OTN network service failure recovery method and system

Abstract

The present disclosure relates to the technical field of OTN optical network routing computation, and in particular to an OTN network service failure recovery method and system. The method comprises: establishing a first objective function, and setting first constraint conditions for the first objective function; on the basis of the first objective function, determining an available path of a service to be recovered; establishing a second objective function on the basis of the available path of said service, and setting second constraint conditions for the second objective function; and determining a target path of said service on the basis of the second objective function, and performing failure recovery on the target path. In the present disclosure, a two-stage model of a faulty network is accurately constructed, and the two-stage model can significantly reduce computational complexity.

Description

A method and system for recovering OTN network service faults Technical Field

[0001] This disclosure belongs to the field of OTN optical network routing calculation technology, and specifically relates to an OTN network service fault recovery method and system. Background Technology

[0002] Once an OTN network is built, network failures frequently occur during its operation, such as node power outages and link interruptions. These failures can generally be translated into link failures; for example, when a node loses power, all links connected to that node become unavailable. Therefore, a node failure can be interpreted as a failure of all links connected to that node. After a link failure, services passing through that link will be interrupted. The challenge is to quickly restore service routing and minimize customer disruption.

[0003] In the field of optical communication transmission, the typical spectral range of the C-band is 196.675 Thz to 190.675 Thz, while the L-band ranges from 190.325 Thz to 184.325 Thz. With breakthroughs in optical devices, L-band channels can now successfully transmit optical signals, necessitating the adaptation of routing algorithms for the C+L band. There is a 0.35 Thz interval between the C-band and L-band. One of the differences between C+L band routing calculations and C-band routing calculations lies in how to unify these discontinuous channels. Furthermore, the amplification effect of optical amplifiers differs between the C-band and L-band, requiring separate consideration of the optical signal-to-noise ratio for each channel.

[0004] This disclosure focuses on the issue of service routing recovery in OTN networks. With continuous breakthroughs in optical communication transmission capacity, the current capacity has expanded from the C-band to the C+L band, and may be further expanded to the S+C+L full band in the future. Currently, we are in the early trial phase of C+L. This breakthrough in transmission capacity has brought new challenges to service routing recovery in optical transmission networks. For example, optical modules and repeaters cannot fully support both C and L bands simultaneously; in a recovery network, repeater reuse can only be used by services that occupied that repeater before the fault occurred; and channels used by services that did not experience a fault cannot be used by other recovery services in a recovery scenario. Summary of the Invention

[0005] To address the above problems, this disclosure provides a method for recovering OTN network service faults, the method comprising:

[0006] Establish a first objective function and set a first constraint condition for the first objective function;

[0007] Based on the first objective function, determine the available paths for the services to be restored;

[0008] A second objective function is established based on the available paths of the services to be restored, and a second constraint condition is set for the second objective function;

[0009] Based on the second objective function, the target path of the service to be restored is determined, and fault recovery is performed on the target path.

[0010] Preferably, establishing the first objective function includes:

[0011] Obtain path data in the faulty network;

[0012] The path data is weighted and summed to obtain the first objective function.

[0013] Preferably, the path data in the faulty network includes: the number of services successfully restored in the faulty network, the total length or total number of links, the number of newly added relays, and the number of relays used that have been reduced.

[0014] Preferably, the first constraint includes: source and destination node constraints, path connectivity constraints, anti-loop constraints, OSNR constraints, link wavelength constraints, and the number of relays on the node.

[0015] Preferably, the source and destination node constraints include: only one link from the target source node to the target service meets the requirements; only one link from the target service to all destination nodes meets the requirements.

[0016] The path connectivity constraints include: each sub-path of the target service is a link that connects end to end; the h-th sub-path and h+1-th sub-path of the target service are links that connect end to end; the number of services entering a sub-path is the same as the number of links exiting a sub-path.

[0017] The anti-loop constraint includes: the number of links entering the target node is less than or equal to one; the number of links leaving the target node is less than or equal to one.

[0018] The OSNR constraint includes: the OSNR attenuation values ​​of C-band and L-band in the target service meet the threshold requirements;

[0019] The link wavelength constraints include: the number of services passing through each link is less than the number of channels that the link can support; the number of C-band services passing through the target link is less than the number of C-channels on the link; and the number of L-band services passing through the target link is less than the number of L-channels on the link.

[0020] The constraints on the number of relays on the node include: the reusable relays on the target node can only be used for services that were originally occupied by the relays before the failure.

[0021] Preferably, after constructing the first constraint condition for the coefficients in the first objective function, the method further includes:

[0022] Determine whether the coefficients in the first objective function satisfy the first constraint condition;

[0023] If the condition is not met, a relay is added to the node.

[0024] Preferably, the variables are determined when the source and destination ports of the p-th sub-path of the target service are io path wavelength w and when the source and destination ports of the p-th sub-path of the target service are r relays;

[0025] The second objective function is obtained by weighting the variables when the source and destination ports of the p-th sub-path of the target service are r relays and summing them with the variables when the source and destination ports of the p-th sub-path of the target service are io paths with wavelength w.

[0026] Preferably, the second constraint includes: source-destination constraint, relay point constraint, local group constraint at both ends of the relay, relay constraint, available wavelength constraint of the relay, local group wavelength usage constraint, and link wavelength usage constraint.

[0027] Preferably, the source-destination constraint includes: the target service has only one path or no path from the target point; the target service has only one path or no path back to the target point.

[0028] The relay point constraints include: the number of m-1 sub-paths of the target service is the same as the number of m-th sub-paths; the o-local group of sub-path m-1 of the target service and the i-local group of sub-path m are the same relay.

[0029] The local group constraints at both ends of the relay include: the local groups at both ends of the relay cannot be the same;

[0030] The relay constraints include: each relay can only be used once;

[0031] The wave constraints available to the relay include: each relay can only use the wave available to that relay;

[0032] The local group wavelength usage constraints include: each wavelength in the local group can only be used once;

[0033] The link wavelength usage constraints include: each wavelength can only be used once.

[0034] This disclosure also proposes an OTN network service fault recovery system, the system comprising:

[0035] The first establishment module is used to establish a first objective function and set first constraints for the first objective function;

[0036] The first determining module is used to determine the available path for the service to be restored based on the first objective function;

[0037] The second establishment module is used to establish a second objective function based on the available paths of the service to be restored, and to set a second constraint condition for the second objective function;

[0038] The second determining module is used to determine the target path of the service to be restored based on the second objective function, and to perform fault recovery for the target path.

[0039] This disclosure has the following beneficial effects:

[0040] (1) This disclosure accurately constructs a two-stage model of the fault network, which can significantly reduce computational complexity;

[0041] (2) The linear programming solver in this disclosure can provide accurate results in the small programming scenario, provide the optimal solution for the company's centralized procurement verification in the small programming scenario, and enhance the company's overall competitiveness; while obtaining the maximum business recovery rate, it can ensure a significant reduction in the number of relays;

[0042] (3) This disclosure simplifies the OSNR model, making the OSNR value of the business path linear. A linear model is a prerequisite for accurately solving this problem.

[0043] Other features and advantages of this disclosure will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 illustrates a method for recovering OTN network service faults in an embodiment of this disclosure.

[0046] Figure 2 shows a schematic diagram of an optical transmission network in an embodiment of this disclosure;

[0047] Figure 3 illustrates an OTN network service fault recovery system diagram in an embodiment of this disclosure;

[0048] Figure 4 shows a diagram of an OTN network service fault recovery device in an embodiment of this disclosure. Detailed Implementation

[0049] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of the specific details omitted, or other methods, components, apparatus, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0050] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware units or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0051] The flowchart shown in the attached diagram is merely an illustrative example and does not necessarily include all steps. For example, some steps may be broken down, while others may be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0052] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0053] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or device that includes a series of steps or sub-modules is not necessarily limited to those steps or sub-modules that are explicitly listed, but may include other steps or sub-modules that are not explicitly listed or that are inherent to such process, method, product, or device.

[0054] The technical problem this disclosure aims to solve is as follows: Given an optical transmission network, denoted by (N,E), where N is the set of nodes and E is the set of links. Let n∈N represent a node in the network, which is an optical add-drop multiplexing node. Optical services are initiated at the node through a line port to the local group, which then connects to the remote group. The remote group connects to the remote groups of other nodes. (i,j)∈E represents the link between node i and node j, where the link is an optical fiber link. Specifically, it connects the remote groups of node i and node j. The optical signal propagates in the optical fiber. The optical fiber channel has a limited spectral range that can transmit light; currently, the C+L band is mature, and it may be extended to the S+C+L band in the future. Let t... k Let ∈T represent an optical service in an optical transmission network, where T is the set of all services in the network. Under normal circumstances, the paths and resources for all services are deterministic. When a link failure occurs, the services existing on those links will be interrupted, requiring recalculation of paths and resources for these services. The goal is to restore services in the current faulty network as much as possible, with the fewest newly added and reused relays. In the faulty network, the services that need to be restored are deterministic, denoted by t. k Let 'k' represent the service that needs to be restored in the faulty network; let 'irj' represent a reusable relay 'r' at node i, where r = 0 indicates a newly added relay. Light attenuates during transmission in fiber optic channels, and the attenuation values ​​differ between C-band and L-band. For each link (i,j), the attenuation value 'clf' can be used. ij To represent the attenuation of the C-band, llf ij The attenuation in the L-band is represented by |w|. A path consists of links connected end-to-end without loops, and its attenuation value can be represented by the sum of the attenuation values ​​of the links along the path. The spectral bandwidth within each optical fiber is finite, denoted by |w|. ij | represents the number of C+L channels in the link, where |W Cij | represents the number of available spectrum bands in the C-band, |W lij | indicates the amount of spectrum available in the L-band; the number of services on each link cannot exceed a certain percentage of the channel resources on that link; the channel set for the C-band range is represented by W. Cij The channel set within the L-channel range is represented by W. Lij This is represented by the formula. Each spectrum resource in each chain can only be occupied by one service. The path and resources need to be recalculated for each service to be restored. A path is a set of interconnected, non-looping links. Harajuku line ports, channels, and relays also need to be allocated to this service. All restored services should be considered together to maximize service recovery while minimizing the number of new and reused relays.

[0055] In addition, it is necessary to consider that when a service is not experiencing a fault, its line port, local group, and trunk cannot be used by other services after the fault is recovered. For this service, its resources include the resources it has when it is not experiencing a fault, as well as the resources that are not used by other services.

[0056] The technical solution adopted by this disclosure to solve the above-mentioned technical problem is as follows: First, an accurate two-stage data model of the problem is constructed. The first stage establishes a model for solving accurate paths and whether these paths have sufficient relay, local group, and wavelength resources. The first-stage model is solved using a linear programming solver to calculate the path for each faulty service. The second stage establishes an allocation model for local groups, relays, and wavelengths for all paths (calculated in the first stage). The second-stage model calculates the local groups, relays, and wavelengths for each path by calling a linear programming solver.

[0057] This disclosure requires the highest possible recovery rate of fiber-broken services in a faulty network, the fewest possible number of new relays, the lowest possible total network path hops, and the least possible use of reused relays; this is a multi-objective optimization problem. Optical communication networks also face many physical constraints to ensure smooth service transmission, including:

[0058] 1. An optical channel can only be used by one service. Here, the optical channel is light of a specific frequency.

[0059] 2. Once a specific frequency of light on a link is occupied, that specific frequency of light cannot be occupied again;

[0060] 3. Business connectivity requirement, that is, the path of this business must be connected end to end;

[0061] 4. Business paths cannot form loops;

[0062] 5. The source and destination nodes of the business path must be the source and destination nodes of the business;

[0063] 6. Optical signals will attenuate to a certain extent when they are transmitted in optical fibers. When the optical signal attenuates to below the OSNR threshold, it must be converted from photoelectric to optical signal through a repeater in order to restore the signal. Therefore, services also need to meet OSNR constraints.

[0064] 7. The number of relays on each node is limited, so the number of relays added to a node cannot exceed the maximum number of relays on that node; there are also many other constraints, such as whether relays can pass through the same local group at the same time; the number of relays occupied by the original route of a service can only be restored and used by that service itself and cannot be used by other services; the number of newly added relays in different faulty networks can be reused; constraints containing a certain resource can also be added, etc.

[0065] To address the above objectives and constraints, this disclosure establishes an accurate mathematical model, which is constructed as much as possible as an integer linear programming model. For the integer linear programming model, the exact solution to the problem in the case of miniprogramming can be calculated using linear programming solvers such as Cplex and Gurobi. When the problem size is further expanded, an approximate solution to the problem will be obtained through some heuristic or approximation algorithms.

[0066] As shown in Figure 1, this disclosure proposes an OTN network service fault recovery method, the method comprising:

[0067] Establish a first objective function and set a first constraint condition for the first objective function;

[0068] Based on the first objective function, determine the available paths for the services to be restored;

[0069] A second objective function is established based on the available paths of the services to be restored, and a second constraint condition is set for the second objective function;

[0070] Based on the second objective function, the target path of the service to be restored is determined, and fault recovery is performed on the target path.

[0071] Specifically, establishing the first objective function includes:

[0072] Obtain path data in the faulty network;

[0073] The path data is weighted and summed to obtain the first objective function.

[0074] Specifically, the path data in the faulty network includes: the number of services successfully restored in the faulty network, the total length or total number of links, the number of newly added relays, and the number of relays used that have been reduced.

[0075] Specifically, the first constraint includes: source and destination node constraints, path connectivity constraints, anti-loop constraints, OSNR constraints, link wavelength constraints, and the number of relays on the node.

[0076] Specifically, the source and destination node constraints include: only one link from the target source node to the target service meets the requirements; only one link from the target service to all destination nodes meets the requirements.

[0077] The path connectivity constraints include: each sub-path of the target service is a link that connects end to end; the h-th sub-path and h+1-th sub-path of the target service are links that connect end to end; the number of services entering a sub-path is the same as the number of links exiting a sub-path.

[0078] The anti-loop constraint includes: the number of links entering the target node is less than or equal to one; the number of links leaving the target node is less than or equal to one.

[0079] The OSNR constraint includes: the OSNR attenuation values ​​of C-band and L-band in the target service meet the threshold requirements;

[0080] The link wavelength constraints include: the number of services passing through each link is less than the number of channels that the link can support; the number of C-band services passing through the target link is less than the number of C-channels on the link; and the number of L-band services passing through the target link is less than the number of L-channels on the link.

[0081] The constraints on the number of relays on the node include: the reusable relays on the target node can only be used for services that were originally occupied by the relays before the failure.

[0082] Specifically, after constructing the first constraint condition for the coefficients in the first objective function, the method further includes:

[0083] Determine whether the coefficients in the first objective function satisfy the first constraint condition;

[0084] If the condition is not met, a relay is added to the node.

[0085] Specifically, the establishment of the second objective function based on the available paths of the service to be restored includes:

[0086] The variables are determined when the source and destination ports of the p-th sub-path of the target service are io paths with wavelength w, and when the source and destination ports of the p-th sub-path of the target service are r relays.

[0087] The second objective function is obtained by weighting the variables when the source and destination ports of the p-th sub-path of the target service are r relays and summing them with the variables when the source and destination ports of the p-th sub-path of the target service are io paths with wavelength w.

[0088] Specifically, the second constraint includes: source-destination constraint, relay point constraint, local group constraint at both ends of the relay, relay constraint, available wavelength constraint of the relay, local group wavelength usage constraint, and link wavelength usage constraint.

[0089] Specifically, the source-destination constraints include: the target service has only one path or no path from the target point; the target service has only one path or no path back to the target point.

[0090] The relay point constraints include: the number of m-1 sub-paths of the target service is the same as the number of m-th sub-paths; the o-local group of sub-path m-1 of the target service and the i-local group of sub-path m are the same relay.

[0091] The local group constraints at both ends of the relay include: the local groups at both ends of the relay cannot be the same;

[0092] The relay constraints include: each relay can only be used once;

[0093] The wave constraints available to the relay include: each relay can only use the wave available to that relay;

[0094] The local group wavelength usage constraints include: each wavelength in the local group can only be used once;

[0095] The link wavelength usage constraints include: each wavelength can only be used once.

[0096] This method solves the technical problem in two steps:

[0097] Step 1: Path and resource calculation (This step does not distinguish between resources, but only calculates the satisfiability of resources)

[0098] Objective function:

[0099] Among them, t k Indicates whether the new path for business k can be recovered;

[0100] ∑ k t k This indicates the number of services that were successfully restored in the faulty network;

[0101] Co is a constant used to adjust whether the business recovery rate can dominate other weighted indicators.

[0102] r represents a reusable relay on the source node of link ij, which is in the same band as service k. For Reg of type work, only the corresponding service can use it.

[0103] R k This represents the set of relays that can be reused for service k, and the relays in this set are consistent with the original band of the service.

[0104] Indicates the total length or total number of hops of the link;

[0105] P indicates whether the total length used to adjust the new route for restoring services can dominate other weighted indicators;

[0106] Indicates the number of newly added relays;

[0107] M represents the indicator used to adjust whether the number of newly added relays can control other weighted indicators;

[0108] The superscript k represents the service index; h represents the h-th sub-path on the service path, and a sub-path represents an optical channel. All links on this optical channel have the same wavelength; irj represents a link ij that the service route passes through, and r represents the relay on node i; a=1 indicates that link ij is the first sub-path, a=0 indicates that it is not the first sub-path; b=1 indicates that the link sub-path is the last sub-path, b=0 indicates that it is not the last sub-path.

[0109] This indicates that repeaters should be used as little as possible;

[0110] N represents whether minimizing the number of multiplexed relays used can influence other weighted indicators.

[0111] Because ensuring maximum service recovery is always the top priority, the Co value needs to be larger than the maximum sum of P, M, and N. The above formula is a multi-objective function; adjusting different weights changes the final strategy. For example, to reduce the number of new relays, M can be set to 0.

[0112] Constraints (for the network e generated for each broken fiber link):

[0113] Source and destination node constraints:

[0114] This indicates that for all links (s,j) originating from the source point s of service k, only one satisfies the requirement;

[0115] In the formula, R k Let k be the set of relays that can be reused by service k, and the relays in this set are consistent with the original band of the service.

[0116] This indicates that only one link (i,d) from service k to destination node d satisfies the requirement.

[0117] Path connectivity constraints:

[0118] For each sub-path h of service k, it must be a link that connects the beginning and end. If the service passes through link (i,n), the next link must be (n,j), that is, the link that starts at n.

[0119] For the h-th sub-path and h+1 sub-path of business k, they must be links that are connected end to end. The last link of the h-th sub-path is (i,n), and the first link of the next sub-path h+1 must be the link (n,j) with n as the source node.

[0120] For all services to be restored, the number of services entering the h sub-path and the number of links leaving the h sub-path are the same for each h sub-path.

[0121] Anti-loop constraint

[0122] For a service to be restored, there can be at most one link entering the node n;

[0123] For a service to be restored, there can be at most one link with node n.

[0124] The two constraints above can ensure that a business process can only pass through one identical node at most.

[0125] Osnr constraints:

[0126] For C-band services, the OSNR attenuation value of C-band needs to meet the threshold requirements;

[0127] In the formula, Clf ij It is represented as the loss factor of link ij in the C-band.

[0128] For L-band services, the OSNR attenuation value of the L-band needs to meet the threshold requirements;

[0129] In the formula, Llf ij It is represented as the loss factor of link ij in the L band.

[0130] Since the reverse attenuation of the link may be inconsistent with the forward attenuation, the reverse OSNR threshold of the C wave is also constrained.

[0131] Since the reverse attenuation of the link may be inconsistent with the forward attenuation, the reverse OSNR threshold of the L-wave is also constrained.

[0132] The above four constraints indicate that the path of service k must meet the OSNR threshold requirement. If this requirement is not met, it is necessary to consider adding a relay in the middle.

[0133] Link wavelength constraints:

[0134] The number of services passing through each link is less than the number of channels that the link can support;

[0135] In the formula, W ij The set of available channels is represented by link ij.

[0136] The number of all C-band services passing through link (i,j) must be less than the number of C-channels on that link;

[0137] In the formula, K C Indicates the C-band service set;

[0138] W Cij This represents the set of available channels in the C-band on link ij.

[0139] The number of all L-band services passing through link (i,j) must be less than the number of L-channels on that link;

[0140] In the formula, K L Indicates the L-band service set;

[0141] W Lij It represents the set of available channels in the L-band on link ij.

[0142] Relay quantity constraints on nodes:

[0143] For a reusable relay r on node i, only services that originally occupied the relay before it failed can use it; other services awaiting recovery cannot use the relay.

[0144] For relays released by other services on node i, only the relay can be used by the node itself; other services cannot use the relay.

[0145] Alternatively, an exclusion constraint can be added in the first step. The exclusion problem is NP-hard in path planning, but in integer linear programming, it is a linear constraint.

[0146] Step 2: Allocate resources (local group, relay, wavelength) to the path calculated in Step 1.

[0147] Objective function:

[0148] In the formula, i represents the local group of the source node of path p, o represents the local group of the destination node of path p, and the variable includes two parts: 1. local group index; 2. existing relay index available for the service.

[0149] w represents the wavelength along this path;

[0150] k represents the kth business transaction;

[0151] p indicates that the non-looping paths calculated in the first step are sub-paths;

[0152] i = r means that node i uses relay r;

[0153] W k The set of channels that service k can use, considering that service k cannot use the original wavelength resources (local group, link) of other services, and the wavelength w used by service k. k w k ∈W k ;

[0154] The variable represents the source and destination ports of the p-th sub-path of the target service k when the wavelength of the io path is w. It is 1 if the condition is met and 0 if the condition is not met.

[0155] The variable represents the source and destination ports of the p-th sub-path of the target service k when the relay is r. It is 1 if the condition is met, and 0 if the condition is not met.

[0156] Source-sink constraint:

[0157] The above formula means that path p starts from node s and can only have one path or no path at all, and the number of paths cannot exceed 1. This means that business k can only have one path or no path starting from point s.

[0158] The above formula means that business k has only one path or no path back to point d.

[0159] Relay point constraints:

[0160] The above formula means that the service k has multiple sub-paths. The number of sub-paths m-1 and m-th are the same. In other words, the number of sub-paths m-1 and m-th are the same. If there is an m-1 sub-path but no m sub-path, then this path will be missing m sub-paths. Therefore, the sub-paths must be the same in number.

[0161] The above formula indicates that a relay is needed between multiple sub-paths. The relay is placed on two local groups, namely the o local group of sub-path m-1 and the i local group of sub-path m, both of which are relays r. A relay r consists of two local groups: an outgoing local group and an incoming local group.

[0162] The local groups at both ends of the relay cannot be the same:

[0163] Each relay can only be used once:

[0164] In the formula, W r This represents the set of channels that relay r can use.

[0165] Each relay can only use the wave available to that relay:

[0166] Each wavelength in the local group can only be used once:

[0167] Each wavelength in the link can only be used once (l:link):

[0168] Finally, by calling an integer linear programming solver, such as Cplex or Gurobi, the available paths for the services to be restored in the faulty network can be calculated, and the resources (local groups, relays, and wavelengths) of these paths are quantitatively satisfactory.

[0169] Example

[0170] As shown in Figure 2, a given optical transmission network has seven nodes: ABCDEFG, and eleven links: AB, AC, BD, BE, CD, CF, DE, EG, FG, DG1 (left side of Figure 2), and DG2 (right side of Figure 2). The number of available channels on each link is marked. The network topology is shown in the following figure, and the service matrix and the occupied path and link channel resources are as follows:

[0171] AE has 10 100G services, which are routed through ACDGE. The DG is DG1, and the services are s1-s. 10 1-10 waves;

[0172] DG has 10 100G service lines, which pass through DG1 and are denoted as service s. 11 -s 20 51-60 waves;

[0173] BG has 10 100G services, which pass through BDG, and DG is DG2. Let's denote the service as s. 21 -s 30 31-40 waves;

[0174] FB has 10 100G services. After passing through FGDB, DG is DG1, and the service is denoted as s. 31 -s 40 41-50 waves;

[0175] The steps are as follows:

[0176] (1) For the above network, there are 11 links. Forty services either pass through DG1 or DG2. When both DG1 and DG2 fail, all forty services need to be recalculated.

[0177] (2) Construct a model based on the objectives and constraints of the first step.

[0178] For the network above, P is set to 1, M to 500, N to 250, and Co to 1;

[0179] The first step in reconstructing the path, calculated using Gurobi, is as follows:

[0180] s1-s 10 The service recovery path is AC and CFGE, which are split into two segments, indicating that a relay needs to be added at point C.

[0181] s 11 -s 20 The service can be restored via the DEG path.

[0182] s 21 -s 30 The service recovery path is BD and DEG, which are split into two segments, indicating that a relay needs to be added at point D.

[0183] s 31 -s 40 The service recovery path is FGEB;

[0184] (3) The first step has already calculated the path. The second step is to allocate line ports, local groups, and trunks for the above path. The objective function for the second step is:

[0185] Here, the coefficient M is set to 4.

[0186] (4) Call Gurobi to calculate the resources for the path. The result of the second step is...

[0187] s1-s 10 The service recovery path is AC and CFGE, with AC channels 1-10 and CFGE channels 1-10.

[0188] s 10 -s 20 For the service, the recovery path is DEG, and the channels of DEG are 41-50;

[0189] s 21 -s 30 For the service, the recovery path is BD and DEG, with BD channel 31-40 and DEG channel 31-40;

[0190] s 31 -s 40 The service was restored via FGEB, with channels 76-80. Five services were restored, but the remaining five were lost.

[0191] As shown in Figure 3, this disclosure also proposes an OTN network service fault recovery system, the system comprising:

[0192] The first establishment module is used to establish a first objective function and set first constraints for the first objective function;

[0193] The first determining module is used to determine the available path for the service to be restored based on the first objective function;

[0194] The second establishment module is used to establish a second objective function based on the available paths of the service to be restored, and to set a second constraint condition for the second objective function;

[0195] The second determining module is used to determine the target path of the service to be restored based on the second objective function, and to perform fault recovery for the target path.

[0196] As shown in Figure 4, corresponding to the OTN network service fault recovery method provided above, this disclosure also provides an OTN network C+L optical layer service fault recovery device. Since the embodiment of this device is similar to the above method embodiment, the description is relatively simple. For relevant details, please refer to the description in the above method embodiment section. The device described below is merely illustrative. This device may include: a processor 1, a memory 2, a communication bus (i.e., the aforementioned device bus), and a lookup engine. The processor 1 and memory 2 communicate with each other through the communication bus and communicate with external systems through a communication interface. The processor 1 can call logical instructions in the memory 2 to execute the OTN network service fault recovery method.

[0197] Furthermore, the logical instructions in the aforementioned memory 2 can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this disclosure, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this disclosure. The aforementioned storage medium includes various media capable of storing program code, such as memory chips, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0198] On the other hand, this disclosure also provides a processor-readable storage medium storing a computer program 3, which, when executed by a processor 1, is implemented to perform the OTN network service fault recovery method provided in the above embodiments.

[0199] The processor-readable storage medium can be any available medium or data storage device that the processor 1 can access, including but not limited to magnetic memory (e.g., floppy disk, hard disk, magnetic tape, magneto-optical disk (MO)), optical memory (e.g., CD, DVD, BD, HVD), and semiconductor memory (e.g., ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)).

[0200] Those skilled in the art should understand that, despite the detailed description of this disclosure with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for recovering from OTN network service failures, characterized in that, The method includes: Establish a first objective function and set a first constraint condition for the first objective function; Based on the first objective function, determine the available paths for the services to be restored; A second objective function is established based on the available paths of the services to be restored, and a second constraint condition is set for the second objective function; Based on the second objective function, the target path of the service to be restored is determined, and fault recovery is performed on the target path.

2. The OTN network service fault recovery method according to claim 1, characterized in that, The establishment of the first objective function includes: Obtain path data in the faulty network; The path data is weighted and summed to obtain the first objective function.

3. The OTN network service fault recovery method according to claim 1, characterized in that, The path data in the faulty network includes: the number of services successfully restored in the faulty network, the total length or total number of links, the number of newly added relays, and the number of relays used that have been reduced.

4. The OTN network service fault recovery method according to claim 1, characterized in that, The first constraint includes: source and destination node constraints, path connectivity constraints, anti-loop constraints, OSNR constraints, link wavelength constraints, and the number of relays on the node.

5. The OTN network service fault recovery method according to claim 4, characterized in that, The source and destination node constraints include: only one link from the target source node to the target service meets the requirements; only one link from the target service to all destination nodes meets the requirements. The path connectivity constraints include: each sub-path of the target service is a link that connects end to end; the h-th sub-path and h+1-th sub-path of the target service are links that connect end to end; the number of services entering a sub-path is the same as the number of links exiting a sub-path. The anti-loop constraint includes: the number of links entering the target node is less than or equal to one; the number of links leaving the target node is less than or equal to one. The OSNR constraint includes: the OSNR attenuation values ​​of C-band and L-band in the target service meet the threshold requirements; The link wavelength constraints include: the number of services passing through each link is less than the number of channels that the link can support; the number of C-band services passing through the target link is less than the number of C-channels on the link; and the number of L-band services passing through the target link is less than the number of L-channels on the link. The constraints on the number of relays on the node include: the reusable relays on the target node can only be used for services that were originally occupied by the relays before the failure.

6. The OTN network service fault recovery method according to claim 1, characterized in that, After constructing the first constraint condition for the coefficients in the first objective function, the following is also included: Determine whether the coefficients in the first objective function satisfy the first constraint condition; If the condition is not met, a relay is added to the node.

7. The OTN network service fault recovery method according to claim 1, characterized in that, The establishment of the second objective function based on the available paths of the service to be restored includes: The variables are determined when the source and destination ports of the p-th sub-path of the target service are io paths with wavelength w, and when the source and destination ports of the p-th sub-path of the target service are r relays. The second objective function is obtained by weighting the variables when the source and destination ports of the p-th sub-path of the target service are r relays and summing them with the variables when the source and destination ports of the p-th sub-path of the target service are io paths with wavelength w.

8. The OTN network service fault recovery method according to claim 1, characterized in that, The second constraint includes: source-destination constraint, relay point constraint, local group constraint at both ends of the relay, relay constraint, available wavelength constraint of the relay, local group wavelength usage constraint, and link wavelength usage constraint.

9. The OTN network service fault recovery method according to claim 8, characterized in that, The source-destination constraints include: the target service has only one path or no path from the target point; the target service has only one path or no path back to the target point. The relay point constraints include: the number of m-1 sub-paths of the target service is the same as the number of m-th sub-paths; the o-local group of sub-path m-1 of the target service and the i-local group of sub-path m are the same relay. The local group constraints at both ends of the relay include: the local groups at both ends of the relay cannot be the same; The relay constraints include: each relay can only be used once; The wave constraints available to the relay include: each relay can only use the wave available to that relay; The local group wavelength usage constraints include: each wavelength in the local group can only be used once; The link wavelength usage constraints include: each wavelength can only be used once.

10. An OTN network service fault recovery system, characterized in that, The system includes: The first establishment module is used to establish a first objective function and set first constraints for the first objective function; The first determining module is used to determine the available path for the service to be restored based on the first objective function; The second establishment module is used to establish a second objective function based on the available paths of the service to be restored, and to set a second constraint condition for the second objective function; The second determining module is used to determine the target path of the service to be restored based on the second objective function, and to perform fault recovery for the target path.

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