A performance survey on deflection routing techniques for OBS networks

In this paper, we present a survey comparing different deflection routing based techniques applied to optical burst switching (OBS) networks. For such study we consider the E-OBS architecture proposed in [1] which is an advantageous solution for OBS networks since routing decision can be taken freely inside the network without constraints on the length of the path. Under this environment, several effective routing strategies proposed in the literature are applied, namely deflection routing, reflection routing, reflection-deflection routing and multitopology routing. The aim of this study is to analyse all these techniques considering both asynchronous and synchronous burst arrivals and compare their benefits. Moreover, we focus on a quasi-synchronous burst arrival case (with bursts not perfectly aligned) and analyse the trade-off between performance and alignment.Peer ReviewedPostprint (published version

Practical Approaches for Software Components Integration in Telecommunications

Nowadays, advances in telecommunication network design and performance analysis often rely on dedicated software tools. Unfortunately, developing new tools is a very time and resources consuming activity. To rationalise development costs, existing applications can be extended. Alternatively, existing software components can be combined and integrated. Integration of heterogeneous components requires many efforts, in particular when the specific input/output data formats have to be adapted. Furthermore, the amount of data exchanged between the components can be huge and needs intermediate processing. To facilitate data exchange between tools, two concepts are presented in this paper: CostGlue and the Multilayer Network Description (MND). Their utilisation modes and the advantages they provide are illustrated through a practical example

Software Framework for Integrated Modelling and Dimensioning of Backbone Optical Networks

Modelling, dimensioning and performance analysis of optical backbone networks is the main concern of this thesis. Modelling consists in representing a network under a abstract form, simpler and easier to analyse, the model. Dimensioning is achieved when network characteristics required to fulfil given requirements are fixed a priori. Performance analysis consists in identifying the criteria characterising the network performance and in verifying whether dimensioned networks do fulfil the requirements. It also aims at estimating the deployment cost of a dimensioned network. Dimensioning a network while deploying it is unrealistic. Optical networking equipment are expensive. It is thus absurd to buy large amounts of equipment and use a part of it only. Moreover, backbone optical network spans over very large distances and is thus costly to set up. Dimensioning must thus be done based on a model, and modelling and dimensioning are therefore achieved in a integrated way. Network performances and optimal network are generally impossible to predict by means of mathematical formulations and transformations. Numerical models are thus involved to reproduce network properties. Iterative dimensioning procedures are similarly used to draw conclusions about optimal network dimensions. As both numerical models and iterative procedures involve many operations, these are most often automated. In this way, they are implemented in software programs and executed on computers. Several numerical models are presented in this thesis. Associated with corresponding dimensioning procedures, they aim at analysing the properties of various optical backbone network architectures, at devicing rationalised network layouts, and eventually at exploiting these architectures in the optimal way. Besides, the development, verification and usage of these models and procedures are time consuming activities. To speed-up them, functionalities and operations can be shared among models and procedures. They must however not only be implemented, but also organised in a structured manner within a framework. This thesis thus also presents such a software framework

Pseudo Random Numbers Generators available as Web Services

as simulation input, and they strongly influence the results. Thus, their usage and the usage of their generator need to be taken care of very well. Qualified generators are available on the web as source code or libraries. However, they require an additional middleware to adapt them to the running environments, and this can lead to misuses. This paper proposes Pseudo Random Number Generators embedded inside a Web Service for the use in simulations. This service, while offering a unique interface accessible from any platform, eases the important task of retrieving correct pseudo random numbers. The general architecture of the service is presented, as well as a reference implementation. The performance of the Web Service generator is compared to the performance of local generators

Multilayer Description of Large Scale Communication Networks

Data exchanges between various modules and tools raise interfacing difficulties in a multilayer environment. This aspect may become particularly critical in a distributed context. This paper proposes a multilayer descriptive framework for communication networks aimed at facilitating data exchange between different tools and modules. This description uses the extensible mark-up language (XML) which allows an increased flexibility and an improved visibility of relevant data

Distributed RWA tools via Web Services

Several computer tools addressing the routing and wavelength assignment (RWA) problem are available today within the research community. However, these tools have low flexibility and are difficult to use for remote or casual users. This paper shows how to allow a remote access to various existing RWA tools using Web Services. In this way, software components implementing routing and/or wavelength assignment are turned into Web Services made available over the internet and accessible through a simplified interface. This dispenses the user to perform a local implementation, allows better code reuse, and offers an easy way to confront results from distinct models. Moreover, making tools available on the web increases their credibility and visibility. In our approach, a multilayer network description (MND) format is used to describe both input data and computed results. It offers common basic structure while guaranteeing a large extensibility, and thus makes possible the interaction between various tools. The viability of this approach is illustrated through an example of implementation

Performance losses with virtualization ::comparing bare metal to VMs and containers

The use of virtualization technologies has become widespread with the advent of cloud computing. The purpose of this study is to quantify the performance losses caused by all kind of virtualization/containerization configurations. A benchmark suite consisting of tools that stress specific components and then four real applications commonly used in computing centers has been designed. A system to schedule the execution of these benchmarks and to collect the results has been developed. Finally, a procedure calling all the benchmark in a consistent and reproducible way either within a container or in a (virtual or not machine) has been implemented. These developments permitted then to compare bare metal with four hypervisors and two container runtimes as well as the mix of containers in the virtual machines. The results show that the performance differences vary greatly depending on the workload and the virtualization software used. When using the right virtualization software, the estimated the performance losses are around 5% for a container and 10% for a virtual machine. The combination of the two entails the addition of these losses to 15%. In the case of non-optimized software, a performance loss of up to 72% can be observed. We also observed that containers and virtual machines can over-perform bare-metal when it comes to file access. Overall we conclude that virtualization has become very mature and performance losses seems not to be a concern anymore

DISTRIBUTED AND COMPONENT ORIENTED TOOLS FOR COMMUNICATION NETWORKS USING WEB SERVICES

Modern communication networks are reaching a high level of complexity. As their global dimensioning and performance evaluation are very hard tasks, a multi-layer approach is generally applied to divide them in smaller problems easier to tackle. Within this approach, tools only address one or two network layers. To perform an enhanced analysis encompassing more layers, several tools, not necessarily available in the same place when the problem arises, are often required. This paper shows how to allow a remote access to various existing tools using Web Services paradigm. In this way, software components modelling network elements, layers, or computing specific functions are turned into Web Services, which are available to remote users over the internet. Accessed through a simplified interface, they can be used sequentially or in parallel to solve a specific task. This dispenses the user to perform a local implementation, allows better code reuse, and offers an easy way to confront results from distinct models. A tool accessed via a web service can be beneficial for either research or educational purposes. Moreover, making tools available on the web increases credibility and visibility of their authors. Calls to Web Service require transmitting and retrieving al

Multi-Agent Approach to Electrical Distribution Networks Control

A new approach to the configuration and operation of electrical distribution networks is proposed. Traditionally, the medium-voltage part of the electrical grid is operated in a centralized and static manner. In the context of electric sector deregulation and electric market liberalization, the pertinence of this central organization is no longer ensured.This paper presents an alternative approach based on a multi-agent system, implementing a distributed control algorithm. Concepts used in communication networks have been applied and adapted to the electrical supply system