JP5835737B2 - Method for determining path and frequency band - Google Patents

Description

  The present invention relates to a method for determining a path and a frequency band between nodes that transmit and receive optical signals on a network in which a plurality of nodes are connected by optical fibers.

  An elastic optical path network has been proposed in which a minimum frequency band corresponding to the transmission capacity of an optical signal is allocated to a path between nodes that transmit and receive optical signals on a network in which a plurality of nodes are connected by optical fibers. (For example, see Non-Patent Document 1). The frequency band allocated to the elastic optical path network is not allocated based on the frequency grid in which the optical path is a fixed frequency interval as in the conventional optical path network, but a certain frequency width is set to one slot unit. The number of slots is determined flexibly.

  For example, in a network in which the frequency interval is fixed at 50 GHz, when there is a communication demand with a transmission capacity corresponding to 20 GHz, a frequency band of only 50 GHz is consumed. On the other hand, in the elastic optical path network, for example, two slots of 12.5 GHz units can be allocated to the communication demand, and the remaining frequency band can be allocated to other communication demands. For this reason, the elastic optical path network can use frequency resources effectively.

  On the other hand, an optical path network design method in which shared protection is introduced has been proposed (for example, see Non-Patent Document 2). In shared protection, a working path used as a path for transmitting and receiving an optical signal and a backup path used when the working path fails are provided, and a part of the backup path is shared between the working paths. By doing so, it is possible to reduce a required amount of fiber such as the number of optical fibers to be prepared for the backup path and frequency resources in the fiber. For this reason, an optical fiber resource can be used effectively by adopting an optical path network design method in which shared protection is introduced.

  FIG. 15 shows an example of an optical path network in which shared protection is introduced. A plurality of nodes 91a to 91k are connected by optical fibers. When the optical signal is transmitted from the node 91a to the node 91d and the optical signal is transmitted from the node 91e to the node 91k, the optical path is transmitted from the node 91a to the node 91d and the optical signal is transmitted from the node 91e to the node 91k. The working path 93Uek is independent. Also, a backup path 93Fad independent of the current path 93Uad and a backup path 93Fek independent of the current path 93Uek are provided. The backup path 93Fad and the backup path 93Fek share the nodes 91f, 91g, and 91h. The link from 91f to the node 91h is shared.

  Introducing shared protection in an elastic optical path network leads to effective use of frequency resources and optical fiber resources. In this case, there are restrictions for configuring an elastic optical path network and restrictions for introducing shared protection, and both of these restrictions must be satisfied.

  For example, in an elastic optical path network, the same slot constraint that the same set of slots must be used from the start point to the end point of the route, and the slot collision constraint that one slot cannot be assigned to multiple communication demands in the same fiber There is a restriction that. On the other hand, in the shared protection, there is a restriction that the working routes in different grounds must be made independent, and the working route and the backup route in the same ground have to be made independent. Here, the fact that the working routes are independent means that the nodes include the start point and the end point of the route and do not share any nodes. The fact that the active route and the backup route are independent means that no node is shared except the start point and the end point of these routes.

Masahiko Jinno, Bartlomiej Kozicki, Hidehiko Takara, Atsushi Watanabe, Yoshiaki Sone, Takafumi Tanaka, and Akira Hirano, "Distance-Adaptive Spectrum Resource Allocation in Spectrum-Sliced Elastic Optical Path Network", IEEE Communications Magazine, PP. 138-145, August 2010 Pin-Han Ho, Hussein T .; Moftah, “Shared Protection in Mesh WDM Networks”, IEEE Communications Magazine, PP. 70-76, January 2004 Xu Shao, Yong-Kee Yeo, Zhaowen Xu, Xiaofei Cheng, Luying Zhou, “Shared-Path Protection in OFDM-basic Optical Networks with EC”. Ramesh Bandari, “Survivable Networks”, KLUWER ACADEMI PUBLISHERS, PP. 175-182, 1999 Jane M.J. Simmons, “Optical network Design and Planning”, Springer, P. et al. 68, 2008

  When sharing protection is introduced in an elastic optical path network, it is preferable that the frequency sharing of the frequency slot is high for the backup path, but it is necessary to consider the restrictions of the elastic optical path.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the frequency slot sharing degree of a backup path in an elastic optical path network in which shared protection is introduced.

The path and frequency band determination method of the present invention is an error in which a frequency band corresponding to the transmission capacity of an optical signal is allocated to a path between nodes transmitting and receiving the optical signal on a network in which a plurality of nodes are connected by optical fibers. A method for determining a route and a frequency band using a stick optical path network, wherein a working route enumeration procedure for enumerating current route candidates including a combination of a start point and an end point between the nodes and a required number of frequency slots, and a working route For each of these candidates, a backup route determination procedure for determining a backup route independent of the current route, and for the determined backup route , frequency slots with consecutive numbers satisfying the same slot constraint and the slot collision constraint with the current route are satisfied. slot continuous constraints satisfied, and the frequency slots are shared with other preparatory routes it largely be assigned As such, using the frequency slot determination procedure for determining a frequency slot, a frequency slot of the spare path and the spare path was determined for each active route, from among the listed working path, the required fiber in the working path and the protection path And a working route determination procedure for determining a working route so that the amount of resources is reduced.

  In the path and frequency band determination method of the present invention, the ratio of the frequency slots shared with other backup paths from among the backup paths used in the current path determined in the current path determination procedure is the other backup paths. The spare path that is smaller or the unused frequency slot is accommodated in the optical fiber larger than the other optical fiber, and the working path of the spare path are removed, and the removed working path and spare path are determined again. A reassignment procedure to be performed may be further provided after the working route determination procedure.

  In the reassignment procedure, the removed working route and protection route may be determined again by executing the working route enumeration procedure, the protection route determination procedure, the frequency slot determination procedure, and the working route determination procedure.

The route and frequency band determination program of the present invention is an error that allocates a frequency band according to the transmission capacity of an optical signal to a path between nodes that transmit and receive the optical signal on a network in which a plurality of nodes are connected by optical fibers. A program for determining a path and a frequency band using a stick optical path network, wherein a working path listing unit enumerates working path candidates including a combination of a start point and an end point between the nodes and a necessary number of frequency slots. The enumeration procedure, the backup route determination unit determines a backup route independent of the current route for each candidate of the current route, and the same slot constraint for the backup route determined by the frequency slot determination unit. A slot that satisfies the slot collision constraint with the working path and assigns consecutive numbered frequency slots. Continuous constraints satisfied, and as a frequency slot that is shared with other preparatory route is large, the frequency slot decision procedure for determining the frequency slot, the working path determination unit, spare path and the preliminary determined for each working path Using the frequency slot of the path, the computer sequentially executes a working path determination procedure for determining the working path so that the required resource amount of the fiber in the working path and the backup path is reduced from the listed working paths.

  ADVANTAGE OF THE INVENTION According to this invention, the sharing degree of the frequency slot of a backup path | route can be improved in the elastic optical path network which introduced the shared protection.

2 shows an example of a network according to the first embodiment. 1 illustrates an example of a configuration of a path and frequency band determination device according to a first embodiment. 3 is a flowchart illustrating an example of a route and frequency band determination method according to the first embodiment. It is an explanatory view of cost c _j ^b according to the first embodiment. An example of a working route and a backup route when assignment of all traffic patterns according to the first embodiment is completed is shown. An example of the structure of the determination apparatus of the path | route and frequency band which concerns on Embodiment 2 is shown. 10 shows a first example of a reallocation procedure according to Embodiment 2. It is an explanatory view of sharing of R _d of the frequency slots. It is an illustration of utilization F _d of the fiber. It is explanatory drawing of reduction of a fiber. The 2nd example of the reallocation procedure concerning this embodiment is shown. The 3rd example of the reallocation procedure which concerns on this embodiment is shown. An example of the working path and the backup path after finishing the reassignment procedure is shown. An example of the comparison result of the number of required fibers between the invention of Embodiment 2 and the conventional invention is shown. An example of an optical path network with shared protection introduced.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 1 shows an example of a network according to this embodiment. In the present embodiment, as an example, in a network in which a plurality of nodes 91-01 to 91-25 are connected by optical fibers, a traffic pattern 1 for transmitting an optical signal from the node 91-01 to the node 91-17, and a node 91 A case of having a traffic pattern 2 for transmitting an optical signal from -03 to a node 91-15 and a traffic pattern 3 for transmitting an optical signal from a node 91-09 to a node 91-23 will be described.

  The path and frequency band determination method according to the present embodiment is an ITSA (Iterative Two Step) process in which a frequency band corresponding to the transmission capacity of an optical signal is allocated to a path between nodes transmitting and receiving an optical signal on a network. The route is determined using (Approach). Specifically, the route and frequency band determination method according to the present embodiment includes an active route enumeration procedure, a backup route determination procedure, a frequency slot determination procedure, and an active route determination procedure in this order.

  FIG. 2 shows an example of a path and frequency band determining apparatus according to this embodiment. The path and frequency band determining apparatus according to the present embodiment includes a working path listing unit 11 that executes a working path listing procedure, a backup path determining unit 12 that executes a backup path determining procedure, and a frequency that executes a frequency slot determining procedure. A slot determining unit 13 and a working route determining unit 14 for executing a working route determining procedure are provided. The route and frequency band determining apparatus according to the present embodiment includes a computer program for determining a route and frequency band determining program that functions as the working route listing unit 11, the backup route determining unit 12, the frequency slot determining unit 13, and the working route determining unit 14. You may implement | achieve by making it perform.

  In the working route listing procedure, the working route listing unit 11 lists candidates for working routes between nodes. In the backup route determination procedure, the backup route determination unit 12 determines a backup route independent of the current route for each candidate of the current route. In the frequency slot determination procedure, the frequency slot determination unit 13 determines a frequency slot for the determined backup path so that the frequency slot shared with other backup paths becomes large. In the working route determination procedure, the working route determination unit 14 determines a working route with the smallest amount of fiber resources from the listed working routes. By executing these procedures, when a new communication demand is allocated, a path having a combination of a route and a frequency slot can be selected so that a required amount of fiber resources is reduced.

  FIG. 3 is a flowchart illustrating an example of a route and frequency band determination method according to the present embodiment. In step S101, one traffic pattern is extracted. The traffic pattern includes a combination of start and end points and the required number of frequency slots. The combination of the start point and the end point is, for example, the node 91-01 that is the start point of the traffic pattern 1 and the node 91-17 that is the end point.

  In step S102, the working route enumeration unit 11 enumerates the candidates for the working route by searching for a route connecting the start point and the end point. For example, a list of routes that can be reached from the node 91-01 to the node 91-17 is listed. The candidate for the working route is searched using, for example, a K-shortest-path algorithm.

  In step S103, the backup route determination unit 12 selects one of the working route candidates. At this time, frequency slots are selected so as to satisfy the same slot constraint and slot collision constraint. In addition, the slot continuation constraint for assigning consecutive numbered frequency slots is also satisfied. This satisfies the constraints for configuring an elastic optical path network.

  The K-shortest-path algorithm is an algorithm that extracts K routes in the order of shortest route among routes connecting a start point and an end point (see, for example, Non-Patent Document 4). When two paths are extracted from the node 91-01 to the node 91-17 using the above algorithm, for example, the paths 91-01, 91-06, 91-11, 91-16, 91-17, The routes -01, 91-06, 91-11, 91-12, and 91-17 are extracted.

  In step S104, the protection route determination unit 12 restricts the shared protection in which the working routes in different grounds are independent of the selected working route and the working route and backup route in the same ground are independent. A backup route that satisfies the conditions is determined. For example, one shortest route independent of the working route is obtained. The shortest path is calculated using, for example, the Dijkstra method (see, for example, Non-Patent Document 5). When the current route candidates are 91-01, 91-02, 91-07, 91-12, 91-17, the Dijkstra method is used, and the backup routes are 91-01, 91-06, 91-11, 91. -16 and 91-17 are selected.

  In step S105, the frequency slot determination unit 13 sets the cost of the working route and the backup route candidate to the maximum value. The cost is determined by the number of frequency slots and the number of hops. The maximum value is set to be larger than the product of the maximum number of frequency slots that can be assumed and the maximum value of the number of hops.

  In steps S106 to S110, the frequency slot determination unit 13 determines a frequency slot that minimizes the cost when the backup path determined in step S104 is used while shifting the frequency slot number. For example, the cost is calculated for each link of the working path and the backup path, and the total cost of each link is obtained as the fiber cost (S107). Then, the cost value is updated so that the fiber cost becomes the smallest among the costs calculated so far (S108, S109). By scanning this up to the last slot number (S110), the frequency slot number that minimizes the fiber cost is determined.

Here, the cost c _j ^w of the working path and the cost c _j ^b of the backup path of each link are expressed by the following equations, for example.
(Formula 1)
c _j ^w = n _d ^{w
_{c j b = n d b -b}} i + ε
Here, n _d ^w and n _d ^b are the frequency slots of the working path and backup path of d, respectively, and b _i is the other of n _d ^b slot sets counted from the i-th in the fiber j. Ε is a sufficiently small positive number such that 0 <ε <1 to prevent c _j ^{b from} becoming zero. The cost may be infinite if the required number of slots cannot be secured for the route or slot number being examined, or if the working routes are not independent and the slots cannot be shared.

  FIG. 4 shows an example of cost calculation when a backup path with three slots is set for links L1 to L3 with six slots. The cost for each link is calculated for a total of four times from i = 0 to i = 3. In this example, when i = 2, the cost of the backup path becomes the minimum, and the fiber cost is calculated by adding the cost of the working path to this.

The backup route determination unit 12 and the frequency slot determination unit 13 perform steps S103 to S110 for all the active route candidates listed in step S102 (S111).
In step S113, the working route determination unit 14 selects the working and backup routes and the frequency slot of the route with the lowest cost among all the working routes listed in step S102 with respect to the traffic pattern extracted in step S101. (S113). For example, the working path and the protection path are determined such that the sum of the cost of the working path obtained in step S103 and the cost of the minimum protection path obtained in steps S106 to S110 is minimized. As a result, when the traffic pattern d = 1, the working cost and the spare capacity in which the fiber cost is minimized, that is, the amount of fiber resources to be used is the smallest in the list of working paths that can reach the node 91-17 from the node 91-01 A path can be assigned.

  If there is a link that needs to add an optical fiber in order to realize a combination of a path and a frequency slot when the fiber cost is minimized, the optical fiber is added to the link (S112).

  The working route listing unit 11, the backup route determining unit 12, the frequency slot determining unit 13 and the working route determining unit 14 also perform steps S101 to S113 for other traffic patterns. In this embodiment, steps S101 to S113 are also performed for the route from the node 91-03 to the node 91-15 with the traffic pattern d = 2 and the route from the node 91-09 to the node 91-23 with the traffic pattern d = 3. The combination of path and frequency slot when the fiber cost is minimized is assigned to the working path and the backup path.

  FIG. 5 shows an example of the working route and the backup route when assignment of all traffic patterns according to the present embodiment is completed. The working paths 93U1, 93U2, and 93U3 are independent of the path from the node 91-01 to the node 91-17, the path from the node 91-03 to the node 91-15, and the path from the node 91-09 to the node 91-23. Yes, the working path and the backup path are independent of each other, and the links of the nodes 91-08 and 91-13 in the backup paths 93R2 and 93R3 are shared.

  The combination of the working paths 93U1, 93U2 and 93U3 and the backup paths 93R1, 93R2 and 93R3 is selected to minimize the fiber cost. For this reason, the path and frequency band determination method according to the present embodiment can reduce the amount of frequency resources in the fiber used in the elastic optical path network in which shared protection is introduced.

(Embodiment 2)
In the present embodiment, a route with a low share of the frequency slot for the backup route or a route accommodated in an optical fiber with a low utilization rate is removed and reaccommodated with ITSA. Therefore, the route and frequency band determination method according to the present embodiment further includes a reallocation procedure after the working route determination procedure.

  FIG. 6 shows an example of a path and frequency band determining apparatus according to this embodiment. The route and frequency band determination device according to the present embodiment further includes a reassignment unit 15 that executes a reassignment procedure after the working route determination unit 14 described in the first embodiment. The reassignment unit 15 includes a share degree calculation unit 51, a share degree reassignment unit 52, a fiber utilization rate calculation unit 53, and a fiber utilization rate reassignment unit 54. The path and frequency band determination device according to the present embodiment includes a working path enumeration 11, a backup path determination unit 12, a frequency slot determination unit 13, a working path determination part 14, and a path and frequency band determination that functions as a reallocation unit 15. The program may be realized by causing a computer to execute the program.

  In the reassignment procedure, the reassignment unit 15 selects a spare route having a low frequency slot sharing ratio from the spare route used in the working route determined in the working route determination procedure and the working route of the spare route or the fiber route. The backup path included in the fiber having a low utilization rate and the working path of the via path are removed, and the removed working path and backup path are determined again.

FIG. 7 shows a first example of the reallocation procedure according to this embodiment. The re-assignment procedure, obtains the shared degree R _d of the frequency slots for all the backup path sharing degree calculator 51 (S702), the working and backup path sharing degree reallocation unit 52 having a smaller backup path sharing of R _d Is removed from the network (S703). The frequency slot sharing degree represents the extent to which the backup path shares the frequency slot with other backup paths, that is, the ratio of the frequency band shared with other backup paths. For this reason, in step S703, a backup path having a small proportion of the frequency band shared with other backup paths is removed from the network. Then, the share reassignment unit 52 aggregates the remaining backup paths between the parallel fibers in the same link, and if possible, reduces the fibers (S704). Then, the working path and the protection path removed by the sharing degree reallocation unit 52 are rearranged using ITSA (S705). That is, the rearrangement in step S705 re-determines the removed working path and protection path by executing the working path enumeration procedure, the backup path determination procedure, the frequency slot determination procedure, and the work path determination procedure.

Next, the fiber usage rate calculation unit 53 calculates the fiber usage rate for all the fibers (S706), and the fiber usage rate reallocation unit 54 removes a path with a low fiber usage rate from the network (S707). The fiber utilization rate represents how many frequency slots are continuously used in one fiber. For this reason, in step S707, a path included in a fiber having more unused slots than other fibers is removed from the network. Then, the fiber utilization rate reallocation unit 54 aggregates the remaining paths among the parallel fibers in the same link, and if possible, reduces the fibers (S708). Then, the fiber utilization rate reallocation unit 54 rearranges the removed working path and protection path using ITSA (S709). That is, in the rearrangement in step S709, the removed working path and protection path are determined again by executing the working path enumeration procedure, the protection path determination procedure, the frequency slot determination procedure, and the working route determination procedure.
Steps S702 to S709 are repeated a specified number of times (S710).

周波数スロットの共有度Ｒ_ｄが大きい予備パスほど共有度が大きく、周波数スロットの共有度Ｒ_ｄが小さい予備パスほど共有度が小さい。 Here, the shared degree R _d of the frequency slot in step S702, share the slot traffic pattern d, the number of hops of the protection path h _d, the preparatory route r _b, the link (fiber) l in path If the average value of the number of paths (including d itself) and s _l, for example, is expressed by the following equation.

Large share of R _d is too large backup path sharing of the frequency slot, a small share of the more backup path sharing of R _d is small frequency slot.

For example, as shown in FIG. 8, when there is a link shared by the backup path 1 with the frequency slot number 5 and the protection path 2 with the frequency slot number 3, the slot is shared with the protection path 1 in the link. The average value s _{l of the} number of existing paths is (1 + 1 + 2 + 2 + 2) /5=1.6, and the average value s _{1 of the} number of paths sharing the slot with the backup path 2 is (2 + 2). +2) /3=2.0. By calculating s _l in each link of the protection path 1 and dividing the sum of these s _{1 by} the number of hops of the protection path 1, the frequency slot sharing degree R _d of the protection path 1 can be calculated.

Ｆ_ｄの値が小さいほどファイバの利用率が高くなり、Ｆ_ｄの値が大きいほどファイバの利用率が低くなる。 Further, the utilization rate F _d of the fiber in step S706, the total number of traffic patterns d, the active route r _w, the preparatory route r _b, the unused link in the path (the fiber) l, in link l frequency slot And the total number of sets of unused consecutive frequency slots is represented by E ₁ , for example.

The value of F _d becomes high utilization of the smaller fibers, utilization as the value of F _d is greater fiber is lowered.

For example, as shown in FIG. 9, in a link 1 having 16 frequency slots, frequency slots with slot numbers # 1 to # 4, # 8, # 9, # 12, # 14, and # 15 are used, and the other When the frequency slots are unused, the total number of unused frequency slots is 7, and the number of sets of unused continuous frequency slots is 4. Therefore, _El is 7 + 4 = 11.

Here, the usage rate F _d of the fiber is calculated for both the working path and the protection path. For example, if the traffic pattern d = 1, E _l is calculated for each fiber l of both the working path 93U1 and the backup path 93R1 shown in FIG. 5, and the smallest value among these E _l is set to the fiber utilization rate F. Calculate as _d .

E _l in Equation 2 may be used the number of usage between adjacent slots is reversed. For example, as shown in FIG. 9, between slot numbers # 4 and # 5, between slot numbers # 7 and # 8, between slot numbers # 9 and # 10, between slot numbers # 11 and # 12, When the usage status is inverted between the numbers # 12 and # 13, between the slot numbers # 13 and # 14, and between the slot numbers # 15 and # 16, the usage status is inverted seven times. E _l = 7.

E _l in Equation 2 may be used the total number of unused slots. For example, in the example of FIG. 9, since the total number of unused frequency slots is 7, E _l = 7.

E _l in Equation 2, the number of times usage between adjacent slots is inverted, may be calculated using the product of the total number of unused slots. For example, as shown in FIG. 9, when the total number of unused frequency slots is 7, and the number of times the usage status is inverted between adjacent slots is 7, _El is 7 × 7 = 49.

  The fiber reduction in steps S704 and S708 will be described with reference to FIG. Two optical fibers are arranged in parallel, the path 1 of the working path and the path 2 of the backup path are allocated to one optical fiber, the path 3 of the backup path is allocated to the other optical fiber, and the path 1 And the frequency slot of path 2 is different, and the frequency slot of path 2 is included in the frequency slot of path 2. In this state, when the path 2 is removed in step S703 or S707, the path 3 optical fiber becomes unnecessary by moving the backup path 3 between the parallel fibers. In such a case, optical fibers are reduced in steps S704 and S708.

The number of paths to be removed in steps S703 and S707 may be constant, but is not limited thereto.
For example, a constant rate P1 path with low frequency slot sharing may be removed in step S703, and a constant rate P2 path with low fiber utilization may be removed in step S707.
Further, after the second iteration, the rate of removal may be reduced in proportion to the number of iterations, and finally the rate may be zero. Thereby, the processing time of steps S704, S705, S708, and S709 is reduced.
The fixed ratios P1 and P2 may be determined experimentally.

  Further, the number of paths to be removed in steps S703 and S707 and the number of repetitions in step S710 are set to arbitrary fixed values. After step S710, the number of fibers required at the end of step S709 is the smallest in each repetition. There may be further provided a procedure for determining an active path and a backup path and a path of a combination of these frequency slots. For example, when the number of repetitions is 10, the number of required fibers in the network configuration after the allocation in step S709 for 10 times is compared.

  Also, instead of step S710, the necessary number of fibers at the end of step S709 is recorded, and when the number of required fibers at the end of the previous step S709 is greater than the end of the previous step S709. The current route and the backup route and the combination of these frequency slots may be determined at the time. For example, if the number of repetitions is 10, the number of required fibers for the eighth time is 12, and the number of required fibers for the ninth time is 14, the route is determined to be the eighth time.

11 and 12 show a second example and a third example of the reallocation procedure according to the present embodiment.
As shown in FIG. 11, in the reassignment procedure, steps S706 to S709 may be removed, and reassignment based on only the protection path sharing degree may be performed. Conversely, as shown in FIG. 12, in the reassignment procedure, steps S702 to S705 may be removed, and reassignment based only on the fiber utilization rate may be performed.

  FIG. 13 shows an example of the working route and the backup route after the reassignment procedure is finished. The backup path 93R1 shown in FIG. 5 is not shared with any backup path, and in addition to the low frequency slot sharing rate, the fiber utilization rate is also low. However, by performing the reassignment procedure and rearranging the path 1 from the node 91-01 to the node 91-17, as shown in FIG. 13, the frequency slot sharing degree of the backup route 93R1 can be increased.

  In the 5 × 5 lattice topology shown in FIGS. 1, 5, and 13, the traffic pattern to be removed in steps S <b> 703 and S <b> 707 is set to a constant ratio (P1, P2) = (0.1, 0.5), and is repeated in step S <b> 710. FIG. 14 shows the result of comparing the required number of fibers with the conventional method (see Non-Patent Document 3) with the designated number of times being 100. For the required number of fibers calculated using the method described in this embodiment and the required number of fibers obtained by the method described in Non-Patent Document 3, an average value is obtained when uniform random traffic is generated 20 times. The value which divided the required number of fibers calculated using the method demonstrated by this embodiment by the required number of fibers calculated | required with the method of a nonpatent literature 3 is shown. By using the method described in the present embodiment, as shown in FIG. 14, the number of optical fibers can be reduced by up to 8% from the required number of fibers obtained by the technique described in Non-Patent Document 3.

  The present invention can be applied to the information communication industry.

11: Working route listing unit 12: Backup route determining unit 13: Frequency slot determining unit 14: Working route determining unit 15: Reallocating unit 51: Sharing degree calculating unit 52: Sharing degree reallocating unit 53: Fiber utilization rate calculating unit 54 : Fiber utilization rate reallocation units 91-01 to 91-25, 91a to 91k: Nodes 93U1, 93U2, 93U3, 93Uad, 93Uek: Working paths 93R1, 93R2, 93R3, 93Fad, 93Fek: Backup paths

Claims (4)

In a network in which a plurality of nodes are connected by optical fibers, a path and frequency band using an elastic optical path network that allocates a frequency band corresponding to the transmission capacity of the optical signal to a path between nodes that transmit and receive optical signals. A decision method,
A working path enumeration procedure for enumerating current path candidates including a combination of a start point and an end point between the nodes and a required number of frequency slots ;
A backup route determination procedure for determining a backup route independent of the current route for each candidate of the current route;
The determined backup route satisfies the same slot constraint and the slot collision constraint with the working route, satisfies the slot continuation constraint for assigning consecutive numbered frequency slots, and increases the frequency slot shared with other backup routes. to a frequency slot decision procedure for determining the frequency slot,
Using the backup path determined for each work path and the frequency slot of the backup path, the work path is determined from the enumerated work paths so that the required resources of the fiber in the work path and the backup path are reduced. Decision procedure;
A method of determining a path and a frequency band that have a sequence of Of the spare paths used in the working path determined in the working path determination procedure, a spare path whose frequency slot share with other spare paths is smaller than other spare paths or an unused frequency slot A reassignment procedure in which the backup path accommodated in an optical fiber larger than the other optical fiber and the working path of the backup path are removed, and the removed working path and backup path are determined again.
The method according to claim 1, further comprising after the working route determination procedure. In the reassignment procedure,
3. The removed working route and backup route are determined again by executing the working route listing procedure, the backup route determining procedure, the frequency slot determining procedure, and the working route determining procedure. Method of determining the path and frequency band of In a network in which a plurality of nodes are connected by optical fibers, a path and frequency band using an elastic optical path network that allocates a frequency band corresponding to the transmission capacity of the optical signal to a path between nodes that transmit and receive optical signals. A decision program,
A working path enumeration unit that enumerates working path candidates including a combination of a start point and an end point between the nodes and a necessary number of frequency slots ;
A backup route determination unit for determining a backup route independent of the current route for each candidate of the current route;
The frequency slot determination unit satisfies the same slot constraint and the slot collision constraint with the working route for the determined backup route , and also satisfies the slot continuation constraint for assigning consecutive numbered frequency slots, and is shared with other backup routes A frequency slot determination procedure for determining a frequency slot so that the frequency slot becomes large;
The working path determination unit uses the spare path determined for each working path and the frequency slot of the spare path so that the required resources of the fiber in the working path and the spare path are reduced from the listed working paths. A working route determination procedure for determining a route;
A program for determining a path and a frequency band for causing a computer to execute the processes in order.

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