WO2015182070A1

WO2015182070A1 - Optical network management device and optical network management method

Info

Publication number: WO2015182070A1
Application number: PCT/JP2015/002531
Authority: WO
Inventors: 慎介藤澤; 竹下　仁士; 智之樋野; 田島　章雄
Original assignee: 日本電気株式会社
Priority date: 2014-05-27
Filing date: 2015-05-20
Publication date: 2015-12-03
Also published as: JPWO2015182070A1; JP6528770B2

Abstract

　Because, in a trunk optical network, it is difficult to maximize the efficiency of traffic accommodation as the whole of the optical network, this optical network management device has: a route search unit for accepting a plurality of traffic requests and determining, for each of the traffic requests, an optimum route between optical node devices; a wavelength path attribute determination unit for determining, for each of the traffic requests, the wavelength path attribute, including at least a modulation method, of a wavelength path for accommodating each of the traffic requests in the optimum route; and a wavelength path allocation unit for allocating the wavelength path to an optical frequency axis so that modulation methods of each of wavelength paths adjacent on the optical frequency axis are equal.

Description

Optical network management apparatus and optical network management method

The present invention relates to an optical network management apparatus and an optical network management method, and more particularly to an optical network management apparatus and an optical network management method used for an optical network using a wavelength division multiplexing method.

The backbone optical network provides a function of communicating the traffic of the client device via the optical fiber communication path connecting the bases according to the contract service quality (service class). Here, the backbone optical network receives a client signal via an interface between the node device and the client device. Then, after a plurality of client signals are multiplexed using various multiplexing methods, communication is performed via a larger capacity trunk transmission channel. The multiplexing scheme includes wavelength division multiplexing (WDM) scheme, time division multiplexing (TDM) scheme, and orthogonal frequency division multiplexing (OFDM scheme such as Orthogonal Division Division Multiplexing scheme).

In a backbone optical network, for example, a maximum capacity of several Tbps per optical fiber is realized by wavelength multiplexing using a large capacity optical link of 100 Gbps (Giga bit per second) class per channel using several tens of wavelengths. ing. At this time, in order to accommodate the optical path in all the available wavelength slots of the optical fiber and maximize the traffic accommodation efficiency of the entire optical network, it is necessary to appropriately assign the communication path and the used wavelength slot of each optical path. .

The communication path of wavelength path and the wavelength slot used are determined based on the allocation policy. Examples of route allocation policies include shortest route design and minimum hop count route design. Further, as a wavelength allocation policy, for example, a first-fit allocation method that allocates an optical path from an empty wavelength slot on the long wavelength side, a most used (Most used) that selects an empty wavelength slot with the highest usage rate in other paths. -Used) There is an allocation method.

An example of an optical network management apparatus that allocates such an optical path is described in Patent Document 1. The related optical path design apparatus described in Patent Document 1 uses a path and a wavelength as a reserved wavelength based on a demand plan for each ground, which is a combination of a node serving as a start point and a node serving as an end point, to which wavelengths are assigned in advance. make a reservation. When an optical path setting request is acquired, a reserved wavelength having the same ground as the optical path establishment request is searched and a wavelength is assigned.

The related optical path design apparatus has a resource management information database, database search means, empty wavelength search means, and database rewrite means. The resource management information database stores reserved wavelengths between nodes and “used” and “unused” status information. The database search means acquires the input optical path establishment request, and searches the resource management information database for a reserved wavelength having the same ground as the optical path establishment request. The free wavelength search means determines whether the reserved wavelength obtained by the database search means is suitable for the optical path establishment request, and if not, the empty wavelength search path on the route of the optical path establishment request is found from the resource management information database. Search for wavelength. The database rewriting means updates information corresponding to the path of the optical path establishment request in the resource management information database based on the empty wavelength obtained by the empty wavelength searching means.

By adopting such a configuration, according to the related optical path design apparatus, it is possible to suppress an increase in equipment even when a route and a wavelength are designed in advance.

Further, as a related technique, there is a technique described in Patent Document 2.

JP 2011-023981 A JP 2012-195787 A

In the backbone optical network, the Dense Wavelength Division Multiplexing Multiplexing Multiplexing Division method is in accordance with the International Telecommunications Union (ITU) Telecommunications Standardization Division (Telecommunication Standardization Sector: ITU-T). The optical frequency band is used. In the DWDM system, the entire available optical frequency band is subdivided by a fixed-width grid called a wavelength grid, and an optical signal of one wavelength channel is allocated within the grid width (ITU-T recommendation G.694.1). ).

ITU-T Recommendation G. The flexible frequency grid standardized by 694.1 has a configuration in which the minimum channel interval can be changed from 50 GHz to 12.5 GHz and the frequency slot width can be changed in units of 12.5 GHz. As a result, frequency slots having different widths can be assigned to each optical path, so that the optical frequency band assigned to the optical path can be minimized.

An example of a related backbone optical network system using such a flexible frequency grid is shown in FIG. The related trunk optical network system 500 includes optical node devices 711 to 718 related to the related optical network management device 600. The related optical network management device 600 and the related optical node devices 711 to 718 are connected to each other, and communicate information about the usage status of the optical network with each other.

FIG. 20 shows a flowchart for explaining the operation of the related optical network management apparatus 600. In response to one communication traffic request (step S701), the related optical network management apparatus 600 searches for the shortest path connecting the start node and the end node in the order of arrival (step S702), and determines the required number of wavelength slots. (Step S703). If there are empty spaces for the number of wavelength slots necessary for traffic accommodation (step S704 / YES), wavelength paths are allocated based on the above-mentioned First-Fit allocation method (step S706). If there is no available wavelength slot that can be assigned (step S704 / NO), a fiber is added to the required link (step S705). When wavelength path assignment is completed for all communication traffic requests (step S707 / NO), wavelength path setting information is notified to each optical node device (step S708), and wavelength path assignment is terminated.

However, in such a WDM optical network system using a flexible frequency grid, if the wavelength path is assigned based on the First-Fit assignment method as in the related optical network management apparatus 600 described above, the following problems occur. there were. That is, there are cases where wavelength paths having different number of wavelength slots or different modulation schemes are allocated so as to be adjacent to each other. In this case, communication quality degradation occurs in adjacent wavelength paths due to the nonlinear optical effect of the optical fiber.

Here, as shown in FIG. 21, it is possible to prevent deterioration in communication quality by inserting a small number of empty wavelength slots called guard bands between adjacent wavelength paths. However, in this case, it is necessary to insert a guard band for each location where the number of occupied wavelength slots or modulation schemes of adjacent wavelength paths are different. Therefore, there is a problem that the effective number of usable wavelength slots per optical fiber is reduced.

As described above, the backbone optical network has a problem that it is difficult to maximize the traffic accommodation efficiency of the entire optical network.

An object of the present invention is an optical network management apparatus and an optical network management that solve the above-described problem that in a backbone optical network, it is difficult to maximize the traffic accommodation efficiency of the entire optical network. It is to provide a method.

The optical network management apparatus of the present invention receives at least a plurality of traffic requests, and determines at least modulation of a path search unit that determines an optimum path between optical node apparatuses for each traffic request, and a wavelength path that accommodates the traffic requests in the optimum path, respectively. A wavelength path attribute determining unit that determines a wavelength path attribute including a method for each traffic request and a wavelength path that allocates a wavelength path on the optical frequency axis so that the modulation methods of the adjacent wavelength paths on the optical frequency axis are equal. And an allocation unit.

The optical network management method of the present invention receives a plurality of traffic requests, determines an optimum path between optical node devices for each traffic request, and includes a wavelength including at least a modulation method in each wavelength path that accommodates the traffic request in the optimum path. A path attribute is determined for each traffic request, and wavelength paths are allocated on the optical frequency axis so that the modulation schemes of adjacent wavelength paths on the optical frequency axis are equal.

According to the optical network management apparatus and the optical network management method of the present invention, traffic can be efficiently accommodated in the backbone optical network.

It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the optical node apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the optical communication system for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the request traffic for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the reachability of the signal light for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the setting result of the wavelength path | pass by the optical network management apparatus concerning the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 3rd Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows schematic structure of the optical communication system for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 3rd Embodiment of this invention. It is the schematic for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the metric value used in order to demonstrate the wavelength path setting result by the optical network management apparatus concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 4th Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows schematic structure of the optical communication system for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 4th Embodiment of this invention. It is the schematic which shows the setting result of the wavelength path by the optical network management apparatus concerning the 4th Embodiment of this invention. It is a figure which shows the metric value used in order to demonstrate the wavelength path setting result by the optical network management apparatus concerning the 2nd Embodiment of this invention. It is a figure which shows the reachability of the signal light for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 5th Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 5th Embodiment of this invention. It is the schematic which shows the setting result of the wavelength path by the optical network management apparatus which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the structure of the optical network management apparatus which concerns on the 6th Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 6th Embodiment of this invention. It is another flowchart for demonstrating operation | movement of the optical network management apparatus which concerns on the 6th Embodiment of this invention. It is a block diagram which shows schematic structure of the optical communication system for demonstrating the wavelength path setting result by the optical network management apparatus concerning the 6th Embodiment of this invention. It is the schematic which shows the setting result of the wavelength path by the optical network management apparatus which concerns on the 6th Embodiment of this invention. It is a figure which shows the reachability of the signal light for demonstrating the wavelength path setting result by the optical network management apparatus which concerns on the 6th Embodiment of this invention. 1 is a block diagram showing a schematic configuration of a related backbone optical network system. FIG. It is a flowchart for demonstrating operation | movement of the related optical network management apparatus. It is a figure which shows the example which allocated the wavelength path | route by the related optical network management apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration of an optical network management apparatus 100 according to the first embodiment of the present invention. The optical network management apparatus 100 includes a route search unit 110, a wavelength path attribute determination unit 120, and a wavelength path allocation unit 130.

The route search unit 110 receives a plurality of traffic requests and determines an optimum route between the optical node devices for each traffic request. The wavelength path attribute determining unit 120 determines, for each traffic request, a wavelength path attribute including at least a modulation scheme of the wavelength paths that respectively accommodate the traffic requests in the optimum route. Then, the wavelength path assigning unit 130 assigns the wavelength paths on the optical frequency axis so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.

With such a configuration, according to the optical network management device 100 of the present embodiment, the modulation schemes of the wavelength paths adjacent on the optical frequency axis are equal, so that the number of places where guard bands are inserted is minimized. can do. As a result, traffic can be efficiently accommodated in the backbone optical network.

Next, the optical network management method according to this embodiment will be described. In the optical network management method according to the present embodiment, first, a plurality of traffic requests are accepted, and an optimum path between optical node devices is determined for each traffic request. Subsequently, the wavelength path attributes including at least the modulation method of the wavelength paths respectively accommodating the traffic requests in the optimum route are determined for each traffic request. Then, the wavelength paths are allocated on the optical frequency axis so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.

Even in this case, the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal, and therefore the number of places where guard bands are inserted can be minimized.

As described above, according to the optical network management apparatus and the optical network management method of the present embodiment, traffic can be efficiently accommodated in the backbone optical network.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 2 shows the configuration of the optical network management apparatus 200 according to this embodiment. As shown in FIG. 2, the optical network management apparatus 200 includes a database unit 210, a traffic accommodation design unit 220, and a path allocation control unit 230.

The database unit 210 includes a traffic DB 211, a physical layer topology DB 212, a wavelength path management DB 213, and a pre-allocation wavelength path DB 214. On the other hand, the traffic accommodation design unit 220 includes a route search unit 221, a required wavelength slot number determination unit 222, a wavelength slot / fiber allocation determination unit 223, and a traffic allocation order determination unit 224. The path allocation control unit 230 is connected to each optical node device.

Here, the route search unit 221 corresponds to the route search unit 110 included in the optical network management device 100 according to the first embodiment, and the required wavelength slot number determination unit 222 corresponds to the wavelength path attribute determination unit 120, respectively. The wavelength slot / fiber allocation determining unit 223 and the traffic allocation order determining unit 224 as an allocation order determining unit are an example of the wavelength path allocation unit 130.

The traffic DB 211 stores traffic requests. The physical layer topology DB 212 records the physical arrangement of the optical communication network and the fiber connection relationship. The wavelength path management DB 213 records operating wavelength path setting information. The pre-assignment wavelength path DB 214 stores the wavelength path modulation method determined by the required wavelength slot number determination unit 222.

FIG. 3 shows a configuration of the optical node device 300 according to the present embodiment. As shown in the figure, the optical node device 300 includes a large granularity switching unit 310, a control unit 320, and optical transponder (TPND)

devices

331 and 332.

The large granularity switching unit 310 connects an optical transmission line and optical transponder (TPND)

devices

331 and 332, and switches a plurality of optical transmission lines in units of wavelength paths. The control unit 320 receives wavelength path assignment information that is a result of assigning wavelength paths from the path assignment control unit 230 provided in the optical network management apparatus 200. Based on the wavelength path allocation information, the operations of the large granularity switching unit 310 and the optical transponder (TPND)

devices

331 and 332 are controlled. The optical transponder (TPND)

devices

331 and 332 transmit and receive client signals via the optical transmission path.

Next, the operation of the optical network management apparatus 200 according to this embodiment will be described. FIG. 4 is a flowchart for explaining the operation of the optical network management apparatus 200 according to the present embodiment.

First, the optical network management apparatus 200 extracts one communication traffic request from the traffic DB 211 in the order of arrival (step S201). The route search unit 221 refers to the physical layer topology DB 212 and searches for the shortest route connecting the start point node and the end point node of the traffic request (step S202). Next, the required wavelength slot number determination unit 222 determines the number of wavelength slots and the modulation method based on the link quality of the shortest path as a search result (step S203), and stores the modulation method in the pre-assignment wavelength path DB 214. (Step S204). Here, the required wavelength slot number determined by the required wavelength slot number determining unit 222 may be recorded in the pre-assignment wavelength path DB 214. This operation is performed for all traffic requests (step S205).

Next, the traffic allocation order determination unit 224 determines the order of the optical frequency utilization efficiency of the wavelength path determined by the modulation method. Specifically, one piece of communication traffic is extracted from the pre-allocation wavelength path DB 214 in accordance with the order of the magnitudes related to the optical frequency utilization efficiency of the wavelength paths (step S206). Here, the optical frequency utilization efficiency of the wavelength path is a modulation scheme such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), a modulation method per wavelength, such as a modulation scheme per wavelength path. Capacity. For wavelength paths having the same optical frequency utilization efficiency, the number of wavelength slots necessary for accommodating traffic is further ordered, and extraction is performed according to the order. At this time, the traffic allocation order determination unit 224 may extract traffic by ordering the number of wavelength path hops, the communication distance, and the communication quality of the wavelength path.

Note that in order to reduce the number of occurrences of fragmentation in the optical frequency band, it is common to assign traffic in order from long-distance traffic or traffic with a large number of hops. For such traffic, it is desirable to adopt a modulation scheme (for example, BPSK, QPSK) having low optical frequency utilization efficiency in consideration of the reachability of light. Therefore, in such a case, it is possible to adopt a configuration in which traffic is extracted in the order of decreasing optical frequency utilization efficiency.

In response to the extracted traffic request, the wavelength slot / fiber allocation determining unit 223 checks whether there is a free wavelength slot necessary for establishing communication between the two base nodes (step S207). If there are not enough free wavelength slots (NO in step S207), the number of fibers is increased (step S208), and the wavelength path at this time is assigned to the empty wavelength slot (step S209). The above-described procedure (steps S206 to S209) is performed for all wavelength paths held in the pre-allocation wavelength path DB 214. That is, the wavelength slot / fiber assignment determining unit 223 assigns the wavelength paths to the wavelength slots adjacent on the optical frequency axis in the order described above. After the above procedure is completed for all the wavelength paths (step S210 / NO), the wavelength slot / fiber allocation determination unit 223 notifies the path allocation control unit 230 of the wavelength path allocation information.

The path assignment control unit 230 notifies the database unit 210 and the optical node device 300 of the wavelength path setting result (step S211). The control unit 320 included in the optical node device 300 changes the settings of the large granularity switching unit 310 and the optical transponder (TPND)

devices

331 and 332 based on the received notification of the wavelength path setting result.

Note that the route search unit 221 may search for a route with the minimum number of hops connecting the start point node and the end point node related to the traffic request, or a route with the best link quality.

As described above, the traffic allocation order determination unit 224 performs ordering with respect to the optical frequency utilization efficiency of the wavelength paths, and performs ordering with respect to the number of wavelength slots for the wavelength paths having the same optical frequency utilization efficiency. Thereafter, traffic requests are extracted in that order. Then, the wavelength slot / fiber assignment determining unit 223 assigns the wavelength path by, for example, the First-Fit method. By adopting such a configuration, it becomes possible to set the wavelength path so that the wavelength paths of the same modulation method and the number of wavelength slots are adjacent to each other. That is, since the wavelength path is assigned from the long wavelength side in order from the wavelength path having the same modulation method and then the wavelength path having the same number of wavelength slots, the adjacent wavelength path has the same modulation method and the same This is the number of wavelength slots. As a result, the number of wavelength bands occupied by the guard band can be reduced, and the traffic accommodation efficiency of the entire optical network can be maximized.

Next, wavelength path setting results by the optical network management apparatus 200 according to the present embodiment will be described with reference to FIGS. 5A to 5D. Here, as shown in FIG. 5A, an optical communication system in which six optical node devices 301 to 306 are connected by optical fiber transmission lines will be described as an example.

When six traffic requests as shown in FIG. 5B arrive in this optical communication system, the wavelength usage situation in the optical link between the optical node device 303 and the optical node device 304 will be described. As shown in FIG. 5C, the modulation method is used as an example depending on the number of hops of the communication path, but is not necessarily limited thereto.

As described above, when the related optical network management apparatus 600 assigns wavelength paths, the wavelength paths are assigned in the order of arrival of traffic requests, so that signal lights of different modulation schemes are adjacent to each other as shown in FIG. Placed in. As a result, it was necessary to arrange a guard band between adjacent signal lights in order to prevent deterioration in communication quality.

On the other hand, when the optical network management apparatus 200 according to the present embodiment allocates a wavelength path, the modulation system and the required number of wavelength slots are determined after searching for a route having the minimum number of hops for each traffic request. Then, by assigning wavelength paths in order from the modulation scheme with the smallest multilevel, signal light of the same modulation scheme is allocated so as to be adjacent as shown in FIG. 5D. As a result, the number of guard bands to be inserted can be reduced. As described above, according to the optical network management apparatus 200 according to the present embodiment, the traffic accommodation efficiency of the entire optical communication system can be improved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 6 shows a configuration of the optical network management apparatus 201 according to the present embodiment. As illustrated in FIG. 6, the optical network management apparatus 201 includes a database unit 210, a traffic accommodation design unit 220, and a path allocation control unit 230.

The database unit 210 includes a traffic DB 211, a physical layer topology DB 212, a wavelength path management DB 213, and an adjacent wavelength path metric DB 215. Here, the adjacent wavelength path metric DB 215 manages the weighting amount according to the modulation method of the adjacent wavelength path.

The traffic accommodation design unit 220 includes a route search unit 221, a required wavelength slot number determination unit 222, a wavelength slot / fiber allocation determination unit 223, and a wavelength path allocation metric calculation unit 225.

The wavelength path allocation metric calculation unit 225, as a wavelength path metric calculation unit, calculates an adjacent wavelength path metric for each wavelength slot using a weighting amount determined by a modulation method of adjacent wavelength paths on the optical frequency axis. Specifically, the value of the adjacent wavelength path metric is calculated by adding the weighting amount corresponding to each modulation method of the wavelength path adjacent to the empty wavelength slot for each link. The wavelength path allocation metric calculation unit 225 may add a weighting amount related to the optical frequency utilization efficiency of the adjacent wavelength path and the required number of wavelength slots to the adjacent wavelength path metric.

Next, the operation of the optical network management apparatus 201 according to this embodiment will be described. FIG. 7 is a flowchart for explaining the operation of the optical network management apparatus 201 according to this embodiment.

First, the optical network management apparatus 201 extracts one communication traffic request from the traffic DB 211 (step S201). In response to the extracted communication traffic request, the route search unit 221 searches for the shortest route connecting the start point node and the end point node (step S202). Next, the required wavelength slot number determination unit 222 determines the number of wavelength slots and the modulation method based on the link quality of the path of the search result (step S203). The wavelength slot / fiber allocation determination unit 223 checks whether there is an empty wavelength slot necessary for establishing communication between the two base nodes (step S207). If there are not enough empty wavelength slots (step S207 / NO), the number of fibers is increased (step S208).

Next, the wavelength path allocation metric calculation unit 225 refers to the adjacent wavelength path metric DB 215 and adds a weighting amount corresponding to each modulation method of the wavelength path adjacent to the empty wavelength slot for each link of the shortest path. Thereby, the value of the adjacent wavelength path metric when assigning the wavelength path to the empty wavelength slot is calculated. At this time, the wavelength slot / fiber assignment determining unit 223 assigns the wavelength path to the wavelength slot in which the adjacent wavelength path metric is optimal. For example, a wavelength path is assigned to an empty wavelength slot having a minimum adjacent wavelength path metric (step S212).

After the above procedure is completed for all wavelength paths held in the traffic DB 211 (step S210 / NO), the wavelength slot / fiber allocation determination unit 223 notifies the path allocation control unit 230 of the wavelength path allocation information. The path allocation controller 230 notifies the wavelength path allocation information to the database unit 210 and the optical node device 300 (step S211).

Note that the weighting amount managed by the adjacent wavelength path metric DB 215 can be obtained from a transmission simulation result or a transmission experiment result. Also, a metric may be defined for the number of wavelength slots of adjacent wavelength paths.

Next, wavelength path setting results by the optical network management apparatus 201 according to the present embodiment will be described with reference to FIGS. 8A to 8C. Here, as shown in FIG. 8A, an optical communication system in which four optical node devices 301 to 304 are connected by optical fiber transmission lines will be described as an example.

Assume that there are empty wavelength slots SL401 to SL404 as shown in FIG. 8B in response to a traffic request on the optical link between the optical node device 301 and the optical node device 302. A method for calculating the adjacent wavelength path metric in this case will be described below.

The value of the adjacent wavelength path metric is set based on the modulation method of the wavelength path. Assuming three types of modulation schemes of QPSK, 8QAM, and 16QAM as modulation methods in adjacent wavelength paths, each metric value (weighting amount) when the adjacent wavelength slot is empty is defined as shown in FIG. 8C. For example, when the modulation method of the wavelength path to be allocated is 16QAM, the value of the adjacent wavelength path metric of the empty slot SL402 is obtained as follows. Since the left wavelength slot of the empty slot SL402 is a wavelength path of a 16QAM modulated signal and the right wavelength slot is an empty wavelength slot, the adjacent wavelength path metric value of the empty slot SL402 is 100 + 0 = 100 from FIG. 8C. As shown in FIG. 8B, since the adjacent wavelength path metric value of the empty slot SL402 among the empty wavelength slots SL401 to SL404 is minimized, according to the present embodiment, a traffic request is accommodated in the empty wavelength slot SL402. It will be.

Here, in the present embodiment, as shown in FIG. 8C, the metric value (weighting amount) is minimized when signal lights of the same modulation method are adjacent to each other. Also, as shown in FIG. 8B, adjacent empty wavelength slots exist for wavelength paths whose modulation schemes are QPSK, 8QAM, and 16QAM, respectively. Therefore, when an empty wavelength slot that minimizes the value of the adjacent wavelength path metric is selected, signal light of the same modulation scheme is assigned so as to be adjacent. As a result, in this case, the guard band to be inserted becomes unnecessary.

As described above, it is possible to set the wavelength path so that the wavelength paths according to the same modulation method are adjacent to each other by accommodating the traffic request in the empty wavelength slot in which the value of the adjacent wavelength path metric is the smallest. . Therefore, according to the optical network management apparatus 201 according to the present embodiment, the number of wavelength bands occupied by the guard band can be reduced, and the traffic accommodation efficiency of the entire optical network can be maximized.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 9 shows the configuration of the optical network management apparatus 202 according to this embodiment. As illustrated in FIG. 9, the optical network management apparatus 202 includes a database unit 210, a traffic accommodation design unit 220, and a path allocation control unit 230.

The database unit 210 includes a traffic DB 211, a physical layer topology DB 212, a wavelength path management DB 213, an adjacent wavelength path metric DB 215, and a wavelength path allocation candidate DB 216. Here, the wavelength path allocation candidate DB 216 holds the allocation of wavelength slots that realize the minimum value and the minimum value of the adjacent wavelength path metric for the path obtained by the path search unit 221.

Next, the operation of the optical network management apparatus 202 according to this embodiment will be described. FIG. 10 is a flowchart for explaining the operation of the optical network management apparatus 202 according to this embodiment.

First, the optical network management apparatus 202 extracts one communication traffic request from the traffic DB 211 (step S201). In response to the extracted communication traffic request, the route search unit 221 searches for the shortest route connecting the start point node and the end point node (step S202). Next, the required wavelength slot number determination unit 222 determines the number of wavelength slots and the modulation method based on the link quality of the shortest path (step S203).

Next, the wavelength path allocation metric calculation unit 225 refers to the adjacent wavelength path metric DB 215 to determine the weighting amount corresponding to each modulation method of the wavelength path adjacent to the empty wavelength slot for establishing communication in the shortest path. Add for each link. Thereby, the value of the adjacent wavelength path metric when assigning the wavelength path to the empty wavelength slot is calculated. Then, the minimum value of the adjacent wavelength path metric and the wavelength slot allocation when the minimum value is reached are stored in the wavelength path allocation candidate DB 216 (step S213).

At this time, it is determined whether the modulation method or the number of wavelength slots of the wavelength paths accommodated in the adjacent wavelength slots is the same in the empty wavelength slot in which the adjacent wavelength path metric is minimum (step S214). When the modulation method or the number of wavelength slots of the wavelength paths accommodated in the adjacent wavelength slots are different (step S214 / NO), the same operation is performed on the next shortest path (step S215 / YES). Thereby, a search is made for an empty wavelength slot in which the wavelength paths accommodated in the adjacent wavelength slots have the same modulation scheme or the same number of wavelength slots.

When there are no route re-search candidates (step S215 / NO), wavelength paths are assigned to the wavelength slot in which the adjacent wavelength path metric value for each route is minimum (step S218). If there is no empty wavelength slot (step S216 / NO), fiber addition is performed on the link with no empty wavelength slot among the shortest path links (step S217).

After the above procedure (steps S201 to S218) is completed for all the wavelength paths held in the traffic DB 211 (step S210 / NO), the wavelength slot / fiber allocation determination unit 223 transmits the wavelength path allocation information to the path allocation control unit. 230 is notified. The path allocation control unit 230 notifies the wavelength path allocation information to the database unit 210 and the optical node device 300.

For complex networks, an upper limit value for the number of route re-searches may be set in advance in order to shorten the wavelength path design time. In order to prevent the modulation scheme from being changed due to a difference in communication quality for each path, an upper limit value may be provided for the path length.

Next, the setting result of the wavelength path by the optical network management apparatus 202 according to the present embodiment will be described with reference to FIGS. 11A to 11D. Here, as shown in FIG. 11A, an optical communication system in which four optical node devices 301 to 304 are connected by optical fiber transmission lines will be described as an example. Here, in response to a traffic request on the optical link between the optical node device 301 and the optical node device 303, there are two paths R401 and R402 as wavelength path allocation candidates.

Since the two paths R401 and R402, which are wavelength path allocation candidates, both have two or more hops, assuming that the reachability of the signal light is as shown in FIG. 11D, the QPSK method is adopted as the modulation method. The path R401 is the shortest path, but the modulation method of the wavelength path adjacent to the empty wavelength slot SL401 in the optical link between the optical node apparatus 301 and the optical node apparatus 302 is 16QAM as shown in FIG. 11B. Therefore, when the modulation method of the wavelength path to be allocated is QPSK, it is necessary to insert a guard band (Guard Band). As a result, the traffic accommodation efficiency is reduced.

On the other hand, in the empty wavelength slot SL402, since the wavelength path to be allocated and the modulation system of the adjacent wavelength slot are both QPSK systems, a guard band (Guard Band) is unnecessary.

Here, when the modulation method in the adjacent wavelength path is the QPSK method or the 16QAM method, and when the adjacent wavelength slot is empty, each metric value (weighting amount) can be defined as shown in FIG. 11C. . In this case, the value of the adjacent wavelength path metric is 1100 in the empty wavelength slot SL401 and 100 in the empty wavelength slot SL402. Therefore, according to the optical network management apparatus 202 of this embodiment, a traffic request is accommodated in the empty wavelength slot SL402.

As described above, in the optical network management apparatus 202 of this embodiment, the route search unit 221 determines a plurality of optimum routes. A wavelength path allocation metric calculation unit 225 as a wavelength path metric calculation unit calculates adjacent wavelength path metrics for the plurality of optimum paths. Then, the wavelength slot / fiber allocation determination unit 223 as the wavelength path allocation unit sets the wavelength path to the wavelength slot for which the adjacent wavelength path metric is optimal so that the modulation methods of the adjacent wavelength paths on the optical frequency axis are equal. Is assigned. Therefore, according to the optical network management apparatus 202 according to the present embodiment, the number of wavelength bands occupied by the guard band (Guard Band) can be reduced, and the traffic accommodation efficiency of the entire optical network can be maximized.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIG. 12 shows the configuration of the optical network management apparatus 203 according to this embodiment. As illustrated in FIG. 12, the optical network management apparatus 203 includes a database unit 210, a traffic accommodation design unit 220, and a path allocation control unit 230.

The database unit 210 includes a traffic DB 211, a physical layer topology DB 212, a wavelength path management DB 213, a pre-allocation wavelength path DB 214, and a wavelength path allocation region DB 217. The wavelength path allocation area DB 217 records the distinction of empty slot areas to which wavelength paths are allocated according to the wavelength path modulation scheme and the required number of slots.

The traffic accommodation design unit 220 further includes a region slot number determination unit 226 as a wavelength path allocation region setting unit. The area slot number determination unit 226 determines a slot area (wavelength path allocation area) to which a wavelength path is allocated according to the type of traffic request.

Next, the operation of the optical network management apparatus 203 according to this embodiment will be described. FIG. 13 is a flowchart for explaining the operation of the optical network management apparatus 203 according to the present embodiment.

First, the optical network management apparatus 203 extracts one communication traffic request from the traffic DB 211 (step S201). In response to the extracted communication traffic request, the route search unit 221 searches for the shortest route connecting the start point node and the end point node (step S202). Next, the required wavelength slot number determination unit 222 determines the number of wavelength slots and the modulation method based on the link quality of the shortest path (step S203), and holds it in the pre-assignment wavelength path DB 214 (step S204). This operation is performed for all traffic requests (step S205).

Next, the region slot number determination unit 226 as the wavelength path allocation region setting unit determines the distinction of the empty slot region of the wavelength path allocation destination according to the wavelength path attributes such as the number of wavelength slots and the modulation method (step S219). ) And recorded in the wavelength path allocation region DB 217. The wavelength slot / fiber allocation determination unit 223 checks whether there is an empty wavelength slot necessary for establishing communication in response to the extracted traffic request (step S207). If there are not enough free wavelength slots (step S207 / NO), after adding fibers (step S208), wavelength paths are assigned to the free wavelength slots in the wavelength path assignment region at this time (step S209). After the above-described procedure is completed for all wavelength paths held in the traffic DB 211 (NO in step S210), the wavelength slot / fiber allocation determination unit 223 notifies the path allocation control unit 230 of the wavelength path allocation information. The path allocation controller 230 notifies the wavelength path allocation information to the database unit 210 and the optical node device 300 (step S211).

In the above description, the area slot number determination unit 226 determines the slot area. However, the present invention is not limited to this, and a slot area determined in advance by the operator may be used.

Next, the wavelength path setting result by the optical network management apparatus 203 according to the present embodiment will be described with reference to FIG.

As described above, when the related optical network management apparatus 600 assigns wavelength paths, the wavelength paths are assigned in the order of arrival of traffic requests, so that signal lights of different modulation schemes are adjacent to each other as shown in FIG. Placed in. Therefore, in order to prevent deterioration in communication quality, it is necessary to arrange a guard band (Guard Band) between adjacent signal lights.

On the other hand, the optical network management apparatus 203 according to the present embodiment includes a wavelength path having a wavelength path attribute equal to the wavelength path attribute related to the wavelength path allocation area in an empty slot area (wavelength path allocation area) to which the wavelength path is allocated. Are assigned to each. For example, if the wavelength path attribute is a modulation method, a wavelength path allocation area is set for each type of modulation method. In this case, since the wavelength path allocation region to which the wavelength path is allocated differs depending on the modulation method of the wavelength path, the modulation method of the adjacent wavelength slot is different only at the boundary of the wavelength path allocation region. Therefore, the guard band (Guard Band) may be arranged only at the boundary of the wavelength path allocation region.

In the above description, the case where the wavelength path attribute is a modulation method has been described. However, the number of wavelength slots is used as the wavelength path attribute, and the wavelength path allocation area is set for each number of wavelength slots accommodating traffic. Also good. In addition, the division of the wavelength path allocation area may be changed again in response to a change in traffic request.

As described above, by setting the wavelength path allocation region, for example, it becomes possible to set the wavelength path so that the wavelength paths having the same modulation method are adjacent to each other. As a result, according to the optical network management apparatus 203 according to the present embodiment, the number of wavelength slots occupied by the guard band can be reduced, and the traffic accommodation efficiency of the entire optical network can be maximized.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. FIG. 15 shows the configuration of the optical network management apparatus 204 according to this embodiment. As illustrated in FIG. 15, the optical network management apparatus 204 includes a database unit 210, a traffic accommodation design unit 220, and a path allocation control unit 230.

The database unit 210 further includes a divided wavelength path management DB 218. The divided wavelength path management DB 218 manages route information and wavelength slot information of a plurality of wavelength paths that accommodate traffic requests.

The traffic accommodation design unit 220 includes a divided slot determination unit 227. The division slot determination unit 227 manages division of the number of wavelength slots when dividing the traffic request into a plurality of wavelength slots according to the state of the empty wavelength slots.

Next, the operation of the optical network management apparatus 204 according to this embodiment will be described. FIG. 16 is a flowchart for explaining the operation of the optical network management apparatus 204 according to this embodiment.

First, the optical network management device 204 extracts one communication traffic request from the traffic DB 211 (step S201). In response to the extracted communication traffic request, the route search unit 221 searches for the shortest route connecting the start point node and the end point node (step S202). Next, the required wavelength slot number determination unit 222 determines the number of wavelength slots and the modulation method based on the link quality of the shortest path (step S203).

Next, when accommodating the wavelength path, it is determined whether or not there is an empty wavelength slot that does not require insertion of a guard band (Guard Band) (step S220). When such an empty wavelength slot exists (step S220 / YES), a wavelength path is assigned to this empty wavelength slot (step S209).

On the other hand, when such an empty wavelength slot does not exist (step S220 / NO), the division slot determination unit 227 as the wavelength path division unit divides the wavelength path accommodating the traffic request into a plurality of division wavelength paths. That is, the division slot determination unit 227 searches for an empty wavelength slot that can accommodate the traffic request by dividing it into a plurality of wavelength paths (step S221). If such an empty wavelength slot exists (step S221 / YES), wavelength path allocation is performed (step S222). If it cannot be accommodated even if it is divided into a plurality of wavelength paths (step S221 / NO), a fiber is added to the link having no empty wavelength slot among the shortest path links (step S208).

Next, the above-described processing (step S221) of searching for an empty wavelength slot that is divided and accommodated into a plurality of wavelength paths will be further described based on the flowchart shown in FIG.

First, the case where there is no need to insert a guard band (Guard Band) and there are strips of free wavelength slots that can be allocated (step S223 / YES) will be described. In this case, the division slot determining unit 227 divides the wavelength path so as to match the maximum number of empty wavelength slots, and then assigns the empty wavelength slots (step S226). If there is an unaccommodated portion in the wavelength path for accommodating the traffic request, the above-described processing is performed again (step S227 / YES). When there is no unaccommodated portion (step S227 / NO), the division slot determination unit 227 notifies the path allocation control unit 230 of the wavelength path allocation information by wavelength path division (step S228).

On the other hand, if there is no available wavelength slot strip that can be allocated (step S223 / NO), the next shortest route is searched for (step S224). When such a route exists (step S224 / YES), the required number of wavelength slots and the modulation method are determined (step S225), and then wavelength path allocation is performed. If there is an unassigned wavelength path at the stage where all routes have been searched, a fiber is added to the necessary link on the shortest route.

Note that an upper limit value of the number of route re-searches may be set in advance. In order to prevent the modulation scheme from being changed due to a difference in communication quality for each path, an upper limit value may be provided for the path length. In addition, a restriction may be added to the number of divisions when the wavelength path is divided by the wavelength path division described above, and an upper limit value may be provided for the path length difference of the divided wavelength paths.

Next, the wavelength path setting result by the optical network management apparatus 204 according to the present embodiment will be described with reference to FIGS. 18A to 18C. Here, as shown in FIG. 18A, an optical communication system in which three optical node devices 301 to 303 are connected by optical fiber transmission lines will be described as an example. Here, there are two wavelength paths P401 and P402 in response to a traffic request on the optical link between the optical node device 301 and the optical node device 302.

Since the wavelength path P401 has one hop, assuming that the reachability of the signal light is as shown in FIG. 18C, the 16QAM method is adopted as the modulation method. On the other hand, since the wavelength path P402 has two hops, the QPSK method is used as the modulation method.

Considering a traffic request between the optical node device 301 and the optical node device 302, the wavelength path P401 (optical link 301: 302) does not have a sufficient number of free slots to accommodate the traffic request. (See FIG. 18B). In this case, it has been necessary to add a new optical fiber until now.

On the other hand, the optical network management apparatus 204 of this embodiment divides the wavelength path accommodating the traffic request into a plurality of divided wavelength paths, and sets the divided wavelength paths so that the modulation methods of the adjacent wavelength paths are equal. The configuration is assigned. As a result, the wavelength path P401 that accommodates part of the traffic request is assigned to the optical link that directly connects the optical node device 301 and the optical node device 302, and the rest is assigned to the wavelength path P402 of the optical link that passes through the optical node device 303. It becomes possible. At this time, signal light adopting the 16QAM modulation method is assigned to the empty slot SL401 of the wavelength path P401, and signal light adopting the QPSK modulation method is assigned to the empty slot SL402 of the wavelength path P402.

As described above, according to the optical network management apparatus 204 of the present embodiment, it is possible to effectively utilize strips of empty wavelength slots and arrange the wavelength paths that are the same modulation method so as to be adjacent to each other. Therefore, it is possible to reduce the number of occupied wavelength slots of the guard band (Guard Band), and to maximize the traffic accommodation efficiency of the entire optical network.

The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above-described embodiment. That is, the present invention can apply various modes that can be understood by those skilled in the art within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2014-109098 filed on May 27, 2014, the entire disclosure of which is incorporated herein.

100, 200, 201, 202, 203, 204 Optical

network management device

110, 221 Route search unit 120 Wavelength path attribute determination unit 130 Wavelength path allocation unit 210 Database unit 211 Traffic DB
212 Physical layer topology DB
213 Wavelength path management DB
214 Pre-allocation wavelength path DB
215 Adjacent wavelength path metric DB
216 Wavelength path allocation candidate DB
217 Wavelength path allocation region DB
218 Divided wavelength path management DB
220 traffic accommodation design unit 222 required wavelength slot number determination unit 223 wavelength slot / fiber allocation determination unit 224 traffic allocation order determination unit 225 wavelength path allocation metric calculation unit 226 area slot number determination unit 227 division slot determination unit 230 path

allocation control unit

300 , 301 to 306 Optical node device 310 Large granularity switching unit 320

Control unit

331, 332 Optical transponder (TPND) device 500 Related backbone optical network system 600 Related optical network management device 711 to 718 Related optical node device

Claims

Route search means for accepting a plurality of traffic requests and determining an optimum route between the optical node devices for each traffic request;
Wavelength path attribute determining means for determining, for each traffic request, a wavelength path attribute including at least a modulation scheme of the wavelength path respectively accommodating the traffic request in the optimum route;
An optical network management device comprising: wavelength path allocating means for allocating the wavelength path on the optical frequency axis so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.
The optical network management device according to claim 1,
The wavelength path allocating unit includes an allocation order determining unit,
The allocation order determining means determines the order of the optical frequency utilization efficiency of the wavelength path determined by the modulation method,
The wavelength network allocating unit allocates the wavelength paths to wavelength slots adjacent on the optical frequency axis according to the order.
The optical network management device according to claim 1,
The wavelength path allocation means includes wavelength path metric calculation means,
The wavelength path metric calculation means calculates an adjacent wavelength path metric for each wavelength slot using a weighting amount determined by a modulation method of adjacent wavelength paths on the optical frequency axis,
The optical network management device, wherein the wavelength path allocation unit allocates the wavelength path to a wavelength slot in which the adjacent wavelength path metric is optimal.
The optical network management device according to claim 3,
The route search means determines a plurality of the optimum routes,
The wavelength path metric calculation means calculates the adjacent wavelength path metric for each of the plurality of optimum paths,
The optical network management apparatus, wherein the wavelength path allocating unit allocates the wavelength path to a wavelength slot in which the adjacent wavelength path metric is optimal so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.
In the optical network management device according to claim 1 or 2,
A wavelength path allocation area setting means for setting a wavelength path allocation area for allocating the wavelength path on an optical frequency axis for each wavelength path attribute;
The optical network management apparatus, wherein the wavelength path allocation unit allocates a wavelength path having a wavelength path attribute equal to the wavelength path attribute related to the wavelength path allocation area to the wavelength path allocation area.
In the optical network management device according to any one of claims 1 to 5,
Wavelength path splitting means for splitting a wavelength path accommodating the traffic request into a plurality of split wavelength paths;
The optical network management device, wherein the wavelength path allocating unit allocates the divided wavelength path as the wavelength path on the optical frequency axis so that the modulation methods of the adjacent wavelength paths on the optical frequency axis are equal.
In the optical network management device according to any one of claims 1 to 6,
Path allocation control means and database means,
The path allocation control unit notifies the optical node device of wavelength path allocation information that is a result of the wavelength path allocation unit allocating the wavelength path,
The database means is an optical network management apparatus that stores the wavelength path allocation information.
Control means for receiving the wavelength path assignment information from the path assignment control means provided in the optical network management device according to claim 7;
Large-grain switching means for switching a plurality of optical transmission lines in units of the wavelength path;
A plurality of optical transponder devices that transmit and receive client signals via the optical transmission path,
The optical node device, wherein the control means controls the large granularity switching means and the optical transponder device based on the wavelength path allocation information.
Accepts multiple traffic requests, determines the optimal path between optical node devices for each traffic request,
Determining, for each traffic request, a wavelength path attribute including at least a modulation method of a wavelength path that accommodates the traffic request in the optimum route,
An optical network management method for allocating the wavelength path on the optical frequency axis so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.
In the optical network management method according to claim 9,
Determining the order of the optical frequency utilization efficiency of the wavelength path determined by the modulation method;
An optical network management method for allocating the wavelength paths to wavelength slots adjacent on the optical frequency axis according to the order.
In the optical network management method according to claim 9,
Calculate the adjacent wavelength path metric for each wavelength slot using the weighting amount determined by the modulation method of the adjacent wavelength path on the optical frequency axis,
An optical network management method for assigning the wavelength path to a wavelength slot in which the adjacent wavelength path metric is optimal.
The optical network management method according to claim 11,
Determining a plurality of said optimal routes;
Calculating the adjacent wavelength path metric for each of the plurality of optimum paths;
An optical network management method for allocating the wavelength path to a wavelength slot in which the adjacent wavelength path metric is optimal so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.
In the optical network management method according to claim 9 or 10,
A wavelength path allocation region for assigning the wavelength path is set on the optical frequency axis for each wavelength path attribute,
An optical network management method in which wavelength paths having a wavelength path attribute equal to the wavelength path attribute related to the wavelength path allocation area are respectively allocated to the wavelength path allocation area.
In the optical network management method according to any one of claims 9 to 13,
Dividing the wavelength path accommodating the traffic request into a plurality of divided wavelength paths;
An optical network management method for allocating the divided wavelength path as the wavelength path on the optical frequency axis so that the modulation schemes of the adjacent wavelength paths on the optical frequency axis are equal.