JP6874611B2 - Management device and management method - Google Patents

Description

The present invention relates to a management device and a management method for managing an optical network.

With the spread of data centers and mobile devices, traffic in networks continues to increase. Therefore, there is a demand for a method of economically providing a wavelength division multiplexing optical network that realizes a large amount of data transmission.

In the design of a wavelength division multiplexing optical network, when accommodating a requested path, it is determined whether or not a repeater is required in the middle of the path of the path. At this time, the transmission quality of the requested path is estimated.

FIG. 1 shows an example of a wavelength division multiplexing optical network. In this example, an optical branch insertion device (ROADM: Reconfigurable Optical Add-Drop Multiplexer) is mounted on each node. ROADM can branch an optical signal having a specified wavelength from a WDM optical signal according to control by a controller. ROADM can also insert an optical signal into an empty channel of a WDM optical signal. The transmission quality estimator estimates the transmission quality of a path when a path setting request is given.

In the above-mentioned wavelength division multiplexing optical network, when the setting of the wavelength path for transmitting the optical signal between the client X and the client Y is required, the transmission quality estimation device estimates the transmission quality of the wavelength path. In this example, it is assumed that the transmission quality of this wavelength path is lower than a predetermined threshold value. In this case, the transmission quality estimation device determines that a repeater is required in the middle of the path of this wavelength path. In the example shown in FIG. 1, two wavelength paths are set so that the optical signal is reproduced in ROADM # 3.

A network control device has been proposed to improve the estimation accuracy for the signal quality of the wavelength path to be estimated. This network control device estimates the signal quality quantity of the wavelength path to be estimated based on the signal quality quantity of each span in the wavelength path to be estimated (for example, Patent Document 1). Further, a method of estimating OSNR in consideration of the non-linear effect in a wavelength division multiplexing system has been proposed (for example, Non-Patent Document 1). Further, Patent Document 2 describes related techniques.

Japanese Unexamined Patent Publication No. 2017-11506 JP-A-2007-233925

G. Bogliolo et al., Considering Transmission Impairments in RWA Problem: Greedy and Metaheuristic solutions, Proc. OFC 2007

In a wavelength division multiplexing optical network, when the number of wavelength paths multiplexed in an optical fiber increases, the transmission quality of each wavelength path deteriorates due to a non-linear effect, crosstalk, and the like. Therefore, in estimating the transmission quality, it is preferable to consider the number of wavelength paths to be multiplexed in each span on the path of the required wavelength path. However, in order to estimate the number of wavelength paths for each span in advance, it is necessary to predict the demand (request for path setting) from the client. However, it is not easy to accurately predict future demand.

Therefore, in the conventional network design, the transmission quality is estimated so that the error rate becomes equal to or less than a predetermined threshold value even in the worst case. That is, the transmission quality is estimated on the assumption that all wavelength paths are used in all spans. However, with this design method, an excessive margin is set. For example, in a span with a small number of wavelength paths, the transmission quality estimate is lower than the actual transmission quality. Therefore, if the network is designed based on this estimated value, the number of repeaters mounted in the network will be larger than necessary. That is, the cost of constructing a network may increase.

An object of one aspect of the present invention is to provide an apparatus and method for accurately estimating the transmission quality of a wavelength path.

The management device of one aspect of the present invention manages paths in an optical network that transmits wavelength division multiplexing optical signals. This management device is based on a storage unit that stores transmission quality values corresponding to the number of multiplex wavelengths for a transmission section on the path set in the optical network, and the topology of the optical network. A centrality calculation unit that calculates the centrality that indicates how close the transmission section is to the center of the optical network, and a wavelength that is multiplexed in the transmission section based on the centrality calculated by the centrality calculation unit. For the transmission section and the prediction unit that predicts the number of, the transmission quality value corresponding to the number of wavelengths predicted by the prediction unit is acquired from the storage unit, and the transmission of the path is transmitted based on the acquired transmission quality value. It includes an estimation unit that estimates quality.

According to the above aspect, the transmission quality of the wavelength path can be estimated accurately.

It is a figure which shows an example of the wavelength division multiplexing optical network. It is a figure which shows an example of the optical network in which a transmission quality estimation apparatus is used. It is a figure which shows the example of the model for calculating the OSNR of a span. It is a figure explaining the relationship between the topology of an optical network and the wavelength division multiplexing. It is a figure explaining the centrality. It is a figure which shows an example of the transmission quality estimation apparatus which concerns on 1st Embodiment. It is a figure which shows an example of the transmission quality database which concerns on 1st Embodiment. It is a flowchart which shows an example of the preprocessing of transmission quality estimation in 1st Embodiment. It is a flowchart which shows an example of the process of estimating the transmission quality of a wavelength path in 1st Embodiment. It is a figure which shows an example of an optical network. It is a figure which shows an example of the transmission quality estimation apparatus which concerns on 2nd Embodiment. It is a figure which shows an example of the transmission quality database which concerns on 2nd Embodiment. It is a figure which shows an example of an auxiliary database. It is a flowchart which shows an example of the preprocessing of transmission quality estimation in 2nd Embodiment. It is a flowchart (the 1) which shows an example of the process of estimating the transmission quality of a wavelength path in 2nd Embodiment. 2 is a flowchart (No. 2) showing an example of processing for estimating the transmission quality of the wavelength path in the second embodiment. It is a figure which shows an example of the hardware composition of the transmission quality estimation apparatus.

FIG. 2 shows an example of an optical network in which the transmission quality estimation device according to the embodiment of the present invention is used. In the optical network 1 according to the embodiment, a wavelength division multiplexing optical signal (WDM optical signal) is transmitted. Therefore, a WDM transmission device is mounted on each node of the optical network 1. The WDM transmission device is realized by, for example, an optical branch insertion device (ROADM). In this case, ROADM is implemented in each node # A to # F.

The network management system 2 sets a wavelength path corresponding to the demand given by the client. The demand contains information that specifies the start point node and the end point node. Therefore, the network management system 2 determines a route for setting a wavelength path between the start point node and the end point node. Then, the network management system 2 gives an instruction to set the wavelength path corresponding to the demand to the start point node, the end point node, and each node on the route. The network management system 2 is an example of a management device that manages wavelength paths in the optical network 1.

The network management system 2 estimates the transmission quality of the wavelength path to be set. Therefore, the network management system 2 includes a transmission quality estimation device 3 that estimates the transmission quality of the wavelength path. The transmission quality estimation device 3 estimates the transmission quality of the wavelength path to be set, and compares the estimated value with a predetermined threshold value. Then, when the estimated value of the transmission quality of the wavelength path is worse than the threshold value, the network management system 2 resets the wavelength path so that the optical signal is reproduced on the path between the start point node and the end point node. To do. The transmission quality estimation device 3 may be mounted in the network management system 2 or may be provided outside the network management system 2.

The transmission quality estimation device 3 estimates the transmission quality of each transmission section on the path of the wavelength path, and estimates the transmission quality of the wavelength path based on the estimated value of the transmission quality of each transmission section. In this example, the transmission quality estimation device 3 estimates the optical signal-to-noise ratio (OSNR) as the transmission quality. Further, in the following description, a transmission section corresponding to two nodes adjacent to each other may be referred to as a "span". In this case, for example, the transmission section between node # A and node # B is called "span AB", and the transmission section between node # B and node # C is called "span BC".

In this way, the transmission quality estimation device 3 estimates the OSNR of each span on the path of the wavelength path, and estimates the OSNR of the wavelength path based on the estimated value of the OSNR of each span. Therefore, first, the OSNR of the span will be briefly described.

As shown in FIG. 2, the span is composed of nodes adjacent to each other and optical fibers between them. Therefore, as shown in FIG. 3A, the optical signal propagating in each span is attenuated by passing through the optical fiber and amplified by the optical amplifier in the ROADM. L represents the amount of attenuation due to the optical fiber, and G represents the gain of the optical amplifier. Here, it is assumed that the signal power and the noise power of the input light of the span are Sin and Nin, respectively. In this case, the output light of the span is represented by Eq. (1).

ＳoutおよびＮoutは、それぞれ、出力光の信号パワーおよび雑音パワーを表す。また、ＯＳＮＲoutは、出力信号のＯＳＮＲを表す。Ｎaは、スパン中で発生する雑音パワーを表す。この雑音パワーＮaは、スパン中の光アンプにおいて発生するＡＳＥ雑音等に起因する。

Sout and Nout represent the signal power and noise power of the output light, respectively. OSNRout represents the OSNR of the output signal. Na represents the noise power generated in the span. This noise power Na is caused by ASE noise and the like generated in the optical amplifier in the span.

Here, in order to maintain the signal power of the optical signal at a constant level in the process of propagating the optical signal over one or more spans, the optical amplifier adjusts the product of L and G to be "1". It is assumed that it has been done. In this case, the output light of the span is represented by Eq. (2).

The OSNR out of the output light of the span depends on the input noise power Nin as shown in the equation (2). However, in order to express the transmission characteristics of the span, it is preferable that there is no influence of the input noise power Nin. Therefore, in the following description, the value obtained by giving zero to the input noise power Nin in the equation (2) is defined as the OSNR of the span. That is, the OSNR of the span is expressed by the equation (3).

Next, the OSNR of the path composed of two consecutive spans (# 1, # 2) shown in FIG. 3 (b) will be examined. Note that L1, G1, and Na1 represent noise power caused by the amount of attenuation by the optical fiber in span # 1, the gain of the optical amplifier, ASE noise generated in the span, and the like. L2, G2, and Na2 represent the noise power caused by the attenuation of the optical fiber in span # 2, the gain of the optical amplifier, the ASE noise generated in the span, and the like. In this case, the output light of span # 2 is represented by Eq. (4).

Here, it is assumed that each optical amplifier is adjusted so that the product of L1 and G1 is "1" and the product of L2 and G2 is "1". In this case, the output light of span # 2 is represented by Eq. (5).

Further, when zero is given to the input noise power Nin in the equation (5), the OSNR of the path composed of spans # 1 and # 2 can be obtained. That is, the OSNR of the path is expressed by Eq. (6).

As described above, the OSNR of the path composed of a plurality of consecutive spans is calculated based on the sum of the reciprocals of the OSNRs of each span. Therefore, when estimating the OSNR of the requested wavelength path, the transmission quality estimation device 3 acquires the OSNR of each span on the path of the wavelength path.

The OSNR of each span depends on the noise power generated in the span as shown in the equation (3). This noise power is determined based on the span distance (optical fiber length), the type of optical fiber, the characteristics of the optical amplifier mounted in the span, and the like. Therefore, this noise power is known. That is, the OSNR of each span can be calculated in advance by measurement, simulation, or the like.

However, in a WDM optical network, the OSNR of wavelength paths depends on the number of wavelength paths multiplexed in the optical fiber. Specifically, when the number of wavelength paths multiplexed in the optical fiber increases, the transmission quality of each wavelength path deteriorates due to the non-linear effect, crosstalk, and the like. Therefore, it is preferable that the OSNR of each span is calculated by measurement, simulation, or the like, and then corrected in consideration of the wavelength division multiplexing number.

However, as described above, it is difficult to predict the future wavelength division multiplexing of each span of the WDM optical network. Therefore, the transmission quality estimation device 3 predicts the wavelength division multiplexing number of each span based on the topology of the WDM optical network.

FIG. 4 is a diagram illustrating the relationship between the topology of the optical network and the wavelength division multiplexing number. In this example, one wavelength path is set between each node. Specifically, between nodes # A- # B, between nodes # A- # C, between nodes # A- # D, between nodes # A- # E, between nodes # A- # F, and between nodes # B- #. Between C, between nodes # B- # D, between nodes # B- # E, between nodes # B- # F, between nodes # C- # D, between nodes # C- # E, between nodes # C- # F , Nodes # D- # E, nodes # D- # F, and nodes # E- # F, respectively, one wavelength path is set.

In this case, five wavelength paths are multiplexed in each of the span AB and the span EF. Further, in the span BC and the span DE, eight wavelength paths are multiplexed. Further, in the span CD, nine wavelength paths are multiplexed. That is, the number of wavelength division multiplexing is large in the span arranged near the center of the optical network. On the other hand, in a span located far from the center of the optical network, the wavelength division multiplexing is reduced.

Therefore, the transmission quality estimation device 3 uses this characteristic to predict the wavelength division multiplexing of each span. Specifically, the transmission quality estimation device 3 predicts the wavelength division multiplexing of each span by utilizing the mediation centrality of the topology.

Mediation centrality is one of the indicators of the importance of points on a graph and is calculated based solely on the topology of the graph. Specifically, the mediation centrality C is calculated by Eq. (7).

As an example, in the graph shown in FIG. 5, the mediation centrality of node # 4 is calculated. Note that this graph has nodes # 1 to # 4. Further, nodes # 1- # 4, nodes # 2- # 4, and nodes # 3- # 4 are connected to each other.

The number of shortest paths between node # j and node # k is 6 (R12, R13, R14, R23, R24, R34). The number of shortest paths passing through node # 4 is three (R12, R13, R23). Therefore, the mediation centrality of node # 4 is "3/6".

In the transmission quality estimation method of the embodiment of the present invention, the definition of mediation centrality is extended so that the centrality of each span is represented by mediation centrality. That is, extended mediation centrality is used as an indicator of how close each span is to the center of the optical network. Specifically, the centrality C (s) of each span is expressed by Eq. (8). Note that s identifies a span in the optical network.

In the graph shown in FIG. 5, for example, the centrality C (1-4) of the span between node # 1 and node # 4 is calculated as follows. That is, the number of shortest paths between node # j and node # k is 6 (R12, R13, R14, R23, R24, R34). The number of shortest paths passing through the span between node # 1 and node # 4 is three (R12, R13, R14). Therefore, the centrality C (1-4) of this span is "3/6".

When setting a wavelength path on an optical network according to demand, it is preferable to provide a redundant path in order to improve service continuity. In this case, wavelength paths are set between the start point node and the end point node on a plurality of physically different paths. In the n-redundant configuration, the centrality C (s) of each span is represented by Eq. (9). The n-redundant configuration means a network in which n wavelength paths are set between the start point node and the end point node.

<First Embodiment>
FIG. 6 shows an example of the transmission quality estimation device 10 according to the first embodiment. As shown in FIG. 6, the transmission quality estimation device 10 includes a centrality calculation unit 11, a wavelength division multiplexing number prediction unit 12, a span transmission quality calculation unit 13, a transmission quality database 14, a path calculation unit 15, and a path transmission quality calculation unit 16. , The determination unit 17 is provided. The transmission quality estimation device 10 may have other functions or elements not shown in FIG.

The centrality calculation unit 11 calculates the centrality of each span based on the network configuration information. The network configuration information includes topology information representing the topology of the optical network. Topology information represents the nodes that make up an optical network and the optical fiber links that connect between the nodes. Then, the network configuration information is given to the transmission quality estimation device 10 by, for example, the network administrator. The centrality of the span represents how close the span is to the center of the optical network, and is calculated by, for example, Eq. (8). Thus, the centrality of each span is determined based on the topology of the optical network, regardless of demand (here, the requirement to set the wavelength path).

In a configuration in which the optical network provides redundant paths, the centrality calculation unit 11 calculates the centrality of each span in consideration of the redundancy of the paths. Redundancy information representing the redundancy of the path is given to the transmission quality estimation device 10 by the user or the network administrator. In this case, the centrality of the span is calculated by, for example, Eq. (9).

The wavelength division multiplexing number prediction unit 12 predicts the wavelength division multiplexing number of each span based on the centrality calculated by the centrality calculation unit 11. The wavelength division multiplexing number represents the number of wavelengths (specifically, wavelength paths) to be multiplexed in the optical fiber.

The span transmission quality calculation unit 13 calculates the transmission quality of each span based on the network configuration information, the penalty information, and the wavelength division multiplexing number predicted by the wavelength division multiplexing number prediction unit 12. In this embodiment, the optical signal-to-noise ratio (OSNR) is calculated as the transmission quality. Further, the penalty information represents the amount of deterioration of OSNR due to the non-linear effect generated between the optical signals, crosstalk, and the like when a plurality of wavelength paths are multiplexed in the optical fiber. Here, the amount of deterioration of OSNR due to the non-linear effect and crosstalk depends on the number of wavelength paths multiplexed in the optical fiber. That is, the penalty depends on the wavelength division multiplexing. In this embodiment, it is assumed that the penalty information is generated in advance for the wavelength division multiplexing number by measurement, simulation, or the like. The penalty depends on the wavelength division multiplexing number, the wavelength arrangement, and the like, but in this embodiment, it is assumed that the penalty is uniquely calculated for the wavelength division multiplexing number for the sake of simplicity.

The span transmission quality calculation unit 13 first calculates the basic OSNR for each span. The basic OSNR is calculated by, for example, Eq. (3). That is, the basic OSNR is calculated based on the ASE noise power generated in the optical amplifier in the span. The ASE noise power depends on the characteristics of the optical amplifier and is known. In the case where the basic OSNR of each span is calculated in advance and stored in the memory, the span transmission quality calculation unit 13 acquires the basic OSNR of each span from the memory.

Subsequently, the span transmission quality calculation unit 13 corrects the basic OSNR for each span according to the wavelength division multiplexing number predicted by the wavelength division multiplexing number prediction unit 12. Specifically, a penalty corresponding to the wavelength division multiplexing number predicted by the wavelength division multiplexing number prediction unit 12 is added to the basic OSNR of each span. As a result, an estimate of the OSNR for each span is generated. Then, the calculation result by the span transmission quality calculation unit 13 is stored in the transmission quality database 14 as the transmission quality information.

FIG. 7 shows an example of the transmission quality database 14. The span number identifies each span in the optical network. As described above, the basic OSNR is calculated based on the ASE noise power generated in the optical amplifier in the span. As described above, the wavelength division multiplexing number is predicted by the wavelength division multiplexing number prediction unit 12. The penalty is derived according to the wavelength division multiplexing. The OSNR estimate is obtained by correcting the basic OSNR with a penalty corresponding to the wavelength division multiplexing. For example, the OSNR estimate is calculated by adding a penalty corresponding to the basic OSNR. However, the basic OSNR, the wavelength division multiplexing number, and the penalty do not have to be stored in the transmission quality database 14. In this way, the transmission quality database 14 stores OSNR estimates corresponding to the number of wavelength paths to be multiplexed for each span in the optical network.

The path calculation unit 15 specifies a wavelength path that satisfies a given demand. The demand contains information that represents a start point node and an end point node (or nodes at both ends of the path). Therefore, the path calculation unit 15 determines the path and wavelength channel between the start point node and the end point node specified by the demand. As the route, for example, the shortest route among the routes connecting the start point node and the end point node is selected. As the wavelength channel, for example, the channel having the shortest wavelength among the unused wavelength channels on the selected path is selected. In the following description, the wavelength path specified by the path calculation unit 15 may be referred to as a “target wavelength path”. In a configuration in which the optical network provides redundant paths, the path calculation unit 15 specifies a plurality of wavelength paths between the start point node and the end point node.

The path transmission quality calculation unit 16 identifies one or a plurality of spans constituting the path in which the target wavelength path is set. In the following description, the span constituting the path in which the target wavelength path is set may be referred to as “target span”. Then, the path transmission quality calculation unit 16 acquires the OSNR estimated value of each target span by referring to the transmission quality database 14. Further, the path transmission quality calculation unit 16 estimates the OSNR of the target wavelength path from the OSNR estimated value of each target span.

The determination unit 17 compares the OSNR estimated value of the target wavelength path calculated by the path transmission quality calculation unit 16 with a predetermined threshold value. This threshold is determined, for example, to satisfy the error rate required by the optical network. In this case, the threshold value is predetermined by the designer or administrator of the optical network by measurement, simulation, or the like. Then, the determination unit 17 determines whether or not the OSNR estimated value of the target wavelength path is higher than the threshold value.

FIG. 8 is a flowchart showing an example of preprocessing of the transmission quality estimation method according to the first embodiment. The pre-processing is performed by the transmission quality estimation device 10 before the network management system accepts the demand. Further, the pre-processing includes a process of creating a transmission quality database 14.

In S1, the centrality calculation unit 11 calculates the centrality of each span based on the network configuration information. The centrality of a span represents how close the span is to the center of the optical network, as described above. The centrality of the span is calculated by, for example, Eq. (8) or Eq. (9).

In S2, the wavelength division multiplexing number prediction unit 12 predicts the wavelength division multiplexing number of each span based on the centrality calculated by the centrality calculation unit 11. The wavelength division multiplexing number represents the number of wavelengths (specifically, wavelength paths) to be multiplexed in the optical fiber. As an example, the wavelength division multiplexing number prediction unit 12 predicts the wavelength division multiplexing number M (s) of the span s by using the equation (10).

In equation (10), C (s) represents the centrality calculated by the centrality calculation unit 11 for the span s. max {C (s)} represents the maximum calculated centrality for all spans in the optical network. The maximum number of wavelengths that can be multiplexed represents the number of wavelength channels that can be multiplexed in an optical fiber in a WDM system. Although not particularly limited, the maximum number of wavelengths that can be multiplexed is, for example, 88.

S3 to S6 are executed for each span. In the following description, the span in which the processes S3 to S6 are executed may be referred to as a "target span".

In S3, the span transmission quality calculation unit 13 calculates or acquires the basic OSNR of the target span. As described above, the basic OSNR is calculated based on the ASE noise power generated in the optical amplifier in the span.

In S4, the span transmission quality calculation unit 13 determines the penalty of the target span. The span penalty represents the amount of OSNR degradation due to non-linear effects and crosstalk that occur between optical signals when multiple wavelength paths are multiplexed in an optical fiber. Here, the amount of deterioration of OSNR due to the non-linear effect and crosstalk depends on the number of wavelength paths multiplexed in the optical fiber. That is, the penalty depends on the wavelength division multiplexing. Therefore, the span transmission quality calculation unit 13 calculates the penalty according to the wavelength division multiplexing number predicted by the wavelength division multiplexing number prediction unit 12. When the penalty is calculated in advance for the wavelength division multiplexing number and stored in the memory, the span transmission quality calculation unit 13 determines the penalty value corresponding to the wavelength division multiplexing number predicted by the wavelength division multiplexing number prediction unit 12. It may be obtained from memory.

In S5, the span transmission quality calculation unit 13 estimates the OSNR of the target span from the basic OSNR and the penalty of the target span. Specifically, the OSNR estimated value of the target span can be obtained by adding a penalty corresponding to the basic OSNR of the target span.

In S6, the span transmission quality calculation unit 13 adds the OSNR estimated value of the target span to the transmission quality database 14. Therefore, the transmission quality database 14 is created by executing the processes S3 to S6 for all the spans in the optical network.

FIG. 9 is a flowchart showing an example of processing for estimating the transmission quality of the wavelength path in the first embodiment. The processing of this flowchart is executed, for example, when a demand is given to the network management system.

In S11, the transmission quality estimation device 10 acquires the demand given to the network management system. In S12, the path calculation unit 15 specifies a wavelength path that satisfies the demand. The demand contains information that represents a start point node and an end point node (or nodes at both ends of the path). Therefore, the path calculation unit 15 determines the path and wavelength channel between the start point node and the end point node specified by the demand. In the following description, the wavelength path specified by the path calculation unit 15 may be referred to as a “target wavelength path”.

In S13, the path transmission quality calculation unit 16 specifies one or a plurality of spans constituting the path in which the target wavelength path is set. That is, the span that constitutes the route between the start point node and the end point node is specified. In the following description, the span constituting the path in which the target wavelength path is set may be referred to as “target span”. In S14, the path transmission quality calculation unit 16 acquires the OSNR estimated value of each target span by referring to the transmission quality database 14.

In S15, the path transmission quality calculation unit 16 calculates the OSNR of the target wavelength path from the OSNR estimated value of each target span. The OSNR of the target wavelength path is calculated by Eq. (11).

（１１）式で使用される変数ｓ_dは、目的波長パスが設定される経路上の各スパン（すなわち、各目的スパン）を識別する。ＯＳＮＲ(s_d)は、ｓ_dにより識別される目的スパンのＯＳＮＲ推定値を表す。このように、目的波長パスのＯＳＮＲは、各目的スパンのＯＳＮＲ推定値の逆数の和の逆数を計算することで得られる。

_{The variable s d} used in equation (11) identifies each span (ie, each target span) on the path on which the target wavelength path is set. OSNR (s _d ) represents the OSNR estimate of the target span identified by _{s d.} In this way, the OSNR of the target wavelength path can be obtained by calculating the reciprocal of the sum of the reciprocals of the OSNR estimates of each target span.

In S16, the determination unit 17 compares the OSNR estimated value of the target wavelength path with a predetermined threshold value. This threshold is determined, for example, to satisfy the error rate required by the optical network. Then, if the OSNR estimated value of the target wavelength path is equal to or greater than the threshold value, the process of the transmission quality estimation device 10 ends. On the other hand, if the OSNR estimated value of the target wavelength path is lower than the threshold value, the determination unit 17 divides the target wavelength path into a plurality of wavelength paths in S17. At this time, the target wavelength path is divided into, for example, two wavelength paths. In this case, it is preferable that the transmission distances of the two wavelength paths do not differ significantly from each other. In addition, each wavelength path is set so that the optical signal is reproduced at the node where the target wavelength path is divided.

For example, in the optical network shown in FIG. 1, a demand representing a wavelength path connecting ROADM # 1 and # 5 is given, and the OSNR estimated value of this wavelength path is lower than the threshold value. In this case, the determination unit 17 divides the wavelength path connecting ROADM # 1 and # 5 into the wavelength path connecting ROADM # 1 and # 3 and the wavelength path connecting ROADM # 3 and # 5. .. Further, the optical signal transmitted via each wavelength path is reproduced in ROADM # 3.

After that, the process of the transmission quality estimation device 10 returns to S12. That is, the processes of S12 to S16 are repeatedly executed until the estimated OSNR value of each wavelength path becomes equal to or higher than the threshold value.

Next, an example of creating the transmission quality database 14 and estimating the transmission quality of the requested wavelength path will be described. As shown in FIG. 10, the optical network of this embodiment includes nodes # A to # F. s1 to s8 represent spans. For example, s1 represents the span between nodes # A and # B, and s2 represents the span between nodes # B and # C. The three values assigned to each span represent centrality C (s), wavelength division multiplexing M (s), and OSNR estimates.

The centrality of each span is calculated using Eq. (8) or Eq. (9) in S1 shown in FIG. In the example shown in FIG. 10, the centrality is calculated by the equation (8).

The wavelength division multiplexing number of each span is calculated by the equation (10) in S2 shown in FIG. In the example shown in FIG. 10, the maximum value max {C (s)} in the centrality C (s) of each span is “4/15”. The maximum number of wavelengths that can be multiplexed is 88. Then, the predicted value of the wavelength division multiplexing number calculated for each span is as shown in FIG. For example, the wavelength division multiplexing number prediction value M (s1) of the span s1 is calculated as follows.
M (s1) = {(2/15) / (4/15)} x 88 = 44
Further, for example, the wavelength division multiplexing number prediction value M (s2) of the span s2 is calculated as follows.
M (s2) = {(4/15) / (4/15)} x 88 = 88

The OSNR estimate for each span is calculated according to S3 to S5 shown in FIG. That is, the basic OSNR is calculated based on the ASE noise power generated in the optical amplifier in the span. In addition, the penalty is determined based on the wavelength division multiplexing number. For example, for span s1, a penalty corresponding to the state where the wavelength division multiplexing number is 44 is obtained, and for span s2, a penalty corresponding to the state where the wavelength division multiplexing number is 88 is obtained. In addition, the OSNR estimate is calculated from the base OSNR and the corresponding penalty. Then, the OSNR estimated value calculated for each span is stored in the transmission quality database 14. In this example, the OSNR estimated value of each span is represented by "OSNR (s)". For example, OSNR (1) represents the OSNR estimate for span s1 and OSNR (2) represents the OSNR estimate for span s2.

Here, it is assumed that the transmission quality estimation device 10 is given a demand requesting a wavelength path connecting the nodes # A and the nodes # C. Then, in response to this demand, the path calculation unit 15 shall specify a wavelength path from node # A to node # C via node # B.

In this case, span s1 and span s2 are specified as spans constituting the path in which this wavelength path is set. Then, the path transmission quality calculation unit 16 acquires the OSNR estimated values (OSNR (1), OSNR (2)) of the span s1 and the span s2 from the transmission quality database 14. Then, the path transmission quality calculation unit 16 calculates the OSNR of the wavelength path from the acquired OSNR estimated value. In this case, the OSNR estimate of this wavelength path is calculated by Eq. (12).

If the OSNR estimation value of the wavelength path is smaller than the threshold value, the transmission quality estimation device 10 divides the wavelength path so that the optical signal is reproduced at the node # B, and estimates the transmission quality of each wavelength path obtained by the division. To do. On the other hand, if the OSNR estimate of the wavelength path is greater than or equal to the threshold, the network management system gives instructions to nodes # A, # B, and # C to set the wavelength path. As a result, the wavelength path corresponding to the demand is actually set.

As described above, the transmission quality estimation device 10 according to the first embodiment predicts the wavelength division multiplexing number of each span based on the topology of the optical network, and estimates the OSNR of the wavelength path using the prediction result. Therefore, as compared with the method of estimating the OSNR on the premise that all the wavelength channels are used in all the spans, the method according to the first embodiment removes an excessive margin regarding the wavelength division multiplexing number. Therefore, the accuracy of the OSNR estimation is improved, and the OSNR estimation value is not significantly smaller than the actual OSNR. As a result, an excessive number of repetitive repeaters are not mounted on the optical network, and the cost of the optical network can be reduced.

It is not necessary to prepare the span penalty for all the wavelength division multiplexings, but it may be prepared only for some representative values k. For example, when the maximum number of wavelengths that can be multiplexed is 88, 22, 44, 66, 88 are set as representative values k. That is, the corresponding penalties (P22, P44, P66, P88) are prepared for the _{states where the wavelength division multiplexing number is 22} , ₄₄ , ₆₆ , _{88, respectively.}

In this case, the span transmission quality calculation unit 13 calculates the wavelength division multiplexing number M (s) in S4 of FIG. 8, and then selects the smallest representative value among the representative values larger than M (s). For example, when the predicted value M (s) of the wavelength division multiplexing number of a certain span is 35, 44 is selected as the representative value of the span. Then, the span transmission quality calculation unit 13 _{acquires the penalty P 44 in} S4, and estimates the OSNR of the span from the basic OSNR of the span and the penalty P _{44 in S5.} According to this configuration, the penalty value to be prepared in advance is reduced, so that the measurement or simulation for that purpose becomes easy.

<Second embodiment>
In the first embodiment, the wavelength division multiplexing of each span is predicted based on the topology of the optical network. On the other hand, in the second embodiment, after the initial predicted value of the wavelength division multiplexing number of each span is calculated based on the topology of the optical network, the predicted value is updated according to the actual demand.

FIG. 11 shows an example of the transmission quality estimation device 20 according to the second embodiment. As shown in FIG. 11, the transmission quality estimation device 20 includes a centrality calculation unit 11, a path calculation unit 15, a determination unit 17, a span transmission quality calculation unit 21, a transmission quality database 22, an auxiliary database 23, and a centrality correction unit 24. , Convergence determination unit 25, wavelength division multiplexing number prediction unit 26, and path transmission quality calculation unit 27. The transmission quality estimation device 20 may have other functions or elements not shown in FIG.

The span transmission quality calculation unit 21 calculates the OSNR corresponding to the wavelength division multiplexing for each span based on the network configuration information and the penalty information. The network configuration information includes topology information representing the topology of the optical network, as in the first embodiment. The penalty information represents the amount of deterioration of OSNR due to the non-linear effect generated between the optical signals and the crosstalk with respect to the wavelength division multiplexing, as in the first embodiment. Then, the calculation result by the span transmission quality calculation unit 21 is stored in the transmission quality database 22 as the transmission quality information.

FIG. 12 shows an example of the transmission quality database 22. The transmission quality database 22 stores OSNR estimates for each span and for wavelength division multiplexing. The OSNR estimated value is represented by "OSNR (s, k)". s identifies the span within the optical network. k represents a wavelength division multiplexing number. For example, OSNR (1,2) represents an OSNR estimate when two wavelength paths are multiplexed in span s1, and OSNR (1,88) is an OSNR estimate in which 88 wavelength paths are multiplexed in span s1. Represents the OSNR estimate when it is multiplexed.

The centrality calculation unit 11 calculates the centrality of each span based on the network configuration information, as in the first embodiment. Further, in the configuration in which the optical network provides redundant paths, the centrality calculation unit 11 calculates the centrality of each span in consideration of the redundancy of the paths. Then, the centrality information representing the centrality calculated for each span is stored in the auxiliary database 23.

FIG. 13 shows an example of the auxiliary database 23. The centrality C (s) calculated by the centrality calculation unit 11 is stored in the auxiliary database 23 for each span. When the centrality C (s) is corrected by the centrality correction unit 24, the corrected value is stored in the auxiliary database 23. That is, the value of the centrality C (s) stored in the auxiliary database 23 can be updated by the centrality correction unit 24. The auxiliary database 23 also stores the predicted value M (s) of wavelength multiplexing for each span. The predicted value M (s) of wavelength multiplexing will be described later.

The path calculation unit 15 specifies a wavelength path that satisfies the given demand, as in the first embodiment. In the following description, the wavelength path specified by the path calculation unit 15 may be referred to as a “target wavelength path”. In a configuration in which the optical network provides redundant paths, the path calculation unit 15 sets a plurality of wavelength paths between the start point node and the end point node.

The centrality correction unit 24 corrects the centrality of each span calculated by the centrality calculation unit 11 according to the demand. That is, the centrality of each span calculated based on the topology of the optical network is updated based on the wavelength path actually set according to the demand. The calculation result by the centrality correction unit 24 is stored in the auxiliary database 23.

The convergence determination unit 25 determines whether the centrality corrected by the centrality correction unit 24 has converged for each span. Then, this determination result is given to the wavelength division multiplexing number prediction unit 26.

The wavelength division multiplexing number prediction unit 26 predicts the wavelength division multiplexing number for each span based on the centrality stored in the auxiliary database 23. Therefore, when the centrality is corrected by the centrality correction unit 24, the wavelength division multiplexing number prediction unit 26 predicts the wavelength division multiplexing number based on the corrected centrality. However, at the time of initial operation of the transmission quality estimation device 20, the wavelength division multiplexing number is set to a predetermined initial value. Further, the wavelength division multiplexing number is set to the initial value even when the convergence determination unit 25 determines that the corrected centrality has not converged. The initial value of the wavelength division multiplexing number is the maximum value of the number of wavelength channels that can be set in the WDM system (that is, the maximum number of wavelengths that can be multiplexed).

The path transmission quality calculation unit 27 identifies one or a plurality of spans constituting the path in which the target wavelength path is set. Then, the path transmission quality calculation unit 27 acquires the OSNR estimated value corresponding to the wavelength division multiplexing number from the transmission quality database 22 for each specified span. Then, the path transmission quality calculation unit 27 estimates the OSNR of the target wavelength path from one or a plurality of OSNR estimated values acquired from the transmission quality database 22.

Similar to the first embodiment, the determination unit 17 compares the OSNR estimated value of the target wavelength path calculated by the path transmission quality calculation unit 27 with a predetermined threshold value. Then, the determination unit 17 determines whether or not the OSNR estimated value of the target wavelength path is higher than the threshold value.

FIG. 14 is a flowchart showing an example of preprocessing of the transmission quality estimation method in the second embodiment. The pre-processing is performed by the transmission quality estimation device 20 before the network management system accepts the demand. Further, the pre-processing includes a process of creating a transmission quality database 22.

S21 to S23 are executed for all spans in the optical network. In the following description, the span in which the processes of S21 to S23 are executed may be referred to as "target span".

In S21, the span transmission quality calculation unit 21 calculates or acquires the basic OSNR of the target span. As described above, the basic OSNR is calculated based on the ASE noise power generated in the optical amplifier in the span.

S22 to S23 are executed for each wavelength division multiplexing number. For example, when the maximum number of wavelengths that can be multiplexed is 88, S22 to S23 are executed for each span and for each of the wavelength division multiplexing numbers 1 to 88, respectively.

In S22, the span transmission quality calculation unit 21 estimates the OSNR of the target span from the basic OSNR of the target span and the corresponding penalty. Specifically, the OSNR estimated value is calculated by adding a penalty corresponding to the wavelength division multiplexing number to the basic OSNR of the target span. In S23, the span transmission quality calculation unit 21 adds the OSNR estimated value of the target span to the transmission quality database 22. Therefore, the transmission quality database 22 shown in FIG. 12 is created by executing the processes S21 to S23 for all the spans in the optical network.

In S24, the centrality calculation unit 11 calculates the centrality of each span based on the network configuration information. The centrality of the span is calculated by Eq. (8) or (9) as described above. In S25, the wavelength division multiplexing number prediction unit 26 sets an initial prediction value of the wavelength division multiplexing number. The initial predicted value of the wavelength division multiplexing number is "the maximum number of wavelengths that can be multiplexed (for example, 88)" in this embodiment.

15 to 16 are flowcharts showing an example of the process of estimating the transmission quality of the wavelength path in the second embodiment. The processing of this flowchart is executed, for example, when a demand is given to the network management system.

S31 to S33 are practically the same as S11 to S13 shown in FIG. That is, in S31, the transmission quality estimation device 20 acquires the demand. In S32, the path calculation unit 15 specifies a wavelength path that satisfies the demand. In the following description, the wavelength path specified by the path calculation unit 15 may be referred to as a “target wavelength path”. In S33, the path transmission quality calculation unit 27 identifies one or a plurality of spans constituting the path in which the target wavelength path is set. In the following description, the span constituting the path in which the target wavelength path is set may be referred to as “target span”.

In S34, the wavelength division multiplexing number prediction unit 26 acquires the centrality C (s) of each target span by referring to the auxiliary database 23. Subsequently, the wavelength division multiplexing number prediction unit 26 calculates the predicted value M (s) of the wavelength division multiplexing number from the centrality C (s) for each target span by using the equation (10). Alternatively, in the case where the predicted value of the wavelength division multiplexing number of each span is stored in the auxiliary database 23, the wavelength division multiplexing number prediction unit 26 obtains the predicted value M (s) of the wavelength division multiplexing number of each target span from the auxiliary database 23. You may get it. Then, the wavelength division multiplexing number prediction unit 26 gives the predicted value M (s) of the wavelength division multiplexing number calculated or acquired for each target span to the path transmission quality calculation unit 27.

In S35, the path transmission quality calculation unit 27 acquires the OSNR estimated value of each target span by referring to the transmission quality database 22 shown in FIG. At this time, the transmission quality database 22 is referred to using the predicted value M (s) of the wavelength division multiplexing number of each target span. For example, when the predicted value M (s) of the wavelength division multiplexing number of the span s1 is 88, the path transmission quality calculation unit 27 acquires "OSNR (1,88)" from the transmission quality database 22.

In S36, the path transmission quality calculation unit 16 calculates the OSNR of the target wavelength path from the OSNR estimated value of each target span. The OSNR of the target wavelength path is calculated by Eq. (13).

（１３）式で使用される変数ｓ_dは、各目的スパンを識別する。ｋは、ｓ_dにより識別される目的スパンの波長多重数の予測値を表す。ＯＳＮＲ(s_d,k)は、ｓ_dにより識別される目的スパンにおいて波長多重数がｋであるときのＯＳＮＲ推定値を表す。

_{The variable s d} used in equation (13) identifies each target span. k represents a predicted value of the wavelength division multiplexing of the target span identified by _{s d.} OSNR (s _d , k) represents an OSNR estimate when the wavelength division multiplexing is k in the target span identified by _{s d.}

S37 to S38 are substantially the same as S16 to S17 shown in FIG. That is, in S37, the determination unit 17 compares the OSNR estimated value of the target wavelength path with a predetermined threshold value. Then, if the OSNR estimated value of the target wavelength path is lower than the threshold value, the determination unit 17 divides the target wavelength path into a plurality of wavelength paths in S38. However, if the OSNR estimated value of the target wavelength path is equal to or greater than the threshold value, the process of the transmission quality estimation device 20 proceeds to S41.

In S41, the centrality correction unit 24 increments the demand counter. The demand counter counts the number of demands given to the transmission quality estimation device 20 (or the number of added demands).

In S42, the centrality correction unit 24 determines whether the count value of the demand counter is a multiple of a predetermined number L. L is a positive integer and represents the interval at which the centrality of the span is updated. If the count value of the demand counter is a multiple of L, the process of the transmission quality estimation device 20 proceeds to S43. On the other hand, if the count value is not a multiple of L, the process of the transmission quality estimation device 20 ends.

In S43, the centrality correction unit 24 corrects the centrality C (s) of each span according to the wavelength path added after the previous update process. At this time, the centrality C (s) is updated using the equation (14).

（１４）式において、Ｃ(s)_newは、更新後の中心性を表す。Ｃ(s)_oldは、更新前の中心性を表す。αは、ゼロよりも大きく１よりも小さい実数であり、更新の速度を指定する。

In equation (14), C (s) _new represents the updated centrality. C (s) _old represents the centrality before the update. α is a real number greater than zero and less than 1 and specifies the rate of update.

The initial value of span centrality is calculated based only on the topology of the optical network. After this, the centrality of the span is corrected according to the wavelength path actually set on the optical network.

In S44 to S45, the convergence determination unit 25 calculates the convergence parameter D for each span. The convergence parameter D represents the degree of convergence of the centrality C (s) corrected in S43. Specifically, the convergence parameter D is calculated by the equation (15). That is, the convergence parameter D represents the absolute value of the difference between the centrality before the update and the centrality after the update.

Then, the convergence determination unit 25 determines whether or not the centrality C (s) corrected by the centrality correction unit 24 has converged by comparing the convergence parameter D with a predetermined threshold value. Specifically, the convergence determination unit 25 determines that the centrality C (s) has converged when the convergence parameter D is smaller than the threshold value. Alternatively, the convergence determination unit 25 may determine that the centrality C (s) has converged when the convergence parameter D is smaller than the threshold value a plurality of times in succession in order to improve reliability.

After the centrality C (s) has converged, the wavelength division multiplexing number prediction unit 26 updates the wavelength division multiplexing number prediction value M (s) in S46 according to the equation (10). When the centrality C (s) is not converged, the wavelength division multiplexing number prediction unit 26 sets the initial value (that is, the maximum number of multiplexable wavelengths) as the predicted value M (s) of the wavelength division multiplexing number in S47. Set. Then, the predicted value M (s) of the wavelength division multiplexing number updated in S46 or S47 is recorded in the auxiliary database 23. The new predicted value M (s) of the wavelength division multiplexing number is used in S34 when the transmission quality estimation device 20 is given the next demand.

Thus, in the second embodiment, after the initial predictions of the centrality of each span and the wavelength division multiplexing are calculated based on the topology of the optical network, the centrality of each span and the centrality of each span are calculated according to the actual demand. The predicted value is updated. Therefore, the accuracy of predicting the wavelength division multiplexing of each span is improved, and the accuracy of estimating the transmission quality of the wavelength path is improved. As a result, an excessive number of repetitive repeaters are not mounted on the optical network, and the cost of the optical network can be reduced.

In addition, since the centrality of each span is corrected when a predetermined number of demands are given to the network management system, the frequency of recalculation of centrality (and multi-length multiplex) is suppressed, and the transmission quality estimation device is used. The load of 20 is reduced. In particular, in a large-scale optical network, even if one wavelength path is added, the change in the centrality of each span is considered to be slight, so the effect of this configuration is great.

Further, since the wavelength division multiplexing number is updated after the corrected centrality has converged, the estimation of the transmission quality of the wavelength path is stable.

As in the first embodiment, in the second embodiment as well, it is not necessary to prepare OSNR predicted values for all wavelength division multiplexings. For example, when 22, 44, 66, 88 are set as representative values of the wavelength division multiplexing number, the transmission quality database 22 corresponds to the OSNR corresponding to the state where the wavelength division multiplexing number is 22, 44, 66, 88, respectively. Store estimates.

In this case, the path transmission quality calculation unit 27 selects the smallest representative value among the representative values larger than M (s) after acquiring the wavelength division multiplexing number M (s) in S34 to S35 of FIG. To do. For example, when the predicted value M (s) of the wavelength division multiplexing number of a certain span is 35, 44 is selected as the representative value of the span. Then, the path transmission quality calculation unit 27 acquires the OSNR (s, 44) from the transmission quality database 22.

<Hardware configuration>
FIG. 17 shows an example of the hardware configuration of the transmission quality estimation device. The transmission quality estimation device is realized by, for example, the computer system 100 shown in FIG. The computer system 100 includes a CPU 101, a memory 102, a storage device 103, a reading device 104, a communication interface 106, and an input / output device 107. The CPU 101, the memory 102, the storage device 103, the reading device 104, the communication interface 106, and the input / output device 107 are connected to, for example, the bus 108.

The CPU 101 uses the memory 102 to execute a transmission quality estimation program that describes the processing of the flowchart shown in FIGS. 8 to 9 or 14 to 16. As a result, the transmission quality estimation method described above is realized. That is, in the first embodiment, the CPU 101 functions as the centrality calculation unit 11, the wavelength division multiplexing number prediction unit 12, the span transmission quality calculation unit 13, the path calculation unit 15, the path transmission quality calculation unit 16, and the determination unit 17. Can be provided. Further, in the first embodiment, the CPU 101 includes a centrality calculation unit 11, a path calculation unit 15, a determination unit 17, a span transmission quality calculation unit 21, a centrality correction unit 24, a convergence determination unit 25, and a wavelength division multiplexing number prediction unit. 26, the function of the path transmission quality calculation unit 27 can be provided.

The memory 102 is, for example, a semiconductor memory, and includes a RAM area and a ROM area. The variables used in the processing of each flowchart are temporarily stored in the memory 102. The storage device 103 is, for example, a hard disk device, and stores the above-mentioned transmission quality estimation program. Further, the storage device 103 can provide the transmission quality databases 14 and 22, and the auxiliary database 23. The storage device 103 may be a semiconductor memory such as a flash memory. Further, the storage device 103 may be an external storage device.

The reading device 104 accesses the removable recording medium 105 according to the instruction of the CPU 101. The removable recording medium 105 includes, for example, a semiconductor device (USB memory, etc.), a medium (magnetic disk, etc.) to which information is input / output by magnetic action, and a medium (CD-ROM, etc.) to which information is input / output by optical action. It is realized by DVD etc.).

The communication interface 106 can transmit and receive data via the network according to the instructions of the CPU 101. That is, the communication interface 106 can access a server existing on the network. The input / output device 107 corresponds to a keyboard, mouse, touch panel, etc. operated by the user. Further, the input / output device 107 outputs the processing result by the CPU 101.

The transmission quality estimation program according to the embodiment is given to the computer system 100 in the following embodiment, for example.
(1) It is pre-installed in the storage device 103.
(2) Provided by the removable recording medium 105.
(3) Provided from a server on the network.

1 Optical network 2 Network management system 3 Transmission quality estimation device 10, 20 Transmission quality estimation device 11 Centrality calculation unit 12, 26 Wave frequency multiplex prediction unit 13, 21 Span transmission quality calculation unit 14, 22 Transmission quality database 15 Path calculation unit 16, 27 Path transmission quality calculation unit 17 Judgment unit 23 Auxiliary database 24 Centrality correction unit 25 Convergence judgment unit

Claims (7)

A management device that manages paths in an optical network that transmits wavelength division multiplexing optical signals.
A storage unit that stores transmission quality values corresponding to the number of wavelengths to be multiplexed for a transmission section on the path set in the optical network.
A centrality calculation unit that calculates the centrality indicating how close the transmission section is to the center of the optical network based on the topology of the optical network.
A prediction unit that predicts the number of wavelengths to be multiplexed in the transmission section based on the centrality calculated by the centrality calculation unit.
For the transmission section, an estimation unit that acquires a transmission quality value corresponding to the number of wavelengths predicted by the prediction unit from the storage unit and estimates the transmission quality of the path based on the acquired transmission quality value.
A management device equipped with. Further provided with a correction unit that corrects the calculated centrality of the transmission section when a path is set in the optical network according to demand.
The prediction unit updates the prediction value of the number of wavelengths to be multiplexed in the transmission section based on the centrality corrected by the correction unit.
When the management device is given a demand to set a new path in the optical network, the estimation unit stores the transmission quality value corresponding to the prediction value of the number of wavelengths updated by the prediction unit. The management device according to claim 1, wherein the transmission quality of the path is estimated based on the transmission quality value obtained from the above. 2. The correction unit is characterized in that it corrects the calculated centrality of the transmission section when a predetermined number of demands for setting a new path in the optical network are given to the management device. The management device described in. A convergence test unit for determining whether the centrality corrected by the correction unit has converged is further provided.
The third aspect of claim 3, wherein the prediction unit updates the predicted value of the number of wavelengths when the convergence determination unit determines that the centrality corrected by the correction unit has converged. Management device. Further provided with a calculation unit for calculating the transmission quality value for the transmission section on the path set in the optical network.
The calculation unit
Based on the ASE noise power of the transmission section, the basic transmission quality value of the transmission section is calculated.
Get a penalty corresponding to the number of wavelengths multiplexed in the optical fiber
The management device according to claim 1, wherein the transmission quality value of the transmission section is calculated by adding the penalty to the basic transmission quality value of the transmission section. A management device that manages paths in an optical network that transmits wavelength division multiplexing optical signals.
A centrality calculation unit that calculates the centrality of each transmission section in the optical network, which indicates how close it is to the center of the optical network, based on the topology of the optical network.
For each transmission section, a prediction unit that predicts the number of wavelengths to be multiplexed based on the centrality calculated by the centrality calculation unit, and
For each transmission section, a storage unit that stores a transmission quality value corrected based on the number of wavelengths predicted by the prediction unit, and a storage unit.
With respect to the transmission section on the path of the path set in the optical network, an estimation unit that acquires the transmission quality value stored in the storage unit and estimates the transmission quality of the path based on the acquired transmission quality value. ,
A management device equipped with. A management method for managing paths in an optical network that transmits wavelength division multiplexing optical signals.
For the transmission section on the path set in the optical network, the transmission quality value corresponding to the number of wavelengths to be multiplexed is calculated.
Based on the topology of the optical network, the centrality representing how close the transmission section is to the center of the optical network is calculated.
Based on the centrality, the number of wavelengths to be multiplexed in the transmission section is predicted.
For the transmission section, the transmission quality value corresponding to the predicted number of wavelengths is acquired, and the transmission quality value is acquired.
The transmission quality of the path is estimated based on the transmission quality value of the transmission section.
A management method characterized by that.

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