitting side and detecting this switching information on the receiving side, it is detected that there is no logical connection between the monitoring cells before and after switching. To do. In this way, it is possible to prevent the cell processing means from erroneously performing the monitoring process using the monitoring cells that are not logically connected.

In the cell flow switching method according to the second aspect of the present invention, since a switching cell is inserted in the cell flow as an example of cell flow information, the switching information detecting means monitors the cell processing means by detecting this switching cell. Suspend processing.

In the cell flow switching method according to the third aspect of the invention, the switching information is transmitted by being included in the monitoring cell inserted by the cell flow switching means, and the switching information detecting means detects the monitoring cell and The cell processing means suspends the monitoring process by detecting whether or not there is switching information therein.

Further, in the cell flow switching method according to the fourth aspect of the invention, the cell processing means stops the monitoring processing based on the monitoring cell received immediately after the switching information is detected by the switching information detecting means, thereby performing the switching. Even if a monitoring cell that does not logically match before and after the information is sent, the monitoring process is not erroneously performed.

[0017]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 has a plurality of systems, and in each system, a cell flow switching means for inputting a cell flow, inserting a monitoring cell, and selecting and outputting a cell flow from any system, 2 is a switching information insertion means for adding cell flow switching information to the cell flow when the selection of the cell flow is changed by the cell flow switching means, and 3 is a cell flow to which the switching information is added by the switching information insertion means. Enter
The switching information detecting means 4 for detecting the switching information inputs the cell flow to which the switching information is added by the switching information inserting means, performs the cell flow monitoring processing based on the monitoring cell, and the switching information detecting means detects the switching information. It is a cell processing unit that temporarily stops the monitoring process of the cell flow when the switching information is detected. 20 is a 0-system OAM cell insertion circuit, 2
Reference numeral 1 is a 1-system OAM cell insertion circuit, 40 is a selector, and 50 is a transmission path. Further, 100 is a user cell flow, 500 is a cell flow output by the selector 40, 510 is a cell flow through which the cell flow 500 passes through the transmission path 50, and 700 is a cell flow output by the cell processing means 4.

Next, the operation will be described. The cell flow switching means 1 is a circuit in which the transmission quality monitoring OAM cell insertion circuit is duplicated. The 0-system OAM cell insertion circuit 20 inserts and outputs an OAM cell for every 128 user cells and outputs the 1-system OAM cell.
The AM cell insertion circuit 21 performs OA for every 128 user cells.
Insert M cells and output. Selector 40 is 0-system OAM
The cell flow output from either the cell insertion circuit or the 1-system OAM cell insertion circuit 21 is selected and output. The switching information inserting means 2 adds the cell flow switching information to the cell flow when the selector 40 switches the cell flow. The cell flow 500 to which the switching information is added by the switching information insertion means 2 is
The switching information detecting means 3 input to the cell processing means 4 and the switching information detecting means 3 via the transmission line 50 detects the switching information inserted by the switching information inserting means 2 from the input cell stream. The cell processing means 4 receives the cell flow and performs a cell flow monitoring process based on the OAM cell. In this monitoring process, for example, as described above, the MSN is used to detect the loss or misdelivery of the OAM cell on the receiving side. Alternatively, the TUC is used to detect user cell loss or misdelivery on the receiving side.

The cell monitoring processing by the cell processing means is temporarily stopped when the switching information detecting means 3 detects the switching information. This temporary stop processing is to stop the monitoring processing of the cell flow based on the first OAM cell after the switching information is detected. The first OAM cell that arrives after the switching information is detected is the OAM cell that is output from the other one of the duplicated circuits of the cell flow switching means 1 when switching from one to the other. Therefore, it is possible to prevent erroneous detection of loss or erroneous distribution of OAM cells by stopping the first monitoring process by OAM cells from circuits of different systems. Alternatively, it is possible to prevent erroneous detection of user cell loss or erroneous distribution. Since the OAM cells from the same system are continuously received after the monitoring process based on the first OAM cell is stopped after the switching information is detected, the cell processing means 4 detects that the switching information is detected. The monitoring process is performed again from the second and subsequent OAM cells excluding the first OAM cell.

Example 2. FIG. 2 is a diagram showing another embodiment of the present invention. In the figure, 10 is a 0-system switching cell insertion circuit, 11 is a 1-system switching cell insertion circuit, and 20 is a 0-system OAM.
A cell insertion circuit, 21 is a 1-system OAM cell insertion circuit, 30 is a control circuit, 40 is a selector, 50 is a transmission line, 60 is a 0-system switching cell detection circuit, 61 is a 1-system switching cell detection circuit,
Reference numeral 70 is a 0-system OAM cell processing circuit, and 71 is a 0-system OAM cell processing circuit. 0-system switching cell insertion circuit 10, 1-system switching cell insertion circuit 11, 0-system OAM cell insertion circuit 20,
The 1-system OAM cell insertion circuit 21, the control circuit 30, and the selector 40 are circuits on the transmission side. The 0-system switching cell detection circuit 60, the 1-system switching cell detection circuit 61, the 0-system OAM cell processing circuit 70, and the 1-system OAM cell. The processing circuit 71 is a circuit on the receiving side.

Further, 100 is a user cell flow, 200 is a cell flow output from the 0-system switching cell insertion circuit 10, and 201 is 1
Cell flow output by the system switching cell insertion circuit 11; 300 is a cell flow output by the 0-system OAM cell insertion circuit 20; 301
Is the cell flow output from the 1-system OAM cell insertion circuit 21, 40
0 is output from the control circuit 30 to the 0-system switching cell insertion circuit 10 and a signal for instructing the insertion of the switching cell, and 401 is output from the control circuit 30 to the 1-system switching cell insertion circuit 11 for instructing the insertion of the switching cell. A signal, 500 is a cell flow output by the selector 40, 510 is a cell flow in which the cell flow 500 passes through the transmission path 50, and 600 is a signal indicating the detection of the switching cell output by the 0-system switching cell detection circuit 60, 60
Reference numeral 1 is a signal indicating the detection of a switching cell output by the 1-system switching cell detection circuit 61, 700 is a cell flow output by the 0-system OAM cell processing circuit, and 701 is a 1-system OAM cell processing circuit 71.
Is the cell flow output by.

FIG. 3 is an operation explanatory view for explaining the operation of FIG. In the figure, u0, u1, ... U256 are user cells, A0, A1, and A2 are OAM cells inserted by the 0-system OAM cell insertion circuit and a0, a1, and a2 are OAM cells inserted by the 1-system OAM cell insertion circuit. It is assumed that a position where no cell exists in each cell stream is a position where there is no valid cell.
All signals are described as H-significant. The operation when the transmitting side switches from the 0 system to the 1 system in FIGS. 2 and 3 will be described. In the 0-system switching cell insertion circuit 10, the signal 40
When 0 becomes significant, the switching cell C is inserted in the user cell flow 100. At this time, the signal 401 is not significant. The 0-system OAM cell insertion circuit 20 has a cell flow 20.
OAM cells A0, A1 and A2 are inserted in
Set to 0. In addition, the 1-system OAM cell insertion circuit 21 uses the cell flow 2
OAM cells a0, a1, and a2 are inserted in 01 to make cell flow 3
01. The selector 40 switches to the cell flow 300 in the cell next to the one in which the switching cell is detected, and sets the cell flow 301 as the cell flow 500 of the selector output. The cell stream 500 is delayed by the transmission line delay and becomes a cell stream 510. The 0-system switching cell detection circuit 60 and the 1-system switching cell detection circuit 61 detect the switching cell from the cell flow 510 and generate signals 600 and 601. When the signal 600 becomes H, the 0-system OAM cell processing circuit 70 stops the detection of the loss and misdelivery of the user cell and the detection of the loss and misdelivery of the OAM cell in the next OAM cell a1. With a1 as the initial value, the loss and misdelivery of the user cell and the loss and misdelivery of the OAM cell are started to be detected from the subsequent a2.

Regarding the loss or misdelivery of user cells, the number of user cells actually arrived is counted to measure the number of user cells, and the TUC of the OAM cell that has arrived and the OA that has arrived one before.
The difference between the TUCs of M cells is calculated, and when this value matches the measured number of user cells, it is assumed that there is no loss or mis-delivery, and when the measured number of user cells is smaller, loss of user cells has occurred. If the measured number of user cells is larger, it is assumed that the user cells are mis-distributed. Again O
For loss or misdelivery of AM cells, the MSN of the arriving OAM cell is compared with the MSN of the arriving OAM cell, and if the MSN of the arriving OAM cell is larger than the MSN of the arriving only one by one, It is assumed that there is no loss or misdelivery of OAM cells, that there is OAM cell loss if it is greater than 2 and that there is OAM cell misdelivery if it is 0 or less. In a1, even if TUC and MSN are not the expected values for A0 and the user cell, a
1 does not detect the loss of the user cell, the erroneous distribution, the loss of the OAM cell, and the erroneous distribution.
It is possible to prevent erroneous detection of erroneous distribution, loss of OAM cells, and erroneous detection of erroneous distribution.

Switching from the 1-system to the 0-system is similarly performed,
The 1-system switching cell insertion circuit 11 inserts the switching cell C into the user cell flow 100 when the signal 401 becomes significant. At this time, the signal 400 is not significant. The selector 40 switches to the cell flow 301 in the cell next to the one in which the switching cell is detected, and makes the cell flow 300 the cell flow 500 of the selector output. Other operations are the same as the switching from the 0-system to the 1-system, and even if the transmission side is switched, it is possible to prevent the loss of user cells, the erroneous detection of erroneous distribution, the loss of OAM cells, and the erroneous detection of erroneous distribution. it can.

It should be noted that in FIG. 3, the signal 400 is H where there is no valid cell, and the switching cell C is inserted at this position, but the signal 400 is H where there is a valid cell. In this case, the switching cell is inserted in a place where there is no valid cell after the slot of the next cell. Also, when there is a user cell at the insertion position of the OAM cell, the OAM cell is similarly inserted in a place where there is no valid cell after the cell slot. Even in such a case, the above operation is effective. Further, in FIG. 3, the OAM cells are inserted at the same position in the 0-system and the 1-system, but the above operation is effective even if they are inserted in different positions.

As described above, in this embodiment, the duplex switching circuit for the transmission quality monitoring function in ATM having the following elements has been described. (A) 0-system switching cell insertion circuit for inserting a switching cell in the user cell flow, (b) 1-system switching cell insertion circuit for inserting a switching cell in the user cell flow, and (c) output of the 0-system switching cell insertion circuit. 0 system OAM cell insertion circuit for inserting transmission quality monitoring OAM cells, (d) 1 system OAM cell insertion circuit for inserting transmission quality monitoring OAM cells at the output of 1 system switching cell insertion circuit, (e) 0 system OAM cell insertion Circuit output and 1
The output of the 0-system OAM cell insertion circuit is input, the switching cell is detected on the output of the 0-system OAM cell insertion circuit or the output of the 1-system OAM cell insertion circuit, and the output of the 0-system OAM cell insertion circuit and the 1-system OAM cell are detected. A selector for selecting and outputting any one of the outputs of the insertion circuit, and a control circuit (f) for instructing the 0-system switching cell insertion circuit to insert a switching cell and for instructing the 1-system switching cell insertion circuit to insert a switching cell. ,
(G) 0-system switching cell detection circuit that receives the output of the selector via the transmission path and detects the switching cell, (h) 1-system switching that receives the output of the selector via the transmission path and detects the switching cell Cell detection circuit, (i) receives the output of the selector via the transmission path, performs transmission quality monitoring processing,
When a switching cell is detected by the 0-system switching cell detection circuit, the 0-system OAM cell processing circuit for temporarily stopping the transmission quality monitoring processing in the next arriving transmission quality monitoring OAM cell and restarting the processing, (j) When the output of the selector via the transmission path is received and the transmission quality monitoring process is performed, and the switching cell is detected by the 1-system switching cell detection circuit, the transmission quality monitoring process of the transmission quality monitoring OAM cell that arrives next. 1-system OAM cell processing circuit for temporarily stopping and restarting.

As described above, in the duplex switching circuit of the transmission quality monitoring function in this embodiment, the 0-system switching cell insertion circuit is provided in the preceding stage of the 0-system OAM cell insertion circuit, and the 1-system OA is provided.
The 1-system switching cell insertion circuit is placed in the preceding stage of the M cell insertion circuit, and the control circuit instructs the 0-system switching cell insertion circuit to insert the switching cell and the 1-system switching cell insertion circuit to insert the switching cell. The control circuit instructs the 0-system switching cell insertion circuit to insert a switching cell when the transmission side switches from 0 system to 1 system, and the 1-system switching cell insertion circuit when the transmission side switches from 1 system to 0 system. On the other hand, the switching cell is instructed to be inserted, the selector detects the switching cell, and selects and outputs the cell flow of the system other than the system detected from the cell next to the switching cell. On the receiving side, 0 system switching cell detection circuit and 1
A system switching cell detection circuit is provided. When the system 0 switching cell detection circuit detects a switching cell from the transmission line, it notifies the system 0 OAM cell processing circuit that the switching cell has been detected, and the system 0 OAM cell processing circuit switches. When it is notified that a cell has been detected, detection of loss or misdelivery of an OAM cell or a user cell in the next OAM cell is temporarily terminated, and the next OAM cell is detected.
After the cell arrives, the loss and misdelivery of the OAM cell and the user cell are detected again. The 1-system switching cell detection circuit and the 1-system OAM cell processing circuit perform similar operations.

As described above, according to this embodiment, a cell indicating that switching has occurred is generated on the transmitting side, and when this is detected on the receiving side, loss of the user cell due to the next arriving OAM cell or By once stopping the detection of misdelivery, the loss of OAM cells and the detection of misdelivery, and starting to detect the loss and misdelivery of user cells and the loss and misdelivery of OAM cells from the next OAM cell, It is possible to prevent loss of user cells, erroneous detection of erroneous distribution, loss of OAM cells, and erroneous detection of erroneous distribution.

Example 3. FIG. 4 is a diagram showing another embodiment of the present invention. In the figure, 0-system switching cell insertion circuit 10
At the instruction of the control circuit 30, the switching cell is inserted into the cell flow 100 and is output as the cell flow 200, and the switching signal 210 is made significant while the switching cell is being output.
The 1-system switching cell insertion circuit 11 inserts a switching cell into the cell flow 100 according to an instruction from the control circuit 30 and outputs it as the cell flow 201, and makes the switching signal 211 significant while the switching cell is being output. The selector 40 outputs the cell flow 5 according to the switching signal 210 and the switching signal 211.
As 00, either the cell flow 300 or the cell flow 301 is selected and output. When there is a delay between the input and output of the 0-system OAM cell insertion circuit 20, the 0-system switching cell insertion circuit delays this amount and makes the switching signal 210 significant. The same applies to the switching signal 211. The other configurations and operations are the same as those in the first embodiment, and the description thereof will be omitted.

When the selector 40 switches from the 0 system to the 1 system, the switching can be performed at the same timing as in the second embodiment if the switching is performed in the next cell in which the switching signal 210 becomes significant. When switching from the 1-system to the 0-system, the switching is performed in the next cell where the switching signal 211 becomes significant. Other operations are the same as those in the second embodiment, and when the transmitting side performs switching as in the second embodiment,
Loss of user cells, false detection of misdelivery and loss of OAM cells,
It is possible to prevent erroneous detection of misdelivery.

In the second embodiment, the selector 40 detects the switching cell in order to detect the switching timing, but according to this embodiment, the detection of the switching cell is unnecessary.

As described above, in this embodiment, in the duplex switching circuit of the transmission quality monitoring function in ATM, the 0-system switching cell inserting circuit indicates, when the switching cell is inserted, the 0-system switching signal indicating the insertion. When the switching cell is inserted, the 1-system switching cell insertion circuit makes the 1-system switching signal indicating the insertion significant, and the selector sets 0.
It is characterized in that either the output of the 0-system OAM cell insertion circuit or the output of the 1-system OAM cell insertion circuit is selected and output according to the system switching signal and the 1-system switching signal.

Example 4. FIG. 5 is a diagram showing another embodiment of the present invention. In the figure, 0-system OAM cell insertion circuit 20
Is a function for generating an OAM cell, inserting the OAM cell in the user cell stream 100 and outputting it as the cell stream 300, and a signal 40 for instructing the insertion of the switching information output by the control circuit 30.
It has a function of inserting switching information into the OAM cell with an instruction of 0. The 1-system OAM cell insertion circuit 21 generates an OAM cell, inserts the OAM cell in the user cell stream 100, and
01 and the function of inserting the switching information into the OAM cell according to the instruction of the signal 401 that instructs the insertion of the switching information output from the control circuit 30. The 0-system switching information detection circuit 60 detects the OAM cell on the cell stream 500 in which the switching information is inserted, and a signal 600 indicating that it has been detected.
Is output. The 1-system switching information detection circuit 61 uses the cell flow 50
The OAM cell in which the switching information on 0 is inserted is detected, and the signal 601 indicating the detection is output. Others are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 6 is an operation explanatory view for explaining the operation of FIG. The operation when the transmitting side switches from the 0 system to the 1 system in FIGS. 5 and 6 will be described. When the control circuit 30 wants to switch to the 1-system, a signal 40 for instructing the insertion of switching information
Make 0 significant. The 0-system OAM cell insertion circuit outputs the signal 400
Becomes significant, the switching information is inserted into the OAM cell A1 to be output next. Selector 40 is OAM on cell flow 300
OAM cell A1 in which cell is monitored and switching information is inserted
When cell is detected, the cell to be output next is switched to the 1-system, and the cell flow 301 is output as the cell flow 500 of the selector output.
The cell flow 500 receives the delay of the transmission line delay and the cell flow 510
Becomes The 0-system switching information detection circuit 60 and the 1-system switching information detection circuit 61 detect the OAM cell A1 in which the switching information is inserted from the cell flow 510 and generate the signal 600 and the signal 601. The 0-system OAM cell processing circuit 70 detects loss or misdelivery of a user cell when the signal 600 becomes H, and OA
Stop detection of loss or misdelivery of M cell and insert O
Loss or mis-delivery of user cell from the next OAM cell with MSN or TUC of AM cell a2 as initial values, and OA
Start detecting loss and misdelivery of M cells.

Switching from the 1-system to the 0-system is similarly performed,
The 1-system OAM cell insertion circuit 21 inserts the OAM cell a1 in which the switching information has been inserted into the user cell flow 100 when the signal 401 becomes significant. At this time, the signal 400 is not significant. Selector 40 is cell flow 301
Then, switching is performed in the cell next to the one in which the switching cell is detected, and the cell flow 300 is used as the cell flow 500 of the selector output. Other operations are exactly the same as the switching from the 0 system to the 1 system, and even if the transmission side is switched, it is possible to prevent the loss of the user cell, the erroneous detection of erroneous distribution, the loss of the OAM cell, and the erroneous detection of erroneous distribution. You can

Incidentally, in FIG. 6, OA is performed in a place where there is no valid cell.
When the M cell is inserted, but there is a valid cell in the place where the OAM cell is to be inserted, the OAM cell is inserted in the place where there is no valid cell after the next cell slot.
Even in such a case, the above operation is effective. Further, in FIG. 6, the position where the OAM cell is inserted is the same for the 0-system and the 1-system, but the above operation is effective even if they are inserted at different positions.

As described above, in this embodiment, the duplex switching circuit for the transmission quality monitoring function in ATM having the following elements has been described. (A) 0-system OAM cell insertion circuit that inserts a transmission quality monitoring OAM cell into the user cell stream and also inserts switching information into the transmission quality monitoring OAM cell, and (b) inserts a transmission quality monitoring OAM cell into the user cell stream. , Again transmission quality monitoring OAM
1-system OAM cell insertion circuit for inserting switching information into cells,
(E) The output of the 0-system OAM cell insertion circuit and the output of the 1-system OAM cell insertion circuit are input, and the transmission quality monitoring OAM cell output by the 0-system OAM cell insertion circuit or the transmission output by the 1-system OAM cell insertion circuit output Depending on the switching information of the quality monitoring OAM cell, the output of the 0 system OAM cell insertion circuit and the 1 system OA
A selector for selecting and outputting the output of the M cell insertion circuit,
(F) A control circuit for instructing the 0-system OAM cell insertion circuit to insert switching information and a 1-system OAM cell insertion circuit for instructing insertion of switching information, and (g) receiving the output of the selector via the transmission path. , 0-system switching information detection circuit for detecting switching information in transmission quality monitoring OAM cell,
(H) 1-system switching information detection circuit that receives the output of the selector via the transmission path and detects the switching information in the transmission quality monitoring OAM cell; (i) receives the output of the selector via the transmission path and transmits The quality monitoring process is performed, and when the switching information is detected by the 0-system switching information detection circuit, the transmission quality monitoring process is temporarily stopped and restarted, and the 0-system OAM cell processing circuit, (j) the selector via the transmission path The system 1 OAM cell processing circuit that receives the output of the system 1 and performs the transmission quality monitoring process. When the system 1 switching information detection circuit detects the switching information, the transmission quality monitoring process is temporarily stopped and restarted.

The duplex switching circuit of the transmission quality monitoring function in this embodiment is provided with a function of inserting switching information into an OAM cell in the 0-system OAM cell insertion circuit and the 1-system OAM cell insertion circuit, for example. The control circuit gives an instruction to insert switching information to the cell insertion circuit and an instruction to insert switching information to the 1-system OAM insertion circuit, and the control circuit inserts 0-system OAM cell when the transmitting side switches from 0-system to 1-system. The switching instruction is given to the circuit, and when the transmitting side switches from the 1-system to the 0-system, the 1-system OAM cell insertion circuit is instructed to insert the switching information, and the selector is the switching inserted in the OAM cell. Information is detected, and a cell flow of a system other than the system in which the switching information is detected is selected from the next cell and output to the transmission path. The 0-system switching information detection circuit notifies the 0-system OAM cell processing circuit when an OAM cell containing switching information is detected from the transmission line, and the 0-system OAM cell processing circuit informs the OAM cell or user of the next OAM cell. Detection of cell loss and misdelivery is once terminated, and loss and misdelivery of OAM cells and user cells are detected again when the next OAM cell arrives. The 1-system switching information detection circuit and the 1-system OAM cell processing circuit perform similar operations.

According to this embodiment, when switching occurs on the transmitting side, an OAM cell in which switching information is inserted is generated,
On the receiving side, when the switching information detection circuit detects the OAM cell in which the switching information is inserted, the OAM cell processing circuit temporarily ends the detection of the loss or misdelivery of the OAM cell or the user cell by the next OAM cell. By detecting the loss or mis-delivery of the OAM cell or user cell again after the next OAM cell comes, the loss or mis-delivery of the OAM cell or user cell at the receiving side at the time of duplex switching of the OAM function is performed. The false detection of can be prevented.

Example 5. FIG. 7 is a diagram showing another embodiment of the present invention. In the figure, 0-system OAM cell insertion circuit 20
In response to an instruction from the control circuit 30, the OAM cell in which the switching information is inserted is inserted into the cell flow 100, and is output as the cell flow 300. The switching signal 310 is output while the OAM cell in which the switching information is inserted is output. Make it significant. 1 series O
The AM cell insertion circuit 21 receives a cell flow 1 according to an instruction from the control circuit 30.
The OAM cell in which the switching information is inserted in 00 is output as the cell stream 301, and the switching signal 311 is output while the OAM cell in which the switching information is inserted is output.
To be significant. The selector uses the switching signal 310 and the switching signal 311 as the cell flow 500 to output the cell flow 300.
And cell flow 301 are selected and output. The other configurations and operations are the same as those in the second embodiment, and the description thereof will be omitted.

When the selector switches from the 0 system to the 1 system, switching can be performed at the same timing as in the second embodiment by switching in the next cell in which the switching signal 310 becomes significant. When switching from the 1-system to the 0-system, the switching is performed in the next cell where the switching signal 311 becomes significant. Other operations are similar to those in the fourth embodiment,
When the transmission side performs switching as in the fourth embodiment, it is possible to prevent the loss of user cells, the erroneous detection of erroneous distribution, the loss of OAM cells, and the erroneous detection of erroneous distribution.

In the fourth embodiment, the selector detects the OAM cell in which the switching information is inserted in order to detect the switching timing, but according to this embodiment, the selector 4
It is not necessary to detect the OAM cell in which the switching information of 0 is inserted.

As described above, in this embodiment, in the duplex switching circuit of the transmission quality monitoring function in ATM, the 0-system OA is used.
The M cell insertion circuit is a transmission quality monitor that inserts switching information.
When AM is output, the 0-system switching signal is made significant and 1
The system switching cell insertion circuit, when the switching cell is inserted,
The 1-system switching signal indicating the insertion is made significant, and the selector selects either the output of the 0-system OAM cell insertion circuit or the output of the 1-system OAM cell insertion circuit according to the 0-system insertion signal and the 1-system insertion signal. It is characterized by outputting.

As described above, this embodiment generates an OAM cell in which switching information indicating that switching has occurred is inserted on the transmitting side, and when this is detected on the receiving side, the next arriving OAM cell is generated. User cell loss and mis-delivery detection, OAM cell loss and mis-delivery detection are stopped, and user cell loss and mis-delivery and OAM cell loss from the next arriving OAM cell. By starting to detect the outflow or misdelivery, it is possible to prevent the loss of the user cell, the misdetection of the misdelivery, and the loss of the OAM cell and the misdetection of the misdelivery.

Example 6. FIG. 8 is a diagram showing another embodiment of the present invention. In the embodiment described above, the case where the receiving side is also a dual system has been described, but as shown in FIG. 8, the circuit on the receiving side does not need to be a dual system, and is configured by only one system. But it doesn't matter. In FIG. 8, 7
Reference numeral 0 is an OAM cell processing circuit, which constitutes a processing circuit composed of one system. A switching cell detection circuit 60 detects a switching cell inserted by the 0-system switching cell insertion circuit or the 1-system switching cell insertion circuit 11 to perform OAM.
This is a circuit that outputs the detection to the cell processing circuit.

Example 7. FIG. 9 is a diagram showing another embodiment of the present invention. In the above-mentioned FIG. 2, when the 0-system switching cell insertion circuit 10 and the 1-system switching cell insertion circuit 11 input the user cell flow 100 and output it to the 0-system OAM cell insertion circuit 20 and the 1-system OAM cell insertion circuit 21. However, as shown in FIG. 9, the 0-system switching cell insertion circuit 10 and the 1-system switching cell insertion circuit 11 include a 0-system OAM cell insertion circuit, a 1-system OAM cell insertion circuit 21, and a selector 40.
It doesn't matter if they are in between.

Example 8. FIG. 10 is a diagram showing another embodiment of the present invention. In FIG. 2 described above, the 0-system switching cell inserting circuits 10 and 1 are used as circuits for inserting the switching cells.
Although the case where two system switching cell insertion circuits 11 are present has been described, one switching cell insertion circuit 10 may be provided as shown in FIG. When the switching cell insertion circuit is duplicated as shown in FIG. 2, even if one fails, the other works, so that the reliability can be increased.
On the other hand, when only one switching cell insertion circuit is provided as shown in FIG. 10, the reliability is inferior, but the circuit configuration is simplified.

Example 9. FIG. 11 is a diagram showing another embodiment of the present invention. The feature of FIG. 11 is that only one switching cell insertion circuit 10 is provided and this switching cell is inserted when any one of the cell flows is selected by the selector. The control circuit 30 supports the insertion of the switching cell with respect to the switching cell insertion circuit 10. The switching cell insertion circuit 10 inserts a switching cell into the cell flow selected by the selector.

Example 10. 8 to 11 described above are described as examples of improvement of the configuration shown in FIG. 2, but the configuration shown in FIG. 4 may be improved as shown in FIGS. 8 to 11. Further, the above-described improvement examples of FIGS. 8 to 11 may be cases where the configurations shown in FIGS. 5 and 7 are improved.

[0050]

As described above, according to the present invention, in the cell flow switching circuit such as the duplex switching circuit of the transmission quality monitoring OAM function, the receiving side can detect the switching of the transmitting side, so that the loss of the user cell, False positives and OAM
It is possible to prevent cell loss and erroneous detection of erroneous distribution.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing the operation of the above embodiment.

FIG. 4 is a diagram showing an embodiment of the present invention.

FIG. 5 is a diagram showing an embodiment of the present invention.

FIG. 6 is a diagram showing the operation of the above embodiment.

FIG. 7 is a diagram showing an embodiment of the present invention.

FIG. 8 is a diagram showing an embodiment of the present invention.

FIG. 9 is a diagram showing an embodiment of the present invention.

FIG. 10 is a diagram showing an embodiment of the present invention.

FIG. 11 is a diagram showing an embodiment of the present invention.

FIG. 12 is a diagram showing transmission line duplex switching in a conventional ATM.

FIG. 13 is a diagram showing an operation of transmission line duplex switching in a conventional ATM.

FIG. 14 is a diagram showing a problem when the transmission quality monitoring OAM function is duplicated.

FIG. 15 is a diagram showing the operation of FIG. 14;

FIG. 16 is a diagram showing a format of a transmission quality monitoring OAM cell.

[Explanation of symbols]

1 0 system switching cell insertion circuit 2 1 system switching cell insertion circuit 3 0 system OAM cell insertion circuit 4 1 system OAM cell insertion circuit 10 0 system switching cell insertion circuit 11 1 system switching cell insertion circuit 20 0 system OAM cell insertion circuit 21 1-system OAM cell insertion circuit 30 Control circuit 40 Selector 50 Transmission line 60 0-system switching cell detection circuit 61 1-system switching cell detection circuit 70 0-system OAM cell processing circuit 71 0-system OAM cell processing circuit 100 User cell flow 200, 201, 300,301,500,510,7
00,701 Cell flow 400,401,600,601 Signal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04L 12/26 8732-5K H04L 11/20 Z

Claims (4)

[Claims] 1. A cell flow switching method having the following elements: (a) a plurality of systems, each of which inputs a cell flow to insert a monitoring cell, and a cell from any one of the systems. Cell flow switching means for selecting and outputting a flow, (b) switching information inserting means for adding cell flow switching information to the cell flow when the selection of the cell flow is changed by the cell flow switching means, (c) Switching information detecting means for inputting the cell flow added with the switching information by the switching information inserting means and detecting the switching information, (d) inputting and monitoring the cell flow added with the switching information by the switching information inserting means Cell processing means for performing cell flow monitoring processing based on the cell for use and temporarily stopping the cell flow monitoring processing when the switching information is detected by the switching information detecting means. 2. The cell flow switching system according to claim 1, wherein said switching information inserting means creates a switching cell as the switching information and inserts it into the cell flow. 3. The switching information inserting means includes switching information in the monitoring cell.
Cell flow switching method described. 4. The cell flow switching system according to claim 1, wherein the cell processing means stops the monitoring process of the cell flow based on the first monitoring cell after the switching information is detected.