QRPp1-3: Measurement of Path Redundancy for Protection in Enterprise Networks

Application-layer solutions to improve the reliability of realtime applications such as IP telephony exploit the inherent redundancy in networks. Earlier work has shown that the ISP networks provide sufficient redundancy that can be used by such overlay solutions. Enterprise networks, on the other hand, are designed differently from ISP networks, and implementing an overlay on enterprise networks introduces additional constraints. In this paper, we explore the level of redundancy in enterprise networks that would justify an application-layer reliability solution, while taking into account the unique characteristics of enterprise deployments. We report the findings of an empirical study we conducted on nine real enterprise networks of varying sizes. Specifically, we quantify the amount of redundancy in enterprise networks and the protection level that can be achieved by single-hop versus multi-hop overlays. Our results indicate that, among the networks we considered, on average 30% and up to 86% of the nodes on end-to-end paths can be protected. Furthermore, in these networks going from a single-hop overlay to a multiple-hop overlay provided only marginal benefits.