Prioritized Buffer Management in Photonic Packet Switches for DiffServ Assured Forwarding

We study photonic packet switching architecture that enables a high node through-put and provides priority services in DiffServ (Differentiated Services). As we will show in this paper, a photonic packet switch can be equipped with an ultra-high-speed address-lookup capability in the optical domain. However, the optical buffer must be managed in the electrical domain. In this paper, we investigate buffer management schemes with less complexity, such that the capability of the ultra-high-speed packet forwarding can be sustained in the photonic switch. We propose an implementation method for PBS (Partial Buffer Sharing) that provides DiffServ AF (Assured Forwarding). We show that PBS is applicable to single-stage optical buffer. Also, we propose a new buffer management method, called PBSO (PBS with Overwriting), which is applicable to broadcast-and-select-based single-stage optical buffer. PBSO is also applicable to the current space-switch-based single-stage optical buffer with an addition of a few optical components. The PBS and PBSO methods are based on a single queue and their complexities are ¥ is the number of levels of drop precedence. Through simulation study, we show that both methods provide different levels of drop precedence for DiffServ AF, and that PBSO improves buffer utilization and the packet loss probability of both drop-level packets.