Nuova ricerca

Maurizio CASONI

Professore Associato presso: Dipartimento di Ingegneria "Enzo Ferrari"


Home | Curriculum(pdf) | Didattica |


Pubblicazioni

2020 - Application-Level Performance of IEEE 802.11p in Safety-Related V2X Field Trials [Articolo su rivista]
Klapez, Martin; Grazia, Carlo Augusto; Casoni, Maurizio
abstract


2020 - BBR+: Improving TCP BBR Performance over WLAN [Relazione in Atti di Convegno]
Grazia, C. A.; Patriciello, N.; Klapez, M.; Casoni, M.
abstract

This paper shows the inefficiency of TCP BBR in exploiting the Wi-Fi bandwidth. This limitation of BBR has been observed with both IEEE 802.1ln and IEEE 802.11ac, where the mechanism of frame aggregation is used to boost the throughput of data transmission. In the last years, many TCP variants have been introduced to limit the bufferbloat phenomena and bound the latency, through a reduction of the queue backlog injection rate. However, this mechanism impacts on the Wi-Fi frame aggregation logic, impeding TCP congestion controls to reach the full throughput potential of a Wi-Fi interface. While this problem can be solved with TCP CUBIC allowing the sender node to enqueue more packets, for TCP BBR the fix is not the same, as it has a customized pacing algorithm. With this contribution, we propose BBR+, a new BBR version that allows to fine tune the congestion control pace, achieving 6 times more throughput over IEEE 802.1ln channels and 16 times more throughout over IEEE 802.11ac channels, at the cost of an increased latency that is however always less than the latency obtainable with TCP CUBIC.


2020 - BBRp: Improving TCP BBR Performance over WLAN [Articolo su rivista]
Grazia, C. A.; Klapez, M.; Casoni, M.
abstract

This paper shows the inefficiency of TCP BBR in exploiting the Wi-Fi bandwidth. This limitation of BBR has been observed with both IEEE 802.11n and IEEE 802.11ac, where the mechanism of frame aggregation is used to boost the throughput of data transmission. In the last years, many TCP variants have been introduced to limit the bufferbloat phenomena and bound the latency through a reduction of the queue backlog injection rate. However, this mechanism impacts on the Wi-Fi frame aggregation logic, impeding TCP congestion controls to reach the full throughput potential of a Wi-Fi interface. While this problem can be solved with TCP Cubic by allowing the sender node to enqueue more packets, for TCP BBR the fix is not the same, as it has a customized pacing algorithm. With this contribution we propose BBRp, a new BBR version that allows for fine-tuning the congestion control pace, achieving between four and six times more throughput over IEEE 802.11n and IEEE 802.11ac channels, at the cost of an increased latency that is however always less than the latency obtainable with loss-based TCP congestion controls.


2020 - IRONMAN: Infrastructured RSSI-based opportunistic routing in mobile adhoc networks [Relazione in Atti di Convegno]
Grazia, C. A.; Klapez, M.; Casoni, M.
abstract

V2X technologies are based on heterogeneous and safety-related applications that rely on broadcast messages, which are typical in V2V communications, and to unicast messages, which are, instead, typical in V2I/I2V communications. To ease unicast communications from the infrastructure to the vehicle, like rescue operations, addressing the challenging routing aspect for VANETs, we designed an Infrastructured RSSI-based Opportunistic routiNg algorithm for Mobile Adhoc Networks (IRONMAN), also focusing on the energy consumption of the solution developed. IRONMAN takes opportunistic routing decisions based on the RSSI calculated by the Road-Side Units (RSUs), instead of the classical GPS-based solutions. Through a real testbed, we demonstrate that IRONMAN outperforms standard Linux-based routing solutions for ad-hoc networks, like BATMAN and HWMP, providing almost optimal goodput without adding any overhead related to the routing decisions.


2020 - Minimization of IEEE 802.11p Packet Collision Interference through Transmission Time Shifting [Articolo su rivista]
Klapez, Martin; Grazia, Carlo Augusto; Casoni, Maurizio
abstract


2019 - Emergency Networks and Future Public Safety Systems [Articolo su rivista]
Casoni, M.; Guo, S.; Benslimane, A.
abstract


2019 - IEEE 802.11p field trials on interference minimization for safety-related V2X applications [Relazione in Atti di Convegno]
Klapez, M; Grazia, C. A.; Casoni, M
abstract

In this work, we focus on the well-known hiddenterminal problem applied to the IEEE 802.11p context, from aninfrastructure-centric point of view (I2V). The problem occursin scenarios where two nodes are out of each other’s rangewhile being independently able to communicate with a thirdthat, intuitively speaking, is positioned in the middle of theformer two. If the two nodes transmit to the third at the samefrequency and at the same time, though not exactly the samesignal, the third would be unable to identify the two sourcesignals and, therefore, would suffer from interference. Althoughthe occurrence of this problem may be unlikely in I2V practice,certain applications, such as road safety, require the problemto be addressed anyhow. This article shows the outcomes offield trials conceived to experience first-hand the occurrence ofthe issue in IEEE 802.11p networks, experiment with differentinterference management techniques, and design or select theoptimal approach to minimize interference. Results unequivocallyattest that, in this context, an ad-hoc Time-Division MultipleAccess (TDMA) approach provides the best guarantees in anycondition. It is also shown how, on the other hand, the commonmethod of using the Request To Send/Clear To Send (RTS/CTS)protocol to prevent the issue in unicast scenarios may result ina disappointing performance, due to the nature of safety-relatedI2V communications that employ short packets to be deliveredwith minimum latency.


2019 - IEEE 802.11p under congestion in an Infrastructure-to-Vehicle communication approach [Relazione in Atti di Convegno]
Klapez, M; Grazia, C. A.; Rold, L.; Casoni, M
abstract

Possible applications of the so-called Intelligent Transportation Systems, or connected vehicles, range from critical to trivial and comprise road safety, traffic and transportation efficiency, and infotainment. The networks underlying these applications are under development and test, but few works are available in the literature that present results from real testbeds. This article is about the performance of IEEE 802.11p networks under congestion in vehicular environments, analysed from an infrastructure-centric point of view. In particular, as no assumptions are made about the communication behavior of vehicles, the paper is a starting point in answering the question of how much guarantees the standardized technologies are able to provide in worst-case scenarios of network congestion. An IEEE 802.11p first physical testbed has been developed, and it has been used to perform tests on latency, bandwidth, and packet losses with real network traffic. Although to answer the question completely tests with farther distances and different devices have to be made, these first results appear promising. The RoadSide Units ability to deliver critical messages does take a hit during signaling storms generated by vehicles, but due to the small size and connection-less nature of the packets expected to be employed, some bandwidth remains available, although some redundancy mechanism, carefully designed, might be needed to overcome relatively high packet loss ratios.


2019 - Next generation emergency services based on the Pan-European Mobile Emergency Application (PEMEA) protocol: Leveraging mobile positioning and context information [Articolo su rivista]
Sedlar, U.; Winterbottom, J.; Tavcar, B.; Sterle, J.; Cijan, J.; Volk, M.; Casoni, M.
abstract

In this paper, we analyze requirements of next generation 112 emergency services in the era of ubiquitous mobile devices and sensors and present the design, implementation, and piloting results of our testbed, which was developed within the H2020 project NEXES. The system leverages a multihop location-aware PEMEA routing network that finds the geographically closest responsible public service answering point (PSAP) and supports cross-border application roaming. Our reference mobile implementation utilizes multiple device and network-based positioning technologies, which, combined, both outperform traditional cell-tower based positioning and provide a means for detecting fraudulent calls. The system is extensible and can establish a variety of communication channels after the initial emergency session is set up; we demonstrate this with an interoperable WebRTC-based video call. The obtained results demonstrate the viability and flexibility of PEMEA-based over-the-top emergency services, show high user acceptance when comparing them with existing solutions, and thus pave the road for further rollout of such systems.


2019 - Processing and Communication Delays in EWS: On the Performance of the Earthcloud Prototype [Articolo su rivista]
Klapez, M.; Grazia, C. A.; Casoni, M.; Zennaro, S.; Cozzani, M.
abstract

A Seismic Alert System (SAS), also called Earthquake Warning System (EWS) or Earthquake Early Warning System (EEW or EEWS), represents one of the most important measures that can be taken to prevent and minimize earthquake damage. These systems are mainly used to detect P-waves and the faster seismic waves and to subsequently trigger an alarm about the incoming S-waves, the slower and most dangerous seismic waves. In some cases, distributed systems are also able to alert some locations before the impending P-waves strike them. This paper presents Earthcloud, a cloud-based SAS that aims to provide all the former capabilities while retaining financial accessibility. Earthcloud first results, generated from four months of data acquisition, are compared with those coming from other systems. In particular, the paper focuses on processing and communication delays, showing how the Earthcloud new detection strategy may minimize delays. Although a thorough test campaign with more sensor nodes is needed to assess performance reliably, especially for highly dense urban scenarios, initial results are promising, with total latencies for Earthcloud always kept under the 1-second mark, despite being at the expense of solid magnitude estimation.


2019 - Sensing Coverage Algorithm of Sparse Mobile Sensor Node with Trade-Off between Packet Loss Rate and Transmission Delay [Articolo su rivista]
Zhao, K.; Chen, Y.; Lu, S.; Liu, B.; Ren, T.; Wang, Z.; Casoni, M.
abstract

To solve the problem of sensing coverage of sparse wireless sensor networks, the movement of sensor nodes is considered and a sensing coverage algorithm of sparse mobile sensor node with trade-off between packet loss rate and transmission delay (SCA-SM) is proposed. Firstly, SCA-SM divides the monitoring area into several grids of same size and establishes a path planning model of multisensor nodes' movement. Secondly, the social foraging behavior of Escherichia coli in bacterial foraging is used. A fitness function formula of sensor nodes' moving paths is proposed. The optimal moving paths of all mobile sensor nodes which can cover the entire monitoring area are obtained through the operations of chemotaxis, replication, and migration. The simulation results show that SCA-SM can fully cover the monitoring area and reduce the packet loss rate and data transmission delay in the process of data transmission. Under certain conditions, SCA-SM is better than RAND-D, HILBERT, and TCM.


2019 - Textile multiantenna technology and relaying architectures for emergency networks [Articolo su rivista]
Crespo-Bardera, E.; Vega Delgado, A.; Garrido Martin, A.; Fernandez-Duran, A.; Sanchez-Fernandez, M.; Casoni, M.
abstract

Every year around 200 million people are affected by hazards of different nature. In most of these situations public protection and disaster relief personnel are usually the first responders to provide help. To provide differential relief coverage in these scenarios, novel communication and network functionalities are being demanded, relegating today's narrowband private radio (PMR) emergency systems to the background. These are data-support, increased coverage, broadband communication, and high reliability which will be addressed by novel communication technologies such as Long Term Evolution (LTE), LTE Advanced-pro, and future 5G. In this work we tackle two key technological solutions for future emergency communication networks such as an architecture based on relay nodes and enhanced user equipment by means of multiple-input-multiple-output (MIMO) techniques.


2019 - Tool for Recovering after Meteorological Events Using a Real-Time REM and IoT Management Platform [Articolo su rivista]
Hervis Santana, Y.; Plets, D.; Martinez Alonso, R.; Guillen Nieto, G. A.; Garcia Fernandez, N.; Deruyck, M.; Joseph, W.; Casoni, M.
abstract

This paper is the design of a Radio Environment Map (REM) with a real-time tool to sense the radiofrequency spectrum and optimally places with Surrogate Modelling and Sequential Experimental Design tools a total of 72 SDR sensors in the selected area, using LoRa and/or NB-IoT technologies for networking. It permits the regulatory body to check the correct use of the assigned spectrum and constitutes a communication alternative in case of a catastrophic event, such as a hurricane or an earthquake, where radio and TV broadcasting play an important role in keeping people informed after such meteorological event. The radiobroadcast services use large antennas and high towers, making them vulnerable to such events. Regardless of the chosen technology, the IoT monitoring network will be more robust, since it uses small antennas and lower towers, and often a given area is covered by multiple base stations. The tool can be used to deploy new services in the nonserved area (e.g., 4G in the 700 MHz band at a lower cost or using TVWS techniques to provide communications and internet connection) and optimal interference management.


2019 - Towards Backpressure Routing in Wireless Mesh Backhauls for Dense LTE Deployments [Relazione in Atti di Convegno]
Patriciello, N.; Nunez-Martinez, J.; Baranda, J.; Casoni, M.; Mangues-Baffalluy, J.
abstract

Future 5G networks will rely on heterogeneousdeployment of micro eNodeBs, and is expected that wirelesstransport interfaces, deployed together with each eNodeB, willprovide high-speed backhaul connectivity through the possibilityto create an ad-hoc wireless mesh between the deployed microeNodeBs. Therefore, the backhaul routing strategy will play afundamental role in exploiting the backhaul resources. In thiscontext, we aim to investigate the advantages and limitationsof qualitatively different backhaul routing strategies as UEsdownload TCP and UDP content. In this paper, we comparea backpressure-based strategy that takesper-packetorper-flowbasis (BP-MR) and traditional single path routing (OLSR). Ns-3simulations show that theper-packetBP-MR variant enhancesUDP performance by circumventing congestion but degradesTCP because of reordering. Theper-flowBP-MR variant mini-mizes retransmissions by limiting the excessive reordering, andoutperforms OLSR performance for both UDP backhaul trafficand TCP traffic.


2019 - Transmission Control Protocol and Active Queue Management together against congestion: cross-comparison through simulations [Articolo su rivista]
Grazia, Carlo Augusto; Patriciello, Natale; Klapez, Martin; Casoni, Maurizio
abstract

Most Internet traffic is carried by the Transmission Control Protocol (TCP) nowadays, even in the case of real-time services. Detecting and mitigating the congestion is one of the primary tasks of this protocol, in fact, different TCP versions are defined by their congestion control algorithms. Furthermore, Active Queue Management (AQM) algorithms share the same goal of congestion mitigation with TCP; in particular, the most efficient congestion control occurs when AQM and TCP work together. This paper presents a brief survey and a cross-comparison of the latest and most important TCP and AQM variants, then provides an evaluation of a different kind of performance on the ns-3 network simulator over various types of environments (multiple Round Trip Time, long delay, different congestion levels, etc.). In any shared bottleneck, the choice of the TCP-AQM couple to adopt is crucial. We will show that the results are not univocal and the “one size fits all” solution does not exist. Moreover, the proper couple depends on the performance that we want to boost and on the environment that we have to deal with.


2018 - A hybrid algorithm to combine redundancy and concurrency in virtual network resource pooling [Articolo su rivista]
Klapez, M.; Grazia, C. A.; Casoni, M.
abstract

Emergency scenarios pose significant hurdles to wireless communications, especially when these are performed through terrestrial cellular networks. This is because network infrastructures can be damaged, or the sudden surge of network demand can cause unbearable network congestion. Unfortunately, public safety operators employ terrestrial cellular networks to perform data communications and are therefore at risk of being unable to effectively operate in critical situations. Virtual network resource pooling is a software-defined networking (SDN)-based network framework that allows collaborative hosts to pool together their network channels to provide connectivity despite the sudden unavailability of network paths or to compensate for high degrees of packet losses. Once hosts’ resources are pooled, a dispatching algorithm on the SDN controller is required to enforce a proper policy of packets distribution. This paper presents a dispatching algorithm that is designed to provide fast and reliable transmissions despite lossy and unreliable channels. It works by introducing the minimum amount of packet redundancy that is needed to obtain a packet delivery probability given as a parameter and by using the remaining network resources to augment transfer goodput. Emulation results confirm that with respect to policies that selectively aim to improve goodput or to introduce packet redundancy, this hybrid algorithm can compensate for high packet loss ratios and improve goodput at the same time.


2018 - Achieving a High Throughput and a Low Latency through a Modular Packet Scheduler [Articolo su rivista]
Casoni, M.; Grazia, C. A.; Valente, P.
abstract

Providing QoS guarantees in a wireless environment is a challenging task because of the idiosyncrasies of the wireless media. State-of-the-art solutions for QoS provisioning over wireless links are based on cross-layering packet schedulers that deal both with the QoS guarantees and the wireless link issues. Unfortunately, such an approach is not flexible and requires technology-dependent solutions. To address these issues, we present a modular architecture which permits the use of existing high-performance packet schedulers for wired links over generic wireless technologies, as they are, and at the same time allows the flexibility to adapt to different channel conditions. We validate the effectiveness of our modular solution through a formal analysis. We also present high-throughput twin fair scheduler (HFS), a novel packet scheduler based on the modular architecture. HFS has constant execution time, accurate fairness, and low latency.


2018 - Adapting TCP Small Queues for IEEE 802.11 Networks [Relazione in Atti di Convegno]
Grazia, C. A.; Patriciello, N.; Høiland-Jørgensenz, T.; Klapez, M.; Casoni, M.; Mangues-Bafalluy, J.
abstract

In recent years, the Linux kernel has adopted an algorithm called TCP Small Queues (TSQ) for reducing queueing latency by controlling buffering in the networking stack. This solution consists of a back-pressure mechanism that limits the number of TCP segments within the sender TCP/IP stack, waiting for packets to actually be transmitted onto the wire before enqueueing further segments. Unfortunately, TSQ prevents the frame aggregation mechanism in the IEEE 802.11n/ac standards from achieving its maximum aggregation, because not enough packets are available in the queue to build aggregates from, which severely limits achievable throughput over wireless links. This paper demonstrates this limitation of TSQ in wireless networks and proposes Controlled TSQ (CoTSQ), a solution that improves TSQ so that it controls the amount of data buffered while allowing the IEEE 802.11n/ac aggregation logic to fully exploit the available channel and achieve high throughput. Results on a real testbed show that CoTSQ leads to a doubling of throughput on 802.11n and up to an order of magnitude improvement in 802.11ac networks, with a negligible latency increase.


2018 - Energy Savings of Sleep Modes enabled by 5G Software-Defined Heterogeneous Networks [Relazione in Atti di Convegno]
Klapez, M.; Grazia, C. A.; Casoni, M.
abstract

The current base station centric cellular network architecture hinders the implementation of effective sleep techniques, often resulting in energy-inefficient mobile networks. The efforts towards 5G and network densification, however, open new possibilities and may, at last, allow the integration of sleep modes without any QoS degradation. In this paper, we consider heterogeneous networks in which data and control planes are split and independent, referred to as SDHN. We present an energy consumption metric that can be used to evaluate the radio access power consumption and the associated energy efficiency of these networks. Concerning other metrics in literature, the proposal accounts for both the coverage area as well as the traffic load, and it is relatively simple to use. The proposed metric is applied to evaluate the power consumption performance of an LTE SDHN in an urban indoor scenario. Results confirm that sleep modes in such architectures can effectively cut power consumption and improve energy efficiency while preserving QoS.


2018 - First Experiences with Earthcloud, a Low-Cost, Cloud-Based IoT Seismic Alert System [Relazione in Atti di Convegno]
Klapez, M.; Grazia, C. A.; Zennaro, S.; Cozzani, M.; Casoni, M.
abstract

A Seismic Alert System (SAS) is one of the most important measures that can be taken to prevent and minimize earthquake damage. The role of a SAS is to detect as soon as possible an earthquake in progress and to then immediately alert about the impending earthquake waves all locations in danger. Clearly, to be of any utility, the communication of the alarm has to be transmitted way faster than the propagation speed of the earthquake waves. This paper presents the rationale, setup and first results of a deployed Earthcloud prototype, an experimental SAS designed to be low-cost, low-power, and cloudbased. Earthcloud is devised to alert locations that are not too close yet not too far from the earthquake epicenter, i.e., those that can benefit from an alarm received from a few seconds to tens of seconds earlier. The system has been designed to leverage existing Internet infrastructures in order to perform both computation and communication in the cloud, minimizing costs and maximizing communication speed and deployment ease. Data harvested by Earthcloud has been cross-referenced with data from the Italian National Institute of Geophysics and Volcanology and, although still in a prototype stage, the first results indicate that the system can correctly detect earthquakes.


2018 - Quantifying Sleep-Related Energy Savings in Indoor LTE HetNets Radio Access [Relazione in Atti di Convegno]
Klapez, M.; Grazia, C. A.; Casoni, M.
abstract

While Sleep techniques show great promises in reducing the energy consumption of mobile networks, the necessity of providing “always-on” services with current cellular architectures significantly hinders the introduction of effective Sleep modes. As the process of network densification goes forward, it is paramount to lower to a minimum the additional energy consumption required by the deployment of more and more network sites. Fortunately, the deployment of Heterogeneous Networks opens new possibilities for the integration of simpler and highly effective Sleep technologies. In this paper, we evaluate and quantify the energy savings attainable by the latest Power Modulation and Sleep modes in a Heterogeneous LTE Network deployed to serve a traffic-intensive urban office area. Power consumption figures are based on those of real cells currently available on the market. Results indicate that the combination of Power Modulation and Sleep techniques is able to cut in half the energy required by the modeled Heterogeneous Network and that Sleep modes, in particular, can be the most beneficial.


2018 - The Bufferboost Effect: when Drops and Redundancy boost the Throughput [Relazione in Atti di Convegno]
Grazia, C. A.; Klapez, M.; Casoni, M.
abstract

In this paper, we present and characterize a phenomenon that arises when network congestion is met with packet redundancy at a distributed bottleneck. Congestion typically causes packet drops at the queueing level, especially when Active Queue Management techniques are employed to mitigate the bufferbloat effect. Redundancy may be present in the form of packet replication over different paths, as a solution to increase network resilience and network availability guarantees. When both network congestion and packet redundancy are in place, a counterintuitive throughput-boosting effect may originate from them. We named this phenomenon bufferboost, for the key role played by packet drops introduced to avoid bufferbloat effects. The contributions of this paper are the definition of the bufferboost phenomenon, its modelling through a mathematical upper bound formulation, its isolation in an emulated environment for reproducibility and its validation through an extensive numerical evaluation that also verifies the introduced model. Results show that bufferboost is a favorable side effect able to boost network throughput.


2017 - A Cross-Comparison between TCP and AQM Algorithms: which is the Best Couple for Congestion Control? [Relazione in Atti di Convegno]
Grazia, CARLO AUGUSTO; Patriciello, Natale; Klapez, Martin; Casoni, Maurizio
abstract

Current Internet traffic is carried mainly by the Transmission Control Protocol (TCP), and the performance of the Internet depends strongly on how well TCP works. Detecting and mitigating the congestion is one of the main tasks of this protocol, in fact, different TCP versions are defined by their congestion control algorithm. Also, Active Queue Management (AQM) algorithms share the same goal of congestion mitigation with TCP, in particular, the most effective congestion control occurs when AQM and TCP work together. This paper presents a brief survey and a cross-comparison of the latest and most important TCP and AQM variants, then provides an evaluation of a different kind of performance (multiple Round-Trip Time, long delay, different congestion level, etc.) on the ns-3 network simulator over various types of environments. In a shared bottleneck, the choice of the TCP-AQM couple to adopt is crucial; we show that the results are not univocal, the “golden couple” depends on the performance that we want to boost and on the environment that we have to deal with.


2017 - A software-defined 5G cellular network with links virtually pooled for public safety operators [Articolo su rivista]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin
abstract

During disaster relief operations, public safety personnel performs data communication almost exclusively through terrestrial commercial networks. However, common cellular infrastructures are often unable to provide acceptable throughput and even basic availability owing to congestion or infrastructural disruption. In order to overcome these issues, this paper proposes the implementation of a network abstraction that we define as virtual resource pooling. This allows to virtually pool the resources provided by the cellular channels on which field operators are connected. The proposal aims to harmoniously blend together the multihoming capabilities of modern devices and their collaborative potential by leveraging the software-defined networking facilities that are expected to be present in the core infrastructures of fifth-generation networks. Coupled with the envisioned performance and packet core plasticity of the latter, such a system may have the potential to provide future public safety operators with broadband capabilities and high quality of experience in day-to-day tasks and major planned events while providing improved communication guarantees in unplanned disasters. To experimentally assess our proposal, we present a test bed that has been built and used to perform network emulation runs and to extract their results. These indicate that a system with virtual resource pooling may greatly enhance not only throughput and quality of service properties but also the resilience guarantees that network tenants may offer to field operators.


2017 - How to avoid TCP Congestion without dropping Packets: an Effective AQM called PINK [Articolo su rivista]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

This paper proposes PINK (Passive INverse feedbacK), a queue management algorithm designed to indi- rectly impose a certain resource allocation policy on defined sets of client hosts. PINK adds intelligence at intermediate nodes that connect client hosts to bottleneck links or to external networks in general, al- lowing these nodes to dynamically modify the TCP Acknowledgements (ACKs) segments passing through. The modification consists in replacing advertised Receive Window fields (RCV.WNDs) with custom values, in order to enforce a specific bandwidth utilization upper bound. To compute new RCV.WND values, PINK needs only the number of active connections, the flows RTTs and the transmission channel bandwidth. It follows that PINK permits to impose a centralized bandwidth management without the cooperation of clients, which means that no modification or addition to end hosts is needed. Furthermore, as demon- strated in this paper, our proposal does not constrain client hosts performance without purpose; on the contrary, PINK improves efficiency on multiplexed channels by exploiting their capacity and by main- taining a low queuing delay and guarantees optimal flow fairness without forcing any packet drop. We validate PINK performance in multiple scenarios by using the ns-3 network simulator.


2017 - Mitigating Congestion and Bufferbloat on Satellite Networks through a Rate-Based AQM [Relazione in Atti di Convegno]
Grazia, CARLO AUGUSTO; Patriciello, Natale; Klapez, Martin; Casoni, Maurizio
abstract

Satellite networking is known to suffer from specific network performance issues, such as high latency and low throughput stability; this derives mainly from the high propagation delay, in particular with GEO satellites. This characteristic poses limitations on the benefits that general AQM solutions could introduce; in fact, reducing congestion and mitigating queueing delay is a vital feature that could boost the performance of satellite networks. This paper investigates PINK (Passive INverse feedbacK), a queue management algorithm designed to indirectly impose an individual resource allocation policy in order to mitigate the bufferbloat effect and the network congestion while exploiting the channel throughput and guaranteeing optimal flow fairness without forcing any packet drop. PINK modifies the TCP Acknowledgements (ACKs) segments passing through the Satellite access gateway. The modification consists in replacing the advertised Receive Windows field (RCV.WNDs) with custom values, in order to enforce a particular bandwidth utilization upper bound. To compute new RCV.WND values, PINK needs only the number of active connections, the flows RTT and the transmission channel bandwidth. The design characteristics of this new AQM let it works efficiently in satellite networks, and we validate this statement through several simulations performed with the ns-3 network simulator.


2017 - Reducing Cellular Networks Power Consumption: the Role of Resource Pooling and Cooperation [Relazione in Atti di Convegno]
Klapez, Martin; Grazia, CARLO AUGUSTO; Casoni, Maurizio
abstract

This paper discusses the role that resource pooling and cooperation may play in reducing the ever-growing power consumption of cellular networks. These two abstractions are often referred to as methods to enhance communication throughput and increase data transmission resilience. The goal of this work is to advocate and highlight that they can also represent effective directions to go through in order to save significant amounts of energy and consequently reduce the greenhouse gas emissions generated by cellular communications. To demonstrate their potential, this paper presents a network abstraction called Virtual Resource Pooling, that has been designed to enable transparent, network-aware, and massively multipath transmissions through a harmonious integration between the multi-homing capabilities of modern devices and their collaborative potential. In addition to a notional presentation, the paper includes network emulation results that lay out the potential improvements of the proposal to network efficiency. These indicate that the system can scale transmission performance linearly with the number of concurrently forwarding nodes, effectively allowing to harness the unused network resources, and enabling to decouple the network’s energy consumption from the average QoE perceived by users.


2017 - SDN-Based Resource Pooling to Provide Transparent Multi-Path Communications [Articolo su rivista]
Casoni, M.; Grazia, C. A.; Klapez, M.
abstract

Fueled by the ever growing consumption of digital content and services, providers of packet- switched networks suffer more and more a conflict between network engineering constraints and end-user usage patterns. This conflict is due to the fact that deployed networks exhibit low efficiency in their average resource utilization rate, which stands opposed to, at times, unsatisfiable resource request peaks generated by users. Multipath transmissions are theoretically able to temper this offset, but have been an uphill road due to the complexity they require to dominate. This article proposes a network paradigm able to transparently provide end users with such capabilities, by virtually pooling network resources through Software-Defined Networking. It is shown how this discipline may be deployed in current network infrastructures, while complying with the main 5G architectures envisaged so far. It is advocated how such an effort may allow service providers to meet users’ expectations and strengthen profits without the need for unbearable financial investments, at the same time seamlessly improving their networks’ performance, reliability, resource utilization efficiency and energy consumption. To demonstrate the technical feasibility and the potential benefits of the proposed approach, we present a set of emulation results showing that the sweet spot between n-fold performance increases and robust resilience properties can be practically met.


2017 - TCP Performance Evaluation over Backpressure-based Routing Strategies for Wireless Mesh Backhaul in LTE Networks [Articolo su rivista]
Patriciello, Natale; Nunez Martınez, Josè; Baranda, Jorge; Casoni, Maurizio; Mangues Bafalluy, Josep
abstract

Wireless redundant networks are expected to play a fundamental role to backhaul dense LTE networks. In these scenarios, backpressure-based routing strategies such as BP-MR can exploit the network redun- dancy. In this paper, we perform an exhaustive performance evaluation of different TCP variants over an LTE access network, backhauled by various routing protocols (including per-packet and per-flow BP-MR variants and a static alternative, OLSR ) over two different wireless topologies: a regular mesh and an ir- regular ring-tree topology. We compare the performance of different TCP congestion control algorithms based on loss (NewReno, Cubic, Highspeed, Westwood, Hybla, and Scalable) and delay (Vegas) under dif- ferent workloads. Our extensive analysis with ns-3 on throughput, fairness, scalability and latency reveals that the underlying backhaul routing scheme seems irrelevant for delay-based TCPs, whereas per-flow variant offers the best performance irrespective of any loss-based TCP congestion control, the most used in the current Internet. We show that BP-MR per-flow highly reduces the download finish time, if com- pared with OLSR and BP-MR per-packet , despite showing higher round-trip-time.


2017 - Technology independent Scheduling Architecture for V2X Communications: a Flexible approach [Relazione in Atti di Convegno]
Grazia, CARLO AUGUSTO; Casoni, Maurizio
abstract

Vehicle-to-Everything (V2X) communications encapsulate significant challenges as a result of the vast number of wireless technologies deployed, nodes mobility and large applications range. One of the greatest challenges is to provide adequate QoS guarantees even in this demanding environment. State-ofthe-art solutions for QoS provisioning over wireless links are based on cross-layering packet schedulers that deal both with the QoS guarantees and the wireless link issues. Unfortunately, such an approach is not flexible and requires technology-dependent solutions, with the definition of a different software version for of the each technology deployed. To overcome this issue, we design a modular architecture which permits the use of existing high-performance packet schedulers for wired links over generic wireless technologies, as they are, and at the same time allows the flexibility to adapt to different channel conditions. We also provide a mathematical analysis of the QoS bounds of this novel architecture together with simulations analysis to validate it. This approach paves the way for efficient QoS provisioning and throughput-boosting in V2X systems.


2017 - Which AQM fits IoT better? [Relazione in Atti di Convegno]
Grazia, Carlo Augusto; Patriciello, Natale; Klapez, Martin; Casoni, Maurizio
abstract

Most of the Internet traffic is carried by Transmission Control Protocol (TCP) nowadays, even in the case of real-time services and IoT environments. A key point of each TCP variant that defines the specific variant trademark is the congestion control algorithm. This congestion control, alone, is not able to mitigate the congestion problem completely; the most efficient solution, to be coupled with it, is the Active Queue Manager (AQM). In this paper, we analyze the response to congestion provided by the novel AQMs when coupled with popular TCP variants and, has happened in IoT networks, with a mix of TCP variants simultaneously active on the network. We provide extensive simulations within ns-3 to highlight what is the better AQM solution for IoT networks by considering the TCP algorithm and other environmental conditions like the number of active nodes, the network RTT and the presence of multiple RTT flows. We collected network metrics like throughput, goodput, latency, RTT variation, flows’ fairness and a simple drop analysis.


2016 - A Congestion Control Middleware Layer with Dynamic Bandwidth Management for Satellite Communications [Articolo su rivista]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

Historically, satellites have been set aside for what regards Internet connectivity; however, the interest in their usage to provide Internet connectivity is now rising again. Because of the growing demand for Internet services around the world, satellites can be an effective medium to serve scarcely populated areas as well as missioncritical communications. While the standard transmission control protocol (TCP) performs badly when employed on satellite links for the high propagation delay, when a number of client hosts are wirelessly connected to a gateway that forwards and receives traffic across such links, the major limit is represented by the channel condition estimation performed by the TCP through loss detection and/or acknowledgement-based timing information. This paper proposes congestion control middleware layer (C2MLC), a centralized and collaborative middleware with dynamic bandwidth management, that aims to improve performance and QoS for TCP flows in the aforementioned scenarios. Results of ns-3 simulations show an improvement in aggregate throughput, a significant reduction of latencies because of low queues occupancy levels, and higher fairness and friendliness guarantees among flows. They also confirm that C2MLC allows a dynamic and efficient usage of the bottleneck link, avoiding a waste of resources when some client nodes are unable to fully exploit their transmission potential.


2016 - A Holistic Approach to Future Public Safety Communication Systems’ Evolution – Overview of FP7 EU PPDR-TC Project’s Outcomes [Relazione in Atti di Convegno]
Kanakidis, Dimitris; Sdongos, Evangelos; Lavaux, Damien; Jackson, James; McCrone, Natasha; Tsagkaropoulos, Michalis; Burns, John; Gierszal, Henryk; Tyczka, Piotr; Samp, Krzysztof; Antonio, Pedro; Casoni, Maurizio
abstract

The paper presents the main results and conclusions of the recently completed FP7 EU project entitled “Public Protection and Disaster Relief – Transformation Centre” – PPDR-TC. The major objective of PPDR-TC project was to provide the strategic roadmap towards the full migration path of future PPDR system’s evolution satisfying the mid and long-term requirements for the next 10-15 years. In order to cope with this goal PPDR-TC established a modular study approach with several building blocks. In addition, PPDR-TC project produced a series of techno-economical recommendations, supported by a comprehensive set of simulations and field trials to prepare a transition roadmap from current voice-centred PPDR networks to broadband-capable communication systems.


2016 - An SDN and CPS based opportunistic Upload Splitting for mobile users [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin
abstract

This paper proposes an hybrid approach composed by Software Defined Networking (SDN) and Cyber-Physical Systems (CPS) to boost the upload speed of mobile users in low-bandwidth environments through a next generation Mobile Collaborative Community (MCC). The core idea is to use a high-bandwidth local communication system, like IEEE 802.11 (WiFi), in order to distribute data efficiently through mobile hosts; then, the distributed data may be sent from each mobile node to the original destination through their low-bandwidth mobile interface for wide area network communication. With our solution some drawbacks of MCC are faced. With the use of SDN we defined a flexible and easy-to-configure MCC system which operates in a transparent way for the end hosts. At the same time, the use of CPS creates a feedback for the system regarding the hosts channel status; this way the system is able to fully exploit the MCC potential by increasing the upload speed for both congested and non-congested scenarios.We demonstrate the efficiency of our solution through experimental results obtained using the Mininet network emulator where POX and a Pyretic controller serve as a dynamic data repartition engine.


2016 - Enabling Resource Pooling in Wireless Networks through Software-Defined Orchestration [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Klapez, Martin
abstract

This paper proposes a network paradigm where network resources are virtually pooled through an OpenFlow controller that serves as the network orchestrator. The benefits that our proposal may guarantee with respect to the solutions currently published in literature are the installation, configuration and implementation simplicity, strong expandability properties, fallback behavior if needed, resilience to link failures, improvement of uplink data rates in addition to the downlink and, last but not least, the compatibility with common equipment, as no ad-hoc network protocols are needed. To assess the performance of our proposal, we present the test bed that has been built and used to extract the emulation results. Depending on the network characteristics, it is shown how an efficient orchestrator may succeed in allowing users to efficiently exploit the available network resources. We also show how, even in the worst-cases, the proposal exhibits significant performance improvements with respect to transfers where resources are not pooled among hosts.


2016 - Enabling Smart Environments by avoiding TCP Congestion through PINK: a no-drop AQM [Relazione in Atti di Convegno]
Grazia, Carlo Augusto; Patriciello, Natale; Klapez, Martin; Casoni, Maurizio
abstract

This paper proposes PINK (Passive INverse feed-bacK), a queue management algorithm designed to indirectly impose a certain resource allocation policy on defined sets of client hosts. PINK adds intelligence at intermediate nodes that connect client hosts to bottleneck links or to external networks in general, allowing these nodes to dynamically modify the TCP Acknowledgments (ACKs) segments passing through. This is made by setting TCP ACK advertised Receive Windows field (RCV.WNDs) to custom values, in order to enforce a specific bandwidth utilization upper bound. To compute new RCV.WND values, PINK needs only the number of active connections, the flows RTTs and the transmission channel bandwidth. It follows that PINK permits to impose a centralized bandwidth management without the cooperation of clients, which means that no modification or addition whatsoever to end hosts is needed with the goal of enabling a smart environment by simply configuring the access node. Furthermore, as demonstrated in this paper, our proposal does not constraints client hosts performance without purpose; on the contrary, PINK improves efficiency on multiplexed channels by exploiting channel throughput, main- taining a low queuing delay, and guaranteeing optimal flow fairness without forcing any packet drop.


2016 - Next-generation TCP for ns-3 simulator [Articolo su rivista]
Casoni, Maurizio; Patriciello, Natale
abstract

Ns-3 simulator provides a great platform for experimental studies on different communi- cation technologies and network topologies, and it is already used by many researchers all around the world. Unfortunately, its current TCP implementation is outdated and not ready for being used as reference platform for TCP-centered research, relegating ns-3 to play a background role in favor of its predecessor, ns-2. This paper presents the update process of ns-3 TCP module, that offers to TCP devel- opers and researchers a consistent and RFC-compliant platform to base their works on. The method involves the addition of a new congestion-based state machine, the split of congestion control out from the socket core, and the development of a very detailed and complete testing framework, which can be easily extended. Performance tests follow the description, comparing RAM usage and execution time between ns-3 releases. Also, a case study over high-delay links on the interaction between the Transmission Control Protocol (TCP) and CoDel, an Active Queue Management algo- rithm born to control queuing delay, is presented.


2016 - Performance Evaluation of Backpressure Routing in Integrated Satellite-terrestrial Backhaul for PPDR Networks [Relazione in Atti di Convegno]
Grazia, Carlo Augusto; Patriciello, Natale; Casoni, Maurizio; Núñez Martínez, Jose; Baranda, Jorge; Mangues Bafalluy, Josep
abstract

After a disaster, it is unlikely to expect current terrestrial infrastructures to provide the coverage and the Qualityof Service required by emergency operators. Currently, PPDR operators go towards a portable LTE infrastructure that provides an access network to field operators, backhauled by a wireless mesh network that can route traffic from and towards Internet through a satellite gateway. We firstly propose a new per-flow strategy for a backpressure-based routing protocol, BP-MR, and then in the aforementioned environment we analyse the original BP-MR per-packet, the proposed per-flow, and OLSR as routing protocol for the mesh network coupled with three TCP congestion control (Cubic, Hybla, Vegas) performing a typical HTTP transfer. We analysed the throughput, the latency, and the scalability over the number of the flows/operators. An extensive simulation set allows to conclude that employing BP-MR per-flow in the mesh network coupled with TCP Vegas for performing the end-to-end transfer improves the performance for PPDR professionals.


2016 - Towards Massively Multipath Transmissions for Public Safety Communications [Relazione in Atti di Convegno]
Grazia, Carlo Augusto; Klapez, Martin; Casoni, Maurizio
abstract

During their day-to-day tasks, public safety operators rely on commercial mobile networks in order to perform data communications and make use of data-based services. In major disasters, however, it is the norm to witness high degrees of network congestion and, often, to experience service outages caused by infrastructural damage. This may strongly hinder the operativity of emergency operators, that expect to rely on resilient communication infrastructures and that demand network availability no matter what. In order for today mobile networks to provide such capabilities, some degree of redundancy should be introduced, either in hardware as infrastructural deployments or in software as data replication mechanisms. This paper focuses on the latter approach. It proposes a network framework to enable collaborative hosts to concurrently forward replicated data over an arbitrary number of channels, in order to compensate for high packet losses or sudden unavailability of routing paths. The data replication and the forwarding behavior are concerted by an SDN controller, that transparently implements a network abstraction to virtually pool hosts network resources. The paper also presents the test bed that has been built and used to extract the emulation results. These demonstrate that the proposal have the potential to strongly improve data communication capabilities in constrained scenarios, in the form of higher data rates and stronger resilience guarantees. Last but not least, it is shown that services availability may be provided in much more cases, even when regular operativity fails.


2015 - A Cooperative Middleware for Enhancing TCP Performance over High Delay Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Klapez, Martin; Patriciello, Natale
abstract

When multiple nodes share the same gateway or access the same link, the throughput of wireless communications has the unfortunate problem of being limited by traffic congestion; the situation may also further degrade if they establish multiple TCP connections mapped over the same access channel. In end-to-end connections, TCP congestion control plays a critical role in order to not overflow the channel, although most of the network bandwidth bottlenecks are caused by the wireless systems. When TCP is coupled with high-delay channels, the protocol underperform; this is mainly due to long propagation delay, as it is the case with satellite links. To overcome the limitations of TCP on these links, various variants have been proposed, both rate-based or or burst-based. In this paper we present a cooperative transmission control that enhances the effectiveness of TCP asking only for a narrow senderside modification, operating exclusively at the access stage. It allows to boost throughput over high delay channels, increasing also fairness and friendliness between different TCP algorithms. After the description, we validate its effectiveness and show its properties by means of experimental results, derived from simulations performed on the ns-3 network simulator.


2015 - DyBRA: a Dynamic Bandwidth Reservation Algorithm to enhance Satellite Communications [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

In scenarios where a number of client nodes share a gateway in order to access a high-delay link, the original TCP as well as TCP variants specifically designed to improve performance on those links fail to provide optimal performance; this is due to the indirect inference of both end-to-end congestion and local channel conditions. To mitigate the former, C2ML (Congestion Control Middleware Layer) has been proposed as a tool for centralized and collaborative management of resources that can strongly improve performance for client hosts without affecting network resilience and connection survivability. To complete the picture, this paper proposes DyBRA, an improved version of C2ML with a bandwidth management algorithm designed to dynamically allocate bandwidth among client hosts on the basis of channel conditions, leading to improved performance regardless of the TCP variant employed by clients. Through simulations performed with the ns-3 network simulator, we show how DyBRA strongly improves throughput and TCP friendliness while reducing queue usage and latency.


2015 - Implementation and Validation of TCP Options and Congestion Control Algorithms for ns-3 [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

Currently, the ns-3 network simulator include rather limited TCP functionalities. TCP Options are not supported, and it misses models for widely used congestion control algorithms. Thus, simulations can be inadequate for today's standards and unable to represent what happen inside a broad range of networks, from Gigabit Ethernet to high-delay satellite channels. This paper presents an extension of the ns-3 TCP infrastructure, through the addition of the Window Scaling and the Timestamp Options as well as various models of TCP congestion control algorithms, from the widely used TCP Cubic to algorithms tailored for satellite or high Bandwidth-Delay Product links in general, namely TCP Hybla, Highspeed, Bic and Noordwijk. These additions are useful especially for research in high-speed or high-delay networks, filling the gap between real world and ns-3 TCP. Last but not least, this paper also presents some results regarding the validation of the added models, in order to demonstrate their correctness.


2015 - Integration of Satellite and LTE for Disaster Recovery [Articolo su rivista]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale; Amditis, Angelos; Sdongos, Evangelos
abstract

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.


2015 - Performance Evaluation and Economic Modelling of PPDR Communication Systems [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale; Gierszal, H.; Tyczka, P.; Pawlina, K.; Amditis, A.; Sdongos, E.
abstract

Network-enabled services for public protection and disaster relief (PPDR) professionals have been more than necessary in today’s emergency situations. Under the extreme circumstances of an emergency, it is essential to have networks which support the required data throughput as well as high availability in spite of high traffic volume, and which minimize the end-to-end delay for applications: however, the choice between the existing technologies is not so easy for PPDR entities, given the high number of parameters associated to satisfying the stringent PPDR requirements,high investments required to permit desirable availability as well as modernization of the existing services (i.e. voice and data) and design constraints posed by network providers as current deployed network reach their boundaries when emergencies occur. This paper analyzes three different emergency scenarios and then presents a subset of the results obtained in terms of financial and economic recommendations, along with technical reports on throughput and end-toend delay.


2015 - PINK: Proactive INjection into acK, a queue manager to impose fair resource allocation among TCP flows [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

This paper presents preliminary work on PINK (Proactive INjection into acK), an AQM algorithm able to enhance TCP congestion control properties without dropping packets. PINK is a completely transparent solution that does not require any modification to the existing protocol stack of end hosts, and it is particularly suitable for high-delay PPDR systems. The algorithm is based on an explicit feedback scheme, able to enforce a fair bandwidth sharing among clients by modifying the Receive Window in TCP acknowledgements returning to them; such a feedback is computed for each flow, and it only needs the number of active connections, the flows RTTs and the shared link bandwidth. Therefore, PINK is a per-flow stateless AQM that works independently from the TCP algorithm used by clients, and it is fair regardless the flows RTTs, which is a key feature for PPDR systems. The effectiveness of the proposed algorithm is demonstrated using the ns-3 simulator.


2015 - QRM: A queue rate management for fairness and TCP flooding protection in mission-critical networks [Articolo su rivista]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

When statistical multiplexing is used to provide connectivity to a number of client hosts through a high-delay link, the original TCP as well as TCP variants designed to improve performance on those links often provide poor performance and sub-optimal QoS properties. Centralised and collaborative resource management tools like C2ML have been proposed to guarantee intra-protocol fairness, inter-protocol friendliness, low queues utilisation and optimal throughput along with the reliable delivery of packets. However, such tools offer only very limited security guarantees. Both good citizenship and security from flooding attacks are fundamental conditions for the provision of fairness, especially in mission-critical networks. For example, perpetrators of a man-provoked disaster may want to perform a resource exhaustion attack on the network supporting disaster recovery operations, so as to cut out legitimate users from the communications and increase the emergency impact. In this paper we present Queue Rate Management (QRM), an Active Queue Management scheme able to provide protection from traffic overflow attacks in scenarios where access to the shared link is controlled by a tool that assigns to client hosts a bandwidth upper bound. The proposed algorithm checks whether a node is exceeding its allowed rate, and consequently decides whether to keep or drop packets coming from that host. We mathematically prove that with QRM the gateway queue size can never exceed the Bandwidth-Delay Product of the channel. Furthermore, we employ the ns-3 network simulator to compare QRM with CoDel, RED and GREEN, showing how QRM provides better performance in terms of both throughput and QoS guarantees in the aforementioned scenarios.


2015 - Towards Emergency Networks Security with Per-Flow Queue Rate Management [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, Carlo Augusto; Klapez, Martin; Patriciello, Natale
abstract

When statistical multiplexing is used to provide connectivity to a number of client hosts through a high-delay link, the original TCP as well as TCP variants born to improve performance on those links often provide poor performance and sub-optimal QoS properties. To guarantee intra-protocol fairness, inter-protocol friendliness, low queues utilization and optimal throughput in mission-critical scenarios, Congestion Control Middleware Layer (C2ML) has been proposed as a tool for centralized and collaborative resource management. However, C2ML offers only very limited security guarantees. Because emergencies may be natural or man-provoked, in the latter case there may be interest to cut out legitimate users from the communication networks that support disaster recovery operations. In this paper we present Queue Rate Management (QRM), an Active Queue Management scheme able to provide protection from Resource Exhaustion Attacks in scenarios where access to the shared link is controlled by C2ML; the proposed algorithm checks whether a node is exceeding its allowed rate, and consequently decides whether to keep or drop packets coming from that node. We mathematically prove that with QRM the gateway queue size can never exceed the Bandwidth-Delay Product of the channel. Furthermore, we use the ns-3 simulator to compare QRM with CoDel and RED, showing how QRM provides better performance in terms of both throughput and QoS guarantees when employed with C2ML.


2014 - A Low-Latency and High-Throughput Scheduler for Emergency and Wireless Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Valente, Paolo
abstract

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 Highthroughput Twin Fair scheduler (HFS), outperforms one of the most accurate and efficient integrated schedulers available in the literature.


2014 - Energy Efficiency of an Integrated Intra-Data-Center and Core Network With Edge Caching [Articolo su rivista]
M., Fiorani; S., Aleksic; P., Monti; J., Chen; Casoni, Maurizio; L., Wosinska
abstract

The expected growth of traffic demand may lead to a dramatic increase in the network energy consumption, which needs to be handled in order to guarantee scalability and sustainability of the infrastructure. There are many efforts to improve energy efficiency in communication networks, ranging from the component technology to the architectural and service-level approaches. Because data centers and content delivery networks are responsible for the majority of the energy consumption in the information and communication technology sector, in this paper we address network energy efficiency at the architectural and service levels and propose a unified network architecture that provides both intra-data-center and inter-data-center connectivity together with interconnection toward legacy IP networks. The architecture is well suited for the carrier cloud model, where both data-center and telecom infrastructure are owned and operated by the same entity. It is based on the hybrid optical switching (HOS) concept for achieving high network performance and energy efficiency. Therefore, we refer to it as an integrated HOS network. The main advantage of the integration of core and intra-data-center networks comes from the possibility to avoid the energy-inefficient electronic interfaces between data centers and telecom networks. Our results have verified that the integrated HOS network introduces a higher number of benefits in terms of energy efficiency and network delays compared to the conventional nonintegrated solution. At the service level, recent studies demonstrated that the use of distributed video cache servers can be beneficial in reducing energy consumption of intra-data-center and core networks. However, these studies only take into consideration conventional network solutions based on IP electronic switching, which are characterized by relatively high energy consumption. When a more energy-efficient switching technology, such as HOS, is employed, the advantage of using distributed video cache servers becomes less obvious. In this paper we evaluate the impact of video servers employed at the edge nodes of the integrated HOS network to understand whether edge caching could have any benefit for carrier cloud operators utilizing a HOS network architecture. We have demonstrated that if the distributed video cache servers are not properly dimensioned they may have a negative impact on the benefit obtained by the integrated HOS network.


2014 - Energy-Efficient Elastic Optical Interconnect Architecture for Data Centers [Articolo su rivista]
M., Fiorani; S., Aleksic; Casoni, Maurizio; L., Wosinska; J., Chen
abstract

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.


2014 - E-SPONDER System: A new Communication Infrastructure for Future Emergency Networks [Relazione in Atti di Convegno]
T., Campana; Casoni, Maurizio; A., Karagiannis; K., Maliatsos; A., Marousis
abstract

This paper describes a novel emergency communication network architecture implemented within the FP7 EU project E-SPONDER. It is characterized by the deployment of heterogeneous wireless systems and also by its holistic approach achieving reliability, high performance, reconfigurability and standalone operation. It is a complete suite of real-time communication technologies built to support the first responders with information services during disaster events. This work investigates the system architecture in an aircraft landing incident and describes a field test carried on at Schiphol airport in Amsterdam. More specifically, a scalable and adaptive telecommunication architecture that ensures voice, video and data between first responders and command centers at all times, even under extreme conditions, is presented. The structure and functionalities of the VoIP subsystem that operates above the proposed heterogeneous E-SPONDER network architecture is described, with a detailed scenario analysis. Finally, the paper presents how the recommended solutions are integrated into an implementable platform.


2014 - Green Backhauling for Rural Areas [Relazione in Atti di Convegno]
M., Fiorani; S., Tombaz; P., Monti; Casoni, Maurizio; L., Wosinska
abstract

Providing wireless broadband access to rural and remote areas is becoming a big challenge for wireless operators, mostly because of the need for a cost-effective and low energyconsuming mobile backhaul. However, to the best of our knowledge, energy consumption of different options for backhauling of future rural wireless broadband networks has not been studied yet. Therefore, in this paper we assess the energy consumption of future rural wireless broadband network deployments and backhaul technologies. In the wireless segment, two deployment strategies are considered, one with macro base station only, and one with small base stations. In the backhaul segment, two wireless, i.e., microwave and satellite, and one optical fiber based (i.e., long reach passive optical networks) solutions are considered. These options are compared in terms of their ability to satisfy coverage, capacity and QoS requirements of a number of rural users in the time span that goes from 2010 until 2021. From the presented results it is possible to conclude that wireless backhaul solutions can significantly increase the energy consumption of the access network. In contrast, the long reach PON based backhaul has much higher energy efficiency and in the long term might be a better choice for wireless operators.


2014 - Hybrid Optical Switching for Data Center Networks [Articolo su rivista]
M., Fiorani; S., Aleksic; Casoni, Maurizio
abstract

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 transportmechanism 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.


2014 - Integration between Terrestrial and Satellite Networks: the PPDR-TC vision [Relazione in Atti di Convegno]
Grazia, CARLO AUGUSTO; M., Klapez; N., Patriciello; Casoni, Maurizio; A., Amditis; E., Sdongos; H., Gierszal; D., Kanakidis; C., Katsigiannis; K., Romanowski; P., Simplicio; A., Oliveira; S., Sonander; J., Jackson
abstract

Wireless communication technologies are critical for public protection and disaster relief (PPDR) professionals during the emergency operations that follow natural or man-made disasters, scenarios in which commercial terrestrial networks often fail to provide the necessary support. The reason is threefold: they simply get disrupted 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. In every PPDR operation reliable voice communications are critical, especially in the very early stages of the response; nevertheless, there is an increasing demand from the PPDR community for a wider range of data-centric services. While current technologies used for PPDR operations provide a rich set of voice-centric services, they are unable to sustain high-bandwidth data-oriented applications. As the PPDR-TC EU consortium, we propose a hybrid approach to tackle the question of determining the future architecture for Pan-European PPDR networks based on the integration of Terrestrial and Satellite technologies, presenting our first simulation results on the integration of LTE and Satellite Networks.


2014 - Reducing Latency in Satellite Emergency Networks through a Cooperative Transmission Control [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Klapez, Martin; Patriciello, Natale
abstract

The vast majority of efforts aimed to improve network performance are focused on the increase of application throughput. The same holds in the context of Emergency Networks, where operators ask for more bandwidth in order to exploit data-intensive services. Following a steady growth in network capacities and number of users, large buffers have been inserted all over the Internet. Their effects on networks are non-trivial: while they may effectively serve the purpose of exploiting the channel potential, they also create unnecessary delays by damaging the behavior of the most common transport protocol, TCP. Nevertheless, they are being assumed by new congestion control algorithms, especially those tailored for high-latency links such as satellite ones. According to the anywhere-anytime paradigm, these channels represents a key technology for both Emergency and General-Purpose networks. In this paper we first show how buffer lengths impact the perceived delay over satellite links that employ a recently proposed burst-based TCP protocol, and then present a cooperative transmission control that reduce buffers usage and latency while keeping high throughput and flow fairness, thus allowing for a better service provision through satellite links.


2014 - TCP Performance in Multi-EPON Access Networks under Different Optical Core Switching Paradigms [Articolo su rivista]
Casoni, Maurizio; W., Cerroni; M., Fiorani
abstract

In this paper the end-to-end TCP performance of a hybrid network composed of multiple Ethernet Passive Optical Networks (EPONs) in the access segment connected to the same edge node of a core network is evaluated. Three possible core network paradigms are considered: Optical Circuit Switching (OCS), Optical Burst Switching (OBS) and Optical Packet Switching (OPS). TCP performance is evaluated through simulations with ns-2. The hybrid network scalability is assessed by varying the number of EPONs connected to the same edge node and the number of Optical Network Units (ONUs) per EPON. Interoperability issues between access and core are investigated and the impact of the most important network parameters is highlighted. The three transfer modes considered for the core network are properly compared under different input conditions, discussing the related trade-offs that may lead to the most suitable choice based on the specific application scenario. Finally, some design issues are investigated with reference to emerging Long-Range EPON (LR-EPON) solutions.


2014 - TEMPEST: a new Test EnvironMent for Performance Evaluation of the Scheduling of packeTs [Articolo su rivista]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Valente, Paolo
abstract

The packet scheduling problem has been deeply studied for lot of years by researchers in the computer science and telecommunications fields as an important solution that decides the order in which packets are sent over a link in order to provide QoS on a network. Recently, the packet scheduling has become again a challenging topic due to the massive use of wireless technologies (e.g. WiFi, LTE, 4G/5G) with which to provide high QoS guarantees is still an open problem. Unfortunately, it is difficult to compare different solutions and actually test them in order to select the most proper packet scheduler for each particular environment. In this paper we present TEMPEST, a new Test EnvironMent for Performance Evaluation of the Scheduling of packeTs, which is a novel tool able to help the research in the packet scheduling field. TEMPEST is able to measure the actual performance of a packet scheduler in several environments, both wired or wireless, like the execution time, QoS metrics and throughput, giving prompt feedback about the quality of the solution studied. The goal of this paper is to present in detail the current features of TEMPEST, showing how it is easy to add, configure, test and evaluate several scheduling solutions in multiple scenarios.


2014 - TEMPEST: Test EnvironMent for Performance Evaluation of the Scheduling of packeTs [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Valente, Paolo
abstract

The packet scheduling problem has been deeply studied for lot of years by researchers in the computer science and telecommunications fields as an important solution that decides the order in which packets are sent over a link in order to provide QoS on a network. Recently, the packet scheduling has become again a challenging topic due to the massive use of wireless technologies (e.g. WiFi, LTE, 4G/5G), both for public and PPDR networks, with which to provide high QoS guarantees is still an open problem. Unfortunately, it is difficult to compare different solutions and actually test them in order to select the most proper packet scheduler for each particular environment. In this paper we present TEMPEST, a new Test EnvironMent for Performance Evaluation of the Scheduling of packeTs, which is a novel tool able to help the research in the packet scheduling field. TEMPEST is able to measure the actual performance of a packet scheduler in several environments, both wired or wireless, like the execution time, QoS metrics and throughput, giving prompt feedback about the quality of the solution studied. The goal of this paper is to present in detail the current features of TEMPEST, showing how it is easy to add, configure, test and evaluate several scheduling solutions in multiple scenarios.


2013 - A Flexible and Green Scheduler for providing QoS and High Throughput over Wireless Links [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Valente, Paolo
abstract

Realizing a communication system over wireless links that simultaneously offers QoS guarantees, high throughput and low energy consumption is a difficult task. 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 little flexible and does not allow any of the existing high-quality schedulers for wired links to be used without modification. To address these issues, in this paper we validate a modular architecture which permits the use, as they are, of existing packet schedulers for wired links over wireless links, and at the same time allows the flexibility to adapt to different channel conditions. We validate the effectiveness of the modular architecture by showing, through experimental results, that this architecture enables us to get a new scheduler with the following features, just by combining existing schedulers: execution time and energy consumption close to that of just a Deficit Round Robin, accurate fairness and delay guarantees, possibility to set, by changing one parameter, the desired trade-off between throughput-boosting level and granularity of the service guarantees. In particular, we show that this scheduler, which we named High-throughput Twin Fair scheduler (HFS), outperforms one of the most accurate and efficient integrated schedulers available in the literature.


2013 - A Green, Modular and Fair Packet Scheduler for Boosting Throughput over Wireless Links [Articolo su rivista]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; Valente, Paolo
abstract

We study the problem of defining and implementing a packet scheduler able to give the high performance of a wired packet scheduler over a wireless link, i.e. a low execution time with low power consumption, high QoS guarantees and high throughput. 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 little flexible and does not allow any of the existing high-quality schedulers for wired links to be used without modification. To address these issues, in this paper we validate a modular architecture which permits the use, as they are, of existing packet schedulers for wired links over wireless links, and at the same time allows the flexibility to adapt to different channel conditions. We validate the effectiveness of the modular architecture by showing, through experimental results, that this architecture enables us to get a new scheduler with the following features, just by combining existing schedulers: execution time and energy consumption close to that of just a Deficit Round Robin, accurate fairness and delay guarantees, possibility to set, by changing one parameter, the desired trade-off between throughput-boosting level and granularity of the service guarantees. In particular, we show that this scheduler, which we named High-throughput Twin Fair scheduler (HFS), outperforms one of the most accurate and efficient integrated schedulers available in the literature.


2013 - A Modular Architecture for QoS Provisioning over Wireless Links [Relazione in Atti di Convegno]
Casoni, Maurizio; Paganelli, Alessandro; Valente, Paolo
abstract

We consider the problem of providing QoS guarantees, and at the same time boosting the throughput or saving energy over a wireless link. 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 does not allow any of the existing high-quality schedulers for wired links to be used without modification. And it is little flexible, as a scheduler compliant with a given wireless technology may need to be modified to fit a different technology or a different solution for saving energy. To address these issues, in this paper we propose a modular architecture that basically extends the network stack by adding a special middle layer on top of the MAC. On the bottom side, this middle layer deals with the idiosyncrasies of the underlying wireless link, and possibly uses channel state information to boost performance and save energy. On the top side, the middle layer exports the abstraction of a link to which the higher layers must only pass the packets to transmit. On top of this middle layer, existing packet schedulers for wired links can be used without modification. It is then possible also to use the same packet scheduler on heterogeneous wireless technologies, by changing only the the middle layer.


2013 - A tool for multimedia quality assessment in NS3: QoE Monitor [Articolo su rivista]
D., Saladino; A., Paganelli; Casoni, Maurizio
abstract

Nowadays, with the continuous rise of Internet-based multimedia services, such as video sharing websites, web radios and IP-based telephony, multimedia communications are gaining more and more popularity. From the service provider’s perspective, there is an increasing need in providing highquality content; at the same time, from the network provider’s view, the requirement is to design networks that can effectively support these services with adequate quality-ofservice (QoS). In both cases, engineers and researchers need suitable planning tools exploitable for providing appropriate designs. For all these reasons, we have focused our work on the design and implementation of a novel open-source tool, named QoE Monitor, which consists of a new module for the NS-3 simulator that can be used to perform objective and full-reference quality-of-experience (QoE) assessments in any simulated network. The goal of this tool is to predict the video and/or audio quality perceived by an end user through objective metrics. Moreover, its open-source nature foster its validation and promote knowledge sharing within the research community, while its modularity eases the implementation of additional software components to expand its capabilities (e.g., to account for new codecs and/or new QoE metrics). In this paper, a detailed description of this tool is done and some numerical results about video streaming performance evaluations are presented, which show its effectiveness for the QoE analysis.


2013 - Adaptive Hybrid Optical Switching: Performance and Energy efficiency [Articolo su rivista]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

Hybrid optical switching (HOS) has the potential to provide highly efficient operation through combining various switching paradigms and different implementation options within the same network. The flexibility of choosing between circuit, packet or burst switching and electronic or optical implementation results in an improvement of both energy and data transport efficiency because the most appropriate method and less power consuming elements can be selected and used for transmission of data through the network while temporarily inactive elements are switched off or put in a low-power mode. In this paper, we introduce a novel network concept that we refer to as adaptive hybrid optical switching (AHOS) and present and investigate several architectures and realization options for AHOS nodes. The corresponding control plane comprises two layers, of which one implements routing, signalling and link management functions as defined in the GMPLS standard while the other is responsible for managing already established circuits and scheduling the transmission of packets and bursts. We present results on both performance and energy consumption for different AHOS node realizations, network configurations and traffic patterns, which prove the potential for a high improvement in energy efficiency with respect to conventional electronic packetswitched networks.


2013 - An Ad-hoc Emergency Network for Crisis Events [Relazione in Atti di Convegno]
Casoni, Maurizio; D., Saladino; A., Karagiannis; D., Komnakos; S. E., Sagkriotis; J., Wagner; N., Joram; F., Ellinger
abstract

This paper describes the work that is currently performed in the European FP7 project “A Holistic Approach Toward the Development of the First Responder of the Future”, that is funded by the European Commission under its Security Program. This work aims at providing an overview of a novel emergency network architecture. It represents a complete suite of real-time communication technologies exploitable to support the first responders with information services during disaster events. More specifically, this work will investigate the system architecture, in terms of network structure, the provided communication services, the available technologies and how the recommended solutions will be really implemented.


2013 - Hybrid Optical Switching for an Energy-Efficient Internet Core [Articolo su rivista]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

As Internet traffic grows, current core network technologies will raise issues in terms of energy consumption. Here, the authors propose three possible optical network architectures for the next-generation Internet core, including an all-optical hybrid optical switching (HOS) network, an optical/electronic HOS network, and an all-electronic switching network. They evaluate and compare all three networks with regard to performance and power consumption via an event-driven simulator.


2013 - Hybrid Optical Switching for Energy-Efficiency and QoS Differentiation in Core Networks [Articolo su rivista]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

In the future, the Internet may ultimately be constrained by energy consumption and the capability to provide quality of service (QoS). As regards the Internet core, hybrid optical switching (HOS) is promising to provide service differentiation and reduced energy consumption in respect to current electronic switching solutions. In this paper we present a novel hybrid HOS network architecture that efficiently integrates the optical packet, burst, and circuit switching on the same network. The proposed HOS network envisages the use of two parallel switches, a slow optical switch for the transmission of circuits and long bursts, and a fast switch for the transmission of packets and short bursts. The most appropriate switching method is selected for the traffic generated by different applications and the less power consuming elements are utilized for transmission, ensuring flexibility, QoS differentiation, and low energy consumption. The HOS network is organized in an overlay model with the HOS control layer performing routing, signaling, and link management, and with the HOS forwarding layer managing the reservation of resources and data scheduling. Performance and energy efficiency of the analyzed network are assessed by means of a combined analytical and simulation approach.


2013 - Large Data Center Interconnects Employing Hybrid Optical Switching [Relazione in Atti di Convegno]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

Current data centers (DCs) networks rely on electronic switching and point-to-point interconnects. When considering future DC requirements, point-to-point interconnects will lead to poor network scalability and large power consumption. For this reason several optical switched interconnects for DCs have been recently proposed. However, the proposed optical switching solutions suffer from low flexibility and are not able to provide service differentiation. Furthermore, very few studies evaluate possible improvements in energy efficiency offered by optical switching solutions. In this paper we introduce a novel architecture of interconnects for DCs based on hybrid optical switching (HOS). HOS combines three different optical switching paradigms, namely circuit, burst and packet switching within the same network. Furthermore, HOS envisages the use a two parallel optical switches, a slow and low power consuming switch for the transmission of data using circuits and long bursts, and a fast switch for the transmission of packets and short bursts. The possibility of choosing between circuits, bursts and packets ensures the flexibility required by future DCs. At the same time, the option to select the most suitable switch technology for each data flow guarantees high transmission efficiency and low power consumption.


2013 - On the Effectiveness of Linux Containers for Network Virtualization [Articolo su rivista]
G., Calarco; Casoni, Maurizio
abstract

This paper presents a novel approach to the study of multi-technological networks based on Linux containers and software emulators. We illustrate the architecture and implementation issues of a modular and flexible testbed (NetBoxIT) that supports the virtualization and the concurrent, real-time execution of several independent emulators on a single, multi-core hardware platform. Distinct virtual networks can be instantiated, and connected to synthesize heterogeneous networks configurations. NetBoxIT is also an open platform, which can be interfaced with external networks and nodes, enabling the evaluation of true users’ applications and protocols. We examine its performance under different viewpoints (scalability, computational load, timing overheads, and realism) and we show how the proposed testbed architecture leads to a general-purpose, reliable, and economical tool for assessing multipart networks with respect to real-world applications. Moreover, we discuss which are the current and future technologies that can be introduced to reduce the testbed timing overheads and to further improve performance.


2013 - On the Performance of Linux Container with Netmap/VALE for Networks Virtualization [Relazione in Atti di Convegno]
Casoni, Maurizio; Grazia, CARLO AUGUSTO; N., Patriciello
abstract

In this paper we study the problem of how to simulate complex networks on general-purpose hardware in an efficient, feasible and scalable way. State of the art solutions for network simulation are based on the virtualization of network simulators (so as to emulate network’s nodes) or on the usage of specialized software that models the network itself (so as to emulate network’s links). The former solution suffers in terms of computational overhead and global network’s throughput, while the latter can’t be employed in actual real-world scenarios. We focus on the interconnection technologies between network nodes, implemented as Linux Containers, by evaluating a recent framework for packet exchange, Netmap, coupled with a Virtual Local Ethernet used as a generic high speed bus, VALE. We then compared our work with existing and standard Linux solutions, namely Virtual Ethernet interfaces and Virtual Bridges, finding out that our approach allows efficient simulation of complex networks by means of virtualization techniques, nevertheless achieving both high throughput and low overhead when exchanging packets among nodes.


2012 - Analysis of a GMPLS Enabled Hybrid Optical Switching Network [Relazione in Atti di Convegno]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

In this paper a novel control plane for hybrid opticalswitching (HOS) networks is proposed. The control plane employsgeneralized multiprotocol label switching (GMPLS) for configuringthe virtual topology, and for establishing and tearing downthe label switched paths. The management of the different trafficgranularities, including resource reservation and data scheduling,is yielded by the HOS control layer. Furthermore, the architectureof a node that can be managed by the proposed control plane isintroduced, and a model for its power consumption evaluation ispresented. The power consumption of the considered architectureis then compared with the power consumption of a current IPelectronic router. Performance and power consumption of theproposed HOS network are evaluated through the use of anevent-driven simulator.


2012 - Energy Efficiency of Hybrid Optical Switching [Relazione in Atti di Convegno]
S., Aleksic; M., Fiorani; Casoni, Maurizio
abstract

Hybrid optical switching (HOS) has the potential to provide highly efficient operation through combiningvarious switching paradigms and different implementation options within the same network. The flexibility ofchoosing between circuit, packet or burst switching and electronic or optical implementation results in animprovement in both energy and data transport efficiency because the most appropriate method and less powerconsuming elements can be selected and used for transmission of data through the network while inactiveelements are switched off or put in a low-power mode. In this paper, we propose a novel network concept thatwe refer to as adaptive hybrid optical switching (AHOS) and present and investigate several architectures andrealization options for AHOS nodes. The corresponding control plane comprises two layers, of which oneimplements routing, signalling and link management functions as defined in the GMPLS standard while theother one is responsible for managing already established circuits and scheduling the transmission of packetsand bursts. We present results on both performance and energy consumption for different AHOS noderealizations, network configurations and traffic patterns, which prove the potential for a high improvement inenergy efficiency from 100% to approximately 1,000% with respect to the conventional electronic packetrouters.


2012 - NetBoxIT: an Open Testbed for Heterogeneous Networks Study [Relazione in Atti di Convegno]
G., Calarco; Casoni, Maurizio
abstract

This paper presents a novel approach to the study of heterogeneous networks. NetBoxIT is a modular, and scalable testbed based on virtualized network emulators. These can be interconnected and run in parallel to reproduce complex networks scenarios within a shared, multi-core hardware platform. We examine the testbed performance with simple emulation trials (related to the reference Emergency Network under study within the EU 7th FP project “A holistic approach towards the development of the first responder of the future”), to verify its realism in assessing multipart networks evaluations.


2012 - QoS Performance Evaluation of Multimedia Services in Emergency Networks [Relazione in Atti di Convegno]
A., Paganelli; D., Saladino; Casoni, Maurizio
abstract

This work describes the main communication services that have to be provided by any emergency network, together with their bandwidth and network requirements. One of them is voice over IP (VoIP), which is fundamental to coordinate all the necessary rescue operations during a disaster event.However, this service alone is not sufficient for the current needs of any modern (or future) public safety system. Indeed, it has to be accompanied by other important services, like video over IP (VIP) to film the incident area, the transmission of sensor data (e.g., temperature, heartbeat, etc.), and generic file transfer service. In order to design a modern and efficient emergency communication network able to support all of these applications,the first step will be the analysis of the theoretical bandwidth requirements of each network segment. Besides, we will show numerical results, obtained by means of computer simulations,in order to demonstrate that the considered services can be supported, in a reference network architecture, guaranteeing a satisfactory QoS.


2011 - End-to-End Performance of Heterogeneous Multi-EPON/OBS Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; W., Cerroni
abstract

In this paper end-to-end performance is evaluated when multiple high-speed access networks, based on the Ethernet Passive Optical Network (EPON) technology, are interconnected through an Optical Burst Switching (OBS) core network. The inter-working unit, or edge node, between these two different networks is properly studied and discussed. A time-based burst assembly algorithm is assumed, which is analyzed and dimensionedto cope with multiple EPONs. The role of a key parameter,such as the EPON cycle time used in the multiple access scheme,is assessed. Transport layer performance of the multi-EPON/OBSnetwork is evaluated through simulations with ns2. Results showthat the relationship between the EPON cycle time and the burstassembly time has a fundamental role and requires proper tuningto optimize, e.g., the TCP throughput.


2011 - NetBoxIT: Virtual Emulation Integrated Testbed for the heterogeneous Networks Design [Relazione in Atti di Convegno]
G., Calarco; Casoni, Maurizio
abstract

We present a novel approach to heterogeneousnetworks study based on the implementation of a modular,extensible, and scalable testbed that uses virtualized networkemulators. Our goal is to reproduce complex networks scenariosby interconnecting several emulators, concurrently runningwithin a single hardware platform. This paper analyzes thetestbed performance with simple emulation trials, to verify if it issuitable for assessing multipart networks evaluations.


2011 - Performance and Power Consumption Analysis of a Hybrid Optical Core Node [Articolo su rivista]
M., Fiorani; Casoni, Maurizio; S., Aleksic
abstract

Hybrid optical switching (HOS) is a switchingparadigm that aims to combine optical circuit switching,optical burst switching, and optical packet switching on thesame network. This paper proposes a novel integrated controlplane for an HOS core node. The control plane makes use ofa unified control packet able to carry the control informationfor all the different data formats and employs an appropriatescheduling algorithm for each incoming data type. Threepossible node architectures are presented and an analyticalmodel is introduced to analyze their power consumption. Also,the concept of increase in power efficiency is introduced tocompare the considered architectures. The performance andpower consumption analysis of the node have been carried outthrough the use of a simulation model developed specificallyfor the scope. The obtained results show the effectiveness ofHOS networks.


2011 - Security Issues in Emergency Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; A., Paganelli
abstract

This paper reviews the most important securityproperties found in computer systems in the context of thenetwork infrastructure for public safety emergency responsesystems. The goal of this research has been to find what propertiesmost affect the design of an emergency response network,together with the study of the set of the available solutions thatcan be used to implement these properties in an actual emergencynetwork.


2011 - Transport Layer Performance of Hybrid Networks Combining Multiple EPONs and OBS [Relazione in Atti di Convegno]
Casoni, Maurizio; W., Cerroni; M., Fiorani
abstract

In this paper the performance of a hybrid opticalnetwork composed of multiple Ethernet Passive Optical Networks(EPONs) at the access connected to an Optical Burst Switching(OBS) core is evaluated. The EPONs make use of the IPACTalgorithm to manage the upstream transmissions, whereas theOBS edge node employs a time-based assembly scheme forburst aggregation. This leads to interoperability issues betweenaccess and core which are investigated in this paper. Thehybrid network scalability is proved by assessing the transportlayer performance with different numbers of EPONs served bythe same burst assembler and different numbers of OpticalNetwork Units (ONUs) per EPON. The impact of the maindesign parameters affecting the interaction between EPONs andOBS is estimated. The transport layer performance is evaluatedconsidering heterogeneous traffic flows by simulating both TCPand UDP sources.


2011 - Virtual Networks and Software Router approach for Wireless Emergency Networks Design [Relazione in Atti di Convegno]
G., Calarco; Casoni, Maurizio
abstract

This paper presents some of the activities currentlyperformed within the European Union 7th FrameworkProgramme project “A holistic approach towards thedevelopment of the first responder of the future”. It is a suite ofreal-time data-centric technologies that will provide enhancedinformation and communication support to first responders thatact during normal and abnormal events. The paper demonstratesthe way virtual networks and software routers tools can beappropriate to design and evaluate the telecommunicationinfrastructure.


2010 - A Satellite based System for Managing Crisis Scenarios: the E-SPONDER Perspective [Relazione in Atti di Convegno]
G., Calarco; Casoni, Maurizio; A., Paganelli; D., Vassiliadis; M., Wodczak
abstract

This paper presents the work that is currently performedin the E-SPONDER (FP7-242411) project. E-SPONDERis a project co-funded by the European Commission under itsSecurity Program.E-SPONDER is a suite of real-time data-centric technologiesthat will provide information and communication support tofirst responders which act during normal and abnormal events(crises). It will investigate the use of interoperable communicationsthat will facilitate the uninterruptible link between the firstresponders at the operations theatre and the crisis managersat the Emergency Operations Center. To achieve that, a novelarchitecture is introduced that brings satellite communicationsin the spotlight of effective first response work.The paper demonstrates the way satellite communications willbe integrated to the E-SPONDER system in order to ensurealways-on communications and data exchange.


2010 - TCP Window Estimation for Burst Assembly in OBS Networks [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

In this paper TCP performance over Optical Burst Switching networks is investigated by considering the burst assembly function implemented in the edge nodes.This function has a very important role on end-to-end performance and a edge node architecture is here proposed for improving performance.A multi-queue burst assembly algorithm which is based on an estimation of the current TCP window is proposed and evaluated.Results show that this algorithm can lead to TCP performance improvements of 100 %, compared to timer-based assembly operating on a single queue.The OBS network is evaluated through simulations by means of the ns2 simulation tool.


2010 - Wireless Networks at the Service of effective First Response Work: the E-SPONDER Vision [Relazione in Atti di Convegno]
Casoni, Maurizio; G., Calarco; A., Paganelli; D., Vassiliadis; Garbi, A. n.; R., Morera; C. M., Chen; M., Wodzcak
abstract

This paper presents the work that is cur rentlyperformed in the E-SPONDER (FP7-242411) project. ESPONDERis a suite of real-time data-centric technologies whichwill provide actionable information and communication supportto first responders that act during normal and abnormal events(crises). This information will enable improved control andmanagement, resulting in real time synchronization betweenforces on the ground (police, rescue, firefighters) and out-oftheatercommand and control centers (C&C). The approachguiding the E-SPONDER project is based on the fusion ofvariable forms of field-derived data within a central systemwhich will then provide information analysis and decisionsupport applications at designated C &C locations in order toprovide in situ support to first responders that operate in CriticalInfrastructures.


2009 - Hands-On Networking From Theory to Practice [Monografia/Trattato scientifico]
Merani, Maria Luisa; Casoni, Maurizio; Cerroni, Walter
abstract

Learn the core theory and explore real-world networking issues with this richly illustrated example-based textbook. It provides an accurate view of modern networks through detailed coverage of the most relevant networking technologies, with no unnecessary extras. Carefully designed, affordable laboratory exercises based on open-source software networking tools are included for hands-on practice with real networking devices. Numerous case studies and examples further link theory to practice, whilst the topologies, tools and configurations needed to carry out practical exercises are provided to guide students through each task. Its bottom-up approach is easy for students to follow and perfect for lab-oriented courses.


2009 - System Design and Evaluation of a Large Photonic Switch based onOptical Codes for Optical Burst Switched Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; A., Sacchi
abstract

This paper investigates the performance of a multi-stage Clos architecture having a bufferless switch based on optical codes as basic switching element. This multi-stage switch is suitable as core node in OBS networks. Optical codes are used for coding incoming bursts in each switching element to perform the switching function. To this end it employs encoders and decoders and possible output contentions are solved in the wavelength domain by means of variable-input fixed-output wavelength converters. A core node with this multi-stage architecture is compared with a monolithic single-stage switch, with the goal to evaluate the performance feasibility of a large Terabit optical switch.In order to study the performance of this switch architecture, we have useda simulation tool, that we have developed and we call M_OBS_SIM(Modular OBS Simulator). The main figure of merit here investigated is the burstblocking probability as a function of different load conditions and switch size.The main result is that a 3-stage Clos architecture can be used for the realization of a Terabit OBS core switch based on optical codes.


2009 - TCP Performance in Hybrid EPON/OBS Networks [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

paper no. 1569165364


2009 - TCP Performance in Hybrid Multigranular OBS Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; C., Raffaelli
abstract

This paper studies TCP performance with different offset times which arise when hybrid multi-granular technology is employed in OBS core nodes. Multi-granular switches are promising devices to match dynamic application needs while optimizing switch costs and feasibility. They foster optical burst switching in multi-service contexts where switching matrices are designed and optimized in application awareness. OBS base offset time is strictly dependent on switching matrix set up time which, in presence of hybrid technology, is different from path to path. These differences impact on end-to-end performance and in particular on TCP throughput. This work studies end-to-end performance for two basic classes of connections, namely slow and fast connections. Simulations results based on a careful set up of ns-2 simulations according to test bed configurations described in literature are provided to show the effects of the employment of different optical technologies on the TCP throughput.


2009 - TCP Performance over Optical Burst-Switched Networks with Different Access Technologies [Articolo su rivista]
Casoni, Maurizio; C., Raffaelli
abstract

Different access networks are here considered when interconnected with an optical wide area network based on the optical burst switching transfer mode. End-to-end performance is evaluated when the TCP protocol is employed. The effects on TCP of access network protocols and of the burst assembly procedure performed at the ingress edge nodes are evaluated both in wired and wireless scenarios, with optical and electrical technologies. The influence of the assembly time out in the different access contexts is presented and numerical investigations are performed by means of ns-2 simulations.Results show that end-to-end throughput is mostly influenced by the delay introduced by access protocols, which arises in the different scenarios, and by the assembly time out. These results provide meaningful insights for the overall system design and, in particular, for the setting of the inter-working unit parameters.


2008 - A Novel Photonic Switch Architecture based on Optical Codes for Optical Burst Switched Networks [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

This paper proposes a novel bufferless switch architecture based on optical codes, suitable as core node in OBS (optical burst switched) networks. Optical codes are used for coding incoming bursts in order to perform the switching function. To this end the proposed switch architecture employs encoders and decoders and possible output contentions are solved in the wavelength domain by means of variable-input fixed-output wavelength converters. A core node with this architecture is compared with another bufferless core node architecture which employs a limited set of shared variable-input variable-output wavelength converters.In order to study the performance of the novel switch architecture, we have useda modular and flexible simulation tool, that we have developed and we call M\_OBS\_SIM(Modular OBS Simulator). The main figure of merit here investigated is the burstblocking probability as a function of different load conditions.The main result is that the novel switch architecture has shown the same performance in all scenarios as the node based on variable-input variable-output converters but at lower costs, since it does not make use of this kind of expensive converters.


2008 - A Simulation Study of the IPACT protocol for Ethernet Passive Optical Networks [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

In this paper a particular Passive Optical Network based on the Ethernet framing is investigated considering a typical tree-based topology. User stations are managed for upstream data transmissions by means of a polling algorithm which has also to support a dynamic bandwidth management. Here the Interleaved Polling with Adaptive Cycle Time (IPACT) algorithm is investigated and evaluated through simulation, exploitiong the ns simulation tool. Different scheduling disciplines which the IPACT may employ are evaluated in terms od bandwidth distribution, cycle times and queue lenghts.


2008 - Effectiveness and issues of congestion control in 802.11g wireless LANs [Articolo su rivista]
Borri, M; Casoni, Maurizio; Merani, Maria Luisa
abstract

The current paper presents a collection of experimentaldata portraying the performance achieved in the wirelesssetting by several TCP-friendly congestion controls recentlyproposed in literature. Thiswork is partly motivated bythe consideration that the majority of the analytical results inthis area are validated by simulation, rather than by field tests.Examining these algorithms in real environments can helpverify their actual effectiveness over the wireless Internet.To reach such goal, two representative controls among theso-called window-based TCP-friendly schemes have beenimplemented, namely, the General Additive Increase MultiplicativeDecrease (GAIMD) strategy, and the SQuare RooT(SQRT) binomial control; the most representative algorithmamong rate-based controls, the TCP Friendly Rate Control(TFRC), has also been considered. Their TCP-fairnessand smoothness have been comprehensively evaluated in anIEEE 802.11g Wireless Local Area Network (WLAN). Theobtained results show that the GAIMD and SQRT strategiesreveal non-negligible scalability and smoothness problems,that markedly limit their performance. It is empiricallydemonstrated that their “optimal” increase/decrease rules,based on TCP-Reno analytical model, cannot guarantee anadequate performance when GAIMD and SQRT competewith TCP-Sack, a de facto standard for current TCP implementations.TFRC is demonstrated to occasionally behave bewildering: properly tuning one of its congestion controlparameters and enhancing the algorithm with a flow-controlmechanism result in a definitely fairer share of bandwidthwith concurrent TCP flows.


2008 - TCP Performance For Users On Trains in Presence Of Hand-Overs Due To Tunnels [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

In this paper the reference system is given by wireless usersaboard of fast moving vehicles, such as trains, connected to theInternet by means of satellite links. Performance of several TCPflavors are investigated in this scenario and they are obtained bysimulation in presence of hand-overs which happen when a trainenters a tunnel and the satellite comes to be unreachable. Thesehand-overs imply time intervals during which data flows are slowdown or blocked. Results show that depending on their duration,users performance can be remarkably affected.


2007 - Analytical Framework for End-to-End Design of Optical Burst-Switched Networks [Articolo su rivista]
Casoni, Maurizio; Raffaelli, C.
abstract

This paper presents an analytical model of TCP throughput in optical burst-switched (OBS) networks. Several parameterscharacterize this system and influence the network design process, such as the assembly time, the access bandwidth, the burstloss rate, and they are taken into account in the formulation of TCP send rates. Moreover burst loss is considered a consequenceof contention in core nodes and it is formulated in relation to a quite general core node architecture. The novelty of the workis represented by the possibility of analytically representing the whole end-to-end connection so that a fast and effective tool toevaluate the relationships between network and access design is provided. An application example is given to prove the practicalsignificance of the approach. Simulation results are provided to validate the model and the related assumptions.


2007 - Multiple TCP Flow Performance Study over Optical Burst Switched Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; A. M., Guidotti; C., Raffaelli
abstract

This paper investigates the TCP performance over optical burst switched networks. Optical burst assembly is a key function for the internetworking between TCP/IP networks and optical burst switched networks and it significantly influences the TCP behaviour. The burst assembly/disassembly process takes place at network edges and two main assembly strategies are here investigated, per flow and mixed flow. In this paper TCP performance are studied focusing on the multiple flow scenario and the main results obtained by simulation are reported and discussed.


2007 - Research in Optical Burst Switching within the e-Photon/ONe Network of Excellence [Articolo su rivista]
Casoni, Maurizio
abstract

This paper presents a summary of Optical Burst Switching (OBS) research within the VI framework program e-Photon/ONenetwork of excellence. The paper includes network aspects such as routing techniques, resilience and contention resolution, togetherwith burst switch architectures. On the other hand, we also discuss traffic analysis issues, Quality of Service (QoS) schemes, TCP/IPover OBS and physical layer aspects for OBS.


2006 - Lezioni di TECNICHE DI INTERCONNESSIONE [Monografia/Trattato scientifico]
Casoni, Maurizio
abstract

Questo libro illustra le tematiche di maggiore interesse nel campo delle reti di telecomunicazioni, riassumendone brevemente gli aspetti di base. Si pone quindi come naturale evoluzione dei corsi di base volendo fornire al lettore una visione delle reti odierne sia a circuito sia a pacchetto, sia di accesso sia di dorsale ed un utile supporto al loro studio.Sono presentati inoltre alcuni strumenti utili per la valutazione delle prestazioni delle reti.


2006 - M_OBS_SIM: A powerful modular optical burst switched (OBS) network SIMulator [Articolo su rivista]
Casoni, Maurizio; Luppi, E; Manzoli, U; Merani, Maria Luisa
abstract

This paper introduces M_OBS_SIM, a network simulator conceived to evaluate the performance of networks where the Optical Burst Switching (OBS) paradigm is implemented. Its accurate design allows to investigate the behavior of optical edge and core routers, as well as to assess the performance of the whole optical network; its modular construction guarantees a high degree of flexibility and a facilitated introduction of further developments. Its functional blocks, properly configured, allow to explore the effects that the most salient features of an OBS network - input traffic statistics, assembly algorithms, resource reservation policies, routing strategies - have on user performance. New and valuable results for different classes of applications with diverse service requirements are provided and discussed. (C) 2006 Elsevier B.V. All rights reserved.


2006 - Performance Evaluation of Channel Scheduling Algorithms With Different QoS Classes [Relazione in Atti di Convegno]
Casoni, Maurizio; Luppi, E; Merani, Maria Luisa
abstract

This paper compares the performance of different schedulingalgorithms, with and without void filling, considering a completeOptical Burst Switched (OBS) network scenario, given by edge andcore routers, under real traffic conditions.Performance is investigated taking into account both burst lossprobability and the complexity of the algorithms, evaluated interms of scheduling time. For an effective comparison both aspectshave to be considered in order to understand if an algorithm whichprovides low burst blocking probabilities is actually feasible ornot.In this paper the authors propose a scheduling algorithm whichrepresents a good trade-off between burst blocking performance andscheduling time.


2006 - TCP Performance for Vehicular Users Through Satellite Links [Relazione in Atti di Convegno]
Casoni, Maurizio; Luppi, E.
abstract

In this paper the reference system is given by wireless usersaboard of fast moving vehicles, such as trains, connected to theInternet by means of satellite links. Performance of several TCPflavors are investigated in this scenario using a PerformanceEnhancing Proxy architecture. TCP performance are reported also in presence of UDP flows and some enhancements, such as large initial window and window scale, and are evaluated in terms of throughput and fairness. Results show that TCP Vegas is the best performing when large initial window and window scale options areimplemented.


2006 - The research agenda in optical burst switching in e-photon/ONe [Relazione in Atti di Convegno]
Aracil, J.; Bjornstad, S.; Casoni, M.; Christodoulopoulos, K.; Fdez-Palacios, J.; Gauger, C.; Gonzalez, O.; Hu, G.; Karasan, E.; Klinkowski, M.; Morato, D.; Nejabati, R.; Overby, H.; Raffaelli, C.; Simeonidou, D.; Sole-Pareta, J.; Stol, N.; Tosi Beleffi, G. M.; Vlachos, K.
abstract

This talk provides an overview of the current research in Optical Burst Switching within the EU network of excellence e-Photon/ONe, comprising network aspects such as routing techniques, resilience and contention resolution, together with burst switch architectures. On the other hand, we also discuss traffic analysis issues, Quality of Service (QoS) schemes, TCP/IP over OBS and physical layer aspects for OBS.


2005 - An Experimental Study on Congestion Control in Wireless and Wired Networks [Relazione in Atti di Convegno]
M., Borri; Casoni, Maurizio; Merani, Maria Luisa
abstract

This paper presents an extensive experimental analysis of two TCP-friendly congestion controls recently proposed in the literature, placing a special emphasis on the wireless setting. This work is motivated in part by the consideration that, to our knowledge, the majority of the results in this area are validated by simulation analysis rather than by experimentation. Testing these algorithms in real environments can help to verify their actual effectiveness for possible employment over the Internet. To reach our goal, we have implemented one representative algorithm among the so-called window-based TCP-friendly congestion controls, namely, the general additive increase multiplicative decrease (GAIMD) strategy, and used the publicly available code for the most popular control of the rate-based family, i.e., the TCP-friendly rate control (TFRC). We have then evaluated their TCP-fairness and smoothness in a test-bed featuring Cisco WAN equipment, as well as in an IEEE 802.11g wireless local area network (WLAN). Based on our results, we first propose and justify the tuning of TFRC to avoid a weird behavior that in the wireless environment this control occasionally exhibited. We next show that the GAIMD strategy reveals non-negligible scalability and smoothness problems that limit its performance, mainly in the radio setting. We empirically demonstrate that its increase/decrease rules, based on a TCP-Reno analytical model, do not guarantee an adequate performance when GAIMD competes with TCP-Sack, a de facto standard for current TCP implementations.


2005 - On the performance of TCP over optical burst switched networks with different QoS classes [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

In this paper we investigate the end-to-end performance of an optical burst switched (OBS) network that adopts a core router architecture with no fiber delay lines and limited set of wavelength converters. In particular, by evaluating both the node and a reference network performance in terms of burst blocking probability we want to determine the end-to-end performance when a transport protocol like TCP is employed. Core node analysis is employed to identify the blocking experienced by incoming bursts, under the assumption of exponentially distributed burst interarrival times and arbitrarily distributed burst durations.


2004 - Congestion Control in Wireless Environments: Experimental Assessments and Simulation [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

This work investigates the TCP-friendliness of a particular congestion control mechanism, the TCP friendly rate control protocol (TFRC), when it is employed to regulate the transmission rate of nonTCP sources competing for bandwidth with different TCP flows (Reno, Sack and Westwood) in an IEEE 802.11b wireless LAN. Throughput of simultaneously active TFRC and TCP flows have been both experimentally measured and investigated through simulation, revealing that the wireless indoor radio channel plays a significant role on such parameter. Moreover, some useful insights have been derived on the behavior of TFRC and its degree of friendliness in an environment featuring a low degree of statistical multiplexing, such as the wireless context examined.


2004 - Impact of assembly algorithms on end-to-end performance in Optical Burst Switched networks with different QoS classes [Relazione in Atti di Convegno]
Casoni, M.; Luppi, E.; Merani, M. L.
abstract

This paper investigates the performance of a complete OBS (Optical Burst Switched) network that implements the JET (Just Enough Time) reservation mechanism. The network under examination adopts a core node architecture with no fiber delay lines and a limited set of wavelength converters, while featuring an edge node architecture with a mix of input, output and shared buffers. We investigate the overall network performance and design, specifically focusing on burst delay and end-to-end TCP throughput. In order to study the OBS network behavior, we develop a modular and flexible simulation tool, that we call MOBSSIM (Modular OBS Simulator). MOBSSIM is the means to accurately build an arbitrary topology OBS network via its main functional blocks, edge and core routers: its sound degree of development enables us to accurately evaluate several figures of merit, e.g., burst blocking probability and delay, and also allows for a critical comparison of alternative design solutions in terms of assembly algorithms, reservation strategies and QoS oriented routing.


2004 - Performance and TCP-fairness of TFRC in an 802.11g WLAN: Experiments and tuning [Relazione in Atti di Convegno]
M., Borri; Casoni, Maurizio; Merani, Maria Luisa
abstract

In this paper we discuss some experimental results obtained from a laboratory testing of TCP-friendly rate control (TFRC), when such control is employed in an IEEE 802.11g wireless local area network (WLAN). We show that, despite TFRC exhibiting a good responsive behavior and a considerable TCP-friendliness in a wired environment, occasionally it does not behave in the same manner in the wireless test-bed. We discuss the possible reasons of such unexpected behavior, and propose a tuning of some of its congestion indicators, as well as a simple enhancement of the control, in order to get rid of the undesirable effects we observed. In detail, our proposal consists of an additional mechanism for flow control, similar to the one TCP employs, of a more tightly computed no feedback timer, and of a parameter that rules the way TFRC backs-off when it detects a loss event. We pleasantly notice that our modifications and tuning result quite effective for two reasons: first, they completely succeed at eliminating the aggressive behavior sometimes exhibited by TFRC; second, they do not affect the good performance, nor the TCP-friendly behavior of TFRC in those circumstances where the native control already performs satisfyingly.


2003 - On the performance of TCP over a TDD-TD/CDMA architecture [Articolo su rivista]
Casoni, Maurizio
abstract

This paper determines the performance of TCP when it is employed over a TDD-TD/CDMA architecture which supports different classes of subscribers and adopts an interference-driven admission control policy. The blocking and the outage probability of the system users are evaluated under various traffic conditions as well as the TCP throughput that data users experience. Call blocking and TCP throughput are determined by means of a semi-analytical approach. This work shows that when TCP is taken into account, many options come out for the system design in order to optimize radio resources. Resource assignment in the TDD-TD/CDMA system can then be done as a function of the actual radio link quality with the goal both to serve as many users as possible and to keep the TCP throughput as high as possible. Copyright


2003 - Service Differentiation in Optical Burst Switching: Performance Evaluation under LRD Traffic [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

This work proposes a method for service differentiation in optical burst switching (OBS) nodes adopting theJust Enough Time, JET, reservation mechanism. It consists of optimizing the number of wavelength convertersemployed in the node and proper setting of the extra-offset time intervals to satisfy different levels of qualityof service (QoS). The ON/OFF model with exponentially distributed OFF periods, both exponentially andheavy-tailed distributed ON periods is adopted to assess the node performance under different traffic patterns.The OBS node investigated in this paper is equipped with M £M optical interfaces with N wavelengths eachat 2:5 Gbits/s. We suppose that wavelength converters are available and that the system is bufferless, i.e., nofiber delay lines are available. One way to reduce the blocking of higher priority users is to grant them a longerextra-offset time. Another way to provide higher priority users with better performance is to allow them onlyto employ wavelength converters. Low priority incoming bursts can be retransmitted on the output link on thesame wavelength only.


2003 - TCP/IP Performance over Optical Networks [Capitolo/Saggio]
F., Callegati; Casoni, Maurizio; C., Raffaelli
abstract

Capitolo 8TCP/IP Performance over Optical Networks


2002 - Admission control in T/CDMA systems supporting voice and data applications [Articolo su rivista]
Casoni, Maurizio; Immovilli, Gianni; Merani, Maria Luisa
abstract

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.


2002 - MPlS vs LOBS in an Optical Burst Switching Node: Impact ofLong-Range Dependent Traffic on Multiclass Services [Relazione in Atti di Convegno]
A., Brandani; Casoni, Maurizio; Merani, Maria Luisa
abstract

This work investigates the behavior of a reservation mechanismknown as JET, Just Enough Time, highly promisingin WDM networks adopting the optical burst switching(OBS) paradigm. In this article we assess the performance,in terms of burst blocking probability, that an optical crossconnectachieves when employing JET in conjunction withthe MultiProtocol Lambda Switching in the control planeon top of the optical layer, and compare it with the LabeledOptical Burst Switching, LOBS, solution. The burstblocking probabilities of three service classes with differentQoS requirements are determined, demonstrating thatthe LOBS alternative guarantees a remarkable improvementwith respect to the MultiProtocol Lambda Switching- OBS combination.


2002 - On the Performance of TCP over a TDD-T/CDMA Architecture [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

This paper determines the performance ofTCP when it is employed over a TDD-TD/CDMA architecturewhich supports different classes of subscribersand adopts an interference-driven admission control policy.The call blocking of the system users is evaluated aswell as the TCP throughput that data users experience.This work further shows that when TCP is taken intoaccount, many options come out for the system designin order to optimize radio resources. Furthermore, weshow that the TDD system can satisfyingly cope with remarkabletraffic loads but a careful tuning of the wirelesssystem is necessary.


2002 - Performance of TCP over Differentiated Services Networks withATM Switching Systems [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

This paper determines the performance ofTCP when it is employed over Differentiated ServicesNetwork where ATM switches are used as Label SwitchingRouters, as in Request for Comments 3035.A packet discard scheme is also evaluated with the goalto classify incoming data flows in different levels of qualityof service. In particular, the assured forwarding in theDifferentiated Services per-hop-behavior, as reported inthe Request for Comments 2597, is considered as referencescenario.Different degrees of quality of service imply differentportions of bandwidth and levels of packet loss for dataflows which share the same output link. TCP performanceis investigated for Low Drop Precedence flows, orhigh priority flows, when the considered packet discardscheme is employed during congestion intervals. Numericalresults are reported and discussed for different levelsof congestion.


2002 - Supporting Multirate Services in a TDD-TD/CDMA Architecture [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

In this study we determine the Erlang capacityof a TDD-TD/CDMA architecture providing multirateservices to different classes of subscribers. The qualityof service perceived by speech and data users is assessedand some design criteria are evidenced, with referenceto both traffic and transmission parameters.


2001 - DCA Schemes For Differentiated Qos In Microcells [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

This paper investigates in a microcellularset-up the behavior of a new class of dynamic channelallocation policies, tailored to provide different QoS degreesto distinct user classes of a wireless system. Theperformance achieved by a network employing theseschemes is evaluated in terms of call blocking, taking intoaccount the requirements raised by multi-rate applications.Some design criteria effective to optimize the managementof the scarce radio resources are furnished andthe goal of providing radio users with both low and highspeed connections, suitable for a basic set of audio andvideo applications, is achieved.


2001 - Erlang Capacity of a TDD-TD/CDMA Architecture Supporting Heterogeneous Traffic [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

In this paper we study the performance ofa TDD-TD/CDMA architecture with two classes of subscribers,voice and data, when an interference-driven admissioncontrol policy is adopted. The blocking and theoutage probability of the system users are evaluated undervarious traffic conditions for several uplink/downlinkconfigurations of the time slots, demonstrating that thetime division full duplex approach needs a careful tuningin order to maximize system capacity.


2001 - Erlang capacity of a TDD-TD/CDMA architecture supporting heterogeneous traffic [Articolo su rivista]
Casoni, Maurizio; Merani, Maria Luisa
abstract

This letter determines the capacity of a TDD-TD/CDMA architecture which supports different classes of subscribers and adopts an interference-driven admission control policy. The blocking probability of the system users are evaluated under various traffic conditions for several uplink/downlink configurations of the time slots, demonstrating that the time division full duplex approach needs a careful tuning in order to maximize system capacity.


2001 - Integrating voice and data applications in T/CDMA architectures [Articolo su rivista]
Casoni, Maurizio; Immovilli, Gianni; Merani, Maria Luisa
abstract

This letter analyzes the behavior of two time-code division architectures serving voice and data applications on the uplink of a cellular system. Both solutions attribute speech users one code over a timeslot, whereas data users are granted several codes over the same timeslot or a single code over several time slots. Call admission control dynamically attributes resources if specified levels of transmission quality are met. The blocking probability of the two classes of users is determined, demonstrating that the multicode T/CDMA approach performs better than the multislot solution and than a pure CDMA system.


2001 - On the Performance of TDD-TD/CDMA Architectures with Heterogeneous Traffic [Relazione in Atti di Convegno]
Casoni, Maurizio; Merani, Maria Luisa
abstract

This paper determines the capacity of a TDD- TD/CDMA architecture which supportsdifferent classes of subscribers and adopts an interference-drivenadmission control policy.The blocking and the outage probability of the system users areevaluated under various traffic conditionsfor several uplink/downlink configurations of the timeslots, demonstrating that the time division full duplex approach needs a careful tuningin order to maximize system capacity.Our work further shows that even when data traffic plays the predominant role,the TDD system can satisfyingly cope with remarkable traffic loads and support severalErlangs of traffic per cell.


2001 - Packet Discard Schemes for Differentiated Services Networks with ATM Switching Systems [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

In this paper two packet discard schemes are proposed with the goal to provide incoming data flows different levels of quality of service. In particular, the assured forwarding in the Differentiated Services per-hop-behavior, as reported in the Request For Comments 2597, is considered as reference scenario. The different levels of quality of service imply different portions of bandwidth assigned to data flows which share that same output link. Good performance in terms of throughput and fairness in bandwidth sharing among equal priority flows are also considered as the requirements to meet. The proposed schemes are also evaluated when end-to-end transport protocols, such as TCP, are employed so as to give some informations about their impact on applications. These dropping schemes are shown to provide good results and to represent a relatively low complex solution for dealing with the most demanding data flows during congestion intervals. Numerical results are reported and discussed for homogeneous and non homogeneous data sources.


2001 - Performance evaluation of an interference based admission control scheme in T/CDMA systems with voice and data users [Relazione in Atti di Convegno]
Casoni, M.; Immovilli, G.; Merani, M. L.
abstract

This paper analyzes the behavior of two time-code division architectures serving voice and data applications on the uplink of a cellular system. Both solutions attribute speech users one code over a time slot, whereas data users are granted several codes over the same time slot or a single code over several time slots. Call admission control is performed by a channel assignment algorithm which dynamically attributes resources if specified levels of transmission quality are met. The blocking probability of the two classes of users is determined, and it is demonstrated that the multicode T/CDMA approach performs better than the multislot solution and than a pure CDMA system.


2001 - Performance Evaluation of an Interference based admission control schemein T/CDMA systems with voice and dat users [Relazione in Atti di Convegno]
Casoni, Maurizio; Immovilli, Gianni; Merani, Maria Luisa
abstract

This paper analizes the behaviour of two-time code division architectures serving voice and data users on the uplink of a cellular system.


2000 - Channel Allocation Schemes Providing QoS in Wireless Networks [Relazione in Atti di Convegno]
Casoni, Maurizio; Immovilli, Gianni; Merani, Maria Luisa
abstract

In this paper we propose a new class of interference adaptive dynamic channel allocation policies, tailored to provide different QoS degrees in a cellular mobile radio system. The performance achieved by a wireless network employing these schemes is evaluated in terms of call blocking probability, in a multirate application scenario featuring heterogeneous traffic. Some useful design criteria to optimize the management of the scarse radio resources are also furnished: the ultimate goal is to provide radio users with high speed connections, suitable for a basic set of audio and video applications.


1999 - A Selective Packet Discard Scheme for Supporting Internet QoS in Congested ATM Switches [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

Previous papers have described and evaluated the performance ofpacket discard techniques for maintaining packet integrity during overloadin ATM switches but without taking into account different classes of service.In this paper a packet discard scheme is proposed with the goal toprovide incoming flows of cells with output link bandwidth dependingon the class of service they belong to. Also good performance in termsof throughput and fairness in bandwidth sharing among equal priorityflows are considered as the requirements to meet.In the scenarios here considered, the proposed discard scheme is shownto provide very good results and to represent a possible solution fordealing with the most demanding data flows during congestion intervals.Numerical results are reported and discussed for differentoperating conditions and traffic patterns.


1999 - Analysis of a Threshold Dropping Scheme for Different Service Classes in the Internet [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

n this paper a packet discard scheme is proposed with the goal toprovide incoming data flows with output link bandwidth dependingon the class of service they belong to. Good performance in termsof throughput and fairness in bandwidth sharing among equal priorityflows are also considered as the requirements to meet.The dropping scheme is shownto provide very good results and to represent a possible solution fordealing with the most demanding data flows during congestion intervals.Numerical results are reported and discussed for homogeneous and nonhomogeneous data sources.


1999 - Packet Optical Networks for High Speed TCP-IP Backbones [Articolo su rivista]
Bostica, B.; Callegati, F.; Casoni, Maurizio; Raffaelli, C.
abstract

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


1999 - Performance Analysis of Channel Allocation Schemes for Wireless Communications [Relazione in Atti di Convegno]
Casoni, Maurizio; M., Garuti; Immovilli, Gianni; Merani, Maria Luisa
abstract

This paper evaluates the performance of different networkinfrastructures for the support of multimedia services in a cellularmobile radio system. The performance of twodifferent channel allocation policies in terms of call blocking,outage probability and throughput are investigated for differentclasses of service that system users may require.A specific type of interference adaptive dynamic channel allocationscheme is here proposed and evaluated as possible solution foroptimizing the management of the scarce radio resources. The goal isto provide users with high speed connections, suitable for a basic setof audio and video applications.


1999 - Performance of A TCP-IP Backbone Based On Optical Packet Switching [Articolo su rivista]
Callegati, F.; Casoni, Maurizio; Raffaelli, C.; Bostica, B.; MASIP TORNÉ, J.; Burzio, M.; SOLÉ PARETA, J.
abstract

This paper presents a new proposal for TCP-IP backbone implementation based on optical packet switching.


1999 - Tandem Architecture for Photonic Packet Switches [Articolo su rivista]
Casoni, Maurizio; Raffaelli, C.
abstract

A new switch architecture is presented to enhance outputqueuing in photonic packet switches. Its application is for apacket switching environment based on the optical transport offixed length packets. This architecture consists of a couple of cascadingswitching elements with output queuing, whose buffer capacityis limited by photonic technology. The introduction of asuitable buffer management allows a very good and balanced exploitationof the available optical memories, realized with fiber delaylines. In particular, packet loss performance is here evaluatedshowing the improvement with respect to the single switch anda way to design large optical switches is shown in order to meetbroadband network requirements.


1998 - A Wireless ATM LAN with an 802.11-like Data Link Layer [Relazione in Atti di Convegno]
F., Callegati; Casoni, Maurizio; Merani, Maria Luisa; C., Raffaelli
abstract

In this paper a semi-analytical procedure isemployed to evaluate the performance of a wireless ATMlocal area network based on the IEEE 802.11 MAC protocol,taking into account the effects of propagation over a real radiochannel. Numerical results are presented as a function of theMAC frame length and of the signal-to-noise ratio in order toevaluate network performance and to provide guidelines forthe overall system design.


1998 - Architecture and Performance of a Broadcast and Select Photonic Switch [Articolo su rivista]
F., Callegati; Casoni, Maurizio; G., Corazza; C., Raffaelli; D., Chiaroni; F., Masetti; M., Sotom
abstract

A new photonic packet switch based on wavelength encoding ofinformation and on the broadcast-and-select principle for routing ispresented. A suitable management of a set of fiber delay lines toallow all-optical output queuing is performed through electroniccontrol. Implementation and traffic aspects are analyzed.Experimental results are given to demonstrate the feasibility of theswitch and its future evolution, achieved by a rack mountedsub-equipped demonstrator. Different design options are discussed inorder to achieve a global terabit per second capacity.Performance have been evaluated by simulation under the typicaltraffic conditions that arise in the broadband communicationenvironment.


1998 - Fair Packet Discard as Improvement of Early Packet Discard [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

Previous papers have described and evaluated theperformance of the Early Packet Discard techniquefor maintaining packet integrity during overload inATM switches.In this paper a packet discard scheme is proposedwith the goal to provide both good performance interms of throughput and fairness in terms of band-width exploitation of the output link among all vir-tual circuits. In the scenarios here considered, theproposed discard scheme is shown to provide verygood results and to represent therefore a remarkableimprovement of the classical Early Packet Discard.Numerical results are reported and discussed forcomparing these two discarding schemes under dif-ferent operating conditions.


1998 - Transparent Optical Packet Switching: the European ACTS KEOPS project approach [Articolo su rivista]
Casoni, Maurizio; Ii,
abstract

This paper reviews the work carried out under theEuropean ACTS KEOPS (KEys to Optical Packet Switching)project, centering on the definition, development and assessmentof optical packet switching and routing networks capable ofproviding transparency to the payload bit rate. The adoptedapproach uses optical packets of fixed duration with low bit rateheaders to facilitate processing at the network/node interfaces.The paper concentrates on the networking concepts developedin the KEOPS project through a description of the implementationissues pertinent to optical packet switching nodes andnetwork/node interfacing blocks, and consideration of the networkfunctionalities provided within the optical packet layer. Theimplementation, from necessity, relies on advanced optoelectroniccomponents specifically developed within the project, which arealso briefly described.


1997 - Early Packet Discard with Diverse Management Policies for EOM cells [Relazione in Atti di Convegno]
Casoni, Maurizio
abstract

Previous papers have described theEarly Packet Discard tecnique for maintaining packet integrity during overloadin ATM switches and evaluated the performance without properlydiscussing the role of End-of-Message cells in transmittedpackets. In this paper the performance, in terms of fraction ofthe link's capacity used to carry complete packets, are evaluated consideringdifferent ways to manage last cells ofAAL5 packets. This will be shown to be important for the end receiverand to require one extra control bit both to be able to cope withthe problem of merged packets and to have good performance.


1997 - Improved Analysis of Early Packet Discard [Relazione in Atti di Convegno]
Casoni, Maurizio; J. S., Turner
abstract

In a previous paper, one of the authors, gave a worst-case analysisfor the Early Packet Discard technique for maintaining packet integrityduring overload in ATM switches. This analysis showed that to ensure100% goodput during overload under worst-case conditions, requires a bufferwith enough storage for one maximum length packet from every active virtualcircuit. This paper refines that analysis, using assumptions that arecloser to what we expect to see in practice. Our principal result is that100% goodput can be achieved with substantially smaller buffers,although the required buffer space can be significant when the link speed issubstantially higher than the rate of the individual virtual circuits.These results are validated by comparison with simulation. We also givea simple analysis to determine the amount of buffering needed to boundthe probability of buffer overflow and underflow.


1997 - On the Performance of Early Packet Discard [Articolo su rivista]
Casoni, Maurizio; J. S., Turner
abstract

In a previous paper, one of the authors gave a worstcase analysis for the early packet discard (EPD) technique formaintaining packet integrity during overload in ATM switches.This analysis showed that to ensure 100% goodput during overloadunder worst case conditions requires a buffer with enoughstorage for one maximum length packet from every active virtualcircuit. This paper refines that analysis, using assumptions thatare closer to what we expect to see in practice, and examineshow EPD performs when the buffer is not large enough to achieve100% goodput.We show that 100% goodput can be achieved withsubstantially smaller buffers than predicted by the worst caseanalysis, although the required buffer space can be significantwhen the link speed is substantially higher than the rate ofthe individual virtual circuits. We also show that high goodputscan be achieved with more modest buffer sizes, but that EPDexhibits anomalies with respect to buffer capacity, in that thereare situations in which increasing the amount of buffering cancause the goodput to decrease. These results are validated bycomparison with simulation.


1996 - Analysis of an ATM Shared Buffer Switch Loaded with Bursty Traffic [Relazione in Atti di Convegno]
F., Callegati; Casoni, Maurizio; G., Corazza; C., Raffaelli
abstract

In this paper a modeling approach to performance evaluation of a shared buffer switching element is described, based on the well-known fluid model of producers and consumers (PC fluid model). A procedure is outlined that leads to a suitable characterization of some typical parameters of the producer and consumer fluid model, making it representative of the shared buffer switch. Simulation analysis is used to investigate the relationships between the behavior of the shared buffer switching element and of the PC fluid model. In the paper it is shown that by means of a suitable fitting of one parameter characterizing the PC fluid model, it is possible to make it representative of the shared buffer in the region of interest for ATM applications. This in spite of the actual operating differences between the real system and the PC fluid model. Numerical results regarding cell loss probability performance and dimensioning of 4 by 4 and 8 by 8 switches are presented and suitably discussed.


1996 - Simulation and Analytical Approximation of ATM Multistage Shared Buffer Switch [Relazione in Atti di Convegno]
Casoni, Maurizio; C., Raffaelli
abstract

A multistage ATM switch based on Clos interconnection of shared buffer switching elements is analyzed with the aim to develop design tools suitable for switch dimensioning in the range of ATM cell loss target. Starting from a simulation activity, which obtains the main switch performance and shows the effects of architectural and operational options, an approximated model is proposed. It is based on the discovery that statistical correlations in later stages of Clos network reduces so that it is feasible to treat different queue lengths as independent random variables to evaluate the cell loss performance of a shared buffer switching element. Approximate dimensioning of the whole switch is also performed. Results are given and verified in the range tractable by simulation for uniform and multiplexed bursty traffic


1996 - System Design and Evaluation of a Large Modular Photonic ATM Switch [Articolo su rivista]
J. B., Jacob; Casoni, Maurizio; G., Corazza; F., Masetti; P., Parmentier; C., Raffaelli
abstract

A photonic ATM switching node based on the Fibre Delay Line switching element developed in the framework of the RACE project ATMOS is described.