1. A method performed by a data processing system for network fault isolation, the method comprising steps performed by the data processing system of: responsive to receiving a request for the network fault isolation between a sender and a receiver, performing a plurality of real-time path tracing between the sender and the receiver to form a plurality of trace paths; determining whether an asymmetry is present between the sender and the receiver from the plurality of trace paths; identifying a set of routers included in each trace path in the plurality of trace paths to form a plurality of identified routers; and identifying each event stored for the plurality of identified routers to form a set of identified events, wherein the each event is collected from the plurality of identified routers and stored in an event store maintained by the data processing system.