A method, medium and system for reconstructing spectrum of multicast service based on hybrid grating

Abstract

The present invention discloses a method, medium and system for reconstructing the spectrum of a multicast service based on a hybrid grating, comprising: determining the shortest path from the source node of the multicast service to be run to each destination node each time a first preset number of multicast services are received; obtaining the first frequency slot usage of the multicast service being run in the network and the network; determining the frequency slot position that can be allocated to the multicast service to be run in the shortest path from the source node of the multicast service to be run to each destination node based on the first frequency slot usage of the network; obtaining the second frequency slot usage of the network after the frequency slot position is allocated to the multicast service to be run; calculating the spectrum fragmentation measurement index of the network according to the second frequency slot usage of the network; if the spectrum fragmentation measurement index of the network is greater than the index threshold, reconstructing the spectrum of at least part of the multicast services in the allocated frequency slot position of the network. The present invention reduces the influence of spectrum fragmentation on the allocation of service routing resources.

Description

Technical Field

[0001] The present invention relates to the technical field of multicast services, and in particular to a method, medium and system for reconstructing a multicast service spectrum based on a hybrid grating. Background Art

[0002] At present, the research in the scenario of hybrid grid optical network only has the strategy of spectrum reconstruction for unicast services, but no spectrum reconstruction method for multicast services. Since the routing and forwarding tree of multicast services is relatively large compared with unicast services, and the continuity and consistency requirements need to be met when allocating frequency slots, the degree of spectrum fragmentation will be more serious for hybrid grid optical networks carrying multicast services than for networks carrying unicast services, and the blocking rate of the network will increase. Summary of the invention

[0003] The embodiments of the present invention provide a method, medium and system for reconstructing the spectrum of multicast services based on a hybrid grating, so as to solve the problem that the prior art lacks technology for reconstructing the spectrum of multicast services, resulting in that the degree of spectrum fragmentation of the hybrid grid optical network carrying multicast services is more serious than that of the network carrying unicast services, while increasing the blocking rate of the network.

[0004] In a first aspect, a method for reconstructing a multicast service spectrum based on a hybrid grating is provided, comprising:

[0005] Each time a first preset number of multicast services are received, the shortest path from the source node of the multicast service to be run received this time to each destination node is determined;

[0006] Acquire the multicast service currently running in the network and the usage of the first frequency slot of the network;

[0007] Based on the usage of the first frequency slot of the network, determining the frequency slot position that can be allocated to the multicast service to be run in the shortest path from the source node of the multicast service to be run to each destination node;

[0008] Acquire usage of a second frequency slot of the network after allocating the frequency slot position to the multicast service to be run;

[0009] Calculating a spectrum fragmentation measurement indicator of the network based on usage of a second frequency slot of the network;

[0010] If the spectrum fragmentation measurement index of the network is greater than the index threshold, spectrum reconstruction is performed on at least part of the multicast services at the allocated frequency slot positions of the network.

[0011] In a second aspect, a computer-readable storage medium is provided, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for reconstructing a multicast service spectrum based on a hybrid grating as described in the embodiment of the first aspect above is implemented.

[0012] In a third aspect, a hybrid grating-based multicast service spectrum reconstruction system is provided, comprising: a computer-readable storage medium as described in the above-mentioned second aspect embodiment.

[0013] In this way, the embodiment of the present invention calculates the spectrum fragmentation index and applies it to multicast services, so that spectrum reconstruction can be performed at an appropriate time to reduce the impact of spectrum fragmentation on service routing resource allocation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0015] Figure 1 is a flow chart of a method for reconstructing a multicast service spectrum based on a hybrid grating according to an embodiment of the present invention;

[0016] Figure 2 is a VIII node topology diagram of a specific application example of the present invention;

[0017] Figure 3 is a schematic diagram of the use of frequency slots in a current network according to a specific application example of the present invention;

[0018] Figure 4 It is a schematic diagram of the use of frequency slots in a network after spectrum resources are allocated to MS10 in a specific application example of the present invention;

[0019] Figure 5 is a schematic diagram of a first alternative path of MS8 in a specific application example of the present invention;

[0020] Figure 6 This is a schematic diagram of the first candidate path of MS8 after tree division in a specific application example of the present invention;

[0021] Figure 7 is a spectrum usage diagram when selecting a path in a specific application example of the present invention;

[0022] Figure 8 It is a spectrum usage diagram in the network after MS8 of a specific application example of the present invention performs spectrum reconstruction operation;

[0023] Fig. 9 It is a spectrum usage diagram in the network after MS5 performs spectrum reconstruction operation in a specific application example of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The embodiment of the present invention discloses a method for reconstructing the spectrum of a multicast service based on a hybrid grating, which is applied to an elastic optical network. The network is an optical network around which a fixed grid and a flexible grid coexist, and can also be called a hybrid grid optical network. Considering the different granularities of spectrum resource usage in a hybrid grid optical network, the constraints that need to be met by routing and resource allocation are also different. When a service arrives, appropriate spectrum resources are allocated to establish a transmission connection according to the requirements of spectrum consistency and continuity. After a period of time, the spectrum resources no longer maintain the original neat segmentation, and the smaller spectrum fragments in the optical network cannot be effectively utilized by the service. The messy and disordered state of the spectrum resources makes it impossible to find enough spectrum segments to use when new services arrive, resulting in service congestion. Therefore, in the hybrid grid optical network scenario, a spectrum fragmentation measurement indicator for measuring the state of spectrum fragmentation is proposed, which takes into account the proportion of spectrum fragments in the link and the average number of frequency slots of the service on the link, and uses this as a reference to determine whether it is necessary to reconstruct the spectrum of the running multicast service.

[0026] Specifically, Figure 1 As shown, the method comprises the following steps:

[0027] Step S101: Whenever a first preset number of multicast services are received, the shortest path from the source node of the multicast service to be run received this time to each destination node is determined.

[0028] Specifically, the network includes multiple links, and a link is formed by connecting two nodes in the network. Then the path from the source node to the destination node is formed by connecting at least one link in sequence.

[0029] For example, a multicast service has source node 7, destination nodes 1, 2, and 5. There can be multiple paths from source node 7 to destination node 1, from which the shortest distance is obtained; similarly, there can be multiple paths from source node 7 to destination node 2, from which the shortest distance is obtained; similarly, there can be multiple paths from source node 7 to destination node 5, from which the shortest distance is obtained.

[0030] The first preset number can be set according to experience or actual needs. For example, if the first preset number is 50, when the 50th multicast service is received, the shortest path from the source node of the multicast service to each destination node is determined. For example, the first preset number is 50, and it should be understood that after the 50th multicast service is received, the next received multicast service starts counting from 1; it should also be understood that if the received multicast service is not the 50th, there is no need to perform the operations described in the embodiment of the present invention.

[0031] Step S102: Acquire the multicast service currently running in the network and the usage of the first frequency slot of the network.

[0032] The first frequency slot usage includes: the location of the occupied frequency slots in each link, the number of frequency slots, etc., wherein the occupied frequency slots may be a running multicast service or a fragment.

[0033] Step S103: based on the usage of the first frequency slot of the network, determine the frequency slot position that can be allocated to the multicast service to be run in the shortest path from the source node of the multicast service to be run to each destination node.

[0034] Specifically, the First-Fit algorithm may be used to determine the frequency slot position. The First-Fit algorithm is specifically:

[0035] When allocating spectrum resources, the spectrum resource idle area table is searched sequentially starting from the header until the first idle area that meets the size requirement of the requested multicast service is found. Part of the idle area is allocated to the requested multicast service, and the rest remains in the idle area.

[0036] For example, the source node is 7 and the destination node is 1, then the idle frequency slot position on the path that meets the requirements of the First-Fit algorithm is allocated to the multicast service.

[0037] Step S104: Acquire the usage status of the second frequency slot of the network after the frequency slot position is allocated to the multicast service to be run.

[0038] As above, the second frequency slot usage includes: the position of the occupied frequency slot in each link, the number of frequency slots, etc., wherein the occupied frequency slot may be a running multicast service or a fragment.

[0039] Step S105: Calculate a spectrum fragmentation measurement index of the network according to the usage of the second frequency slot of the network.

[0040] Specifically, the calculation formula for the spectrum fragmentation measurement index of the network is:

[0041]

[0042] Among them, FI represents the spectrum fragmentation measurement index, represents the average number of frequency slots occupied by the multicast service on the ith link, L ij F frag represents the number of frequency slots of the jth fragment on the i-th link, L i F max Indicates the maximum position of the frequency slot currently occupied by the i-th link, L i F used represents the number of currently occupied frequency slots in the i-th link, M represents the total number of fragments in the links of the network, and N represents the total number of links in the network.

[0043] Among them, fragments refer to spectrum blocks that are discontinuous and have a small number of frequency slots. The "small number" mentioned above can be set based on experience and actual conditions. "Discontinuous" means that the frequency slots before and after the spectrum block with a small number of frequency slots are occupied. For example, Figure 3 The 3rd and 4th frequency slots of link 2-0 can be considered as a spectrum block fragment, and the frequency slots before and after these two frequency slots are already occupied. The 1st and 2nd frequency slots of link 7-0 also belong to a spectrum block fragment, and these two frequency slots are the first two frequency slots and the frequency slots after them are already occupied.

[0044] in, It is equal to the quotient of the number of frequency slots occupied by all multicast services on the i-th link and the number of multicast services on the i-th link. Figure 3 For example, Indicates the average number of frequency slots occupied by multicast services on link 2-0. The number of frequency slots occupied by multicast services is 6, and the number of multicast services is 2.

[0045]

[0046] Among them, for L i F max ,by Figure 3 For example, the maximum position of the currently occupied frequency slot of link 2-0 is 8.

[0047] Step S106: If the spectrum fragmentation measurement index of the network is greater than the index threshold, spectrum reconstruction is performed on at least part of the multicast services at the allocated frequency slot positions of the network.

[0048] The method for obtaining the indicator threshold includes:

[0049] (1) The simulation process of receiving multicast services and allocating frequency slots to the received multicast services under different network loads.

[0050] Different network loads can be selected based on experience and actual conditions. It should be understood that the network does not perform spectrum reconstruction operations.

[0051] (2) When the network is congested, the spectrum fragmentation measurement index of the network is calculated.

[0052] It should be understood that network congestion generally refers to that there are not enough frequency slots in the network to be allocated to multicast services, and the network is considered to be congested.

[0053] The spectrum fragmentation measurement index is calculated in the same way as described above and will not be described again here.

[0054] (3) Calculate the average value of the spectrum fragmentation metric calculated under different network loads.

[0055] (4) The calculated average value of the spectrum fragmentation measurement index is used as the index threshold.

[0056] Specifically, this step includes the following process:

[0057] Step 1: If the spectrum fragmentation metric of the network is greater than the metric threshold, then the service metric of each multicast service at the allocated frequency slot position of the network is calculated.

[0058] It should be understood that the multicast services at the allocated frequency slot positions include multicast services that are being run and to be run.

[0059] Specifically, the calculation formula for the business measurement indicator is:

[0060]

[0061] Among them, SI represents the business measurement indicator, SF max Indicates the maximum position of the frequency slot occupied by the multicast service, LF max Indicates the maximum position of the currently occupied frequency slots in all links, that is, the maximum usage position of the frequency slots in all links, SF num Indicates the number of frequency slots required for multicast services, SF mnum represents the maximum number of frequency slots required for multicast services in the network, Δt represents the remaining running time of the multicast service, and Δt max It represents the maximum remaining running time of the multicast service in the network. α, β, and γ represent variable constants, and α+β+γ=1.

[0062] Among them, for SF mnum , refers to the number of frequency slots occupied by the multicast service that occupies the most frequency slots among all the running multicast services. Figure 4 For example, among 10 multicast services, MS8 occupies a total of 20 frequency slots, and the number of frequency slots occupied by other multicast services is less than 20. Then SF mnum =20.

[0063] Step 2: Arrange each multicast service at the allocated frequency slot position of the network in descending order according to their respective service metrics.

[0064] Step 3: Reconstruct the spectrum of the multicast services with a preset percentage before sorting.

[0065] Specifically, this step includes the following process:

[0066] (1) For each multicast service of a preset percentage before sorting, obtain the first second preset number of paths with the shortest path distance for the multicast service as the first candidate paths.

[0067] The preset percentage can be set based on experience. For example, the preset percentage is 20%.

[0068] The second preset number may also be set based on experience. For example, if the second preset number is 3, then for a group of paths of a multicast service, the paths are sorted by distance, and the first three paths with the shortest distance are obtained as the first candidate paths.

[0069] There may be more than one destination node in a multicast service, and the path distance of the multicast service is the sum of the path distances from the source node of the multicast service to each destination node.

[0070] (2) Sort the first candidate paths for the multicast service in ascending order of path distance.

[0071] (3) Perform tree partitioning according to whether the paths from the source node to each destination node in each first candidate path of the multicast service overlap.

[0072] The process of tree splitting includes:

[0073] ① For a first candidate path, determine whether each path in the first candidate path has the same node except the source node.

[0074] ② If each path in the first candidate path has the same nodes except the source node, the first candidate path will not be subjected to tree splitting processing.

[0075] ③ If at least one path in the first candidate path does not have any common nodes with other paths except the source node, the first candidate path is divided into a tree, so that each path in the first candidate path that does not have the same nodes as other paths except the source node is divided into each independent subtree, and the path with the same nodes except the source node is divided into an independent subtree.

[0076] The tree-dividing operation can make the allocation of spectrum resources more flexible and reduce the blocking rate of services.

[0077] For example, Figure 5As shown, the two paths of the first candidate path 1 are 6-7-0-2 and 6-5-4, which do not have the same nodes. Then, the tree is split and the following is obtained: Figure 6 One independent subtree is shown as 6-7-0-2 and another independent subtree is shown as 6-5-4.

[0078] For example, Figure 5 As shown, the two paths of the first candidate path 2 are 6-5-0-2 and 6-5-4, which have the same node 5. Figure 6 No tree splitting is performed as shown.

[0079] For example, the two paths of the first candidate path are 6-7-0, 6-5-0-2 and 6-5-4. 6-7-0 does not have the same nodes as the other two paths, so a tree splitting process is performed to obtain an independent subtree 6-7-0 and another independent subtree 6-5-0-2 and 6-5-4.

[0080] (4) According to the ranking of the first candidate paths of the multicast service, a First-Fit algorithm is used to sequentially determine the position of the frequency slot required by each first candidate path after the multicast service tree division process.

[0081] The First-Fit algorithm has been described above and will not be described again here. It should be understood that when the First-Fit algorithm is used for calculation in this step, it is assumed that the spectrum resources occupied by the original path of the multicast service are released so that the spectrum resources occupied by the original path of the multicast service can be used when the First-Fit algorithm is used for calculation. Therefore, this "release" is not an actual release, but is only processed in the calculation.

[0082] (5) According to the position of the frequency slot required by each first candidate path of the multicast service, a first candidate path that meets the preset requirements is obtained as the second candidate path.

[0083] Specifically, the preset requirements include: spectrum resource allocation meets the conditions of continuity and consistency. Continuity means that the spectrum gaps allocated for each multicast service connection request are continuous with each other without any gaps in between. Consistency means that the allocated spectrum resources are consistent between the previous link and the next link on the established optical path. It should also be understood that continuity and consistency are for a routing tree. If the multicast service does not perform a tree splitting operation during path selection, the paths from the source node to all destination nodes must meet continuity and consistency. If the multicast service performs a tree splitting operation during path selection, the paths in each subtree need to meet continuity and consistency. Several subtrees are independent, and spectrum resource allocation is considered for each subtree separately.

[0084] (6) Obtain the maximum frequency slot position and number of frequency slots required by the second candidate path of the multicast service.

[0085] (7) Compare the size of the maximum frequency slot position required by the second candidate path of the multicast service.

[0086] Depending on the comparison results, there are two processing methods as follows (8) and (9).

[0087] (8) If there is only one second candidate path with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and spectrum resources are re-allocated to the multicast service according to the second candidate path with the smallest maximum frequency slot position.

[0088] (9) If there are at least two second candidate paths with the smallest maximum frequency slot position, the numbers of frequency slots required by the second candidate paths with the smallest maximum frequency slot position are compared.

[0089] Depending on the comparison results, there are two processing methods: (10) and (11).

[0090] (10) If there is only one second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and the spectrum resources are reallocated to the multicast service according to the second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position.

[0091] (11) If there are at least two second alternative paths with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and a second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position is randomly selected to reallocate spectrum resources to the multicast service.

[0092] By reconstructing the multicast service spectrum through the above method, spectrum fragmentation can be reduced, making the occupied spectrum resources more compact.

[0093] The embodiment of the present invention further discloses a computer-readable storage medium having computer program instructions stored thereon; when the computer program instructions are executed by a processor, the method for reconstructing the spectrum of a multicast service based on a hybrid grating as described in the above embodiment is implemented.

[0094] The embodiment of the present invention further discloses a system for reconstructing a multicast service spectrum based on a hybrid grating, comprising: a computer-readable storage medium as described in the above embodiment.

[0095] The technical solution of the present invention is further illustrated below with a specific application example.

[0096] like Figure 2As shown in the figure, a multicast service MS10 (7, {1, 5}, 150) reaches the VIII node topology. The source node of the multicast service is 7, the destination nodes are 1 and 5, and the transmission rate required by the service is 150Gb / s. The transmission rate and transmission distance required by the multicast service determine the number of frequency slots that the multicast service needs to occupy, which is determined by the relationship between the transmission rate of the frequency slot under different modulation levels and the maximum transmission distance. For details, please refer to Table 1. The longest distance of the multicast service path is 400km. According to the relationship between the transmission rate of the frequency slot under different modulation levels and the maximum transmission distance shown in Table 1, the modulation format of 16QAM is selected, and the transmission rate is 50Gb / s. Since the transmission rate required by the multicast service is 150Gb / s, each link needs to occupy three frequency slots.

[0097] Table 1 Transmission rate and maximum transmission distance of frequency slots under different modulation levels

[0098]

[0099]

[0100] First, according to the node topology graph, the shortest paths from the source node to the three destination nodes are obtained as 7-1, 7-1-2 and 7-5 respectively.

[0101] The frequency slot usage in the current network is as follows: Figure 3 As shown. There are nine multicast services currently running in the network, namely MS1(0,{1,2},50), MS2(1,{3,4,6},50), MS3(1,{4,7},100), MS4(2,{0,6},20), MS5(3,{2,5,7},100), MS6(4,{0,6},50), MS7(5,{0,3},50), MS8(6,{2,4},20), MS9(7,{0,1,2},100). The frequency slot position that can be allocated to the multicast service MS10 is determined according to the First-Fit algorithm. After MS10 is allocated spectrum resources, the spectrum usage in the network is as follows: Figure 4 shown.

[0102] Then, based on the frequency slot usage of the current network, the spectrum fragmentation measurement index FI value of the current network is calculated, and FI≈0.1832 is obtained. Index threshold FI block is 0.18, the current FI value exceeds FI block , it is necessary to reconfigure the spectrum of a portion of the multicast services currently running in the network.

[0103] First, the service measurement index SI value is calculated for the multicast services in the allocated frequency slot position in the network and sorted in descending order. Assuming that the remaining running time of the services in the network is the same at this time, the influence of the remaining running time is not considered temporarily, α=β=1 / 2, and the calculation results are: SI 1 ≈0.3667; SI 2 ≈0.3833; SI 3 ≈0.5917; SI 4 ≈0.4333; SI 5 =0.8333; SI 6 ≈0.4667; SI 7 ≈0.4667; SI 8 =1; SI 9 ≈0.3167; SI 10 ≈0.4417. Assuming the current preset percentage λ% is 20%, it is necessary to reconstruct the spectrum of the first two services, namely MS8 and MS5.

[0104] First, spectrum reconstruction is performed on MS8 (6, {2, 4}, 20). Assuming the current second preset number k is 3, the three shortest paths from source node 6 to destination node 2 are obtained, which are 6-7-1-2, 6-7-0-2, and 6-5-0-2, and the three shortest paths from source node 6 to destination node 4 are obtained, which are 6-5-4, 6-7-0-4, and 6-5-0-4. The three shortest paths to the two destination nodes are combined, and the sum of the distances of the combined paths is calculated. The three shortest paths with the smallest sum of distances are obtained as the first candidate paths. Specifically, the first candidate path 1 of the multicast service is 6-7-0-2 and 6-5-4, the first candidate path 2 is 6-5-0-2 and 6-5-4, and the first candidate path 3 is 6-7-1-2 and 6-7-0-4. It should be understood that, because the original paths of MS8 are 6-7-1-2 and 6-5-4, the first candidate path selected for reconstruction cannot be exactly the same as the original path, so the first candidate path 3 is 6-7-0-4. Sort the paths in ascending order according to their length, such as Figure 5 The three first candidate paths are divided into trees according to whether they overlap. After the division, each subtree is as follows Figure 6 shown.

[0105] According to the order of the first candidate path, the First-Fit method is used to determine the positions of the allocated frequency slots in turn, starting from Figure 7 It can be seen that the three first candidate paths all meet the preset requirements and can be used as second candidate paths. The maximum frequency slot position and the required number of frequency slots occupied by each second candidate path are recorded, such as Figure 7 As shown. Figure 7It can be seen that the maximum frequency slot position of the frequency slot occupied by the second alternative path 1 is 8, and the number of frequency slots required is 20; the maximum frequency slot position of the frequency slot occupied by the second alternative path 2 is 8, and the number of frequency slots required is 16; the maximum frequency slot position of the frequency slot occupied by the second alternative path 3 is 12, and the number of frequency slots required is 20. Comparing the maximum positions of the frequency slots occupied by the three second alternative paths, the maximum frequency slot positions of the second alternative paths 1 and 2 are the smallest and the same, then the size of the number of frequency slots required by the second alternative paths 1 and 2 is compared, and the path with the smallest number of frequency slots is selected. Therefore, it can be seen that the second alternative path 2 is selected.

[0106] Release the spectrum resources occupied by the original path of MS8, re-allocate the spectrum resources according to the second alternative path 2, re-establish the connection and update the network status. After MS8 performs the spectrum reconstruction operation, the spectrum usage diagram in the network is as follows: Figure 8 shown.

[0107] Similarly, after performing the above process on MS5, the spectrum usage diagram after spectrum reconstruction can be obtained as shown in Fig. 9 shown.

[0108] contrast Figure 4 and Figure 8 It can be seen that performing spectrum reconstruction operation can reduce spectrum fragmentation and make the occupied spectrum resources more compact.

[0109] In summary, the embodiment of the present invention proposes a spectrum fragmentation measurement index in the hybrid grid optical network scenario, and uses this as a reference to determine whether to perform spectrum reconstruction on the running multicast service. This evaluation index comprehensively considers the proportion of spectrum fragments and the average frequency gap of the service on the link; in addition, the spectrum reconstruction process of the embodiment of the present invention compares multiple alternative paths and selects a relatively more suitable path to carry the service. The spectrum reconstruction operation reduces spectrum fragmentation, improves the utilization rate of spectrum resources, and can also improve the service blocking situation to a certain extent.

[0110] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for reconstructing a multicast service spectrum based on a hybrid grating, characterized in that: include: Each time a first preset number of multicast services are received, the shortest path from the source node of the multicast service to be run received this time to each destination node is determined; Acquire the multicast service running in the network and the usage of the first frequency slot of the network; Based on the usage of the first frequency slot of the network, determining the frequency slot position that can be allocated to the multicast service to be run in the shortest path from the source node of the multicast service to be run to each destination node; Acquire usage of a second frequency slot of the network after allocating the frequency slot position to the multicast service to be run; Calculating a spectrum fragmentation measurement indicator of the network based on usage of a second frequency slot of the network; If the spectrum fragmentation measurement index of the network is greater than the index threshold, reconstructing the spectrum of at least part of the multicast services at the allocated frequency slot position of the network; The calculation formula of the spectrum fragmentation measurement index is: ； in, FI represents the spectrum fragmentation measure, Indicates i The average number of frequency slots occupied by multicast services in the links, Indicates i The first link in j The number of frequency slots per fragment, Indicates i The maximum position of the currently occupied frequency slot in the links, Indicates i The number of currently occupied frequency slots in the links, M Represents the total number of fragments in the links of the network, N Represents the total number of links in the network; The network includes a plurality of links, wherein the link is formed by connecting two nodes in the network.

2. The method for reconstructing the spectrum of multicast services based on hybrid grating according to claim 1, characterized in that: The step of reconfiguring the spectrum of at least part of the multicast services at the allocated frequency slot position of the network comprises: If the spectrum fragmentation measurement index of the network is greater than the index threshold, calculating the service measurement index of each multicast service at the allocated frequency slot position of the network; Arranging each of the multicast services at the allocated frequency slot position of the network in descending order according to the respective service measurement indicators; The spectrum of the multicast services of a preset percentage before sorting is reconstructed.

3. The multicast service spectrum reconstruction method according to claim 2, characterized in that: The calculation formula of the business measurement indicator is: ； in, SI represents a business metric, Indicates the maximum position of the frequency slot occupied by the multicast service. Indicates the maximum position of the currently occupied frequency slot in all links. Indicates the number of frequency slots required for multicast services, Indicates the maximum number of frequency slots required for multicast services in the network. Indicates the remaining running time of the multicast service. Indicates the maximum remaining running time of the multicast service in the network. α , β , γ represents a variable constant, α + β + γ =1.

4. The method for reconstructing the spectrum of multicast services based on hybrid grating according to claim 2, characterized in that: The step of reconfiguring the spectrum of the multicast services of a preset percentage before sorting includes: For each of the multicast services of a preset percentage before sorting, obtaining a second preset number of paths with the shortest path distances for the multicast service as first candidate paths; Sort the first candidate paths of the multicast service in ascending order of path distance; Perform tree splitting processing according to whether the paths from the source node to each destination node in each first candidate path of the multicast service overlap; According to the order of the first candidate paths of the multicast service, the First-Fit algorithm is used to sequentially determine the position of the frequency slot required for each first candidate path after the multicast service tree processing, wherein when the First-Fit algorithm is used for calculation, it is assumed that the spectrum resources occupied by the original path of the multicast service are released, so that the spectrum resources occupied by the original path of the multicast service can be used when the First-Fit algorithm is used for calculation; According to the position of the frequency slot required by each first candidate path of the multicast service, obtaining a first candidate path that meets the preset requirements as the second candidate path; Obtaining a maximum frequency slot position and a number of frequency slots required by a second candidate path of the multicast service; Compare the size of the maximum frequency slot position required by the second candidate path of the multicast service; If there is only one second candidate path with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and spectrum resources are reallocated to the multicast service according to the second candidate path with the smallest maximum frequency slot position.

5. The method for reconstructing the spectrum of multicast services based on hybrid grating according to claim 4, characterized in that: After the step of comparing the size of the maximum frequency slot position required by the second candidate path of the multicast service, the method further includes: If there are at least two second candidate paths with the smallest maximum frequency slot position, comparing the number of frequency slots required by the second candidate path with the smallest maximum frequency slot position; If there is only one second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and spectrum resources are re-allocated to the multicast service according to the second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position; If there are at least two second alternative paths with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position, the spectrum resources occupied by the original path of the multicast service are released, and a second alternative path with the smallest number of frequency slots among the second alternative paths with the smallest maximum frequency slot position is randomly selected to reallocate spectrum resources to the multicast service.

6. The method for reconstructing the spectrum of multicast services based on hybrid grating according to claim 4, characterized in that: The path distance of the multicast service is the sum of the path distances from the source node to each destination node of the multicast service.

7. The method for reconstructing the spectrum of multicast services based on hybrid grating according to claim 1, characterized in that: The method for obtaining the indicator threshold includes: The simulation process of receiving multicast services and allocating frequency slots to the received multicast services is performed on the network under different network loads, wherein the network does not perform spectrum reconstruction operation; When congestion occurs in the network, calculating a spectrum fragmentation measurement indicator of the network; Calculating an average value of the spectrum fragmentation measurement indicator calculated under the different network loads; The calculated average value of the spectrum fragmentation measurement index is used as the index threshold.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by the processor, the method for reconstructing the spectrum of multicast services based on hybrid gratings as described in any one of claims 1 to 7 is implemented.

9. A multicast service spectrum reconstruction system based on hybrid grating, characterized in that: include: The computer readable storage medium of claim 8.

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