This read-only counter tracks the number of CLNP PDUs that had to be discarded because they needed to be fragmented at this entity but the fragmentation could not be performed. An admin seeing this counter increase would suspect a PDU exceeding some hard limit that even segmentation cannot work around, or a resource shortfall preventing the segmentation process itself. For example, a persistent nonzero value here alongside successful segmentation of other PDUs might point the admin toward one specific oversized or malformed PDU type that the segmentation logic cannot handle.