Network management device, communication device and network management system

Abstract

The present invention provides a network management device, a communication device, and a network management method that make it possible to improve a transmission capacity. A network management device (NMS) according to the present invention is provided with an insertion control unit (11) and a branch control unit (12). In an optical communication network (100) having a plurality of communication devices (NE) connected via a transmission path in which WDM signal light obtained by subjecting a plurality of optical signals to wavelength division multiplexing is transmitted, when a first communication device (NE) inserts an optical signal into WDM signal light, the insertion control unit (11) controls the first communication device (NE) so that a plurality of optical signals to be branched by a second communication device (NE) are inserted to be adjacent to a wavelength band sandwiched between guard bands, and when the second communication device (NE) branches an optical signal from the WDM signal light, the branch control unit (12) controls the second communication device (NE) so that the plurality of optical signals inserted to be adjacent to a wavelength band sandwiched between guard bands are branched.

Description

[Technical field]

[0001] The present invention relates to a network management device, a communication device, a network management method, and a network management system. [Background technology]

[0002] Patent Document 1 describes an optical communication system in which a modulated signal modulated by a plurality of different modulation methods is given a predetermined guard band based on the bandwidth and the destination.

[0003] Patent Document 2 describes an optical network system in which, when signal light of a plurality of modulation methods is transmitted simultaneously, a guard band is provided between adjacent signal light only when the signal light of different modulation methods is adjacent.

[0004] Patent Document 3 describes a multicarrier communication system that transmits signals by reducing the number of guard intervals in a multicarrier communication method.

[0005] Patent Document 4 describes a base station device that uses a guard time, the length of which allows for a propagation delay between a base station and a mobile station, between channel slots occupied by the same base station. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 141188 [Patent Document 2] JP 2012-195787 A [Patent Document 3] JP 2004-056552 A [Patent Document 4] JP 2000-253443 A Summary of the Invention [Problem to be solved by the invention]

[0007] In optical communications, the signal bandwidth is reduced and the signal quality deteriorates each time the signal passes through a multiplexer, so guard bands are provided to prevent this deterioration in signal quality. However, providing a guard band requires securing a bandwidth wider than the signal bandwidth, which reduces the transmission capacity of the system.

[0008] In view of the above-mentioned problems, an object of the present disclosure is to provide a network management device, a communication device, and a network management method that can improve transmission capacity. [Means for solving the problem]

[0009] A network management device according to one embodiment is provided in an optical communication network having a plurality of communication devices connected by a transmission line that transmits WDM signal light in which a plurality of optical signals are wavelength division multiplexed, the network management device comprising: an insertion control unit that controls a first communication device so that, when a first communication device adds an optical signal to the WDM signal light, the plurality of optical signals dropped by a second communication device are inserted adjacent to a wavelength band sandwiched between guard bands; and a branching control unit that controls the second communication device so that, when the second communication device drops the optical signal from the WDM signal light, the plurality of optical signals inserted adjacent to the wavelength band sandwiched between the guard bands are branched.

[0010] A communication device in one embodiment is connected to an optical communication network having a plurality of communication devices connected by a transmission line that transmits WDM signal light in which a plurality of optical signals are wavelength division multiplexed, and when inserting the optical signal into the WDM signal light, inserts the plurality of optical signals to be dropped by other communication devices adjacent to a wavelength band sandwiched between guard bands, and when dropping the optical signal from the WDM signal light, drops the plurality of optical signals that have been inserted adjacent to the wavelength band sandwiched between the guard bands.

[0011] A network management method according to one embodiment, in an optical communication network having a plurality of communication devices connected by a transmission line that transmits WDM signal light in which a plurality of optical signals are wavelength division multiplexed, comprises the steps of: controlling a first communication device so that, when a first communication device adds an optical signal to the WDM signal light, the plurality of optical signals to be dropped by a second communication device are inserted adjacent to a wavelength band sandwiched between guard bands; and controlling the second communication device so that, when the second communication device drops the optical signal from the WDM signal light, the plurality of optical signals inserted adjacent to the wavelength band sandwiched between the guard bands are dropped. Effect of the Invention

[0012] According to one embodiment, a network management device, a communication device, and a network management method capable of improving transmission capacity are provided. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 illustrates a network management system according to an embodiment. [Diagram 2] FIG. 10 is a diagram for explaining a WDM signal light according to a comparative example. [Diagram 3] 2 is a diagram for explaining a WDM signal light according to an embodiment. FIG. [Figure 4] FIG. 1 is a block diagram illustrating a network management device according to an embodiment. [Diagram 5] FIG. 2 is a flow chart illustrating a network management method according to an embodiment of the present invention. [Figure 6] 1 is a block diagram illustrating a configuration of a communication device according to a first embodiment. [Figure 7] 1 is a block diagram illustrating a configuration of a communication device according to a first embodiment. [Figure 8] 3 is a diagram illustrating a wavelength demultiplexing function of a wavelength selective switch in a wavelength cross-connect function unit according to the first embodiment. FIG. [Figure 9]2 is a diagram illustrating a wavelength multiplexing function of a wavelength selective switch in a wavelength cross-connect function unit according to the first embodiment. FIG. [Figure 10] 1 is a block diagram illustrating a configuration of a network management device according to a first embodiment. [Figure 11] FIG. 1 is a diagram illustrating a network management method according to a comparative example. [Figure 12] FIG. 2 is a diagram illustrating a network management method according to the first embodiment. [Figure 13] 10 is a diagram for explaining a WDM signal light according to a second embodiment. FIG. [Figure 14] FIG. 11 is a block diagram illustrating a network management device according to a second embodiment. [Figure 15] 11 is a graph illustrating an OSNR value obtained by converting a penalty estimated by an estimation unit into an OSNR and an OSNR monitored by a monitoring unit of the network management device in the second embodiment; [Figure 16] 11 is a graph illustrating OSNR values ​​monitored by a monitor unit of a network management device according to a second embodiment and OSNR values ​​obtained by converting penalties estimated by an estimation unit into OSNR. [Figure 17] 13 is a diagram illustrating a method in which an estimation unit of a network management device according to a second embodiment estimates a penalty. FIG. [Figure 18] FIG. 11 is a flow chart illustrating a method for determining the quality of a transmission path in the network management method according to the second embodiment. [Figure 19] 11 is a flow chart illustrating a method for controlling intervals between optical signals in a network management method according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In addition, in each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0015] (Overview of the embodiment) Prior to describing the embodiments of the present disclosure, an overview of the embodiments of the present disclosure will be described. Fig. 1 is a diagram illustrating a network management system according to an embodiment.

[0016] <Network Management System> As shown in FIG. 1, the network management system 1 includes a network management device NMS and an optical communication network 100. The optical communication network 100 includes a plurality of communication devices NE1 to NE4. Although four communication devices NE1 to NE4 are shown in the figure, the number of the communication devices NE1 to NE4 is not limited. Each of the communication devices NE1 to NE4 is connected to the optical communication network via a transmission line. Thus, the optical communication network 100 is configured by connecting a plurality of communication devices NE1 to NE4 with a transmission line. Each of the communication devices NE may be connected in a point-to-point manner, in a ring manner, or in a mesh manner. The communication devices NE1 to NE4 are collectively referred to as a communication device NE. The transmission line transmits a WDM signal light obtained by wavelength division multiplexing a plurality of optical signals. Each of the communication devices NE is connected to the network management device NMS by a communication line.

[0017] <Communication Device> The communication equipment NE is a node of the optical communication network 100. The communication equipment NE may be connected to a transmitter and a receiver (not shown) via a wired or wireless communication line. The communication equipment NE can function as a multiplexer, a relay device, and a demultiplexer under the control of ROADM (Reconfigurable Optical Add and Drop MultiPlexing). The operation of each communication equipment NE is controlled by a network management device NMS. As a result, the optical communication network 100 transmits optical signals by wavelength division multiplexing (WDM).

[0018] <WDM signal light of comparative example> Here, the WDM signal light transmitted through the optical communication network 100 will be described separately for a comparative example and an embodiment. FIG. 2 is a diagram for explaining the WDM signal light according to the comparative example. FIG. 3 is a diagram for explaining the WDM signal light according to the embodiment. As shown in FIGS. 2 and 3, the WDM signal light is divided into a plurality of wavelength bands. A plurality of slots SL correspond to each wavelength band. Thus, a wavelength band has a plurality of slots SL. Slots SL1 to SL24 are shown in FIGS. 2 and 3. First, the comparative example will be described. As shown in FIG. 2, the WDM signal light of the comparative example includes, for example, optical signals P1 to P4.

[0019] The optical signal P1 corresponds to slots SL2 to SL5. Slots SL1 and SL6 are provided with guard bands G1 and G2. The optical signal P2 corresponds to slots SL8 to SL11. Slots SL7 and SL12 are provided with guard bands G3 and G4. The optical signal P3 corresponds to slots SL14 to SL17. Slots SL13 and SL18 are provided with guard bands G5 and G6. The optical signal P4 corresponds to slots SL20 to SL23. Slots SL19 and SL24 are provided with guard bands G7 and G8.

[0020] Optical signal P1 and optical signal P3 are optical signals dropped by the same communication equipment NE. For example, optical signal P1 and optical signal P3 are optical signals dropped by communication equipment NE4. Optical signal P2 and optical signal P4 are optical signals dropped by the same communication equipment NE. For example, optical signal P2 and optical signal P4 are optical signals dropped by communication equipment NE3.

[0021] <WDM signal light of the embodiment> Next, a WDM signal light according to the embodiment will be described. As shown in Fig. 3, the WDM signal light is divided into a plurality of wavelength bands, and a plurality of slots SL correspond to each wavelength band. The WDM signal light includes optical signals P11 to P14.

[0022] The optical signal P11 corresponds to slots SL2 to SL5. The optical signal P12 corresponds to slots SL6 to SL9. The optical signal P11 and the optical signal P12 are optical signals that are dropped by the same communication device NE. For example, the optical signal P11 and the optical signal P12 are optical signals that are dropped by the communication device NE4. The slots SL1 and SL10 are provided with guard bands G11 and G12. The optical signal P13 corresponds to slots SL12 to SL15. The optical signal P14 corresponds to slots SL16 to SL19. The slots SL11 and SL20 are provided with guard bands G13 and G14. The optical signal P13 and the optical signal P14 are optical signals that are dropped by the same communication device NE. For example, the optical signal P13 and the optical signal P14 are optical signals that are dropped by the communication device NE3. In the embodiment, four slots can be reduced compared to the comparative example.

[0023] <Network management device> Fig. 4 is a block diagram illustrating a network management device NMS according to an embodiment. As shown in Fig. 4, the network management device NMS includes an insertion control unit 11 and a branching control unit 12. The insertion control unit 11 and the branching control unit 12 function as an insertion control means and a branching control means.

[0024] In the optical communication network 100, for example, when the communication device NE1 adds an optical signal P12 to a WDM signal light, the add control unit 11 controls the communication device NE1 so that the multiple optical signals P11 and P12 dropped by the communication device NE4 are added adjacent to the wavelength band sandwiched between the guard bands G11 and G12. Also, when the communication device NE1 adds an optical signal P14 to a WDM signal light, the add control unit 11 controls the communication device NE1 so that the multiple optical signals P13 and P14 dropped by the communication device NE3 are added adjacent to the wavelength band sandwiched between the guard bands G13 and G14.

[0025] The branching control unit 12 controls the communication device NE4 so that, when the communication device NE4 branches the optical signals P11 and P12 from the WDM signal light, the optical signals P11 and P12 inserted adjacent to the wavelength band sandwiched between the guard bands G11 and G12 are branched at the communication device NE4. Also, when the communication device NE3 branches the optical signals P13 and P14 from the WDM signal light, the branching control unit 12 controls the communication device NE3 so that the optical signals P13 and P14 inserted adjacent to the wavelength band sandwiched between the guard bands G13 and G14 are branched at the communication device NE3.

[0026] The communication devices NE1 to NE4 are connected to an optical communication network 100 including a plurality of communication devices NE1 to NE4 connected by transmission lines. When the communication device NE1 adds an optical signal P12 to the WDM signal light, the communication device NE1 adds, for example, a plurality of optical signals P11 and P12 dropped by the communication device NE4 adjacent to a wavelength band sandwiched between guard bands G11 and G12. When the communication device NE1 adds an optical signal P14 to the WDM signal light, the communication device NE1 adds, for example, a plurality of optical signals P13 and P14 dropped by the communication device NE3 adjacent to a wavelength band sandwiched between guard bands G13 and G14.

[0027] When the communication device NE3 drops the optical signals P13 and P14 from the WDM signal light, it drops the multiple optical signals P13 and P14 inserted into the wavelength bands sandwiched between the guard bands G13 and G14.

[0028] When the communication device NE4 drops the optical signals P11 and P12 from the WDM signal light, it drops the multiple optical signals P11 and P12 inserted into the wavelength band sandwiched between the guard bands G11 and G12.

[0029] <Network management method> FIG. 5 is a flow chart illustrating a network management method of the network management device NMS according to the embodiment.

[0030] As shown in step S11 of FIG. 5, in the optical communication network 100, when the communication device NE1 adds an optical signal P12 to a WDM signal light, for example, the communication device NE1 is controlled so that multiple optical signals P11 and P12 branched by the same communication device NE4 are inserted adjacent to the wavelength band sandwiched between guard bands G11 and G12.

[0031] Next, as shown in step S12, in the optical communication network 100, when the communication device NE4 drops the optical signals P11 and P12 from the WDM signal light, the communication device NE4 is controlled so that the multiple optical signals P11 and P12 inserted adjacent to the wavelength bands sandwiched between the guard bands G11 and G12 are dropped at the communication device NE4.

[0032] The network management device NMS of the embodiment inserts multiple optical signals branched by the same communication device NE adjacent to each other into wavelength bands sandwiched between guard bands, thereby reducing the guard bands between adjacent optical signals and improving the maximum transmission capacity of the optical communication network.

[0033] (Embodiment 1) Next, a description will be given of the details of the network management system 1 according to the embodiment 1. First, the communication device NE will be described.

[0034] <Communication device configuration> Fig. 6 is a block diagram illustrating a configuration of a communication device NE according to the first embodiment. As shown in Fig. 6, the communication device NE has a wavelength cross connect functional unit 110, a wavelength cross connect functional unit 120, a wavelength multiplexing / demultiplexing functional unit 130, and a transponder functional unit 140. The wavelength cross connect functional unit 110 and the wavelength cross connect functional unit 120 function as wavelength cross connect means. The wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 function as wavelength multiplexing / demultiplexing means and transponder means. The wavelength cross connect functional unit 110, the wavelength cross connect functional unit 120, the wavelength multiplexing / demultiplexing functional unit 130, and the transponder functional unit 140 are also called a first cross connect unit, a second cross connect unit, a wavelength multiplexing / demultiplexing unit, and a transponder unit.

[0035] An amplifier may be connected to the wavelength cross connect functional unit 110 and the wavelength cross connect functional unit 120. A transmitter and a receiver may be connected to the wavelength multiplexing / demultiplexing functional unit 130 via the transponder functional unit 140. A multiplexing device may be configured by the wavelength cross connect functional unit 120 and the wavelength multiplexing / demultiplexing functional unit 130. A demultiplexing device may be configured by the wavelength cross connect functional unit 110 and the wavelength multiplexing / demultiplexing functional unit 130. A relay device may be configured by the wavelength cross connect functional unit 110 and the wavelength cross connect functional unit 120. Note that the relay device may not have the wavelength cross connect functional unit 110 and the wavelength cross connect functional unit 120 and may be configured by an amplifier.

[0036] The wavelength cross-connect functional unit 110 drops a predetermined optical signal from the received WDM signal light. Specifically, the wavelength cross-connect functional unit 110 selects a wavelength band into which the optical signal is dropped and switches it. The wavelength cross-connect functional unit 120 adds a predetermined optical signal to the WDM signal light. Specifically, the wavelength cross-connect functional unit 120 selects a wavelength band into which the optical signal is added and switches it.

[0037] The wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 transmit the optical signal branched by the wavelength cross-connect functional unit 110 to the receiver. Specifically, the wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 receive the branched optical signal from the wavelength band. In this case, the branching control unit 12 controls the wavelength cross-connect functional unit 110, the wavelength multiplexing / demultiplexing functional unit 130, and the transponder functional unit 140. Meanwhile, the wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 combine the optical signals transmitted from the transmitter and transmit them to the wavelength cross-connect functional unit 120. Specifically, the wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 transmit the optical signal to be added to the wavelength band. In this case, the insertion control unit 11 of the network management device NMS controls the wavelength cross-connect functional unit 120, the wavelength multiplexing / demultiplexing functional unit 130, and the transponder functional unit 140.

[0038] 7 is a block diagram illustrating a configuration of the communication equipment NE according to embodiment 1. As shown in FIG. 7, the communication equipment NE may include a wavelength cross-connect function unit 110, a wavelength cross-connect function unit 120, and an NE control unit 150.

[0039] The wavelength cross-connect function unit 110 includes a WSS control unit 111 and a wavelength selective switch 112. The WSS control unit 111 functions as a control means for controlling the operation of the wavelength selective switch 112. The wavelength selective switch 112 functions as a switch means for selecting a predetermined wavelength.

[0040] The wavelength cross-connect function unit 120 includes a WSS control unit 121 and a wavelength selective switch 122. The WSS control unit 121 functions as a control means for controlling the operation of the wavelength selective switch 122. The wavelength selective switch 122 functions as a switch means for selecting a predetermined wavelength.

[0041] The NE control unit 150 is connected to the wavelength cross-connect functional unit 110, the wavelength cross-connect functional unit 120, the network management device NMS, and the transponder functional unit 140. The NE control unit 150 functions as a control means for controlling the operations of the wavelength cross-connect functional unit 110, the wavelength cross-connect functional unit 120, the transponder functional unit 140, and the wavelength multiplexing / demultiplexing functional unit 130 (not shown).

[0042] Fig. 8 is a diagram illustrating a wavelength demultiplexing function of the wavelength selective switch 112 in the wavelength cross-connect function unit 110 according to the embodiment 1. As shown in Fig. 8, when WDM signal light including optical signals of wavelengths λ1 to λN is input to the wavelength selective switch 112, the wavelength selective switch 112 branches the optical signals into predetermined optical signals of wavelengths λ1 to λN.

[0043] Fig. 9 is a diagram illustrating a wavelength multiplexing function of the wavelength selective switch 122 in the wavelength cross-connect functional unit 120 according to the embodiment 1. As shown in Fig. 9, when optical signals of wavelengths λ1 to λN are input, the wavelength selective switch 122 multiplexes the optical signals and outputs a WDM signal light including optical signals of wavelengths λ1 to λN.

[0044] <Network management device configuration> Next, the network management device NMS will be described. Fig. 10 is a block diagram illustrating the configuration of the network management device NMS according to the first embodiment. As shown in Fig. 10, the network management device NMS may include a control unit 10 in addition to an insertion control unit 11 and a branching control unit 12. The control unit 10 has a function as a control means. The network management device NMS is, for example, a computer, and the control unit 10 is, for example, a processor such as a CPU (Central Processing Unit).

[0045] The control unit 10 has a function as a calculation device that performs control processing, calculation processing, etc. The control unit 10 controls the operations of the addition control unit 11 and the branching control unit 12. The control unit 10 may also control various operations of the communication device NE.

[0046] The network management device NMS may have a storage unit, a communication unit, and an interface unit, not shown, in addition to the control unit 10. The storage unit may have a storage device such as a memory or a hard disk. The storage device is, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory). The storage unit has a function for storing a control program and an arithmetic program executed by the control unit 10. The storage unit also has a function for temporarily storing processing data and the like. The storage unit may include a database. The communication unit performs processing required for communicating with other devices via a wired or wireless network or the like. The communication unit may include a communication port, a router, a firewall, and the like. The interface unit is, for example, a user interface. The interface unit has an input device such as a keyboard, a touch panel, or a mouse, and an output device such as a display or a speaker. The interface unit accepts data input operations by a user (an operator, etc.), and outputs information to the user. The control unit 10, the storage unit, the communication unit, and the interface unit are connected to each other via a data bus or the like.

[0047] The network management device NMS has an insertion control unit 11 and a branch control unit 12 as components. Each component can be realized, for example, by executing a program under the control of the control unit 10. More specifically, each component can be realized by the control unit 10 executing a program stored in a storage unit. Each component may be realized by recording a necessary program in an arbitrary non-volatile recording medium and installing it as necessary. Each component may be realized by any combination of hardware, firmware, and software, without being limited to being realized by software based on a program. Each component may be realized by using an integrated circuit programmable by a user, such as a field-programmable gate array (FPGA) or a microcomputer. In this case, the integrated circuit may be used to realize a program composed of each of the above components.

[0048] <Network Management Method of Comparative Example> Next, a network management method will be described as an operation of the network management device NMS of this embodiment. First, a network management method in a comparative example will be described. After that, the network management method of this embodiment will be described in comparison with the comparative example.

[0049] Fig. 11 is a diagram illustrating a network management method according to a comparative example. As shown in Fig. 2 and Fig. 11, the communication device NE1 receives WDM signal light including optical signals P1 and P2. The optical signal P1 is an optical signal that is dropped (branched) by the communication device NE4, and the optical signal P2 is an optical signal that is dropped (branched) by the communication device NE3. Guard bands G1 and G2 are provided in the slots SL1 and SL6 on both sides of the optical signal P1. Guard bands G3 and G4 are provided in the slots SL7 and SL12 on both sides of the optical signal P2. Some symbols are omitted to avoid complicating the diagram.

[0050] The communication device NE1 adds an optical signal P3 to the received WDM signal light and multiplexes it. The optical signal P3 is an optical signal that is dropped by the communication device NE4. The communication device NE1 provides guard bands G5 and G6 in slots SL3 and SL18 on both sides of the optical signal P3. The communication device NE1 outputs the WDM signal light multiplexed by adding the optical signal P3 to the communication device NE2.

[0051] The communication device NE2 receives WDM signal light including optical signals P1, P2, and P3. The communication device NE2 adds optical signal P4 to the received WDM signal light to multiplex it. The optical signal P4 is an optical signal that is dropped by the communication device NE3. The communication device NE2 provides guard bands G7 and G8 in slots SL19 and SL24 on both sides of the optical signal P4. As a result, the WDM signal light includes optical signals P1 to P4, as shown in FIG. 2. The communication device NE2 outputs the WDM signal light, into which the optical signal P4 has been added and multiplexed, to the communication device NE3.

[0052] The communication device NE3 receives a WDM signal light including optical signals P1 to P4. The communication device NE3 drops an optical signal P2 and an optical signal P4 from the WDM signal light. The communication device NE3 outputs the WDM signal light from which the optical signals P2 and P4 have been dropped to the communication device NE4.

[0053] The communication device NE4 receives the WDM signal light including the optical signals P1 and P3. The communication device NE4 drops the optical signals P1 and P3 from the WDM signal light. The communication device NE4 outputs the WDM signal light from which the optical signals P1 and P3 have been dropped to the next communication device NE.

[0054] <Network Management Method of the Embodiment> Next, a network management method of this embodiment will be described. Fig. 12 is a diagram illustrating a network management method according to the first embodiment. As shown in Figs. 3 and 12, the communication device NE1 receives a WDM signal light including an optical signal P11 and an optical signal P13. The optical signal P11 is an optical signal that is dropped by the communication device NE4, and the optical signal P13 is an optical signal that is dropped by the communication device NE3. Guard bands are provided in the slots SL1 and SL6 on both sides of the optical signal P11. Guard bands are provided in the slots SL11 and SL16 on both sides of the optical signal P13.

[0055] The communication device NE1 adds an optical signal P12 to the received WDM signal light and multiplexes it. The optical signal P12 is an optical signal that is dropped by the communication device NE4, similar to the optical signal P11. Therefore, when the communication device NE1 adds the optical signal P12 to the WDM signal light, the add control unit 11 controls the communication device NE1 so that the optical signals P11 and P12 dropped by the communication device NE4 are added adjacent to the wavelength band between the guard bands G11 and G12. As a result, the wavelength cross-connect function unit 120 of the communication device NE1 selects the wavelength band into which the optical signal P12 is added and switches it. Therefore, the wavelength cross-connect function unit 120 opens the wavelength band between the guard bands G11 and G12. The wavelength multiplexing / demultiplexing function unit 130 and the transponder function unit 140 add the optical signal P12 adjacent to the wavelength band between the guard bands G11 and G12. The communication equipment NE1 adds the optical signal P12 and outputs the multiplexed WDM signal light to the communication equipment NE2.

[0056] The communication device NE2 receives WDM signal light including optical signals P11, P12, and P13. The communication device NE2 adds the optical signal P14 to the received WDM signal light to multiplex it. The optical signal P14 is an optical signal that is dropped by the communication device NE3, similar to the optical signal P13. Therefore, when the communication device NE2 adds the optical signal P14 to the WDM signal light, the add control unit 11 controls the communication device NE2 to add the multiple optical signals P13 and P14 dropped by the communication device NE3 adjacent to the wavelength band sandwiched between the guard bands G13 and G14. As a result, the wavelength cross-connect function unit 120 of the communication device NE2 selects the wavelength band into which the optical signal P14 is added and switches it. Therefore, the wavelength cross-connect function unit 120 opens the wavelength band sandwiched between the guard bands G13 and G14. The wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 insert the optical signal P14 into a wavelength band sandwiched between guard bands G13 and G14. The WDM signal light includes optical signals P11 to P14 as shown in Fig. 3. The communication device NE2 outputs the multiplexed WDM signal light to the communication device NE3.

[0057] The communication device NE3 receives the WDM signal light including the optical signals P11 to P14. The communication device NE3 branches the optical signal P13 and the optical signal P14 from the WDM signal light. For example, the branching control unit 12 controls the communication device NE3 so that when the communication device NE3 branches the optical signals P13 and P14 from the WDM signal light, the branching control unit 12 controls the communication device NE3 to branch the optical signals P13 and P14 inserted into the wavelength band sandwiched between the guard bands G13 and G14 at the communication device NE3. As a result, the wavelength cross-connect function unit 110 of the communication device NE3 selects the wavelength band into which the optical signals P13 and P14 are branched and switches the selected wavelength band. The wavelength multiplexing / demultiplexing function unit 130 and the transponder function unit 140 branch the optical signals P13 and P14 from the wavelength band sandwiched between the guard bands G13 and G14. The communication equipment NE3 branches the optical signals P13 and P14, separates the wavelengths of the optical signals, and outputs the resulting WDM signal light to the communication equipment NE4.

[0058] The communication device NE4 receives a WDM signal light including optical signals P11 to P12. The communication device NE4 branches the optical signal P11 and the optical signal P12 from the WDM signal light. For example, the branching control unit 12 controls the communication device NE4 so that, when the communication device NE4 branches the optical signals P11 and P12 from the WDM signal light, the multiplexing control unit 12 causes the communication device NE4 to branch the optical signals P11 and P12 inserted into the wavelength band sandwiched between the guard bands G11 and G12. As a result, the wavelength cross-connect function unit 110 of the communication device NE4 selects the wavelength band into which the optical signals P11 and P12 are branched and switches the selected wavelength band. The wavelength multiplexing / demultiplexing function unit 130 and the transponder function unit 140 branch the optical signals P11 and P12 from the wavelength band sandwiched between the guard bands G11 and G12. The communication equipment NE4 branches the optical signals P11 and P12, separates the wavelengths of the optical signals, and outputs the resulting WDM signal light to the next communication equipment NE.

[0059] Next, the effects of this embodiment will be described. In this embodiment, the network management device NMS controls the wavelength cross-connect functional units 110 and 120, as well as the wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140 of the communication equipment NE, to transmit optical signals branched by the same communication equipment NE together. This makes it possible to reduce the guard band between adjacent optical signals. Therefore, it is possible to improve the transmission capacity of the optical communication network.

[0060] (Embodiment 2) Next, a network management system according to a second embodiment will be described. The network management device NMS of this embodiment monitors the quality of a transmission line and estimates the quality of the transmission line. Then, the network management device NMS improves the transmission capacity by controlling the interval between adjacent optical signals based on the quality of the transmission line.

[0061] <WDM signal light in embodiment 2> Fig. 13 is a diagram for explaining the WDM signal light according to the embodiment 2. As shown in Fig. 13, the WDM signal light includes optical signals P21 to P24.

[0062] The optical signal P21 corresponds to slots SL2 to SL5. The optical signal P22 corresponds to slots SL5 to SL8. The optical signal P21 and the optical signal P22 are optical signals that are dropped by the same communication device NE. For example, the optical signal P21 and the optical signal P22 are optical signals that are dropped by the communication device NE4. The slots SL1 and SL9 are provided with guard bands G21 and G22. The optical signal P23 corresponds to slots SL11 to SL14. The optical signal P24 corresponds to slots SL14 to SL17. The slots SL10 and SL18 are provided with guard bands G23 and G24. The optical signal P23 and the optical signal P24 are optical signals that are dropped by the same communication device NE. For example, the optical signal P23 and the optical signal P24 are optical signals that are dropped by the communication device NE3. In the second embodiment, six slots can be reduced compared to the comparative example.

[0063] <Network management device configuration> Fig. 14 is a block diagram illustrating a network management device NMS according to embodiment 2. As shown in Fig. 14, the network management device NMS further includes a monitor unit 13, an estimation unit 14, a determination unit 15, and a signal interval control unit 16, in addition to a control unit 10, an insertion control unit 11, and a branch control unit 12. The monitor unit 13, the estimation unit 14, the determination unit 15, and the signal interval control unit 16 have functions as a monitor means, an estimation means, a determination means, and a signal interval control means, respectively.

[0064] The monitor unit 13 acquires monitor information. Specifically, the monitor unit 13 monitors at least one piece of monitor information related to the quality of the transmission line in at least one of the multiple communication devices NE. Specifically, the monitor information is information (monitor parameters) related to the state (quality, etc.) of optical communication, for example, a monitor value obtained by actually measuring OSNR (Optical Signal to Noise Ratio). Note that the monitor unit 13 may monitor, for example, the power of each wavelength band and the total power as the monitor information in the wavelength cross-connect functional units 110 and 120. In addition, the monitor unit 13 may monitor, for example, a quality factor (Q factor), a spectrum monitor value, a crosstalk (XT) monitor value, a state of polarization (SOP) monitor value, a differential group delay (DGD) monitor value, and a chromatic dispersion monitor value as the monitor information in the wavelength multiplexing / demultiplexing functional unit 130 and the transponder functional unit 140.

[0065] The estimation unit 14 estimates at least one penalty related to the quality of the transmission path. For example, the estimation unit 14 estimates at least one penalty for the receiving side by using monitored information. Here, the penalty is a value indicating the degree (amount of degradation) of an element (noise; distortion) that causes degradation of the transmission quality due to the transmission state of the optical signal. The penalty is, for example, a penalty converted into OSNR.

[0066] <Monitor values ​​and penalties> Fig. 15 is a graph illustrating an example of a monitor value VM1 of an OSNR actually measured by the monitor unit 13 of the network management device NMS according to the second embodiment and a value obtained by converting a penalty estimated by the estimator 14 into an OSNR. As shown in Fig. 15, the monitor unit 13 monitors the monitor value VM1 obtained by actually measuring the OSNR as monitor information. The estimator 14 estimates at least one penalty out of SOP fluctuation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity as a penalty. In Fig. 15, each penalty estimated by the estimator 14 is shown as a value converted into an OSNR.

[0067] The estimation unit 14 estimates the required value VR1 based on each penalty. Specifically, the estimation unit 14 calculates the required value VR1 by adding up the estimated penalties to the FEC threshold VF. The FEC threshold VF is a value obtained by converting the penalty in a transmission line in an unloaded state into an OSNR. The required value VR1 is an OSNR value required for preventing a communication error in the communication device NE on the receiving side. When the monitor value VM1 of the OSNR actually measured on the receiving side for an optical signal transmitted from the transmitting side falls below the required value VR1, a communication error occurs, and the optical signal cannot be transmitted properly. In FIG. 15, the actually measured monitor value VM1 has a margin of ΔV1 with respect to the required value VR1.

[0068] Fig. 16 is a graph illustrating an example of a monitor value VM2 of an OSNR actually measured by the monitor unit 13 of the network management device NMS according to the second embodiment and a value obtained by converting the penalty estimated by the estimator 14 into an OSNR. As shown in Fig. 16, the estimator 14 may estimate a penalty when the interval between optical signals in a wavelength band is changed. For example, narrowing the interval between optical signals increases the penalty of crosstalk.

[0069] Fig. 17 is a diagram illustrating a method for estimating a penalty by the estimator 14 of the network management device NMS according to the second embodiment. As shown in Fig. 17, the estimator 14 may estimate the penalty from a diagram showing the relationship between the interval (Δf) of optical signals in a wavelength band and the penalty converted into OSNR. The estimator 14 may also estimate the penalty using a lookup table showing the correspondence relationship with the interval of optical signals in a wavelength band. The estimator 14 calculates the required value VR2 so as to include the crosstalk penalty estimated when the interval of the optical signals is narrowed.

[0070] The judgment unit 15 judges whether it is possible to reduce the interval between adjacent optical signals in a wavelength band by using the monitor information and the penalty. OSNRThe determination unit 15 judges whether the difference ΔV2 obtained by subtracting the required OSNR value VR2 from the monitored value VM2 of the OSNR exceeds a predetermined value (margin) Mr. In this way, when the difference ΔV2 between the OSNR value VM2 actually measured by the monitor unit 13 and the required value VR2 obtained by adding up the penalties is equal to or greater than a predetermined threshold Mr, the determination unit 15 judges that it is possible to reduce the interval between adjacent optical signals in the wavelength band.

[0071] The signal interval control unit 16 controls the interval between adjacent optical signals in the wavelength band. For example, when it is determined that the interval between adjacent optical signals can be reduced, the signal interval control unit 16 controls each communication device NE to reduce the interval between the optical signals. OSNR When the difference ΔV2 obtained by subtracting the required OSNR value VR2 from the monitored value VM2 of the OSNR is equal to or larger than Mr, the signal interval control unit 16 reduces the interval between the optical signals when the communication device NE adds the optical signal to the WDM signal light. At that time, the signal interval control unit 16 may cause some of the adjacent optical signals to correspond to the same slot SL.

[0072] <How to judge the quality of the transmission path> Next, a management method according to the second embodiment will be described. First, a method for determining the quality of a transmission line will be described. Fig. 18 is a flow chart illustrating a method for determining the quality of a transmission line in the network management method according to the second embodiment.

[0073] As shown in step S21 of FIG. 18 and in FIG. 15, the monitor unit 13 of the network management device NMS monitors the monitor information. For example, the monitor unit 13 of the network management device NMS monitors the actually measured OSNR Get the monitor value VM1.

[0074] Next, as shown in step S22, the penalty is estimated. management The estimation unit 14 of the device NMS estimates the penalty, OSNR The required value VR1 converted into

[0075] Next, in step S23, the quality of the transmission path is determined. For example, management The determination unit 15 of the device NMS determines whether the monitor unit 13 has detected the OSNR The estimating unit 14 judges whether a difference ΔV1 between the monitored value VM1 and the penalty required value VR1 estimated by the estimating unit 14 is equal to or greater than Mr. If the difference ΔV1 is equal to or greater than Mr, the judging unit 15 judges that the quality of the transmission path is good and that it is possible to reduce the interval between adjacent optical signals.

[0076] <Method of controlling the interval between optical signals> Next, a method for controlling the intervals between optical signals in a transmission line will be described with reference to Fig. 19. Fig. 19 is a flow chart illustrating a method for controlling the intervals between optical signals in the network management method according to the second embodiment.

[0077] As shown in step S31 of FIG. 19, the monitor unit 13 of the network management device NMS monitors the monitor information. For example, the monitor unit 13 of the network management device NMS monitors the actually measured OSNR Get the monitor value of VM2.

[0078] Next, as shown in step S32, the penalty for reducing the interval between optical signals is estimated. For example, management An estimation unit 14 of the device NMS estimates a penalty when the interval between adjacent optical signals is reduced, OSNR The required value VR2 converted into

[0079] Next, in step S33, the quality of the transmission path when the interval between optical signals is reduced is determined. For example, management The determination unit 15 of the device NMS determines whether the monitor unit 13 has detected the OSNR It is determined whether the difference ΔV2 between the monitored value VM2 and the required value VR2 of the penalty estimated by the estimation unit 14 is equal to or greater than Mr.

[0080] Next, as shown in step S34, it is determined whether the interval between optical signals can be reduced. Specifically, if the difference ΔV2 is smaller than Mr, the determination unit 15 determines that the interval between optical signals cannot be reduced. In that case, the process ends.

[0081] On the other hand, in step S34, if the difference ΔV2 is equal to or larger than Mr, it is determined that the interval between optical signals can be reduced. In that case, as shown in step S35, the interval between optical signals is reduced. Specifically, the signal interval control unit 16 controls each communication device NE so as to reduce the interval between adjacent optical signals. In this way, the interval between optical signals in the transmission path can be controlled.

[0082] Next, the effects of this embodiment will be described. The network management device NMS of this embodiment uses monitor information and penalties to determine whether it is possible to reduce the interval between adjacent optical signals in a wavelength band, and when it is determined that it is possible to reduce the interval between optical signals, controls each communication device NE to reduce the interval between adjacent optical signals. This makes it possible to improve the transmission capacity.

[0083] Furthermore, when the difference ΔV2 between the monitor value VM2 of the OSNR actually measured by the monitor unit 13 and the required value VR2 obtained by converting the penalty into OSNR is equal to or greater than a predetermined threshold value Mr, it is determined that it is possible to reduce the interval between optical signals, thereby making it possible to improve the transmission capacity without degrading the quality of the transmission path.

[0084] The present invention has been described above with reference to the outline of the embodiment and the first and second embodiments, but the present invention is not limited to the outline of the embodiment and the first and second embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. For example, an embodiment that combines the configurations of the outline of the embodiment and the first and second embodiments is also included in the scope of the technical idea.

[0085] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

[0086] (Appendix 1) In an optical communication network having a plurality of communication devices connected by a transmission line that transmits a WDM signal light in which a plurality of optical signals are wavelength division multiplexed, a first communication device controls the first communication device so that the plurality of optical signals dropped by a second communication device are inserted adjacent to a wavelength band sandwiched between guard bands when the first communication device inserts the optical signal into the WDM signal light; controlling the second communication device so that, when the second communication device drops the optical signal from the WDM signal light, the second communication device drops a plurality of the optical signals inserted adjacent to the wavelength band sandwiched between the guard bands; A network management method comprising: (Appendix 2) the first communication device includes a first cross-connect unit that selects and switches the wavelength band into which the optical signal is to be added, and a transponder unit that transmits the optical signal to be added to the wavelength band; the second communication device includes a second cross-connect unit that selects and switches the wavelength band into which the optical signal is to be dropped, and the transponder unit that receives the dropped optical signal from the wavelength band; In the step of controlling the first communication device, Controlling the first cross-connect unit and the transponder unit; In the step of controlling the second communication device, Controlling the second cross-connect unit and the transponder unit. 2. A network management method as claimed in claim 1. (Appendix 3) monitoring at least one piece of monitor information related to a quality of the transmission path in at least one of the plurality of communication devices; estimating at least one penalty related to said quality; determining whether or not it is possible to reduce an interval between adjacent optical signals in the wavelength band using the monitor information and the penalty; controlling an interval between adjacent optical signals in the wavelength band; Further equipped with 3. A network management method according to claim 1 or 2. (Appendix 4) In the estimating step, As the penalty, at least one penalty among SOP variation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity is estimated; 4. A network management method as claimed in claim 3. (Appendix 5) In the estimating step, The penalty is estimated using a look-up table showing a correspondence relationship with the interval of the optical signal. 5. A network management method according to claim 3 or 4. (Appendix 6) In the step of determining, determining that it is possible to reduce the interval between adjacent optical signals in the wavelength band when a difference between the actually measured OSNR monitor value and a required value obtained by summing up the penalties is equal to or greater than a predetermined threshold value; A network management method according to any one of claims 3 to 5. (Appendix 7) In the step of controlling the interval between the optical signals, When the first communication device adds the optical signal to the WDM signal light, the spacing between the optical signals is reduced. A network management method according to any one of appendix 3 to 6. (Appendix 8) the wavelength band having a plurality of slots; In the step of controlling the interval between the optical signals, a part of the adjacent optical signals is assigned to the same slot; A network management method according to any one of claims 3 to 7. (Appendix 9) an optical communication network having a plurality of communication devices connected by a transmission line that transmits a WDM signal light in which a plurality of optical signals are wavelength division multiplexed; a network management device for managing the optical communication network; Equipped with The network management device an add control unit that controls a first communication device so that, when the first communication device adds the optical signal to the WDM signal light, the optical signals dropped by a second communication device are added adjacent to wavelength bands sandwiched between guard bands; a branching control unit that controls the second communication device so as to branch a plurality of the optical signals inserted adjacent to each other in the wavelength band sandwiched between the guard bands when the second communication device branches the optical signal from the WDM signal light; A network management system having: (Appendix 10) the first communication device includes a first cross-connect unit that selects and switches the wavelength band into which the optical signal is to be added, and a transponder unit that transmits the optical signal to be added to the wavelength band; the second communication device includes a second cross-connect unit that selects and switches the wavelength band into which the optical signal is to be dropped, and the transponder unit that receives the dropped optical signal from the wavelength band; the insertion control unit controls the first cross-connect unit and the transponder unit; The branch control unit controls the second cross-connect unit and the transponder unit. 10. The network management system of claim 9. (Appendix 11) The network management device A monitor unit that monitors at least one piece of monitor information related to a quality of the transmission path in at least one of the plurality of communication devices; an estimator for estimating at least one penalty related to said quality; a determination unit that determines whether or not it is possible to reduce an interval between adjacent optical signals in the wavelength band by using the monitor information and the penalty; a signal interval control unit that controls an interval between adjacent optical signals in the wavelength band; Further equipped with 11. A network management system according to claim 9 or 10. (Appendix 12) The estimation unit estimates at least one penalty among SOP variation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity as the penalty. 12. The network management system of claim 11. (Appendix 13) the estimation unit estimates the penalty using a lookup table indicating a correspondence relationship with the interval of the optical signal; 13. A network management system according to claim 11 or 12. (Appendix 14) the determination unit determines that it is possible to reduce the interval between adjacent optical signals in the wavelength band when a difference between a monitor value of the OSNR actually measured by the monitor unit and a required value obtained by summing up the penalties is equal to or greater than a predetermined threshold value. A network management system according to any one of claims 11 to 13. (Appendix 15) the signal interval control unit reduces an interval between the optical signals when the first communication device adds the optical signals to the WDM signal light; A network management system according to any one of appendixes 11 to 14. (Appendix 16) the wavelength band having a plurality of slots; the signal interval control unit causes adjacent portions of the optical signals to correspond to the same slot; A network management system according to any one of appendixes 11 to 15.

[0087] This application claims priority based on Japanese Patent Application No. 2021-047961, filed on March 22, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0088] 1 Network Management Systems 10 Control section 11 Insertion control section 12 Branch control section 13 Monitor section 14 Estimation part 15 Judgment section 16 Signal interval control section 100 Optical Communication Network 110 Wavelength cross-connect function unit 111 WSS Control Unit 112 Wavelength Selective Switch 120 Wavelength cross-connect function section 121 WSS Control Section 122 Wavelength Selective Switch 130 Wavelength multiplexing / demultiplexing function section 140 Transponder function unit 150 NE control section NE, NE1, NE2, NE3, NE4 Communication equipment NMS Network Management Device

Claims

1. In an optical communication network having a plurality of communication devices connected by a transmission line that transmits a WDM signal light in which a plurality of optical signals are wavelength division multiplexed, an insertion control means controls the first communication device so that, when a first communication device inserts the optical signal into the WDM signal light, the plurality of optical signals dropped by a second communication device are inserted adjacent to a wavelength band sandwiched between guard bands; a branching control means for controlling the second communication device so as to branch a plurality of the optical signals inserted adjacent to each other in the wavelength band sandwiched between the guard bands when the second communication device branches the optical signal from the WDM signal light; Equipped with A monitor means for monitoring at least one piece of monitor information related to the quality of the transmission path in at least one of the plurality of communication devices; an estimation means for estimating at least one penalty related to said quality; a determination means for determining whether or not it is possible to reduce an interval between adjacent optical signals in the wavelength band, using the monitor information and the penalty; a signal interval control means for controlling an interval between adjacent optical signals in the wavelength band; Further equipped with The monitor means measures an OSNR monitor value as the quality, the estimation means estimates a required value by summing an FEC threshold value obtained by converting the penalty in the transmission path in an unloaded state into the OSNR and a value obtained by converting at least one of the penalties of SOP fluctuation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity into the OSNR; the determining means determines that it is possible to reduce an interval between adjacent optical signals in the wavelength band sandwiched between the guard bands when a difference between the monitor value and the required value is equal to or greater than a predetermined threshold value. Network management device.

2. the first communication device includes a first cross-connect means for selecting and switching the wavelength band into which the optical signal is to be added, and a transponder means for transmitting the optical signal to be added to the wavelength band; the second communication device includes a second cross-connect means for selecting and switching the wavelength band into which the optical signal is to be dropped, and the transponder means for receiving the dropped optical signal from the wavelength band; the insertion control means controls the first cross-connect means and the transponder means; the branch control means controls the second cross-connect means and the transponder means; The network management device according to claim 1 .

3. the estimation means estimates the penalty using a look-up table indicating a correspondence relationship with the interval of the optical signal; The network management device according to claim 1 .

4. the signal interval control means reduces an interval between the optical signals when the first communication device adds the optical signals to the WDM signal light; The network management device according to claim 1 .

5. the wavelength band having a plurality of slots; the signal interval control means causes adjacent portions of the optical signals to correspond to the same slot; The network management device according to claim 1 .

6. a transmission line for transmitting WDM signal light in which a plurality of optical signals are wavelength-division multiplexed; When the optical signal is added to the WDM signal light, the optical signals branched by another communication device are added adjacent to wavelength bands sandwiched between guard bands; A communication device that branches a plurality of optical signals inserted adjacent to the wavelength bands sandwiched between the guard bands when branching the optical signal from the WDM signal light, At least one piece of monitor information relating to the quality of the transmission path is monitored by a monitor means in a network management device; said at least one quality related penalty being estimated by an estimation means in said network management device; a determination means in the network management device determines whether or not it is possible to reduce an interval between adjacent optical signals in the wavelength band using the monitor information and the penalty; an interval between adjacent optical signals in the wavelength band is controlled by a signal interval control means in the network management device; The monitor means measures an OSNR monitor value as the quality, The required value is estimated by adding an FEC threshold value obtained by converting the penalty in the transmission path in an unloaded state into the OSNR, and a value obtained by converting at least one of the penalties of SOP fluctuation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity into the OSNR, by the estimation means; the determining means determines that it is possible to reduce an interval between adjacent optical signals in the wavelength band sandwiched between the guard bands when a difference between the monitor value and the required value is equal to or greater than a predetermined threshold value; Communications equipment.

7. an optical communication network having a plurality of communication devices connected by a transmission line that transmits WDM signal light obtained by wavelength division multiplexing a plurality of optical signals; a network management device for managing the optical communication network; Equipped with The network management device an insertion control means for controlling a first communication device so that, when the first communication device inserts the optical signal into the WDM signal light, the first communication device inserts the plurality of optical signals dropped by a second communication device adjacent to a wavelength band sandwiched between guard bands; a branching control means for controlling the second communication device so as to branch a plurality of the optical signals inserted adjacent to each other in the wavelength band sandwiched between the guard bands when the second communication device branches the optical signal from the WDM signal light; having The network management device A monitor means for monitoring at least one piece of monitor information related to the quality of the transmission path in at least one of the plurality of communication devices; an estimation means for estimating at least one penalty related to said quality; a determination means for determining whether or not it is possible to reduce an interval between adjacent optical signals in the wavelength band, using the monitor information and the penalty; a signal interval control means for controlling an interval between adjacent optical signals in the wavelength band; Further equipped with The monitor means measures an OSNR monitor value as the quality, the estimation means estimates a required value by summing an FEC threshold value obtained by converting the penalty in the transmission path in an unloaded state into the OSNR and a value obtained by converting at least one of the penalties of SOP fluctuation, filter narrowing, crosstalk, DGD, chromatic dispersion, and nonlinearity into the OSNR; the determining means determines that it is possible to reduce an interval between adjacent optical signals in the wavelength band sandwiched between the guard bands when a difference between the monitor value and the required value is equal to or greater than a predetermined threshold value. Network Management Systems.

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