Since the OBS paradigm has become a potential candidate to cope with the needs of the future all optical networks, it has really caught the attention from both academia and industry worldwide. In this direction, OBS networks have been investigated under many different scenarios comprising numerous architectures and strategies. This heterogeneous context encouraged the development of various simulation tools. In this paper we present our novel Java-based OBS network simulator called JAVOBS. We discuss its architecture, study its performance and provide some exemplary results that point out its remarkable flexibility. This flexibility should permit an easy integration of upcoming new network protocol designs but also support changing and evolving research goals.

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Since the OBS paradigm has become a potential candidate to cope with the needs of the future all optical networks, it has really caught the attention from both academia and industry worldwide. In this direction, OBS networks have been investigated under many different scenarios comprising numerous architectures and strategies. This heterogeneous context encourages the development of flexible simulation tools. These tools should permit both an easy integration of any possible new network protocol design and a rapid adaptation to different performance target goals. In this paper, we present two OBS network simulators, namely, a C-based simulator (ADOBS) and our novel Java-based simulator (JAVOBS). We compare their performances and we provide some exemplary results that point out remarkable flexibility that can be achieved with the JAVOBS simulator. Keywords: optical burst switching (OBS), simulation tool, flexibility. INTRODUCTIONTo move towards IP-over-WDM architectures, various optical switching techniques have been under intensive research. Among them, three switching paradigms have appeared as potential candidates. Firstly, Optical Circuit Switching (OCS) [1] pursues a wavelength routed networking architecture with a whole wavelength as its finest granularity. However, it lacks both the flexibility and efficiency required to cope with the needs of current traffic patterns. Secondly, in the Optical Packet Switching (OPS) approach [2], each packet is sent into the network with its own header. This header is going to be either electronically or all-optically processed at each intermediate node while the packet is optically buffered. Although OPS may be seen as both the natural choice and conceptually ideal for the future all-optical networks, current optical technology is still immature and not able to overcome its exigencies. Finally, in order to provide optical switching for next-generation Internet traffic in a flexible yet feasible way, the Optical Burst Switching (OBS) paradigm was proposed in [3]. In an OBS network, a burst control packet (BCP) is sent out-of-band both to reserve all resources and to set up the path for its burst of data, which will be sent optically after an offset time in a cut through manner. In this way, OBS allows for an efficient use of resources without the need of optical buffering at any intermediate node. Although it can be seen as an intermediate step of the migration from OCS to OPS, OBS has emerged as a more competitive choice for the transmission of data traffic in the near future. In essence, OBS combines the best from both OCS and OPS while avoiding their shortcomings. Consequently, OBS has received an increasing amount of attention from the optical research community and has become, nowadays, a research field of its own.OBS networks display a complex structure and the design of their constituent elements offers several degrees of freedom. So far, much of the research on OBS networks has been conducted through theoretical analysis. Undeniably, the analytical approach...

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.