Performance Analysis of Multi-Fiber Synchronous Photonic Share-per-link Packet Switches Ayman G. Fayoumi, Fahad A. Al-Zahrani, Abdulgader A. Habiballa, Anura P. Jayasumana Electrical and Computer Engineering Department Colorado State University, Ft. Collins, CO 80523 (Ayman, Fahad, Habiball)@engr.colostate.edu, Anura.Jayasumana@colostate.edu Abstract A performance model is presented for an optical packet switch architecture in which the wavelength converters are shared per output link and each output link consists of multiple fibers. Symmetry of the switch is exploited to de- rive the packet loss probability for the case where traffic is destined to different output ports with equal probabil- ity. The architecture performance is evaluated by means of an analytical model and confirmed by simulations un- der different switch parameter configurations. Wavelength converters are shown to improve the packet loss probabil- ity of the switch. The study shows that synchronous switches equipped with full conversion would have the least conver- sion utilization rate indicating that the use of a switch with less converter count, i.e., partial conversion, would offer better switch resources utilization and comparable packet loss performance. 1. Introduction The necessity for a huge bandwidth and transparent high speed data transmission has been triggered by the explosive growth in the Internet traffic. All-optical network employ- ing wavelength division multiplexing (WDM) as multiplex- ing technology emerges as an innovative solution for the growing traffic explosion problem. WDM technology di- vides the optical spectrum into a number of non-overlapping wavelengths. Each wavelength is considered as a single communication channel operating at its peak electronic speed [4, 12, 14]. In all-optical networks, the data streams that flow between a source-destination pair remains in the optical domain throughout their paths except at the end nodes, providing transparency with respect to data format. The multiplexing technology provided by WDM introduces the means of effectively utilizing fiber bandwidth [2]. Using the conventional circuit-switched networks (wavelength-routed network), where a connection (light- path) between source-destination pair is established on top of the WDM multiplexing technology before data trans- mission begins, will result in ineffective use of the bandwidth provided by such technology [8]. To over- come this inherent poor utilization of the WDM channels in wavelength-routed networks, optical packet switch- ing (OPS), which allows fast allocation of wavelengths on demand, is introduced. OPS suffers from the packet con- tention problem that arises when two or more of the in- coming packets on the same wavelength intend to leave the switch through the same output port, which results in packet loss and poor network performance. The con- tention resolution schemes in optical switches could be implemented in time dimension [9, 11], in space dimen- sion [6], or in both at the same time. Wavelength conversion (WC) [7] is an example of fre- quency dimension contention resolution techniques. In this scheme multiple wavelengths are utilized to resolve the con- tention. The contention could be cleared by shifting all but one of the contending packets to unused wavelengths on the requested output link. The wavelength translation of pack- ets takes place by utilizing a wavelength converter. Using wavelength conversion (WC) with OPS reduces the pack- ets loss due the contentions. Furthermore, WCs are used to eliminate the severity of wavelength continuity constraint [5], and improve wavelength agility for dynamic realloca- tion of optical channels, which in turn enhances the perfor- mance and scalability of the network. The load correlation among wavelengths was considered in [13] with a fixed-alternate routing algorithm. The ana- lytical model in [13] is computationally complex, although its accuracy is limited especially for large networks. Wave- length conversion device is an expensive element [3], thus the number of converters could be considered as the criti- cal cost parameter in OPS design. As such, in this paper we presented results for an optical packet switch with a lim- ited number of converters per output. In this paper, we study synchronous OPS with limited number of converters that are shared between all wave- Proceedings of the IEEE Conference on Local Computer Networks 30th Anniversary (LCN’05) 0-7695-2421-4/05 $20.00 © 2005 IEEE