Algorithms for quality of service provisioning and enhancement in optical burst switched networks

Ph.DDOCTOR OF PHILOSOPH

A Priority Based Optical Header Contention Resolution in Optical Burst Switching Networks

OBS is a promising switching paradigm for the next-generation Internet.In OBS, data packets are assembled into variable size data burst which are transmitted optically over Dense Wavelength Division Multiplexing(DWDM)networks without O/E/O conversion. The control packet is sent before the data burst to reserve resources and configure switches along the path .The control packet is sent along the separate control channel and goes through O/E/O conversion. We have discussed various OBS signalling protocols and Burst Scheduling Algorithms. As the data channel bandwidth will grow it will lead to the overloading of the control path. In this thesis we have proposed an algorithm to resolve the contention of the optical header. The algorithm assigns the priority to each control packet arriving at the same time .The control packet with highest priority is selected for processing. Simulation results have shown that the technique is effective in improving the throughput

Connection routing and configuration in optical burst switching networks

Ph.DDOCTOR OF PHILOSOPH

Adaptive traffic distribution in optical burst switching networks

Master'sMASTER OF ENGINEERIN

Design And Analysis Of Effective Routing And Channel Scheduling For Wavelength Division Multiplexing Optical Networks

Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and mesh topologies, the U.S. Long-Haul topology, the Abilene high-speed optical network used in Internet 2, the Toronto Metropolitan topology and the European Optical topology. Optical routing protocols previously published in the literature have largely ignored the noise and timing jitter accumulation caused by cascading several wavelength conversions along the lightpath of the data burst. This dissertation has identified and evaluated a new constraint, called the wavelength conversion cascading constraint. According to this constraint, the deployment of wavelength converters in future optical networks will be constrained by a bound on the number of wavelength conversions that a signal can go through when it is switched all-optically from the source to the destination. Extensive simulation results have conclusively demonstrated that the presence of this constraint causes significant performance deterioration in existing routing and wavelength assignment (RWA) algorithms. Higher blocking probability and/or worse fairness have been observed for existing RWA algorithms when the cascading constraint is not ignored. To counteract the negative side effect of the cascading constraint, two constraint-aware routing algorithms are proposed for OCS networks: the desirable greedy algorithm and the weighted adaptive algorithm. The two algorithms perform source routing using link connectivity and the global state information of each wavelength. Extensive comparative simulation results have illustrated that by limiting the negative cascading impact to the minimum extent practicable, the proposed approaches can dramatically decrease the blocking probability for a variety of optical network topologies. The dissertation has developed a suite of three fairness-improving adaptive routing algorithms in OBS networks. The adaptive routing schemes consider the transient link congestion at the moment when bursts arrive and use this information to reduce the overall burst loss probability. The proposed schemes also resolve the intrinsic unfairness defect of existing popular signaling protocols. The extensive simulation results have shown that the proposed schemes generally outperform the popular shortest path routing algorithm and the improvement could be substantial. A two-dimensional Markov chain analytical model has also been developed and used to analyze the burst loss probabilities for symmetrical ring networks. The accuracy of the model has been validated by simulation. Effective proactive routing and preemptive channel scheduling have also been proposed to address the conversion cascading constraint in OBS environments. The proactive routing adapts the fairness-improving adaptive routing mentioned earlier to the environment of cascaded wavelength conversions. On the other hand, the preemptive channel scheduling approach uses a dynamic priority for each burst based on the constraint threshold and the current number of performed wavelength conversions. Empirical results have proved that when the cascading constraint is present, both approaches would not only decrease the burst loss rates greatly, but also improve the transmission fairness among bursts with different hop counts to a large extent

Performance issues in optical burst/packet switching

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-01524-3_8This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms

Quality of service in optical burst switching networks

Tese dout., Engenharia Electrónica e Computação, Universidade do Algarve, 2009Fundação para e Ciência e a Tecnologi

Telecommunications Networks

This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing

Dynamic routing and load balancing in IP-over-WDM networks

Master'sMASTER OF ENGINEERIN

How far can we go with OBS networks

Optical Burst Switching (OBS) was proposed ten years ago as an alternative switching paradigm in order to overcome some of the drawbacks of Optical Circuit Switching (OCS). While OBS is no more necessarily perceived as a competitor to OCS, but more of a more adapted switching for networks with bursty and highly dynamic traffic, there is still a debate around OBS, i.e., how far an OBS network can go in terms of throughput with no or limited burst losses. This thesis attempts to answer this question by investigating how to devise an upper bound on the throughput of an OBS network, assuming no recourse to electrical buffering is made at any intermediate node. We investigate both the burst scheduling and routing issues, with a larger focus on routing in three directions: (i) exploration of weighted k -shortest paths, (ii) revisiting load balancing, (iii) examining tree decomposition. Simulations have been conducted to compare and evaluate each of the new ideas with adapted (with respect to throughput upper bounding) previously proposed routing algorithms on different network and traffic instances. A comparison of the best upper bound with lower bounds obtained under various assumptions is presente