Network management device and path setting method

Abstract

In a multi-layer network, the control load in the upper layer network increases, and the utilization efficiency and reliability of the entire network decrease. [Solution] The network management device of the present invention comprises a logical path setting means for setting logical paths in a packet network, and a receiving means for receiving physical network information including route information and signal quality information of an optical network, and the logical path setting means extracts candidates for logical paths corresponding to physical paths in the optical network based on the route information, and determines a logical path from among the candidates based on the physical network information.

Description

Technical Field

[0001] The present invention relates to a network management device and a physical network management device, and more particularly to a network management device and a physical network management device used in a multi-layer network composed of a plurality of network layers including an optical network.

Background Art

[0002] Due to the rapid expansion of mobile traffic and video services, an increase in communication capacity in the core network is required. Such a demand for capacity expansion is likely to continue in the future. In order to continuously expand the communication capacity under limited costs, it is effective to improve the utilization efficiency of the network by efficiently operating the network resources. Also, it is important to enhance fault tolerance so that the provided services are not interrupted by the occurrence of unexpected faults.

[0003] In the current communication network, it is separated into a plurality of layers for each function and managed and operated respectively. Such a communication network can be considered as, for example, a multi-layer network that is a combination of a packet network in the upper layer and an optical network in the lower layer.

[0004] In the packet network in the upper layer, for example, IP (Internet Protocol) technology, MPLS (Multi-Protocol Label Switching) technology, etc. are used. The packet network is characterized in that it can utilize various communication protocols and can dynamically control the network by logically handling the network with a fine traffic granularity. By performing dynamic control, the network utilization efficiency can be improved.

[0005] In the lower-layer optical network, Wavelength Division Multiplexing (WDM) technology is used. The optical network is suitable for batch processing traffic in large granularities such as long-distance and high-capacity transmission. In addition, the optical network is characterized by the ability to directly obtain physical information such as the Signal to Noise Ratio (S / N ratio) of the communication line. On the other hand, due to the constraints of natural laws, there are fewer elements that can be dynamically controlled compared to the upper-layer network, and it is operated and managed almost statically. In a multi-layer network, when a failure occurs in the lower-layer network, it spreads to the upper-layer network, so the lower-layer network requires high reliability.

[0006] An example of a topology design device used for designing the network topology of such a multi-layer network is described in Patent Document 1. The topology design device of Patent Document 1 has a logical topology design means, a lower-layer path allocation means, a reliability evaluation means, and a lower-layer path accommodation change design means.

[0007] The logical topology design means designs the logical topology of the upper layer based on the topology information representing the physical connections of the network to be designed, the topology information representing which nodes are connected by logical links in the upper layer, and the information on the traffic volume generated between certain nodes. The lower-layer path allocation means allocates a lower-layer path indicating a path in the lower layer to the designed logical topology.

[0008] Further, when a failure occurs in any physical link or node in the lower layer, the reliability evaluation means evaluates whether the designed logical topology that indicates the conditions for ensuring reachability between each node in the upper layer satisfies the reliability conditions. Then, when the designed logical topology does not satisfy the reliability conditions, the lower layer path accommodation change design means changes the nodes passed through by the lower layer path without changing the end points of the assigned lower layer path, so as to design the accommodation change of the lower layer path to satisfy the reliability conditions.

[0009] With such a configuration, it is stated that even when a failure occurs in the physical link or node in the lower layer, the reachability between each node in the upper layer can be ensured, and it is possible to design a logical topology with high accommodation efficiency.

[0010] Also, as related technologies, there are the technologies described in Patent Documents 2 to 5.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0012] As described above, until now, only static operation and management have been performed in the lower-layer network. However, in recent years, with the advancement of digital coherent technology, the dynamic controllability has also improved in the optical network of the lower layer. Therefore, dynamic operation and management of the lower-layer network have become possible. By utilizing the characteristics of the network functions of the lower layer, it is expected to improve the utilization efficiency of the network.

[0013] On the other hand, in the upper layer such as IP and MPLS that constitute the multi-layer network, a huge amount of path control management processing is required, such as generating, deleting, and reconfiguring logical paths in response to communication traffic requests, and ensuring the connectivity of logical paths. In addition to such main processing, the management and control of the route setting information and transmission characteristic information of the optical paths in the optical network layer, which is a physical communication path, are also performed by collecting information from the lower layer, so the number of such processes is huge. At this time, if there is a discrepancy between the physical information of the lower layer collected by the upper layer and the current state of the lower layer, the utilization efficiency and reliability of the network will decrease.

[0014] As described above, in the multi-layer network including the upper-layer network and the lower-layer network, there has been a problem that the control load in the upper-layer network increases, and the utilization efficiency and reliability of the entire network decrease.

[0015] An object of the present invention is to provide a network management device and a physical network management device that solve the above-described problems.

Means for Solving the Problems

[0016] The network management device of the present invention includes a logical path setting means for setting a logical path in a packet network, and a receiving means for receiving physical network information including path information and signal quality information of an optical network. The logical path setting means extracts candidates for logical paths corresponding to physical paths in the optical network based on the path information, and determines a logical path from the candidates based on the physical network information.

[0017] The physical network management device of the present invention includes a physical path setting means for setting a physical path in an optical network, a network information storage means for storing physical network information including path information and signal quality information of the optical network, and a transmission means for transmitting the physical network information to a packet network management device that sets a logical path corresponding to the physical path based on the physical network information.

Advantages of the Invention

[0018] According to the network management device and the physical network management device of the present invention, the control load in the upper layer network can be reduced, and a multi-layer network with high utilization efficiency and reliability can be configured.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the directions of the arrows in the drawings are for illustrative purposes only and do not limit the directions of signals between blocks.

[0021] 〔First Embodiment〕 FIG. 1 is a block diagram schematically showing the configuration of a multi-layer network system 1000 according to the first embodiment of the present invention.

[0022] The multi-layer network system 1000 has a first network management device 1100 and a second network management device 1200. The first network management device 1100 sets a logical path in the first network layer (upper layer). The second network management device 1200 sets a physical path corresponding to this logical path in the second network layer (lower layer).

[0023] Here, as shown in FIG. 2, the second network management device 1200 includes a network information storage unit 1210 that stores physical network information including physical path information and transmission characteristic information of a second network layer (lower layer). Then, the first network management device 1100 sets a logical path based on this physical network information. Here, the first network management device 1100 can be configured to include an acquired information storage unit 1110 that stores the physical network information acquired from the second network management device 1200.

[0024] Thus, in the multi-layer network system 1000 of the present embodiment, the first network management device 1100 is configured to set a logical path based on the physical network information in the second network layer (lower layer). Therefore, it is possible to reduce the search target paths when the first network management device 1100 searches for logical paths. As a result, according to the multi-layer network system 1000 of the present embodiment, the control load in the first network layer (upper layer network) can be reduced, and a multi-layer network with high utilization efficiency and reliability can be configured.

[0025] Next, the operation of the multi-layer network system 1000 according to the present embodiment will be described with reference to the flowchart shown in FIG. 3.

[0026] Here, a multi-layer network hierarchically divided into an upper layer and a lower layer composed of five nodes (A to E) shown in FIG. 1 will be described as an example. The upper layer is a logical layer using IP technology or MPLS technology, and the lower layer is a physical layer using optical transmission technology.

[0027] In FIG. 1, nodes A to E physically form a ring network connected in a ring shape. At this time, the physical topology recognized by the lower-layer NMS (Network Management System) as the second network management device 1200 is a ring network. On the other hand, nodes A to E logically form a mesh network connected in a mesh shape. Therefore, the logical topology recognized by the upper-layer NMS as the first network management device 1100 is a mesh network.

[0028] Here, the case where a traffic request occurs between node C and node E (step S110 in FIG. 3) will be described. At this time, the upper-layer NMS and the lower-layer NMS search for the shortest path as the path connecting the nodes.

[0029] Since the lower layer is a ring network, the paths connecting node C and node E are two types: "C ←→ D ←→ E" or "C ←→ B ←→ A ←→ E". Therefore, the physical shortest path is physical path 1 consisting of "C ←→ D ←→ E".

[0030] Since the upper layer is a mesh network, there are a total of 16 paths connecting node C and node E under the condition that the same node is not passed through more than twice. Among these, the logical shortest path is logical path 1 consisting of "C ←→ E".

[0031] In physical path 1 "C ←→ D ←→ E", node D serves as the relay point, but in logical path 1 "C ←→ E", node C and node E are directly connected. The actual communication line (communication cable) coincides with physical path 1. However, since the upper-layer NMS can only recognize logical path 1, it cannot grasp that the path is relayed by node D.

[0032] However, as described above, the multilayer network system 1000 according to this embodiment is configured such that the upper-layer NMS (the first network management device 1100) sets a logical path based on physical path information (physical topology information). At this time, the upper-layer NMS can be configured to acquire in advance the physical topology information of the lower layer from the lower-layer NMS before executing path search (step S120).

[0033] Specifically, for the logical path connecting node C and node E, conditions are added, namely condition A "including node D and not including either node A or node B", or condition B "including node A and node B and not including node D". In this case, there is one logical path that satisfies condition A, which is "C ←→ D ←→ E", and there are two logical paths that satisfy condition B, which are "C ←→ A ←→ B ←→ E" and "C ←→ B ←→ A ←→ E", for a total of three logical paths. Therefore, by adding the above conditions, the candidates for the logical shortest path can be reduced from 16 to 3. As a result, according to the multilayer network system 1000 of this embodiment, the time for determining logical path 1 can be shortened.

[0034] In this way, the upper-layer NMS (the first network management device 1100) selects candidates for the logical path based on the physical path information (conditions A and B) (step S130). And a configuration can be adopted to determine the logical path from among these candidates for the logical path based on the physical path information and the transmission characteristic information (step S140). Here, the transmission characteristic information includes at least one of the optical signal-to-noise ratio (OSNR), the physical path length, and the signal quality.

[0035] On the one hand, the lower-layer NMS determines a physical path 1 for accommodating the logical path 1 determined by the upper-layer NMS (step S150). Here, since the upper-layer NMS and the lower-layer NMS use the same topology and the same path search method, the physical path 1 always coincides with the logical path 1. Therefore, it is not necessary to search for the physical path 1 again after searching for the logical path 1. As a result, the total time required to determine the logical path and the physical path necessary for establishing traffic communication can be shortened, and traffic communication can be established quickly.

[0036] Furthermore, when the logical path 1 is used as the operating system path (Primary path), the case of setting the redundant system path (Secondary path) will be specifically described.

[0037] In this case, when searching for the shortest logical path, the logical redundant path 1 "C ←→ D ←→ E" and the logical redundant path 2 "C ←→ A ←→ E" become candidates. However, on the physical topology, the logical path 1 "C ←→ E" and the logical redundant path 1 "C ←→ D ←→ E" are the same. Therefore, when the upper-layer NMS does not obtain the physical topology information, if judged only by the path length, there is a 50% probability that the logical redundant path 1 including node D will be selected as the redundant path.

[0038] Here, when a failure occurs in the physical path 1 "C ←→ D ←→ E", the logical path 1 "C ←→ E" also fails. At this time, consider the case where the upper-layer NMS tries to divert traffic to the logical redundant path 1 "C ←→ D ←→ E" predetermined before the failure occurs. In this case, the upper-layer NMS requests the lower-layer NMS to generate a physical path for accommodating the logical redundant path 1. However, as described above, on the physical topology, the logical path 1 "C ←→ E" and the logical redundant path 1 "C ←→ D ←→ E" are the same, so the lower-layer NMS fails to generate a physical redundant path 1 for accommodating the logical redundant path 1.

[0039] In this case, the upper-layer NMS will re-search for a redundant path different from the logical redundant path 1. As the shortest redundant path different from the logical redundant path 1 "C ←→ D ←→ E", there is the above-mentioned logical redundant path 2 "C ←→ A ←→ E". The logical redundant path 2 is also different from the logical path 1 "C ←→ E" in terms of the physical topology. Therefore, after the re-search, the lower-layer NMS will not fail to generate the physical redundant path.

[0040] However, according to the multi-layer network system 1000 of the present embodiment, since the upper-layer NMS performs logical path search after acquiring the physical topology information in advance, the re-search operation as described above can be prevented. Therefore, the probability of failure in network failure recovery when a physical failure occurs in the network can be reduced, and the reliability of the network can be improved.

[0041] In order to establish traffic communication, it is necessary to control the communication devices to establish communication after determining the logical path and the physical path. Therefore, in order to generate the physical path 1 "C ←→ D ←→ E", the lower-layer NMS checks the allocation status of the optical frequency slots in the optical fiber used for the physical path 1. At this time, the lower-layer NMS grasps the free status of the optical frequency slots in the optical network, which is the lower-layer network, by referring to the optical frequency slot information stored in advance in the network information storage unit 1210 (see FIG. 2).

[0042] Then, the lower-layer NMS determines optical transmission parameters such as the optical modulation method and the number of carriers according to the availability of optical frequency slots (step S160 in FIG. 3). At this time, the lower-layer NMS refers to the optical node information stored in the optical node information storage unit included in the network information storage unit 1210. Here, the optical node information is information regarding the specifications of the optical node device 1300 connected to the optical network. The lower-layer NMS controls the optical node device 1300 to configure a physical path based on the optical node information and the optical frequency slot information (step S170). That is, the lower-layer NMS controls the optical node device 1300 based on the determined optical transmission parameters. Thereby, the lower-layer NMS realizes the determined logical path and physical path and establishes traffic communication (step S180).

[0043] Specifically, the lower-layer NMS determines the number of optical frequency slots and the number of carriers to be assigned to the physical path using the previously acquired optical frequency slot information. The lower-layer NMS forms the physical path 1 by setting the optical transmission parameters, which are the determination results, in the optical node devices respectively provided by node C, node D, and node E related to the physical path 1. Thereby, traffic communication is established.

[0044] Next, a path setting method in the multi-layer network according to this embodiment will be described.

[0045] In the path setting method in the multi-layer network of this embodiment, first, before setting a logical path in the first network layer constituting the multi-layer network, the physical network information of the second network layer is acquired. Here, the second network layer is a network layer constituting the multi-layer network and is a network layer in which a physical path corresponding to the above-mentioned logical path is set. Further, the physical network information includes physical path information and transmission characteristic information. And in the path setting method in the multi-layer network of this embodiment, a logical path is set based on this physical network information.

[0046] At this time, candidates for the logical path can be selected based on the physical path information, and a configuration can be adopted in which the logical path is determined from among the candidates for the logical path based on the physical path information and the transmission characteristic information.

[0047] As described above, according to the multi-layer network system 1000 and the path setting method in the multi-layer network of the present embodiment, the control load in the upper-layer network can be reduced. Thereby, a multi-layer network with high utilization efficiency and reliability can be configured.

[0048] 〔Second Embodiment〕 Next, a second embodiment of the present invention will be described. FIG. 4 schematically shows the configuration of a multi-layer network system 2000 according to the present embodiment.

[0049] The configurations of the first network management device 1100 and the second network management device 1200 included in the multi-layer network system 2000 of the present embodiment are the same as those according to the first embodiment (see FIG. 2).

[0050] In the present embodiment, it is assumed that the logical path set by the first network management device 1100 and the physical path set by the second network management device 1200 are redundant paths for the operation system path. Then, the first network management device 1100 calculates, for each candidate for the logical path, the shared link cost, which is the cost of the logical path, from the shared link information of the redundant path included in the physical path information, and determines the logical path based on this shared link cost and the transmission characteristic information.

[0051] Here, the shared link information refers to a set of links that share the same risk, including not only logical links but also physical links, and refers to information regarding an extended Shared Risk Link Group. Hereinafter, the "shared link information" is simply referred to as "SRLG". Further, the transmission characteristic information includes at least one of an Optical Signal-to-Noise Ratio (OSNR), a physical path length, and a signal quality.

[0052] Next, the operation of the multi-layer network system 2000 according to the present embodiment will be described in detail with reference to FIG. 4.

[0053] In the present embodiment, as shown in FIG. 4, a network composed of 5 nodes described with reference to FIG. 1 in the first embodiment is taken as an example of a network having a configuration in which two such networks are connected. That is, the upper layer is a logical layer having a configuration in which two mesh networks each composed of 5 nodes are connected. The lower layer is a physical layer having a configuration in which two ring networks each composed of 5 nodes are connected. Hereinafter, a case where SRLG is used as physical path information (physical topology information) and OSNR is used as transmission characteristic information will be described as an example. Note that the description of operations common to the multi-layer network system 1000 according to the first embodiment is omitted.

[0054] The operation in which the first network management device 1100 calculates the shared link cost (SRLG cost) of a path will be described. The SRLG cost C for each path path can be obtained by summing the SRLG costs C link (SRLG) for each link constituting the path. That is, the SRLG cost C for each path path is calculated using the following formula (1). TIFF0007684248000001.tif27161

[0055] First, a case where the first network management device 1100 calculates the cost without obtaining the physical topology information will be described. Taking the operation of selecting a logical redundant path for the logical path 1 "C ←→ E" connecting node C and node E as an example, the search for the logical redundant path will be performed up to 4 hops for simplicity.

[0056] In the case of a 3-hop logical redundant path, the candidates are logical redundant path 1 "C ←→ A ←→ E", logical redundant path 2 "C ←→ B ←→ E", and logical redundant path 3 "C ←→ D ←→ E". In the case of a 4-hop, they are logical redundant path 4 "C ←→ A ←→ D ←→ E", logical redundant path 5 "C ←→ B ←→ D ←→ E", and logical redundant path 6 "C ←→ B ←→ A ←→ E". Since the number of hops is 5 or more hereafter, they are omitted here.

[0057] Let the SRLGs to which logical redundant paths 1 to 3 belong be SRLG-1 to SRLG-3 respectively. Referring to FIG. 4, for SRLG-1, the links with duplicates are the link "C ←→ A" for logical redundant path 1 "C ←→ A ←→ E" and logical redundant path 4 "C ←→ A ←→ D ←→ E". Also, for the link "A ←→ E", logical redundant path 1 "C ←→ A ←→ E" and logical redundant path 6 "C ←→ B ←→ A ←→ E" have duplicates.

[0058] For SRLG-2, the links with duplicates are logical redundant path 2 "C ←→ B ←→ E", logical redundant path 5 "C ←→ B ←→ D ←→ E", and logical redundant path 6 "C ←→ B ←→ A ←→ E" for the link "C ←→ B".

[0059] Also, for SRLG-3, the links with duplicates are logical redundant path 3 "C ←→ D ←→ E", logical redundant path 4 "C ←→ A ←→ D ←→ E", and logical redundant path 5 "C ←→ B ←→ D ←→ E" for the link "D ←→ E".

[0060] Here, regarding the logical redundant path 1, since the link "C ←→ A" has one link duplication, the SRLG cost is set to "+1". Also, since the link "A ←→ E" also has one duplication, the SRLG cost is set to "+1". Therefore, regarding the logical redundant path 1, the SRLG cost for the entire path is "+2". Similarly, regarding the logical redundant path 2, since the link "C ←→ B" has two link duplications, the SRLG cost is set to "+2". For the other link, that is, the link "B ←→ E" has no duplication, so the SRLG cost for the entire path is "+2".

[0061] Figure 5 summarizes these results for each candidate of the logical redundant path. For example, when the maximum hop count is "4", among the logical redundant paths 1 to 6, the ones with the minimum SRLG cost are the logical redundant paths 1 to 3.

[0062] Next, the case where the first network management device 1100 included in the multi - layer network system 2000 of the present embodiment acquires physical topology information and calculates the cost will be described. In this case, since the physical topology information assumes a redundant path, it becomes the condition B described in the first embodiment, that is, the condition of "including node A and node B and not including node D".

[0063] The logical redundant path effective against a physical failure of the network is either the logical redundant path 6 "C ←→ B ←→ A ←→ E" or the logical redundant path N "C ←→ B ←→ H ←→ G ←→ F ←→ A ←→ E" from the acquired physical topology information. Therefore, in the calculation of the SRLG cost, it becomes possible to exclude other invalid logical redundant paths from the process of cost calculation when the above - mentioned physical topology information is not acquired. As a result, the calculation process of the SRLG cost can be greatly simplified. In this case, for the SRLG cost, since the logical redundant path 6 and the logical redundant path N each have one duplication in the link "C ←→ B" and the link "A ←→ E", the SRLG cost for both is "+2".

[0064] As described above, when there are multiple candidate logical redundant paths with equal SRLG costs, the logical redundant path is determined using the OSNR information as transmission characteristic information. The upper layer NMS (the first network management device 1100) can know, by acquiring the OSNR information, that the OSNR required to realize the logical redundant path 6 is smaller than the OSNR required to realize the logical redundant path N. Therefore, the upper layer NMS can select the logical redundant path 6 as the redundant path of the logical path 1.

[0065] Note that since the required OSNR increases as the physical path length (physical path length) becomes longer, it is also possible to use the path length instead of the OSNR. Further, since the OSNR has a correlation with the Q value representing the signal quality, the Q value can also be used as the transmission characteristic information.

[0066] As described above, according to the multi-layer network system 2000 of the present embodiment, the control load in the upper layer network can be reduced, and a multi-layer network with high utilization efficiency and reliability can be configured.

[0067] 〔Third Embodiment〕 Next, a third embodiment of the present invention will be described. The configuration of the multi-layer network system according to this embodiment is the same as the configuration of the multi-layer network system 2000 according to the second embodiment shown in FIG. 4.

[0068] The second network layer (lower layer) constituting the multi-layer network system according to this embodiment is configured by an optical network. And the second network management device 1200 includes an optical frequency information storage unit that stores optical frequency slot information, which is the utilization status of optical frequency slots in the optical network (see FIG. 2).

[0069] The second network management device 1200 according to this embodiment calculates the number of optical frequency slots, which is the number of optical frequency slots required to configure a physical path as determined by transmission characteristic information. At this time, the first network management device 1100 obtains an optical frequency slot cost, which is the cost for securing the number of optical frequency slots determined for each candidate of the logical path based on this optical frequency slot information. Then, the first network management device 1100 is configured to determine a logical path based on the logical path cost, which is the sum of the optical frequency slot cost and the shared link cost (SRLG cost), and the transmission characteristic information.

[0070] Next, the operations of the first network management device 1100 and the second network management device 1200 according to this embodiment will be described in detail.

[0071] The lower-layer NMS as the second network management device 1200 stores in advance optical frequency slot information, which is the usage status of optical frequency slots in the optical network, in the optical frequency information storage unit. The usage status of the optical frequency slots is, for example, the situation shown in FIG. 6 for the link "B ←→ A" and the situation shown in FIG. 9 for the link "B ←→ H ←→ G ←→ F ←→ A". In these figures, each rectangular shape represents an optical frequency slot, and the white optical frequency slots indicate unused empty slots.

[0072] The lower-layer NMS can calculate the optical frequency slot cost in parallel with the upper-layer NMS as the first network management device 1100 performing SRLG cost calculation using the shared link information (SRLG) and the OSNR information. This is because the upper-layer NMS and the lower-layer NMS share topology information, so each can perform cost calculation independently and in parallel. Note that it is also possible for the upper-layer NMS to receive the optical frequency slot information from the lower-layer NMS and obtain the optical frequency slot cost by calculating the optical frequency slot cost.

[0073] As shown in Fig. 4, candidates for physical redundant paths are physical redundant path 1 "C ←→ B ←→ A ←→ E" and physical redundant path 2 "C ←→ B ←→ H ←→ G ←→ F ←→ A ←→ E". The lower-layer NMS pre-stores, as optical node information, that 4 optical frequency slots are required to realize physical redundant path 1 and 6 optical frequency slots are required to realize physical redundant path 2. The number of optical frequency slots required at this time is determined by transmission characteristic information such as the path length and OSNR held by the lower-layer NMS.

[0074] The utilization status of optical frequency slots in the link "B ←→ A" constituting physical redundant path 1 is as shown in Fig. 6, and the maximum number of consecutive free slots is 2 slots. Therefore, in order to realize physical redundant path 1 that requires 4 optical frequency slots, for example, as shown in Fig. 7, it is necessary to divide it into 2 consecutive 2-slot (2 slots × 2). Alternatively, as shown in Fig. 8, it is necessary to divide it into 1 consecutive 2-slot and 2 1-slot (2 slots × 1 + 1 slot × 2).

[0075] In the case shown in Fig. 7, since the number of times of dividing optical frequency slots is 1, the cost for securing the number of optical frequency slots (optical frequency slot cost) is set to "+1". Also, in the case shown in Fig. 8, since the number of times of dividing optical frequency slots is 2, the optical frequency slot cost becomes "+2".

[0076] On the other hand, the utilization status (free status) of optical frequency slots in the link "B ←→ H ←→ G ←→ F ←→ A" constituting physical redundant path 2 is as shown in Fig. 9, and the maximum number of consecutive free slots is 6 slots. Therefore, physical redundant path 2 can be realized without dividing the required 6 optical frequency slots. In this case, since the number of times of division required to secure the number of optical frequency slots is zero, the optical frequency slot cost is "0".

[0077] As described above, the optical frequency slot cost C for each link constituting the path linkBy summing up the (slots), the optical frequency slot cost C for each path can be obtained. That is, the optical frequency slot cost C for each path path can be obtained. That is, the optical frequency slot cost C for each path path can be calculated using the following formula (2). TIFF0007684248000002.tif27161

[0078] As the number of times of dividing the optical frequency slot increases, the probability of quality degradation in optical transmission increases due to timing deviations such as skew between the divided optical frequency slots. Therefore, it is better that the number of times of dividing the optical frequency slot is smaller. Thus, in the above example, the physical redundant path 1 is disadvantageous because its optical frequency slot cost is larger than that of the physical redundant path 2.

[0079] Here, the optical frequency slot cost and the SRLG cost described in the second embodiment are used in combination, and as shown in the following formula (3), the cost C for each path obtained by summing up the respective costs path can also be used. TIFF0007684248000003.tif27161

[0080] In the example described in the second embodiment, the SRLG cost calculated by the upper layer NMS is equal for the logical redundant path 1 corresponding to the physical redundant path 1 and the logical redundant path 2 corresponding to the physical redundant path 2. By using the optical frequency slot cost in combination here, it becomes possible to select the logical redundant path 2 "C ←→ B ←→ H ←→ G ←→ F ←→ A ←→ E" as the logical redundant path. When there are multiple candidate logical paths with equal costs calculated by formula (3), the redundant system logical path can be selected by further using transmission characteristic information such as OSNR.

[0081] Note that the calculation of SRLG cost and optical frequency slot cost may be performed by the lower-layer NMS, or the upper-layer NMS may obtain physical network information from the lower-layer NMS and perform the calculation. Also, it is possible for the upper-layer NMS and the lower-layer NMS to share the calculation of these costs.

[0082] As described above, the present invention has been described by taking the above-described embodiments as exemplary examples. However, the present invention is not limited to the above-described embodiments. That is, within the scope of the present invention, various aspects understandable by those skilled in the art can be applied.

Description of Reference Numerals

[0083] 1000, 2000 Multi-layer Network System 1100 First Network Management Device 1110 Acquisition Information Storage Unit 1200 Second Network Management Device 1210 Network Information Storage Unit 1300 Optical Node Device

Claims

1. A logical path setting means for setting a logical path in a packet network, and a receiving means for receiving physical network information including path information and signal quality information of an optical network, wherein the logical path setting means sets the logical path corresponding to the physical path in the optical network based on the previously acquired physical network information, extracts a plurality of candidates for the set logical path based on the path information, and determines one logical path from among the plurality of candidates based on the physical network information A network management device.

2. The receiving means receives bandwidth information including unused free slot information in the optical network The network management device according to claim 1.

3. The receiving means receives signal quality information regarding at least one of an optical signal-to-noise ratio and a Q value in the optical network The network management device according to claim 1 or 2.

4. The physical path in the optical network is a physical topology connected in a ring shape, The logical path in the packet network is a logical topology connected in a mesh shape The network management device according to any one of claims 1 to 3.

5. Setting a logical path in a packet network, receiving physical network information including path information and signal quality information of an optical network, wherein setting the logical path sets the logical path corresponding to the physical path in the optical network based on the previously acquired physical network information, extracts a plurality of candidates for the set logical path based on the path information, and includes determining one logical path from among the plurality of candidates based on the physical network information. A path setting method.

6. The path setting method according to claim 5, wherein bandwidth information including unused free slot information in the optical network is received.

7. The path setting method according to claim 5 or 6, wherein signal quality information regarding an optical signal-to-noise ratio or a Q value in the optical network is received.

8. The physical path in the optical network is a physical topology connected in a ring shape, The logical path in the packet network is a logical topology connected in a mesh shape. The path setting method according to any one of claims 5 to 7.

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