JP2014039208A - Network design device, network design method, and network design program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network design device, a network design method, and a network design program capable of designing a complicated network equipped with multiple paths.SOLUTION: A network design device comprises: a counting processing unit for counting the number of paths passing through a link between nodes in a network equipped with a plurality of paths through which optical signals having a plurality of wavelengths are transmitted respectively, for each link; a setting processing unit for setting an upper limit number of transmission systems used for transmitting a wavelength multiplex optical signal for each link, on the basis of the number of paths; and an allocation processing unit for allocating wavelengths of optical signals multiplexed into the wavelength multiplex optical signal to each of the plurality of paths according to a restriction condition that the number of repeatedly usable optical signals having the same wavelength is made to be equal to or smaller than the upper limit number set by the setting processing unit for each link. When the restriction condition prevents allocation of the wavelengths, the allocation processing unit mitigates the restriction condition and allocates the wavelengths.

Description

  The present invention relates to a network design apparatus, a network design method, and a network design program.

  As the demand for communication increases, optical networks using WDM technology (WDM: Wavelength Division Multiplexing) have become widespread. The WDM technique is a technique for multiplexing and transmitting a plurality of optical signals having different wavelengths. According to the WDM technology, for example, it is possible to multiplex an optical signal with a transmission speed of 40 (Gbps) × 40 waves and transmit it as a wavelength multiplexed optical signal of 1.6 (Tbps).

  A wavelength division multiplexing transmission apparatus (hereinafter referred to as a WDM apparatus) to which this WDM technology is applied is provided with an optical transceiver called a transponder or the like for each line, and a plurality of optical signals are transmitted via the plurality of optical transceivers. Are input and output respectively. The WDM device transmits the wavelength multiplexed optical signal obtained by multiplexing the optical signals input from the optical transceiver to other devices, and separates the optical signal of a predetermined wavelength from the wavelength multiplexed optical signals received from the other devices. And output from the optical transceiver.

  In the design of a network composed of WDM devices, the wavelength of an optical signal multiplexed on a wavelength multiplexed optical signal is assigned to each path in the network. Here, the path refers to a series of communication paths connecting the start point node and the end point node in the network.

  Regarding network design, for example, Patent Document 1 discloses a technology for designing a path when there are restrictions on the number of wavelengths that can be used in the entire network or when there are routers capable of wavelength switching in the network. Yes.

Japanese Patent Laid-Open No. 2004-80666

  Since the technology disclosed in Patent Document 1 designs a path based on a constraint that routes do not overlap between the same wavelength and the same node, even if the cost can be reduced, the wavelength is set for the path. It cannot be assigned flexibly. Therefore, it is difficult to apply this technique to a complex network provided with a large number of paths.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a network design apparatus, a network design method, and a network design program capable of designing a complex network provided with a large number of paths. .

  The network design apparatus described in this specification counts the number of paths passing through the link for each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are respectively transmitted. A processing unit; a setting processing unit configured to set an upper limit number of transmission systems used for transmitting wavelength division multiplexed optical signals for each link based on the number of paths counted by the counting processing unit; and the link For each, the wavelength of the optical signal multiplexed into the wavelength-multiplexed optical signal is determined according to a constraint condition that the number of optical signals of the same wavelength that can be used redundantly is equal to or less than the upper limit number set by the setting processing unit. An allocation processing unit that allocates to each of the plurality of paths, and when the allocation processing unit is unable to allocate a wavelength due to the constraint condition, Assign.

  In the network design method described in this specification, for each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, the number of paths passing through the link is counted. Based on the counted number of paths, an upper limit number of transmission systems used for transmitting wavelength multiplexed optical signals is set for each link, and the same wavelength light that can be used redundantly for each link. In accordance with a constraint condition that the number of signals is equal to or less than the upper limit number set by the setting processing unit, the wavelength of the optical signal multiplexed on the wavelength-multiplexed optical signal is allocated to each of the plurality of paths, and the wavelength is allocated In the processing, when a wavelength cannot be assigned due to the constraint condition, the constraint condition is relaxed and a wavelength is allocated.

  The network design program described in this specification counts the number of paths passing through the link for each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are respectively transmitted. Based on the counted number of paths, an upper limit number of transmission systems used for transmitting wavelength multiplexed optical signals is set for each link, and the same wavelength light that can be used redundantly for each link. Assigning the wavelength of the optical signal multiplexed to the wavelength-multiplexed optical signal to each of the plurality of paths according to a constraint condition that the number of signals is equal to or less than the upper limit number set by the setting processing unit. In the process of executing and assigning the wavelength, if the wavelength cannot be assigned due to the restriction condition, the restriction condition is relaxed and the wavelength is assigned.

  The network design device, the network design method, and the network design program described in this specification have an effect that a complex network provided with a large number of paths can be designed.

It is a block diagram which shows an example of the network containing a network design apparatus. It is a figure which shows an example of the network provided with two paths which use the same wavelength. It is a block diagram which shows the function structure of a WDM apparatus. It is a block diagram which shows the structure of the transmission system between WDM apparatuses. It is a figure which shows an example of the some path | pass provided in the network. FIG. 6 is a diagram showing an example of wavelength allocation for the path shown in FIG. 5. It is a figure which shows the other example of the wavelength allocation with respect to the path | pass shown by FIG. It is a block diagram which shows the structure of a network design apparatus. It is a block diagram which shows the structure of the function formed in CPU. 6 is a table showing design information related to the network shown in FIG. 5. It is a table | surface which shows the content of each variable used in a mathematical programming model. It is a figure which shows the example of the network containing a some congestion link. It is a flowchart which shows the flow of a wavelength allocation process. It is a figure which shows the other example of the some path | pass provided in the network. It is a table | surface which shows the transmission system information regarding the network shown by FIG. It is a figure which shows the example of a failure of wavelength allocation with respect to the path | route of the network shown by FIG. It is a table | surface which shows the priority information for every link in the network shown by FIG. FIG. 15 is a diagram showing a successful example of wavelength allocation for the network path shown in FIG. 14. It is a block diagram which shows the structure of the network which is an example of application of a network design apparatus. 20 is a list of congested links in the network shown in FIG. 20 is a list of non-congested links in the network shown in FIG. It is a table | surface which shows the wavelength allocation information obtained by the network design apparatus. It is a figure which shows the number of the transmission systems used for the network shown by FIG.

  FIG. 1 is a configuration diagram illustrating an example of a network including a network design apparatus. The network design device 1 is connected to a plurality of WDM devices 20 via a monitoring and control network NW such as a LAN (Local Area Network). The network design device 1 may have the same function as a network management device such as an NMS (Network Management System).

  The WDM device 20 is an optical add / drop device called, for example, ROADM (Reconfigurable Optical Add-Drop Multiplexer). Each WDM device 20 is connected to each other by an optical fiber, and constitutes, for example, a ring network 2. The network 2 is not limited to the form shown in FIG. 1, and may be, for example, a mesh type.

  Each WDM device 20 receives optical signals of arbitrary wavelengths λin1, λin2, λin3,..., Wavelength-multiplexes the optical signals, and transmits the optical signals to other WDM devices 20 as wavelength-multiplexed optical signals. Each WDM device 20 separates and outputs optical signals of arbitrary wavelengths λout1, λout2, λout3,... From the wavelength multiplexed optical signal transmitted from the other WDM device 20.

  The network design device 1 assigns wavelengths of optical signals input / output to / from each WDM device 20 to a plurality of paths provided in the network 2. As a result, an optical signal having a predetermined wavelength is transmitted between any WDM devices 20. In the following description, the input of the optical signals λin1, λin2, λin3... From the outside to the WDM device 20 will be referred to as “insertion”, and the optical signals λout1, λout2, λout3,. The output of ・ is expressed as “branch”. A signal obtained by multiplexing optical signals of a plurality of wavelengths is referred to as a “wavelength multiplexed optical signal”, and an optical signal of a predetermined wavelength is branched from another WDM device 20 after being inserted into the WDM device 20. A communication path that is transmitted before the transmission is expressed as “path”.

  The total number (upper limit number) of wavelengths that the WDM apparatus 20 can multiplex with wavelength-multiplexed optical signals is finite (for example, 88 waves) depending on the performance of the wavelength selective switch (WSS) used. For this reason, when the number of paths passing through two adjacent WDM devices 20 exceeds the total number of wavelengths that can be multiplexed, it is necessary to add transmission lines between the WDM devices 20, that is, optical fibers and the WDM devices 20 themselves. It is said.

  FIG. 2 shows an example of a network provided with two paths using the same wavelength. In this network, WDM devices (A) to (D) 20 are provided, and the WDM device (A) 20 is connected to other WDM devices (B) to (D) 20 via the optical fiber 3. ing. Here, the WDM device (A) 20 includes a route # 1 connected to the WDM device (C) 20, a route # 2 connected to the WDM device (D) 20, and a WDM device (B) 20. Route # 3 is connected.

  This network is provided with a plurality of paths P1 to Pn passing through the WDM apparatus (C) 20, the WDM apparatus (A) 20, and the WDM apparatus (D) 20, and a plurality of paths P1 to Pn include a plurality of paths P1 to Pn. Λ1 to λn are respectively assigned. Assuming that the wavelengths λ1 to λn are all wavelengths that can be multiplexed with the wavelength multiplexed optical signal, a new path Pi passing through the WDM device (B) 20, the WDM device (A) 20, and the WDM device (D) 20 is set. When provided, the wavelength is insufficient between the WDM device (A) 20 and the WDM device (D) 20.

  For this reason, the WDM apparatus (A) 20 and the WDM apparatus (D) 20 are provided with double transmission paths. That is, the WDM device (A) 20 and the WDM device (D) 20 are connected via two pairs of optical fibers 3. In this example, the wavelength multiplexed optical signal is bidirectionally transmitted by a pair of optical fibers 3 (see arrows in FIG. 3), but unlike this, the wavelength multiplexed optical signal is bidirectionally transmitted by a single optical fiber 3. You may employ | adopt a core bidirectional | two-way system.

  Further, in the WDM apparatus (A) 20 and the WDM apparatus (D) 20, not only the transmission path but also a transmission unit for transmitting the wavelength multiplexed optical signal is made redundant. FIG. 3 is a configuration diagram showing a functional configuration of the WDM apparatus (A) 20.

  The WDM apparatus 20 includes a plurality of transmission units 20a to 20d corresponding to the respective routes # 1 to # 3, a control unit 21, a plurality of DEMUX units 22, a plurality of MUX units 23, and a plurality of transceivers (TPs). 24). Each of the plurality of transmission units 20 a to 20 d includes an amplification unit 201 and a switch unit 202. In FIG. 3, the amplification unit 201 and the switch unit 202 are shown only for the transmission units 20a and 20b, but the other transmission units 20c and 20d have the same configuration. In addition, only a plurality of DEMUX units 22 and a plurality of MUX units 23 connected to the transmission units 20a and 20b are shown, but the DEMUX units are similarly applied to the other transmission units 20c and 20d. 22 and the MUX unit 23 are connected.

  The amplifying unit 201 amplifies the wavelength-multiplexed optical signal output to the paths # 1 and # 2 and the input-side amplifier 201b that amplifies the wavelength-multiplexed optical signals input from the paths # 1 and # 2, respectively. An output side amplifier 201a is included. The switch units 202 each include a wavelength selective switch (WSS) 202a and an optical splitter (SPL) 202b.

  The optical splitter 202b branches the wavelength multiplexed optical signal input to the input port and outputs it from a plurality of output ports. In this example, the optical splitter 21 is used as a branching unit. However, the present invention is not limited to this, and only an optical signal having a predetermined wavelength may be branched using a wavelength selective switch or the like.

  The input port of the optical splitter 202b is connected to the input-side amplifier 201b, while the plurality of output ports are connected to the DEMUX unit 22 and the wavelength selection switch 201a on the other side. The optical splitter 202b outputs the wavelength multiplexed optical signal input from the input-side amplifier 201b to the DEMUX unit 22 and the wavelength selective switch 202a on the other path.

  The wavelength selective switch 202a receives a plurality of optical signals having different wavelengths from a plurality of input ports, multiplexes the optical signal having the selected wavelength with the wavelength multiplexed optical signal, and outputs the multiplexed signal from the output port. The selection of the wavelength is performed for each input port based on the setting from the control unit 21.

  The plurality of input ports of the wavelength selective switch 202a are connected to the MUX unit 23 and the optical splitter 202b on the other side, while the output port is connected to the output side amplifier 201a. The wavelength selective switch 22 multiplexes the optical signal inserted from the MUX unit 23 and the optical signal of the selected wavelength, and outputs the multiplexed signal to the corresponding path via the output-side amplifier 201a.

  In order to branch the optical signal, the DEMUX unit 22 is connected to the output port 9 of the splitter 202b, separates the wavelength multiplexed optical signal input from a predetermined path, and outputs the optical signal to each wavelength. . The DEMUX unit 22 is connected to a plurality of transceivers 24 and has a tunable filter corresponding to each transceiver 24. The DEMUX unit 22 separates the optical signal having the wavelength selected by the tunable filter from the wavelength multiplexed optical signal input from the splitter 202 b and outputs the optical signal to the transceiver 24.

  Selection of the wavelength in the tunable filter is performed for each transmitter / receiver 24 according to the setting from the control unit 21. The optical signal output to the transceiver 24 is output to an external device. Note that the tunable filter may be provided in a reception processing unit in the transceiver 24.

  The MUX unit 22 is connected to a plurality of transceivers 24 to insert an optical signal, and outputs an optical signal input from an external device via the transceiver 24 to an input port of the wavelength selective switch 202a. The MUX unit 22 includes an arrayed waveguide grating and the like, bundles optical signals from a plurality of transceivers 24, and outputs them to the wavelength selective switch 202a.

  The control unit 21 is an arithmetic processing circuit such as a CPU (Central Processing Unit), for example, and controls the WDM apparatus 20 based on a predetermined program. In addition, the control part 21 is not limited to what functions by software in this way, You may function by hardware, such as an application specific integrated circuit.

  The control unit 21 communicates with the network design device 1 via the monitoring control network NW, and acquires wavelength assignment information indicating wavelengths to be assigned for each path. The control unit 21 sets the wavelength to be selected for the wavelength selective switch 202a based on the wavelength assignment information.

  In the WDM apparatus (A) 20, single transmission units 20a and 20d are provided for the routes # 1 and # 3, respectively, while two transmission units 20b and 20c are provided for the route # 2. It has been. On the other hand, as shown in FIG. 4, the WDM apparatus (D) 20 is also provided with two transmission units 20e and 20f for the same route # 2. The two transmission units 20b and 20c of the WDM apparatus (A) 20 are connected to the two transmission units 20e and 20f of the WDM apparatus (D) 20 through a pair of optical fibers 3, respectively.

  According to this configuration, since two different wavelength multiplexed optical signals can be transmitted between the WDM apparatus (A) 20 and the WDM apparatus (D) 20, as shown in FIG. Two different paths P1 and Pi to be used can be set. In this way, a pair of transmission units (20b, 20e), (20c, 20f) used for transmitting wavelength-multiplexed optical signals between two adjacent WDM devices (A), (D) 20 are provided. In the following description, it is expressed as “transmission system” (see reference numeral 30).

  Next, wavelength allocation performed by the network design apparatus 1 according to the present embodiment will be described. FIG. 5 shows an example of a plurality of paths provided in the network. In this network, nodes (A) to (J) are connected in series in this order. The “node” refers to a communication device such as a WDM apparatus 20 installed in a station building or the like.

  The network is provided with a plurality of paths P1 to P9. Each of the paths P1 to P9 passes through a node and a link within a range indicated by arrows at both ends. For example, the path P1 passes through the nodes (A) to (D) and the links between the nodes (A) to (D). Further, the path P2 passes through the nodes (E) to (G) and the links between the nodes (E) to (G). A “link” refers to a virtual line connecting two adjacent nodes in the network.

  According to this path setting, for example, the optical signal inserted into the WDM apparatus 20 of the node (A) by the path P1 is branched from the WDM apparatus 20 of the node (D), and conversely, the WDM apparatus 20 of the node (D). The optical signal inserted into is branched from the WDM device 20 of the node (A). Further, the optical signal inserted into the WDM device 20 at the node (E) by the path P2 is branched from the WDM device 20 at the node (G), and conversely, the optical signal inserted into the WDM device 20 at the node (G). The signal is branched from the WDM device 20 of the node (E). Similarly, other optical signals are inserted and branched for the other paths P3 to P9.

  FIG. 6 shows an example of wavelength allocation for the paths P1 to P9 shown in FIG. Here, it is assumed that the total number of wavelengths that the WDM apparatus 20 can multiplex with the wavelength multiplexed optical signal is four, and that the wavelengths λ1 to λ4 can be used in one transmission system. A frame drawn with a dotted line indicates the wavelengths λ1 to λ4 used in the transmission systems (1) and (2). For example, the wavelength P2 of one transmission system (1) is assigned to the path P1.

  In this example, paths P2 and P9 are assigned the same wavelength λ1 redundantly in the link between nodes (E) and (F). The paths P3 and P8 are assigned the same wavelength λ2 redundantly in each link between the nodes (E) to (H). For this reason, according to the wavelength allocation of this example, it is necessary to provide two transmission systems (1) and (2) in the transmission section from the nodes (E) to (H).

  FIG. 7 shows another example of wavelength assignment for the path shown in FIG. In this example, unlike the example of FIG. 6, the wavelength λ1 of the transmission system (1) is assigned to the path P7. The path P8 is assigned the wavelength λ4 of the transmission system (2) between the nodes (E) and (F), and the wavelength λ4 of the transmission system (1) between the nodes (F) to (H). Is assigned. Here, the optical signal of the path P8 is transmitted between one transmission system (2) and the other transmission system (1) according to the setting of the wavelength selective switch 202a provided in the WDM device 20 of the node (F). Means are switched.

  According to the wavelength assignment of this example, since two transmission systems (1) and (2) are provided only between the nodes (E) and (F), the equipment cost is reduced when compared with the example of FIG. The The efficient wavelength allocation as shown in FIG. 7 is performed by the network design apparatus 1 using a method such as mathematical programming to construct an appropriate model of the network, and to obtain an optimal solution (wavelength allocated for each path). Realized by guiding.

  FIG. 8 shows the configuration of the network design apparatus 1. The network design device 1 is a computer device such as a server, for example. The network design apparatus 1 includes a CPU 10, a ROM (Read Only Memory) 11, a RAM (Random Access Memory) 12, an HDD (Hard Disk Drive) 13, a communication processing unit 14, a portable storage medium drive 15, an input processing unit 16, And an image processing unit 17 and the like.

  The CPU 10 is arithmetic processing means, and performs wavelength allocation processing for paths according to a network design program. The CPU 10 is communicably connected to the units 11 to 17 via the bus 18. The network design apparatus 1 is not limited to one that operates by software, and hardware such as an application specific integrated circuit may be used instead of the CPU 10.

  The RAM 12 is used as a working memory for the CPU 10. The ROM 11 and the HDD 13 are used as storage means for storing a program for operating the network design apparatus 1. The communication processing unit 14 is a communication unit such as a network card that communicates with an external device via a network such as a LAN. Taking the configuration shown in FIG. 1 as an example, the communication processing unit 14 processes communication with a plurality of WDM apparatuses 20 via the monitoring control network NW.

  The portable storage medium drive 15 is a device that writes information to and reads information from the portable storage medium 150. Examples of the portable storage medium 150 include a USB memory (USB: Universal Serial Bus), a CD-R, and a memory card.

The network design apparatus 1 further includes an input device 160 for performing an information input operation and a display 170 for displaying an image. The input device 160 is input means such as a keyboard and a mouse, and input information is output to the CPU 10 via the input processing unit 16. The display 170 is a display unit that displays an image such as a liquid crystal display. The displayed image data is output from the CPU 10 to the display via the image processing unit 17. Instead of the input device 160 and the display 170, a device such as a touch panel having these functions can be used.

  The CPU 10 executes a program stored in the ROM 11 or the HDD 13 or a program read from the portable storage medium 150 by the portable storage medium drive 15. This program includes not only the OS (Operating System) but also the network design program described above. The program may be downloaded via the communication processing unit 14.

  When the CPU 10 executes the network design program, a plurality of functions are formed. FIG. 9 shows a configuration of functions formed in the CPU 10. The CPU 10 includes a counting processing unit 100, a setting processing unit 101, a generation processing unit 102, an allocation processing unit 103, and a transmission processing unit 104. 9 shows not only the function units 100 to 104 of the CPU 10, but also various types of information 130 to 134 stored in the HDD 13 in relation to the functions. Note that the storage means for the information 130 to 134 is not limited to the HDD 13, and may be the ROM 11 or the portable storage medium 150.

  The count processing unit 100 counts the number of paths passing through the links for each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted. The count processing unit 100 reads the topology information 130 and the path information 131 related to the network to be designed from the HDD 13 and performs a counting process using these pieces of information.

  The topology information 130 is information indicating a network configuration, that is, a connection relationship between nodes via a link. For example, the topology information 130 is configured by associating identifiers of links in the network with identifiers of a pair of nodes connected via the links. The network design device 1 may generate the topology information 130 and the path information 131 by the own device 1, or obtain it from the outside via the monitoring control network NW, the portable storage medium 150, or the input device 160, for example. May be.

  On the other hand, the path information 131 is information indicating a route for each path set in the network. The path information 131 includes, for example, node identifiers corresponding to the start point and end point of the path, and one or more link identifiers that pass from the start point to the end point.

  Taking the path of FIG. 5 as an example, for example, the counting processing unit 100 sets the number of links between nodes (A) and (B) to 1, and the number of links between nodes (B) and (C). 2. Count the number of paths of the link between nodes (E) and (F) as 6. From this counting process, the degree of path congestion (degree of concentration) is ascertained for each link in the network.

  Based on the number of paths counted by the counting processing unit 100, the setting processing unit 101 determines the upper limit number of transmission systems (see reference numeral 30 in FIG. 4) used for transmitting the wavelength multiplexed optical signal for each link. Set. For example, the setting processing unit 101 may determine the upper limit number of transmission systems based on a value obtained by dividing the number of paths for each link by the total number of wavelengths that can be multiplexed into the wavelength multiplexed optical signal. In this case, the upper limit number of the transmission system is obtained as an integer by rounding up the value after the decimal point of the quotient obtained by division.

  In the example of FIG. 5, the total number of wavelengths that the WDM apparatus 20 can multiplex with the wavelength multiplexed optical signal is four waves. Therefore, the upper limit number of the transmission system becomes 1, for example, by calculating 1 ÷ 4 for the link between the nodes (A) and (B). Further, the link between the nodes (B) and (C) is 2 by calculating 2 ÷ 4, and the link between the nodes (E) and (F) is 2 by calculating 6 ÷ 4. It becomes.

  Further, the upper limit number of transmission systems may be determined in anticipation of an increase in future paths in the network. In this case, the setting processing unit 101 corrects the upper limit number of transmission systems in accordance with an external operation. For example, when 6 is input as the expected number of path increases in the link between the nodes (A) and (B) via the input device 160, the setting processing unit 101 sets the upper limit number of transmission systems of the link. Correct from 1 to 2. As a result, it is possible to design a network that anticipates future increases in paths.

  By setting the upper limit number of transmission systems in this way, network design is performed so that the transmission system is reduced. The setting processing unit 101 writes the upper limit number of transmission systems in the HDD 13 as transmission system information 132 together with the number of paths obtained from the counting processing unit 100.

  FIG. 10 shows design information related to the network shown in FIG. In FIG. 10, “the number of paths” and “the maximum number of transmission systems” indicate the transmission system information 132. “Number of paths” indicates the number of paths for each link counted by the counting processing unit 100, and “Transmission system upper limit number” indicates the upper limit number of transmission systems set by the setting processing unit 101. Other information will be described later.

  The allocation processing unit 103 multiplexes the number of optical signals of the same wavelength that can be used redundantly for each link into the wavelength multiplexed optical signal in accordance with a restriction condition that is less than or equal to the upper limit number of transmission systems set by the setting processing unit. The wavelength of the optical signal to be processed is assigned to each of the plurality of paths. Therefore, the allocation processing unit 103 allocates wavelengths so that optical signals having the same wavelength can be used in the same link, and the total number of transmission systems in the network is minimized.

  The allocation processing unit 103 allocates wavelengths based on the topology information 130, path information 131, and transmission system information 132 in the HDD 13. More specifically, the allocation processing unit 103 constructs a mathematical programming model using these pieces of information as variables, and obtains an optimal solution under a predetermined constraint condition.

  Hereinafter, a mathematical programming model used in the wavelength assignment process will be described. The allocation processing unit 103 uses, for example, the following expression (1) as the objective function. FIG. 11 shows the contents of variables used in the following equations.

  According to Expression (1), the allocation processing unit 103 allocates wavelengths so that the sum of the wavelength label numbers used for each path is minimized. Here, the label number is information corresponding to a name given for each wavelength. The allocation processing unit 103 selects a wavelength to be allocated with priority from the smallest label number.

  Further, the allocation processing unit 103 uses, for example, the following expressions (2) and (3) as the constraint conditions.

  According to Equation (2), the allocation processing unit 103 allocates wavelengths according to the constraint that a single wavelength is allocated to each path. This restriction condition is based on a technical restriction that the wavelength of the optical signal cannot be switched to another wavelength during the path.

  On the other hand, according to Expression (3), the assignment processing unit 103 assigns wavelengths in accordance with the constraint that the number of identical wavelengths that can be used redundantly in the same link is less than or equal to the upper limit number of transmission systems. This constraint condition is that a plurality of wavelengths that can be multiplexed on one wavelength-multiplexed optical signal are different from each other, so that one transmission system (see FIG. 4) can transmit only one set of the plurality of wavelengths. based on. For example, in the example of FIG. 5, since the upper limit number of transmission systems in the link between the nodes (E) and (F) is 2 (see FIG. 10), it is possible to use up to two of each wavelength. Since the upper limit number of other links is 1, each wavelength can be used only one by one.

  By constructing the mathematical programming model as described above to obtain an optimal solution, the allocation processing unit 103, as illustrated in FIG. 7, results in the minimum number of transmission systems being used. Efficient wavelength allocation is performed. Here, the objective function in the mathematical programming model is not limited to the above equation (1), and for example, the following equation (4) may be used. Here, the variable Sys (s) represents the number of transmission systems actually used in each link s.

  According to Expression (4), the allocation processing unit 103 allocates wavelengths so that not only the total number of wavelength label numbers used for each path but also the number of transmission systems used is minimized. Note that the allocation processing unit 103 uses, for example, the following formula (5) in addition to the above formulas (2) and (3) as a constraint condition. Equation (5) is used to derive the number of transmission systems used. Note that the assignment processing unit 103 is not limited to mathematical programming, and may perform wavelength assignment using another analysis method.

  If the wavelength cannot be allocated due to the constraint condition, the allocation processing unit 103 relaxes the constraint condition and allocates the wavelength. More specifically, when the wavelength cannot be allocated due to the constraint condition, the allocation processing unit 103 sets the upper limit value of the transmission system corresponding to the link selected based on the priority information 133 indicating the priority of each link. Increase. A specific example in the case where the wavelength cannot be assigned due to the constraint condition, that is, the optimum solution of the mathematical programming model cannot be obtained will be described later.

  As illustrated in FIG. 9, the priority information 133 is generated by the generation processing unit 102 in accordance with an instruction from the allocation processing unit 103. Hereinafter, a method for generating the priority information 133 will be described with reference to FIG.

  The generation processing unit 102 selects a link through which a predetermined number of paths or more pass in the network as a congestion link, and selects other links as non-congested links. For example, in the example of FIG. 5, when a link through which five or more paths pass is a congestion link, the link between the nodes (E) and (F) corresponds to the congestion link (see “congestion link”), and other The link is a non-congested link (see “Non-congested link”).

  The generation processing unit 102 calculates the ratio of the number of paths passing through the link to the total number of wavelengths that can be multiplexed in the wavelength multiplexed optical signal, and the ratio (hereinafter referred to as “usage rate”) is equal to or greater than the threshold. As the high utilization link. The high utilization group is selected from non-congested links. For example, when the threshold is 70 (%), the link between the nodes (F) and (G) has four paths, and the usage rate with respect to the total number of wavelengths that can be multiplexed (four waves) is 100 ( %), It corresponds to the high utilization link. That is, in this example, a link having a path number of 3 or more corresponds to a high usage rate link (see “high usage rate link”).

  Further, the generation processing unit 102 calculates, for each link excluding the congested link, that is, for each non-congested link, the number of paths that pass through the congested link among the paths that pass through the non-congested link as a congestion-related index value. This congestion related index value indicates the number of paths related to the congestion link for each non-congested link. For example, since the link between the nodes (F) and (G) passes through the three paths P2, P3, and P8 via the congestion link (link between the nodes (E) and (F)), the congestion related The index value is 3. Further, since the link between the nodes (D) and (E) is via two paths P4 and P6 that pass through the congestion link, the congestion-related index value is 2 (see “Congestion-related index area”). .

  The generation processing unit 102 generates priority information for each link based on the above-described usage rate (that is, whether it corresponds to a high usage rate link) and the congestion related index value. In this example, the generation processing unit 102 gives a higher priority to the link corresponding to the high usage link than the other links. Furthermore, the generation processing unit 102 gives a higher priority to a link having a higher congestion related index value. That is, when determining the priority, the generation processing unit 102 preferentially determines the condition as to whether or not it corresponds to the high usage rate link, and determines the congestion related index value at the next stage.

  The priority information 133 generated according to this method is shown as “priority” in FIG. As for the priority, “1” is the highest and “8” is the lowest. Note that, when the congestion-related index values of the links corresponding to the high usage link or the links not corresponding to the high usage link are the same, the priority of any link may be increased.

  The allocation processing unit 103 increases the upper limit value of the transmission system corresponding to the link selected based on the priority information 133 when the wavelength cannot be allocated due to the constraint condition. In the example illustrated in FIG. 10, when the allocation processing unit 103 cannot allocate a wavelength, first, the upper limit of the transmission system corresponding to the link between the nodes (F) and (G) whose priority is “1”. Increase the value.

  When the wavelength cannot be assigned due to the increase in the upper limit value, the allocation processing unit 103 further increases the upper limit value corresponding to the link between the nodes (G) and (H) having the priority “2”. . In this way, the allocation processing unit 103 sequentially increases the upper limit value of the transmission system corresponding to each non-congested link in order of priority until the wavelength allocation is successful, and corresponds to the above formula (3). The constraint condition to be repeatedly relaxed.

  As a result, the allocation processing unit 103 can reliably perform optimal wavelength allocation. The priority information 133 may be formed as a priority list in which the links are arranged in order of priority. In this example, the generation processing unit 102 generates the priority information 133 based on the usage rate and the congestion-related index value. However, the priority information 133 is generated based on either one of the priority information 133. Also good.

  Further, in this example, a network including a single congested link is described, but there are also networks including a plurality of congested links. A method for generating priority information 133 in the case of a network including a plurality of congested links will be described below. FIG. 12 shows an example of a network including a plurality of congested links.

  The nodes (A) to (L) are connected via links so as to form a mesh network. The plurality of paths P1 to P18 are provided between nodes indicated by arrows at both ends. A circle represented by a one-dot chain line surrounds paths P1 to P18 that pass through the link in common for each link.

  In this example, if links that pass through six or more paths P1 to P18 are congested links, a link between nodes (D) and (E), a link between nodes (E) and (F), and a node (H ) And (I) are three congested links (see thick lines). The generation processing unit 102 determines, for each of the paths P1 to P18, a weighting degree corresponding to the number of congested links through which the path passes, and generates priority information 133 based on the weighting degree of the path passing through the congested link. To do.

  For example, since the path P2 passes through two congested links, the weight frequency is set to 2. Since each of the paths P8, P9, and P14 passes through one congested link, the weight frequency is set to 1.

  Next, as an example, the congestion related index value of the link between the nodes (E) and (H) corresponding to the non-congested link is calculated. The paths that pass through the link are paths P2, P8, P9, and P14. Therefore, the congestion related index value of the link is determined to be 5 by calculating the sum (2 + 1 + 1 + 1) of the respective weight frequencies of the four paths P2, P8, P9, and P14. As described above, by generating the priority information 133 based on the weighting frequency corresponding to the number of congested links through which the path passes, the priority information 133 can be appropriately generated even for a network including a plurality of congested links. Is possible.

  As illustrated in FIG. 9, the assignment processing unit 103 writes the wavelength assignment result in the HDD 13 as the wavelength assignment information 134. The wavelength assignment information 134 indicates the correspondence between the identifiers of the respective wavelengths and the assigned path identifiers. Note that the content of the wavelength assignment information 134 may be displayed on the display 170 so that the operator can recognize it.

  Also, the transmission processing unit 104 reads the wavelength assignment information 134 from the HDD 13 and transmits it to the WDM apparatus 20 via the monitoring control network NW. The wavelength allocation information 134 is output from the communication processing unit 14 to the monitoring control network NW. Then, when receiving the wavelength assignment information 134, the control unit 21 of the WDM apparatus 20 performs setting processing for each wavelength selective switch 202a based on the wavelength assignment information 134. The transmission of the wavelength assignment information 134 is executed based on an instruction operation by the input device 160, for example.

  As described above, since the network design apparatus 1 transmits the wavelength allocation information 134 to the WDM apparatus 20, after the network design is completed, the wavelength allocation setting for the path can be performed quickly. The transmission processing of the wavelength assignment information 134 is not limited to this, and may be performed by another device such as a network management device.

  Next, the flow of wavelength assignment processing of the network design apparatus 1 will be described with reference to FIG. The wavelength assignment process is started in response to an operation from the input device 160, for example. When the wavelength assignment process is started, the count processing unit 100 acquires the topology information 130 and the path information 131 from the HDD 13 (step St1).

  Next, the count processing unit 100 passes the link for each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are respectively transmitted based on the topology information 130 and the path information 131. The number of paths to be counted is counted (step St2). Next, the setting processing unit 101 sets the upper limit number of transmission systems used for transmitting the wavelength multiplexed optical signal for each link based on the number of paths counted by the counting processing unit 100 (step St3). ).

  Next, the allocation processing unit 103 performs wavelength multiplexing according to a constraint condition that the number of optical signals with the same wavelength that can be used redundantly is less than or equal to the upper limit number of transmission systems set by the setting processing unit 101 for each link. The wavelength of the optical signal multiplexed with the optical signal is assigned to each of the plurality of paths (step St4). At this time, the allocation processing unit 103 performs wavelength allocation by constructing the mathematical programming model described above and obtaining an optimal solution.

  Next, the allocation processing unit 103 determines whether the allocation is successful (step St5). If the allocation is successful (YES in step St5), the allocation processing unit 103 ends the process. On the other hand, if the allocation has failed (YES in step St5), the allocation processing unit 103 determines whether or not the failure is the first failure after the currently executed wavelength allocation process is started (step St6). ).

  If it is the first failure (YES in step St6), the generation processing unit 102 generates priority information 133 (step St7). As described above, the generation processing unit 102 generates the priority information 133 when the wavelength cannot be assigned due to the constraint condition. That is, the priority information 133 is generated for the first time after wavelength allocation fails.

  Therefore, the network design device 1 can save the time required to generate the priority information 133 when the wavelength allocation is successful without failing. The priority information 133 is not limited to this, and may be generated before the assignment processing unit 103 assigns a wavelength (step 4), for example. The determination of whether or not it is the first failure may be performed, for example, by preparing a variable that is added every time the failure occurs and referring to the value of this variable.

  On the other hand, if it is not the first failure (NO in step St6), the allocation processing unit 103 increases the upper limit value of the transmission system corresponding to the link selected based on the priority information 133 (step St8). In other words, the selection of the link to be increased in the upper limit value follows the order of “priority” described above.

  In the case of the example of FIG. 10, when the failure first occurs, the link between the nodes (F) and (G) having the priority “1” is selected, and when the second failure occurs, the priority is “2”. A link between a certain node (G) and (H) is selected. Thereby, the non-congested link is relaxed in the restriction condition expressed by the above formula (3) in descending order of the degree of association with the congested link. This process is performed similarly after the process of step St7.

  Next, the allocation processing unit 103 executes the process of step St4 again. In other words, if the wavelength cannot be allocated due to the constraint condition, the allocation processing unit 103 attempts wavelength allocation by relaxing the constraint condition until the allocation is successful. According to this network design method, the constraint conditions regarding each link are sequentially relaxed in the order of priority, so that wavelength allocation can be performed efficiently without increasing the number of transmission systems.

  With respect to the processing of step St5 described above, a success example and a failure example of the wavelength assignment processing will be described. FIG. 14 shows an example of a plurality of paths P1 to P7 provided in the network. As in the examples described so far, the plurality of paths P1 to P7 are respectively indicated by double arrows. For example, the path P1 is provided so as to pass through the node (A), the node (B), and the node (C) in this order.

  In this network, the node (B) is connected to the node (A), the node (C), and the node (D), and the node (D) is connected to the node (C). In this example, the total number of wavelengths that can be multiplexed by the WDM apparatus 20 is four, and a link through which a path of five or more waves passes is a congested link.

  FIG. 15 shows transmission system information 132 related to the network. Since the link between the nodes (A) and (B) (see “AB”) passes through the five paths P1 to P5, the upper limit number of the transmission system is set to 2, and the upper limit number of the other links is 1 is set.

  FIG. 16 shows the result of assigning wavelengths λ1 to λ4 to the paths P1 to P7, with the upper limit number of the transmission system shown in FIG. 15 as the constraint condition (the above formula (3)). In FIG. 16, the numbers surrounded by circles indicate the upper limit value of the transmission system set for each link. In addition, the wavelengths λ1 to λ4 assigned to the paths P1 to P7 are shown in parentheses accompanying the display of the paths P1 to P7.

  In this example, since there are not enough usable wavelengths in the link between the nodes (B) and (C), it is not possible to assign wavelengths to the two paths P6 and P7 (see “NG” mark). That is, since the upper limit value of the transmission system is 1 (see FIG. 15), only one set of wavelengths λ1 to λ4 can be used for the link, and the two paths P6 and P7 are the same as the other paths P1 and P2. The wavelengths λ1 and λ2 cannot be assigned.

  Further, even if the wavelengths λ3 and λ4 that are not used in the link are assigned to these paths P6 and P7, the wavelengths λ3 and λ4 are transmitted to the other paths P3 and P3 in the link between the nodes (B) and (D). Assigned to P4. Since the upper limit value of the transmission system is 1 for this link (see FIG. 15), the same wavelengths λ1 and λ2 as the other paths P3 and P4 cannot be assigned to the paths P6 and P7. Thus, since the wavelength allocation in this example has failed due to the constraint upper limit, the generation processing unit 102 generates the priority information 133.

  In FIG. 17, in addition to the transmission system information 132, priority information 133 regarding the network of this example is shown. When a link through which five or more paths pass is a congested link, the link between nodes (A) and (B) (see “AB”) is a congested link, and the other links are non-congested links. Applicable. Further, in the case of a high usage rate link, when the usage rate that is the criterion is 70 (%), the usage rate is 100 (%) (number of paths 4 / total number of usable wavelengths 4) (B) And a link between (C) and a link between nodes (A) and (D).

  The congestion related index value is determined based on the number of paths passing through the congestion link (A-B). For example, the link between the nodes (A) and (D) passes through the two paths P1 and P2 among the paths P1 to P5 that pass through the congestion link, so the congestion-related index value is 2.

  The priority is determined according to the method described with reference to FIG. As a result, since the priority of the link between the nodes (A) and (C) is the highest, the allocation processing unit 103 increases the upper limit value of the transmission system corresponding to the link from 1 to 2 (“1 → 2”). "reference). Then, the allocation processing unit 103 allocates wavelengths again according to the constraint condition based on the new upper limit value. The number to be increased at a time is not limited to 1 and may be 2 or more.

  FIG. 18 shows the result of wavelength allocation again. As described above, since the upper limit value of the transmission system corresponding to the link between the nodes (A) and (C) has increased to 2, there are two sets of a plurality of wavelengths λ1 to λ4 that can be used in the link. As a result, the same wavelengths λ1 and λ2 as the other paths P1 and P2 can be assigned to the paths P6 and P7, respectively. As described above, the allocation of the wavelength in this example has succeeded the second time by relaxing the upper limit of restriction.

  In this example, the priority “1” is given to the link between the nodes (A) and (C). Instead, the link between the nodes (B) and (D) having the same congestion-related index value is used. You may give priority "1" to a link. In this case, since the number of transmission systems of the link is 2, the wavelength assignment is still successful by assigning the wavelengths λ3 and λ4 to the paths P6 and P7, respectively.

  Up to now, a small-scale network has been mentioned as an application example of the network design apparatus 1, but the network design apparatus 1 can also be applied to a large-scale network as shown in FIG. This network has 40 nodes N1 to N40 connected via links, and 574 paths (not shown) are provided. In this example, the total number of wavelengths that the WDM apparatus 20 can multiplex with the wavelength multiplexed optical signal is 88 waves. Hereinafter, the inventors will explain the design results obtained by using the above-described network design method for this example.

  FIG. 20 shows a list of congested links in the network shown in FIG. Regarding the “link” column, for example, “N3_N4” represents the link between the nodes N3 and N4, and the “number of paths” column represents the number of paths that pass through the corresponding congested link. These columns are the same in the following description. Here, a link having more than 88 paths is selected as a congested link, and the upper limit number of transmission systems for each congested link is 2.

  FIG. 21 shows a list of non-congested links in the network shown in FIG. The “weight frequency” column indicates the number of paths corresponding to each of the weight frequencies 1 to 4 described with reference to FIG. For example, for the link N2_N3, there are 13 paths with a weight degree of 1, 2 paths with a weight degree of 2, 7 paths with a weight degree of 3, 19 paths with a weight degree of 4, and 5 paths with a weight degree of 5 , There are 35 paths with a weight frequency of 6.

  The “congestion related index value” column indicates the congestion related index value determined based on the weight frequency. For example, the congestion related index value of the link N2_N3 becomes 349 by calculating 1 × 13 + 2 × 2 + 3 × 7 + 4 × 19 + 5 × 5 + 6 × 35.

  Moreover, the code | symbol G has shown the link applicable to a high utilization rate link. In this example, the above ratio is set to 90 (%) as a standard corresponding to the high usage rate link. Each link is arranged in the order of priority from the top of the table.

  About this example, the mathematical calculation model based on said Formula (1)-(3) was constructed | assembled, As a result of trying wavelength allocation, it failed in the 1st-5th time and succeeded in the 6th time. With each failure, the upper limit number of transmission systems of links N2_N3, N10_N2, N35_N24, N21_N11, and N26_33 increased sequentially in order of priority. For this reason, the upper limit number of the transmission systems of the links N2_N3, N10_N2, N35_N24, N21_N11, and N26_33 as well as the congested link is also 2 due to the relaxation of the constraint condition five times.

  FIG. 22 shows the wavelength assignment information 134 obtained by the network design device 1. The “path” column indicates a path identifier, and the “link” column indicates a label number of an assigned wavelength for each link through which the corresponding path passes. Each path is assigned a single wavelength in accordance with the constraint of equation (2) above. For example, the wavelength assigned to the path (2) is only the wavelength of the label number “38”. Note that “-” in the “link” column indicates that the corresponding path does not pass through the link.

  Further, the same wavelength is assigned to different paths according to the constraint condition of the above equation (3). For example, the path (0) and the path (100) are both assigned the wavelength of the label number “32”, and the path (1) and the path (20) are both assigned the wavelength of the label number “37”. (Refer to the dashed-dotted frame).

  FIG. 23 shows the number of transmission systems used in the network shown in FIG. In FIG. 23, “M” circled indicates a congested link (see FIG. 20), and two transmission systems are used for the congested link. A circled “2” indicates a non-congested link in which two transmission systems are used.

  According to the network design of this example, a result that two transmission systems are required in 11 links out of 48 links was obtained. The required design time was about 5 minutes. Note that the time required for one wavelength assignment was approximately 1 minute.

  On the other hand, as a result of constructing a mathematical calculation model based on the above equations (2) to (5) and performing wavelength assignment, a result that two transmission systems are required in 19 links out of 48 links is obtained. It was. Moreover, the time required for the design was about 1 hour. Therefore, according to the mathematical calculation model based on the equations (1) to (3), the number of transmission systems is reduced by 30 (%) or more compared to the mathematical calculation model based on the equations (2) to (5). A suitable design result that the design time was shortened by 80% or more was obtained. This is because the model size of the former mathematical calculation model is smaller than that of the latter.

  For comparison with the mathematical calculation method described above, as a result of wavelength assignment using the heuristic method, the result that two transmission systems are required in 40 links out of 48 links is obtained. It was. In this example, paths are selected and assigned wavelengths in the order of few links, and the number of transmission systems is increased when wavelengths are insufficient. According to this method, since the design result depends on the path selection order, it is theoretically difficult to obtain an optimal solution.

  As described above, the network design device 1 according to the embodiment transmits the wavelength multiplexed optical signal for each link based on the number of paths counted for each link in the network in which a plurality of paths are provided. Set the upper limit of the number of transmission systems to be used. For this reason, the upper limit number of transmission systems is accurately set for each link.

  In addition, the network design device 1 is configured so that the number of optical signals with the same wavelength that can be used redundantly for each link is equal to or less than the upper limit number of the transmission system. A wavelength is assigned to each of the plurality of paths. For this reason, optical signals of the same wavelength are assigned to different paths according to the upper limit number of transmission systems for each link.

  Furthermore, when the wavelength cannot be assigned due to the above-described restriction condition, the network design device 1 relaxes the restriction condition and assigns the wavelength. For this reason, even when the number of wavelengths to be allocated is insufficient, wavelength allocation is reliably performed by repeatedly trying wavelength allocation.

  Therefore, according to the network design apparatus 1, an effect that a complex network having a large number of paths can be designed is obtained. Note that the network design method and the network design program described above also have the same configuration as the network design apparatus 1, and therefore have the same effects.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

In addition, the following additional notes are disclosed regarding the above description.
(Supplementary note 1) For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, a counting processing unit that counts the number of paths that pass through the link;
Based on the number of paths counted by the counting processing unit, a setting processing unit that sets an upper limit number of transmission systems used for transmitting wavelength division multiplexed optical signals for each link;
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal An allocation processing unit for assigning a wavelength to each of the plurality of paths,
The network design apparatus characterized in that the allocation processing unit relaxes the constraint condition and allocates a wavelength when the wavelength cannot be allocated due to the constraint condition.
(Additional remark 2) It further has the production | generation process part which produces | generates the priority information which shows each priority of the said link,
The allocation processing unit relaxes the constraint condition by increasing the upper limit value corresponding to the link selected based on the priority information when a wavelength cannot be allocated due to the constraint condition. The network design device according to supplementary note 1, which is characterized.
(Additional remark 3) The said generation process part produces | generates the said priority information based on the ratio of the number of the said path | routes via the said link with respect to the total number of the wavelengths which can be multiplexed with the said wavelength multiplexing optical signal, It is characterized by the above-mentioned. The network design device according to attachment 2.
(Supplementary Note 4) The generation processing unit selects, as a congested link, the link through which a predetermined number or more of the paths pass in the network, and for each link excluding the congested link, out of the paths through the link The network design device according to appendix 2 or 3, wherein the priority information is generated based on the number of the paths passing through the congested link.
(Supplementary Note 5) When the network has a plurality of the congestion links, the generation processing unit determines, for each path, a weighting degree according to the number of the congestion links that the path passes, and determines the congestion links. The network design device according to appendix 4, wherein the priority information is generated based on the weight frequency of a path that passes through.
(Supplementary note 6) The network design device according to any one of supplementary notes 2 to 5, wherein the generation processing unit generates the priority information when a wavelength cannot be assigned due to the constraint condition.
(Additional remark 7) The said setting process part is based on the value obtained by dividing the number of the paths counted by the said count process part by the number of wavelengths which can be multiplexed with the said wavelength multiplexing optical signal by the said transmission system. The network design device according to any one of appendices 1 to 6, wherein an upper limit number is set.
(Supplementary note 8) The network design device according to any one of supplementary notes 1 to 7, wherein the setting processing unit corrects the upper limit number in accordance with an external operation.
(Supplementary note 9) For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, the number of paths passing through the link is counted,
Based on the counted number of paths, for each link, set an upper limit number of transmission systems used to transmit wavelength multiplexed optical signals,
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal Assign a wavelength to each of the plurality of paths;
In the process of assigning the wavelength, when a wavelength cannot be assigned due to the constraint condition, the network design method is characterized in that the wavelength is assigned by relaxing the constraint condition.
(Supplementary Note 10) When a wavelength cannot be assigned due to the constraint condition, the constraint value is increased by increasing the upper limit value corresponding to the link selected based on priority information indicating the priority of each link. The network design method according to appendix 9, wherein the condition is relaxed.
(Additional remark 11) The said priority information is produced | generated based on the ratio of the number of the said path | routes via the said link with respect to the total number of the wavelengths which can be multiplexed with the said wavelength multiplexing optical signal. Network design method.
(Additional remark 12) The priority information selects the link through which a predetermined number or more of the paths pass in the network as a congested link, and for each link excluding the congested link, out of the paths through the link The network design method according to appendix 10 or 11, wherein the network design method is generated based on the number of the paths passing through the congestion link.
(Supplementary Note 13) When the network has a plurality of the congested links, the priority information determines, for each path, a weight degree corresponding to the number of the congested links through which the path passes, 13. The network design method according to appendix 12, wherein the network design method is generated based on the weight frequency of a path that passes.
(Supplementary Note 14) The network design method according to any one of Supplementary Notes 10 to 13, wherein the priority information is generated when a wavelength cannot be assigned due to the constraint condition.
(Supplementary Note 15) The upper limit number is set based on a value obtained by dividing the number of counted paths by the total number of wavelengths that can be multiplexed into the wavelength multiplexed optical signal by the transmission system. The network design method according to any one of appendices 9 to 14.
(Supplementary note 16) The network design method according to any one of supplementary notes 9 to 15, wherein the upper limit number is corrected in accordance with an external operation.
(Supplementary Note 17) For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, the number of paths passing through the link is counted,
Based on the counted number of paths, for each link, set an upper limit number of transmission systems used to transmit wavelength multiplexed optical signals,
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal Assigning a wavelength to each of the plurality of paths, causing the computer to execute a process;
In the process of assigning a wavelength, when a wavelength cannot be assigned due to the restriction condition (St5), the network design program assigns a wavelength by relaxing the restriction condition.
(Supplementary note 18) When a wavelength cannot be assigned due to the constraint condition, the constraint value is increased by increasing the upper limit value corresponding to the link selected based on priority information indicating the priority of each link. Item 18. The network design program according to item 17, wherein the condition is relaxed.
(Supplementary note 19) The supplementary note 18 is characterized in that the priority information is generated based on a ratio of the number of the paths passing through the link to a total number of wavelengths that can be multiplexed in the wavelength division multiplexed optical signal. Network design program.
(Supplementary Note 20) The priority information is a link in which a predetermined number or more of the paths pass in the network is selected as a congested link, and for each of the links excluding the congested link, of the paths that pass through the link The network design program according to appendix 18 or 19, wherein the network design program is generated based on the number of the paths passing through the congested link.
(Supplementary Note 21) When the network has a plurality of the congested links, the priority information determines, for each path, a weight degree corresponding to the number of the congested links through which the path passes, The network design program according to appendix 20, wherein the network design program is generated based on the weight frequency of a path that passes through the network.
(Supplementary note 22) The network design program according to any one of supplementary notes 18 to 21, wherein the priority information is generated when a wavelength cannot be assigned due to the constraint condition.
(Supplementary Note 23) The upper limit number is set based on a value obtained by dividing the number of counted paths by the total number of wavelengths that can be multiplexed into the wavelength multiplexed optical signal by the transmission system. The network design program according to any one of appendices 17 to 22.
(Supplementary note 24) The network design program according to any one of supplementary notes 17 to 23, wherein the upper limit number is corrected according to an operation from outside.

1 Network design device 10 CPU
DESCRIPTION OF SYMBOLS 100 Count processing part 101 Setting processing part 102 Generation processing part 103 Allocation processing part 133 Priority information 2 Network 20 WDM apparatus 30 Transmission system

Claims (10)

For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, a counting processing unit that counts the number of paths that pass through the link;
Based on the number of paths counted by the counting processing unit, a setting processing unit that sets an upper limit number of transmission systems used for transmitting wavelength division multiplexed optical signals for each link;
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal An allocation processing unit for assigning a wavelength to each of the plurality of paths,
The network design apparatus characterized in that the allocation processing unit relaxes the constraint condition and allocates a wavelength when the wavelength cannot be allocated due to the constraint condition. A generation processing unit that generates priority information indicating the priority of each of the links;
The allocation processing unit relaxes the constraint condition by increasing the upper limit value corresponding to the link selected based on the priority information when a wavelength cannot be allocated due to the constraint condition. The network design apparatus according to claim 1, wherein the apparatus is a network design apparatus.   The said generation process part produces | generates the said priority information based on the ratio of the number of the said paths which pass through the said link with respect to the total number of the wavelengths which can be multiplexed with the said wavelength multiplexing optical signal. The network design device described.   The generation processing unit selects, as a congested link, the link through which a predetermined number or more of the paths pass in the network, and the congested link out of the paths through the link for each link excluding the congested link. The network design device according to claim 2, wherein the priority information is generated based on the number of the paths that pass through the network.   When the network has a plurality of the congested links, the generation processing unit determines, for each path, a weighting degree corresponding to the number of the congested links through which the path passes, and determines the path of the path through the congested links. The network design device according to claim 4, wherein the priority information is generated based on the weight frequency.   The network design device according to claim 2, wherein the generation processing unit generates the priority information when a wavelength cannot be assigned due to the constraint condition.   The setting processing unit determines the upper limit number based on a value obtained by dividing the number of paths counted by the counting processing unit by the total number of wavelengths that can be multiplexed into the wavelength multiplexed optical signal by the transmission system. The network design device according to claim 1, wherein the network design device is set.   The network design device according to claim 1, wherein the setting processing unit corrects the upper limit number according to an operation from outside. For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, the number of paths passing through the link is counted,
Based on the counted number of paths, for each link, set an upper limit number of transmission systems used to transmit wavelength multiplexed optical signals,
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal Assign a wavelength to each of the plurality of paths;
In the process of assigning the wavelength, when a wavelength cannot be assigned due to the constraint condition, the network design method is characterized in that the wavelength is assigned by relaxing the constraint condition. For each link between nodes in a network provided with a plurality of paths through which optical signals of a plurality of wavelengths are transmitted, the number of paths passing through the link is counted,
Based on the counted number of paths, for each link, set an upper limit number of transmission systems used to transmit wavelength multiplexed optical signals,
For each link, the number of optical signals of the same wavelength that can be used redundantly is less than or equal to the upper limit set by the setting processing unit, and the optical signals multiplexed into the wavelength multiplexed optical signal Assigning a wavelength to each of the plurality of paths, causing the computer to execute a process;
In the process of assigning a wavelength, when a wavelength cannot be assigned due to the constraint condition, the network design program allocates a wavelength by relaxing the constraint condition.

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