In this seminar, we give an introduction to optical burst switching (OBS) and compare it with other existing optical switching paradigms. Basic burst assembly algorithms and their effect on assembled burst traffic characteristics are described first. Then a brief review of the early work on burst transmission is provided followed by the description of a prevailing protocol for OBS networks called Just-Enough-Time (JET). Algorithms used at an OBS core node for burst scheduling as well as contention resolution strategies are presented next. Tradeoffs between their performance and implementation complexities are discussed. Recent work on QoS support, IP/WDM multicast, TCP performance in OBS networks and Labelled OBS is also described, and several open issues are mentioned
In the OBS paradigm, only a few control channels (e.g., one per fiber) go through O/E/O conversion . Given that the data is switched ail-optically at burst level, data transparency and statistical multiplexing can be achieved concurrently. Since OBS takes advantage of both the huge capacity in fibers for switching/transmission and the sophisticated processing capability of electronics, it is able to achieve cost reduction and leverage the technological advances in both optical and electronic worlds, which makes it a viable technology for the next generation optical Internet.
At an OBS node, no synchronization/alignment of bursts is necessary unless the switching fabric operates in a slotted manner. In addition, FDLs and wavelength converters which are optional can help in reducing burst loss. Currently, it is a challenge to implement an OBS switching fabric with hundreds of ports operating at a switching speed which is on the order of nanoseconds. Nevertheless, on-going research work has shown promise
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