A high-performance switch architecture based on mesh of trees

With emergence of various new Internet-enabled devices, such as tablet PCs or smart phones along with their own applications, the traffic growth rate is getting faster and faster these days and demands more communication bandwidth at even faster rate than before. To accommodate this ever-increasing network traffic, even faster Internet routers are required. To respond for these needs, we propose a new mesh of trees based switch architecture, called MOTS(N) switch. In addition, we also propose two more variations of MOTS(N) to further improve it. MOTS(N) is inspired by crossbar with crosspoint buffers. It forms a binary tree for each output line, where each gridpoint buffer is a leaf node and each internal node is 2-in 1-out merge buffer emulating FIFO queues. Because of this FIFO characteristic of internal buffers, MOTS(N) ensures QoS like FIFO output-queued switch. The root node of the tree for each output line is the only component connected to the output port where each cell is transmitted to output port without any contention. To limit the number of buffers in MOTS(N) switch, we present one of its improved (practical) variations, IMOTS(N) switch, as well. For IMOTS(N) switch architecture, sizes of the buffers in the fabric are limited by a certain amount. As a downside of IMOTS(N), however, every cell should go through log N-2+1 number of buffers in the fabric to be transmitted to the designated output line. Therefore, for even further improvement, IMOTS(N) with cut-through, denoted as IMOTS-CT(N), is also proposed in this paper. In IMOTS-CT(N) switch, the cells can cut through one or more empty buffers to be transferred from inputs to outputs with simple 1 or 2bit signal exchanges between buffers. We analyze the throughput of MOTS(N), IMOTS(N), and IMOTS-CT(N) switches and show that they can achieve 100% throughput under Bernoulli independent and identically distributed uniform traffic. Our quantitative simulation results validate the theoretical analysis. Copyright (c) 2012 John Wiley & Sons, Ltd.