Debugging Network Reachability with Blocked Paths

Abstract In this industrial case study we describe a new network troubleshooting analysis used by VPC Reachability Analyzer , an SMT-based reachability and debugging tool. Our uses formal model of AWS Virtual Private Cloud (VPC) semantics to identify whether destination is reachable from source in given configuration. the where there no feasible path, our derives blocked path : infeasible but otherwise complete that would be if corresponding set configuration settings were adjusted. differs other academic commercial offerings either rely on packet probing (e.g., tcptrace ) or provide only partial paths terminating at first component rejects packet. By providing (but infeasible) destination, for user all they will need alter admit (instead requiring them repeatedly re-run after making changes). This allows users refine their query so aligned with intended behavior before any changes