Openflow switching: data plane performance

Abstract—OpenFlow is an open standard that can be implemented in Ethernet switches, routers and wireless access points (AP). In the OpenFlow framework, packet forwarding (data plane) and routing decisions (control plane) run on different devices. OpenFlow switches are in charge of packet forwarding, whereas a controller sets up switch forwarding tables on a perflow basis, to enable flow isolation and resource slicing. We focus on the data path and analyze the OpenFlow implementation in Linux based PCs. We compare OpenFlow switching, layer-2 Ethernet switching and layer-3 IP routing performance. Forwarding throughput and packet latency in underloaded and overloaded conditions are analyzed, with different traffic patterns. System scalability is analyzed using different forwarding table size, and fairness in resource distribution is measured. I

Energy saving in distributed router architectures

A multi-stage software router overcomes scalability issues related to a single, PC-based, software router by introducing parallel forwarding paths. However, since the architecture includes different internal components, energy inefficiency at low loads may arise if the multi-stage internal architecture does not adapt to currently offered traffic. This paper presents an energy-saving scheme to improve energy efficiency of the multi-stage router architecture by focusing on the back-end stage and sizing it to the offered load to reduce energy needs. The problem is defined as a mixed integer linear programming model, shown to be NP-hard. We tackle the scalability issues of the optimal problem by defining a twostep heuristic which takes advantage of existing BIN PACKING algorithms. Our results shows that the two-step solution is within 10% relative error with respect to the optimal solution for different realistic scenario

Differential energy saving algorithms in a distributed router architecture

A distributed multistage software router (MSSR) is composed by several interconnected software routers running on personal computers (PCs). The MSSR architecture overcomes scalability and performance issues of single software router by providing parallel forwarding paths. Like many networking devices, a MSSR must be sized for peak traffic load, which implies energy inefficiency at low loads. Thus, we focus on energy saving schemes to improve the router energy efficiency by dynamically adapting the MSSR architecture to the currently offered load. We first introduce an optimal energy saving algorithm defined as a mixed integer linear programming (MILP) optimization model. Then, heuristic solutions, named differential algorithms are discussed. While the optimal approach provides higher energy savings, the heuristics avoid the complete MSSR reconfiguration, thus reducing forwarding delays and minimizing service interruption. The performance evaluation shows that the proposed heuristic algorithms, that gracefully modifies the internal MSSR configuration, preserve the load proportional energy demand characteristics of the optimal algorithm, with a minimal loss of efficiency, largely compensated by algorithm simplicity

A Supervisory Control Strategy for Improving Energy Efficiency of Artificial Lighting Systems in Greenhouses

Artificial lighting systems are used in commercial greenhouses to ensure year-round yields. Current Light Emitting Diode (LED) technologies improved the system efficiency. Nevertheless, having artificial lighting systems extended for hectares with power densities over 50W/m2 causes energy and power demand of greenhouses to be really significant. The present paper introduces an innovative supervisory and predictive control strategy to optimize the energy performance of the artificial lights of greenhouses. The controller has been implemented in a multi-span plastic greenhouse located in North Italy. The proposed control strategy has been tested on a greenhouse of 1 hectare with a lighting system with a nominal power density of 50 Wm−2 requiring an overall power supply of 1 MW for a period of 80 days. The results have been compared with the data coming from another greenhouse of 1 hectare in the same conditions implementing a state-of-the-art strategy for artificial lighting control. Results outlines that potential 19.4% cost savings are achievable. Moreover, the algorithm can be used to transform the greenhouse in a viable source of energy flexibility for grid reliability

OpenFlow driven ethernet traffic analysis

Software Defined Networking (SDN) is a new networking paradigm that permits to slice network infrastructures. An example of SDN is the OpenFlow framework, where the control plane runs on a separate device, called controller, that manages data forwarding switches. The OpenFlow protocol ensures communications between OpenFlow switches and the OpenFlow controller. Before widely deploying OpenFlow based networks, scalability and performance of such networks should be studied and better understood. In this paper, the scalability of NOX, one of the most popular OpenFlow controller, is analyzed through both simulation and lab measurements. We perform an Ethernet trace analysis on the controller by defining flow characteristics as would be seen by an OpenFlow controller. We study the potential trace impact on an OpenFlow controller, analyzing among others, the number of flows, flow inter arrival times, traffic volumes and flow size distribution. Our results permit to discuss the feasibility of running OpenFlow networks with a single commodity PC as the controller in a mid-size campus network

Chemometric Differentiation of Sole and Plaice Fish Fillets Using Three Near-Infrared Instruments

Fish species substitution is one of the most common forms of fraud all over the world, as fish identification can be very challenging for both consumers and experienced inspectors in the case of fish sold as fillets. The difficulties in distinguishing among different species may generate a “grey area” in which mislabelling can occur. Thus, the development of fast and reliable tools able to detect such frauds in the field is of crucial importance. In this study, we focused on the distinction between two flatfish species largely available on the market, namely the Guinean sole (Synaptura cadenati) and European plaice (Pleuronectes platessa), which are very similar looking. Fifty fillets of each species were analysed using three near-infrared (NIR) instruments: the handheld SCiO (Consumer Physics), the portable MicroNIR (VIAVI), and the benchtop MPA (Bruker). PLS-DA classification models were built using the spectral datasets, and all three instruments provided very good results, showing high accuracy: 94.1% for the SCiO and MicroNIR portable instruments, and 90.1% for the MPA benchtop spectrometer. The good classification results of the approach combining NIR spectroscopy, and simple chemometric classification methods suggest great applicability directly in the context of real-world marketplaces, as well as in official control plans