CN105007223A - Optical network dynamic multicast routing wavelength allocation method based on optical hierarchical structure - Google Patents

Abstract

The invention discloses an optical network dynamic multicast routing wavelength allocation method based on an optical hierarchical structure. According to the method, an improved Edge Removal Light-Hierarchy (ERLH) algorithm is introduced into optical network dynamic multicast routing wavelength allocation; when a destination node is selected and a corresponding shortest path is added in an optical hierarchy, the cost of the path, quantity of surplus wavelength in the path and quantity of surplus wavelength of the whole network are considered comprehensively; according to the occupation situation of current resources of the network, the path is selected dynamically; and a new weight setting manner and a new dynamic regulation routing strategy are further proposed, so that the path added in the optical hierarchy is distributed in the path with the shortest distance, smallest load and largest ratio of the quantity of surplus wavelength to the cost, the network resource is fully reasonably used, and the blocking rate of the optical network is lowered.

Description

A kind of optical-fiber network dynamic multicast routing Wavelength allocation method based on photosphere time framework

Technical field

The present invention relates to a kind of optical-fiber network dynamic multicast routing and Wavelength allocation method, particularly relate to a kind of optical-fiber network dynamic multicast routing based on photosphere time framework and Wavelength allocation method, belong to technical field of photo communication.

Background technology

Optical-fiber network is made up of the multi-wavelength optical fiber link of network node and connected node.Wavelength-division multiplex technique (WDM) can transmit the light signal of some different wave lengths in an optical fiber simultaneously, and the scheme that possesses skills is ripe and be easy to the features such as expansion, is to make full use of one of fiber bandwidth and the most frequently used method of capacity at present.

Route symmetry (RWA) is one of key problem of design and optimization in WDM optical-fiber network, mainly refers to for the connection request from source node to destination node selects suitable route in optical-fiber network, and gives the wavelength that this route assignment is suitable.Multicast is a kind of point-to-multipoint communication mode, and the point-to-multipoint wavelength channel set up in optical-fiber network is called that light is set, and namely the multicast RWA problem in WDM optical-fiber network sets up point-to-multipoint light tree.In full light splitting WDM network, all nodes all can light splitting, sets up a multicast conversation and only needs a light tree, be called Steiner problem.Compared with common RWA problem, set up existence in multicast tree optical-fiber network and comprise the restricted problems such as sparse splitting device configuration constraint, wavelength continuity constraint, Energy Damage constraint.Because optical splitter is expensive, and can excess loss be brought, wavelength convert also can introduce extra cost, and technology realizes relative complex, and the multicast RWA problem therefore studied in the WDM optical-fiber network under the configuration of sparse splitting device and the configuration of zero wavelength shifter has better using value.In WDM optical-fiber network under sparse splitting device configuration constraint and wavelength continuity configuration constraint, RWA algorithm comprises the source of being re-routed to, is re-routed to any node, only for member, member's priority scheduling.Pertinent literature shows: in above four kinds of classic algorithm, member's priority algorithm controls blocking rate preferably, combination property optimum [Xijun Zhang, John Wei, Chunming Qiao.Constrained MulticastRouting in WDM Networks with Sparse Light Splitting [J] .IEEE/OSA Journal of LightwareTechnology, 2000:18 (12): 1917-1927].

WDM network under sparse splitting configuration can regard a non-directed graph G (V, E, c, W) as.The fixed-point set of V representative graph G.Each node v ∈ V, v are MI node (can not multicast node) or MC node (can multicast node).

V＝{v|v＝MI or v＝MC} (4)

The limit collection of E representative graph G, corresponding with the optical fiber link between nodes.W represents the number of wavelengths that every root optical fiber is supported.Every bar limit e ∈ E associates cost function C (e).Because target is the use minimizing wavelength channel, therefore cost function C (e) can be defined as follows:

C(e)＝1,e∈E (5)

Consider a multicast conversation ms (s, D), and following restriction should be met: (1) Wavelength continuity constraint, namely under the condition not having wavelength shifter, all links of a light framework (such as light tree or photosphere) must use identical wavelength; (2) discriminate among wavelengths restriction, if two light trees have intersects, must use different wavelength; (3) sparse splitting restriction.A set (such as light tree) completed from source s to the light framework of the multicast conversation of all destination node set D is set up in request.Without loss of generality, suppose in a multicast conversation, have K=|D| destination node, setting up this multicast conversation ms (s, D) needs k light framework (such as light tree or photosphere) LS _i(s, D _i), wherein i ∈ [1, k], 1≤k≤K≤N-1.Consider the optimum utilization of Internet resources, total cost should be minimum.Therefore, a multicast conversation total cost can by set up this multicast conversation all smooth framework cost and calculate

$C\left(ms\left(s,D\right)\right)=\underset{i=1}{\overset{k}{\Σ}}C\left({\mathrm{LT}}_i\right)=\underset{i=1}{\overset{k}{\Σ}}\underset{e\∈{\mathrm{LT}}_i}{\Σ}C\left(e\right)=\underset{i=1}{\overset{k}{\Σ}}\underset{e\∈{\mathrm{LT}}_i}{\Σ}1---\left(6\right)$

In the WDM optical-fiber network of sparse splitting configuration, because MI node can not as branch node, therefore light tree framework is considered to make full use of the preferred plan that namely wavelength channel number minimizes total cost.Intersect to the appearance of switch (CPS) make number of degrees be more than or equal to 4 node can accessed twice.By utilizing different input/output ports pair, 4 degree of MI nodes can connect two inherit nodes in a light framework.Intersect to exchange to realize, this MI node also should connect two predecessor node simultaneously.Such 4 degree of MI nodes energy accessed twice, multicast framework will be no longer light tree, but photosphere, because ring may be had to exist.

Consider a multicast conversation ms (s, D), in photosphere time, because a MI node may be traversed twice, and in subhierarchy with the limit crossed can not be used in same photosphere secondary in.Therefore, when setting up the photosphere time of multicast conversation, the limit used in subhierarchy is useless for the remaining destination node of traversal.Light hierarchical algorithms can be eliminated with limit and calculate photosphere: be and calculate photosphere, find out in each iteration and current photosphere time LH _knearest destination node d _i, will G be schemed _iin this shortest path (d _i, c _i) join current photosphere time LH _k(c _ifor d _iwith the Best link point that current photosphere is secondary); Then by shortest path (d _i, c _i) in limit from figure G _imiddle deletion generates new figure G _i+1, upgrade MC_SET (figure G simultaneously _ithe set of middle MC node).In next iteration, calculating chart G _i+1in shortest path and find out the destination node time nearest with current photosphere.Owing to being sparse splitting configuration, similar light tree framework, a multicast conversation may need to set up multiple photosphere.Due to the use intersected to switch, make accessed twice of 4 degree of MI nodes possibility, verified in sparse splitting configuration network, photosphere time multicast framework more can make full use of wavelength channel [Fen Zhou than light tree multicast framework, Miklos Molnar, Bernard Cousin.Is Light-tree Structure Optimalfor Multicast Routing in Sparse Light Splitting WDM Networks [J], In Proc.18thInternational Conference on Computer Communications and Networks, San Francisco, USA, 2009.].Therefore, photosphere time multicast framework is the best QoS routing scheme in sparse splitting network.

Traditional limit is eliminated in light hierarchical algorithms, always selects each time from the secondary nearest destination node of current photosphere, and the shortest path of correspondence is added this photosphere during iteration.Select the cost that only considered path during nearest destination node, cause the cost in some path of later stage may not be minimum, but wavelength resource is very abundant, assignable wavelength may not be there is in some shortest path, but still select this link to add photosphere, thus produce the waste of link congestion and wavelength resource.Therefore, if eliminate light hierarchical algorithms with limit to solve RWA problem, needing to eliminate light hierarchical algorithms for traditional limit to improve, when selecting destination node and corresponding shortest path is added photosphere time, the cost in path and path medium wavelength resource being taken into account as constraint simultaneously.

Summary of the invention

Technical problem to be solved by this invention is, for introducing overcome limit eliminate light hierarchical algorithms set up photosphere solve RWA problem time, produce the waste of link congestion and wavelength resource owing to not considering wavelength resource in link, propose a kind of optical-fiber network dynamic multicast routing based on photosphere time framework and Wavelength allocation method.

Thinking of the present invention is in the secondary nearest destination node of chosen distance photosphere, and when the shortest path of its correspondence being added photosphere time, not only the path of Least-cost is added photosphere time [Fen Zhou, Molnar, M., Cousin, B.Light-Hierarchy:Cost-Efficient Structure for Multicast Routing in WDM Mesh Networks [J], Computers and Communications (ISCC), DOL 10, 2010, pp.611-616], but consider the residue wavelength sum remaining number of wavelengths and the whole network in the cost in path and path, and new weight setting mode is proposed.Dynamically can regulate routing policy accordingly: increase when wavelength resource remaining in network comparatively enriches and select the probability of shortest path, remain in network number of wavelengths less time increase in selecting paths and remain the large probability of number of wavelengths.The maximum path of the value calculated by new weighting function adds photosphere, and the path profile making to add this photosphere time is the shortest in distance, on least-loaded and residue number of wavelengths and the maximum path of cost ratio.

Traditional limit is eliminated light hierarchical algorithms and is adopted formula (7) to calculate when selecting paths adds photosphere time:

$C\left({\mathrm{SP}}_{G_i}\right(d_i,c_i\left)\right)\underset{d\∈D,c\∈MC\_SET}{\min }C\left({\mathrm{SP}}_{G_i}\right(d,c\left)\right)---\left(7\right)$

In formula, function C () is path cost.The present invention eliminates on light hierarchical algorithms (ERLH) basis on limit to improve, and specifically, the present invention takes following technical scheme:

Utilize limit to eliminate light hierarchical algorithms and carry out QoS routing and Wavelength Assignment, adopt formula (1) to calculate when selecting paths adds photosphere time:

$P\left({\mathrm{SP}}_{G_i}\right(d_i,c_i\left)\right)=\underset{d\∈D,c\∈MC\_SET}{max}P\left({\mathrm{SP}}_{G_i}\right(d,c\left)\right)---\left(1\right)$

In formula, D represents the set of destination node, and MC_SET represents the topological diagram G after upgrading for i-th time _ithe set of middle MC node, (d, c) represents the shortest path of c to d, and wherein P () is weighting function, and it is expressed as follows:

$P\left({\mathrm{SP}}_{G_i}\right(d,c))=N_w/N_c^{\mathrm{\α}}---\left(2\right)$

In formula, represent path cost, N _cthe jumping figure of larger explanation path process is more, N _cthe jumping figure of less explanation path process is fewer; N _wrepresent the residue number of wavelengths in path, i.e. the least residue number of wavelengths of each section of link on path, N _wremain number of wavelengths in larger expression network more, namely the degree of crowding in path is less; If N _wwavelength resource is remained fewer in less expression network.α is factor of influence, and it determines by remaining wavelength sum in whole network, by changing the value of α, just can realize different routing policies, choosing different routes.

When selecting paths adds photosphere time, the routing policy that light hierarchical algorithms is eliminated on the limit that the present invention improves is when remaining wavelength sum in network and being larger, the selection of short path should be increased, namely should be increased the wavelength channel number N in path in weighting function P () by adjustment α _cimpact; When remaining wavelength sum in network and being less, the selection of little loaded link should be increased, namely should increase residue number of wavelengths N in path in weighting function P () by adjustment α _wimpact.Internet resources can be utilized fully like this, reasonably allocation of network resources, not be only carry out Route Selection according to the cost in path or residue number of wavelengths, reduce network blocking probability.

Provide the setting of α below:

α=9.8R _w+ 0.2 0≤R _wr in≤1 (3) formula _wthe residue wavelength rate of network, R _wequal the ratio remaining number of wavelengths and the total number of wavelengths of network in network.Factor of influence α is set to the residue wavelength rate R about network _wcontinuous function, routing policy can be regulated real-time dynamicly according to remaining in network number of wavelengths.

The framework of algorithm is as follows:

Dijkstra's algorithm 1-1) is utilized to calculate the shortest path of all d ∈ D to c ∈ MC_SET according to the ratio R remaining number of wavelengths and the total number of wavelengths of network in network _wcalculate α value by formula (3), then calculate path by formula (2) weight, calculate optimal path finally by formula (1) and add photosphere time, if more than one of the optimum light path calculated, then select that paths had from the nearest tie point of source node s;

1-2) by 1-1) the destination node d of optimum light path that selects _iremove from D, the MC node in destination node and optimum light path is added MC_SET, if tie point c _ithat MI node is then removed, finally 1-1 from MC_SET) link in the optimum light path selected is from figure G _imiddle removal;

If 1-3) there is destination node can be connected to current photosphere time, i ← i+1 redirect 1-1), otherwise, redirect 1-4);

1-4) to photosphere time LH _kdistribute wavelength;

If 1-5) destination node D is empty set, then multicast conversation is set up complete, otherwise k ← k+1, i ← 1 is redirect 1-1 also).

The limit of improving is eliminated in light hierarchical algorithms (ERLH algorithm) dynamic multicast routing of introducing optical-fiber network and Wavelength Assignment, when selecting destination node and corresponding shortest path is added photosphere time, consider the residue wavelength sum remaining number of wavelengths and the whole network in the cost in path and path, according to network condition dynamically selecting paths; The weight setting mode that further proposition is new, dynamic adjustments routing policy, by the path profile that adds photosphere time in the shortest, least-loaded and residue number of wavelengths and the maximum path of cost ratio, with abundant Appropriate application Internet resources, reduce the blocking rate of optical-fiber network.

Accompanying drawing explanation

Fig. 1 is the flow chart of optical-fiber network dynamic multicast routing Wavelength allocation method of the present invention.

Embodiment

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in detail.

Fig. 1 is the flow chart of this optical-fiber network dynamic multicast routing Wavelength allocation method, utilizes limit to eliminate light hierarchical algorithms and carries out QoS routing and Wavelength Assignment, adopt formula (1) to calculate when selecting paths adds photosphere time:

$P\left({\mathrm{SP}}_{G_i}\right(d_i,c_i\left)\right)=\underset{d\∈D,c\∈MC\_SET}{max}P\left({\mathrm{SP}}_{G_i}\right(d,c\left)\right)---\left(1\right)$

In formula, D represents the set of destination node, and MC_SET represents the topological diagram G after upgrading for i-th time _ithe set of middle MC node, represent the shortest path of c to d, wherein P () is weighting function, and it is expressed as follows:

$P\left({\mathrm{SP}}_{G_i}\right(d,c))=N_w/N_c^{\mathrm{\α}}---\left(2\right)$

In formula, represent path cost, N _cthe jumping figure of larger explanation path process is more, N _cthe jumping figure of less explanation path process is fewer; N _wrepresent the residue number of wavelengths in path, i.e. the least residue number of wavelengths of each section of link on path, N _wremain number of wavelengths in larger expression network more, namely the degree of crowding in path is less; If N _wwavelength resource is remained fewer in less expression network.α is factor of influence, and it determines by remaining wavelength sum in whole network, by changing the value of α, just can realize different routing policies, choosing different routes.

When selecting paths adds photosphere time, when remaining wavelength sum in network and being larger by the routing policy that light hierarchical algorithms is eliminated on the limit of improvement, the selection of short path should be increased, namely should be increased the wavelength channel number N in path in weighting function P () by adjustment α _cimpact; When remaining wavelength sum in network and being less, the selection of little loaded link should be increased, namely should increase residue number of wavelengths N in path in weighting function P () by adjustment α _wimpact.Internet resources can be utilized fully like this, reasonably allocation of network resources, not be only carry out Route Selection according to the cost in path or residue number of wavelengths, reduce network blocking probability.

Provide the setting of α below:

α＝9.8R _w+0.2 0≤R _w≤1 (3)

R in formula _wthe residue wavelength rate of network, R _wequal the ratio remaining number of wavelengths and the total number of wavelengths of network in network.Factor of influence α is set to the residue wavelength rate R about network _wcontinuous function, routing policy can be regulated real-time dynamicly according to remaining in network number of wavelengths.

If consider multicast conversation ms (s, D ₀), the specific implementation step of this QoS routing and Wavelength allocation method is as follows:

Step1: initialization network, arranges all wavelengths channel and is idle condition;

Step2: judged whether that business arrives, if having, redirect Step3, if not, continues to wait for;

Step3: multicast service initialization, k ← 1, D ← D ₀;

Step4: initialization photosphere time LH _k={ s}, figure G _i← G, MC_SET ← { s};

Step5: utilize dijkstra's algorithm to calculate the shortest path of all d ∈ D to c ∈ MC_SET according to the ratio R remaining number of wavelengths and the total number of wavelengths of network in network _wcalculate α value by formula (3), then calculate path by formula (2) weight, calculate optimal path finally by formula (1) and add photosphere time, if more than one of the optimum light path calculated, then select that paths had from the nearest tie point of source node s;

Step6: the destination node d of the optimum light path that Step5 is selected _iremove from D, the MC node in destination node and optimum light path is added MC_SET, if tie point c _ibe that MI node is then removed from MC_SET, the link in the optimum light path finally Step5 selected is from figure G _imiddle removal;

Step7: judged whether that destination node can be connected to current photosphere time, if having, i ← i+1 redirect Step5, if not, redirect Step8;

Step8: to photosphere time LH _kdistribute wavelength;

Step9: if destination node D is empty set, then multicast conversation is set up complete, otherwise k ← k+1, i ← 1 is redirect Step4 also.

Claims (1)

1. based on an optical-fiber network dynamic multicast routing Wavelength allocation method for photosphere time framework, it is characterized in that, utilize limit to eliminate light hierarchical algorithms and carry out QoS routing and Wavelength Assignment, adopt formula (1) to calculate when selecting paths adds photosphere time:

$P\left({\mathrm{SP}}_{G_i}\right(d_i,c_i\left)\right)=\underset{d\∈D,c\∈MC\_SET}{\max }P\left({\mathrm{SP}}_{G_i}\right(d,c\left)\right)---\left(1\right)$

In formula, D represents the set of destination node, and MC_SET represents the topological diagram G after upgrading for i-th time _ithe set of middle MC node, represent the shortest path of c to d, wherein P () is weighting function, and it is expressed as follows:

$P\left({\mathrm{SP}}_{G_i}\right(d,c))=N_w/N_c^{\mathrm{\α}}---\left(2\right)$

In formula, represent path cost, N _cthe jumping figure of larger explanation path process is more, N _cthe jumping figure of less explanation path process is fewer, and path is shorter; N _wrepresent the residue number of wavelengths in path, i.e. the least residue number of wavelengths of each section of link on path, N _wremain number of wavelengths in larger expression network more, namely the degree of crowding in path is less; If N _wless, remain wavelength resource in expression network fewer; α is factor of influence, determining, by changing the value of α, just can realize different routing policies, choosing different routes by remaining wavelength sum in whole network; α value sets factor of influence in the following way:

α＝9.8R _w+0.2 0≤R _w≤1 (3)

R in formula _wthe residue wavelength rate of network, R _wequal the ratio remaining number of wavelengths and the total number of wavelengths of network in network.Factor of influence α is set to the residue wavelength rate R about network _wcontinuous function, routing policy can be regulated real-time dynamicly according to remaining in network number of wavelengths;

The framework of algorithm is as follows:

Dijkstra's algorithm 1-1) is utilized to calculate the shortest path of all d ∈ D to c ∈ MC_SET according to the ratio R remaining number of wavelengths and the total number of wavelengths of network in network _wcalculate α value by formula (3), then calculate path by formula (2) weight, calculate optimal path finally by formula (1) and add photosphere time, if more than one of the optimum light path calculated, then select that paths had from the nearest tie point of source node s;

1-2) by 1-1) the destination node d of optimum light path that selects _iremove from D, the MC node in destination node and optimum light path is added MC_SET, if tie point c _ithat MI node is then removed, finally 1-1 from MC_SET) link in the optimum light path selected is from figure G _imiddle removal;

If 1-3) there is destination node can be connected to current photosphere time, i ← i+1 redirect 1-1), otherwise, redirect 1-4);

1-4) to photosphere time LH _kdistribute wavelength;

If 1-5) destination node D is empty set, then multicast conversation is set up complete, otherwise k ← k+1, i ← 1 is redirect 1-1 also).