Designing Infrastructure-Based Overlay Networks for Delay-Sensitive Group Communications

Infrastructure-based overlay networks have been proposed to support the quality of service requirements of a wide range of applications. In this paper, we study using infrastructure-based overlay for delay-sensitive low-bandwidth group communications, such as teleconferencing and chat room. In particular, we study where to place overlay nodes (called proxies) to minimize end-to-end delays. We formulate the problem of optimal proxy placement using integer-linear programming and quantify the benefits from using proxies in six real-world networks. We And that, perhaps surprisingly, only two out of the six networks benefit from using proxies. We furthermore use network characteristics to explain these benefits or lack of benefits. Last, for the two networks which benefit from using proxies, we find that a small number proxies (2 to 3) are sufficient to realize most of the performance gains.