An approach to improve TCP throughput of long-hop connections in bufferless OPS networks

Optical Packet Switching (OPS) can provide the ever-increasing bandwidth required for Internet traffic and new applications in future networks. However, optical packet loss is the major problem for an OPS network. In addition, by increasing the number of hops between a pair of ingress-egress switches in an OPS network, optical packet loss rate between this pair is increased. Due to a higher loss rate for longer-hop TCP connections, the throughput of these connections may be much lower than the shorter-hop TCP connections. To overcome this problem, it is proposed in this paper to use the retransmission idea in the optical domain. This scheme not only increases TCP throughput but also improves the throughput of multi-hop TCP connections. Note that TCP layer has its own retransmission at packet level as well. In this paper, TCP throughput is studied in a bufferless slotted OPS network and the effectiveness of the proposed mechanism is evaluated.