A core-based forwarding multicast protocol uses a core router as a traffic transit center : all multicast packets are first sent to the core, then distributed to destinations on a multicast tree rooted at the core. The purpose of this paper is to evaluate, via simulation, the effect of various core selection methods on multicast performances. Performances metrics of interest include network ressource usage, packet delay, the join time of multicast participants and link congestion. In addition we assess the feasability of these heuristics in real-world environments.