Design and implementation of the OFELIA FP7 facility: The European OpenFlow testbed

The growth of the Internet in terms of number of devices, the number of networks associated to each device and the mobility of devices and users makes the operation and management of the Internet network infrastructure a very complex challenge. In order to address this challenge, innovative solutions and ideas must be tested and evaluated in real network environments and not only based on simulations or laboratory setups. OFELIA is an European FP7 project and its main objective is to address the aforementioned challenge by building and operating a multi-layer, multi-technology and geographically distributed Future Internet testbed facility, where the network itself is precisely controlled and programmed by the experimenter using the emerging OpenFlow technology. This paper reports on the work done during the first half of the project, the lessons learned as well as the key advantages of the OFELIA facility for developing and testing new networking ideas. An overview on the challenges that have been faced on the design and implementation of the testbed facility is described, including the OFELIA Control Framework testbed management software. In addition, early operational experience of the facility since it was opened to the general public, providing five different testbeds or islands, is described

Does inter-vertebral range of motion increase after spinal manipulation? A prospective cohort study.

Background: Spinal manipulation for nonspecific neck pain is thought to work in part by improving inter-vertebral range of motion (IV-RoM), but it is difficult to measure this or determine whether it is related to clinical outcomes. Objectives: This study undertook to determine whether cervical spine flexion and extension IV-RoM increases after a course of spinal manipulation, to explore relationships between any IV-RoM increases and clinical outcomes and to compare palpation with objective measurement in the detection of hypo-mobile segments. Method: Thirty patients with nonspecific neck pain and 30 healthy controls matched for age and gender received quantitative fluoroscopy (QF) screenings to measure flexion and extension IV-RoM (C1-C6) at baseline and 4-week follow-up between September 2012-13. Patients received up to 12 neck manipulations and completed NRS, NDI and Euroqol 5D-5L at baseline, plus PGIC and satisfaction questionnaires at follow-up. IV-RoM accuracy, repeatability and hypo-mobility cut-offs were determined. Minimal detectable changes (MDC) over 4 weeks were calculated from controls. Patients and control IV-RoMs were compared at baseline as well as changes in patients over 4 weeks. Correlations between outcomes and the number of manipulations received and the agreement (Kappa) between palpated and QF-detected of hypo-mobile segments were calculated. Results: QF had high accuracy (worst RMS error 0.5o) and repeatability (highest SEM 1.1o, lowest ICC 0.90) for IV-RoM measurement. Hypo-mobility cut offs ranged from 0.8o to 3.5o. No outcome was significantly correlated with increased IV-RoM above MDC and there was no significant difference between the number of hypo-mobile segments in patients and controls at baseline or significant increases in IV-RoMs in patients. However, there was a modest and significant correlation between the number of manipulations received and the number of levels and directions whose IV-RoM increased beyond MDC (Rho=0.39, p=0.043). There was also no agreement between palpation and QF in identifying hypo-mobile segments (Kappa 0.04-0.06). Conclusions: This study found no differences in cervical sagittal IV-RoM between patients with non-specific neck pain and matched controls. There was a modest dose-response relationship between the number of manipulations given and number of levels increasing IV-RoM - providing evidence that neck manipulation has a mechanical effect at segmental levels. However, patient-reported outcomes were not related to this

Partial offloading of OpenFlow rules on a traditional hardware switch ASIC

OpenFlow represents a new powerful paradigm that combines the flexibility of the software with the efficiency of a programmable hardware switch. However, such an approach is currently reserved for new hardware devices, specifically engineered for this paradigm. This paper presents our experience and findings about selectively offloading OpenFlow rules into a non-OpenFlow compatible hardware switch silicon, which enables existing (legacy) hardware ASICs to become compatible with the SDN paradigm. We describe our solution that transparently offloads the portion of OpenFlow rules supported by the hardware while keeping in software the remaining ones, and that is able to support the presence of multiple hardware tables although with limited capabilities in terms of matches and actions. Moreover, we illustrate the design choices used to implement all the basic functionalities required by the OpenFlow protocol (e.g., packet-in, packet-out messages) and then we demonstrate the considerable advantage in terms of performance that can be obtained by performing switching in hardware, while maintaining an SDN-type ability to program and to instantiate desired network operations from a central controlle

SplitArchitecture: SDN for the carrier domain

The concept of SDN has emerged as a way to address numerous challenges with traditional network architectures by decoupling network control and forwarding. So far, the use cases for SDN mainly targeted data-center applications. This article considers SDN for network carriers, facing operation of large-scale networks with millions of customers, multiple technologies, and high availability demands. With specific carrier-grade features such as scalability, reliability, flexibility, modularity, and virtualization in mind, the SPARC EU project has developed the SPARC SplitArchitecture concept. The SplitArchitecture control plane allows hierarchical layering of several control plane layers which can be flexibly mapped to data plane layers. Between control layers open interfaces are used. Furthermore, SplitArchitecture proposes an additional split of forwarding and processing functions in data path elements, enabling switch based OAM functionality and handling of tunneling techniques. The SplitArchitecture concept is evaluated in a prototype demonstrating an SDN version of BRAS: the floating BRAS. The floating BRAS allows creation of residential Internet access services with dynamically managed BRAS instances. The demo is based on a controller enabling protected MPLS transport connections spanning SDN-controlled aggregation and IP/MPLS-based core domains. The prototype showcases how SplitArchitecture enables virtualization of service nodes in an SDN-controlled network, leading to increased flexibility in configuration and placement of service creation functions. Overall, the results show that it is technically and economically beneficial to apply SDN, and specifically the SplitArchitecture concept, to the carrier domain

A datapath-centric virtualization mechanism for OpenFlow networks

Abstract: The adoption of a robust and scalable network virtualization framework is a key requirement in order to make the vision of a shareable network infrastructure a reality. To this aim, one of the most suitable approaches is the one which takes advantage of the emerging paradigm of Software-Defined Networking (SDN) and OpenFlow, its de-facto standard. Several virtualization frameworks have been proposed in the last few years, however, they are either based on proxy-based solutions that raises scalability and robustness issues (FlowVisor), or they rely on a simplified view of the data path (generally based on Open vSwitch instances) that have little chances to be adopted in production network settings. This paper presents a novel OpenFlow-based network virtualization mechanism exploiting a recent open-source data path project named extensible Data path Daemon (xDPd), the proposed multi-platform data path is based on a robust distributed virtualization architecture that is able to run on multi-version OpenFlow switch network scenarios, has a minimal overhead from a performance point of view and can be easily ported on several hardware platforms via xDPd libraries

User-specific Network Service Functions in an SDN-enabled Network Node

Network Functions Virtualization can enable each user (tenant) to define his desired set of network services, called (network) service graph. For instance, a User1 may want his traffic to traverse a firewall before reaching his terminal, while a User2 may be interested in a different type of firewall and in a network monitor as well. This paper presents a prototype of an SDN-enabled node that, given a new user connected to one of its physical ports, it is able to dynamically instantiate the user’s network service graph and force all his traffic to traverse the proper set of network functions

CREATE-NET's Real-life service-oriented testbed in trento

CREATE-NET's testbed is an open, service-oriented environment, implemented on a real-life city-wide communication infrastructure deployed in the city of Trento. Target user groups and users are integral part of the experimentation and take part in validation of the services implemented in the testbed. It spans the range of the most advanced communications technologies, starting from a wide area DWDM optical backbone, WiMAX Wi-Fi wireless distribution/access networks, all the way to sensor networks and technologies for smart spaces. The testbed also serves as a model of a community network, planned for deployment in the Province of Trento

Signalling-Based Architectures for Impairment-Aware Lightpath Set-Up in GMPLS Networks

This paper explores the solution space for extending the signaling protocol of a GMPLS control plane for an impairment-aware path setup in transparent optical networks. Four combinations of routing and optical feasibility checking architectures based on modifications of RSVP-TE are proposed and studied. Simulation results show that a combination of hop- by-hop routing and feasibility check can be considered as a good compromise both in term of blocking probability and limited impact on the control plane. The slightly higher lightpath set-up time compared to other architectures can be tolerated especially considering the impact on the RSVP protocol current behavior as well as its independence from parameters strictly related to the network properties and topology