Efficiency of OBS networks

In this paper, we evaluate, for certain scenarios, the achievable level of utilization of OBS networks while maintaining acceptable blocking probability. We consider bufferless optical burst switching (OBS) networks with deflection routing, in which channel reservation is used to avoid instability, and with realistically high number of channels per trunk. The blocking probability is evaluated based on the Erlang fixed-point approximation and the overflow priority classification approximation. We demonstrate that a fully meshed OBS network can achieve close to 90% utilization meeting 10 ⁶ blocking probability and for a topology such as NSFNET, for an arbitrary set of source-destination pair, key bottleneck links can also achieve high utilization, while some unutilized links may lead to lower overall utilization. However, there is no evidence that the efficiency of OBS in case of large number of links per trunk is significantly lower than that of circuit switching equivalent alternatives, if the target blocking probability is low. We also demonstrate that for high number of links per trunk, with low target of blocking probability, deflection will not significantly improve efficiency.