A novel and simple beforehand bandwidth reservation (BBR) MAC protocol for OBS metro ring networks

This paper proposes a novel and simple MAC protocol called beforehand bandwidth reservation (BBR) to reserve the empty slots in the next big-slot cycle for OBS ring networks by control channel. The node architecture uses one tunable transmitter and one fixed receiver to add or drop data channels and a fixed transmitter/receiver pair to transmit and receive on the control channel. Each node possesses a dedicated channel to receive data, so it inherently occupies a priority position. Fortunately, a well-known packet scheduling approach, time-division multiplexing (TDM), can overcome this problem. In addition, the length of the big-slot cycle is studied with a view to investigating performance divergence. Finally, a multi-token protocol using the (FTW–FRW) node architecture is compared with the BBR protocol. According to simulation results, the BBR scheme using the TDM approach achieves the best bandwidth utilization (more than 95%), while the multi-token protocol achieves the worst performance based on packet distribution in the MCI backbone.