CN105827528A - Routing method suitable for frequency spectrum-flexible optical network - Google Patents

Abstract

A routing method suitable for a frequency spectrum-flexible optical network includes the steps of: a. performing initialization configuration on a network; b. waiting for a service request to start; c. analyzing the type of the received service request, if the service request is a connection establishing request, entering the Step d, and if the service request is a connection releasing request, entering the Step h; d. starting route selection; e. judging whether a routing result is successful, if yes, entering the Step f, otherwise, entering the Step g; f. allocating frequency spectrum resources; g. searching a service chain table, and defining a process event of a next connection request; and h. releasing resources, and returning to the Step b. According to the routing method, in the routing process, selection and reforming of the frequency spectrum resources are performed, and allocation of the frequency spectrum resources is performed at the same time. The method adopts a heuristic algorithm, and has better flexibility than a traditional ILP method, does not need a central computational node, does not need global information, can completely adopt a distributed method to process, and is suitable for application to a large-scale network.

Description

A kind of route selection method being applicable to the flexible optical-fiber network of frequency spectrum

Technical field

The present invention relates to a kind of alternate routing system of selection being applicable to the flexible optical-fiber network of frequency spectrum, belong to communication technical field.

Background technology

Along with the service rate grade in optical-fiber network, business granularity are gradually increased, traditional network based on fixed wave length, fixing time slot cannot meet the explosive growth demand of business.Optical-fiber network is positioned to improve the level of resources utilization of network flexibly, to adapt to new service access.But, due to business dynamically tear down and build and service bandwidth lacks reasonably planning when being allocated, the running of network defines a large amount of scattered fragment, have impact on quickly accessing of follow-up Large Copacity business.When carrying out business route, it is necessary to take into account fragment risk that may be present, the route of business of making rational planning for, promote the access speed of business.The wavelength-division multiplex system (WavelengthDivisionMultiplexing is called for short WDM) of rasterizing is compared the wdm system without fixed-grid and cannot have been met current business demand.When considering business survivability, need to consider the multiple risks of network, all should account for when carrying out vocational work route, alternate routing selection.At present, planning and design for vocational work route consider more, and the resource consolidation for alternate routing considers less, thus cause Large Copacity business when breaking down, cannot quick-recovery soon, also need to the frequency spectrum resource of alternate routing is integrated in advance, waste the service recovery time of preciousness.Photographing On-line can be carried out by centralized webmaster in view of Work route, existing integral linear programming (IntegerLinearProgramming, it is called for short ILP) although method result of calculation more optimizes, but scene inapplicable is calculated in real time for dynamic business, it is impossible to meet the demand of quick router-level topology and resource distribution.On the other hand, the resource in flexible optical-fiber network, after fragmentation, can be shared by more business, but but has higher requirement calculating speed.Therefore, after backbone optical network business presents the obvious feature of mobilism, need to use a kind of heuritic approach that can reach to be similar to ILP performance.

Summary of the invention

Present invention aims to the drawback of prior art, a kind of route selection method being applicable to the flexible optical-fiber network of frequency spectrum is provided, to realize the fast resource calculating in large scale network, meet the demand of the quick router-level topology of dynamic business and resource distribution, enable the network to accommodate the higher business of bandwidth demand.

Problem of the present invention solves with following technical proposals:

A kind of route selection method being applicable to the flexible optical-fiber network of frequency spectrum, described Route Selection sequentially includes the following steps:

A. network being carried out initial configuration, configuration information includes: Network number, required frequency spectrum resource demand, the start-stop node location of business, enters step b after completing configuration；

B. latency services request starts, and for static traffic, takes out from the initial configuration chained list of network；For dynamic service, then dynamically start router-level topology according to the access request time of network, realize by the way of event triggers, after completing, enter step c；

C. analyze the type of received service request, if the information received is connection establishment request, then enter step d；If received message is connection release request, then enter step h；

D. start Route Selection, according to physical topology annexation, the resource limit condition of business, evaluation work route and alternate routing, after completing, enter step e；

E. judge that routing select result is the most successful, if the route calculated meets the qualifications in path and the restrictive condition of resource, then routing success, enter step f；Otherwise, routing unsuccessfully enters step g；

F. for the frequency spectrum resource on whole path, the frequency spectrum resource on the path of selected route is allocated, after completing, enters step g；

G. searching service chained list, the process event of the next connection request of definition, return step b；

H. resource release, returns step b.

The above-mentioned route selection method being applicable to the flexible optical-fiber network of frequency spectrum, the route computing method in described step d is as follows:

1. the business chained list that currently can obtain completely is inputted current topological structure, including at least source, the destination node of business, resource requirement, the node of network, the syntopy of link, after completing, enter step 2.；

2. the effective network topology structure of examination, eliminates invalid connection, enters step 3. after completing；

3. according to the weights on predefined all kinds of limit of traffic grooming policy definition, after completing, step is entered 4.；

4. start the excellent shortest path of K (KShortestPath is called for short KSP) routing, first construct the access point set between source-destination node, solve access route set, finally carry out path merging；

5. a plurality of route selected is carried out concordance judgement, i.e. the effectiveness selecting route is screened, determine whether selected route meets the access conditions of business, if all routes are the most undesirable, enter step 8.；Otherwise, step is entered 6.；

6. the route results screening route calculated according to KSP, analyzes the available bandwidth resources in the upper each of the links of business route, the link that bandwidth is minimum is defined as bottleneck link l, makes network reachWherein C_lAnd C_pRepresenting the link usable spectrum continuation degree on link l and path p respectively, L (p) is the link set constituting path p；

7. after completing Route Selection, update the topology of network, enter step 9.；

8. 9. statistical service failure number, enter step；

9. routing procedure terminates.

The above-mentioned route selection method being applicable to the flexible optical-fiber network of frequency spectrum, the link on described link l uses frequency spectrum continuation degree C_lCalculating, method is as follows:

$C_l=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l}{B_l}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^l}{F}$

Wherein, F is that each link circuit resource comprises frequency slot sum, B_lRepresent usable spectrum block number on link l,For the service condition of i-th frequency slot on link l,For the service condition of i+1 frequency slot on link l；

Usable spectrum block number B on link l_lEstimated by following formula:

$B_l=\underset{i=1}{\overset{F}{\Σ}}{u}_i^l-\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l;$

Link usable spectrum continuation degree C on described path p_pComputational methods as follows:

$C_p=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^p\·u_{i+1}^p}{B_p}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^p}{F}$

Wherein, For the spectrum occupancy state on the p of path,Estimate according to each link:

$u_i^p=\underset{l\∈L\left(p\right)}{min}\[u_i^{l_1},u_i^{l_2},\mathrm{...},u_i^{l_n}\]$

Wherein, l₁, l₂…l_nIt is respectively the n bar link on the p of path.

The present invention carries out selection and the reformation of frequency spectrum resource in routing procedure, is possible not only to the reduction business frequency spectrum fragment when routeing, and enables the network to accommodate the higher business of bandwidth demand, and is easy to follow-up bandwidth reallocation and management.The method carries out the distribution of frequency spectrum resource in routing procedure simultaneously, it is to avoid the rigid interruption of existing route, also reduces the demand for controlling plane and real time business cost in transmittance process simultaneously.The present invention uses heuritic approach, has more preferable motility than traditional ILP method, and without center calculation node, without global information, distributed method can be used completely to process, and is suitable to apply in large scale network.

Accompanying drawing explanation

Fig. 1 is the cross-connection point route resource method of salary distribution schematic diagram in flexible optical-fiber network；

Fig. 2 is router-level topology and the resource allocation flow figure of the present invention；

Fig. 3 is the flow chart of Route Selection and renewal.

Symbol: C used in literary composition_lAnd C_pRepresenting the link usable spectrum continuation degree on link l and path p respectively, L (p) is the link set constituting path p, and F is that each link circuit resource comprises frequency slot sum, B_lRepresent usable spectrum block number on link l,For the service condition of i-th frequency slot on link l,For the service condition of i+1 frequency slot on link l,For the spectrum occupancy state on the p of path, l₁, l₂…l_nIt is respectively the n bar link on the p of path.

Detailed description of the invention

The invention will be further described below in conjunction with the accompanying drawings.

The present invention proposes a kind of route selection method being applicable to the flexible optical-fiber network of frequency spectrum, the method is in the calculating and resource allocation process of alternate routing, first configuration Network number, required frequency spectrum resource demand, the start-stop node location information of business, business information is taken out from the initial configuration chained list of network for static traffic, for dynamic service then according to the access request time of network, dynamically start router-level topology, realize by the way of event triggers.Emphasis considers connection establishment request and the connection release request of business, in addition to evaluation work route, also provide for alternate routing to calculate simultaneously, calculating process mainly considers the physical topology annexation of business, resource limit condition, including the seriality restrictive condition etc. of distributed frequency spectrum, until whole business configuration alternate routings complete.

Its idiographic flow is described below in conjunction with the accompanying drawings.

Fig. 1 diagrammatically illustrates the cross-connection point route resource method of salary distribution in flexible optical-fiber network.In figure, Node1～Node6 respectively has the optical switch node of non-rasterizing resource management capacity.Wherein, there are two service paths being respectively the path between path A:Node1-Node3-Node4-Node6 Yu path B:Node2-Node3-Node4-Node5, Node3 and Node4 is common link, and two service paths are distinguished with thick line, fine rule respectively.On two service paths, the business accessed can be the business route after converging, can also be for the service connection initiated by path start node, the concrete business form is not construed as limiting the scope of this invention, the cross-coupled situation of more business may be there is at actual application scenarios, the method for the present invention can be used to analogize.Assuming that path A and path B resource requirement are respectively frequency spectrum resource A and frequency spectrum resource B, owing to two business routes exist public link, thus identical frequency spectrum resource cannot be used, must take into the resource limit of correspondence when carrying out business route.For high-speed optical transmission system, frequency spectrum resource A and frequency spectrum resource B should be reserved with protection bandwidth, to prevent from causing unnecessary crosstalk.In the flexible optical-fiber network of frequency spectrum, once the setting of business route completes, and each upstream and downstream node link in the paths all uses identical frequency spectrum resource, and for Large Copacity business, also needing to meet the adjacent constraints of frequency spectrum, the frequency spectrum resource one used is set to continuous dispensing.In the assigning process or removal process of frequency spectrum resource, once produce fragment, the access of follow-up business route will necessarily be affected, cause ineffective systems.Under conditions of meeting the restriction of frequency spectrum resource seriality, can effectively distribute and manage the resource of network.For there is no the business route of common link, common node, the most there is not the problem that frequency spectrum is overlapping, it is not necessary to account for.Consider compared with the technology of conventional optical network fixed-grid, the frequency spectrum resource in flexible optical-fiber network, can dynamically regulate untapped bandwidth and for other service channel.According to the bandwidth difference required for different time business, dynamically adjust the capacity of network, after discharging without resource, the fragment to bandwidth is integrated, and light path resource used can also be adjusted for the demand of user, thus reduces the risk of bandwidth inefficient assignment.It is no longer fixing owing to distributing to the resource of each connection, but is converted into a series of continuous print frequency spectrum, and width used does not the most determine, have to consider the seriality of resource during being allocated and managing.Static spectral resource allocation problem mathematically belongs to NP-Complete problem, is suitable only for mininet.When network size reaches to a certain degree, it is impossible to practical, particularly consider network have dynamic service connect tear down and build under conditions of, the recovery of network bandwidth surplus resources cannot set up accurate model, thus causes ILP method to apply.

Fig. 2 gives router-level topology and the resource allocation flow of the present invention:

In step a, network completes initial configuration, and the information configured includes: Network number, required frequency spectrum resource demand, the start-stop node location etc. of business, enters step b after completing to configure；

In step b, latency services request starts, and then takes out from the initial configuration chained list of network for static traffic；For dynamic service, owing to cannot accurately estimate the initiation time of dynamic requests, can dynamically start router-level topology according to the access request time of network, realize by the way of event triggers.After completing, enter step c；

In step c, analyzing the service request type received, content involved in the present invention is distributed with resource, therefore mainly for the router-level topology of business, only consider connection establishment request and the connection release request of business in step c, the process of other type of message is not construed as limiting the scope of this invention.If the information received is connection establishment request, then enter step d；If received message is connection release request, then enter step h；

In step d, starting Route Selection, this step is in addition to evaluation work route, also provide for alternate routing to calculate simultaneously, calculating process mainly considers the physical topology annexation of business, resource limit condition, such as the seriality restrictive condition etc. of frequency spectrum distribution, enters step e after completing；

In step e, it is judged that the routing select result of S204 is the most successful.If the route calculated meets the qualifications in path and the restriction of resource, then routing success, enter step f；Otherwise, routing unsuccessfully enters step g.

In step f, the frequency spectrum resource on the path of selected route is allocated, be different from routine distributed Route Selection, used by this step resource distribution time for the resource on whole path depending on, after completing enter step g.

In step g, searching service chained list, the process event of the next connection request of definition, return step b and wait request.If chained list is empty, then defined connection request is empty, the most still enters step b and waits dynamic service connection request next time.

In step h, resource discharges, and returns step b and waits request.

Fig. 3 gives the detailed process of the Route Selection described in step d and renewal；

In step 1., the business chained list that currently can obtain completely is inputted current topological structure, at least should comprise the source of business, destination node, resource requirement, the node of network, the syntopy etc. of link, after completing, enter step 2.；

In step 2., the effective network topology structure of examination, during this examination, main purpose is to eliminate invalid connection, although as some physical topology being unsatisfactory for resource requirement exists, if but add Resource Calculation, unnecessary calculating and storage resource will be expended.By effective examination, the calculating demand of real-time network can be reduced, improve response speed；

In step 3., according to the weights on predefined all kinds of limit of traffic grooming policy definition, after completing, step is entered 4.；Herein, depending on the setting of weights is primarily to adjust the business route of network, by traffic grooming strategy, different classes of business is ranged different routes, the most then can select different modulation formats according to the classification of business, transmit with the information of adaptive system transmitting-receiving node, also better profit from the fragment of frequency spectrum simultaneously.Compared with traditional fixed-grid network, the modulation format in original information transmittance process sets depending on needing according to light path used, then different according to the frequency spectrum used in optical-fiber network flexibly, is set for subcarrier.

In step 4., start the excellent shortest path of K (KShortestPath is called for short KSP) routing, first construct the access point set between source-destination node, solve access route set, finally carry out path merging.Meet topology resource successional under the conditions of, meet the uncorrelated principle in path, it is to avoid build and belong to the multirouting of same risk link group as far as possible；

In step 5., a plurality of route selected is carried out concordance judgement, mainly the effectiveness selecting route is screened at this, determine whether selected route meets the access conditions of business, if the result that step is 5. is empty set, namely all routes are the most undesirable, and progressive step is 8.；Otherwise, step is entered 6.；

In step 6., the route results calculated according to KSP, screening route, depending on the rule screened at this is mainly according to the frequency spectrum continuation degree of every paths, by comparing the usable spectrum continuation degree on link and path, the link that prioritizing selection differentiation is minimum.Assuming that the link usable spectrum continuation degree of link l and path p is respectively C_lAnd C_p, it is an object of the present invention to the route that on selected path, average link spectrum utilization degree difference is minimum, so that the utilization of resource more equalizes.

Determine that bottleneck link l makes network reachWherein C_lAnd C_pRepresenting the link usable spectrum continuation degree on link l and path p respectively, L (p) is the link set constituting path p.When being routed, need to consider the spectrum utilization situation of each of the links on every paths, be respectively directed to link l and path p and calculate C_lAnd C_p。

C_lComputational methods as follows:

$C_l=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l}{B_l}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^l}{F}$

Wherein, F is that each link circuit resource comprises frequency slot sum, B_lRepresent usable spectrum block number on link l,For the service condition of i-th frequency slot on link l,For the service condition of i+1 frequency slot on link l

On link l, usable spectrum block number is then estimated by following formula:

$B_l=\underset{i=1}{\overset{F}{\Σ}}{u}_i^l-\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l$

Spectrum occupancy state on the p of path then can be estimated according to each link:

$u_i^p=\underset{l\∈L\left(p\right)}{min}\[u_i^{l_1},u_i^{l_2},\mathrm{...},u_i^{l_n}\]$

Wherein, l₁, l₂…l_nIt is respectively the n bar link on the p of path, and then calculates the frequency spectrum continuation degree of path p；

$C_p=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^p\·u_{i+1}^p}{B_p}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^p}{F}$

Wherein,

In step 7., after completing Route Selection, update the topology of network, enter step 9.；

In step 8., statistical service failure number, enter step 9.；

In step 9., routing procedure terminates.

Above example is only in order to illustrate that technical scheme is not intended to limit; although the present invention being described in detail with reference to above-described embodiment; the detailed description of the invention of the present invention still can be modified or equivalent by those of ordinary skill in the field; these are without departing from any amendment of spirit and scope of the invention or equivalent, within the claims of the present invention all awaited the reply in application.

Claims (3)

1. being applicable to a route selection method for the flexible optical-fiber network of frequency spectrum, it is characterized in that, described Route Selection sequentially includes the following steps:

A. network being carried out initial configuration, configuration information includes: Network number, required frequency spectrum resource demand, the start-stop node location of business, enters step b after completing configuration；

B. latency services request starts, and for static traffic, takes out from the initial configuration chained list of network；For dynamic service, then dynamically start router-level topology according to the access request time of network, realize by the way of event triggers, after completing, enter step c；

C. analyze the type of received service request, if the information received is connection establishment request, then enter step d；If received message is connection release request, then enter step h；

D. start Route Selection, according to physical topology annexation, the resource limit condition of business, evaluation work route and alternate routing, after completing, enter step e；

E. judge that routing select result is the most successful, if the route calculated meets the qualifications in path and the restrictive condition of resource, then routing success, enter step f；Otherwise, routing unsuccessfully enters step g；

F. for the frequency spectrum resource on whole path, the frequency spectrum resource on the path of selected route is allocated, after completing, enters step g；

G. searching service chained list, the process event of the next connection request of definition, return step b；

H. resource release, returns step b.

The route selection method being applicable to the flexible optical-fiber network of frequency spectrum the most according to claim 1, is characterized in that, the route computing method in described step d is as follows:

1. the business chained list that currently can obtain completely is inputted current topological structure, including at least source, the destination node of business, resource requirement, the node of network, the syntopy of link, after completing, enter step 2.；

2. the effective network topology structure of examination, eliminates invalid connection, enters step 3. after completing；

3. according to the weights on predefined all kinds of limit of traffic grooming policy definition, after completing, step is entered 4.；

4. start the excellent shortest path of K (KShortestPath is called for short KSP) routing, first construct the access point set between source-destination node, solve access route set, finally carry out path merging；

5. a plurality of route selected is carried out concordance judgement, i.e. the effectiveness selecting route is screened, determine whether selected route meets the access conditions of business, if all routes are the most undesirable, enter step 8.；Otherwise, step is entered 6.；

6. the route results screening route calculated according to KSP, analyzes the available bandwidth resources in the upper each of the links of business route, the link that bandwidth is minimum is defined as bottleneck link l, makes network reachWherein C_lAnd C_pRepresenting the link usable spectrum continuation degree on link l and path p respectively, L (p) is the link set constituting path p；

7. after completing Route Selection, update the topology of network, enter step 9.；

8. 9. statistical service failure number, enter step；

9. routing procedure terminates.

The route selection method being applicable to the flexible optical-fiber network of frequency spectrum the most according to claim 2, is characterized in that, the link usable spectrum continuation degree C on described link l_lComputational methods as follows:

$C_l=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l}{B_l}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^l}{F}$

Wherein, F is that each link circuit resource comprises frequency slot sum, B_lRepresent usable spectrum block number on link l,For the service condition of i-th frequency slot on link l,For the service condition of i+1 frequency slot on link l；

Usable spectrum block number B on link l_lEstimated by following formula:

$B_l=\underset{i=1}{\overset{F}{\Σ}}{u}_i^l-\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^l\·u_{i+1}^l;$

Link usable spectrum continuation degree C on described path p_pComputational methods as follows:

$C_p=\frac{\underset{i=1}{\overset{F-1}{\Σ}}{u}_i^p\·u_{i+1}^p}{B_p}\×\frac{\underset{i=1}{\overset{F}{\Σ}}{u}_i^p}{F}$

Wherein, For the spectrum occupancy state on the p of path,Estimate according to each link:

$u_i^p=\underset{l\∈L\left(p\right)}{min}\[u_i^{l_1},u_i^{l_2},\mathrm{...},u_i^{l_n}\]$

Wherein, l₁, l₂…l_nIt is respectively the n bar link on the p of path.