Abstract: Before packets enter a router, a packing limiting unit abandons out-of-order packets, decreases a window size, and stores temperately part of said out-of-order packets for having packets pass the packet limiting unit with a better efficiency and a precise order. After packets enter said router, a packet retransmission processing unit acquires a characteristic values and messages calculated from each characteristic value of a packet for obtaining the order, size, header, and check bits for assisting in identifying packets, and stores the characteristic values with a link list for saving memory utility. With both the abovementioned methods, problems of out-or-order and retransmission during packets are transmitted, and of an over-used amount of memory, are solved.