Techniques for improved scheduling in optical burst switched networks

Abstract

Optical burst switching (OBS) has emerged as a viable switching alternative in backbone optical networks since it can support high data rates with an intermediate granularity compared to wavelength routing and optical packet switching. At the edges of an OBS cloud, packets are assembled to form bursts which enter the network core and are switched on the fly using bandwidth previously reserved by their control packets at each node. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, i.e. the scheduling of bursts. This paper proposes two new techniques which are shown to improve burst scheduling algorithms by lowering their complexity. The first proposed technique is based on a triangular estimator that defines a ldquodrop zonerdquo; bursts that fall into this area are considered to have a very low probability of finding a suitable wavelength and as such, no effort is made to schedule them. According to the second approach, the drop zone is defined dynamically based on the burst drop history. Simulation results show that both approaches yield burst drop rates marginally higher or identical to the LAUC-VF scheduling algorithm while reducing the number of channel or void checks and thus the algorithm complexity and execution time.