In spite of its long term promise, all-optical switching is still plagued by high cost, low efficiency when handling bursty data traffic, immature management and protection and poor output port contention resolution leading to heavy loss. Given the current situation, hybrid approaches that keep the best features of optics, reverting to the electrical plane when expedient, constitute sensible interim steps that can offer cost-effective solutions along the road to an eventual all-optical core. Two such approaches developed in the framework of the European IP project NOBEL are presented in this work. The first is a quite mature solution that extends present day concepts to achieve multiplexing gain while keeping all the management and restoration benefits of SDH. The other mimics early LANs in executing a distributed switching via its electrical control plane using two-way reservations, thus restricting its applicability to smaller domains. Combining the two leads to a system fulfilling most of today's requirements for Tb/s core networks.
To meet the demand for higher performance, flexibility, and economy in today's state-of-the-art networks, great emphasis is placed on unconventional hardware architectures of network processors. This paper analyzes the problem of processor internal resource and traffic management and proposes a programmable scheduler architecture implemented in a novel protocol processor that deals with the above problems in an integrated way. We briefly outline the architecture of the protocol processor and we support that the innovative scheduling scheme integrated in PRO3 is, in general, crucial for network Systems-on-Chip since it makes it feasible to use scheduler's architecture are discussed that lead to efficient integration of the component to different network processor architectures at a similar cost. Its beneficial features are easy hardware implementation, low memory bandwidth requirements and high flexibility so as to support multiple service disciplines in a programmable way, thousands of flows and even perform different scheduling tasks.