This is a cumulative count of packets transmitted out this port since the last reset, the outbound counterpart to cdx6500allportsPktInTot. An admin uses this alongside the inbound count to establish a baseline packet rate for a given port, which becomes the reference point for later recognizing an abnormal drop or spike in that port's packet activity. For example, a port whose PktOutTot suddenly stops incrementing while PktInTot keeps climbing would indicate the port can receive but has stopped transmitting, pointing at a transmit-side fault.