Traffic characterization of transport level reliable multicasting: Comparison of epidemic and feedback

Ozkasap O., Caglar M.

Transport level multicast protocols providing reliability and scalability properties are certainly essential building blocks for several distributed group applications. We consider the effect of reliable multicast transport mechanisms on traffic characteristics and hence network performance. Although self-similarity property of unicast traffic, in particular TCP, has been analyzed extensively, multicast traffic has not been incorporated from this perspective. In this study. we focus on traffic characterization of transport level reliable multicasting. In particular, we concentrate on two scalable and reliable multicast protocols as case studies, namely Bimodal Multicast and Scalable Reliable Multicast (SRM), and analyze the traffic generated by them. Our study consists of a complete simulation analysis supported by theoretical work, which shows that self-similarity is protocol dependent. We demonstrate that the Markovian character of Bimodal Multicast^ epidemic loss recovery distinguishes an inherently superior protocol. It discretely feeds well-behaved traffic and copes with the existing self-similarity. On the other hand, the feedback controlled loss recovery mechanism of SRM triggers self-similarity. Drawing upon both theoretical and simulation analysis, our results substantiate that transport level can induce long-range dependence even in the absence of application/user level causes.