Milos Kozak

VM migration measurement and failure detection

This paper tackles migration of virtual machines, and the migration reliability. The migration is seen as a reliable operation, but this assumption is not true and almost no work on this topic has been published. In order to quantify the migration successful rate, we designed and implemented framework for autonomous migration evaluation, network availability testing, and reporting. This framework is introduced in this paper and its configuration is described. This framework is very unique because of its modular architecture and orchestration independence. We use this framework in order to quantify the migration successful rate, so we prepare statistically reliable test. Based on this test we formulated a mathematical hypothesis and we found that only 87% of migrations successfully finish. This is very low value which is very alarming because the experiment was carried out on the testbed which is based on the most recent technologies.

On regenerator placement in loss-less optical burst switching networks

Optical burst switching suffers from burst contention, which can occur even under low load. This issue was investigated by Coutelen et al., 2009 and led to the CAROBS framework. Therein, the authors considered burst concatenation, and with the recourse to wavelength conversion throughout signal regeneration, can resolve all burst contentions, offering then a loss-free OBS framework. However, CAROBS does not take into account physical layer impairments, which can lead to OSNR degradation and ultimately optical burst losses. In this paper, we investigate how many additional optical regenerators need to be introduced in order to overcome those physical impairments in translucent OBS networks. We propose two different heuristics in order to optimize the regenerator locations. Numerical results are presented in order to both investigate the number of regenerators that need to be installed in order to minimize burst loss, ultimately to reach no burst loss, and the signal degradation due to physical layer impairments.

On the efficiency of stream line effect for contention avoidance in optical burst switching networks

The OBS paradigm is a very promising all-optical transmission paradigm; however, OBS still suffers from burst losses because of burst contentions. Consequently, several loss-less approaches were proposed by various authors. In this paper, we investigate further one of them, the CAROBS framework, originally proposed by Coutelen et al. (2010) 15. CAROBS uses electronic buffering for contention resolution that requires careful routing strategies in order not to entail too many new contentions, and then buffering as a result of these contentions. This led us to look at the stream-line effect in order to devise efficient routing. The streamline effect has not yet been much exploited except for its straightforward implementation. Firstly, we empirically verify the impact of buffering within a stream-line effect framework, and discuss the significance of the results. Secondly, we devise an optimized request provisioning taking advantage of the stream-line effect with a compact integer linear programming (ILP) model, and then with a decomposition ILP model. Thirdly, we proceed with extensive numerical experiments. We run a time domain analysis of the routing obtained from the last ILP model for four referential network topologies. Results show very appealing properties of the CAROBS framework, and in particular, a maximal wavelength efficiency higher than 70%.

Benchmarking methodology for IP testing in industrial networks

This paper aims to describe a benchmarking methodology for testing the performance of IP protocols in industrial and control networks with regard to the deployment of Smart Grids. Based on the ITU recommendation and definitions, the paper summarizes the general communication requirements for ICT networks and confronts them with the requirements set out in the standards for specific types of industrial and control network implementations such as electrical power industry, water industry, transport industry, etc. The paper provides qualitative parameters, which aim to characterize the transmission characteristics of IP protocol based on confrontation of the communication requirements. It is necessary to define general data streams that are typical for industrial and control networks and measurement scenarios for measuring these transmission characteristics. Finally, the paper defines the minimum topology of test network and minimal configuration of network elements where the methodology for testing IP protocols is demonstrated.

On application of least-delay variation problem in ethernet networks using SDN concept

The goal of this paper is to present an application idea of SDN in Smart Grids, particularly, in the area of L2 multicast as defined by IEC 61850-9-2. Authors propose an Integer Linear Formulation (ILP) dealing with a Least-Delay-Variation multicast forwarding problem that has a potential to utilize Ethernet networks in a new way. The proposed ILP formulation is numerically evaluated on random graph topologies and results are compared to a shortest path tree approach that is traditionally a product of Spanning Tree Protocols. Results confirm the correctness of the ILP formulation and illustrate dependency of a solution quality on the selected graph models, especially, in a case of scale-free topologies.