JP3259770B2 - Failure recovery method and transmission device by detecting / switching optical path end failure in wavelength division multiplexing transmission network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission device configuration method using a wavelength multiplexing technique and a fault recovery method in a wavelength division multiplexing network.

[0002]

2. Description of the Related Art With the spread of the Internet and multimedia communication, a demand for a large-capacity communication channel is increasing. 1
Wavelength division multiplexing (hereinafter, WDM) for multiplexing and transmitting a plurality of wavelengths on a single optical fiber.
The transmission technology described as ex) is expected as a technology for performing large-capacity communication. At the same time, "SONET, GR-1230-CORE, ISSUE3, D
ECEMBER 1996, Bellcore (published in December 1996, Bellcore,
Sonnet, GR-1230-Core, Issue 3) ", as well as a highly reliable protection method is required.
In the WDM transmission network, "AF Elrefaie,
"Multi-wavelength Survivable Ring Network Archite
ctures ", ICC '93, pp. 1245-1251 (1993, by I.C.I., AFC L.E., page 1245-1251, Multiwave Survival Ring Network Architecture).

A conventional WDM transmission network protection scheme will be described with reference to FIGS.
For the sake of simplicity, a bidirectional fiber is used as an expression below, but the function does not change even if it is separated as a unidirectional fiber.

FIG. 9 shows a configuration of a conventional transmission device. The transmission device shown in FIG. 9 is a wavelength division multiplex transmission device, and includes a line switch (Line SW) 110 connected to input / output ports 201-i and 202-i, and an input / output port 201- (i
+1), 202- (i + 1)
And connected to the line switches 110 and 111, respectively.
Signaling demultiplexing units 120 and 121 for multiplexing and demultiplexing signaling signals, and line switches 110 and 1
A wavelength division multiplexing / demultiplexing units 130 and 131, which are connected to each other and are provided to face each other, for wavelength division multiplexing of transmission signals and separation of wavelength division multiplexing signals;
0, 111, respectively, a failure detection unit 140, 141 for detecting a failure, a signaling processing unit 150 for processing a signaling signal, and a line switch 110,
And a switch (SW) control section 160 for controlling the control section 111. I / O ports 201-i, 201- (i + 1)
Is an input / output port connected to a working physical path connecting adjacent transmission devices. This input / output port 201
-i, 201- (i + 1) outputs a wavelength-division multiplexed signal obtained by multiplexing a working system of a virtual communication path (hereinafter referred to as a lightwave path) for connecting arbitrary transmission devices by using a wavelength. . The input / output ports 202-i and 202- (i + 1) are input / output ports similarly connected to the backup path.
i, 202- (i + 1) outputs a wavelength-division multiplexed signal obtained by multiplexing the backup lightwave path of the working lightwave path.

In a normal state where no failure occurs, the WDM input from the input / output ports 201-i and 201- (i + 1)
The signals are input to the signaling demultiplexers 120 and 121 via the line switches 110 and 111, respectively. Also, some WDM signals from the line switches 110 and 111 are input to the failure detection units 140 and 141. Signaling demultiplexing sections 120 and 121 separate the signaling signal from the transferred WDM signal and transfer the separated signal to signaling processing section 150, and transmit the remaining data WDM signal.
The signal is transferred to the wavelength division multiplexing / demultiplexing units 130 and 131. The data WDM signals input to the wavelength multiplexing / demultiplexing units 130 and 131 are separated into lightwave paths of each wavelength, and the lightwave paths of wavelengths terminated by the transmission device of FIG.
The lightwave paths of wavelengths output from 02 and not terminated are transferred to the wavelength division multiplexing / demultiplexing units 131 and 130, respectively.
The wavelength multiplexing / demultiplexing units 130 and 131 multiplex the lightwave paths of these wavelengths with the lightwave paths of the wavelengths input from the input / output ports 101 and 102 to generate a data WDM signal, and send the data WDM signal to the signaling multiplexing / demultiplexing units 120 and 121. Forward. Signaling demultiplexing sections 120 and 121 convert signaling signals transferred from signaling processing section 150 into data W
The WDM signal is formed by multiplexing with the DM signal. Thereafter, the WDM signal is output from the input / output ports 201-i and 201- (i + 1) via the line switches 110 and 111.

[0006] Next, W using the above-mentioned conventional transmission device is used.
A series of operations until the failure recovery ends when a failure occurs in the DM transmission network will be described with reference to FIGS.

FIG. 10 shows a configuration of a physical / lightwave path network. FIG. 10A shows transmission devices 210, 220, 230, 240, and 250 having the configuration shown in FIG.
To the working fibers 201-1 to
FIG. 2 shows the configuration of a physical network connected in a ring using 201-5 (hereinafter collectively referred to as 201) and spare fibers 202-1 to 202-5 (hereinafter collectively referred to as 202) which are spare paths of a lightwave path. ing. On the physical network shown in FIG. 10A, as shown in FIG. 10B, a lightwave path 260 is set between the transmission devices 220 and 230 using the working fiber 201.

Here, in the network shown in FIG. 10B, it is assumed that a failure has occurred in the working / standby fibers 201-3 and 202-3 between the transmission devices 220 and 230.
A series of operations up to failure recovery will be described with reference to FIGS. The operation of this failure recovery is basically, by connecting optical fibers in a ring shape, transferring a line path switching request information and a line path switching response information between transmission apparatuses when detecting a failure, By doing so, a route is set so as not to go through the obstacle by following the ring in reverse.

The failure detectors 141 and 140 of the transmission devices 220 and 230 detect a failure at time t0 due to a decrease in the amount of light of the WDM signal, and notify the signaling processor 150 in the transmission device of each. At time t1, the signaling processing unit 150 generates line route switching request information. Thereafter, the transmission devices 220 and 230
1, the line path switching request information 310-1, 311-1 and 320-1, 321-1 are respectively set as transfer destinations.
Is sent. The line route switching request information includes line route switching request information 310-2 to 310-4 and 321-2 to 321.
-4 is transmitted through each transmission device (time t2 to t
4), finally arrive at the transmission device of the other party. On this occasion,
Since a failure has occurred in the working / standby fibers 201-3 and 202-3, a route that does not include a failure section (for a working fiber, a route through 201-2 → 201-1 → 201-5 → 201-4 and The line route switching request information is transmitted via this reverse route).

At time t5, the signaling processing unit 150 of the transmission device 220 that has received the line route switching request information 321-4 sets the line switch 111 to the return mode via the switch control unit 160, and thereby the signaling multiplexing / demultiplexing unit 121 The connection between the active fiber 201-3 and the signaling demultiplexer 121 and the line switch 1
Change to connection with 10. Similarly, the signaling processing unit 150 of the transmission device 230 that has received the line path switching request information 310-4 sets the line switch 110 to the return mode via the switch control unit 160, and sets the signaling demultiplexing unit 120 and the working fiber 201-. The connection with 1 is changed to the connection between the signal demultiplexing unit 120 and the line switch 111. Thereafter, at time t6, the signaling processing units 150 of the transmission devices 220 and 230 respectively transmit the line route switching response information 330-1, 331-1 and 31-1.
40-1 and 341-1 are sent to each other as a destination. This line route switching response information is line route switching response information 3
30-2 to 330-4 and 341-2 to 341-4 are transferred via the respective transmission devices (time t7 to t9), and finally reach the other transmission device. As a result, as shown in FIG. 10C, via the transmission devices 210, 250, and 240,
A part of the lightwave path 260 is switched from the working path to the protection path using the protection fiber 202, and recovers from the failure.

[0011]

In a WDM transmission network, a light source of a wavelength to be used or a receiver may be damaged. In the conventional network system described above,
Since the failure is detected based on the WDM signal after the wavelength is multiplexed, there is a problem that the failure cannot be recovered from the above-described failure for each wavelength. Also, in order to avoid the use of the working fiber in the faulty section, the lightwave path is switched to the backup fiber in the adjacent transmission device in the faulty section, so that the transmission distance of the lightwave path becomes longer and the network scale is limited. There is.

Further, the above-mentioned conventional method may not be able to perform appropriate failure recovery even when two lightwave paths are set in the WDM transmission network.
There is a problem that.

The network shown in FIG.
While the same structure as those shown in (a), where the wavelength lambda _j
The lightwave path 401 (shown by a thick broken line) in FIG.
Is set using the working fiber 201 between
The lightwave path 402 having the wavelength λ _k is transmitted by the transmission devices 220 and 23.
It is set using the working fiber 201 between 0.
Then, it is assumed that a failure occurs between the transmission devices 220 and 230. Since this failure causes a decrease in the light amount of the WDM signal, this triggers the failure detection unit 140 or 141 of the transmission devices 210 to 240 to detect a failure on the working fiber 201. As a result, similarly to the case shown in FIG. 10B described above, as shown in FIG.
10-2, 411-1, 411-2, 420-1, 421-1, 4
30-1, 431-1, 440-1, 440-2, 441-1, 4
41-2, and further, the line route switching response information 45
0-1, 450-2, 451-1, 451-2, 460-1, 46
0-2, 461-1 and 461-2 are transferred. As a result, in the transmission devices 210 and 240, the line switches 111 and 110 on the failure side are switched. However, in this case, switching is performed between the transmission devices 210 and 2
40, the transmission device 2 as shown in FIG.
Failure of the lightwave path 402 terminated between 20, 230 cannot be recovered.

An object of the present invention is to provide a fault recovery method for detecting a fault for each lightwave path in a WDM transmission network and performing fault recovery for each lightwave path, and a WDM transmission apparatus for realizing the method. is there.

Another object of the present invention is to make it possible to reliably recover from a failure of the lightwave path if the failure can be recovered.
Further, the present invention provides a failure recovery method in which a lightwave path of an additional data path (hereinafter referred to as ET (Extra Traffc)) can be set up using a bypass network resource in a normal state where no failure occurs. It is also an object to provide a method.

[0016]

According to a first aspect of the present invention, there is provided a fault recovery method comprising a plurality of wavelength division multiplex transmission apparatuses (hereinafter, referred to as transmission apparatuses). A communication path composed of wavelengths (hereinafter, referred to as a lightwave path) can be set bidirectionally, and a failure occurs in a normally used lightwave path (hereinafter, referred to as a working lightwave path) in the working lightwave path. In a failure recovery method in a wavelength division multiplexing transmission network in which one or more lightwave paths used as detours (hereinafter referred to as backup lightwave paths) are predetermined, a transmission device that terminates at least one lightwave path includes: A lightwave path termination processing function that can monitor the state of a signal received using the lightwave path, and detect a failure from the monitoring result, and a backup function when a failure of the working lightwave path is detected. A lightwave path switching function for simultaneously setting one or a plurality of wavepaths, a bridge function for simultaneously transferring the same signal to a plurality of protection lightwave paths for a certain working lightwave path, and a plurality of protection lightwave paths for a certain working lightwave path And a selector function for selecting one of the backup lightwave paths from the network. If a failure occurs in a certain working lightwave path , the failed working lightwave path is regarded as a troubled lightwave path. The transmission device at the end that has detected the failure in the above (hereinafter referred to as a failure detection transmission device) transmits lightwaves to a transmission device at the other end of the failure lightwave path (hereinafter referred to as a transmission device facing the failure lightwave path). A plurality of backup lightwave paths for the working lightwave path are set as candidates using the path switching function, and a plurality of backup lightwave paths are set using the bridge function on the signal transmitting side of the faulty lightwave path. The same data signal is sent to the fault detection transmission device and the fault lightwave path opposite transmission device, and a plurality of backup lightwave paths are monitored using the lightwave path termination processing function. One or a plurality of available backup lightwave paths are selected from among the selected backup lightwave paths, and one of the selected backup lightwave paths is determined using the selector function, and is set to other than the determined backup lightwave path. Release the spare lightwave path.

A second fault recovery method according to the present invention comprises a plurality of wavelength division multiplexing transmission devices (hereinafter referred to as transmission devices), and a communication comprising an arbitrary physical wavelength in an arbitrary section between the transmission devices. A path (hereinafter, referred to as a lightwave path) can be set bidirectionally, and is used as a detour in the case where a failure occurs in the working lightwave path with respect to a normally used lightwave path (hereinafter, referred to as a working lightwave path). that optical path (hereinafter, preliminary light wave and path) is predetermined or higher one, and transfers the control information to switch from a desired preliminary light wave path setting and release of information and working light wave path when a failure to the backup optical path signaling channel, or in the failure recovery method in a wavelength division multiplexing transmission network signaling path multiplexed the signaling channel is set between the transmission apparatus, small when A transmission device that terminates one lightwave path can monitor a signal state received using the lightwave path, detect a failure from the monitoring result, and detect a failure in the working lightwave path. Sometimes, one or a plurality of the backup lightwave paths can be set at the same time, a lightwave path switching function, a bridge function for simultaneously transferring the same signal to a plurality of the backup lightwave paths for a certain working lightwave path, and a plurality of the lightwave paths for a certain working lightwave path. A selector function capable of selecting one standby lightwave path from the standby lightwave path, and a signaling processing function of exchanging control information for setting / selecting the standby lightwave path using a signaling channel, and when the optical path fails, the working optical path in which the failure has occurred as a failure optical path, failure of a fault optical path A transmission device at the end detected using the lightwave path termination processing function (hereinafter, referred to as a failure detection transmission device) selects one or a plurality of backup lightwave path candidates that can be set from a plurality of backup lightwave paths, and outputs a failure lightwave. Notifying the transmission device at the other end of the path (hereinafter referred to as a faulty lightwave path opposite transmission device) of backup lightwave path setting request information including backup lightwave path candidate information selected as settable, When the standby light path setting request information is received, the standby light path candidate is extracted and the notified standby light path is set to the receivable state, and then the standby light path setting including the reception setting information of the standby light path is set. The failure detection transmitting apparatus that has transmitted the response information and received the standby lightwave path setting response information extracts the standby lightwave path reception setting information from the standby lightwave path setting response information, and confirms the reception setting. The same signal branched to the recognized backup lightwave path is transmitted, and the reception state of the plurality of backup lightwave paths is monitored to select one or more usable backup lightwave paths, and the available backup lightwave path is selected. The backup lightwave path selection result information including the path information is transmitted to each other, and the failure detection transmission device and the failure lightwave path opposite transmission device receive the backup lightwave path selection result information, and extract usable backup lightwave path information.
By comparing the backup lightwave path information with the backup lightwave path information selected by the own transmission apparatus, a backup lightwave path to be used is uniquely determined from a plurality of available backup lightwave paths, and the determined backup lightwave path information is determined. Notifying each other of the backup lightwave path selection result response information including the failure detection transmission device and the failure lightwave path opposite transmission device, upon receiving the protection lightwave path selection result response information, holding the determined backup lightwave path setting and determining Release the other set spare lightwave paths other than those.

A first transmission apparatus according to the present invention comprises a plurality of wavelength division multiplex transmission apparatuses (hereinafter referred to as transmission apparatuses), and a communication path comprising an arbitrary physical wavelength in an arbitrary section between the transmission apparatuses. (Hereinafter referred to as a lightwave path) can be set in both directions, and is used as a detour when a failure occurs in the working lightwave path with respect to a normally used lightwave path (hereinafter referred to as a working lightwave path). signaling optical path (hereinafter, preliminary light wave and path) is predetermined or higher one, and transfers the control information to switch to the spare light wave path from the desired pre-light wave path setting and release of information and working light wave path in case of failure channel, or the transmission device signaling path multiplexed such signaling channel is used in wavelength division multiplexing transmission network that is set between the transmission device, A wavelength division multiplexing / demultiplexing unit that separates the long multiplexed signal into lightwave paths for each wavelength, and multiplexes the transmitted lightwave path and the lightwave path newly inserted from the own transmission device among the separated lightwave paths; The lightwave path separated by is transmitted, the lightwave path terminated by the own transmission device is taken into the own transmission device, and the lightwave path not terminated by the own transmission device is transferred to the wavelength division multiplexing / demultiplexing unit. ADM that transfers generated lightwave path to wavelength division multiplexer
Unit, a lightwave path switch unit for switching the path of the lightwave path captured and transferred by the ADM unit and the lightwave path generated by the own transmission device, and terminated by the own transmission device transferred from the lightwave path switch unit A lightwave path termination processing unit for detecting a failure of the lightwave path to be performed and terminating the lightwave path generated by the own transmission device, and a signaling channel or the own transmission device from the lightwave path transferred from the lightwave path termination processing unit. A signaling multiplexing / demultiplexing unit for multiplexing a signaling channel on the generated lightwave path, and a signaling multiplexing / demultiplexing unit for splitting the data signal of the lightwave path starting from its own transmission device into one signaling multiplexing / demultiplexing unit or splitting the data signal into a plurality of signaling multiplexing / demultiplexing units simultaneously And selects one of the lightwave path data signals transferred from the plurality of signaling And the failure information from the lightwave path termination processing unit and the information transferred from another transmission device by the signaling channel demultiplexed by the signaling multiplexing / demultiplexing unit. Generates or processes the information and notifies the signaling multiplexing / demultiplexing unit of the information, transfers the information to another transmission device through a signaling channel, and controls the ADM unit, the lightwave path switch unit, and the selector / bridge unit to transmit the information. A signaling processor for changing the route and / or wavelength of the lightwave path passing through the device, thereby setting a backup lightwave path for the faulty lightwave path and switching from the working lightwave path to the protection lightwave path; Upon receiving a lightwave path selection request, one or more backup lightwaves If a backup candidate is selected and a backup lightwave path selection decision request including a plurality of backup lightwave path candidate information is received from the signaling processing unit, one is selected from the plurality of backup lightwave paths and the selected result is notified to the signaling processing unit. A backup lightwave path selection unit.

A second transmission apparatus according to the present invention comprises a plurality of wavelength division multiplex transmission apparatuses (hereinafter, referred to as transmission apparatuses), and a communication path comprising an arbitrary physical wavelength in an arbitrary section between the transmission apparatuses. (Hereinafter referred to as a lightwave path) can be set in both directions, and is used as a detour when a failure occurs in the working lightwave path with respect to a normally used lightwave path (hereinafter referred to as a working lightwave path). signaling optical path (hereinafter, preliminary light wave and path) is predetermined or higher one, and transfers the control information to switch to the spare light wave path from the desired pre-light wave path setting and release of information and working light wave path in case of failure channel, or the transmission device signaling path multiplexed such signaling channel is used in wavelength division multiplexing transmission network that is set between the transmission device, A wavelength division multiplexing / demultiplexing unit that separates the long multiplexed signal into lightwave paths for each wavelength, and multiplexes a transmitted lightwave path and a lightwave path newly inserted from the own transmission device among the separated lightwave paths; The multiplexed signal is separated into a lightwave path for signaling path transfer and a lightwave path for data transfer, and the separated lightwave path for data transfer is transferred as an input signal to the wavelength division multiplexing / demultiplexing unit. A signal path multiplexing / demultiplexing unit for multiplexing with a lightwave path and a WDM signal transferred from a wavelength division multiplexing / demultiplexing unit; Terminates the lightwave path, separates the signaling channel to be processed from the signaling path, and transmits the signaling channel that is not processed In both cases, the optical path for signaling path transfer and the signaling channel are remultiplexed with the signaling channel on which the signaling processing has been performed in the own transmission apparatus to generate a lightwave path for signaling path transfer, and then to the signaling path demultiplexing unit. The lightwave path separated by the signaling path termination processing unit and the wavelength division multiplexing / demultiplexing unit to be transferred is transferred, the lightwave path terminated by the own transmission device is taken into the own transmission device, and the lightwave path not terminated by the own transmission device is set to the wavelength. Transfer to the demultiplexer,
Further, the ADM unit transfers the lightwave path generated by the own transmission device to the wavelength division multiplexer, the lightwave path captured and transferred by the ADM unit, and the switching of the lightwave path generated by the own transmission device. A lightwave path switch unit, a lightwave path termination processing unit that detects a failure of the lightwave path terminated by the own transmission device transferred from the lightwave path switch unit, and performs a termination process of the lightwave path generated by the own transmission device; The own transmission apparatus transfers the data signal of the lightwave path serving as a starting point to one signaling demultiplexing unit or to split the data signal and transfer the data signal to a plurality of signaling demultiplexing units at the same time, and from the plurality of signaling demultiplexing units. A selector / bridge unit that selects one of the data signals of the lightwave path and takes it into its own transmission device; Receives information transferred from another transmission device by the signaling channel separated by the demultiplexing unit, and generates or terminates or processes the information related to the setting or selection of the backup lightwave path, and sends the result to the signaling path demultiplexing unit through the signaling channel. The path and / or wavelength of the lightwave path passing through the own transmission apparatus is changed by controlling the ADM unit, the lightwave path switch unit, and the selector / bridge unit to transfer the lightwave path to another transmission apparatus, thereby notifying the failure lightwave path. The setting of the backup lightwave path and switching from the working lightwave path to the protection lightwave path, a signaling processing unit, and upon receiving a protection lightwave path selection request from the signaling processing unit, selects one or more protection lightwave path candidates and performs signaling. Processing unit decides backup light path selection including multiple backup light path candidate information Upon receiving a request to select one of the plurality of preliminary light wave path, having a spare light wave path selecting section for notifying the selected result to the signaling processor.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings.

<< Failure Recovery Method >> First, a failure recovery method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows transmission devices 510, 520, 530, 54
5 shows a WDM transmission network using 0,550. FIG. 1 (a) is a physical network connection diagram, and FIG. 1 (b)
Denotes a network of lightwave paths (hereinafter referred to as working lightwave paths) used at normal times using the wavelengths λ _i and λ _j .

As shown in FIG. 1A, transmission devices 510,
520, 530, 540 and 550 are bidirectional fibers
501-1 to 501-5 (hereinafter referred to collectively as 501)
), And connected in a ring shape using 502-1 to 502-5.
Have been. On the physical transmission network shown in Fig. 1 (a)
Is transmitted via the transmission device 550 as shown in FIG.
Wavelength λ set between transmission devices 510 and 540_iWorking
Via the lightwave path 560-N and the transmission devices 520 and 530
Λ set between the transmission devices 510 and 540 _iPresent
Lightwave path 561-N and transmission devices 510, 550, 54
Wave set between transmission devices 520 and 530 via 0
Long λ_jWorking optical path 570-N and transmission devices 520 and 5
Wavelength λ set between 30_jWorking lightwave path 571-N
, A total of four working lightwave paths are set. here
And the wavelength λ_jIs shown by a thick solid line, and the wavelength λ_iLight of
The wave path is indicated by a bold dashed line. All working lightwave paths 5
60-N, 561-N, 570-N, and 571-N
The setting is made by using the driver 501.

Each working lightwave path 560-N, 561
In -N, 570-N, and 571-N, a lightwave path used as a detour in the event of a failure (hereinafter referred to as a backup lightwave path) has a span direction (the same direction as the working lightwave path) on the bidirectional fiber 502. And the ring direction (the direction opposite to the working lightwave path). However, it is assumed that the backup lightwave path has not been set at this time. In this example, the working lightwave path 5
It is assumed that the wavelengths of the backup lightwave paths 60-N and 561-N are the same λ _i , and the working lightwave paths 570-N and 57
1-N and the wavelength of the backup lightwave path for them are the same λ _j
And

Here, the wavelength of the working lightwave path and the wavelength of the protection lightwave path corresponding thereto are the same, but these wavelengths may be different. In addition, although a single physical wavelength is used between the physical links on the path of the lightwave path in order to form one lightwave path, this may be a combination of different wavelengths. That is, it is only necessary that wavelength resources are independently assigned to the working lightwave path and the protection lightwave path. In consideration of these, a wavelength group including the wavelengths of the working lightwave path and the backup lightwave path is defined as a wavelength group, and is used below. The example shown here corresponds to a case where two wavelength groups are used and the number of wavelengths constituting each wavelength group is one.

Transmission devices 510, 520, 530, 54
Although the configuration of 0,550 will be described later, each transmission device is a wavelength division multiplex transmission device, and transmits the same data signal as an optical path termination processing function for detecting a failure of an optical path terminated by its own transmission device. Selector / bridge function for selecting one of a plurality of backup lightwave paths and transferring the same data signal to the plurality of backup lightwave paths, lightwave path switching function for switching lightwave paths, and signaling processing function for lightwave path control information exchange And The signaling processing function is provided for each wavelength group, and each transmission device 510, 520, 530, 54
It is assumed that 0,550 has at least a signaling processing function of the wavelength group of the lightwave path terminating in its own transmission device. Further, it is assumed that a signaling channel for transferring lightwave path control information is set in units of bidirectional fibers between adjacent transmission apparatuses having the same wavelength group.

Hereinafter, as shown in FIG.
A case where a fiber failure occurs in the bidirectional fiber 501-3 between the 20, 530 will be described.

This obstacle causes the bidirectional fiber 501-3.
A failure occurs in the working lightwave paths 561-N and 571-N that pass through the communication paths, and the failure is caused by lightwave path termination processing of the transmission devices 510, 540, 520, and 530 at both ends of the working lightwave paths 561-N and 571-N. Detected using function. The transmission devices 510, 520, 530, 540 that have detected a failure activate a failure recovery process. The failure recovery process is performed for each wavelength group.

FIGS. 2 and 4 show the failure recovery information exchange sequence. FIG. 2 is a failure recovery information exchange sequence of the wavelength group of wavelength λ _i , and FIG. 4 is a failure recovery information exchange sequence of the wavelength group of wavelength λ _j . The fault recovery information exchange sequence of each wavelength group is executed independently and in parallel. Note that the exchange of the failure recovery information is performed between the transmission devices where the lightwave paths of the same wavelength group are terminated, using the respective signaling processing functions. Hereinafter, for simplicity of description, the notation of the signaling processing function is omitted. Also in this example,
Two directions, the span direction and the ring direction, for the faulty working lightwave path
Assume that there are two backup lightwave paths.

First, the failure recovery information exchange sequence and the path switching operation of the wavelength group of the wavelength λ _{i in} FIG. 2 will be described.

Transmission device 510 that detected a failure at time t0
And 540 select one or more backup lightwave path candidates that can be used according to the usage status of network resources,
With respect to the route of the candidate preliminary lightwave path (in this example, the preliminary lightwave path in the span direction and the ring direction), the time t
In step 1, the backup lightwave path setting request information 610, 611 and 620, 621 including the backup lightwave path candidate information are transmitted toward each other.

As a result, the transmission devices 510 and 540 transmit the backup lightwave path setting request information 6 from the ring direction at time t3.
21 and 610, and at time t4, backup lightwave path setting request information 620 and 611 from the span direction, respectively. Backup lightwave path setting request information 620, 62
The transmission device 510 that has received 1 and 610 and 611 respectively
And 540 extract the backup lightwave path candidates included in the backup lightwave path setting request information, and use the respective lightwave path switching functions and lightwave path termination processing functions to put the data transferred on the backup lightwave path into a receivable state. Set. In this example,
The transmission devices 510 and 540 set the data transferred using two backup lightwave paths in the ring direction and the span direction to a receivable state.

Thereafter, at time t5, the transmission devices 510 and 540 set the backup lightwave path setting response information 630, 631 and 640, 641 including the backup lightwave path setting result.
To each other. The transmission devices 510 and 540 operate at time t.
7, the standby lightwave path setting response information 641 and 630 are received, respectively, and at time t8, the standby lightwave path setting response information 640 and 631 are received.
The setting of the receiving side of the backup lightwave path candidates between 40 is confirmed.
Thereafter, the transmission devices 510 and 540 bridge the data to be transferred using the selector / bridge function and transfer the data to the respective backup lightwave path candidates. By the above operation,
At time t8, bidirectional backup lightwave paths are set in both the ring direction and the span direction. Transmission devices 510, 540
Monitors the status of the set backup lightwave path candidates using the lightwave path termination processing function, and selects one or more available backup lightwave paths among them.

Next, the transmission devices 510 and 540
9, the preliminary lightwave path selection result information 65
0,651 and 660,661 respectively. The transmission device 5 that has received such information at times t11 and t12
10, 540 compares the backup lightwave path candidate selected by the own transmission device with the backup lightwave path candidate selected by the opposing transmission device, and uniquely determines the backup lightwave path by the same backup lightwave path determination process. After that, only one determined backup lightwave path is connected using the selector / bridge function. Thereafter, at time t13, the transmission device 51
0, 540 are backup lightwave path selection result response information 6
70, 671 and 680, 681. At time t15, standby lightwave path selection result response information 681, 670 is received. At time t16, standby lightwave path selection result response information 68.
Upon receipt of 0,671, the fault recovery process is complete.
The setting of the backup lightwave path candidate which has been selected as a candidate but has not been determined is set as the backup lightwave path selection result information 650, 651, 6
60, 661 is received, the backup lightwave path is uniquely determined, and the backup lightwave path is set using the selector / bridge function, or the backup lightwave path selection response information 670, 6
It is released when 71,680,681 is received. At this time, the network resources of these backup lightwave path candidates can be returned to the settings before time t0.

FIG. 3 shows the wavelength λ in the working lightwave path 561-N.
The change of the lightwave path network from the occurrence of the failure to the recovery of the wavelength group _i is shown. FIG. 3A shows the lightwave path network at time t0 described above, FIG. 3B shows the lightwave path network after time t8 to t12, and FIG. 3C shows the lightwave path network after time t16. In this example, finally, the preliminary lightwave path 561-R in the ring direction
Suppose M is determined. As shown in FIG.
At t12, backup lightwave paths 561-RM and 561-R are set in the ring direction and the span direction, respectively. Also, after time t16 when the backup lightwave path 561-RM in the ring direction is determined, the backup lightwave path 561-R in the span direction is used.
Is released as shown in FIG. 3 (c).

FIG. 4 shows a failure recovery information exchange sequence and a path switching operation of the wavelength group of the wavelength λ _j . The fault recovery information exchange sequence and the path switching operation of the wavelength group of the wavelength λ _j are the same as those in the wavelength group of the wavelength λ _i shown in FIG. , 621 and their response information 630, 631, 640, 641 and backup lightwave path selection result information 650, 651, 660, 661 and their response information 670, 671, 680, 681. Is different. Figure 5 shows a variation of the light wave path network to the fault recovery from failure of the wavelength group of the wavelength lambda _j working light wave path 571-N. Here, it is assumed that the backup lightwave path 571-RM in the ring direction is finally determined.
5A shows the state of the lightwave path network at time t0 in FIG. 4, FIG. 5B shows the state of the lightwave path network after time t20 in FIG. 4, and FIG. 5C shows the state after time t20 in FIG. As shown in FIG. 5B, at time t10 to t15, two backup lightwave paths 571-RM and 571-R in the ring direction and the span direction are set, and the backup lightwave path 571-RM in the ring direction is determined. After time t20, the spare lightwave path 5 in the span direction
71-R is released as shown in FIG. 5 (c).

Backup lightwave path setting request information 610, 61
1, 620, 621 may be transferred while including only the backup lightwave path candidate information that is the same path as the transfer path, or may be transferred while including all the backup lightwave path candidates. Similarly, in the case of transmitting the backup lightwave path setting response information 630, 631, 640, 641, even if the transmission includes the setting status of the backup lightwave path candidate that is the same path as the transfer path, the information is transferred.
The information may be transferred including the setting status of all the backup lightwave path candidates.

Backup lightwave path setting request information 610, 61
1,620,621 and backup lightwave path setting response information 63
When 0, 631, 640, and 641 transfer information for each of the backup lightwave path candidates on the same route as the transfer route, the backup lightwave path setting request information 610, 611, and 610 in the case of a one-way fiber failure. 620 and 621 are transmitted, the backup lightwave path setting response information 630, 631, 64
0,641 will not be received. Therefore, if the standby lightwave path setting response information 630, 631, 640, 641 cannot be received within a certain time after outputting the standby lightwave path setting request information 610, 611, 620, 621, the standby lightwave path Need to be excluded from the candidates.

Preliminary lightwave path selection result information 660, 66
Similarly, even if 1,670 and 671 are respectively transferred including only the information on the backup lightwave path candidates which are the same as the transfer path, they are also transferred including the information on all the backup lightwave path candidates. It does not matter.
Further, preliminary lightwave path selection result information 660, 661, 67
It is not always necessary to narrow down the definable backup lightwave path candidates notified by 0,671 to one. When a plurality of determinable backup lightwave paths are included, each transmission device that switches from the working lightwave path to the backup lightwave path receives the backup lightwave path selection result information 660, 661, 670, and 671,
A backup lightwave path is uniquely determined by the same backup lightwave path determination process.

In the failure recovery method described in the present embodiment, when a failure is detected, or when a plurality of backup lightwave path candidates are set for a failed working lightwave path, the own transmission apparatus is When a plurality of the determined preliminary lightwave path candidate information and a plurality of the determined preliminary lightwave path candidate information determined by the opposing transmission device overlap, it is necessary to select an appropriate standby lightwave path candidate from the plurality of candidates. The backup lightwave path is selected based on the number of hops, propagation distance, network use efficiency, and the like. In addition, when the same data is transmitted and received using a plurality of backup lightwave paths, the fact that the error rate of the lightwave path is equal to or less than a reference may also be a factor for selection.

When the transmission apparatus that has detected the failure of the working lightwave path selects one or a plurality of backup lightwave path candidates, additional or auxiliary data is used by using a part or all of the network resources of the backup lightwave path candidates. A transmission device that has established a lightwave path for transmission (hereinafter referred to as an ET lightwave path), or a backup lightwave path that can be set using part or all of the same network resources as the backup lightwave path candidate. If there is a terminating transmission device of the working lightwave path, the transmission device that terminates the failed working lightwave path also sends the protection lightwave path setting request information and the protection lightwave path setting response to those transmission devices. The information, the standby lightwave path selection result information, and the standby lightwave path selection result response information are notified.

When the ET lightwave path terminating transmission device that terminates the ET lightwave path receives the protection lightwave path setting request information,
The ET lightwave path is cut off and the backup lightwave path is set.
In addition, the ET lightwave path terminal transmission device cancels other than the determined backup lightwave path notified by the backup lightwave path selection result response information, and only the lightwave paths that do not use the network resources of the determined backup lightwave path before time t0. Settings can be returned.

Further, the transmission device for terminating another working lightwave path using part or all of the network resources of the selected protection lightwave path as a protection lightwave path, receives the protection lightwave path setting request information, and receives the working lightwave path information. A backup lightwave path that shares network resources with the backup lightwave path candidate selected from the backup lightwave path candidates for the path is deleted. When the backup lightwave path is determined, the transmission device adds the deleted backup lightwave path as a candidate except for the determined backup lightwave path.

An ET lightwave path terminating transmission device or a transmission device for terminating another working lightwave path that uses a part or all of the network resources of the selected backup lightwave path as a backup lightwave path transmits the backup lightwave path control information. Even when the information is received, the information is transferred to the transmission device where the information is terminated without rewriting.

Further, in the present embodiment, switching from the working lightwave path to the backup lightwave path can be realized by wavelength switching in addition to physical path switching. In this case, the wavelength group is composed of a plurality of wavelengths,
The switched backup lightwave path may be physically the same path as the working lightwave path.

As described above, a wavelength group is formed by the wavelengths of the working lightwave path and the protection lightwave path, a fault is detected at the lightwave path end, and the lightwave path is switched for each wavelength group. Disaster recovery can be performed.

<< Configuration Example 1 of Transmission Device >> Next, a configuration of a transmission device for performing the above-described failure recovery method will be described. FIG. 6 is a block diagram illustrating an example of a configuration of a transmission device used as the transmission devices 510, 520, 530, 540, and 550 in the transmission network of FIG. It is assumed that the WDM transmission network to which the transmission device shown in FIG. 6 is applied has four wavelengths. In this transmission device, a data signal and a signaling channel are multiplexed on a lightwave path. This example is an example in which lightwave paths of two wavelength groups are terminated.

The transmission apparatus shown in FIG. 6 includes wavelength division multiplexers 1010 to 1013 for performing wavelength division multiplexing and wavelength separation, and an ADM (add-drop) for connecting to both wavelength division multiplexers 1010 and 1012 to perform optical branching and coupling. A multiplexer;
ADM 1 connected to both add-drop multiplexers 1020 and 1022 and wavelength multiplexing / demultiplexing units 1010 and 1012
021, 1023, a lightwave path switch 1040 connected to the ADMs 1020, 1021, and ADMs 1022, 1
The lightwave path switch 1041 connected to the lightwave path switch 023, the lightwave path termination processing units 1060 and 1061 connected to the lightwave path switch 1040 to execute the lightwave path termination processing, and the lightwave path termination processing connected to the lightwave path switch 1041. The lightwave path termination processing units 1062 and 1063 to be executed, the signaling demultiplexing units 1070 to 1073 connected to the respective lightwave path switches 1060 to 1063 to multiplex and demultiplex signaling signals, the lightwave path termination processing units 1060 and 1061, and Signaling demultiplexing section 107
0, 1071, a signaling processing unit 1050 for performing signaling processing, and a lightwave path termination processing unit 106.
2, 1063 and signaling demultiplexing sections 1072, 1
073, a signaling processing unit 1051 for performing signaling processing, and a switch control unit 103 for controlling the ADMs 1020, 1021 and the lightwave path switch 1040.
0, a switch control unit 1031 for controlling the ADMs 1022 and 1023 and the lightwave path switch 1041, a protection lightwave path selection unit 1080 for selecting a protection lightwave path, and a cell connection to the signaling demultiplexing units 1070 and 1071.
R> lector / bridge section 1090 and selector / bridge section 1091 connected to signaling multiplex / demultiplex sections 1072 and 1073.

The lightwave path termination processing units 1060 to 1060
63 and the selector / bridge units 1090 and 1091
It is arranged only in the lightwave path terminated by this transmission device.
Also, the lightwave path switches 1040 and 1041, the switch controllers 1030 and 1031 and the signaling processor 105
0, 1051 is prepared for each wavelength group terminated by this transmission apparatus.

I / O ports 501-i, 501- (i + 1) (hereinafter abbreviated as 501), 502-i, 502- (i + 1)
A WDM signal input from a WDM signal (hereinafter abbreviated as 502) is separated into lightwave paths of each wavelength by wavelength multiplexing / demultiplexing units 1010 to 1013. The separated lightwave path is
It is classified into a lightwave path of a wavelength group passing through this transmission device and a lightwave path of a terminated wavelength group. Of these, the lightwave path of the wavelength group that passes through this transmission device is directly transmitted to the desired wavelength division multiplexers 1010 to 1013.
Transferred to

On the other hand, the lightwave path of the wavelength group terminated by this transmission device is transferred to the ADMs 1020 to 1023. Of these, the lightwave path terminated by this transmission device is
The signals are dropped by the ADMs 1020 to 1023 and transferred to the signaling multiplexing / demultiplexing units 1070 to 1073 via the lightwave path switches 1040 and 1041 and the lightwave path terminating units 1060 to 1063. Is separated into The signaling channel is transferred to signaling processing units 1050 and 1051, and the data signal is transferred to selector / bridge units 1090 and 1091. The selector / bridge unit 1090 selects one of the data signals input from the signaling demultiplexing units 1070 and 1071 and selects a desired input / output port 100
Output to 1. Similarly, selector / bridge section 1091
Selects one of the data signals input from the signaling demultiplexing units 1072 and 1073 and outputs it to a desired input / output port 1002.

Of the lightwave paths of the wavelength group terminated by the transmission device, the lightwave paths not terminated by the transmission device are transmitted through the ADMs 1020 to 1023 and transferred to the wavelength division multiplexers 1010 to 1013.

Further, input / output ports 1001 and 1002
Is input to the selector / bridge 1
In 090 and 1091, the packet is transferred to a desired signaling demultiplexer 1070 to 1073. When transmitting the same signal to a plurality of backup lightwave paths, input / output data signals are branched at selector / bridge sections 1090 and 1091 to desired signaling demultiplexing sections 1070 to 1073.
Transferred to After that, the data signal is multiplexed with the signaling channel in the signaling multiplexing / demultiplexing units 1070 to 1073, and thereafter, the lightwave path termination processing units 1060 to 1
At 063, the light is converted into a desired lightwave path, and the lightwave path switches 1040 and 1041 are used to convert the ADMs 1020 to 1020.
The wavelength division multiplexing / demultiplexing units 1010 to 101 inserted at 1023
3 is transferred.

The wavelength division multiplexing / demultiplexing units 1010 to 1013 multiplex the lightwave paths transmitted / inserted by this transmission device and
It is transferred to the input / output ports 501 and 502 as an M signal.

The lightwave path termination processing function at the lightwave path end in the transmission apparatus used in the failure recovery method described with reference to FIGS.
3, and a signaling processing function for performing path path switching control such as lightwave path setting request information exchange is also realized by the signaling processing units 1050 and 1051. The signal processing units 1050 and 1051 perform the lightwave path switching function when a failure occurs.
This is realized by switching the ADMs 1020 to 1023 and the lightwave path switches 1040 and 1041 via the switches 30 and 1031. If the switching from the working lightwave path to the backup lightwave path is the switching of the physical path, the lightwave path switch 10
40 and 1041 are desirably realized by a space switch, and if the switching is wavelength switching, it is desirably a wavelength conversion switch. When both are mixed, the lightwave path switches 1040 and 1041 must have both switch functions.

According to the above-described fault recovery method, when a fault occurs, the same signal is transmitted to a plurality of backup lightwave paths. A plurality of backup lightwave paths are set on the transmission network, and data signals input from the input / output ports 1001 and 1002 are branched using the selector / bridge units 1090 and 1091 and transferred to the respective backup lightwave paths. realizable. On the other hand, regarding reception,
ADMs 1020 to 1023 and lightwave path switch 104
0, 1041 to set a plurality of backup lightwave paths on the WDM transmission network, and receive these lightwave paths by the lightwave path termination processing units 1060 to 1063, respectively, thereby forming data signals from the plurality of backup lightwave paths. Can be received. When the backup lightwave path is uniquely determined, it can be connected to one backup lightwave path by controlling the selector / bridge units 1090 and 1091. Also, after uniquely determining the backup lightwave path,
The signaling processing units 1050 and 1051 are connected to the ADMs 102 to 102 via the switch control units 1030 and 1031.
By restoring the connection of the backup lightwave path determined by controlling the lightwave path switch 3 and the lightwave path switches 1040 and 1041 before the occurrence of the failure, it is possible to recover the lightwave path irrelevant to the failure recovery and the failure occurrence.

The backup lightwave path selection unit 1080 has backup lightwave path information for each wavelength group, and responds to a request for selection of a backup lightwave path from the signaling processing units 1050 and 1051 by using the number of hops among unused backup lightwave paths. One or more backup lightwave path candidates are notified based on criteria such as transmission distance and efficient use of network resources. The backup lightwave path selection unit 1080
If the backup lightwave path selection result information from the lightwave path terminal transmission device at the other end notified from 50 and 1051 is partially or entirely different from the backup lightwave path selected by itself, both backup lightwave path candidates are compared. Thus, the backup lightwave path is uniquely determined and notified to the signaling processing units 1050 and 1051.

When the transmission apparatus shown in FIG. 6 terminates the ET lightwave path in a normal state using part or all of the network resources of the backup lightwave path as the ET lightwave path, the signaling of this transmission apparatus is performed. Processing unit 1
050 and 1051 are ADMs 102 that drop the ET lightwave path when the lightwave path setting request information is received.
0 to 1023 are switched to the transparent state to eliminate the ET lightwave path and provide network resources for failure recovery.

Further, signaling processing sections 1050, 1
051 receives the standby lightwave path selection result response information, and receives the ADMs 1020 to 1023 or the lightwave path SW1.
By controlling 040 and 1041, the setting of the backup lightwave path candidates other than the finally determined backup lightwave path can be returned to the state before the occurrence of the failure.

Lightwave path termination processing units 1060 to 1063
It is desirable to prepare as many backup lightwave path candidates as the number of backup lightwave path candidates for the working lightwave path, but it is conceivable that there are more backup lightwave path candidates in actual operation. In this case, the state of all the backup lightwave path candidates is monitored by controlling the lightwave path switches 1040 and 1041 to temporally switch the connection between the backup lightwave path and the lightwave path termination processing units 1060 to 1063. Can be. In addition, the lightwave path termination processing units 1060 to 1063 can be arranged on the lower side of the selector / bridge units 1090 and 1091.

With such a transmission apparatus configuration, the failure recovery method shown in FIGS. 1 to 5 can be realized.

<< Configuration Example 2 of Transmission Apparatus >> FIG. 7 shows transmission apparatuses 510, 520, 53 in the transmission network of FIG.
It is a block diagram which shows an example of a structure of the transmission apparatus used as 0,540,550. The transmission device shown in FIG.
This is used for implementing the above-described failure recovery method. The WDM transmission network to which this transmission apparatus is applied is composed of five wavelengths, and four wavelengths are used as lightwave paths for data transfer and one wavelength is used as a lightwave path for signaling path multiplexing of signaling channels. I do. This transmission device transfers the signaling channel via another lightwave path without multiplexing the signaling channel on the lightwave path for main signal data transfer.

The transmission apparatus shown in FIG. 7 is different from the transmission apparatus shown in FIG.
And a signaling channel demultiplexing unit 1120, and a signaling demultiplexing unit 1070-1
073 is deleted. In FIG. 7, those provided with the same reference numerals as those shown in FIG.
These are the same functional blocks as those in FIG. Here, focusing on differences from the transmission apparatus shown in FIG. 6, FIG.
Will be described.

Signaling path demultiplexing sections 1110-1
113 denotes input / output ports 501-i and 502-
i, 501- (i + 1), 502- (i + 2) and the wavelength division multiplexing / demultiplexing unit 10
It is inserted between 10 and 1013, and the input / output port 5
The WDM signals from the signal paths 01 and 502 are separated into a signaling path transfer lightwave path and a data transfer lightwave path, the signaling path transfer lightwave path is transferred to the signaling channel demultiplexer 1120, and the data transfer lightwave path is set to a wavelength. The data is transferred to the demultiplexers 1110 to 1113. The signaling path multiplexing / demultiplexing units 1110 to 1113 include a light path for signaling path transfer from the signaling channel multiplexing / demultiplexing unit 1120 and the wavelength multiplexing / demultiplexing units 1010 to 1113.
The lightwave path for data transfer from 013 is multiplexed and transferred to the input / output ports 501 and 502.

Signaling channel demultiplexing section 1120
Separates the signaling paths from the signaling path demultiplexing units 1110 to 1113 into signaling channels, and terminates the wavelength group signaling processing unit 10
50, 1051. On the other hand, the signaling channel of the wavelength group that is not terminated and the signaling processing unit 1
The signaling channels from 050 and 1051 are multiplexed to form a signaling path, converted to a lightwave path, and transferred to the signaling path demultiplexers 1110 to 1113.

In the transmission apparatus shown in FIG. 7, signaling transfer is performed on a light wave path different from the light wave path for data transfer. Therefore, in the network shown in FIG. 8A having the same configuration as that shown in FIG. 1A, the lightwave path 1210 is set between the transmission devices 520 and 530 on the bidirectional fiber 501, and the lightwave path 1210 The lightwave path 1210 of the same wavelength group as the transmission device 510, 54 on the bidirectional fiber 502 via the transmission device 520, 530.
Even if it is set to 0, that is, even if the setting sections of the lightwave paths of the same wavelength group partially overlap, the signaling channels 1230-1 to 1230-4 as shown in FIG. Is set, the path switching information of the wavelength group can be exchanged between the transmission apparatuses 510, 520, 530, and 540. As a result, FIG.
In the transmission device of FIG. 7, when a signaling channel is multiplexed on a lightwave path, the lightwave paths of the same wavelength group can be set in the same section or only a completely different section, whereas in the transmission apparatus of FIG. The restriction is eliminated, and a more flexible light wave path can be set.

As described above, the transmission apparatus shown in FIG. 7 can realize the above-described fault recovery method according to the present invention, and separates the lightwave path for signaling transfer from the lightwave path for data transfer, thereby achieving WDM transmission. The light path setting of the network can be made flexible.

[0067]

As described above, according to the fault recovery method of the present invention, the fault is detected by the terminal transmission device for each lightwave path, and the fault recovery process operates for each wavelength group of the lightwave path. There is an effect that even if a lightwave path of a wavelength suffers a failure, the lightwave path can be recovered from the failure. In addition, since the protection light path is switched independently at the path end for each light wave path, the transmission distance of the light wave path after recovery from the failure is shorter than the method of bypassing the failure point, and there is no need to limit the network scale. There is.

Further, since a fault is independently detected at the light wave path end for each light wave path, the method is more accurate than a method of detecting a fault based on the light amount of a WDM signal, and signal deterioration can be detected as a fault. Therefore, it is possible to efficiently recover from the failure.

According to the present invention, when a certain lightwave path suffers a fault, information relating to the setting or determination of the backup lightwave path is notified to the transmission device terminating the lightwave path of the same wavelength group through which the backup lightwave path passes. for that reason,
When the notification is not received, that is, in a normal state without a failure, the ET can be accommodated by using the network resources of the backup lightwave path, and the effect that the network can be used efficiently also occurs. In addition, when a failure of a certain working lightwave path occurs, a plurality of backup lightwave path candidates are set, and a backup lightwave path can be selected by using a result of monitoring the state of the backup lightwave path candidate. A suitable backup lightwave path can be selected. Similarly, in the present invention, since a backup lightwave path can be finally selected by using a result of setting a plurality of backup lightwave path candidates and monitoring the state of the backup lightwave path candidates, it is not necessary to specify a failure point. Can recover from a failure.

In general, in a method in which a fault is detected and recovered only by the transmission device at the end of the lightwave path, if the setting sections of the lightwave paths of the same wavelength group partially overlap, it may not be possible to identify the faulty part. For this reason, if a specific backup lightwave path is determined and then the failure is recovered, the recovery may not be possible. However, according to the present invention, since a plurality of backup lightwave path candidates are set and a backup lightwave path is uniquely determined without specifying a failure location, it is possible to always recover from a failure.

According to the present invention, the lightwave path for data transfer and the lightwave path for signaling channel transfer can be separated. Accordingly, even if the setting sections of a plurality of lightwave paths of the same wavelength group partially overlap, information exchange using a signaling channel can be performed, so that lightwave path setting of a network can be flexibly performed, and The bit rate and the signal format of the lightwave path of the group can be freely set.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a physical / lightwave path of a WDM transmission network for explaining a failure recovery method according to a preferred embodiment of the present invention.

FIG. 2 is a failure recovery sequence diagram of a wavelength group of a wavelength λ _i in the failure recovery method shown in FIG. 1;

FIG. 3 is a diagram showing a temporal change of a lightwave path network of a wavelength group of a wavelength λ _i when a fault is recovered.

FIG. 4 is a failure recovery sequence diagram of a wavelength group of wavelength λ _j in the failure recovery method shown in FIG. 1;

FIG. 5 is a diagram illustrating a temporal change of a lightwave path network in a wavelength group of a wavelength λ _j when a fault is recovered.

6 is a block diagram showing an example of a configuration of a transmission device used in the failure recovery method shown in FIG.

7 is a block diagram showing another example of the configuration of the transmission device used in the failure recovery method shown in FIG.

FIG. 8 is a network diagram of a lightwave path network for data transfer and a lightwave path for signaling channel or signaling path transfer.

FIG. 9 is a configuration diagram of a conventional transmission device used for a WDM transmission network.

FIG. 10 shows a physical / physical system for explaining a conventional failure recovery method.
It is a figure showing an example of a lightwave path network.

FIG. 11 is a failure recovery sequence diagram for explaining a conventional failure recovery method in a WDM transmission network.

FIG. 12 is a diagram showing a fault recovery sequence for explaining a problem of the conventional fault recovery method when two lightwave paths are set in the WDM transmission network and a lightwave path network after the fault recovery.

[Explanation of symbols]

101, 102, 201-i, 201- (i + 1), 202-i,
202- (i + 1), 501-i, 501- (i + 1), 502-i, 5
02- (i + 1), 1001 to 1004 I / O ports 110, 111 Line switches 120, 121, 1070 to 1073 Signaling multiplexing / demultiplexing units 130, 131, 1010 to 1013 Wavelength multiplexing / demultiplexing units 140, 141 Failure detecting units 150, 1050 , 1051 Signaling processing unit 160, 1030, 1031 Switch control unit 201-1 to 201-5, 202-1 to 202-5, 501-1 to
501-5, 502-1 to 502-5 bidirectional fiber 210, 220, 230, 240, 250, 510, 5
20,530,540,550 Transmission device 260,401,402,560-N, 561-N, 570
-N, 571-N, 561-R, 561-RM, 571-R, 57
1-RM lightwave path 310-1 to 310-4, 311-1, 320-1, 321-1 to
321-4, 410-1, 410-2, 411-1, 411-2,
420-1, 421-1, 430-1, 431-1, 440-1, 441-1, 441-2 Line route switching request information 330-1 to 330-4, 331-1, 340-1, 341 -1 to
341-4, 450-1, 450-2, 451-1, 451-2,
460-1, 460-2, 461-1, 461-2 Line path switching response information 610, 611, 620, 621 Spare lightwave path setting request information 630, 631, 640, 641 Spare lightwave path setting response information 650, 651, 660, 661 Preliminary lightwave path selection result information 670, 671, 680, 681 Preliminary lightwave path selection result response information 1020 to 1023 ADM 1040, 1041 Lightwave path switch 1060 to 1063 Lightwave path termination processing unit 1080 Spare lightwave path selection unit 1090, 1091 Selector / Bridge section 11010-1113 Signaling path demultiplexing section 1120 Signaling channel demultiplexing section

Continuation of front page (56) References JP-A-7-177219 (JP, A) JP-A-4-888738 (JP, A) JP-A-2000-209244 (JP, A) JP-A-9-51332 (JP, A A) Japanese Patent Laid-Open No. 5-292125 (JP, A) Japanese Patent Laid-Open No. 5-227213 (JP, A) Kazuo Takagi et al., Realization of BWPSR fault recovery method by detecting optical path edge fault, 1999 IEICE General Conference , Japan, The Institute of Electronics, Information and Communication Engineers, March 8, 1999, B-8-34, 311 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14 / 00-14/08 H04L 12/26

Claims (23)

(57) [Claims] 1. A communication path (hereinafter, referred to as a lightwave path) comprising a plurality of wavelength division multiplex transmission apparatuses (hereinafter, referred to as transmission apparatuses) and including arbitrary physical wavelengths in arbitrary sections between the transmission apparatuses. ) Can be set bidirectionally, and a lightwave path (hereinafter referred to as a backup lightwave) used as a detour when a failure occurs in the working lightwave path with respect to a normally used lightwave path (hereinafter referred to as a working lightwave path) In a method for recovering from a failure in a wavelength division multiplexing transmission network in which one or more paths are predetermined, a transmission apparatus terminating at least one lightwave path can monitor a signal state received using the lightwave path. In addition, a lightwave path termination processing function that can detect a failure from the monitoring result, and one or a plurality of backup lightwave paths can be set simultaneously when a failure of the working lightwave path is detected. And a bridge function for simultaneously transferring the same signal to a plurality of protection lightwave paths for a certain working lightwave path, and selecting one protection lightwave path from the plurality of protection lightwave paths for a certain working lightwave path. A possible transmission function, and when a failure occurs in a certain working lightwave path, the working lightwave path in which the failure has occurred is regarded as a troubled lightwave path, and the transmission device at the end detecting the failure in the troubled lightwave path (Hereinafter, referred to as a failure detection transmission device) is connected to a transmission device at the other end of the failure lightwave path (hereinafter, referred to as a failure lightwave path opposite transmission device) by using the lightwave path switching function to use a current lightwave. A plurality of backup lightwave paths for the path are set as candidates, and the same data signal is transmitted to the plurality of backup lightwave paths using the bridging function on the signal transmitting side of the faulty lightwave path. In the fault detection transmission device and the fault lightwave path opposite transmission device, the plurality of standby lightwave paths are monitored using the lightwave path termination processing function, and based on the result of the monitoring, the set standby lightwave is set. One or a plurality of available backup lightwave paths are selected from the paths, and one of the selected backup lightwave paths is determined using the selector function. A failure recovery method characterized by releasing a set backup lightwave path. 2. The working lightwave path is composed entirely of a single physical wavelength, and the backup lightwave path for the working lightwave path is the same as or different from the physical wavelength constituting the working lightwave path. By forming a wavelength group formed by one or more limited physical wavelengths used in the working lightwave path and a plurality of backup lightwave paths to the working lightwave path, the fault lightwave path of the wavelength group unit The failure recovery method according to claim 1, wherein the failure recovery is performed independently. 3. The failure recovery method according to claim 1, wherein the backup lightwave path is provided to the working lightwave path with a different path and / or a different physical wavelength from the working lightwave path. If 4. A preliminary light wave path for said fault light wave path when there exist a plurality of or a plurality of preliminary light wave path is set to select one spare optical path among them,
A selection order is set in advance for those backup lightwave paths, and the failure detection transmission device selects one or a plurality of backup lightwave paths for performing failure recovery of the failed lightwave path according to the selection order. Item 4. The failure recovery method according to any one of Items 1 to 3. 5. The method according to claim 1, wherein the selection order is a hop number, a transmission distance,
The failure recovery method according to claim 4, wherein the failure recovery method is set based on one or more parameters selected from the group consisting of network resource efficiency, failure recovery probability, and received data error rate. 6. A communication path composed of a plurality of wavelength division multiplex transmission apparatuses (hereinafter, referred to as transmission apparatuses) and having an arbitrary physical wavelength in an arbitrary section between the transmission apparatuses (hereinafter, referred to as an optical path). ) Can be set bidirectionally, and a lightwave path (hereinafter referred to as a backup lightwave) used as a detour when a failure occurs in the working lightwave path with respect to a normally used lightwave path (hereinafter referred to as a working lightwave path) the path) is predetermined or higher one, the signaling channel to transfer control information to switch to the spare optical path from the working light wave path and setting and releasing information of a desired preliminary optical path when a failure, or before
In the failure recovery method in a wavelength division multiplexing transmission network in which a signaling path multiplexing the signaling channel is set between the transmission devices, a transmission device terminating at least one lightwave path is received using the lightwave path. A lightwave path terminating function capable of monitoring a signal state and detecting a failure from the monitoring result; and a lightwave path switching function capable of simultaneously setting one or a plurality of backup lightwave paths when a failure of the working lightwave path is detected. A bridge function for simultaneously transferring the same signal to a plurality of protection lightwave paths for a certain working lightwave path, a selector function for selecting one protection lightwave path from the plurality of protection lightwave paths for a certain working lightwave path, Control information for setting / selecting a backup lightwave path is exchanged using the signaling channel. And a signaling processing function for switching, when a failure occurs in a certain working lightwave path, the working lightwave path in which the failure has occurred is regarded as a troubled lightwave path, and the trouble in the troubled lightwave path is treated as the lightwave path termination processing. A transmission device at the end detected using the function (hereinafter referred to as a failure detection transmission device) selects one or more backup lightwave path candidates that can be set from the plurality of backup lightwave paths, and selects another one of the failure lightwave paths. An end transmission device (hereinafter, referred to as a faulty lightwave path opposite transmission device) is notified of backup lightwave path setting request information including the standby lightwave path candidate information selected as configurable, and the faulty lightwave path opposite transmission device is notified. When receiving the backup lightwave path setting request information, the standby lightwave path candidate is extracted and the notified backup lightwave path candidate is set to a receivable state. The backup light path setting response information including the information is transmitted, and the failure detection transmission device that has received the protection light path setting response information extracts the reception setting information of the protection light path from the protection light path setting response information and receives the information. The same signal branched to the backup lightwave path whose setting has been confirmed is transmitted, and the reception state of the plurality of backup lightwave paths is monitored to select one or more available backup lightwave paths, and the available backup lightwave path is selected. The backup lightwave path selection result information including the backup lightwave path information is transmitted to each other, and when the failure detection transmission device and the failure lightwave path opposite transmission device receive the backup lightwave path selection result information, usable backup lightwave path information is extracted. Then, by comparing the spare lightwave path information with the spare lightwave path information selected by the own transmission apparatus, a spare lightwave path to be used is determined from a plurality of available spare lightwave paths. When the failure detection transmission device and the failure lightwave path opposite transmission device receive the backup lightwave path selection result response information, the failure detection transmission device and the failure lightwave path opposing transmission device receive the backup lightwave path selection result response information including the determined protection lightwave path information. A failure recovery method comprising: maintaining the determined backup lightwave path setting; and releasing the set backup lightwave path other than the determined backup lightwave path. If 7. Preliminary optical path for said fault light wave path when there exist a plurality of or a plurality of preliminary light wave path is set to select one spare optical path among them,
The selection order is set in advance for these backup lightwave paths, and the fault detection transmission device selects one or more backup lightwave paths for performing fault recovery of the faulty lightwave path according to the selection order. Item 7. The failure recovery method according to Item 6. 8. The selection order includes a hop number, a transmission distance,
The failure recovery method according to claim 7, wherein the failure recovery method is set based on one or more parameters selected from the group consisting of network resource efficiency, failure recovery probability, and received data error rate. 9. The wavelength division multiplexing network, wherein a network resource of a backup lightwave path for a certain working lightwave path is shared with a network resource of a protection lightwave path of another working lightwave path , and a failure in the certain working lightwave path. The failure detection transmission device or the failure lightwave path opposite transmission device that has detected the protection lightwave path setting request information, the protection lightwave path setting response information, the protection lightwave path selection result information, and the protection lightwave path selection result response information To the transmission device at the end of the working lightwave path having a backup lightwave path that shares network resources with the selected backup lightwave path (hereinafter referred to as a backup lightwave path shared transmission device). When the device receives the protection light path setting information, the device shares network resources with the notified protection light path. The backup lightwave path is deleted from the backup lightwave path candidates of the working lightwave path, and further, if the target lightwave path setting response information cannot set the target lightwave path, or the target lightwave path selection result information If the backup lightwave path is not selected, or if the backup lightwave path of interest is not determined in the backup lightwave path selection response information, the backup lightwave path sharing network resources with the backup lightwave path is The fault recovery method according to any one of claims 6 to 8, wherein the current lightwave path is added to the backup lightwave path candidate again. 10. The wavelength division multiplexing network, wherein a network resource of a backup lightwave path for a certain working lightwave path is shared with a network resource of a protection lightwave path of another working lightwave path , and a failure in the certain working lightwave path. The failure detection transmission device or the failure lightwave path opposite transmission device that has detected the protection lightwave path setting request information, the protection lightwave path setting response information, the protection lightwave path selection result information, and the protection lightwave path selection result response information To the transmission device at the end of the working lightwave path having a backup lightwave path that shares network resources with the selected backup lightwave path (hereinafter referred to as a backup lightwave path shared transmission device). When the device receives the backup lightwave path setting information, the device shares network resources with the notified backup lightwave path. The backup lightwave path is deleted from the backup lightwave path candidates of the working lightwave path and the order of the backup lightwave path candidates is dynamically changed.Furthermore, the target lightwave path setting response information cannot set the target backup lightwave path. If, or if the target backup lightwave path was not selected in the backup lightwave path selection result information, or if the target backup lightwave path was not determined in the backup lightwave path selection response information,
A backup lightwave path sharing network resources with the backup lightwave path is added again to the backup lightwave path candidate of the working lightwave path, and the order of the backup lightwave path is dynamically changed,
The failure recovery method according to claim 7. 11. The wavelength division multiplexing transmission network sets a lightwave path (hereinafter referred to as an ET lightwave path) for the purpose of any additional or supplementary use of network resources normally assigned to the backup lightwave path. The fault detection transmission device or the fault lightwave path opposite transmission device can be used as a network resource for performing the protection lightwave path setting request information, the protection lightwave path setting response information, and the protection lightpath selection result information. The backup lightwave path selection result response information is transmitted to the transmission device at the end of the ET lightwave path that has set up the ET lightwave path using the network resources of the selected backup lightwave path (hereinafter, referred to as “transmission device”).
ET lightwave path terminal transmission device), and when the ET lightwave path terminal transmission device receives the backup lightwave path setting request information, the ET
The use of the lightwave path is stopped to set up a backup lightwave path, the backup lightwave path selection response information is received, the determined backup lightwave path information is extracted, and the backup lightwave path whose use has been stopped is determined as the backup lightwave path. If the network resource of the ET lightwave path is used, the suspension of the use of the ET lightwave path is continued, and if the network resource of the backup lightwave path in which the ET lightwave path whose use has been stopped is not used is used, the ET lightwave path is used. The failure recovery method according to claim 6, wherein use of the device can be resumed. 12. The working lightwave path is all constituted by a single physical wavelength, and a backup lightwave path for the working lightwave path is a single physical wavelength which is the same as or different from the physical wavelength constituting the working lightwave path. By forming a wavelength group formed by one or more limited physical wavelengths used in the working lightwave path and a plurality of backup lightwave paths to the working lightwave path, the fault lightwave path in the wavelength group unit The failure recovery method according to any one of claims 6 to 11, wherein the failure recovery is performed independently. 13. The method according to claim 6, wherein the backup lightwave path is provided to the working lightwave path with a different path and / or a different physical wavelength from the working lightwave path.
The failure recovery method described in the section. 14. A backup lightwave path on a path to which the backup lightwave path setting request information, the backup lightwave path setting response information, the backup lightwave path selection result information, and the backup lightwave path selection result response information are respectively transferred. 14. The failure recovery method according to any one of claims 6 to 13, wherein the failure recovery method has only information on candidates or has information on all backup lightwave path candidates irrespective of a route to be forwarded. 15. A backup lightwave path candidate on a route to which the backup lightwave path setting request information, the backup lightwave path setting response information, the backup lightwave path selection result information, and the backup lightwave path selection result response information are respectively transferred. The transmission device transmitting the backup lightwave path setting request information or the protection lightwave path selection result information, the protection lightwave path setting response information or the protection lightwave path selection result response information is transmitted to a predetermined 15. The failure recovery method according to claim 14, wherein when the reception is not performed within the time, the backup lightwave path candidate is deleted from the candidates. 16. A plurality of wavelength division multiplex transmission devices (hereinafter, referred to as “wavelength division multiplex transmission devices”
A communication channel (hereinafter, referred to as a transmission device) including an arbitrary physical wavelength in an arbitrary section between the transmission devices.
Lightwave path) can be set bidirectionally, and a lightwave path (hereinafter referred to as a working lightwave path) used as a detour when a fault occurs in the working lightwave path (hereinafter referred to as a working lightwave path). hereinafter, the preliminary light wave and path) is predetermined or higher one, the signaling channel to transfer control information to switch from a desired preliminary light wave path setting and release of information and working light wave path when a failure to the backup optical path, or, ,
In a transmission device used in a wavelength division multiplexing transmission network in which a signaling path multiplexing the signaling channel is set between the transmission devices, a wavelength division multiplexed signal is separated into lightwave paths for each wavelength, and the separated lightwave path A wavelength multiplexing / demultiplexing unit that multiplexes the transmitted lightwave path and the lightwave path newly inserted from the own transmission device, and the lightwave path separated by the wavelength multiplexing / demultiplexing unit is transferred.
The lightwave path terminated by the own transmission device is taken into the own transmission device, the lightwave path not terminated by the own transmission device is transferred to the wavelength division multiplexing / demultiplexing unit, and the lightwave path generated by the own transmission device is further subjected to wavelength demultiplexing. An ADM unit for transferring the lightwave path to a unit, a lightwave path switch unit for switching a lightwave path captured and transferred by the ADM unit, and a lightwave path generated by the own transmission device; and a transfer from the lightwave path switch unit. A lightwave path termination processing unit for detecting a failure of the lightwave path terminated by the own transmission device and terminating the lightwave path generated by the own transmission device, and a lightwave path transferred from the lightwave path termination processing unit A signaling multiplexing / demultiplexing unit for multiplexing a signaling channel from the transmission channel into a signaling channel or an optical path generated by the own transmission apparatus; and a data of an optical path starting from the own transmission apparatus. A signal signal from one of the signaling multiplexing / demultiplexing units or the data signal, and simultaneously transfers the signal to a plurality of the signaling multiplexing / demultiplexing units, and one of the lightwave path data signals transferred from the plurality of signaling multiplexing / demultiplexing units. And a selector / bridge unit for selecting and taking in the own transmission device, receiving failure information from the lightwave path termination processing unit, and information transferred from another transmission device by a signaling channel separated by the signaling demultiplexing unit. And generating or processing information related to setting or selection of a backup lightwave path, notifying the information to a signaling demultiplexing unit, transferring the information to another transmission device through the signaling channel, and transmitting the ADM unit and the lightwave path switching unit. And its own transmission device by controlling the selector / bridge unit. A signaling processing unit that changes the route and / or wavelength of the lightwave path that passes through, thereby setting a backup lightwave path of the faulty lightwave path and switching from the working lightwave path to the backup lightwave path; Upon receiving the path selection request, one or more backup lightwave path candidates are selected, and when a protection lightwave path selection decision request including a plurality of backup lightwave path candidate information is received from the signaling processing unit, one of the plurality of backup lightwave paths is selected. And a backup lightwave path selection unit that notifies the signaling processing unit of the selection result. 17. A plurality of wavelength division multiplex transmission apparatuses (hereinafter, referred to as a plurality of wavelength division multiplex transmission apparatuses).
A communication channel (hereinafter, referred to as a transmission device) including an arbitrary physical wavelength in an arbitrary section between the transmission devices.
Lightwave path) can be set bidirectionally, and a lightwave path (hereinafter referred to as a working lightwave path) used as a detour when a fault occurs in the working lightwave path (hereinafter referred to as a working lightwave path). hereinafter, the preliminary light wave and path) is predetermined or higher one, the signaling channel to transfer control information to switch from a desired preliminary light wave path setting and release of information and working light wave path when a failure to the backup optical path, or, ,
In a transmission device used in a wavelength division multiplexing transmission network in which a signaling path multiplexing the signaling channel is set between the transmission devices, a wavelength division multiplexed signal is separated into lightwave paths for each wavelength, and the separated lightwave path A wavelength division multiplexing / demultiplexing unit that multiplexes the transmitted light wave path and the light wave path newly inserted from the own transmission device, and converts the inputted wavelength multiplexed signal into a light wave path for signaling path transfer and a light wave path for data transfer. The separated lightwave path for data transfer is transferred as an input signal to the wavelength division multiplexing / demultiplexing unit, and the lightwave path for signaling path transfer generated by the own transmission apparatus and the WDM signal transferred from the wavelength division multiplexing / demultiplexing unit are separated. A signaling path demultiplexing unit for multiplexing, receiving failure information from the lightwave path termination processing unit, The optical path for signaling path transfer transferred from the signal demultiplexing unit is terminated, a signaling channel to be processed is separated from the signaling path, a signaling channel not to be processed is transmitted, and the optical path path for signaling path transfer and the A signaling path terminating unit for remultiplexing the signaling channel and the signaling channel on which the signaling process has been performed in the own transmission apparatus to generate an optical path for signaling path transfer, and thereafter transferring the signal path to a signaling path demultiplexing unit; The lightwave path separated by the wavelength division multiplexer is transferred,
The lightwave path terminated by the own transmission device is taken into the own transmission device, the lightwave path not terminated by the own transmission device is transferred to the wavelength division multiplexing / demultiplexing unit, and the lightwave path generated by the own transmission device is further subjected to wavelength demultiplexing. An ADM unit for transferring the lightwave path to a unit, a lightwave path switch unit for switching a lightwave path captured and transferred by the ADM unit, and a lightwave path generated by the own transmission device; and a transfer from the lightwave path switch unit. A lightwave path termination processing unit for detecting a failure of the lightwave path terminated by the own transmission device and terminating the lightwave path generated by the own transmission device, and a data signal of the lightwave path starting from the own transmission device Is transferred to one of the signaling multiplexing / demultiplexing units or the plurality of signaling multiplexing / demultiplexing units at the same time by branching the data signal. A selector / bridge unit that selects one of the data signals of the lightwave path and takes it into its own transmission device; and a failure information from the lightwave path termination processing unit and another signaling channel separated by the signaling path demultiplexing unit. Receiving information transferred from the transmission device,
The result of generating or terminating or processing the information on the backup lightwave path setting or selection is transferred to a signaling path demultiplexing unit through a signaling channel and notified to another transmission device, and the ADM unit, the lightwave path switch unit, and By controlling the selector / bridge unit, the route and / or wavelength of the lightwave path passing through the own transmission device is changed, thereby setting the backup lightwave path of the faulty lightwave path and switching from the working lightwave path to the backup lightwave path. A signaling processing unit, upon receiving a backup lightwave path selection request from the signaling processing unit, selecting one or more backup lightwave path candidates, and determining a backup lightwave path selection including a plurality of backup lightwave path candidate information from the signaling processing unit. Upon receiving the request, it selects one from multiple backup lightwave paths and returns the selected result. A transmission device comprising: a backup lightwave path selection unit that notifies a signaling processing unit. 18. The working lightwave path is composed entirely of a single physical wavelength, and a backup lightwave path for the working lightwave path is the same as or different from the physical wavelength constituting the working lightwave path. A wavelength group is formed by one or a plurality of limited physical wavelengths used in a working lightwave path and a plurality of protection lightwave paths for the working lightwave path, wherein the signaling processing unit terminates in its own transmission device. The transmission device according to claim 16, wherein the transmission device is arranged for each group, and performs failure recovery for each wavelength group. 19. The working lightwave path is all constituted by a single physical wavelength, and the backup lightwave path for the working lightwave path is the same as or different from the physical wavelength constituting the working lightwave path. A wavelength group is formed by one or a plurality of limited physical wavelengths used in the working lightwave path and the plurality of protection lightwave paths for the protection lightwave path. And having the path information, setting the selection order of the backup lightwave path based on at least one parameter selected from the group consisting of the number of hops, the transmission distance, the use efficiency of network resources, and the probability of failure recovery, 19. The one or more backup lightwave paths that are higher in the ranking in response to the backup lightwave path selection request of the unit. Transmission apparatus according to item 1. 20. The backup lightwave path selector, based on a predetermined order from a plurality of backup lightwave path candidates, in response to a backup lightwave path selection determination request notified from the signaling processing unit. The transmission device according to claim 16, wherein the transmission device is determined to be one. 21. When the set number of backup lightwave path candidates is larger than the number of lightwave path termination processing units, the lightwave path switch causes the signaling processing unit to perform the A
The connection between the DM unit and the lightwave path termination processing unit is sequentially connected in a time-divided manner, so that the state of each of the plurality of backup lightwave path candidates can be monitored by one lightwave path termination processing unit. Item 18. The transmission device according to item 16 or 17. 22. The wavelength division multiplexing network according to claim 16, wherein network resources of a backup lightwave path for a certain working lightwave path are shared with network resources of a protection lightwave path of another working lightwave path. The transmission device according to claim 1. 23. The wavelength division multiplexing transmission network sets a lightwave path (hereinafter referred to as an ET lightwave path) for the purpose of arbitrarily adding or supplementarily using network resources allocated to the backup lightwave path. The signaling processing unit controls the ADM unit, the lightwave path switch unit, and the selector / bridge unit to control the ADM unit, the lightwave path switch unit, and the selector / bridge unit.
The transmission device according to any one of claims 16 to 21, wherein a wavelength is changed, thereby stopping or restarting use of the ET lightwave path.