This paper reports a test bed aiming at studying burst contention resolution mechanisms in ldquoLabelledrdquo OBS networks together with a simulation tool that is designed to back up experiments. The test bed is composed of a Labelled OBS core node and a measurement arrangement for burst capture and analysis. Different components of the test bed are presented together with their measured characteristics. The simulation tool is presented with a preliminary simulation that compares the Labelled OBS scheme with the conventional BCP OBS scheme. The results show that the Labelled OBS scheme outperforms the conventional OBS scheme.

This paper describes the work carried out in the RACE Project R2039 ATMOS (asynchronous transfer mode optical switching). The project is briefly illustrated, together with its main goal: to develop and assess concepts and technology suitable for optical fast packet switching. The project's technical approach consisted in the exploitation of the space and wavelength domains for fast routing and buffering: The major achievements are then reported. Four different switch architecture concepts have been proposed, investigated and developed, all based on a high speed optical routing matrix electrically controlled at lower speed. The basic optical key components and subsystems (wavelength converters, space switches and optical buffers) are described in detail, with the outstanding results obtained and the corresponding projected performance. In particular, system demonstration of wavelength conversion at 10 and 20 Gb/s has been realized, to show the usefulness of the ATMOS technology both to implement optimized high performance optical packet-switching fabrics as well as transparent optical circuit-routing nodes. Four rack-mounted, reduced size demonstrators of basic switching matrices have been designed and implemented scalable to real system sizes. The obtained good results in terms of bit error rate and hardware integration are reported, showing that ATM switches are feasible with state of-the-art optical technology.

An optical buffer shift register based on a set of fiber delay lines is presented, with the goal of providing cell storage and queuing in asynchronous transfer mode (ATM) photonic switches. The concept of multiwavelength cell buffering is adopted, to realize a shared buffer with a storage capacity equivalent to a set of shift registers. Since only one wavelength-encoded cell must enter one delay line at each time slot, contention resolution is necessary to determine the queuing order between the incoming cells. The use of optical fibers as delay lines and semiconductor optical amplifiers as gates associated with passive splitters to realize buffering and time-switching has been demonstrated. An experimental setup has been implemented at 600 Mb/s and operates without guard bands between packets. The low penalty observed shows that system synchronization and reliability are good.>