Running pf_stat or nf_stat without an interval and count displays the total number of lost frames since the interface was activated. Running pf_stat or nf_stat with an interval and count displays the number of lost frames since the last interrogation. A lost frame is defined as an SMT frame whose reception is aborted by the local station. It does not indicate the location of the cause of the error. A large number of lost frames can indicate a noise problem on the network, either dirt (optical fiber) or electrical interference (UTP).