NetNORAD: Troubleshooting networks via end-to-end probing

Introduced NetNORAD, an end-to-end probing system for network troubleshooting that treats the network as a black box, independent of device polling. It measures packet loss ratio and latency by having servers ping each other using UDP probes. The system categorizes network issues by proximity (DC, Region, Global) and uses time-series analysis for alarm generation. It incorporates outlier detection for fault isolation and complements fbtracert for hop-by-hop analysis. Key components (UDP pinger/responder and fbtracert) were open-sourced.