or extra power is required uses redundancy and non linear filtering to reduce the likelihood of erroneous results and does not require far end silence or special termination device an auto negotiation method is disclosed which captures the time domain reflection of auto negotiation an pulses by using an internal buffer it then identifies the near and far end echoes and uses the distance between the signal echoes to estimate the cable length it also uses the amplitudes of the far end echoes to determine whether the cable is terminated to a far end phy or if it has an open or shorted wire the presence of actual an pulses from a far end device can cause incorrect measurements due to the resemblance between these pulses and the reflected pulses from the device conducting the test in order to avoid this each measurement is repeated multiple times and the results are calculated and saved for one or more or all iterations using all of the stored measurements the cable length may be chosen by median filter to avoid spurious results an improper termination is determined by whether a majority of the results were flagged for that type of cable fault in one embodiment the method disclosed herein calculates the length of the cable under test for good cables which are terminated by another phy for faulty cables with an open wire or.