This field reports the number of defer packets transmitted on the port, exposed here as cienaCesPmExtendedTxRxTotalStatsBinTxDeferPkts. On this Ciena CES port's PM data, this counts frames the MAC had to delay transmitting because CSMA/CD sensed the medium was already busy, which is only a meaningful signal if this port is actually running half-duplex or sitting on a shared/hub segment — a modern full-duplex link should hold this at zero; and this is the running grand-total counter for the extended Tx/Rx PM group, tallied since the bin's own StartTime (in practice since the PM instance was created or last reset), so treat it as a lifetime tally rather than a per-interval number. For example, a link under light load might show a low but steady 40 deferred frames for this bin; it's the rate of growth, not the presence of a nonzero number, that would flag a real problem.