Hopcount in Application Layer Multicast Schemes

Application Layer (AL) multicast protocols emerged, and in large number, as a response to the slow deployment of IP multicast. However, the gain of different AL multicast mechanisms,,in terms of resources consumption over unicast, is questionable. In this paper, we investigate the efficiency of AL multicast protocol NICE, in terms of the number of hops a packet traverses on its path toward the destinations. We propose four alternative algorithms for the creation of NICE overlay and compare their efficiency to the efficiency of unicast, IP multicast, and another two previously evaluated AL multicast protocols (MCAN and Scribe). Further, we investigate the influence of the underlying topology awareness on the efficiency. Our analysis has been performed via simulations, as well as via measurements on the PlanetLab network. We show that the NICE structure achieves better results than MCAN and Scribe.