This field reports the number of excessive collision packets transmitted on the interface, exposed here as cienaCesPmExtendedTxRxAllTimeBinTxExCollPkts. On this Ciena CES port's PM data, excessive collisions means a frame was dropped outright after 16 consecutive collision/backoff attempts per the 802.3 algorithm, which only happens when the shared or half-duplex segment on this port is thoroughly saturated; and this 'all-time' counter for the extended Tx/Rx PM group has no fixed rollover schedule of its own — it just keeps accumulating from whenever the PM instance was last cleared, so a single reading only tells you the running total, not a rate. For example, a healthy port would sit at 0 for excessive-collision drops in this bin; even 57 is enough to warrant a look, since this class of counter isn't supposed to move under normal operation.