CN108809834B - Network topology dispersed short path set calculation method based on path expansion and elimination mechanism - Google Patents

Abstract

The invention provides a network topology dispersed short-path set calculation method based on a path expansion and elimination mechanism, which comprises the following steps when calculating a topology dispersed short-path set from any node o to another node d in a network: traversing each neighbor node j of o, and adding a direct path o → j from o to j into empty sets omega and S_o,j(ii) a If omega is empty, return to S_o,dOtherwise, circularly taking a path P with the shortest length from omega and traversing each neighbor node t of a tail node S of P, if t does not appear in P, expanding to generate a path P → t from o to t, and adding the path into S when the length of P → t does not exceed the length upper limit_o,tIf added, S_o,tEliminating S by combining the concept of node topology overlapping cost when the number of included paths exceeds the specified upper limit_o,tThe other path except the path with the shortest length is topologically overlapped with the other path with the largest overlap.

Description

Network topology dispersed short path set calculation method based on path expansion and elimination mechanism

Technical Field

The invention relates to the field of transmission and routing networks, in particular to a network topology dispersed short path set calculation method based on a path expansion and elimination mechanism.

Background

Various transmission networks, such as urban road networks, computer communication networks and the like, are common in modern society and are important infrastructures for supporting social operations. When these networks are operated, the transmission object starts from the starting node and arrives at the destination node along a path, and the path is often given by a certain network routing algorithm operation. The efficient network routing algorithm can ensure that the transmission objects can avoid traffic jam areas in the network as much as possible in the transmission process, the transmission is completed quickly, and the network is not easy to jam.

Currently, a common network routing algorithm usually adopts a shortest path routing idea, that is, a transport object is specified to be transmitted along a path with the shortest length from a starting node to a destination node. Shortest path routing is simple to implement, but network congestion cannot be relieved well when network traffic flow is large, because from the perspective of network topology, shortest paths between different node pairs of a network generally pass through a small number of core nodes in the network, and the nodes can become traffic bottleneck nodes when the network applies shortest path routing.

It should be noted that a large number of ring subgraphs often exist in a common transmission network, that is, a plurality of paths with dispersed topology (that is, the same nodes or connecting edges passed by each path are fewer) and shorter length (that is, the length of each path is close to the length of the shortest path) may exist between a pair of nodes in the network, and the set formed by the paths is called as a topology dispersed short path set of the pair of nodes. If the transmission objects with the same initial destination node pair are transmitted along different paths in the topology dispersed short path set from the initial node to the destination node in a time-sharing manner according to the actual network traffic condition in the network routing and transmission process, the probability that the transmission objects avoid the network traffic jam area can be effectively increased, the load balance distribution of the network is realized, and the transmission performance of the network is improved.

The calculation method of the network topology decentralized short path set is a key basis of the routing idea. The invention provides a novel network topology dispersed short path set calculation method based on a path expansion and elimination mechanism.

Disclosure of Invention

The invention provides a network topology dispersed short-path set calculation method based on a path expansion and elimination mechanism, which comprises the following steps when calculating a topology dispersed short-path set from any node o to another node d in a network:

step 1: an empty path set omega is created, and an empty path set S is created for each node i except the node o in the network_o,iAnd a variable l with a value of positive infinity_o,iWherein l is_o,iFor storing sets S_o,iLength of the shortest path in (1);

step 2: traversing each neighbor node j of the node o, and simultaneously adding the direct path o → j from the node o to the node j into omega and S_o,j；

And step 3: if omega is empty, jumping to step 6;

and 4, step 4: taking out a path P with the shortest length from the omega and removing the path P from the omega; and then traversing each neighbor node t of the node s for the tail node s of the path P, and if the node t does not appear in the path P, executing the operations of the steps 4.1-4.4:

step 4.1: expanding the path P by using the node t to obtain a path P → t;

step 4.2: if the length of the path P → t is less than l_o,t×α, the path P → t is added to S_o,tSimultaneously update l_o,tIs S_o,tLength of the shortest path in (1); then delete S_o,tAll lengths in are greater than l_o,t×α;

step 4.3: if S_o,tComprising β +1 paths, then first for each node k in the network, statistics S_o,tHow many paths pass through the node k is called the topology overlapping cost of the node k; then from S_o,tEliminating another path except the path with the shortest length, wherein the sum of topology overlapping costs of all nodes passing through the path is the largest;

step 4.4: if the path P → t exists in S_o,tIn, the path P → t is added to Ω.

And 5: skipping to the step 3;

step 6: when the operation is finished, return to S_o,dAs a topological dispersed short path set from node o to node d.

In the above step, the length of the path is defined as the number of nodes through which the path passes, α is an adjustable parameter for controlling an upper limit of the length of the path in the topology distributed short-path set, and a value of α is greater than 1.0, and β is an adjustable parameter for controlling an upper limit of the number of paths in the topology distributed short-path set, and a value of β is greater than or equal to 1.

The technical conception of the invention is as follows: and expanding and generating a path P → t from the node o to a neighbor node t of the node s by utilizing a path P in the calculated topological dispersed path set from the starting node o to the node s, adding the path into the topological dispersed path set from the node o to the node t when the path length is short, and otherwise, eliminating the path. Meanwhile, when the number of paths contained in the topology dispersion path set exceeds the upper limit, the concept of node topology overlapping cost is combined, and another path which is topologically overlapped with other paths and has the maximum length except the path with the shortest length is eliminated.

The invention has the beneficial effects that: the given calculation method can effectively calculate the topology dispersed short path set of any pair of nodes in the network. Meanwhile, the given calculation method can calculate the topology dispersed short path set from one starting node to all other nodes in the network at one time, and the calculation time consumed by sharing the topology dispersed short path set to one pair of nodes is less.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention and not to limit the present invention. In the drawings, FIG. 1 illustrates a network topology of one embodiment of the present invention; fig. 2 shows a schematic diagram of a set of topologically dispersed short paths from node 1 to node 6, which is obtained by calculation according to the calculation method given in the present invention for the network shown in fig. 1, and the paths in the set are represented by dashed lines with arrows, namely path 1 → 2 → 6, path 1 → 3 → 6, and path 1 → 4 → 5 → 6, respectively.

Detailed Description

The invention is further described below with reference to the drawings and an embodiment.

Example (b): referring to fig. 1 and 2, a method for calculating a network topology dispersed short-path set based on a path expansion and elimination mechanism includes the following steps when calculating a topology dispersed short-path set from any node o to another node d in a network:

step 1: an empty path set omega is created, and an empty path set S is created for each node i except the node o in the network_o,iAnd a variable l with a value of positive infinity_o,iWherein l is_o,iFor storing sets S_o,iLength of the shortest path in (1);

step 2: traversing each neighbor node j of the node o, and simultaneously adding the direct path o → j from the node o to the node j into omega and S_o,j；

And step 3: if omega is empty, jumping to step 6;

and 4, step 4: taking out a path P with the shortest length from the omega and removing the path P from the omega; and then traversing each neighbor node t of the node s for the tail node s of the path P, and if the node t does not appear in the path P, executing the operations of the steps 4.1-4.4:

step 4.1: expanding the path P by using the node t to obtain a path P → t;

step 4.2: if the length of the path P → t is less than l_o,t×α, the path P → t is added to S_o,tSimultaneously update l_o,tIs S_o,tLength of the shortest path in (1); then delete S_o,tAll lengths in are greater than l_o,t×α;

step 4.3: if S_o,tComprising β +1 paths, then first for each node k in the network, statistics S_o,tHow many paths pass through the node k is called the topology overlapping cost of the node k; then from S_o,tEliminating another path except the path with the shortest length, wherein the sum of topology overlapping costs of all nodes passing through the path is the largest;

step 4.4: if the path P → t exists in S_o,tIn, the path P → t is added to Ω.

And 5: skipping to the step 3;

step 6: when the operation is finished, return to S_o,dAs a topological dispersed short path set from node o to node d.

In the above step, the length of the path is defined as the number of nodes through which the path passes, α is an adjustable parameter for controlling an upper limit of the length of the path in the topology distributed short-path set, and a value of α is greater than 1.0, and β is an adjustable parameter for controlling an upper limit of the number of paths in the topology distributed short-path set, and a value of β is greater than or equal to 1.

In this example, let α be 1.5 and β be 3, taking as an example a set of topology-distributed short paths for nodes 1 to 6.

Firstly, according to the step 1: an empty path set omega is created, and an empty path set S is created for each node i except the node 1 in the network_1,iAnd a variable l with a value of positive infinity_1,i. The results of the runs are shown in Table 1, line 1.

Then, according to the step 2: traversing each neighbor node j of the node 1, and simultaneously adding the direct path 1 → j from the node 1 to the node j into omega and S_1,jThe run results are shown in Table 1, line 2.

Thereafter, according to step 3, since Ω is not empty, step 4 is performed: taking out the path P with the shortest length from omega as 1 → 2 and removing the path P from omega; and then, for the tail node s of the path P being 2, traversing each neighbor node t of the node s, and if the node t does not appear in the path P, executing the operations of steps 4.1-4.4. Meanwhile, on the basis of the path 1 → 2, the paths 1 → 2 → 5 and 1 → 2 → 6 are extended by the neighbor nodes 5 and 6 of the node 2, respectively, and are added to S_1,5And S_1,6And simultaneously added to omega, the run results are shown in table 1, line 3.

Then, according to step 5, step 3 is executed, and since Ω is not empty, step 4 is executed: taking a path P with the shortest length from omega as 1 → 3, removing the path P from omega, traversing each neighbor node t of the node s for the tail node s of the path P as 3, and executing the operations of steps 4.1-4.4 if the node t does not appear in the path P, wherein the operation result is shown in the 4 th row of the table 1.

And then, repeating the operations of the steps 5, 3 and 4 for multiple times, wherein the operation results are shown in the 5 th to 15 th rows of the table 1. During the period, the paths involved in partial expansion in the operations of the 6 th, 7 th, 9 th, 11 th, 12 th, 13 th, 14 th and 15 th rows are eliminated due to too long length, and the paths involved in the expansion path set in the operations of the 8 th, 9 th, 10 th and 11 th rows are eliminated due to the over-limit number of paths and the maximum sum of topological overlapping costs.

For example, in the operation of line 6, the expanded path 1 → 2 → 5 → 4 is eliminated because it is too long, i.e., its length exceeds the shortest path 1 → 4 by α which is 1.5 times the length, and thus is not addedOmega. In the operation of line 8, since S is after adding the expansion path 1 → 3 → 4 → 5_1,5Contains 4 paths, exceeds the upper limit of β -3, and is counted for S_1,5And the topological overlapping costs of the nodes 1-6 in the network are respectively as follows: 4.2, 1, 2, 4, 1, since the sum of the topological overlapping costs of the respective via nodes of the path 1 → 2 → 6 → 5 and the path 1 → 3 → 4 → 5 is the maximum value 11 at the same time except for the shortest path 1 → 2 → 5 in the set, the path 1 → 3 → 4 → 5 is randomly eliminated in this example, and therefore, the path is not added with Ω.

And finally, because omega is empty, executing the operations of the steps 5, 3 and 6 to finally obtain the topology dispersed short path set S from the node 1 to the node 6_1,6。

TABLE 1 results of the step execution in the examples

The foregoing is illustrative of embodiments of the present invention and is provided for the purpose of clarity. Any modification and equivalent substitution made of the present invention within the spirit of the present invention and the scope of the claims will fall within the scope of the present invention.

Claims (1)

1. A network topology dispersion short path set calculation method based on a path expansion and elimination mechanism is characterized in that: the steps of calculating the topology dispersed short path set from any node o to another node d in the network are as follows:

step 1: an empty path set omega is created, and an empty path set S is created for each node i except the node o in the network_o,iAnd a variable l with a value of positive infinity_o,iWherein l is_o,iFor storing sets S_o,iLength of the shortest path in (1);

step 2: traversing each neighbor node j of the node o, and simultaneously adding the direct path o → j from the node o to the node j into omega and S_o,j；

And step 3: if omega is empty, jumping to step 6;

and 4, step 4: taking out a path P with the shortest length from the omega and removing the path P from the omega; and then traversing each neighbor node t of the node s for the tail node s of the path P, and if the node t does not appear in the path P, executing the operations of the steps 4.1-4.4:

step 4.1: expanding the path P by using the node t to obtain a path P → t;

step 4.2: if the length of the path P → t is less than l_o,t×α, the path P → t is added to S_o,tSimultaneously update l_o,tIs S_o,tLength of the shortest path in (1); then delete S_o,tAll lengths in are greater than l_o,t×α;

step 4.3: if S_o,tComprising β +1 paths, then first for each node k in the network, statistics S_o,tHow many paths pass through the node k is called the topology overlapping cost of the node k; then from S_o,tEliminating another path except the path with the shortest length, wherein the sum of topology overlapping costs of all nodes passing through the path is the largest;

step 4.4: if the path P → t exists in S_o,tIn, add path P → t to Ω;

and 5: skipping to the step 3;

step 6: when the operation is finished, return to S_o,dAs a topological dispersed short path set from node o to node d;

in the above step, the length of the path is defined as the number of nodes through which the path passes, α is an adjustable parameter for controlling an upper limit of the length of the path in the topology distributed short-path set, and a value of α is greater than 1.0, and β is an adjustable parameter for controlling an upper limit of the number of paths in the topology distributed short-path set, and a value of β is greater than or equal to 1.

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