I. Introduction
Multicasting is a transmission method used in packet switched networks mainly for delivering voice and multimedia data from one to many receivers at the same time. This technique requires efficient routing algorithms defining a tree with a minimum cost between the source node and particular nodes representing the users. Such a solution prevents duplication of the same packets in the links of the network. Routing of the sent data occurs only in those nodes of the network that lead directly to destination nodes. The implementation of multicasting requires solutions of many combinatorial problems accompanying the construction of optimal transmission trees. In the optimization process one can distinguish: MST (Minimum Steiner Tree), and the tree with the shortest paths between the source node and each of the destination nodes SPT (Shortest Path Tree). Finding the MST, which is a -complete problem, results in a structure with a minimum total cost [1]. Relevant literature provides a wide range of heuristics solving this problem in polynomial time [2], [3], [4]. From the point of view of the application in data transmission, the most commonly used is the KMB algorithm [2]. Other methods minimize the cost of each of the paths between the sender and each of the members of the multicast group by forming a tree from the paths having the least costs. Doar and Leslie [5] show that the total cost of MST constructed by the KMB heuristic is on average 5% worse as compared to exact the MST algorithm [6].