Server resource dimensioning and routing of service function chain in NFV network architectures

The Network Function Virtualization (NFV) technology aims at virtualizing the network service with the execution of the single service components in Virtual Machines activated on Commercial-off-the-shelf (COTS) servers. Any service is represented by the Service Function Chain (SFC) that is a set of VNFs to be executed according to a given order. The running of VNFs needs the instantiation of VNF instances (VNFI) that in general are software components executed on Virtual Machines. In this paper we cope with the routing and resource dimensioning problem in NFV architectures. We formulate the optimization problem and due to its NP-hard complexity, heuristics are proposed for both cases of offline and online traffic demand. We show how the heuristics works correctly by guaranteeing a uniform occupancy of the server processing capacity and the network link bandwidth. A consolidation algorithm for the power consumption minimization is also proposed. The application of the consolidation algorithm allows for a high power consumption saving that however is to be paid with an increase in SFC blocking probability

Migration energy aware reconfigurations of virtual network function instances in NFV architectures

Network function virtualization (NFV) is a new network architecture framework that implements network functions in software running on a pool of shared commodity servers. NFV can provide the infrastructure flexibility and agility needed to successfully compete in today's evolving communications landscape. Any service is represented by a service function chain (SFC) that is a set of VNFs to be executed according to a given order. The running of VNFs needs the instantiation of VNF instances (VNFIs) that are software modules executed on virtual machines. This paper deals with the migration problem of the VNFIs needed in the low traffic periods to turn OFF servers and consequently to save energy consumption. Though the consolidation allows for energy saving, it has also negative effects as the quality of service degradation or the energy consumption needed for moving the memories associated to the VNFI to be migrated. We focus on cold migration in which virtual machines are redundant and suspended before performing migration. We propose a migration policy that determines when and where to migrate VNFI in response to changes to SFC request intensity. The objective is to minimize the total energy consumption given by the sum of the consolidation and migration energies. We formulate the energy aware VNFI migration problem and after proving that it is NP-hard, we propose a heuristic based on the Viterbi algorithm able to determine the migration policy with low computational complexity. The results obtained by the proposed heuristic show how the introduced policy allows for a reduction of the migration energy and consequently lower total energy consumption with respect to the traditional policies. The energy saving can be on the order of 40% with respect to a policy in which migration is not performed

Optical communications and networking solutions for the support of C-RAN in a 5G environment

The widespread availability of mobile devices such as tablets and smartphones has led to fast-increasing mobile data traffic in the last few years [...

Military rhetoric between protreptic tradition and strategic thought

“La Retórica militar, el logikon meros” del compendio del maestro Syriano, es un único y original tratado del género protretico. Mientras los primeros indicios de este género se pueden ver en La Ilíada de Homero, las historias de Tucídides son el ejemplo no superado de la literatura militar posterior, particularmente de Procopius. La estructura de la retórica militar organizada en la teoría atribuida a Hermógenes de Tarso, combina los términos protrepticos con pensamientos estratégicos, que denotan madurez en época bizantina. De acuerdo a esta teoría, en términos de guerra los temas de relaciones y emociones, son más importantes que las batallas con armas.“Rhetorica militaris, the logikon meros” of Syrianus Magister’s compendium, is an original, unique stage of the history of the protreptic genre. While the first signs of the genre can be seen already in Homer’s “Iliad,” Thucydides’ Histories are in this field an unsurpassed example for later military historians, and particularly for Procopius. The rhetorical structure of the “Rhetorica militaris,” organized upon the theories attributed to Hermogenes of Tarsus, combines protreptic themes with strategic thought, which in the Byzantine age assumes a mature character. According to this theory, in times of war relational and emotional issues can be more important than battles with weapons.La “Rhetorica militaris, il logikon meros” del compendio di Siriano Magister, si pone come tappa tanto originale quanto isolata del processo evolutivo del genere protrettico. Se i prodromi sono ravvisabili già nell’”Iliade” omerica, le Storie tucididee rappresentano anche per tale ambito un esempio insuperato per gli storici militari di età successive, tra questi soprattutto Procopio. L’opuscolo, il cui impianto è esemplato sulle teorie esposte nel corpus attribuito ad Ermogene di Tarso, coniuga i motivi protrettici con una riflessione strategica che nell’età bizantina assume una fisionomia matura: in guerra le istanze relazionali ed emozionali possono essere più importanti dello scontro in armi

Petrochemical outlook still bleak for 2002

Petroleum industry and trade

Chapter Sul rapporto semantico tra dati grafici e numerici in un modello di valutazione del Rischio archeologico

The 43rd UID conference, held in Genova, takes up the theme of ‘Dialogues’ as practice and debate on many fundamental topics in our social life, especially in these complex and not yet resolved times. The city of Genova offers the opportunity to ponder on the value of comparison and on the possibilities for the community, naturally focused on the aspects that concern us, as professors, researchers, disseminators of knowledge, or on all the possibile meanings of the discipline of representation and its dialogue with ‘others’, which we have broadly catalogued in three macro areas: History, Semiotics, Science / Technology. Therefore, “dialogue” as a profitable exchange based on a common language, without which it is impossible to comprehend and understand one another; and the graphic sign that connotes the conference is the precise transcription of this concept: the title ‘translated’ into signs, derived from the visual alphabet designed for the visual identity of the UID since 2017. There are many topics which refer to three macro sessions: - Witnessing (signs and history) - Communicating (signs and semiotics) - Experimenting (signs and sciences) Thanks to the different points of view, an exceptional resource of our disciplinary area, we want to try to outline the prevailing theoretical-operational synergies, the collaborative lines of an instrumental nature, the recent updates of the repertoires of images that attest and nourish the relations among representation, history, semiotics, sciences

Disentangling demand and supply in credit developments: a survey-based analysis for Italy

This paper combines qualitative information from the Eurosystem Bank Lending Survey with micro-data on loan prices and quantities for the participating Italian banks to assess the role of supply and demand factors in credit developments, with a focus on the sharp slowdown of 2008-09. Both demand and supply have played a relevant role, especially for lending to enterprises, in the whole sample period and during the financial crisis. A counterfactual exercise shows that the effect of supply factors on the growth of lending to firms was strongest after the Lehman collapse. On average, over the crisis period (2007q3-2009q4) the negative effect on the annualized quarter-on-quarter growth rate of the panel banksÂ’ lending to enterprises can be estimated in a range of 2.2 to 3.1 percentage points, depending on the specification. About one fourth of the total supply effect can be attributed to costs related to the banksÂ’ balance sheet position, the rest to their perception of credit risk.credit growth, supply tightening, financial crisis