Optical burst switching: Challenges, solutions and performance evaluation

Optical Burst Switching (OBS) is a prospective networking technology that can carry mankind to the next generation information superhighways. Networking services like HDTV, video-conferencing, grid computing and other bandwidth-hungry applications can see a new day with OBS potentially providing humongous throughput and utilization at the lower layers. The implementation benefits of OBS over the pure-breed optical packet switching (OPS) makes it a favorable technology for both academia and industry to ponder upon. Like any other technology growing through its infancy, OBS faces several challenges and provides several open research topics for researchers. In this dissertation, a few burning issues which we think are important are identified and solutions for them are proposed.; In the first part, we propose an implementation of an OBS metropolitan area ring network. We propose several access protocols to efficiently transport different classes of traffic across the ring nodes. Three classes of traffic are identified, one of which has stringent end-to-end delay requirements and the other two require minimal or zero burst loss. Access protocols based on Token and Acknowledgement techniques are considered and then developed to accommodate the above requirements. Extensive simulations are then carried out to depict the behaviour of each of the protocols and to verify that our objectives are met.; In the second part, we propose a congestion control architecture for OBS mesh networks. Congestion in OBS networks leads to extensive burst losses due to bufferless nature of these networks. We identify several promising techniques which can be investigated upon to solve the congestion problem. We finally propose a congestion control architecture with multi-tier congestion avoidance schemes for different classes of traffic.; In the third part, we present both an analytical solution and a numerical approach for modeling limited-range wavelength conversion in an OBS switch. The analytical solution is a queueing model with a product-form solution which provides approximate results. Initially, the product-form solution can accommodate very small degrees of conversion. We then propose a heuristic solution that builds upon the product-form solution to yield a large scale approximation technique. This technique can evaluate blocking probabilities for both very large wavelengths and degrees of conversion. A numerical approach to the above problem is then considered which can also be used to get better approximations with the previous analytical approach. Performance results indicate that the straight-forward approach of OBS networks may result in less than expected bandwidth utilization, and thus the need to investigate better ways of realizing this technology.