Hardware aided time stamping of Ethernet frames is used to implement a two way time transfer. The method is capable to either operate actively by initiating or relaying frames, or passively by utilization the traffic on, preferably, optical links. Time stability of unfiltered measurements taken on local links is about 3.5 ns @ 1s TDEV, reaching below 1 ns for time intervals of about 100s. The presented method is specific to a family of commercial traffic analyzers, but can be generalized for any similar capable hardware.