A wavelength assignment and traffic control scheme in reservation slotted OBS rings

In this paper, we design a slotted OBS ring with a proposed reservation signaling protocol. Also, the slotted OBS ring is designed with a wavelength assignment and traffic control (WATOR) scheme to achieve high bandwidth utilization, fairness, and stability. The WATOR scheme adopts a reservation mechanism to avoid burst collisions in the slotted OBS ring system which employs no transit buffers in each node for the reason of bypassing the traffic directly. It is sophisticatedly composed of a wavelength assigner to effectively allocate the ingress data bursts (DBs) with a wavelength and a traffic controller to determine a proper advertised fair rate. The TC further contains a local fair rate generator (LFRG) and an advertised fair rate generator (AFRG). The former generates a local fair rate not only to satisfy the ring ingress aggregated with spatial reuse (RIAS) fairness but also to diminish the effect of the propagation delay; and the latter decides the advertised fair rate referring to the local fair rate generated by the former. Simulation results show that the WA achieves system utilization higher than a group scheduling (GS) scheme [11] by about 5%, and the TC can stabilize all flows much better than but DBA [12].