We compute analytically burst blocking probabilities in an OBS switch when limited-range wavelength conversion is employed. Two separate queueing models are proposed and analyzed approximately; one for the case where the degree of conversion d is 1 or 2, another for large values of d. The arrival process of bursts is assumed to be an IDLE-ON process. The accuracy of these queueing models was tested against simulation. We show numerically that in order to keep the burst blocking probability within an acceptable level, the utilization of each wavelength has to be low.

We develop an analytical model for modeling limited-range wavelength conversion employed in an OBS switch. The system is modeled as a simultaneous resource possession problem. We propose a productform solution which calculates approximate blocking probabilities for degree of conversion d = 1, 2 and for large number of wavelengths. We then propose an approximate model for large values of d. The output of our model was verified with simulation results.

Performance studies point to the fact that in an OBS network, the link utilization has to be kept very low in order for the burst loss probability to be within an acceptable level. Various congestion control schemes have been proposed, such as the use of converters, fiber delay lines, and deflection routing. However, these schemes do not alleviate this problem. It is our position that in order for OBS to become commercially viable, new schemes have to be devised that will either guarantee zero burst loss, or very low burst loss at high utilization. In a previous paper [Ij, we described effective zero burst loss schemes for OBS rings. In this paper, we present a zero burst loss scheme for star OBS topologies. Further research into the topic is required.

Several access protocols are proposed to support different service classes in an optical burst switched ring. Their performance is evaluated through simulation. Various performance metrics such as throughput, utilization, burst loss rate, end-to-end delay and fairness are used to analyze the behavior of each protocol.

Abstract. Several access protocols are proposed to support different service classes in an optical hurst switched ring. Their performance is evaluated through simulation. Various performance metrics such as throughput, utilization, hurst lass rate, end-ta-end delay and fairness are used to analyze the hehaviour of each protocol.