Contentionless transmission in buffer-less slotted optical packet switched networks

•Propose CLTOPS protocol for buffer-less slotted OPS networks to reduce packet loss rate.•Use traffic smoothing in ingress switches and send long time waited packets as unreserved optical packets.•Use slot reservation to assure no dropping of reserved optical packets using an innovative signaling and reservation method.•Our reservation method relies on natural characteristics of the slotted OPS.•CLTOPS reduces PLR without using any additional hardware while controlling buffering delay.

Contention of optical packets in optical packet switched (OPS) networks is a major problem, and it is even more critical in buffer-less OPS networks. In this paper, an innovative contention avoidance technique is proposed which uses combination of special traffic shaping at ingress switches and special time slot reservation technique through the path of traffic flows in core network. This novel protocol is called contentionless transmission OPS (CLTOPS) suitable for buffer-less slotted OPS networks. Performance evaluations show that the CLTOPS can outperform the original slotted-OPS architecture in terms of packet loss rate (PLR) performance, with or without using wavelength conversion. It is shown that there is a trade-off between the amount of improvement in PLR and additional delay applied to the users’ packets at the ingress switches buffers. However, appropriate parameters can be selected to make the additional delay tolerable for users’ applications.