This Counter64 reports the total elapsed time, in seconds, spanned by this path-layer measurement bin. Because this is the cumulative TdmPwTotalStatistics counter for the pseudowire, tallied since the bin's own start time rather than being reset every short collection interval, Ttp is essentially the denominator for every seconds-based path counter in this row (Asp, Esp, Sesp, Uasp) — without it those counts can't be turned into percentages. For example, a Ttp of 900 confirms this row genuinely covers a 15-minute bin, so an Uasp of 10 seconds in the same row means 10 out of those 900 seconds were unavailable.