Flexible simulators for OBS network architectures

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

Network-based Parallel Computing over ATM Using Improved SSCOP Protocol

In this paper, we address the problem of supporting network-based parallel computing, usually known in the literature as High Performance Distributed Computing (HPDC), over ATM networks. For this purpose, we consider a logically separate subnetwork for HPDC applications. After presenting an architectural reference model for the HPDC subnetwork and distinguishing which functions should be installed over the ATM network in order to satisfy the needs of HPDC applications, we suggest two different modifications of the loss recovery mechanism of Service-Specific Connection Oriented Protocol (SSCOP) that aim at optimizing communications by taking advantage of both the special properties of HPDC traffic and the cell-based nature of ATM. The performance of these mechanisms is evaluated and compared with that achieved by the standard mechanism of the SSCOP protocol. The results show that when the ATM network experiences high load and the HPDC applications make an intensive use of arrays, SSCOP ..

PHLAME: A Physical Layer Aware MAC Protocol for Electromagnetic Nanonetworks

Nanotechnology is enabling the development of integrated devices just a few hundred nanometers in size. Communication among these nano-devices will boost the applications of nanotechnology in the biomedical, environmental and military fields. Within the communication alternatives at the nanoscale, the state of the art in nanomaterial research points to the Terahertz band (0.1-10 THz) as the frequency range of operation of graphene-based electromagnetic (EM) nano-transceivers. This frequency band supports very large transmission bit-rates and enables simple communication mechanisms suited to the limited capabilities of nano-devices. Due to an expectedly very large number of nano-devices sharing the same channel, it is necessary to develop new Medium Access Control (MAC) protocols which will be able to capture the peculiarities of nanonetworks in the Terahertz band. In this paper, PHLAME, a physical layer awar

NanoSim: A Simulation Framework for Diffusionbased Molecular Communication

* Carrying fundamental research on nano communication networks * Educate and train the new generation student

Joint routing and wavelength allocation subject to absolute QoS constraints in OBS networks

From the network layer perspective, the problem of burst losses is one of the most challenging problems which restrain the development of optical burst switching (OBS) networks. Indeed, OBS is a buffer-less technology and the consequent lack of guarantees for data delivery may affect significantly the quality of service (QoS) perceived by end users. To overcome these obstacles, dedicated network mechanisms and design methods are required for QoS provisioning in the network. With this end in view, in this paper, we present a traffic engineering (TE) approach to support the end-to-end traffic delivery with absolute QoS guarantees, in terms of burst losses, in an OBS network. We focus on the establishment of explicit routing paths and minimum allocation of wavelength resources in network links under the requirement that certain absolute level of burst loss probability for a given set of traffic demands is guaranteed. In this paper, we call such an off-line problem the virtual topology (VT) design problem. Since the VT design problem is NP-complete, as an alternative to the mixed integer linear programming formulation, we develop a local search heuristic algorithm to solve it. Moreover, we focus on a dynamic OBS network scenario, where the offered traffic is subject to a change. In this context, we propose an on-line VT maintenance mechanism that is responsible for traffic admission control and adaptation of the VT to traffic changes. Eventually, proposed algorithms and mechanisms for the TE-driven end-to-end QoS approach are verified both numerically and by means of network simulations for a number of network scenarios

12 th POLISH TELETRAFFIC SYMPOSIUM PSRT2005 PSRT RECOVERY, FAIRNESS AND CONGESTION CONTROL MECHANISMS IN RPR NETWORKS

The paper describes fundamental features of RPR (Resilient Packet Ring- IEEE 802.17 standard). It focuses on proposals how to improve fairness mechanism and to increase network efficiency in state of congestion. Recovery mechanisms are also discussed, with presented analytical and simulation results. The goals of paper are threefold. At first, we show RPR main features and describe its current status. Secondly, we present main recovery and resilience features of RPR and propose solutions for improving both fairness and congestion control. Finally, a new concept, the enhanced hold-off timer (EHOT) is introduced improving recovery actions in multilayer networks. Some simulation results are presented in order to illustrate advantages of proposed solution. Index terms-Resilient Packet Ring (RPR), OTN, congestion control, fairness, resilience 1

Why optical packet switching failed and can elastic optical networks take its place?

In this special issue devoted to the memory of Prof. Fabio Neri we would like to look back at the time of the international research projects where some of us collaborated with him. On the basis of our personal experience of the time and the current viewpoint, we will discuss why Optical Packet Switching (OPS) is a technology that never came to market in spite of the great amount of research that was devoted to it. Then we will explore how Elastic Optical Network came to the stage more recently, somewhat overcoming the OPS technical proposal both in the interest of the researchers as well as of the industry

Adaptive Multipath Routing of Connectionless Traffic in an ATM Network

Traffic management in B ISDN is the focus of interest of many research studies. Two important open problems in this area are the establishment of congestion control procedures in ATM networks, and the development of a mechanism to support connectionless (CL) sessions on top of the ATM network. Although both aspects may be studied separately, they are closely related and have an effect on each other. This paper addresses the problem of connectionless traffic support on top of an ATM network. We propose a solution based on an adaptive multipath routing scheme which is added to the routing algorithm currently implemented at the Inter--Working Units (IWUs). We present a scheme that distributes Connectionless Protocol Data Units (CL PDUs) among multiple Virtual Paths (VPs) according to the utilization of the links of these VPs. The utilization of the VPs is determined by using a feedback mechanism. We present simulation studies to show the effectiveness of the proposed adaptive multipath ro..