Intent-Based Networking (IBN) enables operators to specify high-level outcomes while the system translates these intents into concrete policies and configurations. As IBN deployments grow in scale, heterogeneity and dynamicity, ensuring continuous alignment between network behavior and user objectives becomes both essential and increasingly difficult. This paper provides a technical survey of assurance and conflict detection techniques in IBN, with the goal of improving reliability, robustness, and policy compliance. We first position our survey with respect to existing work. We then review current assurance mechanisms, including the use of AI, machine learning, and real-time monitoring for validating intent fulfillment. We also examine conflict detection methods across the intent lifecycle, from capture to implementation. In addition, we outline relevant standardization efforts and open-source tools that support IBN adoption. Finally, we discuss key challenges, such as AI/ML integration, generalization, and scalability, and present a roadmap for future research aimed at strengthening robustness of IBN frameworks.

Traditional 5G user plane function (UPF) architectures are software-based implementations that struggle to maintain performance. To meet the stringent quality of service (QoS) and scalability requirements of 5G under high session and data plane loads, a highly efficient next-generation UPF is required. In this paper, we present a next-generation 6GUPF that fully leverages the hardware acceleration of SmartNICs/DPUs. The 6GUPF is developed using DOCA Flow API, which enables fast, programmable packet processing directly in the data path, specifically for the N3 gNB network and N6 interfaces of datanet. The architecture integrates flow-based acceleration for stateful flow tracking and symmetric Receive Side Scaling (RSS) to utilize cores and manage non-blocking states efficiently. This will help minimize latency and avoid contention in multi-core environments. Our experiments show that hardware-offloaded UPF achieves an aggregate line rate of 400 Gbit/s, supports 1 million concurrent data streams, and scales up to 500,000 active User Equipment (UE) instances while maintaining QoS and session isolation. It also enables 40% lower latency compared to traditional software UPFs. Unlike Tofino-based P4 switch UPF designs, which are limited by SRAM and TCAM constraints when storing large-scale data streams, our DPU-based solution is ideal for high-density Protocol Data Unit (PDU) deployments without sacrificing programmability and performance. It creates a path for cloud-native, 6G UPF deployments that can scale to a wide range of workloads, from ultra-low-latency applications to large-scale IoT backhaul.

The fast-paced growth of 5G networks, along with the emergence of 6G technology, has emphasized the crucial importance of strong security measures to safeguard communication infrastructures. A key security issue in 5G data networks is Distributed Denial-of-Service (DDoS) at tacks, which specifically target the GTP-based protocol which is a significant threat. However, network telemetry data provides a rich source of information about the nature of network traffic, which can be used to detect and predict DDoS attacks. We propose a novel framework for collecting and processing large amounts of telemetry data in 5G networks leveraging state-of-the-art technologies, including data-plane programmability in P4-based User-Plane Function (UPF) and Data Processing Unit (DPU). Furthermore, we propose an anomaly-detection method for performing live deep learning analysis on network traffic using a Convolutional Neural Network (CNN) to detect DDoS attacks. Our results demonstrate the effectiveness of our framework, achieving an impressive 98.6% accuracy and 98% F1-score.

Next-Generation Radio Access Networks (NG-RANs) aim to facilitate high data rates, low-latency applications, and dense mobile connectivity — benefit from the integration of Artificial Intelligence and Machine Learning (AI/ML) to enhance performance and efficiency. Nevertheless, the dynamic service demands within NG-RAN (namely Open RAN) lead to AI/ML performance degradation known as drift, resulting in violations of Service Level Agreements (SLA) and issues like over-or under-provisioning of resources. Detecting and adapting to drift becomes crucial to meet the diverse requirements of intelligent networks. Due to frequent retraining, the existing threshold and classifier-based approaches have potential disadvantages such as SLA violations and resource inefficiency. This paper introduces a novel approach that exploits the Generative Adversarial Network (GAN) architecture to determine the drift and anomaly. The proposed approach is evaluated for a throughput prediction use case over a real-time dataset and compared to the threshold and classifier-based approaches. The results show that the proposed approach outperforms the threshold and classifier-based approaches.

The widespread connectivity provided by fixed and mobile communication technologies can facilitate the utilization of e-health and mobile-health services that are radically changing the way healthcare may be provided. Such services are particularly important for inner areas, where it is difficult to guarantee physical availability and proximity of services while ensuring the sustainability of the system. However, e-health and m-health service deployment requires careful planning, as connectivity in inner areas can be spotty. This paper reports how multiple e/m-health solutions have been planned in some inner areas of Tuscany within the PROXIMITY-CARE project. In particular, it introduces a newly developed QGIS-based analysis tool, which allows correlating connectivity data with patient needs and healthcare facilities location. Moreover, the paper presents a tele-tutoring system for the emergency service and a mobile application to monitor patient vital parameters. Such tools facilitate the maximization of the reached population, thus improving benefits for the patients.

This research aims to propose an approach to address the unpredictability topology state issue of FANET. The mobility of the network can lead to frequent link disruptions, causing communication unavailability. To mitigate this, our goal is to implement an AI algorithm that can identify patterns in UAV mobility, predict potential disconnections, and trigger rerouting/forwarding algorithms in advance. This paper presents an example of an SD-FANET able to provide wireless in-band telemetry to the AI-equipped edge node placed at the ground station, discusses the design of subsystems hosting the AI process, and demonstrates how a machine learning model can recognize critical network situations without relying on complex neural networks.

Intent-based Networking (IBN) has emerged as an innovative approach to automate the provisioning of network services while abstracting the details of the underlying infrastructure and simplifying the interaction between the users and the network. In this paper, we present an intent-based framework that allows for the deployment of SDN-based and QoS-aware network slices. The main objective of the work is to describe the role of artificial intelligence techniques such as Natural Language Processing (NLP) and user profiling in helping non-expert users easily interact with the IBN system and express their desired operational goals. Such innovative solutions offer a customized support to the users to improve their Quality of Experience (QoE) while increasing the automation in the network configuration process.

Beyond fifth-generation (B5G) networks (namely 6G) aim to support high data rates, low-latency applications, and massive machine communications. Integrating Artificial Intelligence (AI) and Machine Learning (ML) models are essential for addressing the network’s increasing complexity and dynamic nature. However, dynamic service demands of B5G cause the AI/ML models performance degradation, resulting in violations of Service Level Agreements (SLA), over-or under-provisioning of resources, etc. To address the performance degradation of the AI/ML models, retraining is essential. Existing threshold and periodic retraining approaches have potential disadvantages such as SLA violations and inefficient resource utilization for setting a threshold parameter in a dynamic environment. This paper presents a novel algorithm that predicts when to retrain AI/ML models using an unsupervised classifier. The proposed predictive approach is evaluated for a Quality of Service (QoS) prediction use case on the Open RAN Software Community (OSC) platform and compared to the threshold approach. The results show that the proposed predictive approach outperforms the threshold approach.

The recent availability of smart network interface cards (smart NICs) and Data Processing units (DPUs) providing hardware-accelerated networking and computing functionalities is opening the way towards new applications and use cases beyond the traditional data center scenarios. In this paper, three different use cases for edge scenarios that leverage on the innovative programmability enabled by DPUs are presented and discussed. The first use case focuses on a pervasive monitoring infrastructure to support accurate and decentralized network awareness for low-latency 5G services. The second one focuses on the implementation of power-efficient edge-to-cloud continuum. The third use case refers to effective network security functions at the DPU.

The advent of Open Radio Access Network (O-RAN) technology enables intelligent edge solutions for base stations in beyond 5G (B5G) networks. O-RAN Working Group 2 (WG2) focuses on the architecture and specifications of AI/ML workflows, allowing AI/ML applications in O-RAN environments to meet different QoS requirements for different use cases over varying time periods. This study shows the technical challenges in mapping AI/ML functionalities at Near-Real Time (RT) RAN Intelligence Controller (RIC) and/or Non-RT RIC for closed loop control-based resource adaptation in O-RAN. We also present a drift-based solution to avoid performance violations if there is decay in prediction accuracy. Results show that drift-based solution outperforms offline models.

Network programmability based on the P4 language is gaining consensus in multiple scenarios, including edge computing. In this work, we present the P4-based edge networking solutions adopted in the framework of the EU-funded BRAINE Project. The project targets the design and development of a powerful edge micro data center (EMDC) aiming at boosting artificial intelligence (AI) at the network edge. The EMDC will encompass an embedded programmable P4 ASIC supporting unprecedented intra- and inter-edge/fog interconnection. In this paper, a selection of the solutions to be supported by the P4 switch embedded within the BRAINE EMDC is presented. They include decentralized traffic engineering solutions driven in-band telemetry (INT), quality of service enforcement and verification, 5G network function virtualization, and decentralized cyber-security at the edge.

Vertical industries are attracted by the flexibility and customization offered by network operators through network slicing to run their application platforms in virtual infrastructure assets tailored to their needs. On the other hand, in addition to the desired virtual capacity and component network functions into the slice, verticals may also want to specify connectivity and QoS slice requirements in abstract terms and without dealing with details of network service descriptors and technicalities of the underlying infrastructure.In this work, we propose an intent-based QoS-aware and SDN-enabled slicing implementation that allows customized specifications and establishment of network slices toward flexible delivery of vertical services. The aim is to simplify and automate the deployment of the network slices through a declarative approach while unburdening verticals to deal with technology-specific low-level networking directives. The paper focuses on the implementation of the intent layer using an ETSI NFV MANO platform and presents preliminary experimental results assessing the feasibility and effectiveness of our approach.

From tenant (i.e., vertical) perspective, one of the attractive feature of network slices is the possibility to use SDN solutions, i.e., network programmability, to facilitate dynamic connectivity in the slice of the application software components in a flexible and scalable way. In this paper, we present an automated deployment of tenant-managed SDN network slices that allows network operators to enhance the service offerings, and tenants to benefit of in-built SDN capabilities. The SDN slice is built as a Network Service automatically deployed by Open Source MANO as a set of VNFs dynamically configured as SDN nodes (switches and controller) connecting tenant software components. We describe how to automatically and programmat-ically set-up SDN capabilities in the slice through the use of Juju Charms and provide some preliminary performance results.

In the context of sport assessment, the evaluation and monitoring of the referees decisions is of interest for several sports in order to avoid disputes and assist the referees in their activity. Some current solutions are based on video recording, third referee, etc. In this paper, a new wireless wearable system, result of the Italian research project REC-VISIO, is described suitable to assess the referees actions when they are on the move. The system is able to collect the referee staff visual perspective of a sport match, whose subjective is recorded, preprocessed and sent by a wireless network to a sideline workstation for final stabilization. The system architecture design and implementation are described along with the experimentation on the field, considering as use case a football match. The experimentation has shown the successful integration of all the different system components, where the cooperation of sensor-based subsystem, processing unit, and communication subsystem allows to collect and stabilize the video streaming reducing the effects of the movement of the referee, and send in real-time the video content to the sideline workstation without video quality degradation.

The Open Computing Language (OpenCL) is increasingly adopted for programming processors with reconfigurable hardware acceleration. The 5G telecommunication infrastructure, imposing strong latency constraints on the managed communications, may benefit from OpenCL-designed accelerated processing. This paper presents the first study to evaluate OpenCL hardware acceleration in the context of a 5G base station physical layer. The implementation and optimization process to accelerate the Orthogonal Frequency Division Multiplexing (OFDM) part of the 5G downlink is conducted on a high-end Field Programmable Gate Array (FPGA). We show that the proposed OpenCL implementation complies with the 5G processing timing requirements since the computation time is consistent with the present 5G deployment. However, to be suitable for 5G, the OpenCL platform must improve the data latency transfer between hardware and software. Moreover, a further enhancement for the OpenCL implementation is to improve the code by means of OpenCL optimization techniques. In this way, the performance can be further improved with respect to optimized software on vectorized high-end processors.

The fifth generation of mobile communications (5G) is expected to dramatically improve performance compared to preceding standards by offering very high bandwidths and low latencies. To provide this performance, heavy processing is required and must meet strong timing constraints. Reconfigurable computing, managing processing in software and exploiting reconfigurable hardware acceleration, is an innovative approach that should be considered for 5G for its capacity to combine high throughput and high flexibility. This paper presents a case study for Orthogonal Frequency Division Multiplexing (OFDM) computation reconfigurable offloading onto an Field Programmable Gate Array (FPGA). The implementation is based on Open Computing Language (OpenCL) that represents a versatile solution, as this language can be compiled for several architectures, provided that a Host+Accelerator structure is used. The objective of our study is to demonstrate that, by means of hardware offloading, the 5G architecture resources can reach high computational load, avoiding processing stalls and latency increase. Results show that around 15% of the software processing can be freed through hardware acceleration and reallocated to support other tasks.

In this demo we show the functionalities of the Open Source MANO extended with advanced authorization capabilities able to enhance the security support in terms of preservation of virtual resources and slices integrity in a dynamic context of users, services and resources. The presented extension consists of a Usage Control System integrated with Open Source MANO enhancing traditional authorization operations with ongoing usage control on established slices, virtual resources and user behaviour by continuously reconsidering the granting of resources in light of mutable attribute of users, resources and environment (e.g., presence of viruses, set-up of weak passwords).

Due to the impressive demand for communication-intensive applications deployed in the cloud, cross-layer orchestration solutions for Cloud data centers (DCs) are essential for the effective usage of both network and cloud resources while addressing service requirements and user expectations. In this regard, the software-defined networking (SDN) can play a key role thanks to programmable network control operations and to a more effective inter-working between network controllers and cloud management platforms. On the other hand, due to the relevant size of Cloud DCs, a significant evaluation of SDN-based orchestration solutions requires testing environments with proper scales, and significant level of fidelity. This paper discusses the opportunities of using virtual testbeds to carry out Cloud-related experimentations while addressing with significant scale requirements of DC infrastructures. First, we present a set of results of a test campaign we carried out using the Fed4FIRE experimental facility aiming at a comprehensive performance evaluation of an SDN-based orchestration solution for Cloud DCs. Second, we provide a comparison between virtual testbeds and other testing environments, i.e., laboratory testbeds, simulators and emulators, in terms of offered advantages, and effectiveness in experimentations. Moreover, we discuss the appropriateness and advisability of using virtualized testbeds for research on novel SDN and Cloud orchestration solutions at scale, by highlighting advantages of virtual testbeds in comparison with laboratory, simulation and emulation testing facilities in terms of effectiveness of experimentations and accuracy of results.

The spreading diffusion of wireless devices and the crowded coexistence of multimedia applications greedy of bandwidth and with strict requirements stress the service provisioning offered by wireless technologies. WiFi is a reference for wireless connectivity and it requires a continuous evolution of its mechanism in order to follow increasingly demanding service needs. In particular, despite the evolution of physical layer, some critical contexts, such as industrial networks, telemedicine, telerehabilitation, and virtual training, require further refined improvements in order to ensure the respect of strict real-time service requirements. In this paper an in-depth analysis of Dynamic TXOP HCCA (DTH) MAC enhanced centralized scheduler is illustrated and it is further refined introducing a new improvement, DTH with threshold. DTH and DTH with threshold can be integrated with preexisting centralized schedulers in order to improve their performances, without any overprovisioning that can negatively impact on the admission control feasibility test. Indeed, without modifying the centralized scheduler policy, they combine together the concepts of reclaiming transmission time and statistical estimation of the traffic profile in order to provide, at each polling, an instantaneous transmission time tailored to the variable traffic requirements, increasing, when necessary, the service data rate. These mechanisms can coexist with advanced physical layer-based solutions, providing the required service differentiation. Experimental results and theoretical analysis, based on elastic scheduler theory, show that they are effective especially in the case of Variable Bit Rate traffic streams in terms of transmission queues length, packets loss, delay, and throughput.

In this paper, we present an experimental set-up reproducing a convergent 5G service scenario spanning over SDN-based Edge network, Cloud and IoT domains. To address reliability and robustness requirements of future 5G networks, the set-up also includes an SDN orchestrator able to adaptively provision data delivery paths connecting service components running in those different domains. In particular, we demonstrate SDN orchestration capabilities in adapting data paths across IoT, Cloud and network domains based on the real-time load state of switches thereby recovering from congestions and assuring reliable data delivery services.

The promise of SDN/NFV to offer enhanced functionalities to the service provider networks is now tangible as both technologies have started being steadily investigated and experimentally demonstrated. However, a number of research challenges have not been fully addressed yet. More specifically, a limited interest has been devoted on how to assure reliability and QoS performance while data traverse service chain paths. In this work, we present an SDN orchestrator that periodically evaluate the availability status of the network and, accordingly, adapt service chain paths to recover from congestion events and to preserve QoS performance thus avoiding SLA violations. A prototype is presented along with a performance evaluation of the orchestrator in terms of improved data transfer capabilities against the cost of path adaptations and the controller overhead.

Incorporating energy efficiency into the design of modern communication systems has become an important area of research. However, while most of the proposed solutions are devoted to making network hardware energy efficient, very few works focus on energy efficiency as a fundamental design parameter of network protocols. This paper proposes an analytical model for energy consumption of TCP which relates energy consumption to protocol operation cycles. Based on this model a number of optimization techniques are proposed to reduce energy consumption of TCP. The experiments, performed using NS2 simulations, demonstrate that energy savings can be as high as 93% for multiple TCP flows.

We present an SDN-based orchestration system that enables automated and coordinated arrangement of both computing and network resources in virtualized DC environments. The orchestrator is validated through a set of simulations, as well as through experiments carried out in a real laboratory. Results show that the proposed orchestration system improves the service requests acceptance rate and the utilization of network resources, while minimizing degradations of the user experience. Thus, DC resources can be effectively exploited, and different management objectives (e.g., load balancing, energy saving) can be reached.

The utilization of Ethernet in the cellular terrestrial cloud radio access network (C-RAN) fronthaul is considered as a way for improving C-RAN network reconfigurability and efficiency in terms of both capital and operational expenditures. Moreover CPRI line bit rate dynamic reconfiguration may spare further capital expenditures by avoiding a peak traffic capacity allocation. A possible solution for introducing Ethernet in the fronthaul is the encapsulation of Common Packet Radio Interface (CPRI) over Ethernet. However, it must be assured that CPRI strict requirements on delay and jitter are still met. In this work the combined impact of encapsulating CPRI on Ethernet and of the dynamic CPRI line bit rate reconfiguration on delay and jitter is evaluated. The evaluation is both analytical and based on the pre-synthesis emulation of dynamic CPRI line bit rate reconfiguration. Results show that dynamic CPRI line bit rate reconfiguration can be achieved within about one millisecond. However, if a size-based encapsulation of CPRI over Ethernet is utilized, dynamic CPRI line bit rate reconfiguration might cause delay variations (i.e., jitter) up to few microseconds.

Segment Routing (SR) is emerging as an innovative traffic engineering technique compatible with traditional MPLS data plane. SR relies on label stacking, without requiring a signaling protocol. This greatly simplifies network operations in transit nodes. However, it may introduce scalability issues at the ingress node and packet overhead. Therefore, specific algorithms are required to efficiently compute the label stack for a given path. This study proposes two algorithms for SR label stack computation of strict routes that guarantee minimum label stack depth. Then, SR scalability performance is investigated. Results show that, in most of the cases, SR uses label stacks composed of few labels and introduces a limited packet overhead. However, relevant scalability issues may arise in specific cases, e.g., large planar topologies.

In TWDM-PON, the utilization of tunable transceivers at the ONUs allows to dynamically reconfigure the OSU-ONU pairings to decrease, for example, the energy consumption at the OLT. However, if the utilized dynamic wavelength and bandwidth allocation (DWBA) does not take into account which ONUs are reallocated, the ONU tuning overhead can severely impact the average frame delay experienced by the tuning ONUs. The paper shows that, by alternating the ONUs that tune at each reconfiguration, the impact of ONU tuning overhead on average frame delay is fairly distributed among the ONUs.

Elastic Optical Networks will drive a high degree of flexibility enabling dynamic configurable lightpaths provisioning and re- optimization due to next generation bandwidth variable transponders and switches. In order to guarantee quality of transmission (QoT), novel Operation Administration and Maintenance (OAM) solutions are necessary with respect to existing standard management protocols. For optical networks, scalable mechanisms providing fast and effective QoT alarm information, including localization and, possibly, forecasting critical events, are needed. The introduction of the Application Based Network Operation (ABNO) architecture is pushing towards a dedicated OAM Handler, in charge of collecting OAM information from the network, performing correlations and triggering control plane reaction. However, serious scalability issues may arise since a centralized element would have to elaborate a potentially huge amount of data. In this paper, a novel hierarchical OAM architecture is proposed, that enables multi- level OAM entities to provide OAM Handler with effective information, obtained by filtering several OAM messages at each layer, so that the overload of OAM Handler is avoided. Moreover, the NETCONF protocol, typically used for SDN- based node configuration purposes, is proposed and utilized as OAM protocol, in order to achieve high degree of convergence and limit the number of utilized protocols. The proposed OAM architecture is implemented and experimentally evaluated in a QoT degradation use case, showing that multi-level localization and local correlation of events allow aggregated, fast and scalable OAM information set provided to the OAM Handler.

When traffic carried by a Time and Wavelength Division Multiplexed (TWDM) PON is fluctuating, the network performance, both in terms of energy efficiency and delay, is heavily impacted by the decision of when network reconfiguration (i.e., switching OSUs from active mode to sleep mode and vice versa) is triggered. This paper provides hints on when to trigger a network reconfiguration is such scenario by considering also the ONU tuning time. Results show that reconfigurations shall follow as soon as possible traffic variations. However, if traffic variations are fast, the ONU tuning time impairs delay performance. Therefore, when traffic variations are fast, it is better not to reconfigure the network at the expense of a higher energy consumption.

The adoption of the virtualization paradigm in both computing and networking domains portends a landscape of heterogeneous service capabilities and resources pervasively distributed and interconnected and deeply integrated through the 5G network infrastructure. In this service ecosystem, dynamic service demand can be flexibly and elastically accomplished by composing heterogeneous services provisioned over a distributed and virtualized resource infrastructure. Indeed, with the term Virtual Functions we refer to virtual computing as well as network service capabilities (e.g., routers and middlebox functions provided as Virtual Network Functions). In order to cope with the increasingly resource intensive demand, these virtual functions will be deployed in distributed clusters of small-scale datacenters typically located in current exchanges at the network edge and will supplement those deployed in traditional large cloud datacenters. In this work we formulate the problem of composing, computing and networking Virtual Functions to select those nodes along the path that minimizes the overall latency (i.e. network and processing latency) in the above mentioned scenario. The optimization problem is formulated as a Resource Constrained Shortest Path problem on an auxiliary layered graph accordingly defined. The layered structure of the graph ensures that the order of VFs specified in the request is preserved. Additional constraints can be also taken into account in the graph construction phase. Finally, we provide a use case preliminary evaluation of the proposed model.

Recent advances in network control and management technologies, such as software defined networking (SDN) and network function virtualization (NFV), are expected to make the network effectively able to cope with application service requirements in a more flexible and timely manner. We argue that SDN and NFV capabilities can be exploited in Next Generation Service Overlay Networks (NGSONs) for addressing contex-aware end-to-end data delivery services with adaptive composition of middlebox services when dynamically provisioned as virtual functions. In this paper we present a Service-Oriented SDN controller that allows for the programmable provision of data delivery paths through a dynamically established sequence of virtual middlebox functions, thereby accomplishing the deployment of adaptive network service chains in NGSON. In this way, an extended set of QoS requirements can be addressed that include specifications on processing functions to be traversed by service data while taking advantages from context-awareness and self-adaptation capabilities of NGSON. A use case analyis have been carried out on an experimental testbed about the effectiveness of the proposed approach in differentiating service data processing while optimizing the use of forwarding tables in the switches.

This paper proposes an advanced sleep-aware dynamic bandwidth allocation (ASDBA) scheme for 10G-EPONs that aims to maximize ONU energy efficiency with sleep mode. In the proposed ASDBA scheme, both upstream (US) and downstream (DS) transmissions are scheduled in the same transmission slot whose duration is minimized based on both DS and US bandwidth requests and the ONU transceiver is switched off outside the slot for saving energy. The ASDBA swaps the conventional order of control message exchange utilized in legacy 10G-EPON to convert the ONU idle time between a REPORT message and its replying GATE message into ONU sleep time. This enables the ONU to sleep continuously after sending a REPORT message until the beginning of the next transmission slot, further improving ONU energy-savings. Results show that the proposed scheme significantly saves ONU energy whilst incurring acceptable frame queuing delays.

Nowadays, Data Centers are the primary infrastructures for Cloud Computing services provisioning. In this challenging scenario, Data Centers have to deal with highly dynamic workloads, thus not only should they adopt advanced software virtualization solutions, but also network control capabilities. Elastic, agile network connectivity control should be integrated with the computing management infrastructure to make it achieve its goals. This paper presents an OF-based controller, called OFVN, that enables novel virtualization-aware networking functions in Cloud DCs. Virtual Machines allocations are performed considering the availability of computational resources on physical server, but also selecting a forwarding path for VMs data flows based on network links utilization. The focus of the paper is on the implementation and assessment of the controller in an experimental testbed. The behaviour of different allocation strategies is also investigated.

Path Computation Element (PCE) architecture enables effective traffic engineering in multi-domain networks while limiting the exposure of intra-domain information. However, returned path computations might reveal confidential information if artfully correlated by a malicious PCE. Thus, the selection of domains sequence as the result of PCEs cooperation should depend not only on the capability of providing quality paths but also on factors related to expected revenues or perceived risks. In this scenario, cooperation among PCEs could benefit from a trust model by evaluating the quality of the past interactions. This work introduces the concepts of Quality of Interaction and trust ranking and elaborates a trust management model including effectiveness and security objectives regulating the cooperation among PCEs. Specifically, the proposed trust model aims at stimulating effective interactions among PCEs as a result of a common interest in contributing to successful and profitable path computations while avoiding misuse of path computation services. The simulation results show that our trust model is effective in detecting malicious PCE thereby tuning the amount of information returned in the path computation replies.

Oversubscription of intra-Data Center network links and high volatility of VM deployments require a flexible and agile control of Data Center network infrastructures, also integrated with computing and storage resources. In this scenario, the Software-Defined Network paradigm and, specifically, the OpenFlow protocol, opens up new opportunities for the design of innovative resource management platforms that enable dynamic and fine-grain control of DC networks through traffic engineering algorithms. This paper investigates the performance of two different sets of cloud-fluent traffic engineering algorithms. Conceived to work during cloud service deployments, the main target of such algorithms is to achieve a better utilization of network resources by exploiting OpenFlow capabilities for traffic-aware deployments of Virtual Machines. The effectiveness of the proposed solutions is evaluated in terms of network link utilization against VM requests acceptance ratio through simulations and experimental tests carried out by using an ad-hoc emulator.

This demo deals with a new orchestrator, the OFVN controller, specifically designed, according to the SDN principles, to deliver Cloud services with IT and network resources requirements.

This paper presents the experimental evaluation of an energy-efficient TDMA PON utilizing cyclic sleep technique. In particular, two methods for deciding when to trigger ONU sleep mode are evaluated: downstream (DS)-based triggering and Cooperative triggering. In the former method, the decision whether the ONU is switched to sleep is taken based on the DS traffic only. In the latter one, the decision is taken by considering both DS and upstream (US) traffic. The performance is assessed with constant sleep time as well as variable sleep time for different DS/US traffic ratios. Experimental results show that both triggering methods achieve significant energy savings. The Cooperative saves slightly less energy than the DS-based while providing better network performance, in terms of frame loss rate and frame delay, for both DS and US traffic.

The International Electrotechnical Commission (IEC) recently standardized several Industrial Ethernet solutions that introduce the fieldbus concepts within Ethernet based networks. In addition, the IEC 62439 standardized a set of redundancy management protocols, including the Media Redundancy Protocol (MRP). In this way, IEC standards provide a variety of Ethernet-based solutions for satisfying both temporal and redundancy management requirements of Industrial Area Networks (IANs). In this paper, after a detailed study and implementation of MRP, two factors are identified that have an important impact on the protocol performance: the offset time and the physical detection time. A method is then provided to calculate a threshold to the network recovery time. Finally, extensive simulations and experimental measurements are performed to accurately evaluate the effect of the aforementioned factors on the protocol performance.

The need to preserve information confidentiality among network providers has prevented the actual deployment of effective Traffic Engineering (TE) solutions for QoS-enabled end-to-end connectivity services in multi-domain multi-provider networks. The use of Path Computation Element (PCE) architecture can foster the effective implementation of TE through a centralized engine devoted to end-to-end path computations. However, despite authentication, authorization and encryption, confidentiality issues may arise due to abuses of information included in path computation replies to bogus requests issued by malicious PCEs. This paper first demonstrates the security leak allowing the exposure of intra-domain information in current inter-PCE path computation procedures. Then it proposes an anomaly-based approach, namely PCE Anomaly Detector (PAD) in order to detect malicious utilization of path computation services. The proposed PAD employs a novel double-step multi-dimensional formulation based on the Sequential Hypothesis Testing (SHT) statistical classification procedure, able to recognize a suspicious sequence of requests while aiming at inferring confidential information about other domains. PAD is extensively evaluated through simulations. Results show good performance in terms of detection capabilities while guaranteeing the trade-off between accuracy and responsiveness, minimizing false alarm occurrences. Robustness against smart attacks is also proved with respect to a comprehensive set of attack patterns and under different network load conditions. Finally, intra-domain information exposition is evaluated, showing the PAD ability to preserve confidentiality.

In flexi-grid optical networks, effective defragmentation (i.e., re-optimization) solutions are required to efficiently exploit network spectrum resources. However, current defragmentation solutions can only be implemented thanks to the presence of additional resources, such as spare extensive transponders. In this study, focusing on optically-amplified direct-detection systems, we experimentally demonstrate the feasibility of a novel defragmentation technique, called push-pull, based on dynamic lightpath frequency retuning upon proper reconfiguration of allocated spectrum resources. The technique does not require additional transponders and does not determine traffic disruption. All the relevant technological limitations that may affect the push-pull applicability are discussed. A simple yet effective closed-form expression is also proposed and experimentally validated to assess the maximum retuning range in a single push-pull operation, such that the quality of transmission during defragmentation is safely guaranteed. The technique is then successfully demonstrated in a flexi-grid network testbed. In particular the reoptimization of one lightpath is safely completed in few seconds (mainly due just to node configuration latencies) without experiencing any traffic disruption.

The joint management of IT and network resources is a key aspect for dynamic inter-data center interconnection networks designed to work according to the cloud computing paradigm. Such a scenario calls for the anycast routing of service requests to find a data channel that best suits both connectivity and IT resource requirements. This paper presents different network resource allocation and release policies across an inter-data center interconnection network aimed at a balanced accommodation of network resources to improve performance. Such policies are evaluated and compared in terms of service set-up blocking probability considering also configuration latency of real network devices that play a significant role along with network bandwidth availability across the network. Results show that the best choice is to release network resources as soon as possible, even though this means increasing the service blocking due to network reconfiguration latency.

Power consumption in access networks is becoming a relevant issue. Strategies for reducing the power consumption (such as sleep mode support) and enhancing the energy proportionality have been recently proposed and also introduced in the standards for access networks based on time division multiplexing (TDM).

Inter-domain traffic engineering solutions based on the Path Computation Element (PCE) architecture are exposed to information confidentiality issues between network carriers. Licit PCE Protocol (PCEP) request sequences may hide a malicious intention to discover critical intra-domain information through correlations among replies. This work presents an innovative anomaly-based statistical approach based on the Sequential Hypothesis Testing (SHT) aiming to detect malicious utilization of PCEP by peer clients. A novel combined multi-feature SHT formulation is presented in combination with different decision policies for definitely ascertaining whether the behavior of the Path Computation Client (PCC) is malicious or not. Simulation results show improved performance in terms of detection and falsealarms probabilities while guaranteeing a trade-off between detection accuracy and delay.

Estimates indicate that about 80% of the power consumption of cellular networks must be supplied by operators. It is thus becoming of paramount importance to improve the energy efficiency of cellular networks at the operator side for an economic and environmentally-sustainable traffic growth. The introduction of discontinuous transmission - or sleep mode - at the base stations can enable a reduction of power consumption. To further enhance the reduction, this paper proposes to coordinate the sleep scheduling among neighboring cells. The sleep schedule coordination allows the inter-cell interference reduction, during the sleep periods. This paper assesses the performance of different sleep schedules (uncoordinated, coordinated orthogonal and coordinated partially-orthogonal) applied to cellular networks based on Long Term Evolution (LTE) protocol. Simulation results show that only by coordinating the sleep schedules it is possible to significantly improve the throughput and the energy efficiency. In particular, the coordinated orthogonal sleep schedule is able to reduce the energy consumption by over 80%, achieving a gain of about 13%.

Space switches are the fundamental elements in single plane and multi-plane optical interconnection networks. This paper proposes a heterogeneous implementation of optical space switches based on two gating elements, amplifiers such as semiconductor optical amplifier (SOA) and modulators such as Mach-Zehnder modulators. The heterogenous implementation has the advantage of being more power-efficient than a homogeneous implementation based only on SOAs and more scalable than a homogeneous implementation based only on modulator-based gates as the optical power loss can be compensated by the SOAs. The paper derives the requirements in number of gating elements for different space switch architectures (i.e., crossbar, Beneš, Spanke, Clos, Spanke-Benes, and hybrid Clos). Based on the such derivation, the scalability and the power-efficiency of the different non-blocking architectures with heterogeneous design are assessed, with the aim at identifying the most suitable architecture based on today's available optical technologies. Results show that power saving around 80% are achievable when using a heterogeneous implementation instead of a homogenous SOA-based implementation.

In wavelength switched optical networks (WSON), quality of transmission (QoT) can be guaranteed by regenerating the optical signal in intermediate nodes. Regeneration can also offer wavelength conversion. When only few regenerators are placed in the WSON, the main issue is to optimally select the nodes where regeneration and wavelength conversion should take place. This paper proposes a distributed strategy for joint selection of wavelengths and regeneration locations (points) in a dynamic WSON with GMPLS control plane. To support the strategy, extensions to the RSVP-TE protocol are proposed. Simulation results show a significant improvement of the connection blocking and fairness, as well as a reduced amount of used regenerators in the network compared with existing strategies, which are based on disjoint and non- distributed resource selection.

This work presents a signaling framework for the Future Internet capable of enabling unified network and IT resource allocation. The proposed signaling scheme is based on existing technologies and carried out through extensions to protocols already operated in current Internet, i.e., SIP, and by resorting to source-initiated GMPLS signaling without introducing network technology- dependent mechanisms. The experimental validation presented in this work has been carried out on a real test-bed. Performance of the service set-up procedure are reported taking into account the response time of real life devices such as commercial routers and protocols. The results provided show that the architecture proposed is compliant with conventional performance levels such as those set by the ITU- T. Finally, scalability performance have been verified by stressing the system with increasing rate of simultaneous service requests.

In Wavelength Switched Optical Networks (WSONs), sharing of protection wavelengths is an attractive strategy to increase survivability against failures. However, to guarantee an acceptable quality of transmission (QoT), both working and protection paths may need to undergo optical-electrical-optical (OEO) regeneration. With this aim, the placement of a limited number of regenerators is a cost-effective solution to guarantee QoT. In this paper, the concept of sharing the protection resources is extended to regenerators. Moreover, shared regenerators can be exploited for ensuring QoT as well as for providing wavelength conversion. The main objective of this paper is the study of different strategies for the selection of regenerators and wavelengths in WSON with a GMPLS-based distributed control plane. Simulation results show a trade-off between the strategies achieving a high wavelength sharing and those achieving a high regenerator sharing.

Energy-efficient optical networks are gaining momentum as environmental-friendly solutions with reduced operational costs. Energy-efficiency can be achieved by using devices in sleep mode, i.e., a low-power, inactive state in which devices can be suddenly waken-up upon occurrence of triggering events. This paper advocates a sleep mode option for the optical devices (e.g., amplifiers, optical switches) installed for protection purposes only. These devices can be put in sleep mode to reduce the network power consumption, but they can be promptly waken up (if necessary) upon a failure occurrence. This principle is proposed and applied in Wavelength Division Multiplexing (WDM) networks with dedicated-path protection to ensure survivability against single-link failures. The main contribution of the paper is the definition of the energy-efficient network planning problem for resilient WDM networks where optical devices can be configured in sleep mode. Optimal results of the integer linear programming (ILP) problem show savings of up to 25% in the overall power consumption.

Sharing of protection resources is a cost-effective solution to guarantee survivability against failures. In wavelength-switched optical networks (WSON), in addition to sharing the wavelengths resources, wavelength converters (WCs) can also be shared by different optical connections, or lightpaths. This paper considers the problem of ensuring 100% survivability against single-link failures in a GMPLS-enabled optical network. RSVP-TE signalling protocol extensions for wavelength sharing under Shared Path Protection have been recently proposed for networks with wavelength continuity constraint. In this work, the performance of the proposed extensions is evaluated in a network with limited wavelength conversion. Furthermore, new extensions are proposed for an efficient WC sharing and their impact on the resource sharing is evaluated by simulations. Results indicate a trade-off between providing high wavelength sharing (i.e., low wavelength overbuild) and good WC sharing.

In multi-domain multi-carrier networks the effective use of network resources shall be achieved while guaranteeing an adequate level of confidentiality and scalability. A candidate solution to perform effective multi- domain Traffic Engineering (TE) is based on a combination of (i) hierarchical routing and (ii) path computation procedures. Hierarchical routing identifies the domain sequence to cross while path computation computes the strict end to end path. In this multi-domain study we first propose a hierarchical instance of BGP (HBGP) dedicated to TE information only. Then we propose and evaluate the integration of HBGP with path computation procedures based on IETF PCE architecture. Simulation results show that the hierarchical HBGP-PCE architecture, compared to current routing solutions based on BGP only, significantly improves the overall network resource utilization. In addition, this study identifies the network scenarios in which the aforementioned HBGP-PCE features provide significant advantages. Finally, the experimental implementation of the proposed HBGP-PCE architecture in a network testbed composed of commercially available routers shows the viability of the solution in real networks.

In GMPLS-controlled wavelength switched optical networks (WSONs), the RSVP-TE signaling protocol is utilized to reserve resources during both lightpath provisioning and dynamic restoration. During restoration, a number of reservation instances are contemporarily triggered by the failure. In such dynamic conditions, resource contention is the main blocking source. Several distributed solutions to reduce the impact of resource contention have been proposed that utilize advanced signaling mechanisms extending the RSVP-TE protocol. Conversely, this paper proposes two centralized solutions based on the Path Computation Element (PCE) that is used to coordinate the dynamic restoration of disrupted lightpaths with the specific aim of reducing resource contentions. Simulation results show that the utilization of the PCE during restoration reduces the blocking at the expenses of an increased recovery time with respect to distributed solutions. In addition, if the PCE is utilized together with the aforementioned advanced signaling mechanisms, the blocking can be further reduced.

We recently proposed the two-step scheduling framework (TSS) for multi-card optical switches: first, input ports on each card are assigned a different wavelength, then for every wavelength a matching is found among all cards. The proposed framework significantly improves the scheduler scalability and seamlessly adheres to the modular switch architectural constraints. In this paper TSS is evaluated from both the complexity and performance standpoints. The complexity analysis demonstrates the advantages of TSS in terms of required signaling and performed operations compared to a classical single-step scheduler. The performance analysis is conducted under non-uniform traffic, i.e., with a packet distribution highly skewed toward specific source-destination pairs. TSS latency using heuristic scheduling algorithms is shown to increase, compared to the one using computationally intensive optimal algorithms, especially at high loads. To counteract this issue, the transfer speedup technique is exploited, which allows to send more than one packet within a switching interval, while issuing a single scheduling decision. Results on different switch configurations demonstrate that the smallest transfer speedup allows TSS using suboptimal algorithms to achieve performance comparable to using optimal ones.

Current interconnection architectures based on electronics are approaching their physical limitations especially in terms of interconnection wiring and power density. To overcome these issues, the flexibility and the scalability of optical technologies can be exploited. This paper considers a modular optical interconnection architecture that consists of multiple cards, supporting a fixed number of ports and interconnected through a passive optical backplane. A two-step scheduling framework (TSS) is proposed, which exploits the modularity of the architecture and the existing scheduling algorithms, while satisfying the peculiar scheduling constraints of the architecture. In TSS, an intra-card step decides the wavelength switching configuration and then an inter-card step decides the space switching configuration. Each step can be run in parallel, on the cards and on the wavelengths, respectively. TSS is compared against a single-step scheduler suitable for non-modular architectures, under different traffic patterns and architecture configurations. TSS performs better in terms of lower packet delay, higher throughput and lower computational complexity. Finally, the possibility of increasing the packet transfer rate (transfer speedup) can be included in TSS without additional complexity and is especially beneficial for the bursty and skewed traffic patterns, typically experienced in real scenarios.

In this paper we evaluate the complexity and the performance of two different schedulers for high-speed optical switches with a large number of ports. We compare the classical approach with a two-step scheduling framework recently proposed for multi-card optical switches in which firstly transmitter

The connection-oriented nature of IEEE 802.16 (WiMAX) protocol facilitates the handling of quality of service (QoS). In IEEE 802.16 (WiMAX) networks, QoS-guaranteed connections, also referred to as service flows, can be dynamically activated between the base station and the subscriber stations, by using a three-way handshake protocol, called dynamic service addition (DSA). However, the unreliability of the radio medium may require multiple retransmission of DSA messages, leading to a delayed or even unsuccessful activation of a service flow. This paper proposes the novel concept of Quality of Activation (QoA) to guarantee the performance of the DSA protocol. Unlike QoS concept, QoA concept aims at guaranteeing the quality of the DSA message transmissions, rather than that of data transmission. In this paper, QoA is defined in terms of signaling blocking and maximum latency and is achieved by determining a set of constraints that limit the range of DSA protocol parameters. The impact of QoA requirements on protocol parameters is evaluated for various channel quality scenarios and for different types of service flows, i.e., from delay-sensitive service flows to critical and delay-insensitive service flows.

If dynamic bandwidth-guaranteed connections between distributed services (e.g., grid services) are provisioned through a centralized system, the policy to serve connection requests might heavily impact both the success in and the time required for setting up user services (e.g., grid-enabled applications). In this paper, the implementation of a batch queue in the centralized system is proposed. By implementing different service policies for the queued requests, connections and, in consequence, user services can be set up with different guarantees. In this study, a bulk-service policy is proposed and implemented to maximize connection set up success. The experimental evaluation results show that the utilization of the proposed policy brings advantages in terms of percentage of accepted connection requests as the number of requests served in one batch increases. Moreover, the achieved improvement does not impact the time required to set up the connections because of the specific LSP set up procedures implemented in the utilized commercial routers.

Distributed application (e.g., grid-enabled application) performance is highly dependent on the information available when computational resources are chosen. A resource selection based on computational resource information complemented with network performance information has the potential to be optimal from the application performance viewpoint. This is particularly true for network-intensive distributed applications. This study proposes a recursive distributed topology discovery service (RD-TDS) that allows grid clients to retrieve network performance information (i.e., IP-level topology and link capacity) without the need of specific administrative privileges. The RD-TDS exploits a selected set of distributed beacons (i.e., measurement points) that recursively probe newly discovered nodes until no undiscovered nodes are found during an exploration step. The RD-TDS simulative and experimental evaluation confirms its expected qualities: a rapid and complete discovery of the network performance information with the utilization of a limited number of active beacons. In addition, the proposed method rationale can be easily applied to many current network exploration tools.

Within the ITU-T next generation network (NGN) architecture, the resource admission control function (RACF) has been designated to perform the application-driven QoS control across both access and core networks. However, an actual RACF implementation acting on MPLS metro-core networks does not exist since RACF lacks of the capability to configure QoS policies on MPLS network nodes. This prevents an effective end-to-end QoS control in a metro-core scenario on a per-application basis. This work presents a specific implementation of RACF operating over an MPLS network domain. This RACF implementation is applied to a testbed where a video client application requests a real-time video data transfer from a video server through an MPLS network. The admission control is performed upon service request based on video requirements and network resource availability. The differentiated traffic treatment on per-flow basis is realized through setting of MPLS DiffServ-aware traffic engineering (TE) capabilities using the NETCONF protocol. Effective traffic differentiation is achieved in a multi-service network scenario and thus it validates NETCONF as candidate protocol for policy provisioning in MPLS networks.

The simple network management protocol (SNMP) Framework, is one of the most diffused and successful protocol for network management generally available in current network devices.This work studies the dynamic evolution of the SNMP management information based (MIBs) of commercial IP/MPLS routers and evaluates the effectiveness of the relevant implementation. In addition, it characterizes the MIB modules involved in the provisioning of a connectivity and investigates the compliance of MIB implementation as regard the standard specifications. The obtained results were achieved by means of a testbed comprising a software tool developed by the authors. In particular, these results revealed that current MIB implementations do not respect standard specifications in terms of accessibility of the MIB objects. In addition, MIB are often used as a database for storing implementation-specific information, not foreseen by standard specification, rather than to support router operations. Finally, it was found that the configuration of simple connectivity requires the creation and modification of hundreds of different MIB objects thus making the use of SNMP limited to the collection of management information and general notifications.

Future interconnection networks will be required to achieve ultra-high bandwidth and low latency communications to cope with the increasing performance requirements of backbone routers, large data storage systems and supercomputing systems. Aiming at achieving ultra-high bandwidth communications and approaching optical time-of-flight processing latency while being robust to cascade impairments, the authors propose an all-optical packet-switched interconnection network, where not only the actual packet switching but also the packet processing is performed in the photonic domain. The authors present two modular architectures, based on the crossbar and the Batcher–Banyan topologies, capable of forwarding fixed-length packets with two classes of service. Both use photonic digital-processing subsystems built by combining a single integrable module which exploits cross gain modulation in a semiconductor optical amplifier. System level simulations on the crossbar switch controller guarantee that the control signals maintain an acceptable quality during the processing. Moreover, the Batcher–Banyan configuration is more cost-effective than the crossbar for increasing port count, while effective network performance in terms of packet loss rate can be obtained by adding just few recirculating delay lines.

This paper focuses on the problem of ensuring quality of service (QoS) to 4G network users. An adaptive cross-layer (ACL) strategy, that jointly optimizes the parameters of physical (PHY) and medium access control (MAC) layers using queueing theory, is proposed and applied to mobile user communications in an OFDM-based wireless network. PHY and MAC layers are referring to IEEE 802.16 standard, supporting, respectively, different modulations and the automatic repeat request (ARQ) protocol. PHY and MAC layer parameters are here optimally combined by ACL strategy to meet the QoS requirements. The main contribution of the paper is the evaluation of the impact of mobility on ACL strategy performance, by using an accurate channel model that accounts for shadowing effects. The simulation results show that the ACL strategy outperforms non-adaptive or single-layer strategies, in terms of bandwidth savings. Also, ACL strategy is able to guarantee the requested QoS in the different mobility scenarios with different degrees of performance.

Next generation network (NGN) Release 1 is the ITU- T architecture for packet-switched networks that supports the provisioning of broadband and QoS-guaranteed multimedia services, such as Video on Demand and TV streaming, independently of the underlying network transport technologies. Control plane (CP)-enabled transport networks might be a candidate to support NGN services in the Metro/Core segment since are able to setup automatically connections. Typically, these networks are based on automatically switched optical network (ASON) architecture and/or on generalized multiprotocol label switching (GMPLS) protocol suite. This work presents a snapshot of the current status of standardization reached by the NGN architecture and proposes an NGN enhancement to include CP-enable transport networks among the NGN supported transport technologies. An NGN prototype implementing the proposed architectural enhancement is also presented as a proof of concept. The prototype highlights how set-up multimedia over IP (MoIP) services using GMPLS-controlled transport objects.

Wireless and wired networks have commonly evolved separately. However with the integration of quad-play services (i.e., mobile/fixed voice, video, and data) into a single network infrastructure the provisioning of end-to-end connections spanning both the wireless and the wired domains becomes an important issue. In this paper two solutions are proposed for implementing an integrated end-to-end signaling for establishing QoS-guaranteed connections in integrated WiMAX and MPLS based networks. The two solutions are based on the integration of WiMAX management messages and RSVP-TE signaling. Their main difference consists in the way flow WiMAX message and RSVPTE signaling are triggered and coordinated.

Global Grid Computing goal is to connect heterogeneous computational resources belonging to the same Virtual Organization (VO) through the Internet to form a single, more powerful virtual computer. However, to fulfill this goal it is necessary to develop services that provide the virtual computer with the same functionalities of individual end systems, such as security, interprocess communication, and resource management.

The IEEE 802.16 standard for wireless metropolitan area networks allows communications between subscriber stations (SS) through the utilization of the optional Mesh operation mode. In mesh mode, the network base station can centrally schedule transmissions by routing packets on the links of a tree rooted at the BS and covering the mesh network. In this study, strategies for improving the reliability of the message broadcasting from the BS to the SSs are proposed and evaluated. By using the, so called, mesh assisted broadcasting (MAB) strategies, SS may exploit the higher connectivity degree offered by the mesh network during reception and may optionally cooperate with other SSs during the retransmission. MAB strategy performance is evaluated analytically and through simulations. Due to the complexity of the computational problem, analytical models are developed only for the MAB strategies for which the probability that an SS correctly receives a broadcast message can be obtained in closed form. Analytical and simulation results show that MAB strategies may turn the inherent broadcast nature of the radio medium into an increase of broadcasting reliability with respect to the tree-based broadcasting strategy defined in the IEEE 802.16 standard.

In grid computing the need for collecting information about both distributed computational resources and network topology and performance is constantly growing. Several tools are currently under development to provide such information. They are based either on a centralized or a distributed architecture. Distributed tools are commonly based on IP-level application- oriented network metrology. The measurements are done by means of beacons running in some network nodes (e.g., grid hosts) and collecting the required information. However, the number of utilized beacons might heavily impact the final result, i.e. the discovered topology and the collected performance information. In this study a model is developed to estimate the percentage of discovered links provided that a specific number of beacons is placed in the network. The model is developed for Erdos-Renyi (ER) graph network models but it can be applied also to other networks. Numerical evaluation shows that the model closely approximate the percentage of discovered links obtained through simulation for ER networks. For other theoretical and real networks the model overestimates the percentage of discovered links. However experimental results show that for networks with realistic average nodal degree the overestimate is less than 20%.

Applications such as grid computing, storage or video-on-demand may need the provisioning by a transport network of ad-hoc secure end-to-end connections with guaranteed bandwidth, latency and resilience. The service plane (SP) is a functional layer, proposed by the authors, that enhances the automatically switched transport network (ASTN) for the provisioning of network services with a level of abstraction suitable for being invoked by applications. This paper details the distributed signaling running in the SP that implements the SP service abstraction and network resources virtualization capabilities. In particular, it focuses on the design of the signaling architecture among the centralized and distributed entities of the SP for the provisioning of on-demand Layer 3 (L3) virtual private network (VPN). A specific SP implementation is also presented and it is demonstrated by a testbed in which a video client application requests an L3 VPN in order to be connected with a video server across an MPLS-based transport network.

This paper presents the architecture, some specific supporting functions and an experimental validation of a new functional plane, namely the service plane, for realizing an added-value service provisioning (e.g., grid connectivity) for telecommunication operators. First, it is shown as the service plane can be a viable solution for decoupling service and transport development, by masking the transport-related implementation details from the abstract request of a service by a customer or by a qualified application. To this purpose, the service plane exports a high-level interface for supporting application-initiated invocation of QoS-enabled virtual private networks (VPN) or connection-less services. As a significant use case for a grid user, a VPN set-up through the service plane is experimentally demonstrated. Second, some of the main functions that the service plane should support are presented in detail and experimentally assessed, namely a centralized topology discovery service (C-TDS) and path computation service (PCS). As an example, from a grid user perspective, the C-TDS can provide up-to-date information on the grid topology according to various levels of abstraction (physical topology, MPLS topology, and logical topology). Several techniques for the grid topology discovery and various update policies are investigated. PCS elaborates upon the logical topology obtained by TDS and runs linear programming (LP) formulations to identify optimal traffic engineering solutions according to specific objective functions. The combination of C-TDS and PCS represents an an enhanced level of network- awareness in the (network) middleware supporting global grid computing (i.e., grid computing in wide area networks). Experiments performed on IP/MPLS metropolitan network based on commercial routers exhibit a topology delivery performance within a time span in the order of a few seconds and a PCS operation in the order of ten seconds.

Multi-Protocol Label Switching (MPLS) is a connection-oriented paradigm suitable for metro-core networks wherein forwarding decisions in each node are based solely on a short label, much smaller than other packet headers (e.g. IP header). In order to scale and allow for hierarchical traffic aggregation, a Label stacking mechanism has been defined within Multi-Protocol Label Switching (MPLS) protocol. In this paper, label stacking is optimized for static MPLS networks and its impact on the packet processing performance is quantified in real network scenarios. Optimization is carried out by using an integer linear programming formulation and a polynomial time algorithm. Results indicate that the use of label stacking mechanism is recommended in some network scenarios. Moreover, the results evidence that a small size of label stack depth is sufficient to guarantee the performance improvement.

Next generation GMPLS networks will be characterized by domains of transparency, in which the end-to-end optical signal quality has to be guaranteed. Currently GMPLS does not take into account the evaluation of physical impairments. Thus just limited size domains of transparency, where physical impairments can be neglected, are practically achievable. This study utilizes GMPLS signaling protocol extensions to encompass the optical layer physical impairments. The proposed approach allows to detect during the signaling phase whether lightpaths cannot be set up because of unacceptable optical signal quality. In this case successive set up attempts are performed, selecting the alternative routes with three schemes which exploit the feedback information of the signaling messages. Numerical results show that the proposed extensions are able to significantly decrease the lightpath blocking probability due to physical impairments in both static and dynamic conditions.

The control plane (CP) of transport networks consists in a set of entities, communicating through a signaling network, that is responsible for the set-up, release, supervision and maintenance of connections. Given the increased number of capabilities supported by the CP, the management of the CP, i.e. the ability of the management plane (MP) to keep under control the CP operation, is becoming an issue for network operators. Indeed, a proper information model (IM) for the CP is needed to support the management of the CP. In this paper we present a comprehensive proposal of an IM that represents both the CP network itself in terms of components and capabilities and the transport resources as perceived by the management plane (MP) through the CP. The methodology is based on critical review of the standardization efforts already done by ITU-T, TMF, and IETF in order to identify both convergence aspects and gaps that the proposed IM attempts to fill. Specifically, we extend the ITU-T Rec. G.8080 functional components for a CP node, by introducing new objects related to the CP interfaces and control information processing. We then propose a CP functional layering according to the switching capability of the controlled transport network, with the aim of improving the scalability of the CP management. Finally, we define a functional model for the management of routing and connectivity for multi domain scenarios. The contribution is organized in new IM fragments containing a set of managed objects that constitute the abstract representation of the CP network functionalities

In modern communication networks different traffic classes require different quality of service (QoS) guarantees. It is therefore important for the benefit of both communication network users and network providers to meet each traffic class requirement while minimizing the utilized network resources. In this paper the failure-aware idle protection capacity reuse concept, FAIR for short, is presented and evaluated in a network scenario with two connection classes: high and low class lightpaths. High class lightpaths require full reliability against any single failure and are therefore shared path protected. Low class lightpaths might tolerate not be recovered after failure and are therefore unprotected. If low class lightpaths are disrupted by a link failure, they resort to best effort dynamic restoration. The FAIR concept is based on the utilization of idle (i.e., unutilized in the specific failure scenario) high class connection protection resources to recover disrupted low class connections. Numerical results show that the FAIR concept offers a simple yet efficient way to maximize network resource utilization while preserving connection reliability requirements without increasing control protocol overhead. The dynamic restoration of disrupted low class connections on free and idle resources brings a twofold advantage. On one hand it allows to significantly improve low class connection likelihood to be recovered. On the other hand, given a specific low class connection restoration blocking probability threshold, it increases the number of accepted low class connections during the provisioning phase. In addition the dependence of the aforementioned advantages on the network average nodal degree is negligible

In the last few years customers are willing to use broadband connections to support concurrent and heterogeneous services. At the same time telecommunication operators would like to use the same transport infrastructure (possibly with minor changes) to deliver these emerging services in an integrated way. To this purpose, enhancements of the existing ASTN architecture are proposed. Specifically the intelligent network conceptual model is used to introduce an intermediate layer, named service layer, to interface the network customer to a service-independent transport network. The service plane has the task of masking the transport-related implementation details from the abstract request of a service by a customer. In addition, the service layer inherently suggests the separation of the telecommunication operators role in two distinct activities: the network provider and the service provider. The proposed service-oriented architecture is described in terms of functional blocks and interfaces and it consists in an open framework subjects to be implemented using whatever technology, both hardware and software. For a proof of concept, a testbed, named SOON (service oriented optical networks) running the newly developed service-oriented software modules has been implemented as an example of direct interaction between customer and optical network for a dynamic service request. The validation of the architecture is done by demonstrating a working service, namely a virtual private network (VPN) service.

The label stacking mechanism of MPLS is studied in this paper. LSP encapsulation is shown to be able to reduce the MPLS control plane workload, while maintaining the data network blocking probability at acceptable levels.

We address the problem of downlink detection in a mobile radio time division/code division multiple access multirate communication system employing linear modulation. We focus on the detection of a group of intracell codes (ranging from a single one to all the active codes) rejecting both interference coming from the complementary set of undesired intracell codes and co-channel intercell interference. We investigate efficient implementations of linear nonadaptive multiuser detection realized by either joint or separate intersymbol interference and multiple access interference (MAI) mitigation using the zero-forcing or minimum mean square error criteria. The proposed detection schemes employ a tunable-complexity structured description of the MAI for the purpose of detection and interference mitigation. Specifically, the receivers always envision an intracell interference mitigation and data detection capability, while intercell interference is treated differently depending on operating environments. If a statistical description of the intercell interference is available, the receiver realizes group detection in the presence of possibly nonwhite Gaussian noise. Soft hand-over procedures are also proposed wherein direct suppression of intercell interference is possible as well as group detection of the data of the neighboring cells. A unified and finite complexity implementation of the proposed detection schemes based on a sliding window formulation is provided. The numerical results validate the proposed receiver structures showing that a structured description of the observation always leads to a detector with superior performance.

In this paper, we address the problem of the downlink detection in a mobile radio system with hybrid time-division and code-division multiple access, wherein the deployment of orthogonal variable spreading factor codes allows for multirate communication. Accounting for a multipath propagation channel, we focus on the detection of data carried by a group of codes (ranging from a single code, to all active intracell codes) destined to the same mobile station and on the simultaneous rejection of the interference due to the complementary set of active intracell codes. We tackle both the problems of intersymbol interference (ISI) suppression, and multiple access interference (MAI) mitigation, and show when it is convenient to treat these issues together. Specifically, the feasibility of linear detectors based on the zero forcing and the minimum mean square error (MMSE) criterion is investigated, with the aim to mitigate both ISI and MAI. A unified low-complexity formulation based on a sliding window algorithm is proposed for this class of linear detectors. The numerical results validate the proposed receiver structure, indicating that the attainable performance is very close to the single user lower bound up to moderate system loads.

We address maximum likelihood sequence detection (MLSD) for communications on flat Rayleigh fading channels. Making use of linear prediction we derive the structure of an oversampled detector which is computationally efficient and can easily accommodate a time varying Doppler frequency. This goal is achieved through a specific analytical derivation of the prediction coefficients which appear in the metric of the sequence detector. For fractionally-spaced observations, we derive the constraints which allows one to establish an explicit relationship between the set of observation predictors and the set of fading predictors. Then, the equivalence between different classes of prediction-based detectors is shown. The numerical results give useful indications to balance the complexity of these detectors in terms of prediction order, description of intersymbol interference and oversampling.

In per-survivor processing (PSP), the number of parameter estimators equals the number of retained hypothetical data sequences (survivors). The authors propose an algorithm which uses an arbitrary number of parameter estimators and compromises between the two extremes of tentative decisions (one parameter estimator) and PSP. Specific applications to reduced state sequence estimation (RSSE) and maximum likelihood sequence estimation (MLSE) with adaptive tracking of a fading channel are considered.

We propose a fully parametric, time-discrete, symbol-spaced simulation model of frequency-selective mobile radio channels. The model encapsulates transmission and receiver filters and a physical channel accounting for both Rayleigh and Rice fading. The simulator allows one to accurately trade between complexity and quality of representation of the propagation channel, making use of a digital filter of variable order to implement the Doppler spectrum of the fading processes. Numerical results assessing the performance of the model in terms of the simulation time and the power spectrum of the fading processes are provided. A communication system with an adaptive receiver is employed to test the reliability of the propagation model. Increasing the degree of accuracy in the approximation of the Doppler spectrum, the performance of the considered receiver, expressed in terms of symbol error rate, rapidly converges to a specific function of the signal to noise ratio.