Mathematical Analysis of Delay Line to Wavelength Allocation Algorithmsin Optical Networks

Optical technology as a promising infrastructure is imminent in Internet core and metro networks to meet the ever increasing bandwidth demand from a large number of users in scientific, academic, and business communities, as well as in military and other government agencies. Recently, optical burst switching, or OBS, which represents a balance between circuit and packet switching, has opened up some stimulating new challenges in optical networking. Several analytical models of different aspects of optical technology in the Internet core, such as optical interconnections and OBS, have been proposed in the literature. To the best of our knowledge these models, however, have been ignored the impatience of messages traveling through optical switches in the Internet core. Fiber delay lines are employed in an optical switch to obtain enough time in order not to overload a potential congested downstream switch and henceforth avoid contention. This paper describes a novel analytical model to compare the performance of two different forwarding methods in optical burst switches, one which employs wavelength converters in middle switches and one that forces bursts to have the same wavelength throughout their path. One of the main features of the proposed model is the use of results from queuing systems with impatient customers to capture the effects of the impatience of the messages passing through delay lines in a switch. The validity of the model for both forwarding methods is demonstrated by comparing analytical results with those obtained from simulation experiments.