A model for replica placement in content distribution networks for multimedia applications

The distribution of multimedia files brings new challenges to the problem of replica placement in content distribution networks (CDN) and invalidates several assumptions underlying the existing solutions. In this paper we formulate a new model for the problem of replica placement to accommodate these new characteristics. We perform a theoretical analysis of the cost of distributing multimedia files over CDNs and find out that, contrary to the intuition, deploying as many replicas as possible is not always a good strategy. We then propose several replica placement algorithms that can determine the optimal number of replicas we should select from a given set of potential sites. By simulation we demonstrate that the performance of clients may degrade if we choose too many sites for replica placement.