PI-OBS: a Parallel Iterative Optical Burst Scheduler for OBS networks

This paper presents the PI-OBS algorithm, a parallel-iterative scheduler for OBS nodes. Conventional schemes are greedy in the sense that they process headers one by one. In PI-OBS, all the headers received during a given time window are jointly processed to optimize the delay and output wavelength allocation, applying void filling techniques, and allowing traffic differentiation. Results show a similar or better performance than the LAUC-VF algorithm, commonly used as a performance bound for OBS schedulers. The PI-OBS scheduler has been designed to allow parallel electronic implementation similar to the ones in VOQ schedulers, with a deterministic response time.This research has been partially supported by the MEC projects TEC2007-67966-01/TCM CON-PARTE-1, and TEC2008-02552-E, and it is also developed in the framework of "Programa de Ayudas a Grupos de Excelencia de la R. de Murcia, F. Séneca"

A cost-effective approach to optical packet/burst scheduling

Optical Burst and Packet Switching are being considered as the most promising paradigms to increase bandwidth efficiency in IP over DWDM networks. In both cases, due to statistical multiplexing, a scheduling policy is needed to solve contentions at the node level caused by more than one burst/packet directed to the same output channel. The scheduling may be performed in the wavelength, time and space domains, turning this problem into a choice of the best available resource in the different domains. Because of the very large bandwidth on the wavelength channels, the burst/packet arrival rate at the network nodes is very high and therefore the time available to take the scheduling decision is very limited. As a consequence, whatever scheduling policy is adopted, it must be implemented in an extremely effective way in terms of computational complexity. This paper is focused on a cost-effective solution to the scheduling problem, which is not based on typical search algorithms and whose complexity can be made almost independent of the dimension of the resource set to be searched