The size, in octets, of the largest IP datagram this device can reassemble from fragments arriving on this specific interface. This caps how large a fragmented datagram can legitimately complete on that interface; traffic engineered with a reassembled size beyond this limit will always fail reassembly here regardless of ipReasmTimeout, a useful distinction when diagnosing why some large fragmented flows never complete on one interface but do on another. Example: ipAdEntReasmMaxSize reading a lower vendor-imposed limit on one interface than another explains why an unusually large fragmented UDP datagram reassembles fine on one link but consistently fails on the other.