Megalos: A Scalable Architecture for the Virtualization of Network Scenarios

We introduce an ETSI NFV compliant, scalable, and distributed architecture, called Megalos, that supports the implementation of virtual network scenarios consisting of virtual devices (VNFs) where each VNF may have several L2 interfaces assigned to virtual LANs. We rely on Docker containers to realize VNFs and we leverage Kubernetes for the management of the nodes of a distributed cluster. Our architecture guarantees the segregation of each virtual LAN traffic from the traffic of other LANs, from the cluster traffic, and from Internet traffic. Also, a packet is only sent to the cluster node containing the recipient VNF. The allocation of the VNFs to the nodes of the cluster is performed by Megalos Scheduler, taking into account the network topology in order to reduce the traffic among nodes. We produce an example application where we emulate a large network scenario, with thousands of VNFs and LANs, on a small cluster of 50 nodes. Finally, we experimentally show the scalability potential of Megalos by measuring the overhead of the distributed environment and of its signaling protocols

Megalos: A scalable architecture for the virtualization of large network scenarios

We introduce an open-source, scalable, and distributed architecture, called Megalos, that supports the implementation of virtual network scenarios consisting of virtual devices (VDs) where each VD may have several Layer 2 interfaces assigned to virtual LANs. We rely on Docker containers to realize vendor-independent VDs and we leverage Kubernetes for the management of the nodes of a distributed cluster. Our architecture does not require platform-specific configurations and supports a seamless interconnection between the virtual environment and the physical one. Also, it guarantees the segregation of each virtual LAN traffic from the traffic of other LANs, from the cluster traffic, and from Internet traffic. Further, a packet is only sent to the cluster node containing the recipient VD. We produce several example applications where we emulate large network scenarios, with thousands of VDs and LANs. Finally, we experimentally show the scalability potential of Megalos by measuring the overhead of the distributed environment and of its signaling protocols

Sibyl: A Framework for Evaluating the Implementation of Routing Protocols in Fat-Trees

Several data centers adopt fat-tree topologies, where high bisection bandwidth is achieved by interconnecting commodity hardware and by using specific routing solutions. These solutions, which include protocol implementations and configurations, are difficult to evaluate and test both for the density of fat-trees and for the complexity of the protocols. Also, since most issues show up only when a fault happens, it is unfeasible to perform such tests in a production environment. Additionally, the lack of standard testing procedures motivates an effort in developing solutions for such a critical task. In this paper, we propose a methodology devised for testing fat-tree routing protocol implementations. It adopts a wall-clock independent method to establish metrics, which permits normalizing the results of different routing protocol implementations independently from the execution environment. The methodology is implemented by Sibyl, a software framework developed to perform repeatable tests on arbitrary fat-tree topologies automatically. Sibyl also provides a set of tools to analyze the results and investigate implementation behaviors. We evaluate the methodology and Sibyl in three use cases. Such use cases witness a wide spectrum of situations where Sibyl is effective for analyzing, comparing, developing, and debugging routing protocol implementations

Low-dose modified-release prednisone in axial spondyloarthritis: 3-month efficacy and tolerability

Francesca Bandinelli,1 Francesco Scazzariello,1 Emanuela Pimenta da Fonseca,2 Mittermayer Barreto Santiago,2 Claudio Marcassa,3 Francesca Nacci,1 Marco Matucci Cerinic1 1Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy; 2Service of Rheumatology, Hospital Santa Isabel, Escola de Medicina e Saúde Pública, Bahia, Brazil; 3Maugeri Clinical and Scientific Institutes, IRCCS, Veruno, Novara, Italy Background: Oral glucocorticoids (GCs) have been shown to be effective in reducing the inflammatory symptoms of rheumatoid arthritis, but their use is not supported by evidence in spondyloarthritis (SpA). Modified-release (MR) oral prednisone taken at bedtime has been shown to be more effective than immediate-release prednisone taken in the morning. The efficacy of low-dose MR prednisolone in patients with SpA is unknown. Patients and methods: This single-center cohort study retrospectively assessed the effectiveness and safety of 12-week low-dose MR prednisone (5 mg daily, bedtime administration) in GC-naïve adult patients with symptomatic axial SpA. A 50% improvement of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) or a final BASDAI score of <4 according to disease activity at baseline was chosen as the primary outcome parameter after MR prednisone. Results: Fifty-seven patients were evaluated; of them, 41 had an active disease (BASDAI score of ≥4) at baseline. MR prednisone significantly reduced BASDAI (from 5.5±2.6 to 3.0±2.8, P<0.001) as well as inflammatory symptoms, pain, fatigue and morning stiffness. The overall response rate after MR prednisone was 52.6% (53.7% in patients with active SpA and 50.0% in patients with low-active disease; nonsignificant). At multivariable analysis, none of the considered clinical findings independently predicted the response to MR prednisone in subjects with active SpA. Overall, seven patients (11.8%) had nonserious adverse drug reactions after MR prednisone. Conclusion: In patients with symptomatic SpA and naïve to GCs, low-dose MR prednisone reduced the symptoms and clinical indexes of disease activity and showed a positive safety profile. Keywords: spondyloarthritis, morning stiffness, glucocorticoids, modified-release prednison

Use of traffic crash as a risk assessment scale in hospitalized seniors: A perspective observational study

Background and aim: According to the World Health Organization (WHO), falls represent the second main cause of accidental and involuntary deaths worldwide, which led to define them as one of the “four giants of the geriatrician” that particularly affect the elderly aged ≥ 65 years. The study’s aim is to evaluate whether the Traffic Crash scale is valid in identifying patients at risk of falling by comparing it to the Conley scale currently used. Methods: Prospective observational study evaluating the fall risk using TC on a sample of patients aged ≥ 65 years, hospitalized in General Medicine Ward and Gastroenterology, after informed consent and favorable opinion of the AVEN Ethics Committee. The results are compared with those obtained from the Conley scale, and with those obtained from the indications of the Business Operating Instruction. The method of administration occurred concurrently and distinctly on the same patient by two researchers in order to demonstrate the scale inter-rater reliability. Results: The final sample was made up of 88 patients. Data shows that 46 out of 55 patients (84%) are medium / high risk for both scales. According to the indications of the Company Operating Instruction, the entire sample is at risk. The inter-rater reliability was confirmed with Cohen’s K which is equal to p = 1. Conclusions: The TC scale is comparable to Conley scale, for the fall risk identification but specifically the stratification is low-medium-high. Therefore, in future, this will make it possible to implement personalized prevention interventions in care planning. (www.actabiomedica.it)