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

Bandwidth measurements and capacity exploitation in Gigabit Passive Optical Networks2014 Fotonica AEIT Italian Conference on Photonics Technologies

We report an experimental investigation on the measurement of the available bandwidth for users in Gigabit Passive Optical Networks (GPON) and the limitations caused by the Internet protocols. 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 the case of TCP. In this ultrabroadband environment we also investigated on use of the UDP and of the multisession TCP. A correlation in terms of QoE is also reported

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

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

MEASUREMENT PLANE FOR INTERNET AND THE IMPLEMENTATION FOR SERVICE LEVEL AGREEMENT VERIFICATION

To take into account all the internet future evolutions network management will require many automatic processes to allocate suitable resources according to user and operator necessities, with fast response times and with a control managed by a centralized entity. This is the base concept of the Software Defined Networking (SDN), where the central entity is the Orchestrator [ [1], [2], [3]]. Furthermore, one of the fundamental task for current and future network implementation and maintenance is the control of several network parameters, including capacity, performance, but overall user satisfaction, that currently is meant in terms of Quality of Service (QoS). Recently another important aspect is the power consumption. Therefore, for a correct network management, it is fundamental to take into account all these aspects. The QoS control will require actions both in the access and in the core segment [4]. The control of the QoS can be obtained at different levels as for an example: a) from the user perception point of view (or Quality of the Experience, QoE) [5]; b) in terms of user bandwidth, and in this case we can distinguish different "bandwidths" according to the OSI stack [5], in particular we can refer to the line capacity offered by the ISP (Layer 1-2, L1-2, of the OSI stack), the bandwidth at disposal at TCP level (throughput, L4) and the bandwidth at disposal at application level (L7); c) passive monitoring of the traffic in some points of the network [ [6]- [7]]; d) route analysis of the packets. The correlation among all the measurement methods, [a, b, c, d], allows us to have a good view of the network performance and in particular to define problems and anomalies that occurs in the network. It has to be pointed out that this is one of the aims of "quality measurement plane" of the FP7 MPLANE project. The detection of network problems and anomalies can be a reference plane for automatic actions in the network in order to improve the performance both for the users and for ISP (for an instance in terms of Opex), and such a process could be also much important for Over the Top operators (OTT). Conversely the theme of Energy Saving in telecommunication network has been treated in the framework of the EU FP7 project TREND, where in particular several investigations were carried out on power consumption and on the technique and algorithms to save energy, as for an example by switching off links (physical and logic) in periods of low traffic load. Therefore one of the most appealing topic for future networks will be the introduction of a QoSPower management based on SDN approach and this is the subject of my Thesis. In particular for the work of my PhD thesis I participated into two European Research projects that have allowed me to deeply study several topics regarding energy saving in FP7 TREND project and QoS in FP7 mPlane project. On both projects very interesting and innovative researches has been published, on which I have been part of

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 and to unveil design and implementation defects. To tackle this fragmentation and visibility problem, we have recently conceived mPlane, a distributed measurement platform which runs, collects and analyses traffic measurements to study the operation and functioning of the Internet. In this paper, 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) which 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