Giorgio Nunzi

Distributed autonomic resource management for network virtualization

Network virtualization is an emerging trend claimed to reduce the costs of future networks. The key strategy in network virtualization is of slicing physical resources (links, routers, servers, etc.) to create virtual networks composed of subsets of these slices. One important challenge on network virtualization is the resource management of the physical or substrate networks. Sophisticated management techniques should be used to accomplish such management. The sophisticated techniques offered by autonomic communications rise as an appropriated alternative to address the challenges of managing the efficient use of substrate resources on network virtualization. Thus, this paper proposes a distributed self-organizing model to manage the substrate network resources. An evaluation scenario is depicted and simulations show that approximately 36.8% of the network traffic load can be spared when the self-organizing model is enabled in the evaluated scenario.

Probabilistic decentralized network management

This work proposes a probabilistic management paradigm for solving some major challenges of decentralized network management. Specifically, we show how to cope with 1) the overhead of redundant information gathering and processing, 2) the decentralized management in dynamic and unpredictable environments, and 3) the considerable effort required for decentralized coordination of management functions. To this end, we describe a framework for probabilistic decentralized management in the context of In-Network Management (INM). We demonstrate how this framework can be applied to a network of information, a novel clean-slate approach towards an information-centric future Internet. We show by means of a simulation study in the area of performance and fault management that we can significantly reduce the effort and resources dedicated to management, while we are able to achieve a sound level of accuracy of the overall network view.

Distributed Self-Optimization of Handover for the Long Term Evolution

The 3GPP Long Term Evolution (LTE) is defining the next generation radio access network which introduces advanced service capabilities in base stations. Consequently, self-management is seen as an enabling technique for the deployment of LTE. This paper discusses handover optimization options for base stations and evaluates one possible approach of distributed self-optimization. After a review of the key aspects related to handover optimization, a self-optimization technique for handover based on trial-and-error is presented. The interference between neighboring nodes, a typical problem of distributed systems, is analyzed in more detail and a technique to cope with it is presented. Simulation results show that the control algorithm can achieve the expected optimal configuration through iterative steps and the effect of interfering neighboring nodes can be mitigated at the expense of a longer optimization time.

Architectural principles and elements of in-network management

Recent endeavors in addressing the challenges of the current and future Internet pursue a clean slate design methodology. Simultaneously, it is argued that the Internet is unlikely to be changed in one fell swoop and that its next generation requires an evolutionary design approach. Recognizing both positions, we claim that cleanness and evolution are not mutually exclusive, but rather complementary and indispensable properties for sustainable management in the future Internet. In this paper we propose the in-network management (INM) paradigm, which adopts a clean slate design approach to the management of future communication networks that is brought about by evolutionary design principles. The proposed paradigm builds on embedded management capabilities to address the intrinsic nature, and hence, close relationship between the network and its management. At the same time, INM assists in the gradual adoption of embedded self-managing processes to progressively achieve adequate and practical degrees of INM. We demonstrate how INM can be exploited in current and future network management by its application to P2P networks.

Distributed Reallocation Scheme for Virtual Network Resources

Network virtualization is an emerging technology for cost-effective sharing of network resources. The key strategy in network virtualization is of slicing physical resources (links, CPU, memory, and storage) to create virtual networks that are assigned to different operators. One important challenge on network virtualization is the efficient use of the physical resources. To accomplish such efficient use the management of the physical resources should be transparent to the applications running within the virtual networks, and should be executed at runtime in order to deal with the variation on the load requests of different virtual networks. Traditional resource allocation schemes use offline, centralized, and global view strategies to manage the use of physical resources. In contrast to these strategies, we propose a runtime, distributed, local view approach to manage physical resources. In this paper we introduce a virtual network architecture and an associated self-organizing algorithm to reallocate virtual network resources along different physical nodes in order to equalize the bandwidth, and storage consumption on the physical nodes. We developed a virtual network model based on Omnet++ to simulate the designed self-organizing algorithm. An IPTV testbed scenario is presented and initial experiments, about the interruption time of the application inside the IPTV virtual network, are described.

A Framework for In-Network Management in Heterogeneous Future Communication Networks

Future communication networks will be composed of a diversity of highly heterogeneous network variants, ranging from energy constrained wireless sensor networks to large-scale wide area networks. The fact that the size and complexity of such networks will experience tremendous growth will eventually render existing traditional network management paradigms unfeasible. We propose the radically new paradigm of in-network management,which targets the embedding of self-management capabilities deep inside the network nodes. In this paper, we focus on our framework for in-network management,which allows management logic to be embedded and executed within network nodes. Based on a specific use-case of bio-inspired network management, we demonstrate how our framework can be exploited in a network failure scenario using quorum sensing and chemotaxis.

User-assisted coverage and interference optimization for broadband femtocells

We present ways for user-assisted coverage configuration and interference optimization. The femtocell coverage is measured in a user-assisted site survey, followed by an automatized evaluation and femtocell configuration adjustment. To achieve this, the user only needs his mobile phone for interaction. Existing, commercial technology only offers measurement of the radio environment and a visualization of the respective results. We describe how measurements of at least two measurement series at different power levels along an identical path can be used to find a good configuration in an automatized manner. It is described how measurement sequences can be aligned to make them comparable to each other.

Event handling in clean-slate Future Internet management

Event handling is a management mechanism that provides means for the network to react on changes in the network conditions or performance. In the construction of a clean-slate management architecture, we consider this as a main building block. This paper proposes a fully distributed event distribution in a fully distributed environment: differently from existing works, no configuration is required in advance, and yet nodes have guarantee that events are delivered and that certain delivery objectives are respected. The contributions of this paper are: a generic system model for event handling and an analysis of event distribution mechanisms with respect to timeliness and traffic metrics. The paper describes and discusses in detail the results based on simulations and provides guidelines for management functions of the Future Internet.

Fast RTP Retransmission for IPTV - Implementation and Evaluation

With the deployment of IPTV reliability for multicast is becoming an important research topic again. Even though it has been intensively investigated before, there is now an understanding of the deployment scenario and the application requirements that allows solutions to be evaluated in detail. We describe how to design a fast retransmission cache based on recent extensions of RTP. We have implemented a prototype intended for deployment in an access node and explain the necessary trade-offs in the design. The paper also contains a performance evaluation which shows the efficiency of the retransmission functionality to handle losses and its performance in congested networks.

Maintenance of Monitoring Systems Throughout Self-healing Mechanisms

Monitoring is essential in modern network management. However, current monitoring systems are unable to recover their internal faulty entities forcing the network administrator to manually fix the occasionally broken monitoring solution. In this paper we address this issue by introducing a self-healing monitoring solution. This solution is described considering a scenario of a monitoring system for a Network Access Control (NAC) installation. The proposed solution combines the availability provided by P2P-based overlays with self-healing abilities. This paper also describes a set of experimental evaluations whose results present the tradeoff between the time required to recover the monitoring infrastructure when failures occur, and the associated bandwidth consumed in this process. Based on the experiments we show that it is possible to improve availability and robustness with minimum human intervention.