JP2002077189A - Important call control system in atm switching network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an important call control system in an ATM switching network capable of realizing a stable network system by changing a bypass system and suppressing the disconnections of important calls between END terminals as much as possible. SOLUTION: ATM switching devices 1-6 identify the important call at the time of a call connection request and give it priority over a general call until call setting completion. After the call setting completion, the ATM switching devices 1-6 perform monitoring by fault notification by OAM cells. The ATM switching devices 1-6 perform classification into the faults of three stages from fault duration, respectively define the restoration method of the call, perform it between a fault detection station and a terminating terminal housing station at the time of bypassing and thus, relieves the call between the END terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an important call control system in an ATM switching network, and more particularly to an ATM (Asynchronous ATM).
The present invention relates to a connection control method for a call in an on-transfer mode switching device.

[0002]

2. Description of the Related Art Conventionally, as a call connection method between terminals in an ATM network, a fixed connection PVC (Permane) is used.
nt Virtual Circuit) and a dynamically connected SVC (Switched Virtual Circuit)
al Circuit).

[0003] In the PVC, a maintenance person fixedly connects an incoming logical channel and an outgoing logical channel for each switching device, so that a call can be quickly restored after a failure is recovered. It is impossible to bypass the time. Also,
In PVC, a maintenance person must intervene in setting a network path.

In SVC, CCITT (Internat
ionical Telephoneand Telegr
aph Consultative Committee
e: The call setup can be automatically performed because the call setup is dynamically performed from the calling terminal to the called terminal using the signaling function of T2931 indicated in the (ITU-T) recommendation.

[0005] In addition, in the SVC, a call can be reset from the calling terminal in the event of a failure, so that a detour during the failure is possible. However, since signaling is performed by software control of the switching device, there is an overhead until a call is established,
In addition, since call monitoring is also performed by polling control of call processing, communication starts all at once, and when a heavy load occurs that temporarily causes congestion, if a call cannot be established or the connected call is disconnected. May be lost.

[0006] Further, in the SVC, if a relay station or a relay line becomes faulty, the current system uses END-END.
The path between them is once disconnected, and a detour is realized by a reconnection request from the terminal.

[0007] In an actual ATM network, when it is necessary to communicate with an unspecified number of terminals, a server for managing the terminals is prepared, and the terminals use the SVC system when connecting to the network. The call is always connected, and when communication with a specific terminal occurs, the call connection to the terminal is performed by the same SVC method based on information from the server.

As described above, in a conventional network system, both an important call which is always connected and a call which is connected for performing temporary communication between terminals are realized by the SVC system. .

In this conventional ATM switching system,
There is a technique in which a switch sets a priority level on a call control signaling message, changes the order of call processing and sets a priority, and uses a line bandwidth with priority after a call is established. In this case, if the server call is defined as a high priority level, the priority call setting allows the ATM cells to be transferred with priority even after the call is established. This technique is disclosed in Japanese Patent Laid-Open No. 11-863.
No. 2 discloses this.

As another technique, OAM (Ope)
ratio Administration and
(Maintenance) cell or an OAM loopback cell for monitoring the bus and a route reselection method using a priority method. This technology is disclosed in
No. 1,115,420 and JP-A-9-238146.

Further, as another technique, there is a method in which a routing header is added to an ATM cell and routing is performed on a cell basis. This technology is disclosed in
No. 307554.

Further, as another technique, there is a method of restoring from a detour route using a maintenance center. This technique is described in JP-A-6-37783.

[0013]

In the above-mentioned conventional system, important server calls and temporary communication calls require
Since call management after call setup is treated equally, even if a network failure occurs, even if it is temporary, if only the call to the server is disconnected, the terminal will be disconnected from the network Becomes Then, when all communication calls are disconnected and the server call is restored, all communication calls are reset at the same time, making network communication unstable due to temporary failure. There is.

Further, if congestion due to a high load occurs temporarily due to the simultaneous call disconnection and the simultaneous reconnection, connection to a server call may be rejected, and the above problem is repeated. There is also a problem that a high load is easily sustained in the switch.

According to the technique described in the above-mentioned publication, it is possible to preferentially reconnect important calls by using the priority of the change of the detour method and the call by the network monitoring by the OAM or the maintenance center. Since the setting is performed, a similar problem occurs with respect to the above problem.

Further, in the technique described in Japanese Patent Application Laid-Open No. 9-307554, a routing header is added to a cell, so that the cell size increases and the band itself becomes narrower. Since the overhead of data transfer occurs and a high load is easily sustained in the switch, the above problem cannot be solved.

On the other hand, if congestion due to a high load occurs temporarily due to the simultaneous call disconnection and the simultaneous fine connection, the connection to the server call may be rejected, and the above problem is repeated. Since the congestion is maintained, there is a problem that a high load on the switch is likely to be maintained when the number of terminals is large.

Further, since the SVC call failure is detected by the polling control of the signaling, if the above-mentioned high load occurs, the polling control becomes impossible and the connected server call may be disconnected. Therefore, when the number of terminals is large, there is a problem that the high load of the switch is likely to be maintained.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to minimize the disconnection of important calls between END terminals by changing the bypass method, and to realize an ATM switching system capable of realizing a stable network system. It is to provide an important call control method in a network.

[0020]

An important call control method in an ATM switching network according to the present invention is an important call control method in an ATM switching network in which data communication between a terminal and a server is performed in an asynchronous transfer mode via a plurality of switching devices. A PVC (Perman) which is a control method in which call setting information is fixedly connected as important call path information after a call is established for at least an important path which must always be connected to the server.
Each of the plurality of switching devices is provided with a configuration for static management similar to that of an ent virtual circuit (ent Virtual Circuit) so that a call is not easily disconnected between END terminals when a network failure occurs.

That is, the important call control method in the ATM switching network of the present invention gives priority to an important call which must always be connected to the conventional connection, and monitors the failure after the connection by the ATM cell. The monitoring method that is notified by is used.

Further, in the important call control method in the ATM switching network according to the present invention, when a failure occurs in the network, a three-stage recovery method is provided from the continuation time to promptly recover the call and disconnect the call between the END terminals. The system that is not performed is realized.

Hereinafter, a call set by this method is called an important call, and a call set by a conventional method is called a general call. Also, the above-mentioned monitoring method is changed to OAM (Operati
onAdministration and Main
(Tenance) Described in a format using cells.

First, when it is necessary to connect an important call that affects other calls, the terminal transmits a request as an important call. The exchange receiving this request makes the connection using the important call connection method.

In the important call setting method, a call connection is performed prior to a general call until the setting is completed. After completion of the important call connection, the polling control by signaling is not performed, and the monitoring is performed by the OAM cell failure notification. After the setting of the important call is completed, the station that detects the line failure of the path or receives the failure notification cell by the OAM sets the primary failure monitoring timer to determine whether the failure line is a failure due to a primary failure. I do.

Until the primary failure monitoring timer times out, no rerouting is performed to prioritize call recovery as a primary failure. If the failure has not been recovered even after the timeout, when the failed line is in the destination direction, the alternate call is temporarily set as a general call. Further, the destination terminal accommodating station that has received the alternate call performs connection switching to the alternate call path for the path to the already connected terminal. Therefore, the path is not disconnected for both the calling terminal and the called terminal. Also,
In this state, the original route path is not cut by another relay station.

Next, the fault detecting station sets and monitors a fixed fault timer to determine whether or not the fault is a fixed fault. Until the fixed failure timer times out, the secondary failure is determined to be in progress. If the failure is recovered in this state, the bypass line is disconnected and the original old route path is switched. The destination side also switches to the original call route when the detour line is disconnected.

If the failure is not recovered by the failure detecting station even when the fixed failure timer times out, the recovery to the old route path is abandoned as the fixed failure state, and the current detour route is continued to be used. For this reason, the original old route path is disconnected at each station. In addition, the fault detecting station that has established the alternate call sends an important call setting switching instruction to change the alternate route from a general call to an important call. Upon receiving the path setting switching instruction, the relay station transfers the instruction to the destination along the bypass route and changes the operation to an important call path.

If the fault is a system fault in the relay station and it must be recovered by restarting the system at that station, the important call information is automatically saved when the fault occurs. After the call is recovered, the call can be promptly recovered from the information. Also, if the system recovers after the network disconnects the relevant important call path as a fixed failure, the saved path must be deleted and disconnected, so the absolute time is saved together with the important call information when a failure occurs. In advance, when the system is restored, the system down time is calculated from the data, and if the fixed failure time is exceeded, the important call path owned by the user is deleted.

By executing the above functions, the priority setting of the call for the server and the disconnection of the path are less likely to occur, and a network that is resistant to software processing at the time of setting the path and that is resistant to congestion and obstacles can be constructed.

[0031]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ATM switching device according to one embodiment of the present invention. FIG.
In the ATM switching device 1, the exchange control processing unit 11
Control path gateway device 12 and switch control device 1
3, a line control device 14, and a clock device 15. The line controller 14 is a line communication controller 14.
1, the buffer control unit 142, and the OAM (Operat
ion Administration and Ma
control) 143 and the OAM CEL
It is composed of an L monitoring extraction unit 144 and a line failure detection unit 145.

The exchange control processing unit 11 is a software processing unit included in a processor (not shown) of the ATM switching device 1, and includes a failure management processing unit 111 and an SVC (Switch).
d Virtual Circuit) control processing unit 11
2 and PVC (Permanent Virtual)
(Circuit) control processing unit 113, system down time detection processing unit 114, important call path control processing unit 115
It is composed of

The failure management processing unit 111 has a function of managing a failure. When a failure occurs in the ATM switching device 1, the failure management processing unit 111 transmits an OAM cell to notify the failure notification.
Notifying the control unit 143 and notifying the important call path control processing unit 114.

Further, the fault management processing unit 111 has a function of monitoring a line fault in which a line fault is detected by hardware, a fault notification by an OAM cell, and its recovery. When the fault management processing unit 111 receives the line fault notification from the hardware,
This is notified to the SVC control processing unit 112 and the important call path control processing unit 114.

When the failure management processing unit 111 receives the failure notification by the OAM cell, it determines whether or not the CELL (cell) is an adjacent station, and if it is an adjacent station, notifies the important call path control processing unit 114.

The SVC control processing unit 112 has a function of performing the conventional SVC control, and the MSG (message) call control unit 1
121 and a routing control unit 1122. SVC
The control processing unit 112 performs SVC protocol control and analyzes a message used in the protocol.

When the received message is an important call connection request or an important call connection response, the SVC control processing unit 112 performs the connection operation with the conventional SVC as before. However,
Since the established path is an important call, monitoring by polling is not performed. Further, the SVC control processing unit 112 notifies the important call path control processing unit 115 of the path information.

The SVC control processing unit 112 performs the connection operation with the conventional SVC even when the received message is a detour setting request. When the local station is the terminating terminal, the SVC control processing unit 112 does not transfer the information to the terminal (not shown) or the server (not shown), notifies the important call path control processing unit 115, and sends a detour setting response message. I will send it back.

The SVC control processing unit 112 establishes a connection with the conventional SVC even when the received message is a detour setting response. In this method, failure monitoring by polling is performed after a path is established, as in the conventional method. When the local station is the detour setting request transmitting station, the SVC control processing section 112 notifies the important call path control processing section 115.

When the received message is a detour release request, the SVC control processing unit 112 disconnects the connection with the conventional SVC. If the local station is the terminating terminal station, the SVC control processing unit 112 returns the detour setting response message after notifying the important call path control processing unit 115 without transferring the terminal or the server.

Even when the received message is a bypass release response, the SVC control processing unit 112 performs the conventional operation of establishing a connection with the SVC. In this method, failure monitoring by polling is performed after a path is established, as in the conventional method. The SVC control processing unit 112, when the own station is a detour setting request transmitting station,
The important call path control processing unit 115 is notified.

When the received message is a detour release request, the SVC control processing unit 112 performs a conventional operation of disconnecting the SVC from the connection. If the local station is the terminating end station, the SVC control processing section 112 returns a detour setting response message after notifying the important call path control processing section 115 without transferring the terminal or server.

Even when the received message is a bypass release response, the SVC control processing unit 112 performs the conventional operation of establishing a connection with the SVC. In this method, failure monitoring by polling is performed after a path is established, as in the conventional method. The SVC control processing unit 112, when the own station is a detour setting request transmitting station,
The important call path control processing unit 115 is notified.

If the received message is an important call change notification request, the SVC control processing unit 112 transmits the message to the set detour route path. When the local station is the terminating terminal, the SVC control processing unit 112 returns the important call change notification response message after notifying the important call path control processing unit 115 without transferring the terminal to the terminal or the server.

If the received message is an important call change notification response, the SVC control processing unit 112 notifies the important call path control processing unit 115 and transfers the message to the bypass route. Since the established path is an important call, the SVC control processing unit 112
Do not monitor by polling.

When the received message indicates an important call disconnection instruction, the SVC control processing unit 112 performs a conventional operation of disconnecting the SVC from the connection, and notifies the important call path control processing unit 115 of the operation. When the SVC control processing unit 112 receives the detour path routing request from the important call path control processing unit 115,
Routing is performed for the destination terminal starting from the logical port opposite to the failed line.

When the received message is a message relating to an important call, the SVC control processing unit 112 performs processing at a higher priority than other general SVC call control being processed in parallel.

The PVC control processing unit 113 is a conventional PVC process, and sets and deletes a logical path for the hard buffer and the switch control. The PVC control processing unit 113 includes a PVC setting processing unit 1131 and a PVC path deletion processing unit 1132, and their functions are the same as the conventional functions.

The system down time detection processing unit 114 is a processing unit that calculates the system down time when the system is restarted. The system down time detection processing unit 114 saves the failure occurrence time in the secondary storage medium 16 when a system failure such as a system failure occurs. Further, at the time of recovery or resumption, the system down time detection processing unit 114 calculates the system down time from the current time and the saved time, and notifies the important call path control processing unit 115 of the system down time.

The important call path control processing section 115 is a processing section for performing control specific to an important call when a path is connected. When notified from the SVC control processing section 112, the message content of the notification is an important call setting request message or an important call setting request message. When it is a call change request, the logical port information at both ends, the request direction, and the destination terminal address information are set.

When the local station is a destination and an important call change request, the important call path control processing unit 115 transmits an important call disconnection request to the fixed failure station in order to delete the old route path. A transmission request is made to the SVC control processing unit 112 at first.

If the message content is an important call setting response or an important call change response, the important call path control processing unit 115 determines that the important call path has been established. Notify section 113.

When the content of the message is a bypass call release request message and the own station is the destination, the important call path control processing unit 115 resets the path of the normal route that has already been set up beforehand, and establishes the bypass route and the destination terminal. A notification is sent to the PVC control processing unit 113 to set a path to the logical port.

The important call path control processing unit 115 resets the path of the normal route that has been previously established even when the message content is the alternate call release response message and the own station is the alternate call release request message transmitting station. A notification is sent to the PVC control processing unit 113 in order to set a path to the bypass route and the logical port of the destination terminal.

If the content of the message is an important call disconnection message, the important call path control processing unit 115 deletes the already established route path by the PVC control control processing unit 1.
13 is notified.

When notified by the fault management processing unit 111, the important call path control processing unit 115 searches for a logical port related to the line, and if the relevant faulty line is a called side in a station adjacent to the faulty station, a temporary fault occurs. Set the monitoring timer. In this state, the important call path control processing unit 115
When the failure recovery notification is received from the first, the temporary failure monitoring timer is canceled. When the temporary failure monitoring timer times out, the important call path control processing unit 115 notifies the SVC control processing unit 112 to transmit a bypass path setting request.

Thereafter, the important call path control processing unit 115 sets a fixed fault monitoring timer. In this state, when the important call path control processing unit 115 receives the failure recovery notification, the important call path control processing unit 115 requests the SVC control processing unit 112 for a bypass call release request message request to disconnect the bypass path, and then releases the fixed failure monitoring timer. . When the fixed failure monitoring timer times out, the important call path control processing unit 115 requests the SVC control processing unit 112 to issue an important call change request in order to use the already established detour path as a regular path route.

The important call path control processing unit 115 deletes the original old circuit path route information and transmits an important call deletion instruction to the faulty station to the SVC control processing unit 112 in order to completely delete the old path route. Request.

When the important call path control processing unit 115 receives the restart notification from the system down time detection processing unit 114, if the system time does not exceed the fixed failure monitoring time, the important call path control processing unit 115 reads out all saved important call path information, A state in which the path needs to be reset is notified to the PVC control processing unit 113 to perform switching setting of the logical ports at both ends.
If the notified system down time exceeds the fixed failure monitoring time, the important call path control processing unit 115 deletes all the important call paths.

When the important call path control contents are changed, the important call path control processing unit 115 stores the information in the secondary storage medium 16 when a failure occurs so that the information can be restored even after the system failure is restored. To save.

As described above, the AT according to one embodiment of the present invention
Although the configuration of the M exchange device 1 has been described, in FIG.
Control pass gateway device 12, switch control device 1
3, the line control device 14 and the clock device 15 are illustrated for the interface between software and hardware, but their operations are not different from the conventional operations, and are well known to those skilled in the art. Since it is not directly related to the present invention, a detailed description of its configuration and operation will be omitted. Further, since the operation on the terminal side only identifies and transmits an important call and a general call, a description of the operation is also omitted.

FIG. 2 is a block diagram showing a system configuration of an ATM switching network according to one embodiment of the present invention.
In FIG. 2, an ATM switching network according to an embodiment of the present invention comprises ATM switching devices 1 to 6, terminals 7, 9 and a server 8, and the terminals 7, 9 are connected to a server to join the network. 8 is accommodated.

When the terminal 7 needs to communicate with the terminal 9 again after the terminal 7, 9 is connected to the server 8,
A call connection is made to the terminal 9. In this case, the path between the terminal 7 and the terminal 9 performs call connection only during communication,
A call is always connected to each terminal 7, 9 to indicate that the call connection with the server 8 has joined the network. Further, if the path between the terminal 7 and the server 8 is disconnected during communication between the terminal 7 and the terminal 9 due to a failure or the like, the terminal 7
The call between the terminal and the terminal 9 is also disconnected, and the communication is interrupted.

In one embodiment of the present invention, the terminal 7 is connected to the server 8
In order to connect with the ATM switching equipment 1 in order from the terminal 7 →
It is assumed that the call is connected by the route of the ATM switching device 2 → the ATM switching device 3 → the ATM switching device 4. The ATM switching devices 2 to 6 have the same configuration and operation as the ATM switching device 1 shown in FIG.

FIGS. 3 to 6 show an AT according to an embodiment of the present invention.
It is a block diagram which shows the flow of a processing operation of an M switching network. The processing operation of the ATM switching network according to one embodiment of the present invention will be described with reference to FIGS.

First, a sequence until an important call is established in the ATM switching network according to one embodiment of the present invention will be described with reference to FIG.

The terminal 7 operates the path for connecting to the server 8 as an important call. For this connection, the terminal 7 transmits an important call setting request 20. ATM switching equipment 1-4
Receives the important call setting request 20, the important call setting request 2
0 is sequentially transferred and recognized as an important call.
Finally, upon receiving the important call setting request 20, the server 8 accepts the important call setting request 20, and returns an important call setting response 21.

Each of the ATM switching devices 4 to 1 sequentially returns the important call setting request 21 and statically sets the important call path 30 in the same device as the PVC which is a fixed connection. At this time, each of the ATM switching devices 4 to 1 saves the information of the static path similar to the PVC, as well as the destination terminal address and the call direction information.

At this point, each of the ATM switching devices 4 to 1 performs OAM hardware monitoring setting for the line on which the path is established. For example, in the ATM switching device 1, a path connection is made between the logical port 40 and the logical port 41, and OAM hardware monitoring is performed on the logical port 40 and the logical port 41. Further, since each of the ATM switching devices 4 to 1 performs the OAM failure monitoring, the ATM switching devices 4 to 1 do not perform the polling path monitoring by the soft protocol which is the normal SVC path monitoring control method.

After that, the conventional SVC system is used, as shown in FIG.
The communication between the terminals 7 and 9 is started, and if any failure occurs in the ATM switching device 2 during the call setting, the ATM switching device 1 sets a detour. To avoid disconnecting the call.

The sequence up to the setting of the detour due to the occurrence of the fault will be described with reference to FIG.

The ATM switching device 2 sends an AOM failure notification CEL 50, which is a failure notification by an OAM cell, to the ATM switching device 1 and the ATM switching device 3 when a failure occurs in its own device. Alternatively, when the ATM switching device 2 goes down, the ATM switching device 1 and the ATM switching device 3 detect a line failure.

At this time, since it may be recovered immediately, the temporary port failure timer is set in the ATM switching device 1 which is the preceding stage of the failure station due to the failure of the destination port, and the situation is observed. If the communication is restored during that time, the temporary failure timer is canceled, and communication is performed using the same route as before. However, when it is determined that the temporary failure timer has timed out and the temporary failure timer does not recover immediately, the detour setting request 61 for the destination terminal address stored in the ATM switching device 1 is stored.
Send

The detour setting request 61 is transmitted to the ATM switching device 5
→ Since the data is transferred to the ATM switching device 4 via the ATM switching device 6, the ATM switching device 4 returns a detour setting response 62. At this time, the ATM switching device 4 switches the original important call path to the bypass path 71. The detour setting response 62 is sequentially transmitted from the ATM switching device 6 to the A
The data is transferred to the TM exchange 1, and each ATM exchange 6,
A detour path 71 is set in 5,1.

In the ATM switching device 1, the previous important call path is switched to the bypass path 71. However, since the detour path 71 is a temporary path, failure monitoring is performed by the conventional SVC method.

Further, in the ATM switching device 1, since the ATM switching device 2 may have a fixed fault, a fixed fault timer is set and the state is checked. At this time, the previous important path is not cut off by the ATM switching device 3 or later that recognizes the path failure on the calling side. A before the fixed fault timer times out
When the TM switching device 2 recovers, the ATM switching device 1
Disconnects the bypass path 71 and switches to the original path connection.

Next, a sequence from when the ATM switching device 2 is restored and the detour is cut to when the original important call path is set will be described with reference to FIG.

When the ATM switching device 2 recovers, the OAM
A failure recovery notification CEL 90 is transmitted to the ATM switching devices 1 and 3. At this time, when the destination port detects a line failure recovery in the ATM switching device 1 preceding the failed station due to a failure, the fixed failure timer is released.

The ATM switching apparatus 1 sends a detour release request 81 to a detour path set to disconnect the detour.
Send This detour release request 81 is transmitted to the ATM switching device 5
→ Since the data is transferred to the ATM switching device 4 via the ATM switching device 6, the ATM switching device 4 returns a detour release response 82. At this time, the ATM switching device 4 switches the bypass path to the original important call path. The detour release responses 82 are sequentially
ATM switch 6 → ATM via ATM switch 5
Since the data is transferred to the switching device 1, each ATM switching device 6,
In 5,1, the bypass path is disconnected. Further, in the ATM switching device 1, by switching the original bypass path 71 to the original important call path, the communication with the original important call path connection is restored.

When the fixed failure timer times out, the currently established detour is switched to the main path as an important call, and the previous old important call is disconnected.

Referring to FIG. 6, a sequence until the above-described ATM switching device 2 becomes a fixed fault and the detour is switched to the present route path will be described.

When the fixed failure timer times out, the ATM switching device 1 causes the ATM switching device 2 having a fixed failure to perform the operation.
An important call disconnection notification 111 is transmitted to the user. Also, ATM
The switching device 1 transmits an important call change request 101 for a path route established as a detour. The important call change request 101 is transferred to the ATM switching device 4 via the ATM switching device 5 → ATM switching device 6.

At this time, each of the ATM switching devices 5, 6, and 4, which has received the important call change request 101, uses the detour up to now as a new main path and uses the new path management method from the conventional SVC path management method. Switch to management. In order to disconnect the old important call path, the ATM switching apparatus 4 has a fixed failure according to the path of the old important call.
An important call disconnection request 111 is transmitted to the user. Upon receiving the important call disconnection request 111, the ATM switching devices 3 and 2 delete the old important call path.

Thus, the terminal 7 → the ATM switching device 1
The path route from the ATM switching device 5 to the ATM switching device 6 to the ATM switching device 4 to the server 8 is changed to a new important call path route.

At this time, it is conceivable that the ATM switching apparatus 2 cannot recognize the reception of the important call disconnection request 111 due to the system down or the like. When you recover from, compare the current time with the saved time,
Delete the old connection path when the fixed failure time is exceeded.

Also, in the ATM switching apparatus 1, the setting of the alternate call cannot be made until the setting of the alternate path reaches the timeout of the fixed failure timer, the case where the call disconnection instruction is received from the terminal 7 or the server 8, or The important call path currently established when the terminal 7 or server 8 fails
Disconnect between ND and END.

As described above, the important path is deleted between the END and the END between the terminal 7 and the server 8 when the terminal 7 or the server 8 fails, when a disconnection instruction is received, or when a fixed failure occurs. Only when the detour setting is not possible.

In the above configuration, messages relating to important calls and alternate calls are newly provided. However, since the call setting between stations and the call disconnection processing sequence are not different from the conventional method, new messages are added to the existing messages. May be added as an information element.

In the above configuration, the terminals 7 and 9 must also transmit a general call and an important call. However, in consideration of using an existing terminal, the ATM switching equipment 1
The terminal may be treated as an important call in (1) to (6) as data, and the incoming call to the terminal and the call from the terminal may have a network configuration in which an important call is set at the calling station.

Further, when a call is disconnected spontaneously for recovery from a fixed failure or the like, a protocol sequence for inquiring an adjacent station whether the call may be disconnected may be added.

In this way, a call to the server 8 which is always connected can be set to a higher priority than a communication call to which it is temporarily connected. And the path management method is OAM
, Which is not affected by the load of communication calls, and because this setting method reduces the load on the ATM switching devices 1 to 6 itself, the network load can be reduced even when the number of terminals is large. .

Further, the connected important call is statically handled after the call is set up, and data communication can be performed without disconnecting the call even after restarting the relay station or recovering from the primary failure of the relay line. Regarding time failures, it is possible to reconnect the detour route without disconnecting the call originating and terminating terminal only by detour reconnection in the network. Can be stabilized.

[0093]

As described above, according to the present invention, in an ATM switching network in which data communication between a terminal and a server is performed in an asynchronous transfer mode via a plurality of switching devices, at least a connection is always made to the server. After establishing a call for an important path that must be established, call setup information is used as important call path information as a fixed connection PVC (Permane).
nt Virtual Circuit), a plurality of switching devices are provided with the same configuration for static management, and by making it difficult for calls to be disconnected between END terminals in the event of a network failure, the bypass method is changed to change the bypass method between the END terminals. There is an effect that disconnection of an important call can be suppressed as much as possible and a stable network system can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM switching device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a system configuration of an ATM switching network according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a flow of a processing operation of the ATM switching network according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a flow of a processing operation of the ATM switching network according to one embodiment of the present invention.

FIG. 5 is a block diagram showing a processing operation flow of the ATM switching network according to one embodiment of the present invention.

FIG. 6 is a block diagram showing a processing operation flow of the ATM switching network according to one embodiment of the present invention.

[Explanation of symbols]

 1-6 ATM switching device 7,9 terminal 8 server 11 switching control processing unit 12 control path gateway device 13 switch control device 14 line control device 15 clock device 111 fault management processing unit 112 SVC control processing unit 113 PVC control processing unit 114 system Down time detection processing unit 115 Important call path control processing unit 141 Line communication control unit 142 Buffer control unit 143 OAM control unit 144 OAM CELL monitoring and extraction unit 145 Line failure detection unit 1121 MSG call control unit 1122 Routing control unit 1131 PVC setting processing unit 1132 PVC path deletion processing unit

Claims (3)

[Claims] An important call control method in an ATM switching network in which data communication between a terminal and a server is performed in an asynchronous transfer mode via a plurality of switching devices, unless at least the server is always connected to the server. After the call is established, the call setting information is set as important call path information after the call is established, and the permanent connection is a permanent connection (PVC).
An important call control method characterized in that each of the plurality of switching devices is provided with a configuration for static management similar to that of a dual circuit, so that a call is not easily disconnected between END terminals in the event of a network failure. 2. The important call control method according to claim 1, wherein the important path is a path that affects another path when the approximate path is disconnected. 3. The switching system according to claim 1, wherein each of the plurality of switching devices is configured to detect an occurrence of a failure by ending the primary failure based on the failure duration.
Set a temporary detour without disconnecting the call between terminals,
3. The important call control system according to claim 1, wherein the route is changed to the original call immediately upon restoration.