Maurizio Casoni

Transparent optical packet switching: the European ACTS KEOPS project approach

This paper reviews the work carried out under the European ACTS KEOPS (KEys to Optical Packet Switching) project, centering on the definition, development and assessment of optical packet switching and routing networks capable of providing transparency to the payload bit rate. The adopted approach uses optical packets of fixed duration with low bit rate headers to facilitate processing at the network/node interfaces. The paper concentrates on the networking concepts developed in the KEOPS project through a description of the implementation issues pertinent to optical packet switching nodes and network/node interfacing blocks, and consideration of the network functionalities provided within the optical packet layer. The implementation, from necessity, relies on advanced optoelectronic components specifically developed within the project, which are also briefly described.

Packet optical networks for high-speed TCP-IP backbones

This article presents a new proposal for TCP-IP backbone implementation based on optical packet switching technology. The proposed network architecture merges the flexibility in resource management of packet switching with the high capacity offered by full optical technology.

Integration of satellite and LTE for disaster recovery

Wireless communications are critical for public protection and disaster relief (PPDR) professionals during the emergency operations that follow natural or man-made disasters, scenarios in which both commercial and dedicated terrestrial networks often fail to provide the necessary support. The reason is threefold: they simply get destroyed by the disaster, they cannot sustain the sudden surge of network demand or they fail to deliver the necessary bandwidth and/or other QoS guarantees. Because LTE is expected to become the main wireless technology for broadband communication, a lot of studies have been devoted to assess its compliance for PPDR purposes and to find suitable architectural solutions able to meet mission-critical requirements. This approach is surely worthy, but it is based on the assumption that infrastructure-based terrestrial systems are reliable. As a consequence, in worstcase emergency scenarios appropriate guarantees can be provided only in the hypothesis of huge investment costs. Recent developments in satellite technologies are bringing the availability of non-terrestrial high performance channels, with better properties when comparing to LTE for what regards availability and reliability. On this basis, the paper proposes a network architecture based on the integration of satellite and LTE networks for both infrastructure-based and infrastructure-less scenarios. The proposal aims to provide field operators and people in distress with transparent accessibility, coverage guarantees and broadband performance when terrestrial infrastructures are lacking, and to expand their coverage, capacity and resilience otherwise.

Energy-Efficient Elastic Optical Interconnect Architecture for Data Centers

To address the urgent need for high-capacity, scalable and energy-efficient data center solutions, we propose a novel data center network architecture realized by combining broadcast-and-select approach with elastic channel spacing technology. We demonstrate that the proposed architecture is able to scale efficiently with the number of servers and offers lower energy consumption at a competitive cost compared to the existing solutions.

Performance and Power Consumption Analysis of a Hybrid Optical Core Node

Hybrid optical switching (HOS) is a switching paradigm that aims to combine optical circuit switching, optical burst switching, and optical packet switching on the same network. This paper proposes a novel integrated control plane for an HOS core node. The control plane makes use of a unified control packet able to carry the control information for all the different data formats and employs an appropriate scheduling algorithm for each incoming data type. Three possible node architectures are presented and an analytical model is introduced to analyze their power consumption. Also, the concept of increase in power efficiency is introduced to compare the considered architectures. The performance and power consumption analysis of the node have been carried out through the use of a simulation model developed specifically for the scope. The obtained results show the effectiveness of HOS networks.

Admission control in T/CDMA systems supporting voice and data applications

This paper analyses the behavior of two hybrid time-code division multiple-access (T/CDMA) architectures on the up-link of a macrocellular mobile radio system. For the examined schemes two categories of users-voice and data-share the domain of available resources, made up of time slots and codewords, through two alternative assignment strategies. Both solutions attribute voice users one single resource pair, i.e., one time slot and a single code to employ on that time slot, but differ in the way data users requests are accommodated: they are either simultaneously granted several codes over the same time slot or are assigned a single code over several distinct time slots. Call admission control is performed by a channel assignment algorithm which dynamically attributes resources only if specified levels of transmission quality are met on the radio channels. The blocking and the outage probability of the two classes of users are determined and compared, showing that one of the proposed schemes exhibits better performance and allows to satisfyingly serve a significant percentage of data users.

On the performance of early packet discard

In a previous paper, one of the authors gave a worst case analysis for the early packet discard (EPD) technique for maintaining packet integrity during overload in ATM switches. This analysis showed that to ensure 100% goodput during overload under worst case conditions requires a buffer with enough storage for one maximum length packet from every active virtual circuit. This paper refines that analysis, using assumptions that are closer to what we expect to see in practice, and examines how EPD performs when the buffer is not large enough to achieve 100% goodput. We show that 100% goodput can be achieved with substantially smaller buffers than predicted by the worst case analysis, although the required buffer space can be significant when the link speed is substantially higher than the rate of the individual virtual circuits. We also show that high goodputs can be achieved with more modest buffer sizes, but that EPD exhibits anomalies with respect to buffer capacity, in that there are situations in which increasing the amount of buffering can cause the goodput to decrease. These results are validated by comparison with simulation.

Hybrid optical switching for data center networks

Current data centers networks rely on electronic switching and point-to-point interconnects. When considering future data center requirements, these solutions will raise issues in terms of flexibility, scalability, performance, and energy consumption. For this reason several optical switched interconnects, which make use of optical switches and wavelength division multiplexing (WDM), have been recently proposed. However, the solutions proposed so far suffer from low flexibility and are not able to provide service differentiation. In this paper we introduce a novel data center network based on hybrid optical switching (HOS). HOS combines optical circuit, burst, and packet switching on the same network. In this way different data center applications can be mapped to the optical transport mechanism that best suits their traffic characteristics. Furthermore, the proposed HOS network achieves high transmission efficiency and reduced energy consumption by using two parallel optical switches. We consider the architectures of both a traditional data center network and the proposed HOS network and present a combined analytical and simulation approach for their performance and energy consumption evaluation. We demonstrate that the proposed HOS data center network achieves high performance and flexibility while considerably reducing the energy consumption of current solutions.

A satellite based system for managing crisis scenarios: The E-SPONDER perspective

This paper presents the work that is currently performed in the E-SPONDER (FP7–242411) project. E-SPONDER is a project co-funded by the European Commission under its Security Program. E-SPONDER is a suite of real-time data-centric technologies that will provide information and communication support to first responders which act during normal and abnormal events (crises). It will investigate the use of interoperable communications that will facilitate the uninterruptible link between the first responders at the operations theatre and the crisis managers at the Emergency Operations Center. To achieve that, a novel architecture is introduced that brings satellite communications in the spotlight of effective first response work. The paper demonstrates the way satellite communications will be integrated to the E-SPONDER system in order to ensure always-on communications and data exchange.

A low-latency and high-throughput scheduler for emergency and wireless networks

Providing QoS guarantees, boosting throughput and saving energy over wireless links is a challenging task, especially in emergency networks, where all of these features are crucial during a disaster event. A common solution is using a single, integrated scheduler that deals both with the QoS guarantees and the wireless link issues. Unfortunately, such an approach is not flexible and does not allow any of the existing high-quality schedulers for wired links to be used without modifications. We address these issues through a modular architecture which permits the use of existing packet schedulers for wired links over wireless links, as they are, and at the same time allows the flexibility to adapt to different channel conditions. We validate the effectiveness of our modular architecture by showing, through formal analysis as well as experimental results, that this architecture enables us to get a new scheduler with the following features, by just combining existing schedulers: execution time and energy consumption close to that of just a Deficit Round Robin, accurate fairness and low latency, possibility to set the desired trade-off between throughput-boosting level and granularity of service guarantees, by changing one parameter. In particular, we show that this scheduler, which we named Highth-roughput Twin Fair scheduler (HFS), outperforms one of the most accurate and efficient integrated schedulers available in the literature.