A computer implemented method, apparatus, and computer usable program code for network fault isolation. A plurality of real-time path traces is performed between the sender and the receiver to form a plurality of trace paths in response to receiving a request for the network fault isolation between a sender and a receiver. A determination is made as to whether an asymmetry is present between the sender and the receiver from the plurality of trace paths. A set of routers is identified with each trace path in the plurality of trace paths to form a plurality of identified routers. Each event stored is identified for the plurality of identified routers to form a set of identified events.