Performance evaluation of a new technique for IP support in a WDM optical network: optical composite burst switching (OCBS)

Abstract

In this paper, the optical composite burst switching (OCBS) technique is proposed to be implemented in an all-optical backbone network to support Internet protocol (IP) traffic. The OCBS is based on two main features. First, several IP packets are assembled in a single macropacket, called burst. Second, the burst contention in an optical switch is handled by means of two techniques, the wavelength dimension and the burst-dropping (BD) technique. Different from traditional optical burst switching, where an entire burst is discarded when all of the output wavelengths are engaged at the arrival instant of the burst, a switch adopting the BD technique discards only the initial part of a burst finding all of the engaged output wavelengths while forwarding the final part of the burst, beginning at the instant in which one wavelength becomes free. The OCBS allows an increase in the switch throughput in terms of number of accepted IP packets because a burst contains a given number of IP packets. We introduce the analytical model that allows us to evaluate the effectiveness of the technique and, in particular, the obtained saving; furthermore, a sensitivity analysis of the saving, with respect to both the optical burst switch parameters and the traffic load, is carried out.

Performance analyses of optical burst-switching networks

“…Since an OBS burst is an aggregation of many IP packets, there have been proposals to reduce packet loss probability by dumping a part of one of the two colliding bursts only during the collision time [1], [11]. For such proposals, we use the generic name burst segmentation.…”

“…• Burst segmentation (BS) [1], where the control packet is aware of the burst length and reserves the wavelength (bandwidth) starting from the first moment it becomes available until the remainder of the burst is transmitted. The initial data within the burst is discarded until the required wavelength on the output fiber becomes free, whereupon the remainder of the burst is successfully transmitted.…”

Blocking probabilities of optical burst switching networks based on reduced load fixed point approximations

“…Note also that an exact solution for IP packet loss probability under the assumption that packets are exponentially distributed appears in [3]. In principle, the solution of [3] can also replace (2).…”

“…Since an OBS burst is an aggregation of many IP packets, one can significantly reduce the packet loss probability in OBS networks by applying a technique called Optical Composite Burst Switching (OCBS) [3] also called Burst Segmentation [15] that discards only the initial part of a burst until a wavelength becomes free on the output fibre. From that instant, the switch will transmit the remainder of the burst [15].…”

“…• The Burst Segmentation [3] and [15], whereby the reservation (control) packet is aware of the burst length and reserves the wavelength (bandwidth) starting from the first moment it becomes available until the remainder of the burst is transmitted. In this case, the initial part of the burst until the required wavelength on the output fibre becomes free, is discarded and the remainder of the burst is successfully transmitted.…”