Memory optimization in single chip network switch fabrics

Moving high bandwidth (10Gb/s+) network switches from the large scale, rack mount design space to the single chip design space requires a re-evaluation of the overall design requirements. In this paper, we explore the design space for these single chip devices by evaluating the ITRS. We find that unlike ten years ago when interconnect was scarce, the limiting factor in today's designs is on-chip memory. We then discuss an architectural technique for maximizing the effectiveness of queue memory in a single chip switch. Next, we show simulation results that indicate that a more than two order of magnitude improvement in dropped packet probability can be achieved by re-distributing memory and allowing sharing between the switch's ports. Finally, we evaluate the cost of the optimized architecture in terms of other on-chip resources.