Edion Tego

Facing the Reality: Validation of Energy Saving Mechanisms on a Testbed

Two energy saving approaches, called Fixed Upper Fixed Lower (FUFL) and Dynamic Upper Fixed Lower (DUFL), switching off idle optical Gigabit Ethernet (GbE) interfaces during low traffic periods, have been implemented on a testbed. We show on a simple network scenario that energy can be saved using off-the-shelf equipment not explicitly designed for dynamic on/off operation. No packet loss is experienced in our experiments. We indicate the need for faster access to routers in order to perform the reconfiguration. This is particularly important for the more sophisticated energy saving approaches such as DUFL, since FUFL can be implemented locally.

Multilevel bandwidth measurements and capacity exploitation in gigabit passive optical networks

The authors report an experimental investigation on the measurement of the available bandwidth for the users in gigabit passive optical networks (GPON) and the limitations caused by the Internet protocols, and transfer control protocol (TCP) in particular. We point out that the huge capacity offered by the GPON highlights the enormous differences that can be showed among the available and actually exploitable bandwidth. In fact, while the physical layer capacity can reach value of 100 Mb/s and more, the bandwidth at disposal of the user (i.e. either throughput at transport layer or goodput at application layer) can be much lower when applications and services based on TCP protocol are considered. In the context of service level agreements (SLA) verification, we show how to simultaneously measure throughput and line capacity by offering a method to verify multilayer SLA. We also show how it is possible to better exploit the physical layer capacity by adopting multiple TCP connections avoiding the bottleneck of a single connection.

Unveiling Network and Service Performance Degradation in the Wild with mPlane

Unveiling network and service performance issues in complex and highly decentralized systems such as the Internet is a major challenge. Indeed, the Internet is based on decentralization and diversity. However, its distributed nature leads to operational brittleness and difficulty in identifying the root causes of performance degradation. In such a context, network measurements are a fundamental pillar to shed light on and unveil design and implementation defects. To tackle this fragmentation and visibility problem, we recently conceived mPlane, a distributed measurement platform that runs, collects, and analyzes traffic measurements to study the operation and functioning of the Internet. In this article, we show the potentiality of the mPlane approach to unveil network and service degradation issues in live operational networks, involving both fixed-line and cellular networks. In particular, we combine active and passive measurements to troubleshoot problems in end-customer Internet access connections, or to automatically detect and diagnose anomalies in Internet-scale services (e.g., YouTube) that impact a large number of end users.

Exploiting hybrid measurements for network troubleshooting

Network measurements are a fundamental pillar to understand network performance and perform root cause analysis in case of problems. Traditionally, either active or passive measurements are considered. While active measurements allow to know exactly the workload injected by the application into the network, the passive measurements can offer a more detailed view of transport and network layer impacts. In this paper, we present a hybrid approach in which active throughput measurements are regularly run while a passive measurement tool monitors the generated packets. This allows us to correlate the application layer measurements obtained by the active tool with the more detailed view offered by the passive monitor. The proposed methodology has been implemented following the mPlane reference architecture, tools have been installed in the Fastweb network, and we collect measurements for more than three months. We report then a subset of results that show the benefits obtained when correlating active and passive measurements. Among results, we pinpoint cases of congestion, of ADSL misconfiguration, and of modem issues that impair throughput obtained by the users.

Experimental Investigation on Transmission Control Protocol Throughput Behavior in Optical Fiber Access Networks

ABSTRACT This article describes an experimental investigation on the behavior of transmission control protocol in throughput measurements to be used in the verification of the service-level agreement between the Internet service provider and user in terms of line capacity for ultra-broadband access networks typical of fiber-to-the-x architectures. It is experimentally shown different conditions in high bandwidth-delay product links where the estimation of the line capacity based on a single transmission control protocol session results are unreliable. Simple equations reported in this work, and experimentally verified, point out the conditions in terms of packet loss, time delay, and line capacity, that allow consideration of the reliability of the measurement carried out with a single transmission control protocol session test by adopting a suitable measurement time duration.

Quality of service management based on Software Defined Networking approach in wide GbE networks

This work experimentally demonstrates how to control and manage user Quality of Service (QoS) by acting on the switching on-off of the optical Gigabit Ethernet (GbE) interfaces in a wide area network test bed including routers and GPON accesses. The QoS is monitored at the user location by means of active probes developed in the framework of the FP7 MPLANE project. The network topology is managed according to some current Software Defined Network issues and in particular an Orchestrator checks the user quality, the traffic load in the GbE links and manages the network interface reconfiguration when congestion occurs in some network segments.

The TREND experimental activities on “green” communication networks

Aimed at answering important questions about the energy demand of current telecom infrastructure and the design of sustainable and energy-efficient future networks, the research of a number of European partners is brought together in the TREND project. In this paper we present the achievements of the Work Package coordinating the experimental activities of the project - WP4. Although not presenting a completely finished portrait yet, the results shown help building a better global view on the “big picture” in the field of energy-efficient networking.

Role of a Measurement Plane to Monitor and Manage QOS in Optical Access Networks

ABSTRACT In this work, we propose a measurement plane for Software Defined Networking (SDN) architectures for monitoring the network performance and supporting the orchestrator in managing the optical link resources. Concerning the measurement plane, we consider two models that we adopted in other contests: Misurainternet and mPlane. However, due to better scalability, the tests reported in this paper refer to mPlane that has been used in a SDN environment based on Fiber to the X (FTTX) accesses, with procedures of the central unit (orchestrator) that automatically manages GbE links in a regional network. The choices of the orchestrator are based on information received by a reasoner that analyzes the network performance elaborating data detected by active and passive probes. The mPlane-SDN architecture is tested in field measurements concerning FTTX accesses and in Lab to verify the resource allocations in case of traffic congestion. Furthermore, we also show the potentiality of our architecture to evolve toward a distributed controller approach with important advantages for telecom operator strategies.

Quality of Service monitoring adopting correlation among active and passive measurements: The experience from the FP7 mPlane project

In this work we report the final results of the field demonstration of the European FP7 mPlane project concerning the evaluation of the network performance with particular details regarding the access Quality of Service and traffic monitoring. We show how the proposed and experimented architecture of this measurement plane is fundamental for many future internet evolutions concerning user perception, content popularity web quality and network management. Here we point out the results dedicated to service level agreement verification and certification with analysis of the correlation between passive and active measurements in order to understand some causes concerning network and service anomalies.