Optical node device and optical bandwidth allocation method

Abstract

To provide an optical network management device in an optical communication network using wavelength division multiplexing that improve utilization efficiency of communication networks.SOLUTION: An optical network management device 40041 includes wavelength selection information creating means for creating wavelength selection information, which is information about a wavelength selection process through which an optical path 40002 that accommodates information signals passes, for each optical path, and wavelength selection information notifying means for notifying an optical node device through which the optical path passes of the wavelength selection information.SELECTED DRAWING: Figure 5B

Description

[Technical Field]

[0001] The present invention relates to an optical network management device, and more particularly to an optical network management device in an optical communication network using wavelength division multiplexing. [Background technology]

[0002] The rapid expansion of mobile traffic and video services has created a demand for increased communication capacity in core networks. This demand for increased capacity is likely to continue in the future. In order to continuously expand communication capacity at limited costs, it is effective to increase network utilization efficiency by efficiently managing network resources.

[0003] In particular, in optical communication networks that handle extremely large amounts of information, it is important to efficiently use the optical frequency band, which is a communication resource. When using the optical frequency band in an optical communication network, it is necessary to consider the degradation of optical signal quality caused by various physical constraints in optical signal transmission. Physical constraints in this case include, for example, crosstalk between adjacent wavelength channels in wavelength-multiplexed optical signal transmission, and degradation of the optical signal-to-noise (S / N) ratio caused by optical fiber loss and optical noise added by optical amplifiers. Furthermore, the passband narrowing effect caused by passing through multiple optical bandpass filters (BPFs) also contributes to the aforementioned physical constraints. By considering and addressing these physical constraints, it is possible to improve the resource utilization efficiency in optical communication networks. As a result, the cost of transmitting large amounts of information bits can be reduced.

[0004] Patent Document 1 describes an example of a technique for suppressing the degradation of received signal quality caused by passing through a plurality of optical bandpass filters (BPFs) as described above.

[0005] In the method for setting the passband of a path described in Patent Document 1, for a path that passes through a large number of wavelength selective switches and incurs a large filtering penalty, the passband is set wide in the wavelength selective switches through which the path passes. On the other hand, for a path that passes through a small number of wavelength selective switches, the passband is set narrow in the wavelength selective switches through which the path passes. Then, a path that requires a wide passband is arranged next to a path that requires a narrow passband.

[0006] This configuration provides technology for constructing an optical transmission network that can improve the overall reception quality of signal light on each path without restricting transmission speed or the scale of the optical transmission network as much as possible.

[0007] Furthermore, Patent Document 2 describes a bandwidth-variable communication system that uses a modulation method with a large number of modulation levels and a corresponding narrow filter for optical communication paths with short transmission distances, and a modulation method with a small number of modulation levels and a corresponding wide filter for optical communication paths with long transmission distances, thereby making it possible to reduce the overall required spectral bandwidth and improve frequency utilization efficiency. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-098544 [Patent Document 2] International Publication No. 2011 / 030897 Summary of the Invention [Problem to be solved by the invention]

[0009] To improve the utilization efficiency of optical communication networks, it is desirable to minimize the optical frequency band per bit occupied by the information accommodated in the optical path. However, to avoid the degradation of optical signal quality due to the physical constraints mentioned above, an optical frequency band in excess of the optical frequency band required to transmit only the information bits is required. This additional optical frequency band is called a guard band. Because the guard band is not used for transmitting information bits, the more optical frequency band is required for the guard band, the lower the utilization efficiency of the optical communication network. Therefore, the fewer guard bands there are, the better.

[0010] The total amount of guard band required in an optical communication network varies depending on various factors, such as the types of optical paths available and the optical frequency bands assigned to those paths. Therefore, even if the hardware, such as optical nodes, optical fibers, and optical transceivers, is the same, it is possible to improve the utilization efficiency of the optical communication network by changing the operation and control methods of those devices. If the utilization efficiency of the optical communication network can be improved without changing the hardware, the cost of transferring large amounts of information bits can be reduced. For this reason, various optical path and optical frequency band allocation methods have been proposed.

[0011] An optical signal is transmitted from an optical signal source to an optical signal destination, passing through multiple optical nodes. The route from this optical signal source to the optical signal destination is called an optical path. An optical path usually passes through multiple optical nodes. Here, optical nodes are equipped with optical bandpass filters (BPFs) to perform wavelength selection processing to select wavelength-multiplexed optical signals. Therefore, the optical path passes through multiple optical BPFs. When passing through multiple optical BPFs, the passband is limited by the band narrowing effect, as mentioned above, and the optical signal quality deteriorates. To prevent deterioration of optical signal quality due to the band narrowing effect of the optical BPF, it is necessary to add the guard bands mentioned above in advance.

[0012] In the method for setting the passbands of paths described in the above-mentioned Patent Document 1, a path requiring a narrow passband is placed next to a path requiring a wide passband. Therefore, guard bands are added to both ends of the optical frequency band occupied by multiple adjacent optical paths. In this case, it is not possible to optimize the bandwidth of the guard band for each individual optical path, so unnecessary guard bands are added when viewed as an entire optical communication network including multiple optical paths. As a result, it is difficult to improve the utilization efficiency of the optical communication network.

[0013] As described above, in an optical communication network using wavelength division multiplexing, there has been a problem in that it is difficult to improve the utilization efficiency of the optical communication network due to the band narrowing effect in wavelength selection processing.

[0014] An object of the present invention is to provide an optical network management device that solves the above-mentioned problem that in an optical communication network using wavelength division multiplexing, it is difficult to improve the utilization efficiency of the optical communication network due to the band narrowing effect in wavelength selection processing. [Means for solving the problem]

[0015] The optical network management device of the present invention comprises a wavelength selection information creating means for creating wavelength selection information for each optical path, including bandwidth information of a protection band to be added to an optical signal on the optical path, and a protection band setting means for setting the bandwidth of the protection band for each optical path based on the wavelength selection information. [Effects of the Invention]

[0016] According to the optical network management device of the present invention, in an optical communication network using wavelength division multiplexing, even if a band narrowing effect occurs in wavelength selection processing, it is possible to improve the utilization efficiency of the optical communication network. [Brief explanation of the drawings]

[0017] [Figure 1A]1 is a block diagram showing a configuration of an optical network management device according to a first embodiment of the present invention. [Figure 1B] 1 is a block diagram showing a configuration of an optical node device according to a first embodiment of the present invention. [Figure 2A] FIG. 10 is a diagram for explaining a related optical frequency band allocation method. [Figure 2B] FIG. 10 is a diagram for explaining a related optical frequency band allocation method. [Figure 3] FIG. 2 is a block diagram showing the configuration of a related optical node. [Figure 4] FIG. 10 is a diagram for explaining the operation of a related optical BPF. [Figure 5A] FIG. 2 is a diagram for explaining allocation of an optical frequency band to an optical path by an optical frequency band allocation method according to the first embodiment of the present invention. [Figure 5B] FIG. 2 is a diagram for explaining allocation of an optical frequency band to an optical path by an optical frequency band allocation method according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a sequence diagram illustrating allocation of an optical frequency band to an optical path by the optical frequency band allocation method according to the first embodiment of the present invention. [Figure 7] 4 is a flowchart illustrating the operation of the optical network management device according to the first embodiment of the present invention. [Figure 8] FIG. 10 is a diagram schematically illustrating the configuration of an optical communication network that is the target of an optical network management device according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing the relationship between the number of optical nodes and the number of slots of a required guard band, which are registered in an optical network management device according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the results of calculating the total amount of guard bands determined by the optical frequency band allocation method according to the second embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing the results of calculating the accommodation rate of information signals in optical paths according to the optical frequency band allocation method according to the second embodiment of the present invention. [Figure 12] FIG. 10 is a diagram for explaining allocation of an optical frequency band to an optical path by an optical frequency band allocation method according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] [First embodiment] FIG. 1A is a block diagram showing a configuration of an optical network management device 100 according to a first embodiment of the present invention.

[0020] The optical network management device 100 has a wavelength selection information creation means 110 and a wavelength selection information notification means 120. The wavelength selection information creation means 110 creates wavelength selection information for each optical path, which is information related to the wavelength selection process through which the optical path carrying the information signal passes. The wavelength selection information notification means 120 notifies this wavelength selection information to the optical node devices through which the optical path passes.

[0021] As described above, the optical network management device 100 according to this embodiment is configured to generate wavelength selection information, which is information related to the wavelength selection process through which the optical path passes, for each optical path. This makes it possible to determine the optimal passband width of the optical path for each optical path according to the wavelength selection process. As a result, the optical network management device 100 according to this embodiment can improve the utilization efficiency of an optical communication network using wavelength division multiplexing, even when a band narrowing effect occurs in the wavelength selection process.

[0022] Here, the wavelength selection information described above can be information for each optical path regarding the bandwidth of a guard band that is added to the frequency band for the information signal.

[0023] Furthermore, the wavelength selection information may be information for each optical path regarding the number of optical bandpass filters (optical bandpass filters (BPFs)) through which the optical path passes. In this case, the optical network management device 100 may be configured to set optical paths so as to reduce the number of optical bandpass filters (optical BPFs) through which the optical path passes. Furthermore, the optical network management device 100 may preferentially set optical paths that pass fewer optical bandpass filters (optical BPFs).

[0024] The optical network management device 100 may further include a passband width determining unit that determines a passband width for each optical path in the wavelength selection process based on the wavelength selection information. The passband width is a bandwidth including the frequency band for the information signal and a guard band added to the frequency band.

[0025] When the optical path includes a first optical path and a second optical path that are adjacent to each other, the passband width determination means can be configured to select, as the guard band, one of the first guard band for the first optical path and the second guard band for the second optical path, which has a larger bandwidth. That is, the passband width determination means calculates the bandwidth of the first guard band that serves as the guard band for the first optical path whose center wavelength is a first wavelength. The passband width determination means also calculates the bandwidth of the second guard band that serves as the guard band for the second optical path whose center wavelength is a second wavelength that is adjacent to the first wavelength on the wavelength grid. The passband width determination means can then select, as the guard band, the one with the larger bandwidth.

[0026] 1B shows the configuration of an optical node device 200 that constitutes an optical network system together with the optical network management device 100. The optical node device 200 has a wavelength selection information receiving means 210, an optical bandpass filter (optical bandpass filter (BPF)) 220 with a variable passband width, and a control means 230.

[0027] The wavelength selection information receiving means 210 receives wavelength selection information from the wavelength selection information notifying means 120 included in the optical network management device 100. Based on this wavelength selection information, the control means 230 sets the passband width of the optical bandpass filter 220 for each optical path. Note that this passband width is a bandwidth including the frequency band for the information signal and a guard band added to the frequency band.

[0028] With this configuration, in the optical node device 200, the passband width of the optical bandpass filter 220 can be optimized for each optical path in accordance with the wavelength selection process.

[0029] Next, the optical frequency band allocation method according to this embodiment will be described.

[0030] In the optical frequency band allocation method of this embodiment, wavelength selection information, which is information related to the wavelength selection process through which an optical path carrying an information signal passes, is first created for each optical path. Then, based on this selection information, a passband width in the wavelength selection process is determined for each optical path.

[0031] Here, the wavelength selection information may be information for each optical path regarding the number of optical bandpass filters through which the optical path passes, or may be information for each optical path regarding the bandwidth of a guard band to be added to the frequency band for the information signal.

[0032] When an optical path includes a first optical path having a first center wavelength and a second optical path having a second center wavelength adjacent to the first wavelength on the wavelength grid, the optical frequency band allocation method according to this embodiment can further perform the following processing. That is, first, the bandwidth of a first guard band that serves as a guard band for the first optical path is calculated. Also, the bandwidth of a second guard band that serves as a guard band for the second optical path is calculated. Then, of the first guard band and the second guard band, the one with the larger bandwidth can be selected as the above-mentioned guard band.

[0033] Next, the optical frequency band allocation method according to this embodiment will be described in more detail.

[0034] First, a method for allocating optical frequency bands to related optical paths will be described.

[0035] As shown in Figures 2A and 2B, an example will be described in which a first optical path 10001 (Figure 2A) that passes through three nodes and a second optical path 10002 (Figure 2B) that passes through two nodes are set in an optical communication network consisting of three nodes. The amount of guard band given to the optical signal band is determined by the maximum number of optical nodes that can be passed, which is determined by the bit error rate. In the example shown in Figures 2A and 2B, the maximum number of optical nodes that can be passed is three. Note that the maximum number of nodes that can be passed is obtained in advance through a preliminary survey, and all optical paths can be set within a range that does not exceed the maximum number of nodes that can be passed.

[0036] 2A and 2B, the amounts of guard bands occupying the optical frequency bands allocated to the first optical path 10001 and the second optical path 10002 are equal. 2A and 2B show examples in which 6.25 GHz is set as one slot width, and guard band amounts of 12001 and 14001, each with a guard band amount of two slots width, are added. The amount of guard band to be added is realized by variably controlling the passband width of the optical band pass filter (BPF) included in each of the optical nodes 10011 to 10031.

[0037] Furthermore, the signal bands 11001 and 13001 in the first optical path 10001 and the second optical path 10002 are three slots wide. Here, when an optical signal passes through an optical node, it passes through only one optical BPF. Therefore, the first optical path 10001 passes through three optical BPFs, and the second optical path 10002 passes through two optical BPFs.

[0038] The configuration of the related optical node is shown in Figure 3. The related optical node 30003 is connected to a first optical fiber 30001 and a second optical fiber 30002, and includes an optical transceiver 30005 and an optical BPF 30006. The optical node 30003 performs the following three operations: sending (adding) an optical path from its own optical node to another optical node (optical path 30020), passing (cutting) an optical path through its own optical node (optical path 30010), or receiving (dropping) an optical path at its own optical node (optical path 30030). Here, the optical BPF 30006 is used to select one of these operations.

[0039] Next, the operation of an optical BPF will be explained using FIG. 4. An optical BPF has a passband narrowing effect as shown in the figure. That is, even if the passband widths and passband center optical frequencies of the optical BPFs provided in all optical nodes 20001 to 20003 are the same, the effective passbands 20011 to 20031 become narrower as the number of stages through which the optical BPF passes increases. In the example shown in FIG. 2A, the passband widths of the optical BPFs provided in optical nodes A, B, and C are the same. However, when the first optical path 10001 passes through multiple optical nodes, the effective passband widths 10101 to 10301 decrease. An increase in the number of stages through which the optical BPF passes is equivalent to an increase in the number of times the transfer function of the optical BPF is convoluted. Therefore, the passband narrowing effect of an optical BPF is a physical phenomenon that always accompanies an optical BPF.

[0040] As described above, as the number of optical nodes through which the first optical path 10001 shown in FIG. 2A passes increases, the effective passband widths of the optical BPFs included in the optical nodes 10011 to 10031 become smaller due to the band-narrowing effect of the optical BPFs. In the example shown in FIG. 2A, the optical BPF at node A can pass the entire optical frequency band, including the guard bands. At node B, the effective passband width 10201 of the optical BPF is smaller than the effective passband width 10101 when the first optical path 10001 passes through node A. Therefore, the guard bands of one slot at both ends of the assigned optical frequency band are blocked by the optical BPF. At this time, the signal band 11001 can pass through the optical BPF included in node B without being blocked, so no degradation of optical signal quality due to the band-narrowing effect of the optical BPF occurs. Next, when passing through node C, the effective passband width 10301 of the optical BPF becomes even smaller than when passing through node B. Therefore, the guard band blocked by the optical BPF increases to two slots on both ends of the assigned optical frequency band. In other words, in the example shown in FIG. 2A, the amount of guard band required increases by one slot every time the number of optical nodes through which the first optical path 10001 passes increases by one. However, as with passing through node B, the signal band 11001 is not blocked, so there is no degradation in optical signal quality due to the band narrowing effect of the optical BPF. In other words, since the number of nodes through which the first optical path 10001 passes is within the range of the maximum number of nodes that can be passed, there is no degradation in optical signal quality. Furthermore, since the number of nodes through which the first optical path 10001 passes is equal to the maximum number of nodes that can be passed, there is no waste in the allocation of guard bands.

[0041] The second optical path 10002 is similar to the first optical path 10001, and as shown in FIG. 2B, the guard band amount 14001 occupying the allocated optical frequency band is two slots, and the signal band is three slots. However, the number of optical nodes it passes through is different from that of the first optical path 10001. In other words, the second optical path 10002 passes through one fewer optical node than the first optical path 10001. As a result, the allocated guard band is one slot in excess at both ends of the signal band.

[0042] Next, allocation of optical frequency bands to optical paths by the optical frequency band allocation method of this embodiment will be described with reference to Figures 5A and 5B. The method of allocating optical frequency bands to optical paths according to this embodiment is characterized in that the amount of guard bands to be provided is variable depending on the number of optical nodes or optical BPFs through which the optical path passes.

[0043] The optical communication network configuration is similar to that shown in FIGS. 2A and 2B, except that each optical node acquires the amount of guard band to be set for the optical path to be processed from the optical network management device 40041.

[0044] The optical network management device 40041 manages all optical paths in the optical communication network. Therefore, information on which optical paths pass through which optical nodes is stored in the optical network management device 40041. Therefore, each of the optical nodes 40011 to 40031 can obtain information on how many nodes the optical path to be processed passes through from the optical network management device 40041.

[0045] Each of the optical nodes A (40011), B (40021), and C (40031) through which the first optical path 40001 passes is notified of wavelength selection information, which is information related to wavelength selection processing, by the optical network management device 40041. In the example shown in Fig. 5A, the optical network management device 40041 notifies the first optical path 40001 that it will pass through a total of three optical nodes, i.e., three stages of optical BPFs, between the transmitting and receiving ends. At the same time, each of the optical nodes A (40011), B (40021), and C (40031) is notified that the second optical path 40002 will pass through two stages of optical BPFs, as shown in Fig. 5B.

[0046] A first optical path 40001 and a second optical path 40002 pass through optical node A and optical node B. Optical node A and optical node B set guard bands 42001 of two slots at both ends of a signal band 41001 for the first optical path 40001, which passes through three nodes (Fig. 5A). On the other hand, for the second optical path 40002, which passes through only two nodes, they set guard bands 44001 of one slot at both ends of a signal band 43001 (Fig. 5B). Furthermore, only the first optical path 40001 passes through optical node C. Therefore, optical node C sets guard bands 42001 of two slots at both ends of the signal band only for the first optical path 40001, just like optical nodes A and B (Fig. 5A).

[0047] 2A and 2B, the method for allocating optical frequency bands to optical paths according to this embodiment can reduce the amount of guard bands assigned to the second optical path 40002, thereby eliminating excessive guard band allocation. This is because the optical nodes A, B, and C can learn the following information from the optical network management device 40041: that the first optical path 40001 passes through optical nodes A, B, and C, and the number of nodes it passes through is three, and that the second optical path 40002 passes through optical nodes A and B, and the number of nodes it passes through is two. As a result, each of the optical nodes A, B, and C can set the minimum necessary guard bands for the first optical path 40001 and the second optical path 40002.

[0048] Next, allocation of optical frequency bands to optical paths by the optical frequency band allocation method of this embodiment will be described in more detail with reference to Figures 6 and 7. Figure 6 is a sequence diagram, and Figure 7 is a flowchart.

[0049] First, the optical network management device allocates an optical frequency band for a signal based on an optical path setting request at time t1 ((1) in FIG. 6). The operation of the optical network management device at this time will be described with reference to FIG.

[0050] The optical network management device receives an optical path setting request (step S11) and searches for the shortest route connecting the optical signal sender and receiver according to the optical path setting request (step S12). Next, it searches for available, free optical frequency bands on the route obtained from the search results. If a free optical frequency band is found, it assigns this free optical frequency band to the optical path as an optical frequency band for the transport signal (step S13). Then, it determines an optical modulation method that can transmit over a distance equal to or greater than the optical path length (step S14). Note that if no route or free optical frequency band is found in the shortest route search (step S12) or free optical frequency band search, the optical path setting fails, and the optical path setting request cannot be fulfilled.

[0051] After the allocation of the optical frequency band for the signal (step S13) is completed, a search is made for optical path information adjacent to the optical frequency band of the optical path allocated here (step S15). If the signal source and destination of the adjacent optical path are the same as those of the optical path for the signal, and if the optical modulation method is also the same, the allocation of the optical frequency band for the guard band is not performed. In other cases, the allocation of the optical frequency band for the guard band is performed according to the method described using Figures 5A and 5B (step S16). When the allocation of the optical frequency band for the signal and the allocation of the optical frequency band for the guard band are completed, the allocation of the optical frequency band to the optical path is completed (step S17).

[0052] After that, the optical network management device notifies the optical nodes involved in the optical path set in the above process ((1) in Fig. 6) of the passing optical frequency bandwidth to be set in the optical BPF equipped in each optical node device ((2) in Fig. 6). Here, the optical nodes involved in the optical path are the transmitting optical node, the passing optical node, and the receiving optical node. Each optical node device involved in the optical path established in the above process ((1) in Figure 6) sets the passbandwidth of the built-in optical BPF based on the information notified from the optical network management device at time t2 ((3) in Figure 6). At time t3, the setting of the passbandwidth of the optical BPF equipped in each optical node device is completed. Here, the optical BPF equipped in each optical node device is configured to be able to change the optical frequency bandwidth in units of 6.25 GHz, which is the standardized optical frequency slot width. This optical frequency slot width has been standardized by the Telecommunication Standardization Sector (ITU-T) of the International Telecommunication Union (ITU) (ITU-T Recommendation G.694.1).

[0053] Each optical node device notifies the optical network management device that the setting of the passing optical frequency band has been completed ((4) in FIG. 6).

[0054] At time t4, the optical network management device confirms that all optical node devices involved in the optical path have completed setting the optical frequency bandwidth. After that, the optical network management device notifies the source optical node and destination optical node of the start of optical signal transmission and reception ((5) in Figure 6).

[0055] The source optical node and destination optical node that received the start notification at time t5 start transmitting and receiving optical signals, respectively, and notify the optical network management device of the start of transmission and reception ((6) in Figure 6). The optical network management device considers the optical path to be open by confirming at time t6 that transmission and reception of optical signals has started between the source optical node and destination optical node of the optical signal.

[0056] As described above, the optical network management device and optical frequency band allocation method of this embodiment can improve the utilization efficiency of an optical communication network using wavelength division multiplexing, even when a band narrowing effect occurs in wavelength selection processing.

[0057] Second Embodiment Next, a second embodiment of the present invention will be described. Fig. 8 schematically shows the configuration of an optical communication network 1000 that is the target of an optical network management device according to this embodiment. The configuration of the optical network management device according to this embodiment is the same as that according to the first embodiment (see Fig. 1A).

[0058] As shown in the figure, the optical communication network 1000 has a 4x4 mesh topology and is an optical communication network consisting of 16 optical nodes. In this embodiment, it is assumed that there is one connection request for an optical path with a signal bandwidth of 4 slots from each optical node to another optical node. That is, it is assumed that one optical path is requested for each different optical node, such as from optical node NE01 to NE02-NE16, from NE02 to NE01, NE03-NE16, and from NE03 to NE01, NE02, NE04-NE16, etc. Therefore, the total number of optical paths in the optical communication network 1000 shown in FIG. 8 is 240 (=16x15).

[0059] It is also assumed that the optical network management device has registered therein the relationship between the number of optical nodes through which an optical path passes and the required number of guard band slots, as shown in Fig. 9. Fig. 9 shows an example in which the required number of guard band slots differs when the number of optical nodes through which the path passes is three. Here, the required number of guard band slots is the guard band bandwidth, expressed as the number of slots, required to prevent degradation of optical signal quality due to the band narrowing effect caused by the optical BPF provided in each optical node device.

[0060] The optical network management device searches for an optical path that connects optical nodes NE01 and NE06 shown in Fig. 8 via the shortest route. One of these shortest routes is the route from NE01 to NE05 to NE06, which passes through three optical nodes. Therefore, in this embodiment, the required guard band is set to one slot, based on the example shown in Fig. 9. Note that each optical node device can learn, via the optical network management device, the relationship between the number of optical nodes through which the optical path passes and the number of slots in the required guard band, as shown in Fig. 9.

[0061] Furthermore, each of the optical nodes NE01, NE05, and NE06 involved in the optical path NE01->NE05->NE06 is notified by the optical network management device that the number of nodes through which the optical path NE01->NE05->NE06 passes is three. Therefore, according to this embodiment, the optical node devices NE01, NE05, and NE06 assign a bandwidth of one slot, which is the minimum guard band amount required when connecting the optical path NE01->NE05->NE06, to both ends of the signal band. As a result, each optical node device generates the optical path NE01->NE05->NE06, which has a bandwidth of six slots overall.

[0062] Similarly, the minimum necessary guard bands are set for other optical paths. For example, one of the shortest paths connecting NE01 to NE14 is NE01 → NE05 → NE09 → NE13 → NE14. In this case, the number of optical nodes through which the optical path passes is five, and therefore, based on the relationship in FIG. 9, the minimum necessary guard band amount to be provided is two slots. Therefore, the optical network management device according to this embodiment cooperates with the optical node devices NE01, NE05, NE09, NE13, and NE14 to generate the optical path NE01 → NE05 → NE09 → NE13 → NE14, to which a two-slot guard band is provided. The optical path NE01 → NE05 → NE09 → NE13 → NE14 has a signal band of four slots, and two guard bands are provided at each end of the signal band, resulting in an overall optical frequency band of eight slots.

[0063] In the optical communication network 1000 shown in Fig. 8, the amount of guard bands to be assigned can be determined according to the optical frequency band allocation method according to the present embodiment described above, and the total amount of guard bands required can be calculated. The results are shown in Fig. 10.

[0064] An example will be described in which the number of optical path requests between optical nodes is 1, i.e., the total number of all optical paths is 240. In the related optical frequency band allocation method described above, guard bands of two slots are assigned to both ends regardless of the number of optical nodes through which the optical path passes. Considering the possibility that another optical path may not be assigned to a wavelength band adjacent to the optical path, the total number of required guard bands is 608 slots. In contrast, when the optical frequency band allocation method according to this embodiment is applied, if the number of optical nodes through which the optical path passes is three or less, the number of assigned guard bands can be reduced from two slots to one slot, resulting in 180 slots. Therefore, it can be seen that this embodiment can reduce the total number of required guard bands to approximately one-third. As the number of optical path requests between optical nodes increases, the total number of required guard bands also increases. Comparing the related allocation method with the optical frequency band allocation method according to this embodiment, the optical frequency band allocation method according to this embodiment can reduce the number of guard bands by approximately 20% on average compared to the related allocation method. In this way, according to the optical frequency band allocation method of this embodiment, it is possible to minimize the amount of guard bands required for each optical path, and as a result, it is possible to obtain the effect of reducing the total amount of guard bands for all optical paths.

[0065] Fig. 11 shows the results of calculating the accommodation rate of information signals to optical paths in the optical communication network 1000 shown in Fig. 8. The horizontal axis represents the number of optical path requests between optical nodes, and the vertical axis represents the accommodation rate to optical paths.

[0066] Here, the accommodation rate refers to the ratio of the amount of information that can be successfully communicated by opening optical paths to the total amount of information that is desired to be communicated. Therefore, if all optical paths are successfully opened, the accommodation rate will be 100%. If the total amount of information that is desired to be communicated increases, there will be a shortage of wavelength bandwidth if the network wavelength bandwidth remains constant. Therefore, the more the total amount of information that is desired to be communicated (bits per second) increases, the greater the probability that an optical path will fail to be opened, and the accommodation rate will fall from 100%.

[0067] When the number of optical paths requested between optical nodes is 5, the related art will encounter a shortage of optical frequency resources, resulting in some information communication bits that cannot be accommodated in the optical paths. As a result, the accommodation rate will not be 100%. In contrast, the optical frequency band allocation method of this embodiment can reduce the amount of guard bands assigned to the optical paths, so that the accommodation rate does not decrease and all information communication bits can be accommodated in the optical paths. In other words, the optical frequency band allocation method of this embodiment can improve the utilization efficiency of the optical communication network.

[0068] As described above, the optical network management device and optical frequency band allocation method of this embodiment can improve the utilization efficiency of an optical communication network using wavelength division multiplexing, even when a band narrowing effect occurs in wavelength selection processing.

[0069] Third Embodiment Next, a third embodiment of the present invention will be described. In this embodiment, as shown in Fig. 12, a first optical path 90010 (center wavelength λ1) and a second optical path 90011 (center wavelength λ2) whose center wavelengths are adjacent to each other are multiplexed. The operation of the optical BPF provided in the optical network management device and optical node device according to this embodiment is the same as in the above-mentioned embodiments. That is, the optical network management device determines the amount of guard band to be added to the signal band and allocates an optical frequency band for each optical path.

[0070] 12, the first optical path 90010 passes through optical node A and optical node B, and therefore the number of optical BPFs it passes through is two. The relationship between the number of optical nodes it passes through and the number of required guard band slots is known in advance as shown in FIG. 9, and the minimum required number of guard band slots is one for the first optical path 90010. On the other hand, the second optical path 90011 passes through optical node A, optical node B, and optical node C, and therefore the number of optical BPFs it passes through is three. Therefore, in this embodiment, the minimum required number of guard band slots for the second optical path 900112 is set to be two.

[0071] In this way, the center wavelengths of the first optical path 90010 and the second optical path 90011 are adjacent to each other, and the number of guard band slots of the first optical path 90010 is different from the number of guard band slots of the second optical path 90011. In such a case, the number of guard band slots to be set midway between the center wavelength λ1 and the center wavelength λ2 is either 1, which is the number of guard band slots to be assigned to the first optical path 90010, or 2, which is the number of guard band slots to be assigned to the second optical path 90011.

[0072] In this case, the optical network management device according to this embodiment prioritizes the guard band with the larger number of slots. That is, the optical network management device according to this embodiment sets a guard band of two slots between the signal band 90021 of the first optical path 90010 and the signal band 9022 of the second optical path 90011. As a result, the signal band 90021 of the first optical path 90010 is not blocked by the effective passband width 90031 when the first optical path 90010 passes through optical node B. Furthermore, the signal band 90022 of the second optical path 90011 is not blocked by the effective passband width 90032 when the second optical path 90011 passes through optical node C.

[0073] In this manner, when an optical path includes adjacent first and second optical paths, the optical network management device of this embodiment can be configured to select, as the guard band (protection band), the one with the larger bandwidth between the first guard band (protection band) for the first optical path and the second guard band (protection band) for the second optical path. That is, the optical network management device of this embodiment calculates the bandwidth of the first guard band (protection band) that serves as the guard band (protection band) for the first optical path whose center wavelength is λ1 (first wavelength). Also, it calculates the bandwidth of the second guard band (protection band) that serves as the guard band (protection band) for the second optical path whose center wavelength is a second wavelength (λ2) that is adjacent to the first wavelength (λ1) on the wavelength grid. Then, the one with the larger bandwidth can be selected as the guard band (protection band).

[0074] As described above, the optical network management device and optical frequency band allocation method of this embodiment can improve the utilization efficiency of an optical communication network using wavelength division multiplexing, even when a band narrowing effect occurs in wavelength selection processing.

[0075] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0076] This application claims priority based on Japanese Patent Application No. 2016-031563, filed February 23, 2016, the disclosure of which is incorporated herein by reference in its entirety. [Explanation of symbols]

[0077] 100, 40041 Optical network management device 110 Wavelength selection information creation means 120 Wavelength selection information notification means 200 Optical Node Equipment 210 Wavelength selection information receiving means 220 Optical Bandpass Filter 230 Control Means 1000 Optical Communication Network 10001, 40001, 90010 First optical path 10002, 40002, 90011 Second optical path 10011~10031, 20001~20003, 40011~40031 optical nodes 10101~10301, 20011~20031, 90031, 90032 Effective passband width 11001, 13001, 41001, 90021, 9022 signal bands 12001, 14001, 42001, 44001 guard bands 30001 First Optical Fiber 30002 Second Optical Fiber 30003 Associated Optical Nodes 30005 Optical Transmitter / Receiver 30006 Optical BPF 30010, 30020, 30030 Optical Path

Claims

1. A control unit that sets the passband width of an optical filter for each optical path based on received wavelength selection information; an optical filter that operates for each of the optical paths within a passband width set by the control unit based on the wavelength selection information including bandwidth information of a guard band to be added to the optical signal on the optical path; Equipped with the wavelength selection information includes information for each optical path regarding the bandwidth of a guard band to be added to a frequency band corresponding to an optical signal; Optical node equipment.

2. The wavelength selection information includes information about the number of optical node devices that include optical filters through which the optical path passes. The optical node device according to claim 1 .

3. The control unit sets the optical filter so as to avoid quality degradation of the optical signal caused by the optical filter.

3. The optical node device according to claim 1.

4. The setting of the optical filter includes at least one of switching between drop-insert and pass-through of the optical path and changing the width of the guard band. The optical node device according to claim 1 .

5. a receiving unit that receives the wavelength selection information; The control unit sets a passband width of the optical filter through which the optical path passes based on the received wavelength selection information. The optical node device according to claim 1 .

6. When there is a first optical path having a first wavelength as its center wavelength and a second optical path having a second wavelength adjacent to the first wavelength on a wavelength grid as its center wavelength, The receiver receives wavelength selection information in which the protection band of the first optical path is set based on both wavelength selection information of the first optical path and wavelength selection information of the second optical path. The optical node device according to claim 5 .

7. When setting up an optical path between predetermined optical node devices, The receiving unit receives wavelength selection information corresponding to wavelength selection processing that is preferentially performed on optical paths with fewer filtering processes among the filtering processes that can be performed in the optical path setting. The optical node device according to claim 5 .

8. setting the passband width of the optical filter for each optical path based on the received wavelength selection information; operating the optical filter for each of the optical paths within a passband width set based on the wavelength selection information including bandwidth information of a guard band to be added to the optical signal on the optical path; the wavelength selection information includes information for each optical path regarding the bandwidth of a guard band to be added to a frequency band corresponding to an optical signal; Optical bandwidth allocation method.

Images