Davide Cuda

Cost, power consumption and performance evaluation of metro networks

We provide models for evaluating the performance, cost and power consumption of different architectures suitable for a metropolitan area network (MAN). We then apply these models to compare todays synchronous optical network/synchronous digital hierarchy metro rings with different alternatives envisaged for next-generation MAN: an Ethernet carrier grade ring, an optical hub-based architecture and an optical time-slotted wavelength division multiplexing (WDM) ring. Our results indicate that the optical architectures are likely to decrease power consumption by up to 75% when compared with present day MANs. Moreover, by allowing the capacity of each wavelength to be dynamically shared among all nodes, a transparent slotted WDM yields throughput performance that is practically equivalent to that of todays electronic architectures, for equal capacity.

Scalability of Optical Interconnects Based on Microring Resonators

This letter investigates the use of optical microring resonators as switching elements (SEs) in large optical interconnection fabrics. We introduce a simple physical-layer model to assess scalability in crossbar- and Benes-based architectures. We also propose a new dilated SE that improves scalability to build fabrics of several terabits per second of aggregate capacity.

Optical Interconnection Networks Based on Microring Resonators

Interconnection networks must transport an always increasing information density and connect a rising number of processing units. Electronic technologies have been able to sustain the traffic growth rate, but are getting close to their physical limits. In this context, optical interconnection networks are becoming progressively more attractive, especially because new photonic devices can be directly integrated in CMOS technology. Indeed, interest in microring resonators as switching components is rising, but their usability in full optical interconnection architectures is still limited by their physical characteristics. Indeed, differently from classical devices used for switching, switching elements based on microring resonators exhibit asymmetric power losses depending on the output ports input signals are directed to. In this paper, we study classical interconnection architectures such as crossbar, Benes and Clos networks exploiting microring resonators as building blocks. Since classical interconnection networks lack either scalability or complexity, we propose two new architectures to improve performance of microring based interconnection networks while keeping a reasonable complexity.

Optical interconnection networks based on microring resonators

Optical microring resonators can be integrated on a chip to perform switching operations directly in the optical domain. Thus they become a building block to create switching elements in on-chip optical interconnection networks, which promise to overcome some of the limitations of current electronic networks. However, the peculiar asymmetric power losses of microring resonators impose new constraints on the design and control of on-chip optical networks. In this work, we study the design of multistage interconnection networks optimized for a particular metric that we name the degradation index, which characterizes the asymmetric behavior of microrings. We also propose a routing control algorithm to maximize the overall throughput, considering the maximum allowed degradation index as a constraint.

Multi-MetaRing Protocol: Fairness in Optical Packet Ring Networks

We focus on metropolitan area networks operating in packet mode and exploiting a single-hop wavelength division multiplexing (WDM) architecture. First, we briefly describe a specific slotted WDM optical network, based on a folded bus topology. Then, we address the fairness problem arising in this architecture and propose an extension of the MetaRing protocol to a WDM scenario. Two possible strategies are defined and analyzed. Finally, we show that both fair access and high aggregate network throughput can be achieved by properly handling node access through all WDM channels.

OPN03-1: Multi-Fasnet Protocol: Short-Term Fairness Control in WDM Slotted MANs

Single-hop wavelength division multiplexing (WDM) ring networks operating in packet mode are a promising architecture for the design of innovate metropolitan area networks. They allow a cost-effective design, with a good combination of optical and electronic technologies, while supporting features like restoration and reconfiguration that are essential in any metropolitan scenario. In this article, we address the fairness problem in a slotted WDM optical network. We introduce the multi-fasnet fairness protocol, we discuss its limitations and we propose an extension, based on a dynamic strategy, that achieves high aggregate network throughput, throughput fairness, and bounded and fair access delays.

RateOptimal scheduling schemes for asynchronous InputQueued packet switches

The performance of input-queued packet switches critically depends on the scheduling scheme that connects the input ports to the output ports. We show that, when packets are switched asynchronously, simple scheduling schemes where contention is solved locally at each input or output can achieve rate optimality, without any speed-up of the internal transmission rate.

Optical interconnection architectures based on microring resonators

Microring resonators are an interesting device to build integrated optical interconnects, but their asymmetric loss behavior could limit the scalability of classical optical interconnects. We present new interconnects able to increase scalability with limited complexity.

An Optical Interconnection Architecture for Large Packet Switches

The design of switching architectures for todays telecommunication networks needs to consider the limits imposed by electronic technology; in particular, it must take into account power consumption and dissipation, as well as power supply and footprint requirements. Currently, optical technology is exploited mainly for transmission over optical links requiring large bandwidth-distance products; however, many researchers and switch architects believe that its introduction for switching functions can overcome most of the current design limits. Since many years, the research community has been studying not only solutions that make use of optics inside electronic switches but that also switching architectures that implement optical switching without any need of optoelectronic conversion. In this paper, we propose an optical switching architecture based on a WDM (Wavelength Division Multiplexing) optical bus, aiming at interconnecting electronic line cards inside packet switches. In particular, the use of distributed packet scheduling techniques is addressed and its performance is discussed.

The role of Arrayed Waveguide Gratings in energy-efficient optical switching architectures

The power consumption of large IP routers is increasing too fast with the increase of Internet traffic. This power consumption can be reduced if Optical Switching Fabrics (OSFs) are used instead of electronic backplanes and interconnects. And Arrayed Waveguide Gratings (AWGs) exhibit interesting properties for the design and implementation of OSFs. The paper studies how OSFs based upon AWGs scale in terms of aggregate switching capacity and power consumption.