Service category-to-wavelength selection technique for QoS support in connection-oriented optical packet switching

This paper considers an optical packet-switched node subject to asynchronous, variable-length packets and connection-oriented operation. We firstly address the problem of setting up the optical virtual connections and properly configuring the forwarding table at the node. We do not deal with routing aspects, but with the efficient mapping of the virtual connections to the wavelengths of the output ports. In this context, we suggest a wavelength assignment procedure that improves the node performance in comparison with simple random or balanced schemes. We then address the QoS provisioning problem. While existing solutions focus on applying some forms of resource reservation on top of the contention resolution algorithm, here we propose a method based on the well-known ATM scheme of defining different service categories. In particular, we define a case study with three OPS service categories, and for each category a specific contention resolution algorithm is applied. With such a strategy the algorithms present the problem of a different performance alignment; we solve it by designing an ad hoc optical buffer architecture based on non-degenerate delays. The performance of the final node architecture is evaluated by simulation. The results obtained indicate the merits of this method, which opens up interesting future developments for a whole optical network scenario.