A low-latency and bandwidth-efficient distributed optical burst switching architecture for metro ring

Optical burst switching (OBS) provides statistical multiplexing capabilities at the optical layer with relaxed hardware requirements when compared to optical packet switching. One of the open challenges of OBS is to assemble as many packets as possible in the same burst, while at the same time ensuring low latency of the transmitted packets. The authors propose the use of OBS to realize a geographically distributed packet switch for metro rings. High efficiency of the ring bandwidth and low packet latency are obtained at the ring node by combining a multi-token based protocol for contention less and loss-free transmission of bursts, known as the lightring protocol, with the creation of bursts that contain packets belonging to multiple traffic flows (classified by priority and destination). As illustrated in the paper, the proposed solution yields throughput that is significantly higher than that one offered by a centralized packet switch connected to the ring nodes via dedicated optical circuits. Latency of real time packets is kept at few dozens of milliseconds under a variety of network scenarios. The solution scales well geographically for metro applications.