JP3161675B2 - Optical path setting method for WDM optical communication network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an optical communication network in which a number of nodes are connected by a wavelength division multiplexing optical transmission line. In particular, the present invention relates to a method for setting an optical path set between two nodes as reasonably as possible in a network. For more information,
Reduce the total number of optical lines required in the optical path network,
The present invention relates to a technology for reducing the size of an optical cross-connect device.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a conventional optical path network configuration, and FIG. 5 is a flowchart showing a conventional procedure for setting an optical path. Here, the route is determined using the shortest route search so that the number of optical paths accommodated in each optical transmission line is equal to the route of the optical path to be set, and the start and end points of the set route are determined. An optical path setting method for allocating an arbitrary wavelength to each optical transmission line between them will be described.

In the conventional example shown in FIG. 4, each optical transmission line is constituted by one optical line, and the maximum number of wavelengths multiplexed on the optical line is an arbitrary value.

The procedure shown in FIG. 5 will be described with reference to FIG. The optical path control device 61 includes an optical path 41 to be set.
When the end point data and the set number are input, the control unit 62 sets the path of the optical path. Therefore, first, the position information between the optical path terminating devices 21 to 26 where the optical paths 41 to 46 to be set are terminated is input to the optical path control device 61 (step S51).

[0005] In the control unit 62 in the optical path control device 61,
The setting priority is calculated for a plurality of optical path setting requests (step S52). In the example shown in FIG.
Is determined to be the first path to be set. Further, the control unit 62 reads, from the optical path data storage device 63, the path data of the optical path that has been already set as data to be used when searching for the path of the optical path 43, and based on this data, The number of optical paths passing through the optical transmission lines 31 to 37 is calculated.
(Step S53). Subsequently, each of the optical transmission lines 31 to 37 determined in this step is used.
The shortest path is searched for the nodes 1 to 6 that accommodate the optical path terminating devices 21 and 25 as the terminal points of the optical path 43 by using the distances (step S54). In the example illustrated in FIG. 4, it is assumed that a path passing through the optical transmission paths 31 and 34 is selected as a path of the optical path 43 so that the optical path is not biased to a specific optical transmission path. When the selection of the route is completed, the optical path control device 51 sends a signal to the optical cross-connect devices 11 to 16 via the control signal link 54, and sets the optical path 43 according to the selected route (step S5).
5).

After the setting of the optical paths 43 is completed, it is determined whether the setting of all the optical paths is completed (step S5).
6). As a result, if all optical path routes can be determined,
When the setting of the optical path is completed, and there is a path that has not been set yet, according to the setting priority determined in step S52, the procedure of steps S53 to S56 is repeated until all the paths of the optical path are set. . In the example shown in FIG. 4, the path of the optical path 41 passes through the optical transmission path 31, and the path of the optical path 42 is the optical transmission paths 31 and 32.
The optical transmission path 3 is used as a path that passes through
It is assumed that a route passing through the optical transmission lines 36 and 37 is set as a route passing through the optical paths 45, 36, and 37, a route passing through the optical transmission line 36 as a route of the optical path 45, and a route passing through the optical path 46.

A wavelength is arbitrarily assigned to each of the passing optical transmission lines between the start and end points of the set optical paths 41 to 46 (step S57). In the example shown in FIG.
By preparing the wavelength, an optical path network including the optical paths 41 to 46 can be configured.

[0008] By the above-described optical path setting procedure, it is possible to set an optical path network for reducing the number of wavelengths required in the network.

[0009]

As described above, the conventional optical path setting method efficiently reduces the required number of wavelengths by equally allocating a plurality of optical paths to each optical transmission line in the network. We were able to. That is, the conventional optical path setting method is to reduce the number of optical paths in the optical transmission line accommodating the most optical paths.

However, in a network in which the number of nodes accommodating the optical cross-connect device is large, or in a network in which the demand for the optical path between the nodes has increased, the accommodation path in the optical transmission line accommodating the optical path to the maximum is inevitable. There is a problem that the number increases and it is necessary to prepare a large number of wavelengths that can be used to configure an optical path network.

In the current optical technology, it is difficult to secure a large number of usable wavelengths in a network in consideration of transmission characteristics, wavelength accuracy, and other restrictions. When the number of usable wavelengths is limited to a relatively small number, it is necessary to configure each optical transmission line with a plurality of optical lines in order to accommodate many optical paths in the network.

In the setting of an optical path in a network in which the number of wavelengths is limited and each optical transmission line is composed of a plurality of optical lines, when the number of paths accommodated in the optical transmission line is an integral multiple of the number of wavelengths, the use of the optical line Efficiency is maximized, transmission path costs are reduced, and as a result, the number of paths of the optical cross-connect device is also reduced, so that an increase in node costs can be suppressed. However, the conventional optical path setting method does not necessarily perform a path search such that the number of optical paths in the optical transmission path is an integral multiple of the number of wavelengths. There is a problem that it is difficult to configure an optical path network.

Further, in the conventional optical path setting method, when using in an optical path method in which wavelength conversion is not performed by the optical cross-connect device, that is, a method in which the same wavelength is allocated between the start point and the end point of the optical path, each optical path is used. The wavelength assigned to the path was one arbitrary wavelength. For this reason, there is no limitation on the wavelengths assigned to the optical paths distributed from the optical cross-connect device to the optical path terminating device in each node, and when many identical wavelengths are assigned to the optical paths, the optical cross-connect device There is a problem that a large number of optical lines connecting between the optical cross-connect device and the optical path terminating device are required, and the scale of the optical cross-connect device is increased.

[0014] The present invention solves the above-mentioned problems, and even if the number of wavelengths that can be prepared in a network is relatively small, it is possible to reduce the accommodating efficiency of an optical transmission line from a plurality of optical lines and to provide a necessary optical line. To provide an optical path setting method for a wavelength-division multiplexing optical communication network by which an optical path network can be constructed economically by reducing the total number of optical paths as much as possible and at the same time efficiently reducing the scale of the optical cross-connect device. Aim.

[0015]

An optical path setting method for a wavelength division multiplexing optical communication network according to the present invention includes an optical cross-connect device for switching connection of an optical path and an optical path terminating device for terminating the optical path. In an optical path setting method of a wavelength division multiplexing optical communication network for setting a path connecting nodes in a wavelength division multiplexing optical communication network in which a plurality of nodes are each connected by an optical transmission line constituted by a plurality of optical lines, An initial optical path network is set, an initial setting step of calculating the total number of optical lines required for the initial optical path network, and a remainder obtained by dividing the number of accommodated paths by the number of multiplexable wavelengths for each optical transmission line, In an optical transmission line where the remainder is a value other than 0, the reciprocal of the remainder is used as the transmission line distance of the optical transmission line, and in the optical transmission line where the remainder is 0, the number of paths accommodated in the optical transmission line is the Transmission path distance as transmission path distance A calculating step, a path searching step of searching for an optical transmission path whose remainder takes a minimum value other than 0, and searching for an optical path path that passes through the searched optical transmission path at most times; A resetting step of resetting one with the shortest distance based on the transmission path distance calculated in the transmission path distance calculation step and obtaining the total number of optical lines required in the optical path network; and a resetting optical path network. Comparing the total number of optical lines required for the optical path network with the total number of optical lines required for the optical path network before resetting, and adopting an optical path network having a smaller total number of optical lines, and determining the resetting step. Steps are repeated for all the optical path paths searched in the path search step.

The optical path network obtained by this method can be used as a new initial optical path network, and the same method can be repeated a predetermined number of times.

As a wavelength allocation procedure for allocating wavelengths to the optical path network obtained by the above method, the optical path in the optical path network is divided into a plurality of layers so that the same optical transmission line is not shared in the same layer. A layer dividing step for dividing, a wavelength allocating step of rearranging the order of each layer to periodically assign multiplexable wavelengths, and an optical cross-connect device in each node in an optical path network in which wavelengths are allocated to optical path paths The number of routes for calculating the total number of routes, the wavelength assignment step and the total number of routes calculation step are repeated a predetermined number of times to determine a wavelength assignment that minimizes the sum of the number of routes. Steps.

This wavelength assignment procedure can be repeated a predetermined number of times.

[0019]

A path is set so as to connect the nodes with the shortest distance for all paths to be set, and an optical path is set so that the number of optical lines in the optical transmission line is reduced for some of the set paths. Reset the path. Specifically, an optical path network is set according to the combination of optical transmission paths and the wavelength of the optical signal transmitted in the optical transmission path, and based on the remainder obtained by dividing the number of optical paths accommodated in the optical transmission path by the number of wavelengths. Then, the shortest optical path is reset so that the number of optical paths in the optical transmission path becomes an integral multiple of the number of wavelengths. As a result, a path with a relatively small number of hops can be set while preferentially selecting an optical transmission line with low accommodation efficiency, and an optical path network with a reduced number of optical lines accommodated in each optical transmission line can be rationalized. It becomes possible to configure it.

In order to assign a wavelength to each optical path of the set optical path network, it is desirable to assign one wavelength from the start point to the end point of each optical path. In this way, it is possible to suppress an increase in the number of optical lines for accommodating the optical paths distributed from the optical cross-connect device to the optical path terminating device in the node. In such wavelength assignment, by assigning a constraint to the assigned wavelength for each optical path route, the wavelength to be assigned to the optical path route can be optimized.

[0021]

FIG. 1 is a block diagram showing a wavelength division multiplexing optical communication network embodying the present invention and its optical path network, and FIG. 2 is a flowchart showing a procedure for setting an optical path. Here, an example is shown in which the number of wavelengths that can be multiplexed in an optical line is two, and each optical transmission line is composed of a plurality of optical lines.

The wavelength division multiplexing optical communication network shown in FIG. 1 includes a plurality of nodes 1 to 6, each of which has an optical cross connect device 11 to 16 for switching connection of an optical path and an optical path terminating device 21 for terminating the optical path. To 26 are provided. Node 1
6 are connected by optical transmission lines 31 to 37. These optical transmission lines 31 to 37 have a plurality of optical lines (in FIG. 1, two optical lines 51 and 52 of the optical transmission line 31, an optical transmission line 31). 32, one optical line 54 of the optical transmission line 33, one optical line 54 of the optical transmission line 34, two optical lines 56 and 57 of the optical transmission line 36, and an optical transmission line. 37, one optical line 58
Only shown) are accommodated. Further, the optical transmission paths 31 to 3
An optical path control device 61 is provided for setting an optical path by controlling the combination of the optical signals 7 and the wavelength of the optical signal transmitted in the optical transmission paths 31 to 37. The optical path control device 61 includes a control unit 62 and an optical path data storage device 63, and controls the respective optical cross-connect devices 11 to 16 of the nodes 1 to 6 via control signal links.

When an optical path setting request is input, the control section 62 of the optical path control device 61 configures an initial optical path network by some method and stores the route data of each optical path in the optical path data storage device 63. It is stored (step S1). As a method of configuring an initial optical path network, for example, step S in which the wavelength assignment procedure is removed from the optical path setting method shown in FIG.
The procedure from 51 to S56 may be used, or another method may be used.

Subsequently, the control unit 62 calculates the number of optical paths accommodated in each optical transmission line, and based on the number of wavelengths that can be multiplexed in each optical transmission line, an optical line required for each optical transmission line. The number is calculated, and the sum is stored in the optical path data storage device as the minimum value of the total number of optical lines (step S2). In the example shown in FIG. 1, since the wavelength multiplexing is set to 2, two optical lines 51, one optical line 52, one optical line 53, and five optical lines 5
4 accommodates one optical path, one optical path 55, one optical path 56, and two optical paths 57, and optical transmission paths 31-37.
It is assumed that the total number of optical lines in the inside is eight.

Next, the control unit 62 determines, for each optical transmission line,
The remainder obtained by dividing the accommodation path by the number of wavelength multiplexes is calculated. The reciprocal of the remainder is obtained for an optical transmission line whose remainder is not zero, and the number of optical paths accommodated in the optical transmission line for an optical transmission line whose remainder is zero. Is calculated as the transmission path distance of each optical transmission path, and is transferred to the optical path data storage device (step S3). In the example illustrated in FIG. 1, the remainders of the optical transmission lines 31 to 34, 36, and 37 are all 1 and the transmission line distances are all 1.

Next, the control section 62 searches for an optical transmission line in which the remainder of the number of accommodated paths and the number of multiplexed wavelengths takes a minimum value other than zero (step S4). In the example shown in FIG.
The remainder of the number of accommodated paths and the number of multiplexed wavelengths (= 2) becomes 1 for ~ 34, 36, and 37, which are search targets.

Next, the control section 62 searches the optical paths 41 to 46 initially set in step S1 for an optical path including a plurality of optical transmission paths searched in step S4 (step S5). . In the example illustrated in FIG. 1, it is assumed that the optical path 43 including the two optical transmission paths 31 and 34 in the searched optical transmission paths is searched.

Next, the control unit 62 searches for the shortest path based on the transmission path distance of each optical transmission path calculated in step S3, and resets the path of the optical path searched in step S5 (step S6). . In the example shown in FIG.
Is the optical path 4 of the path passing through the optical transmission paths 33 and 36.
It is reset as 3 '.

Next, the control unit 62 updates the data on the number of paths accommodated in each optical transmission line each time one optical path searched in step S5 is reset, and considers the number of wavelength division multiplexes. The number of optical lines required for the optical transmission line is determined, and the total number is stored in the optical path data storage device (step S7). FIG.
In the example shown in (1), the number of paths accommodated in each optical transmission path is 2 for the optical transmission path 31, 1 for the optical transmission path 32, 2 for the optical transmission path 33, and 2 for the optical transmission path 34 is 0, optical transmission line 35 is 0, optical transmission line 36 is 4, optical transmission line 3
7 becomes 1. As a result, the number of optical lines required for each optical transmission line is as follows: one optical transmission line 31, one optical transmission line 32, one optical transmission line 33, zero optical transmission line 34, 35 is 0
Book, two optical transmission paths 36, one optical transmission path 37,
The total number is six.

The number of paths accommodated in both the optical line 54 in the optical transmission line 33 and the optical line 56 in the optical transmission line 36 is 2, and the path accommodation efficiency is maximized. At the same time, the number of routes of the optical cross-connect device 11 in the node 1 is reduced by 1 because the optical line 52 is deleted, and the number of routes of the optical cross-connect device 12 in the node 2 is reduced by the optical lines 52 and 55. Therefore, the number of routes of the optical cross-connect device 15 in the node 5 is reduced by 1 because the optical line 55 is deleted, thereby reducing the scale of each cross-connect device.

Next, the control section 62 determines whether or not the total number of optical lines has been reduced by the resetting in step S6 as compared with the minimum value (step S8). If the total number of optical lines is reduced or equal, the transmission line distance data of each optical transmission line is updated based on the minimum value of the total number of optical lines and the data of the reset path (step S9). In the example shown in FIG. 1, since the total number of optical lines is reduced from eight to six,
The transmission path distance is updated based on the route of the optical path 43 '. If the total number of optical lines increases due to the resetting, the route of the optical path is returned to the route before the resetting, and the data on the number of paths accommodated in the optical transmission line through which the optical path passes and the data on the number of necessary optical lines are used. (Step S10).

Next, the control unit 62 determines whether there is an optical path that has been searched in step S5 but has not been reset, and if such an optical path exists, the process returns to step S6 and returns to step S6. The setting is performed, and if it does not exist, the following procedure is executed (step S11). In the example shown in FIG. 1, since only the optical path 43 has been searched as a resetting candidate in step S5, the process proceeds to the next step.

The control unit 62 determines whether or not the procedure of steps S3 to S11 has been repeated an arbitrary specified number of times (= N). If the specified number of times has been reached, the route setting is terminated. Return (step S12). In the example shown in FIG. 1, since N = 1, the setting is completed.

As described above, by reducing the number of optical lines included in each of the optical transmission lines 31 to 37, the number of routes of the optical cross-connect device can be reduced as a result. Here, the optical paths 41 to 46 can be configured by assigning a wavelength to each optical line, but one wavelength can also be assigned to the same path. In either method, the effect of reducing the number of optical lines and the scale of the optical cross-connect device can be obtained. Hereinafter, a method of assigning one wavelength to the same path will be described.

FIG. 3 is a flowchart showing a procedure of setting an optical path and assigning a wavelength by the control unit 62. In this procedure, steps S1 to S1 described with reference to FIG.
13 (step S31) to execute the optical path 41,
After setting 42, 43 ', and 44 to 46, the wavelength assignment procedure (step 32) is executed, and the termination is determined (step S3).
Perform 2) to complete the setting of the optical path. The wavelength assignment procedure will be described in more detail.

In the wavelength assignment procedure of step S32,
The control unit 62 first uses some procedure to execute the optical path 4
1, 42, 43 'and 44 to 46 are divided into a plurality of groups (step S13). Hereinafter, these groups will be referred to as “layers”. In the division into layers, each optical path belonging to each layer is configured not to share a passing optical transmission line with another optical path in the same layer. At this time,
It is desirable to divide each layer so that the number of optical transmission paths used in each layer is maximized. Here, the optical paths 42 and 46 are in layer # 1, the optical paths 41 and 43 'are in layer # 2, the optical path 44 is in layer # 3,
It is assumed that the optical path 45 is divided into layer # 4.

Next, the control section 62 arbitrarily rearranges the layers # 1 to # 4 (step S41). Here, it is assumed that the layers are rearranged in the order of layer # 2, layer # 1, layer # 3, and layer # 4.

Next, the control unit 62 cyclically assigns wavelength numbers in accordance with the order of the layers rearranged in step S14 (step S15). In this example, since the number of wavelengths is two, the optical paths 41 and 4 of layer # 2
The wavelength λ1 is assigned to the optical paths 42 and 46 of the layer # 2 at 3 ′.
The wavelength λ2, the wavelength λ1 in the optical path 44 of the layer # 3,
The wavelength λ2 is assigned to the optical path in the layer # 4.

Next, the control unit 62 monitors the allocated wavelengths of the optical paths terminated in each of the nodes 1 to 6, determines how many optical paths of each wavelength are terminated for each node, and The number of optical lines required between the optical cross-connect device and the optical path terminating device is calculated (step S16). In this example, λ1 is terminated three times and λ2 is terminated once at node 1, λ1 is terminated once at node 2, λ2 is terminated once at node 3, and λ2 is terminated twice at node 4. Terminate and set λ1 to 2 at node 5.
Λ2 is terminated once, and λ1 is terminated once at the node 6. Since one optical line can accommodate one optical signal of λ1 and one optical signal of λ2, the number of optical lines required between the optical cross-connect device and the optical path termination device at each node is three at node 1. , One at node 2 and one at node 3
The number of nodes is two at node 4, two at node 5, and one at node 6.

Next, the control unit 62 determines the number of optical lines required in the optical transmission line connecting the adjacent nodes in step S15.
Is calculated in the same manner as step S16 based on the assigned wavelength (step S17). In this example, one optical path with an assigned wavelength of λ1 and one λ2 are accommodated in the optical transmission line 31, one λ2 in the optical transmission line 32, and one λ1 in the optical transmission line 33.
In this case, two λ1 and two λ2 are accommodated in the optical transmission line 36, and one λ2 is accommodated in the optical transmission line 37. Therefore, the number of optical lines required in each optical transmission line is two in the optical transmission line 31, one in the optical transmission line 32, two in the optical transmission line 33, two in the optical transmission line 36, and two in the optical transmission line 36. 37 is one.

Next, the controller 62 calculates the number of optical lines required between the optical cross-connect device and the optical path terminating device obtained in step S16 and the number of optical lines required in the optical transmission line obtained in step S17. Based on this, the total number of optical lines required for the optical cross-connect in each node is calculated (step S1).
8). In the example shown in FIG. 1, the total number of routes of the optical cross-connect devices 11 to 16 in each of the nodes 1 to 6 is obtained as follows. First, in node 1, adjacent nodes 2 and 4
Therefore, three optical lines are required for the optical path terminating device 21 and three optical lines are required for the optical path terminating device 21, so that the total number of routes is six. On node 2,
Since two optical paths are required for the adjacent nodes 1, 3, and 5, and one optical path is required for the optical path terminating device 22, the total number of routes is four. In the node 3, one optical path is required for the adjacent nodes 2 and 6, and one optical path is required for the optical path terminating device 23. Therefore, the total number of routes is two. In the node 4, four optical paths are required for the adjacent nodes 1 and 5, and two optical paths are required for the optical path terminating device 24, so that the total number of routes is six.
At node 5, three for adjacent nodes 2, 4 and 6,
Since two optical lines are required for the optical path terminating device 25, the total number of routes is five. At node 6, neighbor node 3
1 and 6 and one optical path for the optical path terminating device 26, the total number of routes is two.

Next, the control unit 62 calculates the total sum of the total number of routes of the optical cross-connect devices in each node obtained in step S14, and compares the sum with a value stored in advance in the optical path data storage device 63. Is performed (step S19). In the example shown in FIG. 1, the total sum of the total number of routes is 25. If the value obtained in step 18 is smaller than the value stored in the optical path data in advance, the control unit 62 updates the value stored in the optical path data storage device 63 and performs the processing in step S15. The wavelength allocation is determined to be in the optimal allocation state, and the allocated wavelength for each optical path is stored (step S20). Here, it is assumed that the value has been updated.

Next, the control section 62 executes steps S14 to S2.
It is determined whether 0 has been repeated an arbitrary specified number of times (= M) (step S21). Here, since M = 1, the wavelength assignment ends.

Note that M = 2 and step S1 is repeated.
If 0 is repeated and the layers are rearranged in the order of layer # 1, layer # 2, layer # 3, and layer # 4, in step S18, the total number of routes of each node becomes 4, 3 at node 2, 2 at node 3, 4 at node 4, 5 at node 5, and 2 at node 6.
In this case, the sum of the total number of routes in step S19 is 2
It becomes 0, the optimum wavelength allocation state is updated, and the average number of routes of each optical cross-connect device is reduced.

Next, the control section 62 executes steps S14 to S2.
After repeating 0 for a specified number of times, the path setting procedure of step 31 and the wavelength assignment procedure of step S32 are performed a specified number of times (=
N) It is determined whether the process has been repeated (step S22). Here, since N = 1, the optical path setting procedure ends, and the optical path is set based on the assigned wavelength data stored in the optical path data storage device 63.

[0046]

As described above, according to the present invention,
When the number of wavelengths that can be prepared for the network is limited, the number of routes of the optical cross-connect device can be reduced efficiently. This makes it possible to reduce the scale of nodes to be prepared in the optical path network and economically accommodate optical paths. When the same wavelength is set for one optical path, there is an advantage that the number of optical lines connecting the optical cross-connect device and the optical path terminating device in the node can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a wavelength division multiplexing optical communication network embodying the present invention and its optical path network.

FIG. 2 is a flowchart illustrating a procedure of setting an optical path.

FIG. 3 is a flowchart showing a procedure for setting an optical path and assigning wavelengths;

FIG. 4 is a diagram showing a conventional optical path network configuration.

FIG. 5 is a flowchart showing a conventional procedure for setting an optical path.

[Explanation of symbols]

 1 to 6 nodes 11 to 16 optical cross-connect device 21 to 26 optical path termination device 31 to 37 optical transmission line 41 to 46, 43 ′ optical path 51 to 58 optical line 61 optical path control device 62 control unit 63 optical path data storage Device 64 control signal link

────────────────────────────────────────────────── ─── Continuation of the front page (56) References Naohide Nagatsu, Yoshiyuki Hamazumi, Kenichi Sato, "Evaluation of Required Number of Wavelengths in Optical Path Network", 1994, IEICE Transactions, Vol. J77-B-1; 12, p. 728-737 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04J 14/00-14/08 H04B 10/00-10/28 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A plurality of nodes each provided with an optical cross-connect device for switching connection of an optical path and an optical path terminating device for terminating the optical path are connected by an optical transmission line each including a plurality of optical lines. In an optical path setting method of a wavelength division multiplexing optical communication network for setting a path connecting nodes in a wavelength division multiplexing optical communication network, an arbitrary initial optical path network is set, and an optical path required for the initial optical path network is set. Initial setting step for calculating the total number (S1, S
2) and calculating a remainder obtained by dividing the number of paths accommodated by the number of multiplexable wavelengths for each optical transmission line, and for an optical transmission line in which this remainder is a value other than 0, the reciprocal of the remainder is calculated as the transmission line of the optical transmission line. A transmission path distance calculating step (S3) in which the number of paths accommodated in the optical transmission path is set as the transmission path distance of the optical transmission path in the optical transmission path in which the remainder is 0; Path searching steps (S4, S5) for searching for an optical transmission path taking the following formula, and searching for an optical path path that passes through the searched optical transmission path at most times: A resetting step (S6, S7) for resetting the shortest distance based on the transmission path distance calculated in the distance calculating step and obtaining the total number of optical lines required in the optical path network; Total number of optical lines required for the network and the optical lines required for the optical path network before resetting Determination step (S8 to S8) in which an optical path network having a smaller total number of optical paths is compared with the total number of optical paths.
S10), wherein the resetting step and the determining step are repeated for all the optical path routes searched in the route searching step. 2. A method for setting an optical path in a wavelength division multiplexing optical communication network in which the method according to claim 1 is repeated a predetermined number of times using the optical path network obtained by the method according to claim 1 as a new initial optical path network. . 3. A wavelength assignment procedure for assigning a wavelength to an optical path network obtained by the method according to claim 1.
The wavelength allocation procedure includes a layer dividing step (S13) of dividing an optical path route in the optical path network into a plurality of layers so that the same optical transmission line is not shared in the same layer. A wavelength allocation step (S14, S15) of periodically rearranging multiplexable wavelengths by rearranging the order of layers, and a route of an optical cross-connect device in each node in an optical path network in which wavelengths are allocated to optical path routes Calculating the total number of routes (S16 to S18), and repeating the wavelength allocation step and the total number of routes calculation step a predetermined number of times, to assign a wavelength that minimizes the total number of routes. Determination step (S
19 to S21). An optical path setting method for a wavelength division multiplexing optical communication network. 4. The method according to claim 3, wherein the wavelength allocation procedure is repeated a predetermined number of times.