Characterizing and Simulating the Performance of the Physical Layer of Data Vortex Switching Nodes

Introduction Photonic packet switching fabrics are emerging as an attractive solution for ultra-high bandwidth, low switching latency interconnection within next -generation high-performance computing architectures. This is because lightwave networks are not limited by the conventional bottlenecks found in electronic systems, and have demonstrated the transmission of gargantuan volumes of data [1]. Furthermore, by utilizing intelligent routing procedures, the latency of such networks can be reduced to speed-of-light limitations. A topology for a switching fabric with minimal routing logic, designed specifically for photonic implementation, has been recently demonstrated and evaluated [24]. Termed the Data Vortex, this topology employs implicit synchronous signaling and routing, thereby eliminating the need for optical buffering. The predominant switch elements considered for optical packet networks have been semiconductor optical amplifiers (SOAs) due to their fast switching times, low switching power, and high extinction ratio [5]. Furthermore, in addition to switching, SOAs may be configured to re-amplify the signal and compensate for routing and transmission losses. The primary limitation of SOAs is the in -band signal noise introduced due to amplified spontaneous emissions (ASE). Crosstalk and other effects also contribute to an increase in the signal’s bit error rate (BER) as it propagates through the switching nodes [6]. The present work characterizes and simulates signal propagation through the physical layer of the Data Vortex switching fabric. Because traditional time-domain physical modeling techniques such as those based on rate equations, traveling wave analyses, and transfer matrix methods (viz. [6-8]) require precise knowledge of a myriad of physical parameter values, they are often quite difficult to implement. Instead of relying on physical analyses, we capture the essence of the signal distortions and perform the modeling from a signal-level phenomenological perspective. In order to construct the model, experimental data was collected from a number of actual Data Vortex switching nodes using optical packets with 10Gbit/sec payloads. It should also be noted that the methodology described herein can be applied to systems with differing architectures in a straightforward manner.