The application of Steiner trees to delay constrained multicast routing: a tabu search approach

With today´s development of information technology comes the increased development of numerous real-time multimedia network applications. Some examples include video and teleconferencing, telemedicine, video-on-demand, distance education, applications in finance, etc. Several of these applications require multicasting with a certain quality of service (QoS). One of the most important QoS parameters is the maximum end-to-end delay from the source to any destination in a multicast session. This paper deals with the problem of delay-constrained multicast routing (DCMR). The DCMR problem can be reduced to the constrained minimum Steiner tree problem in graphs (CMStTG). Since the minimum Steiner tree problem in graphs (MStTG) has been proven to be NP-complete, several heuristics have been developed for solving MStTG and CMStTG. In this paper, we suggest a tabu search heuristic for the DCMR problem. This heuristic was developed on the basis of a tabu search heuristic designed for solving unconstrained minimum Steiner tree problems. Preliminary testing on data from a publicly available library, SteinLib, has shown that this heuristic gives near optimal solutions in moderate time and a moderate number of iterations for medium sized problems (50-100 nodes). Comparing with a well known algorithm for solving the CMStTG problem, tests have shown that our tabu search heuristic is superior in quality for medium sized problems.