This paper experimentally confirms the throughput characteristics of TCP and Network Direct Memory Access (Network DMA), our proposed data transfer protocol, over a large delay-band-width link. The experiments clarify that the various problems of TCP over large delay-bandwidth links include limited window size, data retransmission mechanism, and protocol processing overhead. The test results suggest that we must improve not only protocol itself but also the protocol processing architecture to realize Gbit/s class throughput over such links. To avoid these problems, Network DMA realizes high speed memory copy across a network by labeling each packet with its memory address without host CPU intervention; protocol processing is done by firmware on the network interface card. Moreover, it realizes selective retransmission by using the memory addresses. Test results show that Network DMA achieves the sustained throughput of 535Mbit/s over a 10,000km 622Mbit/s ATM link and over 400Mbit/s effective throughput even when the cell loss ratio is 10-4.