Showing papers by "Helen C. Leligou published in 2007"

An Optical Network Architecture With Distributed Switching Inside Node Clusters Features Improved Loss, Efficiency, and Cost

Abstract: The novel core network architecture presented in this paper realizes distributed all-optical switching of payload by partitioning the network into a number of geographically limited domains, where two-way reservations are effective. Thus, inside each domain, loss is eliminated, while traffic from many nodes can be aggregated into single bursts, improving efficiency. Clustered nodes contribute contiguous optical slots, which are marshaled into composite optical frames destined for other clusters, under the guidance of a reservation-based control protocol. The lossless aggregation of traffic from several core nodes allows the use of cost-effective bufferless all-optical transport among the domains with electrical buffers employed at the periphery of the system. The end result is a triple improvement in loss probabilities, efficiency, and cost. This is achieved by exploiting three features of the architecture: the distributed switching functionality (as in early LANs when centralized switching was expensive), localized reservations (avoiding the intolerable delays of end-to-end reservations), and a reduced number of source-destination pairs (by means of node clustering into reservation domains)

Efficient resource allocation with service guarantees in passive optical networks

Abstract: Feature Issue on Passive Optical Network Architectures and TechnologiesWe propose and evaluate a resource allocation scheme for time-division multiplexing passive optical networks (PONs), which supports multiple service classes; dynamic bandwidth allocation for services with varying (in time) capacity demand; and bounded quality of service parameters for services with real-time requirements. Although several algorithms have been proposed in the literature considering several of the above objectives in isolation, our work focuses on the fundamental problem of trading-off between PON upstream channel utilization and strict delay and jitter bounds when supporting a dynamically changing mix of services with different requirements.

Analytical Evaluation and Implementation of a Novel Slotted Optical Switching Scheme with Two Way Reservations

Abstract: Optical Burst Switching achieves multiplexing gain in the optical domain but cannot reach reasonable utilization before burst losses become unacceptable. In this paper, we analytically evaluate a novel method to avoid these losses by first sending over the control channel a short scout packet that simulates the events that the actual packet will experience. Once the scout message detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeated. The penalty is the delay for the implicit reservations and the occasional process repetition, limiting the applicability of this approach to a periphery of no more than just few thousand kilometers. A slotted approach is adopted to facilitate accounting of data and allow for pipelined operation which improves performance. We also evaluate the implementation complexity of the proposed scheme to prove its feasibility and the avoidance of congestion on the control channel.