JP3349988B2 - Method and system for automatically switching back from detour route in ATM network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asynchronous transfer mode (ATM: Asynchronous Transfer).
The present invention relates to a method and system for automatically switching back from a detour route in a network using an r Mode (r Mode) method, and in particular, to a PNNI (Private Network).
The present invention relates to a method and system for automatically switching back from a detour route in a PNNI network suitable for -to-Network Interface (Routing).

[0002]

2. Description of the Related Art A conventional PNNI (Private Ne) is used.
work-to-networkInterfac
e) The routing method is based on the ATM Forum Recommendation af-
pnni-0055.000 (The ATM For
um Technical Committee, "P
ribate Network-Network In
terface Specification Ver
session1.0 (PNNI 1.0) ", af-pnn
i-0055.000, March, 1996).

[0003] In a network using the ATM system, high quality is required such that a service interruption situation does not occur as much as possible like a virtual leased line service. In this case, it is necessary to prevent the transfer data from being damaged when the routing paths are switched in the plurality of ATM switches (nodes).

For example, in the network shown in FIG. 1, it is assumed that a line failure has occurred in the optimum route 6 between the originating and terminating ATM switches 3 and 4, and there is a call in communication on the detour route 7. After that, the line failure of the optimal route 6 is recovered,
Conventionally, when switching back from the detour route 7 to the optimum route 6, it is necessary for the user to cut off the detour route 7 once and to set up the call again for the optimum route 6.

[0005] One of the problems here is that when a line failure occurs on a line in use by a user who wants to communicate on a line with high data transfer efficiency without interruption, call rerouting occurs. , The line selected for detour is long distance,
Data transfer efficiency decreases due to an increase in the number of relay stages of the ATM switch, etc., and even after recovery from a line failure, it is not possible to switch back to the line of the optimal route, and communication must be continued on a line with low data transfer efficiency. There is a point that does not become. The reason is that, in the conventional method, a call that has been bypassed due to the occurrence of a line failure cannot be automatically switched back to the line that was communicating before the detour when the line failure was recovered, without being reconnected. That's why.

A technique disclosed in Japanese Patent Application Laid-Open No. 7-221791 is known as a detour system of a frame relay relay path. In a communication network having no retransmission procedure, a line for checking the line quality based on the ratio of error frames to all frames received within a certain time and notifying the check result in response to an inquiry from the detour processing means Quality check means, and inquires the line quality check means of the line quality at predetermined time intervals, and switches to a bypass route when the line quality is "abnormal". It is provided with detour processing means and switchback means for returning the detour to the original line.

[0007] Regarding a detour route setting and switching control method in an ATM network using a VPC, see Japanese Patent Laid-Open No.
A technique disclosed in Japanese Patent Application No. 219705 is known. The ATM node has a cell handler and a message assembly /
Cellular device and VC for setting and releasing VCC band and route
C control device, VCC route control device for setting only the VCC route, address / VP correspondence table, header conversion device, switchback execution device, bypass route selection VCC registration buffer, and V
It comprises a P resource management table and a VP band resource management device.

With respect to a connection setting and recovery method in an ATM network, a technique disclosed in Japanese Patent Application Laid-Open No. 10-135980 is known. Topology change, connection setting failure, line disconnection, line quality degradation, update the contents when receiving information, topology table to hold and calculate the route information when receiving such information,
It has a path candidate table to hold, and after the update processing of the topology table and the path candidate table is completed or after receiving a new connection setup message, the connection setting is performed using the topology table and the path candidate table.

Regarding a method of providing an ATM best effort service using a spare band, see Japanese Patent Laid-Open No. 10-2762.
The technology disclosed in Japanese Patent Application Publication No. 04-2004 is known. High reliability V
P.VC is accommodated in the second path without duplication in the first path and the second path between the opposing devices. If there is no failure in the first path and the second path, the reliable VP / VC selects the first path. If a failure occurs in the first path, the reliable VP / VC detects the failure and automatically
Switch to the route. When the failure of the first path is recovered, the reliable VP / VC is switched back from the second path to the first path.

With respect to a path switching method in an ATM network, a technique disclosed in Japanese Patent Application Laid-Open No. 10-303913 is known. A fixed logical path for management by PVC is previously set in a mesh form between each ATM switch on the ATM network, and the normality of each path is monitored by a loopback test. And the communication can be continued. In addition, by returning to the working route upon recovery from the failure, communication efficiency is improved.

Regarding the method of recovering from the failure of the ATM exchange,
A technique disclosed in Japanese Patent Application Laid-Open No. H11-27286 is known. A normal route PVC is set between the input line of the working line and the output line of the working line, and a PVC of a bypass route is set between the input line of the working line and the output line of the protection line.
Is set, and when a line failure of the output line is detected, autonomous switching from the PVC of the normal route to the PVC of the bypass route is performed, and cells are transmitted using the output line of the protection line. .

Regarding the ATM communication network, Japanese Patent Laid-Open No. 11-2
There is known a technique disclosed in Japanese Patent No. 7325. LA
N are connected to the center network in a star shape. This center network is an optical wavelength routing network in which a transfer route is fixedly set for each wavelength. When a destination cell other than the own LAN arrives, the cell is transferred to a route other than the route from which the cell arrives. Thereby, this cell can finally reach the LAN of the desired destination. By periodically transmitting and receiving OAM cells, a failure in the transmission path can be detected and recovered.

[0013] As a batch switching method at the time of bypassing a route-designated PVC, a technique disclosed in Japanese Patent Application Laid-Open No. H11-74895 is known. Route the designated PVC to the first, third and fifth nodes (PVC1) and the first, third, fifth and sixth
When a failure occurs in the third node, which is set in the node (PVC2), each of the PVCs includes the first, second, fourth, sixth, and
It detours to the fifth node and the first, second, fourth, and sixth nodes, and the PVC status of the NMS and the node becomes “detouring”.
The node monitors periodically, and the third node recovers and the PV
When the designated route of C becomes available, a batch switchback of PVC is executed. Alternatively, the PVC is switched back to the designated route when the maintenance person inputs a command from the NMS. When the switchback is completed normally, the PVC status of the NMS and the node becomes “route designation”.

[0014]

It is desirable that a call that is communicating on the alternate route due to the line failure of the optimum route recovers from the alternate route to the optimum route when the line failure of the optimum route is recovered. .

[0015]

Means for solving the problem are indicated in the following description in which the means for solving the problem are expressed according to the claims. It shows that it corresponds to the member, the process, and the operation of at least one of a plurality of forms of the present invention. However, the solution means of the present invention is to be interpreted as being limited to the members of the embodiment indicated by those numerals. It is not a thing, but to clarify the correspondence.

According to the method of automatically switching back from a detour route in an ATM network according to the present invention, a call that is detouring from a first route (6) in which a line failure has occurred and communicating on a second route (7) is transferred to the first route. (6) A method of automatically switching back to the first route (6) upon recovery from a line failure, comprising: (a) providing first and second ATM switches (3, 5); ) Providing said first route (6) as an optimal route between said first and second ATM switches (3, 5); and (c) providing said first and second ATM switches (3, 5). (D) providing the second route (7) as a detour route of the first route (6); and (d) providing the second route (7) between the first and second ATM switches (3, 5). The first route during communication (25) during the second route (7) A step (27) line failure in 6) for detecting that the recovered (26), (e)
When the line recovery of the first route (6) is detected in the step (d), a call setup on the first route (6) between the first and second ATM switches (3, 5). And (f) buffering the transmission data from the first ATM switch (3) to the second route (7) in the first ATM switch (3) and performing the second ATM The transmission data from the switch (5) to the second route (7) is buffered in the second ATM switch (5), and the data is transmitted to the second route (7).
(G) disconnecting the second route (7) after the (f) step; and (h) disconnecting the first and second ATM switches (3,
5) communicating the transmission data buffered in 5) through the first route (6) in which the call setting has been performed.

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the ATM network includes a PNN.
I (Private Network-to-Network)
Ork Interface).

According to the method for automatically switching back from a detour route in an ATM network according to the present invention, a call which is detouring from a first route (6) in which a line failure has occurred and communicating on a second route (7) is transferred to the first route. (6) A method of automatically switching back to the first route (6) upon recovery from a line failure, comprising: (a) providing first and second ATM switches (3, 5); ) Providing said first route (6) as an optimal route between said first and second ATM switches (3, 5); and (c) providing said first and second ATM switches (3, 5). And (i) providing the second route (7) as a detour route of the first route (6); and (i) providing the second route (7) with the second ATM switch (5). ) (2)
(5) generating a call setup message signal in the first ATM switch (3) upon detecting (26) that the line failure of the first route (6) has been restored in (5); j) transmitting the generated call setup message signal to the second ATM via the first route (6);
Transmitting to the second ATM switch the data transmitted from the second ATM switch to the second route in response to the call setup message signal; Stopping the transmission to the second route (7) by buffering in the switch (5) (2)
8) and (l) the transmission data from the first ATM switch (3) to the second route (7) is transmitted to the first ATM switch (3).
(M) buffering at the switch (3) and stopping transmission to the second route (7);
After the call setup corresponding to the call setup message signal transmitted in step (j) is completed, the first AT
Generating a disconnection message signal for disconnecting said second route (7) in the M switch (3);
(N) transmitting the generated disconnection message signal to the second ATM switch (5); (o) generating a disconnection response message signal in response to the disconnection message signal; Signal to the first
Transmitting to the ATM switch (3) of (a).
Disconnecting the second route (7) in response to the disconnection response message signal; and (q) transmitting the buffered transmission data in the step (l) in response to the disconnection response message signal. Transmitting the buffered transmission data in the step (k) in response to the transmission data transmitted in the step (31) and (r) in the step (q); Transmitting to the route (6) (32).

In the method for automatically switching back from a detour route in an ATM network according to the present invention, (s) communication is performed between the first and second ATM switches (5) via the second route (7). A call setting message signal including a switchback target ID (33) indicating a call to be switched back to the first route (6) when the line failure of the first route (6) is recovered from the call is transmitted to the And outputting the call from the first ATM switch (3) to the second ATM switch (5). In the step (e), the call setting is performed for the call to be switched back.

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the call setting message signal including the switching target ID (33) in the step (s) is transmitted to the first ATM switch (3). ) Generated at the first terminal (1) at the preceding stage, and the generated switchback target I
D (33) is transmitted to the first
Of the ATM switch (3) and outputs it to the second ATM switch (5).

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the call setting message signal including the switching target ID (33) in the step (s) is transmitted to the first ATM switch (3). ), The first ATM switch (3) inputs the call setup message signal generated by the first terminal (1) at the preceding stage, and the switchback target ID (33) is added to the input call setup message signal. Set.

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the step (d) comprises:
Based on the PNNI topology information, it is detected that the line failure of the first route (6) has been recovered.

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the first and second A
The buffering of the transmission data from each of the TM switches (3, 5) to the second route (7) is performed by completing the call setup for the first route (6) where the line failure has been recovered. The operation is performed until switching back from the second route (7) to the first route (6) is completed, and the second route (7) is performed.
The return from the first route (6) to the first route (6) is performed upon the disconnection of the second route (7).

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the step (e) comprises:
The communication is performed during the communication on the second route (7) between the first and second ATM switches (3, 5).

In the method for automatically switching back from a detour route in an ATM network according to the present invention, when the call setup is completed in the step (e), each of the first and second ATM switches (3, 5) is used. In the routing table, the port value to the terminal side, VPI (Virt
ual Path Identification (Virtual Path Identifier) value and VCI (Virtual
Connection Identificatio
n: the value of the network-side port to the first route (6) without setting the value
(H) in the routing table of each of the first and second ATM switches (3, 5) in the first route (6) set in the step (e). ) To the network side port value,
The communication route is changed by replacing the VPI value and the VCI value instead of the network side port value, the VPI value and the VCI value to the second route (7) corresponding to the communication on the second route (7). Switching from the second route (7) to the first route (6).

In the method for automatically switching back from a detour route in an ATM network according to the present invention, the step (f) comprises:
Buffering the transmission data in an output buffer (11) for the second route (7) in each of the first and second ATM switches (3, 5); And in each of the second ATM switches (3, 5), the transmission data buffered in the output buffer (11) for the second route (7) is output to the output buffer for the first route (6). The data is copied to (12), and communication is performed through the first route (6).

The system for automatically reverting from a detour route in an ATM network according to the present invention is a system for detouring from a first route (6) where a line failure has occurred and communicating a call on a second route (7). (6) A system for automatically switching back to the first route (6) at the time of recovery from a line failure, comprising: a first ATM switch (3);
Between the switch (3) and the first route as an optimal route.
A second ATM switch (5) connecting each of a route (6) and a second route (7) as a detour route of the first route (6);
When the line failure of the first route (6) is recovered during communication on the second route (7), the M switch (3)
Without disconnecting the communication on the second route (7), a call setup message signal is generated and output to the second ATM switch (5) via the first route (6); Buffer the transmission data to route (7),
When the line of the first route (6) is connected, the buffered transmission data is output to the first route (6), and the second ATM switch (5)
In response to the call setup message signal, transmission data to the second route (7) is buffered, and when the line of the first route (6) is connected, the buffered transmission data is Output to the first route (6).

In the system for automatically switching back from a detour route in an ATM network according to the present invention, the first ATM switch (3) is configured to switch the first route (6) of the calls communicated on the second route (7). ), A call-back target ID (33) indicating that the call is to be returned to the first route (6) at the time of recovery from the line failure is set in the generated call setup message signal, and the first and second calls are set. The ATM switch (3, 5) of the first embodiment switches a call corresponding to the switching target ID (33) when the line of the first route (6) is connected.
Return to the first route (6).

In the system for automatically switching back from a detour route in an ATM network according to the present invention,
When the line of the first route (6) is connected, each of the ATM switches (3, 5) of the first and second ATM switches (3, 5) Port value to terminal side, VPI (V
actual Path Identificatio
n: virtual path identifier) value and VCI (Virt)
ual Connection Identifica
tion: virtual connection identifier) without setting the value, the network-side port value to the first route (6),
When setting the VPI value and the VCI value and outputting the buffered transmission data to the second route (7) to the first route (6), the first and second ATM switches (3 In each of the routing tables 5) and 5), the network-side port value, VPI value and VCI value for the set first route (6) are
The network side port value, the VPI value, and the VCI value for the second route (7) corresponding to the communication on the second route (7) are replaced with each other.

In the system for automatically switching back from a detour route in an ATM network according to the present invention,
Each of the ATM switches (3, 5) buffers the transmission data in the output buffer (11) for the second route (7) and transmits the buffered transmission data to the second route (7). When outputting data to the first route (6), the transmission data buffered in the output buffer (11) to the second route (7) is output to the output buffer to the first route (6). (1
Copy to 2).

According to the present invention, a call being routed due to a line failure can be
An object of the present invention is to provide a configuration for automatically switching back to an optimum route without disconnecting a call upon recovery from a line failure. In FIG. 1, when a call that is communicating on the optimum route (6) is disconnected due to a line failure and call setting is performed on a bypass route (7) for call detour, call setting information and call setting are used. Save the used routing list. When the recovery of the line failure is detected from the change in the PNNI topology information, the line weights of the detour route (7) and the optimal route (6) from which the line failure has been recovered are compared (the weight of the line of the detour route (7) is (Calculation is performed based on the routing list saved at the time of call setting), and when it is determined that the optimum route (6) for which the line failure has been recovered is optimal, call setting is performed for the optimum route (6) for which the line failure has been recovered, and the line failure has been recovered. By switching between the optimal route (6) and the detour route (7), it is possible to switch back to the line before detour.

According to the present invention, a call setup message (33) indicating a call-back target ID (33) indicating that a call being routed back from a call originating terminal (1) due to a line failure is to be switched back together with the recovery of the line failure. When call setup is performed according to FIG.
The call setting message (FIG. 7) including the switchback target ID (33) is transferred from the originating ATM switch (3) to the destination ATM switch (5).

In the present invention, when the optimum route (6) is selected for the call to be switched back, triggered by a change in the state of the PNNI topology information due to the line failure recovery (26), the originating ATM switch ( In 3), a call setup message (FIG. 7) is created (27), and recall setup is performed for the optimum route (6) from which the line failure has been recovered.

When the call setting for the optimum route (6) from which the line failure has been recovered is completed by the recall setting described above, until the return from the detour route (7) to the optimum route (6) is completed. The transmission data from the terminals (1, 2) to the detour route (7) is buffered.

Switching back from the detour route (7) to the line (6) in which the line failure has been recovered is performed upon disconnection of the detour route (7). Port / VPI / VC to detour route
This is performed by exchanging the I value and the port / VPI / VCI value to the optimal route (6) from which the line failure has been recovered, and the contents of the output buffer (11) to the detour route (7) on the hardware. Is copied to the output buffer (12) for the route (6) where the line failure has been recovered (30).

An automatic fail-back switching system in a PNNI network according to the present invention comprises a calling terminal (1) for transmitting a call setup message and data, and a calling ATM switch (3) for receiving the call setup message and data.
The destination ATM switch (5) connected to the source ATM switch (3) by the optimal route (6);
An ATM switch (4) connected by a detour route (7) between the TM switch (3) and the destination ATM switch (5);
The calling terminal (1) via the destination ATM switch (5)
And a destination terminal (2) for receiving a call setup message and data from the terminal. The source ATM switch (3) performs a call setup from the source terminal (1) to the destination terminal (2). The switching target ID (33) is assigned to the call setting message, the optimum route (6) is calculated based on the PNNI topology information, and the switching target ID is assigned to the destination ATM switch (5). Send a call setup message.

[0037] In the automatic fail-back switching system in the PNNI network according to the present invention, when the originating ATM switch (3) receives the call setting acceptance message returned from the terminating ATM switch (5), the switching is performed. The call setting information including the target ID (33) is stored, and
The TM switch (5) transmits the call setting message to the destination terminal (2), and when the call setting acceptance message is returned from the destination terminal (2), the return target ID (33). Is stored, and further upon receiving a connection message from the called terminal (2),
By returning the connection message including the routing list included in the call setting information to the source ATM switch (3), the setting of the ATM path by the optimal route (6) is completed, and the source terminal (1) Communication between the terminal and the destination terminal (2) is started.

[0038] In the automatic failback system for failure detour in the PNNI network of the present invention, when a line failure occurs in the optimum route (6), the originating ATM switch (3) transmits the PNNI from the originating terminal (1). When a call setup message for the detour route (7) based on the topology information is received, the switchback target ID (3
By exchanging the call setup message with 3) with the ATM switch (4) connected by the bypass route (7), the originating terminal (1) and the destination terminal (1) by the bypass route (7) are exchanged. 2), and when the line failure in the optimum route (6) is recovered, call setting is performed again on the optimum route (6) in accordance with a change in the PNNI topology information. .

In the automatic fail-back switching system in the PNNI network according to the present invention, the originating ATM switch (3) determines the weight of the optimal route (6) for which the line has been recovered from the failure and the weight of the line of the bypass route (7). If it is determined that the optimum route (6) is appropriate by comparing the two, the optimum route (6) is selected.

According to the method for automatically switching back to a fault bypass in a PNNI network according to the present invention, a first step of transmitting a call setup message and data from a calling terminal (1) and an ATM switch (3) for sending the call setup message and data are performed. ) And the originating AT
A third step of connecting the destination ATM switch (5) to the M switch (3) by an optimal route (6), and an ATM between the source ATM switch (3) and the destination ATM switch (5).
A fourth step of connecting a switch (4) by a detour route (7), and a call setting message and data from the calling terminal (1) are received by the called terminal (2) via the called ATM switch (5). Fifth step and the originating AT
A sixth step of, when an M switch (3) sets up a call from the calling terminal (1) to the called terminal (2), assigning a switchback target ID to the call setting message; A seventh step of calculating an optimum route (6) by the switch (3) based on PNNI topology information and transmitting a call setup message to which the switchback target ID is assigned to the destination ATM switch (5); It has.

[0041] In the automatic failback method for failure detour in the PNNI network of the present invention, in the sixth step, upon receiving the call setting acceptance message returned from the destination ATM switch (5), An eighth step of storing call setup information including an ID, and a ninth step of transmitting the call setup message to the destination terminal (2).
And a tenth step of storing call setting information including the switchback target ID when the call setting acceptance message is returned from the destination terminal (2). The seventh step includes Receiving an access message from the destination terminal (2), returning an access message including a routing list included in the call setting information to the originating ATM switch (3); A twelfth step of setting up an ATM path according to 6).

[0042] In the method of automatically switching back to a fault detour in a PNNI network according to the present invention, the seventh step or the twelfth step includes the steps of: when a line fault occurs in the optimum route (6); P from)
The detour route based on NNI topology information (7)
A thirteenth step of accepting a call setup message to the ATM switch, and a fourteenth step of exchanging the call setup message with the switchback target ID with the ATM switch connected by the bypass route (7). A fifteenth step of starting communication between the calling terminal (1) and the called terminal (2) by the detour route (7), and when the line failure in the optimum route (6) is recovered, the PNNI
A sixteenth step of re-establishing a call with respect to the optimal route (6) according to the change in the topology information is included.

In the method of automatically switching back to a fault bypass in a PNNI network according to the present invention, the twelfth step or the sixteenth step includes selecting the optimum route (6) for which the line has recovered from the fault and the bypass route (7). The method includes a seventeenth step of calculating the weight of the line and an eighteenth step of selecting the optimum route (6) when it is determined that the optimum route (6) is appropriate by comparing the two.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of an automatic failback system for failure detour in the PNNI network of the present embodiment (hereinafter, simply referred to as an automatic failback system). FIG. 2 is a diagram illustrating a hardware configuration inside the ATM switch according to the present embodiment. 3 to 5
FIG. 5 is a sequence diagram for explaining the operation of the automatic failback system of the present embodiment. FIG. 6 is a diagram showing a switchback target ID information element set in the call setup message by the automatic switchback system of the present embodiment. FIG. 7 is a diagram showing the contents of a call setup message used in the automatic failback system of the present embodiment. FIG. 8 is a diagram showing the contents of the connection message used in the automatic failback system of the present embodiment. FIG. 9 is a diagram showing call setting information stored in the calling ATM switch according to the present embodiment. FIG. 10 is a diagram showing call setting information stored in the destination ATM switch according to the present embodiment. FIG. 11 is a diagram showing an image of one routing table in the source ATM switch and the destination ATM switch according to the present embodiment. FIG. 12 shows the originating AT of the present embodiment.
It is a figure showing the image of other routing tables in an M switch and a destination ATM switch. FIG.
It is a figure which shows the image of further another routing table in the originating ATM switch and destination ATM switch of this embodiment.

As shown in FIG. 1, this embodiment comprises a calling terminal 1, a called terminal 2, a calling ATM switch 3, an ATM switch 4, and a called ATM switch 5. Also,
An optimal route 6 connecting the originating ATM switch 3 and the destination ATM switch 5 and a detour route 7 connecting the originating ATM switch 3 to the destination ATM switch 5 via the ATM switch 4 are included.

As shown in FIG. 2, the hardware configuration of each of the source ATM switch 3, the ATM switch 4, and the destination ATM switch 5 according to this embodiment includes a switch unit 8, an input buffer unit 9, and an output buffer unit. Unit 10. Further, the output buffer 11 to the detour route 7 inside the output buffer unit 10 and the output buffer unit 10
And an output buffer 12 to the optimum route 6 inside.

Next, the operation of the automatic switchback system having such a configuration will be described. In the configuration of FIG.
Since NI is a known technology defined in the above-mentioned ATM forum, detailed description thereof is omitted.

First, the normal operation (reference numerals 13 to 18) will be described with reference to FIGS. 3 to 5, and then the switching operation to the bypass route 7 (19 to 25) when a line failure occurs in the optimum route 6 will be described. The operation (26 to 32) of switching back from the detour route 7 to the optimal route 6 when the line failure of the optimal route 6 is finally recovered will be described.

First, the normal operation will be described. When a call is set up from the calling terminal 1 to the called terminal 2, a known technique uses a call setting message that does not include a switchback target ID indicated by reference numeral 33 in FIG. 7. In the present embodiment, the call setting message is used. Is given a new switchback target ID 33 shown in FIG. 6 and set as shown in FIG. 7 (13 in FIG. 3).

Here, the return target ID 33 is the originating ATM.
This is a value that is uniquely set by the user to be used for identification when a plurality of calls multiplexed at the same incoming / outgoing ATM address are to be switched back and used by taking over from the switch 3 to the destination ATM switch 5. .

FIG. 6 shows information elements of the switching target ID 33 set in the call setup message, and includes an information element descriptor, an extension, a standard coding, and an IE indication field.

As shown in FIG. 7, the call setting message includes the following in addition to the switching target ID 33. That is, the protocol identifier, call number, message type, message length, AAL (ATM Adapta)
ion Layer: ATM adaptation layer) parameter, ABR additional parameter, ABR setting parameter, alternative ATM traffic descriptor, ATM traffic descriptor, broadband transmission capability, broadband higher layer information,
Broadband repetition identifier, wideband lower layer information, called number, called party software PVP (Permanent V)
(virtual path: fixed connection type virtual path) C / P
VC (Permanent Virtual Channel)
el: fixed connection type virtual channel) C, destination sub address,
Calling number, calling party software PVPC / PVCC, calling subaddress, connection identifier, connection selection range, routing list, endpoint reference, end-to-end relay delay, extended QoS (Quality)
of Service (quality of service) parameters, general identifier transfer, minimum allowable ATM traffic descriptor, notification indicator, QoS parameters, and relay network selection.

In the calling ATM switch 3 that has received the call setting message from the calling terminal 1, the A held in the PNNI
The optimum route 6 is calculated based on “PNNI topology information” for managing the state of the TM switch, the line, and the like, and a call setting message is transmitted to the destination ATM switch 5 based on the calculation result.

In the calling ATM switch 3 to which the call setting acceptance message is returned from the destination ATM switch 5, only the call setting message is stored in the known technique, but in the present embodiment, the call setting message including the switching target ID 33 and Network Port / Network VPI (Virtual Path I)
(denification: virtual path identifier)
/ Network-side VCI (Virtual Connection)
The identification (virtual connection identifier) value is stored in the structure shown in FIG. 9 (FIG. 3).
14). At the stage shown in FIG. 3 (14 in FIG. 3),
The routing list described in FIG. 9 is not saved.

FIG. 9 shows call setting information stored in the calling ATM switch 3, which includes the above-described network side port, network side VPI, and network side VCI.

The destination ATM switch 5 that has received the call setting message from the source ATM switch 3 transmits the call setting message to the destination terminal 2. The destination ATM switch 5 to which the call setting acceptance message is returned from the destination terminal 2 is not specified in the known technology, but in the present embodiment, the destination ATM switch 5
M address, return target ID, network side port / VPI / V
The CI value is stored in the structure shown in FIG. Also, AT
The M switch 5 stores a "routing list" indicating the call setting route from the originating ATM switch 3 to the destination ATM switch 5, which is set in the call setting message as shown in FIG. 7 (15 in FIG. 3). .

The destination ATM switch 5 that has received the connection message from the destination terminal 2 only returns the connection message to the originating ATM switch 3 according to the known technique, but in the present embodiment, the routing specification stored in (15 in FIG. 3). The list is copied to the connection message as indicated by reference numeral 34 in FIG. 8 and returned to the source ATM switch 3 (16 in FIG. 3).

FIG. 8 shows the contents of the connection message. In addition to the copied routing list 34,
Includes: Protocol identifier, call number,
Message type, message length, ABR additional parameter, ABR setting parameter, AAL parameter, ATM
Traffic descriptor, broadband lower layer information, destination party software PVPC / PVCC, binding number, binding subaddress, endpoint reference, end-to-end relay delay, extended QoS parameters, general identifier transfer, and notification indicator.

In the source ATM switch 3 that has received the connection message from the destination ATM switch 5, although it is not particularly defined in the known art, in the present embodiment, the routing list 34 set in the connection message is described in FIG. 14)
Is stored in the structure shown in FIG. 7 together with the information stored in step (17 in FIG. 3).

The originating terminal 1 receives the connection message from the originating ATM switch 3, and the setting of the ATM path by the optimum route 6 is completed. Communication between the calling terminal 1 and the receiving terminal 2 is started (18 in FIG. 3).

Next, the operation of switching to the detour route 7 when a line failure occurs in the optimum route 6 will be described.

First, a line fault occurs in the optimum route 6 during communication through the optimum route 6, and the line is disconnected. The information saved in (14 in FIG. 3), (15 in FIG. 3) and (17 in FIG. 3) due to the line disconnection is
All are erased (19 in FIG. 3).

When the line is disconnected, the originating terminal 1 sets up a call again to the destination terminal 2 based on the PNNI topology information for the detour route 7 (because the optimal route 6 has a line failure).

Procedure at that time (20 in FIG. 4 to 24 in FIG. 4)
Is the same as the procedure from (13 in FIG. 3 to 17 in FIG. 3). The calling terminal 1 receives the connection message from the calling ATM switch 3, and the setting of the ATM path by the detour route 7 is completed. Communication between the calling terminal 1 and the receiving terminal 2 is started (25 in FIG. 4).

When the call setting for the detour route 7 is completed, the originating ATM switch 3 and the destination AT
As shown in FIG. 11, the port / VPI / VCI values on the terminal side and the network side are set in the routing table of the M switch 5. According to this routing table, the source ATM switch 3 and the destination ATM switch 5 select a port and rewrite a VC (virtual connection).

Next, an operation for switching back from the detour route 7 to the optimum route 6 when the line failure of the optimum route 6 is recovered will be described.

First, the line failure of the optimum route 6 is recovered (26 in FIG. 4). The originating ATM switch 3 detects a change in the PNNI topology information by PNNI Hello packet switching, which is a known technique, along with the recovery of the line failure of the optimum route 6. Although this is an opportunity, although not specified in the prior art, in the present embodiment, the weight of the line is calculated for the optimal route 6 from which the line failure has been recovered, and the weight of the line is also recalculated for the detour route 7 that is currently detouring. The optimum route is selected by calculating and comparing the two. At this time, when calculating the weight of the detouring line,
The routing list saved in (17 in FIG. 3) or (24 in FIG. 4) is used.

As a result of comparing the weights of the two lines, if it is determined that the optimal route 6 from which the line failure has been recovered is optimal,
Using the call setup information stored in (14 in FIG. 3) or (21 in FIG. 4), a call setup message is created in the originating ATM switch 3, and call setup is performed on the optimal route 6 from which the line failure has been recovered. (27 in FIG. 5).

The destination ATM switch 5 that has received the call setting message from the calling ATM switch 3 transmits the call setting message to the destination terminal 2 according to the known technique. In the present embodiment, the destination ATM switch 5 is set in the call setting message. Departure and arrival AT
It is confirmed whether the M address and the return target ID 33 are stored in the destination ATM switch 5. If it is stored, the destination ATM switch 5 does not transmit the call setting message to the destination terminal 2, returns a call setting acceptance message to the calling terminal 1, and arrives at the detour route 7 in preparation for the route switching. The data transmission from the terminal 2 is buffered in the destination ATM switch 5 (the data transmission from the destination terminal 2 to the originating terminal 1 is interrupted). In the destination ATM switch 5, the routing list set in the call setup message (FIG. 7)
Is copied to the connection message and returned to the originating ATM switch 3 (28 in FIG. 5).

When the call setting is completed in the destination ATM switch 5, the routing table of the destination ATM switch 5 is provided with a port /
The VPI / VCI value is set. In the present embodiment, as shown in FIG.
/ VCI value only, the optimal route 6 and the detour route 7
Used for switching.

In the calling ATM switch 3 which has received the connection message from the called ATM switch 5, the connection message is transmitted to the calling terminal 1 in the known technology. In the present embodiment, however, in the stored call setting information, Check if the routing list has been saved. If it is stored, the connection message is not transmitted to the calling terminal 1, but data transmission from the calling terminal 1 to the detour route 7 is buffered in the calling ATM switch 3 in preparation for the route switching (calling terminal 1). , The data transmission in the two directions of the destination terminal is interrupted).

When the call setting is completed in the source ATM switch 3, the routing table of the source ATM switch 3 uses the port / address to the terminal side and the network side in the known technique.
Although the VPI / VCI value is set, in this embodiment, the network side port / VPI / V to the optimum route 6 is set as shown in FIG.
Only the CI value is set and used for switching between the optimum route 6 and the detour route 7.

The switching from the detour route 7 to the optimum route 6 from which the line failure has been recovered is not specified in the prior art, but in this embodiment, the switching is performed when the detour route 7 is cut off. A disconnection message is created for disconnection of the detour route 7 and transmitted to the destination ATM switch 5. At this time, “route switching” is newly defined as the disconnection reason, and is used as a trigger for route switching (29 in FIG. 5).

In the destination ATM switch 5, which has received the disconnection message from the source ATM switch 3, the disconnection message is transmitted to the destination terminal 2 in the known technique, but in the present embodiment, the disconnection reason is “route switching”. In this case, the disconnection message is not transmitted to the destination terminal 2. In this case, the detour route 7 and the optimal route 6 from which the line failure has been recovered
In order to perform the above-described route switching, the routes are switched by exchanging the network side port / VPI / VCI values of the bypass route 7 on the routing table and the optimal route 6 from which the line failure has been recovered as shown in FIGS. . Further, the contents of the output buffer (11 in FIG. 2) to the detour route 7 on the hardware are copied to the output buffer (12 in FIG. 2) to the optimal route 6 from which the line failure has been recovered. Although not specified in the prior art, in the present embodiment, the disconnection reason set in the disconnection message is copied to a disconnection response message and returned to the originating ATM switch 3 (30 in FIG. 5).

In the sending ATM switch 3 that has received the disconnection response message from the destination ATM switch 5, the disconnection response message is transmitted to the calling terminal 1 in the known technology, but in the present embodiment, the disconnection response message is set in the disconnection response message. If the disconnection reason is “route switching”, no disconnection response message is transmitted to the calling terminal 1. In this case, in order to perform the route switching between the detour route 7 and the optimal route 6 whose line failure has been recovered, the network side port / VPI / VCI values of the detour route 7 and the optimal route 6 whose line failure has been recovered on the routing table are shown. 13 is replaced as shown in FIG. Thus, the route is switched, and the contents of the output buffer (11 in FIG. 2) to the detour route 7 on the hardware are copied to the output buffer (12 in FIG. 2) to the optimal route 6 from which the line failure has been recovered. Thereafter, although not specified in the known art, in the present embodiment, transmission of buffered data is started (31 in FIG. 5).

Although the destination ATM switch 5 is not specified in the prior art, in the present embodiment, transmission of buffered data is started upon reception of data from the source ATM switch 3 (see FIG. 5). 32). With the above procedure, automatic failback of the fault detour is completed.

One of the effects of the present embodiment is as follows. When a call being communicated on the optimal route is bypassed due to a line failure in the optimal route, a very long distance or a line with a large number of ATM switch relay stages is selected as the bypass route, and the data transfer efficiency drops significantly. In addition, recovery from the line failure of the optimal route and switching back from the bypass line can be performed. The reason is that, when setting up a detour call due to a line failure, the call setting information is stored in the originating and terminating ATM switch, and the state change of the PNNI topology information is detected when the line failure is recovered, thereby re-detecting the optimum route. .

As described above, the present embodiment provides a configuration in which a call being bypassed due to a line failure is automatically switched back to the optimum route without disconnecting the call when the line failure is recovered. Things.

In the present embodiment, when a call communicating on the optimum route 6 is disconnected due to a line failure, and call setting is performed on the detour route 7 for call detour, call setting information and call setting Save the routing list used for. When the recovery of the line failure is detected from the change in the PNNI topology information, the line weights of the detour route 7 and the optimal route 6 from which the line failure has been recovered are compared (the weight of the line of the detour route 7 was saved at the time of call setup). Calculate using the routing list) and the optimal route 6 from which the line failure has recovered
Is determined to be optimal, a call is set to the optimal route 6 from which the line failure has been recovered, and switching between the optimal route 6 from which the line failure has been recovered and the detour route 7 enables switching back to the line before the detour. To

Next, a modification of this embodiment will be described. In the embodiment described above, in the configuration of FIG. 1, the calling terminal 1 sets the switchback target ID in the call setting message, whereas in the present modification, the calling ATM switch 3 sets the switchback target ID to the call setting message. Can be set to Thus, in the above-described embodiment, the specification in the user network interface unit is applied, but in the present modified example, it can be applied to the specification in the network-network interface unit.

[0082]

According to the system for automatically switching back to an alternate route in a PNNI network according to the present invention, a call that is communicating on the alternate route due to a line failure of the optimal route can be used when the route failure of the optimal route is recovered. Automatically switch back to the optimal route.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an automatic switchback system from a detour route in an ATM network according to the present invention.

FIG. 2 is a diagram illustrating a hardware configuration inside the ATM switch according to the embodiment;

FIG. 3 is a sequence diagram for explaining a part of the operation according to the embodiment;

FIG. 4 is a sequence diagram for explaining another part of the operation of the embodiment.

FIG. 5 is a sequence diagram for explaining still another part of the operation of the embodiment;

FIG. 6 is a diagram showing a switchback target ID information element set in the call setting message in the embodiment.

FIG. 7 is a diagram showing contents of a call setting message in the embodiment.

FIG. 8 is a diagram showing the content of a connection message in the present embodiment.

FIG. 9 is a diagram showing call setting information stored in a calling ATM switch according to the embodiment;

FIG. 10 is a diagram showing call setting information stored in a destination ATM switch according to the embodiment;

FIG. 11 is a diagram illustrating an image of a routing table in a source ATM switch and a destination ATM switch according to the embodiment;

FIG. 12 is a diagram illustrating another image of a routing table in a source ATM switch and a destination ATM switch according to the embodiment;

FIG. 13 is a diagram showing still another image of the routing table in the source ATM switch and the destination ATM switch in the present embodiment.

[Explanation of symbols]

 Reference Signs List 1 originating terminal 2 destination terminal 3 originating ATM switch 4 ATM switch 5 destination ATM switch 6 optimal route 7 detour route 8 switch unit 9 input buffer unit 10 output buffer unit 11 output buffer for detour route 12 output buffer for optimal route 33 cut Return target ID 34 Routing list

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/56

Claims (10)

(57) [Claims] (1)PNNI (Private Network)
rk-to-Network Interface)
PNNI network suitable forLine
Detour from the faulty first route and pass through the second route
The active call is transferred to the first route when the line failure of the first route is recovered.
A method for automatically switching back to a route, comprising: (a) providing a first and a second ATM switch;
And (b) a maximum between the first and second ATM switches.
Providing the first route as a suitable route; and (c) providing the first route between the first and second ATM switches.
Provide the second route as a detour route of the first route
(D) before the first and second ATM switches
During the communication on the second route, a line failure of the first route may occur.
(E) detecting the line number of the first route in the step (d).
When it detects a reinstatement,The first route from which the line failure has recovered
And the weight of each line of the second route
Steps to (Ae) The line fault calculated in the step (e)
Of the first route and the second route whose harm has been restored.
Comparing the weights; (Be) As a result of the comparison in the step (ae),
Judged that the first route from which the line failure was recovered was optimal
Between the first and second ATM switches.
Steps for setting up a call on the first route after the line failure has been recovered
And  (F) the second route from the first ATM switch
The transmission data to the buffer is buffered by the first ATM switch.
Before the second ATM switch.
The transmission data to the second route is transmitted to the second ATM switch.
Buffering at the
(G) after the step (f), disconnecting the second route;
(H) backing up at the first and second ATM switches.
The call setting is performed by the fallen transmission data.
Automatically switching back from a detour route in an ATM network, comprising the steps of:
And how. 2. A PNNI (Private Network)
rk-to-Network Interface)
In a PNNI network suitable for routing, a call that is communicating on a second route while bypassing the first route in which a line failure has occurred is connected to the first route when the line failure in the first route is recovered.
Automatically switching back to a route, comprising: (a) providing first and second ATM switches; and (b) the first as an optimal route between the first and second ATM switches. Providing a route; (c) providing the second route as a bypass route of the first route between the first and second ATM switches; and (i) providing the second ATM switch. when a line failure of the first route in the communication in the second route is detected to be recovered between the first route the line failure in the first ATM switch has recovered and the second
Calculating the weight of each line in the route; (ai) at the first ATM switch
(I) the recovery of the line failure calculated in step
Compare the weights of the lines of one route and the second route
And (bi) comparing the result of the (ai) step,
In the first ATM switch, the line failure is recovered.
If it is determined that the first route is optimal,
Wherein the step of failure generates a call setup message signals at first route recovers, the call setting message signal the generating (j) times
The second ATM via the first route where the line failure has been restored
And (k) buffering the transmission data from the second ATM switch to the second route in the second ATM switch in response to the call setup message signal. Stopping transmission to the second route; and (l) buffering transmission data from the first ATM switch to the second route in the first ATM switch and transmitting the data to the second route. And (m) a disconnection message for disconnecting the second route in the first ATM switch after the call setup corresponding to the call setup message signal transmitted in the step (j) is completed. Generating a signal; and (n) transmitting the generated disconnect message signal to the second
Transmitting the disconnection response message signal to the first ATM switch in response to the disconnection message signal; and transmitting the disconnection response message signal to the first ATM switch. Disconnecting the second route in response to the disconnection response message signal; and (q) responding to the disconnection response message signal to transmit the buffered transmission data in the step (l) to the first route. And (r) transmitting the buffered transmission data in the (k) step to the first route in response to the transmission data transmitted in the (q) step. Automatic return method from detour route in ATM network. 3. The method for automatically switching back from a detour route in an ATM network according to claim 1 , further comprising: (s) a call communicated on said second route between said first and second ATM switches. Transmitting a call setting message signal including a reversion target ID indicating that the call is a reversion target call to the first route when the line failure of the first route is recovered, from the first ATM switch to the second ATM switch Outputting to a switch, wherein the step (e) automatically switches back the call to be switched back from a detour route in an ATM network for performing the call setting. 4. The automatic switchback method from a detour route in an ATM network according to claim 3 , wherein the call setup message signal including the switchback target ID in the step (s) is the first ATM switch. A call setup message signal generated by the first terminal in the previous stage and including the generated switchback target ID is transmitted to the first AT.
A method for automatically switching back from a detour route in an ATM network in which an M switch inputs and outputs to the second ATM switch. 5. The method of automatically switching back from a detour route in an ATM network according to claim 3 , wherein the call setting message signal including the switchback target ID in the step (s) is the first ATM switch. The first ATM switch inputs the call setup message signal generated by the first terminal at the preceding stage of the above, and sets the switchback target ID in the input call setup message signal. How to switch back. 6. The method of automatically switching back from a detour route in an ATM network according to claim 1 , wherein in the step (d), based on PNNI topology information, that the line failure of the first route has been recovered. Automatic return method from detour route in ATM network to be detected. 7. according to any one of claims 1 to 6 AT
In the method for automatically switching back from a detour route in an M network, buffering of transmission data from each of the first and second ATM switches to the second route is performed for the first route from which the line failure has been recovered. The call setting is completed until the return from the second route to the first route is completed. The return from the second route to the first route is triggered by the disconnection of the second route. Automatic return method from detour route in ATM network to be implemented. 8. The method of automatically switching back from a detour route in an ATM network according to claim 1 , wherein the steps (e) , (ae) and (be) are performed between the first and second ATM switches. A method of automatically switching back from a detour route in an ATM network, which is performed during communication on the second route. 9. The method of automatically switching back from a detour route in an ATM network according to claim 1 , wherein when the call setup is completed in the ( be ) step, each of the first and second ATM switches is switched. For the routing table, the port value to the terminal side, V
PI (Virtual Path Identific)
ation: virtual path identifier) value and VCI
(Virtual ConnectionIdenti
setting a network-side port value, a VPI value, and a VCI value to the first route without setting a value of the first and second ATM switches. In each of the routing tables, the network-side port value, VPI value, and VCI value for the first route set in the step (e) are converted to the network side for the second route corresponding to the communication on the second route. Port value, V
A method for automatically switching back from a bypass route in an ATM network in which a communication route is switched from the second route to the first route by replacing the PI value and the VCI value in place of the PI value and the VCI value. 10. The method of automatically switching back from a detour route in an ATM network according to claim 1 , wherein said step (f) includes outputting to said second route in each of said first and second ATM switches. Buffering the transmission data in a buffer; and (h) in each of the first and second ATM switches, the transmission data buffered in the output buffer to the second route, A method for automatically switching back from a detour route in an ATM network in which communication is performed on the first route by copying to an output buffer for one route.