Optical Burst Switching Paradigm Research Articles

On the Myths of Optical Burst Switching

This paper discusses merits and drawbacks of the Optical Burst Switching (OBS) paradigm, which received so much attention by the academic research community. Since the topic is hot, and given the several flavors of OBS available in the literature, we first define what we mean by OBS. Then, we carefully design a reference scenario and a set of evaluation experiments that can be used to obtain quantitative answers to interesting questions in a repeatable way. Within this framework, we motivate our skepticism towards two frequent assertions about the OBS paradigm: its ability to (i) exploit the network bandwidth more efficiently than Optical Circuit Switching (OCS) alternatives, and (ii) to efficiently solve contentions without optical buffers.

High-Priority First Transmission to Efficiently Support Service Differentiation in Just-in-Time OBS Networks

The provision of service differentiation is an important aspect that has to be considered for the definition of next-generation networks due to the high heterogeneity of the traffic that will dominate networks in the near future. This is particularly important in the context of optical burst switching, which is emerging as one of the strong candidate technologies for the next-generation optical Internet. Preemptive contention resolution schemes are very effective solutions for providing service differentiation in such networks; however, they cannot be applied together with the just-in-time signaling protocol because of the great loss in efficiency in terms of wavelength utilization and maximum achieved throughput that results when the number of preemptions becomes too large. This paper presents a preemption-based service differentiation solution that is suitable for the just-in-time optical burst switching paradigm because it keeps the preemption probability (i.e., the probability of observing a preemption when a contention occurs) low. Within the proposed technique, bursts are created at their ingress node and combined into chains, arranging them in order of decreasing priority. Then, a conventional preemption scheme is adopted at core nodes to handle contentions. An analytical study is presented and some traffic scenarios are analyzed by simulation to evaluate the performance of the proposed method.

Delay-on-Demand: A Signaling Protocol to Reduce Blocking Probability in Optical Burst-Switching Networks

Optical burst switching (OBS) is emerging as one promising switching paradigm for the next generation optical networks. To support multiple services in burst-switching networks, the OBS paradigm should support some quality-of-service (QoS) provisioning. A major design issue in such networks is to reduce the blocking probability of the bursts arising due to resource contention at the intermediate core router. In this paper, we propose a signaling protocol which we call ‘Delay-on-Demand’ (OBS-DoD), to reduce blocking probability and support QoS in optical burst-switching networks. The proposed scheme guarantees that at least one of the bursts succeeds depending on its priority, propagation delay from the ingress router, and the burst-size when contention occurs at the core router. For this, we use a control packet to delay, in case of a contention, the transmission of bursts at the ingress router. We compare the performance of our proposal, by simulation, with an earlier proposed scheme, and show that the proposed OBS-DoD outperforms the earlier scheme in reducing the blocking probability. For simulation, we generated bursty traffic using an M/Pareto distribution.