Flow engineering method applicable to software defining network

The invention discloses a flow engineering method applicable to a software defining network, comprising steps of obtaining network topology, link capacity, business flow collection and approximation parameters, initializing a link length, a first flow variable and a second flow variable, classifying the business flows having identical source nodes into one class, successively performing bandwidth distribution on the business flow of each kind and outputting the final bandwidth distribution scheme. Although the invention is based on the approximation algorithm, the obtained approximate solution is very close to the optimal solution which is obtained through the linear programming. In the meantime, the approximation algorithm brought forward by the invention is not sensitive to the approximation rate parameters. Compared with the approximation algorithm, the target function value obtained through adopting a relatively big approximation parameter is very close to the target function value which is obtained through adopting the relatively small approximation parameter. Because the approximation algorithm brought forward by the invention is identical to the approximation algorithm in the calculation complexity, the calculation efficiency can be dramatically improved by choosing a relatively big approximation parameter, which is very meaningful to the flow engineering of the big scale network.