This field reports the total number of packets received that were less than 64 octets long (excluding framing bits, but including FCS octets) and were otherwise well formed, exposed here as cienaCesPmExtendedTxRxTotalStatsBinUndersizePkts. On this Ciena CES port's PM data, these are frames shorter than the 64-octet Ethernet minimum that were nonetheless well-formed (good FCS, no alignment error), so a nonzero count points at an attached device intentionally or accidentally generating non-standard short frames rather than at wiring damage; 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 healthy port would sit at 0 for undersized-but-valid frames in this bin; even 28 is enough to warrant a look, since this class of counter isn't supposed to move under normal operation.