CN106992810B - Shared protection route and spectrum allocation method considering joint fault probability constraint - Google Patents

Shared protection route and spectrum allocation method considering joint fault probability constraint Download PDF

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CN106992810B
CN106992810B CN201710050246.3A CN201710050246A CN106992810B CN 106992810 B CN106992810 B CN 106992810B CN 201710050246 A CN201710050246 A CN 201710050246A CN 106992810 B CN106992810 B CN 106992810B
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陈伯文
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/22—Alternate routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/03—Arrangements for fault recovery
    • H04B10/032—Arrangements for fault recovery using working and protection systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0079—Operation or maintenance aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation

Abstract

The invention relates to a shared protection route and spectrum allocation method and a system considering joint fault probability constraint, which are designed for reducing the fault risk of a service request in a spectrum flexible optical network.

Description

Shared protection route and spectrum allocation method considering joint fault probability constraint
Technical Field
The invention relates to the technical field of communication, in particular to a shared protection route and spectrum allocation method and system considering joint fault probability constraint.
Background
In the spectrum flexible optical network, on one hand, in order to improve the utilization rate of optical network resources, the bandwidth requirement of spectrum resource bearing service is fully utilized to ensure that the spectrum flexible optical network has the maximum throughput; on the other hand, in order to ensure the service quality in the service transmission process, each service request needs to be provided with a transmission working path and a backup protection path, so that the service interruption caused by the failure of the spectrum flexible optical network of the service request is reduced. Compared with the protection mode of the traditional Wavelength Division Multiplexing (WDM) optical network, the spectrally flexible optical network is more complex for service protection, because in the traditional WDM optical network, the bandwidth resource of the service request service is often a certain wavelength, while in the spectrally flexible optical network, the bandwidth occupied by the service request is a set of spectrum slots, and the allocation of the spectrum slots needs to obey two constraints of spectrum continuity and spectrum consistency. It can be seen that how to select a route of a service request and how to allocate spectrum resources on the selected route in a spectrum-flexible optical network become a key issue.
In order to make the service requests survivable, a working path and a link-disjoint protection path need to be established for each service request. In order to make full use of the spectrum resources of the optical network, the survivability of the service request is realized on the protection path by adopting a spectrum resource sharing mode. Currently, in a spectrum-agile optical network, in order to make a service request survivable, a dedicated protection and a shared protection mode are used for the service request to ensure the service quality of the service request. In particular, if shared protection is considered, two different approaches are generally adopted, which are described below:
(1) a conventional shared protection method. For each service request, a working path and a link disjoint protection path are calculated by using a shortest path algorithm, if the two working paths and the protection path are successfully established, then a first hit method is adopted to search and allocate spectrum resources on the established path, and the allocated spectrum resources must meet the constraint conditions of spectrum continuity and spectrum consistency. In particular, on the protection path, the spectrum is allocated by using the existing protection resources as much as possible, however, the spectrum resource sharing characteristic is not fully considered in this method.
(2) A service resource occupation disjoint sharing protection method. For each service request, 1) firstly, K working paths are calculated by using a K shortest path algorithm, then, spectrum resources are searched in the K paths by using a first hit method, a working path with available spectrum resources is selected, and bandwidth resources of the service request are reserved on the selected working path. 2) In order to ensure that the working path and the protection path have the characteristic of link disjointness, the working path selected by the service request is deleted, and then K protection paths are calculated by using a K shortest path algorithm. 3) In the K protection paths, if the number of reserved spectrum slots is different from the bandwidth requirement of the service request which needs to be established currently, all reserved protection spectrum resources are deleted, then corresponding shared protection spectrum resources are searched, and if the spectrum resources are found, the spectrum resources needed by the service request are reserved so as to fully utilize the established shared protection resources.
It can be seen that, in the spectrum flexible optical network, although the above two aspects solve the routing and spectrum allocation problem of the service request, the joint failure probability of the working path and the protection path of the transmission established by the service request is not evaluated.
In view of the above-mentioned defects, in order to better meet the bandwidth requirement of users, the invention actively makes research and innovation to create a method and a system for sharing protection routing and spectrum allocation considering joint failure probability constraint, so that the method and the system have industrial utilization value. In the process of establishing a service request, a working path and a protection path need to be established, and spectrum resources are allocated in the selected path, and in particular, spectrum slots allocated on the protection path can be shared, so as to ensure that the resource efficiency of the spectrum-agile optical network is maximized.
Disclosure of Invention
In order to solve the above problems of shared protection routing and spectrum allocation considering joint failure probability constraints, the present invention provides a method and a system for forming a primary optimization objective and a secondary optimization objective between spectrum resources and joint failure probabilities by setting different optimization objective adjustment parameters, so that the established service request can better enable network resources and service requests to have better survivability, achieve the balance of minimizing the joint failure probability between spectrum resource optimization and service requests, and form a shared protection routing and spectrum allocation considering joint failure probability constraints.
The invention relates to a shared protection route and spectrum allocation method considering joint fault probability constraint, which comprises the following steps:
generating a set of service requests TD, wherein each service request is associated with a TD (s, d, FS)s,d,MTFPs,d) e.TD represents, s and d represent the source node and destination node of the service request respectively, and s ≠ d, FSs,dRepresenting bandwidth requirements of service requests, MTFPs,dA maximum tolerable failure probability threshold representing a service request;
establishing a working path w and a shared protection path b of a service request, setting fault events of the working path w and the shared protection path b as mutually independent events, and taking the multiplication of the fault probability of the working path w and the fault probability of the shared protection path b as the joint fault probability of shared protection, wherein the formula is as follows:
Figure GDA0001990704880000031
wherein, the joint failure probability is less than or equal to the maximum tolerable failure probability threshold of the service request, and the formula is as follows:
Figure GDA0001990704880000032
setting the frequency spectrum resources and the joint fault probability of the frequency spectrum flexible optical network to be minimized into a multi-objective optimization function, wherein the multi-objective optimization function refers to: minimizing the occupied number of the frequency spectrum resources of the working path and the frequency spectrum resources of the shared protection path, minimizing the joint fault probability on the working path and the shared protection path into multi-objective joint optimization, and setting different optimization target adjusting parameters to form a primary optimization target and a secondary optimization target; wherein the constraint conditions to be satisfied by the multi-objective optimization function include: the method comprises the steps that a bandwidth flow conservation constraint condition, a frequency spectrum consistency constraint condition, a frequency spectrum continuity constraint condition, a working path and shared protection path pair selection uniqueness constraint condition, a frequency spectrum slot occupation uniqueness constraint condition, a frequency spectrum sharing constraint condition, a frequency spectrum slot maximum sharing degree constraint condition and a maximum tolerable fault probability threshold constraint condition of a service request are adopted; and obtaining the optimal solution of the multi-objective optimization function based on the constraint conditions which need to be met by the multi-objective optimization function, and completing the shared protection routing and the spectrum allocation considering the joint fault probability constraint.
Further, the method includes initializing a spectrum flexible optical network G (V, E, F), and setting topology information, an optical network connection state, a number of network switching nodes, a number of optical fiber links, a number of spectrum slots of each optical fiber link, and a failure probability of each optical fiber link of the spectrum flexible optical network, where V, E, F represents a set of all optical switching nodes, a set of all optical fiber links, and a set of all spectrum slots of each optical fiber link of the spectrum flexible optical network, respectively, that is, V ═ { V ═ V { (V, F)1,v2,…,vk,…,v|V|}、E＝{e1,e2,…,ek,…,e|E|}、F＝{1,2,…,fk,…,f|F|}; the | V |, | E |, and | F | respectively represent the number of optical switching nodes, the number of optical fiber links, and the number of spectrum slots of the spectrum flexible optical network; setting a failure probability for each fiber link of a spectrally flexible optical network, wherein ekThe probability of failure of a fiber link is
Figure GDA0001990704880000041
Further, the failure probability calculation formula on the working path is as follows:
Figure GDA0001990704880000042
wherein
Figure GDA0001990704880000043
Respectively showing the failure probability of the working path w and the working path w, eiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path; in the computational working path, the spectrum slot is not shared by other service requests;
the failure probability on the shared protection path is:
Figure GDA0001990704880000044
f, (b) and b respectively represent the fault probability of the shared protection path and the shared protection path selected by the service request;
in the calculation of the shared protection path, the reserved spectrum slots can be shared by different service requests, and a certain link e on the shared protection pathjIn the above, the maximum number of service requests sharing is set for each spectrum slot, and this number of service requests sharing is called the maximum spectrum sharing degree, and is represented by a symbol
Figure GDA0001990704880000045
Represents; the probability of successful recovery is
Figure GDA0001990704880000046
On a shared protection path, a certain link ejHas a survivable probability of the service request of
Figure GDA0001990704880000047
Wherein
Figure GDA0001990704880000048
For links e sharing protection pathsjThe probability of failure of (2).
Further, the multi-objective optimization function is specifically described as: in the spectrum flexible optical network G (V, E, F), a group of service requests TD is given, and | kappa | group of alternative working paths and shared protection paths between each node pair of the spectrum flexible optical network are configured in advance, and wb is useds，dIt is shown that,
Figure GDA0001990704880000049
wherein the kth group of working paths and the shared protection path are
Figure GDA00019907048800000410
Setting the optimization objective parameters α and setting the maximum degree of sharing for each spectral slot
Figure GDA00019907048800000411
The objective function minimizes the number of spectrum slots F occupied by a given set of traffic requests TD in all fiber links E of a spectrally flexible optical network G (V, E, F) and the joint probability of failure for selecting working paths and shared protection paths, as sub-table below:
Figure GDA00019907048800000412
wherein, the service request TD (s, d, FSs, d, MTFP) is represented by (s, d)s，d) The parameter α ∈ (0, 1) represents the weight for adjusting the primary and secondary optimization objectives;
Figure GDA0001990704880000052
and
Figure GDA0001990704880000053
representing a binary variable; w is as，dRepresenting the set of all working paths from source node s to destination node d, i.e.
Figure GDA0001990704880000054
Representing working paths in the kth set of path pairs from the source node s to the destination node d; e.g. of the typeiIs shown in the working pathThe ith optical fiber link in (1); e.g. of the typejRepresenting a jth fiber link in the spectrally flexible optical network; f belongs to F and represents a frequency spectrum slot with the number of F; k e k represents the kth set of path pairs, namely the kth set of working paths and protection paths, of any node pair;
Figure GDA0001990704880000056
representing the joint failure probability of the kth set of path pairs from source node s to destination node d.
Further, the primary optimization goal is to minimize the number of occupied spectrum resources of the working path and the shared protection path, and the secondary optimization goal is to minimize the joint failure probability on the working path and the shared protection path.
Further, the constraint conditions of the multi-objective optimization function specifically include:
(1) bandwidth flow conservation constraint conditions of service requests: each service request TD (s, d, FS) from the source node s to the destination node ds，d，MTFPs，d) In the working path
Figure GDA0001990704880000057
Any one optical fiber link e oniThe bandwidth flow through is equal to the service requestThe bandwidth requirement is formulated as:
service request TD (s, d, FS)s，d，MTFPs，d) In a shared protection path
Figure GDA0001990704880000059
Any optical fiber link e onjThe bandwidth traffic flowing through is also equal to the bandwidth requirement of this service request, and is formulated as:
wherein the content of the first and second substances,
Figure GDA00019907048800000511
is a known binary constant representing a service request TD (s, d, FS) from a source node s to a destination node ds，d，MTFPs，d) If passing through the working path
Figure GDA00019907048800000512
Over optical fibre link ei，Otherwise
Figure GDA00019907048800000514
Is a known binary constant representing a service request TD (s, d, FS) from a source node s to a destination node ds，d，MTFPs，d) If passing through the protection path
Figure GDA0001990704880000061
Over optical fibre link ej，Otherwise
Figure GDA0001990704880000063
FSs，dIndicating a service request TD (s, d, FS)s，d，MTFPs，d) The bandwidth requirement of (d);
(2) the constraint condition of the spectrum consistency is as follows: for each service request TD (s, d, FS)s，d，MTFPs，d) In the working path
Figure GDA0001990704880000064
Of any two different optical fiber links eiAnd enThe reserved spectrum slot numbers f must be identical, and are expressed by the following formula:
Figure GDA0001990704880000065
in a shared protection path
Figure GDA0001990704880000066
Of any two different optical fiber links ejAnd emThe reserved spectrum slot number f also ensures the consistency, and is expressed by the formula:
Figure GDA0001990704880000067
(3) the constraint condition of the continuity of the frequency spectrum: on the working path and the shared protection path, each service request TD (s, d, FS)s，d，MTFPs，d) The selected spectrum slot must satisfy the constraint condition of spectrum continuity when the binary variable is on the working path
Figure GDA0001990704880000068
And
Figure GDA0001990704880000069
when the spectrum slot with the number being larger than or equal to f +2 is not occupied by any other service request, the formula is as follows:
Figure GDA00019907048800000610
when binary variable
Figure GDA00019907048800000611
The spectrum slots with numbers less than f have been requested by a service TD (s, d, FS)s，d，MTFPs，d) Occupancy, formulated as:
Figure GDA00019907048800000612
also, on the shared protection path, binary variables
Figure GDA0001990704880000071
Binary variable of working path
Figure GDA0001990704880000072
The characteristics are the same;
when in useAndwhen the spectrum slot with the number being greater than or equal to f +2 is not occupied by any service request, the formula is shown as follows:
Figure GDA0001990704880000075
when in use
Figure GDA0001990704880000076
The spectrum slots numbered less than f have been requested by a service request TD (s, d, FS)s，d，MTFPs，d) Occupancy, formulated as:
wherein Θ represents an integer value greater than | F | × (| V | -1), where | V | -1 represents the maximum number of hops of a path between all pairs of nodes in the spectrally flexible optical network;
(4) the working path and shared protection path pair selects the uniqueness constraint condition: for each traffic request, among the κ sets of working path and shared protection path pairs, there is and only one set of working path and protection path pairs used to transmit the bandwidth resource of the traffic request, and this constraint is expressed by equation (14):
Figure GDA0001990704880000078
(5) the spectrum slots occupy a uniqueness constraint. At any one optical fiber link eiThe frequency spectrum slot numbered f can only be reserved as one service request TD (s, d, FS)s，d，MTFPs，d) The working spectrum resource or the shared protection spectrum resource is expressed by a formula as follows:
(6) spectrum sharing constraint conditions: optical fibre link e on a shared protection pathjIn the above, it is determined whether the spectrum slot with the number f is reserved as a group of shared spectrum resources requested by the service, which is expressed by the following two formulas:
Figure GDA00019907048800000710
Figure GDA0001990704880000081
(7) constraint condition of maximum sharing degree of frequency spectrum slot: optical fibre link e on a shared protection pathjThe spectral slot numbered f cannot be larger than
Figure GDA0001990704880000082
The service request is shared and is expressed by the formula:
Figure GDA0001990704880000083
(8) maximum tolerable failure probability threshold constraint: each service request TD (s, d, FS)s，d，MTFPs，d) The joint failure probability of the reserved working path and the protection path is smaller than or equal to the maximum tolerable failure probability threshold value of the service request, and the joint failure probability is expressed by a formula as follows:
Figure GDA0001990704880000084
the invention relates to a shared protection route and spectrum allocation system considering joint failure probability constraint, which comprises: the system comprises a service request generation module, a configuration module of a working path and a shared protection path, a joint failure probability calculation module of shared protection, a multi-objective optimization function module, a multi-objective optimization function constraint condition management module and an objective function optimization solution storage module;
the service request generating module is used for generating a group of service requests, including a source node, a destination node, a bandwidth requirement and a maximum tolerable fault probability threshold of the service requests; wherein each service request uses TD (s, d, FS)s，d，MTFPs，d) E TD represents, where s and d represent the source node and destination node of the service request, respectively, and s ≠ d, FSs，dRepresenting bandwidth requirements of service requests, MTFPs，dA maximum tolerable failure probability threshold representing a service request;
the configuration module of the working path and the shared protection path calculates the working path and the protection path group between any node pair by using a K shortest path algorithm to form a set of all path pairs from the source node s to the destination node d, namely forming a set of all path pairs
Figure GDA0001990704880000085
Wherein the kth group working path and the shared protection path of the node pair (s, d) are
Figure GDA0001990704880000086
Pre-configuring a working path and a shared protection path group between all node pairs of the spectrum flexible optical network;
the shared protection joint failure probability calculation module is used for calculating a joint failure probability set of all working paths and protection pairs from the source node s to the destination node d by using a shared protection joint failure probability calculation formula, namelyWherein
Figure GDA0001990704880000088
Representing the joint fault probability of the kth group of working paths and protection paths from the source node s to the destination node d, and pre-calculating the joint fault probability of the protection paths of the working paths of all the nodes of the spectrum flexible optical network;
the failure probability calculation formula on the working path is as follows:
Figure GDA0001990704880000091
the failure probability calculation formula on the shared protection path is as follows:
wherein
Figure GDA0001990704880000093
Respectively representing the failure probability values e of the working paths wiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path; in the computational working path, the spectrum slot is not shared by other service requests; f (b) and b represent the failure probability of the shared protection path and the shared protection path selected by the service request, respectively.
The multi-objective optimization function module is used for forming a group of multi-objective optimization functions with minimized spectrum resources occupied by service requests and minimized joint failure probability according to the set multiple optimization objectives, wherein the multi-objective optimization functions refer to: minimizing the occupied number of the frequency spectrum resources of the working path and the frequency spectrum resources of the shared protection path, minimizing the joint fault probability on the working path and the shared protection path into multi-objective joint optimization, and setting different optimization target adjusting parameters to form a primary optimization target and a secondary optimization target;
the multi-objective optimization function constraint condition management module is used for providing constraint conditions of the multi-objective optimization function, and comprises 8 different sub-modules:
(1) the service request bandwidth flow conservation constraint condition submodule is used for the principle that the service request bandwidth flow from a source node to a destination node is equal, namely the absolute value of the source node outflow flow and the absolute value of the destination node inflow flow are equal, and the difference of the intermediate node flow is 0;
(2) the spectrum consistency constraint condition submodule is used for reserving the same spectrum slot number on the working path or the shared protection path for each service request;
(3) the spectrum continuity constraint condition submodule is used for requiring that the spectrum slot selection of each service request must meet the continuous numbering requirement and cannot generate interval conditions;
(4) the working path and shared protection path pair selection uniqueness constraint condition submodule is used for selecting one or only one group of paths as the working path and the shared protection path of the service request in the K groups of working paths and shared protection path pairs for each service request;
(5) the spectrum slot occupation uniqueness constraint condition submodule is used for reserving each spectrum slot as a working spectrum resource of a service request or sharing a protection spectrum resource on any optical fiber link;
(6) the spectrum sharing constraint condition submodule is used for sharing each spectrum slot by a plurality of service requests on an optical fiber link of a shared protection path;
(7) sub-module of maximum sharing degree constraint condition of frequency spectrum slot for optical fiber link of shared protection pathejThe number of service requests shared by a certain frequency spectrum slot with the number f cannot be greater than the maximum sharing degree of the frequency spectrum slot;
(8) in the process of establishing a working path and shared protection by a service request, the joint failure probability of the selected working path and the shared protection path must be less than or equal to the maximum tolerable failure probability of the service request, otherwise, the working path and the shared protection path selected by the service request cannot meet the requirement of the existence of failure risk;
the objective function optimal solution storage module is used for setting a multi-objective optimization function adjusting parameter α according to the set optimization objective function and the known number of different service requests, operating the multi-objective optimization function module, obtaining the optimal solution of the multi-objective optimization function when all constraint conditions contained in the multi-objective optimization function constraint condition management module are met, and recording and storing the optimal solution.
The system further comprises a spectrum flexible optical network initialization module, which is used for setting topology information of the spectrum flexible optical network, optical network connection state, the number of network switching nodes, the number of optical fiber links, the number of spectrum slots of each optical fiber link, and the fault probability of each optical fiber link.
The system further comprises a network state monitoring module, which is used for effectively monitoring the spectrum flexible optical network parameter initialization, the service request generation, the maximum sharing degree of the spectrum resource setting, the joint fault probability calculation of the working path and the shared protection path, the multi-objective optimization function and the constraint condition of the multi-objective optimization function in real time.
Further, still include: and the optimization target evaluation module is used for evaluating and analyzing the obtained result according to the optimal solution obtained by the objective function, so that the frequency spectrum resource occupation of a given group of known service requests and the joint failure probability of shared protection are ensured to be minimized.
By the scheme, the shared protection routing and spectrum allocation method and system considering the joint fault probability constraint at least have the following advantages:
the invention establishes a shared protection path with a working path and a link which are not intersected for the service request, and evaluates the joint failure probability of the working path and the shared protection path, wherein the size of the joint failure probability of the shared protection must meet the maximum tolerable failure probability threshold of the service request, so that the failure risk of the service request in the transmission process is reduced, and the service quality of the service request in the transmission process is ensured. And on the selected shared protection path with the disjoint working path and the link, allocating the spectrum resource of the service request based on the bandwidth requirement of the service request, and solving the problems of routing and spectrum allocation of the service request. The method comprises the steps of minimizing the joint fault probability of spectrum resource occupation and sharing protection into a multi-objective optimization function, meeting bandwidth flow conservation constraint conditions, spectrum consistency constraint conditions, spectrum continuity constraint conditions, working path and sharing protection path pair selection uniqueness constraint conditions, spectrum slot occupation uniqueness constraint conditions, spectrum sharing constraint conditions, spectrum slot maximum sharing degree constraint conditions and maximum tolerable fault probability threshold constraint conditions of service requests, obtaining spectrum resource occupation and joint fault probability optimal solutions, solving the problem of sharing protection routing and spectrum allocation considering the joint fault probability constraint, improving the resource efficiency of the spectrum flexible optical network, reducing the fault probability of service request transmission, and ensuring the survivability of the service requests.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood and to be implemented according to the content of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
FIG. 1 is a flow chart of a shared protection routing and spectrum allocation method of the present invention that considers joint failure probability constraints;
FIG. 2 is a block diagram of a shared protection routing and spectrum allocation system of the present invention that considers joint failure probability constraints;
FIG. 3 illustrates a shared protection routing and spectrum allocation method considering joint failure probability constraints according to the present invention, in which the failure probability values of the optical fiber links of the spectrally flexible optical network are shown in specific examples;
fig. 4 is an optimal solution of the shared protection routing and spectrum allocation method considering joint failure probability constraint according to the present invention, in a specific example, the routing and spectrum allocation method of three service requests TD1(1,2,2,0.00073), TD2(1,2,2,0.00073), and TD3(1,2,2, 0.00073).
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The method comprises the steps of initializing a spectrum flexible optical network G (V, E, F) comprising topological information of the spectrum flexible optical network, optical network connection state, the number of network switching nodes, the number of optical fiber links, the number of spectrum slots of each optical fiber link and fault probability of each optical fiber link, generating a group of service requests comprising source nodes, destination nodes, bandwidth requirements and a maximum tolerable fault probability threshold value of the service requests, setting an adjustable parameter α and spectrum maximum sharing degree, selecting a uniqueness constraint condition, a spectrum slot occupation uniqueness constraint condition, a spectrum sharing constraint condition, a spectrum slot maximum sharing degree constraint condition and a spectrum distribution target function based on a sharing protection route and spectrum distribution target function of joint fault probability constraint, meeting bandwidth flow conservation constraint conditions, spectrum consistency constraint conditions, spectrum continuity constraint conditions, a working path and sharing protection path pair selection uniqueness constraint condition, a maximum tolerable fault probability constraint condition and spectrum slot maximum sharing constraint conditions of the service requests of a multi-objective optimization function, and obtaining spectrum resource occupation and joint fault probability optimal solution.
Example 1
As shown in fig. 1, the shared protection routing and spectrum allocation method considering joint failure probability constraint in the present embodiment includes:
initializing a spectrally flexible optical network G (V, E, F), wherein V, E, F denotes a set of all optical switching nodes, a set of all optical fiber links, a set of all spectral slots per optical fiber link of the spectrally flexible optical network, respectively, i.e. a set of all optical fiber linksV＝{v1，v2，...，vk，...，v|V|}、E＝{e1，e2，...，ek，...，e|E|}、F＝{1，2，...，fk，...f|F|}; the | V |, | E |, and | F | respectively represent the number of optical switching nodes, the number of optical fiber links, and the number of spectrum slots of the spectrum flexible optical network; setting a failure probability for each fiber link of a spectrally flexible optical network, wherein ekThe probability of failure of a fiber link is
Figure GDA0001990704880000121
Generating a set of service requests TD, wherein each service request is associated with a TD (s, d, FS)s，d，MTFPs，d) E TD, where s and d denote the source and destination nodes of the service request, respectively, and s ≠ d, FSs，dRepresenting bandwidth requirements of service requests, MTFPs，dRepresenting a maximum tolerable failure probability threshold for the service request.
In establishing the working path and the shared protection path, the joint failure probability of the working path and the shared protection path must satisfy the maximum tolerable failure probability threshold of the service request, that is, the joint failure probability of the working path and the shared protection path of the service request is less than or equal to the maximum tolerable failure probability threshold thereof.
1) In calculating the working path, since the spectrum slot is not shared by other service requests, the failure probability on the working path is calculated by the following formula:
wherein
Figure GDA0001990704880000123
Respectively showing the failure probability of the working path w and the working path w, eiAnd e w represents the failure probability of one optical fiber link and the optical fiber link on the working path.
2) In calculating shared protection paths, the reserved spectrum slot energyCan be shared by different service requests. In order to reduce service interruption due to multiple failures of service requests, a certain link e on the shared protection pathjIn the above, it is necessary to set the maximum number of shared service requests for each spectrum slot, and this number of shared service requests is called the maximum spectrum sharing degree, and is represented by a symbol
Figure GDA0001990704880000131
And (4) showing. When the spectrum flexible optical network fails, all service requests on a shared spectrum slot are likely to be lost, and only one of the service requests can be recovered, so the probability of successful recovery is
Figure GDA0001990704880000132
On a shared protection path, a certain link ejHas a survivable probability of the service request of
Figure GDA0001990704880000133
Wherein
Figure GDA0001990704880000134
For links e sharing protection pathsjProbability of failure. Thus, the probability of failure on a shared protection path is:
Figure GDA0001990704880000135
where f (b) and b represent the failure probability of the shared protection path and the shared protection path selected by the traffic request, respectively.
If the fault events of the working path w and the shared protection path b are considered to be mutually independent events, the fault probabilities of the working path w and the shared protection path b are in a multiplication form, and the joint fault probability of the shared protection is called as the joint fault probability of the shared protection. Thus, the joint failure probability of shared protection is:
Figure GDA0001990704880000136
since the service request must satisfy the maximum tolerable failure probability threshold in establishing the working path and the protection path, this constraint condition can be expressed by equation (4):
Figure GDA0001990704880000137
the method comprises the steps of setting an objective function of shared protection routing and spectrum allocation based on joint fault probability constraint, namely, minimizing the number of occupied spectrum resources and the joint fault probability of the spectrum flexible optical network into a multi-objective optimization function, wherein the objective function consists of a primary optimization objective and a secondary optimization objective, and different optimization objective proportions can be realized by adjusting the size of a parameter α.
In this embodiment, the multi-objective optimization function may be described as: in the spectrum flexible optical network G (V, E, F), a group of service requests TD is given, and | kappa | group of alternative working paths and protection paths between each node pair of the spectrum flexible optical network are configured in advance, and wb is useds，dIs shown, here
Figure GDA0001990704880000141
Wherein the kth group of working paths and the shared protection path are
Figure GDA0001990704880000142
Setting the optimization objective parameters α and setting the maximum degree of sharing for each spectral slot
Figure GDA0001990704880000143
The objective function minimizes the number of spectrum slots F occupied by a given set of traffic requests TD in all fiber links E of a spectrally flexible optical network G (V, E, F) and the joint probability of failure for selecting working and protection paths, which can be expressed by the following equation (5):
Figure GDA0001990704880000144
here, the service request TD (s, d, FS) is denoted by (s, d)s，d，MTFPs，d)；ws，dRepresenting a slave sourceSet of all working paths from node s to destination node d, i.e.
Figure GDA0001990704880000145
Representing working paths in the kth set of path pairs from the source node s to the destination node d; e.g. of the typeiIs shown in the working path
Figure GDA0001990704880000146
The ith optical fiber link in (1); e.g. of the typejRepresenting a jth fiber link in the spectrally flexible optical network; f belongs to F and represents a frequency spectrum slot with the number of F; k e k represents the kth set of path pairs, namely the kth set of working paths and protection paths, of any node pair;
Figure GDA0001990704880000147
representing the joint failure probability of the kth set of path pairs from source node s to destination node d.
In this embodiment, the main optimization objective is to minimize the occupied numbers of the spectrum resources of the working path and the spectrum resources of the shared protection path, that is, the first part and the second part of equation (5); the secondary optimization objective is to minimize the joint failure probability on the working path and the shared protection path, i.e. equation (5) third part.
The parameter α ∈ (0, 1) represents the weight to adjust the primary and secondary optimization objectives, Minimize represents the operation of minimizing spectrum slot occupancy and joint failure probability for a set of traffic requests in practical applications the weights of the primary and secondary optimization objectives may also be adjusted for different data by the parameter α ∈ (0, 1).
Figure GDA0001990704880000148
And
Figure GDA0001990704880000149
representing a binary variable; in one aspect, binary variables are utilized
Figure GDA00019907048800001410
Solving a set of given service requests TD on the working path
Figure GDA00019907048800001411
All links onOccupy a minimum number of spectral slots; on the other hand, using binary variables
Figure GDA00019907048800001413
Solving all optical fiber links e of a given set of service requests TD in a spectrally flexible optical networkjE, the number of occupied shared spectrum slots with the minimum value; finally, by means of binary variables
Figure GDA0001990704880000151
The minimum joint failure probability for a given set of traffic requests TD is solved.
The method has the advantages that the following constraint conditions are satisfied by a multi-objective optimization function which minimizes the occupied number of spectrum resources and the joint failure probability of the spectrum flexible optical network, and specifically comprises the following steps:
1) and bandwidth flow conservation constraint conditions of the service requests. On the one hand, each service request TD (s, d, FS) from the source node s to the destination node ds，d，MTFPs，d) In the working path
Figure GDA0001990704880000152
Any one optical fiber link e oniThe bandwidth traffic flowing through is equal to the bandwidth requirement of this service request and can be represented by equation (6). On the other hand, the service request TD (s, d, FS)s，d，MTFPs，d) In the protection path
Figure GDA0001990704880000153
Any optical fiber link e onjThe bandwidth traffic flowing through is also equal to the bandwidth requirement of this service request, and can be represented by equation (7).
Figure GDA0001990704880000154
Figure GDA0001990704880000155
Wherein the content of the first and second substances,
Figure GDA0001990704880000156
is a known binary constant representing a service request TD (s, d, FS) from a source node s to a destination node ds，d，MTFPs，d) If passing through the working pathOver optical fibre link ei，
Figure GDA0001990704880000158
Otherwise
Figure GDA0001990704880000159
Is a known binary constant representing a service request TD (s, d, FS) from a source node s to a destination node ds，d，MTFPs，d) If passing through the shared protection path
Figure GDA00019907048800001510
Over optical fibre link ej，
Figure GDA00019907048800001511
OtherwiseFSs，dIndicating a service request TD (s, d, FS)s，d，MTFPs，d) The bandwidth requirement of (c).
2) A spectral conformance constraint. For each service request TD (s, d, FS)s，d，MTFPs，d) In the working path
Figure GDA00019907048800001513
Of any two different optical fiber links eiAnd enThe numbers f of the reserved frequency spectrum slots are required to be consistent and the same and are represented by a formula (8); also in the warrantyProtect route
Figure GDA0001990704880000161
Of any two different optical fiber links ejAnd emThe reserved spectrum slot number f is also guaranteed to be the same and is represented by the formula (9).
Figure GDA0001990704880000163
3) A spectral continuity constraint. On the working path and the shared protection path, each service request TD (s, d, FS)s，d，MTFPs，d) The selected spectral slots must satisfy the spectral continuity constraint. On the working path, when the binary variable
Figure GDA0001990704880000164
And
Figure GDA0001990704880000165
when the frequency spectrum slot with the number being more than or equal to f +2 is not occupied by any other service request, namely, the frequency spectrum slot is expressed by the formula (10); when binary variableThe spectrum slots with numbers less than f have been requested by a service TD (s, d, FS)s，d，MTFPs，d) Occupancy is represented by formula (11). Also, on the shared protection path, binary variables
Figure GDA0001990704880000167
Binary variable of working path
Figure GDA0001990704880000168
The characteristics are the same. When in useAndwhen the frequency spectrum slot with the number being more than or equal to f +2 is not occupied by any service request, namely, the frequency spectrum slot is represented by a formula (12); when in use
Figure GDA00019907048800001611
The spectrum slots numbered less than f have been requested by a service request TD (s, d, FS)s，d，MTFPs，d) Occupancy is represented by formula (13).
Figure GDA00019907048800001612
Figure GDA00019907048800001613
Figure GDA00019907048800001614
Where Θ represents an integer value greater than | F | × (| V | -1), where | V | -1 represents the maximum number of hops of a path between all pairs of nodes in the spectrally flexible optical network.
4) The working path and shared protection path pair select a uniqueness constraint. For each traffic request, there is and only one set of working path and protection path pairs among the κ sets of working path and shared protection path pairs used to transmit the bandwidth resource of the traffic request, and this constraint may be represented by equation (14).
Figure GDA0001990704880000171
5) The spectrum slots occupy a uniqueness constraint. At any one optical fiber link eiThe frequency spectrum slot numbered f can only be reserved as one service request TD (s, d, FS)s，d，MTFPs，d) Or shared guard spectrum resources, described by equation (15):
Figure GDA0001990704880000172
6) spectrum sharing constraint conditions: optical fibre link e on a shared protection pathjIn the above, it is determined whether the spectrum slot with number f is reserved for the shared spectrum resource requested by a group of services, which is described by equations (16) and (17).
Figure GDA0001990704880000173
Figure GDA0001990704880000174
7) Constraint condition of maximum sharing degree of frequency spectrum slot: optical fibre link e on a shared protection pathjThe spectral slot numbered f cannot be larger than
Figure GDA0001990704880000175
The service requests are shared.
8) Maximum tolerable failure probability threshold constraint: each service request TD (s, d, FS)s，d，MTFPs，d) The joint failure probability of the reserved working path and the protection path is less than or equal to the maximum tolerable failure probability threshold of the service request, which is expressed by the following equation (19):
Figure GDA0001990704880000177
example 2
As shown in fig. 2, the present embodiment considers a shared protection route and spectrum allocation system with joint failure probability constraint, which includes: the system comprises a service request generation module, a configuration module of a working path and a shared protection path, a joint failure probability calculation module of shared protection, a multi-objective optimization function module, a multi-objective optimization function constraint condition management module and an objective function optimization solution storage module;
the service request generating module is used for generating a group of service requests, including a source node, a destination node, a bandwidth requirement and a maximum tolerable fault probability threshold of the service requests; wherein each service request uses TD (s, d, FS)s，d，MTFPs，d) E TD represents, where s and d represent the source node and destination node of the service request, respectively, and s ≠ d, FSs，dRepresenting bandwidth requirements of service requests, MTFPs，dA maximum tolerable failure probability threshold representing a service request;
the configuration module of the working path and the shared protection path is used for calculating the working path and the protection path group between any node pair through a K shortest path algorithm to form a set of all path pairs from the source node s to the destination node d, namely forming a set of all path pairs
Figure GDA0001990704880000181
Wherein the kth group working path and the shared protection path of the node pair (s, d) are
Figure GDA0001990704880000182
Pre-configuring a working path and a shared protection path group between all node pairs of the spectrum flexible optical network;
the shared protection joint failure probability calculation module is used for calculating a joint failure probability set of all working paths and protection pairs from the source node s to the destination node d by using a shared protection joint failure probability calculation formula, namely
Figure GDA0001990704880000183
Wherein
Figure GDA0001990704880000184
Representing the joint failure probability of the kth group of working paths and protection paths from the source node s to the destination node d, and connecting the spectrum flexible optical networkThe joint failure probability of the protection path of the working path with the node is calculated in advance;
the failure probability calculation formula on the working path is as follows:
Figure GDA0001990704880000185
the failure probability calculation formula on the shared protection path is as follows:
Figure GDA0001990704880000186
wherein the content of the first and second substances,
Figure GDA0001990704880000187
respectively representing the failure probability values e of the working path w and the working path wiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path; in the computational working path, the spectrum slot is not shared by other service requests; f, (b) and b respectively represent the failure probability of the shared protection path and the shared protection path selected by the service request;
the multi-objective optimization function module is used for requesting TD (s, d, FS) according to a known group of services，d，MPs，d) And configuration information of the spectrum flexible optical network G (V, E, F), setting the frequency spectrum resources occupied by all service requests in the spectrum flexible optical network to be minimized as a main optimization target, and forming a group of multi-target optimization functions for minimizing the frequency spectrum resources occupied by the service requests and the joint fault probability according to the set multi-optimization targets, wherein the multi-optimization targets refer to: minimizing the occupied number of the spectrum resources of the working path and the spectrum resources of the shared protection path, minimizing the joint fault probability on the working path and the shared protection path to form a multi-objective joint optimization target, and setting different optimization target adjusting parameters to form a primary optimization target and a secondary optimization target;
the multi-objective optimization function constraint condition management module is used for providing constraint conditions of the multi-objective optimization function, and comprises 8 different sub-modules:
(1) the bandwidth flow conservation constraint condition submodule of the service request is used for the principle that the bandwidth flow of the service request from a source node to a destination node is equal, namely the absolute value of the outflow flow of the source node is equal to the absolute value of the inflow flow of the destination node, and the difference of the flows of the intermediate nodes is 0 because the inflow attribute and the outflow attribute exist when the service flow passes through the intermediate nodes and the flows are the same;
(2) the spectrum consistency constraint condition submodule is used for reserving the same spectrum slot number on the working path or the shared protection path for each service request;
(3) the spectrum continuity constraint condition submodule is used for requiring that the spectrum slot selection of each service request must meet the continuous numbering requirement and cannot generate interval conditions;
(4) the working path and shared protection path pair selection uniqueness constraint condition submodule is used for selecting one or only one group of paths as the working path and the shared protection path of the service request in the K groups of working paths and shared protection path pairs for each service request;
(5) the spectrum slot occupation uniqueness constraint condition submodule is used for reserving each spectrum slot as a working spectrum resource of a service request or sharing a protection spectrum resource on any optical fiber link;
(6) the spectrum sharing constraint condition submodule is used for sharing each spectrum slot by a plurality of service requests on an optical fiber link of a shared protection path;
(7) a sub-module of the maximum sharing degree constraint condition of the frequency spectrum slot for an optical fiber link e of the shared protection pathjThe number of service requests shared by a certain frequency spectrum slot with the number f cannot be greater than the maximum sharing degree of the frequency spectrum slot;
(8) in the process of establishing a working path and sharing protection by a user service request, the joint failure probability of the selected working path and the sharing protection path must be less than or equal to the maximum tolerable failure probability of the service request, otherwise, the working path and the sharing protection path selected by the service request cannot meet the requirement of the existence of failure risk;
the objective function optimal solution storage module is used for setting a multi-objective optimization function adjusting parameter α according to the set optimization objective function and the known number of different service requests, operating the multi-objective optimization function module, obtaining the optimal solution of the multi-objective optimization function when all constraint conditions contained in the multi-objective optimization function constraint condition management module are met, and recording and storing the optimal solution.
And the network state monitoring module is used for finishing the real-time effective monitoring of the initialization of the spectrum flexible optical network parameters, the generation of the service request, the setting of the maximum sharing degree of the spectrum resources, the joint fault probability calculation of the working path and the shared protection path, the multi-objective optimization function and the constraint conditions of the multi-objective optimization function so as to realize the optimized spectrum resource occupation and joint fault probability of the service request in the spectrum flexible optical network.
And the objective function optimization solution storage module is used for acquiring an optimal solution of the multi-objective optimization function according to the set optimization objective function, knowing the number of different service requests, operating the optimization objective function with the minimum spectrum resource and joint fault probability, meeting all constraint conditions contained in the objective function, and recording and storing the optimal solution. The method is used for obtaining the optimal solution of the multi-objective optimization function according to the set optimization objective function, knowing the number of different service requests, operating the optimization objective function set by the multi-objective optimization function module, meeting all constraint conditions contained in the multi-objective optimization function constraint condition management module, and recording and storing the optimal solution.
And the optimization target evaluation module is used for evaluating and analyzing the obtained result according to the optimal solution obtained by the objective function, ensuring that the spectrum resource occupation of a given group of known service requests and the joint failure probability of the shared protection are minimized, and finishing the routing and spectrum allocation of the beam shared protection based on the joint failure probability constraint.
In the system description, the goals of the optimal route and the frequency spectrum allocation of the shared protection based on the joint fault probability constraint are completed through the mutual cooperation of different modules, and the minimum joint fault probability of the working path selected by the service request and the shared protection path is realized at the same time.
The invention relates to a method and a system for sharing protection routing and spectrum allocation considering joint failure probability constraint, wherein the specific examples are further described as follows:
first, fig. 3 shows a spectrum flexible optical network, each optical fiber link is bidirectional, the numerical value on the optical fiber link represents the failure probability of each link, the spectrum bandwidth of each optical fiber link is set to 200GHz, and if each spectrum slot is 12.5GHz, the optical fiber links have 16 spectrum slots in total.
Second, a set of service requests TD1(1,2,2,0.00073), TD2(1,2,2,0.00073), TD3(1,2,2,0.00073) is generated.
Third, adjustable parameter α is set to 0.5 and the spectrum maximum shareThe method comprises the steps of minimizing the number of occupied spectrum resources and the joint failure probability of the spectrum flexible optical network into a multi-objective optimization function (formula (5)), meeting bandwidth and flow conservation constraint conditions of service requests of the multi-objective optimization function (formula (6) and formula (7)), spectrum consistency constraint conditions (formula (8) and formula (9)), spectrum continuity constraint conditions (formula (10) to formula (13)), a working path and shared protection path pair selection uniqueness constraint condition (formula (14)), a spectrum slot occupation uniqueness constraint condition (formula (15)), a spectrum sharing constraint condition (formula (16) and formula (17)), a spectrum slot maximum sharing degree constraint condition (formula (18)), and a maximum tolerable failure probability threshold constraint condition (formula (19)).
And finally, obtaining the target function optimization of the shared protection route and the frequency spectrum distribution based on the joint fault probability constraint: 9.001035, that is, as shown in fig. 4, the working paths selected by the service requests TD1(1,2,2,0.00073), TD2(1,2,2,0.00073) and TD3(1,2,2,0.00073) are: 1-2, the allocated spectrum slots are numbered 0 and 1,2 and 3, 4 and 5; on the selected shared protection path 1-0-3-2, the service requests TD1(1,2,2,0.00073) and TD2(1,2,2,0.00073) are allocated spectrum slots numbered both 0 and 1, and since the set maximum sharing degree is 2, the service requests TD3(1,2,2,0.00073) cannot share the spectrum slots numbered 0 and 1 occupied by TD1(1,2,2,0.00073) and TD2(1,2,2,0.00073), and can only be allocated spectrum slots numbered 2 and 3. Using equation (4), the joint failure probability of the working path and the shared protection path selected by the service request TD1(1,2,2,0.00073) is 0.00069, which is smaller than the maximum tolerable failure probability threshold 0.00073 of the service request, and then the working path (1-2) and the shared protection path 1-0-3-2 established by the service request satisfy the constraint condition of the maximum tolerable failure probability threshold. Likewise, using equation (4), the working path (1-2) and the shared protection path 1-0-3-2 selected by the traffic request TD2(1,2,2,0.00073), TD3(1,2,2,0.00073) also satisfy the constraint of the maximum tolerable failure probability threshold (0.00073).
The embodiment of the method may be implemented by the embodiment of the system, and the embodiment of the system may adopt the real-time operation of the method.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (8)

1. A method for shared protection routing and spectrum allocation that considers joint failure probability constraints, comprising:
initializing a spectrum flexible optical network G (V, E, F), and setting topology information, optical network connection state and network intersection of the spectrum flexible optical networkThe number of switching nodes, the number of optical fiber links, the number of spectrum slots of each optical fiber link, and the failure probability of each optical fiber link, where V, E, F represents all optical switching node sets, all optical fiber link sets, and all spectrum slot sets of each optical fiber link of the spectrum flexible optical network, respectively, and V ═ { V ═ V { (V { [ V ])1,v2,…,vk,…,v|V|}、E＝{e1,e2,…,ek,…,e|E|}、F＝{1,2,…,fk,…,f|F|}; the | V |, | E |, and | F | respectively represent the number of optical switching nodes, the number of optical fiber links, and the number of spectrum slots of the spectrum flexible optical network; setting a failure probability for each fiber link of a spectrally flexible optical network, wherein ekThe probability of failure of a fiber link is
Figure FDA0002302529480000011
Generating a set of service requests TD, wherein each service request is associated with a TD (s, d, FS)s,d,MTFPs,d) e.TD represents, s and d represent the source node and destination node of the service request respectively, and s ≠ d, FSs,dRepresenting bandwidth requirements of service requests, MTFPs,dA maximum tolerable failure probability threshold representing a service request;
establishing a working path w and a shared protection path b of a service request, setting fault events of the working path w and the shared protection path b as mutually independent events, and taking the multiplication of the fault probability of the working path w and the fault probability of the shared protection path b as the joint fault probability of shared protection, wherein the formula is as follows:
wherein, w, ei、
Figure FDA0002302529480000014
Respectively showing the working paths w, eiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path;
b represents a shared protection path;
ejrepresenting a link on a shared protection path;
Figure FDA0002302529480000015
the number of the shared service requests is called as the maximum spectrum sharing degree;
Figure FDA0002302529480000016
for links e sharing protection pathsjThe probability of failure;
wherein, the joint failure probability is less than or equal to the maximum tolerable failure probability threshold of the service request, and the formula is as follows:
Figure FDA0002302529480000013
setting the frequency spectrum resources and the joint fault probability of the frequency spectrum flexible optical network to be minimized into a multi-objective optimization function, wherein the multi-objective optimization function refers to: minimizing the occupied number of the frequency spectrum resources of the working path and the frequency spectrum resources of the shared protection path, minimizing the joint fault probability on the working path and the shared protection path into multi-objective joint optimization, and setting different optimization target adjusting parameters to form a primary optimization target and a secondary optimization target; wherein the constraint conditions to be satisfied by the multi-objective optimization function include: the method comprises the steps that a bandwidth flow conservation constraint condition, a frequency spectrum consistency constraint condition, a frequency spectrum continuity constraint condition, a working path and shared protection path pair selection uniqueness constraint condition, a frequency spectrum slot occupation uniqueness constraint condition, a frequency spectrum sharing constraint condition, a frequency spectrum slot maximum sharing degree constraint condition and a maximum tolerable fault probability threshold constraint condition of a service request are adopted;
and obtaining the optimal solution of the multi-objective optimization function based on the constraint conditions which need to be met by the multi-objective optimization function, and completing the shared protection routing and the spectrum allocation considering the joint fault probability constraint.
2. The method for shared protection routing and spectrum allocation considering joint failure probability constraints according to claim 1, wherein the failure probability on working paths is calculated by the following formula:
Figure FDA0002302529480000021
wherein w, F (w), ei、
Figure FDA0002302529480000023
Respectively showing the failure probability of the working path w and the working path w, eiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path; in the computational working path, the spectrum slot is not shared by other service requests;
the failure probability on the shared protection path is:
Figure FDA0002302529480000022
f, (b) and b respectively represent the fault probability of the shared protection path and the shared protection path selected by the service request;
in the calculation of the shared protection path, the reserved spectrum slots can be shared by different service requests, and a certain link e on the shared protection pathjIn the above, the maximum number of service requests sharing is set for each spectrum slot, and this number of service requests sharing is called the maximum spectrum sharing degree, and is represented by a symbol
Figure FDA0002302529480000024
Represents; the probability of successful recovery is
Figure FDA0002302529480000025
On a shared protection path, a certain link ejHas a survivable probability of the service request ofWherein
Figure FDA0002302529480000027
For links e sharing protection pathsjThe probability of failure of (2).
3. The method for shared protection routing and spectrum allocation considering joint failure probability constraints as claimed in claim 1, wherein the multi-objective optimization function is specifically described as: in the spectrum flexible optical network G (V, E, F), a group of service requests TD is given, and | kappa | group of alternative working paths and shared protection paths between each node pair of the spectrum flexible optical network are configured in advance, and wb is useds，dIt is shown that,
Figure FDA0002302529480000032
wherein the kth group of working paths and the shared protection path are
Figure FDA0002302529480000033
Setting the optimization objective parameters α and setting the maximum degree of sharing for each spectral slot
Figure FDA0002302529480000034
The multi-objective optimization function minimizes the number of spectrum slots F occupied by a given set of traffic requests TD in all optical fiber links E of the spectrally flexible optical network G (V, E, F) and the joint probability of failure for selecting working paths and shared protection paths, as sub-represented by:
Figure FDA0002302529480000031
wherein, the service request TD (s, d, FS) is represented by (s, d)s,d,MTFPs,d) The parameter α ∈ (0, 1) represents the weight for adjusting the primary and secondary optimization objectives;and
Figure FDA0002302529480000036
representing a binary variable; w is as，dRepresenting the set of all working paths from source node s to destination node d,
Figure FDA0002302529480000038
representing working paths in the kth set of path pairs from the source node s to the destination node d; e.g. of the typeiIs shown in the working path
Figure FDA00023025294800000311
The ith optical fiber link in (1); e.g. of the typejRepresenting a jth fiber link in the spectrally flexible optical network; f belongs to F and represents a frequency spectrum slot with the number of F; k belongs to k and represents the kth group of path pairs, the kth group of working paths and the shared protection paths of any node pair;
Figure FDA0002302529480000039
representing the joint failure probability of the kth set of path pairs from source node s to destination node d.
4. The method of claim 3, wherein the primary optimization objective is minimization of the number of spectrum resources of the working path and the spectrum resources of the shared protection path, and the secondary optimization objective is minimization of the joint failure probability on the working path and the shared protection path.
5. The method for shared protection routing and spectrum allocation considering joint failure probability constraints according to claim 1, wherein the constraint conditions of the multi-objective optimization function specifically include:
(1) bandwidth flow conservation constraint conditions of service requests: each service request TD(s) from the source node s to the destination node d,d,FSs,d,MTFPs,d) In the working path
Figure FDA00023025294800000310
Any one optical fiber link e oniThe bandwidth traffic flowing through is equal to the bandwidth requirement of the service request, and is formulated as:
Figure FDA0002302529480000041
service request TD (s, d, FS)s,d,MTFPs,d) In a shared protection pathAny optical fiber link e onjThe bandwidth traffic flowing through is also equal to the bandwidth requirement of this service request, and is formulated as:
Figure FDA0002302529480000042
wherein the content of the first and second substances,
Figure FDA0002302529480000046
is a known binary constant representing a service request TD (s, d, FS) from a source node s to a destination node ds,d,MTFPs,d) If passing through the working pathOver optical fibre link ei，
Figure FDA00023025294800000414
Otherwise
Figure FDA0002302529480000047
Figure FDA0002302529480000048
Is a known binary constant that represents the slave sourceService request TD (s, d, FS) from node s to destination node ds,d,MTFPs,d) If passing through the shared protection path
Figure FDA00023025294800000415
Over optical fibre link ej，
Figure FDA00023025294800000410
OtherwiseFSs,dIndicating a service request TD (s, d, FS)s,d,MTFPs,d) The bandwidth requirement of (d);
(2) the constraint condition of the spectrum consistency is as follows: for each service request TD (s, d, FS)s,d,MTFPs,d) In the working path
Figure FDA00023025294800000411
Of any two different optical fiber links eiAnd enThe reserved spectrum slot numbers f must be identical, and are expressed by the following formula:
Figure FDA0002302529480000043
in a shared protection path
Figure FDA00023025294800000412
Of any two different optical fiber links ejAnd emThe reserved spectrum slot number f also ensures the consistency, and is expressed by the formula:
Figure FDA0002302529480000044
(3) the constraint condition of the continuity of the frequency spectrum: on the working path and the shared protection path, each service request TD (s, d, FS)s,d,MTFPs,d) The selected spectrum slot must satisfy the constraint condition of spectrum continuity and workOn the path, when the binary variable
Figure FDA0002302529480000055
And
Figure FDA0002302529480000056
when the spectrum slot with the number being larger than or equal to f +2 is not occupied by any other service request, the formula is as follows:
Figure FDA0002302529480000051
when binary variable
Figure FDA0002302529480000057
The spectrum slots with numbers less than f have been requested by a service TD (s, d, FS)s,d,MTFPs,d) Occupancy, formulated as:
Figure FDA0002302529480000052
also, on the shared protection path, binary variables
Figure FDA00023025294800000511
Binary variable of working path
Figure FDA00023025294800000512
The characteristics are the same;
when in use
Figure FDA0002302529480000058
Andwhen the spectrum slot with the number being larger than or equal to f +2 is not occupied by any service request, the formula is as follows:
Figure FDA0002302529480000053
when in use
Figure FDA00023025294800000510
The spectrum slots numbered less than f have been requested by a service request TD (s, d, FS)s,d,MTFPs,d) Occupancy, formulated as:
wherein Θ represents an integer value greater than | F | × (| V | -1), where | V | -1 represents the maximum number of hops of a path between all pairs of nodes in the spectrally flexible optical network;
(4) the working path and shared protection path pair selects the uniqueness constraint condition: for each service request, among the κ sets of working path and shared protection path pairs, there is and only one set of working path and shared protection path pair used to transmit the bandwidth resource of the service request, and this constraint is expressed by equation (14):
Figure FDA0002302529480000061
(5) the spectrum slots occupy a uniqueness constraint. At any one optical fiber link eiThe frequency spectrum slot numbered f can only be reserved as one service request TD (s, d, FS)s,d,MTFPs,d) The working spectrum resource or the shared protection spectrum resource is expressed by a formula as follows:
Figure FDA0002302529480000062
(6) spectrum sharing constraint conditions: optical fibre link e on a shared protection pathjIn the above, it is determined whether the spectrum slot with the number f is reserved as a group of shared spectrum resources requested by the service, which is expressed by the following two formulas:
Figure FDA0002302529480000063
Figure FDA0002302529480000064
(7) constraint condition of maximum sharing degree of frequency spectrum slot: optical fibre link e on a shared protection pathjThe spectral slot numbered f cannot be larger than
Figure FDA0002302529480000067
The service request is shared and is expressed by the formula:
Figure FDA0002302529480000065
(8) maximum tolerable failure probability threshold constraint: each service request TD (s, d, FS)s,d,MTFPs,d) The joint failure probability of the reserved working path and the shared protection path is smaller than or equal to the maximum tolerable failure probability threshold value of the service request, and the joint failure probability is expressed by a formula as follows:
Figure FDA0002302529480000066
6. a shared protection routing and spectrum allocation system that considers joint failure probability constraints, comprising: the system comprises a spectrum flexible optical network initialization module, a service request generation module, a working path and shared protection path configuration module, a shared protection joint fault probability calculation module, a multi-objective optimization function constraint condition management module and an objective function optimization solution storage module;
the spectrum flexible optical network initialization module is used for setting topology information of the spectrum flexible optical network, an optical network connection state, the number of network switching nodes, the number of optical fiber links, the number of spectrum slots of each optical fiber link and the fault probability of each optical fiber link;
the service request generating module is used for generating a group of service requests, including a source node, a destination node, a bandwidth requirement and a maximum tolerable fault probability threshold of the service requests; wherein each service request uses TD (s, d, FS)s,d,MTFPs,d) E TD represents, where s and d represent the source node and destination node of the service request, respectively, and s ≠ d, FSs,dRepresenting bandwidth requirements of service requests, MTFPs,dA maximum tolerable failure probability threshold representing a service request;
the configuration module of the working path and the shared protection path is used for calculating the working path and the shared protection path group between any node pair by using a K shortest path algorithm to form a set of all path pairs from the source node s to the destination node d to form a set of all path pairs
Figure FDA0002302529480000073
Wherein the kth group working path and the shared protection path of the node pair (s, d) are
Figure FDA0002302529480000074
Pre-configuring a working path and a shared protection path group between all node pairs of the spectrum flexible optical network;
the joint failure probability calculation module of the shared protection is used for calculating the joint failure probability set of all working paths and protection pairs from the source node s to the destination node d by utilizing a joint failure probability calculation formula of the shared protection,
Figure FDA0002302529480000076
wherein
Figure FDA0002302529480000075
Representing the joint fault probability of the kth group of working paths and shared protection paths from the source node s to the destination node d, and pre-calculating the joint fault probability of the working paths and the shared protection paths of all the nodes of the spectrum flexible optical network;
the failure probability calculation formula on the working path is as follows:
Figure FDA0002302529480000071
the failure probability calculation formula on the shared protection path is as follows:
Figure FDA0002302529480000072
wherein w, F (w), ei、
Figure FDA0002302529480000077
Respectively showing the failure probability of the working path w and the working path w, eiE w represents the failure probability of one optical fiber link and the optical fiber link on the working path; in the computational working path, the spectrum slot is not shared by other service requests; f, (b) and b respectively represent the failure probability of the shared protection path and the shared protection path selected by the service request;
the multi-objective optimization function module is used for forming a group of multi-objective optimization functions with minimized spectrum resources occupied by service requests and minimized joint failure probability according to the set multiple optimization objectives, wherein the multi-objective optimization functions refer to: minimizing the occupied number of the frequency spectrum resources of the working path and the frequency spectrum resources of the shared protection path, minimizing the joint fault probability on the working path and the shared protection path into multi-objective joint optimization, and setting different optimization target adjusting parameters to form a primary optimization target and a secondary optimization target;
the multi-objective optimization function constraint condition management module is used for providing constraint conditions of the multi-objective optimization function, and comprises 8 different sub-modules:
(1) the service request bandwidth flow conservation constraint condition submodule is used for the principle that the service request bandwidth flow from a source node to a destination node is equal, the absolute value of the source node outflow flow and the absolute value of the destination node inflow flow are equal, and the difference of the intermediate node flow is 0;
(2) the spectrum consistency constraint condition submodule is used for numbering the reserved spectrum slots on the working path or the shared protection path according to each service request, and the spectrum consistency constraint condition submodule is used for numbering the spectrum slots on the working path or the shared protection path according to the requirement;
(3) the spectrum continuity constraint condition submodule is used for requiring that the spectrum slot selection of each service request must meet the continuous numbering requirement and cannot generate interval conditions;
(4) the working path and shared protection path pair selection uniqueness constraint condition submodule is used for selecting one or only one group of paths as the working path and the shared protection path of the service request in the K groups of working paths and shared protection path pairs for each service request;
(5) the spectrum slot occupation uniqueness constraint condition submodule is used for reserving each spectrum slot as a working spectrum resource of a service request or sharing a protection spectrum resource on any optical fiber link;
(6) the spectrum sharing constraint condition submodule is used for sharing each spectrum slot by a plurality of service requests on an optical fiber link of a shared protection path;
(7) a sub-module of the maximum sharing degree constraint condition of the frequency spectrum slot for an optical fiber link e of the shared protection pathjThe number of service requests shared by a certain frequency spectrum slot with the number f cannot be greater than the maximum sharing degree of the frequency spectrum slot;
(8) the maximum tolerable failure probability threshold value constraint condition submodule is used for ensuring that the joint failure probability of the selected working path and the shared protection path is less than or equal to the maximum tolerable failure probability of the service request in the process of establishing the working path and the shared protection path by the user service request, otherwise, the working path and the shared protection path selected by the service request cannot meet the requirement of the existence of failure risk;
the objective function optimal solution storage module is used for setting a multi-objective optimization function adjusting parameter α according to the set optimization objective function and the known number of different service requests, operating the multi-objective optimization function module, obtaining the optimal solution of the multi-objective optimization function when all constraint conditions contained in the multi-objective optimization function constraint condition management module are met, and recording and storing the optimal solution.
7. The shared protection routing and spectrum allocation system according to claim 6, further comprising a network status monitoring module for performing real-time effective monitoring on the spectrum-agile optical network parameter initialization, the service request generation, the maximum sharing degree of the spectrum resource setting, the joint failure probability calculation of the working path and the shared protection path, the multi-objective optimization function, and the constraint condition of the multi-objective optimization function.
8. The shared protection routing and spectrum allocation system that considers joint failure probability constraints according to claim 6, further comprising: and the optimization target evaluation module is used for evaluating and analyzing the obtained result according to the optimal solution obtained by the objective function, so that the frequency spectrum resource occupation of a given group of known service requests and the joint failure probability of shared protection are ensured to be minimized.
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