Traffic Behavior of Scalable Multicast: Self-similarity and Protocol Dependence

The development of high-speed networks and the expansion of the Internet have increased both geographical extent and participant population of applications such as videoconferencing, multimedia dissemination, electronic stock exchange, and distributed cooperative work. The key property of this type of applications is the need to distribute data among multiple participants together with application specific quality of service needs which fact makes multicast protocols an essential underlying communication structure. In this paper, we analyze traffic characteristics of two scalable multicast protocols, namely Bimodal Multicast (Pbcast) and Scalable Reliable Multicast (SRM), each having different approaches for loss recovery and providing reliability. Particularly, our simulation studies demonstrate that epidemic approach of Bimodal Multicast generates a more desirable traffic than SRM with lower overhead traffic and transport delays. SRM delays show long-range dependence and self-similarity whereas Bimodal Multicast delays are shortrange dependent. Self-similarity and long-range dependence are ubiquitous in wide area networks, which lead to adverse consequences in network performance. We elaborate on the protocol mechanisms as the underlying factor in our empirical results. The intrinsic relation of these mechanisms to traffic characteristics is explored.