An Enhanced Train Assembly Policy for Lossless OBS with CAROBS

The traffic evolution is notoriously marked by an increasing dynamism that promotes the design of a dynamic optical layer. Despite the contention issue, Optical Burst Switchingis planned to be deployed in the near future because it offers the required reactivity.Recourse to electrical processing to solve burst contentions has been disregarded because it can dramatically impact the end-to-end delay and the electrical memory requirements. Recently, the CAROBS transmission scheme has been proposed as an adapted response to the drawbacks of translucent architectures: By exploiting both edge and core traffic grooming, CAROBS significantly reduces the contention rate and the duration of the aggregation process. With the additional use of wavelength conversion, loss-less transfer is achieved with similar end-to-end delay and memory requirements as in all-optical OBS networks.The objective in this paper is to attain similar delay and memory performances for loss-less transfers without the support of wavelength converters. We propose a new train assembly process, called CTA, which reduces the time spent in electrical buffers by decreasing the offset times of the trains. The resulting reduction of the buffer occupancy allows the achievement of similar performances as with wavelength conversion, even in congested states, without investing in any specific equipment.