Importance of substrate network topology information for achieving effective enhanced resilience in overlay mapping

Abstract

The impact of substrate network topology availability and its accuracy in achieving enhanced resilience in overlay mapping is analysed. Overlay mapping aims to find a mapping solution for a given overlay request whereby substrate network resources are assigned in such a fashion that diversified backup paths can be secured and so provide enhanced resilience whilst meeting a specific quality of service requirement(s). Based on evaluations exploiting a real-network dataset as well as synthetic topologies, the significance of possessing substrate topology information is demonstrated. Moreover, as this information is typically not readily available or is incomplete, mechanisms are compared that can obtain more accurate inferred substrate information in order to improve further the performance of overlay mapping solutions in providing effective resilience.Introduction: For applications associated with a two-layer network, such as overlay topology construction [1] and overlay mapping for achieving enhanced resilience and QoS [2], topology information of the lower layer is essential to secure better performance. These applications typically assume such topology information is available to their algorithms and little state-of-the-art research considers the impact of the substrate topology availability and its accuracy on their resultant performance. Although such topological information may be accessible in the case of single-domain or private networks, it is typically difficult to obtain for applications that span multiple domains (i.e. Autonomous Systems) across the Internet. Hence, active probing based topology inference, as summarised in [3], is often employed.We take the initiative in verifying the robustness of substrate-topology-aware algorithms without assuming substrate topology information is given since it does not generally hold true, especially in the multidomain Internet. To be more specific, we verify the significance of inferred substrate topology information in helping maintain the performance of our previously proposed overlay mapping heuristic [2] in providing resilience. Raw substrate topology information is obtained using the popular topology discovery tool, traceroute [3]. We first briefly present the issues associated with this tool and the problems we address in this Letter. Then, we discuss the impact of the substrate topology information availability and its accuracy by considering realnetwork data as well as synthetic topologies.