Service request spectrum resource allocation method in elastic optical network

Abstract

The invention relates to the technical field of elastic optical network resource allocation, and discloses a service request spectrum resource allocation method in an elastic optical network, which comprises the following steps of: initializing the elastic optical network and a group of request services to be allocated; dividing the current to-be-allocated request service reaching the elastic optical network into an instant reservation request and an advanced reservation request; for the instant reservation request, performing service construction according to the arrival time of the instant reservation request and the computing resource of the corresponding destination node; for the advance reservation request, constructing a priority evaluation function based on the number of spectrum slots required by the task, the duration time and the maximum tolerable delay time, and performing service construction based on the priority; and a special protection path which is not intersected with the target working path is established for the target working path of each service request, so that a double-path protection mechanism is realized. According to the method and the system, resources are reasonably allocated through distinguishing the service request types, constructing the priority function and setting a dual-path protection mechanism, so that the network transmission reliability and survivability are improved, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of elastic optical network resource allocation, and in particular to a method for allocating spectrum resources for service requests in an elastic optical network. Background Art

[0002] In elastic optical networks, requests that need to be served immediately upon arrival are called immediate reservation service requests, and requests that allow a certain degree of initial delay during service connection establishment are called advance reservation service requests.

[0003] In the modern network environment, the rise of data center applications such as data migration and cloud computing has posed new challenges to the traditional flexible optical network spectrum resource model, and it has become particularly important to improve spectrum utilization and transmission efficiency. With the rapid increase in bandwidth demand and the exponential growth in the number of connection requests, traditional network resource allocation methods can no longer meet existing needs, especially when dealing with a large number of immediate reservations and advance reservation service requests. The popularity of smartphones has made mobile data account for a large proportion of total Internet traffic. Emerging applications such as cloud computing, video on demand, and online games have triggered an explosion of online information, bringing a large amount of content and high network traffic. In this case, how to effectively classify and process these connection requests to improve the efficiency of the network system has become a hot topic in optical network research.

[0004] In order to cope with different types of requests, improving network performance and providing more reliable and efficient network services has become a major challenge. Immediate reservation service requests require that services be provided immediately after the connection request arrives, which places high demands on the real-time response capability of the network. In contrast, advance reservation service requests allow a certain degree of initial delay and can allocate spectrum resources before the scheduled deadline. There are differences in resource requirements and service times between immediate reservation service requests and advance reservation service requests, and how to balance resource allocation between them becomes a key issue. If resources are not allocated reasonably, network performance may be degraded and user needs may not be met.

[0005] Routing and spectrum allocation in elastic optical networks are core issues. The effective use of spectrum resources is directly related to the network's operating efficiency and service quality. Optical fiber spectrum resources consist of continuous time slots with fixed spectrum widths. Traditional network models have proposed some methods for routing, modulation, and spectrum allocation. However, these methods often fail to fully consider the needs of handling different types of reserved services. In an environment with diverse bandwidth requirements, traditional methods only consider the arrival time of reserved service requests when evaluating resource allocation priorities. This single-dimensional evaluation method ignores other important factors, such as capacity requirements, service duration, and maximum tolerable delay time. Therefore, the efficiency of resource allocation may be affected, some requests may not be processed in a timely manner, or the allocated resources may not be reasonable, resulting in a decrease in the overall utilization and transmission efficiency of the network.

[0006] In summary, when dealing with a large number of simultaneous immediate reservation and advance reservation service requests, traditional spectrum-flexible optical network resource allocation methods only consider the arrival time of services, and often fail to effectively allocate spectrum resources. This limitation not only affects the overall performance of the network, but may also cause some service requests to not be processed in a timely manner, thus affecting the user experience. Summary of the invention

[0007] To this end, the technical problem to be solved by the present invention is to overcome the problem in the prior art that only the arrival time of service requests is considered to allocate spectrum resources, resulting in poor resource utilization, low network performance, and affecting user experience.

[0008] In order to solve the above technical problems, the present invention provides a method for allocating spectrum resources for service requests in an elastic optical network, comprising: Initialize the elastic optical network, obtain the node set, optical fiber link set, physical distance set between adjacent nodes, available spectrum slot number set of optical fiber link and foreseeable time slot number set of the network in the elastic optical network; Obtain a set of request services to be allocated, and obtain the computing resource requirements of each request service to be allocated in the set, including the source node, destination node, capacity requirement, arrival time, maximum tolerable delay time and request duration; For each requested service to be allocated that arrives at the elastic optical network, based on its arrival time and the maximum tolerable delay time, the type of each requested service to be allocated is obtained; the type includes an immediate reservation request and an advance reservation request; Determine whether the destination node corresponding to the current request service to be allocated that arrives at the elastic optical network meets the computing resource requirements of the current request service to be allocated: If not, the establishment of the current requested service to be allocated fails; If it is satisfied, the K shortest paths algorithm is used to select K candidate paths from the source node to the destination node for the current request task to be assigned; all candidate paths are sorted in the order of the product of the number of spectrum slots required by each candidate path and the number of nodes on the candidate path from small to large to obtain a candidate path set; in the candidate path set, it is determined whether there is a candidate path that meets the spectrum consistency constraint, spectrum continuity constraint and time continuity constraint: If it exists, the first candidate path in the candidate path set that satisfies the spectrum consistency constraint, the spectrum continuity constraint, and the time continuity constraint is taken as the target working path; If not, based on the arrival time of the current request service to be allocated and the maximum tolerable delay time, determine whether the current request service to be allocated is an advance reservation request: If the current request service to be allocated is an immediate reservation request, the establishment of the current request service to be allocated fails; If the current request to be allocated is an advance reservation request, the current request to be allocated is placed in the reallocation request set; In the reallocation request set, based on the number of spectrum slots, duration and maximum tolerable delay time required by each request task to be allocated, a priority evaluation function of each request task to be allocated is constructed to obtain a priority function value of each request task to be allocated; According to the order of priority function values ​​from large to small, for each request task to be assigned in the reallocation request set, determine whether the waiting time of the request task to be assigned exceeds the maximum tolerable delay time corresponding to the request task to be assigned: If it exceeds, the establishment of the service to be allocated request fails; If it does not exceed, then within the maximum tolerable delay time of the request service to be allocated, a target working path is selected from the K cache candidate paths for the request service to be allocated; After obtaining the target working path of the current request service to be allocated, use the K shortest path algorithm to select K protection paths that do not intersect with the target working path for the current request service to be allocated, and select the protection path with the smallest product of the number of spectrum slots and the number of nodes on the path and satisfying the spectrum consistency constraint, spectrum continuity constraint and time continuity constraint as the dedicated protection path; Based on the target working path and the dedicated protection path of the current requested service to be allocated, a spectrum is allocated to the current requested service to be allocated, thereby completing the establishment of the current requested service to be allocated.

[0009] Preferably, the elastic optical network , expressed as: ; in, represents a set of nodes in an elastic optical network; represents a set of fiber links; Represents the set of physical distances between adjacent nodes; It represents the set of available spectrum slots of the optical fiber link, expressed as , Indicates the elastic optical network The number of available spectrum slots in a fiber link, , Indicates the total number of fiber links in the elastic optical network; Represents the set of foreseeable time slots in the network, expressed as , Indicates The number of foreseeable time slots in the time-sensitive elastic optical network, , Indicates the number of moments in a resource allocation cycle.

[0010] Preferably, the request service to be allocated , expressed as: ; in, Indicates the source node of the requested service to be allocated, Indicates the destination node of the requested service to be allocated; Indicates the capacity requirement of the requested service to be allocated, Indicates the arrival time of the requested service to be allocated, Indicates the maximum tolerable delay time of the requested service to be allocated; Indicates the requested duration of the requested service to be allocated, which is an integer multiple of the unit time slot.

[0011] Preferably, judging whether the current request service to be allocated is an advance reservation request based on the arrival time of the current request service to be allocated and the maximum tolerable delay time includes: If the current request service is to be allocated Arrival time Equal to the actual start time of spectrum allocation , and the maximum tolerable delay time If it is 0, the current request service is to be allocated. For immediate reservation requests , expressed as: ; If the current request service is to be allocated Arrival time Less than the actual start time of spectrum allocation , or the maximum tolerable delay If it is greater than 0, the current request service is to be allocated. To reserve a request in advance , expressed as: .

[0012] Preferably, based on the number of spectrum slots, duration and maximum tolerable delay time required by each request task to be assigned, a priority evaluation function for each request task to be assigned is constructed, including: Based on the modulation level, capacity requirement and bandwidth capacity of each request service to be allocated, the number of spectrum slots required for each request task to be allocated is obtained; Calculate the product of the modulation format and duration of the request task to be assigned as a resource requirement size measurement function of the request task to be assigned; Calculate the inverse of the maximum tolerable delay time of the request task to be assigned as a measurement function of the resource demand urgency of the request task to be assigned; The product of the resource requirement size measurement function and the resource requirement urgency measurement function of each request task to be assigned is calculated as the priority evaluation function of the request task to be assigned.

[0013] Preferably, based on the modulation level, capacity requirement and bandwidth capacity of each request service to be allocated, the number of spectrum slots required for each request task to be allocated is obtained, which is expressed as: ; in, represents the number of spectrum slots required for the requested task to be assigned, Indicates the capacity requirement of the requested service to be allocated; Indicates the modulation level determined according to the actual physical transmission distance of the requested service to be allocated; represents the basic bandwidth of the spectrum slot, Indicates the protection bandwidth.

[0014] Preferably, the product of the modulation format and the duration of the request task to be allocated is calculated as a resource requirement size measurement function of the request task to be allocated, which is expressed as: ; in, represents the resource requirement size measurement function, represents the number of spectrum slots required for the requested task to be assigned, Indicates duration.

[0015] Preferably, the inverse of the maximum tolerable delay time of the request task to be assigned is calculated as a resource demand urgency measurement function of the request task to be assigned, which is expressed as: ; in, represents the resource demand urgency measurement function, Indicates the maximum tolerable delay time.

[0016] Preferably, the product of the resource requirement size measurement function and the resource requirement urgency measurement function of each request task to be assigned is calculated as the priority evaluation function of the request task to be assigned, which is expressed as: .

[0017] Preferably, after the service request to be allocated is completed, it also includes: releasing occupied resources, and updating spectrum resources and node computing resources of the optical fiber link in the elastic optical network.

[0018] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The spectrum resource allocation method for service requests in an elastic optical network described in the present invention divides the current request services to be allocated that reach the elastic optical network into immediate reservation requests and advance reservation requests, and executes the corresponding resource allocation method based on the service request type; for the immediate reservation request, the service is constructed according to its arrival time and the computing resources of the corresponding destination node; for the advance reservation request, a priority evaluation function is constructed based on the number of spectrum slots required for its task, the duration and the maximum tolerable delay time, and the service is constructed based on the priority; the present invention takes into account the differences in resource requirements and service time between requests of different service types, improves the rationality of resource allocation, and improves network performance; and the priority evaluation function constructed by the present invention, compared with the traditional method that only considers a single spectrum dimension, can more comprehensively reflect the actual demand of the request services to be allocated for network resources. At the same time, based on time domain resources and frequency domain resources, the capacity demand and duration of the service requests to be allocated are considered, and the priority of each service request is dynamically adjusted, and spectrum resources are flexibly allocated to the service requests in the reallocation request set, thereby improving network adaptability and flexibility, maintaining efficient resource utilization under different network load conditions, reducing network congestion rate, and improving user experience.

[0019] After obtaining the target working path of the service request to be allocated, the present invention establishes a non-intersecting dedicated protection path for each target working path of the service request, thereby realizing a dual-path protection mechanism; if the target working path of the service request to be allocated fails during service establishment, the corresponding dedicated protection path can be called to realize instant recovery of service establishment, thereby improving the transmission reliability, survivability and service stability of the network and enhancing user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 It is a flowchart of the steps of the method for allocating spectrum resources for service requests in an elastic optical network provided by the present invention; Figure 2 It is the NSFNET network topology diagram; Figure 3 It is a schematic diagram of computing resource requirements for pre-reserving business requests; Figure 4 It is another diagram of computing resource requirements for pre-reserving business requests. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0022] Reference Figure 1 As shown, the flowchart of the method for allocating spectrum resources for service requests in an elastic optical network provided by the present invention includes the following specific steps: S101: Initialize the elastic optical network, obtain a set of nodes, a set of optical fiber links, a set of physical distances between adjacent nodes, a set of available spectrum slots of optical fiber links, and a set of foreseeable time slots of the network in the elastic optical network; Elastic Optical Network , expressed as: ; in, represents a set of nodes in an elastic optical network; represents a set of fiber links; Represents the set of physical distances between adjacent nodes; It represents the set of available spectrum slots of the optical fiber link, expressed as , Indicates the elastic optical network The number of available spectrum slots in a fiber link, , Indicates the total number of fiber links in the elastic optical network; Represents the set of foreseeable time slots in the network, expressed as , Indicates The number of foreseeable time slots in the time-sensitive elastic optical network, , Indicates the number of moments in a resource allocation cycle.

[0023] S102: Obtain a set of request services to be allocated, and obtain computing resource requirements of each request service to be allocated in the set, including a source node, a destination node, a capacity requirement, an arrival time, a maximum tolerable delay time, and a request duration; Request business to be allocated , expressed as: ; in, Indicates the source node of the requested service to be allocated, Indicates the destination node of the requested service to be allocated; Indicates the capacity requirement of the requested service to be allocated, Indicates the arrival time of the requested service to be allocated, Indicates the maximum tolerable delay time of the requested service to be allocated; Indicates the requested duration of the requested service to be allocated, which is an integer multiple of the unit time slot.

[0024] S103: for each requested service to be allocated that arrives at the elastic optical network, based on its arrival time and the maximum tolerable delay time, obtaining the type of each requested service to be allocated; the type includes an immediate reservation request and an advance reservation request; S104: Determine whether the destination node corresponding to the current request service to be allocated that arrives at the elastic optical network meets the computing resource requirements of the current request service to be allocated: S104-1: If not satisfied, the establishment of the current requested service to be allocated fails; S104-2: If the conditions are met, K shortest paths algorithm is used to select K candidate paths from the source node to the destination node for the current request task to be assigned; all candidate paths are sorted in ascending order according to the product of the number of spectrum slots required by each candidate path and the number of nodes on the candidate path, to obtain a candidate path set; S105: In the candidate path set, determine whether there is a candidate path that satisfies the spectrum consistency constraint, the spectrum continuity constraint, and the time continuity constraint: S105-1: If so, the first candidate path in the candidate path set that satisfies the spectrum consistency constraint, the spectrum continuity constraint, and the time continuity constraint is used as the target working path; S105-2: If not, determine whether the current request service to be allocated is an advance reservation request based on the arrival time of the current request service to be allocated and the maximum tolerable delay time: S106: If the current request service to be allocated is an immediate reservation request, the establishment of the current request service to be allocated fails; S107: If the current request service to be allocated is an advance reservation request, the current request to be allocated is placed in a reallocation request set; S108: In the reallocation request set, based on the number of spectrum slots, duration and maximum tolerable delay time required by each request task to be allocated, construct a priority evaluation function for each request task to be allocated, and obtain a priority function value for each request task to be allocated; S109: for each request task to be allocated in the reallocation request set, in descending order of the priority function value, determine whether the waiting time of the request task to be allocated exceeds the maximum tolerable delay time corresponding to the request task to be allocated: S109-1: If it exceeds, the establishment of the service to be allocated fails; If not, then within the maximum tolerable delay time of the request service to be allocated, S109-2: select a target working path from the K cache candidate paths for the request service to be allocated; S110: After obtaining the target working path of the current request service to be allocated, select K protection paths that do not intersect with the target working path for the current request service to be allocated using the K shortest path algorithm, and select a protection path with the smallest product of the number of spectrum slots and the number of nodes on the path and satisfying spectrum consistency constraints, spectrum continuity constraints, and time continuity constraints as the dedicated protection path; S111: Allocate spectrum to the current requested service to be allocated based on the target working path and the dedicated protection path of the current requested service to be allocated, and complete the establishment of the current requested service to be allocated.

[0025] Specifically, in the embodiment of the present invention, based on the arrival time of the current request service to be allocated and the maximum tolerable delay time, determining whether the current request service to be allocated is an advance reservation request includes: If the current request service is to be allocated Arrival time Equal to the actual start time of spectrum allocation , and the maximum tolerable delay time If it is 0, the current request service is to be allocated. For immediate reservation requests , expressed as: ; If the current request service is to be allocated Arrival time Less than the actual start time of spectrum allocation , or the maximum tolerable delay If it is greater than 0, the current request service is to be allocated. To reserve a request in advance , expressed as: .

[0026] Specifically, in the advance reservation request, the maximum tolerable delay time reflects the urgency of the spectrum resource allocation. By scheduling the spectrum resources in the network and allocating the available spectrum resources to such requests before the maximum tolerable delay time, the problems of high blocking rate and low spectrum utilization caused by the arrival of a large number of connection requests in a short period of time can be significantly improved. According to the urgency of different service requests, the advance reservation service requests can be further classified. According to the tolerable delay characteristics of the reservation service request, a more reasonable network resource scheduling is achieved in the elastic optical network system to meet the needs of different types of services.

[0027] Specifically, in step S108 of this embodiment, the process of constructing the priority evaluation function includes: S108-1: Based on the modulation level, capacity requirement and bandwidth capacity of each request service to be allocated, the number of spectrum slots required for each request task to be allocated is obtained, which is expressed as: ; in, represents the number of spectrum slots required for the requested task to be assigned, Indicates the capacity requirement of the requested service to be allocated; Indicates the modulation level determined according to the actual physical transmission distance of the requested service to be allocated; represents the basic bandwidth of the spectrum slot, Indicates the protection bandwidth.

[0028] S108-2: Calculate the product of the modulation format and duration of the request task to be assigned as a resource requirement size measurement function of the request task to be assigned, expressed as: ; in, represents the resource requirement size measurement function, represents the number of spectrum slots required for the requested task to be assigned, Indicates duration.

[0029] S108-3: Calculate the inverse of the maximum tolerable delay time of the request task to be assigned as the resource demand urgency measurement function of the request task to be assigned, expressed as: ; in, represents the resource demand urgency measurement function, Indicates the maximum tolerable delay time.

[0030] S108-4: Calculate the product of the resource requirement size measurement function and the resource requirement urgency measurement function of each request task to be assigned as the priority evaluation function of the request task to be assigned, expressed as: .

[0031] The present invention is mainly devoted to solving the routing and spectrum allocation problems of two different types of connection requests in elastic optical networks, namely, immediate reservation and advance reservation service requests. In elastic optical networks, a certain number of reserved time slots can be foreseen, and the length of each time slot is the same. Based on the resource model, an allocation method for two different types of requests including immediate reservation and advance reservation services is proposed. In an environment with diverse bandwidth requirements, the traditional method only considers the arrival time of the reservation service request for the priority evaluation of resource allocation. This single-dimensional evaluation method may cause resource allocation efficiency problems. Therefore, in view of the fact that the immediate reservation service and the advance reservation service have different processing times for spectrum resources, the concept of tolerable delay time is introduced to solve the resource allocation problem of different reservation service requests; at the same time, a resource allocation priority evaluation method that comprehensively considers capacity requirements, service duration and maximum tolerable delay time is proposed.

[0032] Specifically, in the embodiment of the present invention, the candidate paths need to satisfy three constraints, including: ① Spectrum consistency constraint means that in an elastic optical network, the same spectrum resources should be allocated to the data stream passing through each link in the network; this constraint ensures that the optical signal will not be interrupted or errors will occur during the transmission process due to inconsistent spectrum resources; if the optical nodes through which the optical path passes cannot perform spectrum conversion, then the same frequency slot resources should be used on all links through which the optical path passes; if no continuous and consistent frequency slot resources can be found on the path, it will cause current business congestion, affecting the performance and efficiency of the network.

[0033] ② Spectrum continuity constraint means that the spectrum resources occupied by the same service data flow in the network link should use continuous frequency slots; this constraint ensures that the data flow will not be interrupted or erroneous during transmission due to the discontinuity of spectrum resources; in elastic optical networks, in order to meet the bandwidth requirements of services, a certain number of continuous frequency slot resources need to be allocated to the services; if continuous frequency slot resources cannot be found, it will cause service congestion and reduce the resource utilization efficiency of the network.

[0034] ③ Time continuity constraint means that in the mixed service resource allocation problem of the optical network, the time slot occupied by any data flow on the allocated wavelength must be continuous, ensuring that the data flow will not be interrupted or erroneous during transmission due to discontinuity of time resources.

[0035] Based on the above embodiment, in the embodiment of the present invention, after the service request to be allocated is completed, it also includes: releasing occupied resources, updating the spectrum resources and node computing resources of the optical fiber link in the elastic optical network. At the same time, after the resources are released, the network performance indicators such as the network blocking rate and resource spectrum utilization rate of the elastic optical network are calculated to evaluate the resource allocation method provided by the present invention.

[0036] The spectrum resource allocation method for service requests in the elastic optical network provided by the present invention adopts a reserved service priority evaluation method that comprehensively considers capacity requirements, service duration and maximum tolerable delay time in order to allocate resources more comprehensively and accurately, and improves the evaluation method of the traditional single spectrum dimension, which can more comprehensively reflect the actual demand of each service request for network resources, thereby optimizing resource allocation, reducing resource waste and improving resource utilization efficiency. The present invention not only constructs a new priority evaluation method to optimize resource allocation efficiency, but also designs a dedicated path protection method for resource allocation, and enhances the transmission reliability of the network by simultaneously establishing a working path and a link-disjoint protection path for each service request; this dual-path protection mechanism ensures that even in the case of failure of the main path, the service request can still be smoothly transmitted through the backup path, thereby improving the survivability and service stability of the network. In addition, this evaluation method can dynamically adapt to network needs; by combining the request capacity requirements and duration, high-priority requests are given priority, so that resource allocation can flexibly respond to changes in reserved service requests; this dynamic adaptability not only improves the adaptability and flexibility of the network, but also maintains efficient resource utilization under different network load conditions. Moreover, the evaluation method proposed in the present invention fully reflects the resource consumption of capacity demand and service duration in the two-dimensional time-frequency domain resource model, and optimizes the allocation of network resources in combination with the maximum tolerable delay time; this optimization method not only improves the utilization efficiency of spectrum resources, but also can maximize the satisfaction of various business request requirements under limited resource conditions; the new priority evaluation method not only improves the traditional single-dimensional evaluation method through comprehensive consideration of multiple dimensions, making resource allocation more accurate and comprehensive, but also can significantly improve the survivability, adaptability and overall performance of the network through strategies such as dynamic adaptation and dual-path protection; this method provides an efficient, flexible and reliable solution for resource management in modern complex network environments.

[0037] Based on the above embodiments, in the embodiments of the present invention, the maximum tolerable delay time of the advance reservation service request also reflects the urgency of the request for network resources to a certain extent. The traditional method only uses the time factor as the resource allocation priority evaluation standard, which may cause efficiency problems in resource allocation when facing complex scenarios where the bandwidth requirements of resource reservation requests change. Sorting requests according to the arrival time of the reserved service request may result in the inability to fully utilize the available spectrum resources of the network. Over-emphasizing delay sensitivity may result in applications that have low delay requirements but high bandwidth requirements being unable to obtain sufficient network resources, causing resource allocation balance problems. Therefore, the present invention proposes a reserved service resource allocation priority evaluation method that comprehensively considers capacity requirements C, service duration Ht, and maximum tolerable delay time tdmax to determine the priority of advance reservation service requests in the resource scheduling and allocation process, ensuring efficient use of resources. Specifically, the spectrum resource allocation method for service requests in an elastic optical network provided by the embodiment of the present invention is used to optimize dedicated path protection resources, and the specific steps include: S201: Initialize the elastic optical network, which is expressed as: ; in, Represents the set of nodes in the network, represents a set of fiber links, represents the number of spectrum slots available in each fiber link, By Collection It consists of a set of physical distances between each pair of adjacent nodes in . For example, is the actual distance between node i and node j in the network. A set representing the number of time slots that can be expected in the network.

[0038] S202: Generate a set of connection requests; CR represents the set of connection requests. For each connection request in CR ; s Indicates the source node of the connection request, d Indicates the destination node of the connection request. C Represents the connection request capacity; is the arrival time of the connection request, is the maximum tolerable delay time for a connection request; is the duration of the request, based on the duration The time slot that the request needs to occupy can be calculated. If the advance reservation request does not have a clear duration, then for , and occupies all reserved time slots of the spectrum slot in the network during this period before the service request is released.

[0039] S203: When the service request arrives at the elastic optical network, the spectrum slot bandwidth capacity of the current service request can be expressed as Gb / s, F is the modulation level determined by the actual physical transmission distance of the current service request. is the basic bandwidth of the spectrum slot. In the routing and spectrum allocation problem, the number of spectrum slots required for the service request is determined by the appropriate modulation format selected for the arrival request, taking into account the physical distance between adjacent nodes. , expressed as: ; in, is the amount of protection bandwidth. It indicates the modulation level determined according to the actual physical transmission distance of the requested service to be allocated, and the determination method is: according to the actual physical transmission distance of the requested service to be allocated, the corresponding modulation format is selected, and the preset modulation level corresponding to the modulation format is obtained; for example, when the selected modulation formats are BPSK, QPSK, 8-QAM and 16-QAM, respectively, the corresponding modulation levels are 1, 2, 3 and 4 respectively.

[0040] S204: Use the K shortest path algorithm to calculate the working path for the service request. Sort the candidate paths according to the product of the number of required spectrum slots and the number of transmission path nodes, and give priority to paths with relatively low spectrum resource consumption as transmission routes. The calculated candidate paths are stored in the path set. If a working path cannot be established, the service request is blocked. When a high-priority path is blocked on a certain link, lower-priority paths are selected in turn for spectrum resource allocation until resources are allocated successfully or all paths are blocked.

[0041] S205: In order to handle both immediate reservation and advance reservation service requests in the network, the size of each time slot is fixed. A certain number of reserved time slots can be foreseen in the elastic optical network, and the length of each time slot is the same. In addition, the duration of the service request is an integer multiple of the unit time slot, and the actual start time of the request for spectrum allocation is Only at the initial arrival time Distinguish between advance booking and immediate reservation requests, including: If the arrival time of the current request is equal to the actual start time of spectrum allocation and the maximum tolerable delay time is 0, the current request is an immediate reservation request. , expressed as: ; If the arrival time of the current request is less than the actual start time of spectrum allocation, or the maximum tolerable delay time is greater than 0, the current request is an advance reservation request. , expressed as: .

[0042] S206: Considering the elastic optical network routing, modulation and spectrum allocation issues, the number of spectrum slots required for the service request , depends not only on the bandwidth requirements of the service request according to the physical distance between adjacent nodes and the modulation format, but also on the duration. Therefore, the function for evaluating the resource allocation requirement size of the AR service request is expressed as: ; For the maximum tolerable delay time of the advance reservation service request, a measurement function is designed to measure the urgency of the resource demand for the advance reservation service request. ,For requests with shorter maximum tolerable delay time, the demand for resource allocation is more urgent and should be processed first. At the same time, considering the efficiency of the evaluation method, the resource demand urgency measurement function is Defined as: ; In order to more accurately reflect the priority of resource allocation in the elastic optical network, and optimize resource allocation, the priority evaluation function is used. To represent the priority of advance reservation service request for resource allocation in the two-dimensional time-frequency domain resource model. Priority evaluation function Defined as: ; S207: For an immediate reservation service request, at the service arrival time of the connection request If there is not enough available spectrum resource allocation, it will be blocked immediately.

[0043] S208: For the advance reservation service request within the maximum tolerable delay time, reallocate the request set within the tolerable delay time R A Calculate the priority evaluation value of each request PF And sort and determine the set R A Priority of requesting resource allocation in the request. Before the maximum tolerable delay time expires, if there are available resources that meet the constraints of spectrum continuity, spectrum consistency and time continuity of resource allocation, K shortest paths are used to request to establish a working path and a dedicated protection path with disjoint links, and spectrum allocation is performed respectively according to the algorithm proposed in the present invention, and the service request spectrum allocation is successful. If the maximum tolerable delay time is exceeded, the service is blocked and the set is updated. R A .

[0044] The present invention introduces a priority evaluation method for service request capacity requirements and duration, which can dynamically adapt to the changing characteristics of different service requests. For example, for service requests that require large capacity and long-term continuous connection, the system can reserve more resources in advance to ensure its stable operation; and for short-term and high-frequency small-capacity service requests, the system can flexibly schedule resources to improve overall resource utilization efficiency. The application of this evaluation method can significantly improve the accuracy and flexibility of network resource allocation. By dynamically adjusting the resource allocation strategy, not only can the user experience be improved, but also the network operating costs can be effectively reduced. Especially in the face of complex and changeable network environments, this method can significantly improve the network's response speed and service quality, making network resource allocation more intelligent and efficient, thereby meeting ever-changing business needs and user expectations.

[0045] In the elastic optical network resource allocation method of the present invention, a working path and a link-disjoint backup protection path are simultaneously established for each service request, and spectrum resources are reserved for the two paths, thereby ensuring that when a single point failure occurs during service request transmission, data transmission can be switched from the main path to the backup protection path to achieve instant service recovery. The above-mentioned dedicated path protection method improves the transmission reliability of the network, and combines the capacity requirements of the reserved service request, the service duration, and the allocation priority evaluation method of the maximum tolerable delay time to achieve reasonable allocation of spectrum resources and solve the network survivability and resource optimization problems.

[0046] Specifically, refer to Figure 2 The NSFNET network topology diagram shown has 14 nodes and 21 bidirectional links. The value on the fiber link indicates the physical distance of the link in km. The bandwidth of each spectrum slot is set to 12.5 GHz, the capacity of the fiber link is 120 frequency slots, and the maximum foreseeable number of time slots in the elastic optical network is 20. Generate the requested capacity range C 12.5 Gb / s -200 Gb / s , using different modulation format levels respectively.

[0047] Reference Figure 3 As shown, it is a schematic diagram of computing resource requirements for pre-reserved business requests; refer to Figure 4 As shown in FIG. 1 , another schematic diagram of computing resource requirements for pre-reserved service requests is shown. When there are two AR service requests in the queue waiting for resource allocation, Figure 3 The first advance reservation service request shown AR 1 Capacity requirements C 150Gb / s, duration H t The maximum tolerable delay time is 4 units of time. td max is 2 units of time. Figure 4 The second advance reservation service request shown AR 2 Capacity requirements C 100Gb / s, duration H t The maximum tolerable delay is 2 and 3 time units respectively. Assuming that the candidate paths for the two requests are the same, the bandwidth granularity of the spectrum slot is C slot The data rate is set to 12.5 Gb / s, and the value of the protection bandwidth GB is 1. The 16-QAM modulation format is used, that is, the value of M is 4. The priority evaluation function constructed according to this embodiment can obtain the first advance reservation service request AR 1 The priority evaluation function value is: Similarly, the second advance reservation service request AR 2 The priority evaluation function value is: . Priority evaluation function value PF The larger the value, the higher the resource allocation priority of the request. PF The value of reflects the impact of the capacity requirements of advance reservation service requests and service duration on resource occupancy, and takes into account the urgency of the request for resource allocation, thereby optimizing the allocation of network resources and improving the utilization efficiency of network resources.

[0048] Traditional resource allocation methods only use the arrival time of service requests as the criterion for service priority assessment, which cannot meet the network needs of dynamically changing service requests that need to be reserved in advance. By introducing a priority evaluation method that combines request capacity requirements and duration, high-priority requests can be met first, thereby allocating network resources more reasonably. This method can not only effectively manage resources during peak request periods to avoid over-allocation or under-allocation of resources, but also ensure the continuity and stability of important services during non-peak periods.

[0049] The spectrum resource allocation method for service requests in an elastic optical network described in the present invention divides the current request services to be allocated that reach the elastic optical network into immediate reservation requests and advance reservation requests, and executes the corresponding resource allocation method based on the service request type; for the immediate reservation request, the service is constructed according to its arrival time and the computing resources of the corresponding destination node; for the advance reservation request, a priority evaluation function is constructed based on the number of spectrum slots required for its task, the duration and the maximum tolerable delay time, and the service is constructed based on the priority; the present invention takes into account the differences in resource requirements and service time between requests of different service types, improves the rationality of resource allocation, and improves network performance; and the priority evaluation function constructed by the present invention, compared with the traditional method that only considers a single spectrum dimension, can more comprehensively reflect the actual demand of the request services to be allocated for network resources. At the same time, based on time domain resources and frequency domain resources, the capacity demand and duration of the service requests to be allocated are considered, and the priority of each service request is dynamically adjusted, and spectrum resources are flexibly allocated to the service requests in the reallocation request set, thereby improving network adaptability and flexibility, maintaining efficient resource utilization under different network load conditions, reducing network congestion rate, and improving user experience. After obtaining the target working path of the service request to be allocated, the present invention establishes a non-intersecting dedicated protection path for each target working path of the service request, thereby realizing a dual-path protection mechanism; if the target working path of the service request to be allocated fails during service establishment, the corresponding dedicated protection path can be called to realize instant recovery of service establishment, thereby improving the transmission reliability, survivability and service stability of the network and enhancing user experience.

[0050] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0051] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0052] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0053] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0054] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for allocating spectrum resources for service requests in an elastic optical network, characterized in that: include: Initialize the elastic optical network, obtain the node set, optical fiber link set, physical distance set between adjacent nodes, available spectrum slot number set of optical fiber link and foreseeable time slot number set of the network in the elastic optical network; Obtain a set of request services to be allocated, and obtain the computing resource requirements of each request service to be allocated in the set, including the source node, destination node, capacity requirement, arrival time, maximum tolerable delay time and request duration; For each requested service to be allocated that arrives at the elastic optical network, based on its arrival time and the maximum tolerable delay time, the type of each requested service to be allocated is obtained; the type includes an immediate reservation request and an advance reservation request; Determine whether the destination node corresponding to the current request service to be allocated that arrives at the elastic optical network meets the computing resource requirements of the current request service to be allocated: If not, the establishment of the current requested service to be allocated fails; If it is satisfied, the K shortest paths algorithm is used to select K candidate paths from the source node to the destination node for the current request task to be assigned; all candidate paths are sorted in the order of the product of the number of spectrum slots required by each candidate path and the number of nodes on the candidate path from small to large to obtain a candidate path set; in the candidate path set, it is determined whether there is a candidate path that meets the spectrum consistency constraint, spectrum continuity constraint and time continuity constraint: If it exists, the first candidate path in the candidate path set that satisfies the spectrum consistency constraint, the spectrum continuity constraint, and the time continuity constraint is taken as the target working path; If not, based on the arrival time of the current request service to be allocated and the maximum tolerable delay time, determine whether the current request service to be allocated is an advance reservation request: If the current request service to be allocated is an immediate reservation request, the establishment of the current request service to be allocated fails; If the current request to be allocated is an advance reservation request, the current request to be allocated is placed in the reallocation request set; In the reallocation request set, based on the number of spectrum slots, duration and maximum tolerable delay time required by each request task to be allocated, a priority evaluation function of each request task to be allocated is constructed to obtain a priority function value of each request task to be allocated; According to the order of priority function values ​​from large to small, for each request task to be assigned in the reallocation request set, determine whether the waiting time of the request task to be assigned exceeds the maximum tolerable delay time corresponding to the request task to be assigned: If it exceeds, the establishment of the service to be allocated request fails; If it does not exceed, then within the maximum tolerable delay time of the request service to be allocated, a target working path is selected from the K cache candidate paths for the request service to be allocated; After obtaining the target working path of the current request service to be allocated, use the K shortest path algorithm to select K protection paths that do not intersect with the target working path for the current request service to be allocated, and select the protection path with the smallest product of the number of spectrum slots and the number of nodes on the path and satisfying the spectrum consistency constraint, spectrum continuity constraint and time continuity constraint as the dedicated protection path; Based on the target working path and the dedicated protection path of the current requested service to be allocated, a spectrum is allocated to the current requested service to be allocated, thereby completing the establishment of the current requested service to be allocated.

2. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 1, characterized in that: Elastic Optical Network , expressed as: ； in, represents a set of nodes in an elastic optical network; represents a set of fiber links; Represents the set of physical distances between adjacent nodes; It represents the set of available spectrum slots of the optical fiber link, expressed as , Indicates the elastic optical network The number of available spectrum slots in a fiber link, , Indicates the total number of fiber links in the elastic optical network; Represents the set of foreseeable time slots in the network, expressed as , Indicates The number of foreseeable time slots in the time-sensitive elastic optical network, , Indicates the number of moments in a resource allocation cycle.

3. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 1, characterized in that: Request business to be allocated , expressed as: ； in, Indicates the source node of the requested service to be allocated, Indicates the destination node of the requested service to be allocated; Indicates the capacity requirement of the requested service to be allocated, Indicates the arrival time of the requested service to be allocated, Indicates the maximum tolerable delay time of the requested service to be allocated; Indicates the requested duration of the requested service to be allocated, which is an integer multiple of the unit time slot.

4. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 1, characterized in that: Based on the arrival time of the current request service to be allocated and the maximum tolerable delay time, determining whether the current request service to be allocated is an advance reservation request includes: If the current request service is to be allocated Arrival time Equal to the actual start time of spectrum allocation , and the maximum tolerable delay time If it is 0, the current request service is to be allocated. For immediate reservation requests , expressed as: ； If the current request service is to be allocated Arrival time Less than the actual start time of spectrum allocation , or the maximum tolerable delay If it is greater than 0, the current request service is to be allocated. To reserve a request in advance , expressed as: 。 5. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 1, characterized in that: Based on the number of spectrum slots, duration and maximum tolerable delay time required by each request task to be assigned, a priority evaluation function for each request task to be assigned is constructed, including: Based on the modulation level, capacity requirement and bandwidth capacity of each request service to be allocated, the number of spectrum slots required for each request task to be allocated is obtained; Calculate the product of the modulation format and duration of the request task to be assigned as a resource requirement size measurement function of the request task to be assigned; Calculate the inverse of the maximum tolerable delay time of the request task to be assigned as a measurement function of the resource demand urgency of the request task to be assigned; The product of the resource requirement size measurement function and the resource requirement urgency measurement function of each request task to be assigned is calculated as the priority evaluation function of the request task to be assigned.

6. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 5, characterized in that: Based on the modulation level, capacity requirement and bandwidth capacity of each request service to be allocated, the number of spectrum slots required for each request task to be allocated is obtained, which is expressed as: ； in, represents the number of spectrum slots required for the requested task to be assigned, Indicates the capacity requirement of the requested service to be allocated; Indicates the modulation level determined according to the actual physical transmission distance of the requested service to be allocated; represents the basic bandwidth of the spectrum slot, Indicates the protection bandwidth.

7. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 6, characterized in that: The product of the modulation format and duration of the request task to be assigned is calculated as the resource requirement size measurement function of the request task to be assigned, which is expressed as: ； in, represents the resource requirement size measurement function, represents the number of spectrum slots required for the requested task to be assigned, Indicates duration.

8. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 7, characterized in that: The inverse of the maximum tolerable delay time of the request task to be assigned is calculated as the resource demand urgency measurement function of the request task to be assigned, which is expressed as: ； in, represents the resource demand urgency measurement function, Indicates the maximum tolerable delay time.

9. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 8, characterized in that: Calculate the product of the resource requirement size measurement function and the resource requirement urgency measurement function of each request task to be assigned as the priority evaluation function of the request task to be assigned, expressed as: 。 10. The method for allocating spectrum resources for service requests in an elastic optical network according to claim 1, characterized in that: After the service request to be allocated is completed, it also includes: releasing occupied resources, and updating spectrum resources and node computing resources of the optical fiber link in the elastic optical network.

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