This counter reports the cumulative time, in TimeTicks, that this T1/E1 interface has spent with its transmit clock lost since the system last started up. A nonzero and growing value signals a clocking problem on the line, often caused by a faulty cable, card, or upstream timing source, that an admin should investigate before it leads to bit errors. If dsx1ExtCfgLossTxClock reads 0, the port has never lost its transmit clock since boot; a value of 12000 (2 minutes) indicates a brief clock outage occurred.