Exactly as described, this counts 1519-to-2047-byte frames received on this benchmark port -- sizes beyond the standard Ethernet maximum. This is the receive-side proof that jumbo frames configured via GeneratorHFrameSize or the EMIX "h" letter actually arrived intact rather than being truncated or dropped by some intermediate device with a smaller MTU, which the transmit-side counter alone can't demonstrate. For example, a transmitted count of 10,000 jumbo frames in this range but a received count of only 9,200 would indicate an intermediate hop is silently dropping or fragmenting the largest test frames.