A. Stavdas

Dimensioning the Future Pan-European Optical Network With Energy Efficiency Considerations

This paper studies the overall energy consumption of a pan-European optical transport network for three different time periods: today and in five and ten years from now. In each time period the pan-European network was dimensioned using traffic predictions based on realistic data generated by the optical networking roadmap developed in the framework of the European project Building the Future Optical Network in Europe-BONE. A wavelength routed wavelength division multiplexed optical network based on either transparent or opaque node architectures was examined considering exclusively either 10 Gbit/s or 40 Gbit/s per channel data rates. The results manifest that transparent optical networking technologies are expected to provide significant energy savings of the order of 35% to 55%. It was also shown that the migration towards higher data rates, i.e., from 10 Gbit/s to 40 Gbit/s, is assisting in improving the overall energy efficiency of the network.

Optical packet routers: how they can efficiently and cost-effectively scale to petabits per second

Todays data-centric networks are becoming progressively dynamic with respect to the transported traffic volume, to the spatial and temporal variations of traffic patterns, and to the subsequent interconnection request patterns. Optical packet routers (OPRs) aim to provide a viable answer to these requirements by rendering the optical layer adaptable, reconfigurable at will, and cost-effective by means of statistical multiplexing of the network resources while satisfying end-to-end quality-of-service requirements. We study the role of OPRs in two different network approaches: an OPR adopting the legacy of a telecommunication solution and a solution pertinent to the role and the functionality of an IP world. To benchmark the two scenarios, a multilayer, multigranular OPR architecture is presented and its potential to cost-effectively scale toward petabit-per-second throughput is justified by means of physical layer performance and power consumption estimations for each case. Furthermore, the blocking and frame-loss performance of the proposed OPRs is presented, proving the viability of the proposed solutions.

Integrated design and operation of a transparent optical network: a systematic approach to include physical layer awareness and cost function [Topics in Optical Communications]

The manner and exact timing of the evolution of the widely used DWDM infrastructure to a transparent optical network is judged on economic circumstances and network performance. In this context this article elaborates on a methodology developed within the Project 1ST NOBEL, for integrating cost functions and other design constraints into the planning of a DWDM network while considering this evolution perspective to a transparent optical network. This systematic approach builds upon the experience of static network design and is substantiated by specific examples in this article

Cross Layer Routing in Transparent Optical Networks

New algorithmically simplified WRA that incorporate physical layer criteria in the path establishment procedure are suggested and applied in the Deutsche-Telecom network. Their blocking performance superiority and physical performance guarantee are discussed.

Optical Wavelength and Waveband Converters

Wavelength conversion has been acknowledged as one of the most significant optical processing functions and various papers have been involved with investigating methods of translating very high bit-rate data into other wavelengths. This paper will give an overview of the recent advances in the area, with emphasis on methods that can be used as both wavelength and waveband converters, which can be used at higher bit rates without any configuration changes and are integratable and hence compact solutions. Four-wave mixing in SOAs is one of these techniques and we will elaborate on particulars of this technique. Switch architectures that benefit from wavelength and waveband conversion are presented

Hybrid burst/packet switching architectures from IP NOBEL

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 todays requirements for Tb/s core networks.

Power considerations towards a sustainable Pan-European network

Energy savings are observed and quantified in the Pan-European network using transparent optical network technology. The network was dimensioned, using realistic traffic predictions of the optical networking roadmap of the European project BONE.

Single-layer multigranular optical cross-connect architecture with conversion capability and enhanced flexibility

Feature Issue on Waveband Switching, Routing, and GroomingThe rapid advances in WDM technology are expected to bring about tremendous growth in the size of optical cross connects (OXCs). In this context, multigranular OXCs (MG-OXCs) have been suggested as a means of reducing the amount of equipment required. Here we expand the concept of MG-OXCs to include optical packet granularity and review the key building blocks for the advent of MG-OXCs. A single-layer MG-OXC is suggested that offers enhanced flexibility with respect to other single-layer concepts, conversion capability, and good physical performance. Concatenation performance is analytically investigated.

All-optical packet synchronizer for slotted core/metropolitan networks

In the framework of synchronous optical packet networks, a cost-effective all-optical synchronizer is an important building block to effectively switch the packets through an optical router. In striking difference to its time-division multiplexing-based electronic counterparts requiring bit level synchronization, an optical router can operate effectively with a much coarser synchronization at packet level. Such a synchronizer is proposed, which can compensate for the time variations between packets transported over several wavelengths. The requested synchronization is achieved with a resolution that is a fraction of the packet duration, which is a process that is adequate to compensate for the delays due to thermal variations between the transport fibers. Because this WDM synchronizer is constructed using slowly reconfigurable and mainly passive components, it is potentially a cost-effective solution. The principle of operation of this synchronizer is described in the context of synchronous slotted optical networks; the functionality of the various building blocks is analyzed, and practical implementation issues of various subsystems for a 80 Gbit/s synchronizer are discussed. Finally, an experimental validation of the proposed synchronizer is made demonstrating the viability of the method.

PLI-Aware Routing in Regenerated Mesh Topology Optical Networks

Wavelength routing algorithms (WRAs) aware of Physical layer impairments (PLIs) have been proposed in order to manage the establishment of optical paths in wavelength-switched optical networks. However, if optical nodes incorporate regenerators/wavelength converters, PLI-aware WRAs should be devised in order to incorporate error accumulation in the signal in the PLI estimation and relaxation of the wavelength continuity constraint in the path calculation. In this paper, we utilize a new bit error rate performance estimation in combination with the PLI-aware WRA in order to systematically investigate the role of regeneration and wavelength conversion in optical networks. Based on the outcomes of the study, we also propose a path establishment algorithm that is based on the “instant” physical properties of the path and can dynamically adapt to the network state. This is proven beneficial as far as the blocking performance is concerned as it circumvents the weaknesses that appear in the traditional shortest distance path establishment algorithms in a PLI-aware environment that operates without the wavelength continuity constraint.