Recent mechanisms for multicast involve selection of a \textsl{core} router through which all communications of a multicast group are routed. The purpose of this paper is to evaluate the performance impact of certain choices in the core selection. We proposed and compare the simulated performances of simple heuristics to efficiently support dynamic multicast group, and more generally, multicast core management by allowing the core to migrate. Performance metrics include network resource usage, end-to-end delay and join time. Our aim is to provide simple heuristics that make use of the informations and facilities provided by the underlying routing protocol, \textsl{i.e.}, \textsl{link-state routing}. The results of a simulation study reveal that the proposed heuristic based on the topological center of a multicast tree obtains very good performance and uses network resources efficiently.