J.E. Lopez de Vergara

Semantic management: application of ontologies for the integration of management information models

The multiplicity of network management models (SNMP, CMIP, DMI, WBEM, etc.) has raised the need of defining multiple mechanisms to allow the interoperability among all involved management domains. One basic component of such interoperability is the mapping between the information models that each domain specifies. These mappings, usually carried out with syntactical translations, can reach the semantic level by using ontologies. This article shows the advantages of using formal ontology techniques to improve the integration of current network management models.

A generic model for the management of virtual network environments

Currently, virtualization is a proven technology that potentially provides a great opportunity for industry growth and research, due to its advantages in flexibility and cost reduction. However, designing virtual network environments is a complex process that requires great effort. For this, the work proposed in this paper is focused on applying modeling techniques to characterize virtual network environments. Firstly, we have analyzed the existing approaches to model virtualized infrastructures. Based on this analysis, we have designed a generic model to characterize and manage virtual network environments based on the CIM Schema. To asses the feasibility of our approach, we have implemented a CIM client based on this model, which enables to deploy virtual network environments automatically, independently of the used underlying virtualization platform. The test results using this client demonstrated the efficiency of this implementation, which was evaluated with Xen and VMware Server.

Optimizing offset times in Optical Burst Switching networks with variable Burst Control Packets sojourn times

In this paper, we consider the case of an Optical Burst Switching (OBS) network where the Switch Control Units (SCU) do not work at the peak rate. As a consequence, some Burst Control Packets (BCPs) will have to wait in queue to be processed, and then the BCP sojourn time will be variable. On the contrary, the optical burst does not leave the optical domain and the delay suffered is close to the propagation delay. Hence, chances are that the BCP arrives late to a given switch and, in that case, the optical burst will be dropped. We propose a Load-adaptive Offset Time algorithm (LOT) that takes into account the BCP variable sojourn time for the offset time calculation. The algorithm performs on-line calculation of the Discrete Fourier Transform (DFT) of the BCPs waiting time pdf. Our findings show that this procedure is very efficient both in terms of bandwidth usage and processing load. For example, considering a Gaussian service time for the BCPs, it turns out than less than 45 coefficients are necessary to calculate the offset time for a SCU utilization factor larger than 0.1.

On the effect of concurrent applications in bandwidth measurement speedometers

Nowadays, operators are facing an increasing demand to ensure the committed bandwidth in broadband access links, both from customers and regulatory bodies. Usually, customers employ speedometers (such as Speedtest) to evaluate the access link performance. Such speedometers run in the user’s PC, concurrently with many other applications which may generate cross-traffic and reduce the processing time to the remaining applications. In this paper we analyze the impact of cross-traffic from other applications and CPU and memory occupancy due to concurrent applications in the speedometer accuracy, for a broad range of file-download and packet-train-based measurement techniques. We conclude that the packet-train technique is highly immune to cross-traffic, CPU and memory occupancy, which makes it amenable to use in general-purpose PCs running concurrent software. However, an estimation of CPU, memory occupancy and cross-traffic from other applications improves the measurement accuracy. In this regard, we present the QoS-Poll measurement software, which estimates the occupancy of system resources, including cross-traffic from other applications, and defines a region of acceptance of the bandwidth measurement in terms of the previous system parameters. The results of a QoS-Poll measurement campaign (more than 75 households) are also reported, showing excellent measurement accuracy.

A model-driven configuration management methodology for testbed infrastructures

Testbeds are controlled experimentation platforms where solutions (software, architectures, etc.) can be developed, deployed and tested in an environment that resembles real utilization conditions. This paper describes a model-driven methodology for automatic testbed reconfiguration which solves the problems of manual interaction and inter-testbed scenario reutilization. It is based in a high-level testbed-independent model of the desired scenario (so it can be applied to any testbed in general) which is particularized to testbed-specific scenario models for automatic deployment and management by model-based tools. The paper also details our practical experiences applying the methodology to two quite different use cases: VNUML-based virtual testbeds and the GMPLS-enabled optical network of ADRENALINE testbedreg (each one with its own model-based automatic deployment tools), thus assessing the feasibility and generality of the proposed approach.

A queueing equivalent thresholding method for thinning traffic captures

In the development of accurate capacity planning and network resource dimensioning models, network operators must handle representative information about the traffic volumes traversing its network. However, the amount of traffic measurements available over which to perform such analysis, processing and storage is overwhelming. For this reason, the research community has understood the importance of finding an effective mechanism to reduce (or subsample) such huge amount of data, with minimum loss of information. More specifically, this work considers the traffic volume traversing a given router per unit of time, which can be obtained by periodically polling the counters of the interfaces table via SNMP. We further propose a mechanism to downsample such traffic time-series using multi-resolution analysis with wavelets, and evaluate the optimal subsampling level based on comparing the queueing behavior of the subsampled and original signals at the output of a router. This mechanism is more related to network performance than conventional comparison levels, since queueing delay is a very representative QoS metric. The method presented in this paper has been applied to an extensive set of real measurements collected from RedlRIS, the Spanish National Research Network. The results show that it is possible to reduce the data to one fourth of its original size for the traffic generated by most analyzed universities, and even to one eighth for data collected from routers with more aggregated traffic, both with a high level of confidence.

Traffic monitoring for assuring quality of advanced services in future internet

Services based on packet switched networks are becoming dominant in telecommunication business and both operators and service providers must evolve in order to guarantee the required quality. Increasing bandwidth is no longer a viable solution because of the business erosion for network operators which cannot expect revenues due to the large investments required to satisfy new applications demand of bandwidth. This paper presents devices and a specific architecture of services monitoring platform that allows network operators and service providers to analyze the perceived quality of service and check their service level agreements. Thus, a cost-effective service management, based on direct IP traffic measuring, can be supported on integrated monitoring systems to provide network-centric mechanisms for differentiated quality of service, security and other advanced services.

A system for monitoring, assessing and certifying Quality of Service in telematic services

This work presents a knowledge-based system and architecture for the formalization of quality of service (QoS) characteristics and measurement methods in telematic services, and for the collection, distribution and assessment of the QoS information obtained using these methods. The solution makes use of ontologies and reasoning technology to define and compare QoS information. The system can help customers to select the service offer that best fits their quality requirements. Providers will use it to detect when the delivered service fails to fulfill the quality agreements that they signed with customers.

Leveraging open source platforms and high-level synthesis for the design of FPGA-based 10 GbE active network probes

Nowadays, 10 Gb/s networks are becoming more and more widespread. Consequently, there is an increasing need for testing equipment for those networks, to measure parameters such as throughput, delay, jitter, packet loss rate, etc. Network testing equipment can be either active or passive, depending on whether it injects traffic or simply monitors packets in network links. In this paper we focus on active network probes, particularly those which are based on injection of packet trains. This type of probes have the advantage of causing little interference with existing network traffic, even though they are quite effective to measure several network parameters such as throughput or delay. Here, we take advantage of the open source NetFPGA project to implement a 10 GbE active monitoring probe based on the packet-train technique. In order to reduce development time, we used NetFPGAs OSNT (Open Source Network Tester) monitor project as a starting point, and we also used high-level synthesis tools (namely, Vivado-HLS) to implement the IP core in charge of computing network parameters. Such two design strategies turned out to be very effective both in terms of coding productivity and accuracy of measurements. Actually, the quality of measurements was found to be much better than that obtained with software solutions running on commodity servers, though the development effort was not significantly higher, thanks to the use of open source platforms and high-level synthesis techniques.

Measurements and Measurement Tools in OpenLab: Use Cases with Measurement Data Ontologies

In this chapter we review the network measurement tools and instruments that are in place in the FP7 OpenLab project, which provides a set of different network testbeds. We also focus on the problem of data heterogeneity, which comes from the fact that different measurement tools will provide data in different formats and structured in different ways. Therefore, a common information model becomes necessary and the OpenLab ontology-based solution is presented. Such ontology is being standardized by an Industry Specification Group at ETSI, resulting in the first ever standard on network measurement data ontologies.