CN103236982B - A kind of how point-to-multipoint smooth multicast route method based on multinuclear - Google Patents

Abstract

The present invention relates to multiple spot in a kind of optical-fiber network, to the routing problem of multicast, to propose structure multinuclear shared tree and solve how point-to-multipoint light multicast routing problem, realize minimizing wavelength and use number.Make all destination nodes add all shared trees, source node then adds a shared tree by link disjoint paths.Heuritic approach based on matrix selects epipole, ensures that each source node adds multicast tree, save wavelength channel like this when making epipole data minimum.For minimizing wavelength usage quantity further, in the structure shared tree stage, network code is adopted to find network code path.The method of the epipole system of selection that the present invention adopts and structure shared tree, is conducive to minimizing wavelength usage quantity, improves the wavelength resource utilance of optical multicast network, offered load is more balanced.

Description

A kind of how point-to-multipoint smooth multicast route method based on multinuclear

Technical field

The present invention relates to technical field of optical fiber communication, particularly relating to a kind of for solving how point-to-multipoint light multicast routing problem and the method for realization saving wavelength resource.

Technical background

Along with the rise of multicast application in optical-fiber network, the consumption of optical network band width increases rapidly, and this makes the multicast routing problem in optical-fiber network more and more be paid attention to.Divide with source node and destination node quantity, multicast can be divided into the multicast of point-to-multipoint, how point-to-multipoint multicast, how point-to-multipoint multicast.As everyone knows, need the information of transmission more, bandwidth consumed also can be more, so how point-to-multipoint multicast causes the extensive concern of researcher.

In optical-fiber network, set up a multicast request, be first exactly to be multicast request pathfinding, find the circuit that message transfer is walked.For point-to-multipoint multicast request, we need to set up a light tree and cover source node and all destination nodes, and all data that source node sends can be received by each destination node in success.And for how point-to-multipoint multicast request, have two kinds of solutions: active tree and shared tree.So-called active tree is exactly that how point-to-multipoint multicast request is regarded as multiple point-to-multipoint request, with each source node for root node sets up many multicast tree.In view of active tree is unfavorable for saving Internet resources, propose shared tree.Shared tree is divided into monokaryon shared tree and multinuclear shared tree, monokaryon shared tree only has an epipole, this epipole is responsible for the data that collection institute active node sends, be transmitted to all destination nodes again, in the multicast tree namely set up, institute's active node all will be connected in this epipole, is that the shared tree of root node covers all destination nodes with epipole.In multinuclear shared tree, multicast member can according to the concrete condition of self, as selected one of them core node to add with the condition such as position, time delay of epipole.Multicast protocol based on multi-core effectively can reduce bandwidth consumption, reduces link load.

2000, researcher Ahlswede proposes network code, network code is different from traditional routing and only simply copies forwarding operation, but add linear or non-linear encoding operation at intermediate node, multiple data can merge at intermediate node to be transmitted, finally carry out decode operation in destination node, obtain the data needed for destination node.Network code well can improve network throughput, and in optical-fiber network, also well can play the effect of saving wavelength resource.

The present invention proposes a kind of multicast route method how point-to-multipoint based on the realization of multi-core network coding shared tree, minimize and take wavelength resource.

Summary of the invention

For multiple spot in existing solution optical-fiber network to the method for Multicast routing problem, consume a large amount of wavelength resources, the present invention devises a kind of multinuclear shared tree building method of coding Network Based, and the method comprises: the method finding the shared tree of epipole and structure coding Network Based by the heuritic approach based on matrix.

The multinuclear shared tree building method of the coding Network Based that the present invention proposes specifically comprises: 1) find the alternative collection of epipole; 2) by the heuritic approach based on matrix in the alternative concentrated searching epipole of epipole; 3) coding path structure shared tree is found.

By abstract for optical-fiber network for scheming G (V, E, c, W), wherein, the set V of the node in optical-fiber network represents, optical fiber link set E between node represents, every bar limit e ∈ E corresponding cost c (e), a W represent the number of wavelengths that an optical fiber is supported.How point-to-multipoint multicast request is expressed as mp2mp (S, D), and wherein S is source node set, node set for the purpose of D.The transmission mode of shared tree is that source node identification must send destination node to again through epipole, if so source node appears between epipole to destination node, will there is circuitous path, makes the huge increasing of time delay.So alternative epipole collection first will be selected, make it not comprise such circuitous path.Suppose v _ifor epipole, to each alternative epipole v _i∈ V, finds the coding path of all destination nodes.If with v _icoding path on there is source node, at the alternative concentrated deletion of node v of epipole _i.

The present invention proposes a kind of method that how point-to-multipoint light Multicast Routing realizes minimizing wavelength use amount, it is characterized in that: to the arbitrary node in network, finds two the coding path Ps of this node to all destination nodes _code1, P _code2if, P _code1, P _code2in comprise any source node, in set of node, leave out this node, traveled through in set of node after all nodes, the set of node drawn is alternative epipole collection V, for alternative epipole concentrate arbitrary alternative epipole v _i, find the link disjoint paths between source node, and select epipole, in shared tree, source node adopts link disjoint paths to epipole part, adopts network code, the shared tree of constitution realization Multicast Routing in shared tree between epipole to destination node during information transmission.

Epipole is selected specifically to comprise, structure source node set covering theory M _v, matrix M _vmiddle element is that 1 expression is with v _ifor the shared tree of epipole can cover source node s _i, corresponding list shows alternative epipole, line display source node; Selection matrix M _vin comprise 1 maximum row, by the alternative epipole v corresponding to these row _iadd epipole collection, then delete the row corresponding to 1 in these row and this row, repeat aforesaid operations, until matrix M _vbecome empty matrix or full null matrix.Structure shared tree specifically comprises: the link disjoint paths from source node to epipole is added shared tree, first calculates Article 1 shortest path as Article 1 coding path with Dijktra shortest path first; Then two coding paths are searched for, search destination node d _ineighbor node v _x, and v _xnot at P _code1on.If v _xbe directly connected to another destination node d _jon, and be directly connected to P _code1on, directly return Article 2 coding path, wherein v _xfor coding nodes.If v _xbe not directly connected to another destination node d _jon, by intermediate node v _a, v _bv _cbe connected to d _jon, if v _xbe not directly connected to P _code1on, by intermediate node v _a, v _bv _cbe connected to P _code1on, return and comprise v _a, v _bv _carticle 2 coding path P _code2.

The how point-to-multipoint light multicast route method of the coding a kind of Network Based of the present invention's design, make all destination nodes add all shared trees, source node then adds a shared tree by link disjoint paths.Heuritic approach based on matrix selects epipole, ensures that institute's active node adds multicast tree, save wavelength channel like this when making epipole data minimum.For minimizing wavelength usage quantity further, in the structure shared tree stage, employing network code searching network code path, adds link disjoint and network code can well save wavelength usage quantity, improve the wavelength resource utilance of optical multicast network, improve the load balance of optical-fiber network.

Accompanying drawing explanation

Fig. 1 selects the alternative diversity method flow chart of epipole;

Fig. 2 is based on the flow chart of the heuritic approach selection epipole of matrix;

Fig. 3 constructs shared tree flow chart;

Fig. 4 multicast request Route Selection schematic diagram.

Embodiment

Construct shared tree most important be exactly epipole selection and build shared tree.When carrying out the selection of epipole, often cause high time delay, the series of problems such as high blocking rate, the selection of epipole is proved to be np hard problem, determines which or which epipole becomes an important problem.In optical-fiber network, when source node is more, selects an epipole, often cause and take huge wavelength channel number.So we select multiple epipole at this, structure multinuclear shared tree.The selection of epipole, based on the heuritic approach of matrix, selects minimum epipole to meet the covering covering institute's active node.

Need to meet in optical-fiber network: wavelength continuity and wavelength independence.Wavelength continuity refers to, in a light path, if there is not wavelength shifter, can only distribute same wavelength.Wavelength independence refers to, two different data are transmitted simultaneously on same optical fiber, and different wavelength can only be divided into avoid obscuring between data.

Therefore, in shared tree, epipole needs to collect the different pieces of information that not source node sends and sends destination node to again, if need the data that transmit a lot, at the link near epipole by the constraint of wavelength independence, can take a large amount of wavelength channels.So consider to use link disjoint paths from source node to epipole part, there is not one section of optical fiber like this and transmit multiple data, serve the effect of saving wavelength channel.But when source node number is a lot, an epipole may be selected can not to cover all source nodes with the path of link disjoint, and we need to select multiple epipole.Epipole to be selected exactly alternative the concentrating of epipole.Based on the heuritic approach of matrix, ensure to cover all source nodes by minimum epipole.The node of the alternative collection of each epipole is searched out to the link disjoint paths of source node, set up a source node set covering theory, in set covering theory, the alternative concentrated node of epipole is shown in each list, line display destination node, if with an alternative epipole node for epipole can cover a source node, position corresponding is in a matrix 1, otherwise is 0.First select to comprise 1 maximum row, namely select the epipole of energy cover-most source node, these row are deleted and deleted the row wherein corresponding to 1.At repetition aforesaid operations until matrix is empty matrix or full null matrix, just select to be over epipole.

If last matrix is empty matrix, shows that institute's active node can add in shared tree by the path of link disjoint, path is joined in shared tree.If selection epipole and in the process of puncture table matrix become full 0 matrix, show that not all source node can cover with link disjoint paths.

In structure shared tree, can not, with the source node of link disjoint paths route, select, from oneself nearest epipole, to be connected on shared tree with shortest path.Because network code can increase network throughput, use network code in shared tree epipole to destination node part, the throughput increasing network can reduce wavelength simultaneously and use number.To be that source at least exists the path of two link disjoint to destination node in the condition of destination node success decoded information, so propose the method for a kind of searching two link disjoint coding paths.First the shortest path of epipole to destination node is calculated as Article 1 coding path with Dijktra shortest path first; Next be the searching of Article 2 coding path, find the neighbor node of the destination node of current route to see and be directly connected in another destination node or link in another destination node by other nodes, see that this neighbor node directly links on Article 1 coding path or links on Article 1 coding path by intermediate node again, then return Article 2 coding path, specifically how to return and be illustrated at next one part accompanying drawing.

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

Fig. 1, for selecting the alternative collection flow chart of epipole, produces the alternative collection of epipole.First initialization, set of node, in optical-fiber network, all nodes set up set of node, to the arbitrary node in set of node, find two coding path P of this node to all destination nodes _code1, P _code2if, P _code1, P _code2in comprise any source node, just in set of node, leave out this node, traveled through in set of node after all nodes, the set of node drawn is alternative epipole collection corenode_candidateset=V, there is not any epipole that can produce circuitous path in set.

Concentrate in alternative epipole and select epipole, using number for saving wavelength, adopting link disjoint paths at source node to epipole part, ensure that every tree only uses a wavelength, but the source node that one tree covers may be a part of source node, so need to construct many shared trees.Adopt and complete selection to epipole based on the heuritic approach of matrix, select multiple epipole and ensure that minimum epipole quantity covers all source nodes.

For the arbitrary alternative epipole v that alternative epipole is concentrated _i, search out the link disjoint paths P between source node _linkdisjoint(v _i, s _i), s _irepresent source node.Structure source node set covering theory M _v, M _vmiddle element representation is with node v _ifor the shared tree of epipole covers source node s _irelation, wherein, use R _irepresent with epipole v _ithe set of source node can be covered, M _vbe that 1 expression is with v _ifor the shared tree of epipole can cover source node s _i, be 0 and represent with v _ifor the shared tree of epipole can not cover source node s _i.Corresponding epipole is shown in list in matrix, the source node that line display is corresponding.

By to matrix M _voperate and covered all source nodes with minimum epipole, first selected to comprise 1 maximum row, by the alternative epipole v corresponding to these row _iadd epipole to concentrate, then delete the row corresponding to 1 in these row and this row, the matrix continued deleting row and column carries out above-mentioned selection and deletion action, until matrix M _vbecome empty matrix or full null matrix, all epipoles all add epipole and concentrate, and complete the selection of epipole.

Accompanying drawing 2 is the flow process selecting epipole, comprises step:

Step1 initiation parameter, allows epipole collection corenode_set for empty;

There is any v in Step2 _i∈ corenode_candidateset, finds v _ito the link disjoint paths P of source node _linkdisjoint(v _i, s _i), if there is not v _i∈ corenode_candidateset, algorithm turns Step4;

Step3 is v _ileave out from corenode_candidateset, go to Step2;

Step4 calculates source node set covering theory M according to formula (1) _v, wherein R _irepresent with v _ifor the source node set that the shared tree of epipole covers.

Matrix(M _v)=(m) _{|S|×|corenode_candidateset|}

If Step5 is v _irow comprise 1 of maximum quantity;

Step6 is v _iadd epipole collection corenode_set;

Step7M _vin leave out v _irow corresponding to 1 in row and these row;

If Step8 is M _vbe not empty or full null matrix, go to Step5, if it is empty or full null matrix, select to terminate;

Accompanying drawing 3 is structure shared tree schematic diagram.Wherein, in shared tree, source node adopts link disjoint paths to epipole part, epipole adopts network code to destination node part, and the routing mode of network code is respectively the path that each destination node finds two link disjoint, this invention adopts a kind of coding strand path method of finding to construct shared tree.

Step1 adds shared tree the link disjoint paths from source node to epipole;

If Step2 set covering theory M _vfor full null matrix, in matrix, remain the s of 0 correspondence _ifor the source node that can not cover with link disjoint paths, s corresponding for complete zero this row _iwith shortest path by adding shared tree from oneself nearest epipole;

Step3 uses Dijkstra shortest path first to calculate epipole to destination node d _iarticle 1 coding path P _code1(s _i, d _i);

Step4 searches for Article 2 coding path: search destination node d _ineighbor node v _x, and v _xnot at P _code1on;

If Step5 is v _xbe directly connected to another destination node d _jon, and v _xbe directly connected to P _code1on, return Article 2 coding path, wherein, v _xfor coding nodes;

If Step6 is v _xbe not directly connected to another destination node d _jon, but by neighbor node v _a, v _bv _cbe connected to d _jon;

Step7v _xbe not directly connected to P _code1on, but by neighbor node v _a, v _bv _cbe connected to P _code1on;

Step8 returns and comprises v _a, v _bv _carticle 2 coding path P _code2;

Accompanying drawing 4 is a concrete example schematic diagram of this method.Fig. 4 (a) is network topology structure figure, and how point-to-multipoint multicast request is R ((s ₁, s ₂, s ₃), (d ₁, d ₂)), wherein, (s ₁, s ₂, s ₃) represent source node set, (d ₁, d ₂) for the purpose of node set, epipole alternative collection corenode_candidateset=[A, D, E].First to the source node that each alternative concentrated alternative epipole searching link disjoint paths can cover.Be that epipole shared tree can cover (s respectively with A, D, E ₁, s ₂, s ₃), (s ₁, s ₃), (s ₁, s ₃).According to the source node set covering theory that formula 1 constructs be:

$M_v=\begin{array}{cc}\begin{array}{c}{s}_1\\ s_2\\ s_3\end{array}& \stackrel{\begin{array}{ccc}A& D& E\end{array}}{\left[\begin{array}{ccc}1& 1& 1\\ 1& 0& 0\\ 1& 1& 1\end{array}\right]}\end{array}$

Because first row comprise quantity maximum 1, the node A of correspondence is added epipole and concentrates.Delete the row at 1 place in these row and this row, at this moment matrix M _vfor sky, complete the selection of epipole.I.e. corenode_set=[A].For the epipole structure shared tree selected.First link disjoint paths add epipole alternative concentrate, s ₁→ A, s ₂→ A, s ₃→ A.Then construct epipole to destination node part, with critical path method (CPM), destination node is added shared tree, as Article 1 coding path P _code1, to destination node d in Fig. 4 (a) ₁article 1 coding path be A → B → D → d ₁, to destination node d ₂article 1 coding path be A → C → F → d ₂.I is d ₁neighbor node, and I is not on Article 1 coding path, and I just in time links another destination node d ₂on, but it is not directly connected on Article 1 coding path, searches intermediate node, finds that I is connected on Article 1 coding path by intermediate node E, at this moment returns Article 2 coding path, for destination node d ₁for A → C → E → I → d ₁, destination node d ₂for A → B → E → I → d ₂, complete the structure of shared tree as shown in Fig. 4 (b).

This example only just can cover all destination nodes by an epipole, and the method selecting multiple epipole to construct shared tree is in a practical situation identical.

Claims (1)

1. light Multicast Routing point-to-multipoint more than realizes the method minimizing wavelength use amount, it is characterized in that: to the arbitrary node in set of node, finds two the coding path Ps of this node to all destination nodes _code1, P _code2if, P _code1, P _code2in comprise any source node, in set of node, leave out this node, traveled through in set of node after all nodes, the set of node drawn is alternative epipole collection V, for alternative epipole concentrate arbitrary alternative epipole v _i, find the link disjoint paths P between source node _linkdisjoint(v _i, s _i), s _irepresent source node, structure source node set covering theory M _v, M _vmiddle element representation is with node v _ifor the shared tree of epipole covers source node s _irelation, wherein, use R _irepresent with epipole v _ithe set of source node can be covered, M _vbe that 1 expression is with v _ifor the shared tree of epipole can cover source node s _i, be 0 and represent with v _ifor the shared tree of epipole can not cover source node s _i, corresponding epipole is shown in the list in matrix, the source node that line display is corresponding, by matrix M _voperate and covered all source nodes with minimum epipole, first selected to comprise 1 maximum row, by the alternative epipole v corresponding to these row _iadd epipole to concentrate, then delete the row corresponding to 1 in these row and this row, the matrix continued deleting row and column carries out above-mentioned selection and deletion action, until matrix M _vbecome empty matrix or full null matrix, all epipoles all add epipole and concentrate, and complete the selection of epipole; Link disjoint paths from source node to epipole is added shared tree, first calculates Article 1 shortest path as Article 1 coding path with shortest path first; Search destination node d _ineighbor node v _x, and v _xnot at P _code1on; If v _xbe not directly connected to another destination node d _jon, find intermediate node to be connected to d _jon; If v _xbe not directly connected to P _code1on, find intermediate node to be connected to P _code1on; If v _xbe directly connected to P _code1on, return Article 2 coding path P _code2, be epipole structure shared tree.