A device validates reachability of nodes of a communication network of an industrial automation and control system. The device includes a collector module configured to update a data set including discovered dataflow information by detecting direct neighbor nodes having a physical connection to a selected node, and updating the data set by adding the selected node and those direct neighbor nodes which have configured logical network constraints matching logical network constraints of the selected node. The device includes a repeater module configured to repeat the selecting of a direct neighbor node in the data set and directing the collector module to update the data set using the selected direct neighbor node. The device includes a validation module configured to validate reachability of nodes of the network by comparing the data set with a data set including designed dataflow information which defines reachability requirements for nodes of the communication network.