CN114302267A - Special protection spectrum allocation method and system for space division multiplexing optical network of data center - Google Patents
Special protection spectrum allocation method and system for space division multiplexing optical network of data center Download PDFInfo
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- CN114302267A CN114302267A CN202111527574.0A CN202111527574A CN114302267A CN 114302267 A CN114302267 A CN 114302267A CN 202111527574 A CN202111527574 A CN 202111527574A CN 114302267 A CN114302267 A CN 114302267A
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Abstract
The invention relates to a special protection spectrum allocation method and a special protection spectrum allocation system for a space division multiplexing optical network of a data center, wherein the method comprises the steps of firstly establishing a working path and a special protection path for each connection request, secondly, calculating the free spectrum availability values of all fiber cores according to the spectrum use conditions on each optical fiber link, and sequentially selecting the fiber cores according to descending order; then, under the constraints of spectrum continuity and consistency, selecting an available spectrum block and calculating a crosstalk value of the spectrum block on each link; and then, judging whether the crosstalk value on each link meets the limit of a crosstalk threshold value, if so, reserving the frequency spectrum block, and performing frequency spectrum allocation, so that the problems of routing calculation, fiber core selection and frequency spectrum allocation based on crosstalk sensing are solved, the frequency spectrum resource efficiency of the space division multiplexing optical network is improved, the cross crosstalk value of each optical fiber link is reduced, and the frequency spectrum resources and the cross crosstalk occupied by the working path and the special protection path established by each connection request are optimized.
Description
Technical Field
The present invention relates to the field of communications network technologies, and in particular, to a method and a system for allocating a protection spectrum dedicated to a spatial division multiplexing optical network in a data center.
Background
Because the bandwidth requirement provided by the traditional wavelength division multiplexing optical network cannot meet the requirement of rapid increase of the bandwidth of the optical network in recent years, and the high-efficiency resource efficiency of the network cannot be ensured, the elastic optical network can flexibly cut and allocate the frequency spectrum resources of the network according to the service requirement, thereby avoiding the frequency spectrum waste and improving the utilization rate of the frequency spectrum resources. Therefore, elastic optical networks have become a hot spot of research.
In order to solve the problem, the traditional elastic optical network based on the single-mode single-core optical fiber faces the challenge of reaching the physical capacity limit, and the space division multiplexing technology represented by the multi-core optical fiber changes the original single-core optical fiber into the multi-core optical fiber, so that the capacity of the optical fiber can be theoretically expanded to the multiple of the number of the cores, and the transmission capacity of the optical fiber is greatly improved. However, in the multi-core fiber, when an optical signal is transmitted between different cores, power leakage occurs to cause a crosstalk problem between the different cores, which affects the end-to-end optical signal transmission quality, thereby limiting the transmission range and deployment scale of the multi-core fiber. Particularly, when the service in the multi-fiber core elastic optical network allocates the spectrum resources of the network, if the spectrum gaps with the same number in the adjacent fiber cores are occupied at the same time, a large cross crosstalk between the fiber cores is generated, and if the crosstalk value exceeds a certain range, the normal transmission of the optical signal in the optical fiber is interfered, and the transmission quality of the optical signal is affected. Therefore, in the spatial division multiplexing optical network based on the multi-core optical fiber, the cross-talk value needs to be controlled to be lower than the maximum tolerable cross-talk value threshold value by fully considering the inter-core cross-talk.
The routing and spectrum allocation problem is the core problem of the elastic optical network, and extends to the routing, fiber core and spectrum allocation problem in the spatial multiplexing optical network. In a single fiber core elastic optical network, a service searches for a spectrum resource required by a connection request by using a first hit or random hit method in a selected working path, and the selected spectrum resource only needs to meet two constraint conditions of spectrum continuity and spectrum consistency, because the traditional elastic optical network does not have the problem of crosstalk between adjacent fiber cores, and the influence of the spectrum overlapping degree of the adjacent fiber cores on cross-talk cannot be examined. However, in the sdm optical network, since the sdm optical network carries service traffic several times more than that of the conventional elastic optical network, it is necessary to effectively protect network data services and prevent service loss caused by network failure. Therefore, in the sdm optical network, the network survivability problem needs to be considered to ensure the fast recovery capability of the data service and ensure the transmission reliability of the data service. Dedicated path protection is one of the most common and effective protection methods. Generally, dedicated path protection establishes a link-disjoint protection path for each working path after the working path is established, and spectrum resources on the protection path cannot be shared but serve as dedicated backup spectrum resources.
Therefore, the problems of calculation of working paths and protection paths, selection of fiber cores and allocation of spectrum resources in the space division multiplexing elastic optical network of the data center network are solved.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the problems existing in the prior art, and provide a method and a system for allocating a dedicated protection spectrum for a spatial division multiplexing optical network in a data center, which solve the problems of routing calculation, fiber core selection and spectrum allocation based on crosstalk sensing, improve the spectrum resource efficiency of the spatial division multiplexing optical network, reduce the cross-talk value of each optical fiber link, and optimize the spectrum resources and cross-talk occupied by the working path and the dedicated protection path established by each connection request.
In order to solve the above technical problem, the present invention provides a method for allocating a dedicated protection spectrum for a space division multiplexing optical network in a data center, comprising the following steps:
s1: initializing a space division multiplexing elastic optical network facing a data center network;
s2: generating a connection request, wherein the connection request comprises a data center source node and a data center destination node;
s3: calculating the route of the connection request according to the data center source node and the data center destination node, calculating a plurality of working paths from the data center source node to the data center destination node and special protection paths which are not intersected with the working paths for the connection request, if the route establishment is successful, selecting the path with the shortest distance as the working path and the special protection path in descending order, and if the route establishment is failed, judging the connection request as blocking;
s4: calculating the idle spectrum availability value of each fiber core on the working path, and selecting the fiber core with the maximum idle spectrum availability value for transmission;
s5: searching available spectrum blocks meeting the constraints of spectrum consistency and continuity in a link selected from a working path and a fiber core used for transmission, if the available spectrum blocks meeting the requirements can be searched, calculating the crosstalk value of the fiber core of the available spectrum blocks, if the available spectrum blocks meeting the requirements cannot be searched, returning to S4, selecting the next fiber core in a descending order according to the availability value of the idle spectrum until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum blocks meeting the requirements do not exist in all fiber cores;
s6: judging whether the crosstalk value of the available frequency spectrum block is larger than the maximum allowable crosstalk value of the link or not, if not, reserving the available frequency spectrum block, if so, deleting the available frequency spectrum block, and continuing searching until all fiber cores are traversed, and judging the connection request as blocking when no available frequency spectrum block meeting the crosstalk requirement exists in all the fiber cores;
s7: calculating crosstalk values of available frequency spectrum blocks meeting the crosstalk requirements on all links of a working path in a fiber core for transmission, judging whether the crosstalk values on each link meet threshold requirements, if so, establishing a connection request, and if not, judging the connection request to be blocked;
s8: and repeating S4-S7 to complete the calculation of inter-fiber crosstalk and the spectrum allocation on the special protection path.
In one embodiment of the present invention, in S1, initializing a space division multiplexing flexible optical network facing a data center network includes:
initializing topological information of the space division multiplexing elastic optical network, link connection state, data center number, optical fiber link number, fiber core number of each optical fiber and frequency spectrum gap number of each optical fiber link.
In one embodiment of the present invention, in S4, calculating a free-spectrum availability value for each core on the working path includes:
calculating the free frequency spectrum availability value S of each fiber core i on the working path according to the following formulai：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
In one embodiment of the present invention, in S5, calculating the value of the crosstalk experienced by the core in the available spectrum block includes:
for available spectrum block
Calculating the value of the influence of crosstalk of adjacent cores on the frequency spectrum gap numbered j in the available frequency spectrum block according to the following formula
Wherein α and β areAdjustable factor, n represents and ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
the available spectrum blocks are calculated as follows
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of the crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing the coupling coefficient, the bending radius, the propagation coefficient and the fiber core spacing.
In one embodiment of the present invention, S9 is further included, and after all connection requests complete inter-core crosstalk calculation and spectrum allocation on the working path and the dedicated protection path, performance parameters of the network are evaluated.
In addition, the invention also provides a special protection spectrum allocation system for the space division multiplexing optical network of the data center, which comprises the following steps:
the network initialization module is used for initializing a space division multiplexing elastic optical network facing a data center network;
the connection request generating module is used for generating a connection request, wherein the connection request comprises a data center source node and a data center destination node;
a route calculation module, configured to calculate a route of the connection request according to the data center source node and the data center destination node, calculate multiple working paths from the data center source node to the data center destination node and dedicated protection paths that do not intersect with the working paths for the connection request, select, if the route establishment is successful, the path with the shortest distance in descending order as the working path and the dedicated protection path, and if the route establishment is failed, judge the connection request as a block;
the free spectrum available selection module is used for calculating a free spectrum availability value of each fiber core on the working path and selecting the fiber core with the largest free spectrum availability value for transmission;
the cross-talk constraint module is used for searching available spectrum blocks meeting the spectrum consistency and continuity constraints in a link selected from a working path and a fiber core used for transmission, if the available spectrum blocks meeting the requirements can be searched, calculating the crosstalk value of the fiber core of the available spectrum blocks, judging whether the crosstalk value of the available spectrum blocks is larger than the maximum allowable crosstalk value of the link, if the judgment result is negative, retaining the available spectrum blocks, if the judgment result is positive, deleting the available spectrum blocks, continuing searching until all fiber cores are traversed, and judging the connection request as blocking when no available spectrum block meeting the crosstalk requirements exists in all fiber cores; if the available spectrum block meeting the requirement cannot be found, returning to S4, selecting the next fiber core in a descending order according to the free spectrum availability value until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum block meeting the requirement is not available in all the fiber cores;
the spectrum allocation module is used for calculating crosstalk values of available spectrum blocks meeting the crosstalk requirements on all links of a working path in a fiber core for transmission, judging whether the crosstalk values on each link meet threshold requirements, if so, establishing a connection request, and if not, judging the connection request to be blocked; and repeating the working path crosstalk calculation and spectrum allocation process to complete the inter-fiber crosstalk calculation and spectrum allocation on the special protection path.
In one embodiment of the present invention, the white space available selection module includes:
a free spectrum availability calculation unit for calculating a free spectrum availability value S of each fiber core i on the working path according to the following formulai：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
In one embodiment of the present invention, the white space available selection module includes:
and the fiber core selection unit is used for arranging the fiber cores in a descending order according to the idle spectrum availability value and selecting the fiber core with the maximum idle spectrum availability value for transmission.
In one embodiment of the present invention, the cross-talk constraint module comprises:
a cross-talk calculation module, configured to calculate a crosstalk value of the fiber core suffered by the available spectrum block, including:
for available spectrum block
Calculating the value of the influence of crosstalk of adjacent cores on the frequency spectrum gap numbered j in the available frequency spectrum block according to the following formula
Wherein alpha and beta are adjustable factors, n represents the same as ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
the available spectrum blocks are calculated as follows
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of the crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing the coupling coefficient, the bending radius, the propagation coefficient and the fiber core spacing.
In one embodiment of the present invention, further comprising:
and the network performance evaluation module is used for evaluating the performance parameters of the network after all the connection requests complete the inter-fiber crosstalk calculation and the spectrum allocation on the working path and the special protection path.
Compared with the prior art, the technical scheme of the invention has the following advantages:
the invention solves the problems of route calculation, fiber core selection and spectrum allocation based on crosstalk sensing, improves the spectrum resource efficiency of the space division multiplexing optical network, reduces the cross crosstalk value of each optical fiber link, and optimizes the spectrum resources and the cross crosstalk occupied by the working path and the special protection path established by each connection request.
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In order that the present disclosure may be more readily and clearly understood, reference will now be made in detail to the present disclosure, examples of which are illustrated in the accompanying drawings.
Fig. 1 is a schematic flow chart of a method for allocating dedicated protection spectrum for a spatial division multiplexing optical network in a data center according to the present invention.
Fig. 2 is a schematic diagram of a hardware structure of a dedicated protection spectrum allocation system for a spatial division multiplexing optical network of a data center according to the present invention.
Figure 3 is a diagram of the NSFNET network topology of the present invention.
FIG. 4 is a schematic view of a trench assist structure of the seven-core optical fiber of the present invention.
Fig. 5 is a schematic illustration of the numbering and arrangement of the seven-core optical fibers of the present invention.
Fig. 6 is a schematic diagram of the spectrum occupation state on the working path of the present invention.
Wherein the reference numerals are as follows: 10. a network initialization module; 20. a connection request generation module; 30. a route calculation module; 40. a free spectrum available selection module; 50. a cross-talk constraint module; 60. a spectrum allocation module; 70. a network performance evaluation module; 80. a network state monitoring module; 90. and a judgment early warning module.
Detailed Description
The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.
Referring to fig. 1, the present embodiment provides a method for allocating dedicated protection spectrum for space division multiplexing optical network in a data center, including the following steps:
s1: initializing a space division multiplexing elastic optical network facing a data center network;
s2: generating a connection request, wherein the connection request comprises a data center source node and a data center destination node;
s3: calculating the route of the connection request according to the data center source node and the data center destination node, calculating a plurality of working paths from the data center source node to the data center destination node and special protection paths which are not intersected with the working paths for the connection request, if the route establishment is successful, selecting the path with the shortest distance as the working path and the special protection path in descending order, and if the route establishment is failed, judging the connection request as blocking;
s4: calculating the idle spectrum availability value of each fiber core on the working path, and selecting the fiber core with the maximum idle spectrum availability value for transmission;
s5: searching available spectrum blocks meeting the constraints of spectrum consistency and continuity in a link selected from a working path and a fiber core used for transmission, if the available spectrum blocks meeting the requirements can be searched, calculating the crosstalk value of the fiber core of the available spectrum blocks, if the available spectrum blocks meeting the requirements cannot be searched, returning to S4, selecting the next fiber core in a descending order according to the availability value of the idle spectrum until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum blocks meeting the requirements do not exist in all fiber cores;
s6: judging whether the crosstalk value of the available frequency spectrum block is larger than the maximum allowable crosstalk value of the link or not, if not, reserving the available frequency spectrum block, if so, deleting the available frequency spectrum block, and continuing searching until all fiber cores are traversed, and judging the connection request as blocking when no available frequency spectrum block meeting the crosstalk requirement exists in all the fiber cores;
s7: calculating crosstalk values of available frequency spectrum blocks meeting the crosstalk requirements on all links of a working path in a fiber core for transmission, judging whether the crosstalk values on each link meet threshold requirements, if so, establishing a connection request, and if not, judging the connection request to be blocked;
s8: and repeating S4-S7 to complete the calculation of inter-fiber crosstalk and the spectrum allocation on the special protection path.
In S1, initializing the sdm resilient optical network facing the data center network includes:
initializing topological information of the space division multiplexing elastic optical network, link connection state, data center number, optical fiber link number, fiber core number of each optical fiber and frequency spectrum gap number of each optical fiber link.
In a preferred embodiment, the space division multiplexing elastic optical network is represented by G (E, V, C, F), where E ═ E { (E)1,E2,…,E|E|}、V＝{V1,V2,…,V|V|}、C＝{C1,C2,…,C|C|}、F＝{F1,F2,…,F|F|Respectively representing the collection of optical fiber links, data centers, fiber cores and available frequency spectrums in the space division multiplexing elastic optical network of the data center, | E |, | V |, | C |, and | F |, respectively representing the number of the optical fiber links, the number of the data centers, the number of the fiber cores and the number of the frequency spectrum slots of each fiber core in the space division multiplexing elastic optical network, (V |, | C |, andi,Vj) E, wherein Vi,VjE.g. V, represents the slave data center ViTo data center VjThe optical fiber link of (1).
In S4, calculating a free-spectrum availability value for each core on the working path includes:
calculating the free spectrum availability value S of each fiber core i on the working path according to the formula (1)i：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
After the free spectrum availability value of each fiber core is obtained through calculation, the fiber cores are arranged in a descending order according to the free spectrum availability value, and the fiber cores are selected in the descending order for transmission.
In S5, calculating the crosstalk value of the available spectrum block on the core includes:
s5.1: for available spectrum block
Calculating the influence value of the frequency spectrum gap numbered j in the available frequency spectrum block on the crosstalk of the adjacent cores according to the formula (2)
Wherein alpha and beta are adjustable factors, n represents the same as ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
s5.2: calculating available spectrum blocks according to equation (3)
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing coupling coefficient, bending radius, propagation coefficient and fiberCore pitch.
The above-mentioned available spectrum block is obtained by calculation
Cross talk value of
Then, will
Maximum allowable crosstalk value with current link
In comparison, if
Reserved spectrum block
If it is
Deleting spectral blocks
And continuing searching, and judging the connection request as blocking if the spectrum block meeting the crosstalk requirement cannot be found by traversing all fiber cores.
And S9, evaluating the performance parameters of the network after all the connection requests complete the calculation of inter-core crosstalk and spectrum allocation on the working path and the special protection path.
Referring to fig. 2, the present embodiment further provides a system for allocating dedicated protection spectrum for space division multiplexing optical network in a data center, including:
a network initialization module 10, where the network initialization module 10 is configured to initialize a space division multiplexing (sdm) elastic optical network facing a data center network;
a connection request generating module 20, where the connection request generating module 20 is configured to generate a connection request, where the connection request includes a data center source node and a data center destination node;
a route calculation module 30, where the route calculation module 30 is configured to calculate a route of the connection request according to the data center source node and the data center destination node, calculate a plurality of working paths from the data center source node to the data center destination node and dedicated protection paths that do not intersect with the working paths for the connection request, if the route establishment is successful, select a path with a shortest distance as the working path and the dedicated protection path in descending order, and if the route establishment is failed, judge the connection request as a block;
a free spectrum availability selection module 40, where the free spectrum availability selection module 40 is configured to calculate a free spectrum availability value of each fiber core on the working path, and select a fiber core with a largest free spectrum availability value for transmission;
a cross-talk constraint module 50, where the cross-talk constraint module 50 is configured to search for an available spectrum block that meets the constraints of spectrum consistency and continuity in a link and a fiber core used for transmission selected from a working path, and if the available spectrum block that meets the requirements can be found, calculate a crosstalk value of the fiber core of the available spectrum block, and determine whether the crosstalk value of the available spectrum block is greater than a maximum allowable crosstalk value of the link, if the determination result is negative, retain the available spectrum block, if the determination result is positive, delete the available spectrum block, and continue searching until all fiber cores are traversed, and when there is no available spectrum block that meets the crosstalk requirements in all fiber cores, judge the connection request as blocking; if the available spectrum block meeting the requirement cannot be found, returning to S4, selecting the next fiber core in a descending order according to the free spectrum availability value until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum block meeting the requirement is not available in all the fiber cores;
a spectrum allocation module 60, where the spectrum allocation module 60 is configured to calculate crosstalk values of available spectrum blocks meeting the crosstalk requirement on all links of a working path in a fiber core used for transmission, determine whether the crosstalk value on each link meets a threshold requirement, if the determination result is yes, establish a connection request, and if the determination result is no, judge the connection request as blocking; and repeating the working path crosstalk calculation and spectrum allocation process to complete the inter-fiber crosstalk calculation and spectrum allocation on the special protection path.
Wherein the idle spectrum available selection module 40 includes:
a free spectrum availability calculation unit for calculating a free spectrum availability value S of each fiber core i on the working path according to the formula (1)i：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
Wherein the idle spectrum available selection module 40 includes:
and the fiber core selection unit is used for arranging the fiber cores in a descending order according to the idle spectrum availability value and selecting the fiber core with the maximum idle spectrum availability value for transmission.
Wherein the cross-talk constraint module 50 comprises:
a cross-talk calculation module, configured to calculate a crosstalk value of the fiber core suffered by the available spectrum block, including:
for available spectrum block
Calculating the influence value of the frequency spectrum gap numbered j in the available frequency spectrum block on the crosstalk of the adjacent cores according to the formula (2)
Wherein alpha and beta are adjustable factors, n represents the same as ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
calculating available spectrum blocks according to equation (3)
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of the crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing the coupling coefficient, the bending radius, the propagation coefficient and the fiber core spacing.
A network performance evaluation module 70 is further included, and is configured to evaluate performance parameters of the network after all connection requests complete inter-fiber crosstalk calculation and spectrum allocation on the working path and the dedicated protection path.
The system further comprises a network state monitoring module 80, wherein the network state monitoring module 80 mainly completes the monitoring functions of the states of space division multiplexing elastic optical network parameter initialization, connection request generation, routing calculation, idle spectrum availability calculation, fiber core selection, cross crosstalk calculation, spectrum resource allocation, network performance evaluation and the like of the data center.
The system also comprises a judgment early warning module 90, wherein the judgment early warning module 90 is used for executing the coordination function among the modules, judging whether each module is successfully established or not and early warning function, so that the purposes of routing, fiber core and spectrum distribution in the space division multiplexing elastic optical network of the data center are fulfilled, the network performance is improved and the cross-talk value is reduced.
The NSFNET network topology shown in fig. 3 includes 14 nodes and 21 bidirectional links, the numerical value on the optical fiber link indicates the length of the link, the unit is km, the spectral bandwidth of each link is set to 200GHz, the bandwidth of each spectral slot is set to 12.5GHz, that is, each fiber core includes 16 spectral slots, each optical fiber link uses a seven-core optical fiber, the seven-core optical fiber adopts a groove auxiliary structure shown in fig. 4, and values of parameters in the optical fiber are respectively set as: k is 3.16 × 10-5、r＝55(mm)、β＝4×106Λ 45(μm), then
Let the connection request currently arriving at the network be CR1(2,11), K is 3, the operation path is (2,5,12,11) according to the K shortest path algorithm, and according to the previous research, the maximum allowable crosstalk value of each link on the path is set to be all
The numbering and arrangement of the seven-core fibers is shown in fig. 5. Hypothesis CR1(2,11,2) the spectral occupancy state in the core is shown in FIG. 6, where the grey color indicates that the spectral slot is already occupied. According to equation (1), link l is based on spectral continuity1Upper core c1Has SS as the optional spectrum block in1,1、SS2,1And SS3,1Link l2Upper core c1Has SS as the optional spectrum block in1,1And SS2,1Link l3Upper core c1Has SS as the optional spectrum block in1,1、SS2,1And SS3,1. Thus, the core c1Has a free spectrum availability value of S1By analogy with 8, the core c can be obtained2Idle spectrum availability value ofIs S2Core c of 53Has a free spectrum availability value of S 37, core c4Has a free spectrum availability value of S 46, core c5Has a free spectrum availability value of S 54, core c6Has a free spectrum availability value of S 66, core c7Has a free spectrum availability value of S 76. Thus, the core c is preferred1And carrying out transmission. Let τ0＝0.5，τ1At link l, then1Above, the fiber link length is 1300(km), and the spectral blocks numbered 3 and 4 are first calculated according to the spectral consistency constraint and first hit method
On the link l1Upper value influenced by crosstalk of adjacent cores
And the value of crosstalk between cores
Because of the fact that
So will
And (5) deleting. In turn, the spectral blocks numbered 4 and 5 are calculated
On the link l1The crosstalk influence value of adjacent fiber cores and the cross-crosstalk value between the fiber cores: because of the fact that
So as to protectLeave behind
On the link l2And the upper link length is 1400(km),
and satisfying the crosstalk threshold constraint and reserving. On the link l3And the upper, link length is 300(km),
satisfying the crosstalk threshold constraint, and finally selecting the idle frequency spectrum blocks numbered 4 and 5
Then is CR1And establishing a special protection path (2,1,7,9,11) without repeated links with the working path, and repeating the calculation and selection processes according to the spectrum occupation state on each link.
The establishment of the other connection requests is similar to that described above.
Firstly, establishing a working path and a special protection path for each connection request to ensure the survivability of the space division multiplexing optical network of the data center; secondly, in order to reduce the generation of spectrum fragments, calculating the idle spectrum availability values of all fiber cores according to the spectrum use conditions on each optical fiber link, arranging the idle spectrum availability values in a descending order, and sequentially selecting the fiber cores; then, under the constraints of spectrum continuity and consistency, selecting an available spectrum block and calculating a crosstalk value of the spectrum block on each link; and then, judging whether the crosstalk value on each link meets the limit of a crosstalk threshold value, if so, reserving the frequency spectrum block, and performing frequency spectrum allocation, so that the problems of routing calculation, fiber core selection and frequency spectrum allocation based on crosstalk sensing are solved, the frequency spectrum resource efficiency of the space division multiplexing optical network is improved, the cross crosstalk value of each optical fiber link is reduced, and the frequency spectrum resources and the cross crosstalk occupied by the working path and the special protection path established by each connection request are optimized.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. A method for distributing special protection frequency spectrum for a space division multiplexing optical network of a data center is characterized by comprising the following steps:
s1: initializing a space division multiplexing elastic optical network facing a data center network;
s2: generating a connection request, wherein the connection request comprises a data center source node and a data center destination node;
s3: calculating the route of the connection request according to the data center source node and the data center destination node, calculating a plurality of working paths from the data center source node to the data center destination node and special protection paths which are not intersected with the working paths for the connection request, if the route establishment is successful, selecting the path with the shortest distance as the working path and the special protection path in descending order, and if the route establishment is failed, judging the connection request as blocking;
s4: calculating the idle spectrum availability value of each fiber core on the working path, and selecting the fiber core with the maximum idle spectrum availability value for transmission;
s5: searching available spectrum blocks meeting the constraints of spectrum consistency and continuity in a link selected from a working path and a fiber core used for transmission, if the available spectrum blocks meeting the requirements can be searched, calculating the crosstalk value of the fiber core of the available spectrum blocks, if the available spectrum blocks meeting the requirements cannot be searched, returning to S4, selecting the next fiber core in a descending order according to the availability value of the idle spectrum until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum blocks meeting the requirements do not exist in all fiber cores;
s6: judging whether the crosstalk value of the available frequency spectrum block is larger than the maximum allowable crosstalk value of the link or not, if not, reserving the available frequency spectrum block, if so, deleting the available frequency spectrum block, and continuing searching until all fiber cores are traversed, and judging the connection request as blocking when no available frequency spectrum block meeting the crosstalk requirement exists in all the fiber cores;
s7: calculating crosstalk values of available frequency spectrum blocks meeting the crosstalk requirements on all links of a working path in a fiber core for transmission, judging whether the crosstalk values on each link meet threshold requirements, if so, establishing a connection request, and if not, judging the connection request to be blocked;
s8: and repeating S4-S7 to complete the calculation of inter-fiber crosstalk and the spectrum allocation on the special protection path.
2. The method according to claim 1, wherein initializing the sdm resilient optical network facing the data center network in S1 comprises:
initializing topological information of the space division multiplexing elastic optical network, link connection state, data center number, optical fiber link number, fiber core number of each optical fiber and frequency spectrum gap number of each optical fiber link.
3. The method according to claim 1, wherein in S4, calculating the free spectrum availability value for each core on the working path includes:
calculating the free frequency spectrum availability value S of each fiber core i on the working path according to the following formulai：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
4. The method of claim 1, wherein the step of calculating the crosstalk value of the available spectrum block on the fiber core in S5 includes:
for available spectrum block
Calculating the value of the influence of crosstalk of adjacent cores on the frequency spectrum gap numbered j in the available frequency spectrum block according to the following formula
Wherein alpha and beta are adjustable factors, n represents the same as ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
the available spectrum blocks are calculated as follows
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of the crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing the coupling coefficient, the bending radius, the propagation coefficient and the fiber core spacing.
5. The method for allocating dedicated guard spectrum for spatial division multiplexing optical networks of data centers according to claim 1, further comprising step S9, when all connection requests complete inter-core crosstalk calculation and spectrum allocation on working paths and dedicated guard paths, evaluating performance parameters of the network.
6. A system for allocating dedicated protection spectrum for a space division multiplexing optical network in a data center is characterized by comprising:
the network initialization module is used for initializing a space division multiplexing elastic optical network facing a data center network;
the connection request generating module is used for generating a connection request, wherein the connection request comprises a data center source node and a data center destination node;
a route calculation module, configured to calculate a route of the connection request according to the data center source node and the data center destination node, calculate multiple working paths from the data center source node to the data center destination node and dedicated protection paths that do not intersect with the working paths for the connection request, select, if the route establishment is successful, the path with the shortest distance in descending order as the working path and the dedicated protection path, and if the route establishment is failed, judge the connection request as a block;
the free spectrum available selection module is used for calculating a free spectrum availability value of each fiber core on the working path and selecting the fiber core with the largest free spectrum availability value for transmission;
the cross-talk constraint module is used for searching available spectrum blocks meeting the spectrum consistency and continuity constraints in a link selected from a working path and a fiber core used for transmission, if the available spectrum blocks meeting the requirements can be searched, calculating the crosstalk value of the fiber core of the available spectrum blocks, judging whether the crosstalk value of the available spectrum blocks is larger than the maximum allowable crosstalk value of the link, if the judgment result is negative, retaining the available spectrum blocks, if the judgment result is positive, deleting the available spectrum blocks, continuing searching until all fiber cores are traversed, and judging the connection request as blocking when no available spectrum block meeting the crosstalk requirements exists in all fiber cores; if the available spectrum block meeting the requirement cannot be found, returning to S4, selecting the next fiber core in a descending order according to the free spectrum availability value until all fiber cores are traversed, and judging the connection request as blocking when the available spectrum block meeting the requirement is not available in all the fiber cores;
the spectrum allocation module is used for calculating crosstalk values of available spectrum blocks meeting the crosstalk requirements on all links of a working path in a fiber core for transmission, judging whether the crosstalk values on each link meet threshold requirements, if so, establishing a connection request, and if not, judging the connection request to be blocked; and repeating the working path crosstalk calculation and spectrum allocation process to complete the inter-fiber crosstalk calculation and spectrum allocation on the special protection path.
7. The system of claim 6, wherein the free spectrum availability selection module comprises:
a white space availability calculation unit forCalculating the free frequency spectrum availability value S of each fiber core i on the working path according to the following formulai：
Wherein L represents the number of links on the current working path, | F represents the number of spectral slots per fiber core, Sk,iAnd F, the spectrum block which represents that the number of the k-th idle spectrum gaps on the fiber core i is more than or equal to FS, wherein the FS represents the number of the spectrum gaps required by the connection request.
8. The system according to claim 6 or 7, wherein the free spectrum availability selection module comprises:
and the fiber core selection unit is used for arranging the fiber cores in a descending order according to the idle spectrum availability value and selecting the fiber core with the maximum idle spectrum availability value for transmission.
9. The system according to claim 6, wherein the cross-talk constraint module comprises:
a cross-talk calculation module, configured to calculate a crosstalk value of the fiber core suffered by the available spectrum block, including:
for available spectrum block
Calculating the value of the influence of crosstalk of adjacent cores on the frequency spectrum gap numbered j in the available frequency spectrum block according to the following formula
Wherein alpha and beta are adjustable factors, n represents the same as ciThe set of adjacent cores is then assembled,
for binary variables, taking 1 indicates the sum over link l and ciThe frequency spectrum gap numbered j in the adjacent fiber core r is already occupied, and 0 is taken to represent that the fiber core is not occupied;
the available spectrum blocks are calculated as follows
Cross talk value of
Wherein n is the same as the selected core ciThe number of adjacent fiber cores, L is the length of the current link L,
is the average increase value of the crosstalk between fiber cores in unit fiber length, and k, r, beta and Lambda are fiber parameters respectively representing the coupling coefficient, the bending radius, the propagation coefficient and the fiber core spacing.
10. The system of claim 6, further comprising:
and the network performance evaluation module is used for evaluating the performance parameters of the network after all the connection requests complete the inter-fiber crosstalk calculation and the spectrum allocation on the working path and the special protection path.
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