JPH07250356A - Optical path network configuration method - Google Patents

Abstract

PURPOSE:To reduce a setting time and the number of wavelengths by setting an optical path so as to minimize the number of accommodated optical paths of an optical transmission line and reducing the number of multiple wavelengths by 2nd setting in the optical communication network where wavelength multiplex optical cross connectors are connected by the optical transmission line. CONSTITUTION:The optical communication network in which wavelength multiplex cross connectors 1-9 having plural nodes are interconnected by corresponding optical transmission lines 11-22 is controlled by an optical path controller 41. For example, an optical path 31 or the like of the shortest path minimizing the number of accommodated optical paths accommodated in the transmission lines 11-22 is set as a current path between a start point 33 and an end point 34. Similarly, an optical path 32 being a bypass with a few standby optical path accommodation number is set as a standby path to each of the transmission lines 11, 12, 15, 20. Furthermore, as to optical paths maximizing the number of multiplexed wavelengths, a current path and a standby path are set again to decrease the number of wavelengths. The setting time is reduced by the method with less setting number and the number of multiplexed wavelengths is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication network in which a large number of nodes are connected by wavelength-multiplexed optical transmission lines.
The present invention relates to a method for setting an optical path set up between two nodes in a network as rationally as possible. Particularly, it relates to a technique for reducing the number of wavelengths required in an optical path network.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 9 is a diagram showing the configuration of an optical path network. 10 and 11 are flowcharts showing a procedure for setting an optical path in the conventional example. The procedure shown in FIG. 10 is described in a patent application filed by the same applicant as the present application, Japanese Patent Application No. 5-289492 (unpublished at the time of application of the present application). This is an optical path setting method that determines the paths by using the shortest path search so that the number of the optical paths accommodated in is equal.

With this optical path setting method, it is possible to reduce the number of wavelengths required in an optical path network that allocates wavelengths for each optical transmission line when failure switching is not considered. A procedure for setting the optical path 31 in the optical path network of FIG. 9 using this conventional optical path setting method will be described below. However, since this method is a method of setting the working optical path, the setting of the spare optical path 32 in FIG. 9 is not performed.

A request for connection of the optical path 31 is issued by the optical path control device 4
When 1 is input, the route of the optical path 31 is set in the control unit 42. First, optical path 3 to set
The positional information between the end points 33 and 34 of No. 1 is input to the optical path control device 41 (S1). As data to be used when performing the route search, the route data of the already set optical path is read from the optical path data storage device 43 and loaded into the control unit 42. Based on this data, each optical transmission line 1
The number of optical paths passing through 1 to 22 is calculated, and this value is set as the distance in each of the optical transmission lines 11 to 22 (S2). Using the distances of the respective optical transmission lines 11 to 22 obtained in S2, the shortest route connecting the optical cross-connect devices 1 and 9 accommodating the termination points 33 and 34 of the optical path 31 is searched (S).
3). The resulting route passes through the optical transmission lines 11, 12, 15, 20 having a small number of accommodated paths, and a route that evenly accommodates the optical paths is searched for in all the optical transmission lines 11 to 22. In this example, the optical transmission lines 11, 12,
It is assumed that the route passing through 15 and 20 has been selected. This path is used as the path of the optical path 31 and the optical path 31 is set (S4). After the setting of the optical paths 31 is completed, it is determined whether the setting of all the optical paths is completed (S5). As a result, if the paths of all the optical paths are determined, the setting of the optical paths is completed, and if there are optical paths that have not been set yet, S3 to S5 are repeated until all the paths of those optical paths are set. To do.

By the above optical path setting procedure, the setting of the optical path network for reducing the number of wavelengths required in the network can be performed by using the shortest route search when failure switching is not considered.

Next, a method of accommodating an optical path in the case of considering failure switching will be described with reference to the block diagram of the optical path network in FIG. 9 and the flowchart showing the procedure for setting the optical path in FIG. The method of FIG. 11 is a method described in another patent application, Japanese Patent Application No. 5-336330 (unpublished at the time of filing of this application) related to the same applicant as this application, and is a route candidate for the working and backup optical paths. This is a method of searching all of, and randomly selecting from them, and setting an optical path. Fault switching in the network
For example, if the optical transmission line 11 fails, the working optical path 31 passing through the optical transmission line 11 will fail, and in order to restore this optical path 31, the failed optical path 31 is replaced with a spare optical path 32. Need to switch. The conventional example can be applied to a system in which the same wavelength is assigned to the working and protection optical paths.

In the following description, a case where the working optical path 31 and the corresponding spare optical path 32 are set will be described. However, the processing that is first performed in the optical path control device 41 is the same as the processing in the optical path setting procedure that uses the shortest path search method described at the beginning, so description thereof will be omitted.

The wavelength number assigned to the optical path 31 is initialized. For example, here, initialization is performed by setting the wavelength identification number to "1" (S11). Next, the optical cross-connect devices 1 and 9 accommodating the termination points 33 and 34 of the optical path 31 can be connected, and the optical transmission paths 11 to 22 in which the wavelength "1" is not assigned to other optical paths can be connected. All route candidates are obtained (S12). As a result, it is determined whether or not there is a route candidate for the optical path (S1).
3). At this time, if a route candidate exists, the following process (S15) is performed. If it does not exist, the process of S14 is performed.

First, the processing after S14 will be described. If the wavelength is assigned to another optical path and there is no assignable wavelength, no route candidate exists. Therefore, it is necessary to prepare another wavelength as the wavelength to be assigned to the optical path and search for the route. In order to change the wavelength assigned to the optical path, the wavelength number used for the route search is increased by "1" (S14). The processing of S12 and S13 is performed using this new wavelength, and the processing is repeated until the route candidate of the working optical path can be searched.

If a route candidate exists, one route candidate is selected from these (S15). The selected route is assumed to be the route of the working optical path, and a route candidate for the spare optical path to which the same wavelength as the working optical path is assigned is searched (S16). As a result, if there is a route candidate, one of them is selected and set as a backup optical path (S19).
If there is no route candidate or if there is another active route candidate, one of the route candidates that has not been selected is selected and the processes of S15 to S17 are performed. If there is no route candidate for the working optical path, the process proceeds to S14 and S12.
The procedure from S17 to S17 is repeated. By the above procedure, the paths of the working optical path 31 and the spare optical path 32 and the wavelengths assigned to them are determined.

[0011]

[Problems to be Solved by the Invention] Japanese Patent Application No. 5-28949
In the method of setting the working optical path using the shortest path shown in No. 2, the working optical path can be evenly accommodated in the optical path network. On the other hand, the spare optical path is not always used all the time, but is used to restore the cut optical path when a failure occurs in the optical transmission line or the like. For this reason, if an attempt is made to accommodate a spare optical path using this method, all the spare optical paths will be accommodated evenly in the network, so a spare optical path that is switched when a certain failure occurs. The paths may be concentrated on a specific optical transmission line. In this case, the number of required wavelengths in the optical transmission line where the spare optical paths are concentrated increases. As a result,
When the accommodation design including the backup optical path is performed, there is a problem that the working and backup optical paths cannot be reasonably accommodated in the optical path network.

In the method of obtaining and setting all the route candidates for the working and protection optical paths shown in Japanese Patent Application No. 5-336330, all the routes are determined and randomly selected from among them, so that a route capable of accommodating an optical path is selected. In order to rationally set the wavelength assigned to the optical path, it is necessary to repeatedly set the wavelength many times. Therefore, it takes a very long time to accommodate the optical path, and when the network scale becomes large, there is a problem in that some of the optical paths cannot be accommodated due to the problem of calculation time.

The present invention has been made against such a background, and provides an optical path network construction method capable of shortening the time required for accommodation design in the optical path network of the working and protection optical paths. With the goal. An object of the present invention is to provide an optical path network construction method capable of reasonably accommodating an optical path in each optical transmission line. An object of the present invention is to provide an optical path network construction method that reduces the number of multiplexed wavelengths. SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical path network configuration method in which even when a failure occurs in an optical transmission line, optical paths are evenly assigned to each optical transmission line, and the number of multiplexed wavelengths is reduced. It is an object of the present invention to provide an optical path network configuration method that reduces the number of times wavelength conversion is performed from the start point to the end point of a route.

[0014]

According to the present invention, the number of spare optical paths accommodated in an optical transmission line to be used due to a failure is set as the distance of each optical transmission line used when searching for a route of a spare optical path. To use. Furthermore, assuming all optical transmission line failures,
The distance of the optical transmission line is calculated. By performing the shortest route search based on the distance of the optical transmission line, it is possible to reasonably accommodate not only the working optical path but also the protection path in the optical path network. Furthermore, when setting the optical path, the optical path is set by a deterministic method using the shortest path search method or the maximum flow path search method, so that it is possible to reduce the labor required for housing design. Characterize.

That is, the present invention provides a path for connecting nodes in an optical communication network including a plurality of nodes each having an optical cross-connect device using wavelength division multiplexing and a plurality of optical transmission lines connecting these nodes. Is a method of configuring an optical path network for setting.

Here, the feature of the present invention resides in the step of setting the route having the smallest number of optical paths accommodated in the optical transmission line as the current route, and for each optical transmission line. Assuming that a failure has occurred one by one, and setting a detour path that minimizes the number of detour paths accommodated with respect to the working path of each optical transmission path at the time of failure as a spare path of the working path. , The step of resetting the working and protection paths so that the number of wavelengths required to configure the set working and protection paths is reduced.

It is desirable that the resetting step is executed for one or more optical transmission lines including the optical transmission line having the maximum number of multiplexed wavelengths. It is desirable to set such that the same wavelength is allocated between the start point and the end point of one working or protection path. Alternatively, it is desirable to set the same wavelength for the working and protection paths having the same start point and end point.

[0018]

According to the present invention, when a route search for a backup path is performed,
Since the distances of the optical transmission lines are calculated assuming the failure of all the optical transmission lines and the shortest path is searched, the working and protection optical paths can be reasonably accommodated in the optical path network. Further, when a route is searched, the number of labors required for accommodation setting for searching the route by a decisive method such as the shortest route search method or the maximum flow path search method can be reduced, so that the accommodation design time can be shortened.

Further, since the calculation for wavelength reduction is performed only for the optical transmission line where the number of multiplexed wavelengths is maximum, the calculation time can be shortened while maintaining the effect of wavelength reduction.
The same wavelength can be assigned between the start point and the end point of one working or protection path, or the same wavelength can be assigned for the working and protection paths having the same start point and end point.

The step of resetting is performed for the optical transmission line having the maximum number of multiplexed wavelengths and omitted for the other optical transmission lines, whereby the required number of wavelengths can be reduced and the calculation time can be reduced. It can be shortened.

By making the wavelengths from the start point to the end point of one path the same, wavelength conversion is eliminated and the required number of wavelengths can be reduced. The number of multiplexed wavelengths can be reduced even in the event of a failure.

[0022]

【Example】

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flow chart showing a procedure for setting a working optical path according to the first embodiment of the present invention. FIG. 2 is a diagram showing an optical path accommodation example of the first embodiment of the present invention. FIG. 3 is a flow chart showing the procedure for setting a spare optical path according to the first embodiment of the present invention. FIG. 4 is a flow chart showing a procedure for reducing the number of required wavelengths in the first embodiment of the present invention. See FIG. 9 for the overall configuration of the optical path network.

According to the present invention, as shown in FIG. 9, a plurality of nodes having optical cross-connects 1 to 9 using wavelength division multiplexing and a plurality of optical transmission lines 11 to 2 connecting these nodes.
2 is an optical path network configuration method for setting a path connecting between nodes in an optical communication network including

Here, the feature of the present invention is that the number of optical paths accommodated in the optical transmission lines 11 to 22 is set as a distance, and the optical path having the minimum distance is used as the current optical path. Steps for setting as paths, and each optical transmission line 11 to 11
It is assumed that one failure occurs for each 22 and the number of detour optical paths accommodated in the respective optical transmission paths 11 to 22 for the working optical path at the time of failure is set as a distance, and this distance is minimized. Setting a detour optical path as a spare optical path of the working optical path, and the working and protection so that the number of wavelengths required to configure the set working and protection optical paths is reduced. The step of resetting the optical path is included in the control unit 42.
The step of resetting is performed for the optical transmission line having the maximum number of multiplexed wavelengths.

Next, the operation of the first embodiment of the present invention will be described. As shown in FIG. 9, the optical cross-connect devices 1 to 9 perform cross-connect switching of optical paths. The wavelength-multiplexed optical transmission lines 11 to 22 connect the optical cross-connect devices 1 to 9. The optical path 31 is a working optical path, and the optical path 32 is a backup optical path to which the optical path 31 is switched when a failure occurs. Optical paths 31 and 32 connect between termination points 33 and 34. The optical path control device 41 controls the optical path. The control unit 42 designs the accommodation of the optical path. The optical path data storage device 43 records the optical path data and the assigned wavelength data set by the control unit 42. The control signal link 44 transmits a control signal between the optical path control device 41 and each optical cross-connect device 1-9.

FIG. 1 shows a method of assigning a wavelength to an optical path for each optical transmission line, that is, an optical path system in which the wavelength assigned to an optical path can be changed for each optical transmission line.
This is an optical path accommodation design method characterized in that a route search for the working optical path 31 and a route search for the backup optical path 32 are performed using different weighting functions. Here, a case where the working optical path 31 and the backup optical path 32 are set in the optical path network of FIG. 9 will be described. However, the spare optical path 32 is the optical cross-connect device 1 through which the active optical path 31 passes.
The condition that the setting is performed using a route that does not pass 9 is added.

To the optical path control device 41, the positions of the optical cross connect devices 1 and 9 accommodating the termination points 33 and 34 of the optical paths 31 and 32 to be set are input. Based on this, in the control unit 42, the two optical cross-connect devices 1,
The optical paths 31 and 32 are set by using a path connecting 9 and reducing the number of wavelengths required in the network. The optical path accommodation design method performed by the control unit 42 will be described below.

First, the procedure for setting the working optical path 31 will be described with reference to the flowchart of FIG. However, the procedure for setting the working optical path 31 is the same as the method for setting using the conventional shortest path. In order to set the optical path 31, information on other optical paths is required, so the control unit 42
Reads data from another optical path from the optical path data storage device 43. Based on this data, each optical transmission line 11-22
The number of working optical paths accommodated therein is determined, and the obtained value is set as the distance between the optical transmission lines 11 to 22 (S21). If there are multiple optical paths to be set, the setting order must be determined. The optical transmission lines 11 to 2 passing through the paths connecting the terminal points 33 and 34 of the optical paths 31 and 32.
It is necessary to find the number of passing optical transmission lines when the number of 2 is the minimum (this minimum value of the number of passing transmission lines is hereinafter referred to as the minimum hop number). The minimum hop numbers of the respective optical paths are compared, and the setting is performed from the one having the largest value (S22). However, in general, when the setting is performed according to this order, the best effect of reducing the required number of wavelengths is obtained, but when the setting is performed in another order, for example, even if the setting is performed in any order, it is the best. Results may be obtained.

The shortest route is searched based on the distances of the respective optical transmission lines 11 to 22 obtained in S21, and this shortest route is set as the route of the working optical path 31 (S23). By increasing the distance of the optical transmission lines 11, 12, 15, 20 through which the determined route passes by 1, the respective optical transmission lines 11, 12, 1 are increased.
The distances of 5 and 20 are updated (S24). For example, in this embodiment, the optical transmission lines 11 and 1 are used as the routes of the working path 31.
It is assumed that a route passing through 2, 15, and 20 has been searched. At this time, the distances of the optical transmission lines 11, 12, 15, 20 are updated by adding "1" to the distances of the optical transmission lines 11, 12, 15, 20. Optical transmission line 11, 1 of S24
After the updating of the distances of 2, 15, and 20 is completed, it is determined whether the setting of all the working optical paths 31 is completed (S2).
5). As a result, if there is a working optical path that has not been set,
The next working optical path is set according to the setting order obtained in S22 (S26). That is, S23 to S25 are repeated to set all the working optical paths. As a result of S25, if all the working optical paths have been set, the setting of the working optical path 31 is completed, and the spare optical path for the newly set working optical path is set.

Next, the procedure for setting the spare optical path 32 will be described with reference to the flowchart of FIG. First, the distances of the optical transmission paths 13, 18, 21, 22 used for the route search of the new spare optical path 32 are obtained using the data of the other spare optical paths read from the optical path data storage device 43. .
First, a certain optical transmission line is selected. However, since the following procedure is performed for all the optical transmission lines 11 to 22, any optical transmission line may be selected (S31). All working optical paths that pass through the selected optical transmission path are searched (S32). The number of spare optical paths accommodated in each optical transmission line of the spare optical paths corresponding to the searched working optical path is obtained (S33). The number of spare optical paths accommodated in each optical transmission line obtained in S33 indicates how much the spare optical path used when the optical transmission line selected in S31 fails is accommodated in each optical transmission line. It is the indicated value. It is determined whether S32 and S33 have been performed for all optical transmission lines (S
34), if there is an unselected optical transmission line, the next optical transmission line is selected (S35), and S32 and S33 are performed.

For example, as shown in FIG. 2, a working optical path A
Has the optical transmission lines 11 and 12 as a route, the spare optical path A has the optical transmission lines 13, 16, 17, and 15 as a route, and the active optical path B has the optical transmission line 12 as a route. A case will be described in which the backup optical path B has an optical path having the optical transmission paths 14, 17, and 15 as routes.
When the optical transmission path 12 is selected in S31, the working optical paths A and B pass, so when the number of spare optical paths accommodated in each optical transmission path is obtained in S32, the optical transmission path 1
7, 15 are "2", the optical transmission lines 13, 14, 16 are "1", and all the other optical transmission lines 18 to 22 are "0". The optical transmission line 11 through which the optical paths A and B pass,
Table 1 shows the results of S31 to S34 for 12 only.

[0032]

[Table 1] It is assumed that the distance of the optical transmission path used for the route setting of the spare optical path is obtained using the number of spare optical paths accommodated calculated from S31 to S35. However, it is assumed that the setting order of the spare optical path is the same as the setting order of the working optical path obtained in S22. In addition, assuming that all the optical transmission paths through which the working optical path passes are out of order, the total number of spare optical paths accommodated in each optical transmission path, which is obtained in all cases, is summed up to determine the path of the spare optical path. The distance of each optical transmission line used for the search is obtained (S36). Here, since the working optical path 31 does not pass through the optical transmission lines 11, 12, 15, and 20, the spare optical signals of the respective transmission lines obtained when the optical transmission lines 11, 12, 15, and 20 fail. Calculate the total number of passes accommodated. The results of this calculation are shown in Table 1. At the end of this table, the total number of spare optical paths accommodated is shown as distance.

In the first embodiment of the present invention, since there is a condition that the spare optical path does not pass through the optical cross-connect device through which the working optical path passes, the spare optical path is connected to the optical cross-connect device through which the working optical path passes. It is necessary to set the distance of the optical transmission line so that the optical transmission line to be selected is not selected. In order to realize this, the distance of the optical transmission line connected to the optical cross-connect device through which the current optical path other than the optical cross-connect device that accommodates the end point of the optical path passes is set to a sufficiently large value, and The optical transmission line is not selected (S37). Here, "1000" is added to the distance of the optical transmission line as a sufficiently large value.
The results are shown in Table 2. In Table 2, the distances of the respective optical transmission lines obtained in S36 are shown together, and the distances of the optical transmission lines used for the shortest path search are shown as the final result.

[0034]

[Table 2] Returning to FIG. 9, the shortest route is searched based on the distance of each optical transmission line obtained in S36 and S37, and the obtained route is set as the route of the spare optical path (S38). Here, the shortest route is the route that passes through the optical transmission lines 13, 18, 21, and 22, and the route length at this time is 2. The obtained route becomes the route of the spare optical path 32.

After setting the paths of the spare optical paths 32, it is judged whether all the spare optical paths have been set (S3).
9). As a result, if there is a spare optical path that has not been set,
The next spare optical path is set by repeating steps S36 to S38 to set the path (S40).

When the setting of all the spare optical paths is completed,
The setting of the working and spare optical paths is completed, and the obtained data is stored in the optical path data storage device 43. Further, the control device 42 assigns a wavelength to an optical path for each optical transmission line. The wavelength allocation at this time may be any allocation method. When the active optical path 31 is actually opened, the optical path control device 41 uses the optical cross-connect devices 1, 2, 3, 6, based on the route data and the wavelength data of the optical path in the optical path data storage device 43. Control signal to 9 Control signal link 4
4 to connect the optical paths 31 and 32.

Although the initial solution was set in the above procedure, effective use of network resources is achieved by resetting the working and protection optical paths and reducing the number of wavelengths required for the network. be able to. However, in the method of reducing the required number of wavelengths, when all the optical paths are reset, the calculation time required for the accommodation design increases due to the repeated calculation. Therefore, some optical paths will be reset. The number of wavelengths required for the network changes depending on the optical transmission line that fails. Therefore, attention is paid only to the failure of the optical transmission line having the maximum required number of wavelengths, and the optical path affected by the failure of the optical transmission line is reset.
The procedure for this reduction will be described with reference to the flowchart shown in FIG.

First, the optical path network is searched for a failure in the optical transmission line that maximizes the required number of wavelengths (S41). Search all active optical paths that pass through this optical transmission line (S4
2). The number of accommodated active optical paths in S32 and S33 is set as the distance of each optical transmission path, and the route of the active optical path is reset by the procedure for searching the shortest path (S43). However, the order of resetting is the same as the order of setting the initial solution. It is determined whether or not the resetting of all the working optical paths found in S42 has been completed (S44). As a result, if there is a working optical path that has not been set, the next working optical path is selected (S45), and the working optical path is reset by the procedure of S43.

After the resetting of all the working optical paths is completed, the spare optical paths corresponding to these are reset. Resetting of the spare optical path is performed in the same order as that of the resetting of the working optical path. First, a spare optical path to be initially set is selected (S46). The distance of the optical transmission path used for resetting is obtained by the procedure of S36 and S37. Based on the obtained distances of the respective optical transmission lines, the shortest route is searched and used as the route of the spare optical path (S47). It is judged whether or not all the spare optical paths have been reset (S48), and if there is an unset spare optical path, the next spare optical path is selected (S48).
49), the spare optical path is reset by the procedure of S47. When the setting of all the spare optical paths is completed, it is confirmed whether the predetermined specified number of repetitions have been performed (S50).
If the specified number of repetitions has not been performed yet, S41
~ S49 is performed again. When the specified number of times is completed, all the processing is completed. For example, in an optical path network with 15 optical cross-connect devices, the required number of wavelengths can be reduced by repeating the specified number of times about 10 times.

As described above, in the first embodiment of the present invention, the distance of the optical transmission line used for the search of the active optical path is set as the accommodation number of the active optical path, and the optical transmission line used for the search of the spare optical path. Since the distance is calculated as the number of spare optical paths that can be accommodated assuming an arbitrary optical transmission line failure, it is possible to reduce the number of wavelengths required for the network. Is possible. further,
In order to carry out the accommodation design by performing the shortest route search,
Compared with the method of searching all the route candidates of the optical path and determining the route, it is possible to reduce the labor required for the accommodation design. That is, it is possible to reduce the calculation time required for housing design. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flow chart showing the wavelength allocation procedure of the second embodiment of the present invention. The second embodiment of the present invention uses the optical path routing method described in the first embodiment of the present invention to perform route setting of the working and protection optical paths, and to the working and protection optical paths for which the routes have been set. This is a housing design method that assigns wavelengths. This accommodation design method allows the case where the assigned wavelengths for the working optical path and the backup optical path are different in the optical path method in which the working optical path and the backup optical path both use the same wavelength between the optical path termination points. It is a housing design method suitable for the switching method. In the present accommodation design method, after obtaining the initial solutions of the working and backup optical path paths obtained from S21 to S26 of FIG. 1 and S31 to S40 of FIG. 3 in the first embodiment of the present invention, S41 of FIG. After S49 is performed to reset the working and protection optical path routes, the following wavelengths are assigned to the obtained working and protection optical path routes. The wavelength allocation procedure will be described below.

First, the wavelength assigned to the optical path is initialized. Here, the wavelength initialization is the number of the assigned wavelength #
Wave is set to "1", and wavelength numbers are assigned in order from the smallest wavelength channel length (S51). However, the numbers assigned to the wavelengths may be in any order. After initializing the wavelengths, the order of the optical paths for wavelength allocation is determined. The sum of the optical transmission paths through which the working and protection optical path paths pass is calculated. The sum of the two is calculated for all the optical paths, and wavelengths are assigned from the optical path having the larger value (S52). Next, the data flag1 and flag2 used for determining whether the wavelength #wave is available are initialized (S).
53). That the wavelength #wave can be used here means that the wavelength #wave is not assigned to another optical path, and therefore the wavelength can be assigned to the optical path. However, in the spare optical path, it is possible to assign the same wavelength of the same transmission line to a plurality of spare optical paths that do not simultaneously fail when an optical transmission line failure occurs. The wavelength is assumed to be usable. The flag1 is a value assigned to each optical transmission line, and is set to "0" if the wavelength #wave of the optical transmission line is usable, and is set to "1" if it is not usable. flag
1 has the number of the optical transmission line as an argument, so "fla"
g1 [optical transmission line number] ".
Data 2 indicates whether or not the wavelength can be assigned to the spare optical path, and is set to "0" if usable and "1" if usable. The flag 2 has as arguments the optical transmission path through which the working optical path passes and the number of the optical transmission path through which the backup optical path corresponding to the working optical path passing through the working optical path passes. For this reason, it is represented as "flag2 [current transmission optical transmission line number] [optical transmission line number]". For example, the route of the working optical path 31 of FIG. 9 is given by the optical transmission lines 11, 12, 15, and 20, and the route of the corresponding spare optical path 32 is the optical transmission lines 13, 18, and.
It is given at 21, 22. The value of flag2 when a wavelength is assigned to this spare optical path 32 is shown below as an example. The current optical path 31 is the optical transmission line 11, 1
Since the spare optical path 32 passes through the optical transmission line 13, the flag 2 [11] [13] =
1, flag2 [12] [13] = 1, flag2 [1
5] [13] = 1 and flag2 [20] [13] = 1 are given. Fla over the entire path of the spare optical path
If you insert the data of g2, flag2 [11] [18]
= 1, flag [12] [18] = 1, flag2 [1
5] [18] = 1, flag2 [20] [18] = 1 and flag2 [11] [21] = 1, flag [12]
[21] = 1, flag2 [15] [21] = 1, fl
ag2 [20] [21] = 1 and flag2 [11] [2
2] = 1, flag [12] [22] = 1, flag2
[15] [22] = 1, flag2 [20] [22] =
It becomes 1. The initialization of flag1 and flag2 is performed by setting the values of all data to "0" (S5).
3).

After flag1 and flag2 have been initialized, wavelength allocation for all optical paths is performed according to the wavelength allocation order. First, it is determined whether or not the wavelength has already been assigned to the working optical path (S54). If so, wavelength allocation is performed for the spare optical path (S
58-S61). If the wavelength has not been assigned yet, it is determined whether the wavelength #wave can be assigned to the route of the active optical path 31 (S55). This decision is
Flags of routes 11, 12, 15, 20 of the current optical path
If all the values of 1 are "0", it is determined that the allocation is possible, and if there is at least one "1", #wave is determined to be non-allocatable. If it is determined that allocation is possible, the wavelength #wave is allocated to the working optical path (S56). In addition, fla
The values of g1 and flag2 are updated (S57). this is,
Flag1 [11] = 1, flag1 [12] = with respect to flag1 of the optical transmission line that the current optical path 31 passes through.
1, flag1 [15] = 1, flag1 [20] = 1
By doing so, the update is performed. Furthermore, the current optical path 3
Since the wavelength is assigned to 1, it cannot be used even for the spare optical path 32. Therefore, flag2 [11]
[A1] = 1, flag2 [12] [a1] = 1, fl
ag2 [15] [a1] = 1, flag2 [20] [a
1] = 1 (a1 indicates all optical transmission line numbers).

After the wavelength is assigned to the working optical path, the wavelength is assigned to the spare optical path corresponding to the working optical path. First, it is determined whether or not wavelengths have already been assigned to this spare optical path (S58). If it has been assigned, the wavelength assignment for this optical path is terminated and the process proceeds to S62. Wavelength # if not assigned
It is determined whether the wave can be allocated to the spare optical path (S59). This determination is made by checking the value of flag2 for the paths of the working and protection optical paths. In the determination for the spare optical path 32, the working optical path route passes through the optical transmission lines 11, 12, 15, 20 and the spare optical path 32 route is determined as the optical transmission lines 13, 18, 21, 22.
Because it is passing through the flag2 [11] [13], f
flag2 [11] [18], flag2 [11] [2
1], flag2 [11] [22], and flag [1
2] [13], flag2 [12] [18], flag
2 [12] [21], flag2 [12] [22],
flag2 [15] [13], flag2 [15] [1
8], flag2 [15] [21], flag2 [1
5] [22] and flag2 [20] [13], fla
g2 [20] [18], flag2 [20] [21],
When all the values of flag2 [20] [22] are "0", it is determined that the allocation is possible, and in other cases, it is determined that the allocation is impossible. When it is determined that the allocation is impossible, S62
Move to.

If it is determined that the wavelength can be assigned, the wavelength #wave is assigned to the spare optical path 32 (S60).
Further, the value of flag1 and the value of flag2 are updated (S61). This is flag1 [11] = 1, fla
g1 [12] = 1, flag1 [15] = 1, flag
1 [20] = 1 and flag2 [11] [13] =
1, flag2 [11] [18] = 1, flag2 [1
1] [21] = 1, flag2 [11] [22] = 1,
flag2 [12] [13] = 1, flag2 [12]
[18] = 1, flag2 [12] [21] = 1, fl
ag2 [12] [22] = 1, flag2 [15] [1
3] = 1, flag 2 [15] [18] = 1, flag
2 [15] [21] = 1, flag2 [15] [22]
= 1, flag2 [20] [13] = 1, flag2
[20] [18] = 1, flag2 [20] [21] =
1, flag2 [20] [22] = 1, then fl
Update of ag1 and flag2 is performed. Spare optical path 3
After the wavelength allocation for No. 2 is completed, it is checked whether the allocation determination of wavelength #wave has been performed for all the optical paths (S6).
2). As a result, if there is an optical path for which the wavelength allocation determination has not yet been performed, S54 to S61 are performed for the next optical path in accordance with the allocation order that was initially set.

If the wavelength allocation is determined for all the optical paths, it is checked whether the wavelength is allocated to all the optical paths (S63). If there is an optical path for which wavelength allocation is not performed, add “1” to the wavelength number #wave and start from S53.
S63 is performed. When wavelength allocation has been performed for all optical paths, this wavelength allocation is terminated.

As a result of performing this wavelength allocation method, the maximum number of allocated wavelengths becomes equal to the number of wavelengths required for the network.
In order to reduce the required number of wavelengths, the optical path route is reset, and wavelengths are assigned to the route for which the reset is performed, thereby searching for a route in which the required number of wavelengths can be reduced. For example, in an optical path network having 15 optical cross-connect devices, the required number of wavelengths can be reduced by resetting the route about 10 times.

As described above, in the present embodiment, the required number of wavelengths is reduced even for the optical path of the system in which one wavelength is allocated between the optical path termination points for the working optical path and the backup optical path. Furthermore, by reducing the labor required for path setting, it is possible to perform accommodation setting with a shorter calculation time than in the past. (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a diagram showing an optical path for explaining the third embodiment of the present invention. FIG. 7 is a flow chart showing the procedure for setting the initial solution of the optical path according to the third embodiment of the present invention. The third embodiment of the present invention is a method for designing the accommodation of optical paths in the optical path system in which the same wavelength is allocated between the optical path termination points for the working and standby optical paths. In addition, a failure switching method that assumes a single transmission path failure shall be applied.

As shown in FIG. 7, the order of setting the optical paths is such that the minimum hop numbers of the respective optical paths are compared and the optical path is set from the largest one (S71). Before setting the optical path, the wavelength assigned to the optical path is initialized. Here, the initialization of the wavelength is performed by setting the wavelength number #wave assigned to the optical path to "1" (S7).
2). Next, the data capa and flag used for determining whether the wavelength #wave is available are initialized (S73). capa is data used when setting the current optical path, and is the wavelength # in the optical transmission line.
When wave is available, a constant is given to capa, and when it is not available, "0" is given to capa. For example, if the physical network scale of about 15 optical cross-connect devices is available, the value of capa to be given may be about "5". The flag is data used when setting a spare optical path. If the wavelength #wave is usable for the spare optical path, "0" is given, and if not usable, "1" is given.

For example, in the example of the optical path shown in FIG. 6, in the optical transmission line through which the working optical path A passes, capa [1
6] = 0, capa [19] = 0, and capa [18] = in the optical transmission line through which the spare optical path A passes.
0, capa [21] = 0, and the values of capa in other optical transmission paths are all “5”. Also, the flag
Regarding the optical path of the working optical path, flag [1
6] = 1 and flag [19] = 1, and the flag values in the other optical transmission lines are all “0”. The reason why the flag value is determined only from the route of the working optical path is shown below. In order to avoid wavelength collision, a plurality of working optical paths assigned the same wavelength are not accommodated in the same optical transmission line. That is, when a single optical transmission line failure occurs, the optical paths to which the same wavelength is assigned are not simultaneously disconnected due to the failure. So, for example,
When the optical transmission line 16 fails, only the working optical path A is disconnected, and other spare optical paths are not used at this time.

On the contrary, when the other working optical path is disconnected, the working optical path A is not affected by the failure, and the spare optical path B is not used. That is, the spare optical paths can share the same wavelength on the same optical transmission line. On the other hand, the wavelength assigned to the working optical path is always used. That is, since the wavelength assigned to the working optical path cannot be assigned to the spare optical path, the value of the flag is determined by the route of the working optical path.

First, a working optical path is set using capa. Using the value of capa as the capacity of each optical transmission line, a maximum flow path search is performed to search for a route of the current optical path (S7).
4). However, when performing the maximum flow path search, the search is performed with the unit of the flow rate being "1". After the route search, it is determined whether a route candidate exists (S75). When a route candidate exists, a route search for a backup optical path is continuously performed. In order to perform the route setting of the spare optical path by using the shortest route search, f
The distance of each optical transmission line is calculated from the lag value and the current optical path route obtained in S74 (S76). At this time, since a route passing through the unusable optical transmission line is not searched for as a spare optical path, a sufficiently large value is given to the distance of the unusable optical transmission line. As a result, when the shortest route search is performed, the unusable route is not selected.
For example, in a physical network having 15 optical cross-connect devices, about 10 ³ is given as the unusable optical transmission path distance. On the other hand, "1" is given to the usable distance of the optical transmission line.

Next, a distance of the same size is given to the optical transmission line through which the route candidate of the current optical path passes, and the distance of the optical transmission line is set so that the route using the optical transmission line is not selected. . Further, here, in order to add a condition that the working optical path and the protection optical path do not pass through the same optical cross-connect device, the end point of the optical path is accommodated in the optical cross-connect device through which the working optical path passes. The distance of the optical transmission line connected to devices other than the optical cross-connect device is set to a large value to some extent, and this optical transmission line is not selected as a route. As described above, the distances of the optical transmission lines are set for all working optical paths (S76). Based on the set distance of the optical transmission line, the shortest route is searched for as the route of the spare optical path (S77). As a result, it is determined whether there is a spare optical path route (S78). If there is a spare optical path route, there are multiple working optical path candidates, and the one with the smallest sum of the optical transmission paths through which the working and spare optical paths pass is selected as the working and protection path. Select as an optical path.
Further, the wavelength #wave is set as the wavelength to be assigned to the working and standby optical paths, and the route of the optical path and the assigned wavelength are determined (S79). The wavelength allocation data capa and flag are updated based on the determined working and protection optical path data (S80). After the setting of this optical path is completed, it is determined whether the allocation of wavelength #wave has been attempted for all the optical paths for which the setting has not been completed (S81). If there is an optical path that does not try to allocate the wavelength #wave in the determination of S81, one unconfigured optical path is selected according to the optical path setting order determined in S71 (S82).
The steps S74 to S81 are performed to set the optical path. S7
When it is determined that the setting of the optical paths at the wavelength #wave has been attempted for all the optical paths as a result of the determination of 1, it is determined whether the setting of all the optical paths is completed (S83). As a result, if the setting of all the optical paths is completed, the setting of the initial solution is completed. Wavelength # if there is an unconfigured optical path
The value of wave is increased by "1" (S84), and S73 to S
The procedure of 83 is repeated. The above procedure is used to complete the setting of the initial solutions for the working and protection optical paths.

A procedure for further reducing the number of wavelengths required for the network will be described with reference to FIG. FIG. 8 is a flowchart showing a procedure for reducing the number of required wavelengths in the third embodiment of the present invention. First, the wavelength #wave is set to "1" (S91). Next, all optical paths to which the wavelength #wave is assigned are searched (S92). It is checked whether both the working and protection optical paths to which this wavelength #wave is assigned can be set using other wavelengths (S93). As a result, when it is determined that another wavelength can be assigned, it is determined whether another wavelength can be assigned to all the optical paths searched for in S92 (S95). As a result, if there is an optical path that has not been examined yet, the operation moves to the next optical path (S96), and the steps S93 to S95 are performed. As a result of S95, if all the optical paths to which the wavelength #wave is assigned are assigned to other wavelengths, it means that the wavelength #wave is not assigned to any optical path, and the number of wavelengths required for the network is set. One wavelength can be reduced (S99). If it becomes impossible for the optical path to which the wavelength #wave is allocated in S94 to allocate another wavelength, then it is determined whether or not all optical paths have been attempted to be allocated to another wavelength (S9).
8). As a result, if all optical paths have not been tried yet, the value of wavelength #wave is increased by "1" (S9
9), the procedure of S93 to S99 is repeated. As a result of trying allocation of other wavelengths to all the optical paths in the determination of S98, if it is impossible to reallocate to any other wavelength at any wavelength, it is impossible to further reduce the wavelength. (S100). In this case, the procedure for reducing the required number of wavelengths is completed.

As described above, the present invention sets the working optical path by using the maximum flow path search for the working and the spare,
In order to set up a spare optical path using the shortest path search,
The calculation time required for the accommodation design can be shortened as compared with the case where all the route candidates are searched and the optical path is set. Furthermore, since the working and protection routes are set and the wavelengths are assigned at the same time, the wavelength can be reduced by a lesser procedure than the conventional method of separately determining the protection and work routes.

[0055]

As described above, according to the present invention,
Since the route search in the optical path network is performed by using different weighting functions between the working optical path and the backup optical path, it is possible to construct an optical path network that reduces the number of wavelength division multiplexing in the optical path network. Furthermore, since the accommodation design of the optical path is performed by the discovery method using the generally known shortest path search method and the maximum flow path search method, the labor required for the accommodation design of this optical path is reduced, that is, the calculation time is reduced. It can be shortened.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for setting a working optical path according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of accommodating an optical path according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a procedure for setting a backup optical path according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a procedure for reducing the number of required wavelengths according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a wavelength allocation procedure according to the second embodiment of the present invention.

FIG. 6 is a diagram showing an optical path for explaining a third embodiment of the present invention.

FIG. 7 is a flowchart showing a procedure for setting an initial solution of an optical path according to the third embodiment of the present invention.

FIG. 8 is a flowchart showing a procedure for reducing the number of required wavelengths in the third embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an optical path network.

FIG. 10 is a flowchart showing a procedure for setting an optical path in a conventional example.

FIG. 11 is a flowchart showing a procedure for setting an optical path in a conventional example.

[Explanation of symbols]

 1 to 9 optical cross-connect device 11 to 22 optical transmission line 31 working optical path 32 backup optical path 33, 34 termination point 41 optical path control device 42 control unit 43 optical path data storage device 44 control signal link

Claims (4)

[Claims] 1. A path for connecting between nodes in an optical communication network including a plurality of nodes having an optical cross-connect device using wavelength division multiplexing and a plurality of optical transmission lines connecting these nodes is set. In the optical path network configuration method, a step of setting a path having a minimum number of optical paths accommodated in the optical transmission path as an active path, and a failure occurring at one position for each optical transmission path Assuming that, a step of setting a detour route that minimizes the number of detour routes accommodated with respect to the working route of each optical transmission line at the time of failure as a spare route of the working route, And a step of resetting the working and protection paths so that the number of wavelengths required to configure the path is reduced. 2. The optical path network configuring method according to claim 1, wherein the re-setting step is executed for one or more optical transmission lines including an optical transmission line having a maximum number of multiplexed wavelengths. 3. The optical path network constructing method according to claim 1, wherein the same wavelength is set between the start point and the end point of one working or protection route. 4. The method of constructing an optical path network according to claim 1, wherein setting is made so that the same wavelength is assigned to working and protection paths having the same start point and end point.