Research On Router Switching Fabric And Network Topology For High Radix Interconnection Network

ABSTRACT:High Performance Computer (HPC) is now entering EFLOPS era. As the most important infrastructure in HPC, high performance system interconnection network is facing more design challenges. Enabled by advancements in VLSI chip design process, especially in high bandwidth serial transport technology, high performance system interconnection network paves the way to high radix network. More narrow ports prefer to less wide ports are integrated into one router. High radix network has many merits than tranditional lower radix network, such as less network diameter, lower network latency, higher network performance and robusibility, and lower network cost.High radix router chip is the key component in high radix network. Once more high data rate ports are integrated, it is the most important challenge to design a scalable switching fabric, which should use limited on-chip design resources but can achieve high throughput, and should be structuaral both for frontend logical design and backend physical design. Two innovative resolutions are provided in this paper. The first one is asymmetric crossbar based switching fabric. For asymmetric crossbars, where number of input ports is much less than that of output ports in the same crossbar, theory analysis and RTL level simulation both reveals that high throughput can be achieved due to lower confliction in the ouput ports. A structural implemention of this switching fabric is also introduced. The second one is Dichotomy Partitioned Crossbar based switching fabric. For any crossbar, when lower down its input rate, confliction probability will also be lower down and result in higher relative throughput. Once input rate is lower than the saturation rate, the crossbar can achieve100%relative throughput. Herin, based on a special low input rate crossbar, named Dichotomy Partitioned Crossbar, which input rate in each input port is nearly50%, a low cost switching fabric named ADPC is provided. ADPC can achieve nearlly100%throughput in theory and can be easily implemented in TILE-based fabric. Contrast to YARC, which is the first high radix router, ADPC uses much less design resource.High radix router provides more design choices for high performance network topology. Some high radix network topologies are analysised in this paper. Based on traditional K-Ary N-Cube topology, an innovative topology named K-Ary N-Bridge is introduced. Contrast to K-Ary N-Cube topology, where K nodes in one dimension are connected in torus mode, K-Ary N-Bridge topology connects K nodes in one dimention through a K radix router. Thus K-Ary N-Bridge topology can fully make use of the high radix property of the router, cut down the network diameter, enhance the network performance, and keep excellent scalability.