A virtual router network (VRN) for performing real-time flow measurements (RTFM) is provided. The VRN effectively reduces the number of traffic metering points required thereby simplifying the aggregation and exportation of flow records to a collector. The collector may be service manager in a network management system. The metering points, in a preferred embodiment, are at virtual interfaces (VI) which are edge nodes in VRN. One of the virtual interfaces is selected as a master virtual interface and act as a collector and distributor of flow related information. In one aspect of the invention the VRN is used to provide, non-invasively, per-flow delay monitoring in a communication system.