Traffic Management Applications for Stateful SDN Data Plane

The successful OpenFlow approach to Software Defined Networking (SDN) allows network programmability through a central controller able to orchestrate a set of dumb switches. However, the simple match/action abstraction of OpenFlow switches constrains the evolution of the forwarding rules to be fully managed by the controller. This can be particularly limiting for a number of applications that are affected by the delay of the slow control path, like traffic management applications. Some recent proposals are pushing toward an evolution of the OpenFlow abstraction to enable the evolution of forwarding policies directly in the data plane based on state machines and local events. In this paper, we present two traffic management applications that exploit a stateful data plane and their prototype implementation based on OpenState, an OpenFlow evolution that we recently proposed.Comment: 6 pages, 9 figure

A "poor man's" approach for high-resolution three-dimensional topology optimization of natural convection problems

This paper treats topology optimization of natural convection problems. A simplified model is suggested to describe the flow of an incompressible fluid in steady state conditions, similar to Darcy's law for fluid flow in porous media. The equations for the fluid flow are coupled to the thermal convection-diffusion equation through the Boussinesq approximation. The coupled non-linear system of equations is discretized with stabilized finite elements and solved in a parallel framework that allows for the optimization of high resolution three-dimensional problems. A density-based topology optimization approach is used, where a two-material interpolation scheme is applied to both the permeability and conductivity of the distributed material. Due to the simplified model, the proposed methodology allows for a significant reduction of the computational effort required in the optimization. At the same time, it is significantly more accurate than even simpler models that rely on convection boundary conditions based on Newton's law of cooling. The methodology discussed herein is applied to the optimization-based design of three-dimensional heat sinks. The final designs are formally compared with results of previous work obtained from solving the full set of Navier-Stokes equations. The results are compared in terms of performance of the optimized designs and computational cost. The computational time is shown to be decreased to around 5-20% in terms of core-hours, allowing for the possibility of generating an optimized design during the workday on a small computational cluster and overnight on a high-end desktop

New Observations on the Imperial Reliefs from the Sebasteion at Aphrodisias and the Portraiture of Claudius, Britannicus, and the Young Nero

This article reconsiders the identification of several imperial personages and personifications from the Julio-Claudian Sebasteion at Aphrodisias. Certain of these reliefs also offer insight into the likely reason for the creation of one of Claudius’ portrait types that influenced the hairstyles of his natural son Britannicus and his adopted son Nero. Reevaluated too are portraits in-the-round that have long been attributed to the young Nero but which I show represent instead Britannicus. Even though the epigraphic record proves that many portraits of Britannicus were set up, there has been no agreement about the identification of any of his images. My new observations establish his portrait type, based on numismatic evidence and especially on two little-known sculptural portraits representing him as a child wearing the corona civica. The establishment of Britannicus’ portraiture and revision of the portrait type of the young Nero also lead to new conclusions about the Sebasteion’s problematic ›Two Princes‹ relief

Intersectional design in practice a critical perspective on sustainability for all

GreenSCENT - Smart Citizens Education for a Green Futur

zCap: a zero configuration adaptive paging and mobility management mechanism

Today, cellular networks rely on fixed collections of cells (tracking areas) for user equipment localisation. Locating users within these areas involves broadcast search (paging), which consumes radio bandwidth but reduces the user equipment signalling required for mobility management. Tracking areas are today manually configured, hard to adapt to local mobility and influence the load on several key resources in the network. We propose a decentralised and self-adaptive approach to mobility management based on a probabilistic model of local mobility. By estimating the parameters of this model from observations of user mobility collected online, we obtain a dynamic model from which we construct local neighbourhoods of cells where we are most likely to locate user equipment. We propose to replace the static tracking areas of current systems with neighbourhoods local to each cell. The model is also used to derive a multi-phase paging scheme, where the division of neighbourhood cells into consecutive phases balances response times and paging cost. The complete mechanism requires no manual tracking area configuration and performs localisation efficiently in terms of signalling and response times. Detailed simulations show that significant potential gains in localisation effi- ciency are possible while eliminating manual configuration of mobility management parameters. Variants of the proposal can be implemented within current (LTE) standards

SPIDER: Fault Resilient SDN Pipeline with Recovery Delay Guarantees

When dealing with node or link failures in Software Defined Networking (SDN), the network capability to establish an alternative path depends on controller reachability and on the round trip times (RTTs) between controller and involved switches. Moreover, current SDN data plane abstractions for failure detection (e.g. OpenFlow "Fast-failover") do not allow programmers to tweak switches' detection mechanism, thus leaving SDN operators still relying on proprietary management interfaces (when available) to achieve guaranteed detection and recovery delays. We propose SPIDER, an OpenFlow-like pipeline design that provides i) a detection mechanism based on switches' periodic link probing and ii) fast reroute of traffic flows even in case of distant failures, regardless of controller availability. SPIDER can be implemented using stateful data plane abstractions such as OpenState or Open vSwitch, and it offers guaranteed short (i.e. ms) failure detection and recovery delays, with a configurable trade off between overhead and failover responsiveness. We present here the SPIDER pipeline design, behavioral model, and analysis on flow tables' memory impact. We also implemented and experimentally validated SPIDER using OpenState (an OpenFlow 1.3 extension for stateful packet processing), showing numerical results on its performance in terms of recovery latency and packet losses.Comment: 8 page

Evaluation of Airport Security Training Programs: Perspectives and Issues

While many governments and airport operators have emphasized the importance of security training and committed a large amount of budget to security training programs, the implementation of security training programs was not proactive but reactive. Moreover, most of the security training programs were employed as a demand or a trendchasing activity from the government. In order to identify issues in airport security training and to develop desirable security training procedures in an airport, this preliminary study aims at providing (1) the description of current state of airport security training and training in general, (2) the study design and interview guide for studying airport security training, and (3) expected outcome from the study

A Dream Picture

https://digitalcommons.library.umaine.edu/mmb-ps/2989/thumbnail.jp

Carpomya vesuviana A. Costa (Diptera Tephritidae Trypetinae Carpomyini) from jujube tree in Emilia-Romagna (Northern Italy)

The presence of Carpomya vesuviana (Diptera Tephritidae) on fruit of jujube tree (Ziziphus jujuba) in Emilia- Romagna (Northern Italy) is reported. Some aspects of the biology of the species are described. Differently from southern regions, where C. vesuviana is polivoltine, in Emilia-Romagna only one generation per year occurs.