Abstract: A SDN controller is configured to generate and install a tracing table with tracing rules into switches of a SDN based on a switch level in a network topology of the SDN; identify a source switch and a destination switch for tracing a trajectory path of a transit packet; generate a probe packet; set all bytes in a source address to zero and initialize a DSCP field to 16; inject the probe packet into the source switch; encode selective ingress ports of intermediate switches within the trajectory path into the source address of the probe packet; receive the probe packet when the probe packet reaches the destination switch; and reconstruct the trajectory path of the transit packet, via encoded information in the source address of the probe packet, wherein the reconstructed trajectory path is constructed via the encoded selective ingress ports of the one or more intermediate switches.