Burst loss reduction schemes in optical burst switching networks

Burst loss is the major problem that faces the development of optical burst switching (OBS) networks. The burst loss is caused by the contention which affects badly OBS performance, especially under a high load. In this paper we propose two schemes: anticipated retransmission (called AR) and admission control (called QAC). AR aims at reducing the burst loss. The basic idea behind AR is to anticipate retransmission of dropped bursts by sending systematically two copies (primary and secondary) of each burst over two different paths. The traffic composed of the secondary bursts has lower priority and does not interfere/contend with the primary traffic. QAC aims at reducing the burst loss inside the network, especially in highly loaded network. The basic idea behind QAC is to block bursts before entering the network in a way to bound the burst loss inside the network. Applying AR to bursts not blocked by QAC reduces further the burst loss. The simulation results show that AR reduces considerably the burst loss in moderately loaded networks and QAC (combined with AR) guarantees an upper bound for burst losses inside the network.