This counts SLM test frames this device dropped specifically because it ran out of local resources needed to process them as a responder, for instance too many concurrent synthetic-loss sessions already being serviced, or an internal table of active test contexts being full. This is a capacity-limit signal distinct from the frame-integrity counters elsewhere in this table: it says the frames were fine, this device simply could not keep up. An admin seeing this counter increment while running several simultaneous SLM test sessions against this device would know to reduce concurrent test load rather than suspect a network problem.