Futuristic Department of Energy (DoE) networks for scientific collaboration and science mission will be large, complex "system of systems." They will consist of heterogeneous groups and domains operating at different networking paradigms using various protocols and technologies. Effectively analyzing network status and performance, and identifying existing and potential faults will help automatic network management and ensure services are provided effectively. IAI has been awarded a contract entitled “Scalable Fault Detection and Localization of Network Issues." IAI proposes to develop NetFaultSONAR, a tool to analyze the monitored network as a whole, and assist users like network operators in maintaining, optimizing, and troubleshooting the network. It will take advantage of the existing perfSONAR framework, by taking collected data for existing tools and services as the input for fault detection and localization components. This tool will monitor important network performance in real-time or near real-time. It will automatically collect and retrieve the network data, status and configuration. It will perform cross-layer multi-domain fault detection and analysis to pinpoint the root cause, and assist the user to determine the most efficient action to fix the issues accordingly. Based on the collected information from the monitored network, NetFaultSONAR will detect various types of events online or predict them offline, and provide online fault diagnosis. IAI will also investigate the feasibility of NetFaultSONAR interacting with Software Defined Networking (SDN) devices and controllers to monitor local networks and reconfigure switches to resolve network faults. NetFaultSONAR will lead to an autonomous software tool that significantly improves reliable access to DoE networks, and reduces the cost and risks for network management.